DESCRIPTION
Title of Invention: REFRIGERATOR WORKING FLUID
COMPOSITION AND REFRIGERANT OIL
Technical Field
5 [0001] The present invention relates to a working fluid composition for
a refrigerating machine and a refrigerating machine oil, and more
particularly, it relates to a working fluid composition for a refrigerating
machine and a refrigerating machine oil capable of retaining a low
friction coefficient, having high wear resistance and contributing to
10 reliability improvement and power saving.
Background Art
[0002] As refrigerants for a cold storage chamber, a car air-conditioner,
a room air-conditioner, an industrial refrigerator and the like,
1,1,1,2-tetrafluoroethane (R134a) of hydrofluorocarbon (HFC), R410A
15 that is a mixed solvent of difluoroethane (R32) and pentafluoroethane
(R125) in a mass ratio of 111, and the like are conventionally widely
used.
[0003] The global warming potential (GWP) of such a HFC refrigerant
is, however, as high as 1000 or more, and therefore, the use is now
20 becoming restricted by the so-called F-gas regulation. It is
indispensable for an alternative candidate for the HFC refrigerant to
have a low GWP, and one of the candidates is a hydrocarbon refrigerant
such as isobutane (R600a) already practically used for a cold storage
chamber. Since the hydrocarbon refrigerant has an extremely low
25 GWP of 20 or less and suitable physical properties, extensive studies are
being made on it.
[0004] In the coexistence of a hydrocarbon refrigerant, since a
hydrocarbon molecule does not contain chlorine or fluorine for
increasing lubricity, lubricity improvement by the refrigerant cannot be
expected differently from a case of the HFC refrigerant or the like, and
5 in addition, since solubility of a hydrocarbon in a refrigerating machine
oil is so high that the viscosity of the oil is lowered, a lubrication
condition becomes severe, which requires a higher wear resistance of a
refrigerating machine oil than in a conventional technique. Besides,
from the viewpoint of power saving, it is required to also have a
10 performance capable of retaining a friction coefficient low.
[0005] In the field of lubricating oils widely, an oiliness agent such as
an alcohol, an ester or a long-chain fatty acid, an anti-wear agent such
as a phosphoric acid ester or a metal dithiophosphate, and an extreme
pressure agent such as an organic sulfur compound or an organic
15 halogen compound are generally known as anti-wear additives. On the
other hand, in a refrigerating machine oil, an additive cannot be used
unless it is precipitated in the coexistence of a refrigerant and harmfully
affects stability. Therefore, in a conventional refrigerating machine oil,
an alcohol-based or ester-based oiliness agent, or triphenyl phosphate or
20 tricresyl phosphate among phosphates is used.
[0006] Beside, Patent Literature 1 discloses a lubricating oil used for a
refrigerating machine containing a phosphorus-based additive and a
specific epoxy compound together, Patent Literature 2 discloses a
compressor lubricating oil, to. be used with the HFC refrigerant,
25 containing triphenyl phosphate and tri(alkylpheny1) phosphate together,
and Patent Literature 3 discloses a refrigerating machine oil, to be used
with the HFC refrigerant, containing tricresyl phosphate and glycidyl
ether epoxy or carbodiimide.
Citation List
Patent Literature
5 [0007] Patent Literature 1: Japanese Patent Application Laid-Open No.
5-171174
Patent Literature 2: Japanese Patent Application Laid-Open No.
8-157847
Patent Literature 3: Japanese Patent Application Laid-Open No.
10 9-189453
Summary of Invention
Technical Problem
[0008] According to the studies by the present inventors, however, the
refrigerating machine oils containing the aforementioned additives still
15 have room for improvement as a refrigerating machine oil for a
hydrocarbon refrigerant as follows.
[0009] First, among the above-described additives, an oiliness agent is
used for forming a lubrication film by adsorption. Therefore, if a load
condition is comparatively mild as in a mixed lubrication region, a low
20 friction coefficient can be retained; but if the load condition becomes
severe under the coexistence of a hydrocarbon refrigerant, the wear
resistance effect is lost.
