JP2505842B2 - Electrorheological fluid composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrorheological fluid composition. More specifically, the present invention relates to an electrorheological fluid composition that generates a large shear stress by applying an electric field change and is excellent in stability of the generated shear stress with time.

(Prior Art) An electrorheological fluid is, for example, a fluid obtained by dispersing and suspending solid particles in an insulating dispersion medium, and its rheological or flow property is a viscoplastic type due to an electric field change. It is known as a fluid that exhibits a so-called Winslow effect in which the viscosity significantly increases when an external electric field is applied and a large shear stress is induced when an external electric field is applied. Since the Winslow effect has a characteristic of quick response, the electrorheological fluid has been attempted to be applied to a clutch, a damper, a brake, a shock absorber, an actuator and the like.

Conventionally, as an electrorheological fluid, solid particles such as cellulose, starch, soybean casein, polystyrene-based ion exchange resin, and polyacrylate crosslinked body are dispersed in insulating oil such as silicone oil, diphenyl chloride, trans oil, etc. Things are known. However, these electrorheological fluids have problems that the induced shear stress is small and their stability with time is poor.

(Problems to be Solved by the Invention) The present invention solves the above problems.

Therefore, an object of the present invention is to provide an electrorheological fluid composition that generates a large shear stress by applying an electric field change, and has stability over time that it is maintained over a long period of time. To provide.

(Means and Actions for Solving the Problems) (However, R ¹ , R ³ and R ⁴ are each independently hydrogen or a linear or branched alkyl group having 1 to 4 carbon atoms,
R ² represents a linear or branched alkylene group having 1 to 4 carbon atoms, and X represents —NH— or —O—. ) Amino group-containing unsaturated monomer and / or salt thereof (I) of 20 to 100% by weight and other polymerizable monomer (II) of 0 to 80% by weight are polymerized. The present invention relates to an electrorheological fluid composition obtained by dispersing the polymer obtained and / or a crosslinked product thereof in an insulating dispersion medium.

The amino group-containing unsaturated monomer used in the present invention is represented by the above general formula, for example, 2-aminoethyl (meth) acrylate and 2-aminoethyl (meth).
Acrylamide, 2- [methylamino] ethyl (meth)
Acrylate, 2- [ethylamino] ethyl (meth) acrylate, 2- [N, N-dimethylamino] ethyl (meth) acrylate, 2- [N, N-dimethylamino] ethyl (meth) acrylamide, 2- [N , N-diethylamino] ethyl (meth) acrylate, 2- [N, N-diethylamino] ethyl (meth) acrylamide, 3- [N, N
-Diethylamino] propyl (meth) acrylate, 3
-[N, N-diethylamino] propyl (meth) acrylamide, 3- [N, N-dipropylamino] propyl (meth) acrylate, 3- [N, N-dipropylamino] propyl (meth) acrylamide, 3- [N, N-dimethylamino] propyl (meth) acrylate, 3- [N, N-
Dimethyl] propyl (meth) acrylamide, 3- [N,
N-dimethylamino] butyl (meth) acrylate, 3
-[N, N-dimethylamino) butyl (meth) acrylamide and the like can be mentioned, and one or more of these can be used.

Examples of the salt of the amino group-containing unsaturated monomer used in the present invention include hydrochloride, sulfate, bromate, and iodate of the amino group-containing unsaturated monomer represented by the above general formula.
Fluorate, nitrate, cyanate, thiocyanate, phosphate, borate, carbonate, sulfite, hypochlorite,
Inorganic acid salts such as perchlorates; Acetates of amino group-containing unsaturated monomers, organic carboxylic acid salts such as formates, propionates, benzoates, etc. of amino group-containing unsaturated monomers Organic sulfonic acid salts such as p-toluenesulfonate, benzenesulfonate, methanesulfonate, ethanesulfonate, isethionate and dodecylbenzenesulfonate;
2-[(meth) acryloyl obtained by reacting an amino group-containing unsaturated monomer represented by the above general formula with a quaternizing agent such as methyl halide, ethyl halide, phenyl halide and dimethyl sulfate. Oxy] ethyltrimethylammonium chloride, 2-[(meth) acryloyloxy] ethyltrimethylammonium bromide, 2-[(meth) acryloyloxy] ethyltrimethylammonium iodide, 2-[(meth) acryloyloxy] ethyldimethylfume Examples thereof include quaternary ammonium salts such as methyl sulfate of enylammonium chloride and 2-[(meth) acryloyloxy] ethyltrimethyl, and one or more of these can be used.

