CA2217862A1

CA2217862A1 - Partial synthetic transmission fluids with improved low temperature properties

Info

Publication number: CA2217862A1
Application number: CA002217862A
Authority: CA
Inventors: Ricardo Alfredo Bloch; Raymond Frederick Watts; Manoj Tandon
Original assignee: Individual
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 1995-07-17
Filing date: 1996-07-12
Publication date: 1997-02-06
Also published as: WO1997004049A1; AU6545496A; EP0839176A1; JPH11509261A; AU711941B2

Abstract

This invention relates to a composition and method for producing partial synthetic transmission fluids having a -40 ~C Brookfield viscosity no greater than 10,000, preferably no greater than 5,000 centipoise without the need to incorporate viscosity modifying amounts of high molecular weight polymeric viscosity modifiers.

Description

PARTIAL SYNTHETIC TRANSMISSION F~UIDS WITH
IMPROVE{) LOW TEMP~RATURE PROPE~TIES

This invention relates to compositions and methods of improving ~,upe,lies of lr~"s",ission fluids particularly to obtaining partial sy~ll,elic a--lo",dlic l,a,)s",ission fluids of improved low temperature properties.

Automobile manufacturers continue to seek ways to improve aLIl~llldLic ll al ISI I ,ission oper~lio" es,ue- ially at low te~ "~e~ alure through advances in automatic ltd"sm.ssio,~ fluid (ATF3 leclllloloy~r. Improve~"e.,l~ in llal~s",issio-, operation at low te,,,,ueral-Jres are accomplished by lowering the allowable viscosil~ of the ATF at -40~C as measured by a Brookfield visco~l~eter. Historically, the "Id~il"um allowable Brookfield viscosil~ at -40~C
of an ATF was ~0 000 ce"lipoise (cP). This upper limit ~-cisted until ap~ru,.i,,~alely 1990 when it was recl~ced to 20000 cP. This dl~,.,alic recl~ction in viscosity at low temperatures siy~irica~ r improved l~a"s",issio"
operation which has been well documented (SAE paper 8703~6 (1987)).
More recently 40~C viscosill~ limits have been further re~ Ice~ to a maximum of 15 000 cP and in some applicalio"s to no more than 5 000 cP.

Meeting these very ~l,i"y~nl low temperature requirements has been the focus of much research into basestock quality synthetic base oils and flow improvers. We have now found that merely adding synthetic base oils to conve,-lio"al mineral oils viscosilies in the range of 5 000-10 000 cP cannot be achieved without the incorporation of a "flow improver". A ' flow improver sometimes referred to as a pour point depressant is a compound that influences the cryst~ tion of wax in the lubl icali- ~y oil as the temperature is decreased. More specifically, the "flow improver" modifies the crystal structure of the wax such that it cannot form "gel structures" in the lUbl icalll.
This phenomenon is well known and is described in for example "Crystal-Growth Poisoning of N-Paraffin Wax by Polymeric Additives and its Relevance to Polymer Cryst~ tion Mechanisms" G. A. Holder and J. Winkler Nature 207 (4996) 719-21 What has previously not been reported is the dralll~lic adverse effect of the wax on the -40~C viscosity of parlially synthetic ATF's.

W O 97/04049 PCTrUS96/11681 This invention overcomes this low temperature problem by providing partially s~"Ll,elic ATFs with 40~C viscosiLies approaching the theoreLical viscosities of wax-free ATF s i.e. fully synthetic ATF s.

SUMMARY OF THE INVENTION

This invention relates to a L,;~"s",ission fluid comprising:

(a) a natural lubricating oil having a kinematic viscosily from 2.0 to 8.0 mm2/s at t 00~C;

(b) a synthetic lul~ri~li~,g oil having a kinematic viscosily from 2 to 100 mm2/s at 1 00~C;

(c) a seal swelling agent;

(d) 0.001 - 5.0 weight pe-ce"t of a friction modifier; and (e) 0.05 to 2.0 weight percent of a non-wax gelling flow improver;

providing the fluid has a kinematic viscosiLy of at least 3.8 mm21s at 100~C
and a Brookfield viscosity of no greater than 10 000 centipoise at ~0~C.

An advantage of this invention is that the transmission fluid produced does not derive siy"ili~,lL killellldLic viscosity from high molecular weight polymeric viscosily modifiers.

DETAILE{) DESCRIPTION OF THE INVENTION

The invention relates to a combination which uniquely produces a L,c,l~l,lission fluid with Brookfield viscosities of less than 10 000 cP, and insome cases less than 5 000 cP. In addition these fluids do not co"la;., viscosily modifying amounts of high molecular weight polymeric viscosily modifiers. That is they do not derive any significant amount (i.e. less than 2, W O ~7/04049 PCT~US96/11681 pre~rcbly less than 1 mm21s (cSt) at 100~C) of their kinematic viscosjLy at 1 00~C from polymeric thickeners.