[0010] On the other hand, although triphenyl phosphate or tricresyl
phosphate has the wear resistance effect, a friction coefficient becomes
25 high, since it forms a hard film on the surface of a sliding portion, and
therefore, it is not suitable for a refrigerating machine developed for
power saving. In particular, in the coexistence of a hydrocarbon
refiigerant fiiendly to the global environment, since the lubrication
condition becomes severe as described above, an additive retaining not
only high wear resistance but also a low fiiction coefficient is desired.
5 [0011] In consideration of the problems of the conventional techniques,
and an object of the present invention is to provide a working fluid
composition for a refiigerating machine and a refrigerating machine oil
that can not only attain excellent wear resistance but also retain a
sufficiently low friction coefficient even under a severe lubrication
10 condition in the coexistence of a hydrocarbon refrigerant, and are
excellent in power saving and long-term reliability.
Solution to Problem
[0012] The present inventors have found that when a specific
phosphorus compound is added to a lubricating base oil, the wear
15 resistance of a working fluid composition for a refrigerating machine
and a refrigerating machine oil can be improved and a Giction
coefficient can be retained low without harmfully affecting other
characteristics in the coexistence of a hydrocarbon reeigerant, resulting
in accomplishing the present invention.
20 [0013] Specifically, the present invention provides a working fluid
composition for a refrigerating machine comprising a refrigerating
machine oil comprising at least one lubricating base oil selected fiom a
mineral oil and a synthetic oil, and at least one phosphorus compound
selected from a mono(alkylpheny1) diphenyl phosphate having a C3-C5
25 alkyl group and a di(alkylpheny1) phenyl phosphate having two C3-C5
alkyl groups, wherein a content of the phosphorus compound is 0.01 to
5% by mass based on a total amount of the refrigerating machine oil;
and a hydrocarbon refrigerant having 2 to 4 carbon atoms.
[0014] It is preferred that the phosphorus compound is at least one
selected from a mono(butylpheny1) diphenyl phosphate having a C4
5 alkyl group and a di(butylpheny1) phenyl phosphate having two C4
alkyl groups.
[0015] It is preferred that the lubricating base oil is at least one selected
from a mineral oil, an alkylbenzene, a poly-a-olefm, an ester and an
ether, and that a kinematic viscosity at 40°C of the lubricating base oil is
10 3 to 500 mm2/s.
[0016] Furthermore, it is preferred that the lubricating base oil is at least
one or more selected from a mineral oil, an alkyl benzene, a
poly-a-olefm, a diester, a polyol ester, a complex ester, a polyalkylene
1
1 glycol, a polyalkylene glycol compound and a polyvinyl ether, and that
15 a kinematic viscosity at 40°C of the lubricating base oil is 3 to 300
mm2/s.
[0017] It is preferred that the hydrocarbon refrigerant is at least one
selected from propane (R290), propylene (R1270), normal-butane
(R600) and isobutane (R600a).
20 [0018] Besides, the present invention provides a refrigerating machine
oil comprising: at least one lubricating base oil selected from a mineral
oil and a synthetic oil; and at least one phosphorus compound selected
from a mono(alkylpheny1) diphenyl phosphate having a C3-C5 alkyl
group and a di(alkylpheny1) phenyl phosphate having two C3-C5 alkyl
25 groups, wherein a content of the phosphorus compound is 0.01 to 5% by
mass based on a total amount of the refrigerating machine oil, and the
refrigerating machine oil being used together with a hydrocarbon
refrigerant having 2 to 4 carbon atoms.
Advantageous Effects of Invention
[0019] According to the present invention, a working fluid composition
5 for a refrigerating machine and a refrigerating machine oil capable of
exhibiting remarkable effects are provided, and specifically, a working
fluid composition for a refrigerating machine and a refkigerating
machine oil which can retain an wear resistance effect as well as a low
friction coefficient even under a severe lubrication condition in the
10 coexistence of a hydrocarbon refrigerant to achieve power saving, and
can be stably used for a long period of time are provided.
Description of Embodiments
[0020] Preferred embodiments of the present invention will now be
described detail.
15 [0021] [First embodiment: Refkigerating machine oil]
A refrigerating machine oil according to frst embodiment of the
present invention contains: at least one lubricating base oil selected
from a mineral oil and a synthetic oil; and at least one phosphorus
compound selected from a mono(alkylpheny1) diphenyl phosphate
20 having a C3-C5 alkyl group and a di(alkylpheny1) phenyl phosphate
having two C3-C5 alkyl groups, and the content of the phosphorus
compound is 0.01 to 5% by mass based on the total amount of the
refrigerating machine oil. Such a refkigerating machine oil is used
together with a hydrocarbon refrigerant having 2 to 4 carbon atoms.
