DESClRIPTION
Title of Invention: WORKING FLUID COMPOSITION FOR
REFRIGERATOR
Technical Field
5 [0001] The present invention relates to a working fluid composition for
a refrigerating machine, and more specifically relates to a working fluid
composition for a refrigerating machine that contains a refrigerant
which contains monofluoroethane (also referred to as "HFC-161" or
"R1611').
10 Background Art
[0002] CFC (chlorofluorocarbon) and HCFC
(hydrochlorofluorocarbon), which have been conventionally used as
refrigerants for refiigeration equipment, have been subject to regulation
due to the problem of recent ozone depletion, and HFC
15 (hydrofluorocarbon) has come to be used as a refsigerant instead of
them.
[0003] Among HFC refrigerants, HFC-134a, R407C, and R410A are
normally used as refrigerants for car air-conditioners, cold storage
chambers, or room air-conditioner. Although the ozone depletion
20 potential (ODP) of these HFC refrigerant is zero, these come to be
subject to regulation, because the global warming potential (GWP)
thereof is high. While difluoromethane has becn studied as one of
alternate candidates of these refrigerants, difluoromethane has the
following problems: the global warming potential thereof is not
25 sufficiently low; the boiling point thereof is so low that thermodynamic
characteristics cannot be applied to a current refiigeration system
directly; and difluoromethane is not easily compatible with lubricating
oils (refrigerating machine oils) used for conventional HFC refrigerants,
such as polyol esters and polyvinyl ethers. On the other hand,
unsaturated hydrofluorocarbons have been proposed to be used as a
5 refrigerant due to the following reasons; both of its ODP and GWP are
very low; unsaturated hydrofluorocarbons are non-flammable
depending on structures; and in particular with respect to HFO-1234yf,
thermodynamic characteristics as measures of refrigerant perfo~mances
are comparable with or better than those of HFC-134a (Patent
10 Literatures 1 to 3).
[0004] In addition, a working medium including 80% by mass or more
of one or more first components selected fiom 1,l-difluoroethane
(HFC- 152a), 1,1,1-trifluoro-2-monofluoroethane (HFC-134a) and
l,l,l-trifluoro-2,2-difluoroethane (HFC-125) as first components, and
15 20% by mass or less of carbon dioxide (R744) as a second component
has been proposed (Patent Literature 4).
[0005] Hydrocarbons such as isobutane (R600a) and propane (R290)
that are flammable, in which the ODP is 0 and the GIW is as extremely
low as about 3, have also been studied (Patent Literatures 5 to 7).
20 Citation List
Patent Literature
[0006] [Patent Literature 11 International Publication WO20041037913
[Patent Literature 21 International Publication WO20051105947
patent Literature 31 International Publication W020091057475
25 patent Literature 41 Japanese Patent Application Laid-Open No.
10-265771
[Patent Literature 51 Japanese Patent Application Laid-Open No.
2000-044937
patent Literature 61 Japanese Patent Application Laid-Open No.
2000-274360
5 patent Literature 71 Japanese Patent Application Laid-Open No.
2010-03 1728
Summary of Invention
Technical Problem
[0007] An object in a refkigeration/air-conditioning system is to find out
10 a working fluid satisfying all of the following many characteristics: with
respect to a refrigerant, adverse influences on the environment are small
due to a low global warming potential (GWP), use with safety is
possible because burning and explosion hardly occur, thermodynamics
characteristics are suitable for applications, and large-scale supply is
15 possible because the chemical structure is simple; and with respect to
characteristics in the system where a refrigerant and a refkigerating
i machine oil coexist, they are soluble in each other (compatibility) and j
are excellent in stability, and an oil film that is not worn is maintained
(lubricity).
20 [0008] As the next-&neration low-GWP refrigerant instead of the
1 current high-GWF' HFC refkigerant, HFC-32 (GWP: 675), HFO-1234yf
(GWP: 4), HFC-152a (GWP: 120), and propane (R290, GWP: 3) are
studied as major candidates, as described above, but each of them is
problematic.
25 [0009] In the refrigerant circulation cycle of
I
! refrigerationlair-conditioning equipment, since a seffigerating machine
FP12-0800-00
oil for lubricating a refrigerant compressor circulates together with a
refiigerant in the cycle, the refifgerating machime oil is demanded to be
compatible with the refrigerant. In the refrigeratiodair-conditioning
system using HFC-32, however, a problem is that HFC-32 is hardly
5 compatible with the refrigerating machine oil. In the
refrigerationlair-conditioning equipment, sufficient compatibility
between the reeigerant and the refrigerating machine oil is not achieved
depending on the selection of the refiigerating machine oil used with the
refrigerant, and the refrigerating machine oil discharged from the i
!10 refrigerant compressor easily remains at a place where the temperature
is low in the cycle. As a result, there occur the problems of wear due
to lubrication failure by the reduction in amount of the oil in the
refrigerant compressor and of blockage of an expansion mechanism i I:
such as a capillary that is a narrow tube whose inner diameter is 1 mrn 1!::<
15 or less. In addition, there is also the following problems about
thermodynamics characteristics: because the boiling point of HFC-32 is
-52°C and is lower than that of the current refiigerant, HCFC-22, used
for room air-conditioners, all-in-one air conditioners, and the like by
about 1 O°C, the pressure is higher at the same temperature and thus the
20 discharge temperature is excessively increased; and furthermore,' the
GWP thereof is 675 and thus is not sufficiently low.
[0010] In the refrigeratiodair-conditioning system using HFO-1234yf
being an unsaturated hydrofluorocarbon, whose C-WP is also extremely
low, it has been considered that HFO-1234yf is compatible with the
25 reKgerating machine oil such as polyol esters and an ether compound
used for the current HFC, and thus is applicable. According to the
studies by the present inventors, however, the following problem about
stability has been revealed: unsaturated hydrofluorocarbons have
-unstable double bonds in their molecules and thus are poor in
thermaWchemica1 stability. In addition, HFO-1234yf, whose boiling
5 point is -25"C, cgn be applied in the fields of a car air-conditioner and a
coolerator in which HFC-134a whose boiling point is -26°C is used, but
cannot be applied in the fields of a room air-conditioner, an all-in-one
air conditioner, an industrial refrigerating machine, and the like in which
I-ICFC-22 whose boiling point is -41°C and whose pressure is relatively
10 high is used and the amount of the refrigerant used is large, because
efficiency is too low.
[0011] HFC-152% whose GWP is also low, is a well-balanced
refrigerant in terms of charactexistics, but is flammable. HFC-152a,
whose boiling point is -2S°C, however, can be applied only in the field
15 of HFC-134a due to thermodynamics characteristics thereof. In the
coolerator field, in which the amount of the refiigerant charged is small,
among main fields in which HFC-134a is used, switching to isobutane
@600a) whose GWP is as low as 3 has already progressed. Isobutane,
however, also has the problem of incapable of being applied to
20 applications in which the amount of the refiigesant charged is small, in
terms of thermodynamics characteristics and safety.
[0012] Propane, whose boiling point is -42°C and whose GWP is also
extremely low, is excellent in refrigerant characteristics in the field in
which HCFC-22, or as an alternate thereof, R410A that is a mixed
25 refrigerant where the ODP is 0 and HFC-32 and HFC-125 are each
present in 50% by mass is used. Propane, however, is highly
flammable and also high in explosibility, and has the problem of safety.
[0013] In the case of the refligerant as described in Patent Literature 4,
including 80% by mass or more of 1,l-difluoroethane and the like as
first component(s) and 20% by mass or less of carbon dioxide as a
5 second component, the ODP is 0, but the G W is not sufficiently low.
[0014] The present invention has been made under such circumstances,
and an object thereof is to provide a working fluid composition for a
refrigerating machine that has little adverse influences on the
environment and that can achieve compatibility, thermal/chemical
10 stability and lubricity in a highly effective system at high levels.
Solution to Problem
[0015] The present inventors have made intensive studies in order to
achieve the above object, and as a result, have found that the above
problems can be solved by using a refrigerant comprising
15 monofluoroethane (WC-161), and a refrigerating machine oil with a
specific ester or ether as a base oil, leading to the completion of the
present invention.
[0016] That is, the present invention provides a working fluid
composition for a refiigerating machine, comprising: a rei7igerant
20 comprising monofluoroethane @FC- 161); and
a refiigerating machine oil comprising at least one selected from
a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as
a base oil, wherein a carbonfoxygen molar ratio of the base oil is 2.5 or
more and 5.8 or less.
