Novel low-viscosity functional liquid

Abstract

The invention relates to a low-viscosity functional fluid, in particular a brake fluid, based on organosilicon compounds and alkoxy ethylene glycol.

Description

[0001] manual

[0002] The invention describes a low-viscosity functional fluid, in particular a brake fluid, based on an organosilicon compound and an alkoxy glycol.

[0003] These brake fluids have high dry and wet boiling points and low low-temperature viscosity, which makes them particularly suitable for use in modern brake systems.

[0004] Typical functional fluids contain mixtures of alkoxy glycols and their boric acid esters. These are widely used as brake fluids. The growing demands on brake fluids are for higher dry and wet boiling points, while reducing viscosity.

[0005] The current requirements according to DOT 5.1 are that the dry boiling point and wet boiling point are greater than 260°C and 180°C respectively, and the kinematic viscosity at -40°C is less than 900mm 2 / s.

[0006] At least one silicone ester-based brake fluid is freely available on the market which has a silicon content of 8% by weight, ie is essentially a pure reaction product of an organosilicon compound with an alkoxy glycol.

[0007] According to the product data sheet, the product has very high dry and wet boiling points of 320°C and 270°C respectively, but has a 1300mm 2 / s high kinematic viscosity and therefore does not meet the requirements of DOT 5.1.

[0008] Such silicone ester-based fluids and their use as hydraulic oils are known from DE-OS 2147853. In the examples, silicone esters are used in pure form or in mixtures with boric esters and alkoxy glycols. Mixtures of silicone esters with alkoxy glycols are not described.

[0009] Research publication 694049, published on January 17, 2022, describes compositions of silicone esters and alkoxy glycols. Neither the wet or dry boiling points nor the viscosities of these compositions are given, so the suitability of these compositions as brake fluids cannot be assessed.

[0010] The object of the present invention is to develop a brake fluid which maintains the advantages of high dry and wet boiling points of silicone ester-based compounds and reduces the viscosity to at least the low level required by DOT 5.1, preferably to not more than 750 cSt (mm2) at -40°C as required by ISO 4925 Grade 6. 2 / s) kinematic viscosity.

[0011] Functional fluids with a viscosity of no more than 750 cSt at -40°C according to FMVSS116 solve this problem and include:

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

[0013] H3C-O-[-CH2-CH2-O-] n -H

[0014] in,

[0015] n is an integer from 2 to 5, and

[0016] For at least 30% by weight of all components of formula (I), n=3,

[0017] (B) at least one alkoxy glycol according to formula (II)

[0018] R 1 -O-[-CH2-CH2-O-] m -H

[0019] in,

[0020] R 1 is a C2 to C4 alkyl group,

[0021] m is an integer from 2 to 6, and

[0022] For at least 65% by weight of all components of formula (II), m=3,

[0023] (C) optionally at least one ethylene glycol, according to formula (III)

[0024] HO-[-CH2-CH2-O-] k -H

[0025] in,

[0026] k is an integer at least 2, and

[0027] For at least 80% by weight of all components of formula (III), k=2 or 3,

[0028] (D) at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants,

[0029] (E) at least one organosilicon compound according to formula (IV)

[0030] R 11 x -Si(-[-O-CH2-CH2-] z -OR 12 ) 4-x

[0031] in,

[0032] x is a positive integer 1, 2 or 3, preferably 2,

[0033] z is an integer from 2 to 4,

[0034] R 11 is C1 to C4 alkyl, in particular methyl or ethyl, particularly preferably methyl, and

[0035] R 12 is C1 to C4 alkyl, in particular methyl or n-butyl, particularly preferably methyl,

[0036] in,

[0037] The proportion of (E) is 40% to 55% by weight, preferably 43% to 55% by weight, particularly preferably 45% to 53% by weight, very particularly preferably 47% to 52% by weight,

[0038] The proportion of (A) is 24 wt % to 45 wt %,

[0039] The proportion of (B) is 5 to 20% by weight, preferably 7 to 15% by weight,

[0040] The proportion of (C) is 0% to 10% by weight, preferably 0% to 5% by weight,

[0041] (D) has a ratio of more than 0% by weight to 5% by weight,

[0042] Provided that the sum of all components (A) to (E) is always equal to 100% by weight,

[0043] Among the components (A) to (C) and (E),

[0044] - The sum of all alkoxy glycols or glycols with n, m, k and z = 2 is greater than 0 (zero)

[0045] and not more than 10 mol%.

[0046] - the sum of all alkoxy glycols or glycols with n, m, k and z = 3 is at least 60 mol %, and

[0047] - The sum of all alkoxy glycols or glycols with n, m, k and z = 4 is greater than 0 mol %

[0048] to 20 mol%.

