JP3231420B2 - Electrorheological fluid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrorheological fluid. More specifically, a large shear stress is generated even by applying a relatively weak electric field, the current density flowing at that time is excellent in current characteristics that it is small, the generated shear stress and the stability of the current density over time are excellent, and Low initial viscosity when no electric field is applied, low 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) and redispersibility (separation of the dispersed phase The present invention relates to an electrorheological fluid which is particularly excellent in its ability to reproduce the original uniform state with a simple external force after it becomes non-uniform after floating.

[0002]

2. Description of the Related Art An electrorheological fluid is a fluid obtained by, for example, dispersing and suspending solid particles in an insulating dispersion medium, and its rheological or flow properties are viscoplastic due to an electric field change. It is a fluid that changes into a mold property, and is generally known as a fluid exhibiting the so-called Winslow effect, in which the viscosity increases significantly when an external electric field is applied and a large shear stress is induced. Since the Winslow effect has the characteristic of quick response, the electrorheological fluid can be applied to engine mounts, clutches, dampers, brakes, shock absorbers, actuators, valves, ink jets, and the like. Attempted.

Heretofore, as an electrorheological fluid, a fluid in which solid particles such as cellulose, starch, soybean casein, and silica gel are dispersed in an insulating oil such as silicon oil, diphenyl chloride, and trans oil is known. . However,
Those using cellulose, starch, soybean casein, silica gel and the like have a problem that the generated shear stress is small.

On the other hand, as an electrorheological fluid generating a high shear stress, for example, a powder of an ion-exchange resin suspended in a higher alkyl ester of an aromatic carboxylic acid (JP-A-50-92278), A composition comprising a crystalline substance that conducts current along only one of the crystal axes, a dielectric liquid, and a steric stabilizer (Japanese Patent Application Laid-Open No. 1-170693) has been proposed. However, these electrorheological fluids are inferior in dispersion stability when no electric field is applied, redispersibility after they have settled or floated, and have increased viscosity or dispersion of the dispersion medium so that the dispersed phase does not separate. When the phase concentration is increased, there is a problem that the fluidity becomes poor.

As an example of an attempt to improve the dispersion stability, an electrorheological fluid having silica gel as a disperse phase includes a dispersion medium having a nitrogen atom and / or a hydroxyl group-containing group and an alkyl group having 4 to 24 carbon atoms. A method of adding a soluble polymer (Japanese Patent Application Laid-Open No. 61-259752) or a method of adding a polysiloxane such as amino-functionality to an electrorheological fluid using silica gel or aluminum silicate as a dispersion phase and silicon oil as a dispersion medium (particularly) Kaikai 61-44998, JP-A 62-95
397) has been proposed. However, these electrorheological fluids have a problem that not only the generated shear stress is small but also the initial viscosity is high.

In order to improve redispersibility, electrorheological fluids containing fine particles (JP-A-3-166295, JP-A-3-160094) have been proposed. However, these electrorheological fluids have poor dispersion stability when no electric field is applied, and have a problem that their performance as an electrorheological fluid becomes unstable.

[0007] Therefore, the electrorheological fluids reported so far have a large shear stress generated, have excellent stability over time of the generated shear stress and current density, have a low initial viscosity, and have a high dispersion stability and a low dispersion. It was not satisfied simultaneously with the four points of excellent dispersibility and was not practical for a wide range of applications.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of a conventional electrorheological fluid.

[0009] Therefore, an object of the present invention is to produce a large shear stress even when a relatively weak electric field is applied, and to provide an excellent current characteristic that the current density flowing at that time is small. Excellent stability over time, low initial viscosity when no electric field is applied, 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) and redispersion. An object of the present invention is to provide an electrorheological fluid which is particularly excellent in properties (the ability to reproduce the original uniform state with a simple external force after the dispersed phase settles or floats and becomes non-uniform).

[0010]

SUMMARY OF THE INVENTION The present invention relates to an electrorheological fluid containing a dispersed phase composed of dielectric particles having an average particle diameter of 1 to 50 μm, a dispersion medium composed of a silicon-based insulating liquid, and additives. The structural unit (a) represented by the general formula-(SiR ¹ R ² O)-(wherein R ¹ and R ² are each independently an alkyl group or an aryl group) as an additive. and / or the general formula _{^{(R 3 3 SiO) 3 Si-}} ( provided that wherein R ³ is an alkyl group or an aryl group.) average molecular weight has a structural unit (b) as a main structural unit represented by the Silicon-based polymerizable with 400 or more
Double bond monomer (A) 3 to 70 wt% with the general formula _{^{- (R 4 -O) n -}} ( where, wherein R ⁴ is an alkylene group having 2 to 4 carbon atoms, n represents 4 . above a number structural unit represented by) (c) and / or the general formula ^{_{- (CH 2 -CR 5 X)}} - ( provided that wherein R ⁵ is hydrogen or methyl, X is -
CN or —COOR ⁶ , wherein R ⁶ is an alkyl group having 1 to 4 carbon atoms. A) a monomer having a polymerizable double bond having an average molecular weight of 400 or more and having a structural unit (d) represented by the following formula (d) as a main structural unit: 0.5 to 40% by weight;
And a polymerizable double bond other than the monomers (A) and (B)
Monomer (C) 0 to 90 wt% with (where the monomer (A), (B) the total of and (C) is 100 wt%.) By polymerizing a monomer component consisting of The present invention relates to an electrorheological fluid characterized in that the obtained copolymer (I) is used in a range of 0.1 to 30 parts by weight based on 100 parts by weight of a dispersed phase. The term “polymerizable” used in the present invention
"Monomer" refers to a polymerizable double bond throughout the specification.
Monomer ".

[0011]

The dielectric particles serving as the dispersed phase of the electrorheological fluid of the present invention must have an average particle diameter in the range of 1 to 50 μm. When the average particle size of the dispersed phase is less than 1 μm, a large shear stress cannot be obtained when an electric field is applied to the prepared electrorheological fluid. The average particle diameter of the dielectric particles is 5
When the thickness exceeds 0 μm, an electrorheological fluid having excellent dispersion stability without applying an electric field cannot be obtained.

The dielectric particles serving as the dispersed phase of the electrorheological fluid of the present invention are not limited as long as they are particles that are polarized under the application of an electric field, and may be any of an ionic polarization type, a dipole polarization type, an electron polarization type, and an interface polarization type. Type particles may be used. Such particles include, for example, organic polymer or inorganic particles having an ion exchange ability, inorganic dielectric particles composed of two or more atoms having greatly different electronegativities, hydroxyl groups, amino groups, amide groups and carbonyl groups. Organic polymer particles containing a functional group having a polarity such as, or composite particles obtained by insulating the surface of a conductor such as a metal or carbon. Organic polymer particles are preferable, and particles composed of a sulfonic acid group-containing polystyrene polymer are particularly preferable.

