US2832739A - Ureido thickened greases - Google Patents

Description

and to the method of preparing same. .it relates-to novel greases comprisingv a lubricant vehicle such as silica gels.

lubrication at elevated temperatures.

United States Patent -UREIDO THICKENED GREASES Edward A. Swakon, Hammond, Ind., assignor to Standard Oil Company,'Chicago, 111., a corporation of Indiana N Drawing. Application June 13, 1955 .Serial No. 515,257

13 Claims. (Cl; 252-49.6)

The present invention relates to novel lubricant greases More particularly,

thickened with certain high melting ureido compounds. Greases of this type have demonstrated exceptional stability at elevatedtemperatures.

As lubricants are required toperform at higher and higher temperatures because of increased speeds of engines and machines, the advent of jet propulsion, atomic energy as a source ofppowenetc, it has become increasingly .diflicult to preparegreases fulfilling the requirements of such lubricants. In attempting to provide such greases, the art has progressed from the use of petroleum lubricant vehicles thickened with metal soapsof long chain fatty acids, e. g. lithium hydroxy-stearate, to more thermally stable synthetic lubricating oils such as the aliphatic diesters of dicarboxylic-acids, silicone polymers,

etc., thickened with such soaps or inorganic materials The progress of thickener research has not in general, however, kept pace with the development of lubricant vehicles. And at temperaturesas high as 400 to 450 F. thereare few if anygreases available which will retain their consistency and lubricity for any substantial period of time.

In recent years various synthetic lubricant vehicles, e. g. the silicones, fiuorocarbons, etc., have been foundto be potentially valuable for use in greases employed at very high temperatures because of their thermal stability and relatively low volatility. Unless, however, a thickener having substantially the same degree of thermal stability is available to produce a grease from such an oil, they are of little use.

It is a-primary object of the present invention to provide lubricant greases which are stable and give excellent A further object is to provide :a readily producible series of greases embodying a novel class of thickening agents capable of yielding lubricants particularly suitable for use at temperatures of fromabout 250 F. to about 450 A particular object of the present invention is to provide greases which are effective lubricants at temperatures as high as a about 450 F. for substantial periods of -time. These and additional objects will be apparent from the 'tollowingdetailed description.

Copending Swakon andBrannen application for Letters 'Patent S. N. 318,321, filed November 1, 1952, now US. 2,710,839, discloses-andclaims certainvery high melting aromatic ureas, diureas, amides, and diamides, all of which contain at least one silicone polymer oils, as well as other known lubricant I vehicles, to produce greases which are stable and display excellent lubricant properties over a wide range of temperatures. Whereas silicone polymer oils are particularly 2,832,739 Patented.Apr-.29, 11958 preferred for use. in. greases. employed at temperatures as prising mixtures .of atleast two different aryl substituted meats and/ or diureas are described and claimed. .Thus,

inv accordance with the invention described in said. application, mixtures of aryl. substitutedureas,preparedlbynreacting (1) at least twoditferentaryl monoisocyanates with :at least one aryl amine (monoordi-amine) .or (2) atleast t-Wodifferent aryl monoamines with at least one aryl .isocyanate Y (mono-. ordiisocyanate) It has now been. found thatgrease compositions exhibiting good rheological properties, .having high thermal stability and possessinghighdropping points and/or.,.nomelt characteristics can be. obtained by thickeningasuitable oleaginous lubricant vehiclewlth. from about 2% to/about 50% and preferably fromabout 5% to about 40%,-by weight,- of a ureidocompound having-the general formula in which Z and Z are terminal reactive radicals selected from the group consisting of .NH and-NCO' radicals alkylene groups are further characterized-as straight and/ .or branched .chain, radicals having from ,1 to i about-30 .carbon. .The .arylene and substituted ar-ylene.radicals can be mononuclear and/or polynuclear-such as phenylene,

.biphenylene,. naphthylene and anthrylene radicals.

