US3723317A - Lubricant greases - Google Patents

Abstract

LUBRICATING GREASES COMPRISING A FLUORINATED POLYETHER BASE OIL, FROM ABOUT 4 TO ABOUT 50% BY WEIGHT OF A POLYMER OF TETRAFLUOROETHYLENE AND FROM ABOUT 0.2% TO 15% BY WEIGHT OF A 1,3,5-TRIAZINE SAID TRIAZINE HAVING AS SUBSTITUENTS AMINO, HYDROXY AND/OR MELAMINO GROUPS.

Description

United States Patent 3,723,317 LUBRICANT GREASES Harris Ellsworth Ulery, Newark, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del. No Drawing. Filed May 25, 1970, Ser. No. 40,347 Int. Cl. Cm 7/30 US. Cl. 252-51.5 R 16 Claims ABSTRACT OF THE DISCLOSURE Lubricating greases comprising a fiuorinated polyether base oil, from about 4 to about 50% by weight of a polymer of tetrafinoroethylene and from about 0.2% to by weight of a 1,3,5-triazine said triazine having as substituents amino, hydroxy and/ or melamino groups.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to novel lubricating greases comprising a fluorinated base oil, a polymer of tetrafluoroethylene and a triazine or a mixture of triazines, said greases being useful as lubricants over a broad range of temperatures, preventing corrosion even at high temperatures while at the same time being resistant to wash-out.

(2) Description of the prior art Skehan in US. 3,505,229 discloses greases containing a fiuorinated polyether base oil thickened with a polymer of tetrafiuoroethylene. It is however recognized in the art that constant improvement in greases of this type is necessary to meet the changing needs in such fields as for example aero-space wherein extreme pressure lubricating properties and ability to protect aero-space structural metals, particularly titanium alloys, against corrosion at high temperatures is of primary importance.

In Air Force Materials Laboratory Report, AFML-TF- 66-107 (April 1966) I. B. Christian and K. R. Bunting disclose attempting to prepare greases by thickening per fluorinated polymeric fluids with 2,4-diamino-6-hydroxy- 1,3,5-triazine, aryl substituted ureas, clays, perfluorinated ethylenepropylene copolymer or polytetrafluoroethylene. Only the triazine and the perfiuorinated ethylene-propylene copolymer would thicken the perfluorinated polymeric fluids into greases. Triazine thickened greases of this type are however prone to thickener wash-out by various solvents and aircraft and rocket fuels.

The novel lubricating greases of the present invention possesses the necessary properties of lubricating at high, low and intermediate temperatures, nonreactivity with metals, and resistance to air oxidation required in the aero-space field and at the same time manifest resistance to wash-out by various solvents and fuels, thus overcoming the extant problems of the triazine thickened greases.

SUMMARY OF THE INVENTION The present invention is directed to lubricating greases comprising a fluorinated oil, a polymer of tetrafiuoroethylene and a triazine or mixture of triaznies. The tetrafluoroethylene polymer which will be present in an amount of from about 4% to about 50% by weight of the total grease must have a molecular weight of from about 2000 to about 4,000,000 and containing at least 85% by weight of --CF CF units. The triazine or Patented Mar. 27, 1973 ice 0.2% to about 15% by weight of the total grease. The triazine or triazine mixture will have the structure A. ne

wherein R, R and R" are the same or different and are amino, hydroxy or melamino groups, the melamino group having the formula DESCRIPTION OF THE INVENTION wherein --C F O is -CF O--, -CF(CF )O-, -CF2CF20-, CF3 O1 -CF CF(CF )O- R, is a perfluoroalkylene group having from 1-6 carbon atoms, R, is the same or a different perfiuoroalkylene group having from 1-6 carbon atoms, X is H, -F or CF O, Y is H or F and may be the same as or different from X when X is H or F, m is an integer of from 13, n is an integer designating the number of (C -F O) groups present in the molecule wherein m is 3, p is an integer designating the number of --(C F O)- groups present in the molecule wherein m is 1 or 2 and the sum of n+p is an integer of from 0 to about 100 and R", is a 1,2-perfiuoroalkylene group having from 2-4 carbon atoms.

