JPH02292393A - Electro-rheological fluid composition, granular material, and manufacture thereof - Google Patents

Abstract

PURPOSE: To prevent a remarkable decrease with an increase in shear rate thereby making it possible to use it in a dynamic electrorheological fluid device by dispersing a specified aluminosilicate in a fluid vehicle having a high electrical resistance.

CONSTITUTION: An aluminosilicate (A) consisting of a part represented by formula I [wherein b and c are each an arbitrary number, provided that b:c = 1:(1 to 9)], a mono- or divalent main-group metal cation, a hydrogen ion or an optionally substituted ammonium ion, and a nonaqueous polar adsorbent, [e.g. a crystalline zeolite of formula II (wherein M is a mono- or divalent main-group metal cation, a hydrogen ion or an ammonium ion; Q is a nonaqueous polar adsorbent; a is 1 when M is divalent, and 2 when M is monovalent; and b', c' and d are each an arbitrary number, provided that b'/c' is less than 1 and that c' is greater than 1)], is dispersed in a fluid vehicle (B) having high electrical resistance.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides electrorheological (EV) fluid compositions.
vis-cous (EV) fluid compos
(This is an electrorheological (ER) fluid.
(ER) fluid)]
and its manufacturing method. The invention further provides an electrorheological fluidic device.
l fluid appasatus) (ER device),
That is, an electrorheological (II:R) fluid undergoes virtual solidification when an electric field is applied against a shear stress applied to the fluid.
The above-mentioned ER in a device that operates using the occurrence of
Concerning the use of fluid compositions.

An example of an ER device is a driving surface (driving surface).
ving surface) and the driving surface (
A device that transmits force by the solidified fluid against the shear stress applied to the fluid between the fluid and the driven surface, such as torque transmission in an ER clutch,
There are devices for transferring force through solidified fluids, and for resisting the shear stress of hydrodynamic pressure acting on solid plugs, such as ER dampers using ER fluids. An example of this is a device that closes a valve by transmitting force by solidifying a fluid.

ER devices are commonly known and the electric field applied when using such devices is typically d. c.
(DC) electric field.

A dispersion is a dispersion made by dispersing an organic polymer containing acid groups in the form of a salt in a fluid with high electrical resistance.
EV fluid compositions are known for example for hydraulic clutches or dampers.

d. c, conventional d. applying an electric field. c. In ER equipment, the static yield stress (st
(attic-yield stress) increases as the applied electric field strength increases, and therefore ER fluids are used when the fluid is “locked-on” and is “solid”. For example, it is useful as a torque transmitter in a clutch.

However, ER fluid requires some d. c. For fluids that seem to require electrical conductivity. dielectric breakdown value (break
In a strong electric field greater than d. c. The electrical conductivity increases significantly and arcing occurs through the ER fluid.

Conventional ER fluids typically have a
tage) is relatively low.

The low yield stress/applied electric field strength ratio described above means that the ER fluid has a relatively large potential gradient (
gradient) must be applied and the surface area facing the opposing electrodes for applying the electric field must be large and the two electrodes must be close to each other. This and
relatively d. c. The high electrical conductivity actually results in undesirably high power consumption and thus overheating of the device (conversion of electrical energy into thermal energy).

ER devices, such as ER clutches and dampers, often operate at moderately high operating temperatures (e.g. 50°C) due to electrical heating and, in the case of dampers, conversion of absorbed mechanical energy into heat. above).

ER fluid d. c. Conductivity increases significantly and even exponentially with temperature, resulting in a continuing vicious cycle of increased power consumption and increased device temperature in actual use. Ru. Typically,
d. c. Such an ER fluid within the device is at its so-called doubling temperature.
) (ie, the operating temperature increment 2 that doubles the conductivity is about 6°C).

At moderate tolerable power consumption, extended operation of the ER fluid will not allow the equilibrium temperature to be reached below the temperature at which deterioration occurs, and may even exceed the deterioration temperature.

If temperature equilibrium does not occur below the breakdown condition for the fluid, d. c. The conductivity and power consumption will increase until the capacity capability of the power supply is exceeded and/or the ER device and/or
or increase until the fluid is no longer electrically operable.

A relatively high yield stress/applied electric field strength ratio and a relatively low d.
c. It would be desirable to provide an ER fluid with electrical conductivity and a relatively high breakdown voltage for use in static d.c. ER equipment.

