U.S. patent application number 12/817316 was filed with the patent office on 2010-10-07 for process for lubricating a refrigerator containing sliding parts made of an engineering plastic material.
This patent application is currently assigned to Idemitsu Kosan Co., Ltd.. Invention is credited to Masato KANEKO.
Application Number | 20100252772 12/817316 |
Document ID | / |
Family ID | 37808737 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100252772 |
Kind Code |
A1 |
KANEKO; Masato |
October 7, 2010 |
PROCESS FOR LUBRICATING A REFRIGERATOR CONTAINING SLIDING PARTS
MADE OF AN ENGINEERING PLASTIC MATERIAL
Abstract
A process to lubricate a refrigerator preferably having a
sliding portion which is made of an engineering plastic material,
or provided thereon with an organic coating film or an inorganic
coating film is provided. The process includes contacting sliding
parts of the refrigerator with a refrigerating machine oil
composition having a base oil containing a polyvinyl ether and/or a
polyoxyalkylene glycol derivative as a main component and having a
kinematic viscosity of 1 to 8 mm.sup.2/s as measured at 40.degree.
C. The refrigerating machine oil composition has a low viscosity,
an improved energy saving performance, a good sealability and an
excellent compatibility with a refrigerant and, therefore, the
process can be suitably used in various refrigerating application
fields, in particular, in closed-system refrigerators.
Inventors: |
KANEKO; Masato; (Chiba,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Idemitsu Kosan Co., Ltd.
Chiyoda-ku
JP
|
Family ID: |
37808737 |
Appl. No.: |
12/817316 |
Filed: |
June 17, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11913108 |
Oct 30, 2007 |
|
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PCT/JP2006/316864 |
Aug 28, 2006 |
|
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12817316 |
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Current U.S.
Class: |
252/68 |
Current CPC
Class: |
C10N 2050/14 20200501;
C10N 2020/04 20130101; C09K 5/045 20130101; C09K 5/041 20130101;
C10M 2209/043 20130101; C10M 2207/042 20130101; C10M 2209/1055
20130101; C10N 2020/105 20200501; C10N 2030/10 20130101; C10N
2020/106 20200501; C10N 2020/103 20200501; C10M 2223/041 20130101;
C10M 2207/126 20130101; C10N 2040/30 20130101; Y02P 20/10 20151101;
C10M 2229/025 20130101; C10M 107/34 20130101; C10N 2080/00
20130101; C10M 169/04 20130101; C10N 2020/02 20130101; C10M
2209/1033 20130101; C10N 2030/06 20130101; C10N 2020/101 20200501;
C10N 2030/02 20130101; C10M 2203/0206 20130101; C10M 2229/02
20130101; C10M 107/24 20130101; Y02P 20/124 20151101; C10M 171/008
20130101; C09K 5/042 20130101; C10M 2223/047 20130101; C10M
2209/1055 20130101; C10M 2209/1085 20130101 |
Class at
Publication: |
252/68 |
International
Class: |
C09K 5/04 20060101
C09K005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2005 |
JP |
2005-252642 |
Claims
1. A process for lubricating a refrigerator, comprising: contacting
moving parts of the refrigerator with a refrigerating machine oil,
comprising: a base oil having a polyvinyl ether, a polyoxyalkylene
glycol derivative or a mixture of a polyvinyl ether and a
polyoxyalkylene glycol derivative as a main component; wherein a
kinematic viscosity of the refrigerating machine oil is 1 to 8
mm.sup.2/s as measured at 40.degree. C., and the refrigerator
comprises a sliding portion which is made of an engineering plastic
material, or provided thereon with an organic coating film or an
inorganic coating film.
2. The process for lubricating a refrigerator according to claim 1,
wherein the organic coating film is a polytetrafluoroethylene
coating film, a polyimide coating film or a polyamide imide coating
film.
3. The process for lubricating a refrigerator according to claim 1,
wherein the inorganic coating film is a graphite film, a
diamond-like carbon film, a tin film, a chromium film, a nickel
film or a molybdenum film.
4. The process for lubricating a refrigerator according to claim 1,
wherein the refrigerator comprises a refrigerant selected from the
group consisting of a hydrocarbon-based refrigerant, a carbon
dioxide-based refrigerant, a hydrofluorocarbon-based refrigerant
and an ammonia-based refrigerant.
5. The process for lubricating a refrigerator according to claim 4,
wherein the refrigerant is a hydrocarbon based refrigerant.
6. The process for lubricating a refrigerator according to claim 1,
wherein the refrigerator is employed in a system selected from the
group consisting of hot water supply systems, refrigerating and
heating systems for air conditioners for automobiles, gas heat
pumps, general-purpose air conditioning equipments, refrigerators,
automatic vending machines and showcases.
7. The process for lubricating a refrigerator according to claim 6,
wherein a water content of the system is 60 ppm by mass or less and
a residual air content of the system is 8 kPa or less.
8. The process for lubricating a refrigerator according to claim 1,
wherein a molecular weight of the base oil of the refrigerating
machine oil composition is from 100 to 600.
9. The process for lubricating a refrigerator according to claim 1,
wherein a flash point of the base oil of the refrigerating machine
oil composition is 100.degree. C. or higher.
10. The process for lubricating a refrigerator according to claim
1, wherein the polyvinyl ether is a compound having a repeating
unit represented by the general formula (I): ##STR00003## wherein
R.sup.1, R.sup.2 and R.sup.3 are respectively a hydrogen atom or a
hydrocarbon group having 1 to 8 carbon atoms, and may be the same
or different; R.sup.4 is a divalent hydrocarbon group having 1 to
10 carbon atoms; R.sup.5 is a hydrocarbon group having 1 to 20
carbon atoms; k is a number of 0 to 10 on average; R.sup.1 to
R.sup.5 in one repeating unit may be respectively the same as or
different from those in the other repeating units; and when k is 2
or more, a plurality of the R.sup.4O groups may be the same or
different.
