Water-based lubricating grease compositions and methods for using same

Abstract

The water-based lubricating grease composition comprises at least 40% by weight of water, a salt-based thickener, a polymer-based thickener, and optionally an inorganic solid-based thickener. A process for preparing the water-based lubricating grease composition may include blending a suitable amount of water with the salt-based thickener to provide a thickened water-based grease, where the salt-based thickener is obtained from contacting a base with a fat, and adding the polymer-based thickener to the thickened water-based grease.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Application No. 63 / 039,018, filed June 15, 2020, which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE INVENTION The present technology relates generally to lubricating greases, and in particular to water-based lubricating greases containing two or more thickeners, and to processes for the production of such lubricating greases. [Background technology]

[0003] Because water is one of the most abundant natural resources on our planet (71% of the Earth's surface is covered by water), water-based lubricating greases are an attractive alternative to hydrocarbon oil-based greases. Water is not only abundant, but also non-toxic, and life cannot exist without it. Water is also recyclable through the water cycle and is a by-product of the combustion of organic fuels. Because water cools much faster than oil, the use of water-based lubricating greases allows for the simultaneous cooling and lubrication of surface metals. Furthermore, water-based lubricating greases can be used in a variety of applications, including agriculture, forestry, marine, food-grade processing, industrial, steelmaking, and high-temperature applications.

[0004] However, there are several drawbacks associated with water-based lubricating greases. One of the major drawbacks of using water in lubricating greases is the limited operating temperature range for such greases (32-212°F / 0-100°C) because the grease cannot be used above the boiling point of water or below the freezing point of water. A second drawback of using water as a base for lubricating greases is the corrosive effect that water can have on the lubricated metal. In addition, water-based lubricating greases are prone to microbial growth in the water-based components. Therefore, there is a need for water-based lubricating greases that address these drawbacks. Summary of the Invention

[0005] In one embodiment, the water-based lubricating grease composition comprises at least 40% by weight of water, a salt-based thickener, and a polymer-based thickener.

[0006] In some embodiments, the composition further comprises an inorganic solid thickener. In some embodiments, the composition may comprise from about 0.1% to about 20% by weight of an inorganic solid thickener. In some embodiments, the composition may comprise from about 1% to about 15% by weight of an inorganic solid thickener.

[0007] In some embodiments, the composition comprises at least 60% water by weight, hi some embodiments, the composition comprises from about 40% to about 90% water by weight, or from 60% to about 90% water by weight.

[0008] In some embodiments, the composition comprises from about 0.1% to about 30% by weight of a salt-based thickener, hi some embodiments, the composition comprises from about 1% to about 20% by weight of a salt-based thickener.

[0009] In some embodiments, the composition comprises from about 0.1% to about 15% by weight of the polymeric thickener, hi some embodiments, the composition comprises from about 1% to about 10% by weight of the polymeric thickener.

[0010] In some embodiments, the composition comprises from about 0.5% to about 30% by weight of total thickeners, hi some embodiments, the composition comprises from about 1% to about 20% by weight of total thickeners.

[0011] In some embodiments, the salt-based thickener comprises a salt of sodium, potassium calcium, or magnesium. In some embodiments, the salt-based thickener comprises a C8-C 32 The present invention includes potassium, sodium, calcium, or magnesium salts of fatty acids, dicarboxylic acids, hydroxy fatty acids, or hydrogenated castor oil. In some embodiments, the hydroxy fatty acid is 12-hydroxystearic acid.

[0012] In some embodiments, the polymeric thickener comprises a naturally occurring polymer or a synthetic polymer. In some embodiments, the polymeric thickener comprises carboxymethyl cellulose or carboxyethyl cellulose, or a salt or derivative thereof. In some embodiments, the polymeric thickener comprises gelatin, agar, bitulin, a polysaccharide, a water-soluble protein, lignin, lignin sulfonate, or a derivative thereof. In some embodiments, the polymeric thickener comprises a polyglycol, a polyalkylene glycol, a polyamide, or a derivative thereof.

[0013] In some embodiments, the solid inorganic thickener comprises fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, or derivatives thereof.

[0014] In some embodiments, the composition further comprises one or more additives which may include a water-soluble corrosion inhibitor, an anti-wear and load-carrying enhancing additive, a water-miscible boiling point elevating agent, a freezing point depressant, and mixtures of any two or more thereof. In some embodiments, the composition further comprises a water-soluble corrosion inhibitor. In some embodiments, the water-soluble corrosion inhibitor is a metal salt of a sulfonic acid, a C8-C 32 These include metal salts of fatty acids, nitrites, alkanolamines, amine salts, imidazolines, acid amides, or combinations thereof.

[0015] In some embodiments, the composition further comprises an anti-wear and load-carrying enhancing additive, which may include molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum disulfide, zinc dialkyldithiophosphate, or overbased calcium sulfonate. In some embodiments, the composition may also comprise water-miscible boiling point elevating and freezing point depressing agents, including glycols, polyglycols, glycerol, propylene glycol, alkaline earth metal salts, and citric acid, salts thereof, or combinations thereof.

[0016] In some embodiments, the composition is a high temperature fire resistant grease. In some embodiments, the composition does not ignite when exposed to an open flame and / or sparks. In some embodiments, the high temperature is above the flash point of the hydrocarbon mineral oil-based grease or the hydrocarbon synthetic oil-based grease and / or above 500°F.

[0017] In some embodiments, the composition is a lubricant for an electric vehicle, whereby electrical conductivity is highly desirable, hi some embodiments, the composition has conductivity that blocks discharge currents that occur in hydrocarbon-based greases and that can damage bearings due to sparks.

[0018] In some embodiments, the compositions are food-safe and / or for use in food processing machinery, hi some embodiments, the compositions comply with NSF H1 regulations for food-safe lubricants and NSF Standard 61 for potable water system lubricants.

