U.S. patent application number 13/807377 was filed with the patent office on 2013-04-25 for lubricant base oil and lubricant composition.
This patent application is currently assigned to Idemitsu Kosan Co., Ltd.. The applicant listed for this patent is Yukitoshi Fujinami, Yukio Yoshida. Invention is credited to Yukitoshi Fujinami, Yukio Yoshida.
Application Number | 20130102506 13/807377 |
Document ID | / |
Family ID | 45530142 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130102506 |
Kind Code |
A1 |
Yoshida; Yukio ; et
al. |
April 25, 2013 |
LUBRICANT BASE OIL AND LUBRICANT COMPOSITION
Abstract
A lubricating base oil includes at least one of ionic liquids
containing a compound represented by a formula (1): Z.sup.+A.sup.-,
in which Z.sup.+ represents a cation and A.sup.- represents an
anion, in which Z.sup.+ is a cyclic quaternary ammonium ion having
two different side chains and A.sup.- is a conjugated amide
ion.
Inventors: |
Yoshida; Yukio;
(Sodegaura-shi, JP) ; Fujinami; Yukitoshi;
(Ichihara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yoshida; Yukio
Fujinami; Yukitoshi |
Sodegaura-shi
Ichihara-shi |
|
JP
JP |
|
|
Assignee: |
Idemitsu Kosan Co., Ltd.
Tokyo
JP
|
Family ID: |
45530142 |
Appl. No.: |
13/807377 |
Filed: |
July 27, 2011 |
PCT Filed: |
July 27, 2011 |
PCT NO: |
PCT/JP11/67115 |
371 Date: |
December 28, 2012 |
Current U.S.
Class: |
508/249 ;
508/244; 508/262; 508/268; 508/283; 544/177; 546/184; 546/347;
548/335.1; 548/579 |
Current CPC
Class: |
C10N 2030/10 20130101;
C10N 2030/12 20130101; C10N 2020/02 20130101; C10M 2215/223
20130101; C10M 2223/041 20130101; C10M 2219/0406 20130101; C10N
2020/04 20130101; C10M 105/70 20130101; C10M 2215/2203 20130101;
C10N 2040/30 20130101; C10M 105/72 20130101; C10M 171/00 20130101;
C10M 105/74 20130101; C10M 2215/0425 20130101; C10N 2020/077
20200501; C10N 2040/02 20130101; C10M 2223/0603 20130101; C10M
2215/041 20130101 |
Class at
Publication: |
508/249 ;
508/262; 508/244; 508/283; 508/268; 548/579; 548/335.1; 544/177;
546/347; 546/184 |
International
Class: |
C10M 105/70 20060101
C10M105/70 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2010 |
JP |
2010-171895 |
Claims
1. A lubricating base oil comprising an ionic liquid comprising a
compound of formula (1): Z.sup.+A.sup.- (1) wherein Z.sup.+ is a
cyclic quaternary ammonium cation having two different side chains
and A.sup.- is a conjugated amide anion.
2. The lubricating base oil of claim 1, wherein A.sup.- is of
formula (2): ##STR00018## n is an integer of from 1 to 4, m is an
integer of from 1 to 4, and n and m are allowed to be the same or
different.
3. The lubricating base oil of claim 1, wherein Z.sup.+ is of
formula (3): ##STR00019## n is 1 or 2; X is methylene or oxygen;
and each R.sub.1 and R.sub.2 is independently an alkyl group having
from 1 to 12 carbon atoms, optionally comprising an ether group, an
ester group, a nitrile group and a silyl group.
4. The lubricating base oil of claim 1, wherein the ionic liquid
has a molecular weight of from 410 to 570.
5. The lubricating base oil of claim 1, wherein the ionic liquid
has a kinematic viscosity at of from 1 mm.sup.2/s to 100 mm.sup.2/s
at 40 degrees C.
6. The lubricating base oil of claim 1, wherein the ionic liquid
has a pour point of at most zero degrees C.
7. A lubricating oil composition comprising: the lubricating base
oil of claim 1; and at least one selected from the group consisting
of an antioxidant, an oiliness agent, an extreme pressure agent, a
detergent dispersant, a viscosity index improver, a rust inhibitor,
a metal deactivator and an antifoaming agent.
8. A method of lubricating an object, the method comprising:
contacting the lubricating oil composition of claim 7 with an
object in need thereof, wherein the object is at least one selected
from the group consisting of an oil-impregnated bearing, a fluid
dynamic bearing, vacuum equipment, and semiconductor manufacturing
equipment.
9. The lubricating base oil of claim 2, wherein n is an integer of
from 1 to 2, m is an integer of from 1 to 2, and n and m are
allowed to be the same or different.
10. The lubricating base oil of claim 3, wherein the alkyl group
further comprises at least one selected from the group consisting
of an ether group, an ester group, a nitrile group, and a silyl
group.
11. The lubricating base oil of claim 3, wherein the alkyl group
has from 1 to 6 carbon atoms.
12. The lubricating base oil of claim 3, wherein the alkyl group
has from 1 to 4 carbon atoms.
13. The lubricating base oil of claim 4, wherein the ionic liquid
has a molecular weight of from 410 to 470.
14. The lubricating base oil of claim 4, wherein the ionic liquid
has a molecular weight of from 420 to 440.
15. The lubricating base oil of claim 5, wherein the ionic liquid
has a kinematic viscosity of from 10 mm.sup.2/s to 70 mm.sup.2/s at
40 degrees C.
16. The lubricating base oil of claim 5, wherein the ionic liquid
has a kinematic viscosity of from 20 mm.sup.2/s to 40 mm.sup.2/s at
40 degrees C.
17. The lubricating base oil of claim 6, wherein the ionic liquid
has a pour point of at most -10 degrees C.