11. The process for lubricating a refrigerator according to claim
1, wherein the polyoxyalkylene glycol derivative is a compound
represented by the general formula (II):
R.sup.6--[(OR.sup.7).sub.m--OR.sup.8].sub.n (II) wherein R.sup.6 is
a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an
acyl group having 2 to 10 carbon atoms or an aliphatic hydrocarbon
group having 1 to 10 carbon atoms which contain 2 to 6 bonding
sites; R.sup.7 is an alkylene group having 2 to 4 carbon atoms;
R.sup.8 is a hydrogen atom, an alkyl group having 1 to 10 carbon
atoms or an acyl group having 2 to 10 carbon atoms; n is an integer
of 1 to 6; and m is a number of more than 2 but not more than 20 on
average.
12. The process for lubricating a refrigerator according to claim
1, wherein the refrigerating oil composition further comprises at
least one additive selected from the group consisting of an extreme
pressure agent, an oiliness agent, an antioxidant, an acid
scavenger and a defoaming agent.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of prior U.S.
patent application Ser. No. 11/913,108, filed Oct. 30, 2007, the
disclosure of which is incorporated herein by reference in its
entirety. The parent application is the national stage of
PCT/JP06/316864, filed Aug. 28, 2006, the disclosure of which is
incorporated herein by reference in its entirety. The parent
application claims priority to Japanese Application No. 2005 252642
filed Aug. 31, 2005, the disclosure of which is incorporated herein
by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to refrigerating machine oil
compositions, and more particularly to refrigerating machine oil
compositions having a low viscosity, an improved energy saving
performance, a good sealability and an excellent compatibility with
a refrigerant which are suitably used in various refrigerating
application fields, in particular, closed-system refrigerators.
[0004] 2. Description of Related Arts
[0005] In general, compression-type refrigerators are constituted
from at least a compressor, a condenser, an expansion mechanism
(such as expansion valve), and an evaporator and/or a dryer, and
have such a structure in which a mixed liquid composed of a
refrigerant and a lubricant (refrigerating machine oil) is
circulated through the closed system. In the compression-type
refrigerators, in general, since an inside of the compressor is
kept at a high temperature whereas an inside of the cooler is kept
at a low temperature although these conditions vary depending upon
kinds of refrigerators, it is required that the mixed liquid is
circulated through the system without undergoing a phase separation
thereof into the refrigerant and the lubricant over a wide
temperature range of from the low temperature to the high
temperature. The refrigerant and the lubricant in the mixed liquid
generally have phase separation ranges on high-temperature and
low-temperature sides, respectively. A maximum temperature in the
low-temperature side phase separation range is preferably
-10.degree. C. or lower and more preferably -20.degree. C. or lower
whereas a minimum temperature in the high-temperature side phase
separation range is preferably 30.degree. C. or higher and more
preferably 40.degree. C. or higher. If the mixed liquid undergoes
the phase separation during operation of the refrigerators, the
life or operation efficiency of these apparatuses tends to be
considerably adversely affected. For example, if the mixed liquid
suffers from phase separation into the refrigerant and the
lubricant in the compressor, poor lubrication occurs at a movable
part thereof, resulting in defects such as seizing and, therefore,
remarkably shortened life of the apparatuses. Whereas, if the phase
separation occurs in the evaporator, a heat exchange efficiency of
the apparatuses tends to be deteriorated owing to a high-viscous
lubricant being present therein
[0006] Hitherto, as the refrigerant for refrigerators, there have
been mainly used chlorofluorocarbon (CFC), hydrochlorofluorocarbon
(HCFC), etc. However, these compounds contain chlorine causing
environmental problems. For this reason, there have been presently
made studies for developing alternate refrigerants containing no
chlorine such as hydrofluorocarbon (HFC). However, HFC has been
reported to have adverse influence on global warming. Under these
circumstances, there have been noticed so-called natural
refrigerants suitable for environmental protection such as
hydrocarbons, ammonia and carbon dioxide.
[0007] In addition, since the lubricant for refrigerators are used
in order to lubricate movable parts thereof, it is also important
that the lubricant has a good lubricating performance. In
particular, since an inside of the compressor is likely to be kept
at a high temperature, it is important that the lubricant has a
viscosity capable of retaining an oil film required for a good
lubrication. Although a necessary viscosity of the lubricant varies
depending upon kinds of the compressor and use conditions thereof,
the lubricant before mixing with the refrigerant preferably has a
viscosity (kinematic viscosity) of 10 to 200 mm.sup.2/s as measured
at 40.degree. C. It has been conventionally reported that if the
viscosity of the lubricant is lower than the above specified range,
a thickness of an oil film formed tends to be reduced, resulting in
poor lubrication, whereas if the viscosity of the lubricant is
higher than the above specified range, a heat exchange efficiency
of the refrigerators tends to be lowered.
[0008] For example, there is disclosed a lubricant composition for
vapor compression-type refrigerators using carbon dioxide as a
refrigerant which comprises a lubricant base oil having a 10%
distillation point of 400.degree. C. or higher and a 80%
distillation point of 600.degree. C. or lower as measured by a gas
chromatograph distillation method, a kinematic viscosity of 2 to 30
mm.sup.2/s as measured at 100.degree. C., and a viscosity index of
100 or more (e.g., refer to Japanese Patent Application Laid-open
No. 294886/2001).
[0009] In Examples of the above Japanese Patent Application, it is
described that the kinematic viscosity of the base oil used in the
lubricant composition is in the range of from 17 to 70 mm.sup.2/s
as measured at 40.degree. C.
[0010] The refrigerators using a refrigerating machine oil having
such a high viscosity tend to inevitably suffer from a large energy
consumption. Therefore, for the purpose of saving energy for the
refrigerators, studies have been made to reduce a viscosity of the
refrigerating machine oil and improve frictional properties upon
the lubrication.
[0011] For example, in refrigerators for cold storage, an energy
saving performance thereof has been improved by reducing a
viscosity of the refrigerating machine oil used therein to VG32,
22, 15 and 10, respectively. However, when the viscosity of the
refrigerating machine oil is further reduced, there tends to arise
such a problem that a sealability and a lubricating property
thereof are deteriorated.
SUMMARY OF THE INVENTION
[0012] The present invention has been made in view of the above
conventional problems. An object of the present invention is to
provide a refrigerating machine oil composition having a low
viscosity, an improved energy-saving performance, a good
sealability and an excellent compatibility with a refrigerant which
are suitably used in various refrigerating application fields, in
particular, closed-system refrigerators.
