JPH0967586A - Electroviscous fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a homogeneous electroviscous fluid which is stable against the repetition of application of a voltage or the application of a voltage for a long period of time and can be utilized in an actuator for absorption of vibration or mechanical control. SOLUTION: This electroviscous fluid comprises a diluent (I) with a liq. crystalline group bonded to a flexible molecular chain with a percentage bond of 25 to 80%; a compd. (II) with a liq. crystalline group bonded to a flexible molecular chain with a percentage bond of 5 to 20%; and a diluent (III) not having any crystalline group comprising a flexible molecular chain. Based on 100 pts.wt. in total wt. of the compd. (I) and the compd. (II), the amt. of the compd. (I) is 50 to 80 pts.wt., the amt. of the compd. (II) is 50 to 20 pts.wt., and the amt. of the diluent (III) is 10 to 200 pts.wt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel electrorheological fluid, which is a homogeneous electrorheological fluid that exhibits a large electrorheological effect in a stable manner for a long period of time.
Used for actuators such as torque transmission, dampers, and mechanical positioning control.

[0002]

2. Description of the Related Art Winslow is an electrorheological fluid.
For about half a century since the invention of, a large number of so-called dispersion fluids have been proposed in which water-containing particles or dielectric particles such as conductive particles or semiconductor particles whose surface is coated with an insulating thin film are dispersed in insulating oil. . However, these fluids have a poor dispersion stability of particles and have an essential problem of particle sedimentation, and have not been put into practical use.

On the other hand, a lot of studies have been conducted on polar liquids, liquid crystals, polymer solutions and the like for homogeneous electrorheological fluids which do not use particles, but their electrorheological effects have been extremely small and neglected. Recently, as the difficulty of a dispersed electrorheological fluid has become clear, the possibility of a homogeneous fluid has been revisited, and reports and patents on a homogeneous electrorheological fluid without particles have begun to be published. In particular, in a fluid using a thermotropic liquid crystalline compound in which a plurality of liquid crystalline groups are bonded in a chain (Japanese Patent Laid-Open No. 5-32988), a large electrorheological effect superior to the conventional dispersion system is obtained.

[0004]

The electrorheological fluid using the above-mentioned thermotropic liquid crystal can obtain a large increase in viscosity, but since it has a high viscosity, it is usually diluted with a low viscosity compound such as polysiloxane before use. For this reason,
There is a tendency that the diluent and the liquid crystal are separated from each other under repeated voltage application or long-term voltage application conditions.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to solve the problems of the above-mentioned electrorheological fluid composed of thermotropic liquid crystal, and found that the compound is bonded to a compound having a low liquid crystal group bonding rate. The inventors have found that mixing a compound having a high ratio improves the compatibility with a compound composed of a flexible molecular chain used as a diluent, and arrived at the present invention. That is, the present invention is as follows. 1. Diluent (I) having a liquid crystal group bonded to a flexible molecular chain at a binding rate of 25% to 80%, and a binding rate of 5 to the flexible molecular chain.
% To 20% of compound (II) having a liquid crystal group bonded
And a diluent (III) having no liquid crystal group consisting of a flexible molecular chain, which comprises compound (I) and compound (I
50 to 80 parts by weight of compound (I) and 50 to 2 parts of compound (II) based on 100 parts by weight of the total of I).
An electrorheological fluid comprising 0 parts by weight and 10 to 200 parts by weight of the diluent (III). 2. The electrorheological fluid according to the above 1, wherein the flexible molecular chain is a siloxane polymer.

