U.S. patent application number 13/822894 was filed with the patent office on 2013-10-17 for lubricant oil composition for compression refrigerator.
The applicant listed for this patent is Tomoya Matsumoto. Invention is credited to Tomoya Matsumoto.
Application Number | 20130274163 13/822894 |
Document ID | / |
Family ID | 45893056 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130274163 |
Kind Code |
A1 |
Matsumoto; Tomoya |
October 17, 2013 |
LUBRICANT OIL COMPOSITION FOR COMPRESSION REFRIGERATOR
Abstract
It is to provide a lubricating oil composition for a compression
refrigerator, which is excellent in the thermal/chemical stability
even when used in a compression refrigerator that uses a saturated
fluorinated hydrocarbon refrigerant having a lower global warming
potential and a fewer carbon atoms, by including in a base oil an
organic compound having a double bond in a molecule, which is at
least one kind selected from an organic compound having at least
two non-conjugated double bonds in the molecule, a terpene compound
having a double bond in the molecule, and C.sub.12 to C.sub.30
aliphatic unsaturated hydrocarbon having one double bond in the
molecule.
Inventors: |
Matsumoto; Tomoya; (Chiba,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Matsumoto; Tomoya |
Chiba |
|
JP |
|
|
Family ID: |
45893056 |
Appl. No.: |
13/822894 |
Filed: |
September 28, 2011 |
PCT Filed: |
September 28, 2011 |
PCT NO: |
PCT/JP2011/072162 |
371 Date: |
June 10, 2013 |
Current U.S.
Class: |
508/462 ;
508/506; 508/579 |
Current CPC
Class: |
C10M 2209/1033 20130101;
C10N 2030/64 20200501; C10N 2020/101 20200501; C10N 2040/30
20130101; C10M 127/00 20130101; C10N 2030/10 20130101; C10M
2223/041 20130101; C10M 2207/042 20130101; C10N 2020/02 20130101;
C10M 2203/024 20130101; C09K 2205/122 20130101; C10M 2203/04
20130101; C10M 2209/043 20130101; C10N 2030/08 20130101; C10M
171/008 20130101; C10M 2207/026 20130101; C10M 2207/2835 20130101;
C10M 2229/02 20130101; C10N 2020/067 20200501; C10N 2080/00
20130101; C10M 2209/1055 20130101; C10N 2020/04 20130101; C09K
5/045 20130101; C10M 2209/1055 20130101; C10M 2209/1085 20130101;
C10M 2209/043 20130101; C10M 2209/1055 20130101 |
Class at
Publication: |
508/462 ;
508/579; 508/506 |
International
Class: |
C10M 127/00 20060101
C10M127/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2010 |
JP |
2010-217917 |
Claims
1. A lubricating oil composition, comprising: a base oil; and an
organic compound having a double bond, which is at least one kind
selected from the group consisting of an organic compound having at
least two non-conjugated double bonds, a terpene compound having a
double bond, and a C.sub.12 to C.sub.30 aliphatic unsaturated
hydrocarbon having one double bond, wherein the lubricating oil
composition is suitable for a compression refrigerator and the
compression refrigerator comprises a refrigerant comprising a
C.sub.1 to C.sub.3 saturated fluorinated hydrocarbon.
2. The lubricating oil composition according to claim 1, wherein
the organic compound having a double bond has, as an organic
compound having at least two non-conjugated double bonds, a
1,4-diene structure.
3. The lubricating oil composition according to claim 1, wherein
the organic compound having a double bond has. as an organic
compound having at least two non-conjugated double bonds, a bridged
cyclic structure.
4. The lubricating oil composition according to claim 1, wherein
the organic compound having a double bond, as a terpene compound,
is a pinene compound.
5. The lubricating oil composition according to claim 1, wherein
the lubricating oil composition comprises the organic compound
having a double bond in an amount of from 0.1% by mass to 10% by
mass or less based on a total amount of the lubricating oil
composition.
6. The lubricating oil composition according to claim 1, wherein
the C.sub.1 to C.sub.3 saturated fluorinated hydrocarbon is
difluoromethane.
7. The lubricating oil composition according to claim 1, wherein
the refrigerant is a mixture of difluoromethane and
pentafluoroethane, or a mixture of difluoromethane,
pentafluoroethane, and 1,1,1,2 tetrafluoroethane.
8. The lubricating oil composition according to claim 7, wherein
the refrigerant comprises difluoromethane in an amount of 20% by
mass or more.
9. The lubricating oil composition according to claim 1, wherein
the base oil comprises at least one selected from the group
consisting of a polyoxyalkylene glycol, a polyvinyl ether, a
copolymer of a polyoxyalkylene glycol and a polyvinyl ether, a
copolymer of a polyoxyalkylene glycol monoether and a polyvinyl
ether, a polyol ester and a polycarbonate as a main component.
10. The lubricating oil composition according to claim 1, wherein
the base oil has a kinematic viscosity of from 1 mm.sup.2/s to 50
mm.sup.2/s at 100.degree. C.
11. The lubricating oil composition according to claim 1, wherein
the base oil has a number average molecular weight of from 300 to
3000.
12. The lubricating oil composition according to claim 1, wherein
the base oil has a viscosity index of 60 or more.
13. The lubricating oil composition according to claim 1, further
comprising: at least one additive selected from the group
consisting of an extreme pressure agent, an oiliness agent, an
antioxidant, an acid scavenger, a metal deactivator, and an
antifoaming agent.
14. The lubricating oil composition according to claim 1, wherein
the compression refrigerator comprises a sliding part comprising an
engineering plastic, an organic coating film, or an inorganic
coating film.
15. The lubricating oil composition according to claim 14, wherein
the sliding part comprises, as an organic coating film, a
polytetrafluoroethylene coating film, a polyimide coating film, a
polyamideimide coating film, a thermosetting insulating film, or
any combination thereof, wherein if the sliding member comprises
the thermosetting insulating film, the thermosetting insulating
film is obtained from a resin coating material comprising a resin
base material and a crosslinking agent and if the sliding member
comprises the thermosetting insulating film, the resin base
material comprising a polyhydroxy ether resin and a polysulfonic
resin.
16. The lubricating oil composition according to claim 14, wherein
the sliding part comprises, as an inorganic coating film, a
graphite film, a diamond-like carbon film, a tin film, a chromium
film, a nickel film, a molybdenum film, or any combination
thereof.
17. The lubricating oil composition according to claim 1, wherein
the lubricating oil composition is suitable for a car air
conditioner, an electric car air conditioner, a gas heat pump, an
air conditioner, a refrigerator, an automatic vending machine, a
show case, a hot-water supply system, a freezing and heating
system, or any combination thereof.
18. The lubricating oil composition according to claim 17, wherein
the lubricating oil composition is suitable for the hot-water
supply system having a moisture content of 300 ppm by mass or less
and a residual air partial pressure of 10 kPa or less.
19. The lubricating oil composition according to claim 17, wherein
the lubricating oil composition is suitable for the freezing and
heating system having a moisture content of 300 ppm by mass or less
and a residual air partial pressure of 10 kPa or less.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lubricating oil
composition, for a compression refrigerator, and more particularly
to a lubricating oil composition for a compression refrigerator,
which uses a saturated fluorinated hydrocarbon having a fewer
carbon atoms as a refrigerant and is excellent in the thermal and
oxidation stability.
BACKGROUND ART
[0002] In recent years, in compression refrigerators such as air
conditioners, car air conditioners and the like, a C.sub.1 or
C.sub.2 saturated fluorinated hydrocarbon (HFC), which is a
refrigerant that does not deplete an ozone layer has been used.
However, recently, these compression refrigerators have been used
under severe conditions for more and more longer time.
[0003] Accordingly, as a lubricating oil composition for a
compression refrigerator like this, a lubricant oil excellent in
the thermal and oxidation stability is in demand.
[0004] Further, in various compression refrigerators including air
conditioners, as the HFC refrigerant that does not deplete an ozone
layer, mixed refrigerants containing difluoromethane (R32) such as
R410A, R407C and so on have been used.
[0005] However, in addition to protection of the ozone layer,
prevention of global warming is required, and it has been desired
to use a refrigerant containing much more R32 that has lower global
warming potential.
[0006] The R32 has relatively high theoretical COP and thermal
conductivity and low pressure loss of a refrigerant; accordingly,
when used in an air conditioner, the air conditioner is
characterized by high energy efficiency.
[0007] However, the R32 is characterized in that the discharge
temperature of a compressor is higher by about 20.degree. C. than
that of conventional R410A or R407C.
[0008] From a situation like this, an improvement in a structure of
a refrigerator as shown in Patent Document 1 for example has been
under study.
[0009] Further, as a lubricant oil for a compression refrigerator
that uses these refrigerants, a lubricating oil composition having
high thermal and oxidation stability under the presence of these
refrigerants is in demand.
[0010] The requirement like this was considered that it can be
handled, as described in Patent Documents 2 to 4, for example, by
blending an existing antioxidant or acid scavenger that is used in
R134a or the like in a saturated HFC that is high in the stability
different from an unsaturated HFC or an iodide. However, even when
an existing antioxidant or acid scavenger is simply compounded or a
compounding amount thereof was increased, an improving effect
thereof is low.
PRIOR ART DOCUMENTS
Patent Documents
[0011] [Patent Document 1] JP 2001-183020A
[0012] [Patent Document 2] JP 02-258896A
[0013] [Patent Document 3] JP 02-281098A
[0014] [Patent Document 4] JP 02-305893A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0015] It is the object of the present invention to provide a
lubricating oil composition for a compression refrigerator, which
is excellent in the thermal and oxidation stability, even when
used, under the situation like this, in a compression refrigerator
that uses a saturated fluorinated hydrocarbon refrigerant that has
lower global warming potential and has a fewer carbon atoms.
Means for Solving the Problems
[0016] The inventors have made an earnest study with a view toward
accomplishing the above-described object and, as a result, found
that the above-described object can be achieved by allowing a base
oil to contain a specific organic compound having a double bond in
a molecule as a stabilizer. The present invention has been
completed based on the above finding.
[0017] Thus, the present invention provides as follows:
[0018] (1) a lubricating oil composition for a compression
refrigerator that uses a refrigerant containing C.sub.1 to C.sub.3
saturated fluorinated hydrocarbon, the lubricating oil composition
including a base oil and an organic compound having a double bond
in a molecule, which is at least one kind selected from an organic
compound having at least two non-conjugated double bonds in the
molecule, a terpene compound having a double bond in the molecule,
and C.sub.12 to C.sub.30 aliphatic unsaturated hydrocarbon having
one double bond in the molecule,
[0019] (2) the lubricating oil composition for a compression
refrigerator described in the (1), in which the organic compound
having at least two non-conjugated double bonds in the molecule is
a compound having a 1,4-diene structure,
[0020] (3) the lubricating oil composition for a compression
refrigerator described in the (1), in which the organic compound
having at least two non-conjugated double bonds in the molecule is
a compound having a bridged cyclic structure,
[0021] (4) the lubricating oil composition for a compression
refrigerator described in the (1), in which the terpene compound
having one double bond in the molecule is a pinene compound,
[0022] (5) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (4), in which a
compounding amount of the organic compound having one double bond
in the molecule is 0.1% by mass or more and 10% by mass or less
based on a total amount of the composition,
[0023] (6) the lubricating oil composition for a compression
refrigerator described in the (1), in which the C.sub.1 to C.sub.3
saturated fluorinated hydrocarbon is difluoromethane (R32),
[0024] (7) the lubricating oil composition for a compression
refrigerator described in the (1), in which the refrigerant is a
mixture of difluoromethane (R32) and pentafluoroethane (R125), or a
mixture of difluoromethane (R32), pentafluoroethane (R125) and
1,1,1,2 tetrafluoroethane (R134a),
[0025] (8) the lubricating oil composition for a compression
refrigerator described in the (7), in which the refrigerant is a
refrigerant that contains 20% by mass or more of difluoromethane
(R32),
[0026] (9) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (8), in which the base
oil contains at least one kind selected from polyoxyalkylene
glycols, polyvinyl ethers, a copolymer between poly(oxy)alkylene
glycol or monoether thereof and polyvinyl ether, polyol esters and
polycarbonates as a main component,
[0027] (10) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (9), in which the
kinematic viscosity at 100.degree. C. of the base oil is 1
mm.sup.2/s or more and 50 mm.sup.2/s or less,
[0028] (11) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (10), in which the
number average molecular weight of the base oil is 300 or more and
3000 or less,
[0029] (12) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (11), in which the
viscosity index of the base oil is 60 or more,
[0030] (13) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (12), in which at least
one kind of additive selected from an extreme pressure agent, an
oiliness agent, an antioxidant, an acid scavenger, a metal
deactivator and an antifoaming agent is further contained,
[0031] (14) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (13), in which a
sliding part of a compression refrigerator is made of an
engineering plastic or has an organic coating film or an inorganic
coating film,
[0032] (15) the lubricating oil composition for a compression
refrigerator described in (14), in which the organic coating film
is anyone of a polytetrafluoroethylene coating film, a polyimide
coating film, a polyamideimide coating film, and a thermosetting
insulating film formed with a resin coating material that contains
a resin base material of a polyhydroxy ether resin and a
polysulfonic resin and a crosslinking agent,
[0033] (16) the lubricating oil composition for a compression
refrigerator described in (14), in which the inorganic coating film
is any one of a graphite film, a diamond-like carbon film, a tin
film, a chromium film, a nickel film and a molybdenum film,
[0034] (17) the lubricating oil composition for a compression
refrigerator described in any one of (1) to (16), wherein the
lubricating oil composition is used in a car air conditioner, an
electric car air conditioner, a gas heat pump, an air conditioner,
a refrigerator, an automatic vending machine, a show case, a
hot-water supply system or a freezing and heating system, and
[0035] (18) the lubricating oil composition for a compression
refrigerator described in (17), in which a moisture content in an
applied system is 300 ppm by mass or less, and residual air partial
pressure is 10 kPa or less.
