Note: Descriptions are shown in the official language in which they were submitted.
26171~ 2 ~ 9 ~
Title: LIQUID COMPOSITIONS CONTAINING CAR~OXYLIC ESTERS
Field of the Invention
This invention relates to liquid compositions comprising at least one
fluorine-containing hydrocarbon, and at least one lubricant. More particularly, the
invention relates to liquid compositions uæful as refrigeration liquids.
Backeround of the Invention
Use of chlorofluorocarbons, generally referred to in the industry as CFCs, has
been diminishing in recent years because of demands of environmentalists for thereduction, if not a complete ban, on the use of CFCs, due to the detrimental effect
of CFCs on the stratosphere's ozone layer. Examples of CFCs include CFC-13
which is chlorotrifluoromethane, CFC-12 which is dichlorodifluoromethane, and
CFC-113 which is 1,2,2-trifluoro-1,1,2-trichloroethane.
The problem of finding a safe replacement for CFC refrigerants and
foam-blowing agents has been difficult to solve. Several replacement candidates have
been suggested as alternatives to the fully halogenated hydrocarbons, and these
include halogenated hydrocarbons containing at least some hydrogen atoms such asHCFC-22 which is difluorochloromethane, HCFC-123 which is
1,1-dichloro-2,2,2-trifluoroethane, HFC-134a which is 1,1,1,2-tetrafluoroethane and
HCFC-141b which is 1,1-dichloro-1-fluoroethane.
The ozone depletion potential of these proposed substitutes is significantly less
than the ozone depletion potential of the previously used CFCs. The ozone depletion
potential is a relative measure of the capability of the material to destroy the ozone
layer in the atmosphere. HCFC-22 and HFC-134a generally are recommended as
being candidates in refrigerant applications, and HFC~134a is particularly attrac~ive
because its ozone depletion potential has been reported as being zero.
In order for any of the replacement materials to be useful as refrigerants, the
materials must be compatib'e with the lubricant utilized in the compressor. The
presently used refrigerants such as CFC-12 are readily compatible with mineral
lublicating oils which are utilized as the lubricant in air-conditioner compressors.
The above-described refrigerant candidates, however, have different solubility
2 2~9~
characteristics than the refrigerants presently in use. For eDple, mineral lub-
ricating oil is incompatible (i.e., insoluble) with HFC-134a. Such incompatibility
results in unacceptable compressor life in compression-type refrigeration equipment
including refrigerators and air-conditioners including auto, home, commercial and
industrial air-conditioners.
In order to perform as a satisfactory refrigeration liquid, the mixture of
refrigerant and lubricant must be compatible and stable over a wide temperature range
such as from about 0C and above 80C. For some uses, it is generally desirable for
the lubricants to be soluble in the refrigerant at concentrations corresponding to the
ratios customary in the environment of use, e.g. about 5 % to 15 %, over a
temperature range from -30, or preferably -40C, or below, to 80C or above. Inaddition to thermal stability, the refrigeration liquids must have acceptable viscosity
characteristics which are retained even at high temperatures, and the refrigeration
liquid should not have a detrimental effect on materials used as seals in the
compressors.
Compositions comprising a tetrafluoroethane and polyoxyalkylene glycols are
discussed in U.S. Patent 4,755,316. The compositions are useful in refrigerationsystems. Refrigeration oils are described in U.S. Patents 4,248,726 and 4,267,064
which comprise mixtures of a polyglycol and 0.1 to 10% of glycidyl ether type epoxy
compounds, or epoxidized fatty acid monoesters, and optionally, epoxidized vegetable
oik The lubricating oils are reported to be useful in refrigerators using a
halogen-containing refrigerant such as Freons 11, 12, 13, 22, 113, 114, 500 and 502
(available from DuPont), and in particular with Freon 12 or 22.
U.S. Patent 4,431,557 describes fluid compositions comprised of a fluoro-
and chloro-containing refrigerant, a hydrocarbon oil, and an alkylene oxide additive
compound which improves thc thermal resistance of the oil in the presence of therefrigerant. Examples of hydrocarbon oils include mineral oil, alkyl benzene oil,
dibasic acid ester oil, polyglycols, etc. The composition may contain other additives
including load-carrying additives such as phosphorus acid esters, phosphoric acid
esters, etc. Examples of fluorocarbon refrigerants include R-l l, R-12, R-113~ R-114,
R-500, etc.
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U.S. Patent 4,428,854 describes absorption refrigerant compositions for use
in refrigeration systems comprising 1,1,1,2-tetrafluoroethane and an organic solvent
capable of dissolving the ethane. Among the solvents disclosed are organic amides,
acetonitrile, N-methyl pyrroles, N-methyl pyrrolidine, N-methyl-2-pyrrolidone,
nitromethane, various dioxane derivatives, glycol ethers, butyl formate, butyl acetate,
diethyl oxalate, diethyl malonate, acetone, methyl èthyl ketone, other ketones and
aldehydes, triethyl phosphoric triarnide, triethylene phosphate, triethyl phosphate, etc.
Stabilized absorption compositions comprising (a) a halogenated hydrocarbon
refrigerant, (b) a liquid absorbent of a polyethylene glycol methyl ether, and ~c) at
least one stabilizer are described in U.S. Patent 4,454,052. Exarnples of stabilizers
include phosphate esters, epoxy compounds, and organotin compounds. The
polyethylene glycol methyl ether-type compounds are of the general formula
CH3~0~(CH2H40)nR
wherein n is an integer of 1 to 6, and R is H, CH3- or CH3CO-. A variety of
halogenated hydrocarbons are described including 1, l-difluoromethane, 1,1,1 ,2-tetra-
fluoroethane, etc.
