DESCRIPTION
Title of Invention
WORKING FLUID COMPOSITION FOR REFRIGERATING
MACHINE AND REFRIGERATING MACHINE OIL
5 Technical Field
[0001] The present invention relates to a working fluid composition for
a refiigerating machine and a refrigerating machine oil. It is noted that
the term "refrigerating machine" herein embraces a vehicle air
conditioner, a dehumidifier, a refrigerator, a refrigerated warehouse, a
10 cooling apparatus used in a vending machine, a showcase, a chemical
plant or the like, a household air conditioner, a package air conditioner,
a heat pump for hot water supply, and the like.
Background Art
[0002]In the field of refrigeration and air conditioning,
15 1,1,1,2-tetrafluoroethane (R134a) that is a hydrofluorocarbon @C)
and R410A that is a mixed refrigerant of difluoromethane (R32) and
pentafluoroethane (R125) in a mass ratio of 111 are currently widely
used as refrigerants for a refrigerator, a vehicle air conditioner, a room
air conditioner, industrial refiigerating machine, and the like.
20 [0003] Patent Literature 1 discloses, as a refrigerating machine oil for
an R32 refrigerant, an ester synthesized from trimethyiolpropane andlor
neopentyl glycol and a specific dibasic acid, and a monohydric alcohol
or a rnonocarboxylic fatty acid. Besides, Patent Literatwe 2 discloses,
for use together with a single R32 refrigerant or a mixed refrigerant
25 containing 50% by mass or more of R32, an ester-based refrigerating
machine oil containing 20 to 60% by mass of a monobasic fatty acid
having 5 or less carbon atoms, using a branched fatty acid as a fatty acid
having 8 or more carbon atoms, and having a viscosity at 40°C of 32 to
100 cst.
[0004] Furthermore, with respect to a base oil for a general industrial
5 lubricating oil, Patent Literature 3 discloses a lubricating oil base oil
consisting of a synthetic ester obtained by reacting an alcoliol
component containing 90% by mass or more of trimethylolpropane with
a carboxylic acid component that contains a monocarboxylic fatty acid
having 8 to 12 carbon atoms and adipic acid, and further contains, in a
10 total amount of 90% by mass or more, caprylic acid and/or a
monocarboxylic fatty acid having 8 to 12 carbon atoms containing 90%
by mass or more of caprylic acid in total, and adipic acid.
Citation List
Patent Literature
15 [0005] Patent Literature 1: Japanese Unexamined Patent Publication
NO. 2011-184536
Patent Literature 2: Japanese Unexamined Patent Publication No.
2002-129179
Patent Jiteratwte 3: Japanese Unexamined Patent Publication No.
20 2012-102235
Summary of Invention
Technical Problem
[0006] There is a,trend, however, that a load condition in a sliding
portion of a refrigerating apparatus becomes more severe in the future,
25 and therefore, it is significant to attain both antiwear property and
stability in a case where a prescribed refrigerant coexists and is
dissolved in a refrigerating machine oil.
[0007] The present invention has been accomplished in consideration of
the above-described problem, and an object is to provide a working
fluid composition for a refrigerating machine and a refrigerating
5 machine oil that can retain a thick oil film, have a good antiwear effect,
and are excellent in stability even under a severe lubrication condition
caused when a refiigesant coexists and is dissolved in the refrigerating
machine oil.
Solution to Problem
10 [0008] The present inventors have found that a working fluid
containing a refrigerating machine oil using, as a base oil, an ester
containing a complex ester synthesized from a specific polyhydric
alcohol, a polybasic acid, and a monohydric alcohol or a
monocarboxylic fatty acid, and a polyol ester synthesized from a
15 specific polyhydric alcohol and a monocarboxylic fatty acid, and a
prescribed refrigerant can attain both antiwear property and stability,
and as a result, accomplished the present invention.
[0009] Specifically, the present invention provides a working fluid
composition-for a rekigerating machine according to [I] to [6] below,
20 and a refrigerating machine oil according to [7] below.
[OOlO]
[I] A working fluid composition for a refrigerating machine,
- comprising: a refrigerating machine oil comprising, as a bas* oil, a
mixed ester of (A) a complex ester synthesized from a polyhydric
25 alcohol comprising at least one selected from neopentyl glycol,
trimethylolpropane and pentaerythritol, at least one selected from
polybasic acids having 6 to 12 carbon atoms, and at least one selected
fiom monohydric alcohols having 4 to 18 catbon atoms and
monocarboxylic fatty acids having 4 to 18 carbon atoms, and 03) a
polyol ester synthesized fiom at least one polyhydric alcohol selected
5 fiom neopentyI glycol, trimethylolpropane, pentaemhritol and
dipentaerythritol, and at least one selected from n~onocarboxylicf atty
acids having 4 to 18 carbon atoms, in a mass ratio of (A) the complex
ester/@) the polyol ester of 5/95 to 9515; and a refrigerant selected from
carbon dioxide, 1,1,1,2-tetrafluoroethane, a mixture of difluoromethane
10 and pentafluoroethane, a mixture of difluoromethane, pentafluoroethane
and 1,1,1,2-tetrafluoroethane, and a mixture of pentafluoroethane,
1,1,1,2-tetrafluoroethane and l,l,l-trifluoroethane.
[0011]
[2] The working fluid composition for a refrigerating
15 machine according to [I], wherein the polyhydric alcohol constituting
(A) the complex ester W e r comprises a dihydric alcohol having 2 to
10 carbon atoms except neopentyl glycol.
[3] The working fluid composition for a refrigerating
machine according to [I] or [2], wherein the polyhydric alcohol
20 constituting (A) the complex ester comprises at least one selected from
neopentyl glycol and trimethylolpropane.
