Water-based hydraulic fluids

Abstract

The present invention relates to water-based hydraulic fluids containing a) phosphonocarboxylic acids or salts thereof of formula (1), wherein R1 is hydrogen or a C1-C4 alkyl group, X is hydrogen, an alkali metal, alkaline earth metal or ammonium group, n is a number from 5 to 7, and the sum (N+n+3), where N is the total number of all carbon atoms in R1, is from 8 to 14, b) at least one water-soluble amine, c) at least one polyol, and d) water, and which have a pH of from 7 to 12.

Description

[0001] Water-based hydraulic fluids

[0002] The present invention relates to water-based hydraulic fluids and additive packages for such hydraulic fluids which contain phosphonocarboxylic acids and have improved application properties.

[0003] Water-based hydraulic fluids are used in a wide variety of applications, especially when hydraulic fluids containing mineral oil leaking from the hydraulic system pose a fire hazard or environmental threat. Typical applications include steel mills, forges, coal mining, gas and oil production facilities, and wind farms. The use of such hydraulic fluids must be combined with a low coefficient of friction and sufficient anti-wear properties to prevent damage to the metal parts used under high loads.

[0004] Due to the reduced lubrication effect of fluids containing mineral oil, carefully balanced additive packages are also used. A water-based hydraulic fluid typically contains the following components:

[0005] (1 ) Water 35 - 70 %

[0006] (2) Freezing point depressants (e.g. glycols) 25 - 50 %

[0007] (3) Viscosity regulator 0 - 20 %

[0008] (3) Lubricant 0 - 20%

[0009] (4) Corrosion inhibitors 0 - 10 %

[0010] (5) pH adjusting agents (e.g. alkanolamines) 0 - 10 %

[0011] (6) Defoamers 0 - 2 %

[0012] (7) Antioxidants 0 - 2%

[0013] (8) Dye 0 - 0.1%

[0014] The pH value is typically alkaline, usually > 9. Raising the pH contributes to corrosion protection. Given the above composition, lubricants are of particular importance.

[0015] DE-A-2534808 describes oxalkylated polyamides made from dicarboxylic acids and oligoamines which have improved lubricating properties and their use in water-based hydraulic fluids.

[0016] US-4138346 discloses phosphoric acid mono- and diesters and sulfur compounds such as mercaptobenzthiazoles, dithiobisthiazoles and alkyl sulfides as lubricants in aqueous hydraulic fluids.

[0017] US-2016 / 0208193 discloses compositions of water-soluble phosphate esters and sulfidic compounds in aqueous hydraulic fluids.

[0018] EP2470627 discloses alkoxylated alkyl phosphoric acid esters as lubricating additives.

[0019] US8563484 discloses an aqueous hydraulic fluid which necessarily uses a first lubricant from the class of phospholipids and a second lubricant from the group of salts of alkoxylates.

[0020] DE102016208486 teaches aqueous compositions containing a) one or more substances selected from the group consisting of sugar amines of the formula (1) wherein

[0021] R 1 CH3 or 2-hydroxyethyl, and b) one or more substances selected from the group consisting of

[0022] Mono-, di-, or tricarboxylic acids with 8-22 carbon atoms and their salts. In addition to the aforementioned requirements for good lubrication performance, there are additional requirements for aqueous hydraulic fluids used today.

[0023] Due to the ingress of salts during use of the fluid, or due to the economic necessity of using hard water or seawater to formulate the fluid, additives must be hard water and electrolyte compatible. Many currently available additives fail to meet one or more of these requirements. For example, many carboxylic acids, and especially phosphoric acid esters, are not stable against water hardness. Furthermore, defoamers are often omitted for economic and ecological reasons, limiting the choice to non-foaming additives. Ethoxylates and other alkoxylates, aliphatic carboxylic acids, especially fatty acids, and aliphatic carboxylic acid alkanolamides are known for their strong foaming effect due to their surfactant structure.Many companies have committed to minimizing the amount of fossil carbon in their products, and therefore prefer to use additives with a low fossil carbon content.

[0024] Last but not least, additives must have good ecotoxicological properties, especially if the hydraulic fluids are used in ecologically sensitive areas such as the North Sea or the Arctic Ocean. For example, every additive in a hydraulic fluid for use in oil production in the North Sea must meet the OSPAR criteria, which require good biodegradation and low toxicity. Many additives do not meet these criteria. For example, imidazolines and mercaptobenzothiazoles are not approved due to their toxicity to marine organisms, so that additives with poorer application properties are often used. Also in the interests of ecological safety and also for economic reasons, the lowest possible additive concentration is desirable. This is often made difficult because additives that achieve a specific effect, e.g. lubrication, often have a negative influence on other properties, e.g.deteriorate corrosion protection.

