U.S. patent application number 10/207178 was filed with the patent office on 2003-02-27 for refrigerant lubrificant composition comprising a foam-inducing additive.
This patent application is currently assigned to Imperial Chemical Industries Plc. Invention is credited to Boyde, Stephen.
Application Number | 20030040445 10/207178 |
Document ID | / |
Family ID | 9884526 |
Filed Date | 2003-02-27 |
United States Patent
Application |
20030040445 |
Kind Code |
A1 |
Boyde, Stephen |
February 27, 2003 |
Refrigerant lubrificant composition comprising a foam-inducing
additive
Abstract
A lubricant composition has a synthetic lubricant base oil,
preferably a polyol ester, and a polyether foam-inducing additive.
The composition is suitable for use in a refrigerant system,
particularly with HFC refrigerant gases. The foam-inducing additive
is an alternative to known silicon-containing foam-inducing
additives, which are not suitable for all refrigerant systems.
Inventors: |
Boyde, Stephen; (Cleveland,
GB) |
Correspondence
Address: |
Pillsbury Whinthrop LLP
Intellectual Property Group
1600 Tyson's Boulevard
McLean
VA
22101
US
|
Assignee: |
Imperial Chemical Industries
Plc
London
GB
|
Family ID: |
9884526 |
Appl. No.: |
10/207178 |
Filed: |
July 30, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10207178 |
Jul 30, 2002 |
|
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PCT/GB01/00255 |
Jan 24, 2001 |
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Current U.S.
Class: |
508/582 |
Current CPC
Class: |
C10N 2040/36 20130101;
C10M 171/008 20130101; C10M 2211/06 20130101; C10M 2209/103
20130101; C10M 2203/06 20130101; C10M 2209/04 20130101; C10M
2209/104 20130101; C10M 2209/1033 20130101; C10M 2211/022 20130101;
C10N 2040/44 20200501; C10N 2040/50 20200501; C10N 2040/30
20130101; C10M 2207/2835 20130101; C10N 2040/32 20130101; C10M
169/041 20130101; C10N 2040/34 20130101; C10M 107/34 20130101; C10M
2209/107 20130101; C10M 2213/04 20130101; C10M 2203/065 20130101;
C10M 105/06 20130101; C10M 2207/283 20130101; C10M 2209/106
20130101; C10N 2040/38 20200501; C10M 105/38 20130101; C10M
2209/1065 20130101; C10N 2040/00 20130101; C10M 2209/1045 20130101;
C10M 2209/1095 20130101; C10M 2209/1055 20130101; C10M 2213/06
20130101; C10N 2040/40 20200501; C10M 147/04 20130101; C10M
2209/1075 20130101; C10M 2209/1085 20130101; C10M 2207/286
20130101; C10M 2207/281 20130101; C10M 2209/06 20130101; C10M
2207/282 20130101; C10N 2040/42 20200501; C10M 2209/062 20130101;
C10M 2213/00 20130101; C10M 2209/105 20130101 |
Class at
Publication: |
508/582 |
International
Class: |
C10M 101/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2000 |
GB |
0001981.0 |
Claims
1 A lubricant composition comprising; a) a synthetic lubricant base
oil; and b) a foam-inducing additive, which comprises a polyether
having the formula X-O--(RO).sub.n--Y wherein--O--(RO).sub.n-- is a
polyether backbone R is a partially or fully halogenated alkyl
group having 1 to 10 carbon atoms and wherein adjacent R groups may
be the same or different n is in the range 1 to 1000 and x and y
are end groups.
2 A lubricant composition according to claim 1 wherein R is a fully
halogenated alkyl group having 1 to 7 carbon atoms.
3. A lubricant composition according to claim 1 or claim 2 wherein
the halogen is fluorine.
4 A lubricant composition according to any one of claims 1 to 3
wherein n is in the range 1 to 100.
5 A lubricant composition according to any one of claims 1 to 4
wherein at least one of the end groups X and Y comprise at least
one functionalised group.
6. A lubricant composition according to claim 5 wherein the at
least one functionalised group is positioned at the extremity of
the end group away from the polyether backbone.
7. A lubricant composition according to claim 5 or claim 6 wherein
the at least one functionalised group includes haloalkyl
groups.