[0013] As a result of intensive and extensive researches to develop
refrigerating machine oil compositions having the above suitable
properties, the inventors have found that the objects of the
present invention can be achieved by using a base oil containing a
polyvinyl ether and/or a polyoxyalkylene glycol derivative having a
specific low viscosity as a main component and by forming sliding
portions of a refrigerator from a specific material. The present
invention has been accomplished on the basis of the finding.
[0014] Thus, the present invention provides:
[0015] (1) A refrigerating machine oil composition comprising a
base oil containing a polyvinyl ether and/or a polyoxyalkylene
glycol derivative as a main component and having a kinematic
viscosity of 1 to 8 mm.sup.2/s as measured at 40.degree. C.;
[0016] (2) the refrigerating machine oil composition described in
the above aspect (1), wherein said base oil has a molecular weight
of 100 to 600;
[0017] (3) the refrigerating machine oil composition described in
the above aspect (1), wherein said base oil has a flash point of
100.degree. C. or higher;
[0018] (4) the refrigerating machine oil composition described in
the above aspect (1), wherein said polyvinyl ether is a compound
having a repeating unit represented by the general formula (I):
##STR00001##
wherein R.sup.1, R.sup.2 and R.sup.3 are respectively a hydrogen
atom or a hydrocarbon group having 1 to 8 carbon atoms, and may be
the same or different; R.sup.4 is a divalent hydrocarbon group
having 1 to 10 carbon atoms; R.sup.5 is a hydrocarbon group having
1 to 20 carbon atoms; k is a number of 0 to 10 on average; R.sup.1
to R.sup.5 in one repeating unit may be respectively the same as or
different from those in the other repeating units; and when k is 2
or more, a plurality of the R.sup.4O groups may be the same or
different;
[0019] (5) the refrigerating machine oil composition described in
the above aspect (1), wherein said polyoxyalkylene glycol
derivative is a compound represented by the general formula
(II):
R.sup.6--[(OR.sup.7).sub.m--OR.sup.8].sub.n (II)
wherein R.sup.6 is a hydrogen atom, an alkyl group having 1 to 10
carbon atoms, an acyl group having 2 to 10 carbon atoms or an
aliphatic hydrocarbon group having 1 to 10 carbon atoms which
contains 2 to 6 bonding sites; R.sup.7 is an alkylene group having
2 to 4 carbon atoms; R.sup.8 is a hydrogen atom, an alkyl group
having 1 to 10 carbon atoms or an acyl group having 2 to 10 carbon
atoms; n is an integer of 1 to 6; and m is a number of more than 2
but not more than 20 on average;
[0020] (6) the refrigerating machine oil composition described in
the above aspect (1) which further comprises at least one additive
selected from the group consisting of an extreme pressure agent, an
oiliness agent, an antioxidant, an acid scavenger and a defoaming
agent;
[0021] (7) the refrigerating machine oil composition described in
the above aspect (1), wherein said composition is applied to a
refrigerator using a hydrocarbon-based, carbon dioxide-based,
hydrofluorocarbon-based or ammonia-based refrigerant;
[0022] (8) the refrigerating machine oil composition described in
the above aspect (7), wherein said composition is applied to a
refrigerator using a hydrocarbon-based refrigerant;
[0023] (9) the refrigerating machine oil composition described in
the above aspect (7), wherein the refrigerator includes a sliding
portion which is made of an engineering plastic material, or
provided thereon with an organic coating film or an inorganic
coating film;
[0024] (10) the refrigerating machine oil composition described in
the above aspect (9), wherein the organic coating film is a
polytetrafluoroethylene coating film, a polyimide coating film or a
polyamide imide coating film;
[0025] (11) the refrigerating machine oil composition described in
the above aspect (9), wherein the inorganic coating film is a
graphite film, a diamond-like carbon film, a tin film, a chromium
film, a nickel film or a molybdenum film;
[0026] (12) the refrigerating machine oil composition described in
the above aspect (1), wherein said composition is applied to
various hot water supply systems or refrigerating and heating
systems for air conditioners for automobiles, gas heat pumps,
general-purpose air conditioning equipments, refrigerators,
automatic vending machines or showcases; and
[0027] (13) the refrigerating machine oil composition described in
the above aspect (12), wherein a water content in the systems is 60
ppm by mass or less, and a residual air content therein is 8 kPa or
less.
EFFECT OF THE INVENTION
[0028] In accordance with the present invention, there is provided
a refrigerating machine oil composition having a low viscosity, an
improved energy saving performance, a good sealability and an
excellent compatibility with a refrigerant which is suitably used
in various refrigerating application fields, in particular,
closed-system refrigerators.
DETAILED DESCRIPTION OF THE INVENTION
[0029] In the refrigerating machine oil composition of the present
invention, there is used a base oil containing a polyvinyl ether
and/or a polyoxyalkylene glycol derivative as a main component. The
"polyvinyl ether and/or polyoxyalkylene glycol derivative contained
as a main component of the base oil" used herein means that the
base oil contains the polyvinyl ether and/or the polyoxyalkylene
glycol derivative in an amount of 50% by mass or more. The content
of the polyvinyl ether and/or the polyoxyalkylene glycol derivative
in the base oil is preferably 70% by mass or more, more preferably
90% by mass or more and still more preferably 100% by mass.
[0030] The base oil used in the present invention has a kinematic
viscosity of 1 to 8 mm.sup.2/s as measured at 40.degree. C. When
the base oil has a kinematic viscosity of 1 mm.sup.2/s or more, the
resultant refrigerating machine oil composition can exhibit a good
lubricating property as well as a good sealability, whereas when
the base oil has a kinematic viscosity of 8 mm.sup.2/s or less, the
resultant refrigerating machine oil composition can fully exhibit
the effect of improving an energy saving performance. The kinematic
viscosity of the base oil as measured at 40.degree. C. is
preferably from 1 to 5 mm.sup.2/s and more preferably from 2 to 4
mm.sup.2/s.
[0031] Also, the molecular weight of the base oil is preferably
from 100 to 600, more preferably from 100 to 330 and still more
preferably from 120 to 250. When the molecular weight of the base
oil lies within the above-specified range, the base oil can exhibit
a desired kinematic viscosity. The flash point of the base oil is
preferably 100.degree. C. or higher and more preferably 110.degree.
