US2513680A

US2513680A - Lime base grease

Info

Publication number: US2513680A
Application number: US71554A
Authority: US
Inventors: John E Schott; Eldon L Armstrong
Original assignee: Socony Vacuum Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1949-01-18
Filing date: 1949-01-18
Publication date: 1950-07-04
Anticipated expiration: 1967-07-04

Description

Patented July 4, 1950 UNITED STATES PATENT OFFICE LIME BASE GREASE John E. Sch'ott, New Stork, and. Eldon L.Arrnstrong, Garden City, N. Y., assignors to Socony- Vacuum il Gompany, Incorporated, a corpo ration of New York No Drawing. Application January 18, 1949, Serial No. 71,554

tions of the type set forth in Carmichael and Hain, U. '8. Patent 2,197,263.

The-patent above noted is concerned with the provision'of lime base greases stabilized against deterioration at relatively high temperatures by the" incorporation therein of significant amounts, upto about 5% usually, of the calcium salts of m'onobasic fatty acids having not over 6 carbonatoms specifically acetic acid.

The-purpose of the'present invention is to provide-agreaseof this character in which certain properties have been improved. One of the properties thus improvedis that phenomenon known as skin hardening, i. e., a hardening of the surface ofthe grease when exposed to combinations of moderate temperature and high humidity. Another property improved is that demonstrated by'what is hereinreferred to as-the Sett test, wherein the'grease is held for a period of hours at atemperature of 300 F., which conditions havebeen found generally to-bring about perceptible hardening of the presently available greases. A third property improved is that of long time storage stability, it having been noted thatpresentgreases tend to become harder when stored for long periods of time. While these properties of the present greases are not highly objectionable and have not greatly m'ilitated against'wide and ready acceptance of the greases as a premium product, they are nevertheless of a nature that should be eliminated, if possible, in working toward a more perfect product.

This; invention is based upon the discovery that worthwhile improvements in such greases can be effected by the replacement of' a portion of theshort-chain fatty acid modifier by phosphoric acid,- giving rise to a erease'containing a 2 lime soap,.a lime salt of a short chain fatty acid, and, probably; "9, lime salt of an acid of phosphorus.

In general, to arrive at such' modification of the grease, we prefer to use orthophosphoric-acid,

but. wemay use any acidoi phosphorus which, under the conditions of grease manufacture will hydrate or hydrolyze with the production of orthophosphoric acid. Such acids are herein in dicated as phosphoric acid;

An-exemplary composition is the following:

Percent (weight) This formulation was compounded in the conventional compounding procedure, followed by dehydration, driving off moisture while the grease was being stirred. Dehydration is car ried out toia substantial'extent; sufiicient to give the grease the desiredstructure and temperature stability.

While the exact reaction into which the 'phosphoric acid enters hasnot been studied, it is believed that theresult" of the neutralization of the phosphoric acid is formation of a calcium phosphate or" of a calcium compound of a partial ester'ofphosphoric acid. It suffices to say-that the results desiredare'obtaine'd by partial 'substitution of the short-chain fatty acid with phosphoric acid and such language is used for pur- I poses I of definition in the claims.

The improved characteristics obtained-by this formulation may be observed by consideration of the following table of formulae-and test results.

TABLE Lime base, acetate modified grease, further modified with phosphoric acid A B O D E Tallow, Per Cent (by Wt.) 13.45.. 13.45.. 9.85.- 12.50.. 10.1. Oandelilla Wax, Per C 4.00-. 4.00-- 2.93. 3.60-. 2.9. Lime Flour, Per Cent. 5.25.- 5.2 3.84-- 4.70-- 3.8. Glycerine, Per Cent 2.00.- 2.00-- 1.46.- 1.80.. 1.4. Acetic Acid, Per Cent 3.20-- 3.60-. 2.63.- 3.30-- 2.7. Phosphoric Acid, Per C 0.80.. 0.40-- 0.29.- 0.20-- 0.2. Solar Red Oil, Per Cent 71.30-- 71.30-- 79. 73.90-- 78.9. Ritiodoi Phosphoric Acid to Acetic 1:4- 1:9- 1:9- 1:16. 1:13.

