US2058236A - Lubricant - Google Patents

Description

Patented Oct. 20,

UN TED-S ES (LUBRICANT Gus kaufman and Oney P. Poi-year, iieacon,

N. Y., assignors to The Texas Company, New .York, N. Y., a corporation of Delaware No Drawing. Application March 21.11934,

' Serial No. 716,648

This invention relates to lubricants and more particularly to greases suitable for use in'ball and roller bearings and the likei Ball and roller bearings of modern machinery require lubricants which are stable and that will withstand the high temperature and rapid agi tation accompanying .ball and roller bearing operation, particularly of high speed equipment. The bearings are often stored for considerable time before use and during this period the lubricant serves as a protective coating; consequently, it is highly desirable that the grease does not deteriorate and form gum which will stick or otherwise damage the bearings. It is advantageous that balland roller bearing greases have melting points sufiiciently high to.prevent the greases from running off the bearings at'operating temperatures, and that the greases remain substantially unchanged in texture 'upon heatmelting points. The greases, furthermore, must not b so hard or spongy that the bearings will :form paths or channels thereinwhereby lubri- Y cation becomes inadequate, nor exert excessive drag on low power, high speed equipment because of too high starting or running torques.

An object of the present invention is to prepare lubricants, which willmeet satisfactorily the foregoing requirements, in a simple and practical manner.. e

In accordance with the present invention, the lubricants are prepared by incorporating, in suitable proportions and under proper conditions, amixed soap 'base of a saturated fatty ingredient with a hydrocarbon lubricating oil. The mixed soap base comprises soda and lime soaps of stearic acid while the hydrocarbon lubricating oil is, preferably a relativeLy low viscosity paraffinic oil of about 200 seconds, Saybolt universal, at 100 F., although other lubricating oils may be used.

In preparing lubricating compounds in accordance with the present invention the stearic acid, in mixture with suitable amounts of water and I 45.1ubfricating oil, is partially saponifiedwith soda at temperatures sufficiently high to effect rapid saponification when alkali is added, but preferably below the boiling pointof water. The lime is then added and finally/more soda, if necessary, to bring about complete saponification. The mixture is heatedto dehydrate the grease, mineral oil is then added, and the grease is stirred until a uniform texture is obtained. The ratio of lime to soda soap in the final product is preferably around 1:5 although this may range being and agitation even at temperatures near the 1 tween the limits of 1:4 and 1:6 with good resill 'AThe general method used-in practice for preparing greases of the present invention is to charge thestearic acid to an ordinary steam jacketed grease kettle and suficient mineral oil andwater added to aid in saponification and to prevent lumpiness. Usually about 10-20% of water and 50-75%v of mineral oil are suflicient. The mixture is then heated until thestearic acid melts and the caustic soda gradually added over a period of about an hour. It is oftennecessary to raise the temperature further in order to prevent solidification as ,the saponification pro- .ceeds. The lime in the form of a suspension in about twice its weight of water is now mixed into the mass and. the tejmperature increased,

- to about '175-185'F. After stirring for about 1 to 2 hours, the temperature is further raised to around 220 F.

The mass at this point usually puffs up as water boils OE and -we have found that it is desirable to add small portions of the oil to aid the dehydration. The mixture finally assumes a tdugh, semi-fibrous texture and it is then stirred an additional A to hour to insure uniformity, but care is taken that the temperature does not exceed 240-250 F. for any 'apvpreciable time since the color will be impaired.

The heat is now shut off. and mineral oilis added slowly at first and therate gradually increased until the necessary amount is added. The grease is drawn from the kettle at about 180- l90 F.

For purposes of' further illustrating the invention an example will now be given of a grease prepared in accordance with the invention, although the invention is not limited to the specific example.

- Percent Stearic acid l 18.21 Caustic soda (49% solution) 4.85 Hydrated lime 0.46 Water e 3.04 Pale oil (200 seconds Saybolt universal at The stearic acid (300 lbs. was broken into small pieces and charged -a grease kettle.

Water (50 lbs.) and 200 pale mineral oil (225 lbs.) were then added. The mixture was agitated and sufficient, heat applied to raise the temperature, to =-135 F. at which temperature the stearic acid melted. The caustic soda (80 lbs. of 49% solution) was then run in over a period of about one hour, and after about three-fourthsof it had been'added the. heat was slightly increased.

utes. -The temperature of the mass was increased to 180 F. and held at that temperature,

with stirring, for about two hours. At 170 F. the mass became dough-dike and at 180 F. or above it softened and settled to the bottom'of the kettle. The temperature was raised to 220 F. and the product increased 2-3 times in volume as the water vaporized, and small dosages of oil were added at intervals.

After dehydration, the mixture "assumed a tough, semi-fibrous texture. oil to make a total of 1210 lbs. was then added over a period of about four hours while stirring was continued and the temperature maintained at l80-l85 F. The oil was added gradually at first and then faster as more oil was incorporated. By careful regulation of the temperature, stirring and addition of oil, 'atexture may be obtained which is characteristic of the product just before it changes from a fibrous to a buttery condition. The product obtained tested as follows:

Calcium soap 3.9% Sodium soap 16.0% Mineral oil 78.7% Free alkali 0.3% Water None Melting point 352 F. Penetration (A. S. T. M., unworked) 260 The consistency of the grease may be controlled by varying the quantity of mineral oil used. Also, heavier or somewhat lighter oils than 200 viscosity stock may be employed and the viscosity of the lubricating oil ingredient will obviously have some efiect on the consistency of the grease. We have used oils varying in viscosity from 180 to 300 Saybolt universal viscosity at 100 F. with success,

and even heavier oils, say 500 viscosity and above,

are contemplated.

The percentage of mineral oils also may be varied within quite broad limits. pared commercial grades of greases varying in hardness from to over 375 A. S. T. M. penetration by varying the mineral oil between the limits of about 65-82% by weight of the finished grease. It is believed that percentages of mineral 011 between and 85% may be used with SUCCESS.

Sumcient mineral We have pre- The lubricants prepared in accordance with the invention have a characteristic texture consisting of short fibers and it is believed that this peculiar fibrous texture gives desirable properties, such as low starting and running torques, freedom from channeling, and ability to maintain a film of lubrication with minimum change in texture over wide ranges of temperature.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

l. A lubricating grease for high speed ball and roller bearings consisting essentially of a mixed soda-lime soap of stearic acid, in which the ratio of lime soap to soda soap is around 1 to 5, and

about -85% of light lubricating oil, said grease being substantially anhydrous and free from glycerine and characterized by having a short fibre texture.

2. A lubricating grease forhigh speed ball and roller bearings consisting essentially of about 20% of a mixed soda-lime soap'of stearic acid, in which the ratio of lime to soda soap is about 1 to 5.25, and in the region of of mineral oil of to 300 Saybolt viscosity at 100 F., said grease being characterized by having a short fibre texture and being substantially free from water and glycerine.

3. A lubricating grease for high speed ball and roller bearings having substantially the following