[0019] In some embodiments, the compositions are environmentally friendly and biodegradable, ie, the non-water components in the compositions are more than 65% biodegradable in 28 days according to the OECD 301B biodegradability test method standard.

[0020] In some embodiments, the composition is a lubricant for agricultural machinery equipment, forestry equipment, curved rails and flanged side rails in railways, and / or marine applications where the use of hydrocarbon-based greases poses a hazard to aquatic life.

[0021] In one aspect, there is provided a process for preparing any one of the water-based lubricating grease compositions described herein, comprising: blending a suitable amount of water with a salt-based thickener to provide a thickened water-based grease, the salt-based thickener being obtained from contacting a base with a fat; adding a polymeric thickener to the thickened water-based grease.

[0022] In some embodiments, the process further comprises adding an inorganic solid-based thickener. In some embodiments, the process further comprises adding one or more additives. DETAILED DESCRIPTION OF THE INVENTION

[0023] Various embodiments are described below. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. An aspect described in conjunction with a specific embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiment.

[0024] Water-based lubricating grease composition Described herein are water-based lubricating greases suitable for use in a variety of applications, including agricultural machinery, forestry, marine and hydrographic machinery, food-grade processing machinery lubricants, industrial machinery, steelmaking, and high-temperature applications. The water-based grease compositions described herein contain thickeners, such as salt-based thickeners, polymer-based thickeners, and inorganic solid-based thickeners. In some embodiments, the thickeners act synergistically to thicken the grease. In some embodiments, the thickeners minimize water evaporation during use.

[0025] The water-based lubricating greases described herein are renewable and sustainable lubricating greases. Water is not a greenhouse material and does not cause ozone depletion. Water is a renewable material that permeates our planet. Because the water-based lubricating greases herein contain water as a primary component, these greases are considered sustainable lubricants. Sustainable lubrication is defined herein in reference to lubricants composed of compounds based on renewable resources. The water-based lubricating grease compositions herein may utilize other natural and renewable materials, such as the thickeners and additives described herein.

[0026] The water-based lubricating greases described herein have one or more of the following technical advantages over hydrocarbon oil-based greases: The water-based lubricating greases described herein can be used at relatively high temperatures for intermittent periods with low water evaporation due to the addition of thickeners or additives that act to raise the boiling point of water, and most importantly, can trap water through hydrogen bonding, reducing water evaporation at high temperatures. The same thickeners or additives that raise the boiling point of water also depress the freezing point of water, allowing the water-based grease to operate at temperatures much lower than the freezing point of water. Thus, the thickeners and additives work together to extend the operable range of the water-based grease of which they are a part.

[0027] Water-soluble corrosion inhibitors can also be added to the grease to protect the lubricated metal surface from corrosion. The water-based lubricating greases described herein are also manufactured from non-toxic, environmentally friendly materials and are therefore registered as food-grade NSF and NSF61 compliant lubricants, enabling potential use in environmentally sensitive areas. Additionally, the water-based lubricating greases described herein can be used in areas where a fire-resistant lubricating grease is desired, such as high-temperature steelmaking. The use of water-based lubricating greases also allows for the use of water-soluble chemicals with desirable properties that would otherwise not be available in traditional hydrocarbon oil-based greases.

[0028] Provided herein is a water-based lubricating grease composition comprising at least 40% by weight of water, a salt-based thickener, and a polymer-based thickener. The water-based lubricating grease composition may also include an inorganic solid-based thickener.

[0029] As used herein, water-based lubricating grease refers to a grease in which water represents the base fluid for the grease. Water-miscible and water-immiscible components, such as thickeners and / or additives described herein, are added to impart various desired properties to the water-based grease. In some embodiments, the composition comprises at least about 40% water by weight, including at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, and at least about 90%. In some embodiments, the composition comprises from about 40% to about 90% water by weight, or from 60% to about 90% water by weight, including from about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, and about 90% water by weight. In some embodiments, the composition comprises about 40% to about 90% water by weight, including about 60% to about 90% water by weight.

[0030] The water-based lubricating grease compositions described herein may further comprise an inorganic solid thickener. Exemplary inorganic solid thickeners include, but are not limited to, fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, and derivatives thereof. Other exemplary inorganic solid thickeners include, but are not limited to, silicic acid, silica gel, mica, talc, graphite, boron nitride, zinc oxide, polytetrafluoroethylene (PTFE), and cyanuric acid and its salts (e.g., zinc cyanurate).

[0031] In some embodiments, the composition comprises from about 0.1% to about 20% by weight of inorganic solid thickener, including about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, or about 20% by weight, in some embodiments, wherein the composition comprises from about 0.5% to about 10% or from about 1% to about 15% by weight of inorganic solid thickener.

[0032] The water-based lubricating grease compositions described herein may contain a salt-based thickener. Exemplary salt-based thickeners include, but are not limited to, sodium, potassium, calcium, and magnesium salts. Salt-based thickeners contemplated for use include fatty acid metal salts and organic salts of amines, alkanolamines, and their derivatives. Other examples of salt-based thickeners include C8-C 32 Included are potassium, sodium, calcium, or magnesium salts of fatty acids, dicarboxylic acids, hydroxy fatty acids, or hydrogenated castor oil. In some embodiments, the hydroxy fatty acid is 12-hydroxystearic acid.

[0033] In some embodiments, the composition comprises from about 0.1% to about 30% by weight of salt-based thickener, including about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, or about 30% by weight. In some embodiments, the composition comprises from about 1% to about 15% or from about 1% to about 20% by weight of salt-based thickener.

[0034] The water-based lubricating grease compositions described herein may include a polymeric thickener. The polymeric thickener may be a naturally occurring polymer or a synthetic polymer. Exemplary polymeric thickeners include, but are not limited to, carboxymethyl cellulose, carboxyethyl cellulose, and salts or derivatives thereof. Other examples of polymeric thickeners include, but are not limited to, gelatin, agar, vitulin (obtained from birch tree barks), polysaccharides, water-soluble proteins, lignin, lignin sulfonates, and derivatives thereof. In some embodiments, the polymeric thickener comprises a polyglycol, polyalkelene glycol, polyamide, polyacrylic acid, polyvinyl acetate, polyacrylate, maleic acid / acrylic copolymer, styrene / maleic anhydride resin, acrylate copolymer, or fluoroacrylate, or a derivative thereof. The polymeric thickener may also comprise a mixture of any two or more such thickeners exemplified herein.

