New low-viscosity functional liquids

Abstract

The present invention relates to low-viscosity functional liquids, in particular brake fluids on the basis of organic silicon compounds and alkoxy glycols.

Description

[0001] New low-viscosity functional fluids

[0002] Description

[0003] The present invention describes low-viscosity functional fluids, particularly brake fluids based on organic silicon compounds and alkoxyglycols.

[0004] These brake fluids have a high dry and wet boiling point and a low low-temperature viscosity, which makes them particularly suitable for modern braking systems.

[0005] Typical functional fluids 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 simultaneously reducing viscosity.

[0006] The current requirement according to DOT 5.1 requires 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.

[0007] At least one silicone 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.

[0008] 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 DOT 5.1 requirement.

[0009] Such silicone ester-based fluids and their use as hydraulic oils are known from DE-OS 2147853. In the examples, the silicone esters are used either in pure form or in blends with boric acid esters and alkoxyglycols. Blends of silicone esters with alkoxyglycols are not described.

[0010] Research Disclosure 694049, published on January 17, 2022, describes compositions of silicone esters and alkoxyglycols. Neither the wet or dry boiling points of these compositions nor their viscosity are specified, so the suitability of the compositions as brake fluids cannot be assessed. The object of the present invention was to develop brake fluids that retain the advantage of high dry and wet boiling points of silicone ester-based compounds and reduce the viscosity to at least the low level required by DOT 5.1, preferably to a kinematic viscosity at -40 °C of no more than 750 cSt (mm 2 / s), as required in ISO 4925, Class 6.

[0011] This task was solved by functional fluids with a viscosity at -40 °C according to FMVSS 116 of not more than 750 cSt, containing

[0012] (A) at least one alkoxyglycol according to formula (I)

[0013] H3C-O-[-CH2-CH2-O-] n -H where n is an integer from 2 to 5 and for at least 30 wt% of all components of formula (I) n = 3,

[0014] (B) at least one alkoxyglycol according to formula (II)

[0015] R 1 -O-[-CH2-CH2-O-]mH where

[0016] R 1 C2- to C4-alkyl, m is an integer from 2 to 6 and for at least 65 wt% of all components of formula (II) m = 3,

[0017] (C) optionally at least one glycol according to formula (III)

[0018] HO-[-CH2-CH2-O-]kH where k is an integer of at least 2 and at least 80 wt% of all components of formula (III) k = 2 or 3,

[0019] (D) at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants,

[0020] (E) at least one organic silicon compound of the formula (IV) R 11 x-Si(-[-O-CH2-CH2-]zOR 12 )4-x where x is a positive integer 1, 2 or 3, preferably 2 z is an integer from 2 to 4

[0021] R 11 Ci- to C4-alkyl, especially methyl or ethyl, particularly preferably methyl and R 12 Ci- to C4-alkyl, especially methyl or n-butyl, particularly preferably methyl, wherein the proportion of

[0022] (E) 40 to 55% by weight, preferably 43 to 55, particularly preferably 45 to 53, most particularly preferably 47 to 52% by weight,

[0023] (A) 24 to 45 wt%,

[0024] (B) 5 to 20, preferably 7 to 15 wt%,

[0025] (C) 0 to 10 wt%, preferably 0 to 5 wt%,

[0026] (D) is more than 0 to 5 wt%, with the proviso that the sum of all components (A) to (E) always amounts to 100 wt%, wherein in components (A) to (C) and (E)

[0027] - the sum of all alkoxyglycols or glycols with n, m, k and z = 2 is more than 0 (zero) and not more than 10 mol%

[0028] - the sum of all alkoxyglycols or glycols with n, m, k and z = 3 is at least 60 mol%, and

[0029] - the sum of all alkoxyglycols or glycols with n, m, k and z = 4 amounts to more than 0 mol% to 20 mol% and

[0030] - the proportion of boric acid esters with alkoxyglycols or glycols does not exceed 3% by weight.

