Note: Descriptions are shown in the official language in which they were submitted.
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LUBRICANT OIL ADDITIVE COMPOSITIONS
FIELD OF THE INVENTION
[001] The invention relates to lubricant oil additive compositions and
lubricating oil
compositions containing the same. More particularly, this invention relates to
combinations of
hindered phenol.ic antioxidants, boronated hindered phenolic antioxidants,
alkylated
diphenylamines and organomolybdenum compounds useful as lubricant oil
compositions and
lubricating oil additive compositions.
DESCRIPTION OF RELATED ART
[002] Hindered phenolic and boronated hindered phenolics are well known in the
art,
including large molecular phenolics incorporating the moiety, 2,6-di-tert-
butylphenol, and the
lil{ee See, for example, the following US and foreign patents: US 4,927,553;
US 3,356,707; tJS
3,509,054; US 3,347,793; US 3,014,061; US 3,359,298; US 2,813,830; US
2,462,616; GB
864,840; US 5,698,499; US 5,252,237; US RE 32,295; US 4,547,302; US 3,211,652;
and US
2,807,653
[003] The use of alkylated diphenylamine as an antioxidant additive in
lubricating oil
formulations is also well known in the art. See, for example, the following US
patents: US
5,620,948; US 5,595,964; US 5,569,644; US 4,857,214; US 4,455,243; and US
5,759,965.
[004] There are many examples in the patent literature showing the use of
molybdenum
additives as antioxidants, deposit control additives, anti-wear additives and
friction modifiers.
See, for example, the following US and foreign patents: US 5,840,672; US
5,814,587; US
4,529,526; WO 95/07966; US 5,650,381; US 4,812,246; US 5,458,807; WO 95/07964;
US
5,880,073; US 5,658,862; US 5,696,065; WO 95/07963; US 5,665,684; US
4,360,438; US
5,736,491; WO 95/27022; US 5,786,307; US 4,501,678; US 5,688,748; EP 0 447 916
Al; US
5,807,813; US 4,692,256; US 5,605,880; WO 95/07962; US 5,837,657; US
4,832,867; US
4,705,641; EP 0 768 366 Al; US 6,103,674; US 6,010,987; US 6,110,878; EP 1 136
496 Al; US
6,150,309; US 6,232,276; US 6,306,802; EP 1 136 497 Al; US 5,888,945; US
6,187,723; US
6,117,826; US 6,103,674; US 6,063,741; US 6,017,858; US 5,994,277; and US
6,174,841
~
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SUMMARY OF THE INVENTION
[005] The present invention generally provides a lubricant oil composition
having
improved oxidative stability, the composition comprising at least one hindered
phenolic
antioxidant, at least one mono-boronated hindered phenolic antioxidant, at
least one di-
boronated hindered phenolic antioxidant, at least one alkylated diphenylamine,
and at least one
organomolybdenum compound. The invention also provides a lubricating oil
additive
concentrate composition that imparts synergistic oxidative stability to a
lubricant oil upon its
addition, the concentrate composition comprising at least one hindered
phenolic antioxidant, at
least one mono-boronated hindered phenolic antioxidant, at least one di-
boronated hindered
phenolic antioxidant, at least one alkylated diphenylamine, and at least one
organomolybdenum
compound. Further, the concentrate compositions of the present invention may
also be prepared
with a high concentration of hindered phenolic antioxidants without
deleterious effects on
viscosity or lubricant solubility.
