JP3071002B2 - Electrorheological fluid composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an electrorheological fluid composition. More specifically, an electrorheological fluid composition that generates a large shear stress by applying a relatively weak electric field, has a small current density flowing at that time, and has excellent stability over time of the generated shear stress and current density. It is about.

[0002]

2. Description of the Related Art An electrorheological fluid is, for example, a fluid obtained by dispersing and suspending solid particles in an electrically insulating dispersion medium, and its rheological or flow properties are changed by applying an electric field change to a viscoplastic fluid. Is generally known as a fluid exhibiting the so-called Winslow effect, in which the viscosity significantly increases when an external electric field is applied, and a large shear stress is induced. Since this Winslow effect has the characteristic of quick response, the electrorheological fluid is used for torque transmitting actuators such as clutches and brakes,
Applications to control actuators such as engine mounts, dampers, valves, etc., and electrorheological fluid ink jets have been attempted.

[0003] Conventionally, as an electrorheological fluid composition, cellulose, starch, soybean casein, silica gel, polystyrene ion exchange resin, crosslinked polyacrylate, etc. in insulating oils such as silicone oil, diphenyl chloride, and trans oil. Are known in which solid particles are dispersed.

However, an electrorheological fluid composition using cellulose, starch or soybean casein as a disperse phase has a problem that the shear stress obtained when an electric field is applied is small. The electrorheological fluid composition used as the above has a problem in that a shearing stress sufficient for practical use is not induced only by applying a relatively weak electric field.

An electrorheological fluid composition using an alkali metal salt type ion exchange resin of polystyrene sulfonic acid, which is one of polystyrene ion exchange resins, as a dispersed phase has a large shear stress even when a relatively weak electric field is applied. However, there was a problem that the current density flowing at that time was large and the generated shear stress and current density were poor in stability over time.

[0006] We have prepared a dispersed phase comprising a sulfonated polymer obtained by polymerizing a monomer mixture containing a vinyl aromatic compound and a polyvinyl compound as essential components and further adding other vinyl compounds as required, and sulfonating the resulting mixture. The performance of an electrorheological fluid in which particles were dispersed in an electrically insulating dispersion medium was evaluated. As a result, it was found that an improved performance was obtained by devising the method in the polymerization step of the monomer mixture.
That is, in the polymerization of the monomer mixture, the polymerization rate is 30.
The polymerization is carried out at a temperature of less than 80 ° C. until reaching a range of not less than 80% by weight and less than 80% by weight, and thereafter, the conversion is 99.8% by weight.
By conducting polymerization at a temperature of 80 ° C or higher until the above is reached, a large shear stress is generated even when a relatively weak electric field is applied, the current density flowing at that time is small, and the generated shear stress value and current density are stable with time. It has been found that an electrorheological fluid having excellent properties can be obtained. (Japanese Patent Application No. 3-
163135) However, when water-soluble polymers such as polyvinyl alcohol, methylcellulose, and sodium polyacrylate are used as suspending agents in the aqueous suspension polymerization of the monomer mixture, the water-soluble polymers are sulfonated and The electrorheological fluid composition, which remains in the sulfonated polymer particles even after subsequent washing and is used as dispersed phase particles, generates a large shear stress even when a relatively weak electric field is applied, and the current flowing at that time Although the density was small, it was found that there was a problem that the generated shear stress value and the current density were poor in stability over time.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of conventional electrorheological fluid compositions. Therefore, an object of the present invention is to generate a large shear stress even when a relatively weak electric field is applied, the current density flowing at that time is small, and the electro-rheological property is particularly excellent in the stability of the generated shear stress and current density over time. It is to provide a fluid composition.

[0008]

The present invention relates to a monomer mixture (A) comprising a vinyl aromatic compound (a) and a polyvinyl compound (b) as essential components, and optionally adding another vinyl compound (c). ) Is subjected to aqueous suspension polymerization to synthesize a polymerized crosslinked product (I), and then the dispersed phase particles comprising a sulfonated polymer obtained by sulfonating the aromatic ring present in the polymerized crosslinked product (I) are subjected to electrical insulation. It is a composition dispersed in a dispersion medium, and is an inorganic fine particle which is hardly soluble in neutral water and is soluble in acidic water during aqueous suspension polymerization of the monomer mixture (A). Particle size 0.0
The present invention relates to an electrorheological fluid composition using inorganic fine particles of 1 to 1 μm and a suspending aid as a suspending agent. The shape of the dispersed phase particles of the electrorheological fluid is preferably spherical. The average particle size of the dispersed phase particles is in the range of 1 to 50 μm from the balance between the generated shear stress and the dispersion stability (the ability to maintain the electrorheological fluid uniformly for a long time without causing the dispersed phase particles to settle or float). Preferably, there is. In the present invention in which aqueous suspension polymerization is used in the production of the polymerized crosslinked product (I) as an intermediate of the dispersed phase particles composed of the sulfonated polymer, the droplets of the monomer mixture are introduced into the suspension polymerization system before the start of polymerization. The average particle size and shape of the dispersed phase particles composed of a sulfonated polymer by regulating the particle size of the 1 ~ 50μ suitable for the dispersed phase particles
m can easily be set in the range and shape.

The sulfonated polymer used as the dispersed phase particles in the electrorheological fluid composition of the present invention is obtained by sulfonating the polymer crosslinked product (I). As a suspending agent for aqueous suspension polymerization, it is necessary to carry out polymerization using inorganic fine particles which are sparingly soluble in neutral water and soluble in acidic water.

