Biodegradable hydraulic fluids based on linear and branched carboxylic acid complex esters

Abstract

The present invention relates to a method for operating a hydraulic system, comprising pressurizing a hydraulic fluid within the hydraulic system, wherein the hydraulic fluid is a polyol selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol and dipentaerythritol; and an aliphatic C3-C3 compound. 12 Diacids selected from dicarboxylic acids;- Linear aliphatic C6~C 22 Linear monoacids selected from monocarboxylic acids; as well as branched aliphatic C6-C6 acids. 12 The present invention relates to a method comprising a complex ester that can be obtained by reacting a branched monoacid selected from monocarboxylic acids. The present invention also relates to hydraulic fluids.

Description

[Technical Field]

[0001] The present invention relates to a method for operating a hydraulic system, which includes pressurizing the hydraulic fluid within the hydraulic system, wherein the hydraulic fluid is - Polyols selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol, and dipentaerythritol; - Aliphatic C3~C 12 Diacids selected from dicarboxylic acids; - Straight chain aliphatic C6~C 22 Linear monoacids selected from monocarboxylic acids; and - Branched aliphatic C6~C 12 Branched monoacids selected from monocarboxylic acids The present invention relates to a method comprising a complex ester that can be obtained by reacting [a certain substance].

[0002] The present invention also relates to hydraulic fluid. Combinations of preferred embodiments and other preferred embodiments are within the scope of the present invention. [Background technology]

[0003] There are many known hydraulic fluids for use in hydraulic systems that typically have mechanical elements driven by pressurized hydraulic fluid. Specific requirements for these hydraulic fluids vary depending on the application, but typically include requirements for sufficient fluid stability, low viscosity at low temperatures, high viscosity index, and low friction.

[0004] Furthermore, minimizing the environmental impact of hydraulic fluids when they are disposed of or discharged from hydraulic systems is becoming increasingly important. This is especially true in offshore oil and gas drilling, onboard hydraulic applications, and other production activities where discharged hydraulic fluids may enter the environment. [Overview of the Initiative] Problem to be Solved by the Invention

[0005] Numerous drawbacks associated with many known hydraulic fluids, especially environmental drawbacks, result from the use of oils therein, particularly mineral oils or synthetic hydrocarbon oils. It would be advantageous to provide a hydraulic fluid that comprises environmentally compatible components and does not rely on mineral oil or synthetic hydrocarbon oil formulations to function effectively.

[0006] The object was to overcome these drawbacks, and in particular to find an environmentally compatible biodegradable hydraulic fluid having excellent low-temperature properties and a high viscosity index. Means for Solving the Problem

[0007] This object is achieved by a method for operating a hydraulic system, comprising pressurizing a hydraulic fluid in the hydraulic system, wherein the hydraulic fluid is a polyol selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol and dipentaerythritol; - an aliphatic C3~C 12 dicarboxylic acid selected from dicarboxylic acids; - linear aliphatic C6~C 22 linear monoacid selected from monocarboxylic acids; and - branched aliphatic C6~C 12 branched monoacid selected from monocarboxylic acids The problem has been solved by a method comprising a complex ester obtainable by reacting the above components.

[0008] This object is also achieved, wherein the hydraulic fluid is - a polyol selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol and dipentaerythritol; - a diacid selected from aliphatic C3 to C 12 dicarboxylic acids; - a linear monoacid selected from linear aliphatic C6 to C 22 monocarboxylic acids; and - a branched monoacid selected from branched aliphatic C6 to C 12 monocarboxylic acids The problem is also solved by the hydraulic fluid according to any one of the preceding claims, which comprises a composite ester obtainable by reacting the above components. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [Figure 1] This figure is a result obtained when measuring the traction coefficient ("T.C.") while varying the slide-roll ratio ("SRR") from 0% to 50%. MODE FOR CARRYING OUT THE INVENTION

[0010] Typically, a hydraulic system comprises: - a pump for pressurizing the hydraulic fluid, - a control unit for controlling the hydraulic pressure, flow direction or flow rate of the pumped hydraulic fluid; and - a conversion unit for converting the controlled hydraulic pressure of the hydraulic fluid into mechanical power .

[0011] The pump is driven, for example, by an electric motor, and generates hydraulic pressure by pumping hydraulic fluid from a first oil tank. The pump can be a hydraulic pump such as a hydraulic gear pump, hydraulic screw pump, hydraulic vane pump, or hydraulic plunger pump. The pressure of the hydraulic fluid generated by the pump is, for example, 5 to 50 MPa.

[0012] The control unit includes, for example, a pressure control valve for controlling hydraulic pressure, a directional control valve for controlling the flow direction, or a flow control valve for controlling the flow rate. The pressure control valve, for example, adjusts the pressure of the hydraulic fluid generated by the pump and allows a portion of the hydraulic fluid to be released to a second oil tank when the pressure measured by the pressure gauge exceeds a certain value. The pressure control valve may be a relief valve, a pressure reducing valve, an unloader valve, a sequence valve, or a counterbalance valve. The directional control valve consists of, for example, an electromagnetic switching valve and a check valve. The flow control valve may be, for example, a throttle valve or a flow control valve. Deceleration valves may be incorporated into these valves.

