US2828261A

US2828261A - Inorganic gel-thickened lubricant having good temperature susceptibility and dynamicwater stability characteristics

Info

Publication number: US2828261A
Application number: US409007A
Authority: US
Inventors: Ernest C Milberger; Veatch Franklin
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1954-02-08
Filing date: 1954-02-08
Publication date: 1958-03-25
Anticipated expiration: 1975-03-25

Description

United States Patent INORGANIC GEL-THICKENED LUBRICANT HAV- ING GOOD TEMPERATURE SUSCEPTIBILITY AND DYNAMIC WATER STABILITY CHARAC- TERISTICS Ernest C. Milberger, Maple Heights, and Franklin "catch,

Lyndhurst, Ohio, assiguors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application February 8, 1954 Serial No. 409,007 4 7 Claims. (Cl. 252-28) This invention relates to an aerogel-thickened lubricant of good temperature susceptibility and water resistance characteristics.

Mineral lubricating oils thickened with a calcium or sodium soap are the most commonly used lubricants. The so-called soda base greases have relatively good stability at reasonably elevated temperatures but deteriorate readily in the presence of water, presumably due to the high solubility of the soda base soap in water. Calcium soap greases have better resistance to water but tend to lose their consistency or thin out at elevated temperatures. Both types of soap base greases breakdown at temperatures of the order of 300 to 400 F. and this breakdown is accompanied by an irreversible change in the grease structure so that on cooling the grease is found to have lost its greaselike characteristics. The aerogel greases usually are far superior to the soap base greases in stability at high temperatures as the following table shows:

Y Complete separation of oil plus soap.

Unchanged except somewhat thinner.

Unchanged, upon stirring, breaks down into a heavy liquid.

Unchanged Silica aerogel; l

Do do However after heating at high temperatures some aerogel greases tend to thin out upon stirring and this is undesirable in field applications where a grease is agitated or worked while subject to a high temperature. Aerogel greases also reveal an unsatisfactory dynamic water resistance and this again is unsatisfactory in field applications where the grease is agitated or worked in the presence of water. The grease may emulsify with water to the point of inversion to an oil-in-water emulsion, at which point the grease characteristics are lost. r

In accordance with the invention water-insoluble oilmiscible or -dispersible polyalkylene glycol ethers characterized by a. viscosity at 100 F. within the range of 285 to 1145 SSU are employed in conjunction with an alkylol or amino imidazoline in thickened lubricant compositions comprising a lubricating oil thickened with a nonabrasive inorganic thickening or filling agent and particularly finely divided silica, a silica aerogelbeing illus- 2,828,261 Patented Mar. 25, 1958 ICC trative. The thickened lubricants so prepared have ex cellent temperature susceptibility properties and excellent dynamic water resistance, attributable to the presence of the alkylol or amino imidazoline and the polyalkylene glycol ether.

The glycol ethers are characterized by the following general formula:

where n is an integer having the value of one or more, preferably one, two or three, x is an integer taken in suificient number to produce an ether having the prescribed viscosity, R and R are hydrogen or lower alkyl groups, and R is a lower alkyl group. When-n is one, the oxyalkylene chain has at least a small proportion of oxyalkylene units of at least three carbon atoms, so that at least one of R and R is a lower alkyl group, preferably methyl. The lower alkyl group can have from one to about five carbon atoms, such as methyl, ethyl, propyl, or amyl and can have either a straight or branched chain. Preferably, one of R and R is hydrogen and one is a methyl group, and R can be methyl, ethyl, or isopropyl'. Within th eabove Formula 1 and worthy of especial mention are themixed ethers of the types:

where a, b and x are integers taken in suflicient number to produce an ether having the prescribed viscosity, and n and n, R and R and R and R' can be the same or ditferent and are defined as in Formula 1. Preferably, when the a units are OCH CH and the b units the ratio of azb is from to 25 of a to 10 to of b.

These ethers are obtained by reaction of the alkylene oxide with water or with a glycol, desirably in the presence of a catalyst. The reaction which takes place seems to be a simple addition wherein the alkylene oxide is converted to the corresponding oxyalkylene groups or radicals. The glycol may itself be prepared by reaction of the alkylene oxide with water. Thus water can be regarded as the ultimate starting material. The molecular weight of the polymer obtained will depend upon the relative proportions of alkylene oxide and water or glycol.

From various analyses it has been determined that these polyalkylene glycol ethers are complex mixtures of compounds having polyoxyalkylene chains of difierent lengths and different internal configurations, and although the materials are characterized as monoethers, they may contain a small proportion of chains having hydroxyl groups at each end, i. e., diethers. If mixed alkylene oxides are employed as the starting material the chains will contain complex mixtures of the mixed oxyalkylene radicals in various combinations, depending upon the relative proportions of the alkylene oxides, and a given chain may have several oxyalkylene units of the same type together tertiary, in any combination of the'three.

a I a or interspersed with other oxyalkylene units in any order or combination. Thus the above formulae for the mixed ethers are merely suggestive of the types of combinations that may be found.

The important criterion from the standpoint of the invention is the viscosity of the ether, and this should be within the range from 285 to 1145 SSU at 100 F.

Thus it will be understood that there can be employed in accordance with the invention mixtures of these glycol monoethers with diethers and even dihydroxy compounds which are present in the mixture following condensation and/or etherification, but at least the major proportion and preferably upwards of 85% is the monoether. Reference is made to U. S. Patent No. 2,425,845, to ,Toussaint etal., dated August 19, 1947, which describes methods forthema'nufacture of the 'glycols and to U. S. Patent No. 2,425,755, td-Robertset al., dated August 19, 1947, which describes the preparation of the monoethers.

