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Description  |
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FIELD OF THE INVENTION
This invention relates to lubricants used with refrigerants in compression
refrigeration and air-conditioning systems. More particularly, it relates
to lubricants for use with saturated hydrocarbons having 1-4 carbon atoms
that are partially or fully substituted with at least one atom of chlorine
or fluorine, and have a normal boiling point of -80.degree. C. to
+50.degree. C. Specifically, this invention relates to lubricants for use
with tetrafluoroethanes, e.g. 1,1,1,2-Tetrafluoroethane (HFC-134a), and
1,1,2,2-Tetrafluoroethane (HFC-134), etc. and of lesser importance,
pentafluoroethane (HFC-125). These compounds are being considered as
replacements for dichlorodifluoromethane (CFC-12), particularly in
automotive air conditioning systems. The lubricants of this invention are
not only completely miscible over the full operating temperature range for
automotive air-conditioning with HFC-134a and the like, but are also
completely miscible with CFC-12 over this range. Hence, they may be used
with CFC-12 in the same systems during the transition from CFC-12 to
HFC-134a.
BACKGROUND OF THE INVENTION
Refrigeration systems that use CFC-12 as the refrigerant generally use
mineral oils to lubricate the compressor. (See for example the discussion
in Chapter 32 of the 1980 ASHRAE Systems Handbook.) CFC-12 is completely
miscible with such oils throughout the entire range of refrigeration
system temperatures, i.e. -45.degree. C. to 65.degree. C. In automotive
air-conditioning, paraffinic and naphthenic oils of about 500 SUS
viscosity at 100.degree. F. are usually used with CFC-12. These oils have
"pour points" below -20.degree. C. and viscosities of about 55 SUS at
210.degree. F. and are completely miscible with the CFC-12 refrigerant
over the range of temperatures from -10.degree. C. to 100.degree. C.
Consequently, oil which dissolves in the refrigerant travels through the
refrigeration loop in the air conditioning system and returns with the
refrigerant to the compressor. It does not separate during condensation,
although it may accumulate because of the low temperature when the
refrigerant is evaporated. At the same time, this oil which lubricates the
compressor will contain some refrigerant which, in turn, may affect its
lubricating properties.
When substituting HFC-134a or HFC-134 for CFC-12 in these refrigeration
systems, it would be desirable to be able to use the same oils as used
with CFC-12. It would not require any substantial change in equipment nor
any significant changes in conditions used for the system. If lubricant
separates from refrigerant during operation of the system, serious
problems may result, i.e. the compressor could be inadequately lubricated.
This would be most serious in automotive air-conditioning systems because
the compressors are not separately lubricated and a mixture of refrigerant
and lubricant circulate throughout the entire system. Unfortunately,
however, the mineral oils are substantially immiscible with the
tetrafluoroethanes.
Two recent publications of ASHRAE discuss the problems associated with
separation of lubricants and refrigerants. These are "Fundamentals of
Lubrication in Refrigerating Systems and Heat Pumps" Kruse and Schroeder
ASHRAE Transactions Vol. 90 Part 2B, pps. 763-782, 1984 and "Evaluation of
Lubricants for Refrigeration and Air-Conditioning Compressors", Spauschus,
ibid pps. 784-798.
In summary, refrigerants which are not completely miscible with an oil in
the full range of mixture compositions and operating temperatures may
become miscible or immiscible as the temperature is raised or lowered from
room temperature. The areas of immiscibility may assume a variety of
shapes, i.e. parabolic or non-parabolic. As a parabola, the curve of
miscibility temperature vs. percent oil in the mixture, may have its open
or concave portion facing the low or high temperatures. The closed or
convex-portion of the parabolic curve identifies, respectively, the
maximum or minimum temperature above or below which the refrigerant and
the lubricating oil are completely miscible. These temperatures are
referred to as the maximum or minimum "consolute temperatures." Beside
parabolas, these curves can assume skewed parabolic shapes or curves of
varying slope wherein immiscibility occurs above or below the curve.
One of the objects of this invention is to provide a combination of
lubricating oil and refrigerants such as tetrafluoroethane, e.g. HFC-134a,
where the area of miscibility encompasses the full range of temperature
and composition encountered in compression refrigeration, i.e. complete
miscibility occurs for all compositions in the range of -45.degree. C. to
at least 20.degree. C., preferably to 100.degree. C., the critical
temperature of HFC-134a. Another object is to provide a process for using
such compositions in compression refrigeration.
