DESCRIPTION
Title of Invention: REFRIGERATOR OE, AND WORKING FLUID
COMPOSITION FOR REFRIGERATORS
Technical Field
5 [0001] The present invention relates to a refrigerating machine oil, a
working fluid composition for a refrigerating machine, use of a
composition containing polyalkylene glycol as a refligerating machine
oil for a mildly flammable hydrofluorocarbon refrigerant or a working
fluid composition for a refrigerating machine containing a mildly
10 flammable hydrofluorocarbon refrigerant, and application of
polyalkylene glycol for producing a refrigerating machine oil for a
mildly flammable hydrofluorocarbon refrigerant or a working fluid
-
composition for a refrigerating machine containing a mildly flammable
hydrofluorocarbon refrigerant, a method for flame-retarding a
15 refrigerating machine.
Background Art
[0002] CFCs (chlorofluorocarbons) and HCFCs
(hydrochlorofluorocarbons), which have been conventionally used as
rekigerants for refrigeration equipment, have become objects of
20 regulations due to the problem of recent ozone layer depletion, and
HFCs (hydrofluorocarbons) are used as refrigerants instead of them.
[0003] In the case where a CFC or HCFC is as a refrigerant,
hydrocarbon oils such as mineral oil and alkylbenzenes have been used
suitably as a refrigerating machine oil. However, depending the type
25 of the coexistent refrigerant, the refrigerating machine oil may exhibit
unpredictable behavior, such as compatibiity with the refrigerant,
lubricity, solution viscosity with the re~igerant, and thermal and
chemical stability, and therefore the refrigerating machine oil needs to
be developed for each refrigerant. Thus, as refkigerating machine oils
for an HFC refrigerant, for example, polyalkylene glycol (see Patent
5 Literature l), ester (see Patent Literature 2), carbonic acid ester (see
Patent Literature 3), and polyvinyl ether (see Patent Literature 4) have
been developed.
Citation List
Patent Literature
10 [0004] Patent Literature 1: Japanese unexamined Patent PublicationNo.
H02-242888
Patent Literature 2: Japanese unexamined Patent Publication No.
H03-200895
Patent Literature 3: Japanese unexamined Patent Publication No.
15 H03-217495
Patent Literature 4: Japanese unexamined Patent Publication No.
HO6-128578
Summary of Invention
Technical Problem
20 [0005] It is an object of the present invention to provide a refkigerating
machine oil of which safety has been enhanced fkom the viewpoint of
flame retardancy and a working fluid composition for a refkigerating
machine containing the rekigerating machine oil.
Solution to Problem
25 [0006] To solve the above problem, the present invention provides a
refkigerating machine oil comprising a polyalkylene glycol represented
by the following formula (1):
R'-(oR~),-oR~ (1)
[R' and RZ may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having from 1 to 5 carbon
5 atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
polyalkylene glycol represented by the formula (1) is from 1000 to
2500]
10 the polyalkylene glycol having a ratio of the weight average
molecular weight Mw to the number average molecular weight Mu,
Mw/Mn, of from 1 .OO to 1.1 5, the refrigerating machine oil being used
with a mildly flammable hydrofluorocarbon refrigerant.
[0007] In the polyalkylene glycol represented by the formula (I), it is
15 preferred that the ratio of an ethylene group in the alkylene groups
represented by R3 is 40 mol% or less.
[0008] Also, the present invention provides a working fluid
composition for a refrigerating machine which comprises the above
refrigerating machine oil and a mildly flammable hydrofluorocarbon
20 refrigerant.
[0009] In the present invention, the mildly flammable
hydrofluorocarbon refijgerant may contain at least one selected from the
group consisting of 1,3,3,3-tetrafluoropropene and
2,3,3,3 -tetrafluoropropene.
25 [0010] It may also be said that the present invention is use of a
composition for a refrigerating machine oil or a working fluid
coinposition for a refrigerating machine, the composition comprising a
polyalkylene glycol represented by the following fo~mula(1 ):
R'-(oR~)~oR~ (I)
[R' and R2 may be the same or different from each other and each
5 represent a hydrogen atom, an alkyl group having from 1 to 5 carbon
atoms, or an acyl group having from 2 to 5 carbon atoms, R~ represents
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
polyalkylene glycol represented by the formula (1) is from 1000 to
10 25001
the polyallcylene glycol having a ratio of a weight average
molecular weight Mw to the number average molecular weight Mn,
MwtMn, of from 1 .OO to 1.15,
the refrigerating machine oil being used with a mildly
15 flammable hydrofluorocarbon reftigerant,
the working fluid composition comprising a mildly flammable
hydrofluorocarbon refrigerant.
[0011] It may also be said that the present invention is use of a
polyalkylene glycol for manufacturing a refi-igerating machine oil or a
20 working fluid composition for a refrigerating machine, the polyalkylene
glycol being represented by the following formula (1):
R'-(0R3),-OR' (1)
[R' and R2 may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having from 1 to 5 carbon
25 atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
polyalkylene glycol represented by the formula (I) is from 1000 to
25001
the polyalkylene glycol having a ratio of a weight average
5 molecular weight Mw to the number average molecular weight Mn,
MwiMn, of from 1.00 to 1.15,
the refrigerating machine oil being used with a mildly
flammable hydrofluorocarbon refrigerant
the working fluid composition comprising a mildly flammable
10 hydrofluorocarbon refrigerant.
