U.S. patent number RE40,595 [Application Number 11/133,442] was granted by the patent office on 2008-12-02 for lubricant containing molybdenum compound and secondary diarylamine.
This patent grant is currently assigned to Afton Chemical Intangibles LLC. Invention is credited to Mark Thomas Devlin, Vincent James Gatto.
United States Patent |
RE40,595 |
Gatto , et al. |
December 2, 2008 |
Lubricant containing molybdenum compound and secondary
diarylamine
Abstract
There is disclosed a lubricating oil composition which contains
from about 100 to 450 parts per million of molybdenum from a
molybdenum compound which is substantially free of active sulfur
and about 750 to 5,000 parts per million of a secondary
diarylamine. This combination of ingredients provides improved
oxidation control and friction modifier performance to the
lubricating oil. The composition is particularly suited for use as
a crankcase lubricant.
Inventors: |
Gatto; Vincent James (Baton
Rouge, LA), Devlin; Mark Thomas (Richmond, VA) |
Assignee: |
Afton Chemical Intangibles LLC
(Richmond, VA)
|
Family
ID: |
27000622 |
Appl.
No.: |
11/133,442 |
Filed: |
May 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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09604285 |
Jun 26, 2000 |
Re. 38929 |
|
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09359770 |
Jul 22, 1999 |
Re. 37363 |
|
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Reissue of: |
08559879 |
Nov 20, 1995 |
05650381 |
Jul 22, 1997 |
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Current U.S.
Class: |
508/362; 508/383;
508/371; 508/391; 508/460; 508/563; 508/584; 508/527; 508/459;
508/390; 508/385; 508/364 |
Current CPC
Class: |
C10M
141/06 (20130101); C10M 167/00 (20130101); C10M
141/12 (20130101); C10M 163/00 (20130101); C10M
2207/289 (20130101); C10M 2219/088 (20130101); C10M
2205/024 (20130101); C10M 2227/08 (20130101); C10N
2040/253 (20200501); C10N 2070/02 (20200501); C10M
2205/06 (20130101); C10M 2219/108 (20130101); C10N
2040/28 (20130101); C10M 2215/30 (20130101); C10M
2207/026 (20130101); C10M 2217/046 (20130101); C10M
2207/129 (20130101); C10N 2010/00 (20130101); C10M
2207/09 (20130101); C10M 2219/022 (20130101); C10M
2219/089 (20130101); C10M 2223/065 (20130101); C10M
2207/028 (20130101); C10M 2215/221 (20130101); C10M
2217/06 (20130101); C10M 2207/142 (20130101); C10N
2040/25 (20130101); C10N 2040/252 (20200501); C10M
2207/16 (20130101); C10M 2207/26 (20130101); C10M
2207/262 (20130101); C10M 2215/06 (20130101); C10M
2227/082 (20130101); C10N 2010/04 (20130101); C10M
2215/226 (20130101); C10M 2215/26 (20130101); C10M
2223/045 (20130101); C10M 2227/081 (20130101); C10M
2209/084 (20130101); C10M 2215/24 (20130101); C10M
2215/066 (20130101); C10M 2207/125 (20130101); C10M
2215/22 (20130101); C10M 2207/122 (20130101); C10M
2215/04 (20130101); C10N 2040/251 (20200501); C10M
2227/083 (20130101); C10N 2040/255 (20200501); C10M
2205/00 (20130101); C10M 2207/121 (20130101); C10M
2209/086 (20130101); C10M 2227/09 (20130101); C10M
2219/087 (20130101); C10M 2215/065 (20130101); C10M
2219/068 (20130101); C10N 2040/08 (20130101); C10M
2207/14 (20130101); C10M 2215/067 (20130101); C10M
2219/082 (20130101); C10N 2010/12 (20130101); C10M
2207/126 (20130101); C10M 2215/064 (20130101); C10M
2215/068 (20130101); C10M 2219/046 (20130101); C10M
2219/066 (20130101); C10M 2205/026 (20130101); C10M
2215/225 (20130101); C10M 2207/024 (20130101) |
Current International
Class: |
C10M
141/12 (20060101) |
Field of
Search: |
;508/364,362 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 696 636 |
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Feb 1996 |
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EP |
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2 097 422 |
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Nov 1982 |
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GB |
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A-06-1000880 |
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Apr 1994 |
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JP |
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A-07-286190 |
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Oct 1995 |
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JP |
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WO 95/02027 |
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Jan 1995 |
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WO |
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WO 95/07962 |
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Mar 1995 |
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WO |
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WO 95/07963 |
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Mar 1995 |
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WO |
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WO 95/07966 |
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Mar 1995 |
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WO |
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WO 95/27022 |
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Oct 1995 |
|
WO |
|
Other References
Vandebilt Lubricant Additives Technical Bulletin 941, R.T.
Vanderbilt Company, Inc (Jun. 1994). cited by examiner .
MOLYVAN (R) 822 Oil Soluble Molybdenum-Sulfur Lubricant Additive
Non -Phosphorus Friction Reducer Antioxidant, Technical Data,
MV-822-1A/8604 (8203), R.T. Vanderbilt Company, Inc. (Apr. 1986).
cited by examiner.
|
Primary Examiner: McAvoy; Ellen M.
Attorney, Agent or Firm: Fitch, Even, Tabin, Flannery
Rainear; Dennis
Parent Case Text
.Iadd.This is application Ser. No. 11/133,442, filed May 20, 2005,
is a continuation of U.S. application Ser. No. 09/604,285, filed
Jun. 26, 2000, now Re 38,929E, which is a continuation of U.S.
application Ser. No. 09/359,770, filed Jul. 22, 1999, now Re
37,363E, both of which are reissues of U.S. Pat. No. 5,650,381,
which issued from U.S. patent application Ser. No. 08/559,879,
filed Nov. 20, 1995, the complete disclosures of which are
incorporated herein by reference..Iaddend.
Claims
What is claimed is:
.[.1. A lubricating composition comprising a major amount of
lubricating oil, an oil soluble molybdenum compound providing about
100 to 450 parts per million of molybdenum, said molybdenum
compound selected from the group consisting of a sulfur and
phosphorus free organic amide molybdenum complex and a molybdenum
carboxylate wherein the carboxylate anion has from about 4 to 30
carbon atoms and about 750 to 5,000 parts per million of an oil
soluble secondary diarylamine..].
.[.2. The composition of claim 1 wherein the carboxylate is that of
a monocarboxylic aliphatic acid having from about 4 to 18 carbon
atoms or an alicyclic acid having from about 4 to 12 carbon
atoms..].
.[.3. The composition of claim 1 wherein the diarylamine has from
about 6 to 30 carbon atoms in each of the aryl groups..].
.[.4. The composition of claim 3 wherein at least one of the aryl
groups is alkaryl having from 7 to 20 carbon atoms in the alkyl
group..].
.[.5. The composition of claim 1 wherein the secondary diarylamine
is of the formula: ##STR00002## wherein R.sup.1 and R.sup.2 each
independently represent an aryl group having from about 6 to 30
carbon atoms..].
.[.6. The composition of claim 1 wherein: the molybdenum
carboxylate is that of an aliphatic acid having from about 4 to 18
carbon atoms or an alicyclic acid having from 4 to 12 carbon atoms;
each of the aryl groups of the amine is a member selected from the
group consisting of phenyl, naphthyl, alkphenyl wherein the alkyl
portion has from about 4 to 18 carbon atoms and alknaphthyl wherein
the alkyl portion has about 4 to 18 carbon atoms; the quantity of
molybdenum is from about 100 to 250 parts per million; and the
quantity of amine is from about 1,000 to 4,000 parts per
million..].
.[.7. A method for improving the antioxidancy and friction
properties of a lubricant which comprises including in the
lubricant, a molybdenum compound which provides about 100 to 450
parts per million of molybdenum said molybdenum compound selected
from the group consisting of a sulfur and phosphorus free organic
amide molybdenum complex and a molybdenum carboxylate wherein the
carboxylate anion has from about 4 to 30 carbon atoms and about 750
to 5,000 parts per million of an oil soluble secondary
diarylamine..].
.[.8. The method of claim 7 wherein the amine is of the formula
##STR00003## wherein each of R.sup.1 and R.sup.2 is alkphenyl
having from about 4 to 18 carbon atoms in each alkyl group..].
.[.9. The method of claim 8 wherein the molybdenum carboxylate is
prepared from an acid having from 4 to 18 carbon atoms and the
quantity of molybdenum from the molybdenum carboxylate is from
about 100 to 250 parts per million and the quantity of the amine is
from about 1,200 to 3,000 parts per million..].
.[.10. The method of claim 9 wherein the acid is a monocarboxylic
saturated fatty acid..].
.[.11. The method of claim 8 wherein the molybdenum carboxylate is
molybdenum 2-ethylhexanoate..].
.[.12. The method of claim 7 wherein the molybdenun compound is a
sulfur and phosphorus free organic amide molybdenum complex..].
.[.13. A lubricating oil concentrate prepared by dissolving a total
of from about 2.5 to 90 parts by weight of an oil soluble
molybdenum compound selected from the group consisting of a sulfur
and phosphorus free organic amide molybdenum complex and a
molybdenum carboxylate derived from an organic carboxylic acid
having about 4 to 30 carbon atoms and an oil soluble secondary
diarylamine dissolved in 10 to 97.5 parts of a solvent wherein the
weight ratio of molybdenum to amine is from about 0.02 to 0.6 parts
of molybdenum for each part of amine..].