The sulfonic acid group-containing polystyrene-based polymer has a cation which can be dissociated in the presence of a polar solvent such as water, but the type of the cation is not particularly limited. Metal cations such as lithium ion, sodium ion, potassium ion, calcium ion, magnesium ion, aluminum ion, cuprous ion and cupric ion; organic cations such as tetramethylammonium ion and pyridinium ion; Can be.

The method for obtaining the dielectric particles that can be used as a dispersed phase in the present invention is not particularly limited, and may be synthesized by a known method, or a commercially available product may be used as it is or may be subjected to post-treatment such as grinding if necessary. Is also good.

It is necessary to use a silicon-based insulating liquid as a dispersion medium of the electrorheological fluid of the present invention. The silicon-based insulating liquid that can be used for the dispersion medium is substantially composed of silicon oil as a main component. There is no particular limitation as long as it is an electrically insulating liquid. Examples thereof include polydimethylsiloxanes such as polydimethylsiloxane, partially octyl-substituted polydimethylsiloxane, and partially phenyl-substituted polydimethylsiloxane; and silicone oils such as polydiphenylsiloxane. And one or more of these can be used. If necessary, a mixture of a hydrocarbon-based insulating liquid such as cyclohexylbenzene or dodecylbenzene or another insulating liquid such as a halogen-containing insulating liquid in a range of 50% by weight or less in the dispersion medium is used. be able to.

In general, since the dispersion stability of an electrorheological fluid largely depends on the interaction between a dispersed phase and an additive in a dispersed state, it is necessary that the adsorbing ability of the additive to the dispersed phase is large. is there. On the other hand, the greater the interaction between the dispersed phase and the dispersed phase and the additive in the settled layer after the dispersed phase has settled, the worse the redispersibility is. It is necessary to reduce the density.

[0017] As a result of investigations for realizing such an apparently contradictory adsorption behavior of the additive to the disperse phase in the silicon-based insulating liquid, the present invention has been achieved. That is, the additive used in the present invention includes a block of a silicon-based structural unit having a high affinity for the silicon-based insulating liquid of the dispersion medium and a structural unit containing a nitrogen atom and / or an oxygen atom having a high affinity for the dispersed phase. It is a copolymer that has a block and partially or wholly swells in a silicon-based insulating liquid. Such a copolymer improves the dispersion stability and redispersibility of an electrorheological fluid. It turned out to be effective.

Therefore, the additive used in the electrorheological fluid of the present invention comprises the structural unit (a) represented by the above general formula.
And / or a silicon-based polymerizable monomer (A) having a structural unit (b) as a main constituent unit and an average molecular weight of 400 or more, a structural unit (c) and / or a structural unit represented by the above general formula It is obtained by polymerizing a monomer component comprising (d) as a main structural unit, a polymerizable monomer (B) having an average molecular weight of 400 or more and, if necessary, another polymerizable monomer (C). It is a copolymer (I).

The copolymer (I) as an additive of the electrorheological fluid of the present invention contains, as a raw material monomer thereof, the aforementioned silicon-based polymerizable monomer (A) in an amount of 3 to 3 in all monomer components. 70% by weight
It is necessary to use within the range. When the amount of the silicon-based polymerizable monomer (A) used is less than 3% by weight or more than 70% by weight, it is impossible to greatly improve the dispersion stability of the prepared electrorheological fluid.

The content of the structural unit (a) and / or the structural unit (b) in the silicon-based polymerizable monomer (A) is not particularly limited. It is preferably at least 20% by weight in the body (A).

Such a silicon-based polymerizable monomer (A)
Examples thereof include vinyl group-containing polydimethylsiloxane, (meth) acryloyl group-containing polydimethylsiloxane, styryl group-containing polydimethylsiloxane, vinyl group-containing partially octyl-substituted polydimethylsiloxane, and (meth) acryloyl group-containing partially octyl-substituted polydimethylsiloxane. Styryl group-containing partially octyl-substituted polydimethylsiloxane, vinyl group-containing partially phenyl-substituted polydimethylsiloxane, (meth) acryloyl group-containing partially phenyl-substituted polydimethylsiloxane, styryl group-containing partially phenyl-substituted polydimethylsiloxane, and tris (trimethylsiloxy) silyl Propyl (meth) acrylate and the like can be mentioned, and one or more of these can be used.

The copolymer (I) as an additive of the electrorheological fluid of the present invention contains, as a raw material monomer, the above-mentioned polymerizable monomer (B) in an amount of 0.5 to 0.5 in all monomer components. It is necessary to use it in the range of 40% by weight. When the amount of the polymerizable monomer (B) used is less than 0.5% by weight or more than 40% by weight, it is impossible to greatly improve the dispersion stability of the prepared electrorheological fluid.

The content of the structural unit (c) and / or the structural unit (d) in the polymerizable monomer (B) is not particularly limited, but the polymerizable monomer is converted into a nitrogen atom and / or an oxygen atom. It is preferably at least 5% by weight in the body (B).

As such a polymerizable monomer (B),
For example, (meth) acryloyl group-containing polyethylene glycol, styryl group-containing polyethylene glycol, p-isopropenylbenzyl group-containing polyethylene glycol,
(Meth) acryloyl group-containing polypropylene glycol, styryl group-containing polypropylene glycol, p-isopropenylbenzyl group-containing polypropylene glycol, (meth) acryloyl group-containing polytetramethylene glycol, styryl group-containing polytetramethylene glycol, p-isopropenylbenzyl group Polyalkylene glycols having a polymerizable double bond such as polytetramethylene glycol containing poly (methyl (meth) acryloyl group), poly (methyl (meth) acrylate containing styryl group), p-vinylbenzyl group Poly (methyl) methacrylate, p-isopropenylbenzyl group-containing poly (meth) acrylate, allyl group-containing poly (meth) acrylate, (meth) acryloyl group-containing poly (meth) acrylate Butyl Le acid, p- vinylbenzyl group-containing poly (meth) butyl acrylate, p- isopropenyl benzyl group-containing poly (meth) acrylate, butyl (meth) acryloyl group-containing (acrylonitrile -
(Styrene) copolymers and other (meth) acrylic acid ester-based polymers or acrylonitrile-based polymers having a polymerizable double bond, and one or more of these can be used. .

