DESCRlPTION
' Title of Invention: REFRIGERATOR OIL AND REFRIGERATOR
WOFKNG FLUID COMPOSITION
Technical Field
5 [0001] The present invention relates lo a refrigerating machine oil and a
working fluid composition for a refrigerating machine.
Background Art
[0002] Against the background of the recent problem of ozone layer
depletion, CFC (chlorofluorocarbon) and HCFC (hydrochloro-
10 fluorocarbon) conventionally used as refrigerants for refrigerating
machines are subject to regulation and, instead of them, HFC
(hydrofluorocarbon) is becoming widely used as a refrigerant.
However, one of the HFC refkigerants, HFC-134a, which is commonly
used as a refrigerant for car air conditioners, is subject to regulation in
15 Europe due to its high global warming potential (GWP) although its
ozone-depleting potential (ODP) is zero.
[0003] Under such circumstances, there have been an urgent need to
develop a rekigerant that has a small influence on the ozone layer and
has a low GW. For example, Patent Literature 1 discloses a
20 tiifluoroethylene (HFO-1123) rekigerant as a refrigerant that has a
small influence on the ozone layer and has a low GWP.
[0004] In the conventional case where CFC or IEFC is used as a
rekigerant, a rekigerating machine oil containing a mineral oil or a
hydrocarbon oil such as alkylbenzene has been suitably used.
25 Depending on the type of the coexisting refrigerant, a refrigerating
inachii oil may show unexpected behaviors in terms of its
compatibility with the refrigerant, its luibricating properties, the
viscosity of its solution in the refrigerant, or its thermal and chemical
stability, which is why different refiigerating machine oils need to be
developed for different refrigerants.
5 Citation List
Patent Literature
[0005] Patent Literature 1: lnteinational Publication No. WO
2012/157764
Summary of Inventiot~
10 Technical Problem
[OOOG] The object of the present invention is to provide a refiigerating
machine oil superior in confomnlity with trifluoroethylene @FO-1123)
refrigerants and a working fluid coinposition for a refrigerating machine
comprising the refrigerating machine oil.
15 Solution to Problem
[0007] The present invention provides a refrigerating machine oil
comprising at least one oxygen-containing oil having a carbonloxygen
molar ratio of 2.5 or more and 5.8 or less as a base oil, the refrigerating
machine oil being used with a trifluoroethylene refrigerant.
20 [0008] The present invention also provides a working fluid composition
for a refrigerating machine comprising: a refrigerating machine oil
cornprising at least one oxygen-containing oil having a carbonloxygen
molar ratio of 2.5 or more and 5.8 or less as a base oil; and a
trifluoroethylene refrigerant.
25 [0009] It is preferable for the above refrigerating machine oil to
comprise an ester of a fatty acid and a polyhydric alcohol as the
oxygen-containiug oil, the fatty acid comprising a branched fatty acid
having 4 to 9 carbon atoms in a proportion of 20 to 100 mol%.
Advantageous Effects of Invention
[0010] The present invention can provide a refiigerating machine oil
5 superior in conformity with trifluoroethylene -0-1123) refrigerants
and a working fluid composition for a refrigerating machine comprising
the refrigerating machine oil.
Description of Embodiments
[0011] Hereinafter, preferred embodiments of the present invention will
10 be described in detail.
[0012] A refrigerating machine oil according to the present embodiment
cotnprises at least one oxygen-containing oil having a carbon/oxygen
molar ratio of 2.5 or more and 5.8 or less as a base oil and is used with a
trifluoroethylene refrigerant.
15 [0013] A working fluid composition for a refrigerating machine
according to the present embodiment comprises: a refigerating machine
oil comprising at least one oxygen-containing oil having a
carbonloxygen molar ratio of 2.5 or more and 5.8 or less as a base oil;
and a trifluoroethylene refrigerant. The working fluid co~npositionf or
20 a refrigerating machine according to the present embodiment
encompasses embodiments in which the conlposition comprises the
refrigerating machine oil according to the present embodiment and a
trifluoroethylene refrigerant.
[0014] The base oil is at least one oxygen-containing oil having a
25 carbonloxygen molar ratio of 2.5 or more and 5.8 or less. The
carbonfoxygen molar ratio of such an oxygen-containing oil is
preferably 3.2 or more, more preferably 4.0 or more and is preferably
5.0 or less, in terms of the compatibility with refrigerants and of the
stability. The carbonloxygen molar ratio can be quantitatively
analyzed by a common elemental analysis method. One example of
5 the method for analyziug carbon is a method in which the analysis is
conducted by a thermal conductivity technique or gas chromatography
after conversion to carbon dioxidc by burning. Carbon reduction
process, in which quantitative analysis is conducted after oxygen is
converted to carbon monoxide using carbon, is typical as the method for
10 analyzing oxygen, aud Shutze-Unterzaucher method has been widely
used in practice.
[0015] Examples of the oxygen-containing oil include esters, polyvinyl
ethers, polyalkylene glycol carbonates, ketones, polyphenyl ethers,
silicones, polysiloxaues, and perfluoroethers, among which an ester, a
15 polyvinyl ether, or a polyalkylene glycol is preferred and an ester is
more preferred.
[0016] Examples of the ester include an aromatic ester, a dibasic acid
ester, a polyol ester, a complex ester, a carbonic acid ester, and mixtures
thereof, and a polyol ester is preferred.
20 [0017] As the aromatic ester there is used, for example, an ester of an
aromatic carboxylic acid having 1 to 6, preferably 1 to 4, more
preferably 1 to 3 carboxyl groups and an aliphatic alcohol having 1 to
18, preferably 1 to 12 carbon atoms. Specific examples of the
aromatic carboxylic acid having 1 to 6 carboxylic groups include
25 benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic
acid, pyromellitic acid, and mixtures thereof. Specific examples of the
FP14-0664-00 !
i
i
aliphatic alcoliol having 1 to 18 carbon atoms include methanol,
i
I I
i
ethanol, propanol, buianol, pentanol, hexanol, heptanol, octanol, i
nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol,
pentadecanol, hexadecanol, heptadecanol, octadecanol, and mixtuses
5 thereof. These aliphatic alcohols having 1 to 18 carbon atoms may be
linear or branched. An aromatic carboxylic acid having two or more
carboxyl groups may be a simple ester formed of an alcohol consisting
of one aliphatic alcohol or may be a complex ester formed of an alcohol
consisting of two or more aliphatic alcohols.
10 [0018] As the dibasic acid ester there are preferably used: estexs of
dibasic acids having 5 to 10 carbon atoms, such as glutaric acid, adipic
acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, and I
monohydric alcohols having 1 to 15 carbon atoms and having a hear or I
branched alkyl goup, such as methanol, ethanol, propanol, butanol, I
!
i
15 pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol,
dodecanol, tridecanol, tetradecanol, and pentadecanol; and mixtures of
thcse esters.
[0019] The polyol ester is an ester synthesized fiom a polyhydric
alcohol and a fatty acid. As the fatty acid there is preferably used a
20 saturated fatty acid. It is preferable that the number of carbon atoms in
the fatty acid be 4 to 9, more preferably 5 to 9. The polyol ester may
.be a paifial ester in which some of the hydsoxyl groups of the
polyhydric alcohol remain as hydroxyl groups withotit being esterified,
may be a complete ester in which all of the hydroxyl goups have been
25 esterified, or may be a mixture of the partial ester and the complete
ester. The hydroxyl value of the polyol ester is preferably 10
mgKOWg or less, more preferably 5 111g1<0FT/g or less, and even more
preferably 3 mgKOWg or less.
