EP0148215B1

EP0148215B1 - Water-based hydraulic fluid

Info

Publication number: EP0148215B1
Application number: EP84902420A
Authority: EP
Inventors: Rosauro V. Holgado
Original assignee: EF Houghton and Co
Current assignee: EF Houghton and Co
Priority date: 1983-06-29
Filing date: 1984-06-08
Publication date: 1991-01-30
Anticipated expiration: 2004-06-08
Also published as: GB2152529A; EP0148215A4; AU555383B1; EP0148215A1; IT1177846B; DE3484057D1; KR910010135B1; BR8406955A; IT8448470A0; JPS60501657A; CA1242431A; JPH0794673B2; GB2152529B; AU3064684A; WO1985000182A1; KR850000516A; GB8503919D0

Abstract

Water-based hydraulic fluid for use in industrial hydraulic systems comprising (1) a polyether-based thickener, (2) a lubricant modifier (3) a dispersant, (4) an EP additive, and (5) water. Preferably, the thickener is a polyether polyol capped with an alpha olefin oxide; the lubricant modifier is a combination of a hydrocarbon oil, a fatty alcohol and a glycol; the dispersant is the reaction product of an alkenyl succinic anhydride and a dialkyl alkanolamine, and the EP additive is a dialkyl dithiophosphate.

Description

This invention relates to an improved high water-based hydraulic fluid particularly suitable for use in industrial hydraulic systems.
The technology of power transmission by means of a hydraulic fluid is well established. Various non- compressible fluids such as water and oil have been used as hydraulic fluids. Petroleum oils have certain advantages over water as hydraulic fluids in that they reduce wear and inhibit rust formation in hydraulic system components such as pumps, and exhibit a higher viscosity than water, thus providing for reduced fluid leakage. Unfortunately, a major deficiency of petroleum oils is flammability. They are also sensitive to the intrusion of water into hydraulic systems in which they are employed. In addition, disposal of spent petroleum oil-based hydraulic fluids presents ecological problems.
In recent years, by reason of their low cost, efforts have been made to provide water-based hydraulic fluids. By reason of the substantially lower viscosity of water-based hydraulic fluids, the inclusion therein of various types of thickener has been suggested. Thus, for example, US-A-4,288,639 discloses polyether-based thickeners for aqueous liquids. It has also been proposed, for example in US-A-4,209,414, to include lubricant modifiers such as alkylene glycols or condensation products of fatty acids and alkanolamines.
It has also been proposed, for example in US―A―4,253,975, to include metal hydrocarbyl dithiophosphates which act as extreme pressure (EP) additives and assist in wear reduction. US―A―4,253,975 discloses, inter alia, a lubricant comprising a dialkyl dithiophosphate, a dispersing agent which is the reaction product of an alkenyl succinic anhydride or acid and an amine to assist in dispersing in dialkyldithiophosphate in water, and a lubricant modifier. Wear loss rates of 5 and 13 mg/hr in a Vickers 104C Pump Test are the best results reported for such compositions.
US-A-4,312,768 discloses water-based hydraulic fluids containing polyether-based thickeners, sulfurized molybdenum or antimony phosphorodithioates, phosphate ester salts and water-soluble polyoxyethylated aliphatic esters. Because of the insolubility of the phosphorodithioates in water they are emulsified prior to use, for example with surfactants such as sodium dodecylbenzene sulfonate, polyoxyethylated fatty alcohol or fatty acid or polyoxyethylated alkylphenol. Wear-loss rates of 17-20 mg/ hour in a Vickers Vane Pump Test are the best results reported for such compositions.
It would be desirable to provide improved water-based hydraulic fluids having wear-loss rates in a standard Vickers Vane Pump Test of significantly less than 5 mg/hour.
This invention relates to thickened, high viscosity, high water-based hydraulic fluids of the oil-in-water emulsion type. By the term "high water-based hydraulic fluids" is meant compositions comprising 80% or more, by weight, of water. In addition to water, the hydraulic fluids of this invention contain as essential constituents (1) a polyether-based thickener, (2) a lubricant modifier, (3) a dispersant, and (4) an EP additive, all in specified proportions. Optionally, the hydraulic fluids of the invention may contain various emulsifiers, corrosion inhibitors, defoamers, coupling agents, metal deactivators, freezing point depressants, and the like, depending upon the particular hydraulic system in which the hydraulic fluid is to be employed. Advantageously, the essential constituents of the hydraulic fluid may be combined to form a concentrate which is readily dilutable with water to provide a hydraulic fluid.
The high water-based hydraulic fluids of this invention provide improvements over prior known aqueous-based hydraulic fluids in the nature of more stable viscosity characteristics, reduced wear and better lubrication.
A high water-based hydraulic fluid according to the present invention can be obtained by blending together at a temperature of 120°-180°F (49°-82°C), the lubricant modifier and dispersing agent, following which, after removal from heat, the EP additive is introduced to the blend. Water is then added and a uniform clear fluid is then obtained. The clear fluid is then combined with the thickener, and additional water is added to provide a hydraulic fluid having the desired water content and viscosity. The optional constituents such as defoamers, corrosion inhibitors, etc., may be added at an appropriate time during preparation of the fluid.
Concentrates according to the invention can be blended with a substantial amount of water to provide fire-resistant hydraulic fluids of improved lubricity and anti-wear characteristics, and of stable viscosity. Even though they have water concentrations in excess of 80%, by weight, the hydraulic fluids of this invention can be used effectively in systems containing vane pumps, and can replace standard hydraulic oils with reductions in cost.

