JPH0873882A - Homogenous electroviscous fluid - Google Patents

Abstract

PURPOSE: To obtain the subject fluid, comprising a compound containing a nonrigid atomic group, having aggregating properties and bound thereto without causing any problems in settling and aggregation, excellent in stability with time, usable within a wide temperature range at a lower cost than that of a liquid crystalline substance and useful for transmission, etc., of a torque. CONSTITUTION: This fluid comprises a compound containing a nonrigid atomic group, having aggregating properties and bound to both terminals of a flexible molecular chain. Furthermore, e.g. a recurring unit containing an atomic group having an aromatic hydrocarbon and/or a short-chain aliphatic hydrocarbon as a main constituent element and containing a hydrogen bonding group such as amide bond, urethane bond or urea bond or a polar group such as ester bond, carbonate bond or ether bond as a basic unit, specifically a recurring structure of formula I or II (P and R are each a short-chain alkylene or an aromatic hydrocarbon) having 2-50 polymerization degree, etc., is preferably used as the atomic group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a uniform electrorheological fluid, and is used as an actuator for positioning control, vibration absorption, torque transmission, artificial muscle, and the like.

[0002]

2. Description of the Related Art An electrorheological fluid whose viscosity changes remarkably instantaneously and reversibly when a voltage is applied is well known as a so-called Winslow fluid in which water-containing fine particles such as silica and starch have been dispersed in insulating oil since the 1940s. . After that, many improvements have been proposed, such as a method of using ion-exchange resin particles or zeolite particles as the water-containing fine particles and a method of using non-water-containing particles such as organic semiconductor particles and surface-insulated conductive particles. However, the method using these particles shows excellent performance in the short term, but in the long term, sedimentation and separation of particles and agglomeration of precipitated particles into coagulated clay are unavoidable, which is a major obstacle to practical use.

On the other hand, a liquid crystalline substance has been attracting attention as a homogeneous electrorheological fluid which does not cause the problems of particle sedimentation and aggregation. The liquid crystal substance undergoes molecular orientation when a voltage is applied and its viscosity increases. In particular, in a liquid crystalline substance in which two or more liquid crystalline groups are bound to one molecular chain, the domains formed by the liquid crystalline groups are bound by flexible molecular chains, and therefore the increase in viscosity due to voltage application is remarkable ( JP-A-5-32988). However, the liquid crystal substance has a problem in practical use such that the operating temperature is limited to a relatively high temperature and the cost is high.

[0004]

The present invention has no problem of sedimentation and aggregation, is excellent in electrical stability and stability over time, can be used in a wide temperature range, and has a lower temperature than liquid crystalline substances. It is intended to provide an electrorheological fluid that can be obtained at a cost.

[0005]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to solve the above-mentioned drawbacks of electrorheological fluids, as a result of the compound having cohesive atomic groups at both ends, the viscosity of the compound is changed to an electric field. It was found that the temperature range in which the electrorheological effect is exhibited can be expanded by making the atomic group having the cohesive property non-rigid, and the present invention has been reached. That is, the present invention is an electrorheological fluid composed of a compound in which a non-rigid and cohesive atomic group is bonded to both ends of a flexible molecular chain.

The term "non-rigid" in the present invention refers to an atomic group which does not include a linear rod-shaped structure in its molecular structure. Here, the rod-like structure means that two or more aromatic hydrocarbons, cyclohexane, dioxane, and pyrimidine are each bonded in series directly or through an ester bond, an imide bond, or the like, so that they can freely rotate. A structure with few parts. Rigidity is not preferable because the temperature at which the electrorheological effect is exhibited becomes high and the range becomes narrow.

As a concrete example of the atomic group which is not rigid,
1) Aromatic hydrocarbons and / or short-chain aliphatic hydrocarbons as main constituents, amide bond, urethane bond,
A repeating structure having an atomic group containing a hydrogen-bonding group such as a urea bond and a polar group such as an ester bond, a carbonate bond and an ether bond as a basic unit (specific examples are Chemical Formulas 1 to 4) 2) Aliphatic Examples thereof include a repeating structure having a basic unit of an atomic group having a hydrocarbon as a main chain and an aromatic hydrocarbon as a side chain (a specific example is Chemical Formula 5). These atomic groups form domains due to the cohesive force of aromatic rings and aliphatic chains, the cohesive force between hydrogen bonding groups and polar groups, and exhibit responsiveness to an electric field. Its degree of polymerization is 1 to 1
00 is preferable and 2 to 50 is more preferable. Further, as long as the object of the present invention is not impaired, the types of atomic groups having non-rigidity and aggregating property which are bonded to both ends of the flexible molecular chain may be the same or different.

