U.S. patent application number 10/250427 was filed with the patent office on 2004-03-18 for lubricating oil composition.
Invention is credited to Baba, Yoshiharu.
Application Number | 20040053794 10/250427 |
Document ID | / |
Family ID | 26607325 |
Filed Date | 2004-03-18 |
United States Patent
Application |
20040053794 |
Kind Code |
A1 |
Baba, Yoshiharu |
March 18, 2004 |
Lubricating oil composition
Abstract
Lubricating oil composition comprising
.beta.-dithiophosphorylated propionic acid (A), triaryl phosphate
(B) and base oil comprising mineral oil and/or synthetic oil.
Inventors: |
Baba, Yoshiharu; (Kanagawa,
JP) |
Correspondence
Address: |
Richard F Lemuth
Shell Oil Company
Intellectual Property
PO Box 2463
Houston
TX
77252-2463
US
|
Family ID: |
26607325 |
Appl. No.: |
10/250427 |
Filed: |
July 1, 2003 |
PCT Filed: |
January 2, 2002 |
PCT NO: |
PCT/EP02/00041 |
Current U.S.
Class: |
508/430 ;
508/433 |
Current CPC
Class: |
C10M 2203/1085 20130101;
C10M 2215/221 20130101; C10N 2040/046 20200501; C10N 2040/135
20200501; C10M 2215/226 20130101; C10M 101/02 20130101; C10M 137/04
20130101; C10M 2223/042 20130101; C10M 2223/047 20130101; C10M
2219/042 20130101; C10M 2207/023 20130101; C10M 2219/106 20130101;
C10M 2215/064 20130101; C10M 2203/1045 20130101; C10M 137/00
20130101; C10M 2203/1065 20130101; C10M 2207/289 20130101; C10M
2215/066 20130101; C10M 2215/06 20130101; C10M 2219/102 20130101;
C10M 2207/026 20130101; C10M 2215/22 20130101; C10M 2219/10
20130101; C10M 2203/1006 20130101; C10M 2215/225 20130101; C10M
2207/046 20130101; C10M 2215/065 20130101; C10M 137/105 20130101;
C10M 169/04 20130101; C10N 2040/04 20130101; C10N 2040/042
20200501; C10M 2219/104 20130101; C10M 2223/041 20130101; C10N
2040/02 20130101; C10M 2223/04 20130101; C10M 2223/00 20130101;
C10N 2040/044 20200501; C10N 2040/08 20130101; C10M 2215/30
20130101; C10M 2219/108 20130101; C10M 2203/1025 20130101; C10M
2207/024 20130101 |
Class at
Publication: |
508/430 ;
508/433 |
International
Class: |
C10M 137/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 4, 2001 |
JP |
200193 |
Mar 1, 2001 |
JP |
200157423 |
Claims
1. Lubricating oil composition, comprising
.beta.-dithiophosphorylated propionic acid (A), triaryl phosphate
(B) and base oil comprising mineral oil and/or synthetic oil.
2. Lubricating oil composition according to claim 1, wherein the
.beta.-dithiophosphorylated propionic acid (A) is represented by
the general formula (1)
below:S.dbd.P(--OR.sup.1).sub.2SCH.sub.2CH(R.sup.2)CO- OH
(1)wherein R.sup.1, which may be identical or different, represents
a branched alkyl group of from 3 to 8 carbon atoms and R.sup.2
represents a hydrogen atom or alkyl group of from 1 to 4 carbon
atoms.
3. Lubricating oil composition according to claim 2, where R.sup.2
is a methyl group, ethyl group or hydrogen group.
4. Lubricating oil composition according to any one of claims 1 to
3, wherein the .beta.-dithiophosphorylated propionic acid (A) is
selected from 3-(O,O-diisopropyldithiophosphoryl)propionic acid,
3-(O,O-diisopropyldithiophosphoryl)-2-methyl-propionic acid,
3-(O,O-diisobutyldithiophosphoryl)-propionic acid and
3-(O,O-diisobutyldithiophosphoryl)-2-methyl-propionic acid.
5. Lubricating oil composition according to any one of claims 1 to
4, in which from 0.001 to 1.0% by weight of
.beta.-dithiophosphorylated propionic acid (A) is incorporated
therein, with respect to the total amount of lubricating oil
composition.
6. Lubricating oil composition according to any one of claims 1 to
5, in which from 0.001 to 0.5% by weight of
.beta.-dithiophosphorylated propionic acid (A) is incorporated
therein, with respect to the total amount of lubricating oil
composition.
7. Lubricating oil composition according to any one of claims 1 to
6, wherein the triaryl phosphate (B) is represented by the general
formula (2) below:O.dbd.P(--O--R.sup.3).sub.3 (2)wherein each
R.sup.3 is, independently, a phenyl group or a phenyl group having
alkyl group(s) of from 1 to 9 carbon atoms.
8. Lubricating oil composition according to any one of claims 1 to
7, in which from 0.05 to 10% by weight of triaryl phosphate (B) is
incorporated therein, with respect to the total amount of
lubricating oil composition.
