Grease composition

Abstract

The present disclosure provides a grease composition containing an ashless phosphonate mixture, the ashless phosphonate mixture consisting of an ashless phosphonate mixture of a cyclic phosphonate species and an oligomeric phosphonate species. The grease composition also includes a metallic soap thickener. The grease compositions disclosed herein exhibit improved antiwear protection under very harsh conditions and loads.

Description

Technical Field

[0001] The present disclosure provides a grease composition comprising an ashless phosphonate mixture and a metal soap thickener. The present invention also relates to a method of using the grease composition. Background Art

[0002] Open gear lubricants generally have properties that include tack that allows adhesion to the gears, erosion resistance, corrosion / polishing / wear protection, and cushioning without buildup. Grease-type open gear lubricants are typically used for the lubrication of open gear systems found in, for example, dragline and electric rope excavators, as well as other equipment found in large open pit mining operations. Open gear lubricants generally function under boundary lubrication conditions due to the extremely high loads they experience in addition to the need for a lubricant formulation that can survive in this environment without causing damage to the equipment.

[0003] The working cycle of these open gear systems typically includes short duration starts, stops and reversals of forward motion that may be considered high speed operation (30m / s-43m / s). This mode of operation is challenging for conventional lubricants, so proper selection of lubrication is important to protect such components. Typical open gear lubricants require high sulfur content to meet high load specifications, which may add negative complexities to the gears, such as increased wear. Therefore, there is a need in the art for an open gear lubricant that meets the high load bearing loads of open gear systems, which will minimize negative effects on gears and equipment. Therefore, the present invention provides a grease-type open gear lubricant that provides, among other things, lubrication and wear protection. Summary of the invention

[0004] The present disclosure provides a grease composition comprising an ashless phosphonate mixture and a metal soap thickener. The grease composition of the present disclosure comprises an ashless phosphonate mixture comprising a cyclic phosphonate of the formula:

[0005]

[0006] Among them, R 1 , R 2 , R 3 and R 4 independently selected from hydrogen, one of a hydrocarbyl group having 1 to 24 or 1 to 12 carbon atoms, and an oligomeric phosphonate of the formula:

[0007]

[0008] Each R 5 is independently a straight or branched hydrocarbon group having 3 to 24 carbon atoms, and n is an integer from 1 to 8. The grease composition also comprises a metal soap thickener as described herein.

[0009] The present disclosure also provides a method for lubricating a mechanical device. The method comprises supplying the above-mentioned grease composition to a mechanical device selected from one or more of a towline, a rope shovel and a mining device. In addition, the present disclosure provides a use of the grease composition in a mechanical device to reduce one or more of wear and corrosion. DETAILED DESCRIPTION

[0010] The disclosure described herein provides grease compositions comprising an ashless phosphonate mixture and a metal soap thickener as well as methods of using the grease compositions and uses of the grease compositions.

[0011] Phosphonate mixture

[0012] The grease composition of the present invention comprises an ashless phosphonate mixture. The phosphonate mixture composition may comprise two or more phosphonate substances. The phosphonate mixture may not be a zinc salt, i.e., the phosphonate mixture may be a composition that is substantially free of zinc. As used herein, "substantially free" means that the amount of the substance under consideration is lower than the amount that will affect the relevant properties of the lubricant in a measurable manner. In one embodiment, the grease composition of the present disclosure is substantially free of zinc. In another embodiment, the grease composition is ashless.

[0013] The phosphonate mixture comprises a phosphonate consisting of a reaction product, such as a condensation product, of phosphonic acid (H3PO3) or a monomeric ester thereof (i) and at least one propylene glycol (ii). The so-called "monomeric" phosphonate means a phosphonate, generally comprising one phosphorus atom and having two independent alkyl groups, each of which has one to six carbon atoms, which can react with a polyol to form an oligomer substance, a polymer substance or other condensate substance. The alkyl group of the monomeric phosphonate can be a relatively low molecular weight group having 1 to 6 or 1 to 4 carbon atoms, such as a methyl, ethyl, propyl or butyl group, so that the alcohol produced when reacting with the alkylene glycol can be easily removed. An exemplary monomeric phosphonate is dimethyl phosphite; other phosphonates include diethyl phosphite, dipropyl phosphite and dibutyl phosphite. Therefore, in some embodiments, the monomeric phosphonate used to prepare the cyclic phosphonate may include dimethyl phosphite.

[0014] Sulfur-containing analogs (e.g., thiophosphites) may also be used. Other esters include trialkyl phosphites. Mixtures of dialkyl phosphites and trialkyl phosphites may also be used. As described above, in these materials, the alkyl groups may be the same or different, and typically each alkyl group independently has 1 to 6 or 1 to 4 carbon atoms.

[0015] The monomeric phosphonate (i) will react or condense with at least one propylene glycol (ii) to form a substance of the disclosed technology, which includes a monomeric cyclic phosphonate substance. The propylene glycol may have at least one hydroxyl group at both the 1st and 3rd positions, and one or more carbon atoms of the carbon atoms of the propyl unit are substituted by one or two alkyl groups, so that the total number of carbon atoms in the propylene glycol ranges from 4 to 12. The molar ratio of phosphonic acid or phosphonate (i) to propylene glycol (ii) may be 0.9:1.1 to 1.1:0.9. In some embodiments, propylene glycol may include alkyl-substituted 1,3-propylene glycol, one or more alkyl substituents of which are located on one or more carbon atoms of the carbon atoms of the propyl unit, so that the total number of carbon atoms in the glycol ranges from 5 to 12 or 6 to 12 or 7 to 12 or 8 to 12 or in certain embodiments 9 to 12 or even 9. That is, the alkyl-substituted propylene glycol may be represented by the following general formula:

[0016]

[0017] Wherein various R groups can be the same or different, and can be hydrogen atoms or hydrocarbon groups, provided that at least one R is an alkyl group and the total number of carbon atoms in the R group is 2 to 9 or 3 to 9, so that the total carbon atoms in the diol will be 1 to 24 or 3 to 24 or 5 to 16 or 6 to 12 or 3 to 12, respectively, and the same is true for other ranges of total carbon amount. Propylene glycol mentioned here means that the two hydroxyl groups are in a 1,3 relationship with each other, that is, separated by a 3-carbon atom chain. Therefore, according to the position of the two hydroxyl groups on the longest alkyl chain of the molecule, propylene glycol can also be named as 2,4-diol or 3,5-diol or 4,6-diol. If 1,3-propylene glycol has one or more secondary hydroxyl groups, the molecule will be considered as an internal diol. In one embodiment, the number of alkyl substituents is two and the total number of carbon atoms in the molecule is 9. Suitable substituents may include, for example, methyl, ethyl, propyl and butyl (in the form of its various possible isomers).

