Note: Descriptions are shown in the official language in which they were submitted.
CA 02409213 2002-11-18
WO 01/90232 PCT/USO1/15583
A METHOD FOR PROVIDING A FLUID COMPOSITION WITH
IMPROVED FIRE RESISTANCE
The present invention relates to a method for providing fluids with improved
fire resistance
properties. More particularly, the invention provides a method for providing
anhydrous
poly(alkylene-glycol)-based fluid compositions with Group 1 or Group 2 fire
resistance
properties, as measured by calculating a spray flammability parameter which is
representative of the heat content of a fluid.
Until recently, fire resistant fluids have typically been classified using
either a spray
flammability test or a hot-channel test. However, those skilled in the art
have long
recognized that these testing protocols do not adequately discriminate between
observable
and significant differences in the fire resistance properties of various fluid
types.
Accordingly, Factory Mutual Research Corporation of Norwood, MA (Factory
Mutual) has
developed a new testing protocol based on the heat content of a fluid as
represented by an
experimentally determined spray flammability parameter (S.F.P.). This new
S.F.P. protocol
provides a quantitative measure of the fire resistance properties of different
fluids and
allows for accurate differentiation among fluid types. Factory Mutual is
recognized by those
skilled in the art as a highly authoritative resource for determining the fire
resistance
properties of various materials, and the S.F.P. protocol is expected to be the
standard by
which fire resistant fluids will be categorized.
According to the new protocol, an experimental S.F.P. parameter is calculated
by the
following equation from experimental data:
Equation I
S.F.P. _ (1.47 x 101~~ x (Q~h
(pf) x (Tf)4 x (mf)
where: Q~h = Chemical heat release of spray flame (kilowatts)
pf = Fluid density (kilograms per cubic meter)
Tf = Fire point temperature (degrees Kelvin)
mf = Mass flow rate of the fluid (grams per second).
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The S.F.P. may also be estimated according to the following equation which
assumes 100
percent combustion efficiency:
Equation II
S.F.P. _ (1.47 x 1010 x (~ H
(pf) x (T f)4
where: ~ HT = The net heat of complete combustion (kilojoules per gram)
Using the S.F.P. protocol, fluids are classified into one of the following
groups as set forth
in Table l:
Table 1
Classification of Fluids
ClassificationS.F.P. Note
Group ( x 104
)
1 < 4.0 Unable to stabilize a spray flame, having
a normalized S.F.P.
of 4.0 x 104, or less
2 4.0 to Less flammable than mineral oil fluids,
8.0 but may stabilize a
spray flame under certain conditions, having
a normalized
S.F.P. eater than 4.0, but less than 8.0
x 104
3 > 8.0 Flammability approximating that of mineral
oil fluids,
havin a normalized S.F.P. eater than 8.0
x 104
Calculation of the estimated S.F.P. is used as a preliminary screening
procedure for fire
resistance. For example, if the objective is to determine if a fluid is Group
1 or Group 2,
and if an S.F.P. value of significantly less than 4.0 x 104 is obtained, then
the fluid will be
certified as Group 1 by Factory Mutual without further testing. However, if
the estimated
S.F.P. is close to 4.0 x 104 then the fluid must be tested experimentally to
accurately
c1 assify it in the appropriate category. A similar procedure is used to
classify a fluid
according to Groups 2 or Group 3
The present invention provides a method for providing an anhydrous
poly(alkylene-glycol)-
based fluid composition with at least Group 2 fire resistance properties.
According to the
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WO 01/90232 PCT/USO1/15583
invention, the composition is formulated with an ethylene oxidelalkylene oxide
weight
percent ratio and/or an amount of antioxidant sufficient to provide the fluid
composition
with a spray flammability parameter of less than 8.0 x 104.
More specifically, the invention provides a method for providing an anhydrous
poly(alkylene-glycol)-based fluid composition with at least Group 2 fire
resistance,
characterized by the step of
formulating the composition with at least one of an ethylene oxide/alkylene
oxide weight
percent ratio and an amount of antioxidant sufficient to provide the fluid
composition with a
spray flammability parameter of less than 8.0 x 104.