9. Lubricating oil composition according to any one of claims 1 to
8, in which from 0.05 to 5% by weight of triaryl phosphate (B) is
incorporated therein, with respect to the total amount of
lubricating oil composition.
10. Use of a lubricating oil composition according to any of claims
1 to 9, in a hydraulic machine, a compressor, a turbine, a bearing
and/or a gear.
Description
[0001] The present invention relates to a lubricating oil
composition which exhibits excellent lubricating performance, even
under severe high pressure/high load working conditions.
[0002] The use of industrial machines at higher speeds, under
higher pressures, and the miniaturization thereof has resulted in
machine elements such as hydraulic machines, compressors, turbines,
gear elements and bearings being operated under severer
conditions.
[0003] The lubricating oil used must therefore exhibit excellent
lubricating performance to sufficiently guarantee the life of these
machines over long periods even when they are used at high
pressure, high speed, high load and high temperatures.
[0004] In response to these demands, zinc dialkyl dithiophosphates
have been used in anti-wear lubricating oil compositions for
lubricating oils for industrial machines. However these compounds
are disadvantageous in terms of their instability to hydrolysis on
contamination with water and their instability to thermal oxidation
at high temperature and high pressure, and in that an unpleasant
odour is generated as the lubricating oil deteriorates.
[0005] In addition to the abovementioned problems, there are
increasing concerns over the use of zinc compounds such as zinc
dialkyl dithiophosphates in view of recent questions regarding
environmental protection and toxicity.
[0006] Anti-wear lubricating oil compositions comprising sulphur
compounds, phosphorous compounds and phosphorous-sulphur-based
combinations thereof are already known as zinc-free anti-wear
lubricating oils which do not contain zinc dialkyl
dithiophosphates.
[0007] Specifically, the combination of sulphurated hydrocarbon and
acidic phosphoric acid ester and the combination of triaryl
phosphorothionate, triaryl phosphate and acidic phosphate ester
amine salt, as disclosed in GB Patent Number 1415964, are known,
but the corrosive properties and odour of sulphurated hydrocarbon
poses problems, and highly active acidic phosphate esters are
disadvantageous in that, for example, they cause hydrolytic
deterioration and a decrease in thermal oxidation stability.
[0008] The present invention therefore aims to provide a
lubricating oil composition which contains as little ash (e.g.
zinc) as possible and has excellent anti-wear properties, even when
used under severe high pressure, high speed and high load
conditions, and which is excellent in terms of its thermal
oxidation stability, water resistance and odour and also in terms
of the environment, safety and its lubricating oil performance in
practice.
[0009] The present invention provides a lubricating oil
composition, comprising .beta.-dithiophosphorylated propionic acid
(A), triaryl phosphate (B) and base oil comprising mineral oil
and/or synthetic oil.
[0010] In a preferred embodiment, .beta.-dithiophosphorylated
propionic acid (A) is represented by the general formula (1)
below:
S.dbd.P(--OR.sup.1).sub.2SCH.sub.2CH(R.sup.2)COOH (1)
[0011] wherein R.sup.1, which may be identical or different,
represents a branched alkyl group of from 3 to 8 carbon atoms,
preferably from 3 to 4 carbon atoms, and R.sup.2 represents a
hydrogen atom or an alkyl group of from 1 to 4 carbon atoms.
R.sup.1 can be chosen from the following branched alkyl
groups:--isopropyl group, branched butyl group, branched pentyl
group, branched hexyl group, branched heptyl group, and branched
octyl group.
[0012] Examples of R.sup.2 include hydrogen, methyl, ethyl, propyl
and butyl groups. Preferably, R.sup.2 is a methyl group, ethyl
group or hydrogen group. It is particularly preferred that R.sup.2
is methyl.
[0013] Specific examples of such compounds include
3-(O,O-diisopropyldithi- ophosphoryl)propionic acid,
3-(O,O-diisopropyldithiophosphoryl)-2-methyl-p- ropionic acid,
3-(O,O-diisobutyldithiophosphoryl)-propionic acid and
3-(O,O-diisobutyldithiophosphoryl)-2-methyl-propionic acid.
[0014] The amount of .beta.-dithiophosphorylated propionic acid (A)
added in the present invention is preferably from 0.001 to 1.0% by
weight, more preferably from 0.001 to 0.5% by weight, even more
preferably from 0.001 to 0.1% by weight, and most preferably from
0.005 to 0.05% by weight, with respect to the total amount of
lubricating oil composition.
[0015] If the amount of (A) added is less than 0.001% by weight,
adequate synergistic effects may not be achieved, whereas if the
amount of (A) added exceeds 0.5% by weight, the lubricating
performance reaches saturation, and there may be a deterioration in
thermal oxidation stability, hydrolysis stability and corrosion
properties, which is undesirable.
[0016] In a preferred embodiment, the triaryl phosphate (B) is
represented by the general formula (2) below:
O.dbd.P(--O--R.sup.3).sub.3 (2)
[0017] wherein each R.sup.3 is independently a phenyl group or a
phenyl group having alkyl group(s) of from 1 to 9 carbon atoms.
