GREASE COMPOSITION

This invention relates to improved grease composition.

In one aspect, the invention relates to novel heat-stable greases which contain poly(p-oxybenzoyl) as a thickener.

Certain grease compositions, generally designated 6 j j t t i 1- i, bearing greases, are designed to operate at high mechanical loading. In add, ion to being stable under these mechanical stresses, the grease composition must be thermally stable. Alo it is desirable that grease composi- ,, mP ? , tions retain their physical properties even after exposure v e e to radiation.

Conventional greases are made by adding soaps such as lithium stearate 01 -finely divided solid filler matenas, such as silica or bentonite to a lubricating oil vehicle m an amount sufficient to form an intimate mixture of 3 eftrs of tnmethylol propane and pentaerythritol; phosbutter-like consistency. Generally, the particulate fillers another consideration in the selection of a grease filler i the pce ofhe present invention wherein p-oxybenzoyl polymer is utilized as a grease thickener, one obtains a lubricating composition which is stable under heavy loadings at high temperature. Also the grease compositions of the invention are highly inert and resist It isPanother object of I, invention to provide heatstable, radiation-resistant grease compositions.

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a grease composition comprising an intimate mixture of t mtur t ttrconSc f f the tease compositions of the invention is Poly(p-oxy-

w">-y Wi tSnSsr consistmg essen- b-r T cor T Nira Falls ?-Y- re poflymf The lubricatini oil vehicle can be any nonreactive stable fluid having a viscosity at C. of from about to 600,000 cs i.e.; any oil that is used in presently known greases. The term "nonreactive" implies that the oil must be substantially nonreactive, chemically, with the grease thickener, air, water and other materials commonly found in the environment where the grease is utilized. The term "stable" is taken to mean that the fluid does not easily decompose. Thus, the fluid is stable throughout the temperature range in which the grease is to be employed.

Any fluid of the above description is suitable for use 0 al. The high-temperature aromatic polyester is produced in formulating the grease compositions of the invention.

Both natural hydrocarbons and synthetic lubricating oils rived from paraffin base, naphthene base and mixed base distillate or oils; and other petroleum lubricants such as t]jOse derived from coal products. The synthetic oils indude alkyiene polymers, such as polypropylene, butylene, etc and mixture the,f f> &1W. oxide-type polymers, such as are produced by polymerizing propylene oxide in tne presence of ethyl alcohol; esters of alkyiene oxide mers; and polyethers prepared from alkyiene glycols.

These polymeric products, prepared from the various lene ox?es alk?lf e f8 ma polyoxyalkene dlolsr Polya kylene glycol derivatives; that is, the terminal hydroxyl groups can remain as such, or one or both ig rf . \y yl groups can fee ;5moved during the polymerization reaction by esterification or etherificlass of suitable synthetic oils is the dicaresterifying dicarh,=c ,,;,, c,It.h 1 ndiV aHd aWlaic -Jid suberic boxylic acids such as adipic_ acid, azelaic acid, suberic i. acid, sebic acid, alkenyl succimc acid, fumanc acid, maleic ;Icohol 2-ethylhexyl alcohol and dodecyl alcohol (d rb xyll,c.) f ld,ef r mj elude dibutyl adipatedihexyl adipate, di-2-ethylhexyl sebacate and di-n-hexylfumanc polymers. Other classes .of suitable synthetic oil vehicles include alkylated arododecylbenzene, tetradecylbenzene and didode cylbenzene; polyyhydric a icohoi esters, such as i . . it. % i 3 . u i t, Phate esters, such as tncresyl Phosphate and methyldiissr -

Exemplary organopolysiloxanes include dimethylpoand dimethylsiloxytrifraoropropylmethylsiloxy copolymerg_ Th aiorganopolysiloxane polymers can be endblocfced with triof an silyl groupSjPSUch as trimethylsilyl ,, ,,,- t, , B-, , 3. F

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a \. n r c IAA nr>

siloxane fluids having a viscosity of from to 100,000 dered which is utilized as the thickener benzoyl), which is commercially available from the Carn be characterized as a linear repeating chain of units lormma and is a highly crystalline solid having inherent lubricating properties. A detailed description of the p-oxybenzoyl polymer s properties is given in SAMPE Journal, August/

September 1970 in an article authored by J. Economy, et by the condensation of para-hydroxybenzoic acid as de-

The solid polymeric material is used in its finely divided particulate form and mixed with the lubricating oil vehicle to form the grease compositions. Any suitable mixing apparatus, such as a 3-roll mill, industrial shear mixer or the like, can be used in formulating the grease. The particle size of the thickener is not critical, but the average particle size is in the range of 1 to microns. Any major amounts of particles larger than microns result in a "grainy" grease which cannot be tolerated in certain applications.

It should be noted that, for any given fluid vehicle there is a definite range of proportions of fluid to solid powdered p-oxybenzoyl polymer which will result m an acceptable grease. The chemical substituents and viscosity of the fluid are factors determining this range. Excess thickener will cause the composition to be crumbly and , , , . , , unsuitable as a grease, while excess fluid will cause the mixture to be muddy and bleed. Generally, 10 to weight percent thickener, based on the weight of grease composition, forms a satisfactory grease. The optimum proportions for a particular composition are easily determined by simple experimentation.

In addition to the lubricating oil vehicle and the polymeric thickener, the grease compositions can contain small amounts of other materials, such as pigments, dyes, antioxidants, corrosion inhibitors, dispersants, extreme pressure additives, anti-wear additives and the like which are conventionally used. For reasons of economy, it may be desirable to add small quantities of other well-known thickeners to the grease compositions of the invention.