[0031] While silicone ester-based compounds have high dry and wet boiling points, but excessively high viscosity, low-molecular-weight glycols or alkoxyglycols exhibit low viscosity but also low boiling points. However, the higher the degree of alkoxylation of the alkoxyglycols, the higher their boiling point increases, but at the same time, the advantage of low viscosity is lost.

[0032] The functional fluids according to the invention exhibit high dry and wet boiling points while still maintaining a low viscosity, thus meeting the above requirements. These properties are achieved through a balanced and coordinated selection of components that exhibit high dry and wet boiling points and those that exhibit low viscosity. In particular, the degree of alkoxylation of the glycols or alkoxyglycols is selected so that these compounds achieve a compromise between a sufficiently high boiling point and a sufficiently low viscosity.

[0033] Glycols and alkoxyglycols based on triethylene glycol have been found to offer this compromise between low viscosity and high dry or wet boiling points, therefore these species represent the largest proportion in functional fluids, at least 60%.

[0034] Glycols and alkoxyglycols based on diethylene glycol have a low viscosity, but lower the required boiling point, so that their proportion does not exceed 10%.

[0035] Conversely, glycols and alkoxyglycols based on tetraethylene glycol have a high boiling point but at the same time a relatively high viscosity, therefore their proportion does not exceed 20%.

[0036] Due to their two free hydroxyl groups, glycols have a relatively high viscosity, so that their proportion in the functional fluid should not exceed 10 wt%, preferably 5 wt%.

[0037] 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) are incorporated (4-x)-fold.

[0038] These components are described in detail as follows:

[0039] Component (A) is at least one alkoxyglycol of formula (I)

[0040] H3C-O-[-CH2-CH2-O-]nH wherein n is an integer from 2 to 5, preferably 2 to 4, and particularly preferably 3 or 4, and for at least 30% by weight of all components of formula (I) n = 3. These can be one to four, preferably one to three, particularly preferably one or two, and most preferably one alkoxyglycol.

[0041] Typical components (A) are diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether and pentaethylene glycol monomethyl ether.

[0042] Preferred among these are diethylene glycol monomethyl ether, triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, particularly preferred are triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, most particularly preferred are triethylene glycol monomethyl ether.

[0043] Typically, component (A) is a mixture consisting mainly of triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, in which higher and lower alkylene glycol monomethyl ethers preferably each make up less than 10 wt%, particularly preferably less than 10 wt% 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 wt%, particularly preferably less than 10 wt% in total.

[0044] The proportion of triethylene glycol monomethyl ether in component (A) is at least 30% by weight, preferably at least 40% by weight, particularly preferably at least 50% by weight and most particularly preferably at least 60% by weight.

[0045] 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% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight.

[0046] Component (B) is at least one alkoxyglycol of formula (II)

[0047] R 1 -O-[-CH2-CH2-O-]mH where

[0048] R 1 C2- to C4-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 (II) m = 3, 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.

[0049] 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.

[0050] The oligoethylene glycol monoalkyl ethers are preferably diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tetraethylene glycol monoalkyl ether and pentaethylene glycol monoalkyl ether, particularly preferably diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether and tetraethylene glycol monoalkyl ether, very particularly preferably triethylene glycol monoalkyl ether and tetraethylene glycol monoalkyl ether and in particular triethylene glycol monoalkyl ether.

[0051] In a preferred embodiment, component (B) is a mixture consisting mainly of triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether, in which higher and lower alkylene glycol monoalkyl ethers preferably each make up less than 10% by weight, particularly preferably less than 10% by weight in total. Very particularly 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.

[0052] The proportion of triethylene glycol monoalkyl ether in component (B) is at least 65% by weight, preferably at least 70% by weight, particularly preferably at least 75% by weight and very particularly preferably at least 80% by weight.