[0013] The conversion unit converts hydraulic pressure into power, typically according to a flow rate controlled by, for example, a flow control valve. The conversion unit may include a hydraulic cylinder, a hydraulic motor, etc. The moving speed of the hydraulic cylinder, hydraulic motor, etc., may be adjustable through the control of the hydraulic fluid flow rate by the flow control valve. Hydraulic cylinders may be single-acting, double-acting, or special types. Hydraulic motors may be gear motors, vane motors, plunger motors, etc.

[0014] The hydraulic fluid can be pressurized to, for example, 5 to 50 MPa.

[0015] Composite esters include polyols, diacids, linear monoacids, and Branched monoacids can be obtained by reacting them, for example, by an esterification reaction catalyzed by an esterification catalyst.

[0016] Esterification is typically carried out in a temperature range of 50–250°C. The water formed during esterification can be removed by common methods, such as distillation.

[0017] The esterification catalyst may be an inorganic acid (such as sulfuric acid or phosphoric acid), an organic sulfonic acid (such as methanesulfonic acid and p-toluenesulfonic acid), or an amphoteric catalyst (such as a tetraalkoxytitanium compound, e.g., a compound of titanium, tin(II), tin(IV), or zirconium, such as tetrabutoxytitanium, tin(II) oxalate, and tin(IV) oxide). When the esterification catalyst is selected from organic or inorganic acids, the esterification is preferably carried out in a temperature range of 50 to 160°C. When the esterification catalyst is selected from amphoteric catalysts, the esterification is preferably carried out in a temperature range of 100 to 250°C, more preferably 120 to 200°C.

[0018] The esterification catalyst can be used in an effective amount typically ranging from 0.05 to 10% by weight, more preferably from 0.1 to 5.0% by weight, based on the combined amount of the acid component and the alcohol component.

[0019] The polyols are selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol, and dipentaerythritol. Mixtures of polyols are possible.

[0020] The polyol is preferably selected from neopentyl glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol. The polyol is particularly selected from neopentyl glycol and trimethylolpropane. In a preferred embodiment, the polyol is neopentyl glycol. In another preferred embodiment, the polyol is trimethylolpropane.

[0021] Diacids include aliphatic C3-C3 acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, or dodenaedioic acid. 12 Selected from dicarboxylic acids. A mixture of diacids is possible.

[0022] The diacid is preferably selected from adipic acids.

[0023] Linear monoacids are linear aliphatic C6-C6 acids. 22 Selected from monocarboxylic acids. Linear monoacids are preferably linear aliphatic C8-C8. 18 Selected from monocarboxylic acids. In another preferred form, the linear monoacid is a linear aliphatic C. 10 ~C 16 Selected from monocarboxylic acids.

[0024] Examples of linear monoacids include pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, nonadecanoic acid, and eicosanoic acid.

[0025] A prime example of a linear monoacid is lauric acid.

[0026] Branched aliphatic C6~C 12 Branched monoacids selected from monocarboxylic acids. Mixtures of branched monoacids are also possible. Examples of branched monoacids include isohexanoic acid, isoheptanoic acid, isooctanoic acid, 2-ethylhexanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, and isodecanoic acid.

[0027] The branched monoacid is preferably selected from branched aliphatic C8-C9 monocarboxylic acids such as isooctanoic acid, 2-ethylhexanoic acid, isononanoic acid, and 3,5,5-trimethylhexanoic acid. The branched monoacid is particularly selected from 3,5,5-trimethylhexanoic acid.

[0028] 3,5,5-trimethylhexanoic acid is often the main component of isononanoic acid. As used herein, isononanoic acid refers to one or more branched-chain aliphatic carboxylic acids having nine carbon atoms. Examples of isononanoic acid include 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid, and combinations thereof. In preferred embodiments, the isononanoic acid contains more than 90% of one of the following as its main component: 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, and 2,2,4,4-tetramethylpentanoic acid. The remainder of the isononanoic acid may include other carboxylic acid isomers having 9 carbon atoms and small amounts of one or more impurities. In another preferred embodiment, the isononanoic acid has 3,5,5-trimethylhexanoic acid as the main component, more than 90%, and more preferably, the main component is 3,5,5-trimethylhexanoic acid, more than 95%.

[0029] The molar ratio of branched monoacids to straight-chain monoacids can be 3.5:1 to 1:1.5, preferably 2.7:1 to 1.3:1, and particularly 2.2:1 to 1.6:1.

[0030] The composite ester may contain at least 10 mol%, preferably at least 15 mol%, and particularly at least 20 mol%, of a polyol, such as neopentyl glycol or trimethylolpropane.

[0031] The composite ester may contain up to 60 mol%, preferably up to 55 mol%, and especially up to 50 mol%, of a polyol, such as neopentyl glycol or trimethylolpropane.

[0032] The composite ester may contain 10 to 60 mol%, preferably 15 to 50 mol%, and particularly 20 to 45 mol%, of a polyol, such as neopentyl glycol or trimethylolpropane.

[0033] The amounts of the components of a complex ester (e.g., polyols, diacids, linear monoacids, and branched monoacids) usually refer to the amounts reacted to obtain the complex ester in an esterification reaction, which can be catalyzed, for example, by an esterification catalyst.

[0034] The composite ester may contain at least 0.2 mol%, preferably at least 0.5 mol%, and particularly at least 1.0 mol%, of a diacid, such as adipic acid.