[0012] The present invention also provides a method for
flame-retarding a refrigerating machine with a mildly flammable
hydrofluorocarbon refiigerant, the method comprising flame-retarding
the refrigerating machine by using a composition as a refrigerating
15 machine oil, the composition comprising a polyalkylene glycol
represented by the following formula (1):
R'-(oR~),-oR~ (1)
[R' and R' may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having from 1 to 5 carbon
20 atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
polyalkylene glycol represented by the formula (1) is from 1000 to
25001
25 the polyalkylene glycol having a ratio of the weight average
molecular weight Mw to the number average molecular weight Mn,
Mw/Mn, of from 1.00 to 1.15.
Advantageous Effects of Invention
[0013] According to the present invention, it is possible to provide a
refrigerating machine oil of which safety has been enhanced from the
5 viewpoint of flame retardancy and a working fluid composition for a
refrigerating machine containing the refrigerating machine oil.
Brief Descripfioli of Drawings
[0014] [Figure 11 Figure 1 is a schematic view showing an example of
the configuration of a refrigerating machine.
10 Description of Embodiments
[0015] Hereinafter, preferred embodiments of the present invention are
described in detail.
[0016] A refrigerating machine oil according to the present embodiment
comprises a polyalkylene glycol represented by the following formula
15 (1):
R'-(oR~)>,oR~ (1)
and R' may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having from 1 to 5 carbon
atoms, or an acyl group having f?om 2 to 5 carbon atoms, R3 represents
20 an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
polyalkylene glycol represented by the formula (1) is from 1000 to
25001
wherein the polyalkylene glycol has a ratio of the weight average
25 molecular weight Mw to the number average molecular weight Mtl,
MwM, of from 1.00 to 1.15 (hereinafter, referred to as "the
FP14-0437-00
polyalkylene glycol according to the present embodiment"), and
wherein the refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refiigerant. A working fluid composition for a
rekigerating machine according to the present embodiment comprises a
5 refrigerating machine oil which comprises a polyalkylene glycol
represented by the formula (I), wherein the polyalkylene glycol has a
ratio of the weight average molecular weight Mw to the number average
molecular weight Mn, Mw/Mn, of from 1.00 to 1.15, and a mildly
flammable hydrofluorocarbon refiigerant. The working fluid
10 composition for a refrigerating machine according to the present
embodiment includes an aspect comprising a refrigerating machine oil
according to the present embodiment and a mildly flammable
hydrofluorocarbon rekigerant.
[0017] In the above formula (I), R' and R~ may he the same or different
15 from each other and each represent a hydrogen atom, an alkyl group
having from 1 to 5 carbon atoms, or an acyl group having from 2 to 5
carbon atoms. In the case where R' and R~ ase each an alkyl group or
an acyl group, they may be a linear one or a branched one. Examples
of such an alkyl group specifically include a methyl group, an ethyl
20 group, a linear or branched propyl group, a linear or branched butyl
group, and a linear or branched pentyl group and the like, and examples
of the acyl group specifically include an acetyl group, a linear or
branched propanoyl group, a linear or branched butanoyl group, and a
linear or branched pentanoyl group and the like. Of these alkyl groups
25 and acyl groups, from the point of the compatibility with the refrigerant,
a methyl group, an ethyl group, a linear or branched propyl group, a
linear or branched butyl group, an acetyl group, a linear or branched
propanoyl group, a linear or branched butanoyl group is more preferred,
a methyl group, an ethyl group, or an acetyl group is fusther preferred,
and a methyl group or an acetyl group is most preferred. If the alkyl
5 group or the acyl group has 5 or less carbon atoms, the composition
range which exhibits compatibility to the refkigerant becomes wider,
and it is possible to suppress lubrication defects of a refrigerant
compressor and inhibition of heat exchange in an evaporator.
[0018] In the above formula (I), R3 represents an alkylene group having
10 from 2 to 4 carbon atoms. Examples of such an alkylene group
specifically include an ethylene group (-CH2CH2-), a propylene group
(-CH(CH3)CH2-), a trimethylene group (-CH2CH2CH2-), a butylene
-
group (-CH(CH2CH3)CH2-), and a tefxarnethylene group
(-CH2CH2CH2CH2-). Of these alkyIene groups, an ethylene group, a
15 propylene group, a butylene group, and a tetra methylene group are
more preferred. The ratio of the alkylene group having 2 carbon atoms
(that is, an ethylene group) in the alkylene groups represented by R3 is
preferably 40 mol% or less, more preferably 30 mol% or less, further
preferably 25 mol% or less, and most preferably 20 mol% or less. The
20 case where the ratio of the allcylene group having 2 carbon atoms
(ethylene group) is 40 mol% or less is prefened because tlie refrigerant
compatibility is excellent.
[0019] The number average molecular weight (MI) of the polyalkylene
glycol according to the present embodiment can be, for example, &om
25 500 to 3000, and can be from 600 to 2000 and can be from 600 to 1500.