,[4] The working fluid composition for a refrigerating
machine according to any one of [I] to [3], wherein the polybasic acid
constituting (A) the coxnplex ester is at least one selected from adipic
25 acid and sebacic acid.
(51 The working fluid composition for a refrigerating
machine according to any one of [I] to [4], wherein the monohydric
alcohol constituting (A) the complex ester is a monohydric alcohol
having 8 to 10 carbon atoms.
[6] The working fluid composition for a refrigerating
machine according to any one of [I] to [5], wherein (El) the polyol ester
is an ester synthesized from at least one selected from neopentyl glycol
and pentae~ythritola, nd at least one selected from monocarboxylic fatty
acids having 4 to 9 carbon atoms.
[7] The working fluid composition for a refrigerating
machine according to any one of [I] to [6], wherein (B) the polyol ester
is an ester synthesized from pentaewhritol, and a mixed fatty acid of a
branched fatty acid having 4 carbon atoms and 3,5,5-trimethylhexanoic
acid.
[0012]
[8] A refrigerating machine oil, comprising, as a base oil, a
mixed ester of (A) a complex ester synthesized from a polyhydric
alcohol comprising at least one selected from neopentyl glycol,
trimethylolpropane and pentaerythritol, at least one selected from
polybasic acids having 6 to 12 carbon atoms, and at least one selected
from monohydric alcohols having 4 to 18 carbon atoms and
monocarboxylic fatty acids having 4 to 18 carbon atoms, and (B) a
polyol ester synthesized from at least one polyhydric alcohol selected
&om neopentyl glycol, trimethylolpropane, pentaewhritol and
dipentaerythritol, and at least one selected from monocarboxylic fatty
acids having 4 to 18 carbon atoms, in a mass ratio of (A) the complex
ester/@) the polyol ester of 5/95 to 9515, wherein the refrigerating
machine oil is used with a refrigerant selected from carbon dioxide,
1,1,1,2-tetrafluoroethane, a mixture of difluoromethane and
pentafluoroethane, a mixture of difluoromethane, pentafluoroethane and
1,1,1,2-tetrafluoroethane, and a mixture of pentafluoroethane,
5 1,1,1,2-tetrafluoroethane and l,l,l-trifluoroethane.
Advantageous Effects of Invention
[0013] According to the present invention, a working fluid composition
for a refrigerating machine and a refrigerating machine oil that can
retain a thick oil film, have a good antiwear efTect, and are excellent in
10 stability even under a severe lubrication condition caused when a
refrigerant coexists and is dissolved in the refrigerating machine oil can
be provided.
Description of Embodiment
[0014] Apreferred embodiment of the present invention is described in
15 detail.
[OO 151 A refrigerating machine oil according to the present embodiment
contains, as a base oil, a mixed ester of (A) a complex ester synthesized
from a polyhydric alcohol containing at least one selected from
- neopentyl glycol, himethylolpropane and pentaerythritol, at least one
20 . selected from polybasic acids having 6 to 12 carbon atoms, and at least
one selected from monohydric alcohols having 4 to 18 carbon atoms
and monocarboxylic fatty acids having 4 to 18 carbon atoms; and (B) a
x polyol aternsynthesized flom at least one polyhydric alcohol selected
from neopentyl glycol, trimethylolpropane, pentaewhritol and
25 dipentaerythritol, and at least one selected from monocarboxylic fatty
acids having 4 to 18 carbon atoms, in a mass ratio of (A) the complex
ester/(B) the polyol ester of 5/95 to 9515, and is used together with a
refrigerant selected from carbon dioxide, 1,1,1,2-tetrafluoroethane, a
mixture of difluoromethane and pentafluoroethane, a mixture of
difluoromethane, pentafluoroethane and 1,1,1,2-tetrafluoroethane, and a
5 mixture of pentafluoroethane, 1,1,1,2-tetrafluoroethane and
I, 1,l-trifluoroethane.
[0016] A working fluid composition for a refrigerating machine
according to the present embodiment contains: a refrigerating machine
oil, containing, as a base oil, a mixed ester of (A) a complex ester
10 synthesized from a polyhydric alcohol containing at least one selected
from neopentyl glycol, trimethylolpropane and pentaeiytbritol, at least
one selected from polybasic acids having 6 to 12 carbon atoms, and at
least one selected &om monohydric alcohols having 4 to 18 carbon
atoms and monocarboxylic fatty acids having 4 to 18 carbon atoms; and
15 (B) a polyol ester synthesized &om at least one polyhydric alcohol
selected from neopentyl glycol, trimethylolpropane, pentaewhritol and
dipentaerythritol, and at least one selected &om monocarboxylic fatty
acids having 4 to 18 carbon atoms, in a mass ratio of (A) the complex
ester/(B) the polyol ester of 5/95 to 9515; and a refrigerant selected from
20 carbon dioxide, 1,1,1,2-tetrafluoroethane, a mixture of difluoromethane
and pentafluoroethane, a mixture of difluorometliane, pentafluoroethane
and 1,1,1,2-tetrafluoroethane, and a mixture of pentafluoroethane,
-6 1,1,1,2-tetrafluoroethane and 1,l , l-trifluoroethane.
[0017] In one aspect, the working fluid composition for a refrigerating
25 machine of the present embodiment contains the refrigerating machine
oil of the present embodiment; and a refrigerant selected f?om carbon
dioxide, 1,1,1,2-tetrafluoroethane, a mixture of difluoromethane and
pentafluoroethane, a mixture of difluoromethane, pentafluoroethane and
1,1,1,2-tetrafluoroethane, and a mixture of pentafluoroethane,
1,1,1,2-tetrafluoroethane and l,l, 1-trifluoroethane.