The invention further provides a method for providing a hydraulic system with
at least
Group 2 fire resistant properties, characterized by the step of
adding to the system an anhydrous poly(alkylene-glycol)-based hydraulic fluid
formulated
with at least one of an ethylene oxide/alkylene oxide weight percent ratio and
an amount of
antioxidant sufficient to provide the fluid with a spray flammability
parameter of less than
8.0 x 104.
The invention further provides a method for providing a heat treatment system
for metal
working with at least Group 2 fire resistant properties characterized by the
step of
adding to the system an anhydrous poly(alkylene-glycol)-based quenchant
formulated with
at least one of an ethylene oxide/alkylene oxide weight percent ratio and an
amount of
antioxidant sufficient to provide the quenchant with a spray flammability
parameter of less
than 8.0 x 104.
Anhydrous poly(alkylene-glycol)-based fluid compositions comprise polymers of
poly(alkylene-glycols) (PAG's) which are made from the reaction of alkylene
oxide
monomers and a nucleophilic starter, usually an alcohol. These polymers are
represented by
the following general formula:
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WO 01/90232 PCT/USO1/15583
R' R"
where:
Z = an alcohol starter with 1-20 carbon atoms, including methanol, ethanol,
propanol, isopropanol, butanol, glycerine, and sucrose. Z may also be an
amine starter such as ammonia, monoethanolamine, triethanolamine, and
diethanolamine;
R', R" = H, CH3, any aryl or C2-C16 alkyl group in any combination resulting
in a
block or random structure;
R"'= H, CH3, any aryl, ester, or C2-C16 alkyl group;
n = 5-500; and
x = 1-6
While any PAG-polymer having this general formula may be used in formulating
fluid
compositions in accordance with the present invention, these fluid
compositions are usually
formulated using ethylene oxide and/or alkylene oxide polymers. The ethylene
oxide can
range from 0 to 100 weight percent of the oxide feed, with the balance being
the alkylene
oxide monomer(s), typically propylene oxide, although other oxides such as
butylene oxide
or styrene oxide can also be used. As noted above, the sequencing of the oxide
monomers
can be either random or block.
In accordance with the present invention, fluid compositions are provided with
at least
Group 2 fire resistance by providing the composition with an ethylene
oxide/alkylene oxide
weight percent ratio of from 0:1 to 1:0. In those formulations which include
antioxidant, the
composition includes at least 0.1 weight percent antioxidant, preferably from
0.5 to 10
weight percent antioxidant, and most preferably from 1 to 2 weight percent
antioxidant.
Preferably, the fluid composition is provided with Group 1 fire resistance,
that is, with an
ethylene oxide/alkylene oxide weight percent ratio and/or an amount of
antioxidant
sufficient to provide a spray flammability parameter of less than or equal to
4.0 x 104. In
one embodiment, this is accomplished by formulating the composition with an
ethylene
oxide/propylene oxide ratio of at least 2:1 to 1:0. In a second embodiment,
Group 1 fire
resistance is provided by formulating the composition with an ethylene
oxide/propylene
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WO 01/90232 PCT/USO1/15583
oxide weight percent ratio of from 1:3 to 3:1 and with 1 weight percent to 2
weight percent
of antioxidant. In yet another embodiment, borderline Group 1/Group 2 fire
resistance is
provided by formulating the composition with an ethylene oxide/propylene oxide
weight
percent ratio of 0:1 and from 1 to 2 weight percent of antioxidant.
Fluids formulated according to the method of the invention can be used in a
number of
industrial and commercial applications where the risk of fire is a critical
concern. For
example, hydraulic system failures have, in a number of instances, resulted in
serious fires
accompanied by loss of life. Accordingly, hydraulic fluids must not only have
superior high
pressure and lubricating properties, but these fluids must also provide fire
resistance in those
applications where a significant risk of fire would result from an hydraulic
system failure.
Quenchant fluids used in heat treating systems for metalworking applications
also present a
significant risk of fire. This is particularly the case with marquenching
fluids, which are
used for the high-temperature heat treatment of crack-sensitive steel alloys.
