US3538002A - Modified functional fluids - Google Patents

Description

US. Cl. 252--75 Claims ABSTRACT OF THE DISCLOSURE Compositions of functional fluids having improved oxidation stability. The compositions comprise functional fluids such as synthetic esters, polyphenyl ethers, polyphenyl thioethers, polyphenyl ether thioethers and mixtures thereof in combination with a stabilizing amount of a chelate of a heavy metal of Groups I-IV and VII- VIII with a carbonyl compound of the following formula:

where -R is a fluorinated alkyl radical of from 1-6 C atoms, R is R, alkyl or alkoxy radicals of from l6 C atoms, or cyclic radicals containing conjugated ring unsaturation of up to 10 C atoms and including up to one hetero ring element where the hetero atoms are 0, S 01' N.

This application is a continuation of Ser. No. 517,484, now abandoned.

This invention relates to functional fluids useful over a wide range of temperatures. More particularly the invention relates to functional fluids stabilized against oxidation at elevated temperatures and having noncorrosive properties.

Functional fluids may be single chemical compounds or mixtures containing a plurality of different comopunds. They are used as force transmission fluids for the transmission of pressure, power or torque, as damping fluids, lubricants, cooling media, etc.

Recent advances in mechanical designs especially in the direction of high speed of the moving parts require functional fluids capable of operating at temperatures up to 1000 F. over extended periods of time. New fluids have been developed to meet the higher temperature requirements without thermal degradation.

Although the recently developed high temperature fluids possess extremely good thermal stability, they are increasingly susceptible to oxidation as the temperature rises. The change in viscosity which is a consequence of the oxidation not only alters the operation of, but also may clog up the moving parts of the mechanism which the fluid operates. Hence, when high temperature fluids are to be used under conditions requiring exposure to air or oxygen, it is necessary to inhibit oxidation phenomena. It is an object of this invention to provide novel functional fluid compositions having improved properties which are useful in the temperature range of 400 to 500 F. and up to at least 1000 F.

It is a particular object of this invention to provide novel high temperature lubricant compositions having improved oxidation stability and useful in the temperature range of 400 or 500 F. and up to at least 1000" F.

These and other objects will become evident upon consideration of the following specifications and claims.

It has now been found that the oxidation stability of functional fluids is improved by addition thereto of a States Patent 3,538,002 Patented Nov. 3, 1970 in which R is a fluorinated alkyl radical of from 1 to 6 carbon atoms, R is selected from the class consisting consisting of R, alkyl radicals of 1 to 6 carbom atoms, alkoxy radicals of from 1 to 6 carbon atoms and cyclic radicals containing conjugated ring unsaturation of up to 10 carbon atoms and including up to one hetero ring element. Alkyl, alk in alkoxy and the cyclic radicals are, except for the stated F, oxy and hetero elements, hydrocarbon free of aliphatic unsaturation. R preferably contains at least one carbon atom with F substituents, and is free of H substituents, e.g. CF

In particular, the present invention provides novel, valuable functional fluids wherein the stated metal fluorinated carbonyl chelates are combined with an oxygenated carbonaceous base fluid selected from ester base fluids, polyphenyl ether base fluids, polyphenyl thio ether base fluids and blends thereof.

The chelate additives of the invention can also be advantageously employed in the combination with an amine, to provide functional fluid compositions having still greater ovidative stability.

The metal constituent of the presently useful chelates can be, for example, copper, silver or gold of Group I of the Periodic Table, zinc, cadmium and mercury of Group II, aluminum, gallim, indium and thallium of Group III, titanium, geranium, zirconium, tin, and lead of Group IV, manganese and rhenium of Group VII, and cobalt, nickel, ruthenium, palladium, iridium and platinum of Group VIII. The divalent state of polyvalent metals is preferred, and cobalt is particularly preferred, especially as Co(II).

One class of carbonyl compounds which serve as ligands for the preparation of the presently useful chelates comprises the fluorinated acyclic diketones, i.e., compounds of the formula:

in which R and R are alkyl radicals of from 1 to 6 carbon atoms in which at least one of R and R is fluorine-substituted, and preferably contains at least one perfluorinated carbon atom. Such carbonyl compounds are known to be active ligands for preparation of chelates with the aforesaid metals, the structure of the chelates thereby obtained probably being as follows in the case of a bivalent metal:

With trivalent metals, the chelate structure contains three moles of the carbonyl compound per atom of metal, whereby the chelate contains a hexacoordinate structure instead of the tetracoordinate structure depicted above for chelates of the bivalent metals.

Owing to their easy availability, a very useful class of chelates is that obtained from 1,1,1-trifluoroand l,1,1,5, 5,S-hexafluoroacetylacetone. For convenience, these will be hereinafter referred to as metal fluorinated acetylacetonates. They are readily available in known manner by reaction of the corresponding fluorinated acetylacetone with a salt of the appropriate metal, e.g., the acetate,

chloride or sulfate. Examples of presently useful metal 1,1,1-triand 1,1,l,5,5,5 hexafiuoroacetylacetonates include the copper, barium, manganese, cobalt and nickel triand hexafluoroacetylacetonates.

