US3398095A - Vapor-space inhibitors - Google Patents

Description

United States Patent 3,398,095 VAPOR-SPACE INHIBITORS Clark W. Judd, Alton, Ill., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 13, 1967, Ser. No. 682,571 16 Claims. (Cl. 25247.5)

ABSTRACT OF THE DISCLOSURE The corrosion prevention characteristics of volatile vapor-space inhibitors are greatly enhanced by the presence of sulfurized oleic acid together with a member selected from (1) a C C n-alkyl carboxylic acid and (2) a C -C n-alkyl carboxylic acid and certain amines.

BACKGROUND OF THE INVENTION This invention relates to antirust lubricant compositions and particularly to an antirust composition comprising sulfurized carboxylic acid with conventional vapor-space inhibitors such as fatty acids and alkyl or cyclic amines.

It is well known that the rusting of ferrous metal surfaces is a common problem in the field of lubrication. Accordingly, a large amount of research effort has developed a great many additives which, when present in lubricants in small amounts, inhibit corrosion of the surfaces with which the oil comes into contact. Reference to many of these inhibitors is found in a book by Putilova et al., Metallic Corrosion Inhibitors, Pergamon Press, 1960. Although these known inhibitors are successful in reducing or eliminating corrosion of metal in contact wtih the liquid, they are generally ineffective for reducing corrosion in the vapor space above the fluid. These preservative oils are adequate only "as long as a continuous oil film of appreciable thickness is maintained. However, serious rusting problems have been encountered in certain infrequently operated or stored equipment, especially when the humidity is high. For instance, a large amount of agricultural machinery is in operation only during certain seasons of the year. F-rui-t picking and packing equipment may be idle for most of the year; for example, processing equipment in a winery may be in operation only a few weeks annually. Snow removal equipment must be in storage throughout the summer. Both new and used cars may remain for months in dealers lots with infrequent operation. It is apparent that although known inhibitors would prevent rusting of the metal surfaces in contact with the lubricating oil, corrosion could occur freely in the space above the oil level.

To prevent corrosion in the vapor space, it is generally necessary to include certain organic compounds known as vapor-space inhibitors. Effective vapor-space inhibitors are well known and, in general, include certain fatty acids and amines, alone or in combination, with each other. Effective as these vapor-space inhibitors may be, improvement is desired.

SUMMARY It has now been discovered that oils containing sulfurized carboxylic acid in combination with known vapor-space inhibitors such as the fatty acids and amines provide excellent corrosion inhibition for ferrous metals not in contact with the fluid lubricant. The inhibitor combination may be incorporated into formulations which are used as steam-turbine oils, hydraulic and circulating oils, factory-fill fuels and lubricants, general preservative oils, greases, and the like. The combination is highly effective for preventing vapor-space corrosion in systems where water may be present in the oil.

I Patented Aug. 20, 1968 DESCRIPTION OF THE PREFERRED EMBODIMENTS The inhibitor combination may be used in a variety of lubricants. Preferably the lubricant is a mineral oil, such as that used in formulating turbine oil, circulating oil, hydraulic fluids, etc. Typical properties of a suitable mineral oil for use in the invention are:

GR, API, 60 C. 25.3 Pour point, F. 20 Flash, F. COC 460 Viscosity:

SUS at F. 533 SUS at 210 F. 65.5 Viscosity index 97 The fatty acids suitable for use in the inhibitor combination are those used as conventional vapor-space inhibitor agents and are preferably C to C n-alkylcarboxylic acids. Of these acids, caprylic, pelargonic and capric are particularly preferred.

Alkylcarboxylic acids, such as pelargonic acid, are very effective oil-soluble vapor-space inhibitors by themselves in neutral and acidic systems. However, the effectiveness of such an inhibitor can be extended to basic systems, as well as improved, by adding to the acid an amine.

Amines suitable for use in the present compositions are those conventionally used as vapor-space inhibitors and include primary, and secondary tertiary alkyl and cycloalklyl amines and other cyclic amines. In general, the amines contain from 4 to 18 carbon atoms. Amines which are preferred for use in the inhibitor combination of the present invention are hexylamine, cyclohexylamine, dicyclohexylamine, N,N-dimethyl 1,3 propane dia mine, morpholine, tri-n-butylamine, piperidine and N,N-dimethly piperazine.