PRIOR ART
U.S. Pat. No. 4,248,726, issued Feb. 5, 1981, and U.S. Pat. No. 4,267,064,
issued May 12, 1981, both to Nippon Oil Company et al, relate to the use
of a polyglycol oil such as polyoxypropylene glycol (or an alkyl ether
thereof) having a viscosity index of at least 150 and a glycidyl ether
type epoxy compound as a high viscosity refrigeration oil composition for
halogen-containing refrigerants. These polyglycol/glycidyl ether
compositions are disclosed for use with Freon.RTM.11, 12, 13, 22, 113,
114, 500 and 502; and as being "particularly effective" with Freon.RTM.12
or 22.
Research Disclosure 17486 entitled "Refrigeration Oil by E. I. du Pont de
Nemours and Company discloses polyalkylene glycols such as Ucon.RTM.
LB-165 and Ucon.RTM. LB-525 sold by Union Carbide Corporation, for use
with HFC-134a. These glycols are polyoxypropylene glycols that are
mono-functional and are prepared from propylene oxide initiated with
n-butanol. The publication states that these combinations of oil and
refrigerant are miscible in all proportions at temperatures at least as
low as -50.degree. C. and are thermally stable in the presence of steel,
copper and aluminum at 175.degree. C. for about six days.
U.S. Pat. No. 4,755,316, issued July 5, 1988, to Allied-Signal Inc. also
relates to the use of polyalkylene glycols. However, these glycols are at
least difunctional with respect to hydroxyl groups and contain at least
80% propylene oxide units relative to the total, the remaining 20% may
derive from ethylene or butylene oxide or esters, olefins and the like
which are polymerizable with propylene oxide. It should be noted that only
100% oxypropylene units in the difunctional PAGs are exemplified in this
patent.
SUMMARY OF THE INVENTION
The present invention is based on the discovery that the use of a
sufficient amount to lubricate, usually 10-20% by volume for automotive
use, and in some situations as high as 50% by volume, of at least one
fluorinated hydrocarbon, saturated or unsaturated, in which the weight
ratio of fluorine-to-carbon is from about 0.5 to 5, having an SUS
viscosity at 100.degree. F. of at least 50 and a pour point of less than
about -20.degree. C., hereafter referred to as an "HFC oil," will be
completely miscible with tetrafluoroethanes and pentafluoroethane, usually
80-90% by volume of the tetrafluoroethanes, HFC-134 and HFC-134a, the
pentafluoroethane, HFC-125, and other saturated hydrocarbons having 1-4
carbon atoms that are partially or fully substituted with at least one
atom of chlorine or fluorine and a normal boiling point of -80.degree. C.
to +50.degree. C., or blends thereof, in the range of temperatures from
-40.degree. C. to at least 20 .degree. C., preferably to 100.degree. C.,
the critical temperature of HFC-134a.
The preferred HFC oils include polymers of R.sub.f (CH.sub.2).sub.n
CH.dbd.CH.sub.2 where "R.sub.f " may be anywhere from CF.sub.3 - to
C.sub.10 F.sub.21 - or higher, preferably C.sub.6 F.sub.13 -, C.sub.8
F.sub.17 -, C.sub.10 F.sub.21 - and higher, and n=0-2, but preferably n=1;
and copolymers of R.sub.f (CH.sub.2).sub.n CH.dbd.CH.sub.2 with a variety
of vinyl compounds, e.g. butyl vinyl ether, acrylonitrile and the like. A
particularly useful HFC oil in this category is where C.sub.6 F.sub.13 -
represents 60%, C.sub.8 F.sub.17 - represents 30% and C.sub.10 F.sub.21 -
and higher represents the remainder of "R.sub.f " and n=1. It has also
been found that these preferred HFC oils are completely miscible in the
CFC's particularly in CFC-12.
Another category of HFC oil for use with the tetrafluoroethanes in the
present invention involves the products resulting from grafting
hexafluoropropylene or a similar perfluorocarbon onto long chain aliphatic
hydrocarbons, C.sub.8 or greater. These are described in U.S. patent
application Ser. No. CH-1686 filed in the name of H. Cripps.
The weight ratio of refrigerant to the lubricant, the "HFC oil", may be
anywhere from 99/1 to 1/99, preferably 99/1 to 70/30. The viscosity of
these oils may range from 50 to 3000 SUS at 100.degree. F., but for most
commercial uses, from 100 to 1200 SUS at 100.degree. F.