[0008]

Embedded image

[0009]

Embedded image

[0010]

[Chemical 3]

[0011]

[Chemical 4]

[0012]

[Chemical 5]

However, in the repeating basic unit, as described above, two or more aromatic hydrocarbons, cyclohexane, dioxane, and pyrimidine are bonded in series directly or via an ester bond, an imide bond, or the like. In that case, rigidity is generated, the temperature at which the electrorheological effect is exhibited becomes high, and the range thereof is narrowed, which is not preferable, and it does not apply to the "non-rigid and cohesive atomic group" in the present invention. For example, a Schiff base type (chemical formula 6), a benzoic acid ester type (chemical formula 7), a biphenyl type (chemical formula 8), a cyclohexylcarboxylic acid ester (chemical formula 9), a phenylcyclohexane type (chemical formula 10), a pyrimidine type (chemical formula 11), Dioxane (Chemical formula 1
2), cyclohexylcyclohexane type (chemical formula 13)
The liquid crystalline group such as is a rigid atomic group.

[0014]

[Chemical 6]

In the present invention, the flexible molecular chain is a molecular chain which is soft and has fluidity even at a relatively low temperature, and which does not prevent aggregation of non-rigid atomic groups added to both ends when a voltage is applied. . When an oligomer or polymer is synthesized with units forming a flexible molecular chain, its glass transition temperature (Tg) is 25 ° C or lower, preferably 0 ° C or lower, and more preferably -20 ° C or lower. Further, specifically, for example, it is a molecular chain mainly composed of a homopolymer or copolymer of the units shown in 1) to 5) below.

[0016] 1) ethylene, propylene, -CH ₂ CR ¹ R ^2, such as isobutylene - (wherein R ^1, R ² represents a hydrogen or a methyl, ethyl and alkyl groups of 1 to 10 carbon atoms, R ^1, R ² may be the same or different). 2)-(CR ¹ R ² ) = such as butadiene and isoprene
(CR ³ R ⁴⁾ - (wherein ^{R 1, R 2, R 3} , R 4 is
An olefinic hydrocarbon represented by hydrogen or an alkyl group having 1 to 10 carbon atoms such as methyl and ethyl, and R ¹ , R ² , R ³ and R ⁴ may be the same or different.

3) Oxyalkylene represented by --O (CR ¹ R ² ) _m- (wherein R ¹ and R ² are the same as above, m = 1-5) such as oxymethylene and oxyethylene. 4) -S (CR ¹ R such as thiomethylene and thioethylene
² ) A _{thioalkylene represented by m-} (wherein R ¹ , R ² and m are the same as defined above). 5) —SiR ³ R ⁴ O— such as dimethylsiloxane (wherein R ³ and R ⁴ represent hydrogen or an alkyl group having 1 to 10 carbon atoms such as methyl and ethyl, and R ³ and R ⁴ may be the same or different) Also good) siloxane.

The degree of polymerization of this flexible molecular chain is preferably 1 to 50, more preferably 2 to 20. From the viewpoint of electrical stability, the electric resistance is preferably 10 ⁸ Ωcm or more. As a method of synthesizing the compound used in the present invention, a method of synthesizing a flexible molecular chain and an atomic group having nonrigidity and cohesiveness in advance, and then linking them to construct a target structure, After the synthesis of the flexible molecular chain, the raw material of the non-rigid and cohesive atomic group may be added, and both ends may be grown.

The compound of the present invention can be modified and used within a range not impairing the object of the present invention. For example, introduction of a polar functional group as a terminal or a side chain of the compound is a preferable means from the viewpoint of improving the responsiveness of the molecule to an electric field. Further, adding a diluent or a plasticizer to the compound is also one of the preferable means in that the viscosity of the compound itself can be lowered and the change in viscosity upon application of an electric field can be enhanced. In that case, a diluent having a structure similar to a flexible molecular chain is particularly preferable.

[0020]

EXAMPLES The present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples. The electrorheological effect was measured according to the following method. [Measurement method of electrorheological effect] A pair of parallel disks modified so that the entire plate-opposing surface forms an electrode (the lower disk is connected to a motor for rotation, the upper disk is connected to a torque meter and shear stress is applied). The electro-viscous effect was measured using a parallel plate-type rotary viscometer having the (1). The shear stress generated when a sample is sandwiched between electrodes and sheared at a specified temperature and a specified shear rate is measured when voltage is applied between the electrodes and when voltage is not applied. And That is, the generated shear stress in this example is defined as follows.

(Generated shear stress) = (Shear stress when voltage is applied)-(Shear stress when no voltage is applied) The measurement conditions in this example are: counter electrode diameter 32 m.
m, distance between electrodes 0.50 mm, average shear rate 10 se
c ⁻¹ , applied voltage DC ¹ kV.

