JPH0782585A - Electroviscous fluid - Google Patents

Abstract

PURPOSE:To obtain an electroviscous fluid which can be used in direct contact with a rubbery elastomer, esp. natural rubber, is excellent in dispersion stability, and exhibits stable thickening effects from low to very high temp. and a relatively low electric current. CONSTITUTION:An electroviscous fluid is obtd. by compounding a silicone oil contg. solid particles dispersed therein with a polyhydric alcohol and an aminomodified silicone in an amt. of 80-600 wt.% of the particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a clutch, a hydraulic valve, a shock absorber, a vibrator, an anti-vibration rubber, a variable damping damper, an engine mount, a bearing damper, a valve,
The present invention relates to an electrorheological fluid that can be used for electrical control of a display element or the like or that is used as a component in an electro-mechanical interface or the like for controlling a system for holding a work piece in a normal position.

[0002]

2. Description of the Related Art Electro-Rheological Fluid, Electro-Viscous Fluid whose viscosity changes with the application of voltage
scous Fluid,) has been known for a long time (Duff, AWP
hysical Review Vol, 4, No.1 (1896) 23). Initial research on electrorheological fluids focused on liquid-only systems, and the effect was inadequate, but after that, we moved to research on electrorheological fluids in solid dispersion systems, and obtained considerable electrorheological effects. Came to be.

As a mechanism for producing a thickening effect (ER effect) in an electrorheological fluid, for example, Klass shows that each particle, which is a dispersoid in the electrorheological fluid, has a two-layered dielectric polarization in the electric field. Double Laye
r), which is the main cause (Klass, D.
L., et al., J. of Applied Physics, Vol.38, No1 (196
7) 67). This is an electric double layer
The ion adsorbed around the dispersoid (silica gel, etc.) is evenly arranged on the outer surface of the dispersoid when E (electric field) = 0, but when E (electric field) = finite value Causes a bias in the ion distribution, and each particle exerts an electrostatic action on each other in the electric field. In this way, each particle forms a bridge (crosslink) between the electrodes, and shear resistance against stress, that is, an ER effect is developed.

Winslow also proposed an electrorheological fluid using paraffin and silica gel powder and water as a polarizing agent (Winslow, WM, J. of Applied Physics, Vol.
20 (1949) 1137). According to this Winslow study, the electrorheological effect of electrorheological fluid is called the Winslow effect.

Further, in many components using the electrorheological fluid, the electrorheological fluid is used in a state of being in direct contact with a material having rubber-like elasticity, but when a dispersion medium such as chlorinated paraffin is used. There is a problem that the rubber-like elastic material is deteriorated or decomposed by a stimulus such as heat or force to generate hydrogen chloride, and corrodes the metal part in the component using the electrorheological fluid.
In order to solve this problem, in JP-A-44998, silicone oil is used as a dispersion medium, and amino functionality, hydroxy functionality,
It has been proposed to use an acetoxy-functional polysiloxane as a dispersant to disperse silica gel containing 1 to 15% by weight of water to prepare an electrorheological fluid. However, in such an electrorheological fluid, the current value is large due to the presence of water, and the electrode is eluted by the action of electrolysis or evaporated at a high temperature, resulting in a decrease in the electrorheological effect. There is.

Therefore, it has recently been proposed to add a polyhydric alcohol as a polarizing agent in place of water so as to maintain the electrorheological effect. For example, JP-A 1-2845
Japanese Patent Laid-Open No. 95 discloses an electrorheological fluid in which silicone is used as a dispersion medium and silica gel is dispersed using amines as a dispersant together with a polyhydric alcohol.
It has been found that the use of amines has a high viscosity of the obtained electrorheological fluid, the use thereof is specified, and there is a problem in the electrorheological effect such as thickening ratio. Further, it has been found that the electroviscous effect decreases in high temperature use depending on the type of polyhydric alcohol.

