CA1261611A - Oil-in-alcohol microemulsions in antifreeze - Google Patents

Abstract

OIL-IN-ALCOHOL MICROEMULSIONS
IN ANTIFREEZE

Abstract Oil-in-alcohol microemulsion-containing composition concentrate stabilized by at least one emulsifer and containing at least one organic hydrophobizing agent having a metal adsorbing moiety therein. The composition concentrate, when diluted with water, is useful in automotive coolant systems as an antifreeze.

Description

- 1 ~;26~
OIL-IN-ALCOHOL MICROEMULSIONS
- IN ANTIFREEZE
Cross-Reference to Related APplications This application is related to the subject matter of co-pending Canadlan application Serial No. 477284-9, filed nn March 22, 1985, and to concurrently flled Canadian application Serial No. 485899-9, filed June 28, 1985.
Field of the Invention The present lnvention relates generally to a microemulsion-containing antifreeze composition concentrate, and more particularly to such a concentrate containing an oil-in-alcohol microemulsion.
Back~round of the Invent on Microemulsions for use in antifreezes are well known in the art. For example, ethylene glycol antifreeze compositions containing mineral oil plus an emulsifier or containing a barium sulfonate oil are well-known and were used commercially in automobiles up until the mid-1960's. The oil in these antifreezes provided excellent corrosion inhibition for the antifreezes by coating the metal surfaces of the coolant system with a so-called "magnetic film". However, in concentrate form, these emulsions are generally phase stable only for a very short period of time of perhaps a couple of days or less, after which time they tend to separate into two phases.
With the ad~ent of antifreeze overflow-tanks used to hold the volume expansion of

- 2 ~

~nti~reeze in ~ hot engine cool~nt system, these r~ther unstable m~croemulsion ~ntifreezes were replaced with other types of Rntifreezes, since a mscroscoplc ~wo-ph~se ~ntifreeze tends to congreg~te the less dense oil ph~se in the overflow-tank ~nd the second ph~se in other p~rts of the cooling system. For the ~bove described re~sons, m~croscopic two-phase ~ntifreezes ~re obsolete snd current antifreezes ~re ~ingle ph~se, most notAbly the sllicone-sillc~te st~bilized ~ntifreezes dlsclosed in U.S. P~tents 3,337,496 ~nd 3,341,469.
In recent years, microemulsions h~Ye been developed which are known for their long term stor~ge st~bility, l.e. their ability to maint~ln ~n ~pparent single ph~se over ~n extended period of time. By w~y of illustr~tion, oil-in-water microemulsions and wster-in-oil microemu~sions are extensively employed ln the hydraulic fluid fleld.
For example, U.S. Patent 4,337,}61 discloses oil-in-w~ter microemulsions whereas U.S. P~tent 4,371,44J discloses wster-ih-oil microemulsions for use ~n hydr~ulic fl~lds, and the like.
Microemulsions, v~riously referred to as micellar solutions, "soluble oi~s", swollen micelles~ etc., have been extensively discussed in the litereture. See, for exHmple, Microemulsions, I. D. Robb, Edltor, Plenum Press (1981); ~nd, Microemulsions Theorv ~nd Pr~ctlce, L.M. Prince, Editor, Ac~demic Press (1977). Microe~ulslons ~re typic~lly ch~r~cterized ~s cle~r, bright cnd tr~nsparent (~nd, hence, ~pp~rently homogeneous ~nd microdispersed, whereas mflcroemulsions ~re visibly

- 3 ~ 6~

turbid ~nd two-phase. These charac~eristics are due ~o ~he f~ct th~t ~he p~rtiole Si.e. micro-droplet~
in 8 microemulsion ls typically sm~llel th~n the wave-length of visible li~ht. Although cle~r t~ the eye, the presence of the mlcrQemulslon partlcules can be detected by instrument~l light-scattering techniques.
As used hereln, ~he ~erm "microemulsion" is used in its broadest sense to encompass faintly turbid or op~lescent composition us well AS
completely clear ones. All of these various types of mioroemulsions ~re charscterized by exccllent amb~ent ~emper~ture storage s~ability ~nd particle sizes of ,~bout less than 0.1 micron. In contrast, mAcroemulsions ~re turbid in appear~nce (e.g., cow's milk) and tend to ph~se sep~r~te upon standing ~t amblent temperature.
Heretofore, microemulsions ln &nti~reeze~
as discus~ed ~bove, were not known in the art to the best of our knowledge. We speculate th~t there ~re at least two reasons ~or this ~bsence. First, if ~he ~ntifreeze ~ngredients are in stable, micr~emulsion form, there is a problem ~s to how these ingredients will be made avail&ble to protect the metal surf~ces of the c~r's coolant system.
Second, ~ fo~ming problem is frequent~y encountered when using the hi~h levels of emulsifier required to make a st~ble microemulsion. Such e fosming problem would be detrlment~l to ~ c~r~s coolant system.
Obiect of the In~ention It ls the ob3ect of the present invention to provlde ~n antifreeze composltlon concentr~te ch~racterized by ~dv~nta~eous storsge st~bility snd, D-1426~-1 .
.

