DESCRIPTION
Title of Invention: REFRIGERATOR OK, 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 a polyvinylether for a refrigerating machine oil
or a working fluid composition for a refrigerating machine, and use of a
polyvinylether for manufacturing a refrigerating machine oil or a
10 working fluid composition for a refrigerating machine, and a method of
flame-retarding a refrigerating machine.
Background Art
[0002] CFCs (chlorofluorocarbons) and HCFCs (hydrochforofluorocarbons),
which have been conventionally used as refrigerants for
15 refrigeration equipment, have become objects of regulations due to the
problem of recent ozone layer depletion, and HFCs
(hydrofluorocarbons) are used as refrigerants instead of them.
[0003] In the case of wing a CFC or HCFC as a refrigerant,
hydrocarbon oils such as mineral oil and alkylbenzenes have been used
20 suitably as a refrigerating machine oil. However, depending on the
type of the coexistent reftigerant, the refrigerating machine oil may
exhibit unpredictable behavior in, for example, compatibility with the
re&gerant, lubricity, solution viscosity with the refrigerant, and thermal
and chemical stability, and therefore the refrigerating machine oil needs
25 to be developed for each refrigerant. Thus, as refrigerating machine
oils for an HFC reeigerant, for example, a refrigerating machine oil
containing polyalkylene glycol (see Patent Literature I), ester (see
Patent Literature 2), carbonic acid ester (see Patent Literature 3), or
polyvinylether (see Patent Literature 4) have been developed.
Citation List
5 Patent Literature
[0004] Patent Literature 1 : Japanese unexamined Patent Publication No.
H02-242888
Patent Literature 2: Japanese unexamined Patent Publication No.
H03-200895
10 Patent Literature 3: Japanese unexamined Patent Publication No.
H03-217495
Patent Literature 4: Japanese unexamined Patent Publication No.
H06-128578
Summary of Invention
15 Technical Problem
[0005] It is an object of the present invention to provide a refrigerating
machine oil of which safety has been enhanced from the viewpoint of
flame retardancy and a working fluid composition for a refrigerating
machine containing the refrigerating machine oil.
20 Solution to Problem
[0006] To solve the above described problem, the present invention
provides a refrigerating machine oil comprising a polyvinylether having
a structural unit represented by the following formula (1):
wherein R', R ~a,n d R~ may be the same or different from each other
and each represent a hydrogen atom or a hydrocarbon group, R4
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocarbon group, R5 represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R~ may be the same or
different from each other, a number average molecular weight Mn of the
polyvinylether is 500 or more and 2000 or less, a ratio of a weight
average molecular weight Mw to a number average molecular weight
Mn, Mw/Mn, of the polyvinylether is 1.10 or more and 1.25 or less, and
the refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refrigerant.
[0007] Also, the present invention provides a working fluid
composition for a refrigerating machine, comprising: the above
refrigerating machine oil; and a mildly flammable hydrofluorocarbon
refrigerant.
[0008] In the present invention, the mildly flammable
hydrofluorocarbon refrigerant may contain at least one selected from the
group consisting of difluoromethane, 1,3,3,3-tetrafluoropropene, and
2,3,3,3-tetrafluoropropene.
[0009] It may also be said that the present invention is use of a
composition for a refrigerating machine oil or a working fluid
composition for a refrigerating machine, the composition comprising a
polyvinylether having a structural unit represented by the following
formula (1):
5 wherein R', R', and R3 may be the same or different from each other
and each represent a hydrogen atom or a hydrocarbon group, R~
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocarbon group, R5 represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
10 case where m is 2 or more, a plurality of R~ may be the same or
different from each other, a number average molecular weight Mn of the
polyvinylether is 500 or more and 2000 or less, a ratio of a weight
average molecular weight Mw to a number average molecular weight
Mn, M w h , of the polyvinylether is 1.10 or more and 1.25 or less, the
15 refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refrigerant, and the working fluid composition for a
refrigerating machine comprises the refrigerating machine oil and the
mildly flammable hydrofluorocarbon refrigerant.
[0010] Also, it may also be said that the present invention is use of a
20 composition for manufacturing a refrigerating machine oil or a working
fluid composition for a rekigerating machine, the colnposition
comprising a polyvinylether having a structural unit represented by a
following formula (1):
wherein R', R', and R3 may be the same or different &om each other
and each represent a hydrogen atom or a hydrocarbon group, R~
represents a divalent hydrocarbon group or an ethereal
5 oxygen-containing divalent hydrocarbon group, R' represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R4 may be the same or
different from each other, a number average molecular weight Mn of the
polyvinylelher is 500 or more and 2000 or less, a ratio of a weight
10 average molecular weight Mw to the number average molecular weight
Mn, M w k , of the polyvinylether is 1.10 or more and 1.25 or less, the
refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refrigerant, and the working fluid composition for a
refrigerating machine comprises the refigerating machine oil and the
15 mildly flammable hydrofluorocarbon refrigerant.
[0011] The present invention also provides a method of flame-retarding
a refrigerating machine in which a mildly flammable hydrofluorocarbon
I
8 refrigerant is used, the method comprising using, as a refrigerating
i
k
t machine oil, a composition comprising a polyvinylether having a
::
9
d
A :, l 20 structural unit represented by a following formula (1):
wherein R', R2, and R3 may be the same or different from each other
and each represent a hydrogen atom or a hydrocarbon group, R4
represents a divalent hydrocarbon group or an ethereal
5 oxygen-containing divalent hydrocarbon group, R' represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R4 may be the same or
different from each other, a number average molecular weight Mn of the
polyvinylether is 500 or more and 2000 or less, and a ratio of a weight
10 average molecular weight Mw to the number average molecular weight
Mu, Mwfw of the polyvinylether is 1.10 or more and 1.25 or less.