The number average molecular weight (Mn) of the polyalkylene glycol
according to the present embodiment is preferably from 1500 to 2500,
more preferably from 15 10 to 2300, and further preferably &om 1520 to
2100. n in the foimula (1) is an integer such that the number average
molecular weight of the polyalkylene glycol satisfy the above condition,
5 In the case where the number average molecular weight of the
polyallqlene glycol is the above lower limit or more, the lubricity is
enhanced under coexistence of a mildly flammable hydrofluorocarbon
refkigerant. In the case where the number average molecular weight of
the polyalkylene glycol is the above upper limit or less, the composition
10 range which exhibits compatibility to the mildly flammable
hydrofluorocarbon refrigerant becomes wider under low temperature
conditions, and it is possible to suppress lubrication defects of a
refrigerant compressor and inhibition of heat exchange in an evaporator.
[0020] In the polyalkylene glycol according to the present embodiment,
15 the ratio of the weight average molecular weight (Mw) to the number
average molecular weight (Mn) (Mw/Mn) is from 1.00 to 1.15,
preferably from 1.00 to 1.14, more preferably &om 1.00 to 1.13, and
further preferably from 1.00 to 1.12. If MwMn is 1.15 or less, it is
possible to increase the flash point and the autoignition point of the
20 polyalkylene glycol. If Mw& is 1.15 or less, it is possible to ensure
the compatibility between the mildly flammable hydrofluorocarbon
refrigerant and the refrigerating machine oil. Mnr/Mn can be 1.02 or
more, 1.04 or more, 1.06 or more, or 1.08 or more, from the viewpoint
of increasing the lubricity of the refrigerating machine oil. The weight
25 average molecular weight (Mw) of the polyalkylene glycol according to
the present embodiment is selected as appropriate such that Mn and
MwMn satisfy the above conditions.
[0021] The weight average molecular weight (Mw), the number
average molecular weight (Mn), and the ratio of the weight average
molecular weight (Mw) to the number average molecular weight (Mn)
5 (Mw/Mn) in the present invention mean Mw, Mn, and Mw/Mn obtained
by GPC analysis (values in terms of polypropylene glycol (standard
sample)). It is possible to measure Mw, Mn, and MwIMn, for
example, as follows.
[0022] Chloroform is used as the solvent, and dilution is conducted to
10 prepare a solution of which sample concentration is 1% by mass. The
sample solution is analyzed by using a GPC apparatus (Waters Alliance
2695). Analysis is conducted at a solvent flow rate of 1 ml/min by
using a column of which analyzable molecular weight is &om 100 to
10,000 with the refractive index as the detector. It should be noted
15 that, after the relationship between the column retention time and the
molecular weight by using a polypropylene glycol standard of which
molecular weight is obvious is determined to thereby form a calibration
curve separately, the molecular weight is determined from the obtained
retention time.
20 [0023] It is preferred that the flash point of the polyalkylene glycol
according to the present embodiment is 220°C or more, it is more
prefemed that the flash point is 230°C or more, and it is further preferred
that the flash point is 240°C or more. The flash point in the present
invention means the flash point measured in colnpliance with JIS
25 K2265-4:2007 "Determination of flash points - Part4: Cleveland open
cup method",
[0024] It is preferred that the autoignition point of the polyalkylene
glycol according to the present embodiment is 330°C or more, it is more
preferred that the autoignition point is 340°C or more, and it is further
prefemed that the autoignition point is 350°C or more. The
5 autoignition point in the present invention means the value measured by
the method in compliance with ASTM E 659-1978.
[0025] The kinematic viscosity of the polyalkylene glycol according to
the present embodiment at 100°C is preferably fiom 4 to 30 mm2/s,
more preferably fiom 5 to 20 mm2/s, further preferably &om 6 to 18
10 mm2/s, still further preferably fiom 7 to 16 mm2/s, particularly
preferably &om 8 to 15 m d s , and most preferably &om 10 to 15
mm2/s. If the kinematic viscosity at 100°C is the above lower limit or
more, the lubricity under coexistence of the refiigerant increases. If
the kinematic viscosity is the above upper limit or less, the composition
15 range which exhibits compatibility to the refiigerant becomes wider and
it is possible to suppress lubrication defects of the refiigerant
compressor and inhibition of heat exchange in the evaporator.
[0026] It is preferred that the kinematic viscosity of the polyalkylene
glycol according to the present embodiment at 40°C is fiom 10 to 200
20 m d s , and it is more preferred that the kinematic viscosity is &om 20 to
150 mm2/s. If the kinematic viscosity at 40°C is 10 mm2/s or more, the
lubricity and the sealabiliw of the compressor tend to increase. If the
kinematic viscosity is 200 mm2/s or less, the composition range which
exhibits compatibility to the refiigerant becomes wider under low
25 temperature conditions, and it is possible to suppress lubrication defects
of the refiigerant compressor and inhibition of heat exchange in the
evaporator.
[0027] The kinematic viscosity in the present invention means the
kinematic viscosity specified in JIS K-2283-1993.
[0028] It is preferred that the pour point of the polyalkylene glycol
5 accosding to the present embodiment is -10°C or less, and it is more
preferred that the pour point is fiom -20 to -50°C. If a polyalkylene
glycol of which pour point is -10°C or less is used, it tends to be able to
suppress the refrigerating machine oil in a refkigerant circulation system
from solidifjing at low temperatures. The pour point in the present
10 invention means the pour point specified in JIS K2269-1987.
[0029] The hydroxy value of the polyalkylene glycol according to the
present embodiment is, but not pasticularly limited to, preferably 100
mgKOH/g or Less, more preferably 50 mgKOWg or less, further
preferably 30 mgKOH/g or less, and most preferably 10mgKOWg or
15 less.