[0018] Examples of suitable 1,3-propanediol may include 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 2,2-dibutyl-1,3-propanediol, 2,2-diisobutyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-propyl-1,3-propanediol, 2-butyl-1,3-propanediol, 2-pentyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, 2,4-dimethyl-2,4-pentanediol, and 2,4-hexanediol. It should be noted that for the sake of clarity, some of the aforementioned nomenclature emphasizes the 1,3-propanediol structure of the molecule. For example, 2-pentyl-1,3-propanediol may also be named 2-hydroxymethyl-1-heptanol, but the latter nomenclature does not clearly illustrate the 1,3-nature of the diol. In other embodiments, 1,3-propanediol may include 2-butyl-2-ethyl-1,3-propanediol (BEPD).

[0019] In another embodiment, the phosphonate mixture comprises the reaction product of (i) a phosphonic acid or an ester thereof and an alcohol mixture comprising (ii) propylene glycol and (iii) an alkanediol having hydroxyl groups in a 1,4 or 1,5 or 1,6 relationship. In the alcohol mixture, the propylene glycol (ii) is always present in an amount greater than the alkanediol (iii). The reaction mixture comprises at least 90 mole % of propylene glycol and 1 to 10 mole % of the alkanediol.

[0020] As described above, the alkanediol (iii) is a 1,4 or 1,5 or 1,6 alkanediol having hydroxyl groups in a 1,4 or 1,5 or 1,6 relationship to each other, separated by 4 to 8 carbon atoms or 4 to 6 carbon atoms, respectively. The first hydroxyl group may be located on carbon atom number 1, i.e., on the alpha carbon of the diol, or the first hydroxyl group may be located on a higher numbered carbon atom. For example, the diol may also be a 2,5-diol, or a 2,6-diol, or a 2,7-diol, or a 3,6-diol, or a 3,7-diol or a 3,8-diol, which will be apparent to those skilled in the art. The alkanediol may be branched (e.g., alkyl substituted) or unbranched, and in one embodiment the alkanediol is unbranched. Unbranched diols, i.e., straight chain diols (α,ω-diols), include 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. Branched or substituted diols include 1,4-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 3,3-dimethyl-1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol and 2,5-dimethyl-2,5-hexanediol. For the technology of the present disclosure, diols (such as 2,5-hexanediol) with one or more secondary hydroxyl groups may be referred to as internal diols. In certain embodiments, alkanediol (iii) may be 1,6-hexanediol. In other embodiments, propylene glycol (ii) may include 2-butyl-2-ethyl-1,3-propanediol (BEPD), and alkanediol (iii) may include 1,6-hexanediol. The ratio of BEPD to 1,6-hexanediol may be from 95.5:4.5 to 99.5:0.5, or from 96:4 to 99:1, or from 98:2 to 99:1, or from 97:3 to 99:1.

[0021] If necessary, the alkanediol (iii) may have added hydroxyl groups, i.e., more than two hydroxyl groups per molecule, or there may be exactly two hydroxyl groups. In one embodiment, there are exactly two hydroxyl groups per molecule. In addition, care should be taken to avoid excessive branching or crosslinking of the product, which may result in the formation of an undesirable gel. Such problems may be avoided by carefully controlling the reaction conditions, such as controlling the reagent ratio and the order of addition, performing the reaction under appropriate dilution conditions, and reacting under low acid conditions. These conditions may be determined by those skilled in the art only by routine experiments.

[0022] In yet other embodiments, the reaction mixture may include (iv) a monohydric alcohol having 1 to 12, or 1 to 8, or 2 to 8, or 2 to 4 carbon atoms. The monohydric alcohol may be present in the reaction mixture in an amount of up to 10 mol %, or up to 8 mol %, or up to 6 mol %, or up to 4 mol %, or up to 2 mol %. In other embodiments, the monohydric alcohol is present in the reaction mixture in 1 wt % to 5 wt %. In some embodiments, the reaction mixture does not contain (i.e., contains 0 mol %) of monohydric alcohol.

[0023] The relative molar amount of phosphonic acid or its monomeric ester (a) to the total molar amount of diol (b) may be in a ratio of 0.9:1.1 to 1.1:0.9, or 0.95:1.05 to 1.05:0.95, or 0.98:1.02 to 1.02:0.98, or about 1:1.

[0024] The phosphonate mixture disclosed herein comprises at least one oligomeric substance comprising 2 to 20 or 3 to 20 phosphorus atoms and at least one cyclic monomeric substance comprising a single phosphorus atom. The phosphonate mixture also comprises a cyclic monomeric substance comprising a single phosphorus atom and a 3-carbon atom chain derived from propylene glycol. The cyclic phosphonate may comprise one phosphorus atom, one hydrogen atom and one oxygen atom from the monomeric phosphonate reactant, as well as carbon and oxygen derived from 1,3-propylene glycol (ii), because 1,3-propylene glycol is able to participate in oligomerization reactions or cyclic ester formation. The oligomeric or polymeric substance may typically comprise 2 or 3 to 20 phosphorus atoms, or alternatively 5 to 10 phosphorus atoms, linked together by alkyl groups derived from 1,3-propylene glycol and / or an alkanediol having two hydroxyl groups in a 1,4, 1,5 or 1,6 relationship, which alkyl groups are less prone to cyclization with phosphorus to form cyclic monomeric substances.

[0025] The oligomeric species of the phosphonate mixture can be represented by the following structure:

[0026]

[0027] (oligomeric substances),

[0028] Each R 5 are independently straight or branched hydrocarbon groups having 3 to 24 carbon atoms, and n is an integer from 1 to 8. In one embodiment, the structure of the oligomeric substance can be defined, wherein R 5 It is a branched hydrocarbon group having 6 to 14 carbon atoms.

[0029] The cyclic species of the phosphonate mixture can be represented by the following structure:

[0030]

[0031] (cyclic substances),

[0032] Among them, R 1 , R 2 , R 3 and R 4 is independently selected from one of hydrogen, a hydrocarbon group having 1 to 24 or 1 to 12 carbon atoms. In one embodiment, a cyclic material structure can be defined, wherein R 3 and R 4 is a hydrogen atom; and R1 and R 2 Both are hydrocarbyl groups having 1 to 12 carbon atoms, or 1 to 8 carbon atoms, or 1 to 6 carbon atoms, or 2 to 6 carbon atoms.

