Note: Descriptions are shown in the official language in which they were submitted.
: 10~7477
. .
Background
Field of the Invention
The invention is in the field of lubricating
oils which are particularly suitable for use in gas turbine
engines, including aircraft and automotive, and stationary
steam tur~ine engines.
General Back~round
It is generally recognized that the operating
; conditions of gas turbine engines expose the lubricant to
extreme conditions. In order to be satisfactory, the
lubricant must be resistant to oxidation and corrosion at
high temperatures. Moreover, the lubricant must be
resistant to deposit-formation at high temperatures.
Normally, gas turbine and steam turbine units
require different lubricant types, the former synthetic
ester-based oils and the latter petroleum oils.
We have found a particular combination of lubri-
cant additives which work in mineral lubricating oils or
synthetic hydrocarbon lubricating oils. Furthermore, the
lubricant compositions of our invention work in either
steam turbines or gas turbines. They are particularly
suitable for use in gas turbines. Because of this, our
lubricant compositions provide an important advance in the
art.
Prior Art
~ach of the lubricant additives used in our
lubricant compositions is known to be useful in lubricating
oils. However, we have found that certain synergistic
relationships are present in the additives which provide
improved results in the combinations used. For example, we
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have found that the lubricant compositions of the broad
.~ . .
aspect of our invention provide superior performance,
particularly when compared to commercially available prod-
ucts. While these compositions provide good overall test
- s results, we have found that the addition of a small amount
of the particular copolymer used in our invention provides a
: .
pronounced improvement in the test results.
srief Summary_of the Invention
Broadly stated, the present invention is directed
to a lubricating oil composition which comprises a major
amount of a mineral or synthetic hydrocarbon base oil and
an effective amount of a combination of the following
: materials: triphenyl phosphite or a trialkyl-substituted
phenyl phosphite; diphenylamine or alkylated diphenylamine;
phenyl -naphthylamine, phenyl ~-naphthylamine, alkyl or
alkaryl substituted phenyl ~-naphthylamine, or alkyl or
alkaryl substituted phenyl ~-naphthylamine; benzotriazole
or alkyl-substituted benzotriazole, partial ester of alkyl
or alkenyl succinic anhydride.
In a preferred aspect, the lubricating oil com-
position contains additionally an effective amount of a
copolymer of N-vinyl-2-pyrrolidone and an -olefin.
The lubricating oil compositions of our invention
have properties which render them particularly useful in
steam or gas turbines.
Materials Used
-- .
The base oil can be a conventionally refined
m neral lubricating oil or a synthetic hydrocarbon lubri-
cating oil. The mineral lubricating oils are well known to
those skilled in the art. Both light viscosity (e.g., pale
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~i iO47477
-~ oils) and heavy viscosity (e.g., bright stock) oils can be
used. A complete description of mineral lubricating oils
.,.
is provided by Nelson's "Petroleum Refinery Engineering"
(McGraw-Hill, New York, 1958).
Suitable synthetic hydrocarbon lubricating oils
include di-n-long-chain alkaryls, as described herelnafter,
linear mono-olefin oligomers, and a composition consisting
essentially of di-n-long-chain alkaryls and trialkyl-
substituted tetrahydronaphthalenes.
- 10 Linear mono-olefin oligomers, which are suitable
- as lubricating oils, are described in several U.S. patents,
e.g., U.S. 3,382,291, U.S. 3,149,178, and U.S. 3,808,134.
A particularly suitable linear mono-olefin
oligomer composition is prepared from -olefins containing
6 to 16 carbon atoms, more suitably 8 to 12 carbon atoms,
and preferably 10 carbon atoms. The linear mono-olefin
oligomer composition contains at least 50 weight percent,
more usually at least 60 weight percent, of materials
containing 24 to 60 carbon atoms.
