US 3850825 A
Sulfurization with elemental sulfur of a fatty mixture consisting essentially of about 80-95 weight percent prime burning lard oil and about 5-20 weight percent alkyl oleate yields a sulfur-containing oil-soluble product suitable for use as a substitute for sulfurized sperm oil additives for imparting extreme pressure properties to high aniline point mineral oil lubricants.
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United States Patent Vienna et al.
[ Nov. 26, 1974 SULFURIZED FATTY OILS Inventors: Paul C. Vienna, Calumet City;
Marvin J. Den Herder, Olympia Fields, both of I11.
Assignee: Standard Oil Company, Chicago, Ill.
Filed: Jan. 2, 1973 Appl. No.: 320,076
U.S. Cl. 252/48.6, 260/125 Int. Cl C10m l/38 Field of Search 252/486, 125
References Cited UNITED STATES PATENTS 1 l/l939 Smith 252/486 3,740,333 1/1973 Hutchinson et al 252/48.6
Primary Examiner-W. Cannon Attorney, Agent, or Firm-Edwin C. Lehner; A. G. Gilkes; William T. McClain [5 7] ABSTRACT 5 Claims, N0 Drawings SULFURIZED FATTY OILS BACKGROUND OF THE INVENTION tion agents have been extensively used as metalworking lubricants and especially as cutting oils. In recent years, it has been found that the mineral oil componentof such lubricants contain constituents that may be toxic or carcinogenic in nature and therefore undesirable due to the potential harm that might occur when brought in contact with the human body. It has been found that the polycyclic aromatic constituents natu rally present in most mineral lubricating oils are the undesirable constituents. Accordingly, it is necessary to remove these constituents from the oil in order to have a mineral lubricating oil suitable for the preparation of metalworking oils that are not harmful to the human body. The polycyclic aromatics are highly polar and can be removed by suitable solvent extractionmethods well known to the art. Naturally occurring paraffmic or naphthenic petroleum oils or solvent extracted oils contain less than about 10 percent carbon in aromatic bonding, as determined by the n-d-M Method usedfon determining the hydrocarbon type analysis of lubricating oils, have been found to be relatively free of toxicity and carcinogenicity characteristics. A description of the n-d-M Method may be found on p. 226 of Physical Chemistry of Lubricating Oils by A. Bondi, Reinhold Publishing Corp, N.Y., 1951. Such oils containing minor amounts of the polar aromatic constituents are relatively poor solvents for organic sulfur compounds. Such oils, which are highly refined oils having an aniline point of at least 190F, are now used as the princi pal component of commercial metalworking lubri cants.
Conventional sulfurized liquid triglycerides, such as the naturally occurring fatty oils of animal, vegetable, or mineral origin, are well-known additives for use in the preparation of mineral oil-based metalworking lubricants. Due to the change of the mineral oil used as the base for making compounded metalworking lubricams and the lack of solvency characteristics thereof, it is not possible to form satisfactory oil blends of more than 2-3 percent of sulfurized fatty oils in mineral oil. In other words, the prior art sulfurized fatty oils are substantially insoluble in the aforesaid mineral oilscontaining minor amounts of polar aromatic constituents. The use of the sulfurized fatty oils are desirable for'im; parting additional lubricity to the mineral oil metalworking fluids. V
Another well-known class of sulfurized fatty materials are the sulfurized unsaturated mono-estersof fatty acids as exemplified by methyl oleate.
A widely used sulfurized fatty material is sulfurized sperm oil, for in addition to good solubility, it provides good lubricity, anti-wear properties, and resistance against thermal and oxidative resistance when used as an additive in high aniline point mineral oils. Importation of sperm oil is now prohibited. by the Federal government. Thus, a replacement product is required.
Sulfuri zed lard oil is not a suitable replacement because of its poor solubility in high aniline point mineral oils and also poor thermal and oxidation stability. Methyloleatehas good solubility in high aniline point mineral oils but it has very poor thermal and oxidation stability.
