U.S. patent application number 16/320803 was filed with the patent office on 2019-05-30 for refrigerating machine oil.
This patent application is currently assigned to JXTG NIPPON OIL & ENERGY CORPORATION. The applicant listed for this patent is JXTG NIPPON OIL & ENERGY CORPORATION. Invention is credited to Yuya MIZUTANI, Hidetoshi OGATA, Yohei SHONO, Akira TADA, Kentaro YAMAGUCHI.
Application Number | 20190161701 16/320803 |
Document ID | / |
Family ID | 61017439 |
Filed Date | 2019-05-30 |
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United States Patent
Application |
20190161701 |
Kind Code |
A1 |
SHONO; Yohei ; et
al. |
May 30, 2019 |
REFRIGERATING MACHINE OIL
Abstract
The present invention provides a refrigerating machine oil
including a lubricating base oil and a compound represented by the
following formula (A): ##STR00001## wherein R.sup.a and R.sup.b
each independently represent a monovalent hydrocarbon group,
R.sup.c represents a divalent hydrocarbon group, X represents a
polar group, and Z.sup.a and Z.sup.b each independently represent
oxygen atom or sulfur atom.
Inventors: |
SHONO; Yohei; (Tokyo,
JP) ; MIZUTANI; Yuya; (Tokyo, JP) ; YAMAGUCHI;
Kentaro; (Tokyo, JP) ; TADA; Akira; (Tokyo,
JP) ; OGATA; Hidetoshi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JXTG NIPPON OIL & ENERGY CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
JXTG NIPPON OIL & ENERGY
CORPORATION
Tokyo
JP
|
Family ID: |
61017439 |
Appl. No.: |
16/320803 |
Filed: |
July 28, 2017 |
PCT Filed: |
July 28, 2017 |
PCT NO: |
PCT/JP2017/027449 |
371 Date: |
January 25, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 129/18 20130101;
C10M 2209/1085 20130101; C10M 137/04 20130101; C10M 2207/042
20130101; C10M 2207/2805 20130101; C10M 171/008 20130101; C10M
2223/041 20130101; C10M 2209/1013 20130101; C10M 2207/301 20130101;
C10M 2207/0406 20130101; C10N 2030/06 20130101; C10N 2040/30
20130101; C10M 137/02 20130101; C10N 2020/101 20200501; C10M 169/04
20130101; C10M 105/32 20130101; C10M 107/34 20130101; C10M
2207/2835 20130101; C10M 2209/043 20130101 |
International
Class: |
C10M 171/00 20060101
C10M171/00; C10M 137/04 20060101 C10M137/04; C10M 105/32 20060101
C10M105/32; C10M 107/34 20060101 C10M107/34; C10M 129/18 20060101
C10M129/18; C10M 169/04 20060101 C10M169/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 28, 2016 |
JP |
2016-148479 |
Claims
1. A refrigerating machine oil comprising: a lubricating base oil;
and a compound represented by the following formula (A):
##STR00021## wherein R.sup.a and R.sup.b each independently
represent a monovalent hydrocarbon group, R.sup.c represents a
divalent hydrocarbon group, X represents a polar group, and Z.sup.a
and Z.sup.b each independently represent oxygen atom or sulfur
atom.
2. The refrigerating machine oil according to claim 1, comprising
at least one oxygen-containing oil selected from the group
consisting of esters and ethers, as the lubricating base oil.
3. The refrigerating machine oil according to claim 1, further
comprising an epoxy compound.
4. The refrigerating machine oil according to claim 3, comprising
at least one selected from the group consisting of glycidyl
ether-based epoxy compounds, glycidyl ester-based epoxy compounds,
oxirane compounds, alkyl oxirane compounds, alicyclic epoxy
compounds, epoxidized fatty acid monoesters, and epoxidized plant
oils, as the epoxy compound.
5. The refrigerating machine oil according to claim 3, comprising
at least one selected from the group consisting of glycidyl
ether-based epoxy compounds, glycidyl ester-based epoxy compounds,
and alicyclic epoxy compounds, as the epoxy compound.
6. The refrigerating machine oil according to claim 1, wherein the
polar group has an oxygen atom.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerating machine
oil.
BACKGROUND ART
[0002] Refrigerating machines such as refrigerators, car
air-conditioners, room air-conditioners, and automatic vending
machines have compressors for circulating refrigerants through
their refrigerating cycles. These compressors are filled with
refrigerating machine oils for lubricating slide members.
Refrigerating machine oils are required to have properties such as
antiwear property and stability.
[0003] Refrigerating machine oils generally contain lubricating
base oils and additives which are selected depending on the
aforementioned required properties. Conventionally, orthophosphate
esters, acid phosphate esters, and the like are used as additives
(antiwear agents) for improving antiwear property (for example, see
Patent Literatures 1 and 2).
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Publication
No. H11-256182
[0005] Patent Literature 2: Japanese Unexamined Patent Publication
No. 2000-282076
SUMMARY OF INVENTION
Technical Problem
[0006] However, there is still a room for improving the antiwear
property of refrigerating machine oils containing an orthophosphate
ester or an acid phosphate ester as an antiwear agent. It is noted
that acid phosphate esters may show higher antiwear property as
compared with orthophosphate esters, but may have a problem in
terms of stability.
[0007] In view of the above circumstances, the present inventors
conducted extensive studies to develop a refrigerating machine oil
having improved antiwear property. That is, an object of the
present invention is to provide a refrigerating machine oil having
excellent antiwear property.
Solution to Problem
[0008] The present invention provides a refrigerating machine oil
including a lubricating base oil and a compound represented by the
following formula (A):
##STR00002##
wherein R.sup.a and R.sup.b each independently represent a
monovalent hydrocarbon group, R.sup.c represents a divalent
hydrocarbon group, X represents a polar group, and Z.sup.a and
Z.sup.b each independently represent oxygen atom or sulfur
atom.
[0009] The refrigerating machine oil preferably includes at least
one oxygen-containing oil selected from the group consisting of
esters and ethers, as the lubricating base oil.
[0010] Preferably, the refrigerating machine oil further includes
an epoxy compound.
[0011] The refrigerating machine oil preferably includes at least
one selected from the group consisting of glycidyl ether-based
epoxy compounds, glycidyl ester-based epoxy compounds, oxirane
compounds, alkyl oxirane compounds, alicyclic epoxy compounds,
epoxidized fatty acid monoesters, and epoxidized plant oils, as the
epoxy compound.
[0012] The refrigerating machine oil preferably includes at least
one selected from the group consisting of glycidyl ether-based
epoxy compounds, glycidyl ester-based epoxy compounds, and
alicyclic epoxy compounds, as the epoxy compound.
[0013] The polar group represented by X in the formula (A)
preferably has an oxygen atom.
Advantageous Effects of Invention
[0014] The present invention can provide a refrigerating machine
oil having excellent antiwear property.
DESCRIPTION OF EMBODIMENTS
[0015] Below, the embodiments of the present invention will be
described in detail.
[0016] A refrigerating machine oil according to one embodiment
includes a lubricating base oil and a compound represented by the
following formula (A):
##STR00003##
wherein R.sup.a and R.sup.b each independently represent a
monovalent hydrocarbon group, R.sup.c represents a divalent
hydrocarbon group, X represents a polar group, and Z.sup.a and
Z.sup.b each independently represent oxygen atom or sulfur
atom.
[0017] As the lubricating base oil, hydrocarbon oils,
oxygen-containing oils, and the like can be used. Examples of the
hydrocarbon oil include mineral oil-based hydrocarbon oils and
synthetic hydrocarbon oils. Examples of the Oxygen-containing oil
include esters, ethers, carbonates, ketones, silicones, and
polysiloxanes.
[0018] Mineral oil-based hydrocarbon oils can be obtained by
refining a lubricant fraction which can be obtained from
atmospheric distillation and vacuum distillation of paraffinic,
naphthenic, or other crude oils according to a method(s) such as
solvent deasphalting, solvent refining, hydrorefining,
hydrogenolysis, solvent dewaxing, hydrodewaxing, clay treatment,
and sulfuric-acid treatment. These refining methods may be used
alone or in combination of two or more.
[0019] Examples of synthetic hydrocarbon oil include alkylbenzenes,
alkylnaphthalenes, poly-.alpha.-olefins (PAO), polybutenes,
ethylene-.alpha.-olefin copolymers, and the like.
[0020] As alkylbenzenes, the following an alkylbenzene (A) and/or
an alkylbenzene (B) can be used.
[0021] The alkylbenzene (A): an alkylbenzene having 1 to 4 alkyl
groups having 1 to 19 carbon atoms in which the total number of
carbon atoms in the alkyl group(s) is 9 to 19 (preferably having 1
to 4 alkyl groups having 1 to 15 carbon atoms in which the total
number of carbon atoms in the alkyl group(s) is 9 to 15).