Representative of the structure (a) oils are:

HCF2O[CF(CF3 CF2O]11CF2H 0F.0[0 F2CF(CFB)O]nC F111 01*.010130 F(CF3)O] CFOCF1O[CFZCF(CF3)O]11CF2H CFsO[CF2CF(CFa)O]sC F2OCF=H 0 F30 c F10[C F10 F(C mono F211 CFaOCF(CFa)O[C F,CF(OF3)O].,CFH CF3O[CF1CF(CF3)O]..C F(C FalH CF30 F2CF2O[CF(CF:)CF2OL1C F(C F011 CF3CF2C FzO[CF(CFs)CF2O] C F101; CF;C F10 FzO[CF(C F3)CFIO]n(C F20 F2050 F10 F;

CFO[CF(CF3)CF2O111GF(CF3)H and 0 F F20 Ft CFO[C F(CFa)C FzOhCFzCF:

o F Representative of the structure (b) oils, which are polymixture of triazines is present in an amount of from about ethers, is:

Those polyethers having perfiuoroalkyl end groups, i.e., without 'C-H bonds, are usually preferred for the greases of this invention.

The more preferred base oils within the class described above have (1) a maximum volatility of 50% by weight at 204.4 C., as determined by Federal Test Method FTMS-791, Method 351;

(2) a maximum pour point of C., as determined by ASTM-D-97; and

(3) capability of forming a grease when blended under grease forming conditions with a thickening quantity of a polymer of tetrafluoroethylene having at least 85% by weight CF CF units and a molecular weight of from about 2000 to about 4,000,000.

The oils utilized in the preferred greases of this invention should have a maximum volatility of 50% at 204.4 C. and a maximum pour point of 10 C. and it may be necessary to fractionate some of the oils given above to provide them with the preferred volatility and pour point. Within this classification it has been found that the fluorinated polyether oils having molecular weights of 3000 to 13000 are preferable. Of course, the polymerization methods used in preparing the oils give mixtures of products so that the molecular weights are an average. Although a pure product having a specific molecular weight can be used, mixtures of products are equally useful if the variation in molecular weight is not too large. Usually, the most volatile lower molecular weight materials are removed from oils before use.

Oils having volatilities greater than 50% at 204.4 C. while not preferred, may be utilized in preparing the greases of this invention. Oils having pour points greater than 10 C. while not preferred, may also be used.

Tetrafluoroethylene polymers which comprise from about 4% to about 50% by weight of the greases of this invention are utilized as thickeners and may be selected from any polymer, copolymer or telomer containing at least 85% by weight of tetrafluoroethylene units, i.e., CF CF units, and having a molecular weight of from about 2000 to about 4,000,000. Preferably, these polymers fall into one of three classes:

(1) Tetrafluoroethylene homopolymers such as Teflon, or pyrolysis products thereof having molecular weights of from about 2000 to about 4,000,000. Such polymers are essentially 100% tetrafluoroethylene units.

(2) Tetrafluoroethylene-hexafluoropropylene copolymers containing at least 85% tetrafluoroethylene units by weight.