[0049] and

[0050] - The ratio of boric acid ester to alkoxyglycol or ethylene glycol does not exceed 3% by weight.

[0051] Although silicone ester-based compounds have high dry and wet boiling points, but the viscosity is too high, low molecular weight glycols or alkoxy glycols do have low viscosity, but also have low boiling points. However, the higher the degree of alkoxylation of the alkoxy glycol, the more its boiling point increases, but at the same time it also loses the advantage of low viscosity.

[0052] However, the functional liquid according to the present invention has a low viscosity with high dry boiling point and wet boiling point values ​​that meet the above requirements. These properties are achieved by a balanced and coordinated selection of components with high dry boiling point and wet boiling point and low viscosity. In particular, the degree of alkoxylation of the glycol or alkoxy glycol is selected so that these compounds meet a compromise of sufficiently high boiling point and sufficiently low viscosity.

[0053] It has been found that glycols and alkoxy glycols based on triethylene glycol provide this compromise between low viscosity and high dry or wet boiling points and therefore these materials comprise at least 60% of the functional liquid.

[0054] Although diethylene glycol-based ethylene glycol and alkoxy ethylene glycol have low viscosity, they lower the required boiling point so that the proportion thereof does not exceed 10%.

[0055] In contrast, ethylene glycol and alkoxyethylene glycol based on tetraethylene glycol have a high boiling point but at the same time have a relatively high viscosity, so the proportion thereof does not exceed 20%.

[0056] Due to its two free hydroxyl groups, ethylene glycol has a relatively high viscosity, so its content in the functional liquid should not exceed 10% by weight, preferably 5% by weight.

[0057] The percentage data are based on the mol % of the respectively mentioned oligomers in components (A), (B), (C) and (E), wherein the (4-x) times of alkoxyglycol in component (E) must be taken into account.

[0058] These components are described in detail below:

[0059] Component (A) is at least one alkoxy glycol of formula (I)

[0060] H3C-O-[-CH2-CH2-O-] n -H

[0061] in,

[0062] n is an integer of 2 to 5, preferably 2 to 4, particularly preferably 3 or 4, and

[0063] For at least 30% by weight of all components of formula (I), n=3.

[0064] These may be one to four, preferably one to three, particularly preferably one or two, very particularly preferably one alkoxyglycol.

[0065] Typical components (A) are diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether and pentaethylene glycol monomethyl ether.

[0066] Among them, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether are preferred, triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether are particularly preferred, and triethylene glycol monomethyl ether is very particularly preferred.

[0067] Usually, component (A) is a mixture consisting mainly of triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, wherein the higher and lower alkylene glycol monomethyl ethers are preferably less than 10% by weight each, particularly preferably less than 10% by weight in total. Very particularly preferably, component (A) is mainly triethylene glycol monomethyl ether, wherein the higher and lower alkylene glycol monomethyl ethers are preferably less than 20% by weight each, particularly preferably less than 10% by weight in total.

[0068] 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 very particularly preferably at least 60% by weight.

[0069] 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 and in particular at least 95% by weight.

[0070] Component (B) is at least one alkoxy glycol of formula (II),

[0071] R 1 -O-[-CH2-CH2-O-] m -H

[0072] in,

[0073] R 1 is C2 to C4 alkyl, preferably ethyl, n-propyl, n-butyl, particularly preferably ethyl and n-butyl, very particularly preferably n-butyl,

[0074] m is an integer from 2 to 6, preferably from 2 to 5, particularly preferably from 2 to 4, very particularly preferably 3 or 4, and

[0075] For at least 65% by weight of all components of formula (II), m=3,

[0076] These may be one to five, preferably one to four, particularly preferably one to three, very particularly preferably one or two, in particular one, alkoxyglycol.

[0077] 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, very particularly preferably oligoethylene glycol mono-n-butyl ether.

[0078] 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, very particularly preferably triethylene glycol monoalkyl ethers and tetraethylene glycol monoalkyl ethers, in particular triethylene glycol monoalkyl ethers.

[0079] 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, wherein the higher and lower alkylene glycol monoalkyl ethers are preferably less than 10% by weight each, particularly preferably less than 10% by weight in total. Very particularly preferably, component (B) is mainly triethylene glycol mono-n-butyl ether, wherein the higher and lower alkylene glycol monoalkyl ethers are preferably less than 20% by weight each, particularly preferably less than 10% by weight in total.

[0080] 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.

[0081] Optional component (C) is at least one glycol, for example one to four, preferably one to three, particularly preferably one or two, very particularly preferably a compound of formula (III)

[0082] HO-[-CH2-CH2-O-] k -H

[0083] in,

[0084] k is an integer at least 2, and

[0085] For at least 80% by weight of all components of the formula (III), k=2 or 3.