[0053] The optional 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)

[0054] HO-[-CH2-CH2-O-]kH where k is an integer of at least 2 and at least 80 wt% of all components of formula (III) k = 2 or 3.

[0055] Examples of such compounds are diethylene glycol, triethylene glycol, tetraethylene glycol and pentaethylene glycol, preferred are diethylene glycol, triethylene glycol and tetraethylene glycol, particularly preferred are diethylene glycol and triethylene glycol.

[0056] Preferably, at least 80% by weight of all components (C) are diethylene glycol and triethylene glycol, more preferably at least 85% by weight, most preferably at least 90% by weight, and especially at least 95% by weight. In a preferred embodiment, at least 60% by weight of component (C) is diethylene glycol, preferably at least 75% by weight, most preferably at least 85% by weight, and especially at least 90% by weight.

[0057] In addition, the brake fluids according to the invention contain as component (D) at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants.

[0058] Preferably, components (D) are selected from the group consisting of alkylamine ethoxylates, alkanolamines, fatty acids, esters of phosphonic acid, esters of phosphoric acid, heterocyclic nitrogen-containing organic compounds, alkylamines, phenothiazine, phenolic compounds, alkoxylates of ricinoleic acid, castor oil or any other ricinoleic acid ester and ethoxylated phenols and Ci-C2o-alkanols with a degree of ethoxylation of 10 to 100.

[0059] Component (D), which may be present in the functional fluid composition, is an additive package, preferably comprising one or more additives with corrosion-inhibiting activity. Preferably, the at least one additive with corrosion-inhibiting activity is selected from alkylamine ethoxylates and alkanolamines, preferably selected from the group consisting of alkylamine ethoxylates and trialkanolamines.

[0060] The alkylamine radical in the alkylamine ethoxylates mentioned can be a secondary or, preferably, a primary aliphatic monoamine that can be ethoxylated. Typically, secondary or, preferably, primary aliphatic monoamines are 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 comprise saturated linear or branched alkyl radicals, but unsaturated linear or branched alkyl radicals or saturated or unsaturated cycloalkyl radicals can also be encompassed by the term "alkyl radical."

[0061] In a preferred embodiment, the alkylamine ethoxylates comprise at least one linear or branched C3 to C20 alkyl chain, preferably at least one linear or branched C1 to C6 alkyl chain, more preferably at least one linear or branched C7 to C12 alkyl chain, most preferably at least one linear or branched C8 to C10 alkyl chain, particularly preferably a linear C8 alkyl chain. The term "alkyl chain" here preferably means saturated and non-cyclic hydrocarbon radicals, more 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.

[0062] Suitable examples of individual alkylamine molecules capable of ethoxylation and 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.

[0063] Such alkyl radicals can originate entirely from petrochemical production, for example technical Cs-Cis-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. Amines, oleylamines or tallow amines can be used as the basis for the alkylamine ethoxylates.

[0064] The degree of ethoxylation is generally 1 to 35 ethylene oxide ("EO") units per alkylamine molecule, i.e., the at least one alkylamine ethoxylate comprises 1 to 35 EO units, preferably 1.5 to 15 EO units, more preferably 1.8 to 9 EO units, most preferably 2 to 6 EO units. The stated degree of ethoxylation is a statistical value, i.e., the alkylamine ethoxylates are normally considered to be species mixtures (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 C3 to C20 alkyl chain and 1 to 35 EO units; particularly preferably, the at least one alkylamine ethoxylate comprises at least one linear Ce to C alkyl chain and 1.5 to 15 EO units; very particularly preferably, the at least one alkylamine ethoxylate comprises at least one linear C7 to Cn alkyl chain and 1.8 to 9 EO units; in particular, the at least one alkylamine ethoxylate comprises at least one linear Cs to Cw alkyl chain and 2 to 6 EO units.