[0025] A significant improvement therefore lies in components that do not negatively influence the effectiveness profile of other additives. The object of the present invention was therefore to find improved, hard water-stable lubricant additives for water-based hydraulic fluids with good ecotoxicological properties that require only low application concentrations.

[0026] Phosphonocarboxylic acids have been found to possess excellent lubricating properties sufficient for use in hydraulic fluids. They are also non-foaming, stable against hard water and electrolytes, and exhibit excellent biodegradability. This allows the production of hydraulic fluids for known applications, especially for offshore applications in ecologically sensitive areas such as the North Sea, that are ecologically and economically superior to previously known and approved systems.

[0027] The invention thus relates to water-based hydraulic fluids which contain a) phosphonocarboxylic acids or their salts of the formula 1 , wherein

[0028] R 1 represents hydrogen or a C1-C4 alkyl group,

[0029] X is hydrogen, alkali metal, alkaline earth metal or an ammonium group, n is a number from 5 - 7, and the sum (N+n+3), where N is the total number of all carbon atoms in R, is from 8 to 14, b) at least one water-soluble amine c) at least one polyol, and d) water, and which have a pH of 7 to 12. pH values ​​are determined on a 10 wt.% solution of the hydraulic fluid in water with a water hardness of 20° dH.

[0030] Another object of the invention is the use of the compounds of formula 1 as lubricity improvers in water-based hydraulic fluids.

[0031] Another object of the invention is a process for improving the lubricating properties of water-based hydraulic fluids by adding a compound of formula 1 to a hydraulic fluid.

[0032] All percentages in this application are percentages by weight, based on the total weight of the hydraulic fluid as 100% by weight. Exceptions are indicated.

[0033] The hydraulic fluid according to the invention preferably contains 35-70 wt.% water.

[0034] Component a) of the hydraulic fluid is a compound of formula 1 .

[0035] R 1 preferably represents hydrogen, methyl or ethyl, particularly preferably hydrogen or ethyl, most preferably hydrogen.

[0036] In the case of the free acid, X is hydrogen; in the case of salts, it is alkali, alkaline earth, or ammonium ion. The ammonium ions are preferably compounds formed by protonation of the amines described below as neutralizing agents. X preferably represents ammonium ions formed by protonation of alkanolamines. Suitable alkanolamines are described below. n is preferably a number from 4 to 7, particularly preferably 5 to 7, and most preferably 7.

[0037] The sum (N+n+3) results from the total number of carbon atoms in R 1 , which is referred to as N, and n. The sum (N+n+3) is preferably 8 - 12, more preferably 9 - 11, most preferably n is 10.

[0038] The hydraulic fluids according to the invention generally contain 0.1-30% by weight of the compound of formula 1. They preferably contain 0.2-15% by weight or particularly preferably 0.3-10% by weight of the phosphonocarboxylic acid of formula 1. The same amounts apply to the use according to the invention and to the process according to the invention.

[0039] In a preferred embodiment, the water-based hydraulic fluids according to the invention contain a corrosion inhibitor. Suitable corrosion inhibitors are benzenesulfonamidocaproic acid, toluenesulfonamidocaproic acid, benzenesulfon-(N-methyl)amidocaproic acid, toluenesulfon-(N-methyl)amidocaproic acid, alkanoylamidocarboxylic acids, particularly isononanoylamidocaproic acid and triazine-2,4,6-tris(aminohexanoic acid), or the alkali metal, alkaline earth metal, and amine salts of the compounds of formulas 2-4 a) Toluenesulfonamidocaproic acids or benzenesulfonamidocaproic acids (formula 2) with R 2 , R 3 = H or CH3

[0040] Isononanoylamidocaproic acid (Formula 3) c) Triazine-trisaminohexanoic acid (Formula 4)

[0041] Other known and suitable corrosion inhibitors are linear or branched C6 to C8 carboxylic acids such as octanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, n-decanoic acid, n-isodecanoic acid, C4 to C24 dicarboxylic acids such as succinic acid, adipic acid, maleic acid, citric acid, as well as longer-chain dicarboxylic acids such as decanedioic acid, undecanedioic acid, or dodecanedioic acid, whereby the chains can be branched or cyclic, such as 6-carboxy-4-hexyl-2-cyclohexeneoctanoic acid. Furthermore, the salts of the above-listed compounds can also be used.