25 [0017] The rekigerant may also further comprise at least one selected
from a compound represented by the following formula (A) and carbon
dioxide.
c,H4Fr (A) 1.
/ I [p represents an integer of 1 to 4, q represents an integer of 1 to 10, and
i.
r represents an integer of 0 to 5.1
5 [0018] Furthermore, in the case where the refrigerant comprises the
compound represented by the formula (A), at least one selected fkom I difluoromethane; 1,1 -difluoroethane, 1, I, 1 -trifluoroethane,
1,1,1,2-tetrafluoroethane, pentafluoroethane, 1,3,3,3-tetrafluoropropene,
2,3,3,3-tetrafluoropropene, propane (R290) and isobutane (~600i)is 1 10 preferable as the compound.
[0019] In addition, it is preferable that a mass ratio of the refrigerant to
therefrigerating machine oil be 90 : 10 to 30 : 70.
[0020] In addition, it is preferable that a global warming potential of the i !
refrigerant be 300 or less.
15 [0021] In the case where the base oil comprises a polyol ester whose i
I
carbodoxygen molar ratio is 2.5 or more and 5.8 or less, preferable !
examples of the polyol ester include polyol esters obtainable by
synthesis fiom fatty acids having 4 to 9 carbon atoms and polyhydric
alcohols having 4 to 12 carbon atoms. i
j
20 [0022] In the case where the base oil comprises a polyalkylene glycol
having a carbodoxygen molar ratio of 2.5 or more and 5.8 or less,
preferable examples of the polyakylene glycol compound include a
i compound having a homopolymerization chain of propylene oxide or a
copolymerization chain of propylene oxide and ethylene oxide, at least
25 one of both ends of the chain being blocked by an ether bond.
[0023] In the case where the base oil comprises a polyvinyl ether
having a carbonloxygen molar ratio of 2.5 or more and 5.8 or less,
preferable examples of the polyvinyl ether include a polyvinyl ether
having a structural unit represented by the following formula (1).
[Chemical Formula I]
5
0(R40),R5
@, R2 and R~ may be the same or different and each represent a
hydrogen atom or a hydrocarbon group having1 to 8 carbon atoms, R~
represents a divalent hydrocarbon group having 1 to 10 carbon atoms or
ati ether bond oxygen-containing divalent hydrocarbon group having 2
10 to 20 carbon atoms, R~ represents a hydrocarbon group having 1 to 20
carbon atoms, m represents a number such that an average value of m in
the polyvinyl ether is 0 to 10, R' to R5 may be the same or different in
each occurrence of the structural units, and when m represents 2 or i
more in one shuctural unit, a plurality of R40 may be the same or !.
15 different.]
Advantageous Effects of Invention
[0024] According to the present invention, a working fluid composition
for a refrigerating machine that has little adverse influences on the
environment and that can achieve compatibility, thermal/chemical
20 stability and lubricity in a highly effective system at high levels is
provided.
Description of Embodiments
[0025] Hereinafter, a suitable embodiment of the present invention is
described in detail.
[0026] A working fluid composition for a refi-igerating machine
according to the present embodiment comprises
a refrigerant comprising monofluoroethane, and
a refrigerating machine oil comprising at least one selected from
a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as
a base oil, wherein a carbodoxygen molar ratio of the base oil is 2.5 or
more and 5.8 or less.
[0027] In the working fluid composition for a refi-igerating machine
10 according to the present embodiment, the proportions of the refrigerant
and the refkigerathg machine oil blended are not particularly limited,
but the mass ratio of the refrigerant to the refrigerating machine oil is
preferably 90 : 10 to 30 : 70 andmore preferably 80 : 20 to 40 : 60. 1
[0028] Then, the components contained in the working fluid
15 composition for a refcigerating machine are described in detail. I
[0029] vefrigerant]
The refrigerant in the present embodiment contains
monofluoroethane @FC-161). Monofluoroethanes have one fluorine
atom in their molecules and exhibit characteristic properties.
20 [0030] That is, first, in the field in which HCFC-22 has been used as the
refrigerant, propane w 9 0 ) is most suitable as a low-GWP refrigerant
! i because of thermodynamics characteristics. Propane, however, is
highly flammable, and thus has the large problem of safety and the
following psoblem: in the case of existing with the refiigerating
25 machine oil, it is so dissolved in the refkigerating machine oil that the
viscosity of the oil is significantly reduced, causing lubricity to be
deteriorated.
[003 11 On the contrary, monofluoroethanes has a low GWP, specifically
1;
100 or less, and a boiling point of -37°C which is close to the boiling 1;
,I
.>:I.. ~ ... . ?..~. . point of HCFC-22, -41°C. Thus, its thesmodynamics characteristics ..~..,
7..; .
5 are similar to those of HCFC-22, and it is good in thermodynamics -.
-~
characteristics as the refrigerant, compatibility with the refrigerating
machine oil, and stability, even by itself. Although being flammable,
HFC-161 has an explosion lower limit of 5.0% by volume while the
explosion lower limit of propane is 2.1% by volume, and HFC-161 has
.lo a boiling point higher than that of propane by 5"C, and a lower pressure
than propane, which hardly causes refrigerant leakage and results in
.much higher safety. The refrigerant concentration in a room rarely
reaches 5.0% by volume. In addition, since monofluoroethanes have
fluorine in theis molecules, the amount thereof dissolved in the
15 reiiigerating machine oil is much smaller than that of propane, and
therefore the amount of the refrigerant charged per
refiigerationlair-conditioning apparatus is small. Thus, it is considered
that practical realization is possible by taking corresponding safety
measures. Since the amount dissolved in tlie coexisting refitgerating
20 machine oil is small, the reduction in viscosity of the reeigerating
machine oil is also small, resulting in an advantage in lubricity; and
since no double bond is present in the molecules, stability is not
problematic.
[0032] In addition, the refrigerant in the present embodiment may also
25 firther contain at least one selected from a compound represented by
;
the following formula (A) and carbon dioxide, in addition to the /:
monofluoroethane.
c&qFr (A)
[p represents an integer of 1 to 4, q represents an integer of 1 to 10, and
r represents an integer of 0 to 5,]
5 [0033] Because of containing at least one selected hom the compound
represented by the above formula (A) and carbon dioxide, the
rehigerant in the present embodiment can allow the flammability
resulting fiom the monofluoroethane to be decreased. In addition, by
adjustment of the composition of the rehigerant, it is possible to easily
10 and certainly perform adjustment of thermodynamics characteristics of
the refigerant depending on the intended use, which is effective in
terms of the increase in efficiency of a system.
[0034] Preferable components combined with the monofluoroethane
include, with listed together with the boiling point, GWP and
15 flammability noted in parentheses, HFC-32 (-52OC, 675, low
flammable), HFC-152a (-25OC, 120, flammable), WFC-143a (-47OC,
4300, low flammable), WC-134a (-26OC, 1300, non-flammable),
. . HFC-125 (-4g°C, 3400, non-flammable), HFO-1234ze (-lg°C, 6, low
flammable), HFO-1234yf (-2g°C, 4, low flammable), propane (-42OC,
20 3, highly flammable), isobutane (-lZ°C, 3, highly flammable), and
carbon dioxide (-78OC, 1, non-flammable). These components may be
used in combination of two or more.
100351 For example, in order to enhance the safety of the refrigerant
(mixed refrigerant) in the present embodiment, a non-flammable
25 refrigerant may be blended, but a non-flammable HFC refrigerant is
generally high in GWP. Then, there is a method of blending a low
flammable refrigerant for the balance of characteristics. In particular,
since carbon dioxide is non-flammable and is the standard compound of
GWP, whose GWP is as low as 1, blending thereof is effective as long
iij as it has no influence on thermodynamics characteristics. .k.<<, !
?! 5 In 'addition, while a high-pressure refrigerant, namely, a low ;I: ;.
boiling point refkigerant is blended in order to enhance efficiency, ..~~:.
...
propae is highly flammable, and thus HFC-32, HE'C-143a, and 3:
b<
HFC-125 are candidates. k;
5
[0036] For making the GWP low, HFO-1234ze, HFO-1234yf and .* ~ ~
10 carbon dioxide, and' further propane and isobutane are preferable.
LO0371 In addition, in the case where the pressure of the mixed
refrigerant is decreased for applications to fields other than the field
where HCFC-22 has been used, the refrigerant is selected from
relatively low-pressure refrigerants such as HFC-134a, HFO-1234ze
15 and HFO-1234yf whose boiling points are higher than -30°C, in 5
1
consideration of the overall balance of characteristics.