01 Analysis:

Alkalinity, OaO, Per Cent.... 0.5 0.45.- 0.3-- 0.34-- 0.3. Saponified Fat, Per C 12.2.- 12.40- 9.9.. 12.80.. 10.4. Unsapom'fled Fat, Per Cent.-- 0.9.. 1.10.. 0.7.. Water, Per Cent Trace. 0.25. 0.2- 0.50. 0.4. Glycerine, Per C 1.2.- 1.10.- 1.0-. 2.80-- 1.2. tls)ropping Point, ASTM, F--- 500+ 500+ 500+ 500+. es

Pelnetrations, ASTM 77 Unwor 486 258 322 Worke 37 22 294 200 303. Sett Test 16 hrs. 300 F. Slightly Hard- Relatively Soit-- No change Slightly Hardened No 'change in conene sis ency. Sett Test 300 F. for 40 do Remained relahours. tively soft. Skin Hardening (Humidity Cab- None in 7 days-- No detectable Slight in 72 inet). gardening 48 hours.

. ours. Storage Stability, Days Stored- 890, No harden- 90 No harden- 84, No harden- 303, Slight hard- 227, No bard- 440, Slight ing. mg. in ening. ening. hardening.

In the above tabulation, the upper portion gives several exemplary formulae, the middle portion gives analyses of the resulting greases, and the bottom portion gives tests of the resulting greases.

In the tests, the Dropping Point ASTM" and Penetrations, ASTM 77 F. are the standard tests as specified by the American Society for Testing Materials.

The Sett Test comprises holding a sample of the grease at the specified temperature for the specified time, and observing the consistency of the grease after such exposure. I

The Skin Hardening test is conducted by coating a panel of small size with the grease, followed by storing in a humidity cabinet at 100 F. and 100% relative humidity for a specified period, after which the grease is observed. The absorption of water vapor by the grease frequently results in the formation of a perceptible skin or crust upon the grease.

Both the above tests are related, as accelerated tests, to the actual performance of the grease in storage, as reported under "Storage Stability which merely reports the condition of the grease after specified periods of storage under conventional conditions.

It will be observed by reference to the table that the above greases underwent no significant change of consistency in the Sett Test, showed no significant skin hardening, and showed no hardening in storage, even under periods ranging up towards two and one-half years.

In contrast to this, a conventional acetatemodified line base grease, compounded in accordance with the formula of column A of the table, excepting that no phosphoric acid was used and the acetic acid Was increased to 4.00 weight per cent will give the following results. It will show perceptible hardening after a sixteenhour Sett Test, it will show perceptible skin hardening after twenty-four hours of exposure in the humidity cabinet, and will, normally, both in laboratory and commercial experience, show a hardening in one year of storage of the order of about acceptance.

30-40 points of penetration, (sometimes 60 points), gm. load, 77 F., ASTM method).

These improvements in properties, while small in amount, are worthwhile in that together they define a grease more nearly free of objectionable features than the parent product, even though that parent product has enjoyed ready and wide In other respects, such as temperature stability under conditions of use, ability to retain oil without separation under normal conditions of use, as well asduring storage, and the like, these improved greases retain the same de-' sirable qualities as exhibited by the parent grease.

While the degree of modification and improvement obtained is of course dependent upon the amount of phosphoric acidused, the improve-Q ments begin to be present in discernible degree with use of about 0.1% by weight of phosphoric acid in the formulation. The optimum amount of phosphoric acid appears to be of the order of from about 0.4 per cent by weight to about 0.7 per cent by weight of phosphoric acid in the formulation. Upon the other hand, amounts of phosphoric acid above about 2.0 per cent by weight appear to be definitely detrimental, and in higher amounts destructive. For example, a grease formulated as in column A of the table, except using acetic acid 0.8 weight per cent and phosphoric acid 3.2 weight per cent was found to be without any grease structure at temperatures of about 240 F. and above, and to carry an insoluble m- This product definitely was not a com-,

of modified lime base greases obtained by the use,

as modifiers, of short-chain monocarboxylic fatty acids of not more than six carbon atoms. The improvements available by substitution, for a portion of this carboxylic acid, of phosphoric acid exist over the range of specified fatty acids.

