US2246467A - Lubricant - Google Patents

Description

Patented June 17, 1941 LUBRICANT I Gus Kaufman and Robert S. Barnett, Beacon, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application March 14, 1939, Serial No. 261,772

18 Claims.

This invention relates to lubricants and more particularly to lime soap greases and liquid lubricants.

This is a continuation-in-part of our copending application, Serial No. 193,851, filed March 4, 1938.

Ordinary lime soap cup greases as usually manufactured are composed of mineral lubricating oil, lime soap prepared-from fats, such as tallow or tallow oil, a portion of the glycerine liberated in the saponification of the fat and remaining unvolatilized, and a. small amount of Kvater to stabilize the product against soap separation. In the manufacture of these greases, it is difflcult to adjust the .water content required for stabilization. The final products have poor heat stability, relatively low melting points of the order of 200 F. and below, and break down into soap lumps and oil when heated to temperatures at or above their melting points. Such greases are unsuited foruse in bearings which operate at elevated temperatures, due to the fact that the greases break-down in the bearings at about 150-175 These ordinary cup greases also. have poor storage stability, are susceptible to oxidation, become rancid, develop red to brownish colors on the surface, and cause corrosion, pitting and even seizure of bearings packed therewith. In view of these limitations, the field of use of such cup greases has been limited primarily to cups on shafting and the like where elevated temperatures much above 175 F. are not encountered, and where the grease is put in the cup and used up rather rapidly, requiring frequent replenishment.

It is an object of the present invention to provide a premium grade lime soap grease having a wider field of use than ordinary cup grease, which has a substantially higher melting point of the order of 220 F. and above, which is heat stable and does not break down at temperatures even above its meltlng'point up to 300 F. and above, and wh ch has improved storage stability against oxidation, texture changes and sweating of oil.

A further object of the invention is to provide an improved lime soap grease of this character wh ch is anhydrous, substantially free from glycerine, prepared from fatty acids of the character adapted to impart higher melting points and other improved characteristics to the product, and stabilized with high boiling non-volatile organic stabilizers of such character or in such proportions and combinations as to impart superior storage and heat stability and other advantages as more fully pointed out. hereinbelow.

In the manufacture of the lubricant or grease of this invention fatty acids are-employed rather k than fats or fatty oils, in order to avoid the Saiponification number 197 Neutralization number 193 Iodine number l Titer C 54.6

liberation of glycerine which would be mainly non-volatile and retained in the product at the temperature of manufacture. We have found that it is important to have the grease substangrease or lubricant 'may be prepared from the customary fatty acids, such as stearic, palmitic,

tallow fatty acids, etc., and a fairly good product obtained by the combination of stabilizers employed in accordance with our invention, we have found that a superior product of this character having a higher melting point, increased heat stability and better texture, consistency and resistance to oxidation is obtained by the use of saturated fatty acids of higher molecular weight. These fatty acids may be split from hydrogenated oils or fats, particularly hydrogenated marine or fish oil. Preferably the fatty acids should contain in excess of 40% of saturated acids higher in molecular weight than stearic acid. As an example, commercially available fatty acids, known as Snodotte acids having the following stated composition have been found to be eminently suitable:

Typical tests on a commercially available Snodotte acid are as follows:

Another suitable commercially available product is that known as Hydrofol, acids, which are also saturated fatty acids split from hydrogenated fats of this character.

In the manufacture of the greases or liquid lubricants of the present invention, the proportions of the soap may vary within quite wide limits, depending upon the grade or consistency of the grease desired. The soap, for example, may range from about 1% to 30% or more, giving products varying from liquid to solid greases. The amount of lime employed in saponifying the fatty-acids should be substantially the grammolecular equivalent amount, providing a grease which is generally veryslightly on the acid side in the presence of the stabilizers employed. In-

suflicient lime leaving a substantial proportion of free fatty acids of the order of about 1% or more roduces an abnormal waxy r rough product,

depending upon the drawing temperature, and which has a melting point about 20 F. lower than would otherwise be obtained'with the equivalent amount of lime. The use of an excess amount of lime of the order of 0.5% and over on the basis of the finished grease produces a granular product having little grease structure which is sub ject to heavy oil separation and is entirely unsuitable.

