U.S. patent application number 16/063872 was filed with the patent office on 2019-01-03 for refrigeration oil, and composition for use in refrigerating machine.
This patent application is currently assigned to IDEMITSU KOSAN CO., LTD.. The applicant listed for this patent is IDEMITSU KOSAN CO., LTD.. Invention is credited to Tomoya MATSUMOTO.
Application Number | 20190002792 16/063872 |
Document ID | / |
Family ID | 59311331 |
Filed Date | 2019-01-03 |
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United States Patent
Application |
20190002792 |
Kind Code |
A1 |
MATSUMOTO; Tomoya |
January 3, 2019 |
REFRIGERATION OIL, AND COMPOSITION FOR USE IN REFRIGERATING
MACHINE
Abstract
A refrigerator oil according to one embodiment of the present
invention contains: a base oil containing an oxygen-containing
organic compound; a polyphosphate ester compound; and a metal salt
of an organic carboxylic acid having 6 to 60 carbon atoms.
Inventors: |
MATSUMOTO; Tomoya;
(Funabashi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDEMITSU KOSAN CO., LTD. |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
IDEMITSU KOSAN CO., LTD.
Chiyoda-ku
JP
|
Family ID: |
59311331 |
Appl. No.: |
16/063872 |
Filed: |
January 13, 2017 |
PCT Filed: |
January 13, 2017 |
PCT NO: |
PCT/JP2017/001045 |
371 Date: |
June 19, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2207/129 20130101;
C10M 169/04 20130101; C10M 2207/026 20130101; C10M 129/93 20130101;
C10M 105/38 20130101; C10M 2207/125 20130101; C10M 2223/041
20130101; C10N 2020/101 20200501; C10M 2209/1033 20130101; C10M
2223/04 20130101; C10N 2030/02 20130101; C10M 129/40 20130101; C10M
107/24 20130101; C10M 2209/043 20130101; C10N 2030/06 20130101;
C10M 171/008 20130101; C10M 2225/00 20130101; C10M 2207/2835
20130101; C10M 2209/108 20130101; C10N 2020/105 20200501; C10N
2020/106 20200501; C10M 2209/1055 20130101; C10N 2020/103 20200501;
C10M 2207/126 20130101; C10N 2020/097 20200501; C10N 2040/30
20130101; C10M 2207/10 20130101; C10M 137/04 20130101; C10M 153/00
20130101; C10M 2207/04 20130101; C10M 2207/125 20130101; C10N
2010/02 20130101; C10M 2209/043 20130101; C10M 2209/1065 20130101;
C10M 2207/125 20130101; C10N 2010/02 20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04; C10M 137/04 20060101 C10M137/04; C10M 105/38 20060101
C10M105/38; C10M 107/24 20060101 C10M107/24; C10M 129/40 20060101
C10M129/40; C10M 129/93 20060101 C10M129/93; C10M 153/00 20060101
C10M153/00; C10M 171/00 20060101 C10M171/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 15, 2016 |
JP |
2016-006597 |
Claims
1: A refrigerator oil, comprising: a base oil comprising an
oxygen-containing organic compound; a polyphosphate ester compound;
and a metal salt of an organic carboxylic acid having 6 to 60
carbon atoms.
2: The refrigerator oil according to claim 1, wherein a content of
the polyphosphate ester compound is from 0.01 to 5.0% by mass based
on the total amount of the refrigerator oil.
3: The refrigerator oil according to claim 1, wherein a content of
the metal salt of an organic carboxylic acid is 1 ppm or more in
terms of metal concentration based on the total amount of the
refrigerator oil.
4: The refrigerator oil according to claim 1, wherein the
oxygen-containing organic compound is at least one selected from
the group consisting of a polyvinyl ether compound, a
polyoxyalkylene glycol compound, a copolymer of a poly(oxy)alkylene
glycol or a monoether thereof and a polyvinyl ether, and a polyol
ester compound.
5: The refrigerator oil according to claim 1, wherein: the
polyphosphate ester compound is a compound represented by the
following general formula (1): ##STR00014## n represents an integer
of from 1 to 10; R.sup.1 to R.sup.8 each independently represent a
hydrogen atom or an alkyl group having 1 to 20 carbon atoms; and
R.sup.9 represents a divalent hydrocarbon group having 2 to 20
carbon atoms.
6: The refrigerator oil according to claim 5, wherein in the
general formula (1) R.sup.9 comprises an arylene group.
7. The refrigerator oil according to claim 5, wherein in the
general formula (1), R.sup.9 represents a group represented by the
general formula (2) or (3): ##STR00015##
8: The refrigerator oil according to claim 1, wherein the
polyphosphate ester compound is at least one selected from the
group consisting of compounds represented by the following general
formulae (5) and (6): ##STR00016## wherein in the formula (5), n
represents an integer of from 1 to 10.
9: The refrigerator oil according to claim 1, wherein the metal
salt of an organic carboxylic acid is an alkali metal salt of an
organic carboxylic acid.
10: The refrigerator oil according to claim 1, wherein the metal
salt of an organic carboxylic acid is a metal salt of an organic
carboxylic acid having 16 to 20 carbon atoms.
11: The refrigerator oil according to claim 1, wherein the metal
salt of an organic carboxylic acid is potassium oleate.
12: A composition for a refrigerator, the composition comprising a
refrigerant and the refrigerator oil according to claim 1.
13: The composition for a refrigerator according to claim 12,
wherein the refrigerant is at least one selected from the group
consisting of a fluorinated hydrocarbon, carbon dioxide, a
hydrocarbon, and ammonia.
14: A method for producing a refrigerator oil, the method
comprising blending at least a polyphosphate ester compound and a
metal salt of an organic carboxylic acid having 6 to 60 carbon
atoms with a base oil containing an oxygen-containing organic
compound to obtain a refrigerator oil.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerator oil, and a
composition for a refrigerator using the refrigerator oil.
BACKGROUND ART
[0002] A refrigerator has a structure, in which a mixture of a
refrigerant and a refrigerator oil (which may be hereinafter
referred to as a "composition for a refrigerator") is circulated in
a closed system, and the refrigerator oil is demanded to have
compatibility with a refrigerant, stability, and lubricating
capability. For facilitating the satisfaction of these demanded
capabilities, a refrigerator oil containing an oxygen-containing
organic compound, such as a vinyl ether compound, as a major
component has been frequently used (see, for example, PTL 1).
[0003] A refrigerant used in recent years is becoming a
hydrofluorocarbon (HFC) instead of a hydrochlorofluorocarbon (HCFC)
having a high environmental load. In the HFC, a saturated
hydrofluorocarbon (saturated HFC), such as R32 (difluoroethane) and
R410A (a mixture of difluoroethane and pentafluoroethane), is
frequently used.
[0004] As a technique for improving the compatibility with the
saturated HFC refrigerant and the lubricating capability, such as
the wear resistance and the seize resistance, it has been known
that a phosphate ester compound having one phosphorus atom, such as
tricresyl phosphate (TCP), is added to a base oil containing an
oxygen-containing organic compound (see, for example, PTL 2).
[0005] For example, furthermore, PTLs 3 to 5 describe that a fatty
acid alkali metal salt is blended with a refrigerator oil for the
purpose of enhancing the wear resistance and the like. Moreover,
PTL 3 to 5 describe that a phosphate ester compound having one
phosphorus atom, such as TCP, is blended in addition to the fatty
acid alkali metal salt.
CITATION LIST
Patent Literatures
[0006] PTL 1: JP 6-128578 A
[0007] PTL 2: JP 10-130683 A
[0008] PTL 3: JP 2001-3072 A
[0009] PTL 4: JP 4-300996 A
[0010] PTL 5: WO 2008/041549
SUMMARY OF INVENTION
Technical Problem
[0011] There is an increasing demand of energy saving for various
refrigerators in recent years, and the enhancement of the
coefficient of performance (COP) is being demanded. Accordingly,
the refrigerator oil is demanded to achieve a lower coefficient of
friction in a sliding portion in a refrigerator for the enhancement
of the COP, in addition to the wear resistance.
[0012] However, as shown in PTLs 2 to 5, the lubricating oil
composition is difficult to decrease the coefficient of friction
sufficiently while improving the wear resistance in a sliding
portion of a refrigerator, by blending therewith a phosphate ester
compound having one phosphorus atom, such as TCP, a fatty acid
alkali metal salt, or both of them.
[0013] The present invention has been made in view of the
aforementioned problem, and an object thereof is to decrease the
coefficient of friction while improving the wear resistance in the
case where a refrigerator oil containing an oxygen-containing
organic compound as a base oil is used.
Solution to Problem
[0014] As a result of earnest investigations, the present inventors
have found that the problem can be solved by adding both a
particular phosphorus compound having two or more phosphorus atoms
in one molecule and an organic carboxylic acid metal salt to a base
oil containing an oxygen-containing organic compound, and thus the
present invention has been completed. The present invention
provides the refrigerator oil, the composition for a refrigerator,
and a method for producing a refrigerator oil shown below.
[0015] (1) A refrigerator oil containing: a base oil containing an
oxygen-containing organic compound; a polyphosphate ester compound;
and a metal salt of an organic carboxylic acid having 6 to 60
carbon atoms.
[0016] (2) A composition for a refrigerator, containing: a
refrigerant and the refrigerator oil according to the item (1).
[0017] (3) A method for producing a refrigerator oil, including
blending at least a polyphosphate ester compound and a metal salt
of an organic carboxylic acid having 6 to 60 carbon atoms with a
base oil containing an oxygen-containing organic compound to obtain
a refrigerator oil.
Advantageous Effects of Invention
[0018] According to the present invention, both a particular
phosphorus compound and a metal salt of an organic carboxylic acid
are added to a base oil, thereby providing a refrigerator oil that
is capable of decreasing the coefficient of friction while
improving the wear resistance.
DESCRIPTION OF EMBODIMENTS
[0019] The present invention will be described with reference to
embodiments below.
[0020] The refrigerator oil according to one embodiment of the
present invention contains a base oil, a polyphosphate ester
compound, and a metal salt of an organic carboxylic acid. The
components contained in the refrigerator oil will be described in
detail below.