It is known that the use of an appropriate amount of an "extreme pressure
(EP) additive" improves the lubricity and load-bearing characteristics of
oils and, thus, would improve the quality of the refrigerant-lubricant
compositions. EP additives for use in the invention are included among
those disclosed in Table D of U.S. Pat. No. 4,755,316. A preferred one is
an organic phosphate; SYN-O-AD.RTM. 8478, a 70%/30% blend of tri
(2,4,6-tri-t-butyl phenyl) phosphate/triphenyl phosphate, manufactured by
the Stauffer Chemical Company.
EP additives may also be used in conjunction with some of the antiwear
additives, oxidation and thermal stability improvers, corrosion
inhibitors, viscosity index improvers, detergents and anti-foaming agents
disclosed in Table D of U.S. Pat. No. 4,755,316. These additives may also
be partially or fully fluorinated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As stated previously, the tetrafluoroethanes, e.g. HFC-134a, HFC-134 and
the pentafluoroethane, HFC-125, particularly HFC-134a have physical
characteristics which allow substitution for CFC-12 with only a minimum of
equipment changes in compression refrigeration. They could be blended with
each other, as well as with other refrigerants, including CFC-12(CCl.sub.2
F.sub.2), HCFC-22(CHClF.sub.2), HFC-152a(CH.sub.3 CHF.sub.2),
HCFC-124(CHClFCF.sub.3), HCFC-124a(CHF.sub.2 CClF.sub.2),
HCFC-142b(CH.sub.3 CClF.sub.2), HFC-32(CH.sub.2 F.sub.2),
HFC-143a(CH.sub.3 CF.sub.3), HFC-143(CHF.sub.2 CH.sub.2 F), and FC-218
(CF.sub.3 CF.sub.2 CF.sub.3); and for purposes of the present invention
such blends are not excluded. However, only those blends of
tetrafluoroethane or pentafluoroethane with other refrigerants which are
miscible with the lubricants of this invention in the range of -40.degree.
C. to about +20.degree. C. are included.
HFC-134a, the preferred tetrafluoroethane refrigerant, may be prepared by
any of the methods disclosed in the prior art; e.g., U.S. Pat. Nos.
2,745,886; 2,887,427; 4,129,603; 4,158,675; 4,311,863; 4,792,643 and
British Nos. 1,578,933 and 2,030,981.
The preferred HFC oil is the polymerization product of R.sub.f
(CH.sub.2).sub.n CH.dbd.CH.sub.2 where the number of carbon atoms in the
R.sub.f group is 2 to 20, preferably 6-10, and n=0 or 1. The most
preferred is a member of this group wherein R.sub.f =C.sub.6 F.sub.13
(60%), C.sub.8 F.sub.17 (30%), and C.sub.10 F.sub.21 and higher (the
remainder) and n=0 or 1.
These may be prepared by any of the processes disclosed in U.S. Pat. Nos.
4,606,832; 4,668,749; and 4,673,712. A polymerization process employing a
peroxide initiator is preferred with a reaction temperature between
50.degree. C. and 200.degree. C.
These HFC oils may be varied to yield viscosities ranging from 50 to 3000
SUS at 100.degree. F. Furthermore, the monomer(s) may be copolymerized
with any of a variety of vinyl compounds including but not limited to
vinyl ethers, acrylates, methacrylates, acrylonitrile, vinyl ethoxylates
or a halogenated monomer to modify the lubricating properties. The HFC
oils may be blended with other lubricants, e.g. perfluorocarbons, to
modify viscosity and/or lubrication properties.
Specifically, the lubricants used in the compositions of this invention,
and in the invented method for providing lubrication in compression
refrigeration and air-conditioning equipment have the the following
characteristics:
Viscosity at 100.degree. F.
50 to 3000 SUS, preferably 100 to 1200 SUS, particularly about 500 SUS for
automotive air-conditioning
Pour Point <-20.degree. C., preferably -20.degree. C. to about -50.degree.
C. and -30.degree. C. for the 100 SUS and 500 SUS oils, respectively
Solubility or miscibility range
100% from 100.degree. C. to (a) less than -40.degree. C. for 1-99 weight
percent of HFC-134a in mixture with the HFC lubricant of 100.degree. F.
viscosities of 50 SUS to 2500 SUS (b) less than -30.degree. C. for the
preferred divinyl ether copolymer, and (c) less than -35.degree. C. for
the preferred 520 SUS blend.