[0061 The synergistic improvement of oxidative stability in lubricant oil
compositions and
lubricating oil additive concentrate compositions comprising at least one
hindered phenolic
antioxidant, at least one mono-boronated hindered phenolic antioxidant, at
least one di-
boronated hindered phenolic antioxidant, and at least one alkylated
diphenylamine is disclosed
in concurrently filed, commonly owned US Provisional Application 60/758,754
filed on January
13, 2006, and in PCT application number PCT/US2007/060489 that claims priority
to US
Provisional Application 60/758,754, both of which are hereby incorporated by
reference in their
entirety to the extent allowed by applicable law. The present invention
improves upon the
disclosure of US Provisional Application 60/758,754 such that lubricant oil
compositions and
lubricating oil additive concentrate compositions comprising at least one
hindered phenolic
antioxidant, at least one mono-boronated hindered phenolic antioxidant, at
least one di-
boronated hindered phenolic antioxidant, at least one alkylated diphenylamine,
and at least one
organomolybdenum compound exhibits improved oxidative stability compared to
conventional
formulationse
[007] In one aspect, a lubricant oil or lubricating oil additive concentrate
composition
comprising: (a) 4,4'-methylenebis(2,6-di-tert-butylphenol), (b) 4,4 -
methylenebis(2,6-di-tert-
butylphenol)-mono-(di-alkyl orthoborate), (c) 4,4'-methylenebis(2,6-di-tert-
butylphenol)-di-(di-
alkyl orthoborate), (d) an alkylated diphenylamine, and (e) an
organomolybdenum compound, is
an effective antioxidant combination for use in lubricants.
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[008] In another aspect, a lubricant oil or lubricating oil additive
concentrate composition
comprising: (a) a hindered phenolic antioxidant, (b) either a single or
multiple ortho-borate ester,
or combinations thereof, derived from a hindered phenolic antioxidant, wherein
the boron is
attached to the hindered phenolic oxygen, (c) an alkylated diphenylamine, and
(d) an
organomolybdenum compound, is an effective antioxidant combination for use in
lubricants.
BRIEF DESCRIPTION OF THE FIGURE
[0091 Figure 1 shows graphical results from Example A.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Hindered phenolics suitable for use in the compositions of the present
invention
include phenolics incorporating the 2,6-di-tert-butylphenol moiety. A suitable
hindered
phenolic, which is commercially sold by Albemarle CorporationTM under the
trade name
Ethanox 702, is 4,4'methylenebis(2,6-di-tert-butylphenol), hereinafter
referred to as MBDTBP,
having the structure of Structure I below:
H3C H3C Structure I
CH3 CH3
H3C H3C
HO CH2 CH
H3C H3C
CH3 CH3
H3C H3C
[0011] Other suitable hindered phenolics include, 2,4-di-tert-butylphenol, 2,6-
di-tert-
butylphenol, 6-tert-butyl-ortho-cresol, 2,6-di-isopropylphenol, 2,4-di-sec-
butylphenol, higher
molecular weight hindered phenolic antioxidants derived synthetically from 2,4-
di-tert-
butylphenol, 2,6-di-tert-butylphenol, 6-tert-butyl-ortho-cresol, 2,6-di-
isopropylphenol, or 2,4-di-
sec-butylphenol, butylated hydroxy toluene (BHT), and the like.
[0012] The amount of hindered phenolic present in the compositions of the
invention ranges
from about 1 to about 50 weight percent of the total concentration of hindered
phenolic,
boronated hindered phenolic, and alkylated diphenylamine. In additional
aspects the amount of
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hindered phenolic present in the compositions of the invention ranges from
about 1 to about 40
weight percent, about 1 to about 30 weight percent, about 1 to about 25 weight
percent, about 1
to about 20 weight percent, and about 1 to about 15 weight percent of the
total concentration of
hindered phenolic, boronated hindered phenolic, and alkylated diphenylamine,
[00131 The mono- and di-boronated hindered phenolics suitable for use in the
compositions
of the present invention are derived from the hindered phenolics described
above by reaction
with tri-alkyl orthoborates. One such process is disclosed in US 4,927,553. In
one aspect,
suitable mono- and di-boronated hindered phenolics have the structures of