(3) Tetrafluoroethylene telomers of structure having molecular weights of from about 2000 to about 100,000 wherein the groups X and Y are derived from a telogen molecule, XY wherein n is an integer of from about 30 to about 1600. These tetrafluoroethylene telomers having such'a molecular weight contain more than 85% by weight tetrafluoroethylene units and normally contain more than 90% by weight tetrafluoroethylene units. Tetrafluoroethylene telomers are prepared by causing tetrafluoroethylene to polymerize in the presence of XY, the elements of XY being incorporated into the telomer. The molecule XY must be cleavable under the polymerization conditions and may vary widely. Examples of classes of telogens XY include aliphatic hydrocarbons (X=H, Y=hydrocarbon residue), aliphatic ethers containing an a-hydrogen (X=H, Y=ether residue), tertiary amines (X=H, Y=amine residue), aliphatic alcohols (X=H, Y=alcohol residue), mercaptans (X=H, Y= mercaptan residue), disulfides (X=Y=RS-), aliphatic carbonyl compounds containing a-hydr'ogen (aldehydes, ketones, diketones, keto-acids, ketonitriles, acids; X=H, Y=amide residue), aliphatic halo-hydrocarbons containin g halogen other than fluorine (X=halogen, Yzresidue). Mixtures of telogens may also be used.

Examples of useful telogens are: butane, isobutane, methylcyclohexane, 2,3-dimethylbutane, tetrahydrofuran, diethylether, dioxane, trimethylamine, triethylamine, methanol, ethanol, isopropanol, sec.-butano1, cyclohexanol, ethyl mercaptan, butyl mercaptan, dodecyl mercaptau, dimethyl disulfide, diethyl disulfide, dib-utyl disulfide acetaldehyde, propionaldehyde, butyl aldehyde, acetone, butanone, 2,4-pentanedione, ethyl acetoacetate, acetic acid, butyric acid, ethyl acetate, dimethyl formamide, dimethyl acetamide, carbon tetrachloride, chloroform, bromoform, methyl chloride, hexachloroethane, monofluorotrichloromethane, trlchlorotrifluoroethane, difluorotetrachloroethane and the like.

Relatively active telogens give lower molecular weight telomers. Relatively inactive telogens such as trichlorotrifluoroethane give higher molecular weight telomers. Ultra-high molecular weight polytetrafluoroethylene, prepared by an aqueous emulsion polymerization usually has a molecular weight in excess of 1,000,000. The tetrafluoroethylene polymers should contain at least by weight tetrafluoroethylene units. Polymers containing less than this amount of tetrafluoroethylene are likely to be either too unstable or to be otherwise unuseful in the present greases. The preferred polymers contain or more tetrafluoroethylene units.

A preferred tetrafluoroethylene telomer would be and naverages from about 500 to about 800. A telomer having this molecular weight range may be prepared, for example, at a reaction temperature of 150 C. by simultaneously introducing into a silver-lined pressure reactor, separate streams of reactants, one stream being tetrafluoroethylene and the other 1,1,2-trichloro-l,2,2- trifluoroethane containing ditert-butylperoxide. The following mole ratios would be maintained in the reactor: 0.081 mole of tetrafluoroethylene per mole of trichlorotrifluoroethane and 0.0014 mole of the peroxide per mole of trichlorotrifluoroethane. An average residence time of 1 hour for the reactants in the reactor and a pressure of 42 kg. per cm. would be maintained by suitably adjusting reactant feed and product removal rates.

Thickeners, particularly the above tetrafluoroethylenetrichlorotrifluoroethane telomer, having molecular weights in the range of 35,000 to 50,000 have more than 90% by weight CF CF units. They show a very high resistance to thermal degradation and are easily milled or homogenized into smooth, stable greases.

In general, greases are rated according to National Lubricating Grease Institute (NLGI) grade, ranging from 0 to 6. The grease grade is determined by Test Method ASTM-D-217-52T. For grade 0 classes the weight ratio of the fluorinated polyether oil to the tetrafluoroethylene polymer thickener is about :5; for grade 6 classes the ratio is about 50:50. For intermediate grade greases, the ratios range between these extremes. What should in fact be effected is that a suflicient quantity of tetrafluoroethylene polymer be employed to thicken the fluorinated oil. Since the ability of the tetrafluoroethylene polymer to thicken the oil may vary with the molecular weight of the tetrafluoroethylene polymer, it will be appreciated that the grease grade may also vary within the above polymer concentration range as one varies thickeners used.