[00201 It is preferable that the propoltion of a branched fatty acid in the
fatty acid for forming the polyol ester be 20 to 100 mol%, more
5 preferably 50 to 100 mol%, e\!en more preferably 70 to 100 mol%,
particularly preferably 90 to 100 mol%. 'In particular, it is preferable
that the propoltion of a branched fatty acid having 4 to 9 carbon atoms
be within the above range.
[0021] Specific examples of the branched fatty acid having 4 to 9
10 carbon atoms include branched butanoic acid, branched pentanoic acid,
branched hexanoic acid, blanched heptanoic acid, branched octanoic
acid, and branched nonanoic acid. More specifically, preferred are
fatty acids branched at the a position and/or the f3 position, preferred
examples of which include isobutanoic acid, 2-methylbutanoic acid,
15 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid,
2-methylheptanoic acid, Zethylhexanoic acid, and 3,5,5-
trimethylhexanoic acid, among which 2-ethylhexanoic acid and/or
3,5,5-trimethylhexanoic acid is more preferred.
[0022] The fatty acid may comprise a fatty acid other than the branched
20 fatty acid having 4 to 9 carbon atoms. As the fatty acid other than the
branched fatty acid having 4 to 9 carbon atoms there is preferably used,
for example, a linear fatty acid having 4 to 9 carbon atoms (that is,
n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid,
n-octanoic acid, or n-nonanoic acid). Among these, pentanoic acid
25 andlor heptanoic acid is more preferred.
[0023] The fatty acid may comprise, for example, a fatty acid having 10
to 24 carbon atoms as the fatty acid other than the fatty acid having 4 to
9 carbon atoms. Specific examples of the fatty acid having 10 to 24
carbon atoins include decanoic acid, undecanoic acid, dodecanoic acid,
tridecanoic acid, tetradccanoic acid, pentadccanoic acid, hexadccanoic
5 acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid,
icosanoic acid, heneicosanoic acid, docosanoic acid, tricosanoic acid,
and tetracosanoic acid. These fatty acids having 10 to 24 carbon atoms
may be linear or branched.
[0024] As the polyhydric alcohol for forming the polyol ester there is
10 preferably used a polyhydric alcohol having 2 to 6 hydroxyl groups.
The number of carbon atoms in the polyhydric alcohol is prefer-ably 4 or
more and more preferably 5 or more and is preferably 12 or less and
more preferably 10 or less. Specifically, hindered alcohols such as
neopentyl glycol, trimethylolethane, trimethylolpropane,
15 trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane),
pentaerythritol, and dipentaelythritol are preferred. Pentaerythritol or
a mixed ester of pentaerythritol and dipentaerythritol is more preferred
in that compatibility with refkigerants and hydrolysis stability arc
pa~ticularlys uperior.
20 [0025] The complex ester is an ester of a fatty acid and a dibasic acid
with a monohydric alcohol and a polyol. As the fatty acid, the dibasic
acid, the monohydric alcohol, and the polyol there can be used the same
as those which are mentioned as examples in the descriptions of the
dibasic acid ester and the polyol ester.
25 [0026] The carbonic acid ester is a compound having a carbonic acid
ester structure represented by the following formula (A) in the
molecule. The carbonic acid ester may have one carbonic acid ester
structure or two or more such structures per molecule.
[0027] [Chemical Formula 11
-C-0-C-0-C- I I (A)
0
[0028] As the alcohol for forming the carbonic acid ester there can be
used, for example, the aliphatic alcohols and polyols as mentioned
above and, alternatively, polyglycol or an adduct of a polyol with
polyglycol can be used. The carbonic acid ester may include a
carbonic acid and a fatty acid and/or a dibasic acid.
[0029] Among carbonic acid esters, a carbonic acid ester having a
structure represented by the following formula (A-1) is preferred.
[0030] [Chemical Foimula 21
[In the above fo~mula(A -1), x1r epresents a hydrogen atom, an
alkyl group, a cycloalkyl group, or a group represented by the following
formula (A-2):
Y~-(oA~), (A-2)
(in the above formula (A-2), Y' represents a hydrogen atom, an
alkyl group, or a cycloallcyl group, pol represents an alkylene group
having 2 to 4 carbon atoms, and e represents an integer of 1 to 50), A'
and A' may be the same or different and each represent an alkylene
group having 2 to 4 carbon atoms, Y' represents a hydrogen atom, an
alkyl group, or a cycloalkyl group, B represents a residue of a
compound having 3 to 20 hydroxyl groups, a represents an integer of 1
to 20, b represents an integer of 0 to 19, a + b is 3 to 20, c represents an
integer of 0 to 50, and d represents an integer of 1 to SO.]
[0031] In the above formula (A-I), X' represents a hydrogen atom, an
allcyl group, a cycloalkyl group, or a group represented by the above
5 foimula (A-2). The number of carbon atoms in the alkyl group is not
particularly limited, but is typically 1 to 24, preferably 1 to 18, and more
preferably 1 to 12. The alkyl group may be lhes or brancl~ed.
[0032] Specific examples of the alkyl group having 1 to 24 carbon
atoms include: a methyl group, an ethyl group, an n-propyl group, an
10 isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group,
a tert-butyl group, a linear or branched pentyl group, a linear or
branched hexyl group, a linear or branched heptyl group, a linear or
branched octyl group, a linear or branched nonyl group, a hear or
branched decyl group, a linear or branched undecyl group, a linear or
15 branched dodecyl group, a linear or branched tridecyl group, a linear or
branched tetradecyl group, a linear or branched pentadecyl group, a
linear or branched hexadecyl group, a linear or branched heptadecyl
group, a linear or branched octadecyl group, a linear or branched
nonadecyl group, a linear or branched eicosyl group, a linear or
20 branched heneicosyl group, a linear or branched docosyl group, a linear
or branched tricosyl group, and a linear or branched tetracosyl group.
[0033] Specific examples of the cycloallcyl group include a cyclopentyl
group, a cyclohex-yl group, and a cycloheptyl group.
[0034] Examples of the alblene group having 2 to 4 carboil atoms
25 .which is represented by in the above formula (A-2) include an
ethylene group, a propylene group, a triniethylene group, a butylene
group, a tetrainethylene group, a 1-methyltrimetl~ylene group, a
2-methylttimethylene group, a 1,l-dimetlylcthylene group, and a
1,2-dimethylethylene group.
[0035] Y' in the above fomula (A-2) is a hydrogen atom, an alkyl
5 group, or a cycloalkyl group. The number of carbon atoms in the alkyl
group is not particularly limited, but is typically 1 to 24, prefcrably 1 to
18, and more preferably 1 to 12. The alkyl group may be linear or
branched. Specific examples of the akyl group having I to 24 carbon
atoms include the groups listed in the description of x'.
10 LO0361 Specific cxamples of the cycloalkyl group include a cyclopentyl
group, a cyclohexyl gsoup, and a cycloheptyl group.
[0037] It is preferable for Y' to be a hydrogen atom or an alkyl group
having 1 to 12 carbon atoms among these examples, and it is more
preferable for y2 to be a hydrogen atom, a methyl group, an ethyl group,
15 an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl
group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an
iso-pentyl gsoup, n neo-pentyl group, an n-hexyl group, an iso-hexyl
group, an n-heptyl group, an iso-heptyl group, an n-octyl group, an
iso-octyl group, an n-nonyl group, an iso-nonyl group, ann-decyl group,
20 an iso-decyl group, an n-undecyl group, an iso-undecyl group, an
11-dodecyl group, or an iso-dodecyl group.
