U.S. patent application number 11/250692 was filed with the patent office on 2006-02-16 for engine antifreeze composition.
This patent application is currently assigned to Fleetguard, Inc.. Invention is credited to R. Douglas Hudgens.
Application Number | 20060033077 11/250692 |
Document ID | / |
Family ID | 24448919 |
Filed Date | 2006-02-16 |
United States Patent
Application |
20060033077 |
Kind Code |
A1 |
Hudgens; R. Douglas |
February 16, 2006 |
Engine antifreeze composition
Abstract
In general this invention relates to an antifreeze composition
that can be used in the cooling systems of internal combustion
engines, for example, in heavy-duty diesel engines, light duty
trucks and cars. The antifreeze composition can be added to water
or other suitable liquid coolant in the cooling system, to lower
the freezing point temperature of the coolant and inhibit corrosion
of metallic components associated with the cooling system. The
antifreeze composition is particularly well suited, although not
exclusively, for use with hard water. The antifreeze composition
includes an organic acid component comprising adipic acid and at
least one of benzoic acid and one or more C.sub.9-C.sub.12
dicarboxylic acid--or salts of these acids. The antifreeze
composition also includes other anti-corrosive additive, for
example, molybdate, nitrite, nitrate silicate azoles and a variety
of buffer agents.
Inventors: |
Hudgens; R. Douglas;
(Cookeville, TN) |
Correspondence
Address: |
WOODARD, EMHARDT, MORIARTY, MCNETT & HENRY LLP
111 MONUMENT CIRCLE, SUITE 3700
INDIANAPOLIS
IN
46204-5137
US
|
Assignee: |
Fleetguard, Inc.
|
Family ID: |
24448919 |
Appl. No.: |
11/250692 |
Filed: |
October 11, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09611413 |
Jul 6, 2000 |
6953534 |
|
|
11250692 |
Oct 11, 2005 |
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Current U.S.
Class: |
252/75 |
Current CPC
Class: |
C09K 5/20 20130101; C23F
11/08 20130101 |
Class at
Publication: |
252/075 |
International
Class: |
C09K 5/00 20060101
C09K005/00 |
Claims
1. An engine coolant composition comprising: an organic acid
component or salt thereof, said organic acid component comprising
adipic acid and at least one of benzoic acid and a C.sub.9-C.sub.12
aliphatic dicarboxylic acid; an anticorrosion additive including
molybdate, and at least one of mercaptobenzothiazole,
benzotriazole, tolyltriazole, nitrite, nitrate, and silicate; a
buffer component comprising a sodium salt of at least one of a
borate salt or a phosphate salt and a freezing point
depressant.
2. The coolant composition of claim 1 wherein the adipic acid or a
salt thereof is included in an amount between about 0.1 wt % and
about 5 wt %, measured as the free acid and based on the total
weight of the coolant composition.
3. The coolant composition of claim 1 comprising between about 0.5
wt % and about 10 wt % of the organic acid component, measured as
the free acid and based upon the total weight of the coolant
composition.
4. The coolant composition of claim 1 wherein the benzoic acid or
C.sub.9-C.sub.12 aliphatic dicarboxylic acid is included in an
amount between about 0.5 wt % and about 5 wt %, measured as the
free acid and based on the total weight of the coolant
composition.
5. The coolant composition of claim I provided to have a pH level
between about 7.5 and about 11 pH units.
6. The coolant composition of claim 1 provided as a liquid
concentrate.
7. The coolant composition of claim I provided as a
ready-to-use-formulation for a internal combustion engine cooling
system.
8. The composition of claim 1 comprising: an organic acid component
or salt thereof including adipic acid, benzoic acid and at least
one C.sub.9-C.sub.12 aliphatic dicarboxylic acid; an anticorrosion
additive including molybdate, nitrite, nitrate, silicate and at
least one of mercaptobenzothiazole, benzotriazole, or
tolyltriazole; a borate salt; and a freezing point depressant.
9. The composition of claim 1 comprising: an organic acid component
or salt thereof, said organic acid component consisting of adipic
acid, benzoic acid and at least one C.sub.9-C.sub.12 aliphatic
dicarboxylic acid; an anticorrosion additive including molybdate,
nitrite, nitrate, and at least one of mercaptobenzothiazole,
benzotriazole, or tolyltriazole; a phosphate salt; and a freezing
point depressant.