18. The lubricating base oil of claim 6, wherein the ionic liquid
has a pour point of at most -20 degrees C.
19. The lubricating base oil of claim 1, wherein the ionic liquid
has an acid value of at most 1 mgKOH/g.
20. The lubricating base oil of claim 1, wherein the ionic liquid
has a flash point of at least 200 degrees C.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lubricating base oil
containing an ionic liquid, and a lubricating oil composition.
BACKGROUND ART
[0002] A lubricating oil generally includes an organic substance
mainly containing hydrocarbons, where lowering the viscosity
necessarily increases vapor pressure and entails evaporation loss
of the lubricating oil and increase in risk of ignition.
Especially, the lubricating oil (e.g. hydraulic oil) used in a
facility such as machinery in an ironworks that handles
high-temperature objects requires fire resistance in order to avoid
fire accidents. Further, precision motors used for recent
information equipment (e.g. hard disk) requires a lubricating oil
exhibiting less evaporation and less scattering in order to
minimize adverse effects on neighboring precision devices.
[0003] On the other hand, in recent years, it has been reported
that an ionic liquid containing cations and anions exhibits an
excellent thermal stability and a high ion conductivity and is
stable even in the air (see, for instance, non-Patent Literature 1)
Utilizing features of thermal stability (i.e., volatility
resistance and fire resistance), high ion density (high ion
conductivity), a large heat capacity, a low viscosity and the like
of the ionic liquid, application of the ionic liquid has been
vigorously studied on various usage such as an electrolyte for a
solar cell (see, for instance, Patent Literature 1), an extraction
separation solvent and a reaction solvent.
[0004] Moreover, use of such an ionic liquid as a lubricating base
oil has been proposed (see, for instance, Patent Literature 2).
Molecules of the ionic liquid are not linked by intermolecular
attraction as in a molecular liquid but are linked by strong ionic
bond. Accordingly, the ionic liquid is hardly volatile, exhibits
fire resistance and stays stable against heat and oxidation. Thus,
the ionic liquid is less evaporative even with a low viscosity and
shows an excellent heat resistance.
CITATION LIST
Patent Literature(s)
[0005] Patent Literature 1: JP-A-2003-31270 [0006] Patent
Literature 2: International Publication WO2005/035702
Non-Patent Literature(s)
[0006] [0007] Non-Patent Literature 1: "J. Chem. Soc., Chem.
Commun." issued in 1992, p. 965
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0008] Although an ionic liquid exhibits a low viscosity, a low
vapor pressure and an excellent heat resistance as a lubricating
base oil, an ionic liquid described in Example of Patent Literature
2 is insufficient since the ionic liquid is highly corrosive to
metals under high-temperature environments. Thus, Patent Literature
2 does not clearly describe what cations and anions are most
suitably selected as an ionic liquid used in a lubricating base
oil.
[0009] Accordingly, in view of the above, an object of the
invention is to provide a lubricating base oil exhibiting a low
vapor pressure even with a low viscosity, no risk of ignition, an
excellent heat resistance, less metal corrosion behavior at high
temperatures and an excellent low-temperature fluidity, and a
lubricating oil composition using the lubricating base oil.
Means for Solving the Problems
[0010] In order to solve the above-described problems, the
invention provides a lubricating base oil and a lubricating oil
composition as follows.
[0011] According to an aspect of the invention, a lubricating base
oil includes at least one of ionic liquids containing a compound
represented by a formula (1): Z.sup.+A.sup.-, in which Z.sup.+
represents a cation and A.sup.- represents an anion, in which
Z.sup.+ is a cyclic quaternary ammonium ion having two different
side chains and A.sup.- is a conjugated amide ion.
[0012] In the lubricating base oil according to the above aspect of
the invention, it is preferable that A.sup.- in the ionic liquid of
the formula (1) is selected from anions having a structure
represented by a formula (2) below.
##STR00001##
[0013] In the formula (2), n is an integer of 1 to 4, m is an
integer of 1 to 4, and n and m are allowed to be the same or
different.
[0014] In the lubricating base oil according to the above aspect of
the invention, it is preferable that Z.sup.+ in the ionic liquid of
the formula (1) is selected from cations having a structure
represented by a formula (3) below.
##STR00002##
[0015] In the formula (3), n is 1 or 2; X is methylene or oxygen;
and R.sub.1 and R.sub.2 each are a group selected from an alkyl
group having 1 to 12 carbon atoms that is allowed to have an ether
group, an ester group, a nitrite group and a silyl group.
[0016] In the lubricating base oil according to the above aspect of
the invention, it is preferable that the ionic liquid has a
molecular weight in a range of 410 to 570.
[0017] In the lubricating base oil according to the above aspect of
the invention, it is preferable that the ionic liquid has a a
kinematic viscosity at 40 degrees C. in a range of 1 mm.sup.2/s to
100 mm.sup.2/s.
[0018] In the lubricating base oil according to the above aspect of
the invention, it is preferable that the ionic liquid has a pour
point of at most zero degrees C.
[0019] According to another aspect of the invention, a lubricating
oil composition containing: the lubricating base oil according to
the above aspect of the invention; and at least one of an
antioxidant, an oiliness agent, an extreme pressure agent, a
detergent dispersant, a viscosity index improver, a rust inhibitor,
a metal deactivator and an antifoaming agent.
[0020] It is preferable that the lubricant oil composition
according to the another aspect of the invention is used for
lubrication of an oil-impregnated bearing, a fluid dynamic bearing,
vacuum equipment and semiconductor manufacturing equipment.
[0021] Accordingly, the invention can provide a lubricating base
oil exhibiting a low vapor pressure even with a low viscosity, no
risk of ignition, an excellent heat resistance, less metal
corrosion behavior at high temperatures and an excellent
low-temperature fluidity, and a lubricating oil composition using
the lubricating base oil.