[0038] In the case where the refiigerant in the present embodiment is a
mixed refrigerant of the monofluoroethane and the above component, . .
the proportion of the monofluoroethane contained in the mixed
20 refrigerant is preferably 50% by mass or more and more preferably 60%
by mass or more. In addition, the GWP is preferably set to 300 or less,
more preferably 200 or less, and further preferably 150 or less fkom the
viewpoint of the global environment protection. Although the mixed
refiigerant for use in the present embodiment is preferably an azeotrbpic
25 mixture, it is not particularly required to be an azeotropic mixture as
long as it has physical properties necessay as the refkigerant.
[0039] [Refrigerating machine oil] 1,~.; .:. .
The refiigerating machine oil according to the present
embodiment contains at least one selected from a polyol ester, a
polyvinyl ether and a polyalkylene glycol compound as a base oil, and
5 the carbodoxygen molar ratio of the base oil is 2.5 or more and 5.8 or
less. Carbon and oxygen .h the base oil can be quantitatively analyzed
by a common elemental analysis method. Wile a carbon analysis
includes a thermal conductivity method after conversion into carbon
dioxide by burning, and a gaschromatography method, an oxygen
10 ' , analysis is commonly a carbon reduction method in which carbon
monoxide derived by carbon is quantitatively analyzed, and a ! :
Shutze-Unterzaucher method is widely put into practical use.
[0040] In the case where the base oil is a mixed base oil including two
or more components, the carbodoxygen molar ratio of each of the 1:
15 components included in the mixed base oil is not particularly Iimited as
long as the ca~bonloxygen molar ratio of the mixed base oil is 2.5 or :
more and 5.8 or less, but it is preferable that the carbon/oxygen molar i
j
ratio of each of the polyol ester, the polyvinyl ether and the
polyalkylene glycol compound be 2.5 or more and 5.8 or less. These
20 ! preferable examples are described later. 1
[0041] [Polyol ester]
The polyol ester is an ester obtainable by synthesis kom a
polyhydric alcohol and a carboxylic acid, and the carbon/dxygen molar
ratio is preferably 2.5 or more and 5.8 or less, more preferably 3.2.or
25 more and 5.0 or less, and further preferably 4.0 or more and 5.0 or less.
As the carboxylic acid, fatty acids (aliphatic monocarboxylic acids), in
pa~ticular saturated fatty acids are preferably used, and the number of
carbon atoms thereof is preferably 4 or more and 9 or less and
particularly preferably 5 or more and 9 or less. The polyol ester may
be a partial ester in which some of hydroxyl groups in the polyhydric
5 alcohol remains as hydroxyl groups without being esterified, may be a
complete ester in which all of hydroxyl groups are esterified, or may be
a mixture of the partial ester and the complete ester; but the hydroxyl
value is preferably 10 mgKOWg or less, .hrther preferably 5 mgKWg
or less, and most preferably 3 mgKOWg or less.
10 [0042] patty acid]
(a) In the case where the proportion of difluoromethane that is
poor in compatibility with the refrigerating machine oil is high among
main components of the refrigerant, i.e., hydrofluoroethane represented
by the above formula (A), difluoromethane and
15 2,3,3,3-tetrafluoropropene, for example, in the case where the
proportion of difluoromethane in the refrigerant is 40% by mass or more,
the proportion of branched fatty acids of fatty acids forming the polyol
ester is preferably 50 to 100% by mol, particularly preferably 70 to
100% by mol, and further preferably 90 to 100% by mol.
20 COO431 Specific examples of branched fatty acids having 4 to 9 carbon
atoms include branched butanoic acids, branched pentanoic acids,
branched hexanoic acids, branched heptanoic acids, branched octanoic
acids, 'and branched nonanoic acids. More specifically, fatty acids
branched at a-position andlor P-position are preferable, isobutanoic acid,
25 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, .
2-ethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid,
3,5,5-trimethylhexanoic acid, and the like are preferable, and among
them, 2-ethylhexanoic acid and/or 3,5,5-trimethylhexanoic acid is most
preferable. Herein, fatty acids other than branched fatty acids having 4
to 9 carbon atoms may be included.
[0044] (b) In the case where the total of the content of
2,3,3,3-tetrafluoropropene among main components of the refkigerant is
higher than the total of the contents of hydrofluoroethane represented by
the above formula (A) and difluoromethane, the proportion of straight
fatty acids of fatty acids is preferably 50 to 95% by mol, particularly
preferably 60 to 90% by mol, and further preferably 70 to 85% by mol
in view of high compatibility with the refrigerating machine oil.
100451 Specific examples of straight fatty acids having 4 to 9 carbon
atoms include butanoic acid, pentanoic acid, hexanoic acid, heptanoic
acid, octanoic acid, and nonanoic acid. Among them, pentanoic acid
and/or heptanoic acid is preferable, and in particular a mixed acid
thereof is most preferable. The content of stsaight pentanoic acid is
preferably 30% by mol or more in particular in terns of compatibility,
and on the other hand, is preferably 50% by mol or less and particularly
preferably 45% by mol or less in particular in terms of hydrolytic
20 stability. The content of heptanoic acid is preferably 20% by mol or
more, particularly preferably 25% by mol or more, and fixther
preferably 30% by mol or more, in terns of lubricity. On the other
hand, the content is 50% by mol or less and preferably 45% by mol or
less in particular in terms of hydrolytic stability. As branched fatty
25 acids other than straight fatty acids, branched fatty acids having 5 to 9
carbon atoms, in pasticulas, 2-ethylhexanoic acid and/or i
3,5,5-trðylhexanoic acid is preferable. . The content of
3,5,5-trimethyhexanoic acid is preferably 5% by rnol or more and
particularly preferably 10% by mol or more in particular in terms of
. .
hydrolytic stability, and on the other hand, the content is preferably 30%
5 by mol or less and particularly preferably 25% by mol or less in
particular in terms of compatibility and lubricity.
[0046] As preferable fatty acids in the cases (b), specifically, a mixed :;
!!
I; acid of straight pentanoic acid, straight heptanoic acid and
3,5,5-trimethylhexanoic acid is preferable, and this mixed acid is more .
10 preferably one containing 30 to 50% by mol of straight pentanoic acid,
I 1;
!)1t
20 to 50% by mol of straight heptanoic acid and 5 to 30% by mol of -
:.
3,5,5-trimethylhexanoic acid.
[0047] polyhydric alcohol]
As the polyhydric alcohol fonning the polyol ester, polyhydric
. -
15 alcohols having 2 to 6 hydroxyl groups .are preferably used. The
number of carbon atoms of polyhydric alcohols is preferably 4 to 12 and
particularly preferably 5 to 10. Hindered alcohols such as neopentyl
glycol, trimethylolethane, trimethylolpropane, triiethylolbutane,
di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol and
20 di-(pentaerythitol) are preferable. Since being particularly excellent
in compatibility with the rehigerant and in hydrolytic stability,
pentaerythritol or a mixed ester of pentaerythritol and
di-(pentaerythritol) is most preferable.
[0048] [~ol~vin~lether]
25 The carbonloxygen molar ratio of the polyvinyl ether is
preferably 2.5 or more and 5.8 or less, more preferably 3.2 or inore and
:. 5.8 or less, and further preferably 4.0 or more and 5.0 or less.' If the
carbodoxygen molar ratio is. less than this range, hygroscopicity is
higher, and if the ratio is more than this range, compatibility is
deteriorated. In addition, the weight average molecular weight of the
5 polyvinyl ether is preferably 200 or more and 3000 or less and more
500 or more and 1500 or less.
[0049] The polyvinyl ether preferably used in the present embodiment
has a skuctural unit represented by the following formula (1):
[Chemical Formula 21
[R', R2 and R3 may be the same or different and each represent a
hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, R4
representsa divalent hydrocarbon group having 1 to 10 carbon atoms or
an ether bond oxygen-containing divalent hydrocarbon group having 2
15 to 20 carbon atoms, R' represents a hydrocarbon group having 1 to 20
carbon atoms, m represents a number such that an average value of m in
the polyvinyl ether is 0 to 10, R' to R5 may be the same or different in
each occurrence of the structural units, and when m represents 2 or
more in one structural unit, a plurality of R40 may be the same or
20 different.]