[0018] Specific examples of suitable triaryl phosphates (B) include
triphenyl phosphate ester, tricresyl phosphate ester, triethyl
phenyl phosphate ester, tripropyl phenyl phosphate ester, tributyl
phenyl phosphate ester, triheptyl phenyl phosphate ester, trihexyl
phenyl phosphate ester, triheptyl phenyl phosphate ester, trioctyl
phenyl phosphate ester and trinonyl phenyl phosphate ester.
[0019] The amount of triaryl phosphate (B) used in the present
invention is preferably from 0.05 to 10% by weight, more preferably
from 0.05 to 5% weight and most preferably from 0.1 to 2% by weight
with respect to the total amount of lubricating oil base oil.
[0020] If less than 0.05% by weight of (B) is added, sufficient
lubricating performance may not be achieved, whereas if more than
10% by weight of (B) is added, the lubricating performance reaches
saturation and there may be a deterioration in thermal oxidation
stability and hydrolysis stability, which is undesirable.
[0021] In a preferred embodiment of the present invention, the
lubricating oil composition exhibits wear corresponding to no more
than 150 mg, which meets DIN 51524 (Part 2) standard, in a "Vickers
V104 C" vane pump test (according to IP 281).
[0022] In another preferred embodiment of the present invention,
the lubricating oil composition exhibits vane wear corresponding to
no more than 15 mg and ring wear corresponding to no more than 75
mg, which meets "Vickers" standard M-2950-S, in a "Vickers 35VQ25A"
vane pump test (according to "Vickers" M-2950-S).
[0023] In yet another preferred embodiment of the present
invention, the lubricating oil composition exhibits vane wear
corresponding to no more than 10 mg and ring wear corresponding to
no more than 50 mg, which meets "General Motors" Standard
LS-2LH.03.04.06, in a "Vickers 35VQ25A" vane pump test (according
to "Vickers" M-2950-S).
[0024] The lubricating oil composition according to the present
invention may be used as a hydraulic oil composition, a compressor
oil composition, a turbine oil composition, a bearing oil
composition, and/or a gear oil composition.
[0025] There are no particular limitations regarding the base oil
in the lubricating oil composition of the present invention.
Preferably, said base oil is petroleum-based, synthetic
hydrocarbon-based and/or ester-based.
[0026] The preferred physical properties of the base oil are as
follows:
[0027] a kinematic viscosity of from 2 to 680 mm.sup.2/s
(40.degree. C.), preferably from 5 to 320 mm.sup.2/s (40.degree.
C.) and more preferably from 8 to 220 mm.sup.2/s (40.degree.
C.);
[0028] a total sulphur content (% by weight) of from 0 to 1% and
preferably from 0 to 0.3%;
[0029] a total nitrogen content (weight ppm) of from 0 to 100 ppm
and preferably from 0 to 30 ppm; and/or
[0030] an aniline point of from 80 to 130.degree. C. and preferably
from 100 to 125.degree. C.
[0031] Petroleum-based lubricating oil base oils which can be used
in the present invention include solvent purified base oil,
hydrogenation purified base oil and highly hydrocracked base oil.
Such base oils can be used individually or as mixtures.
[0032] Highly hydrocracked base oil is a base oil having a
viscosity index of at least 130 (typically from 145 to 155). Said
base oil can be obtained by taking a starting material wax (slack
wax) which has been separated by solvent dewaxing, and
hydrogenating said wax in the presence of a catalyst (catalytic
degradation) to convert linear paraffin to branched paraffin.
Alternatively, said base oil can be obtained by taking as starting
material the hydrogen and carbon monoxide obtained by subjecting
natural gas (methane or the like) to the gas formation process
(partial oxidation), then subjecting said starting material to
Fischer-Tropsch polymerisation to yield heavy linear paraffin, and
then modifying said heavy linear paraffin to catalytic degradation
as described above.
[0033] The synthetic hydrocarbon-based base oil used in the present
invention can be an olefin oligomer obtained by homopolymerizing or
copolymerizing monomer chosen from linear or branched olefinic
hydrocarbons of from 3 to 15, preferably from 4 to 12, carbon
atoms.
[0034] In the present invention, petroleum-based base oil or
synthetic hydrocarbon-based base oil can be used individually, or
in mixtures thereof.
[0035] Triaryl phosphate esters have long been known as anti-wear
agents for use under relatively mild conditions, and, as disclosed
in U.S. Pat. No. 5,922,657 (corresponding to Japanese Unexamined
Patent Application Number H10-67993), .beta.-dithiophosphorylated
propionic acid is known to improve extreme pressure performance and
prevent gear seizure.
[0036] However, in the present invention, the anti-wear properties
under severe high pressure/high load conditions can be improved to
equivalent to or better than those achieved when
.beta.-dithiophosphorylated propionic acid is used alone, by the
combined use of the abovementioned anti-wear component
triarylphosphate ester.
[0037] In addition to the abovementioned indispensable components,
various other commonly used additives may also be added if
necessary in the present invention in order to further improve
performance.