Structures II and III
below:
H3G H3C Structure II
GHg CH3
H3C H3C
F21--0 \B C,iH2 OH
\ /
R2 0 / F-V3C'; HgC
CHg CF13
H3C H3C
H3C H3C
L~v+ cH3 ~H3 u!~ Structure III
i 13Li i 13Li
FZ1 O\ / R3
B 0 C"2 \ / B~
R2 O e R4
h93C HgG
CFi3 CH3
Fi3C H3C
wherein Ri, R2, R3, and R4 are independently selected from the group
consisting of linear,
branched and cyclic C, to Cg alkyl groups. Examples of such groups include,
but are not limited
to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, n-
pentyl, 2-methylbutyl, 3-
methylbutyl, 2-methyl-2-butyl, 3-methyl-2-butyl, isopentyl, n-hexyl,
cyclopentyl, cyclohexyl, 2-
ethylbutyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 3-methyl-2-pentyl,
4-methyl-2-
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pentyl, 3-methyl-3-pentyl, 3,3-dimethylbutyl, 3,3-dimethyl-2-butyl, 2,3-
dimethyl-2-butyl, 2-
methyl-2-hexyl, 2,2-dimethyl-3-pentyl, 2-heptyl, 3-heptyl, 2-methyl-3-hexyl, 3-
ethyl-3-pentyl,
2,3-dimethyl-3-pentyl, 2,4-dimethyl-3-pentyl, 5-methyl-2-hexyl, 4,4-dimethyl-2-
pentyl, 5-
methylhexyl, n-heptyl, n-octyl, iso-octyl, 2-ethylhexyl, 2-propylpentyl, 2-
octyl, 3-octyl, 2,44-
triinethylpentyl, 4-methyl-3-heptyl and 6-methyl-2-heptyl.
[0014] Other mono- and di-boronated hindered phenolics may be derived from
reacting the
specific hindered phenolics described above, or mixtures of hindered
phenolics, with tri-alkyl
orthoborates,
[0015] The combined total of mono- and di-boronated hindered phenolics present
in the
compositions of the invention ranges from about 10 to about 80 weight percent
of the total
concentration of hindered phenolic, boronated hindered phenolic, and alkylated
diphenylamine.
The ratio of mono-boronated hindered phenolic to di-boronated hindered
phenolic may vary
from about 0.01:1 to about 1 D0.01. The amount of mono-boronated hindered
phenolic can be
approximately equal to or greater than that of di-boronated hindered phenolic.
[0016] The amount of MBDTBP in conventional lubricant oil additive concentrate
compositions has been limited by its solubility to about 10 wt% of the total
additive concentrate.
However, the present invention provides a method for increasing the
concentration of hindered
phenolic antioxidant in the lubricant oil additive concentrate composition to
be increased to as
high as about 50 wt% by including boronated hindered phenolic antioxidants in
the lubricant oil
additive concentrate composition.
[0017] The alkylated diphenylamines suitable for use in the compositions of
the present
invention are prepared from diphenylamine by reaction with olefins. One
particularly useful
method of preparing alkylated diphenylamines is described in US Patent
Publication US-2006-
0276677-Al (which related to US 11/442856 filed 30 May 2006, which claims
priority to US
Provisional Patent Application 60/687,182 filed on June 2, 2005 and to US
Provisional Patent
Application 60/717322 filed on Sept. 14, 2005), which US Patent Publication is
incorporated in
its entirety by reference herein to the extent allowed by applicable law. Both
mono- and di-
alkylated diphenylamines may be employed, either alone are in combination, and
have the
structures shown in Structures IV and V below:
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Structure IV
R1 /NH\
Structure V
R NH R3
wherein R1, R2 and R3 are independently selected from the group consisting of
linear, branched
and cyclic C4 to C32 alkyl groups. Examples of such groups include, but are
not limited to, alkyl
groups derived from linear alpha-olefins, isomerized alpha-olefins polymerized
alpha-olefins,
low molecular weight oligomers of propylene, and low molecular weight
oligomers of
isobutylene. Specific examples include but are not limited to butyl, pentyl,
hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, dipropyl, tripropyl,
tetrapropyl, pentapropyl,
hexapropyl, heptapropyl, octapropyl, diisobutyl, triisobutyl, tetraisobutyl,
pentaisobutyl,
hexaisobutyl, and heptaisobutyl.
[0015) The combined total of mono- and di-alkylated diphenylamine present in
the
compositions of the invention ranges from about 10 to about 80 weight percent
of the total
concentration of hindered phenolic, boronated hindered phenolic, and alkylated
diphenylamine.