5 [0018] The aforementioned complex ester has a lower compatibility
with a refrigerant because the refrigerant is difticult to dissolve therein
as compared with a conventional refrigerating machine oil, but can
retain an oil film thick. Besides, the aforementioned polyol ester is
good in the compatibility with a refrigerant. In the present
10 embodiment, since the complex ester and the polyol ester thus having
different characteristics (of, particularly, a refrigerant solubility) are
blended, the oil film can be made thick in coexistence of a refrigerant,
and accordingly, the antiwear property of the working fluid can be
improved.
15 [0019] Incidentally, a complex ester has a high molecular weight and
hence is an ester with a high viscosity. Therefore, a complex ester is
difficult to be compatible with a refrigerant and is not suitably used
singly as a base oil of a refrigerating machine oil requiring compatibility
with a refrigerant from the viewpoint of oil return to a compressor. As
20 one characteristic of the present embodiment, it is possible to make the
characteristics balanced by mixing the complex ester with an oil having
a good compatibility with a refrigerant, such as the abovedescribed
polyol ester. r
[0020] The kinematic viscosity at 40°C of the complex ester is
25 preferably 20 mm2/s or more, more preferably 40 d s or more and
further preferably 50 d s or more, and preferably 500 mm2/s or less,
more preferably 400 mm2/s or less, hrther preferably 200 mn2/s or less
and particularly preferably 90 mntn2/s or less. The kinematic viscosity
at 100°C of the complex ester is preferably 5 mm2/s or more, more
preferably 6 mm2/s or more and hrther preferably 7 mm2/s or more, and
5 preferably 30 mm2/s or less, more preferably 20 d / s or less and
further preferably 15 mm2/s or less. The viscosity index of the
complex ester is preferably 100 or more and more preferably 1 I5 or
more, and preferably 180 or less. The kinematic viscosity and the
viscosity index herein mean a kinematic viscosity and a viscosity index
10 measured in accordance with JIS K2283.
[0021] Examples of a synthesizing method for the complex ester
include:
(a) a method in wbich a molar ratio between a polyhydric alcohol and a
polybasic acid is adjusted for synthesizing an ester intermediate in
15 which some of carboxyl groups of the polybasic acid remain therein
without being esterified, and the remaining carboxyl groups are
esterified by a monohydric alcohol, and
(b) a method in which a molar ratio between a polyhydric alcohol and a
polybasic acid is adjusted for synthesizing an ester intermediate in
20 which some of hydroxyl groups of the polyhydric alcohol remain
therein without being esterified, and the remaining hydroxyl groups are
esterified by a monocarboxylic fatty acid.
A complex ester obtained by the abovedescribed method (b) is rather
inferior in the stability to a complex ester obtained by the
25 above-described method (a) because a comparatively strong acid is
produced if it is hydrolyzed when used as a refrigerating machine oil.
The complex ester of the present embodiment is preferably a complex
cster with higher stability obtained by the above-described method (a).
[0022] As the polyhydric alcohol constituting the complex ester, at least
one selected from neopentyl glycol, trimethylolpropane and
5 pentaesythritol is used. For attaining a suitable viscosity as a base oil
to attain a good low temperature characteristic, the polyhydric alcohol is
preferably neopentyl glycol or trimethylolpropane. Since the viscosity
can be widely adjusted, neopentyl glycol is more preferably used as the
polyhydric alcohol.
10 [0023] Since the lubricity can be fusther improved, the polyhydric
alcohol constituting the complex ester preferably M e r contains, in
addition to at least one selected from neopentyl glycol,
trimethylolpropane and pentaerythi-itol, a dihydric alcohol having 2 to
10 carbon atoms except neopentyl glycol. Examples of the dihydric
15 alcohol having 2 to 10 carbon atoms except neopentyl glycol include
ethylene glycol, propanediol, butanediol, pentanediol, hexanediol,
2-methyl-19-propanediol, 3-methyl-l,5-pentanediol, and
2,2-diethyl-13-pentanediol. Among these, butanediol that can attain
good characteristic balance of a resultant synthesized base oil is
20 prefei-sed. Examples of the butanediol include 1,2-butanediol,
1,3-butanediol, 1,4-butanediol and 2,3-butanediol. Among these,
1,3-butanediol and 1,4-butandiol are more prefel-sed because good
characteristics can be-thus attained. The dihydric alcohol having 2 to 10 cabon atoms except neopentyl glycol is used in an amount of
25 preferably 1.2 mol or less, more preferably 0.8 mol or less, and further
preferably 0.4 mol or less based on 1 mol of the polyhydric alcohol
selected fsom neopentyl glycol, triinethylolpropane and pentaesythsitol.
[0024] The polybasic acid constituting the complex ester is at least one
selected fsom polybasic acids having 6 to 12 carbon atoms. Examples
of such polybasic acids include adipic acid, pimelic acid, suberic acid,
5 azelaic acid, sebacic acid, phthalic acid and trimellitic acid. Among
these, from the viewpoint of good characteristic balance of a resultant
synthesized ester and easy availability, adipic acid and sebacic acid are
preferred, and adipic acid is more prefersed. This polybasic acid is
used in an amount of preferably 0.4 rnol or more, more preferably 0.5
10 mol or more, and fwther preferably 0.6 mol or more, and preferably 4
rnol or less, more preferably 3 rnol or less and fwther preferably 2.5 rnol
or less based on 1 rnol of the polyhydric alcohol selected from
neopentyl glycol, trimethylolpropane and pentaerytbitol.