The Lubrificant Modifiers

The lubricant modifiers which may be used in the novel hydraulic fluids of this invention include water- immicsible liquids and also water-miscible or water-soluble or-dispersible liquids and mixtures of such liquids. These lubricant modifiers enhance the lubricating properties of the hydraulic fluids and also function as plasticizers to prevent the formation of tacky deposits in the hydraulic systems in which the hydraulic fluids are employed. In addition, the water-miscible or water-dispersible fluids, such as the alkylene glycols defined more fully hereinafter, at higher concentrations, improve the fluidity and low temperature properties of the hydraulic fluids.
The liquids which may be used as lubricant modifiers include such liquids as aliphatic, cycloaliphatic and aromatic hydrocarbons; chlorinated hydrocarbons; mineral oils; silicone oils such as a dimethyl and methyl phenyl silicones; synthetic hydrocarbon oils; fatty materials such as vegetable oils, fish oils, fatty acids, fatty alcohols and fatty amines; condensation products of fatty acids and alkanolamines, which may be phosphate-modified; ethoxylated fatty amides; glycerides; ethoxylated fatty amines; ethoxylated vegetable oils; organic esters such as di-2-ethylhexyl sebacate or azelate, and trimethylolpropane tricaprylate; glycols and polyglycols; triaryl phosphate esters such as triisopropyl phenyl phosphate; and polyphenyl ethers.
One group of preferred lubricant modifiers are the synthetic hydrocarbon oils of lubricating viscosity. Normally such oils, will range in viscosity from 50 to 700 Saybolt Universal Seconds (SUS) at 100°F (37.8°C). Such synthetic hydrocarbon oils are normally prepared by polymerizing lower monoolefins in the presence of a suitable catalyst such as BF₃ or AICI₃. The lower olefins include, for example, ethylene, propylene and butylene. Other synthetic hydrocarbon oils are poly alpha olefins and alkyl benzenes. Such synthetic hydrocarbon fluids have adequate fluidity at low temperatures.
The water-immiscible lubricant modifiers may comprise naturally occuring hydrocarbons such as mineral oils which may be either parafinic or naphthenic in nature. Such mineral oils should have a viscosity of from about 50 to 700 SUS at 100°F (37.8°C). A preferred mineral oil for use in the hydraulic fluids of this invention is a light lubricating oil of the naphthenic type having a viscosity of 80 to 200 SUS at 100°F (37.8°C), a particularly preferred oil of this type having a viscosity of 100 to 150 SUS at 100°F (37.8°C).
Another group of preferred lubricant modifiers are the condensation products of fatty acids and alkanolamines. These products, which are water dispersible, may be prepared by reacting a fatty acid or fatty ester with an alkanolamine at temperatures on the order of 100° to 160°C. with removal of water of condensation or alcohol. The mol ratio of fatty acid or ester to amine may be in the range of from 2:1 to 1:3. Optionally, a small amount, e.g. 0.01 to 0.05 mols, of phosphoric acid may be present during the reaction.
The fatty acids used in the preparation of the condensates generally should contain from 7 to 22, preferably 12 to 18 carbon atoms and may be saturated or unsaturated, or a mixture of both. Thus, fatty acids suitable for use in preparing the condensates include heptanoic, caprylic, pelargonic, capric, lauric, myristic, palmitic, stearic, oleic and behenic acids. A preferred fatty acid reactant is a mixture of stearic and oleic acids.
Alkanolamines which have been found useful in preparing the condensates include ethanolamine, isopropanolamine, N-methyl ethanolamine, diethanolamine, dipropanolamine, diisopropanolamine, and triethanolamine. A particularly preferred alkanolamine is diethanolamine.
Another group of preferred water-soluble/dispersible lubricant modifiers are the ethoxylated fatty amides, amines, alcohols and vegetable oils. The alkyl group of these fatty materials generally should contain from 7 to 22, preferably 12 to 18 carbon atoms. Such alkyl groups include heptanoyl, caprylyl, nonanoyl, capryl, lauryl, myristyl, stearyl, oleyl and behenyl. Such lubricant modifiers may comprise the fatty material derived from vegetable oils, such as, palmitic, coconut, castor, rapeseed, soya bean, corn, peanut or sunflower oil. In addition such fatty material may be derived from animal fat such as tallow, lard, fish oil and the like.
The degree of ethoxylation of these water soluble/dispersible lubricant modifiers should be from 1 to 20, preferably 4 to 6, moles of ethylene oxide to one mole of fatty amide, amine, alcohol or vegetable oil.
A preferred group of lubricant modifiers which are water-soluble are the alkylene and poly alkylene glycols having the formula RO(C,,H₂nO)_xH, where R is hydrogen or an alkyl group containing 1 to 10 carbon atoms, n is an integer from 2 to 6 and x is an integer from 1 to 70. The alkylene glycols include ethylene and propylene glycol and their higher homologs such as diethylene and dipropylene glycol. The preferred alkylene glycol is ethylene glycol.
Suitable water miscible or water dispersible polyoxyalkylene glycols include polyoxyethylene, polyoxypropylene and poly(oxyethylene, oxypropylene) glycols having molecular weights of from about 200 to about 4000. These polyglycols may be uncapped or capped at the end by a lower alkyl group containing from 1 to 10 carbon atoms. The weight percent of the oxyethylene in the poly(oxyethylene, oxypropylene) glycols should be on the order of at least 20%. A particular preferred polyglycol is the monobutyl ether of poly(oxyalkylene-oxy-1 ,2-propylene) glycol having a molecular weight of about 1500 to 4000.
Amongst suitable mixtures for use as lubricant modifiers there may be mentioned a mixture of a phosphate-modified condensation product of a fatty acid and a dialkanolamine, and a monobutyl ether of poly(oxyethylene-oxy-1,2-prpylene)glycol; a mixture of a polybutene, a polyglycol and a fatty alcohol; a mixture of a mineral oil, a fatty alcohol and a glycol; and a mixture of a fatty alcohol and a glycol.
The lubricant modifiers comprise at least 0.50% and less than 20%, by weight, of the hydraulic fluid. Preferred hydraulic fluids of the invention contain on the order of 1.0 to 10% of lubricant modifier.