C. or higher.
[0032] In the present invention, as far as the base oil can exhibit
the above properties, the composition may also contain, in addition
to the polyvinyl ether and/or the polyoxyalkylene glycol
derivative, any other base oils in an amount of 50% by mass or
less, preferably 30% by mass or less and more preferably 10% by
mass or less. However, the refrigerating machine oil composition of
the present invention still more preferably contains no other base
oils than the polyvinyl ether and/or the polyoxyalkylene glycol
derivative.
[0033] Examples of the other base oils usable in combination with
the polyvinyl ether and/or the polyoxyalkylene glycol derivative
include hydrogenated .quadrature.-olefin oligomers, ether
compounds, mineral oils, alicyclic hydrocarbon compounds and
alkylated aromatic hydrocarbon compounds.
[0034] The polyvinyl ether suitably used as a main component of the
base oil in the present invention includes, for example, those
polyvinyl ethers having a repeating unit represented by the general
formula (I):
##STR00002##
wherein R.sup.1, R.sup.2 and R.sup.3 are respectively a hydrogen
atom or a hydrocarbon group having 1 to 8 carbon atoms, and may be
the same or different; R.sup.4 is a divalent hydrocarbon group
having 1 to 10 carbon atoms; R.sup.5 is a hydrocarbon group having
1 to 20 carbon atoms; k is a number of 0 to 10 on average; R.sup.1
to R.sup.5 in one repeating unit may be respectively the same as or
different from those in the other repeating units; and when k is 2
or more, a plurality of the R.sup.4O groups may be the same or
different.
[0035] In the above general formula (I), R.sup.1, R.sup.2 and
R.sup.3 are respectively a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms and preferably 1 to 4 carbon atoms, and
may be the same or different. Specific examples of the hydrocarbon
group include alkyl groups such as methyl, ethyl, n-propyl,
isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, various pentyl
groups, various hexyl groups, various heptyl groups and various
octyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl,
various methylcyclohexyl groups, various ethylcyclohexyl groups and
various dimethylcyclohexyl groups; aryl groups such as phenyl,
various methylphenyl groups, various ethylphenyl groups and various
dimethylphenyl groups; and arylalkyl groups such as benzyl, various
phenylethyl groups and various methylbenzyl groups. Meanwhile,
R.sup.1, R.sup.2 and R.sup.3 are more preferably hydrogen
atoms.
[0036] Also, in the above general formula (I), R.sup.4 is a
divalent hydrocarbon group having 1 to 10 carbon atoms and
preferably 2 to 10 carbon atoms. Specific examples of the divalent
hydrocarbon group having 1 to 10 carbon atoms include divalent
aliphatic groups such as methylene, ethylene, phenylethylene,
1,2-propylene, 2-phenyl-1,2-propylene, 1,3-propylene, various
butylene groups, various pentylene groups, various hexylene groups,
various heptylene groups, various octylene groups, various nonylene
groups and various decylene groups; alicyclic groups containing two
bonding sites which are derived from alicyclic hydrocarbons such as
cyclohexane, methyl cyclohexane, ethyl cyclohexane, dimethyl
cyclohexane and propyl cyclohexane; divalent aromatic hydrocarbon
groups such as various phenylene groups, various methylphenylene
groups, various ethylphenylene groups, various dimethylphenylene
groups and various naphthylene groups; alkyl aromatic groups
derived from alkyl aromatic hydrocarbons such as toluene, xylene
and ethyl benzene which contain an alkyl group moiety and an
aromatic moiety respectively having a monovalent bonding site; and
alkyl aromatic groups derived from polyalkyl aromatic hydrocarbons
such as xylene and diethyl benzene which contain an alkyl group
moiety having bonding sites. Among these divalent hydrocarbon
groups, preferred are divalent aliphatic groups having 2 to 4
carbon atoms.
[0037] In the general formula (I), k represents a repeating number
of R.sup.4O groups, and is a number ranging from 0 to 10 and
preferably from 0 to 5 on the average. When k is 2 or more, a
plurality of the R.sup.4O groups may be the same or different.
[0038] Further, in the general formula (I), R.sup.5 is a
hydrocarbon group having 1 to 20 carbon atoms and preferably 1 to
10 carbon atoms. Specific examples of the hydrocarbon group as
R.sup.5 include alkyl groups such as methyl, ethyl, n-propyl,
isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, various pentyl
groups, various hexyl groups, various heptyl groups, various octyl
groups, various nonyl groups and various decyl groups; cycloalkyl
groups such as cyclopentyl, cyclohexyl, various methylcyclohexyl
groups, various ethylcyclohexyl groups, various propylcyclohexyl
groups and various dimethylcyclohexyl groups; aryl groups such as
phenyl, various methylphenyl groups, various ethylphenyl groups,
various dimethylphenyl groups, various propylphenyl groups, various
trimethylphenyl groups, various butylphenyl groups and various
naphthyl groups; and arylalkyl groups such as benzyl, various
phenylethyl groups, various ethylbenzyl groups, various
phenylpropyl groups and various phenylbutyl groups. Meanwhile,
R.sup.1 to R.sup.5 in one repeating unit may be respectively the
same as or different from those in the other repeating units.
[0039] The polyvinyl ether used in the present invention may be
produced by polymerizing one or more kinds of corresponding vinyl
ether monomers.
[0040] The details of these polyvinyl ethers are described in
paragraphs [0027] to [0045] of Japanese Patent Application
Laid-open No. 49282/2001.
[0041] Examples of the suitable polyvinyl ether include polyethyl
vinyl ether and polyethyl vinyl ether-polyisobutyl vinyl ether
copolymers.
[0042] The polyvinyl ether used in the present invention may be
appropriately selected from those polyvinyl ethers having such a
polymerization degree that the resultant base oil exhibits a
kinematic viscosity of 1 to 8 mm.sup.2/s and preferably 1 to 4
mm.sup.2/s as measured at 40.degree. C.
[0043] On the other hand, the polyoxyalkylene glycol derivative
suitably used as a main component of the base oil in the present
invention includes, for example, those compounds represented by the
general formula (II):
R.sup.6--[(OR.sup.7).sub.m--OR.sup.8].sub.n (II)
wherein R.sup.6 is a hydrogen atom, an alkyl group having 1 to 10
carbon atoms, an acyl group having 2 to 10 carbon atoms or an
aliphatic hydrocarbon group having 1 to 10 carbon atoms which
contains 2 to 6 bonding sites; R.sup.7 is an alkylene group having
2 to 4 carbon atoms; R.sup.8 is a hydrogen atom, an alkyl group
having 1 to 10 carbon atoms or an acyl group having 2 to 10 carbon
atoms; n is an integer of 1 to 6; and m is a number of more than 2
but not more than 20 on average.