From about 0.2% to about by weight of the greases of this invention is a triazine, or mixture of triazines,

. N N LQ R,

wherein R, R and R" are the same or different and are amino, hydroxy or melamino groups, the melamino group having the formula Representative triazine, additives are 2,4,6-triarnino- 1,3,5-triazine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2,4- diamino-G-melamino-1,3,5-triazine and 2,4,6-trimelamino- 1,3,5-triazine, the melamino group having the structure Such triazines are known in the art; many of them are commercially available or readily prepared by wellknown procedures. For example, such triazines having 1 to '3 melamino groups can be prepared by the reaction of-cyanuric chloride and 2,4,6-triamino-1,3,5-triazine followed by hydrolysis or ammonolysis of any remaining chloride substituents.

Mixtures of such triazines are included in this invention and can arise during the preparation of such triazines. For example a mixture of the above trimelaminotriazine and the diaminohydroxytriazine results when cyanuric chloride and 2,4,6-triamino-1,3,5-triazine are mixed in a 1:3 molar ratio, heated slowly to 300 C., maintained at 300 C. for 6 hours, cooled, treated with aqueous sodiumhydroxide, water washed, extracted with acetone and dried. Such a mixture is a highly suitable additive for the present greases.

' Other mixtures of triazine derivatives may also form in situ in a grease utilized at high temperatures. Thus, for example, where a triazine or a mixture of the above triazines containing amino or amino and hydroxy substituents is heated to between about 300 and about 425 C., water and/or ammonia are lost to the extent of 15 to 45% by weight of the original triazine or triazine mixture and a mixture of condensed triazines results. Such a mixture can contain such structure as heptazine derivatives, e.g.,

Useful concentrations of the above triazines in the greases of the invention range up to about 15 by weight of the total grease. What is required is that there be sulficient triazine present to provide resistance to reaction with metals and resistance to air oxidation, for example, retardation of titanium alloy stress corrosion at temperatures above 250 C. Triazine concentrations between about 0.5 and about 15% by weight of the total grease are preferred. Depending on the end use for which the grease is intended, very highly practical triazine concentrations are between 1 and 10% by Weight of the total grease.

To further reduce the possibility of triazine washout from the present greases, it is usually preferable to employ the triazine in concentrations such that the amount of triazine in the grease does not exceed the amount, by weight, of the tetrafluoroethylene polymer thickener.

Preferred greases of this invention comprise a perfiuorinated polyether base oil having the structure wherein n is an integer from about 18 to about 80, a tetrafluoroethylene polymer thickener having at least by weight of -CF CF units and a 2,4-diamino-6-hydroxy-l,3,5-triazine or a 2,4,6-triamino-1,3,5-triazine, the weight ratios of the base oil to tetrafiuoroethylene polymer thickener being from :5 to 50:50, the base oil having a molecular weight of 3,000 to 13,000, the tetrafluoroethylene thickener having a molecular Weight of from 35,000 to 50,000 and the amount of triazine present being from about 0.5 to about 15% by weight of the total grease. Particularly preferred greases falling within this range are prepared from a polyether base oil having the structure CF CF CF OIJCF(CF )CF O],,CF CF wherein n is an integer from about 22 to about 35, and having a molecular weight of 4000 to 6000, a tetrafluoroethylenetrichlorotrifluoroethane telomer thickener having a molecular weight of from 35,000 to 50,000 and 2,4-diamino- 6-hyclroxy-1,3,5-triazine. In this molecular weight range, the oil has a very low pour point, usually below 20 C. and a volatility of, at most, 1% to 2% at 204.4" C. The diaminohydroxytriazine has a relatively high ressitance to thermal degradation and is very easily milled into a grease.