The copolymer (I) to be used as an additive of the electrorheological fluid of the present invention has a monomer (A) and a
(C) having a polymerizable double bond other than (B) and (B )
Can be used in a range of 90% by weight or less based on all the monomer components.

As such a polymerizable monomer (C),
For example, olefins such as ethylene, propylene, butylene, pentene, hexene, heptene, octene, cyclopentene and cyclohexene; vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, vinyl chloride, vinylidene chloride, vinylene chloride, odor Halogenated olefins such as vinyl chloride; alkyldienes such as butadiene, isoprene and cyclopentadiene;
Styrene, methyl styrene, ethyl styrene, propyl styrene, butyl styrene, pentyl styrene, vinyl naphthalene, methyl vinyl naphthalene, ethyl vinyl naphthalene, propyl vinyl naphthalene, butyl vinyl naphthalene, pentyl vinyl naphthalene, hexyl vinyl naphthalene, vinyl anthracene, methyl vinyl anthracene , Ethyl vinyl anthracene, propyl vinyl anthracene, butyl vinyl anthracene, pentyl vinyl anthracene, hexyl vinyl anthracene, vinyl phenanthrene, methyl vinyl phenanthrene, ethyl vinyl phenanthrene, propyl vinyl phenanthrene, butyl vinyl phenanthrene, pentyl vinyl phenanthrene, hexyl vinyl phenanthrene, fluorostyrene , Chloros Ren, bromostyrene, dichloro styrene, trichloro styrene, tetra-chlorostyrene, chloromethylstyrene, hydroxymethylstyrene, aminomethyl styrene, chloro-vinyl naphthalene,
Aryl alkenes such as chlorovinyl anthracene and chlorovinyl phenanthrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth) ) (Meth) acrylic esters such as hexyl acrylate and hydroxyethyl (meth) acrylate; (meth) acrylamides such as (meth) acrylamide and dimethyl (meth) acrylamide; methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and pentyl Vinyl ethers such as vinyl ether and hexyl vinyl ether; vinyl esters such as vinyl acetate, vinyl trifluoroacetate and vinyl pentafluoropropionate; allyl acetate, allyl acetonitrile, and allyl Polymerizable substituted allyls such as alcohol, allylamine, diallylamine, triallylamine, allyl cyanide, diallyl ether, allyl ethyl ether, allyl toluyl ether; dimethyl fumarate, diethyl fumarate, dibutyl fumarate, diphenyl fumarate, diamyl fumarate, etc. Fumaric esters;
Maleic esters such as dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, diamyl maleate and diphenyl maleate;
(Meth) acrolein, chloro (meth) acrolein,
Unsaturated aldehydes such as crotonaldehyde; unsaturated ketones such as methyl vinyl ketone and ethyl vinyl ketone;
Unsaturated lactams such as vinylpyrrolidone; unsaturated amines such as dimethylvinylamine and diethylvinylamine;
Unsaturated nitriles such as (meth) acrylonitrile and cyanovinylidene; divinylbenzene, vinylpropenylbenzene, vinylisopropenylbenzene, vinylisobutenylbenzene, diisopropenylbenzene, isopropenylisobutenylbenzene, diisobutenylbenzene, divinylmethyl Benzene, divinylethylbenzene, divinyldimethylbenzene, trivinylbenzene,
Polyfunctional polymerizable aromatic compounds such as triisopropylbenzene, divinylnaphthalene, vinylisopropylnaphthalene, diisopropylnaphthalene, divinylanthracene, divinylphenanthrene; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) )
Acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) Acrylate,
1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth)
Acrylate, dipentaerythritol penta (meth)
Acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropanetetra (meth)
Acrylate, glycerol di (meth) acrylate,
Polyfunctional polymerizable (meth) acrylate derivatives such as tetramethylolmethanetri (meth) acrylate and tetramethylolmethanetetra (meth) acrylate; N, N'-
Methylenebis ((meth) acrylamide), N, N'-
Polyfunctional polymerizable (meth) acrylamide derivatives such as ethylenebis ((meth) acrylamide); polyfunctional polymerizable allyl derivatives such as diethylene glycol diallyl ether, diallyl chlorendate, diallyl phthalate, diallyl hexahydrophthalate, triallyl trimellitate And the like, and one or more of them can be used. Among these other polymerizable monomers (C), arylalkenes such as styrene and divinylbenzene are particularly preferable in view of polymerization reactivity and performance of the obtained electrorheological fluid.

The method for obtaining the copolymer (I) as an additive for the electrorheological fluid of the present invention is not particularly limited, and examples thereof include a silicon-based polymerizable monomer (A), a polymerizable monomer (B) and A radical polymerization method in which a monomer component composed of another polymerizable monomer (C) is used, if necessary, using a polymerization catalyst such as a peroxide, an azo compound, or a redox system, and other additives as necessary. it can. Known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, dispersion polymerization, precipitation polymerization and suspension polymerization can also be used, and among these, solution polymerization, dispersion polymerization, and precipitation polymerization in an alcohol-based solvent can be used. A polymerization method such as polymerization is preferred from the viewpoint of the performance of the electrorheological fluid using the obtained copolymer. Further, after the polymerization, if necessary, post-treatment can be performed by a known method such as reprecipitation purification, solvent replacement, solvent evaporation, drying and pulverization. In particular, when the polymerization solvent is solvent-substituted with silicone oil and used as an additive after the silicone oil dispersion of the copolymer (I) is used,
This is preferable because the workability in preparing the electrorheological fluid is improved.

The copolymer (I) used as an additive in the electrorheological fluid of the present invention is used in an amount of 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, per 100 parts by weight of the dispersed phase. It is necessary to use. When the amount of the polymer dispersant used is less than 0.1 part by weight with respect to the dispersed phase, the dispersion stability of the electrorheological fluid cannot be sufficiently improved. If the amount exceeds 30 parts by weight, dispersion stability corresponding to the added amount may not be obtained, or the initial viscosity of the electrorheological fluid may be remarkably increased to cause practical problems.

The electrorheological fluid of the present invention is obtained by mixing and dispersing the above-mentioned dielectric particles to be a dispersed phase in a dispersion medium comprising a silicon-based insulating liquid in the presence of a copolymer (I) as an additive. It is obtained.