[0065] Such alkylamine ethoxylates can be primary amines with an oxyethylene chain of the general formula alkyl-NH-(CH2CH2O) m -H or primary amines with two oxyethylene chains of the general formula alkyl-N[(CH2CH2O) P H][(CH2CH2O) q -H] or secondary amines of the general formula (Alkyl)2N-(CH2CH2O) mH or mixtures of such primary amines with one oxyethylene chain and such primary amines with two oxyethylene chains, or mixtures of such primary 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 C1 to C6 alkyl, more preferably C7 to C12 alkyl, most preferably C5 to C8 alkyl, as defined above. Other alkylamine species may also be present in minor amounts, especially at low total degrees of ethoxylation below 2.

[0066] A typical suitable alkylamine ethoxylate is octylamine (caprylamine) with 2 EO units, which is commercially available.

[0067] The aforementioned alkylamine ethoxylates can be prepared by conventional methods, such as the reaction of the alkylamine with ethylene oxide catalyzed by alkali metal hydroxides or by double metal cyanides, as known to those skilled in the art. The alkylamine ethoxylates have partial corrosion-inhibiting properties and partial solvent properties for the functional fluid composition or brake fluid according to the present invention.

[0068] Component (D) of the present functional fluid composition may comprise, in addition to the alkylamine ethoxylates, at least one further additive with corrosion-inhibiting action.

[0069] Typical additives with corrosion-inhibiting properties include fatty acids such as lauric, palmitic, stearic or oleic acid; esters of phosphonic acid or phosphoric acid with aliphatic alcohols; phosphites and phosphates 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-(C4- to C20-alkyl)amines, e.g.n-Butylamine, n-hexylamine, n-octylamine, 2-ethylhexylamine, isononylamine, n-decylamine, n-dodecylamine, oleylamine, di-n-propylamine, diisopropylamine, di-n-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. Preferred are triethanolamine and triisopropanolamine, particularly preferred is triisopropanolamine.

[0070] Of course, mixtures of the above-mentioned additives with corrosion-inhibiting effects can also be used.

[0071] In addition to the alkylamine ethoxylates and, if applicable, additives with corrosion-inhibiting effects, other common additives may be included in the additive package of component (D), for example stabilizers such as pH stabilizers, antioxidants such as phenothiazine and phenolic compounds, e.g. hydroxyanisole and bisphenol A, defoamers and dyes.

[0072] In a preferred embodiment, component (D), as a lubricant, comprises at least one alkoxylate of ricinoleic acid, castor oil, or any other ricinoleic acid ester, preferably of ricinoleic acid or castor oil, and most preferably of castor oil. This castor oil, within the meaning of the present description, is an at least partially and preferably fully esterified acylglycerol, wherein at least one, preferably at least two of the acyl groups are ricinoleic acid or isoricinoleic acid, preferably ricinoleic acid.

[0073] 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.

[0074] 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 C5- to C22-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, resulting in random or block structures of alkylene oxide units, can also be used.

[0075] In detail, the structure of the alkoxylate preferably comprises a saturated or unsaturated Cs to C22 fatty monocarboxylic acid or at least one saturated or unsaturated Cs to C22 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 is present in the molecule and carries a hydroxyl group located on the fatty acid side chain of the alkoxylate which is etherified by one or more oxyalkylene units. Examples of such saturated or unsaturated hydroxyl-substituted C5 to C22 fatty monocarboxylic acids or units thereof, preferably saturated or unsaturated hydroxyl-substituted C14 to C20 fatty monocarboxylic acids or units thereof, as a basis for the alkoxylates are 10-hydroxystearic acid, 12-hydroxystearic acid and in particular ricinoleic acid.Such unsaturated hydroxyl-substituted C5- to C22-fatty monocarboxylic acids can be used as free carboxylic acids or as corresponding esters to produce the alkoxylate. In the case of ricinoleic acid, castor oils, as their naturally occurring triglyceride, can advantageously be transesterified with an alkylene oxide, resulting in the desired ricinoleic acid alkoxylate and glycerin. Any other ester of ricinoleic acid can be used as the starting material for the transesterification, e.g., 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, particularly with castor oils, the ester can retain its carboxylic acid ester function and, in particular, its glycerol triester function and is alkoxylated singly or multiply by oxyalkylene units solely at the hydroxy group on the fatty acid side chain.