[0042] If the salts of one of the above-mentioned corrosion inhibitors are used, these are preferably salts that are formed by the reaction of the free acids with a neutralizing agent contained in the hydraulic fluid.

[0043] If corrosion inhibitors are used, the amount of corrosion inhibitor is generally 0.1 - 20 wt.%, preferably 0.5 - 15 wt.% or particularly preferably 0.75 - 10 wt.% corrosion inhibitor.

[0044] If the salts of the corrosion inhibitors are used, the concentrations of the corrosion inhibitors used, stated as weight percentages, are correspondingly higher due to the higher molecular weight of the salts compared to the free acids.

[0045] The hydraulic fluid according to the invention can contain an additional lubricant to reduce friction and abrasion. Suitable lubricants are amine, alkali, or alkaline earth salts of alkyl or aryl phosphoric acid esters and / or amine, alkali, or alkaline earth salts of the phosphoric acid esters of alkoxylated alcohols. Polyalkylene glycols can also be used. Polyalkylene glycols can be obtained by anionic or metal-catalyzed polymerization of alkylene oxides of formula 5 with mono-, di-, tri-, tetra-, and polyfunctional alcohols or amines or mixtures thereof. where R 4 = hydrogen, methyl, ethyl.

[0046] If multiple alkylene oxides are used, polymerization can be carried out sequentially (block arrangement of the monomers) or with a mixture of alkylene oxides (random arrangement of the monomers). Suitable starting alcohols for these polyalkylene glycols include ethylene glycol, propylene glycol, trimethylolpropane, glycerol, pentaerythritol, sorbitol, and other polyhydric alcohols. Suitable amines include the compounds listed below as neutralizing agents, provided they contain acidic NH bonds.

[0047] Other suitable lubricants include sulfur compounds such as mercaptobenzthiazoles, dithiobis(thiazoles), and alkyl disulfides, thiophosphonates, or inorganic compounds such as phosphoric acid or metal sulfides. The arylsulfonic acid amidocarboxylic acids shown in formula (6) also act as lubricants in addition to their properties as corrosion inhibitors.

[0048] In the preferred embodiment of the invention, the hydraulic fluid does not contain any additional lubricant, since the lubricating effect of the phosphonocarboxylic acid is already sufficient.

[0049] The kinematic viscosity at 50 °C of the other lubricants, in particular the polyalkylene glycols thus obtained, can preferably be above 20 mm 2 / s up to below 3000 mm 2 / s, usually the kinematic viscosity ranges from 25 - 2000 mm 2 / s (determined according to ASTM D7042). The hydraulic fluids according to the invention contain a water-soluble amine as component b).

[0050] This amine serves as a neutralizing agent, with which the hydraulic fluid is adjusted to a pH value of 7-12, preferably 8-11, particularly preferably 9-10. An amine is considered water-soluble if it is soluble in demineralized water to a degree of at least 1% by weight, preferably at least 5% by weight, at 20°C.

[0051] Suitable neutralizing agents are water-soluble amines of formula 6

[0052] NR 5 R 6 R 7 (6) wherein

[0053] R 5 , R 6 and R 7 are independently selected from the group consisting of hydrogen;

[0054] hydrocarbon radicals having 1 to 20 C atoms, where the hydrocarbon radical may carry substituents which may include heteroatoms;

[0055] Ce-Ci2 aryl groups or heteroaromatic groups with 5 to 12 ring members, which may carry substituents;

[0056] Remnants of Formula 7

[0057] -(R 8 -O) P -R 9 (7) wherein

[0058] R 8 for an alkylene group with 2 to 6 C atoms,

[0059] R 9 represents hydrogen, a hydrocarbon radical with 1 to 24 C atoms or a group of the formula -NR 10 R 11, p for a number between 2 and 50, and

[0060] R 10 , R 11 independently of one another represent hydrogen, an aliphatic radical having 1 to 24 C atoms, an aryl group or heteroaryl group having 5 to 12 ring members, a poly(oxyalkylene) group having 1 to 50 poly(oxyalkylene) units, wherein the polyoxyalkylene units are derived from alkylene oxide units having 2 to 6 C atoms, or R 10 and R 11 together with the nitrogen atom to which they are bonded, form a ring with 4, 5, 6 or more ring members;