10. The composition of claim 1 comprising: between about 0.1 wt %
and about 0.5 wt % adipic acid, between about 1.0 wt % and about
2.0 wt % of an aliphatic dicarboxylic acid or a salt thereof, said
dicarboxylic acid selected from the group consisting of: sebacic
acid, dodecanedioic acid and mixtures thereof, between about 0 wt %
and about 0.5 wt % nitrite salts, between about 0 wt % and about
0.5 wt % nitrate salts, between about 0 wt % and about 0.5 wt %
molybdate salts, between about 0 wt % and about 0.5 wt % silicate
salts, between about 0.1 wt % and about 0.5 wt % of at least one of
mercaptobenzothiazole, benzotriazole, or tolyltriazole, and between
0.1 wt % and about 0.5 wt % of at least one of borate salts and
phosphate salts; and between about 80 wt % to about 99 wt % of at
least one of ethylene glycol or propylene glycol.
11. A coolant composition comprising, in weight percent: between
about 0.1 wt % and about 0.5 wt % adipic acid, between about 1.0 wt
% and about 2.0 wt % sebacic acid, between about 0.1 wt % and about
0.5 wt % of at least one of mercaptobenzothiazole, benzotriazole,
or tolyltriazole, between about 80 wt % to about 99 wt % of at
least one of ethylene glycol or propylene glycol, and optionally
between about 0.1 wt % and about 0.5 wt % molybdate salts.
12. The composition of claim 11 consisting essentially of, in
weight percent: between about 0.1 wt % and about 0.5 wt % adipic
acid, between about 2.0 wt % and about 3.0 wt % of an aliphatic
dicarboxylic acid pr a salt thereof, said dicarboxylic acid
selected from the group consisting of: sebacic acid dodecanedioic
acid, and a mixture thereof, between about 0.5 wt % and about 2.5
wt % benzoic acid, between about 0.1 wt % and about 0.5 wt %
nitrite salts, between about 0.1 wt % and about 0.5 wt % nitrate
salts, between about 0.1 wt % and about 0.5 wt % molybdate salts,
between about 0.1 wt % and about 0.5 wt % of at least one of
mercaptobenzothiazole, benzotriazole, or tolyltriazole, and between
about 80 wt % to about 99 wt % of at least one of ethylene glycol
or propylene glycol.
13. An engine coolant composition comprising: an organic acid
component, said organic acid component comprising adipic acid and
at least one of benzoic acid and a C.sub.9-C.sub.12 aliphatic
dicarboxylic acid or salts of these acids; an anticorrosion
additive including molybdate, and at least one of
mercaptobenzothiazole, benzotriazole, tolyltriazole, nitrite,
nitrate, and silicate; a buffer component comprising at least one
of a borate salt or a phosphate salt; and hard water.
14. The coolant composition of claim 13 comprising a freezing point
depressant.
15. The coolant composition of claim 13 wherein the adipic acid or
a salt thereof is included in an amount between about 0.1 wt % and
about 5 wt %, measured as the free acid and based on the total
weight of the coolant composition.
16. The coolant composition of claim 13 comprising between about
0.5 wt % and about 10 wt % of the organic acid component, measured
as the free acid and based upon the total weight of the coolant
composition.
17. The coolant composition of claim 13 wherein the benzoic acid or
C.sub.9-C.sub.12 aliphatic dicarboxylic acid or a salt thereof is
included in an amount between about 0.5 wt % and about 5 wt %,
measured as the free acid and based on the total weight of the
coolant composition.
18. The coolant composition of claim 13 provided to have a pH level
between about 7.5 and about 11 pH units.
19. A method of reducing the corrosion of metal surfaces in a
cooling system having a recirculating liquid coolant comprising
hard water, said method comprising: adding to said liquid coolant,
an additive comprising an organic acid component or salt thereof,
said acid component comprising a mixture of a C.sub.4-C.sub.6
dicarboxylic acid and at least one of benzoic acid or a
C.sub.9-C.sub.12 aliphatic dicarboxylic acid; and an anti-corrosion
additive including molybdate, and at least compound selected from
the group consisting of: mercaptobenzothiazole, benzotriazole,
tolyltriazole, nitrite, nitrate, and silicate.
20. The method of claim 19 wherein the liquid coolant is maintained
at a pH level between about 7.5 and about 11 pH units.
21. The method of claim 19 wherein the C.sub.4-C.sub.6 dicarboxylic
acid or salt thereof is added in an amount sufficient to enhance
the inhibition of corrosion of aluminum containing components
relative to a liquid coolant without the C.sub.4-C.sub.6
dicarboxylic acid or salt thereof.
22. The method of claim 19 wherein the additive comprising a buffer
agent selected from the group consisting of: borates, phosphates,
benzoates and mixtures thereof.