Suitable sulfurized carboxylic acids include the sulfurized acids derived from C to C unsaturated hydrocarbon carboxylic acids and preferably sulfurized fatty acids. Preferred are sulfurized fatty acids having from 12. to 18 carbon atoms, and particularly sulfurized oleic, linoleic acid and the like. Mixtures of the above acids may also be used. The preferred sulfurized acids are those derived from oleic acid or a mixture of olefinic acids which is predominantly oleic acid, viz. commercial grades of oleic acid.

The preparation of sulfurized fatty acids is well known and can be achieved simply by reacting the unsaturated acid, e.g., oleic acid, with free sulfur at temperatures of about C. to 300 C. The amount of sulfur in the sulfurized acid may vary from about 5 to 15% w. Sulfurized oleic acid available commercially from Carlisle Chemical Works.

The concentration of the amine, alkylcarboxylic acid and sulfurized olefinic acid, based on the total formulation can vary over wide ranges. Oil formulations containing .concentrations ranging from 0.01 to 1.0% sulfurized carboxylic acid 0.05 to 0.5% alkylcarboxylic acid and 0.1 to 0.5% amine, if present, are quite suitable. For example, 0.03% w. sulfurized oleic acid plus 0.1% w. pelargonic acid and 0.2% w. dicyclohexylamine, are

satisfactory to provide effective VSI properties in circulating oils. Doubling the concentrations ofthe respective compounds in circulating oil formulations does not noticeably change the vapor space inhibitor properties of the oil.

Other additives may also be added to the oil formulations of the present invention containing the inhibitor combination to improve its performance. These additives include, for example, antifoam agents, oxidation inhibitors, such as hindred phenols and aromatic amines, dispersants, pour point depressants, extreme pressure agents, liquid phase rust inhibitors, such as C2042 alkyl succinic acids, and viscosity improvers.

Illustrative examples of formulations according to the invention comprise.

Composition A: Percent w. Sulfurized oleic acid 0.02 Dicyclohexylamine 0.2 Pelargonic acid 0.1 C2042 alkyl succinic acid 0.03 Mineral lubricating oil, balance.

Composition B:

Sulfurized linoleic acid 0.03 Dicyclohexylamine 0.15 Pelargonic acid 0.13 C2042 alkyl succinic acid 0.01 Mineral lubricating oil, balance.

Composition C:

Sulfurized linoleic acid 0.02

Dicyclohexylamine 0.25 Caprylic acid 0.15 C2042 alkyl succinic acid 0.05 Mineral lubricating oil, balance.

Composition D:

Sulfurized oleic acid 0.02

Dicyclohexylamine 0.20 Capric acid 0.10 C2042 alkyl succinic acid 0.1 Mineral lubricating oil, balance.

Composition E:

Sulfurized oleic acid 0.02 Morpholine 0.20 Pelargonic acid 0.15 C2042 alkyl succinic acid 0.03 Mineral lubricating oil, balance.

Composition F:

Sulfurized oleic acid 0.04 Piperidine 0.25 Pelargonic acid 0.12

Mineral lubricating oil, balance.

CompositionzG:

Sulfurized oleic acid 0.02 Hexylamine 0.20 Pelargonic acid 0.10

Mineral lubricating oil, balance.

Composition H:

Sulfurized oleic acid 0.02 Dicyclohexylamine 0.20 Pelargonic acid 0.10 C2042 alkyl succinic acid 0.03 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

Composition J:

Sulfurized oleic acid 0.02 Dicyclohexylamine 0.20 Caprylic acid 0.10 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

To illustrate the effectiveness of the inhibitor combination in compositions of the present invention with respect to vapor-space inhibitor (VSI) properties, a comparison is made with the following compositions:

Composition K: Percent w. Dicyclohexylamine 0.20 Pelargonic acid 0.10 C2042 alkyl succinic acid 0.03 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

Composition L:

Sulfurized oleic acid 0.02 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50 Mineral lubricating oil, balance.

Composition M:

Sulfurized oleic acid 0.02 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50 Pelargonic acid 0.05 Heptanoic acid 0.05 Mineral lubricating oil, balance.