DESCRIPTION OF EMBODIMENT(S)
[0022] A lubricating base oil according to an exemplary embodiment
includes at least one of later-described ionic liquids.
[0023] Each of the ionic liquids used in the exemplary embodiment
is provided by an ionic liquid containing a compound represented by
a formula (1): Z.sup.+A.sup.-, in which Z.sup.+ represents a cation
and A.sup.- represents an anion.
[0024] The ionic liquid requires Z.sup.+ to be a cyclic quaternary
ammonium ion having two different side chains and A.sup.- to be a
conjugated amide ion in the formula (1).
[0025] It is preferable that A.sup.- in the formula (1) is selected
from anions having a structure represented by a formula (2)
below.
##STR00003##
[0026] In the formula (2), n is an integer of 1 to 4, preferably 1
or 2 in terms of a molecular weight of the ionic liquid. m is an
integer of 1 to 4, preferably 1 or 2 in terms of the molecular
weight of the ionic liquid. m and n may be mutually the same or
different.
[0027] Examples of the anions represented by the formula (2)
include bis(trifluoromethanesulfonyl)amide,
bis(pentafluoroethanesulfonyl)amide,
bis(heptafluoropropanesulfonyl)amide,
bis(nonafluorobutanesulfonyl)amide,
trifluoromethanesulfonyl(pentafluoroethanesulfonyl)amide,
pentafluoroethanesulfonyl(heptafluoropropanesulfonyl)amide,
heptafluoropropanesulfonyl(nonafluorobutanesulfonyl)amide,
trifluoromethanesulfonyl(heptafluoropropanesulfonyl)amide,
pentafluoroethanesulfonyl(nonafluorobutanesulfonyl)amide,
trifluoromethanesulfonyl(nonafluorobutanesulfonyl)amide. Among
these, in terms of the molecular weight of the ionic liquid,
bis(trifluoromethanesulfonyl)amide,
bis(pentafluoroethanesulfonyl)amide, and
trifluoromethanesulfonyl(pentafluoroethanesulfonyl)amide are
preferable, among which bis(trifluoromethanesulfonyl)amide is
particularly preferable.
[0028] It is preferable that Z.sup.+ in the formula (1) is selected
from cations having a structure represented by a formula (3)
below.
##STR00004##
[0029] In the formula (3), n is 1 or 2 and X is methylene or
oxygen. R.sub.1 and R.sub.2 each are a group selected from an alkyl
group having 1 to 12 carbon atoms that may have an ether group
(ether bond), an ester group (ester bond), a nitrile group and a
silyl group. The number of carbon atoms in such an alkyl group is
more preferably 1 to 6, particularly preferably 1 to 4 in terms of
reduction in the viscosity and improvement in heat resistance
(high-temperature oxidation stability) of the ionic liquid.
[0030] Examples of the cations represented by the formula (3)
include 1-butyl-1-methylpyrrolidinium,
1-pentyl-1-methylpyrrolidinium, 1-hexyl-1-methylpyrrolidinium,
1-heptyl-1-methylpyrrolidinium, 1-octyl-1-methylpyrrolidinium,
1-nonyl-1-methylpyrrolidinium, 1-decyl-1-methylpyrrolidinium,
1-undecyl-1-methylpyrrolidinium, 1-dodecyl-1-methylpyrrolidinium,
1-(2-methoxyethyl)-1-methylpyrrolidinium,
1-(2-methoxy-2-oxoethyl)-1-methylpyrrolidinium,
1-cyanomethyl-1-methylpyrrolidinium,
1-trimethylsilylmethyl-1-methylpyrrolidinium,
1-butyl-1-methylpiperidinium, 1-pentyl-1-methylpiperidinium,
1-hexyl-1-methylpiperidinium, 1-heptyl-1-methylpiperidinium,
1-octyl-1-methylpiperidinium, 1-nonyl-1-methylpiperidinium,
1-decyl-1-methylpiperidinium, 1-undecyl-1-methylpiperidinium,
1-dodecyl-1-methylpiperidinium,
1-(2-methoxyethyl)-1-methylpiperidinium,
1-(2-methoxy-2-oxoethyl)-1-methylpiperidinium,
1-cyanomethyl-1-methylpiperidinium,
1-trimethylsilylmethyl-1-methylpiperidinium,
1-butyl-1-methylmorpholinium, 1-pentyl-1-methylmorpholinium,
1-hexyl-1-methylmorpholinium, 1-heptyl-1-methylmorpholinium,
1-octyl-1-methylmorpholinium, 1-nonyl-1-methylmorpholinium,
1-decyl-1-methylmorpholinium, 1-undecyl-1-methylmorpholinium,
1-dodecyl-1-methylmorpholinium,
1-(2-methoxyethyl)-1-methylmorpholinium,
1-(2-methoxy-2-oxoethyl)-1-methylmorpholinium,
1-cyanomethyl-1-methylmorpholinium and
1-trimethylsilylmethyl-1-methylmorpholinium. Among the above, in
terms of reducing the viscosity and improvement in the heat
resistance (high-temperature oxidation stability) of the ionic
liquid, 1-butyl-1-methylpyrrolidinium,
1-pentyl-1-methylpyrrolidinium, 1-hexyl-1-methylpyrrolidinium,
1-(2-methoxyethyl)-1-methylpyrrolidinium,
1-butyl-1-methylpiperidinium,
1-(2-methoxyethyl)-1-methylpiperidinium and
1-(2-methoxyethyl)-1-methylmorpholinium are preferable, among which
1-butyl-1-methylpyrrolidinium,
1-(2-methoxyethyl)-1-methylpyrrolidinium and
1-(2-methoxyethyl)-1-methylpiperidinium are particularly
preferable.