The greases of the present invention may be prepared by mixing the solid tetrafiuoroethylene polymer, the triazine and the base oil by any convenient means. The polymers and the triazines should be finely divided in the grease. This is usually accomplished by preparing the grease in an ink mill, grease mill, homogenizer or the like which subdivides the solid particles during the process. When the tetrafluoroethylene polymer is obtained as a dispersion in a volatile medium such as 1,1,2-trichloro-1,2,2-trifluoroethane, it is often convenient to combine such dispersion with the oil and the triazine and then remove the volatile medium by vacuum stripping or other similar means for removing such materials. Blending order is not critical; triazines can be added to greases already prepared from the oils and the tetrafiuoroethylene polymers. Further milling then disperses the triazine. Alternatively, a binary composition comprising the tetrafluoroethylene polymer solids and the triazines may be prepared and then added to the base oil again by any convenient means. Effective binary compositions which would be useful for thickening a fluorinated base oil to form a grease and which would impart to said grease improved lubricant and anti-corrosion properties and resistance to triazine wash-out would comprise from about 1 part of one or more of the previously described triazines per 250 parts of tetrafiuoroethylene polymer as defined to about 1 part of the triazine per 1 part of the tetrafiuoroethylene polymer. This would be from about 0.4% by weight of the triazine and about 99.6% by weight of the tetrafluoroethylene polymer to about 50% by weight of each. Such binary compositions may be prepared by mixing appropriate quantities of the dry, particulate ingredients. Alternatively, the triazine, preferably finely divided, maybe added to a tetrafluoroethylene suspension in a volatile medium as described above.

The greases of this invention provide a unique and unexpected combination of properties including lubricity at both high and low temperatures, nonreactivity with metals, resistance to air oxidation, and to wash-out by fuels and various solvents. These greases also have advantageous extreme pressure lubricating properties. This combination of properties makes the greases of this invention useful under conditions which exist when used in jet planes, for use in aircraft having maximum speeds in excess of speed of sound, missile systems and other similar situations where resistance to high temperatures, oxidizing conditions or Wash-out from contact with rocket fuels or jet fuels is required. They are useful for lubrieating fuel valves, ball bearings, roller bearings, needle bearings and the like where oil lubrication of such equipment is not possible due to their location. These greases can, of course, be used under conditions where presently available greases are useful but have the added advantage of being useful in situations where no other greases will survive. Unlike art-known greases which contain triazine but not tetrafluoroethylene polymer thickner, these greases will not wash out when exposed to water or various fuels and unlike the art-known greases containing tetrafiuoroethylene polymer thickeners but not triazine additives, the greases of the present invention will afford satisfactory corrosion pnotection at high temperatures particularly with respect to titanium alloys.

EXAMPLES The following examples are intended to be merely i1- lustrative of the invention and not in limitation thereof. Unless otherwise indicated, all quantities are by weight.

Example 1 A base grease was prepared by first blending 85.2 parts of an oil having the structure and wherein n averages about 34, an average molecular weight of about 6000, a pour point of 34 C. and a volatility of 0.1% by weight at 204.4" C., and 14.8 parts of a tetrafiuoroethylene 1,1,2 trichloro-1,2,2-trifiuoroethane telomer having an average molecular weight of 35,000 to 50,000, the telomer suspended in trichlorotrifluoroethane. The resultant 3-component suspension was then subjected to homogenization and vacuum stripping to remove the trichlorotrifluoroethane and to produce a smooth, buttery, white, NLGI Grade 2 grease.

Into 247.5 parts of this base grease were blended 2.5 parts of 2,4-diamino-6-hydroxy-1,3,5-triazine powder having a maximum particle size of 149g. The blend was homogenized by six passes through a 3-roller ink mill with 38 11. roller clearances. A smooth NLGI Grade 2 grease resulted.

Example 2 A second grease containing by weight of 2,4- diamino-6-hydroxy-1,3,5-triazine was prepared substantially as in Example 1 from a base grease containing of the fiuorotelomer solid in an oil having the same structure as the oil of Example 1 said oil having an average molecular weight of about 5600, a volatility of 0.7% by weight at 204.4 C. and a pour point of 37 C. A smooth, NLGI Grade 2 grease resulted.