The polyethyleneglycol ethers having one terminal 'hydroxyl group are water-soluble and would not be employed in the compositions of the invention to aid in imparting dynamic water resistance. They and related water-soluble compounds described in application Serial No.'253,984, filed October 30,1951, now abandoned, are however elfective in improving the temperature susceptibility characteristics of the thickened lubricant of the invention and can be used as a supplemental ingredient in the compositions of this invention, to take advantage of this property.

The imidazoline should be surface-active, oil-dispersible and water-insoluble and has the following structure:

' Many of the compounds having the above general structure are also capable of improving the high temperature [The amino group preferably has 'at'least' two basic nitrogen atoms, which can be primary, secondary or Where'one or more of the nitrogens is primary, i. e., NH they can be attached at any position in an aliphatic chain or on a cyclic ringu Where one or more of the nitrogens is secondary or tertiary, i. e., -NH or,

they can be substituted in a straight or branched aliphatic chain, or in a heterocyclic ring, which can itself bear alkyl, alkylene, hydroxyalkyl or hydroxyalkylene groups, desirably in the 1-position, as in the above imidazoline ring. See U. S. Patent No. 2,655,476, dated October 13, 1953, to Everett C. Hughes and Ernest C; Milberger.

' Thus R can be a hydroxyethyl group, a mono-, dior triethylene amino group, a l-alkylene-imidazoline group,

or a l-alkylene amino imidazoline group.

'R" is an alkyl, hydroxyalkyl, alkylene-or hydroxyalkylene group, j

R, which is derived from an acid, can have from I eleven to twenty-one carbon atoms, such as undecyl, tridecyl, abietyl, pentadecyl, undecenyl, heptadecyl, ricinoleyl, and heptadecenyl. I

The alkylol imidazolines are prepared by reaction of aliphatic acids and hydroxy diamines followed by cycliza tion, in the following way:

Alkylol imidazolines in which R is from one to about six carbon atoms, such as hydroxyethyl and hydroxyisopropyl, are readily available" and are preferred. The chain length for R is dependent upon the alcoholic (polar) character of the group; the larger the number of carbon atoms, the more the group takes on the character of a hydrocarbon and loses its alcoholic character. An upper limit of about eighteen carbon atoms for R is indicated by this requirement.

Amine .Oj l -fl-hydrbxyethyl-Z-heptadecenyl imidazoline, and analogous compounds as described in application Serial No. 240,452, filed August 4, 1951, now U. S. Patent No. 2,711,393, patented June 21, 1955, have been found to be particularly effective alkylol imidazolines in the thickened lubricants of the invention. a

The amino imidazolines are prepared by reaction of aliphatic acids and polyamines followed by cyclization, in the following way:

- l n'ooon RNnomomNH, R-N N 211,0

Amino imidazolines in which R has two basic nitrogen atoms and from four to .about twenty carbon atoms, such as diethylene diamino and triethylene triamino, and the alkyl substituted N-alkylene and N-alkylene-amino imidazolines (wherein R is attached to the imidazoline- 'nucleus of the general formula through'the N-alkylene or N-alkyleneamino group), are readily available and are preferred. The chain length for R is dependent upon the basic (polar) character of the groupg-the larger the number of carbon atoms, relative tothe number of' amino nitrogens, the more the group takes on the character of a hydrocarbon and loses its basic or amine character. An upper limit of about five carbon atoms per amino nitrogen is indicated by this requirement, with about a maximum of thirty carbon atoms for the R group.

The amino imidazolines described in U. S. Patent No. 2,655,476, dated October 13, 1953, have been found to be particularly effective in .the thickened lubricants of the invention.

The presence of the polyalkylene glycol ether in an amount to obtain improved high temperature and dynamic water stability does not markedly effect the consistency of the thickened lubricant, i. e., the amount of the inorganic gelling agent to impart a given consistency to the thickened lubricant is not materially modified. Furthermore, the inclusion of the polyalkylene glycol ether will not efiect a change-in the consistency of the thickened lubricantupon storage. I i" I Due to the inorganicnature of the gelling agent, the thickened lubricant has excellent storage stability. f This is to be contrasted with. the heat susceptibility-and deterioration; of fatty materials insoap-base greases.

The preparation 'ofthe grease. is simple and readily adaptable to continuous operation, as contrasted with the In addition, the avoidance of the use of soap permits the manufacturer to be independent of the fat supply, which is important in periods in which fats and soaps are scarce and,'many times, of pronounced nonuniformity.

The inorganic gelling agent to be used in making the thickened lubricant in accordance with this invention may be any inorganic material which forms a gel with a lubricating oil and which is so finely divided as to be non-abrasive. The preferred materials are the aerogels, which may be formed from any material not incompatible With oil, such as silica, alumina, and other gel-forming metal oxides.

A series of silica aerogels which can be used as' the inorganic gelling agent of the invention are manufactured by Monsanto Chemical Company and marketed under the trade name Santocel.

Santocel C is prepared from a sodium silicate solution in the following Way: The solution is neutralized with sulfuric acid and then allowed to stand until the mixture sets to form a hydrogel. The by-product sodium sulfate is washed out by repeated washings With water. The continuous water phase in this hydrogel is then replaced by continued washing with alcohol until an alcogel is formed. In order to remove the liquid phase without a collapse of the gel structure, the alcogel is placed in an autoclave which is heated above the critical temperature of the alcohol and the pressure is allowed to increase to a point above the critical pressure of the alcohol. The vent valve is opened. and the alcohol allowed to escape. Under these conditions, the silica gel structure remains practically undisturbed and the liquid phase of the gel is replaced with e '1 I 1'. Density, grams per AR.. L'..-.'. 0.029

ARD 0.056 to 0.064

In general, AR and ARD show superior gelling ability and the As in. general are better than the CS. Silica aerogels which have been devolatilized generally have a higher gelling efiiciency than the undevolatilized aerogels.

Other types of inorganic gelling agents which may be used include a Fumed Silica marketed by B. F. Goodrich Company. It is finely divided and appears very much like an aerogel. It. is made by a combustion or vaporization process, as a source of white carbon black for the rubber industry. 'The particles are several microns in size and porous in nature.

