US2445936A - Waterproofing of lubricating greases - Google Patents

Description

atented July 27, 1948 WATERPROOFING 01F LRKCAG REASES Richard August Butcosk, New @rleans,

signer, by mesneassients, to Shell Developmerit Company, San Francisco, Caliit, a corporation of Delaware No Drag. Application April 27, R945, Se No. 590,713

The present nvention relates to the production of rust-proof water-repellent lubricating greases, and more particularly, to lithium and sodium soap lubricating greases carrying a rustprooflng agent, as for example, oil-soluble sulfonic compounds derived from the treatment of heavy hydrocarbon oils with strong sulfuric acid, said grease having incorporated therein a small proportion of a metal soap of 12-hydroxy-stearic acid, the metal component of said latter metal soap being selected from group 2 of the periodic classification of the elements, and preferably being magnesium, zinc or cadmium, the atomic weights of said metals having the ratio one to the other of approximately 24.3 to 65.4 to 112.4, said figures having been taken from pages 344 and 345 of the Handbook of Chemistry and Physics, 23rd edition, 1939.

Considering the wa er-proofing of lubricating greases from a theoretical standpoint, a waterproof grease is one which does not absorb or adsorb water when worked in the presence thereof. Since this is substantially impossible from the practical standpoint, lubricating greases are considered water-proof or water-repellent when a minimum amount of water is absorbed and/or adsorbed and the grease still, under normal working conditions, remains a firm grease, that is, does not break down and emulsify with water but remains stable.

Certain lubricating greases seem to be waterrepellant to a certain degree; that is, the lubricating grease will absorb or emulsify with a small amount of water and then refuse to combine with any further amount of water. However, greases under normal working conditions do not possess the property of preventing the water present in the grease from seeping between the lubricant and the metal base to which it is applied. The water functions to rust the metal base. In order to inhibit the grease from rusting said metal base, it is well-known to incorporate in the grease a rust-preventing or rust-proofing agent. However, all lubricating greases become very amount of water when worked in the esence of water and yet, remains a and stable "lubricant.

The present invention is particularly applicable to lithium soap and sodi soap lubricating greases, or, stated older-entity, to lubricating greases containing an alkali metal soap oi fatty acid, usually a saturated fatty acid, the alkali metal of which has an atomic weight varying between about are to about 23.6, these representing respectively the atomic weights of lithium and sodium. In general, the fatty acid which is combined with a lithium salt to form the lithium soap present in the grease has 12 or more carbon atoms and preferably, has 16 to 22 camera atoms or an even greater number, palmitic acid representing 16 carbon atoms and behenic acid representing 22 carbon atoms. There may also be present in said fatty acid soaps a small amount of unsaturated fatty acids as for example, oleic acid or ricinoleic acid. However, the most olesirable grease contains the lithium soap of the saturated fatty acids or the sodium soap of the saturated fatty acids. The invention is particularly applicable to lubricating greases containing lithium steal-ate soaps and sodium stearate soaps.

In addition to the lithium and sodium stearates,

water emuls'; able under working conditions when a rus-proofing agent is incorporated therein, and then cease to function as a stable lubricant.

If the lubricating grease is to successfully function under working conditions, not only must it act to prevent rusting of the metal base to which it is applied, but the lubricating grease must retain its lubricating property and remain firm and stable. In general, most of the rust-proofing agents which are added to lubricating greases the lubricating grease may contain small amounm of the fatty acid salts or soaps of other metals such as aluminum, barium, calcium, zinc and the like.

It is an object of the present invention to provide a rust-proofing composition for application to a rustable base, the latter composition comprising a spreadable carrier and a base-protecting medium such as oil. grease and the like, said carrier having present a rust-proofing agent which while inhibiting the rusting of a rustable base to which the composition is applied decreases the water-proofing characteristics of the composition, said rust-proofing composition carrying a metal soap of a lz-hydroxy-stearic acid which is present in an amount to substantially counteract the action of the rust-proofing agent in decreasing the water-proofing characteristics of the composition.

It is a further object of the present invention to rovide a. lubricating medium of the character set forth, and especially a lubricating grease comprising a carrier vehicle in which there is incorporated an alkali metal soap of a. fatty acid, said alkali soap preferably having an atomic characteristics of the grease.

accuses weight varying from a ut 6.94 to 23.0, said grease desirably containing an oil-solublerustproofing agent which while having the property of substantially inhibiting the rusting of a rustable base to which the grease is applied decreases the water-proofiing characteristics of the grease, the latter also having present a metal soap of a 12-hydroxy-stear-ic acid, the metal component of which appears in group 2 of the periodic classification of the elements and has an atomic weight between 24.32 and 112.4, said metal soap of 12-hydroxy-stearic acid being present in an amount to counteract the action of the rustprooflng agent in decreasing the waterproofing This grease may have present a mineral 011 base which may be a naphthenic base or a paraflinic base.