[0035] The composite ester may contain up to 27 mol%, preferably up to 35 mol%, and especially up to 40 mol%, of a diacid, such as adipic acid.

[0036] The composite ester may contain 0.2 to 40 mol%, preferably 0.5 to 35 mol%, and particularly 1.0 to 28 mol%, of a diacid, such as adipic acid.

[0037] The composite ester contains at least 3 mol%, preferably at least 6 mol%, and especially at least 9 mol%, of a linear monoacid, such as a linear aliphatic C8-C8 acid. 18 It may contain monocarboxylic acids.

[0038] The composite ester contains up to 45 mol%, preferably up to 35 mol%, and especially up to 30 mol%, of linear monoacids, such as linear aliphatic C8-C8. 18 It may contain monocarboxylic acids.

[0039] The complex ester may contain 3 to 45 mol%, preferably 6 to 35 mol%, and particularly 9 to 30 mol%, of a linear monoacid, such as lauric acid.

[0040] The composite ester may contain at least 10 mol%, preferably at least 15 mol%, and especially at least 20 mol%, of a branched monoacid, such as a branched aliphatic C8-C9 monocarboxylic acid.

[0041] The complex ester may contain up to 65 mol%, preferably up to 60 mol%, and especially up to 55 mol%, of branched monoacids, such as branched aliphatic C8-C9 monocarboxylic acids.

[0042] The complex ester may contain 10 to 65 mol%, preferably 15 to 60 mol%, and especially 20 to 55 mol%, of a branched monoacid, such as 3,5,5-trimethylhexanoic acid.

[0043] Composite esters are - 10-60 mol% polyol, e.g., neopentyl glycol, trimethylolpropane, pentaerythritol, or dipentaerythritol; - 0.2 to 40 mol% of diacids, such as adipic acid; - 3-45 mol% linear monoacids, e.g., linear aliphatic C8-C18 monocarboxylic acids; and - May contain 10-65 mol% of branched monoacids, such as branched aliphatic C8-C9 monocarboxylic acids; The total weight of the components is 100%.

[0044] Composite esters are - 15-50 mol% polyol, e.g., neopentyl glycol, trimethylolpropane, pentaerythritol, or dipentaerythritol; - 0.5 to 35 mol% of diacids, such as adipic acid; - 6-35 mol% linear monoacids, e.g., linear aliphatic C8-C18 monocarboxylic acids; and - May contain 15-60 mol% of branched monoacids, such as branched aliphatic C8-C9 monocarboxylic acids; The total weight of the components is 100%.

[0045] Composite esters are - 20-45 mol% polyol, e.g., neopentyl glycol or trimethylolpropane; - 1.0 to 28 mol% of diacids, such as adipic acid; - 9-30 mol% of linear monoacids, such as lauric acid; and - May contain 20-55 mol% of branched monoacids, such as 3,5,5-trimethylhexanoic acid; and The total weight of the components is 100%.

[0046] The hydraulic fluid may contain at least 5% by weight, 10% by weight, 20% by weight, 25% by weight, 30% by weight, 40% by weight, 50% by weight, 70% by weight, 80% by weight, 90% by weight, 95% by weight, 98% by weight, or 99% by weight of the composite ester. Preferably, the hydraulic fluid contains at least 20% by weight of the composite ester. In another preferred embodiment, the hydraulic fluid contains at least 95% by weight of the composite ester. The hydraulic fluid may contain up to 100% by weight, 99% by weight, 95% by weight, or 90% by weight of the composite ester.

[0047] Hydraulic fluids typically contain additives in addition to composite esters. Suitable additives may be selected from viscosity index improvers, polymer thickeners, corrosion inhibitors, cleaning agents, dispersants, defoamers, dyes, anti-wear additives, extreme pressure additives, anti-wear additives, friction modifiers, metal deactivators, and pour point depressants.

[0048] Preferred additives for hydraulic fluids include pour point depressants, viscosity index improvers, defoamers, antioxidants, rust and corrosion inhibitors, and wear-resistant compounds.

[0049] The total amount of additives in the hydraulic fluid may range from 0 to 25% by weight, or 0.01 to 20% by weight, or 0.1 to 15% by weight, or 0.5 to 10% by weight, or 1 to 5% by weight of the hydraulic fluid.

[0050] Viscosity index improvers include high molecular weight polymers that increase the relative viscosity of oil at high temperatures compared to its relative viscosity at low temperatures. Examples of viscosity index improvers include polyacrylates, polymethacrylates, alkyl methacrylates, vinylpyrrolidone / methacrylate copolymers, polyvinylpyrrolidone, polybutene, olefin copolymers, such as ethylene-propylene copolymer or styrene-butadiene copolymer, or polyalkenes, such as PIB, styrene / acrylate copolymer, and polyethers, as well as combinations thereof. The most common viscosity index improvers are methacrylate polymers and copolymers, acrylate polymers, olefin polymers and copolymers, and styrene-butadiene copolymer. Other examples of viscosity index improvers include polymethacrylates, polyisobutylene, alpha-olefin polymers, alpha-olefin copolymers (e.g., ethylene-propylene copolymer), polyalkylstyrene, phenol condensates, naphthalene condensates, and styrene-butadiene copolymer. Of these, polymethacrylates having a number average molecular weight of 10,000 to 300,000 and alpha-olefin polymers or alpha-olefin copolymers having a number average molecular weight of 1,000 to 30,000, particularly ethylene-alpha-olefin copolymers having a number average molecular weight of 1,000 to 10,000, are preferred. Viscosity index increasers can be added and used, either alone or in mixtures, in amounts conveniently ranging from ≥0.05% to ≤20.0% by weight relative to the weight of the base stock.