Advantageous Effects of Invention
[0012] According to the present .invention, it becomes possible to
provide a rehigerating machine oil of which safety has been enhanced
15 from the viewpoint of flame retardancy and a working fluid composition
for refrigerating machines containing the refrigerating machine oil.
Brief Description of Drawings
[0013] Figure 11 Figure 1 is a schematic view showing an example of
the configuration of a refrigerating machine.
20 Description of Embodiments
[0014] Hereinbelow, preferred embodiments of the present invention
will be described in detail.
[0015] A refrigerating machine oil according to the present embodiment
comprises a polyvinylether which has a structural unit represented by
the following formula (1):
wherein R', R2, and R~ may be the same or different from each other
5 and each represent a hydrogen atom or a hydrocarbon group, R~
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocarbon group, R' represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R~ may be the same or
10 different .from each other, the number average molecular weight Mn of
the polyvinylether being 500 or more and 2000 or less, and the ratio of
the weight average molecular weight Mw to the number average
molecular weight Mn, MwlMn, of the polyvinylether being 1.10 or
more and 1.25 or less. R' to R5 and m each may be the same or
15 different, depending on the structural units constituting the
polyvinylether.
[0016] The working fluid composition for refrigerating machines
according to the present embodiment contains a refrigerating machine
oil containing a polyvinylether and a mildly flammable
20 hydrofluorocarbon refrigerant, the polyvinylether having a structural
unit represented by the above formula (I), the number average
molecular weight Mn of 500 or more and 2000 or less, and the ratio of
the weight average molecular weight Mw to the number average
molecular weight Mn, Mw&, of 1.10 or more and 1.25 or less. The
working fluid composition for refrigerating machines according to the
present embodiment encompasses a composition comprising a
refi-igerating machine oil according to the present embodiment and a
5 mildly flakable hydrofluorocarboll refrigerant.
, [0017] The number of carbon atoms of the hydrocarbon groups
represented by R1, R2, and R~ in the formula (1) is preferably 1 or more,
more preferably 2 or more, still more preferably 3 or more, and
preferably 8 or less, more preferably 7 or less, still more preferably 6 or
10 less. It is preferred that at least one of R', R2, and R' in the formula (1)
be a hydrogen atom, and it is more preferred that the all be hydrogen
atoms.
[0018] The number of carbon atoms of the divalent hydrocarbon group
or the ethereal oxygen-containing divalent hydrocarbon group
15 represented by R~ in the formula (1) is preferably 1 or more, more
preferably 2 or more, still more preferably 3 or more, and preferably 10
or less, more preferably 8 or less, still more preferably 6 or less. The
ethereal oxyge~i-containingd ivalent hydrocarbon group represented by
R4 in the formula (1) may be, for example, a hydrocarbon group having
20 oxygen atom forming an ether bond in the side chain.
[0019] It is preferred that R~ in the formula (1) be a hydrocarbon group
having 1 to 20 carbon atoms. Examples of this hydrocarbon group
include alkyl groups, cycloalkyl groups, phenyl groups, aryl groups, and
arylalkyl groups. Of these, alkyl groups are preferred, and alkyl
25 groups having 1 to 5 carbon atoms are more preferred.
[0020] m in the formula (1) is preferably an integer of 0 or more, more
preferably an integer of 1 or more, still more preferably an integer of 2
or more, and preferably an integer of 20 or less, more preferably an
integer of 18 or less, still more preferably an integer of 16 or less. It is
prefmed that the average value of m in all the structural units
5 constituting the polyvinylether be 0 to 10.
[0021] Polyvinylether inay be a homopolymer composed of a single
structural unit selected from those represented by the formula (I), may
be a copolymer composed of two or more structural units selected kom
those represented by the formula (I), or may be a copolymer composed
10 of a structural unit represented by the formula (1) and other structural
unit. By using a copolymer as the polyvinylether, it is possible to
further improved the lubricity, insulation property, hygroscopicity and
the l i e while the compatibility with the refrigerant of the rehigerating
machine oil is satisfied. In this case, desired properties of the above
15 refrigerating machine oil can be obtained by selecting the type of the
raw material monomers, the type of the initiator, the ratio of the
structural unit in the copolymer and the like as appropriate.
Accordingly, it is possible to freely obtain a refrigerating machine oil in
conformity with demands for lubricity, compatibility, or the like which
20 vary depending upon the model of the compressor, the material quality
of the lubricating part, the rekigeration capability, the type of refrigerant
and the like in a refrigerating system or an air conditioning system.
The copolymer may be either of a block copolymer or a random
copolymer.
25 [0022] When the polyvinylether is a copolymer, it is preferred that the
copolymer contain a structural unit (1-I), which is represented by the
above formula (1) and in which R' is an alkyl group having 1 to 3
carbon atoms, and a structural unit (1-2), which is represented by the
above formula (1) and in which R~ is an alkyl group having 4 to 20
carbon atoms, preferably 4 to 10 carbon atoms, more preferably 4 to 8
5 carbon atoms. As IC5 in the structural unit (1-I), an ethyl group is
particularly preferred, and as R' in the structural unit (1-2), an isobutyl
group is particularly preferred. Additionally, when the polyvinylether
accordiig to the present embodiment is a copolymer containing the
above structural unit (1-1) and (1-Z), it is preferred that the molar ratio
10 between the structural unit (1-1) and the structural unit (1-2) be 5:95 to
95:5, it is more preferred that the molar ratio be 20:80 to 90:10, and it is
still more preferred that the molar ratio be 70:30 to 90:lO. If the molar
ratio is within the above range, it tends to be possible to further enhance
the compatibility with a refrigerant and to lower the hygroscopicity.
15 [0023] The polyvinylether according to the present embodiment may be
one composed singly of a structural unit represented by the above
formula (I), but may be a copolymer further comprising a structural unit
represented by the following formula (2). In this case, the copolymer
may be either of a block copolymer or a random copolymer.