Next, the present invention will be described in detail. The term "flexible molecular chain" as used in the present invention means 1) siloxane represented by -SiR1 R2 O- (wherein R1 and R2 represent an alkyl group or a phenyl group) such as dimethylsiloxane and phenylmethylsiloxane, and 2) methylene. , Ethylene, propylene, etc. --Cm H2m-- (where m is 1 to 2
Indicates an integer of 0. ) Alkylene 3) Oxyethylene, oxypropylene, oxybutylene, etc. -O
Cm H2m- (where m is an integer of 1 to 5) is a monomer or homopolymer or copolymer having 1 unit of oxyalkylene or the like, and its degree of polymerization is 2
To 100, more preferably 2 to 50. The shape of the polymer may be linear, branched or star-shaped. These molecular chains are, in the unit shown in 1) above, instead of some or all of R1 and R2,
In the units shown in 2) and 3), instead of some H,
It may be substituted with an alkyl group having a chain length of 20 or less, a fluoroalkyl group, a phenyl group, an oligosiloxane, a cyano group, or a substituent formed by combining them. In addition, the above molecular chain may be
O-, -COO-, -CO-, -CONH-, -OCO
It is also possible to interpose O-, -S-, -SO-, -SO2-, phenylene group and the like.

The liquid crystalline group referred to in the present invention means a Schiff base type, benzoic acid ester type, azo type, dioxane type, azoxy type, tetrazine type, biphenyl type, terphenyl type, cyclohexene type, cyclohexyl type, cyclohexylcarboxylic acid. System, cyclohexylcyclohexane ester system, cyclohexylethane system, phenylcyclohexane system, biphenylcyclohexane system, cholesteryl system, pyrimidine system, tolan system, fluorophenylene system,
Bicyclooctane-based, Cuban-based, cyanothiophenyl ester-based, ferroelectric liquid crystal and other commonly known low-molecular liquid crystals (eg, Shoichi Matsumoto, Yoshida Tsunoda "Basics and Applications of Liquid Crystals", Industrial Survey , P.107-162, etc.) and a group containing a liquid crystallinity expressing structure (generally called mesogen). Further, a hydrogen bond type liquid crystal exhibiting liquid crystallinity by forming a molecular complex pair of a plurality of molecules by hydrogen bond, an ionic liquid crystal in which a quaternized nitrogen atom or a metal atom is introduced into the molecule, a crown ether to the above mesogen. Ion-dipole interaction type liquid crystal, etc. introduced with metal salt and compounded by Takashi Kato, production research,
46, No. 6 (1994.6, p16-22) is also included in the liquid crystalline group in the present invention.

The compounds (I) and (II) of the present invention contain the above-mentioned liquid crystal groups, and depending on the contained form, they are (a) a main chain type compound, (b) a side chain type compound, and (c) a terminal. The compound of type can be classified into a complex compound in which a plurality of structures of (d), (a) to (c) are present in the compound. First, in (a) the main chain type compound, the liquid crystal group is bonded to the flexible molecular chain unit of the above 1) to 3) directly or via a bonding group to form the main chain of the polymer. As the bonding group used here, -O-, -COO-, -CO-,-
CONH-, -OCOO-, -S-, -SO-, -SO
2- and the like groups can be mentioned.

Next, the (b) side chain type compound and the (c) terminal type compound will be described. In (b), the liquid crystal group is bonded as a side chain in the flexible molecular chain, and (c).
In (1), it is bonded to the end of the main chain and / or the branched chain of the flexible molecular chain as an end group. In this case, the liquid crystalline group has a part of R1 or R2 in the flexible molecular chain unit having the structure shown in 1), and H in the flexible molecular chain unit having the structure shown in 2) to 3). Are partially bonded to the polymer either directly or through substitution groups. The linking group used here is -Cp.
H2p- (where p is an integer of 1 to 20), -C
p H2p-qFq − (where p is an integer from 1 to 20 and q is 1
Indicates an integer in the range of ≤q≤2p. ),-(CH2 CH2
O) n-, -Si (CH3) 2-, -O-, -COO
Representative examples include groups such as —, —CO—, and —CONH— and chains obtained by combining these groups.

The bond ratio of the liquid crystalline group in the present invention refers to the ratio of the number of introduced liquid crystalline groups to the total number of repeating units of the flexible molecular chain, and is represented by the following formula. (% Binding) = 100 × (number of introduced liquid crystalline groups) /
(Total number of repeating units of flexible molecular chain) The liquid crystal group bonding ratio of the compound (I) in the composition of the present invention is 2
It is necessary to be 5% or more and 80% or less, and 25%
It is preferably 50% or more and 50% or less. When the bonding rate of the liquid crystal group is less than 25%, the electrorheological effect is small, which is not preferable. When it exceeds 80%, the diluent (II
Separation from I) is likely to occur, which is not preferable.

