EP4286497A1 - New low viscosity functional fluids - Google Patents

Abstract

The present invention describes low-viscosity functional fluids, especially brake fluids based on organic silicon compounds and alkoxyglycols.

Description

The present invention describes low-viscosity functional fluids, especially brake fluids based on organic silicon compounds and alkoxyglycols.

These brake fluids have a high dry and wet boiling point and a low low-temperature viscosity, which makes them particularly suitable for modern brake systems.

Typical functional liquids contain mixtures of alkoxyglycols and their boric acid esters. These are widely used as brake fluids. Increasing demands on brake fluids require ever higher dry and wet boiling points while at the same time reducing viscosity.

The current requirement according to DOT 5.1 calls for dry and wet boiling points of more than 260 and 180 °C, respectively, as well as a kinematic viscosity at -40 °C of less than 900 mm ² /s.

At least one silicon ester-based brake fluid is freely available on the market, which has a silicon content of 8% by weight, i.e. it is essentially a pure reaction product of an organic silicon compound with alkoxyglycols.

According to the product data sheet, this product has very high dry and wet boiling points of 320 and 270 °C, respectively, but a high kinematic viscosity at -40 °C of 1300 mm ² /s, which does not meet the requirement of DOT 5.1.

Such silicone ester-based liquids and their use as hydraulic oils are known DE-OS 2147853 . In the examples, the silicone esters are used either in pure form or in a mixture with boric acid esters and alkoxyglycols. Mixtures of silicone esters with alkoxyglycols are not described.

The object of the present invention was to develop brake fluids that retain the advantage of high dry and wet boiling points of silicon ester-based compounds and reduce the viscosity at least to the low level required by DOT 5.1, preferably to a kinematic viscosity at -40 ° C of not more than 750 cSt (mm ² /s), as required in ISO 4925, Class 6.

• (A) mindestens einen Alkoxyglykol gemäß Formel (I)
  
           H₃C-O-[-CH₂-CH₂-O-]_n-H
  
  worin
  • n eine ganze Zahl von 2 bis 5 ist und
  • für mindestens 30 Gew% aller Komponenten der Formel (I) n = 3 gilt,
• (B) mindestens einen Alkoxyglykol gemäß Formel (II,)
  
           R¹-O-[-CH₂-CH₂-O-]_m-H
  
  worin
  • R¹ C₂- bis C₄-Alkyl,
  • m eine ganze Zahl von 2 bis 6 ist und
  • für mindestens 65 Gew% aller Komponenten der Formel (I) m = 3 gilt,
• (C) mindestens ein Glykol gemäß Formel (III)
  
           H-O-[-CH₂-CH₂-O-]_k-H
  
  worin
  • k eine ganze Zahl von mindestens 2 ist und
  • mindestens 80 Gew% aller Komponenten der Formel (III) n = 2 oder 3 gilt,
• (D) mindestens ein Additiv, ausgewählt aus der Gruppe bestehend aus Korrosionsinhibitoren, Aminen, Stabilisatoren, Entschäumern und Schmiermitteln,
• (E) mindestens eine organische Siliziumverbindung der Formel (IV)
  
           R¹¹ _x-Si(-[-O-CH₂-CH₂-]_z-O-R¹²)_4-x
  
  worin
  • x eine positive ganze Zahl 1, 2 oder 3, bevorzugt 2
  • z eine ganze Zahl von 2 bis 4 ist
  • R¹¹ C₁- bis C₄-Alkyl, besonders Methyl oder Ethyl, besonders bevorzugt Methyl und
  • R¹² C₁- bis C₄-Alkyl, besonders Methyl oder n-Butyl, besonders bevorzugt Methyl ist,
  • worin der Anteil an
• (E) 40 bis 55 Gew% beträgt, bevorzugt 43 bis 55, besonders bevorzugt 45 bis 53, ganz besonders bevorzugt 47 bis 52 Gew%,
• (A) 24 bis 45 Gew%,
• (B) 5 bis 20, bevorzugt 7 bis 15 Gew%,
• (C) 0 bis 10 Gew%, bevorzugt 0 bis 5 Gew%,
• (D) mehr als 0 bis 5 Gew%
  • beträgt,
  • mit der Maßgabe, daß die Summe aller Komponenten (A) bis (E) immer 100 Gew% ergibt, worin in den Komponenten (A) bis (C) und (E)
    • die Summe aller Alkoxyglykole bzw. Glykole mit n, m, k und z = 2 beträgt mehr als 0 (Null) und nicht mehr als 10%
    • die Summe aller Alkoxyglykole bzw. Glykole mit n, m, k und z = 3 mindestens 60%, und
    • die Summe aller Alkoxyglykole bzw. Glykole mit n, m, k und z = 4 mehr als 0% bis 20% ausmachen und
    • der Anteil an Borsäureestern mit Alkoxyglykole bzw. Glykole nicht mehr als 3 Gew% beträgt.

