The present invention relates to a working fluid composition for
a refi-igerating machine. It is noted that the term "refi'igerating
machine" herein embraces a vehicle air conditioner, a dehumidifier, a
refrigerator, a refrigerated warehouse, a cooling apparatus used in a
vending machine, a showcase, a chemical plant or the like, a household
10 air conditioner, a package air conditioner, a heat pump for hot water
supply, and the like.
Background Art
[0002] In the field of remgeration and air conditioning,
1,1,1,2-tetrafluoroethane (R134a) that is a hydrofluorocarbon (HFC)
15 and R410A that is a mixed refrigerant of difluoromethane (R32) and
pentafluoroethane (Rl25) in a mass ratio of 1/1 are currently widely
used as refrigerants for a refrigerator, a car air conditioner, a room air
conditioner, industrial refrigerating machine, and the like. Although
such HFC refrigerants have an ozone depletion potential (ODP) of zero,
20 they have a high global wanning potential (GWP) of 1000 or more, and
therefore, their usage is limited in accordance with what is called the
F-gas regulations aiming at the global enviromnental protection.
[0003] As an alternative for a refrigerant having a high GWP,
tetrafluoropropene is under examination as a candidate owing to its
25 the1modynamic characteristic. Since 2,3,3,3-tetrafluoropropene
(HF0-1234yf) has a GWP as low as 4, it is under examination as a
1
FP14-0021-00
potential candidate.
[0004] With respect to a base oil for a general industrial lubricating oil,
Patent Literature 1 proposes a lubricating oil base oil containing a
synthetic ester obtained by reacting an alcohol component containing
5 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 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
1 0 caprylic acid in total, and adipic acid.
Citation List
Patent Literature
[0005] Patent Literature 1: Japanese Patent Application Laid-Open No.
2012-102235
15 Summary of Invention
Technical Problem
[0006] There is a trend, however, that a load condition in a sliding
portion of a refrigerating machine becomes more severe in the future,
and therefore, there is a demand for a working fluid showing excellent
20 antiwear property in a case where a tetrafluoropropene refrigerant
coexists and is dissolved in a refrigerating machine oil.
[0007] The present invention was accomplished in consideration of the
above-described problem, and an object is to provide a working fluid
composition for a refiigerating machine that can retain a thick oil film
25 and show a high antiwcar effect and is good in long-term reliability
even under a severe lubrication condition caused when a refi·igerant
2
il
~
coexists and is dissolved in a refHgerating machine oil.
Solution to Problem
FP14-0021-00
[0008] The present inventors have discovered that a working fluid for
refrigeration/air conditioning, which comprises a refrigerating machine
5 oil using, as a base oil, an ester containing a complex ester synthesized
from specific polyhydric alcohol, polybasic acid, monohydric alcohol or
monocarboxylic fatty acid, and a polyol ester synthesized from specific
polyhydric alcohol and monocarboxylic fatty acid; and
tetrafluoropropene used as a refi·igerant, and has a high refrigerant
10 dissolved viscosity under a specific condition, forms a thick oil film to
show high antiwear property, resulting in accomplishing the present
invention.
[0009] Specifically, the present invention provides a working fluid
composition for a refrigerating machine according to the following [1]
15 to [6]:
[1] A working fluid composition for a refrigerating machine,
comprising: a refrigerating machine oil comprising, as a base oil, a
mixed ester of (A) a complex ester obtainable by synthesis of at least
one polyhydric alcohol selected fi·om neopentyl glycol,
20 trimethylolpropane and pentaerythritol, a C6-C12 polybasic acid, and a
C4-C 18 monohydric alcohol or a C4-C 18 monocarboxylic fatty acid,
and (B) a polyol ester obtainable by synthesis of from at least one
polyhydric alcohol selected from neopentyl glycol, trimethylolpropane,
pentaerythritol and dipentaerythritol, and a C4-Cl8 monocarboxylic
25 fatty acid, in a mass ratio of (A) the complex ester/(B) the polyol ester
of 5/95 to 95/5; and tetrafluoropropene as a refrigerant, wherein a
3
. ·----------------------
refi·igerant dissolved viscosity, at a temperature of 80°C and an absolute
pressure of 1.6 MPa, is 1.5 mm2/s or more.