Example 3 A third grease was prepared substantially as in Example 2 except that 10 weight percent of 2,4,6-triamino- 1,3,5-triazine was substituted for the 10 weight percent of the 2,4-diamino-6hydroxy-1,3,5-triazine. A third smooth, NLGI Grade 2 grease was obtained.

Table l following summarizes the ASTM Penetrations of the base greases and the three triazine-containing NLGI Grade 2 greases prepared therefrom.

lized are known thickeners for fluorinated oils, they had no significant thickening effect on the base grease.

Greases having consistencies other than NLGI Grade 2 can be prepared as in the same manner as above, by varying the oil-thickener ratio. Lighter greases may be prepared by reducing the fiuorotelomer solids content to as low as about 4% by weight. Heavier greases may be prepared by increasing the fiuorotelomer thickener content up to about 50% by weight. Lighter base greases may also be prepared by utilizing a fixed quantity of the thickener and a less viscous polyfiuorinated polyether oil, so long as the oil has a volatility no greater than 50% by weight at 204.4 C.

Example 4' A fibrous, NLGI Grade 1 grease was prepared by repeatedly passing a suspension of 12.1 parts of a polytetrafiuoroethylene molding powder (molecular weight 1,000,000), 85.0 parts of the oil of Example 1 and 2.9 parts of 2,4-diamino-6-hydroxy-1,3,5-triazine through an ink mill with 38g roller clearances.

A comparative grease not within the scope of the present invention, was prepared as follows:

Comparative grease: An oil as in Example 1 having an average molecular weight of about 4500, a volatility of 0.2% by weight at 204.4? C. and a pour point of 34 -C. and 2,4-diamino-6-hydroxy-1,3,5-triazine were blended to provide an unmilled grease containing 23% by weight of the triazine. A smooth, NLGI Grade 2 grease was prepared from the unmilled grease by repeated passes through an ink mill having 38 roller clearances. The worker ASTM Penetration is 270 mm./ 10 at 25 C.

Y The following examples illustrate the superior .properties of the grease of this invention. 1

Example 5 The effect of various solvents on the above greases was determined by first manually coating clean, dry microscope slides with 2 to 4 mm. of the particular grease being tested and then immersing the coated slides at about 25 C. in separate beakers containing acetone, benzene and a 50/50 weight mixture of absolute methanol and 1,2- diaminopropane. The base greases of Examples 1 and 2 and a grease Within the scope of this invention prepared as in Example 1 except that it contained 9% by weight of diaminohydroxytriazine remain unalfected by these solvents for at least 24 hours while the- Comparative grease deteriorated, precipitating its solids in less than an hour. The above solvents were chosen to represent materials with which the greases would most likely come into contact during use. That the greases are extremely resistant to triazine wash-out is emphasized in that even relatively highly polar solvents such as benzene and acetone have practically no effect on the relatively polar triazine.

It is therefore clearly seen that while the greases containing triazines and no flouorotelomer rapidly deteriorated and the triazines contained'therein washed out, the presence of a virtually inert particular fiuorotelomer in the greases of the -presentinvention unexpectedly prevented the washing-out of the triazines contained therein.

Example ,6

.. Longitudinal Transverse Yieldstrength,kg./cm." 11,000 10,300 Tensile strength, kgJcrn. 11, so? 12, 208

Elongation, percent in 50.8 mm

Flat strips 9.5 by 114.3 mm. were cut longitudinally ffom' the sheet. The endsof eaoh strip were heat in the same direction to an angleof 20 relative to the horizontal portion of'the-strip; Thebent ends were fiat and measured 25.4 mm. from the bend. Two such strips were bolted together at the ends with steel bolts to form an eyeshaped, symmetrical, prestressed bow.

The corrosion tests were conducted by first packing the interior of the test bows with the grease and generously coating the external portion of the bows with the grease. The packed, coated bows were then stored in air at 260 C. At intervals, the bows were cooled, freed of grease, examined for failure and, if unfailed, repacked, recoated and returned-to the 260 C. oven. Failure of a bow was indicated by visible stress cracking, weakening as shown by deformation of bow symmetry or actual breaking of a bow. Table H summarizes tests results.