20 [0024]
In the formula, R6 to R9 may be the same or different from each other
and each represent a hydrogen atom or a hydrocarbon group having 1 to
20 carbon atoms.
[0025] The polyvinylether can produced by polymerization of a
vinylether monomer corresponding to a structural unit represented by
the formula (I), or copolymerization of a vinylether monomer
' 5 corresponding to a structural unit represented by the formula (1) and a
hydrocarbon monomer having an olefmic double bond corresponding to
a structural unit represented by formula (2). As the vinylether
monomer corresponding to a structural unit represented by the formula
(I), monomers represented by the following formula (3) are suitable.
10 [0026]
In the formula, R', RZ, R3, R4, R5, and m each represent the same
defmition as R', R2,R ~R,4, R ~a,nd m in the formula (1).
[0027] As the polyvinylether, those having the following terminal
15 structure (A) or (B) are suitable:
[0028] (A) A structure in which one terminus is represented by the
formula (4) or (5), and the other terminus is represented by the formula
(6) or (7).
[0029]
~ 1 %~ 2 1
I I
HC-C- (4)
20
I I
R3I O ( R ~ ' O ) ~ R ~ ~
In the formula, R", RZ1, and R~~ may be the same or different from each
other and each represent a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms, R4' represents a divalent hydrocarbon group
or ethereal oxygen-containing divalent hydrocarbon group having 1 to
10 carbon atoms, R51 represents a hydrocarbon group having 1 to 20
carbon atoms, and m represents the same definition as m in the formula
5 (I), and in the case where m is 2 or more, a plurality of R41 may be the
same or different from each other.
[0030]
~ 6 1~ 7 1
I I
HC-CI
I RBI ~ 9 1
In the formula, R6', R~', R81, and Rgl may be the same or different from
10 each other and each represent a hydrogen atom or a hydrocarbon group
having 1 to 20 carbon atoms.
1003 11
In the formula, K", RZ2a?n d R~~m ay be the same or different from each
15 other. and each represent a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms, R4' represents a divalent hydrocarbon group
or ethereal oxygen-containing divalent hydrocarbon group having 1 to
10 carbon atoms, R5' represents a hydrocarbon group having 1 to 20
carbon atoms, and m represents the same definition as m in the formula
20 (I), and in the case where m is 2 or more, a plurality of R~~ may be the
same or different.
In the formula, R ~R7'~, ,Rs 2, and R" may be the same or different from
each other and each represent a hydrogen atom or a hydrocarbon group
having 1 to 20 carbon atoms.
5 [0033] (B) A structure in which one terminus is represented by the
formula (4) or (5), and the other terminus is represented by the formula
(8).
[0034]
10 In the formula, R13, R ~an~d R,~ ~m ay be the same or different horn each
0 t h and each represent a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms.
[0035] Of such polyvinylethers, polyvinylethers (a), (b), (c), (d), and (e)
listed below arc particularly preferred as the main component of the
15 refrigerating machine oil according to the present embodiment:
(a) Polyvinylethers having a structure in which one terminus is
represented by the formula (4) or (5) and the other terminus is
represented by the formula (6) or (71, wherein in the formula (1 ), R', R2,
and R3 are each a hydrogen atom, m is an integer of 0 to 4, R4 is a
20 divalent hydrocarbon group having 2 to 4 carbon atoms, and R5 i s a
hydrocarbon group having 1 to 20 carbon atoms.
(b) Polyvinylethers having only a structural unit represented by the
formula (I), in which one terminus is represented by the formula (4) and
the other terminus is represented by the Formula (6), wherein in the
formula (I), R', R' and R3 are each a hydrogen atom, m is an integer of
0 to 4, R4 is a divalent hydrocarbon group having 2 to 4 carbon atoms,
5 and R5 is hydrocarbon group having 1 to 20 carbon atoms.
(c) Polyvinylethers having a structure in which one terminus is
represented by the fonnula (4) or (5) and the other terminus is
represented by the formula (a), wherein in the formula (I), R', R2, and
R3 are each a hydrogen atom, m is an integer of 0 to 4, R4 is a divalent
10 hydrocarbon group having 2 to 4 carbon atoms, and R5 is a hydrocarbon
group having 1 to 20 carbon atoms.
(d) Polyvinylethers having only a structural unit represented by the
formula (I), in which one tenninus is represented by the formula (5) and
the other terminus is represented by the formula (8), wherein in the
15 formula (1 ), R', RZ and R3 are each a hydrogen atom, m is an integer of
0 to 4, R4 is a divalent hydrocarbon group having 2 to 4 carbon atoms,
I
and R5 is hydrocarbon group having 1 to 20 carbon atoms.
(e) Any one of the above (a), (b), (c), and (d) having a structural unit in
which R5 in the formula (I) is a hydrocarbon group having 1 to 3 carbon
20 atoms and a structural unit in which R5 in the formula (1) is a
hydrocarbon group having 4 to 20 carbon atoms.
[0036] The number average molecular weight (Mn) of the
polyvinylether is preferably 500 or more, more preferably 700 or more,
still more preferably 800 or more, particularly preferably 900 or more,
25 most preferably 1000 or more, and preferably 2000 or less, more
preferably 1900 or less, still more preferably 1500 or less. In the case
where the number average molecular weight of the polyvinylether is
500 or more, the lubricity is increased under coexistence of a mildly
flammable hydrofluorocarbon refrigerant. In the case where the
number average molecular weight of the polyvinyleiher is 2000 or less,
5 the range of the composition 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.