[0025] If some of carboxyl soups of the polybasic acid remain, without
15 being esterifled, in the complex ester intermediate produced through the
reaction between the polyhydric alcohol and the polybasic acid, the
carboxyl groups are esterified by at least one selected from monohydric
alcohols having 4 to 18 carbon atoms. Examples of the monohydric
alcohols having 4 to 18 carbon atoms include straight or branched
20 butanol, straight or branched pentanol, straight or branched hexanol,
straight or branched heptanol, straight or branched octanol, straight or
branched nonanol, straight or branched decanol, straight or branched
dodecanol; and an aliphatic alcohol such as oleyl alcohol. From the
viewpoint of the chasacteristic balance, such monohydric alcohols
25 having 4 to 18 carbon atoms are preferably monohydric alcohols having
6 to 10 carbon atoms, and more preferably monohydric alcohols having
8 to 10 carbon atoms. Among these, 2-ethylhexanol and
3,5,5-trimethylhexanol are fisther preferred since the low temperature
characteristic of the resultant synthesized complex ester can be thus
good.
5 [0026] If some of hydroxyl groups of the polyhydric alcohol remain,
without being esterified, in the complex ester intermediate produced
through the reaction between the polyhydric alcohol and the polybasic
acid, the hydroxyl groups are esterified by at least one selected fiom
monocarboxylic fatty acids having 4 to 18 carbon atoms. Examples of
10 the monocarboxylic fatty acids having 4 to 18 carbon atoms include
straight or branched butanoic acid, straight or branched pentanoic acid,
straight or branched hexanoic acid, straight or branched heptanoic acid,
straight or branched octanoic acid, straight or branched nonanoic acid,
straight or branched decanoic acid, straight or branched dodecanoic
15 acid, and oleic acid. Such monocarboxylic fatty acids having 4 to 18
carbon atoms are preferably monocarboxylic fatty acids having 8 to 10
carbon atoms, and are more preferably 2-ethylhexanoic acid and
3,5,5-trimethylhexanoic acid from the viewpoint of the low temperature
characteristic.
20 [0027] The polyol ester of the present embodiment is a polyol ester
synthesized fkom at least one polyhydric alcohol selected from
neopentyl glycol, trimethylolpropane, pentae~ythritol and
dipentaeryphritol, and at least one selected fkom monocarbo~ylic fatty
acids having 4 to 18 carbon atoms.
25 [0028] As the polyhydric alcohol constituting the polyol ester,
trimethylolpropane and pentaerythritol are prefeired, and pentaerythsitol
is more preferred from the viewpoint of the characteristic balance.
[0029] Examples of the monocarboxylic fatty acids having 4 to 18
carbon atoms constituting the polyol ester include straight or branched
butanoic acid, straight or branched pentanoic acid, straight or branched
5 hexanoic acid, straight or branched heptanoic acid, straight or branched
octanoic acid, straight or branched nonanoic acid, straight or branched
decanoic acid, straight or branched dodecanoic acid, and oleic acid.
From the viewpoint of the low temperature characteristic, such
monocarboxylic fatty acids having 4 to 18 carbon atoms are preferably
10 monocarboxylic fatty acids having 4 to 9 carbon atoms, and more
preferably branched butanoic acid, branched pentanoic acid, branched
hexanoic acid, branched heptanoic acid, 2-ethylhexanoic acid and
3,5,5-trimethylhexanoic acid.
[0030] As the polyol ester of the present embodiment, from the
15 viewpoint of the compatibility with the refrigerant, a polyol ester of
pentaerythritol and a mixed fatty acid of two or more selected from
branched fatty acids having 4 to 9 carbon atoms is preferred, a polyol
ester of pentaemhritol and a mixed fatty acid of a branched fatty acid
having 4 carbon atoms and a branched fatty acid having 9 carbon atoms
20 is more preferred, and a polyol ester of pentaerythritol and a mixed fatty
acid of a branched fatty acid having 4 carbon atoms and
3,5,5-trimethylhexanoic acid is hrther preferred.
[003.$] The kiuematic viscosity at 40°C of the polyol eater is preferably
5 mm?s or more, more preferably 20 d s or more and further
25 preferably 30 mm2/s or more, and preferably 300 mm2/s or less, more
preferably 200 m 2 / s or less and further preferably 60 mm2/s. The
kinematic viscosity at 100°C of the polyol ester is preferably 1 mm2/s or
more, more preferably 2 mm2/s or more and further preferably 3 inm21s
or more,'and preferably 30 mm2/s or less, more preferably 15 mm2/s or
less and further preferably 7 mm2/s or more. The viscosity index of
5 the polyol ester is preferably 70 or more, more preferably 80 or more
and hrther preferably 90, and preferably 150 or less.
COO321 In the working fluid composition for a refrigerating machine, the
mass ratio between a content of (A) the complex ester and (B) a content
of the polyol ester (the content of (A)/the content of (B)) is 5/95 to 9515,
10 and is preferably 20180 to 80120, and more preferably 30170 to 70130 for
fiuther utiliing the characteristics of the respective esters.
[0033] The pour point of the refrigerating machine oil is preferably
-10°C or less, and more preferably -20°C or less. The pour point
herein means a pour point measured in accordance with JIS K2269.
15 [0034] The acid value of the refkigerating machine oil can be preferably
0.1 mgKOH/g or less, and more preferably 0.05 mgKOWg or less in
order to prevent corrosion of a metal used in a refrigerating machine or
piping and to suppress degradation of the refrigerating machine oil
itself. The acid value herein means an acid value measured in
20 accordance with JIS K2501 "determination method of acid value".
[0035] The flash point of the refrigerating machine oil is preferably
. 120°C or more, and more preferably 200°C or more. The flash point
%herein means a flash point measured in accordance with JIS K2265-4.
LO0361 The moisture content of the refrigerating machine oil is
25 preferably 200 ppm or less, more preferably 100 ppm or less, and
fbrther preferably 50 ppm or less. In particular, if it is used in a
hermetic refrigerating machine, the moisture content is required to be
small from the viewpoint of the stability and electric insulation of the
refrigerating machine oil.