[0022] The alkylbenzene (B): an alkylbenzene having 1 to 4 alkyl
groups having 1 to 40 carbon atoms in which the total number of
carbon atoms in the alkyl group(s) is 20 to 40 (preferably having 1
to 4 alkyl groups having 1 to 30 carbon atoms in which the total
number of carbon atoms in the alkyl group(s) is 20 to 30)
[0023] Specific examples of the alkyl group(s) having 1 to 19
carbon atoms in the alkylbenzene (A) include, for example, a methyl
group, an ethyl group, a propyl group (including all isomers; the
same applies hereinafter), a butyl group, a pentyl group, a hexyl
group, a heptyl group, an octyl group, a nonyl group, a decyl
group, an undecyl group, a dodecyl group, a tridecyl group, a
tetradecyl group, a pentadecyl group, a hexadecyl group, a
heptadecyl group, an octadecyl group, a nonadecyl group, and an
eicosyl group. These alkyl groups may be linear or branched, and is
preferably branched in view of stability, viscosity properties, and
the like. Especially in view of availability, the alkyl groups are
more preferably branched alkyl groups derived from olefin oligomers
such as propylene, butene, and isobutylene.
[0024] The number of alkyl groups in the alkylbenzene (A) is 1 to
4, but in view of stability and availability, it is preferably 1 or
2 (that is, monoalkylbenzene, dialkylbenzene, or mixtures of
thereof).
[0025] The alkylbenzene (A) may include only one type, of
alkylbenzene having a unitary structure, or may include a mixture
of alkylbenzenes having different structures as long as they
include 1 to 4 alkyl groups having 1 to 19 carbon atoms, and the
total number of carbon atoms in the alkyl group(s) is 9 to 19.
[0026] Specific examples of the alkyl group(s) having 1 to 40
carbon atoms in the alkylbenzene (B) include, for example, a methyl
group, an ethyl group, a propyl group (including all isomers; the
same applies hereinafter), a butyl group, a pentyl group, a hexyl
group, a heptyl group, an octyl group, a nonyl group, a decyl
group, an undecyl group, a dodecyl group, a tridecyl group, a
tetradecyl group, a pentadecyl group, a hexadecyl group, a
heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl
group, a henicosyl group, a docosyl group, a tricosyl group, a
tetracosyl group, a pentacosyl group, a hexacosyl group, a
heptacosyl group, an octacosyl group, a nonacosyl group, a
triacontyl group, a hentriacontyl group, a dotriacontyl group, a
tritriacontyl group, a tetratriacontyl group, a pentatriacontyl
group, a hexatriacontyl group, a heptatriacontyl group, an
octatriacontyl group, a nonatriacontyl group, and a tetracontyl
group. These alkyl groups may be linear or branched, and is
preferably branched in view of stability, viscosity properties, and
the like. Especially in view of availability, the alkyl groups are
more preferably branched alkyl groups derived from olefin oligomers
such as propylene, butene, and isobutylene. In view of a higher
flash point, the alkyl groups are more preferably linear or
branched alkyl groups derived from linear alkylating agents such as
normal paraffin, normal-.alpha.-olefin, or halides thereof, and are
even more preferably branched alkyl groups.
[0027] The number of alkyl groups in the alkylbenzene (B) is 1 to
4, but in view of stability and availability, it is preferably 1 or
2 (that is, monoalkylbenzene, dialkylbenzene, or mixtures of
thereof).
[0028] The alkylbenzene (B) may include only one type of
alkylbenzene having a unitary structure, or may include a mixture
of alkylbenzenes having different structures as long as they
include 1 to 4 alkyl group(s) having 1 to 40 carbon atoms, and the
total number of carbon atoms in the alkyl group(s) is 20 to 40.
[0029] A poly-.alpha.-olefins (PAO) can be obtained as follows: for
example, several molecules of a linear olefin having 6 of 18 having
a double bond only at one end are polymerized, and then
hydrogenated. The poly-.alpha.-olefin may be an isoparaffin having
a molecular weight distribution mainly including, for example, a
trimer or tetramer of .alpha.-decene having 10 carbon atoms or
.alpha.-dodecene having 12 carbon atoms.
[0030] Examples of the ester include aromatic esters, dibasic acid
esters, polyol esters, complex esters, carbonate esters, and
mixtures thereof. The ester is preferably a polyol ester or complex
ester.
[0031] Polyol esters are esters of polyhydric alcohols and fatty
acids. As the fatty acids, saturated fatty acids are preferably
used. The number of carbon atoms of the fatty acids is preferably 4
to 20, more preferably 4 to 18, even more preferably 4 to 9, and in
particular preferably 5 to 9. The polyol esters may be partial
esters in which some of the hydroxy groups of a polyhydric alcohol
remain unesterified, or may be complete esters in which all hydroxy
groups are esterified, or may be mixtures of partial esters and
complete esters. The polyol esters preferably have a hydroxy value
of 10 mg KOH/g or less, more preferably 5 mg KOH/g or less, and
even more preferably 3 mg KOH/g or less.
[0032] The ratio of fatty acids having 4 to 20 carbon atoms is
preferably 20 to 100% by mol based on the total fatty acids of a
poly ester, more preferably 50 to 100% by mol, even more preferably
70 to 100% by mol, and in particular preferably 90 to 100% by
mol.
[0033] Specifically, fatty acids having 4 to 20 carbon atoms
include butanoic acid, pentanoic acid, hexanoic acid, heptanoic
acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid,
dodecanoic acid, tridecanoic acid, tetradecanoic acid,
pentadecanoic acid, hexadecanoic acid, heptadecanoic acid,
octadecanoic acid, nonadecanoic acid, and icosanoic acid. These
fatty acids may be linear or branched. The fatty acids are
preferably branched at the .alpha. and/or .beta. positions, and
more preferably selected from 2-methylpropanoic acid,
2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic
acid, 2-ethylpentanoic acid, 2-methylheptanoic acid,
2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and
2-ethylhexadecanoic acid, and even more preferably selected from
2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid.
[0034] The fatty acids may include fatty acids other than those
having 4 to 20 carbon atoms. For example, the fatty acids other
than those having 4 to 20 carbon atoms may have 21 to 24 carbon
atoms. The fatty acids having 21 to 24 carbon atoms may be
heneicosanoic acid, docosanoic acid, tricosanoic acid,
tetracosanoic acid, and the like, and may be linear or
branched.
[0035] As a polyhydric alcohol of the polyol esters, a polyhydric
alcohol having 2 to 6 hydroxy groups is preferably used. The number
of carbon atoms in the polyhydric alcohol is preferably 4 to 12,
more preferably 5 to 10. The polyhydric alcohol is preferably a
hindered alcohol such as neopentyl glycol, trimethylolethane,
trimethylolpropane, trimethylolbutane, di-(trimethylolpropane),
tri-(trimethylolpropane), pentaerythritol, and dipentaerythritol.
It is more preferably pentaerythritol, dipentaerythritol, or an
alcohol mixture of pentaerythritol and dipentaerythritol in view of
compatibility with a refrigerant and hydrolytic stability.
[0036] Complex esters may be synthesized, for example, by the
following method (a) or (b):
[0037] (a) a method including: adjusting the molar ratio of a
polyhydric alcohol and a polybasic acid, and synthesizing an ester
intermediate in which some of the carboxyl groups of the polybasic
acid remain unesterified, and then esterifying the remaining
carboxyl groups with a monohydric alcohol;
[0038] (b) a method including: adjusting the molar ratio of a
polyhydric alcohol and a polybasic acid, and synthesizing an ester
intermediate in which some of the hydroxy groups of the polyhydric
alcohol remain unesterified, and then esterifying the remaining
hydroxy groups with a monovalent fatty acid.
[0039] A complex ester obtained by the method (b) may produce a
relatively strong acid upon hydrolysis during use as a
refrigerating machine oil, and thus tends to show somewhat inferior
stability as compared with a complex ester obtained by the method
(a). Therefore, complex esters for use herein are preferably those
obtained by the method (a) which can provide more stable
products.
[0040] The complex ester is preferably synthesized from at least
one selected from polyhydric alcohols having 2 to 4 hydroxy groups,
at least one selected from polybasic acids having 6 to 12 carbon
atoms, and at least one selected from monohydric alcohols having 4
to 18 carbon atoms and monovalent fatty acids having 2 to 12 carbon
atoms.
[0041] Examples of the polyhydric alcohols having 2 to 4 hydroxy
groups include neopentyl glycol, trimethylolpropane,
pentaerythritol, and the like. The polyhydric alcohols having 2 to
4 hydroxy groups are preferably selected from neopentyl glycol and
trimethylolpropane, and more preferably are neopentyl glycol
because suitable viscosity can be secured, and good low-temperature
properties can be obtained in combination with a complex ester used
as a base oil.
