US2487377A - Lubricant - Google Patents

Description

Patented Nov. 8, 1949 LUBRICANT Theodore G. Roehner, Mount-Vernon, and George W. Murray, Pleasantville, .N. Y., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application April 1'7, 1948, Serial No. 21,756

: Claims. (01. 252-421) V This invention relates to lubricants and, more particularly, is concerned with lubricants characterized by a high order of effectiveness under severe operating conditions.

It is well known that lubricants generally lose some or all of their effectiveness when subjected to high temperature and pressure conditions, and this is particularly true of greases exposed to such conditions. In lubricating machine parts with a grease, it is essential to provide a grease which will substantially retain its character un- -der the foregoing conditions. Failure to do so results in high consumption of the lubricant and frequent servicing. In general, available greases suffer from a marked tendency to change-in character when used over a wide range of temperature. For example, the consistency of a conventional grease is prone to change over a Wide range of temperature. Certain soda base greases, for

example, have a pronounced and undesirable property of changing from a short to a long fibre structure with temperature change. Some conventional greases are also characterized by excessive softening when exposed to elevated temperatures, thereby being extruded too rapidly from the area being lubricated to provide efficient lubrication. "In addition, some greases tend to lose their oil content when used at elevated temperatures and pressures. This condition is generally referred to in the art as bleeding.

In accordance with the present invention, there has now been discovered aggrease which is char .acterized by a high order of effectiveness wider severe operating conditions and which is substantially free from the shortcomings discussed above. "The greases contemplated herein contain, as a characterizing or reinforcing agent. a small amount of a -water-dispersible or oil-insoluble and water-soluble proteinaceous material, representative of which are the water-dispersible proteins and high molecular weight amino acids derived therefrom by hydrolysis. Typical of the proteinaceous materials contemplated as reinforcing agents in the greases of this invention .are casein, gelatin, arginine, aspargine, and the albumins, .such as egg albumen and the like. While use of one :or more of the above substances represents a preferred embodiment of the invention, it .is likewise contemplated that other water-dispersible pnoteinaceous material-s known in the .art

2 may be employed in improving the heat resistant characteristics of the greases described herein.

The greases of this invention containing one or more of the aforesaid characterizing agents are the alkali metal and alkaline earth metal base greases; that is, those grease compositions consisting of mineral oil in admixture with alkali metal or alkaline earth metal soaps of fatty acids .or with a sufficient proportion of such soaps'preslent to give the characteristics usually recognized as attributable to alkali and alkaline earth metal base greases. The soap content of these greases is generally between about '10 and about per cent by weight on the basis of the final product. They are generally prepared by heating a fat .or a fatty acid, or a mixture thereof, with a mineral :oil and thereafter heating the resultant mixture with the desired metal hydroxide at elevated temperatures $0 obtain a substantially anhydrous metal base grease. The final product so obtained generally contains 8.5 to 48 per cent "fat or fatty .acid; 1.5 to 7.5 per cent metal hydroxide (dry basis) and 29.5 to 89.5 per cent mineral oil. In obtaining the grease, the mixture may be cooked, {for example, at temperatures of 250 to 400 F. Available steam-cooked greases do not maintain their shape at elevated temperatures and firecooked greases are typified by bleeding under such conditions;

The mineral oil constituent of the greases contemplated herein may vary considerably in character and includes residual or distilled oils. Preference is accorded, however, to oils having a viscosity of '(S. U. V.) of to 250 seconds at 210 F. Similarly, the fats and fatty acids which may be used are those generally found in the soap type greases. Representative of such materials are vegetable, animal, and fish fatty oils, and hydrogenated fatty materials thereof. While sodium ydroxide calcium hydroxide are preferred in viewof cost considerations and a greater demand by industry for :soda and lime base greases, other metal hydroxides may be used in the present greases, preferably where'the soapeconstituent of the grease is prepared by directsa-ponification in aqueous phase. Accordingly, such other metal hydroxides as those of lithium, potassium, magnesiumj, barium, strontium, etc, are contemplated herein, with the alkali :metal hydroxides pretened.