10 [0037] The ratio of the weight average molecular weight (Mw) to the
number average molecular weight (Mn), (MwlMn) of the polyvinylether
is preferably 1.10 or more, more preferably 1.15 or more, still more
preferably 1.16 or more, particularly preferably 1.1 7 or more, and
preferably 1.25 or less, more preferably 1.23 or less, still more
15 preferably 1.22 or less particularly preferably 1.21 or less. If Mwhh
is 1.10 or more, the range of the composition which exhibits
compatibility to the mildly flammable hydrofluorocarbon becomes
wider. Tf Mw/Mn is 1.25 or less, it is possible to suppress lubrication
defects of a refrigerant compressor and inhibition of heat exchange in an
20 evaporator. The weight average molecular weight (Mw) of the
polyvinylether is selected as appropriate such that Mn and MwlMn
satisfy the above conditions.
[0038] The weight average molecular weight (Mw), the number
average molecular weight (Mn), and the ratio of the weight average
25 molecular weight (Mw) to the number average molecular weight (Mn)
(Mw/Mn) in the present invention mean Mw, Mn, and Mw/Mn obtained
by GPC analysis (values in terms of polystyrene (standard sample)),
respectively. Mw, Mn, and MwiMn are measured as follows, for
example.
[0039] Chloroform is used as the solvent, and polyvinylether is diluted
5 to thereby prepare a solution of which sample concentration is 1% by
mass. The 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
from 100 to 10000 with a refractive index detector. It should be noted
10 that, after the relationship between the column retention time and the
molecular weight is determined by using a polystyrene standard of
which molecular weight is obvious to thereby form a calibration curve
separately, the molecular weight is determined from the obtained
retention time.
15 [0040] It is preferred that the flash point of the polyvinylether be 195°C
or more, it is more preferred that the flash point be 200°C or more, and
it is still more preferred that the flash point be 205°C or more. The
flash point in the present invention means the flash point measured in
compliance with JIS IS2265-4 "Determination of flash points - Part4:
20 Cleveland open cup method".
[0041] It is preferred that the autoignition point of the polyvinylether be
335°C or more, it is more preferred that the autoignition point is 340°C
or more, and it is still more preferred that the autoignition point is
345°C or more. The autoignition point in the present invention means
25 an autoignition point measured in compliance with ASTM E659-1978.
[0042] The kinematic viscosity of the polyvinylether at 100°C is
preferably 6.5 mm2/s or more, more preferably 7.0 &/s or more, still
more preferably 7.5 mm2/s or more, and preferably 9.5 mm2/s or less,
more preferably 9.0 mm2/s or less, still more preferably 8.5 mm2/s or
less. If the kinematic viscosity at 100°C is the lower limit
5 above-mentioned or more, the lubricity is increased under coexistence
of a refrigerant. If the kinematic viscosity at 100°C is the lower limit
above-mentioned or less, the range of the composition which exhibits
compatibility to the refrigerant becomes wider and it is possible to
suppress poor lubrication of a refrigerant compressor and inhibition of
10 heat exchange in an evaporator.
[0043] The kinematic viscosity of the polyvinylether at 40°C is
preferably 50 mm2/s or more, more preferably 55 mm2/s or more, still
more preferably 60 m&/s or more, and preferably 80 mm2/s or less,
more preferably 75 mm2/s or less, still more preferably 70 &/s or
15 less. If the kinematic viscosity at 40°C is the lower limit
above-mentioned or more, the lubricity and the sealability of the
compressor tend to increase. If the kinematic viscosity at 40°C is the
lower limit above-mentioned or less, the range of the composition
which exhibits compatibility to the refrigerant under low temperature
20 conditions becomes wider and it is possible to suppress poor lubrication
of a refrigerant compressor and inhibition of heat exchange in an
evaporator.
[0044] The viscosity index of the polyvinylether is preferably 50 or
more, more preferably 60 or more, still more preferably 70 or more, and
25 preferably 120 or less, more preferably 100 or less, still more preferably
80 or less. If the viscosity index is the lower limit above-mentioned or
more, the lubricity of the refrigerating machine oil on sliding portions is
maintained. If the viscosity index is the upper limit above-mentioned
or less, energy loss caused by the resistance between the refi-igerating
machine oil at a high temperature and the piping becomes smaller.
5 [0045] The kinematic viscosity and viscosity index in the present
invention means the kinematic viscosity specified in JIS K2283-1993.
[0046] The pour point of the polyvinylether is preferably -10°C or less,
more preferably -20°C or less, and preferably -50°C or more. If a
polyvinylether of which the pour point is -10°C or less is used, it tends
10 to prevent the refrigerating machine oil in a refrigerant circulation
system from s o l i d i i g at low temperatures. The pour point in the
present invention means the pour point specified in JIS K2269.
100471 Polyvinylethers can be produced by radical polymerization,
cation polymerization, radiation polymerization or the like of the
15 aforementioned monomers. By providing a routine
separation~purification process after the polymerization reaction is
finished, the intended polyvinylether having the structural unit
represented by the formula (1) can be obtained.
[0048] In the production step of the polyvinylether, there is a case
20 where a side reaction is caused to thereby form an unsaturated group
such as an aryl group in the molecule. From the viewpoints of
increases in the thermal stability of the polyvinylether itself, inhibition
of formation of sludge caused by formation of a polymerized product,
and inhibition of formation of a peroxide due to decreases in the
25 anti-oxidative property (oxidation prevention property), it is prefened to
use a polyvinylether having a low degree of unsaturation due to an
unsaturated group and the like as the polyvinylether. It is preferred
that the degree of unsaturation of the polyvinylether be 0.04 meqlg or
less, it is more preferred that the degree of unsaturation be 0.03 meqlg
or less, and it is still more preferred that the degree of unsaturation be
5 0.02 meqlg or less. It is preferred that the peroxide value of the
polyvinylether be 10.0 meqkg or less, it is more preferred that the
peroxide value be 5.0 meqflcg or less, and it is still more preferred that
the peroxide value be 1.0 meqkg. It is preferred that the carbonyl
value of the polyvinylether be 100 ppm by weight or less, it is more
10 preferred that the carbonyl value be 50 ppm by weight or less, and it is
further preferred that the carbonyl value be 20 ppm by weight or less.