This task was solved by containing functional liquids with a viscosity at -40 ° C according to FMVSS 116 of not more than 750 cSt

• (A) at least one alkoxyglycol according to formula (I)
  
  H ₃ CO-[-CH ₂ -CH ₂ -O-] _n -H
  
  wherein
  • n is an integer from 2 to 5 and
  • for at least 30% by weight of all components of the formula (I) n = 3 applies,
• (B) at least one alkoxyglycol according to formula (II,)
  
  R ¹ -O-[-CH ₂ -CH ₂ -O-] _m -H
  
  wherein
  • R ¹ C ₂ - to C ₄ alkyl,
  • m is an integer from 2 to 6 and
  • for at least 65% by weight of all components of the formula (I) m = 3 applies,
• (C) at least one glycol according to formula (III)
  
  HO-[-CH ₂ -CH ₂ -O-] _k -H
  
  wherein
  • k is an integer of at least 2 and
  • at least 80% by weight of all components of the formula (III) n = 2 or 3,
• (D) at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants,
• (E) at least one organic silicon compound of the formula (IV)
  
  R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x
  
  wherein
  • x is a positive integer 1, 2 or 3, preferably 2
  • z is an integer from 2 to 4
  • R ¹¹ C ₁ - to C ₄ alkyl, especially methyl or ethyl, particularly preferably methyl and
  • R ¹² is C ₁ - to C ₄ alkyl, especially methyl or n-butyl, particularly preferably methyl,
  • in which the share of
• (E) is 40 to 55% by weight, preferably 43 to 55, particularly preferably 45 to 53, very particularly preferably 47 to 52% by weight,
• (A) 24 to 45% by weight,
• (B) 5 to 20, preferably 7 to 15% by weight,
• (C) 0 to 10% by weight, preferably 0 to 5% by weight,
• (D) more than 0 to 5% by weight
  • amounts,
  • with the proviso that the sum of all components (A) to (E) always amounts to 100% by weight, where in components (A) to (C) and (E)
    • the sum of all alkoxyglycols or glycols with n, m, k and z = 2 is more than 0 (zero) and not more than 10%
    • the sum of all alkoxyglycols or glycols with n, m, k and z = 3 at least 60%, and
    • the sum of all alkoxyglycols or glycols with n, m, k and z = 4 make up more than 0% to 20% and
    • the proportion of boric acid esters with alkoxyglycols or glycols is not more than 3% by weight.

While silicone ester-based compounds have a high dry and wet boiling point but too high a viscosity, low molecular weight glycols or alkoxyglycols have a low viscosity but also low boiling points. However, the higher the degree of alkoxylation of the alkoxyglycols, the more their boiling point increases, but at the same time the advantage of low viscosity is lost.

The functional liquids according to the invention nevertheless have a low viscosity with high values for dry and wet boiling points, with which the above requirements are met. These properties are achieved through a balanced and coordinated selection of components that have high dry and wet boiling points and those that have a low viscosity. In particular, the degree of alkoxylation of the glycols or Alkoxyglycols are chosen so that these compounds meet a compromise between a sufficiently high boiling point and a sufficiently low viscosity.

Glycols and alkoxyglycols based on triethylene glycol have been found to offer this compromise between low viscosity and high dry or wet boiling point, therefore these species represent the largest part in the functional fluids with at least 60%.

Although glycols and alkoxyglycols based on diethylene glycol have a low viscosity, they lower the required boiling point so that their proportion is no more than 10%.

Conversely, glycols and alkoxyglycols based on tetraethylene glycol have a high boiling point, but at the same time a relatively high viscosity, so their proportion does not exceed 20%.

Glycols have a relatively high viscosity due to their two free hydroxy groups, so that their proportion in the functional liquid should not exceed 10% by weight, preferably 5% by weight.

The percentages refer to the mol% of the respective oligomers mentioned in components (A), (B), (C) and (E), taking into account that the alkoxyglycols in component (E) (4-x) -compartment are installed.

These components are described in detail as follows:
Component (A) is at least one alkoxyglycol of the formula (I)

H ₃ CO-[-CH ₂ -CH ₂ -O-] _n -H

wherein
n is an integer from 2 to 5, preferably 2 to 4 and particularly preferably 3 or 4 and n = 3 applies to at least 30% by weight of all components of the formula (I).

These can be one to four, preferably one to three, particularly preferably one or two and very particularly preferably one alkoxyglycol.

Typical components (A) are diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether and pentaethylene glycol monomethyl ether.

Preferred among these are diethylene glycol monomethyl ether, triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, particularly preferably triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, very particularly preferably triethylene glycol monomethyl ether.

Typically, component (A) is a mixture which consists mainly of triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether and in which higher and lower alkylene glycol monomethyl ether preferably each make up less than 10% by weight, particularly preferably make up less than 10% by weight in total . Very particularly preferably, component (A) is mainly triethylene glycol monomethyl ether, in which higher and lower alkylene glycol monomethyl ethers preferably each make up less than 20% by weight, particularly preferably less than 10% by weight in total.

The proportion of triethylene glycol monomethyl ether in component (A) is at least 30% by weight, preferably at least 40, particularly preferably at least 50 and very particularly preferably at least 60% by weight.

In a preferred embodiment, the proportion of triethylene glycol monomethyl ether in component (A) is at least 75% by weight, particularly preferably at least 85, very particularly preferably at least 90, in particular at least 95% by weight.

• R¹ C₂- bis C₄-Alkyl, bevorzugt Ethyl, n-Propyl, n-Butyl, besonders bevorzugt Ethyl und n-Butyl und ganz besonders bevorzugt n-Butyl,
• m eine ganze Zahl von 2 bis 6, bevorzugt 2 bis 5, besonders bevorzugt 2 bis 4 und ganz besonders bevorzugt 3 oder 4 ist und
• für mindestens 65 Gew% aller Komponenten der Formel (I) m = 3 gilt,
• Dies können ein bis fünf, bevorzugt ein bis vier, besonders bevorzugt ein bis drei, ganz besonders bevorzugt ein oder zwei und insbesondere ein Alkoxyglykol sein.