Description
FIELD OF THE INVENTION
[0001] In general, this invention is related to a coolant
composition. More specifically, but not exclusive, this invention
is directed to a coolant composition that includes anti-corrosion
additives for use in combustion engines and a method of inhibiting
the corrosion of components in cooling systems.
BACKGROUND OF THE INVENTION
[0002] Typically coolant compositions are specifically formulated
with ethylene glycol or propylene glycol or their derivatives and
include specific additives that inhibit and reduce corrosion of
coolant systems. Specific coolant formulations are desired because
with the advent of higher performance engines, particularly
heavy-duty diesel engines, increasing more components of these
engines are manufactured from a wide variety of materials to reduce
weight and increase efficiency. Similarly, the coolant coursing
through these engines contact a variety of materials. Typically
additives are selected to impart particular benefits, such as
providing protection for one or more selected materials. In
addition, it is not uncommon for the additives to be selected to
compliment each other's beneficial properties. Despite the
specificity which these coolant compositions are formulated, the
benefits associated with many of the additives can be thwarted
because a large percentage of operators include hard water in the
cooling system. The hard water can be added either upon initially
filling the cooling system or during in-service as operators add
make-up water to top off the cooling system.
[0003] In many parts of the world, there is no ready access to
suitable water for use in cooling system. Hard water includes a
number of minerals, most notably calcium, magnesium and iron salts.
These minerals may contribute to loss of efficacy and reduce the
usable lifetime of the coolant composition. This loss can be
particularly detrimental to heavy duty diesel trucks that can cover
over 10,000 miles a month. An ineffective coolant composition can
shorten engine life, allow internal passageways in the cooling
system to clog, contribute to cylinder liner pitting and water pump
cavitation all which result in costly engine overhauls.
[0004] Thus in light of the above described problems, there is a
continuing need for advancements in the coolant compositions and
improved methods for reducing corrosion associated with cooling
compositions. The present invention is such an advancement and
provides a wide variety of benefits and advantages.
SUMMARY OF THE INVENTION
[0005] The present invention relates to novel coolant compositions,
the manufacture and use thereof. Various aspects of the invention
are novel, nonobvious, and provide various advantages. While the
actual nature of the invention covered herein can only be
determined with reference to the claims appended hereto, certain
forms and features, which are characteristic of the preferred
embodiments disclosed herein, are described briefly as follows.
[0006] In one form the present invention provides an engine coolant
composition that can be used in a cooling system. The engine
coolant composition comprises: an organic acid component or salt
thereof. The organic acid component can include a C.sub.4-C.sub.6
dicarboxylic acid and at least one of benzoic acid and a
C.sub.9-C.sub.12 aliphatic dicarboxylic acid. The engine coolant
also comprises an anticorrosion additive including molybdate, and
at least one of mercaptobenzothiazole, benzotriazole,
tolyltriazole, nitrite, nitrate, and silicate; a buffer component
comprising a sodium salt of at least one of a borate salt, and/or a
phosphate salt and a freezing point depressant. In one embodiment
the organic acid component of the coolant composition includes
adipic acid, benzoic acid and optionally a C.sub.9-C.sub.12
aliphatic dicarboxylic acid. In other embodiments the coolant
composition includes molybdate, nitrite, nitrate and at least one
of mercaptobenzothiazole or tolytriazole and a buffering agent.
[0007] In another form the invention provides an engine coolant
composition comprising an organic acid component or salt thereof.
The organic acid component can include adipic acid and at least one
of benzoic acid and a C.sub.9-C.sub.12 aliphatic dicarboxylic acid
or salts of these acids; an anticorrosion additive including
molybdate, and at least one of mercaptobenzothiazole,
benzotriazole, tolyltriazole, nitrite, nitrate, and silicate; a
buffer component comprising at least one of a borate salt or a
phosphate salt and hard water.
[0008] In still yet another form the present invention provides a
method of reducing the corrosion of metal surfaces in a cooling
system having a recirculating liquid coolant comprising hard water.
The method comprises adding an additive to the liquid coolant. The
additive can include an organic acid component or salt thereof, a
anti-corrosion additive and a buffer agent. The acid component can
comprise a mixture of a C.sub.4-C.sub.6 dicarboxylic acid and at
least one of benzoic acid or a C.sub.9-C.sub.12 aliphatic
dicarboxylic acid. The anti-corrosion additive can include
molybdate, and at least one compound selected from the group
consisting of: mercaptobenzothiazole, benzotriazole, tolyltriazole,
nitrite, nitrate, and silicate.
[0009] Further objects, features, aspects, forms, advantages and
benefits shall become apparent from the description and drawings
contained herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a scanned image of two aluminum coupons after
evaluation in different engine antifreeze compositions according to
the Erosion Corrosion Bench Test.