ER fluids that have these properties have good static performance (
It is clearly useful for applications such as "locked-on" ER clutches where static performance is required.

In addition to the above, steady d. c.
, in an electric field, d. c. Conventional ER fluids within devices have a dynamic shear stress of the fluid.
r stress decreases significantly with shear rate and can even decrease exponentially with shear rate; similar) and often have poor dynamic performance (d
ynamtcperformance).

Such d. c. Such ER fluids in devices are clearly of limited use in applications such as ER dampers where the ER fluid already under shear is required to have good dynamic ER performance.

An ER fluid having a relatively high shear stress/applied electric field rate ratio, a relatively low electrical conductivity, and a relatively high breakdown voltage that does not decrease significantly with increasing shear rate.
It would be desirable to provide an ER fluid for use in dynamic ER device applications.

According to the findings of the present inventors, a. C. (police box)
Certain ER fluids used under the application of an applied potential are particularly sensitive to this a. C. It has been found that the above-described desirable properties are present when at least one of the electrodes used to apply the potential is insulated from the fluid. That is, for example, the ER fluid used in such dynamic ER device applications may have a shear stress that increases as the shear rate increases.
It has good dynamic performance in that it increases slightly and perhaps even significantly.

Such ER fluids are clearly useful in applications such as ER dampers where good dynamic performance is required.

The invention may be a) static and/or d. c. and/or b) dynamic and/or a. c. To provide an ER fluid that can be used in applications where the ER fluid is used and does not have the above-mentioned drawbacks.

According to the invention, therefore, non-aqueous polar adsorbate (adser
high alumina exchanger alumina silicate containing
An ER fluid composition is provided that comprises a dispersion of ate) dispersed in a highly electrically resistive fluid vehicle.

As used herein, “adsorbate” (“adsor-
The term adsorbed on and/or into an aluminosilicate structure
, coordinate and/or absorb
sorbed) means any substance that is sorbed.

As used herein "exchanger aluminosilicate"("ex
changer aluminosilicate
) is defined as: a) Empirical formula: (Al sOa)b(SjOt)c (b and C in the formula are arbitrary numerical values, provided that b/c
The ratio of moiety shall not exceed l.
) ; and b) monovalent or divalent main group
It means any inorganic material consisting of a metal cation, a hydrogen ion or an optionally substituted ammonium ion.

In some of these inorganic materials (exchanger aluminosilicates), ions are exchangeable.

The inorganic materials include, for example, zeolites, mica, and vermiculite; the inorganic materials can be natural or synthetic, and the materials can be commercially obtained or derived from such materials. For example, it can be induced by ion exchange. Furthermore, the cations in this inorganic material are composed of a mixture of two or more cation species, and the ratio of these cation species can be infinitely variable.
e) Is it a mixture? Machinery materials are also included.

The term "high alumina" means any exchanger aluminosilicate having a b:c ratio in the range 1:1-1+9. Preferably it is a crystalline material. Examples of high alumina exchanger alumina silicates are given below.

The particulate dispersed phase used in the EV fluid of the present invention
The exchanger alumina silicate contained in the dispersed phase) is one of the subject matter of the present invention.

l7 Included within the scope of the aluminosilicates of the present invention:'zeolites have the empirical formula: Mac(AA'*Os)b■ (SiOt)c-Qa
(1) (wherein, M is a monovalent or divalent main group metal cation, hydrogen or ammonium ion; Q is a non-aqueous polar adsorbate; a is when M is divalent; l, and when M is monovalent, it is 2; b', c' and d are arbitrary numerical values, provided that b'/
The ratio of c' can exceed 1:l, and C
' shall not be less than or equal to 1).

Examples of aluminosilicates include natural and commercially available zeolites and materials obtained from these zeolites by ion exchange of Ma or direct exchange of water and Q. (
Zeolites are known ion-exchangeable and water-absorbing materials containing labile water. ) In the above definition, MaO is included in the definition.
Also included are materials which are mixtures of r or more O species and whose ratio of these MaO species can be varied infinitely.

The ER fluid of the present invention has good ER properties such as d. C. Good static yield stress/applied potential ratio for applied potential and/or a. C. Develops a good dynamic yield stress/applied potential ratio for applied potential.

"d.c." when used in connection with applied potential means an essentially constant applied potential.

When used in connection with an applied potential, "a.C." means a potential that can vary periodically in nature (either symmetrical or asymmetrical with respect to the O potential).

