Calcium Carbonate Greases

This application claims priority from U.S. Provisional Patent Application No. 63/633,319, filed on Apr. 12, 2024, which is incorporated by reference herein in its entirety.

The present disclosure generally relates to lubricating greases.

Lubricating greases are used in numerous applications to provide protection from friction, wear, extreme pressures, and corrosion during usage. Typically, a lubricating grease includes three core sets of materials: a solid structural component, a liquid lubricating phase, and performance enhancing additives. Intricate balancing of each of these materials is desired to optimize the cost and performance of lubricating greases.

In one embodiment, a lubricating grease includes calcium carbonate about 25 wt. %-75 wt. % of the lubricating grease, and the calcium carbonate forms a stable particle suspension or a colloidal dispersion in the lubricating grease. The lubricating grease further includes a base oil at a balanced amount.

A lubricating grease may include a solid structural component, a liquid lubricating phase, and performance enhancing additives. The form of each of these materials can vary significantly and employ numerous approaches to achieve a satisfactory end performance. The present disclosure is directed to several approaches to optimize a balance between cost and performance of lubricating greases. For example, one approach is through the inclusion of filler or bulking materials that can provide bulk volume to the material to reduce the amounts of higher-cost structural components or lubricating phases without overly compromising the end properties and performance.

Common filler/buking materials may include various natural clays and minerals such as kaolin, attapulgite, montmorillonite, wood pulp, metal oxides, calcium carbonate, etc. Present disclosure evaluates various filler materials to arrive at a unique approach to the formulation of low-cost and high-performance greases. Screening of an extensive series of naturally occurring and synthetic calcium, aluminum, and magnesium oxides and carbonates led to the discovery of calcium carbonates (CaCO) that provide unique benefits to lubricating greases when present in the concentration range discussed in the present disclosure.

The calcium carbonates of selected concentration ranges disclosed herein function as a structural component that forms a stable particle suspension or a colloidal dispersion in the lubricating grease and may exhibit synergistic benefits when used together with other components of the grease formulations disclosed in the present disclosure. Calcium carbonates outside the specifically selected window of the present disclosure may not exhibit the synergistic benefits of desired grease properties and performance.

The selected calcium carbonates disclosed herein may be in any suitable amorphous or crystalline forms. In some embodiments, the selected calcium carbonate may be in calcite crystal structure of the rhombohedral or scalenohedral form. The selected calcium carbonates disclosed herein may have an average particle size of about 1-5 micrometers (μm), about 2-4 μm, about 3 μm, or any other suitable size ranges. The selected calcium carbonates disclosed herein may be formed via precipitation production methods, any other suitable methods, or may be obtained in the natural occurring forms.

The selected calcium carbonates disclosed herein are not directed to use for making calcium sulfonate greases, in which calcium sulfonate greases are made by converting a fluid detergent that contains amorphous calcium carbonate to a grease containing calcite particles. Different from the usage in making calcium sulfonate, the calcium carbonates in the present disclosure retain the crystal structure in the lubricating greases.

The calcium carbonate greases disclosed herein may be formulated such that the calcium carbonates act as a bulking material that can provide a bulk volume to the material to reduce the amount of higher-cost structural components or lubricating phases without overly compromising the end properties and performance. Calcium carbonates are present in the present grease formulation as a structural component and form a stable particle suspension or a colloidal dispersion of calcium carbonates in liquid lubricating phases. The presence of the calcium carbonates at a such high concentration range significantly reduces or replaces/forgoes the usage of traditional structural components in lubricating greases.

In one embodiment, the lubricating grease disclosed herein includes calcium carbonate about 15%-80% by weight (wt. %), about 20 wt. %-80 wt. %, about 20 wt. %-75 wt. %, about 30 wt. %-75 wt. %, about 40 wt. %-75 wt. %, about 50 wt. %-75 wt. %, about 60 wt. %-75 wt. %, about 30 wt. %-60 wt. %, or about 40 wt. %-50 wt. % of the lubricating grease and a balanced amount of base oil and additives. A “balanced amount” means adding up to 100 wt. % of the lubricating grease. For example, in a lubricating grease of 80 wt. % calcium carbonate, a balanced amount of base oil and additives is 20 wt. %. The amount of additives may be about 0 wt. %-15 wt. %, about 0.01 wt. %-10 wt. %, about 0.01 wt. %-8 wt. %, about 0.01 wt. %-7 wt. %, about 0.01 wt. %-6 wt. %, about 0.01 wt. %-5 wt. %, about 0.01 wt. %-4 wt. %, about 0.01 wt. %-3 wt. %, about 0.01 wt. %-2 wt. %, or about 0.01 wt. %-1 wt. %.