[0051] Suitable polymeric thickeners include, but are not limited to, polyisobutene (PIB), oligomer copolymer (OCP), polymethacrylate (PMA), styrene-butadiene copolymer, or high-viscosity esters (compound esters).

[0052] Examples of corrosion inhibitors include various oxygen-containing materials, nitrogen-containing materials, sulfur-containing materials, and phosphorus-containing materials, as well as metal-containing compounds (salts, organometallics, etc.) and non-metal-containing or ashless materials. Examples of corrosion inhibitors include hydrocarbyl-, aryl-, alkyl-, arylalkyl-, and alkylaryl-type cleaning agents (neutral, overbasic), sulfonates, phenates, salicylates, alcoholates, carboxylates, salixalates, phosphates, phosphates, thiophosphates, amines, amine salts, amine phosphates, amine sulfonates, alkoxylated amines, etheramines, polyetheramines, amides, imides, azoles, diazoles, triazoles, benzotriazoles, and benzothiadols. Examples of additive types include, but are not limited to, oles, mercaptobenzothiazole, toltriazole (TTZ type), heterocyclic amines, heterocyclic sulfides, thiazoles, thiadiazoles, mercaptothiadiazoles, dimercaptothiadiazoles (DMTD type), imidazoles, benzimidazoles, dithiobenzimidazoles, imidazolines, oxazolines, Mannich reaction products, glycidyl ethers, anhydrides, carbamates, thiocarbamates, dithiocarbamates, polyglycols, or mixtures thereof.

[0053] Cleaning agents include those that adhere to dirt particles and prevent them from adhering to the critical surface. Cleaning agents can also adhere to the metal surface itself, keeping it clean and preventing corrosion. Cleaning agents include alkyl salicylate calcium, alkyl phenate calcium, and alkali sulfonate calcium, and alternative metal ions such as magnesium, barium, or sodium are used. Examples of usable cleaning agents and dispersants include metal-based cleaning agents such as neutral and basic alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates, alkenyl succinimides and alkenyl succinimide esters and their borohydrides, phenates, and salienius complex cleaning agents, and ashless dispersants modified with sulfur compounds. These agents may be added and used individually or in mixtures, preferably in amounts ranging from ≥0.01% to ≤1.0% by weight relative to the weight of the base stock, and may also be high total base number (TBN), low TBN, or high / low TBN mixtures.

[0054] Dispersants are additives that help prevent the formation of sludge, varnish, and other deposits on critical surfaces. Dispersants can be succinimide dispersants (e.g., N-substituted long-chain alkenyl succinimides), Mannich dispersants, ester-containing dispersants, condensation products of fatty hydrocarbyl monocarboxylic acid acylating agents with amines or ammonia, alkylaminophenol dispersants, hydrocarbyl-amine dispersants, polyether dispersants, or polyetheramine dispersants. In one embodiment, the succinimide dispersant comprises a polyisobutylene-substituted succinimide, and the polyisobutylene from which the dispersant is derived may have a number average molecular weight of about 400 to about 5000 or about 950 to about 1600. In one embodiment, the dispersant comprises a borate dispersant. Typically, the borate dispersant comprises a succinimide dispersant comprising a polyisobutylene succinimide, and the polyisobutylene from which the dispersant is derived may have a number average molecular weight of about 400 to about 5000. The borate dispersant is described in more detail in the section on extreme pressure agents mentioned above.

[0055] The defoaming agent may be selected from silicones, polyacrylates, and the like. The amount of defoaming agent in the compositions described herein may range from ≥0.001% by weight to ≤0.1% by weight based on the total weight of the formulation. As a further example, the defoaming agent may be present in an amount of about 0.004% by weight to about 0.008% by weight.

[0056] A suitable extreme pressure additive is a sulfur-containing compound. In one embodiment, the sulfur-containing compound may be a sulfurized olefin, a polysulfide, or a mixture thereof. Examples of sulfurized olefins include sulfurized olefins derived from propylene, isobutylene, and pentene; organic sulfides and / or polysulfides, including benzyl disulfide; bis-(chlorobenzyl) disulfide; dibutyl tetrasulfide; di-tert-butyl polysulfide; and methyl sulfide esters of oleic acid, alkylphenol sulfide, dipentene sulfide, terpene sulfide, Diels-Alder sulfide adducts, alkylsulfphenyl N'N dialkyldithiocarbamates; or mixtures thereof. In one embodiment, the sulfurized olefin includes sulfurized olefins derived from propylene, isobutylene, pentene, or mixtures thereof. In one embodiment, the sulfur-containing compound of the extreme pressure additive includes dimercaptothiadiazole or its derivatives or mixtures thereof. Examples of dimercaptothiadiazoles include compounds such as 2,5-dimercapto-1,3,4-thiadiazole or hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole or their oligomers. Oligomers of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole are typically formed by forming sulfur-sulfur bonds between 2,5-dimercapto-1,3,4-thiadiazole units to form two or more derivatives or oligomers of the thiadiazole units. Suitable 2,5-dimercapto-1,3,4-thiadiazole derivatives include, for example, 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or 2-tert-nonyldithio-5-mercapto-1,3,4-thiadiazole. The number of carbon atoms in the hydrocarbyl substituent of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically ranges from 1 to 30, or 2 to 20, or 3 to 16. Examples of extreme pressure additives include compounds containing boron and / or sulfur and / or phosphorus. The extreme pressure additive may be present in the composition at a concentration of 0% to about 20% by weight, or about 0.05% to about 10.0% by weight, or about 0.1% to about 8% by weight.