8. A lubricant composition according to any one of claims 1 to 7
wherein the foam-inducing additive is present at a level of between
0.0001 to 0.1% by weight of the lubricant composition.
9. A lubricant composition according to any one of claims 1 to 8
wherein the synthetic lubricant base oil is chosen from
alkylbenzenes, polyvinyl ethers, polyalkylene glycols and
esters.
10. A lubricant composition according to claim 9 wherein the
synthetic lubricant base oil is an ester which is a derivative of a
polyol.
11. Use of a lubricant composition in a refrigeration system
wherein the lubricant composition comprises a) a synthetic
lubricant base oil; and b) a foam-inducing additive, which
comprises a polyether having the formula X-O--(RO)n--Y
wherein--O--(RO).sub.n-- is a polyether backbone R is a partially
or fully halogenated alkyl group having 1 to 10 carbon atoms and
wherein adjacent R groups may be the same or different n is in the
range 1 to 1000 and X and Y are end groups.
Description
[0001] This invention relates to a lubricant composition and its
use in refrigeration systems.
[0002] It is known that excessive foaming in refrigeration systems
is undesirable. It reduces the lubricant composition's
effectiveness in cooling the motor windings and removing heat from
the compressor. Also too much foam can cause too much lubricant
composition to pass through the system pump and enter the
low-pressure side of the refrigeration system. However, a moderate
amount of foaming can be beneficial, particularly for suppression
of noise within the refrigeration system compressor. Section 7.20
of the 1998 ASHRAE Refrigeration Handbook states that "a foamy
layer on top of the lubricant level dampens the noise created by
the moving parts of the compressor". There are other benefits of
foam creation; for example control of vapour release rate as
disclosed in WO/9512649 and promotion of enhanced oil return as
disclosed in U.S. Pat. No. 4,829,786.
[0003] Historically, mineral oils were used in lubricant
compositions for chlorofluorocarbon (CFC) and
hydrochlorofluorocarbon (HCFC) refrigerant gases. These lubricant
composition/CFC/HCFC mixtures demonstrated a tendency to foam. In
some cases in which foaming is undesirable or excessive it was
found to be necessary to control foam production. In other
instances, where foaming is advantageous, it was found necessary to
promote foaming. For example, U.S. Pat. No. 3,792,755 discloses a
method of attenuating the noise produced by an operating hermetic
compressor unit which has a means for agitating the lubricant
composition during operation, which lubricant composition contains
a foaming agent, which is an organosiloxane. The foaming agent
assists in generating and sustaining a froth or foam of fine
bubbles which acts to absorb and thus attenuate the noise produced
by the compressor unit during operation CFCs disclosed in U.S. Pat.
No. 3,792,755 include trichloroethylene, dichlorodifluoromethane
(R-12) and monochlorodifluoromethane (R-22).
[0004] In recent years, legislation has dictated a move away from
such traditional refrigerant gases to alternatives having lower- or
zero-ozone depletion potential, such as hydrofluorocarbon gases
(HFC). This change in refrigerant gas has necessitated a change in
lubricant composition away from mineral oils, which are not
compatible with these new HFC gases More polar, HFC-compatible,
synthetic lubricant compositions are used Examples of suitable base
fluids for such synthetic lubricant compositions are polyalkylene
glycols, polyol esters, polyvinyl ethers and alkylbenzenes.
[0005] It has been found that mixtures of HFC refrigerant gases and
such synthetic lubricant compositions tend to show a much lower
inherent foaming tendency than CFC mixtures with mineral oil based
lubricant compositions; for example see Chapter 5 of "Foaming
Characteristics of Refrigerant/Lubricant Mixtures", reference
number DOE/CE/23810-88a which reported work supported by the US
Department of Energy and was prepared for The Air-Conditioning and
Refrigeration Technology Institute in March 1998. Consequently,
when foam generation is an advantage, there is a need to generate a
froth or foam of fine bubbles in the lubricant composition. The
generation of such foam can be achieved by the addition of a
foaming additive to the lubricant composition.
[0006] Known foaming additives are silicon based, for example
organosiloxanes or silicones. WO95/12649 discloses a lubricant
composition comprising a synthetic polyol ester lubricant and a
foam density-increasing additive for use in a refrigerator system
with at least one compressor and a halocarbon refrigerant gas,
preferably an HFC. The foam density-increasing additive is
preferably a siloxane but may also be a halogenated aliphatic
polymeric ester (for example Fluorad FC430 available from 3M) and
is found to both increase the foam density and control vapour
evolution from the compressor.