[0037] The refrigerating machine oil may firl-ther contain, in addition to
5 the complex ester and the polyol ester described above, another base oil
such as a mineral base oil or a synthetic base oil. The total content of
the above-described complex ester and the above-described polyol ester
is preferably 80% by mass or more, and more preferably 95% by mass
or more based on the total amount of the refrigerating machine oil.
10 [OD381 The refrigerating machine oil can further contain various
additives for further improving the antiwear property.
[0039] Suitable examples of the additives include phosphates. Among
the phosphates, triphenyl phosphate (TPP) and tricresyl phosphate
(TCP) are prefened. Suitable examples of a sulfur additive include
15 sulfide compounds. There are a large number of sulfide compounds,
among which a monosulfide compound is preferred because the stability
of the refrigerating machine oil can be attained and quality change of
copper largely used inside a refrigerating machine can be inhibited.
[0040] The rekigerating machine oil can contain, in addition to the
20 aforementioned additives, additives conventionally used in a lubricating
oil, in a range not impairing the object of the present invention, for
further improving the performance. Examples of such additives
'i include an antioxidant, a friction modifier, an antiwear agent, an
extreme pressure agent, a rust inhibitor, a metal deactivator and an
25 antifoaming agent.
[0041J Examples of tlie antioxidant include a phenol-based compound
such as di-tert-butyl-p-cresol, and an amine-based compound such as
allcyldiphenylamine. In particular, the refkigerating machine oil
contains a phenol-based compound as an antioxidant in an amount of
preferably 0.02% by mass or more and 0.5% by mass or less based on
5 the total amount of the refrigerating machine oil.
[0042] Examples of the Ection modifier include aliphatic amines,
aliphatic amides, aliphatic imides, alcohols, esters, phosphate aminc:
salts and phosphite amine salts. An example of the anti-wear agent
includes zinc dialkyldithiophosphate. Examples of the extreme
10 pressure agent include olefin sulfide and sulfirized fats and oils.
Examples of the rust inhibitor include esters or partial esters of alkenyl
succinic acid. Examples of the metal deactivator include benzotriazole
and benzotriazole derivatives. Examples of the antifoaming agent
include silicone compounds and polyester compounds.
15 [0043] The refsigerant used together with the rekigerating machine oil
of the present embodiment and the refrigerant contained in the working
fluid composition for a refrigerating machine of the present embodiment
are selected fsom carbon dioxide, 1,1,1,2-tetrafluoroethane (R134a), a
mixture of difluoromethane (R32) and pentafluoroethane (R125), a
20 mixture of difluoromethane (R32), pentafluoroethane (R125) and
1,1,1,2-tetrafluoroethane (R134a), and a mixture of pentafluoroethane
(R125), 1,1,1,2-tetrafluoroethane (R134a) and l,l,l-trifluoroethatie
! (R143a). Such a refsigerant may bg-one, or two or more selected fsom
the above. Besides, as such a refrigerant, another refkigerant may be
25 used together in addition to the refrigerant selected from the above.
The content of the refsigerant selected fsom the above is preferably 60
to 100% by mass and more preferably 80 to 100% by mass based on the
total amount of the refrigerant.
[0044] In the mixture of difluoromethane (R32) and pentafluoroethane
(R125), a mass ratio (R32k125) can be set to, for example,
5 40-70160-30. In particular, a mixture having a mass ratio (R321R125)
of 60140, a mixture (R410A) having a mass ratio of 50150, and a
mixture (R410B) having a mass ratio of 45/55 are suitably used.
[0045] In the mixtwe of difluoromethane (R32), pentafluoroethane
(R125) and 1,1,1,2-tetrafluoroethane (R134a), a mass ratio
10 (R32R125R134a) can be set to, for example, 15-3515-40140-70, In
particular, a mixture having a mass ratio (R32R125R134a) of
30/10/60, a mixture (R407C) having a mass ratio of 23/25/52, and a
mixture (R407E) having a mass ratio of 25/15/60 are suitably used.
LO0461 In the mixture of pentafluoroethane (R125),
15 1,1,1,2-tetrafluoroethane (R134a) and l,l,l-trifluoroethane (R143a), a
mass ratio (R1251R134alR143a) can be set to, for example,
35-5511-15140-60. In particular, a mixture (R404A) having a mass
ratio (R125/R134a/R143a) of 44/4/52 is suitably used.
[0047] The content of the refrigerating machine oil in the working fluid
20 composition for a refrigerating machine is not especially limited, and is
preferably 1 part by mass or more and more preferably 2 parts by mass
or more, and preferably 500 parts by mass or less and more preferably
4 400 parts by mass or less basedon 100 parts by mass of the refrigerant. i
Examples
25 [0048] The present invention is described more specifically on the basis
of Examples and Comparative Examples, and it is noted that the present
invention is not limited to the following Examples at all.
[0049] First, base oils 1 to 8 respectively having conrpositions shown in
Tables 1 and 2 were prepared by using the following base materials.
[0050] [A] Complex Ester
5 (Al) An ester (having a kinematic viscosity at 40°C of 67.8
mm2/s, a kinetic viscosity at 100°C of 10.6 mm2/s, and a viscosity index
of 145) obtained by reacting an ester intermediate which resulted from a
reaction of neopentyl glycol (1 mol) and 1,4-butanediol (0.3 mol) with
adipic acid (2.4 mol) with 3,5,5-trimethylhexanol (2.5 rnol), and
10 distilling off a remaining unreacted substance.
(A2) An ester (having a kinematic viscosity at 40°C of 145.8
d s , a kinetic viscosity at 100°C of 17.9 mm2/s, and a viscosity index
of 136) obtained by reacting an ester intermediate which resulted kom a
reaction of neopentyl glycol (1 mol) and 1,4-butanediol(0.2 mol) with
15 adipic acid (1.9 mol) with 3,5,5-trimethylhexanol (1.1 mol) and
distilling off a remaining unseacted substance.
