US2002819A - Grease and its manufacture - Google Patents

Description

Patented May 28, 1935 PATENT OFFICE GREASE AND ITS MANUFACTURE Gus Kaufman, Beacon, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware ,No Drawing. Application August 15, 1931,

Serial No. 557,384

8 Claims.

This invention comprises a method of heat treating oils. used in the preparation of lubricating greases, and particularly heat treating a mixture of a mineral oil and a soap forming material, such as a fatty oil, fatty acid and the like, and also the products resulting from such treatment; following the heat treatment the mixed oils may be subjected to saponiiication to pro-' duce the desired lubricating grease.

Broadly; my invention contemplates the preparation. of grease or lubricating compositions composed mainly of hydrocarbon oil and a soap prepared and combined in such a manner that the physical properties of the resulting grease, such as melting point and hardness, may be varied to a considerable extent substantially independently of the soap content.

The invention contemplates an improved method of manufacture of grease compositions wherein the hydrocarbon oil and fatty oil ingredients are preliminarily heated, preferably in admixture, under various conditions of temperature or during various periods of time at various temperatures in order to effect a digestion or conversion. The extent of this conversion may conveniently be controlled by regulating the increase in viscosity to a predetermined point. When the desired extent of conversion has been effected, al kaline material is added to react with the saponifiable constituents of the digested oil mixture to form a final product of desired physical and chemical characteristics.

It has been common in the prior grease making art to heat the mineral oil or hydrocarbon and fat or fatty acid together to the desired temperature for carrying out saponification, which might have been in some instances as high as 400 to 500 F. The aqueous solution of saponifying agent was then added without further delay in such regulated quantities that the water would be flashed off continuously, thus avoiding the possibilities of boil-overs due to excessive foaming. The time of manufacture of a batch was also materially reduced by this method. I

According to the present invention the mineral oil and fat or fatty acid are not only heated together to a high temperature but they are maintained at a high temperature for a substantial period during which the aforementioned increase in viscosity occurs. In the light of the prior art method this heating may be said to be needlessly prolonged.

The physical and chemical properties of greases made according to the methods of the prior art are largely dependent upon the nature of the ingredients used in their preparation. Thus it has been customary, for example, to control the hardness of grease by varying. the soap content, the hardness of the grease as commonly prepared usually being roughly directly proportional to its soap content.

Even when very high melting point or high titer fats are employed in the preparation of a hard grease by the prior art methods, the soap content of the resulting product may very greatly exceed that of my product havin" the same hardness and prepared from lower melting point fats.

By following the method of my invention an improved grease is produced, certain of the characteristics of which maybe varied at will, but generally speaking one which has amelting point appreciably lower than that of grease of corresponding hardness manufactured by conventional methods of practice from substantially similar type ingredients. Greases made by employing my invention may contain materially lower proportions of soap than greases prepared by the prior art methods. In other words, if it is desired to produce a grease having a certain consistency or hardness the soap content necessary to attain such consistency or hardness may be reduced to any desired extent up to 30 to 50% less soap and in some instances considerably greater reduction by the use of my invention. As a consequence of this the resultant grease will contain a larger proportion of hydrocarbon or lubricating oil, thus tending not only to very materially increase the lubricating qualities but also to greatly reduce the cost, inasmuch as a portion of the more expensive soap ingredient will have been replaced by the less expensive mineral oil ingredient.

Likewise it has been found that lower viscosity lubricating oils may partially or wholly replace higher viscosity lubricating oils in the preparation of greases by my method, while attaining the same consistency or hardness as when using the more viscous oils. By the substitution of lower viscosity oils for higher viscosity oils while maintaining a given consistency or hardness, considerable advantages have been experienced in reducingthe frictional resistance on account of the presence ofthe lower viscosity lubricating oil. Broadly speaking, my invention contemplates the preparation of lubricating compositions or greases, having desired lubricating and other physical properties, which may be composed of mineral and fatty oil or fatty acid ingredients of varying nature and physical characteristics and wherein the physical properties of the final product, particularly its consistency or hardness, may substantially be controlled irrespective either of its soap content or of the particular type of mineral or fatty oil used in its preparation. The petroleumor hydrocarbon lubricating oil constituents may be of the nature of a cylinder oil or cylinder stock and may embrace either a distillate or a residual product derived from either paraflin or naphthene base, or mixed paraflin and naphthene base crudes, or on the other hand may be of the nature of a pale oil or a fraction of lower boiling range than cylinder oil though derived from any of the foregoing crude sources. The fatty oil or fatty acid may be derived from either animal or vegetable origin, such as hard tallow, tallow oil, fleshing grease, stearin, elaine oil, castor oil, cottonseed oil, residual pitchy material resulting from the destructive distillation of fatty oils and fatty acids, and the like and may also embrace hydrogenated fats.