.The ureidocompounds are readily prepared by heating a mixture of the polyamine and the polyisocyanate. in equivalent weight ratios of from lzx to x11 Where x can be anumber rangingfrom-Z to 4, and preferably inlthe equivalent weight ratio of 1:1, at a temperaturew'ithin the range of room temperatu-ret about -F.) to about 350 F. .For example; -when"diamines-and diisocya'nates are the reactants the equivalent weight ratioca-nbe varied from 1:2 to 2:1, While whenltr-iamines and triisocyanates are the reactants the equivalent weight ratio can be varied One or more'polyamines can be reacted with one or more polyisocyanates to give mixed polyureido compounds. Asindicated in the general formula above, the herein described ureido compounds can have one aminoand one isocyano-terminal radical or both terminalradic-als canbe the same, i. e. either amino rradicals or-isocyano radicals depending upon the equivalent weight ratio of the reactants used. Thus when the polyamine and the polyisocyanate are used in the equivalent weight ratio of 11:1, the resultant reaction products will contain predominantly ureido compounds having amino and isocyano terminal radicals; when the :reaction mixture contains an excess of the polyamine, the .resultant reaction products will contain ureido compounds the terminal groups of which are predominantlyamino radicalls, .and whenthe viteactionmixture contains an :excess 10 10f" the pol-yisocyanate, reaction products containing ureido compounds having predominantly lSOCYfiIIDw-tfil'fillll'tll groups will be obtained.

When the polyamine is a diamine and the polyisocyanate is a diisocyanate the resultant polyureido compounds are linear. However, if one or more of the reactants is a polyamine greater than a diamine, for example, a

f triamine, such as l,3,5-triaminobenzene,'or the polyisocyanate is greater than a diisocyanate, for example, a -triisocyanate, such as, 1,3,5-benzenetriisocyanate, crossadded, some of the terminal free amines are blocked and transformed to phenyl ureido groups.

Examples of suitable polyisocyanates which can be employed in accordance herewith are tolylene diisocyanate, p,p'-diisocyanate biphenyl, 1,4-diisocyanato-ben zene, p,p'-diisocyanato-diphenylmethane, 1,6-diisocyanato hexane, 1,12-diisocyanato dodecane, 1,3,5-benzene triisocyanate, naphthylenediisocyanate, bitolylene diisocyanate, tris-p-isocyanatophenyl-methane.

Examples of suitable polyamines are benzidine, p-phenylene-diamine, o-phenylenediamine, m-phenylenediamine,

o-tolidine, triamino-benzene, 1,6-diaminohexane, 1,10-diaminodecane,

1,3-diaminopropane, dialkylenetriamine, trialkylenetetramine, ethylenediamine, xylylenediamine, tolylenediamine, dimethyl-p-phenylenediamine, etc.

Polyureido compounds of the type hereindescribed can be prepared by the reaction of water on a polyisocyanate in accordance with the probable reaction as illustrated by the following equations:

where the R represents organic radicals as above defined.

(While the reaction of the polyamine and the polyisocyanate in a mole ratio of 1:1 will give ureido compounds having aminoand isocyano-terminal radicals, in the above preparation wherein the polyamine is first obtained by the hydrolysis of the polyisocyanate, excess water present as indicated for the last reaction, hydrolyzes the isocyanoterminal radical of the final product to an amino-radical.)

The above reaction is illustrated by the following specific example using bitolylene diisocyanate:

I (oTolldine) a polymer such as The general structural formulae of illustrative ureido compounds of the type herein described are:

wherein Ar represents a phenylene radical, Ar represents a biphenylene radical, R represents a (CH alkylene radical, R represents a (CH alkylene radical and R" represents (CH alkylene radical.

While the above formulae are illustrative of ureido compounds containing an aminoand an isocyano-terminal group, the present invention is not limited to such ureido compounds, but includes ureido compounds having amino-terminal groups or isocyano-terminal groups, as shown by the general formulae given above.

