Application of non aqueous fluids based on alkylene glycol monoether as heat transfer agent

The present invention relates to the application of a non aqueous fluid as heat transfer agent in cooling circuits or heat exchanger heating circuits, this application being characterized in that the non aqueous fluid comprising one or more alkleneglycol monoethers of the general formulae EQU R.sup.1 O(CH.sub.2 CHR.sup.2 O).sub.m H in which m is an integer equal to 1 or 2, R.sup.1 is an alkyl radical comprising a number of carbon atoms from 4 to 8 where m=1 , or from 1 to 5 where m=2, and R.sup.2 is a hydrogen atom or a methyl radical. The present invention also relates to new compositions based essentially on alkyleneglycol monoether or monoethers, mixed with diols and/or other alkyleneglycol monoethers.

The present invention relates to the application of a non-aqueous fluid 
comprising one or more alkyleneglycol monoethers as heat transfer agent in 
cooling circuits or heat exchanger heating circuits, and also to new 
compositions for use as a non-aqueous heat transfer fluid. 
It is known that heat transfer fluids which consist principally of aqueous 
mixtures based on a glycol, such as ethyleneglycol or propyleneglycol, can 
be used in heat exchangers, such as for example in cooling circuits of an 
internal combustion engines. Recently new internal combustion engines have 
been developed in the automobile industry with a view to reducing fuel 
consumption. This reduction in consumption can be obtained for example by 
decreasing the weight of the automobile vehicle and in particular the 
engine block, by the use of light alloys based on magnesium, or by 
increasing the energy efficiency of the engine which operates at 
relatively high temperatures which may be as much as 200.degree. C., for 
example. The heat transfer fluids known hitherto, however, are no longer 
suitable for these new engines and the conditions in which they are now 
used. In particular, they are unable to provide effective protection 
against corrosion for light alloys based on magnesium, because of the 
corrosivity with respect to magnesium. Furthermore, these heat transfer 
fluids have a boiling temperature which is generally below 110.degree. C., 
a temperature which is too low and therefore incompatible with the 
operating conditions of the new high-output engines. Furthermore, at low 
temperatures they have too high a viscosity to be suitably used as heat 
transfer agents or else exhibit a freezing point between 0.degree. and 
-40.degree. C., which necessitates the use of an antifreeze agent. 
It has now been found that it is possible to use a heat transfer fluid 
which is capable on its own of solving all these difficulties at once. 
This fluid may be employed, avoiding the drawbacks referred to above, in 
heat exchanger circuits, especially cooling circuits, of internal 
combustion engines having parts made of alloys based on magnesium which 
operate at high temperatures. 
The object of the present invention is therefore the application of a 
non-aqueous fluid as heat transfer agent in cooling circuits or heat 
exchanger heating circuits, the application being characterised in that 
the non-aqueous fluid comprises one or more alkyleneglycol monoethers, of 
the general formula 
EQU R.sup.1 O (CH.sub.2 CHR.sup.2 O).sub.m H 
in which m is an integer equal to 1 or 2, R.sup.1 is an alkyl radical 
comprising a number of carbon atoms from 4 to 8 when m=1, or from 1 to 5 
when m=2, R.sup.2 is an hydrogen atom or methyl radical. 
It has been found that non-aqueous fluids comprising alkyleneglycol 
monoethers, especially monoethyleneglycol or diethyleneglcyol monoethers 
or monopropyleneglycol or di-proplyeneglycol monoethers, such as those 
referred to above, are capable of being used as heat transfer agents in 
cooling circuits or heat exchanger heating circuits operating in a 
comparatively broad temperature range which may, for example, go from 
-60.degree. C. to +200.degree. C. and in particular -50.degree. C. to 
+170.degree. C. These non-aqueous fluids, in fact, have the advantage both 
of a low viscosity at temperatures as low as -40.degree. C., and excellent 
thermal stability at temperatures as high as +170.degree. C. or 
+200.degree. C., and, suprisingly, corrosivity which is negligieable or 
nil with respect to magnesium or its alloys under such varied conditions 
of use. Thus it has been found that it is possible to use a fluid which 
surprisingly possesses all these properties in itself as heat transfer 
agents in cooling circuits such as those of internal combustion engines 
comprising parts of light alloy based on magnesium and operating at high 
temperatures, and in addition this fluid does not require the use of an 
anti-freeze agent. 