Advantages of the Invention
[0036] According to the present invention, it is possible to
provide a lubricating oil composition for a compression
refrigerator, which is excellent in the thermal/chemical stability
even when used in a compression refrigerator that uses a saturated
fluorinated hydrocarbon refrigerant having a lower global warming
potential and a fewer carbon atoms.
Embodiments for Carrying out the Invention
[0037] The lubricating oil composition for a compression
refrigerator according to the present invention contains a base oil
and an organic compound having a double bond in a molecule, which
is at least one kind selected from an organic compound having at
least two non-conjugated double bonds in one molecule, a terpene
compound having a double bond in the molecule, and C.sub.12 to
C.sub.30 aliphatic unsaturated hydrocarbon having one double bond
in the molecule.
Organic Compound having Double Bond in Molecule
Organic Compound having at Least Two Non-conjugated Double Bonds in
Molecule
[0038] The non-conjugated double bond means a relationship where
double bonds are separated by two or more single bonds. Further,
the double bond may be contained or may not be contained in an
aromatic ring. In the case of a non-conjugated diene, a
non-conjugated double bond is counted as two double bonds.
[0039] The number of non-conjugated double bonds contained in the
molecule is preferably two or more and four or less, more
preferably three or less, and particularly preferably two. The
upper limit of the numbers of non-conjugated double bonds is about
10.
[0040] The organic compound having two or more non-conjugated
double bonds in the molecule like this preferably has a 1,4-diene
structure or a bridged cyclic structure.
[0041] Here, the 1,4-diene structure means a structure having a
double bond at each of 1 position and 4 position. The bridged
cyclic structure means a structure where in at least one ring, a
bond (may have a double bond) that splits the ring is present.
[0042] Examples of organic compounds having the 1,4-diene structure
include 1,4-cyclohexadiene, 2-vinyl-1-methylenecyclopropane,
1,3-dimethylenecyclobutane, 4-methylenecyclopentene,
2-methyl-1,4-pentadiene, 1,4-hexadiene, 3-methyl-1,4-pentadiene,
3-methyl-1,4-cyclohexadiene, 1,4-cycloheptadiene,
3-vinyl-1,4-pentadiene, 2,5-heptadiene, 4-methylenecyclohexene,
5-methyl-1,4-hexadiene, 2,4-dimethyl-1,4-pentadiene,
1,4-cyclooctadiene, 2,3-dimethyl-1,4-hexadiene,
3-methyl-1,4-heptadiene, 1,4,7-cyclononatriene,
1,3,5-trimethyl-1,4-cyclohexadiene, (Z)-1,4-nonadiene,
1,3,5-tris(methylene)cycloheptane, 3,4-divinyl-1,5-hexadiene,
3-ethyl-1,4-octadiene, 1,4-decadiene, 1,4-undecadiene,
2,4,5,6-pentamethyl-1,4-cyclooctadiene, 7-ethenyl-5-undecene,
2-nonyl-1,4-pentadiene, 4-pentyl-1,4-decadiene,
2-decyl-1,4-pentadiene, 6,9-pentadecadiene, 1,7,10-hexadecatriene,
dihydroaplotaxene, 1,8,11-heptadecatriene, 3,6,9-heptadecatriene,
6,9-heptadecadiene, 3,6,9-octadecatriene, 6,9,12-octadecatriene,
6,9-octadecadiene, 3,6,9-nonadecatriene,
2,6-dimethyl-2,6,9-heptadecatriene,
2,2-dimethyl-6-pentyl-3,6-dodecadiene,
2,4,6,8,10,12-hexamethyl-1,12-tridecadiene,
7,11,15-trimethyl-1,4-heptadecadiene, and 1,4-p-mentadiene. Among
these, 1,4-p-mentadiene, 1,4-cyclohexadiene, and 1,4-hexadiene,
which are high in the reactivity with oxygen are more preferably
used.
[0043] Further, examples of organic compounds having the bridged
cyclic structure include 2,5-norbornadiene,
5-ethylidene-2-norbornen, 5-vinyl-2-norbornen,
7-methyl-2,5-norbornadiene, 7-ethyl-2,5-norbornadiene,
7-propyl-2,5-norbornadiene, 7-butyl-2,5-norbornadiene,
7-pentyl-2,5-norbornadiene, 7-hexyl-2,5-norbornadiene,
7,7-dimethyl-2,5-norbornadiene, 7-methyl-7-ethyl-2,5-norbornadiene,
1-methyl-2,5-norbornadiene, 1-ethyl-2,5-norbornadiene,
1-propyl-2,5-norbornadiene, 1-butyl-2,5-norbornadiene,
bicyclo[3.2.0]hepta-2,6-diene, homotropilidene,
5-methylenebicyclo[2,2,1]hepta-2-ene, bicycle[2.2.2]octa-2,5-diene,
and bicycle[3.2.1]octa-2,6-diene.
[0044] Among these, 2,5-norbornadiene high in the reactivity with
oxygen is more preferably used.
[0045] Examples of other organic compounds having at least two
non-conjugated double bonds in the molecule include 1,5-hexadiene,
1-methyl-1,5-cyclohexadiene, 3-methylene-1,5-hexadiene,
2-methyl-1,5-hexadiene, 4-methyl-1,5-hexadiene,
2-methyl-1,5-hexadiene, 3-methyl-1,5-hexadiene, 1,6-heptadiene,
1,5-heptadiene, 4-vinyl-1-cyclohexene, 1,5-cyclooctadiene,
1,4-bismethylenecyclohexane, 1,7-octadiene,
2,5-dimethyl-1,5-hexadiene, 3-ethyl-1,5-hexadiene, 2,6-octadiene,
1,6-octadiene, 1-methyl-2,3-divinylcyclobutane,
1-(1-methylethenyl)-3-cyclohexene, 1-methyl-5-vinyl-1-cyclohexene,
1-methyl-1-ethenyl-3-cyclohexene, 3,5-dimethyl-1,6-heptadiene,
3,3-dimethyl-1,6-heptadiene, 4-methyl-2,6-octadiene,
2,5-dimethyl-1,6-heptadiene, 3,6-dimethyl-1,5-heptadiene, myrcene,
cyclodeca-1,6-diene, 1,5-cyclodecadiene,
2,7-dimethyl-2,6-octadiene, 1,5,9-cyclododecatriene,
1,1'-bi[2-cyclohexene], 3-cyclohexyl-1,5-hexadiene,
6-methylene-1,10-undecadiene, 1,5-cyclododecadiene,
6,10-dimethyl-1,5,9-undecatriene, 1,12-tridecadiene,
2,6-dimethyl-1,6-undecadiene, 1,8-cyclotetradecadiene,
8-cyclohexyl-1,5-octadiene, 7,11-dimethyl-1,6,10-dodecadiene,
1,13-tetradecadiene, 3-isopropyl-2,5,7-trimethyl-1,5-octadiene,
4,5-dipropyl-1,7-octadiene, 1,9-cyclohexadecadiene,
1,7-hexadecadiene, 2,4,6,8,10-pentamethyl-1,10-undecadiene,
8,14-heptadecadiene, 1,1,1-octadecadiene,
9-ethylidene-1,16-heptadecadiene, 1,11-cycloicosadiene,
1,9-icosadiene, icosa-7,13-diene, and
4,9-dibutyl-1,11-dodecadiene.
Terpene Compound having Double Bond in Molecule
[0046] As the terpene compound having a double bond in the
molecule, a dimer to an octamer of isoprene are preferred, and, in
particular, an aliphatic unsaturated hydrocarbon, in particular,
.alpha.-pinene and .beta.-pinene are preferred.
C.sub.12 to C.sub.30 Aliphatic Unsaturated Hydrocarbon having One
Double Bond in Molecule
[0047] As the C.sub.12 to C.sub.30 aliphatic unsaturated
hydrocarbon having one double bond in a molecule, C.sub.12 to
C.sub.30 .alpha.-olefins are preferred, for example, 1-tetradecene,
1-hexadecene, 1-octadecene, and 1-eicosene can be cited.
[0048] Among three kinds of organic compounds having a double bond
in the molecule in the invention, a terpene compound having a
double bond in the molecule is preferred, and, pinene, in
particular, .beta.-pinene is preferred.
[0049] A compounded amount of the organic compound having a double
bond in the molecule as described above is, on the basis of an
entire composition, preferable to be 0.1% by mass or more and 10%
by mass or less. When the compounded amount is in the above range,
while maintaining the compatibility with a refrigerant, a function
as an oxygen scavenger can be sufficiently exerted.
[0050] The compounded amount is preferable to be 0.1% by mass or
more and 5% by mass or less, and more preferable to be 0.1% by mass
or more and 3% by mass or less.
[0051] The lubricating oil composition for a compression
refrigerator of the invention only has to contain the organic
compound having a double bond in the molecule, and, as required,
may contain other oxygen scavengers.
Base Oil
[0052] The base oil in the invention preferably contains at least
one kind selected among polyoxyalkylene glycols, polyvinyl ethers,
copolymers of poly(oxy)alkylene glycol or a monoether thereof and
polyvinyl ether, polyol esters and polycarbonates as a main
component.
Polyoxyalkylene Glycols
[0053] As the polyoxyalkylene glycols usable as the base oil,
compounds represented by a formula (I), for example, can be
cited.
R.sup.1--[(OR.sup.2).sub.m--OR.sup.3].sub.n (1)
(In the formula, R.sup.1 represents a hydrogen atom, a C.sub.1 to
C.sub.10 monovalent hydrocarbon group, a C.sub.2 to C.sub.10 acyl
group, a C.sub.1 to C.sub.10 hydrocarbon group having 2 to 6
binding sites or a C.sub.1 to C.sub.10 oxygen-containing
hydrocarbon group, R.sup.2 represents a C.sub.2 to C.sub.4 alkylene
group, R.sup.3 represents a hydrogen atom, a C.sub.1 to C.sub.10
hydrocarbon group or a C.sub.2 to C.sub.10 acyl group or a C.sub.1
to C.sub.10 oxygen-containing hydrocarbon group, n represents an
integer of 1 to 6, and m represents a number where an average value
of m.times.n becomes 6 to 80.)
[0054] In the above formula (I), a C.sub.1 to C.sub.10 monovalent
hydrocarbon group in each of R.sup.1 and R.sup.3 may be linear
chained, branched or cyclic. The hydrocarbon group is preferably an
alkyl group, and, specific examples thereof include a methyl group,
an ethyl group, an n-propyl group, an isopropyl group, various
butyl groups, various pentyl groups, various hexyl groups, various
heptyl groups, various octyl groups, various nonyl groups, various
decyl groups, a cyclopentyl group, and a cyclohexyl group. When the
number of carbon atoms of the alkyl group exceeds 10, the
compatibility with the refrigerant is deteriorated and, in some
cases, a phase separation is induced. The preferable number of
carbon atoms of the alkyl group is 1 to 6.
[0055] Further, in each of R.sup.1 and R.sup.3, a hydrocarbon group
moiety of a C.sub.2 to C.sub.10 acyl group may be linear chained,
branched, or cyclic. A hydrocarbon group moiety of the acyl group
is preferably an alkyl group, and, as a specific example thereof,
various C.sub.1 to C.sub.9 groups cited as specific examples of the
alkyl groups can be similarly cited. When the number of carbon
atoms of the acyl group exceeds 10, the compatibility with a
refrigerant is deteriorated, and, in some cases, the phase
separation is induced. The number of carbon atoms of an acyl group
is preferably 2 to 6.
[0056] When both R.sup.1 and R.sup.3 are a hydrocarbon group or an
acyl group, R.sup.1 and R.sup.3 may be the same with or different
from each other.
[0057] Further, when n is 2 or more, a plurality of R.sup.3's in
one molecule may be the same with or different from each other.
[0058] When R.sup.1 is a C.sub.1 to C.sub.10 hydrocarbon group
having 2 to 6 binding sites, the hydrocarbon group may be straight
chained or branched. As a hydrocarbon group having two binding
sites, aliphatic hydrocarbon groups are preferred, and examples
thereof include an ethylene group, a propylene group, a butylene
group, a pentylene group, a hexylene group, a heptylene group, an
octylene group, a nonylene group, a decylene group, a
cyclopentylene group, and a cyclohexylene group. Examples of other
hydrocarbon groups include residues obtained by removing a hydroxyl
group from bisphenols such as biphenol, bisphenol F, or bisphenol
A. Further, as the hydrocarbon group having 3 to 6 binding sites,
aliphatic hydrocarbon groups are preferred, and examples thereof
include residues obtained by removing a hydroxyl group from
polyhydric alcohols such as trimethylol propane, glycerin,
pentaerythritol, sorbitol, 1,2,3-trihydroxy cyclohexane, and
1,3,5-trihydroxy cyclohexane.
[0059] When the number of carbon atoms of the aliphatic hydrocarbon
group exceeds 10, the compatibility with the refrigerant is
deteriorated and, in some cases, a phase separation is induced. The
preferable number of carbon atoms is 2 to 6.
[0060] Further, as the C.sub.1 to C.sub.10 oxygen-containing
hydrocarbon group in each of R.sup.1 and R.sup.3, chained aliphatic
groups and cyclic aliphatic groups, which have an ether bond can be
cited. However, a tetrahydrofurfuryl group is particularly
preferred.
[0061] In the invention, at least one of the R.sup.1 and R.sup.3 is
preferred to be an alkyl group, particularly, a C.sub.1 to C.sub.3
alkyl group, and especially, a methyl group, from the viewpoint of
the viscosity characteristics. Further, from the same reason, both
of R.sup.1 and R.sup.3 are preferred to be an alkyl group,
particularly, a methyl group.