~ 4 ~ ~ 6 ~
upon dilution9 providing an ~ntifreeze th~t is microdisp~rsed and ~pp~rently homogeneous ~t ~mbient ~low~ temper~ture and pre~erably two-phQse ~t RutomOtive engine oper~eing (higher) temper~ture.
Thls and other ob~ects will become ~pp~rent from ~ reading of the followlng det~lled spec~fication.
Summ~rY of the_Invention In one aspect, the present invention relates to ~n oil~ln-Alcohol microemulsion-containing antifreeze composition concentr~te having ~ discontinuous phase ~nd ~ continuous ph~se comprising:
~ a) ~t least one slcohol, in ~r, ~mount sufficient to form a contlnuous ph~se ln the concentrate;
(b) alcohol insoluble oil particles forming ~ dlscontinuous ph~se in said composition, s~id p~rticles having 8 p~rticle size less th~n about 0.1 micron (prefer~bly less th~n ~bout 0.05);
~ c) et le~st one surf~ce hydrophoblzing compound selected from the group consisting of org~nic deriv~tives of the follow1ng: phosphate, sulfate, phosphonate, sulfon~te, c~rboxylate, org~noammonlum and phosphonium salts, ~mine oxides, amphoteric and zwitterlonic groups such as bet~ines and sulfobet~ines and mixtures thereof; wherein the organic group ls selected ~rom the cl~ss consisting of th~ following r~dlc~ls: ~lXyl, alkenyl, alkynyl, Rryl, alkylAryl, arylalkyl, ~lkyleneoxy, poly~lkyleneoxy, ~nd combin~t~ons thereof.

- 5 - ~ Z~

The ~bove ~ntifreeze eoncentr~te csn ~ddition~lly option~lly contain:
(d~ ~t least one emulsifler ~present in ~n ~mount sufficient to ~t~blllze the com~position, s~id emulsifler preferably provlding ~ cloud point for the ~ntifreeze st between 40C ~nd 125DC.
In ~nother aspect, the present invention relates to ~n ~ntifreeze composltion. The ~ntlfreeze composition can be made from the composition concentr~te by dllution of the concentr~te with water ~ndlor alcohol at the use site.
In yet ~nother ~spect, the present invention encomp~sses methods for m~king the ~bove ~n~ifreeze composition, either by direct ~ddltion of the oil-ln-alcohol microemulsion to water andlor ~lcohol, or by ~dding w~ter ~nd/or slcohol to the oll-in-alcohol microemulslon, or by pre-forming the composition concentrste.
Deteiled Descrlption of the Inventlon The compos~tlons of the present invention ~re ch~r~cterlzed by long term conc~ntrate stor~ge stabillty, ~s well ~s ~ vlsu~lly single-ph~se ch~r~cteristic ~t ~mbient (low) temper~ture ~nd either ~ visu311y two-phase or mlcrodispersed ch~r~cteristlc ~t oper~ting engine (hlgher) temper~tures in the ~utomob~le cool~nt systems (herein~fter ~lso c~lled "cooling systems"). The concentrste s~or~ge st~bility provides good "shelf-life" for the sntifreeze concen~r~te during w~rehouslng, bulk dlspenslng~ ~nd whlle on store shelves. The microdispersed, Rpp~rently homogeneous - 6 ~ ~

ch~racteristic ~t ~mbient temper~ture m~kes lt possible for the ~utomotive "cooling ~ystem"
(hereinefter also referred to ~s "cool~nt system") overflow-t~nk to con~in a uniform composltlon of ~ll sf the utilized Qntifree2e ingredients, thereby ~voiding the congregation problems of the prior ~rt mscroemulslon-contalning ~ntifreezes when using an overflow t~nk. The two-phase high temper~t~re characterist~c of the sntifreezes of the present invention facilltates the co~ting of the met~l ~urf~ces of the automotive cool~nt system with ~t le~st ~ part of the oil port1on of the microemulsion, thereby sffording the s~me excellent corrosion inhibitl on characteristics for these me~sl surf~ces ~s was ~fforded by the prior ~rt macroemulsion-cont~lning antlfreezes. However, unlike the latter, the composlt10ns of ~his inventlon can be used in the modern automobile coolant systems h~ving ~ overflow holding tank while m~lnt~inlng a uniform dlstrlbution of the rem~ining portlon of oil in the antifreeze cool~nt system, including the holding t~nk. In Another ~spect, the presence of hydrophobizer in the presen~ composition enh~nces the ~fflnity of the oll component for the met~l ~urfaces, thereby enabling even the mlcrodispersed oll in the microemulsion to provlde corrosion proeectlon.
The oll useful in the present inventlon csn be ~ny m~teri~l known as ~n "oll", i.e. ~ny of the numerous ~ubst~nces that are li~u~d or e~sily liquifisble by w~rmlng and ~re "pr~ctically lnsoluble" ln the contlnuous ph~se of the present D-14268-l - 7 - ~L263~
composition, c~n be employed 8S the bas1s of ~he oil ph~se.
As used herein, the term "contlnuous" or "outer" ph~se me~ns the Rlcohol phase that extends through 811 p~rts of the mlcroemulsion in ~
continuous f~shion. This outer ph~se ~s to be distingulshed from the pArtlcul~te, discont~nuous, inner oil ph~se. As is well recognized, the m~ximum packing fr~ction of uniform spheres would m~ke it possible for the outer ph~se to be as smsll in amount ~s 26 vol. ~ b~sed upon the total volume of both phases (which is ~bout the same on ~ welght ba`s~s). Preferably, the outsr Alcohol phase comprises ~t le~st 50 w~. % (more prefer~bly at least 90 wt. ~) bRsed upon the totsl weight of both phases.
As used herein, the term "pr~ctic~lly insoluble" means that the ~mount of oil present exceeds t~e ordin~ry solubility limit of the oil in the contlnuous phase of the composition ~t ~mbient temper~ture.
The oil useful in the present invention msy be obt~ined from ~ wide v~rlety of sources, including ~uch diverse sources ~s ~nimal, veget&ble, miner~l or synthetic m~nuf~cture. Moreover, the composition of ~he oil is ~lso not criticfll, ~nd it m~y be composed of such diverse m~terials ~s predomin&ntly hydrocarbons, such ~s miner~l ~nd petroleum olls, f~tty ~cl~ esters, f~ts, sil~cone oils, polyalkylene oxides ~nd ester deriv~tlves thereof, or mixtures thereof, ~nd the like. The oil phese c~n ~lso cont~ln one or more ~ddi~clves used to D-1~268-1 imp~rt cert~ln properties to the microemulsion, such ~s blocldes, oxid~tion inhibltors, corroslon lnhibitors, Rnd ~he like.
Based upon the ~bove, the term "oil" is intended to include, but is not in~ended to be limited to, ~ny or~nic compound which is practic~lly insoluble in ~lcohol such ~s ethylene glycol or propylene glycol, or mixtures:thereo~, but which c~n be emulsified by the use of ~t least one surf~c~nt. Such oils include non-pol~r and parti~lly pol~r, ~liph~tlc and ~rom~tlc m~teri~l , such as mlneral o$1, paraffln oil, veget~ble oil, n~phtha oll, petroleum b~se oll, mixed xylenes, kerosene, miner~1 spirlt, transformer oil, fuel oil, silicone oil, sll~ne esters, synthetic oil, h~logen~ted ~ils, polypropylene glycols, propylene ox~de/ethylene ox~de copolymers, propylene oxide/butyl~ne oxide copolymers, ethylene oxide/butylene oxide copolymers, ethylene oxide/propylene oxidelbutylene oxide terpolymers, ~s well ~s sulf~ted, sulfonAted, ~hosphated snd phosphonsted oils, h~gher ~lcohols ~nd esters thereof, And the like.
The ~mount of oil present in the microemulsions of ~he present lnvent~on c~n v~ry over ~ wide r~nge, but is prefer~bly between ~bout 0.001 to Rbout 5 (more prefer~bly between sbout 0.1 ~nd about 3) wt. percen~ bQsed upon ~he tot~l weight of the microemulsion. Within the ~bove-specified preferred r~nges, ~he ~mount of oil used ln the mlcroemulslon is dependent upon the p~rticul~r ~ntlfreeze end use required for the microemulslon.