[0050] At least one of R', R' and. R3 in the above formula (1) is
preferably a hydrogen atom, and all thereof are particularly preferably a
hydrogen atom. m in the formula (1) is preferably 0 or more and 10 or
less, particularly preferably 0 or more and 5 or less, and further
preferably 0. R5 in the f o w a (1) represents a hydrocarbon group
having 1 to 20 carbon atoms. This hydrocarbon group includes an
alkyl group, a cycloalkyl group, a phenyl group, an aryl group, an
5 arylalkyl group, and an alkyl group, and in particular ah alkyl group
having 1 to 5 carbon atoms is preferable. 1
[0051] The polyvinyl ether according to the present embodiment may
be a homopolymer constituted. by one type of the structural unit
represented by the formula (1) or a copolymer constituted by 2 or more 1ii.i;i
c i
10 type of the structural units, but the copolymer brings about the effect of
further enhancing lubricity, insulation property, hygroscopicity, and the
l i e while satis@ing compatibility. In this case, the types of monomers
serving a s raw materials, the type of an initiator, and the rate of a
copolymer can be selected to thereby adapt the performances of an oil
15 agent to the intended levels. Accordingly, the following effect is
exerted: an oil agent can be obtained at will according to requirements 1:
!i
such as lubricity and compatibility that valy depending on the type of a I1:.
I
compressor in a refrigeration system or an air-conditioning system, the i : :
material of a lubrication portion, refrigeration ability, the type of a
20 refrigerant, and the like. The copolymer may be any of a block
copolymer and a random copolymer.
[0052] In the case where the polyvinyl ether according to the present
embodiment'is a copolymer, it is preferable that the copolymer include a
structural -unit (1-1) represented by the above formula (1) wherein R5
25 represents an alkyl group having 1 to 3 carbon atoms, and a structural
unit (1-2) represented by the above folmula (1) wherein R' represents
?<
..:
an alkyl group having 3 to 20 carbon atoms, preferably 3 to 10 carbon
1:
atoms, %@her preferably 3 to 8 carbon atoms. R~ in the shuctural unit
(1-1) is particularly prefembly an ethyl group, and R~ in the structural j unit (1-2) is particularly preferably an isobutyl group. Furthermore, in ji
. ..
I..:
5 the case where the polyvinyl ether according to the present embodiment
is the copolymer including the structural units (1-1) and (1-2), the molar
ratio of the structural unit (1-1) to the structural unit (1-2) is preferably <
5 : 95 to 95 : 5, more preferably 20 : 80 to 90 : 10, and further^
preferably 70 : 30 to 90 : 10. In the case where the molar ratio departs I I. i .
10 from the above range, there is a tendency toward insufficient
. . compatibility with the refrigerant and higher hygroscopicity.
[0053] The polyvinyl ether according to the present embodiment may
be one constituted by only the structural unit represented by the above
formula (I), but may be a copolymer further including a structural unit I !
15 represented by the following formula (2). In this case, the copolymer l~
!~
may be any of a block copolymer and a random copolymer.
[Chemical Formula 31
p6 to R' may be 'the same as or different fiom one another and each
20 represent a hydrogen atom or a hydrocarbon group having 1 to 20
carbon atoms.]
[0054] [End structure of polyvinyl ether]
The polyvinyl ether according to the present embodiment can be
FPl2-0800-00
produced by polymerization of each corresponding vinyl ether-based . .,< . .~
monomer, and copolymerization of a corresponding hydrocarbon
monomer having an olefinicdouble bond with a corresponding vinyl
ether-based monomer. As the vinyl ether-based monomer
5 corresponding to the structural unit represented by the formula (I), a
monomer represented by the following formula (3) is suitable.
[Chemical Fosmula 41
bl, R', R3, R4, R' and m represent the same meaning as in R', R2, R3,
10 R4, R5 and m in the fosmda (I), respectively.
[0055] As- the polyvinyl ether according to the present embodiment,
ethers having the following end structures are suitable.
(A) Those having a structure in which one end is represented by formula
(4) or (5)and other end is represented by formula (6) or (7).]
15 [Chemical Formula 51
[R", R2' and.R3' may be the same as or different from one another and
each represent a hydrogen atom or a hydrocarbon group having 1 to 8
carbon atoms, R4' represents a divalent hydrocarbon group having 1 to
20 10 carbon atoms or an ether bond oxygen-containing divalent
hydrocarbon group having 2 to 20 carbon atoms, R~' represents a
hydrocarbon group having 1 to 20 carbon atoms, m represents a number
such that an average value of -m in the polyvinyl ether is 0 to 10, and
when m represents 2 or more, a plurality of R4'0 may be the same or
diierent.]
[Chemical Formula 61
p6', R", Rsl and R91 may be the same as or different froin one another
and each represent a hydrogen atom or a hydrocarbon group having 1 to
20 carbon atoms.]
[Chemical Formula 71
- I I
C-CH (6)
10
I I R~~
@I2, R*a~n d R~~m ay be the same as or diierent from one another and
each represent a hydrogen atom or a hydrocarbon group having 1 to 8
carbon atoms, R4* represents a divalent hydrocarbon group having 1 to
10 carbon atoms or an ether bond oxygen-containing divalent
15 hydrocarbon group having 2 to 20 carbon atoms, represents a
hydrocarbon group having 1 to 20 carbon atoms, m represents a number
such that an average value of m in the polyvinyl ether is 0 to 10, and
when m represents 2 or more, a plurality of R4'0 may be the same or
different.]
20 [Chemical Foimula 81
~ 6 2~ 7 2
- I I
C-CH
I I ~ 8 2~ 9 2
[ R ~R~7',, R8' and Rg2m ay be the same as or diierent from one another
and each represent a hydrogen atom or a hydrocarbon group having 1 to
20 carbon atoms.] ~-
i'.
//
5 [0056] (B) Those having a structure in. which one end is represented by i
the above formula (4) or (5) and' other end is rewented by the
7. following formula (8).
[Chemical Formula 91 I -.
10 [R'~, R~~ and R~~ may be the same as or different fiom one another and
each represent a hydrogen atom or a hydrocarbon group having 1 to 8 i
jl carbon atoms.] :.~
[0057] Among such polyvinyl ether-based compounds, in particular the
following is suitable as a main component of the refrigerating machine
15 oil according to the present embodiment. i
(1) Those having a structure in which one end is represented by the
formula (5) or (6) and other end is represented by the fo~mula(7 ) or (8),
wherein in the formula (I), R', R2 and R~ are each a hydrogen atom, m
represents a number of. 0 to 4, R4 represents a divalent hydrocarbon
20 group having 2 to 4 carbon atoms, and R5 represents a hydrocarbon
group having 1 to 20 carbon atoms.
(2) Those having only the structural unit represented by the formula (I),
FP12-0800-00 i
i .. !j
having a structure in which one end is represented by the fonnula (5)
and other end is represented by the formula (7), wherein hthe formula ..;. ..
(I), R', R2 and R~ are each a hydrogen atom, m represents a number of 0 i ~
to 4, IX4 represents a divalent hydrocarbon group having 2 to 4 carbon
5 atoms, and R5 represents a hydrocarbon group having 1 to 20 carbon
atoms.
(3) Those having a structure in which one end is represented by the
formula (5) or (6) and other end is represented by the formula (7) or (8),
wherein in the formula (I), R', R2 and R3 are each a hydrogen atom, m
10 represents a number of 0 to 4, R4 represents a divalent hydrocarbon
group having 2 to 4 carbon atoms, and R5 represents a hydrocarbon
group having 1 to 20 carbon atoms.
(4) Those that are each of the (1) to (3), having a structural unit in which
R~ in the formula (1) represents a hydrocarbon group having 1 to 3
15 carbon atoms, and a structural unit in which such R5 represents a
hydrocarbon group having 3 to 20 carbon atoms.
LO0581 [production of polyvinyl ether]
The polyvinyl ether according to the present embodiment can be
produced by subjecting the above monomer to radical polymerization,
20 cation polymerization, radiation polymerization, or the like. After
completion of the polymerization reaction, a usual
separatiodpurification method is if necessary conducted, and thus the
intended polyvinyl ether-based compound having the structural unit
represented by the formula (1) is obtained.