The term di-n-long-chain alkaryl refers to
materials represented by the formula
R ~ A
l~L 1
wherein R and Rl are alkyl groups containing from 6 to 18
i 25 carbon atoms, more suitably from about 9 to about 15
carbon atoms, and preferably from about 10 to 14 carbon
atoms, with the sum of R and Rl being from about 20 to
about 28 carbon atoms and wherein A and Al are hydrogen or
a Cl or C~ alkyl group, but preferably are hydrogen.
Thus, the preferred di-n-long-chain alkaryl is a
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di-n-alkylbenzene wherein the alkyl group contains from
about 10 to about 14 carbon atoms.
The alkyl groups are substantially straight-chain
(thus the term n-alkaryls) wherein, preferably, at least 95
percent of the alkyl substituents are bonded to the benzene
nucleus through a secondary carbon atom of the respective
alkyl groups. While we prefer the term "n-alkaryls," other
terms such as linear alkaryls or straight-chain alkaryls
- are equally descriptive.
A particularly suitable di-n-long-chain alkaryl--
trialkyl-substituted tetrahydronaphthalene composition
typically contains the following
Component: Percent by Weight
Di-n-long-chain alkaryls61-92
Trialkyl-substituted tetrahydro-
naphthalenes 5-30
Miscellaneous alkyl aromatics:
Less than lS
Preferably less than 10
The composition is also characterized as having
- the following properties:
Viscosity index 80-116
~- Pour Point, F -40 to -80
Molecular weight range 350-526
Preferably 375-480
The di-n-long-chain alkaryls meet the description
provided in the foregoing.
The trialkyl-substituted tetrahydronaphthalenes
can be represented by the formula
, .
:
:
7477
H R
R4
R2
wherein Rl and R2 contain from 1 to about 13 carbon atoms
each, with the sum of Rl and R2 being from about 6 to
about 14 and R3 and R4 contain from 1 to about 16 carbon
atoms with the sum of R3 and R4 being from about 9 to about
17. The alkyl groups, Rl, R2, R3, and R4, are straight-
chain.
The trialkyl-substituted tetrahydronaphthalenes
have the same boiling range as the di-n-alkylbenzenes. In
addition, they have approximately the same molecular weight.
Suitable phosphites include triphenyl phosphite
and trialkyl-substituted phenyl phosphites, wherein the
phenyl moiety has 1 or 2 alkyl substituents, each of which
contains 1 to 12 carbon atoms. Examples of the latter-
: named phosphites which are suitable include triphenyl
phosphite, tritolyl phosphite, tricresyl phosphite, tri-
; hexylphenyl phosphite, tributylphenyl phosphite, and tri
(mixed mono- and dinonylphenyl) phosphite. Tri (mixed
mono-and dinonylphenyl) phosphite is particularly suitable.
Suitable triazoles include benzotriazole and
alkyl-substituted benzotriazoles having 1 or 2 alkyl
groups containing 1 to 10 carbon atoms, preferably 1
carbon atom. Benzotriazole is available under the trade
name Cobratec 99 from Sherwin-Williams Chemical. A partic-
ularly suitable alkyl-substituted triazole iq tolyltriazole
which is available under the trade name Cobratec TT-100
from Sherwin-Williams Chemical.
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7~'7'7
Suitable partial esters of an alkyl or alkenyl-
succinic anhydride are the products obtained by the
reaction of one molar equivalent of a polyhydric alcohol
with two molar equivalents of the anhydride. Structurally,
these materials are represented by the formula
C(O)OH f (o) OH
R-f-H H-f-R
. R'-f-H H-C~R"
C-(O)OR"- O(O)C n
wherein of the radicals R and R' one is hydrogen and the
other is an alkyl or alkenyl group containing from 8 to 15
carbon atoms and R" is the residue of the polyhydric
alcohol which generically may contain oxygen, sulfur, or
- nitrogen in the chain as well as ester substituents, and
preferably contains from 3 to 6 carbon atoms. The integer
n represents a number from 1 to 4. In so doing, n include ,
in the residue, derivatives of diols, triols, and other
polyhydroxy compounds.