[0031] A molecular weight of the ionic liquid is preferably from
410 to 570, more preferably from 410 to 470, particularly
preferably from 420 to 440. When the molecular weight falls within
the above range, a charge density and an alkyl chain of the cations
range appropriately, thereby reducing the viscosity and improving
the heat resistance (high-temperature oxidation stability) of the
ionic liquid.
[0032] In order to restrain power loss caused by evaporation loss
and viscosity resistance, the kinematic viscosity of the ionic
liquid at 40 degrees C. is preferably in a range of 1 mm.sup.2/s to
100 mm.sup.2/s, more preferably of 10 mm.sup.2/s to 70 mm.sup.2/s,
particularly preferably of 20 mm.sup.2/s to 40 mm.sup.2/s.
[0033] In order to restrain the increase in the viscosity
resistance at low temperatures, the pour point of the ionic liquid
is preferably at most zero degrees C., more preferably at most -10
degrees C., particularly preferably at most -20 degrees C.
[0034] In order to avoid corrosion on to-be-lubricated component,
the acid value of the ionic liquid is preferably at most 1 mgKOH/g,
more preferably at most 0.5 mgKOH/g, particularly preferably at
most 0.3 mgKOH/g.
[0035] In order to reduce evaporation of the base oil, the flash
point of the ionic liquid is preferably at least 200 degrees C.,
more preferably at least 250 degrees C., particularly preferably at
least 300 degrees C.
[0036] In order to avoid excessive change in viscosity according to
the temperature, the viscosity index of the ionic liquid is
preferably at least 80, more preferably at least 100, particularly
preferably at least 120.
[0037] An ion concentration (measured at 20 degrees C.) of the
ionic liquid is preferably at least 1 mol/dm.sup.3, more preferably
at least 1.5 mol/dm.sup.3, particularly preferably at least 2
mol/dm.sup.3. The ion concentration of the ionic liquid is
calculated by [density (g/cm.sup.3)/molecular weight Mw
(g/mol)].times.1000. When the ion concentration of the ionic liquid
is less than 1 mol/dm.sup.3, low evaporativity and heat-resistance
(i.e., features of the ionic liquid) are disadvantageously
lowered.
[0038] Although the lubricating base oil in the exemplary
embodiment contains at least one of the aforementioned ionic
liquid, the lubricating base oil in the exemplary embodiment may
contain other compositions (e.g., ethyl acetate) in addition to the
ionic liquid. However, in order to be advantageous as the
lubricating base oil in the exemplary embodiment, a ratio of the
ionic liquid in the lubricating base oil is preferably at least 50
mass %, more preferably at least 70 mass %, further preferably at
least 90 mass %, particularly preferably 100 mass %.
[0039] The lubricating base oil in the exemplary embodiment is
usable for a variety of applications by containing a predetermined
additive. Examples of the additive include an antioxidant, an
oiliness agent, an extreme pressure agent, a detergent dispersant,
a viscosity index improver, a rust inhibitor, a metal deactivator
and an antifoaming agent. One of the additives may be solely used
or at least two of the additives may be used in combination. It
should be noted that the lubricating base oil may be directly used
without containing the additives depending on usage.
[0040] Examples of the antioxidant include an aminic antioxidant, a
phenolic antioxidant, a phosphorous antioxidant and a sulfuric
antioxidant. One of the antioxidants may be solely used or at least
two of the antioxidants may be used in combination. Examples of the
aminic antioxidant include: monoalkyldiphenylamine compounds such
as monooctyldiphenylamine and monononyldiphenylamine;
dialkyldiphenylamine compounds such as 4,4'-dibutyldiphenylamine,
4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine,
4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine and
4,4'-dinonyldiphenylamine; polyalkyldiphenylamine compounds such as
tetrabutyldiphenylamine, tetrahexyldiphenylamine,
tetraoctyldiphenylamine and tetranonyldiphenylamine; and
naphthylamine compounds such as alpha-naphthylamine,
phenyl-alpha-naphthylamine, butylphenyl-alpha-naphthylamine,
pentylphenyl-alpha-naphthylamine, hexylphenyl-alpha-naphthylamine,
heptylphenyl-alpha-naphthylamine, octylphenyl-alpha-naphthylamine
and nonylphenyl-alpha-naphthylamine.
[0041] Examples of the phenolic antioxidant include: monophenolic
compounds such as 2,6-di-tert-butyl-4-methylphenol and
2,6-di-tert-butyl-4-ethylphenol; and diphenolic compounds such as
4,4'-methylenebis(2,6-di-tert-butylphenol) and
2,2'-methylenebis(4-ethyl-6-tert-butylphenol).
[0042] Examples of the sulfuric antioxidant include: thioterpene
compounds such as
2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)-
phenol and a reactant of phosphorus pentasulfide and pinene; and
dialkyl thiodipropionate such as dilauryl thiodipropionate and
distearyl thiodipropionate.
[0043] Examples of the phosphorous antioxidant include triphenyl
phosphite and diethyl
[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate.
[0044] A content of the antioxidant is typically in a range of 0.01
mass % to 10 mass % based on a total amount of the lubricating oil,
preferably in a range of 0.03 mass % to 5 mass %.
[0045] Examples of the oiliness agent include: aliphatic alcohol;
fatty acid compounds such as fatty acid and fatty acid metal salt;
ester compounds such as polyol ester, sorbitan ester and glyceride;
and amine compounds such as aliphatic amine. In view of blending
effects, a content of the oiliness agent is typically in a range of
0.1 mass % to 30 mass % based on the total amount of the
lubricating oil, preferably in a range of 0.5 mass % to 10 mass
%.