The ratio of mono- to di-alkylated diphenylamine may vary from about 0~01:1,
to about 1:0.01.
[0019] Examples of suitable alkylated diphenylamines are nonylated
diphenylamines
(NDPA), octylated diphenylamines, mixed octylated/styrenated diphenylamines
(such as
Durad AX55), and mixed butylated/octylated diphenylamines (such as Vanlube
961).
Further, the nitrogen content of the alkylated diphenylamines can be in the
range of about 2.0 to
about 6.0 wt. %. Lower levels of nitrogen dilute the effectiveness of the
alkylated
diphenylamines while higher levels of nitrogen may adversely impact
compatibility of the
alkylated diphenylamines in the lubricant or the lubricant's volatilitye The
alkylated
diphenylamines can be a tiquid or low melting solid.
[00201 Organomolybdenum compounds suitable for use in the present invention
include
sulfur-free compounds, phosphorus-free compounds, and sulfur-containing
compounds. The
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molybdenum content of organornolybdenum compounds may vary from about 1 wt /Q
to about
15 wt / . The concentration of the organomolybdenum compound may range from
about 1 wt%
to about 40 wt% of the total concentration of hindered phenolic, boronated
hindered phenolic,
alkylated diphenylamine and organomolybdenum compound.
[0021] The amount of organomolybdenum compound used in compositions of the
present
invention is such that the weight ratio of molybdenum to boron ranges from
about 0.01:1 to
about 10:1. The molybdenum content of a lubricant oil can range from between
about 50 to
about 1000 ppm and the boron eontent can range between about 50 to about 500
ppm. The
molybdenum content of a lubricant oil can range from between about 100 to
about 400 ppm and
the boron content can range between about 100 to about 400 ppm.
[0022] Sulfur- and phosphorus-free organomolybdenum compounds may be prepared
by
reacting a sulfur and phosphorus-free molybdenum source with an organic
compound containing
amino and/or alcohol groups. Examples of sulfur- and phosphorus-free
molybdenum sources
include molybdenum trioxide, ammonium molybdate, sodium molybdate and
potassium
molybdate. The amino groups may be monoamines, diamines, or polyamines. The
alcohol
groups may be mono-substituted alcohols, diols or bis-alcohols, or
polyalcohols. As an
example, the reaction of diamines with fatty oils produces a product
containing both amino and
alcohol groups that can react with the sulfur- and phosphorus-free molybdenum
source.
[0023] Examples of sulfur- and phosphorus-free organomolybdenum compounds
suitable
for use in the present invention include the following: compounds prepared by
reacting certain
basic nitrogen compounds with a molybdenum source as defined in U.S. Patent
Nos. 4,259,195
and 4,261,843; compounds prepared by reacting a hydrocarbyl substituted
hydroxy alkylated
amine with a molybdenum source as defined in U.S. Patent No. 4,164,473;
compounds prepared
by reacting a phenol aldehyde condensation product, a mono-alkylated alkylene
diamine, and a
molybdenum source as defined in U.S. Patent No. 4,266,945; compounds prepared
by reacting a
fatty oil, diethanolamine, and a molybdenum source as defined in U.S. Patent
No. 4,889,647;
compounds prepared by reacting a fatty oil or acid with 2-(2-
aminoethyl)aminoethanol, and a
molybdenum source as defined in U.S. Patent No. 5,137,647; compounds prepared
by reacting a
secondary amine with a molybdenum source as defined in U.S. Patent No.
4,692,256;
compounds prepared by reacting a diol, diamino, or amino-alcohol compound with
a
molybdenum source as defined in U.S. I'atentNo. 5,412,130; compounds prepared
by reacting a
fatty oil, mono-alkylated alkylene diamine, and a molybdenum source as defined
in European
Patent Application EP 1 136 496 Al; and compounds prepared by reacting a fatty
acid, mono-
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allcylated alkylene diamine, glycerides, and a molybdenum source as defined in
European Patent
Application EP 1 136 497 Al.