The ratio of the dispersion phase to the dispersion medium in the electrorheological fluid of the present invention is such that the former is 100 parts by weight and the latter is 50 to 5
It is preferably in the range of 00 parts by weight. If the amount of the dispersion medium exceeds 500 parts by weight, the shear stress obtained when an electric field is applied to the prepared electrorheological fluid may not be sufficiently large. In addition, when the amount of the dispersion medium is less than 50 parts by weight, the fluidity of the prepared composition itself is reduced, and it may be difficult to use the composition as an electrorheological fluid.

The electrorheological fluid of the present invention may contain, for example, known polymer dispersants, surfactants, polymer thickeners, fine particles and other additives for adjusting the viscosity or improving the shear stress. Conventionally known various additives can be added.

[0032]

EXAMPLES The present invention will be described below with reference to examples, but the scope of the present invention is not limited only to these examples.

[0033]

Reference Example 1 In a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 567 g of isopropyl alcohol, 6 g of azobisisobutyronitrile, and a silicon-based polymerizable monomer (A) were prepared. Methacryloyl group-containing polydimethylsiloxane (Silaprene FM0721 manufactured by Chisso Corporation, average molecular weight = about 500
0, silicon content = 36%) 30 g, methacryloyl group-containing methoxypolyethylene glycol (NK ester M-230G manufactured by Shin-Nakamura Chemical Co., Ltd., polymerizable monomer (B), polymerization degree n = polyethylene glycol = About 23, average molecular weight = about 1100, oxygen content = 37%)
10 g, styrene 4 as another polymerizable monomer (C)
0 g and 20 g of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the mixture was stirred at room temperature for 30 minutes while blowing nitrogen. This was heated at 65 ° C. for 20 hours and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. 20 c
s silicone oil (KF96 manufactured by Shin-Etsu Chemical Co., Ltd.)
-20cs) After adding 400 g dropwise, the volatiles were distilled off by heating under reduced pressure with an evaporator, and a silicone oil dispersion of the copolymer (1) (copolymer (1) content 20% by weight, Hereinafter, an additive dispersion (1) was obtained.

[0034]

Reference Example 2 700 g of isopropyl alcohol, 6 g of azobisisobutyronitrile, 5 g of polyvinylpyrrolidone, silicon-based polymerizable monomer in a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube As (A), a methacryloyl group-containing polydimethylsiloxane (Silaprene FM071 manufactured by Chisso Corporation)
1, average molecular weight = about 1000, silicon content = 33%)
7 g, methacryloyl group-containing polyethylene glycol (Blenmer PE-350 manufactured by NOF Corporation, degree of polymerization of polyethylene glycol = 7) as polymerizable monomer (B)
-9, average molecular weight = about 450, oxygen content = 37%)
1.5 g, 90.5 g of styrene as another polymerizable monomer (C) and 3 g of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) And stirred at room temperature for 30 minutes while blowing in nitrogen. This was heated at 65 ° C. for 20 hours and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. 10c
s silicone oil (KF96 manufactured by Shin-Etsu Chemical Co., Ltd.)
-10 cs) 400 g was added dropwise, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a silicone oil dispersion of copolymer (2) (copolymer (2) content 20% by weight, Hereinafter, an additive dispersion (2) was obtained.

[0035]

Reference Example 3 In a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 567 g of isopropyl alcohol, 5 g of azobisisobutyronitrile, and a silicon-based polymerizable monomer (A) were prepared. Methacryloyl group-containing polydimethylsiloxane (Silaprene FM0725 manufactured by Chisso Corporation, average molecular weight = about 1000)
0, silicon content = 37%) 60 g, methacryloyl group-containing polyethylene glycol tetraethylene glycol as polymerizable monomer (B) (Blenmer 55 PET-800, manufactured by NOF Corporation, degree of polymerization of polyethylene glycol = 10) (Polytetramethylene glycol polymerization degree = 5, average molecular weight = about 900, oxygen content = 31%)
30 g and 10 g of industrial divinylbenzene (a mixture of 55% by weight of divinylbenzene, 35% by weight of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) as the other polymerizable monomer (C) were charged, and nitrogen was blown thereinto. Stirred at room temperature for 30 minutes. This is heated at 65 ° C. for 20 hours and further heated to 83 ° C.
For 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured.
%was. 392 g of 20 cs silicone oil (KF96-20 cs, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to the reaction solution, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a copolymer (3). A silicone oil dispersion (copolymer (3) content 20% by weight, hereinafter referred to as additive dispersion (3)) was obtained.

[0036]

Reference Example 4 300 g of isopropyl alcohol, 267 g of toluene, 3 g of benzoyl peroxide, and 3 g of a silicon-based polymerizable monomer (A) were placed in a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Methacryloyl group-containing polydimethylsiloxane (Silaprene FM0725 manufactured by Chisso Corporation, average molecular weight =
Approximately 10000, silicon content = 37%) 15 g, methacryloyl group-containing (acrylonitrile-styrene) copolymer (Toa Gosei Chemical Industry Co., Ltd.) as a polymerizable monomer (B)
Macromonomer AN-6, average molecular weight = about 600
0, nitrogen content = 5.8%) (10 g), 70 g of styrene and 10 g of diallyl phthalate as other polymerizable monomers (C) were added, and the mixture was stirred at room temperature for 30 minutes while blowing in nitrogen. This was heated at 70 ° C. for 20 hours and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured.
%was. 400 g of 20 cs silicone oil (KF96-20 cs, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to the reaction solution, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a copolymer (4). A silicone oil dispersion (copolymer (4) content 20% by weight, hereinafter referred to as additive dispersion (4)) was obtained.

[0037]

REFERENCE EXAMPLE 5 400 g of isopropyl alcohol, 167 g of toluene, 4 g of azobisisobutyronitrile, 4 g of silicon-based polymerizable monomer and a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube were used. A) tris (trimethylsiloxy) silylpropyl methacrylate (X-22 manufactured by Shin-Etsu Chemical Co., Ltd.)
-5002, molecular weight = about 422, silicon content = 26
%) 30 g, methacryloyl group-containing polymethyl methacrylate (macromonomer AA-6 manufactured by Toa Gosei Chemical Industry Co., Ltd., average molecular weight = about 6) as a polymerizable monomer (B)
000, oxygen content by elemental analysis = 32%) 10 g,
50 g of styrene and 10 g of hexamethylene dimethacrylate were added as other polymerizable monomers (C), and the mixture was stirred at room temperature for 30 minutes while blowing in nitrogen. 65 ℃
For 20 hours, and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. 400 g of 20 cs silicon oil (KF96-20 cs, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to the reaction solution, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a copolymer (5). Silicon oil dispersion (Copolymer (5)
20% by weight (hereinafter referred to as additive dispersion (5)).