[0011] FIG. 2 is a scanned image of an alternate view of the
coupons depicted in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0012] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated herein and specific language will be used
to describe the same. It will nevertheless be understood that no
limitation of the scope of the invention is thereby intended. Any
alterations and further modifications in the described processes,
systems or devices, and any further applications of the principles
of the invention as described herein, are contemplated as would
normally occur to one skilled in the art to which the invention
relates.
[0013] In general, this invention is directed to an engine coolant
composition for heavy duty diesel engines, light duty trucks and
automobiles. This invention can also provide various other
advantageous applications, for example, in any heat-transfer
application, preferably using an aqueous-based or alcohol-based
(including glycols) or otherwise compatible heat-transfer medium.
The coolant composition provides excellent antifreeze capabilities
and therefore lowers the temperature at which the engine coolant
begins to solidify or freeze. In preferred embodiments, this
invention includes an organic acid component of a C.sub.4-C.sub.6
dicarboxylic acid and at least one other organic acid in
combination with other anti-corrosion additives and buffering
agents to reduce corrosion of metal components and clogging of
internal system passageways. It has been determined that certain
preferred embodiments unexpectedly exhibit enhanced anti-corrosion
properties in the presence of hard water.
[0014] The term "hard water" when used in this present application
is understood as water that includes a variety of minerals or
inorganic salts, particularly cationic alkali metal salts, for
example, calcium salts, magnesium salts, iron salts. Hard water can
typically be evaluated in terms of its hardness level, which is
often reported in parts per million (ppm). Hardness can be
determined using a variety of commercially available water test
kits, for example, using a test kit sold under the trademark
Monitor C.TM. by Fleetguard, Inc. Water is considered to be hard at
a hardness level of about 170 ppm or greater and very hard at a
hardness level of about 300 ppm or greater.
[0015] In preferred formulations, the engine coolant composition of
the present invention includes a specifically tailored combination
of organic acids, anti-corrosion agents and buffering agents to
reduce the corrosion associated with hard water. This can provide
an added benefit of allowing a lower concentration of selected
agents to yield equally effective anti-corrosion protection. The
present invention provides an enhanced benefit of reducing
precipitation of salts associated with the use of hard water in
coolant systems.
[0016] The cooling composition can be provided as a liquid
concentrate or as a ready-to-use formulation, i.e., a pre-diluted
formulation. The ready-to-use formulation can be used "as is" in a
cooling system. More preferably the ready-to-use formulation is
diluted with water at a dilution ratio, by volume, of about 1 part
formulation to 0.4 parts water to about 1 part formulation to about
1.6 parts water.
[0017] The engine coolant composition of the present invention
includes an organic acid component and other anti-corrosive
additives. It should be understood that the organic acids impart
significant anti-corrosive properties, as well as other beneficial
properties. The organic acid component consists essentially of a
C.sub.4-C.sub.6 aliphatic dicarboxylic acid and at least one of an
aromatic carboxylic acid and a C.sub.9-C.sub.12 dicarboxylic acid
or salts of these acids. The anti-corrosive additives can be a
combination of inorganic and organic agents.
[0018] Specific examples the C.sub.4-C.sub.6 aliphatic dicarboxylic
acid for use in the present invention include maleic acid, succinic
acid, and adipic acid. In a more preferred form, the organic acid
component includes adipic acid. The C.sub.4-C.sub.6 aliphatic
dicarboxylic acid is included in the coolant composition in an
amount sufficient to inhibit corrosion of metal surfaces in the
cooling system. Preferably the coolant composition includes the
C.sub.4-C.sub.6 aliphatic dicarboxylic acid in an amount between
about 0.1 weight percent (wt %) and about 5 wt % measured as the
free acid and based upon the total weight of the coolant
composition. More preferably, the coolant composition includes
between about 0.1 wt % and about 1 wt % of adipic acid; still yet
more preferably, the coolant composition includes between about 0.1
wt % and about 0.5 wt % of the adipic acid. It has been
unexpectedly determined that when the coolant composition includes
the minor amount of adipic acid, the coolant composition exhibits
significantly enhanced anti-corrosive properties, particularly when
the coolant composition is combined with hard water.