The monomer component, which is a raw material when obtaining the polymer used in the present invention, needs to contain 20% by weight or more of the amino group-containing unsaturated monomer and / or its salt (I). When the amount of the amino group-containing unsaturated monomer and / or its salt (I) used is less than 20% by weight in the monomer component, it is sufficient to change the electric field in the finally obtained electrorheological fluid composition. Shear stress cannot be obtained, and the stability over time becomes poor.

Other polymerizable monomers (II) that can be used in the present invention are not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2 -Acrylamide-2
-Methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, 3-sulfopropyl (meth) acrylate, 1-sulfopropan-2-yl (meth) acrylate, 2-sulfopropyl (meth) acrylate, 1
-Sulfobutan-2-yl (meth) acrylate, 2-
Unsaturated carboxylic acids and unsaturated sulfonic acids such as sulfobutyl (meth) acrylate, 3-sulfobutan-2-yl (meth) acrylate, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid and their alkali metals Dissociative group-containing unsaturated monomers such as salts, alkaline earth metal salts, other metal salts, ammonium salts, organic amine salts, pyridinium salts or guanidinium salts; (meth) acrylamide, (meth) acrylonitrile, vinyl acetate, etc. Water-soluble unsaturated monomer; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, Xy polyethylene glycol mono (meth) acrylate, methoxy polypropylene glycol mono (meth) acrylate, methoxy polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, ethoxy polypropylene glycol mono (meth) acrylate, ethoxy polybutylene glycol Mono (meth) acrylate, methoxypolyethylene glycol / polypropylene glycol mono (meth) acrylate, phenoxypolyethylene glycol mono (meth) acrylate, benzyloxypolyethylene glycol mono (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate (Meth) acrylic acid ester such as butyl (meth) acrylate; styrene, salt Vinyl, butadiene, isoprene, ethylene, etc. hydrophobic unsaturated monomers such as propylene may be mentioned, may be used alone or two or more thereof.

In the present invention, not only polymers obtained by polymerizing these monomer components, but also cross-linked products of these polymers can be effectively used. To obtain a cross-linked product of this polymer, for example, a cross-linking agent may be mixed in the monomer component in advance and then polymerized, or the polymer may be reacted with the cross-linking agent. Examples of these crosslinking agents include divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate. , Trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol di (meth) acrylate, N, N-methylenebisacrylamide, triallyl isocyanurate, trimethylolpropane diallyl ether, etc. Compounds having two or more unsaturated groups; ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, poly Glycerin, propylene glycol, diethanolamine, triethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, Sorubitsuto, sorbitan,
Polyhydric alcohols such as glucose, mannitol, mannitol, sucrose, glucose; ethylene glycol diglycidyl ether, glycerin diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether Examples thereof include polyepoxy compounds such as ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, and glycerin triglycidyl ether. One or more of them are used. be able to. When a polyhydric alcohol is used as a cross-linking agent, it is preferable to carry out heat treatment after polymerization at 150 ° C. to 250 ° C., and when using a polyepoxy compound at 50 ° C. to 250 ° C. The use of a cross-linking agent is preferable because it improves the stability over time of the resulting electrorheological fluid composition.

The polymerization method for obtaining the polymer and / or its cross-linked product used in the present invention may be any conventionally known method, for example, a method using a radical polymerization catalyst or irradiation with radiation, electron beams, ultraviolet rays or the like. There is a method. As the radical polymerization catalyst, peroxides such as hydrogen peroxide, benzoyl peroxide, quinene hydroperoxide, azo compounds such as azobisisobutyronitrile, and radicals such as persulfates such as ammonium persulfate and potassium persulfate Generator or these and sodium bisulfite,
A redox initiator is used in combination with a reducing agent such as L-ascorbic acid and ferrous salt. As the polymerization solvent, for example, water, methanol, ethanol, acetone, dimethylformamide, dimethylsulfoxide, hexane, cyclohexane, xylene, toluene, benzene, etc., or a mixture thereof can be used. The temperature at the time of polymerization varies depending on the type of catalyst used, but a relatively low temperature is preferable because the molecular weight of the polymer increases. But,
In order to complete the polymerization, the temperature is preferably in the range of 20 ° C or higher and 100 ° C or lower.