The use of inorganic fine particles that are sparingly soluble in neutral water and soluble in acidic water as a suspending agent makes it possible to suppress the formation of aggregates in the aqueous suspension polymerization of the monomer mixture (A) and to stabilize it. As a result, a crosslinked polymer (I) suitable for the present invention can be obtained. In addition, since the inorganic fine particles used in the present invention are easily removed during the sulfonation process, the solid content of the polymerized crosslinked product (I) taken out from the suspension polymerization system can be simply dried without washing to obtain the next sulfonate. A dispersed phase particle composed of a sulfonated polymer suitable for the present invention can be easily obtained. Therefore, the present invention is also preferable from the viewpoint of simplifying the manufacturing process of the electrorheological fluid.

When the aqueous suspension polymerization of the monomer mixture (A) is carried out using inorganic fine particles soluble in neutral water as a suspending agent, the suspension becomes unstable during the polymerization, causing agglomeration and the like, resulting in polymerization crosslinking. My body is not stable. In the present invention, neutral means a range of pH 6 to 8, as is well known, and a pH less than 6 is called acidic.

When the aqueous suspension polymerization of the monomer mixture (A) is carried out using a water-soluble polymer such as polyvinyl alcohol, methylcellulose or sodium polyacrylate as a suspending agent, A problem arises in that the shear stress value and the current density of the electrorheological fluid using the polymerized crosslinked sulfonated particles as the dispersed phase particles have poor stability over time.

The inorganic fine particles which can be used in the suspension of the present invention are not particularly limited as long as they are hardly soluble in neutral water and dissolved in acidic water.
Examples thereof include poorly soluble phosphates such as hydroxyapatite, and inorganic salts such as aluminum hydroxide, calcium sulfate, barium carbonate, magnesium carbonate, and calcium carbonate, and one or more of these can be used. Considering the ease of handling during suspension polymerization, the use of a sparingly soluble phosphate is preferred.

The average particle size of the inorganic fine particles used in the present invention is not particularly limited as long as the particles do not impair the handling properties. However, the monomer droplets as a suspending agent and the resulting polymer crosslinked product ( The range of 0.01 to 1 μm is preferred from the viewpoint of the dispersion stabilizing effect of I) and the performance as an electrorheological fluid when the finally obtained sulfonated polymer is used as dispersed phase particles in an electrorheological fluid composition. If the average particle diameter of the inorganic fine particles is less than 0.01 μm or more than 1 μm, the suspension system becomes unstable, and only an electrorheological fluid having insufficient shear stress and insufficient current characteristics may be obtained.

These inorganic fine particles can be used by appropriately adjusting the composition and amount thereof so that the particle size of the obtained polymerized crosslinked product (I) is in the range of 1 to 50 μm.

The amount of the inorganic fine particles used is preferably in the range of 1 to 20 parts by weight based on 100 parts by weight of the monomer mixture (A). If the amount is less than 1 part by weight, the suspension becomes unstable. If the amount exceeds 20 parts by weight, a uniform dispersion cannot be obtained. In any case, a stable polymerized crosslinked product (I) may not be obtained. .

In order to keep the suspension system stable, it is preferable to carry out the polymerization by adding a surfactant as a suspending aid.

The suspension aid can be selected from anionic surfactants, nonionic surfactants, amphoteric surfactants, and the like. Anionic surfactants can be used because of the stability of the suspension polymerization reaction system. It is preferable to use an agent. Examples of such anionic surfactants include sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkylnaphthalenesulfonate, dialkylsulfosuccinate, polyoxyethylene alkylphenyl ether sulfate, and the like. The surfactant preferably has a molecular weight of 2000 or less.

It is preferable to use the suspension aid in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the monomer mixture (A).

In the present invention, it is necessary that the monomer mixture (A) contains the vinyl aromatic compound (a),
Vinyl aromatic compound (a) usable in the present invention
Examples thereof include vinyl aromatic hydrocarbons such as styrene, vinylnaphthalene, vinylanthracene, and vinylphenanthrene; monoalkylstyrene compounds such as methylstyrene, ethylstyrene, propylstyrene, butylstyrene, pentylstyrene, and hexylstyrene; dimethylstyrene, diethyl Styrene, dipropyl styrene, methyl ethyl styrene, methyl propyl styrene,
Dialkylstyrene compounds such as methylhexylstyrene, ethylbutylstyrene, ethylpropylstyrene, ethylhexylstyrene and propylbutylstyrene; trimethylstyrene, triethylstyrene, tripropylstyrene, methyldiethylstyrene, dimethylethylstyrene, methylethylpropylstyrene, methyldipropyl Trialkylstyrene compounds such as styrene, dimethylpropylstyrene, ethyldipropylstyrene and diethylpropylstyrene; vinylmonoalkylnaphthalene compounds such as vinylmethylnaphthalene, vinylethylnaphthalene and vinylpropylnaphthalene; vinyldimethylnaphthalene, vinyldiethylnaphthalene, vinyldivinyl Vinyl dialky such as propylnaphthalene and vinylmethylethylnaphthalene Naphthalene compounds; vinyltrialkylnaphthalene compounds such as vinyltrimethylnaphthalene, vinyltriethylnaphthalene, vinyltripropylnaphthalene, vinylmethyldiethylnaphthalene, vinyldimethylethylnaphthalene, vinylmethylethylpropylnaphthalene; chlorostyrene, bromostyrene, fluorostyrene, chloromethyl Styrene, chloroethylstyrene, chloropropylstyrene, chlorodimethylstyrene, bromomethylstyrene, bromoethylstyrene,
Halogenated vinyl aromatic compounds such as fluoromethylstyrene, fluoroethylstyrene, vinylchloronaphthalene and vinylbromonaphthalene; methoxystyrene, dimethoxystyrene, trimethoxystyrene, ethoxystyrene, diethoxystyrene, triethoxystyrene,
Propyloxystyrene, dipropyloxystyrene,
Phenoxystyrene, methoxymethylstyrene, methoxyethylstyrene, methoxypropylstyrene, ethoxymethylstyrene, ethoxyethylstyrene, propyloxymethylstyrene, propyloxyethylstyrene, methoxydimethylstyrene, methoxydiethylstyrene, phenoxydimethylstyrene, phenoxydiethylstyrene, methoxy Chlorostyrene, methoxybromostyrene, vinylmethoxynaphthalene, vinyldimethoxynaphthalene, vinylethoxynaphthalene, vinyldiethoxynaphthalene, vinylmethoxymethylnaphthalene,
Vinylmethoxydimethylnaphthalene, vinyldimethoxymethylnaphthalene, vinylmethoxychloronaphthalene,
Examples thereof include alkoxylated or aryloxylated vinyl aromatic compounds such as vinyldimethoxychloronaphthalene, and one or more of these can be used.