The base oil may include any or a combination of the American Petroleum Institute (API) Group 1, 2, 3, and 4 base oils. These include paraffinic, naphthenic, poly-a-olefin and combinations thereof with no restrictions on the viscosities used. Additionally, the base oil may include API group 5 base oils which are mostly compatible with the exception of poly-glycol or other water-soluble oils which are not compatible for the calcium carbonate grease disclosed herein.

In one embodiment, the lubricating grease disclosed herein includes calcium carbonate of about 25 wt. %-75 wt. %, about 30 wt. %-70 wt. %, about 35 wt. %-70 wt. %, about 40 wt. %-70 wt. %, about 35 wt. %-70 wt. %, about 40 wt. %-70 wt. %, about 45 wt. %-70 wt. %, about 50 wt. %-70 wt. %, about 55 wt. %-70 wt. %, about 60 wt. %-70 wt. %, about 65 wt. %-70 wt. %, or about 67 wt. % of the lubricating grease. The lubricating grease disclosed herein includes a balanced amount of base oil, about 25 wt. %-75 wt. %, about 30 wt. %-70 wt. %, about 30 wt. %-65 wt. %, about 30 wt. %-60 wt. %, about 30 wt. %-65 wt. %, about 30 wt. %-60 wt. %, about 30 wt. %-55 wt. %, about 30 wt. %-50 wt. %, about 30 wt. %-45 wt. %, about 30 wt. %-40 wt. %, about 30 wt. %-35 wt. %, or about 33 wt. % of the lubricating grease. The lubricating grease disclosed herein further includes a balanced amount of additives.

In one embodiment, the lubricating grease disclosed herein may include calcium carbonate with a polymer, which may include but are not limited to olefin copolymers, styrene olefin copolymers, polymethylmethacrylates, functionalized copolymers, and others. For example, the lubricating grease disclosed herein may include calcium carbonate of about 25 wt. %-75 wt. %, a polymer of about 0.5 wt. %-2 wt. %, and a balanced amount of base oil about 23 wt. %-74.5 wt. %.

In one embodiment, the lubricating grease disclosed herein may include a hybrid formulation including a first structural component (calcium carbonate) and a second structural component (different from calcium carbonate).

In another embodiment, the lubricating grease disclosed herein may include a poly-hybrid formulation including a first structural component (calcium carbonate) and two or more structural components in addition to calcium carbonate.

The structural components in addition to calcium carbonates may be selected from calcium 12-hydroxystearate (e.g., calcium 12-HSA), calcium sulfonate, lithium thickener, lithium complex thickener, calcium complex thickener, polyurea, bentonite clays, aluminum thickener, aluminum complex thickeners, and any other suitable thickeners.

In one embodiment, the hybrid formulation includes a first structural component (calcium carbonate) of about 1 wt. %-50 wt. %, about 10 wt. %-50 wt. %, about 15 wt. %-50 wt. %, about 20 wt. %-50 wt. %, about 25 wt. %-50 wt. %, about 30 wt. %-50 wt. %, about 35 wt. %-50 wt. %, or about 40 wt. %-50 wt. %. The hybrid formulation further includes a second structural component, e.g., selected from calcium 12-HSA, calcium sulfonate, lithium thickener, lithium complex thickener, calcium complex thickener, polyurea, bentonite clays, aluminum thickener, aluminum complex thickeners, and any other suitable thickeners, of about 5 wt. %-35 wt. %, about 7 wt. %-30 wt. %, about 9 wt. %-25 wt. %, about 10 wt. %-20 wt. %, about 10 wt. %-15 wt. %, about 35 wt. %, about 29.9 wt. %, about 24.8 wt. %, about 24.8 wt. %, about 19.7 wt. %, about 14.5 wt. %, about 14.4 wt. %, about 12.2 wt. %, about 9.9 wt. %, about 7.57 wt. %, or about 5.29 wt. %. The hybrid formulation including the first and second structural components is balanced by a sufficient amount of base oil and additives, for example, the base oil may be about 5 wt. %-45 wt. %, 10 wt. %-45 wt. %, or 15 wt. %-45 wt. %, and the additives may be about 0.1 wt. %-15 wt. %.