[2] The working fluid composition for a refrigerating machine
according to [1], wherein the polyhydric alcohol constituting (A) the
5 complex ester is neopentyl glycol and/or trimethylolpropane.
[3] The working fluid composition for a refrigerating machine
according to [1] or [2], wherein the polybasic acid constituting (A) the
complex ester is adipic acid and/or sebacic acid.
[4] The working fluid composition for a refrigerating machine
10 according to any one of [1] to [3], wherein the monohydric alcohol
constituting (A) the complex ester is a C8-C10 alcohoL
[5] The working fluid composition for a refrigerating machine
according to any one of [1] to [4], wherein (B) the polyol ester is an
ester obtainable by synthesis of neopentyl glycol and/or pentaerythritol
15 and a C4-C9 monocarboxylic fatty acid.
[6] The working fluid composition for a refrigerating machine
according to any one of [1] to [5], wherein (B) the polyol ester is an
ester obtainable by synthesis of pentaerythritol and any one of a mixed
acid of a C4 monocarboxylic fatty acid and 3,5,5-trimethylhexanoic
20 acid, a mixed acid of a C5 monocarboxylic fatty acid and
3,5,5-trimethylhexanoic acid, and a mixed acid of a C4 monocarboxylic
fatty acid, a C5 monocarboxylic fatty acid and 3,5,5-trimethylhexanoic
acid.
Advantageous Effects oflnvention
25 [00 1 0] A working fluid composition for a refrigerating machine of the
present invention has, even under a severe lubrication condition in
4
FP14-0021-00
which the viscosity of a refrigerating machine oil is lowered because a
tetrafluoropropene refrigerant is dissolved therein, high antiwear
prope1ty and excellent stability, and exhibits a remarkable effect that an
apparatus can be used stably over a long period of time.
5 Description of Embodiments
[0011] A preferred embodiment of the present invention will now be
described in detail.
[0012] A working fluid composition for a refrigerating machine
according to the embodiment of the present invention comprises: a
10 refrigerating machine oil comprising, as a base oil, a mixed ester of(A)
a complex ester obtainable by synthesis of at least one polyhydric
alcohol selected from neopentyl glycol, trimethylolpropane and
pentaerythritol, a C6-C12 polybasic acid (a polybasic acid having 6 to
12 carbon atoms), and a C4-C18 monohydric alcohol (a monohydric
15 alcohol having 4 to 18 carbon atoms) or a C4-C18 monocarboxylic fatty
acid (a monocarboxylic fatty acid having 4 to 18 carbon atoms), and (B)
a polyol ester obtainable by synthesis of from at least one polyhydric
alcohol selected from neopentyl glycol, trimethylolpropane,
pentaerythritol and dipentaerythritol, and a C4-Cl8 monocarboxylic
20 fatty acid (a monocarboxylic fatty acid having 4 to 18 carbon atoms), in
a mass ratio of (A) the complex ester/(B) the polyol ester of 5/95 to
95!5; and tetrafluoropropene as a refHgerant, wherein a refrigerant
dissolved viscosity, at a temperature of 80°C and an absolute pressure of
1.6 MPa, is 1.5 mnl/s or more.
25 [0013] The aforementioned complex ester has a lower compatibility
with a refrigerant because the refi·igerant is difficult to dissolve therein
5
···-----------------------------
as compared with a conventional refrigerating machine oil, but has a
characteristic that it can retain an oil film thick. Besides, the
aforementioned polyol ester is good in the compatibility with a
refi'igerant. In the present embodiment, since the complex ester and
5 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 refiigerant, and accordingly, the antiwear property of a
resultant working fluid can be improved.
[0014] Incidentally, a complex ester is difficult to be compatible with a
10 refrigerant because it has a high molecular weight and hence is an ester
with a high viscosity, and it 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 one characteristic of
the present embodiment, it is possible to make the characteristics
15 balanced by mixing the complex ester with an oil having a good
compatibility with a refrigerant, such as the above-described polyol
ester.
[0015] A preferable kinematic viscosity of the complex ester is 20 to
500 ~Is at 40°C, a more preferable viscosity is 40 to 400 mm2/s, and
20 a further preferable viscosity is 50 to 300 mm%. Besides, the
viscosity index is preferably 100 or more, and particularly preferably
110 to 160.