Suitable high alumina exchanger aluminosilicates in the fluids of the present invention include cationic salts, group IA or nA metals,
Mention may be made, for example, of lithium, sodium, potassium, magnesium or calcium or mixtures thereof, especially potassium or calcium.

Suitable high alumina/exchanger/aluminosilicates include:
Furthermore, examples include those in which the cation species is an nB group metal. Examples of such cations include zinc cations and mixtures of zinc cations and other suitable cations.

In the granular materials of the invention, the cations usually form 1 to 50% by weight of the dispersed phase.

In one group of exchanger aluminosilicates of interest, the ratio of b20 is from 1:1 to 1:5, in particular from 1:1 to 1:
It is 3.

The adsorbate in the aluminosilicate of the present invention is any one that can adsorb onto the structure of the exchanger/aluminosilicate, coordinate to the structure, and/or absorb into the structure. It can be a polar, non-aqueous adsorbate, and the adsorbate can be a pure gas or liquid or a mixture thereof or a solution of a gas or a polar solid, for example, and can be an inorganic or organic substance. obtain.

Typically the non-aqueous adsorbate is pure, but it can also be a non-aqueous solution of an inorganic salt.

Examples of such salts include salts of any of the above-mentioned cations with sulfuric acid or hydrochloric acid, or salts with organic carboxylic acids or sulfonic acids.

The exact physical state of the polar adsorbate adsorbed, coordinated and/or absorbed into the aluminosilicate structure is not clear.

However, suitable adsorbate capable of effecting such a bond include gases such as ammonia and alkylene oxides such as ethylene oxide and propylene oxide, and liquids such as polar organic liquids such as cyclic ethers such as tetrahydrofuran and dioxane. Mention may be made of acyclic amines such as ethylamine, engineered ethylene diamine and aniline, and cyclic amines such as pyrrolidone, piperidine, piperazine and morpholine.

Accordingly, the terms "gas" and "liquid" used in connection with the adsorbate in its standard state at room temperature and atmospheric pressure are used to describe the aluminosilicate of the present invention, as is customary for example for water-containing zeolites. It refers to all the physical states of the relevant adsorbate in the salt.

The amount of adsorbate contained in the aluminosilicate is typically 1-10% by weight of the dispersed phase when the polar adsorbate is water.
, preferably from 1 to 5% by weight, but this content can be varied within a very wide range, up to larger values, for example up to 30% by weight.

However, if the polar adsorbate content is greater than a certain value, the corresponding ER fluid's d. c. It was recognized that the disadvantage of increased electrical conductivity occurred.

As a result, power consumption and low applied d. c. The tendency for dielectric breakdown to occur under voltage increases; for example in the case of power consumption it increases by more than 50%. This results in good values of static yield stress/applied d. c. Even though the ratio of potentials tends to hold in the corresponding ER fluid (normal, static)
d. c. For applications, higher polar adsorbate contents than those mentioned above are precluded.

Therefore, d. c. For applications using applied potentials, preferred fluids have low d. c. electrical conductivity and therefore often have a low polar adsorbate content.

However, each suitable or optimal polar adsorbate content can vary over a wide range depending on the desired properties of the fluid, the particular dispersed phase, and the particular EV fluid vehicle.

However, the adsorbate content in each case can be determined by routine testing.

For example, preferred ER fluids for dynamic applications (devices) include rapid dynamic energization.
) with response time. Such a desirable rapid response time If often requires a higher d. c, conductivity and such higher d. c. Electrical conductivity can be imparted by increasing the content of polar adsorbate in the ER fluid dispersed phase.

polar adsorbates and/or their respective associated dispersed phase particles and/or
or the dispersed phase or particulate converter aluminosilicate is encapsulated from the remainder of the EV fluid, for example by a hydrophobic fluid, gel or wax insoluble in the vehicle of the corresponding EV fluid of the invention or by a surface layer of coke.
e) If L, then d. c. Higher polar adsorbate content (and thus higher d.c., conductivity) is also acceptable for applications using applied potentials.

As mentioned above, for dynamic applications, a. C. It is often preferred to use an applied potential.

In such applications, the d. c. Conductivity and the associated power loss do not have much of an impact.

This applies in particular if at least one of the electrodes applying the potential is insulated from the fluid. When the fluid of the invention is used according to this method with a constant applied (d.c.) potential applied between the electrodes, no RE effect is observed; The resistance causes the conduction of current to be limited and the very small amount of current flowing through the fluid will be insufficient to cause an ER effect.

