EP0624185B1 - Homogeneous electroviscous liquids - Google Patents

Abstract

Homogeneous electro-viscous liq. contain or consist of Al soaps obtd. by reaction of (un)satd., monomeric, oligomeric and/or polymeric 3-32C polycarboxylic acid(s) with 1 or more COOH gps., or anhydrides and/or semi-esters in which the alcohol component is an (un)branched, 1-12C mono- or poly-alcohol and/or oligomer, with an Al alcoholate in which the alcohol component is an (un)branched 1-18C aliphatic mono- or poly-alcohol. The Al soaps are pref. obtd. by reaction of a 3-18C (12-18C) polycarboxylic acid, anhydride or semi-ester, esp. a 5-18C (12-18C) alkenylsuccinic acid and/or semi-ester, partic. polycarboxylic acids, anhydrides or semi-esters with free OH gps.. The alcohol component of the semi-ester is a 1-6C (2-5C) di-, tri- or tetra-ol or an oligomer. In the Al alcoholates, the valency of the Al is (partly) the same. The electro-viscous liqs. contain (a) 2-50 (10-35) wt.% of the Al soap, in homogeneous soln., (b) 50-98% (65-90%) of a conventional hydraulic base fluid, and (c) 0-10% (0.1-2%) of soluble known hydraulic oil additive.

Description

The invention relates to homogeneous electroviscous liquids (EVF).

Electroviscous liquids have long been known in the form of dispersions of finely divided hydrophilic solids in hydrophobic liquids. The special feature of these liquids is that their flow behavior and thus their viscosity can be changed within wide limits by applying an electric field, so that there are wide-ranging and versatile possible applications. Electroviscous liquids are intended for use in particular in the field of industrial and vehicle hydraulics, e.g. for machine and engine mounting or damping, for positioning workpieces, for vehicle level control, vehicle suspension and damping as well as for torque converters and automatic clutches.

The material composition of the known electroviscous liquids is very different. As a rule, the electroviscous liquids consist of three components, a disperse phase which contains silicates, zeolites, titanates, semiconductors, polysaccharides or organic polymers, an electrically non-conductive hydrophobic liquid as the liquid phase and a dispersant.

DE 35 36 934 A1 describes electroviscous liquids whose disperse phase contains aluminum silicates which have a water content of 1-25% by weight and whose atomic ratio Al / Si on the surface is between 0.15 and 0.80.

US-A-3 047 507 describes the use of solid particles, inter alia, of a size defined from certain aluminum tris-monocarboxylates as active components for electrorheological liquids.

• Neigung zu sehr starker Abrasion
• Ausdampfen von Kristallwasser
• Fehlende Filtrierbarkeit zur Abscheidung von Fremdstoffen
• Vorhandensein von toxisch-/sicherheitsbedenklichen Komponenten
• Unverträglichkeit mit elastomeren Dichtungswerkstoffen.

In all known electro-viscous liquids, however, since they are dispersions, there is the disadvantage that considerable proportions of additional dispersing components are required to reduce the material-related tendency to sedimentation. The suitability of the known products, particularly in long-term use, is therefore unsatisfactory in many cases for use in modern hydraulic units. In particular, conventional dispersions have technical-hydraulic disadvantages, of which only a few are mentioned below:

• Very strong abrasion tendency
• Evaporation of crystal water
• Lack of filterability for the separation of foreign substances
• Presence of toxic / safety-critical components
• Incompatibility with elastomeric sealing materials.

It is also known that many highly polar liquids in the high-voltage field also show certain changes in the flow behavior. However, these effects are weak and cannot be used technically.

The object of the invention is therefore to provide homogeneous electroviscous liquids which meet the technical requirements of a modern industrial hydraulic fluid and which do not have the disadvantages described, but rather have a high electroviscous effect.