Natural L~.b~ i~diir.q Oils Natural lubl icaling oils include animal oils (e.g., castor oil and lard oil), petroleum oils, mineral oils, and oils derived from coal or shale. Typically, these oils will have kinemalic viscosilies of from 2.0 mm2~s (cSt) to 8.0 mm21s (cSt) at 1 00~C. More prerer~bly the natural lubricating oil will have a kinen ,alic viscosity at 1 00~C of from about 3.0 and 5.0 mm2Js (cSt).

The ,~referred natural lubricating oil is mineral oil. This incl~ Ps oils that are naphthenic or ,cararrillic in ~I.e"~ical structure. Oils that are refined by conve. ~lio.)al methodology using acid, alkali, and clay or other agents sud~as aluminum chloride, or they may be ekl,aoled oils prodllr~rl for example, by solvent e~,a-,lion with solvents such as phenol, sulfur ~I ~xi~e, furfural, ~icl-lordiell-~l ether, etc. They may be hydrotreated or hydrofined, dcu~Yed by chilling or catalytic procPsses, or hydrocracked. The base oil may be prod~ced from natural crude sources or be composed of isomerized wax "-alerials or resid~ ~es of other, ~rin;. ~y p, u~ssps Typically, the lldlls-~lissio-- fluid will contain from 1 to 80, ~,~e~erdLly from 10 to 7~, more ~r~ferably from 20 to 50 weight ~ e,~nl natural luL,ricdli"y oil.

Svnthetic Lubricatinq Oils The synthetic lubricating oils used in this invention are one of any number of commonly used s~. ,lhelic hyd, OCdl ~o" base oils which include, but are not limited to, polyalphaolefins, alkylated aron,alics, and mixtures ll ,efto Examples of these oils are polymerized and il,le" olymerized olefins (e.g polybutenes, polypropylenes, polypropylene-isobutylene copolymers, poly(1 hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes (e.g dodecylbenzenes, tetradecylbenzenes, dinonyl benzenes, di~2 ethylhexyl)benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated poly~,he- ~ols); alkylated diphenyl ethers and derivatives, analogs and ho",ologs thereof.

W O 97/04049 PCT~US96/11681 Particularly preferred synthetic oils are the polyalphaolefins especially those polyalphaolefins pro~ ce~l by oligomerizing 1-octene and 1-decene.

The synthetic oils used in this invention will typically have kinematic viscosilies of between 2 and 100 mm2Js (cSt) at 1 00~C with the most preferred oils having viscosities in the range of 2 to 6 mm2Js (cSt) at 1 00~C.

Typically the transmission fluid will contain from 2 to 80 weight percent ,ur~rerdbly from 10 to 75 and most preferably from 30 to 60 weight o ,uercel)L of the synthetic lubl ic~ling oil.

Seal Swell Aqents The seal swell agents useful with this invention are esters, alcohols, s~hstihlted sulfolanes or mineral oils that cause swelling of ela:,lG",e,ic "~a~,ials. The ester based seal swellers of this invention would include esters of monobasic and dibasic acids with monoalcohols or esters of polyols with r"Gnobasic acids. Examples of ester type seal swelling agents are~ ;soo~ p~te dioctyl seh~c~te di-isooctyl ~Pi~te dioctyl ~ ll,alale di~exyl phthalate. Alcohol type seal swellers are linear alkyl alcoln~ls of low volatility. Examples of suitable alcohols are decyl alc~l,ol, tridecyl alcohol and tetradecyl alcohol. ~d",~les of substituted sulroh.,es are described in U.S. Patent 4 029 588. Mineral oils useful as seal swellers are typically low viscosity mineral oils with high naphthenic or al c~ lic cc:lllellt. Examples of suitable mineral oils are Exxon Necton-37 (FN 1380) and Exxon Mineral Seal Oil (FN 3200). Typical fluids produced by this invention will contain from about 1 to about 30 weight percent seal sweller.
rrere"t:d .anges of seal sweller are from about 2 to about 20 weight per~ t and most pre:fe" ~d are from about S to about 1~; weight percent.

Non-Wax Gellinq Flow Im~rovers The flow improvers of the current invention are oil sol~hle polymers that modify the crystallization of any wax contained in the lubricaLi"g oil so that "gelling" of the lubricating oil is prevented and viscosity increase at lowtemperature is minimized. Thus for the purposes of this ~iiscllcsion the expression "non-wax gelling flow improver" refers to a polymer that lowers the ~0~C E3rookfield viscosity of a wax-containing lubricant. To dete""i..e W O 97/04049 PCT~US96/11681 whether a polymer is a non-wax gelling flow improver, 1.0 mass percent of the polymer is added to a wax~onlai- ,i"y lubricant blend. The 40~C
Brookfield viscosilies of the lub,icar,t with and without the flow improver are then measured. For a polymer to be a non-wax gelling flow improYer, the s ~O"C viscosily of the blend cunl~ 9 the flow improver must be lower than the Cul ~ espo. ~di~ .9 blend without the flow improver.