A preferred partial ester for use in our invention
,~ 20 is represented by the formula
~- O O
, 11 11
f-OH f-OH
R-C-H H-C-R
,.,,. l l
R'-f-H H-F-R'
25ICl OR"O-C
wherein of R and R', one represents hydrogen and the other
, a branched chain dodecenyl group and R" iS an alkylene
group of 3 to 6 carbon atoms.
A commercially available partial ester which can
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~1474~7`7
- be used in our invention is "Hitec" E536*, available from
Edwin Cooper Company, St. Louis, Missouri.
The preparation of and additional information
concerning these partial esters are provided by U.S. Patent
No. 3,117,901.
Tricresyl phosphate is a well known chemical, being
represented by the formula (C6H4Me)P04. Any high quality,
commercially available tricresyl phosphate can be used.
Diphenylamine or alkylated diphenylamines containing
10 1 or 2 alkyl groups containing about 4 to about 16 carbon atoms
per group can be used in the compositions of our invention. The
latter-named material is preferred. A suitable commercially
available alkylated diphenylamine is "~augalube" 438-L*,
available from the Chemical Division of UNIROYAL. This material
is predominantly P,P'-dinonyldiphenylamine. It has the following
physical properties: Specific Gravity -- 0.99; Flash Point
; -- 350-F: Viscosity, 100-F, SUS -- 3900; Viscosity -- 210-F
-- 86 SUS.
Phenyl a-naphthylamine and phenyl ~-naphthylamine
are suitable for use in our invention. Preferred materials of
this type are phenyl a-naphthylamine, or phenyl ~-naphthylamine,
having 1 or 2 alkyl or alkaryl substituents, each of which
contains 1 to about 16, preferably about 6 to about 8,
carbon atoms. A suitable commercially available material of
the latter type is ~Naugalube~ 460-C*, available from the
Chemical Division of UNIROYAL. This material is a mixture of
a major amount of di-styrenated phenylbetanaphthylamine and a
minor amount of mono-styrenated phenylbetanaphthylamine. It
* Trade M æks
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~V~ 77
has the following typical properties: Specific Gravity --
1.05; Percent Ash -- C0.1; Percent Nitrogen -- 2.8-2.9.
The vinyl-pyrrolidone--a-olefin copolymers which
are suitable for use in our invention are characterized as
being the reaction product of N-vinyl-2-pyrrolidone and 0.5
to 12 moles of an a-olefin containing 8 to 30 carbon atoms,
preferably 18 to 22 carbon atoms. The materials have a
,
molecular weight of about 2,000 to about 20,000, preferably
7,000 to 12,000. Details on the preparation and properties
of the copolymers are provided in U.S. Patent Nos. 3,296,134
and 3,423,3~1. The preferred copolymer is the reaction product
of 1 mole of N-vinyl-2-pyrrolidone and 1 mole of a C-20
a-olefin. An example of a commercially available preferred
copolymer is "Ganex" V-220*, which is available from GAF
Corporation, 140 West 51st Street, New York, New York. This
material has the following physical properties:
,
i';
Physical Form, 25-C waxy solid
'~ Relative Viscosity (1) 1.007
Density (2) o.gs
20 Average Molecular Weight (3) 8,600
- Softening Point 30C
Melting Range (4) 32-36-C
(1) 0.1 g/100 ml toluene used as solvent
' (2) gm/cc @ 23C
(3) Molecular weight number average determined by
High Speed Osmometer in toluene at 25C
*Trade Mark
, . ,
- ~047~77
(4) Determined on the Mannheim Block
; Amounts of Materials Used
The amounts of the various materials used in the
turbine oil compositions of our invention are shown below,
in both suitable and preferred ranges.