The liquid crystal group bonding rate of the compound (II) in the composition of the present invention must be 5 to 20%.
It is preferably 0 to 20% from the viewpoint of stability when a voltage is applied. When the liquid crystal group bonding rate is less than 5% or higher than 20%, the diluent (III) is likely to be separated when a voltage is applied, which is not preferable. Diluent in the composition of the invention (II
I) is a compound consisting of the above flexible molecular chain,
The liquid crystal group is not bonded. Typical examples thereof include silicone oil, phenyl-modified silicone oil, olefin (co) polymer and the like.

Next, the content of each composition is defined based on 100 parts by weight of the total of the compound (I) and the compound (II). The content of the compound (I) is 50 to 80 parts by weight in terms of the electrorheological effect and the stability when a voltage is applied.
60 to 80 parts by weight is preferable. When the content of the compound (I) is less than 50 parts by weight, the electrorheological effect is small, and
If it exceeds 80 parts by weight, the compound (I) (I
Separation of I) and diluent (III) is likely to occur. Similarly, the content of the compound (II) is 50 to 20 parts by weight, preferably 40 to 20 parts by weight.

The content of the diluent (III) is 10 to 200 parts by weight, preferably 20 to 90 parts by weight, from the viewpoints of viscosity when no voltage is applied, electrorheological effect and stability after voltage application. When the content of the diluent (III) is less than 10 parts by weight, the viscosity of the composition is high when no voltage is applied and only a small electrorheological effect is obtained. On the other hand, when the amount exceeds 200 parts by weight, the shear stress generated when a voltage is applied becomes small, and the compound (I) and (II) are separated after the voltage is applied.

The flexible molecular chain species of the compounds (I), (II) and (III) may be the same or different from each other, but from the viewpoint of compatibility, the same is more preferable. The liquid crystal group species of the compounds (I) and (II) do not have to be the same as each other, and more than one kind of liquid crystal group may be bonded to the compound (I) or (II).

The compounds (I), (II) and (III) are
Two or three types may be simultaneously synthesized by adjusting the charged amount of raw materials, reaction conditions, prepolymer composition, etc., or they may be independently synthesized and then mixed. As a method of mixing a plurality of kinds of polymers, a) a solvent mixing method of dissolving the polymers in a common solvent and then evaporating the solvents to form a blend, b) heating the polymers to reduce the viscosity, and then stirring Well-known are the heat-mixing method of mixing, the mechanical mixing method of mixing using c) a roll, a kneader, etc. In the present invention, the compounds (I), (II),
The mixing method of (III) may be any of a) b) c) and is not particularly limited.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be specifically described and supplemented by Examples. The measurement of the electrorheological effect, which is a basic characteristic of the electrorheological fluid, was performed according to the following method. <Measurement method of electrorheological effect> A pair of parallel disks modified so that the entire plate facing surface forms an electrode (the lower disk is connected to a motor to rotate, the upper disk is connected to a torque meter and shear stress is applied. The electro-viscous effect was measured by using a parallel plate type rotational viscometer having a measurement of The sample was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and the sample was sheared at a shear rate of 200 sec -1 at 40 ° C. and a DC voltage of 0 and 2 kV / mm.
The shear stress and the current value when the voltage was applied were measured. The generated shear stress referred to in the present invention is an increment of the shear stress due to the application of a voltage.

[0017]

Example 1 (1) Synthesis of Liquid Crystal Group 1) Synthesis of Tosyl Form 16 g of ethylene glycol monoallyl ether was dissolved in 120 ml of acetonitrile together with 24 g of tosyl chloride and 18 g of triethylamine and stirred at room temperature for 18 hours. After confirming the completion of the reaction by TLC,
The solution was poured into water and the product was extracted with ethyl acetate. After drying and concentration, the obtained crude product was purified by silica gel column chromatography to obtain 30 g of compound A shown in the following chemical formula 1.

