US2487081A - Grease - Google Patents

Description

Patented Nov. 8, 1949 GREASE Reuben A. Swenson, Hammond, Ind., asslgnor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application November 28, 1947, Serial No. 788,692

16 Claims. 1

The present invention relates to block greases, and more particularly relates to high temperature greases of the driving journal and rod cup types.

The so-called high temperature greases of the type of driving journal compound and rod cup greases are usually applied in the form of a cake or block to the rotating shaft or bearing. Greases of these types are subjected to extreme pressure and temperature conditions and, therefore, must have high melting points in order to retain their shape and consistency at the elevated temperatures encountered in service; they must remain sufiiciently plastic for extended periods of time in order to insure proper lubrication and at the same time they must be moldable or pressable in order to be fabricated in the desired form of cake or block, and also dispensable in pressure gun-type lubricators. Greases of this type are soda soap greases containing from about 30% to about 60% soda soap of a fat or a mixture of a fat and fatty acid. An improvement in the preparation of greases of the herein described types was accomplished by incorporating in such greases a small amount'of a preferentially oilsoluble sulfonic acid soap, as described in my patent U. S. 2,352,811 of July 4, 1944. While greases prepared in accordance with teachings of this patent are satisfactory, it is necessary to use a fat, such as tallow or a mixture of fat and a fatty acid in making the soap stock. For various reasons, it is frequently advantageous to employ fatty acids as the sole soap stock instead of a fat or a mixture of-a fat and fatty acids. Heretofore, this has not been practical since greases made solely with fatty acids possess undesirable characteristics and properties, such as crumbliness, oil leakage, and excessive loss of consistency on working or pressing.

It is an object of the present invention'to provide a method of preparing high temperature soda soap greases having desirable pressing qualities. Another object of the invention is to provide an improved block grease made from fatty acids as the sole soap stock. Still another object of the invention is to provide a method of manufacturing a smooth short fiber high temperature soda soap grease from a fatty acid soap and a petroleum lubricating oil. Other objects and advantages of the invention will become apparent from the following description thereof.

Greases of the present invention comprise essentially an alkali metal soap of a long chain or high molecular weight fatty acid of at least 12 carbon atoms, and preferably the soda soap of Per cent by weight Alkali metal high molecular weight fatty acid soap 30 to 60 Alkali metal arylolate 0.1 to 10 Alkali metal oil-soluble sulfonate 1 to20 Glycerine 0 to 2 Hydrocarbon oil, remainder.

The alkali metal arylolate has the general formula TOM wherein T represents a monoor polycyclic aromatic nucleus corresponding, for example, to phenyl, naphthyl, etc., and 'M is an alkali metal. The aromatic nucleus T can be unsubstituted or substituted, for example, alkylsubstituted.

The alkali metal phenolate suitable for use in the present invention have the general formula:

c in which a, b, c, d,-e are selected from the group consisting of hydrogen, alkyl groups and mixtures thereof, the alkyl group having preferably less than 6 carbon atoms, and M is an alkali metal,

preferably sodium. Examples of suitable arylolates are sodium phenolate, sodium cresylate, sodium naphtholate, lithium phenolate lithium cresylate, etc.

Preferentially oil-soluble sulfonic acids employed in accordance with the present invention are preferably those obtained in the treatment of hydrocarbon oils, such as mineral or petroleum oils with strong acid, 1. e., concentrated or fuming sulfonic acid. However, for the purpose herein described, we can use other preferentially oilsoluble sulfonic acids, such as those obtained by the sulfonation of olefin polymers having at least about 22 carbon atoms in the molecule or those obtained by the sulfonation of alkylated aromatics having at least about 19 carbon atoms in the alkyl chain.