According to the invention, this object is achieved by the provision of electroviscous liquids which contain or consist of aluminum soaps,
which by reacting one or more saturated and / or unsaturated monomeric, oligomeric and / or polymeric carboxylic acid (s) with several carboxyl groups and 3 to 32, preferably 3 to 18 and in particular 12 to 18 C atoms, their anhydrides and / or half esters , his or her
Alcohol component (s) are straight or branched, mono- or polyhydric alcohols with 1 to 12, preferably 1 to 6 and in particular 2 to 5 carbon atoms and / or their oligomers,
are produced with one or more aluminum alcoholates, the alcohol component (s) of which are one or more aliphatic, straight or branched, monohydric or polyhydric alcohols having 1 to 18, preferably 2 to 8 and in particular 2 to 5 carbon atoms.

Surprisingly, it was found that a high electrorheological effect is achieved by doping with aluminum. Completely homogeneous products are obtained.

According to the invention, the reaction products of the polycarboxylic acids, anhydrides or half esters with aluminum alcoholates are used as aluminum soaps, in which all or some of the valences of the aluminum are converted. Aluminum soaps are preferably used, which are the reaction products of the polycarboxylic acids, their anhydrides and in particular their half esters, which have one or more free OH groups, with aluminum alcoholates. The aluminum soaps are produced in particular by reacting one or more alkenylsuccinic acids and / or their half esters with 5 to 18 C atoms and preferably 12 to 18 C atoms.

Komponente (a):

2-50 Gew.%, vorzugsweise 5-40 Gew.%, insbesondere 10-35 Gew.% der Aluminiumseife, in homogener Lösung mit

Komponente (b):

50-98 Gew.%, vorzugsweise 60-95 Gew.%, insbesondere 65-90 Gew.%, einer konventionellen Hydraulik-Basisflüssigkeit, und zusätzlich

Komponente (c):

0-10 Gew.%, vorzugsweise 0-5 Gew.%, insbesondere 0,1 bis 2 Gew.%, löslicher, an sich bekannter Hydraulik-Additiven,

jeweils bezogen auf die Gesamtzusammensetzung.The electroviscous liquids according to the invention preferably comprise the following individual components:

Component (a):

2-50% by weight, preferably 5-40% by weight, in particular 10-35% by weight, of the aluminum soap in a homogeneous solution

Component (b):

50-98% by weight, preferably 60-95% by weight, in particular 65-90% by weight, of a conventional hydraulic base fluid, and additionally

Component (c):

0-10% by weight, preferably 0-5% by weight, in particular 0.1 to 2% by weight, of soluble hydraulic additives known per se,

each based on the total composition.

Component (a) consists of oligomeric, complex aluminum soaps based on reaction adducts of polycarboxylic acids or olefin carboxylic acids, their anhydrides, half-esters or oligomers with aluminum alcoholates. Soap formation takes place completely or partially, for example by targeted partial hydrolysis, so that hydroxyl soap structures are formed.

Olefin carboxylic acids are to be understood as carboxylic acids which are formed by reacting unsaturated carboxylic acids with one another or with olefins. Those compounds are used as their oligomers which consist of 2 to 10, preferably 2 to 6, units.

Lower straight and branched alcohols are used as alcohol components of the Al alcoholates, in particular those with C ₁ to C ₆ . The alcohols are released and discharged during the reaction. In the case of reaction with anhydrides, straight-chain or branched alcohols with up to 18 carbon atoms can be used as the alcohol component, which essentially remain in the molecule of the reaction product due to addition.

Straight-chain or branched mono- or polyhydric alcohols are used as alcohol components of the polycarboxylic acid semiesters. The C number is advantageously determined by the selection of the base liquid in order to ensure the solubility of the corresponding reaction products.

Partial ester / aluminum alcoholate adducts based on alkenylsuccinic anhydrides, in particular, are examples of component (a)
N-hexenyl succinic anhydrides, diisobutenyl succinic anhydrides, tetrapropenyl succinic anhydrides, dodecenyl succinic anhydrides and polyisobutenyl succinic anhydrides are given.
Likewise, for example, olefin addition products of itaconic, citraconic and mesaconic acid are also suitable.