[0086] Examples of such compounds are diethylene glycol, triethylene glycol, tetraethylene glycol and pentaethylene glycol, preferably diethylene glycol, triethylene glycol and tetraethylene glycol, particularly preferably diethylene glycol and triethylene glycol.

[0087] Preferably, at least 80% by weight of all components (C) are diethylene glycol and triethylene glycol, particularly preferably at least 85% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight. In a preferred embodiment, component (C) comprises at least 60% by weight of diethylene glycol, preferably at least 75% by weight, very particularly preferably at least 85% by weight, in particular at least 90% by weight.

[0088] Furthermore, the brake fluid according to the present invention further comprises, as component (D), at least one additive selected from the group consisting of corrosion inhibitors, amines, stabilizers, defoamers and lubricants.

[0089] Component (D) is preferably selected from alkylamine ethoxylates, alkanolamines, fatty acids, phosphonates, phosphoric esters, nitrogen-containing heterocyclic organic compounds, alkylamines, phenothiazines, phenolic compounds, alkoxylates of ricinoleic acid, castor oil or any other ricinoleic acid ester and ethoxylated phenols and C1-C20 alkanols having a degree of ethoxylation of 10 to 100.

[0090] Component (D) that may be present in the functional liquid composition is an additive package, which preferably comprises one or more additives having a corrosion inhibiting effect. Preferably, at least one additive having a corrosion inhibiting effect is selected from alkylamine ethoxylates and alkanolamines, preferably from alkylamine ethoxylates and trialkanolamines.

[0091] The alkylamine residue in the alkylamine ethoxylate may be a secondary or preferably primary aliphatic monoamine, which may be ethoxylated. Secondary or preferably primary aliphatic monoamines are usually used, but polyamines having at least one secondary and / or primary amino group which may be ethoxylated may also be used. The alkyl residue on the nitrogen atom usually includes a saturated straight-chain or branched alkyl residue, but the term "alkyl residue" may also include an unsaturated straight-chain or branched alkyl residue or a saturated or unsaturated cycloalkyl residue.

[0092] In a preferred embodiment, the alkylamine ethoxylate comprises at least one linear or branched C3 to C 20 Alkyl chain, preferably at least one linear or branched C6 to C 13 Alkyl chain, particularly preferably at least one linear or branched C7 to C 12 Alkyl chain, most preferably at least one linear or branched C8 to C 10 Alkyl chains, particularly preferably straight-chain C8 alkyl chains. The term "alkyl chain" here preferably means saturated and non-cyclic hydrocarbon residues, particularly preferably straight-chain unbranched alkyl residues. The alkylamine ethoxylates may also contain mixtures of such alkyl chains, for example mixtures of homologous alkyl residues, depending on the specific industrial or natural source of the alkylamine used.

[0093] Suitable examples of single alkylamine molecules that can be ethoxylated and are also suitable as surfactants of 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-(undecyl)amine, di-(n-dodec ... methylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-nonadecylamine, n-eicosylamine, n-hexylmethylamine, n-heptylmethylamine, n-octylmethylamine, 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.

[0094] Such alkyl residues can be derived entirely from petrochemical production, such as industrial grade C8-C 15 Alkyl mixtures, 2-ethylhexyl or 2-propylheptyl, or completely or partly based on renewable raw materials, for example fatty amines, such as stearyl, amine, oleylamine or tallowamine can be used as base for the alkylamine ethoxylates.

[0095] 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, and most preferably 2 to 6 EO units. The degree of ethoxylation is a statistical value, i.e., the alkylamine ethoxylate is generally regarded as a mixture 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 C3 to C 20 alkyl chain and 1 to 35 EO units; particularly preferably, the at least one alkylamine ethoxylate comprises at least one linear C6 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 C7 to C 11alkyl chain and 1.8 to 9 EO units; in particular, the at least one alkylamine ethoxylate comprises at least one linear C8 to C 10 alkyl chain and 2 to 6 EO units.

[0096] Such alkylamine ethoxylates may be of the general formula alkyl-NH-(CH2CH2O) m -H primary amines with ethylene oxide chains, or alkyl-N[(CH2CH2O) p H][(CH2CH2O) q -H], or a primary amine having two oxyethylene chains, or having the general formula (alkyl)2N-(CH2CH2O) m H, or a mixture of a primary amine having an oxyethylene chain and a primary amine having two oxyethylene chains, or a mixture of a primary amine and a secondary amine, wherein m and (p+q) are the total degree of ethoxylation, respectively. The "alkyl" in the above formula generally represents a C3 to C 20 Alkyl, preferably C6 to C 13 Alkyl, more preferably C7 to C 12 Alkyl, most preferably C8 to C 10 Other alkylamine species may also be present in small amounts, particularly when the overall degree of ethoxylation is less than 2.