[0035] In some embodiments, the composition comprises from about 0.1% to about 30% by weight of polymeric thickener, including about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, or about 30% by weight. In some embodiments, the composition comprises from about 0.1% to about 15%, about 1% to about 10%, or about 1% to about 15% by weight of polymeric thickener.

[0036] The water-based lubricating grease compositions described herein comprise from about 0.5 wt. % to about 30 wt. % total thickeners, including from about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 15, about 20, about 25, or about 30 wt. % total thickeners, based on the total weight of the water-based lubricating grease composition. In some embodiments, the total thickeners may include salt-based thickeners and polymer-based thickeners. In some embodiments, the total thickeners may include salt-based thickeners, polymer-based thickeners, and inorganic solid-based thickeners. In some embodiments, the compositions comprise from about 0.5 wt. % to about 20 wt. %, from about 1 wt. % to about 20 wt. %, or from about 1 wt. % to about 15 wt. % total thickeners.

[0037] The water-based lubricating grease compositions described herein are formulated to pass the FE8 test. The FE8 test is the FAG Wear Bearing Grease Test, an industry standard test used to evaluate the ability of a tested bearing grease to minimize friction and wear. The FE8 test involves loading a pair of bearings with the test grease, applying a constant load (typically measured in Newtons), and running the bearings continuously at a specified speed and temperature for a specified period of time (i.e., 500 hours / 21 days). Torque and temperature are continuously measured during the test. If the bearing torque or temperature exceeds a specified maximum value, the machine is automatically shut down. If 500 hours are achieved without the torque or temperature exceeding the specified maximum value, the test is considered a pass. The weight loss of the bearing elements (rollers, inner ring, outer ring, and cage) is then recorded to determine how successful the grease was in minimizing wear. In some embodiments, the bearing type is a tapered roller bearing. In some embodiments, the FE8 test conditions are a load of 50 kN (kilonewtons) and a rotational speed of 75 RPM with fan cooling during the test.

[0038] Additives can also be added to water-based lubricating grease compositions to impart various desired properties. Additives contemplated for use herein include one or more of the following: water-soluble corrosion inhibitors, antiwear and load-carrying enhancing additives, water-miscible boiling point elevating agents, freezing point depressants, and mixtures of any two or more thereof. Microencapsulated water-soluble additives can also be incorporated into the water-based lubricating grease compositions described herein. Detergents can also be incorporated to remove wear and defects that may form during friction of lubricated metal surfaces. Such detergents can improve wear characteristics and increase the life and cleanliness of lubricated metal parts.

[0039] In some embodiments, the water-based lubricating grease composition includes a water-soluble corrosion inhibitor. Exemplary water-soluble corrosion inhibitors include alkyl or alkylaryl sulfonic acids, metal salts of alkyl or alkylaryl sulfonic acids (e.g., sodium, calcium, and magnesium), C8-C 32 These include, but are not limited to, metal salts of fatty acids, nitrites, alkanolamines, amine salts, imidazolines, acid amides, or combinations of any two or more thereof.

[0040] In some embodiments, the water-based lubricating grease composition further comprises an anti-wear and load-carrying enhancing additive. Exemplary anti-wear and load-carrying enhancing additives include, but are not limited to, molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum disulfide, zinc dialkyldithiophosphate, overbased calcium sulfonate, triphenylthiophosphate, phosphate ester, fatty acid ester, polyol ester, trimethylolpropane ester, pentaerythritol ester, polyalkylene glycol, polyalkylene glycol ester, or a mixture of any two or more thereof.

[0041] In some embodiments, the water-based lubricating grease composition further comprises a water-miscible boiling point elevating agent and a freezing point depressant. Exemplary water-miscible boiling point elevating agent and a freezing point depressant include, but are not limited to, glycols, polyglycols, glycerol, propylene glycol, alkaline earth metal salts, polyglycols having a molecular weight sufficient to thicken the compositions described herein in the range of about 1000 g / mol to about 500,000 g / mol, and citric acid, or salts or combinations thereof.

[0042] The manufacturing process Also provided in one aspect is a process for preparing a water-based lubricating grease composition, the process comprising blending a suitable amount of water with a salt-based thickener to provide a thickened water-based grease, the salt-based thickener being obtained from contacting a base with a fat, and adding a polymer-based thickener to the thickened water-based grease.

[0043] In some embodiments, the process further comprises adding an inorganic solid-based thickener. In some embodiments, the process further comprises adding one or more additives, such as those described herein.

[0044] In one embodiment, the water-based grease composition is prepared in an open kettle or pressure grease cooking kettle, such as a Stratco contactor or autoclave. For the open kettle cooking procedure, a suitable amount of water, such as about 40% water, and a base, such as potassium hydroxide or sodium hydroxide, are pumped into the grease cooking vessel, and then fats, such as 12-hydroxystearic acid, hydrogenated castor oil, stearic acid, and dicarboxylic acids, are added to the kettle. During addition, the temperature naturally rises due to the exothermic nature of the saponification reaction. The temperature is then maintained within a suitable range (i.e., about 100-150°F) until all of the fat has reacted with the base to provide a thickened water-based grease.