The concentration of the monomer in the polymerization system is not particularly limited, but it is preferably in the range of 20 to 80% by weight in view of easiness of control of the polymerization reaction, yield and economy. As the polymerization form, various forms can be adopted, for example, suspension polymerization, cast polymerization,
A method in which the gel-like hydropolymer is polymerized while being subdivided by the shearing force of a double-arm kneader (JP-A-57-34101). Among these, suspension polymerization, such as a method of suspending an aqueous monomer solution in a hydrophobic organic solvent and polymerizing, is particularly preferable in that spherical fine particles can be obtained.

The particle size and shape of the polymer and / or its crosslinked product used in the present invention are not particularly limited, but the particle size is preferably 0.1 to 500 μm. If the particle size is out of this range, the shear stress may not be sufficiently large when the obtained electrorheological fluid composition is electrically changed.

 The insulating dispersion medium used in the present invention is 10⁹Ωcm
If it is an electrically insulating liquid having the above electrical resistance,
Without limitation, for example, halogenated benzene, halogenated dif
Phenyl, halogenated diphenyl methane, halogenated diph
Phenyl ether, halogenated paraffin, halogenated sodium
Halogenated hydrocarbons such as phthalene; Daifloyl And de
Munam Low fluorinated compounds (made by Daikin Industries, Ltd.)
Polymer: Dioctyl phthalate, Trioctyl trimellitate
Chill, isodecyl trimellitate, dibutyl sebacate
Esters such as liquid paraffin, petroleum ether, petroleum
Benzene, xylene, benzene, toluene, tetraly
Hydrocarbons such as hydrogen and naphthalene; silicone oil, transformer oil
Etc. and mixtures thereof.

The ratio of the polymer and / or its crosslinked product to the insulating dispersion medium in the present invention is not particularly limited, but the insulating dispersion medium is not limited.
It is preferable that the amount of the polymer and / or its crosslinked product is 5 to 400 parts by weight based on 100 parts by weight. If the amount of the polymer and / or its cross-linked product is less than 5 parts by weight, the shear stress may not be sufficiently large when the electric field change is applied to the obtained electrorheological fluid composition, and if it exceeds 400 parts by weight. In some cases, the fluidity of the obtained composition itself is lowered and it becomes difficult to use it as an electrorheological fluid.

Although the reason why the electrorheological fluid composition of the present invention exhibits a remarkable Winslow effect is not clear, the electric field change is caused by the presence of a trace amount of water in the polymer and / or its crosslinked product in the composition. It is considered that a large shear stress is induced when applied. However, the water content in the polymer and / or its crosslinked product in the present invention is
20% by weight or less is preferable. If the water content exceeds 20% by weight, particles of the polymerized and / or crosslinked product thereof may adhere,
When a change in the electric field is applied, the current may become unstable and a large shear stress may not be obtained.

In the present invention, in order to improve the dispersibility of a polymer and / or a crosslinked product thereof in an insulating dispersion medium, adjust the viscosity of an electrorheological fluid composition, or improve shear stress, a surfactant and a polymer are added to the composition. Various additives such as a dispersant and a polymer thickener can be added.

(Effects of the Invention) The electrorheological fluid composition of the present invention provides a large shear stress when an external electric field is applied, and since the generated shear stress is excellent in stability over time, a clutch, a damper, a brake, a shock absorber, It can be effectively used for actuators, vibration transmitters, etc.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 Cyclohexane 1200 was placed in a two-necked four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a nitrogen gas introducing tube.
After charging and dissolving 12 g of sorbitan monostearate, the inside of the flask was replaced with nitrogen. On the other hand, 125 g (0.6 mol) of 2- (methacryloyl) oxyethyltrimethylammonium chloride, 37.6 g (0.4 mol) of sodium acrylate, 72 g (1.0 mol) of acrylic acid, and 18.5 g of N, N-methylenebisacrylamide 18.5 ( 0.12 mol) and 380 g of water were charged to prepare an aqueous monomer solution, and 0.4 g of ammonium persulfate was added and dissolved therein, and nitrogen gas was blown thereinto to remove oxygen existing in the aqueous solution. Then, the contents of the dropping funnel were added to and dispersed in the four-necked flask, and the temperature of the polymerization system was kept at 60 to 65 ° C. by a water bath while slightly introducing nitrogen gas, and the polymerization was continued for 3 hours. . Then, water in the system was distilled off by azeotropic distillation with cyclohexane, and the mixture was dried in excess to obtain a polymer (1). The average particle size of the polymer (1) was 81.2 μm (measured with a Shimadzu laser diffraction particle size distribution analyzer, the same applies hereinafter).