It is preferred that the hydroxy value of the polyvinylether be 10
mgKOWg or less, it is more preferred that the hydroxy value be 5
mgKOWg or less, and it is still more preferred that the hydroxy value
15 be 3 mgKOWg or less.
LO0491 The degree of unsaturation, peroxide value and carbonyl value
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
20 unsaturation in the present invention is a value (meqlg) obtained by
reacting a Wijs sol~~tio(InC 1-acetic acid solution) with a sample, leaving
the reaction mixture to stand in a dark place, subsequently reducing the
excess IC1 to iodine, titrating the iodine portion with sodium thiosulfate
to calculate the iodine value, and then converting the iodine value to
25 vinyl equivalents (meqlg). The peroxide value in the present invention
is a value (meqkg) obtained by adding potassium iodide to a sample,
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 prese2t invention is a value (ppm
by weight) obtained by allowing 2,4-dinitrophenylhydrazine to act on a
5 sample to produce colorable quinoid ions, measuring the absorbance of
the sample at 480 nm, and converting it to a carbonyl content based on a
predetermined calibration curve with cinnamaldehyde as the standard
substance. The hydroxy value in the present invention means the
hydroxy value measured in compliance with JIS K0070:1992.
10 [005O] Although a refrigerating machine oil can increase the safety for
the refrigerating machine oil and a working fluid composition for
refrigerating machines containing the refrigerating machine oil fi-om the
viewpoint of flame retardancy even in the case where the refrigerating
machine oil contains only the above polyvinylether, the refrigerating
15 machine oil may contain a base oil described below other than the above
polyvinylether and additives as required.
[0051] The content of the above described polyvinylether in the
refrigerating machine oil is not particularly limited provided that the
above described excellent properties are not impaired, but, based on the
20 total amourit of the refrigerating machine oil, it is preferred the content
be 50% by mass or more, it is more preferred that the content be 70% by
mass or more, it is still more preferred that the content be 80% by mass
or more, and it is particularly preferred that the content be 90% by mass
or more. If the content of the above described polyvinylether is 50%
25 by mass or more, it is possible to further increase the safety of the
refrigerating machine oil and the working fluid composition for
rekigerating machines containing the refrigerating machine oil.
[0052] As a base oil other than the above described polyvinylether, it is
possible to use hydrocarbon oils, such as mineral oils, olefin polymers,
naphthalene compounds, and alkylbenzenes, and ester base oils (such as
5 monoesters, diesters, and polyol esters), and synthetic oils composed of
a compound having oxygen atoms such as polyalkylene glycols,
polyvinylethers other than the above described polyvinylethers, ketones,
polyphenyl ethers, silicones, polysiloxanes and perfluoroethers. As the
synthetic oil composed of a compound having oxygen atom, polyol
10 esters and polyalkylene glycols are preferably used.
[0053] The refrigerating machime oil and the working fluid composition
for refrigerating machines of the present embodiment can comprise
conventionally-known additives for refrigerating machine oil as
required, in order to further 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, but it is preferably
10% by mass or less and hrther preferably 5% by mass or less, based
on the total amount of the refrigerating machine oil.
[0054] The kinematic viscosity of the refrigerating machine oil at 40°C
is not particularly limited, but is preferably 3 d l s or more, more
25 preferably 4 d s or more, still more preferably 5 rn&s or more, and
preferably 1000 mm2/s or less, more preferably 500 mm2/s or less, still
more preferably 400 mm2/s or less. The kinematic viscosity of the
refrigerating machine oil at 100°C is not particularly limited, but is
preferably 1 mm2/s or more, more preferably 2 mm2/s or more, still
more preferably 3 d s or more, and preferably 100 mm2/s or less,
5 more preferably 50 rnm2/s or less, still more preferably 30 rnrn2/s or
less.
[0055] The moistwe content of the refrigerating machine oil is not
particularly limited, but it is preferably 500 ppm or less, further
preferably 300 ppm or less, and more preferably 200 ppm or less, based
10 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 be low, from the viewpoint of the
inauence on the~mal/chemical stabiity and the electrical insulation
property of the refrigerating machine oil.
15 [0056] The acid value of the refrigerating machme oil is not particularly
limited, but it is preferably 0.1 mgKOH1g or less and fiuther preferably
0.05 mgKOH/g or less, in order to prevent corrosion of the metal used
in a refrigerating machine or piping, and to prevent degradation of the
ester contained in the reeigerating machine oil of the present
20 embodiment. The acid value in the present invention means the acid
value measured in compliance with JIS K2501 "Petroleum Products
And Lubricating Oils-Neutralization Value Test Method".
COO571 The ash content of the refrigerating machine oil is not
particularly limited, but it is preferably 100 ppm or less and firther
25 preferably 50 ppm or less, in order to increase the thermal/chemical
stability of the refrigerating machine oil and to suppress the occurrence
of sludge or the like. The ash content in the present invention means
the ash content measured in compliance with JIS K2272 "Crude
oil/petroleum product ash content and sulfated ash content test method".
[0058] The refrigerating machine oil is used with a mildly flammable
5 hydrofluorocarbon (HFC) refrigerant. The working fluid composition
for refrigerating machines contains a mildly flammable
hydrofluorocarbon (HFC) refrigerant. In the hydrofluorocarbon (HFC)
refrigerants, saturated fluorinated hydrocarbon refrigerants (also
referred to as hydrofluoroalkane refrigerants) and unsaturated
10 fluorinated hydrocarbon refrigerants (also referred to as
hydrofluoroalkene refrigerants, hydrofluoroolefin refrigerants, or HFO
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
15 of Heating, Refrigerating and Air-conditioning Engineers).