Below ~bout 0.001 wt perc2nt, ~he smoun~ of oil would gener~lly be insufflcient to be functlon~l, where~s above ~bout ~ weight percent ~he ~nt~freeze m~y not s~isfy governmen~l freezing polnk depresslon specificAtions for ~ntifreeze.
As used herein, the term "hydrophobizing .
~gent'l denotes R compound that is adsorbed by the metal surf~ces of fl cooling system and lmp~rts ~n ~fflnity between the metal surf~ces ~nd oil in the microemulsion. Useful hydrophobizing agents ~re selected ~rom the group consisting of orgflnic derivatlves o$ the following: phosph~te, sulf~te, phosphon~te, suifon)ffte, carboxyl~te, ~mmonium ~nd phosphonium salts, amine oxides, pho~phine oxides, amphoteric ~nd zwitterlonics such as bet~ines and sul~obetsines ~nd mixtures thereo~ wherein the organic group is selected from ~he cl~ss consisting of the following r~dic~ls: ~lkyl, ~lkenyl, ~lkynyl, sryl, all havlng up to Mbout 24 c~rbon ~toms, ~lkyleneoxy, poly~lkyleneoxy, and combin~ions thereof.
Generally ~he organophosphates u~eful in the present invention ~re ldentifled by the structur~l formul~:

o Rl-O-P-O-R3 wh~reln e~ch subst~tuent R~, R2, ~nd R3 is selected from the cl~ss consisting of the following r~dic~ls: hydrogen; ~lkyl, Rryl ~ ~lkenyl ~nd ~Z~

alkynyl, with each of the foregoing havinQ up to about 24 carbon atoms; alkyleneoxy, polyalkyleneoxy; phosphate or polyphosphate or their salts; and combinations thereof; with the proviso that at least one of said substituents is an organic radical within the class listed above or combinations thereof.
The preferred organophosphates have the structural formula identified above wherein at least one R substituent consists of an organic radical containing an alkylene oxide polymer or copDlymer derivative of the form R40(PO)x(EO)y~BD) -, wherein the alkyleneoxide units may be either random or blocked and wherein x ~ y )~ z and x ~ y t Z ~ about 100, and R4 is selected from the class of radicals: hydrogen; alkyl, aryl, alkenyl and alkynyl with the foregoing having up to about 24 carbon atoms; phosphates, polyphosphates and salts thereof, and combinations thereof. These organophosphates preferably have molecular weights below about lO,OCO to insure solubility in the antifreeze composition. Antifreeze compositions incorporating these preferred hydrophobizing agents are the subject of our co pending Canadian application Serial No.
484,363-1, filed June 18, 1985.
Preferred hydrophobizing agents are the organophosphates identified by structural formulae I to III, including the free acids and salts thereof, together with mixtures thereof.

r~

2g~

(I) R~kP (OH)3-k O O
(II) R'[P-O-SPO)w(EO)~]nP-R' OH OH

O O
.. ..
(III) R'P-o-~p-o3mH
OH OH
hereln R' = [RO(PO)x(EO)y] whereln R = H or ~lkyl, ~ryl, alkylaryl or aryl~lkyl h~ving up to 24 carbon ~toms RO = Propylene oxide radicsl EO - Ethylene oxide r~dlc~l x = 0 to 1~0 y z O to 100 k = 1 to 3, w~th the provisio th~t k can be 3 lf at le~st ~ne R' group is removed from the phospha~e ester by hydroly~is prior to, or during, use n = 1 to 100 w ~ O to 100 Z = O ~o 100 ~ - 1 to 10 Within ~ given foruml~ x, ~, w or z gr~up is the ~me or dlfferent number.