.[.14. The concentrate of claim 13 wherein the solvent is a mineral
oil or synthetic oil and the ratio of molybdenum to amine is from
about 0.04 to 0.4 parts of the molybdenum for each part of the
amine, the molybdenum carboxylate is that of a monocarboxylic
aliphatic acid having from about 4 to 18 carbon atoms or an
aliphatic acid having from about 4 to 12 carbon atoms, and at least
one of the aryl groups of the amine is alkaryl having from 7 to 20
carbon atoms in the alkyl group..].
.[.15. The concentrate of claim 13 wherein one or more of the
following additives are further present: a dispersant; a detergent;
and a zinc dihydrocarbyl dithiophosphate..].
.[.16. A lubricating oil composition prepared by mixing an oil
soluble molybdenum compound selected from the group consisting of a
sulfur and phosphorus free organic amide molybdenum complex and a
molybdenum carboxylate derived from monocarboxylic acids selected
from the group consisting of aliphatic acids having about 4 to 18
carbon atoms, alicyclic acids containing from 4 to 12 carbon atoms
and aromatic acids containing from 7 to 14 carbon atoms and an oil
soluble secondary diaryl amine in a lubricating oil wherein the
concentration of the molybdenum in the oil is from about 100 to 450
parts per million and the concentration of the amine in the oil is
from about 750 to 5,000 parts per million based on said
composition..].
.[.17. The lubrication composition of claim 16 wherein: A. the
molybdenum compound is a molybdenum carboxylate of an aliphatic
acid having from 4 to 18 carbon atoms and the concentration thereof
is from about 100 to 250 parts per million of the composition; and
B. the diaryl amine is of the formula: ##STR00004## wherein R.sup.1
and R.sup.2 each independently represent an aryl group having from
about 6 to 30 carbon atoms and the concentration thereof is from
about 1,000 to 4,000 parts per million of the composition..].
.[.18. The lubrication composition of claim 17 wherein the
molybdenum carboxylate is that of a fatty acid having from about 4
to 18 carbon atoms and each of R.sup.1 and R.sup.2 of the amine is
a member selected from the group consisting of phenyl, naphthyl,
alkphenyl having from about 4 to 18 carbon atoms in the alkyl group
and alknaphthyl having from about 4 to 18 carbon atoms in the alkyl
group..].
.[.19. A method for improving the antioxidant and friction
properties of a lubricant which comprises adding to the lubricant
an oil soluble molybdenum carboxylate derived from an organic
carboxylic acid having from about 4 to 30 carbon atoms and wherein
said molybdenum carboxylate provides about 100 to 450 parts per
million of molybdenum and about 750 to 5,000 parts per million of
an oil soluble secondary diarylamine..].
.[.20. The method of claim 19 wherein the carboxylate is derived
from a carboxylic acid selected from the group consisting of:
butyric acid; valeric acid; caproic acid heptanoic acid;
cyclohexanecarboxylic acid; cyclodecanoic acid; naphthenic acid;
phenyl acetic acid; 2-methylhexanoic acid; 2-ethylhexanoic acid;
suberic acid; octanoic acid; nonanoic acid; decanoic acid;
undecanoic acid; lauric acid, tridecanoic acid; myristic acid;
pentadecanoic acid; palmitic acid; linolenic acid; heptadecanoic
acid; stearic acid; oleic acid; nonadecanoic acid; eicosanoic acid;
heneicosanoic acid; docosanoic acid; and erucic acid..].
.[.21. The method of claim 20 wherein: the molybdenum carboxylate
provides about 100 to 250 parts per million of molybdenum; about
1,000 to 4,000 parts per million of the oil soluble secondary
diarylamine are added to the lubricant and said amine is of the
formula ##STR00005## wherein each of R.sup.1 and R.sup.2 is
alkphenyl having from about 4 to 18 carbon atoms in each alkyl
group..].
.Iadd.22. A lubricating composition comprising: a major amount of
lubricating oil, at least one oil soluble molybdenum compound that
is at least substantially free of phosphorus and at least
substantially free of sulfur that becomes more acidic in the
lubricating oil upon use, and at least one oil soluble secondary
diarylamine, wherein the ratio of said oil soluble molybdenum
compound relative to said oil soluble secondary diarylamine is
about 0.02 to 0.6 parts by weight molybdenum per part of said
secondary diarylamine, said oil soluble secondary diarylamine is
present in an amount of at least about 750 to about 5,000 parts per
million of said lubricating composition..Iaddend.
.Iadd.23. A lubricating composition comprising: a major amount of
lubricating oil, at least one oil soluble molybdenum compound that
is at least substantially free of phosphorus and at least
substantially free of sulfur that becomes more acidic in the
lubricating oil upon use, and at least one oil soluble secondary
diarylamine, wherein the ratio of said oil soluble molybdenum
compound relative to said secondary diarylamine is about 0.02 to
0.6 parts by weight molybdenum per part of said secondary
diarylamine compound and said oil soluble molybdenum compound is
present in an amount of about 100 to 468 parts per million of
molybdenum relative to said lubricating composition..Iaddend.
.Iadd.24. A method for lubricating an automotive or truck crankcase
or transmission comprising adding a lubricating composition
according to claim 22 or 23 to said crankcase or
transmission..Iaddend.
.Iadd.25. A lubricated automotive or truck crankcase or
transmission obtained according to claim 23..Iaddend.
.Iadd.26. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is
sulfur-free..Iaddend.
.Iadd.27. A lubricating composition according to claim 22, wherein
the amount of said secondary diarylamine is about 750 to 5,000
parts per million of said lubricating composition..Iaddend.
.Iadd.28. A lubricating composition according to claim 22 or 23,
wherein the amount of said oil soluble secondary diarylamine is
from 1,000 to 4,000 parts per million..Iaddend.
.Iadd.29. A lubricating composition according to claim 22 or 23,
wherein the amount of said oil soluble secondary diarylamine is
from 1,200 to 3,000 parts per million..Iaddend.
.Iadd.30. A lubricating composition according to claim 22 or 23,
wherein molybdenum is present from about 0.040 to 0.4 parts by
weight molybdenum relative to said oil soluble secondary
diarylamine..Iaddend.
.Iadd.31. A lubricating composition according to claim 22 or 23,
wherein molybdenum is present from about 0.05 to 0.3 parts by
weight molybdenum relative to said oil soluble secondary
diarylamine..Iaddend.
.Iadd.32. A lubricating composition according to claim 22 or 23,
wherein the molybdenum compound is at least one of molybdenum
naphthenate, molybdenum octoate or molybdenum
2-ethylhexanoate..Iaddend.
.Iadd.33. A lubricating composition according to claim 22 or 23,
wherein the quantity of molybdenum is from 100 to 250 parts per
million (by weight)..Iaddend.
.Iadd.34. A lubricating composition according to claim 22 or 23,
wherein the quantity of molybdenum is from 125 to 250 parts per
million (by weight)..Iaddend.
.Iadd.35. A lubricating composition according to claim 22 or 23,
wherein the molybdenum compound is a molybdenum
carboxylate..Iaddend.
.Iadd.36. A lubricating composition according to claim 35, wherein
the carboxylate has from 4 to 30 carbon atoms..Iaddend.
.Iadd.37. A lubricating composition according to claim 35, wherein
the molybdenum carboxylate is that of an aliphatic or
cycloaliphatic acid having from 4 to 18 carbon atoms..Iaddend.
.Iadd.38. A lubricating composition according to claim 35, wherein
the carboxylate is that of a monocarboxylic aliphatic or
cycloaliphatic acid having an alkyl group of from 6 to 18 carbon
atoms..Iaddend.
.Iadd.39. A lubricating composition according to claim 35, wherein
the carboxylate is that of a fatty acid..Iaddend.
.Iadd.40. A lubricating composition according to claim 39, wherein
the fatty acid has 6 to 14 carbon atoms..Iaddend.
.Iadd.41. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is obtained from a
molybdenum source and an active hydrogen compound, said molybdenum
source is selected from the group consisting of ammonium
molybdates, molybdenum trioxide, and molybdenum acetylacetonates,
and said active hydrogen compound is selected from the group
consisting of alcohols, polyols, primary amines, secondary amines,
polyamines, phenols, ketones, and anilines..Iaddend.
.Iadd.42. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is at least one glycol
molybdenum complex..Iaddend.
.Iadd.43. A lubricating composition according to claim 22 or 23,
wherein the oil soluble molybdenum compound is prepared by: (a)
introducing into a reaction zone a compound selected from
sulfonates, phenates and salicylates, wherein said compound is an
overbased alkaline earth or alkali metal compound; (b) adding to
said reaction zone a solvent to solubilize said compound and to
form a mixture A; (c) heating said mixture A to an elevated
temperature of 49.degree. C. or less; (d) preparing an aqueous
solution of a molybdenum compound at a temperature of 49.degree. C.
or less; (e) adding said aqueous solution of said molybdenum
compound to said mixture A with stirring during a period of about
15 minutes or less to form a mixture B; (f) adding said mixture B
to a non-polar compound as to temperature of 104.degree. C. or
greater within a period of up to 40 minutes wherein resulting
mixture C during said addition is at a temperature of at least
104.degree. C.; (g) driving off said water and said non-polar
compound as overhead by increasing the temperature of said mixture
C to 115.degree. C. to 149.degree. C. to obtain a water-free
composition; (h) adding additional quantity of a non-polar compound
to said water-free composition to dilute said composition to
clarify said composition by filtration or centrifugation; (i)
heating said clarified composition to a temperature of from
149.degree. C. to 204.degree. C. to remove solvent and said
non-polar compound and to recover product comprising an overbased
molybdenum-containing alkaline earth metal or alkali metal
composition..Iaddend.