Another material is Linde Silica Flour marketed by Linde Air Products Co. It is very similar in physical appearance to the silica aerogel. The particle size of the silica is purported to be 0.01 to 0.5 micron and to be manufactured by. burning silicon tetrachloride and collecting the combustion product on cool plattes analogous to air. The material'is then reduced in particle size by blow-g ing it through a series of pipes containing sharp bends with jets of compressed air. Santocel C has a secondary agglomerate particle size of about 3 to 5 microns.

Santocel A is prepared as set forth for Santocel Cup to the point of removal of the product from the autoclave.

This material is run through a continuous heating chamher where it is heated for A2 hour to a temperature of about 1500 F. to eliminate the last traces of volatile material. It is then broken down in a reductionizer or micronizer to a particle size of about inch in diameter. The solids content of the original hydrogel used in preparing Santocel C is approximately 25% higher than that of Santocel A.

, AR is a modification of A, differing only in that the material is reductionized to about the same particle size for A. CDv is reductionized before being devolatilized.

CDvR differs slightly from CDV in that the CDvR has been devolatilized just after heating in the autoclave and then reductionized. It differs from CDv inthat the. latter.

is reductionized before being devolatilized. I

The primary differences between the As and the Us are as follows:

(1) The Cs are prepared from a sodium silicate solution containing 25% more silica than the As; 'Therefore, in general the -As are lighter and cornposed of smaller particles than the Cs. g p

(2) The As have undergone a devolatilization step in their preparation.

The following are the bulk densities of preferred silica aerogels the production of carbon black. The particles are throught to be aggregates or clusters of particles rather than of spongelike character.

Still another inorganic gelling agent known is Ludox silica from Du Pont which is known as a silica sol, and silica derivatives thereof. It has a particle size of the order of 0.01 to 0.03 micron.

In preparing thickened lubricants it is necessary to removethe' Water from the sol and replace it with an oil. This is possible by formulating the lubricant and removing the water by flash distillation or azeotropic distillattion.

No attempt is made to enumerate all of the inorganic gelling agents which will be suitable, nor to present examples of all of them since the novel aspects of the invention reside in water-proofing the lubricant rather than the use of novel gelling agents, per se.

The lubricating oil to be used in the process may have any lubricating viscosity. It may be raw oil, aCid refined, or solvent-refined, as required for the particular lubricating need.

The nature of the base oil has been found to make little difference in the relative consistencies of the thickened lubricants and conventionally (acid) refined oils produce slightly thicker lubricants than solvent refined oils. Excellent working stability is obtained regardless of the type of the base oil. An increase in the viscosity of the base oil, as might be expected, brings increased viscosity to the thickened lubricant and minimizes bleeding. The change is relatively small and fairly linear. The viscosity of the oil does not affect the working stability of the lubricant.

- uct. can S' having a wide variety of consistencies. 7

The amount of the inorganic gelling agent, as might be expected, affects the consistency of the thickened lubricant in that an increase in its concentration brings a corresponding increase in consistency. The range is fairly linear and the amount of the gelling agent can be selected with relation to the consistency desired in view of the information in the following examples. While the difference is slight, the lubricants made with lower con.-

' ce'ntrations of gelling agent possess better working stability, while lubricants with larger amounts of gelling agent show slightly improved temperature susceptibility characteristics. The bleeding tendencies are decreased by increasing concentrations of the gelling agent.

In general, the properties of the thickened lubricants are remarkably independent of the composition variables and are not critical. The relative concentration of the gelling agent effects the most significant alteration, particulai'ly with regard to the final consistency of the prod- This permits the manufacture of thickened lubriwide variety of water-insoluble polyalkylene glycol others can be. employed in accordance with the inveni j a tlon. The molecular weight and chain length of the ether Q. ']?3 are not crltlcal except as they affect viscosity. Any'polyi J I H alkylene glycol others having a viscosity at 100 F. within 1 the range of 285 to 1145 SSU can be employed in the 5 R' [[Q CH,CHQIG[O OH1 OHIB]0H composrtionof the mventlon. 5 V I H a The following exemplify several preferred polyalkylene O glycol ethers in accordance with the invention: (8) (1) n-[lo-omo12001141lo ely-c1111]on R-[O- OHzfiJH-lPH 10 OH: CH1 p R in the above formulae can be methyl, ethyl, or isopropyl, ,g and x isan integer taken in suflicient number to produce an ether having the prescribed viscosity. (3) d The above polyalkylene glycol ethers can be mixtures R[OCHaOH]OH of ethers in which x is variable to produce a material having the prescribed viscosity. The mixed polyethylene- 1,2-propy1ene glycol ethers are preferred. 2O Exemplifying specific monoethers within the scope of the invention are the Ucon LB and LB-X series of poly- (5) alkylene glycols. These are mixed polyethylene-1,2- 0H propylene glycol monomethyl ethers, some of which have CH1 CH5 the following properties:

TABLE II LB-285 LB-385 LB-525 LB-625 LB-1145 I Viscosity: Saybolt Seconds at- 210 F 100 F 0 F- Centistokes 210 100 F.-- 0 F g 0 Viscosity Index (A. s. T. M. 13-50741) 145 144. 143 141 137 Pour Point, F. (A. s. '1. M. D-97-39) -40 35 -30 -20 Flash Point, Open Cup, F. (A. S. T. M. 13-92-45) 425 430 430 430 430 Do 490 500 505 510 510 Refractive Index, ND 1. 443 1.449 1.450 1.450 1. 451 Density, g./cc. at V 210 F 0. 930 0.935 0.933 0.939 0 942 0. 975 0. 930' 0. 933 0. 984 0 937 00 F 0.992 0.995 1. 000 1.001 1. 003 Coeflieient 0! Expansion per F. at 68 F 00042 00042 00042 00042 00042 Specific Gravity, 20 20 O 0.991 0.995 0.999 1.000 1 002 Pounds per Gallon, 50 F 3. 27 3.30 s. 34 3.35 s. Water, percent Ash, percent (A. S. T. M. D4824 Carbon Residue LB soo-x LB400X LB-550-X LB-650-X 02. 7 74.3 93. 1 100 300 400 r 550 050 13, 330 p 20, 000 40, 400 50, 500 11. 0 14.1 13. s 21. 9 05. 0 s5. 0 a 119 141 4, 000 5, 300 8,800 11, 000 400 r 18, 500 29, 000 47, 000 Viscosity Index (A. s. T. M. 13-50211}: "i 12 1 41 "iii "140 Pour Point, 9 F. (A. s. T. M. D-97-39). -25 20 Flash Point, Open Cup, F. (A. S. T. M. D-92-45 490 490 490 490 Fire Point, Open Cup, F. (A. S. T. M.

D-92-45 535 595 000 005 Refractive Index, NDWL; 1. 452' 1. 453 1. 454. 1. 454 Denslty,.g./ce. at-

. 210 F 0. 933 0 930 0. 933 0.939 7 100 11; 0.979 0 981 0. 934 0.985 Coefllclent oiExpansion Per F. at 68 F. 00042 00042 00042 00042 Specific Gravity, /60 F 0. 997 0. 999 1. 001' 1.002 Gravity, API, 50 F 10. 5 10.1 9. 9 9. 3 Pounds per Gallon, 00 F"-.- 8.80 8.32 8. 8. 34 Water, percent g) Ash, percent (A. S. T. M. D-482-43) Carbon Resldue.., 0) (t) 1 Les than 0.25%. .Less than-0.017

Less than 0.01

The-polyalkylene glycol ether should be oil-dispersible. The polyalkylene glycol ether is incorporated in 'the thickened lubricant'in an amount to impart high temperature stability to the grease. Ordinarily, a concentration of polyalkylene glycol ether ranging from- 0.25 to about 2.5% by weight ofthe thickened lubricant gives satisfactory results. There is no reason to employ more polyalkylene glycol ether than is necessary, but excessive amounts do no harm, and amounts up to or even higher have been successfully employed. -In general, the concentration of the irnidazoline should be at least about 2.5% by weight of the aerogel but will vary depending upon the water stabilizing effect desired, the nature of theiparticular compound selected, the amount and nature of the gelling agent used, and the economics involved. Both static and dynamic water resistance tend to increase with time, so that an amount of imidazoline may be inadequate-to impart the desired water resistance at once, yetafter the grease has aged for a few weeks or months it may display excellent water resistance. Preferably, from 4 to 14% imidazoline by weight of the aerogel is used, as such amounts usually impart excellent water resistance at once. A cheap compound, of course, can be used in much larger quantities than can expensive compound, at the same total cost for the lubricant.

In some instances, the thickened lubricant may not display a long life when used continuously at high temperatures. A breakdown in high temperature stability at high temperatures if it appears is due to a decomposition, through oxidation, and in such circumstances, it is desirable to include an antioxidant in the composition. Conventional amine antioxidants which are more readily oxidized than the components ofthe lubricant can be employed for this purpose. Tetramethyldiaminodiphenylmethane, available under the trade name Calco MB, is a particularly desirable antioxidant. Only small quan titles are required, and ordinarily an amount ranging from 0.1 to about 1% by weight of the thickened lubricant is ample. There is no reason to employ more antioxidant than is necessary to. produce the desired effect, 'but excessive amounts do no harm and amounts up to 5% can be used, if desired.

The composition is made simply by mixing the inorganic gelling agent, the oil, the polyalkylene glycol ether, the cationicwater stabilizer and the antioxidant in any order or manner. 1

In one embodiment, the polyalkylene glycol ether and, desirably, the cationic water stabilizer and antioxidant, canbe incorporated with the inorganic gelling agent either by mixing directly, or if desired, by dissolving them in a volatile hydrocarbon solvent, such as pentane, adding oil, mixing the solution with the inorganic gelling agent, and then evaporating the solvent.

. Generally, the polyalkylene glycol ether and, optionally, cationic water stabilizer and antioxidant are dispersed in the oil and the inorganic gelling agent added thereto and mixed therewith. Any simple mixing technique can be employed, and, if desired, the mixture can be homogenized in a colloid mill, although this is not necessary. a

The mixing temperature is not critical, but is preferably in the range of 100 F. to about 250 1 At higher temperatures grease yield is affected. Mixing temperatures of 140 to 160 F. are preferred.

Mixing is continued until the components are thoroughly dispersed in the oil and the consistency has attained the desired level. Any type of mixing is satis factory. High shear supplemental mixing at a high tern perature is useful. I

The composition of the invention is not limited to the oil, gelling agent, imidazoline and polyalkylene glycol ether. Any of the materials conventionally added to lubricants and greases can be i'ncludedf The expression consisting essentially of 'as' used herein is intended to refer'to the components which are essential to the composition, namely, the oil, the inorganic gelling agent, the imidazoline,'and the polyalkylene glycol ether, and the expression does not exclude other components from the composition which do not render it unsuitablefor lubri cation, suchmaterials being-for instance, the antioxidant, high polymers to modify viscosity or viscosity index, materials to impart tackiness, lubricating solids such as graphite, antioxidant additives, corrosion inhibitors of various types, sulfur, additives to render the lubricant suitable for use in gears, for cutting, grinding, etc.