[0097] A typical suitable alkylamine ethoxylate is the commercially available octylamine (octylamine) having 2 EO units.

[0098] The alkylamine ethoxylates can be prepared by conventional methods, such as the reaction of alkylamines with ethylene oxide under alkali metal hydroxide catalysis or under double metal cyanide catalysis, as known to those skilled in the art. For the functional liquid composition or brake fluid according to the invention, the alkylamine ethoxylates have partial corrosion inhibition properties and partial solvent properties.

[0099] In addition to the alkylamine ethoxylate, component (D) of the present functional liquid composition may further contain at least one other additive having a corrosion inhibiting effect.

[0100] Conventional additives having corrosion-inhibiting properties are, in particular, fatty acids, for example lauric acid, palmitic acid, stearic acid or oleic acid; esters of phosphonic acid or phosphoric acid with fatty 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 the abovementioned alkoxyglycols as component (A) or (B), heterocyclic nitrogen-containing organic compounds, such as benzotriazole, toluenetriazole, 1,2,4-triazole, benzimidazole , purine, adenine and derivatives of such heterocyclic organic compounds; alkylamines, such as mono- and di-(C4- to C20-alkyl)amines, such as n-butylamine, n-hexylamine, n-octylamine, 2-ethylhexylamine, isononylamine, n-decylamine, n-dodecylamine, oleylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, di-n-pentylamine, cyclohexylamine and salts of these alkylamines; alkanolamines, such as mono-, di- and tri-methanolamine, mono-, di- and triethanolamine, mono-, di- and tri-n-propanolamine, and mono-, di- and tri-isopropanolamine. Triethanolamine and triisopropanolamine are preferred, and triisopropanolamine is particularly preferred.

[0101] Of course, it is also possible to use mixtures of the abovementioned additives having a corrosion-inhibiting effect.

[0102] In addition to the alkylamine ethoxylates and optional additives having a corrosion-inhibiting effect, the additive package of component (D) may also comprise other conventional additives, for example stabilizers such as pH stabilizers, antioxidants such as phenothiazines and phenolic compounds such as hydroxyanisole and bisphenol A, defoamers and colorants.

[0103] In a preferred embodiment, component (D) comprises as lubricant at least one alkoxylate of ricinoleic acid, castor oil or any other ricinoleic acid ester, preferably ricinoleic acid or castor oil, very particularly preferably castor oil. Castor oil in the sense 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 is ricinoleic acid or isoricinoleic acid, preferably ricinoleic acid.

[0104] For example, the fatty acid mixture preferably comprises a mixture of two ricinoleic acid molecules with a fatty acid not carrying a hydroxyl group, preferably selected from oleic acid, linoleic acid, palmitic acid and stearic acid.

[0105] In a preferred embodiment, the OH value of castor oil is 160 mg KOH / g to 173 mg KOH / g. Alkoxylates of ricinoleic acid, castor oil or any other ricinoleic acid ester are preferably C8 to C6 substituted with saturated or unsaturated hydroxyl groups. 22The reaction of fatty acids or their esters is particularly carried out 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. It is also possible to use mixtures of such alkylene oxides which result in random or block structures of alkylene oxide units.

[0106] Specifically, the structure of the alkoxylate preferably contains a saturated or unsaturated C8 to C 22 Fatty monocarboxylic acid or at least one saturated or unsaturated C8 to C 22 Fatty monocarboxylic acid units, esterified with one or more oxyalkylene groups having a free carboxylic acid function, if such a free carboxylic acid function is present in the molecule and with a hydroxyl group located on the fatty acid side chain of the alkoxylate, which hydroxyl group is etherified with one or more oxyalkylene units. Such saturated or unsaturated hydroxyl-substituted C8 to C6 hydrocarbons as bases of the alkoxylates 22 Fatty monocarboxylic acid or its unit, preferably saturated or unsaturated hydroxy substituted C 14 To C 20 Examples of fatty monocarboxylic acids or units thereof are 10-hydroxystearic acid, 12-hydroxystearic acid and, in particular, ricinoleic acid. 22 Fatty monocarboxylic acids can be used as free carboxylic acids or as the corresponding esters for the preparation of alkoxylates. In the case of ricinoleic acid, castor oil as its naturally occurring triglyceride can advantageously be reacted with oxyalkylene groups by transesterification, which leads to the desired ricinoleic acid alkoxylate and glycerol. Any other ester of ricinoleic acid, such as the corresponding diglycerides or monoglycerides or the corresponding methyl, ethyl, propyl or butyl esters, can be used as starting materials for the transesterification. Depending on the conditions of the alkoxylation reaction with ricinoleic acid esters, in particular castor oil, the esters can retain their carboxylic acid ester, in particular their triglyceride functions, and only be alkoxylated once or multiple times by oxyalkylene units at the hydroxyl groups of the fatty acid side chains.