[0038] Thus, it is possible to add commonly known lubricating oil
additives such as antioxidant, rust preventer, metal deactivator,
detergent dispersant, anti-wear agent, extreme-pressure agent,
friction regulator, flow point depressor, viscosity index improver,
anti-emulsification agent and defoamer.
[0039] For example, examples of amine-based antioxidants include
dialkyldiphenylamines such as p,p'-dioctyldiphenylamine
(manufactured by Seiko Kagaku under the trade designation "Nonflex
OD-3"), p,p'-di-.alpha.-methylbenzyldiphenylamine and
N-p-butylphenyl-N-p'-octylp- henylamine; monoalkyldiphenylamines
such as mono-t-butyldiphenylamine and monooctyldiphenylamines;
bis(dialkylphenyl)amines such as di(2,4-diethylphenyl)amine and
di(2-ethyl-4-nonylphenyl)amine; alkylphenyl-1-naphthylamines such
as octylphenyl-1-naphthylamine and
N-t-dodecylphenyl-1-naphthylamine; arylnaphthylamines such as
1-naphthylamine, phenyl-1-naphthylamine, phenyl-2-naphthylamine,
N-hexylphenyl-2-naphthylamine and N-octylphenyl-2-naphthylamine;
phenylenediamines such as N,N'-diisopropyl-p-phenylenediamine and
N,N'-diphenyl-p-phenylenediamine; and phenothiazines such as
phenothiazine (manufactured by Hodogaya Kagaku: Phenothiazine) and
3,7-dioctylphenothiazine.
[0040] Examples of sulphur-based antioxidants include dialkyl
sulphates such as didodecyl sulphate and dioctadecyl sulphate,
thiodipropionic acid esters such as didodecyl thiodipropionate,
dioctadecyl thiodipropionate, dimyristyl thiodipropionate and
dodecyloctadecyl thiodipropionate, and 2-mercaptobenzimidazole.
[0041] Examples of phenol-based antioxidants include
2,6-di-t-butyl-4-alkylphenols such as 2-t-butylphenol,
2-t-butyl-4-methylphenol, 2-t-butyl-5-methylphenol,
2,4-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol,
2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol,
2,5-di-t-butylhydroquinone (manufactured by Kawaguchi Kagaku under
the trade designation "Antage DBH"), 2,6-di-t-butylphenol,
2,6-di-t-butyl-4-methoxylphenol and 2,6-di-t-butyl-4-ethylphenol;
2,6-di-t-butyl-4-alkoxyphenols such as
2,6-di-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-ethoxyphenol;
alkyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionates such as
3,5-di-t-butyl-4-hydroxybenzylmercaptooctyl acetate,
n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate
(manufactured by Yoshitomi Seiyaku under the trade designation
"Yoshinox SS"), n-dodecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate and 2'-ethylhexyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate; 2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol;
2,2'-methylenebis(4-alkyl-- 6-t-butylphenol)s such as
2,2'-methylenebis(4-methyl-6-t-butylphenol) (manufactured by
Kawaguchi Kagaku under the trade designation "Antage W-400") and
2,2'-methylenebis(4-ethyl-6-t-butylphenol) (manufactured by
Kawaguchi Kagaku under the trade designation "Antage W-500");
bisphenols such as 4,4'-butylidenebis(3-methyl-6-t-butylphenol)
(manufactured by Kawaguchi Kagaku under the trade designation
"Antage W-300"), 4,4'-methylenebis(2,6-di-t-butylphenol)
(manufactured by Laporte Performance Chemicals under the trade
designation "Ionox 220AH"), 4,4'-bis(2,6-di-t-butylphenol),
2,2-(di-p-hydroxyphenyl)propane (bisphenol A),
2,2-bis(3,5-di-t-butyl-4-hydroxyphenyl)propane,
4,4'-cyclo-hexylidenebis(2,6-t-butylphenol), hexamethylene glycol
bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by
Ciba Speciality Chemicals under trade designation "Irganox L109"),
triethylene glycol
bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate] (manufactured
by Yoshitomi Seiyaku under the trade designation "Tominox 917"),
2,2'-thio-[diethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]
(manufactured by Ciba Speciality Chemicals under the trade
designation "Irganox L115"),
3,9-bis{1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylp-
henyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane
(manufactured by Sumitomo Kagaku under the trade designation
"Sumilyzer GA80"), 4,4'-thiobis(3-methyl-6-t-butylphenol)
(manufactured by Kawaguchi Kagaku under the trade designation
"Antage RC") and 2,2'-thiobis(4,6-di-t-butyl)resorcin; polyphenols
such as
tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane
(manufactured by Ciba Speciality Chemicals under the trade
designation "Irganox L101"),
1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane (manufactured
by Yoshitomi Seiyaku under the trade designation "Yoshinox 930"),
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene
(manufactured by Ciba Speciality Chemicals under the trade
designation "Irganox 1330"),
bis-[3,3'-bis-(4'-hydroxy-3'-t-butyl-phenyl)butyric acid]glycol
ester, 2-(3',5'-di-t-butyl-4-hydroxyphenyl)methyl-4-(2",4"-di-
-t-butyl-3"-hydroxyphenyl)methyl-6-t-butylphenol and
2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl)-4-methylphenol; and
phenol-aldehyde condensates such as the condensate of
p-t-butylphenol and formaldehyde and the condensate of
p-t-butylphenol and acetaldehyde.