[0038] It is preferable for X' to be a hydrogen atom, an alkyl group
having 1 to 12 carbon atoms, or a group represented by the formula
(A-2), and it is more preferable for X' to be a hydrogen atoll,, a methyl
25 group, an ethyl group, an n-propyl group, an iso-propyl group, an
n-butyl group, an iso-butyl group, a sec-butyl gsoup, a test-butyl group,
an n-pentyl group, an iso-pentyl group, a neo-pentyl group, an n-hexyl
group, an iso-hexyl group, an n-heptyl group, an iso-heptyl group, an
n-octyl group, an iso-octyl group, an n-nonyl group, an iso-nonyl group,
an n-decyl group, an iso-decyl group, an n-undecyl group, an
5 iso-undecyl group, an n-dodecyl group, an iso-dodecyl group, or a
goup represented by the formula (A-2).
[0039] Specific examples of the compound that has 3 to 20 hydroxyl
groups and whose residue is B include the polyols mentioned above.
[0040] A' and A' may be the same or different and each represent an
10 alkylene group having 2 to 4 carbon atoms. Specific examples include
an ethylene group, a propylene group, a trimethylene group, a butylene
group, a tetramethylene group, a 1-methyltrimethylene group, a
2-methyltrimethylene group, a l,l-dimethylethylene group, and a
1,2-dimethylethylene group.
15 [0041] Y' is a hydrogen atom, an alkyl group, or a cycloalkyl group.
The number of carbon atoms in the alkyl group is not particularly
limited, but is typically 1 to 24, preferably 1 to 18, and more preferably
1 to 12. The alkyl group may be linear or branched. Specific
examples of the alkyl group having 1 to 24 carbon atoms include the
20 groups listed in the description of x'.
[0042] Specific examples of the cycloalkyl group include a cyclopentyl
group, a cyclohexyl group, and a cyclol~eptygl roup.
[0043] It is preferable for Y' to be a hydrogen atom or an alkyl group
having I to 12 carbon atoms among these examples, and it is more
25 preferable for Y' to be a hydrogen atom, a methyl group, an ethyl group,
an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl
group, a secbutyl group, a tert-butyl group, an n-pentyl group, an
iso-pentyl group, a neo-pentyl group, an 11-hexyl group, an iso-hexyl
group, an n-heptyl goup, an iso-heptyl group, an n-octyl group, an
iso-octyl group, an n-nonyl group, an iso-nonyl group, an n-decyl group,
5 an iso-decyl group, an n-undecyl group, an iso-undecyl group, an
n-dodecyl group, or an iso-dodecyl group.
[0044] In the above formulae (A-1) and (A-2), c, d, and e each
represent a degee of poly~nerization of a polyoxyalkylene moiety.
These polyoxyalkylene moieties may have one type of oxyalkylene
10 group or two or more types of oxyalkylene groups. When the
polyoxyalkylene moieties have two or more types of polyoxyalkylene
groups, the polymerization form of each oxyalkylene group is not
particularly limited, and may be random copolymerization or block
copolymerization.
15 [0045] The polyvinyl ether has a structural unit represented by the
following formula (1).
[0046] [Chemical Formula 31
[In the fo~mula,R ', R ~a,n d R~ may be the same or different
20 from each other, and each represent a hydrogen atom or a hydrocarbon
group, R4 represents a divalent hydrocarbon group or a divalent,
ether-linked oxygen-containing hydrocarbon group, R5 represents a
hydrocarbon group, and m represents an integer of 0 or more. When nl
is 2 or more, two or more R4 may be the same or digerent from each
other.
[0047] The number of carbon atoms in the hydrocarbon groups
representcd by R', R2, and R3 in the formula (I) is preferably 1 or more,
5 more preferably 2 or more, and even more preferably 3 or more, and is
preferably 8 or less, more preferably 7 or lcss, and even more preferably
6 or less. It is preferable that at least one of R1, R2, and R3 in the
formula (I) be a hydrogen atom, and it is more preferable that all of R',
R2, and R' be a hydrogen atom.
10 [0048] The number of carbon atoms in the divalent hydrocarbon group
or ether-linked oxygen-containing hydrocarbon group represented by R4
in the formula (1) is preferably 1 or more, Inore preferably 2 or more,
and even more preferably 3 or more, and is preferably 10 or less, more
preferably 8 or less, and even more prefembly 6 or less. The divalent,
15 ether-linked oxygen-containing hydrocarbon group represented by R~ in
the foimula (1) may be, for example, a hydrocarbon group having an
oxygen atom forming an ether bond in a side chain.
[0049] It is preferable for R5 in the formula (I) to be a hydrocarbon
group having 1 to 20 carbon atoms. Examples of this hydrocarbon
20 group include an allcyl group, a cycloalkyl group, a phenyl group, an
aryl group, and an asylalkyl group. Among these, an alkyl group is
preferred, and an alkyl group having 1 to 5 carbon atoms is more
prefessed.
[0050] m in the formula (1) is preferably 0 or more, more preferably 1
25 or more, and even more preferably 2 or more, and is preferably 20 or
less, more preferably 18 or less, and even more preferably 16 or less.
It is preferable that the average of m in all the structuual units
constituting the polyvinyl ether be 0 to 10.
[0051] The polyvinyl ether may be a homopolytner constituted by one
type of structural unit selected fiotn those represeizted by the forinula
5 (I), may be a copolymer constituted by two or more types of structural
units selected from those represented by the formula (I), or may be a
copolymer constituted by a structural unit represented by the forinula
(1) and another sttuctural unit. With the polyvinyl ether being a
copolymer, the requirement for the compatibility of the refrigerating
10 machine oil with refrigerants can be met and, at the same time, the
lubricating properties, electrical insulating properties, and hygroscopic
properties or the like can be further improved. In this case, the above
various properties of the refrigerating machine oil can be made desirable
by appropriately selecting, for example, the type of the monomer as a
15 raw material, the type of an initiator, and the ratio between the structural
units in the copolymer. It is therefore possible to freely obtain a
refrigerating machine oil meeting the requirements, for example, for
lubricating properties and compatibility which vary depending on, for
example, the type of a compressor in a refrigerating system or an
20 air-conditioning system, the material of the part to be lubricated, the
refrigerating capacity, and the type of the refiigerant. The copolymer
may be either a block copolymer or a random copolymer.
[0052] When the polyvinyl ether is a copolymer, it is preferable for the
copolymer to have: a structural unit (1-1) represented by the above
25 formula (1) where R~ is an allcyl group having 1 to 3 carbon atoms; and
a structural unit (1-2) represented by the above formula (I) where R~ is
an alkyl group having 3 to 20, preferably 3 to 10,. more preferably 3 to 8
carbon atoms. An ethyl group is particularly preferred as RS in the
str~rcturaul nit (I-I), and an isobutyl group is particularly preferred as R~
in the stluctural unit (1-2). When the poljvinyl ether is a copolymer
5 having the above structural units (1-1) and (1-2), it is preferable that the
nlolar ratio between the structural unit (1-1) and tlie structural unit (1-2)
be 5 : 95 to 95 : 5, more preferably 20 : 80 to 90 : 10, even more
preferably 70 : 30 to 90 : 10. When the molar ratio is within the above
range, it is likely that the compatibility with refrigerants can Mher be
10 improved and the moisture uptake can be reduced.