[0042] Preferably, the polyhydric alcohol of a complex ester
further include a dihydric alcohol having 2 to 10 carbon atoms
other than neopentyl glycol in addition to the polyhydric alcohol
having 2 to 4 hydroxy groups. Examples of the dihydric alcohol
having 2 to 10 carbon atoms other than neopentyl glycol include
ethylene glycol, propanediols, butanediol, pentanediol, hexanediol,
2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol,
2,2-diethyl-1,3-pentanediol, and the like. The above dihydric
alcohol is preferably butanediol in view of excellent properties as
a lubricating base oil. Examples of butanediol include
1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, and
the like. Butanediol is preferably selected from 1,3-butanediol and
1,4-butanediol in order to obtain good properties. The amount of a
dihydric alcohol having 2 to 10 carbon atoms other than neopentyl
glycol is preferably 1.2 mol or less, more preferably 0.8 mol or
less, and even more preferably 0.4 mol or less, based on 1 mol of
the polyhydric alcohol having 2 to 4 hydroxy groups.
[0043] Examples of the polybasic acids having 6 to 12 carbon atoms
include adipic acid, pimelic acid, suberic acid, azelaic acid,
sebacic acid, phthalic acid, trimellitic acid, and the like. In
view of balanced properties of synthesized esters and availability,
the above polybasic acids are preferably selected from adipic acid
and sebacic acid, and more preferably is adipic acid. The amount of
a polybasic acid having 6 to 12 carbon atoms is preferably 0.4 mol
to 4 mol, more preferably 0.5 mol to 3 mol, and even more
preferably 0.6 mol to 2.5 mol, based on 1 mol of the polyhydric
alcohol having 2 to 4 hydroxy groups.
[0044] Examples of the monohydric alcohols having 4 to 18 carbon
atoms include aliphatic alcohols such as butanol, pentanol,
hexanol, heptanol, octanol, nonanol, decanol, dodecanol, and oleyl
alcohol. These monohydric alcohols may be linear or branched.
Especially in view of balanced properties, the monohydric alcohols
having 4 to 18 carbon atoms are preferably monohydric alcohols
having 6 to 10 carbon atoms, more preferably monohydric alcohols
having 8 to 10 carbon atoms. The above monohydric alcohols are more
preferably selected from 2-ethylhexanol and 3,5,5-trimethylhexanol
because the resulting synthesized complex ester will have good
low-temperature properties.
[0045] Examples of the monovalent fatty acids having 2 to 12 carbon
atoms include ethanoic acid, propanoic acid, butanoic acid,
pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid,
nonanoic acid, decanoic acid, dodecanoic acid, and the like. These
monovalent fatty acids may be linear or branched. The monovalent
fatty acids having 2 to 12 carbon atoms are preferably monovalent
fatty acids having 8 to 10 carbon atoms. Among these,
2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid are more
preferred in view of low-temperature properties.
[0046] Examples of the ether include polyvinyl ether, polyalkylene
glycol, polyphenyl ether, perfluoroether, and mixtures thereof, and
the like. The ether is preferably selected from polyvinyl ethers
and polyalkylene glycols, and more preferably a polyvinyl
ether.
[0047] The polyvinyl ether has a structural unit represented by the
following formula (1):
##STR00004##
wherein R.sup.1, R.sup.2, and R.sup.3 may be the same or different
from each other, and each represent a hydrogen atom or a
hydrocarbon group, and R.sup.4 represents a divalent hydrocarbon
group or a divalent ether-linked oxygen-containing hydrocarbon
group, and R.sup.5 represents a hydrocarbon group, and m represents
an integer of 0 or higher. When m is 2 or higher, multiple R.sup.4s
may be the same or different from each other.
[0048] The number of carbon atoms of hydrocarbon groups represented
by R.sup.1, R.sup.2, and R.sup.3 is preferably 1 or more, more
preferably 2 or more, and even more preferably 3 or more, and are
also preferably 8 or less, more preferably 7 or less, and even more
preferably 6 or less. At least one of R.sup.1, R.sup.2, and R.sup.3
is preferably a hydrogen atom, and more preferably, all of R.sup.1,
R.sup.2, and R.sup.3 are hydrogen atoms.
[0049] The number of carbon atoms of a divalent hydrocarbon group
and ether-linked oxygen-containing hydrocarbon group represented by
R.sup.4 is preferably 1 or more, more preferably 2 or more, and
even more preferably 3 or more, and are also preferably 10 or less,
more preferably 8 or less, and even more preferably 6 or less. The
divalent ether-linked oxygen-containing hydrocarbon group
represented by R.sup.4, for example, may have oxygen on a side
chain which can form an ether linkage.
[0050] R.sup.5 is preferably a hydrocarbon group having 1 to 20
carbon atoms. Examples of this hydrocarbon group include an alkyl
group, a cycloalkyl group, a phenyl group, an aryl group, an
arylalkyl group, and the like. The above hydrocarbon group is
preferably an alkyl group, more preferably an alkyl group having 1
to 5 carbon atoms.
[0051] m is preferably 0 or higher, more preferably 1 or higher,
and even more preferably 2 or higher, and is also preferably 20 or
lower, more preferably 18 or lower, and even more preferably 16 or
lower. The average value of m in the entire structure units of the
polyvinyl ether is preferably 0 to 10.
[0052] The polyvinyl ether may be a homopolymer including one
selected from the structural units represented by the formula (1),
or may be a copolymer including two or more selected from the
structural units represented by the formula (1), or may be a
copolymer including a structural unit represented by the formula
(1) and a different structural unit. When the polyvinyl ether is a
copolymer, lubricity, insulation properties, hygroscopicity, and
the like can be further improved while satisfying compatibility of
a refrigerating machine oil with a refrigerant. Under these
circumstances, appropriately selecting the type of a raw monomer,
the type of an initiator, the ratio of structural units in a
copolymer, and the like can confer the aforementioned various
properties on the resulting refrigerating machine oil. The
copolymer may be either a block copolymer or a random
copolymer.
[0053] When the polyvinyl ether is a copolymer, the copolymer
preferably has a structural unit (1-1) represented by the above
formula (1) in which R.sup.5 is an alkyl group having 1 to 3 carbon
atoms and a structural unit (1-2) represented by the above formula
(1) in which R.sup.5 is an alkyl group having 3 to 20, preferably 3
to 10, and more preferably 3 to 8 carbon atoms. R.sup.5 in the
structural unit (1-1) is in particular preferably an ethyl group
while R.sup.5 in the structural unit (1-2) is in particular
preferably an isobutyl group. When the polyvinyl ether is a
copolymer having the above structural units (1-1) and (1-2), the
molar ratio of the structural unit (1-1) and the structural unit
(1-2) is preferably 5:95 to 95:5, more preferably 20:80 to 90:10,
and even more preferably 70:30 to 90:10. When the above molar ratio
falls within the above ranges, compatibility with a refrigerant
tends to be able to be further improved, and hygroscopicity tends
to be able to be lowered.
[0054] The polyvinyl ether may consist only of a structural unit
represented by the above formula (1), or may be a copolymer further
including a structural unit represented by the following formula
(2):
##STR00005##
wherein R.sup.6 to R.sup.9 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. In the latter case, the copolymer may
be either a block copolymer or a random copolymer.
[0055] The polyvinyl ether may be manufactured by polymerizing a
vinyl ether-base monomer corresponding to a structural unit
represented by the formula (1), or by copolymering a vinyl
ether-base monomer corresponding to a structural unit represented
by the formula (1) with a hydrocarbon monomer having an olefinic
double bond corresponding to a structural unit represented by the
formula (2). As the vinyl ether-based monomer corresponding to a
structural unit represented by the formula (1), a monomer
represented by the following formula (3) is suitable:
##STR00006##
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and m each
have the same definitions as defined for R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, and m in the formula (1).
[0056] The polyvinyl ether preferably has the following terminal
structure (A) or (B).
[0057] (A) A structure in which one end is represented by the
formula (4) or (5) while the other end is represented by the
formula (6) or (7).
##STR00007##
In the formula (4), R.sup.11, R.sup.21, and R.sup.31 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, and
R.sup.41 represents a divalent hydrocarbon group having 1 to 10
carbon atoms or a divalent ether-linked oxygen-containing
hydrocarbon group, and R.sup.51 represents a hydrocarbon group
having 1 to 20 carbon atoms, and m has the same definition as
defined for m in the formula (1). When m is 2 or higher, multiple
R.sup.41s may be the same or different from each other.