25 [0022] The refrigerating machine oil of the present embodiment
contains, as the lubricating base oil, at least one selected from a mineral
oil and a synthetic oil.
[0023] As the mineral oil, any of a paraffm oil, a naphthene oil and a
mixed base oil may be used. A refined lubricating oil fraction, which
is obtained by subjecting a lubricating oil fraction, resulting from
5 atmospheric pressure distillation and vacuum distillation of each of or a
mixture of two or more of these mineral oils, to an appropriate
combination of refining means for lubricating oils such as solvent
deasphalting, solvent extraction, hydrogenation refming, hydro-cracking,
solvent dewaxing, hydrogenation dewaxing, and a clay treatment, can
10 be suitably used. One of refined lubricating oil fractions having
different properties obtained fiom combinations of the respective
materials and the respective refining means can be singly used, or two
or more of them can be used in combination.
[0024] On the other $1a nd, examples of a synthetic lubricating base oil
15 include oxygen-containing compounds such as an ester and an ether,
and hydrocarbon oils such as a poly-a-olefin PAO), an
ethylene-a-olefm oligomer, an alkylbenzene and an alkyl naphthalene.
[0025] Among the oxygen-containing compounds, as the ester, ester
compounds having various molecular structures are commercially
20 available, and the ester is a base oil having peculiar viscosity
characteristic and low-temperature characteristic and characterized by a
higher flash point that1 that of a hydrocarbon base oil with the same
viscosity. The ester can be obtained by a dehydration condensation
reaction of an alcohol and a fatty acid, and in the present invention,
25 from the viewpoint of chemical stability, examples of a suitable base oil
component include a diester of a dibasic acid and a monohydric alcohol,
a polyol ester of a polyol (a neopentyl polyol in particular) and a
monocarboxylic acid, and a complex ester of a polyol, a polybasic acid
and a monohydric alcohol (or a monocarboxylic acid). Among these, a
polyol ester excellent in stability is preferred.
5 [0026] Examples of the ether include a polyalkylene glycol and a
polyvinyl ether. Examples of the polyalkylene glycol include
polypropylene glycol, polyethylene glycol, and a copolymer of
propylene oxide and ethylene oxide. With respect to an end structure,
at least one end is preferably an alkyl group, and more preferably a
10 methyl group fiom the viewpoint of the hygroscopicity. Besides, from
the viewpoint of easy producing and cost, it is preferred that one of the
ends is an alkyl group and the other is a hydrogen atom, and it is
particularly preferred that one of the ends is a methyl group and the
other is a hydrogen atom. With respqt ct to a principal skeleton, a
15 copolymer having an oxyethylene (EO) group and an oxypropylene
(PO) group is preferred from the viewpoint of the lubricity, and a ratio
of the oxyethylene group to the sum of the oxyethylene group and the
oxypropylene group (EO / PO + EO) is preferably in a range of 0.1 to
0.8, and more preferably in a range of 0.3 to 0.6. Furthermore, from
20 the vicwpoint of the hygroscopicity and thermaWchemica1 stability, a
value of EO/(PO + EO) is preferably in a range of 0 to 0.5, more
preferably in a range of 0 to 0.2, and most preferably 0 (namely, a
polymer of propylene oxide singly).
. [0027] The polyvinyl ether. has a structural unit represented by the
25 following formula (1). The polyvinyl ether of the present embodiment
may be a single polymer containing one and the same structural unit, or
a copolymer containing two or more types of structural units, and the
copolymer is preferred because the characteristics can be adjusted to be
well balanced.
[Chemical Formula 11 +[Li+ (1,
5
o(R~o),R'
[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 bivalent hydrocarbon group having 1 to
10 carbon atoms or an etheral oxygen-containing bivalent hydrocarbon
10 group having 2 to 20 carbon atoms, R~ represents a hydrocarbon group
having 1 to 20 carbon atoms, m represents a number for q1t taining an
average of m in the entire polyvinyl ether of 0 to 10, R' to R5 may be
the same in or different among each structural units, and if m is 2 or
more in one structural unit, a plurality of R40 may be the same as or
15 different from one another.]
