US2641577A - Lithium-calcium lubricating grease composition - Google Patents

Description

Patented June 9, 1953 LITHIUM-CALCIUM LUBRICATIN G GREASE COMPOSITION Rosemary OHalloran, Roselle Park, N. .L, as-

si'gnor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application June 22, 1951,

Serial No. 233,099

6 Claims. (01. 252-40) This invention relates to lubricating compositions and more particularly to a lubricating composition containing lithium'and calcium salts of a high molecular weight fatty acid.

Briefly stated, this invention comprises a superior high temperature, shear stable, moisture resistant lubricating composition made by thick ening a lubricating oil to a grease consistency with a mixture of the lithium andcalcium soaps of high molecular weight fatty acids inwhich the ratio of the lithium soap to the calcium or strontium soap is within a desired range to be given in more detailhereinafter.

The use of lithium soaps in grease making is known in the art andpatents covering lithium soap grease are numerous. Lithium greases are of value for their combination of water resistance and high dropping point but are sensitive to manufacturing'variables and have relatively poor shear stability. It is also known that calcium soap greases are very desirable for certain purposes, chief among which are for moisture proof lubrication, but have very poor temperature resistance. 7

Although lithium soap greases 1 and calcium soap greases are well known in the art, there is very little known of a grease containing in combination a lithium soap and a calcium or strontium soap, so far as applicant is aware, and nothing at all of a grease containing a combination of the lithium soap and calcium or strontium soap of a high molecular weight fatty acid in which the ratio of lithium soap to calcium or strontium soap is within applicants desired range.

Morway in U. S. Patent 2,355,009 discloses the use of a combination of thelithium and barium soaps of fatty acids'to prepare a grease composition.

Fraser, in U. S. Patent 2,397,956, teaches the manufacture of a grease using a lithium soap of l2-hydroxy stearic acid, or hydrogenated castor oil and discloses that the calcium soap of a higher fatty acid may be combined therewith, preferably as a preformed calcium grease. This combination, however, is directed toward a specific grease composition, one made with a major proportion of the lithium soap oi hydrogenated castor oil.

The instant application difiers in other major respects as will become evident as the description proceeds.

Woods et al., in U. S. Patent 2,470,965, also teaches the manufacture of a grease composition, which contains lithium soap and soluble .calcium soap. Specifically, Woods et al. show the inclusion of a minor percentage of calcium naphthenate asan anti-bleeding agent, that "is, a. substance incorporated into a grease to prevent oil separation during rapid cooling.

In a pending application, Serial No. "100,969

filed June 23, 1949, now Patent No. 2,583,435,

there is discloseda grease combining a lithium salt and acalcium soap. In this disclosura'the fatty acid. When a mixture of the lithium and calcium soaps is used, the mol ratios of the lithium soap to the calcium soap may vary between about 2:1 to 821, the preferred ratio being within the range of 3 mols of the lithium snap to 1 mol of the calcium soap to 6-.mols of the lithium soap to 1 mol of the calcium soap.

When the amount of the lithium soap is increased beyond the 8:1 mol ratio the advantages obtained by the incorporation of the calcium soap decrease markedly, and when-the amount of the calcium soap is increased above. the 3:1 mol ratio, manufacturing difiiculties are encountered, greater amounts of the calcium soap failing to give a grease structure that is stable.

The grease composition of this invention. is an excellent all purpose lubricant, being moisture resistant and very stableto shear breakdown,

having a high dropping point The grease has a-verysmooth texture anda. corresponding excellent appearance. It has several outstanding advantages over other greases of similar composi tion among which may be listed the following:

(1) Increased shear stability of major consideration. in all purpose lubricants.

(2) Manufacture of the greasev composition at lower temperatures- Thegrease of this invention may be manufactured at temperatures as low as320 15'. Other lithium based greases must be made at temperatures as high, insame instances, as 430 F.

(3) Less sensitivity to manufacturing variables. For example, the greases of this invention made from oils having a high viscosity index may be cooled in thick layers or cakes whereas lithium based greases must be-pan cooled or cooled in thin layers. This advantage is obvious.