##STR00008##
In the formula (5), R.sup.61, R.sup.71, R.sup.81, and R.sup.91 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.
##STR00009##
In the formula (6), R.sup.12, R.sup.22, and R.sup.32 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, and
R.sup.42 represents a divalent hydrocarbon group or divalent
ether-linked oxygen-containing hydrocarbon group having 1 to 10
carbon atoms, and R.sup.52 represents a hydrocarbon group having 1
to 20 carbon atoms, and m has the same definition as defined for m
in the formula (1). When m is 2 or higher, multiple R.sup.42s may
be the same or different from each other.
##STR00010##
In the formula (7), R.sup.62, R.sup.72, R.sup.82, and R.sup.92 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.
[0058] (B) A structure in which one end is represented by the above
formula (4) or (5) while the other end is represented by the
following formula (8):
##STR00011##
wherein R.sup.13, R.sup.23, and R.sup.33 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.
[0059] Among these polyvinyl ethers, those of (a), (b), (c), (d),
and (e) listed below are particularly suitable as a base oil.
[0060] (a) A polyvinyl ether having a structure in which one end is
represented by the formula (4) or (5), and the other end is
represented by the formula (6) or (7), in which R.sup.1, R.sup.2,
and R.sup.3 in the formula (1) are each a hydrogen atom, and m is
an integer of 0 to 4, and R.sup.4 is a divalent hydrocarbon group
having 2 to 4 carbon atoms, and R.sup.5 is a hydrocarbon group
having 1 to 20 carbon atoms.
[0061] (b) A polyvinyl ether including only a structural unit
represented by the formula (1) and having a structure in which one
end is represented by the formula (4), and the other end is
represented by the formula (6), in which R.sup.1, R.sup.2, and
R.sup.3 in the formula (1) are each a hydrogen atom, and m is an
integer of 0 to 4, and R.sup.4 is a divalent hydrocarbon group
having 2 to 4 carbon atoms, and R.sup.5 is a hydrocarbon group
having 1 to 20 carbon atoms.
[0062] (c) A polyvinyl ether having a structure in which one end is
represented by the formula (4) or (5), and the other end is
represented by the formula (8), in which R.sup.1, R.sup.2, and
R.sup.3 in the formula (1) are each a hydrogen atom, and m is an
integer of 0 to 4, and R.sup.4 is a divalent hydrocarbon group
having 2 to 4 carbon atoms, and R.sup.5 is a hydrocarbon group
having 1 to 20 carbon atoms.
[0063] (d) A polyvinyl ether including only a structural unit
represented by the formula (1) and having a structure in which one
end is represented by the formula (5), and the other end is
represented by the formula (8), in which R.sup.1, R.sup.2, and
R.sup.3 in the formula (1) are each a hydrogen atom, and m is an
integer of 0 to 4, and R.sup.4 is a divalent hydrocarbon group
having 2 to 4 carbon atoms, and R.sup.5 is a hydrocarbon group
having 1 to 20 carbon atoms.
[0064] (e) A polyvinyl ether of any of the above (a), (b), (c) and
(d) having a structural unit in which R.sup.5 in the formula (1) is
a hydrocarbon group having 1 to 3 carbon atoms and a structural
unit in which that R.sup.5 is a hydrocarbon group having 3 to 20
carbon atoms.
[0065] The weight average molecular weight of the polyvinyl ether
is preferably 500 or more, more preferably 600 or more, and is also
preferably 3000 or less, more preferably 2000 or less, and even
more preferably 1500 or less. When the polyvinyl ether has a weight
average molecular weight of 500 or more, superior lubricity in the
presence of a refrigerant can be obtained. A weight average
molecular weight of 3000 or less enables a wider range of
compositions within which compatibility with a refrigerant can be
obtained under low-temperature conditions, preventing poor
lubrication in a refrigerant compressor and deteriorated heat
exchange in an evaporator.
[0066] The number average molecular weight of the polyvinyl ether
is preferably 500 or more, more preferably 600 or more, and is also
preferably 3000 or less, more preferably 2000 or less, and even
more preferably 1500 or less. When the polyvinyl ether has a number
average molecular weight of 500 or more, superior lubricity in the
presence of a refrigerant can be obtained. A number average
molecular weight of 3000 or less enables a wider range of
compositions within which compatibility with a refrigerant can be
obtained under low-temperature conditions, preventing poor
lubrication in a refrigerant compressor and deteriorated heat
exchange in an evaporator.
[0067] The weight average molecular weight and number average
molecular weight of the polyvinyl ether both are those determined
by the GPC analysis (in terms of polystyrene (standard sample)).
For example, the weight average molecular weight and number average
molecular weight can be measured as follows.
[0068] Dilution is performed using chloroform as a solvent to
prepare a solution with a polyvinyl-ether concentration of 1% by
mass. The solution is analyzed with a GPC instrument (Waters
Alliance 2695). Analysis is performed with a refractive index
detector at a solvent flow rate of 1 ml/min using a column capable
of analyzing a molecular weight of 100 to 10000. It is noted that
the relationship between column relation time and molecular weight
is separately determined using a polystyrene standard having a
known molecular weight to create a calibration curve, and the
molecular weight of a sample is then determined from a measured
retention time.
[0069] The polyvinyl ether preferably has a degrees of unsaturation
of 0.04 meq/g or less, more preferably 0.03 meq/g or less, and even
more preferably 0.02 meq/g or less. The polyvinyl ether preferably
has a peroxide value of a 10.0 meq/kg or less, more preferably 5.0
meq/kg or less, and even more preferably 1.0 meq/kg or less. The
polyvinyl ether preferably has a carbonyl value of 100 ppm by
weight or less, more preferably 50 ppm by weight or less, and even
more preferably 20 ppm by weight or less. The polyol ester
preferably has a hydroxy value of 10 mg KOH/g or less, more
preferably 5 mg KOH/g or less, and even more preferably 3 mg KOH/g
or less.
[0070] The degree of unsaturation, peroxide value, and carbonyl
value in the present invention each refer to a value measured in
accordance with the Standard Methods for the Analysis of Fats, Oils
and Related Materials defined by the Japan Oil Chemists' Society.
That is, with regard to the degree of unsaturation in the present
invention, a sample is allowed to react with a Wij's solution (a
solution of ICl-acetic acid), and left stand in a dark place, and
then excess ICl is reduced into iodine, and that iodine is
subsequently titrated with sodium thiosulfate to calculate an
iodine value. The iodine value is then converted into a value
(meq/g) in terms of vinyl equivalent. This value is used as the
degree of unsaturation. With regard to the peroxide value in the
present invention, potassium iodide is added to a sample, and the
resulting free iodine is titrated with sodium thiosulfate, and the
amount of the free iodine determined is converted into a value
(meq/kg) in milliequivalent per kg of the sample. This value is
used as the peroxide value. With regard to the carbonyl value in
the present invention, a sample is allowed to react with
2,4-dinitrophenylhydrazine to generate chromogenic quinonoid ions.
The absorbance of the sample at 480 nm is measured and converted
into a value (ppm by weight) in terms of the amount of carbonyl
based on a calibration curve which is pre-determined using
cinnamaldehyde as the standard substance. This value is used as the
carbonyl value. The hydroxy value in the present invention is
measured in accordance with JIS K0070:1992.
[0071] Examples of polyalkylene glycols include polyethylene
glycol, polypropylene glycol, polybutylene glycol, and the like.
Polyalkylene glycols have oxyethylene, oxypropylene, oxybutylene,
and the like as structural units. Polyalkylene glycols having these
structural units can be obtained by ring-opening polymerization of
ethylene oxide, propylene oxide, or butylene oxide as a raw monomer
material.
[0072] Examples of the polyalkylene glycol include compounds
represented by the following formula (9):
R.sup..alpha.--[(OR.sup..beta.).sub.f--OR.sup..gamma.].sub.g
(9)
wherein in the formula (9), R.sup..alpha. represents a hydrogen
atom, an alkyl group having 1 to 10 carbon atoms, an acyl group
having 2 to 10 carbon atoms, or a residue of a compound having 2 to
8 hydroxy groups, and R.sup..beta. represents an alkylene group
having 2 to 4 carbon atoms, R.sup..gamma. represents a hydrogen
atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group
having 2 to 10 carbon atoms, and f represents an integer of 1 to
80, and g represents an integer of 1 to 8.
[0073] The alkyl groups represented by R.sup..alpha. and
R.sup..gamma. may be any of linear, branched, or cyclic. The number
of carbon atoms of these alkyl groups is preferably 1 to 10, more
preferably 1 to 6. When these alkyl groups have more than 10 carbon
atoms, compatibility with a refrigerant tends to be decreased.