[0061] Remnants of Formula 8

[0062] -[R 12 -N(R 13 )] q -H (8) where

[0063] R 12 represents an alkylene group having 2 to 6 C atoms, each R 13 independently of one another represent hydrogen, an alkyl or hydroxyalkyl radical having up to 24 C atoms, a polyoxyalkylene radical -(R 8 -O)rR 9, or a polyiminoalkylene radical -[R 12 -N(R 14 )2]s, where R 8 , R 9 , and R 12 have the meanings given above, R 14 represents hydrogen, an alkyl or hydroxyalkyl radical having up to 24 C atoms, a polyoxyalkylene radical -(R 8 -O)r- R 9 , and r and s independently represent 1 to 50, and q represents a number from 1 to 20; or R 5 and R 6 together with the nitrogen atom to which they are bonded form a ring; with the proviso that not all radicals R 5 , R 6 and R 7 stand for hydrogen.

[0064] In a first preferred embodiment, R 5 and / or R 6 and / or R 7 independently of each other represent hydrogen or an aliphatic radical, but at least one of R 5 , R 6 and R 7for an aliphatic radical. The aliphatic radical preferably has 1 to 20, particularly preferably 2 to 18 and especially 3 to 6 C atoms.

[0065] The aliphatic radical can be linear, branched, or cyclic. It can also be saturated or unsaturated. The aliphatic radical is preferably saturated.

[0066] The aliphatic radical may bear substituents such as, for example, hydroxyl, C1-C8-alkoxy, cyano, nitrile, nitro, and / or C8-C20-aryl groups, such as, for example, phenyl radicals. If the aliphatic radical bears substituents, these are preferably hydroxyl groups. The C8-C20-aryl groups may, in turn, be optionally substituted with halogen atoms, halogenated alkyl radicals, C1-C20-alkyl, C2-C20-alkenyl, hydroxyl, C1-C8-alkoxy groups, such as, for example, methoxy, amide, cyano, nitrile, and / or nitro groups. If the substituent of the aliphatic radical contains carbon atoms, these carbon atoms are not counted towards the number of carbon atoms in the aliphatic radical.

[0067] In a particularly preferred embodiment, R 5 and / or R 6 and / or R 7independently of one another represent hydrogen, a C1-C8-alkyl, C2-C8-alkenyl, or C3-C6-cycloalkyl radical, and especially an alkyl radical having 1, 2, or 3 C atoms. These radicals can preferably carry up to three substituents. Particularly preferred aliphatic radicals R 5 and / or R 6 and / or R 7 are methyl, ethyl, hydroxyethyl, n-propyl, isopropyl, hydroxypropyl, n-butyl, isobutyl and tert-butyl, hydroxybutyl, n-hexyl, cyclohexyl, n-octyl, n-decyl, n-dodecyl, tridecyl, isotridecyl, tetradecyl, hexadecyl, and octadecyl. If the aliphatic radicals bear substituents, hydroxyl groups are preferred.

[0068] In a further preferred embodiment, R 5 and R 6together with the nitrogen atom to which they are bonded, form a ring. This ring preferably has 4 or more, such as 5, 6, 7 or 8, particularly preferably 5 or 6 ring members. Preferred further ring members are carbon, nitrogen, oxygen and sulfur atoms. The rings can in turn bear substituents such as alkyl radicals. Suitable ring structures are, for example, morpholinyl, pyrrolidinyl, piperidinyl, imidazolyl and azepanyl radicals. In a preferred embodiment, R 7 represents H or an alkyl radical having 1 to 12 carbon atoms.

[0069] In a further preferred embodiment, R 5 , R 6 and / or R 7 independently of one another represent an optionally substituted Ce-Ci2 aryl group or an optionally substituted heteroaromatic group having 5 to 12 ring members.

[0070] In a further preferred embodiment, R5 , R 6 and / or R 7 independently of one another represent an alkyl radical interrupted by heteroatoms. Particularly preferred heteroatoms are oxygen and nitrogen. Thus, R 5 , R 6 and / or R 7 independently preferred for residues of formula 7

[0071] -(R 8 -O) P -R 9 (7) wherein

[0072] R 8 represents an alkylene group having 2 to 6 C atoms and preferably having 2 to 4 C atoms such as ethylene, propylene, butylene or mixtures thereof,

[0073] R 9 represents hydrogen, a hydrocarbon radical with 1 to 24 C atoms or a group of the formula -NR 10 R 11 , p is a number between 2 and 50, preferably between 3 and 25 and in particular between 4 and 10 and

[0074] R 10 , R 11independently of one another represent hydrogen, an aliphatic radical having 1 to 24 C atoms and preferably 2 to 18 C atoms, an aryl group or heteroaryl group having 5 to 12 ring members, a poly(oxyalkylene) group having 1 to 50 poly(oxyalkylene) units, wherein the polyoxyalkylene units are derived from alkylene oxide units having 2 to 6 C atoms, or R 10 and R 11 together with the nitrogen atom to which they are bonded, form a ring with 4, 5, 6 or more ring members.