[0042] Examples of phosphorous-based antioxidants include triaryl
phosphites such as triphenyl phosphite and tricresyl phosphite,
trialkyl phosphites such as trioctadecyl phosphite and tridecyl
phosphite, and tridodecyl trithiophosphite.
[0043] These antioxidants can be used individually, or a plurality
can be used in combination, and the amount added thereof may
conveniently be from 0.01 to 2.0 parts by weight per 100 parts by
weight of base oil.
[0044] Examples of metal deactivators which can be used in the
lubricant composition of the present invention include
benzotriazole, and benzotriazole derivatives, for example,
4-alkylbenzotriazoles such as 4-methylbenzenotriazole and
4-ethylbenzotriazole, 5-alkylbenzotriazoles such as
5-methylbenzotriazole and 5-ethylbenzotriazole,
1-alkylbenzotriazoles such as
1-dioctylaminomethyl-2,3-benzotriazole and 1-alkyltolutriazoles
such as 1-dioctylaminomethyl-2,3-tolutriazole; benzimidazole, and
benzimidazole derivatives, for example,
2-(alkyldithio)benzimidazoles such as 2-(octyldithio)benzimidazole,
2-(decyldithio)benzimidazole and 2-(dodecyldithio)benzimidazole,
and 2-(alkyldithio)toluimidazoles such as
2-(octyldithio)toluimidazole, 2-decyldithio)toluimidazole and
2-(dodecyldithio)toluimidazole; indazole, and indazole derivatives,
for example, toluindazoles such as 4-alkyl-indazole and
5-alkyl-indazole; benzothiazole, and benzothiazole derivatives, for
example, 2-(alkyldithio)benzothiazoles such as
2-mercaptobenzothiazole derivative (manufactured by Chiyoda Kagaku
under the trade designation "Thiolite B-3100"),
2-(hexyldithio)-benzothiazole and 2-(octyldithio)benzothiazole,
2-(alkyldithio)toluthiazoles such as 2-(hexyldithio)-toluthiazole
and 2-(octyldithio)-toluthiazole,
2-(N,N-dialkyldithiocarbamyl)benzothiazoles such as
2-(N,N-diethyldithiocarbamyl)benzothiazole,
2-(N,N-dibutyldithiocarbamyl)- benzothiazole and
2-(N,N-dihexyldithiocarbamyl)benzothiazole, and
2-(N,N-dialkyldithiocarbamyl)toluthiazoles such as
2-(N,N-diethyldithiocarbamyl)toluthiazole,
2-(N,N-dibutyl-dithiocarbamy)t- oluthiazole and
2-(N,N-dihexyl-dithiocarbamyl)toluthiazole; benzoxazole
derivatives, for example, 2-(alkyldithio)benzoxazoles such as
2-(octyldithio)benzoxazole, 2-(decyldithio)benzoxazole and
2-(dodecyldithio)benzoxazole, and 2-(alkyldithio)toluoxazoles such
as 2-(octyldithio)toluoxazole, 2-(decyldithio)toluoxazole and
2-(dodecyldithio)toluoxazole; thiadiazole derivatives, for example,
2,5-bis(alkyldithio)-1,3,4-thiadiazoles such as
2,5-bis(heptyldithio)-1,3- ,4-thiadiazole,
2,5-bis(nonyldithio)-1,3,4-thiazidazole,
2,5-bis(dodecyldithio)-1,3,4-thiadiazole and
2,5-bis(octadecyldithio)-1,3- ,4-thiadiazole,
2,5-bis(N,N-dialkyldithiocarbamyl)-1,3,4-thiadiazoles such as
2,5-bis(N,N-diethyldithiocarbamyl)-1,3,4-thiadiazole,
2,5-bis(N,N-dibutyldithiocarbamyl)-1,3,4-thiadiazole and
2,5-bis(N,N-dioctyldithiocarbamyl)-1,3,4-thiadiazole, and
2-N,N-dialkyldithiocarbamyl-5-mercapto-1,3,4-thiadiazoles such as
2-N,N-dibutyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole and
2-N,N-dioctyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole; and
triazole derivatives, for example, 1-alkyl-2,4-triazoles such as
1-dioctylaminomethyl-2,4-triazole.
[0045] These metal deactivators can be used individually, or a
plurality can be used in combination, and the amount added thereof
may conveniently be from 0.005 to 0.5 parts by weight per 100 parts
by weight of base oil.
[0046] Examples of defoamers which can be used include
organosilicates such as dimethylpolysiloxane, diethyl silicate and
fluorosilicone, and non-silicone defoamers such as polyalkyl
acrylates. These can be used individually or a plurality can be
used in combination, and the amount added thereof may conveniently
be from 0.0001 to 0.1 parts by weight per 100 parts by weight of
base oil.