In the manufacture of the grease of our invention, all water added with the lime and other materials is driven off to produce an anhydrous or dehydrated grease. In order to stabilize the resulting product, we employ a controlled small proportion of a specially selected high boiling non-volatile organic stabilizer, and preferably a mixture of such stabilizers of diiferent properties and character, these stabilizers being oil miscible. While various organic stabilizing solvents have heretofore been proposed, none have been found to give the superior products of the present invention which are attained by the combination ofthe particular stabilizer, or combination of stabilizers, employed in the proportion ranges set forth, with the particular fatty acids used. We have found anhydrous lanolin to be a superior stabilizer of this character. By the term lanolin, it is to be understood that we contemplate the various purified and semi-purified greasy materials obtained from the washing of wool, including neutral degras or wool fat, and the commercially purified product sold under the name of lanolin. The latter is preferred for Purposes of our invention. As examples of suitable types of lanolin that are commercially available, we mention such products as Rowag No. 2, A anhydrous lanolin and anhydrous lanolin U. S. P. Typical tests on A" anhydrous lanolin are the following:

Neutralization number 1.48 Iodine number 45 Free fatty acid (A. S. T. M. method 3) percent 0.74 Water 210.... None Another superior type of stabilizer for purposes of our invention is found in certain selected higher fatty acid esters of polyhydric alcohols, such as glyceryl monostearate, triethylene glycol distearate and triethylene glycol monostearate. From the standpoint of effectiveness, availability and cost, the glyceryl monostearate is preferred. Typical tests on a commercially available glyceryl monostearate are the following:

H value (sealed tube method) 325-327 Free fatty acid ..percent 1.56

While it has heretofore been proposed to employ glyceryl monostearate in a proportion of 2-8% as a stabilizer for a lime soap grease prepared with the use of a Mid-Continent distillate lubricating oil of the mixed base or paraflln base type, we have found that unusually superior results in the manufacture of a. premium grade cup grease oi the anhydrous and glycerine-free type are obtained by the use of a naphthene base oil in combination with an effective proportion range of glyceryl monostearate of 0.1 to 0.7%. While somewhat higher percentages of, the stabilizer effect stabilization of the product against oil separation in storage, the greases so prepared are subject to very serious objections due to false consistency, and crust formation upon standing, which render them unsatisfactory from the commercial standpoint. We have therefore found that the lower proportion range of glyceryl monostearate is critical in the preparation of the superior type of lubricant or grease-from a naphthene base oil.

We have further found that in the case of certain types of liquid lubricants or greases of this character prepared from naphthene base oils, lanolin is eflective as a stabilizer in the proportion range of 0.5-3.0%. However, unusually good results are obtained by a combination of 0.1- 0.7% glyceryl monostearate with about 0.4--2% lanolin, giving greater stability against oil separation on storage and greater freedom from setting-up or hardening and crust formation upon standing than is obtained with any other stabi-, lizer or combination of stabilizers known. In the higher soap content greases ranging from about 10 to 30% lime soap of Snodotte acids and which are semi-solid to solid in consistency, we prefer to employ about 02-05% glyceryl monostearate together 'with about 1.0% lanolin. In the lower soap content greases which are liquid lubricants containing from about 6% to 1% or less of lime soap of Snodotte acids, we generally prefer to maintain the lanolin content approximately constant at about 1%, and decrease the glyceryl monostearate content in accordance with the lowering of soap'content to about 0.1-0.2%. In

the case of certain liquid lubricants adapted for use as slushing oils, and containing generally in the neighborhood of 1-6% lime soap of Snodotte acids, lanolin is particularly useful to secure the required stabilizationwhile obtaining the added benefit of the rustproofing properties of 'the lanolin. However, further improvement and a superior product may be secured in this case by employing a very small amount of glyceryl monostearate in combination with the lanolin in the proportion ranges set out above.

