High performance grease compositions

Abstract

This invention relates to overbased calcium sulfonate complex grease compositions prepared without boric acid and alcohol promotors containing anti-wear, anti-friction, thermal & oxidation stability additives.

Claims

1. A method for making a high performance overbased calcium sulfonate complex grease composition prepared without boric acid and without the use of any alcohol-based promotors comprising reacting and mixing (a) a primary overbasing material comprising overbased oil-soluble calcium sulfonate having amorphous calcium carbonate dispersed therein; (b) a suitable base oil of an amount appropriate to provide a final acceptable product consistency; (c) in the presence of a functionalized polymer, a stoichiometric excess of finely divided calcium carbonate as an oil-insoluble solid calcium containing base added to the primary overbasing material and base oil before conversion; and (d) a doping agent in the form of an extreme-pressure, anti-wear, antioxidant, metal deactivator or polymeric additive, or combination thereof wherein the mixture is heated at a rate of less than 1 C. per minute to a temperature of 45-50 C.

2. The method of claim 1, further comprising the addition of a carboxylic acid between steps (c) and (d) selected from the group consisting of a long chain aliphatic carboxylic acid with at least 12 carbon atoms.

3. The method of claim 2 wherein the amount of overbased oil-soluble calcium sulfonate is between 10 and 35% by weight.

4. The method of claim 3, wherein the amount of the overbased oil-soluble calcium sulfonate is between 18 and 25% by weight.

5. The method of claim 4, wherein the total amount of base oil added is between 25% and 80% by weight.

6. The method of claim 5, wherein the total amount of base oil added is between 35% and 75% by weight.

7. The method of claim 6, wherein the total amount of base oil added is between 40% and 70% by weight.

8. The method of claim 5, wherein the amount of long chain carboxylic acid is between 1% and 6% by weight.

9. The method of claim 8, wherein the amount of long chain carboxylic acid is between 2.0% and 3.5% by weight.

10. The method of claim 8, wherein the amount of doping agent is between 0.5-15% by weight.

11. The method of claim 10, wherein the amount of doping agent is between 5-12% by weight.

12. The method of claim 10 wherein the resulting grease composition contains an insoluble portion of crystalline capsule morphology.

13. The method of claim 12, wherein the crystalline capsule morphology has a length of about 16.4+/6.4 nm and a width of about 5.7+/1.3 nm.

14. The method of claim 1, further comprising increasing the temperature to 9010 C.; raising the temperature to 16010 C.; and cooling to 11010 C.

15. The method of claim 1, further comprising adding an anionic surfactant selected from the group consisting of a hydrophilic sulfonate head-group and a hydrophobic alkylbenzene tail-group.

16. The method of claim 15, wherein the anionic surfactant is alkyl benzene sulfonic acid.

17. The method of claim 12, wherein the grease composition has a weld load of at least 800 kgs according to ASTM D2596.

18. The method of claim 12, wherein the grease composition has a high temperature life greater than 280 hours according to ASTM D3527.

19. A grease composition comprising the reaction product made from components which comprise: (a) an overbased oil-soluble calcium sulfonate having amorphous calcium carbonate dispersed therein present in an amount of 18-25 weight percent; (b) a base oil present in an amount of 40-70 weight percent; (c) a functionalized polymer that acts as a binding medium between the overbased calcium sulfonate and base oil; (d) a long chain carboxylic acid having at least 12 carbon atoms present in an amount of 2.0-3.5 weight percent; (e) acetic acid present in an amount of 0.5-1.0 weight percent; (f) an anionic surfactant comprising a hydrophilic sulfonate head-group and a hydrophobic alkylbenzene tail-group; and (g) a doping agent selected from the group consisting of extreme-pressure additives, anti-wear additives, antioxidants, metal deactivators, polymeric additives, and combinations thereof present in an amount of 5-12 weight percent; wherein the grease composition comprises an insoluble portion having crystalline capsule morphology with a length of 16.4+/6.4 nm and a width of 5.7+/1.3 nm, and wherein the grease composition exhibits a weld load of at least 800 kgs according to ASTM D2596 and a high temperature life greater than 280 hours according to ASTM D3527.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a comparative graph of extreme pressure Weld load overbased Ca-sulfonate complex greases with Lithium complex and OBCSC greases described herein.

(2) FIG. 2 is a comparative graph of extreme pressure Timken OK Load overbased Ca-sulfonate complex greases with Lithium complex and OBCSC greases described herein.

(3) FIG. 3 is a comparative graph of high temperature life of overbased Ca-sulfonate complex greases with Lithium complex and OBCSC greases.