It has been found, in accordance with this invention, that from one to two parts by weight of alkali or alkaline earth metal soap may be replaced with one part of water-dispersible protein to yield a resulting lubricating grease composition characterized by resistance to deformation and bleeding. The particular degree of substitution of soap by the water-dispersible protein will depend in part on the nature of the soap being replaced. Thus, in the case of a sodium base grease, approximately one part by weight of water-dispersible protein will replace one and onehalf parts by weight of soap, while with a calcium base grease, approximately one part by weight of protein may be substituted for two parts by weight of soap. Likewise, the extent of substitution of soap by water-dispersible protein depends on the nature of the soap being replaced. It is generally contemplated, however, that the replacement of soap by protein will not exceed about 30 per cent of the soap content. Thus, in the case of a soda base grease, it has been found that up to 30 per cent of the soap could be replaced with water-dispersible protein. For example, 50 per cent soap in a soda base grease may be replaced with 35 per cent soap and per cent of water-dispersible protein. In the case of a lime base grease, up to per cent of the soap may be replaced with water-dispersible protein. For instance, 50 per cent soap content in a lime base grease may be replaced with 40 per cent of the same soap and 10 per cent of water-dispersible protein.

It will thus be apparent that the characterizing materials of this invention may be used in various amounts extending over a range of from about /2 per cent to about 15 per cent. Preferred amounts for the alkali metal greases, such as soda base grease, are of the order of /2 per cent 'to 6 per cent and for the alkaline earth metal greases, typified by lime base grease, are from about /2 per cent to about 3 per cent by weight of the finished grease.

It has further been discovered that the characterizing water-dispersible proteins described above are most advantageously incorporated in the soap greases prior to or during the saponification stage, as illustrated by the following procedure. A fatty or fatty acid, or mixture thereof, is added to mineral oil in order to provide a blend thereof; if necessary, the materials may be heated in order to thoroughly distribute the fatty material in the mineral oil. The characterizing material of water-soluble or water-dispersible protein is then dissolved or dispersed in water and the resulting water solution is dispersed or emulsified with the blend of fatty material and mineral oil. The resulting dispersion or emulsion is thereafter saponified with a metal hydroxide solution such as caustic soda. Following the latter treatment, water-of solution and of reaction-is evaporated by heatin and stirring the saponified mixture at a temperature above about 220 F., preferably at 260 F. In this evaporation operation, the saponified mixture may also be steam-cooked at temperatures of the order of 250 to 330 F. or fire-cooked at temperatures in the range of 300 to 450 F. The grease is then withdrawn from the vessel in which it was prepared and run into a suitable mold. The grease is allowed to cool, whereupon it solidifies. The solid grease may then be cut into cakes of desired size. By following this preferred procedure, the characterizing water-dispersible protein is incorporated in the grease in an extremely fine dispersed state and the grease is provided with a high order of effectiveness.

The greases of this invention are illustrated by the following typical example:

Example An amount of one part by weight of gelatin (U. S. P. powder) was dispersed with stirring in 50 parts of cold water. Forty-four parts of mineral oil (S. U. V. of seconds at 210 F.) and 30 parts of a fatty material were then added with stirring to the gelatin solution and heated. The fatty material was a mixture of hydrogenated fatty acids (24 parts) obtained by hydrogenation of fish oil fatty acids and hydrogenated fat (6 parts) obtained by hydrogenated fish oil fat. The gelatin-oil-fat solution was heated at about F. and agitated vigorously, whereupon an emulsion was obtained. Caustic soda solution (45 per cent aqueous solution-4V parts) was added to the emulsion at 160 agitation being completed in 10 minutes. The mixture thus obtained was heated and agitated for 3 hours at 280 F. to complete the saponification and was substantially dehydrated (water content 0.1 per cent) thereafter by heating or fire-cookin to a temperature of 330 F. The grease was then allowed to cool, whereupon it solidified. The final product, hereinafter referred to as Grease I, is identified by the following characteristics, all figures being on a dry basis:

Grease I Percent Hydrogenated Fatty Acids 30.3 Hydrogenated Fat 7. 3 Sodium Hydroxide. 5. 7 Mineral Oil 55. 45 Gelatin 1.25

Grease II Percent Hydrogenated Fatty Acids 30. 65 Hydrogenated Fat. 7.4 Sodium Hydroxide 5. 8 Mineral 0il 56.15 Gel None Grease II was prepared by direct saponification of fatty materials and mineral oil with a strong caustic solution in the proportions indicated above and thereafter was substantially dehydrated.

One-inch cubes were cut from 1" thick grease slabs which were representative cross sections, of the grease blocks under test. The cubes were placed on an open tray and the tray was placed on a shelf in a constant temperature electric oven. The cubes were heated at 250 F. for one hour, at 300 F. for one hour, and finally at 350 F. without being removed from the oven. After each of the aforesaid heating periods, the top side of each cube was slightly pressed down with the flat side of a spatula to determine whether there was any deformation or slumping of the cube. In order to pass the test, the sample should show only a slight spreading at the base of the cube and no free oil at the base of the cube after the third test period of 350 F. The results (average of 4 tests) of these tests are tabulated below:

from about 8.5 to about 48 per cent of a fatty material, about 1.5 to about 7.5 per cent of so- Dimensions of Test Cubes 2321323: Per Cent Grease in 1, Decre a.se Oil at Base Before Heating After Heating Area Helght Base 1.00 x 1. 00 1.125" x l. 125 I {Height H 1. 00;; I, 0. sex 27 13 N919- x {88 25 62? 64 38 Considerable.