U.S. Patent 4,559,154 relates to absorption heat pumps utilizing as working
fluid, a saturated fluorohydrocarbon or fluorohydrocarbon ether having from 3 to 5
carbon atoms. Solvents reported to be useful with such fluorohydrocarbons include
ethers such as tetraglyme, amides which cm be lactams such as the N-alkyl
pyrrolidones, sulfonamides and ureas including cyclic ureas.
~mma~:~lnventiQn
This invention relates to a liquid composition comprising (A) at least one
fluorine-containing hydrocarbon containing one to three carbon atoms; and (B) at least
one carboxylic ester of (I) a neo hydroxy compound selected from the group
consisting of (i) a neo hydroxy compound with two or three hydroxyl groups, (ii) a
mixture of neo hydroxy compounds having an average of less than about 3.5 hydroxyl
groups per hydroxy compound, (iii) a neo hydroxy compound having five or more
4 ~ $ 5 ~
hydroxyl groups per hydroxy compound, and (iv) a mixture of neo hydroxy
compounds having an average greater than 4.5 hydroxyl groups per hydroxy
compound, and (II) a combinatiorl of (a) a monocarboxylic acylating agent havingfour or five carbon atoms and (b) a monocarboxylic acylating agent having from
S about 7 to about 15 carbon atoms, provided that when (I) is (i) or ~ii) then greater
than 55% of the ester groups are derived from aIa), and provided that when (I) is
(iii) or (iv) then greater than 55 % of the ester groups are derived from (IIb). These
liquid compositions may additionally contain an alkyl phosphite, an alkyl phosphonic
acid ester, and/or a nitrogen-containing heterocycle.
Liquid compositions also are described wherein the fluorine-containing
hydrocarbons also contain other halogens such as chlorine. Methods of lubricating
refrigeration systems are also described. The liquid compositions are useful
particularly as refrigeration liquids in refrigerators and air~onditioners including
automotive, home, commercial, and industrial air-conditioners.
The carboxylic esters derived from neo hydroxy compounds (i) and (ii),
especially (i), have low viscosities, such as around 10-20 cSt at 40C, while having
excellent solubility. the esters derived from (iii) and (iv), especially (iii), have high
viscosities, such as around 150-350 cSt at 40".
Detailed Description of the ~nvention
Throughout this specification and claims, all parts and percentages are by
weight, temperatures are in degrees Celsius, and pressures are at or near atmospheric
pressure unless otherwise clearly indicated.
As used in this specification and in the appended claims, the terms
"hydrocarbyl" and "hydrocarbylene~ denote a group having a carbon atom directly
attached to the polar group and having a hydrocarbon or predominantly hydrocarbon
character within the context of this invention. Such groups include the following:
(1) Hydrocarbon groups; tha~ is, aliphatic, (e.g., alkyl or alkenyl), alicyclic
(e.g., cycloalkyl or cycloalkenyl), and the like, as well as cyclic groups wherein the
ring is completed through another portion of the molecule (that is, any two indicated
substituents may together form an alicyclic group). Such groups are known to those
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s
skilled in the art. E~amples include methyl, ethyl, octyl, decyl, octadecyl,
cyclohexyl, etc.
(2) Substituted hydrocarbon groups; that is, groups containing
non-hydrocarbon substituents which, in the context of this invention, do not alter the
predominantly hydrocarbon character of the group. Those skilled in the art will be
aware of suitable substituents. Examples include halo, hydroxy, alkoxy, etc.
(3) Hetero groups; that is, groups which, while predominantly hydrocarbon
in character within the context of this invention, contain atoms other than carbon in
a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be
apparent to those skilled in the art and include, for example, nitrogen, oxygen and
sulfur.
In general, no more than about three substituents or hetero atoms, and
preferably no more than one, will be present for each 10 carbon atoms in the
hydrocarbyl group.
Terms such as "alkyl", "alkylene", etc. have meanings analogous to the above
with respect to hydrocarbyl and hydrocarbylene.
The term "hydrocarbon-based" also Ihas the same meaning and can be used
interchangeably with the term hydrocarbyl when referring to molecular groups having
a carbon atom attached directly to the polar group.
The term "lower" as used herein in conjunction with terms such as
hydrocarbyl, hydrocarbylene, alkylene, alkyl, alkenyl, alkoxy, and the like, is
intended to describe such groups which contain a total of up to 7 carbon atoms, per
se, and include methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl groups.
Viscosity, unless otherwise indicated, is kinematic viscosity and is measured
by ASTM D-2270.
For purpose of this invention, equivalent weight of polyol is determined by
dividing the formula weight of the polyol by the number of hydroxyl groups.
Equivalents of polyol is determined by dividing the amount of polyol by its equivalent
weight. For polycarboxylic acylating agents or anhydrides, the equivalent weight is
determined by dividing the formula weight of the acylating agent or anhydride by the
2 ~ 5 ~
number of carboxylic groups which forrn esters. For e~carnple, an anhydride
contributes two carboxyl groups which can forrn ester. Therefore, ~e equivalent
weight of anhydride, such as succinic anhydride, would be the formula weight of the
anhydride divided by the number of carboxyl group. For succinic anhydride, the
number is t~vo. Of course, those of skill in the art will appreciate that an excess of
acylating agent, i.e., more than a single equivalent, may be used.