The lubricating oil preferred in the manufacture of the premium grade cup greases and the liquid lubricants of the character of slushing oil is a naphthene base oil. A typical naphthene base oil for this purpose is represented by one having the following tests:

This is a typical so-called 300 pale oil which is highly satisfactory for the various grades of cup greases and for liquid lubricants, although it is obvious that heavier or lighter lubricating oils or blends thereof may be employed.

In the manufacture of greases or liquid lubricants of this type, the fatty acids and a portion of the mineral lubricating oil are charged to the kettle and heated with stirring to melt the acids, such as to a temperature of about -160 F. The lime in a slurry' with a small amount of water is then added slowly with continued heating and agitation to effect saponification of thethe lubricating oil is then added slowly in stepwise portions while the mass is stir'red and allowed to cool slowly to below 200 1'. preferably to about 175 E, the final quantities of voil being introduced at about this lower temperature to obtain'the best consistency and buttery texture. In the cooling of these greases, there app ars to be a critical stage between about 240 and 200 F. whilethe mass is being stirred,'during which a granulation or the formation of lumps in the product may occur, provided the proportions of stabilizers are not held within the critical ranges set forth above, but when such ranges. are maintained, a final desirable buttery texture is developed at 200 F. and below. The presence of the lanolin greatly assists in avoiding "this Lime-high test (available Ca (OH) 2 93.6% v 1. 10 Glyceryl monostearate mixture (1:1 in 300 pale oil)- 0.58 Lanolin 0. 58

The full quantity of'Snodotte acids and twenty, pounds of the 300 pale oil were charged to the.

kettle and heated with stirring to melt the acids.

When the mass reached 135 F. and the acidswere all melted, the addition of the lime suspension was started, the lime being added over a period of approximately 15 minutes with theteme perature rising slowly to about 142 F. The heat was then increased whilestirring was continued so that the temperature of the-mass rose overa period of several hours to about 250 F. The glyceryl monostearate mixture was then added,

followed by the addition of lanolin and the term.

perature was further raised to about 260 F. with stirring. The balance of the oil was then added in stepwise portions over a period of approximately four hours while the temperature dropped slowly to approximately 175 F. A fairlyfirm pale grease of buttery adhesive texture and good body was obtained upon drawing andv cooling-in containers in normal manner- This represented a typical premium grade cup grease of medium heavy consistency having the following tests and composition:

Calcium soap percent 14.8 Glyceryl monostearate do 0.5 Lanolin do;' 1.0 Lubricating oil-300 S. U. viscosity at 100 F percent 83.7

Free fatty acid (as oleic) A. S. T. M.

' percent 0.11 Penetration A. S. T. M., unworked 198 Penetration A. S. T. M., worked 325 Melting point, modified dropping pointmethod F 237 The following example is illustrative of the effect of adding a higher percentage of lime soap of Snodotte acids to produce a No. ii grade grease,

which is somewhat softer or less viscous than would ordinarily be obtained by that percentage of soap. This practice is found to give an excellent product which displays decreased working down tendency in service, and a higher melting point.

Example 2-Formula Pounds Snodotte acids 12 300 pale oil 51.4

Lime-high test (available Ca (0H) 2 93.6%) 1. 73

Water (with lime) 6 0 Glyceryl monostearate mixture (1:1 in 300 pale oil) 0.51 Lanolin 0.65

The full quantity of Snodotte acids and 20 pounds of the 300 pale oil were charged to the kettle and heated with stirring to melt the acids. when the mass reached 160 F., the addition of the lime slurry was started, the lime being all added overa period of approximately fifteen minutes and with the temperature rising slowly to about 185 F. The heat was then increased while stirring was continued so that the mass rose over a period of several hours to about 260 F. to effect dehydration. All of the lanolin-was then added, and after about 15 minutes further agitation with the temperature at about 240-260 F.,. the mixture of glyceryl monostearate in pale oil was added. The balance of the oil was then introduced in stepwise portions over a period of about five hours while the temperature dropped slowly to about 200 F. Stirring was continued another hour while the temperature dropped to about 175 F., and a smooth buttery texture of the grease obtained, when the grease was then drawn and cooled. A hard medium consistency smooth grease of light amber color and buttery and adhesive texture possessing good body was obtained, having, the following tests:

Calcium soap percent 20. 0 Glyceryl monostearate do 0. 4 lanolin do 1. 0 Lubricating oil.300 S. U. viscosity at F percent '78. 5 Free fatty acid (as oleic) A. S. T; M.