[0044] In the above formula (II), the alkyl groups having 1 to 10
carbon atoms as R.sup.6 and R.sup.8 may be respectively either
linear, branched or cyclic. Specific examples of the alkyl groups
as R.sup.6 and R.sup.8 include methyl, ethyl, n-propyl, isopropyl,
various butyl groups, various pentyl groups, various hexyl groups,
various heptyl groups, various octyl groups, various nonyl groups,
various decyl groups, cyclopentyl and cyclohexyl. When the alkyl
groups as R.sup.6 and R.sup.8 have more than 10 carbon atoms, the
polyoxyalkylene glycol derivative tends to be deteriorated in
compatibility with a refrigerant, resulting in occurrence of
undesirable phase separation. The alkyl groups as R.sup.6 and
R.sup.8 preferably have 1 to 6 carbon atoms.
[0045] Also, the alkyl group moiety in the respective acyl groups
having 2 to 10 carbon atoms as R.sup.6 and R.sup.8 may be either
linear, branched or cyclic. Specific examples of the alkyl group
moiety in the respective acyl groups as R.sup.6 and R.sup.8 include
those alkyl groups having 1 to 9 carbon atoms as specifically
exemplified above. When the acyl groups as R.sup.6 and R.sup.8 have
more than 10 carbon atoms, the polyoxyalkylene glycol derivative
tends to be deteriorated in compatibility with a refrigerant,
resulting in occurrence of undesirable phase separation. The acyl
groups as R.sup.6 and R.sup.8 preferably have 2 to 6 carbon
atoms.
[0046] When both of R.sup.6 and R.sup.8 are alkyl groups or acyl
groups, R.sup.6 and R.sup.8 may be the same or different.
[0047] In addition, when n is 2 or more, a plurality of the R.sup.8
groups being present in one molecule may be the same or
different.
[0048] When R.sup.6 is an aliphatic hydrocarbon group having 1 to
10 carbon atoms which contains 2 to 6 bonding sites, the aliphatic
hydrocarbon group may be chain-like or cyclic. Specific examples of
the aliphatic hydrocarbon group containing two bonding sites
include ethylene, propylene, butylene, pentylene, hexylene,
heptylene, octylene, nonylene, decylene, cyclopentylene and
cyclohexylene. Specific examples of the aliphatic hydrocarbon group
containing 2 to 6 bonding sites include residual groups obtained by
removing hydroxyl groups from polyhydric alcohols such as
trimethylol propane, glycerol, pentaerythritol, sorbitol,
1,2,3-trihydroxycyclohexane and 1,3,5-trihydroxycyclohexane.
[0049] When the aliphatic hydrocarbon group as R.sup.6 has more
than 10 carbon atoms, the polyoxyalkylene glycol derivative tends
to be deteriorated in compatibility with a refrigerant, resulting
in occurrence of undesirable phase separation. The aliphatic
hydrocarbon group as R.sup.6 preferably has 2 to 6 carbon
atoms.
[0050] In the present invention, at least one group of the above
R.sup.6 and R.sup.8 is preferably an alkyl group, more preferably
an alkyl group having 1 to 3 carbon atoms, and still more
preferably methyl in view of viscosity characteristics of the
composition. Further, for the same reason, both of R.sup.6 and
R.sup.8 are preferably alkyl groups and more preferably methyl
groups.
[0051] In the general formula (II), R.sup.7 represents an alkylene
group having 2 to 4 carbon atoms. Examples of the oxyalkylene group
as the repeating unit include oxyethylene, oxypropylene and
oxybutylene. A plurality of the oxyalkylene groups being present in
one molecule may be identical to each other, or may include two or
more kinds of oxyalkylene groups.
[0052] In the above general formula (II), n is an integer of 1 to
6, and may be determined according to the number of the bonding
sites in R.sup.6. For example, when R.sup.6 is an alkyl group or an
acyl group, n is 1, whereas when R.sup.6 is an aliphatic
hydrocarbon group having 2, 3, 4, 5 and 6 bonding sites, n is 2, 3,
4, 5 and 6, respectively. Also, m is a number of more than 2 but
not more than 20 on average. When m is more than 20 on the average,
the resultant composition tends to fail to fully achieve the aimed
objects of the present invention.
[0053] The details of these polyoxyalkylene glycol derivatives are
described in paragraphs [0012] to [0026] of Japanese Patent
Application Laid-open No. 49282/2001.
[0054] Among these polyoxyalkylene glycol derivatives represented
by the above general formula (II), preferred are polypropylene
glycol dimethyl ether, polyethylene-polypropylene glycol copolymer
dimethyl ether, polypropylene glycol monobutyl ether and
polypropylene glycol diacetate.
[0055] The polyoxyalkylene glycol derivative used in the present
invention may be appropriately selected from those compounds such
that the resultant base oil has a kinematic viscosity of 1 to 8
mm.sup.2/s and preferably 1 to 4 mm.sup.2/s as measured at
40.degree. C.
[0056] In the present invention, as the base oil, there may be used
one kind of the above polyvinyl ether solely, combination of two or
more kinds of the polyvinyl ethers, one kind of the above
polyoxyalkylene glycol derivative solely, combination of two or
more kinds of the polyoxyalkylene glycol derivatives, or
combination of one or more kinds of the polyvinyl ethers and one or
more kinds of the polyoxyalkylene glycol derivatives.
[0057] The refrigerating machine oil composition of the present
invention may also contain at least one additive selected from the
group consisting of an extreme pressure agent, an oiliness agent,
an antioxidant, an acid scavenger and a defoaming agent.
[0058] Examples of the extreme pressure agent include
phosphorus-based extreme pressure agents such as phosphates, acid
phosphates, phosphites, acid phosphites and amine salts
thereof.
[0059] Among these phosphorus-based extreme pressure agents, in
view of a good extreme-pressure property and frictional properties,
especially preferred are tricresyl phosphate, trithiophenyl
phosphate, tri(nonylphenyl)phosphite, dioleyl hydrogen phosphite
and 2-ethylhexyldiphenyl phosphite.