[0007]

DISCLOSURE OF THE INVENTION The present invention is an electrorheological fluid that can be used in direct contact with a rubber-like elastic body, especially natural rubber, and has excellent dispersion stability and stable increase from low temperature to particularly high temperature. An object is to provide an electrorheological fluid that exhibits a viscous effect and a relatively small current value.

[0008]

The electrorheological fluid of the present invention is an electrorheological fluid in which solid particles are dispersed in silicone oil, and a polyhydric alcohol is blended, and an amino-modified silicone is added to the solid particles. It is characterized in that it is blended in a ratio of 80% by weight to 600% by weight.

First, as the solid particles in the present invention, silica gel, hydrous resin, diatomaceous earth, alumina, silica-alumina, zeolite, ion exchange resin, cellulose and the like can be used. These solid particles usually have a particle size of 5
It is possible to use one having a thickness of nm to 200 μm.

A particularly preferred solid particle in the present invention is silica gel, the particle size of which is 5 nm to 50 μm, preferably 5 nm to 10 μm, and the specific surface area measured by the BET method is generally 100 to 700 m ³ / g. Good to do.

In the electrorheological fluid of the present invention, the solid particles are 0.1% to 50% by weight, preferably 5% to 4% by weight.
The content is preferably 0% by weight, and if it exceeds 50% by weight, the electrorheological effect is deteriorated, which is not preferable.

Next, as the silicone oil, straight silicone oils such as polydimethylsiloxane, polymethylphenylsiloxane, polymethylhydrogensiloxane, polydiphenylsiloxane, and polymethyl long-chain alkylsiloxane, and polyether-modified siloxane,
Examples thereof include non-reactive modified siloxanes such as methylstyryl modified siloxane, alkyl modified siloxane, higher fatty acid ester modified siloxane, higher alkoxy modified siloxane, higher fatty acid modified siloxane, and fluorine modified siloxane. Further, at least one selected from these copolymers or a mixture thereof can be mentioned, and the viscosity at 25 ° C. is 1 cSt to 500 cSt, preferably 1 cSt to 100 cSt.

Next, the polyhydric alcohol is used as a polarization accelerator, and examples thereof include polyhydric alcohols and partial derivatives thereof. Examples of the polyhydric alcohol include dihydric alcohols and trihydric alcohols such as ethylene glycol, glycerin, propanediol, butanediol, pentanediol, hexanediol, and ethylene oxide units.
Polyethylene glycol having the general formula R [(O
C ₃ H ₆ ) _m OH] _n (wherein R represents hydrogen or a polyhydric alcohol residue, m represents an integer of 1 to 17 and n represents an integer of 1 to 6), and the general formula R-CH ( OH) (CH ₂ ) _n O
Examples thereof include those represented by H (in the formula, R represents hydrogen or a CH ₃ (CH ₂ ) _m − group, and m + n represents an integer of 2 to 14). Among these, polyhydric alcohols having a high boiling point are preferable, and for example, triethylene glycol, tetraethylene glycol, pentaethylene glycol are preferable.

The partial derivative of polyhydric alcohol is a partial derivative of polyhydric alcohol having at least one hydroxyl group, and some of the terminal hydroxyl groups of the above polyhydric alcohol are methyl group, ethyl group and propyl group. , Butyl groups, alkyl-substituted phenyl groups (alkyl groups substituted with phenyl groups have 1 to 25 carbon atoms), and other partial ethers, and some of the terminal hydroxyl groups are acetic acid, propionic acid, butyric acid Partial esters which have been esterified by the above are mentioned.

These polyhydric alcohols or their partial derivatives are usually used in a proportion of 1% by weight to 100% by weight, preferably 2% by weight to 80% by weight, based on silica gel. If the addition amount is less than 1% by weight, the ER effect is small, and if it exceeds 100% by weight, an electric current easily flows, which is not preferable.