[0033] It is noteworthy that the corresponding structures of the phosphonate mixture can be formed from different alkanediols and 1,3-propanediol.

[0034] The relative amounts of oligomeric and cyclic monomeric species in the reaction mixture will depend to some extent on the specific diols selected and the reaction conditions. When only 1,3-propanediol is used and no alkanediol having two hydroxyl groups in a 1,4 or 1,5 or 1,6 relationship is used, the cyclic phosphonates formed will, for example, comprise about 80% by weight of the total weight of the esters formed and the oligomeric phosphonates will comprise about 20% by weight of the total weight of the esters formed (80:20 cyclic:oligomer).

[0035] For the reaction product prepared from 1,6-hexanediol and 2-butyl-2-ethyl-1,3-propanediol, in the above structure, less than 40 mol% of 1,6-hexanediol and at least 40 mol% of 1,3-propanediol are generally used, because the use of these alcohols in a ratio of 40 mol%:60 mol% will produce a phosphonate with a 50:50 weight ratio of cyclic products to oligomers. The amount of cyclic products obtained by the reaction at 135°C can be roughly shown in the following table:

[0036] Mole % 1,6-hexanediol 4.5 1 Mole % 2-Butyl-2-ethyl-1,3-propanediol 95.5 99 Weight% Cyclic 78 88

[0037] In one embodiment, the phosphonate mixture comprises 50 wt % or more of cyclic phosphonates and 50 wt % or less of oligomeric phosphonates. In another embodiment, the phosphonate mixture comprises 60 wt % or more of cyclic phosphonates and 30 wt % or less of oligomeric phosphonates. In some embodiments, the phosphonate mixture comprises 65 wt % or more of cyclic phosphonates and 27 wt % or less of oligomeric phosphonates. In some embodiments, the phosphonate mixture comprises 70 wt % or more of cyclic phosphonates and 25 wt % or less of oligomeric phosphonates. In some embodiments, the phosphonate mixture comprises 75 wt % or more of cyclic phosphonates and 22 wt % or less of oligomeric phosphonates. In some embodiments, the phosphonate mixture comprises 80 wt % or more of cyclic phosphonates and 20 wt % or less of oligomeric phosphonates. In some embodiments, the phosphonate mixture comprises 60 wt % to 85 wt % of cyclic phosphonates and 15 wt % to 30 wt % or less of oligomeric phosphonates.

[0038] The condensation reaction between the phosphonic acid or phosphonic acid ester and the diol mixture can be achieved by mixing the reagents and heating until the reaction is substantially completed. Alternatively, the phosphonic acid or phosphonic acid ester can be slowly added to the preheated diol mixture. Typically, if a diol mixture is used, the two diols will be mixed with the phosphonic acid or phosphonic acid ester compound simultaneously or almost simultaneously, that is, usually mixed before the reaction with one diol is completed. A small amount of alkaline substances, such as sodium methoxide, may also be present. If methyl phosphonate is used as a reagent, the substantial completion of the reaction may correspond to stopping the release and distillation of methanol from the reaction mixture. Decompression may be advantageously employed in the later stages of the reaction to help remove residual methanol. Suitable temperatures include temperatures in the range of 100°C to 140°C, such as 110°C to 130°C or 115°C to 120°C. If the reaction temperature employed exceeds about 140°C, there may be a risk that the desired product cannot be formed with a useful yield or useful purity because competing reactions may occur. Typically, the reaction time may be as long as 12 hours, depending on the temperature, applied pressure (if any), stirring and other variables. In some cases, reaction times of 2 to 8 hours or 4 to 6 hours may be appropriate.

[0039] The amount of the phosphonate mixture used in the present grease composition may be an amount sufficient to provide 0.01 wt % to 0.3 wt % or to 0.1 wt % phosphorus to the grease composition. Suitable amounts of the phosphonate mixture in the grease composition may be 0.05 wt % to 0.5 wt %, or 0.05 wt % to 0.75 wt %, or 0.05 wt % to 1.0 wt %, or 0.1 wt % to 1.0 wt %, or 0.2 wt % to 1.0 wt %, or 0.3 wt % to 1.0 wt %, or 0.4 wt % to 1.0 wt %, or 0.5 wt % to 1.0 wt %.

[0040] Metal soap thickener

[0041] Thickeners useful in the present grease compositions include simple metal soap thickeners, metal salts of such acid functionalized oils, or mixed soap thickeners in which a fatty acid is reacted with two different metals.

[0042] In one embodiment, the metal soap thickener comprises the reaction product of a complexing acid and a metal compound selected from the group consisting of lithium hydroxide, calcium hydroxide, sodium hydroxide, and mixtures thereof.

[0043] In one embodiment, the metal soap thickener can be a lithium soap. In another embodiment, the metal soap thickener can be a calcium soap. In yet another embodiment, the thickener can be a mixed lithium metal soap and calcium metal soap. In another embodiment, the thickener can be an aluminum complex soap. Such metal soap thickeners and their preparation are well known in the art.

[0044] In one embodiment, the metal hydroxide is selected from lithium hydroxide, calcium hydroxide, sodium hydroxide, or mixtures thereof. In another embodiment, the metal hydroxide comprises or consists of lithium hydroxide. In yet another embodiment, the metal soap thickener comprises or consists of a lithium hydroxide-based metal soap thickener and is present in the grease composition in an amount sufficient to deliver 400 ppm to 3000 pm of lithium to the open gear lubricant composition. In some embodiments of the present invention, the metal soap thickener may include other metals that may be included in the metal hydroxide as impurities but are not intentionally added to the composition.

[0045] In one embodiment, the complexing acid used to make the metal soap thickener is derived from natural plant or animal oils. Examples of plant derived acids are oleic acid, 12-hydroxystearic acid, and ricinoleic acid. Hydrogenated castor oil (i.e., an impure derivative of castor oil containing glycerol, glycerides, and 12-hydroxystearic acid) can also be used to prepare the metal soap thickener. An example of an animal derived fat is tallow.

[0046] The grease compositions disclosed herein may include from about 2 wt % to about 55 wt % of a metal soap thickener, such as 2 wt % to 20 wt % or even 3 wt % to 15 wt % of a metal soap thickener, based on the total weight of the grease composition.

[0047] Other additives

[0048] The grease composition of the present invention may also contain one or more other additives. Such additives, alone or in combination, may be present in an amount of 0 wt % to about 20 wt %, or 0.1 wt % to about 15 wt %, or about 0.5 wt % to about 15 wt %, based on the total weight of the grease composition.