Anhydrous poly(alkylene-glycol)-based fluid compositions formulated according
to the
invention are particularly suitable for use as hydraulic fluids. These
compositions not only
provide superior high pressure and fire resistant properties, but can also
provide superior
lubrication. In addition, it is possible to formulate fire resistant anhydrous
(PAG-based
hydraulic fluids which also exhibit good biodegradability and low aquatic
toxicity. The
fluid compositions taught by the invention are also excellent quenchants and
are therefore
particularly suitable for use in heat treating applications. These
compositions have
quenching properties equivalent to those of the specially formulated mineral
oil quenchants
typically used in the art and provide the important advantage of being fire
resistant. The
compositions can also formulated to be water soluble or biodegradable and to
provide
significantly lower sludging tendencies as compared to mineral oil quenchants.
Fluid compositions formulated in accordance with the invention may also
include additional
components depending on the particular industrial or commercial application
for which the
fluid will be used. Accordingly, these compositions may include, for example,
lubricity
modifiers, corrosion inhibitors (both ferrous and non-ferrous types), anti-
wear agents,
extreme-pressure modifiers, dyes, biocides, anti-foaming agents, wetting
agents, viscosity
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WO 01/90232 PCT/USO1/15583
modifiers, thermal stability agents and detergents.
It has been determined that the ethylene oxide/alkylene oxide content of an
anhydrous
poly(alkylene-glycol) (PAG)-based fluid composition significantly impacts the
fire
resistance properties of the composition. More specifically, it has been
discovered that by
increasing the ethylene oxide content of an anhydrous PAG-based fluid
composition, the
S.F.P. of the composition is lowered. It has also been discovered that the
addition of one or
more antioxidants to an anhydrous PAG-based fluid composition reduces the
S.F.P. of the
composition, regardless of the ethylene oxide/alkylene oxide weight percent
ratio of the
composition. The S.F.P. lowering effect provided by the antioxidant is
dependent on the
structure of the antioxidant and its concentration in the fluid composition,
at least up to a
certain concentration level. As noted previously, one or more antioxidants
rnay be used to
provide the desired level of fire resistance.
In order to determine the effects of ethylene oxide/alkylene oxide weight
percent ratio and
antioxidant selection and concentration on enhancing the fire resistant
properties of
anhydrous PAG-based fluid compositions, the S.F.P. was estimated for several
fluid
compositions using Equation II above. The fluid compositions selected for
study and the
data obtained for these fluids are summarized below in Table 2 as Examples 1-
15. Each
fluid composition consists of a base fluid having a specified ethylene
oxide/propylene oxide
(EQ/PO) weight percent ratio, or such a base fluid together with an
antioxidant. It should be
understood that while each of the fluid compositions used in Examples 1-15
includes either
ethylene oxide or propylene oxide polymers or ethylene oxide/propylene oxide
copolymers,
the invention is in no way limited in this regard, and similar results can be
expected with
other poly(alkylene-glycols) having the general formula set forth above.
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CA 02409213 2002-11-18
WO 01/90232 PCT/USO1/15583
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CA 02409213 2002-11-18
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CA 02409213 2002-11-18
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-9-
CA 02409213 2002-11-18
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10-
CA 02409213 2002-11-18
WO 01/90232 PCT/USO1/15583
UCON Lubricant LB-285 is an alcohol-started polymer of propylene oxide having
a
viscosity of 285 Saybolt Universal Seconds (SUS) at 38~C. This polymer is
available from
Union Carbide Corporation, Danbury, CT.
UCON Lubricant LB-165 is an alcohol-started polymer of propylene oxide having
a
viscosity of 165 SUS at 38~C. This polymer is available from Union Carbide
Corporation,
Danbury, CT.
UCON Lubricant 50-HP-260 is an alcohol-started copolymer containing equal
amounts by
weight of ethylene oxide and propylene oxide. The copolymer has a viscosity of
260 SUS at
0
38 C and is available from Union Carbide Corporation, Danbury, CT.
CARBO WAX TPEG-990 is a glycerin-started polymer of ethylene oxide which has a
molecular weight of 990 grams per mole. CARBOWAX TPEG-990 is available from
Union Carbide Corporation, Danbury, CT.
The data presented in Table 2 show that increasing the ethylene oxide content
of an
anhydrous PAG-based fluid composition enhances the fire resistance properties
of the fluid.
