US2394567A

US2394567A - Lubricating grease composition

Info

Publication number: US2394567A
Application number: US423276A
Authority: US
Inventors: Lorne W Sproule; John C Zimmer
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1941-12-17
Filing date: 1941-12-17
Publication date: 1946-02-12
Anticipated expiration: 1963-02-12
Also published as: GB576470A

Description

Feb. 12, 1946. 1 w SPROULE ET AL 2,394,567

LUBRICATING GREASE COMPOSITION Filed Dec. 17, 1941 Y 2 sheets-sheet 1V O Hoppa O/l..

($8 Y /7 TAN/ FHZIYOI. AND V /aLUM/NUMSOPS f 2 /3 HAAT/Nc.

KLTTl- /6 i Scuw SCRAPER emula 25 26 v 22 l V83 l JJ,

Feb. 12, 1946. I. W. SPROULL- ET AL 2,394,567

I LUBRICATING GREASE COMPOSITION Filed DBC. 17 1941 2 Sheets-Sheet` 2 Hoppa. v l

Ollf TAN/4 w ,f

all. Til/KNER .3 oLUT/ON TANK 1 SCRLW CoNveYoR Pmsted Feb. 1.2,- 194e.

LUBaIcATrNG GnEAsEcoMrosmoN Lome w. spreuk, sansa, ontario, canada, and

John C. Zimmer, Union, N. J., assi Standard Oil Development Company, a corporation of Delaware Application December 17, 1941, Serial No. 423,27

' 14 claims. (c1. l25e- 37) This invention relates to aluminum soap greases highly advantageous in the lubrication of machinery operating under conditionsof local high temperature increases, of irregular and shock load effects, and of frictional forces beyond the iilm strength' of any lubricating oil base material. 'Ihe invention relates more 'particularly to aluminum soap greases adapted for-the lubrication of industrial machinery and the chassis parts of automobiles and crawler type tractors and to an improvedprocess for the preparation of such greases.

Aluminum soap greases have proven to be outstanding lubricants for many types of industrial machinery and especially for the lubrication of automotive and tractor chassis parts. Difficulties, however, in th'e manufacture of aluminum soap greases have greatly hampered their production and utilization. It is well known for example that when aluminum stearate is dispersed in a mineral oil at an elevated temperature and the product cooled, compositions unsuitable as lubricants are obtained. The compositions, for example, vary in texture from being stringy, viscous liquids to solids having a hardfand grainy structure. However, when the so'ap dispersions are carefully cooled in small quantities, a change in structure usually occurs and there is obtained a firm, transparent gel suitable as a lubricant. On the manufacturing scale attempts therefore to cool quickly bulk quantities of aluminum soap-oil blends have resulted in the formation of physically heterogeneous mixtures unsuitable for lubrication purposes. Eilecting the rapid cooling in thin layers isunsatisfactory because often times there are formed soft granular masses unsuitable as grease type lubricants. Thus, on the commercial scale it has been found' necessary to undertake the costly and laborious process of running th'e hot grease composites after blending into shallow pans then allowing the mass 'to cool equipment for reworking and then filtering to effect -the removal of any granular surface iilms and to obtain a relatively homogeneous composition.

pounds thus greatly expedites the manufacturev slowly, then passing the mixture to suitable in structure may occur from being a viscous,

glitty liquid to that of being a suitable gel. This change, however, occurs only when the cooling period is between eight and sixteen hours and when the mass is cooled in small quantities without agitation. However, in the process of cooling large quantities of grease a portion at the outer surface rapidly changes to a gel, while the'rest of the mass hasnot attained the necessary temperature for the transition to suitable gel formation.

Under these processing conditions the outer layers readily break down due to excessive growth of soap particles, and thereafter form thin, liquid 1/4." thick-to temperatures as' low as' 50 F. without granulation or decomposition. The use in this manner of small quantities of phenolic com cf aluminum soap greases; Furthermore, this use of phenolic compounds permits the preparation f grease directly from the cooling devices into larg'e shippingjcontainers, without reworking or filtering.