The following examples illustrate preferred embodiments of the invention. a

In the examples which follow the high temperature stability of the grease was determined by measurement of micropenetrations before and after heating to 400 F. in the block test. The grease was prepared for the determination of high temperature stability by placing approximately cc. of grease in a ml. beaker. The beaker was heated to the test temperature in an aluminum block furnace. This furnace consisted of a solid block of aluminum heated by internal electrical heaters. Six holes, each large enough to accommodate a 150 cc. beaker, were drilled in the top of the block, together with a thermocouple, so that a measure of the temperature of the block could be obtained. In this manner, six beakers could be heated simultaneously. The beakers containing the grease were placed in the aluminum furnace and held there until the equilibrium temperature of the grease reached 400 F. The samples were stirred at five-minute intervals during heating. After this the grease was allowed to cool to room temperature overnight and then was stirred vigorously with a spatula. Micropenetration measurements were obtained on the grease before and after the test procedure. The cycle was repeated as many times as desired and the results are expressed by plotting the actual penetration against the number of cycles.

The static waterstability was determined as follows: A 2 x 2 inch stainless steel plate was coated with a uniform layer of the grease, following which the coated I formed. If free water remained unemulsified this was noted. Whether the emulsion was an oil-in-water or water-in-oil type wasreadily apparent,for the water-inoil emulsion was shiny in appearance while the oil-inwater emulsion had a dull matte surface. If the 50 weight percent of water had been completely emulsified and no emulsion inversion had occurred an additional 50% of water on the original weight of the grease was added, the grease worked an additional 300 strokes, in the presence now of 100% water, and another Shell penetration obtained. The grease was considered to have good dynamic water resistance if, at the conclusion of the second 300 stroke working cycle, in the presence of 50% water, the emulsion had not inverted, i. e., the emulsion remained of the water-in-oil type, whether or not the water added had been completely emulsified. Dynamic water resistance was considered excellent if inversion of the emulsion had no occurred at the end 'of the third 300 stroke working cycle, in the presence of 100% water.

The following results are typical of the application of this test to conventional greases:

TABLE III a 1 Percent Calco MB 0.5 W1etmtlons Solvent-extracted bright stock (78 SSU at. Base grease Comments 210 F.) 85.75

1111- 50% 100% 5 p tial H H10 =1Tetramethyldiaminodiphenylmethane. V V p The grease was subjected to the static water stability Lithumh dro 129 140 146 At 50 all water emulsion V stefarate xy wlth free water in drops. test and rated as P 9 1 V l tg-i Free Water at The storage stability of the grease was determined 155 166 free men 10 by allowing it to age for six months, whereupon it was M a 182 206 Free waten W/OJ tested 101 dynamic water resistance with the following 141 191 Do} results: I V Soda 120 77 Do. s Aerogel (Santocel 145 142 Emulsion inverted to O/W. Ongmal Shell penetration ARD) (300 strokes) 1'18. IWIO means Watermofl emulsion 0 Shell penetration after second' 7 IO/W means oil-in-water emulsion: 300 )Stroke y 136 V ter These results show that the soap base greases tested were Wa 1 a r 1 resistant to water, but the aerogel grease was not. Ac- Type of emulsion ZZEQ H (fi cordingly, an aerogel base grease that passes the test can Shell {ratio after third a'mmg be regarded as the equal of a soap base grease in dynamic 300 p 2 k n l water resistance under these test conditions, which closely t s m e cyc e a 13 0 approximate field conditions. T Wa "'I'f'"? Waiepimofl The ability of the grease to emulsify with free water '9 0 emu 5111 (fr waterr a to some extent is desirable, and therefore in evaluating un 5: dffn the test results it is not necessary that the greasetnot t V a V emulsify with water, but merely that it not emulsify with a The aged grease had excellent dynamic wafer resist Water to the Point Where Inversion to an p ance. This shows that the amount of imidazoline was emulsion occurs. a 9 too low to' impart dynamic water: resistance at once, The Workmg mechamcal stablllty of the greases was but was adequate afteraging. Storage stabilityobviously evaluated by 10,000 strokes working at room tempera wasrexceuent V I a ture in the ASTM grease worker and by four hours i a e 2 t 1 at room temperature in the grease WOIklflg assembly Ex mp1s o 2 wherein the grease sample was sub ected to the severe A group of greases was prepared having the following working afforded byelose intermeshlng gears in an enf rm l ti n; p H closed space. This approximates many field conditions .Percent for general ball and roller bearing and transmission santoce1ARD 9.0 T greases. The measurements include a Sohio micropene- U lubricant LB 625 r 2.0 Y tration of the grease before working, a Sohio micropene- Amine() 1 Amount indicated tration after working, plus a Sohio micropenetration after in table below; the grease has been allowed to stand for approximately Paratac ,1 0 1 J twenty-four hours, and another after the setup in grease Paraflow 0.5 body has been disturbed by vigorous stirring with a Ortho1eum 300 0.5 spatula. The last two measurements ofier further data v Solvent extracted bright stock (2000 on the ability of the greases to resist mechanical break- SSU at 100 F.) 89. 2 downl-B-hydroxyethyl-2-heptadecenyl-imidzizoline. j p p Example 1 An isobutylene polymer sold by the Enjay Company, Inc.

and commonly used in compounding greases. A grease was prepared of the'following formulation d A Frie del-graf las rea c tio r l prodgct, useful as a po point e I'ESSfln 3111 80 e I! 8, 0111 8.11 110. V at a PromsS temperature f An antioxidant for mineral lii bricat ingxiils.

Percent SSiG? 2vloumfie percclen solvent-extracted: brightt stotck t'lg a. o an V0 111116 8130811 S0 ven -ex rac e Santocel bright stock, 250 SS0 at 210 F. p 7 Ucon lubricant LB-300-X 2,0 Amine 1 5% by Weight f the 5 The oil-soluble additives, 1. e., the Paratac, Paraflow Paratacz L0 and Ortholeum 300, were dissolved 1n the oil. The 011 Paraflow 3 0'5 was brought to 95 F., the Amine O and Ucon added 1 1 B h drox 12 heptadecenyl imidazofine with thorough mixing and then the Santocel was. blended 2 An ibutyslyeneypplymer Sold by the Emmy Company, Inc. in as rapidly as 1t was absorbed 1n the mixture. The a d co m y used c mp g greases. total -m1XlIlg time was sixty minutes at the temperature A Fnedel-Crafts reaction product, useful as a pour point t d th t bl v depressant and sold by the Enjay Company, Inc. ma 6 m e a V T L IV.