[0047] Examples of viscosity index improvers include
non-dispersant-type viscosity index improvers for example,
polymethacrylates and olefin copolymers such as ethylene/propylene
copolymer and styrene/diene copolymer, and dispersion-type
viscosity index improvers such as those obtained by copolymerizing
these with nitrogen-containing monomers. The amount added thereof
may conveniently be from 0.05 to 20 parts by weight per 100 parts
by weight of base oil.
[0048] Examples of flow point depressors include
polymethacrylate-based polymers. The amount added thereof may
conveniently be from 0.01 to 5 parts by weight per 100 parts by
weight of base oil.
[0049] Examples of detergent dispersants include metal-based based
detergents, for example, neutral or basic alkaline earth metal
sulphonates, alkaline earth metal phenates and alkaline earth metal
salicylates, and ashless dispersants, for example modified products
obtained from alkenyl succinate imides, alkenyl succinate esters or
boron compounds, sulphur compounds etc. thereof. These can be used
individually or a plurality can be used in combination, and the
amount added thereof may conveniently be from 0.01 to 1 parts by
weight per 100 parts by weight of base oil.
[0050] Examples of extreme-pressure agents and friction regulators
include sulphur-based extreme-pressure agents such as dialkyl
sulphides, dibenzyl sulphide, dialkyl polysulphides, dibenzyl
disulphide, alkyl mercaptans, dibenzothiophene and
2,2'-dithiobis(benzothiazole); phosphorous-based extreme-pressure
agents such as trialkyl phosphates, trialkyl phosphonates, trialkyl
phosphites, triaryl phosphites, dialkyl hydrogen phosphites,
trialkyl trithiophosphites and triaryl phosphorothioates; aliphatic
friction regulators such as fatty acid amides and fatty acid
esters; amine-based friction regulators such as primary to tertiary
alkylamines and alkylene oxide adducts of alkyl amines; and
extreme-pressure agents such as zinc alkyl dithiophosphates. These
extreme-pressure agents and friction regulators can be used
individually, or a plurality can be used in combination, and the
amount added thereof may conveniently be in the range from 0.05 to
5.0 parts by weight per 100 parts by weight of base oil.
[0051] Examples of rust preventers which can be used include
N-alkylsarcosinic acids, alkylate phenoxy acetates, imidazolines,
"KX1031" manufactured by King Industry and alkaline earth metal
salts thereof and amine salts thereof, the N-acyl-N-alkoxyalkyl
asparginate esters disclosed in Japanese Unexamined Patent
Application Number H6-200268, the alkaline earth metal salts of
phosphate esters disclosed in EP-A-0801116 and alkenyl succinate
ester-based rust preventers. These rust preventers can be used
individually or a plurality can be used in combination, and the
amount added may conveniently be in the range of from 0.005 to 1.0
parts by weight can be used per 100 parts by weight of base
oil.
[0052] Examples of anti-emulsifying agents (used to break up
emulsions to allow separation into two liquid layers) include
commonly known substances which are usually used as lubricating oil
additives, for example, polyalkylene glycol-based nonionic
surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene
alkyl phenyl ethers and polyoxyethylene alkyl naphthyl ethers. The
amount added may conveniently be in the range of from 0.0005 to 0.5
parts by weight per 100 parts by weight of base oil.
[0053] It is particularly appropriate to use the lubricating oil
composition of the present invention as a hydraulic oil composition
as described above. However, said lubricating oil composition can
also be used in other ways, for example, as a compressor oil
composition, turbine oil composition, bearing oil composition or
gear oil composition.
[0054] The present invention will now be described with reference
to the following Examples, which are not intended to limit the
scope of the present invention in any way.
EXAMPLES
[0055] The present invention is described specifically below by
means of hydraulic oil working examples.
[0056] Hydrogenation-purified base oil having a kinematic viscosity
of 31 mm.sup.2/s at 40.degree. C. was used as the base oil, and the
components shown below were added to yield base lubricating oil
compositions.
[0057] The anti-wear agents shown in Tables 2, 3 and 4 were added
to this base lubricating oil composition A (Table 1) to yield test
oil having a kinematic viscosity of 32 mm.sup.2/s at 40.degree.
C.
[0058] The amount of the various additive components in the test
oils of Working Examples 1 and 2 and Comparative Examples 1 to 10
are given as parts by weight with respect to the test oil.
1TABLE 1 Base lubricating oil composition A Hydrogenation-purified
base oil: 99.15 parts by Kinematic viscosity 31 mm.sup.2/s @
40.degree. C. weight Antioxidant: (manufactured by Echiru 0.5 parts
by under the trade designation "Hitec weight 4733") Metal
deactivator: (manufactured by 0.05 parts by Ciba Speciality
Chemicals under the weight trade designation "Irgamet 39") Flow
point depressor: (manufactured 0.3 parts by by Toho Kagaku Kogyo
under the trade weight designation "Lubran 141")
[0059] Inventive lubricating oil composition (Working Examples 1
and 2) and conventional anti-wear compositions which do not
comprise the inventive composition, by way of comparison,
(Comparative Examples 1 to 6) were prepared according to the
proportions shown in Tables 2 and 3.