Copolymers of unsaturated carboxylic acids, e.g. use maleic, fumaric, acrylic or methacrylic acid. Polyesters bearing carboxyl groups and based on saturated or aromatic dicarboxylic acids such as adipic acid or phthalic acid can also be used.

As Al alcoholates, for example
Aluminum triisopropoxide,
Aluminum-tri-sec.-butoxides or complex mixed alcohols and partial chelates, such as the commercial products from Condea, Hamburg, Dorox D 15, Dorox D 300, Dorox D 310 are used.

Aluminum alcoholates are preferably used, the bonds of which on the aluminum all carry alcoholate groups. However, those can also be used in which one or two bonds of aluminum are occupied by hydroxyl groups.

Component (b) includes hydraulic media such as
conventional mineral oil selective raffinates, hydrocrackates, hydrogenates, poly-alpha-olefins or synthetic esters.

The viscosity position of these liquids is selected according to the requirements for the end product.

• Spindelölraffinat 6/20, Fa. DEA, Hamburg

  Kin. Vis. bei 40 °C:

  4,2 mm²/s

  Dichte bei 15 °C:

  840 kg/m

• Solventraffinat SN 45, Fa. DEA, Hamburg

  Kin. Vis. bei 40 °C:

  6,5 mm²/s

  Dichte bei 15 °C:

  842 kg/m³

• Hydrocrackat VHVI-leicht, Fa. DEA, Hamburg

  Kin. Vis. bei 40 °C:

  30,4 mm²/s

  Dichte bei 15 °C:

  854 kg/m³

• Hitec 162, PAO, Fa. Ethyl, St. Louis

  Kin. Vis. bei 40 °C:

  5.0 mm²/s

  Dichte bei 15 °C:

  800 kg/m³

• Priolube 3958, Fa. Unichema, Gouda

  Kin. Vis. bei 40 °C:

  10,5 mm²/s

  Dichte bei 15 °C:

  921 kg/m³

Examples of component (b) are:

• Spindelölraffinat 6/20, DEA, Hamburg

  Kin. Vis. at 40 ° C:

  4.2 mm ² / s

  Density at 15 ° C:

  840 kg / m

• Solvent raffinate SN 45, DEA, Hamburg

  Kin. Vis. at 40 ° C:

  6.5 mm ² / s

  Density at 15 ° C:

  842 kg / m ³

• Hydrocrackate VHVI-light, from DEA, Hamburg

  Kin. Vis. at 40 ° C:

  30.4 mm ² / s

  Density at 15 ° C:

  854 kg / m ³

• Hitec 162, PAO, Ethyl, St. Louis

  Kin. Vis. at 40 ° C:

  5.0 mm ² / s

  Density at 15 ° C:

  800 kg / m ³

• Priolube 3958, Unichema, Gouda

  Kin. Vis. at 40 ° C:

  10.5 mm ² / s

  Density at 15 ° C:

  921 kg / m ³

Component (c) comprises conventional hydraulic additives for optimizing the hydraulic product properties, such as the
Wear protection, aging stability, friction behavior, tendency to foam, corrosion protection or cold behavior.

• Additin RC 3212, Fa. Rhein-Chemie, Mannheim 2-Ethylhexyl-Zn-dithiophosphat
• Irganox L 107, Fa. Ciba-geigy, Basel 2,6-Di-tert.-butyl-phenol
• Viscoplex 1-300, Fa. Röhm, Darmstadt Polymethacrylat, 70%ig in Neutralraffinat.

Examples of component (c) are:

• Additin RC 3212, Rhein-Chemie, Mannheim, 2-ethylhexyl-Zn-dithiophosphate
• Irganox L 107, from Ciba-geigy, Basel 2,6-di-tert-butyl-phenol
• Viscoplex 1-300, Röhm, Darmstadt polymethacrylate, 70% in neutral raffinate.