[0030] The polyalkylene glycol according to the present embodiment
can be synthesized by using a known method (for example, see
"Alkylene Oxide Polymers", Shibata, M. et al., Kaibundo, published on
Nov. 20, 1990 (Hei 2)). For example, a polyalkylene glycol
20 represented by the above formula (1) is obtained by subjecting an
alcohol (R'OH; R' represents the same definition as R' in the above
formula (I)) to addition polymerization with one or more predeteimined
alkylene oxides and further etheri%ing or esterifying the terminal
hydroxyl groups. In the case where two or more different alkylene
25 oxides are used in the production step described above, the obtained
polyalkylene glycol may be either a random copolymer or a block
copolymer, but it is preferred to be a block copoly~fiefrr om the point of
tendency to more excel in oxidation stability, and it is preferred to be a
random copolymer from the point of tendency to more excel in low
temperature flowability.
5 [0031] In the production step of the polyalkylene glycol according to
the present embodiment, there is a case where an alkylene oxide such as
propylene oxide causes a side reaction to thereby form an unsaturated
group such as an ally group in the molecule. If an unsaturated group is
formed in a polyalkylene glycol molecule, phenomena, such as
10 decreases in the thermal stability of the polyallqlene glycol itself,
formation of sludge caused by fo~mtiono f a polymerized product, or
formation of a peroxide due to decreases in the anti-oxidative property
(oxidation prevention property), are likely to occur. In particular, if a
peroxide is formed, the peroxide is decomposed to form a compound
15 having a carbonyl group, furthermore, the compound having a carbonyl
group form sludge, and clogging of a capillary is likely to occur.
[0032] Accordingly, as the polyalkylene glycol according to the present
embodiment, those of which degree of unsaturation due to an
unsaturated group and the like is low are preferred. Specifically, it is
20 preferred that the degree of unsatwation is 0.04 meqlg or less, it is more
prefel~edth at the degree of unsaturation is 0.03 meqlg or less, and it is
hrther preferred that the degree of unsaturation be 0.02 meq/g or less.
It is preferred that the peroxide value be 10.0 meqkg or less, it is more
preferred that the peroxide value be 5.0 meqkg or less, and it is mher
25 preferred that the peroxide value be 1.0 meqkg. Furthermore, it is
preferred that the carbonyl value is 100 ppm by weight or less, it is
more preferred that the carbonyl value is 50 ppm by weight or less, and
it is further preferred that the carbotiyl value is 20 ppm by weight or
less.
[0033] The degree of unsaturation, peroxide value and carbonyl value
5 in the invention are the values measured each in accordance with the
Standard Methods for the Analysis of Fats, Oils and Related Materials
established by the Japan Oil Chemists' Society. That is, the degree of
unsaturation in the present invention is a value (meqlg) obtained by
reacting a Wijs solution (IC1-acetic acid solution) with a sample, leaving
10 the reaction mixture to stand in a dark place, subsequently reducing the
excess ICl to iodine, titrating the iodine portion with sodium thiosulfate
to calculate the iodine value, and then converting the iodine value to
vinyl equivalents (meqfg). The peroxide value in the present invention
is a value (meqtkg) obtained by adding potassium iodide to a sample,
15 titrating the produced free iodine with sodium thiosulfate, and
converting the free iodine to milliequivalents with respect to 1 kg of
sample. The carbonyl value in the present invention is a value (ppm
by weight) obtained by allowing 2,4-dinitrophenylhydrazine to act on a
sample to produce colorable quinoid ions, measuring the absorbance of
20 this sample at 480 nm, and converting it to a cwbonyl content based on
a predetermined calibration curve with cinnamaldehyde as the standard
substance.
[0034] In the present embodiment, in order to obtain a polyalkylene
glycol of which degree of unsaturation, peroxide value and carbonyl
25 value are low, it is preferred that the reaction temperature in allowing
the alkylene oxide to react be 120°C or less, and it is more preferred that
the reaction temperature is llO°C or less. If an alkali catalyst is used
during production, it is possible to reduce the degree of unsaturation by
using an inorganic adsorbent such as activated casbon, activated white
ea~thb, entonite, dolomite, or alurninosilicate for removing the catalyst.
5 It is possible to prevent the increase in the peroxide value or carbonyl
value also by avoiding contact with oxygen as much as possible and by
adding an antioxidant during production or use of the polyalkylene
glycol.
[0035] The refrigerating machine oil of the present embodiment
10 comprises the above polyalkylene glycol, and even in the case where the
polyalkylene glycol is used singly, it is possible to enhance the safety
for a refrigerating machine oil and a working fluid composition for a
refrigerating machine containing the refiigerating machine oil, fsom the
viewpoint of flame retardancy. However, base oils described below
15 other than the above polyalkylene glycol and additives may be added as
required.
[0036] The content of the above polyalkylene glycol in the refrigerating
machine oil of the present embodiment is not particularly limited
provided that the above excellent properties are not impaired, but, based
20 on the total amount of the refrigerating machine oil, it is preferred the
content is 50% by mass or more, it is more preferred that the content be
70% by mass or more, it is fhther preferred that the content be 80% by
mass or more, and it is particularly prefel~edth at the content be 90% by
mass or more. If the content of the above polyalkylene glycol is 50%
25 by mass or more, it is possible to enhance the safety ofthe refrigerating
machine oil and the working fluid composition for a reEigerating
machine containing the refiigerating machine oil.