In particular, note that Examples 15, which contains 100 weight percent of
ethylene oxide
and which does not include an antioxidant, has an S.F.P. of 3.02 x 104.
Accordingly, this
PAG-based fluid composition exhibits Group 1 fire resistance properties.
Example 2 also
does not include an antioxidant and has an ethylene oxidelpropylene oxide
weight percent
ratio of 1:1. Example 2 has an S.F.P. of 4.71 x 104 and is therefore
classified only as a
Group 2 fire resistant fluid. However, the S.F.P. of the Example 2 composition
is
significantly lower than that of the Example 3 composition which is 100 weight
percent
propylene oxide.
Those skilled in the art have not heretofore appreciated that Group 1 and
Group 2 fire
resistance can be provided in an anhydrous PAG-based fluid composition solely
by
controlling the ethylene oxide to alkylene oxide weight percent ratio of the
fluid. These
fluids have been used in the past as hydraulic fluids; however, fire
resistance was achieved
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either by incorporating water in the fluid or by adding an agent which
controls the droplet
size of the fluid, as disclosed in U.S. Patent No. 5,141,663.
Incorporating water in an hydraulic fluid presents several disadvantages.
These fluids
generally exhibit inferior hydraulic pump performance as compared to anhydrous
fluids, and
they exhibit poor lubrication protection and a much greater potential for
cavitation. The
anhydrous PAG-based fluid disclosed in the '663 patent overcomes these
disadvantages.
However, as noted above, the composition requires the addition of an agent to
control the
droplet size of the fluid. Only by employing such an agent can the droplet
size and
distribution of the fluid as it is sprayed from a nozzle be controlled to
provide acceptable
fire resistance.
Quenchants including water soluble polymers are known in the art. However,
these
quenchants are often characterized by excessive cooling rates sufficient to
causes cracking
of steel. Moreover, vaporization of the water in these quenchants can
contaminate heat
treating atmospheres. The use of anhydrous fluid compositions eliminates these
potentially
severe problems. Anhydrous PAG-based fluid compositions containing 100 weight
percent
of ethylene oxide have been used in the past as quenchants on a very limited
basis.
However, neither the superior fire resistance properties of these fluids nor
the fact that fire
resistance could be provided by controlling the ethylene oxide content of the
fluid was
appreciated by those skilled in the art.
The present invention does not require the addition of water or the use of an
agent to control
droplet size. As shown in Table 2, Group 1 or Group 2 fire resistance is
achieved by
providing a sufficiently favorable ethylene oxide to propylene oxide weight
percent ratio.
More specifically, Group 1 fire resistance is achieved by providing an
anhydrous PAG-
based fluid with an ethylene oxide/propylene oxide weight percent ratio of at
least 2:1.
Anhydrous PAG-based fluid compositions having an ethylene oxide/propylene
oxide weight
percent ratio of at least l :l exhibit Group 2 fire resistance.
The data in Table 2 also demonstrate that the fire resistance properties of an
anhydrous
PAG-based fluid composition are enhanced by the addition of one or more
antioxidants,
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regardless of the ethylene oxide/propylene oxide weight percent ratio of the
composition.
Moreover, the data show that the addition of antioxidant to an anhydrous PAG-
based fluid
composition provides Group 2 fire resistance even where the composition
contains 100 wt.
percent of propylene oxide. In particular, the results shown for Examples 3, 5-
8 and 10
demonstrate that fire resistant properties approaching very close to Group 1
fire resistance
can be provided by the addition of a sufficient amount of an appropriate
antioxidant or
combination of antioxidants.
Antioxidant structure plays an important role in the S.F.P. lowering effect.
Several classes
of antioxidants have been found to be particularly effective in improving the
fire resistant
properties of PAG-based fluids. The preferred antioxidants include, phenolic
antioxidants,
phenol formaldehyde resins containing bisphenol A as a termonomer, amine-based
antioxidants such as phenyl-a-napthylamine (PANA), phenothiazine, and mixtures
of these
antioxidants. It should be understood, however, that the invention is not
limited to these
antioxidants and that other antioxidants known in the art may also be
employed. For
example, phosphite functional antioxidants such as triphenyl phosphite may be
employed;
however, the S.F.P lowering effect of these antioxidants are generally
inferior to the effect
provided by the preferred antioxidants noted above.