[0016] Examples of a synthesizing method for the complex ester
include:
25 (a) a method in which a molar ratio between a polyhydric alcohol and a
polybasic acid is adjusted for obtaining an ester intermediate having a
6
'
FP14-0021-00
carboxyl group of the polybasic acid remammg therein, and the
carboxyl group is 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 obtaining an ester intermediate having a
5 hydroxyl group of the polyhydric alcohol remaining therein, and the
hydroxyl group is esterified by a monocarboxylic fatty acid.
A complex ester obtained by the method of (b) above is rather
inferior in stability to a complex ester obtained by the method of (a)
above because a comparatively strong acid is produced if the former is
10 hydrolyzed when used as a refrigerating machine oil. The complex
ester of the present embodiment is preferably a complex ester with
higher stability obtained by the method of (a) above.
[0017] The polyhydric alcohol constituting the complex ester is
preferably neopentyl glycol or trimethylolproparie for attaining a
15 suitable viscosity as a base oil. Incidentally, if tetravalent
pentaerythritol is used, as compared with a case of using neopentyl
glycol or trimethylolpropane, the viscosity of a resultant complex ester
tends to be higher and a low temperature characteristic also tends to be
poorer. Besides, neopentyl glycol whose viscosity can be widely
20 adjusted is more preferred.
[0018) Besides, the polyhydric alcohol constituting the complex ester
preferably further contains, in addition to at least one selected fi·om
neopentyl glycol, h·imethylolpropane and pentaerythritol, a C2-Cl0
dihydric alcohol (a dihydric alcohol having 2 to 10 carbon atoms)
25 except neopentyl glycol because thus the lubricity can be improved.
Examples of the dihydric alcohol having 2 to 10 carbon atoms except
7
------------- -- -- ---
FP14-0021-00
neopentyl glycol include ethylene glycol, propanediol, butanediol,
pentanediol, hexanediol, 2-methyl-1,3-propanediol,
3-methyl-1 ,5-pentanediol and 2,2-diethyl-1 ,3-pentanediol, and
butanediol that can attain good characteristic balance of a resultant
5 synthesized base oil is prefen·ed, and examples of the butanediol include
1,2-butanediol, 1,3-butanediol, 1,4-butanediol and 2,3-butanediol,
among which 1,3-butanediol and 1,4-butandiol are more prefe1red from
the viewpoint of characteristics. The dihydric alcohol having 2 to 10
carbon atoms except neopentyl glycol is used in an amount of
10 preferably 1.2 mol or Jess, patticularly preferably 0.8 mol or less, and
further preferably 0.4 mol or less based on 1 mol of the polyhydric
alcohol selected from neopentyl glycol, trimethylolpropane and
pentaerythritol.
[0019] The polybasic acid constituting the complex ester is a polybasic
15 acid having 6 to 12 carbon atoms. Examples of such a polybasic acid
include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,
phthalic acid and trimellitic acid, among which adipic acid and sebacic
acid that are good in the characteristic balance of a resultant synthesized
ester and in availability are preferred, and in particular, adipic acid is
20 more preferr-ed. The polybasic acid is used in an amount of preferably
0.4 to 4 mol, particularly preferably 0.5 mol to 3 mol, and fruther
preferably 0.6 mol to 2.5 mol based on 1 mol of the polyhydric alcohol
selected fi·om neopentyl glycol, trimethylolpropane and pentaerythritol.
[0020] If a carboxyl group remains in a complex ester intermediate
25 produced through the reaction between the polyhydric alcohol and the
polybasic acid, the carboxyl group is esterified by a monohydric alcohol
8
------------------------------
FP14-0021-00
having 4 to 18 carbon atoms. Examples of the monohydric alcohol
having 4 to 18 carbon atoms include straight or branched butanol,
straight or branched pentanol, straight or branched hexanol, straight or
branched heptanol, straight or branched octanol, straight or branched
5 nonanol, sh·aight or branched decanol, straight or branched dodecanol,
and an aliphatic alcohol such as oleyl alcohol. From the viewpoint of
the characteristic balance, monohydric alcohols having 6 to 10 carbon
atoms, and 8 to 10 carbon atoms in particular are prefened, among
which 2-ethylhexanol and 3,5,5-trimcthylhexanol are prefen·ed from the
10 viewpoint of a good low temperature characteristic of the synthesized
complex ester.