In a preferred method of producing the EVF, the olefin carboxylic acid half ester is initially introduced in dilute form and the Al carrier component is added with the rejection of moisture. Component (b) is used to set the nominal viscosity after completion of the chemical reaction, and additive is added with component (c) according to the respective requirements.

The liquids produced in this way show a strongly increasing viscosity increase with a strengthening of the field in the voltage field from approx. 500 V / mm field strength. The optimum responsiveness is in the range of 3-8 kV / mm field strength with an aluminum content of preferably 0.1 to 0.5%. The initial viscosity of the EVF can range from 15 to 6000 mPa s at 40 ° C.

Embodiments

In the exemplary embodiments described below, Example 1 is based on an olefin carboxylic acid not reacted with Al alcoholate. It was not effective.

Example 2 is based on a reaction with Li alcoholate. The electro-rheological effect of the product is extremely low and can only be demonstrated in a static test.

Examples 3 to 5 describe reaction products according to the invention. The corresponding electrorheological measurement results are shown in Figures 1-5.

Example 1 (comparison)

100 g of an alkenylsuccinic acid half ester with the following characteristics Density at 15 ° C 985 kg / m ³ Kin. Vis. at 40 ° C 1750 mm ² / s Viscosity at 100 ° C 31 mm ² / s Flash point PM 175 ° C Mineral oil content 37 % By weight Acid number (SZ) 144 mgKOH / g Hydroxyl number (OHZ) 43 mgKOH / g were diluted with 100 g of a naphthenic mineral oil cut.

• 0,1 % eines kommerziellen Demulgators und
• 0,1 % eines kommerziellen Entschäumers

zugesetzt.The mix continued

• 0.1% of a commercial demulsifier and
• 0.1% of a commercial defoamer

added.

The final mix had one
Viscosity of 39 mm ² / s at 40 ° C and an acid number of 72 mgKOH / g
In the high-voltage rotary rheometer, this mixture showed no detectable increase in shear stress up to 8 KV / mm field strength with a shear stress of D = 1/100.

Example 2 (comparison)

100 g of the final mixture according to Comparative Example 1 were with exclusion of moisture over a period of 30 min. with intensive stirring, a dispersion of 1 g of lithium sec-butoxide in 5 ml of light oil was added. The temperature was slow over 60 min. brought to 80 ° C and at this temperature for a further 90 min. held.

After cooling, the reaction product was diluted with 100 ml of petroleum ether and washed 4 times with 60 ml of H ₂ O.

• Viskosität von 160 mm²/s bei 20 °C und einem
• Lithiumgehalt von 0,11 % erhalten.

Im Hochspannungs-Rotationsrheometer zeigte diese Mischung bis 8 KV/mm Feldstärke bei einer Scherbeanspruchung von D = 1/100 keinen nachweisbaren Anstieg der Schubspannung.After filtration and evaporation of the petroleum ether, 73 g of a product with a

• Viscosity of 160 mm ² / s at 20 ° C and one
• Lithium content of 0.11% obtained.

In the high-voltage rotary rheometer, this mixture showed no detectable increase in shear stress up to 8 KV / mm field strength with a shear stress of D = 1/100.

Example 3

Procedure as in Example 2, but with a solution of
2.5 g of aluminum sec-butoxide reacted in 10 ml of light oil.

• Viskosität von 330 mm²/s bei 40 °C und einen
• Aluminiumgehalt von 0,24 %.

Das Produkt zeigte einen starken elektroviskosen Effekt, dargestellt anhand der Ergebnisse in Figur 1 und 2.The end product had one

• Viscosity of 330 mm ² / s at 40 ° C and a
• Aluminum content of 0.24%.

The product showed a strong electroviscous effect, shown on the basis of the results in FIGS. 1 and 2.

Example 4

Procedure as in Example 2, but with a solution of
1.7 aluminum sec-butylate implemented in 8 ml of light oil.