Moreover, the non-aqueous fluids have a comparatively satisfactorily 
compatibility with respect to elastomers or rubbers which are present in 
the various parts of the cooling circuits, for example in the form of 
gaskets or flexible connections. Such behaviour may appear all the more 
unexpected since it is known that bringing elastomers or rubbers into 
contact with compounds comprising an ether function generally produces 
harmful effects, such as the swelling of these materials. It is also 
important to note that these non-aqueous fluids are not regarded as 
flammable products as defined by the criteria employed by the legislation 
of the European Communitys in directive no. 67/548/EEC of the June 27th 
1967 relating to the packaging and labelling of chemical substances. In 
fact the flash point of the non-aqueous fluids is above 55.degree. C. and 
generally above 70.degree. C. Furthermore the miscibility with water of 
these fluids is generally sufficient to avoid the formation of two 
separate phases during any contact of these fluids with water. 
The non-aqueous fluids employed according to the present invention comprise 
one or more alkyleneglycol monoethers of the general formula 
EQU R.sup.1 O (CH.sub.2 CHR.sup.2 O).sub.m H 
in which m is an integer equal to 1 or 2. When m is equal to 1, R.sup.1 is 
a normal or branch-chained alkyl radical comprising 4 to 8 carbon atoms 
for example an n-butyl, n-hexyl, ethyl-2 butyl or ethyl-2 hexyl radical. 
When the radical R.sup.1 comprises less than 4 carbon atoms, it is 
observed that in this case the alkyleneglycol monoethers cannot be used as 
basic constituents of the non-aqueous fluid, because of their low boiling 
point and low flash point, and also because of a certain amount of 
corrosivity which they may show with respect to magnesium or its alloys. 
On the other hand, when a non-aqueous fluid comprising at least one 
alkyleneglycol monoether having a radical R.sup.1 comprising more than 8 
carbon atoms is used, it is found that this fluid has both poor 
compatability with respect to elastomers or rubbers, too high a viscosity 
at low temperatures and a mediocre miscibility with water. 
When in the general formula 
EQU R.sup.1 O (CH.sub.2 CHR.sup.2 O).sub.m H 
m is equal to 2, R.sup.1 is a normal or branch-chained alkyl radical 
comprising 1 to 5 carbon atoms. When the number of carbon atoms is over 5, 
it is found that in this case the alkyleneglycol monoethers cannot be used 
as non-aqueous heat transfer fluids, especially at low temperatures, in 
view of their high viscosity at -40.degree. C., and the fact that they 
generally have poor compatibility with respect to elastomers or rubbers 
and also mediocre miscibility with water. 
Moreover, when alkyleneglycol monoethers of the general formula 
EQU R.sup.1 O (CH.sub.2 CHR.sup.2 O).sub.m H 
in which m is over 2 are used as the essential constituent of non-aqueous 
heat transfer fluids, it is found that these fluids have numerous 
drawbacks in the application according to the present invention, in 
particular a certain amount of thermal instability at high temperatures, 
too great a viscosity at low temperature and a mediocre miscibility with 
water. 
According to the present invention, therefore it is preferable to use one 
or more of the alkyleneglycol monoethers chosen from amongst the 
monomethyl ether of diethyleneglycol, monoethylether of diethyleneglycol, 
monopropyl ether of diethyleneglycol, monobutylether of diethyleneglycol, 
monomethylether of dipropyleneglycol, monoethylether of dipropyleneglycol, 
monoproplyether of dipropylenegycol and monobutylether of 
dipropyleneglycol. More especially it is preferred to use the 
monoethylether of diethyleneglycol. 