[0021} Alternatively, if a hydroxyl group remains in the complex ester
intermediate produced through the reaction between the polyhydric
alcohol and the polybasic acid, the hydroxyl group is esterified by a
15 monocarboxylic fatty acid having 4 to 18 carbon atoms. Examples of
the monocarboxylic fatty acid 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,
20 straight or branched decanoic acid, sh·aight or branched dodecanoic
acid, and oleic acid. Preferably, C8-C10 monocarboxylic fatty acids
(monocarboxylic fatty acid having 8 to 10 carbon atoms) are used,
among which 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid are
preferred fi·om the viewpoint of the low temperature characteristic.
25 [0022} On the other hand, the polyol ester of the present embodiment is
a polyol ester can be synthesized fi·om at least one polyhydric alcohol
9
------------------------------
FP14~0021~00
selected from neopentyl glycol, trimethylolpropane, pentaerythritol and
dipentaerythritol, and a monocarboxylic fatty acid having 4 to 18 carbon
atoms.
[0023] As the polyhydric alcohol constituting the polyol ester~
5 trimethylolpropane and pentaetythritol are preferred, and pentaerythritol
is more prefened fi·om the viewpoint ofthe characteristic balance.
[0024] Examples of the monocarboxylic fatty acid having 4 to 18
carbon atoms constituting the polyol ester include straight or branched
butanoic acid, straight or branched pentanoic acid, straight or branched
1 0 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, a
monocarboxylic fatty acid having 4 to 9 carbon atoms is preferred, and
15 branched butanoic acid, branched pentanoic acid, branched hexanoic
acid, branched heptanoic acid, 2-ethylhexanoic acid and
3,5,5-trimethylhexanoic acid are more prefetTed. Patiicularly, a
saturated monocarboxylic fatty acid having 4 or 5 carbon atoms rs
preferred.
20 [0025] From the viewpoint of the compatibility with a refrigerant, a
polyol ester obtainable by synthesis of a pentaerythritol used as the
polyhydric alcohol and a mixed acid of branched fatty acid having 4 to
9 carbon atoms used as the monocarboxylic fatty acid is the most
prefen·ed.
25 [0026] In the working fluid composition for a refrigerating machine of
the present embodiment, assuming that the content of the complex ester
10
- -------------------
FP14-0021-00
is (A) and the content of the polyol ester is (B), the ratio (A)/(B) in a
mass ratio is 5/95 to 95/5, and preferably 50/50 to 95/5 from the
viewpoint of lubricity for taking more advantages of the characteristics
of the respective esters, and preferably 50/50 to 5/95 fi:om the viewpoint
5 of the compatibility with a refi'igerant.
[0027] The kinematic viscosity at 40°C of the refrigerating machine oil
of the present embodiment is preferably 3 to 500 nm1
2/s, more
preferably 8 to 150 mm2/s, and further more preferably 20 to 100
mm%. Besides, the viscosity index of the refrigerating machine oil is
10 preferably 50 or more and patiicularly preferably 80 to 120.
(0028] The pour point of the refrigerating machine oil of the present
embodiment is preferably -10°C or less, and more preferably -20°C or
less.
[0029] The acid value of the refrigerating machine oil of the present
15 embodiment can be preferably 0.1 mgKOH!g or less, and more
preferably 0.05 mgKOHJg or less in order to prevent corrosion of a
metal used in refrigerating machine or piping and to suppress
degradation of the refi·igerating machine oil itself. It is noted that the
acid value herein means an acid value measured in accordance with ns
20 K250 1 "determination method of acid value".
[0030] The flash point of the refrigerating machine oil of the present
embodiment is preferably 120°C or more, and more preferably 200°C or
more.
[0031] The moisuture content of the refrigerating machine oil of the
25 present embodiment is preferably 200 ppm or less, more preferably 100
ppm or less, and most preferably 50 ppm or less. In patticular, if it is
11
!
FP14-0021-00
used in he1metic refrigerating machine, the moisuture content is
required to be small from the viewpoint of the stability and electric
insulation of the refr·igerating machine oil.
[0032] Besides, the refr·igerating machine oil of the present embodiment
5 may further contain, in addition to 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 complex ester and
the polyol ester is preferably 80% by mass or more, and particularly
preferably 95% by mass or more ofthe refrigerating machine oil.