In one embodiment, the poly-hybrid formulation includes a first structural component (calcium carbonate) of about 1 wt. %-50 wt. %, about 10 wt. %-50 wt. %, about 15 wt. %-50 wt. %, about 20 wt. %-50 wt. %, about 25 wt. %-50 wt. %, about 30 wt. %-50 wt. %, about 35 wt. %-50 wt. %, or about 40 wt. %-50 wt. %. The poly-hybrid formulation further includes at least two different structural components, e.g., selected from calcium 12-HSA, calcium sulfonate, lithium thickener, lithium complex thickener, calcium complex thickener, polyurea, bentonite clays, aluminum thickener, aluminum complex thickeners, and any other suitable thickeners, of about 5 wt. %-35 wt. %, about 7 wt. %-30 wt. %, about 9 wt. %-25 wt. %, about 10 wt. %-20 wt. %, about 10 wt. %-15 wt. %, about 35 wt. %, about 29.9 wt. %, about 24.8 wt. %, about 24.8 wt. %, about 19.7 wt. %, about 14.5 wt. %, about 14.4 wt. %, about 12.2 wt. %, about 9.9 wt. %, about 7.57 wt. %, or about 5.29 wt. %. The poly-hybrid formulation including calcium carbonate and at least two other different structural components is balanced by a sufficient amount of base oil and additives, for example, the base oil may be about 5 wt. %-45 wt. %, 10 wt. %-45 wt. %, or 15 wt. %-45 wt. %, and the additives may be about 0.1 wt. %-15 wt. %.

In one embodiment, the hybrid calcium carbonate composition may include calcium sulfonate of about 6 wt. %-15 wt. %, calcium carbonate of about 25 wt. %-50 wt. %, and a balanced amount of base oil and optionally additives.

In one embodiment, the hybrid calcium carbonate composition may include calcium calcium 12-HSA of about 2.5 wt. %-7.5% wt.%, calcium carbonate of about 25 wt. %-50 wt. %, and a balanced amount of base oil, and optionally additives.

In one embodiment, the poly-hybrid calcium carbonate composition may include calcium 12-HSA of about 1 wt. %-1.5 wt. %, calcium sulfonate of about 10 wt. %-15 wt. %, calcium carbonate of about 25 wt. %-35 wt. %, and a balanced amount of base oil, and optionally additives.

Tables 1-8 shows examples of several calcium carbonate grease formulations with corresponding performance properties evaluated based on their resistance to low temperature flow pressure, water spray off, and extreme pressure conditions. The resistance to low temperature flow pressure is tested according to DIN 51805 standard. The resistance to water spray off is tested according to ASTM D4049 standard. The resistance to extreme pressure is tested according to ASTM D2596 four ball extreme pressure standard and ASTM D5706 SRV extreme pressure. All of the formulations shown in Tables 1-8 are balanced with base oil with no lubricant additives added. It is expected that the formulations disclosed herein will have compatible or improved performance and properties with the addition of lubricant additives.

The low temperature flow pressure data in Tables 1 and 2 are generated according to DIN 51805 Kesternich method at negative 20 degree Celsius (° C.). These data demonstrate that the inclusion of high levels of calcium carbonate does not have significant negative impacts on the low temperature flow pressure performance. In fact, the low temperature flow pressure performance is improved by the inclusion of high-level calcium carbonate in the grease formulation.

Based on data shown in Tables 1 and 2, in one embodiment, the lubricating grease may be formulated with calcium sulfonate lower than about 35 wt. % (e.g., 0.1 wt. %-34.9 wt. %) or excluding calcium sulfonate and still achieves Kesternich flow pressure at −20° C. of about 450 mbar or higher, or about 850 mbar or higher. In another embodiment, the lubricating grease may be formulated with calcium 12-HSA lower than about 14.5 wt. % (e.g., about 0.1 wt. %-14.4 wt. %) or excluding calcium 12-HSA and still achieves Kesternich flow pressure at −20° C. of about 850 mbar or higher. In one embodiment, the lubricating grease may include calcium sulfonate about 0 wt. %-15 wt. %, calcium carbonate about 50 wt. %-70 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the Kesternich flow pressure at −20° C. is at least about 425 mbar-850 mbar. In one embodiment, the lubricating grease may include calcium 12-HSA about 0 wt. %-15 wt. %, calcium carbonate about 0 wt. %-38 wt. % or about 50 wt. %-70 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the Kesternich flow pressure at −20° C. is about 800 mbar or higher or about 850 mbar.