25 [0059] As described above, it is required for the polyvinyl ether
according to the present embodiment that the carbodoxygen molar ratio
is in the predetermined range, and the carbodoxygen molar ratio of a
raw material monomer can be regulated to thereby produce a polymer
whose molar. ratio is in the above range. That is, when the rate of a
monomer whose carbodoxygen molar ratio is high is high, a polymer
whose carbonloxygen molar ratio is high is obtained, and when the rate
of a monomer whose carbon/oxygen molar ratio is low is high, a
polymer whose carbonloxygen molar ratio is low is obtained. Herein,
in the case where a vinyl ether-based monomer and a hydrocarbon
monomer having an o l e f ~dco uble bond are copolymerized, a polymer
whose carbodoxygen molar mtio is higher than the carbonloxjgen
molar ratio of the vinyl ether-based monomer is obtained, -but the
proportion thereof can be regulated by the rate and the number of
carbon atoms of the hydrocarbon monomer having an olekic double
bond to be used.
[0060] In addition, in a production step of the polyvinyl ether
represented by the above formula (I), a side reaction, may be caused and
thus an unsaturated group such as an aryl group may be formed in the
molecule. If the unsaturated group is formed in the polyvinyl ether
molecule, the following phenomenon easily occurs: the thermal stability
of the polyvinyl ether itself is deteriorated, a polymerized produce is
generated to generate sludge, or antioxidative property (oxidation
preventing property) is deteriorated to generate peroxide. In particular,
if peroxide is generated, it is decomposed to generate a compound
having a carbonyl group, and the compound having a carbonyl group
further generates sludge to easily cause blockage of a capillay.
Therefore, as the polyvinyl ether according to the present enibodiment,
those in which the degree of unsatusation due to an unsaturated group
and the like is low is preferable, and specifically, the degree of
unsaturation is preferably 0.04 meqlg or less, more preferably 0.03
meqlg or less, and most preferably 0.02 meq/g or less. In addition, the
5 value is preferably 10.0 meqkg or less, more preferably 5.0
meqkg or less, and most preferably 1.0 meqkg. Furthermore, the
carbonyl value is preferably 100 ppm by weight or less, more preferably
50 ppm by weight or less, and most preferably 20 ppm by weight or
less.
10 [0061] Herein, the degree of unsaturation, the peroxide value and the
carbonyl value in the present invention are each the value measured by
the Standard Methods for the Analysis of Fats, Oils and Related
Materials, established by the Japan Oil Chemists' Society. That is, the
degree of unsaturation in the present invention is the value (meq/g)
15 obtained by reacting a Wijs solution (IC1-acetic acid solution) with a
sample, leaving the resultant to stand in a dark area, thereafter reducing
the excess IC1 to iodine; titrating the iodine content with sodium
thiosulfate to calculate the iodme value, and converting the iodine value
to the vinyl equivalent; the peroxide value in the present invention is the
20 value (meqkg) obtained by adding potassium iodide to a sample,
titrating the free iodine generated with sodium thiosulfate, and
converting the £ree iodine to the number of milliequivalents with respect
to 1 kg of the sample; and the carbonyl value in the present invention is
the value , (ppm by . weight) obtained by allowing
25 2,4-dinitrophenylhydrazine to act on a sample to yield a colorable
quinoid ion, measuring the absorbance of the sample at 480 nm, and
convexting the absorbance to the carbonyl content based on a
.., predetermined calibration curve with cinnamaldehyde as the standard . .~
~ ~ : ,
substance. The hydroxyl value is not particularly limited, but it is .>:.. ..~.~ >.. desirable that the hydroxyl value be 10 mgKOWg, preferably 5 .:$. :. .. .
t:
5 mgKOWg and further preferably 3 mgKOHIg. ,.::
1; -,
[0062] [Polyallcylene glycol compound] -> -4.
::
A
The carbonloxygen molar ratio of the polyalkylene glycol (PAG)
compound according to the present embodiment is preferably 2.5 or . ..
.>:
more and 5.8 or less, preferably 2.5 or more and 4.0 or less, and further ~ ~.
10 preferably 2.7 or more and 3.5 or less. If the molar ratio is less than
this range, hygroscopicity is high and electrical insulation property is
deteriorated, and ifthe molar ratio is more than this range, compatibility
is deteriorated. The weight average molecular weight of the
..-
polyalkylene glycol compound is preferably 200 or more and 3000 or .::. ~> .~
15 less, and more preferably 500 or more and 1500 or less.
[0063] [Structural unit of polyalkylene glycol]
Polyalkylene glycols include those of various chemical
structures, but a basic compound thereof is polyethylene glycol,
polypropyle~e glycol, polybutylene' glycol, or the like. The unit
20 -structure thereof is oxyethylene, oxypropylene, or oxybutylene, and
polyalkylene glycols can be obtained by subjecting each monomer,
ethylene oxide, propylene oxide, or butylene oxide, as a raw material, to
ring-opening polymerization.
[0064] Examples of the polyalkylene glycol include a compound
2 5 represented by the following formula (9):
R ' ~ ~ - [ ( O R ' ~ ~ ) ~ O(R9)~ ~ ~ ] ~
[R'" represents a hydrogen atom, an alkyl 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, R"~re presents an alkylene ~.~...
:..
group having 2 to 4 carbon atoms, R'03 represents a hydrogen atom, an i-
5 alkyl group having 1 to 10 carbon atoms or an acyl group having 2 to 10 :!e :
carbon atoms, f represents an integer of 1 to 80, and g represents an
integer of 1 to 8.1 i.
i
I.
[0065] In the above formula (9), the alkyl group represented by each of i.
R'" and R''~ may be any of straight, branched and cyclic alkyl groups.
10 The number of carbon atoms of the akyl group is preferably 1. to 10 and i'
more preferably 1 to 6. If the number of carbon atoms of the alkyl !
!:
group is more than 10, compatibility with a working medium tends to be
deteriorated.
[0066] In addition, the alkyl group portion of the acyl group represented
1'
I !
15 by each of R'" and R'O~ may be any of straight, branched and cyclic !.
alkyl group portions. The number of carbon atoms of the acyl group is
preferably 2 to 10 and more preferably 2 to 6. If thenumber of carbon
atoms of the acyl group is more than 10, compatibility with a working i
medium may be deteriorated to cause phase separation.
20 [0067] In the case where both of the groups represented by R'" and
R103 q akyl groups or acyl groups, the groups represented by R'O' and
R103 may be the same or different. Furthermore, when g represents 2
or more, a plurality of R'" and R103 in the same molecule may be the
same or different.
25 COO681 In the case where the group represented by R'" is a residue of a
compound having 2 to 8 hydroxyl groups, this compound may be a
27
chain group or may be a cyclic group.
[0069] In the polyallcylene glycol represented by the above formula (9),
at least one of R"' and R'03 is preferably an alkyl group (more
preferably an allcyl group having 1 to 4 carbon atoms) and particularly
5 preferably a metliyl group in terms of compatibility with a working
medium.
[0070] Furthermore, both of R"' and R ' O ~ are preferably an allcyl group
(more preferably allcyl groups having 1 to 4 carbon atoms) and
particularly preferably a methyl group in terms of thermal/chernical
10 stability.
[0071] Preferably, any one of R"' and R'03 is an alkyl group (more
preferably an alkyl group having 1 to 4 carbon atoms) and other thereof
is a hydrogen atom, and particularly preferably, one is a methyl group
and other is a hydrogen atom, in terms of easiness of production and
15 cost. In addition, both of R"' and Rlo3 are preferably a hydrogen atom
. .
in terms of lubricity and solubility of sludge.
[0072] R'02 in the above formula (9) represents an allcylene group 6
having 2 to 4 carbon atoms, and specific examples of such an alkylene
group include an ethylene group, a propylene group, and a butylene
20 group. In addition, an oxyalkylene group as a repeating unit
i
represented by OR"^ includes an oxyethylene group, an oxypropylene i
group, and an oxybutylene group. Oxyalkylene groups in the same
molecule may be the same, and 2 or more oxyalkylene groups may be
included.
25 [0073] With respect to the polyalkylene glycol represented by the above
formula (9), a copolymer including an oxyethylene group @0) and an
compatibility with a working medium and viscosity-temperature
characteristics, and in this case, the proportion (EO/(PO+EO)) of the
oxyethylene group in the sum of the oxyethylene group and the
5 o ~ ~ ~ r o ~gr~oulpe isn peref erably in a range fiom 0.1 to 0.8 and more
preferably in a range horn 0.3 to 0.6 in terms of baking load and 1; I
viscosity-temperature characteristics.
[0074] In addition, the value of EOJ(l'DtE0) is preferably in a range
from 0 to 0.5, more preferably in a range from 0 to 0.2, and most
10 preferably 0 (namely, propylene oxide homopolymer), in terms of
hygroscopicity and thermaI and oxidation stability.