When a compound or component is indicated herein as being "soluble", the
compound or component is soluble in the liquid compositions of the invention
comprising the fluorine-containing hydrocarbon and the lubricant. For example, acompound or component is considered "soluble" so long as it is soluble in the liquid
compositions, even though it may be insoluble in the fluorine-containing hydrocarbon
per se.
The term "consisting essentially of" refers to compositions that include the
ingredients listed in the claim as well as other ingredients that do not materially affect
the basic and novel characteristics of the liquid compositions.
(A) Fluorine-Containin~ Hydrocarbon.
The liquid compositions of the present invention comprise at least one
fluorine-containing hydrocarbon. That is, the fluorine-containing hydrocarbons
contain at least one C-H bond as well as C-F bonds. In addition to these two
essential types of bonds, the hydrocarbon also may contain other carbon-halogen
bonds such as C-CI bonds. Because the liquid compositions of the present invention
are primarily intended for use as refrigerants the fluorine-containing hydrocarbon
preferably contains one to three, or to two carbon atoms, and more preferably two
carbon atoms
As noted above, the fluorine-containing hydrocarbons useful in the liquid
compositions of the present invention may contain other halogens such as chlorine.
However, in one preferred embodiment, the hydrocarbon contains only carbon,
hydrogen and fluorine. These compounds containing only carbon, hydrogen and
fluorine are referred to herein as fluorohydrocarbons or hydrofluorocarbons. The
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hydrocarbons containing chlorine as well as fluorine and hydrogen are referred to as
chlorofluorohydroGlrbons or hydrochlorofluorocarbons.
Specific exarnples of the fluorine containing hydrocarbons useful in the liquid
compositions of the present invention include HCFC-22 (CHClF2), HCFC-123
S (CHCl2CF3), HCFC-141b (CH3CCl2F), and HFC-134a (CH2FCF3).
Examples of other fluorine-containing hydrocarbons which may be useful in
the liquid compositions of the present invention include trifluoromethane (HFC-23),
l,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a),
2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124), 1-chloro-1,1,2,2-tetrafluoroethane
(HCFC-124a), 1-chloro-1,1-difluoroethane (HCFC-142b), and
1,1,2,2-tetrafluoroethane (HFC-134). Other refrigerants such as perfluoropropane(HFC-218), perfluorocyclopropane ~HFC-216), perfluoropropylene oxide, 1,3-
perfluoro propylene oxide and pentafluorodimethyl ether may also be used with the
lubricant. In the refrigerant art, the fluorohydrocarbons are often identified maely
with the prefix "R" in place of the above letters. For example HFC-23 is R-23,
HCFC-124 is R-124, etc.
In general, fluorine-containing hydrocarbons which are useful as refrigerants
are fluoromethanes and fluoroethanes boiling at a relatively low temperature at
atmospheric pressure, e.g., below 30C. Mixtures of fluorine-containing
hydrocarbons may be used, and the amount of each fluorohydrocarbon in the mixture
may be varied as desired. Examples of fluorohydrocarbon mixtures useful as (A)
include: 142(b)/22; 134(a)/23; 22/124/152(a), etc. The useful fluorocarbon refriger-
ants serve to transfer heat in a refrigeration sys~em by evaporating and absorbing heat
at a low temperature and pressure, and by releasing heat on condensing at a higher
temperature and pressure.
The amount of fluorine-containing hydrocarbon is the level typically used for
the refrigeration system. The liquid compositions of the present invention generally
contain from about 10%, or about 20% up to about 90%, or to about 85% of the
fluorine-containing hydrocarbon. In one embodiment, the fluorine-containing
hydrocarbon is present in an amount from about 45%, or about 50%, or about 55%
2 ~
B
up to about 90%, or to about 80%, or to about 75% by weight of the liquid
composition. More generally, the liquid compositions will comprise from about 50%
to about 99% by weight of the fluorine-containing hydrocarbon. ln another embodi-
ment, ~e liquid compositions contain ~rom about 70% to about 99% by weight of the
fluorine-containing hydrocarbon. When the fluorine-containing hydrocarbon is used
at levels greater than 50% by weight of the lubricant, then the liquid compositions are
generally suited for use as automotive and commercial and industrial refrigeration
systems.
In one embodiment, the fluorine-containing hydrocarbon is present in an
amount from about 10%, or about 25%, or about 30% up to about 55%, or to about
50%, or ~o about 45% by weight of the lubricant. When the fluorine-containing
hydrocarbon is present in an amount less than about 45 %, then the liquid
compositions are generally suited for household refrigeration systems.
The carboxylic ester utilized as component (B) in the liquid compositions of
the present invention are reaction products of (I) a neo hydroxy compound and (II)
one or more carboxylic acylating agents, e.g. acids, anhydrides, or the lower esters
thereof such as methyl, ethyl, etc.). The neo hydroxy compound are selected fromthe group consisting of (i) a neo hydroxy compound with two or three hydroxyl
groups, (ii) a mixture of neo hydroxy compounds having an average of less than
about 3.5 hydroxyl groups per hydroxy comvound, (iii) a neo hydroxy compound
having five or more hydroxyl groups per hydroxy compound, and (iv) a mix~ure of
neo hydroxy compounds having an average of greater than 4.5 hydroxyl groups per
hydroxy eompound.
l~sters may be prepared from any hydroxy compound, such as a
polyhydroxy compound. These hydroxy compounds include glycols and triols, such
as butanediol, hexanediol, glycerol, butanetriol, and hexanetriol. However, the
inventor has discovered that esters derived from neo alcohols provide beneficialproperties to the liquid compositions of this invention. The neo hydroxy compound
(i) contains two or three hydroxyl groups, preferably three hydroxyl groups. These
9 2~9~85~
hydroxy compounds include glycols and triols, sueh as neopentyl glycol, and
preferably trimethylolalkanes. Trimethylolalkanes include trimethylolmethane,
trimethylolethane, trimethylolpropane and trimethylolbutane. A preferred
trimethylolaLtcane is trimethylolpropane.