SUMMARY OF THE INVENTION It has been discovered that; a mixture consisting essentially of about to about 95, preferably to 93, w ei ght percent prime burning lard oil and about 5 to about 20,preferably 7 to 15, weight percent alkyl oleate can be sulfurized with elemental sulfur to form a sulfurized product containing from about 8 to about 12, preferably about 9-1 1, weight percent sulfur in the bo'undfform and less than about 0.3 weight percent free sulfur, having the attributes of sulfurized sperm oil. The sulfurized. product. of this invention is a suitable replacement for sulfurized sperm oil for use as extreme pressure additives in high aniline point mineral oils.
1 The term prime burning lard oil as used herein and in the claimsrefers to and means the prime burning lard oil ofcommerce It is highly refined lard oil that has been caustic treated to remove free fatty acids, slimes and proteins normally present in commercial lard oil. It typically contains less than 1 percent free fatty acid, as oleic, has a saponification number of about 197 and an iodine number of about 69.
The tem1*alkyl oleate as used herein and in the claims refers to and means a mixture of alkyl esters of saturatedand unsaturated fatty acids having 14 to 18 carbons, said mixture containing at least 50 weight percent unsaturated fatty acids with not more than 10 weight percent of unsaturated fatty acids containing conjugated double bonds in the unsaturated fatty acid fraction, said alkyl group containing 1 to 3 carbon atoms. A particularly suitable alkyl oleate is the methyl oleate; methyl oleate is obtained. by the alcoholysis treatment of lard oil with methanol which is a wellknown ester interchange reaction. The purified methyl ester mixture typically contains less than 1.5 percent free fatty acids, about 37 percent saturated fatty acids,
and about 58 percent unsaturated fatty acids which includes about 7 percent linoleic acid. In addition, technical grade methyl oleate product typically contains about 7 percent of C1446 saturated fatty acids and about percent of C unsaturated fatty acids which include about 6 percent of linoleic acid, is also suitable for use in this invention.
Sulfurization of the prime burning lard oil and methyl oleate mixture with elemental sulfur is conducted in accordance with conventional sulfurization procedures. Generally this comprises simply heating the mixture with requisite amount of elemental. sulfur at a temperature of about 300400F for about 1-8 hours.
The aniline point (ASTM D-6-l l) measures the solubility"temperature of aniline and the lubricating oil. The aniline point is, therefore, a measure of solvency characteristics of the lubricant. The higher the aniline point, the poorerthe solvency of the lubricating oil.
DESCRIPTION OF PREFERRED EMBODIMENTS A series of sulfurized fatty materials, identified as samples A-H and described below, were prepared.
Each of the materials contained 10 weight percent sulfur. The methyl oleate used in Samples A, C, E, F, and H was the product derived by alcoholysis of lard oil and in Sample D it was the technical grade product, as deof Samples A-C, G and H, were essentially the same. The stick-slip numbers as measured by ASTM D-2877- 70 for these test oils were essentially equivalent.