• Viskosität von 826 mm²/s bei 40 °C und einen
• Aluminiumgehalt von 0,17 %

Das Produkt zeigte einen starken elektroviskosen Effekt, dargestellt anhand der Ergebnisse in Figur 3.The end product had one

• Viscosity of 826 mm ² / s at 40 ° C and one
• Aluminum content of 0.17%

The product showed a strong electroviscous effect, shown on the basis of the results in FIG. 3.

Example 5

Procedure as in Example 2, but with a solution of
1,2 aluminum sec-butoxide reacted in 5 ml of light oil.

• Viskosität von 800 mm²/s bei 20 °C und einen
• Aluminiumgehalt von 0,14 %.

Das Produkt zeigt einen starken elektroviskosen Effekt, dargestellt anhand der Ergebnisse in Figur 4 und 5.The end product had one

• Viscosity of 800 mm ² / s at 20 ° C and a
• Aluminum content of 0.14%.

The product shows a strong electroviscous effect, shown on the basis of the results in FIGS. 4 and 5.

Claims (8)

1. Use of compositions of fluids comprising aluminium carboxylates as electro-viscous fluids characterized in that these are homogeneous electro-viscous fluids and contain aluminium salts of organic acids as electro-viscous active component, whereby the aluminium salts of organic acids are produced by reacting one or more saturated and / or unsaturated monomeric, oligomeric and / or polymeric C₃ to C₃₂ polycarboxylic acid(s) having one or more carboxylic groups, the anhydrides and / or semi-esters thereof, the alcohol component(s) thereof are straight or branched, monohydric or polyhydric C₁ to C₁₂ alcohols and / or the oligomers thereof with one or more aluminium alcoholates, the alcohol components thereof are one or more aliphatic straight or branched, mono- or polyhydric C₁ to C₁₈ alcohols.
2. Use according to claim 1 characterized in that the compositions of fluids contain aluminium salts of organic acids which are produced by reacting one or more polycarboxylic acids, anhydrides or semi-esters with 3 to 18 carbon atoms, particularly with 12 to 18 carbon atoms.
3. Use according to claim 1 or 2 characterized in that the compositions of fluids contain aluminium salts of organic acids which are produced by reacting one or more alkenyl succinic acids and or semi-esters thereof with 5 to 18 carbon atoms, particularly with 12 to 18 carbon atoms.
4. Use according to any of the preceding claims characterized in that the compositions of fluids contain aluminium salts of organic acids which are products obtained by reacting polycarboxylic acids, anhydrides or semi-esters with aluminium alcoholates, all or part of the valences of the aluminium having been reacted.
5. Use according to any of the preceding claims characterized in that the compositions of fluids contain aluminium salts of organic acids, which are products obtained by reacting polycarboxylic acids, the anhydrides and particularly the semi-esters thereof, which comprise one ore more free OH groups with aluminium alcoholates.
6. Use according to any of the preceding claims characterized in that the compositions of fluids contain aluminium salts of organic acids, which are a product obtained by reacting semi-esters, the alcohol component(s) thereof are di- to tetrahydric alcohols with 1 to 6 carbon atoms, particularly 2 to 5 carbon atoms and the oligomers thereof.
7. Use according to any of the preceding claims characterized in that the composition of the fluids consists of:

   (a) 2 to 50 wt.-% of the aluminium salts of organic acids in homogeneous solution with

   (b) 50 to 98 wt.-% of a conventional hydraulic base fluid, and additionally

   (c) 0 to 10 wt.-% soluble hydraulic oil additives known per se,

   each referring to the total composition.
8. Use according to any of the claims 1 to 6 characterized in that the composition of the fluids consists of:

   (a) 5 to 40 wt.-% of the aluminium salts of organic acids in homogeneous solution with

   (b) 60 to 95 wt.-% of a conventional hydraulic base fluid and additionally

   (c) 0 to 5 wt.-% of soluble hydraulic oil additives known per se,

   each referring to the total composition.

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