[0038]

Reference Example 6 400 g of isopropyl alcohol, 4 g of azobisisobutyronitrile, and a silicon-based polymerizable monomer (A) were placed in a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Methacryloyl group-containing polydimethylsiloxane (Silaprene FM0721 manufactured by Chisso Corporation, average molecular weight = about 500
0, silicon content = 36%) 30 g, methacryloyl group-containing polybutyl acrylate (macromonomer AB manufactured by Toa Gosei Chemical Industry Co., Ltd.) as a polymerizable monomer (B)
-6, average molecular weight = about 6000, oxygen content = 28%)
20 g, styrene 4 as another polymerizable monomer (C)
0 g and 10 g of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the mixture was stirred at room temperature for 30 minutes while blowing in nitrogen. This was heated at 65 ° C. for 20 hours and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. 20 c
s silicone oil (KF96 manufactured by Shin-Etsu Chemical Co., Ltd.)
-20cs) After adding 400 g dropwise, the volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a silicone oil dispersion of the copolymer (6) (content of the copolymer (6) 20% by weight, Hereinafter, an additive dispersion (6) was obtained.

[0039]

Reference Example 7 In a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 567 g of isopropyl alcohol, 6 g of azobisisobutyronitrile, and a silicon-based polymerizable monomer (A) were prepared. Methacryloyl group-containing polydimethylsiloxane (Silaprene FM0721 manufactured by Chisso Corporation, average molecular weight = about 500
0, silicon content = 36%), 30 g, methacryloyl group-containing methoxypolyethylene glycol (NK ester M- manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polymerizable monomer (B)
230G, degree of polymerization of polyethylene glycol = about 23,
(Average molecular weight = about 1100, oxygen content = 37%) 10g
And styrene 60 as another polymerizable monomer (C).
g, and the mixture was stirred at room temperature for 30 minutes while blowing in nitrogen. This was heated at 65 ° C. for 20 hours and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. 400 g of 20 cs silicon oil (KF96-20 cs manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to the reaction solution, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a copolymer (7). A silicone oil dispersion (copolymer (7) content 20% by weight, hereinafter referred to as additive dispersion (7)) was obtained.

[0040]

Reference Example 8 In a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 567 g of isopropyl alcohol, 6 g of azobisisobutyronitrile, methoxypolyethylene glycol containing methacryloyl group (Shin Nakamura Chemical ( NK Ester M-230
G, degree of polymerization of polyethylene glycol = about 23, average molecular weight = about 1100, oxygen content = 37%) 10 g, styrene 70 g and industrial divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd., divinylbenzene 55% by weight, ethyl) 20 g of a mixture of 35% by weight of styrene and the like, and the mixture was stirred at room temperature for 30 minutes while blowing nitrogen. This at 65 ° C for 20
Then, the mixture was heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. 20
cs silicon oil (KF9 manufactured by Shin-Etsu Chemical Co., Ltd.)
6-20cs) 400 g was added dropwise, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a silicone oil dispersion of the copolymer (8) (copolymer (8) content 20% by weight). , Hereinafter referred to as comparative additive dispersion liquid (1))
I got

[0041]

REFERENCE EXAMPLE 9 567 g of isopropyl alcohol, 6 g of azobisisobutyronitrile, 5 g of polyvinylpyrrolidone, and polydimethylsiloxane containing a methacryloyl group (1000 g) were placed in a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. 30 g of Silaplane FM0721 manufactured by Chisso Corporation, average molecular weight = about 5000, silicon content = 36%), 40 g of styrene, and industrial divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd., 55% by weight of divinylbenzene, ethyl) 20 g of a mixture of 35% by weight of styrene and the like, and the mixture was stirred at room temperature for 30 minutes while blowing nitrogen. This is heated at 65 ° C. for 20 hours and further heated to 83 ° C.
For 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured.
It was 0%. 20 cs of silicone oil (KF96-20cs manufactured by Shin-Etsu Chemical Co., Ltd.) 400 was added to the reaction solution.
g of the copolymer (9), the volatile components are distilled off by heating under reduced pressure with an evaporator, and a silicone oil dispersion of the copolymer (9) (copolymer (9) content: 20% by weight;
Comparative additive dispersion liquid (2)) was obtained.

[0042]

Reference Example 10 400 g of ion-exchanged water, 4 g of sodium dodecylsulfonate and 1 g of sodium persulfate were put into a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube and dissolved. A monomer component consisting of 70 g of styrene and 30 g of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) is added and dispersed while blowing nitrogen. 200 by machine
The mixture was stirred at 00 rotation for 2 minutes. This was heated at 70 ° C. for 3 hours and further heated at 90 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. Water was distilled off by heating the reaction solution under reduced pressure using an evaporator, and then dried in an air oven at 80 ° C. overnight to obtain a fine particle copolymer (1).
0) (hereinafter referred to as comparative additive (3)). The average particle size of the comparative additive (3) measured from an electron micrograph was 0.1 μm.

[0043]

REFERENCE EXAMPLE 11 400 g of ion-exchanged water and 5 g of polyvinyl alcohol (Kuraray Poval PVA-205 manufactured by Kuraray Co., Ltd.) were charged into a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. 2 g of benzoyl peroxide was added to a monomer component composed of 70 g of styrene and 30 g of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.). The solution obtained by dissolution was added. The mixture was stirred at 15,000 rpm for 30 minutes with a disperser while blowing nitrogen, heated at 70 ° C. for 8 hours, and further heated at 90 ° C. for 4 hours to perform a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured to be 100%. The solid content in the reaction solution was separated by filtration, sufficiently washed with acetone and water, and then dried overnight in an air oven at 80 ° C. to obtain a fine particle copolymer (11).
(Hereinafter referred to as comparative additive (4)). The average particle size of the comparative additive (4) measured from an electron micrograph was 1 μm.

[0044]

Reference Example 12 400 g of isopropyl alcohol, 4 g of azobisisobutyronitrile, a silicon-based polymerizable monomer (A) in a 1000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Methacryloyl group-containing polydimethylsiloxane (Silaprene FM0721 manufactured by Chisso Corporation, average molecular weight = about 500
0, silicon content = 36%) 28 g, methacryloyl group-containing methoxypolyethylene glycol (NK ester M- manufactured by Shin-Nakamura Chemical Co., Ltd.) as a polymerizable monomer (B)
230G, degree of polymerization of polyethylene glycol = about 23,
(Average molecular weight = about 1100, oxygen content = 37%) 12
g, styrene 45 as another polymerizable monomer (C).
g, 10 g of diallyl phthalate and 5 g of butyl methacrylate, and the mixture was stirred at room temperature for 30 minutes while blowing in nitrogen. This was heated at 65 ° C. for 20 hours and further heated at 83 ° C. for 4 hours to carry out a polymerization reaction. The solid content of the obtained reaction solution was measured, and the polymerization rate of the monomer was measured.
%was. 400 g of 20 cs silicone oil (KF96-20 cs manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to the reaction solution, and then volatiles were distilled off by heating under reduced pressure with an evaporator to obtain a copolymer (12). Silicone oil dispersion (copolymer (12) content 20% by weight,
An additive dispersion (8) was obtained.