[0075] In the above formula (9), f represents the number of repetitions
of the oxyalkylene group 0 ~ ' ('d~egr ee of polymerization), and
represents an integer of 1 to 80. In addition, g represents an integer of
15 1 to 8. For example, in the case where R'" represents an alkyl group
or an acyl group, g represents 1. In the case where R''' represents a
residue of a compound having 2 to 8 hydroxyl groups, g represents the
number of hydroxyl groups in the compound.
[0076] In addition, the product (f x g) of f and g is not particularly
20 limited, but it is preferable that the average value off x g be 6 to 80 in
order to satisfy the above-described requirements and performances as
the lubricating oil for a rehigerating machine in a well-balanced
manner.
[0077] The number average molecular weight of the polyalkylene
25 glycol represented by the formula (9) is preferably 500 to 3000, M e r
preferably 600 to 2000 &d more preferably 600 to 1500, and it -is
. .
preferable. that f represent a number so that the number average
molecular weight of the polyalkylene glycol satisfies the above
conditions. In the case where the number average molecular weight of
the polyalkylene glycol is too low, lubricity under coexistence with the .
.
refrigerant is insufficient. On the other hand, in the case where the
number average molecular weight is too high, a composition range in
which compatibility with the refrigerant is exhibited' wder low
temperature conditions is narrow, and lubrication failure in a refrigerant
compressor and inhibition of heat exchange in an evaporator easily
occur.
[0078] The hydroxyl value of the polyalkylene glycol is not particularly
limited, but it is desirable that the hydroxyl value be 100 mgKOWg or
less, preferably 50 mgKOWg or less, further preferably 30 mgK0Hg
or less, and most preferably 10 mgKOWg or less.
[0079] The polyalkylene glycol according to the present embodiment
can be synthesized using a conventionally known method ("Alkylene
- Oxide Polymers", Shibata, M, et al., Kaibundo, issued onNovember 20,
1990). For example, the polyablene glycol represented by the above
formula (9) is obtained by performing addition polymerization of one or
more predetermined alkylene oxides to an alcohol (R'O'OH; R"'
represents the same meaning as in R'" in the above formula (9)), and
subjecting the hydroxyl group at the end to etherification or
esterification. Herein, in the case where two or more different alkylene
oxides are used in the production step, the resulting polyalkylene glycol
may be .any of a random copolymer and a block copolymer, but it is
preferably a block copolymer because of tending to be more excellent in
oxidation stability and lubricity, and preferably a random copolymer
because of tending to be more excellent in low-temperature fluidity.
[0080] The kinematic viscosity at 100°C of the polyalkylene glycol
according to the present embodiment is preferably 5 to 20 d s ,
preferably 6 to 18 mm2/s, more preferably 7 to 16 mm2/s, further
preferably 8 to 15 mm2/s, and most preferably 10 to 15 mm2/s. If'the
kinematic viscosity at 100°C is less than the above lower limit, lubricity
under coexistence with the refrigerant is insufficient, and on the other
hand, if the kinematic viscosity at 100°C is more than the above upper
l i t , a composition range in which compatibility with the refiigerant is
exhibited is narrow, and lubrication failure in a refrigerant compressor
and inhibition of heat exchange in an evaporator easily occur. In
addition, the kinematic viscosity at 4 0 0 ~of the poly~lkyleneg lycol is
preferably 10 to 200 rnm2/s and more preferably 20 to 150 d s . If
the kinematic viscosity at 40°C is less than 10 mm2/s, lubricity and
sealability of a compressor tend to be deteriorated, and if the kinematic
viscosity at 40°C is more than 200 m&s, a composition range in which
compatibility with the refiigerant is exhibited under low temperature
conditions tends to be narrow, and lubrication failure in a refrigerant
compressor and inhibition of heat exchange in an evaporator tend to
easily occur.
i
[0081] In addition, the pour point of the polyalkylene glycol
represented by the above formula (9) is preferably -lO°C or lower and
more preferably -20 to -50°C. If a polyalkylene glycol having a pour
point of -10°C or higher is used, the refrigerating machine oil tends to
be solidified at a low temperature in the refkigerant circulation system.
[0082] In addition, in the production step of the polyalkylene glycol of 1:
the above formula (9), alkylene oxides such, as propylene oxide may
cause a side reaction and thus an unsaturated group such as an aryl
group may be formed in the molecule. If an unsaturated group is
5 formed in the polyalkylene glycol molecule, the following phenomenon
easily occurs: the thermal stability of the polyalkylene glycol itself is
deteriorated, a polymerized produce is generated to generate sludge, or
antioxidative property (oxidation prevention property) is deteriorated to
generate peroxide. In particular, if peroxide is generated, it is
10 decomposed to generate a compound having a carbonyl group, and the
compound having a carbonyl group hrther generates sludge to easily
cause blockage of a capillruy.
[0083] Accordingly, as the polyalkylene glycol according to the present
embodiment, one in which the degree of unsaturation due to an
15 unsaturated group and the like is low is preferable, and specifically, the
degree of unsaturation is preferably 0.04 meq/g or less, more preferably
0.03 meqlg or less, and most preferably 0.02 meq/g or less. In addition,
the peroxide' value is preferably 10.0 meqkg or less, more preferably
. .
. . 5.0 meqtkg or less, and most preferably 1.0 meqkg. Furtheirnore, the
20. carbonyl value is preferably 100 ppm by weight or less, more preferably
50 pprn by weight or less, and most preferably 20 ppm by weight or
less.
LO0841 In the present embodiment, in order to obtain a polyalkylene
glycol in which the degree of unsaturation, the peroxide value and the
25 carbonyl value are low, it is preferable that the reaction temperature at
which propylene oxide is reacted be 120°C or lower (more preferably
, ..
~: ~~ 110°C or lower). In addition, if an alkali catalyst is used during the .~.
production, an inorganic adsorbent such as activated carbon, activated
white earth, bentonite, dolomite, or aluminosilicate can be used for
removing the catalyst, to thereby reduce the degree of unsaturation. In
5 addition, it is possible to prevent the increase in peroxide value or
carbonyl value also by avoiding the polyalkylene glycol being in contact
with oxygen as much as possible during its production or use, or by ~. . .
adding an antioxidant.
I : [0085] While it is required for the polyalkylene glycol compound
10 according to the present embodiment thai the carbonloxygen molar ratio
is in a range, a polymer whose molar ratio is in the above
. ..~~. . range can be produced by selecting and regulating the types and the .:.
j;
-I:
mixing ratio of the raw matesial monomers. i:
[0086] The content of -the polyol ester, the polyvinyl ether or the
15 polyalkylene glycol compound in the ref5gerating machine oil is
preferably 80% by mass or more and particularly preferably 90% by
mass or more in total based on the total amount of the reggerating I
!
machine oil in order that the refiigerating machine oil is excellent in
characteristics demanded, such as lubricity, compatibility,
20 thermal/chemical stability, and electrical insulation property. As the
base oil, a mineral oil, a hydrocarbon-based oil such as an olefin
polymer, a naphthalene compound and alkylbenzenes, and an
'oxygen-containing synthetic oil such as carbonates, ketones, polyphenyl
ethers, silicones, polysiloxanes and perfluoroethers can be used in
25 combination but the polyol ester, the polyvinyl ether and the
polyalkylene glycol compound described later,. As the
oxygen-containing synthetic oil, among them, carbonates or ketones are
preferably used.
[0087] The kinematic viscosity of the refrigerating machine oil is not
particularly limited, but the kinematic viscosity at 40°C can be
preferably set to 3 to 1000 d s , more preferably 4 to 500 mm2/s, and
most preferably 5 to 400 m d s . In addition, the kinematic viscosity at
100°C can be preferably set to 1 to 100 r n d s and more preferably 2 to
50 mm2/s.
[0088] The volume resistivity of the refrigerating machiie oil is not
particularly limited, but it can be preferably set to 1.0 x lo9 Om or
more, more preferably 1.0 x 10'' !Am or more, and most preferably 1.0
x 10" C2.m or more. In particular, in the case where the re£?igerating
machine oil is used for a closed type refkigerating machine, a high
electrical insulation property tends to be required. In the present
invention, the volume resistivity means the value at 25°C measured
according to JIS C 2101 "Electrical Insulation Oil Test Method".