[0049] Other performance additives that can be used in the grease composition include, but are not limited to, metal deactivators, viscosity modifiers, detergents, friction modifiers, anti-wear agents, corrosion inhibitors, tackifiers, extreme pressure (EP) agents, antioxidants, and mixtures thereof. Typically, a fully formulated grease composition may contain at least one or more of these performance additives.

[0050] The antioxidant may be selected from diarylamines, alkylated diarylamines, hindered phenols, molybdenum compounds (such as molybdenum dithiocarbamates or molybdenum disulfide), hydroxy thioethers, trimethyl polyquinolines (e.g., 1,2-dihydro-2,2,4-trimethylquinoline), or mixtures thereof. In one embodiment, the grease composition comprises at least one antioxidant and may contain a mixture of antioxidants. The antioxidant may be present in an amount of 0 wt % to about 5 wt %, or about 0.05 wt % to about 3 wt %, or about 0.1 wt % to about 2.5 wt %, or about 0.2 wt % to about 1.5 wt %, or about 0.3 wt % to about 1 wt %, based on the total weight of the grease composition.

[0051] In one embodiment, the diarylamines and alkylated diarylamines used in the grease composition herein can be selected from phenyl-α-naphthylamine (PANA), alkylated diphenylamines or alkylated phenylnaphthylamines or mixtures thereof. In another embodiment, the alkylated diphenylamines can comprise dinonylated diphenylamines, nonyl diphenylamines, octyl diphenylamines, dioctylated diphenylamines or didecylated diphenylamines. The alkylated diarylamines can include octyl, dioctyl, nonyl, dinonyl, decyl or didecyl phenylnaphthylamines. The alkylated diarylamines can be tetraalkylated diarylamines.

[0052] Hindered phenol antioxidants may also be used in the grease composition. Hindered phenol antioxidants typically contain sec-butyl and / or tert-butyl groups as hindering groups. The phenol group may typically be further substituted with a hydrocarbyl group (typically a straight or branched alkyl group) and / or a bridging group connected to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol or 4-butyl-2,6-di-tert-butylphenol or 4-dodecyl-2,6-di-tert-butylphenol. In one embodiment, the hindered phenol antioxidant may be an ester. A commercially available example of a hindered phenol ester antioxidant is IRGANOX from BASF. TM L 135. A detailed description of suitable ester-containing hindered phenol antioxidant chemistry is found in US Patent 6,559,105.

[0053] In one embodiment, the grease composition may also include a polymer additive that can be used as a tackifier or thickener. Useful tackifiers are known in the art and may include hydrogenated styrene-butadiene rubber, ethylene-propylene copolymers, hydrogenated styrene-isoprene polymers, hydrogenated diene polymers, polyalkylstyrenes, polyolefins, esters of maleic anhydride-olefin copolymers (such as esters described in International Application WO 2010 / 014655), esters of maleic anhydride-styrene copolymers, or mixtures thereof. Tackifiers, such as those described in U.S. Pat. No. 6,300,288, may also be used in the present invention.

[0054] In one embodiment, the grease composition may include a polymeric viscosity modifier. The polymeric viscosity modifier suitable for use in the present grease composition may be selected from a polyolefin different from the ethylene-propylene copolymer used in the ethylene-propylene copolymer mixture described herein, a polymethacrylate, a polyacrylate, or a styrene-maleic anhydride copolymer reacted with an amine. In one embodiment, the polymeric viscosity modifier may include or consist of a polyolefin, which may be a polymer or oligomer of isobutylene or butene or polyisobutylene having a number average molecular weight of 400 to 4000. In one embodiment, if a polymeric viscosity modifier is used in the present invention, it may be included in an amount of 2% to 30% by weight, or even 3% to 28% by weight, or even 5% to 25% by weight of the grease composition.

[0055] In one embodiment, the grease composition may further comprise an overbased metal-containing detergent. The overbased metal-containing detergent may be a calcium, sodium or magnesium overbased detergent.

[0056] The overbased metal-containing detergent may be selected from the group consisting of non-sulfur-containing phenates, sulfur-containing phenates, sulfonates, salicylic acid alkoxides, salicylates, and mixtures thereof or their borated equivalents. The overbased metal-containing detergent may be selected from the group consisting of non-sulfur-containing phenates, sulfur-containing phenates, sulfonates, and mixtures thereof. The overbased detergent may be borated with a boration agent such as boric acid, such as a borated overbased calcium, sodium or magnesium sulfonate detergent, or mixtures thereof.

[0057] In one embodiment, the grease composition may contain a friction modifier. The friction modifier may be present in an amount of 0 wt % to about 6 wt %, or about 0.01 wt % to about 4 wt %, or about 0.05 wt % to about 2 wt %, or about 0.1 wt % to about 2 wt %, based on the total weight of the grease composition.

[0058] Friction modifiers may include materials such as sulfurized aliphatics and olefins, molybdenum dialkyl dithiophosphates, molybdenum dithiocarbamates, or other oil-soluble molybdenum complexes. Commercially available friction modifiers include 855 (commercially available from Vanderbilt Chemicals LLC) or S700 or S710 (commercially available from Adeka, Inc.).

[0059] In one embodiment, the friction modifier may be an oil-soluble molybdenum complex. The oil-soluble molybdenum complex may include molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum blue oxide complex or other oil-soluble molybdenum complex or mixtures thereof. The oil-soluble molybdenum complex may be a mixture of molybdenum oxide and hydroxide - the so-called "blue" oxide. The average oxidation state of the molybdenum of the molybdenum blue oxide is between 5 and 6 and is from MoO2(OH) to MoO 2.5 (OH) 0.5 Examples of oil-soluble MB or MBO (commercially available from Lehmann and Voss GmbH) is a known molybdenum blue oxide complex. The oil-soluble molybdenum complex may be present in an amount of 0 to 5 wt %, or 0.1 to 5 wt %, or 1 to 3 wt %, based on the total weight of the grease composition.

[0060] In one embodiment, the friction modifier may be a long chain fatty acid ester. In another embodiment, the long chain fatty acid ester may be a monoester, and in another embodiment, the long chain fatty acid ester may be a triglyceride, such as sunflower oil or soybean oil or a monoester of a polyol and an aliphatic carboxylic acid.