Temp., 1 Final ASTM peasa Percent Ucon grease Initial 24 hr. Example No. Amlu LB625, 4 temp., Shell Shel 0" percent Initlaloil Final oil F. pen. ()sttokes str0kes bat blend 0 2 s5 98 110 115 114 264 271 4 2 p 93 108 124 133 282 290 s 2 94 95 104 124 137 276 298 10 2 99 95 107 139 154 306 312 11 2 95 97 110 125 142 302 s15 12 2 96 96 100 09 239 24s 12 2 95 95 108 107 117 272 295 13 2 97 92 10,6 125 t, 152 302 ,321 14 2 97 98 v 159, 169 .325 32s 1 Based on weight of Santocel ARD.

The table shows that in manycases the grease yield decreases as the amount of Amine increases and 11118 is a linear decrease asis evident when the results are plotted on a graph. It would be concluded from this data that the smallest amount of Amine 0 required to give the desired water resistance should be employed. V g

The static and dynamic water resistance properties of these greases was evaluated by the tests described above and are summarized below:

TABLE V Dynamic water resistance Percent V Example Amine StatieElO-mmute boiling Shell pens.

No. 0 1 water test Comments Orig. 100% H20 0 Fain-considerable bleeding 114 282 Oil-in-water emulslon-inversion; complete and sep. Santocel. brealrdown of grease. 4 Good-surface slightly 133 124 Water-m-oil emulsion; free unemul. H2O.

whitened. 8 150 113 Do. 10 150 113 D0. 12 99 104 D0. 14 Very goo 169 140 Do.

1 Based on weight of Santocel ARD.

It is evident that as little as 4% Amine O by weight of the Santocel was suflicient to impart good water resistance. The results for Examples 3, 4, 5, 7 and 10 are to be contrasted with Example 2 which did not contain Amine 0 but did contain 2% of the Ucon lubricant. This shows that the Ucon lubricant alone, even at a concentration of 2% is not able to impart the necessary dynamic water resistance.

As an additional comparison two greases were prepared containing 5 and Amine 0, respectively, by weight of the Santocel, and no Ucon oil. These greases had the following composition.

These greases were subjected to the static and dynamic water resistance and the high temperature stability tests. Example A had borderline static stability and very poor dynamic water resistance. Example B had excellent static and dynamic water resistance. Both these greases showed very poor high temperature stability. This shows that very large amounts of Amine O in the absence of Ucon oil are required to give an adequate dynamic water resistance, but that when such large amounts of Amine O are used, the grease has very poor tempera ture susceptibility properties.

In contrast, Examples 2 to 10, inclusive, passed th high temperature stability test.

p The working stability of Examples 2 to 10 was deter mined by the four hour test in the gear grease worker The results obtained appear in the following table:

The changes of pentration shownin the table are of an order of magnitude indicating satisfactory mechanical stability. In fact, several of the greases exhibited a stiffening tendency, as exhibited by the negative penetration change after the four hour test period.

These results show that greases containing Amine 0 alone even in amounts as high as 15% by weight of the Santocel or a Ucon lubricant (mixed polyethylene-1,2- propylene glycol monomethyl ether) alone have either satisfactory dynamic water resistance or satisfactory high temperature stability, but not both. On the other hand, greases containing both the Amine O and the Ucon oil have excellent static and dynamic water resistance as well as good high temperature susceptibility properties even though the amount of Amine O is as low as 4% by weight of the Santocel and the Ucon oil is in the same amount as when used alone. Evidently in the presence of the Ucon oil the Amine O. is more effective in smaller amounts to impart dynamic water resistance while not afiecting high temperature stability. The same effect is not obtained when diethylene glycol monoethyl ether (Carbitol) is substituted for the'Ucon oil, showing that this effect can be uniquely attributed to the polyalkylene glycols of higher molecular weight.

' This'is shown by the following:

Six greases were prepared having the following formulation:

SSU at 210 53.5 volume percent solvent-extracted bright Stock (250 SSU at 210 F.).

'saryy in-thedynamic water test.. This shows that Carbi- TABLE VII Initial 24 hr. 24 hr. ASTM Example Amine Shell Shell penetrations N o. 1 penetrapenetration tion 0 strokes 60 strokes Percent 1 Based on the weight of the Santocel. I

The greases were tested for high temperature stability, and showed satisfactory high temperature stability characteristics after five cycles.

Furthermore, those greases containing the higher amounts of Amine O which had given low grease yields stifiened with the heating and for the times indicated in the table;

ing formula:

16 ene glycol units,,is 'not-asrefiective as the higher polyalkylene glycol ethers such as the Ucons, which are polymers of ethylene and LZ-prOpyIene glycol units, incooper'ating with the'Amine fO to give good dynamic water resistance. 7

' Examples 13 to 17 Five grease compositions were prepared of the follow- 1 8% by weight of Santocel. 241% 51 o1nme percent 78 SSU at 210 F., 63.5 volume percent 250 SSU at a The oil-soluble additives were dissolved in the oil, then the Amine O and Ucon were mixed in and finally the Santocel was added to the blend incrementally as rapidly as possible.- Mixing was continuedat the temperatpre TABLE IX Bath temp., F. Grease temp, F. Shell pens., time in minutes Exfaqmple Initial Final Initial Final 30 i 14.; 15o 13s 1 Mixer oil bath temperature and grease temperature accidentally allowed to rise to F."

during the test, compensating for the low yield therein.