The preferentially oil-soluble petroleum sulfo-. nates are preferably those obtained in the treatknown 3 ment of petroleum oils to obtain highly refined products of the type of electrical insulating oils, turbine oils, medicinal white oils, technical white oils, etc., in which the petroleum oils are treated successively with a number of portions of concentrated sulfuric acid (i. e., above about 95% strength), or turning sulfuric acid. A variety of sulfur-containing compounds are formed by the chemical reactions of sulfuric acid upon the oil, including sulfonic acids, organic esters of sulfuric acid, partial esters of sulfuric acid, etc. Most of these compounds are relatively insoluble in the oil under the treating conditions and separate from the oil together with unreacted sulfuric acid as a sludge, which is separated from the 011 after each treatment. The sulfuric acid is usually added in "dumps" of about one-half pound per gallon of the oil, the total quantity of the acid added depending upon the oil being treated and the desired final product. Usually from about three pounds to about nine pounds of sulfuric acid per gallon of oil are used. Some of the sulfonic acids resulting from the treatment of the oil with the sulfuric acid are preferentially oilsoluble and remain in the oil layer after removal of the acid sludge. These can be removed from the oil by neutralizing the acid-treated oil with an alkaline agent, such as ammonia or an alkali metal hydroxid preferably sodium hydroxide, to form sulfonic acid soaps or. sulfonates which are then extracted from the oil by treatment with 50% to 80% aqueous alcohol solutions or other suitable means. Because of the characteristic mahogany color of these sulfonates they are in the petroleum art as mahogany soaps. While the majority proportions of the preferen tially oil-soluble sulfonatesare obtained from the acid-treated oil there can be recovered from the acid sludge, by suitable solvents, preferentially oil-soluble sulfonates or sulfonic acids. The term preferentially oil-soluble sulfonates therefore includes the oil-soluble sulfonates from both the acid-treated oil and the acid sludge.

While any of the preferentially oil-soluble sulfonates can be used, I prefer to employ those obtained from oil-soluble sulfonic acids having combined weights in the range of from about 350 to about 525, and particularly in the range of about 450 to about 500. The combining weights of the oil-soluble petroleum sulfonic acids vary with the viscosity of the oil being acidtreated and the total amount of sulfuric acid employed. To a certain degree the type of preferentially oil-soluble petroleum sulfonic acid obtained will also depend upon the type of crude oil from which the acid-treated oil is obtained. For example, the preferentially oil-soluble sulfonic acids obtained in treating a petroleum distillate having a Saybolt Universal viscosity at 100 F. of from about 60 seconds to about 230 seconds with 3 to 5 pounds of fuming sulfuric acid, have combining weights of about 430, while the preferentially oil-soluble sulfonic acids obtained when treating petroleum distillates having Saybolt Universal viscosities at 100 F. of from about 220 seconds to about 800 seconds with from about three to about nine pounds of fuming sulfuric acid per gallon of oil have combining weights of from about 470 to about 500.

Generally, I prefer to use preferentially oilsoluble petroleum sulfonates of the metals of group I of the periodic system, particularly sodium and potassium salts, although we may use sulfonates of metals of other groups of the periodic system or of ammonium or ammonia derivatives such as amines and the like.

' While as stated above, I can use metal salts of preferentially oil-soluble petroleum sulfonic acids having combining weights within the range of from about 350 to about 525, I prefer to use the metal salts of petroleum sulfonic acids havin combining weights within the range of from about 450 to about 500. Specifically, I have obtained excellent results with sulfonates of the type obtainable by treating petroleum distiilates of from about 200 seconds to about 800 seconds Saybolt Universal viscosity at 100 F. with from about three to about nine pounds of strong sulfuric acid, preferably fuming sulfuric acid per gallon of oil. The method of obtaining desirable soaps of preferentially oil-soluble sulfonic acids derived from petroleum oils is illustrated by the following examples which describe the preparation of a sodium soap of the preferentially oil-soluble sulfonic acids having combining weights of about 470 to about 500.

A petroleum oil distillate having a Saybolt Universal viscosity at 100 F. of about 650 seconds is treated with from about 3 to about 6 pounds of fuming sulfuric acid per gallon of oil in one-half pound increments or dumps." After the acid sludge from each one-half pound acid dump" is settled and withdrawn, the next one-half pound of fuming sulfuric acid is added to the oil. The temperature of the oil before the fuming acid is added thereto is maintained below about 60 F., but due to the heat of reaction upon addition of the sulfuric acid, the temperature of the oil may rise from about F. to about F. After the required total amount of fuming sulfuric acid has been added to the oil and the oil freed of acid sludge, the acid-treated oil containing oilsoluble sulfonic acids dissolved therein is neutralized with a solution of sodium hydroxide. The aqueous alkali solution is then separated from the oil solution containing dissolved therein sodium soaps of sulfonic acids and the latter separated from the oil by extraction with alcohol of about 60% strength. The alcohol layer containing dissolved sodium sulfonates is then separated from the oil and subsequently distilled to recover the alcohol and remove water. The crude sulfonic soap obtained in this manner contains from about 30% to about 60% sodium sulfonate, from about 30% to about 60% oil, from about 1% to about 10% water. and up to 10% inorganic salts which may be removed by the procedure hereinafter described.

The above procedure may be modified in that after the acid sludge is removed from the acidtreated oil, the 011 containing dissolved sulfonic acids is extracted with about 60% alcohol to remove the sulfonic acids which then may be neutralized with sodium hydroxide and subsequently freed of the alcohol by distillation.

A preferentially oil-soluble petroleum sulfonate of similar solubility characteristics can be obtained by similarly treating a Mid-Continent crude distillate oil having a viscosity of about 350 seconds Saybolt Universal at 100 F. with a total of five pounds of fuming sulfuric acid.

Soaps of preferentially oil-soluble sulfonic acids having similar combining weights and properties are obtainable by treating a distillate having a Saybolt Universal viscosity at 100 F. of from about 500 to about 850 seconds with about 6 to 9 pounds of fuming sulfuric acid per gallon of oil.

76 The crude soaps of these preferentially oilably alcohol of 60% to 70% strength, and allowing the salts to settle while maintaining the mixture within the temperature range of 180 F. to 175 F., preferably 155 F. to 165 F. When the salts have settled the supernatant alcohol-soap layer is separated and the alcohol is recovered by conventional distillation procedure. By this method of purification the salt content of the crude sulfonic soap can be readily reduced to or less, e. g., to about 3.5%.

The long chain fatty acids employed in preparing the soap stock can be unsaturated, partially unsaturated or saturated fatty acids, having. from 12 to 22 or more carbon atoms in the chain, such as, for example, lauric acid, palmitic. stearic, oleic, cotton seed fatty acid, animal fatty acids, standard fatty acids, behenic acid and hydrogenated fish fatty acids or the fatty acid pitch obtained therefrom, in accordance with the procedure demonstrated in U. 8. Letters Patent Nos. 2,229,367 and 2,229,368. The standard fatty acids is a product well known in the grease making trade and comprises about 40% animal fatty acids and about 60% cottonseed fatty acids.

The hydrocarbon oil constituent can be a synthetic or a natural hydrocarbon oil, such as a petroleum oil in the viscosity range of from about 80 seconds at 100 F. to about 300 seconds at 210 F. Saybolt Universal viscosity, the viscosity selected being dependent upon the intended use or service for the grease.

The greases of the present invention can be made at fire kettle temperatures, namely above 320 F. or by the steam kettle method at temperatures of 250-320 F., although the present invention is particularly adaptable to the preparation of fire kettle greases. In preparing the grease by the flre kettle method, all of the fatty acid, the alkali metal arylolate, e, g., phenolate, the oil-soluble sulfonate and a small amount of the hydrocarbon oil are charged to the mixture and heated to about 200-210 F. The alkali metal saponifying or neutralizing agent, such as caustic soda in a 48 Baum solution, is then added to the mixture and the mass gently heated with stirring until substantially dry, that is, practically all of the water has been evaporated from the mixture. The temperature of the batch is then raised to a temperature of from about 320 F. to about 380 F., preferably to about 350 F., the balance of the hydrocarbon oil added and the alkalinity adjusted to about 0.2% sodium hydroxide. The batch is then heated to a temperature of from about 530 F. to about 570 F., preferably to about 550 F. and maintained at this temperature until clear-and free of foam. Heating of the batch is then discontinued and the material cooled to a temperature not below about 300 F...

and preferably to a temperature of about 490 F. to about 510 F. for filling.

In preparing greases suitable as rod-cup lubriof from about 490 F. to about 510 F.. at which time the glycerine is added. As soon as the foaming, which usually takes place at this time, has subsided, and the batch is clear, it is ready for filling. If desired, a small amount, namely from about 0.001% to about 0.0001% of asillcone polymer may be added to inhibit foaming. In case a grease having longer fibers is desired, the grease is cooled to a temperature as low as 350 F. or 300 F., before it is filled.

Optionally, instead of adding the alkali metal arylolate, e. g., phenolate, to the mixture, it can be formed in situ, by adding the required amount of phenol, cresol, naphthol, etc. to the greasemaking mixture.