It is possible to add to the non-aqueous heat transfer fluids diols and/or 
alkyleneglycol monoethers which are different from those used according to 
the present invention. In this way one can obtain new non-aqueous heat 
transfer fluid compositions, which are especially well suited to certain 
operating conditions of internal combustion engines, such as for example 
relatively high temperatures, or suited to certain atmospheric conditions 
such as very low ambient temperatures, these new compositions are capable 
of affording a more specific protection against the corrosion of certain 
metals, and/or against an improved compatibility in respect of certain 
elastomers or rubbers. 
The present invention therefore also relates to new non-aqueous heat 
transfer fluid compositions, characterised in that they comprise 
constituents (a), (b), (c) employed in the mixtures (a)+(b), or (a)+(c), 
or (a)+(b)+(c), these constituents being (a) 100 parts by weight of one or 
more alkyleneglycol monoethers of the general formula 
EQU R.sup.1 O (CH.sub.2 CHR.sup.2 O).sub.m H 
in which m is an integer equal to 1 or 2, R.sup.1 is an alkyl radical 
comprising a number of carbon atoms from 4 to 8 when m=1 or from 1 to 5 
when m=2, and R.sup.2 is a hydrogen atom or a methyl radical, (b) 0 to 30 
parts, preferably 2 to 15 parts by weight of one or more alkyleneglycol 
monoethers of the general formula 
EQU R.sup.3 O (CH.sub.2 CHR.sup.4 O).sub.n H 
in which is n is an integer from 1 to 6, R.sup.3 is an alkyl radical 
comprising a number of carbon atoms: 
from 1 to 3, when n=1, 
from 6 to 8, when n=2, or 
from 1 to 8 when n has a value from 3 to 6, 
and R.sup.4 is a hydrogen atom or a methyl radical, (c) 0 to 40 parts, 
preferably 5 to 20 parts by weight of one or more diols of the general 
formula 
EQU HO (CH.sub.2 CHR.sup.5 O).sub.p H 
in which p is an integer from 1 to 3 and R.sup.5 is a hydrogen atom or a 
methyl radical. 
Thanks to these new compositions, in this way one can obtain non-aqueous 
heat transfer fluids whose properties may to a certain extent be 
controlled at will by the addition of appropriate quantities of 
constituents (b) and/or (c) to the essential constituent (a). 
In particular, compositions comprising: 100 parts by weight of one or more 
alkyleneglycol monoethers chosen from amongst the monomethylether of 
diethyleneglycol, the monoethylether of diethyleneglycol, the 
monopropylether of diethyleneglycol, the monobutylether of 
diethyleneglycol, monomethyether of dipropyleneglycol, the monomethlyether 
of dipropyleneglycol, the monopropylether of dipropylenegylcol and the 
monobutlyether of dipropyleneglycol, preferably the monoethylether of 
diethyleneglycol, and 0 to 40 parts, preferably 5 to 20 parts by weight of 
ethyleneglycol or propyleneglycol may be used. 
It is found that compositions containing in particular or diols, according 
to the definition of the constituents (c) refer to above, have an improved 
compatibility with respect to elastomers or rubbers, such as 
ethylene/propylene copolymers, butadiene/acrylonitrile copolymers or 
"butyl" rubbers. 
These new compositions may be prepared by mixing the constituent (a), (b) 
and/or (c) by known methods for mixing liquids, at a temperature which may 
be between 0.degree. and 100.degree. C., preferably at ambient temperature 
(20.degree. C.). 
It is also possible to add to the non-aqueous fluids or compositions of the 
invention additives in themselves known, such as for example corrosion 
inhibiting agents, such as tolyltriazole or a potassium nitrate, basic 
compounds which can serve as a reserve of alkalinity, such as 
alkanolamines and anti-foaming or anti-precipitating agents. These 
additives must be soluble in non-aqueous fluids or in the composition and 
are generally employed in a quantity at most equal to 5% by weight in 
relation to the non-aqueous fluids or the said compositions. In this way 
fluids or compositions of the invention are obtained which are ready for 
use and which are particularly well adapted to the cooling circuits of 
internal combustion engines, in which circuits these fluids or these 
compositions come in contact with various metals, alloys, elastomers or 
rubbers, making up the various parts of these circuits. 
The non-restrictive examples below illustrate the present invention.