Further, an acid, salt or base component may be further added. Such acid components include sulfuric acid, hydrochloric acid, nitric acid,
Inorganic acids such as perchloric acid, chromic acid, phosphoric acid, boric acid, or acetic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid,
Organic acids such as oxalic acid and malonic acid are used. The salt is a compound consisting of a metal or basic group (NH ₄ ⁺ , N ₂ H ₅ ^+, etc.) and an acid group, and any of these can be used. Among them, those which dissolve in a system of a polyhydric alcohol or a polyhydric alcohol partial derivative to dissociate, for example, those which form typical ionic crystals such as halides of alkali metals or alkaline earth metals, or alkali metal salts of organic acids. Are preferred. As a salt of this kind, LiC
1, NaCl, KCl, MgCl ₂ , CaCl ₂ , Ba
Cl ₂ , LiBr, NaBr, KBr, MgBr ₂ , L
_{iI, NaI, KI, AgNO 3} , Ca (NO 3) 2, N
aNO ₂ , NH ₄ NO ₃ , K ₂ SO ₄ , Na ₂ SO ₄ ,
There are NaHSO ₄ , (NH ₄ ) ₂ SO _4, or alkali metal salts of formic acid, acetic acid, oxalic acid, succinic acid and the like. The base is, for example, a hydroxide of an alkali metal or an alkaline earth metal, a carbonate of an alkali metal, an amine and the like, and a base which is dissolved in a polyhydric alcohol or a polyhydric alcohol partial derivative to dissociate is preferable. As this kind of base, N
aOH, KOH, Ca (OH) ₂ , Na ₂ CO ₃ , Na
Examples include HCO ₃ , K ₃ PO ₄ , Na ₃ PO ₄ , aniline, alkylamines and ethanolamines. Incidentally, the above-mentioned salt and base may be used in combination.

Acids, salts and bases can increase the polarization effect, but when used in combination with a polyhydric alcohol and / or a polyhydric alcohol partial derivative, the polarization effect can be further enhanced. It is possible, and it is advisable to use the electrorheological fluid in a proportion of 0.01% by weight to 5% by weight. ER when less than 0.01% by weight
If the effect is small, and if the amount exceeds 5% by weight, it becomes easier to energize and power consumption increases, which is not preferable.

Next, the amino-modified silicone which is a dispersant will be described. The amino-modified silicone used in the present invention is classified into the following four types due to its structure. (1) A polysiloxane having an amino group-containing substituent (Z) on its side chain,

[0019]

[Chemical 1]

(2) A polysiloxane having an amino group-containing substituent (Z) at both ends,

[0021]

[Chemical 2]

(3) Polysiloxane having an amino group-containing substituent (Z) at one end,

[0023]

[Chemical 3]

(4) A polysiloxane having an amino group-containing substituent (Z) on both the side chain and both ends,

[0025]

[Chemical 4]

Z in each of the above formulas (1) to (4) is -CH ₂ CH ₂ NH ₂ group or -CH ₂ CH ₂ group.
NHCH ₂ CH ₂ NH ₂ group, and the like.

The viscosity of such amino-modified silicone is 3 cSt to 4000 cSt at 25 ° C., preferably 50 cSt to 2000 cSt, and more preferably 2 cSt.
It is 50 cSt-1400 cSt. When the viscosity is low, the dispersibility of silica gel cannot be improved, resulting in high viscosity, the use thereof is specified, and the electrorheological effect such as the thickening ratio becomes low.

The amino-modified silicone is contained in the silica gel in an amount of 80% by weight to 600% by weight, preferably 10% by weight.
It is advisable to add 0% by weight to 570% by weight, and if it is less than 80% by weight, the dispersibility of silica gel cannot be improved and the viscosity becomes high, and its application is specified. On the other hand, if it is more than 600% by weight, the electrorheological effect such as the thickening ratio becomes low.

If desired, an ashless dispersant may be added to the electrorheological fluid of the present invention. When the ashless dispersant is added, the base viscosity of the electrorheological fluid can be lowered, and the application range of the mechanical system using the electrorheological fluid can be expanded. As the ashless dispersant, for example, sulfonates, phenates, phosphonates, succinimides, amines, nonionic dispersants and the like are used, and specifically, magnesium sulfonate, calcium sulfonate, calcium phosphonate, polybutenyl. Examples thereof include succinimide, sorbitan monooleate and sorbitan sesquioleate. Among them, polybutenyl succinimide is preferable. These are usually used in a proportion of 0.1 to 20% by weight based on the total electrorheological fluid.