The non-wax gelling flow improvers act by modifying the size, number, and growth of wax crystals in lulJIi~lill~ oils in such a way as to impart lO improved low te- I ~eralure l lal l-llil l~, pumpability, and or ~rdl lsl, ~issio~ I
operability. There are two co~ on types of polymers used as flow improvers --one derives its activity from the backbone, the other from the sidechain.

The active ~acl~L~one variety, such as ethylene-vinyl ~-et~te (EVA) co polymers, have various lengths of methylene seyl"e.,ls rat.do~,ly distributed in the bac.ht,G"e of the polymer. These ethylenic se~llle-lls, which ~sso~:~'e or co-crysP~ e with the wax crystals, inhibit further crystal growth due to ~,a"e.l ,es and non-cryst~ hle sey"~e"ls in the polymer.

The active sidechai" type polymers, which are the preferred flow improvers for this invention, have methylene se~",el,ls in the side chains, p~efer~ly normal alkyl groups. These polymers work similarly to the active backbone type except the side chains have been found to be more effective in treating isGt~ rri"S as well as n~ ardrri~ Is found in luLJI icalir ~y oils.
Represe"lalive of this type of polymer are Cg to C18 dialkylfl""~rale vinyl ~cet~e copolymers, polyacrylates, polymethacrylates, and esterified styrene-maleic anhydride copolymers.

While the polyacrylates, polymethacrylates, and styrene-maleic anhydrides may function as viscosity modifiers (i.e., polymeric composiliG"s used to increase the viscosity index of lubricating co" "uositions), it is appreci~tP~ by those skilled in the art that these comrositions also function as flow improvers de,uending on their molecular weight and treat rate. Thus, for the purposes of this invention, non-wax gelling flow improvers include polyacrylates, polymethacrylates, and styrene-maleic anhydrides having average molecul~r weights no greater than ~00,000 atomic mass units as determined, for example, by gel permeation c:l "-o" ,alograpl ,~. The term "atomic mass unit" is a measure of atomic mass defined as 1t12 the mass of a ca.LJot. atom of mass 12.

Typically, products of this invention will contai- ~ from 0.05 to about 2.0 weight percent flow improver. ~rerer- ed co- ~ce- ~ Lions of flow improvers are from about 0.1 to about 2.0 weight percent and most ~lererltd are from about 0.2 to about 2.0 weight percent.

Friction Modifiers A wide variety of friction modifiers may be employed in the present invention includfng the following:

(i) Alkoxylated Amines Alkoxylated amines are a particularly suitable type of friction ",~.lilier for use in this invention These types of friction modifiers may be sele~e~
from the group consisting of (I), (Il), and mixtures thereof, where (I) and (Il)are:

lR6 R (R3~)nH
Rl - (X)m - R2 N\ (I) (R40)nH

and lR6 R (R30)nH
Rl ~ (X)m ~ R2 ~ N - Rg - N (II) ~0 (Rs0)nH (R40)nH

where:

R is H or CH3;

W O 97/04049 PCT~US96/11681 R1 is a Cg-C2g saturated or unsaturated, substituted or unsubstituted, a~ hdLiC hydl O~dl b~rl radical, ,~rerel dbly C 1 0-C20, most ~.-erera61y C14-C18;
R2 is a straight or branched chain C1-C6 alkylene radical, ~rereraLly C2-C3;
R3, R4, and Rs are independently the same or different, straight or branched chain C2-Cs alkylene radical, preferably C2-C4;
R6, R7, and R8 are independently H or CH3;
Rg is a :,llai.Jhl or bfancl~ed chain C1-Cs alkylene radical, ~rerer~bly C2-C3;
X is oxygen or sulfur, ~lererdbly oxygen; m is 0 or 1, preferably 1; and n is an integer, independently 14, "~rel~bly 1.

In a particularly preferled el"bocli",elll, this type of friction modifier is 15 ~,dra~,lel i ed by formula (I) where X represents oxygen, R and R1 co"lain a combined total of 18 carbon atoms, R2 represents a C3 alkylene IddiC~I, R3 and R4 represent C2 alkylene radicals, R6 and R7 are h~dlu~ells, m is 1, and each n is 1. P~efelled amine coll".ounds conlai" a cc",bil,ed total of from about 18 to about 30 carbon atoms.

rl~a,~lion of the amine compounds, when X is oxygen and m is 1, is, for example, by a multi-step p.ucess where an alkanol is first re~ctP-l in the presence of a catalyst, with an unsaturated nitrile such as acrylonitrile to form an ether nitrile inLer"~ediate. The intermediate is then hydrogenated, ,~eferaL,ly in the presence of a convenliol ~al h~droge"ation catalyst, such as platinum black or Raney nickel, to form an ether amine. The ether amine is then reacted with an alkylene oxide, such as ethylene oxide, in the presence of an alkaline catalyst by a conventional method at a temperature in the range of about 90-1 50~C.

