US2487378A

US2487378A - Lubricant

Info

Publication number: US2487378A
Application number: US21757A
Authority: US
Inventors: Theodore G Roehner; George W Murray
Original assignee: Socony Vacuum Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1948-04-17
Filing date: 1948-04-17
Publication date: 1949-11-08
Anticipated expiration: 1966-11-08

Description

Patented Nov. 8, 1949 UNITED. STATES AT ENT OFFICE W. Murray, Plcasantville, N.Y., 'Socony-Vacuum Oil Company,

assignors .to Incorporated,

.a corporation .of t New York No Drawing. Application April 17, 1948, Serial No. 21,757

10 Claims.

I"his-invention relates to lubricants andgmore particularly, is'concerned with lubricants characterized by ahigh order of effectiveness under severe operating conditions.

It *iswell 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. with=a "grease, 'it is essential to-provide a grease which willsubstantially retain its character under the-foregoing conditions. Failure to dose results in-high consumption ofthe lubricant and frequent servicing. In general, available greases sufier'-from a marked tendencyto change in character whenuse'd-over '-a wide range of temperature. *For-example, the consistency-of a conventional grease is prone-to'change .overa wide range of temperature. Certain soda basegreases, forexample, have a'pronounced and undesirable property of changing from a short to a long fibre structure with temperature change. Some conventionalgreases are also characterized .by excessive softeningwhen exposed to elevatedtemperatures, thereby'being extrudedtoo rapidly from .the .area ..being lubricated to .provide aidcient lubrication. In addition, some greases tend to lose their Oil content "when used at elevated temperatures and pressures. This condition is general-lymeferredto' in the art-as bleeding.

In accordance with the present invention, there has now beendiscovered a grease which is characterizedby ahigh order of effectiveness under severe operating conditions and -which issubstantially-iree from the shortcomingsdiscussed above. The greases contemplated herein contain,

as-a characterizing or reinforcing agent, a smallamount of a water-dispersible or. oil-insoluble and water-soluble resinous condensation product of:an aromatic phenolic .compoundand an aldehyde. Typical "of the materials contemplated as reinforcing'agents'inthe greases of this inventiomzare the water-dispersible phenol-formaldehyde typeresins. These resinous-.materials rep-. resent .the-productsmf initial condensation -betvmeemphenol and -formaldehyde, conventionally referred to as the A stage of condensation; The-water-dispersible-; product so obtained consists substantially .of ;:linear polymers of: phenol and.-.-formaldehyde ,prior to: the formation-oi ap In'lubricating machine parts.

preciable cross linking between the molecules,

which results in an undesirable decrease in wa-' the alkali metal. and alkaline earthmetal base greases; that is, those greasecompositions consisting of mineraloil inadmixture with alkali metal or ;alkaline-;earthmetal soaps of fatty acids or with a sufficient proportion of such soaps pres ent to:give.zthecharacteristics usually recognized as attributable to alkali :and alkaline earth metal base greases. The soap content of these greases is generally between aboutlO and about '55 per cent by weight on the basis of the final product. They-are generallyzprepared by heating a fat or a fatty .acid, ora mixture thereof, with a'mineral oil and thereafter'heating the resultant mixture withz-the-desired metal hydroxide at elevated temperatures toobtain 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 donot maintain their shape at elevated temperatures and fire-cookedgreases are typified by bleeding under such conditions.

The mineral oil constituent ofthe greases contemplated herein may vary considerably in character andincludesresidual or distilled oils. vPreference is accorded,v however, to oils having a viscosity .(S. U. V.) of 100 to 250 seconds at 210 F.

Similarly, the fats andfatty 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 hydroxide and calcium hydroxide are preferred in'view of cost considerations and a greaterdemand byindustry for soda and lime base greases, other. metal hydroxides may be used in the present greases, preferably where the soap con: stituent of .the grease is prepared by direct saponification in aqueous phase. Accordingly.

vention, that from one to two parts by weight of alkali or alkaline earth metal soap may be replaced with one part of Water-dispersible phenolformaldehyde resin to yield a resulting lubricating grease composition characterized by resistance to deformation and bleeding. The particular degree of substitution of soap by the waterdispersible phenol-formaldehyde resin will depend in part on the nature of the soap being replaced. Thus, in the case of sodium base grease, approximately one part by weight of water-dispersible phenol-formaldehyde resin will replace one and one-half parts by weight of soap, while with a calcium base grease, approximately one part by weight of phenol-formaldehyde resin may be substituted for two parts by weight of soap. Likewise, the extent of substitution of soap by water-dispersible phenol-formaldehyde resin depends on the nature of the soap being replaced. It is generally contemplated, however, that the replacement of soap by phenol-formaldehyde resin 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 phenol-formaldehyde resin. For example, 50 per cent soap in a soda base grease may be replaced with 35 per cent soap and 15 per cent of waterdispersible phenol-formaidehyde resin. In the case of a lime base grease, up to 20 per cent of the soap may be replaced with Water-dispersible phenol-formaldehyde resin. 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-dlspersible phenol-formaldehyde resin.