[0028] Among the synthetic hydrocarbon oils, the poly-a-olefin (PAO)
is a copolymer of a-olefin, and hence, its characteristics can be
appropriately selected by selecting the degree of polymerization.
[0029] The alkylbenzene is divided into a linear type and a branched
20 type depending on the structure of an alkyl group, and since these types
- have different characteristics, they are used selectively depending on the
purpose.
[0030] In the present embodiment, one of the above-described mineral
oils and synthetic oils may be singly used, or two or more of them may
be used in combination.
[0031] The kinematic viscosity at 40°C of the lubricating base oil is
preferably 3 to 500 mm2/s, more preferably 3 to 300 mm2/s, and further
5 more preferably 5 to 150 d s . The viscosity index of the lubricating
base oil is preferably 10 or more. A kinematic viscosity at 40°C and a
viscosity index herein mean values measured in accordance with JIS
K2283.
[0032] The pour point of the lubricating base oil is preferably -lO°C or
10 less, and more preferably -20°C or less. A pour point herein means a
value measured in accordance with JIS K2269.
[0033] The flash point of the lubricating base oil is preferably 120°C or
more, and more preferably 200°C or more. A flash point herein means
a value measured in accordance with JIS K2265. I
15 [0034] Furthermore, the reeigerating machine oil of the present
embodiment contains at least one phosphorus compound selected from a
mono(alkylpheny1) diphenyl phosphate having a C3-C5 alkyl group and
a di(alkylpheny1) phenyl phosphate having two C3-C5 alkyl groups.
100351 The phosphorus compound of the present embodiment can be
20 represented by the following formula (2):
(R~-P~),-P(=o)-(P~),., (2)
[ R ~rep resents an alkyl group having 3 to 5 carbon atoms, Ph
represents a phenyl group, and n represents an integer of 1 or 2.1
[0036] If n is 1, the phosphorus compound represented by the above
25 formula (2) is a mono(alkylpheny1) diphenyl phosphate having a C3-C5
alkyl group. Specific examples of the mono(alkylpheny1) diphenyl
phosphate include isopropylphenyl diphenyl phosphate,
tert.-butylphenyl diphenyl phosphate and n-butylphenyl diphenyl
phosphate.
[0037] If n is 2, the phosphorus compound represented by the above
5 formula (2) is a di(alkylpheny1) phenyl phosphate having two C3-C5
alkyl groups. Examples of the di(alkylpheny1) diphenyl phosphate
include di(isopropylpheny1) phenyl phosphate, di(tert.-butylphenyl)
phenyl phosphate and di(n-butylphenyl) phenyl phosphate.
[0038] In the formula (2), R6 is preferably a butyl group from the
10 viewpoint of the lubricity of the refrigerating machine oil. Examples
of the butyl group include a normal-butyl group of the linear alkyl group,
and a tert.-butyl group of the branched alkyl group. If the number of
carbon atoms of R~ is 2 or less, the friction coefficient is so high that the
power saving is difficult to achieve. The present inventors presume
15 that it is because a film of the phosphorus compound formed in a sliding
portion becomes hard. On the other hand, if the number of carbon
atoms of R6 exceeds 5, the wear resistance effect becomes small. The
present inventors presume that it is because the affinity of the
phosphorus compound with the lubricating base oil becomes so large
20 that the concentration of the phosphorus compound in the sliding
portion is extremely lowered.
[0039] The content of the phosphorus compound is 0.01 to 5% by mass,
and preferably 0.1 to 3% by mass based on the total amount of the
refrigerating machine oil. .If the content is less than the lower limit of
25 this range, the effect to improve the lubricity cannot be exhibited. If
the content exceeds the upper limit, the influence on the stability of the
refrigerating machine oil and swelling or the like of an organic material
used in a system is unavoidably increased.
[0040] The refrigerating machine oil of the present embodiment may
contain only the lubricating base oil and the phosphoms compound, but
5 it may further contain an additive such as an antioxidant, a friction
modifier, a rust-preventive agent, a metal deactivator, or an antifoaming
agent in order to further improve the performance as long as the object
of the present invention is not impaired.