(A3) An ester (having a kinematic viscosity at 40°C of 67.6
mm2/s, a kinetic viscosity at 100°C of 10.6 rnm2/s, and a viscosity index
of 145) obtained by reacting an ester intermediate which resulted from a
20 reaction of neopentyl glycol (1 mol) and 1,4-butanediol (0.3 mol) with
adipic acid (2.3 mol) with 2-ethylhexanol(2.3 mol) and distilling off a
remaining unreacted substance.
(A4) An ester (having a kinematic viscosity at 40°C of 68.2 t
md/s, a kinematic viscosity at 100°C of 10.4 mm2/s, and a viscosity
25 index of 139) obtained by reacting an ester intermediate which resulted
from a reaction of neopentyl glycol (1 mol) with adipic acid (2.5 mol)
with 3,7-dimethyloctanol (2.6 mol) and distilling off a remaining
unreacted substance.
(A5) An ester (having a kinematic viscosity at 40°C of 300
mm2/s, a kinematic viscosity at 100°C of 26.2 mm2/s, and a viscosity
5 index of 115) obtained by reacting an ester intermediate which resulted
from a reaction of neopentyl glycol (1 mol) with adipic acid (0.8 mol)
with 3,5,5-trimethylhexanoic acid (0.3 mol) and distilling off a
remaining unreacted substance.
[0051] [B] Polyol Ester
10 (Bl) An ester (having a kinematic viscosity at 40°C of 69.4
mm2/s, a kinematic viscosity at 100°C of 8.2 &Is, and a viscosity
index of 82) of pentaerythritol and a mixed acid of 2-methylpropanoic
acid and 3,5,5-trimethyhexanoic acid (in amolar ratio of 35:65).
(B2) An ester (having a kinematic viscosity at 40°C of 46.2
15 mm2/s, a kinematic viscosity at 100°C of 6.3 mm2/s, and a viscosity
index of 77) of pentaerythritol and a mixed acid of 2-methylpropanoic
acid and 3,5,5-trimethylhexanoic acid (in a molar ratio of 60:40).
(l33) An ester (having a kinematic viscosity at 40°C of 68.4
mm2/s, a kinematie viscosity at 100°C of 8.4 mm2/s, and a viscosity
20 index of 91) of pentaerythritol and a mixed acid of Zethylhexanoic acid
and 3,5,5-tsimethylhexanoic acid (in a molecular ratio of 45:55).
(B4) An ester (having a kinematic viscosity at 40°C of 222.5
mm2/s, a kinematictbviscosity at 100°C of 18.8 mm2/s, and a viscosity
index of 94) of dipentaerythsitol and a mixed acid of 2-ethylhexanoic
25 acid and 3,5,5-tsimethylhexanoic acid (in a molar ratio of 50:50).
(l35) An ester (having a kinematic viscosity at 40°C of 7.5
mn2/s, a kinematic viscosity at 100°C of 2.0 mmn2/s, and a viscosity
index of 31) of neopentyl glycol and 2-ethylhexanoic acid.
(B6) An ester (having a kinematic viscosity at 40°C of 31.4
mm2/s, a kinematic viscosity at 100°C of 5.6 mm2/s, and a viscosity
5 index of 118) of pentaerythritol and a mixed acid of normal pentanoic
acid and 3,5,5-trimethylhexanoic acid (in amolar ratio of 65:35).
[0052] [Hydrocarbon Oil]
(Cl) Poly a-olefm (PAO) (having a kinematic viscosity at 40°C
of 34.0 mm2/s, a kinematic viscosity at 100°C of 6.9 mm2/s, and a
10 viscosity index of 168)
(C2) Poly a-olefin (PAO) (having a kinematic viscosity at 40°C
of 68.0 rnm2/s, a kinematic viscosity at 100°C of 9.9 mm2/s, and a
viscosity index of 128)
[0053] In these base oils, synthesis reactions of the esters of [A] and @]
15 are performed without using a catalyst and a solvent, and a slight
amount of impurities were removed by an adsorption treatment (a clay
treatment) in the final process. Incidentally, the kinematic viscosities
and the viscosity indexes were measured and calculated in accordance
with JIS K2283.
20
roo541 [Table 11
roo551 [Table 21
[0056] Next, a reftigerating machine oil was prepared by mixing
di-tert-butyl-p-cresol (DBPC) serving as an antioxidant in an amount of
0.1% by mass with each of base oils shown in Tables 3 to 17. It is
noted that base oils C1, C2 and B6 shown in Tables 3 to 17 refer to base
oils respectively consisting of the above-described base materials Cl,
Composition
(mass%)
Base
Oil6
20
-
-
-
-
-
40
40
-
-
--
A1
A2
A3
A4
A5
~1
B2
B3
B4
B5
Base
Oil7
40
-
-
-
-
-
60
-
-
Base
Oil8
-
20
-
-
-
-
-
70
10
-
Base
Oil9
-
-
40
-
-
-
-
60
-
Base
Oil10
-
-
-
40
-
-
-
-
60
-
Base
Oil11
-
-
-
-
20
-
80
-
C2 and B6.