[Base Oil]
[0021] The base oil in the present embodiment contains an
oxygen-containing organic compound. Examples of the
oxygen-containing organic compound include a synthetic oil
containing an ether group, a ketone group, an ester group, a
carbonate group, or the like in the molecule, and a synthetic oil
containing these groups and a hetero atom (such as a sulfur atom, a
fluorine atom, a chlorine atom, a silicon atom, and a nitrogen
atom). More specifically, examples thereof include a polyvinyl
ether compound (PVE), a polyoxyalkylene glycol compound (PAG), a
copolymer of a poly(oxy)alkylene glycol or a monoether thereof and
a polyvinyl ether (ECP), and a polyol ester compound (POE). The
oxygen-containing organic compound may be used solely or as a
combination of two or more kinds thereof.
[0022] Among these, one or more selected from a polyvinyl ether
compound (PVE) and a polyoxyalkylene glycol compound (PAG) is
preferred, and in particular, one or more selected from a polyvinyl
ether compound (PVE) is more preferred. The coefficient of friction
and the wear resistance can be readily improved in the case where
PVE is used with a polyphosphate ester compound represented by the
general formula (1), in which R.sup.9 represents a group
represented by the general formula (2), or a polyphosphate ester
compound represented by the general formula (5), which are
described later.
[0023] The oxygen-containing organic compound is a major component
of the refrigerator oil, and the oxygen-containing organic compound
is preferably contained in an amount of from 70 to 99.98% by mass,
more preferably from 90 to 99.5% by mass, and further preferably
from 93.0 to 99.3% by mass, based on the total amount of the
refrigerator oil.
[0024] PVE, PAG, ECP, and POE used as the base oil will be
described in more detail below.
<Polyvinyl Ether Compound (PVE)>
[0025] The polyvinyl ether compound (PVE) is a polymer having a
constituent unit derived from a vinyl ether, and specifically,
examples thereof include a polyvinyl compound having a constituent
unit represented by the following general formula (A-1).
##STR00001##
[0026] In the general formula (A-1), R.sup.1a, R.sup.2a, and
R.sup.3a each independently represent a hydrogen atom or a
hydrocarbon group having 1 to 8 carbon atoms, and may be the same
as or different from each other. Specific examples of the
hydrocarbon group include an alkyl group, such as a methyl group,
an ethyl group, an n-propyl group, an isopropyl group, an n-butyl
group, an isobutyl group, a sec-butyl group, a tert-butyl group,
pentyl groups of every kind, hexyl groups of every kind, heptyl
groups of every kind, and octyl groups of every kind; a cycloalkyl
group, such as a cyclopentyl group, a cyclohexyl group,
methylcyclohexyl groups of every kind, ethylcyclohexyl groups of
every kind, and dimethylcyclohexyl groups of every kind; an aryl
group, such as a phenyl group, methylphenyl groups of every kind,
ethylphenyl groups of every kind, and dimethylphenyl groups of
every kind; and an arylalkyl group, such as a benzyl group,
phenylethyl groups of every kind, and methylbenzyl groups of every
kind. Among those, an alkyl group is preferred.
[0027] R.sup.1a, R.sup.2a, and R.sup.3a each are more preferably a
hydrogen atom or an alkyl group having 3 or less carbon atoms, and
it is further preferred that all of them are hydrogen atoms. r in
the general formula (A-1) represents a repetition number, an
average value of which is in a range of from 0 to 10, and is more
preferably 0.
[0028] R.sup.4a represents a divalent hydrocarbon group having 2 to
10 carbon atoms. Specific examples of the divalent hydrocarbon
group having 2 to 10 carbon atoms include a divalent aliphatic
hydrocarbon group, such as an ethylene group, a phenylethylene
group, a 1,2-propylene group, a 2-phenyl-1,2-propylene group, a
1,3-propylene group, butylene groups of every kind, pentylene
groups of every kind, hexylene groups of every kind, heptylene
groups of every kind, octylene groups of every kind, nonylene
groups of every kind, and decylene groups of every kind; an
alicyclic hydrocarbon group having two bonding sites in an
alicyclic hydrocarbon, such as cyclohexane, methylcyclohexane,
ethylcyclohexane, dimethylcyclohexane, and propylcyclohexane; a
divalent aromatic hydrocarbon group, such as phenylene groups of
every kind, methylphenylene groups of every kind, ethylphenylene
groups of every kind, dimethylphenylene groups of every kind, and
naphthylene groups of every kind; an alkyl aromatic hydrocarbon
group having a monovalent bonding site in each of an alkyl group
moiety and an aromatic moiety of an alkyl aromatic hydrocarbon such
as toluene and ethylbenzene; and an alkyl aromatic hydrocarbon
group having bonding sites in an alkyl group moiety of a polyalkyl
aromatic hydrocarbon, such as xylene and diethylbenzene. Among
those, the aliphatic hydrocarbon group having 2 to 4 carbon atoms
is more preferred. The plural groups represented by R.sup.4aO may
be the same as or different from each other.
[0029] Furthermore, in the general formula (A-1), R.sup.5a
represents a hydrocarbon group having 1 to 10 carbon atoms.
Specific examples of the hydrocarbon group include an alkyl group,
such as a methyl group, an ethyl group, an n-propyl group, an
isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl
group, a tert-butyl group, pentyl groups of every kind, hexyl
groups of every kind, heptyl groups of every kind, octyl groups of
every kind, nonyl groups of every kind, and decyl groups of every
kind; a cycloalkyl group, such as a cyclopentyl group, a cyclohexyl
group, methylcyclohexyl groups of every kind, ethylcyclohexyl
groups of every kind, propylcyclohexyl groups of every kind, and
dimethylcyclohexyl groups of every kind; an aryl group, such as a
phenyl group, methylphenyl groups of every kind, ethylphenyl groups
of every kind, dimethylphenyl groups of every kind, propylphenyl
groups of every kind, trimethylphenyl groups of every kind,
butylphenyl groups of every kind, and naphthyl groups of every
kind; or an arylalkyl group, such as a benzyl group, phenylethyl
groups of every kind, methylbenzyl groups of every kind,
phenylpropyl groups of every kind, and phenylbutyl groups of every
kind. Among those, a hydrocarbon group having 1 to 8 carbon atoms
is preferred, and an alkyl group having 1 to 6 carbon atoms is more
preferred. The alkyl groups may be any of straight-chain, branched,
and cyclic groups.
[0030] In the polyvinyl compound having the constituent unit
represented by the general formula (A-1), a polymer or a copolymer
containing from 50 to 100% by mol of a constituent unit, in which
R.sup.1a, R.sup.2a, and R.sup.3a are all hydrogen atoms, r is 0,
and R.sup.5a is an ethyl group, and containing from 0 to 50% by mol
of a constituent unit, in which R.sup.1a, R.sup.2a, and R.sup.3a
are all hydrogen atoms, r is 0, and R.sup.5a is an alkyl group
having 3 or 4 carbon atoms, is preferred. It is more preferred that
the proportion of the constituent unit, in which R.sup.5a is an
ethyl group, is from 70 to 100% by mol, and the proportion of the
constituent unit, in which R.sup.5a is an alkyl group having 3 or 4
carbon atoms, is from 0 to 30% by mol, and it is further preferred
that the proportion of the former is from 80 to 95%, and the
proportion of the latter is from 5 to 20% by mol.
[0031] The alkyl group having 3 or 4 carbon atoms in R.sup.5a used
may be a n-propyl group, an isopropyl group, a n-butyl group, an
isobutyl group, a sec-butyl group, or a tert-butyl group, and an
isobutyl group is particularly preferred.
[0032] While the polyvinyl ether compound has the constituent unit
represented by the general formula (A-1), a repeating number
thereof may be appropriately selected according to a desired
kinematic viscosity. The polyvinyl ether compound can be produced
through polymerization of a corresponding vinyl ethereal monomer.
The vinyl ethereal monomer that can be used herein is represented
by the following general formula (A-2).
##STR00002##
[0033] In the formula (A-2), R.sup.1a, R.sup.2a, R.sup.3a,
R.sup.4a, R.sup.5a, and r have the same meanings as above.
[0034] As the vinyl ethereal monomer, there are various monomers
corresponding to the aforementioned polyvinyl ether compounds.
Examples thereof include vinyl methyl ether, vinyl ethyl ether,
vinyl-n-propyl ether, vinyl-isopropyl ether, vinyl-n-butyl ether,
vinyl-isobutyl ether, vinyl-sec-butyl ether, vinyl-tert-butyl
ether, vinyl-n-pentyl ether, vinyl-n-hexyl ether,
vinyl-2-methoxyethyl ether, vinyl-2-ethoxyethyl ether,
vinyl-2-methoxy-1-methylethyl ether, vinyl-2-methoxypropyl ether,
vinyl-3,6-dioxaheptyl ether, vinyl-3,6,9-trioxadecyl ether,
vinyl-1,4-dimethyl-3,6-dioxaheptyl ether,
vinyl-1,4,7-trimethyl-3,6,9-trioxadecyl ether,
vinyl-2,6-dioxa-4-heptyl ether, vinyl-2,6,9-trioxa-4-decyl ether,
1-methoxypropene, 1-ethoxypropene, 1-n-propoxypropene,
1-isopropoxypropene, 1-n-butoxypropene, 1-isobutoxypropene,
1-sec-butoxypropene, 1-tert-butoxypropene, 2-methoxypropene,
2-ethoxypropene, 2-n-propoxypropene, 2-isopropoxypropene,
2-n-butoxypropene, 2-isobutoxypropene, 2-sec-butoxypropene,
2-tert-butoxypropene, 1-methoxy-1-butene, 1-ethoxy-1-butene,
1-n-propoxy-1-butene, 1-isopropoxy-1-butene, 1-n-butoxy-1-butene,
1-isobutoxy-1-butene, 1-sec-butoxy-1-butene,
1-tert-butoxy-1-butene, 2-methoxy-1-butene, 2-ethoxy-1-butene,
2-n-propoxy-1-butene, 2-isopropoxy-1-butene, 2-n-butoxy-1-butene,
2-isobutoxy-1-butene, 2-sec-butoxy-1-butene,
2-tert-butoxy-1-butene, 2-methoxy-2-butene, 2-ethoxy-2-butene,
2-n-propoxy-2-butene, 2-isopropoxy-2-butene, 2-n-butoxy-2-butene,
2-isobutoxy-2-butene, 2-sec-butoxy-2-butene, and
2-tert-butoxy-2-butene. These vinyl ethereal monomers can be
produced by a known method.