[0061] In one embodiment, the grease composition comprises an anti-wear agent. Examples of suitable anti-wear agents include titanium compounds, tartrates, tartrimides, oil-soluble amine salts of phosphorus compounds, sulphurized olefins, metal dihydrocarbyl dithiophosphates (such as zinc dialkyl dithiophosphates), phosphites (such as dibutyl phosphite or dioleyl phosphite), phosphonates, thiocarbamate-containing compounds (such as thiocarbamates, thiocarbamate amides, thiocarbamate ethers, alkylene coupled thiocarbamates, and bis(S-alkyl dithiocarbamoyl) disulfides) and oil-soluble phosphamine salts. In one embodiment, the grease composition may also comprise a metal dihydrocarbyl dithiophosphate (such as zinc dialkyl dithiophosphate).

[0062] In one embodiment, the grease composition comprises an extreme pressure agent. The extreme pressure agent may be a sulfur-containing and / or phosphorus-containing and / or nitrogen-containing compound. Examples of extreme pressure agents include polysulfides, sulfided olefins, thiadiazoles or mixtures thereof.

[0063] Examples of thiadiazole extreme pressure agents include 2,5-dimercapto-1,3,4-thiadiazole or oligomers thereof, 2,5-dimercapto-1,3,4-thiadiazole substituted with a hydrocarbyl group, 2,5-dimercapto-1,3,4-thiadiazole substituted with a hydrocarbylsulfide or oligomers thereof. Oligomers of 2,5-dimercapto-1,3,4-thiadiazole substituted with a hydrocarbyl group are generally oligomers of two or more thiadiazole units formed by forming sulfur-sulfur bonds between 2,5-dimercapto-1,3,4-thiadiazole units. Examples of suitable thiadiazole compounds include at least one of dimercaptothiadiazole, 2,5-dimercapto-[1,3,4]-thiadiazole, 3,5-dimercapto-[1,2,4]-thiadiazole, 3,4-dimercapto-[1,2,5]-thiadiazole or 4-5-dimercapto-[1,2,3]-thiadiazole. Typically, a material that is easily available is used, such as 2,5-dimercapto-1,3,4-thiadiazole or 2,5-dimercapto-1,3,4-thiadiazole substituted with a hydrocarbyl group or 2,5-dimercapto-1,3,4-thiadiazole substituted with hydrocarbyl sulfide. In different embodiments, the number of carbon atoms on the hydrocarbyl substituent group includes 1 to 30, 2 to 25, 4 to 20, 6 to 16, or 8 to 10. The 2,5-dimercapto-1,3,4-thiadiazole can be 2,5-dioctyldithio-1,3,4-thiadiazole or 2,5-dinonyldithio-1,3,4-thiadiazole.

[0064] In one embodiment, a polysulfide extreme pressure agent is used, wherein at least 50% by weight of the polysulfide molecules are a mixture of trisulfides or tetrasulfides. In other embodiments, at least 55% by weight or at least 60% by weight of the polysulfide molecules are a mixture of trisulfides or tetrasulfides.

[0065] In one embodiment, polysulfide extreme pressure agent can comprise the sulfurized organic polysulfide from oil, fatty acid or ester, olefin or polyolefin.The oil that can be sulfurized comprises natural or synthetic fluid, such as mineral oil, lard, the carboxylic acid ester (for example, myristyl oleate and oleyl oleate) derived from aliphatic alcohol and fatty acid or aliphatic carboxylic acid, and synthetic unsaturated ester or glyceride.The fatty acid that can be sulfurized comprises those containing 8 to 30 or 12 to 24 carbon atoms.The example of fatty acid comprises oleic acid, linoleic acid, linolenic acid and tall oil.The sulfurized fatty acid ester prepared by the unsaturated fatty acid ester of mixing, such as obtain from animal fat and vegetable oil (comprising tall oil, linseed oil, soybean oil, rapeseed oil and fish oil).

[0066] Polysulfide extreme pressure agent can also comprise the sulphurized olefin derived from wide range olefin.Olefinic hydrocarbon has one or more double bonds usually.In one embodiment, sulphurized olefin contains 3 to 30 carbon atoms.In other embodiments, sulphurized olefin contains 3 to 16 or 3 to 9 carbon atoms.In one embodiment, sulphurized olefin comprises the olefin derived from propylene, isobutylene, amylene or their mixture.In one embodiment, polysulfide comprises the sulphurized polyolefin derived from making as above-mentioned olefin polymerization by known technology.

[0067] In one embodiment, the polysulfides include dibutyl tetrasulfide, methyl sulfide of oleic acid, alkyl phenol sulfides, dipentene sulfides, dicyclopentadiene sulfides, terpenes sulfides, and Diels-Alder adduct sulfides.

[0068] The extreme pressure agent may be present in the grease composition at a level of 0 wt % to about 5 wt %, about 0.01 wt % to about 4 wt %, about 0.01 wt % to about 3.5 wt %, about 0.05 wt % to about 3 wt %, about 0.1 wt % to about 1.5 wt %, or about 0.2 wt % to about 1 wt % of the grease composition.

[0069] In one embodiment, the grease composition may also include a metal deactivator. Useful metal deactivators may include derivatives of benzotriazole (typically tolyltriazole), 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole or 2-alkyldithiobenzothiazole. Metal deactivators may also be described as corrosion inhibitors.

[0070] Corrosion inhibitors useful for mechanical devices include 1-amino-2-propanol, amines, triazole derivatives (including tolyltriazole), dimercaptothiadiazole derivatives, octylamine octanoate, dodecenylsuccinic acid or anhydride and / or condensation products of fatty acids (such as oleic acid) with polyamines.

[0071] In one embodiment, the grease composition includes a boron compound, such as dispersed potassium borate or a potassium borate salt. In one embodiment, the boron compound, such as dispersed potassium borate, may be present in the grease composition in an amount up to 10% by weight of the grease composition.

[0072] In another embodiment, the grease may contain a solid lubricant, which may be a carbonaceous component, such as amorphous carbon, graphite or carbon black. The carbonaceous component may be present in an amount of 0 wt % to about 6 wt %, or about 0.01 wt % to about 4 wt %, or about 0.05 wt % to about 2 wt %, or about 0.1 wt % to about 2 wt % of the total weight of the grease composition.

[0073] In another embodiment, the grease composition of the present invention comprises a phosphorus compound in an amount to deliver 300 ppm to 2000 ppm phosphorus to the grease composition. For example, the phosphorus compound may comprise or consist of a metal dialkylphosphate. In one embodiment, the phosphorus compound may comprise or consist of a zinc dialkyldithiophosphate.

[0074] In another embodiment of the present invention, the grease composition contains a sulfur-containing molybdenum compound, such as from molybdenum disulfide, molybdenum dithiocarbonate, and combinations thereof.Molybdenum disulfide can also be used as a solid lubricant.