Four-ball wear test with a specific set of steel balls. Scar wear and
coefficient of friction equal to or slightly higher than that for the oils
currently used with CFC-12 in automotive air-conditioning, i.e., 0.37 mm
scar wear and 0.07 friction coefficient when saturated with CFC-12 at
atmospheric pressure.
"Falex" (load failure test) with a specific type of steel for the V-block
and pin. The fail load equal to or greater than that for the
CFC/refrigerant oil combinations, i.e., 1300 lbs. when saturated with
CFC-12 at atmospheric pressure.
1. Solubility of Refrigerant in Lubricants
Six ml. blends of refrigerant and lubricant were used for the solubility
studies. Generally, the mixtures contained 30, 60, and 90 wt. %
refrigerant. These air-free mixtures were contained in sealed Pyrex.RTM.
tubes (7/16" I.D..times.5.5", ca. 12.5 cc capacity). The
refrigerant/lubricant solubilities were determined by completely immersing
the tube in a bath at each test temperature for a minimum of 15 minutes
and providing agitation to facilitate mixing and equilibration. The
accuracy of determining the temperatures when the refrigerant/lubricant
blend became either miscible or immiscible was about .+-.2.degree. C. The
refrigerant/lubricant blends were called immiscible when the blend
acquired and retained "schlieren" lines; formed floc; or formed two liquid
layers. These solubility tests were run from 93.degree. to -50.degree. C.
Tests were not run above 93.degree. C. for safety reasons. It is assumed
that if the blend of HFC-134a/oil is soluble to 93.degree. C., it will
still be soluble at 100.5.degree. C., the critical temperature of
HFC-134a.
2. Stability of Refrigerant and Lubricant
Three ml. of refrigerant and 0.3 ml. of lubricant plus coupons (steel
1010/copper/aluminum 1100-23/8".times.1/4".times.1/16", 120-grit surface
finish) were charged and sealed in a Pyrex.RTM. tube (7/16"
I.D..times.5.5", ca. 12.5 cc volume) under anaerobic conditions. The
specimens were tied together at the top end with copper wire with
copper-wire rings between the metals to separate the metals at the top
end. The tubes were stored vertically at 268.degree. C. for 11.8 days.
Afterwards, the tube contents were examined for appearance changes. The
refrigerants were then transferred to gas-sampling bulbs for analysis by
gas chromatography for the decomposition products of the refrigerant i.e.,
HFC-143 (the decomposition product of HFC-134a) or HCFC-22 (CFC-12
decomposition product). These results were then converted to their
equivalents in terms of HF and HCl generated.
3. Lubricity
a. Four-ball Wear Test
The procedure is described fully in ASTM D4172. The method was modified as
follows: A load of 20 Kg at 1200 RPM was put on the steel 52100 balls
immersed in 10 ml. of lubricant. The refrigerant, HFC-134a or CFC-12, was
bubbled through a Teflon.RTM. capillary tube into the lubricant at the
rate of 0.75 standard cu. ft./hr. to provide one atmosphere of pressure of
refrigerant gas over the lubricant and a gas-saturated lubricant.
b. Falex Pin/V-Block Load-to-Failure Test D3233. The V-Block was made of
AISI C-1137 steel (HRC-20 to 24 hardness, 5 to 10 microinches surface
finish). The test pin was made of AISI 3135 steel (HRB-87 to 91 hardness,
5 to 10 microinches surface finish). These tests were run with refrigerant
gas bubbling through the oil as in the "Four-ball Wear Test".
4. Viscosity and Viscosity Slope
a. Viscosity is a property that defines a fluid's resistance to shearing
force. It is expressed in terms of absolute viscosity, kinematic viscosity
or Saybolt Seconds Universal viscosity (SSU), depending on the method by
which it is determined. Conversion from SSU to mm.sup.2 /s (centistokes)
can be readily made from tables contained in ASTM D-445, but it is
necessary to know the density to convert kinematic viscosity to absolute
viscosity. Refrigeration oils are sold in viscosity grades, and ASTM has
proposed a system of standardized viscosity grades for industry-wide usage
(D-2422).