Metal chelates of other fluorinated acyclic diketones which can be used as antioxidants include: manganous, cobalt or cadmium chelate of 1,1,l-trilluoro-2,4-hexanedione,

nickel chelate of 5,5,6,6,6-pentafluoro-2,4-hexanedione,

aluminum chelate of 1,1,l,2,2-pentafluoro-3,5-

heptanedione,

copper chelate of l,l,2,2,6,6,7,7-octafluoro-3,5-

heptanedione,

zirconium chelate of l,l,l,2,2,6,6,7,7,7-decafluoro-3,5-

octanedione,

titanium chelate of 1,l,l-trifluoro-2,4-decanedione,

cobalt chelate of 1,1,1-trifluoro-2,4-decanedione,

tin chelate of 1,1,l,2,2,3,3,4,4,5,5,6,6-tridecafluoro-7,9-

pentadecanedione,

manganous chelate of 5,5,6,6,6-pentafluoro-2,4-

hexanedione,

iridium chelate of 1,1,1,2,2-pentafluoro-3-propyl-4,6-

nonanedione,

germainum chelate of 1,1,l,2,2-pentafluoro-3,5-

heptanedione, and the like.

Another class of carbonyl compounds Which serve as ligands for preparation of the presently useful metal chelates can be those in Which R includes a ring containing conjugated unsaturation, either heterocyclic including O, S, or N as the hetero atom, or carbocyclic including aryl, alkaryl or aralkyl. For example, these radicals may be furyl, thienyl, pyranyl, pyridyl, phenyl, uor fl-naphthyl, tolyl, 3-butylphenyl, benzyl, etc. Examples of such chelates are chelates of aryl, alkaryl and aralkyl diketones such as:

cobalt chelate of 4,4,4,-trifiuoro-1-phenyl-1,3-butanedione, nickel chelate of 4,4,4,-trifluoro-l-phenyl-1,3-butanedione, cobalt chelate of 5,5,5-trifluoro-l-phenyl-2,4-pentanedione, manganese chelate of 5,5,5-trifluoro-1-tolyl-2,4-pentanedione, nickel chelate of 4,4,5,5,5-pentafluoro-1-phenyl-l,3-

butanedione, copper chelate of 5,5,5-trifluoro-l-phenyl-2,4-pentanedione, cobalt chelate of 4,4,4-trifluoro-l-xylyl-l,3-butanedione, copper chelate of 4,4,4-trifluoro-I-a-naphthyI-LS-butanedione, barium chelate of 4,4,5,5,6,6,7,7-octafluoro-l-(m-propylphenyl)-1,3-heptanedione, cobalt chelate of 9,9,9-trifiuoro-l-phenyl-1,3-nonanedione, manganese chelate of 1,1,l-trifluoro-6-phenyl-2,4-hexanedione, cobalt chelate of 5,5,6,6-tetrafluoro-1-(p-isopropylpheny1)- 2,4-hexanedione and the like, as Well as heterocyclic chelates such as copper chelate of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, nickel chelate of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, cobalt chelate of 4,4,4-trifluoro-I-(Z-thienyl)-l,3-butanedione, copper chelate of 4,4,4-trifluoro-l-(2-furyl)-l,3-butane- I dione, nickel chelate of 4,4,4-trifluoro-l-(2-furyl)-1,3-butanedione, copper chelate of 4,4,4-trifiuoro-l-(3-furyl)-l,3-butanedione, nickel chelate of 4,4,4-trifiuoro-l,2-pyridyl-1,3-butanedione, zinc chelate of 4,4,5,5,5-pentalluor -1-thienyl-1,3-per1- tanedione,

aluminum chelate of 4,4,5,5-tetrafluoro-1-thienyl-1,3-pentanedione,

manganese chelate of 4,4,4-trifluoro-1,3-pyridyl-l,3-

butanedione,

cobalt chelate of 4,4,4-trifluoro-l,3-pyridyl-l,3-butanedione,

cobalt chelate of 5 ,5 ,5 -trifiuoro-l-thienyl-2,4-pentanedione,

nickel chelate of 5,5,5-trifluoro-1-thieny1-2,4-pentanedione,

cobalt chelate of 4,4,5,5,5-pentafluoro-l-benzothienyl-l,3-

pentanedione,

aluminum chelate of 5,5,5-trifluoro-l-pyranyl-2,'4-pcntanedione,

chromium chelate of 7,7,7-trifiuoro-l-thienyl-1,3-heptanedione, and so forth. The carbonylic ligand can also be an acylacetate ester of the formula:

where R is a fluorinated alkyl radical as defined above, and R is an alkyl hydrocarbon radical of from 1 to 6 carbon atoms. Chelates formed from the use of such acylacetate esters as illustrated by:

cobalt chelate of ethyl trifiuoroacetoacetate,

copper chelate of methyl trifiuoroacetoacetate,

mercury chelate of t-butyl trifluoroacetoacetate,

nickel chelate of ethyl 4,4,5 ,5,5-pentafluoro-3-oxovaleric acid,

rhenium chelate of hexyl 4,4,5 ,5 ,S-pentafluoro-B-oxovaleric acid,

aluminum chelate of ethyl 4,4,5,5,6,6,7,7,8,8-decafluoro- 3-oxooctanoate,

cobalt chelate of ispropyl 5,5,5-trifluoro-4,4-bis(trifluoromethyl) -3-oxovalerate,

aluminum chelate of ethyl trifluoroacetoacetate,

manganese chelate of ethyl trifluoroacetoacetate,

copper chelate of methyl 4,4,5 ,5 ,5-pentafluoro-3-oxovalerate,

lead chelate of ethyl 8,8,8-trifluoro-3-oxooctanoate,

cobalt chelate of ethyl 9,9,9-trifiuoro-3-oxononanoate, and

so forth.

The antioxidant additive employed in the formulated fluids of this invention can consist of the metal fluorinated carbonyl compound alone or in combination with further oxidation-suppressing additives. It has been found that particularly effective. suppresession of the oxidative degradation of the present base stock blends is produced by combination of amines with the metal carbonyl compounds.

For the present purpose, useful amines contain at least 12 carbon atoms. They may be either aromatic or aliphatic and are usually secondary or tertiary amines. Presently useful aromatic amines include arylamines and arylidene amines wherein the benzene nuclei are attached to the amine nitrogen atoms either directly by a ring carbon atom or through a single aliphatic carbon atom. The amines contemplated herein are free of aliphatic (olcfinic and acetylenic) unsaturation, contain from 12 to 36 carbon atoms, and consist of hydrocarbon radicals and amino nitrogen atoms, which may or may not have oxy (oxygen joined to atoms selected from.C and H) or thio (joined to 2 C atoms) radicals as substituents. Generally, the presently contemplated amines will include from 1 to 4 nitrogen, from O to 3 oxygen, and from'O to 2 sulfur atoms.

Illustrative of presently useful aromatic amines are aryl amines such as naphthylamine (a or p), naphthyenediamine, 4-aminobiphenyl, Z-aminobiphenyl, 4-aminobiphenyl, diphenylamine, 4-aminodiphenylamine, N-phenylphenylenediamine, N-ethyl-ot-naphthylamine, 2,4-diaminox diphenylamine, 1,2-diphenylethylenediamine, N-benzylaniline, methylenedianiline, l-aminoanthracene, l-aminophenanthrene, di-o-tolylamine, 4-dimethylaminodiphenylamine, N,N-diphenylethylenediamine, o-ditoluidine (3,3- diamino-4,4-dimethylbiphenyl), N phenyl a naphthylamine, N-phenyl-,B-naphthylamine, N-cyclohexyl-a-naphthylamine (or ,8), N-p-tolyl-,B-naphthylamine, triphenylamine, N,Ndiphenyl-p-phenylenediamine, di-a-naphthylamine, di-fi-naphthylamine, triphenylamine, dibiphenylylamine, N,N'-diphenylbenzidine, p-aminophenyltriphenylmethane, N,Ndinaphthylmethylenediamine, N,N'dinaphthyl-p-phenylenediamine, N-[ l-aminocyclohexy) methyl] N-phenyl-p-phenylenediamine, acridine, phenothiazine, and so forth.

Exemplary of phesently useful arylidene amines are N,N-dibenzylidene-p-phenenediamine,

N,N'-bis (2,3-dimethylbenzylidene -p-phenylenediamine,

N,N-bis Z-hydroxybenzylidene -p-phenylenediamine,

N,N'-bis Z-ethoxybenzylidene -p-phenylenediamine,

N ,N'-bis 2-hydroxybenzylidene ethylenediamine,

N,N-bis- Z-hydroxybenzylidene 1,2propylenediamine,

N,N-bis(Z-hydroxybenzylidene)-1,3-propylenediamine,

N,N'-bis (3-ethoxy-4-hydroxybenzylidene) -1,2-propylenediamine,

N,N-bis 2-hydroxy-4-methylbenzylidene -p-phenylenediamine,

N-3-methylbenzylidene-3-octylaniline,

N-2-hydroxybenzylidene-4-hexadecylaniline,

N,N'-bis (3 ,4-methylenedioxybenzylidene) -p-phenylenediamine,

N,N'-bis( (2,3-dimethoxybenzylidene)-p-phenylenediamine,

N,N-bis 2methoxybenzylidene -p-phenylenediamine,

N,N-bis Z-hydroxybenzylidene -o-phenylenediamine,

N,N'bis 3,4-methylenedioxybenzylidene -p-phenylenediamine,

N,N-bis 3 -ethoxy-4-hydroxybenzylidene) -p-pl1enylenediamine,

N- (3 -ethoxy-4-hydroxybenzylidene) -4-dodecylaniline,

N,N'-bis (4-phenoxybenzylidene -p-phenylenediamine,

N,N'-dibenzylidene-1,Z-diphenylethylenediamine, and the like,

Exemplary of presently useful aliphatic amines are, for example, N,N-dimethyloctadecylamine, N,N-diethyloctadecylamine, N,N-dihexyloctadecylamine, N,N-dimethylhexadecylamine, N,N dimethyleicosylamine, N ,N dibutylhexadecylamine, N,N-dimethyldodecylamine, trihexadecylamine, N,N-dimethyldecylamine, trinonylamine, N- ethyl-N-methylhexadecylamine, N-butyl-N-propyloctadecylamine, and so forth.