(4) FIG. 4 is a photo of the crystalline capsule morphology of the grease as described herein.

(5) FIG. 5 is a photo of the crystalline needle morphology of a grease within the state of the art.

DESCRIPTION OF THE INVENTION

(6) Herein is described overbased an calcium sulfonate complex grease that has been prepared without traditional formation steps utilizing boric acid and/or the use of any alcohol-based promotors thus simplifying the manufacturing process.

(7) According to one embodiment of the invention, this overbased grease is produced by reacting and mixing certain compounds comprising: (a) a primary overbasing material comprising overbased oil-soluble calcium sulfonate having amorphous calcium carbonate dispersed therein; (b) a suitable base oil of an amount appropriate to provide a final acceptable product consistency; (c) in the presence of a functionalized polymer, a stoichiometric excess of finely divided calcium carbonate as an oil-insoluble solid calcium-containing base added to the primary overbasing material and base oil before conversion along; and (d) a doping agent in the form of an extreme-pressure, anti-wear, antioxidant, metal deactivator or polymeric additive, or combination thereof.

(8) A further embodiment of the invention is the presence of crystalline, capsular morphologies in the resultant insoluble portion of the grease composition from the method as described herein. The capsule morphology consistent with the invention as described herein has a length of 16.4+/6.4 nm and a width of 5.7+/1.3 nm. The presence of the capsule morphologies within the grease composition described herein are distinct and distinguished from the state of the art and have associated beneficial properties in relevant pressure and temperature environments over comparative high performance lithium complex and conventional overbased Ca-sulfonate complex greases, see Table 2 and FIGS. 1-3.

(9) The highly overbased oil-soluble calcium sulfonate used according to an embodiment of the invention can be any typical to that documented in the prior art, such as U.S. Pat. Nos. 4,560,489; 5,126,062; 5,308,514; 5,338,467 and EP 2773590A1. The highly overbased oil-soluble calcium sulfonate may be produced in situ according to such known methods or may be purchased as a commercially available product. Such highly overbased oil-soluble calcium sulfonates will have a Total Base Number (TBN) value not lower than 200, preferably not lower than 300, and most preferably about 400. Commercially available overbased calcium sulfonates of this type include, but are not limited to, the following: Hybase C401 as supplied by Chemtura USA Corporation; Syncal OB 400 and Syncal OB405-WO as supplied by Kimes Technologies International Corporation; Lubrizol 75GR, Lubrizol 75NS, Lubrizol 75P, and Lubrizol 75WO as supplied by Lubrizol Corporation. The amount of the highly overbased oil-soluble calcium sulfonate in the final grease according to this embodiment of the invention can vary but is generally between 10 and 35%. Preferably, the amount of the highly overbased oil-soluble calcium sulfonate in the final grease according to an embodiment of the invention is between 18 and 25%.

(10) Any petroleum-based naphthenic, paraffinic mineral oils or renewable base oils commonly used and well known in the grease making art may be used as the base oil according to the invention. Synthetic base oils may also be used in the greases of the present invention. Such synthetic base oils include but not limited to polyalphaolefins (PAO), diesters, polyol esters, polyethers, alkylated benzenes, alkylated naphthalenes, and silicone fluids. Renewable base oils possessing properties as described in U.S. Pat. No. 11,041,133 herein incorporated by reference are preferred. The total amount of base oil added, including that initially added and any that may be added later in the grease process to achieve the desired consistency, will typically be between 25% and 80%, preferably 35% and 75%, most preferably 40% and 70%, based on the final weight of the grease.

(11) Complexing acids used in this embodiment will comprise no boric acid but will contain at least one long chain carboxylic acid and may comprise a short chain carboxylic acid. The long chain carboxylic acids suitable for use in accordance with the invention comprise aliphatic carboxylic acids with at least 12 carbon atoms. Most preferably, the long chain carboxylic acid is 12-hydroxystearic acid. The amount of long chain carboxylic acid is between 1% and 6%, preferably 1% to 5%, most preferably 2.0% to 3.5%, based on the final weight of the grease.

(12) Functionalized polymer as used herein is defined as a polymer which functions to act as binding medium between overbased calcium sulfonate complex thickener and base oil over entire reaction cycle. A functionalized polymer may include but not limited to those described in U.S. Pat. No. 8,563,488, herein incorporated by reference.

(13) The doping agent comprising an oxidation inhibitor, antiwear additive, metal deactivator, and pressure additive will typically be between 0.5-15% and preferably 5-12% based on the total weight of the grease.