[0062] R.sup.2 in the formula (I) is a C.sub.2 to C.sub.4 alkylene
group, and, as an oxyalkylene group of a repeating unit, an
oxyethylene group, an oxypropylene group, and an oxybutylene group
can be cited. In one molecule, the oxyalkylene groups may be the
same, or, two or more kinds of oxyalkylene groups may be contained.
However, in one molecule, at least an oxypropylene unit is
preferably contained, in particular, in an oxyalkylene unit, 50% by
mol or more of the oxypropylene unit is preferably contained.
[0063] In the formula (I), n represents an integer of 1 to 6, and
this is determined according to the number of binding sites of
R.sup.1. When R.sup.1 represents an alkyl group or an acyl group,
for example, n is 1. When R.sup.1 is an aliphatic hydrocarbon group
having two, three, four, five and six binding sites, respectively,
n represents 2,3,4,5 and 6, respectively. Further, m represents the
number where an average value of m.times.n is 6 to 80. When the
average value exceeds 80, the compatibility is deteriorated and the
oil returnability is damaged. That is, when the average value of
m.times.n deviates from the range thereof, the object of the
invention may not be sufficiently achieved.
[0064] The polyoxyalkylene glycols represented by the formula (I)
include polyoxyalkylene glycol having a hydroxyl group at a
terminal thereof, and, when the content of the hydroxyl groups is
at, a ratio of 50% by mole or less with respect to an entirety of
terminal groups, even when contained, the polyoxyalkylene glycol
can be preferably used. When the content of the hydroxyl groups
exceeds 50% by mole, a hygroscopic property increases to
unfavorably deteriorate the viscosity index. When the
polyoxyalkylene glycol is used together with an unsaturated
fluorinated hydrocarbon refrigerant described below, the
refrigerant has an olefin structure and is poor in the stability.
Accordingly, the base oil preferably has the hydroxyl group value
of 5 mgKOH/g or less, more preferably 3 mgKOH/g or less, and
particularly preferably 1 mgKOH/g or less.
[0065] Further, from the viewpoint of stability of the base oil, it
is preferable that the ASTM color is 1 or less and the ash content
is 0.1% by mass or less.
[0066] As such polyoxyalkylene glycols, polyoxypropylene glycol
dimethyl ether represented by a formula (I-a)
##STR00001##
[0067] (In the formula, x represents an integer of 6 to 80.),
polyoxyethylene polyoxypropylene glycol dimethyl ether represented
by a formula (I-b)
##STR00002##
[0068] (In the formula, a and b each represents an integer of 1 or
more and a sum total of which is 6 to 80.), and polyoxypropylene
glycol monobutyl ether represented by a formula (I-c)
##STR00003##
[0069] (In the formula, x represents an integer of 6 to 80.), and
polyoxypropylene glycol diacetate are preferable from the viewpoint
of economic efficiency and advantage.
[0070] As the polyoxyalkylene glycols represented by the formula
(I), all of what was described in detail in JP 2-305893 A can be
used.
[0071] In the invention, the polyoxyalkylene glycols may be used
singularly or in a combination of two or more kinds thereof.
[0072] The polyoxyalkylene glycol derivative can be obtained in
such a manner that C.sub.2 to C.sub.4 alkylene oxide such as
ethylene oxide or propylene oxide is polymerized with water or
alkali hydroxide as an initiator to obtain polyoxyalkylene glycol
having a hydroxyl group at each of both terminals, thereafter, both
ends of the hydroxyl groups are etherized or esterized with alkyl
halide or acyl halide.
[0073] Further, the polyoxyalkylene glycol derivative can be
manufactured also, in such a manner that, with monovalent C.sub.1
to C.sub.10 alcohol or an alkali metal salt thereof as an
initiator, C.sub.2 to C.sub.4 alkylene oxide is polymerized to
obtain polyoxyalkylene glycol monoalkyl ether having an ether bond
at one terminal and a hydroxyl group at the other terminal,
thereafter, the hydroxyl group is etherized or esterized. When a
compound of which n in the formula (I) is 2 or more is
manufactured, in place of monovalent alcohol, di- to hexa-valent
polyhydric alcohol may be used as an initiator.
[0074] When a polyoxyalkylene glycol derivative is manufactured
according to a method like this, in a ratio between polyoxyalkylene
glycol and the like and alkyl halide or acyl halide in an
etherification or esterification reaction, when an amount of alkyl
halide or acyl halide is less than a stoichiometric amount,
hydroxyl groups remain to increase the hydroxyl group value.
Accordingly, a molar ratio between polyoxyalkylene glycol and the
like and alkyl halide or acyl halide is desirably set optimum.
Further, when the polymerization, etherification or esterification
reaction is conducted under an inert gas atmosphere, coloration can
be suppressed.
Polyvinyl Ethers
[0075] In the lubricating oil composition for a compression
refrigerator of the invention, the polyvinyl ethers that can be
used as a base oil contain a polyvinyl compound having a
constituent unit represented by a formula (II)
##STR00004##
[0076] as a main component.
[0077] In the formula (II), R.sup.4, R.sup.5 and R.sup.6
respectively represent a hydrogen atom or a C.sub.1 to C.sub.8
hydrocarbon group, and these may be the same with or different from
each other. Here, specific examples of the hydrocarbon groups
include: alkyl groups such as a methyl group, an ethyl group, an
n-propyl group, an isopropyl group, an n-butyl group, an isobutyl
group, a sec-butyl group, a tert-butyl group, various pentyl
groups, various hexyl groups, various heptyl groups, and various
octyl groups; cycloalkyl groups such as a cyclopentyl group, a
cyclohexyl group, various methyl cyclohexyl groups, various ethyl
cyclohexyl groups, and various dimethyl cyclohexyl groups; aryl
groups such as a phenyl group, various methyl phenyl groups,
various ethyl phenyl groups, and various dimethyl phenyl groups;
and aryl alkyl groups such as a benzyl group, various phenylethyl
groups, and various methyl benzyl groups. These R.sup.4, R.sup.5
and R.sup.6 are particularly preferable to be a hydrogen atom or a
hydrocarbon group having three or less carbon atoms.
[0078] On the other hand, R.sup.7 in the formula (II) represents a
C.sub.2 to C.sub.10 divalent hydrocarbon group. Specific examples
of the C.sub.2 to C.sub.10 divalent hydrocarbon groups include:
divalent aliphatic groups such as an ethylene group, a
phenylethylene group, 1,2-propylene group, a 2-phenyl-1,2-propylene
group, a 1,3-propylene group, various butylene groups, various
pentylene groups, various hexylene groups, various heptylene
groups, various octylene groups, various nonylene groups and
various decylene groups; alicyclic groups having two binding sites
on alicyclic hydrocarbon such as cyclohexane, methylcyclohexane,
ethylcyclohexane, dimethylcyclohexane, and propylcyclohexane;
divalent aromatic hydrocarbon groups such as various phenylene
groups, various methylphenylene groups, various ethylphenylene
groups, various dimethylphenylene groups, and various naphthylenes;
alkyl aromatic groups having a monovalent binding site on each of
an alkyl group moiety and an aromatic moiety of alkyl aromatic
hydrocarbon such as toluene and ethyl benzene; and alkyl aromatic
groups having a binding site on an alkyl group moiety of polyalkyl
aromatic hydrocarbon such as xylene, and diethyl benzene. Among
these, C.sub.2 to C.sub.4 aliphatic groups are particularly
preferred. A plurality of R.sup.7O's may be the same with or
different from each other.
[0079] In the formula (II), p represents the number of repetition,
and an average value thereof is an integer in the range of 0 to 10,
preferably 0 to 5.
[0080] Further, R.sup.8 in the formula (II) represents a C.sub.1 to
C.sub.10 hydrocarbon group. Specific examples of the hydrocarbon
groups include: alkyl groups such as a methyl group, an ethyl
group, an n-propyl group, an isopropyl group, an n-butyl group, an
isobutyl group, a sec-butyl group, a tert-butyl group, various
pentyl groups, various hexyl groups, various heptyl groups, various
octyl groups, various nonyl groups, and various decyl groups;
cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group,
various methylcyclohexyl groups, various ethylcyclohexyl groups,
various propylcyclohexyl groups, and various dimethylcyclohexyl
groups; aryl groups such as a phenyl group, various methyl phenyl
groups, various ethyl phenyl groups, various dimethyl phenyl
groups, various propyl phenyl groups, various trimethyl phenyl
groups, various butyl phenyl groups, and various naphthyl groups;
and aryl alkyl groups such as a benzyl group, various phenylethyl
groups, various methyl benzyl groups, various phenylpropyl groups,
and various phenylbutyl groups. Among these, hydrocarbon groups
having 8 or less carbon atoms are preferred, when p is 0, C.sub.1
to C.sub.6 alkyl groups are preferred, and when p is 1 or more,
C.sub.1 to C.sub.4 alkyl groups are particularly preferred.
[0081] The polyvinyl ether-based compound of the invention can be
manufactured by polymerizing a corresponding vinyl ether monomer.
The vinyl ether monomer that can be used here is represented by a
formula (III)
##STR00005##
[0082] (In the formula, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8
and p are the same as those described above.) As the vinyl ether
monomer, various kinds corresponding to the polyvinyl ether-based
compounds can be cited. Examples thereof include vinyl methyl
ether, vinyl ethyl ether, vinyl-n-propyl ether, vinyl-isopropyl
ether, vinyl-n-butyl ether, vinyl-isobutyl ether, vinyl-sec-butyl
ether, vinyl-tert-butyl ether, vinyl-n-pentyl ether, vinyl-n-hexyl
ether, vinyl-2-methoxyethyl ether, vinyl-2-ethoxyethyl ether,
vinyl-2-methoxy-1-methylethyl ether, vinyl-2-methoxy-propyl ether,
vinyl-3,6-dioxaheptyl ether, vinyl-3,6,9-trioxadecyl ether,
vinyl-1,4-dimethyl-3,6-dioxaheptyl ether,
vinyl-1,4,7-trimethyl-3,6,9-trioxadecyl ether,
vinyl-2,6-dioxa-4-heptyl ether, vinyl-2,6,9-trioxa-4-decyl ether,
1-methoxypropene, 1-ethoxypropene, 1-n-propoxypropene,
1-isopropoxypropene, 1-n-butoxypropene, 1-isobutoxypropene,
1-sec-butoxypropene, 1-tert-butoxypropene, 2-methoxypropene,
2-ethoxypropene, 2-n-propoxypropene, 2-isopropoxypropene,
2-n-butoxypropene, 2-isobutoxypropene, 2-sec-butoxypropene,
2-tert-butoxypropene, 1-methoxy-1-butene, 1-ethoxy-1-butene,
1-n-propoxy-1-butene, 1-isopropoxy-1-butene, 1-n-butoxy-1-butene,
1-isobutoxy-1-butene, 1-sec-butoxy-1-butene,
1-tert-butoxy-1-butene, 2-methoxy-1-butene, 2-ethoxy-1-butene,
2-n-propoxy-1-butene, 2-isopropoxy-1-butene, 2-n-butoxy-1-butene,
2-isobutoxy-1-butene, 2-sec-butoxy-1-butene,
2-tert-butoxy-1-butene, 2-methoxy-2-butene, 2-ethoxy-2-butene,
2-n-propoxy-2-butene, 2-isopropoxy-2-butene, 2-n-butoxy-2-butene,
2-isobutoxy-2-butene, 2-sec-butoxy-2-butene, and
2-tert-butoxy-2-butene. These vinyl ether-based monomers can be
manufactured according to any known methods.
[0083] The terminals of the polyvinyl ether-based compound having
the constitutional unit represented by the formula (II) used as a
main component of the lubricating oil composition for a compression
refrigerator of the invention can be converted to a desired
structure by a method in this application and a known method. As a
group to be converted, a saturated hydrocarbon group, an ether
group, an alcohol group, a ketone group, an amide group, and a
nitrile group can be cited.
[0084] As the polyvinyl ether-based compound that can be used as a
base oil in the lubricating oil composition for a compression
refrigerator of the invention, a compound having the following
terminal structure is suitable. That is, the polyvinyl ether-based
compound has: [0085] (1) a structure in which one of the terminals
is represented by the following general formula (IV),
##STR00006##
[0086] (In the formula, R.sup.9, R.sup.10, and R.sup.11 each
represent a hydrogen atom, or a C.sub.1 to C.sub.8 hydrocarbon
group and may be the same with or different from each other,
R.sup.12 represents a C.sub.2 to C.sub.10 divalent hydrocarbon
group, R.sup.13 represents a C.sub.1 to C.sub.10 hydrocarbon group,
q represents an integer of which an average value is 0 to 10, and
in the case where multiple R.sup.12O's are present, multiple
R.sup.12O's may be the same with or different from each other.),
and the other terminal is represented by the following formula
(V),
##STR00007##
[0087] (In the formula, R.sup.14, R.sup.15, and R.sup.16 each
represent a hydrogen atom, or a C.sub.1 to C.sub.8 hydrocarbon
group and may be the same with or different from each other,
R.sup.17 represents a C.sub.2 to C.sub.10 divalent hydrocarbon
group, R.sup.18 represents a C.sub.1 to C.sub.10 hydrocarbon group,
r represents an integer of which an average value is 0 to 10, and
when multiple R.sup.17O's are present, multiple R.sup.17O's may be
the same with or different from each other.); [0088] (2) a
structure in which one of the terminals is represented by the
formula (IV) and the other terminal is represented by the following
formula (VI),
##STR00008##
[0089] (In the formula, R.sup.19, R.sup.20, and R.sup.21 each
represent a hydrogen atom, or a C.sub.1 to C.sub.8 hydrocarbon
group and may be the same with or different from each other,
R.sup.22 and R.sup.24 each represent a C.sub.2 to C.sub.10 divalent
hydrocarbon group and may be the same with or different from each
other, R.sup.23 and R.sup.25 each represent a C.sub.1 to C.sub.10
hydrocarbon group and may be the same with or different from each
other, s and t each represent such an integer of which an average
value is 0 to 10 and my be the same with or different from each
other, when multiple R.sup.22O's are present, multiple R.sup.22O's
may be the same with or different from each other, and when
multiple R.sup.24O's are present, multiple R.sup.24O's may be the
same with or different from each other); [0090] (3) a structure in
which one of the terminals is represented by the formula (IV) and
the other terminal has an olefinic unsaturated bond; or [0091] (4)
a structure in which one of the terminals is represented by the
formula (IV) and the other terminal is represented by the following
formula (VII),
##STR00009##
[0092] (In the formula, R.sup.26, R.sup.27, and R.sup.28 each
represent a hydrogen atom, or a C.sub.1 to C.sub.8 hydrocarbon
group and may be the same with or different from each other.)