In another embodiment, the neo hydroxy compound is a mixture of neo
hydroxy compounds having an average of less than 3.5 hydroxyl groups per hydroxycompound. The average number of hydroxyl groups per compound is determined by
dividing the total number of hydroxyl groups in the mixture by the total number of
hydroxy compound in the mixture. For instance, a (50:50) molar mixture of
trimethylolpropane and neopentyl glycol has 2.5 hydroxyl groups per hydroxy
compound. A (75:25) molar mixture of trimethylolbutane and neopentylglycol has
an average of 2.75 hydroxyl groups per hydroxy compound. Any mixture of neo
hydroxy compounds may be used provided that the resultant esters are soluble in the
liquid compositions of the present invention. In one embodiment, the mixture is
prepared from neo hydroxy compound having from two to about four, preferably to
about three hydroxyl groups per hydroxy compound. I:xamples of neo hydroxy
compound which may be used to form the mixture (ii) include pentaerythritol,
neopentylglycol, and trimethylolalkanes, as described above. Example of molar
mixtures of neo hydroxy compound includes trimethylolpropane and pentaerythritol(80:20), trimethylolpropane and trimethylolethane (50:50), and trimethylolbutane and
hexanetriol (50:50).
In another embodiment, the neo hydLoxy compound is (iii) neo hydroxy
compound having five or more hydroxyl groups per hydroxy compound. These neo
hydroxy compounds generally conhain from about 5, or about 6 up to about 12, or to
about 10, or to about 8 hydroxyl groups per hydroxy compound. Examples of these
compounds include dipentaerythritol, tripenherythritol, and di-trimethylolpropane.
Although not part of the present invention, esters may be prepared form triglycerol.
In another embodiment, the neo hydroxy compound is (iv) a mixture of neo
hydroxy compound having an average of greater than 4.5 hydroxyl groups per
hydroxy compound. The determination of this average is the same as described for
2 ~
mL~ture (ii) above. Examples of (iv) include dipentaerythrhol and tripentaerythritol
(75:25), trimethylolpropane and dipentaerythritol (80:20), neopentylglycol and
tripentaerythritol (20:80), pentaerythritol and tripenherythritol (75:25), and
pentaerythritol and dipentaerythritol (60:40).
The above neo hydroxy compounds are reacted with ~II) a combination of (a)
a monocarboxylic acylating agent having four or five carbon atoms and (b) a
monocarboxylic acylating agent having from about 7 to about 1$ carbon atoms,
provided that when (I) is (i) or (ii) then greater than 55%, or greater than 57%, or
greater than 59% of the ester groups are derived from (IIa), and provided that when
(I) is (iii) or (iv) then greater than 55% of the ester groups are derived from (IIb).
The monocarboxylic acylating agents are preferably aliphatic acylating agents. In one
embodiment, monocarboxylic acylating agents are linear or branched. The branchedacylating agents may be methyl-branched acylating agents, which are generally
referred to as "iso" acylating agents. The acylating agents may also be alpha-,alpha-,
disubstituted acylating agents, or "neo" acylating agents. In one embodiment, the
monocarboxylic acylating agent (IIa) may be isobutyric, valeric, 2-methylbutyric, or
neopentanoic acid or anhydride. Isopentanoic acid, commercially available from
Union Carbide, is a mixture of valeric acid and 2-methyl-butanoic acid with an
approximate weight ratio of (66:34). In another embodiment, the monocarboxylic
acylating agent may be neo pentanoic acid, available from Exxon Chemical Company.
The monocarboxylic acylating agent (llb) generally contains from about 7, or
about 8 up to about 15, or to about 12, or to about 10 carbon atoms. Like
monocarboxylic acylating agents (Ila), mono~lrboxylic acylating agents (llb) may be
linear or branched, including "iso" and "neo" branched acylating agents. Examples
of these acylating agents include n-octanoic acid, neoheptanoic acid, neodecanoic
acid, 2,2,4-trimethylpentanoic acid, 2-hexyldecanoic acid, isostearic acid, 2-methyl-
hexanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethylhexanoic acid, 2,2,4-
trimethylpentanoic acid, isononanoic acid, isoheptanoic acid, isodecanoic acid,
neoheptanoic acid, neodecanoic acid, and ISO Acids and NEO Acids available from
Exxon Chemical Company, Houston, Texas USA. ISO Acids are isomer mixtures
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of branched acids and include commercial mi~ctures such as ISO Heptanoic Acid, ISO
Octanoic Acid, and ISO Nonanoic Acid, as well as developmental products such as
ISO Decanoic Acids and ISO 810 Acid. Of the ISO Acids, ISO Octanoic acid and
ISO Nonanoic acid are preferred. Neo acids include commercially available n~ixtures
such as NEO Pentanoic Acid, NEO Heptanoic Acid, and NEO Decanoic Acid, as
well as developmental products such as ECR-909 (NEO Cg) Acid, and ECR-903
(NEO C~2~4) Acid and commercial mixtures of branched chain carboxylic acids suchas the mixture identified as NEO 1214 acid from Exxon.