These advantageous eii'ects of phenolic compounds have been found to occur without the developxnent of any disadvantageous eifects upon any of the desirable lubricating properties of aluminum soap greases. Moreover, these advantageous effects of phenolic compounds in aluminum soap greases'are not disadvantageously affected by the presence of accessory additive materials such as oil thickening agents, anti-corrosive and anti-oxidation agents.

Thus the present invention relates to the preparation of highly stabilized aluminum soap grease compositions containing a phenolic compound as the special additive material for a grease mixture of suitable mineral oil base and an aluminum soap of a saturated fatty acid containing between 10 and 20 carbon atoms in the molecule, such as aluminum stearate. The amount in which the phenolic compound is present in the compositions varies usually between 5% and 30% by weight of the amount of the aluminum soap. The aluminum soap is blended with th'e mineral oil to form a grease of suitable composition in amounts between 3% and 20% but usually between about I 3% and 10% by weight of the oil. Accessory constituents to impart to the composites other desirable characteristics include free, unsaturated fatty acids containing and 20 carbon atoms in the molecule and their aluminum soaps, naphththenic acids and their aluminum soaps; and oil thickening agents, such as latex or polybutene.

Phenolic compounds in general havebeen found' f to be effective as additives to grease compositions according to the present invention.v l{Initl'ie `choice oi a phenolic compound as a suitable blending agent for a particular grease composition, selection is made largely on the *basic of its vapor pressure and its relative effects upon oil solubility and misclbility with other-@'constituents as regards effecting the lowering of-f the transition temperature. It is also important to select the phenolic compound on the basis of its efiect in physically stabilizing the finished grease. Thus it has been found that the mono nuclear phenols are in general slightly more eiective than the poly nuclear phenolic compounds, and that for vapor 'pressure andsolubility characteristics it until all of the soap and phenolic compounds are thoroughly incorporated to form a smooth homogeneous mass. The mass after heating is then rapidly cooled by passing through cooling equipment to a temperature of about 90 F. The cooling may be effected by passing the material into -shallow pans and then returning the cool grease to mixing equipment wherein the mixture is allowed to settle to about the transition tempera- -,ture.- Onv the otherlhand, the material may be plied the further quantities of oil as are required to prepare the. finished grease. The mixture is then passed through a coil heater at a temperature of about 300 F. and then allowed is preferable to employ the alkylated phenolic v compounds. In regard to the physical stabilization of the grease products certain of the substituted phenols such 'as the amino phenols are preferable. However, substitutedphenols such as the halogenated and sulfur-bearing derivative are eflective.y Particularly effective phenols are the alkylated compounds having one or more alkyl side chains. Of the various phenolic compounds effective for purposes of this invention particular mention may be made of naturally occurring phenols, derived especially from petroleum and coal tar, the cresols, the amyl phenols, dihydric phenols, a-naphthol and -naphthol.

kThe effect of the vphenolic. compounds appears to be connected pre-eminently with the compounding and cooling steps in the preparation of the greases. It appears that phenolic compounds function in the aluminum soap-mineral oil blends to permit rapid cooling without crystallization of the aluminum soaps. Thus, the phenolicrv compounds permit the mixture after to settle to permit the separation of any occluded gases before passing through a helical screw type cooler. By this means a grease can be satisfactorily prepared in large quantities on a continuous basis, and the product directly passed to the shipping containers from the cooling equipment.

`An illustration of the methodr of preparing the grease involving the use of the usual type kettle for heatingand blending the constituents is compounding to be agitated during cooling and the transition in structure to occur at the' lower temperatures than hithertofore in vessels of even 400 lbs. capacity. l 1