[0060] In addition, as the extreme pressure agent, there may also
be used metal salts of carboxylic acids. The metal salts of
carboxylic acids are preferably metals salts of carboxylic acids
having 3 to 60 carbon atoms, more preferably metal salts of fatty
acids having 3 to 30 carbon atoms, and still more preferably metal
salts of fatty acids having 12 to 30 carbon atoms. Further examples
of the extreme pressure agent include metal salts of dimer acids or
trimer acids of these fatty acids as well as metal salts of
dicarboxylic acids having 3 to 30 carbon atoms. Among these extreme
pressure agents, preferred are metal salts of fatty acids having 12
to 30 carbon atoms and dicarboxylic acids having 3 to 30 carbon
atoms.
[0061] Also, the metal element constituting the metal salts is
preferably an alkali metal or an alkali earth metal and more
preferably an alkali metal.
[0062] Examples of the other extreme pressure agents than those
described above include sulfur-based extreme pressure agents such
as sulfurized fats and oils, sulfurized fatty acids, sulfurized
esters, sulfurized olefins, dihydrocarbyl polysulfide,
thiocarbamates, thioterpenes and dialkylthiodipropionates.
[0063] The amount of the extreme pressure agent blended is usually
from 0.001 to 5% by mass and preferably from 0.005 to 3% by mass on
the basis of the total amount of the composition in view of
lubricating property and stability.
[0064] These extreme pressure agents may be used alone or in
combination of any two or more thereof.
[0065] Examples of the oiliness agent include aliphatic saturated
or unsaturated monocarboxylic acids such as stearic acid and oleic
acid, polymerized fatty acids such as dimer acids and hydrogenated
dimer acids, hydroxy fatty acids such as ricinoleic acid and
12-hydroxystearic acid, aliphatic saturated or unsaturated
monoalcohols such as lauryl alcohol and oleyl alcohol, aliphatic
saturated or unsaturated monoamines such as stearyl amine and oleyl
amine, aliphatic saturated or unsaturated monocarboxylic acid
amides such as laurylamide and oleamide, and partial esters of a
polyhydric alcohol such as glycerol and sorbitol with the aliphatic
saturated or unsaturated monocarboxylic acid.
[0066] These oiliness agents may be used alone or in combination of
any two or more thereof. The amount of the oiliness agent blended
is usually from 0.01 to 10% by mass and preferably from 0.1 to 5%
by mass on the basis of the total amount of the composition.
[0067] Examples of the antioxidant include phenol-based
antioxidants such as 2,6-di-tert-butyl-4-methyl phenol,
2,6-di-tert-butyl-4-ethyl phenol and
2,2'-methylenebis(4-methyl-6-tert-butyl phenol) and amine-based
antioxidants such as phenyl-.quadrature.-naphthyl amine and
N,N'-diphenyl-p-phenylene diamine. The amount of the antioxidant
blended is usually from 0.01 to 5% by mass and preferably from 0.05
to 3% by mass on the basis of the total amount of the composition
in view of good effects and economical advantages.
[0068] Examples of the acid scavenger include phenyl glycidyl
ether, alkyl glycidyl ether, alkylene glycol glycidyl ether,
cyclohexeneoxide, .quadrature.-olefinoxide and epoxy compounds such
as epoxidated soybean oil. Among these acid scavengers, phenyl
glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl
ether, cyclohexeneoxide and .quadrature.-olefinoxide are preferred
in view of a good compatibility.
[0069] The alkyl group contained in the alkyl glycidyl ether and
the alkylene group contained in the alkylene glycol glycidyl ether
may be branched or unbranched, and respectively have usually 3 to
30 carbon atoms, preferably 4 to 24 carbon atoms and more
preferably 6 to 16 carbon atoms. In the present invention, these
acid scavengers may be used alone or in combination of any two or
more thereof. The amount of the acid scavenger blended is usually
from 0.005 to 5% by mass and preferably from 0.05 to 3% by mass on
the basis of the total amount of the composition in view of good
effects and prevention of formation of sludge.
[0070] In the present invention, the refrigerating machine oil
composition can be improved in stability by blending the acid
scavenger therein, and the stability of the refrigerating machine
oil composition can be further improved by using the acid scavenger
in combination with the extreme pressure agent and the
antioxidant.
[0071] Examples of the defoaming agent include silicone oils and
fluorinated silicone oils.
[0072] The refrigerating machine oil composition of the present
invention may further contain various other known additives unless
the addition thereof adversely affects the objects of the present
invention. Examples of the other known additives include a steel
deactivator such as N-[N,N'-dialkyl(C.sub.3 to C.sub.12
alkyl)aminomethyl]tolutriazole.
[0073] The refrigerating machine oil composition of the present
invention can be suitably applied to refrigerators using a
hydrocarbon-based, carbon dioxide-based, hydrofluorocarbon-based or
ammonia-based refrigerant, and in particular, to those
refrigerators using a hydrocarbon-based refrigerant.
[0074] In the method of lubricating the refrigerators using the
refrigerating machine oil composition of the present invention,
various refrigerants and refrigerating machine oil compositions as
described above may be used in such an amount that a mass ratio of
the refrigerant to the refrigerating machine oil composition is
from 99/1 to 10/90 and preferably from 95/5 to 30/70. When the
amount of the refrigerant used is less than the above-specified
range, the refrigerating performance tends to be deteriorated. When
the amount of the refrigerant used is more than the above-specified
range, the lubricating performance tends to be deteriorated. The
refrigerating machine oil composition of the present invention can
be applied to various refrigerators, in particular, can be suitably
used in a compression refrigerating cycle of compression-type
refrigerators.
[0075] The refrigerators to which the refrigerating machine oil
composition of the present invention is applied has a refrigerating
cycle essentially constituted from a compressor, a condenser, an
expansion system (such as expansion valve) and an evaporator, or a
compressor, a condenser, an expansion system, a dryer and an
evaporator. In the refrigerators, there may be used the
refrigerating machine oil composition of the present invention as a
refrigerating machine oil as well as various refrigerants as
described above.