The carboxylic esters of the liquid compositions are prepared by reacting at
least one carboxylic acylating agent with at least one neo hydrcxy compound. Theformation of esters by the interaction of carboxylic acylating agents and alcohols is
acid catalyzed and is a reversible process which can be made to proceed to
completion by use of a large amount of alcohol or carboxylic acylating agent, or by
removal of the water as it is formed in the reaction. If the ester is formed by
transesterification of a lower molecular weight carboxylic ester, the reaction can be
forced to completion by removal of the low molecular weight alcohol or acid formed
as a result of a transesterification reaction. The esterification reaction can be
catalyzed by either organic acids or inorganic acids. Examples of inorganic acids
include sulfuric acids and acidified clays. A variety of organic acids can be utilized
including paratoluenesulfonic acid, and acidic resins such as Amberlyst 15, etc.Organometallic catalysts include, for example, tetraisopropoxy orthotitanate.
The following examples describe the esters of the liquid composition of the
present invention.
Example 1
A reaction vessel is charged with 2145 parts (16 moles) of trimethylolpropane
and 2305 parts (16 moles) of 2,2,4-trimethylpentanoic acid. The mixture is heated
to 150C and the temperature is maintained for 2-1/2 hours. Distillate (260 ml.) is
collected. The reaction mixture is cooled to 145C where 3098 parts (35.2 moles)of isobutyric acid is added to the reaction vessel over 1-1/2 hours. The reaction
mixture cools to 100C after the addition of the isobutyric acid. SE-100 aromatic
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solvent, commercially available from Ohio Solvents (100 ml.), is added to the
reaction vessel. The reaction mixture is heated to 145C and the temperature is
maintained for 17 hours. The reaction mixture is vacuum stripped at 145C, 20 mmHg for 18 hours. The neutralization acid number of the residue after vacuum
stripping is 0.15. The reaction mixture is vacuum stripped for an additional 4 hours
and the residue is filtered through a mixture of diatomaceous earth and aluminumoxide. The filtrate has a kinematic viscosity of 13.82 at 40C and 3.1 at 100C.The residue has a 0.03 total acid number.
Example 2
A reaction vessel is charged with 3082 (69 equivalents) of trimethylolpropane,
3312 (23 equivalents) of 2,2,4-trimethylpentanoic acid, 3634 (46 equivalents) ofisobutyric anhydride and 10 parts (0.1 equivalent) of methanesulfonic acid. The
reaction mixture is heated under nitrogen to 115C. The temperature is maintained
between 115C to 150C for 6 hours. The reaction temperature is maintained at
150C for 10 hours while 798 milliliters of distillate is collected. The mixture is
heated to 200C and held for 8 hours while 32 milliliters of distillate is collected.
The total distillate collected is 860 milliliter~. The mixture is cooled to 130C where
350 parts (4.4 equivalents) of isobutyric anhydride are added to the reaction vessel.
The mixture is stirred at 130C for 24 hours. The reaction mixture is vacuum
stripped at 8-10 mm Hg and 120-150C for 8 hours. The acid number after the
stripping was 4.2. The reaction mixture is stripped to 190C and 8-10 mm Hg for
6 hours. The acid number after this stage of stripping is 0.84. The residue is
vacuum stripped for 8 hours at 195C and 10 mm Hg. The acid number after this
stage of stripping is 0.051. The residue of the product has a kinematic viscosity of
14.0 centistokes at 40C and 3.1 centistokes at 100C. The acid number of the
product is 0.05.
Example 3
A reaction vessel is charged with 1139 parts (8.5 moles) of
trimethylolpropane, 1224 parts (8.5 moles) of 2,2,4-trimethylpentanoic acid, and 6
parts of methanesulfonic acid. The mixture is heated under nitrogen to 117C and
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13
the temperature is maintained for 3 hours while a total of 90 milliliters of water is
collected. The mixture is then heated to 150C and the temperature is maintained for
S hours. The total water collected was 153 milliliters. Isobutyric acid (1496 parts,
17 moles) is added to the reaction mixture. The mixture is heated to 120C and aS temperature is maintained between 120C and 125C for 19 hours. The acid number
of the reaction mixture is 41. The reaction mixture is heated to 145C and the
temperature is maintained for 22 hours. The acid number of the reaction mixture is
24. An additional charge is isobutyric acid (200 parts, 2.27 moles) is added to the
reaction mixture. The mixture is heated to 145C and the temperature is maintained
for 22 hours. The reaction mixture is vacuum stripped to 125C and 20-25 mm Hg
for 3 hours. The residue is then subjected to additional vacuum stripping at 150C
and 10 mm Hg for 3 hours. The reaction mixture is then vacuum stripped to 165-
175C and 8-10 mm Hg for 5 hours. The neutralization acid number 2-
phenolphthalein of the residue is 0.29. The residue is vacuum stripped at 175C and
8-10 mm Hg for 6 hours. After this vacuum stripping, the neutralization acid number
is 0.16. The residue is filtered through a 3/4" pad of aluminum oxide. The filtrate
has a acid number of 0.11 and a kinematic viscosity of 14.67 (at 40C) and 3.23 (at
100C).