[0007] EP 0590238 A1 discloses a compressor for compressing an HFC
refrigerant which is characterised by the presence of a lubricant
composition consisting of a pentaerythritol ester and a siloxane
foaming additive wherein an oil foam layer is created during
compressor operation to reduce compressor noise.
[0008] JP10088173 A2 discloses lubricant compositions for
refrigeration compressors for noise reduction comprising HFC
refrigerants, ester oil lubricants with at least 2 ester bonds, a
hydrolytic stabiliser, an antioxidant and 0.001-0.01 wt. % of
silicone oils.
[0009] However, these silicon-containing foaming additives may not
be suitable for all refrigerant systems as they are only partially
miscible with the base oil of the lubricant composition. This may
lead to separation of the silicon-containing additives in cold
parts of the refrigeration system The loss of the
silicone-containing additives may also cause loss of foaming due to
additive depletion, fouling of heat exchange surfaces and valve
blockage. Furthermore silicones present on metal surfaces prevent
painting of such surfaces.
[0010] Hence alternative foaming additives are being sought.
[0011] Accordingly, in a first aspect, the present invention
provides a lubricant composition comprising;
[0012] a) a synthetic lubricant base oil; and
[0013] b) a foam-inducing additive, which comprises a polyether
having the formula
X-O--(RO).sub.n--Y
[0014] wherein--O--(RO).sub.n-- is a polyether backbone
[0015] R is a partially or fully halogenated alkyl group having 1
to 10 carbon atoms and wherein adjacent R groups may be the same or
different
[0016] n is in the range 1 to 1000 and
[0017] X and Y are end groups.
[0018] By partially halogenated, we mean that at least one hydrogen
atom of the alkyl group has been replaced by a halogen atom.
Preferably at least one hydrogen atom in each of the carbon atoms
of the alkyl group has been replaced by a halogen atom, more
preferably all of the hydrogen atoms of the alkyl group have been
replaced by halogen atoms so that R is a fully halogenated alkyl
group. Preferably the halogen atom is a fluorine atom. Especially
preferred is when fluorine atoms have replaced all of the hydrogen
atoms of the alkyl group.
[0019] The alkyl group, R, may be branched or straight chained and
it may be saturated or unsaturated. R preferably has 1 to 7 carbon
atoms, more preferably 1 to 4 carbon atoms. Examples of preferred R
include --CF.sub.2-- --CF.sub.2CF.sub.2--, --CF(CF.sub.3)--,
--CF(CF.sub.3)CF.sub.2--, --CF.sub.2CF.sub.2CF.sub.2-- and
--CF.sub.2CF.sub.2CF.sub.2CF.sub.2--. R can be chosen such that the
polyether is a block, random or graft copolymer or a
homopolymer.
[0020] n is preferably in the range from 1 to 100, more preferably
from 1 to 50. n may be the same or different for the R groups.
[0021] An example of a preferred embodiment is
X-O--(R.sup.1O).sub.n1--(R.sup.2O).sub.n2--Y
[0022] where R.sup.1 and R.sup.2 are as defined for R but R.sup.1
is different to R.sup.2. n1 and n2 may be the same or
different.
[0023] The polyether backbone has two end groups, X and Y.
Preferably at least one of the end groups X and Y comprises at
least one functionalised group. Types of functionalised groups
include hydroxyl, ester, ethoxylated hydroxyl, ethoxylated ester,
both organic and inorganic, amine, cyano, and amide The or each
functionalised group may be positioned on the end group so as to be
directly linked to the polyether backbone; or it may be positioned
at the extremity of the end group away from the polyether backbone;
or it may be positioned within the backbone of the end group.
Preferably the functionalised group is positioned at the extremity
of the end group away from the polyether backbone Other groups that
may be present within the or each end group include alkyl and
haloalkyl, in particular fluoralkyl. Preferably the end group is
such that it confers solubility of the foam-inducing additive in
the synthetic lubricant base oil, Examples of end groups, which
comprise a functionalised group, are --CF.sub.2COOCH.sub.3,
--CF.sub.2CH.sub.2OH, --CF.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.nH
and --CF.sub.2CH.sub.2OCH.s- ub.2CH(OH)CH.sub.2OH.