(4-) A' decreased amount of aeration upon being subjected to mixing-or shear stresses. This is of particular importance when used in high speed bearing suriaces since the incorporation of air intoa lubricantunder-those conditions decreases the lubricating potential. (5) An increased resistanceto the solventac- 3 tion ofhydrocarbons. This permits the use the grease of this invention as a lubricant for surfaces exposed to action of hydrocarbon solvents with improved performance.

Although thegreases of this'invention may be made fromany of the usual natural or synthetic grease-forming fats or fatty acids such as oleic acid, stearic acid, resin acids, beef fat, tallow" or the saturated or unsaturated glycerides of various fatty acids, Fischer-Trop'sch' residues, or mixtures of the above, the preferred embodiment contemplates the use of high molecular weight fatty acids and particularly the high molecular weight substantially saturated acids such as the hydrogenated fish oil acids.

The lubricating oils into which the soaps are incorporated according to this invention may be any of the numerous types of lubricating oils, whether natural or synthetic and may have viscosities of from '60 to 4000 Saybolt seconds at 100 F. Preferably, however, the greases of this invention are made using as a base oil a naturally occurring mineral oil distillate.

Any of the conventionalmethods of manufacture such as cooking in a fire heated kettle followed by drawing into thin pans or deepcakes forcooling, or, due to the lower maximum temperature required to form the greases of this inventional steam heated kettles at a maximum of 325 F. in some cases, followed by coolingwith stirring while runningcold water through the kettle jacket.

The concept of this invention may be more clearly explained by reference to the following examples, which, it is understood, are to be taken as illustrative only.

7 I 7 EXAMPLE 1 The following formulation was used in the preparation of a series of greases according to the instant invention.

vention, they maybe manufactured in the consenting the optimum ratio.

15.00% of hydrogenated fish oil acids having, a saponification value of from 195 to 215 was 'used' with .06- mol equivalents of base consisting of a 'mixture of lithium and calcium hydroxides-the percentages of the base being adjusted to givethe desired molar ratio of lithium soap to calcium soap. The balance of the formulation consisted of the desired base oil and included 0.50% of an cooked for five minutes. After the cooking'a boil- 1 ing water solution of the lithium hydroxidelwas added and the mixed soap mass dehydrated for one-half hour at 200 to 230 F. The masswas then raised to a temperature of about 300 F., during which the remainder of the oil charge'was added in small amount. The temperature Was again raised until the product was completely ,..fluid. At this point, the oxidation inhibitor was added. (At this point, also, other materials such as defoamers can be added.) then poured into cooling equipment and allowed to cool to room temperature.

Various inspection tests were performed on the grease compositions manufactured according; to

The product was more.

the formulation and procedure described above. 5;;

For examination of their structure stability and "shown in Table I beloyvigv j INSPECTION TESTS ON LITHIUM-CALCIUM GREASES Worker Tests, Using Fine 7 Hole Plate, Drop- Penetration (mm/l0) M01 Rm 53ft fiittt F After After 1,000 60,000 Strokes Strokes Thin Layer: 261 337 371 {gialkdf (110 i: run).

in ayer... 346. 359 {gzfikei 333 (1110'; run).

in ayer... 3 34 368 {Cake 3 1 3 343. 2 326. 3 gag 333. 0 347. 346 319 364, 2:1 e 297 fi An examination of the above table will serve to cooling methods in case of the, grease repre- 7 EXAMPLE 2 A specific example. of av grease composition made in accordance with the procedure outlined 'in Example 1 above and containing the optimum ratio of soaps had the; following percentage. composition, all percentages being by weight based on the total composition.

I Per cent Hydrogenated fish oil acids having a sa-' V ponification value of 212 15.00 Lithium hydroxide monohydrate 1.73

Calcium hydroxide (68.0% CaOL 0.82

Phenol extracted coastal distillate having,

a viscosity at 210 Fgof 37 S. U. S 12.40 Phenol extractedPanhandle Distillate hav-v ing a viscosity at 210 F. of 44 S. U. S 69.21

:Phenyl-alpha naphthylamineum- 0.50 Free 7 acidity calculated as oleic acid '(ASTM -D1284'7 method) 0.34

, EXAMPLE 3 r A grease directly suitable for multi-purpose industrial service, v especially where satisfactory lubrication of both automotive and other industrial equipment is required from a single lubricant, may be prepared by applying the concept of this invention to a lithium-calcium grease dis-' 'persed in a coast'al distil-lateof relatively high viscosity, 1'. e. of approximately 500 S. S. at