[0076] The dryer is preferably filled with a drying agent made of
zeolite having a pore diameter of 0.33 nm or less. Examples of the
zeolite include natural zeolites and synthetic zeolites. The
zeolite more preferably exhibits a CO.sub.2 gas absorption capacity
of 1.0% or less as measured at 25.degree. C. under a CO.sub.2 gas
partial pressure of 33 kPa. Specific examples of the synthetic
zeolite having such an absorption capacity include those available
under tradenames "XH-9", "XH-600", etc., from Union Showa Co.,
Ltd.
[0077] In the present invention, when using such a drying agent,
water is efficiently removed from the refrigerating cycle without
absorbing the refrigerant present in the refrigerating cycle. At
the same time, since such a drying agent is prevented by itself
from being powdered owing to deterioration thereof, there can be
avoided occurrence of clogging of conduits with the powder or
abnormal wear due to intrusion of the powder into sliding portions
of the compressor. As a result, the refrigerators can be stably
operated for a long period of time.
[0078] In the refrigerators to which the refrigerating machine oil
composition of the present invention is applied, various sliding
portions (for example, bearings) are provided within the compressor
thereof. In the present invention, these sliding portions are
preferably made of an engineering plastic material, or provided
thereon with an organic coating film or an inorganic coating film,
in particular, in view of a good sealability.
[0079] Examples of the preferred engineering plastic material
include polyamide resins, polyphenylene sulfide resins and
polyacetal resins in view of good sealability, slidability and
abrasion resistance.
[0080] Examples of the organic coating film include a
fluorine-containing resin coating film (such as a
polytetrafluoroethylene coating film), a polyimide coating film and
a polyamide imide coating film in view of good sealability,
slidability and abrasion resistance.
[0081] Examples of the inorganic coating film include a graphite
film, a diamond-like carbon film, a nickel film, a molybdenum film,
a tin film and a chromium film in view of good sealability,
slidability and abrasion resistance. These inorganic coating films
may be formed by either plating treatment or PVD (physical vapor
deposition) method.
[0082] In addition, the sliding portions may be made of a
conventional alloy material such as, for example, Fe-based alloys,
Al-based alloys and Cu-based alloys.
[0083] The refrigerating machine oil composition of the present
invention may be suitably used in various hot water supply systems
or refrigerating and heating systems for air conditioners for
automobiles, gas heat pumps, general-purpose air conditioning
equipments, refrigerators, automatic vending machines or
showcases.
[0084] In the present invention, the water content in these systems
is preferably 60 ppm by mass or less and more preferably 50 ppm by
mass or less. The residual air content in the systems is preferably
8 kPa or less and more preferably 7 kPa or less.
[0085] The refrigerating machine oil composition of the present
invention is composed of a base oil containing a polyvinyl ether
and/or a polyoxyalkylene glycol derivative as a main component
thereof, and can exhibit a low viscosity, an improved energy saving
performance and an excellent compatibility with a refrigerant.
EXAMPLES
[0086] The present invention will be described in more detail by
referring to the following examples. However, it should be noted
that these examples are only illustrative and not intended to limit
the invention thereto. Meanwhile, various properties of the base
oil as well as the refrigerating machine oil composition were
measured by the following methods.
<Properties of Base Oil>
(1) 40.degree. C. Kinematic Viscosity
[0087] Measured using a glass capillary viscometer according to JIS
K2283-1983.
(2) Flash Point
[0088] Measured by C.O.C. method according to JIS K2265.
<Properties of Refrigerating Machine Oil Composition>
(3) Solubility of Refrigerant in Refrigerating Machine Oil
Composition
[0089] A saturation solubility of isobutane in the refrigerating
machine oil composition was measured at 20.degree. C. under 0.2 MPa
using a solubility measuring apparatus. The mass percent as the
saturation solubility of isobutane was the value obtained by
measuring an amount of isobutane contained in an oil layer
sampled.
(4) Sealed Tube Test
[0090] The catalyst composed of Fe, Cu and Al was charged into a
glass tube. Further, a sample oil and a refrigerant (isobutane)
were filled into the glass tube in such an amount that a ratio of
the sample oil to the refrigerant was 4 mL/1 g, and then the glass
tube was sealed. The contents in the glass tube were allowed to
stand at 175.degree. C. for 30 days, and then observed to evaluate
or determine an appearance of each of the oil and the catalyst,
occurrence or non-occurrence of sludge therein, and an acid value
thereof.
(5) Short Circuit Test
[0091] Using a short circuit tester (reciprocating-type
refrigerator; capillary length: 1 m), the 1000 h endurance test was
conducted under the following conditions to measure a rate of
decease in capillary flow amount after the test:
[0092] Discharge pressure P.sub.d/suction pressure P.sub.S: 3.3
MPa/0.4 MPa; discharge-side temperature T.sub.d/suction-side
temperature T.sub.S: 110.degree. C./30.degree. C.; and sample oil
amount/refrigerant ("R600a": isobutane) amount: 400 g/400 g.
(6) Sealability Comparison Test
[0093] Using various sliding members as a piston, blow-by gas
amounts discharged from a clearance between the piston and cylinder
were compared with each other. The respective blow-by gas amounts
were expressed by a relative value calculated assuming that the
blow-by gas amount obtained in Reference Example 2 was regarded as
25.
Examples 1 to 12 And Comparative Examples 1 to 3
[0094] The refrigerating machine oils and the refrigerating machine
oil compositions as shown in Table 1 were prepared, and subjected
to measurement for a solubility of the refrigerant therein as well
as the sealed tube test. The result are shown in Table 1.
TABLE-US-00001 TABLE 1 Examples 1 2 3 4 5 6 Sample oil No. 1 2 3 4
5 6 Content (% by mass) Base oil A1 100 97.5 Base oil A2 100 97.5
Base oil A3 100 97.5 Base oil B1 Base oil B2 Extreme 1 1 1 pressure
agent C1 Extreme pressure agent C2 Acid 1 1 1 scavenger C3
Antioxidant C4 0.5 0.5 0.5 Defoaming 0.001 0.001 0.001 agent C5
Solubility of 30 32 35 -- -- -- refrigerant (% by mass) Results of
sealed tube test Appearance Good Good Good Good Good Good of oil
Appearance Good Good Good Good Good Good of catalyst Occurrence
None None None None None None of sludge Acid value 0.01>
0.01> 0.01> 0.01> 0.01> 0.01> (mg KOH/g) Appearance
Liquid Liquid Liquid Liquid Liquid Liquid at -10.degree. C.