[0018]

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2) Synthesis of Carboxylic Acid Form 18 g of p-hydroxybenzoic acid dissolved in 80 ml of ethanol was mixed with an aqueous solution of potassium hydroxide (a solution of 18 g of potassium hydroxide dissolved in 24 ml of water). 30 g of the obtained compound A was added dropwise. This solution was heated and stirred at 80 ° C. for 2.5 hours, allowed to cool, and 160 ml of water
When concentrated hydrochloric acid was added to adjust the pH to 1, a white solid was precipitated. After the white solid is isolated by filtration, washed with water and dried,
Recrystallization was performed to obtain 12.5 g of compound B shown in the following chemical formula 2.

[0020]

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3) Esterification reaction 10 g of the compound B obtained in 2) was added to thionyl chloride 2
5 g was added, and the mixture was stirred at room temperature for 30 minutes to remove an excess of thionyl chloride in vacuo as an acid chloride. An acid chloride dissolved in 50 ml of tetrahydrofuran (THF) was added to 6 g of p-cyanophenol and 6 g of triethylamine.
Was added dropwise to 50 ml of THF dissolved therein, and the mixture was further stirred at 0 ° C. for 1 hour. The THF was removed under vacuum and the residue was dissolved in dichloromethane and washed with water. Purification by silica gel column chromatography gave 13 g of compound C shown in the following chemical formula 3.

[0022]

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(2) Synthesis of Polymer 1) Synthesis of Compound Having Liquid Crystalline Group Bonded to Polysiloxane Chain at 31% Bonding Rate m = 2 in (Prepolymer Structure) shown in Chemical Formula 4 below.
Dimethylsiloxane having an average composition of 0 and n = 11.
3 g of methylhydrogensiloxane random copolymer,
Compound C (5.2 g) was dissolved in tetrahydrofuran (50 ml), a small amount of chloroplatinic acid catalyst was added, and the mixture was reacted at 60 ° C. for 5 hours. By infrared absorption spectrum and high performance liquid chromatography analysis, it was confirmed that about 20% of the compound C was converted into an inactive substance, and the remaining about 80% was reacted with the siloxane copolymer. Subsequently, 2 g of 1-pentene was added to completely crush unreacted Si-H groups, and then 500 ml of methanol was used to precipitate and collect the polymer D. When the structure of this polymer D was analyzed by NMR, the liquid crystal binding rate was 31%.

[0024]

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2) Synthesis of a compound in which a liquid crystalline group is bonded to a polysiloxane chain with a bonding ratio of 15% In the above-mentioned chemical formula 4 (prepolymer structure), m = 2
9, dimethylsiloxane / methylhydrogensiloxane random copolymer 3 having an average composition of n = 16.3
g and compound C 2.6 g were reacted in the same manner as in (2) 1) to obtain polymer E. The structure of this polymer E is NMR
When analyzed by, the liquid crystal binding rate was 15%. (3) Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Polymer D, polymer E, and polydimethylsiloxane (Shin-Etsu Silicone KF96-20cSt: hereinafter referred to as DMS) are 100 parts by weight in total of polymer D and polymer E. On the basis of polymer D67 parts by weight, polymer E33
Parts by weight and DMS 50 parts by weight, and mixed to obtain 120
An electrorheological fluid F was obtained by heating and stirring at ℃. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid F was measured according to (Method for measuring electrorheological effect), a generated shear stress of 2000 Pa was observed. 3) Stability under an electric field An electrorheological fluid F was sandwiched between electrodes with a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours, but separation occurred. Was not observed.