[0024] The foam-inducing additive preferably has a molecular weight
between 100 and 10000 atomic units, more preferably between 200 and
5000 atomic units. It is present at a level of between 0.0001 to
1.0% by weight in the lubricant composition, preferably at a level
of between 0.0001 to 0.05%
[0025] The synthetic lubricant base oil is selected such that the
lubricant composition is compatible with HFC refrigerant gases.
Preferably, it is selected from alkylbenzenes, polyvinyl ethers,
polyalkylene glycols and esters. Preferably the synthetic lubricant
base oil is an ester; more preferably an ester which is a
derivative of a polyol, preferably an aliphatic hydrocarbon-based
polyol, having from 2 to 6 hydroxyl groups and, preferably, from 3
to 12 carbon atoms. Suitable polyois include neopentyl glycol,
pentaerythritol, trimethylolpropane, ditrimethylolpropane and
dipentaerythritol. The ester is derived from the reaction of such a
polyol with one or more linear or branched, saturated or
unsaturated monocarboxylic acids having from 3 to 12 carbon atoms
and optionally one or more linear or branched, saturated or
unsaturated polycarboxylic acids having from 4 to 54 carbon atoms.
Preferably the polycarboxylic acids, if present, have 2 or 3
carboxyl groups. All of the above acids may be replaced by their
esterifiable derivatives, for example anhydrides.
[0026] Examples of suitable lubricant compositions include the
EMKARATE RL range of refrigeration lubricants available from
Uniqema, a business of Imperial Chemical Industries plc. The
synthetic lubricant base oils for these lubricant compositions are
derived from pentaerythritol or oligomers thereof and/or neopentyl
glycol reacted with linear and/or branched acids (or their
esterifiable derivatives) having from 5 to 10 carbon atoms.
[0027] The synthetic lubricant base oil has a viscosity at
40.degree. C. from 2 to 500 cSt.
[0028] The lubricant composition has a viscosity at 40.degree. C.
from 2 to 500 cSt. The lubricant composition may further comprise
other foaming additives, for example organosiloxanes or silicones.
If present, such other foaming additives are at a level of between
0.0001 to 1.0% by weight in the lubricant composition, preferably
at a level of between 0.0001 to 0.1%, more preferably at a level
between 0.0001 to 0.05%. The lubricant composition may also
comprise other functional lubricant additives. Suitable additives
include antioxidants, antiwear additives, extreme pressure agents,
acid scavengers, stabilisers, surfactants, viscosity index
improvers, corrosion inhibitors, metal deactivators or passivators,
lubricity improvers or oiliness agents and friction modifiers
[0029] In a second aspect, the present invention provides for use
of a lubricant composition in a refrigeration system wherein the
lubricant composition comprises
[0030] a) a synthetic lubricant base oil; and
[0031] b) a foam-inducing additive, which comprises a polyether
having the formula
X-O--(RO).sub.n--Y
[0032] wherein--O--(RO).sub.n-- is a polyether backbone
[0033] R is a partially or fully halogenated alkyl group having 1
to 10 carbon atoms and wherein adjacent R groups may be the same or
different
[0034] n is in the range 1 to 1000 and
[0035] X and Y are end groups.
[0036] The refrigerant in the refrigerant system suitably comprises
a hydrochlorofluorocarbon (HCFC), an HFC or a blend of refrigerants
containing at least one HFC, HCFC or both. Preferably the
refrigerant does not contain any chlorine atoms. Suitable HFC gases
include R134a (1,1,1,2-tetrafluoroethane), R-32 (difluoromethane).
R-125 (1,1,1,2,2-pentafluoroethane), R-152a (1,1-difluoroethane)
and R-143a (1,1,1-trifluoroethane). There may be other components
in the refrigerant blend, for example hydrocarbons, preferably with
1 to 6 carbon atoms, fluorinated hydrocarbons and other
refrigerants, for example carbon dioxide or ammonia.
[0037] The present invention is further illustrated with reference
to the following non-limiting examples.