.Iadd.44. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is at least one
organic amide molybdenum complex..Iaddend.
.Iadd.45. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is a molybdenum
complex obtained by reacting a fatty oil, diethanolamine and
molybdenum source..Iaddend.
.Iadd.46. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is obtained by
reacting a molybdenum source with a fatty acid and a
2-(2-aminoethyl)aminoethanol..Iaddend.
.Iadd.47. A lubricating composition according to claim 22 or 23,
wherein the secondary diarylamine has from 6 to 30 carbon atoms in
each of the aryl groups..Iaddend.
.Iadd.48. A lubricating composition according to claim 22 or 23,
wherein the secondary diarylamine is of the formula: ##STR00006##
wherein R.sup.1 and R.sup.2 each independently represent an aryl
group having from 6 to 30 carbon atoms..Iaddend.
.Iadd.49. A lubricating composition according to claim 48, wherein
at least one of said aryl groups has from 7 to 20 carbon
atoms..Iaddend.
.Iadd.50. A lubricating composition according to claim 48, wherein
each of the aryl groups of the amine is selected from phenyl,
naphthyl, alkylphenyl and alkylnapthyl wherein the alkyl portion
has from 4 to 18 carbon atoms..Iaddend.
.Iadd.51. A lubricating composition according to claim 48, wherein
both aryl groups are alkaryl having from 7 to 20 carbon
atoms..Iaddend.
.Iadd.52. A lubricating composition according to claim 48, wherein
each aryl group is alkylphenyl having from 6 to 18 carbon atoms in
each alkyl group..Iaddend.
.Iadd.53. A lubricating composition according to claim 22 or 23,
wherein said lubricating composition further comprises at least one
of the following additives: a dispersant; a detergent; and a zinc
dihydrocarbyl dithiophosphate..Iaddend.
.Iadd.54. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound is obtained by
reaction of an ammonium molybdate with a carboxylic acid in the
presence of an amine..Iaddend.
.Iadd.55. A lubricating composition according to claim 22 or 23,
wherein said oil soluble molybdenum compound contains an
amine..Iaddend.
.Iadd.56. A method for improving the antioxidancy and friction
properties of a lubricant which comprises including in the
lubricant a molybdenum compound which is at least substantially
free of phosphorus and is at least substantially free of sulfur
that becomes more acidic in the lubricant upon use, said molybdenum
compound providing about 100 to 468 parts per million of molybdenum
to the lubricant, and about 750 to 5000 parts per million of an oil
soluble secondary diarylamine..Iaddend.
.Iadd.57. A lubricating composition according to claim 22 or 23,
wherein said lubricating composition further comprises a zinc
dihydrocarbyl dithiophosphate..Iaddend.
.Iadd.58. A lubricating composition according to claim 57, wherein
said lubricating composition contains from 0.5 wt. % to 1.5 wt. %
of zinc dihydrocarbyl dithiophosphate..Iaddend.
.Iadd.59. A lubricating composition according to claim 22 or 23,
wherein said lubricating composition further comprises a
detergent..Iaddend.
.Iadd.60. A lubricating composition according to claim 59, wherein
said detergent comprises a neutral or overbased alkali or alkaline
earth metal sulfonate, a neutral or overbased alkali or alkaline
earth metal phenate, or an overbased alkaline earth metal
salicylate..Iaddend.
.Iadd.61. A lubricating composition according to claim 60, wherein
said lubricating composition contains about 1.0 wt. % to 2.5 wt. %
of detergent..Iaddend.
.Iadd.62. A lubricating composition according to claim 22 or 23,
wherein said lubricating composition further comprises a
supplemental friction modifier..Iaddend.
.Iadd.63. A lubricating composition according to claim 22 or 23,
wherein said lubricant composition further comprises zinc
dihydrocarbyl dithiophosphate; a detergent; and a supplemental
friction modifier..Iaddend.
.Iadd.64. A lubricating composition according to claim 63, wherein
said lubricating composition contains 0.5 wt. % to 1.5 wt. % of
zinc dihydrocarbyl dithiophosphate and about 1.0 wt. % to 2.5 wt. %
of detergent..Iaddend.
.Iadd.65. A lubricating composition according to claim 22, wherein
said lubricating composition further comprises a zinc dihydrocarbyl
dithiophosphate; a detergent comprising a neutral or overbased
alkali or alkaline earth metal sulfonate, a neutral or overbased
alkali or alkaline earth metal phenate, or an overbased alkaline
earth metal salicylate; and a supplemental friction
modifier..Iaddend.
.Iadd.66. A lubricating composition according to claim 23, wherein
said lubricating composition contains 104 ppm to 364 ppm molybdenum
and said lubricating composition further comprises a zinc
dihydrocarbyl dithiophosphate; a detergent that comprises a neutral
or overbased alkali or alkaline earth metal sulfonate, a neutral or
overbased alkali or alkaline earth metal phenate, or an overbased
alkaline earth metal salicylate; and a supplemental friction
modifier..Iaddend.
.Iadd.67. A lubricating composition according to claim 35, wherein
carboxylate is derived from a carboxylic acid selected from the
group consisting of: butyric acid; valeric acid; caproic acid
heptanoic acid; cyclohexanecarboxylic acid; cyclodecanoic acid;
naphthenic acid; phenyl acetic acid; 2-methylhexanoic acid;
2-ethylhexanoic acid; suberic acid; octanoic acid; nonanoic acid;
decanoic acid; undecanoic acid; lauric acid; tridecanoic acid;
myristic acid; pentadecanoic acid; palmitic acid; linolenic acid;
heptadecanoic acid; stearic acid; oleic acid; nonadecanoic acid;
eicosanoic acid; henicosanoic acid; docosanoic acid; and erucic
acid..Iaddend.
.Iadd.68. A method for lubricating an internal combustion engine
comprising adding a lubricating composition according to claim 22
or claim 23 to said engine..Iaddend.
.Iadd.69. A lubricated engine obtained by the method according to
claim 68..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to lubricating oil compositions, their
method of preparation, and use. More specifically this invention
relates to lubricating oil compositions which contain a molybdenum
compound and a secondary diarylamine wherein the molybdenum
compound is substantially free of active sulfur. The use of both
the molybdenum and amine within certain concentrations provide
improved oxidation control and friction modifier performance to
lubricating oil compositions. The lubricating oil compositions of
this invention are particularly useful as crankcase lubricants.
2. Description of the Related Art
Lubricating oils as used in the internal combustion engines of
automobiles or trucks are subjected to a demanding environment
during use. This environment results in the oil suffering oxidation
which is catalyzed by the presence of impurities in the oil such as
iron compounds and is also promoted by the elevated temperatures of
the oil during use. This oxidation of lubrication oils during use
is usually controlled to some extent by the use of antioxidant
additives which may extend the useful life of the oil, particularly
by reducing or preventing unacceptable viscosity increases.
We have now discovered that a combination of about 100 to 450 parts
per million (ppm) of molybdenum from an oil soluble molybdenum
compound which is substantially free of active sulfur and about 750
to 5,000 ppm of an oil soluble secondary diarylamine is highly
effective in inhibiting oxidation in lubricant compositions and
that this antioxidant performance is supplemented by improved
friction modifier performance. The molybdenum acts synergistically
with secondary diarylamines to provide significant improvement in
oxidation control. In addition to excellent oxidation control, the
molybdenum compounds also act as friction modifiers to provide
substantial fuel economy performance.
Lubricant compositions containing various molybdenum compounds and
aromatic amines have been used in lubricating oils. Such
compositions include active sulfur or phosphorus as part of the
molybdenum compound, use additional metallic additives, various
amine additives which are different from those used in this
invention, and/or have concentrations of molybdenum and amine which
do not show the synergistic results obtained by this invention.
U.S. Pat. No. 3,285,942 of Nov. 15, 1966 to Esso discloses the
preparation of glycol molybdate complexes which have utility in
lubrication oils.
U.S. Pat. No. 4,394,279 of Jul. 19, 1983 to L. de Vries et al.
discloses an antioxidant additive combination for lubrication oils
prepared by combining (a) an active sulfur containing molybdenum
compound prepared by reacting an acidic molybdenum compound, a
basic nitrogen compound and carbon disulfide with (b) an aromatic
amine compound.
U.S. Pat. No. 4,832,857 of May 23, 1989 to Amoco Corp discloses a
process for preparation of overbased molybdenum alkaline earth
metal and alkali metal dispersions for use in lubricating oil
compositions.
U.S. Pat. No. 4,846,983 of Jul. 11, 1989 to W. C. Ward discloses
molybdenum containing hydrocarbyl dithiocarbamates prepared from
primary amines that impart anti-wear, antioxidant, extreme
pressure, and friction properties to lubricating oils. Again, among
other shortcomings, these molybdenum compounds contain substantial
quantities of active sulfur.
U.S. Pat. No. 4,889,647 of Dec. 26, 1989 to R. T. Vanderbilt Co.
discloses organic molybdenum complexes for use in lubrication oil
compositions.
U.S. Pat. No. 5,137,647 of Aug. 11, 1992 to R. T. Vanderbilt Co.
discloses molybdenum complexes for use in fuels and lubricating oil
compositions.
U.S. Pat. No. 5,143,633 of Sept. 1, 1992 to Gallo et al discloses
superbasic additives for lubricant oils containing an organic
molybdenum complex.