[0045] The next step in the preparation is to add a first suitable amount of water to the thickened water-based grease or formed soap. This amount can be about 10% to about 80% by weight of the total water required for the grease composition. A polymeric thickener is then added. Examples of polymeric thickeners include, but are not limited to, carboxymethyl cellulose, carboxyethyl cellulose, and their derivatives, with their sodium and potassium salts added to provide a secondary thickening effect. Other natural polymers, such as gelatin, agar, vitulin, polysaccharides, water-soluble proteins, lignin, lignin sulfonates, and their derivatives, can also be added. The water-based grease is then pumped to a finishing kettle, where it is gradually cooled. Once the appropriate temperature, such as about 100°F, is reached, the inorganic solid thickener (if used) can be added. Exemplary inorganic solid thickeners include fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, and their derivatives. Examples of inorganic solid thickeners include untreated fumed silica, organically modified silica, and organically treated bentonite, also known as rheological additives. Performance and other functional additives can be added after the solid inorganic thickener. Exemplary functional additives include phosphate esters, trimethylopropane esters, pentaerythritol esters, amine-derived antioxidants, phenol-derived antioxidants, sulfonate-derived corrosion inhibitors, and triphenylphosphate esters. The grease is ground (homogenized) and thoroughly mixed with the additives. A second, additional water addition is then performed to achieve the desired consistency (i.e., NLGI grade or degree of softness) of the water-based grease. A similar procedure can be performed in one kettle, from start to finish, without the need to transfer the grease from the cooking kettle to the finishing kettle.

[0046] Purpose Water-based lubricating grease compositions can be used in a variety of commercial applications. The water-based lubricating greases described herein can be used in applications requiring extreme temperature resistance. For example, water-based lubricating greases, especially high dropping point greases, can be used in steelmaking. The water-based lubricating greases described herein can also be used in applications requiring fire resistance. Because the components of the water-based lubricating grease compositions are non-toxic and environmentally friendly, the water-based lubricating greases described herein can be used in food applications and applications where environmental safety is a concern, including the lubrication of forestry and agricultural machinery, railway lubrication, off-highway machinery lubrication, marine and harbor cranes, and tugboat and boat lifts. For example, the water-based lubricating greases can be registered as food-grade greases by the National Sanitation Foundation (NSF) and / or can be registered as Kosher and Halal. It is also possible to use water-based lubricating grease compositions to lubricate bearings in food processing plants. In some embodiments, the water-based lubricating grease composition may be used in bearings requiring high electrical conductivity (e.g., e-mobility and electric vehicles).

[0047] Water-based lubricating grease compositions can have high flame retardancy so that the grease will not ignite even when exposed to open flames and sparks encountered in high-temperature metal processing plants (steel mills). In some embodiments, the composition is a high-temperature fire-resistant grease. In some embodiments, the composition is fire-resistant when exposed to open flames and / or sparks. Fire resistance can include self-extinguishing compositions or complete fire resistance. In some embodiments, the high temperature is above the flash point of the hydrocarbon mineral oil-based grease or hydrocarbon synthetic oil-based grease and / or above 500°F.

[0048] In some embodiments, the water-based lubricating grease composition may be a lubricant for an electric vehicle, whereby electrical conductivity is highly desirable. In some embodiments, the composition has conductivity that blocks discharge currents that occur in hydrocarbon-based greases and that can cause sparks and damage bearings.

[0049] In some embodiments, the water-based lubricating grease composition is environmentally friendly and biodegradable. In some embodiments, the non-water components in the composition are more than 65% biodegradable in 28 days according to the OECD 301B Biodegradability Test Method Standard. In some embodiments, the composition is a lubricant for agricultural machinery equipment, forestry equipment, railroad curved rails and flange side rails, and / or marine applications where the use of hydrocarbon-based greases poses a risk to aquatic life.

[0050] The invention having thus been generally described will be more readily understood with reference to the following examples, which are provided by way of illustration and are not intended to limit the invention. [Example]

[0051] Example 1: Water-based lubricating grease with two thickeners. The grease was made in an open kettle. In the room temperature open kettle cooking procedure, approximately 40% by weight HO and approximately 1-5% by weight KOH or NaOH were pumped into the grease cooking vessel, followed by the addition of fat to the kettle. For this example, the fats used were oleic acid and stearic acid. The temperature naturally rose due to the exothermic nature of the saponification reaction, forming soap (saponified fat). The temperature was then maintained at 100-150°F until all the fat had reacted with the KOH or NaOH, causing substantial thickening of the grease.

[0052] Approximately 20% by weight of the total water was then added to the formed soap, followed by the addition of the polymeric thickener, in this example carboxymethyl cellulose, to provide a secondary thickening effect.

[0053] The grease was then pumped to a finishing kettle where it was allowed to cool slowly. When the temperature reached approximately 100°F, solid additives and other functional additives were added according to Table 1. The grease was ground and thoroughly mixed with the additives, and additional water was added to obtain the desired consistency of the grease (NLGI grade or degree of softness).

[0054] Table 1 shows the specific ingredients and amounts of the grease formulation prepared in this example. Table 2 below shows the performance characteristics for a water-based grease with two thickeners: a salt-based thickener and a polymer-based thickener.

[0055] [Table 1]

[0056] [Table 2] 1 = The grease sample was cooled to the required temperature and then pressurized with nitrogen at 150 psi. The amount of grease pumped per minute at this temperature and pressure was then calculated. 2 = The tested grease was loaded into a pair of tapered roller bearings and run for 500 hours under the specified load and speed. Torque and temperature were constantly monitored throughout the run. The machine was set to automatically shut down if the temperature or torque exceeded a specific value based on the speed and load settings. The weight loss of all bearing components was measured before and after the test and the results were reported.

[0057] As can be seen from the table above, the water-based grease with two thickeners performed similarly to the oil-based grease with a dropping point similar to that of a simple lithium grease, which is typically in the range of 160-200°C, as found in lubricating grease literature familiar to those skilled in the art (e.g., "Lubricants and Lubrication," Volume 2, Chapter 16, Lubricating Grease, Edited by T. Mang and W. Dresel, 3rd Edition, Publisher Wiley-VCH, 2017). The water-based grease was pumped at temperatures as low as -20°C (-4°F) and as high as 189°C (372°F). The grease also passed the FE8 wear resistance test at a relatively high load of 50 kN and a moderate speed of 75 RPM for 21 days (500 hours), with very little wear and without exceeding the maximum allowable torque for this test condition.

