US2197263A - Grease composition - Google Patents

Description

P tented Apr-: 1940. Y

. TED STATES: PTATENT OFFICE.

oaaasn comosrriou Emmett S. Carmichael, Jackson Heights, N. Y., and George M. Hain, Montclair, N. J., asslgnors to Socony-Vacuum Oil Company, Incorporated,

New York, N. Y., a corporation of New York No Drawing.

Application February 23, 1939,

Serial No. 257,958

13 Claims.

This invention is directed to improvements in lime base greases, that is to grease compositions consisting basically of mineral oils in admixture with lime soaps or with a suflicient pro- 5 portion of lime soap to have the characteristics usually attributed to lime base greases. Such greases in their usual form constitute the usual commercial cup greases and are useful for unexacting services at low temperatures. Lime base greases of the normal type are not capable of use at elevated temperatures since they lose stability at temperatures in excess of about 175 F. and are entirely unstable at temperatures near or above the normal boiling point of water 5 due to excessive loss of moisture and consequent disintegration of the grease.

This invention has for its object the provision of novel and improved lime base greases characterized by stability at temperatures well no above those at which normal 'type lime base greases are applicable.

This invention is based upon the discovery that by compounding in thelime base grease small controlled amounts of certain ingredients heretofore novel in lime base greases, greases are obtained which, while possessed of the usual desirable characteristics of lime base greases are additionally possessed of stability at temperatures far in excess of the upper temperature limits at which normal types of lime base greases are capable of being applied.

This invention is further based upon the discovery that when lime base greases containing such ingredients are dehydrated in manufacture still further gains in ability to resist high temperature are effected.

This invention is based upon the discovery that by the addition to lime base greases and to those mixed lime-soda base greases in which lime soaps predominate and which substantially retain the characteristics of lime base greases, of a small amount of the calcium salts of low molec- 5 ular weight organic acids either alone or in combination with controlled small amounts of mentan wax, there results a grease having temperature stability greatly enhanced over that of the usual lime base greases.

As an example of a typical formula for the improved grease, the following formula is given in which per cents are by weight:

Exmrml I -Per cent Hydrofol fatty acids... 5.5 Cottonseed fatty acids 5.5 Refined montan wax 2.0

Low molecular weight organic acids having the general formula cnHznoil, where n is This grease, compounded according to the above formula is contrasted with a conventional lime base grease formula, which is as follows:

Conventional lime base grease formula Per cent Tallow 16.0 Lime flour 2.4 S. U. V. 100 F. mineral oil 81.6

"In the above formula the 100" paraffin oil is a lightmineral oil having 100" Saybolt viscosity at 100 F. It will be understood that in accordance with practise, other oils may be substituted for this oil, dependent upon the nature of the lime-base grease desired. Lime flour is the usual product of commerce. and tallow, where mentioned, are usual products of commerce. Hydrofol fatty acids are fatty acids derived from hydrogenated fish oils appearing in the trade under several names, one of which is Hydrofol. Montan wax is the ordinary crude or refined montan wax of com- Cottonseed fatty acids 7 merce, except for greases of the cold sett type illustrated by Example I, where refined montan wax should be used.

The greases in Examples I and II, exhibited very marked degrees of improvement in heat stability over the conventional lime base grease. For example, two tests are used to show these properties.

The first test is a proposed method of test for dropping point of lubricating greases, described on pages 14 and 15 of the September, 1937 issue of the A. S. T. M. Standards of Petroleum Products and Lubricants, Prepared by Committee D-2. This dropping point test consists essentially of placing the grease within a grease cup which has an open orifice of specified diameter at the bottom and is surrounded by a heating jacket. Upon raising the temperature gradually, the temperature is observed at which the first drop of grease passes through the orifice.

This test gives information as to when the grease is softened, by heating, to a point of leakage and dropping through an orifice of specified diameter. Although the test is made on a grease sample in a perfectly quiescent state and, therefore, may not represent the actual service conditions, it gives valuable indication as to the consistency which may be expected in grease feeding devices at elevated temperatures and which, in turn, has a bearing on the consumption of the grease.