In the present invention, it is necessary that the monomer mixture (A) contains the polyvinyl compound (b).
It is preferably in the range of 1 to 20.0 mol%. When the ratio of the polyvinyl compound (b) exceeds 20.0 mol%, sulfonation hardly proceeds, and a large shear stress is obtained when an electric field is applied to an electrorheological fluid composition using the obtained particles. There is a problem that it cannot be performed. Further, when the ratio of the polyvinyl compound (b) is less than 0.1 mol%, a problem may occur that particles adhere to each other when the polymerized crosslinked product obtained by polymerization is sulfonated.

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

In the present invention, the monomer mixture (A) contains the vinyl aromatic compound (a) and the polyvinyl compound (b) as essential components, and the total amount of the compound (a) and the compound (b) is It is preferable to use 50.0 mol% or more of (A).

The monomer mixture (A) in the present invention may contain, if necessary, a vinyl compound (c) other than the vinyl aromatic compound (a) or the polyvinyl compound (b). It is preferably at most mol%. 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, ethyl (meth) acrylate Ester compounds of unsaturated carboxylic acids such as vinyl acetate; vinyl ester compounds of monovalent carboxylic acids such as vinyl acetate and vinyl propionate; unsaturated amide compounds such as (meth) acrylamide, diacetone acrylamide, and methylolated (meth) acrylamide; Derivatives thereof; unsaturated cyanide compounds such as (meth) acrylonitrile and crotonnitrile; unsaturated alcohol compounds such as (meth) allyl alcohol and croton alcohol; unsaturated monobasic acids such as (meth) acrylic acid; and maleic acid Unsaturated dibasic acids such as fumaric acid and itaconic acid; monoester compounds of a monohydric alcohol such as maleic acid monomethyl ester and maleic acid monoethyl ester with an unsaturated dibasic acid; Can be used alone or in combination of two or more.

As the suspension polymerization method in the present invention, a conventionally known method can be used. For example, a monomer mixture (A) in which a dispersion medium and a suspending agent are charged, and a polymerization initiator is dissolved therein with stirring. Is added, and the particle size is regulated using a disperser or a stirrer, and then the polymerization can be carried out in a suspended state.

Examples of the polymerization initiator for the suspension polymerization include benzoyl peroxide, tertiary butyl hydroxy peroxide, cumene peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, tertiary butyl perphthalate, caproyl peroxide. Peroxides such as azobisisobutyronitrile, azobisisobutylamide, 2,2′-azobis (2,4-dimethylmaleronitrile), azobis (α
-Dimethylvaleronitrile), azo compounds such as azobis (α-methylbutyronitrile) and the like, and one or more of these can be used. Especially, it is preferable to use benzoyl peroxide and azobisisobutyronitrile.

As a dispersion medium for suspension polymerization, water is usually used.

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

It is preferable that the particle size control and the polymerization are carried out in a nitrogen atmosphere.

The suspension polymerization is usually carried out at a temperature in the range of 50 ° C. to 100 ° C. for about 2 to 30 hours, and particularly at 80 ° C. until the polymerization rate reaches a range of 30% by weight or more and less than 80% by weight. Temperature, preferably from 50 ° C. to 80 ° C. until the conversion reaches a range of from 40% by weight to less than 70% by weight.
It is preferable to polymerize at a temperature of less than about 0.3 to 10 hours, and then perform the polymerization at a temperature of 80 ° C. or more for about 1 to 20 hours until the polymerization rate becomes 99.8% by weight or more.

The crosslinked polymer (I) used in the present invention comprises:
A substantially non-porous polymer cross-linked product called a gel type may be used, or a known porous forming agent that imparts porosity to the polymer cross-linked product obtained during polymerization, for example, a swellable organic solvent,
It may be a porous polymer crosslinked product obtained by polymerizing a monomer mixture in the presence of a non-swellable organic solvent, a linear polymer soluble in a monomer, or a mixture thereof.

The particles of the sulfonated polymer constituting the dispersed phase particles used in the present invention are obtained by sulfonating the polymerized crosslinked product (I) obtained by the above-mentioned polymerization method, and appropriately pulverizing or granulating as necessary. Is obtained.

As the sulfonating agent used for sulfonating the aromatic ring present in the crosslinked polymer (I) in the present invention, a known sulfonating agent may be used, for example, sulfuric acid, fuming sulfuric acid, chloroform. Sulfuric acid and the like can be mentioned, and one or more of these can be used.

When sulfuric acid is used as the main component of the sulfonating agent, the sulfonation is usually performed at a temperature within the range of 60 to 100 ° C. for about 0.3 to 100 hours. Sulfuric acid
It is preferable to use 500 parts by weight or more based on 100 parts by weight of the polymer crosslinked product (I).