Component (B) is at least one alkoxyglycol of the formula (II)

R ¹ -O-[-CH ₂ -CH ₂ -O-] _m -H

wherein

• R ¹ C ₂ - to C ₄ alkyl, preferably ethyl, n-propyl, n-butyl, particularly preferably ethyl and n-butyl and very particularly preferably n-butyl,
• m is an integer from 2 to 6, preferably 2 to 5, particularly preferably 2 to 4 and very particularly preferably 3 or 4 and
• for at least 65% by weight of all components of the formula (I) m = 3 applies,
• These can be one to five, preferably one to four, particularly preferably one to three, very particularly preferably one or two and in particular one alkoxyglycol.

Preferred compounds (B) are the corresponding oligoethylene glycol monoethyl ether, oligoethylene glycol mono n-propyl ether and oligoethylene glycol mono n-butyl ether, particularly preferably oligoethylene glycol monoethyl ether and oligoethylene glycol mono n-butyl ether and very particularly preferably oligoethylene glycol mono n-butyl ether.

The oligoethylene glycol monoalkyl ethers are preferably diethylene glycol monoalkyl ethers, triethylene glycol monoalkyl ethers, tetraethylene glycol monoalkyl ethers and pentaethylene glycol monoalkyl ethers, particularly preferably diethylene glycol monoalkyl ethers, triethylene glycol monoalkyl ethers and tetraethylene glycol monoalkyl ethers, most preferably triethylene glycol monoalkyl ethers and tetraethylene glycol col monoalkyl ether and in particular triethylene glycol monoalkyl ether.

In a preferred embodiment, component (B) is a mixture which consists mainly of triethylene glycol mono n-butyl ether and tetraethylene glycol mono n-butyl ether and in which higher and lower alkylene glycol monoalkyl ethers preferably each make up less than 10% by weight, particularly preferably totaling less than 10% by weight. Most preferably, component (B) is mainly triethylene glycol mono n-butyl ether, in which higher and lower alkylene glycol monoalkyl ethers preferably each make up less than 20% by weight, particularly preferably less than 10% by weight in total.

The proportion of triethylene glycol monoalkyl ether in component (B) is at least 65% by weight, preferably at least 70, particularly preferably at least 75 and very particularly preferably at least 80% by weight.

• k eine ganze Zahl von mindestens 2 ist und
• mindestens 80 Gew% aller Komponenten der Formel (III) n = 2 oder 3 gilt.

Component (C) is at least one glycol, for example one to four, preferably one to three, particularly preferably one or two and very particularly preferably a compound according to formula (III)

HO-[-CH ₂ -CH ₂ -O-] _k -H

wherein

• k is an integer of at least 2 and
• at least 80% by weight of all components of the formula (III) n = 2 or 3 applies.

Examples of such compounds are diethylene glycol, triethylene glycol, tetraethylene glycol and pentaethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol are preferred, diethylene glycol and triethylene glycol are particularly preferred.

Preferably at least 80% by weight of all components (C) are diethylene glycol and triethylene glycol, particularly preferably at least 85, very particularly preferably at least 90 and in particular at least 95% by weight. In a preferred embodiment, component (C) contains at least 60% by weight of diethylene glycol, preferably at least 75%, very particularly preferably at least 85% and in particular at least 90% by weight.

In addition, the brake fluids according to the invention contain at least one additive as component (D), selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants.

Component (D), which may be present in the functional fluid composition, is an additive package, which preferably comprises one or more additives with a corrosion-inhibiting effect. This is preferably at least one additive with a corrosion-inhibiting effect selected from alkylamine ethoxylates.

The alkylamine residue in the alkylamine ethoxylates mentioned can be a secondary or preferably a primary aliphatic monoamine which can be ethoxylated. Secondary or preferably primary aliphatic monoamines are usually used, but polyamines with at least one secondary and/or primary amino group that can be ethoxylated can also be used. The alkyl radicals on the nitrogen atom normally include saturated linear or branched alkyl radicals, but unsaturated linear or branched alkyl radicals or saturated or unsaturated cycloalkyl radicals may also be included in the term "alky radical".

In a preferred embodiment, the alkylamine ethoxylates comprise at least one linear or branched C ₃ to C ₂₀ alkyl chain, preferably at least one linear or branched C ₆ to C ₁₃ alkyl chain, particularly preferably at least one linear or branched C ₇ to C ₁₂ alkyl chain. Alkyl chain -Chain, most preferably at least one linear or branched C ₈ to C ₁₀ alkyl chain, particularly preferably a linear C ₈ alkyl chain. Preferably means the term “alkyl chain” here means saturated and non-cyclic hydrocarbon radicals, particularly preferably linear unbranched alkyl groups. The alkylamine ethoxylates may also comprise mixtures of such alkyl chains, for example a mixture of homologous alkyl radicals, depending on the specific technical or natural origin of the alkylamines used.