[0019] The organic acid component can also include an aromatic
carboxylic acid. Preferably the aromatic carboxylic acid is
selected to include benzoic acid or a salt thereof. The coolant
composition includes the aromatic carboxylic acid in varying
amounts. When the coolant composition is provided in a ready-to-use
formulation, the coolant includes between about 0.1 wt % and about
5 wt % benzoic acid or benzoate measured as the free acid and based
upon the total weight of the coolant composition. More preferably,
the coolant composition includes between about 0.5 wt % and about
2.5 wt % benzoic acid or benzoate; still yet more preferably the
coolant composition includes between about 0.6 wt % and about 1.5
wt % benzoic acid or benzoate.
[0020] The organic acid component can also include a
C.sub.9-C.sub.12 dicarboxylic acid. Preferably the C.sub.9-C.sub.12
dicarboxylic acid is selected to include azelaic acid, sebacic
acid, undecanedioic acid and dodecanedioic acid or salts of these
acids. The coolant composition includes the C.sub.9-C.sub.12
dicarboxylic acid in varying amounts. When the coolant composition
is provided in a ready-to-use formulation, the coolant includes
between about 0.1 wt % and about 5 wt % C.sub.9-C.sub.12
dicarboxylic acid or salt thereof measured as the free acid and
based upon the total weight of the coolant composition. More
preferably, the coolant composition includes between about 0.5 wt %
and about 2.5 wt % of a C.sub.9-C.sub.12 dicarboxylic acid or salt
thereof; still yet more preferably the coolant composition includes
between about 1.0 wt % and about 2.0 wt % C.sub.9-C.sub.12
dicarboxylic acid or salt thereof. In alternative embodiments of
this invention, the coolant composition can include between about
2.0 wt % and about 3.0 wt % of the C.sub.9-C.sub.12 dicarboxylic
acid or salt thereof.
[0021] The salts of these acids are preferably, but not
exclusively, ammonium, tetraalkyl ammonium and alkali metal salts
and would include, for example, lithium, sodium and potassium
cations. Although it is understood that sodium and potassium salts
are more preferred.
[0022] The coolant composition of the present invention also
includes additional anti-corrosive additives. The anti-corrosive
additives can be either an organic additive or an inorganic
additive. Examples of organic anti-corrosive additives include
benzotriazole, tolytriazole, mercaptobenzothiazole, sulfonates and
imidazolines. Preferably the coolant composition of the present
invention includes tolytriazole and/or mercaptobenzothiazole. The
organic anti-corrosive additives can be included in varying
amounts, preferably between about 0.05 wt % and about 0.5 wt %.
More preferably, the coolant composition includes between about 0.1
wt % and about 0.5 wt % of the individual organic anti-corrosive
additives.
[0023] The coolant composition can also include inorganic
anti-corrosive additives. The inorganic additives include borates,
phosphate silicates, nitrates, nitrites and molybdates. These
inorganic anti-corrosive additives can be employed at
concentrations ranging between about 0.0 wt % and about 5.0 wt %
for the ready-to-use formulation. The inorganic anti-corrosive
additives can be provided as salts, preferably ammonium, tetraalkyl
ammonium, or alkali metal salts. In preferred forms the coolant
composition includes two or more of the inorganic anti-corrosive
additives.
[0024] In preferred forms, the coolant composition includes
molybdate and at least one anti-corrosive additive selected from
the group consisting of mercaptobenzothiazole, benzotriazole,
tolytriazole, a silicate salt, a nitrite salt and a nitrate salt.
The basic coolant composition can be tailored for selective
applications to provide enhanced aluminum protection for components
of the coolant system, for example, nitrates and silicates are
known to provide aluminum protection. Borates and nitrites can be
added for ferrous metal protection, and benzotriazole and
tolytriazole can be added for copper and brass protection.
Furthermore, for heavy-duty specifications, the coolant composition
can include varying amounts of an alkali metal nitrite to provide
enhanced protection against pitting of cylinder liners for
heavy-duty diesel engines. The coolant composition can include
between about 0.0 wt % to about 0.5 wt % of each of the desired
additives. More preferably, the coolant composition can include
between about 0.05 wt % to about 0.5 wt % of the additives; still
yet more preferably between about 0.1 wt % to about 0.5 wt % of the
additives.
[0025] The coolant composition can also include buffering agents.
The buffering agents can be selected from any known or commonly
used buffering agents. It will be appreciated by those skilled in
the art that selected buffering agents can exhibit both
anti-corrosion and buffering properties. For example benzoate,
borates and phosphates can in certain formulations provide both
buffering and anti-corrosion advantages. Preferred examples of
buffers include borate salts and phosphate salts. In one preferred
form, the buffering system includes a mixed phosphate/borate buffer
system. It will also be understood by those skilled in the art that
certain engine manufacturers, governmental organizations and/or
consumers prefer or even require selected buffering systems. While
the choice of a selected buffer system is not critical for the
practice of this invention the buffering agents(s) can be selected
to comply with desires and demands of end users. In addition a base
can be included into the coolant composition to help adjust the pH
to the desired pH level. Illustrative examples of bases for use
with this invention included commonly known and used bases, for
example, inorganic bases including KOH, NaOH, and weaker bases such
as NaHCO.sub.3. K2CO.sub.3a and Na.sub.2CO.sub.3. Therefore, the
buffering system and base can be adapted to provide a coolant
composition having a pH level between 7.5 and about 11 pH units.