[0022]

Example 1 10 ml of hexane solution of butyl lithium
(1.6 mol / l) was diluted 10 times with purified tetrahydrofuran (THF), and 320 ml (1.0 mol / l) of a THF solution of styrene monomer was atomized therein to carry out a polystyrene polymerization reaction at 0 ° C. It was After stirring for 30 minutes, 2.0 g of allyl bromide was added to stop the polymerization reaction. This was reprecipitated and purified with methanol to give polystyrene having an average degree of polymerization of 20 (allyl at one end) of about 30 g.
Obtained.

20.0 g of the polystyrene having a double bond at one end and 5.1 g of polysiloxane having a SiH group at both ends (degree of polymerization: 15) obtained above were dissolved in 100 ml of THF to form chloroplatinic acid hexahydrate. Add 10 mg and 24 at 60 ℃
Allowed to react for hours. After completion of the reaction, THF was distilled off to obtain about 15 g of compound A having nonrigid and cohesive atomic groups bonded to both ends of the flexible molecular chain.

[0024]

[Chemical 7]

The generated shear stress of this compound A was measured and found to be +34 Pa at 30 ° C. and +4 at 0 ° C.
It was 8 Pa, and the electrorheological effect was exhibited even at a low temperature.

[0026]

Example 2 Benzoic acid 10.0 g, dicyclohexylcarbodiimide 21.0 g, triethylamine 12.0 g
A solution of 6.3 g of allyl alcohol / 30 ml of dichloromethane was added dropwise to 150 ml of a dichloromethane solution in which was dissolved to carry out an esterification reaction. After stirring for 24 hours at room temperature, the precipitated dicyclohexylurea was removed by filtration. The filtrate was washed twice with 10% hydrochloric acid, dichloromethane was distilled off, and recrystallization was performed with ethanol to obtain about 10 g of a white solid.

5 g of the white solid obtained above and S at both ends
4.4 g of a siloxane polymer having an iH group (degree of polymerization: 4) was dissolved in 100 ml of THF, and 10 mg of hexachloroplatinic acid hexahydrate was dissolved.
Was added and reacted at 60 ° C. for 24 hours. After the reaction, T
HF was distilled off to obtain about 9 g of Compound B (Chemical Formula 15) in which a non-rigid and cohesive atomic group was bonded to both ends of the flexible molecular chain.

The generated shear stress of this compound B was measured to be +29 Pa at 30 ° C. and +4 at 0 ° C.
It was 1 Pa, and the electrorheological effect was exhibited even at a low temperature.

[0029]

Embedded image

[0030]

Comparative Example 1 37 g of p-hydroxybenzoic acid was dissolved in a mixed solution of 30 g of potassium hydroxide, 40 ml of water and 190 ml of ethanol, and then 0.3 g of potassium iodide was added,
40 g of 5-bromopentene was added dropwise. After refluxing this at 80 ° C. for 12 hours, water 40 kept at pH 3.0 with hydrochloric acid was added.
The resulting precipitate was dissolved in ethanol at 70 ° C. and recrystallized to obtain about 40 g of product C.

To 14 g of the product C, 16 g of thionyl chloride and a few drops of dimethylformamide were added, and after stirring at room temperature for 30 minutes, excess thionyl chloride was distilled off under vacuum. This was dissolved in 110 ml of THF, and then 8 g of p-cyanophenol and 9 g of triethylamine were dissolved in THF at 5 ° C.
It was dropped into 280 ml and stirred at 5 ° C. for 4 hours. After that, THF was distilled off under reduced pressure, and new dichloromethane 300 was added.
It was dissolved in ml and washed 3 times with a separating funnel. After dehydration with sodium sulfate, the product was purified by passing through a column packed with silica gel. After distilling off dichloromethane, the product was recrystallized using ethanol at 70 ° C. to obtain a product D (about 20 g).

This product D13.3 g and SiH at both ends
6.1 g of siloxane polymer having a group (degree of polymerization 4)
It was dissolved in 100 ml of F, 10 mg of hexachloroplatinic acid hexahydrate was added, and the mixture was reacted at 60 ° C. for 24 hours. After completion of the reaction, THF
Was distilled off to obtain a compound E (chemical formula 16) having a liquid crystalline group at both ends of the flexible molecular chain. When the generated shear stress of this compound E was measured, it was +47 Pa, 0 at 30 ° C.
It solidified and could not be measured at ° C.

[0033]

[Chemical 9]

[0034]

By the constitution of the present invention, sedimentation,
It is possible to provide an electrorheological fluid that is free from aggregation problems, has excellent stability over time, can be used in a wide temperature range, and can be obtained at a lower cost than liquid crystalline substances.

Claims (1)

[Claims] 1. An electrorheological fluid comprising a compound in which a non-rigid and cohesive atomic group is bonded to both ends of a flexible molecular chain.