Suitable examples of individual alkylamine molecules that are capable of ethoxylation and are also suitable as surfactants for the present invention are n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-pentylamine, tert -Pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine, n-nonylamine, n-decylamine, 2-propylheptylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, isotridecylamine, n-tetradecylamine, n -Pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-nonadecylamine, n-eicosylamine, di-(n-hexyl)amine, di-(n-heptyl)amine, di-(n-octyl)amine, Di-(2-ethylhexyl)amine, di-(n-nonyl)amine, di-(n-decyl)amine, di-(2-propylheptyl)amine, di-(n-undecyl)amine, di-(n- dodecyl)amine, di-(n-tridecyl)amine, di-(isotridecyl)amine, di-(n-tetradecyl)amine, di-(n-pentadecyl)amine, di-(n-hexadecyl)amine, di-( n-heptadecyl)amine, di-(n-octadecyl)-amine, di-(n-nonadecyl)amine, di-(n-eicosyl)amine, n-hexylmethylamine, n-heptylmethylamine, n-octylmethylamine, (2-ethylhexyl )methylamine, n-nonylmethylamine, n-decylmethylamine, (2-propylheptyl)methylamine, n-undecylmethylamine, n-dodecylmethylamine, n-tridecylmethylamine, isotridecylmethylamine, n-tetradecylmethylamine, n-pentadecylmethylamine, n-hexadecylmethylamine, n- Heptadecylmethylamine, n- Octadecylmethylamine, n-nonadecylmethylamine and n-eicosylmethylamine.

Such alkyl radicals can come entirely from petrochemical production, for example technical C ₈ -C ₁₅ alkyl mixtures, 2-ethylhexyl or 2-propylheptyl, or can be based entirely or partially on renewable raw materials, for example fatty amines such as stearyl, as the basis for the alkylamine ethoxylates can be amines, Oleylamines or tallow amines can be used.

The degree of ethoxylation is typically 1 to 35 ethylene oxide ("EO") units per alkylamine molecule, ie the at least one alkylamine ethoxylate comprises 1 to 35 EO units, preferably 1.5 to 15 EO units, more preferably from 1.8 to 9 EO units, most preferably 2 to 6 EO units. The stated degree of ethoxylation is a statistical value, ie the alkylamine ethoxylates are normally to be viewed as mixtures of species (homologs) with different numbers of EO units. In a particularly preferred embodiment of the present invention, the at least one alkylamine ethoxylate comprises at least one linear C ₃ to C ₂₀ alkyl chain and 1 to 35 EO units; particularly preferably, the at least one alkylamine ethoxylate comprises at least one linear C ₆ - to C ₁₃ -alkyl chain and 1.5 to 15 EO units; very particularly preferably, the at least one alkylamine ethoxylate comprises at least one linear C ₇ to C ₁₁ alkyl chain and 1.8 to 9 EO units; in particular, the at least one alkylamine ethoxylate comprises at least one linear C ₈ to C ₁₀ alkyl chain and 2 to 6 EO units.

Such alkylamine ethoxylates can be primary amines with one oxyethylene chain of the general formula Alkyl-NH-(CH ₂ CH ₂ O) _m -H or primary amines with two oxyethylene chains of the general formula Alkyl-N[(CH ₂ CH ₂ O) _p H][ ( CH ₂ CH ₂ O) _q -H] or secondary amines of the general formula (alkyl) ₂ N-(CH ₂ CH ₂ O) _m H or mixtures of such primary amines with one oxyethylene chain and such primary amines with two oxyethylene chains or mixtures of such primary ones and secondary amines, where m and (p + q) are the total degrees of ethoxylation, respectively. "Alkyl" in the above formulas normally means _C3 to _C20 alkyl, preferably _C6 to _C13 alkyl, more preferably _C7 to _C12 alkyl, most preferably _C8 to _C10 alkyl , as defined above. Other alkylamine species may also be present in smaller amounts, particularly at low total ethoxylation levels below 2.

A typical suitable alkylamine ethoxylate is octylamine (caprylamine) with 2 EO units, which is commercially available.

The alkylamine ethoxylates mentioned can be prepared by conventional processes, such as the reaction of the alkylamine with ethylene oxide under catalysis by alkali metal hydroxides or under catalysis by double metal cyanides, as are known to those skilled in the art. The alkylamine ethoxylates have partly corrosion-inhibiting properties and partly solvent properties for the functional fluid composition or brake fluid according to the present invention.

In addition to the alkylamine ethoxylates, component (D) of the present functional liquid composition can comprise at least one further additive with a corrosion-inhibiting effect.

Common additives with corrosion-inhibiting properties include fatty acids such as lauric, palmitic, stearic or oleic acid; Esters of phosphorus or phosphoric acid with aliphatic alcohols; phosphites such as ethyl phosphate, dimethyl phosphate, isopropyl phosphate, n-butyl phosphate, triphenyl phosphite and diisopropyl phosphite; Reaction products of phosphorus pentoxide with alkoxyglycols as described above as components (A) or (B), heterocyclic nitrogen-containing organic compounds such as benzotriazole, tolutriazole, 1,2,4-triazole, benzoimidazole, purine, adenine and derivatives of such heterocyclic organic compounds; Alkylamines such as mono- and di-(C ₄ - to C ₂₀ -alkyl)amines, for example n-butylamine, n-hexylamine, n-octylamine, 2-ethylhexylamine, isononylamine, n-decylamine, n-dodecylamine, oleylamine, di-n-propylamine, diisopropylamine, di-ni-butylamine, di-n-amylamine, cyclohexylamine and salts of such alkylamines; Alkanolamines such as mono-, di- and trimethanolamine, mono-, di- and triethanolamine, mono-, di- and tri-n-propanolamine and mono-, di- and triisopropanolamine. Of course, mixtures of the above-mentioned additives with a corrosion-inhibiting effect can also be used.