[0057] Examples of wear-resistant additives include organic borates, organic phosphites such as didodecyl phosphite, organic sulfur-containing compounds such as sperm whale oil or sulfur terpenes, zinc dialkyldithiophosphates, zinc diaryldithiophosphates, phosphosulfur hydrocarbons, and any combination thereof.

[0058] Examples of friction modifiers include metal-containing compounds or materials, ashless compounds or materials, or mixtures thereof. Examples of metal-containing friction modifiers include metal salts or metal ligand complexes, where the metal can be an alkali metal, an alkaline earth metal, or a transition metal. Such metal-containing friction modifiers may also have low ash properties. Examples of transition metals include Mo, Sb, Sn, Fe, Cu, and Zn. Examples of ligands include alcohols, polyols, glycerols, partially ester glycerols, thiols, carboxylates, carbamates, thiocarbamates, dithiocarbamates, phosphates, thiophosphates, dithiophosphates, amides, imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles, triazoles, and hydrocarbyl derivatives of other polar molecular functional groups containing effective amounts of O, N, S, or P, either alone or in combination. In particular, Mo-containing compounds, such as Mo-dithiocarbamate, Mo(DTC), Mo-dithiophosphate, Mo(DTP), Mo-amine, Mo(Am), Mo-alcolate, and Mo-alcohol-amide, may be especially effective.

[0059] Examples of ashless friction modifiers include materials containing an effective amount of polar groups, such as hydroxyl-containing hydrocarbyl base oils, glycers, partial glycers, and glyceride derivatives. Examples of polar groups in friction modifiers include hydrocarbyl groups containing an effective amount of O, N, S, or P, either individually or in combination. Other friction modifiers that may be particularly effective include, for example, fatty acid salts (both ash-containing and ashless derivatives), fatty alcohols, fatty amides, fatty esters, hydroxyl-containing carboxylates, and equivalent synthetic long-chain hydrocarbyl acids, alcohols, amides, esters, and hydroxycarboxylates. In some cases, fatty organic acids, fatty amines, and sulfurized fatty acids may be used as suitable friction modifiers. Examples of friction modifiers include fatty acid esters and amides, organic molybdenum compounds, molybdenum dialkylthiocarbamates, and molybdenum dialkyldithiophosphates.

[0060] Suitable metal deactivators include benzotriazoles and their derivatives, such as 4- or 5-alkylbenzotriazoles (e.g., triazoles) and their derivatives, 4,5,6,7-tetrahydrobenzotriazole and 5,5'-methylenebisbenzotriazole; Mannich bases of benzotriazoles or triazoles, such as 1-[bis(2-ethylhexyl)aminomethyl)triazole and 1-[bis(2-ethylhexyl)aminomethyl)benzotriazole; and alkoxy-alkylbenzotriazoles, such as 1-(nonyloxymethyl)benzotriazole, 1-(1-butoxyethyl)benzotriazole and 1-(1-cyclohexyloxybutyl)triazole, and combinations thereof. Non-limiting examples of additional metal deactivators include 1,2,4-triazoles and their derivatives, e.g., Mannich bases of 1,2,4-triazoles such as 3-alkyl(or aryl)-1,2,4-triazole and 1-[bis(2-ethylhexyl)aminomethyl1-1,2,4-triazole; alkoxyalkyl 1-1,2,4-triazoles such as 1-(1-butoxyethyl)-1,2,4-triazole; and acylated 3-amino-1,2,4-triazoles, imidazole derivatives, e.g., 4,4'-methylenebis(2-undecyl-5-methylimidazole) and bis[(N-methyl)imidazole-2-yl]carbinol octyl ethers, as well as combinations thereof. Further non-limiting examples of one or more metal deactivators include sulfur-containing heterocyclic compounds, such as 2-mercapto-benzothiazole, 2,5-dimercapto-1,3,4-thia-diazole and its derivatives; and 3,5-bis[di(2-ethylhexyl)aminomethyl]-1,3,4-thiadiazolin-2-one, and combinations thereof. Further non-limiting examples of one or more metal deactivators include amino compounds, such as salicylidenepropylenediamine, salicylami-noguanidine and its salts, and combinations thereof.The amount of one or more metal deactivators in the composition is not particularly limited, but is typically present in amounts of about 0.01 to about 0.1% by weight, about 0.05 to about 0.01% by weight, or about 0.07 to about 0.1% by weight, based on the weight of the composition. Alternatively, one or more metal deactivators may be present in amounts of less than about 0.1% by weight, less than about 0.7% by weight, or less than about 0.5% by weight, based on the weight of the composition.