In accordance with the present invention, a lithium stearate lubricating grease, which is characterized by the properties of being rustproof and also water-repellent, may be prepared by forming a mixture of the following constituents:

Example 1 .eercent Hydrogenated fish oil 'l Zinc soap of 12-hydroxy-stearic acid 1 Sodium petroleum sulphonate prepared by treating heavy hydrocarbon oils with strong sulfuric acids, and then with sodium hydroxide or its equivalent 1.5

Lithium hydrate 1.1 57 vis. oil 89.3 Meta .phenylene diamine .1

In the above set forth lubricating grease, the

sodium petroleum sulphonate is the rust-inhibiting agent, and the zinc soap of 12-hydroxystearic acid is the water-repellent agent. It may be pointed out that the lithium stearate greases are waterproof or water-repellant, but are not rust-proof as determined by the "salt spray test" hereinafter referred to. In order to increase the rust-proofing property of the grease, there is added thereto a rust-proofing agent such as sulphonated petroleum produced as a sludge from treating crude petroleum with strong sulfuric acid, or the alkali metal salts thereof. The sulphonate may be a mono or di sulphonated aromatic and/or aliphatic molecule or salt thereof. When the rust-proofing agent is added to a lithium soap lubricating grease, the water-proof or water-repellent property of the grease is destroyed. However, if a small quantity of a metal soap of 12-hydroxy-stearic acid, and preferably, the soaps of 12-hydroxy-stearic acid hereinafter set forth, is incorporated in the grease, then the water-proof or water-repellent property of the lubricating grease is brought back. It is therefore clear that the rust-proofing agent decreases the water-repellent properties of the grease, but that this decrease is counter-balanced by the incorporation in the lubricating grease of a metal soap of l2-hydroxy-stearic acid, and preferably, of a cadmium, zinc or magnesium 12-hydroxystearic acid or mixtures thereof. The grease, the composition of which has been set forth in Example 1, may be prepared by placing in a kettle 25% of the total oil and the entire amount of the fatty acid which may be hydrogenated fish oil fatty acid, and the mixture is heated to a temperature varying between about 160 to 180 F. Then the entire amount of lithium hydrate in solution is added. The resulting mixture is then stirred constantly and as soon as the water has been removed and the soap formed by the interaction of the fatty acid and lithium hydrate begins to melt, more oil is added, and the addition thereof is continued until approximately 90% of the oil has been added. The grease at this stage is a fluid product, having been brought up to a temperature varying between about 380 to 390 F. or even higher. At this point it is desirable to adjust the neutrality number of the grease to zero or as closely to neutral as possible. At this stage the lithium soap should be neutral or, stated differently, at this stage the grease should be neutral. This neutrality is slightly altered after the petroleum sulphonate rust-proofiing agent and the metal soap of 12-hydroxy-stearic acid is added. Thereafter, the remaining 10% of the oil is mixed with the zinc soap of 12-hydroxy-stearic acid, and the mixture is introduced into the fluid lithium soap grease. Then the petroleum sulphonate is added, and thereafter, the inhibitor can be added. Thereafter, the hot grease, which usually has a temperature varying between 340 to 360 F. is drawn from the cooking kettle into a cooling rack which contains pans which are five feet long, two feet wide and five inches deep. The grease in these pans is about 4 inches thick and room air is blown across the pans at a minimum velocity of three feet per second. The grease present in the pans cools sumciently over a period of 12 hours to be milled and packaged. The grease will cool in the racks over a period of 12 hours from approximately 340 to 360 F. to approximately F.

The grease produced in accordance with Example 1 has the following A. S. T. M. penetration:

NumberoiStrokes,A.S.T.Mgr caseworker. 0 60 180 300 A. S. T. M. worked penetration 276 306 307 316 The grease is also characterized by the following properties:

The torque is determined by the U. S. Navy torque machine which consists of two McGill No. 214 bearings packed with the grease and cooled to 0 F., the assemblage being held at said temperature for 4 hours. Thereafter the force required to turn the inner race of the bearing by the means of a 1 horse power motor is measured. At the end of 5 minutes running period of the motor the torque measured is considered as the running torque value.

Medium steel panels are thinly coated with the grease of Example 1 and no corrosion is evident after the exposure of said grease and base to a 4% sodium chloride spray for hours, at room temperature, that is, around 60 to 90 F. The salt spray test subjects the coated iron or steel base to comparable conditions which exist at sea where the lubricating parts upon the gears of the guns are subjected to salt water, which is a solution of 4% sodium chloride, or to an atmosphere having a humidity of as much as almost 100% of salt water of 4% sodium chloride. Greases which are not rust-proof or which do not Possess the property of preventing rusting when applied to iron and steel surfaces will permit the salt spray to creep between the metal surface and the grease, and corrosion develops very rapidly, it being welllubricating grease not only a rust-proofing compound but also a water-proofing compound While the time of the "salt spray test" has been set forth as 100 hours, at room temperature. if

there is no rusting when the metal base coated with the grease has been subjected to the test for 20 hours or more, then the grease has been fairly well rust-prooied and water-prooied; and if there is no rusting oi the base after 50 hours or as high as 300 hours or more, the grease is considered to be a good grease from the standpoint of rust-proofing and water-proofing.