[0026]

Comparative Example 1 Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Polymer D and DMS (Shin-Etsu Silicone: KF96-20)
cSt) was mixed at a weight ratio of 100 parts by weight of polymer D and 50 parts by weight of DMS based on 100 parts by weight of polymer D, and heated and stirred at 120 ° C. to obtain electrorheological fluid G. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid G was measured according to (Method for measuring electrorheological effect), a generated shear stress of 6000 Pa was observed. 3) Stability under an electric field An electrorheological fluid G was sandwiched between electrodes with a facing electrode diameter of 32 mm and an electrode spacing of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. Part dimethyl polysiloxane separated.

[0027]

Comparative Example 2 Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Based on 100 parts by weight of the total weight of Polymer D, Polymer E and DMS, the total weight of Polymer D and Polymer E is Polymer D.
67 parts by weight, 33 parts by weight of polymer E and 5 parts by weight of DMS were mixed and heated and stirred at 120 ° C. to obtain an electrorheological fluid H. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid H was measured according to (Method for measuring electrorheological effect), only a small electrorheological effect of 100 Pa was obtained. 3) Stability under an electric field An electrorheological fluid H was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. ,
No separation of polymer E, DMS was observed.

[0028]

Comparative Example 3 Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Based on the total weight of Polymer D, Polymer E and DMS being 100 parts by weight of Polymer D, Polymer D
50 parts by weight, 50 parts by weight of polymer E, and 400 parts by weight of DMS were mixed in a weight ratio, and heated and stirred at 120 ° C. to obtain an electrorheological fluid I. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid I was measured according to (Method for measuring electrorheological effect), a small shear stress of 200 Pa was observed. 3) Stability under an electric field An electrorheological fluid I was sandwiched between electrodes with a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. Partially separated.

[0029]

Example 2 Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Polymer D, polymer E, and polydimethylsiloxane (Shin-Etsu Silicone KF96-20cSt: hereinafter referred to as DMS) were added to polymer D and polymer E in a total weight of 100. Based on parts by weight, Polymer D 75 parts by weight, Polymer E25
Parts by weight and DMS 50 parts by weight, and mixed to obtain 120
An electrorheological fluid J was obtained by heating and stirring at ° C. 2) Electrorheological Effect When the electrorheological effect of the electrorheological fluid J was measured according to (Measurement method of electrorheological effect), a generated shear stress of 3000 Pa was observed. 3) Stability under an electric field An electrorheological fluid J was sandwiched between electrodes with a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours, but separated. Was not observed.

[0030]

Example 3 Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Based on 100 parts by weight of the total weight of Polymer D, Polymer E and DMS, the total weight of Polymer D and Polymer E is Polymer D.
67 parts by weight, 33 parts by weight of polymer E and 30 parts by weight of DMS were mixed, and heated and stirred at 120 ° C. to obtain an electrorheological fluid L. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid L was measured according to (Method for measuring electrorheological effect), a generated shear stress of 2500 Pa was observed. 3) Stability under an electric field An electrorheological fluid L was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. No separation of D, polymer E, DMS was observed.

[0031]

Example 4 Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Based on 100 parts by weight of the total weight of Polymer D, Polymer E and DMS, the total weight of Polymer D and Polymer E is Polymer D.
67 parts by weight, polymer E 33 parts by weight, and DMS 80 parts by weight were mixed, and heated and stirred at 120 ° C. to obtain an electrorheological fluid M. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid M was measured according to (Measuring method of electrorheological effect), a generated shear stress of 1300 Pa was observed. 3) Stability under an electric field An electrorheological fluid M was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode spacing of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. No separation of D, polymer E, DMS was observed.

[0032]

Fifth Embodiment (1) Dimethylsiloxane methylhydrogen having an average composition of m = 22 and n = 4 in the synthesis of a compound (prepolymer structure) in which a liquid crystalline group is bonded to a polysiloxane chain at a bonding rate of 11% 15 g of siloxane random copolymer, 9.6 g of compound C
Was reacted in the same procedure as in Example 1 (2) 1) to give polymer N
I got When the structure of this polymer N was analyzed by NMR, the liquid crystal binding rate was 11%. (2) Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Based on the total weight of Polymer D, Polymer N and DMS being 100 parts by weight of Polymer D, Polymer D
67 parts by weight, polymer N 33 parts by weight and DMS 50 parts by weight were mixed, and heated and stirred at 120 ° C. to obtain an electrorheological fluid O. 2) Electrorheological Effect When the electrorheological effect of the electrorheological fluid O was measured according to (Measuring Method of Electrorheological Effect), a generated shear stress of 500 Pa was observed. 3) Stability under an electric field An electrorheological fluid O was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. No separation of D, polymer N, DMS was observed.