[0035] In an end moiety of the polymer represented by the general
formula (A-1), a monovalent group derived from a saturated
hydrocarbon, an ether, an alcohol, a ketone, an amide, a nitrile,
or the like may be introduced by a known method.
[0036] In particular, as the polyvinyl ether compound, compounds
having an end structure of each of the following items (1) to (4)
are preferred.
[0037] (1) A compound, in which one end thereof is represented by
the following general formula (A-1-i), and the remaining end is
represented by the following general formula (A-1-ii)
##STR00003##
[0038] In the formula, R.sup.6a, R.sup.7a, and R.sup.8a each
independently represent a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms, and may be the same as or different
from each other; R.sup.9a represents a divalent hydrocarbon group
having 2 to 10 carbon atoms; R.sup.10a represents a hydrocarbon
group having 1 to 10 carbon atoms; r1 represents a number of from 0
to 10 in terms of average value thereof; and in the case where
plural groups represented by R.sup.9aO are present, the plural
groups represented by R.sup.9aO may be the same as or different
from each other.
##STR00004##
[0039] In the formula, R.sup.11a, R.sup.12a, and R.sup.13a each
independently represent a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms, and may be the same as or different
from each other; R.sup.14a represents a divalent hydrocarbon group
having 2 to 10 carbon atoms; R.sup.15a represents a hydrocarbon
group having 1 to 10 carbon atoms; r2 represents a number of from 0
to 10 in terms of average value thereof; and in the case where
plural groups represented by R.sup.14aO are present, the plural
groups represented by R.sup.14aO may be the same as or different
from each other.
[0040] (2) A compound, in which one end thereof is represented by
the foregoing general formula (A-1-i), and the remaining end is
represented by the following general formula (A-1-iii)
##STR00005##
[0041] In the formula, R.sup.16a, R.sup.17a, and R.sup.18a each
independently represent a hydrogen atom or a hydrocarbon group
having 1 to 8 carbon atoms, and may be the same as or different
from each other; R.sup.19a and R.sup.21a each independently
represent a divalent hydrocarbon group having 2 to 10 carbon atoms,
and may be the same as or different from each other; R.sup.20a and
R.sup.22a each independently represent a hydrocarbon group having 1
to 10 carbon atoms, and may be the same as or different from each
other; r3 and r4 each represent a number of from 0 to 10 in terms
of average value thereof, and may be the same as or different from
each other; in the case where plural groups represented by
R.sup.19aO are present, the plural groups represented by R.sup.19aO
may be the same as or different from each other; and in the case
where plural groups represented by R.sup.21aO are present, the
plural groups represented by R.sup.21aO may be the same as or
different from each other.
[0042] (3) A compound, in which one end thereof is represented by
the foregoing general formula (A-1-i), and the remaining end has an
olefinic unsaturated bond
[0043] (4) A compound, in which one end thereof is represented by
the foregoing general formula (A-1-i), and the remaining end is
represented by the following general formula (A-1-iv)
##STR00006##
[0044] In the formula, R.sup.23a, R.sup.24a, and R.sup.25a each
represent a hydrogen atom or a hydrocarbon group having 1 to 8
carbon atoms, and may be the same as or different from each
other.
[0045] The polyvinyl ether compound may also be a mixture of two or
more selected from those having an end structure of each of the
items (1) to (4). Preferred examples of the mixture include a
mixture of the compound having the end structure of the item (1)
and the compound having the end structure of the item (4); and a
mixture of the compound having the end structure of the item (2)
and the compound having the end structure of the item (3).
[0046] As for the polyvinyl ether compound, it is preferred to
select a degree of polymerization, an end structure, and the like,
so as to have a preferred viscosity range of the base oil described
later. The polyvinyl ether compound may be used solely or may be
used as a combination of two or more kinds thereof.
[0047] In the polyvinyl compound having the constituent unit
represented by the general formula (A-1), a compound, in which one
end thereof is presented by the general formula (A-1-i), and the
remaining end is represented by the general formula (A-1-ii) is
preferred.
[0048] Among these, it is more preferred that in the formulae
(A-1-i) and (A-1-ii), all of R.sup.6a, R.sup.7a, R.sup.8a,
R.sup.11a, R.sup.12a, and R.sup.13a are hydrogen atoms, all of r1
and r2 are 0, and R.sup.10a and R.sup.15a are each an alkyl group
having 1 to 4 carbon atoms.
<Polyoxyalkylene Glycol Compound (PAG)>
[0049] Examples of the polyoxyalkylene glycol compound (PAG)
include a compound represented by the following general formula
(B-1). In the case where PAG is contained in the base oil, the PAG
may be used either solely or as a combination of two or more kinds
thereof.
R.sup.1b--[(OR.sup.2b).sub.m--OR.sup.3b].sub.n (B-1)
[0050] In the formula, R.sup.1b represents a hydrogen atom, a
monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl
group having 2 to 10 carbon atoms, a hydrocarbon group having 2 to
6 bonding sites and having 1 to 10 carbon atoms, or an
oxygen-containing hydrocarbon group having 1 to 10 carbon atoms;
R.sup.2b represents an alkylene group having 2 to 4 carbon atoms;
R.sup.3b represents a hydrogen atom, a hydrocarbon group having 1
to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or
an oxygen-containing hydrocarbon group having 1 to 10 carbon atoms;
n represents an integer of 1 to 6; and m represents a number
providing of an average value of m.times.n of from 6 to 80.
[0051] In the general formula (B-1), the monovalent hydrocarbon
group having 1 to 10 carbon atoms in each of R.sup.1b and R.sup.3b
may be any of straight-chain, branched, and cyclic groups. The
hydrocarbon group is preferably an alkyl group, and specific
examples thereof include a methyl group, an ethyl group, an
n-propyl group, an isopropyl group, butyl groups of every kind,
pentyl groups of every kind, hexyl groups of every kind, heptyl
groups of every kind, octyl groups of every kind, nonyl groups of
every kind, decyl groups of every kind, a cyclopentyl group, and a
cyclohexyl group. As for the aforementioned monovalent hydrocarbon
group, when the number of carbon atoms is 10 or less, the
compatibility with a refrigerant becomes good. From such a
viewpoint, the number of carbon atoms of the monovalent hydrocarbon
group is more preferably from 1 to 4.
[0052] The hydrocarbon group moiety which the acyl group having 2
to 10 carbon atoms in each of R.sup.1b and R.sup.3b has may be any
of straight-chain, branched, and cyclic groups. The hydrocarbon
group moiety of the acyl group is preferably an alkyl group, and
specific examples thereof include those having 1 to 9 carbon atoms
among the alkyl groups that may be selected as the aforementioned
R.sup.1b and R.sup.3b. When the number of carbon atoms of the acyl
group is 10 or less, the compatibility with a refrigerant becomes
good. The number of carbon atoms of the acyl group is preferably
from 2 to 4.
[0053] In the case where all of R.sup.1b and R.sup.3b are a
hydrocarbon group or an acyl group, R.sup.1b and R.sup.3b may be
the same as or different from each other.
[0054] In the case where n is 2 or more, plural groups represented
by R.sup.3b in one molecule may be the same as or different from
each other.
[0055] In the case where R.sup.1b is the hydrocarbon group having 2
to 6 bonding sites and having 1 to 10 carbon atoms, the hydrocarbon
group may be either linear or cyclic. The hydrocarbon group having
2 bonding sites is preferably an aliphatic hydrocarbon group, and
examples thereof include an ethylene group, a propylene group, a
butylene group, a pentylene group, a hexylene group, a heptylene
group, an octylene group, a nonylene group, a decylene group, a
cyclopentylene group, and a cyclohexylene group. Examples of the
other hydrocarbon groups include residues resulting from removing a
hydroxyl group from a bisphenol compound such as bisphenol,
bisphenol F, and bisphenol A. The hydrocarbon group having 3 to 6
bonding sites is preferably an aliphatic hydrocarbon group, and
examples thereof include residues resulting from removing a
hydroxyl group from a polyhydric alcohol, such as
trimethylolpropane, glycerin, pentaerythritol, sorbitol,
1,2,3-trihydroxycyclohexane, and 1,3,5-trihydroxycyclohexane.
[0056] When the number of carbon atoms of the aliphatic hydrocarbon
group is 10 or less, the compatibility with a refrigerant becomes
good. The number of carbon atoms of the aliphatic hydrocarbon group
is preferably from 2 to 6.
[0057] Examples of the oxygen-containing hydrocarbon group having 1
to 10 carbon atoms in each of R.sup.1b and R.sup.3b include an
ether bond-containing linear or cyclic aliphatic group (for
example, a tetrahydrofurfuryl group).
[0058] At least one of R.sup.1b and R.sup.3b is preferably an alkyl
group, particularly preferably an alkyl group having 1 to 4 carbon
atoms.
[0059] R.sup.2b in the general formula (B-1) is an alkylene group
having 2 to 4 carbon atoms, and examples of the oxyalkylene group
as a repeating unit include an oxyethylene group, an oxypropylene
group, and an oxybutylene group. The oxyalkylene groups in one
molecule may be the same as each other, and two or more kinds of
oxyalkylene groups may also be contained. It is preferred that at
least an oxypropylene unit is contained in one molecule, and it is
more preferred that 50% by mol or more of an oxypropylene unit is
contained in the oxyalkylene unit.