[0037] As the base oil other than the polyalkylene glycol according to
the present embodiment, it is possible to use hydrocarbon oils, such as
mineral oils, olefin polymers, naphthalene compounds, and
5 alkylbenzenes, and ester-based base oils (such as monoesters, diesters,
and polyol esters), and oxygen-containing synthetic oils, such as
polyglycols other'than the polyalkylene glycol according to the present
embodiment, polyvinyl ethers, ketones, polyphenyl ethers, silicones,
polysiloxanes and perfluoroethers. As the oxygen-containing synthetic
10 oil, polyol esters and polyvinyl ethers are preferably used.
[0038] The refrigerating machine oil and the working fluid composition
for a refiigerating machine of the present embodiment can comprise
conventionally-known additives for refrigerating machine oil as
required, in order to hrther enhance their performance. Examples of
15 such additives include antioxidants, acid scavengers, antiwear agents,
extreme pressure agents, oiliness agents, antifoaming agents, metal
deactivators, viscosity index improvers, pour point depressant, and
detergent dispersants. One of these additives may be used singly, or
two or more of these additives may be used in combination. The
20 content of these additives is not particularly limited to, but it is
preferably 10% by mass or less and firther preferably 5% by mass or
less, based on the total amount of the refrigerating machine oil.
[0039] The kinematic viscosity of the refiigerating machine oil of the
present embodiment at 40°C is not particularly limited to, but it is
25 preferably from 3 to 1000 nun2/s, more preferably from 4 to 500 mm2/s,
and further preferably from 5 to 400 d s . The kinematic viscosity
of the refiigerating machine oil of the present embodiment at 100°C is
preferably ftom 1 to 100 mm2/s and more preferably &om 2 to 50
mm2/s.
[0040] The moisture content of the refiigerating machine oil of the
5 present embodiment is not particularly limited to, but it is preferably
500 ppm or less, more preferably 300 ppm or less, and further
preferably 200 ppm or less, based on the total amount of the
refrigerating machine oil. Particularly, in the case of being used for a
hermetic refrigerating machine, it is required that the moisture content is
10 low, from the viewpoint of the influence on thermallchemical stability
and the electrical insulation property of the refkigerating machine oil.
[0041] The acid value of the refrigerating machine oil of the present
embodiment is not particularly limited to, but it is preferably 0.1
mgKOH/g or less and more preferably 0.05 mgKOWg or less, in order
15 to prevent corrosion of the metal used in the refrigerating machine or
piping, and to prevent degradation of the ester contained in the
refrigerating machine oil of the present embodiment. The acid value in
the present invention means the acid value measured in compliance with
JIS K2501: 2003 "Petroleum Products And Lubricating
20 Oils-Neutralization Value Test Method".
[0042] The ash content of the refrigerating machine oil of the present
embodiment is not particularly limited to, but it is preferably 100 ppm
or less and more preferably 50 ppln or less, in order to increase the
thermal/chemical stability of the reftigerating machine oil and to
25 suppress the occutTence of sludge or the like. The ash content in the
present invention nieans the value of the ash content measured in
compliance with JIS K2272: 1998 "Crude Oil/Petroleum Product-Ash
Content and Sulfated Ash Content Test Method".
[0043] The refrigerating machine oil of the present embodiment is used
with a mildly flammable hydrofluorocarbon (HFC) refrigerant, and the
5 working fluid colnposition for a refrigerating machine of the present
embodiment comprises a mildly flammable hydrofluorocarbon (HFC)
refrigerant. In the hydrofluorocarbon (£PC) refrigerant, saturated
fluorinated hydrocarbon refrigerants (also refelred to as
hydrofluoroalkane refrigerants) and unsaturated fluorinated
10 hydrocarbon refrigerants (also refel~ed to as hydrofluoroalkene
refrigerants, hydrofluoroolefin refrigerants, or HYO refrigerants) are
included. The mildly flammable refrigerant in the present invention
means refrigerants included in the A2L classification in the flammability
classification of ASHRAE (The American Society of Heating,
15 Refrigerating and Air-conditioning Engineers).
[0044] Examples of the mildly flammable hydrofluorocarbon
refrigerant include difluoromethane (HFC-32),
1,3,3,3-tetrafluoropropene (FPC-l234ze), and
2,3,3,3-tetrafluoropropene (HFC- 1234yf). As the mildly flammable
20 hydrofluorocarbon refrigerant, 1,3,3,3 -tetrafluoropropene
(HFC- 1234ze) or 2,3,3,3-tetrafluoropropene (WC-1234yf) is preferred.
[0045] The refrigerant used with the refrigerating machine oil of the
present embodiment may be a mixed refrigerant of a mildly flammable
hydrofluorocarbon refrigerant and other refrigerant. Examples of other
25 refrigerants include hydsofluorocarbon refrigerants other than mildly
flammable hydrofluorocarbon refiigerants, fluorine-containing
ether-based refrigerants such as perfluoroethers,
bis(trifluoromethyl)sulfide refrigerants, ixifluoromethyl iodide
refrigerants, and natural refrigerants, such as dimethylether, carbon
dioxide, ammonia, and hydrocarbons. As other refrigerants,
5 refrigerants composed of a compound which does not have an oxygen
atom are preferably used.