It is desired to state the oxidation resistance of greases is determined in the laboratory by empioying what is known as the "Norma Hofiman oxidation test. This is an accelerated test which greatly assists in determining what will actually occur when the grease or other lubricating medium is used in field operation.

The grease set forth in Example 1 had a pressure drop of 33 lbs. for an induction period of 100 hours.

The apparatus employed usually consists of a container having present an oxygen filled bomb containing small trays of the grease to be tested. The container has present an oil bath which maintains the bomb at a constant temperature. In order to accelerate the test, the grease may be mixed with copper or copper iead alloy filings. and ii desirable, the temperature of the bath can be raised. This will in a measure function also to increase the oxidation effect. When making the test. it is quite customary that there be mixed with the grease about 2 6% of copper lead alloy filings or some similar medium which increases the oxidation effect. The temperature at which the container is maintained will vary. but in general should be between 150 to 250 F.

The grease of Example 1 was tested in the "Norma Hohman oxidation bomb at 210 F. and

110 lbs. of initial oxygen pressure using a 20 gram sample on standard glass sample dishes, and showed a pressure drop of 3 lbs. for an induction period of 100 hours.

The grease oi Example 1 and the other greases herein set forth are characterized by the following properties:

Instead oi incorporating in the grease the zinc soap of iz-hydroxy-stearic acid, there may be added to the lithium grease or the sodium grease a metal soap of IZ-hydroxy-stearic acid, the metal component of which appears in group 2 of the periodic classification of the elements and which has an atomic weight varyin between 24.32 to 112.4 which includes the metals magnesium, calcium, zinc, strontium and cadmium. The results d obtained using calcium 12-hydroW-stcaric acid or strontium lz-hydroxy-stearic acid are mediocre compared with the results obtained by using magnesium, zinc or cadmium lz-hydroxy-stearic acids, and therefore, when adding the water-repellant agent to a lithium soap or a sodium snap, it is preferred that the metal component of the metal 12-hydroXy-stearic acid be selected from elements in group 2 of the periodic classification oi' the elements which have an atomic weight ratio of about 24.3 to 65.38 to 112.4, this preferred classification excluding calcium and strontium metals, the 12-hydroxy-stearic acid soaps of which do not give Very d results. Other examples of lithium stearate greases which carry a sulphonate water-proofing agent and a 'metal soap of 12-hydroxy-stearic acid functioning as a water-repellent agent are:

Example 2 Per cent Lithium stearate i7 sulphonate rust-proofing agent as specified- 3 Zinc soap of 12-hydroxy-stearic acid.. V Rosin it 57 viscosity oil 79 Water absorption 25 Example 3 Per cent Lithium stearate 1'! sulphonate rust-proofing agent as specified 3 Zinc soap of 12-hydroxy-stearic acid 1 Rosin 5'7 viscosity oil 78.5 Water absorption 25 Example 4 Per cent Lithium stearate 16 sulphonate rust-proofing agent as specified. 3 Zinc soap of lz-hydroxy-stearic acid.- Rosin "/2 57 viscosity oil 80 Water absorption 30 Example 5 Per cent Lithium stearate l5 sulphonate rust-proofing agent as specified- 3 Zinc soap of 12-hydroxy-stearic acid 2 57 viscosity oil 30 Water absorption 35 Example 6 Per cent Lithium stearate i5 sulphonate rust-proofing agent as specified- 3 Zinc soap of 12-hydroxy-stearic acid /2 Rosin A: 5'? viscosity oil 81 Water absorption 25 Example 7 Per cent Lithium stearate i1 sulphonate rust-proofing agent as specified-.. 2 Zinc soap of lz-hydroxy-stearic acid l. 57 viscosity oil 86 Water absorption 25 Example 8 Per cent Lithium stearate -11 sulphonate rust-proofing agent as specified. 2 Zinc soap of l2-hydroxy-stearic acid Rosin 3 57 viscosity oil 83% Water absorption 40 asaaaae Example 9 Per cent Lithium stearate 1i Sulphonate rust-proofing agent as specified- 2 Zinc soap of l2-hydroxy-stearic acid 2 5'7 viscosity oil 85 Water absorption 30 Example Per cent Lithium stearate 11 Sulphonate rust-proofing agent as specified 1 Zinc soap of IZ-hydroXy-stearlc acid 2 57 viscosity oil 85 Water absorption 30 Eicample 11 Per cent Lithium stearate 8 /2 Sulphonate rust-proofing agent as specified- 3 Cadmium soap of IZ-hydroXy-stearic acid 1 57 viscosity oil 87 Water absorption 30 Example 12 Per cent Lithium stearate 8 /2 Sulphonate rust-proofing agent as specified 3 Magnesium soap of lZ-hydroxy-stearic acid 1 5'7 viscosity oil 87 Water absorption d0 Grease remained firm under "salt spray test.

