Composition and method of manufacturing calcium sulfonate greases using alkali metal hydroxide and delayed addition of non-aqueous converting agents
An overbased calcium sulfonate grease composition and method of manufacture comprising added alkali metal hydroxide alone or in combination with (a) calcium hydroxyapatite and/or added calcium carbonate used as calcium containing bases for reacting with complexing acids) and/or (b) at least one delay period between the addition of water as a converting agent and addition of a portion of a non-aqueous converting agent. A delay period may involve the period of time it takes to adjust the temperature of the mixture, a period of time during which the mixture is held at a temperature or within a range of temperatures, and multiples and any combination thereof. These calcium sulfonate greases have improved thickener yield and high dropping points compared to greases made without added alkali metal hydroxide and delay between the additions of water and a non-aqueous converting agent, particularly when a poor quality overbased calcium sulfonate is used.
1. A method for making a complex overbased calcium sulfonate grease comprising the steps of:
mixing an amount of overbased oil-soluble calcium sulfonate having amorphous calcium carbonate dispersed therein with a base oil, and one or more converting agents to form a pre-conversion mixture;
converting the pre-conversion mixture to a converted mixture by heating until conversion of the amorphous calcium carbonate to crystalline calcium carbonate has occurred;
mixing an amount of an alkali metal hydroxide with the pre-conversion mixture, converted mixture or both; and
mixing an amount of one or more complexing acids with the pre-conversion mixture or the converted mixture or both; and
wherein the amount of overbased oil-soluble calcium sulfonate is around 10% to 45%.
2. The method according to claim 1 wherein the amount of alkali metal hydroxide is around 0.005% to 5%.
3. The method according to claim 1 further comprising mixing one or more of calcium hydroxyapatite, added calcium hydroxide, added calcium oxide, added calcium carbonate, or any combination thereof with the pre-conversion mixture, converted mixture or both.
4. The method according to claim 1 wherein the alkali metal hydroxide is sodium hydroxide, lithium hydroxide, potassium hydroxide or a combination thereof.
5. The method according to claim 2 wherein the alkali metal hydroxide is sodium hydroxide and the amount of sodium hydroxide mixes is around 0.01% to 0.4%.
6. The method according to claim 1 wherein the alkali metal hydroxide is dissolved in water to form a solution and the solution is mixed with the pre-conversion mixture, converted mixture or both.
7. The method according to claim 1 wherein the overbased calcium sulfonate is a poor quality calcium sulfonate and the grease has a dropping point of at least 575 F.
8. The method according to claim 1 wherein the converting agents comprise water and one or more non-aqueous converting agents and the method further comprises:
mixing the water with the overbased calcium sulfonate and base oil to form a first mixture;
mixing at least a portion of the one or more non-aqueous converting agents with the first mixture during or after one or more delay periods to form the pre-conversion mixture.
9. The method according to claim 8 wherein the alkali metal hydroxide is dissolved in the water used as a converting agent to form a solution and the solution is mixed with the overbased calcium sulfonate and base oil to form the first mixture.
10. The method according to claim 8 wherein the alkali metal hydroxide is dissolved in a second portion of water to form a solution and the solution is mixed with the first mixture, the pre-conversion mixture, the converted mixture, or a combination thereof.
11. The method according to claim 8 wherein at least all or a portion of one complexing acid is mixed with the first mixture or pre-conversion mixture and at least all or a portion of the same or a different complexing acid is mixed with the converted mixture.
12. The method according to claim 11 wherein at least a portion of one complexing acid is mixed with the first mixture or the pre-conversion mixture prior to any heating.
13. The method according to claim 8 wherein the converting step comprises:
heating the pre-conversion mixture to a conversion temperature range of about 190 F to 230 F for an open vessel or other temperature range at which conversion occurs for a closed vessel; and
maintaining the temperature in that range until conversion of the amorphous calcium carbonate to crystalline calcium carbonate has occurred.