[0041] Examples of the antioxidant include a phenol compound such as
10 di-tert.-butyl-p-cresol and an amine compound such as an alkyl diphenyl
amine; examples of the friction modifier include an aliphatic amine, an
aliphatic amide, an aliphatic imide, an alcohol, an ester, an acid
phosphate amine salt and a phosphite amine salt; an example of the
rust-preventive agent includes an ester or a partial ester of alkenyl
15 succinic acid; an example of the metal deactivator includes a
benzotriazole; and examples of the antifoaming agent include a silicone
compound and an ester antifoaming agent.
[0042] The refrigerating machine oil of the present embodiment can be
preferably used as a lubricating oil for a refrigerating machine in which
20 a hydrocarbon refrigerant having 2 to 4 carbon atoms is used. Herein,
if the refrigerating machine oil of the present embodiment is applied to a
cold storage chamber in which isobutane is used as a refrigerant, it is
also necessary to have a characteristic suitable to a motorized (hermetic)
compressor, namely, a high electrical insulating property. Therefore,
25 the refrigerating machine oil of the present embodiment preferably has,
after adding an additive, a volume resistivity of lo9 i2.m or more. A
volume resistivity herein means a value measured in accordance with
JIS C2101. If an additive is used, the volume resistivity means a
volume resistivity of the refrigerating machine oil attained afier adding
the additive thereto.
5 [0043] [Second Embodiment: Working fluid composition for a
refrigerating machine]
A working fluid composition for a refrigerating machine
according to second embodiment of the present invention contains a
refrigerating machine oil that contains at least one lubricating base oil
10 selected fiom a mineral oil and a synthetic oil and at least one
phosphorus compound selected from a mono(alkylpheny1) diphenyl
phosphate having a C3-C5 alkyl group and a di(alkylpheny1) phenyl
phosphate having two C3-C5 alkyl groups, wherein the content of the
phosphorus compound is 0.01 to 5% by mass based on the total amount
15 of the refrigerating machine oil; and a hydrocarbon refrigerant having 2
to 4 carbon atoms. The refrigerating machine oil contained in the
working fluid composition for a refrigerating machine of the present
embodiment is the same as the refrigerating machine oil according to
first embodiment described above, and hence redundant description will
20 be herein omitted.
[0044] Specific examples of the hydrocarbon refrigerant having 2 to 4
carbon atoms of the present embodiment include ethane, propane,
n-butane and isobutane. In particular, a hydrocarbon refrigerant such
as isobutane (R600a) which has been used for a cold storage chamber,
25 and propane (R290) which has been examined for practical use for a
room air-conditioner can be suitably used in the present embodiment.
Particularly, the working fluid composition for a refrigerating machine
of the present embodiment can achieve the power saving by lowering
the viscosity of the refrigerating machine oil, and therefore is suitable to
be used for a cold storage chamber in which a reciprocating compressor,
5 where this effect is largely shown, is mainly used, and more particularly,
is suitable to be used for an isobutane refrigerant.
[0045] In the working fluid composition for a refrigerating machine of
the present embodiment, a content ratio between the refrigerant and the
refrigerating machine oil is not especially limited, and the
10 refrigerantlthe refrigerating machine oil is preferably 10190 to 90110,
and more preferably 30170 to 70130.
Examples
[0046] The present invention will now be described in more details by
way of examples and comparative examples, and it is noted that the
15 present invention is not limited to the following examples.