In preparing the lgrease compositions of this invention, the oil employed is preferably derived from a naphthenic base crude, as for example oils of the Coastal type. The viscosity of the oil is usually above about 85 seconds Saybolt at 210 F., and preferably from to 200 seconds Saybolt at 210 F. The aluminum soap and the phenolic compounds are added to the oil at a temperature between about 130 F. and 150 F. The heating may be carried out in a coil type heater or in the usual type kettle. A suitable heating kettle is furnished with mechanical means .of agitation, usually paddles having at the outer sweeps close fitting scraper adjustments to pass over its inner surface in order to insure good heat transfer and to obviate the development' of surface iilms. Usually the aluminum soap and the phenolic compounds are blended with about 10% to 20% of the total quantity of the oil to be used and the mixtureworkedinto a thick non-lumpy paste. This paste is then stirred into the balance of the oil, and heated to a temperature of between 280 F. and 300 F. and held at that temperature ing uid in the Jacket '2L ternally with paddles Il having scraper termi nals I2 which can be finely adjusted to work upon the entire surface of the kettle. The motion of the paddles in. the kettle insuresvery complete and thorough agitation within the kettle. The jacket portion i3 of the kettle I0 is adapted for the passing in through line I4 and the passing out through line' I5 of steam eitherl under normal or superatmospheric' pressure as temperatures within the kettle I0 require. Under the conditions of such means of agitation and of a temperature between about 280 F. and about 300 F., suflcient oil of suitable character as a mineral oi1 base for the preparation of the grease composition is supplied from storage tank I6 to the kettle I0 through line I1 and admixed with the aluminum .soap and phenolic compoundsv supplied through opening I8 to make a smooth thick paste. Further quantities of oil to make the grease of desired consistency are then `supplied through line I1 and the mass agitated until a smooth homogeneous composition is obtained.

When the mass in the kettle has become smooth is usually operated countercurrently to the direc-f tion of the flowfof the grease from line I8 and countercurrently to the direction of the cool- The scraper screw is operated by the motor 25 through' gears 26 and transmission 21. The cooled grease -Vpasses from the chiller through line 28.

In batch operation the cooled grease is recycled through line 28 to the kettle III. By such recycling the entire quantity grease composition is brought to about the transition temperature at Vfree owing slurry composition.

about the same time. When this temperature within the mass is reached, agitation within the kettle is discontinued and the mass is allowed to settle and to cool further until the transition in structure has been satisfactorily effected. The gel composition is then removed from the kettle through a T 29 on linei9 and passed to shipping containers,

In continuous operation it is'usual to employ a series of kettles similarly equipped to that designated by the numeral I and to pass the hot mixture to the chiller in a relatively continuous stream from the various kettles through the T 30 on line I9. In this manner of operation the cooling effected in the chiller is more complete than that in batch operation, namely the cooling in the chiller is effected to about the transition temperature. tion is passed directly through a T 3| on line 28 to the shipping containers wherein settling and further cooling to atmospheric temperature are effected.

Figure 2 indicates a second processing method by which the grease can be prepared. According to this process the oil is passed from a supply tank 40 through lines 4| and 42 into a countercurrent rapid batch mixer 43. To the mixer 43 is also added through the hopper 44 the required amounts of aluminum soap and phenolic compounds. The oil, the aluminum soaps and the phenol are added in quantities so as to form a The slurry is then passed through line 45 to an orifice mixer 46, to which is also supplied through line 41 the further quantities of oil from the supply 40, to form the grease of the desired composition. The mixture is then passed through line 48 and pump 48 to the coil heater 50 wherein it is heated to the necessary compounding temperature which is usually about 300 F. by means of steam passed through lines 5| and 52. r.ihe hot mixture then passes through line 63 to a surge tank 54 wherein any occluded air or gas formed during the heating process is permitted to escape through the vent pipe 55. To-the surge tank mayalso be supplied through line 5B an oil thickening agent, such as polybutene or latex, from the tank 61. The grease mixture is removed from the surge tank 54 through the line 53 and passed to the screw conveyor type chiller 69, which is cooled by the water Jacket 60. The grease is cooled usually therein to a temperature ofabout 90-100" F. and then passed directly through pipe 6| to the shipping containers 62.

'I'he following example is presented to illustrate the preparation and various characteristics of suitable greases 4prepared according to this invention:

A grease of the `following composition was prepared:

, I Per cent Aluminum stearate 6. 50 Tert.octy1 phenol 0. 75 Lubricating oil of 200 S. U. vis/210 F 14. 00 Polybutene 0. Lubricating oil of 70 S. U. via/210 F..-- 78. 50

The lubricating oil of 200 S. U. viS./210 F. 'and the aluminum stearate were charged to a heating kettle as illustrated in Figure 1, and the mixture agitated by means of therpaddles for about 1 5 minutes. Then the lubricating oil of 70 S. U. vis/210 F. preheated to about 130 F. was added and agitation continued. The tert.octyl phenol and polybutene were then "added and the temperature of the mixture raised to about. 280 F.