The data in Tables 3 and 4 are generated according to ASTM D4049 standard method to evaluate the ability of a grease to adhere to a metal surface when subjected to direct water spray. The data are obtained based on water temperature of 38° C., water pressure of 40 pounds per square inch (psi), spray duration of 5 minutes, and the results are shown in terms of % grease mass loss from the test panel.

The data generated via ASTM D4049 show varied behavior across the material types. Calcium sulfonate grease has a high inherent resistance to water spray (e.g., 15.9% loss). This property is diminished (e.g., 69.2% loss, 39.3% loss, 20.52% loss) at modest loadings of calcium carbonate but is improved (e.g., 9.6% loss) at very high loadings. The calcium 12-HSA grease demonstrates a stepwise improvement in resistance to water spray as a function of calcium carbonate level (e.g., % loss decreases from 79% loss to 50.8% loss).

Based on data shown in Tables 3 and 4, in one embodiment, the lubricating grease may be formulated with calcium sulfonate lower than about 25 wt. % (e.g., 0.1 wt. %-24.9 wt. %) and calcium carbonate of about 25 wt. %-50 wt. % and still achieves excellent grease adhesion with less than about 40% loss. In another embodiment, the lubricating grease may be formulated with calcium 12-HSA lower than about 8 wt. % (e.g., about 7.9 wt. %-0.1 wt. %) and calcium carbonate of about 37 wt. %-50 wt. % and still achieves excellent grease adhesion with about or less than 50% loss. In one embodiment, the lubricating grease may include calcium sulfonate about 0 wt. %-25 wt. %, calcium carbonate about 25 wt. %-50 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the resistance to water spray off according to ASTM D4049 (based on water temperature of 38° C., water pressure of 40 psi, spray duration of 5 minutes) is less than 40% loss or about 9% loss-40% loss. In one embodiment, the lubricating grease may include calcium 12-HSA about 5 wt. %-8 wt. %, calcium carbonate about 35 wt. %-50 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the resistance to water spray off according to ASTM D4049 (based on water temperature of 38° C., water pressure of 40 psi, spray duration of 5 minutes) is less than or about 50% loss.

The four ball extreme pressure data in Tables 5 and 6 are generated according to ASTM D2596 standard test method for measurement of extreme pressure properties of lubricating grease (four-ball method).

These data show the effect of the calcium carbonate inclusion on extreme pressure protection properties. In the calcium sulfonate—calcium carbonate grease, there is a maximum benefit (e.g., >800 kilograms-force or kgf) observed at moderate levels of calcium carbonate (e.g., about 25 wt. %). This diminishes at higher calcium carbonate levels but still exceeds the performance of the calcium sulfonate grease without calcium carbonate. A similar trend is observed with the calcium 12-HSA-calcium carbonate grease, with a maximum observed at 37.5 wt. % calcium carbonate that diminishes as the calcium carbonate loading increases, yet still exceeds the performance of the calcium 12-HSA grease without calcium carbonate.

Based on data shown in Tables 5 and 6, in one embodiment, the lubricating grease may be formulated with calcium sulfonate lower than about 30 wt. % (e.g., 0 wt. %-29.9 wt. %) and calcium carbonate of about 12.5 wt. %-67 wt. % and still achieves excellent extreme pressure protection properties with weld load of at least 500 kgf. In another embodiment, the lubricating grease may be formulated with calcium 12-HSA lower than about 12.2 wt. % (e.g., about 0 wt. %-12.2 wt. %) and calcium carbonate of about 12.5 wt. %-67 wt. % and still achieves excellent extreme pressure protection properties with weld load of at least 400 kgf. In one embodiment, the lubricating grease may include calcium sulfonate about 0 wt. %-30 wt. %, calcium carbonate about 12 wt. %-70 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the weld load is at least about or greater than 500 kgf, about 500 kgf-800 kgf, about 620 kgf-800 kgf, or at least about or greater than 800 kgf. In one embodiment, the lubricating grease may include calcium 12-HSA about 0 wt. %-12 wt. %, calcium carbonate about 12 wt. %-70 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the weld load is at least about or greater than 400 kgf, about 500 kgf-800 kgf, about 500 kgf-800 kgf, about 620 kgf-800 kgf, or at least about or greater than 800 kgf.