To provide the fluid compositions of this invention, the metal fluorinated chelates of the nature stated above are combined, with or without addition of an amine, with a base fluid. These fluid compositions can be used for operation and lubrication of the moving parts of mechanisms operating in temperature ranges of 400 F. to 700 F. and up to 1000 F. v

A particularly advantageous base fluid for use in mechanisms operating at 400 F. to 700 F. comprises the polyphenyl ethers. The polyphenyl ethers employed in the composition of this invention have from 3 to 7 benzene rings and from 1 to 6 oxygen atoms joining the benzene rings in chains as ether linkages. One or more of these benzene rings may carry hydrocarbyl substituents, which, for thermal stability, must be free of CH and aliphatic CH. Thus, preferred aliphatic substituents are lower saturated hydrocarbon radicals (1 to 6 carbon atoms) like methyl and tertiarybutyl, and preferred aromatic substituents are aryl radicals like phenyl, tolyl, t-butylphenyl and ot-cumyl. Benzene rings supplied in the hydrocarbyl substituent contribute to the total number of benzene rings in the molecule.

Exemplary of the polyphenyl ethers containing aliphatic carbon which are suitable for base fluids are 3- ring polyphenyl ethers like 1-(p-methylphenoxy)-4-phenoxybenzene and 2,4-diphenoxy-l-methylbenzene, 4-ring polyphenyl ethers like bis[p-(p-methylphenoxy)-phenyl] ether and bis[(p-tert-butylphenoxy)-phenyl]ether, and so forth. Polyphenyl ethers consisting exclusively of henzene rings and including ether oxygen atoms linking said rings are exemplified by the triphenoxy benzenes and aryl substituted polyphenyl ethers such as biphenylyl phenoxyphenyl ether, biphenylyloxyphenyl phenoxyphenyl ether, biphenyl ether, dibiphenylyloxybenzene, bis(biphenylyloxyphenyl)ether, and the like.

A preferred class of the polyphenyl ethers are those consisting of benzene rings joined in a chain by oxygen atoms as ether linkages between each ring, of the formula C H O-(C H O-) -C H where n is an integer of from 1 to 5. Example of these polyphenyl ethers are the his (phenoxyphenyl) ethers (4 benzene rings joined in a chain by 3 oxygen atoms), illustrative of which is bis(mphenoxyphenyl)ether. The bis(phenoxyphenoxy) benzenes, which are particularly valuable, are illustrated by m bis(m phenoxyphenoxy)benzene, m-bis(p-phenoxyphenoxy)benzene, o-bis(o-phenoxyphenoxy)benzene, and so forth. Further, the polyphenyl ethers contemplated herein include the bis(phenoxyphenoxyphenyl) ethers such as bis[bis[m (m phenoxyphenoxy)phenyl]ether, bis[p (p phenoxyphenoxy)phenyl]ether, and m- (mphenoxyphenoxy)phenyl m (o phenoxyphenoxy) phenyl ether and the bis(phenoxyphenoxyphenoxy) benzenes such as m-bis[m-(m-phenoxyphenoxy)phenoxy] benzene, p bis[p-(m-phenoxyphenoxy)phenoxy]benzene and m-bis[m-(p-phenoxyphenoxy)phenoxy]benzene.

The preferred polyphenyl ethers are those having all their ether linkages in the meta-positions, because of their wide liquid range and high thermal stability. Mixtures of the polyphenyl ethers, either of isomers or of homologs, can also advantageously be used in some applications, especially where particular properties such as lower solidifications points are required. Mixtures of polyphenyl ethers in which the nonterminal phenylene rings are linked through oxygen atoms in the meta and para positions have been found to be particularly suitable to provide compositions with wide liquid ranges. An example of such preferred polyphenyl ether compositions are those containing, in percent by weight, from about 0 to 6% of o-bis(m-phenoxyphenoxy)benzene (1), about 40 to of m-bis(m-phenoxyphenoxy)benzene (2), about 0 to 40% of m-[ (m-phenoxyphenoxy) (p-phenoxyphenoxy)] benzene (3), about 0 to 12% of p-bis(m-phenoxyphenoxy)benzene (4), about 0 to 10% of p-[(p-phenoxyphenoxy) (m-phenoxyphenoxy)Jbenzene (5), and about 0 to 6% of m-bis(p-phenoxyphenoxy)benzene (6). Typical compositions of such preferred compositions are listed below. The number in parentheses refers to the compound mentioned above having the same number thereafter.