[0058] The water-based grease of this example also passed a corrosion resistance test using a synthetic seawater environment. The seawater test environment exposes the grease to very harsh conditions for any grease, especially a water-based grease. However, the water-based grease with two thickeners passed this test in synthetic seawater for 48 hours. The synthetic seawater chemical composition used was as follows:

[0059] [Table 3] * The remaining balance was made up of water.

[0060] The total salt concentration for the above synthetic seawater composition was 4.1953%.

[0061] The water-based grease with two thickeners demonstrated a moderate range of extreme temperature capacity, with a weld load result of approximately 200 kgf ("kilogram force"), according to the Standard Test Method for Testing the Load Capacity of Lubricating Greases in the 4-Ball Weld Load Test ASTM D2596. The water-based grease exhibited very good anti-wear characteristics, supported by a small wear scar diameter in the 4-Ball Wear Standard Test Method ASTM D2266. Finally, the water-based grease did not cause copper corrosion when tested according to ASTM D130. This result indicates that the water-based greases described herein can be safely used in lubricating bearings and other moving parts that contain copper or are made of copper alloys, such as brass and bronze.

[0062] Example 2: Water-based lubricating grease with three thickeners. The grease was made in an open kettle. In the open kettle cooking procedure, approximately 40% by weight water and approximately 1-5% by weight KOH or NaOH were pumped into the grease cooking vessel along with the fat. For this example, the fats used were oleic acid, steric acid, and 12-hydroxystearic acid. As the saponification reaction proceeded, the temperature naturally increased. The temperature was then maintained at approximately 100-150°F until all of the fat had reacted with the KOH or NaOH, causing substantial thickening of the grease.

[0063] The second step was to add 20% water to the formed soap along with a polymer thickener. Sodium carboxymethyl cellulose and polyacrylic acid were used in this example as shown in the table below. Natural polymers such as lignin sulfonate were also used.

[0064] The grease was then pumped to a finishing kettle where it was gradually cooled. When the temperature reached approximately 100°F, a third inorganic solid thickener was added. In this example, the third inorganic solid thickener was untreated fumed silica, organically modified silica, and organically treated bentonite, also known as rheological additives. After the addition of the third solid thickener, performance additives and other functional additives were added. For this example, the functional additives were phosphate ester, trimethylopropane ester, pentaerythritol ester, amine-derived antioxidant, phenol-derived antioxidant, sulfonate-derivative corrosion inhibitor, and triphenyl phosphate ester. The grease was milled (homogenized), thoroughly mixed with the additives, and additional water was added to achieve the desired consistency (NLGI grade or softness) of the grease.

[0065] Table 4 shows the specific ingredients and amounts of the grease formulation prepared in this example. Table 5 lists performance data for water-based greases with three thickeners: a salt-based thickener, a polymer-based thickener, and an inorganic solid-based thickener.

[0066] [Table 4]

[0067] [Table 5] 1 = The grease sample was cooled to the required temperature and then pressurized with nitrogen at 150 psi, then the amount of grease pumped per minute at this temperature and pressure was calculated. 2 = The tested grease was loaded into a pair of tapered roller bearings and run for 500 hours under the specified load and speed. Torque and temperature were constantly monitored throughout the run. The machine was set to automatically shut down if the temperature or torque exceeded a specific value based on the speed and load settings. The weight loss of all bearing components was measured before and after the test and the results were reported. 3 = The tested grease was loaded into a pair of tapered roller bearings and run for 500 hours under the specified load and speed. Torque and temperature were constantly monitored throughout the run. The machine was set to automatically shut down if the temperature or torque exceeded a specific value based on the speed and load settings. The weight loss of all bearing components was measured before and after the test and the results were reported.

[0068] As can be seen from Table 5, the water-based greases with the three thickeners performed similarly to conventional oil-based greases, with dropping points similar to those of the lithium complex greases, which are typically in the range of 220 to 280°C, as reported in lubricating grease literature familiar to those skilled in the art (e.g., "Lubricants and Lubrication, Volume 2, Chapter 16 Lubricating Grease," Edited by T. Mang and W. Dresel, 3rd Edition, Publisher Wiley-VCH, 2017). The water-based greases were pumped at temperatures as low as -20°C (-4°F) and operated at temperatures as high as approximately 260°C (approximately 500°F). The water-based greases passed the FE8 wear resistance test at a relatively high load of 50 kN and a moderate speed of 75 RPM for 21 days (500 hours), with very little wear and without exceeding the maximum allowable torque for this test condition (<60 N).

[0069] The water-based greases also passed a corrosion resistance test using a synthetic seawater environment, which is a very harsh condition for any grease to withstand. However, the water-based greases with three thickeners passed this test in synthetic seawater for 48 hours. The synthetic seawater chemical composition used is outlined in Table 3.

[0070] The water-based grease demonstrated an extremely high load capacity of 250 kgf weld load results according to the Standard Test Method for Testing the Load Capacity of Lubricating Greases in the 4-Ball Weld Load Test ASTM D2596. The water-based grease also demonstrated very good anti-wear characteristics, supported by the small wear scar diameter in the 4-Ball Wear Standard Test Method ASTM D2266. Finally, the water-based grease did not cause copper corrosion when tested according to ASTM D130. This result indicates that the water-based greases described herein can be safely used to lubricate bearings and other moving parts that contain copper or are made of copper alloys, such as brass and bronze.