WO95/07962 of Mar. 23, 1995 to A. Richie et al. discloses a
crankcase lubricant composition for use in automobile or truck
engines which contains copper, molybdenum, and aromatic amines. In
addition to the requirement for use of copper, this publication
recites a very broad range of concentrations for the molybdenum and
the amine whereas the concentrations of amine used with the
molybdenum in the examples of that publication is well outside the
range which this invention has found to be synergistic. Also, many
of the molybdenum compounds of this reference contain active
sulphur, phosphorus, and other elements and the amines include
compounds such as primary amines which were not found synergistic
with the molybdenum carboxylates of this invention.
WO95/07963 of 23 Mar. 1995 to H. Shaub discloses highly sulfurized
molybdenum compounds and various secondary aromatic amines having
at least one aromatic group for producing a synergistic antioxidant
effect when used as an antioxidant additive for lubricating oils.
Again the molybdenum compounds contain active sulfur.
WO95/07966 of 23 Mar. 1995 to J. Atherton et al. discloses engine
oil lubricants of various molybdenum compounds including that of
some with active sulfur, certain organo-phosphorus compounds, an
aminic antioxidant and a phenolic antioxidant within certain
proportions.
SUMMARY OF THE INVENTION
In one aspect, this invention is directed to a lubricating
composition comprising (a) a major amount of lubrication oil, (b)
an oil soluble molybdenum compound substantially free of active
sulfur which provides about 100 to 450 parts per million of
molybdenum, and (c) about 750 to 5,000 parts per million (ppm) of
an oil soluble secondary diarylamine.
In another aspect, the invention is directed to a method for
improving the antioxidancy and friction properties of a lubricant
by incorporating in the lubricant a molybdenum compound which is
substantially free of active sulfur and a secondary diarylamine in
the above described concentrations.
In still another aspect, the invention is directed to a lubrication
oil concentrate comprising a solvent and a combination of from
about 2.5 to 90 percent by weight of an oil soluble molybdenum
compound which is substantially free of active sulfur and an oil
soluble secondary diarylamine wherein the weight ratio of
molybdenum from the molybdenum compound to the diarylamine in the
concentrate is from about 0.020 to 0.60 parts of molybdenum for
each part of amine.
In yet another aspect, the invention is directed to a lubricating
composition prepared by mixing 100 to 450 parts per million of oil
soluble molybdenum compound substantially free of active sulfur and
750 to 5,000 parts of a secondary diaryl amine in a lubricating
composition.
In a yet further aspect, the invention is directed to a lubrication
oil concentrate prepared by dissolving in about 10 to 97.5 parts of
a solvent a total of 2.5 to 90 parts of an oil soluble molybdenum
compound substantially free of active sulfur and an oil soluble
secondary diaryl amine.
In yet a still further aspect, the molybdenum compound used in the
various compositions and methods of this invention is substantially
free of sulfur.
The compositions of this invention have various uses as lubricants
such as for automotive and truck crankcase lubricants as well as
transmission lubricants.
A key advantage of this invention is the multifunctional nature of
the molybdenum/diarylamine combination and the relatively low treat
levels required for a performance benefit. This additive
combination provides both oxidation control and friction control to
the oil. This reduces the need for supplemental oxidation
protection and frictional properties and should reduce the overall
cost of the entire additive package. Further cost reduction is
gained by the low treat levels employed.
DETAILED DESCRIPTION OF THE INVENTION
The molybdenum compound used in this invention can be any
molybdenum compound which is soluble in the lubricant or formulated
lubricant package and is substantially free of active sulfur. By
"soluble" or "oil soluble" is meant that the compound is oil
soluble or solubilized under normal blending conditions into the
lubrication oil or concentrate thereof. "Active" sulfur is sulfur
which is not fully oxidized. Active sulfur further oxidizes and
becomes more acidic in the oil upon use. Illustratively, sulfur
such as divalent sulfur is active sulfur whereas the sulfur in a
sulfonate group is fully oxidized and thus non-active sulfur. It is
preferred however that the molybdenum compound be substantially
free of all sulfur. By "substantially free" we mean that the
molybdenum compound contains less than about 0.5% by weight of the
material in question, e.g., active sulfur which is generally an
insufficient amount to add significantly to corrosion. The sulfur
content of some commercially available molybdenum compounds can
often have as much as about 1,000 ppm of sulfur as a contaminant
and occasionally there can be as much as 2,000 ppm of the active
sulfur. Such small amounts often come from contamination in
processing the various ingredients involved. By "alkphenyl" or
"alkaryl" we mean a phenyl or aryl group, respectively, which
contains an alkyl substituent.
Oil soluble molybdenum compounds prepared from a molybdenum source
such as ammonium molybdates, alkali and alkaline earth metal
molybdates, molybdenum trioxide, and molybdenum acetylacetonates
and an active hydrogen compound such as alcohols and polyols,
primary and secondary amines and polyamines, phenols, ketones,
anilines, etc. can be used in combination with the diarylamines in
this invention. The following listing provides examples of some
molybdenum compounds which are substantially free of active sulfur
and that may be used in combination with diarylamines in this
invention: 1. Glycol molybdate complexes as described by Price et
al in U.S. Pat. No. 3,285,942 of Nov. 15, 1966; 2. Overbased alkali
metal and alkaline earth metal sulfonates, phenates and salicylate
compositions containing molybdenum such as those disclosed and
claimed by Hunt et al in U.S. Pat. No. 4,832,857 of May 23, 1988
which is incorporated herein by reference in its entirety. The
sulfur in the compounds of Hunt et al does not provide antioxidant
protection in the oil, i.e., the activity of the sulfur is
deactivated by the overbased nature of these additives. Indeed, it
is generally known that the molybdenum-free sulfonates act as
pro-degradants in the oil (Atmospheric Oxidation and Stabilization"
by T. Colclough page 49). The main purpose for adding the
molybdenum-free overbased sulfonates is to provide detergency. When
used in combination with diarylamines, the overbased molybdenum
sulfonates such as those described by Hunt et al are expected to
provide synergistic antioxidant protection to lubricants. The
molybdenum containing overbased alkaline earth metal and alkali
metal sulfonates, phenates, and salicylates are prepared by a
process which comprises: (a) introducing into a reaction zone a
compound selected from the group consisting of a sulfonate, a
phenate, and a salicylate wherein said compound is an overbased
alkaline earth or alkali metal compound; (b) adding to said
reaction zone a solvent to solubilize said compound and to form a
mixture A; (c) heating said mixture A to an elevated temperature of
120.degree. F. or less; (d) preparing an aqueous solution of a
molybdenum compound at a temperature of 120.degree. F. or less; (e)
adding said aqueous solution of said molybdenum compound to said
mixture A with stirring during a period of about 15 minutes or less
to form a mixture B; (f) adding said mixture B containing said
molybdenum compound to a non-polar compound at a temperature of
220.degree. F. or greater within a period of up to 40 minutes
wherein resulting mixture C during said addition is at a
temperature of a least 220.degree. F.; (g) driving off said water
and said non-polar compound as overhead by increasing temperature
of said mixture C containing said molybdenum compound to about
240.degree. F. to about 300.degree. F. to obtain a water-free
composition; (h) adding additional quantity of a non-polar compound
to said water-free composition to dilute said composition to
clarify said composition by filtration or centrifugation; (i)
heating said clarified composition to a temperature of from about
300.degree. F. to about 400.degree. F. to remove solvent and said
non-polar compound and to recover product comprising an overbased
molybdenum-containing alkaline earth metal or alkali metal
compound. 3. Molybdenum complexes prepared by reacting a fatty oil,
a diethanolamine and a molybdenum source as described by Rowan et
al in U.S. Pat. No. 4,889,647 of Dec. 26, 1989; 4. Molybdenum
containing compounds prepared from fatty acids and
2-(2-aminoethyl)aminoethanol as described by Karol in U.S. Pat. No.
5,137,647 of Aug. 11, 1992; 5. Overbased molybdenum complexes
prepared from amines, diamines, alkoxylated amines, glycols and
polyols as described by Gallo et al in U.S. Pat. No. 5,143,633 of
Sep. 1, 1992; and 6. 2,4-Heteroatom
substituted-molybdena-3,3-dioxacycloalkanes as described by Karol
in U.S. Pat. No. 5,412,130 of May 2, 1995.
Molybdenum salts such as the carboxylates are a preferred group of
molybdenum compounds. The molybdenum salts used in this invention
may be completely dehydrated (complete removal of water during
preparation), or partially dehydrated. They may be salts of the
same anion or mixed salts, meaning that they are formed from more
than one type of acid. Illustrative of suitable anions there can be
mentioned chloride, carboxylate, nitrate, sulfonate, or any other
anions.
The molybdenum carboxylates may be derived from any organic
carboxylic acid. The molybdenum carboxylate is preferably that of a
monocarboxylic acid such as that having from about 4 to 30 carbon
atoms. Such acids can be hydrocarbon aliphatic, alicyclic, or
aromatic carboxylic acids. Monocarboxylic acids such as those of
aliphatic acids having about 4 to 18 carbon atoms are preferred,
particularly those having an alkyl group of about 6 to 18 carbon
atoms. The alicyclic acids may generally contain from 4 to 12
carbon atoms. The aromatic acids may generally contain one or two
fused rings and contain from 7 to 14 carbon atoms wherein the
carboxyl group may or may not be attached to the ring. The
carboxylic acid can be a saturated or unsaturated fatty acid having
from about 4 to 18 carbon atoms. Examples of some carboxylic acids
that may be used to prepare the molybdenum carboxylates include:
butyric acid; valeric acid; caproic acid heptanoic acid;
cyclohexanecarboxylic acid; cyclodecanoic acid; naphthenic acid;
phenyl acetic acid; 2- methylhexanoic acid; 2-ethylhexanoic acid;
suberic acid; octanoic acid; nonanoic acid; decanoic acid;
undecanoic acid; lauric acid; tridecanoic acid; myristic acid;
pentadecanoic acid; palmitic acid; linolenic acid; heptadecanoic
acid; stearic acid; oleic acid; nonadecanoic acid; elcosanoic acid;
heneicosanoic acid; docosanoic acid; and erucic acid.