[0033]

Example 6 (1) Synthesis of Polymer 1) Synthesis of Compound Having Polysiloxane Chain Bonded with Liquid Crystalline Group at 30% Bonding Ratio (Prepolymer Structure) Dimethyl having an average composition of m = 31 and n = 17 Siloxane / methylhydrogen siloxane random copolymer 3 g, compound C 5.5 g
Was reacted according to Example 1 (2) 1) to precipitate and collect the polymer P. When the structure of this polymer P was analyzed by NMR, the liquid crystal binding rate was 30%. (2) Preparation and evaluation of electrorheological fluid 1) Preparation of electrorheological fluid Polymer P, polymer E, and DMS are polymer P based on the total weight of polymer P and polymer E of 100 parts by weight.
67 parts by weight, 33 parts by weight of polymer E and 50 parts by weight of DMS were mixed and heated and stirred at 120 ° C. to obtain an electrorheological fluid Q. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid Q was measured according to (Measuring method of electrorheological effect), a generated shear stress of 2300 Pa was observed. 3) Stability under an electric field An electrorheological fluid Q was sandwiched between electrodes with a facing electrode diameter of 32 mm and an electrode spacing of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. No separation of P, polymer E and DMS was observed.

[0034]

Example 7 (1) Synthesis of Liquid Crystal Group 1) Synthesis of Carboxylic Acid Form 20 g of p-hydroxybenzoic acid, 0.2 g of potassium iodide
g, an aqueous potassium hydroxide solution (20 g of potassium hydroxide + 24 ml of water), and 100 ml of ethanol were mixed, 17.2 g of allyl bromide was added, and the mixture was heated and stirred at 80 ° C. for 12 hours. After allowing to cool, the reaction mixture was poured into water and adjusted to pH 3 to produce a white precipitate. The precipitate is filtered off and purified by silica gel column chromatography to give 18 g of compound R shown in the chemical formula 5 below.
Obtained.

[0035]

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2) Esterification reaction 9 g of compound R obtained in 1), 30 thionyl chloride
g, p-cyanophenol 6.4 g and triethylamine 7 g were subjected to an esterification reaction according to the procedure of Example 1 (1) 3) to obtain 14 g of compound S shown in the following Chemical formula 6.

[0037]

[Chemical 6]

(2) Synthesis of Polymer 1) Synthesis of a compound in which a liquid crystalline group is bonded to a polysiloxane chain at a bond ratio of 40% (prepolymer structure) dimethylsiloxane having an average composition of m = 13 and n = 15. Methyl hydrogen siloxane random copolymer 3 g, compound S 4.7 g
Was dissolved in 50 ml of tetrahydrofuran, a small amount of chloroplatinic acid catalyst was added, and the mixture was reacted at 60 ° C. for 5 hours. The progress of the reaction was confirmed by analysis by infrared absorption spectrum and high performance liquid chromatography. Subsequently, 3 g of 1-pentene was added to completely crush the unreacted Si-H groups, and then the solvent and the pentene remaining in the system were distilled off to recover the polymer T. 2) Synthesis of a compound in which a liquid crystalline group is bonded to a polysiloxane chain at a bonding rate of 15% (prepolymer structure), m = 29, n = 16.3
3 g of dimethylsiloxane-methylhydrogensiloxane random copolymer having the following average composition, compound S1.
8 g was reacted in the same procedure as in (2) 1) to obtain a polymer U.