The Waterv resistance characteristics of the greases were checked by a static water test and the dynamic Water test in the ASTM worker. The results are shown The results for Examples 13, 14 and 16 show that no efiect in grease yield is obtained by increasing the processing temperature from 95 to ISO-160 F. When the processing temperature is increased to 250 F. a noticecharacteristics.

in the following table: V 60 able drop in grease yield is apparent. The immediate TABLE VIII Dynamic water resistance Percent ExlaImple Static 30-minute boiling water test Shell pens.

Results Orig. 100% 6 Very poor-considerable emulsion-loses grease characteristics. 8 Poor-considerable emulsionloses grease-like Oil-in-water emulsion-inverted. Water-in-oil tree HzO-5till adhesive. Water-in-oil emulsion small amount free Hz0-Stlll adhesive.

Based on weight of Santocel ARD.

If the greasedid not pass the static test, the dynamic water test was nbtcarried out since this would have been useless. V

The results show that with Carbitol at least 10% Amine O is necessary for satisfactory performance in the static boiling water and that at least 14% is necestolydie thylene glycol monoethyl ether having two ethylpenetration values for Examples 13 and l4 are lower than the values obtained after twenty-four hours. 'This is attributed to the fact that'these greases are stifier while hot; 7 Example 15 was too soft after one hundred and twenty minutes of paddle mixing to fall within the range of penetrometer measurement. Therefore it was further processed by one pass through a-homogenizer. This water achieved a distinct increase in grease consistency, showing that a homogenization is quite effective as a means for increasing the grease yield following processing at high temperatures.

Another portion of the greaseof Example 15 was recycled through a gear pump. The grease possessed an original Shell penetration of 242. After recycling in a gear pump for sixv to seven minutes, the grease was pumped out. The Shell penetration was 183. After repeating the cycle again the Shell penetration reached 171, but the grease temperature was 122 F. After permitting the grease to stand overnight, a Shell penetrationobtained at "room temperature was 180. i This shows that gear pump cycling also is effective to increase the grease yield after'processing at a high temperature. 7

The grease prepared using the 78 ,SSU bright stock was processed at 95 F. and the mixing time was limited to sixty minutes. The ASTM penetrations appear below:

The working or mechanical stability of these greases was evaluated in the ASTM worker and by four hours working in the gear working assembly. The results are shown in the following tables:

X .4 10,000-STROKE WORKING STABILITY ASTM Pens., N0. Strokes APe'n. Ex. Processing r No. Temperature p V 13-- 95 F 319 334 327 324 325 323 11 14-. 0 F 335 342 327 319 32/1 @316 7- -26 15-. 250 F. (110- 267 319 333 335 338 1 342 52 23 mogenv ized). 16-- 160-170 F. 330 337 340 339 334 343- 7 "(s a pum'pedL. 17-- 95 F 325 339 332 332 332 338 14 1 1 After sanamg'tiasnanttabvam m, pe -29s.

TABLE XI LABORATORT GEAR WORKING STABILITY Sohio mleropenetrations A penetration Example N 0.

Original 4-111. 24-hr. 24-hr.- 0-4 hrs. 0-24 hr.-

stir Stir All of the greases had very satisfactory performance in each of the tests.

The dynamic water stability resistance of the greases was evaluated with the following results:

7 TABLE X11 7 nYnAMIo WATER STABILITY Shell penetrations x Approxi- Example No. I A pen. mate per- 600 strokes cent H10 w. 100% emulsion 14o 41 so 121 64 134 -11 '55 135. 45 65 '154 33 In all cases the emulsions remained water-in-oil and the products lretained their 'greaselike characteristics even though the grea's'es emulsified with approximately 55 to 70% of water.

Another sample of Example 14 was subjected to incremental addition'of water withworking in the same test. The grease became stiffer upon emulsifying the first 5% of water into the grease structure. Beyond this'point the consistencyof the grease was fairly stable. The test was halted after 80% water had been added. The grease continuedfto emulsify water until 60% waterhad been added after which free water remained present in the worker.

The greases of Examples 13, 14, 15 and 17 were evaluated for high temperature characteristics and were runinduplicate for five. complete cycles. The greases of Examples 14, .15 and 17 showed excellent high temperature stability. The grease of Example 13 had borderline performance which is attributed to the low process temperature used. The high temperature stability would on the entire top race and inside face of the bottom race. The grease of Example 13 was given an A rating in the test. In comparison, an aerogel grease of the same formulation but "without the Ucon oil failed the test with a D rating.

I The ,grease of Example 14 was evaluated by the ANQAS bearing washout 'test to evaluate the resistance to"water washoutof'the grease from a rotating bearing.

7 The duration of the ltest is one hour; after whic hthe loss in weight of the grease from the bearing is determined. The'test ran the full hour and most of the grease in the bearing had become emulsified with water. Hardly any grease was evident'in the wash water. In contrast, a test riin with an 'aerogel grease of the same formulation without the Upon oil 'ran for approximately ten minutes, after which failure was evidenced by loud squealing noises from the bearing. Almostrall of the grease had emulsified and inverted and the washout from the bearing itself appeared in the Wash Water as a milky emulsion.

The thickened lubricants of theinvention are useful in many field grease applications. In the critical field of wheel bearing lubricants, these greases have performed very satisfactorily. Other successful field applications include chassis lubrication, general ball and roller bearing applications, foundry ladle trunnion bearings, phonograph bearings, textile spinning wheels, cam followers, kiln car bearings, farm equipment, worm gear-radar antennae, outdoor playground equipment, shaker screens and ring gears and mixing vessels.

The greases of the invention are characterized by their case and reproduceability of preparation and their high static and dynamic water resistance and high temperature consistency stability. In addition they have excellent oxidationv resistance and mechanical stability. All of these are requisites for a multipurpose lubricating grease.