[0053] Although the polyvinyl ether may consist only of the structural
units represented by the above fo~mula( 1) or ]nay alternatively be a
copolymer further having a structural unit represented by the following
formula (2). Tn this case, the copolymer may be either a block
15 copolymer or a random copolymer.
[0054] [Chemical Formula 41
Fn the formula, R6 to R' may be the same or different ffom each
other and each represent a hydrogen atom or a l~ydrocarbon group
20 having 1 to 20 carbon atoms.]
[0055] The polyviiiyl ether can be produced by polymerization of a
viuyl ether monomer corresponding to the folmula (1) or
copolymerization of a vinyl ether monomer corresponding to the
formula (1) and an olefinic double bond-containing hydrocarbon
monomer corresponding to the formula (2). A monomer represented
by the following formula (3) is suitable as the vinyl ether monomer
corresponding to the structural unit represented by the fo~luula(1 ).
[0056] [Chemical Folmula 51
R' R~
[In the formula, R', RZ, R3, R4, R5, and m respectively represent
the same as defined for R', R2,R 3,R ~R,5 ,a nd m in the formula (I).]
[0057] It is preferable for the polyvinyl ether to have the following
te~minasl tructure (A) or @).
[0058] (A) A structure having one terminal represented by the formula
(4) or (5) and the other terminal represented by the formula (6) or (7).
[0059] [Chemical Formula 61
the formula, R", R2', and R3' may be the same or different
from each other and each represent a hydrogen atom or a hydrocarbon
group having 1 to 8 carbon atoms, R4' represents a divalent hydrocarbon
group or divalent ether-linked oxygen-containing hydrocarbon group
having 1 to 10 carbon atoms, R5' represents a hydrocarbon group having
1 to 20 carbon atoms, and m represents the same as defined for m in the
formula (1). When m is 2 or more, two or more R~~m ay be the same
or different £son1 each other.]
[0060] [Chemical Formula 71
[In the foonnula, R~', R7', R", and R~' may be the same or
different &om each other and each represent a hydrogen atom or a
5 hydrocarbon group having 1 to 20 carbon atoms.]
[0061] [Chemical Formula 81
~ 1 2~ 2 2
I 1
-C-CH (6)
I I
RS2 O(R~~O),,,R~~
the folmula, R'~,R ~an~d R, ~ ~m ay be the same or diierent
from each other and each represent a hydrogen atom or a hydrocarbon
10 group having 1 to 8 carbon atoms, R~~re presents a divalent hydrocarbon
group or divalent ether-linked oxygen-containing hydrocarbon group
having 1 to 10 carbon atoms, RS2 represents a hydrocarbon group having
1 to 20 carbon atoms, and m represents the same as defined for in in the
formula (1). When In is 2 or more, two or more R~~ may be the same
15 or different.]
(00621 [Chemical Fonnula 91
~ 6 2~ 7 2
- I I
C-CH (7)
I I ~ 8 2~ 9 2
[In the fortnula, R6', R ~R~~',, a nd Rq2 may be the same or
diierent ikom each other and each represent a hydrogen atom or a
20 hydrocarbon group having 1 to 20 carbon aloms.]
LO0631 @) A structure laving one terminal represented by the above
fo~inula( 4) or (5) and the other terminal represented by the following
formula (8).
[0064] [Chemical Folmula 101
[In the formula, RI3, R ~an~d R,' ~m ay be the same or different
fi.om each other and each represent a hydrogen atom or a hydrocarbon
group having 1 to 8 carbon ato~ns.]
[0065] Among such polyvinyl ethers, polyvinyl ethers corresponding to
10 (a), (b), (c), (d), and (e) listed below are particularly suitable as a main
component (base oil) of the reiiigerating machine oil.
(a) A polyvinyl ether that has a structure having one te~minal
represented by the formula (4) or (5) and the other terminal represented
by the formula (6) or (7) and for which, in the fo~mula(I ), R', R', and
15 R3 are each a hydrogen atom, m is an integer of 0 to 4, IX4 is a divalent
hydrocarbon group having 2 to 4 carbon atoms, and R5 is a hydrocarbon
group having 1 to 20 carbon atoms.
(b) A polyvinyl ether that has only the structural unit represented
by the formula (I), that has a structure having one terminal represented
20 by the foirnula (4) and the other terminal represented by the formula (6),
and for which, in the formula (I), R', R2, and R3 are each a hydrogen
atom, m is an integer of 0 to 4, R4 is a divalent hydrocarbon group
having 2 to 4 carbon atoms, and RS is a hydrocarbon group having 1 to
20 carbon atoms.
(c) A polyvinyl ether that has a st~~lctuhreav ing one terminal
represented by the formula (4) or (5) and the other tenninal represented
by the formula (8) and for which, in the fornlula (I), R', R2, and R~ are
each a hydrogen atom, m is an integer of 0 to 4, R4 is a divalent
5 hydrocarbon group having 2 to 4 carbon atoms, and R' is a hydrocarbon
group having 1 to 20 carbon atoms.
(d) Apolyvinyl ether that has only the structural unit represented
by the formula (I), that has a structure having one terminal represented
by the formula (5) and the other tenninal represented by the formula (8)
10 and for which, in the formula (I), R', R2, and R3 are each a hydrogen
atom, m is an integer of 0 to 4, R4 is a divalent hydrocarbon group
having 2 to 4 carbon atoms, and R' is a hydrocarbon group having 1 to
20 carbon atoms.
(e) A polyvinyl ether that corresponds to any one of the above
15 (a), (b), (c), and (d) and that has a structural unit represented by the
formula (1) where R5 is a hydrocarbon group having 1 to 3 carbon
atoms and a struct~~ruanl it represented by the formula (1) where R' is a
hydrocarbon group having 3 to 20 carbon atoms.
[0066] A side reaction nlay occur during the production process of the
20 polyvinyl ether to cause an unsaturated group such as an a171 group to
be formed in the molecule, and, in terms of improvement in the thermal
stability of the polyvinyl ether itself, prevention of sludge generation
caused by polymer formation, and prevention of peroxide formation
caused by deterioration in antioxidative properties (oxidation inhibiting
25 properties), a polyvinyl ether having a low degree of unsaturation
derived kom an unsaturated group or the like is preferred as the
polyvinyl ethec It is preferable that the degree of unsaturation of the
polyvinyl ether be 0.04 ueq/g or less, more preferably 0.03 meq/g or
less, even more preferably 0.02 meq/g or less. It is preferable that the
peroxide value of the polyvinyl ether be 10.0 meqfkg or less, more
5 preferably 5.0 nleqkg or less, even more preferably 1.0 meqkg. It is
preferable that the carbonyl value of the polyviuyl ether be 100 ppln by
weight or less, more preferably 50 pptn by weight or less, even more
preferably 20 ppm by weight or less. It is preferable that the hydroxyl
value of the polyvinyl ether be 10 mgKOWg or less, more preferably 5
10 mgKOI1/g or less, even more preferably 3 mgKOI1g or less.
[0067] The degree of unsaturation, peroxide value, and carbonyl value
in the present invention refer to values measured by the JOCS Standard
Methods for the Analysis of Fats, Oils and Related Materials specified
by Japan Oil Chemists' Society. That is, the degree of unsaturation in
15 the present invention refers to a value (meqlg) determined as follows: A
Wijs solution (acetic acid solution of ICl) is reacted with a sample,
which is then left in a dark place; excess ICI was subsequently reduced
to iodine; the iodine was titrated with sodium thiosulfate to calculate an
iodine value; and this iodine value was converted to a vinyl equivalent.