[0061] Examples of pour point depressants (PPDs) include polymethacrylates, alkylated naphthalene derivatives, and combinations thereof. Commonly used additives, such as alkyl aromatic polymers and polymethacrylates, are also useful for this purpose. Typically, the treatment rate is in the range of ≥0.001% to ≤1.0% by weight relative to the weight of the base stock.

[0062] Examples of deemulsifiers include trialkyl phosphates and various polymers and copolymers of ethylene glycol, ethylene oxide, and propylene oxide, or mixtures thereof.

[0063] Hydraulic fluid can be prepared by contacting a composite ester with an additive, for example, by mixing them.

[0064] The hydraulic fluid has a kinematic viscosity of 1-2000 mmHg at 40°C. 2 It can be / second. The viscosity classification of hydraulic fluids is usually defined by ASTM D2422 (ISO STD 3448), and according to ASTM D2422, it ranges from 2 to 1500 mm. 2 Eighteen viscosity grades (ISO VG) are specified in the range of / second.

[0065] Hydraulic fluid typically contains less than 5% by weight, less than 3% by weight, less than 1% by weight, or less than 0.5% by weight of water. Preferably, the hydraulic fluid typically contains less than 1% by weight of water. In other forms, the hydraulic fluid may not contain water.

[0066] The hydraulic fluid may contain mineral oils such as naphthenic, paraffinic, or aromatic mineral oils in addition to the composite ester. The hydraulic fluid may contain at least 1% by weight, 5% by weight, or 10% by weight of mineral oil, and up to 70% by weight, 50% by weight, or 30% by weight of mineral oil. In a preferred embodiment, the hydraulic fluid does not contain mineral oil.

[0067] The hydraulic fluid may contain a carboxylic acid ester different from the composite ester, in addition to the composite ester. Preferred carboxylic acid esters are monoesters, diesters, polyesters, a second composite ester, or mixtures thereof. Diesters, polyesters, or a second composite ester are more preferred. The second composite ester is different from the composite ester. The carboxylic acid ester may include a mixture of different carboxylic acid esters.

[0068] Carboxylic acid esters may comprise aliphatic, aromatic, or aliphatic-aromatic alcohols and / or acids. In one form, a carboxylic acid ester consists of an aliphatic alcohol and a fatty acid. In another form, a carboxylic acid ester consists of an aliphatic alcohol and an aliphatic and / or aromatic acid.

[0069] Carboxylic acid esters may comprise saturated, unsaturated, or mixtures of saturated and unsaturated alcohols and / or acids. In one form, carboxylic acid esters may comprise saturated alcohols and saturated acids. In another form, carboxylic acid esters may comprise saturated aliphatic alcohols and saturated fatty acids.

[0070] Suitable carboxylic acid esters are, (i) At least one straight or branched C2-C 24 A monocarboxylic acid is a linear or branched C1-C1 compound. 20 It can be obtained by reacting it with a monoalcohol (also called a "monoester"); or (ii) At least one straight or branched C2-C 20 Dicarboxylic acids are defined as at least one linear or branched C1-C1 type. 20It can be obtained by reacting it with a monoalcohol (also called a "diester"); or (iii) at least one straight or branched C2-C 24 A monocarboxylic acid is a C2-C2 compound having 2 to 10 hydroxyl groups. 20 It can be obtained by reacting with polyols (also called "polyester"); or (iv) At least one type of straight-chain or branched C2-C 24 A monocarboxylic acid and at least one linear or branched C2-C2 compound. 20 A dicarboxylic acid and at least one C2-C2 compound having 2-10 hydroxyl groups. 20 It can be obtained by reacting a mixture containing a polyol (also called a "second complex ester"); or (v) At least one type of straight-chain or branched C2-C 20 Dicarboxylic acid, at least one C2-C2 compound having 2-10 hydroxyl groups. 20 It can be obtained by reacting with a polyol; or (vi) At least one type of straight-chain or branched C2-C 24 A monocarboxylic acid and at least one linear or branched C2-C2 compound. 20 A dicarboxylic acid and at least one linear or branched C1-C15 20 It can be obtained by reacting a mixture containing a monoalcohol; or (vii) At least one type of straight or branched C2-C 24 A monocarboxylic acid and at least one linear or branched C2-C2 compound. 20 A dicarboxylic acid and at least one C2-C2 compound having 2-10 hydroxyl groups. 20 Polyol and at least one C1-C 20 It can be obtained by reacting a mixture containing a monoalcohol.

[0071] In one form, carboxylic acid esters are - At least one linear or branched C5-C selected from the group consisting of pentanoic acid, isopentanoic acid, hexanoic acid, isohexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, isooctanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, nonadecanoic acid, and eicosanoic acid. 20 Monocarboxylic acids, - methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, 1-octanol, 3-methyl-1-butanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, iso-propanol, iso-butanol, 2-octanol, 3-octanol, iso-nonanol, iso-decanol, iso-undecanol, iso-dodecanol, iso-tride-canol, iso-tetradecanol, iso-pentadecanol, iso-hexadecanol, iso-heptadecanol, iso-octadecanol, neo-pentanol, t-butanol, 2-methyl-2-butanol, 2,3-dimethyl-2-butanol, At least one linear or branched C1-C selected from the group consisting of 2-methyl-2-pentanol, 3-methyl-3-pentanol, 3-ethyl-3-pentanol, 2,3-dimethyl-2-pentanol, 2,3-dimethyl-2-pentanol, 2,3-dimethyl(dimehtyl)-2-pentanol, 2,3-dimethyl-3-pentaol, 2,3,4-tri-methyl-3-pentanol, 2-methyl-2-hexanol, and 3-methyl-3-hexanol. 18 It is a monoester that can be obtained by reacting it with a monoalcohol.