[0046] Examples of the extreme pressure agent include a sulfuric
extreme pressure agent, a phosphorus extreme pressure agent, an
extreme pressure agent containing sulfur and metal and an extreme
pressure agent containing phosphorous and metal. One of the extreme
pressure agents may be solely used or at least two of the extreme
pressure agents may be used in combination. Any extreme pressure
agent may be used as long as the extreme pressure agent contains at
least one of a sulfur atom and a phosphorous atom in a molecule and
exhibits load bearing and wear resistance. Examples of the extreme
pressure agent containing sulfur in the molecule include sulfurized
fat and oil, sulfurized fatty acid, ester sulfide, olefin sulfide,
dihydrocarbyl polysulfide, a thiadiazole compound, an
alkylthiocarbamoyl compound, a triazine compound, a thioterpene
compound and a dialkyl thiodipropionate compound.
[0047] Examples of the extreme pressure agent containing sulfur,
phosphorous and metal include: zinc dialkylthiocarbamate (Zn-DTC),
molybdenum dialkylthiocarbamate (Mo-DTC), lead
dialkylthiocarbamate, tin dialkylthiocarbamate, zinc
dialkyldithiocarbamate (Zn-DTP), molybdenum dialkyldithiophosphate
(Mo-DTP), sodium sulfonate and calcium sulfonate. Representative
examples of the extreme pressure agent containing phosphorous in
the molecule include phosphate such as tricresyl phosphate, and an
amine salt thereof. In view of the blending effects and economical
efficiency, a content of the extreme pressure agent is typically in
a range of 0.01 mass % to 30 mass % based on the total amount of
the lubricating oil, preferably in a range of 0.01 mass % to 10
mass %.
[0048] Examples of the detergent dispersant include metal
sulfonates, metal salicylates, metal phenates and succinimides. In
view of the blending effects, a content of the detergent dispersant
is typically in a range of 0.1 mass % to 30 mass % based on the
total amount of the lubricating oil, preferably in a range of 0.5
mass % to 10 mass %.
[0049] Examples of the viscosity index improver include
polymethacrylate, dispersive polymethacrylate, an olefin copolymer
(e.g. an ethylene-propylene copolymer), a dispersive olefin
copolymer and a styrene copolymer (e.g. a styrene-diene copolymer
hydride). In view of the blending effects, a content of the
viscosity index improver is typically in a range of 0.5 mass % to
35 mass % based on the total amount of the lubricating oil,
preferably in a range of 1 mass % to 15 mass %.
[0050] Examples of the rust inhibitor include metal sulfonates,
succinates and alkanolamines such as alkylamines and
monoisopropanolamines. In view of the blending effects, a content
of the rust inhibitor is typically in a range of 0.01 mass % to 10
mass % based on the total amount of the lubricating oil, preferably
in a range of 0.05 mass % to 5 mass %.
[0051] Examples of the metal deactivator include benzotriazole and
thiadiazole. In view of the blending effects, a content of the
metal deactivator is typically in a range of 0.01 mass % to 10 mass
% based on the total amount of the lubricating oil, preferably in a
range of 0.01 mass % to 1 mass %.
[0052] Examples of the antifoaming agent include methyl silicone
oil, fluorosilicone oil and polyacrylates. In view of the blending
effects, a content of the antifoaming agent is typically about
0.0005 mass % to 0.01 mass % based on the total amount of the
lubricating oil.
[0053] In order to avoid lowering of viscosity and corrosion, a
water content in a lubricating oil composition in the exemplary
embodiment is preferably at most 3000 mass ppm based on the
composition, more preferably at most 500 mass ppm, particularly
preferably at most 100 mass ppm.
[0054] The lubricating base oil in the exemplary embodiment
exhibits an extremely low metal corrosion behavior, a low vapor
pressure even with a low viscosity and no risk of ignition.
Accordingly, the lubricating base oil can be applied to various
fields in a direct manner or as the lubricating oil composition
added with the above additives.
[0055] For instance, the lubricating base oil can be preferably
used for: an internal combustion engine; a torque transmitter such
as fluid coupling, automatic transmission (AT) and
continuously-variable transmission (CVT); a bearing (e.g. slide
bearing, ball bearing, oil-impregnated or oil-retaining bearing,
fluid dynamic bearing); a compressor; a chain; a gear; a hydraulic
device; a vacuum pump; a timepiece component; a hard disc; an
aerospace instrument such as airplane and artificial satellite; a
sealing instrument; a motor; and the like. The lubricating base oil
can also be applied to a rolling device such as a ball screw and a
rolling guide surface, a clutch control rotation transmitter, a
power-steering device, a reciprocating compressor and a
turbocharger.
[0056] Further, the lubricating base oil in the exemplary
embodiment can also be suitable as a metalworking fluid (cutting,
pressing and forging), a mold releasing agent, a heat-treating
agent, a heat medium, a cooling agent, a rust inhibitor, a
buffering agent such as a damper and a conductive lubricating agent
that requires conductivity.
[0057] The lubricating base oil in the exemplary embodiment is also
applicable as a base oil of grease. Examples of a thickener of
grease include: a metal soap thickener such as a lithium salt and a
calcium salt; and a non-metal thickener. Examples of the non-metal
thickener includes, for instance, bentonite, silica and fluorine
resin powder. The lubricating base oil in the exemplary embodiment
is also applicable as a base oil of gelatinous material other than
grease.
[0058] Further, the invention is suitable as a machinery material
containing iron, copper, aluminum and zinc. The invention is
especially suitable when known corrosion-resistant materials such
as stainless steel (martensite, ferrite, austenite), ceramic
material (e.g. silicon nitride (Si.sub.3N.sub.4), silicon carbide
(SiC), alumina (Al.sub.2O.sub.3), aluminum nitride (AlN), boron
carbide (B.sub.4C), titanium boride (TiB.sub.2), boron nitride
(BN), titanium carbide (TiC), titanium nitride (TiN), zirconia
(ZrO.sub.2) and the like are used and when a material on which
various coating processing is conducted by DLC
(diamond-like-carbon) processing is used.