[0093] The polyvinyl ether-based mixture may be a mixture including
two or more kinds of the polyvinyl ether-based compounds selected
from those having the terminal structures described in the (1) to
(4). As such the mixture, for example, a mixture of the compounds
in the (1) and (4) and a mixture of the compounds in the (2) and
(3) can be preferably cited.
[0094] When the polyvinyl ether-based compound is used in
combination with an unsaturated fluorinated hydrocarbon refrigerant
described below, since the refrigerant has an olefinic structure
and is poor in the stability, the hydroxyl group value of a base
oil is preferred to be 17 mgKOH/g or less, more preferred to be 15
mgKOH/g or less, and particularly preferred to be 10 mgKOH/g or
less.
[0095] As the polyvinyl ether-based compound, in order to generate
a polyvinyl ether-based compound having a preferable viscosity
range, the raw material, initiator and reaction condition are
preferably selected. Even a polymer outside the range of kinematic
viscosity, when mixed with a polymer having other kinematic
viscosity, can be adjusted to the viscosity within the range of
kinematic viscosity.
[0096] In the invention, the polyvinyl ether-based compounds may be
used singularly or in a combination of two or more kinds
thereof.
Copolymer of Poly(oxy)alkylene Glycol or Monoether thereof and
Polyvinyl Ether
[0097] It should be noted that the poly(oxy)alkylene glycol refers
to both polyalkylene glycol and polyoxyalkylene glycol.
[0098] In the lubricating oil composition for a compression
refrigerator of the invention, as a copolymer of poly(oxy)alkylene
glycol or a monoether thereof and polyvinyl ether, which can be
used as a base oil, copolymers (Hereinafter, respectively referred
to as polyvinyl ether-based copolymer I and polyvinyl ether-based
copolymer II.) represented by the following formula (VIII) and the
following formula (IX) can be cited.
##STR00010##
[0099] In the formula (VIII), R.sup.29, R.sup.30, and R.sup.31 each
represent a hydrogen atom, or a C.sub.1 to C.sub.8 hydrocarbon
group and may be the same with or different from each other,
R.sup.33 represents a C.sub.2 to C.sub.4 divalent hydrocarbon
group, R.sup.34 represents a C.sub.1 to C.sub.20 aliphatic or
alicyclic hydrocarbon group, a C.sub.1 to C.sub.20 aromatic group
that may have a substituent, a C.sub.2 to C.sub.20 acyl group, or a
C.sub.2 to C.sub.50 oxygen-containing hydrocarbon group, R.sup.32
represents a C.sub.1 to C.sub.10 hydrocarbon group, and when
multiple R.sup.34's, R.sup.33'S, and R.sup.32 s are present,
multiple R.sup.34's, R.sup.33's, and R.sup.32's may be the same
with or different from each other.
[0100] Here, specific examples of the C.sub.1 to C.sub.8
hydrocarbon groups represented by any one of R.sup.29 to R.sup.31
include: alkyl groups such as a methyl group, an ethyl group, an
n-propyl group, an isopropyl group, an n-butyl group, an isobutyl
group, a sec-butyl group, a tert-butyl group, various pentyl
groups, various hexyl groups, various heptyl groups, and various
octyl groups; aryl groups such as a cyclopentyl group, a cyclohexyl
group, various methyl cyclohexyl groups, various ethyl cyclohexyl
groups, various dimethyl cyclohexyl groups, and various dimethyl
phenyl groups; and aryl alkyl groups such as a benzyl group,
various phenyl ethyl groups, and various methyl benzyl groups. It
should be noted that R.sup.29, R.sup.30, and R.sup.31 each
particularly preferably represent a hydrogen atom.
[0101] On the other hand, specific examples of the C.sub.2 to
C.sub.4 divalent hydrocarbon group represented by R.sup.33 include
divalent alkylene groups such as a methylene group, an ethylene
group, a propylene group, a trimethylene group, and various
butylene groups.
[0102] It should be noted that v in the formula (VIII) represents
the number of the repeating of R.sup.330 and an average value
thereof is an integer in the range of 1 to 50, preferably 1 to 20,
more preferably 1 to 10, or particularly preferably 1 to 5. When
multiple R.sup.33O's are present, multiple R.sup.33O's may be the
same with or different from each other.
[0103] In addition, k represents an integer in the range of 1 to
50, preferably 1 to 10, more preferably 1 to 2, or particularly
preferably 1, and u represents an integer in the range of 0 to 50,
preferably 2 to 25, and more preferably 5 to 15. When multiple k's
and u's are present, the polymer may be a block polymer or a random
polymer.
[0104] Further, R.sup.34 in the formula (VIII) preferably
represents a C.sub.1 to C.sub.10 alkyl group, a C.sub.2 to C.sub.10
acyl group, or a C.sub.2 to C.sub.50 oxygen-containing hydrocarbon
group.
[0105] Specific examples of the C.sub.1 to C.sub.10 alkyl groups
include a methyl group, an ethyl group, an n-propyl group, an
isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl
group, a tert-butyl group, various pentyl groups, various hexyl
groups, various heptyl groups, various octyl groups, various nonyl
groups, various decyl groups, a cyclopentyl group, a cyclohexyl
group, various methyl cyclohexyl groups, various ethyl cyclohexyl
groups, various propyl cyclohexyl groups, and various dimethyl
cyclohexyl groups.
[0106] In addition, as the C.sub.2 to C.sub.10 acyl group, an
acetyl group, a propionyl group, a butyryl group, an isobutyryl
group, a valeryl group, an isovaleryl group, a pivaloyl group, a
benzoyl group, and a toluoyl group can be cited.
[0107] Further, specific examples of the C.sub.2 to C.sub.50
oxygen-containing hydrocarbon groups preferably include a
methoxymethyl group, a methoxyethyl group, a methoxypropyl group, a
1,1-bismethoxypropyl group, a 1,2-bismethoxypropyl group, an
ethoxypropyl group, a (2-methoxyethoxy)propyl group, and a
(1-methyl-2-methoxy)propyl group.
[0108] In the formula (VIII), specific examples of the C.sub.1 to
C.sub.10 hydrocarbon groups represented by R.sup.32 include: alkyl
groups such as a methyl group, an ethyl group, an n-propyl group,
an isopropyl group, an n-butyl group, an isobutyl group, various
pentyl groups, various hexyl groups, various heptyl groups, various
octyl groups, various nonyl groups, and various decyl groups;
cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group,
various methylcyclohexyl groups, various ethylcyclohexyl groups,
various propylcyclohexyl groups, and various dimethylcyclohexyl
groups; aryl groups such as a phenyl group, various methyl phenyl
groups, various ethyl phenyl groups, various dimethyl phenyl
groups, various propyl phenyl groups, various trimethyl phenyl
groups, various butyl phenyl groups, and various naphthyl groups;
and aryl alkyl groups such as a benzyl group, various phenylethyl
groups, various methylbenzyl groups, various phenylpropyl groups,
and various phenylbutyl groups.
[0109] It should be noted that R.sup.29 to R.sup.31, R.sup.34,
R.sup.33, and v, and R.sup.29 to R.sup.32 may be the same with or
different from each other among constitutional units.
[0110] The polyvinyl ether-based copolymer I having the
constitutional unit represented by the formula (VIII) has an effect
of improving the lubricity, insulating property, and hygroscopic
property while satisfying the compatibility by forming into a
copolymer. In this case, the properties of the lubricant can be
adjusted to the intended level by selecting the kind of the monomer
as a raw material, the kind of the initiator, and the rate of the
copolymer. Therefore, the polyvinyl ether-based copolymer I has an
effect that a lubricant according to requirements of the type of a
compressor in a refrigerating system or a conditioner system, and
the lubricity, the compatibility, and the like, which are different
according to the material of a lubricating part, refrigerating
capacity, the kind of the refrigerant, and the like, can be
obtained freely.
[0111] On the other hand, in the polyvinyl ether-based copolymer II
represented by the formula (IX), R.sup.29 to R.sup.32, R.sup.33,
and v each have the same meaning as that described above. When
multiple R.sup.33's and R.sup.32's are present, each of R.sup.33's
and R.sup.32's may be the same with or different from each other. x
and y each represent an integer of 1 to 50. When multiple x's and
y's are present, the copolymer may have a block polymer structure
or a random polymer structure. X and Y each independently represent
a hydrogen atom, a hydroxyl group, or a C.sub.1 to C.sub.20
hydrocarbon group.
[0112] A manufacturing method of the polyvinyl ether-based
copolymer I represented by the formula (VIII) is not particularly
limited as long as the polyvinyl ether-based copolymer I can be
obtained. For example, the polyvinyl ether-based copolymer I can be
manufactured by the following manufacturing methods 1 to 3.
Manufacturing Method 1 of Polyvinyl Ether-Based Copolymer I
[0113] In the manufacturing method 1, a poly(oxy)alkylene glycol
compound represented by the following formula (X),
R.sup.34--(OR.sup.33).sub.v--OH (X)
(In the formula, R.sup.33 and R.sup.34, and v each have the same
meaning as that described above.) is used as an initiator, and a
vinyl ether-based compound represented by the following formula
(XI),
##STR00011##
[0114] (In the formula, R.sup.29 to R.sup.32 each have the same
meaning as that described above.), is polymerized, whereby the
polyvinyl ether-based copolymer I can be obtained.
[0115] Examples of poly(oxy)alkylene glycol compounds represented
by the formula (X) include (oxy)alkylene glycol monoethers such as
ethylene glycol monomethyl ether, diethylene glycol monomethyl
ether, triethylene glycol monomethyl ether, propylene glycol
monomethyl ether, dipropylene glycol monomethyl ether, and
tripropylene glycol monomethyl ether.
[0116] Further, examples of the vinyl ether-based compounds
represented by the formula (XI) include: vinyl ethers such as vinyl
methyl ether, vinyl ethyl ether, vinyl-n-propyl ether,
vinyl-isopropyl ether, vinyl-n-butyl ether, vinyl-isobutyl ether,
vinyl-sec-butyl ether, vinyl-tert-butyl ether, vinyl-n-pentyl
ether, and vinyl-n-hexyl ether; propenes such as 1-methoxypropene,
1-ethoxypropene, 1-n-propoxypropene, 1-isopropoxypropene,
1-n-butoxypropene, 1-isobutoxypropene, 1-sec-butoxypropene,
1-tert-butoxypropene, 2-methoxypropene, 2-ethoxypropene,
2-n-propoxypropene, 2-isopropoxypropene, 2-n-butoxypropene,
2-isobutoxypropene, 2-sec-butoxypropene, and 2-tert-butoxypropene;
and butenes such as 1-methoxy-1-butene, 1-ethoxy-1-butene,
1-n-propoxy-1-butene, 1-isopropoxy-1-butene, 1-n-butoxy-1-butene,
1-isobutoxy-1-butene, 1-sec-butoxy-1-butene,
1-tert-butoxy-1-butene, 2-methoxy-1-butene, 2-ethoxy-1-butene,
2-n-propoxy-1-butene, 2-isopropoxy-1-butene, 2-n-butoxy-1-butene,
2-isobutoxy-1-butene, 2-sec-butoxy-1-butene,
2-tert-butoxy-1-butene, 2-methoxy-2-butene, 2-ethoxy-2-butene,
2-n-propoxy-2-butene, 2-isopropoxy-2-butene, 2-n-butoxy-2-butene,
and 2-tert-butoxy-2-butene. These vinyl ether-based monomers can be
manufactured by any known methods.
Manufacturing Method 2 of Polyvinyl Ether-Based Copolymer I
[0117] In the manufacturing method 2, an acetal compound
represented by the following formula (XII),
##STR00012##
[0118] (In the formula, R.sup.29 to R.sup.34, and v each have the
same meaning as that described above.) is used as an initiator, and
the vinyl ether-based compound represented by the formula (XI) is
polymerized, whereby the polyvinyl ether-based copolymer I can be
obtained.
[0119] Examples of the acetal compounds represented by the formula
(XII) include acetaldehyde methyl(2-methoxyethyl)acetal,
acetaldehyde ethyl(2-methoxyethyl)acetal, acetaldehyde
methyl(2-methoxy-1-methylethyl) acetal, acetaldehyde
ethyl(2-methoxy-1-methylethyl)acetal, acetaldehyde
methyl[2-(2-methoxyethoxy)ethyl]acetal, acetaldehyde
ethyl[2-(2-methoxyethoxy)ethyl]acetal, acetaldehyde
methyl[2-(2-methoxyethoxy)-1-methylethyl]acetal, and acetaldehyde
ethyl[2-(2-methoxyethoxy)-1-methylethyl]acetal.
[0120] In addition, the acetal compound represented by the formula
(XII) can be manufactured by reacting one molecule of the
poly(oxy)alkylene glycol compound represented by the formula (X)
with one molecule of the vinyl ether-based compound represented by
the formula (XI). The obtained acetal compound is used as an
initiator after being isolated or as it is.