COO461 Examples of hydrofluorocarbon refrigerant other than the mildly
flammable hydrofluorocarbon refrigerant include trifluoromethane
(HFC-23), pentafluoroethane (HFC-1 25), 1,1,2,2-tetrafluoroethane
10 (HFC-134), 1,1,1,2-tetrafluoroethane @PC-134a), 1 ,l,l-trifluoroethane
(HFC-143a), 1,l-difluoroethane (HFC-152a), fluoroethane (HFC-161),
1,1,1,2,3,3,3-heptafluoropropane
-
(HIT-227ea),
1 ,I, 1,2,3,3-hexafluoropropane (HFC-236ea),
1,1,1,3,3,3-hexafluoropropane (HFC-23 6fa),
15 1,1,1,3,3-pentafluoropropane @FC-245fa), 1,1,1,3,3-pentafluorobutane
(IXFC-365mfc), and 1,2,3,3,3-pentafluoropropene (HFC-1225ye).
[0047] As the hydrocarbon refrigerant, hydrocarbons having i7om 3 to
5 carbon atoms are preferred, and specifically, examples include
methane, ethylene, ethane, propylene, propane, cyclopropane, normal
20 butane, isobutane, cyclobutane, methylcyclopropane, 2-methylbutane,
normal pentane, or mixtures of two or more of these. Of these, those
which ase gaseous at 25°C and 1 atmosphere are preferably used, and
propane, normal butane, isobutane, 2-methylbutane or a mixture of
these is preferred.
25 [0048] Examples of the fluorine-containing ether-based refrigerant
specifically include HFE-134p, HFE-245mc, HFE-236mf, HFE-236me,
HFE-3381ncf, HFE-365tncf, HFE-245mf, HFE-3471nmy, WE-347mcc,
HFE-125, HFE-143m, HFE-134m, and WE-227me, and these
refrigerants are selected as appropriate depending on uses and the
required performance.
5 LO0491 In the case where the refrigerant of the present embodiment is a
mixed refrigerant, it is preferred that the mixing ratio between the
mildly flammable hydrofluorocarbon refrigerant and other refrigerant
(mass ratio, mildly flammable hydrofluorocarbon refrigerant : other
reEigerant) is 1:99 to 99:1, and it is more prefeilced that the mixing ratio
10 is 5:9S to 95:5.
[0050] The refrigerating machine oil of the present embodiment is,
usually in a refrigerating machine, present in the form of a single mildly
flammable hydrofluorocarbon refrigerant or of a working fluid
composition for refrigerating machine mixed with a mixed refrigerant.
15 The mixing propoltion of refrigerating machine oil and the refrigerant in
the working fluid composition for a refrigerating machine of the present
embodiment is not particularly limited to, but refrigerating machine oil
is preferably from 1 to 500 parts by mass and more preferably from 2 to
400 parts by mass with respect to 100 parts by mass of the refrigerant.
20 [005 11 The refrigerating machine of the present embodiment comprises
at least a refrigerant circulation system comprising a refrigerant
compressor, a gas cooler, an expansion mechanism, and an evaporator.
Examples of the refrigerating machine include air conditioners for
automobiles, dehumidifiers, a refrigerating machine,
25 freezing-refrigerating warehouses, vending machines, showcases,
cooling apparatus for chemical plants or the like, air conditioners for
housing, package air conditioners, and heat pumps for supplying hot
water.
[0052] Figure 1 is a schematic view showing an example of the
configuration of a refrigerating machine according to the present
5 embodiment. As shown in Figure 1, a refrigerating machine 10, for
example, comprises at least a refrigerant circulation system in which a
refrigerant compressor 1, a gas cooler 2, an expansion mechanism 3 (a
capilliuy, an expansion valve and the like), and evaporator 4 are
successively connected by a passage 5. In the refiigerant circulation
10 system, fust, a mildly flammable hydrofluorocarbon refrigerant
(hereinafter, also simply referred to as "a refrigerant") at a high
temperature (usually 70 to 120°C) released from the rehigerant
compressor 1 into the passage 5 becomes a high-density fluid
(supercritical fluid or the like) in the gas cooler 2. Subsequently, the
15 refrigerant passes through the narrow passage possessed by the
expansion mechanism 3 to be liquefied, and is further vaporized in the
evaporator 4 to have a lower temperature (usually -40 to O°C).
[0053] In refrigerant compressor 1 in Figure 1, a small amount of the
refrigerant and the large amount of the refrigerating machine oil coexist
20 under a high temperature (usually 70 to 120°C) condition. The
refrigelant released hom the rehigerant compressor 1 to the passage 5 is
gaseous and contains a small amount of (usually 1 to 10%) the
refrigerating machine oil as mist. In this misty refrigerating machine
oil, a small amount of the refrigerant is dissolved (point a in Figure 1).
25 Next, in the gas cooler 2, the gaseous refrigerant is colnpressed to be a
high-density fluid, and under a relatively high temperature (usually 50
to around 70°C) condition, a large amount of the refi.igerant and a small
amount of the refiigerating machine oil coexist (point b in Figure 1).