[0107] The alkoxylates, in particular alkoxylates of ricinoleic acid, castor oil or any other ricinoleic acid ester, generally contain 2 to 200, preferably 4 to 100, particularly preferably 6 to 80, most preferably 10 to 50, in particular 20 to 40 oxyalkylene units, which are preferably ethylene oxide units. The "number of oxyalkylene units" refers to the number of C8 to C6 substituted alkylene units per mole of saturated or unsaturated hydroxyl groups. 22The number of moles of alkylene oxide in the units of the fatty monocarboxylic acid or thereof as the base of the alkoxylate. Using castor oil, which is a triglyceride of ricinoleic acid, the amount of alkylene oxide used for alkoxylation refers to 3 equivalents of ricinoleic acid or its units to be alkoxylated. At higher degrees of alkoxylation, the number of alkylene units is an average value as a random number caused by the distribution of alkoxylated homologues in the product. There may be two hydroxyl groups in the molecule to be alkoxylated, one to be esterified (or transesterified) and the other to be etherified. Esterification may or may not occur, but etherification always occurs.

[0108] Processes for the alkoxylation, in particular the ethoxylation, of carboxylic acids or esters thereof, such as castor oil, are known in the prior art and therefore do not require further description in the present application.

[0109] In a preferred embodiment, the functional liquid according to the present invention comprises at least one compound selected from benzotriazole, toluenetriazole, 1,2,4-triazole and benzimidazole.

[0110] In another preferred embodiment, the functional liquid according to the present invention additionally or independently preferably further comprises at least one selected from the group consisting of linear C8 to C 10 Compounds of alkylamine ethoxylates, monoisopropanolamine, diisopropanolamine and triisopropanolamine with an alkyl chain and 2 to 6 EO units.

[0111] In another preferred embodiment, the functional liquid according to the invention additionally or independently, preferably additionally comprises at least 10 to 50 times ethoxylated alkoxylate of ricinoleic acid, castor oil or another ricinoleic acid ester.

[0112] The defoaming agent as component (D) is usually ethoxylated phenol and C1-C 20 Alkyl alcohols having a degree of ethoxylation of 10 to 100 ethylene oxide ("EO") units per hydroxyl group, preferably 15 to 75 times ethoxylated C1-C 20 Alkyl alcohol.

[0113] Furthermore, the brake fluid according to the invention further comprises at least one organosilicon compound (E) of the formula (IV)

[0114] R 11 x -Si(-[-O-CH2-CH2-] z -OR 12 ) 4-x

[0115] in,

[0116] x is a positive integer of 1, 2 or 3, preferably 1 or 2, particularly preferably 2,

[0117] z is an integer from 2 to 4, preferably 3.

[0118] R 11 is C1 to C4 alkyl, in particular methyl or ethyl, particularly preferably methyl, and

[0119] R 12 is C1 to C4 alkyl, in particular methyl or n-butyl, particularly preferably methyl,

[0120] As mentioned above, these organosilicon compounds, especially x=1 and 2, especially x=2, have high wet and dry boiling points. Therefore, the presence of these compounds (E) in the brake fluid increases its boiling point, but generally also increases its viscosity. Therefore, the goal is to select the proportion of component (E) as high as required to achieve the desired boiling point, but on the other hand, to select the type and amount of components (A) to (C), especially (A) and (B), so that they reduce the high viscosity of component (E), but at the same time themselves have a sufficiently high wet and dry boiling point to meet the desired target values.

[0121] For this purpose, the brake fluid according to the invention comprises at least one organosilicon compound (E), preferably one to four, particularly preferably one to three, very particularly preferably one or two, in particular one.

[0122] In compound (E), the residue R 11 It can be C1 to C4 alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or ethyl, very particularly preferably methyl. 11 They may be independently the same or different from each other, preferably the same.

[0123] Residue R 11 The number x is 1 to 3, preferably 1 or 2, particularly preferably 2.

[0124] Substructure H-[-O-CH2-CH2-] z -OR 12 is an alkylene glycol monoalkyl ether, as described above for compounds (A) and (B), preferably R 12 is C1 to C4 alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl, very particularly preferably methyl. The operating index z is a positive integer from 2 to 4, preferably 3 or 4, particularly preferably 3.

[0125] In a preferred embodiment, the substructure H-[-O-CH2-CH2-] z -OR 12Selected from 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, preferably triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether, particularly preferably triethylene glycol monomethyl ether and triethylene glycol mono-n-butyl ether.