In addition to the alkylamine ethoxylates and, if applicable, the additives with a corrosion-inhibiting effect, other common additives can be included in the additive package of component (D), for example stabilizers such as pH stabilizers, antioxidants such as phenothiazine and phenolic compounds, for example hydroxyanisole and bisphenol A, defoamers and dyes.

In a preferred embodiment, component (D) comprises at least one alkoxylate of ricinoleic acid, castor oil or any other ricinoleic acid ester, preferably ricinoleic acid or castor oil and most preferably castor oil. This castor oil in the sense of the present description is an at least partially and preferably completely esterified acylglycerol, where at least one, preferably at least two of the acyl groups are ricinoleic acid or isoricinoleic acid, preferably ricinoleic acid.

For example, the mixture of fatty acids preferably comprises a mixture of two molecules of ricinoleic acid with a fatty acid that does not carry a hydroxyl group, preferably selected from the group consisting of oleic acid, linoleic acid, palmitic acid and stearic acid.

In a preferred embodiment, the castor oil has an OH number of 160 to 173 mg KOH/g. The alkoxylate of ricinoleic acid, castor oil or any other ricinoleic acid ester is preferably prepared by reacting a saturated or unsaturated hydroxy-substituted C ₈ to C ₂₂ fatty acid or an ester thereof, in particular by reacting ricinoleic acid, castor oil or any other ricinoleic acid ester with at least one alkylene oxide. The alkylene oxide can be propylene oxide, butylene oxide, styrene oxide or preferably ethylene oxide. Mixtures of such alkylene oxides that result in random or block structures of alkylene oxide units can also be used.

In detail, the structure of the alkoxylate preferably comprises a saturated or unsaturated C ₈ to C ₂₂ fatty monocarboxylic acid or at least one saturated or unsaturated C ₈ to C ₂₂ fatty monocarboxylic acid unit in the molecule which is esterified with one or more oxyalkylenes with the free carboxylic acid function, if such a free carboxylic acid function in Molecule is present and carries a hydroxyl group located on the fatty acid side chain of the alkoxylate etherified by one or more oxyalkylene units. Examples of such saturated or unsaturated hydroxyl-substituted C ₈ to C ₂₂ fatty monocarboxylic acids or units thereof, preferably of saturated or unsaturated hydroxyl-substituted C ₁₄ to C ₂₀ fatty monocarboxylic acids or units thereof, as a basis for the alkoxylates are 10-hydroxystearic acid , 12-hydroxystearic acid and especially ricinoleic acid. Such unsaturated hydroxyl-substituted C ₈ to C ₂₂ fatty monocarboxylic acids can be used as free carboxylic acids or as corresponding esters to prepare the alkoxylate. In the case of ricinoleic acid, castor oils as their naturally occurring triglyceride can advantageously be reacted as a transesterification with an alkylene oxide, resulting in the desired ricinoleic acid alkoxylate and glycerin. Any other ester of ricinoleic acid can be used as starting material for the transesterification, for example the corresponding di- or monoglyceride or the corresponding methyl, ethyl, propyl or butyl ester. Depending on the conditions of the alkoxylation reaction with esters of ricinoleic acid, in particular with castor oils, the ester can retain its carboxylic acid esters and especially its glycerol triester function and is alkoxylated one or more times by oxyalkylene units solely on the hydroxy group on the fatty acid side chain.

Said alkoxylate, in particular the alkoxylate of ricinoleic acid, castor oil or any other ricinoleic acid ester, usually comprises 2 to 200, preferably 4 to 100, particularly preferably 6 to 80, most preferably 10 to 50 and especially 20 to 40 alkylene oxide units, which are preferably ethylene oxide units . "Number of alkylene oxide units" means moles of alkylene oxide per mole of the saturated or unsaturated hydroxyl-substituted C ₈ -C ₂₂ fatty monocarboxylic acid or units thereof as the basis for the alkoxylate. Using castor oil, which is the triglyceride of ricinoleic acid, the amount of alkylene oxide used for alkoxylation refers to 3 equivalents of ricinoleic acid or units thereof to be alkoxylated. At higher degrees of alkoxylation, the number of alkylene units is an average as a statistical number, due to a distribution of alkoxylation homologues in the product. There may be two types of hydroxyl groups present in the molecule to be alkoxylated, i.e. one to be esterified (or transesterified) and the other to be etherified, esterification may or may not occur, etherification will always occur.

Processes for alkoxylation, in particular ethoxylation, of carboxylic acids or esters thereof, such as castor oil, are known in the art and therefore need not be described further in this application.

In a preferred embodiment, the functional liquids according to the invention contain at least one compound selected from the group consisting of benzotriazole, tolutriazole, 1,2,4-triazole and benzoimidazole.

In a further preferred embodiment, the functional liquids according to the invention additionally or independently, preferably additionally, contain at least one compound selected from the group consisting of alkylamine ethoxylates with a linear C ₈ to C ₁₀ alkyl chain and 2 to 6 EO units, mono-, di - and triisopropanolamine.

