US1973537A - Solid lubricant - Google Patents

Description

will-immediately melt to flow to the part to be By this invention, wealso produce a densely and a low watercontentanii having a, melting.

Patented Sept. l1, 1934 UNITED STA T-Es PATENT OFFICE soup ppnmcm I Charles A. Miller and Charles B. .Kams,-- Frank lm, Pa., assig'nors, by

I Valvoline' Oil Company,

. corporation of New Jersey No Drawing. Application-Deer I a Serial No. 152,055-

is Claims. This invention relates to improvements in solid lubricants and more particularly to that" class of hard lubricants designed to be used in cake form ior lubricating locomotive driving 1 '15 journals and other bearings of heavy members working at high speed.

' One of the objects of this invention is produce a lubricating grease 01' high oil and low water content with a melting" point of over :10 400 F. which will have increased hardness and a dense consistencyto' enable it to be' formed in blocks or cakes by pressing or molding and to.

'- lubricatedwh'ile" the mass of the grease other than the contact portion will remain .in .an unmeltedstate.

-'Another object ofv the invention'is to pro- -30 duce a solid lubricating. grease which, whenmelted to a fluid state, upon .cooling, will re turn to its original densely solid structural con- .dition without. impairment of its lubricating qualities;

solid grease havinga fibrous structure substantially 'free from moisture and having a melting point of 400" F. or over. Another object of the invention is to enable the production of a lubricating grease having,

substantially the hardnessand consistency of I vhardsoap, comprising a relatively high percentage of mineral oil, a relatively low percent p e r soap stock in the form of stearate point of 400? F' or ver.v I n l r In carrying" out our invention, we,.. preferably.- provide ior use" in relatively. warm; climates 'formula' substantially ,as iollows:.;

,being applied at approximately 200 is expelled from .the 'mass.- 'erably turned-.oifjust prior to the addition of the as a'ioresaid, water-in the form of mesne; 1 assignments, ito

C nc nnat 0 1 mm Forf colder jelirnates, we preferably use a grease formulawith a higher oil content, as follows:' e

i a -Percent ,Heavy mineral oil cylinder stock (para fine base) 54. 12 Stearic. acid 37. 64 Granular caustic soda 6.59- Water 1. 64 5 In making ourimproved grease, we utilize an open-top, steam-jacketed kettle of largev enoughcapacity to-prevent the mass from overflowing the kettle, and we preferably first intro-H duce the stearic acid,-then the oil, heated to permit-convenient handling, is then run into the kettle, after which sufiicient heatis applied to melt the stearic acid, such heat;preferab1y .75

F. during this period. Agitation is begun so soon as the stearic acid cakes are'partially melted to assist in the melting, and when the stearic acid is completely melted, the mixing is substantially '80 completed "at the same time. The alkali, preferably comprising as indicated in the above formula, granular caustic soda, which has been .previously prepared by heating with a small quantity of .water to bring it'into substantially 8 5 paste form, is now added to the stearic acid andoil, agitation being continued during the introduction of this alkaline paste.

paste, a -very 'violent reaction takes'pla'ce with '00 a boiling and ,risingof vapors, and an autoguenousgeneration' of heat, the temperature of the mass being raised'to'approximately 230 F. Duringrthis reaction, water in the form of'steam The heat is pref alkaline paste, the agitation, however, being continued duringtheareaction of saponific'ationfi The; mass of: material greatly increases in bulk i and risestoward the top of the kettle; givingoff,

steam. So Soonas the reaction is-completa'the bulkof the material begins to decrease and descend in the a k ettl e and to pull ,away from the sides. At this time, {the material is a relatively dry, spongy-,or' gummy-mass. Heat with agitation is now an"- plied, a temperature of approximately 350 F. being preferred, for'the purpose of softening-the compound to bring it into a smooth-doughy form 0!. hqmqgeneous mass in which'form itllO Shortly; afterwthe addition of the alkaline may be caused to flow and be drawn from the kettle. Agitation is preferably continued throughout this period until the compound is removed from the kettle.

The finished product after cooling, comprises a solid, relativelyjhard and compact grease of dense and fibrous structure, the particles having.

a very high degree of coherence, and the density and stiffness being substantially equal to the average hard soap. This dense structure is desirable for the reasons hereinabove specified and we find that there is no tendency in the;

mass, of segregation or the formation of oil pockets frequently found in lubricating greases, but on the contrary, a homogeneous soap-like mass is produced. Furthermore, the use of stearic acid as the saponifying base, enables the introduction of an increased percentage of cylinder stock to be added to the lubricant. than would be possible, forexample,withother fatty oils. We "have found that such a compound has a melting point of approximately 450 F. An average analysis represented by the examination of three samples of the above-mentioned lubricant gives the following:-

. Percent Sodium stearate 46. 97 Free alkali (NaOH) 0.44 Heavy mineral cylinder stock (parafllne base) 51. '79 Water and undetermined matter 0.80

, We preferably use refined, well-pressed stearic acid in order to produce a hard dense grease of a higher melting point than can otherwise be obtainedand also to enable the incorporation in such a hard grease of an-increased quantity of mineral oil as hereinabove specified.