14. The method according to claim 11 wherein the complexing acids comprise acetic acid and 12-hydroxystearic acid and wherein a portion of both acids is mixed with the first mixture or the pre-conversion mixture and another potion of both acids is mixed with the converted mixture.
15. The method according to claim 14 wherein the complexing acids further comprise boric acid, phosphoric acid, or both and wherein all of the boric acid, phosphoric acid or both are mixed with the converted mixture.
16. The method according to claim 14 wherein the non-aqueous converting agent is hexylene glycol and it is mixed with the first mixture after a temperature adjustment delay period.
17. The method according to claim 14 wherein the alkali metal hydroxide is mixed with the first mixture.
18. The method of claim 1 wherein the calcium sulfonate grease has a dropping point of at least 575 F and the amount of overbased calcium sulfonate is around 10% to 32%.
19. The method of claim 8 wherein the calcium sulfonate grease has a dropping point of at least 575 F and the amount of overbased calcium sulfonate is around 10% to 32%.
20. The method according to claim 8 further comprising adding at least a portion of one or more of the non-aqueous converting agents to one or more of the following: the first mixture before any delay period, the first mixture during or after a delay period, or the pre-conversion mixture during or after one or more delay periods.
21. The method according to claim 20 wherein acetic acid is not added as a non-aqueous converting agent during any delay period.
22. The method according to claim 8 further comprising mixing one or more of calcium hydroxyapatite, added calcium hydroxide, added calcium oxide, added calcium carbonate, or any combination thereof with the first mixture, the pre-conversion mixture, the converted mixture or any combination thereof.
23. The method according to claim 8 wherein at least one of the non-aqueous converting agents is a glycol, a glycol ether, or a glycol polyether.
24. The method according to claim 20 wherein the glycol is hexylene glycol.
25. The method according to claim 24 wherein a portion of the hexylene glycol is mixed with the first mixture prior to any delay period and another portion of the hexylene glycol is mixed to the first mixture or pre-conversion mixture after or during one or more delay periods.
26. The method according to claim 8 wherein there are at least two delay periods, wherein one of the delay periods is a temperature adjustment delay period where the first mixture or pre-conversion mixture is heated or cooled and at least one other delay period is a holding delay period wherein the first mixture or pre-conversion mixture is maintained at a temperature or within a range of temperatures for a period of time.
27. The method according to claim 8 wherein the overbased calcium sulfonate is a poor quality overbased calcium sulfonate.
28. The method according to claim 22 wherein the overbased calcium sulfonate comprises around 0% to 8% residual calcium hydroxide and/or calcium oxide and wherein no additional calcium oxide or calcium hydroxide is added as a calcium containing base for reacting with complexing acids.
29. The method according to claim 8 wherein at least one of the non-aqueous converting agents is methanol, isopropyl alcohol, or another low molecular weight alcohols.
30. The method according to claim 8 wherein methanol, isopropyl alcohol, or another low molecular weight alcohol is not used as a non-aqueous converting agent.
31. The method according to claim 1 wherein the amount of overbased calcium sulfonate is around 10% to 22%.
32. The method of claim 1 wherein at least a portion of the alkali metal hydroxide is added to the pre-conversion mixture.
33. The method of claim 1 further comprising mixing one or more of calcium containing bases for reaction with the one or more complexing acids;
wherein the one or more calcium containing bases are added to the pre-conversion mixture, the converted mixture, or both; and
wherein at least a portion of the alkali metal hydroxide is added prior to the reaction between the one or more calcium containing bases and the one or more complexing acids.
34. The method of claim 1 further comprising mixing one or more of calcium containing bases for reaction with the one or more complexing acids;
wherein the one or more calcium containing bases are added to the pre-conversion mixture, the converted mixture, or both; and
wherein at least a portion of the one or more calcium containing bases and at least a portion of the one or more complexing acids are added and mixed after mixing at least a portion of the alkali metal hydroxide.
35. The method of claim 1 wherein at least a portion of the alkali metal hydroxide is added to the pre-conversion mixture and at least a portion of the same or a different alkali metal hydroxide is added to the converted mixture.