[0045]

Example 1 1200 g of ion-exchanged water and 16 g of polyvinyl alcohol (Kuraray Poval PVA-205 manufactured by Kuraray Co., Ltd.) were added to a 3000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. After dissolution, 250 g of styrene and industrial divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd., divinylbenzene 5)
Mixture of 5% by weight, 35% by weight of ethylstyrene)
g and 5 g of benzoyl peroxide. Thereafter, the contents of the flask were dispersed using a disperser (rotational speed: 4000 rpm), heated at 70 ° C. for 6 hours, and further heated at 90 ° C. for 2 hours. The obtained solid was separated by filtration, sufficiently washed with acetone and water, and dried at 80 ° C. for 12 hours using a hot air drier to obtain a polymer crosslinked product (hereinafter referred to as a polymer crosslinked product (1)). 291 g).

Then, 500 g of 98% by weight concentrated sulfuric acid was charged into a 1000 ml three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and the polymer crosslinked product (1) 10 was cooled with ice.
After adding 0 g, the mixture was heated at 80 ° C. for 24 hours with stirring to carry out a sulfonation reaction. Thereafter, the contents of the flask were poured into water at 0 ° C., and filtered and washed with water.

The obtained solid was neutralized with 380 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Thereafter, the resultant is dried at 80 ° C. for 10 hours using a vacuum drier, and is referred to as an organic polymer particle having an average particle diameter of 11 μm or less. ｝ 187 g were obtained. In addition,
The density of the anionic dissociating group of the dispersed phase particles (1) is 4.2 mg.
Equivalent / g.

After 30 g of the dispersed phase particles (1) were dried at 150 ° C. for 3 hours, left in a room at a temperature of 20 ° C. and a relative humidity of 60% for 30 minutes to absorb moisture, the additive dispersion obtained in Reference Example 1 was dispersed. 15 g of the liquid (1) was added to 55 g of 20 cs silicone oil (KF96-20 cs manufactured by Shin-Etsu Chemical Co., Ltd.) and dispersed uniformly in a dispersion medium to obtain the electrorheological fluid (1) of the present invention. Was.

[0049]

Example 2 35 g of the additive dispersion (2) obtained in Reference Example 2 was used in place of the additive dispersion (1) in Example 1, and 10 cs of silicone oil (Shin-Etsu) was used instead of 20 cs of silicone oil. KF96-1 manufactured by Chemical Industry Co., Ltd.
0cs) An electrorheological fluid (2) of the present invention was obtained in the same manner as in Example 1 except that 35 g was used.

[0050]

EXAMPLE 3 In place of the additive dispersion (1) in Example 1, 2.5 g of the additive dispersion (3) obtained in Reference Example 3
Using silicone oil (KF manufactured by Shin-Etsu Chemical Co., Ltd.)
An electrorheological fluid (3) of the present invention was obtained in the same manner as in Example 1 except that the amount of used (96-20 cs) was changed to 67.5 g.

[0051]

Example 4 Instead of the additive dispersion (1) in Example 1, 20 g of the additive dispersion (4) obtained in Reference Example 4 was used, and silicone oil (KF9 manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
The electrorheological fluid (4) of the present invention was prepared in the same manner as in Example 1 except that the amount of 6-20 cs) was changed to 50 g.
I got

[0052]

Example 5 Instead of the additive dispersion (1) in Example 1, 10 g of the additive dispersion (5) obtained in Reference Example 5 was used, and silicon oil (KF9 manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
The electrorheological fluid (5) of the present invention was produced in the same manner as in Example 1 except that the amount of 6-20cs) was changed to 60 g.
I got

[0053]

Example 6 Instead of the additive dispersion (1) in Example 1, 10 g of the additive dispersion (6) obtained in Reference Example 6 was used, and silicone oil (KF9 manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
The electrorheological fluid (6) of the present invention was prepared in the same manner as in Example 1 except that the amount of 6-6cs) was changed to 60 g.
I got

[0054]

Example 7 Instead of the additive dispersion (1) in Example 1, 15 g of the additive dispersion (7) obtained in Reference Example 7 was used, and silicone oil (KF9 manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
The electrorheological fluid (7) of the present invention was prepared in the same manner as in Example 1 except that the amount of 6-6cs) was changed to 60 g.
I got

[0055]

Example 8 1200 g of ion-exchanged water and 16 g of polyvinyl alcohol (Kuraray Poval PVA-205 manufactured by Kuraray Co., Ltd.) were added to a 3000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. After dissolution, 250 g of styrene and industrial divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd., divinylbenzene 5)
Mixture of 5% by weight, 35% by weight of ethylstyrene)
g and 5 g of benzoyl peroxide. Thereafter, the contents of the flask were dispersed using a disperser (rotation speed: 20,000 rpm), heated at 70 ° C. for 6 hours, and further heated at 90 ° C. for 2 hours. The obtained solid was separated by filtration, sufficiently washed with acetone and water, and dried at 80 ° C. for 12 hours using a hot air drier to obtain a polymer crosslinked product (hereinafter referred to as a polymer crosslinked product (2)). ) 278 g were obtained.

Then, 500 g of 98% by weight concentrated sulfuric acid was charged into a 1000 ml three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and the polymer crosslinked product (2) 10 was cooled with ice.
After adding 0 g, the mixture was heated at 80 ° C. for 24 hours with stirring to carry out a sulfonation reaction. Thereafter, the contents of the flask were poured into water at 0 ° C., and filtered and washed with water.

The obtained solid was neutralized with 370 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Then, it is dried at 80 ° C. for 10 hours using a vacuum drier, and is referred to as an organic polymer particle having an average particle diameter of 2.7 μm or less, hereinafter referred to as a dispersed phase particle (2). $ 181 g was obtained. In addition, the anionic dissociation group density of the dispersed phase particles (2) is 4.3.
mg equivalent / g.