Greases containing sodium soaps of the fatty acids and particularly the sodium soap of stearic acid may have incorporated therein a rust-proofing agent and also a water-repellent agent so that when the grease is applied to an iron or steel base which is subjected to the action of the elements which normally induce corrosion, the latter will be prevented and the grease will retain, under working conditions, its firm and stable condition, that is, it will not emulsify, break down, or fall apart,

Sodium soaps of the fatty acids, as for example sodium stearate soaps, are water-soluble, and lubricating greases made therefrom are also watersoluble, and are not water-proof. It is desired to point out that a grease may be water-soluble but not water-repellant. The water-repellent grease is of the polar type which sheds water and also is substantially water-insoluble. Lubricating greases having present a sodium soap of a fatty acid may have a rust-proofing agent such as a petroleum sulphonate of the character hereindescribed incorporated therein, and may be made water-repellant by the addition thereto of a metal soap of 12-hydroxy-stearic acid, the metal component of said 12-hydroxy-stearic acid soap being a group 2 metal of the periodic classification of the elements and having an atomic weight varying between 24.32 and 112.41, this including the metals magnesium, calcium, zinc, strontium and cadmium, but preferably, is a group 2 metal, the atomic weights of which are in the ratio of about 24.3 to 65.4 to 112.1, the latter being the atomic weights of magnesium, zinc and cadmium which have proven to be the most satisfactory water-repellant agents for preventing greases containing sodium soaps of the fatty acids and a rust-proofing agent from breakin down under working conditions when subjected to the action of water or humid atmosphere containing water or aqueous compounds inducing corrosion such as dilute solutions of sodium chloride. Sodium soap greases which have been treated with a. metal soap of a 12 hydroxy-stearic acid will absorb only a small amount of water which will roll out of the grease upon further working. It may be stated that the lithium soap and sodium soap greases having present a rust-proofing agent including those of the character herein set forth, together with a metal soap oi 12-hydroxy-stearic acid of the character herein set forth and which have been worked, have a lower water absorption than the unworked greases.

The following is an example 01 a water-repellant rust-preventive sodium soap grease:

Example 13 Percent Sodium soap Of a fatty acid, preferably stearic acid Cadmium hydroxy stearate 5 Sulphonate rust-proofiing agent as specified- 3 57 viscosity oil The grease produced in Example 12 showed a water absorption of 30% and had a melting point of 318 F. When subjected to the Shell roll test the A. S. T. M. micro-penetration at the start of the roll test was 59 and after two hours was 84. When the grease was subjected to the salt spray test the base to which the grease was applied showed no corrosion after exposure to a 4% spray for hours at room temperature. Usually, in making the salt spray test," the coating of the grease on the base should not be more than 0.001 to 0.01 of an inch.

The Shell roll test is carried out as follows:

About 100 grams of grease is placed in a cylinder 7 inches long and 3 inches in diameter. A cylinder of smaller diameter weighing 11 pounds rolls inside the larger cylinder. The grease and the roller is placed inside the larger cylinder, and a motor turns the large cylinder at R. P. M. The grease is removed every two hours and tested to observe the break down or softening of the grease.

Additional examples of a sodium soap grease prepared in accordance with the present invention are:

Example 14 Percent Sodium soap of a fatty acid, preferably stearic acid Zinc lZ-hydroxy-stearic acid 3 Sulphonate rust-proofing agent as specified- 3 5'7 viscosity oil 82 Water absorption 35 Example 15 Percent Sodium soap of a fatty acid, preferably stearic acid 12 Cadmium 12-hydroxy-stearic acid 1 Sulphonate rust-proofing agent as specified- 3 57 viscosity oil 84 Water absorption 25 Referring to the incorporation of a rust-prooi-.

ing agent in the lithium and sodium soap greases herein set forth, as stated, the rust-proofing agent may be an oil-soluble sulfonic compound derived from the treatment of heavy hydrocarbon oils with strong sulfuric acid, or in the alternative, there may be used a soap of said oil-soluble sulfonic acids. These sulfonic acids are well-known in the art as possessing rust-proofing properties, and as set forth in expired U. S. Patent No.