The cooled grease in such opera- At this point'the heating was discontinued and the mixture cooled by passing cold water through the kettle jacket. The grease was thus cooled with agitation to about 95 F., then agitation discontinued and the mass allowed to stand for 21/2' hours. The grease after this period ot standing was found to be of a. smooth plastic gel nature.' The grease so prepared had an unworked penetration at 90 F. of 255, and a. worked penetration at 90 F. of 338.

Ihis'grease was then heated to 310 F. and held at that temperature for minutes. 'I'he grease'was cooled to 305 F.' by circulating cold water through the kettle jacket and then pumped into the cooler supplied with water at '12 F. The vgrease after one pass through the cooler (temperature o! exit water 88 F.) was passed into various containers at different temperatures and allowed to cool therein to atmospheric temperature. The following table presents the results:

. Worked penetrations 24 hours Amount and capa- Temperalater' city of container ture, F

. Outer layers Core l The second value was obtained twelve days later than the ilrst 85 value.

Comparison of these data demonstrates that y continued. The gre'ase at 300 F. was circulated over a prolonged `period through the cooler into kettle with the following results:

Temperature, F. at end of cooler Temperature Time in keine, F.

2 hours 35 mins 113 130 The grease cooled to 113 F. was then passed at the rate of 16 lbs/minute .to illl a 400 lb. barrel. After standing for 20 hours at atmospheric` conditions the core was found to have a temperature vo! F. and the following penetration data were obtained.

Representative sample Outer on" of same malayers terialoooled in 1 pound can Unworkcd penetration 261 310 Worked penetration 356 400+ 336 Comparison of these data demonstrates the efrect of the rate of cooling inthe presence'o! tert. octy1 phenol of a1uminumstearate greases `the following penetration values:

widely different size containers, and that the" penetration values of the outer layers of cooled bulk masses approximate that of the'product cooled in smaller size vessels. When a sample of the grease composition f Example I was vpassed directly from the kettle at 300 F. to ll a 400 lb. drum and the mass allowed to stand for j10 days, the product was a semi-fluid mass wholly unsuitable as a grease-type lubricant. On the other handV when a similar batch of grease was grease product, having nov grain formation, and

Rim Center nnworked 261 zes WMM* 353 35o Thus, it has been shown that satisfactory aiuminum soap greases can be prepared in the presence of phenolic compounds from blends of theA soaps of the saturated fatty acids containing between `10 and 20 carbon atoms in the molecule, such as aluminum stearate, in viscous oils by rapidly cooling from the compounding temperatures to almost normal temperatures. This rapidcooling to atmospheric temperatures permits the grease products to be packaged directly into bulk shippingcontainers. The discovery of this eiect of phenolic compounds obviates the timeand labor-consuming and the costly prior art process of preparing aluminum soap greases by'pan-cooling and subsequent reworking, and also avoids `the consistency loss based uponfthe quantity oi' aluminum soap employed. It would seem that the action of thephenolic compounds has basis in preventing the recrystallization of the aluminum soaps at temperatures below about 140 F., that is, an effect in grease compositions similar to that of pour depressants in waxy mineral oils inhibiting the crystallization of the wax content. Thus, the use of phenolic compounds permits departure from the prior art procedure of being able to cool the grease to minimum temperatures of about 140 F. and then having to continue the `preparation oi the grease by pan-cooling, by allowing the hot grease mixture to be cooled with agitation to temperatures well below 140 F. 1n thisvmanner greases having a worked penetration at 77 F. of between about'50 and about 360 or higher may be easily and readily prepared.