[0076] The alkoxylate mentioned, especially the alkoxylate of ricinoleic acid, castor oil, or any other ricinoleic acid ester, typically comprises 2 to 200, preferably 4 to 100, more 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 C5- to C22-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 the alkoxylation is based on 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 can be two types of hydroxyl groups in the molecule to be alkoxylated, ie one to be esterified (or transesterified) and the other to be etherified, esterification may or may not occur, etherification will always occur.

[0077] Processes for the 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.

[0078] In a preferred embodiment, the functional fluids according to the invention contain at least one compound selected from the group consisting of benzotriazole, tolutriazole, 1,2,4-triazole and benzoimidazole.

[0079] In a further preferred embodiment, the functional fluids according to the invention additionally or independently contain, preferably additionally, at least one compound selected from the group consisting of alkylamine ethoxylates with a linear Cs to Cw alkyl chain and 2 to 6 EO units, mono-, di- and triisopropanolamine.

[0080] In a further preferred embodiment, the functional fluids according to the invention additionally or independently contain, preferably additionally, at least one 10- to 50-fold ethoxylated alkoxylate of ricinoleic acid, castor oil or another ricinoleic acid ester.

[0081] The defoamers as component (D) are usually ethoxylated phenols and Ci-C2o-alkanols with a degree of ethoxylation of 10 to 100 ethylene oxide ("EO") units per hydroxy group, preferably 15 to 75 times ethoxylated Ci-C2o-alkanols.

[0082] Furthermore, the brake fluid according to the present invention contains at least one organic silicon compound (E) of the formula (IV)

[0083] R 11 x-Si(-[-O-CH2-CH2-]zOR 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,

[0084] R 11 Ci- to C4-alkyl, especially methyl or ethyl, particularly preferably methyl and

[0085] R 12C1- to C4-alkyl, especially methyl or n-butyl, particularly preferably methyl. As explained above, these organic silicon compounds, especially with x = 1 and 2, in particular 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. It is therefore advisable to choose the proportion of component (E) as high as necessary to achieve the desired boiling points, but on the other hand to choose the type and amount of components (A) to (C), and especially (A) and (B) such that they reduce the high viscosity of component (E) but at the same time have sufficiently high wet and dry boiling points themselves to meet the desired target values.

[0086] 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.

[0087] In the compounds (E) the radicals R 11 C1- to C4-alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or ethyl and most preferably methyl. The x radicals R 11 can be the same or different independently of each other, preferably they are the same.

[0088] The number x of residues R 11 is from 1 to 3, preferably 1 or 2 and particularly preferably 2.

[0089] For the substructures H-[-O-CH2-CH2-]zOR 12 are alkylene glycol monoalkyl ethers, as described above for compounds (A) and (B), preferably R 12C1- to C4-alkyl, preferably methyl, ethyl, or n-butyl, particularly preferably methyl or n-butyl, and most preferably methyl. The index z is a positive integer from 2 to 4, preferably 3 or 4, and particularly preferably 3.

[0090] In a preferred embodiment, the substructures are H-[-O-CH2-CH2-]zOR 12 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.

[0091] In a preferred embodiment, the substructures are H-[-O-CH2-CH2- ]zOR 12 the same alkylene glycol monoalkyl ethers as used as components (A) and / or (B), particularly preferably the same alkylene glycol monoalkyl ethers as used as components (A).