Viscosity decreases as the temperature increases; and increases as the
temperature decreases. The relationship between temperature and kinematic
viscosity is represented by:
log log (v+0.7)=A+B log T (Equation 1)
where
v=kinematic viscosity, mm.sup.2 /s (CST)
T=thermodynamic temperature (kelvin)
A,B=constants for each oil
This relationship is the basis for the viscosity temperature charts
published by ASTM and permits a straight line plot of viscosity over a
wide temperature range. This plot is applicable over the temperature range
in which the oils are homogeneous liquids.
b. Viscosity Slope is a measure of the amount of change in viscosity
experienced by an oil with change in temperature. This ratio is "B" in
Equation 1 above; and is usually different for different oils.
5 Pour Point
Any oil intended for low temperature service should be able to flow at the
lowest temperature likely to be encountered. The procedure for determining
pour point is described in ASTM D-97.
The invention will be more clearly understood by referring to the examples
and controls which follow:
EXAMPLE 1 HFC OIL
This example represents the best mode known for preparing and using the
preferred HFC oil, i.e., the polymerization product of R.sub.f
--(CH.sub.2) CH.dbd.CH.sub.2, with HFC-134a in compression refrigeration.
Specifically, this HFC oil was prepared by adding 100 grams of the R.sub.f
(CH.sub.2) CH.dbd.CH.sub.2 to a reaction vessel. The vessel was heated to
110.degree. C. and sparged with nitrogen for 1 hour. The sparging
apparatus was removed and replaced by a nitrogen head. To the solution in
the reaction vessel was added 12.5 grams of
t-butyl-peroxyisopropylcarbonate (75% solution in mineral spirits) in one
portion. The solution was then heated at 110.degree. C. for about 18
hours. The reaction was monitored by 1H NMR until the olefin peaks between
sigma 5 and 6 ppm disappeared. The vessel was cooled, equipped for vacuum
distillation and the volatiles removed at a pot temperature of 60.degree.
C. and a pressure of 10 torr. The resulting 90-100 grams of yellow liquid
was analyzed to be the aforementioned polymerization product
##STR1##
1H-NMR spectrum analysis of the product revealed that the chemical shifts
of the starting material disappeared and a broad multiplet was formed for
the product. The starting material, gave the following spectral lines:
6.0-5.7 (m, 1H); 5.6-5.3 (m, 2H); 3.05 (doublet of triplets, 2H, J=20 Hz,
J=6.6 Hz). The product gave a broad multiplet between 3.0-0.9 ppm. IR
analysis showed absorbances at 3050-2850 cm.sup.-1 (CH.dbd.CH.sub.2) and
(CH.sub.2 stretches); 1400-1000 cm.sup.-1 (CF.sub.2 stretching). 13C - NMR
shows several peaks for the product in the range from 123 to 19 ppm, but
there is a clear absence of the peaks corresponding to the starting
monomer at 126 (triplet) and 123 ppm. The average molecular weight was
determined by Vapor Phase Osmometry to be 3200.
The viscosity and pour point of the product were 1,000 SUS at 100.degree.
F. and less than -20.degree. C., respectively. Viscosities ranging from
440 to 2540 SUS at 100.degree. F were also made by using process
variations. Since the latter oil had a viscosity of 9.6 SUS at 210.degree.
F., the viscosity slope (Equation 1) is -4.14. This compares favorably
with the slope of -4.23 for a naphthenic oil used with CFC-12 in
automotive air-conditioning. This oil's pour point and 40.degree. C. and
100.degree. C. viscosities are: -23.degree. C., 525 SUS and 55 SUS,
respectively.
These low to high viscosity HFC oils were found to be completely miscible
with HFC-134a from at least -40.degree. to 93.degree. C., the highest
temperature run in the solubility tests. The presence of 1.3 wt. % of
SYN-O-AD.RTM. 8478 EP additive in the high viscosity oil raised the minimum
miscibility temperature from -40.degree. to -35.degree. C. SYN-O-AD.RTM.
is a product of the Stauffer Chemical Company. Further, since CFC-12 is
also completely miscible from -40.degree. to 93.degree. C., the HFC oil
may be used interchangeably in compressor refrigeration.
Other commercial or developmental oils, which are described in the control
Examples in Tables I and II, lack the required solubility (complete
miscibility from -10.degree. to 100.degree. C.) to be acceptable
lubricants for automotive air-conditioning. Table II includes the
Suniso.RTM. 5GS naphthenic and BVM-100N paraffinic oils currently used
with CFC-12 in automotive air-conditioning.