In general, greases of this type can be achieved,

anew-8o by compounding'together' from --about to about 20 per cent by weight of high molecular weight fia t ae or -a -c n ai ins nf rmi s materials, from about 0.2,to about 5 percent by wei ht of monocarboxylic fatty acids OfJlQlZQi/BI' ccarbon atoms, the preferred, one being acetic acid, from about 0.1 to about 2 weight per cent of phosphoric acid and corresponding amounts of hydrated lime or other reactive form of lime, the hydrated lime ranging from about 0.8 to about '7 weight per cent, the resulting grease being dehydrated sufficiently to give the desired stable structure. In general, the phosphoric acid will be regarded in formulation, as a replacement for the low molecular weight fatty acid, and the organic acid be diminished in amount as the amount of phosphoric acid is increased.

We claim:

1. An improved lime base grease composition characterized by stability at temperatures in excess of 200 C. and by improved storage stability, comprising lubricating oil, lime soaps of fatty acids in grease forming amounts, a small proportion, sufficient to impart said temperature stability, of a calcium salt of a monocarboxylic fatty acid having not more than six carbon atoms, and a small proportion, sufficient to impart said storage stability, of a lime salt of phosphoric acid, phosphoric acid having been present in the formulation of said grease in amounts of at least about 0.1 weight per cent and not exceeding about 2 weight per cent of the grease formula.

2. An improved lime base grease composition characterized by stability at temperatures in excess of 200 C. and by improved storage stability, comprising lubricating oil, lime soaps of fatty acids in grease forming amounts, a small proportion, sufficient to impart said temperature stability, of calcium acetate, and a small proportion, sufficient to impart said storage stability, of a lime salt of phosphoric acid, phosphoric acid having been present in the formulation of said grease in amounts of at least about 0.1 weight per cent and not exceeding about 2 weight per cent of the grease formula.

3. An improved lime base grease composition characterized by stability at temperatures in excess of 200 C. and by improved storage stability, comprising lubricating oil, lime soaps of higher molecular weight fatty acids in grease forming amounts, a small proportion, sufficient to impart said temperature stability and not over about 5 per cent, of a calcium salt of a monocarboxylic fatty acid having not more than 6 carbon atoms, and a small proportion, sufficient to impart said storage stability, of a lime salt of phosphoric acid, phosphoric acid having been present in the formulation of said grease in amounts of at least about 0.1 weight per cent and not exceeding about 2 weight per cent of the grease formula.

4. An improved lime base grease composition characterized by stability at temperatures in excess of 200 C. and by improved storage stability, comprising lubricating oil, lime soaps of higher molecular weight fatty acids in grease forming amounts, a small proportion, suiiicient to impart said temperature stability and not over about 5 per cent, of a calcium salt of acetic acid, and a small proportion sumcient to impart said storage stability, of a lime salt of phosphoric acid, phosphoric acid having been present in the formulation of said grease in amounts of at least about 0.1 weight per cent and not exceeding about 2 weight per cent of the grease formula.

5. Improved lime base greases characterized by stability at temperatures in excess of "200 and by improvedstoragestability formed by :compounding together from about 5 to'about' 20-Jper cent of high molecularaweight fatty acid soap forming'materials, from about 0.2 to about 5 per cent of monobasic fatty acids of not over 6 carbon atoms, from about 0.1 to about 2 per cent of phosphoric acid, from about 0.8 to about 7 per cent of lime, all by weight, the remainder being lubricating oil.