The Thickener

The polyether-based thickeners used in the hydraulic fluids of this invention are relatively high molecular weight (molecular weight of at least 7,000). They may be polyoxyalkylene compounds, also referred to herein as polyether polyols, and such compounds may be capped by means of an alpha olefin oxide. The thickeners are water-soluble, or at least water-dispersible. The preferred thickeners are the alpha olefin-capped polyoxyethylene-polyoxypropylene block copolymers containing on the order of 20 to 35%, by weight of 1,2-propolyene oxide groups.
The polyether-based thickeners preferably used in the water-based hydraulic fluids of this invention are selected from two types of normally liquid polyether polyols. Each type is obtained by reacting ethylene oxide, at least one lower alkylene oxide having 3 or 4 carbon atoms, and an active hydrogen compound. However, in one type of thickener, the active hydrogen compound is an aliphatic alcohol having two or more hydroxy groups in the molecule, i.e. a diol or polyol, while in the other type it is an aliphatic monohydric alcohol containing from 4 to 30, preferably 12 to 18, carbon atoms in the aliphatic group. In either instance, these polyether polyols, which may be heteric or block copolymers, may be capped by reaction with an alpha olefin oxide having 12 to 30, preferably 12 to 18, aliphatic carbon atoms. However, those thickeners in which the active hydrogen compound is a diol or polyol may be used in uncapped form, provided they have a sufficiently high molecular weight. Thus, such uncapped polyether polyols must have a molecular weight of at least 7,000 and may have a molecular weight as high as 75,000. Preferred uncapped polyether polyols of this type have a molecular weight of from about 10,000 to 30,000.
If the copolymer thickeners in which the active hydrogen compound is a diol or polyol are capped by reaction with an alpha olefin oxide, the molecular weight thereof should be on the order of 7,000 to 15,000, preferably about 12,000 to 14,000. In either instance, i.e. whether the polyether polyols are of relatively high, 20,000 plus, molecular weight, or of relatively low molecular weight, e.g. less than about 15,000, the weight percent of ethylene oxide groups should be on the order of 25% to 80%. Preferably, the copolymers contain 20 to 35% of 1,2-propylene oxide groups.
The diols used as the active hydrogen compound in the reaction may be glycols, such as ethylene glycol, diethylene glycol and higher glycols. The diols may also contain oxyalkylene groups. Typical of the polyols which may be used as active hydrogen compounds are glycerol, polyglycerol and trimethylol propane.
In preparing these polyether polyols, good results may be obtained by bringing a mixture containing the ethylene oxide and the lower alkylene oxide into intimate contact with the diol or polyol starting compound in the liquid phase, throughout which a suitable catalyst is uniformly dispersed. As catalysts, sodium and potassium hydroxide are preferred. The reaction is carried out at temperatures on the order of 50° to 160°C.
Such polyether polyols in which the active hydrogen compound is a diol and the process for their preparation are described in detail in US-A-2,425,845.
As noted above, the polyether polyols which contain a diol or polyol may either be used as such, or capped with an alpha olefin oxide. Advantageously, it was discovered that a substantially lesser amount of the capped polyol, whether including a diol or polyol or an aliphatic monohydric alcohol as the active hydrogen-containing compound, as compared to an uncapped polyol, could be used to provide a hydraulic fluid of a given viscosity. Thus, for example, in the hydraulic fluids of this invention, 4.8 parts by weight of a capped thickener were found to provide a hydraulic fluid with a viscosity of only 190-200 SUS at 100°F. (37.8°C), as compared to a viscosity of only 75-80 SUS using 12.5 parts of an uncapped thickener (cf. Examples I and II infra).
As previously stated, the alpha olefin oxides utilized to modify or cap the polyether polyols are those containing 12 to 30, preferably 12 to 18 aliphatic carbon atoms, and mixtures thereof. The amount of alpha olefin oxide required to obtain the desired thickeners is 1 to 20%, by weight of the total weight of the capped thickeners.
The capping reaction is carried out by adding the alpha olefin oxide to the polyether polyol, a liquid, and heating the mixture to a temperature of about 50° to 90°C. for about 1 to 2 hours, depending upon batch size. Before addition of alpha olefin oxide, it is desirable to render the polyether polyol as anhydrous as possible.
A second type of preferred thickener is those heteric or block copolymers of ethylene oxide, a lower alkylene oxide and an active hydrogen compound, which preferably is an aliphatic monohydroxy alcohol containing 4 to 30, preferably 12 to 18 aliphatic carbon atoms, capped with an alpha olefin oxide which also contains 12 to 30 aliphatic carbon atoms. Such thickeners and methods for their preparation are disclosed in US-A-4.,288,639.
Typical of the preferred monohydric alcohols for reaction with ethylene oxide and a lower alkylene oxide are butyl alcohol, capryl alcohol, lauryl alcohol, myristyl alcohol, stearyl alcohol, cetyl alcohol and behenyl alcohol. The reaction is carried out using well known alkaline oxyalkylation catalysts, for example, strong bases such as sodium and potassium hydroxides. The reaction can be carried out in the presence of an inert organic solvent, examples of which include aliphatic hydrocarbons, such as hexane and heptane; aromatic hydrocarbons, such as benzene and toluene; chlorinated hydrocarbons such as ethylene dichloride, and the like. Reaction temperatures are as stated above, i.e. on the order of 50° to 160°C.
Preparation of the latter polyether polyols is well known in the art. Further details of preparation of heteric copolymers of lower alkylene oxides are disclosed in US-A-3,829,506. Additional information on preparation of block copolymers of lower alkylene oxides is to be found in US--A-3,535,307.
The polyether polyols in which the active hydrogen compound is an aliphatic monohydric alcohol may be capped with an alpha olefin oxide as described herein above.
The molecular weight of the latter discussed capped thickeners should be in the range of about 7,000 to 15,000, preferably 12,000 to 14,000.
Other polyether polyols which may be capped to provide thickeners according to this invention and methods for their preparation are disclosed in US-A-2,425,755, 3,036,118, 3,595,924, 3,706,714, and 3,829,505; and GB-A-950,844 and 1,228,561.
In the hydraulic fluids of this invention, the thickeners comprise from 1.5 to 15%, by weight, the amount depending upon the particular thickener employed and the viscosity which is desired for the hydraulic fluid. As noted above, the capped thickeners have greater thickening power than do the uncapped thickeners. Thus, lesser amounts of the capped thickeners can be used to provide the hydraulic fluids of the invention with a desired viscosity. Preferably, the hydraulic fluids contain on the average of 2 to 6% of capped thickener or 10 to 15% of uncapped thickener, by weight. By using the preferred quantities of thickeners, the hydraulic fluids will have viscosities in the range of 50 to 200 SUS at 100°F (37.8°C).