Manufacturing Method 3 of Polyvinyl Ether-Based Copolymer I
[0121] In the manufacturing method 3, an acetal compound
represented by the following formula (XIII),
##STR00013##
[0122] (In the formula, R.sup.29 to R.sup.31, R.sup.33, R.sup.34
and v have the same meaning as that described above.) is used as an
initiator, and the vinyl ether-based compound represented by the
formula (XI) is polymerized, whereby a polyvinyl ether-based
copolymer I can be obtained.
[0123] Examples of the acetal compounds represented by the formula
(XIII) include acetaldehyde di(2-methoxyethyl)acetal, acetaldehyde
di(2-methoxy-1-methylethyl)acetal, acetaldehyde
di[2-(2-methoxyethoxy)ethyl]acetal, and acetaldehyde
di[2-(2-methoxyethoxy)-1-methylethyl]acetal.
[0124] In addition, the acetal compound represented by the formula
(XIII) can be also manufactured by reacting one molecule of the
poly(oxy)alkylene glycol compound represented by the formula (X)
with one molecule of a vinyl ether-based compound represented by
the following formula (XIV),
##STR00014##
[0125] (In the formula, R.sup.29 to R.sup.31, R.sup.33, R.sup.34
and v have the same meaning as that described above.). The obtained
acetal compound may be used as an initiator after being isolated or
as it is.
[0126] The vinyl ether-based copolymer I represented by the formula
(VIII) can be formed into a vinyl ether-based copolymer I having a
structure in which one of the terminals is represented by the
following formula (XV) or (XVI),
##STR00015##
[0127] (In the formula, R.sup.29 to R.sup.34 and v have the same
meaning as that described above.), and the other terminal thereof
is represented by the following formula (XVII) or (XVIII),
##STR00016##
[0128] (In the formula, R.sup.29 to R.sup.34 and v have the same
meaning as that described above.).
[0129] Of these polyvinyl ether-based copolymers I, the followings
are particularly suitable for the base oil in a lubricating oil
composition for a compression refrigerator of the invention. [0130]
(1) A substance having a structure in which one of the terminals is
represented by the formula (XV) or (XVI), and the other terminal is
represented by the formula (XVII) or (XVIII), and in the formula
(VIII), R.sup.29, R.sup.30, and R.sup.31 each represent a hydrogen
atom, v represents an integer in the range of 1 to 4, R.sup.33
represents a C.sub.2 to C.sub.4 divalent hydrocarbon group,
R.sup.34 represents a C.sub.1 to C.sub.10 alkyl group, and R.sup.32
represents a C.sub.1 to C.sub.10 hydrocarbon group. [0131] (2) A
substance having a structure in which one of the terminals is
represented by the formula (XV), and the other terminal is
represented by the formula (XVIII), and in the formula (VIII),
R.sup.29, R.sup.30, and R.sup.31 each represent a hydrogen atom, v
represents an integer in the range of 1 to 4, R.sup.33 represents a
C.sub.2 to C.sub.4 divalent hydrocarbon group, R.sup.34 represents
a C.sub.1 to C.sub.10 alkyl group, and R.sup.32 represents a
C.sub.1 to C.sub.10 hydrocarbon group. [0132] (3) A substance
having a structure in which one of the terminals is represented by
the formula (XVI), and the other terminal is represented by the
formula (XVII), and in the formula (VIII), R.sup.29, R.sup.30, and
R.sup.31 each represent a hydrogen atom, v represents an integer in
the range of 1 to 4, R.sup.33 represents a C.sub.2 to C.sub.4
divalent hydrocarbon group, R.sup.34 represents a C.sub.1 to
C.sub.10 alkyl group, and R.sup.32 represents a C.sub.1 to C.sub.10
hydrocarbon group.
[0133] On the other hand, a manufacturing method of the polyvinyl
ether-based copolymer II represented by the formula (IX) is not
particularly limited as long as the polyvinyl ether-based copolymer
II can be obtained, and the polyvinyl ether-based copolymer II can
be manufactured efficiently by the following method.
Manufacturing Method of Polyvinyl Ether-Based Copolymer II
[0134] The polyvinyl ether-based copolymer II represented by the
formula (IX) can be obtained by using poly(oxy)alkylene glycol
represented by the following formula (XIX)
HO--(R.sup.33O).sub.v--H (XIX)
(In the formula, R.sup.33 and v each have the same meaning as that
described above.) as an initiator, and by polymerizing the vinyl
ether compound represented by the formula (XI).
[0135] Examples of the poly(oxy)alkylene glycol represented by the
formula (XIX) include ethylene glycol, diethylene glycol,
triethylene glycol, polyethylene glycol, propylene glycol,
dipropylene glycol, and polypropylene glycol.
[0136] When the polyvinyl ether-based compound is used in
combination with an unsaturated fluorinated hydrocarbon refrigerant
described below, since the refrigerant has an olefinic structure
and is poor in the stability, the hydroxyl group value of a base
oil is preferred to be 15 mgKOH/g or less.
[0137] In the present invention, the copolymers of the poly(oxy)
alkylene glycols or monoether thereof and polyvinyl ethers may be
used singularly or in a combination of two or more kinds
thereof.
Polyol Esters
[0138] In the lubricating oil composition for a compression
refrigerator of the invention, as the polyol esters to be used as
the base oil, esters of a diol or a polyol having about 3 to 20
hydroxyl groups and an aliphatic acid having about 1 to 24 carbon
atoms are preferably used.
[0139] Here, examples of the diols include ethylene glycol,
1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol,
2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol,
1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol,
2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol,
1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol,
and 1,12-dodecanediol.
[0140] Examples of the polyols include: polyhydric alcohols such as
trimethylolethane, trimethylolpropane, trimethylolbutane,
di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol,
di-(pentaerythritol), tri-(pentaerythritol), glycerin, polyglycerin
(dimer to 20-mer of glycerin), 1,3,5-pentanetriol, sorbitol,
sorbitan, a sorbitol glycerin condensate, adonitol, arabitol,
xylitol, and mannitol; saccharides suchasxylose, arabinose, ribose,
rhamnose, glucose, fructose, galactose, mannose, sorbose,
cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose,
gentianose, and merenditose; and partially etherified products and
methyl glucosides(glucosides). Of these, a hindered alcohol such as
neopentyl glycol, trimethylolethane, trimethylolpropane,
trimethylolbutane, di-(trimethylolpropane),
tri-(trimethylolpropane), pentaerythritol, di-(pentaerythritol), or
tri-(pentaerythritol) is preferred as a polyol.
[0141] The aliphatic acid may have any number of carbon atoms
without any particular limitation; a C.sub.1 to C.sub.24 aliphatic
acid is typically used. Of the C.sub.1 to C.sub.24 aliphatic acids,
an aliphatic acid having 3 or more carbon atoms is preferred, an
aliphatic acid having 4 or more carbon atoms is more preferred, an
aliphatic acid having 5 or more carbon atoms is still more
preferred, and an aliphatic acid having 10 or more carbon atoms is
most preferred in terms of lubricity. In addition, an aliphatic
acid having 18 or less carbon atoms is preferred, an aliphatic acid
having 12 or less carbon atoms is more preferred, and an aliphatic
acid having 9 or less carbon atoms is still more preferred in terms
of compatibility with the refrigerant.
[0142] In addition, the aliphatic acid may be a straight chained
aliphatic acid or a branched aliphatic acid; the aliphatic acid is
preferably a straight chained aliphatic acid in terms of lubricity,
or is preferably a branched aliphatic acid in terms of hydrolytic
stability. Further, the aliphatic acid may be a saturated aliphatic
acid or an unsaturated aliphatic acid.
[0143] Specific examples of the aliphatic acids include: straight
chained or branched pentanoic acid, hexanoic acid, heptanoic acid,
octanoic acid, nonanoic acid, decanoic acid, undecanoic acid,
dodecanoic acid, tridecanoic acid, tetradecanoic acid,
pentadecanoic acid, hexadecanoic acid, heptadecanoic acid,
octadecanoic acid, nonadecanoic acid, icosanoic acid, and oleic
acid; or a neoic acid of which the .alpha.-carbon atom is
quaternary. More specifically, valeric(n-pentanoic) acid,
caproic(n-hexanoic) acid, enanthic(n-heptanoic) acid,
caprylic(n-octanoic) acid, pelargonic(n-nonanoic) acid,
capric(n-decanoic) acid, oleic(cis-9-octadecenoic) acid,
isopentanoic(3-methylbutanoic) acid, 2-methylhexanoic acid,
2-ethylpentanoic acid, 2-ethylhexanoic acid, and
3,5,5-trimethylhexanoic acid are preferred.
[0144] It should be noted that the polyol ester may be a partial
ester in which some of the hydroxyl groups of a polyol remain
without being esterified, may be a complete ester in which all of
the hydroxyl groups of the polyol are esterified, or may be a
mixture of a partial ester and a complete ester; the polyol ester
is preferably a complete ester.
[0145] Of the polyol esters, an ester of a hindered alcohol such as
neopentyl glycol, trimethylolethane, trimethylolpropane,
trimethylolbutane, di-(trimethylolpropane),
tri-(trimethylolpropane), pentaerythritol, di-(pentaerythritol), or
tri-(pentaerythritol) is more preferred, and an ester of neopentyl
glycol, trimethylolethane, trimethylolpropane, trimethylolbutane,
or pentaerythritol is still more preferred because such ester is
additionally excellent in hydrolytic stability. An ester of
pentaerythritol is most preferred because the ester is particularly
excellent in compatibility with the refrigerant and hydrolytic
stability.
[0146] Specific examples of the preferred polyol esters include: a
diester formed of neopentyl glycol and one kind or two or more
kinds of aliphatic acids selected from valeric acid, caproic acid,
enanthic acid, caprylic acid, pelargoic acid, capric acid, oleic
acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; a
triester formed of trimethylol ethane and one kind or two or more
kinds of aliphatic acids selected from valeric acid, caproic acid,
enanthic acid, caprylic acid, pelargoic acid, capric acid, oleic
acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; a
triester formed of trimethylol propane and one kind or two or more
kinds of aliphatic acids selected from valeric acid, caproic acid,
enanthic acid, caprylic acid, pelargoic acid, capric acid, oleic
acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; a
triester formed of trimethylol butane and one kind or two or more
kinds of aliphatic acids selected from valeric acid, caproic acid,
enanthic acid, caprylic acid, pelargoic acid, capric acid, oleic
acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; and a
tetraester formed of pentaerythritol and one kind or two or more
kinds of aliphatic acids selected from valeric acid, caproic acid,
enanthic acid, caprylic acid, pelargoic acid, capric acid, oleic
acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid.
[0147] It should be noted that the esters with two or more kinds of
aliphatic acids may be a mixture of two or more kinds of esters
formed of one kind of aliphatic acid and a polyol. An ester formed
of two or more kinds of mixed aliphatic acids and a polyol,
particularly an ester formed of mixed aliphatic acids and a polyol
is excellent in low temperature properties and compatibility with a
refrigerant.
[0148] When the polyol ester is used together with an unsaturated
fluorinated hydrocarbon refrigerant described below, the
refrigerant has an olefin structure and is poor in the stability.
Accordingly, the base oil preferably has an acid value of 0.02
mgKOH/g or less and a hydroxyl group value of 5 mgKOH/g or less.
The acid value is more preferably 0.01 mgKOH/g or less, and the
hydroxyl group value is more preferably 3 mgKOH/g or less.
[0149] It is also preferred that the base oil has an ASTM color of
1 or less, a surface tension of 20 mN/m or more, a pH of extracted
water of 5.5 or more, an ash content of 0.1% by mass or less, and a
volume resistivity of 10.sup.9 .OMEGA.m or more. The base oil
having characteristics like this is preferred because the stability
is excellent and electric insulating property is excellent.
[0150] When the polyol ester-based compound is manufactured by
esterifying under an inert gas atmosphere, the compound can be
prevented from being colored. Further, in a ratio of polyhydric
alcohol and aliphatic monocarboxylic acid, which are reacted, when
an amount of aliphatic monocarboxylic acid is stoichiometrically
less contained, hydroxyl groups partially remain to raise the
hydroxyl group value, on the other hand, when an amount of
aliphatic monocarboxylic acid is stoichiometrically much contained,
carboxylic acid partially remains to raise the acid value and
reduce the pH of the extracted water. Accordingly, it is desirable
that a molar ratio of polyhydric alcohol and aliphatic
monocarboxylic acid is optimized, and, an amount of the remaining
esterification catalyst (ash content) is made as small as
possible.
Polycarbonates
[0151] As the polycarbonates which can be used as the base oil in
the lubricating oil composition for a compression refrigerator of
the invention, at least one kind selected from polycarbonates each
having two or more carbonate bonds in one molecule, that is:
compounds each represented by the following formula (XX),
##STR00017##
[0152] (In the formula, Z represents a residue obtained by removing
a hydroxyl group from a C.sub.1 to C.sub.12 e-valent alcohol;
R.sup.35 represents a C.sub.2 to C.sub.10 straight chained or
branched alkylene group; R.sup.36 represents a C.sub.1 to C.sub.12
monovalent hydrocarbon group or a group containing an ether bond
represented by R.sup.38(O--R.sup.37).sub.f- (where R.sup.38
represents a hydrogen atom or a C.sub.1 to C.sub.12 monovalent
hydrocarbon group, R.sup.37 represents a C.sub.2 to C.sub.10
straight chained or branched alkylene group, and f represents an
integer of 1 to 20.); c represents an integer of 1 to 30, d
represents an integer of 1 to 50; and e represents an integer of 1
to 6.); and compounds each represented by the following general
formula (XXI),
##STR00018##
[0153] (In the formula, R.sup.39 represents a C.sub.2 to C.sub.10
straight chained or branched alkylene group; g represents an
integer of 1 to 20; and Z, R.sup.39, R.sup.36, c, d, and e each
have the same meaning as that described above.) can be preferably
cited.