[0060] The working example and comparative example compositions
were subjected to vane pump tests as described below and the
results are shown in Table 5.
[0061] Also, for comparison, the same performance appraisal tests
were performed on commercial products obtained using the zinc-free
ashless anti-wear hydraulic oils shown in Table 4 (Comparative
Examples 7 and 8), and these results are also shown in Table 5. It
should be noted that the methods for the performance tests
performed on the working examples and comparative examples were as
follows.
[0062] IP 281 "Vickers V104C" Vane Pump Test
[0063] In order to appraise the anti-wear performance of the test
oil in a vane pump, the pump test was formed for 250 h at a
pressure of 13.73 MPa (140 kgf/cm.sup.2), 1500 rpm, oil temperature
65.degree. C. using a "Vickers V104C" pump, and the wear of the
vane and ring were measured after the test. The DIN 51524 (part 2)
criterion for anti-wear hydraulic oil is that the total amount of
wear on the vane and ring be equivalent to no more than 150 mg.
[0064] "Vickers 35VQ-25A" Vane Pump Test
[0065] In order to appraise the anti-wear performance of the test
oil in a vane pump at high pressure, high speed and high
temperature, the pump test was performed for 50 h at a pressure of
20.59 MPa (210 kgf/cm.sup.2), 2400 rpm, oil temperature 93.degree.
C. using a "Vickers 35VQ-25A" pump, and the wear on the vane and
ring was measured after the test. The "Vickers" M-2950-S criterion
is that the vane wear be equivalent to no more than 15 mg and the
ring wear be equivalent to no more than 75 mg.
[0066] The "General Motors" LS-2 LH.03.04.06 criteria are stricter:
vane wear corresponding to no more than 10 mg and ring wear
corresponding to no more than 50 mg.
2TABLE 2 Compar- Comparative Comparative Comparative ative Example
Example 1 Example 2 Example 3 Example 4 Base lubricating 100 99.5
99.0 99.0 oil composition A (% by weight) Component 1 -- -- -- --
.beta.-dithiophos- phorylated propionic acid Component 2 -- 0.5 1.0
-- Trialkyl phenyl phosphate ester Triphenyl -- -- -- 1.0
phosphoro-thioate
[0067]
3TABLE 3 Compar- Working Working Comparative ative Example Example
1 Example 2 Example 5 Example 6 Base lubricating 99.18 99.18 99.975
99.48 oil composition A(% by weight) Component 1 0.02 -- 0.025 0.02
.beta.-dithiophos- phorylated propionic acid Component 2 0.8 0.8 --
-- Trialkyl phenyl phosphate ester Component 3 -- 0.02 -- --
.beta.-dithiophos- phorylated propionic acid Triphenylphosphoro- --
-- -- 0.5 thioate
[0068] In Tables 2 and 3 above, Component 1 is a
.beta.-dithiophosphorylat- ed propionic acid represented by general
formula (1) in which R.sup.1 is an isobutyl group and R.sup.2 is a
methyl group.
[0069] Component 2 in Tables 2 and 3 is a triarylphosphate sold
under the trade designation "Reofos 65" ex. Ajinomoto.
[0070] Component 3 is a .beta.-dithiophosphorylated propionic acid
represented by the general formula (1) in which R.sup.1 is an
isobutyl group and R.sup.2 is a hydrogen group.
[0071] Triphenylphosphorothioate in Table 3 is that sold under the
trade designation "Irgalube TPPT" ex. Ciba.
4 TABLE 4 Commercial anti-wear hydraulic Comparative Comparative
oil Example 7 Example 8 Phosphorus content 0.163 0.092 (% by
weight) Sulphur content -- 0.020 (% by weight) Kinematic viscosity
cSt 40.degree. C. 30.6 30.4 Kinematic viscosity cSt 100.degree. C.
5.46 5.29 Note: All commercial anti-wear hydraulic oils used were
zinc free.
[0072]
5TABLE 5 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Working
Working Example Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex.
1 Ex. 2 IP 281 "Vickers V104C" Vane Pump Test vane wear (mg) 49 37
8 6 3 8 45 9 2 3 Ring wear (mg) 415 213 65 34 3 159 40 36 3 1 Total
wear (mg) 464 250 73 40 6 167 85 45 5 4 "Vickers 35VQ25A" Vane Pump
Test vane wear (mg) -- -- 38 8 3 -- 22 39 2 2 Ring wear (mg) -- --
606 108 7 -- 351 755 3 2 Total wear (mg) -- -- 644 116 10 -- 373
794 5 4
[0073] Comparative Examples 1 and 2 did not exhibit adequate
anti-wear properties in the "Vickers V104C" vane pump test and did
not have the anti-wear properties required to pass German Standard
DIN 51524 (part 2). Comparative Examples 3 and 4 did pass German
Standard DIN 51524 (part 2) in the "Vickers V104C" vane pump test,
but did not exhibit adequate anti-wear properties in the "Vickers
35VQ25A" vane pump test and did not pass the "Vickers" M-2950-S
standard or "General Motors" LS-2 LH.03.04.06 standard. Comparative
Examples 7 and 8 exhibited anti-wear properties sufficient to pass
German Standard DIN 51524 (part 2) in the V104C vane pump test, but
their anti-wear properties were not sufficient to pass the
"Vickers" M-2950-S standard or the "General Motors"
LS-2-LH.03.04.06 standard.