The Dispersing Agents

Useful dispersing agents for inclusion in the hydraulic fluids of this invention are reaction products of an alkenyl succinic anhydride (or acid) with water-soluble active hydrogen compounds, an example of which is dialkyl alkanolamine. These dispersing agents are particularly effective in dispersing oil-soluble extreme pressure (EP) additives, such as zinc dialkyl dithiophosphate, in the aqueous fluid where it can act as an anti-wear constituent and provide EP properties.
The alkenyl succinic anhydride (or acid) with which the active hydrogen compound is reacted may be prepared by reacting maleic anhydride with a long chain alpha olefin by conventional procedures. The olefin may be reacted with maleic anhydride (or acid) at temperatures of 1500-250°C., the amount of olefin used being at least the stoichiometric equivalent of the maleic anhydride reactant. A preferred olefin reaction product is a polyisobutene of sufficient chain length to provide the succinic anhydride reaction product with a molecular weight on the order of 500 to 2000, desirably about 800 to 2,000, preferably about 800 to 1200, a molecular weight of about 1,000 being particularly preferred. Thus, the alkenyl succinic anhydride or acid may have from 16 to 30 carbon atoms in the alkenyl group.
As to the other reactant, it is an active hydrogen compound and may be an alkyl alkanolamine having the formula
in which R is hydrogen or an alkyl group containing from 8 to 24 carbon atoms, R' is hydrogen, (C₂H₄0)_xH or (C₃H₆0)_xH, R" is R or R', and x is an integer of from 1 to 50. A particularly preferred alkyl alkanolamine reactant is diethylethanolamine.
Other active hydrogen compounds for reacting with the alkenyl succinic anhydride (or acid) have the formulae