Oleaginous lubricant vehicles which can be thickened with the herein described polyureido compounds to form greases of the present invention can be silicone polymer oils, mineral lubricating oils, synthetic hydrocarbon lubricating oils, synthetic lubricating oilssuchaspolyalkylene glycols and their derivatives, high molecular Weight esters of dicarboxylic acids, polyfluoro derivatives of organic compounds such as the trifluorovinyl chloride polymers known as Fluorolube (made by Hooker Chemical Company) and the trifluorochloroethylene polymers,

known as Kel-F-40 (made by The M. W. Kellogg Company), and other lubricant vehicles.

The silicone polymer oils which may be employed in accordance with the present invention are those falling substantially within the lubricating oil viscosity range. In general, such oils have the following unit structure:

wherein Rand R represent substituted or unsubstituted alkyl, aryl, alkylaryl, arylalkyl or cycloalkyl radicals. Such compounds may be produced by well-known methods, e. g. the hydrolysis or dialkyldichlorosilanes or dialkyldiethoxysilanes with a suitable chain stopper, e. g. a trisubstituted mono-chlorosilane. For purposes of the present invention, those polymers which are high boiling liquids within the lubricating oil viscosity range are suitable, these generally possessing a viscosity at F. which is within the range of from about 25 to about 3500 S. S. U. It is preferred, for purposes hereof, to employ such oils as have a viscosity at 100 F. of from aboutlOO S. S. U. to about 1250 S. S. U. Such products are generally colorless and inert, have a very low volatility and undergo relatively slight change in viscosity for a given change in temperature. Relatively common oils of this type are dirnethylsilicone polymer, phenylmethylsilicone polymer, chlorophenylmethylsilicone polymer, etc., it being preferred to employ either the phenylmethylsilicone or the chlorophenylmethylsilicone polymer in accordance herewith. Methods .of preparing such compounds are 5 taught in numerous patents, e. g. U. S. 2,410,346,11. S 2,456,496, and in the literature such as Chemistry of the Silicones, by Rochow, page 61, et seq. A particularly desirable phenylmethylsilicone polymer for use in accordance with the present invention is Dow-Corning 550 Silicone Fluid, a product of Dow-Corning, Inc, which has a Saybolt Universal viscosity at 100 F. of about300 to about 400 seconds. Another suitable silicone polymer is a chlorophenylmethylsilicone marketed as GE 81406 by General Electric Company.

Other oleaginous vehicles which may be employed herewith are, for example, mineral oils in the lubricating oil viscosity range, i. e. from about 50 S. S. U. at 100 F. to about 300 S. S. U. at 210 F; These mineral oils are preferably solvent extracted, to substantially remove the low V. I. constituents, e. g. aromatics, with phenol, furfural, B,B'-dichlorodiethylether (Chlorex), liquid S nitrobenzene, etc. Synthetic lubricating oils resulting from polymerization of unsaturated hydrocarbons or other oleaginous materials within the lubricating oil viscosity range such as high molecular weight polyoxyalkylene compounds such as polyalkylene glycols and esters thereof, aliphatic diesters of dicarboxylic acids such as the butyl, hexyl, 2-ethylhexyl, decyl, lauryl, etc., esters of sebacic acid, adipic acid, azeleic acid, etc., may be thickened by the ureido compounds of the present invention to produce excellent greases. Polyfiuoro derivatives of organic compounds, particularly hydrocarbons and dibasic acid esters of H(CF ),,CH OH, in the lubricating oil viscosity range have shown excellent promise when thickened with compounds of the present invention.

Greases of the present invention may be produced by one of the following methods:

(1) The thickener may be prepared apart from and then admixed with the lubricant vehicle and milled in a colloid mill, 3-roll mill, etc.

(2) The thickener may be formed in situ in the oil by introducing the reactants and the desired amount of lubricant vehicle, heating for a relatively short time, e. g. from about five minutes to an hour to complete the reaction, and then cooling and milling the mixture.

(3) As a slight modification of method 2 above, a solvent such as chloroform, ethyl acetate, dioxane, 2-butanone, benzene, etc., may be employed as a diluent and mutual solvent for the reactants. The solvent is then evaporated and the grease is milled, etc., substantially as set forth. Co-pending Swakon and Brannen application for Letters Patent Serial Number 392,996, filed November 18, 1953, now U. S. 2,710,841, is directed to the preparation of substituted urea thickened greases generally by the in situ technique.