TABLE II Hours to fail- Grease tested: ure at 260 C.

Base grease prepared. as in Example 1 (no triazine) 2931181 Example 1 NLGI grease (1.0% triazine) 2 283 Example 2 NLGI grease tr.iav zine) 1905 4 tests. Testing was stopped after 2283..-,hours with no apparent Example 7.

ASTM method D-2266-64T, the so-called Four-Ball Method, was employed to evaluate greases. Theball bearings were of AISI C-52100 steel. Test conditions were as follows: 7

Load: 50 kg.

Temperature: 260 C. Speed of rotation: 600 rpm. Test duration: 1 hour The test was evaluated by measuring the post-test wearscar diameter on each of the three stationary ball bearings and averaging the three scar diameters. The test results are summarized in Table III.

TABLE III p v Average wear-scar 1 r I diameter, mm.

Base grease prepared asin Example 1 (no triazine) 10 Example 2 NLGI Grade 2 grease 10% triazine) 0.52 Example 3 NLGI Grade 2 grease (10% triazine) 0.51

It is clear from these results that the greases of the present invention are superior in wear resistance to the base grease which did not contain triazine.

The foregoing detailed description has been given for clarity of understanding only and no unnecesaiy limitations are to be understood therefrom. The invention is not limited to exact details shown and described for obvious modifications will occur to one skilled in the art. Greases having similar properties with respect to high-temperature titanium alloy corrosion, extreme pressure lubricity and resistance to triazine wash-out can also be prepared from other fiuorinated polyether oils having the previously defined volatility and pour point limits, a polymer of tetrafiuoroethylene having a minimum molecular weight of at least 2000 and at least by weight of CF CF units and a triazine as defined above.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A grease comprising:

(a) fiuorinated polyether base oil,

(b) from about 4 percent to about 50 percent by weight of a polymer of tetrafluoroethylene having a molecular weight of from 2000 to about 4,000,000 and containing at least 85 percent by Weight of CF CF units, and

(c) from about 0.2 percent to about 15 percent by weight of a triazine or a mixture of triazines having the structure A. we

wherein R, R and R" are the same or diflierent and are amino, hydroxy or melamino groups, the melamino group having the formula 2. A grease according to claim 1 wherein the fluorinated oil (a) is XR;O(C F O) R';Y or

wherein -C F O- is CF O, CF (FC )O, CF CF O--, CF(CF CF O or --CF CF(CF )O-, R; is a perfiuoroalkylene group having from 1-6 carbon atoms, R, is the same or a different perfiuoroalkylene group having from 1-6 carbon atoms, X is H, F or CF O, Y is H or F and may be the same as or different from X when X is H or F, m is an integer of from 1-3, n is an integer designating the number of (C F O)-- groups present in the molecule wherein m is 3, p is an integer designating the number of (C F O)-- groups present in the molecule wherein m is l or 2 and the sum of n+p is an integer of from 0 to about and R" is a rl,2-perfiuoroalkylene group having from 2-4 carbon atoms.

3. A grease according to claim 1 wherein the tetrafiuoroethylene polymer of (b) is (1) a tetrafiuoroethylene homopolymer or pyrolysis product thereof having a molecular weight of from 2000 to about 4,000,000,

(2) a tetrafluoroethylene-hexafiuoropropylene copoly mer containing at least 85 percent tetrafluoroethylene units by weight, or

(3) a tetrafluoroethylene telomer of the structure X(CF CF Y having molecular Weights of from about 2000 to about 100,000 wherein the groups X and Y are derived from a telogen molecule XY and wherein n is an integer of from about 30 to about 1600.

4. A grease according to claim 3 wherein the tetratluoroethylene polymer is a tetrafluoroethylene homopolymer or pyrolysis product thereof having a molecular weight of from 2000 to about 4,000,000.