or
in which Z is (C₂H₄0) or (C₃H₆0), R" ' is an alkyl group containing from 8 to 20 carbon atoms, Riv is
or SR" ', Rv is R' or an alkyl group containing from 1 to 4 carbon atoms, and y is an integer from 3 to 10. Preferably, R" ' is a C_a to C₉ alkyl group and y is 5.
The alkenyl succinic anhydride (or acid) is reacted with the active hydrogen compound at a temperature of about 50° to 250°C., preferably 60° to 150°C. for a time sufficient to form the desired reaction product, usually from 1 to 6 hours. The relative amounts of anhydride and active hydrogen compound can vary somewhat, but preferably two mols of such compound are used with each mol of anhydride to ensure complete reaction of the anhydride.
Thus, for example, the dispersing agent may be an ester of an alkenyl succinic anhydride or acid and either an ethoxylated fatty alcohol or an ethoxylated fatty amine.
The hydraulic fluids of the invention contain from 1.25 to 5.0%, preferably 1.25 to 3%, of the dispersing agent in order to ensure proper dispersion of the EP additive and other water-insoluble constituents in the aqueous phase of the hydraulic fluid and give good (low) wear loss results.

The Extreme Pressure (EP) Additives

The extreme pressure (EP) additives used in hydraulic fluids of the invention are diallyl or diaryl dithiophosphates or dithiocarbamates. They may have the respective formulae
where Rv is an alkyl group containing from 4 to 16, preferably 4 to 10 carbon atoms, phenyl or naphthyl, and X is hydrogen, an amine, ammonium, a substituted ammonium compound, a metal of Groups I and II of the Periodic Table, i.e. the alkali metals such as sodium, potassium or lithium, alkaline earth metals, usually magnesium or calcium, and the Group II transition metals, particularly zinc, which is preferred, or manganese, antimony, or M₀₂S₂0₂, and a is an integer of from 1 to 2.
The dithiophosphates may be prepared by reacting an alcohol with phosphorus pentasulfide at a temperature of from 40°-120°C. for a period of 1 to 4 hours. Typical alcohols which may be used in the reaction are such normal alcohols as n-butyl, n-heptyl, n-octyl, n-decyl and n-dodecyl alcohol. Suitable branched chain alcohols include 2-methyl-1-pentanol, 2-ethyl-1-hexanol and 2,2-dimethyl-1-octanol.
An organic or inorganic base may be reacted with the dithiophosphate to form the EP additives for inclusion in the hydraulic fluid. Ashless dithiophosphates may be obtained by reaction with non-metallic bases such as amines, ammonia and substituted ammonium compounds. Reaction with metal oxides or hydroxides produces ashing dithiophosphates which usually are preferred by reason of their properties.
The metals most usually used are those of Groups I and II of the Periodic Table, i.e. the alkali metals, such as sodium, potassium, and lithium, the alkaline earth metals, usually magnesium or calcium, and the Group 11 transition metals, particularly zinc, which is especially preferred. The metal is generally used in the form of its oxide or hydroxide for reaction with dithiophosphoric acid.
The reaction between the dithiophosphoric acid and the base is usually conducted at a temperature of 75°-150°C. over a period of 1-4 hours.
The EP additive is present in the hydraulic fluids of the invention in an amount of from 0.5 to 1.25%, preferably 0.5 to 0.75%, by weight of the fluid, in order to ensure good(low) wear loss results.
The dithiocarbamates are well known compounds and generally may be obtained by reaction of suitable amine and carbon disulfide.

Optional Additives

In addition to the above essential constituents and water, the hydraulic fluids of the invention may also contain other materials such as emulsifiers, corrosion inhibitors, defoamers,-coupling agents, and the like.
Suitable emulsifiers include those having a Hydrophile-Lipophile Balance (HLB) in the range of 3 to 20 (see Chapter 1 of the HLB System published by ICI United States, Inc. (1976)). Examples of such emulsifiers are ethoxylated alkyl phenols or alkyl amines in which the alkyl groups contain from 14 to 24 carbon atoms and the number of ethoxy groups varies from 3 to 10. Long chain, e.g. C_e-C,₈ alcohols can also be used as co-emulsifiers. The hydraulic fluid may contain up to 1.5% of such an emulsifier, preferred amounts of emulsifier being from 0.45 to 1.2%, by weight.
Small amounts, e.g. up to 0.5% by weight, of various silicone defoamers may be present in the hydraulic fluid, as well as small amounts, e.g. up to 0.1 % by weight, of various corrosion inhibitors, such as benzotriazole and tolutriazole. As a vapor phase corrosion inhibitor there may be used various water soluble alkyl alkanolamines of the type used to react with succinic anhydride to form the dispersing agents, described above. Freezing point depressants such as ethylene glycol, if not present as the lubricant modifier, may be included in the hydraulic fluids in amounts sufficient to lower the freezing point to prevent freezing of the fluids at those temperatures encountered in use.
In order to limit shipping and storage costs, it may be desirable to first prepare a water-dilutable concentrate from which the hydraulic fluid may be prepared merely by addition of an appropriate amount of water. Such a concentrate may have the composition given in TABLE I, below.
In preparing a hydraulic fluid of this invention, the oil-soluble lubricant modifier, if present, dispersing agent and EP additive may be mixed together and heated at a temperature of from about 130° to 150°F. (54.4°-65.6°C.) for 30―45 minutes. Various of the optional additives such as the corrosion inhibitors, defoamers, emulsifiers, etc. may be added to the water-miscible lubricant modifier, when present, which is heated to about 150^0-160°F. (65.5°-71.1°C.). Otherwise such optional additives may be added directly to the mixture containing the oil soluble lubricant modifier and EP additive. The two mixtures can then be combined in the absence of heat, water added, and the mixture blended for 45-60 minutes to form a translucent fluid containing 35-45% water. This mixture can then be combined with an appropriate amount of thickener and water to provide a hydraulic fluid of the desired water content, 80% or more, and viscosity.
In order that the invention may be better understood, several examples thereof and comparative examples will now be described, purely by way of illustration. Examples I, III and V describe hydraulic fluids having concentrations of dispersing agent and extreme pressure additive below the ranges specified for those ingredients in accordance with the invention and are included for comparative purposes. The wear loss results reported for such fluids in Examples II, IV and VI are worse (higher) than those reported in Examples VIII and XI―XIII for the hydraulic fluids of Examples VII and X, which are within the scope of the invention.