- 1 2 - ~6~L6~L

Typicsl useful classes of org~nophosph~tes alling within the groups ldentifled by ætructur~l formulae I through III Above, are identified as f ol lc~ws:
o Example l: RO(Pû)x(EO)yP-OH
OH
Formul~ I wi th k Example 2: RO(PO)x(EO)yP -(EO)y(PO~xt)R
OH
Formul~ I with k c 2 O O
.. .
Ex~mple 30 HO-P-O[(PO)w(EO)z]-O-P-OH
OH OH
Formul~ I I wi tSl n x = O
y = O
R = H

O O O
.. .. i.
Example 4: HO-P-O~ (PO)w(EO)zlP~ (PO~w(EO) z]P-OH
OH OH OH
Formula II with n = 2 ~c ~ O
y c O

R = H

- 13 - ~ 2 O O O
.. .~ ., Example 5: [RO(PO)x(EO)y]P-O-P-O-P-OH
OH OH OH
Formula III with m e 2 Other less preferred hydrophobizers ~re org~nic deriv~tives of: sulfonat~, surh as b~rlum alkyl benzene sulfonste; phospon~te, such as do~ecyl phosphonate; c~rboxylate, such ~s c~rboxylic ~cid gr~fted on poly~lkylene glycol; organo~mmonium salts, such DS cetyltrimethyl~mmonium chloride, etc.
.- ThP ~mount of hydrophobizlng ~gent present in the microemulsion eompositlons vf the presen~
invention can v~ry over a wide range, but is prefer~bly between about O.a01 ~nd ~bout 30 (more preferebly between ~bout 0.005 ~nd ~bout 1~ wt.
percent, based upon the total weight of the microemulsion. Below about 0,001 wt. percent the amount of hydrophobizing egent would generally be insufflcient to be effective, ~here~s above ~bout 30 peroen~, the hydrophobizer is expected ~o provide no further signific~nt hydrophobizing benefits.
Cert~in hydrophobi~ers will perform ~ du~1 role in not only providlng ~n affinity between the engine coolin~ system met~l surfsces and the oll in the microemulsion but ~lso ln acting as an emulsifier for the mlcroemulsion. If the latter role ls not performed by the hydrophobizer, then a separate emulslfier is required.
The emulslflers useful in the present invention lnclude ~ny o~ ~ wide r~nge of ~nionic surf~ot~n~s~ ~uch ~s the org~no-phosphates, D-14268-1 :