When a periodically varying (i.e., "a.c.") potential is applied between electrodes that are insulated from each other, the current induced in the ER fluid is sufficient to produce the ER effect. .

This ER effect has the same d. c. Comparable to that obtained when using electric potential. However, an apparent current flows through the fluid in use, the magnitude of which is the d. c.
It is limited by the impedance of the device rather than by resistance.

Therefore, the power consumption for uniform shear stress is usually reduced, resulting in a d. c. The effect of conductivity on power consumption is controlled.

In particular, if the dispersed phase of the ER fluid is insulated from the rest of the associated electrical circuit by an insulator on at least one of the electrodes, such a. C. Higher polar adsorbate contents for applied potentials may be acceptable and even preferred.

However, it is generally preferred that the total polar adsorbate content of the dispersed phase exchanger aluminosilicate be 10% by weight or less.

In all of the exchanger aluminosilicates of the present invention, polar adsorbates are often exchangeable and adsorbate-free materials (
(including non-water containing materials) i) equilibrated with the relevant polar adsorbent or air as a gas or liquid at the desired vapor partial pressure for the non-aqueous adsorbate, or ii) of the dispersed phase of the ER fluid or its components. can be regulated by equilibration with a fluid vehicle having a controlled non-aqueous polar adsorbate content.

Typically, adsorbate-free materials are prepared by thoroughly drying a corresponding water-containing material (eg, an at least partially hydrated material).

Such drying is usually carried out under heat and/or reduced pressure and optionally in the presence of a desiccant such as P,0.

As will be described later, such special particles of the particles (particulate material) of the present invention are preferred, especially as compared to larger particles, drying times are shorter.

Certain high alumina exchanger aluminosilicates include, for example, the exchange of water indirectly with a non-aqueous polar adsorbate Q as shown in formula (I) and, if necessary, M according to conventional methods.
By performing ion exchange of a, zeolites A and
(manufactured by Union Cabide) and Y (Stre
Examples include zeolites such as the materials for the fluids of the present invention, which may be derived from zeolites (products of the Company M). Then, for example,
In the A series derivatives, sium, Ca (zeolite 5A
).

Similarly, Nat in the zeolite X derivative can be exchanged with the same cation if desired. Of course, "mixed" zeolites within the scope of the present invention may be prepared by exchanging Ma with two or more ions. These zeolites have a cubic particle structure (cubic parti
cle morphology).

Preferred exchanger aluminosilicates as the dispersed phase or component of ER fluids have low d. c. Examples include those having electrical conductivity. Such exchanger aluminosilicates have reproducible and controllable operating parameters and good static yield stress and/or dynamic shear stress/applied d. c. or a. C. Provides a fluid with high voltage ratio and low power consumption.

Such materials (exchanger aluminosilicates) are static and/or d. c. Especially suitable for operation. This is especially true for d. c. This can be said in terms of the high breakdown voltage of the corresponding EV fluid in operation.

In addition to these exchanger aluminosilicates, which generally have a low non-aqueous adsorbate content (this adsorbate content is similar to that mentioned above as being the preferred adsorbate content), the exchanger As aluminosilicates, mention may be made of zeolites of the formula (I) in which MaO is CaO, in particular zeolite 5A derivatives.

Preferred exchanger aluminosilicate dispersed phases or other preferred groups of exchanger aluminosilicate components of such dispersed phases have good static yield stress and/or dynamic shear stress/applied d. c. or a. c. It provides a fluid with a ratio of voltages.

Such a temperature is, for example, a temperature of 40°C or higher, for example, a temperature of 50°C or more.
It can be 100°C or 50-150°C.

The dispersed phase or components of such ER fluids are such that either the fluid itself normally has such high temperatures (e.g. due to the heat generated in the fluid when used as a clutch fluid) or the fluid used normally has such high temperatures. preferred for use in several typical operating environments.

As such exchanger aluminosilicate, in the above formula CI), MaO is K. Mention may be made of zeolites which are O, in particular the zeolite 3A (potassium) derivative; this zeolite has a low polar adsorbate content similar to that indicated above as desirable as a polar adsorbate content.

As mentioned above, the electrical conductivity of the ER fluid dispersed phase (especially d.
c. conductivity) tends to increase with increasing temperature;
As a result, power consumption increases and d. c. In operation with , the breakdown voltage decreases.