Such organic materials, being adapted upon treatment with a base to form soaps, are desig-- nated in the appended claims as soap forming materials.

The general procedure followed in preparing lubricating compositions in accordance with my invention is as follows: The hydrocarbon or mineral lubricating oil and fatty oil ingredients are mixed in suitable proportion, depending upon the quantity of these ingredients desired in the final product and are heated to a desired digestion or conversion temperature. During this heat treatment the oils are preferably continuously stirred. This temperature of treatment may range from approximately the melting point of the resulting grease, as for example 400 F., or even lower, to upwards of 600 F. The heated mixture of oils is then maintained substantially constant at the desired temperature for a predetermined period of time or until the mixture attains a desired degree of digestion or conversion, preferably determined by a progressive increase in the viscosity of the mixture. The digested mixture is then saponified in the usual manner by addition thereto of a suitable alkaline material such as caustic soda, lime, or the like, either with or without prior cooling of the digested mixture.

Although it is usually preferable to subject the petroleum and fatty oil ingredients to heat treatment after mixing, it is contemplated that these ingredients may be separately subjected to heating or digestion with subsequent mixing while in a heated state prior to saponification for the production of certain lubricating compositions.

While the exact nature of the physical and chemical changes occurring during digestion of the mixture has not been determined, apparently certain newi'compounds or products of reaction are formed which impart desirable qualities, especially that of hardness, to the resulting final product and which may be formed as the result of reaction duringdigestion or conversion, between the mineral and fatty oil, between constituents thereof, orbetween compounds or products formed as a result of conversion or partial decomposition of the fatty and mineral oils during. the heat treatment or as the result of a combination of'such reactions. These reactions may result in part at least from oxidation of the hot mixture resulting from the contact of the atmosphere with the surface of the mixture, or the mechanical stirring into the mixture of some of the air over it. This theory is strengthened by reason of the fact that it has been found that the desired increase in viscosity, and resulting increase in the hardness. of the final grease, is

determined by the change in viscosity of the digesting mixture.

The oil mixture is preferably heated to the desired digestion or reaction temperature as rapidly as possible in a conventional type grease kettle,

after which it may be maintained substantially constant at the desired temperature until the mixture has attained a predetermined viscosity.

It is desirable to eifect more or less constant agitation of. the mixture. Thus the mixture may be raised to a relatively low temperature, for example from 400 F. to 480 F., and be maintained at substantially this temperature for a relatively long period of time, while on the other hand the oil may be heated to a relatively higher temperature, ranging from 500 F. to 700 F. or even higher, at which temperature it may be maintained for a relatively short period of time in order to bring about the desired degree of conversion.

When heating or digestion is completed, saponification-may be brought about by the addition of caustic soda or other suitable soap forming chem icals to the digested or reacted mixture, preferably without prior cooling of the mixture. On the other hand, cooling may be desirable prior to the addition of the alkaline or basic material depending upon the temperature of the heat reacted mixture, in order to prevent excessive foaming or frothing during its addition. The saponifying agent is preferably added very slowly with continued agitation of the contents of the kettle in order to avoid excessive frothing or foaming.