[0024] Examples of commercial sulfur- and phosphorus-free oil soluble
molybdenum
compounds are Sakura-Lube 700 from Asahi Denka, and Molyvan 856B and Molyvan
855 from
R. T. Vanderbilt Company, Inc.
[0025] Molybdenum compounds prepared by reacting a fatty oil, diethanolamine,
and a
molybdenum source as defined in U. S. Patent 4,889,647 are sometimes
illustrated as having one
or both of the following structures,
O O
0 i H2 ~M R 11 N~CH2CI120~M
RCOCH2 CH'O/ \ CH2CH2O 0
wherein R is a fatty alkyl chain. The exact chemical structure of these
materials is not fully
known and may in fact be multi-component mixtures of many organomolybdenum
compoundse
[0026] Sulfur-containing organomolybdenum compounds may be prepared by a
variety of
methods. One method involves reacting a sulfur and phosphorus-free molybdenum
source with
an amino group and one or more sulfur sources. Sulfur sources include carbon
disulfide,
hydrogen sulfide, sodium sulfide and elemental sulfur. Alternatively, the
sulfur-containing
molybdenum compound may be prepared by reacting a sulfur containing molybdenum
source
with an amino group or thiuram group and optionally a second sulfur source.
Exarnples of
sulfur- and phosphorus-free molybdenum sources include molybdenum trioxide,
ammonium
molybdate, sodium molybdate, potassium molybdate and molybdenum halides. The
amino
groups may be monoamines, diamines, or polyamines. As an example, the reaction
of
molybdenum trioxide with a secondary amine and carbon disulfide produces
molybdenum
dithiocarbamates. Alternatively, the reaction of (NH4)2Mo3S13=n(H20) where n
varies between
0 to 2 with a tetralkylthiuram disulfide produces a trinuclear sulfur-
containing molybdenuin
dithiocarbamate.
[0027] Examples of sulfur-containing organomolybdenum compounds suitable for
use in the
present invention include the following: compounds prepared by reacting
molybdenum trioxide
with a secondary amine and carbon disulfide as defined in U.S. Patent Nos.
3,509,051 and
3,356,702; compounds prepared by reacting a sulfur-free molybdenuzn source
with a secondary
amine, carbon disulfide, and an additional sulfur source as defined in U.S.
Patent No. 4,098,705;
compounds prepared by reacting a molybdenum halide with a secondary amine and
carbon
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disulfide as defined in U. S. Patent No. 4,178,258; compounds prepared by
reacting a
molybdenum source with a basic nitrogen compound and a sulfur source as
defined in U.S.
Patent Nos. 4,263,152, 4,265,773, 4,272,387, 4,285,822, 4,369,119, and
4,395,343; compounds
prepared by reacting ammonium tetrathiomolybdate with a basic nitrogen
compound as defined
in U.S. Patent No. 4,283,295; compounds prepared by reacting an olefin,
sulfur, an amine and a
molybdenum source as defined in U.S. Patent No. 4,362,633; compounds prepared
by reacting
ammonium tetrathiomolybdate with a basic nitrogen compound and an organic
sulfur source as
defined in U.S. Patent No. 4,402,840; compounds prepared by reacting a
phenolic compound, an
amine and a molybdenum source with a sulfur source as defined in U. S. Patent
No. 4,466,901;
compounds prepared by reacting a triglyceride, a basic nitrogen compound, a
molybdenum
source, and a sulfur source as defined in U.S. Patent No. 4,765,918; compounds
prepared by
reacting alkali metal alkylthioxanthate salts with molybdenum halides as
defined in U.S. Patent
No, 4,966,719; compounds prepared by reacting a tetralkylthiuram disulfide
with molybdenum
hexacarbonyl as defined in U. S. Patent No. 4,978,464; compounds prepared by
reacting an alkyl
dixanthogen with molybdenum hexacarbonyl as defined in U.S. Patent No.