EXAMPLE 1 
A non-aqueous heat transfer fluid (A) ready for use is prepared by mixing 
at ambient temperature (20.degree. C.): 100 part by weight of 
monoethlyether of diethyleneglycol of the formula 
EQU C.sub.2 H.sub.5 O (CH.sub.2 CH.sub.2 O).sub.2 H 
0.5 part by weight of aminomethylpropanol 0.2 part by weight of 
tolyltriazole 0.5 part by weight of diphenylolpropane, and 0.2 part by 
weight of potassium nitrate. 
The results of the measurements of the physical properties performed on the 
non-aqueous fluid (A) are set out in Table I, in particular the boiling 
and freezing temperatures, the viscosity at -40.degree. and +20.degree. 
C., the miscibility with water at 20.degree. C. and the compatibility with 
respect to elastomers and rubbers, such as ethlyene/proplyene compolymers 
(EPR), "butyl" rubbers and butadiene/acrylonitrile copolymers. 
Tests of resistance to corrosion of metallic test pieces are carried out by 
immersion in the non-aqueous fluid (A). The quality of the metals or 
alloys used and also all the operating conditions for these tests are 
defined by the Standard ASTM - D - 1384/70. Corrosion is demonstrated by 
the variation in weight of each test piece (expressed in milligrams) at 
the end of a given period. The results of the corrosion measurements are 
given in Table II. 
According to the analysis of these results as a whole, it is found that the 
non-aqueous fluid (A) may be used conveniently as a heat transfer agent in 
a cooling circuit of an internal combustion engine operating at high 
temperature, which may reach 180.degree. C., under atmospheric conditions 
where the ambient temperature may drop to -40.degree. C., without showing 
marked corrosiveness in respect of magnesium or its alloys. 
EXAMPLE 2 
A non-aqueous heat transfer fluid composition (B) ready for use is prepared 
by mixing at ambient temperature (20.degree. C.): 100 parts by weight of 
monoethylether of diethyleneglycol 11.3 parts by weight of ethyleneglycol 
0.5 part by weight of aminomethylpropanol 0.2 part by weight of 
tolyltriazole 0.5 part by weight of diphenylolpropane and 0.2 part by 
weight of potassium nitrate. 
The results of the measurement of the physical properties performed on 
composition (B) are set out in Table I. In addition, in Table II the 
results of the corrosion measurements performed in a manner identical to 
that in Example 1 are given, except for the fact that instead of using 
non-aqueous fluids (A) composition (B) is used. 
From the analysis of these results as a whole it is found that composition 
(B) may be employed conveniently as a heat transfer agent in a cooling 
circuit of an internal combustion engine operating at a high temperature 
which may reach 180.degree. C., under atmospheric conditions where the 
ambient temperature may drop to -40.degree. C., without showing marked 
corrosivity with respect to magnesium or its alloys and without causing a 
certain deterioration in elastomers and rubbers such as ethylene/propylene 
(EPR), butadiene/acrylonitrile copolymers and "butyl" rubbers. 
TABLE I 
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Properties of non-aqueous heat transfer fluid compositions 
Compatibility 
Non-aqueous 
Boiling 
Freezing 
Viscosity at 
Viscosity at 
Miscibility 
with respect to 
Fluid Temperature 
Temperature 
-40.degree. C. 
+20.degree. C. 
with water 
elastomers and 
Composition 
(.degree.C.) 
(.degree.C.) 
(centistokes) 
(centistokes) 
(20.degree. C.) 
rubbers.sup.(1) 
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A 202 -78 23 4.5 complete 
good 
B 193.5 -60 35.2 6.6 complete 
very good 
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.sup.(1) Ethylene/propylene copolymer (EPR), butadiene/acrylonitrile 
copolymer, "butyl" rubber. 
TABLE II 
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Corrosion measurements performed according to the standard 
ASTM-D-1384/70 
Non-aqueous 
Fluid Variations in weight expressed in mg/test piece 
Composition 
Copper 
Solder 
Brass 
Steel 
Cast Iron 
Aluminium 
Magnesium 
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A -5 -2 -5 -1 -1.5 -2 -2.5 
B -6 -1 -5 -0.5 
-2 -3 -2 
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