[0154] In each of the formulas (XX) and (XXI), Z, which represents
a residue obtained by removing a hydroxyl group from a C.sub.1 to
C.sub.12 monovalent to hexavalent alcohol, particularly preferably
represents a residue obtained by removing a hydroxyl group from a
C.sub.1 to C.sub.12 monovalent alcohol.
[0155] Among C.sub.1 to C.sub.12 monovalent to hexavalent alcohols
having the residue represented by Z include, examples of the
monovalent alcohols include: aliphatic monovalent alcohols such as
methyl alcohol, ethyl alcohol, n- or isopropyl alcohol, various
butyl alcohols, various pentyl alcohols, various hexyl alcohols,
various octyl alcohols, various decyl alcohols, and various dodecyl
alcohols; alicyclic monovalent alcohols such as cyclopentyl alcohol
and cyclohexyl alcohol; aromatic alcohols such as phenol, cresol,
xylenol, butyl phenol, and naphthol; and aromatic aliphatic
alcohols such as benzyl alcohol and phenethyl alcohol; examples of
the bivalent alcohols include: aliphatic alcohols such as ethylene
glycol, propylene glycol, butylene glycol, neopentylene glycol, and
tetramethylene glycol; alicyclic alcohols such as cyclohexanediol
and cyclohexanedimethanol; and aromatic alcohols such as catechol,
resorcinol, hydroquinone, and dihydroxy diphenyl; examples of
trivalent alcohols include: aliphatic alcohols such as glycerin,
trimethylol propane, trimethylol ethane, trimethylol butane, and
1,3,5-pentanetriol; alicyclic alcohols such as cyclohexanetriol and
cyclohexanetrimethanol; and aromatic alcohols such as pyrogallol
and methylpyrogallol; and examples of tetravalent to hexavalent
alcohols include aliphatic alcohols such as pentaerythritol,
diglycerin, triglycerin, sorbitol, and dipentaerythritol.
[0156] As such the polycarbonate compounds, as compounds
represented by the following formula (XX), compounds represented by
a formula (XX-a)
##STR00019##
[0157] (In the formula, R.sup.40 represents a residue obtained by
removing a hydroxyl group from a C.sub.1 to C.sub.12 monovalent
alcohol, and R.sup.35, R.sup.36, c, and d each have the same
meaning as that described above.), and/or, as compounds represented
by a formula (XXI), compounds represented by the following formula
(XXI-a),
##STR00020##
[0158] (In the formula, R.sup.35, R.sup.36, R.sup.39, R.sup.48, c,
d and g each have the same meaning as that described above.) can be
cited.
[0159] Examples of the residues obtained by removing a hydroxyl
group from a C.sub.1 to C.sub.12 monovalent alcohol represented by
R.sup.40 in each of the formulae (XX-a) and (XXI-a) include:
aliphatic hydrocarbon groups such as a methyl group, an ethyl
group, an n-propyl group, an isopropyl group, various butyl groups,
various pentyl groups, various hexyl groups, various octyl groups,
various decyl groups, and various dodecyl groups; alicyclic
hydrocarbon groups such as a cyclopentyl group, a cyclohexyl group,
a methylcyclohexyl group, a dimethylcyclohexyl group, and a
decahydronaphthyl group; aromatic hydrocarbon groups such as a
phenyl group, various tolyl groups, various xylyl groups, a mesityl
group, and various naphthyl groups; and aromatic aliphatic
hydrocarbon groups such as a benzyl group, a methylbenzyl group, a
phenethyl group, and various naphthylmethyl groups. Of these, a
C.sub.1 to C.sub.6 straight chained or branched alkyl group is
preferable.
[0160] R.sup.35, which represents a C.sub.2 to C.sub.10 straight
chained or branched alkylene group, preferably represents a C.sub.2
to C.sub.6 straight chained or branched alkylene group, and
particularly preferably represents an ethylene group or a propylene
group in terms of, for example, the performance of the compound and
the ease with which the compound is produced. Further, R.sup.36
represents a C.sub.1 to C.sub.12 monovalent hydrocarbon group or a
group containing an ether bond represented by R.sup.38 (O-13
R.sup.37).sub.f- (where R.sup.38 represents a hydrogen atom or a
C.sub.1 to C.sub.12 or preferably C.sub.1 to C.sub.6 monovalent
hydrocarbon group, R.sup.37 represents a C.sub.2 to C.sub.10
straight chained or branched alkylene group, and f represents an
integer of 1 to 20), and examples of the above C.sub.1 to C.sub.12
monovalent hydrocarbon groups include examples similar to those
described in the description of the R.sup.40. In addition, a
C.sub.2 to C.sub.10 straight chained or branched alkylene group
represented by R.sup.37 is preferably a C.sub.2 to C.sub.6 straight
chained or branched alkylene group, or is particularly preferably
an ethylene group and a propylene group by the same reason as that
in the case of the R.sup.35.
[0161] R.sup.36 particularly preferably represents a C.sub.1 to
C.sub.6 straight chained or branched alkyl group.
[0162] In the formula (XXI-a), a C.sub.2 to C.sub.10 straight
chained or branched alkylene group represented by R.sup.39 is
preferably a C.sub.2 to C.sub.6 alkylene group, particularly, an
ethylene group and a propylene group, in terms of the same reason
as that described in the case of the R.sup.35.
[0163] Such the polycarbonate compound can be manufactured by any
one of various methods; a target polycarbonate compound can be
manufactured by causing a carbonate-formable derivative such as a
carbonic acid diester or phosgene and an alkylene glycol or a
polyalkylene glycol to react with each other in accordance with a
known method.
[0164] In the present invention, the polycarbonates may be used
singularly or in a combination of two or more kinds thereof.
[0165] In the lubricating oil composition for a compression
refrigerator of the invention, as a base oil, a substance
including, as a main component, at least one kind of
oxygen-containing compound selected from the polyoxyalkylene
glycols, polyvinyl ethers, copolymers of poly(oxy)alkylene glycol
or monoether thereof and polyvinyl ether, polyol esters, and
polycarbonates is preferably used. Here, the phrase "including as a
main component" refers to including the oxygen-containing compound
at a rate of 50% by mass or more. The content of the
oxygen-containing compound 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.
[0166] In the invention, the kinematic viscosity of the base oil at
100.degree. C. is preferably 1 mm.sup.2/s or more and 50 mm.sup.2/s
or less, more preferably 3 mm.sup.2/s or more and 40 mm.sup.2/s or
less, and still more preferably 4 mm.sup.2/s or more and 30
mm.sup.2/s or less. When the kinematic viscosity is 1 mm.sup.2/s or
more, favorable lubricity (load capacity resistance) is exhibited
and sealing property is good, and when the kinematic viscosity is
50 mm.sup.2/s or less, energy saving is also favorable.
[0167] In addition, the number average molecular weight of the base
oil is preferably 300 or more and 3000 or less, more preferably 500
or more and 3,000 or less, and still more preferably 700 or more
and 2,500 or less. The flashing point of the base oil is preferably
150.degree. C. or higher. When the number average molecular weight
of the base oil is 300 or more and 3000 or less, desirable
performance as the refrigerator oil can be exhibited and the
flashing point of the base oil can be set within the range.
[0168] In addition, the viscosity index of the base oil of the
invention is preferably 60 or more and more preferably 80 or more.
However, the upper limit of the viscosity index is about 300 in
terms of restriction on manufacture.
[0169] When the viscosity index is set to 60 or more, the kinematic
viscosity at a high temperature can be prevented from becoming
lower.
[0170] The viscosity index of the base oil can be measured
according to JIS K 2283.
[0171] In the invention, when the base oil has the above
properties, the lubricating oil composition may include, in
addition to the oxygen-containing compound, another base oil at 50%
by mass or less, preferably 30% by mass or less, and more
preferably 10% by mass or less, and the lubricating oil composition
free of another base oil is still more preferred.
[0172] As the base oil that can be used together with the
oxygen-containing compound, other polyesters, a hydrogenation
product of .alpha.-olefin oligomer, a mineral oil, an alicyclic
hydrocarbon compound, an alkylated aromatic hydrocarbon compound
are exemplified.
Refrigerant
[0173] As the refrigerant to which the lubricating oil composition
for a compression refrigerator of the invention is applied, a
refrigerant containing a C.sub.1 to C.sub.3, preferably, C.sub.1 to
C.sub.2 saturated fluorinated hydrocarbon compound (HFC) is
used.
[0174] Preferable examples of the C.sub.1 to C.sub.3 saturated
fluorinated hydrocarbon compounds include trifluoromethane,
difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane,
1,1,2-trifluoroethane, 1,1,1,2-tetrafluoroethane,
1,1,2,2-tetrafluoroethane, 1,1,1,2,2-pentafluoroethane, and
1,1,1,3,3-pentafluoropropane.
[0175] These refrigerants may be used singularly or in a
combination of two or more kinds thereof.
[0176] When difluoromethane (R32), for example, is used as the
saturated fluorinated hydrocarbon, the R32 can be preferably used
singularly. However, the R32 may be mixed with
1,1,1,2,2-pentafluoroethane (R125), or may be mixed with R125 and
1,1,1,2-tetrafluoroethane (R134a). Examples of the former include
R410A, and examples of the latter include R407C.
[0177] When a mixture of the R32 and other C.sub.1 to C.sub.3
saturated fluorinated hydrocarbon compound is used, a ratio of the
R32 in an entire refrigerant is preferably 20% by mass or more,
more preferably 40% by mass or more, and still more preferably 70%
by mass or more.
[0178] In addition, the C.sub.1 to C.sub.3 saturated fluorinated
hydrocarbon compound may be used by mixing with a refrigerant other
than the C.sub.1 to C.sub.3 saturated fluorinated hydrocarbon
compound. In this case, a mixing ratio of the refrigerant other
than the C.sub.1 to C.sub.3 saturated fluorinated hydrocarbon
compound is preferably 30% by mass or less and more preferably 20%
by mass or less of an entire refrigerant.
[0179] As the refrigerant other than the C.sub.1 to C.sub.3
saturated fluorinated hydrocarbon compound, carbon dioxide
(CO.sub.2), low boiling hydrocarbon (HC), ammonia, or at least one
kind of fluorine-containing organic compound selected from
compounds represented by the following molecular formula (A) can be
cited.
C.sub.pO.sub.qF.sub.rR.sub.s (A)
(In the formula, R represents Cl, Br, I or H, p is an integer of 1
to 6, q is an integer of 0 to 2, r is an integer of 1 to 14, and s
is an integer of 0 to 13. However, when q is 0, p is an integer of
2 to 6, and one or more carbon-carbon unsaturated bonds are present
in one molecule.)
[0180] Hereinafter, the refrigerants represented by the molecular
formula (A) will be detailed.
[0181] The molecular formula (A), which shows the types and the
numbers of elements in the molecule, represents fluorine-containing
organic compounds where the number p of carbon atoms C is in the
range of 1 to 6. The fluorine-containing organic compound having 1
to 6 carbon atoms can have physical and chemical properties such as
a boiling point, a freezing point, an evaporative latent heat,
which are required for the refrigerant.
[0182] In the molecular formula (A), a bonding state of p carbon
atoms represented by C.sub.p includes unsaturated bonds such as a
carbon-carbon single bond and a carbon-carbon double bond, and a
carbon-oxygen double bond. In terms of the stability, the
carbon-carbon unsaturated bond is preferable to be a carbon-carbon
double bond, and the number thereof, which is typically one or
more, is preferred to be one.
[0183] In the formula (A), the bond state of q oxygen atoms
represented by O.sub.q preferably is oxygen from an ether group, a
hydroxyl group, or a carbonyl group. The number of oxygen atoms q
may be two, which includes cases in which two ether groups,
hydroxyl groups or the like are provided.
[0184] In addition, when q in O.sub.q is zero, which means that the
molecule does not include oxygen atoms, p falls in the range of 2
to 6, which means that the molecule includes one or more
unsaturated bonds such as carbon-carbon double bonds in one
molecule. In other words, at least one of the bond states of p
carbon atoms represented by C.sub.p needs to be a carbon-carbon
unsaturated bond.
[0185] Besides, in the formula (A), R represents Cl, Br, I, or H,
any of which may be selected. However, R preferably is Hon account
of less possibility of destroying the ozone layer.
[0186] As set forth above, preferable examples of the
fluorine-containing organic compounds represented by the molecular
formula (A) include an unsaturated fluorinated hydrocarbon
compound, a fluorinated ether compound, a fluorinated alcohol
compound, and a fluorinated ketone compound.
[0187] Hereinafter, these compounds will be described.
Unsaturated Fluorinated Hydrocarbon Compound
[0188] According to the invention, an example of an unsaturated
fluorinated hydrocarbon compound that can be used as a freezer
refrigerant, an unsaturated fluorinated hydrocarbon compound
represented by, for example, the molecular formula (A) in which R
is H, p is an integer of 2 to 6, q is 0, r is an integer of 1 to
12, and s is an integer of 0 to 11 can be cited.
[0189] Preferred examples of such unsaturated fluorinated
hydrocarbon compounds include C.sub.2 to C.sub.6 linear-chain or
branched chain olefins and fluorides of C.sub.4 to C.sub.6 ring
olefins.
[0190] The specific examples thereof include ethylene to which 1 to
3 fluorine atoms are introduced, propene to which 1 to 5 fluorine
atoms are introduced, butenes to which 1 to 7 fluorine atoms are
introduced, pentenes to which 1 to 9 fluorine atoms are introduced,
hexenes to which 1 to 11 fluorine atoms are introduced, cyclobutene
to which 1 to 5 fluorine atoms are introduced, cyclopentene to
which 1 to 7 fluorine atoms are introduced, and cyclohexene to
which 1 to 9 fluorine atoms are introduced.