In the electrorheological fluid of the present invention,
The dispersoid is in a very good dispersed state, but by adding a surfactant, the dispersibility can be made more excellent. As the surfactant, a nonionic surfactant, an anionic surfactant, a cationic surfactant and an amphoteric surfactant can be used.

As the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamide, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene glycol ethylenediamine, polyoxyethylene-polyoxypropylene glycol Oxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene glycol fatty acid ester, propylene glycol fatty acid ester, glycerin fatty acid ester, pentaerythritol fatty acid ester,
Examples thereof include sorbitan fatty acid ester, sucrose fatty acid ester, and fatty acid ethanolamide.

As the anionic surfactant, fatty acid alkali salt, alcohol sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, polyoxyethylene alkylphenyl ether sulfate ester salt, fatty acid polyhydric alcohol sulfate ester salt, sulfated Examples thereof include oils, fatty acid anilide sulfate ester salts, petroleum sulfonates, alkylnaphthalene sulfonates, dinaphthylmethane sulfonates, alkyldiphenyl ether disulfonates, and polyoxyethylene alkyl ether phosphate ester salts.

Further, as the cationic surfactant, a weak cationic cationic surfactant, for example, alkylamine and its polyoxyalkylene adduct, for example, octylamine, dibutylamine, trimethylamine, oleylamine, stearylamine and its ethylene oxide are used. 5 to 15 mol adduct, propylene oxide 5
˜15 mol addition product and the like. Further, as a weakly cationic cationic surfactant, a polyoxyalkylene adduct of polyamines such as alkylenediamine and dialkylenetriamine which may be substituted with a higher alkyl group, for example, ethylenediamine, ethylene oxide such as diethylenetriamine 0 to 100 mol Additive or ethylene oxide 0 to 100 mol and propylene oxide 0-1
Block or random adducts with 00 moles, oleyl propylene diamine, and ethylene oxide 0-100 mole adducts of stearyl propylene diamine are mentioned. Further, as weakly cationic cationic surfactants, polyoxyalkylene adducts such as higher fatty acid amides, for example, oleic acid amide, stearic acid amide with ethylene oxide 5 to 15 mol adduct, propylene oxide 5 to
15 mol addition products and the like can be mentioned. Examples of the strong cationic cationic surfactant include decanoyl chloride, alkylammonium salt, alkylbenzylammonium salt, and alkylamine salt. Specifically, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, Examples thereof include distearyldimethylammonium chloride, stearyldimerbenzylammonium chloride, stearic acid diethylaminoethylamide, coconut amine acetate, stearyl amine acetate, coconut amine hydrochloride and stearyl amine hydrochloride. In the case of a cationic surfactant having a strong cationic property, conductivity increases when the temperature of use of the electrorheological fluid reaches a high temperature of about 100 ° C. Therefore, among the above surfactants, a weak cationic surfactant is used. Is preferable, and low conductivity can be maintained during operation in a wide temperature range from a low temperature range to a high temperature range.

The content of the surfactant in the electrorheological fluid is
0.01% to 10% by weight, preferably 0.1% by weight
It is preferable to use it in a proportion of up to 5% by weight, and if it exceeds 10% by weight, the conductivity becomes high, which is not preferable.

If necessary, an antioxidant, a corrosion inhibitor, an antiwear agent, an extreme pressure agent, an antifoaming agent, etc. may be added to the electrorheological fluid of the present invention.