[0047] [Examples 1 to 8 and Comparative Examples 1 to 61
In Examples 1 to 8 and Comparative Examples 1 to 6, the
following lubricating base oils and additives were used for preparing
refrigerating machine oils respectively having compositions shown in
20 Tables 1 to 4.
(A) Lubricating base oil
Al: Ester of pentaerythritol and mixed acid of 2-ethyl hexanoic
acid and 3,5,5-trimethyl hexanoic acid (in a mass ratio of 1:l) (having a
kinematic viscosity at 40°C of 68.0 rnm2/s, a viscosity index of 90, a
25 pour point of -40°C and a flash point of 260°C)
A2: Dioctyl sebacate (having a kinematic viscosity at 40°C of
11.6 d s , a viscosity index of 150, a pour point of -50°C and a flash
point of 220°C)
A3: Polyoxypropylene having both ends ether-blocked with a
methyl group (having an average molecular weight of 1000, a kinematic
5 viscosity at 40°C of 46.0 mm2/s, a viscosity index of 190, a pour point
of -45°C and a flash point of 21 8°C)
A4: Paraffin refined mineral oil (having a kinematic viscosity at
40°C of 22.0 rnm2/s, a viscosity index of 95, a pour point of -15°C and a
flash point of 210°C)
10 A5: Linear alkylbenzene (having a kinematic viscosity at 40°C
of 8.1 mm2/s, a viscosity index of 45, a pour point of -50°C and a flash
point of 154°C)
(B) Phosphorus compound represented by formula (2)
B 1 : Mono(\ n-butylphenyl) diphenyl phosphate
15 B2: Di(isopropylpheny1) phenyl phosphate
B3: Mixture of mono(tert.-butylphenyl) diphenyl
phosphate/di(tert.-butylphenyl) phenyl phosphate = 65/35 (in a mass
ratio)
(C) Another additive
20 C1: Oiliness agent: glycerol monooleate (GMO)
C2: Anti-wear agent: triphenyl phosphate (TPP)
C3: Anti-wear agent: tricresyl phosphate (TCP)
[0048] Next, the refrigerating machine oils of Examples 1 to 8 and
Comparative Examples 1 to 5 were used for performing the following
25 lubricity test and thermal stability test:
[0049] (Lubricity test)
A friction and wear test was performed by using a Falex
block-on-ring friction and wear tester of ASTM D-2714-88 with a block
test piece of alloy tool steel SKS3 (JIS G4404) and a ring test piece of
nickel-chrome molybdenum steel SNCM220 (JIS G4103) under test
5 conditions of a load of 300 N, a peripheral speed at 0.1 rnls, a
temperature at 50°C and a test time: 30 min. The amount of a sample
oil was 100 ml, and for simulating dilution with a hydrocarbon
refrigerant, 20 ml of normal-decane, which is a hydrocarbon not
gasifying, was added to dilute the sample oil into a total sample amount
10 of 120 ml.
As the test results, a value of a friction coefficient when
stabilizing in a latter half of the test (about 25 min) is shown as the
friction coefficient, and an wear width (mm) on the block measured
after the test with Gmicroscope having a scale is shown as the result of
15 the wear test. The obtained results are shown in Tables 1 to 4.
[0050] (Thermal stability test)
Ninety grams of each sample oil having been adjusted to a
moisture content of 100 ppm or less was weighed out in an autoclave,
and a catalyst (a wire of iron, copper or aluminum, all having an outer
20 diameter of 1.6 mm x 50 mm) and 10 g of an isobutane refrigerant were
sealed therein. The resultant was heated to 175OC, and after 100 hours,
the appearance and an acid value (JIS C2100) of the sample oil were
measured. The obtained results are shown in Tables 1 to 4.
Incidentally, before the thermal stability test, the acid value of all the
25 sample oils (fresh oils) was 0.01 mgKOWg.
[0051] [Table 11
[0052] [Table 21
stability
Appearance of oil
Thermal
tngKOWg
Acid value,
mgKOH/g
Item Example 8
0.01
-
Example 5
0.01
Example 6
0.01
Example 7
0.01
[0053] [Table 31
Comparative
Example 1
Comparative Comparative
Example 2 I Example 3 1
Base oil
Content. mass% 1 100
Additive C2, mass% - 2.0
C3. mass%
Lubricity
Thermal
stability
I Friction coefficient
Wear width, mm
Appearance of oil
Acid value, mgKOH/g
precipitation -- precipitation precipitation
0.01
[0054] [Table 41
I Item
Comparative
Example 4
Comparative Comparative
Example5 I Example6 I
Additive 1 C2, mass% I 1 . 0 1
Base oil
Type
Content, mass%
C1, mass%
Lubricity
Thermal
stability
A4
99.9
0.1
C3, mass%
Friction coefficient
Wear width, tm
Appearance of oil
Acid value, mgKOH/g
A4
99.0
0.12
0.72
A5
99.5
No
precipitation
0.01
-
0.17 1
0.55
0.5
0.6
0.58
No
precipitation
0.01
No
precipitation
0.01
[0055] As shown in Tables 1 and 2, the refrigerating machine oils of
Examples 1 to 8 showed results of smaller friction coefficients and
smaller wear widths as compared with the refrigerating machine oil of
Comparative Example 1.