EXAMPLE 1
[0038] The foaming tendency and foam stability of 200 mls of a
lubricant composition comprising EMKARATE RL 22H ex ICI and various
levels of foam-inducing additive, Fomblin HC-OH ex Ausimont
(HOCH.sub.2CF.sub.2O--(-
CF.sub.2CF.sub.2O).sub.p--(CF.sub.2O).sub.q--CF.sub.2CH.sub.2OH),
were measured at room temperature (24.5.degree. C.) The foaming
tendency of the lubricant composition was determined using the
standard test method ASTM D-892-97, Standard Test Method for
Foaming Characteristics of Lubricating Oils. The test determines
the foam tendency in terms of the volume of foam produced by
bubbling air through 200 mls of the lubricant composition. The foam
stability is the time taken in seconds for the foam to
disappear.
[0039] The results are shown in Table 1.
EXAMPLE 2
[0040] Example 1 was repeated except that R134a was bubbled through
the lubricant composition instead of air. The results are shown in
Table 2.
EXAMPLE 3
[0041] Example 1 was repeated except the Fomblin HC-OH was replaced
by Fluorolink E10
(H(OCH.sub.2CH.sub.2).sub.nOCH.sub.2CF.sub.2O--(CF.sub.2CF-
.sub.2O).sub.p--(CF.sub.2O).sub.q--CF.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).su-
b.nH) ex Ausimont. The results are shown in Table 3.
1TABLE 1 Concentration of Foam Tendency Foam Stability Fomblin
HC--OH (ppm) (ml) (seconds) 0 0 0 20 20 0 50 380 135 100 380 219
250 400 206 500 370 220
[0042]
2TABLE 2 Concentration of Foam Tendency Foam Stability Fomblin
HC--OH (ppm) (ml) (seconds) 0 0 0 20 0 0 50 40 35 100 30 27 250 20
10 500 30 19
[0043]
3TABLE 3 Concentration of Fluorolink E10 (ppm) Foam Tendency (ml)
Foam Stability (seconds) 0 0 0 250 390 194
EXAMPLE 4
[0044] The foaming tendency and foam stability of 200 mls of a
lubricant osition comprising various EMKARATE RL grades ex ICI and
250 ppm -inducing additive Fomblin HC-OH were measured at room
temperature (24.5.degree. C.) by bubbling through both air and
R134a. The results are shown in Table 4.
4TABLE 4 Foam Foam Foam Foam Stability Stability EMKARATE Tendency
in Tendency in in Air in R134a RL Grade Air (ml) R134a (ml)
(seconds) (seconds) 32H 480 50 294 58 15H 230 50 112 21 7H 50 30 21
12
EXAMPLE 5
[0045] The foaming tendency and foam stability of 200 mls of a
lubricant composition comprising EMKARATE RL 22H ex ICI and various
foam-inducing additives were measured at room temperature
(24.5.degree. C.). The results are shown in Table 5.
5TABLE 5 Foam Tendency in Foam Stability in Foam Inducing Additive
(ppm) Air (ml) Air (seconds) Fomblin HC--OH (250 ppm) 470 237
Fluorolink E10 (250 ppm) 390 194 Fluorad FC430 (250 ppm) 0 0
(Comparative) FS1265 (250 ppm) (Comparative) 360 222 Fomblin Y Lvac
(250 ppm) 0 0 (Comparative) PDMS 1 (500 ppm) (Comparative) 5 13
PDMS 2 (500 ppm) (Comparative) 5 30 FS1265 is trifluoromethyl
siloxane ex Dow. Fomblin Y Lvac is a perfluoroalkylether of
molecular weight about 2400 ex Ausimont. PDMS 1 is Silicone Fluid
SWS-101 50 ex Akrochem of viscosity 50 cSt. PDMS 2 is Silicone
Fluid SWS-101 350 ex Akrochem of viscosity 350 cSt. Fluorad FC430
is a fluorinated surfactant ex 3M.
[0046] The results are indicative of superior foam tendency and
stability of lubricant compositions of the present invention.
EXAMPLE 6
[0047] Example 1 was repeated using 250 ppm Fomblin HC-OH and the
addition of 120 ppm of 50 cSt Silicone Fluid SWS-101 50 ex
Akrochem. The results are shown in Table 6.
6TABLE 6 Foam Tendency in Foam Stability in Foam Inducing Additive
(ppm) Air (ml) Air (seconds) Fomblin HC--OH (250 ppm) and 350 178
Silicone (120 ppm) Silicone (120 ppm) only-Comparative 150 78
* * * * *