Greases made in accordance with the herein described invention have improved penetration and softening characteristics. Penetration is an indication of hardness and consistency and in the following data it has been based on the A. S. T. M. penetration test,- D217-38T. Softening time, on the other hand, is an index of quality from the service standpoint and is measured by the following described test. A cylinder of the grease, onehalf inch in diameter and about five-eighths inch long is heated on a metal plate contained in an oil or mercury bath. The temperature of the bath is controlled to give the desired temperature, usually about 340 F. at point of contact between the plate and the grease sample which is subjected to the weight of an 85 gram cylinder, thus providing a pressure on the driving journal compound comparable to the pressure to which the same is subjected in actual operation when it is forced by a spring against a hot bearing. Softening time is defined as the time in seconds required to flatten the test cylinder one-fourth inch under these conditions. If the test sample does not fiatten one-fourth inch at the end of ,300 seconds, the test is terminated and the amount the test sample has flattened noted; the result is expressed thus, for example, 300( which means at the end of 300 seconds the test piece flattened one-eighth of the total movable distance of inch. High temperature. greases made by the prior art methods usually have a softening time varying between about 80 seconds and cants, which are usually dispensed through pres- Penetration at 77 F Structure I Example l 2 3 Per cent Soda tallow fatty acid soap- Per cent Sodium Mahogany soap.-. 5 Per cent Sodium phenolate 2.4 Per cent Sodium cresylate Per cent Petroleum oil (8. U. Viscosity at 210 F.=200-210 secs.)

455g Softenin time at 340 F. g.

weighg 3000) Fair Very good 1 Grease is sticky on working; not pressable.

Examples 1 and 2 show the advantage of employing the alkali metal sulfonate in combination with the arylolate; making the grease with a sodium sulfonate but without an arylolate, as the grease of Example 3 resulted in a product which was not pressable.

If desired, the alkali metal phenolate can be used in combination with an alkali metal salt of a short chain organic acid of the type disclosed in my copending application, Serial No. 788,691,

' limitation.

filed November 28, 1947. Example 4' illustrates such a grease.

Example 4 Per cent soda tallow fatty acid soap 48.0 Per cent sodium mahogany soap 5.0 Per cent sodium formate 0.1 Per cent sodium cresylate 1.0

Per cent petroleum 011 (S. U/Viscosity at 210 F.=200-210 secs.) 45.9 Penetration at 77 F. 29 Softening time at 340 F. (85 gs. weight) 3001}; Structure Very good Pressabillty Very good Greases made in accordance with the present invention may contain small amounts of ingredients other than the essential components named herein. For example, there may be incorporated in such greases small amounts of an antioxidant such as a naphthol, phenyl alpha naphthylamine, etc, extreme pressure agents, such as halogenated hydrocarbons, mica, graphite, etc.

Percentages of greases herein and in the appended claims are weight percentages.

While I have described my invention with particular reference to certain preferred embodiments thereof, it is to be understood that these are by way of illustration and not by way of I claim:

1. A high temperature grease comprising from about 30% to about 60% of an alkali metal soap of a high molecular weight acid of at least 12 carbon atoms, from about 0.1% to about 'of an alkali metal arylolate, from about 1% to about of an alkali metal soap of a preferentially oil-soluble sulfonic acid and a hydrocarbon oil.

2. A high temperature grease comprising from about to about 60% of an alkali metal soap of high molecular weight fatty acids of at least 12 carbon atoms, from about 0.1% to about 10% of an alkali metal phenolate, from about 1% to about 20% of an alkali metal soap of a preferentially oil-soluble sulfonic acid and a hydrocarbon oil.

3. A high temperature grease comprising from about 30% to about 60% of an alkali metal soap of a high molecular weight fatty acid of at least about 12 carbon atoms, from about 0.1% to about 10% of an alkali metal phenolate having the general formula:

C a o in which a, b, c, d, and e are selected, from the group consisting of hydrogen, alkyl groups of less than 6 carbon atoms, and mixtures thereof, and M is an alkali metal, from about 1% to about 20% of an alkali metal soap of a preferentially.

oil-soluble sulfonic acid, and the remainder hydrocarbon oil.

4. A high temperature grease as described in claim 3 in which the alkali metal is sodium.

5. A high temperature grease as described in claim 3 in which the high molecular weight fatty acid is tallow fatty acids.