Example I

A hydraulic fluid of the present invention having the composition set forth in TABLE II was prepared by the method hereinbelow described:
23.3 parts by weight of component (a), 18.0 parts of component (b), and 7.5 parts of component (c), were mixed and heated to 130^0-150°F. (54.4°-65.6°C.) for 30-45 minutes. 1.2 parts of the additives, component (g), were dissolved in 10.0 parts of component (d) which has been heated to 150°―160°F (66°-71°C). The two mixtures were combined; the heat was shut off, and water was added in an amount such that the water comprised 40% by weight of the final mixture. The resulting batch was blended for 45-60 minutes to obtain a uniformly translucent liquid.
5 parts by weight of the translucent liquid, prepared as above, were combined with 12.5 parts of thickener, component (e), and 0.5 part of diethyl ethanolamine, component (f), in sufficient water so that the total of all materials was 100%. The resulting hydraulic fluid has an initial viscosity of 75-80 SUS at 100°F. (37.8°C).

Example II

The hydraulic fluid of Example I was subjected to the following pump test:

Example III

A hydraulic fluid of the present invention having the composition set forth in TABLE IV was prepared by the method hereinbelow described:
23.3 parts by weight of component (a), 18.0 parts of component (b), and 7.5 parts of component (c), were mixed and heated to 130°-150°F (54.4°―65.6°C.). for 30-45 minutes. 1.2 parts of the additives, component (g), were dissolved in 10.0 parts of component (d) which has been heated to 150°-160°F (65.6°-71.1°C.). The two mixtures were combined; the heat was shut off, and water was added in an amount such that the water comprised 40% by weight of the final mixture. The resulting batch was blended for 45―60 minutes to obtain a uniformly translucent liquid.
5 parts by weight of the translucent liquid, prepared as above, were combined with 4.8 parts of the thickener, component (e), and 0.5 parts of diethylethanolamine, component (f), in sufficient water so that the total of all materials was 100%. The resulting hydraulic fluid had an initial viscosity of 190-200 SUS at 100°F. (37.8°C.).

Example IV

The hydraulic fluid of Example III was subjected to the following pump test:

Example V

A hydraulic fluid of the present invention having the composition set forth in TABLE VI was prepared by the method hereinbelow described:
21.2 parts by weight of component (a) and 16.0 parts of component (b) were mixed and heated to 130^0-150°F. (54.4°-65.6°C.) for 45-60 minutes. The heat was shut off and 6.7 parts of component (c) and 7.5 parts of component (g) were added, and the mixture was blended for 30-45 minutes. 0.9 parts of the additive, component (f), were dissolved in 4.5 parts of component (h) which had been heated to 150°-160°F. (65.6°-71.1°C).
The two mixtures were combined. Water was added in an amount such that the water comprised 43.2% by weight of the final mixture. The resulting batch was blended for 45-60 minutes to obtain a uniformly translucent liquid.
5 parts by weight of the translucent liquid, prepared as above, were combined with 5 parts of the thickener, component (e), and 5 parts of the polyglycol, component (d), in sufficient water so that the total of all materials was 100%. The resulting hydraulic fluid has an initial viscosity of 150-250 SUS at 100°F. (37.8°C).

Example VI

The hydraulic fluid of Example V was subjected to the following pump test using the same type of test pump and the same test conditions as in Example IV, TABLE V.

Example VII

A hydraulic fluid of the present invention having the composition set forth in TABLE VIII was prepared by the method hereinbelow described:
12.5 parts by weight of component (a), 10.0 parts of component (b), and 5.0 parts of component (c), were mixed and heated to 130°-150°F. (54.4°-65.6°C.) for 30-45 minutes. 0.6 parts of the additives, component (g), were dissolved in 21.9 parts of component (d) which has been heated to 150°-160°F (65.6°-71.1°C.) The two mixtures were combined; the heat was shut off, and water was added in an amount such that the water comprised 50% by weight of the final mixture. The resulting batch was blended for 45-60 minutes to obtain a uniformly translucent liquid.
10.0 parts by weight of the translucent liquid, prepared as above, were combined with 12.0 parts of the thickener, component (e), and 0.5 parts of diethylethanolamine, component (f), in sufficient water so that the total of all materials was 100%. The resulting hydraulic fluid had an initial viscosity of 70-75 SUS at 100°F. (37.8°C).