[0191] Among the above unsaturated fluorinated hydrocarbon
compounds, C.sub.2 to C.sub.3 unsaturated fluorinated hydrocarbon
compounds are preferred, that is, fluorinated compounds of ethylene
such as trifluoroethylene and fluorinated compounds of various
propene can be cited, in particular, fluorinated compounds of
propene are further preferred. Examples of fluorinated compounds of
propene include 3,3,3-trifluoropropene, 1,3,3,3-tetrafluoropropene
and 2,3,3,3-tetrafluoropropene. In particular, in terms of low
global warming potential, 1,2,3,3,3-pentafluoropropene (HFO1225ye),
1,3,3,3-tetrafluoropropene (HFO1234ze) and
2,3,3,3-tetrafluoropropene (HFO1234yf) are preferred.
[0192] In the invention, the unsaturated fluorinated hydrocarbon
compounds may be used singularly or in a combination of two or more
kinds thereof.
Fluorinated Ether Compound
[0193] According to the invention, an example of a fluorinated
ether compound that can be used as a freezer refrigerant, a
fluorinated ether compound represented by, for example, the
molecular formula (A), in which R is H, p is an integer of 2 to 6,
q is an integer of 1 or 2, r is an integer of 1 to 14, and s is an
integer of 0 to 13 can be cited.
[0194] Preferable examples of such fluorinated ether compounds
include: fluorinated compounds of chained aliphatic ether having 2
to 6 carbon atoms and 1 or 2 ether bonds, in which the alkyl group
is straight chained or branched; and fluorinated compounds of ring
aliphatic ether having 3 to 6 carbon atoms and 1 or 2 ether
bonds.
[0195] The specific examples thereof include fluorinated dimethyl
ethers to which 1 to 6 fluorine atoms are introduced, fluorinated
methylethyl ethers to which 1 to 8 fluorine atoms are introduced,
fluorinated dimethoxymethanes to which 1 to 8 fluorine atoms are
introduced, fluorinated methylpropyl ethers to which 1 to 10
fluorine atoms are introduced, fluorinated methylbutyl ethers to
which 1 to 12 fluorine atoms are introduced, fluorinated ethyl
propyl ethers to which 1 to 12 fluorine atoms are introduced,
fluorinated oxetanes to which 1 to 6 fluorine atoms are introduced,
fluorinated 1,3-dioxolans to which 1 to 6 fluorine atoms are
introduced, and fluorinated tetrahydrofurans to which 1 to 8
fluorine atoms are introduced.
[0196] Examples of such the fluorinated ether compounds include
hexafluoro dimethyl ether, pentafluorodimethyl ether,
bis(difluoromethyl)ether, fluoromethyl trifluoromethyl ether,
trifluoromethyl methyl ether, perfluorodimethoxymethane,
1-trifluoromethoxy-1,1,2,2-tetrafluoroethane, difluoromethoxy
pentafluoroethane, 1-trifluoromethoxy-1,2,2,2-tetrafluoroethane,
1-difluoromethoxy-1,1,2,2-tetrafluoroethane,
1-difluoromethoxy-1,2,2,2-tetrafluoroethane,
1-trifluoromethoxy-2,2,2-trifluoroethane,
1-difluoromethoxy-2,2,2-trifluoroethane, perfluorooxetane,
perfluoro-1,3-dioxolan, various isomers of pentafluorooxetane, and
various isomers of tetrafluorooxetane.
[0197] In the invention, the fluorinated ether compounds maybe used
singularly or in a combination of two or more kinds thereof.
Fluorinated Alcohol Compound
[0198] According to the invention, as an example of a fluorinated
alcohol compound that can be used as a freezer refrigerant, a
fluorinated ether compound represented by, for example, the
molecular formula (A) in which R is H, p is an integer of 1 to 6, q
is an integer of 1 or 2, r is an integer of 1 to 13, and s is an
integer of 1 to 13 can be cited.
[0199] Preferable examples of such fluorinated alcohol compounds
are fluorinated compounds of linear-chain or branched aliphatic
alcohols having 1 to 6 carbon atoms and 1 or 2 hydroxyl groups.
[0200] The specific examples thereof include fluorinated methyl
alcohols to which 1 to 3 fluorine atoms are introduced, fluorinated
ethyl alcohols to which 1 to 5 fluorine atoms are introduced,
fluorinated propyl alcohols to which 1 to 7 fluorine atoms are
introduced, fluorinated butyl alcohols to which 1 to 9 fluorine
atoms are introduced, fluorinated pentyl alcohols to which 1 to 11
fluorine atoms are introduced, fluorinated ethylene glycols to
which 1 to 4 fluorine atoms are introduced, and fluorinated
propylene glycols to which 1 to 6 fluorine atoms are
introduced.
[0201] The specific examples of such fluorinated alcohol compounds
include fluorinated alcohols: such as monofluoromethyl alcohol,
difluoromethyl alcohol, trifluoromethyl alcohol, various isomers of
difluoroethyl alcohol, various isomers of trifluoroethyl alcohol,
various isomers of tetrafluoroethyl alcohol, pentafluoroethyl
alcohol, various isomers of difluoropropyl alcohol, various isomers
of trifluoropropyl alcohol, various isomers of tetrafluoropropyl
alcohol, various isomers of pentafluoropropyl alcohol, various
isomers of hexafluoropropyl alcohol, heptafluoropropyl alcohol,
various isomers of difluorobutyl alcohol, various isomers of
trifluorobutyl alcohol, various isomers of tetrafluorobutyl
alcohol, various isomers of pentafluorobutyl alcohol, various
isomers of hexafluorobutyl alcohol, various isomers of
heptafluorobutyl alcohol, and various isomers of octafluorobutyl
alcohol; fluorinated propylene glycols such as nonafluorobutyl
alcohol, various isomers of difluoroethylene glycol,
trifluoroethylene glycol, tetrafluoroethylene glycol, further
various isomers of difluoropropylene glycol, various isomers of
trifluoropropylene glycol, various isomers of tetrafluoropropylene
glycol, various isomers of pentafluoropropylene glycol, and
hexafluoropropylene glycol; and fluorinated trimethylene glycols
corresponding to the fluorinated propylene glycols.
[0202] In the invention, the fluorinated alcohol compounds may be
used singularly or in a combination of two or more kinds
thereof.
Fluorinated Ketone Compound
[0203] An example of a fluorinated ketone compound that can be used
as a freezer refrigerant according to the invention includes a
fluorinated ketone compound represented by, for example, the
molecular formula (A) in which R is H, p is an integer of 2 to 6, q
is an integer of 1 or 2, r is an integer of 1 to 12, and s is an
integer of 0 to 11.
[0204] Preferable examples of such fluorinated ketone compounds are
fluorinated compounds of aliphatic ketones having 3 to 6 carbon
atoms in which the alkyl group is linear-chained or branched.
[0205] The specific examples thereof include fluorinated acetones
to which 1 to 6 fluorine atoms are introduced, fluorinated methyl
ethyl ketones to which 1 to 8 fluorine atoms are introduced,
fluorinated diethyl ketones to which 1 to 10 fluorine atoms are
introduced, and fluorinated methyl propyl ketones to which 1 to 10
fluorine atoms are introduced.
[0206] Examples of the fluorinated ketone compounds include:
hexafluorodimethyl ketone, pentafluorodimethyl ketone, bis
(difluoromethyl) ketone, fluoromethyl trifluoromethyl ketone,
trifluoromethyl methyl ketone, perfluoromethyl ethyl ketone,
trifluoromethyl-1,1,2,2-tetrafluoroethyl ketone, difluoromethyl
pentafluoroethyl ketone, trifluoromethyl-1,1,2,2-tetrafluoroethyl
ketone, difluoromethyl-1,1,2,2-tetrafluoroethyl ketone,
difluoromethyl-1,2,2,2-tetrafluoroethyl ketone,
trifluoromethyl-2,2,2-trifluoroethyl ketone, and
difluoromethyl-2,2,2-trifluoroethyl ketone.
[0207] In the invention, the fluorinated ketone compounds may be
used singularly or in a combination of two or more thereof.
Other Additives
[0208] The refrigerator oil composition of the invention may be
added with at least one additive selected from an extreme pressure
agent, an oiliness agent, an antioxidant, an acid scavenger, a
metal deactivator and an antifoaming agent.
Extreme Pressure Agent
[0209] Examples of the extreme pressure agents include
phosphorus-base extreme pressure agents such as phosphate ester,
acid phosphate ester, phosphite ester, acid phosphite ester and
amine salts thereof.
[0210] Among the above phosphorus-base extreme pressure agents,
particularly preferable examples thereof include tricresyl
phosphate, trithiophenyl phosphate, tri(nonylphenyl)phosphite,
dioleyl hydrogen phosphite, and 2-ethylhexyl diphenyl phosphite in
terms of extreme pressure properties and friction
characteristics.
[0211] Another example of the extreme pressure agent is a metal
salt of carboxylic acid. The metal salt of carboxylic acid is
preferably a metal salt of C.sub.3 to C.sub.60 carboxylic acid,
more preferably a metal salt of C.sub.3 to C.sub.30 aliphatic acid,
particularly preferably a metal salt of C.sub.12 to C.sub.30
aliphatic acid. Further, a metal salt of dimer acid or trimer acid
of the aliphatic acid, and a metal salt of C.sub.3 to C.sub.30
dicarboxylic acid can be cited. Among these, a metal salt of
C.sub.12 to C.sub.30 aliphatic acid and a metal salt of C.sub.3 to
C.sub.30 dicarboxylic acid are particularly preferable.
[0212] On the other hand, a metal of the metal salt is preferably
an alkali metal or an alkali earth metal. Particularly, an alkali
metal is suitable.
[0213] Further, examples of the extreme pressure agents and extreme
pressure agents other than those mentioned above include sulfur
type extreme pressure agents such as sulfurized fat, sulfurized
aliphatic acid, sulfurized ester, sulfurized olefin, dihydrocarvyl
polysulphide, thiocarbamates, thioterpenes, and dialkyl
thiodipropionates.
[0214] The compounding amount of the above extreme pressure agent
is in the range of preferably 0.001 to 5% by mass, or particularly
preferably 0.005 to 3% by mass with reference to the total amount
of the composition in terms of lubricity and stability. Further,
the extreme pressure agent may be used singularly or in a
combination of two or more thereof.
Oiliness Agent
[0215] Examples of the oiliness agents include, aliphatic saturated
and unsaturated monocarboxylic acids such as stearic acid and oleic
acid; polymerized aliphatic acids such as dimer acids and
hydrogenated dimer acids; hydroxy aliphatic acids such as
ricinoleic acid and 12-hydroxystearic acid; aliphatic saturated and
unsaturated monohydric alcohols such as lauryl alcohol and oleyl
alcohol; aliphatic saturated and unsaturated monoamines such as
stearyl amine and oleylamine; aliphatic saturated and unsaturated
monocarboxylic acid amides such as lauric acid amide and oleamide;
and partial esters of a polyhydric alcohol such as glycerin and
sorbitol, and an aliphatic saturated or unsaturated monocarboxylic
acid.
[0216] In addition, these oiliness agents may be used singularly or
in a combination of two or more kinds thereof. The compounding
amount thereof is selected preferably from the range of 0.01 to 10%
by mass, more preferably from the range of 0.1 to 5% by mass with
respect to a total amount of the composition.
Antioxidant
[0217] It is preferable to mix, as an antioxidant, a phenol base
antioxidant such as 2,6-di-tert-butyl-4-methylphenol,
2,6-di-tert-butyl-4-ethylphenol or 2,2'-methylenebis
(4-methyl-6-tert-butylphenol) or an amine-base antioxidant such as
phenyl-.alpha.-naphthylamine or N,N'-diphenyl-p-phenylenediamine.
In view of effects and economic efficiency, the antioxidant is
preferably contained in the composition at a content of 0.01 to 5%
by mass, more preferably at a content of 0.05 to 3% by mass.
Acid Scavenger
[0218] Examples of the acid scavengers include epoxy compounds such
as phenyl glycidyl ethers, alkyl glycidyl ethers, alkylene glycol
glycidyl ethers, cyclohexene oxide, .alpha.-olefin oxide and
epoxidized soybean oil. As the acid scavenger, at least one kind
selected from glycidyl esters, glycidyl ethers, and .alpha.-olefin
oxide is preferable.
[0219] As the glycidyl ester, glycidyl esters of usually C.sub.3 to
C.sub.30, preferably C.sub.4 to C.sub.24, more preferably C.sub.6
to C.sub.16 straight chained, branched or cyclic saturated or
unsaturated aliphatic carboxylic acids or aromatic carboxylic acids
can be cited. The aliphatic carboxylic acid or aromatic carboxylic
acid may be a monocarboxylic acid or a polycarboxylic acid. In the
case of the polycarboxylic acid, from the viewpoint of suppressing
the acid value from rising to secure the stability of the
lubricating oil composition, an entirety of carboxyl groups is
preferably glycidyl esterized.
[0220] Among these, glycidyl esters of C.sub.6 to C.sub.16 straight
chained, branched, or cyclic saturated aliphatic monocarboxylic
acids are particularly preferred. Examples of such the glycidyl
esters include 2-ethylhexanoic acid glycidyl ester,
3,5,5-trimethylhexanoic acid glycidyl ester, caproic acid glycidyl
ester, lauric acid glycidyl ester, versatic acid glycidyl ester,
and myristic acid glycidyl ester.
[0221] As the glycidyl ether, glycidyl ethers derived from usually
C.sub.3 to C.sub.30, preferably C.sub.4 to C.sub.24, more
preferably C.sub.6 to C.sub.16 straight chained, branched or cyclic
saturated or unsaturated aliphatic monohydric or polyhydric
alcohols or aromatic compounds having one or more hydroxyl groups
can be cited. In the case of the aliphatic polyhydric alcohols or
the aromatic compounds having two or more hydroxyl groups, from the
viewpoint of suppressing the hydroxyl group value from rising to
secure the stability of the lubricating oil composition, an entire
hydroxyl groups is preferably glycidyl etherized.