The lubricity results with the HFC oil of this example, as measured by the
"Four-ball wear test" and the "Falex" pin/V-block, load-to-failure test
are summarized in Tables III and IV along with other oils. The HFC oil
compares very favorably with the naphthenic and paraffinic oils currently
used with CFC-12 in automotive air-conditioning.
The stability of HFC-134a or CFC-12 plus the HFC oil and metals is also
superior to the naphthenic and paraffinic oils (Table V). The key to the
visual-effect ratings in the table are: 0 - no change, 1 - very very
slight, acceptable change, 2 - very slight, borderline change, 3 - slight,
but unacceptable change, 4 - moderate, unacceptable change, and 5 - severe
change.
EXAMPLE 2 - HFC OIL MONOMER/BUTYL VINYL ETHER (BVE) COPOLYMER
This example involves preparing and using HFC oils that are copolymers
i.e., the copolymerization products of R.sub.f --CH.dbd.CH.sub.2 and
nC.sub.4 H.sub.9 OCH.dbd.CH.sub.2, with HFC-134a in compression
refrigeration.
Specifically, the copolymer HFC oils were prepared by adding 70-95 grams of
R.sub.f --CH.dbd.CH.sub.2 and 30-5 grams of butyl vinyl ether to a
reaction vessel, and then repeating the procedure of Example 1.
1H-NMR spectrum analysis of the product revealed that the chemical shifts
corresponding to the olefinic protons, 6.5-5.0 ppm, disappeared and broad
peaks appeared between 3.0-1.0 ppm in the spectra. The 13C NMR showed
peaks for the products between 123 and 19 ppm. Also, the starting olefin
peaks for R.sub.f CH.dbd.CH.sub.2 were gone, i.e., 127 (triplet) and 126
(triplet) ppm. The IR shows absorbances at 3000-2850 cm.sup.-1 (CH.sub.2
stretching); 1400-1000 cm.sup.-1 (CF.sub.2 stretching).
The range of oil viscosities and the solubilities of these oils in HFC-134a
are summarized in Table VI. The acceptable composition range for butyl
vinyl ether in the copolymer is about 1 to 30 wt. %, the preferred range
is about 1 to 10 wt. %.
EXAMPLE 3 - HFC OIL BLENDS WITH OTHER OILS
HFC oils of different viscosities may be blended to adjust for a variety of
intermediate viscosities. An HFC oil may also be blended with other oils
to obtain a specific viscosity as well, especially if the second oil is
also completely soluble in HFC-134a. A specific example of a second oil
is: 1,1,1,2,2,3,3,4,4,5,5,6,6 - tridecafluoro-7 hexadecene (TDFH) which
has a 100.degree. F. viscosity of 34 SUS, a pour point of -17.degree. C.
and is completely miscible in HFC-134a from 93.degree. to -17.degree. C. A
mixture of the HFC oil of Example 1 with a viscosity of 1800 SUS at
100.degree. F. with the TDFH oil, containing 9.1 wt. % of the latter
yielded an oil with viscosities of 520 SUS and 55 SUS at 100.degree. and
210.degree. F., respectively. This yields a viscosity slope of -4.21 which
compares favorable with the -4.23 slope for the naphthenic oil used with
CFC- 12 in automotive air-conditioning. Its solubility characteristics are
shown in Table VII where it is shown to be miscible from 93.degree. C. to
at least -35.degree. C.
An HFC oil/TDFH--89.3/10.7 wt. % blend was made to obtain a 525 SUS
viscosity at 100.degree. F. to test its lubrication properties. Table VIII
shows the blend does not surpass the control oil when saturated with
refrigerant at atmospheric pressure in the Four-ball wear test, but does
surpass the control in the Falex test. An EP additive should enhance the
results of the first test.
Other classes of oils which may be blended with the HFC oil are partially
or fully fluorinated hydrocarbons.
TABLE 1
______________________________________
SOLUBILITY OF HFC-134a WITH COMMERCIAL
FLUORINATED OILS
(Test Range 93.degree. to -50.degree. C.)