The antioxidant is intended to prevent the oxidation of the electrically insulating liquid as well as the polarization promoting agents such as polyhydric alcohol and polyhydric alcohol partial derivative. As the antioxidant, it is preferable to use one that is inactive to the polarization promoter and the dispersoid, and a commonly used phenol-based or amine-based antioxidant can be used. -6-di-t-butylparacresol, 4,4'-methylenebis (2.6-di-
t-butylphenol), 2,6-di-t-butylphenol, etc., and dioctyldiphenylamine, phenyl-α-naphthylamine, alkyldiphenylamine, N-nitrosodiphenylamine, etc., can be used as the amine type, and the whole electrorheological fluid can be used. On the other hand, 0.01 wt% to 10 wt%, preferably 0.1 wt% to 2.0 wt% can be used. If it is less than 0.01 wt%, there is no antioxidant effect, and 10 wt% is added. If it exceeds the above range, there are problems such as deterioration of hue, generation of turbidity, generation of sludge, and increase in viscosity.

Although a corrosion inhibitor may be added, it is preferable to use one which is inert to the polarization accelerator, dispersoid, etc.
Specifically, for nitrogen compounds, benzotriazole and its derivatives, imidazoline, pyrimidine derivatives, etc., for compounds containing sulfur and nitrogen, 1.3.4-thiadiazole polysulfide, 1.3.4-thiadiazolyl-2.5-bisdialkyldithiocarbamate, 2- ( Alkyldithio) benzimidazole, etc., and β- (o-carboxybenzylthio) propionnitrile, propionic acid, etc. can be used, and 0.001% by weight to 10% by weight, preferably 0.001% by weight to the whole electrorheological fluid, 0.01% by weight to 1.0
Use by weight%. If it is less than 0.001% by weight, there is no corrosion preventing effect, and if it exceeds 10% by weight, there are problems such as deterioration of hue, generation of turbidity, generation of sludge, and increase in viscosity.

[0038]

The electrorheological fluid of the present invention is excellent in stability at high temperature by blending a polyhydric alcohol in an electrorheological fluid in which solid particles, particularly silica gel is dispersed in silicone oil. The current value can be made relatively small, and by adding amino-modified silicone as a dispersant at a ratio of 80% by weight to 600% by weight with respect to silica gel, excellent dispersibility and excellent electrorheological effect can be obtained. And is useful as an electrorheological fluid that can be used in direct contact with a rubber-like elastic body, especially natural rubber.

The present invention will be described below based on examples.

[0040]

Example 1 An electrorheological fluid having the following composition was prepared.

(1) Silicone oil (polydimethylsiloxane, 25 ° C., 10 cSt) 57 wt% (2) Triethylene glycol 3 wt% (3) Silica gel (particle size 1.4 μm, product Name: Syloid 150, manufactured by Fuji Devison Chemical Co., Ltd .... 15% by weight (4) Amino-modified silicone (25 ° C., 1100 cSt, trade name: KF8002, manufactured by Shin-Etsu Chemical Co., Ltd.) 25 weight%

[0042]

Example 2 In the electrorheological fluid of Example 1, the same amount of ethylene glycol was used instead of triethylene glycol, and an electrorheological fluid was prepared in the same manner.

[0043]

Example 3 In the electrorheological fluid of Example 1, the same amount of tetraethylene glycol was used instead of triethylene glycol, and an electrorheological fluid was similarly prepared.

[0044]

Example 4 In the electrorheological fluid of Example 1, the same amount of pentaethylene glycol was used instead of triethylene glycol, and an electrorheological fluid was prepared in the same manner.

[0045]

Comparative Example 1 In the electrorheological fluid of Example 1, the same amount of water was used instead of triethylene glycol, and an electrorheological fluid was prepared in the same manner.

The electrorheological fluids prepared in the above-mentioned Examples 1 to 4 and Comparative Example 1 were put in a double cylinder rotary viscometer,
AC100V is applied between the inner and outer cylinders at 100 ° C, the axial force (torque) at the same shear rate (628sec ^-1 ) is measured, and the ratio to the axial force (torque) when no voltage is applied (thickening ratio) Was measured. At the same time, the current density (μA / cm ² ) in each electrorheological fluid when AC 1000 V was applied was measured at 100 ° C. The results are shown in Table 1.

[0047]

[Table 1]

The electrorheological fluid prepared in Comparative Example 1 could not be applied with 1000 V AC due to excess current.