5. A grease according to claim 3 wherein the tetrafluoroethylene polymer is a tetrafiuoroethylenehexafluoropropylene copolymer containing at least 85 percent tetratluoroethylene units by weight.

6. A grease according to claim 3 wherein the tetrafluoroethylene polymer is a tetrafluoroethylene telomer of the structure X(CF CF ),,Y having a molecular weight of from about 2000 to about 100,000 wherein the groups X and Y are derived from a telogen molecule X-Y and wherein n is an integer of from about 30 to about 1600.

7. A grease according to claim 6 wherein the tetrafiuoroethylene polymer is C C1 F (CF CF Cl and wherein C Cl -F is CF (Cl)CF(Cl)- or CF (C1) GP;-

and n averages from about 500 to about 800.

8. A grease according to claim 1 wherein the triazine or mixture of triazines of (c) is 2,4,6-triamino-1,3,5-triazine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2,4-diamino- 6-melamino-1,3,5-triazine or 2,4,6-trimelamino-1,3,5-triazine, the melamino group having the structure:

HzN-QLNH:

9. A grease according to claim 1 comprising a fluorinated polyether oil having the structure wherein n is an integer from about 18 to about 80, a tetrafiuoroethylene polymer containing at least 90% by weight of CF CF units and 2,4 diamino-6-hydroxy-1,3,5- triazine or a 2,4,6-triamino-1,3,5-triazine.

10. A grease according to claim 9 wherein the weight ratios of the fluorinated polyether oil to tetrafiuoroethylene polymer is from 95:5 to 50:50 said oil having a molecular weight of 3,000 to 13,000, and said tetrailuoroethylene polymer having a molecular weight of from 35,000 to 50,000 and the amount of triazine present being from about 0.5 to about 15% by Weight of the total grease.

11. A grease according to claim 1 comprising a fluorinated polyether oil having the structure wherein n is an integer from about 22 to about 35, and

13. A grease according to claim 1 comprising about 77% by weight of a fluorinated polyether. oil having the structure CF3CF3CF20[CF(CF3)CF20] CFgCFa wherein n averages about 34, about 13% by weight of a tetrafluoroethylene-l,1,2-trichloro-1,2,2-trifluoroethane telomer and about 10% by weight of 2,4-diamino-6-hydroxy-1,3,5- triazine.

14. A grease accordingto claiml comprising about 77% by weight'of a fluorinated polyether oil having the structure CF CF CF 0 [CF(CF ')CF 0] CF CF wherein n averages about 34, about 13% by weight of a tetrafluoroethylene-1,l,2trichloro-1,2,2 trifluoroethane telo; mer and about 10% by weight of 2,4,6-triamino-1,3,5- triazine. 1

15. A binary composition for thickening a fluorinated polyether base oil which binary composition comprises a triazine or mixture of triazines having the structure wherein R, R' and R" are the same or different and are amino, hydroxy or melamino groups, the melamino group having the formula wherein R, R and R" are the same or diiierent and are amino, hydroxy or melamino groups, the melamino group having the formula wherein the weight percent relationship of triazine to tetra'fluoroethylene polymer is 'from about 0.4% by weight of triazine andabout 99.6% by weight of tetrafluoroethylenepolymerto frornabout 50% by weight triazine to 50% byweight ofittrafiuoroethylene polymer.

(Reference s on following page) 13 14 References Cited Air Force Material Laboratory Report, AFML-TF-6'6- UNITED STATES PATENTS 107 (API111966LPP- 3,505,229 4/1970 Skehan 252/51.5 R DANIEL WYMAN, Primary Examiner 3,525,690 8/ 1970 Christian 25251.5 R 5 L VAUGHN Assistant Examiner OTHER REFERENCES Greases Based on Perfluoro Polymeric Fluids-A New Class of Greases for Aerospace Use by Christian et al. in 2525 1, 53, 392