6. Improved lime base greases characterized by stability at temperatures in excess of 200 F. and by improved storage stability formed by compounding together from about 5 to about 20 per cent of high molecular weight fatty acid soap forming materials, from about 0.2 to about 5 per cent of acetic acid, from about 0.1 to about 2 per cent of phosphoric acid, from about 0.8 to about I per cent of lime, all by weight, the remainder being lubricating oil.

7. An improved lime base grease composition characterized by stability at temperatures in excess of 200 F. and by improved storage stability, comprising lubricating oil, lime soaps of fatty acids in grease forming amounts, a small proportion, sufiicient to impart said temperature stability, of a calcium salt of a monocarboxylic fatty acid having not more than six carbon atoms, and a small proportion, sufficient to impart said storage stability, of a lime salt of phosphoric acid, phosphoric acid having been present in the formulation of said grease in amounts of at least about 0.1 weight per cent and not exceeding about 2 weight per cent of the grease formula, the resulting grease being dehydrated to a degree sufficient to give high temperature stability.

8. An improved lime base grease composition characterized by stability at temperatures in excess of 200 F. and by improved storage stability, comprising lubricating oil, lime soaps of higher molecular weight fatty acids in grease forming amounts, a small proportion, sufficient to impart said temperature stability and not over about 5 per cent, of a calcium salt of a calcium salt of acetic acid, and a small proportion, sufficient to impart said storage stability, of a lime salt of phosphoric acid, phosphoric acid having been present in the formulation of said grease in amounts of at least about 0.1 weight per cent and not exceeding about 2 weight per cent of the grease formula, the resulting grease being dehydrated to a degree sufficient to give high temperature stability.

9. Improved lime base greases characterized by stability at temperatures in excess of 200 F. and by improved storage stability formed by compounding together from about 5 to about 20 per cent of high molecular weight fatty acid soap forming materials, from about 0.2 to about 5 per cent of monobasic fatty acids of not over 6 carbon atoms, from about 0.1 to about 2 per cent of phosphoric acid, from about 0.8 to about '7 per cent of lime, all by Weight, the remainder being lubricating oil, the resulting grease being dehydrated to a degree suflicient to give high temperature stability.

10. Improved lime base greases characterized by stability at temperatures in excess of 200 F. and by improved storage stability formed by compounding together from about 5 to about 20 per cent of high molecular Weight fatty acid soap forming materials, from about 0.2 to about 5 per cent of acetic acid, from about 0.1 to about 2 per cent of phosphoric acid, from about 0.8 to about 7 per cent of lime, all by weight, the remainder bemg lubricating oil, the resulting grease being de- REFERENCES CITED The following references are of record in the file'of this patent: 1

UNITED STATES PATENTs Name Date I Carmihfiel r. Apr 16, 1940 Kaufman fi June 17, 1941 Zimmer Oct. 7, 1941 McLennan Mar. 18, 194']

Claims

1. AN IMPROVED LIME BASE GREASE COMPOSITION CHARACTERIZED BY STABILITY AT TEMPERATURES IN EXCESS OF 200*C. AND BY IMPROVED STORAGE STABILITY, COMPRISING LUBRICATING OIL, LIME SOAPS OF FATTY ACIDS IN GREASE FORMING AMOUNTS, A SMALL PROPORTION, SUFFICIENT TO IMPART SAID TEMPERATURE STABILITY, OF A CALCIUM SALT OF A MONACARBOXYLIC FATTY ACID HAVING NOT MORE THAN SIX CARBON ATOMS, AND A SMALL PROPORTION, SUFFICIENT TO IMPART SAID STORAGE STABILITY, OF A LIME SALT OF PHOSPHORIC ACID, PHOSPHORIC ACID HAVING BEEN PRESENT IN THE FORMULATION OF SAID GREASE IN AMOUNTS OF AT LEAST ABOUT 0.1 WEIGHT PER CENT AND NOT EXCEEDING ABOUT 2 WEIGHT PER CENT OF THE GREASE FORMULA.