[0060] In the general formula (B-1), n is an integer of from 1 to 6
and is determined according to the number of bonding sites of
R.sup.1b. For example, in the case where R.sup.1b is an alkyl group
or an acyl group, then n is 1; and in the case where R.sup.1b is an
aliphatic hydrocarbon group having 2, 3, 4, 5, or 6 bonding sites,
then n is 2, 3, 4, 5, or 6, respectively. m is a number providing
an average value of m.times.n of from 6 to 80. When the average
value is 80 or less, the compatibility with a refrigerant may be
improved. n is preferably an integer of from 1 to 3, and more
preferably 1. The average value of m.times.n is preferably
determined in such a manner that the viscosity of the base oil is
in the desired range described later. The polyoxyalkylene glycol
compound represented by the general formula (B-1) encompasses a
polyoxyalkylene glycol having a hydroxyl group at the end thereof,
which may be preferably used even though a hydroxyl group is
contained when the content of the hydroxyl group is 50% by mol or
less based on the whole end groups.
<Copolymer of Poly(Oxy)Alkylene Glycol or Monoether Thereof and
Polyvinyl Ether (ECP)>
[0061] In the refrigerator oil according to the present embodiment,
examples of the copolymer of a poly(oxy)alkylene glycol or a
monoether thereof and polyvinyl ether that can be used as the base
oil include a copolymer represented by the following general
formula (C-1) and a copolymer represented by the following general
formula (C-2) (hereinafter referred to as a "polyvinyl ether
copolymer I" and a "polyvinyl ether copolymer II", respectively).
The poly(oxy)alkylene glycol refers to both a polyalkylene glycol
and a polyoxyalkylene glycol.
##STR00007##
[0062] In the general formula (C-1), R.sup.1c, R.sup.2c, and
R.sup.3c each independently represent a hydrogen atom or a
hydrocarbon group having 1 to 8 carbon atoms, and may be the same
as or different from each other; R.sup.5c represents a divalent
hydrocarbon group having 2 to 4 carbon atoms; R.sup.6c represents
an aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon
atoms, an aromatic hydrocarbon group having 1 to 20 carbon atoms,
an acyl group having 2 to 20 carbon atoms, or an oxygen-containing
hydrocarbon group having 2 to 50 carbon atoms; R.sup.4c represents
a hydrocarbon group having 1 to 10 carbon atoms; and in the case
where plural groups represented by each of R.sup.1c to R.sup.6c are
present, the groups may be each the same as or different from each
other.
[0063] Specific examples of the hydrocarbon group having 1 to 8
carbon atoms in R.sup.1c to R.sup.3c include an alkyl group, such
as a methyl group, an ethyl group, an n-propyl group, an isopropyl
group, an n-butyl group, an isobutyl group, a sec-butyl group, a
tert-butyl group, pentyl groups of every kind, hexyl groups of
every kind, heptyl groups of every kind, and octyl groups of every
kind; a cycloalkyl group, such as a cyclopentyl group, a cyclohexyl
group, methylcyclohexyl groups of every kind, ethylcyclohexyl
groups of every kind, and dimethylcyclohexyl groups of every kind;
an aryl group, such as dimethylphenyl groups of every kind; or an
arylalkyl group, such as a benzyl group, phenylethyl groups of
every kind, and methylbenzyl groups of every kind. In particular,
R.sup.1c, R.sup.2c, and R.sup.3c are each preferably a hydrogen
atom.
[0064] Specific examples of the divalent hydrocarbon group having 2
to 4 carbon atoms represented by R.sup.5e include a divalent
alkylene group, such as a methylene group, an ethylene group,
propylene groups of every kind, and butylene group of every
kind.
[0065] In the general formula (C-1), v represents a repeating
number of R.sup.5cO, and is a number providing an average value
thereof of from 1 to 50, preferably from 1 to 20, more preferably
from 1 to 10, and further preferably from 1 to 5. In the case where
plural groups represented by R.sup.5cO are present, the plural
groups represented by R.sup.5cO may be the same as or different
from each other. v may be the same as or different from each other
in every constituent unit.
[0066] w represents a number of from 1 to 50, preferably from 1 to
10, more preferably from 1 to 2, and further preferably 1; u
represents a number of from 0 to 50, preferably from 2 to 25, and
more preferably from 6 to 15; and in the case where plural numbers
represented by each of w and u are present, the numbers may provide
either a block form or a random form.
[0067] In the general formula (C-1), R.sup.6c preferably represents
an alkyl group having 1 to 10 carbon atoms, an acyl group having 2
to 10 carbon atoms, or an oxygen-containing hydrocarbon group
having 2 to 50 carbon atoms.
[0068] Specific examples of the alkyl group having 1 to 10 carbon
atoms include a methyl group, an ethyl group, an n-propyl group, an
isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl
group, a tert-butyl group, pentyl groups of every kind, hexyl
groups of every kind, heptyl groups of every kind, octyl groups of
every kind, nonyl groups of every kind, decyl groups of every kind,
a cyclopentyl group, a cyclohexyl group, methylcyclohexyl groups of
every kind, ethylcyclohexyl groups of every kind, propylcyclohexyl
groups of every kind, and dimethylcyclohexyl groups of every
kind.
[0069] Examples of the acyl group having 2 to 10 carbon atoms
include an acetyl group, a propionyl group, a butyryl group, an
isobutyryl group, a valeryl group, an isovaleryl group, a pivaloyl
group, a benzoyl group, and a toluoyl group.
[0070] Preferred examples the oxygen-containing hydrocarbon group
having 2 to 50 carbon atoms include a methoxymethyl group, a
methoxyethyl group, a methoxypropyl group, a 1,1-bismethoxypropyl
group, a 1,2-bismethoxypropyl group, an ethoxypropyl group, a
(2-methoxyethoxy)propyl group, and a (1-methyl-2-methoxy)propyl
group.
[0071] In the general formula (C-1), specific examples of the
hydrocarbon group having 1 to 10 carbon atoms represented by
R.sup.4c include an alkyl group, such as a methyl group, an ethyl
group, an n-propyl group, an isopropyl group, an n-butyl group, an
isobutyl group, pentyl groups of every kind, hexyl groups of every
kind, heptyl groups of every kind, octyl groups of every kind,
nonyl groups of every kind, and decyl groups of every kind; a
cycloalkyl group, such as a cyclopentyl group, a cyclohexyl group,
methylcyclohexyl groups of every kind, ethylcyclohexyl groups of
every kind, propylcyclohexyl groups of every kind, and
dimethylcyclohexyl groups of every kind; an aryl group, such as a
phenyl group, methylphenyl groups of every kind, ethylphenyl groups
of every kind, dimethylphenyl groups of every kind, propylphenyl
groups of every kind, trimethylphenyl groups of every kind,
butylphenyl groups of every kind, and naphthyl groups of every
kind; and an arylalkyl group, such as a benzyl group, phenylethyl
groups of every kind, methylbenzyl groups of every kind,
phenylpropyl groups of every kind, and phenylbutyl groups of every
kind.
[0072] The polyvinyl ether copolymer I having the constituent unit
represented by the general formula (C-1) is capable of improving
the lubricating properties, the insulating properties, the
hygroscopicity, and the like, while satisfying the compatibility,
through formation of the copolymer.
[0073] In the polyvinyl ether copolymer II represented by the
general formula (C-2), R.sup.1c to R.sup.5c and v are the same as
those mentioned above. In the case where plural groups represented
by each of R.sup.4c and R.sup.5c are present, the groups may be
each the same as or different from each other. x and y each
represent a number of from 1 to 50, and in the case where plural
numbers represented by each of x and y are present, the numbers may
provide either a block form or a random form. X.sup.c and Y.sup.c
each independently represent a hydrogen atom, a hydroxyl group, or
a hydrocarbon group having 1 to 20 carbon atoms.
[0074] It is preferred that the repeating numbers u, w, x, and y in
the general formulae (C-1) and (C-2) are properly selected in such
a manner that a desired viscosity described later is obtained. The
production method of each of the polyvinyl ether copolymers I and
II is not particularly limited, as far as the method can provide
the polyvinyl ether copolymers I and II.
[0075] The vinyl ethereal copolymer I represented by the general
formula (C-1) can be formed into a polyvinyl ether copolymer I
having a structure, in which one end thereof is represented by the
following general formula (C-3) or (C-4), and the remaining end is
represented by the following general formula (C-5) or (C-6).
##STR00008##
[0076] In the aforementioned (C-3) and (C-4), R.sup.1c to R.sup.6c
and v are the same as those as mentioned above.
##STR00009##
[0077] In the aforementioned (C-5) and (C-6), R.sup.1c to R.sup.6c
and v are the same as those as mentioned above.
<Polyol Ester Compound (POE)>
[0078] In the refrigerator oil, as the polyol ester compound that
can be used as the base oil, an ester of a diol or a polyol having
3 to 20 hydroxyl groups and a fatty acid having 1 to 24 carbon
atoms is preferably used. Examples of the diol include ethylene
glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol,
1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol,
neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol,
1,7-heptanediol, 2-methyl-2-propyl-1,3-propanediol,
2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol,
1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol. Examples
of the polyol include a polyhydric alcohol, such as
trimethylolethane, trimethylolpropane, trimethylolbutane,
di(trimethylolpropane), tri(trimethylolpropane), pentaerythritol,
di(pentaerythritol), tri(pentaerythritol), glycerin, a polyglycerin
(e.g., dimer to icosamer of glycerin), 1,3,5-pentanetriol,
sorbitol, sorbitan, a sorbitol glycerin condensate, adonitol,
arabitol, xylitol, and mannitol; a saccharide, such as xylose,
arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose,
sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose,
raffinose, gentianose, and merenditose; a partially etherified
product thereof, and a methyl glucoside (a glucoside). Among these,
hindered alcohols, such as neopentyl glycol, trimethylolethane,
trimethylolpropane, trimethylolbutane, di(trimethylolpropane),
tri(trimethylolpropane), pentaerythritol, di(pentaerythritol), and
tri(pentaerythritol), are preferred as the polyol.
[0079] The fatty acid used may be a fatty acid having 1 to 24
carbon atoms while the number of carbon atoms thereof is not
particularly limited. In the fatty acid having 1 to 24 carbon
atoms, a fatty acid having 3 or more carbon atoms is preferred, a
fatty acid having 4 or more carbon atoms is more preferred, and a
fatty acid having 5 or more carbon atoms is further preferred, from
standpoint of the lubricating properties. A fatty acid having 18 or
less carbon atoms is preferred, a fatty acid having 12 or less
carbon atoms is more preferred, and a fatty acid having 9 or less
carbon atoms is further preferred, from the standpoint of the
compatibility with a refrigerant.