[0075] Also preferred are R 5 , R 6 and / or R 7 independently for residues of formula 8

[0076] -[R 12 -N(R 13 )] q -H (8) where

[0077] R 12 represents an alkylene group having 2 to 6 C atoms and preferably having 2 to 4 C atoms such as ethylene, propylene or mixtures thereof, each R 13independently of one another represent hydrogen, an alkyl or hydroxyalkyl radical having up to 24 C atoms, a polyoxyalkylene radical -(R 8 -O)rR 9 , or a polyiminoalkylene radical -[R 12 -N(R 14 )2]s, where R 8 , R 9 , and R 12 have the meanings given above, R 14 represents hydrogen, an alkyl or hydroxyalkyl radical having up to 24 C atoms, a polyoxyalkylene radical -(R 8 -O)r- R 9 , and r and s independently of one another are from 1 to 50, and q is a number from 1 to 20 and preferably from 2 to 10, such as three, four, five or six. The radicals of formula 8 preferably contain from 1 to 50, in particular from 2 to 20, nitrogen atoms.

[0078] Particularly preferred water-soluble amines are water-soluble alkylamines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, and longer-chain mono-, di-, and trialkylamines, provided they are at least 1 wt.%, preferably 1-5 wt.%, water-soluble. The alkyl chains can be branched. Also suitable are oligoamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, their higher homologues, and mixtures thereof. Other suitable amines in this series are the alkylated, particularly methylated, representatives of these oligoamines, such as N,N-dimethyldiethyleneamine, N,N-dimethylpropylamine, and longer-chain and / or higher alkylated amines of the same structural principle.Particularly suitable according to the invention are alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, diglycolamine, triglycolamine and higher homologues, methyldiethanolamine, ethyldiethanolamine, propyldiethanolamine, butyldiethanolamine, and longer-chain alkyldiethanolamines, where the alkyl radical may be cyclic and / or branched. Further suitable alkanolamines are dialkylethanolamines such as dimethylethanolamine, diethylethanolamine, dipropylethanolamine, dibutylethanolamine, and longer-chain dialkylethanolamines, where the alkyl radical may also be branched or cyclic. Aminopropanol (isopropanolamine), aminobutanol, aminopentanol, and higher homologues, as well as the corresponding mono- and dimethylpropanolamines and longer-chain mono- and dialkylamino alcohols, can also be used within the meaning of the invention.Last but not least, special amines such as 2-amino-2-methylpropanol (AMP), 2-dimethylamino-2-methyl-1-propanol, 2-aminopropanediol, 2-amino-2-ethylpropanediol, 2-aminobutanediol, and other 2-aminoalkanols, aminoalkylamine alcohols, tris(hydroxymethyl)aminomethane, as well as end-capped representatives such as methylglycolamine, methyldiglycolamine, and higher homologues, di(methylglycol)amine, di(methyldiglycol)amine, and their higher homologues, as well as the corresponding triamines and polyalkyleneglycolamines (e.g., Jeffamine®) are suitable. Mixtures of the above-mentioned amines are typically used to adjust the desired pH values.

[0079] If the desired pH cannot be achieved with the amine alone, other suitable neutralizing agents can be used. These include oxides and hydroxides of alkali and / or alkaline earth metals, such as lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and calcium oxide.

[0080] The neutralizing agents mentioned, especially the amine, are used in amounts required to adjust the hydraulic fluid to a desired pH value. This desired pH value is between 7 and 12, preferably between 8 and 11, particularly preferably between 9 and 10. The amounts of neutralizing agent, especially the amine, required for this purpose are generally between 0.1 and 10 wt.%.

[0081] The hydraulic fluids contain a polyol as component c). Polyols serve as freezing point depressants or viscosity regulators.

[0082] Suitable freezing point depressants comprise 1 to 10 carbon atoms and 1 to 10 OH groups, preferably 1 to 6 carbon atoms and 1 to 6 OH groups, especially 1, 2, 3, or 4 carbon atoms and 1, 2, 3, or 4 OH groups. In any case, they contain no more OH groups than carbon atoms. Examples include ethylene glycol, diethylene glycol, triethylene glycol and higher polyethylene glycols, propylene glycol, dipropylene glycol and higher polypropylene glycols, the corresponding methyl glycols, ethyl, butyl, and other alkyl glycols, and alkylpropylene glycols.