Composition N:

Sulfurized oleic acid 0.02 Dicyclohexylamine 0.20 C2042 alkyl succinic acid 0.03 Phenyl-alpha-naphthylamine 0.10 2,6-di-t-butyl-4-methyl phenol 0.50

Mineral lubricating oil, balance.

To test the eflectiveness of the vapor-space inhibitor agents in the various compositions, the compositions Were subjected to a F. corrosion test. This test consists of suspending a freshly polished and cleaned mild steel block, 1.8 cm. x 1.8 cm. x 0.6 cm., in the upper portion of a 250 ml. Erlenmeyer flask from a watch glass which covers the flask. 5 ml. of the oil composition to be tested and 10 ml. distilled Water are placed in the flask. The flask is immersed in an oil bath at 150 F. to a depth of 5 cm. The steel block was examined after 7 days; if there were 6 specks or more of rust, the oil composition was considered to have failed the test. Compositions H, J, K, L, M and N were tested. The results of these tests are given in Table 1.

TABLE 1 Composition Run No. Result 1 Pass 1 Do. 1 Fail 1 Do. 1 Pass 1 Fail.

The results of Table 1 show that the compositions of the present invention possessed satisfactory vapor-space inhibitor properties (Compositions H and I), whereas compositions in which the sulfurized oleic acid, amine and/or alkylcarboxylic acid was omitted, did not have satisfactory vapor-space inhibitor properties.

I claim as my invention:

1. A lubricating oil composition comprising a major amount of a lubricating oil and a minor amount, sufficient to impart vapor-space inhibiting properties, of a vaporspace inhibitor consisting of a sulfurized C unsaturated carboxylic acid and a member selected from the group consisting of (1) a C n-alkylcarboxylic acid and (2) a C C n-alkylcarboxylic acid and an amine selected from the group consisting of alkylamines cycloalkylamines, morpholine, piperidine and N, N-dimethyl piperazine.

2. The composition of claim 1 wherein the vapor space inhibitor consists of 0.01 to 1.0% of a sulfurized C 5 unsaturated carboxylic acid, 0.05 to 0.5% of a C n-alkylcarboxylic acid and 0.01 to 05.% of an amine selected from the group consisting of alkylamines, cycloalkylamines, morpholine, piperidine and N,N-dimethyl piperazine.

3. The composition as defined in claim 2 wherein the olefinic acid is oleic acid.

4. The composition of claim 3 wherein the amine is morpholine.

5. The composition of claim 3 wherein the amine is dicyclohexylamine.

6. The composition of claim 5 wherein the n-alkylcarboxylic acid is caprylic acid.

7. The composition of claim 5 wherein the n-alkylcarboxylic acid is capric acid.

8. The composition of claim 5 wherein the n-alkylcarboxylic acid is pelargonic acid.

9. The composition of claim 8 wherein the composition contains from 0.01 to 0.05% w. sulfurized oleic acid, from 0.1 to 0.5% W. dicyclohexylamine and from 0.05 to 0.5% W. pelargonic acid.

10. The composition of claim 8 wherein the composition contains 0.02% sulfurized oleic acid, 0.20% w. dicyclohexylamine and 0.10% w. pelargonic acid.

11. The composition of claim 1 wherein the vaporspace inhibitor consists of 0.01 to 1.0% of a sulfurized C unsaturated carboxylic acid and 0.05 to 5.0% of a C n-alkylcarboxylic acid.

12. The composition of claim 11 wherein the unsaturated carboxylic acid is oleic acid.

13. The composition of claim 12 wherein the n-alkylcarboxylic acid is pelargonic acid.

14. The composition of claim 12 wherein the n-alkylcarboxylic acid is caprylic acid.

15. The composition of claim 12 wherein the n-alkylcarboxylic acid is a mixture of pelargonic and heptanoic acids.

16. The composition of claim 12 wherein the n-alkylcarboxylic acid is capric acid.

References Cited UNITED STATES PATENTS 2,257,752 10/1941 Lincoln et al. 252-475 XR 2,268,608 1/ 1942 McNulty et al. 252-475 XR 2,368,605 1/1945 White 252-486 XR 2,829,945 4/1958 Krieg 21-25 3,169,116 2/1965 Baseman et al. 21-2.7 XR

DANIEL E. WYMAN, Primary Examiner.

25 W. H. CANNON, Assistant Examiner.