[0092] The composition of the functional fluids according to the invention, preferably the brake fluids according to the invention, is as follows:

[0093] Component (E) 40 to 55% by weight, preferably 43 to 55, particularly preferably 45 to 53, very particularly preferably 47 to 52% by weight,

[0094] Component (A) 24 to 45% by weight, preferably 24 to 40, particularly preferably 24 to 35, very particularly preferably 24 to 30% by weight,

[0095] (B) 5 to 20, preferably 7 to 15 wt%,

[0096] (C) 0 to 10 wt%, preferably 0 to 5 wt%,

[0097] (D) more than 0 to 5 wt%, preferably 1 to 4 wt%, with the proviso that the sum of all components (A) to (E) always amounts to 100 wt%.

[0098] A preferred embodiment of the present invention is that the content of glycol (C) in the functional fluids according to the invention does not exceed the production-related proportion of glycol in components (A) and (B), i.e., no additional glycol (C) is added to the functional fluid. Particularly preferably, the proportion of glycol (C) in the functional fluids according to the invention is not more than 1% by weight, particularly preferably not more than 0.75% by weight, and most preferably not more than 0.5% by weight.

[0099] In another preferred embodiment of the present invention, at least one glycol (C) is present, particularly preferably in amounts which exceed the production-related proportion of glycol in components (A) and (B), very particularly preferably in amounts of 1 to 10 wt%, in particular 1 to 5 wt%.

[0100] This embodiment is particularly preferred when the presence of polynuclear organic silicon compounds (see below) is desired.

[0101] The proviso is that in components (A) to (C) and (E)

[0102] - the sum of all alkoxyglycols or glycols with n, m, k and z = 2 is more than 0 (zero) and not more than 10 mol%

[0103] - the sum of all alkoxyglycols or glycols with n, m, k and z = 3 is at least 60 mol%, and

[0104] - the sum of all alkoxyglycols or glycols with n, m, k, and z = 4 amounts to more than 0 mol% to 20 mol%. Furthermore, the proportion of boric acid esters with alkoxyglycols or glycols is not more than 3 wt%, preferably not more than 2.5, particularly preferably not more than 2, most preferably not more than 1.5, in particular not more than 1, and especially not more than 0.5 wt%.

[0105] Since components (A), (B), and (C) contain reactive groups capable of reacting with the organic silicon compounds (E), the composition of the functional fluids according to the invention may change, for example, upon exposure to temperatures higher than room temperature and / or during storage. Furthermore, such a reaction can be accelerated by the presence of amines as additives (D).

[0106] This change in composition can, on the one hand, be due to the exchange of the substructures H-[-O-CH2-CH2-]ZOR 12in 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-CH2-CH2-]zOR 12 in the composition.

[0107] On the other hand, in the presence of difunctional diglycols (C), polynuclear organic silicon compounds, i.e., compounds containing more than one silicon atom, can also form. For example, dinuclear or trinuclear silicon compounds can form, while higher-nuclear silicon compounds form only in small amounts; binuclear silicon compounds are preferentially formed.

[0108] The structure of such dinuclear silicon compounds is, for example, as follows:

[0109] R 11 x-Si(-[-O-CH2-CH2-]zOR 12 )4-xi-(-O-[-CH2-CH2-O-] k -)-Si R 11 x (-[-O-CH2-CH2-]ZOR 12)4-XI where the variables are defined as above. Here, x must be at least 2.

[0110] The structure of trinuclear silicon compounds, for example, is as follows: 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 starting from the initial composition in thermodynamic equilibrium.

[0111] Accordingly, the present invention further provides a reaction mixture obtainable by reacting components (A) to (E) with one another. If diglycols (C) are present, this reaction mixture may also contain polynuclear silicon compounds, for example di- and trinuclear, preferably dinuclear silicon compounds.

[0112] The composition of the reaction mixture lies between the initial composition and the composition in thermodynamic equilibrium.

[0113] The mixtures according to the invention can be used as functional fluids, for example as hydraulic fluids or in particular as brake fluids.