The second test is conducted in the socalled B. E. C. grease testing machine, developed by the Bearing Engineers Committee of the Anti-Friction Bearing Manufacturers Association. This machine has been developed to study the structural stability of greases when agitated in a working ball bearing under specified conditions at known temperatures. Essentially, it is a ball bearing assembly operated at 3450 R. P. M. by a vertical motor and suspended in an oil bath, the temperature of which can be conveniently maintained at any level up to 300 F. The inner race of the bearing is mounted on the extension spindle of the motor, and the outer race can be rigidly set in a grease cup. This cup is free to turn with the bearing to allow torque measurements. A known amount of grease is packed into the bearing and around the shaft. The bearing is shielded by a plate on the bottom side with a small circular clearance between the shield and the outer race. Any leakage of oil or molten grease through this clearance is collected on the bottom of the grease cup and can be quantitatively determined. The initial test is conducted at Bil- F., and subsequent tests are made at F., 180 F., and 220 F. as required, the duration of each being 20 minutes. During all of these tests, separation of oil, change of structure, channelling, and aeration are noted, in addition to the torque readings. The B. E. C. tester is valuable for predicting the suitability of greases for ball bearing lubrication at elevated temperatures.

Exemplary of the increased stability of greases made in accordance with this disclosure are the following results:

1. Using a grease compounded according-to Example I, in the proposed A. S. T. M. drop point determination, this grease was found to drop at approximately 285 F., whereas a conventional lime base grease of about the same consistency, drops at approximately 212 F.

2. Using the B. E. C. machine, the grease of Example I was compared with a conventional lime base grease, with the following results:

Experimental Conventional lime base grease (Example 1 (#4 cup grade) Temp Time of aga Temp Time of #3: F. test me F. test hum Minutes Minnie: 80 20 None.... 80 20 None.

150 20 do-- Z) Do.

20 Trace- 180 20 10.

220 20 6 220 20 Cup was full.

Approximately 30%. The machine is not designed to measure higher leakages.

A grease prepared in accordance with the above formulation shows a total leakage of approximately 8% when tested in the B. E. C.

machine for 3 hours at 180 F. and 1 hour at 220 F. A conventional lime base grease of approximately the same consistency (#4 cup grade) will become semi-fluid and the sample will flow thru and out of the bearing under these conditions.

Additional comparative tests in the B. E. 0. machine, between the conventional grease set forth above in this specification and the grease for Example II are as follows:

Percent total leakage Temp., F. Duration Conventional Example II None None. Full cup. Do

'30 plus. The machine is not designed to measure higher leakages.

It will be noted that the conventional grease which showed excessive leakage from the bearing after 20 minutes 150 F., was improved by the addition of calcium acetate. to the point of satisfactory service 180 F.

A highly stable form of lime base grease results from a modified treatment of a grease containing the same novel ingredients. By such modifications, a similar lime base grease may be prepared which does not change its structure or consistency at elevated temperatures in the neighborhood of 300 F., even after prolonged use.

An exemplary formula for such a high temperature lime base grease is given below:

ExmLs III Per cent Hydrogenated fatty acids 5.5 Cottonseed fatty acids 5.5 Refined or crude montan wax 4.0 Low molecular weight organic acids having the general formula CnHZnOB, where n is preferably 6 or less, e. g., acetic acid 4.0 Lime flour; 4.6

100 Sec. paraflln oil 76.4

- portions of ingredients, other Experimental grease (Example III) Time of Total leakage, test percent Minute:

Total leakage,

Time of Temp., F. t percent est Minutes 20 Cup was full.

Approximately 30%. .The machine is not designed to measure higher leakages.

It will be noted that the greases according to the improved formula contain montan wax. This montan wax is of significance in two respects. In the first place, in the presence of montan wax, all of the complements can be combined into the finished product in one operation, whereas attempts to incorporate the calcium acetate without montan wax have been found to require a twostep operation in which calcium acetate is incorporated into an already prepared lime base grease. In the second place, the combined use of montan wax and low molecular weight organic acids results in improvements not attainable with either of these components alone.

That enhanced properties arise from the presence of calcium acetate which are not secured by the addition of montan wax alone is evident.

which is seen to be essentially the same as the conventional grease except for the addition of montan wax, when tested in the B. E. 0. machine, was found to have leakage characteristics the same 'as the conventional formula. Some improved characteristics do follow, however, from the addition of montan wax which unquestionably assists in the stability of the entire combination.