Example 4
A reaction vessel is charged with 660 parts (5.5 moles) of trimethylolethane,
1122 parts (ll.0 moles) of neopentanoic acid, 869 parts (5.5 moles) of isononanoic
acid, and 3 parts of tetraisopropoxy titanate. The mixture was heated to 220C for
72 hours while water is removed The reaction mixture is stripped for 8 hours at
180-200C. The residue is treated with 200 parts of alumina and filtered throughcloth and diatomaceous earth. The filtrate is the desired product and has a kinematic
viscosity of 23.6 centistokes (at 40C) and 4.0 centistokes (at 100C). The filtrate
has a acid number of 0.08.
Example 5
A reaction vessel is charged with 603 parts (4.5 moles) of trimethylolpropane,
441 parts (3 moles) of 2,2,4-trimethylpentanoic acid, 1065 parts of isopentanoic acid
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14
a mLsture of valeric acid and 2-methylbutyric acid having a weight ratio of (66:34~
and available commercially from Union Carbide), and 4 parts of methanesulfonic
acid. The reaction mixture is heated to 150C and the temperature is maintained for
six hours. Water is collected azeotropically (220 milliliters). The reaction
S temperature is maintained for an additional 31 hours where an additional 10 milliliters
of water is collected. The reaction mixtue is vacuum stripped to 150C and 20 mmHg for 18 hours. The neutralization acid number of the residue is 0.12. The residue
is filtered through alumina and diatomaceous earth. The filtrate is the desired
product.
Example 6
A reaction vessel is charged with 2286 parts (9.0 moles) of dipentaerythritol,
1422 parts (9 moles) of isononanoic acid, 1836 parts (18 moles) of neopentanoic acid,
and 8 parts of methanesulfonic acid. The reaction is heated to 140C and the
temperature is maintained for 18 hours. Water is collected (460 milliliters) by
distillation. An additional charge of isononanoic acid (4266 parts, 27 moles) is added
to the reaction vessel. The reaction is heated to 200C and the temperature is
maintained for 18 hours. The reaction is vacuwm stripped to 200C and 10 mm Hg.
After 15 hours of stripping the acid number was 0.2. The residue was treated with
alumina (800 parts) and the mixture is heated to 110C and the temperature is
maintained for 4 hours. The product is filtered and the filtrate is the desired product.
lhe filtrate has a kinematic viscosity of 720 centistokes at 40C and 30.5 centistokes
(at 100C).
Example 7
A reaction vessel is charged with 166 parts (1.22 moles) of pentaerythr;tol,
151 parts (0.4 moles) of tripentaerythritol, 439 parts (2.7 moles) of isononanoic acid,
391 parts (2.7 moles) of 2,2,4-trimethylpentanoic acid, 214 parts (1.35 moles) of
isobutyric anhydride, and 4 parts of tetra-isopropoxy titanate. The reaction mixture
is heated to 170C and the temperature is maintained for 24 hours. Water is
collected by distillation (130 milliliters). The reaction is vacuum stripped for 3 hours
at 170C and I mm Hg. The product is filtered and the residue has a kinematic
2~9~54
viscosity of 133.8 centistokes (at 40C) and 13.27 centistokes (at 100C). The acid
number of the product is 0.1.
Example 8
A reaction vessel is charged with 192 parts (1.41 moles) of pentaerythritol,
242 parts (0.95 moles) of aipentaerythritol, 1337 parts (8.46 moles) of isononanoic
acid, 406 parts (2.82 moles) of 2,2,4-trimethylpentanoic acid, and 3 parts of
tetraisopropoxy titanate. The reaction mixture is heated to 210C and the temperature
is maintained for 30 hours while water is removed. The reaction mixture is vacuum
stripped to 210C and 10 mm Hg. The residue is treated with alumina and filtered,
The filtrate is the desired product and has a kinematic viscosity of 171,7 centistokes
(at 40C) and 15,4 centistokes (at 100C),
Example 9
A reaction vessel is charged with 374 parts (2,75 moles) of pentaerythritol,
465 parts (1,83 moles) of dipentaerythritol, 3042 parts (19,25 moles) of isononanoic
acid, 217 parts (1,37 moles) of isobutyric anhydride, and 4 parts of methanesulfonic
acid, The reaction mixture is heated to 130C and the temperature is maintained for
24 hours, while 360 milliliters of water is collected, An addidonal charge of
isobutyric anhydride (20 grarns) is added to the reaction mixture at 100C, The
reaction mixture is heated to 190C and blown with nitrogen at 2 standard cubic feet
per hour for 6 hours, The product is vacuum stripped for 24 hours at 200C and 10
mm Hg, After 16 hours of vacuum stripping the acid number is 0,15. After 24
hours of vacuum stripping the acid number is 0.1. The residue is treated with
alumina (300 parts) at 120C, The acid number after alumina treatrnent is 0,05, The
mixture is filtered through a pad of alumina and diatomaceous earth, The filtrate is
the desired product and has a kinematic viscosity of 182 centistokes (at 40C) and
15,6 centistokes (at 100C), The filtrate has a acid number of 0,OS,
The esters (B) preferably contain branched alkyl groups and generally are free
of acetylenic and aromatic unsaturation, The soluble lubricants of this invention also
are preferably free of olefinic unsaturation except that some olefinic unsaturadon may
be present so long as the lubricant is soluble,
2~948~
16
The carboxylic esters (B) are soluble in the fluoline containing hydrocarbons
and, in particular, in the fluorohydrocarbons such as 1,1,1,2-tetrafluoroethane. The
lubricants are soluble over a wide temperature range and, in par~cular, at low
temperatures. The solubility of the lubricants in fluorohydrocarbons such as
1,1,1 ,2-tetrafluoroethane at low temperatures is determined in the following manner.