The compositions of this invention are suitable rescribed above. For purposes of brevity, the prime burn- 5 P e e Q Sulfufiled p rm for use as additives in ing lard oil will hereinafter be referred to as PBLO. lubheahhg 0115 f metal Worklhg P p deslred, Sample A: sulfurized mixture of methyl oleate eh Improvement 9 tempereture sehlblhty can be and p obtained through the incorporation of about 0. l-2 per- Sample sulfurized PBLO. cent of an oil-soluble mono-alkyl phenols, such as non- Sample C; a physical mixture of 10% sulfurized 1O ylphenol n lubricatingoil blends containing the sulfumethyl oleate and 90% sulfurized PBLO' rizgd additi iesfof this lIlVBl'ltlOl'li In h gh pegformanpe Sample D: sulfurized mixture of 10% methyl oleate ushna f as gear gm 6 Way and 90% PBLO mist oils, rock drill oils and multipurpose oils, the properties of lubricatin oil blends containin the sulfurized S g g ample E. sulfurized mixture of 20% methyl oleate and PBLO oil compositions of this invention can be further en- S 0 hanced by the incorporation of small amounts of the ample F. sulfurized mixture of 50% methyl oleate H k 1k ldth. h h l b d d 50% PBLO we nown zinc ia y i iop osp ates u meant a an ditives without any noticeable antagonism in such SampleG: sulfurized sperm oil. blemm sample H: sulfunzed methyl it is to be understood that additive concentrates com- Each of the above sam,ples of s u lfunzed fatty, prising the sulfurized product can be formulated with als was tested for oxidation stability and solubility in a the additives referred to above as we as other addi Fmllme pomt mmeral lubnctmg 01] by dlssolvmg tives, such as silicone defoamer agents and tackiness 5 Welght Percent of l p m solvemextractved agents conventionally used in the lubricating amount. SAE 10 mmeral lubrlcatmg O11 havlhg an ahlhhe P Comparative cutting oils using sulfurized sperm oil and of The OXldahOh test used was e Aecel' the sulfurized products of this invention showed equiverated Breakdown Test No. H-lSO of the American Soalem performance ciety of Lubrication Engineers Standard for Machine Tool Fluid. In this test, 40 grams of test oil and steel We clalm' Copper coupons.are plaqed an Open beaker 1. Asulfurized fatty oil composition consisting essenwhlgh then held wlthout agltatlon for 70 hours at tially of a blend of (a) about 80 weight percent to about 215 F m i P The dllute Color (ASTM D4500) of 95 weight percent prime burning lard oil and (b) about the test oils lS determined before and after the oxida- 5 weight percent to b t 20 ight percent alkyl oletlehfest' Celer of the pp Coupons at the end Ohthe ate sulfurized to contain about 8 weight percent to test 15 determined y T el p V1511 about 12 weight percent bound sulfur and not more examlhed. for deposlts- The e h y was deterthan 0.3 weight percent free sulfur, said alkyl oleate mmed y P g 100 ml of the mlxture In an ASTM being a mixture of alkyl esters of saturated and unsatuinch centrifuge tube and stored at 35F for 48 hou at rated fatty acids having 14 to 18 carbons containing at which time the tube is visually examined for separation. least 50 weight percent unsaturated fatty acids with not The results of the aforesaid tests are set forth in the fol- 40 more than 10 weight percent of unsaturated fatty acids lowing table: containing conjugated double bondsin the unsaturated OXlDATlON TEST SAMPLE M NO. BEFORE AFTER SLUDGE COPPER STEEL SOLUBlLlTY A 2.0 i 3.5 None 3B4A No Deposit Bright & Clear B 2.5 4 None 38 No Deposit Separation C 2.5 6 None 4A-4B No Deposit Separation D 2.5 4 None 3B-4A No Deposit Bright & Clear E 3 6.5 Trace 3B 4A No Deposit Bright 8L Clear F 6 5 8+ Heavy 4B Stain Bright & Clear v' Jh G 2.5 4 None 3B-4A No i gosit Bright & Clear H 3.5 4 Heavy 4-C Stain Bright & Clear These data show that samples A, D and E, of this infatty acid fraction and said alkyl group having 1 to 3 vention are comparable to Sample G, sulfurized sperm carbon atoms.
oil in solubility and thermal and oxidation stability. Sample C, a physical mixture only of the separately sulfurized methyl oleate and PBLO shows such mixture does not have the requisite solubility contra Sample A.
2. The composition of claim 1 wherein (b) is methyl oleate.
3. The composition of claim 2 wherein the amount of bound sulfur is about 9 weight percent to about 11 It is therefore apparent that co-sulfurization of a methyl weight percent.
4. The composition of claim 2 wherein (a) is about 85 weight percent to about 93 weight percent, and (b) is about 7 weight percent to about 15 weight percent.
' 5. The composition of claim 2 wherein (a) is about weight percent, (b) is about 20 weight percent, and
the amount of bound sulfur is about 10 weight percent. i l