(3) Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Polymer T, polymer U, and DMS are polymer T based on a total weight of 100 parts by weight of polymer T and polymer U.
67 parts by weight, polymer U 33 parts by weight, and DMS 50 parts by weight were mixed, and heated and stirred at 120 ° C. to obtain an electrorheological fluid V. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid V was measured according to (Method for measuring electrorheological effect), a generated shear stress of 3300 Pa was observed. 3) Stability under an electric field An electrorheological fluid V was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. No separation of T, polymer U, DMS was observed.

[0040]

Example 8 (1) Synthesis of Liquid Crystal Group Example 1 (1) was prepared using 9 g of the compound R obtained in Example 7 (1) 1), 30 g of thionyl chloride, 6.6 g of p-methoxyphenol and 7 g of triethylamine. )
The esterification reaction is carried out according to the procedure of 3), and 14 g of the following compound 7
The compound W shown in was obtained.

[0041]

[Chemical 7]

(2) Synthesis of Polymer 1) Synthesis of a compound in which a liquid crystalline group is bonded to a polysiloxane chain at a bond rate of 40% (prepolymer structure) dimethylsiloxane having an average composition of m = 13 and n = 15. Methyl hydrogen siloxane random copolymer 3 g, compound W 4.8 g
Was used to carry out a reaction according to the procedure of Example 7 (2) 1) to obtain a polymer X. 2) Synthesis of a compound in which a liquid crystalline group is bonded to a polysiloxane chain at a bonding rate of 15% (prepolymer structure), m = 29, n = 16.3
3 g of dimethylsiloxane-methylhydrogensiloxane random copolymer having the following average composition, compound W1.
8 g was reacted according to the procedure of Example 7 (2) 1) to obtain a polymer Y.

(3) Preparation and Evaluation of Electrorheological Fluid 1) Preparation of Electrorheological Fluid Polymer X, polymer Y and DMS were added to polymer X based on the total weight of polymer X and polymer Y of 100 parts by weight.
67 parts by weight, 33 parts by weight of the polymer Y and 50 parts by weight of DMS were mixed and heated and stirred at 120 ° C. to obtain an electrorheological fluid Z. 2) Electrorheological effect When the electrorheological effect of the electrorheological fluid Z was measured according to (Method for measuring electrorheological effect), a generated shear stress of 1300 Pa was observed. 3) Stability under an electric field An electrorheological fluid Z was sandwiched between electrodes set to have a facing electrode diameter of 32 mm and an electrode interval of 0.50 mm, and a DC voltage of 2 kV / mm was applied at 40 ° C. for 10 hours. No separation of X, polymer Y, DMS was observed. The above Examples and Comparative Examples are summarized and shown in Tables 1, 2 and 3 below. In the table, (1), (2) and (3) represent the compound (1), the compound (2) and the diluent (3), respectively, and the structures of the compounds (1) and (2) are shown below. Indicated by.

[0044]

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The structure of the diluent (3) is shown in Chemical formula 9 below.

[0046]

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[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

INDUSTRIAL APPLICABILITY The present invention provides an electrorheological fluid having excellent stability in which a compound having a liquid crystalline group bonded thereto and a diluent do not separate even when a voltage is applied for a long time or a voltage is repeatedly applied. The electrorheological fluid of the present invention includes a valve, a clutch,
It can be stably used for a long period of time in new compact and electronically controlled actuators such as brakes and torque converters. This is especially useful for developing high-precision machine control system systems.

Claims (2)

[Claims] 1. A binding rate of 25% or more and 80% to a flexible molecular chain.
A liquid crystal group-bonded diluent (I), a compound (II) having a liquid crystal group bonded to the flexible molecular chain at a binding rate of 5% or more and 20% or less, and a liquid crystal group composed of the flexible molecular chain 50 to 80 parts by weight of the compound (I) and 50 to 50 parts by weight of the compound (II) based on 100 parts by weight of the total weight of the compound (I) and the compound (II).
An electrorheological fluid comprising 20 parts by weight and 10 to 200 parts by weight of the diluent (III). 2. The electrorheological fluid according to claim 1, wherein the flexible molecular chain is a siloxane polymer.