Furthermore, the mixture of a large amount of the refrigerant and a
small amount of the refrigerating machine oil is successively supplied to
5 the expansion mechanism 3 and the evaporator 4 to rapidly have a lower
temperature (usually -40 to 0°C) (points c and d in Figure 1) and be
returned back to the refrigerant compressor 1.
[0054] By using a composition comprising the polyalkylene glycol
according to the present embodiment as the refrigerating machine oil, it
10 becomes possible to flame-retard the a refiigerating machine in which a
mildly flammable hydrofluorocarbon refrigerant as mentioned above is
used.
[0055] The refrigerating machine oil and the working fluid composition
for a refrigerating machine of the present embodiment are preferably
15 used in air conditioners or a reEigerating machine having a
reciprocating or rotating closed compressor, or in open or closed
automobile air conditioners. The refkigerating machine oil and the
working fluid composition for a refrigerating machine of the present
embodiment are preferably used in cooling apparatuses, such as
20 dehumidifiers, hot water suppliers, freezers, freezing-refrigerating
warehouses, vending machines, showcases, chemical plants and the like.
The refrigerating machine oil and the working fluid composition for a
refrigerating machine of the present embodiment are preferably used in
those having a centrifirgal compressor.
25 ExampIes
[0056] Hereinafter, the present invention is described more specifically
based on examples and comparative examples, but the present invention
is not in any way limited by the examples below.
[0057] [Examples 1 to 4 and Comparative Examples 1 to 61
In Examples 1 to 4 and Comparative Examples 1 to 6, base oils
5 1 to 10 shown below were each used to prepare a refrigerating machine
oil.
(00581 (Base oil)
Base oil 1:
Me-0-(PO),,-Me
10 [number average molecular weight Mn: 800, ratio of the weight average
molecular weight (Mw) to the number average molecular weight (Mn)
-
(Mw/Ivln): 1.08, ratio of the oxyethylene group in the total oxyalkylene
groups: 0 mol%]
Base oil 2:
15 Me-0-@O,PO),-Me
[number average molecular weight Mn: 800, ratio of the weight average
molecular weight (Mw) to the number average molecular weight (Mn)
(Mw&): 1.17, ratio of the oxyethylene group in the total oxyalkylene
groups: 10 mol%]
20 Base oil 3:
Me-0-(PO),-Me
[number average molecular weight Mn: 1500, ratio of the weight
average molecular weight (Mw) to the number average n~oleculm
weight (Mn) (MwIMn): 1 .lo, ratio of the oxyethylene group in the total
25 oxyalkylene groups: 0 mol%]
Base oil 4:
Me-0-@O,PO),-Me
[number average molecular weight Mn: 1500, ratio of the weight
average molecular weight (Mw) to the number average molecular
weight (Mn) (Mw/Mn): 1.05, ratio of the oxyethylene group in the total
5 oxyalkylene groups: 30 mol%]
Base oil 5:
Me-0-(PO),-Me
[number average molecular weight Mn: 1500, ratio of the weight
average molecular weight (Mw) to the number average molecular
10 weight (Mn) (Mwhfn): 1.18, ratio of the oxyethylene group in the total
oxyallcylene groups: 0 mol%]
Base oil 6:
Me-0-(EO,PO),-Me
[number average molecular weight Mn: 1500, ratio of the weight
15 average molecular weight (Mw) to the number average molecular
weight (Mn) (Mw/Mn): 1.21, ratio of the oxyethylene group in the total
oxyalkylene groups: 40 mol%]
Base oil 7:
Ac-0-PO),-AC
20 [number average molecular weight Mn: 1000, ratio of the weight
average molecular weight (Mw) to the number average molecular
weight (Mn) (Mw/Mn): 1.13, ratio of the oxyethylene group in the total
oxyalkylene groups: 0 mol%]
Base oil 8:
25 Me-0-(PO),-Me
[number average molecular weight Mn: 400, ratio of the weight average
molecular weight (Mw) to the number average molecular weight (Mn)
(Mw/Mn): 1.12, ratio of the oxyethylene group in the total oxyalkylene
groups: 0 mol%]
Base oil 9:
5 Me-0-(PO),-Me
[number average molecular weight Mu: 2300, ratio of the weight
average molecular weight (Mw) to the number average molecular
weight (Mn) (MwiMn): 1.14, ratio of the oxyethylene group in the total
oxyalkylene groups: 0 mol%]
10 Base oil 10:
Me-0-(EO, PO),-Me
[number average molecular weight Mn: 2700, ratio of the weight
average molecular weight (Mw) to the number average molecular
weight (Mu) (Mw/Mn): 1.27, ratio of the oxyethylene group in the total
15 oxyalkylene groups: 30 mol%]
[0059] In the base oils 1 to 10, Me represents a methyl group, Ac
represents an acetyl group, EO represents an oxyethylene group, and PO
represents a propylene group.
[OOGO] Next, on each refrigerating machine oil of Examples 1 to 4 and
20 Comparative Examples 1 to 6, evaluations shown below were
performed.
[OOGl] (Evaluation of various properties)
Various properties of the refrigerating machine oils were
evaluated in compliance with test methods shown below.