A number of methods have been reported in the literature for
preparing the molybdenum carboxylates, e.g., U.S. Pat. No.
4,593,012 of Jun. 3, 1986 to Usui and U.S. Pat. No. 3,578,690 of
May 11, 1971 to Becker, both of which are incorporated herein by
reference in their entirety. The Usui patent describes the
production of hydrocarbon soluble salts (molybdenyl carboxylates)
by reaction of an ammonium molybdate with a carboxylic acid in the
presence of an organic amine at specified elevated temperatures
while removing water. U.S. Pat. No. 3,578,690 prepares its
molybdenum carboxylates by reacting molybdenum oxide, molybdenum
halide, alkali earth molybdate, alkaline earth molybdate, ammonium
molybdate or mixtures of molybdenum sources with carboxylic acids
at elevated temperatures and with removal of water.
The exact composition of the oil soluble molybdenum carboxylates
can vary. Most of the literature refers to these compounds as
molybdenum carboxylates. They have also been referred to as
molybdenum carboxylate salts, molybdenyl (Mo O.sub.2.sup.2+)
carboxylates and molybdenyl carboxylate salts, molybdenum
carboxylic acid salts, and molybdenum salts of carboxylic
acids.
The concentration of the molybdenum from the molybdenum compound in
the lubricant composition can vary depending upon the customer's
requirements and applications. The actual amount of molybdenum
added is based on the desired final molybdenum level in the
lubricating composition. From about 100 to 450 parts per million of
molybdenum are used in this invention based on the weight of the
lubricating oil composition which may be formulated to contain
additional additives and preferably about 100 to 250 parts per
million of molybdenum and particularly 125 to 250 ppm are used
based on the weight of the lubricating oil composition. The
quantity of additive, e.g., molybdenum carboxylate to provide
molybdenum, is based on the total weight of the formulated or
unformulated lubricating oil composition.
The secondary diarylamines are well known antioxidants and there is
no particular restriction on the type of secondary diarylamine used
in the invention. Preferably, the secondary diarylamine antioxidant
has the general formula: ##STR00001## wherein R.sup.1 and R.sup.2
each independently represents a substituted or unsubstituted aryl
group having from 6 to 30 carbon atoms. Illustrative of
substituents for the aryl there can be mentioned aliphatic
hydrocarbon groups such as aryl having from about 1 to 20 carbon
atoms, hydroxy, carboxyl or nitro, e.g., an alkaryl group having
from 7 to 20 carbon atoms in the alkyl group. The aryl is
preferably substituted or unsubstituted phenyl or naphthyl,
particularly wherein one or both of the aryl groups are substituted
with an alkyl such as one having from 4 to 18 carbon atoms. It is
further preferred that both aryl groups be substituted, e.g. alkyl
substituted phenyl.
The secondary diarylamines used in this invention can be of a
structure other than that shown in the above formula which shows
but one nitrogen atom in the molecule. Thus, the secondary
diarylamine can be of a different structure provided that at least
one nitrogen has 2 aryl groups attached thereto, e.g., as in the
case of various diamines having a secondary nitrogen atom as well
as two aryls on one of the nitrogens. The secondary diarylamines
used in this invention preferably have antioxidant properties in
lubricating oils, even in the absence of the molybdenum
compound.
The secondary diarylamines used in this invention should be soluble
in the formulated crankcase oil package. Examples of some secondary
diarylamines that may be used in this invention include: diphenyl
amine; various alkylated diphenylamines, 3-hydroxydiphenylamine;
N-phenyl-1,2-phenylenediamine; N-phenyl-1,4-phenylenediamine;
dibutyldiphenylamine; dioctyldiphenylamine; dinonyldiphenylamine;
phenyl-alpha-naphthylamine; phenyl-beta-naphthylamine;
diheptyldiphenylamine; and p-oriented styrenated diphenylamine.
The concentration of the secondary diarylamine in the lubricating
composition can vary depending upon the customer's requirements and
applications. A practical diarylamine use range in the lubricating
composition is from about 750 parts per million to 5,000 parts per
million (i.e. 0.075 to 0.5 wt %), preferably the concentration is
from 1,000 to 4,000 parts per million (ppm) and particularly from
about 1,200 to 3,000 ppm by weight. Quantities of less than 750 ppm
have little or minimal effectiveness whereas quantities larger than
5,000 ppm are not economical.
Preferably, the quantity of molybdenum in relation to the quantity
of the secondary amine should be within a certain ratio. The
quantity of molybdenum should be about 0.020 to 0.6 parts by weight
for each part by weight of the amine in the lubricating oil
composition. Preferably, this ratio will be from about 0.040 to
0.40 parts of the molybdenum per part of the amine and particularly
about 0.05 to 0.3 parts of the molybdenum per part of the amine.
The total quantity of molybdenum and amine can be provided by one
or more than one molybdenum or amine compound.
The composition of the lubricant oil can vary significantly based
on the customer and specific application. In general, the oil is a
formulated oil which is composed of between 75 and 95 wt % of a
mineral lubrication oil, between 0 and 10 wt % of a polymeric
viscosity index improver, and between about 5 and 15 wt % (weight
percent) of an additive package. The additive package generally
contains the following components: (a). Dispersants. The
dispersants are nonmetallic additives containing nitrogen or oxygen
polar groups attached to a high molecular weight hydrocarbon chain.
The hydrocarbon chain provides solubility on the hydrocarbon base
stocks. The dispersant functions to keep oil degradation products
suspended in the oil. Examples of commonly used dispersants include
copolymers such as polymethacrylates and styrenemaleinic ester
copolymers, substituted succinamides, polyamine succinamides,
polyhydroxy succinic esters, substituted mannich bases, and
substituted triazoles. Generally, the dispersant is present in the
finished oil between about 4.0 and 8.5 wt %. (b). Detergents. The
detergents are metallic additives containing charged polar groups,
such as sulfonates or carboxylates, with aliphatic, cycloaliphatic,
or alkylaromatic chains, and several metal ions. The detergents
function by lifting deposits from the various surfaces of the
engine. Examples of commonly used detergents include neutral and
overbased alkali and alkaline earth metal sulfonates, neutral and
overbased alkali and alkaline earth metal phenates, sulfurized
phenates, overbased alkaline earth salicylates, phosphonates,
thiopryophosphonate, and thiophosphonates. Generally, the
detergents are present in the finished oil between about 1.0 and
2.5 wt %. (c). ZDDP's. The ZDDP's (zinc dihydrocarbyl
dithiophosphates) are the most commonly used antiwear additives in
formulated lubricants. These additives function by reaction with
the metal surface to form a new surface active compound which
itself is deformed and thus protects the original engine surface.
Other examples of anti-wear additives include tricresol phosphate,
dilauryl phosphate, sulfurized terpenes and sulfurized fats. The
ZDDP's also function as antioxidants. Generally, the ZDDP is
present in the finished oil between about 1.0 and 1.5 wt %,
although when used, they can be used at substantially lower
concentrations, e.g., 0.5 wt %. It is desirable from environmental
concerns to have lower levels of ZDDP. (d). Antioxidants. In
molybdenum-free oils other antioxidants in addition to the zinc
dihydrocarbyl dithiophosphates are used to protect the oil from
oxidative degradation. The amount of supplemental antioxidant will
vary depending on the oxidative stability of the base stock.
Typical treat levels in finished oils can vary from about 1.0 to
2.5 wt %. The supplementary antioxidants that are generally used
include hindered phenols, hindered bisphenols, sulfurized phenols,
alkylated diphenylamines, sulfurized olefins, alkyl sulfides and
disulfides, dialkyl dithiocarbamates, and phenothiazines. The
inclusion of molybdenum carboxylates with diphenylamines removes
the need for these supplementary antioxidants. However, a
supplementary antioxidant may be included in oils that are less
oxidatively stable or in oils that are subjected to unusually
severe conditions.
The lubrication oil component of this invention may be selected
from any of the synthetic or natural oils used as lubricants such
as that for crankcase lubrication oils for spark-ignited and
compression-ignited internal combustion engines, for example
automobile and truck engines, marine, and railroad diesel engines.
Synthetic base oils include alkyl esters of dicarboxylic acids,
polyglycols and alcohols, poly-alpha-olefins, including
polybutenes, alkyl benzenes, organic esters of phosphoric acids,
and polysilicone oils.
Natural base oils include mineral lubrication oils which may vary
widely as to their crude source, e.g., as to whether they are
paraffinic, naphthenic, or mixed paraffinic-naphthenic.
The lubrication oil base stock conveniently has a viscosity of
about 2.5 to about 15 cSt or mm.sup.2/s and preferably about 2.5 to
about 11 cSt or mm.sup.2/s at 100.degree. C.
A polymeric viscosity index improver (VII) component may be used in
this invention and such component may be selected from any of the
known viscosity index improvers. The function of the VII is to
reduce the rate of change of viscosity with temperature, i.e. they
cause minimal increase in engine oil viscosity at low temperature
but considerable increase at high temperature. Examples of
viscosity index improvers include polyisobutylenes,
polymethacrylates, ethylene/propylene copolymers, polyacrylates,
styrene/maleic ester copolymers, and hydrogenated styrene/butadiene
copolymers.