[0071] Paragraph 1. A water-based lubricating grease composition, comprising: At least 40% by weight of water; A salt-based thickener, a polymeric thickener. Paragraph 2. The composition of Paragraph 1, wherein the composition further comprises an inorganic solid-based thickener. Paragraph 3. The composition of Paragraph 2, wherein the composition comprises about 0.1% to about 20% by weight of an inorganic solid-based thickener. Paragraph 4. The composition of Paragraph 3, wherein the composition comprises about 1% to about 15% by weight of an inorganic solid-based thickener. Paragraph 5. The composition of any one of Paragraphs 1 to 4, wherein the composition comprises at least 60% by weight of water. Paragraph 6. The composition of Paragraph 5, wherein the composition comprises from about 40% to about 90% water by weight, or from 60% to about 90% water by weight. Paragraph 7. The composition of any one of Paragraphs 1 to 6, wherein the composition comprises from about 0.1% to about 30% by weight of a salt-based thickener. Paragraph 8. The composition of Paragraph 7, wherein the composition comprises about 1% to about 20% by weight of a salt-based thickener. Paragraph 9. The composition of any one of Paragraphs 1 to 8, wherein the composition comprises from about 0.1% to about 15% by weight of a polymeric thickener. Paragraph 10. The composition of Paragraph 9, wherein the composition comprises about 1% to about 10% by weight of a polymeric thickener. Paragraph 11. The composition of any one of Paragraphs 1 to 10, wherein the composition comprises from about 0.5% to about 30% by weight of total thickeners. Paragraph 12. The composition of Paragraph 11, wherein the composition comprises from about 1% to about 20% by weight of total thickeners. Paragraph 13. The composition of any one of Paragraphs 1 to 12, wherein the salt-based thickener comprises a salt of sodium, potassium calcium, or magnesium. Paragraph 14. Salt-based thickeners are C8-C 32 14. The composition of any one of paragraphs 1 to 13, comprising a potassium salt, a sodium salt, a calcium salt, or a magnesium salt of a fatty acid, a dicarboxylic acid, a hydroxy fatty acid, or a hydrogenated castor oil. Paragraph 15. The composition of Paragraph 14, wherein the hydroxy fatty acid is 12-hydroxystearic acid. Paragraph 16. The composition of any one of Paragraphs 1 to 15, wherein the polymeric thickener comprises a naturally occurring polymer or a synthetic polymer. Paragraph 17. The composition of Paragraph 16, wherein the polymeric thickener comprises carboxymethyl cellulose or carboxyethyl cellulose, or a salt or derivative thereof. Paragraph 18. The composition of Paragraph 16, wherein the polymeric thickener comprises gelatin, agar, vitulin, a polysaccharide, a water-soluble protein, lignin, lignin sulfonate, or a derivative thereof. Paragraph 19. The composition of Paragraph 16, wherein the polymeric thickener comprises a polyglycol, a polyalkylene glycol, a polyamide, or a derivative thereof. Paragraph 20. The composition of any one of Paragraphs 2 to 19, wherein the solid inorganic thickener comprises fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, or derivatives thereof. Paragraph 21. The composition of any one of Paragraphs 1 through 20, wherein the composition further comprises one or more additives selected from the group consisting of water-soluble corrosion inhibitors, anti-wear and load-carrying enhancing additives, water-miscible boiling point elevating agents, freezing point depressants, and mixtures of any two or more thereof. Paragraph 22. The composition of any one of Paragraphs 1 to 20, wherein the composition further comprises a water-soluble corrosion inhibitor. Paragraph 23. The water-soluble corrosion inhibitor is a metal salt of a sulfonic acid, C8-C 32 23. The composition of paragraph 22, comprising a metal salt of a fatty acid, a nitrite, an alkanolamine, an amine salt, an imidazoline, an acid amide, or a combination thereof. Paragraph 24. The composition of any one of Paragraphs 1 through 20, wherein the composition further comprises an antiwear and load-carrying enhancing additive comprising a molybdenum dithiocarbamate, a molybdenum dithiophosphate, a molybdenum disulfide, a zinc dialkyldithiophosphate, or an overbased calcium sulfonate. Paragraph 25. The composition of any one of Paragraphs 1 to 20, wherein the composition further comprises a water-miscible boiling point elevating agent and freezing point depressant comprising a glycol, a polyglycol, glycerol, propylene glycol, an alkaline earth metal salt, and citric acid, or a salt or combination thereof. Paragraph 26. The composition of any one of Paragraphs 1 to 25, wherein the composition is a high-temperature fire-resistant grease. Paragraph 27. The composition of Paragraph 26, wherein the composition does not ignite when exposed to an open flame and / or sparks. Paragraph 28. The composition of Paragraph 26, wherein the elevated temperature is above the flash point of the hydrocarbon mineral oil-based grease or the hydrocarbon synthetic oil-based grease and / or above 500°F. Paragraph 29. The composition of any one of Paragraphs 1 to 25, wherein the composition is a lubricant for an electric vehicle, whereby electrical conductivity is highly desirable. Paragraph 30. The composition of Paragraph 29, wherein the composition has conductivity that blocks discharge currents that occur in hydrocarbon-based greases and that can result in sparks and damage bearings. Paragraph 31. The composition of any one of Paragraphs 1 to 25, wherein the composition is food safe and / or for use in food processing machinery. Paragraph 32. The composition of Paragraph 31, wherein the composition complies with NSF H1 regulations for food-safe lubricants and NSF Standard 61 for potable water system lubricants. Paragraph 33. The composition of any one of Paragraphs 1 to 25, wherein the composition is environmentally friendly and biodegradable. Paragraph 34. The composition of Paragraph 33, wherein the non-water components in the composition are more than 65% biodegradable in 28 days according to the OECD 301B Biodegradability Test Method Standard. Paragraph 35. The composition of Paragraph 34, wherein the composition is a lubricant for agricultural machinery equipment, forestry equipment, curved rails and flanged side rails of railways, and / or marine applications where the use of hydrocarbon-based greases poses a risk to aquatic life. Paragraph 36. A process for preparing the water-based lubricating grease composition according to Paragraph 1, comprising: blending a suitable amount of water with a salt-based thickener to provide a thickened water-based grease, the salt-based thickener being obtained from contacting a base with a fat; adding a polymeric thickener to the thickened water-based grease. Paragraph 37. The process of Paragraph 36, wherein the process further comprises adding an inorganic solid-based thickener. Paragraph 38. The process of Paragraphs 36 or 37, wherein the process further comprises adding one or more additives.