(14) Method of Making the Grease Composition

(15) An embodiment of the invention for making the grease composition with amounts and terminology reflected in Table 1. is described herein. Overbased natural/Synthetic calcium sulfonate is added to a base oil at room temperature with sequential addition of calcium hydroxide, calcium carbonate, water and a functionalized polymer to form an initial mixture. The resulting mixture is heated slowly (<1 deg C./minute) to a temperature of 45-50 C.

(16) An anionic surfactant is added when the mixture reaches the aforementioned temperature range to form a second mixture. The anionic surfactant is preferably selected from the group consisting of a hydrophilic sulfonate head-group and a hydrophobic alkylbenzene tail-group. More preferably, the anionic surfactant is alkyl benzene sulfonic acid. At a temperature less than 65 C., 0.25-3.5% acetic acid is gradually added to the second composition to form a third mixture. After 15-30 minutes of hold time, the temperature of the third mixture is increased to 9010 C. A full quantity, 1.0-4.5% kg, of 12-hydroxy stearic acid is added to the heated third mixture to form a fourth mixture wherein an additional amount of water is added.

(17) The temperature of the fourth mixture is raised to 16010 C. with subsequent addition of a hydrogenated styrene isoprene polymer to form a fifth mixture that is mixed for 30-60 minutes at the raised temperature.

(18) The fifth mixture is cooled to a temperature of 11010 C. by adding a portion of finish base oils to form a sixth mixture, with the sequential addition of remaining calcium carbonate and tricalcium phosphate to form a seventh mixture. Upon formation of the seventh mixture the crystalline capsule morphology as described herein is presented.

(19) The remainder of additives are added to the seventh mixture at a temperature less than or equal to 100 C., wherein the resulting grease composition is milled to a desired specification.

(20) TABLE-US-00001 TABLE 1 Example Grease Composition Ca-Sulfonate Ca-Sulfonate Complex Composition Complex Preferred Range Composition Raw Material or Additive Weight % % Range 400 TBN Overbased natural/ 18.00-25.00 10.00-35.00 Synthetic calcium sulfonate Calcium hydroxide 1.50-2.50 1.00-3.00 Calcium carbonate 3.00-5.00 1.00-10.00 Water 5.00-7.00 3.00-12.00 Functionalized Polymer 0.20-0.50 0.1-1.00 Alkyl Benzene Sulfonic Acid 2.00-3.50 1.00-5.00 Acetic Acid 0.50-1.00 0.25-1.50 12 Hydroxy stearic acid 2.00-3.50 1.50 5.00 hydrogenated styrene 0.50-1.50 0.50-2.50 isoprene polymer Tricalcium phosphate 1.50-3.50 1.00-5.00 Substituted diarylamine 0.50-1.50 0.50-2.50 oxidation inhibitor Ashless EP and antiwear 1.50-3.50 1.00-5.00 Additive Proprietary Extreme Pressure 1.00-3.00 1.00-5.00 additive MoS2 0.0-5.00 0.0-5.00 Metal Deactivator 0.1-0.50 0.05-1.00 Base oil (Mineral, renewable, Balance Oil 40.00-70.00 Synthetic and/or blend)

(21) The performance data specially in terms of extreme-pressure, and high temperature have been compared with conventional fully formulated lithium complex EP (extreme pressure) and fully formulated Ca-sulfonate complex greases, Table 2. Comparative data (FIG. 1-3) indicate their superior comparative performance data compared to high performance lithium complex and overbased Ca-sulfonate complex greases indicating potentially synergistic effect of unique combination of composition, additives and process.

(22) TABLE-US-00002 TABLE 2 Comparative Test Data of an OBCSC composition embodiment of the invention with conventional Lithium complex and Ca-sulfonate greases. Weld Load Timken OK High temperature (kgs) Load (lbs) life (hrs) Test Method ASTM ASTM ASTM Greases D2596 D2509 D3527 NLGI GC-LB 200 N/A 80 NLGI HPM 250 N/A N/A NLGI HPM-High Load 400 N/A N/A Li-com (C) GR-1 250 40 26.67 LI-com (C) GR-2 225 20 53.33 Li-com (C) GR-3 250 40 100 Li-com (I) GR-4 325 70 170 Li-com (I) GR-5 400 80 180 Li-com (I) GR-6 400 80 290 Li-com (I) GR-7 400 70 100 Ca-sulfonate (C) 565 60 150 GR-8 Ca-sulfonate (C) 615 60 60.3 GR-9 Ca-sulfonate (C) 345 60 140.3 GR-10 Ca-sulfonate (C) 340 50 60 GR-11 CVX-OBCSC (VG460) 800 65 280 CVX-OBCSC (VG460 800 75 339 5% Moly) CVX-OBCSC (VG220) 800 80 305