Amount
(Weight Percent)
Material Suitable ~Prefe~-ed
Phosphite 0.05-1.5 0.10~1.0
Diphenylamine
(or alkylated diphenylamine) 0.02-0.75 0.05-0.50
Phenyl-naphthylamine0.10-0.75 0.15-0.35
Triazole 0.002-0.10 0.005-0.030
Partial Ester of Alkyl
or Alkenyl Succinic Anhydride 0.02-0.50 0.05-0.10
Copolymer of N-vinyl-
2-pyrrolidone and -olefin0.05-1.500.10-0.80
As is implied, the balance of the composition is -
the base lubricating oil, it being understood that other
; 20 conventional lubricant additives can be included, if
desired.
Use of Other Materials in Our Invention
In describing our invention, we have shown only
the essential materials which are used therein. It is to
be understood that other conventional lubricating oil
additives can be used in the composition, if desired.
Examples of other such materials include, but are not
limited to, antifoam agents, pour point depreRsants,
viscosity and viscosity index improvers, and dyes.
In order to disclose the nature of the present
invention still more clearly, the following examples, both
illustrative and comparative, will be given. It is to be
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~047477
understood that the invention is not to be limited to the
specific conditions or details set forth in these examples
except insofar as such limitations are specified in the
appended claims.
Test Methods
,,,
The test methods used to evaluate the various
compositions, both illustrative and comparative, were the
following:
~- (1) Federal Test Method 5308.6 of Standard 791 b.
(2) Rotary Bomb Oxidation Test ASTM-D-2272
, (3) ASTM-D-943 Oxidation Test
(4) Heat Stability Test
Inasmuch as the first of these tests are standard,
published tests, it is not believed necessary that they be
described herein.
Since the data from the Federal Test Method
5308.6 was used more consistently, this test will be
:--
~ described in some detail. Usually in this test, the only
- values obtained are oil viscosity change, acid number
change, and the weight loss of the metal test specimens.
In addition to these values, we obtained the amount of
solids deposited or formed during the test. This value is
expressed as milligrams of solids per 100 grams of oil
sample. In our opinion, this value is a good indicator of
the tendency to cause residues in operation of a turbine,
which, in turn, can impair performance.
A description of Federal Test Method 5308.6
follows:
A 100-ml test sample, on which viscosity in
centistokes at 100F and neutralization number have been
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1047~'77
measured, is subjected to a temperature of 347F for a
period of 72 hours in the presence of 5 liters of air per
hour and polished, cleaned, weighed copper, silver, steel,
. . .
magnesium, and aluminum coupons held rigidly in a specific
arrangement.
The test apparatus consists of a test tube (to
contain the test sample) which is fitted with vertical
water-cooled condenser and air-delivery tube extending to
within 1/8" of the bottom of the test tube. The tube is
~ 10 submerged its entire length except for the joint and
?. . condenser in a constant temperature bath at test tem-
:
perature.
, At the end of the test period specified, these
observations and measurements are made and recorded:
- 15 (a) Condenser deposits (liquid or solid) appearance.
(b) Viscosity change, % viscosity change from original at
100F, centistokes and neutralization number change
from original are determined on filtered oil.
(c) Deposits or solids contained in oil sample, in test
cell, and on coupons are collected on a filter paper
and their weight determined to the nearest 0.1 mg.
(d) Metal coupons are washed and weighed to establish
loss or gain to the nearest 0.1 mg.
(e) Deposits adhering to test cell after scraping and
; 25 washing are rated for appearance in vapor, oil-air
interface, and bottom of test cell.
A heat stability test was used to measure Cu-Pb
bearing corrosion. Briefly, this test can be described as
follows:
A copper-lead faced steel coupon, 1 x 3", is
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iO47477
cleaned in accordance with the established procedure and
weighed. Two hundred milliliters of test sample is placed
` in a 400-ml tall form beaker. The test coupon is placed in
the beaker, which is then covered with a watch glass, and
placed in a 250F oven for 96 hours. At the end of the
specified period of time the beaker is removed and allowed
to cool. The coupon is removed, washed with hexane, dried,
and weighed.