20 The peroxide value in the present invention refers to a value (meqfkg)
determined as follo~~Pso: tassium iodide is added to a saniplc; the
resulting free iodine was titrated with sodium thiosulfate; and the
amount of the free iodine is converted to a milliequivalent relative to 1
kg of the sample. The carbonyl value in the present invention refers to
25 a value (ppm by weight) determined as follows:
2,4-dinitrophenylhydrazine was reacted with a sample to produce
color-folining quinoid ions; the absorbance of the sample at 480 11111 was
~neasured; and the amount of the quinoid ions was converted to a
carbonyl content on' the basis of a calib~ation curve determined
beforehand using cinnamaldehyde as a reference material. The
5 hydroxyl value iu the present invention refers to a hydroxyl value
measured according to J1S K 0070: 1992.
[0068] The polyalkylene glycol may have various chemical structures,
and examples of typical colnpounds include polyethylene glycol,
polypropylene glycol, and polybutylene glycol. The unit structure of
10 the polyalkylene glycol is oxyethylene, oxypropylene, or oxybutylene.
Polyalkylene glycols having these unit structures can be obtained by
ring-opening polymerization using the monomers, ethylene oxide,
propylene oxide, and butylene oxide, respectively, as raw materials.
[0069] Examples of the polyalkylene glycol include compounds
15 represented by the following formula (9).
R~-[(OR~)~OR~], (9)
[In the formula (I), Ra represents a hydrogen atom, an allcyl
group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon
atoms, or a residue of a compound having 2 to 8 hydroxyl groups,
20 represents an alkylene group having 2 to 4 carbon atoms, RY represents a
hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl
group having 2 to 10 carbon atoms, f represents an integer of 1 to 80,
and g represents an integer of I to 8.1
[0070] In the formula (9), the alkyl group represented by Ra or RY may
25 be linear, branched, or cyclic. The number of carbon atoms in the
alkyl group is preferably 1 to 10 and more preferably 1 to 6. If the
number of carbon atoms in the alkyl group is more than 10, the
compatibility with refrigerants tends to decrease.
[0071] The alkyl moiety of the acyl group represented by Ra or R' may
be lineal; branched, or cyclic. The number of carbon atoms in the acyl
5 group is preferably 2 to 10 and more preferably 2 to 6. If the number
of carbon atoms in the acyl group is more than 10, the compatibility
with reffigerants may decrease, which may cause phase separation.
[0072] When both of the groups represented by Ra and RY are aajkyl
goups or acyl groups, the groups represented by Ra and R7 may be the
10 same or different. When g is 2 or more, the two or more groups
represented by Ru or Rr in the same molecule may be the same or
different.
[0073] When the group represented by Ru is a rcsidue of a compound
having 2 to 8 hydroxyl groups, this compound may be linear or cyclic.
15 [0074] For the polyalkylene glycol represented by the above folrnula
(9), it is preferable that at least one of Ra and R7 be an alkyl group
(more preferably an alkyl group having 1 to 4 carbon atoms), and it is
particularly preferable that at least one of RU and Rr be a methyl group,
in terms of the compatibility with rekigerants.
20 [0075] In terms of tl~ermala nd chemical stability, it is preferable that
both of Ru and R' be alkyl groups (more preferably alkyl groups having
1 to 4 carbon atoms), and it is more preferable that both of Ru and RY be
a methyl group.
[0076] In terms of ease of production and cost, it is preferable that one
25 of R" and R7 be an alkyl group (more preferably an alkyl group having 1
to 4 carbon atoms) and the other be a hydrogen atom, and it is inore
preferable that one of RU and 1<( be a methyl group and the other be a
hydrogen atom. In terms of lubricating propelties and sludge
dissolving propesties, it is preferable that both of Ru and RY be a
hydrogen atom.
5 [0077] RO in the above fortnula (9) represents an alkylene group having
2 to 4 carbon atoms, and specific examples of such an alkylene group
include an ethylene group, a propylene group, arid a butylene group.
Examples of the oxyalkylene group represented by ORO include an
oxyethylene group, an oxypropylenc group, and an oxybutylene group.
10 The polyoxyalkylene group represented by ( 0 ~m~ay )be ~con stituted
by one type of oxyalkylene group or may be constituted by two or riiore
types of oxyalkylene groups.
[0078] Among polyalkylene glycols represented by the above formula
(9), a copolymer containing an oxyethylene group @0) and an
15 oxypropylene group (PO) is preferred in terms of compatibility with
refrigerants and viscosity-temperature characteristicsi In this case, it is
preferable that the proportion of the oxyethylene group in the total of
the oxyethylene group and oxypropylene group (EOI(P0 + EO)) be in
the range of 0.1 to 0.8, more preferably in the range of 0.3 to 0.6, in
20 terms of seizure load and viscosity-temperature characteristics.
[0079] 111 teims of hygroscopic properties or thermal and oxidative
stability, it is preferable that EO/(PO + EO) be ip the range of 0 to 0.5,
more preferably in the range of 0 to 0.2, no st preferably 0 (i.e.,
propylene oxide hotnopoly~ner).
25 [0080] f in the above formula (9) represents the number of repeating
oxyalkylene groups OR' (degree of polymerization) and is an integer of
1 to 80. g is an integer of 1 to 8. For example, when RE is an alkyl
group or an acyl group, g is 1. When RU is a residue of a coinpound
having 2 to 8 hydroxyl groups, g corresponds to the number of hydroxyl
groups that the colnpound has.
5 [0081] The product of F and g (f x g) is not pa~ticulaslyli mited, but it is
preferable that the average of values off x g be 6 to 80 in order to
achieve the above various properties required of the reeigerating
machine oil in a well-balanced manner.
[0082] The number average molecular weight of the polyalkylene
10 glycol represented by the formula (9) is preferably 500 or inare and
more preferably 600 or more and is preferably 3000 or less, more
preferably 2000 or less, and even more preferably 1500 or less. It is
preferable for f and g in the formula (9) to be such numbers that the
number average inolecular weight of the polyalkylene glycol meets the
15 above requirement. If the number average molecular weight of the
polyalkylene glycol is too low, the lubricating properties in the presence
of a refrigerant are insufficient. If the nuinber average molecular
weight is too high, the coinposition range over which compatibility is
exhibited for refrigerants at low temperatures is narrow, and poor
20 lubrication of a refrigerant compressor or inhibition of heat exchange in
an evaporator is likely to occur.
[0083] The hydroxyl value of the polyalkylene glycol is, but not limited
to, 100 mgKOWg or less, preferably 50 mgKOH/g or less, more
preferably 30 mgKOH1g or less, most preferably 10 mgKOH/g or less.
25 [0084] The polyalkylene glycol can be synthesized using a
commo~ily-known method ("Alkyleneoxide Polymer", Mitsuta Slibata
et al,, KAIBUNDO, issued on November 20, 1990). For example, the
polyalkylene glycol represented by the above fornlula (9) is obtained by
allowing one or inore types of specified alkylene oxides to undergo
addition-polymerization with an alcohol (RaOH; RU represents the same
5 as defmed for RU in the above fornlnla (9)) and fi~l-there therifying or
esterifying the terminal hydroxyl group. When two or more types of
alkylene oxides are used in the above production process, the resulting
polyallcylene glycol may be either a randon] copolynler or a block
copoiymer, and it is preferable for the polyalkylene glycol to be a block
10 copolynler in terms of better oxidative stability and lubricating
properties, while in terns of better low-temperature fluidity, it is
preferable for the polyalkylene glycol to be a random copolymer.