[0059] Examples of the mildly flammable hydrofluorocarbon
refrigerant include difluoromethane (HFC-32),
1,3,3,3-tetrafluoropropene (IFC-l234ze), and
2,3,3,3-tetrafluoropropene (I-niC-1234yf). As the mildly flammable
20 hydrofluorocarbon refrigerant, 1,3,3,3-tetrafluoropropene
QIFC-1234ze) or 2,3,3,3-tetrafluoropropene (FIFC-1234yf) is preferred.
[0060] The refrigerant used with the refrigerating machine oil may be a
mixed refrigerant of a mildly flammable hydrofluorocarbon refrigerant
and other refrigerant. Examples of other refrigerants include
25 hydrofluorocarbon refrigerants other than mildly flammable
hydrofluorocarbon refrigerants, fluorine-containing ether-based
I
I
I refrigerants such as perfluoroethers, bis(trifluoromethy1)sulfide I reEigerants, trifluoromethyl iodide refrigerants, and natural refrigerant,
such as dimethylether, carbon dioxide, ammonia, and hydrocarbons.
As other refrigerants, refrigerants composed of a compound which does
5 not have an oxygen atom are preferably used.
[0061] Examples of hydrofluorocarbon refrigerant other than the mildly
flammable hydrofluorocarbon refrigerant include trifluoromethane
(WC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane
PC-134), 1,1,1,2-tetrafluoroethane (FFC-l34a), l,l,l-trifluoroethane
10 (EIFC- 143a), 1,l-difluoroethane (WC-l52a), fluoroethane (I-WC-16 I),
1,1,1,2,3,3,3-heptafluoropropane (WC-227ea), 1,1,1,2,3,3-
hexafluoropropane @FC-236ea), 1,1,1,3,3,3 -hexafluoropropane
(HFC-236fa), 1,1,1,3,3-pentafluoropropane (J3FC-245fa), l,l, 1,3,3-
pentafluorobutane (I-IFC-365mfc), and 1,2,3,3,3-pentafluoropropene
15 @FC-1225ye).
[0062] As the hydrocarbon refigerant, hydrocarbons having 3 to 5
carbon atoms are preferred, and specifically, examples include methane,
ethylene, ethane, propylene, propane, cyclopropane, normal butane,
isobutane, cyclobutane, methylcyclopropane, 2-methylbutane, normal
20 pentane, or mixtures of two or more of these. Of these, those which
are gaseous at 25'C and 1 atmosphere are preferably used, and propane,
normal butane, isobutane, 2-methylbutane or a mixture of these is
preferred.
[0063] Examples of the fluorine-containing ether-based refiigerant
25 specifically include WE-134p, I-FE-245mc, HFE-236mf, WE-236me,
HFE-338mcf, HFE-365mcf, J3FEU245mf, WE-347mmy, WE-347mcc,
HFE-125, WE-143m, EIFE-l34m, and WE-227me, and these
refrigerants are selected as appropriate depending on uses and required
performance.
[0064] In the case where the refrigerant is a mixed refrigerant, it is
5 preferred that the mixing ratio between the mildly flammable
hydrofluorocarbon refrigerant and other refrigerant (mass ratio, mildly
flammable hydrofluorocarbon refrigerant:other refrigerant) be 1:99 to
99:1, and it is more preferred that the mixing ratio be 5:95 to 955.
[0065] The refrigerating machine oil is, usually in a refrigerating or air
10 conditioning apparatus, mixed with a single mildly flammable
hydrofluorocarbon refrigerant or a mixed refrigerant and present as a
component of a working fluid composition for reeigerating machines.
The content of the refkigeration oil in the working fluid composition for
refrigerating machines is preferably 1 part by mass or more, more
15 preferably 2 parts by mass or more, and preferably 500 parts by mass or
less, more preferably 400 parts by mass or less, based on 100 parts by
mass of the reiligerant.
[0066] The refrigerating machine oil and the working fluid composition
for refrigerating machines are preferably used in air conditioners or
20 refrigerating machines having a reciprocating or rotating closed
compressor, or in open or closed automobile air conditioners. The
refrigeration oil and the working fluid composition for a refrigerating
machine are preferably used in dehumidifiers, hot water suppliers,
cooling apparatuses, such as freezers, fi-eezing-refrigerating warehouses,
25 vending machines, showcases, and chemical plants. The refrigeration
oil and the working fluid composition for a refrigerating machine are
also preferably used in those having a centrifugal compressor.
[0067] Figure 1 is a schematic view showing an example of the
configuration of the refrigerating machine described above. As shown
in Figure 1, a refrigerating machine 10 comprises a refrigerant
5 circulation system in which at least a compressor 1, a condenser 2, an
expansion mechanism 4, and an evaporator 5 are successively connected
by a passage 6. The refrigerant circulation system may further
comprise a desiccator 3.
[0068] In the compressor 1, a small amount of the mildly flammable
10 hydrofluorocarbon refrigerant (hereinbelow, also simply referred to as
"refrigerant") and a large amount of the rehigaating machine oil coexist
under a high temperature (usually 70 to 120°C) condition. The
refrigerant released from the compressor 1 to the passage 6 is gaseous
and contains a small amount of (usually 1 to 10%) the refrigerating
15 machtne oil in the form of a mist. In this refrigerating machine oil
mist, a small amount of the refrigerant is dissolved (point a in Figure 1).
Next, in the condenser 2, the gaseous refrigerant is compressed to be a
high-density fluid, and under a relatively high temperature (usually 50
to around 70°C) condition, a large amount of the refrigerant and a small
20 amount of the refrigerating machine oil coexist (point b in Figure I).