Another method of preparing the amine compounds, when X is oxygen and m is 1, is to react a fatty acid with a~"~o,.ia or an alkanol amine, such asethanolamine, to form an intermediate which can be further oxyalkylated by reaction with an alkylene oxide, such as ethylene oxide or propylene oxide A process of this type is discussed in, for example, U.S. Patent No 4,201 ,684.

W O 97/04049 PCT~US96/11681 When X is sulfur and m is 1, the amine ~riction modifying compounds can be formed, for exampte, by effecting a convenlional free radical reaction between a long chain alpha-olefin with a hydroxyalkyl mer~arl~ such as beta-hydroxyethyl mer~plan, to produr e a long chain alkyl hydroxyalkyl sulfide. The long chain alkyl hydroxyalkyl sulfide is then mixed with thionyl chloride at a low temperature and then heated to about 40~C to form a long chain alkyl chloroalkyl sulfide. The long chain alkyl chloroalkyl sulfide is then czllse~ to react with a dialkanolamine, such as diethanolamine, and, if desired, with an alkylene oxide, such as ethylene oxide, in the presence of an lO alkaline catalyst and at a temperature near 100~C to form the desired amine ~,.",ounds. Processes of this type are known in the art and are ~isc~ssecl in, for example, U.S. Patent No. 3,70~,139.

In cases when X is oxygen and m is 1, the present amine r.ic,lio 15 modifiers are well known in the art and are described in, for example, U.S.
Patent Nos. 3,186,946, 4,170,560, 4,231,883, 4,409,000 and 3,711,406.

Examples of suitable amine co"~ounds include, but are not limited to, the following:

N, N-bis(2-hydroxyethyl)-n-dodecylamine;
N,N-bis(2-hydroxyethyl)-1 -methyl-t- idec~"~lamine;
N,N-bis(2-hydroxyethyl)-hP~ cylamine;
N,N-bis(2-hydroxyethyl)-oct~iPcylamine;
N,N-bis(2-hydroxyethyl)~ ecenylamine;
N,N-bis(2-hydroxyethyl)-oleylamine;
N, N-bis(2-hydroxyethyl)-stearylamine;
N, N-bis(2-hydroxyethyl)-undecylamine;
N-(2-hydroxyethyl)-N-(hydroxyethoxyethyl)-n-dodecylamine;
N,N-bis(2-hydroxyethyl)-1-methyl-undecylamine;
N,N-bis(2-hydroxyethoxyethoxyethyl)-1 ~thyl~ctadecylamine;
N, N-bis(2-hydroxyethyl )~ocoa, . ,i. ,e;
N, N-bis(2-hydroxyethyl)-tallowamine;
N,N-bis(2-hydroxyethyl)-n-dodecyloxyethylamine;
N,N-bis(2-hydroxyethyl)-lauryloxyethylamine;
N,N-bis(2-hydroxyethyl)-stearyloxyethylamine;
N, N-bis(2-hydroxyethyl)-dodecylthioethylamine;
N,N-bis(2-hydroxyethyl)~odeoylthiopropylamine;

W O 97/04049 PCT~US96/11681 g N, N-bis(2-hydroxyethyl)-hexadecyloxypropylamine;
N,N-bis(2-hydroxyethyl)-hexadecylthioptu~ylamine;
N-2-hydroxyethyl, N-[N', N'-bis(2-hydroxyethyl ) ethylamine~-oct~decylamine; and s N-2-hydro~yethyl, N-~N', N'-bis(2-hydroxyethyl) ethylamine3 -stearyla. "ine.

The most prefer~ ~d additive is N,N-bis(2-hydroxyethyl)-hex~decyloxypropylamine. This additive is available from Tomah CGIII~an~r o under the desiyl)ation Tomah E-22-S-2.

The amine's hydrocarbyl chain length, the saturation of the hydrù~-byl chain, and the length and position of the polyoxyalkylene chains can be varied to suit specific requirements. For example, increasing the s number of carbon atoms in the hyd-oca-l,yl radical tends to increase the amine's melting ~e..,~eral--re and oil solubility, however, if the h~1d-ùcalL,~lradical is too long, the amine will cryst~ e from sollJtion. Decreasing the degree of saturation in the hyd- ~ca, I~yl radical, at the same carbon ~- .lel .l of the hyd- uca- L,yl chain, tends to reduce the melting point of the amine.
Increasing the amount of alkylene oxide, to lenylhe.. the polyoxyalkylen chains, tends to ir~ease the amine's water solubility and decrease its oil solubility.