We find that this grease has greatly increased efliciency in use in the bearings of locomotive driving" journals and the. like and particularly in ,the journal boxes under spring pressure; furthermore that under ordinary-conditions, this grease gives perfect lubrication and under extraordinary conditions, as for example, "when therev issuch amechanical irregularity in the mechanism lubricated as to cause excessive heat, the outer surface-of the cake of lubricating grease, will be meltedjandflow to the part required while the mass of the grease, due to its poorheat-conductivity and cohesiveness, will remain in normal unmelted condition, thus resulting in a great economy of grease and preventing too rapid discharge of the grease and the subsequent failure of lubrication ,by the particular charge of grease. Furthermore, we have ascertained that when our compound is used under conditions of high. temperature, as for example, in the bearings of locomotive driving journals that. are located adjacent togthe fire box or ash pan of theboiler, thislubricantwill not, in any way, be impaired by, the action of excessive heat -at these. points and due to the high oil content of this grease, .a relatively smaller quantity thereof will be required in any given period of It. will ,be understood also that the physical characteristicsof the grease including the fland water 1%.

with free alkali of less than one percent (1%) and heating'the product to complete the reaction. 3 2.=The process'of manufacturing solid lubricants which comprises mixing a viscous hydrocarbon oil with stearic acid at the melting temperature of the latter, reacting with sodium hydrate in sufficient quantity to saponify the acid with free alkali of less than one percent (1%) previously prepared in ,paste form by heating granular caustic soda with a small quantity of water, and heating the product to complete the 9 reaction. 3. A solid lubricant consisting of, a paraflin base cylinder stock, approximately 52%, sodium stearate approximately 46.5%, free alkali 0.5% 0

4. A solid lubricant having a fibrous structure and consisting of a parafllne base cylinder stock 52%, a higher fatty acid soap 46.5%, free alkali 0.5% and water 1%.

5. A solid boiled lubricating grease principally composed of a dehydrated mixture of a heavy viscous hydro-carbon oil and a sodium stearate soap freed from glycerol, said grease having approximately the hardness and consistency of the average hard soap.

' 6. A solid boiled lubricating grease principally composed of a-dehydrated mixture of a heavy viscous hydro-carbon mineral oil and a sodium stearate soap, said two ingredients being present in approximately equal proportions, and said grease havingapproximatelythe hardness of the average hard soap.

7. A solid lubricant principally composed of a dehydrated mixture of heavy viscous hydro-carbon oil and sodium stearate soap prepared from stearic acid and caustic soda, said two ingredients being present in approximately equal proportions and comprising substantially the entire grease with the exception of water and free alkali in quantities of less than one percent (1%) each, said grease having approximately the hard-- ness and consistency of the average hard soap and having a melting point of the order of 400 F.

8. A solid boiled lubricating grease principally composed of a dehydrated mixture of cylinder stock and sodium stearate soap freed from gylcerol, said cylinder stock and soap being present in approximately equal proportions, and said grease having approximately the hardness and consistency of the average hard soap, and also having a fibrous structure.

- 9. A solid boiled lubricating grease principally composed of a dehydrated mixture of cylinder stock and the products of reaction under heat of stearic acid with caustic soda in a quantity sumcient to neutralize the acid with an excess of alkali of not more than one percent (1%), said grease having approximately the hardness and consistency of the average hard soap.

10. A solid boiled lubricating grease principally composed of cylinder stock and the product of reaction under heat of well-pressed stearic acid with caustic soda in paste form in a quantity suflicient to neutralize the acid with an excess 13. A solid substantially dehydrated lubricat-.

of alkali of not more than onepercent (1%), said grease having approximately the hardness and consistency of the average hard soap.

11. A solid boiled lubricating grease having a soap content comprising sodium stearate free from glycerol approximately 47%, cylinder stock approximately 52% with less than 1% of water, said grease having a hardness and consistency of approximately the average hard soap. j

12. A solid boiled lubricating grease produced fromapproximately the following materials:-

, Percent Heavy mineral cylinder stock (parafline base) 52. 18 Stearic acid 39. 23 Granular caustic soda 6. 3'7 Water l. 72

and having approximately the following average analysis:

Percent Sodium stearate 46.97 Free alkali (NaOH) 0. 44 Heavy mineral cylinder stock (parafline base) 51. 79 Water and undetermined matter 0. 80

approximately the consistency of hard soap and having a melting point above 400.

15. A solid substantially dehydrated lubricating grease comprising a paraffine base cylinder stock and sodium stearate soap freed from glycerol, said two ingredients being present in approximately equal proportions and comprising substantially the entire grease.

CHARLES A. MR. CHARLES B. KARNS.