Another outstanding feature of some forms of this product, as illustrated byExample I, is their ease of manufacture. This form can be prepared at temperatures below F. by simply mixing the lime "s1urry with the oil-acid mixture and stirring until homogeneous. It, therefore, offers possibilities for continuous grease manufacture.

It will, of course, be realized that various proportions of the various ingredients may be used for the compounding of greases of varying characteristics within the field defined by this disclosure. In such varied compositions the prothan the oil to be used, are as follows:

1. Less than 30% of fatty acids, glycerides or mixtures thereof, the preferred range being from of such constituents.

2.'Less than 10% of calcium acetate or its equivalent, the minimum amount being approximately 0.2% and the preferred amounts being from 0.5% to 5.0%.

3. Less than 7% of montan wax, the preferred amount being one to five percent.

We claim:

1. An improved lime base grease composition characterized by stability at temperatures inexcess of 200 F. comprising lubricatingoiland lime soaps of fatty acids and in addition thereto a small proportion of the calcium salt of a monobasic fatty acid having not more than 6 carbon atoms.

2. An improved lime base grease composition characterized by stability at temperatures inexcess of 200 F. comprising lubricating oil and lime soaps of fatty acids and in addition thereto a small proportion of calcium acetate.

3. An improved lime base grease composition characterized by stability at temperatures in excess of 200 F. comprising lubricating oil and lime soaps of fatty acids and in addition thereto small proportions of calcium soaps of montan wax acids and of monobasic fatty acids having not more than 6 carbon atoms.

4. An improved lime base grease composition characterized by stability at temperatures in excess-of 200 F. comprising lubricating oil and lime soaps of fatty acids and in addition thereto small proportions of calcium'salts of acetic acid v and of montan wax acids.

5. An improved lime base grease composition characterized by stability at temperatures in excess of 200 F. comprising lubricating oil and lime soaps of high molecular weight fatty acids and'a small proportion, not over about 5%, of the calcium salt of a monobasic fatty acid havin not over 6 carbon atoms.

6. An improved lime base grease composition characterized by stability at temperatures in excess of 200 F. comprising lubricating oil and lime soaps of high molecular weight fatty acids and a small proportion, not over about 5%, of the calcium salt of acetic acid.

7. An improved lime base grease composition characterized by stability at temperatures in excess of 200 F. comprising lubricating oil and lime soaps of high molecular weight fatty acids to which have been added not over about 5% of calcium acetate and not over about 7% of montan wax.

8. Improved lime base greases characterized bystability at temperatures in excess of 200 F. formed by compounding together from 5 to 20% of high molecular weight fatty acid soap forming materials, from 0.2 to 5% of monobasic fatty acids of not, over. 6 carbon atoms, from 1 to 7% of montan wax, from 0.95 to 6.5% oflime flour, a

the remainder being lubricating oil.

'9. An improved lime base grease composition characterized by stability at temperatures in excess of 200 produced by compounding together- 10. An improved lime base, grease composition characterized by stability at temperatures its in excess of 200 F. produced by compounding together- Per cent Hydrogenated fatty acids 5.5 Cottonseed fatty acids 5.5 Refined montan wax 2.0

Low molecular weight organic acids having the general formula CnHznOz, where n is preferably 6 or less, e. g., acetic acid 2.0 Lime flour 3.4 100" parafiln oil 81.6

, suificient to give high temperature stability.

aromas 12. An improved lime base grease composition characterized by stability at temperatures of approximately 300 F. comprising lubricating oil and lime soaps of fatty acids and in addition thereto small proportions of calcium soaps of montan wax acids and of monobasic fatty acids having not more than 6 carbon atoms, the grease being dehydrated to a degree suflicient to give high temperature stability.

13. An improved lime base grease composition characterized by stability at temperatures of approximately 300" F. comprising lubricating oil and lime soaps of fatty acids and in addition thereto small proportions of calcium salts of acetic acid and of montan wax acids, the grease being dehydrated to a degree sufflcient to give high temperature stability.

EMME'I'I S. CARMICHAEL. GEORGE M. HAIN.