30 g of the dispersed phase particles (2) were dried at 150 ° C. for 3 hours, left in a room at a temperature of 20 ° C. and a relative humidity of 60% for 20 minutes to absorb moisture, and then dispersed in the additive obtained in Reference Example 1. 15 g of the liquid (1) was added to 55 g of 20 cs silicone oil (KF96-20 cs manufactured by Shin-Etsu Chemical Co., Ltd.), and the mixture was uniformly dispersed in a dispersion medium to obtain an electrorheological fluid (8) of the present invention. Was.

[0059]

Example 9 1200 g of ion-exchanged water and 12 g of polyvinyl alcohol (Kuraray Poval PVA-205 manufactured by Kuraray Co., Ltd.) were added to a 3000 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. After dissolution, 250 g of styrene and industrial divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd., divinylbenzene 5)
Mixture of 5% by weight, 35% by weight of ethylstyrene)
g and 5 g of benzoyl peroxide. Thereafter, the contents of the flask were dispersed at 600 rpm, heated at 70 ° C. for 6 hours, and further heated at 90 ° C. for 4 hours. The obtained solid was separated by filtration, sufficiently washed with acetone and water, and dried at 80 ° C. for 12 hours using a hot air drier to obtain a polymer crosslinked product (hereinafter referred to as a polymer crosslinked product (3)). 294 g).

Next, 500 g of 98% by weight concentrated sulfuric acid was charged into a 1000 ml three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and the polymer crosslinked product (3) 10 was cooled with ice.
After adding 0 g, the mixture was heated at 80 ° C. for 24 hours with stirring to carry out a sulfonation reaction. Thereafter, the contents of the flask were poured into water at 0 ° C., and filtered and washed with water.

The obtained solid was neutralized with 370 ml of a 10% by weight aqueous sodium hydroxide solution, and then sufficiently washed with water. Then, it is dried at 80 ° C. for 10 hours using a vacuum drier, and is referred to as an organic polymer particle having an average particle diameter of 28 μm or less, hereinafter referred to as a dispersed phase particle (3). ｝ 188 g were obtained. The anionic dissociation group density of the dispersed phase particles (3) was 4.2.
mg equivalent / g.

After 32 g of the dispersed phase particles (3) were dried at 150 ° C. for 3 hours and left in a room at a temperature of 20 ° C. and a relative humidity of 60% for 40 minutes to absorb moisture, the additive dispersion obtained in Reference Example 1 was dispersed. 10 g of the liquid (1) was added to 58 g of 20 cs silicone oil (KF96-20 cs manufactured by Shin-Etsu Chemical Co., Ltd.), and the mixture was uniformly dispersed in a dispersion medium to obtain an electrorheological fluid (9) of the present invention. Was.

[0063]

Example 10 The additive dispersion (8) 25 obtained in Reference Example 12 was used instead of the additive dispersion (1) in Example 1.
g, silicone oil (K-Shin-Etsu Chemical Co., Ltd.)
An electrorheological fluid (10) of the present invention was obtained in the same manner as in Example 1, except that the amount of F96-20cs) was changed to 45 g.

[0064]

Comparative Example 1 30 g of dispersed phase particles (1) in Example 1
After drying at 150 ° C for 3 hours, the temperature was 20 ° C and the relative humidity was 60.
% In a room for 30 minutes to absorb moisture, and then 20 cs silicone oil (KF96-2 manufactured by Shin-Etsu Chemical Co., Ltd.)
0cs) mixed and dispersed in 70 g, and an electrorheological fluid ｛for comparison, hereinafter referred to as a comparative fluid (1). I got｝.

[0065]

Comparative Example 2 30 g of the dispersed phase particles (1) in Example 1
After drying at 150 ° C for 3 hours, the temperature was 20 ° C and the relative humidity was 60.
% Oil for 30 minutes and then absorbed in 10 cs silicone oil (KF96-1 manufactured by Shin-Etsu Chemical Co., Ltd.)
0cs) mixed and dispersed in 70 g and an electrorheological fluid 比較 for comparison, hereinafter referred to as comparative fluid (2). I got｝.

[0066]

Comparative Example 3 Instead of the additive dispersion (1) in Example 1, the comparative additive dispersion (1) 15 obtained in Reference Example 8 was used.
A comparative electrorheological fluid (hereinafter referred to as comparative fluid (3)) was prepared in the same manner as in Example 1 except that g was used. I got｝.

[0067]

Comparative Example 4 The comparative additive dispersion (2) 15 obtained in Reference Example 9 was used instead of the additive dispersion (1) in Example 1.
An electrorheological fluid for comparison ｛, hereinafter referred to as comparative fluid (4), in the same manner as in Example 1 except that g was used. I got｝.

[0068]

Comparative Example 5 The same procedure as in Example 1 was repeated except that 3 g of the comparative additive (3) obtained in Reference Example 10 was used instead of the additive dispersion (1), and the amount of silicon oil used was changed to 67 g. In the same manner as in Example 1, an electrorheological fluid for comparison {this is referred to as comparative fluid (5). I got｝.

[0069]

Comparative Example 6 The same procedure as in Example 1 was repeated except that 3 g of the comparative additive (4) obtained in Reference Example 11 was used instead of the additive dispersion (1), and the amount of silicon oil used was changed to 67 g. In the same manner as in Example 1, an electrorheological fluid for comparison {this is referred to as a comparative fluid (6). I got｝.

[0070]

Comparative Example 7 In place of the additive dispersion (1) in Example 1, a commercially available silicon-containing nitrogen-containing additive amino-modified silicone (KF8 manufactured by Shin-Etsu Chemical Co., Ltd.)
005) Use 10 g and reduce the amount of silicon oil used to 6
An electrorheological fluid for comparison {this is referred to as comparative fluid (7)) in the same manner as in Example 1 except that the amount was 0 g. I got｝.

[0071]

Comparative Example 8 30 g of the dispersed phase particles (2) in Example 8
After drying at 150 ° C for 3 hours, the temperature was 20 ° C and the relative humidity was 60.
% In a room for 20 minutes to absorb moisture, and then use 20 cs silicone oil (KF96-2 manufactured by Shin-Etsu Chemical Co., Ltd.).
0cs) mixed and dispersed in 70 g, and an electrorheological fluid ｛for comparison, hereinafter referred to as comparative fluid (8). I got｝.

[0072]

Comparative Example 9 32 g of dispersed phase particles (3) in Example 9
After drying at 150 ° C for 3 hours, the temperature was 20 ° C and the relative humidity was 60.
% In a room for 40 minutes to allow it to absorb moisture, and then use 20 cs silicone oil (KF96-2 manufactured by Shin-Etsu Chemical Co., Ltd.).
0cs) is mixed and dispersed in 68 g, and is referred to as an electrorheological fluid ｛for comparison, hereinafter referred to as a comparative fluid (9). I got｝.