The following examples are illustrative and not to be considered as unduly limiting of the invention which is delineated in the claims. In the examples the following tests were employed to determine the properties of tte grease compositionstions prepared in accordance with the invention.

Evaporation ASTM Method D-927 Drop point ASTM Method D-566 ni A A XT <- i A AT j-c j Ayr t. i <r-

BIeed-AN-G-3 A Modified Methods C-75T and C-77T

Heat stabmty (under mechanical shear as shown by penetration; AMMD-17-52T

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lubncation properties of the different greases were determined by the LFW-1 test, the 4Ball method and a bearing life test. In obtaining the LFW-1 results, an Alpha LFW-1 test machine (described in U.S. Pat. 3,028,746)

was operated in the oscillating mode, using a standard steel ring (Rc60) and a Rc30 steel block at a arc and cycles/minute for 5000 cycles. The 4-Ball tests were run on a Roxanna wear tester in which a %-inch steel ball was rotated against three stationary %-inch steel balls at a rate of r.p.m. at a temperature of 167 F.

for one hour under a constant load of ID or 40 kilograms.

The bearing test was run in accordance with Federal Standard 791, Method 33. The bearing was run at 10,000 r.p.m. under 320 Ibs. load at a temperature of F.

Composition No. 5 70.6 weight percent white mineral EXAMPLE 1 go benzoyl polymer.

Sufficient powdered p-oxybenzoyl polymer, having a particle size in the range of 5-45 microns, was mixed with trimethylsilyl-terminated 3,3,3-trifluoropropylmethylpolysiloxane (1000 cs.) to form a first grease composi-

. -n <- . ,, . , ton containing 20.5 weight percent of the solid polymer.

The oil and thickener were mixed on a 3-roll mill until an intimate dispersion was obtained.

A second grease composition containing 17.8 weight percent of the powdered p-oxybenzoyl polymer and 82.2 weight percent trimethylsilyl-terminated phenylmethylpolysiloxane (660 cs.) was formulated in the same manner as described above.

The physical characteristics and lubrication properties of these grease compositions are listed below:

Grease composition . . . NO. i NO. 2 penetration:

off-mini . . 297 294 Workedk()"stroi:esy.IirirririIIIIIIIiriirriIir" 297 294 e(22 nours/400 P . 6.2 8.7 hours/4500 Fill 9.1 8.7 Evaporation (percent):

22 hours/4po F - H ?

22nours/450 i 5.7 1.4 propping point (F.) 3 453 i, LFW-1 wear scar (mm.) :

Atsoibs.ioad 0.97 0.73 At ibs. load . 1.2 0.97 Four Ball wear scar (mm.):

AJ fnk,g- load- . ---- ]<>

AtlOkg.load . 0. 1.9 The radiation resistance of a grease composition based n the phenyknethylpolysiloxane (similar to grease No.

2) was determined by measuring the grease properties ber re and after exposure to a Megarad radiation dosage.

The properties are as follows :

After _ initial exposure Penetration . 294 294 Bleed (percent) 22/450 F . 8.7 7.7 LrTiscar ""."::""::"" O.I o.l j . j t. i. I.T. j6Se data, demonstrate the heat stability, radiation reslstance and lubricating properties of grease composi-

j -,n. Several grease compositions using various lubricating oil vehiclesfand the peered p-oxybenzoyl polymer det scribed in Example [ were formulated by mixing on a 3ro1 milL grease compositions were as follows:

Composition No. 1 73.6 weight percent dimethylpolysilox (350 CS-) and 26A wei gt powdere JoJ.

p-oxybenzoate)

Composition No. 275.4 weight percent copolymeric siloxane (100 cs.) having mole percent dimethyl siloxy and 50 mole percent 3,3,3-trifluoropropylmethylsiloxy units and 24.6 weight percent powdered p-oxybenzoyl polymer.

Composition No. 3 75.0 weight percent copolymeric siloxane (130 cs.) having mole percent dimethylsiloxy and 50 mole percent phenylmethylsiloxy units and weight percent powdered p-oxybenzoyl polymer.

Composition No. 479.0 weight percent octylmethylpolysiloxane (375 cs.) and 21.0 weight percent powdered P-oxybenzoyl polymer. . .

147 cs.) and 29.4 weight percent powdered p-oxy-

Composition No. 673.4 weight percent polyalkylenef1c?U,UPricat!?g. U (i c) available as "UCON

625 from Umon Carblde Company-and 26.6 weight pe ent Powered p-oxybenzoyl polymer.

, <55 Composition No. 7 64.8 weight percent tnbasic acid ester bricatmg oil (5Q cs.)Lavailable as "Emery 3821.D from Emery Company-and 35.2 weight percent powdered p-oxybenzoyl polymer.

Composition No. 875.7 weight percent tricresyl phosphate (55 cs.) available as "Kronitex AA" from FMC

and 24.3 weight percent powdered p-oxybenzoyl polymer.

Composition No. 9 87.0 weight percent perfluoroalkylpolyether available as "Krytox 153-AC" from du Pont Chemicals and 13 weight percent powdered p-oxybenzoyl polymer.

Composition No. 1087.5 weight percent polyphenylether lubricating oil and 12.5 weight percent powdered p-oxybenzoyl polymer.

The physical properties and lubrication data for each of the compositions is set forth in the following table:

These data demonstrate the effectiveness of various lubricating oils when used as the vehicle in grease compositions of the invention.

Reasonable modification and variation are within the scope of the present invention which is directed to novel grease compositions.

That which is