In addition to the lubricant additives mentioned thus far, there is
sometimes a need for other supplemental additives that perform
specific functions not provided by the main components. These
additional additives include, pour point depressants, corrosion
inhibitors, rust inhibitors, foam inhibitors, and supplemental
friction modifiers.
The lubricating oil compositions of this invention can be made by
adding the molybdenum additive and the secondary diarylamine
additive in a lubrication oil composition. In the case of a
formulated oil, the composition can also contain additional
additives such as dispersants, detergents, zinc dihydrocarbyl
dithiophosphates, and still additional antioxidants. The method or
order of component addition is not critical. Alternatively, the
combination of molybdenum and amine additives can be added to the
lubrication oil as a concentrate with or without such concentrate
containing the remaining additives.
The lubricating oil concentrate will comprise a solvent and from
about 2.5 to 90 weight percent (wt %) and preferably 5 to 75 wt %
of the combination of the molybdenum additive and amine additive of
this invention. The solvent may be that of hydrocarbon oils, e.g.,
mineral lubrication oil or a synthetic oil. The ratio of molybdenum
to amine in the concentrate composition is from about 0.02 to 0.6
parts of molybdenum per part of amine and preferably from about
0.04 to 0.4 parts of molybdenum for each part of the amine by
weight. In addition to the molybdenum and amine additives of this
invention, the concentrate may contain additional additives as is
conventional in the art, e.g., dispersants, detergents, and zinc
dihydrocarbyl dithiophosphates.
There are a number of recent trends in the petroleum additive
industry that may restrict, and/or limit, the use of certain
additives in formulated crankcase oils. The key trends are the move
to lower phosphorus levels in the oil, the new fuel economy
requirements and the move to more severe engine test conditions for
qualifying oils. Such changes may show that certain currently used
antioxidant additives are no longer effective in protecting the oil
against oxidation. The molybdenum/diarylamine based antioxidant
mixture disclosed herein provides a solution to this need.
Furthermore, there is concern that phosphorus from the lubricant
tends to poison catalyst used in catalytic converters, thereby
preventing them from functioning to full effect. Also, active
sulfur containing antioxidants, including active sulfur containing
molybdenum compounds are known to cause copper corrosion. This is
generally known and has been disclosed by T. Colclough in
Atmospheric oxidation and Antioxidants, Volume II, chapter 1,
Lubrication Oil Oxidation and Stabilization. G. Scott, editor, 1993
Elsevier Science Publishers.
The molybdenum compound in this invention is preferably
substantially free of phosphorus and substantially free of active
sulfur and it is particularly preferred to have the molybdenum
compound substantially free of sulfur whether active or
otherwise.
The following examples are illustrative of the invention and its
advantageous properties. In these examples as well as elsewhere in
this application, all parts and percentages are by weight unless
otherwise indicated.
EXAMPLE 1
The following example shows the antioxidant synergism that exist;
when molybdenum naphthenate and a diphenylamine are formulated into
an SAE Grade 5W-30 type motor oil. The example also shows that this
antioxidant behavior is unique when compared to other metals.
A variety of oil soluble metals and one diphenylamine type
antioxidant were blended into a SAE Grade 5W-30 type motor oil as
shown in Table 1. The only additional antioxidant in these blends
was the zinc dialkyldithiophosphate. The oxidation stability of
these oils was measured by pressurized differential scanning
calorimetry (PDSC) as described by J. A. Walker and W. Tsang in
"Characterization of Lubrication Oils by Differential Scanning
Calorimetry", SAE Technical Paper Series. 801383 (Oct. 20-23,
1980). Oil samples were treated with an iron (III) acetylacetonate
catalyst (55 ppm Fe) and 2 milligrams (mg) were analyzed in an open
aluminum hermetic pan. The DSC cell was pressurized with 500 psi
air and programmed with the following heating sequence: (1) jump
from ambient to 165.degree. C. (2) jump from 165.degree. C. to
175.degree. C. at 2 C/min, (3) isothermal at 175.degree. C. The oil
samples were held at 175.degree. C. until an exothermic release of
heat was observed. The exothermic release of heat marks the
oxidation reaction. The time from the start of the experiment to
the exothermic release of heat is called the oxidation induction
time and is a measure of the oxidative stability of the oil (i.e.
the longer the oxidation induction time the greater the oxidative
stability of the oil). All oils are evaluated in duplicate and the
results averaged. As shown in Table 1 the oil samples containing
both molybdenum naphthenate and diphenylamine had the longest
oxidation induction times. These oil samples also contain other
metals. In order to rule out the possibility of the other metal
contributing to the improved oxidative stability of the oils, the
oxidation induction time data was analyzed for main and interaction
effects as described by G. E. P. Box, W. G. Hunter, and J. S.
Hunter in "Statistics for Experiments", 1978, John Wiley &
Sons. The results are provided in Table IA. The results show the
following: 1. The improved oxidative stability of the oil is
predominantly due to the presence of molybdenum naphthenate and
diphenylamine. 2. There is a strong interaction effect, i.e.
synergism, between molybdenum naphthenate and the
diphenylamine.
The other metals show very little effect, or a negative effect, on
the oxidative stability of the oil. In addition, the other metals
show no interaction effect, or a negative interaction effect, with
the diphenylamine.
In the below Tables I and IA: Ce Nap is cesium naphthenate; Co Nap
is cobalt naphthenate; Ni Oct is nickel octanoate; and Mo Nap is
molybdenum naphthenate. The concentration of metallic additives is
expressed in parts per million of the metal. DPA is
dinonyldiphenylamine which is expressed in percent by weight, e.g.
0.1 wt % being 1,000 ppm; Induction Time is the DSC Induction Time
in minutes as an average.
TABLE-US-00001 TABLE I PDSC Induction Times for Motor Oil Blends
Concentration of Additives In SAE Grade 5W-30 Type Motor Oil* Oil
Ce Co Ni Mo Process Induction No. Nap Nap Oct Nap DPA Oil Wt. %
Time 1 0 0 0 0 0.10 1.50 41.8 2 200 0 0 0 0.00 1.27 16.5 3 0 200 0
0 0.00 1.27 26.4 4 200 200 0 0 0.10 0.83 26.5 5 0 0 200 0 0.00 1.35
16.1 6 200 0 200 0 0.10 0.92 28.1 7 0 200 200 0 0.10 0.92 33.5 8
200 200 200 0 0.00 0.68 22.7 9 0 0 0 200 0.00 1.27 24.7 10 200 0 0
200 0.10 0.83 60.1 11 0 200 0 200 0.10 0.83 62.5 12 200 200 0 200
0.00 0.60 34.6 13 0 0 200 200 0.10 0.92 72.4 14 200 0 200 200 0.00
0.68 26.0 15 0 200 200 200 0.00 0.68 40.9 16 200 200 200 200 0.10
0.25 54.2 *A formulated crankcase oil containing 83.2 wt % base
oil, 6.2 wt % polymeric viscosity index improver, 6.9 wt % ashless
dispersant, 2.1 wt % calcium, sodium & magnesium overbased
& neutral detergents, and 1.2 wt % zinc
dialkyldithiophosphate.
TABLE-US-00002 TABLE IA Main Effects and Interaction Effects On
PDSC Oxidation Induction Time Main Effect Interaction Effect
Factors and Interactions (minutes) (minutes) Ce Nap -6.2 Co Nap 2.0
Ni Oct 0.1 Mo Nap 20.5 DPA 21.4 Ce Nap with Co Nap -0.2 Ce Nap with
Ni Oct -1.8 Ce Nap with Mo Nap -0.2 Co Nap with Ni Oct 0.2 Co Nap
with Mo Nap 0.3 Ni Oct with Mo Nap 2.8 Mo Nap with DPA 9.4 Ni Oct
with DPA -0.8 Co Nap with DPA -8.4 Ce Nap with DPA -4.1
EXAMPLE 2
Molybdenum naphthenate and alkylated diphenylamine, Naugalube 680,
from Uniroyal Chemical Company; were blended into an SAE Grade
5W-30 type motor oil as shown in Table II. The only additional
antioxidant in these blends was the zinc dialkydithiophosphate. The
oxidation stability of these oils was measured by pressurized
differential scanning calorimetry (PDSC) as described in Example 1.
These oils were also subjected to the following hot oil oxidation
test: Into 25 grams (g) of each motor oil was blended 0.8 g of a
catalyst mixture containing 5.55 wt % iron (III) naphthenate (6 wt
% Fe content) and 94.45 wt % xylenes. Dry air was blown through the
oil at rates of 10 Liters (L)/hour (h) while maintaining the
temperature at 160.degree. C. for a period of 72 hours. The oil was
cooled and the percent change in viscosity between the new oil and
the oxidized oil was determined at 40.degree. C. A lower percent
change in viscosity for an oil is an indication of less oil
degradation and thus better oxidation control by the additives. All
oils were evaluated in duplicate and the results averaged. Results
from the PDSC and the hot oil oxidation test are found in Table II.