Example 2 In a cylindrical separable flask of 1, 184 g (1.0 mol) of 3- (N, N-diethylamino) propylacrylamide and trimethylolpropane triacrylate 0.0592
Then, g (0.002 mol) and 252 g of water were charged and stirred to dissolve uniformly. After purging with nitrogen, heat to 40 ° C in a hot water bath for 10
% Aqueous solution of ammonium persulfate and 1.0 g of 1% aqueous solution of L-ascorbic acid were added, and stirring was stopped to polymerize. After the initiation of polymerization, heat was generated, and after 30 minutes, the temperature rose to 82 ° C. After confirming that the temperature of the polymerization system has started to drop, put the water bath at 90 ° C.
And heated for an additional 1 hour. The hydrogel of the obtained polymer cross-linked product is subdivided, then dried, powdered and classified.
100 mesh standard sieve passing product (hereinafter referred to as polymer (2)
Say. ) Got.

Example 3 As an aqueous monomer solution, 71.5 g (0.5 mol) of 2- (N, N-dimethylamino) ethyl acrylate, 115 g (0.5 mol) of 2-acrylamido-2-methylpropanesulfonic acid,
N, N-methylenebisacrylamide 0.154g (0.001mol)
A polymer (3) having an average particle diameter of 96.4 μm was obtained in the same manner as in Example 1 except that and 318 g of water were used.

Example 4 144 g (0.8 mol) of 2-aminoethyl methacrylate hydrochloride as an aqueous monomer solution, 14.2 g (0.2 mol) of acrylamide
Mole), N, N-methylenebisacrylamide 0.31 g (0.00
2 mol) and 237 g of water were used in the same manner as in Example 2 to obtain a 100 mesh standard sieve passed product (hereinafter referred to as polymer (4)).

Comparative Example 1 Sodium acrylate 75.2 g (0.8
Mol), 144 g (2.0 mol) of acrylic acid, 18.5 g (0.12 mol) of N, N-methylenebisacrylamide and 357 g of water were used in the same manner as in Example 1 to obtain an average particle size of 85.2 μm.
To obtain a comparative polymer (1).

Comparative Example 2 Ane, which is a polystyrene-based strongly basic ion exchange resin
Bar light Dry IRA-400 (Organo Co., Ltd.)
Crushed and classified and passed through 100 mesh standard sieve (hereinafter, this
Is referred to as a comparative polymer (2). ) Got.

Examples 5 to 8 and Comparative Examples 3 to 4 20 g of each of the polymers shown in Table 1 was dried at 110 ° C. for 1 hour and then left in a room at a temperature of 20 ° C. and a relative humidity of 60% for 30 minutes to absorb moisture. After that, it was mixed and dispersed in 80 g of brombenzene. Each of the electrorheological fluid compositions thus obtained was placed in a coaxial double cylindrical rotational viscometer and the shear rate was adjusted to 40%.
Shear stress was measured when an external electric field of 2000 V / mm was applied at ⁰ sec ^-1 . Further, shear stress was measured after the viscometer was operated continuously for 3 days with an external electric field applied, and the temporal stability was examined.

 The results of measurement of shear stress are shown in Table 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page Examiner Koichi Nakano (56) References JP-A-60-209242 (JP, A) JP-A-61-259752 (JP, A)

Claims (1)

(57) [Claims] 1. A general formula (However, R ¹ , R ³ and R ⁴ are each independently hydrogen or a linear or branched alkyl group having 1 to 4 carbon atoms,
R ² represents a linear or branched alkylene group having 1 to 4 carbon atoms, and X represents —NH— or —O—. ) Amino group-containing unsaturated monomer and / or salt thereof (I) of 20 to 100% by weight and other polymerizable monomer (II) of 0 to 80% by weight are polymerized. An electrorheological fluid composition obtained by dispersing the obtained polymer and / or its crosslinked product in an insulating dispersion medium.