4,990,271;
compounds prepared by reacting alkali metal alkylxanthate salts with
dimolybdenum tetra-
acetate as defined in U.S. No. Patent 4,995,996; compounds prepared by
reacting
(NH4)2Mo3S13=2(H20) with an alkali metal dialkyldithiocarbamate or tetralkyl
thiuram disulfide
as define in U.S. Paten.t No. 6,232,276; compounds prepared by reacting an
ester or acid with a
diamine, a molybdenum source and carbon disulfide as defined in U.S. Patent
No. 6,103,674;
and compounds prepared by reacting an alkali metal dialkyldithiocarbamate with
3-
chloropropionic acid, followed by molybdenum trioxide, as defined in U.S.
Patent No.
6,117,826.
[0028] Exainples of commercial sulfur-containing oil soluble molybdenum
compounds are
Sakura-Lube 100, Sakura-Lube RO 155, Sakura-Lube 165, and Sakura-Lube(t 180
from Asahi
Denka Kogyo K.K., Molyvan0 A, Molyvan 807 and Molyvan 822 from R. T.
Vanderbilt
Company, and Naugalube Mo1yFM from Crompton Corporation.
[0029] Molybdenum dithiocarbamates are suitable organomolybdenum compounds and
have
the following structure:
S X X X S
RN-~ S-M \ \IVIo-S-C-N\R
R X R
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wherein R is independently selected from hydrogen or an alkyl group containing
4 to 18
carbons, and X is independently selected from oxygen or sulfur.
[0030] The lubricating oil may be any basestock or base oil (characterized as
Group I, Group
11, Group III, Group IV or Group V as defined by the API basestock
classification system), or
lubricant composed predominately of aromatics, naphthenics, paraffinics, poly-
alpha-olefins
and/or synthetic esters. Further, the lubricant may also contain additional
additives so as to
make the system acceptable for use in a variety of applications. These
additives include
dispersants, detergents, viscosity index improvers, pour point depressants,
anti-wear additives,
extreme pressure additives, friction modifiers, corrosion inhibitors, rust
inhibitors, emulsifiers,
demulsifiers, anti-foaming agents, colorants, seal swelling agents, and
additional antioxidants.
[0031] The present invention may be useful in passenger car engine oils, heavy
duty diesel
oils, medium speed diesel oils, railroad oils, marine engine oils, natural gas
engine oils, 2-cycle
engine oils, steam turbine oils, gas turbine oils, combined cycle turbine
oils, R&O oils, industrial
gear oils, automotive gear oils, compressor oils, manual transmission fluids,
automatic
transmission fluids, slideway oils, quench oils, flush oils and hydraulic
fluids. Suitable
applications are in engine oils. A suitable application is in low phosphorus
engine oils
characterized by a phosphorus content of less than 1000 ppm.
[0032] The lubricating oil additive concentrate may or may not contain a
diluent oil. If a
diluent oil is used, the diluent oil is typically present between 1 and 80 wt.
% of the concentrate.
[0033] Typically, the total amount of hindered phenolic, boronated hindered
phenolic,
alkylated diphenylamine, and organomolybdenum compound that are added to fully
formulated
oils depends upon the end use application. For example, in a turbine oil the
total amount of
hindered phenolic, boronated hindered phenolic, alkylated diphenylamine, and
organomolybdenum compound added to the oil ranges between about 0.05 and about
1.0 wt. %.
In contrast, in an engine oil the total amount of hindered phenolic, boronated
hindered phenolic,
alkylated diphenylamine and organomolybdeum compound added to the oil ranges
between
about 0.2 and about 3.0 wt.%. In ultra-low phosphorus engine oils the total
amount of hindered
phenolic, boronated hindered phenolic, and alkylated diphenylamine may
approach 5.0 wt. % or
more.
[0034] An example of a lubricating oil additive concentrate in accordance with
the present
invention is as follows: (a) 4,4-methylenebis(2,6-di-tert-butylphenol) @ 10
wt. %;
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(b) 4,4'-met@lenebis(2,6-di-tert-butylphenol) mono-(di-sec-butyl orthoborate)
and 4,4'-
rnethylenebis(2,6-di-tert-butylphenol) di-(di-sec-butyl orthoborate) 40 wt. %;
(c) dinonyldiphenylamine and monononyldiphenylamine @ 10 wt. %;
(d) a molybdenum dithiocarbamate containing 4.5 wt.% molybdenum @ 20 wt.%; and
(e) paraffinic diluent oil @ 20 wt. %.