Example VIII

The hydraulic fluid of Example VII was subjected to the following pump test:

Example IX

The hydraulic fluid of Example V was subjected to the following pump test:

Example X

A hydraulic fluid of the present invention having the composition set forth on Table XI was prepared by the method herein below described:
38.5 parts of component (a) and 14.0 parts of component (b) were mixed and heated to 130°-150°F (54°-66°C) for 45-60 minutes. The heat was shut off and 11.0 parts of component (c) and 10.0 parts of component (d) were added, and the mixture was blended for 30-45 minutes. 0.3 parts of benzotriazole were dissolved in 6.5 parts of component (e) which have been heated to 150°―160°F (66°-71°C). The two mixtures were combined. 10.7 parts of water were added, and the mixture was blended for 45-60 minutes to obtain a uniformly transparent liquid.
6.5 parts by weight of the transparent liquid, prepared as above were combined with 87.8 parts of water, 2.5 parts of ethylene glycol, 3.0 parts of component (i) and 0.2 parts of silicone defoamer. This mixture was blended for 45-60 minutes until a uniform translucent product was obtained. The resulting hydraulic fluid had an initial viscosity of 210-320 SUS.

Example XI

The hydraulic fluid of Example X was subjected to pump tests using the same type of pump and the same conditions as in Example IV, Table V, except for duration of the tests. The results of these tests are set forth in Table XII, below.

Example XII

The hydraulic fluid of Example X was subjected to the following pump tests, and the test conditions used and results obtained are set forth in Table XIII, below:

Example XIII

The hydraulic fluid of Example X was subjected to pump tests using the same type of pump and the same conditions as in Example IX, Table X except for duration of the tests, and the results obtained are set forth in Table XIV, below:

Claims

1. A high water-based hydraulic fluid in the form of an oil-in-water emulsion comprising (1) from 1.5 to 15% of a polyether-based thickener having a molecular weight of at least 1,000, (2) at least 0.5 of a lubricant modifier, (3) from 1.25 to 5.0% of a dispersing agent which is the reaction product of an alkenyl succinic anhydride or acid and a water soluble active hydrogen compound, (4) from 0.5% to 1.25% of an extreme pressure additive comprising a dialkyl or diaryl dithiophosphate, or a dialkyl or diaryl dithiocarbamate, and (5) at least 80% water, said percentages being by weight based on the total weight of the fluid.

2. A hydraulic fluid according to claim 1 in which said thickener comprises a polyether polyol prepared by reacting ethylene oxide and at least one lower alkylene oxide having 3 or 4 carbon atoms with at least one active hydrogen compound initiator to prepare a heteric or block copolymer, and further reacting said copolymer with at least one alpha olefin oxide, said polyol having a molecular weight of from 7,000 to 15,000.

3. A hydraulic fluid according to claim 2 in which said active hydrogen compound is a diol or polyol.

4. A hydraulic fluid according to claim 2 in which said active hydrogen compound is an aliphatic monohydric alcohol containing from 4 to 30 carbon atoms.

5. A hydraulic fluid according to claim 1 in which said thickener comprises a polyether polyol prepared by reacting a diol or polyol, ethylene oxide and at least one lower alkylene oxide having 3 or 4 carbon atoms to form a heteric or block copolymer, said copolymer having a molecular weight of from 7,000 to 75,000.

6. A hydraulic fluid according to claim 2 in which said thickener comprises a polyether polyol prepared by reacting ethylene oxide and propylene oxide with a lower glycol or polyol to form a block copolymer, and further reacting said copolymer with an alpha olefin oxide containing from 12 to 30 aliphatic carbon atoms, said polyether having a molecular weight of from 7,000 to 15,000.

7. A hydraulic fluid according to claim 4 in which said thickener comprises a polyether prepared by reacting ethylene oxide, propylene oxide and an aliphatic alcohol containing 12 to 18 aliphatic carbon atoms to form a block copolymer, and further reacting said block copolymer with an alpha olefin oxide containing from 12 to 30 aliphatic carbon atoms, said polyether having a molecular weight of from 7,000 to 15,000.

8. A hydraulic fluid according to claim 6 in which said lower glycol or polyol is ethylene glycol.

9. A hydraulic fluid according to any of claims 1 to 8 in which said lubricant modifier is selected from aliphatic hydrocarbons, cycloaliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, mineral oils, silicone oils, synthetic hydrocarbon oils, glycerides, vegetable oils, fish oils, fatty acids, fatty alcohols, fatty amines, condensation products of fatty acids and alkanolamines, phosphate-modified condensation products of fatty acids and alkanolamines, ethoxylated fatty amines, glycols, polyglycols, ethoxylated vegetable oils, ethoxylated fatty amides, organic esters, triaryl phosphate esters and polyphenyl ethers, and mixtures thereof.

10. A hydraulic fluid according to claim 9 in which said lubricant modifier comprises a polybutene having a viscosity of about 400 SUS at 100°F (37.8°C).

11. A hydraulic fluid according to claim 9 in which said lubricant modifier is a phosphate-modified condensation product of a fatty acid and a dialkanolamine.