[0075] Industrial Applications

[0076] The grease composition of the present invention can be used in applications requiring lubricants, greases, and open gear compositions.

[0077] Grease is a non-Newtonian semi-solid material, and its viscosity cannot be measured in the same way as liquid lubricants. Instead, the "consistency" of a grease refers to how hard the grease is under specified test conditions. Grease consistency is measured by a cone penetration test. Such tests are defined by various standards, such as ISO 2137, ASTM D217, or ASTM D1403. The results of this test allow a consistency grade, such as #2, to be assigned to a grease according to a classification system established by the NLGI (formerly known as the National Lubricating Grease Institute). According to the cone penetration test, softer greases generally have higher cone penetration numbers. Comparisons of grease properties are typically made on greases of the same consistency grade. In the present disclosure, a grease composition has a cone penetration of 0 or 00 measured according to ASTM D1403.

[0078] The grease compositions disclosed herein can be evaluated for wear in the Four-Ball Grease Wear Test (ASTM D2266). This test is designed to compare lubricants in steel-on-steel applications. Additionally, the ability of the grease composition to protect against extreme wear properties is evaluated in a load bearing test, such as ASTM D2596, which provides a load-wear index, weld point, and maximum no-seizure load (LNSL) for the grease composition. The grease composition can be further evaluated for copper corrosion (ASTM D4048) and iron corrosion (or rust) (ASTM D1743).

[0079] While the greases disclosed herein are characterized as having a grease mass curve based on a cone penetration test, the open gear lubricants considered herein have an unidentifiable dropping point. Typically, a dropping point is a property used to define a grease. The dropping point is a temperature at which a grease becomes soft enough to allow oil and materials to separate from the matrix of the grease and fall from the orifice of a test device. The dropping point of a grease can be measured by various tests, such as ISO 2176 (ASTM D566), ASTM D2265, or IP 396 automated dropping point tests. However, the open gear lubricants of the hardness of the present invention are sufficiently mobile that they typically will not remain in the equipment long enough to provide repeatable measurements. As used herein, "unidentifiable dropping point" refers to an open gear lubricant whose hardness is such that it will not produce a repeatable drop point using the methods described herein. In another embodiment, the open gear lubricant of the present invention can be characterized as having a dropping point of less than 50°C, or even less than 40°C, or even less than 30°C, because the open gear lubricant flows at ambient temperature.

[0080] In one embodiment, the present disclosure provides a method of operating a mechanical device, the method comprising supplying a grease composition to the mechanical device, the grease composition comprising an ashless phosphonate mixture, the ashless phosphonate consisting of a cyclic phosphonate of the formula:

[0081]

[0082] Wherein, R1, R2, R3 and R4 are independently selected from one of hydrogen, a hydrocarbon group having 1 to 24 or 1 to 12 carbon atoms, and an oligomeric phosphonate of the following formula:

[0083]

[0084] wherein each R5 is independently a straight or branched hydrocarbon group having 3 to 24 carbon atoms, and n is an integer from 1 to 8; and a metal soap thickener.

[0085] The grease composition can be used in various mechanical devices, for example, towlines, rope shovels and other mining equipment. Such equipment can operate under high loads, such as, for example, passing an 800 kg 4-ball weld test.

[0086] The grease compositions disclosed herein may be better understood with reference to the following examples, which are non-exhaustive and are not intended to limit the scope of the invention.

[0087] Example

[0088] Various phosphorus-containing antiwear additives were evaluated for their ability to reduce or prevent wear in open gear lubricant, low viscosity grease compositions. The phosphorus-containing additives included conventional dithiophosphate compounds, organic phosphites, and cyclic organic phosphonate compounds, as summarized below (Table 1).

[0089] Table 1: Phosphorus-containing antiwear agents

[0090] describe ％P ％S %Zn ％N P1 <![CDATA[Cyclic phosphonate 1 > 14 0 0 0 P2 <![CDATA[Mixed cyclic phosphonates and oligophosphonates 2 > 15 0 0 0 P3 <![CDATA[Zinc dialkyldithiophosphate 3 > 8.5 17.6 9.25 0 P4 Dioleyl phosphite 5.25 0 0 0 P5 <![CDATA[Bis(dithiophosphoric acid diamide ester) 4 > 6.8 14.1 0 2.9

[0091] 1. Cyclic phosphonate of 2-butyl-2-ethylpropane-1,3-diol (70 wt% cyclic material; 26 wt% oligomeric material)

[0092] 2. A mixture of cyclic phosphonates and oligomeric esters prepared from a mixture of 2-butyl-2-ethylpropane-1,3-diol and 1,6-hexanediol (60:40 mol %), (45 wt % cyclic material; 50 wt % oligomeric material)

[0093] 3. Zinc di(methylpentyl) dithiophosphate

[0094] 4. Bis(dithiophosphoric acid) S,S'-((methylenebis(azanediyl))bis(3-oxypropane-3,1-diyl)) ester O,O,O',O'-tetra(iso)octyl ester

[0095] A series of open gear lubricants were prepared to NLGI 0 grade according to ASTM D1403 (400 mm). The open gear lubricants were formulated with conventional additives and several different phosphorus antiwear additives, summarized below (Table 2). The ability of grease formulations to reduce wear was evaluated in the four-ball grease wear test (ASTM D2266). This test is designed to compare lubricants in steel-on-steel applications. In addition, the ability of grease compositions to prevent extreme wear properties is evaluated in load bearing tests, such as ASTM D2596, which provides load-wear index, weld points, and maximum no-seizure load (LNSL) for grease compositions. The ability of grease lubricating compositions to reduce and prevent corrosion was evaluated for copper corrosion (ASTM D4048) and iron corrosion (or rust) (ASTM D1743).