More preferably, the buffering system and base is selected to
provide a coolant composition with a pH level between about 8.0 and
about 9.0 pH units.
[0026] A fully formulated coolant typically includes a variety of
other additives, including, for example, defoamers, scale
inhibitors, surfactants, detergents, and dyes. Specific examples of
defoamers include components (alone or in combination) such as
silicon defoamers, alcohols such as polyethoxylated glycol,
polypropoxylated glycol or acetylenic glycols. Examples of scale
inhibitors include components, either alone or in combination, such
as, for example, phosphate esters, phosphino carboxylate,
polyacrylates, polymethacylate, styrene-maleic anhydride,
sulfonates, maleic anhydride co-polymer, acrylate-sulfonate
co-polymer and the like. Surfactants for use in this invention
include, for example, either alone or in combination: Alkyl
sulfonates, acryl sulfonates, phosphate esters, sulfosuccinate,
acetylenic glycol, and ethoxylated alcohols. Detergents include
non-ionic and/or anionic components such as, for example, phosphate
ester surfactants, sodium alkyl sulfonates, sodium aryl sulfonates,
sodium alkyl aryl sulfonates, linear alkyl benzene sulfonates,
alkylphenols, ethoxylated alcohols, carboxylic esters, and the
like.
[0027] The coolant composition of the present invention is blended
to provide a uniform composition. The order of addition of the
individual components is not critical for the practice of the
invention. However, it is desired to the coolant composition be
thoroughly blended and that all the components be completely
dissolved to provide optimum performance. As discussed above, in
one preferred form, the coolant composition is provided as a
ready-to-use, i.e. pre-diluted, formulation. When thus provided,
the ready-to-use formulation can also include a freezing point
depressant. The freezing point depressant can be selected from a
variety of known and/or commonly used freezing point depressants.
Commonly used examples include, for example, propanol, monoethylene
glycol, diethylene glycol, propylene glycol, and the like. When
provided in the coolant composition, the freezing point depressant
is added in amounts ranging between about 30 wt % and about 70 wt %
based upon the total weight of the coolant composition. The
ready-to-use coolant composition can also include varying amounts
of water.
[0028] In another form, the coolant composition of the present
invention can be provided as a liquid concentrate. Typically, the
liquid concentrate includes an alcohol or glycol and additionally
can, but is not required, to include small amounts of water to
dissolve the additives. The liquid concentrate can be added to a
cooling system and diluted with water to provide a liquid coolant.
To provide optimum performance, the liquid concentrate should be
thoroughly blended with the water prior to use. It is preferable,
but not required, to pre-mix the concentrate with the coolant
before adding to the coolant system rather than using the radiator
as a mixing chamber.
[0029] The coolant composition that includes adipic acid provides
enhanced anti-corrosion properties over compositions lacking either
one of these acids or salts of these acids. The cooling composition
provides enhanced aluminum and ferrous metal protection against
corrosion of the coolant in the cooling system.
[0030] The cooling composition of the present invention provides
unexpected results or enhanced protection in hard water. It is not
uncommon for cooling system for diesel engines and automobile
engines to include water as part of the coolant medium.
Furthermore, during operation, the cooling systems frequently lose
fluid either due to leakage or evaporation. Often, operators add
make-up fluids such as water to the cooling system. The make-up
fluid frequently is hard water, which is found in many parts of the
world. Hard water can cause many deleterious effects on the
components of the cooling systems. These effects include increased
corrosion of metal surfaces, particularly iron and aluminum
surfaces. Furthermore, the hard water can cause incompatibility
problems with some of the anti-corrosion components. For example,
hard water containing calcium and magnesium salts can cause
additives to precipitate or gel. This can decrease engine
protection and increase corrosion. In a typical on-highway
heavy-duty diesel engine cooling system, the flow rate can range
from 80 to 150 gallons per minute. This means that flow velocities
can reach 8 to 10 feet per second. Tests have shown that solder and
aluminum are sensitive to the effects of high flow rate. These
effects are acerbated by the addition of any solid or gelled
additives.