1,630,101 granted to the Standard Oil Company of Indiana, May 24, 1927, and in other U. S. patents including Nos. 1,795,993, 2,023,367, 2,119,- 553, 2,182,992, 2,348,715 and 2,349,785. These suiphonates contain a polar type of molecule which is oil-soluble, and further, they possess the property of adhering to the metal to which they are applied, thereby preventing scumng or pushing away of the 011 films, Therefore, sulphonates keep the metal surfaces constantly covered with a him of the lubricant and also act as a rustprooflng agent. Various soaps of the sulphonates may be used including metal soaps such as sodium, lithium and calcium sulphonates. Lithium petroleum suiphonate is found to be a very satisfactory rust-proofing agent. Many of the other metal sulphonates are well-known in the art to act as rust-proofing agents when incorporated in a lubricating grease. However, lithiuzn petroleum sulphonate, that is, the lithium soap oi the product produced by reacting a lithiuin salt with the sulphonate resulting from the treatment of heavy hydrocarbon oils with strong sulfuric acid, is thought to be novel with the applicant. It has also been ascertained that organic amino oil-soluble sulphonates function satisfactorlly as a rust-proofing agent when incorporated in lithium soap and sodium soap greases when the molecular weight of said sulphonates approach the molecular weight of the oil. Short chain molecules are not as soluble in oil as the larger chain molecules. When the sulphonate derived from the treatment of heavy hydrocarbon oils with strong sulfuric acid is treated with sodium hydroxide, there results a sulphonate molecule which may be a mono or di substituted sulphonated aromatic or aliphatic molecule. The alkali petroleum sulphonates and the synthetic hydrocarbon sulphonates which give the best results are those which have an average molecular weight of 300 to 500, thereby tending to make the sulphonate quite soluble in both napthenic and paramnic base oils. Of course, the lithium soap and sodium soap greases contain a small amount of a metal compound of a 12-hydroxy-stearic acid, all as hereinbefore set forth.

Referring to greases containing lithium soaps oi the fatty acids, and preferably 3% to 25% thereof, the amount of sulphonate or a sulphonate soap such as the alkaline petroleum sulphonate soaps, may vary between 0.25% to Small amounts of sulphonate or the soap thereof in the grease, will only malte the grease rust-proof for a short period of time, that is, steel panels when coated with the grease will have only a short induction period when subjected to the "salt spray test before corrosion appears on the steel panel. Therefore, the most satisfactory limits are 1% to 3% of the metal sulphonate or the sulphonate resulting from the treatment of heavy hydrocarbon oils with strong sulfuric acid, or the organic sulphonates including the organic amino oil-soluble sulphonates. Amounts oi the rust-proofing agent greater than 10% will rustproof the grease and make a good product, but it is not economical.

In making lithium and sodium soap greases oi the character herein set forth water-proof, it is preferred to use 1% to 3% of a soap of the 12- hydroxy-stearic acids. The metal soaps of 12- hydroxy-stearic acid may comprise any of those herein set forth, but preferably, the magnesium, zinc and cadmium soaps. The amount of the soap oi the 12-hydroXy-stearic acid which is incorporated in the herein set forth lithium soap most and sodium soap greases may in general vary from about 0.5% to 10%. Amounts larger than 3% or 1% tend to lower the melting point of the grease and this is usually a disadvantage.

As the amount of sulphonate increases; and this term is used to cover not only the sulphonates per se, but the soaps thereof, the amount of the soap of lz-hydroxy-stearic acid present in the grease also increases. In general, it appears that when the lubricating grease contains smaller amounts of the soaps of 12-hydroxy-stearic acid then, the grease tends to lose its water-repellent property when the liquid grease is heated for too long a period. It is therefore preferred that nearly equivalent amounts of both ingredients be used, or the amount of the metal soap of 12-hydroxystearic acid present in the lubricating grease be slightly greater than the amount of sulphonate present.

Sodium base greases are diflerent in texture from that of the lithium base greases. Thesodium soap greases have a fibrous structure which requires a slightly larger amount of sulphonate than is used in the lithium base grease to yield the same value on the salt spray test. Further, the sodium soap base greases require slightly more metal soap or l2-hydroxy-stearic acid than sulphonates for mechanical stability, and therefore, in greases containing the sodium soaps of the fatty acids, the preferred ratio is 3 parts of sulphonate to 5 parts of the metal soap of l2-hy-- droxy-stearic acid, as for example 5 parts of cadmium hydroxystearate. Various examples have been set forth showing the difierent percentages of the rust-proofing agents and the soaps of 12-h'ydroxy-stearic acid. However, the preferred limits for the sodium base greases are 1% to 3% of the sulphonate, although, the general limit may be taken as 0.25% to 10%. In the sodium base greases the preferred range for the metal soaps of 12-hydroxy-stearic acid is 1% to 5%, although, here again, the general range may be taken as 0.5 to 10%.

It has been discovered that even if the greases containing a sodium soap of the fatty acids do not have a rust-proofing agent present that the rease may be made water-repellent by adding thereto a small amount of a metal soap of 12- hydroxy-stearic acid. the metal component of which appears in group 2 of the periodic classification of the elements, and which has an atomic weight varying from 24.3 to 112.4, but is preferably a metal in said group, the atomic ratio of which are 24.3 to 65.4 to 112.4. It has also been found that if to the sodium greases there is added a small amount of aluminum 12-hydroxy-stearic acid, the grease becomes water-repellent. By small amount is meant 0.5 to 10% and preferably, 1% to 3%. It is again emphasized that no rustproofing agent such as a sulphonate need be present in the grease containing the sodium soap of the fatty acids, although, in one form of the invention the rust-proofing agent is present.

Metal soaps of 12-hydroxy-stearlc acid may be prepared as follows:

(a) 500 pounds of 12-hydroxy-stearic acid are placed in a large wooden tank which contains 250 gallons of water.

(b) The water and acid are heated by a steam coil to a temperature of 190 to 200 F.

(c) A separate tank contains 73 pounds of sodium hydroxide and gallons of water. This mixture is maintained at a temperature varying from F. to F.

(d) Thereafter the sodium hydroxide solution acaaeae it is pumped into the tank containing the 12-hydroxy-stearic acid during the constant agitation of .the fatty acid solution.

(c) At this stage the wooden tank contains the sodium soap of the 12-hydroxy-stearic acid which is completely soluble in the hot water.

(1) In the tank which iormerly contained the sodium hydroxide, place 165 pounds of zinc sulphate and 200 gallons of water. This mixture is maintained at a temperature of about 120 F. and then it is pumped into the tank containing the sodium soap.

. (g) The nine soap is agitated for about 1 hour and permitted to remain in the wooden tank for 2 hours so the soap will float to the top of the tank, and thereafter. the water is drawn from the bottom of the wooden tank.

(h) The zinc soap is washed with warm water y itation and then allowed to stand for about two hours and again drawn. The soap is washed twice, pumped to a centrifuge and then sent on shallow trays and stored in a drying rack through which is blown warm air having a temperature varying between about 200 to 210 F. The powdered soap remains in the drying rack for about 48 hours. This zinc soap is now ready to be used in a grease. The yield .on the preparation of these soaps is 99.5

The lithium soaps and the sodium soaps which are incorporated in the greases which have a water-repellant agent and preferably a rust-profing agent present, may be prepared from fatty acids, glycerides or mixtures thereof.

The degree of water absorption of the grease as herein set forth is determined in a small water absorption apparatus which consists of a small cup into which is placed 20 grams of the grease, the latter being worked with a motor running at 1750 R. P. M. During a test run one milliliter (5%) addition of water is worked into the 20 grams sample of grease and the final reading is taken when an increment of water cannot be worked into the grease within a period of five minutes.

While the alkali soaps of oil-soluble hydrocarbon sulfonate give the most desirable results, other soaps may be used as for example, the barium or magnesium soaps of a hydrocarbon sulionate, it being pointed out that it is the hydrocarbon sulfonate group that is responsible for the rust-proofing action and not the metal radical or element which is combined with the hydrocarbon sulfonate group. While it is preferred that the rust-proofing agent in general be oil-soluble. fair results may be obtained by using a rust- Prooflng agent which is insoluble in the rustproofing composition or in the lubricating oil or grease. said insoluble rust-proofing agent bein ditslpersed throughout the rust-proofing composi on.

While the present invention is particularly applicable to lubricating greases. it is recognized that the principles of the present invention may be used .to provide a rust-proofing composition which may or may not be lubricating in character. From this standpoint, there may be provided a carrier medium or vehicle such as petroleum wax ceresin, ozokerite. degras, and in fact, any mineral. vegetable or animal base which has a spreadabie consistency and will adhere to a rustable base. Organic resins may also be used as a carrier medium provided said resins adhere to the iron or steel base which it is desired to rust-proof. In addition to using mineral oil sulfonic acids as the rust-proofing agent or alkali soaps thereof,

i2 suli'onated naphthenic acids may be used or soaps thereof such as the alkali soaps.

Any of the fatty acids normally used in the preparation of greases may be used in preparing the greases of the present invention, said fatty acids being set forth in the book entitled Lubrieating Greases, Their Manufacture and Use, by E. N. Klemgard, New York, 1937.

In the specification the percentages of the rustprooflng agents and the soaps of 12-hydroxystearlc acid are by weight and are based on the finished grease.

It is desired to point out that while it is preferred that the rust-proofing agent be oil-soluble, if the grease, lubricating medium, or other rustprooflng agent is water-proofed, it may be mixed with an oil-insoluble mist-proofing agent by mechanical means. What is desirable, if not almost necessary when using an oil-insoluble rustproofing agent, is that the mixture of the latter, the water-proofing agent and the grease, lubrieating medium or the material which it is desired to rust-proof and water-proof, be a homogeneous mixture. The cold mixing of a rustproofing agent may be carried out as follows:

Prepare the grease by heating the acid (7%) and base (1.1%) in the presence of about 25% of the total oil until a temperature of 350 to 370 F., then add the remainder of the oil and heat the mixture to 380 F. Adjust the mixture to nearly neutral or slightly basic, and then add the water repellant agent and after sufilclent time (15 to 30 minutes) is permitted for the solution to become homogeneous, the grease is poured in pans to cool. During the milling of the cold grease the oil-insoluble rust preventative may be mixed. However, the grease with the rust preventative and water repellant agent added during the hot processing makes a more satisfactory product.