Upon completion of saponification the resulting grease preferably is drawn in a molten con-v dition into suitable containers to cool.

removal of the finished grease from the kettle in However,

to limit the invention to the particular proportions, ingredients,or operating conditions'recited. In these specific examples the penetration or hardness of the resulting grease is expressed in each instance in terms of tenths of a millimeter penetration of an average sample as determined by the standard A. S. T. M. penetrometer and method for greases, and also with the same apparatus modified to the extent of havingan extra weight of 475 grams placed within the penetrometer cone. Such latter reading will be termed Penetration (Modified A. S. T. M.) This modified penetration test has been used on samples of relatively hard products to penetrate more deeply and give a higher and perhaps more accurate reading than that obtained with the same apparatus without the added weight.

Samples 1. 2 m

- by increasing the period of heating-the mixed while in Example 3 it was 21% hours. The greases resulting irom'subsequent saponiilcation, it will be observed. have modified A. S. '1. .M.

penetrations of 86, 105 and 176. respectively.

Examples 4, and 6 Cylinder trek (secs. viscosity Say- It at 2 F.)

Per cent- Time of heating oil and [at mixture beiore saponiiication:

to heat to 486 F Hours maintained 485 IL. viseosgz oli )mlxture (secs. Saybolt at Before heating Alter heating l Baponiiication. with caustic soda solution (40% NaOH) consisting oi. flake caustic and Water: Home required to add solution r Analysis of the ilnal product-per cent,

y weight:

Melting l" Pgmetra on LB. '1. M. mothod)...... I.enetmtion modiiled A. S. 'l. M.)-.

3.&

" The resultsoi Examples 4, 5 and 0 show that oil and fat the percentage of soapdn there+ 1 3 3 suiting greases may be reduced very consider ably, while still maintaining'practically the same mu hardness or penetration. These examples clearly 5 ylin d e r stock (secs. viscosity fleybolt H illustrate the possibility of increasing the content gmntujijjj use 6'1, 61.18 of mineral oil lubricant and decreasingthe soap w: content, thus lowering the cost of the flnal prod- {;;6:;;; ,-;r not while still maintaining the desired pen'etraxag l tion or hardness. v

m' t 3.02 3.41 0.30 I Timeoili tingoilandiatmixtunbeiore 3mm?! 7 m 3 saponiflmtion' J Hourareqniredtoheatiofltl" a 4 2% 'Hours maintained 31 20% 21% 7 8 Yisoosityoi (secs. Ssybolt at 210' -imam' no 100 100 Ingredients After heating 165 154 140 iinderstoclrisemviscosity Saybolt at 210F 151 103 Baponincation with caustic soda solution er eent-.; 37.37 -39. 78 (40% NaOH) consisting oi flake Paraflin distillate (372 m'viseosity-Boybolt at caustic and water: 100 F.): Hours required to add solution 4% 4 4% Per cent; 22. 00 94. 36 Analysis oi the ilnal product-per eent Hard tallow a by weight: Per cent. 29. 20 2B. 10

t 0.10 2.50 1.50 acid. 0

None None None Per Mnt 3.25 2.90 saso 30.00 01.00 Flake museum mom: 02.02 04.92 00.00 Per cent. s04 an I 1.51 am 2.41 Water' I 0.80 None 0.55 Per oent ..L 3.04 3.43 0.44 am None 'limeoi' heating on and m mum belore seponi- Ph 1011 mpertiesoiflnalproduct ny l umd" toast to485'! 4 0 '0 film? up n 04s 300 337 Hours maintainedat485 r ..-..'..'.'I.' '.'.'.'.'.'.'I.'II 7- n Penetrat n (A. B. '1. M. method) 41 47 84 Viscosity oi mixture (eees.-Saybolt at 210 2.): Penetration(modifled a.s.'r.m.)..-. as 100 110 Baruc .10 7s Mterheating..-.. 104 111 Saponiiication with caustic soda solution (49% p .v

Examples 1, 2 and 3 demonstrate myinvention i 1 km 4% W by indicating the variation in hardness or pene- ,pfly3is f theflnal mdW&IB eiin? tration in the resulting greases by varyin the lg'gg g g, Q2 3 time of maintaining the mixed oil and fat at high Sodium soap..-..----. temperature. The same oil and fat are employed in approximately the same proportions in each example. In Example 1 the mixture of oil and fat was maintained at the high temperature for f! pmpetmg 0mm! a period of 31 hours prior to saponiflcation; in Example 2 the period of heating was 26% hours,