[0083] Glycerol, diglycerol, triglycerol and higher homologues, 1,3-propanediol, and its oligomers and polymers can also be used. Mixtures of these compounds can also be used.

[0084] The concentration of the freezing point depressants used depends on the required freezing point, which can vary greatly depending on the application and area of ​​use.

[0085] 1-50 wt.% freezing point depressants are used, preferably 20-50 wt.%, particularly preferably 30-45 wt.%. Suitable freezing point depressants preferably have a kinematic viscosity of 1 to 20 mm 2 / s at 50 °C (ASTM D 7042).

[0086] Suitable viscosity regulators are polyacrylates, polymethacrylates, and polyalkylene glycols, especially high-molecular-weight polyalkylene glycols. These can be obtained by anionic or metal-catalyzed polymerization of alkylene oxides of formula 5 or their mixtures with mono-, di-, tri-, tetra-, and polyfunctional alcohols or amines. where R 4 = hydrogen, methyl, ethyl.

[0087] If several alkylene oxides are used, the polymerization can be carried out sequentially (block arrangement of the monomers) or with a mixture of oxides (random arrangement of the monomers). Suitable starting alcohols for these polyalkylene glycols are, for example, ethylene glycol, propylene glycol, trimethylolpropane, glycerol, pentaerythritol, sorbitol, and other polyhydric alcohols. Suitable amines are, for example, the compounds listed below as neutralizing agents, provided they contain acidic NH bonds. These polyalkylene glycols are usually not selected according to their molecular weight, but rather according to their kinematic viscosity at 50 °C, which is usually 3000 mm 2 / s up to 50,000 mm 2 / s (ASTM D 7042) and more, depending on the application. The concentration of the viscosity regulator depends on the desired viscosity and can be 1-20%, preferably 5-20%, particularly preferably 10-15%.

[0088] According to the invention, the additives mentioned in the prior art, such as defoamers, dyes, and antioxidants, can also be used in the hydraulic fluid. However, in the preferred embodiment, these can be omitted for the reasons mentioned above.

[0089] The hydraulic fluids according to the invention can be produced by mixing at room temperature or elevated temperatures directly from the components, or by diluting a previously prepared additive package with water, or by diluting a previously prepared additive package with a mixture of water and the freezing point depressant. If the hydraulic fluid is produced directly from the components, it is recommended to initially add the water and, if appropriate, the freezing point depressant and then add the other constituents, preferably adding the neutralizing agents first, followed by the compound of formula 1, and then—if necessary—the other lubricants and additional corrosion inhibitors. Further additives such as defoamers, dyes, antioxidants, and viscosity regulators are added last.If the additive package is manufactured separately, water and the freezing point depressant, if included in the additive package, are added, followed by the neutralizing agent, and then the other components in the order listed above. For high viscosities, especially if the freezing point depressant is not included in the additive package, mixing may require a temperature higher than room temperature. However, this temperature generally does not exceed 80-100°C. For particularly high viscosities, the additive package can be diluted with water.

[0090] Examples

[0091] The application concentrations were selected so that the hydraulic fluids achieve the necessary corrosion protection (no corrosion at 15%

[0092] Application concentration)

[0093] Example 1 (no additives) Reference fluid A

[0094] Water 59.8%

[0095] Monoethylene glycol 40.0%

[0096] Triethanolamine 0.2%

[0097] Example 2 (state of the art) - Hydraulic fluid B

[0098] Water 49.6%

[0099] Monoethylene glycol 40.0%

[0100] Triethanolamine 6.3%

[0101] Monoethanolamine 1.1%

[0102] Toluenesulfone-N-methyl-amidocaproic acid 3.0% Example 3 (state of the art) - Hydraulic fluid C

