Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
- 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
D-14268-1-C
- 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
D-14268-1
- 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.
D-14268-1
- 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
D-14268-1
- 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$1, paraffln oil, veget~ble oil,
n~phtha oll, petroleum b~se oll, mixed xylenes,
kerosene, miner~1 spirlt, transformer oil, fuel oil,
silicone oil, sll~ne esters, synthetic oil,
h~logen~ted ~ils, polypropylene glycols, propylene
ox~de/ethylene ox~de copolymers, propylene
oxide/butyl~ne oxide copolymers, ethylene
oxide/butylene oxide copolymers, ethylene
oxide/propylene oxidelbutylene oxide terpolymers, ~s
well ~s sulf~ted, sulfonAted, ~hosphated snd
phosphonsted oils, h~gher ~lcohols ~nd esters
thereof, And the like.
The ~mount of oil present in the
microemulsions of ~he present lnvent~on c~n v~ry
over ~ wide r~nge, but is prefer~bly between ~bout
0.001 to Rbout 5 (more prefer~bly between sbout 0.1
~nd about 3) wt. percen~ bQsed upon ~he tot~l weight
of the microemulsion. Within the ~bove-specified
preferred r~nges, ~he ~mount of oil used ln the
mlcroemulslon is dependent upon the p~rticul~r
~ntlfreeze end use required for the microemulslon.
D-14268-1
- 9
Below ~bout 0.001 wt perc2nt, ~he smoun~ of oil
would gener~lly be insufflcient to be functlon~l,
where~s above ~bout ~ weight percent ~he ~nt~freeze
m~y not s~isfy governmen~l freezing polnk
depresslon specificAtions for ~ntifreeze.
As used herein, the term "hydrophobizing .
~gent'l denotes R compound that is adsorbed by the
metal surf~ces of fl cooling system and lmp~rts ~n
~fflnity between the metal surf~ces ~nd oil in the
microemulsion. Useful hydrophobizing agents ~re
selected ~rom the group consisting of orgflnic
derivatlves o$ 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
O-R2
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
D-14268-1
~Z~
- 10 -
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.
D-14268-1-C
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.
D-14268-1
- 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
D-14268-1
- 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
D-14268-1
~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
D-14268-1
- 16 -
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
D-14268-1
~26~6~1L31
- 17 -
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
D-14268-1-C
~/ ~ '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.
D-14268-1
~l2~i~6~L
- 19 -
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:
EXAMPLF 1
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:
D-14268-1-C
- 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
D-14268-1
- 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
D-14268-1
- ~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:
D-14268-1
- ~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.
D-14268-1
- 24- ~6~6~
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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
D-14268-1
- 27
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.
D-14268-1