[0085] The kinematic viscosity of the polyalkylene glycol at 100°C is
preferably 5 d s or more, more preferably 6 mm2/s or more, even
15 more preferably 7 m2/s or more, particularly preferably 8 mm2/s or
more, and most preferably 10 mm2/s or more and is preferably 20 m 2 / s
or less, more preferably 18 m&s or less, even more preferably 16
mm2/s or less, and parliculasly preferably 15 mm2/s or less. If the
kinematic viscosity at 100°C is less than the lower limit, the lubricating
20 properties in the presence of a refrigesant are insufficient, while if the
upper limit is exceeded, the composition range over which compatibility
is exhibited for refrigerants is narrow, and poor lubrication of a
refrigerant compressor or inhibition of heat exchange in an evaporator is
likely to occur. The kinematic viscosity of the polyalkylene glycol at
25 40°C is preferably 10 mm2/s or more and more preferably 20 mm2/s or
more and is preferably 200 mm2/s or less and more preferably 150
md/s or less. If the kinematic viscosity at 40°C is less than 10 mmn2/s,
the lubricating properties or the hermeticity of a compressor are likely
to deteriorate, while if 200 mmn2/s is exceeded, the colllposition range
over wllicll colllpatibility is exhibited for regigexants at low
5 temperatures is narrow, and poor lubrication of a refrigerant compressor
or inhibition of heat exchange in an evaporator is likely to occur.
[0086] The pour point of the polyalkylene glycol is preferably -10°C or
lower and more preferably -20°C or lower and is preferably -50°C or
higher. If a polyalkylene glycol with a pour point higher than -10°C is
10 used, the refrigerating machine oil is likely to solidify at a low
temperature in a refrigerant circulation system. The pour point in the
present invention refers to a pour point specified in KIS K 2269.
[0087] During the production process of the polyalkylene glycol
represented by the above formula (9), an alkyleneoxide such as
15 propylene oxide may undergo a side reaction to form an unsaturated
group such as an alyI group in tlie molecule. If an unsaturated group is
formed in the polyalkylene glycol molecule, the following phenomena
are likely to occur: the thermal stability of the polyalkylene glycol itself
is reduced; a poly~ner is produced to cause generation of sludge; and
20 antioxidative propelties (oxidation inhibiting properties) deteriorate to
cause formation of a peroxide. In particular, if a peroxide is formed,
the peroxide is deconposed to form a conlpound having a carbonyl
group, and the colnpound having a carbonyl group will generate sludge,
so that capillary clogging is likely to occur.
25 [0088] Thus, a polyalkylene glycol having a low degree of unsaturation
derived fiom an unsaturated group or the like is preferred as the
polyalkylene glycol. It is preferable that the dcgree of unsaturation of
the polyalkylene glycol be 0.04 meqlg or less, more preferably 0.03
meqlg or less, even more preferably 0.02 meqlg or less. It is preferable
that thc peroxide value be 10.0 meqkg or less, more preferably 5.0
5 meqkg or less, even more preferably 1.0 meq/kg. It is preferable that
the carbonyl value be 100 ppm by weight or less, more preferably 50
ppln by weight or less, even more preferably 20 ppm by weight or less.
[0089] To obtain a polyalkylene glycol having a low degree of
unsaturation, a low peroxide value, and a low carbonyl value, the
10 reaction temperature during reaction of propylene oxide is preferably
120°C or less and more preferably llO°C or less. If an alkali catalyst
is used in production, the use of an inorganic adsorbent, such as
activated carbon, activated white earth, bentonite, dolomite, or
aluminosilicate, for removing the catalyst can reduce the degree of
15 unsatutation. Increase in peroxide value or carbonyl value can be
prevented also by adding an antioxidant or avoiding contact with
oxygen as much as possible duiing production or use of the
polyalkylene glycol.
[0090] The polyalkylene glycol needs to have a carbontoxygen molar
20 ratio within a predetermined range. A polymer having the molar ratio
within the range can be produced by selecting and adjusting the types
and mixing ratio of the monomers as raw materials. ,
[0091] The base oil may fbrther contain, for example, a mineral oil or a
hydrocarbon oil such as an olefin polymer, a naphthalene compound, or
25 an alkylbenzene, in addition to the above oxygen-containing oil. It is
preferable that the content of the above oxygen-containing oil be 5
mass% or more, Inore preferably 30 mass% or more, even Inore
preferably 95 mass% or more, with respect to the total amount of the
base oil.
[0092] The refrigerating machine oil may further contain various
5 additives where necessary. Examples of such additives include an acid
scavenger, an oxidation inhibitor, an exqreme-pressure agent, an oily
agent, an anti-foaming agent, a metal deactivator, an anti-wear agent, a
viscosity index improver, a pour point depressant, and a detergent
dispersant. It is preferable that the content of the additive be 5 mass%
10 or less, more preferably 2 mass% or less, with respect to the total
amount of the rekigerating machitie oil.
[0093] It is preferable for the refiigerating machine oil to fiu2her
contain an acid scavenger anlong the above additives, in terms of fulther
improving the thermal and chemical stability. Examples of the acid
15 scavenger include an epoxy compound and a carbodiimide compound.
[0094] Examples of the epoxy compound include, but are not limited
to, a glycidyl ether epoxy conlpound, a glycidyl ester epoxy compound,
an oxirane compound, an alkyloxirane compound, an alicyclic epoxy
compound, an epoxidized fatty acid monoester, and an epoxidized
20 vegetable oil. One of these epoxy compounds may be used alone or
two or more thereof may be used in combination.
[0095] Exa~nples of tlie glycidyl ether epoxy compound include
n-butylphenyl glycidyl ether, i-butylphenyl glycidyl ether,
sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether,
25 pentylphenyl glycidyl ether, hexylphenyl glycidyl ether, heptylphenyl
glycidyl ether, octylphenyl glycidyl ether, nonylphenyl glycidyl ether,
decylplie~lygl lycidyl ether, decyl glycidyl ether, undecyl glycidyl ether,
dodecyl glycidyl ether, tridecyl glycidyl ethel; tetradecyl glycidyl ether,
2-ethylhexyl glycidyl ether, neopentyl glycol diglycidyl ether,
trimetl~ylolpropane triglycidyl ether, pentaeiythritol tetraglycidyl.
5 ether,l,6-hexatiediol diglycidyl ether, sorbitol polyglycidyl ether,
polyalkylene glycol inonogl~~cidyelt her, and polyalkylene glycol
diglycidyl ether.
[0096] Examples of the glycidyl ester epoxy colnpound include
glycidyl benzoate, glycidyl neodecanoate, glycidyl-2,2-
10 dimethyloctanoate, glycidyl ac~ylatea, nd glycidyl methacrylate.
[0097] The alicyclic epoxy compound is a compound having a partial
structure in which carbon atoms included in an epoxy group are
included as such in the alicyclic ring, the compound being represented
by the following for~nula(1 0).
15 [Chemical Formula 111
[0098] Exatnples of the alicyclic epoxy compound include
1,2-epoxycyclohexane, 1,2-epoxycyclopentane,
3',4'-epoxycyclol~exyl~nethyl-3,4-epoxycyclohexanecarboxy~ate,
20 bis(3,4-epoxycyclohexyllnethyl) adipate, exo-2,3-epoxynorbornane,
bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate,
2-(7-oxabicyclo[4.1.0]hepto-3-yl)-spiro(l,3-dioxane-5,3'-[7]oxabicyclo[
4.1 .O]heptane, 4-(1'-methylepoxyethyl)-1,2-epoxy-2-
methylcyclohexane, and 4-epoxyethyl-l,2-epoxycycIol~exane.