The amine cc.."~ounds may be used as such. However, they may also 25 be used in the form of an ~ rt or reaction product with a boron compound, such as a boric oxide, a boron halide, a met~bor~le, boric acid, or a mono-, di-, and trialkyl borate. Such ~ ~s or derivatives may be illustrated, for e~cd."ple, by the following structural formula:

R (R30)n\
n Rl ~ (X) m ~ R2-N\ B-O-RlO
(R40)n where R, R1, R2, R3, R4, X, m, and n are the same as previously defined and where R10 is either hydrogen or an alkyl radical.

w 097/04049 PCTAUS96/11681 (ii) Carboxyiic Acids/Anhydrides with Polya"~i"es A second type of friction modifier useful with this invention is the reaction product of a polyamine and a call,~xylic acid or anhydride. Briefly, the polyamine reactant co"lai. ,s from 2 to 60 total carbon atoms and from 3 to 15 nilloge" atoms with at least one of the nitrogen atoms ~ .-esenL in the form of a ~.i..,a,y amine group and at least two of the ,e."ai"i.,g llillo~ell atoms presel.l in the form of primary or seconda-~ amine groups. Non-limiting o eAa".~les of s~it~hle amine ccl"~ounds include: polyethylene a.~i"es such as diethylene l.id,.,i"e (DETA); triethylene tel~ e (TETA); telraell.~/lene pe..la..,i.,e (TEPA); polypropylene amines such as di-(1 2-propylene)l,id",;"e, di(1 3-propylene) triamine and mixtures thereof. Additional s~it~hle ar";nes include polyoxyalkylene polyamines such as polyoxypropylene llialllilles and polyoxyethylene l,ia-";nes. r~e~l.ed amines include DETA TETA TEPA
and mixtures thereof (PAM). The most preferred a"~ es are TETA TEPA
and PAM.

The c~-bu~lic acid or anhydride reactant of the above l~éicli product is ~;I,a,a~;le,i~ed by formula (Ill) (IV) (V) (Vl) and mixtures ll,~lec.~.

O o o R C OH (III); R ~ O C R (IV) R ~ J1 R
l~",o (V); and C 8HH (VI) o ~o where R is a sl,ais~ l or branched chain saturated or unsaturated, ali~l.dlic 2S hy-lr~:lca-b~l radical contail lil Ig from 9 to 29 carbon atoms pre~erably from 11 to 23. When R" is a branched chain group no more than 25% of the carbon atoms are in side chain or pendent groups. R is preferably straight chained.

W O 97/04049 PCT~US96/11681 The R" hydrocal byl group incl~ ~IPS pre~Jomil Idl Illr hy~.~n~Cal byl 9rQUpS
as well as purely hy-llo~lL~yl groups. The descliplion of these groups as predol)li, .a, Illy hydrocarbyl means that they contain no non-hydrocarbyl sllhstituents or non~,LGn atoms that significantly affect the hydlocalb~l ~;1 laraclel i~ s or properties of such groups relevant to their uses as clesc;~ ed here. For ex~lll,ùle, a purely hydrocalt,~l C20 alkyl group and a C20 alkyl group s~ ~bstit~ ~te~ with a methoxy substituent are s~ sl~ lli811y simiiar in their properties and would be considered hydrocarbyl within the conl~t of this disclosure.

Non-limiting examples of s~ ~hstit~ents that do not si~~, lir.c~, ILly alter theh~d~oc~. b~l cl la, c,cLerislics or p- ope, lies of the general nature of the hydl o~a. byl groups of the ca. boxylic acid or anhydride are:

lS Ether groups (esper;~lly hyd~ uca. L~yloxy such as pl ~~, ~oxy, benzyloxy,o,sy, n-isotoxy, etc., particularly alkoxy groups of up to ten carbon atoms);
Oxo groups (e.g., -O- linkages in the main carbon chain);

Ester groups (e.g.. _B_o-h~ uca- L yl);
o Il Sulfonyl groups (e.g., - S - h~chuca.byl); and B

Sulfinyl groups (e.g., - S - h~ù~lbyl).
o ~ hese types of flicliGIl modifiers can be formed by reacting, at a te,.-pe~a~ure from about 120 to 250~C, at least one polyamine and one ca, uùxylic acid or anhydride in proportions of about 2 to 10 molar equivalents of carboxylic acid or anhydride per mole of amine reactant.

W O 97/04049 PCT~US96/11681 (iii) Other Friction Modifiers o~ Gnallyl other friction modifiers may be used either alone or in c~sml~i"dlion with the foregoing desc~ibed friction ~ouirierc7 to achieve the desir~..l fluid pe,~ull,~a"ce. Among these are esters of calLo,cylic acids and anhydrides with alkanols. Other conventional friction modifiers ue"e.~lly consi .l of a polar te"l~i-,al group (carboxyl, hydroxyl, amino, etc.) covalently bonded to an oleophilic hydro~. lJ~I, chain.

Particularly ~urerel~ed esters of c~,l,oxylic acids and anhydrides with alkanols are des-a ibed in, for example, U.S. Patent 4,702,850. This r~:~rel,ce teaches the usefulness of these esters as r,i. Lio" Il,udilier:,, particularly the esters of succinic acids or anhydrides with thio-bis-alkanols, most particularly with esters of 2~u~JPcenyl succinic anhydride and thiodiglycol.