[0057] Each of the refrigerating machine oils of Examples and
Comparative Examples was subjected to a antiwear property test and a
stability test as follows. Evaluation refrigerants used in the antiwear
5 property test and the stability test are shown in Tables 3 to 17. The
details of the respective evaluation refrigerants are as follows:
R407C: a mixture of difluoromethane/pentAuoroethane/l,l,l,2-
tetrafluoroethane (in a mass ratio of 23/25/52)
COz: carbon dioxide
10 R404A: a mixture of pentafluoroethanell, 1,l ,Ztetrafluoroethane
/l,l,l-tsifluoroethane (in a mass ratio of 44/4/52)
R134a: 1,1,1,2-tetrafluoroethane
R4 10k. a mixture of difluoromethane/pentafluoraethane (in a
mass ratio of 50150)
15 [0058] (Antiwear property Test)
A high pressure ambience friction and wear tester (employing a
rotatinglsliding method using a rotating vane member and a fixed disk
member) manufactured by Shinko Engineering Co., Ltd., which can
attain a refrigerant atmosphere similar to that in an actual compressor,
20 was used for performing the antiwear property test. As test conditions,
any of the following antiwear property tests (1) to (5) was employed in
accordance with the type of evaluation rekigerant:
5 Antiwear property test (1): R407C was used-as a reiiigerant, and
an inside pressure of a test vessel was set to 1.6 MPa.
25 Antiwear property test (2): COz was used as a reeigerant, and an
inside pressure of a test vessel was set to 1.6 MPa.
Antiwear property test (3): R404A was used as a refrigerant, and
an inside pressure of a test vessel was set to 1.6 MPa.
Antiwear property test (4): R134a was used as a refrigerant, and
an inside pressure of a test vessel was set to 1.6 MPa,
5 Antiwear property test (5): R410A was used as a refrigerant, and
an inside pressure of a test vessel was set to 3.1 MPa.
[0059] In all of the antiwear property tests (1) to (5), common
conditions of an oil amount of 600 ml, a test temperature of llO°C, a
rotation speed of 500 rpm, an applied load of 80 kgf and a test time of 1
10 hour were employed. Similarly, SKH-51 and FC250 were commonly
used respectively as the vane member and the disk member. It is noted
that the evaluation of the antiwear property was performed in
accordance with a wear depth of the vane member because the wear
amount of the disk member was extremely small. The obtained results
15 are shown in Tables 3 to 17.
[0060] (Stability Test)
The stability test was performed in accordance with JIS
K2211-09 (autoclave test) by weighing out, into an autoclave, 80g of a
sample oil having a moisture content adjusted to 100 ppm, enclosing a
20 catalyst (an iron, copper or aluminum wire having an outer diameter of
1.6 mrn and a length of 50 mm) and 20 g of the evaluation refrigerant,
and then heating the resultant to 150°C to measure the appearance and
.: the acid value (JIS C2101) of the sample oil after 150 hours. The
obtained results are shown in Tables 3 to 17.
25
[00611 [Table 31
I Evaluation Refrigerant
Example Example Example Example Example
1-1 1-2 1-3 1-4 1-5
I Bas; Oil / Baseoil
2
[0062] [Table 41 I
Antiwear
property Test
Stability Test
Evaluation Refrigerant
6.8
Wear Depth
of Vane
(w)
.I Type ofBase Oil
Appearance
Acid Value
(mdcOH/g)
War Depth
Antiwear ofvane
property Test
(wm)
6.6
Appearance
Stability Test
no
deposition
0.02
Example
1-6
6.2
Example
1-7
no
deposition
0.02
6.5
Base Oil Base Oil Base Oil
8 9 1 0
6.4
no
deposition
0.02
Example
1-8
deposition deposition deposition ,,,, 1,
no
deposition
0.02
Example
1-9
no
deposition
0.01
Example
1-10
[0063] [Table 51
100641 [Table 61
Evaluation Refrigerant 1 co2 I coz I coz 1 coz I coz I
Example
2- 1
Example
2-2
Type of Rase Oil
Stability Tat
Example
2-3
Base Oil
1
Antiwvear 8.1
property Test
Wear Depth
of Vane
Appeamnce
Acid Value
(mgKOH/g)
Example
2-4
Base Oil
2
7.9
Example
2-5
no
deposition
O.O1
Base Oil
3
7.3
no
depositiori
0.01
Base Oil
4
7.1
Base Oil
5
7.2
no
deposition
0.01
i
no
---deposition -
0.02
110
deposition
0.01
[0065] [Table 71
[0066] [Table 81
[0067] [Table 91
Evaluation Refrigerant
I Type of Base Oil
Wear Depth
property Test ofvale (w)
Stability Test
[0068] [Table 101
Example Example Example
3-1 3 -2 3 9
R404A R404A R404A
Rase Oil Base Oil Base Oil -+
deposition deposition depositior
Example
3-6
Evaluation Refrigerant I R404A
Type of Base Oil I
Wear Depth
property Test
Appem~ce
deposition
Stability Test
deposition deposition *
R404A R404A R404A R404A
Base Oil Base Oil Base Oil Base Oil
Example
3-7
deposition deposition ,,,, deposition deposition ,,I,,
Example
3-8
Example
3 -9
Example
3-10
[0069] [Table 1 l]
1 Evalnation Refriremnt I R404A I R404A I R404A I R404A I
Example
3-11
I Typo of Base Oil I I Base Oil I 1 / Base Oil C2 Base Oil I B6 1
Compuative
Example
3-1
Comparative
Example
3 -2
Antiwear
property Test
[0070] [Table 121
Comparative
Example
3-3
Stability Test
Wear Depth of
Vane (pm)
I m e of Base OiI Base Oil Base Oil Base Oil Base Oil Base Oil
/ 1 1 2 1 3 / 4 1 1 1
Appearance
Acid Value
(mgK0Wg)
Evaluation Refrigerant
9,5
110
deposition
0.01
Example
4- 1
R134a
10.3
Antiweat
property Test
Stability Test
no
deposition
0.01
Example
4-2
R134a
9.5
Wear Depth
of
9.9
Acid Value
(lugKO&)
11.3
no
deposition
0.01
Example
4-3
R134a
8.6
no
deposition
0.1
no
deposition
0,01
Example
4-4
R134a
8.5
Example
4-5
R134a
no
deposition
0.02
8.2 7.8
no
deposition
0.01
no
deposition
0.01
no
deposition
0.02
[0071] [Table 131
[0072] [Table 141
[0073] [Table 151
Evaluation Refrieerwit
Type of Base Oil
Appearance
Stability Test
Acid Value
Example
5-1
Base Oil
1
no
depositior
0.02
71 rn
deposition depositior
Example
5-2
Example
5-3
Ideposition depositi:on
Example
5-4
[0074] [Table 161
Exatnple
5-5
[0075] [Table 171
I---
Example 111-
Type of Base Oil Base Oil
Antiweat \Year Depth of
property Test Vane (pm)
11.0
Appearance deposition
Stability Test
Acid Value
Cotnpaxative
Example
5-1
Base Oil C1
no
deposition
0.01
-
Comparative
Example
5-2
Base Oil C2
no
deposition
0.01
Comparative
Exaniple
5-3
Base Oil BG /
=deposition I
Jidustrial Applicability
[0076] The working fluid composition for a refrigerating machine and
the reftigerating machine oil of the present invention are excellent in the
5 antiwear property even under severe lubrication conditions, and hence
have a remarkable effect of greatly improving the lubricity.