[0035] An example of a low phosphorus engine oil in accordance with the
present invention
is as follows:
(a) 4,4-methylenebis(2,6-di-tert-butylphenol) @ 0.5 wt. %;
(b) 4,4'-methylenebis(2,6-di-tert-butylphenol) mono-(di-sec-butyl orthoborate)
and 4,4'-
methylenebis(2,6-di-tert-butylphenol) di-(di-sec-butyl orthoborate) @ 1.0 wt.
%;
(c) dinonyldiphenylamine and monononyldiphenylamine @ 0.75 wt. %;
(d) a molybdenum dithiocarbamate containing 4.5 wt.% molybdenum @ 0.2 wt.%
(e) a dispersant concentrate @ 4.8 wt. %;
(f) an overbased calcium detergent concentrate @ 1.8 wt. %;
(g) a neutral calcium detergent concentrate @ 0.5 wt. %;
(h) zinc dialkyldithiophosphate @ 0.6 weight %;
(i) a pour point depressant at 0.1 wt. %;
(j) a viscosity index improver concentrate @ 8.0 wt. %;
(k) an organic friction modifier @ 0.5 wt. %; and
(1) paraffinic lubricating oil @ 81.25 wt. %
Example A: Oil thickening and Oxidation at Elevated Temperatures
[0036] A passenger car engine oil preblend was prepared in accordance with the
present
invention by blending the following materials:
(a) 5.000 wt. % of an ashless dispersant;
(b) 1.875 wt. % of an overbased detergent containing calcium;
(c) 0.521 wt. % of a neutral detergent containing calcium;
(d) 0.625 wt. % of a secondary zinc dialkyldithiophosphate; and
(e) 91.979 wt. % of a 150N Group lI baseoil.
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To this engine oil preblend was added the components indicated in Table 1.
Table 1. Components of Examples A.l-A.6.
Engine Example Preblend HPE NDPA BMBDTBP MoDTC G2B0 Total
Oil Ex. Type (wt%) (wt%) (wt%) (wt%) (wt%, ppm Mo) (wt%) (wt%)
No.
A.1 Comparative 96.00 1.00 0.75 0.4,225 1.85 100.00
A.2 Comparative 96.00 1.25 0.75 0.4, 225 1.60 100,00
A.3 Invention 96.00 0.50 1.00 0.4, 225 2.10 100.00
A.4 Invention 96.00 0.75 1.00 0.4, 225 1.85 100.00
A.5 Invention 96.00 0.75 0.75 0.4, 225 2.10 100.00
A.6 Invention 96.00 0.75 1.25 0.4, 225 1.60 100.00
MoDTC = Molybdenum dithiocarbamate containing 4.5 wt.% molybdenum
BMBDTBP = a sample composed of: 15.6 wt.% 4,4-methylenebis(2,6-di-tert-
butylphenol, 38.6
wt.% 4,4'-methylenebis(2,6-di-tert-butylphenol)-mono-(di-sec-butyi
orthoborate), 17.4 wt.% 4,4'-
methylenebis(2,6-di-tert-butylphenol)-di-(di-sec-butyl orthoborate) (values
calculated based upon
HPLC analysis), 1.0 wt.% of an ashless dispersant, and 29.0 wt.% of a 500N
naphthenic diluent
oil. The sample has a boron content of 1.23 wt% as determined by ICP.
HPE = 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid, C7-C9branched alkyl
esters
NDPA = Nonylated diphenylamine
G2BO = 150N Group II baseoil
[0037] The oxidative stability of these finished engine oils was evaluated in
a bulk oil
oxidation test. Each oil (300 mL) was treated with an iron naphthenate
oxidation catalyst to
deliver 110 ppm of iron to the finished oil. The oils were heated in a block
heater at 150 C,
while 10 liters/hour of dry oxygen was bubbled through the oil. Samples of the
oxidized oils
were removed at 24, 48, 72, 96, 120, 144, 168 and 192 hours. Kinematic
viscosities of each
sample were determined at 40 C. The percent viscosity increase of the oxidized
oil versus the
fresh oil was calculated. The percent viscosity increase results are shown in
Table 2.