Examples of other conv~l~liG,~al friction modifiers (i.e., polar terminal group + oleophilic hydroca-~u-l chain) are des~ibed by, for ekai..,~le, M.
Belzer in the "Journai of Tribology" (1992), Vol. 114, pp. 675~82 and M.
Belzer and S. ~lal,dlll"ir in "Lubrication Science" (1988), Vol. 1, pp. 3-26.

Typically the f i-,liun modifiers will be ~ senl in finished lldllslllissiu,, fluid co,ll~osilion in an amount between 0.01 to 5, ~rl:rel~L~ly 0.1 to 3 weightper ,enl.

Other Additives Other additives known in the art may be added to the transll,issio., fluid. These additives include dispersants, antiwear agents, antioxidants, 30 CC~I I uSiGI I inhibitors, detergents, extreme pressure additives, and the like.
They are typically fisclose~l in, for example, "LL-LIicallL Additives" by C. V.
Smalheer and R. Kennedy Smith, 1~67, pp. 1-11 and U.S. Patent 4,105,571.

Representative amounts of these additives are sl l"",~ ed as follows:

(Broad) (Prefer, ~d) Additive Wt.% Wt.%
Corrosion Inhibitor0.01 - 3 0.02 - 1 Antioxidants O.Q1 - 5 0.2 - 3 Dispel :~dl llS0.10 - 10 2 - 5 A.,liroa",i"g Agents0.001- 1 0.001 - 0.5 Detergents 0.01 - 6 0.01 - 3 o Antiwear Agents 0.001- 5 0.2 - 3 Suitable dispersants include hydl uca, b~l succinimides hyd, ~Cal u~l succi"al l ,i~es mixed ester/a" ~i~les of hydrocarbyl-substituted succinic acid hydroxyesters of h~dl c ca, L~yl-substituted succinic acid and Mannich co"densdlion products of hyd,ocarb~l-substituted phenols formaldehyde and polyamines. Mixtures of such dispersants can also be used.

The prefer, ed disper~anls are the alkenyl succi, li",ides. These include acyclic h~dl ucal b~l substituted succinil ~ es fol l "ed with various a"li"es or amine derivatives such as are widely ~isclose~ in the patent literature. Use of alkenyl succi"i~ides which have been treated with an ino,tJc.,.ic acid of ~ho5p~ lus (or an anhydride thereof) and a bo,u-~ali.,y agent are also suitable for use in the compositions of this invention as they are much more cc",p~liL,le with ela~lo",eric seals made from such s~hs~nces as fluoro-elastomers and silicon~o, ~laini, ~g elaslo,.)er:
Polyisobl~t~nyl succi,-i",ides formed from polyisobutenyl succinic anhydride and an alkylene polyamine such as triethylene tel~",i~e or tetraethylene pe"la" ,i"e wherein the polyisob~ ~tenyl substituent is derived from polyisohutene having a number average molecular weight in the range of 500 to 5000 (~re~erably 800 to 2500) are particularly suitable. Dispersants may be post-treated with many reagents known to those skilled in the art. (see e.g. U.S. Pat. Nos. 3 254 025 3 502 677 and 4 857 214).

Suitable antioxidants are amine-type and phenolic antioxidants.
Examples of the amine-type antioxidants include phenyl alpha napl ,ll ,ylamine phenyl beta , Id~Jhlh ylamine diphenylamine bis- alkylated diphenyl amines (e.g. p p-bis(alkylphenyl)amines wherein the alkyl groups ccn~ain from 8 to 12 carbon atoms each). Phenolic antioxi~ ts include sterically hindered phenols (e.g. 2 6-di-tert-butylphenol 4-methyl-2 6-di-tert-o butylphenol etc.) and bis-phenols (e.g. 4 4'- methylenebis(2 6~i-tert-butylphenol) etc.) and the like.

.
CA 022l7862 l997-lO-30 The additive co.)ce"L,ates of this invention wiil c0lll2ill the vi~cosily modifier friction modifier and other desired additives in a natural andlor synthetic lubricating oii in relative proportions such that by adding the co"ce"l.dle to a larger amount of a suitable natural andlor synthetic oil the resulting fiuid will cont~i, I each of the ingredients in the desired concentration. Thus the cG"ce"l,ate may contain a synthetic oil as the luL,Ii~lill~ oil if the desired final composition contai"s a lesser amount of synthetic oil relative to the mineral oil. The concentrate typically will CGI .lain between 25 to 100 ~,eferdl,ly from 6~ to 95 most preferably from 7~; to 90 weight percent of the viscosily modifier friction modifier other desirad additives and synthetic and/or natural oil.

The following examples are given as specific illustrations of the claimed invention. It should be understood however that the invention is not limited to the specific details set forth in the examples. Although the following exa",plas are ~ire~ed to a~lo",~lic l,d"~mission fluids (ATF), this invention isalso equally arp!i~hl~ to powershift l,~"s",issions manual ll~ issiu,,s hyd. usldlic transmissions continuously variable trans- ~ Iissiol ~s and the like.
All parts and ,~)erce,~layes in the exd,."~les as well as in the re",~i"der of the specification and claims are by weight unless otherwise specified.