[0031] It has unexpectedly been determined that the addition of
adipic acid significantly enhances the protection of aluminum
components in contact with hard water. For example, if additives,
such as silicates, precipitate from the coolant composition, the
desired aluminum protection previously afforded by the soluble
silicate is drastically reduced. While not to be bound by any
theory, it is thought that adipic acid and its salts provide
significant enhanced aluminum metal protection, and at least part
of this effect may be attributed to reduced precipitation of
certain additives.
[0032] While not to be considered limiting in any fashion, it is
also thought that the addition of adipic acid to the cooling
composition provides enhanced protection for metal surfaces by
chelating or combining with the alkali metal cations, specifically
calcium and magnesium. These cations contribute to the buildup of
scale on hot metal surfaces. The scale can drastically reduce and
even eliminate flow through passageways in the cooling system. The
scale can also inhibit efficient heat transfer from the hot metal
surfaces to the coolant. Chelation of these cations can help reduce
scale formation on hot surfaces and significantly reduces the
detrimental effects of scale buildup.
[0033] It has been observed that adipic acid in hard water can also
provide a thin surface coating on many metal components,
particularly aluminum components of the cooling system. This
coating can range up to several angstroms thick. While not
considered to be limiting in any fashion, it is thought that this
coating protects the metal surface from corrosion but does not
appreciably affect heat transfer.
[0034] In addition to providing make-up water for in-use cooling
systems, frequently operators will add supplemental cooling
additives to their cooling systems. Typically, the supplemental
cooling additives include a variety of anti-corrosion agents as
specified above. It is not uncommon for an operator to "overdose"
selected components of the anti-corrosive additive. In particular,
it has been noted that nitrite levels in over-the-road diesel
engine cooling systems have been increased to levels that can be
detrimental to the aluminum and solder components of the cooling
systems. The present invention provides enhanced protection for
aluminum surfaces, thereby ameliorating some of the effects of
over-dosing. It has also been determined that molybdate and the
organic diacids provide ferrous and cylinder lining protection.
Because the anti-corrosion properties are enhanced, the
concentration of selected additives, for example, nitrite salts,
can be reduced. This reduces the likelihood that an operator will
overdose the cooling system with nitrite.
[0035] For the purpose of promoting further understanding and
appreciation of the present invention and its advantages, the
following Example is provided. It will be understood, however, that
these Examples are illustrative and not limiting in any
fashion.
EXAMPLE
[0036] Five coolant compositions listed as Examples 1-5 in Table 1
were prepared by combining the specific indicated components listed
in the table in a fully formulated base antifreeze solution that
included, in percent by weight based on the final total weight of
the final antifreeze formulation, 95% ethylene glycol, sodium
borate (0.20%); sodium molybdate (0.30%); mercaptobenzothiazole
(MBT) (0.40%, 50% active); tolyltriazole (0.20%); sodium silicate
(0.10%) as well as surfactants, scale inhibitors and defoamers
(0.05%) to provide a concentrated coolant composition. Each of the
concentrated coolant compositions was then diluted with water
having a hardness of about 300 ppm and a pH between about 8.3 and
about 8.5 to provide the coolant compositions listed as examples
1-5. These coolant compositions were then evaluated according to
ASTM D-2809 Standard Text Method for Cavitation Corrosion and
Corrosion and Erosion-Corrosion Bench Test described below.
TABLE-US-00001 TABLE 1* Concentrated Coolant Compositions Exam-
Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 Components
Adipic acid 1.0% -- -- 0.20% 0.20% Sebacic acid -- 1.00% -- -- --
Dodecanedioic -- -- 1.0% 1.4% 1.4% acid NaNO.sub.2(Nitrite) 0.36%
0.36% 0.36% 0.36% 0.20% Test Procedure ASTM D-2809 6 7 7-8 7 8
Erosion 0.4 mg 12.4 mg 87 mg 4.8 mg 4.9 mg Corrosion Bench Test
*Examples 1-5 were diluted 50:50 with water having a hardness of
300 ppm for both test procedures.
Erosion Corrosion Bench Test Procedure
[0037] This test procedure can help evaluate the effect of high
flow velocities on solder and aluminum components. A fixture
containing three preweighed bundles were placed in line of a
flowing system. The flow rate and temperature were held constant
throughout the test. The aluminum specimens were galvanically
coupled to cast iron. The test duration was seven days. At the end
of test, the weight loss due to erosion corrosion was determined on
the aluminum samples. The flow stand had a loop capable of flowing
15 gallons (57 liters) of test solution at 5-50 gal. per minute
(19-190) liters per minute), and holding 3 sets of test bundles ( 1
5/8 in. (5.1 cm) diameter radiator hose). Test fixture was capable
of holding 3 sets of test bundles (17 in. (43 cm) length).