When chlorosulfuric acid is used as the main component of the sulfonating agent, sulfonation is usually carried out at a temperature in the range of -20 to 100 ° C. for about 0.3 to 100 hours.
As preferred conditions, the polymer crosslinked product (I) is kept at 70 ° C. or more for 30 minutes or more in the presence of chlorosulfuric acid, or the polymer crosslinked product (I) is kept at −20 ° C. or more and less than 70 ° C. After holding at a temperature in the range of 0.3 to 30 hours, there may be mentioned one that is further held at a temperature of 70 ° C. or more for 30 minutes or more. Above all, a method considering the ease of controlling the sulfonation reaction is preferable. The chlorosulfuric acid is preferably used in a proportion of 500 parts by weight or more based on 100 parts by weight of the polymer crosslinked product (I).

When fuming sulfuric acid is used as the sulfonating agent, sulfonation is usually carried out at a temperature within the range of -20 to 100 ° C. for about 0.3 to 100 hours. (I) in the presence of fuming sulfuric acid at 70
After holding the polymer crosslinked product (I) at a temperature of -20 ° C or more and less than 70 ° C for 0.3 to 30 hours in the presence of fuming sulfuric acid, and then at 70 ° C or more At a temperature of 30 minutes or more. Above all, a method considering the ease of controlling the sulfonation reaction is preferable. The fuming sulfuric acid is preferably used in a proportion of 150 parts by weight or more based on 100 parts by weight of the polymer crosslinked product (I).

The sulfonation reaction is carried out without a solvent, in the presence of a solvent that does not swell with respect to the polymerized crosslinked product (I), or in the presence of a solvent that is swellable with respect to the polymerized crosslinked product (I). Can be.

The solvent which does not swell with respect to the polymer crosslinked product (I) may be any solvent which does not swell the polymer crosslinked product (I) and is inert to the sulfonating agent. And aliphatic hydrocarbons such as ligroin. The solvent which is swellable with respect to the polymer crosslinked product (I) may be any solvent which swells the polymer crosslinked product (I) and is inactive with respect to the sulfonating agent. For example, ethylene dichloride, trichloroethylene, tetrachloroethane, Examples thereof include nitrobenzene, propylene chloride, and carbon tetrachloride.

The use amount of these solvents is preferably within a range of 1,000 parts by weight or less based on 100 parts by weight of the polymer crosslinked product (I).

In the sulfonation reaction, for example, a transition metal salt such as mercury sulfate or silver sulfate or a pentavalent phosphorus compound such as phosphorus pentoxide can be used in combination with a sulfonating agent. The particles of the sulfonated polymer obtained by sulfonating the polymerized crosslinked product (I) are separated from the sulfonating agent and then sufficiently removed with a large amount of water in order to remove the acid and the like remaining in the particles. It is good to wash. Then, if necessary, the cation of the sulfonic acid group can be changed from a proton to a suitable cation species by a method such as neutralization or ion exchange.

The sulfonic acid group referred to in the present invention is a cation which releases a cation in the presence of a polar solvent such as water and turns itself into a sulfonic acid ion, and releases a cation in the presence of a polar solvent such as water. There is no particular limitation.

The cation of the sulfonic acid group present in the sulfonated polymer constituting the dispersed phase particles used in the present invention includes, for example, hydrogen; an alkali metal such as lithium, sodium and potassium; and an alkali metal such as magnesium and calcium. Earth metals; Group IIIA metals such as aluminum;
Group IVA metals such as tin and lead; cationic species such as transition metals such as zinc, iron, copper, cobalt and nickel; ammonium;
Organic quaternary ammonium, pyridinium, guadinium and the like can be mentioned, and one or more of these can be used.

The dispersed phase particles used in the present invention are preferably those obtained by adding a small amount of water to the above-mentioned sulfonated polymer particles. In the electrorheological fluid composition of the present invention, since a small amount of water is contained in the dispersed phase particles, a large shear stress is induced when an electric field is applied.

In the present invention, the water in the dispersed phase particles is preferably 20 parts by weight or less based on 100 parts by weight of the particles. When water exceeds 20 parts by weight, the dispersed phase particles adhere to each other, or the prepared electrorheological fluid composition has a reduced insulating property, so that a large current flows when an electric field is applied, which is not preferable. .

The electrically insulating dispersion medium that can be used in the present invention is not particularly limited. For example, silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane; liquid paraffin, decane, dodecane, methylnaphthalene, dimethylnaphthalene , Ethylnaphthalene, biphenyl, decalin, partially hydrogenated hydrocarbons such as triphenyl; ether compounds such as biphenyl ether; chlorobenzene, dichlorobenzene, trichlorobenzene, bromobenzene, dibromobenzene, chloronaphthalene, dichloronaphthalene, bromonaphthalene, Chlorobiphenyl, dichlorobiphenyl, trichlorobiphenyl, bromobiphenyl, chlorodiphenylmethane, dichlorodiphenylmethane, trichlorodiphenylmethane, bromodiph Halogenated hydrocarbons such as chloromethane, chlorodecane, dichlorodecane, trichlorodecane, trichlorodecane, bromodecane, chlorododecane, dichlorododecane, and bromododecane; halogenated diphenyl ether compounds such as chlorodiphenyl ether, dichlorodiphenyl ether, trichlorodiphenyl ether, and bromodiphenyl ether; And demnum (manufactured by Daikin Industries, Ltd.); ester compounds such as dioctyl phthalate, trioctyl trimellitate and dibutyl sebacate; and the like. The above can be used. Among them, silicone oil and hydrocarbon are preferred.

The electrorheological fluid composition of the present invention is obtained by dispersing the above-mentioned dispersed phase particles in an electrically insulating dispersion medium, and the ratio of the dispersed phase particles to the insulating dispersion medium in the composition is 100% by weight of the former. It is preferred that the latter be in the range of 50 to 500 parts by weight based on parts. When 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 composition 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.

In the present invention, for example, a surfactant, a polymer dispersant, and a polymer thickener may be used to improve the dispersibility of the dispersed phase particles in the dispersion medium, adjust the viscosity of the electrorheological fluid composition, or increase the shear stress. Various additives such as agents can be added to the composition.