Examples 7 8 9 10 11 12 Sample oil No. 7 8 9 10 11 12 Content (% by
mass) Base oil A1 97.5 98.0 Base oil A2 97.5 98.0 Base oil A3 97.5
98.0 Base oil B1 Base oil B2 Extreme 0.5 0.5 pressure agent C1
Extreme 1 1 1 0.5 pressure agent C2 Acid 1 1 1 1 1 1 scavenger C3
Antioxidant C4 0.5 0.5 0.5 0.5 0.5 0.5 Defoaming 0.001 0.001 0.001
0.001 0.001 0.001 agent C5 Solubility of -- -- -- -- -- --
refrigerant (% by mass) Results of sealed tube test Appearance Good
Good Good Good Good Good of oil Appearance Good Good Good Good Good
Good of catalyst Occurrence None None None None None None of sludge
Acid value 0.01> 0.01> 0.01> 0.01> 0.01> 0.01>
(mg KOH/g) Appearance Liquid Liquid Liquid Liquid Liquid Liquid at
-10.degree. C. Comparative Examples 1 2 3 Sample oil No. 13 14 15
Content (% by mass) Base oil A1 Base oil A2 Base oil A3 Base oil B1
97.5 100.0 Base oil B2 98.0 Extreme pressure agent C1 1 0.5 Extreme
pressure agent C2 Acid scavenger C3 1 1 Antioxidant C4 0.5 0.5
Defoaming agent C5 0.001 0.001 Solubility of refrigerant -- 5 21 (%
by mass) Results of sealed tube test Appearance of oil Good Good
Good Appearance of catalyst Good Good Good Occurrence of sludge
None None None Acid value (mg KOH/g) 0.01> 0.01> 0.01>
Appearance at -10.degree. C. Liquid Liquid Solid Note: A1:
Polypropylene glycol dimethyl ether; 40.degree. C. kinematic
viscosity: 3.2 mm.sup.2/s; flashpoint: 125.degree. C.; molecular
weight: 196 A2: Polypropylene glycol monobutyl ether; 40.degree. C.
kinematic viscosity: 3.1 mm.sup.2/s; flash point: 110.degree. C.;
molecular weight: 154 A3: Polyethyl vinyl ether; 40.degree. C.
kinematic viscosity: 3.1 mm.sup.2/s; flash point: 122.degree. C.;
molecular weight: 182 B1: Silicone oil; 40.degree. C. kinematic
viscosity: 10 mm.sup.2/s B2: n-Hexadecane C1: Tricresyl phosphate
C2: Trithiophenyl phosphate C3: C.sub.14 .quadrature.-olefinoxide
C4: 2,6-di-t-butyl-4-methylphenol C5: Silicone-based defoaming
agent
[0095] From Table 1, it was confirmed that the refrigerating
machine oils obtained in Examples 1 to 3 according to the present
invention exhibited a good solubility of the refrigerant
(isobutane) therein, whereas the refrigerating machine oils
obtained in Comparative Examples 2 and 3 had a poor solubility of
the refrigerant therein. In addition, the refrigerating machine
oils and the refrigerating machine oil compositions obtained in
Examples 1 to 12 all exhibited good results of the sealed tube
test.
Examples 13 to 21 and Comparative Examples 4 to 6
[0096] The sample oils as shown in Table 2 were subjected to the
short circuit test. The result are shown in Table 2.
TABLE-US-00002 TABLE 2 Examples Comparative Examples 13 14 15 16 17
18 19 20 21 4 5 6 Sample oil No. 4 5 6 7 8 9 1 2 3 13 14 15
Conditions of short circuit test Water content in 30 30 30 50 50 30
30 200 500 30 30 30 system (ppm) Residual air (kPa) 4 4 4 4 6.7 6.7
27 4 67 4 4 4 Results of short circuit test Rate of decrease 3>
3> 3> 3> 3> 3> 7 6 11 -- -- -- in capillary flow
amount Appearance of oil Good Good Good Good Good Good Yellowish
Yellowish Brown -- -- -- brown brown Acid value 0.01> 0.01>
0.01> 0.01> 0.01> 0.01> 0.08 0.04 0.17 -- -- -- (mg
KOH/g) Remarks Comp. Comp. Capillary seized seized clogged
[0097] From Table 2, it was confirmed that the refrigerating
machine oil compositions obtained in Examples 13 to 18 exhibited a
water content in system of less than 60 ppm by mass and a residual
air content of less than 8 kPa and, therefore, showed good results
of the short circuit test.
[0098] On the other hand, the refrigerating machine oil
compositions obtained in Examples 19 to 21 exhibited either a water
content in system of more than 60 ppm by mass or a residual air
content of more than 8 kPa. Therefore, results of the short circuit
test obtained in Examples 19 to 21 were slightly deteriorated as
compared to those obtained in Examples 13 to 18.
[0099] Also, the refrigerating machine oil compositions obtained in
Comparative Examples 4 to 6 suffered from seizing of the compressor
or clogging of the capillary when subjected to the short circuit
test.
Examples 22 to 25 and Reference Examples 1 and 2
[0100] Using the sample oils as shown in Table 3, the sliding
members as shown in Table 3 were subjected to the sealability
comparison test. The result are shown in Table 3.
TABLE-US-00003 TABLE 3 Examples Reference Examples 22 23 24 25 1 2
Sample oil No. 4 5 6 6 6 6 Sliding member D1 D2 D3 D4 D5 D6 Blow-by
gas amount 9 7 8 12 17 25 (relative amount) Note: D1: Polyphenylene
sulfide D2: Fluorine-containing polymer coating film D3:
Polyamide-containing coating film D4: Tin-plated film D5: Aluminum
alloy D6: Iron alloy
[0101] From Table 3, it was confirmed that the refrigerating
machine oil compositions obtained in Examples 22 to 25 all
exhibited a small blow-by gas amount and, therefore, a good
sealability as compared to those obtained in Reference Examples 1
and 2.
INDUSTRIAL APPLICABILITY
[0102] The refrigerating machine oil composition of the present
invention has a low viscosity, an improved energy saving
performance, a good sealability and an excellent compatibility with
a refrigerant and, therefore, can be suitably used in various
refrigerating application fields, in particular, in closed-system
refrigerators.
* * * * *