[0074] The alkyl-group moieties of the acyl groups represented by
R.sup..alpha. and R.sup..gamma. may be any of linear, branched, or
cyclic. The number of carbon atoms of the acyl groups is preferably
2 to 10, more preferably 2 to 6. When the above acyl groups have
more than 10 carbon atoms, compatibility with a refrigerant may be
decreased, resulting in phase separation.
[0075] When the groups represented by R.sup..alpha. and
R.sup..gamma. are both alkyl groups or both acyl groups, the groups
represented by R.sup..alpha. and R.sup..gamma. may be the same or
different. When g is 2 or higher, the multiple groups represented
by R.sup..alpha. and R.sup..gamma. in the same molecule may be the
same or different.
[0076] When the group represented by R.sup..alpha. is a residue of
a compound having 2 to 8 hydroxy groups, this compound may be
chain-like or cyclic.
[0077] In view of excellent compatibility, at least one of
R.sup..alpha. and R.sup..gamma. is preferably an alkyl group, more
preferably an alkyl group having 1 to 4 carbon atoms, and even more
preferably a methyl group. In view of excellent heat and chemical
stability, both of R.sup..alpha. and R.sup..gamma. are preferably
an alkyl group, more preferably an alkyl group having 1 to 4 carbon
atoms, and even more preferably a methyl group. In view of
manufacturability and cost, preferably, one of R.sup..alpha. or
R.sup..gamma. is an alkyl group (more preferably an alkyl group
having 1 to 4 carbon atoms) while the other is a hydrogen atom.
More preferably, one is a methyl group while the other is a
hydrogen atom. In view of excellent lubricity and sludge
solubility, both of R.sup..alpha. and R.sup..gamma. are hydrogen
atoms.
[0078] R.sup..beta. represents an alkylene group having 2 to 4
carbon atoms. Specific examples of such an alkylene group include
an ethylene group, a propylene group, a butylene group, and the
like. Further, oxyalkylene groups as repeating units represented by
OR.sup..beta. include an oxyethylene group, an oxypropylene group,
and an oxybutylene group. The oxyalkylene groups represented by
(OR.sup..beta.).sub.f may be composed of one type of oxyalkylene
group, or may be composed of two or more types of oxyalkylene
group.
[0079] The polyalkylene glycol represented by the formula (9) is
preferably a copolymer including an oxyethylene group (EO) and an
oxypropylene group (PO) in view of excellent compatibility with a
refrigerant and viscosity-temperature properties. In this case, the
ratio (EO/(PO+EO)) of the oxyethylene group to the total of the
oxyethylene group and the oxypropylene group is preferably 0.1 to
0.8, more preferably 0.3 to 0.6 in view of excellent seizure load
and viscosity-temperature properties. In view of excellent
hygroscopicity and heat/oxidation stability, EO/(PO+EO) is
preferably 0 to 0.5, more preferably 0 to 0.2, even more preferably
0 (that is, a propylene oxide homopolymer).
[0080] f represents the number of repeats (the degree of
polymerization) of the oxyalkylene group OR.sup..beta., and is an
integer of 1 to 80. g is an integer of 1 to 8. For example, g is 1
when R.sup..alpha. is an alkyl group or an acyl group. When
R.sup..alpha. is a residue of a compound having 2 to 8 hydroxy
groups, g corresponds to the number of hydroxy groups in that
compound.
[0081] In the polyalkylene glycol represented by the formula (9),
the average value of the product (f.times.g) of f and g is
preferably 6 to 80 because it will well satisfy required
performances as a refrigerating machine oil in a balanced
manner.
[0082] The weight average molecular weight of the polyalkylene
glycol is preferably 500 or more, more preferably 600 or more, and
is also preferably 3000 or less, more preferably 2000 or less, and
even more preferably 1500 or less. When the polyalkylene glycol has
a weight average molecular weight of 500 or more, superior
lubricity in the presence of a refrigerant can be obtained. A
weight average molecular weight of 3000 or less enables a wider
range of compositions within which compatibility with a refrigerant
can be obtained under low-temperature conditions, preventing poor
lubrication in a refrigerant compressor and deteriorated heat
exchange in an evaporator.
[0083] The number average molecular weight of the polyalkylene
glycol is preferably 500 or more, more preferably 600 or more, and
is also preferably 3000 or less, more preferably 2000 or less, and
even more preferably 1500 or less. When the polyalkylene glycol has
a number average molecular weight of 500 or more, superior
lubricity in the presence of a refrigerant can be obtained. A
number average molecular weight of 3000 or less enables a wider
range of compositions within which compatibility with a refrigerant
can be obtained under low-temperature conditions, preventing poor
lubrication in a refrigerant compressor and deteriorated heat
exchange in an evaporator.
[0084] The weight average molecular weight and number average
molecular weight of the polyalkylene glycol are both those
determined by GPC analysis (in terms of polypropylene glycol
(standard sample)). For example, the weight average molecular
weight and number average molecular weight can be determined as
follows.
[0085] Dilution is performed using chloroform as a solvent to
prepare a solution with a polyalkylene-glycol concentration of 1%
by mass. The solution is analyzed with a GPC instrument (Waters
Alliance 2695). Analysis is performed with a refractive index
detector at a solvent flow rate of 1 ml/min using a column capable
of analyzing a molecular weight of 100 to 10000. It is noted that
the relationship between column relation time and molecular weight
is separately determined using a polyalkylene glycol standard
having a known molecular weight to create a calibration curve, and
the molecular weight of a sample is then determined from a measured
retention time.
[0086] The hydroxy value of the polyalkylene glycol is preferably
100 mg KOH/g or less, more preferably 50 mg KOH/g or less, even
more preferably 30 mg KOH/g or less, and most preferably 10 mg
KOH/g or less.
[0087] The polyalkylene glycol can be synthesized by a known method
(Mitsuta Shibata et al., "alkylene oxide polymer," Kaibundo
Publishing Co., Ltd., Nov. 20, 1990). For example, one or more
predetermined alkylene oxides are addition-polymerized with an
alcohol (R.sup..alpha.OH; R.sup..alpha. has the same definition as
defined for R.sup..alpha. in the formula (9)), and terminal
hydroxyl groups are further etherified or esterified to obtain the
polyalkylene glycol represented by the formula (9). When two or
more alkylene oxides are used in the above manufacturing process,
the resulting polyalkylene glycol may be either a random copolymer
or a block copolymer. However, it is preferably a block copolymer
in view of the tendency of having superior oxidation stability and
lubricity, and preferably a random copolymer in view of the
tendency of having superior low-temperature fluidity.
[0088] The polyalkylene glycol preferably has a degrees of
unsaturation of 0.04 meq/g or less, more preferably 0.03 meq/g or
less, and even more preferably 0.02 meq/g or less. The polyalkylene
glycol preferably has a peroxide value of a 10.0 meq/kg or less,
more preferably 5.0 meq/kg or less, and even more preferably 1.0
meq/kg or less. The polyalkylene glycol preferably has a carbonyl
value of 100 ppm by weight or less, more preferably 50 ppm by
weight, and even more preferably 20 ppm by weight or less.
[0089] The lubricating base oil is preferably at least one selected
from oxygen-containing oils, more preferably at least one selected
from esters and ethers.
[0090] The kinematic viscosity at 40.degree. C. of the lubricating
base oil may be preferably 3 mm.sup.2/s or more, more preferably 4
mm.sup.2/s or more, and even more preferably 5 mm.sup.2/s or more.
The kinematic viscosity at 40.degree. C. of the lubricating base
oil may be preferably 1000 mm.sup.2/s or less, more preferably 500
mm.sup.2/s or less, and even more preferably 400 mm.sup.2/s or
less. The kinematic viscosity at 100.degree. C. of the lubricating
base oil may be preferably 1 mm.sup.2/s or more, and more
preferably 2 mm.sup.2/s or more. The kinematic viscosity at
100.degree. C. of the lubricating base oil may be preferably 100
mm.sup.2/s or less, and more preferably 50 mm.sup.2/s or less. The
kinematic viscosity in the present invention is measured in
accordance with JIS K2283:2000.
[0091] The content of the lubricating base oil may be 50% by mass
or more, 60% by mass or more, 70% by mass or more, 80% by mass or
more, or 90% by mass or more based on the total amount of the
refrigerating machine oil.
[0092] The compound represented by the formula (A) is preferably
represented by any of the following formulae (A-1) to (A-3):
##STR00012##
wherein R.sup.a, R.sup.b, R.sup.c, and X have the same meaning as
R.sup.a, R.sup.b, R.sup.c, and X in the formula (A),
respectively.