In a further preferred embodiment, the functional liquids according to the invention additionally or independently, preferably additionally contain at least one 10- to 50-fold ethoxylated alkoxylate of ricinoleic acid, castor oil or another ricinoleic acid ester.m

• x eine positive ganze Zahl 1, 2 oder 3, bevorzugt 1 oder 2, besonders bevorzugt 2,
• z eine ganze Zahl von 2 bis 4, bevorzugt 3,
• R¹¹ C₁- bis C₄-Alkyl, besonders Methyl oder Ethyl, besonders bevorzugt Methyl und
• R¹² C₁- bis C₄-Alkyl, besonders Methyl oder n-Butyl, besonders bevorzugt Methyl ist.

Furthermore, the brake fluid according to the present invention also contains at least one organic silicon compound (E) of the formula (IV)

R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x

wherein

• x is a positive integer 1, 2 or 3, preferably 1 or 2, particularly preferably 2,
• z is an integer from 2 to 4, preferably 3,
• R ¹¹ C ₁ - to C ₄ alkyl, especially methyl or ethyl, particularly preferably methyl and
• R ¹² is C ₁ to C ₄ alkyl, especially methyl or n-butyl, particularly preferably methyl.

As stated above, these organic silicon compounds, especially with x = 1 and 2, especially with x = 2, have high wet and dry boiling points. The presence of these compounds (E) in the brake fluid therefore increases these boiling points, but generally also increases their viscosity. Therefore, the aim is to select the proportion of component (E) as high as necessary in order to achieve the desired boiling points, but on the other hand the components (A) to (C) and especially (A) and (B) in type and quantity to be chosen so that they reduce the high viscosity of the components (E) but at the same time have sufficiently high wet and dry boiling points to meet the desired target values.

For this purpose, the brake fluids according to the invention contain at least one organic silicon compound (E), preferably one to four, particularly preferably one to three, very particularly preferably one or two and in particular one.

In the compounds (E), the radicals R ¹¹ can be C ₁ to C ₄ alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or ethyl and very particularly preferably methyl. The x radicals R ¹¹ can be independently the same or different, preferably they are the same.

The number x of radicals R ¹¹ is from 1 to 3, preferably 1 or 2 and particularly preferably 2.

The substructures H-[-O-CH ₂ -CH ₂ -] _z -OR ¹² are alkylene glycol monoalkyl ethers, as also described above for the compounds (A) and (B), preferably R ¹² is C _1- to C ₄ -alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl. The running index z is a positive integer from 2 to 4, preferably 3 or 4 and particularly preferably 3.

In a preferred embodiment, the substructures H-[-O-CH ₂ -CH ₂ -] _z -OR ¹² are selected from the group consisting of diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, diethylene glycol mono n-butyl ether, triethylene glycol mono n-butyl ether and tetraethylene glycol mono n-butyl ether, preferred are triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, triethylene glycol mono n-butyl ether and tetraethylene glycol mono n-butyl ether, particularly preferred are triethylene glycol monomethyl ether and triethylene glycol mono n-butyl ether.

In a preferred embodiment, the substructures H-[-O-CH ₂ -CH ₂ -] _z -OR ¹² are the same alkylene glycol monoalkyl ethers as those used as components (A) and/or (B), particularly preferably the same alkylene glycol monoalkyl ethers as those used as components (A).

• Komponente (E) 40 bis 55 Gew%, bevorzugt 43 bis 55, besonders bevorzugt 45 bis 53, ganz besonders bevorzugt 47 bis 52 Gew%,
• Komponente (A) 24 bis 45 Gew%, bevorzugt 24 bis 40, besonders bevorzugt 24 bis 35, ganz besonders bevorzugt 24 bis 30 Gew%,
• (B) 5 bis 20, bevorzugt 7 bis 15 Gew%,
• (C) 0 bis 10 Gew%, bevorzugt 0 bis 5 Gew%,
• (D) mehr als 0 bis 5 Gew%, bevorzugt 1 bis 4 Gew%,
• mit der Maßgabe, daß die Summe aller Komponenten (A) bis (E) immer 100 Gew% ergibt.

The composition of the functional fluids according to the invention, preferably the brake fluids according to the invention, is as follows:

• Component (E) 40 to 55% by weight, preferably 43 to 55, particularly preferably 45 to 53, very particularly preferably 47 to 52% by weight,
• Component (A) 24 to 45% by weight, preferably 24 to 40, particularly preferably 24 to 35, entirely particularly preferably 24 to 30% by weight,
• (B) 5 to 20, preferably 7 to 15% by weight,
• (C) 0 to 10% by weight, preferably 0 to 5% by weight,
• (D) more than 0 to 5% by weight, preferably 1 to 4% by weight,
• with the proviso that the sum of all components (A) to (E) always amounts to 100% by weight.

• die Summe aller Alkoxyglykole bzw. Glykole mit n, m, k und z = 2 beträgt mehr als 0 (Null) und nicht mehr als 10%
• die Summe aller Alkoxyglykole bzw. Glykole mit n, m, k und z = 3 mindestens 60%, und
• die Summe aller Alkoxyglykole bzw. Glykole mit n, m, k und z = 4 mehr als 0% bis 20% ausmachen.

The proviso applies that in components (A) to (C) and (E)

• the sum of all alkoxyglycols or glycols with n, m, k and z = 2 is more than 0 (zero) and not more than 10%
• the sum of all alkoxyglycols or glycols with n, m, k and z = 3 at least 60%, and
• the sum of all alkoxyglycols or glycols with n, m, k and z = 4 make up more than 0% to 20%.