(4) As a step in any of the above three methods, it has been found that improved properties may be imparted to the grease by heat-treating the grease mixture, i. e. subjecting the same to an elevated temperature for at least about half an hour and preferably longer, e. g. from about 1 to 20 hours. Prolonged heating at such temperature may evaporate a portion of the lubricant vehicle; this loss should be replaced and then the mixture should be milled. The temperature to which the mixture may be heated will, of course, depend upon the particular lubricant vehicle employed. Thus, a silicone polymer oil may be heated to a temperature of about 450 F. but mineral oils, diesters, and other synthetic oils may be heated from about 200 to 400.

The present invention is illustrated by the following examples:

Example I One-hundredth of mole (1.84 grams) of benzidine, dissolved in ethyl acetate, was added to one-hundredth of mole (2.5 grams) of p,p'-diisocyanato-diphenylmethane in a solvent-extracted SAE 40 petroleum oil (17.4 grams). An immediate reaction occurred which resulted in the thickening of the mixture. The mix was heated and the 6 .se i'sm .remq s y d sti lat qs- Afte sth salvea was remo e t e re ultant p odust as hea ed to 30.0 o ed n an o n t 3 .F- for two hours, co led-t about 80 F., and then milled. The finished grease conm n 2 o P d mi antly t e po y-ure do ompo was a m t ho -fib ed p oduct h ng a micropen t a io 1 o 16.8-

Example II A polyureido thickened solvent extracted SAE 40 petroleum oil was prepared as in Example I, usingonehu d h 1.1101e 1 -08 m f p-p l n d sm ss i P a of h b n i Th nished r asep dus ,-sentaining of the polyureido compound was smooth and short-fibred and had a micropenetration of .60.

Example III A mixture of one-fiftiethmole (5.0 grams) o f p-p'- .diisocyanatodiphenylmethane in a solvent extracted SAE 40 petroleum oil and one-hundredth mole each of benzidine (1.84 grams) andp-phenylenediamine (1.08 grams) dissolved in ethyl acetate was heated at 300 F. for about fifteen minutes and the solvent removed by evaporation. The solvent-free product was then stored at 300 F. for two hours, cooled to 80 F., and then milled. Th finished grease product containing 20% of the polyureido compound was smooth and short-fibred and had a micro penetrationof 78.

The stability of polyureido thickened greases is illustrated by the following micropenetration data on the greases after being held at 300 F. for one, two, and three days.

Mlcropenetratton (after milling) r r a A Initial One Two Three Day Days Days Grease of Example I 168 148 177 15s Grease of Example 11... so 87 us 154 Grease of Example III 78 54 58 00 3x5115 811, G., Finn, .T., and Harrington, .T., Ind. Eng. Chem., Anal. Ed., 11, 108 (1939).

Example I V An intimate, mixture of DC 550 Silicone Fluid and dry powder from the reaction of bitolylene diisocyanate and water was passed over a three-roll mill. The resulting product is a bright, smooth paste. .Penetration data on application Ser. No. 318.321 (supra) at 450 F. and 10,000 R. P. M. ran 211 and 344 hours.

Example V Grease made by method used in Example IV except diisooctylazelate used in place of DC 550 Silicone Fluid.

The resulting grease .containing 12.5% thickener had a At-size cone penetration of 63.

Example VI using a solvent-extracted SAE 40 grade petroleum oil had a At-size penetration of 72 with 15% concentration of thickener.

1 Kaufman, G., Finn w. 1., and Harrington, R. J., Ind. Eng.

75 Chem, Anal. Ed, 11, 108 (1939 Grease made by the method used in Example IV and I Greases of the present invention can contain well known additives such as anti-oxidants, oiliness agents, extreme pressure agents, anti-foam agents, etc. without departing from the scope of the invention.