[0059] Further, the invention is also suitably used in a device for
conducting physical vapor deposition (PVD) or chemical vapor
deposition (CVD). Examples of the physical vapor deposition include
vacuum deposition, sputtering, ion plating and ion implantation
using various ion guns. Examples of the vacuum deposition include
electron beam evaporation, ion-assisted electron beam evaporation,
arc evaporation and the like as well as general resistance heating
evaporation. The physical evaporation may be conducted in
combination. Examples of the CVD include thermal CVD, plasma CVD,
optical CVD, epitaxial CVD, and atomic-layer CVD. The chemical
vapor deposition may be used in combination or, alternatively, may
be used in combination with physical vapor deposition.
[0060] The PVD device and CVD device using the lubricating base oil
(or the lubricating oil composition) in the exemplary embodiment
is, for instance, suitably used for manufacturing a display
element.
EXAMPLES
[0061] Next, the invention will be further described in detail
based on Examples and Comparatives, which by no means limit the
invention. It should be noted that the properties (i.e., kinematic
viscosity, viscosity index, pour point, 5%-mass reducing
temperature, friction property and metal corrosion behavior) of the
lubricating base oil and the lubricating oil composition were
evaluated or measured according to the following methods.
[0062] (1) Kinematic Viscosity
[0063] A kinematic viscosity was measured according to "Crude
petroleum and petroleum products-Determination of kinematic
viscosity and calculation of viscosity index from kinematic
viscosity" defined in JIS (Japanese Industrial Standards)
K2283.
[0064] (2) Viscosity Index
[0065] A viscosity index was measured according to "Crude petroleum
and petroleum products-Determination of kinematic viscosity and
calculation of viscosity index from kinematic viscosity" defined in
JIS K2283.
[0066] (3) Pour Point
[0067] A pour point was measured according to the method described
in JIS K2269.
[0068] (4) 5%-Mass Reducing Temperature
[0069] Using a differential thermal analyzer, the temperature was
raised at a rate of 10 degrees C./min and the temperature at which
initial mass was reduced by 5% was measured. Higher 5%-mass
reducing temperature indicates more excellent evaporation
resistance and heat-resistance.
[0070] (5) Friction Property (Friction Coefficient and Wear
Width)
[0071] Using a ball-on-disc type reciprocating friction tester
(Bowden-Leben type), a friction coefficient and a wear width were
measured under conditions of 20N-load, 80-degree-C. temperature,
30-mm.sup.2/s sliding velocity and 15-mm stroke. The ball is made
of a material denoted by SUJ2 and has a 10-mm diameter. The disc is
made of a material denoted by SUJ2. Lower friction coefficient and
wear width indicate more excellent lubricity and wear
resistance.
[0072] (6) Metal Corrosion Behavior
[0073] One of iron sintered bearings (having an iron content of at
least 99 mass %) and one of copper sintered bearings (having a
copper content of 93 mass % to 98 mass %, a tin content of 2 mass %
to 7 mass %, and a content of other metals of at most 1 mass %)
were simultaneously soaked in an 8-mL ionic liquid and left still
for 240 hours at 140 degrees C. Then, an appearance of the ionic
liquid was observed. Each of the bearings has 12-mm outer diameter
and a 4-mm thickness. Metal corrosion behavior was evaluated
according to the following criteria: [0074] A: Neither metal
elution nor corrosion was observed. [0075] B: A brownish or black
eluted substance was slightly observed (the substance was slightly
corroded). [0076] C: A brownish or black eluted substance was
observed (the substance was corroded).
[0077] Ionic Liquids
[0078] The following ionic liquids were synthesized or prepared as
follows.
(1) Ionic Liquid 1: 1-butyl-1-methylpyrrolidinium
bis(trifluoromethanesulfonyl)amide
[0079] 1-methylpyrrolidine (50 g, 0.585 mol) and 2-propanol (70 mL)
were added to a 1-L flask under a nitrogen atmosphere. After
1-bromobutane (96.5 g, 0.705 mol) was dropped therein, the mixture
was raised to 40 degrees C. and was reacted for six hours. After
completion of the reaction, the mixture was recrystallized with
ethyl acetate and subjected to filtration. The obtained crystals
were washed for several times with ethyl acetate. Subsequently, the
crystals were dried at 40 degrees C. for several hours under
reduced pressure using a vacuum pump to obtain
1-butyl-1-methylpyrrolidinium bromide (halogen body) (113 g, 0.510
mol).
[0080] Next, the halogen body (113 g, 0.510 mol) and deionized
water (110 mL) were put into the 1-L flask, into which an aqueous
solution prepared by dissolving lithium
bis(trifluoromethanesulfonyl)imide (151 g, 0.525 mol) in deionized
water (150 mL) was dropped. After being stirred for about one hour
at the room temperature, the reaction mixture was transferred to a
1-L separating funnel and was extracted with methylene chloride
(230 mL). The collected methylene chloride solution was washed for
several times with deionized water. After washing, an aqueous layer
(in a range of 1 mL to 2 mL) was collected and reacted with a 0.5M
silver nitrate solution (1 mL), where the presence of precipitates
was checked. (If white precipitates were observed, since bromide
ions were not completely removed, washing is repeated until the
precipitates are not confirmed.) After completion of water-washing,
the reaction mixture was condensed using a rotary evaporator, to
which a little amount of activated carbon was added and stirred for
one day at the room temperature. The mixture was put into a column
of a neutral alumina and was heated at 60 degrees C. for four hours
with stirring under reduced pressure using a vacuum pump to obtain
a target compound (212 g, 0.50 mol). A chemical formula of the
compound is shown below.