Furthermore, the mixture of a large amount of the refrigerant and a
small amount of the refrigerating machine oil is successively supplied to
the desiccator 3, the expansion mechanism 4, and the evaporator 5 to
rapidly have a lower temperature (usually -40 to 0°C) (points c and d in
25 Figure 1) and be returned back to the refrigerant compressor 1.
[0069] By using the polyvinylether of the present embodiment as the
refrigerating machine oil, it becomes possible to flame-retard the
refrigerating machines in which a mildly flammable hydrofluorocarbon
refrigerant as mentioned zbove is used.
Examples
5 [0070] Hereinbelow, the present invention will be described more
specifically based on examples and comparative examples, but the
present invention is not limited in any way by the examples below.
[0071] [Examples 1 to 5 and Comparative Examples 1 to 51
In Examples 1 to 5 and Comparative Examples 1 to 5, base oils
10 1 to 10 shown below were each used to prepare a refrigerating machine
oil.
[0072] @ase oil)
Base oil 1 :
Copolymer of ethylvinylether and isobutylvinylether [ethylvinylether /
15 isobutylvinylether = 812 (molar ratio), number average molecular
weight (Mn): 500, ratio of the weight average molecular weight (Mw) to
the number average molecular weight (Mn) (MwIMn): 1.25, kinematic
viscosity at 40°C: 50.2 n~rn~lksi,n ematic viscosity at 100°C: 6.90
mm2/s, viscosity index: 911
20 Base oil 2:
Copolymer of ethylvinylether and isobutylvinylether [ethylvinylether /
isobutylvinylether = 911 (molar ratio), number average molecular
weight (Mn): 1200, ratio of the weight average molecular weight (Mw)
to the number average molecular weight (h4n) (MwMn): 1.23,
25 kinematic viscosity at 40°C: 67.8 &Is, kinematic viscosity at 100°C:
8.20 mm2/s, viscosity index: 861
Base oil 3:
Ethylvinylether polymer [number average molecular weight (Mn): 700,
ratio of the weight average molecular weight (Mw) to the number
average molecular weight (Mn) (MwIMn): 1.22, kinematic viscosity at
5 40°C: 50.4 mm2/s, kinematic viscosity at 100°C: 6.81 mm2/s, viscosity
index: 861
Base oil 4:
Ethylvinylether polymer [number average molecular weight (Mn):
1300, ratio of the weight average molecular weight (Mw) to the number
10 average molecular weight (Mn) (MwIMn): 1.20, kinematic viscosity at
40°C: 62.5 d s , kinematic viscosity at 100°C: 7.91 mm2/s, viscosity
index: 901
Base oil 5:
Copolymer of a methylvinylether and ethylvinylether [methylvinylether
15 / ethylvinylether = 119 (molar ratio), number average molecular weight
(Mu): 2000, ratio of the weight average molecular weight (Mw) to the
number average molecular weight (Mn) (MwIMn): 1.19, kinematic
viscosity at 40°C: 72.6 mm2/s, kinematic viscosity at 100°C: 8.46
mm2/s, viscosity index: 831
20 Base oil 6:
Copolymer of ethylvinylether and isobutylvinylether [ethylvinylether /
isobutylvinylether -; 812 (molar ratio), number average molecular
weight (Mn): 400, ratio of the weight average molecular weight (Mw) to
the number average molecular weight (Mn) (Mw/Mn): 1.23, kinematic
25 viscosity at 40°C: 42.3 mm2/s, kinematic viscosity at 100°C: 6.18
rnm2/s, viscosity index: 891
Base oil 7:
Copolymer of ethylvinylether and isobutylvinylether [ethylvinylether I
isobutylvinylether = 911 (molar ratio), number average moleculir
weight (Mn): 400, ratio of the weight average molecular weight (Mw) to
' 5 the number average molecular weight @In) (Mw/Mn): 1.26, kinematic
viscosity at 40°C: 62.1 mm2/s, kinematic viscosity at 100°C: 7.99
d s , viscosity index: 931
Base oil 8:
Ethylvinylether polymer [number average molecular weight (Mn):
10 1000, ratio of the weight average molecular weight (Mw) to the number
average molecular weight (Mn) (MwIMn): 1.27, kinematic viscosity at
40°C: 55.7 mm2/s, kiiematic viscosity at 100°C: 7.35 d / s , viscosity
index: 901
Base oil 9:
15 Ethylvinylether polymer [number average molecular weight (Mn):
1900, ratio of the weight average molecular weight (Mw) to the number
average molecular weight (Mn) (MwIMn): 1.29, kinematic viscosity at
40°C: 71.0 mm2/s, kinematic viscosity at 100°C: 8.55 mm2/s, viscosity
index: 891
20 Base oil 10:
Copolymer of a methylvinylether and ethylvinylether [methylvinylether
/ ethylvinylether = 119 (molar ratio), number average molecular weight
(Mn): 2200, ratio of the weight average molecular weight (Mw) to the
number average molecular weight (Mn) (Mw/Mn): 1.3 1, kinematic
25 viscosity at 40°C: 75.9 mm2/s, kinematic viscosity at 100°C: 9.10
mm2/s, viscosity index: 931
100731 Next, on each refrigerating machine oil of Examples 1 to 5 and
Comparative Examples 1 to 5, evaluations shown below were
performed. Tlie properties of the base oils used and the results
obtained are shown together in Tables 1 and 2. It should be noted that,
5 in the tables, "ratio of methyl", "ratio of ethyl", and "ratio of butyl"
represent the content of a constituting unit of which R5 is a methyl
group, the content of a constituting unit of which R~ is an ethyl group,
and the content of a constituting unit of which R5 is a butyl group,
respectively, in the above described formula (1) (content in the
10 polyvinylether) .
[0074] (Evaluation of various properties)
Various properties of the refrigerating machine oils were
evaluated in compliance with test methods shown below.