12. A hydraulic fluid according to claim 9 in which said lubricant modifier is a light lubricating oil of the naphthenic type having a viscosity of about 100 SUS at 100°F (37.8°C).

13. A hydraulic fluid according to claim 9 in which said lubricant modifier is ethylene glycol.

14. A hydraulic fluid according to claim 9 in which said lubricant modifier is a monobutyl ether of poly(oxyethylene-oxy-1,2-propylene) glycol having a molecular weight of from about 1,500 to 4,000.

15. A hydraulic fluid according to claim 9 in which said lubricant modifier comprises a mixture of a phosphate-modified condensation product of a fatty acid and a dialkanolamine, and a monobutyl ether of poly(oxyethylene-oxy-1,2-propylene) glycol.

16. A hydraulic fluid according to claim 10 in which said lubricant modifier comprises a mixture of a polybutene, a polyglycol and a fatty alcohol.

17. A hydraulic fluid according to claim 9 in which said lubricant modifier comprises a mixture of a mineral oil, a fatty alcohol and a glycol.

18. A hydraulic fluid according to claim 9 in which said lubricant modifier comprises a mixture of a fatty alcohol and a glycol.

19. A hydraulic fluid according to any of claims 1 to 18 in which said dispersing agent comprises the reaction product of an alkenyl succinic anhydride or acid and an alkyl alkanolamine of the formula

in which R is hydrogen or an alkyl group containing from 8 to 24 carbon atoms, R' is hydrogen, (C2H40)xH or (C₃H₆O)_xH, R" is R or R' and x is an integer of from 1 to 50, said reaction product having a molecular weight of from about 800 to 2000.

20. A hydraulic fluid according to claim 19 in which said dispersing agent comprises the reaction product of polyisobutenyl succinic anhydride having a molecular weight of about 1,000 and diethyl ethanolamine.

21. A hydraulic fluid according to any of claims 1 to 18 in which said dispersing agent is an ester of an alkenyl succinic anhydride or acid and an ethoxylated fatty alcohol.

22. A hydraulic fluid according to any of claims 1 to 18 in which said dispersing agent is an ester of an alkenyl succinic anhydride or acid and an ethoxylated fatty amine.

23. A hydraulic fluid according to any of claims 1 to 18 in which said dispersing agent is the reaction product of an alkenyl succinic anhydride or acid and a compound of the formula

or

in which Z is (C₂H₄0) or (C₃H₆0), R" is an alkyl group containing from 8 to 20 carbon atoms, R_jv is

or SR" ', R" is R' or an alkyl group containing from 1 to 4 carbon atoms, and y is an integer from 3 to 10.

24. A hydraulic fluid according to any of claims 1 to 23 in which said extreme pressure additive has the formula

in which R^V is an alkyl group containing from 4 to 16 carbon atoms or is phenyl or naphthyl, X is hydrogen, an amine, ammonium or substituted ammonium, sodium, potassium, lithium, calcium, magnesium, manganese or zinc, and a is 1 or 2.

25. A hydraulic fluid according to claim 24 in which said extreme pressure additive is a zinc dialkyl dithiophosphate.

26. A hydraulic fluid according to claim 24 in which said extreme pressure additive is a zinc dialkyl dithiophosphate in which the alkyl groups contain from 4 to 10 carbon atoms.

27. A high water-based hydraulic fluid in the form of an oil-in-water emulsion comprising (1) from 2 to 6% of a thickener comprising a polyether polyol prepared by reacting ethylene oxide, propylene oxide and a lower glycol or polyol to form a block copolymer, and further reacting said block copolymer with an alpha olefin oxide containing from 12 to 18 aliphatic carbon atoms, said polyether having a molecular weight of from about 12,000 to about 14,000 , (2) from 1 to 10% of a lubricant modifier, (3) from 1.25 to 3% of a dispersing agent comprising the reaction product of polyisobutenyl succinic anhydride and diethyl ethanolamine, said reaction product having a molecular weight of about 1,000, (4) from 0.5 to 0.75% of a zinc dialkyl dithiophosphate in which the alkyl groups contain from 4 to 10 carbon atoms, and (5) balance water, said percentages being by weight based on the total weight of the fluid, said fluid containing at least 80% of water.

28. A concentrate for forming a high water-based hydraulic fluid as claimed in any of claims 1 to 26 by addition of water thereto, said concentrate comprising (1) from 5 to 20% of the polyether-based thickener, (2) from 5 to 40% of the lubricant modifier, (3) from 5 to 20% of the dispersing agent, (4) from 1 to 10% of the extreme pressure additive and (5) balance water, said percentages being by weight based on the total weight of the fluid.

29. A concentrate for forming a high water-based hydraulic fluid as claimed in claim 27 by the addition of water thereto comprising (1) from 12 to 18% of the thickener, (2) from 10 to 20% of the lubricant modifier, (3) from 10 to 15% of the dispersing agent, (4) from 2 to 6% of a zinc dialkyl dithiophosphate in which the alkyl groups contain from 4 to 10 carbon atoms, and (5) balance water, said percentages being by weight based on the total weight of the fluid.