[0222] Among these, glycidyl ethers derived particularly from
C.sub.6 to C.sub.16 straight chained, branched, or cyclic saturated
aliphatic monohydric alcohols are preferred. Examples of such
glycidyl ethers include 2-ethyl ethyl glycidyl ether, isononyl
glycidyl ether, caprinoyl glycidyl ether, lauryl glycidyl ether,
and myristyl glycidyl ether.
[0223] On the other hand, as .alpha.-olefin oxide, usually C.sub.4
to C.sub.50, preferably C.sub.4 to C.sub.24, and more preferably
C.sub.6 to C.sub.16.alpha.-olefin oxides are used.
[0224] In the invention, the acid scavengers maybe used singularly
or in a combination of two or more kinds thereof. In addition, from
the viewpoint of effect and suppression of the sludge generation,
it is preferable that the content thereof is usually in the range
of 0.005 to 10% by mass, and preferably in the range of 0.05 to 6%
by mass with respect to an entire amount of the composition.
Metal Deactivator, Antifoaming Agent
[0225] As an example of the metal deactivator, a copper deactivator
such as N-[N',N'-dialkyl (C.sub.3 to C.sub.12 alkyl group)
aminomethyl]triazole can be cited. Examples of the antifoaming
agent include silicone oil and fluorinated silicone oil.
Method for Lubricating Refrigerator that uses Lubricating Oil
Composition for Compression Refrigerator
[0226] The lubricating oil composition for a compression
refrigerator of the invention is suitable for refrigerators that
use a refrigerant containing the C.sub.1 to C.sub.3 saturated
fluorinated hydrocarbon.
[0227] In the method of lubricating a refrigerator that uses the
lubricating oil composition for a refrigerator according to the
invention, used amounts of the refrigerants listed above and the
lubricating oil composition for a refrigerator are preferably in a
mass ratio of the refrigerant/lubricating oil composition for a
refrigerator of 99/1 to 10/90, more preferably in a mass ratio of
95/5 to 30/70. When the used amount of the refrigerant is less than
the above range, the freezing capability of the lubricating oil
composition is unfavorably deteriorated. On the other hand, when
the used amount of the refrigerant is more than the above range,
the lubricating capability of the lubricating oil composition is
unfavorably deteriorated. The lubricating oil composition for a
refrigerator of the invention can be used in various refrigerators
and particularly preferably applied to a compression type
refrigerating cycle of a compression refrigerator.
Refrigerator
[0228] A refrigerator to which the lubricating oil composition for
a refrigerator of the invention is applied includes a refrigerating
cycle that includes a compressor, a condenser, an expansion
mechanism (expansion valve and so on) and an evaporator as
essential components; or a refrigerating cycle that includes a
compressor, a condenser, an expansion mechanism, a dryer, and an
evaporator as essential components, uses the lubricating oil
composition for refrigerators of the invention described as a
refrigerator oil, and uses various refrigerants described above as
a refrigerant.
[0229] Here, in the above-mentioned dryer, a desiccant formed of
zeolite having a pore size of 0.33 nm or smaller is preferably
filled. The zeolite, which may be natural zeolite or synthetic
zeolite, preferably has a CO.sub.2 gas absorption capacity of 1.0%
or less at 25.degree. C. and CO.sub.2 gas partial pressure of 33
kPa. Examples of such synthetic zeolites include XH-9 (trade name)
and XH-600 (trade name) manufactured by Union Showa K.K.
[0230] In the invention, with use of such desiccant, while water is
efficiently removed without absorption of refrigerant in the
refrigerating cycle, the desiccant is prevented from being
powderized due to deterioration of the desiccant itself.
Accordingly, the choking of piping caused by powderization, and
abnormal wear of a sliding part of the compressor caused by
invasion of the powderized desiccant into the sliding part of the
compressor are prevented. Therefore, the refrigerator can be stably
driven for a long time.
[0231] The refrigerator to which the lubricating oil composition
for refrigerators of the invention is applied has various sliding
parts (bearings, for example) in a compressor. In the invention,
from the viewpoint particularly of sealability as the sliding part,
a sliding part made of engineering plastic, or having an organic
coating film or an inorganic coating film can be preferably
used.
[0232] As the engineering plastic, from the viewpoint of
sealability, slidability, and wear resistance, a polyamide resin, a
polyphenylene sulfide resin, a polyacetal resin can be preferably
cited.
[0233] In addition, as the organic coating film, from the viewpoint
of sealability, slidability and wear resistance, a
fluorine-containing resin coating film (polytetrafluoroethylene
coating film), a polyimide coating film, a polyamide coating film,
and, a thermo-setting resin insulating film formed with a resin
coating material containing a resin base material made of a
polyhydroxy ether resin and a polysulfonic resin and a crosslinking
agent can be cited.
[0234] On the other hand, as the inorganic coating film, from the
viewpoint of sealability, slidability, and wear resistance, a
graphite film, a diamond-like carbon film, a nickel film, a
molybdenum film, a tin film, and a chromium film can be cited. The
inorganic film may be formed according to plating or a PVD method
(physical vapor deposition method).
[0235] As the sliding part, also conventional alloy-base such as
Fe-base alloy, Al-base alloy or Cu-base alloy can be used.
System that uses Lubricating Oil Composition for Refrigerator
[0236] The lubricating oil composition for a compression
refrigerator of the invention can be used for car air conditioners,
electric car air conditioners, gas heat-pumps, air conditioners,
refrigerated chambers, automatic vending machines, show cases,
various hot-water supply systems, and freezing and heating
systems.
[0237] In the invention, the moisture content in the various
systems to which a lubricating oil composition for a refrigerator
is applied is preferably 300 ppm by mass or less, and more
preferably 200 ppm by mass or less. Further, partial pressure of
the residual air in the system is preferably 10 kPa or less and
more preferably 5 kPa or less.
[0238] The lubricating oil composition for a compression
refrigerator of the invention contains, as a base oil, a specific
oxygen-containing compound as a main component, and, because of low
viscosity, energy saving property can be improved and sealability
is excellent.
EXAMPLE
[0239] Hereinafter, the invention will be described in more detail
with reference to Examples. However, the invention is not at all
limited to these examples.
[0240] Properties of the base oil and various characteristics of
the lubricating oil composition for refrigerators were obtained
according to the procedure shown below.
Properties of Base Oil
[0241] (1) Kinematic viscosity at 100.degree. C.
[0242] The kinematic viscosity at 100.degree. C. was measured
according to JIS K 2283-1983 by using a glass capillary
viscometer.
[0243] (2) Number Average Molecular Weight
[0244] The number average molecular weight was measured by gel
permeation chromatography (GPC). The GPC was conducted using
HLC-8120GPC, SC-8020 (trade name, manufactured by TOSOH
Corporation), THF (tetrahydrofuran) as an eluting solution, and an
IR detector. From the result, based on a calibration curve due to
polystyrene reference sample, the number average molecular weight
was obtained.
[0245] (3) Flashing point
[0246] The flashing point was measured according to JIS K 2265
(C.O.C method).
[0247] (4) Viscosity Index
[0248] The viscosity index was measured according to JIS K
2283.
Thermal Stability Test of Lubricating Oil Composition for
Refrigerators
[0249] In a 200 mL autoclave, oil/refrigerant (ratio: 30 g/30 g,
moisture content in oil: 500 ppm by mass), and a metal catalyst
made of iron, copper and aluminum were charged and encapsulated,
after keeping under condition of air pressure of 18.7 kPa, and
temperature of 200.degree. C. for 240 hr, oil appearance was
visually observed, and the acid value was measured. The acid value
was measured by an indicator method according to "Petroleum
products and lubricants-Neutralization Test Method" stipulated by
JIS K 2501.
Compounding Component
[0250] Kinds of respective components used to prepare the
lubricating oil composition for a refrigerator are shown below.
[0251] (1) Base oil [0252] A1: Poly(ethyl vinyl ether) (kinematic
viscosity at 100.degree. C.: 15.97 mm.sup.2/s, flashing point:
222.degree. C., the number average molecular weight: 1250,
viscosity index: 85) [0253] A2: Polypropylene glycol dimethyl ether
(kinematic viscosity at 100.degree. C.: 9.25 mm.sup.2/s, flashing
point: 212.degree. C., the number average molecular weight: 1139,
viscosity index: 207) [0254] A3: Polypropylene glycol
(PPG)/poly(ethyl vinyl ether) (PEV) copolymer (PPG/EVE molar ratio:
7/11) (kinematic viscosity at 100.degree. C.: 9.56 mm.sup.2/s,
flashing point: 218.degree. C., the number average molecular
weight: 1200, viscosity index: 140) [0255] A4: Pentaerythritol
octanoic acid (C.sub.8 acid) nonanoic acid (C.sub.9 acid) ester
(C.sub.8 acid/C.sub.9 acid molar ratio: 1/1.1) (kinematic viscosity
at 100.degree. C.: 9.64 mm.sup.2/s, flashing point: 268.degree. C.,
the number average molecular weight: 670, viscosity index: 126)
[0256] (2) Stabilizer (organic compound having double bond in
molecule) [0257] B1: .beta.-pinene [0258] B2: 1,4-p-mentadiene
[0259] B3: 1,4-cyclohexadiene [0260] B4: 1,4-hexadiene [0261] B5:
2,5-norbornadiene [0262] B6: 1-hexadecene
[0263] (3) Additive
[0264] With the following respective components, compounding
amounts in an entire composition were set respectively to amounts
(% by mass) shown in bracket, and the extreme pressure agent and
defoaming agent (other additives) were added to be 1.10% by mass in
total. [0265] Acid scavenger: 2-ethylhexyl glycidyl ether (0.3% by
mass) [0266] Antioxidant: 2,6-di-t-butyl-4-methyl phenol (0.3% by
mass) [0267] Extreme pressure agent: tricresyl phosphate (1.0% by
mass) [0268] Antifoaming agent: silicone-based antifoaming agent
(0.1% by mass)
Examples 1 to 9 and Comparative Examples 1 to 7
[0269] Lubricating oil compositions for a refrigerator each having
a composition shown in Table 1 and Table 2 were prepared, and with
R32 (difluoromethane) or R410A [50:50 mixture by mass ratio of R32
and R125 (pentafluoroethane)] as a refrigerant, the thermal
stability of the compositions were evaluated. Results thereof are
shown in Table 1 and Table 2.
TABLE-US-00001 TABLE 1-1 Examples 1 2 3 4 5 6 7 8 9 Compounded Base
oil A1 97.3 97.3 97.3 97.3 97.3 97.3 -- -- -- composition A2 -- --
-- -- -- -- 97.3 -- -- (% by A3 -- -- -- -- -- -- -- 97.3 -- mass)
A4 -- -- -- -- -- -- -- -- 97.3 Stabilizer B1 1.0 -- -- -- -- --
1.0 1.0 1.0 B2 -- 1.0 -- -- -- -- -- -- -- B3 -- -- 1.0 -- -- -- --
-- -- B4 -- -- -- 1.0 -- -- -- -- -- B5 -- -- -- -- 1.0 -- -- -- --
B6 -- -- -- -- -- 1.0 -- -- -- Antioxidant 0.3 0.3 0.3 0.3 0.3 0.3
0.3 0.3 0.3 Acid scavenger 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3
Other additive 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Thermal
stability test Refrigerant R32 Acid value 0.71 0.81 0.82 0.86 0.79
1.02 0.78 0.75 0.82 (mgKOH/g) Oil appearance Pale Pale Pale Pale
Pale Pale Pale Pale Pale yellow yellow yellow yellow yellow yellow
yellow yellow yellow
TABLE-US-00002 TABLE 1-2 Comparative Examples 1 2 3 4 5 6 7
Compounded Base oil A1 98.3 98.3 98.1 97.6 -- -- -- composition A2
-- -- -- -- 98.3 -- -- (% by A3 -- -- -- -- -- 98.3 -- mass) A4 --
-- -- -- -- -- 98.3 Antioxidant 0.3 0.3 0.5 0.3 0.3 0.3 0.3 Acid
scavenger 0.3 0.3 0.3 1.0 0.3 0.3 0.3 Other additive 1.1 1.1 1.1
1.1 1.1 1.1 1.1 Thermal stability test Refrigerant R32 R410A R32
R32 R32 R32 R32 Acid value 1.54 1.20 1.55 1.51 1.40 1.55 1.56
(mgKOH/g) Oil appearance Orange Yellow Orange Orange Orange Orange
Orange
[0270] From Table 1 and Table 2, the followings are found.
[0271] In all of Examples 1 to 9 where a lubricating oil
composition for a compression refrigerator of the invention was
used in a system where R32 (difluoromethane) was used as a
refrigerant, in thermal and oxidation stability test, oil
appearance was excellent and also the acid value was low.
[0272] By contrast, in Comparative Examples 1 to 7 where an organic
compound (stabilizer) having a double bond in the molecule
according to the invention was not used, not only the acid value
was high, but also the oil appearance turned to yellow or
orange.
[0273] Further, Comparative Example 1 where the same lubricating
oil composition for a compression refrigerator in the invention, in
which the stabilizer was not used was used, and R32
(difluoromethane 100%) was used as the refrigerant compared poorly
with Comparative example 2 where R410A (a refrigerant obtained by
mixing R32 and R125 at a mass ratio of 50:50) was used as a
refrigerant in that the acid value was high and oil appearance was
orange or yellow.
Industrial Applicability
[0274] The lubricating oil composition for a compression
refrigerator of the invention exhibits excellent thermal and
oxidation stability when used in a compression refrigerator that
uses a refrigerant that uses C.sub.1 to C.sub.3 saturated
fluorinated hydrocarbon that is a refrigerant that is low in the
global warming potent and can be used in particular in an air
conditioner and a car air conditioner.
* * * * *