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Table 2. Percent viscosity increase of finished oils A.1-A.6 in bulk oil
oxidation test.
Sample 0 24 48 72 96 120 144 168 192
1
0 2.5 3.5 5.1 33.5 172.4 596.8
(comparative)
2
0 2.9 7.9 100.0 382.1
(comparative)
.3 (invention) 0 0.3 1.3 2.4 3.4 15.4 148.3 716.6
4 (invention) 0 0.8 1.9 2.8 3.3 i.3 .9 50.6 283.0
A.5 (inventio0 0.2 1.2 2.1 2.4 3.5 1.7 13.9 153.8
.6 (invention) 0 0.9 2.4 3.4 .4 5,3 8.0 19.4 290.7
[0038] A higher percent viscosity increase is a measure of increased oxidation
and
degradation of the lubricant. These results clearly show that the inventive
antioxidant
combination in Examples A.3 to A.6 provide superior oxidation protection
compared to the
other Examples (A.1-A.2). Antioxidant systems that do not contain the
combination of 4,4'-
methylenebis(2,6-di-tert-butylphenol), boronated 4,4'-m ethyl enebis(2,6-di-
tert-butylphenol),
nonylated diphenylamine and organomolybdenum compound show poor oxidation
control while
systems containing BMBDTBP, NDPA and MoDTC show superior oxidative control.
These
results are shown graphically in Figure 1.
Example B - Pressurized Differential Scanning Calorimetry (PDSC)
[0039] The oxidative stability of the finished engine oils prepared in Example
A was
evaluated using pressurized differential scanning calorimetry following the
ASTM standard test
method D 6186 and using the following operation conditions: isothermal
temperature = 180 C,
oxygen gas @ 500 psig with a flow rate of 100 mL/min, approximately 3 mg
sample size, open
aluminum pans. Each oil was treated with an iron naphthenate oxidation
catalyst to deliver
55 ppm of iron to the finished oil. Oxidation induction times (OIT) were
determined according
to the ASTM method. Each oil was tested in duplicate and the results averaged.
The OIT
results are shown in Table 3.
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Table 3. Oxidation Induction Times in minutes for finished oils A.1-A.6 tested
using PDSC.
Sample ID OIT OIT AVG.
A.1 109.48 119.12 114.30
A.2 112.33 109.2 110.77
A.3 111.09 113.15 112.12
A.4 156.44 147.78 152.11
A.5 143.68 148.24 145.96
A.6 146.67 147.36 147.02
[0040] A longer induction time is a measure of increased oxidation stability
of the lubricant.
These results clearly show that the inventive antioxidant combination in
Examples A.4 to A.6
provide superior oxidation protection compared to the non-inventive Examples
(A.1-A.2).
Antioxidant systems that do not contain the combination of 4,4'-
methylenebis(2,6-di-tert-
butylphenol), boronated 4,4'-methylenebis(2,6-di-tert-butylphenol), nonylated
diphenylamine
and molybdenum show poor oxidation control while systems containing BMDTBP,
NDPA and
MoDTC show superior oxidative control. Also, considerably less, i.e. 25 %
less, antioxidant is
used in inventive oil A.3 versus non-inventive oil A.2 in order to deliver the
same performance
level in the PDSC (112.12 minutes and 110.77 minutes statistically
equivalent).
[0041] While the compositions and methods of this invention have been
described in terms
of preferred embodiments, it will be apparent to those of skill in the art
that variations may be
applied to the compositions, methods and/or processes and in the steps or in
the sequence of
steps of the methods described herein without departing from the concept and
scope of the
invention. More specifically, it will be apparent that certain agents which
are both chemically
and physiologically related may be substituted for the agents described herein
while the same or
similar results would be achieved. All such similar substitutes and
modifications apparent to
those skilled in the art are deemed to be within the scope and concept of the
invention.
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