A. Specimens and Test Solution Preparation:
[0038] Specimens: Aluminum and Cast Iron samples are of the type
used in ASTM D-1384 glassware test. Various aluminum alloys for
testing can be obtained from Metal Samples Co., Inc. Munford, Ala.
The samples were cleaned before testing by placing them in acetone
to remove processing oils. The samples were then wrapped in an
absorbent towel and placed in dessicator to dry. Test solutions
were prepared by combining antifreeze and SCA formulations in 300
ppm hard water. The hard water contained 277 mg CaCl.sub.2, 123 mg
MgSO.sub.47H.sub.2O, and 210 mg NaHCO.sub.3 per liter.
B. Test Procedure:
[0039] 1. Samples were to the nearest 0.1 mg. Then using ASTM
D-1384 hardware, test bundles were prepared in the following
sequence: teflon spacer, aluminum specimen, steel spacer, cast iron
specimen, steel spacer, aluminum specimen, teflon spacer. A brass
machine screw was inserted through the test fixture and the test
bundle in order to secure the bundle to the fixture. The aluminum
specimens in each bundle were of the same alloy.
[0040] 2. All bundles were prepared in this same sequence. The
other bundles were attached to the test fixture, making sure that
there is at least 4 inches between each bundle on the fixture.
[0041] 3. The test fixture was placed in the flow loop and the
connections secured to prevent leakage.
[0042] 4. The test solution were heated to 88.degree. C.
(190.degree. F.) and flow direct through the flow loop.
[0043] 5. The flow rate was adjusted to achieve the proper flow
velocity across the test fixture.
[0044] 6. At the completion of the test, test fixtures were removed
from flow loop.
[0045] 7. The test bundles were dissembled and cleaned in
accordance with ASTM D-1384. After drying the samples their weight
was determined to the nearest 0.1 mg.
C. Calculations
[0046] Weight loss=A-B=C, where A=Weight before test, B=Weight
after test, and C=Weight loss.
[0047] Due to the configuration of the individual test bundles,
each alloy was run in duplicate. The individual weight losses for a
single alloy agreed within 20%, and the average weight loss in
milligrams was reported. (J. A. Worden, J. F. Burke & T. Cox,
"Development of Aluminum Cooling System Components for a 10.8 liter
Diesel Engine", SAE Technical Paper Series 960643 pp. 46-59, 1996,
incorporated herein by reference).
[0048] As can be seen from Table 1, the coolant composition
containing adipic acid provides enhanced aluminum protection in the
presence of hard water. Further as can be observed for Examples 4
and 5, inclusion of adipic acid in amounts as low as 0.2 wt % based
upon the total weight of the coolant additive provides enhanced
aluminum protection. FIGS. 1 and 2 are scanned images of portions
of two aluminum coupons that were subjected to the Erosion
Corrosion Test. Coupon 10 was immersed the Example 1 coolant
formulation. Coupon 20 was immersed in the Example 3 coolant
formulation. It can be readily observed that coupon 20 has
significantly more surface erosion than coupon 10. The original
milling marks can still be seen on coupon 10 as a series of
substantially parallel lines or scratches extending across the
width of the coupon. Conversely, coupon 20 is pitted, and the
original milling marks are absent. The surface of coupon 20 was
eroded sufficiently to remove the milling marks.
[0049] Further, it is understood that the addition of adipic acid
synergistically enhances the protection of both aluminum and iron
surfaces in the presence of nitrite salts and molybdate salts. In
alternative embodiments, the addition of a combined organic acid
component that includes adipic acid and sebacic acid provides even
enhanced protection for the metal surfaces of the cooling
system.
[0050] The present invention contemplates modifications as would
occur to those skilled in the art. It is also contemplated that
compositions and processes embodied in the present invention can be
altered, rearranged, substituted, deleted, duplicated, combined, or
added to other processes as would occur to those skilled in the art
without departing from the spirit of the present invention. In
addition, the various stages, steps, procedures, techniques,
phases, and operations within these processes may be altered,
rearranged, substituted, deleted, duplicated, or combined as would
occur to those skilled in the art.
[0051] Further, any theory of operation, proof, or finding stated
herein is meant to further enhance understanding of the present
invention and is not intended to make the scope of the present
invention dependent upon such theory, proof, or finding. While the
invention has been illustrated and described in detail in the
drawings, examples and foregoing description, the same is
considered to be illustrative and not restrictive in character, it
is understood that only the preferred embodiments have been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *