EP0953034B1 - Liquid composition and its use as magneto-rheological liquid - Google Patents

Description

The invention relates to a liquid composition characterized by a low Distinguishes sedimentation tendency for particulate solids dispersed therein, and the use of such a composition as a magnetorheological Liquid (MRF).

Magnetorheological fluids (MRF) are functional working media whose Flow behavior by applying a permanent or variable electromagnetic Field can be changed in wide areas.

MRF products are versatile in terms of application technology for both hydrodynamic or hydrostatic as well as lubrication tasks. Known application potential are in the areas of adaptive damping, coupling and programmable brake systems but also for fixing wear protection agents as well as a sealing medium for moving shafts.

The composition of known experimental magnetorheological fluids basically consists of a carrier liquid, ferromagnetic particles as well as optional additives to improve certain application technology Properties of the respective products. In particular, additive components needed to prevent sedimentation or centrifugal ejection of the to minimize specifically heavy magnetic particles. The state of the art for Such additives can be selected, for example, from the PCT application PCT / US 93/09939 (WO 94/10693) can be removed.

According to the state of the art, synthetic base liquids are mostly used Media such as silicones or polyglycols are used. These liquids are often with the working fluids that are predominantly used in industrial practice based on mineral oil are not compatible and are therefore of many Areas of application excluded.

Furthermore, the liquids mentioned require very special, not universally applicable Additives, which inevitably leads to excessive costs and in itself unnecessary Variety leads.

The additive components used for the synthetic base liquids mentioned above have a when used in hydrocarbon base liquids insufficient stabilization with regard to the sedimentation tendency of the particulate Ingredients. The object of the invention is based on the object Fix disadvantages.

This object is achieved by the features of claim 1. Surprisingly, it was found that by using a special liquid composition optimal properties with regard to sedimentation tendency the particulate components, the flow behavior and the magnetorheological Properties of the liquids can be achieved. The liquid composition can be described as a stable suspension in which the particles are permanently dispersed.

Komponente A

einen Kohlenwasserstoff als Basisflüssigkeit, als

Komponente B

einen oder mehrere partikuläre Feststoffe, wobei der mittlere Durchmesser der Partikel kleiner 50 µm ist, und als

Komponente C

eine Polyharnstoffverbindung, die mindestens 3 und höchstens 20 -NH-C(=O)-NH- Gruppen aufweist als Verdicker.

Weiterhin können fakultativ die Komponenten D und E enthalten sein.

Komponente D

ist ein partiell verestertes Polyol als Dispergiermittel und

Komponente E

ein Acrylester- und/oder ein Methacrylesterpolymer als Viscositätsindex-Verbesserer.

The liquid composition according to the invention contains as

Component A

a hydrocarbon as the base liquid , as

Component B

one or more particulate solids , the average diameter of the particles being less than 50 μm, and as

Component C

a polyurea compound which has at least 3 and at most 20 -NH-C (= O) -NH- groups as a thickener.

Components D and E may optionally be included.

Component D

is a partially esterified polyol as a dispersant and

Component E

an acrylic ester and / or a methacrylic ester polymer as a viscosity index improver .

The optional additional components D and E interact with the essential components A, B and C and allow targeted, depending on the application dependent adjustment of the rheological flow behavior while maintaining or further improve sedimentation stability.

The respective application concentrations for the components of the basic additive system depend on the intended application and the corresponding magnetic particle content of the MRF. In addition to component A, the composition advantageously consists of: prefers to from the component 10 to 95% by weight, 25 to 90% by weight,
(particularly preferably 55 to 85% by weight) B or; 1 to 70% by weight, 2 to 40% by weight, B if B is not a metal powder; 0.05 to 4% by weight 0.1 to 3% by weight,
(particularly preferably 0.1 to 2% by weight) C or, 0.5 to 40% by weight, 1 to 30% by weight,
(particularly preferably 1 to 20% by weight) C based on the addition of SRI / 2; 0 to 6% by weight, 1 to 4% by weight, D and 0 to 20% by weight, 2 to 15% by weight, E, based on the liquid composition, the components A to E add up to about 100 particularly advantageously (the preferred percentages by weight apply independently of one another).

Component A is a hydrocarbon as the base liquid. A hydrocarbon compound For the purposes of this invention, a compound that is predominant (> 90 atom%, better> 95 atom%) from carbon and hydrogen atoms consists. These are, for example, mineral base oils or mineral oil-miscible, synthetic hydrocarbon oils such as hydrocrackates and polyalphaolefins or also long-chain esters (carbon chain = acid + alcohol> C12). The base liquid / The base liquid mixture is preferably not easily evaporating and has a boiling point greater than 100 ° C. Hydrogenated spindle oils are mentioned (Hydrocarbon mixtures, e.g. commercial products Tanex DN7, DEA) or Solvent refinates (hydrocarbon mixtures, e.g. commercial products Panax 19, Nepos 6, both from Dea). Furthermore, conventional commercially available hydraulic or called transmission fluids of type ATF (Automatic Transmission Fluid), some of which already contain the optional components D and E. Exemplary the commercial products Deafluid 1585 (ATF type TASA) are mentioned here, Deafluid 4011 (ATF type Dexron IID) Deafluid 3000 (ATF type Dexron III) and the development product DES-5999 (ATF type Dexron III), all products of the DEA.

ca. 85-92% Gew.%

Solventraffinat, parafinbasisch

ca. 2 bis 6 Gew.%

VI-Verbesserer auf der Basis von Polymethacrylat mit Dispersantfunktion

ca. 4 bis 8 Gew.%

eines Additiv-Paketes, wovon neben Antioxidantien, Korrosionschutzzusätzen, Verschleißschutzzusätzen, Reibwertverbesserern ca. 0,5 bis 3,5 Gew.% Dispersant-Zusätze darstellen, die von der Wirkung her ähnlich der Zusatzkomponente D sind.

Hydraulic or transmission fluids of the ATF type have the following typical composition, for example:

approx. 85-92% wt%

Solvent raffinate, paraffin-based

approx. 2 to 6% by weight

VI improver based on polymethacrylate with dispersant function

approx. 4 to 8% by weight

an additive package, of which, in addition to antioxidants, corrosion protection additives, wear protection additives, friction coefficient improvers, represent approximately 0.5 to 3.5% by weight of dispersant additives which are similar in effect to the additional component D.

Component B is one or more particulate solids, the mean diameter of the particles being less than 50 μm. In particular, about transition metals and / or transition metal compounds. The term “transition metal compounds” in the context of the invention includes alloys which contain transition metals. Transition metals in the sense of the invention are the elements with atomic numbers 21 to 30, 39 to 48, 57 to 80 and greater than 89. Transition metals / transition metal compounds in metallic or oxidic form are preferred. However, those transition metals and / or transition metal compounds which have magnetic properties (paramagnetic, superparamagnetic, but in particular ferromagnetic) are particularly preferred, in particular Fe, Co and / or Ni are mentioned. The particulate solids preferably have an average diameter of 0.5 to 20 μm. Iron / iron oxide powders have proven to be preferred. These can have a silica coating, for example. Carbonyl iron powders with a low carbon, nitrogen and / or oxygen content post-treated in particular have proven to be suitable.

Carbonyl iron powders from BASF AG are e.g. the SQ series or CN series, Whiskers A 234 (Fe whiskers) or ferrite material from BASF AG or Kaschke KG, Göttingen (Sr, Mn and Mn / Zn ferrite).

In addition to these metallic powdery solids, there are also others particulate solids in the liquid compositions of the invention excellently suspended. Molybdenum disulfide or graphite may be mentioned here. Such Liquid compositions are useful as lubricants among others also in combination with the ferromagnetic particulate solids.

Component C is a polyurea compound that has at least 3 and at most 20 -NH, C (= O) -NH- groups, preferably 3 to 8, particularly preferably 4 to 6. It acts as a thickener. With commercially available thickening concentrate based on the polyurea compound described above are excellent Sedimentation stability achievable. Those according to the invention are commercially available Polyurea compounds e.g. as ingredients in the lubricant SRI / 2 from Chevron. This contains the one to be used according to the invention Polyurea component to about 6 to 10 wt.% (≈ 8 wt.%).

n

eine ganze Zahl von 2 bis 19, vorzugsweise 2 bis 7, besonders bevorzugt von 3 bis 5 ist, und

x

für jedes n unabhängig voneinander ein zweibindiger Kohlenwasserstoffrest mit 1 bis 26 Kohlenstoffatomen ist, bevorzugt mit 2 bis 18 Kohlenstofatomen für den Fall, daß X aliphatisch ist, und mit 6 bis 13 Kohlenstoffatomen für den Fall, daß X aromatische Kohlenstoffatome enthält, und

R',R"

' unabhängig voneinander Wasserstoff oder ein Kohlenwasserstoffrest mit 1 bis 30, vorzugsweise ein Kohlenwasserstoffrest mit 6 bis 20, Kohlenstoffatomen ist.

The polyurea compound according to the invention is in particular a compound of the type R '- [- NH-C (= O) -NH-X-] _n -NH-C (= O) -NH-R " in which

n

is an integer from 2 to 19, preferably 2 to 7, particularly preferably 3 to 5, and

x

for each n is independently a divalent hydrocarbon radical having 1 to 26 carbon atoms, preferably having 2 to 18 carbon atoms in the case where X is aliphatic and having 6 to 13 carbon atoms in the case where X contains aromatic carbon atoms, and

R ', R "

is independently hydrogen or a hydrocarbon radical having 1 to 30, preferably a hydrocarbon radical having 6 to 20, carbon atoms.

The hydrocarbon radical X or R 'or R "can be linear, branched, or cyclic be, as well as saturated, unsaturated or aromatic (including combinations), preferably linear and saturated and / or aromatic. Such polyurea compounds are described for example in US 3,242,210.

A nonionic surfactant based on partially esterified polyols is used as component D. This should have an HLB value (hydrophilic-lipophilic balance) between 1 to 9, preferably 2 to 6. Such surfactants are available on the market and act as dispersants. Sorbitan oleates are preferred.

The following are mentioned as examples of the additional component D (including proof of a possible commercial product): Commercial product Pentaerythritol dioleate Edenor® PDO Henkel Glycerol monooleate Priolube® 1407 Unichema Sorbitan monooleate Crill® 4 Croda Sorbitan sesquioleate Crill® 43 Croda

Component E consists of mineral oil-soluble polymers, which preferably have an N-dispersant function. Polymethacrylates, which are particularly preferably provided with functional amino, amide or imide groups as N-dispersant functions, are particularly suitable, as are commercially available, for example, as so-called viscosity index improvers for use in hydraulic and internal combustion engine operating materials. Polymer contents of <3% by weight in the liquid compositions lead to the formation of bulges on rotating shafts in terms of flow behavior. For such applications, the liquid additions should therefore be set to over 3% by weight of component E.

The polymethacrylates are mentioned as examples of the additional component E (including detection of a possible commercial product): Commercial product Plexol® 966, Rohm and Haas Viscoplex® 4800 Röhm Empicryl® PT1397 Albright + Wilson

Further optional additives of the composition according to the invention are commercially available soluble P / S wear protection components (phosphorus and / or sulfur compounds such as phosphoric acid esters, thiophosphoric acid esters or sulfurized Polyolefins) and / or additives such as molybdenum disulfide, graphite, antioxidants and / or anti-corrosion agents.

Object of this invention is thus a base additive system rstoffölen universal and flexible in connection with mineral base oils or mineral oil-miscible synthetic Kohlenwass e as Hydrocrackaten and polyalphaolefins can be used versatile and advantageous. The liquid composition preferably contains no water.

The spectrum of possible uses extends from the magnetically fixable lubricant with a fat-like consistency right down to the lowest hydraulic fluid Yield point for use in automotive shock absorbers.

The mineral base allows the technically very valuable use of conventional ones proven lubricant additives, especially for optimal adjustment the frictional wear protection properties and the corrosion protection behavior the MRF. It is also possible to use commercial applications that are already in use optimized lubricating oils / substances as raw material for an additional Introduction of the specific MRF components. Examples are selected Greases, damping fluids or gear fluids.

Embodiments

65 Gew.%

naphth. Mineralölschnitt mit einer Viskosität von 6 mPa.s bei 20 °C

25 Gew.%

Carbonyleisenpulver (CEP) mit einer mittleren Korngröße von 5µm,

10 Gew.%

einer handelsüblichen Verdicker-Komponente entsprechend Beispiel.

The examples of series 1 to 9 (Tab. 1) show the surprisingly positive effect of the polyurea thickener based on a tetrapolyurea compound (formula I with n = 3) (Example 9,% by weight based on the addition of SRI / 2) compared to other thickeners and in particular the superiority over a standard polyurea (example 8, PU thickener Bechem M-02). All examples of this series are composed as follows:

65% by weight

naphth. Mineral oil cut with a viscosity of 6 mPa.s at 20 ° C

25% by weight

Carbonyl iron powder (CEP) with an average grain size of 5 µm,

10% by weight

a commercially available thickener component according to the example.

The mixture components are first mixed manually and then with one Intensive mixer homogenized over a period of 10 minutes. The mixing temperature reaches a height of about 60 ° C to 70 ° C with this procedure. The sedimentation behavior of the respective preparation is determined using a screening test by temporal observation of the phase separation in a graduate Measuring cylinder detected. Document the sample blends from the second test series (Tab. II) the interrelationships of the thickening component according to the invention (example 9) with optional surfactant and polymer additives.

The carbonyl iron powder (CEP) content for these examples is 50% by weight. The percentage of each additional component is shown in Example Table II remove. The remaining part of the weight consists of the naphthenic Mineral oil cut according to example series 1. The test for sedimentation stability is now being extended to a period of 90 days.

However, compositions with a higher proportion of carbonyl iron powder are also possible and advantageous (Example 22): Base oil % By weight fat Wt% CEP % By weight Additive in oil % By weight DES5999 10 SRI / 2 5 SQ 6397 85 OS 109939 11

The tabular information is supplemented by examples with complete flow curves (see Graph 1). The flow behavior of the samples is determined using a rheometer (from Physika) with regard to the yield point (Pa ₀ ) and shear stress at a shear rate of D = 1/1000 (Pa 1/1000) and the dynamic viscosity (mPas) at a shear rate of D = 1/500 specified. The surprisingly clear variability of the respective flow behavior through the additional components D and E can be demonstrated in the examples shown in graph I using the different flow curves (liquid composition with a constant 15% by weight SRI / 2).

The flow behavior of the liquid composition is shown in Graph II Example 22 in the magnetic field - measured by means of a rotary viscometer. The magnetic field was generated by a coil with a core, which is in a lower plate was integrated. The field strength actually generated was not measured, but only compared based on the voltage in volts applied to the coil.

Non-ferromagnetic materials can also be permanently dispersed according to the invention. Liquid compositions with the following composition (data in% by weight) were examined (left). The sedimentation behavior remained stable over 42 days (measured at room temperature). The shear stress (T in Pa) was determined at 40 ° C using the shear rate D (right): DSM-01 DSM-02 DSM-01 DSM-02 ATF (DES-5999) 73 78 1 s ^-1 2.14 4.37 SRI / 2 15 15 500 s ^-1 102 105 Crill 43 2 2 1000 s ^-1 89 91 MoS ² - 5 graphite 10 - MRF - example blends A 25% by weight CEP Example No. Thickener type Sedimentation stability [%] % By weight 24 hours 48 h 14 d 1 - 0 10 10 10 2 Sodium soap 10 12th 10 10 3rd Lithium soap 10 60 56 54 4th Ca - 12 - hydroxy soap 10 80 64 40 5 Ca - complex soap 10 86 80 48 6 Li - complex soap 10 84 76 44 7 Bentonite thickener 10 16 14 12th 8th Polyurea thickener (standard) 10 56 50 36 9 Polyurea Thickener (Invention) 10 96 94 70 MRF - example blends B 50% by weight CEP Example No. Thickener% by weight % Surfactant Polymer weight% Flow behavior Sedim.-Stab. after 90 d% Pa D = 0 Pa D = 1/1000 mPa.s D = 1/500 10 0 0 0 ----- not measurable ----- not stable - 11 15 0 0 18th 59 47 74 12th 17th 0 0 65 93 138 96 13 15 2 0 100 104 162 90 14 15 2 1.5 107 128 207 94 15 15 2 3.0 94 148 223 92 16 15 2 5.0 66 176 250 86 17th 15 2 10 32 214 262 82 18th 15 2 15 23 280 325 84 19th 10 2 15 31 316 378 96 20th 14 2 15 79 490 618 100 21 15 2 10 44 253 311 92

Claims (14)

1. A fluid composition comprising

   (A) one or more hydrocarbon compound(s) as a base fluid

   (B) one or more particulate solid(s), the average diameter of the particles being less than 50 µm

   (C) one or more polyurea compound(s) with at least 3 and not more than 20 -NH-C(=O) -NH- groups.
2. A fluid composition according to claim 1,
   characterized in that
   the boiling point of the base fluid is higher than 100 °C.
3. A fluid composition according to any one of the preceding claims,
   characterized in that
   the average diameter of the particles is less than 20 µm.
4. A fluid composition according to any one of the preceding claims,
   characterized in that
   the average diameter of the particles is greater than 0.5 µm.
5. A fluid composition according to any one of the preceding claims,
   characterized in that
   the polyurea compound is a compound of the type R'-[-NH-C(=O)-NH-X-]_n-NH-C(=O)-NH-R" wherein

   n

   is an integer of from 2 to 19, most preferably 2 to 7, and

   X

   is independently for each n a divalent hydrocarbon having 1 to 26 carbon atoms, and

   R',R"

   are independently hydrogen or a hydrocarbon having 1 to 30 carbon atoms.

6. A fluid composition according to any one of the preceding claims,
   characterized in that
   the solids are transition metals and/or transition metal compounds.
7. A fluid composition according to any one of the preceding claims,
   characterized in that
   the solid(s) is (are) or comprises (comprise) Fe, Co, and/or Ni.
8. A fluid composition according to any one of the preceding claims,
   characterized in that
   the solid(s) is (are) or comprises (comprise) iron and/or iron oxide.
9. A fluid composition according to any one of the preceding claims,
   characterized in that
   the solid is a particulate solid in the form of carbonyl iron/iron oxide powder.
10. A fluid composition according to any one of the preceding claims,
    characterized in that
    said composition furthermore comprises a nonionic surfactant based on partially esterified polyols (component D).
11. A fluid composition according to any one of the preceding claims,
    characterized in that
    said composition furthermore comprises an acrylate polymer and/or methacrylate polymer (component E).
12. Fluid composition according to any one of the preceding claims,
    characterised in that
    said composition besides component A comprises

    1 to 95 % by weight of the component B,

    0,05 to 4 % by weight of the component C,

    0 to 6 % by weight of the optional component D

    and 0 to 20 % by weight of the optional component E based on the weight of the fluid composition.
13. Use of the fluid composition according to one of the preceding claims as a magnetorheological fluid.
14. Use of the fluid composition according to any of the claims 1 to 12 in power transmission devices, wherein the fluid in the device shows variable rheological properties depending on the magnetic field applied.

Images