[0103] Water 49.4%

[0104] Monoethylene glycol 40%

[0105] Triethanolamine 6.5%

[0106] Monoethanolamine 1.1%

[0107] Phosphoric acid butyl ester (mono-diester mixture) 3.0%

[0108] Example 4 - Hydraulic Fluid D

[0109] Water 47.2%

[0110] Monoethylene glycol 40.0%

[0111] Methyldiethanolamine 8.8%

[0112] Isononanoylamidocaproic acid 1.0%

[0113] 10-Phosphonodecanoic acid 3.0%

[0114] Example 5 - Hydraulic Fluid E

[0115] Water 51.7%

[0116] Monoethylene glycol 40%

[0117] Isopropanolamine 5.3%

[0118] 10-Phosphonodecanoic acid 3.0%

[0119] Example 6 - Hydraulic fluid F

[0120] Water 48%

[0121] Monoethylene glycol 40%

[0122] Triethanolamine 6.5%

[0123] Monoethanolamine 1.5%

[0124] Triazine-Trisaminohexanoic acid 1.0%

[0125] 8-Phosphonooctanoic acid 3.0%

[0126] Example 7- Hydraulic fluid G

[0127] Water 47.7%

[0128] Monoethylene glycol 40%

[0129] Cyclohexylamino-N,N-diethanol 7%

[0130] Monoethanolamine 2.3%

[0131] 10-Phosphonododecanoic acid 3.0% The application concentrations were selected so that the hydraulic fluids achieve a minimum corrosion protection, ie no corrosion at a maximum of 15 wt.% of the hydraulic formulation in 20° dH water on cast iron chips (DIN 51360 / 2)

[0132] The inventive formulations DG and the comparative examples AC were subsequently tested for lubricating properties using relevant application-related methods. Lubricating properties were tested using the Reichert abrasion test, the four-ball test (DIN 51350-1), and the Falex test (ASTM D 3223-2) (see Table 1).

[0133] The Reichert test clearly shows reduced abrasion of the DG formulations compared to the standard AC.

[0134] Testing using a four-ball apparatus resulted in the failure of the test due to overload for formulations A (no lubricant additive) and C (water-soluble phosphoric acid ester), while comparative example B (sulfonamidocarboxylic acid) showed significantly higher abrasion than the inventive examples DG based on the phosphonocarboxylic acids.

[0135] The Falex test confirms the previous tests by showing a higher load capacity (lower torque) of the test specimens with the formulations according to ASTM D 3233-B.

[0136] Table 1 : Application properties of the liquids AG

[0137] Explanations for Table 1:

[0138] 1) 20% solution in water, 20 °dH (equivalent to 350 ppm CaCOs), appearance after 24 h, 20°C

[0139] 2) 5% solution in synthetic seawater, appearance after 24 h at 20 °C

[0140] 3)Friction lock scale according to Reichert, parameters: load 15N, rotation distance 100 m, rotation speed 1.6 m / s; material steel rollers, abrasion in [mm 2 ]

[0141] 4) Four-ball test rig - abrasion, parameters; load 300 N, time 1 h, rotation 1450 rpm, DIN 51350-3

[0142] 5) Falex Pin-on-Vee, torque load with 500 Ibs after 30 min

[0143] 6) Limit concentration of the formulation in 20° dH water at which the filter paper remains rust-free. Example C is also not seawater-resistant. The hydraulic formulations of examples D to G, however, demonstrate surprisingly improved lubricating properties and adequate corrosion protection for iron in various application tests.

[0144] Table 2 shows ecotoxicological data for lubricant additives as required by OSPAR for use in the North Sea.

[0145] Table 2 The inventive lubricant compound from Example 3 shows results for biodegradation and algal and fish toxicity that exceed the required limits and generally also show better values ​​than the state of the art (see Comparison 1 and Comparison 2). Comparative Example 2, although it demonstrates improved biodegradability, fails to satisfy the necessary performance tests and is therefore not used.

Claims

Patent claims 1. Hydraulic fluids containing a) phosphonocarboxylic acids or their salts of formula 1 , wherein R 1 represents hydrogen or a C1-C4 alkyl group, X represents hydrogen, alkali metal, alkaline earth metal or an ammonium group, n represents a number from 5 to 7, and the sum (N+n+3), where N is the total number of carbon atoms in R 1 is from 8 to 14, b) at least one water-soluble amine c) at least one polyol, and d) water, and which have a pH of 7 to 12.

2. Hydraulic fluids according to claim 1, which contain 0.1 to 30 wt.% of phosphonocarboxylic acids or their salts of formula 1.

3. Hydraulic fluids according to claim 1 and / or 2, containing 35 - 70 wt.% water.

4. Hydraulic fluids according to one or more of claims 1 to 3, containing 25 - 50 wt.% of a glycol or a polyalkylene glycol or a mixture thereof.

5. Hydraulic fluids according to one or more of claims 1 to 4, wherein formula 1 represents 8-phosphonooctanoic acid, 10-phosphonodecanoic acid or 10-phosphonododecanoic acid.