Therefore, good static yield stress and/or dynamic shear stress/
Application d, c. or a. C. Materials with a ratio of voltages (
There is a preferred group of materials within the range of exchangers (aluminosilicates).

Low d. even at elevated temperatures. c. There are materials that have electrical conductivity.

As such a material, as mentioned above, MaO is κ,0
Mention may be made of the exchanger aluminosilicates of the present invention, in particular the zeolite 3A derivatives.

Another group of preferred exchanger aluminosilicate dispersed phases or components of the dispersed phase have good yield stress and/or dynamic shear stress/d, c. over a wide temperature range. or a. C. Examples include those having a ratio of applied voltages.

Such a temperature range may be, for example, a temperature range used in a wide range of operating environments, i.e. 0 to 100°C or θ to 150°C.
It can be ℃.

Such materials include single zeolite materials of formula (I) where MaO is a mixture of two or more of the species included in the definition of MaO.

When different zeolite-type exchanger aluminosilicates are present in the EV fluid dispersion phase of the present invention and different species of MaO are present in the aluminosilicates, these exchanger aluminosilicates are present in the intermixture. present in each particle of the EV fluid dispersed phase in the form and/or as a coating with at least one present on at least the other, ie concentrated at and/or near the core surface.

Apart from this, the dispersed phase consists of a mixture of particle sets made of aluminosilicate.

In any of the above mixtures, two species of Ma
O is often used; in this case, one of the Ma
O is selected to exhibit better performance as it approaches the lower limit of the desired temperature range, while MaO is selected to exhibit better performance as it approaches the upper limit of the temperature range.

However, the selection of these MaOs will also be based on the thermal stability of the two materials (exchanger aluminosilicate) at the upper end of the temperature range.

Materials such as those described above will be determined by the particular application required, but may include, for example, MaO with a single species such as CaO and K,0 or two species such as CaO and K. Zeolite A containing both O
Mention may be made of derivatives or mixtures of zeolites 5A and 3A.

In any such material containing two MaO species, each of the two MaO species may be present in an amount of 1 to 99% and 99 to 1% by weight of the total MaO content, respectively.

The specific ratio will, of course, vary depending on the exact performance for the desired temperature conditions and the particular ions or materials used.

In all such species (exchanger aluminosilicate containing two types of MaO), the total adsorbate content of the dispersed phase is preferably similar to the values indicated as preferred for the aluminosilicates.

As mentioned above, most ER fluids have d. c. The electrical conductivity increases as its operating temperature increases to the extent that it becomes practically unusable under routine operating conditions. Included among these fluids are fluids that may have other desirable properties, such as rapid voltage application response times.

The inventors have prepared the fluid of the present invention by a. c. It has been discovered that the typical doubling temperature of many such fluids is significantly increased when used in an ER device.

This temperature doubling is typically from about 6°C to about 25°C.

This temperature increase increases the range of practical operating temperatures that can be reached by many such fluids without excessive power consumption.

Such materials therefore include materials in which the cationic species included in the range of MaO defined above is Ca.

Advantageously, any of the dispersed phase materials described above consists of at least one exchanger aluminosilicate and at least one other material.

Again, the components of the dispersed phase material are present in the form of an intermixture and/or as a coating in which at least one component is present on at least one other material, i.e. on and/or near the core surface. May exist in concentrated form. In the latter case, the exchanger aluminosilicate is often
It will be present as a surface component.

Said other material can be any material that is compatible with the exchanger aluminosilicate and so that the resulting dispersed phase is compatible with the properties of the vehicle and the desired properties of the corresponding EV fluid.

In the case of the latter materials, it is preferred that the alumina content and polar adsorbate content of the total dispersed phase be similar to the contents indicated above as appropriate and preferred for the exchanger aluminosilicate itself.

When the exchanger aluminosilicate is in an intermixture or is present as a coating on or core of another material in a dispersed phase or particle, the exchanger aluminosilicate content is usually that of the other material. It will be much larger than the content of the ingredients.

Its content can be, for example, from 8 to 100% by weight of the dispersed phase.

However, the optimal proportion of aluminosilicate (eg, zeolite) can vary quite widely from the above proportions, depending on the particular ER fluid. The optimum proportion of aluminosilicate may also vary widely from the proportions mentioned above depending on the particular desired EV effect. These optimal ratios can be easily determined by routine testing.

For all such dispersed phase materials, it is preferred that the total adsorbate content of the dispersed phase is similar to the contents indicated as preferred above.