[0080] The fatty acid may be any of a straight-chain fatty acid and
a branched fatty acid, a straight-chain fatty acid is preferred
from the standpoint of the lubricating properties, and a branched
fatty acid is preferred from the standpoint of the hydrolysis
stability. Furthermore, the fatty acid may be any of a saturated
fatty acid and an unsaturated fatty acid.
[0081] Examples of the fatty acid include a straight-chain or
branched fatty acid, such as isobutyric 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, oleic acid; and a so-called neo acid, in which an
.alpha.-carbon atom is quaternary. More specifically, isobutyric
acid, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic
acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic
acid), pelargonic acid (n-nonanoic acid), capric acid (n-decanoic
acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid
(3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and the
like are preferred.
[0082] The polyol ester may be a partial ester, in which some of
the hydroxyl groups of a polyol remain without being esterified,
may be a complete ester, in which all of the hydroxyl groups of the
polyol are esterified, or may be a mixture of the partial ester and
the complete ester, but the polyol ester is preferably the complete
ester.
[0083] Among the polyol esters, due to the excellent hydrolysis
stability, esters of a hindered alcohol, such as neopentyl glycol,
trimethylolethane, trimethylolpropane, trimethylolbutane,
di(trimethylolpropane), tri(trimethylolpropane), pentaerythritol,
di(pentaerythritol), and tri(pentaerythritol), are preferred,
esters of neopentyl glycol, trimethylolethane, trimethylolpropane,
trimethylolbutane, and pentaerythritol are more preferred, and
esters of pentaerythritol are most preferred since they are
particularly excellent in compatibility with a refrigerant and
hydrolysis stability.
[0084] Specific examples of the preferred polyol ester include a
diester of neopentyl glycol and one or more fatty acids selected
from isobutyric acid, valeric acid, caproic acid, enanthic acid,
caprylic acid, pelargonic acid, capric acid, oleic acid,
isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid,
2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; a triester
of trimethylolethane and one or more fatty acids selected from
isobutyric acid, valeric acid, caproic acid, enanthic acid,
caprylic acid, pelargonic acid, capric acid, oleic acid,
isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid,
2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; a triester
of trimethylolpropane and one or more fatty acids selected from
isobutyric acid, valeric acid, caproic acid, enanthic acid,
caprylic acid, pelargonic acid, capric acid, oleic acid,
isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid,
2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; a triester
of trimethylolbutane and one or more fatty acids selected from
isobutyric acid, valeric acid, caproic acid, enanthic acid,
caprylic acid, pelargonic acid, capric acid, oleic acid,
isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid,
2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; and a
tetraester of pentaerythritol and one or more fatty acids selected
from isobutyric acid, valeric acid, caproic acid, enanthic acid,
caprylic acid, pelargonic acid, capric acid, oleic acid,
isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid,
2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid.
[0085] The ester of two or more fatty acids may be a mixture of two
or more esters of one fatty acid and a polyol, and an ester of a
mixed fatty acid of two or more kinds thereof and a polyol.
Particularly, an ester of a mixed fatty acid and a polyol is
excellent in low-temperature properties and compatibility with a
refrigerant.
[0086] The oxygen-containing organic compound contained in the
refrigerator oil preferably has a kinetic viscosity at 100.degree.
C. of from 1 to 30 mm.sup.2/s. When the kinetic viscosity is 1
mm.sup.2/s or more, a good lubricating capability can be exhibited,
and a good sealing property can be obtained. When the kinetic
viscosity is 30 mm.sup.2/s or less, a good compatibility may be
obtained between a refrigerant and the refrigerator oil, and good
energy saving property can be obtained. In this point of view, the
kinetic viscosity at 100.degree. C. of the oxygen-containing
organic compound is more preferably from 2 to 20 mm.sup.2/s, and
further preferably from 3 to 15 mm.sup.2/s.
[0087] The base oil may contain only the oxygen-containing organic
compound, and may also contain a mineral oil, a synthetic oil other
than the oxygen-containing organic compound, or both of them, in
addition to the oxygen-containing organic compound, unless the
object of the present invention is impaired. The amount of the base
oil other than the oxygen-containing organic compound is preferably
less than 10% by mass, more preferably less than 5% by mass, and
further preferably less than 1% by mass, based on the total amount
of the refrigerator oil. The base oil other than the
oxygen-containing organic compound preferably has a kinetic
viscosity at 100.degree. C. of from 1 to 30 mm.sup.2/s, more
preferably from 2 to 20 mm.sup.2/s, and further preferably from 3
to 15 mm.sup.2/s, as similar to the oxygen-containing organic
compound.
[Polyphosphate Ester Compound]
[0088] The polyphosphate ester compound contained in the
refrigerator oil according to the present embodiment is a phosphate
ester compound having at least two phosphoric acid skeletons in one
molecule. Specific examples of the polyphosphate ester compound
include a compound represented by the following general formula
(1).
##STR00010##
[0089] In the general formula (1), n represents an integer of from
1 to 10; R.sup.1 to R.sup.8 each independently represent a hydrogen
atom or an alkyl group having 1 to 20 carbon atoms; and R.sup.9
represents a divalent hydrocarbon group having 2 to 20 carbon
atoms.
[0090] The refrigerator oil according to the present embodiment can
decrease the coefficient of friction and can improve the wear
resistance, in a sliding portion of a refrigerator, by containing
the aforementioned polyphosphate ester compound and the organic
carboxylic acid metal salt described later.
[0091] The polyphosphate ester compound may be used solely or as a
combination of two or more kinds thereof.
[0092] In the general formula (1), the alkyl group in R.sup.1 to
R.sup.8 each may be any of straight-chain, branched, and cyclic
groups, and examples thereof include a methyl group, an ethyl
group, an n-propyl group, an isopropyl group, butyl groups of every
kind, pentyl groups of every kind, hexyl groups of every kind,
heptyl groups of every kind, octyl groups of every kind, nonyl
groups of every kind, decyl groups of every kind, undecyl groups of
every kind, dodecyl groups of every kind, tridecyl groups of every
kind, tetradecyl groups of every kind, pentadecyl groups of every
kind, hexadecyl groups of every kind, heptadecyl groups of every
kind, and octadecyl groups of every kind.
[0093] R.sup.1 to R.sup.8 each preferably represent a hydrogen atom
or an alkyl group having 1 to 4 carbon atoms, more preferably a
hydrogen atom or a methyl group, and most preferably a hydrogen
atom.
[0094] In the general formula (1), R.sup.9 preferably represents an
alkylene group, an arylene group, or a hydrocarbon group containing
an alkylene group and an arylene group, and preferably contains an
arylene group. In the case where R.sup.9 is an alkylene group,
examples of the alkylene group include an ethylene group, a
propylene group, a butylene group, a pentylene group, a hexylene
group, a heptylene group, an octylene group, a nonylene group, a
decylene group, an undecylene group, a dodecylene group, a
tetradecylene group, a hexadecylene group, an octadecylene group,
and an icosalene group, which each may be a straight-chain group,
or may be branched groups of every kind. The alkylene group may
also be a cyclic alkylene group, such as a cyclopropylene group, a
cyclobutylene group, a cyclopentylene group, a cyclohexylene group,
a cycloheptylene group, a cyclooctylene group, a dicyclopentylene
group, and a tricyclopentylene group.
[0095] The arylene group may be a substituted or unsubstituted
group, examples thereof include a substituted or unsubstituted
phenylene group, a substituted or unsubstituted naphthylene group,
and a substituted or unsubstituted biphenyl group, and the arylene
group is preferably unsubstituted. Among these, a phenylene group
is preferred.
[0096] In the case where R.sup.9 contains an arylene group and an
alkylene group, the arylene group may be the same as those
described above, and examples of the alkylene group include a
straight-chain, branched, or cyclic alkylene group having 1 to 14
carbon atoms, and a methylene group and the groups described above
can be used therefor. The alkylene group is preferably a
straight-chain or branched alkylene group having 1 to 5 carbon
atoms, specific examples thereof include a methylene group,
ethylene groups of every kind, such as 1,1-ethylene and
1,2-ethylene, propylene groups of every kind, such as
1,3-propylene, 1,2-propylene, and 2,2-propylene, butylene groups of
every kind, and pentylene groups of every kind, and among these a
2,2-propylene group (--C(CH.sub.3).sub.2--) is more preferred.
[0097] In the general formula (1), n is preferably from 1 to 8, and
the compound may be a single compound having only one kind of n, or
may be a mixture of compounds having two or more kinds of n. n is
more preferably from 1 to 3, and n is particularly preferably 1.
With a smaller value of n, a smaller molecular weight is obtained,
which can readily increase the solubility to the base oil, and
furthermore can readily decrease the coefficient of friction.
[0098] Specific preferred examples of the group represented by
R.sup.9 include groups represented by the following general
formulae (2) to (4), and the group is more preferably a group
represented by the general formula (2) or (3), and further
preferably a group represented by the general formula (2). The
group represented by the general formula (2) may be any of an
ortho-group, a meta-group, and a para-group, and is preferably a
meta-group.
##STR00011##
[0099] Specific examples of the preferred polyphosphate ester
compound include compounds represented by the following general
formulae (5) and (6). Among these, a compound represented by the
general formula (5) is preferred.
##STR00012##
[0100] In the formula (5), n represents an integer of from 1 to 10,
preferably from 1 to 8, and more preferably from 1 to 5. The
polyphosphate ester compound represented by the general formula (5)
readily exhibits the effect of improving the wear resistance and
decreasing the coefficient of friction in the case where the base
oil contains PVE as the oxygen-containing organic compound, and
readily exhibits the effect in the case where n is from 1 to 3, and
particularly in the case where n is 1.