Both the PDSC results and the hot oil oxidation test results show
that the combination of molybdenum naphthenate (Mo-Nap) and
alkylated diphenylamine (N-680) provides superior oxidation control
versus use of these additives separately. Note that for the samples
containing a combination of molybdenum naphthenate and the
diphenylamine the measured oxidation induction time values are
significantly larger than the expected values. The expected values
are what one would observe if there was no synergism between the
molybdenum naphthenate and the diphenylamine, i.e. the additives
act independently of each other. Expected values are calculated by
adding the increase in induction time due to the individual
additives. The much larger measured induction time values versus
the expected values clearly show the molybdenum
naphthenate/diphenylamine synergism. In the following Table II, the
concentration of the molybdenum naphthenate is expressed in ppm of
molybdenum whereas the concentration of the N-680 Amine is
expressed in weight percent, i.e. 0.1 wt % is equal to 1,000 ppm.
The oxidation induction time by PDSC in minutes is in the column
headed as "Induction Time". The OIT expected response in minutes is
in the column under "Expected Time"; the viscosity increase from 72
hour HOOT (%) is an average of duplicate runs and is under the
column headed "Viscosity Increase".
TABLE-US-00003 TABLE II Oxidative Stability of Motor Oil Blends* by
PDSC and the Hot Oil Oxidation Test Concentration of Additives
Process Induc- Oil Mo Nap N-680 Oil tion Expected Viscosity # (As
ppm Mo) Wt % Wt % Time Time Increase 1 0 0.000 1.25 28.4 28.4
303.18 2 125 0.000 1.04 35.1 35.1 671.48 3 250 0.000 0.83 33.0 33.0
362.22 4 0 0.075 1.18 44.9 44.9 44.64 5 125 0.075 0.97 63.5 51.6
36.93 6 250 0.075 0.76 73.0 49.5 66.10 7 0 0.150 1.10 62.5 62.5
31.61 8 125 0.150 0.89 107.8 69.2 11.93 9 250 0.150 0.68 108.7 67.1
10.02 *A formulated crankcase oil containing 83.2 wt % base oil,
6.2 wt % polymeric viscosity index improver, 6.9 wt % ashless
dispersant, 2.1 wt % calcium, sodium, and magnesium overbased and
neutral detergents, and 1.2 wt % zinc dialkyldithiophosphate.
EXAMPLE 3
The following example shows that other classes of amines, e.g.,
certain substituted amines, disubstituted phenylene diamines, and
alkyl amines, are not effective or minimally effective at
controlling oxidation when used in combination with molybdenum
carboxylates.
Molybdenum naphthenate and a variety of amines, were blended into
an SAE Grade 5W-30 type motor oil (formulated crankcase oil as
described in Example 2) as shown in Table III and as further
described below. The only additional antioxidant in these blends
was the zinc dialkyl dithiophosphate. The oxidation stability of
these oils was measured by pressurized differential scanning
calorimetry (PDSC) as described in Example 1. These oils were also
subjected to the hot oil oxidation test described in Example 2.
Both the hot oil oxidation test results (small percentage changes
in viscosity) and the PDSC test results (prolonged oxidation
induction times) show that the combination of molybdenum
naphthenate and alkylated diarylamines is more effective than the
individual additives. Phenylnaphthyl amines show some effectiveness
when used in combination with molybdenum naphthenate. The
substituted anilines, substituted phenylene diamines, and alkyl
amines, were much less effective when used in combination with
molybdenum naphthenate. In fact, the hot oil oxidation test results
show that many of these other amines show a prodegradant effect
(large percent changes in viscosity versus oil #0) when used in
combination with molybdenum naphthenate.
The results of the tests of Example 3 are shown in Table III. In
Table III, the first column is the test number involved. The column
headed "A" shows the concentration of molybdenum naphthenate
expressed in ppm of molybdenum. The remaining columns "B" through
"J" show concentrations in weight percent wherein column "B" is
that of dinonyl diphenylamine; column "C" is an alkylated
diphenylamine trade named Naugalube 680, from Uniroyal Chemical
Company; "D" is phenyl -alpha-naphthylamine; "E" is disecbutyl
phenylenediamine; "F" is 4-tetradecylaniline; "G" is
2,5-di-t-butylaniline; "H" is 2,6-diisopropyl aniline; "I" is
di-n-decylamine; and "J" is that of process oil. The results of
these tests are shown in Table IIIA wherein for each of the
numbered oil samples there is shown the results of the tests of
Table III.
TABLE-US-00004 TABLE III Oxidation of Motor Oils Containing
Molybdenum Naphthenates and Amines Concentration of additives in
SAE Grade 5W-30 Type Motor Oil* Oil A B C D E F G H I J 0 0 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.25 1 200 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.92 2 0 0.10 0.00 0.00 0.00 0.00 0.00 0.00
0.00 1.15 3 200 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.82 4 0
0.00 0.10 0.00 0.00 0.00 0.00 0.00 0.00 1.15 5 200 0.00 0.10 0.00
0.00 0.00 0.00 0.00 0.00 0.82 6 0 0.00 0.00 0.10 0.00 0.00 0.00
0.00 0.00 1.15 7 200 0.00 0.00 0.10 0.00 0.00 0.00 0.00 0.00 0.82 8
0 0.00 0.00 0.00 0.10 0.00 0.00 0.00 0.00 1.15 9 200 0.00 0.00 0.00
0.10 0.00 0.00 0.00 0.00 0.82 10 0 0.00 0.00 0.00 0.00 0.10 0.00
0.00 0.00 1.15 11 200 0.00 0.00 0.00 0.00 0.10 0.00 0.00 0.00 0.82
12 0 0.00 0.00 0.00 0.00 0.00 0.10 0.00 0.00 1.15 13 200 0.00 0.00
0.00 0.00 0.00 0.10 0.00 0.00 0.82 14 0 0.00 0.00 0.00 0.00 0.00
0.00 0.10 0.00 1.15 15 200 0.00 0.00 0.00 0.00 0.00 0.00 0.10 0.00
0.82 16 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.10 1.15 17 200 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.10 0.82 *A formulated crankcase oil
containing 83.2 wt % base oil, 6.2 wt % polymeric viscosity index
improver, 6.9 ashless dispersant, 2.1 wt % calcium, sodium and
magnesium overbased & neutral detergent, and 1.2 wt % zinc
dialkyldithiophosphate.
TABLE-US-00005 TABLE IIIA Oxidation Induction Time Viscosity
Increase By PDSC (min) From 72 h HOOT (%) Oil # Avg From Duplicate
Runs Avg From Duplicate Runs 0 41.8 510.6 1 54.0 1650.2 2 72.9 89.3
3 111.2 59.5 4 81.8 68.3 5 102.8 48.8 6 66.8 129.1 7 74.3 102.2 8
61.3 150.6 9 62.6 417.3 10 40.8 728.1 11 41.8 1387.4 12 40.3 534.2
13 48.2 1058.8 14 34.2 463.2 15 46.2 561.7 16 39.9 305.0 17 39.7
905.8
EXAMPLE 4
Molybdenum octoate and alkylated diphenylamine, Naugalube 680, from
Uniroyal Chemical Company, were blended into an SAE grade 5W-30
type motor oil as shown in Table IV. The only additional
antioxidant in these blends was the zinc dialkydithiophosphate. The
frictional properties of these oils were measured using the High
Frequency Reciprocating Rig. In this instrument 1-2 mls
(milliliters) of a sample oil are placed in a temperature
controlled steel pan. A steel ball attached to a movable arm is
lowered into the pan. A load of 400 g is applied to the steel
ball/arm assembly. The steel/ball arm assembly is oscillated at 20
Hz over a 1 mm (millimeter) path length. As the arm is oscillated,
a friction coefficient is determined every 5 seconds. The test
lasts 3 minutes so approximately 30 data points are averaged to
determine the friction coefficient of an oil in a given test. A
reduction in the friction coefficient corresponds to improved
friction properties of the oil. Duplicate tests were performed on
each oil at 70.degree. C., 100.degree. C., and 130.degree. C. The
average friction coefficient and standard deviation (SD) for each
sample are shown in Table IV.
It can be seen from Table IV that an improvement in friction
properties (lower coefficient of friction) results when the
concentration of molybdenum octoate is increased in the oil.
Reference oil 5 (R5) shows that a conventional antioxidant is not
as effective as a friction modifier compared to molybdenum
octanoate.
In Table IV: "Mo-Oct." is molybdenum octoate; "N-680" is alkylated
diphenylamine; "t-Bu" is t-butylphenols; and "PO" is process
oil.
TABLE-US-00006 TABLE IV Frictional Properties Of Motor Oil Blends
using the High Frequency Reciprocating Rig Test Concentration of
additives in SAE GRADE 5W-30 TYPE MOTOR OIL Mo- A- Oct N-680 t-Bu
P.O. FRICTION COEFFICIENT Oil ppm wt % wt % wt % 70 C SD 100 C SD
130 C SD R1 0 0 0 0 0.117 0.001 0.116 0.001 0.116 0.001 2 204 0.125
0 0.375 0.117 0.001 0.113 0.002 0.113 0.001 3 319 0.125 0 0 0.110
0.001 0.104 0.004 0.106 0.004 4 432 0.125 0 0 0.105 0.001 0.095
0.001 0.092 0.001 R5 0 0.125 0.70 0.375 0.125 0.001 0.128 0.002
0.127 0.003
EXAMPLE 5
This example shows that the benefit of the molybdenum/diphenylamine
combination requires using at least 100 ppm of the molybdenum. As
shown in Example 6, this enhanced oxidation performance starts to
break down at extremely high levels( greater than 400 ppm) of
molybdenum.