6. Hydraulic fluids according to one or more of claims 1 to 5, containing at least one corrosion inhibitor selected from the group consisting of a) toluene or benzenesulfonamidocaproic acids of the formula 2 with R 2 , R 3 = H or CH3, Isononanoylamidocaproic acid of formula 3 Triazine-trisaminohexanoic acid of formula 4 aliphatic or aromatic carboxylic acids, aliphatic or aromatic dicarboxylic acids, 7. Hydraulic fluids according to one or more of claims 1 to 6, containing a lubricant for reducing friction and abrasion.

8. Hydraulic fluids according to one or more of claims 1 to 7, wherein the amine of formula 6 NR 5 R 6 R 7 (6) corresponds to where R 5 , R 6 and R 7 are independently selected from the group consisting of hydrogen; hydrocarbon radicals having 1 to 20 C atoms, where the hydrocarbon radical may carry substituents which may include heteroatoms; C6-Ci2 aryl groups or heteroaromatic groups with 5 to 12 ring members, which may carry substituents; Remnants of Formula 7 -(R 8 -O) P -R 9 (7) wherein R 8 for an alkylene group with 2 to 6 C atoms, R 9represents hydrogen, a hydrocarbon radical with 1 to 24 C atoms or a group of the formula -NR 10 R 11 , p for a number between 2 and 50, and R 10 , R 11 independently of one another represent hydrogen, an aliphatic radical having 1 to 24 C atoms, an aryl group or heteroaryl group having 5 to 12 ring members, a poly(oxyalkylene) group having 1 to 50 poly(oxyalkylene) units, wherein the polyoxyalkylene units are derived from alkylene oxide units having 2 to 6 C atoms, or R 10 and R 11 together with the nitrogen atom to which they are attached, form a ring with 4, 5, 6 or more ring members; residues of the formula 8 -[R 12 -N(R 13 )] q -H (8) wherein R 12 represents an alkylene group having 2 to 6 C atoms, each R 13independently of one another represent hydrogen, an alkyl or hydroxyalkyl radical having up to 24 C atoms, a polyoxyalkylene radical -(R 8 -O)rR 9 , or a polyiminoalkylene radical -[R 12 -N(R 14 )2]s, where R 8 , R 9 , and R 12 have the meanings given above, R 14 represents hydrogen, an alkyl or hydroxyalkyl radical having up to 24 C atoms, a polyoxyalkylene radical -(R 8 -O)r- R 9 , and r and s independently represent 1 to 50, and q represents a number from 1 to 20; or R 5 and R 6 together with the nitrogen atom to which they are attached form a ring; with the proviso that not all radicals R 5 , R 6 and R 7 stand for hydrogen.

9. Hydraulic fluids according to one or more of claims 1 to 8, wherein the amine is an alkanolamine, and is preferably selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, diglycolamine, triglycolamine, methyldiethanolamine, ethyldiethanolamine, propyldiethanolamine, butyldiethanolamine, dimethylethanolamine, diethylethanolamine, dipropylethanolamine, dibutylethanolamine and longer-chain dialkylethanolamines, aminopropanol (isopropanolamine), aminobutanol, aminopentanol, mono- and dimethylpropanolamine, 2-amino-2-methylpropanol (AMP), 2-dimethylamino-2-methyl-1-propanol, 2-aminopropanediol, 2-amino-2-ethylpropanediol, and 2-aminobutanediol.

10. Hydraulic fluids according to one or more of claims 1 to 9, containing a thickener selected from the group of polyacrylates, polymethacrylates, polyethylene glycols, polypropylene glycols, polyalkylene glycols. 11 . Use of a) phosphonocarboxylic acids or their salts of formula 1 , wherein R 1 represents hydrogen or a C1-C4 alkyl group, X represents hydrogen, alkali metal, alkaline earth metal or an ammonium group, n represents a number from 5 to 7, and the sum (N+n+3), where N is the total number of carbon atoms in R 1 is from 8 to 14, for improving the lubricating effect of hydraulic fluids which contain b) at least one water-soluble amine c) at least one polyalkylene glycol, and d) water, and which have a pH of 7 to 12.

12. Method for improving the lubricating properties of water-based Hydraulic fluids, by adding a compound of formula 1 to a hydraulic fluid containing b) at least one water-soluble amine c) at least one polyalkylene glycol, and d) water, and which has a pH of 7 to 12 wherein R1 represents hydrogen or a C1-C4 alkyl group, X represents hydrogen, alkali metal, alkaline earth metal or an ammonium group, n is a number from 5 to 7, and the sum (N+n+3), where N is the total number of carbon atoms in R 1 is from 8 to 14.

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