-percent 0. 28 Penetration A. S. T. M., unworked 205 Penetration A. S. T. M., worked 277 Melting point, modified dropping point method F 243 The dropping point method for determining melting point of greases as conventionally used inresistant as to string out and even touch the bottom of the test tube in which the melting point is taken without a drop detaching itself completely. The modified dropping point method" for determining melting pont referred to above means that temperature at which the grease begins to string out from the mass, though no detached drop may be formed.

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 apended claims.

We claim: 1. A substantially completely dehydrated lime 3. A substantially completely dehydrated lime soap lubricant free from glycerine comprising mineral lubricating oil, calcium fatty acid soap, and about 0.5-3.7% of an added stabilizer mixture of a substantially neutral lanolin and a higher fatty acid ester of a polyhydric alcohol other than a triglyceride, both the lanolin and the ester being present in substantial amounts to stablize the lubricant against soap separation on storage by their conjoint action. with the ester present in an amount below that which produces setting up and crust formation of the lubricant on storage.

4. A lubricant as defined in claim 3, in which the higher fatty acid ester of a polyhydric alcohol is glyceryl monostearate.

5. A lubricant as defined in claim 3 in which the calcium fatty acid soap' is lime soap of a mixture of saturated fatty acids from hydrogenated fatty oil, said mixture of fatty acids containing an excess of 40% by weight of saturated fatty acids higher in molecular weight than stearic acid.

6. A substantially completely dehydrated lime soap lubricant free from glycerine comprising mineral lubricating oil, calcium fatty acid soap,

about (Ll-0.7% glyceryl monostearate and about 0.4-3.0% substantially neutral lanolin.

7. A substantially completely dehydrated lime soap lubricant free from glycerine comprising naphthene base mineral lubricating oil, lime soap or a mixture of saturated fatty acids from hydrogenated fatty oil, about 0.1-0.7% glyceryl monostearate and about (DA-3.0% substantially neutral lanolin.

8. A substantially completely dehydrated lime soap grease free from glycerine comprising about 10-30% lime soap of a mixture of saturated fatty acids from hydrogenated fatty oil, about 0.2-0.7% glyceryl monostear'ate, about 0.4-3.0% substantially neutral lanolin, and the balance a naphthene base distillate lubricating oil.

9. A substantially completely dehydrated lime soap liquid lubricant free from glycerine adapted ,j;

for use as a slushing oil comprisinga mineral lubricating oil, about 1-6% of lime soap of a mixture of saturated fatty acids from hydrogenated fatty oil, as the entire soap content, and about (LS-3% of added substantially neutral lanolin as a stabilizer.

10. A substantially completely dehydrated lime soap liquid lubricant free from glycerine adapted for use as a slushing oil comprising a mineral lubricating oil, about 1-6% of lime soap of a mixture of saturated fatty acids from hydrogenated fatty oil, and a small amount of an added mixture of glyceryl monostearate and sub; stantially neutrallanolin as a stabilizer providing about 0.1-0.5% glycerol monostearate and about 0.42.0% of substantially neutral lanolin.