While in greases it is necessary to use a metal soap of l2-hydroxy-stearic acid as herein specified since the soap gives body to the grease as well as acting as a water-proofing agent, in other mediums it is not necessary to use a metal soap. An ester of a 12-hydroxy-stearic acid may be used for other lubricating mediums or other rustproofing compositions which are not lubricating mediums, but the most satisfactory product is obtained when the metal soaps of 12-hydroxystearic acid are used as herein set forth. It is further desired to point out that it is not absolutely necessary that only the alkali metal soap of a fatty acid is present in the grease. Other soaps can be substituted for the alkali metal soaps of the fatty acid provided the substituted soap does not exceed 30% of the total soap present. In other words, for 0.5% to 25% of the alkali soap of the fatty acid present in the grease, about 30% thereof may be substituted by another soap such as a calcium soap, barium soap, lead soap, or the like, and, of course, the grease will also contain a metal soap of 12-hydroxy-stearic acid as herein set forth in detail. For example, the grease made in accordance with the present invention and containing a rust-proofing agent and a waterproofing agent and which originally had 10% of a sodium soap of a fatty acid, may have substituted for the 10% of the sodium soap, 8% of a sodium soap and 3% of a, calcium soap of a fatty acid or any equivalent acid usually used in the preparation of soaps for use in lubricants, Very satisfactory results are obtained in carrying out the present invention when the grease contains a mixture of a lithium soap of a fatty acid anda sodium soap oi a fatty acid, the lithium soap being present in a predominating proportion. For example, the grease may contain 8% of a lithium soap or a fatty acid, 2% sodium soap of a fatty acid. 3% of zinc iz-hydroxy-stearic acid, 1% cl an oil-soluble hydrocarbon sulfonate of the kind herein set forth, said percentage being applicable to either the hydrocarbon sulionate itself or the soap, particularly the alkali soap oi the oil-soluble hydrocarbon sulfonate and 08% oil, in general, throughout the present specification. the percentages of oil-soluble hydrocarhon sulionate and the metal soap thereof, and Particularly the alkali metal soaps thereof, are interchangeable.

I claim:

1. it lubricating grease consisting essentially of a major amount of an oil base having present a minor amount, sumcient to form a grease structure, of a metal soap or a fatty acid, at least 70% at said metal soap being an alkali metal soap at a fatty acid, said alkali metal having an atomic weight varying from about 6.94 to 23.0, from about l% to about 3% oi a hydrocarbon sulfonate, said sulfonate being present in an amount at least sumcient to inhibit rusting or a rustable base in contact therewith. which amount of the silhouette decreases the water-proofing characteristics of the grease, and a metal soap of a 12- hydrolry-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classification oi the elements and having an atomic weight between 24.32 and 112.4, said metal soap oi lfi-hydroxy-stearic acid being present in an amount of between about 1% and about 3% to counteract the action of the rust-proofing agent in decreasing the water-proofing characteristics at the grease.

2. A lubricating grease consisting essentially of a major amount of an oil base and a minor amount, sumcient to form a grease structure. oi an alkali metal soap of a fatty acid, said alkali metal having an atomic weight varying from about 0.94 to 23.0, from about 1% to about 3% at a hydrocarbon sulfonate, said sulfonate being present in amount at least suficient to inhibit rusting oi a rustable base in contact therewith. which amount of the sulfonate decreases the water-proofing characteristics of the grease, and a metal soap or a l2-hydroxy-stearic acid. the metal of said latter soap appearing in group 2 of the periodic classification oi. the elements, said metal soap or l2-hydroxy-stearic acid being present in an amount of between about 1% to about 3% to counteract the action of the rust-proofing agent in decreasing the water-proofing characteristics oi the grease. I

it. A lubricating grease consisting essentially of a major amount of an oil base, a minor amount. aumcient to form a grease structure of an alkali metal soap of a fatty acid, said alkali metal having an atomic weight varying from about 6.94 to 23.0; 0.25% to by weight of an oil-soluble hydrocarbon sulionate rust-proofing agent which while having the property of substantially inhibiting the rusting of a rustable base to which the grease is applied decreases the water-proofing characteristics of the grease, and 0.5% to 10% by weight of a metal soap of a IZ-hydroxy-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classification of the elements, said metal soap of IZ-hydroxy-stearic acid being present in an amount to counteract the action of the rust-proofing hydrocarbon sulionate in decreasing the water-proofing characteristics la or the grease, said percentages being taken on the weight 01 the lubricant grease.

t. A lubricating grease consisting essentially of a major amount of an oil base, a minor amount, suflicient to form a grease structure an alkali metal soap of a fatty acid, said alkali metal having an atomic weight varying from about 6.94 to 23.0; 0.25% to 10% by weight of an oil-soluble hydrocarbon sulfonate rust-proofing agent which while having the property of substantially inhibiting the rusting of a rustable base to which the grease is applied decreases the water-proofing characteristics of the grease, and 0.5% to 10% by weight of a metal soap of a lz-hydroxy-stearic acid. the metal of said latter soap appearing in group 2 of the periodic classification of the elements and having an atomic weight between 24.32 and 112.4, said metal soap of l2-hydroxy-stearic acid being present in an amount to counteract the action of the rustproofing agent in decreasing the water-proofing characteristics of the grease, said percentages being taken on the weight of the lubricating grease.