The SRV extreme pressure data in Tables 7 and 8 are generated according to ASTM D5706 standard test method for determining extreme pressure properties of lubricating greases using a high-frequency, linear-oscillation (SRV) test machine.

The data generated via ASTM D5706 evaluates the extreme pressure protection qualities of the greases in reciprocating contact conditions. In the calcium sulfonate—calcium carbonate grease, the presence of moderate levels of calcium carbonate greatly improves the pass load capabilities of the grease. As the content of calcium carbonate increases, the pass load peaks around 1400 Newton (N) and 2000 N and diminishes but still exceeds what is observed in the grease without calcium carbonate. In the calcium 12—HSA-calcium carbonate grease, the presence of calcium carbonate improves the performance in a stepwise manner with higher loadings of calcium carbonate.

Based on data shown in Tables 7 and 8, in one embodiment, the lubricating grease may be formulated with calcium sulfonate lower than about 20 wt. % (e.g., 0 wt. %-19.9 wt. %) and calcium carbonate of about 37.5 wt. %-67 wt. % and still achieves excellent extreme pressure protection properties with a pass load of at least 500 N. In another embodiment, the lubricating grease may be formulated with calcium 12-HSA lower than about 12.2 wt. % (e.g., about 0 wt. %-12.2 wt. %) and calcium carbonate of about 12.5 wt. %-67 wt. % and still achieves excellent extreme pressure protection properties with a pass load of at least 500 N.

In one embodiment, the lubricating grease may include calcium sulfonate about 0 wt. %-20 wt. %, calcium carbonate about 35 wt. %-70 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the pass load is at least about or greater than 500 N-2000 N, about 1000 N-about 2000 N, about 1400 N-2000 N, or at least about or greater than 2000 N. In one embodiment, the lubricating grease may include calcium 12-HSA about 0 wt. %-15 wt. %, calcium carbonate about 12 wt. %-70 wt. %, a balanced amount of base oil, and optionally a balanced amount of additives, and the pass load is at least about or greater than 500 N-2000 N, about 800 N-about 2000 N, about 1400 N-2000 N, or at least about or greater than 2000 N.

Although not included in the formulations discussed in Tables 1-8, lubricant additives can be included in the grease formulations discussed herein. The inclusion of lubricant additives is expected to further improve the performance and properties. Calcium carbonates when used at a balanced combination with lubricant additives, such as Zinc dialkyldithiophosphate (ZDDP), show synergistic effects including improved tribological properties, extreme pressure properties in particular. Conventionally, ZDDP is usually used as anti-wear agent, not necessarily an extreme pressure agent. ZDDP when used alone cannot provide the synergistic extreme pressure properties.

The synergistic effects are also seen when the selected calcium carbonates are used at balanced combinations with lubricant other additives, for example, various dialkyldithiocabamates, amine phosphates, amine borate complexes, and others show similar cumulative effects in conjunction with the calcium carbonate. Specifically, the antiwear and/or extreme pressure protection behaviors are improved in combination to an extent greater than when used separately.

Calcium carbonates when used with active sulfur-containing additives, for example, sulfurized isobutylene, polysulfide compounds, and sulfonated fatty acids show anti-synergistic effects with no improvement or slight negative effects on lubricating performance. In some embodiments, the grease formulations in the present disclosure exclude active sulfur-containing additives or the grease formulations in the present disclosure are substantially free of sulfur-containing additives. In some embodiments, sulfurized isobutylene is used in conjunction with other additives selected to improve the grease properties and performance.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the present specification, including definitions, will control.

Unless otherwise specified, “a,” “an,” “the,” “one or more of,” and “at least one” are used interchangeably. The singular forms “a”, “an,” and “the” are inclusive of their plural forms.

The recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 0.1 to 5 includes 0.01, 0.05, 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

The term “about,” when referring to a value or to an amount of mass, weight, time, volume, concentration, or percentage is meant to encompass variations of ±1.5% from the specified amount. The terms “comprising” and “including” are intended to be equivalent and open-ended. The phrase “consisting essentially of” means that the composition or method may include additional ingredients and/or steps, but only if the additional ingredients and/or steps do not materially alter the basic and novel characteristics of the claimed composition or method. The phrase “selected from the group consisting of” is meant to include mixtures of the listed group.