Suitable other materials in the dispersed phase particles of the EV fluids of the present invention include conductors and conventional inert sheathing and core materials.

Conductors include, for example, carbon, e.g. coke coatings formed in situ on the aluminosilicate cores of the present invention (however, this conductor may disadvantageously make the corresponding EV fluid more conductive). (Less preferred for reasons of nuisance.) Inert materials include materials such as cellulose derivatives, alumina, and silica.

The dispersed phase may consist of a mixture of the dispersed phase particles and other particles, and preferably the other particles are capable of imparting ER properties to the fluid.

Such other particle types may, of course, contain polar adsorbate or different polar adsorbate. Preferably, any such adsorbate is a polar adsorbate.

Preferably, the total polar adsorbate content in the dispersed phase will be similar to that in Section 1' above.

If all particles of the dispersed phase contain unstable polar adsorbate, it is desirable that the polar adsorbate of the dispersed phase be essentially homogeneous with respect to the operational stability of the corresponding EV fluid.

Suitable materials among other particle types include organic ion exchange resins.

The proportion of the dispersed phase in the ER fluid compositions of the present invention is determined by the particular application of the composition and the vehicle used, since these determine the desired or acceptable viscosity. . Accordingly, the proportion of ER fluid that is the dispersed phase can be determined by routine testing.

However, generally the proportion of the dispersed phase will be 15-65% by weight of the total composition.

20-65% by weight, depending on the vehicle type, is suitable for many applications.

Higher or lower viscosities may be acceptable or necessary for certain applications, and therefore higher or lower proportions of dispersed phase may also be acceptable or necessary for certain applications. It is.

Higher proportions may also be used if the dispersed phase is surface treated or the vehicle has a very low viscosity or high operating temperatures are used; however, this reduces the non-uniform electric field (no - field) and/or the cold viscosity does not increase to an unfavorable or impracticable degree.

Relatively low d. c. or a. C. If a high static yield stress and/or dynamic shear stress is obtained at the potential gradient and/or current density, a lower proportion, e.g.
Proportions of 5 to 25% by weight may be suitable.

Such proportions may be appropriate when using the preferred fluids of the present invention in most suitable (static, dynamic, d.c. or a.c.) applications.

The dispersed phase particles of the fluid compositions of the present invention have a mean cross dimension of 0.1 to 50 microns, preferably 0.1 to 20 microns, especially 2 microns or less.
sion).

However, at the upper limit of the size range, this average width dimension
se 4ield gay).

This spacing should be at least 10 times the largest grain width dimension.

Particle width dimensions below 0.1 micron, on the other hand, are best avoided for the following reasons: a) have an undesirable effect on the physical properties of the corresponding EV fluid; and b) Dry dispersed phase typically has higher potential toxicity compared to larger particles
has.

It is advantageous that the viscosity analysis is narrow in order for the corresponding EV fluids of the present invention to have reproducible and controllable parameters.

Suitable vehicles or components thereof in the fluids of the invention include chlorinated C. one,. Examples include halogenated higher aliphatic compounds such as paraffin. This aliphatic compound is typically CIO-1t C14-1? tClg-
, S and Cl4-1. It is a hydrocarbon fraction such as These are typically 25-60% by weight, e.g. 29-33%
% and a chlorine content of 49-53%. An example of this is Cereclor;
CI company registered trademark) series. Suitable vehicle materials also include halogenated vinyl polymers, such as poly(trifluorovinyl chloride) (e.g. Fluorolube FS-5:
Hooker products] and perfluoropolyethers such as Fomblim (Monte
disioi product).

Lower aliphatic compounds such as cyclohexane, carbon tetrachloride and chloroform are also suitable as vehicle components.

Other suitable vehicles or components thereof include optionally substituted aromatic hydrocarbons such as toluene and xylene.

Certain aromatic vehicles that are less preferred because of their greater conductivity than the suitable vehicle components listed above include, for example, nitrobenzene, chlorobenzene, bromobenzene, and O-dichlorobenzene.

Aromatic vehicles further include p-chlorotoluene and polychlorinated biphenyl fractions, such as allocrel (Ar).
ocler) 1242 (registered trademark of Monsanto)
can be mentioned.

Silicones, especially substituted aromatic silicones such as polydialkylsiloxanes and bis(chlorinated phenyl) silicones, are particularly preferred vehicles or vehicle components. Examples include silicone oil C 111/50
(IC 1 product).

