Corrosion inhibitor and industrial lubricant including the same
Disclosed herein are corrosion inhibitors suitable for heavy-duty industrial lubricants and industrial lubricating compositions including such corrosion inhibitors combined with phosphonate diesters to provide good copper corrosion and roller bearing protection. The corrosion inhibitor has a high content of dialkyl dithiothiadiazole compounds configured to maintain high levels of the phosphonate diester in the lubricant.
1. A corrosion inhibitor made by a process comprising:
(a) reacting a 1,3,4-dimercapto thiadiazole or alkali metal salt thereof with an alkyl mercaptan in the presence of an acid to form a first reaction intermediate;
(b) reacting the first reaction intermediate with hydrogen peroxide to form the corrosion inhibitor; and
(c) wherein the 1,3,4-dimercapto thiadiazole or alkali metal salt thereof, the alkyl mercaptan, and the hydrogen peroxide are provided at a molar ratio of 1:1.95-2.15:2.1-2.4.
2. The corrosion inhibitor of claim 1 , wherein the acid is a strong acid provided in molar excess to the 1,3,4-dimercapto thiadiazole.
3. The corrosion inhibitor of claim 1 , wherein the corrosion inhibitor is about 95 mol percent or more of a 2,5-dialkyl-dithiothiadiazole compound and about 5 mol percent or less of a monoalkyl-dithiothiadiazole compound.
4. The corrosion inhibitor of claim 1 , wherein the corrosion inhibitor has a total acid number of 10 or less.
5. The corrosion inhibitor of claim 1 , wherein the process further includes heating the corrosion inhibitor to a temperature effective to separate any aqueous layer and optionally subjecting the heated corrosion inhibitor to a vacuum strip.
6. The corrosion inhibitor of claim 3 , wherein the 2,5-dialkyl-dithiothiadiazole compound has the structure of Formula Ia:
and
wherein the monoalkyl-dithiothiadiazole compound has the structure of Formula Ib:
wherein each R 1 of Formula Ia and/or Formula Ib is independently a linear or branched C4 to C20 hydrocarbyl group.
7. The corrosion inhibitor of claim 1 , wherein the alkyl moiety of the alkyl mercaptan is an aliphatic or aromatic hydrocarbyl group.
8. The corrosion inhibitor of claim 7 , wherein the alkyl moiety of the alkyl mercaptan is a linear or branched C1 to C30 hydrocarbyl group.
9. A lubricant comprising:
(a) a majority of base oil; and
(b) a corrosion inhibitor made by a process comprising:
(i) reacting a 1,3,4-dimercapto thiadiazole or alkali metal salt thereof with an alkyl mercaptan in the presence of an acid to form a first reaction intermediate;
(ii) reacting the first reaction intermediate with hydrogen peroxide to form the corrosion inhibitor; and
(iii) wherein the 1,3,4-dimercapto thiadiazole or alkali metal salt thereof, the alkyl mercaptan, and the hydrogen peroxide are provided at a molar ratio of 1:1.95-2.15:2.1-2.4.
10. The lubricant of claim 9 , wherein the acid is a strong acid provided in molar excess to the 1,3,4-dimercapto thiadiazole.
11. The lubricant of claim 9 , further comprising one or more phosphonate ester compounds including, based on the total weight percent of phosphonate ester compounds, about 90 weight percent or more of a phosphonate diester and no more than about 10 weight percent of a phosphonate monoester.
12. The lubricant of claim 9 , wherein the corrosion inhibitor is about 95 mol percent or more of a 2,5-dialkyl-dithiothiadiazole compound and about 5 mol percent or less of a monoalkyl-dithiothiadiazole compound.
13. The lubricant of claim 12 , wherein the 2,5-dialkyl-dithiothiadiazole compound has the structure of Formula Ia:
and
wherein the monoalkyl-dithiothiadiazole compound has the structure of Formula Ib:
wherein each R 1 of Formula Ia and/or Formula Ib is, independently, a linear or branched C4 to C20 hydrocarbyl group.
14. The lubricant of claim 11 , wherein the phosphonate diester has a structure of Formula II
wherein R 2 is a C 1 to C 50 hydrocarbyl group and each R 3 is, independently, a C 1 to C 20 alkyl group.
15. The lubricant of claim 14 , wherein the phosphonate diester is dimethyl octadecyl phosphonate.
16. The lubricant of claim 11 , wherein the phosphonate monoester has a structure of Formula III
wherein R 4 is a C 1 to C 50 hydrocarbyl group and R 5 is a C 1 to C 20 alkyl group.
17. The lubricant of claim 16 , wherein the phosphonate monoester is methyl octadecyl phosphonate.
18. The lubricant of claim 9 , wherein the process further includes heating the corrosion inhibitor to a temperature effective to separate any aqueous layer and optionally subjecting the heated corrosion inhibitor to a vacuum strip.
19. The lubricant of claim 9 , wherein the lubricant exhibits a FAG FE8 roller bearing weight loss of about 12 mg of less pursuant to DIN 51819-3 after 80 hours of runtime at 80° C., 7.5 rpm, and 100 kN.
20. A corrosion inhibitor additive comprising:
(a) about 95 mol percent or more of a 2,5-dialkyl-dithiothiadiazole compound;
(b) a monoalkyl-dithiothiadiazole compound, but no more than about 5 mol percent of the monoalkyl-dithiothiadaizole compound; and
(c) wherein the total acid number of the corrosion inhibitor additive is about 10 or less; and
wherein the corrosion inhibitor is obtained from a dimercapto thiadiazole or alkali metal salt thereof, an alkyl mercaptan, and a hydrogen peroxide provided at a molar ratio of 1:1.95-2.15:2.1-2.4.
21. The corrosion inhibitor of claim 20 , wherein the 2,5-dialkyl-dithiothiadiazole compound has the structure of Formula Ia:
and
wherein the monoalkyl-dithiothiadiazole compound has the structure of Formula Ib:
wherein each R 1 of Formula Ia and/or Formula Ib is independently a linear or branched C4 to C20 hydrocarbyl group.