[0114] These brake fluids are particularly suitable for use in vehicles with hydraulic braking systems, such as passenger cars or commercial vehicles. These brake fluids are particularly suitable for electronic or automatic braking systems with anti-lock braking systems, which require brake fluids with low viscosity even at low temperatures.

[0115] The following examples demonstrate the scope and benefits of the compositions of the invention without limiting them to these examples.

[0116] Examples

[0117] As an example of a brake fluid, Castrol React SRF Racing was used with a Si content of approximately 8.0 wt% + / - 0.3 wt% (within the measurement accuracy range) determined by ICP-OES. This essentially corresponds to a pure silicone ester with triethylene glycol monoalkyl ether as the incorporated alkoxyglycol (compound (E) with x = 2, z = 3 and R 11 and R 12 (each C1- to C4-alkyl). This is referred to here as component 1.

[0118] The following formulations were prepared and their properties were determined as follows: Dry boiling point (ERBP) according to ASTM D1120

[0119] Wet boiling point (WERBP) according to SAE J1703 Kinematic viscosity according to ASTM D445, unless otherwise stated at -40 °C Example 1

[0120] MTG: Triethylene glycol monomethyl ether (compound (A), n = 3)

[0121] BTG: Triethylene glycol monobutyl ether (compound (B), m = 3, R 1 = n-butyl)

[0122] MTG borate: boric acid ester of MTG (B(MTG)s)

[0123] 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 a significantly higher low-temperature viscosity (entries 1 vs. 4).

[0124] When blended with alkyl glycol ethers, the silicone ester-based blends retain their advantage in ERBP and WERBP and even extend it, whereby the viscosity can be reduced almost to the level of the boric acid ester-based blends (entries 2 vs.

[0125] 5 and 3 vs. 6).

[0126] Example 2

[0127] A formulation with the following composition (in wt%) was prepared:

[0128] BTG: Triethylene glycol mono-n-butyl ether (compound (B), m = 3, R 1 = n-butyl)

[0129] MTG: Triethylene glycol monomethyl ether (compound (A), n = 3)

[0130] MTeG: Tetraethylene glycol monomethyl ether (compound (A), n = 4)

[0131] DEG: Diethylene glycol (compound (C), k = 2)

[0132] 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%, amine antioxidant as heat stabilizer 1.5% dissolved in 83.25% MTG

[0133] Furthermore, examples 3, 4, 6 and 8 given in Research Disclosure 694049, published on 17 January 2022, were reproduced and their viscosity at -40 °C [mm 2 / s], ERBP [°C] and WERBP [°C] as determined in Example 2:

[0134] Comparative example RD3 has a similar content of component 1 and MTG as inventive example 2, but contains 24 wt% BTG, whereas in inventive example 2 the content of BTG is only 10 wt%, but it also has a content of MTeG of 10 wt%.

[0135] This leads to approximately comparable results for the viscosity at -40 °C and the dry boiling point (ERBP), but the inventive example 2 has a wet boiling point (WERBP) that is 13 °C higher than the comparative example RD3.

[0136] Thus, MTeG as inventive component (A) with n = 4 exhibits a more favorable effect on the wet boiling point than an increased content of triethylene glycol mono-n-butyl ether (BTG), while simultaneously maintaining the good values ​​for viscosity and dry boiling point. Comparative Example RD8 has a similar content of Component 1 and MTG as Inventive Example 3, but contains only 2 wt% BTG, whereas in Inventive Example 2 the BTG content is 10 wt%.

[0137] This leads to approximately comparable results for the viscosity at -40 °C and the dry boiling point (ERBP), but the inventive example 3 has a 4 °C higher wet boiling point (WERBP) than the comparative example RD8. Thus, an increased content of BTG (component (B), m = 3, R 1 = Butyl) has a favorable influence on the wet boiling point while maintaining the good values ​​for viscosity and dry boiling point.