5. A lubricating grease consisting essentially oi a major amount of an oil base, a minor amount, sumcient to form a grease structure a lithium soap of a fatty acid, 0.25% to 10% by weight of an oil-soluble hydrocarbon sulfonate rust-proofing agent which while having the property of substantially inhibiting the rusting of a rustable base to which the grease is applied decreases the water-proofing characteristics of the grease, and 0.5% to 10% by weight of a metal soap of a l2-hydroxy-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classification of the elements, said metal soap of l2-hydroxy-stearic acid being present in an amount to counteract the action of the rustproofing agent in decreasing the water-proofing characteristics of the grease, said percentages being taken on the weight of the lubricating grease.

6. A lubricating grease consisting essentially of a major amount of an oil base, a minor amount. sumcient to form a grease structure an alkali metal soap of a fatty acid. said alkali metal having an atomic weight varying from about 6.94 to 23.0; 1.0% to 3.0% by weight of an oil-soluble hydrocarbon sulfonate rust-proofing agent which while having the property of substantially inhibiting the rusting of a rustable base to which the grease is applied decreases the water-proofing characteristics of the grease, and 0.5% to 10% by weight of a metal soap of a 12- hydroxy-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classiflcation of the elements and having an atomic weight between 24.32 and 112.4, said metalsoap of 12-hydroxy-stearic acid being present in an amount to counteract the action of the rustproofing agent in decreasing the water-proofing characteristics of the grease, said percentages beingtaken on the weight of the lubricating grease.

7. A lubricating grease consisting essentially of a major amount of an oil base, a minor amount, sufilcient to form a grease structure an alkali metal soap of a fatty acid, said alkali metal having anatomic weight varying from about 6.94 to 23.0; 1.0% to 3.0% by weight of an oil-soluble hydrocarbon sulfonate rust-proofing agent which whilehaving the property of substantially inhibiting the rusting of a rustable base to which the grease is applied decreases the water-proofing characteristics of the grease, and

0.5% to 10% by weight of a metal soap or a 1'2- acsaaae i5 hydroxy-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classiflcation oi the elements, said metal soap of 12- hydroxy-stearic acid being present in an amount to counteract the action oi. the rust-proofing, agent in decreasing the water-proofing characteristics of the grease, said percentages being taken on the weight of the lubricating grease.

8. A rust-proofing composition for application to a rustable base consisting essentially of a major amount of a spreadable oleaginous carrier and base-protecting medium carrying an oilsoluble hydrocarbon sulfonate rust-proofing agent in an amount of between about 0.25% to about 10% which while inhibiting the rusting of a rustabie base to which the composition is applied decreases the water-proofing characteristics of the composition, and a metal soap of a 12-hydroxy-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classification of the elements, said metal soap being present in an amount of between about 1% to about 3% to counteract the action of the rust-proofing agent in decreasing the water-proofing characteristics of the composition.

9. A rust-proofing composition for application to a rustable base consisting essentially of a major amount of aspreadable oleaginous carrier andbase-protecting medium carrying 1.0% to 3.0% of an oil-soluble hydrocarbon sulionate rustprooflng agent which while inhibiting the rusting of a rustable base to which the composition is applied decreases the water-proofing characteristics of the composition, and a metal soap of a l2-hydroxy-stearic acid, the metal of said latter soap appearing in group 2 of the periodic classification of the elements, said metal soap being present in an amount of between about 1% to about 3% to counteract the action of the rustprooflng agent in decreasing the water-proofing characteristics of the composition, said percentages being taken on the weight of the rust-proofing composition.

10. A rust-proofing composition for application iication of the elements, said metal soap being present in an amount oi between about 1% to about 3% to counteract the action of the rustprcorilng agent in decreasing the water-proofing characteristics of the composition, said percentages being taken on the weight of the rust-proofing composition.

11. The lubricating grease of claim 1 in which the alkali metal soap of the fatty acid is a lithium soap.

12. The lubricating grease of claim 3 in which the alkali metal soap of the fatty acid is a lithium soap.

13. The lubricating grease of claim 1 in which the alkali metal soap of the fatty acid is a sodium soap.

RICHARD AUGUST BUTCOBK.

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

UNITED STATES PATENTS Number Name Date 1,837,279 McGill Dec. 22, 1931 2,182,992 Lebo Dec. 12, 1939 2,184,952 Zimmer et a1. Dec. 26, 1939 2,283,602 Fiero May 19, 1902 2,307,852 Nothum Jan. 12, 1943 2,308,599 Fraser I Jan. 19, 1943 2,348,715 Adams May 16, 1944 2,350,688 Licata et al, June 6, 1944 2,380,960 Fraser II Aug. 7, 1945