An example of such grease wasprep-ared according to the following formula using the procedure outlined in Example 1 above: v

p 7 f 1 Per cent Hydrogenated fish oil acids 12.50 Lithium hydro'xidemonohydrate 1.42 Calcium hydroxide 0.67

Acid treated coastal distillate having a viscosity at F. of 500 S. U. S 85.41

In laboratory tests considered significant in the evaluation of industrial and automotive greases, a grease of theab'ove composition shows superior performancein' several respects'to that of a lithium stearate based grease prepared in the same mineral oil. The lithium stearate grease required a manufacturing temperature 75 F. higher than the grease of this invention, a consideration of major economic and safety concern.

Table II MULTI PURPOSE LITHIUM-CALCIUM GREASE Lithium- Shear Stability Properties igg a gf Penetration, IIll'IL/IO.

Unworkcd 60 strokes 60,000 strokes (Fine Hole) Balcrank Dispensing Rate, gJmin. at 77 F1. 51 Micropenetration, mm./l0, Before Micropenetration, min/10, Alter High Temperature Properties:

ing through the Balcrank grease gun under high rates of shear. Somewhat superior resistance to oil separation at elevated temperatures is shown for the lithium-calcium grease (1.4% vs. 2.1 at 210 F.). Oil separation after the Ford wheel bearing test was also observed in the lithium base grease but none in the lithium-calcium grease.

EXAMPLE IV As an illustration of a grease made from a synthetic oil base, a grease having the following composition was prepared:

Per cent Calcium stearate 5.00 Lithium stearate 10.00 Phenyl alpha naphthylamine 0.50 Di-Z-ethylhexyl sebacate 84.50

The dry preformed soaps were admixed with the synthetic ester base and heated to 350 F.,

drawn into pans for cooling and then homogen I ized. The product was smooth in appearance and equivalent in shear stability to a conventional grease prepared from straight lithium stearate.

It is to be understood, of course, that various additives known to the art such as extreme pressure additives, anti-corrosion agents, viscosity index improvers, and the like, may be incorporated into these grease compositions to increase their desirable characteristics.

In summation, this invention comprises a new and superior grease composition having properties that make it outstanding for a general, all

lithium soap to the calcium or strontium soap varies within the range of from 2:1 to 8:1, preferably 3:1 to 6:1.

What is claimed is:

1. A lubricating composition which comprises a lubricating oil thickened to a grease consistency with a mixture of the lithium and calcium soaps of an unsubstituted substantially saturated high molecular weight saponifiable material wherein the molar ratio of the lithium soap to the calcium soap is within a range of from 6 1 to 3:1.

2. A lubricating composition which comprises a lubricating oil thickened to a grease consistency with a mixture of the lithium and calcium soaps of an unsubstituted substantially saturated high molecular weight saponifiable material wherein the molar ratio of the lithium soap to the calcium soap is 4:1.

3. A lubricating composition according to claim 1 in which the high molecular weight saponifiable material is a hydrogenated fish oil acid.

4. A lubricating composition according to claim 2 in which the fatty acid is a hydrogenated fish oil acid.

5. A lubricating composition having the following formulation in which the percentages are by weight based on the total compositions:

Per cent Hydrogenated fish oil acids 12.50 Lithium hydroxide monohydrate 1.42 Calcium hydroxide 0.67

Acid treated coastal distillate having a viscosity at F. of 500- S. U. S 85.41

6. A composition according to claim 1 in which the lubricating base is di-2-ethylhexyl sebacate.

ROSEMARY OHALLORAN.

Moore et a1. Mar. 11, 1952

Claims (1)

1. A LUBRICATING COMPOSITION WHICH COMPRISES A LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH A MIXTURE OF THE LITHIUM AND CALCIUM SOAPS OF AN UNSUBSTITUTED SUBSTANTIALLY SATURATED HIGH MOLECULAR WEIGHT SAPONIFIABLE MATERIAL WHEREIN THE MOLAR RATIO OF THE LITHIUM SOAP TO THE CALCIUM SOAP IS WITHIN A RANGE OF FROM 6:1 TO 3:1.