[0126] In a preferred embodiment, the substructure H-[-O-CH2-CH2-] z -OR 12 The alkylene glycol monoalkyl ether is the same as that used as component (A) and / or (B), and the alkylene glycol monoalkyl ether is particularly preferably the same as that used as component (A).

[0127] The composition of the functional fluid according to the present invention, preferably the brake fluid according to the present invention, is as follows:

[0128] Component (E) 40% to 55% by weight, preferably 43% to 55% by weight, particularly preferably 45% to 53% by weight, very particularly preferably 47% to 52% by weight,

[0129] Component (A) 24% to 45% by weight, preferably 24% to 40% by weight, particularly preferably 24% to 35% by weight, very particularly preferably 24% to 30% by weight,

[0130] The proportion of (B) is 5 to 20% by weight, preferably 7 to 15% by weight,

[0131] The proportion of (C) is 0% to 10% by weight, preferably 0% to 5% by weight,

[0132] (D) is greater than 0% by weight to 5% by weight, preferably 1% by weight to 4% by weight,

[0133] The proviso is that the sum of all components (A) to (E) always equals 100% by weight.

[0134] In a preferred embodiment of the present invention, the content of ethylene glycol (C) in the functional liquid according to the present invention does not exceed the preparation ratio of ethylene glycol in components (A) and (B), i.e., no additional ethylene glycol (C) is added to the functional liquid. The proportion of ethylene glycol (C) in the functional liquid according to the present invention is particularly preferably not more than 1% by weight, particularly preferably not more than 0.75% by weight, and very particularly preferably not more than 0.5% by weight.

[0135] In another preferred embodiment of the present invention, at least one ethylene glycol (C) is present, particularly preferably in an amount that exceeds the production proportion of ethylene glycol in components (A) and (B), very particularly preferably in an amount of 1% to 10% by weight, in particular 1% to 5% by weight.

[0136] This embodiment is particularly preferred if the presence of a multinuclear organosilicon compound is desired (see below).

[0137] In this case, there is a proviso that components (A) to (C) and (E) constitute.

[0138] - The sum of all alkoxy glycols or glycols with n, m, k and z = 2 is greater than 0 (zero)

[0139] and not more than 10 mol%.

[0140] - the sum of all alkoxy glycols or glycols with n, m, k and z = 3 is at least 60 mol %, and

[0141] - The sum of all alkoxy glycols or glycols with n, m, k and z = 4 is greater than 0 mol %

[0142] to 20 mol%.

[0143] Furthermore, the proportion of boric acid ester to alkoxyglycol or ethylene glycol is not more than 3% by weight, preferably not more than 2.5% by weight, particularly preferably not more than 2% by weight, very particularly preferably not more than 1.5% by weight, in particular not more than 1% by weight, in particular not more than 0.5% by weight.

[0144] Since components (A), (B) and (C) contain reactive groups capable of reacting with organosilicon compounds (E), the composition of the functional liquid according to the invention can be changed, for example at temperatures above room temperature and / or during storage. In addition, the presence of amines as additives (D) can accelerate this reaction.

[0145] This modification of the composition may on the one hand comprise replacing the substructure H-[-O-CH2-CH2-] in component (E) with alkylene glycol monoalkyl ethers (A) and (B). z -OR 12 , so that the alkylene glycol monoalkyl ether (A) and (B) are combined into the component (E), and a free alkylene glycol monoalkyl ether H-[-O-CH2-CH2-] is formed in the composition. z -OR 12 .

[0146] On the other hand, in the presence of difunctional diethylene glycol (C), polynuclear organosilicon compounds, i.e. compounds carrying more than one silicon atom, may also be formed. For example, dinuclear or trinuclear silicon compounds may be formed, with high-nuclear silicon compounds only being formed in small amounts, preferably dinuclear silicon compounds.

[0147] The structure of this binuclear silicon compound is, for example, as follows:

[0148] R11 x -Si(-[-O-CH2-CH2-] z -OR 12 ) 4-x-1 -(-O-[-CH2-CH2-O-] k -)-Si R 11 x (-[-O-CH2-

[0149] CH2-] z -OR 12 ) 4-x-1

[0150] where the variables are defined as above. In this case, x must be at least 2.

[0151] For example, the structure of a trinuclear silicon compound is as follows:

[0152] R 11 x -Si(-[-O-CH2-CH2-] z -OR 12 ) 4-x-1 -(-O-[-CH2-CH2-O-] k -)-Si R 11 x (-[-O-CH2-CH2-] z -OR 12 ) 4-x-2 -(-O-[-CH2-CH2-O-] k -)-Si R 11 x (-[-O-CH2-CH2-] z -OR 12 ) 4-x-1 where the variables are defined as above. In this case, x must be at least 2.