Miscible Range (.degree.C.) for Indicated
Concentrations (Wt. %) of
Expt. HFC-134a
No. Lubricant 30% 60% 90%
______________________________________
Control A
500 SUS blend,
93 to 8 93 to 7 93 to -4
Halocarbon
700/95-6.7/93.3
wt. % (a)
Control B
150 SUS, 93 to 0 93 to 10
93 to 20
Krytox .RTM. GPL
Blend (b,c)
Control C
480 SUS, 93 to 10 93 to 20
93 to 20
Krytox .RTM. GPL
Blend (b,c)
Control D
417 SUS, 93 to 5 93 to 15
93 to 15
Fomblin .RTM. Y
25/5 (b,d)
Control E
417 SUS 93 to 5 93 to 28
75 to 28
Fomblin .RTM.
Z-15 (b,d)
Control F
300 SUS, 93 to 15 93 to 22
93 to 22
Demnum .RTM.
S-65 (b,d)
______________________________________
(a) Polychlorotrifluoroethylene oil. A product of Halocarbon Products
Corporation.
(b) A perfluorinated poly alkyl ether oil
(c) A product of E. I. du Pont de Nemours and Co.
(d) A product of Montefuos, Division of Montedison Group
(e) A product of Daikin, Industries Ltd.
TABLE II
______________________________________
SOLUBILITY OF HFC-134a WITH AVAILABLE
MISCELLANEOUS REFRIGERANT OILS
Miscible Range (.degree.C.) for
Indicated Concentrations
(Wt %) of HFC-134a
Expt. in Lubricant
No. 30% 60% 90%
______________________________________
Expt. Dipentaerythritol
Esters of Fatty Acids (c)
Control G
240 SUS -50+ -4+ 40+
Control H
290 SUS -44+ -17+ 70+
Expt. PEG Esters
of Fatty Acids (d)
Control I
144 SUS -21+ 54 (a) 54 (a)
Control J
620 SUS -4+ 4+ 70+
Control K
830 SUS -6+ 70+ 70+
Naphthenic Oils (e)
Control L
Suniso .RTM. 5GS (500 SUS,
54 (a) 54 (a) 54 (a)
38% aromatic)
Control M
Witco 500 (500 SUS)
54 (a) 54 (a) 54 (a)
Control N
Expt. Oil (520 SUS,
54 (a) 54 (a) 54 (a)
47% aromatic)
Control O
Expt. Oil (529 SUS,
54 (a) 54 (a) 54 (a)
75% aromatic)
Paraffin Oil (f)
Control P
BVM-100N (500 SUS)
54 (a) 54 (a) 54 (a)
Alkyl Benzene
Control Q
Zerol 300 (300 SUS)
54 (a) 54 (a) 54 (a)
(g)
Control R
DN600 (125 SUS) (h)
54 (a) 54(a) 54 (a)
Control S
Atmos HAB15F 55+ Ins (b)
Ins (b)
(78 SUS) (i)
Silicone Oils
Controls T,
L-45 Oils (163, 231
U,V & 462 SUS) (j)
______________________________________
+ Soluble at and above shown temperature.
(a) Perhaps it is soluble somewhere above shown temperature.
(b) Completely insoluble from 93 to -50.degree. C.
(c) Hercules
(d) CPI Engineering
(e) Witco Chemical Company
(f) BVM Associates
(g) Shrieve Chemical Company
(h) Conoco
(i) Nippon Oil KK
(j) Union Carbide
TABLE III
__________________________________________________________________________
LUBRICITY OF LUBRICANTS UNDER ONE ATMOSPHERE OF
REFRIGERANT GAS PRESSURE IN A FOUR-BALL WEAR TEST
AT 225.degree. F.
100.degree. F.
Ball Coefficient
Expt. Refrig- Visc.
Scar Wear*
of
No erant Lubricant
(SUS)
(mm) (a)
Friction* (b)
__________________________________________________________________________
1 HFC-134a
HFC oil**
1000
0.221 0.058
2 CFC-12
" 0.221 0.051
3 None " 0.409 0.072
Control X
CFC-12
Napthenic
525
0.373 0.072
Control Y
None " 0.618 0.050
Control Z
CFC-12
Paraffinic
500
0.368 0.071
Control A'
None " 0.505 0.056
Control B'
CFC-134a
Krytox .RTM.
1247
0.511 0.080
143AC
Control C'
None Krytox .RTM.
0.336 0.076
143AC
__________________________________________________________________________
(a) .+-. 0.028 standard deviation
(b) .+-. 0.006 standard deviation
*The smaller the better
**The HFC oil prepared in Example 1
TABLE IV
______________________________________
LOAD-CARRYING ABILITY OF LUBRICANTS UNDER
ONE ATMOSPHERE OF REFRIGERANT GAS PRESSURE
IN FALEX PIN/V-BLOCK TEST
100.degree. F.