[0096] Table 1: Grease composition 1

[0097] describe Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 <![CDATA[12% lithium-based grease 2 > 28 28 28 28 28 28 <![CDATA[Mineral base oil 3 > 52.7 52.7 52.7 52.7 52.7 52.7 3000Mn polyisobutylene 2.8 2.8 2.8 2.8 2.8 2.8 graphite 3 3 3 3 3 3 Diisobutylene Sulfide 3.25 3.25 3.25 3.25 3 3 Sulfurized isobutylene 4.95 4.95 4.95 4.95 4.95 4.95 Sulfurized vegetable oil 1.25 1.25 1.25 1.25 1.5 1.5 P1 1 1 P2 1 P3 1 P4 1 P5 1 Other additives 3.05 3.05 3.05 3.05 3.05 3.05 Lithium (ppm) (calculated) 760 760 760 760 760 760 Phosphorus (weight %) (calculated value) 0.254 0.222 0.237 0.309 0.309 0.319 Sulfur (wt%) (calculated value) 3.92 3.75 3.89 3.65 3.68 3.68 Zinc (ppm) (calculated value) 925 0 0 0 0 0 Wear mark(nm) 0.82 0.84 0.78 0.64 0.49 0.61

[0098] 1. All treat rates are oil-free (i.e., active material) unless otherwise specified

[0099] 2. 12-Hydroxystearate lithium thickener in 150BS mineral oil (lithium 0.27 wt%)

[0100] 3. 150 bright oil mineral oil (kinematic viscosity at 100°C is 32cSt)

[0101] 4. Other additives include phosphorus-containing EP agents, corrosion inhibitors and adhesion promoters.

[0102] As shown by the results, the use of phosphorus antiwear agents containing a cyclic phosphonate structure provides improved wear protection compared to other conventional phosphorus antiwear agents.

[0103] Unless otherwise specified herein, references to treat rates or amounts of components present in the lubricating compositions disclosed herein are on an oil-free basis, i.e., the amount of active matter. Additionally, unless otherwise specified, "weight %" as used herein shall refer to weight percent based on the total weight of the composition on an oil-free basis.

[0104] As used herein, the term "alkyl" refers to a group having a carbon atom directly connected to the rest of the molecule, wherein the group includes at least a carbon atom and a hydrogen atom. If the alkyl group contains more than one carbon atom, these carbons do not have to be connected to each other. For example, at least two carbons can be connected by a suitable element or group. In various embodiments, the term "alkyl" refers to a group having a carbon atom directly connected to the rest of the molecule, wherein the group is composed of carbon, hydrogen, one or more heteroatoms optionally connected to at least two carbons and optionally no more than two non-hydrocarbon substituents. Suitable heteroatoms will be apparent to those skilled in the art, and include, for example, sulfur, nitrogen, oxygen, phosphorus and silicon. When the alkyl contains heteroatoms, no more than two heteroatoms will be present for every ten carbon atoms in the alkyl group. Suitable non-hydrocarbon substituents are also apparent to those skilled in the art, and include, for example, halogen, hydroxyl, alkoxy, sulfhydryl, alkylthiol, nitro, nitroso and sulfoxyl. Thus, examples of hydrocarbon groups in the context of the present technology include: (i) hydrocarbon groups selected from aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl, cycloalkadienyl) and aromatic groups; (ii) substituted hydrocarbon groups selected from hydrocarbon groups defined in (i) substituted with no more than two non-hydrocarbon substituents and / or one or more hydrocarbon substituents, wherein the non-hydrocarbon substituents are selected from the group consisting of halogen, hydroxyl, alkoxy, mercapto, alkylthiol, nitro, nitroso and sulfoxy groups; (iii) heteroatom-containing hydrocarbon groups selected from hydrocarbon groups defined in (i) containing one or more heteroatoms in a ring or chain, provided that no more than two heteroatoms are present for every ten carbon atoms in the group, the heteroatoms being selected from sulfur, nitrogen, oxygen, phosphorus and silicon. The heteroatom-containing hydrocarbon group may be substituted with no more than two non-hydrocarbon substituents and / or one or more hydrocarbon substituents. Preferably, the term "hydrocarbon group" refers to a group having a carbon atom directly attached to the rest of the molecule, wherein the group consists of carbon and hydrogen atoms.

[0105] The present disclosure is not limited to the specific embodiments described in this application, and these embodiments are intended to illustrate various aspects. Without departing from the spirit and scope of the present invention, many modifications and changes can be made, which will be apparent to those skilled in the art. In addition to those listed herein, according to the foregoing description, functionally equivalent methods and components within the scope of the present disclosure will be apparent to those skilled in the art. Such modifications and changes are intended to fall within the scope of the appended claims. The present disclosure is only limited by the terms of the appended claims and the full range of equivalents given by such claims. It should be understood that the present disclosure is not limited to specific methods, reagents, compounds or compositions, which can certainly vary. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limited.

[0106] Although various compositions, methods, and apparatus are described as "comprising" various components or steps (interpreted to mean "including, but not limited to"), the compositions, methods, and apparatus may also "consist essentially of" or "consist of" the various components and steps, and such terms should be interpreted as limiting a substantially closed group of members.

[0107] With respect to the use of substantially any plural and / or singular terms herein, those skilled in the art may translate from the plural to the singular and / or from the singular to the plural as appropriate, depending on the context and / or application. For clarity, various singular / plural arrangements may be expressly set forth herein.

[0108] Those skilled in the art will understand that, in general, the terms used herein and particularly in the appended claims (e.g., the bodies of the appended claims) are generally intended to be "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," the term "comprising" should be interpreted as "including, but not limited to," etc.). Those skilled in the art will further understand that if a specific number of an introduced claim recitation is intended, such intent will be expressly stated in the claim, and in the absence of such statement, no such intent is present. For example, to aid understanding, the following appended claims may contain the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be interpreted as implying that the introduction of a claim recitation by the indefinite article "a", "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a", "an" (e.g., "a", "an" should be interpreted as meaning "at least one" or "one or more"); the same is true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of introduced claim recitations is explicitly stated, those skilled in the art will recognize that such a statement should be interpreted as meaning at least the stated number (e.g., the unmodified statement "two recitations", without other modifiers, means at least two recitations or two or more recitations). Furthermore, in those cases where a convention similar to “at least one of A, B, and C, etc.” is used, generally speaking, such construction is intended to have the meaning that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include, but is not limited to, systems having only A, only B, only C, A and B, A and C, B and C, and / or A, B, and C, etc.). In those cases where a convention similar to “at least one of A, B, or C, etc.” is used, generally speaking, such construction is intended to have the meaning that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include, but is not limited to, systems having only A, only B, only C, A and B, A and C, B and C, and / or A, B, and C, etc.). One skilled in the art would further understand that, whether in the specification, claims, or drawings, virtually any disjunctive word and / or phrase presenting two or more alternative terms should be understood to contemplate the possibility of including one of the terms, either of the terms, or both of the terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0109] In addition, where features or aspects of the disclosure may be described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0110] As will be understood by those skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof.Any listed range can be easily considered to fully describe and enable the same range to be decomposed into at least equal half, one-third, one-quarter, one-fifth, one-tenth, etc. As a non-limiting example, each range discussed herein can be easily decomposed into lower third, middle third, and upper third, etc. As will be understood by those skilled in the art, all languages ​​(such as "at most", "at least", etc.) include the stated numbers, and refer to the ranges that can be subsequently decomposed into sub-ranges as described above. Finally, as will be understood by those skilled in the art, ranges include each individual member.Therefore, for example, a group with 1% to 3% by weight refers to a group with 1%, 2%, or 3% by weight. Similarly, a group with 1% to 5% by weight refers to a group with 1%, 2%, 3%, 4%, or 5% by weight, etc., including all points therebetween.