[0089] The moisture content of the re6igerating machiie oil is not
particularly limited, but it can be preferably set to 200 ppm or less, more
preferably 100 ppm or less, and most preferably 50 ppm or less based
on the total amount of the refrigerating machiie oil. In particular, in
the case where the refrigerating machine oil is used for a closed type
refrigerating machine, the moisture content is demanded to be low sdm
the viewpoint of the influence on thermaVchemica1 stability and the
electrical insulation property of the rekigerating machine oil.
[0090] The acid value of the refrigerating machine oil is not particularly
limited, but it can be preferably set to 0.1 mgKOWg or less and more
preferably 0.05 mgKOWg or less in order to prevent corrosion of a
metal used for a refrigerating machine or a pipe, and to prevent
decomposition of the ester contained in the refkigerating machine oil
according to the present embodiment. In the present invention, the
acid value means the acid value measured according to JTS K2501
"Petroleum Products And Lubricating Oils-Neutralization Value Test
Method".
[0091] The ash content of the refkigerating machine oil is not
particularly limited, but it can be preferably set to 100 ppm or less and
more preferably 50 ppm or less in order to increase the
thermal/chemical stability of the refrigerating machine oil according to
the present embodiment and to suppress the occurrence of sludge or the
like. In the present invention, the ash content means the value of the
ash content measured according to JTS K2272 "Crude Oil/Petroleum
Product Ash Content and Sulfated ~ sChont ent Test Method".
[0092] The working fluid composition for a refrigerating machine
according to the present embodiment can also be used in the form of
being blended with various additives, if necessary. While the content
of the additives is shown based on the total amount of a refrigerating
20 machine oil composition, the content of these components in the fluid
composition for a refrigerating machine is preferably 5% by mass or
less and particularly preferably 2% by mass or less based on the total
amount of a refkigerating machine oil composition.
[0093] In order to further improve the wear resistance and the load
25 resistance of the working fluid composition for a reeigerating machine
according to the present embodiment, it is possible to blend at least one
phosphorus compound selected from the group consisting of phosphates,
acidic phosphates, thiophosphates, amine salts of acidic phosphates,
chlorinated phosphates, and phosphites. These phosphorus compounds
are esters of phosphoric acid or phosphorous acid and an alkanol or a
polyether type alcohol, or derivatives thereof.
[0094] In addition, the working fluid composition for a rekigerating
machine according to the present embodiment cari contain at least one
epoxy compound selected from a phenylglycidylether type epoxy
compound, an alkylglycidylether type epoxy compound, a glycidylester
type epoxy compound, an allyloxysilane compound, an alkyloxysilane
compound, an alicyclic epoxy compound, an epoxidated fatty acid
monoester and an epoxidated vegetable oil in order to h-ther improve
the thermaVchemica1 stability thereof.
[0095] In addition, the working fluid composition for -a refrigerating
machine according to the present embodiment can if necessary contain
conventionally known additives for a refkigerating machine oil in order
to further enhance the performances thereof. Examples of such
additives includes a phenol-based antioxidant such as
di-tert-butyl-p-cresol and bisphenol A, an &nine-based antioxidant such
as phenyl-a-naphthylamine and
N,N-di(2-naphthy1)-p-phenylenediamine, a wear inhibitor such as zinc
dithiophosphate, an extreme pressure agent such as chlorinated paraffins
and a sulfur compound, an oilness agent such as fatty acids, a
defoaming agent such as silicones, a .metal deactivator such as
benzotriazole, a viscosity index improver, a pour point depressant, and a
detergent dispersant. These additives may be used singly or in
wmbination of two or more.
[0096] The working fluid compositi&n for a reEigerating machine
according to the present embodiment is preferably used for a room
air-conditioner and a cold storage chamber having a closed type
reciprocating or rotating compressor, or an open-type or closed type car
air-conditioner. In addition, the working fluid composition for a
refrigerating machine and the refrigerating machine oil according to the
present embodiment are preferably used for a cooling apparatus or the
like of a dehumidifier, a water heater, a refrigerator, a refrigeration and
cooling warehouse, a vending machine, a showcase, a chemical plant, or
the like. Furthermore, the working fluid composition for a
refrigerating machine and the refrigerating machine oil according to the
present embodiment are also preferably used for one having a
centrifugal compressor.
Examples
[0097] Hereinafter, the present invention is morespecifically described
based on Examples ahd Comparative Examples, but the present
invention is not limited to the following Examples at all.
[0098] pefiigerating machine oil]
First, 0.1% by mass of di-ter.-butyl-p-cresol (DBPC) as an
antioxidant was added to each of base oils I to 4 shown below to
prepare each of re~igeratingm achine oils 1 to 4. Various properties of
refrigerating machine oils 1 to 4 are showti in Table 1.
[Base oil]
Base oil 1: ester of mixed fatty acid of 2-ethylhexanoic acid and
3,5,5-trimethylhexanoic acid (mixing ratio (molar ratio): 50150) with
pentaeryth1:ltol. Carbonloxygen molar ratio: 4.8
Base oil 2: ester of mixed fatty acid of n-pentanoic acid, n-heptanoic
acid and 3,5,5~trimethylhexanoic acid (mixing ratio (molar ratio):
40140120) with pentaerythritol. Carbon/oxygen molar ratio: 3.3
5 Base oil 3: copolymer of ethyl vinyl ether and isobutyl vinyl ether (ethyl
vinyl' ether/isobutyl vinyl ether = 7/1 (molar ratio)). Weight average
molecular weight: 910; carbodoxygen molar ratio: 4.3
Base oil 4: compound in which both ends of polypropylene glycol were
methyl-etherified. Weight average molecular weight: 11 00;
10 carbonloxygen molar ratio: 2.9
Base oil 5: compound being copolymer of polyoxyethylene glycol and
polyoxypropylene glycol, wherein one end was methyl-etherified.
Weight average molecular weight: 1700; carbonloxygen molar ratio: 2.7
[0099] [Table 11
[dl001 [Examples 1 to 11 and Comparative Examples 1 to 91
In each of Examples 1 to 11 and Comparative Examples 1 to 9,
5 - with respect to each working fluid composition for a refrigerating
machine in which each of refrigerating machine oils 1 to 4 was
combined with each refrigerant shown in Tables 2 to 4, evaluation tests
shown below were performed. As described later, the mass ratio of the
re6igerant to the rekigerating machine oil in the. working fluid
10 composition for a refrigerating machine was changed with respect to
each test.
[0101] As the refrigerant, HFC-161-itself, or a mixed refrigerant A, B or
C in which HFC-161 was blended with HFC-134a, HCFC-32,
HFO-1234yf, and carbon dioxide (R744), which were neithes highly
5 flammable nor flammable and in which the GWP was relatively low, in
consideration of the overall characteristics so that the GWP was 300 or
less was used. in each of Examples. Herein, the value defined with
respect to the GWP of HFC-161 was not released, and thus the
maximum value, 100, was used for calculation.
10 In each of Comparative Examples, any of HFC-32 and
HFO-1234yf which were major candidates as new refrigerants in terms
of GWP value, flammability, and thermodynamics characteristics was
used.
[Refrigerant]
15 HFC- 161 : monofluoroethane (GWP: about 100)
HFC-134a: 1,1,1,2-tetrafluoroethane (GWP: 1300)
HFC-32: difluoromethane (GWP: 675)
HFO-1234yf: 2,3,3,3-tetrafluoropropene (GWJ?: 4)
Mixed refrigerant A: HFC-161/HFC-l34a = 85/15 (mass ratio, GWP:
20 280)
Mixed refrigerant B: HFC-161/HFC-32/R744 = 60/20/20 (mass ratio,
GWJ?: 195)
Mixed refkigerant C: HCF~-161~~0-123=4 6~0f1 40 (mass ratio, GWP:
62)
25 [0102] Then, with respect to each of the working fluid compositions for
a refrigerating machine in ExExarhples 1 to 11 and Comparative Examples
1 to 9, evaluation tests shown below were performed. The results are
i
I shown in Tables 2 to 4. 1
[0103]' pvaluation of compatibility]
According to JIs-K-2211, "Test Method of Compatibility of
5 Refiigerating machine Oil with Refrigerant", 2 g of eachrefrigerating
machine oil was blended with 18 g of each of the above-refrigerants
including the mixed refrigerants, and whether the refrigerant and the
refrigerating machine oil were dissolved in each other at O°C or not was
observed. The results obtained are shown in Tables 2 to 4. In Tables,
10 . "Compatible" means that the refrigerant and the refrigerating machine
oil. were dissolved in each other and "Separated" means that the
refrigerant and the refrigerating machine oil were separated to two
layers,.