Next, through comparison between Examples 1 to 8 and
Comparative Examples 2 and 4, the wear width which is an index of the
wear was much larger in Comparative Examples 2 and 4. This result
supports that the oiliness agent of the adsorption type can attain a
friction coefficient at a given level but is inferior in the wear resistance.
10 Besides, through comparison between Examples 1 to 8 and
Comparative Examples 3, 5 and 6, the friction coefficient was higher by
about 20% in Comparative Examples 3,5 and 6 than in Examples 1 to 8.
This is a significant difference from the viewpoint of the power saving
of a refrigerating machine compressor. t
1
15 It is understood from these results that each of the refrigerating
machine oils of Examples 1 to 8 is a refkigerating machine oil that has
good stability, has, with respect to the lubricity, high wear resistance
even if diluted with a hydrocarbon, and can retain a friction coefficient
low.
20 Industrial Applicability
[0056] In the movement toward replacing a refrigerant for a
refrigerating machine with one having a lower global warming potential,
i.e., a lower GWP, due to the regulation against the currently used HFC
refrigerants, even in use together with a hydrocarbon refrigerant, that is,
25 one of alternative candidates for the HFC refrigerants, the refrigerating
machine oil of the present invention can be suitably used as an oil
capable of power saving and having long-term reliability, because of its
high wear resistance and the characteristic capable of retaining a friction
coefficient low, in a cold storage chamber, a room air-conditioner, a
general industrial reeigerator and the like, part of which already
5 practically use a hydrocarbon refrigerant.
CLAlMS
1. A working fluid composition for a refrigerating machine
comprising:
a refrigerating machine oil comprising at least one lubricating
5 base oil selected from a mineral oil and a synthetic oil, and at least one
phosphorus compound selected from a mono(alkylpheny1) diphenyl
phosphate having a C3-C5 alkyl group and a di(alkylpheny1) phenyl
phosphate having two C3-C5 alkyl groups, wherein a content of the
phosphorus compound is 0.01 to 5% by mass based on a total amount of
10 the refrigerating machine oil; and
a hydrocarbon refrigerant having 2 to 4 carbon atoms.
2. The working fluid composition for a refrigerating machine
according to claim 1, wherein the phosphorus compound is at least one
selected from a mono(butylpheny1) diphenyl phosphate having a C4
15 alkyl group and a di(butylpheny1) phenyl phosphate having two C4
alkyl groups.
3. The working fluid composition for a refrigerating machine
according to claim 1 or 2, wherein the lubricating base oil is at least one
selected from a mineral oil, an alkylbenzene, a poly-a-olefin, an ester
20 and an ether, and a kinematic viscosity at 40°C of the lubricating base
oil is 3 to 500 mm2/s.
4. The working fluid composition for a refrigerating machine
according to any one of claims 1 to 3, wherein the lubricating base oil is
at least one or more selected from a mineral oil, an alkyl benzene, a
25 poly-a-olefm, a diester, a polyol ester, a complex ester, a polyalkylene
glycol, a polyalkylene glycol compound and a polyvinyl ether, and a
kinematic viscosity at 40°C of the lubricating base oil is 3 to 300 mm2/s.
5. The working fluid composition for a refrigerating machine
according to any one of claims 1 to 4, wherein the hydrocarbon
refkigerant is at least one selected from propane, propylene,
5 normal-butane and isobutane.
6. A refrigerating machine oil comprising:
at least one lubricating base oil selected from a mineral oil and a
synthetic oil; and
at least one phosphorus compound selected from a
10 mono(alkylpheny1) diphenyl phosphate having a C3-C5 alkyl group and
a di(alkylpheny1) phenyl phosphate having two C3-C5 alkyl groups,
wherein a content of the phosphorus compound is 0.01 to 5% by mass
I
b ~ eodn a total amount of the refrigerating machine oil,
the refrigerating machine oil being used together with a
15 hydrocarbon refrigerant having 2 to 4 carbon atoms.