Furthermore, the proportion of boric acid esters with alkoxyglycols or glycols is not more than 3% by weight, preferably not more than 2.5, particularly preferably not more than 2, very particularly preferably not more than 1.5, in particular not more than 1 and especially no more than 0.5% by weight.

Since components (A), (B) and (C) contain reactive groups that are able to react with the organic silicon compounds (E), the composition of the functional liquids according to the invention can change, for example when exposed to temperatures higher than room temperature and/or storage. Furthermore, such a reaction can be accelerated by the presence of amines as additives (D).

This change in the compositions can, on the one hand, consist in replacing the substructures H-[-O-CH ₂ -CH ₂ -] _z -OR ¹² in component (E) by the alkylene glycol monoalkyl ethers (A) and (B), so that the alkylene glycol monoalkyl ethers (A) and (B) are incorporated into component (E) and free alkylene glycol monoalkyl ether H-[-O-CH ₂ -CH ₂ -] _z -OR ¹² is formed in the composition.

On the other hand, in the presence of the difunctional diglycols (C), polynuclear organic silicon compounds can also form, i.e. compounds that contain more than one silicon atom. For example, dinuclear or trinuclear silicon compounds can form, higher nuclear ones only in small amounts, dinuclear silicon compounds are preferably formed.

The structure of such dinuclear silicon compounds is, for example, as follows:

R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1 -(-O-[-CH ₂ -CH ₂ -O-] _k -)-Si R ¹¹ _x (-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1

where the variables are defined as above. Here x must be at least 2.

For example, the structure of trinuclear silicon compounds is as follows:

R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1 -(-O-[-CH ₂ -CH ₂ -O-] _k -)-Si R ¹¹ _x (-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-2 -(-O-[-CH ₂ -CH ₂ -O-] _k -)-Si R ¹¹ _x ( -[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1

where the variables are defined as above. Here x must be at least 2.

The end point of this change is the composition of a mixture of all components (A) to (E), which is established in thermodynamic equilibrium starting from the initial composition.

Accordingly, a further subject of the present invention is a reaction mixture, obtainable by reacting components (A) to (E) with one another. If diglycols (C) are present, this reaction mixture can also contain polynuclear silicon compounds, for example dinuclear and trinuclear, preferably dinuclear silicon compounds.

The composition of the reaction mixture lies between the initial composition and the composition in thermodynamic equilibrium.

The mixtures according to the invention can be used as functional fluids, for example as hydraulic fluids or in particular as brake fluids.

The brake fluids can be used with particular advantage in vehicles with hydraulic brake systems, for example passenger or commercial vehicles. In particular, these brake fluids are suitable for electronic or automatic brake systems with anti-lock braking systems, which require brake fluids with low viscosities even at low temperatures.

The following examples show the scope and benefits of the compositions according to the invention without reducing them to these examples.

Examples

As an example of a brake fluid, Castrol React SRF Racing was used with an Si content of approximately 8.0% by weight +/- 0.3% by weight (within the measurement accuracy) determined using ICP-OES. Mathematically, this essentially corresponds to a pure silicone ester with triethylene glycol monoalkyl ether as incorporated alkoxyglycol (compound (E) with x = 2, z = 3 and R ¹¹ and R ¹² each C ₁ - to C ₄ -alkyl). This is referred to here as component 1.

• Trockensiedepunkt (ERBP) gemäß ASTM D1120
• Nasssiedepunkt (WERBP) gemäß SAE J1703
• kinematische Viskosität gemäß ASTM D445, wenn nicht anders angegeben bei -40 °C

The following formulations were prepared and their properties were determined as follows:

• Dry Boiling Point (ERBP) according to ASTM D1120
• Wet boiling point (WERBP) according to SAE J1703
• Kinematic viscosity according to ASTM D445 at -40°C unless otherwise stated

example 1

It can be seen that the pure silicone ester has slightly higher values for ERBP and WERBP compared to the pure boric acid ester, but has a significantly higher low-temperature viscosity (entries 1 vs. 4).

When mixed with alkyl glycol ethers, the silicone ester-based mixtures retain and even extend their advantage in ERBP and WERBP, whereby the viscosity can be reduced almost to the level of the boric acid ester-based mixtures (entries 2 vs. 5 and 3 vs. 6 ).

Example 2

A formulation with the following composition (in% by weight) was prepared: Example 1 2 3 V1 V2 V3 V4 V5 V6 V7 Component 1 40 50 55 50 50 50 50 50 50 55 BTG 10 10 10 10 0 10 5 5 15 10 MTG 29.2 24.2 29.2 24.2 34.2 34.2 19.2 0 19.2 23.2 MTeG 15 10 0 2 10 0 20 39.2 10 6 DEG 2 2 2 10 2 2 2 2 2 2 Additive mixture 2 2 2 2 2 2 2 2 2 2 Diisopropanolamine 1 1 1 1 1 1 1 1 1 1 Octyldiethanolamine 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Viscosity at -40 °C [mm ² /s] 661 704 746 987 705 674 837 1064 805 810 ERBP [°C] 274 276 278 265 274 273 281 289 280 280 WERBP [°C] 165 177 171 157 159 160 163 165 159 166 BTG: triethylene glycol mono-n-butyl ether (compound (B), m = 3, R ¹ = n-butyl)
MTG: triethylene glycol monomethyl ether (compound (A), n = 3)
MTeG: tetraethylene glycol monomethyl ether (compound (A), n = 4)
DEG: Diethylene glycol (compound (C), k = 2)