Molybdenum 2-ethylhexanoate, containing 13.0 wt % molybdenum and
alkylated diphenylamine, Naugalube 680, from Uniroyal Chemical
Company, were blended into an SAE grade 5W-30 motor oil as shown in
Table V below. The control 5W-30 motor oil contained the following
additives:
TABLE-US-00007 Formulated Motor Oil Components Weight % ZDDP 1.1
Ashless dispersant 7.0 Viscosity Index Improver 7.0 Neutral &
Overbased Detergents 1.4 Pour Point Depressant 0.5 Diluent Oil
83.0
The oxidative stability of these oils was measured by using the
following Hot Oil Oxidation Test:Into 25 g of each motor oil was
blended 0.8 g of catalyst mixture containing 5.55 wt % Iron (III)
Naphthenate (6 wt % Fe content) and 94.45 wt % xylenes. Dry air was
blown through the oil at a rate of 10 L/h (liters per hour) while
maintaining the temperature at 160.degree. C. for a period of 64
hours. The oil was cooled and the percent change in viscosity
between the new oil and the oxidized oil was determined at
40.degree. C. The lower percent change in viscosity for an oil is
an indication of less oil degradation and thus better oxidation
control by the additives. The abbreviation "% vise Incr" in Table V
relates to percent viscosity increase. All oils were evaluated in
duplicate and the results averaged. The results are found in Table
V.
TABLE-US-00008 TABLE V Oxidative Stability of Motor Oil Blends By
the Hot Oil Oxidation Test Molybdenum Amine 2-ethyl- % Viscosity
Increase Change N-680 hexanoate After 74 h % Visc Sample wt % ppm
Mo in the HOOT Incr 0 0.15 0 70 0 1 0.15 52 69 -1 2 0.15 104 68 -2
3 0.15 156 49 -21 4 0.15 208 43 -27 5 0.15 260 46 -24 6 0.15 312 35
-35 7 0.15 364 32 -38 8 0.15 416 27 -43 9 0.15 468 23 -47
The viscosity results in the above table clearly show that at
molybdenum level of 104 ppm, the molybdenum/diarylamine combination
showed but a small improvement for the oxidative stability of the
oil. However, at molybdenum levels greater than 104 such as 156
ppm, a significant improvement in oxidation control is seen. The
largest improvement occurs between 104 ppm and 156 ppm molybdenum
content.
EXAMPLE 6
A sample of molybdenum octoate was diluted with paraffin oil,
blended at 50.degree. C. for 1 hour and filtered using a pressure
filtration apparatus. The molybdenum content of the filtered oil
was determined to be 2.91 wt %.
The diluted and filtered molybdenum octoate sample described above,
and alkylated diphenylamine, Naugalube 680, from Uniroyal Chemical
Company, were blended into an SAE grade 5W-30 type motor oil as
shown in Table VI. The control 5W-30 motor oil contained the
components specified in Example 5 above. The oxidative stability of
these oils was measured using the Hot Oil Oxidation Test described
in Example 5. All oils were evaluated in duplicate and the results
averaged. The results are found in Table VI.
TABLE-US-00009 TABLE VI Oxidative Stability of Motor Oil Blends By
The Hot Oil Oxidation Test Amine % Viscosity Change % Sample Wt %
PPM Mo Increase Viscosity 1 0.125 0 55 0 2 0.125 204 35 -20 3 0.125
318 27 -28 4 0.125 432 133 78
The viscosity results of the above Table VI clearly show that if a
sufficient amount of amine is not present, a high molybdenum
content becomes detrimental to the oxidative stability of the oil.
In this example 0.125% amine with 318 ppm molybdenum provides good
antioxidant protection. Increasing the molybdenum level to 432 ppm
is not as effective as the lower concentrations to the oxidative
stability of the oil (large increase in viscosity).
EXAMPLE 7
A series of lubrication formulations in accordance with this
invention were tested in the Sequence IIIE engine test. The IIIE
test uses a 231 CID (3.8 liter) Buick V-6 engine at high speed
(3,000 rpm) and a very high oil temperature of 149.degree. C. for
64 hours. This test is used to evaluate an engine oil's ability to
minimize oxidation, thickening, sludge, varnish, deposits, and
wear. The formulations contained 7.0 wt % viscosity index improver,
7.0 wt % ashless dispersant, 1.1 wt % ZDDP, 1.4 wt % detergents,
0.5 wt % supplemental additives, with the remainder being mineral
oil. The addition of supplemental antioxidants are indicated in
Table VII along with the engine test results. Hindered, mixed
t-butylphenol antioxidant, referred at as "Phenolic" in Table VII
below and a secondary alkylated diphenylamine, referred to as
"Amine" in Table VII below disclosed for use in this invention are
commercially available. Formulation A, also simply referred to in
the table as "A" contained no molybdenum. The molybdenum source in
formulation B, simply referred to as "B" in the table is molybdenum
octoate available from Shepherd Chemical Company. The molybdenum
source in formulation C, simply referred to as "C" in the table, is
molybdenum 2-ethylhexanoate available from OM Group. TVTM indicates
that the oils viscosity was too viscous to measure and represents a
severe failing result in the IIIE engine. Some of the abbreviations
used in the below Table VII are as follows: "% Visc. Inc.@ 64 h"
means percent viscosity increase in 64 hours; "AE Sludge" is
average engine sludge rating; "APS Varnish" is average piston skirt
varnish; "ORL Deposit" is oil ring land deposit; "AC Wear" is
average cam wear; MC Wear is maximum cam wear; and "L" is
liters.
TABLE-US-00010 TABLE VII Sequence IIIE Evaluation of
Molybdenum/Secondary Diphenylamine Antioxidants Passing Result
Limits A B C Phenolic Content (wt %) 0.7 0 0 Amine Content (wt %)
0.1 0.125 0.2 Molybdenum Content 0 458 115 (ppm Mo) % Vis. Inc. @
64 h 375 Max. TVTM 152 300 AE Sludge 9.2 Min. 9 9.54 9.56 APS
Varnish 8.9 Min. 7.96 9.1 9.38 ORL Deposit 3.5 Min. 2.53 4.38 4.8
Stuck Ring 2 2 1 AC Wear 30 Max. 7.2 7.8 6.5 MC Wear 64 Max. 15.0
12.00 11.00 Oil Consumption in Liters 5.1 Max 4.35 3.32 3.35
The results of the above Table VII clearly show that the
conventional phenolic antioxidant in Formulation A is ineffective
in combination with the diphenylamine at controlling viscosity and
passing the IIIE engine test. The molybdenum/diphenylamine
combination in formulations B and C is very effective at both
controlling viscosity and passing the engine test.
EXAMPLE 8
This example shows that the molybdenum carboxylate/diphenylamine
combination is also effective in lubricants that do not contain
additional additives. Alkylated diphenylamine, Naugalube 680, from
Uniroyal Chemical Company, and molybdenum HEX-CEM, from OM Group,
were blended into Petro Canada Paraflex HT100 (650N) base oil as
described in Table VIII. These samples were subjected to the hot
oil oxidation test described in Example 2 with the only change
being that the heating period was reduced from 72 hours to 40
hours. The oils were cooled and the percent change in viscosity
between the new oil and the oxidized oil was determined at
40.degree. C. The results are shown in Table VIII below.
TABLE-US-00011 TABLE VIII Hot Oil Oxidation of Unadditized Base Oil
In the Presence and Absence of Molybdenum. Base Oil N-680 Mo
HEX-CEM % Change Visc. Oil # (wt %) (wt %) (ppm Mo) After 40 h 1
99.75 0.25 0 318 2 99.65 0.25 130 -2 3 99.55 0.25 260 1
It can be seen from the above Table VIII that significant
improvement in oxidative stability of unadditized base oil occurs
when a molybdenum carboxylate is combined with a secondary
diarylamine.
EXAMPLE 9
The following example shows antioxidant synergism between
molybdenum and a diarylamine wherein the molybdenum compound is not
a carboxylate.
Molyvan 855, a sulfur and phosphorus free organic amide molybdenum
complex supplied by R. T. Vanderbilt Company, Inc. (CAS Reg. No.
64742-52-5), alkylated diphenylamine Naugalube 680, from Uniroyal
Chemical Company, and process oil were blended into an SAE Grade
5W-30 type motor oil as shown in Table IX below. The formulated oil
used in this example was the same as that used in Example 1. The
only additional antioxidant in these blends was the zinc
dialkyldithiophosphate. The oxidation stability of these oils was
measured by pressurized differential scanning calorimetry (PDSC) as
described in Example 1. These oils were also subjected to the hot
oil oxidation test described in Example 2 with the only change
being that the heating period was reduced from 72 hours to 64
hours. All oils were evaluated in duplicate or triplicate and the
results averaged. The results are found in Table IX below. Both the
PDSC results and the hot oil oxidation test results show that the
combination of the organic amide molybdenum complex and the
alkylated diphenylamine provides superior oxidation control versus
use of these additives separately. Note that for samples containing
a combination of Molyvan 855 and alkylated diphenylamine the
measured values are significantly larger than the expected values.
The expected values are what one would observe if there were no
synergism between the Molyvan 855 and the alkylated diphenylamine,
i.e., the additives act independently of each other. The much
larger measured OIT values versus the expected values clearly show
the organic amide molybdenum complex/diphenylamine synergism.
TABLE-US-00012 TABLE IX Molyvan 855 Process Added N-680 Oil
Induction Expected Viscosity Wt. % Added Added Time OIT Increase
Oil (ppm Mo) Wt % Wt % (min) (min) (%) A 0 0 1.25 26.6 201 B 0 0.1
1.15 59.4 42 C 0.272 (200) 0 0.98 50.8 548 D 0.272 (200) 0.1 0.88
106.2 83.6 25
* * * * *