10 [0033] With respect to refrigerating machine, there is a trend that
conventionally used HFC refrigerants having a high GWP are shifted to
refrigerants having a low GWP from the viewpoint of the prevention of
global wmming as described above, and therefore, refrigerating machine
oils suitable for such refrigerants are necessary, and a suitable working
15 fluid of a mixture of a refrigerant and a refr·igerating machine oil is
demanded. According to the present invention, tetrafluoropropene is
contained as a refrigerant, and the content of the tetrafluoropropene in
the refrigerant is preferably 60 to 100% by mass, and patiiculm·ly
20
preferably 80 to I 00% by mass. As the tetrafluoropropene
(HF0-1234), 2,3 ,3 ,3-tetrafluoropropene (HF0-1234yf),
I ,3,3,3-tetrafluoropropene (I-IF0-1234ze ), I,2,3,3-tetrafluoropropene
(HF0-1234ye) and the like can be used.
[0034] The mixing ratio between the refr·igerating machine oil
composition and the refrigerant in the working fluid composition for a
25 refrigerating machine of the present embodiment is not especially
limited, and the a111ount of the refr-igerating machine oil composition is
12
---------------
FP14-0021-00
preferably 1 to 500 parts by mass, and more preferably 2 to 400 parts by
mass based on 100 parts by mass of the refrigerant.
[0035] The refi·igerant-dissolved viscosity, at a temperature of 80°C and
an absolute pressure of 1.6 MPa, of the working fluid composition for a
5 refrigerating machine ofthe present embodiment is 1.5 mm2/s or more,
preferably 1.7 mm2/s or more, and usually 15.0 mm2/s or less.
[0036] The working fluid composition of the present embodiment can
further contain various additives for further improving the antiwear
property. A suitable example of the additives includes a phosphate,
10 and particularly preferable compounds are triphenyl phosphate (TPP)
and tricresyl phosphate (TCP).
[0037] Besides, suitable examples of a sulfur additive include sulfides,
and there are a large number of sulfide compounds, among which a
monosulfide compound is preferred. This is because, for example, a
15 highly active sulfur compound such as a disulfide compound degrades
the stability of a refrigerating machine oil and changes the quality of
copper often used within refrigerating machine.
[0038] The working fluid composition for a refrigerating machine of
the present embodiment can contain, in addition to the aforementioned
20 additives, additives conventionally used in a lubricating oil, such as an
antioxidant, a fi·iction modifier, an antiwear agent, an extreme pressure
agent, a rust inhibitor, a metal deactivator and an antifoaming agent, in a
range not impairing the object of the present invention, for further
improving the performance.
25 [0039] As the antioxidant, a phenol-based compound such as
di-tert-butyl-p-cresol, an amine-based compound such as
13
- ------------------- ---
FP14-0021-00
alkyldiphenylamine, or the like can be contained. In patiicular, it is
preferable to contain a phenol-based compound antioxidant in an
amount of 0.02 to 0.5% by mass based on the total amount of the
refrigerating machine oil.
5 [0040] Examples of the . friction modifier include aliphatic ammes,
aliphatic arnides, aliphatic imides, alcohols, esters, acid phosphate
amine salts and phosphite amine salts, an example of the anti-wear
agent includes zinc dialkyldithiophosphate, examples of the extreme
pressure agent include olefin sulfide and sulfurized fats and oils,
10 examples of the IUst inhibitor include alkenyl succinic esters or partial
esters, examples of the metal deactivator include benzotriazole and
benzotriazole derivatives, and examples of the antifoaming agent
include silicone compounds and polyester compounds.
Examples
15 [0041] The present invention will now be 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.
[0042] [Exatnples 1 to 8 and Comparative Examples I to 3]
In Examples I to 8 and Comparative Examples I to 3, base oils
20 having compositions shown in Tables 1 to 2 were first prepared by using
the following base materials.
[A] Complex Esters
(A-1) An ester (having a kinematic viscosity at 40°C of 67.8
mm2/s and a viscosity index of I45) obtained by reacting an ester
25 intermediate resulting fi:om a reaction of neopentyl glycol (1 mol) and
1,4-butanediol (0.3 mol) with adipic acid (2.4 mol) further with
14
--~~----
FP14-0021-00
3,5,5-trimethylhexanol (2.5 mol), and distilling off a remammg
unreacted substance.