[0048]

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.

[0049]

Example 1 Into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, 1.2 liters of water was charged, into which 30 g of calcium triphosphate having an average particle diameter of 0.6 μm and dodecylbenzene sulfone were added. After adding and mixing 0.05 g of sodium acid, 260 g of styrene, 40 g of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) and 10 g of benzoyl peroxide Was added. Thereafter, the content in the flask was dispersed at a stirring speed of 5000 rpm using a disperser to control the particle size. Next, after polymerization at 75 ° C. for 1 hour, the polymerization temperature was further raised to 95 ° C. and heated for 4 hours. After completion of the reaction, the obtained solid was filtered and washed with a hot air drier at 80 ° C. for 12 hours without washing with water.
That. ｝ 315 g was obtained.

A 2-liter four-neck separable flask equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (1), and the reaction vessel was cooled to 0 ° C. in an ice bath. 500 g of fuming sulfuric acid of 25% by weight was added thereto to obtain a uniform dispersion. After stirring for 12 hours, the ice bath was removed, and the mixture was heated and stirred at 80 ° C. for 3 hours to carry out a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. The obtained solid was neutralized with 330 ml of a 10% by weight aqueous sodium hydroxide solution, and then sufficiently washed with water. Next, it is dried at 80 ° C. for 10 hours using a vacuum drier, and the dispersed phase particles composed of 102 g of a spherical sulfonated polymer are hereinafter referred to as dispersed phase particles (1). I got｝.

The average particle diameter of the obtained dispersed phase particles (1) was measured by using a particle size distribution analyzer (SALD-1 manufactured by Shimadzu Corporation).
000) was 10 μm.
The ion exchange capacity of the dispersed phase particles (1) was determined by neutralization titration and elemental analysis.
It was 8 mg equivalent / g, and 5.7 mg equivalent / g by elemental analysis. When the water content in the dispersed phase particles (1) was measured using a Karl Fischer moisture meter (MPS-3P, manufactured by Kyoto Electronics Industry Co., Ltd.), it was 2.5 parts by weight. (Measurement of the average particle diameter, ion exchange capacity, and water content in the following Examples and Comparative Examples was performed in the same manner as in this example.)
30 g of the obtained dispersed phase particles (1) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-20CS (dimethyl silicon oil manufactured by Shin-Etsu Chemical Co., Ltd.), and the electrorheological fluid composition of the present invention (hereinafter referred to as “the composition”) was used. A fluid composition (1)
That. I got｝.

[0052]

EXAMPLE 2 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and 40 g of calcium triphosphate having an average particle diameter of 0.6 μm and dodecylbenzene sulfone were added thereto. After adding and mixing 0.09 g of sodium acid, a mixture of 284 g of styrene, 16 g of industrial divinylbenzene used in Example 1 and 5 g of azobisisobutyronitrile was further added. After that, 800
The contents in the flask were dispersed at a stirring speed of 0 rpm to control the particle size. Next, after polymerization at 65 ° C. for 2 hours, the polymerization temperature was further increased to 90 ° C., and the mixture was heated for 6 hours. After the completion of the reaction, the obtained solid was separated by filtration and dried at 80 ° C. for 12 hours using a hot air drier without washing with water. That. ｝ 326 g was obtained.

In a 2-liter four-neck separable flask equipped with a stirrer, a thermometer and a dropping funnel, 50 g of the crosslinked polymer (2) was charged, and the reaction vessel was cooled to 0 ° C. in an ice bath. Thereto was added 500 g of chlorosulfuric acid to obtain a uniform dispersion. After stirring for 12 hours, the ice bath was removed,
The mixture was heated and stirred at 80 ° C. for 3 hours to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. After neutralizing the obtained solid with 310 ml of a 10% by weight aqueous sodium hydroxide solution,
Washed thoroughly with water. Then, using a vacuum dryer, 8
After drying at 0 ° C. for 10 hours, 94 g of a dispersed phase particle composed of a spherical sulfonated polymer (hereinafter referred to as dispersed phase particles (2))
That. I got｝.

The average particle size of the obtained dispersed phase particles (2) was measured using a particle size distribution analyzer and found to be 5 μm. When the ion exchange capacity of the dispersed phase particles (2) was quantified by neutralization titration and elemental analysis, it was 5.5 mg equivalent / g by neutralization titration and 5.5 mg equivalent / g by elemental analysis. The water content in the dispersed phase particles (2) was measured using a Karl Fischer moisture meter, and was 2.4 parts by weight.

30 g of the obtained dispersed phase particles (2) were mixed and dispersed in 70 g of THERM S900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.) to obtain an electrorheological fluid composition of the present invention. ｛Hereinafter, this is referred to as a fluid composition (2). I got｝.

[0056]

Example 3 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and 60 g of barium carbonate having an average particle diameter of 0.08 μm and dodecylbenzene sulfone were added thereto. After adding and mixing 0.03 g of sodium acid, styrene 140 was further added.
g, 133 g of methoxystyrene, 27 g of the same industrial divinylbenzene as used in Example 1 and 5 g of azobisisobutyronitrile were added. Thereafter, the content in the flask was dispersed at a stirring speed of 750 rpm using a disperser to control the particle size. Next, after polymerization at 70 ° C. for 1 hour, the polymerization temperature was further raised to 90 ° C. and heated for 6 hours. The obtained solid was filtered and washed with a hot air drier at 80 ° C. for 12 hours without being washed with water. The resulting polymer was a spherical polymer crosslinked product (hereinafter referred to as polymer crosslinked product (3)). ｝ 330 g was obtained.