The above-discussed polyphenyl ether base fluids are especially thermally stable members of the class of base fluids which are aromatic rings connected by oxygen atoms.

A closely related class of base fluids are the all meta 7 linked polyphenyl thioethers represented by the following structure:

wherein n is a whole number from 1 to 3, polyphenyl thioethers represented by the following structure:

(DUO

and phenyl mercapto biphenyls represented by the strucdiner y wherein x and y are Whole numbers from 1 to 3 and the sum of x and y is from 2 to 6.

Typical examples of the polyphenyl thioether are mbis(phenylmercapto)benzene, m bis(m-phenylmercaptophenyl[mercapto])benzene, phenylmercaptobiphenyl, obis(o phenylmercaptophenyl)sulfide, m bis(p-phenylmercaptophenyl)sulfide, 1,2,3; 1,2,4, or 1,3,5 tris(phenylmercapto)benzenes; 2,2 or 4,4 bis(phenylmercapto) biphenyl, o, In, or p-bis (o, m, or p-phenyl mercaptophenylmercapto)benzene, or -bis (phenylmercapto)-ar (phenylmercapto)benzene, 2,2, 4,4'-tetra and 2,2, 3,3, 4,4'-hexa (phenylmercapto) biphenyls.

Also useful as functional fluids in this invention are mixed polyphenyl ethers-thioethers corresponding to the formula:

wherein R is a phenyl group, R is a phenylene group and Y and Y are selected from the group consisting of O and S provided that at least one of Y and Y is S and one of Y and Y is O and n is a whole number of from 14. Examples of such mixed ether-thioethers are: 2 phenyltmercapto 4' phenoxydiphenyl sulfide, 3 phenoxyl 4'- phenylmercapto diphenyl sulfide, 2,2 bis(phenylmercapto)diphenyl ether, etc. The phenyl and phenylene groups of such compounds may contain substituents such as an alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms; halogen and perfluoroalkyl of 1 to 4 carbon atoms. Examples are 3,3 bis(xylylmercapto)diphenyl ether, 3,3 bis(3-chlorophenylmercapto)diphenyl ether, 4,4 bis(m trifluoromethyl phenylmercapto)diphenyl ether, 3,4 bis(m isopropoxyphenylmercapto)diphenyl ether, 2-p-tolyloxy-3-phenylmercapto diphenyl sulfide, etc.

The high temperature base fluids empolyed in the compositions of this invention can also comprise synthetic ester base fluids. These are fluids of lubricating viscosity and thermally stable to at least about 400 R, which are esters of alcohols containing at least 4 carbon atoms and which generally contain more than one ester group, and contain a total of at least carbon atoms. They may be esters of polyhydric alcohols, of polybasic acids, or both.

The stated synthetic esters are generally aliphatic in nature, as distinguished from the essentially aromatic nature of the polyphenyl ethers, and their properties and response to additives have correspondingly been found to be usually of a different kind. Unexpectedly, however, the presently contemplated metallic additives have also been found to provide significant improvement in the oxidation resistance of the stated ester type of base fluid. Ester fluids are illustrated by diesters of long chain (C and above) dicarboxylic acids like azelaic acid with longchain branched primary alcohols of the C to C range; the esters of long chain (C and above) monobasic acids such as pelargonic acid with glycols such as polyethylene glycols; complex esters formed by linking dibasic acid half esters through a glycol such as dipropylene glycol, a polyethylene glycol of 200 molecular weight, and so forth. These methods of forming polyester type lubricant fluids can be combined and permuted, and different polyester products can be blended. Simple esters providing suitable fluids can be exemplified, for example, by bis(Z-methylbutyl) sebacate, bis(l-methyl-4-ethyloctyl) sebacate, bis (2-ethylhexyl) sebacate, dipropylene glycol dipelargonate, the diesters of acids such as sebacic, azelaic and adipic acid with complex Cg-Cl primary branched chain alcohols such as those produced by the 0x0 process, polyethylene glycol 200 bis-(2-ethylhexyl sebacate), diisoarnyl adipate, 1,6-hexamethylene glycol di(2-ethylhexanoate), bis(dimethylamyl) azelate and so forth.

Ester fluids with particularly good high temperature oxidation resistance are provided by neopenthyl polyol esters. The alcohols from which these esters are derived have the carbon structure of neopentane, with a central carbon atom surrounded by 4 substituent carbon atoms. Included in the neophenyl polyols are neopentyl glycol, trimethylolethane, trimethylolpropane and pentaerythritol. Generally, the base fluids comprising neopenthyl polyol esters are the esters with monocarboxylic acids. Such esters are generally more oxidatively and thermally stable than the dibasic acid esters. The useful esters of the neopentyl polyols include, for example, the esters of trimethylol propane, neopentyl glycol and pentaerithrytol with normal, branched chain and mixed acids having chain lengths varying from C to C Thus, an illustrative series of esters are trimethylolpropane tri-n-pelargonate, trimethylolpropane tricaprate, trimethylolpropane tricaprylate, the trimethylolpropane triester of mixed octanoates, and the like.