(A-2) An ester (having a kinematic viscosity at 40°C of 77.3
mm% and a viscosity index of 148) obtained by causing an ester
5 intennediate resulting from a reaction oftrimethylolpropane (1 mol) and
1,3-butanediol (0.2 mol) with sebacic acid (2.4 mol) to futiher react
with normal heptanol (1.6 mol) and distilling off a remaining unreacted
substance.
(A-3) An ester (having a kinematic viscosity at 40°C of 68.8
10 mm2/s and a viscosity index of 120) obtained by causing an ester
intetmediate resulting from a reaction of trimethylolpropane (I mol)
with adipic acid (2.4 mol) to further react with 2-ethylhexanol (2.0 mol)
and distilling off a remaining unreacted substance.
(A-4) An ester (having a kinematic viscosity at 40°C of 71.5
15 mm2/s and a viscosity index of 114) obtained by causing an ester
intermediate resulting from a reaction of neopentyl glycol (1 mol) with
adipic acid (0.8 mol) to further react with 3,5,5-trimethylhexanoic acid
(0.5 mol) and distilling off a remaining unreacted substance.
20
[B] Polyol Esters
(B-1) An ester (having a kinematic viscosity at 40°C of 69.4
mm2/s and a viscosity index of 95) of pentaerythritol and a mixed acid
of 2-methyl propanoic acid and 3,5,5-trimethylhexanoic acid in a molar
ratio of35:65.
(B-2) An ester (having a kinematic viscosity at 40°C of 70.1
25 mm2/s and a viscosity index of 90) of pentaerythritol and a mixed acid
of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid in a molar
15
------------------
ratio of 45:55.
(B-3) An ester (having a kinematic viscosity at 40°C of 8.3
mm2/s and a viscosity index .of 56) of neopentyl glycol and
2-ethylhexanoic acid.
5 (B-4) An ester (having a kinematic viscosity at 40°C of 53.8
mm2/s and a viscosity index of 99) of pentaerythritol and a mixed acid
of pentanoic acid and 3,5,5-trimethylhexanoic acid in a molar ratio of
40:60.
[0043] In these base oils, synthesis reactions of the esters of[A] and [B]
10 are performed without using a catalyst and a solvent, and a slight
amount of impurities was removed by an adsorption treatment (a clay
treatment) in the fmal process. Incidentally, the kinematic viscosity
and the viscosity index were measured and calculated in accordance
with llS K2283.
15 [0044] Next, a refrigerating machine oil was prepared by tmxmg
di-tert-butyl-p-cresol (DBPC) serving as an antioxidant in an amount of
0.1% by mass with each of the base oils of Examples 1 to 8 and
Comparative Examples 1 to 3.
[0045] The refrigerating machine oils of Examples 1 to 8 and
20 Comparative Examples 1 to 3 were subjected to measurement of
dissolved viscosity as follows.
[0046] (Measurement of Refrigerant Dissolved Viscosity)
A 200 ml pressure resistant vessel in which a vibration type
viscometer was put was charged with 1 00 g of each of the refrigerating
25 machine oils, and after vacuum degassing the vessel, a working fluid
composition was prepared by adding an HF0-1234yf refi:igerant
16
---- ------------
FP14-0021-00
thereto, and the viscosity was measured with the pressure of the
refi·igerant and the temperature of the pressure resistant vessel adjusted
to conditions of a temperature of 80°C and an absolute pressure of 1.6
Iv!Pa. The obtained results are shown in Tables 1 to 2.
5 [004 7] [Table 1]
Example Example Example Example Example Example Example Example
I 2 3 4 5 6 7 8
Composition
of base oil
ICmass%)
A-1 50 - - - 40 20 - -
A-2 - 40 - - - - 60 -
A-3 - - 30 - - - - 60
A-4 - - - 80 - - - -
B-1 50 60 70 20 - - - -
B-2 - - - - 60 - 40 -
B-3 - - - - - - - 40
B-4 - - - - - 80 - -
Kinematic
viscosity
68.6 72.4 69.2 71.1 69.2 1.9 74.3 25.4
at 40°C
(mm2/s)
Refrigerant
dissolved 1.8 1.7 1.6 1.7 2.0 1.9 2.1 1.7 viscosity
1Cmm2/s)
17
FP14-0021-00
[0048] [Table 2]
Comparative Comparative Comparative
Example Example Example
l 2 3
Composition of base oil
(mass%) .