[0073]

Example 11 Each of the electrorheological fluids (1) to (10) and comparative fluids (1) to (9) of the present invention obtained in Examples 1 to 10 and Comparative Examples 1 to 9 was heated at 23 ° C. The viscosity when no electric field was applied was measured. Then, each of the electrorheological fluids was poured from the bottom of a test tube 150 mm high and 15 mm in diameter from the bottom.
It was filled up to 00 mm and sealed. Thereafter, the sedimentation velocity of the dispersed phase particles was tracked at room temperature, and the time (unit: days) required for the dispersed phase particles to settle 5 mm from the liquid surface of the electrorheological fluid filled in the test tube was measured, and the dispersion stability was measured. Was evaluated. Then add 50ml of each electrorheological fluid to 100ml
After sealing for one month, put in a container of 30
The sample was rotated at the speed of rotation, and the total number of rotations required to return to the original uniform state was measured to evaluate redispersibility. Table 1 shows the results. In addition, each of the electrorheological fluids was placed in a double cylindrical rotary viscometer with a coaxial electric field, and the inner / outer cylinder gap was 1.0 mm,
The shear stress value (initial value) and the current density (initial value) flowing when an external AC electric field of 4000 V / mm (frequency: 50 Hz) was applied under the conditions of a shear rate of 400 s to ¹ and a temperature of 25 ° C. were measured. Furthermore, 4000 V / mm
The shear stress value (value after 3 days) and the current density (value after 3 days) after continuous operation of the viscometer at 25 ° C. for 3 days with the external electric field applied were measured, and the aging of the electrorheological fluid was stabilized. The sex was examined. Table 1 shows the results.

[0074]

[Table 1]

As is clear from Table 1, the electrorheological fluids (1) to (10) of the present invention generate a large shear stress even when a relatively weak electric field is applied, and the current density flowing at that time is reduced. It was excellent in current characteristics that it was small, was excellent in stability of generated shear stress and current density with time, and was not only low in viscosity in a state where an electric field was not applied, but also excellent in dispersion stability and redispersibility.

The electrorheological fluids (1), (3) to (7) and (10) are the same as the comparative fluid (1) using the same dispersing phase and dispersing medium but without additives, and the silicone polymerizable monomer. Comparative fluid (3) using copolymer (8) lacking monomer (A) as an additive, and comparison using copolymer (9) lacking polymerizable monomer (B) as an additive Compared with the fluid (4), the comparative fluid (5) and the comparative fluid (6) using fine particles of copolymerized styrene and divinylbenzene, it was found that the dispersion stability and the redispersibility were greatly superior. In addition, the electrorheological fluids (1), (3) to (7) and (10) of the present invention were compared with the comparative fluid (7) using an amino-modified silicone as an additive, which had poor current characteristics and redispersibility. It was found that the current characteristics were excellent, and the dispersion stability and redispersibility were also improved.

It has been found that the electrorheological fluid (2) has much higher dispersion stability and redispersibility than the comparative fluid (2) using the same dispersing phase and dispersion medium and no additive. Further, the electrorheological fluid (8) was superior to the comparative fluid (8), and the electrorheological fluid (9) was superior to the comparative fluid (9) in both dispersion stability and redispersibility.

[0078]

The electrorheological fluid of the present invention generates a large shear stress even when a relatively weak electric field is applied, and has an excellent current characteristic that the current density flowing at that time is small. Excellent density stability over time, low initial viscosity when no electric field is applied, and dispersion stability (the ability to maintain an electrorheological fluid in a uniform state for a long time without causing the dispersed phase to settle or float). It is particularly excellent in redispersibility (the ability to reproduce the original uniform state with a simple external force after the dispersed phase settles or floats and becomes non-uniform), so engine mounts, clutches, dampers, brakes, It can be effectively used for shock absorbers, actuators, valves and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 33/20 C08L 33/20 71/02 71/02 83/04 83/04 C10M 169/04 C10M 169/04 // (C08L 25/18 (C08L 25/18 83:10) 83:10) (C10M 169/04 (C10M 169/04 107: 50 107: 50 155: 02 155: 02 151: 02) 151: 02) C10N 20:06 C10N 20:06 Z 30:02 30:02 30:04 30:04 40:14 40:14 (72) Inventor Minoru Kobayashi 1-25-12 Kannondai, Tsukuba, Ibaraki Pref. References JP-A-3-192195 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/04 C08L 83/07 C08L 83/10 B01J 13/00 C08L 25/18

Claims (3)

(57) [Claims] 1. An electrorheological fluid containing a dispersed phase composed of dielectric particles having an average particle diameter of 1 to 50 μm, a dispersion medium composed of a silicon-based insulating liquid, and an additive. A structural unit (a) represented by the formula-(SiR ¹ R ² O)-(wherein R ¹ and R ² are each independently an alkyl group or an aryl group) and / or a general formula (R ³ ₃ SiO) ₃ Si— (wherein, R ³ is an alkyl group or an aryl group.) A silicon-based polymer having a structural unit (b) as a main structural unit and an average molecular weight of 400 or more.
Double bond monomer (A) 3 to 70 wt% with the general formula _{^{- (R 4 -O) n -}} ( where, wherein R4 is an alkylene group having 2 to 4 carbon atoms, n represents 4 or more . a number structural unit represented by) (c) and / or the general formula ^{_{- (CH 2 -CR 5 X)}} - ( provided that wherein R ⁵ is hydrogen or methyl, X is -
CN or —COOR ⁶ , wherein R ⁶ is an alkyl group having 1 to 4 carbon atoms. A) a monomer having a polymerizable double bond having an average molecular weight of 400 or more and having a structural unit (d) represented by the following formula (d) as a main structural unit: 0.5 to 40% by weight;
And a polymerizable double bond other than the monomers (A) and (B)
Monomer (C) 0 to 90 wt% with (where the monomer (A), (B) the total of and (C) is 100 wt%.) By polymerizing a monomer component consisting of An electrorheological fluid, wherein the obtained copolymer (I) is used in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the dispersed phase. 2. The electrorheological fluid according to claim 1, wherein the copolymer (I) is obtained by polymerization in an alcohol-based solvent. 3. The dielectric particles serving as a dispersed phase are sulfonic acid group-containing polystyrene-based polymer particles.
An electrorheological fluid according to item 1.