For further description of still other ester fluids adapted for use as lubricant base stocks and useful in the provisions of blends of this invention, reference may be made, for example, to the discussion in Gunderson et 211., Synthetic Lubricants (Reinhold, 1962).

The base fluid in the present compositions may comprise polyphenyl ether, a polyphenyl thioether, a polyphenyl ether-thio-ether or a combination of two or more of the foregoing. Compositions comprising combinations of esters and the polyphenyl ethers have desirable fluidity at low temperatures. While various esters have been found to blend with the polyphenyl ethers to provide blends having thermal and oxidative stabbility approaching the stability of the polyphenyl ethers, especially valuable base fluids have been found to be provided by combinations of a polyphenyl ether with a neopentyl alcohol ester. These compositions posses both fluidity at low temperature and stability at elevated temperatures. The preferred polyphenyl ethers for use in this connection are the bis(phenoxyphenox-y)benzenes, of the composition C6H5O(C6H4O)3C6H5 Where each C6H5 is a phenyl and each C H is a phenylene radical. Those with the ether linkages between benzene rings in meta positions, partly or wholly, are especially preferred. The stated neopenthyl esters are esters of neopentyl alcohols such as pentaerythritol, trimethylolethane, trimethylolpropane and neopenthyl alcohol with straight chain, branched chain and mixed C -C acids such as n-heptanoic and neoheptanoic acid. Compositions of the stated valuable nature are provided by combining 25-75 weight percent of the ester base fluids with 75-25 weight percent of the polyphenyl ethers.

As noted hereinabove, antioxidant additives activity is usually not found to be general to difierent classes of lubricant base fluids. However, compositions comprising the presently employed chelates have unexpectedly been found to posses improved properties compared to the base stock alone with base oils of diverse kinds.

Thus, in its broadest aspects, this invention relates to functional fluid compositions in which the base stocks are those described above, or can be a lubricating oil, preferably an oil which is thermally stable up to about 500 F. Examples of such oils include, hydrocarbon oils, siliconcontaining oils, fluorinated oils, and so forth.

Illustrative of hydrocarbon oil base fluids are the aromatic hydrocarbons, particularly condensed ring structures such as biphenyl, alkylbiphenyls such as monoand diisopropylbiphenyl, and terphenyls, quaterphenyls, their alkyl derivatives such as dimethylterphenyl, and the like. Hydrogenated derivatives of these aromatic hydrocarbons, including alicyclic rings and alkylated alicyclic rings, can also be used. Mineral oils, paraflinic and naphthenic, can be provided with improved high temperature stability by super-refining. Super-refining is the removal or substantial reduction of the polar impurities, unsaturated and unstable hydrocarbon structures by exhaustive hydrogenation, severe acid treatment, adsorption, or a combination of these processes. Oxidation rates at 500 F. are approximately the same for the superrefined mineral oils as for the ester lubricants. Uuseful mineral oils are the petroleum products boiling above the kerosene range; a typical mineral oil base for extreme pressure lubrication will be characterized by a viscosity of 35-350 Saybolt Universal Seconds at 212 F., a viscosity index of -25 to +150 and a flash point of 275 to 600 F.

Silicon-based lubricant fluids are exemplified by silanes. such as n-dodecyl tri-n-decyl silane and diphenyl di-ndodecyl silane; the silicone polymer fluids such as dimethyl silicone and methyl phenyl silcone polymers, and disiloxanes; and tetraalkyl orthosilicate esters such as ditert-butyl di-Z-ethylhexyl orthosilicate, 1,3-di-tert-butoxy- 1,1,2,2-tetra(2-pentoxy) disiloxane, tetra-(methylphenyl) silicate, tetraphenyl silicate, tetra(2-2-ethylhexyl) silicate, and so forth.

Illustrative of fluorine-containing base fluids are fluorinated esters like bis(perfluoroamyl) phthalate, bis(perfluorohexyl) 3-methylglutarate, and 1,1-H-nonafluoropentyl nonafluoropentanoate; and the polymers of chlorotrifluoroethylene, for example, with average molec ular weights of about 5004000, and so forth.

The compositions of this invention comprise a major proportion of the base fluid and a minor proportion of the metal chelate (and, when present, amine) additives. In general, the concentrations to be employed for effective improvement of the base fluid oxidative degradation resistance by the metal chelate and, when present, amine antioxidant compounds are between about 0.01% and individually or jointly, by Weight of the fluid. Particular effective amounts depend on the nature of the individual additive and of the base fluid. To supply additive concentrates, adapted for later formulation of finished lubricant compositions, useful compositions may comprise up to about 1:1 Weight ratio of the additives of this invention and the base fluid. In any case, at least an adjuvant amount sufficient to produce an improvement in the oxidation stability of the base fluid will be employed. Whether or not the desired antioxidant eflect is obtained is readily determined by use of conventional testing procedures.