Testing the high temperature stability of the thickened lubricants of the invention by heating the greases to 400 F. is an extreme test inasmuch as the highest temperature to which a grease is subjected under even extraordinary conditions of use is about 300 F., but the temperature was adopted as a suitable test standard because a grease stable at 400 F. definitely will have the stability necessary to withstand heating to 300 F. It will be understood that for normal purposes the thickened lubricants of the invention need not be stable at temperatures above about 300 F. and that the greases of the invention at least meet this requirement. Where the term high temperature stability is used, it will be understood to mean that the thickened lubricant is stable againstloss of consistency at temperatures of atrleast 300 F.

The Shell penetrations are in accordance with the Shell 'Microcone Penetration Test, Institute Spokesman (NLGI), volume VI, Number 12, page 1 (1943). I

The Sohio micropenetration technique employed required a microcone and cup. The microcone was specially built,;and its dimensions are compared in Table II with those of the standard ASTM cone, ASTM Designation 217-48 described on page 143 of the November 1948 edition of D-2 Specifications for Petroleum Products.

The cone and grease cup employed in obtaining the test results required a minimum sample size of 35 ml.

TABLE XIII MIOROCONE DIMENSIONS ASTM Cone

Gone height/cup depth. Weight of assembly, gms Weight of assembly/sq. mm. cone surface 1 Calculated.

, 20 of 285 to 1145 SSU, and a water-insoluble oil-dispersible cationic surface-active imidazoline having an aliphatic group substituted at the 2-position and a hydrophilic group substituted at the 1-position of the imidazoline, said glycol ether being in an amount within the range from 0.25 to about 2.5% by weight of the thickened lubricant, and said imidazoline being in an amount within the range from 4 to 14% by weight of the inorganic water-susceptible oil thickener, each being 'in amounts sufiicient in combination to impart high temperature stability and dynamic water resistance to the thickened lubricant. i

2. A thickened lubricant in accordance with claim 1 in which the polyalkylene glycol ether is a polypropylene glycol ether. a i i 3. A thickened lubricant in accordance with claim 1 in which the imidazoline is l-B-hydroxyethyl-Z-heptadecenyl imidazoline V 4. A thickened lubricant in accordance with claim 1 in which the inorganic oil thickener is a silica aerogel.

5. A thickened lubricant of high temperature stability and good dynamic water resistance, consisting essentially of a mineral lubricating oil of lubricating viscosity as the 'major component, a finely-divided silica aerogel in an amount'suflicientto impart a grease consistency to the oilfa water-insoluble oil-miscible mixed polypropylene glycol ether having one terminal hydroxy group and a sufficient proportion of oxyalkylene units of at least three susceptible oil thickener in an amount sufiicient to impart a grease consistency to the oil, a water-insoluble oilmiscible polyalkylene glycol ether having one terminal hydroxy group and a suflicient proportion of oxyalkylene units of at least three'carbon atoms to impart waterinsolubility, and a viscosity at 100 F. within the range carbon atoms to impart water-insolubility, anda viscosity at F. within the range of 285to-1145 SSU,'and a water-insoluble oil-dispersible cationic surface-active imidazoline having an aliphatic group substituted at the 2-position and a hydrophilic group substituted at the 1- position of the imidazoline, said glycol ether being in an amount within the rangefrom 0.25 to about 2.5% by weight of the thickened lubricant, and said imidazoline being in an amount within the range from 4 to 14% by weight of the inorganic water-susceptible oil thickener, each being in amounts sufiicient in combination to impart high temperature stability and dynamic water resistance to the thickened lubricant.

6. A thickened lubricant in accordance with claim 5, in which the imidazoline is l-fl-hydroxyethyl-Z-heptadecenyl imidazoline;

7. A thickened'lubricant in accordance with claim 5, in which the polypropylene glycol ether is a mixed polyethylene -1;2-propylene glycol ether.

References Cited in the, file of this patent Q UNITED STATES PATENTS 2,554,222 Stross May22, 1951 2,573,650 Peterson Oct. 30, 1951 2,652,365 Moore et al. Sept. 15, 1953 2,655,476 Hughes et al., f Oct. 13, 1953 2,711,393 Hughes et al. June 21, 1955

Claims

1. A THICKENED LUBRICANT OF HIGH TEMPERATURE STABILITY AND GOOD DYNAMIC WATER RESISTANCE, CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL OF LUBRICATING VISCOSITY AS THE MAJOR COMPONENT, A FINELY-DIVIDED INORGANIC WATERSUSCEPTABLE OIL THICKENER IN AN AMOUNT SUFFICIENT TO IMPART A GRESE CONSISTENCY TO THE OIL, A WATER-INSOLUBLE OILMISCIBLE POLYALKYLENE GLYCOL ETHER HAVING ONE TERMINAL HYDROXYL GROUP AND A SUFFICIENT PROPORATION OF OXYALKYLENE UNITS OF AT LEAST THREE CARBON ATOMS TO IMPART WATERINSOLUBILITY, AND A VISCOSITY AT 100*F. WITHIN THE RANGE OF 285 TO 1145 SSU, AND A WATER-DIVIDED INORGANIC WATERCATIONIC SURFACE-ACTIE IMIDAZOLINE HAVING AN ALIPHATIC GROUP SUBSTITUTED AT THE 2-POSITION AND A HYDROPHILIC GROUP SUBSTITUTED AT THE 1-POSITION OF THE IMIDIAZOLINE, SAID GYCOL ETHER BEING IN AN AMOUNT WITHIN THE RANGE FROM 0.25 TO ABOUT 2.5% BY WEIGHT OF THE THICKNED LUBRICANT, AND SAID IMIDAZOLINE BEING IN AN AMOUNT WITHIN THE RANGE FROM 4 TO 15% BY WEIGHT OF THE INORGANIC WATER-SOLUBLE OIL THICKENER, EACH BEING IN AMOUNTS SUFFICIENT IN COMBINATION TO IMPART STABILITY AND DYNAMIC WATER RESISTANCE TO THE THICKENED LUBRICANT.