- In the following examples the materials used were
as follows. Base oils "X" and "Y" were mineral lubricating
oils. Also, both base oils were pale oils. Base oil "X"
had a viscosity of lO0 SSU at 100F, while ba~e oil "Y"
had a viscosity of 170 SSU at 100F.
- The materials, other than base oils, used in the
compositions tested were as follows:
Triazole "Cobratec" - 50-I
Phosphite Triphenyl Phosphite
Partial Ester "Hitec" - E-536
Antifoam Agent Commercially availabl,e silicone
Alkylated diphenyl amine "Naugalube" 438-L
Phenyl-~-naphthylamine "Naugalube" 460-C
Copolymer "Ganex" - V-220 ~
The amounts of the various materials used in the
compositions tested, stated in weight percent, were as
follows:
~ t~l ~ rKs
:
` ~047477
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.. o ,, o ~ o ~ ,, o ~
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m m
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--14--
- lV4~77
The results of the tests on Compositions A-E are
. shown in Table I following while the test results on
Compositions F-I are shown in Table II. For purposes of
comparison, the results of tests on a commercial high
temperature oil (understood as suitable for use in gas
,. turbines) and a typical steam turbine oil are provided in
Table III.
... .
. ~ .
:` .
'
1047~ ~ 7
:,
~, O ~ o~ . ~r o ~ . . ~ .~ ~ ~ o
U~ Ot~l-l + + + + + I +
. ~"
,
r~ N ~ ~ N O ~ ~ ~ ~ O
N IJ ) ~ a~ O U~
. . ~ ~ ~ . . N N ~ ~
O IJ ) ~ O N N + + + + + +
:
,'
Z
H ~ O ~1 O O O ~ 1~ Il' 11
O ~ N O ~ l + + + + + N
:
~ ~r N o~ ~ 0 N co ~ ~ ~ 0 0 n
'm~ m l U~ O ~ O +O O+ + O O ~j N
., ~ .'
,.,~
a~ D N ~ _I ~ N ~ ~0 ~
'7 + :'
'
R~ ~ ~ n
V . .,~ ' o ~ tl) ~ ~ V
--16--
1047~77
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`",: ~ ,,~, o . ,,~ ~ ,~ .. . . ~ F: N
.. H ~ D r--l o ,~ ~ + + ~--I o
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,.,
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o u~ O ~ ~ + + +o o+ +
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U~ ~ ~ r~ OOD~ o~ r, o
... ~ er . O O O ,1 0 1 I
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c~ zO zO 0~ m s _I tn
u ~ o
H i~ ~ 1 3 0
--17--
~o47~77
,_~ . O O u'l r~ N 11
,a ~ ~ ox 1` .. .... .
I In _l O ~1 0 0
_~ Co
~¢ O
~ ~ I +
o .,1 ~
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a~ ~u U
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3 ~ z 0
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v, o~ooJ~ ~u e :~ ~ù
,, ,~ e ~ ~ O
s~ ~q a) ~ ~ u ~ rl O
a) ,~D O O O Sl
o ~1 ~ z
~ ~ e ,~ ~ u
ra ~ xo ~ U~ ~ O ~ Q. a) ~ ~
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u ~ o ~ z u a ~ o- o
3 E~ ~u~ ~2
--18--
7~'7
.,
. A comparison of the test results on Compositions
; A-H with the test results on the commercial oils shows that
the latter are inferior to Compositions A-H. Of Composi-
tions A-H, Composition G is considered to have the best
overall properties. A comparison of the test results on
,- Composition I, which contains additionally the copolymer,
with Composition G shows that Composition I provides better
: corrosion results, better viscosity results, and better
neutralization number results. It follows that Composition
, 10 I gives better test results than the commercial oils. The
, data supports this statement.
, Thus, having described the invention in detail,
it will be understood by those skilled in the art that
., certain variations and modifications may be made without
departing from the spirit and scope of the invention as
defined herein and in the appended claims.
We claim:
~ .
.
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