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 per cent to about 15 per cent. Preferred amounts for the alkali metal greases, such as soda base grease, are of the order of per cent to 6 per cent and for the alkaline earth metal greases, typified by lime base grease, are from about per cent to about per cent by weight of the finished grease.

It has further been discovered that the characterizing water-dispersibl phenol-formaldehyde resins described above are most advantageously incorporated in the soap greases prior to or during the saponification stage, as illustrated by the following procedure. A fat 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 phenol-formaldehyde resin 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, waterof solution and of reaction-is evaporated by heating 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 firecooked 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 phenol-formaldehyde resin 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 waterdispersible phenol-formaldehyde resin, representing a late A stage of condensation of phenol and formaldehyde and containing 73 per cent solids, was dispersed with stirring in 37 parts of mineral oil (S. U. V. of seconds at 210 F.) and 25 parts of fatty material were then added with stirring to the phenol-formaldehyde solution and heated. The fatty material was a mixture of hydrogenated fatty acids (20 parts) obtained by hydrogenation of fish oil fatty acids and hydrogenated fat (5 parts) obtained by hydrogenated fish oil fat. The phenol-formaldehyde-oil-fat solution was heated at about F. and agitated vigorously, whereupon an emulsion was obtained. Caustic soda solution (45 per cent aqueous solution, 4 parts) was added to the emulsion at 160 F., agitation being completed in ten minutes. The mixture thus obtained was heated and agitated for 3 hours at 280 F. to complete the saponification and was substantially dehydratedlwater content0.1 per cent) thereafter by heating or fire-cooking 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 Per Cent Hydrogenated Fatty Acids 3 Hydrogenated Fat- Sodium Hydroxide. Mineral Oil PhenolFormaldehydc Resin Grease II Per Cent Hydrogenated Fatty Acids 30. 65 Hydrogenated Fat 7. 4 Sodium Hydroxide. 5. 8 Mineral Oil 56.15 Phenol-Formaldehyde Resin None Grease II was prepared by direct saponifica tion of fatty materials and mineral oil with astrong 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' traynan'd the' tray was placed on..a shelf in .a constant temperature electric oven: The'cubes were-"heatedfat 250E5'f0hone hour, at 300 F. for one hour, andfinallyat 350 F. withoufibeingremovedrfronrtheioven. After each of, the aforesaid heating periods, the top side of-each cube was slightly pressed downwith the flati side of aspa'tula to determine.. whether there was any deformation or slumping of the cube. In o'rder't'o pass thetes-t, 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:

Dimensions of Test Cubes Per Cent Per Cent Grease I-nmease Decrease Oil at Base Base in Height Before Heating After Heating Area I L001: 2? 27 13 None. 1.00 x 1.00 1. x

1. 625 64 38 Considerable.

It will be apparent from the foregoing results that Grease I, which contains phenol-formaldehyde resin, is greatly superior to Grease II in its resistance to bleeding, as shown by th 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 bearin-g 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 /2-48 Alkali 1 /2- 7 /2 Mineral oil 29 -89 Phenol-formaldehyde resin /215 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 2,241,720.

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 phenol-formaldehyde resin, and the balance, mineral oil.

4. A lubricating grease composition prepared from mineral oil, about 8.5 to about 48 per cent of a fatty material, about 1.5 to about 7.5 per cent of sodium hydroxide, and about 0.5 to about 6 per cent of an A stage condensation product of phenol and formaldehyde.

5. 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 15 per cent of a water-dispersible phenol-formaldehyde resin.

6. A soda soap lubricating 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 6 per cent of an A stage condensation product of phenol and formaldehyde.

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 phenol-formaldehyde resin.

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 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 an A stage condensation product of phenol and formaldehyde.

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 /2-48 Alkali 1 b- 7 Mineral oil 29 -89 Water-dispersible phenol-formalde hyde resin /g-15 10. A lubricating grease composition characterized by resistance to deformation and bleed- 111g," comprislng the lFeacti-on. products Of the i followmg mgredlents 1n the mdlcated proport The following references are of record in the Per cent file Of patent: Hy g na d fatty acids 30.3 5 UNITED STATES PATENTS Hydrogenated fat 7.3 Sodium hydroxide 5.7 Number P Date Mineral Oil 5555 2,104,408 W1ezev1ch Jan. 4, 1938 Water dispersible phenol formaldehyde ,108,644 Brunstrum Feb. 15, 1938 resin 05 10 2,303,553 Kaufman et a1. D80. 1, 1942'.

THEODORE G. ROEHNER. GEORGE W. MURRAY.