The compositions of this invention, in addition to the base fluid and the metal chelate compound, can additionally include further additives. For example, these can include sludge inhibitors and detergents such as the oilsoluble petroleum sulfonates, to loosen and suspend products of decompositions and counteract their effect, viscosity index improvers, as exemplified by alkyl methacrylate polymers, pour point depressants, oiliness agents, antiwear and lubricity agents, corrosionand rust-inhibitors, anti-foam agents, and so forth.

The invention is illustrated but not limited by the following examples, in which the tests employed to determine the reported antioxidant eifects of the additive compounds when employed With the base fluid are conducted as follows:

For determination of the antioxidant effect of the present additive compounds, air is bubbled through heated samples. The present change in F.) viscosity from before to after oxidation is an index of antioxidant activity: desirably, the change is low. For a preliminary oxidation test, conditions employed are 450 F. temperature and a flow rate of 1 liter of air per hour, continued for 16 hours. Samples are run in the presence of metal wires (Fe, Ag, Cu, Al) as a check on the effect of such metals on oxidation temperature of 450 F. and in air flow rate of 5 liters per hour, continued for 24 hours.

EXAMPLE 1 Additive: Average percent increase None 48 Co(HFAA) 22 Co(TFAA) 2O Co(T'IFA) 17 Co(ETFA) 43 Cu(HFAA) 33 Cu(TFAA) 26 Cu(ETFA) 37 Mn(HFAA) 30 Mn(TFAA) 39' Mn('1'TFA) 37 Mn(ETFA) 36 HFAA=hexafluoroacetylacetonate TFAA:trifluoroacetylacetonate 'ITFA:thenoyltrifluoroacetonate (4,4,4 trifluoro 1 -2- thienyl-l,3-butanedione ETFA=ethyltrifluoroacetolacetate Using the 24 hour, 5 liter per hour test described above, results obtained with the same ester base fluid were as follows:

Additive Average percent 1 increase None 710 Co(TTFA) 250 Co(HFAA) 180 In each of these tests little or no corrosion of the metal wires was observed.

EXAMPLE 2 This example illustrates use of the metal fluorinated carbonyl chelate additives of this invention in combination with secondary amines.

In the 16 hours, 1 liter/hour test described above, results were as follows for TMP ester:

Average Amine percent additive 1 increase Metal additive:

one. .1 None 48 D 0 PA 28 Do PANA 1 27 Ni(HFAA)2 DOPA 1f) Ni(HFAA)2 PANA 20 Ni(TFAA)z DOPA 23 Nit'lFAAh. PANA 8 Ni('ITFA)2 DOPA 26 Ni(ETFA)2 PANA 14 Mn(TFAA)2 PANA 17 1 Filtered.

NorE.HFAA, "IFAA, 'ITFA, EIFA: see Example 1; DOPA=di- (oetylphenyl) amine; PANA=phenyl-a-naphthyahnine.

In the 24 hour, liter/hour test, in the same ester base fluid, results obtained were:

Average Amine percent additive increase Metal additive:

None None 710 Ni(HFAA)z DOPA 270 As in the previous example no corrosion of the metal wires was observed.

EXAMPLE 3 This example illustrates improvement of the oxidation resistance of a base fluid by a metal fluorinated carbonyl chelate in combination with a tertiary amine.

With the test method described above, run for 16 hours at 1 liter/hour, the following results were obtained in TM? base stock.

Average percent increase Amine additive Metal Additive 1 H FAA=hexailuoroaeetylacetone. qs N=tripl1enylamine;DMODA=dimethyloctadeeyl amine (Me2NClsH9s) At 24 hours, 5 liters/hour, in the same base stock results were as follows:

Average percent Amine additive increase Metal additive:

e None 710 C0(HFAA)2. .do 200(220, 180) 00(HFAA)2. N 70 Co(HFAA) Di\1ODA 135 Co(HFAA)2. Acridine 65 C0(HFAA)2 DMODA and aeridine EXAMPLE 4 (3) Ethyl trifluoroacetoacetates.-With the exception of AI(ETFA) the same general procedure for preparing the hexafluoroacetyland trifluoroacetylacetonates is followed. AI(ETFA) is prepared in an aqueous sodium acetate buffered solution of aluminum nitrate.

(4) Thenoyltrifiuoroacetonates. The same general procedure used for preparing the metal chelates of the other ligands is followed except that 50% aqueous methanol is used as a solvent.

COLORS AND MEL'llNG POINTS OF METAL CHELATES AND DERlVATlVES Melting Chelate: Color point, C.

Co(I-IFAA)2 Orange-brown. 192-194 Ni(HFAA)2 208-210 FGU'IFAAM 46-47 Cu(HFAA)Z 117-118 Mn(HFAA) 158-160 Ti(HFAA)4 88-90 C HFAA); 111-114 AMHFAA); 88-89 Z11(HFAA)2 do 151-153 C0(TFAA)2 Pale orange. 184-187 N1(TFAA)2 Pale blue-green 1 255-280 Fe(IFAA)3 Orange 114-116 CIl(TFAA)z Blue green 196-197 Mn(TFAA)2 ellow 138-141 C1'(TFAA) Brown 126-132 00(ETAA)? Orange NKETAAM Green. 205-207 Fe(ETFAAl3 Orange-red Cu(ETFAA)z Pale bluc-greem.