##STR00005##
(2) Ionic Liquid 2: 1-hexyl-1-methylpyrrolidinium
bis(trifluoromethanesulfonyl)amide
[0081] Except that 1-bromohexane (116 g, 0.705 mol) was used
instead of 1-bromobutane, the same process as in synthesizing the
ionic liquid 1 was conducted to obtain
1-hexyl-1-methylpyrrolidinium bromide (117 g, 0.468 mol). Except
that this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (202 g, 0.449 mol). A chemical formula of the compound is
shown below.
##STR00006##
(3) Ionic Liquid 3: 1-(2-methoxyethyl)-1-methylpyrrolidinium
bis(trifluoromethanesulfonyl)amide
[0082] Except that 2-iodoethylmethylether (131 g, 0.705 mol) was
used instead of 1-bromobutane, the same process as in synthesizing
the ionic liquid 1 was conducted to obtain
1-(2-methoxyethyl)-1-methylpyrrolidinium iodide (146 g, 0.538 mol).
Except that this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (212 g, 0.500 mol). A chemical formula of the compound is
shown below.
##STR00007##
(4) Ionic Liquid 4: 1-butyl-1-methylpiperidinium
bis(trifluoromethanesulfonyl)amide
[0083] Except that 1-methylpiperidine (58 g, 0.585 mol) was used
instead of 1-methylpyrrolidine and the reaction temperature was 80
degrees C., the same process as in synthesizing the ionic liquid 1
was conducted to obtain 1-butyl-1-methylpiperidinium bromide (137
g, 0.579 mol). Except that this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (250 g, 0.573 mol). A chemical formula of the compound is
shown below.
##STR00008##
(5) Ionic Liquid 5: 1-(2-methoxyethyl)-1-methylpiperidinium
bis(trifluoromethanesulfonyl)amide
[0084] Except that 1-methylpiperidine (58 g, 0.585 mol) was used
instead of 1-methylpyrrolidine and the reaction temperature was 60
degrees C., the same process in synthesizing the ionic liquid 3 was
conducted to obtain 1-(2-methoxyethyl)-1-methylpiperidinium iodide
(161 g, 0.563 mol). Except that this quaternary salt was used
instead of 1-butyl-1-methylpyrrolidinium bromide, the same process
as in synthesizing the ionic liquid 1 was conducted to obtain a
target compound (241 g, 0.549 mol). A chemical formula of the
compound is shown below.
##STR00009##
(6) Ionic Liquid 6: 1-(2-methoxyethyl)-1-methylmorpholinium
bis(trifluoromethanesulfonyl)amide
[0085] Except that 1-methylmorpholine (59 g, 0.585 mol) was used
instead of 1-methylpiperidine and the reaction temperature was 80
degrees C., the same process as in synthesizing the ionic liquid 3
was conducted to obtain 1-(2-methoxyethyl)-1-methylmorpholinium
iodide (145 g, 0.505 mol). Except that this quaternary salt was
used instead of 1-butyl-1-methylpyrrolidinium bromide, the same
process as in synthesizing the ionic liquid 1 was conducted to
obtain a target compound (202 g, 0.460 mol). A chemical formula of
the compound is shown below.
##STR00010##
(7) Ionic Liquid 7: 1-butylpyridinium
bis(trifluoromethanesulfonyl)amide
[0086] Except that pyridine (46 g, 0.585 mol) was used instead of
1-methylpyrrolidine and acetonitrile (200 mL) was used instead of
2-propanol and the reaction temperature was 80 degrees C., the same
process as in synthesizing the ionic liquid 1 was conducted to
obtain 1-butylpyridinium bromide (125 g, 0.579 mol). Except that
this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (234 g, 0.562 mol). A chemical formula of the compound is
shown below.
##STR00011##
(8) Ionic Liquid 8: N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium
bis(trifluoromethanesulfonyl)amide
[0087] The ionic liquid 8 was purchased from KANTO CHEMICAL CO.,
INC. A chemical formula of the compound is shown below.
##STR00012##
(9) Ionic Liquid 9: N,N,N-trimethyl-N-pentyl ammonium
bis(trifluoromethanesulfonyl)amide
[0088] A 3.2M solution of trimethylamine in methanol (183 mL, 0.585
mol) and 1-iodopentane were added to a 1-L flask under a nitrogen
atmosphere and reacted for several hours at the room temperature.
After completion of the reaction, the solvent was removed under
reduced pressure. A residue was washed several times with ethyl
acetate and acetonitrile. Subsequently, the residue was dried for
several hours under reduced pressure using a vacuum pump to obtain
N,N,N-trimethyl-N-pentyl ammonium iodide (89 g, 0.346 mol). Except
that this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (138 g, 0.336 mol). A chemical formula of the compound is
shown below.
##STR00013##
(10) Ionic Liquid 10: triethyl(octyl)phosphonium
bis(trifluoromethanesulfonyl)amide
[0089] A 20% solution of triethylphosphine in toluene (346 g, 0.585
mol) and 1-iodooctane (211 g, 0.878 mol) were added to a 1-L flask
under a nitrogen atmosphere and reacted at 60 degrees C. for
several hours. After completion of the reaction, the mixture was
washed for several times with ethyl acetate and dried at 40 degrees
C. for several hours under reduced pressure using a vacuum pump to
obtain triethyl(octyl)phosphonium iodide (176 g, 0.491 mol). Except
that this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (241 g, 0.471 mol). A chemical formula of the compound is
shown below.