[0093] The number of carbon atoms of the monovalent hydrocarbon
groups represented by R.sup.a and R.sup.b may be 2 to 18, 2 to 16,
2 to 14, 2 to 12, 2 to 10, or 2 to 8. The monovalent hydrocarbon
groups may be linear or branched alkyl groups. The number of carbon
atoms in the divalent hydrocarbon group represented by R.sup.c may
be 1 to 4, 1 to 3, 1 to 2, or 1. The divalent hydrocarbon group may
be a linear or branched alkylene group.
[0094] The polar group represented by X may have an oxygen atom.
For example, the polar group may be any of --OH group, --COOH
group, a --COOR group, --CONHNH.sub.2 group, --CONH.sub.2 group, a
--NR.sub.2 group, --CN group, --CH(COOH)CH.sub.2COOH group, a
--CH(COOR)CH.sub.2COOH group, or any of groups represented by the
following Formulae (x-1) to (x-4):
##STR00013##
[0095] The polar group represented by X is preferably --OH group,
--COOH group, --COOR group, --CH(COOH)CH.sub.2COOH group, or
--CH(COOR)CH.sub.2COOH group. Each R in the above --COOR group,
--NR.sub.2 group, and --CH(COOR)CH.sub.2COOH group may be a
monovalent hydrocarbon group, and may be a linear or branched alkyl
group. The number of carbon atoms of the above monovalent
hydrocarbon groups and alkyl groups may be 1 to 12, 1 to 8, or 1 to
2.
[0096] In a preferred aspect, the compound represented by the
formula (A) may be a compound represented by the following formula
(A-4):
##STR00014##
wherein R.sup.d and R.sup.e each represent a linear or branched
alkyl group having 2 to 8 carbon atoms, and X.sup.a represents --OH
group, --COOH group, or --COOR' group (wherein R' represents a
linear or branched alkyl, group having 1 to 8 carbon atoms).
[0097] The content of the compound represented by the formula (A)
may be 0.005% by mass or more, 0.01% by mass or more, or 0.02% by
mass or more, and may be 0.1% by mass or less, 0.2% by mass or
less, or 1% by mass or less, based on the total amount of the
refrigerating machine oil. The content of the compound represented
by the formula (A) may be 0.005 to 0.1% by mass, 0.005 to 0.2% by
mass, 0.005 to 1% by mass; 0.01 to 0.1% by mass, 0.01 to 0.2% by
mass, 0.01 to 1% by mass, 0.02 to 0.1% by mass, 0.02 to 0.2% by
mass, or 0.02 to 1% by mass, based on the total amount of the
refrigerating machine oil.
[0098] The refrigerating machine oil may further include an epoxy
compound. Examples of the epoxy compound include a glycidyl
ether-based epoxy compound, a glycidyl ester-based epoxy compound,
an oxirane compound, an alkyl oxirane compound, an alicyclic epoxy
compound, an epoxidized fatty acid monoester, an epoxidized plant
oil, and the like. These epoxy compounds are used alone or in
combination of two or more.
[0099] The glycidyl ether-based epoxy compound may be, for example,
an aryl glycidyl ether-based epoxy compound or an alkyl glycidyl
ether-based epoxy compound, which are represented by the following
Formula (B-1):
##STR00015##
wherein R.sup.f represents an aryl group having 6 to 18 carbon
atoms or an alkyl group having 5 to 18 carbon atoms.
[0100] The glycidyl ether-based epoxy compound represented by the
formula (B-1) is preferably n-butylphenyl glycidyl ether,
i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether,
tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether,
hexylphenyl glycidyl ether, heptylphenyl glycidyl ether,
octylphenyl glycidyl ether, nonylphenyl glycidyl ether, decylphenyl
glycidyl ether, decyl glycidyl ether, undecyl glycidyl ether,
dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl
glycidyl ether, or 2-ethylhexyl glycidyl ether.
[0101] The glycidyl ether-based epoxy compound may be a compound
other than the epoxy compound represented by the formula (B-1), and
specifically, may be neopentyl glycol diglycidyl ether,
trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl
ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl
ether, polyalkylene glycol monoglycidyl ether, polyalkylene glycol
diglycidyl ether, and the like.
[0102] The glycidyl ester-based epoxy compound may be, for example,
a compound represented by the following formula (B-2):
##STR00016##
wherein R.sup.g represents an aryl group having 6 to 18 carbon
atoms, an alkyl group having 5 to 18 carbon atoms, or an alkenyl
group having 5 to 18 carbon atoms.
[0103] The glycidyl ester-based epoxy compound represented by the
formula (B-2) is preferably glycidyl benzoate, glycidyl
neodecanoate, glycidyl-2,2-dimethyl octanoate, glycidyl acrylate,
or glycidyl methacrylate.
[0104] The alicyclic epoxy compound has a substructure represented
by the following formula (B-3):
##STR00017##
in which the carbon atoms of an epoxy group directly constitutes an
alicyclic ring.
[0105] The alicyclic epoxy compound may be, for example,
1,2-epoxycyclohexane, 1,2-epoxycyclopentane,
3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate,
bis(3,4-epoxycyclohexylmethyl)adipate, exo-2,3-epoxynorbornane,
bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate,
2-(7-oxabicyclo[4.1.0]hept-3-yl)-spiro(1,3-dioxane-5,3'-[7]oxabicyclo[4.1-
.0]heptane, 4-(1'-methylepoxyethyl)-1,2-epoxy-2-methylcyclohexane,
or 4-epoxyethyl-1,2-epoxycyclohexane.
[0106] Examples of the allyl oxirane compound include
1,2-epoxystyrene, alkyl-1,2-epoxystyrene, and the like.
[0107] Examples of the alkyl oxirane compound include,
1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane,
1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane,
1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane,
1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane,
1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,2-epoxyoctadecane,
1,2-epoxynonadecane, 1,2-epoxyicosane, and the like.
[0108] Examples of the epoxidized fatty acid monoester include
esters of an epoxidized fatty acid having 12 to 20 carbon atoms and
an alcohol having 1 to 8 carbon atoms or phenol or alkylphenol. The
epoxidized fatty acid monoester is preferably butyl epoxystearate,
hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl, or
butylphenyl ester.
[0109] Examples of the epoxidized plant oil include epoxy compounds
of plant oils such as soybean oil, linseed oil, and cottonseed oil;
and the like.
[0110] When the refrigerating machine oil includes both the
compound represented by the formula (A) and the epoxy compound, the
refrigerating machine oil has not only excellent antiwear property
but also excellent stability as compared with a conventional
refrigerating machine oil including, for example, an acid phosphate
ester and an epoxy compound. In view of simultaneous achievement of
antiwear property and stability, the epoxy compound is preferably
at least one selected from glycidyl ether-based epoxy compounds,
glycidyl ester-based epoxy compounds, and alicyclic epoxy
compounds, and is more preferably at least one selected from
glycidyl ether-based epoxy compounds and glycidyl ester-based epoxy
compounds.
[0111] In view of improved stability, the content of the epoxy
compound is preferably 0.1% by mass or more, more preferably 0.15%
by mass or more, and even more preferably 0.2% by mass or more,
based on the total amount of the refrigerating machine oil. In view
of improved lubricity, the content of an epoxy compound is
preferably 5.0% by mass or less, more preferably 3.0% by mass or
less, and even more preferably 2.0% by mass or less, based on the
total amount of the refrigerating machine oil.
[0112] The refrigerating machine oil may further include other
additives. Examples of the other additives include acid scavengers
other than epoxy compounds, antioxidants, extreme pressure agents,
oiliness agents, antifoaming agents, metal deactivators, antiwear
agents other than the compound represented by the formula (A),
viscosity index improvers, pour point depressants,
detergent-dispersants, and the like. The contents of these
additives may be 10% by mass or less or 5% by mass or less based on
the total amount of the refrigerating machine oil.
[0113] Among the aforementioned other additives, the refrigerating
machine oil preferably further includes at least one of an
antioxidant and an antiwear agent other than the compound
represented by the formula (A). The antioxidant may be a
phenol-based antioxidant such as 2,6-di-tert.-butyl-p-cresol and
bisphenol A or an amine-based antioxidant such as an
alkylphenyl-.alpha.-naphthylamine, and a dialkyldiphenylamine. The
antiwear agent other than the compound represented by the formula
(A) may be a phosphorus-based antiwear agent such as a phosphate
ester, an acid phosphate ester, a thiophosphate ester, an amine
salt of an acid phosphate ester, a chlorinated phosphate ester, and
a phosphite ester.
[0114] The kinematic viscosity at 40.degree. C. of the
refrigerating machine oil may be preferably 3 mm.sup.2/s or more,
more preferably 4 mm.sup.2/s or more, and even more preferably 5
mm.sup.2/s or more. The kinematic viscosity at 40.degree. C. of the
refrigerating machine oil may be preferably 500 mm.sup.2/s or less,
more preferably 400 mm.sup.2/s or less, and even more preferably
300 mm.sup.2/s or less.