##STR00013##
[0101] The content of the polyphosphate ester compound is
preferably from 0.01 to 5.0% by mass based on the total amount of
the refrigerator oil. In the present embodiment, by adding the
polyphosphate ester compound in an amount of 0.01% by mass or more,
the coefficient of friction in a sliding portion can be effectively
decreased while retaining the good stability and the good wear
resistance of the refrigerator oil. With the content thereof of
5.0% by mass or less, the polyphosphate ester compound can be
readily dissolved in the base oil, and readily exhibits the effect
corresponding to the content thereof.
[0102] For effectively decreasing the coefficient of friction in a
sliding portion while taking the stability and the wear resistance
of the refrigerator oil in consideration, the content of the
polyphosphate ester compound is more preferably from 0.5 to 5.0% by
mass, further preferably from 1.0 to 5.0% by mass, and particularly
preferably from 1.0 to 3.0% by mass.
[Organic Carboxylic Acid Metal Salt]
[0103] The organic carboxylic acid used in the organic carboxylic
acid metal salt in the present embodiment has from 6 to 60 carbon
atoms. The organic carboxylic acid is preferably an organic
carboxylic acid having 6 to 24 carbon atoms, and more preferably an
organic carboxylic acid having 16 to 20 carbon atoms.
[0104] Examples of the organic carboxylic acid include an aliphatic
saturated monocarboxylic acid, an aliphatic unsaturated
monocarboxylic acid, an aliphatic dicarboxylic acid, an aromatic
carboxylic acid, and an alicyclic carboxylic acid.
[0105] More specifically, examples of the aliphatic saturated
monocarboxylic acid include a straight-chain fatty acid, such as
caproic acid, caprylic acid, capric acid, lauric acid, myristic
acid, palmitic acid, stearic acid, arachic acid, cerotic acid, and
lacceroic acid; and a branched fatty acid, such as
2-methylpentanoic acid, 2,2-dimethylbutanoic acid, 2-methylhexanoic
acid, 5-methylhexanoic acid, 2,2-dimethylheptanoic acid,
2-ethyl-2-methyl-butanoic acid, 2-ethylhexanoic acid,
dimethylhexanoic acid, 2-n-propylpentanoic acid,
3,5,5-trimethylhexanoic acid, dimethyloctanoic acid, isotridecanoic
acid, isomyristic acid, isostearic acid, isoarachic acid, and
isohexanoic acid.
[0106] Examples of the aliphatic unsaturated monocarboxylic acid
include palmitoleic acid, oleic acid, elaidic acid, linoleic acid,
and linolenic acid, and also include an unsaturated hydroxy acid,
such as ricinoleic acid. Examples of the aliphatic dicarboxylic
acid include adipic acid, azelaic acid, and sebacic acid, and
examples of the aromatic carboxylic acid include benzoic acid,
phthalic acid, trimellitic acid, and pyromellitic acid. Examples of
the alicyclic carboxylic acid include naphthenic acid.
[0107] Dimer acids and trimer acids of these fatty acids may also
be used.
[0108] The organic carboxylic acid may be used solely or as a
combination of two or more kinds thereof.
[0109] Among these organic carboxylic acids, an aliphatic saturated
monocarboxylic acid having 16 to 20 carbon atoms and an aliphatic
unsaturated monocarboxylic acid having 16 to 20 carbon atoms are
preferred, and among these, an aliphatic unsaturated monocarboxylic
acid, such as oleic acid, is more preferred.
[0110] Specific examples of the metal constituting the organic
carboxylic acid metal salt include an alkali metal, such as
lithium, potassium, and sodium, an alkaline earth metal, such as
magnesium, calcium, and strontium, and other metals, such as zinc,
nickel, and aluminum. The metal is preferably an alkali metal or an
alkaline earth metal, more preferably an alkali metal, and
particularly preferably potassium. The metal may be used solely or
as a combination of two or more kinds thereof.
[0111] More preferred specific examples of the organic carboxylic
acid metal salt among the above include potassium oleate.
[0112] The content of the organic carboxylic acid metal salt in the
refrigerator oil is preferably 1 ppm or more in terms of metal
concentration based on the total amount (mass) of the refrigerator
oil. In the present embodiment, with the content thereof of 1 ppm
or more in terms of metal concentration, the coefficient of
friction can be decreased while improving the wear resistance by
using the aforementioned polyphosphate ester compound together. For
appropriately achieving the effect, the content of the organic
carboxylic acid metal salt is more preferably from 1 to 20 ppm,
further preferably from 1 to 10 ppm, and particularly preferably
from 1 to 5 ppm, in terms of metal concentration based on the total
amount of the refrigerator oil.
[0113] The blending method of the organic carboxylic acid metal
salt with the refrigerator oil may be any method, and it is
preferred that a solvent having the organic carboxylic acid metal
salt dissolved or dispersed therein in advance is blended with the
refrigerator oil. The method for providing the solvent having the
organic carboxylic acid metal salt dissolved or dispersed therein
is not particularly limited, and may be such a manner that an
organic carboxylic acid and a metal salt are reacted in a solvent,
and the organic carboxylic acid metal salt obtained through
reaction in advance may be dissolved or dispersed in a solvent.
[0114] The solvent may be one capable of dissolving or dispersing
the organic carboxylic acid metal salt, examples of which include
various alcohol compounds and various ether compounds. Among these,
a polyhydric alcohol, such as ethylene glycol, diethylene glycol,
triethylene glycol, tetraethylene glycol, propylene glycol,
dipropylene glycol, 1,4-butylene glycol 2,3-butylene glycol,
hexylene glycol, octylene glycol, and glycerin, is preferred, and
among these, dipropylene glycol is more preferred. The amount of
the solvent used is generally from 5 to 50 times the carboxylic
acid metal salt (mass).
[Additional Additive]
[0115] The refrigerator oil according to the present embodiment may
further contain one kind or two or more kinds selected from an
antioxidant, an acid scavenger, an anti-foaming agent, an extreme
pressure agent, an oiliness agent, an oxygen scavenger, a metal
deactivator, and a rust inhibitor, in addition to the
aforementioned polyphosphate ester compound and the aforementioned
organic carboxylic acid metal salt. Specifically, the refrigerator
oil may be formed of the base oil, the aforementioned polyphosphate
ester compound, and the aforementioned organic carboxylic acid
metal salt, may be formed of the base oil, the aforementioned
polyphosphate ester compound, the aforementioned organic carboxylic
acid metal salt, and the aforementioned solvent, may be formed of
the base oil, the aforementioned polyphosphate ester compound, the
aforementioned organic carboxylic acid metal salt, and an additive
other than these components, and may be formed of the
aforementioned polyphosphate ester compound, the aforementioned
organic carboxylic acid metal salt, the solvent, and an additive
other than these components. In this case, the base oil may contain
a mineral oil and a synthetic oil other than the aforementioned
oxygen-containing organic compound, in addition to the
oxygen-containing organic compound, and is preferably formed of the
oxygen-containing organic compound.
[0116] Among the aforementioned various additives, one kind or two
or more kinds of an antioxidant, an acid scavenger, and an
anti-foaming agent is preferably contained. The additive other than
the aforementioned polyphosphate ester compound and the
aforementioned organic carboxylic acid metal salt may be preferably
contained in an amount of 15% by mass or less, and more preferably
from 0 to 5% by mass based on the total amount of the refrigerator
oil.
[0117] Examples of the antioxidant include a phenol antioxidant,
such as 2,6-di-tert-butyl-4-methylphenol,
2,6-di-tert-butyl-4-ethylphenol, and
2,2'-methylenebis(4-methyl-6-tert-butylphenol), and an amine
antioxidant, such as phenyl-.alpha.-naphthylamine and
N,N'-di-phenyl-p-phenylenediamine, and a phenol antioxidant is
preferred. From the standpoints of the effects, the economic
efficiency, and the like, the content of the antioxidant is
generally from 0.01 to 5% by mass, and preferably from 0.05 to 3%
by mass, based on the total amount of the refrigerator oil.
[0118] Examples of the acid scavenger include an epoxy compound,
such as phenyl glycidyl ether, an alkyl glycidyl ether, an alkylene
glycol glycidyl ether, cyclohexene oxide, an .alpha.-olefin oxide,
and an epoxidized soybean oil. Among these, from the standpoint of
the compatibility, phenyl glycidyl ether, an alkyl glycidyl ether,
an alkylene glycol glycidyl ether, cyclohexene oxide, and an
.alpha.-olefin oxide are preferred.
[0119] The alkyl group in the alkyl glycidyl ether and the alkylene
group in the alkylene glycol glycidyl ether may be each branched,
and the number of carbon atoms thereof is generally from 3 to 30,
preferably from 4 to 24, and particularly preferably from 6 to 16.
As for the .alpha.-olefin oxide, one having a total number of
carbon atoms of generally from 4 to 50, preferably from 4 to 24,
and particularly from 6 to 16 may be used. In the present
embodiment, the acid scavenger may be used solely, or may be used
as a combination of two or more kinds thereof. The content thereof
is generally from 0.005 to 5% by mass, and preferably from 0.05 to
8% by mass, based on the total amount of the refrigerator oil, from
the standpoints of the effects and the inhibition of sludge
generation.
[0120] In the present embodiment, by containing the acid scavenger,
the stability of the refrigerator oil can be enhanced.
[0121] Examples of the anti-foaming agent include a silicone
anti-foaming agent and a fluorinated silicone anti-foaming agent.
The content of the anti-foaming agent is generally from 0.005 to 2%
by mass, and preferably from 0.01 to 1% by mass, based on the total
amount of the refrigerator oil.
[0122] Examples of the extreme pressure agent include a phosphorus
extreme pressure agent, such as a phosphate ester, an acidic
phosphate ester, a phosphite ester, an acidic phosphite ester, and
amine salts thereof.
[0123] These phosphorus extreme pressure agents each have one
phosphorus atom in the molecule thereof, and examples thereof
include tricresyl phosphate, trithiophenyl phosphate,
tri(nonylphenyl) phosphite, dioleyl hydrogenphosphite, and
2-ethylhexyldiphenyl phosphite.
[0124] Examples of the extreme pressure agent other than those
mentioned above include a sulfur-based extreme pressure agent, such
as sulfurized fats and oils, a sulfurized fatty acid, a sulfurized
ester, a sulfurized olefin, a dihydrocarbyl polysulfide, a
thiocarbamate compound, a thioterpene compound, and a dialkyl
thiodipropionate compound.