- 14 - ~.2~

phosphon~ees~ sulf R tes ~nd sulfonates, ~s well ~s salts of f~tty ac~ds; c~ionic surfact,snes such ~s organosmmonium ~nd phosphonium s~l~s; ~nd non-loni~
surf~ct~nts such ~s ~lkoxyl~ted alcohols, phenols, And sm~nes, ~nd f~tty ~cids, and the llke; and ~mphoteric ~nd zwitterionic groups such ~s bet~ines ~nd sulfobe~lnes, th~t hre well-known ln the art.
Yet another group of surf~ctants useful as emulsifiers would include ~lXyl ~mine oxides, alkyl phosphlne oxides, find the like. CertAin lnorgan~c compounds known to be active dS emulsifiers~ such ~s soluble bor~te ~nd phosphate s~lts, c~n be employed a~ emulsifiers ln the present invention. The ~bove emulsifiers cen be used singly or in combin~tion ~s illustrated in the Examples given below, and R
combination of 2t least two surfact~nts is preferred in order to fscllit~te microemulsiflcation and reduce or mini~ize the totfll emuls~ier requirement. ~lso, water ~n low co~centr~tions is option~lly used to enh~nce the st~bility of the microemulsions, prefer~bly ~n an ~mount o~ less than 10 weight percent bAsed upon the welght o the microemulsion.
Preferably, at le~st one emulsi~ier employed ln the composlt~ons of the present invention provldes the ~ntifreeze with a so-c~lled "cloud point" such th~t the antifreeze exhiblts reverse t~mper~ture solubility, Although ~
compositlon without ~ clvud point is ~lso use~ul.
In gener~ t le~st one emulslfier employed prefer~bly provldes ~ cloud polnt for the antlfreeze ~ between ~bout 40C ~nd about 125~C, more ~L2~6~
prefer~bly between 65C ~nd 125C, most prefer~bly between 65~C and 90C. The lower limlt of 40C ls well ~bove smbien~ temper~ture, whereas ~he upper limit of 125C ls gener~lly below ~u~omotive engine temper~tures. The existence of this cloud point m~kes lt possible for the emulsifler possesslng this property to "bre~k" the microemulsion when ~he microemuls~on temper~ture rises to its eloud polnt tempersture range ln the hot portlons of ~n oper~ting engine cool~nt system, thereby ~llowing the oil to co~t the met~l surfaces with which ~t comes in cont~ct. In cooler portions of the engine coolRnt system, ~or ex~mple, in the overflow tAnk, below ~he cloud point temper~ture r~nge of the emulsifier selected, the compositlon ls in microemulsion or st~ble dispersed mscrOemulslon form. Re-microemulsif~cation of the sntifreeze composltlon components in ~he v~rious portlons of the enBine cool~nt system tskes place when the engine ls not oper~tlng, and thus ~llowed to cool down so that the ~nti~reeze temper~ture drops below its cloud po~n~.
The preferred emuls~f~ers for use in the present invention ~re the nonionic surfactsnts.
These are preferred bec~use they ~re generally low foaming ~nd gener~lly provide f~vor~ble cloud po~nt temper~tures for the ~ntifreeze.
In gen~r~1, the tot~l emulsifler concentr~tion present ln the mlcroemulsion sh~uld be ~etween ~bout 0.1 tlmes ~nd ~bout 100 times (preferably between ~bout 0.5 times ~nd ~bout 50 tlmes, more prefer~bly between ~bout 2 ~nd about 10 3~2~
times) the concentr~tion of oil present in the m~croemulsion, with the proviso that the totsl amount of oil plus emulsifier ~nd alc~hol cannot exceed 100 wt percent of the microemulsion. lf the surf~ct~nt concentr~tlon is below ~bout 0.1 times the oil concentr~tion, the mlcroemulsion is likely to be unstable. If the surf~ctent eoncentr~tian ls ~bo~e ~bout 100 times the oil concentration, it is likely that resultlng composition will not be economically feasible from ~ commerci~l standpoint.
The ~lcohols useful ~s the continuous (or outer) phese in the present lnvention include methanol, ~thanol, propanol, bu~anol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, butylene glycol, the monoacetate of propylene glycol, the monoethylether of glycerol, the dimethyl ether of glycerol, alkoxy alkanols (such ~s methoxyeth~nol), ~nd the like, and mixtures thereof. The preferred ~l~ohol is selected from the group consistln~ of e~hylene glycol, diethylene glycolt propylene glycol, dlpropylene glycol ~nd mixtures thereo~
The entifree2e c~ncentrate of the invention preferably has ~ pH of between about 5.5 and sbout 11 in order to provide a working ~ntifreeze pH of between about 8 ~nd ~bou~ uffers can be included in the concentrete to provide th~s pH
renge. Suit~ble buffers include, but ~re not limited to, borat~s, phosph~tes, sebac~tes and benzoates, hydroxy benzoates, or mixtures thereof.
If used, the buffer is preferAbly employed in an ~mount of between 0.1 and about 5 wt. percent ~esed ~26~6~1L31 upon the weight of the concentrate. Below about O.l wt.
percent, the buffer would not be expected to be effective, whereas above about 5 wt. percent, the amount of buffer is expected to be too costly for a commercial antifree~e.
Other optional additives may be employed in minor amounts of less than 50 wt. percent based on the weight of the concentrate. Typical optional additives would inclucle, for example, known corrosion inhibitors for aluminum or other metals in admixturP with the oils and the hydrophobizing agents of the present invention such as, ~or xample, molybdates, silicates, silicones (such as those disclosed in U.S. Patent ~,3~7,496) alkali metal nitrates, alkali metal nitrites, diisopropylamine nitrite, dicyclohexylamine nitrate, tolyltriazole, mercaptobenzothiazole, benzotriazole, and the like, or mixtures thereof. If one or more of the known inhibitors are employed together with the inhibitors of the present invention, the sum total of all inhibitors should be used in an "inhibitory effective amount", i.e., an amount sufficient to provide a measurable amount of corrosion inhibition with xespect to the metal (e.g. copper, steel, brass, aluminum, cast iron, salder, etc.) surfaces to be protected as compared to the antifreeze without these inhibitors. The corrosion inhibitors, if used, can be not only conventional alcohol-soluble inhibitors, but also oil-soluble corrosion inhibitors can be used in the microemulsions of the present invention. These oil-soluble corrosion ~/ ~ 's ~ 18 ~

inhlbi~ors ~re preferred in the pr~ctlce of thls inven~lon. ~ther typlc~l optional ~ddltives would include wetting ~gents ~nd suTf~ct~nts such ~s~ for example, known ionic ~nd non-ionlc surf~ctsnts such ~s the poly(oxyalkylene) sdducts o~ fatty alcohols;
~ntifo~ms ~nd/or lubrlc~nts such ~s the well-kno~n polysilox~nes ~nd the polyoxy~lkylene glycols, oil-soluble lnhibitors, such ~s zinc dithiophosph~tes and zinc dithioc~rb~m~tes, lubricants such as sllicone pump lubric~nts, RS well as any other minor ingred1ents known in the art that do not ~dversely ~ffect the ~ntifr2eze ch~r~cter~stics sought to be ~chieved.
One minor ~dditive th~t is particul~rly pre~erred is ~ defoamer in view of the subst~ntisl qu~nti~ies of emulsifier employed in the present invention. A p~rticul~rly pre~erred de~oamer is commerci~lly sv~ ble under the ~redem~rk "SA~"
silicone defoamer product of Union Csrbide and is prefer~bly employed in ~mounts of less th~n 0.5 wto ~ercent b~sed upon the weight of the microemulsion in the ~nti~reeze.
The microemulsions of the present invention can be prep~red by ~ny known method such AS, for example, by mixing the ~ndlvidu~l components together for e short pertod of ttme. Another procedure for prep~rlng microemulsions is to he~t mixtu~e of the lndivldual lngredient~, while stirrlng D ~nd then ~llow the resulting microemulsion to cool ~o room temper~ture. The sequence of ~ddl~ion of the oil, slcohol, ~nd surfactant to the microemulsion mixture 18 not crltical ~nd ~he order ~ost convenient m~y be ~elected.