Table 1 shows nineteen (19) automatic transmission fluids (BLENDS
1-19) that were produced by blending 8.0 mass percent of an additive ,uackaue devoid of any flow improvers into suitable ATF base oils. The additive package cc nLai. .ed conventional amounts of a succi"i,-,;de dispe, sa"t antioxidants antiwear agents friction modifiers a cc " osic n 30 ir Ihi~ilol, an a, llirodl,lanl and a diluent oil.

Each ATF co-,lai,-ed Exxon solvent 100 neutral oil (~4.0 mm21s (cSt) at 1 00~C) (FN 136~) and PA04 (~4.0 mm2Js (cSt) at 1 00~C) (1 -decene oligomer). The ratio of 100 neutral oil to PAO~ was chosen such that a 35 properly treated blend could achieve a 40~C viscosity of less than 10 000 cP and a kinematic viscosity at 1 00~C of at least 3.8 mm2/s (cSt).
Additionally BLENDS 1-19 contai,-ed diisooctyl adipate as a seal swelling W O 97/04049 PCT~US96/11681 agent. The compositions of the blends and their measure kinematic viscosilies at 1 00~C and Brookfield viscosities at 40~C are shown in Table 1.

The flow improvers used are identifled in Table 1 by their trade names.
s The PARAFLOW~ products are fu" ,ar~te-vinyi acePte copolymers with varying sidechain lengths. The ACRYLOID~) TLA (Texaco) and VISCOPLEX~ products are poly")elhac,ylates of varying molec~ r weights and sidechain lengths.

BLEI'ID 1 in Table 1 is a 'blank' in that it co~lai~ ~s no flow improver. As shown, this blend has a very high ~0~C Brookfield viscosity of 87 000 cP
which is totally unexpected for an ATF containing over 40% of a s~"ll,eiic lubricating oil PAO4. In addition BLENDS 8 and 9 show the results obt~ined when an ineffective flow improver is used. While not wishing to be bound to any particular theory it is believed that the PARAFLOW 394 flow improver used in BLENDS 8 and 9 polymerizes with the wax ~,,esenl in the natural IIJl l ;c~liny oil to form a crosslinlced wax gel which c~ ~ses viscosilies at 40~C higher than those of the 'biank'. However, all of the other '~iow improvers" in Table 1 provide a significant reduction in 40~C Br~Jokr,~ld viscosiL~r relative to the 'blank'. As shown some flow improvers are more effective than others; compare BLENDS 4 and 10 both at 1.00 percent treat rate and BLENDS 3 and 5 both at 0.25 percent treat with essentially ec~ual kine,~,alic viscosities at 100~C. Thus Table 1 demonsllaLes the dra",alic effect that certain flow improvers specifically the non-wax gelling flow improvers of this invention can have on the 40~C Brookfield viscosity of partial synthetic ATF's.

E)CAMPLE 2 Fluid viscosity at 10~C is not only a function of fiow improver type but also flow improver conce~r~lion. Table 2 shows a series of blends using three effective flow improvers for this system. Table 2 shows that for each flow improver there is an optimum treat rate to obtain the lowest 40~C
Brookfield viscosity (see BLENDS 23 27 and 31). While not wishing to be 3S bound to any particular theory it is believed that this result occurs heG~l~sç
there is not enou~h flow improver at very low conce~ lion to disrupt cryst~ tion of ail the wax and consequently the Brookfield viscosities are elevated compared to the minimum Brookfield viscosity obtainable in these CA 022l7862 l997-lO-30 systems (see BLENDS 24 28 29 and 34). It is also believed that at concer.llatiGns that are too high the flow improver merely adds viscosity at 10~C since the flow improver is itself a polymer (see BLENDS 21 26 and 30). Therefore for each ATF system the type and concentration of the most effective flow improver must be determined.

Table 3 shows a number of ATF blends made using the Exxon solvent 10 100 neutral oil that produce fluids that completely meet very stringent tan;,ets, i.e. kinematic viscosity at 1 00~C of no less than 3.8 mm21s (cSt) and Brookfield viscosities at 10~C less than 5 000 cP. BLENDS 37 39 42, 43 44 45 and 46 fully meet these stringent requirements this is only possihle due to the incorporation of non-wax gelling flow improvers.
lS