The lubricant (0.5 gram) is placed in a thick-walled glass vessel equipped with a
removable pressure gauge. The tetrafluoroethane (4.5 grams) is condensed into the
cooled (-40C) glass vessel, and the contents are warmed to the desired temperature
and mixed to determine if the lubricant is soluble in the tetrafluoroethane. If soluble,
the temperature of the mixture is reduced until a separation and/or precipitate is
observed. The results of this solubility test conducted with several examples of the
carboxylic ester lubricants of the present invention are summarized in the following
Table I.
TABLE I
Liquid Containing Solubility
Product of Example C (~pt.!
c -78
2 -31
3 c-78
4 <-40
6 -35
7 -5
8 -24
The liquid compositions may additionally contain (C) at least onc additive
selected frorn the group consisting of an alkyl phosphite, an alkyl phosphonic acid
ester, a nitrogen-containing heterocycle, and a mixture thereof. The phosphite and/or
the alkyl phosphonic acid ester are present in an amount sumcient to provide antiwear
and /or extreme pressure properties to the lubricant and liquid composition. Thephosphite and/or the alkyl phosphonic acid ester are present in an amount to provide
2~94~54
0.001%, or to 0.015 %, or about 0.025 %, to about 1%, or to about 0.5 %, or to about
0.2 % by weight phosphorus to the lubricant. The nitrogen-containing heterocycle is
present in an amount from about 0.001%, or about 0.02%, or about 0.03% up to
about 5%, or to about 2%, or to about 1%, or to about 0.5% by weight of the
lubricant.
The phosphite and/or the allyl phosphonic acid ester provide beneficial
antiwear and extreme pressure properties to the liquid compositions. The phosphite
may be a dialkyl or trialkyl phosphite, preferably a dialkyl phosphite. The alkyl
phosphonic acid ester may be an alkyl phosphonic acid diester, preferably a
dialkylester. The alkyl groups of the phosphite and the phosphonic acid ester
independently contain from 1, or about 3 to about 20, or to about 18, or to about 8
carbon atoms. In one embodiment, the phosphite and the phosphonic acid ester have
alkyl groups independently containing from about 3 to about 6, or to about 5 carbon
atoms. A number of dialkyl phosphites are commercially available, such as lower
dialkyl phosphites, which are preferred. Lower dialkyl phosphites include dimethyl,
diethyl, dipropyl, dibutyl, dipentyl and dihexyl phosphites. Phosphites and their
preparation are known and many phosphites are available commercially. Also mixedalkyl phosphites, made from a mixture of alc~hols, are useful in the present inven-
tion. Examples of mixtures of alcohols include ethyl and butyl alcohol; propyl and
pentyl alcohol; and methyl and pentyl alcohol. A particularly useful phosphite is
dibutyl phosphite.
Alkyl phosphonic acid esters are prepared by means known to those in the art.
For example, alkyl phosphonic acid esters may be prepared by reacting an alkyl
halide with a trialkyl phosphite. Examples of alkyl phosphonic acid esters include
diethyl, butylphosphonate; dibutyl7butylphosphonate; 2-ethylhexyl,2-
ethylhexylphosphonate, etc.
The lubricant may additionally contain a nitrogen-containing heterocycle, such
as dimercaptothiadiazoles, triazoles, amino-mercaptothiadiazoles, imidazoles,
thiazoles, tetrazoles, hydroxyquinolines, oxazolines, imidazolines, thiophenes,
indoles, indazoles, quinolines, benzoxazines, dithiols, oxazoles, oxatriazoles,
2~g~
pyridines, piperazines, triazines, and derivatives of any one or more thereof. In one
embodiment, the nitrogen containing heterocycle is a tnazole or deriva~ve thaeof,
a thiazole or derivative thereof, a mercaptothiazole or derivative ~ereof and a
thiadiazole or derivative thereof, preferably a triazole or derivative thereof. These
additives provide metal deactivating, metal passivating and corrosion controlling
character to the liquid compositions. Examples of useful metal deactivators include
dimercaptothiadiazoles and derivatives thereof, substituted and unsubstituted triazoles
(e.g., benzotriazole, tolyltriazole, octylbenzotriazole, and the like),
mercaptobenzothiazoles, etc. Examples of these compounds are benwtriazole, alkyl-
substituted benwtriawle (e.g., tolyltriazole, ethylbenzotriazole, hexylbenzotriazole,
octylbenzotriazole, etc.), aryl-substituted benzotriazole (e.g., phenol benzotriazoles,
etc.), and alkylaryl- or arylalkyl-substituted benzotriazole and substituted
benzotriazoles where the substituent may be hydroxy, alkoxy, halo (especially
chloro), nitro, carboxy and carboxyalkoxy. Preferably, the triazole is a benzotriazole
or an alkylbenzotriazole in which the alkyl group contains 1 to about 20 carbon
atoms, preferably 1 to about 8 carbon atoms.
The nitrogen containing heterocycle (C) may also be the reaction product of
at least one of the above triazoles, at least one amine and an aldehyde or aldehyde
precursor. The triazole is preferably a benzotriazole. The amine can be one or more
mono- or polyamines. These monoamines and polyamines can be primary amines,
secondary amines or tertiary amines. Examples of polyamines include
polyalkylencpolyamines, and heterocyclic polyamines. Polyalkylenepolyamines
include polyethylenepolyamines, such as diethylenetriamine, triethylenetriamine,tetracthylenepentaamine, etc.