[0115] The kinematic viscosity at 100.degree. C. of the
refrigerating machine oil may be preferably 1 mm.sup.2/s or more,
and more preferably 2 mm.sup.2/s or more. The kinematic viscosity
at 100.degree. C. of the refrigerating machine oil may be 100
mm.sup.2/s or less, and more preferably 50 mm.sup.2/s or less.
[0116] The pour point of the refrigerating machine oil may be
preferably -10.degree. C. or less, and more preferably -20.degree.
C. or less. The pour point in the present invention is measured in
accordance with JIS K2269-1987.
[0117] The volume resistivity of the refrigerating machine oil may
be preferably 1.0.times.10.sup.9 .OMEGA.m or more, more preferably
1.0.times.10.sup.10 .OMEGA.m or more, and even more preferably
1.0.times.10.sup.11 .OMEGA.m or more. The volume resistivity in the
present invention is measured at 25.degree. C. in accordance with
JIS C2101:1999.
[0118] The moisture content of the refrigerating machine oil may be
preferably 200 ppm or less based on the total amount of the
refrigerating machine oil, more preferably 100 ppm or less, and
even more preferably 50 ppm or less.
[0119] The acid value of the refrigerating machine oil may be 1.0
mg KOH/g or less, and more preferably 0.1 mg KOH/g or less. The
acid value in the present invention is measured in accordance with
JIS K2501:2003.
[0120] The ash content of the refrigerating machine oil may be
preferably 100 ppm or less, and more preferably 50 ppm or less. The
ash content in the present invention is measured in accordance with
JIS K2272:1998.
[0121] The refrigerating machine oil according to the present
embodiment is used with a refrigerant. Examples of the refrigerant
include saturated hydrofluorocarbon refrigerants, unsaturated
hydrofluorocarbon refrigerants, hydrocarbon refrigerants,
fluorine-containing ether-based refrigerants such as perfluoro
ethers, bis(trifluoromethyl)sulfide refrigerant,
trifluoroiodomethane refrigerant, and natural refrigerants such as
ammonia and carbon dioxide, and mixed refrigerants including one or
two or more of these refrigerants.
[0122] Examples of the saturated hydrofluorocarbon refrigerant
include saturated hydrofluorocarbons preferably having 1 to 3
carbon atoms, more preferably having 1 to 2 carbon atoms. Specific
examples include difluoromethane (R32), trifluoromethane (R23),
pentafluoroethane (R125), 1,1,2,2-tetrafluoroethane (R134),
1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a),
1,1-difluoroethane (R152a), fluoroethane (R161),
1,1,1,2,3,3,3-heptafluoropropane (R227ea),
1,1,1,2,3,3-hexafluoropropane (R236ea),
1,1,1,3,3,3-hexafluoropropane (R236fa),
1,1,1,3,3-pentafluoropropane (R245fa), 1,1,1,3,3-pentafluorobutane
(R365mfc), or mixtures of two or more of these.
[0123] The saturated hydrofluorocarbon refrigerant may be
appropriately selected from the followings, depending on uses and
required performances, but preferred examples include R32 alone;
R23 alone; R134a alone; R125 alone; a mixture of R134a/R32=60 to
80% by mass/40 to 20% by mass; a mixture of R32/R125=40 to 70% by
mass/60 to 30% by mass; a mixture of R125/R143a=40 to 60% by
mass/60 to 40% by mass; a mixture of R134a/R32/R125=60% by mass/30%
by mass/10% by mass; a mixture of R134a/R32/R125=40 to 70% by
mass/15 to 35% by mass/5 to 40% by mass; a mixture of
R125/R134a/R143a=35 to 55% by mass/1 to 15% by mass/40 to 60% by
mass, and the like. More specifically, the followings may be used:
a mixture of R134a/R32=70/30% by mass; a mixture of R32/R125=60/40%
by mass; a mixture of R32/R125=50/50% by mass (R410A); a mixture of
R32/R124=45/55% by mass (R410B); a mixture of R125/R143a=50/50% by
mass (R507C); a mixture of R32/R125/R134a=30/10/60% by mass; a
mixture of R32/R125/R134a=23/25/52% by mass (R407C); a mixture of
R32/R125/R134a=25/15/60% by mass (R407E); a mixture of R125/R134
a/R143a=44/4/52% by mass (R404A), and the like.
[0124] An unsaturated hydrofluorocarbon (HFO) refrigerant may be
preferably an unsaturated hydrofluorocarbon having 2 to 3 carbon
atoms, more preferably a fluoropropene, and even more preferably a
fluoropropene having 3 to 5 fluorine atoms. An unsaturated
hydrofluorocarbon refrigerant is preferably any one or a mixture of
two or more of 1,2,3,3,3-pentafluoropropene (HFO-1225ye),
1,3,3,3-tetrafluoropropane (HFO-1234ze), 2,3,3,3-tetrafluoropropane
(HFO-1234yf), 1,2,3,3-tetrafluoropropane (HFO-1234ye), and
3,3,3-trifluoropropene (HFO-1243zf). An unsaturated
hydrofluorocarbon refrigerant is preferably one or two or more
selected from HFO-1225ye, HFO-1234ze, and HFO-1234yf, in view of
physical properties as a refrigerant. An unsaturated
hydrofluorocarbon refrigerant may be a fluoroethylene, or more
preferably 1,1,2,3-trifluoroethylene (HFO-1123). An unsaturated
hydrofluorocarbon refrigerant may be
1-chloro-2,3,3,3-tetrafluoropropane (HCFO-1224yd), or may be any of
cis-1-chloro-2,3,3,3-tetrafluoropropane (HCFO-1224yd (Z)),
trans-1-chloro-2,3,3,3-tetrafluoropropane (HCFO-1224yd (E)), and
mixtures thereof.
[0125] The hydrocarbon refrigerant is preferably a hydrocarbon
having 1 to 5 carbon atoms, more preferably a hydrocarbon having 2
to 4 carbon atoms. Specifically, examples of the hydrocarbon
include methane, ethylene, ethane, propylene, propane (R290),
cyclopropane, normal butane, isobutane, cyclobutane,
methylcyclopropane, 2-methylbutane, normal pentane, or mixtures of
two or more of these. Among these, a hydrocarbon refrigerant in a
gaseous form at 25.degree. C. and 1 atmosphere is preferably used,
and propane, normal butane, isobutane, 2-methylbutane, or mixtures
thereof are more preferably used.
[0126] A refrigerant which can be used along with the refrigerating
machine oil according to the present embodiment may be a mixed
refrigerant including one or two or more refrigerants selected from
the aforementioned refrigerants, and for example, may be a mixed
refrigerant of one or two or more refrigerants selected from
unsaturated hydrocarbon (HFO) refrigerants and one or two or more
refrigerants selected from saturated hydrofluorocarbon (HFC)
refrigerants; or may be a mixed refrigerant in which one or two or
more refrigerants selected from hydrocarbon refrigerants and
natural refrigerants are further mixed with the above mixed
refrigerant. More Specifically, the refrigerant may be, for
example, a mixed refrigerant of one or two or more HFO refrigerants
selected from HFO-1225ye, HFO-1234ze, HFO-1234yf, HFO-1123,
HCFO-1224yd, and the like and one or two or more HFC refrigerants
selected from R32, R134a, R125, R152a, R227ea, R236fa, and the
like; or may be a mixed refrigerant in which a hydrocarbon
refrigerant such as R290 and R600a or a natural refrigerant such as
R744 is further mixed with the above mixed refrigerant.
[0127] The mixing ratio (mass ratio) of each refrigerant in these
mixed refrigerants may be HFO refrigerant/HFC
refrigerant/hydrocarbon refrigerant or natural refrigerant=5 to
95/95 to 5/0 to 20, preferably 15 to 85/85 to 15/0 to 10. More
specifically, these mixed refrigerants may be; but not limited to,
R444A, R445A, R446A, R447A, R447B, R448A, R449A, R449C, R452B,
R454B, R454C, R455A, R456A, R457A, R458A, R459A, R459B, R460B,
R461A, R513A, and the like.
[0128] The refrigerating machine oil according to the present
embodiment is usually present in a form of a working fluid
composition for a refrigerating machine in which it is mixed with a
refrigerant. That is, working fluid compositions for a
refrigerating machine according to the present embodiment may
include the aforementioned refrigerating machine oils and the
aforementioned refrigerants. The content of the refrigerating
machine oil in the working fluid composition for a refrigerating
machine may be preferably 1 to 500 parts by mass, and more
preferably 2 to 400 parts by mass, based on 100 parts by mass of
the refrigerant.
[0129] The refrigerating machine oils and the working fluid
compositions for a refrigerating machine according to the present
embodiment are suitably used in car air-conditioners with
reciprocating, rotary, or hermetic compressors; refrigerators; open
or closed car air-conditioners; dehumidifiers; water heaters;
freezers; fridge-freezer warehouse; automatic vending machines;
showcases; refrigerating machines in chemical plants; refrigerating
machines having centrifugal compressors; and the like.
Examples
[0130] Below, the present invention will be described in more
detail with reference to Examples, but the present invention shall
not be limited to these Examples.
[0131] In Examples and Comparative Examples, refrigerating machine
oils having the compositions (in "% by mass" based on the total
amount of a refrigerating machine oil) shown in Tables 1 to 3 were
prepared using the base oils and additives as described below.
(Base Oils)
[0132] Base oil 1: polyol ester (kinematic viscosity at 40.degree.
C.: 67.2 mm.sup.2/s, viscosity index: 84) of pentaerythritol and a
fatty-acid mixture of 2-methylpropanoic
acid/3,5,5-trimethylhexanoic acid (mass ratio: 35/65)
[0133] Base oil 2: complex ester (kinematic viscosity at 40.degree.
C.: 68.2 mm.sup.2/s, viscosity index: 144) obtained by reacting
neopentyl glycol (1 mol) and 1,4-butanediol (0.3 mol) with adipic
acid (2.4 mol) to produce an ester intermediate, further reacting
the ester intermediate with 2-ethylhexanol (2.4 mol), and removing
residual unreacted materials by distillation
[0134] Base oil 3: polyethyl vinyl ether (number average molecular
weight: 1900, kinematic viscosity at 40.degree. C.: 71.0
mm.sup.2/s, kinematic viscosity at 100.degree. C.: 8.6 mm.sup.2/s,
viscosity index: 89)
[0135] Base oil 4: polyol ester (kinematic viscosity at 40.degree.
C.: 68 mm.sup.2/s) of pentaerythritol and a fatty-acid mixture of
2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid (mass ratio:
50/50)
[0136] Base oil 5: complex ester (kinematic viscosity at 40.degree.
C.: 150 mm.sup.2/s) obtained by reacting neopentyl glycol (1 mol)
and 1,4-butanediol (0.3 mol) with adipic acid (2.4 mol) to produce
an ester intermediate, further reacting the ester intermediate with
3,5,5-trimethylhexanol (2.4 mol), and removing residual unreacted
materials by distillation
[0137] Base oil 6: polyol ester (kinematic viscosity at 40.degree.
C.: 220 mm.sup.2/s) of dipentaerythritol and a fatty-acid mixture
of 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid (mass ratio:
50/50).
[0138] Base oil 7: polyol ester (kinematic viscosity at 40.degree.
C.: 68 mm.sup.2/s) of pentaerythritol and a fatty-acid mixture of
pentanoic acid/3,5,5-trimethylhexanoic acid (mass ratio: 25/75)
[0139] Base oil 8: polypropylene glycol dimethyl ether (number
average molecular weight (Mn): 1000, kinematic viscosity at
40.degree. C.: 46.0 mm.sup.2/s, and viscosity index: 190)
(Additives)
[0140] A1: compound represented by the following formula
(A-1-1):
##STR00018##
[0141] A2: compound represented by the following formula
(A-1-2):
##STR00019##
[0142] A3: compound represented by the following formula
(A-1-3):
##STR00020##
[0143] a1: tricresyl phosphate
[0144] a2: di(n-octyl) acid phosphate
[0145] B1: glycidyl neodecanoate
[0146] B2: 2-ethylhexyl glycidyl ether
[0147] The antiwear property test was performed as described below
for each of the refrigerating machine oils of Examples and
Comparative Examples. Results are shown in Tables 1 to 3.
[0148] (Antiwear Property Test)
[0149] The antiwear property test was performed in accordance with
the Four-Ball Extreme Pressure test. The test was performed using
SUJ-2 as a rigid ball under the following conditions: test oil: 20
mL, test temperature: 80.degree. C., rotation rate: 1200 rpm,
applied load: 294 N, and testing time: 30 minutes. The antiwear
property was evaluated based on the average value of wear-track
diameters (mm) of fixed balls.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4
Example 5 Example 6 Composition Base oil 1 Remainder Remainder
Remainder Remainder -- -- Base oil 2 -- -- -- -- Remainder -- Base
oil 3 -- -- -- -- -- Remainder A1 0.05 -- -- -- 0.05 0.05 A2 --
0.02 0.5 -- -- -- A3 -- -- -- 0.5 -- -- a1 -- -- -- -- -- 1
Antiwear Wear-track 0.57 0.61 0.55 0.62 0.46 0.62 property diameter
(mm)
TABLE-US-00002 TABLE 2 Comparative Comparative Comparative
Comparative Example 1 Example 2 Example 3 Example 4 Composition
Base oil 1 Remainder Remainder -- -- Base oil 2 -- -- Remainder --
Base oil 3 -- -- Remainder A1 -- -- -- -- A2 -- -- -- -- A3 -- --
-- -- a1 -- 1 1 1 Antiwear wear-track 0.85 0.8 0.65 0.72 property
diameter (mm)
TABLE-US-00003 TABLE 3 Comparative Comparative Example 7 Example 8
Example 9 Example 5 Example 6 Composition Base oil 1 Remainder
Remainder Remainder Remainder Remainder A1 -- -- -- -- -- A2 0.05
0.05 0.05 -- -- A3 -- -- -- -- -- a1 -- -- -- 0.05 0.05 B1 0.5 1 --
0.5 1 B2 -- -- 1 -- -- Antiwear wear-track 0.56 0.55 0.57 0.87 0.88
property diameter (mm)
[0150] Refrigerating machine oils of Examples 10 to 16 were also
prepared as in Example 8 except that the following base oils were
used respectively instead of the base oil 1. These refrigerating
machine oils were evaluated for their antiwear property in a
similar way as described above, and showed the effect equivalent to
those of Examples 1 to 9.
[0151] (Example 10) base oil 4
[0152] (Example 11) base oil mixture of Base oil 1: Base oil
4=60:40 (mass ratio)
[0153] (Example 12) mixed base oil of Base oil 1: Base oil 5=80:20
(mass ratio)
[0154] (Example 13) mixed base oil of Base oil 4: Base oil 5=80:20
(mass ratio)
[0155] (Example 14) mixed base oil of Base oil 4: Base oil 6=80:20
(mass ratio)
[0156] (Example 15) base oil 7
[0157] (Example 16) base oil 8
[0158] Further, 1% by mass of tricresyl phosphate as an
orthophosphate and 0.5% by mass of 2,6-di-tert.-butyl-p-cresol
(DBPC) as an antioxidant were added to each of the refrigerating
machine oils from Examples 8 and 10 to 16 to prepare refrigerating
machine oils of Examples 17 to 24, respectively. These
refrigerating machine oils were evaluated for their antiwear
property in a similar way as described above, and showed the effect
equivalent to those of Examples 1 to 9.
[0159] The stability test was performed as described below for
Examples 7 to 9 and Comparative Examples 5 and 6. Results are shown
in Table 4.
[0160] (Stability Test)
[0161] Stability in a mixture with a refrigerant was evaluated in
accordance with JIS K2211:2009 (autoclave test). That is, 30 g of a
refrigerating machine oil adjusted to have a moisture content of
1000 ppm was weighed out into an autoclave along with catalyst
(wires of iron, copper, and aluminum, each having an outer diameter
of 1.6 mm and a length of 50 mm) and 30 g of R32. Subsequently, the
autoclave was sealed and heated at a temperature of 175.degree. C.
for 168 hours. Refrigerating machine oils after the tests were each
measured for their acid values (post-test acid value) in accordance
with JIS K2501:2003.
TABLE-US-00004 TABLE 4 Comparative Comparative Example 7 Example 8
Example 9 Example 5 Example 6 Stability Acid value 0.76 0.16 0.23
1.71 0.40 (mg KOH/g)
[0162] Further, stability was evaluated for the refrigerating
machine oils of Examples 10 to 24 in a similar way as described
above, and showed the effect equivalent to those of Examples 7 to
9. In addition, for Examples 17 to 24, stability was also evaluated
as in the above stability test except that HFO-1234yf was used as a
refrigerant instead of R32. Results showed that they have good
stability.
[0163] Hereinbefore, it should be understood that the present
invention shall not be limited to the embodiments and Examples
disclosed in the present description, and modifications may
appropriately be made without departing from the spirit and scope
of the present invention which can be understood from the claims
and the entire description. Therefor, it should be understood that
refrigerating machine oils with these modifications also fall
within the technical scope of the present invention.
* * * * *