~l2~i~6~L

Procedures for preparing microemulsions are well known in the art and are more fully described, for example, in "Microemulsion Theory and Practice", Leon M. Prince, Editor (Academic Press, Inc. 1977).
The following example is intended to illustrate, but in no way limit, the scope of the present invention:

A. Preparation of microemulsion-containing antifreeze concentrate and working antifreeze solutions.
An oil-in alcohol microemulsion was prepared by mixing a formulation consisting of 0.2 wt. % paraffin oil, C.2 wt. %
TERGITOL~ NP-4 (a nonylphenol ethoxylate surfactant of Union Carbide Corporation having 4 average ethoxy units per molecule), and 1.67 wt. ~ TERGITOL~ 25-L-7 (a surfactant product of Union Carbide comprising ethoxylates of linear alcohols having an average number of carbons between 12 and 15 and having an average of 7 ethoxy groups per molecule) and 0.5 wt. % of GAFACm RB-400, an ethoxylated alkyl phosphate of GAF
CorporatLon, together in a borate-contalning e$hylene glycol base fluid (hereinafter Base Fluid A). The resulting composition was clear and bright in appearance.
Base Fluid A (hereinafter "Test Solution #2") had the following composition:

- 20 -~ 2G~6~

BASE FLUID A
COMPONE~T WT. ~
ethylene glycol 98.26 sodium tetr~bor~te 1.47 pent~hydr~te sodium hydroxlde (50~ aq.) _ 0.27 Total wt ~ 100.0 The ~bove microemulslon concentr~t~ w~s diluted to make ~ working ~ntlfreeze solution by mixing 33 wt. ~ of concentrste with 67 wt. ~ of "corrosive w~ter" (deionized w~ter containing 100 ppm. e~ch of S04, HC03 and Cl , all ~dded as the N~ sslts)~ The ~ntifreeze solu~ion w~s clear ~nd bright in appearance.
B. Laboratory Disc Heat Flux Test:
Method, App~r~tus ~nd Resul~s A st~nd~rd test method used in the antifree2e industry w~s employed to determine the inhibitory effect of the formulsted composition of the present invention with respect t~o he~t re~cting aluminum surfaces. This test method is described ln Corroslon~ 15,257t at 258t (1959) "L~bora~ory Me~hods for Determining Corrosion Rstes Under Heat Flux Conditi:ons", ~nd ~lso in an ASTM public~tion entitled, "Engine COO1Rn~ Testing: St~te of the Art," ~ symposlum sponsored by ASTM Committee D-15, ~t pages 17-19 (Printed, M~y 1980), both lncorpor~ted herein by reference. A summ~ry of the test equ~pmen~ and procedure follows:
The ~pp~r~tus consists of ~ ter flssk, fitted with ~ condenser, ~ thermometer, ~ cold fin~er, 8 ~emper~ture controller, ~ 1 1/2 inch - 21 - ~26 6~

di~meter x 1/4 inch thlck No. 319 sluminum o~sting ~lloy (herein "the ~lumlnum disc"), ~nd ~ soldering iron heat source.
The ~pp~r~tus W8S ~h~rged w~th 90~ ml. of the working ~ntl~reeze solution ~nd he,~ted to effect bolling ~t the ~luminum d1sc ~urf~ce ~nd to m~lnt~in a solution temper~ture of ~bout 80C. The test dur~tion was 168 hours. The weight loss of aluminum from the ~lumlnum disc w~s determined ~nd used ~s me~sure of corrosion inhlbitor effectiveness expressed ~s % inhibitlon.
~ The results ~re given in T~ble I which follows:
TABLE I
Test Solution # ~ Inhibition . ~t. Loss 1 95~ 3 mg.
2 ~control) Q~ 60 mg.

The results presented ln T~ble I above show ~ery good corrosion lnhibition sssoclated with Test : Solution #1 of the present invention, 8s comp~red to control Tes~ Solution #2 (BASE FLUID only) (95 versus 0% inhibition, respectively~.
Ex~mPle 2 The ~bove dlsk test w~s repe~ted on ~
formul~t~on of thls invention consisting of 0.5 wt.
of ~ single surf~ct~nt without ~ cloud point, n~mely GAFAC RB-400 ~nd 0.1~ tr~nsformer oil (i.e., refined miner~l oil having ~ viscosity of 57 S.S.U.
~t 100~, ~dded ~s tr~nsformer oil #600, ~ produc~
of Sexaco Corp.) in the ~boYe- described BASE FLUID
A, dlluted with corrosive w~ter ~s descrlbed in - ~2 - ~ 2 Ex~mple 1 ~bove. This formul~tion provided 95~
inhib~tion on the disk test - 3n excellent result.
In contr~st, analogous compositions withou~
tr~nsformer oil or without tr~nsformer oil ~nd RB-400 (control~ proYlded 0~ inhibltion.
Ex~mple 3 Sever~l s~mples o~ ~n oll-ln-~llcohol working ~nt~freeze solution were prep~red using the following f~rmul~tion and were then tested on the ASTM Gl~ssware ~est procedure (ASTM-D-1384). The formul~tlon consisted o~: 0.067 wt. S p~raf~in oil, 0.067 wt. ~ "TERGITOL NP4", 0.1 ~t. ~ "TERGITOL
25-L-7", 0.04 wt. % "GAFAC RB400", 31.95 wt. ~
ethylene glycol, 1.26 wt. ~ sodium met~bor~te octa hydrate, 0.12 wt. ~ sodium mercsptobenzothiazole snd 66.4 wt. % corrosive w~ter cont~lning 100 ppm 504,HC03,Cl in Na s~lt. Thls formulation appeared opalescent. The Gl~ssw~re test is a beaker test procedure whereby metal specimens are immersed in 180F he~ted antifreeze ~or 336 hours and metal we~ght lost due ~o corrosion durlng immersion is measured. As ~ control, bor~te-cont~ining ethylene glycol base fluid without oll ~nd ~urfactant was employed.
The results ~re given in T~ble II whlch follows:

- ~3 -TAB~E II - ASTM-D-138~4 (mg~. Wt, 10~8 per 1 inch x 2 inch ~pecimen~
Addltlonsl , Speclmen C~t ASTM ' High-Lesd Al Fe Steel Br Solder Cu , Solder ~lcro-emul~on lg 1 ~ ~ 7 6 6 ~ 16 oontrol 63 1 3 7 5 8 j ~2 The above result~ fo~ the glassware ~ests ~how thQt the ~icroemul~ion oompositlon provides Improved ~luminum, ~nd hlgh-lead ~older cor~osion ~nhibitlon, ~ compared to the control botate buffer compo~itisn. Result~ for ASTM ~older, copper, brass snd ~teel ~re considered to be comparable.
Ex~mPle 4 Additionsl mlcroemulsion-con~aining ~ntlfreezes were made u~ing Bs~e Fluid A, identlfled ~bove, to which w~s added the v~rious o~ls ~nd hydrophobizer~ ldentif~ed ln Ta~le III which follows. Ex~minstlon of e~ch o~ ehe mixtures described in T~ble III ~howed them to have the charflcterl~ic~ of ~ microemul~lon. Th~t is, they were each clear and st~ble compositions. Thi~
demonstr~tes thst microemul~ion-cont~lning ~ntifreeze compo~itlon~ can be made u~lng vsrlou oils (corn oil, miner~l oil, paraff~n o~l, trsnsformer oil), optlonslly in the presence of vsrious hydrophoblzers.

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t~ # ~ ~, - 25 - ~ 2 Ex~mple 5 In order to demonstr~te the effectlvenes~
of the mlcr~emulsion-containing ~ntifreeze of the present ~nventlon, ~ 1982 Chevrole~ Cit~tion ~utomobile, equlpped with 8 Y-6 engine ~nd h~ving 10.6 liter nom~nal cooling system ~nd a thermost~t set ~t lg5F, w~s tested as follows.
The car coolant system w~s fl.Lled with a 50:50 volume mixture of sntlfreeze Concentr~te Y ~ncl t~p water, where Qntifreeze Concentr~te Y is def~ned in T~ble IV below~
- TABLE IV - ANTIFREEZE CONCENTRATE Y

Ethylene Glycol 92.2693 Tr~nsformer Oil 0.9975 TERGITOL NP-4* 0.9975 TERGITOL 25-L-12~ 3.7406 Water, dlstllled 1.9950 10~ . 0000 * defined in Ex~mple 1~ ~bove.
The car cont~ining the above aqueous ~ntifreeze was tested over ~n 11 dAy period by cycling (i.e., starting the engine, running 1~ for several minutes, ~hen cooling 1~) the englne 39 times ~nd driving the c~r over 303 miles. The original 50 percent aqueous Antifreeze h~d an oil-cont~ining ph~se of 12.7 volume percent. After 24 engine on-off cycles the oil-cont~ining ph~se in the overflow tan~ of the cool~nt system w~s 12.5 volume percent. After 32 cycles, the overflow t~nk had ~n oil ph~se content Q~ 10.8 volume percent, es comp~red to an oil ph~se content of 10.5 volume percent in the bulk engine fluid. Af~er 39 cycles, ~-1426~

- 26 - ~ 6~

the overflow tank h~d ~n oil-contAining phase of 10.8 volume percent, where~s the oil phsse content of the bulk englne fluid w~s 10.6 volume percen~.
The ~bove test results lndic~te clearly th~t sn oil content ~quilibrium between the bulk engine fluid ~nd the overflow tank w~s re~ched after ~ number of on-off cycles of the en8ine ~nd that microemulsion-~ntifreeze h~ving ~ cloud point of 77C did not ~ggregate the oil ph~se in either the m~in coolant system or in the overflow tank.
Re-microemulsif~cstion of the antifreeze tooX place in the coollng system ~fter the ~ntlfreeze returned to below its cloud point.
A simil~r car test was conducted using an ~ntifreeze composi~ion h~ving ~ cloud point of ~bout 60C. Complete re-microemulsific~tion of this antifreeze in the cool~nt system did not t~ke pl~ce when the system was cooled down. Also, the oil distribution ln the ~ntifreeze w~s not uniform in the v~rious parts of the system on cool down.
Example 6 The disk test described in Ex~mple 1 w~s repeated on a formulRtion of this invent~on eonsisting of 0 r 59 wt . ~ of ~ solutlon o$ 10 wt . 70 of ~n oil-soluble corrosion inhibitor, n~mely AMINE
O, an oleyl~modazoline product of Ciba-Gelgy, in p~r~ffln oil, 0.59 wt. ~L TERGITOL NP-4, 0.89 wt.
TERGITOL 25-L-7, 0.35 wt. 7~ GAFAC RB-400 snd 97.5 wt. ~ BASE FLUID A, described ~bove, diluted wlth "corrosive" water ~s described ~n Ex~mple 1 ~bove.
This formul~tion provided 100~ lnhibition on the disk test - ~n excellent result. In contrA~, a control ex~mple using BASE FLUID A provldes O
inhibitlon.
While ~his invention h~s been descrlbed with reference to cert~in specific embodiments, lt will be recognlzed by those skilled in thls ~rt that many vari~tions are possible without dep~rting from the srope ~nd spirit of the invention ~Ind that lt is lntended to cover all changes ~nd modific~tions of the invention disclosed herein for the purposes of illustratlon which do not constitute departure from the spirlt and scope of the lnvention.