The aldehyde is typically a hydrocarbon-bascd aldehyde, preferably a lower
aliphatic aldehyde. Suitable aldehydes include i~ormaldehyde, benzaldehyde, acetalde-
hyde, the butyraldehydes, hydroxybutyraldehydes and heptanals, as well as aldehyde
precursors which react as aldehydes under the conditions of the reaction such asparaformaldehyde, paraldehyde, formalin and methanal. Formaldehyde and its
2~948~
19
precursors (e.g., paraformaldehyde, ~ioxane) are prefeITed. Mi~ctures of aldehydes
may be used.
An exarnple of a useful triazole derivative is ReomeP 39. This material is a
triazole derivative available commercially from Ciba-Cieigy Corp.
S The liquid compositions of the present invention are characterized as having
improved thermal and chemical stability over a wide temperature range. The liquid
compositions with (C) phosphites, alkylphosphonates, or nitrogen-containing
heterocycles have improved antiwear and corrosion stability properties. The liquid
compositions have beneficial viscosity properties. Preferably the liquid compositions
have a viscosity of 5-400 centistokes (cSt) measured at 40C.
The liquid composition may contain one carboxylic ester reaction product or
in another embodiment, the liquid compositions may contain a blend of two or more
carboxylic ester reaction products. A liquid composition of a desired viscosity may
be prepared by blending a higher viscosity carboxylic ester with a lower viscosity
carboxylic ester. Other additives, if soluble in the liquid, known to be useful for
improving the properties of halogen-containing hydrocarbon refrigerants can be
included in the liquid compositions of the present invention to improve the charac-
teristics of the liquid as a refrigerant. However, hydrocarbon oils such as mineral oil
generally are not included in and are most often excluded from the liquid
compositions of the invention, particularly when the fluorine-containing hydrocarbon
contains no other halogens. Hydrocarbon lubricants, however, may be present if the
liquid compositions are used to retrofit a compressor system which had previously
used a hydrocarbon lubricant.
Other additives may be included in the liquid compositions of the present
invention to enhance the performance of the liquids include extreme-pressure andanti-wear agents, oxidation and thermal-stability improvers, corrosion-inhibitors,
viscosity-index improvers, pour point and/or floc point depressants, detergents,dispersants, anti-foaming agents, viscosity adjusters, metal deactivators, etc. As
noted above, these supplementary additives must be soluble in the liquid compositions
of the invention. Included among the materials which may be used as
2~9~8~
extreme-pressure and anti-wear agents are phosphates, phos~hate esters,
thiophosphates such as zinc diorganodithiophosphates, chlorinated wa~es, sulfurized
fats and olefins, organic lead compounds, fatty acids, molybdenum complexes,
borates, halogen-substituted phosphorous compounds, sulfurized Diels Alder adducts9
organic sulfides, metal salts of organic acids, etc. Sterically hindered phenols,
aromatic amines, dithiophosphates, sulfides and metal salts of dithioacids are useful
examples of oxidation and thermal stability improvers. Compounds useful as
corrosion-inhibitors include organic acids, organic amines, organic phosphates,
organic alcohols, metal sulfonates, etc. VI improvers include polyolefins such as
polyesterbutene, polymethacrylate, polyalkyl styrenes, etc. Pour point and floc point
depressants include polymethacrylates, ethylene- vinyl acetate copolymers, succinamic
acid-olefin copolymers, ethylene-alpha olefin copolymers, etc. Detergents include
sulfonates, long-chain alkyl-substituted aromatic sulfonic acids, phenylates, metal salts
of alkyl phenols, alkyl phenol-aldehyde condensation products, metal salts of
substituted salicylates, etc. Silicone polymers are a well known type of anti- foam
agent. Viscosity adjusters are exemplified by polyisobutylene, polymethacrylates,
polyalkyl styrenes, naphthenic oils, alkyl benzene oils, polyesters, polyvinyl chloride,
polyphosphates, etc.
The following examples (TABLE 1) relate to formulations which are useful
as organic lubricant (B) in the present invention.
x ~ ~9485~
~ o o o
U' /,
o~ o o
oo
o o
o~
:~ ~ o o
~ ~ ~ ~ o o
o ~ 8
æ
O
.~ ~d
~.VI
V~ O
~9~5~
22
The liquid compositions of the present invention are particularly useful as
refrigerants in various refrigeration sys~ems which are compression-type systems such
as refrigerators, freezers, and air-conditioners including automotive, home,
commercial, and industrial air-conditioners. The following examples are illustrative
of the liquid compositions of the present invention.
Parts by Wt.
Example A
1,1,1,2-tetrafluoroethane (HCFC-134a) 90
Product of Example 2 10
Example B
1,1,2,2-tetrafluoroethane 60
Product of Example 4 40
Examl?le C
HCFC-134a 45
Product of Example 6 55
~ple D
HCFC 134a 80
Product of Example 1 20
l~xample E
HCFC-134a 85
Product of Example Il 15
Table 2 contains further examples of the liquid compositions of the present
invention.
2~9~85~
Table 2
F E H
HFC-134a 80 85 60 45 85
Lubricant of
S Example:
III 20
V 15 55
II 40 15
While the invention has been explained in relation to its preferred
embodiments, it is to be understood that various modifications thereof will become
apparent to those skilled in the art upon reading the specification. Therefore, it is to
be understood that the invention disclosed herein is intended to cover such
modifications as fall within the scope of the appended claims.