[0072] In another form, the monoester is a linear or branched carbon ester. 12 ~C 20Monocarboxylic acids are selected from at least one linear or branched C6-C6 chain. 16 It can be obtained by reacting with a monoalcohol. In another form, the monoester is obtained by reacting with at least one linear or branched carbon. 14 ~C 18 Monocarboxylic acids are selected from at least one linear or branched C6-C6 chain. 12 It can be obtained by reacting with monoalcohols. Examples of monosters include 2-ethylhexyl oleate, 2-ethylhexyl cocoate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, and 2-ethylhexyl taloate.

[0073] In another form, carboxylic acid esters are - At least one linear or branched C3-C3 compound selected from the group consisting of malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, azelaic acid, sebacic acid, brassic acid, docdecanedioic acid, diglycolic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 2,6-decahydro-naphthalenedicarboxylic acid. 12 Dicarboxylic acid, - Pentanol, hexanol, heptanol, iso-pentanol, iso-hexanol, iso-heptanol, 2-ethylhexanol, At least one branched C5-C selected from the group consisting of 2-propylheptanol, 2-propyl-4-methylhexanol, 2-propyl-5-methylhexanol, 2-isopropyl-4-methylhexanol, 2-isopropyl-5-methylhexanol, 2-propyl-4,4-dimethylpentanol, 2-ethyl-2,4-dimethylhexanol, 2-ethyl-2-methylheptanol, 2-ethyl-2,5-dimethylhexanol, 2-isopropylheptanol, 2-butyl-1-octanol, and 2-pentyl-1-nonanol. 14 It is a diester that can be obtained by reacting it with a monoalcohol.

[0074] In one form, the diester contains at least one linear or branched C4-C8 dicarboxylic acid and at least one branched C6-C8 dicarboxylic acid. 16 It can be obtained by reacting with a monoalcohol. In one form, the diester is obtained by reacting at least one linear or branched C6-C8 dicarboxylic acid with at least one branched C6-C8 dicarboxylic acid. 14 These can be obtained by reacting them with monoalcohols. Examples of diesters include diisodecyl adipate, diisotridecyl adipate, di-(isopropylheptyl)-adipate (DPHA), and diisononyl adipate (DNA).

[0075] In another form, carboxylic acid esters are - At least one linear or branched C5-C selected from the group consisting of pentanoic acid, caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, oleic acid, and palmitoleic acid. 18 Monocarboxylic acids and, - At least one linear or branched C3-C3 acid selected from the group consisting of malonic acid, succinic acid, glutaric acid, adipic acid, heptanediic acid, octananedioic acid, nonanediic acid, and decanediic acid. 10 Dicarboxylic acid and, - At least one C2-C2 molecule having 2-10 hydroxyl groups, selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, and dipentaerythritol. 20 This is a second composite ester that can be obtained by reacting a polyol with a mixture containing [a specific compound].

[0076] The hydraulic fluid may contain at least 1% by weight, 5% by weight, or 10% by weight of carboxylic acid esters, and up to 70% by weight, 50% by weight, or 30% by weight of carboxylic acid esters. [Examples]

[0077] TMP: 1,1,1-Trimethylolpropane NPG: Neopentyl Glycol ADA: Adipic acid INA: 3,5,5-trimethylhexanoic acid (commercially available from BASF SE) C12: Lauric acid (99%)

[0078] Example 1 - Preparation of a composite ester Using the amounts of the starting materials shown in Table 1, complex ester A was prepared by the following general method: Adipic acid (6.95 g), trimethylolpropane (105.6 g), 3,5,5-trimethylhexanoic acid (238.2 g), and lauric acid (149.25 g) were packed into a 1-liter three-necked flask. Stannous oxalate (Reaxis® C160, 0.28 wt%) was added to this reaction mixture.

[0079] The mixture was bubbling with nitrogen and heated to 140°C for 3 hours with stirring. The mixture was then heated to 200°C for 5 hours. Vacuum was gradually applied. When the acid value, measured according to ISO 660, reached less than 0.5 mg KOH / g, the residual acid was distilled by applying vacuum at 230°C. The mixture was cooled to 90°C and water was added. The liquid reaction mixture was dried by applying vacuum at 130°C and filtered.

[0080] Accordingly, other esters B to K were prepared using the amounts listed in Table 1.

[0081] Example 2 - Application characteristics of composite esters The application characteristics of composite esters were analyzed and summarized in Table 1.

[0082] The kinematic viscosity at 40°C (KV40) or 100°C (KV100) was determined according to ASTM D 445. The viscosity index (VI) was calculated based on KV40 and KV100, for example, according to ASTM D2270. The pour point (PP) was determined according to ASTM D97.

[0083] [Table 1]

[0084] The data demonstrated that the composite esters in Examples A-G possessed excellent low-temperature properties for hydraulic fluids, as indicated by their low pour points. At the same time, their viscosity indices remained at a high level.

[0085] For comparison, when lauric acid, a linear monoacid, was omitted, the pour point increased and the viscosity index decreased (Examples H, I, and K).