[0072] As used herein, the following definitions of terms shall apply unless otherwise indicated.

[0073] As used herein, "about" will be understood by one of ordinary skill in the art and will vary to some extent depending on the context in which it is used. If there are uses of the term that are not clear to persons of ordinary skill in the art, given the context in which it is used, "about" will mean up to plus or minus 10% of the particular term.

[0074] The terms "a," "an," and "the," and similar referents in the context of describing elements (particularly in the context of the claims below) should be construed to cover both the singular and the plural unless otherwise indicated herein or the content clearly contradicts. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually listed herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or the content clearly contradicts otherwise. The use of any and all examples, or exemplary language (e.g., "etc.") provided herein is intended merely to better illustrate embodiments and does not impose limitations on the scope of the claims unless otherwise indicated. No language herein should be construed as indicating any non-claimed element as essential.

[0075] The embodiments illustratively described herein may suitably be practiced in the absence of any element or elements, limitation, or limitations not specifically disclosed herein. Thus, for example, terms such as "comprising," "including," and "containing" should be read expansively and without limitation. Additionally, the terms and expressions used herein are used as terms of description, not limitation, and the use of such terms and expressions is not intended to exclude any equivalents of the shown and described features or portions thereof, although it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase "consisting essentially of" will be understood to include those elements specifically recited, as well as those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase "consisting of" excludes any elements not specified.

[0076] As will be understood by those skilled in the art, for all purposes, particularly in terms of providing a written description, all ranges disclosed herein encompass any and all possible subranges and combinations thereof. It will be readily recognized that any recited range fully describes and allows for the same range to be subdivided into at least two, three, four, five, ten, etc. As a non-limiting example, each range discussed herein can be readily subdivided into a lower third, a middle third, an upper third, etc. Additionally, as will be understood by those skilled in the art, all terms such as "maximum," "at least," "greater than," "less than," etc. refer to ranges that are inclusive of the recited numbers and that can then be subdivided into the subranges discussed above. Finally, as will be understood by those skilled in the art, a range includes each individual member.

[0077] All publications, patent applications, issued patents, and other documents referenced herein are incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions contained in the descriptions incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

[0078] It is contemplated that any of the compositions described herein may possess any combination of the above-described properties. It will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the scope or spirit of the invention in its broader aspects, as defined in the claims that follow. Another aspect of the present invention may be as follows. [1] A composition comprising: At least 40% by weight of water; A salt-based thickener, a polymeric thickener; The composition, wherein the composition is a water-based lubricating grease. [2] The composition according to [1], wherein the composition further comprises an inorganic solid thickener. [3] The composition according to [2], wherein the composition contains about 0.1% by weight to about 20% by weight of the inorganic solid thickener. [4] The composition according to [3], wherein the composition contains about 1% by weight to about 15% by weight of the inorganic solid thickener. [5] The composition according to any one of [1] to [4] above, wherein the composition contains at least 60% by weight of water. [6] The composition according to [5], wherein the composition contains about 40% by weight to about 90% by weight of water, or 60% by weight to about 90% by weight of water. [7] The composition according to any one of [1] to [6], wherein the composition contains about 0.1% by weight to about 30% by weight of the salt-based thickener. [8] The composition according to [7], wherein the composition contains about 1% by weight to about 20% by weight of the salt-based thickener. [9] The composition according to any one of [1] to [8], wherein the composition contains about 0.1% by weight to about 15% by weight of the polymer thickener.

[10] The composition according to [9], wherein the composition comprises about 1% by weight to about 10% by weight of the polymeric thickener.

[11] The composition according to any one of [1] to

[10] , wherein the composition contains about 0.5% by weight to about 30% by weight of a total thickener.

[12] The composition according to

[11] , wherein the composition comprises about 1% by weight to about 20% by weight of a total thickener.

[13] The composition according to any one of [1] to

[12] , wherein the salt-based thickener comprises a salt of sodium, potassium, calcium, or magnesium.

[14] The salt-based thickener is C 8 ~C 32 The composition according to any one of [1] to

[13] above, which contains a potassium salt, a sodium salt, a calcium salt, or a magnesium salt of a fatty acid, a dicarboxylic acid, a hydroxy fatty acid, or a hydrogenated castor oil.

[15] The composition according to

[14] , wherein the hydroxy fatty acid is 12-hydroxystearic acid.

[16] The composition according to any one of [1] to

[15] , wherein the polymer thickener comprises a naturally occurring polymer or a synthetic polymer.

[17] The composition according to

[16] , wherein the polymeric thickener comprises carboxymethyl cellulose or carboxyethyl cellulose, or a salt or derivative thereof.

[18] The composition according to

[16] , wherein the polymer thickener comprises gelatin, agar, vitulin, polysaccharides, water-soluble proteins, lignin, lignin sulfonate, or derivatives thereof.

[19] The composition according to

[16] , wherein the polymer thickener comprises a polyglycol, a polyalkylene glycol, a polyamide, or a derivative thereof.

[20] The composition according to any one of [2] to

[19] , wherein the solid inorganic thickener comprises fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, or a derivative thereof.

[21] The composition according to any one of [1] to

[20] above, further comprising one or more additives selected from the group consisting of water-soluble corrosion inhibitors, anti-wear and load-carrying enhancing additives, water-miscible boiling point elevating agents, freezing point depressants, and mixtures of any two or more thereof.

[22] The composition according to any one of [1] to

[20] above, further comprising a water-soluble corrosion inhibitor.

[23] The water-soluble corrosion inhibitor is a metal salt of sulfonic acid, C 8 ~C 32 The composition according to

[22] , comprising a metal salt of a fatty acid, a nitrite, an alkanolamine, an amine salt, an imidazoline, an acid amide, or a combination thereof.