[0104] pvaluation of thermallchemical stability]
15 Accordjing to JIS-K-2211, 1 g of a refrigerating machine oil
(initial ASTM color L: 0.5) in which the moisture content was adjusted
to 100 ppm or less, 1 g of each of various re~igerantsd escribed above,
and a catalyst (wire of each of iron, copper and aluminum) were
enclosed into a glass tube, and then the resultant was placed in a
20 protective tube made of iron, and heated to 17S°C and kept therein for
one week. After the test, the ASTM color of the refrigerating machine
oil and the change in. color of the catalyst color were evaluated. The
ASTM color was evaluated according to ASTM Dl 56. In addition, the
cliange in color of the catalyst was evaluated by visually obsel-ving the
25 appearance for rating as no change, no gloss, or blackened. In the case
of no gloss or blackened, the mixed liquid of the refrigerating machine
oil and the rekigerant, namely, a working fluid can be said to be
deteriorated. The results obtained are shown in Tables 2 to 4.
[OiOS] [Table 21
Refrigerating machine oil
Example 1 Example 2
-~
Compatibility
Example 3
Them&
Compatible
chemical
stabity
~efrigeratiu~ Refrigerating Refrigerating
Refrigerating machine oil
machine oil 4 machime oil 1 machine oil 3 I I
ASTM color
(ASm Dl561
5 [Table 21 (continued)
Refrigerant
Compatible
Appearan* of catalyst Cu
Appearance of catalyst Fe
Appearaoce of catalyst Al
Example 4
Mixed refrigerant ( Mixed refrigerant HFC-161 I A I A I
Compatible
L0.5
No change
No change
No change
Example 5
l~om~atibility I Compatible I Compatible I Compatible I
LO.5
Example 6
I I I
M.5.
No change
No change
No change
GWP .
No change
No change
No change
n,e,au
chemical
stability
100
ASTM color
(ASTMD156)
Appearance of catalyst Cu
Appearance of catalyst Fe
Appearance of catalyst Al
280 280
L0.5
No change
No change
No change
L0.5
No change
No change
No change
L0.5
No change
No change
No change
Refrigerating .Refrigerating Refrigerating
Refrigerating machine oil
machine oil 2 machine oil 3 machiie oil 1
[0106] [Table 31
Refrigerant
I
Mixed refrigerant Mixed refrigerant Mixed refrigerant
I B / C
(Compatibility I C&npatible I Compatible I Compatible I
Example 7 Example 8
Thermal/
Example 9
chemical
stabIlitY
[Table 31 (continued)
ASTM color
(ASTM D156)
l ~ ~ ~ e a r aonf ccaeta lystA1 I NOc hange I No change
Comparative Colnparative
I Example 10 I Example 11 I Example l I Example2 1
Appearance of catalyst Cu
Appearance of catalyst Fe
No change
Refrigerating Refrigerating ~ e f r i ~ e r a t iRne~fr igerating
Refrigerating machine oil
machine oil4 machine oil 5 machiie oil 1 machine oil 2 I I I I I
LQ.5
No change
No change
L0.5
Rekigerant
L1.0
No change
No change
G\W
No change
No change
Thermd
chemical
stability
Mixed I Mixed
62
HFC-32
refrigerant C
Compatibility
ASTM color
(ASm D156)
Appearance of catalyst Cu
Appearance of catalyst Fe
Appearance of catalyst A1
HFC-32 I
refrigerant C
62
L1.0
No change
. No change .
No change
675
Compatible
675
Compatible Separated
L1.0
No change
No change
No change
Separated
M.5
No change
No change
No change
L0.5
No change
No change
No change
Refrigerating Refrigerating Refrigerating Rekigerating
Refrigerating machine oil
machine oil 3 machine oil 4 machine oil 1 machiine oil 2 I I I / I
[O 1071 [Table 41
l~om~atihility I Separated I Separated ( Compatible I Compatible I
Comparative
Example 3
[Table 41 (continued)
Comparative
Example 4
Comparative
Example 5
m e m d
chemical
stability
No change I No gloss I No gloss I
Comparative
Example 6
ASTM color
(ASTMD156)
Appearance of catalyst Cu
Appearance of catalyst Fe
Appearance of catalystN
M.5
No change
No change
No change
No change
machine oil
No change
I Comparative I Comparative I Comparative
No gloss No gloss
No change
I machine oil 3 I machine oil 4 - machiine oil 5
No change
Example 7
ReEgerating
Compatibility
IASTM color
Example 8
chemical l~ppearanceo f catalyst Cu
Example 9
sfability 1A ~gearancoef catalyst Pe
Separated
Refrigerating
5
Industrial Applicability
Reiiigeratiig
[0108] The present invention provides a working fluid composition for i
I
use in a refrigerating machinelair-conditioner using a refrigerant !
/ i
containing HFC-161, and the composition can be used as a working
!~ . ~ fluid in a in a high-cooling efficiency refrigeration system having a ~.
5 compressor, a condenser, a throttle device, an evaporatdr, and the like
among which the refi-igerant is circulated, in particular, in a refrigerating
machinelair-conditioner having a compressor such as a rotary-type,'
swing-be, scrolling-type, or reciprocating-type compressor, and can be
suitably used in the fields of a room air-conditioner, all-in-one air
10 conditioner, an industrial refrigerating machine, a coolerator, a car
air-conditioner, and the like.
CLAIMS
1. A working fluid composition for .a refrigerating machine,
comprising:
a refiigerant comprising monofluoroethane; and
.a reEgerating machine oil comprisingat least one selected from
a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as
a base oil, wherein a carbonfoxygen molar ratio of thebase oil is 2.5 or
more and 5.8 or less.
2. The working fluid composition for a refrigerating machime
according to claim 1, wherein the refrigerant M e r comprises at least
one selected from a compound represented by the following formula
(A) and carbon dioxide.
WI (A)
[p represents an integer of 1 to 4, q represents an integer of 1 to 10, and
r represents an integer of 0 to 5.1
3. The working fluid composition for a refiig&rating machine
according to claim 2, wherein the refiigerant comprises at least one
selected from difluoromethane, 1,l-difluoroethane,
l,l,l-trifluoroethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane,
1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, propane (R290)
and isobutane (R600a) as the compound represented by the formula (A).
4. The working fluid composition. for a refrigerating machine
according to any one of claims 1 to 3, wherein a mass ratio of the
refrigerant to the refrigerating machine oil is 90 : 10 to 30 : 70.
5. The working fluid composition for a refi-igerating machine
according to any 'one of claims 1 to 4, wherein a global warming
potential of the reeigerant is 300 or less.
6. The working fluid composition for a refligerating machine
according to any oneof claims 1 to 5, wherein the base oil comprises a 1;
polyol ester having a carbodoxygen molar ratio of 2.5 or more and 5.8
5 or less, and the polyol ester is a polyol ester obtainable by synthesis .
from a fatty acid having 4 to 9 carbon atoms and a polyhydric-alcohol
j:
having 4 to 12 carbon atoms. 1
7. The working fluid composition for a refrigerating machine
according to any one of claims 1 to 6, wherein the base oil comprises a
10 polyalkylene glycol compound having a carbon/oxygen molar ratio of iI/:
2.5 or more and 5.8 or less, and the polyalkylene glycol compound isa
b
compound having a homopolymerization chain of propylene oxide or a s
copolymerization chain of propylene oxide and ethylene oxide, at least i
one of both ends of the chain being blocked by an ether bond.
15 8. The working fluid composition for a refigerating machine
according to any one of claims 1 to 7, wherein the base oil comprises a 1
polyvinyl ether having a carbodoxygen molar ratio of 2.5 or more and
5.8 or less, and the polyvinyl ether is a polyvinyl ether having a
i
structural unit represented by the following formula (1): Ij i
20 [Chemical Formula 11 j
[R', R2 and R3 may be the same or different .and each represent a
hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, R4
represents a divalent l~ydrocarbong roup having 1 to 10 carbon atoins or
an ether bond oxygen-containing divalent llydrocarban group having 2
to 20 carbon a~ toms, R' represents a hydrocarbdn group having 1 to 20
carbon atoms, m represents a nuinbes such that an average value of in in
5 the polyvjnyl jether is 0 to 10, R' to R' lniy be the same 01 diffe~enitn
j .
each occusredce of the s~ucturalu~~iatnsd, when m represents 2 or
more in one structural unit, a plurality of R~Om ay be the same or
different.]