[0074] As is clear from the compositions shown in Table 3 and the
results shown in Table 5, the lubricating oil composition according
to the present invention (Working Examples 1 and 2) have excellent
anti-wear properties sufficient to pass German Standard DIN 51524
(Part 2), "Vickers" M-2950-S standard and "General Motors" LS-2
LH.03.04.06 standard, in vane pump tests "Vickers" V104C and
35VQ25A, and their lubricating oil performance is sufficient for
use as a hydraulic oil in high-pressure applications. Comparative
Example 5 shows increased total wear in both tests when compared to
Working Examples 1 and 2.
[0075] However, when the additive combination of the present
invention is not used (comparative examples), and in the case of
commercial zinc-free hydraulic oils and zinc-based hydraulic oils,
the anti-wear properties and extreme-pressure performance are both
considerably poorer and there are problems when these oils are used
as lubricating oils for modern industrial machines which have been
miniaturized and work at high speeds, high pressures and high
precision.
Comparative Examples 9 and 10
[0076] Comparative Examples 9 and 10 were performed in order to see
whether the thermal oxidative stability is better when R.sup.2 in
the .beta.-dithiophosphorylated propionic acid is hydrogen or when
it is a methyl group. The composition and results for Comparative
Examples 9 and 10 are shown in Table 6.
[0077] The thermal oxidative stability test was performed as
follows: 200 ml of test oils of Comparative Examples 9 and 10,
obtained by combining .beta.-dithiophosphorylated propionic acid
and antioxidant and rust preventer, were independently introduced
into 250 ml beakers, a steel sample and copper sample of diameter
0.6 mm and length 7.6 mm, which had been polished using #240
alumina polishing paper, washed and dried, were intersected and the
test oils were applied thereto, and the test oils were subjected to
thermal oxidative deterioration for 336 hours in a 140.degree. C.
oven, and after the test the test oils were suction-filtered using
a 0.8 .mu.m hole diameter filter and the amount of sludge obtained,
the external appearance of the copper sample and steel sample and
the colour of the test oil (ASTM D1500) were measured.
6 TABLE 6 Comparative Comparative Example 9 Example 10 Hydrogenated
purified base oil B *1 99.74 99.74 Antioxidant *2 0.10 0.10 Rust
preventer *3 0.01 0.01 .beta.-dithiophosphorylated propionic acid
0.15 -- R.sup.1: isobutyl R.sup.2: hydrogen
.beta.-dithiophosphorylated propionic acid -- 0.15 R.sup.1:
isobutyl R.sup.2: methyl Colour of test oil L 0.5 L 0.5 Thermal
oxidation stability test L 5.0 L 4.5 Colour of oil Appearance of
copper No rust No rust Appearance of steel No change No change
Amount of sludge (mg) 10.3 0.0 *1 Hydrogenated purified base oil B:
kinematic viscosity 32 Cst (at 40.degree. C.), Sulphur content no
greater than 5 ppm, viscosity index 110 *2 Antioxidant: under the
trade designation "Irganox L135": manufactured by Ciba Speciality
Chemicals *3 Rust preventer: under the trade designation "IRGAMET
39", manufacture by Ciba Speciality Chemicals
[0078] As is clear from the results of the thermal oxidative
stability tests shown in Table 6, the compound of Comparative
Example 10 in which one of the hydrogen atoms on the .alpha.-carbon
of the .beta.-dithiophosphorylated propionic acid has been
substituted by an alkyl group, undergoes less change in colour and
produces less sludge, that is, is more stable, than the compound of
Comparative Example 9 in which there is no alkyl substitution of
the hydrogen atoms on the .alpha.-carbon. If there are too many
carbon atoms in the alkyl group substitutions on the
.alpha.-carbon, anti-wear properties deteriorate and so in order to
achieve both thermal oxidative stability and anti-wear properties,
the alkyl group substituent is most preferably a methyl group.
[0079] Advantages of the Present Invention
[0080] Lubricating oil compositions of the present invention
contain no, or almost no, ash-forming substances such as zinc
dialkyl dithiophosphates, in view of environmental and safety
considerations; the resulting anti-wear lubricating oil
compositions exhibit excellent anti-wear with respect to various
machine elements even when used under severe high pressure, high
speed and high load conditions. Accordingly, the lubricating oil
compositions of the present invention are highly effective in the
provision of lubricating oil which can guarantee the reliability of
equipment over long periods, in response to the recently developed
high speed, high pressure and high precision industrial
machines.
* * * * *