The advantages of the use oi phenolic com--l pounds in the preparation of aluminum soap greases are attained without loss of any of the desirable properties of aluminum soap-mineral oil grease composites. grease products containing the phenolic comthe various constituents insuring good lubricatis exerted lan added stabilizing effect. In other words. it appears that a minor portion of the l composition exists as a colloidal dispersion of the soap compounds in a relatively stable emulsion of a major portion of a colloidal dispersion of other soap compounds in the mineral oil of suitable consistency. This relationship, as indicated by tests, such as penetration, adhesiveness ,tov metal surfaces, internal cohesion, melting point, etc., .is considered important in order that there be formed on the bearing surfaces a satisfactory adhesive lubricating iilm while the colloidal phase functions to offer substantial resist- It would seem that in the' cooled in the kettle to 95 F. and then passed into Va 400 lb. drum, the product was a satisfactory ance toward heat conduction from the surface film into the mass thereby minimizing the eflect v of friction, speed and'load during service upon the bulk of the grease composition.

. The present invention is not to be limited by any theory of manufacture or to any particular` type of aluminum soaps, but only to thev follow ing claims or their equivalent.

What is claimedis: v

1. Process for preparing##aluminum l soap greases which comprises thoroughly mixing at a temperature from about 280 F. up to about 300" F. a viscous mineral lubricating oil,`abo utf3 to of aluminum stearate and from aboutv 15.40.2595, to 1.5%,of a phenolic compound,VV rapidly greases which comprises thoroughly mixing at a cooling the heated mixture to a temperature be-V low 140 F. and allowing the mass to stand. Y I

2. Process according to claim 1 in which the phenolic compound is a mono-nuclear phenol.

phenolic compound is an alkyl phenol having between 3 and 8 carbon atoms in the alkyl grouping.

4. Process according to claim 1 in which the phenolic compound is tert.octyl phenol.

thorough mixing at an elevated temperature is veffected by passing the ingredients rst through an orifice mixer and then through a coil heater. 6. Process for preparing aluminum soap temperature from about 280 F. up to about 300 F. a viscous mineral lubricating oil, about 3 to 10% of aluminum stearate and from 0.25% to f 1.5% of amano-nuclear phenolic compound, rap- 36 idly cooling the heated mixture to a temperature below about 140 F., in a owing stream and allowing the cooled mass tostand. Y

y ,7. Process for preparing aluminum soap grease according to claim 6V in which the rapid 40 cooling'is eiected-by passing through a helical screw scraper type cooling equipment in which the flow of the heated mixture is in the opposite direction to that of the motion of the screw and countercurrent to the ow of cooling Jacket.

8. Process according to claim 6 in which the mono-nuclear phenolic compound is an alkylated mono-nuclear phenol. 0

9. Process for preparingsemi-Huid aluminum soap greases for the lubrication of chassis parts of crawler-type tractors which comprises thoroughly mixing at a temperature from about 280 F. up to about 300 F. a viscous mineral lubricat-V ing'oil of betw( en 150-200 seconds Saybolt at 210 F., about i, to 10% of aluminum stearate pounds, the advantageous relationship between 60 ing fquality is attained and that in addition there and from 0.25% to 1.5% of an' alkylated mononuclear phenolic compound, rapidly cooling theheated mixture in a iiowing stream to a temperature below about F., and then allowing the mixture to stand.

10. A lubricating grease for the chassis parts of crawler-type tractors-comprising a ,mineralV lubricating oil having `a viscosity of from about to 200 seconds Saybolt at 210 F., about 5% aluminum stearate, 0.75% of an alkylated'mononuclear phenol, about 0.1% polybutene, the whole being worked intoa homogeneous mass laizag/ing a worked :penetration at 77 F. oi' about 11. A lubricatingl grease according to claim'lO in which the alkylatedmono-nuclear phenol is tert.octyl phenol. Y

12. Process forl preparing an aluminumv soap 75 grease which comprises thoroughly mixing at an 3. Process according to claim 1 in which the" 5. Process according to claimv 1 in which the.

the fluid m the oezaturc sufcent to eect substantr lof; blending a viscous mineral lubricating oil with at least 3% of an aluminum soap of a saturated fatty acid containing at least 13. Process according to claim 12 ln which the pheaolo compound ls an alkyl phenol ha from 3 to 8 carbon atoms in the alkyl grouping.

l. Process according to claim 12 in which'the carbon atoms per molecule and from about 5 phenolic compound is tem-octyl phenol.

to 3.5% of phenolic compound, and rapidly cooling the entire mass in bulk without agitation to a temperature below wir F.

LORNE W. SPR' l JOM C. ZIIMDIIER.