Accordingly, they can be suitably used in 'a refrigeratingtair
conditioning system with high cooling efficiency including a
compressor, a condenser, a throttle device, an evaporator and the like for
10 circulating a refrigerant among these, in particular, in a system including
a rotary type, swing type or scroll type compressor, and hence are useful
in the fields of room air conditioners, package air conditions,
refrigerators, vehicle air conditioners, industrial refrigerating machines
and the like.
15
CLAMS
1. A working fluid composition for a refrigerating machine,
comprising:
a refrigerating machine oil comprising, as a base oil, a mixed
5 ester of (A) a complex ester synthesized fiom a polyhydric alcohol
comprising at least one selected from neopentyl glycol,
trimethylolpropane and pentaelythritol, at least one selected from
polybasic acids having 6 to 12 carbon atoms, and at least one selected
from monohydric alcohols having 4 to 18 carbon atoms and
10 monocarboxylic fatty acids having 4 to 18 carbon atoms, and (Ei) a
polyol ester synthesized from at least one polyhydric alcohol selected
from neopentyl glycol, trimethylolpropane, pentae'ythritol and
dipentaerythritol, and at least one selected from monocarboxylic fatty
acids having 4 to 18 carbon atoms, in a mass ratio of (A) the complex
15 ester/@) the polyol ester of 5/95 to 9515; and
a refrigerant selected from carbon dioxide,
1,1,1,2-tetrafluoroethane, a mixture of difluoromethane and
pentafluoroethane, a mixture of difluoromethane, pentafluoroethane and
1,1,1,2-tetrafluoroethane, and a mixture of pentafluoroethane,
20 1,1,1,2-tetrafluoroetl~anea nd 1,1,1 -tsi£luoroethane.
2. The working fluid composition for a refrigerating machine
according to claim 1, wherein the polyhydric alcohol constituting (A)
the complex ester hther conlprises a dihydsic alcohol having 2 to 10
carbon atoms except neopentyl glycol.
25 3. The working fluid composition for a refrigerating machine
according to claim 1 or 2, wherein the polyliydric alcohol constituting
(A) the complex ester comprises at least one selected %om neopentyl
glycol and trimethylolpropane.
4. The working fluid composition for a refrigerating machine
according to any one of claims 1 to 3, wherein the polybasic acid
5 constituting (A) the complex ester is at least one selected from adipic
acid and sebacic acid.
5. The working fluid composition for a refiigerating machine
according to any one of claims 1 to 4, wherein the monohydric alcohol
constituting (A) the complex ester is a monohydric alcohol having 8 to
10 10 carbon atoms.
6. The working fluid composition for a refrigerating machine
according to any one of claims 1 to 5, wherein (B) the polyol ester is an
ester synthesized from at least one selected &om neopentyl glycol and
pentae~ythritol, and at least one selected fkom monocarboxylic fatty
15 acids having 4 to 9 carbon atoms.
7. The working fluid composition for a refrigerating machine ,
according to any one of claims 1 to 6, wherein (B) the polyol ester is an
ester synthesized from pentaerythritol, and a mixed fatty acid of a
branched fatty acid having 4 carbon atoms and 3,5,5-trimethylhexanoic
20 acid.
8. A refrigerating machine oil, comprising, as a base oil, a mixed
ester of (A) a complex ester synthesized fiom a polyhydric alcohol
comprising at least one selected from neopentyl glycol,
trimethylolpropane and pentaerythritol, at least one selected from
25 polybasic acids having 6 to 12 carbon atoms, and at least one selected
from monohydric alcohols having 4 to 18 carbon atoms and
~nollocarboxylic fatty acids having 4 to 18 carbon atoms, and (B) a
polyol ester synthesized from at least one polyhydric alcohol selected
k o n ~ neope~ttyl glycol, tri~nethylolpropatlc, pentae~ythritol and
dipentae~ythritol, and at least one selected from monocarboxylic fatty
5 acids having 4 to 18 carbon atoms, in a mass ratio of (A) the complex
ester/@) the polyol ester of 5/95 to 9515,
wherein the rekigerati~ig machine oil is used with a refrigerant
selected fiom carbon dioxide, 1,1,1,2-tetrafluoroethane, a lllixture of
dii'l~ioromethane and pentafluoroethane, a mixture of difluoromethane,
10 pentafluoroethane and 1,1,1,2-tetrafluoroethane, and a mixture of
pentafluoroethane, 1,1,1,2-tetrafluoroethane and l,l,l-trifluoroetliane.