A-1 - - -
A-2 - - -
~ - - -
A-4 - - -
B-1 100 - -
B-2 - 100 -
B-3 - - 100
B-4 - - -
Kinematic viscosity
69.4 70.1 8.3 at 40°C (mm2/s)
Refrigerant dissolved
viscositv (mm2/s)
1.2 1.4 1.0
·-- ------------
[0049] It is understood that the working fluid compositions of
Examples 1 to 8 have high refrigerant dissolved viscosities.
[0050] Besides, each of the refrigerating machine oils of Examples 1 to
5 8 is verified to have good lubricity (antiwear property) by the following
lubricity test:
[0051] (Lubricity Test)
Test machine: high pressure ambience fi·iction and wear tester
(employing a rotating/sliding method using a rotating vane member and
10 a fixed disk member) manufactured by Shinko Engineering Co., Ltd.
15
Oil amount: 600 ml
Test temperature: ll0°C
Rotation speed: 500 rpm
Applied load: 80 kgf
Test time: I hour
Vane member: SKH-51
Disk member: FC250
18
i
'
Refrigerant: HF0-1234yf
Inside pressure of test vessel: 1.6 MPa
Industrial Applicability
FP14-0021-00
[0052] A working fluid composition for a refrigerating machine of the
5 present invention has a high viscosity when a tetrafluoropropene
refi:igerant is dissolved therein, and therefore exhibits a remarkable
effect of greatly improving lubricity. Accordingly, it can be suitably
used in a refrigeration/air conditioning system with high cooling
efficiency including a compressor, a condenser, a throttle device, an
10 evaporator and the like for circulating a refrigerant among these, in
particular, in a system including a rotary type, swing type or scroll type
compress01~ and hence is useful in the fields of room air conditioners,
package air conditions, refrigerating machines, vehicle air conditioners,
industrial refrigerating machine and the like.

CLAIMS
1. A working fluid composition for a rcfhgerating machine,
compnsmg:
a refrigerating machine oil comprising, as a base oil, a mixed
5 ester of (A) a complex ester obtainable by synthesis of at least one
polyhydric alcohol selected from neopentyl glycol, trimethylolpropane
and pentaerythritol, a C6-C12 polybasic acid, and a C4-Cl8
monohydric alcohol or a C4-Cl8 monocarboxylic fatty acid, and (B) a
polyol ester obtainable by synthesis of from at least one polyhydric
10 alcohol selected from neopentyl glycol, trimethylolpropane,
pentaerythritol and dipentaerythritol, and a C4-Cl8 monocarboxylic
fatty acid, in a mass ratio of (A) the complex ester/(B) the polyol ester
of 5/95 to 95/5; and
tetrafluoropropene as a refrigerant,
15 wherein a refrigerant dissolved viscosity, at a temperature of
80°C and an absolute pressure of 1.6 MPa, is 1.5 mm2/s or more.
2. The working fluid composition for a refrigerating machine
according to claim 1, wherein the polyhydric alcohol constituting (A)
the complex ester is neopentyl glycol and/or trimethylolpropane.
20 3. The working fluid composition for a refrigerating machine
according to claim 1 or 2, wherein the polybasic acid constituting (A)
the complex ester is adipic acid and/or sebacic acid.
4. The working fluid composition for a refi'igerating machine
according to any one of claims 1 to 3, wherein the monohydric alcohol
25 constituting (A) the complex ester is a C8-C10 alcohol.
5. The working fluid composition for a refrigerating machine
20
!
according to any one of claims 1 to 4, wherein (B) the polyol ester is an
ester obtainable by synthesis of neopentyl glycol and/or pentae1ythritol
and a C4-C9 monocarboxylic fatty acid.
6. The worldng fluid composition for a refi·igerating machine
5 according to any one of claims 1 to 5, wherein (B) tbe polyol ester is an
ester obtainable by synthesis of pentae1ythritol and any one of a mixed
acid of a C4 monocarboxylic fatty acid and 3,5,5-trimethylhexanoic
acid, a mixed acid of a CS monocarboxylic fatty acid and
3,5,5,tri.methylhexanoic acid, and a mixed acid of a C4 monocarboxylic
10 fatty acid, a CS monocarboxylic fatty acid and 3,5,5-trimethylhexanoic
acid.