[0111] Furthermore, when a stated range is provided for a treat rate, it is contemplated that the range shall include treat rates for individual components and / or mixtures of components. Thus, for example, a range of 1 wt % to 3 wt % contemplates that a given component may be present in the range of 1 wt % to 3 wt % or that a mixture of similar components may be present in the range of 1 wt % to 3 wt %.

[0112] Although the present invention has been explained with respect to its preferred embodiment, it should be understood that various modifications thereof will become apparent to those skilled in the art upon reading this specification. Therefore, it should be understood that the invention disclosed herein is intended to cover these modifications falling within the scope of the appended claims.

Claims

1. A grease composition, comprising: An ash-free phosphonate mixture, the ash-free phosphonate mixture consisting of the following substances: Cyclic phosphonate of the formula: Among them, R 1 , R 2 , R 3 and R 4 independently selected from one of hydrogen, a hydrocarbyl group of 1 to 24 or 1 to 12 carbon atoms, and Oligomeric phosphonates of the formula: in, Each R 5 are independently a linear or branched hydrocarbon group of 3 to 24 carbon atoms, and n is an integer from 1 to 8; and Metal soap thickener.

2. The grease composition according to claim 1, wherein R 3 and R 4 is a hydrogen atom; and R 1 and R 2 Both are hydrocarbyl groups of 1 to 12 carbon atoms, or 1 to 8 carbon atoms, or 1 to 6 carbon atoms, or 2 to 6 carbon atoms.

3. A grease composition according to any one of the preceding claims, wherein R 5 It is a branched hydrocarbon group of 6 to 14 carbon atoms.

4. The grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 50 wt% or more of cyclic phosphonates and 50 wt% or less of oligomeric phosphonates.

5. The grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 60 wt% or more of cyclic phosphonates and 30 wt% or less of oligomeric phosphonates.

6. A grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 65 wt% or more of cyclic phosphonates and 27 wt% or less of oligomeric phosphonates.

7. A grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 70 wt% or more of cyclic phosphonates and 25 wt% or less of oligomeric phosphonates.

8. A grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 75 wt% or more of cyclic phosphonates and 22 wt% or less of oligomeric phosphonates.

9. The grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 80 wt% or more of cyclic phosphonates and 20 wt% or less of oligomeric phosphonates.

10. A grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises 60 to 85 wt% of cyclic phosphonates and 15 to 30 wt% or less of oligomeric phosphonates.

11. The grease composition of any one of the preceding claims, wherein the metal soap thickener comprises the reaction product of a complexing acid and a metal compound selected from the group consisting of lithium hydroxide, calcium hydroxide, sodium hydroxide, and mixtures thereof.

12. The grease composition according to claim 11, wherein the metal hydroxide is selected from lithium hydroxide and calcium hydroxide.

13. The grease composition of claim 11, wherein the metal hydroxide comprises lithium hydroxide.

14. A grease composition according to any one of the preceding claims wherein the metal soap thickener is present in an amount to deliver 500 ppm to 3000 ppm lithium to the composition.

15. A grease composition according to any one of claims 17 to 20, wherein the complexing acid comprises or consists of a 12-hydroxycarboxylic acid.

16. The grease composition according to claim 21, wherein the 12-hydroxycarboxylic acid is 12-hydroxystearic acid or ricinoleic acid or a mixture thereof.

17. A grease composition according to any one of the preceding claims, wherein the metal soap thickener is present in an amount of 2 to 55 wt% or 2 to 20 wt% of the grease composition.

18. A grease composition according to any one of the preceding claims, wherein the composition is substantially free of zinc.

19. A grease composition according to any one of the preceding claims, wherein the composition comprises 0 wt% zinc.

20. The grease composition according to any one of the preceding claims, wherein the composition further comprises one or more additional additives selected from the group consisting of solid lubricants, sulfur-containing extreme pressure (EP) agents, corrosion inhibitors, antioxidants, polymer additives, and combinations thereof.

21. The grease composition according to any one of the preceding claims, wherein the composition further comprises a solid lubricant selected from the group consisting of graphite, carbon black, molybdenum disulfide, and combinations thereof.

22. A grease composition according to any one of the preceding claims, wherein the phosphonate mixture comprises the reaction product of: (i) a phosphonic acid or an ester thereof with (ii) at least 90 mol % of an optionally substituted 1,3-propanediol; and (iii) 1 mol % to 10 mol % of an alkanediol having two hydroxyl groups separated by 4 to 8 carbon atoms.

23. The grease composition of claim 21, wherein the phosphonate mixture further comprises up to 10 mole % of a monohydric alcohol having 1 to 12 carbon atoms.

24. The grease composition of claim 22, wherein the monohydric alcohol has 2 to 8 or 2 to 4 carbon atoms and is present as a reactant at 1 mol% to 5 mol%.

25. A grease composition according to any one of claims 21 to 23, wherein the 1,3-propanediol is substituted with one or more hydrocarbyl groups such that the 1,3-propanediol has a total of 5 to 16 carbon atoms.

26. The grease composition of claim 24, wherein the substituted 1,3-propanediol is selected from 2-ethyl-2-butyl-1,3-propanediol, 2-ethylhexane-1,3-diol, 2,2-dibutyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, or a combination thereof.

27. The grease composition according to any one of claims 21 to 25, wherein the alkanediol is selected from 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or mixtures thereof.

28. A grease composition according to any one of the preceding claims, wherein the amount of the phosphonate mixture ranges from 0.05 wt % to 0.5 wt %, or from 0.05 wt % to 0.75 wt %, or from 0.05 wt % to 1.0 wt %, or from 0.1 wt % to 1.0 wt %, based on the total weight of the grease composition.

29. A method for lubricating a mechanical device, the method comprising supplying the grease composition according to any one of claims 1 to 28 to the mechanical device, the mechanical device being selected from one or more of a towline, a rope shovel and mining equipment.

30. Use of a grease composition according to any one of claims 1 to 28 for reducing wear and corrosion in mechanical devices.

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