Additive mixture: 2.5% corrosion inhibitor, 2.5% and 10.0% lubricant as described in WO 2015/052234 , composition FFC4, anionic wetting aid 0.25%, aminic antioxidant as heat stabilizer 1.5% dissolved in 83.25% MTG

Claims (15)

Containing functional fluids having a viscosity at -40°C in accordance with FMVSS 116 of not more than 750 cSt (mm ² /s). (A) at least one alkoxyglycol according to formula (I)

H ₃ CO-[-CH ₂ -CH ₂ -O-] _n -H

wherein n is an integer from 2 to 5 and for at least 30% by weight of all components of the formula (I) n = 3 applies, (B) at least one alkoxyglycol according to formula (II,)

R ¹ -O-[-CH ₂ -CH ₂ -O-] _m -H

wherein R ¹ C ₂ - to C ₄ alkyl, m is an integer from 2 to 6 and for at least 65% by weight of all components of the formula (I) m = 3 applies, (C) at least one glycol according to formula (III)

HO-[-CH ₂ -CH ₂ -O-] _k -H

wherein k is an integer of at least 2 and at least 80% by weight of all components of the formula (III) n = 2 or 3, (D) at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants, (E) at least one organic silicon compound of the formula (IV)

R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x

wherein x is a positive integer 1, 2 or 3, preferably 2 z is an integer from 2 to 4 R ¹¹ C ₁ - to C ₄ alkyl, especially methyl or ethyl, particularly preferably methyl and R ¹² is C ₁ - to C ₄ alkyl, especially methyl or n-butyl, particularly preferably methyl, in which the share of (E) is 40 to 55% by weight, preferably 43 to 55, particularly preferably 45 to 53, very particularly preferably 47 to 52% by weight, (A) 24 to 45% by weight, (B) 5 to 20, preferably 7 to 15% by weight, (C) 0 to 10% by weight, preferably 0 to 5% by weight, (D) more than 0 to 5% by weight amounts, with the proviso that the sum of all components (A) to (E) always amounts to 100% by weight, characterized in that in components (A) to (C) and (E) - the sum of all alkoxyglycols or glycols with n, m, k and z = 2 is more than 0 (zero) and not more than 10% - the sum of all alkoxyglycols or glycols with n, m, k and z = 3 at least 60%, and - the sum of all alkoxyglycols or glycols with n, m, k and z = 4 more than 0% to 20%
make out and - the proportion of boric acid esters with alkoxyglycols or glycols is not more than 3% by weight. Composition according to claim 1, characterized in that component (A) consists mainly of triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether. Composition according to claim 1 or 2, characterized in that the proportion of triethylene glycol monomethyl ether in component (A) is at least 75% by weight, especially preferably at least 85, very particularly preferably at least 90, in particular at least 95% by weight. Composition according to one of the preceding claims, characterized in that component (B) is selected from the group consisting of triethylene glycol mono n-butyl ether and tetraethylene glycol mono n-butyl ether. Composition according to one of the preceding claims, characterized in that component (C) is selected from the group consisting of diethylene glycol and triethylene glycol. Composition according to one of the preceding claims, characterized in that component (D) comprises at least one compound selected from the group consisting of alkylamine ethoxylates, alkanolamines, heterocyclic nitrogen-containing organic compounds and alkoxylates of ricinoleic acid, castor oil or any other ricinoleic acid ester. Composition according to one of the preceding claims, characterized in that in component (E) x = 2. Composition according to any one of the preceding claims, characterized in that in component (E) R ¹¹ is methyl. Composition according to one of the preceding claims, characterized in that in component (E) z = 3. Composition according to any one of the preceding claims, characterized in that in component (E) R ¹² is methyl. Composition according to one of the preceding claims, characterized in that the substructures H-[-O-CH ₂ -CH ₂ -] _z -OR ¹² in component (E) are the same alkylene glycol monoalkyl ethers as those used as components ( A) and/or (B) are used, particularly preferably the same alkylene glycol monoalkyl ethers as those used as components (A). Reaction mixture obtainable by reacting components (A) to (E) according to one of the preceding claims with one another. Reaction mixture according to claim 12, containing at least one diglycol (C) and at least one polynuclear silicon compound, for example dinuclear and trinuclear, preferably dinuclear silicon compound. Reaction mixture according to claim 13, characterized in that the polynuclear silicon compound is selected from the group consisting of

R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1 -(-O-[-CH ₂ -CH ₂ -O-] _k -)-Si R ¹¹ _x (-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1

and

R ¹¹ _x -Si(-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1 -(-O-[-CH ₂ -CH ₂ -O-] _k -)-Si R ¹¹ _x (-[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-2 -(-O-[-CH ₂ -CH ₂ -O-] _k -)-Si R ¹¹ _x ( -[-O-CH ₂ -CH ₂ -] _z -OR ¹² ) _4-x-1 ,

wherein the variables are defined as in any one of the preceding claims and x is at least 2. Use of the compositions and reaction mixtures according to one of the preceding claims as a functional fluid, preferably as a hydraulic fluid or brake fluid.