Fail Torque
Expt. Visc. Load at Fail
No. Gas Lubricant (SUS) (lbs.)*
(in.-lbs.)*
______________________________________
4 HFC-134a HFC oil** 1000 2250 34
5 CFC-12 " " 2250 43
6 None " " 2250 50
Control D'
CFC-12 Naphthenic
525 1250 24
Control E'
None " " 750 13
Control F'
CFC-12 Paraffinic
500 1300 26
______________________________________
*The larger the better
**The HFC oil prepared in Example 1
TABLE V
__________________________________________________________________________
STABILITY OF HFC-134a IN CONTACT WITH
LUBRICANT PLUS COUPLED STEEL-1010/COPPER/
ALUMINUM-1100 AT 268.degree. F. FOR 11.8 DAYS
(Approximately equal to 10 years of car life)
Cl.sup.- or F.sup.- *
Expt. Refrig- Generated
Visual-Effect Rating
No. erant Lubricant
(ppm) Liquid
Steel
Cu Al
__________________________________________________________________________
7 HFC-134a
HFC oil**
<0.2* 0 0 0 0
8 CFC-12
" 8 0 1 (a)
0 1 (b)
Control G
CFC-12
Naphthenic
423 4 (c)
3 (d)
2 (f)
2 (g)
Control H
CFC-12
Paraffinic
-- 0 3 (e)
0 0
__________________________________________________________________________
(a) Very very slight tarnish 30% liquid phase
(b) Trace pitting <1% of surface
(c) Brown color plus moderate black precipitate
(d) Brown deposit/gray film 25%/75% of surface plus moderate deposit of
solids at liquidgas interface (LGI)
(e) Slight copper plating plus gray film 100% of surface
f Dark tarnish 25% (f) moderate deposit at LGI
(g) Very slight etched plus moderate deposit at LGI
*No HFC134a decomposed
**The HFC oil prepared in Example 1
TABLE VI
__________________________________________________________________________
SOLUBILITY OF HFC-134a WITH TELOMER B OLEFIN/
BUTYL VINYL ETHER (BVE) COPOLYMERS
Test Range: 93 to -50.degree. C.
Wt. % 100.degree. F.
BVE in
Viscos-
Wt. %
Expt.
Copoly-
ity HFC in
Temperature Range (.degree.C./.degree.C.)
No. mer (SUS)
HFC/oil
Cloudy(a)
Hazy Soluble(b)
__________________________________________________________________________
9 5 1,640
30 -- -- 93/-33
60,90 -- -- 93/-45
10 10 310 30,60 -- 93/-30
--
90 -- -- 93/-30
11 20 330 30,60 -- 93/-40
--
90 -- 93/-30
--
12 30 280 30 93/80 80/-40
--
60 -- 93/-38
--
90 -- 15/-30
93/-15
__________________________________________________________________________
(a) opaque, white
(b) clear solution
TABLE VII
______________________________________
SOLUBILITY OF HFC-134a WITH AN OIL BLEND OF
HFC OIL/TDFH OIL - 89.3/10.7 WT. %
Test Range: 93 to -50.degree. C.
Wt. % Temperature
Expt. HFC-134a in Range
No. HFC-134a/Oil (.degree.C.)
Comments
______________________________________
13 30 93 to -45 Slight haze
60 93 to 10 Clear solution
10 to -40 Slight haze
90 93 to -38 Clear solution
______________________________________
TABLE VIII
______________________________________
LUBRICITY OF HFC OIL/TDFH - 89.3/10.7 WT. %
BLEND UNDER ONE ATMOSPHERE PRESSURE OF
REFRIGERANT GAS
HFC/TDFH Naphthenic
Oil (520 SUS) (a)
Oil (525 SUS (b)
Expt. No. Control
14 I'
______________________________________
Four-ball Wear Test
Scar Wear (mm) (c)
0.510 0.373
Coefficient of 0.075 0.072
Friction (d)
Falex Test
Fail Load* (lbs)
1780 1250
Torque at Fail* (in. lbs.)
40 24
______________________________________
(a) Under HFC134a
(b) Under CFC12
(c) .+-. 0.028 standard deviation
(d) .+-. 0.006 standard deviation
*The larger the number, the better
* * * * *
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