A 2-liter four-neck separable flask equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (3), and the reaction vessel was cooled to 0 ° C. in an ice bath. Thereto was added 500 g of chlorosulfuric acid to obtain a uniform dispersion. After stirring for 12 hours, the ice bath was removed,
The mixture was heated and stirred at 80 ° C. for 1 hour to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. The obtained solid was neutralized with a 10% by weight aqueous sodium hydroxide solution (310 ml), and then sufficiently washed with water. Then, using a vacuum dryer, 80
After drying at 10 ° C. for 10 hours, the dispersed phase particles composed of 84 g of a spherical sulfonated polymer (hereinafter referred to as “dispersed phase particles (3)”). I got｝.

When the average particle size of the obtained dispersed phase particles (3) was measured using a particle size distribution analyzer, it was 25 μm. When the ion exchange capacity of the dispersed phase particles (3) was determined by a neutralization titration method and an elemental analysis method, it was 5.4 mg equivalent / g by the neutralization titration method and 5.3 mg equivalent / g by the elemental analysis method. The water content in the dispersed phase particles (3) was measured using a Karl Fischer moisture meter, and was 2.4 parts by weight.

30 g of the obtained dispersed phase particles (3) were mixed and dispersed in 70 g of THERM S900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.) to obtain an electrorheological fluid composition of the present invention. ｛Hereinafter, this is referred to as a fluid composition (3). I got｝.

[0060]

Example 4 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and 10 g of calcium triphosphate having an average particle diameter of 0.6 μm and dodecylbenzene were added thereto. After adding and mixing 0.5 g of sodium sulfonate, a mixture composed of 260 g of styrene, 40 g of industrial divinylbenzene used in Example 1 and 10 g of benzoyl peroxide was further added. Thereafter, the content in the flask was dispersed at a stirring speed of 700 rpm using a disperser to control the particle size. Next, after polymerization at 75 ° C. for 1 hour, the polymerization temperature was further raised to 95 ° C. and heated for 4 hours. After completion of the reaction, the obtained solid was separated by filtration and dried at 80 ° C. for 12 hours using a hot-air drier without washing with water. That. ｝ 295 g was obtained.

A 2-liter four-neck separable flask equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (4) and 500 g of 98% by weight concentrated sulfuric acid.
The mixture was heated and stirred at 0 ° C. for 24 hours to carry out a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. After neutralizing the obtained solid with 250 ml of a 10% by weight aqueous sodium hydroxide solution,
Washed thoroughly with water. Then, using a vacuum dryer, 8
After drying at 0 ° C. for 10 hours, 87 g of dispersed phase particles composed of a spherical sulfonated polymer (hereinafter referred to as dispersed phase particles (4))
That. I got｝. The average particle diameter of the obtained dispersed phase particles (4) was measured using a particle size distribution analyzer, and was found to be 35.
μm. When the ion exchange capacity of the dispersed phase particles (4) was determined by a neutralization titration method and an elemental analysis method, the neutralization titration method was 4.6 mg equivalent / g, and the elemental analysis method was 4.7.
mg equivalent / g. When the water content in the dispersed phase particles (4) was measured using a Karl Fischer moisture meter,
It was 2.5 parts by weight.

30 g of the obtained dispersed phase particles (4) were mixed with 70 g of Shin-Etsu silicone oil KF96-20CS (dimethyl silicon oil manufactured by Shin-Etsu Chemical Co., Ltd.).
Dispersed, the electrorheological fluid composition of the present invention (hereinafter referred to as fluid composition (4)). I got｝.

[0063]

Comparative Example 1 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and charged with Kuraray Povar PVA-205 (trade name).
Add 16.0 g of Kuraray's polyvinyl alcohol)
After dissolution, a mixture consisting of 260 g of styrene, 40 g of the same industrial-use divinylbenzene used in Example 1 and 10 g of benzoyl peroxide was further added. afterwards,
The contents in the flask were dispersed at a stirring speed of 5000 rpm using a disperser to control the particle size. Next, after polymerization at 75 ° C. for 1 hour, the polymerization temperature was further raised to 95 ° C. and heated for 4 hours. The solid obtained was filtered and washed with water without drying at 80 ° C. for 12 hours using a hot air drier to obtain a spherical polymer crosslinked product (hereinafter referred to as polymer crosslinked product (5)).
That. 286 g were obtained.

In a 2-liter four-neck separable flask equipped with a stirrer, a thermometer and a dropping funnel, 50 g of the crosslinked polymer (5) was charged, and the reaction vessel was cooled to 0 ° C. in an ice bath. 500 g of fuming sulfuric acid of 25% by weight was added thereto to obtain a uniform dispersion. After stirring for 12 hours, the ice bath was removed, and the mixture was heated and stirred at 80 ° C. for 3 hours to carry out a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. The obtained solid was neutralized with 330 ml of a 10% by weight aqueous sodium hydroxide solution, and then sufficiently washed with water. Next, it is dried at 80 ° C. for 10 hours using a vacuum dryer, and comparative dispersed phase particles composed of 119 g of a spherical sulfonated polymer (hereinafter referred to as comparative dispersed phase particles (1)). I got｝.

The average particle size of the obtained comparative dispersed phase particles (1) was measured using a particle size distribution analyzer.
m. The ion exchange capacity of the comparative dispersed phase particles (1) was determined by neutralization titration and elemental analysis. The neutralization titration was 5.7 mg equivalent / g, and the elemental analysis was 5.5.
It was 7 mg equivalent / g. The water content in the comparative dispersed phase particles (1) was measured using a Karl Fischer moisture meter, and was 2.5 parts by weight.

30 g of the obtained comparative dispersed phase particles (1) were mixed with 70 g of Shin-Etsu silicone oil KF96-20CS (dimethyl silicon oil manufactured by Shin-Etsu Chemical Co., Ltd.).
An electrorheological fluid composition for comparison, which is hereinafter referred to as a comparative fluid composition (1). I got｝.