8 1
f00991 Examples of the atyloxirarie compound include I
1,2-epoxystyrene and alkyl-1,2-cpoxystyrene.
[0100]Exanlples of the alkyloxirane compound include 1
1 ,2-epoxybutane, 1,2-epoxypenta1le, 1,2-epoxyhexane, 1!
5 t ,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 1I
1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, I 1 :
1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1
1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,1,2-epoxyoctadecane,
2-epoxynonadecane, and 1,2-epoxyeicosane.
10 [0101] Examples of the epoxidized fatty acid rno~ioesteri nclude an
ester of an epoxidized fatty acid having 12 to 20 carbon atoms with an
alcohol having 1 to 8 carbon atoms, phenol, or an alkylphenol. As the
epoxidized fatty acid monoester there are preferably used esters of
! epoxystearic acid with butyl, hexyl, benzyl, cyclohexyl, methoxyethyl,
i
15 octyl, phenyl, and butylphenyl. i
I
1 [0102] Exan~ples of the epoxidized vegetable oil include epoxy I
compounds of vegetable oils such as soybean oil, linseed oil, and
cottonseed oil.
[0103] The casbodiimide colnpound is not particularly limited and, for
20 example, dialkylcarbodiimide, diphenylcarbodiimide, and
bis(allcylpheny1)carbodiimide can be used. Examples of the
dialkylcarbodiimide iuclude dusopropylca~bodiimide and
dicyclohexylcarbodiimidc. Examples of the
bis(alkylpheny1)carbodiimide include ditolylcarbodii~nide,
25 bis(isopropylphenyl)carbodiimide, bis(diisopropylphenyl)carbodiimide,
bis(tsiisopropylphenyl)carbodiimide, bis(butylphenyl)carbodiimide,
bis(dibutylphenyl)carbodiin~ide, and bis(nonylp1~enyl)carbodiimide.
[0104] In order for the refrigerathg machine oil to be superior in the
properties required of the refrigerating machine oil such as lubricating
properties, compatibility, thermal and chemical stability, and electrical
insulating properties, it is preferable that the content of the base oil in
the refrigerating machine oil be 80 mass% or more, more preferably 90
mass% or more, even more preferably 95 mass% or more, with respect
to the total amount of the refrigerating machine oil.
[0105] The kinematic viscosity of the refrigerating machine oil at 40°C
may be preferably 3 mm2/s or more, more preferably 4 mm2/s or more
and even more preferably 5 mn2/s or more and may be preferably 1000
mm2/s or less, more preferably 500 mm2/s or less, and even more
preferably 400 mm2/s or less. The kinematic viscosity of the
refkigerating machine oil at 100°C may be preferably 1 d s or more
and more preferably 2 mm2/s or more and may be preferably 100 m 2 / s
or less and more preferably 50 md/s or less.
[0106] The volume resistivity of the i~i7igerating machine oil is not
particularly limited, but may be preferably 1.0 x lo9 C2.m or more, more
preferably 1.0 x 10'' 0.m or more, and even more preferably 1.0 x 10''
C2.m or more. Good electrical insubating properties are often needed,
in particular, for use in a hermetic refrigerating machine. The volume
resistivity in the present invention refers to a volutue resistivity at 25°C
measured according to JIS C 2101 "Testing methods of electrical
insulating oils".
[0107] The moisture content of the refrigerating machine oil is not
particularly limited, but is preferably 200 ppm or less, more preferably
100 ppm or less, and even morc preferably 50 ppm or less, with respect
to the total amount of the refiigerating machine oil. It is required that
the inoisture content be low, in particular, for use in a hermetic
refrigerating machine, in terms of influence on the thermal and chemical
5 stability and electrical insulating properties of the refrigerating machine
oil.
[0108] The acid value of the refrigerating machine oil is not paiticu~larly
limited, but may be preferably 0.1 mgKOH/g or less and more
preferably 0.05 mgKOWg or less, in order to prevent the corrosion of
10 metals used in the rei5igerating machine or pipes and prevent the
decomposition of the ester contained in the rehigerating machine oil
according to the present embodiment. The acid value in the present
invention refers to an acid value measured according to JIS K 2501
"Petroleum products and lubricants-Determination of neutralization
15 number".
[0109] The ash content of the refrigerating machine oil is not
palticularly limited, but may be preferably 100 ppm or less and more
preferably 50 ppm or less in order to increase the thermal and chemical
stability of the refiigerating machine oil and thus reduce the generation
20 of sludge or the like. The ash content in the present invention refers to
an ash content measured according to JIS K 2272 "Crude oil and
petroleum products-Determination of ash and sulfated ash".
[0110] The pour point of the refrigerating maclline oil may be
preferably -lO°C or lower, more preferably -20°C or lower, and even
25 more preferably -30°C or lower. The pour point in the present
iuvention refers to a pour poiut measured according to JIS K 2269.
1
FP14-0664-00 I
[Ol 1 11 The refrigerating machine oil accorditlg to the present
embodiment is used with a trifluoroethylene (HFO-1123) refi'igerant.
The workiug fluid composition for a refrigerating machine according to
the present embodiment comprises a trifluorocthylcnc (KFO-1123)
5 refrigerant.
101121 That is, a composition containing at least one oxygen-containing
oil having a carbonfoxygen molar ratio of 2.5 or more and 5.8 or less is
suitably used as a component of a refrigerating machine oil used with a
trifluoroethylene refrigerant or as a component of a working fluid
10 composition for a refrigerating machine containing a refrigerating
machie oil and a trifluoroethylene refrigerant.
[0113] The composition containing at least one oxygen-containing oil
having a carbodoxygen molar ratio of 2.5 or more and 5.8 or less is
suitably used for manufacturing a refrigerating machine oil used with a
15 trifluoroethylene refrigerant or for manufacturing a working fluid
composition for a refrigerating machine containing a refrigerating
machie oil and a trifluoroethylene refrigerant.
[0114] The refrigerant used with the refrigerating machine oil
according to the present embodiment and the rekigerant contained in
20 the working fluid cornposition for a refrigeratiug machine according to
the present embodiment may further contain, in addition to
trifluoroethylene (WO-1123), a co~mnonly-knownre frigerant such as a
saturated hydrofluorocarbon refrigerant or unsaturated
hydrofluorocarbon refrigerant. In terms of the stability of the
25 rekigerating machine oil in a refrigerant environment, it is preferable
that the content of trifluoroethylene (HFO-1123) be 90 mass% or less,
more preferably 60 mass% or less, even more preferably 50 mass% or
less, particularly preferably 40 mass% or less, most preferably 20
mass% or less, with respect to the total amount of the refrigerant. In
terms of reductioti in GWP, it is preferable that the content of
5 kifluoroethylene (FIFO-1 123) be 20 mass% or more, more preferably 40
mass% or more, even more preferably 50 mass% or more, particularly
preferably 60 mass% or more, most preferably 90 mass% or m e , with
respect to the total amount of the refrigerant.