Although the present invention has been described with reference to specific preferred embodiments thereof, the invention is not to be considered as. limited thereto, but includes within its scope such modifications and variations as come within the spirit of the appended claims.

I claim:

1. A lubricant grease comprising a lubricant vehicle thickened with from about 2% to about 50%, by weight, of at least one ureido compound having the general formula wherein Z and Z are terminal reactive radicals selected from the group consisting of NH; and -'NCO radicals and mixtures thereof, x is an integer to 5, and R, R, and R" are organic radicals selected from the group consisting of an alkylene radical, a substituted alkylene radical, an arylene radical, a substituted arylene radical and mixtures thereof, said alkylene radical and substituted alkylene radical having 1 to about 30 carbon atoms, and said arylene and substituted arylene radical having no more than 14 cyclic carbon atoms.

2. A lubricant grease as described in claim 1 in which the lubricant is a hydrocarbon lubricating oil.

3. A lubricant grease as described in claim 1 in which the lubricant vehicle is a silicone polymer oil in the lubricating oil viscosity range.

4. A lubricant grease as described in claim 1 in which the lubricant vehicle is an acyclic ester of an aliphatic dicarboxylic acid.

5. A lubricant grease as described in claim 1 in which the lubricant vehicle is a polyfluoro-compound in the lubricating oil viscosity range.

6. A lubricant grease as described in claim 1 in which R, R, and R" are organic radicals selected from the group consisting of an arylene radical, a substituted arylene radical, and mixtures thereof, said arylene and substituted arylene radicals having not more than l4 c,yclic carbon atoms.

7. A lubricant grease as described in claim 1 in which R, R, and R are organic radicals selected from the group consisting of an alkylene radical, a substituted alkylene radical and mixtures thereof, said alkylene and substituted alkylene radicals containing from 1 to about 30 carbon atoms.

8. A lubricant grease comprising a lubricant vehicle thickened with from about 2% to about 50%, by weight, of at least one polyureido compound having the general formula 'stituted arylene radical having no more than 14 cyclic carbon atoms.

9. A lubricant grease comprising a lubricant vehicle thickened with from about 5% to about 40%, by weight, of a polyureido compound having the formula in which R is a phenylene radical.

10. A lubricant grease comprising a lubricant vehicle thickened with from about 5% to about 40%, by weight, of a polyureido compound having the formula in which R is a bitolylene radical.

11. A lubricant grease comprising a lubricant vehicle thickened with from about 5% to about 40%, by weight, of a polyureido compound having the formula in which R is a phenylene radical and R' is a bipheylene radical.

12. A lubricant grease comprising a lubricant vehicle thickened with from about 5% to about 40%, by weight, of a polyureido compound having the formula:

H N--(CI-I NH-CONH( CH NHCONH(CH NCO 13. A lubricant grease comprising a lubricant vehicle thickened with from about 5% to about 40%, by weight, of a polyureido compound having the formula in which Ar represents a phenylene radical.

References Cited in the file of this patent UNITED STATES PATENTS 2,292,443 Hanford Aug. 11, 1942 2,710,839 Swakon et a1 June 14, 1955 2,710,840 Swakon et a1 June 14, 1955 2,710,841 Swakon et a1 June l4, 1955 U. 5. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No, 2,832,739 Edward A, Swakon It is hereby certified that error appears .in the printed specification of the above numbered patent requiring correction and that the said Letters April 29, 1958 Patent should read as corrected below.

Column 2, line 25, for that portion of the formula reading "(NH-CO-NH-R read (NH-CO-NH-R"-) column 8, line 27, extreme left-hand portion of the formula, for "H H-" read H N-'- Signed and sealed this let day of July 1958.

(SEAL) Attest:

KARL H AXLINE ROBERT C. WATSON Attesting Officer Conmissioner of Patents

Claims (1)

1. A LUBRICANT GREASE COMPRISING A LUBRICANT VEHICLE THICKENED WITH FROM ABOUT 2% TO ABOUT 50%, BY WEIGHT OF AT LEASR ONE UREIDO COMPOUND HAVING THE GEANRAL FORMULA