It will be appreciated that the initially mentioned halogenated higher aliphatic compounds and especially silicones are preferred because they are generally less toxic than other vehicles/components.

Any of the above vehicles may be used alone or as a mixture (to the extent that they are compatible).

It is preferred to optimize the dispersion of the ER fluid and to not unduly increase the viscosity of the composition due to the viscosity of the vehicle (which is related to density).

To achieve this objective, it is advantageous that the density of the vehicle does not differ significantly from the density of the dispersed phase; it is preferred that the two are matched in density. To accomplish this, the vehicle can be a mixture of at least two components, one component having a higher density than the dispersed phase and the other component having a lower density than the dispersed phase.

Since density and viscosity vary widely with temperature, the density matching should be performed at the desired operating temperature.

Preferred zeolite materials of the invention have relative densities of 1.5 to 2.2, and preferred vehicles have relative densities of 0.8 to 1.
It has a relative density of 3 (all at 25°C).

A static viscosity that uses a surface-treated (e.g., treated with a surfactant) dispersed phase and includes a gelling agent in the vehicle so that the ER fluid composition acts to prevent settling of the dispersed phase. dispersion can be optimized by having a low enough viscosity to be used as an ER fluid.

Although the ER fluid composition may also include a fluidizer such as sorbitan mono or sesquioleate, the viscosity of the ER fluid is preferably adjusted in the manner described above.

The invention also encompasses the use of the compositions of the invention as an EV fluid (eg, within an applied electric field in a hydraulic clutch or damper).

The preparation and use of such compositions as EV fluids is carried out according to conventional methods.

Exchanger aluminosilicates of the invention may be prepared according to the method of Example 1 below; compositions of the invention may be prepared according to the method of Example 2 below.

Generally, in the embodiments, the aluminosilicate is prepared by: a) essentially adsorbate-free (e.g., anhydrous) aluminosilicate at ambient temperature and pressure; Equilibrate with non-aqueous polar fluid (7,
guilib#ate) and then b) optionally partially removing the polar adsorbate from the above product. The starting aluminosilicate can be prepared from commercially available ion-exchanged aluminosilicates by ion exchange, washing and drying under heat and/or reduced pressure in a conventional manner.

The operating potential slope applied to the ER fluid of the present invention is between 1 and 20
, for example in the range from 2 to lOKVmm-'.

For dynamic applications, the applied potential is a.
C. It may be appropriate to be at an electric potential.

Such a. C. The potential can be varied in any manner that is periodic. That is, this potential can have any waveform with respect to the earth potential, such as a sine wave, a square or a sawtooth (triangle).
It can be a potential that varies in the form of .

The electric potential can also be a positive or negative electric potential that varies with respect to the earth potential, such as a pulsed d. c. (julse
dd. c. ).

A. has the same magnitude and waveform at any average potential with respect to the applied varying potential and the ground potential. C. potential or pulse D. C. No difference is observed in the ER effectiveness of a given ER fluid, regardless of potential.

As might be expected, the ER effect is caused by the application of a. c. Increases with potential gradient. Also, the ER effect increases with input power at a given maximum input potential. That is, given O
For maximum applied potential, the ER effect increases as the waveform changes from triangular to sinusoidal to square.

Suitable frequencies for periodically varying potentials will vary significantly depending on the ER system in which the ER fluid of the present invention is to be used.

For example, at medium and high frequencies, problems with skin effects, inductance, kick-up and transmission disturbances increase significantly. As a result, the need for rigorous screening of all electrical components increases significantly.

These engineering problems may be acceptable, for example, for dampers used in certain specialized applications (eg, for spacecraft), but not for automobiles.

Generally, the frequency is 1 to 6000Hz, for example 1 to 2
A range of 000 Hz may be suitable.

Generally applicable frequencies are usually 1-600Hz,
For example, 1 to 200Hz, preferably 3 to 150H
Z, especially from 5 to loOHz.

The inventors have found that, for example, in dynamic applications a. C. It has been observed that when using an applied potential, the fluids of the present invention exhibit significant maximum shear stress at certain frequencies.

The frequency exhibiting maximum shear stress may be another factor for determining the desired frequency of operation of the ER fluid of the present invention.

Such a frequency may actually be used to control the response of an E device that uses this frequency.

As noted above, in certain uses, the fluid of the present invention is applied between electrodes, at least one of which has an electrically insulating surface coating, a. C. A potential can be applied.