[0115] Examples of the saturated hydrofluorocarbon refrigerant include
10 one, or a mixture of two or more, selected Grom the group consisting of
difluoromethane (HFC-32), pentafluoroethane (HFC-125),
1,1,2,2-tetrafluoroethane WC-134), 1,1,1,2-tetrafluoroethane
(HFC-134a), 1,l-difluoroetl~ane (WC-152a), fluoroethane (HFC-161),
1,1,1,2,3,3,3-heptafluoropropane WC-227ea), 1,1,1,2,3,3- I
15 hexafluoropropane (HFC-236ea), 1,1,1,3,3,3-hexafluoropropanc
(HFC-236fa), 1,1,1,3,3-penta£luoropropane (HFC-245fa), and 1,1,1,3,3-
pentafluorobutane (HFC-365mfc). Among these, difluoromethane
(HFC-32) and 1,1,1,2-tetrafluoroethane (HFC-134a) are preferred in
terms of the stability of the refitgcrating machine oil in a refi-igerant
20 environment and reduction in GJW.
[0116] Examples of the unsaturated hydrofluorocarbon refrigerant
iuclude one, or a mixture of two or more, selected fi-on1 the group
consisting of 1,2,3,3,3-pentafluoropsopene m0-1225ye), 1,3,3,3-
tetrafluoropropene @PO-1234ze), 2,3,3,3-tetrafluoropropene
25 (HFO-1234yl), 1,2,3,3-tetrafluoropropene (HFO-1234ye), and
3,3,3-trifluoroprope~le (HFO-124329. Among these, 2,3,3,3-
tetrafluoropropene (HFO-1234yf) is preferred in terms of the stability of
the refiigerating machine oil in a refrigerant environment and reduction
in GUT.
[0117] The content of the refiigerating machine oil in the working fluid
5 composition for a refrigerating machine is not particularly limited, but
may be preferably 1 part by mass or more and more preferably 2 parts
by mass or more and may be preferably 500 parts by Illass or less and
more preferably 400 parts by mass or less, per 100 parts by mass of the
refrigerant.
10 [0118] The working fluid composition for a refrigerating ~nachine
according to the present embodiment is preferably used in: room air
conditioners having a reciprocating or rotary hermetic compressor;
refrigerating chambers; and open-type or hermetic-type car air
conditioners. The working fluid composition for a refrigerating
15 machine and refrigerating machine oil according to the present
embodiment are preferably used, for example, in dehumidifiers, water
heaters, freezers, freezinglrefrigerating warehouses, vending machines,
showcases, and cooling systems of chemical plants etc. In addition,
the working fluid composition for a refrigerating machine and
20 refrigerating machine oil according to the present embodiment are
preferably used also in apparatuses having a centrifugal compressor.
Examples
[0119] Hereinafter, the present invention will be more specifically
described by way of examples; however, the present invention is not
25 limited to the exa~nplesd escribed below.
[0120] Polyol esters of fatty acids having compositions shown in Table
1 with a poiyhydric alcohol were prepared as base oils 1 to 6. The
abbreviations in the table denote the following conlpounds.
iC4: 2-methylpropanoic acid
nC5: n-pentanoic acid
iC8: 2-ethylhexanoic acid
iC9: 3,5,5-trimnethylhexanoic acid
nC10: n-decanoic acid
iC 18: 2-ethylhexadecanoic acid
PET Pentae~ythritol
10 [0121] [Table I]
- -
- -
PET PET
Base oil Base oil 5
PET PET
Base oil
5
-
PET PET
LO1221 Sample oils 1 to 7 having cornpositio~ish ow11 in Table 2 were
prepared using the base oils I to 6 and the additives listed below.
Additive 1 : Glycidyl neodecanoate
Additive 2: 2-ethylhexyl glycidyl ether
Additive 3: Bis(diisopropylpheny1)carbodiimide
Additive 4: Diisopropylcarbodiimide
[0123] The stability test describcd hereinafter was conducted on each
sample oil. The res~11tsa re shown in Table 2.
[0124] (Stability test)
The stability test was conducted according to JIS K 2211-09
(autoclave test). Specifically, 80 g of each sample oil whose moisture
content was adjusted to 100 ppm was weighed into an autoclave, inside
which were placed catalysts (iron, copper, and aluminum wires, all of
which had a size of 1.6 nun outer diameter x 50 mm length) and 20 g of
any one refkigerant mixture selected from the refrigerant mixtx~resA to
C listed below. This was followed by heating to 140°C and, after 150
hours, the acid value (JIS C 2101) of the sample oil was measured.
Refrigerant mixture A: Refrigerant mixture of
2,3,3,3 -tetrafluoropropene (I-IFO- 1234yf) and trifluoroethylene
(HFO-1123) (Mass ratio (HFO-1234flHF'O-1123) = 80120)
Refrigerant mixture B: Refrigerant mixture of difluoromethane
(I-IFC-32) and trifluoroethylene (tni0-1123) (Mass ratio
(HFC-32/HFO-1123) = 40160)
Refrigerant mixture C: Refrigerant mixture of
1,1,1,2-tetrafluoroethane (HFC-134a) and trifluoroethylene (HFO-1123)
(Mass ratio (HFC-134a/HFO-1123) = 20/80)
[0125] [Table 21
[0126] In addition, the refrigerant compatibility test described below
was conducted on the sample oils 1 to 5, and it was confilmed that all of
the sample oils were compatible with the refiigerants.
5 [0127] (Refiigeratit compatibility test)
An amount of 10 g of each sample oil was mixed with 10 g of
each of the refrigerant mixtures A to C according to "Testing method for
conlpatibility with refiigerants" specified in JIS-I< 2211 "Refrigerating
machine oils" to observe whether the refrigerant and the refrigerating
10 nlachine oil were dissolved in each other at O°C.

CLAIMS
1. A rekigerating machine oil comprising at least one
oxygen-containing oil having a carbon/oxygen molar ratio of 2.5 or
more and 5.8 or less as a base oil, and the refiigerating machine oil
5 being used with a trifluoroethylene refrigerant.
2. The refrigerating machine oil according to claim 1, comprising
an ester of a fatty acid and a polyhydric alcohol as the
oxygen-containing oil, the fatty acid comprising a branched fatty acid
having 4 to 9 carbon atoms in apropoltion of 20 to 100 mol%.
10 3. A working fluid composition for a refrigerating machine
comprising:
a refrigerating machine oil comprising at least one
oxygen-containing oil having a carbonloxygen molar ratio of 2.5 or
more and 5.8 or less as a base oil; and
15 a trifluoroethylene refrigerant.
4. The working fluid composition for a refrigerating machine
according to claim 3, wherein the refiigerating machine oil comprises
an ester of a fatty acid and a polyhydric alcohol as the
oxygen-containing oil, the fatty acid comprising a branched fatty acid
20 having 4 to 9 ca~bonat oms in a proportion of 20 to 100 mol%.
5. Use of a composition for a refrigerating machine oil or a
working fluid composition for a refiigerating machine, the composition
conlprising at least one oxygen-containing oil having a carbodoxygen
molar ratio of 2.5 or more and 5.8 or less,
25 the refrigerating machine oil being used with a trifluoroethylene
refrigerant,
the working fluid composition for a rehigerating machine
cornpsising the refrigerating machine oil and a trifluoroethylene
refiigerant.
6. Use of a comnposition for ~nanufacturinga refrigerating machine
oil or a working fluid composition for a reeigerating machine, the
composition comprising at least one oxygen-containing oil having a
carbonloxygen molar ratio of 2.5 or more and 5.8 or less,
the refrigerating machine oil being used with a trifluoroethylene
reftigerant,
the working fluid composition for a refkigerating machine
comprising the refrigerating machine oil and a trifluoroethylene
refiigerant.