[0125] The content of the extreme pressure agent is generally from
0.001 to 5% by mass, and particularly preferably from 0.005 to 3%
by mass, based on the total amount of the refrigerator oil, from
the standpoints of the lubricating properties and the
stability.
[0126] The extreme pressure agent may be used solely or may be used
as a combination of two or more kinds thereof.
[0127] Examples of the oiliness agent include an aliphatic
saturated or unsaturated monocarboxylic acid, such as stearic acid
and oleic acid; a polymerized fatty acid, such as a dimer acid and
a hydrogenated dimer acid; a hydroxyfatty acid, such as ricinoleic
acid and 12-hydroxystearic acid; an aliphatic saturated or
unsaturated monoalcohol, such as lauryl alcohol and oleyl alcohol;
an aliphatic saturated or unsaturated monoamine, such as
stearylamine and oleylamine; an aliphatic saturated or unsaturated
monocarboxylic acid amide, such as lauric acid amide and oleic acid
amide; and a partial ester of a polyhydric alcohol, such as
glycerin and sorbitol, and an aliphatic saturated or unsaturated
monocarboxylic acid.
[0128] These compounds may be used solely, or may be used as a
combination of two or more kinds thereof. The content thereof is
generally selected from a range of from 0.01 to 10% by mass, and
preferably a range of from 0.1 to 5% by mass, based on the total
amount of the refrigerator oil.
[0129] Examples of the oxygen scavenger include a sulfur-containing
aromatic compound, such as 4,4'-thiobis(3-methyl-6-t-butylphenol),
diphenyl sulfide, dioctyldiphenyl sulfide, a dialkyldiphenylene
sulfide, benzothiophene, dibenzothiophene, phenothiazine,
benzothiapyrane, thiapyrane, thianthrene, dibenzothiapyrane, and
diphenylene disulfide; an aliphatic unsaturated compound, such as
various olefins, dienes, and trienes; and a terpene compound having
a double bond.
[0130] Examples of the metal deactivator include an
N--[N,N'-dialkyl(alkyl group having 3 to 12 carbon
atoms)aminomethyl]triazole.
[0131] Examples of the rust inhibitor include a metal sulfonate, an
aliphatic amine compound, an organic phosphite ester, an organic
phosphate ester, an organic sulfonic acid metal salt, an organic
phosphoric acid metal salt, an alkenyl succinate ester, and a
polyhydric alcohol ester.
[0132] The refrigerator oil according to the present embodiment may
further contain other various known additives in such a range that
does not impair the object of the present invention.
[Refrigerant]
[0133] The refrigerator oil according to the present embodiment is
used in combination with a refrigerant, and specifically is mixed
with a refrigerant and used in a refrigerator. In other words, in
the present embodiment, the refrigerator oil is used in a
refrigerator, in the form of a composition for a refrigerator
containing the refrigerator oil and a refrigerant. In the
composition for a refrigerator, the amounts of the refrigerant and
the refrigerator oil used are generally in a range of from 99/1 to
10/90, and preferably from 95/5 to 30/70, in terms of mass ratio
(refrigerant)/(lubricating oil). When the mass ratio is in the
range, the refrigeration capability of the refrigerator and the
lubrication capability can be made appropriate.
[0134] Examples of the refrigerant used include one kind or two or
more kinds selected from a fluorinated hydrocarbon and a natural
refrigerant, such as carbon dioxide, a hydrocarbon, and
ammonia.
<Fluorinated Hydrocarbon>
[0135] Examples of the fluorinated hydrocarbon include a saturated
fluorinated hydrocarbon compound (saturated HFC) and an unsaturated
fluorinated hydrocarbon compound (HFO).
[0136] The saturated fluorinated hydrocarbon compound is generally
a fluoride of an alkane having 1 to 4 carbon atoms, preferably a
fluoride of an alkane having 1 to 3 carbon atoms, and more
preferably a fluoride of an alkane having 1 to 2 carbon atoms
(methane or ethane). Specific examples of the fluoride of methane
or ethane include trifluoromethane (R23), difluoromethane (R32),
1,1-difluoroethane (R152a), 1,1,1-trifluoroethane (R143a),
1,1,2-trifluoroethane (R143), 1,1,1,2-tetrafluoroethane (R134a),
1,1,2,2-tetrafluoroethane (R134), and 1,1,1,2,2-pentafluoroethane
(R125). Among those, difluoromethane and
1,1,1,2,2-pentafluoroethane are preferred.
[0137] The saturated fluorinated hydrocarbon compound may be used
solely, or may be used as a combination of two or more kinds
thereof. Examples of the case using two or more kinds of saturated
fluorinated hydrocarbon compounds in combination include a mixed
refrigerant of two or more kinds of saturated fluorinated
hydrocarbon compounds having 1 to 3 carbon atoms; and a mixed
refrigerant of two or more kinds of saturated fluorinated
hydrocarbon compounds having 1 to 2 carbon atoms.
[0138] Specific examples of the mixed refrigerant include a mixture
of R32 and R125 (R410A), a mixture of R125, R143a, and R134a
(R404A), a mixture of R32, R125, and R134a (e.g., R407A, R407C, and
R407E), and a mixture of R125 and R143a (R507A).
[0139] Examples of the unsaturated fluorinated hydrocarbon compound
include those having a carbon-carbon double bond, such as a
fluoride of a linear olefin having 2 to 6 carbon atoms that is
straight-chain or branched, and a fluoride of a cyclic olefin
having 4 to 6 carbon atoms.
[0140] More specifically, examples thereof include an ethylene
having 1 to 3 fluorine atoms introduced thereinto, a propene having
1 to 5 fluorine atoms introduced thereinto, a butene having 1 to 7
fluorine atoms introduced thereinto, a pentene having 1 to 9
fluorine atoms introduced thereinto, a hexene having 1 to 11
fluorine atoms introduced thereinto, a cyclobutene having 1 to 5
fluorine atoms introduced thereinto, a cyclopentene having 1 to 7
fluorine atoms introduced thereinto, and a cyclohexene having 1 to
9 fluorine atoms introduced thereinto.
[0141] Among those unsaturated fluorinated hydrocarbon compounds, a
fluoride of propene is preferred, a propene having 3 to 5 fluorine
atoms introduced thereinto is more preferred, and a propene having
4 fluorine atoms introduced thereinto is most preferred. Specific
preferred examples thereof include 1,3,3,3-tetrafluoropropene
(HFO1234ze) and 2,3,3,3-tetrafluoropropene (HFO1234yf).
[0142] The unsaturated fluorinated hydrocarbon compound may be used
solely, or may be used as a combination of two or more kinds
thereof, or may be used in combination of a refrigerant other than
the unsaturated fluorinated hydrocarbon compound. Examples of the
case using a combination with a refrigerant other than the
unsaturated fluorinated hydrocarbon compound include a mixed
refrigerant of a saturated fluorinated hydrocarbon compound and an
unsaturated fluorinated hydrocarbon compound. Specific examples of
the mixed refrigerant include a mixed refrigerant of R-32,
HFO1234ze, and R152a (such as AC5, mixing ratio:
13.23/76.20/9.96).
<Natural Refrigerant>
[0143] Examples of the natural refrigerant include carbon dioxide
(carbonic acid gas), a hydrocarbon, such as propane, n-butane,
isobutane, 2-methylbutane, n-pentane, cyclopentane, isobutane, and
n-butane, and ammonia. The natural refrigerant may be used solely
or as a combination of two or more kinds thereof, and may be
combined with a refrigerant other than the natural refrigerant.
Examples of the case using the natural refrigerant in combination
with a refrigerant other than the natural refrigerant include mixed
refrigerants with a saturated fluorinated hydrocarbon compound,
with an unsaturated fluorinated hydrocarbon compound, and with both
of them. Specific examples of the mixed refrigerant include a mixed
refrigerant of carbon dioxide, HFO1234ze, and R134a (such as AC6,
mixing ratio: 5.15/79.02/15.41).
[0144] In the present embodiment, among these refrigerants, a
fluorinated hydrocarbon is preferred, and a saturated fluorinated
hydrocarbon is more preferred. The refrigerant may be a mixture of
the saturated fluorinated hydrocarbon and another refrigerant, and
is preferably formed only of the saturated fluorinated hydrocarbon.
Among them, R32, R125, and R410A, which is a mixture thereof, are
further preferred. The refrigerant particularly preferably contains
R32, and in this case, the proportion of R32 in the entire
refrigerant based on the total amount of the refrigerant is
preferably 50% by mass or more, more preferably 70% by mass or
more, and most preferably 100% by mass, i.e., a refrigerant
containing R32 solely.
[Refrigerator]
[0145] The refrigerator oil or composition for a refrigerator
according to the present embodiment is used by charging in an
interior of a refrigerator. The refrigerator herein has a
refrigeration cycle constituted by essential components including a
compressor, a condenser, an expansion mechanism (e.g., an expansion
valve), and an evaporator, or including a compressor, a condenser,
an expansion mechanism, a dryer, and an evaporator. The
refrigerator oil is used for lubricating, for example, a sliding
portion provided in a compressor.
[0146] The sliding portion of a refrigerator is preferably between
metals, and examples of the metal in the sliding portion include
iron and a steel material. The refrigerator oil of the present
embodiment can decrease the coefficient of friction while enhancing
the wear resistance between iron or steel materials.
[0147] More specifically, the refrigerator oil and the composition
for a refrigerator can be used, for example, for various
refrigerator systems, hot water systems, and heating systems, such
as a car air conditioner, a gas heat pump (GHP), an air
conditioner, a refrigeration chamber, an automatic vending machine,
a showcase, a hot water supply machine, and a floor heater.
[Production Method of Refrigerator Oil]
[0148] A method for producing a refrigerator oil according to one
embodiment of the present invention includes blending at least the
polyphosphate ester compound and the organic carboxylic acid metal
salt with the base oil containing an oxygen-containing organic
compound, so as to produce the refrigerator oil. In the method, one
kind or two or more kinds of the aforementioned additives may be
blended in addition to the polyphosphate ester compound and the
organic carboxylic acid metal salt. The detailed descriptions for
the base oil, the polyphosphate ester compound, the organic
carboxylic acid metal salt, and the additives may be the same as
described above, and are omitted herein.