[0153] The end point of this change is the composition of the mixture of all components (A) to (E) which, starting from the initial composition, is in thermodynamic equilibrium.

[0154] The invention therefore also provides a reaction mixture obtainable by reacting components (A) to (E) with one another. If diethylene glycol (C) is present, the reaction mixture may also comprise polynuclear silicon compounds, such as dinuclear and trinuclear, preferably dinuclear silicon compounds.

[0155] The composition of the reaction mixture is between the initial composition and the thermodynamic equilibrium composition.

[0156] The mixture according to the invention can be used as functional fluid, for example as hydraulic fluid or in particular as brake fluid.

[0157] Brake fluids can be used particularly advantageously in vehicles with hydraulic brake systems, such as passenger cars 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 viscosity even at low temperatures.

[0158] The following examples show the scope and benefits of the compositions according to the invention without being reduced to these examples. Example

[0159] As an example of a brake fluid, Castrol React SRF Racing was used, the Si content of which was determined by ICP-OES to be approximately 8.0 wt. % + / - 0.3 wt. % (within the measurement accuracy). Calculated, this corresponds essentially to a pure silicone ester with triethylene glycol monoalkyl ether as incorporated alkoxyglycol (compound (E) with x=2, z=3, R 11 and R 12 Each is a C1 to C4 alkyl group). This is referred to herein as Component 1.

[0160] The following formulations were prepared and their properties were determined as follows:

[0161] Dry boiling point (ERBP) according to ASTM D1120

[0162] Wet boiling point (WERBP) according to SAE J1703

[0163] Kinematic viscosity according to ASTM D445 at -40°C unless otherwise stated

[0164] Example 1

[0165]

[0166] MTG: triethylene glycol monomethyl ether (compound (A), n=3)

[0167] BTG: triethylene glycol monobutyl ether (compound (B), m = 3, R1 = n-butyl)

[0168] MTG-Borate: MTG borate ester (B(MTG)3)

[0169] It can be seen that the pure silicone ester has slightly higher ERBP and WERBP values, but significantly higher low temperature viscosity compared to the pure borate ester (entry 1 vs. 4).

[0170] When mixed with alkyl glycol ethers, silicone ester-based blends maintain their advantages in ERBP and WERBP and even extend them further, where the viscosity can be reduced to almost the same level as that of borate-based blends (entries 2 vs. 5 and 3 vs. 6).

[0171] Example 2

[0172] A formulation with the following composition (wt %) was prepared:

[0173]

[0174] BTG: triethylene glycol mono-n-butyl ether (compound (B), m=3, R 1 =n-butyl)

[0175] MTG: triethylene glycol monomethyl ether (compound (A), n=3)

[0176] MteG: Tetraethylene glycol monomethyl ether (compound (A), n=4)

[0177] DEG: diethylene glycol (compound (C), k = 2)

[0178] Additive mixture: 2.5% corrosion inhibitor, 2.5% and 10.0% lubricant as described in WO 2015 / 052234, composition FFC4, 0.25% anionic wetting aid, 1.5% amine antioxidant as heat stabilizer, dissolved in 83.25% MTG

[0179] In addition, Examples 3, 4, 6 and 8 given in Research Publication 694049 published on January 17, 2022 were adjusted and their performance at -40°C [mm 2 / s], ERBP [°C] and WERBP [°C] are as shown in Example 2:

[0180]

[0181] Comparative example RD3 has similar component 1 and MTG content as inventive example 2, but contains 24 wt% BTG, whereas in inventive example 2 the BTG content is only 10 wt%, but it also has a 10 wt% MTeG content.

[0182] This results in approximately comparable results for viscosity and dry boiling point (ERBP) at -40°C, but a wet boiling point (WERBP) of Example 2 according to the invention that is 13°C higher than that of Comparative Example RD3.

[0183] Thus, MTeG as component (A) according to the invention with n=4 shows a more favorable influence on the wet boiling point than an increase in the content of triethylene glycol mono-n-butyl ether (BTG), while maintaining good values ​​for viscosity and dry boiling point.

[0184] Comparative example RD8 has similar component 1 and MTG content as example 3 according to the invention, but contains only 2 wt% BTG, whereas in example 2 according to the invention the BTG content is 10 wt%.

[0185] This results in approximately comparable results for viscosity and dry boiling point (ERBP) at -40°C, but a wet boiling point (WERBP) of Example 3 according to the invention that is 4°C higher than that of Comparative Example RD8.

[0186] Therefore, BTG (component (B), m = 3, R 1 An increase in the (butyl) content shows a favourable effect on the wet boiling point, while maintaining good values ​​for viscosity and dry boiling point.