25 Kinematic viscosity: JIS K2283-1993
Pour point: JIS K2269-1987
Flash point: JIS K2265-4: 2007
Autoignition point: ASTME 659-1978
[0062] (Refrigerant compatibility evaluation)
In compliance with JIS-K2211: 2009 "Refrigerating machine
oils" and "Refrigerant compatibility test method", 2 g of the
refrigerating machine oil was added to 18 g of
2,3,3,3-tetrafluoropropene (HFC-1234yf) to observe whether the
refrigerant and the refligerating machine oil were dissolved in each
other at O°C. The results obtained are shown in Tables 1 to 2. In the
tables, "compatible" means that the refrigerant and the refrigerating
machine oil were dissolved in each other, and "separated" means that
the refrigerant and the refrigerating machine oil were separated into two
layers.
[Table 11
1 Exa~nple 1 I Example 2 I Example 3 I Example 4
Base oil No. I 3 I 4 I 7 I 9
Kinematic viscosity
[0064]
[Table 21 1 ~~~i~ 1 1 ~ x a ~ b
Base oil No.
Mw/Mn ( 1.08 1 1.17
EO ratio iniol%l I o 10
HFC- HFCRefiigeranf
1234yf 1234yf
~~ -
I viscosity
[mm2/s] l0O0C 10 10
pour ~oinrto ci I 4 5 I <-45
Flash point [OC] I 209 1 203
Autoignition point
r a m 1 345 1 339
0 40 1 0 30
mc- I HFC- I HFC- I HFCComp.
Example 3
5
[0065] In the case where the refrigerating machine oils of Examples 1
to 4 are used with a mildly flammable hydrofluorocarbon refrigerant in
Cotnp.
Example 4
6
5 a refrigerating machine, flame-retarding is enabled.
Reference Signs List
Comp.
Example 5
8
[0066] l...refrigerant compressor, 2...gas cooler, 3...expansion
Comp.
Example 6
10
tnechanism, 4...evaporator, 5...passage, 10. ..r efrigerating machine.

CLATMS
1. A refrigerating machine oil comprising a polyalkylene glycol
represented by the following foimula (I):
R~-(OR~),-OR~ (1)
5 [R' and R2 may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having fiom 1 to 5 carbon
atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents '
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
10 polyalkylene glycol represented by the formula (1) is fsom 1000 to
25001
the polyalkylene glycol having a ratio of a weight average
molecular weight Mw to the number average molecular weight Mn,
Mw/Mn, of from 1 .OO to 1.15,
15 the refrigerating machine oil being used with a mildly
flammable 1~ydsofluorocarbonre frigerant.
2. The refrigerating machine oil according to claim 1, wherein a
ratio of an ethylene group in the alkylene groups represented by R~ in
the polyalkylene glycol represented by the folmula (1) is 40 mol% or
20 less.
3. A working fluid composition for a refrigerating machine,
comprising:
the refrigerating machine oil according to claim 1 or 2; and
a mildly flammable hydrofluorocarbon refrigerant.
25 4. The working fluid composition for a refrigerating machine
according to claim 3, wherein the mildly flammable hydrofluorocarbon
refrigerant comprises at least one selected from the group consisting of
1,3,3,3-tetrafluoropropene and 2,3,3,3-tetrafluoropropcne.
5. Use of a composition for a refrigerating machine oil or a
working fluid composition for a refrigerating machine, the composition
5 comprising a polyalkylene glycol represented by the following formula
(1):
R'-(OR~),-OR~ (I)
[R' and R2 may be the same or different from each other and each
represent a hydrogen atom, an akyl group having from 1 to 5 cabon
10 atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
-
polyalkylene glycol represented by the formula (1) is from 1000 to
25001
the polyalkylene glycol having a ratio of a weight average
molecular weight Mw to the number average molecular weight Mn,
Mwm, of from 1.00 to 1.15,
the refrigerating machine oil being used with a mildly
flammable hydrofluorocarbon refrigerant,
20 the working fluid composition comprising a mildly flammable
hydrofluorocarbon refrigerant.
6. Use of a polyallcylene glycol for manufacturing a refrigerating
machine oil or a working fluid composition for a refrigerating machine,
the polyalkylene glycol being represented by the following formula (1):
25 R'-(OR~),-OR~ (1)
[R' and R' may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having from 1 to 5 carbon
atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents
an alkylene group having from 2 to 4 carbon atoms, n represents an
integer such that a number average molecular weight of the
5 polyalkylene glycol represented by the formula (1) is from 1000 to
25001
the polyalkylene glycol having a ratio of a weight average
molecular weight Mw to the number average molecular weight Mn,
MwlRln, of from 1.00 to 1.15,
10 the refrigerating machine oil being used with a mildly
flammable hydrofluorocarbon refrigerant,
the working fluid composition comprising a mildly flammable
hydrofluorocarbon refrigerant.
7. A method for flame-retarding a refrigerating machine with a
15 mildly flammable hydrofluorocarbon refrigerant, the method
comprising flame-retarding the refrigerating machine by using a
composition as a refrigerating machine oil, the composition comprising
a polyalkylene glycol represented by the foIlowing formula (1):
R'-(0R3),,-0R2 (1)
20 [R' and R' may be the same or different from each other and each
represent a hydrogen atom, an alkyl group having hom 1 to 5 carbon
atoms, or an acyl group having from 2 to 5 carbon atoms, R3 represents
an alkylene gsoup having from 2 to 4 carbon atoms, n represents an
integer such that a ilumbes average molecular weight of the
25 polyalkylene glycol represented by the formula (1) is from 1000 to
25001