Claims (19)

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

1. An oil-in-alcohol microemulsion-containing antifreeze composition concentrate having a discontinuous phase and a continuous phase comprising:
(a) at least one alcohol in an amount sufficient to form a continuous phase in the concentrate;
(b) alcohol insoluble oil particles forming a discontinuous phase in said composition, said particles having a particle size less than about 0.1 micron:
(c) at least one hydrophobizing compound selected from the group consisting of organic derivatives of the following:
phosphate, sulfate, phosphonate, sulfonate, ammonium and phosphonium salts, amine oxides, phosphine oxides, amphoteric and zwitterionic groups, and mixtures thereof wherein the organic group is selected from the class consisting of the following radicals: alkyl, alkenyl, alkynyl, aryl, all having up to about 24 carbon atoms, alkyleneoxy, polyalkyleneoxy, and combinations thereof; and (d) at least one emulsifier present in an amount sufficient to stabilize the microemulsion.

2. The concentrate of claim 1 wherein said emulsifier provides a cloud point for the antifreeze between 40°C and 125°C.

3. The concentrate of claim 2 wherein said emulsifier provides a cloud point for the antifreeze between 65°C and 125°C.

4. The concentrate of claim 1 wherein said alcohol is selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and mixtures thereof.

5. The concentrate of claim 2 wherein said oil particles are present in an amount of between about 0.001 and about 5 wt.
percent based on the total weight of the microemulsion, and wherein said emulsifier is present in an amount of between about 0.1 times and about 100 times the total weight of said oil particles in the microemulsion, and wherein said alcohol is present in an amount of at least about 50 wt. percent based on the weight of the concentrate, and wherein the hydrophobizer is present in an amount of between about 0.001 and about 30 wt.
percent based on the weight of the microemulsion, with the proviso that the total weight of the concentrate not exceed 100 wt. percent.

6. The concentrate of claim 2 wherein said emulsifier consists essentially of non-ionic, anionic or cationic surfactants, or mixtures thereof.

7. The concentrate of claim 2 wherein said emulsifier consists of a mixture of at least two non-ionic surfactants.

8. The concentrate of claim 1 wherein said insoluble particles have an average particle size of less than about 0.05 microns.

9. The concentrate of claim 1 wherein component (c) is a propylene oxide or ethylene oxide/propylene oxide-containing organophosphate ester.

10. The concentrate of claim 9 wherein said organophosphate ester has an average molecular weight below about 10,000.

11. The concentrate of claim 1 wherein said organophosphate ester has the structural formula:

wherein each substituent R1, R2, and R3 is selected from the class consisting of the following radicals: hydrogen; alkyl, aryl, alkenyl and alkynyl, with each of the foregoing having up to about 24 carbon atoms, alkyleneoxy, polyalkyleneoxy;
phosphate or polyphosphate or their salts; and combinations thereof; with the proviso that at least one of said substituents is an organic radical within the class listed above or combinations thereof.

12. The concentrate of claim 1 having a pH
of between about 5.5 and about 11.

13. The concentrate of claim 1 which additionally contains silicate in a corrosion-inhibiting effective amount.

14. The concentrate of claim 1 which additionally contains an antifoam additive in an amount effective to minimize foaming of said concentrate.

15. The concentrate of claim 2 wherein said oil particles are present in an amount of between about 0.1 and about 3 wt.
percent based on the total weight of the microemulsion, and wherein said emulsifier is present in an amount of between about 0.5 times and about 50 times the total weight of said oil particles in the microemulsion, and wherein said alcohol is present in an amount of at least about 90 wt. percent based on the weight of the concentrate, and wherein the hydrophobizer is present in an amount of between about 0.005 and about 1 weight percent based on the weight of the microemulsion, with the proviso that the total weight of the concentrate not exceed 100 wt. percent.

16. An antifreeze composition comprising the concentrate of any of claims 1, 2 or 5 which comprises diluting the concentrate with water or a mixture of water and alcohol to make a working antifreeze.

17. An antifreeze composition comprising the concentrate of any of claims 1, 2 or 5 and additionally containing water and/or alcohol in an amount sufficient to provide a diluted antifreeze having a pH of between about 8 and about 11.

18. The concentrate of any of claims 1, 2 or 5 which additionally contains an oil soluble corrosion inhibitor in said discontinuous phase.

19. An oil-in-alcohol microemulsion containing antifreeze composition concentrate having a discontinuous phase and a continuous phase comprising:
(a) at least one alcohol in an amount sufficient to form a continuous phase in the concentrate;
(b) alcohol insoluble oil particles forming a discontinuous phase in said composition, said particles having a particle size less than about 0.1 micron;
(c) at lease one hydrophobizing compound selected from the group consisting of organic derivatives of the following:
phosphate, sulfate, phosphonate, sulfonate, carboxylate, ammonium and phosphonium salts, amine oxides, phosphine oxides, amphoteric and zwitterionic groups, and mixtures thereof wherein the organic group is selected from the class consisting of the following radicals: alkyl, alkenyl, alkynyl, aryl, all having up to about 24 carbon atoms, alkyleneoxy, polyalkyleneoxy, and combinations thereof; and (d) at least one emulsifier present in an amount from zero up to an amount sufficient to stabilize the microemulsion in the composition said emulsifier providing a cloud point for the antifreeze of from about 40°C to about 125°C.