Claims

1. A functional liquid having a viscosity not exceeding 750 cSt (mm2) at -40°C according to FMVSS116. 2 / s), including: (A) at least one alkoxy glycol according to formula (I) H3C-O-[-CH2-CH2-O-] n -H in, n is an integer from 2 to 5, and For at least 30% by weight of all components of formula (I), n=3, (B) at least one alkoxy glycol according to formula (II) R 1 -O-[-CH2-CH2-O-] m -H in, R 1 is a C2 to C4 alkyl group, m is an integer from 2 to 6, and For at least 65% by weight of all components of formula (II), m=3, (C) optionally at least one ethylene glycol, according to formula (III) HO-[-CH2-CH2-O-] k -H in, k is an integer at least 2, and For at least 80% by weight of all components of formula (III), k=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 organosilicon compound according to formula (IV) R 11 x -Si(-[-O-CH2-CH2-] z -OR 12 ) 4-x in, x is a positive integer 1, 2 or 3, preferably 2, z is an integer from 2 to 4, R 11 is C1 to C4 alkyl, in particular methyl or ethyl, particularly preferably methyl, and R 12 is C1 to C4 alkyl, in particular methyl or n-butyl, particularly preferably methyl, in, The proportion of (E) is 40% to 55% by weight, preferably 43% to 55% by weight, particularly preferably 45% to 53% by weight, very particularly preferably 47% to 52% by weight, The proportion of (A) is 24 wt % to 45 wt %, The proportion of (B) is 5 to 20% by weight, preferably 7 to 15% by weight, The proportion of (C) is 0% to 10% by weight, preferably 0% to 5% by weight, (D) has a ratio of more than 0% by weight to 5% by weight, Provided that the sum of all components (A) to (E) is always equal to 100% by weight, It is characterized in that, among components (A) to (C) and (E), - the sum of all alkoxy glycols or glycols with n, m, k and z = 2 is greater than 0 (zero) mol % and not greater than 10 mol %, - the sum of all alkoxy glycols or glycols with n, m, k and z = 3 is at least 60 mol %, and - the sum of all alkoxy glycols or glycols with n, m, k and z=4 is greater than 0 mol % to 20 mol %, and - The ratio of boric acid ester to alkoxyglycol or ethylene glycol does not exceed 3% by weight.

2. The composition according to claim 1, characterized in that Component (A) is mainly composed of triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether.

3. The 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% by weight, very particularly preferably at least 90% by weight and in particular at least 95% by weight.

4. A composition according to any one of the preceding claims, characterized in that Component (B) is selected from triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether.

5. A composition according to any one of the preceding claims, characterized in that Component (C) is selected from diethylene glycol and triethylene glycol.

6. A composition according to any one of the preceding claims, characterized in that Component (D) comprises at least one compound selected from alkylamine ethoxylates, alkanolamines, heterocyclic nitrogen-containing organic compounds, and alkoxylates of ricinoleic acid, castor oil, or any other ricinoleic acid esters.

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

8. A composition according to any one of the preceding claims, characterized in that R in component (E) 11 It's methyl.

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

10. A composition according to any one of the preceding claims, characterised in that R in component (E) 12 It's methyl.

11. A composition according to any one of the preceding claims, characterized in that Substructure H-[-O-CH2-CH2-] in component (E) z -OR 12 The alkylene glycol monoalkyl ether is the same as that used as component (A) and / or (B), and the alkylene glycol monoalkyl ether is particularly preferably the same as that used as component (A).

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

13. The reaction mixture according to claim 12, comprising at least one diethylene glycol (C) and at least one polynuclear silicon compound, such as dinuclear and trinuclear, preferably dinuclear silicon compound.

14. The reaction mixture according to claim 13, characterized in that The polynuclear silicon compound is selected from R 11 x -Si(-[-O-CH2-CH2-] z -O-R 12 ) 4-x-1 -(-O-[-CH2-CH2-O-] k -)-Si R 11 x (-[-O-CH2-CH2-] z -O-R 12 ) 4-x-1 and R 11 x -Si(-[-O-CH2-CH2-] z -OR 12 ) 4-x-1 -(-O-[-CH2-CH2-O-] k -)-Yes R 11 x (-[-O-CH2-CH2-] z -OR 12 ) 4-x-2 -(-O-[-CH2-CH2-O-] k -)-Yes R 11 x (-[-O-CH2-CH2-] z -OR 12 ) 4-x-1 , wherein the variables are as defined in any one of the preceding claims and x is at least 2.

15. Use of the composition and reaction mixture according to any of the preceding claims as functional fluid, preferably as hydraulic fluid or brake fluid.

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