[0067]

Comparative Example 2 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and charged with Kuraray Povar PVA-205 (trade name).
After adding and dissolving 8.0 g of Kuraray's polyvinyl alcohol, a mixture of 284 g of styrene, 16 g of industrial divinylbenzene used in Example 1 and 5 g of azobisisobutyronitrile was further added. . Thereafter, the contents in the flask were dispersed at a stirring speed of 8000 rpm using a disperser to control the particle size. Then 6
After polymerization at 5 ° C. for 2 hours, the polymerization temperature was further raised to 90 ° C. and heated for 6 hours. After completion of the reaction, the obtained solid was filtered and washed with a hot air drier without washing with water.
After drying at 12 ° C. for 12 hours, a spherical polymer crosslinked product (hereinafter referred to as polymer crosslinked product (6)). ｝ 291 g were obtained.

A 2-liter four-neck separable flask equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (6), and the reaction vessel was cooled to 0 ° C. in an ice bath. Thereto was added 500 g of chlorosulfuric acid to obtain a uniform dispersion. After stirring for 12 hours, the ice bath was removed,
The mixture was heated and stirred at 80 ° C. for 3 hours to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. After neutralizing the obtained solid with 310 ml of a 10% by weight aqueous sodium hydroxide solution,
Washed thoroughly with water. Then, using a vacuum dryer, 8
After drying at 0 ° C. for 10 hours, comparative dispersed phase particles composed of 102 g of a spherical sulfonated polymer (hereinafter referred to as comparative dispersed phase particles (2)). I got｝.

The average particle size of the obtained comparative dispersed phase particles (2) was measured using a particle size distribution analyzer.
Met. When the ion exchange capacity of the comparative dispersed phase particles (2) was quantified by neutralization titration and elemental analysis, the neutralization titration was 5.5 mg equivalent / g, and the elemental analysis was 5.6.
mg equivalent / g. The water content in the comparative dispersed phase particles (2) was measured using a Karl Fischer moisture meter, and was 2.4 parts by weight.

30 g of the obtained comparative dispersed phase particles (2) were mixed and dispersed in 70 g of THERM S900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.), and an electrorheological fluid composition for comparison was prepared. The following is a comparative fluid composition (2)
That. I got｝.

[0071]

Comparative Example 3 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and charged with Kuraray Povar PVA-205 (trade name).
After adding and dissolving 1.6 g of Kuraray's polyvinyl alcohol, a mixture consisting of 140 g of styrene, 133 g of methoxystyrene, 27 g of industrial divinylbenzene used in Example 1 and 5 g of azobisisobutylnitrile was further added. . Then, using a disperser, 700r
The contents in the flask were dispersed at a stirring speed of pm to control the particle size. After polymerizing at 70 ° C. for 1 hour, the polymerization temperature was further raised to 90 ° C. and heated for 6 hours. The solid obtained was filtered and washed with hot air using a hot air drier without washing.
After drying at 0 ° C. for 12 hours, a spherical polymer crosslinked product (hereinafter referred to as “polymerized crosslinked product (7)”). $ 289 g was obtained.

A 2-liter four-neck separable flask equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (7), and the reaction vessel was cooled to 0 ° C. in an ice bath. Thereto was added 500 g of chlorosulfuric acid to obtain a uniform dispersion. After stirring for 12 hours, the ice bath was removed,
The mixture was heated and stirred at 80 ° C. for 1 hour to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. After neutralizing the obtained solid with 310 ml of a 10% by weight aqueous sodium hydroxide solution,
Washed thoroughly with water. Then, using a vacuum dryer, 8
After drying at 0 ° C. for 10 hours, 98 g of spherical dispersed sulfonated polymer for comparative dispersion phase particles (hereinafter referred to as comparative dispersed phase particles (3)). I got｝.

The average particle size of the obtained comparative dispersed phase particles (3) was measured using a particle size distribution analyzer.
m. When the ion exchange capacity of the comparative dispersed phase particles (3) was quantified by neutralization titration and elemental analysis, the neutralization titration was 5.2 mg equivalent / g, and the elemental analysis was 5.5 mg equivalent / g.
It was 3 mg equivalent / g. The water content in the comparative dispersed phase particles (3) was measured using a Karl Fischer moisture meter and found to be 2.4 parts by weight.

30 g of the obtained comparative dispersed phase particles (3) were mixed and dispersed in 70 g of THERM S900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.), and an electrorheological fluid composition for comparison was prepared. The following is a comparative fluid composition (3)
That. I got｝.

[0075]

Comparative Example 4 1.2 liters of water was charged into a 3 liter four-neck separable flask equipped with a stirrer, a reflux condenser and a thermometer, and charged with Kuraray Povar PVA-205 (trade name).
After 8.0 g of Kuraray's polyvinyl alcohol was added and dissolved, a mixture of 260 g of styrene, 40 g of industrial divinylbenzene used in Example 1, and 10 g of benzoyl peroxide was further added. Then, the content in the flask was dispersed at a stirring speed of 700 rpm using a disperser to control the particle size. Next, after polymerization at 70 ° C. for 1 hour, the polymerization temperature was further raised to 90 ° C. and heated for 6 hours. The solid obtained was filtered off and 2 liters of water 30
The washing and filtration for 2 minutes were repeated twice, and thereafter, the resultant was dried at 80 ° C. for 12 hours using a hot-air drier, and this was hereinafter referred to as a polymer crosslinked product (8). $ 289 g was obtained.