Mn(ETFAA)2 White AKETFAA):

CQUPTFMQ Ni(T1.FA)2

Cu('I"[FA)g MnUlTFAh Fe(lTFA) Cr-(TTFAM AKTTFAM Wl to 205-206 1 Decomposes. 2 Wide range.

EXAMPLE 5 This example describes utilization of some of the present additives in other base stocks.

Compositions are prepared by combining base fluids, metal fluorinated chelates and amines as stated below.

1 The mixture described in Example 1.

The amine additives are present in concentrations of O to 1%, and the metal chelates, in concentrations of 1%, by Weight of the base fluid. The compositions have improved oxidation stability compared to the base fluids and do not corrode metal wires used in the oxidation stability tests.

The compositions of this invention are particularly valuable as high temperature lubricants since they are stable to both thermal and oxidative degradation when used in lubricate moving parts subject to elevated temperatures. Most of the compositions will opperate for extended periods at temperatures of 400500 F. without failure and many will operate for somewhat shorter periods of time at temperatures up to nearly 1000 F.

The compositions, moreover, are valuable as force transmitting media for translating the movement of one or more mechanical means to one or more movable devices. For instance, they may be used in hydraulic brake devices in which the movement of a piston in a master cylinder is transmitted by the fluid to one or more brake actuating devices. They also are useful in hydraulic systems actuated by a pump, e.g., in a fluid motor comprising a constantor variable-discharge piston pump which is caused to rotate by the pressure of the fluid of the system.

For use in a conventional automatic transmission, the presently provided functional fluid compositions are contained in the outer casing of the transmission device, which casing is attached to the usual engine crankshaft and flywheel and rotates therewith. Within the fluid is a coupling comprising an impeller connected to said casing and a turbine which is connected to the drive shaft of the vehicle. The turbine is driven by the motion of the fluid in response to the rotation of the impeller, as the casing to which the impeller is attached is actuated by the crankshaft and flywheel.

In all of these applications the fluid compositions of this invention are particularly useful because of their unusual stability to oxidative degradation, their thermal stability and their lubricating properties which render the system self-lubricating.

While the invention has been described with particular reference to various specific preferred embodiments thereof, it is to be appreciated that modification and variations can be made without departing from the scope of the invention, which is limited only as defined in the appended claims.

I claim:

1. A functional fluid composition consisting essentially of a fluid neopentyl polyol ester or a blend of said ester containing about 25-75 weight percent ester and a fluid polyphenyl ether, a fluid polyphenyl thioether, a fluid polyphenyl ether-thio-ether or ether mixture, and an amount, suflicient to stabilize said ester against oxidation, of a chelate of cobalt with hexafluoroacetylacetone.

2. A functional fluid composition consisting essentially of a fluid neopentyl polyol ester or a blend of said ester containing about 25-75 weight percent ester and a fluid polyphenyl ether, a fluid polyphenyl thioether, a fluid polyphenyl ether-thio-ether or ether mixture, and, an amount, sufficient to stabilize said ester against oxidation, of a chelate of nickel with hexafluoroacetylacetonate.

3. A functional fluid composition consisting essentially of a fluid neopentyl polyol ester or a blend of said ester containing about 2575 weight percent ester and fluid polyphenyl ether, a fluid polyphenyl thioether, a fluid polyphenyl ether-thio-ether or ether mixture, and an amount, sufficient to stabilize said ester against oxidation, of triphenyl amine and cobalt bis hexafluoroacetylacetonate.

4. A functional fluid composition consisting essentially of a fluid neopentyl polyol ester or a blend of said ester containing about 25-75 weight percent ester and a fluid polyphenyl ether, a fluid polyphenyl thioether, a fluid polyphenyl ether-thio-ether or ether mixture, and an amount, suflicient to stabilize said ester against oxidation, of acridine and cobalt bis hexafluoroacetylacetonate.

5. A composition consisting essentially of a mixture of bis(phenoxyphenoxy)benzenes and trimethylolpropane trienanthate and an antioxidant additive consisting essentially of cobalt (II) chelate with hexafluoroacetyl acetone.

6. A composition consisting essentially of a mixture of bis(phen0xyphenoxy)benzenes and trimethylolpropane trienanthate and an antioxidant additive consisting essentially of an amine chosen from the group consisting of aryl amine, arylidene amine and aliphatic amine, said amine containing from 12-36 carbon atoms, from 1-4 nitrogen atoms, from O3 oxygen atoms and from 0-2 sulfur atoms, useful as an antioxidant in an ester-based functional fluid and nickel (II) chelate with hexafluoroacetylacetone in an amount sufficient to stabilize said composition against oxidation.

References Cited UNITED STATES PATENTS 2,795,549 6/1957 Abbott et al. 3,360,467 12/1967 McHugh et a1.

MAYER WEINBLATT, Primary Examiner D. SILVERSTEIN, Assistant Examiner US. Cl. X.R.