It will be apparent from the foregoing results that Grease I, which contains gelatin, is greatly superior to Grease II in its resistance to bleeding, as shown by the oil extruded from the latter grease and also in its substantially smaller degree of deformation. The improved greases of this invention are excellent lubricants for locomotive driving journals where high temperatures and pressures are encountered. They also find application as anti-friction bearing greases; for example, ball bearing and roller bearing greases. Other applications for these improved greases will be apparent to those skilled in the art.

The characterizing materials of this invention, as pointed out above, may be used in various amounts in imparting improved properties to greases. In general, the various constituents (on a dry basis) of greases contemplated herein may vary within the following limits:

Per cent Fatty material 8 -48 Alkali 1 /z--.'? Mineral oil 29 /289 /2 Protein It is to be understood that the greases of this invention may also contain other characterizing agents and fillers. For example, they may contain grease anti-oxidants, such as amines, phenols, sulfides, etc.; fillers, such as asbestos, graphite, mica, talc, etc.; and lubricity improving agents, such as free fat, free fatty acids, sulfurized fats, and lead soaps.

It is to be understood, moreover, that the foregoing specific examples are but representative of the greases contemplated herein. The present invention, therefore, is not to be construed as limited thereto but is to be broadly interpreted in the light of the claims appended hereto.

This application is a continuation-in-part of co-pending application Serial Number 602,667, filed June 30, 1945, now U. S. Patent 2,441,720.

We claim:

1. A lubricating grease composition prepared from about 8.5 to about 48 per cent of a fatty material, about 1.5 to about 7.5 per cent of an alkaline material selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, about 0.5 to about 15 per cent of a water-dispersible protein, and the balance, mineral oil.

2. A lubricating grease composition prepared from about 8.5 to about 48 per cent of a fatty material, about 1.5 to about 7.5 per cent of an alkaline material selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, about 0.5 to about 15 per cent of gelatin, and the balance, mineral oil.

3. A lubricating grease composition prepared from about 8.5 to about 48 per cent of a fatty material, about 1.5 to about 7.5 per cent of an alkali metal hydroxide, about 0.5 to about 6 per cent of a water-dispersible protein, and the balance, mineral oil.

4. A lubricating grease composition prepared dium hydroxide, about 0.5 to about 6 per cent of gelatin, and the balance, mineral oil.

5. A soda soap lubricatin grease characterized by resistance to deformation and bleeding, comprising sufficient mineral oil to form said grease, a sodium soap content of from about 10 to about 55 per cent and from about 0.5 to about 15 per cent of a water-dispersible protein.

6. A soda soap lubricating grease characterized by resistance to deformation and bleeding, comprising sufiicient mineral oil to form said grease, a sodium soap content of from about 10 to about 55 per cent and from about 0.5 to about 6 per cent of gelatin.

7. A lubricant selected from the group consisting of alkali metal base greases and alkaline earth metal base greases characterized by resistance to deformation and bleeding, comprising sufficient mineral oil to form a grease, a soap content of from about 10 to about 55 per cent and from about 0.5 to about 15 per cent of a water-dispersible protein.

8. A lubricant selected from the group consisting of alkali metal base greases and alkaline earth metal base greases characterized by resistance to deformation and bleeding, comprising sufiicient mineral oil to form a grease, a soap content of from about 10 to about 55 per cent and from about 0.5 to about 15 per cent of gelatin.

9. A lubricating grease composition characterized by resistance to deformation and bleeding, comprising the reaction products of the following ingredients in the indicated proportions:

Per cent Fatty material 8 -48 Alkali 4- 1 /2 Mineral oil 29 /z89 /g Water-dispersible protein -15 10. A lubricating grease composition characterized by resistance to deformation and bleeding, comprising the reaction products of the following ingredients in the indicated propor- The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 149,996 Cook et al. Apr. 21, 1874 1,410,967 Thompson Mar. 28, 1922 2,108,644 Brunstrum Feb. 15, 1938 2,303,558 Kaufman et al. Dec. 1, 1942 2,346,124 Dew Apr. 4, 1944

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