Claims

Patent claims 1. Functional fluids with a viscosity at -40 °C according to FMVSS 116 of not more than 750 cSt (mm²). 2 / s), containing (A) at least one alkoxyglycol according to formula (I) H3C-O-[-CH2-CH2-O-] n -H where n is an integer from 2 to 5 and for at least 30 wt% of all components of formula (I) n = 3 holds, (B) at least one alkoxyglycol according to formula (II) R 1 -O-[-CH2-CH2-O-]mH wherein R 1 C2- to C4-alkyl, m is an integer from 2 to 6 and m = 3 applies to at least 65 wt% of all components of formula (II), (C) optionally at least one glycol according to formula (III) HO-[-CH2-CH2-O-]kH where k is an integer of at least 2 and for at least 80 wt% of all components of formula (III) k = 2 or 3 holds, (D) at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants, (E) at least one silicon organic compound of formula (IV) R 11 x-Si(-[-O-CH2-CH2-] z -OR 12 )4-x wherein x a positive integer 1, 2 or 3, preferably 2; z an integer from 2 to 4 R 11 Ci- to C4-alkyl, especially methyl or ethyl, particularly preferably methyl and R 12 Ci- to C4-alkyl, especially methyl or n-butyl, particularly preferably methyl, wherein the proportion of (E) 40 to 55 wt%, preferably 43 to 55, particularly preferably 45 to 53, most particularly preferably 47 to 52 wt%, (A) 24 to 45 wt%, (B) 5 to 20, preferably 7 to 15 wt%, (C) 0 to 10 wt%, preferably 0 to 5 wt%, (D) is more than 0 to 5 wt%, provided that the sum of all components (A) to (E) always equals 100 wt%, characterized in that components (A) to (C) and (E) - the sum of all alkoxyglycols or glycols with n, m, k and z = 2 is greater than 0 (zero) and not more than 10 mol% - the sum of all alkoxyglycols or glycols with n, m, k and z = 3 at least 60 mol%, and - the sum of all alkoxyglycols or glycols with n, m, k and z = 4 constitutes more than 0 mol% to 20 mol% and - the proportion of boric acid esters with alkoxy glycols 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, particularly preferably at least 85%, most preferably at least 90%, in particular especially if it is at least 95% by weight.

4. 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.

5. 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.

6. 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 nitrogenous organic compounds and alkoxylates of ricinoleic acid, castor oil or any other ricinoleic acid ester.

7. Composition according to one of the preceding claims, characterized in that in component (E) x = 2.

8. Composition according to one of the preceding claims, characterized in that component (E) R 11 Methyl is.

9. Composition according to one of the preceding claims, characterized in that z = 3 in component (E).

10. Composition according to one of the preceding claims, characterized in that component (E) R 12 Methyl is.

11. Composition according to one of the preceding claims, characterized in that the substructures are H-[-O-CH2-CH2-]zOR 12 Component (E) is the same alkylene glycol monoalkyl ether as used as components (A) and / or (B), particularly preferably the same alkylene glycol monoalkyl ether as used as components (A).

12. Reaction mixture obtainable by reacting components (A) to (E) according to any one of the preceding claims with each other.

13. Reaction mixture according to claim 12, comprising at least one diglycol (C) and at least one polynuclear silicon compound, for example, a dinuclear and trinuclear, preferably a dinuclear silicon compound.

14. Reaction mixture according to claim 13, characterized in that the polynuclear The silicon compound was selected from the group consisting of R 11 x-Si(-[-O-CH2-CH2-]zOR 12 )4-xi-(-O-[-CH2-CH2-O-]k -)-Si R 11 x (-[-O-CH2-CH2-] Z -O- R 12 )4-xi and wherein the variables are defined as in any of the preceding claims and x is at least 2.

15. Use of the compositions and reaction mixtures according to any one of the preceding claims as a functional fluid, preferably as a hydraulic fluid or Brake fluid.

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