As can be seen from the table, the electrorheological fluid of the present invention has a small amount of current and a high thickening factor.

[0050]

Comparative Example 2 An electrorheological fluid having the following composition was prepared.

(1) Silicone oil (polydimethylsiloxane, 25 ° C., 10 cSt) 57% by weight (2) Triethylene glycol 3% by weight (3) Silica gel (particle size 1.4 μm, product Name: Syloid 150, manufactured by Fuji Devison Chemical Co., Ltd .... 15 wt% (4) Oleylamine 25 wt% Electrorheological fluid prepared in Example 1 above and Comparative Example 2 With respect to the prepared electrorheological fluid, the double cylinder rotary viscometer was used and the temperature was changed to 40 ° C in the same manner, and the viscosity when no voltage was applied and the thickening factor when AC1000V was applied were measured. It measured similarly. The results are shown in Table 2.

[0052]

[Table 2]

The electrorheological fluid prepared in Comparative Example 2 and using oleylamine as the dispersant had a high 0V viscosity and a low thickening ratio, whereas the electrorheological fluid of the present invention used as the dispersant. It can be seen that by using the amino-modified silicone, the 0V viscosity can be lowered and the thickening ratio can be increased.

[0054]

Comparative Example 3 An electrorheological fluid having the following composition was prepared.

(1) Silicone oil (polydimethylsiloxane, 25 ° C., 10 cSt) 72 wt% (2) Triethylene glycol 3 wt% (3) Silica gel (particle size 1.4 μm, product Name: Syloid 150, manufactured by Fuji Devison Chemical Co., Ltd .... 15% by weight (4) Amino-modified silicone (25 ° C., 1100 cSt, trade name: KF8002, manufactured by Shin-Etsu Chemical Co., Ltd.) 10 % By Weight The electrorheological fluid prepared in Example 1 above and the electrorheological fluid prepared in Comparative Example 3 were the same except that a double cylinder rotary viscometer was used and the temperature condition was changed to 40 ° C. Then, the viscosity when no voltage was applied and the thickening ratio when AC1000 V was applied were measured in the same manner. The results are shown in Table 3.

[0056]

[Table 3]

The electrorheological fluid prepared in Comparative Example 3 and containing a small amount of amino-modified silicone had a high 0V viscosity, was a semisolid, and had a low thickening ratio, while the electrorheological fluid of the present invention was used. It can be seen that the fluid has a low 0V viscosity and a high thickening ratio by using amino-modified silicone as a dispersant.

[0058]

Example 5 An electrorheological fluid having the following composition was prepared.

(1) Silicone oil (polydimethylsiloxane, 25 ° C., 10 cSt) 57% by weight (2) Triethylene glycol 3% by weight (3) Silica gel (particle size 1.4 μm, product Name: Syloid 150, manufactured by Fuji Devison Chemical Co., Ltd .... 15% by weight (4) Amino-modified silicone (25 ° C., 60 cSt, trade name: KF859, manufactured by Shin-Etsu Chemical Co., Ltd.) 25 % By Weight For the electrorheological fluid prepared in this Example 5, a double cylinder rotary type viscometer was used and the temperature was changed to 40 ° C. in the same manner, and the viscosity when no voltage was applied and the AC10
The thickening ratio when 00V was applied was similarly measured. The viscosity when no voltage is applied is 1200 cSt, the thickening factor is 1.5, and the 0 V viscosity is higher than that of the electrorheological fluid prepared in Example 1, but is higher than that of the electrorheological fluid prepared in Comparative Example 1. Then, it can be seen that the thickening ratio is high.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C10M 125: 26 129: 08 129: 16 155: 02) C10N 20:06 40:14 (72) Invention Person Masahiko Hayafune 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Prefecture Tonen Corporation Research Institute

Claims (1)

[Claims] 1. An electrorheological fluid in which solid particles are dispersed in silicone oil, wherein a polyhydric alcohol is blended and an amino-modified silicone is blended at a ratio of 80% by weight to 600% by weight with respect to the solid particles. An electrorheological fluid characterized by the following.