Here, the term "insulating surface coating" refers to
5 x 10-' ohms 1,c at 25°C for fluid
It means a coating on such an electrode that gives a conductivity of less than or equal to m-'.

As mentioned above, at the actual field frequency used, the ER effect will be the same under the same conditions. c. Comparable to that achieved using electrical potentials.

The ER fluid of the present invention includes a. C. A suitable device for applying an electric potential is disclosed in British Patent Application No. 8926065.
It is described in Specification No. 4.

The varying potentials may be applied by any suitable device capable of generating the required potentials, frequencies and waveforms.

Generally, the impedance is relatively high, and therefore, taking into account factors such as those discussed above, large power sources are generally not important in most practical ER applications.

Industrial high voltage signal generators may often be suitable.

Examples of the present invention are shown below.

Preparation of aluminosilicate for EV fluid according to the present invention is shown in Table 2. The zeolite below is Union Carbide
It is indicated by the company's product number.

Table I The following compositions were prepared by dispersing the zeolite in a vehicle in a conventional manner.

The yield stress of the composition and the current density at the yield stress with respect to the applied voltage across a gap of 0.5 m were measured.

This test was carried out on the rig described in British Patent No. 1,501,635 and in the manner described therein.

The performance of the ER fluid of the present invention may also be tested dynamically.

The device was of the ER clutch type and consisted of a pair of coaxially mounted cylindrical electrode clutch members: the outer clutch member was stationary and the inner clutch member was rotating.

The inner clutch member is a solid copper cylinder, optionally coated with an insulating paint; the inner clutch member is housed within an outer clutch member consisting of a hollow steel cylinder coaxially adjacent thereto. .

The dimensions of the clutch member may vary, but for example, the internal member may be 25.64 m long and 49 mm in diameter. 64 mm, optionally covered with an insulating coating of self-adhesive PvC tape 0.12 mm thick.

The outer member has a radial gap between the two members.
lP gay) when the PVC tape is not present on the internal member. 20 wun, and 1. when PvC tape exists. It has dimensions of 0.08 mm.

The ER fluid between the two electrodes was selected from the compositions shown in the previous examples.

The internal member is rotated under feedback control by a variable speed electric motor, and the transmitted torque is measured using a rotational torque transducer.

Claims (1)

[Scope of Claims] 1. An electrorheological fluid composition comprising a dispersion of an aluminosilicate dispersed in a fluid vehicle of high electrical resistance, wherein the aluminosilicate has a) the empirical formula: (Al_2O_3)_b( SiO_2)_c (b in the formula
and C are arbitrary numerical values, provided that the ratio of b/c is 1:
b) a monovalent or divalent main group metal cation, a hydrogen ion or an optionally substituted ammonium ion; and c) a non-aqueous, An electrorheological fluid composition comprising: a polar adsorbate. 2. The composition according to claim 1, wherein the aluminosilicate is crystalline. 3. Aluminosilicate has the empirical formula: MaO(Al_2O_3)_b_'(SiO_2)_c
___'Q_d(I) (where M is a monovalent or divalent main group metal cation, hydrogen or ammonium ion; Q is a non-aqueous polar adsorbate; a is 1 when M is divalent; and when M is monovalent, it is 2; b', c' and d are arbitrary numerical values, provided that b'/
The composition of claim 1, wherein the composition is a crystalline zeolite having a ratio of c' not greater than 1 and c' not less than 1. 4. The composition according to claim 3, wherein the cation comprises a Group IA or Group IIA metal. 5. The composition according to claim 4, wherein the cation is lithium, sodium, potassium, magnesium or calcium or a mixture thereof. 6. The composition according to claim 3, wherein the cation comprises a Group IIB metal. 7. The composition according to claim 6, wherein the cation comprises zinc or a mixture of zinc and other cations. 8. The aluminosilicate in the dispersed phase is 0.05 to 1% of the dispersed phase.
A composition according to claim 1 containing 0% by weight of ammonia or ethylenediamine. 9. Granular material for use as a dispersed phase in electrorheological fluids, consisting of an aluminosilicate containing a moiety of the empirical formula: (Al_2O_3)_b(SiO_2)_c according to claim 1. 10. By carrying out ion exchange of the aluminosilicate and optionally removing water from the aluminosilicate, it contains a moiety represented by the empirical formula: (Al_2O_3)_b(SiO_2)_c according to claim 1. Process for producing granular material according to claim 9, characterized in that an aluminosilicate is obtained.