11. The method in the manufacture of a substantially completely dehydrated lime soap lubricant free from glycerine which comprises heat ing and mixing together saturated higher fatty acids free from glycerides and mineral lubricating oil, adding a slurry of lime to neutralize the fatty acids and form lime soap therefrom, continuing the heating and mixture to drive on the water and form a substantially completely dehydrated lime soap base with the mineral oil present, then adding to the dehydrated product at its elevated temperature a small proportion of an organic high boiling point stabilizer comprising a higher fatty acid ester of a polyhydric alcohol other than a triglyceride while continuing the then adding additional mineral lubricating oil while the temperature is permitted to drop slowly and the mixing is continued until the required amount of oil has been introduced to give the soap content desired, and finally drawing the lubricant in an anhydrous condition when the temperature has dropped below 200 F. V

12. The method in the manufacture of a substantially completely dehydrated lime soap lubricant free from glycerine which comprises heating and mixing together saturated higher fatty acids free from glycerides and mineral lubricating oil, adding a slurry of lime to neutralize the fatty acids and form lime soap therefrom, continuing the heating and mixing to drive oil the water and form a substantially completely dehydrated lime soap base with the mineral oil present, then adding a small proportion of substantially neutral lanolin to the dehydrated product at its elevated temperature while continuing the mixing, and finally adding additional mineral lubricating oil in stepwise portions while the temperature is permitted to drop slowly and the mixing is continued until the required amount of oil has been introduced to give the soap content desired in the dehydrated product.

.13. The method in the manufacture of a substantially completely dehydrated limesoap lubricant free from glycerine which comprises heating and mixing together saturated higher fatty acids free from glycerides and mineral lubricating oil, adding a slurry of lime to neutralize the fatty acids and form lnne soap therefrom, continuing the heating and mixing to drive oil. the water and form a substantially completely dehydrated lime soap base with the mineral oil present, then adding to the dehydrated product at its elevated temperature a small proportion of substantially neutral lanolin together with a small proportion of a higher boiling fatty acid ester of a polyhydric alcohol other than a triglyceride while continuing the mixing, then adding additional mineral lubricating oil while the temperature is permitted to drop slowly and the mixing is continued until the required amount of oil has been introduced to give the soap content desired, and finally drawing the lubricant in an anhydrous condition when the temperature has dropped i v 2,246,487 the heating and mixing to drive of! the water and form a substantially completely dehydrated lime soap base, then adding about 0.4-3.0% 01 substantially neutral lanolin and about 0.1-0.7% glyceryl monostearate to the dehydrated product at its elevated temperature while continuing the mixing, and finally adding additional mineral lubricating oil in stepwise portions while the temperature is permitted to drop slowly and the mixing is continued until the required amount of oil has been introduced to give the soap content desiredi the dehydrated product.

15. A dehydrated lime soap grease free from glycerine which is stable against oil separation and which does not break down when heated to temperatures at or above its melting point, comprising a naphthene-base mineral lubricating oil,

lime soap oi' higher saturated fatty acids, and

from 0.1 to 0.7% of glyceryl monostearate as a stabilizing agent.

16. A dehydrated lime soap grease free from glycerine which is stable against oil separation,

has a melting point of the order of 220 F. and above, does not break down when heated to temperatures at or above its melting point and is has a melting point 01 the order of 220 1". and above, does not break down when heated to temperatures at or above its melting point and is resistant to oxidation comprising a naphthen base mineral lubricating oil, from 0.1'to 0.7% of glycerylmonostearate as a stabilizing agent, and from 1 to 30% of lime soap of saturated iatty acids from hydrogenated fish oil having the following approximate composition:

Percent Myristic acid- 9 Palmitic acid 22 Stearic acid 27 Arachidic acidw 22 Behenic acid 20 18. The method in the manufacture or a substantially completely dehydrated lime soap lubricant free from glycerine which comprises saponifying a saturated higher fatty acid free from glycerides by mixing and heating with lime-in the presence of mineral lubricating oil to form lime soap, continuing the mixing while heating to a higher temperature of the order of 260-280 F.

' to substantially completely dehydrate the mixresistant to oxidation, comprising a naphthenebase mineral lubricating oil, lime soap of a mixv ture of saturated fatty acids from hydrogenated fatty oil, said mixture of fatty acids containing in excess of 40% by weight of saturated fatty acids higher in molecular weight than stearic acid,

and i'rom 0.1 to 0.7% of glyceryl monostearatei as a stabilizing agent.

1'7. A dehydrated lime soap grease free from glycerine which is stable against oil separation,