A 2-liter four-neck separable flask equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (8) and 500 g of 98% by weight concentrated sulfuric acid, and heated and stirred at 80 ° C. for 24 hours. A sulfonation reaction was performed. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water / acetone. The solid obtained is 1
After neutralizing with 250 ml of a 0% by weight aqueous sodium hydroxide solution, the resultant was sufficiently washed with water. Next, it is dried at 80 ° C. for 10 hours using a vacuum drier, and comparative dispersed phase particles composed of 88 g of a spherical sulfonated polymer (hereinafter referred to as comparative dispersed phase particles (4)). I got｝.

The average particle size of the obtained comparative dispersed phase particles (4) was measured using a particle size distribution analyzer.
m. When the ion exchange capacity of the comparative dispersed phase particles (4) was quantified by a neutralization titration method and an elemental analysis method, the neutralization titration method was 4.7 mg equivalent / g, and the elemental analysis method was 4.
It was 6 mg equivalent / g. The water content in the comparative dispersed phase particles (4) was measured using a Karl Fischer moisture meter, and was 2.4 parts by weight.

30 g of the obtained comparative dispersed phase particles (4) were mixed with 70 g of Shin-Etsu silicone oil KF96-20CS (dimethyl silicon oil manufactured by Shin-Etsu Chemical Co., Ltd.).
An electrorheological fluid composition for comparison, which is hereinafter referred to as a comparative fluid composition (4). I got｝.

[0079]

Example 5 Each of the fluid compositions (1) to (4) and the comparative fluid compositions (1) to (4) obtained in Examples 1 to 4 and Comparative Examples 1 to 4 was rotated with a coaxial electric field. Put in the viscometer,
Shear stress value (initial value) when an external AC electric field of 4000 V / mm (frequency: 60 Hz) is applied under the conditions of an inner / outer cylinder gap of 1.0 mm, a shear rate of 400 s- ¹ and a temperature of 25 ° C.
The current density (initial value) flowing at that time was measured.

The shear stress (after 14 days) and the current density (after 14 days) after continuous operation of the viscometer at 25 ° C. for 14 days with an external electric field of 4000 V / mm were applied. The fluid composition was measured to determine the stability over time.

The results are shown in Table 1.

[0082]

[Table 1]

The electrorheological fluid has a higher shear stress value obtained when a relatively weak electric field is applied, and has a higher shear stress value, and a lower current density at the time. It is particularly preferable that both the shear stress characteristic and the current characteristic are excellent. Therefore, as a parameter for judging superiority by simultaneously evaluating the shear stress characteristic and the current characteristic, a ratio of a shear stress value obtained when a constant electric field is applied to a current density flowing at that time, that is, (shear stress value) / ( This value is hereinafter referred to as Z value. ｝ Is effective. That is, an electrorheological fluid composition having both excellent shear stress characteristics and current characteristics has a large Z value.

Each of the fluid compositions (1) to (4) and the comparative fluid compositions (1) to (4) was determined from the shear stress value and the current density observed when an electric field of 4000 V / mm was applied. The initial value of the Z value of each fluid composition and 1
The values after 4 days are shown in Table 1.

As is clear from Table 1, the fluid compositions (1) to (4) of the present invention can obtain a large shear stress even when a relatively weak electric field is applied, and the current density flowing at that time is small. The current characteristics were excellent and the shear stress and the current density generated over time were very excellent in stability. In addition, the fluid compositions (1) to (4) of the present invention have an initial Z value of 2.7 or more, and even after 14 days,
The value was 2.7 or more, indicating that the composition was an electrorheological fluid having excellent stability over time in the balance between shear stress characteristics and current characteristics.

On the other hand, comparative fluid compositions (1) and (2)
In the fluid composition of the present invention, the initial Z value was 1.4 and 1.2, which was smaller than that of the fluid composition of the present invention, and was inferior in the balance between shear stress and current density. In addition, the aging stability of the shear stress value and the current density became unmeasurable after one day, and was inferior to the fluid composition of the present invention.

In the comparative fluid compositions (3) and (4), the Z value was 1.9 and 2.2 at the initial stage, which was smaller than that of the fluid composition of the present invention. Inferior in equilibrium. In addition, the comparative fluid composition (3) was inferior in the stability over time of the shear stress and the current density after 3 days, and the comparative fluid composition (4) was unmeasurable after 2 days, which was inferior to the fluid composition of the present invention. .

[0088]

The electrorheological fluid composition of the present invention is very excellent in stability over time such that a large shear stress is obtained even when a relatively weak external electric field is applied and the generated shear stress is maintained for a long period of time. Therefore, it can be effectively used for torque transmitting actuators such as clutches and brakes, control actuators such as engine mounts, dampers and valves, and electrorheological fluid ink jets.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C10N 30:00 40:14 60:10 70:00 Examiner Hiroko Fujiwara (56) References JP-A-3-215597 (JP, A) JP JP-A-62-235301 (JP, A) JP-A-2-189302 (JP, A) JP-A-50-141688 (JP, A) JP-A-5-112608 (JP, A) JP-A-3-192195 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C10M 151/02 C10N 40:14 C08F 2/18

Claims (2)

(57) [Claims] An aqueous suspension polymerization of a monomer mixture (A) containing a vinyl aromatic compound (a) and a polyvinyl compound (b) as essential components and further adding other vinyl compounds (c) as required, to carry out polymerization crosslinking. A composition obtained by synthesizing a polymer (I) and then dispersing dispersed phase particles comprising a sulfonated polymer obtained by sulfonating an aromatic ring present in the polymerized crosslinked product (I) in an electrically insulating dispersion medium. In the case of aqueous suspension polymerization of the monomer mixture (A), the inorganic fine particles are sparingly soluble in neutral water and soluble in acidic water, and have an average particle diameter of 0.01 to 1 μm. An electrorheological fluid composition comprising inorganic fine particles and a suspending agent as a suspending agent. 2. The electrorheological fluid composition according to claim 1, wherein the inorganic fine particles are phosphate.