6. A high temperature grease as described in claim 3 in which the highmolecular weight fatty acid is stearic-acid.

7. A high temperature grease as described in claim 8 in which the high molecular weight fatty 8 acid is a mixture of animal fatty acid and vegetable fatty acids.

8. A high temperature grease as described in claim 3 in which the phenate is sodium phenolate.

9. A high temperature grease as described in claim 3 in which the phenolate is sodium cresylate.

. 10. A high temperature grease of the rod cup type comprising from about 30% to 60% of an alkali metal soap of a high molecular weight fatty acid of at least about 12 carbon atoms, from about 1% to about 20% of an alkali metal soap of a preferentially oil-soluble sulfonic acid, from about 0.1% to about 10% of an alkali metal phenolate, from about 0.1% to about 2% glycerine and the remainder a hydrocarbon oil.

11. A high temperature grease as described in claim 10, in which the high molecular weight fatty acid is tallow fatty acids.

12. A high temperature grease as described in claim 10 in which the alkali metal phenolate is sodium cresylate.

13. A high temperature grease as described in claim 10 in which the alkali metal phenolate is sodium phenolate.

14. The method of preparing a high temperature grease comprising about 30% to about 80% of an alkali metal soap of high molecular weight I fatty acids, from about 1% to about 20% of an alkali metal soap of a preferentially oil-soluble sulfonic acid and about 0.1% to about 10% of an alkali metal phenolate having the general formula in which a, b, c, d, and e are selected from the group consisting of hydrogen, alkyl groups of less than 6 carbon atoms and mixtures thereof and M is an alkali metal, and the remainder a hydrocarbon oil comprising the following steps: mixing all of the high molecular weight fatty acids, the phenolate, and the oil-soluble sulfonates and a small amount of a hydrocarbon oil in a mixer and heating the same to about ZOO-210 F., adding an aqueous solution of an alkali metal saponlfying agent, stirring the mixture until substantially all of the water is evaporated therefrom, raising the temperature of the mixture to about 320 F. to about 380 F., adjusting the alkalinity of the mixture to an excess of about 0.2% alkali, heating the alkalinity-adjusted mixture at a temperature of from about 530 F. to about 570. F. until the mixture is clear and free of foam, cooling'the mixture to a temperature not below about 300 F., and filling the same.

I 15. The method of preparing a high temperature grease comprising about 30% to about of an alkali metal soap, a high molecular weight fatty acid containing at least 12 carbon atoms. from about 1% to about 20% of an alkali metal soap of a preferentially oil-soluble sulfonic acid, from about 0.1% to about 2% glycerine, from about 1% to about 10% of an alkali metal phenolate having the general formula in which a, b, c, d, and e are selected from the group consisting of hydrogen, alkyl groups of less than 6 carbon atoms and mixtures thereof and M is an alkali metal. and the remainder a hydrocarbon oil comprising the following steps: mixing all of the ,high molecular weight fatty acids, the alkali metal phenolate. the alkali metal oil-soluble sulionate and a small amount of the hydrocarbon oil in a mixer and heating the same to about 200-210 F., adding an aqueous solution of an alkali metal saponifying agent and stirring the mixture until substantially all of the water is evaporated therefrom, raising the temperature of the mixture to about 320 F. to about 380 F.. adjusting the alkalinity of the mixture to an excess of about 0.2% alkali, heating the alkalinityadiusted mixture to a temperature of from about 530 F. to about 570 F. until the mixture is clear and free of foam, cooling the mixture to a temperature of 490-510 F., adding from about 0.1%

10 to 2% glycerine and filling the grease when subsatntially all of the foaming has subsided.

16. The method of preparing a high temperature grease as described in claim 15 in which the grease is filled at a temperature below about 490 F. and above about 300 F. after the glycerine is added to the grease mixture.

REUBEN A. BWENSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,031,986 Stratford Feb. 25, 1938 2,065,857 Hilliker Dec. 29, 1938 2,182,137 Ricketts Dec. 5, 1939 2,303,558 Kaufman Dec. 1, 1943 2,352,811 Swenson July 4, 1944 Certificate of Correction Patent No. 2,487,081 November 8, 194a REUBEN A. SWEN SON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 46, for sulfonic read sulfuric;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 21st day of March, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gommz'aszoner of Patents.

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