Examples 7 and 8 resulted in relatively hard greases adapted primarily for the lubrication of locomotive driving journals. The mineral lubrieating oil used consisted of cylinder stock and a paraflln distillate commonly known in the industry as heavy red parafiln, the calculated viscosity of the-mixed oils being about 90 and 93 seconds Saybolt at 210 F., respectively. The fats used were tallow and a small amount of stearic acid and, after heating the mixed fat and lubricating oil to a temperature of about 485 F. for the desired periods of time and saponiflcation, greases were produced having nearly the same penetration, while the soap contentby actualanalysis was at least 5% lower in Example 8 as compared with Example 7.

' greases made by the usual prior art methods and therefore containing larger quantities of soap and a lesser quantity of mineral However, the inventionis also well adapted to enable the manuiacture oi softer usually prepared from low viscosity mineral oils, such as soft cup greases,

sponge grea'ses, and the like, and which may con- 15 tain lime, aluminum or other suitable soaps. The inclusion of such additional constituents as graphite, rosin, wax and the like, to impart certain specially desired physical properties to the product is not precluded.

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.

I claim:

1. A product resulting from the heat treatment of a mixture of a mineral lubricating oil and a soap forming material and having a viscosity Saybolt at 210 -F. at least 20% greater than that of the mixture of fresh untreated materials.

2. A product resulting from the heat treatment of a mixture of a mineral lubricating oil and a soap forming material characterized by having anincreased. viscosity over that ot-the freshly mixed materials and further characterized by producing upon saponiflcation and cooling a resultant finished mineral oil-soap grease having a penetration at least 20% less than the penetration of a finished grease resulting from blending the oil and the soap,- prepared from the fresh soap forming material, in the same proportions.

3. The method of preparing a soap-mineral oil grease which comprises heating a soap-forming material with mineral oil to a temperature at which an increase in viscosity of at least 20% may occur, efiecting a predetermined increase in the viscosity of the mixture of at least 20% by proa longing the heating at such temperature, and

then effecting saponiflcation and cooling to produce a grease.

4. {I'he method of preparing a soap-mineral oil grease which comprises heating a soap-forming material with mineral oil to a temperature upwards of 400 F., efiecting a predetermined increase in the viscosity of the mixture of at least 20% by prolonging the heating at such temperature, and then saponiiying the mixture and cooling to produce a grease.

5. The step in the method of preparing a soapmineral oil grease which comprises heating a soap-forming material with mineral oil to a temperature upwards of 400 F.,- and maintaining such temperature until an increase in the viscosity of the mixture of at least 20% is attained.

6. The step in the method of preparing a soapmineral oil grease which comprises heating a soap-forming material with mineral oil to a temperature at which an increase in viscosity of at least 20% may occur, and maintaining such temperature until a predetermined increase in the viscosity of the. mixture of at least 20% is attained.

7. The step in the method of preparing a soapmineral oil grease which comprises heating a soap-forming material with mineral oilto a temperature at which an increase in viscosity of at least 20% may occur, and maintaining such temperature while exposing the mixture to. contact with air until a predetermined increase in the viscosity of the mixture of at least 20% is attained.

8. The method of preparing a soap-mineral oil grease which comprises heating a soap-forming material with mineral oil to a temperature upwards of 400 F., efiecting a predetermined increase in the viscosity of the mixture of at least 20% by prolonging the heating at such temperature while exposing the mixture to contact with air, and then saponifying the mixture and cooling to produce a grease.

GUS KAUFMAN.

CERTIFICATE OF CORRECTION.

-' Patent No. 2,002,819. May 28, 1935.

6113' KAUFMAN.

It is hereby certified that error appears in the printed specification of the above nuninered patent requiring correction as follows: Page 1, first column, beforeline I, insert the following paragraph;

-. This application is a continuation in part of my eopending application filed July 1, 1930, Serial No. 465, 143;

And that thesaid Letters Patent should be read with this correction therein that the same may conform to the record of the. case in the Patent Office.

Signed and sealed this 13th tiayof August, A. D. 1935.

Leslie Frazer (Seal) I I I Acting Commissioner of Patents,