Kinematic viscosity: JIS K2283-1993
15 Pour point: JIS K2269
Flash point: JIS K2265-4
Autoignition point: ASTM E659-1978
[0075] (Refrigerant compatibility evaluation)
In compliance with JIS-K-2211, "Refrigerating machine oils",
20 "Refrigerant compatibility test method", 10 g of the refrigerating
machine oil was added to 10 g of difluoromethane (R32),
2,3,3,3 -tetrafluoropropene @FC- 1234yf), or 1,3,3,3-tetrafluoropropene
(HFC-1234ze) to observe whether the refrigerant and the refrigerating
machime oil were dissolved in each other at 0°C. In the tables,
25 "compatible1' 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.
100761 [Table I]
Compatibility 1 Compatible I Compatible / Compatible 1 Compatible I Compafible
Refrigerant / HFC-1234vf I HFC-1234vf I HFC-1234vf I HFC-1234vf / HFC-1234vf t
Kinematic
viscosiv
[mm2ls]
40°C
looDc
-
Compatibility
RefEgerant
Compatibility
Flash ~oinltD Cl
Pour point ["C]
Refrkerant
50.2
6.90
<-45
R32
Compatible
HFC-1234ze
Compatible
201
67.8
8.20
Compatible
HFC-1234ze
Compatible
206
Compatible
HE%-1234ze
Compatible
212
G45
R32
50.4
6.81
,
Compatible
HFC-1234~
Compatible
214
1-45
R32
3-
Compatl%le
HFC-1234ze
Compatible
21 9
62.5
7.91
72.6
8.46
C45
R32
<-45
R32
[0077] [Table 21
I Flash ~oinft"C 1 1 181 / 191 1 178 1 186 1 185 /
viscosity
[ m d s ] 100°C
Pour point PC]
Refrigerant
mechanism, 5.. .evaporator, 6.. .passage, 10.. .refrigerating machine.
7.99
C45
R32
6.18
~ 4 5
R32
Autoignition point YCl 314
7.35
<-45
R32
Reference Signs List
322
8.55
4 5
R32
319
9.10
<-45
R32
328 33 1

CLAIMS
1. A refrigerating machine oil comprising a polyvinylether having
a structural unit represented by the following formula (1):
5 wherein R', R ~a,n d R3 may be the same or different from each
other and each represent a hydrogen atom or a hydrocarbon group, R'
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocarbon group, R5 represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
10 case where m is 2 or more, a plurality of R4 may be the same or
different from each other,
a number average molecular weight Mn of the polyvinylether is
500 or more and 2000 or less,
a ratio of a weight average molecular weight Mw to a number
15 average molecular weight Mn, Mw/Mn, of the polyvinylether is 1.10 or
more and 1.25 or less, and
the refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refrigerant.
2. A working fluid composition for a refrigerating machine,
20 comprising:
the refrigerating machine oil according to claim 1; and
a mildly flammable hydrofluorocarbon refrigerant.
3. The working fluid composition for a refrigerating machine
according to claim 2, wherein the mildly flammable hydrofluorocarbon
refrigerant comprises at least one selected from difluoromethane,
1,3,3,3-tetrafluoropropene,a nd 2,3,3,3-tetrafluoropropene.
4. Use of a composition for a refrigerating machine oil or a
5 working fluid composition for a refrigerating machine, the composition
comprising a polyvinylether having a structural unit represented by the
following formula (1):
wherein R', R2, and R~ may be the same or different from each
10 other and each represent a hydrogen atom or a hydrocarbon group, R~
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocabon group, R5 represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R4 may be the same or
15 different from cach other,
a number average molecular weight Mn of the polyvinylether is
500 or more and 2000 or less,
a ratio of a weight average molecular weight Mw to a number
average molecular weight Mn, Mw&, of the polyvinylether is 1.10 or
20 more and 1.25 or less,
the refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refrigerant, and
the worlcing fluid composition for a refrigerating machine
comprises the refrigerating machine oil and the mildly flammable
hydrofluorocarbon refrigerant.
5. Use of a composition for manufacturing a refrigerating machine
oil or a working fluid composition for a refkigerating machine, the
composition comprising a polyvinylether having a structural unit
represented by a following formula (1):
wherein R', R2, and R~ may be the same or diffaent from each
other and each represent a hydrogen atom or a hydrocarbon group, R~
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocarbon group, R' represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R~ may be the same or
different from each other,
a number average molecular weight Mn of the polyvinylether is
500 or more and 2000 or less,
a ratio of a weight average molecular weight Mw to the number
average molecular weight Mn, MwIMn, of the polyvinylether is 1 .I0 or
more and 1.25 or less,
the refrigerating machine oil is used with a mildly flammable
hydrofluorocarbon refrigerant, and
the working fluid composition for a refrigerating machine
comprises the refrigerating machine oil and the mildly flammable
hydrofluorocarbon refrigerant.
6. A method of flame-retarding a refrigerating machine in which a
mildly flammable hydrofluorocarbon refrigerant is used, the method
comprising using, as a refrigerating machine oil, a composition
5 - comprising a polyvinylether having a structural unit represented by a
following formula (1):
wherein R*, R', and R~ may be the same or diffaent from each
other and each represent a hydrogen atom or a hydrocarbon group, R~
represents a divalent hydrocarbon group or an ethereal
oxygen-containing divalent hydrocarbon group, R5 represents a
hydrocarbon group, m represents an integer of 0 or more, and in the
case where m is 2 or more, a plurality of R~ may be the same or
different from each other,
a nusber average molecular weight Mn of the polyvinylether is
500 or more and 2000 or less, and -,
a ratio of a weight average molecular weight Mw to the number
average molecular weight Mn, MwtMn, of the polyvinylether is 1.10 or
more and 1.25 or less.