EXAMPLES
[0149] The present invention will be described more specifically
with reference to examples below, but the present invention is not
limited to the examples. The properties of the base oil and the
characteristics of the refrigerator oil and the composition for a
refrigerator were obtained by the procedures shown below.
(1) Kinetic Viscosity
[0150] The kinematic viscosity was measured with a glass capillary
viscometer according to JIS K2283:2000.
(2) Lubricating Property Test
[0151] The coefficient of friction and the ring wear amount in a
sliding portion of each of the compositions for a refrigerator were
measured in an R32 (difluoromethane) refrigerant environment using
a sealing-type block-on-ring friction tester (LFW-1) under the
following conditions.
[0152] Ring: FC250
[0153] Block: SKH51
[0154] Number of revolutions: 1,000 rpm
[0155] Preconditioning: Load 300 N.times.1 minute
[0156] Load: 500 N
[0157] Time: 30 minutes
[0158] Oil temperature: 80.degree. C.
[0159] Refrigerant pressure: 0.4 MPa
Examples 1 to 14 and Comparative Examples 1 to 14
[0160] Refrigerator oils and compositions for a refrigerator using
the refrigerator oils of Examples and Comparative Examples shown in
Table 1 were prepared and subjected to the lubricating property
test. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 Base oil PVE 98.25
97.25 96.25 98.25 98.25 98.25 -- PAG -- -- -- -- -- -- 98.25 ECP --
-- -- -- -- -- -- POE -- -- -- -- -- -- -- Additive Polyphosphate
ester 1.00 2.00 3.00 -- -- -- 1.00 compound 1 Polyphosphate ester
-- -- -- 1.00 -- -- -- compound 2 Polyphosphate ester -- -- -- --
1.00 -- -- compound 3 Polyphosphate ester -- -- -- -- -- 1.00 --
compound 4 Diluted product of organic 0.05 0.05 0.05 0.06 0.05 0.05
0.05 carboxylic acid metal salt Antioxidant 0.30 0.30 0.30 0.30
0.30 0.30 0.30 Acid scavenger 0.30 0.30 0.30 0.30 0.30 0.30 0.30
Anti-foaming agent 0.10 0.10 0.10 0.10 0.10 0.10 0.10 (Total)
100.00 100.00 100.00 100.00 100.00 100.00 100.00 Metal
concentration (ppm) 2 2 2 2 2 2 2 (derived from organic carboxylic
acid metal salt) in refrigerator oil Lubricating Coefficient of
friction (--) 0.041 0.039 0.034 0.048 0.046 0.047 0.050 property
test Ring wear amount (mg) 0.2 0.1 0.1> 0.2 0.2 0.2 0.2 Example
8 9 10 11 12 13 14 Base oil PVE -- -- -- -- -- -- -- PAG 96.25
98.25 96.25 96.25 96.25 -- -- ECP -- -- -- -- -- 96.25 -- POE -- --
-- -- -- -- 96.25 Additive Polyphosphate ester 3.00 -- -- -- --
3.00 3.00 compound 1 Polyphosphate ester -- 1.00 3.00 -- -- -- --
compound 2 Polyphosphate ester -- -- -- 3.00 -- -- -- compound 3
Polyphosphate ester -- -- -- -- 3.00 -- -- compound 4 Diluted
product of organic 0.05 0.05 0.05 0.05 0.05 0.05 0.06 carboxylic
acid metal salt Antioxidant 0.30 0.30 0.30 0.30 0.30 0.30 0.30 Acid
scavenger 0.30 0.30 0.30 0.30 0.30 0.30 0.30 Anti-foaming agent
0.10 0.10 0.10 0.10 0.10 0.10 0.10 (Total) 100.00 100.00 100.00
100.00 100.00 100.00 100.00 Metal concentration (ppm) 2 2 2 2 2 2 2
(derived from organic carboxylic acid metal salt) in refrigerator
oil Lubricating Coefficient of friction (--) 0.048 0.050 0.047
0.046 0.045 0.051 0.050 property test Ring wear amount (mg) 0.1>
0.2 0.1> 0.1> 0.1> 0.1> 0.1> Comparative Example 1 2
3 4 5 6 7 Base oil PVE 99.30 98.30 97.30 96.30 98.30 98.30 98.30
PAG -- -- -- -- -- -- -- ECP -- -- -- -- -- -- -- POE -- -- -- --
-- -- -- Additive Polyphosphate ester -- 1.00 2.00 3.00 -- -- --
compound 1 Polyphosphate ester -- -- -- -- 1.00 -- -- compound 2
Polyphosphate ester -- -- -- -- -- 1.00 -- compound 3 Polyphosphate
ester -- -- -- -- -- -- 1.00 compound 4 Diluted product of organic
-- -- -- -- -- -- -- carboxylic acid metal salt Antioxidant 3.30
3.30 3.30 3.30 3.30 3.30 3.30 Acid scavenger 3.30 3.30 3.30 3.30
3.30 3.30 3.30 Anti-foaming agent 0.10 0.10 0.10 0.10 0.10 0.10
0.10 (Total) 100.00 100.00 100.00 100.0 100.00 100.00 100.00 Metal
concentration (ppm) 0 0 0 0 0 0 0 (derived from organic carboxylic
acid metal salt) in refrigerator oil Lubricating Coefficient of
friction (--) 0.073 0.060 0.057 0.053 0.069 0.065 0.062 property
test Ring wear amount (mg) 0.4 0.2 0.1 0.1> 0.1> 0.1>
0.1> Comparative Example 8 9 10 11 12 13 14 Base oil PVE 99.25
-- -- -- -- -- -- PAG -- 99.30 96.30 -- -- -- -- ECP -- -- -- 99.30
96.30 -- -- POE -- -- -- -- -- 99.30 96.30 Additive Polyphosphate
ester -- -- 3.00 -- 3.00 -- 3.00 compound 1 Polyphosphate ester --
-- -- -- -- -- -- compound 2 Polyphosphate ester -- -- -- -- -- --
-- compound 3 Polyphosphate ester -- -- -- -- -- -- -- compound 4
Diluted product of organic 0.05 -- -- -- -- -- -- carboxylic acid
metal salt Antioxidant 3.30 3.30 3.30 3.30 3.30 3.30 3.30 Acid
scavenger 3.30 3.30 3.30 3.30 3.30 3.30 3.30 Anti-foaming agent
0.10 0.10 0.10 0.10 0.10 0.10 0.10 (Total) 100.00 100.00 100.00
100.00 100.00 100.00 100.00 Metal concentration (ppm) 2 0 0 0 0 0 0
(derived from organic carboxylic acid metal salt) in refrigerator
oil Lubricating Coefficient of friction (--) 0.061 0.085 0.066
0.059 0.055 0.053 0.052 property test Ring wear amount (mg) 0.4
0.1> 0.1> 0.5 0.2 0.7 0.5
[0161] In Examples and Comparative Examples, the base oils and the
additives are as follows.
Base Oils
[0162] PVE: Copolymer of ethyl vinyl ether and isobutyl vinyl ether
(molar ratio: 9/1, kinetic viscosity at 100.degree. C.: 7.8
mm.sup.2/s), in which both ends are represented by the general
formula (A-1-i) and the general formula (A-1-ii) respectively,
R.sup.6a to R.sup.8a are hydrogen atoms, R.sup.11a to R.sup.13a are
hydrogen atoms, both r1 and r2 are 0, and R.sup.10a and R.sup.15a
each are an ethyl group or an isobutyl group
[0163] PAG: Polyoxypropylene glycol (kinetic viscosity at
100.degree. C.: 9.8 mm.sup.2/s)
[0164] ECP: Copolymer of polypropylene glycol (PPG) and polyethyl
vinyl ether (PEV) (molar ratio of PPG/PEV: 5/5, kinetic viscosity
at 100.degree. C.: 11.2 mm.sup.2/s)
[0165] POE: Pentaerythritol octanoate (C8 acid) nonanoate (C9 acid)
ester (molar ratio of C8 acid/C9 acid: 1/1.1, kinetic viscosity at
100.degree. C.: 8.6 mm.sup.2/s)
Additives
[0166] Polyphosphate ester compound 1: Mixture of compounds
represented by the general formula (5), in which n is from 1 to
3
[0167] Polyphosphate ester compound 2: Mixture of compounds
represented by the general formula (5), in which n is from 1 to
8
[0168] Polyphosphate ester compound 3: Compound represented by the
general formula (6)
[0169] Polyphosphate ester compound 4: Mixture of compounds
represented by the general formula (1), in which R.sup.1, R.sup.3,
R.sup.5, and R.sup.7 are hydrogen atoms, R.sup.2, R.sup.4, R.sup.6,
and R.sup.8 each are an alkyl group having 1 to 20 carbon atoms,
R.sup.9 is a divalent hydrocarbon group having 2 to 20 carbon
atoms, and n is from 1 to 8
[0170] Diluted product of organic carboxylic acid metal salt:
Dipropylene glycol diluted product of potassium oleate (dilution
degree: 30 times, potassium concentration in diluted product: 4,000
ppm)
[0171] Antioxidant: 2,6-di-tert-butyl-4-methylphenol (DBPC)
[0172] Acid scavenger: 2-Ethylhexyl glycidyl ether
[0173] Anti-foaming agent: Silicone anti-foaming agent
[0174] As is apparent from the results of the lubricating property
test of Examples 1 to 14, the coefficient of friction in the
sliding portion of the refrigerator can be decreased by adding both
the polyphosphate ester compound and the organic carboxylic acid
metal salt to the refrigerator oil. The wear resistance can also be
improved as is apparent from the small ring wear amounts.
[0175] As shown by Comparative Examples 1 to 14, on the other hand,
in the case where any one or both of the polyphosphate ester
compound and the organic carboxylic acid metal salt is not
contained in the refrigerator oil, both the wear resistance and the
coefficient of friction cannot be improved.
* * * * *