##STR00014##
(11) Ionic Liquid 11: 1-butyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)amide
[0090] 1-methylimidazole (173 g, 2.100 mol) and 1-chlorobutane (234
g, 2.528 mol) were added to a 1-L flask under a nitrogen atmosphere
and reacted at 90 degrees C. for several hours. After completion of
the reaction, the reaction mixture was recrystallized with ethyl
acetate and acetonitrile and subjected to filtration. The obtained
crystals were washed at 40 degrees C. for several times under
reduced pressure using a vacuum pump to obtain
1-butyl-1-methylimidazolium chloride (352 g, 2.016 mol). Except
that this quaternary salt was used instead of
1-butyl-1-methylpyrrolidinium bromide, the same process as in
synthesizing the ionic liquid 1 was conducted to obtain a target
compound (837 g, 1.996 mol). A chemical formula of the compound is
shown below.
##STR00015##
(12) Ionic Liquid 12: 1-butyl-1-methylpyrrolidinium
trifluorotris(pentafluoroethyl)phosphate
[0091] The ionic liquid 12 was purchased from Merck Ltd. A chemical
formula of the compound is shown below.
##STR00016##
(13) Ionic Liquid 13: 1-butyl-1-methylpyrrolidinium
trifluoromethanesulfonate
[0092] 1-butylpyrrolidine (34 g, 0.267 mol) and toluene (230 mL)
were added to a 1-L flask under a nitrogen atmosphere. A mixture
solution of methyltriflate (43 g, 0.262 mol) and toluene (100 mL)
was dropped into the flask at zero degrees C. and reacted at the
same temperature for 24 hours. After completion of the reaction,
the reaction mixture was washed several times with toluene and
treated with activated carbon. The reaction mixture was put into a
column of a neutral alumina and was heated at 60 degrees C. for
four hours with stirring under reduced pressure using a vacuum pump
to obtain a target compound (68 g, 0.233 mol). A chemical formula
of the compound is shown below.
##STR00017##
Examples 1 to 8 and Comparatives 1 to 7
[0093] Using the above ionic liquids and the following additives,
according to formulation shown in Tables 1 and 2, lubricating base
oils or lubricating oil compositions were prepared. The above
properties (i.e., kinematic viscosity, viscosity index, pour point,
5%-mass reducing temperature, friction property and metal corrosion
behavior) of the lubricating base oils and the lubricating oil
compositions were evaluated or measured. The results are shown in
Tables 1 and 2 together with the formulation.
Extreme pressure agent: tricresyl phosphate Metal deactivator:
benzotriazole
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4
Example 5 Example 6 Example 7 Example 8 formulation base oil ionic
liquid 1 100 99.9 98.9 (mass %) ionic liquid 2 100 ionic liquid 3
100 ionic liquid 4 100 ionic liquid 5 100 ionic liquid 6 100
additive extreme pressure agent -- -- -- -- -- -- -- 1 metal
deactivator -- -- -- -- -- -- 0.1 0.1 evaluation items base oil
molecular weight 422 450 424 436 438 440 422 422 kinematic
viscosity at 40.degree. C. 30.06 42.33 21.34 61.20 35.72 80.79
29.85 30.19 (mm.sup.2/s) kinematic viscosity at 100.degree. C.
6.364 7.696 5.170 8.889 6.548 9.535 6.315 6.330 (mm.sup.2/s)
viscosity index 171 153 187 121 139 94 170 168 pour point (.degree.
C.) <-50 -15 <-50 -40 <-50 -40 -40 -40 5%-mass reducing
temp. 380 372 388 383 379 366 377 378 (.degree. C.) corrosion
behavior A A A A A A A A friction coefficient 0.079 0.077 0.082
0.089 0.089 0.084 0.086 0.082 wear width (mm) 0.32 0.28 0.28 0.24
0.32 0.23 0.11 0.10
TABLE-US-00002 TABLE 2 Comparative Comparative Comparative
Comparative Comparative Comparative Comparative 1 2 3 4 5 6 7
formulation base oil ionic liquid 7 100 (mass %) ionic liquid 8 100
ionic liquid 9 100 ionic liquid 10 100 ionic liquid 11 100 ionic
liquid 12 100 ionic liquid 13 100 additive extreme pressure agent
-- -- -- -- -- -- -- metal deactivator -- -- -- -- -- -- --
evaluation items base oil molecular weight 416 426 410 512 419 587
291 kinematic viscosity at 22.86 26.45 45.15 45.79 19.96 61.00
65.08 40.degree. C. (mm.sup.2/s) kinematic viscosity at 5.117 5.450
7.566 7.675 4.732 8.662 10.705 100.degree. C. (mm.sup.2/s)
viscosity index 162 148 134 135 166 115 155 pour point (.degree.
C.) 26 -50 25 <-50 <-50 4 3 5%-mass reducing temp. 365 365
356 356 397 325 367 (.degree. C.) corrosion behavior B B A C C C B
friction coefficient 0.098 0.086 0.072 0.068 0.093 0.072 0.048 wear
width (mm) 0.31 0.30 0.27 0.24 0.34 <0.01 0.21
[0094] As clearly recognized from the evaluation results shown in
Tables 1 and 2, the lubricating base oils or the lubricating oil
compositions obtained in Examples 1 to 8 exhibited favorable heat
resistance and lubricity in addition to less metal corrosion
behavior at higher temperatures and an excellent low-temperature
fluidity. On the other hand, it was recognized that, when using an
ionic liquid not satisfying that the cation was a cyclic quaternary
ammonium ion having two different side chains and the anion was a
conjugated amide ion, less metal corrosion behavior at higher
temperatures and an excellent low-temperature fluidity were not
simultaneously achieved although heat resistance and lubricity were
excellent, so that the obtained compound was not appropriate as the
lubricating base oil.
* * * * *