The cor~positions of this invention work in a variety of lubricating oils.
Table 4 shows blends meeting the ~ll i- Iyen~ requirements des~ ibe.l in 20 Example 3 but with various natural l~ i~Lin~ oils: Exxon 100 neutral (~4.0 mm2/s (cSt) at 1 00~C); Exxon 75 neutral (~3.0 mm2Js ~cSt) at 1 00~C);
Chevron RLOP 100 neutral--a severely hyd,~l,ealed and catalytically de-waxed h~sestock having a kine,..alic viscosi~y of ~4.1 mm2Js (cSt) at 100~C;
and Imperial MXT-5 -- a basestock produced by isomerizing slack wax having a kinematic viscosity of ~3.8 mm2/s (cSt) at 100~C. In each case the c~ osilion was evaluated without a flow improver BLENDS 47, 52, 56, 60 and all show the unexpectedly high 40~C Brookfield viscosilies exhiL)ile~ by mixtures of mineral oiis and synthetics without flow improvers. Table 4 shows that any of these natural lubricating oils when treated with sy, Ill l~lic c~"~o"enLs and flow improvers can be made to meet the most restrictive requirements of high and low temperature visco",et,ics. This is exe"",litied by BLENDS 49 51 53 55 57 59 61 and 63 all of which have ki"e."dlic viscosi~ies at 1 00~C of at least 3.8 mm2/s (cSt) and Brookfield viscosities at -40~C under 5 000 cP.

The results in Tables 1 - 4 are unexpected. One skilled in the art would expect that treating a natural lubricating oil based ATF having a -40~C
Brookfield viscosity of 20 000 cP with a synthetic lubricating oil having a -_ 1 7 _ -40~C Brookfield viscosily of 2 000 cP to simply produce a fluid with a viscosity in between. HoweYer we have found that the effect of the cc "tai"i, -g wax in the natural lubricating oil overcomes the beneficial effects of the synthetic lubricaLing oil and the wax must be treated with a non~elling flow improver to obtain all of the expected benefits of a blend containing synthetic luL"icali"~a oils (partial synll,elic). It is evident even in blends c~"laining only about 25% mineral luLIicalill9 oil (BLEND 47) that the untreated wax has a very large negative impact on BrookFleld viscosity at -40~C.

The ~u,i,,c.~.~les pler~lled emLodi"~e"l~ and modes of operation of this invention have been described in the foregoing specification. However, the invention which is intended to be prot~cted herein is not to be construed as limited to the particular forms ciisclosed since these are to be regarded as 5 illustrative rather than restrictive. Variations and cl,anges may be made by those skilled in the art without CJepdl til l!J from the spirit of the invention.

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Claims

CLAIMS:

1. An transmission fluid composition comprising (a) a natural lubricating oil having a kinematic viscosity from 2.0 to 8.0 mm2/s at 100°C;

(b) a synthetic lubricating oil having a kinematic viscosity from 2 to 100 mm2/s at 100°C;

(c) a seal swelling agent;

(d) 0.001 to 5.0 weight percent of a friction modifier, and (e) 0.05 to 2.0 weight percent of a non-wax gelling flow improver, providing the fluid has a kinematic viscosity of at least 3.8 mm2/s at 100°C
and a Brookfield viscosity of no greater than 10,000 centipoise at -40°C.

2. The composition of claim 1 where the synthetic oil is poly-alpha-olefin-, monoester-, diester-, polyolester-based oil, or mixtures thereof.

3. The composition of claim 2 where the oil is a mixture of mineral oil and poly-alpha-olefin.

4. The composition of claim 3, where the flow improver is selected from the group consisting of C8 to C18 dialkylfumarate vinyl acetate copolymers, polymethacrylates, polyacrylates, styrene-maleic anhydride copolymers, and their mixtures.

5. The composition of claim 4, wherein the friction modifier is selected from the group consisting of (I); (II); reaction products of polyamineswith (III), (IV), (V), (VI); and mixtures thereof, where (I), (II), (III), (IV), (V), (VI) are:

(I) and (II) (III); (IV);

(V); and (VI) where:

R is H or CH3;
R1 is a C8-C28 saturated or unsaturated, substituted or unsubstituted, aliphatic hydrocarbyl radical, R2 is a straight or branched chain C1-C6 alkylene radical;
R3, R4 and R5 are independently the same or different straight or branched chain C2-C5 alkylene radical;
R6, R7 and R8 are independently H or CH3;
R9 is a straight or branched chain C1-C5 alkylene radical;

X is oxygen or sulfur;
m is 0 or 1;
n is an integer, independently 1-4; and R" is a straight or branched chain, saturated or unsaturated, aliphatic hydrocarbyl radical containing from 9 to 29 carbon atoms with the proviso that when R" is a branched chain group, no more than 25% of the carbon atoms are in side chain or pendent groups.

6. The composition of claim 5, where the friction modifier is an ethoxylated amine, alkyl amide, or mixtures thereof.

7. The composition of claim 6, where the composition further comprises a borated or non-borated succinimide dispersant, a phenolic or amine antitoxidant, such that the sum of the dispersamt, antioxidant, and friction modifier is between 2.0 to 11 weight percent of the composition.

8. The composition of claim 1, wherein said composition is an automatic transmission fluid.

9. A method for producing the composition of claim 1 comprising the steps of:

(a) providing a major amount of the natural and synthetic lubricating oil; and (b) adding to the lubricating oil the flow improver, seal swelling agent, and 0.01 to 5.0 weight percent of the friction modifier.