Examples 3, 5-8 and 10 demonstrate the effect of antioxidant structure on
S.F.P. reduction.
All of these examples employ the same anhydrous PAG-based fluid containing 100
wt.
percent of propylene glycol. The data show that phenothiazine was the most
effective
antioxidant evaluated in the study (Example 7). PANA, an amine-based
antioxidant, and
IRGANOX E-3201, a phenolic-based antioxidant available from Ciba Specialties
Chemicals
Corporation, Tarrytown, NY were both equally effective in reducing the S.F.P.
of the base
fluid (Examples 5 and 13). Triphenyl phosphite (Example 10) was the least
effective of the
antioxidants examined. Other effective antioxidants include IRGANOX L-06 and
IRGANOX 1010, both of which are amine-based antioxidants available from Ciba
Specialties Chemicals Corporation, Tarrytown, NY.
With respect to antioxidant concentration, the results in Table 2 indicate
that the S.F.P.
lowering effect provided by the antioxidant is apparent only up to a certain
concentration of
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antioxidant in the fluid composition. Additional levels of antioxidant provide
only a
marginal improvement in the fire resistance properties of the composition.
Note, in
particular, that Examples 3-5 all comprise the same anhydrous PAG-based fluid
but contain
varying amounts of the antioxidant N-phenyl alpha naphthylamine (PANA).
Examples 4
and 5 have considerably lower S.F.P. as compared to Example 3, which does not
contain
any antioxidant. However, doubling the antioxidant concentration from 1 wt.
percent in
Example 4 to 2 wt. percent in Example S provides only a marginal improvement
in fire
resistance.
Generally, the fire resistance provided by the antioxidant increases as the
ethylene oxide
content of the fluid composition increases. Thus, the lowest S.F.P. results
were obtained
with PAG-based compositions containing 100 wt. percent ethylene oxide together
with an
antioxidant, as shown by Example 11. Slightly higher S.F.P.'s, but still Group
1 fire
resistance, was provided by the use of an antioxidant in a fluid composition
containing only
50 wt. percent ethylene oxide. In cases where the anhydrous PAG-based fluid
composition
does not contain any ethylene oxide, at least 2 wt. percent of antioxidant is
preferred.
Where the fluid composition is characterized by an ethylene oxide/propylene
oxide wt.
percent ratio of from 1:3 to 3:1, the composition preferably includes from 1
wt. percent to 2
wt. percent of the antioxidant.
As discussed above, the S.F.P. in each of Examples 1-15 was estimated using
Equation II,
which assumes 100 percent combustion. Accordingly, the S.F.P. for several of
the fluid
compositions set forth in Table 2 (Examples 3-10) was derived experimentally
to determine
how closely the estimated S.F.P. values and the experimental S.F.P. values
agreed. The
results of this study are set forth below in Table 3.
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Table 3
Example Experimental Calculated
S.F.P. x 104 S.F.P. x
104
Exam 1e 6.01 6.21
3
Exam 1e 4.17 4.42
4
Exam 1e 4.14 4.33
Example 4.40 4.47
6
Exam 1e 3.96 4.18
7
Exam 1e 4.11 4.42
8
Examle9 3.36 3.52
Example 4.77 ~ 5.04
~
As shown in Table 3, the estimated S.F.P. values are close but always higher
than the
5 experimentally derived S.F.P. values. This is as expected, since Equation II
assumes 100
percent combustion. The results confirm that Equation II may be used to
provide a estimated
S.F.P. that closely approximates the experimentally derived value.
As discussed previously, anhydrous PAG-based fluid compositions prepared
according to
10 the method of the invention may be used as fire resistant hydraulic fluids,
quenchants and
lubricating fluids. However, those skilled in the art will appreciate that the
invention is in
no way limited by these particular applications and that fluids prepared by
the method taught
by the invention may be used in a wide variety of industrial and commercial
applications
where fluid compositions having Group 1 or Group 2 fire resistance are
required.
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