JP3115674B2 - Method for producing electrorheological fluid composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an electrorheological fluid composition .
It relates to a manufacturing method . 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. And a method for producing the same.

[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-based ion exchange resin, poly (meth) acrylate in insulating oils such as silicone oil, diphenyl chloride, and trans oil. What disperse | distributed solid particles, such as a crosslinked body, is known.

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.

Further, 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 disperse phase has a large shear force even when a relatively weak electric field is applied. Although stress can be obtained, there has been a problem that the current density flowing at that time is large, and the generated shear stress and current density have poor stability over time.

On the other hand, we have disclosed a dispersed phase comprising a sulfonated polymer obtained by sulfonating a polymerized crosslinked product of a monomer mixture containing a vinyl aromatic compound and a polyvinyl compound as essential components and further adding other vinyl compounds as required. Various studies have been made on electrorheological fluids in which particles are dispersed in an electrically insulating dispersion medium. For example, when an aqueous suspension polymerization is used in the polymerization step of the monomer mixture, a molecular weight of 2
When a surfactant of 000 or less is used or inorganic fine particles that are hardly soluble in neutral water and are soluble in acidic water, a large shear stress is generated even when a relatively weak electric field is applied, and the current density flowing at that time is reduced. It has been found that an electrorheological fluid having a small shear stress value and excellent current density stability over time can be obtained (Japanese Patent Application Nos. 3-271191 and 3-271192).

However, in the production of a polymerized crosslinked product by aqueous suspension polymerization of such a monomer mixture, it is necessary to separate the produced polymerized crosslinked product from the suspension and take it out. A crosslinked polymer in the form of a liquid was not obtained, and an electrorheological fluid having the above-mentioned performance was not obtained.

[0008] As a method for removing the crosslinked polymer from the suspension, for example, a filtration method, a centrifugal sedimentation method, and a method of coagulation or sedimentation using a flocculant are known.

[0009] However, the average particle size of the polymer cross-linked material suitably used for the electrorheological fluid is 1 to 50 µm, particularly preferably 3 to 20 µm. In this method, the centrifugal force required for centrifugal sedimentation increased, and solid-liquid separation by these methods was limited. In addition, when a conventionally known polymer coagulant or inorganic fine particles that do not dissolve in acidic water are added and coagulated,
The flocculant remained in the sulfonated polymer particles even after the sulfonation and subsequent washing, or the flocculation effect was insufficient, and the electrorheological fluid using the obtained sulfonated polymer particles was sheared. There is a problem that the temporal stability of the stress value and the current density is poor.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of conventional electrorheological fluid compositions. Accordingly, an object of the present invention is to provide an electrorheological fluid composition that generates a large shear stress even when a relatively weak electric field is applied, the current density flowing at that time is small, and the generated shear stress and the current density are particularly excellent with time stability. Stuff
It is to provide a manufacturing method of.

[0011]

According to the present invention, a monomer mixture (A) containing a vinyl aromatic compound (a) and a polyvinyl compound (b) as essential components and optionally adding another vinyl compound (c) is used. Crosslinked polymer (I) by aqueous suspension polymerization
In the synthesis, and then the polymer crosslinked (I) aromatic rings are dispersed dispersed phase particles consisting of sulfonated polymer obtained by sulfonating in the electrically insulating dispersion medium comprising the composition present in, to a suspension of the polymer crosslinked product obtained by aqueous suspension polymerization (I) after, adding an inorganic compound soluble in acidic water, thereby aggregating the polymer crosslinked body (I), the suspension a method of manufacturing the electro-rheological fluid composition characterized by combining the heavy <br/> if crosslinked body (I) by separating the polymer crosslinked body (I) than in.

[0012]

The shape of the dispersed 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 in a uniform state for a long time without causing the dispersed phase particles to settle or float). Is preferably within the range. When aqueous suspension polymerization is used in synthesizing the polymerized crosslinked product (I) which is an intermediate of the above-mentioned disperse phase particles composed of the sulfonated polymer, the monomer mixture (A) in the suspension polymerization system before the polymerization is started If the particle diameter of the droplets is regulated, the average particle diameter and shape of the dispersed phase particles are preferably 1 to
It can be easily made into a 50 μm spherical shape. The sulfonated polymer used as the dispersed phase particles in the electrorheological fluid composition of the present invention is obtained by sulfonating the polymerized crosslinked product (I). In the present invention, however, the aqueous suspension used in synthesizing the polymerized crosslinked product (I) is used. An inorganic compound dissolved in acidic water is added to the suspension at the end of the suspension polymerization to aggregate the polymerized crosslinked product (I), and then the polymerized crosslinked product (I) is separated from the suspension. By performing aggregation treatment using such a specific inorganic compound,
Step of separating polymerized crosslinked product (I) from suspension (filtration, etc.)
, The workability can be improved.

When an inorganic compound or a polymer flocculant which does not dissolve in acidic water is used, the flocculant effect becomes insufficient or the flocculant remains in the obtained polymerized crosslinked product and is easily formed by sulfonation. Since it cannot be removed, there arises a problem that the temporal stability of the shear stress value and the current density of the electrorheological fluid using the sulfonated polymer as the dispersed phase particles is poor.

In the present invention, the inorganic compound used for aggregating the polymerized crosslinked product (I) is not particularly limited as long as it is dissolved in acidic water.
Metal oxides such as magnesium oxide and zinc oxide; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate;
Sulfates such as aluminum sulfate and calcium sulfate; phosphates such as calcium triphosphate and magnesium triphosphate; and polyaluminum chloride. Among them, poorly soluble and acidic in neutral water such as metal oxides such as calcium oxide, magnesium oxide and zinc oxide, carbonates such as barium carbonate, calcium carbonate and magnesium carbonate, and phosphates such as calcium triphosphate and magnesium triphosphate. Addition of inorganic fine particles soluble in water,
It is preferable because the flocculent particles can be stably aggregated to form floc-like particles of a preferable size, and the crushability of the polymerized crosslinked product (I) after drying can be significantly improved. Therefore, the average particle diameter of the inorganic fine particles used is preferably 0.01 to 20 μm. Average particle size of inorganic fine particles is 0.01μ
If it is less than m or more than 20 μm, the size of the formed floc becomes unstable, and it becomes difficult to coagulate the polymer crosslinked product (I) with good reproducibility. In the present invention, neutral means pH
It refers to a range of 6 to 8, and a pH of less than 6 is called acidic.

The amount of the inorganic compound soluble in acidic water used in the present invention is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the polymer crosslinked product (I). 0.
If the addition is less than 01 parts by weight, the effect of the addition of the inorganic compound is unlikely to be exerted, and the aggregation becomes insufficient. In addition, when a large amount exceeding 10 parts by weight is added, aggregation of the particles during the aggregation treatment may progress too much, and it may be difficult to maintain the shape of the spherical fine particles.

In the coagulation treatment using an inorganic compound soluble in acidic water as described above, the bulk density of the aggregate of the polymerized crosslinked product (I) is 0.1 to 0.9 g / cm ³ , especially 0.1 g / cm ³ .
It is more preferable to set the aggregation state in the range of 2 to 0.7 g / cm ³ . The shape and size of the polymerized crosslinked product (I) are not limited, but in consideration of the next step of separation, drying and crushing of particles, particles of 20 to 10000 μm, more preferably 30 to 1000 μm are formed. It is better to let. If the size is less than 20 μm, large energy or special equipment is required for separating the particles,
If it exceeds 00 μm, large energy is required for crushing. The solid-liquid separation of the aggregate of the polymerized crosslinked product (I) and the suspension after the aggregation treatment is performed by coagulating the polymerized crosslinked product (I) in the suspension into particles of an appropriate size as described above. Therefore, it can be easily performed by using various general solid-liquid separation devices such as suction filtration, pressure filtration, and centrifugal filtration.

Crosslinked polymer (I) separated from the suspension
Is passed through a drying step and then to a crushing step in which the aggregate of the polymerized crosslinked product (I) is crushed to an average particle diameter of the polymerized crosslinked product (I) before substantial aggregation. In the pulverization, a pulverizer conventionally used for industrially producing powders or particles can be used without limitation. Since the aggregate of the polymerized crosslinked product (I) produced in the present invention has only a point junction or a slight surface junction at its interface, it can be easily produced by a pulverizer having a relatively simple mechanism with a small amount of energy. To the average particle size of the polymerized crosslinked product (I) before aggregation.

The particles of the polymerized crosslinked product (I) after crushing are mixed with the polymerized crosslinked product (I) in a suspension obtained by aqueous suspension polymerization.
Is substantially retained, and is suitably used in the next sulfonation step.

In the present invention, the suspending agent which can be used in the aqueous suspension polymerization can be appropriately selected from conventionally known ones, and may be a surfactant having a molecular weight of 2,000 or less and / or
Alternatively, inorganic fine particles that are hardly soluble in neutral water and soluble in acidic water are preferable. By using these surfactants and / or inorganic fine particles, the aqueous suspension polymerization of the monomer mixture (A) can be stably performed, and the polymer crosslinked product (I) suitable for the present invention is obtained. In addition, since these suspending agents are easily removed in the sulfonation step, the solid matter of the polymerized crosslinked product (I) taken out of the suspension polymerization system is dried without washing, and is then transferred to the next sulfonation step. Since it can be used, it is preferable from the viewpoint of simplifying the manufacturing process.

Examples of the surfactant which can be used as a suspending agent in the aqueous suspension polymerization in the present invention include known anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Etc. can be used. Among them, the use of an anionic surfactant is preferred from the viewpoint of the stability of the suspension polymerization system and the easiness of the aggregation treatment after the completion of the suspension polymerization.

Examples of the anionic surfactant which can be suitably used as a suspending agent include fatty acid salts such as sodium oleate and castor oil potassium, alkyl sulfate ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, dodecylbenzene sulfone Alkyl benzene sulfonate such as sodium acid, alkyl naphthalene sulfonate, alkane sulfonate, dialkyl sulfosuccinate, alkyl phosphate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl sulfate, etc. And one or more of these can be used.

Nonionic surfactants which can be suitably used as a suspending agent include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester And polyoxyethylene alkylamines and glycerin fatty acid esters. One or more of these can be used.

Examples of the cationic surfactant which can be suitably used as a suspending agent include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride. And one or more of these can be used.

Examples of the amphoteric surfactant which can be suitably used as a suspending agent include, for example, lauryl dimethylamine oxide. These surfactants are preferably used by appropriately adjusting the composition and the amount of the surfactant so that the average particle diameter of the obtained polymerized crosslinked product (I) is in the range of 1 to 50 μm.

The amount of the surfactant used is preferably in the range of 0.02 to 5 parts by weight based on 100 parts by weight of the monomer mixture (A). If the amount is less than 0.02 parts by weight, the suspension becomes unstable and a uniform dispersion cannot be obtained. If the amount exceeds 5 parts by weight, many fine particles having an average particle diameter of less than 1 μm are formed. It is difficult to obtain the crosslinked product (I) stably.

Examples of the inorganic fine particles which can be suitably used as the suspending agent of the present invention include phosphates such as calcium triphosphate and hydroxyapatite, aluminum hydroxide, calcium sulfate, barium carbonate, magnesium carbonate and calcium carbonate. Inorganic salts,
One or more of these can be used. Considering the ease of handling during suspension polymerization, the use of phosphate is particularly preferred.

The average particle size of the inorganic fine particles that can be used in the suspending agent is not particularly limited as long as it does not affect the handling properties. 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 a dispersed phase particle in an electrorheological fluid composition. . When the average particle diameter of the inorganic fine particles is less than 0.01 μm or more than 1 μm,
In some cases, the suspension system becomes unstable, and only an electrorheological fluid having insufficient shear stress and current characteristics may be obtained.

The inorganic fine particles used as a suspending agent are preferably used by appropriately adjusting the composition and amount thereof so that the average particle size of the obtained polymerized crosslinked product (I) is in the range of 1 to 50 μm. No.

The amount of the inorganic fine particles to be 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, and if it exceeds 20 parts by weight, a uniform dispersion cannot be obtained. In any case, the polymer crosslinked product (I) may not be obtained stably.

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 or polyallyl aliphatic compounds such as diallyl adipate, and one or more of these can be used. .

In the present invention, the monomer mixture (A) comprises a vinyl aromatic compound (a) and a 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.

In the suspension polymerization method of the present invention, for example, a dispersion medium and a suspending agent are charged, and a monomer mixture (A) having a polymerization initiator dissolved therein is added thereto with stirring, and a dispersion machine or a stirrer is used. After controlling the particle size, the polymerization can be carried out in a suspended state.

Examples of the polymerization initiator for suspension polymerization include benzoyl peroxide, tertiary butyl hydroxy peroxide, cumene peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, tertiary butyl perphthalate and 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 of the emulsion.

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 80 ° C. for about 2 to 30 hours, and particularly at 80 ° C. until the conversion reaches 30% by weight or more and less than 80% by weight. Polymerization at a temperature of 50 ° C. or more and less than 80 ° C. for about 0.3 to 10 hours until the polymerization rate reaches a temperature of less than 40% by weight and less than 70% by weight. At 80 ° C or higher until
It is preferable to carry out the polymerization for about 20 hours.

The polymer crosslinked product (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 suitably pulverizing or granulating as necessary. Is obtained.

As the sulfonating agent used for sulfonating the aromatic ring present in the polymerized crosslinked product (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, sulfonation is usually performed at a temperature in 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 in the absence of a solvent or in the presence of a solvent that does not swell with respect to the crosslinked polymer (I) or in the presence of a solvent that is swellable with respect to the crosslinked polymer (I). Can be.

The solvent which does not swell with respect to the crosslinked polymer (I) may be any solvent which does not swell the crosslinked polymer (I) and is inert to the sulfonating agent. And aliphatic hydrocarbons such as ligroin.

The solvent capable of swelling with respect to the crosslinked polymer (I) may be any solvent that swells the crosslinked polymer (I) and is inactive with respect to the sulfonating agent. For example, ethylene dichloride, trichloroethylene, Examples thereof include tetrachloroethane, nitrobenzene, propylene chloride, and carbon tetrachloride.

The use amount of these solvents is preferably within a range of 1000 parts by weight or less based on 100 parts by weight of the polymer crosslinked product (I).

In the sulfonation reaction, 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 a large amount of water is used to remove the acid and the like remaining in the particles. It is good to wash thoroughly. 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.

The water in the dispersed phase particles in the present invention 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, and examples thereof include silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane; liquid paraffin, decane, dodecane, methylnaphthalene, and 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, bromodiphenyl Halogenated hydrocarbons such as phenylmethane, chlorodecane, dichlorodecane, trichlorodecane, bromodecane, chlorododecane, dichlorododecane, and bromododecane; halogenated diphenylether compounds such as chlorodiphenylether, dichlorodiphenylether, trichlorodiphenylether, and bromodiphenylether; 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. The ratio of the dispersed phase particles to the electrically insulating dispersion medium in the composition is as follows:
It is preferable that the amount be in the range of 50 to 500 parts by weight with respect to 100 parts by weight of the former. 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. When the amount of the dispersion medium is less than 50 parts by weight,
The fluidity of the prepared composition itself may be reduced, making it difficult to use it 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, the viscosity of the electrorheological fluid composition, or the shear stress. Various additives such as agents can be added to the composition.

[0060]

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.

[0061]

Example 1 A 20-liter reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 12 liters of water, and 15 g of sodium dodecylbenzenesulfonate was dispersed.
Further, a mixture consisting of 2.6 kg of styrene, 0.4 kg of industrial divinylbenzene (a mixture of 55 wt% of divinylbenzene, 35 wt% of ethylstyrene, etc., manufactured by Wako Pure Chemical Industries, Ltd.) and 100 g of benzoyl peroxide was added. Thereafter, the contents in the reactor were dispersed at a stirring speed of 12000 rpm using an Ebara Milder V type (a homogenizer manufactured by Ebara Corporation) to control the particle size. Then 7
After polymerization at 5 ° C for 1 hour, the polymerization temperature was further raised to 95 ° C and heated for 4 hours to obtain a suspension of a polymerized crosslinked product. This suspension was cooled to 70 ° C., kept at 70 ° C., added with 40 g of a 25% by weight aqueous solution of polyaluminum chloride, and further heated at 70 ° C. for 10 minutes. A floc-like substance formed by aggregation was formed. Then, when this suspension was filtered using a suction filter, the filterability was good and the water content was about 10% by weight.
Filtration was possible in 30 minutes. 80 ° C using hot air dryer
For 3 hours to obtain 2.96 kg of a block-shaped polymer crosslinked product having a bulk density of 0.25 g / cm ³ (hereinafter referred to as a polymer crosslinked product (1)).

A 2 liter glass-lined reaction vessel 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. 800 g of 25% by weight fuming sulfuric acid 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 perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water and 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 was dried at 80 ° C. for 10 hours using a vacuum dryer to obtain 119 g of dispersed phase particles composed of a spherical sulfonated polymer (hereinafter referred to as dispersed phase particles (1)).

The average particle size of the obtained dispersed phase particles (1) was measured by using a particle size distribution analyzer (SALD-1 manufactured by Shimadzu Corporation).
000) was 2.5 μm. When the ion exchange capacity of the dispersed phase particles (1) was quantified by a neutralization titration method and an elemental analysis method, 5.7 mg equivalent / g in the neutralization titration method and 5.6 mg equivalent / g in the elemental analysis method.
g. The water content in the dispersed phase particles (1) was measured using a Karl Fischer moisture meter (MPS-3, manufactured by Kyoto Electronics Industry Co., Ltd.).
As a result of measurement using P), 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) was used as Shin-Etsu Silicone Oil KF96-20CS ( 70 g of dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) to obtain an electrorheological fluid composition of the present invention (hereinafter referred to as a fluid composition (1)).

[0064]

Example 2 12 liters of water was charged into a 20 liter reactor equipped with a stirrer, reflux condenser and thermometer, 0.4 kg of calcium triphosphate was dispersed, and 0.9 g of sodium dodecylbenzenesulfonate was dissolved. Thereafter, a mixture consisting of 2.84 kg of styrene, 0.16 kg of the same industrial-use divinylbenzene used in Example 1 and 50 g of azobisisobutyronitrile was added. afterwards,
The content in the reactor was dispersed at a stirring speed of 9000 rpm using an Ebara Milder V-type to control the particle size. Then, after polymerization at 65 ° C for 2 hours, the polymerization temperature was further increased to 90 ° C.
C. and heated for 6 hours to obtain a suspension of a crosslinked polymer. While the suspension was cooled to 70 ° C. and kept at 70 ° C., a dispersion liquid in which 60 g of magnesium carbonate (particle diameter: 2 μm) was dispersed in 600 g of methanol was added in advance, and the mixture was further heated at 70 ° C. for 10 minutes. However, flocs formed by agglomeration of particles in the suspension were formed. Then, when this suspension was filtered using a suction filter, the filterability was good, the water content was about 10% by weight, and the filtration was completed in 25 minutes. Further, 8
After drying at 0 ° C. for 3 hours, a block-shaped polymer crosslinked product having a bulk density of 0.21 g / cm ³ (hereinafter referred to as a polymer crosslinked product (2))
$ 2.98 kg was obtained.

A 20 liter glass-lined reactor equipped with a stirrer, thermometer and dropping funnel was charged with 50 g of the crosslinked polymer (2), and 800 g of 98% by weight concentrated sulfuric acid was added to obtain a uniform dispersion. Next, the mixture was heated and stirred at 80 ° C. for 24 hours to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water and acetone. The obtained solid was neutralized with 280 ml of a 10% by weight aqueous sodium hydroxide solution, and then sufficiently washed with water.
Next, it was dried at 80 ° C. for 10 hours using a vacuum dryer to obtain 98 g of dispersed phase particles composed of spherical sulfonated polymer (hereinafter referred to as dispersed phase particles (2)).

When the average particle size of the obtained dispersed phase particles (2) was measured using a particle size distribution analyzer, it was 4 μm. When the ion exchange capacity of the dispersed phase particles (2) was quantified by a neutralization titration method and an elemental analysis method, it was 4.6 mg equivalent / g by the neutralization titration method and 4.5 mg equivalent / g by the elemental analysis method. 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 referred to as a fluid composition (2)}.

[0068]

COMPARATIVE EXAMPLE 1 A 20-liter reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 12 liters of water, and 15 g of sodium dodecylbenzenesulfonate was dispersed.
Further, a mixture consisting of 2.6 kg of styrene, 0.4 kg of industrial divinylbenzene used in Example 1 and 100 g of benzoyl peroxide was added. Thereafter, the contents in the reactor were dispersed at a stirring speed of 12000 rpm using an Ebara Milder V-type to control the particle size. Then 7
After polymerization at 5 ° C for 1 hour, the polymerization temperature was further raised to 95 ° C and heated for 4 hours to obtain a suspension of a polymerized crosslinked product. When the suspension was filtered using a suction filter, the filterability deteriorated with the lapse of time, and the filtration was not completed even after 6 hours, and the filtration was impossible.

[0069]

Comparative Example 2 12 liters of water was charged into a 20 liter reactor equipped with a stirrer, a reflux condenser and a thermometer, 0.4 kg of calcium triphosphate was dispersed, and 0.9 g of sodium dodecylbenzenesulfonate was dissolved. Thereafter, a mixture of 2.84 kg of styrene, 0.16 kg of the same industrial divinylbenzene as used in Example 1 and 50 g of azobisisobutyronitrile was added. afterwards,
The content in the reactor was dispersed at a stirring speed of 9000 rpm using an Ebara Milder V-type to control the particle size. Then, after polymerization at 65 ° C for 2 hours, the polymerization temperature was further increased to 90 ° C.
C. and heated for 6 hours to obtain a suspension of a crosslinked polymer. A suspension in which 15 g of powdery silica (AEROSIL (registered trademark, manufactured by Nippon Aerosil Co., Ltd., particle size: 0.016 μm)) was previously dispersed in 150 ml of methanol while cooling the suspension to 70 ° C. and maintaining the temperature at 70 ° C. Was added and further heated for 10 minutes to maintain 70 ° C.,
In the suspension, flocs formed by agglomeration of particles were formed. Then, when this suspension was filtered using a suction filter, the filterability was good, the water content was about 12% by weight, and filtration was possible in 35 minutes. Further, 8
It was dried at 0 ° C. for 3 hours to obtain 3.24 kg of a block polymer crosslinked product having a bulk density of 0.28 g / cm ³ (hereinafter referred to as comparative polymer crosslinked product (1)).

In a 2-liter four-neck separable flask equipped with a stirrer, a thermometer and a dropping funnel, 50 g of the comparative polymer crosslinked product (1) was charged, and 800 g of 98% by weight concentrated sulfuric acid was added 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 perform a sulfonation reaction. Thereafter, the reaction mixture was poured into water at 0 ° C., filtered, and washed with water and acetone. 280 ml of a 10% by weight aqueous sodium hydroxide solution was obtained.
And then washed thoroughly with water. Next, it was dried at 80 ° C. for 10 hours using a vacuum drier to obtain 110 g of comparative dispersed phase particles composed of a spherical sulfonated polymer (hereinafter referred to as comparative dispersed phase particles (1)).

When the average particle size of the obtained comparative dispersed phase particles (1) was measured using a particle size distribution analyzer, it was 4 μm.
Met. When the ion exchange capacity of the comparative dispersed phase particles (1) was quantified by neutralization titration and elemental analysis, 4.6 mg equivalent / g by neutralization titration and 4.6 by elemental analysis.
mg equivalent / g. The water content in the comparative dispersed phase particles (1) was measured using a Karl Fischer moisture meter, and was 2.4 parts by weight.

30 g of the obtained comparative dispersed phase particles (1) 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. A product (hereinafter referred to as a comparative fluid composition (1)) was obtained.

[0073]

Example 5 Each of the fluid compositions (1), (2) and the comparative fluid composition (1) obtained in Examples 1 and 2 and Comparative Example 2 were placed in a rotary viscometer with a coaxial electric field. / Outer cylinder gap
AC external electric field 4,000 V / mm (frequency: 60 Hz) under the conditions of 0 mm, shear rate 400 s ~ ¹ and temperature 25 ° C
The shear stress value (initial value) and the current density (initial value) flowing at that time were measured.

Further, the shear stress value (value after 14 days) and the current density (value after 14 days) after continuous operation of the viscometer at 25 ° C. for 14 days with an external electric field of 4,000 V / mm applied. ) Was measured to determine the stability over time of the fluid composition.

The results are shown in Table 1.

[0076]

[Table 1]

The electrorheological fluid has a higher shear stress value obtained when a relatively weak electric field is applied, and has a better current characteristic that the current density flowing at that time is smaller. 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 fluid obtained from the shear stress value and the current density observed when an electric field of 4000 V / mm was applied to each of the fluid compositions (1) and (2) and the comparative fluid composition (1) Table 1 shows the initial value and the value after 14 days of the Z value of the composition.

As is clear from Table 1, the fluid compositions (1) and (2) 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) and (2) of the present invention have a Z value of 2.6 or more at the initial stage, and have a Z value of 14 days.
The value did not decrease, and it was found that the composition was an electrorheological fluid composition having excellent stability over time in the balance between shear stress characteristics and current characteristics.

On the other hand, the comparative fluid composition (1) had an initial Z value of 0.7, which was smaller than the fluid composition of the present invention, and was inferior in the balance between shear stress characteristics and current characteristics. In addition, the temporal stability of the shear stress and the current density was inferior to the fluid composition of the present invention.

[0081]

The electrorheological fluid composition obtained by the method of the present invention has a long-term stability 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. Because it is very excellent, it can be effectively used for torque transmission actuators such as clutches and brakes, control actuators such as engine mounts, dampers, valves, and electrorheological fluid ink jets.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C10N 30:00 40:04 40:08 40:14 60:10 70:00 (72) Inventor Minoru Kobayashi 1-chome 25 Kannondai, Tsukuba City, Ibaraki Prefecture Address 12 Nippon Shokubai Co., Ltd. Tsukuba Research Laboratories (56) References JP-A-3-215597 (JP, A) JP-A-5-112608 (JP, A) JP-A-5-112790 (JP, A) JP-A Sho 59-8711 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10M 143/10 B01J 13/00 C10M 151/02 F16D 35/00 C10N 20:06 C10N 40:04 C10N 40 : 08 C10N 40:14 C10N 60:10 C10N 70:00

Claims (3)

(57) [Claims] 1. A monomer mixture (A) containing a vinyl aromatic compound (a) and a polyvinyl compound (b) as essential components and, if necessary, other vinyl compounds (c), is subjected to aqueous suspension polymerization to carry out polymerization crosslinking. body was synthesized (I), then the polymer crosslinked (I) a composition obtained by dispersing the dispersed phase particles consisting of an aromatic ring sulfonated polymer obtained by sulfonating present in the electrically insulating dispersion medium in a in things, the suspension of the polymer crosslinked product obtained by aqueous suspension polymerization (I), after adding an inorganic compound soluble in acidic water, thereby aggregating the polymer crosslinked body (I), wherein method of manufacturing an electro-rheological fluid composition characterized by combining said polymer crosslinked with (I) by from suspension to separate the polymer crosslinked body (I). 2. The method for producing an electrorheological fluid composition according to claim 1, wherein the inorganic compound soluble in acidic water is inorganic fine particles which are hardly soluble in neutral water. 3. A suspending agent used for aqueous suspension polymerization of the monomer mixture (A) is a surfactant having a molecular weight of 2,000 or less and / or inorganic fine particles which are hardly soluble in neutral water and soluble in acidic water. A method for producing the electrorheological fluid composition according to claim 1.