[0086] Example 3 - Reduction of friction The composite esters B and F from the examples, as well as the comparative ester K, were tested using a Mini-Traction Machine (MTM) apparatus in a so-called traction test mode. In this mode, the coefficient of friction is measured at a constant average speed over a range of slide-roll ratios (SRR) to obtain a traction curve. The disc is held in a bath containing the test lubricant so that the contact area between the ball and the flat surface is completely immersed. The ball shaft is aligned with the disc to prevent spin at the contact area, and the slide-roll ratio is independently controlled by driving both the ball and the disc with separate motors. The disc and ball used in the experiment were made of steel (AISI 52100) with a hardness of 750 HV and an Ra of <0.02 μm. The diameters of the disc and ball were 45.0 mm and 19.0 mm, respectively. The traction curve was calculated at 38 Newtons, a speed of 2000 mm / sec, and a temperature of 70°C. The slide-roll ratio ("SRR") was varied from 0 percent to 50 percent, and the traction coefficient ("TC") was measured.

[0087] The resulting figure is shown in Figure 1.

[0088] The solid line represents the data for ester B of the present invention, the dotted line represents the data for ester E of the present invention, and the dashed line represents the data for comparative ester K. This demonstrates the improvement in the frictional properties of the composite ester of the present invention.

[0089] Example 4 - Hydraulic fluid formulation containing a composite ester The hydraulic fluid formulations listed in Table 2 were prepared using composite esters A and C from Table 1, and their properties were analyzed. Thermal oxidation stability "RPVOT" was tested according to ASTM D2272.

[0090] Esters B to G can be formulated using the same method as for hydraulic fluid formulations.

[0091] [Table 2]

[0092] Example 5 - Biodegradable The biodegradability of esters B and F, having the compositions shown in Table 1, was determined according to OECD standard 301B. Both compounds showed biodegradability exceeding 60%.

Claims

1. A method for operating a hydraulic system, comprising pressurizing the hydraulic fluid within the hydraulic system, wherein the hydraulic fluid is - Polyols selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol and dipentaerythritol; - Aliphatic C ３ ~C １２ Diacids selected from dicarboxylic acids; - Linear aliphatic C ６ ~C ２２ Linear monoacids selected from monocarboxylic acids; and - Branched aliphatic C ６ ~C １２ Branched monoacids selected from monocarboxylic acids A method comprising a complex ester that can be obtained by reacting the following.

2. The method according to claim 1, wherein the molar ratio of the branched monoic acid to the linear monoic acid is 3.5:1 to 1:1.5, preferably 2.7:1 to 1.3:1, and particularly 2.2:1 to 1.6:

1.

3. The aforementioned branched monoacid is a branched aliphatic C ８ ~C ９ The method according to claim 1 or 2, selected from monocarboxylic acids.

4. The method according to any one of claims 1 to 3, wherein the branched monoacid is selected from 3,5,5-trimethylhexanoic acid.

5. The method according to any one of claims 1 to 4, wherein the polyol is selected from neopentyl glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol.

6. The method according to any one of claims 1 to 5, wherein the polyol is selected from neopentyl glycol or trimethylolpropane.

7. The method according to any one of claims 1 to 6, wherein the diacid is selected from adipic acid.

8. The monoacid is a linear aliphatic C ８ ~C １８ The method according to any one of claims 1 to 7, which is selected from monocarboxylic acids.

9. The method according to any one of claims 1 to 8, wherein the monoacid is selected from lauric acid.

10. The method according to any one of claims 1 to 9, wherein the composite ester contains 10 to 65 mol%, preferably 15 to 60 mol%, and particularly 20 to 55 mol%, of the branched monoic acid.

11. The aforementioned composite ester, 10 to 60 mol% of the aforementioned polyol; 0.2 to 40 mol% of the diacid; 3 to 45 mol% of the linear monoacid; and It contains 10 to 65 mol% of the branched mono acid; The total weight of the components is 100%. The method according to any one of claims 1 to 10.

12. The aforementioned composite ester, 15 to 50 mol% of the aforementioned polyol; 0.5 to 35 mol% of the diacid; 6 to 35 mol% of the linear monoacid; and It contains 15 to 60 mol% of the branched mono acid; The total weight of the components is 100%. The method according to any one of claims 1 to 10.

13. The method according to any one of claims 1 to 12, wherein the hydraulic fluid contains at least 20% by weight of the composite ester.

14. The aforementioned hydraulic system - A pump for pressurizing the hydraulic fluid, - A control unit for controlling the hydraulic pressure, flow direction, or flow rate of the hydraulic fluid being pumped; and - Conversion unit for converting the controlled hydraulic pressure of the hydraulic fluid into mechanical power. The method according to any one of claims 1 to 13, comprising:

15. The aforementioned hydraulic fluid - Polyols selected from ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylolpropane, trimethylolethane, pentaerythritol and dipentaerythritol; - Aliphatic C ３ ~C １２ The diacid selected from dicarboxylic acids; - Linear aliphatic C ６ ~C ２２ The linear monoacid selected from monocarboxylic acids; and - Branched aliphatic C ６ ~C １２ The branched mono acid selected from monocarboxylic acids A hydraulic fluid according to any one of claims 1 to 14, comprising a composite ester that can be obtained by reacting the following.

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