[24] The composition according to any one of [1] to

[20] above, further comprising an anti-wear and load-carrying enhancing additive comprising molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum disulfide, zinc dialkyldithiophosphate, or overbased calcium sulfonate.

[25] The composition according to any one of [1] to

[20] above, further comprising a water-miscible boiling point elevating agent and freezing point depressant, including glycol, polyglycol, glycerol, propylene glycol, an alkaline earth metal salt, and citric acid, or a salt or combination thereof.

[26] The composition according to any one of [1] to

[25] , which is a high-temperature fire-resistant grease.

[27] The composition according to

[26] , wherein the composition does not ignite when exposed to an open flame and / or sparks.

[28] The composition according to

[26] , wherein the high temperature is a temperature exceeding the flash point of the hydrocarbon mineral oil-based grease or the hydrocarbon synthetic oil-based grease and / or exceeding 500°F.

[29] The composition according to any one of [1] to

[25] , wherein the composition is a lubricant for electric vehicles, whereby electrical conductivity is highly desirable.

[30] The composition according to

[29] , wherein the composition has conductivity that prevents discharge currents that occur in hydrocarbon-based greases and that can damage bearings due to sparks.

[31] The composition according to any one of [1] to

[25] above, which is food-safe and / or can be used in food processing machinery.

[32] The composition according to

[31] , wherein the composition complies with NSF H1 regulations for food-safe lubricants and NSF Standard 61 for drinking water system lubricants.

[33] The composition according to any one of [1] to

[25] above, which is environmentally friendly and biodegradable.

[34] The composition according to

[33] , wherein the non-water components in the composition are more than 65% biodegradable in 28 days according to the OECD 301B biodegradability test method standard.

[35] The composition according to

[34] , wherein the composition is a lubricant for agricultural machinery equipment, forestry equipment, curved rails and flanged side rails of railways, and / or marine applications where the use of hydrocarbon-based greases poses a danger to aquatic life.

[36] A process for preparing a water-based lubricating grease composition comprising at least 40% by weight of water, a salt-based thickener, and a polymer-based thickener, comprising: blending a suitable amount of water with the salt-based thickener to provide a thickened water-based grease, the salt-based thickener being obtained from contacting a base with a fat; adding said polymeric thickener to said thickened water-based grease.

[37] The process according to

[36] , further comprising adding an inorganic solid thickener.

[38] The process according to

[36] or

[37] , further comprising adding one or more additives.

Claims

1. 1. A composition comprising: At least 55% by weight of water; C 8 ~C 32 a salt-based thickener including a potassium salt, a sodium salt, a calcium salt, or a magnesium salt of a fatty acid, a dicarboxylic acid, a hydroxy fatty acid, or a hydrogenated castor oil; a polymeric thickener comprising lignin sulfonate; an inorganic solid thickener comprising fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, or derivatives thereof; The composition, wherein the composition is a water-based lubricating grease.

2. The composition of claim 1, wherein the composition comprises from 0.1% to 20% by weight of the inorganic solid thickener.

3. 3. The composition of claim 1, wherein the composition comprises at least 60% by weight of water.

4. The composition of claim 3, wherein the composition comprises 40% to 90% by weight of water.

5. The composition of any one of claims 1 to 4, wherein the composition comprises from 0.1% to 30% by weight of the salt-based thickener.

6. The composition of any one of claims 1 to 5, wherein the composition comprises from 0.1% to 15% by weight of the polymeric thickener.

7. A composition according to any preceding claim, wherein the composition comprises from 0.5% to 30% by weight of total thickeners.

8. The composition of any one of claims 1 to 7, wherein the inorganic solid thickener comprises fumed silica and hydrophobized fumed silica.

9. 9. The composition of claim 8, wherein the fumed silica and hydrophobized fumed silica are present in a 1:1 weight ratio.

10. The composition of any one of claims 1 to 9, wherein the inorganic solid thickener further comprises talc.

11. 11. The composition of any one of claims 1 to 10, wherein the composition further comprises one or more additives selected from the group consisting of water-soluble corrosion inhibitors, anti-wear and load-carrying enhancing additives, water-miscible boiling point elevating agents, freezing point depressants, and mixtures of any two or more thereof.

12. The composition comprises a metal salt of a sulfonic acid, C 8 ~C 32 11. The composition of any one of claims 1 to 10, further comprising a water-soluble corrosion inhibitor comprising a metal salt of a fatty acid, a nitrite, an alkanolamine, an amine salt, an imidazoline, an acid amide, or a combination thereof.

13. The composition comprises: (i) antiwear and load-carrying enhancing additives including molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum disulfide, zinc dialkyldithiophosphate, or overbased calcium sulfonate; or (ii) Water-miscible boiling point elevating and freezing point depressing agents, including glycols, polyglycols, glycerol, propylene glycol, alkaline earth metal salts, and citric acid, or salts or combinations thereof. The composition of any one of claims 1 to 10, further comprising:

14. at least 55% by weight of water, C 8 ~C 32 1. A process for preparing a water-based lubricating grease composition comprising a salt-based thickener comprising a potassium, sodium, calcium, or magnesium salt of a fatty acid, a dicarboxylic acid, a hydroxy fatty acid, or hydrogenated castor oil, a polymer-based thickener comprising a lignin sulfonate, and an inorganic solid-based thickener comprising fumed silica, silanized fumed silica, hydrophobized fumed silica, bentonite, clay, or derivatives thereof, comprising: blending a suitable amount of water with the salt-based thickener to provide a thickened water-based grease, the salt-based thickener being obtained from contacting a base with a fat; adding the polymeric thickener to the thickened water-based grease; adding said inorganic solid thickener to said thickened water-based grease to provide said water-based lubricating grease composition.

15. 15. The process of claim 14, wherein the process further comprises adding one or more additives.

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