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EP 0 351 906 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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16.09.1992 Bulletin 1992/38 |
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Date of filing: 11.07.1989 |
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International Patent Classification (IPC)5: C10M 169/04 // (C10M169/04, 105:36, 129:72, 133:12, 133:44, 135:02, 135:36, 137:04, 137:08, 137:10),
C10N40:00, C10N40:28 |
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Synthetic lubricant composition
Synthetische Schmierölzusammensetzung
Composition lubrifiante synthétique
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Designated Contracting States: |
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DE GB |
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Priority: |
22.07.1988 US 223128
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Date of publication of application: |
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24.01.1990 Bulletin 1990/04 |
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Proprietor: AKZO N.V. |
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NL-6824 BM Arnhem (NL) |
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Inventors: |
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- Anzenberger,Joseph Francis, Sr.
Delmont
Pennsylvania 15626 (US)
- Jung, Alfred Karl
Millwood
New York 10546 (US)
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Representative: Schalkwijk, Pieter Cornelis, c.s. et al |
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AKZO Patent Department (Dept. APTA)
Velperweg 76
P.O. Box 9300 6800 SB Arnhem 6800 SB Arnhem (NL) |
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References cited: :
EP-A- 0 144 922 FR-A- 1 119 412 FR-A- 2 206 376 US-A- 4 111 821
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EP-A- 0 195 109 FR-A- 2 102 272 US-A- 4 087 386 US-A- 4 589 990
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The present invention relates to synthetic lubricant compositions for use in high
temperature rotary engines using internally lubricated fuel, wherein the lubricant
is consumed and combusted during operation.
[0002] A wide variety of synthetic lubricants have been described in the patent and scientific
literature.
[0003] Alkyl trimellitate compositions suitable for use in lubricants and hydraulic fluids
are described in Ger. Offen. 2,14O,683, abstracted in Chemical Abstracts, Vol 76,
115812c (1972). Of similar teaching is U.S.S.R. Patent No. 525,663, abstracted in
Chemical Abstracts, Vol. 86, 92985b (1977). Blends of penta-erythritol and trimellitate
esters as a synthetic lubricating oil base stock for jet engines is described in British
Patent No. 1,481,27O.
[0004] U.S. Patent No. 3,637,5O1 describes complex esters made by reaction of a mixture
of neopentyl-type polyol, an aromatic polycarboxylic acid, and an aliphatic monocarboxylic
acid. It is suitable for lubricating gas turbine engines.
[0005] Certain dialkyl diesters of mixtures of isophthalic acid and terephthalic acid are
characterized as excellent synthetic oils in U.S. Patent No. 2,936,32O.
[0006] U.S. Patent No. 3,O21,357 describes novel dialkyl esters of 5-t-alkylisophthalic
acid which are suitable as synthetic liquid lubricants and plasticizers for synthetic
polymeric resins. A gas turbine lubricant employing, as a base stock, a blend of a
carboxylate ester (e.g., an ester of phthalic and/or isophthalic acid) and a low viscosity
mineral oil is described in U.S. Patent No. 3,912,64O.
[0007] One example of a synthetic lubricant which was tried in gas-fired rotary engines,
for example, was a product sold under the trademark STAUFFER SDL-1. It comprised about
88% of a blend of certain reaction products of trimethylolpropane with various C7-C18
carboxylic acids. It, however, produced wear and deposit problems in such engines.
[0008] British Patent No. 1,44O,129 describes lubricants containing 85-96% triisodecyl trimellitate
as a base fluid. Tricresyl phosphate is used in the lubricant of Example 2. In its
two exemplified lubricants, inorganic, metal-containing additives are also used. The
use of such metal-containing additives would give rise to an undesired ash residue
when used under high temperature conditions, e.g., those existing in gas-fired rotary
engines, above the decomposition temperature of the lubricant. Such residues lead
to wear, deposits, and other problems. Also, the lubricant shown in Example 2 of British
Patent No. 1,44O,129, although containing triisodecyl trimellitate (85%) and tricresyl
phosphate (1.5%), additionally contains an alkyl methacrylate copolymer as a viscosity
improver. Use of such a copolymer in a lubricant which is consumed during the ignition
cycles of the engine with the fuel will also lead to undesired carbon deposits. Thus,
the lubricant compositions shown in British Patent No. 1,44O,129, if used in gas-fired
rotary engines where the lubricant is sprayed into the combustion chamber for eventual
consumption along with the fuel, will lead to residue problems (e.g., ash deposition
or ash and carbon deposition).
[0009] The present lubricant composition is an improved lubricant for such engines, for
example, which is consumed with the fuel and leaves essentially no residue in the
combustion chamber. It comprises nonmetal containing constituents and is therefore
an ashless product when subjected to high temperature conditions above the decomposition
temperature of the lubricant. It does not contain polymeric additives in its additives
package which, when incinerated, would also give rise to carbon deposits.
[0010] The present engine lubricant is a blend of a major amount of at least one aromatic
tricarboxylic ester, a minor amount of antiwear agents comprising a phosphate ester,
and a minor amount of an organic additives package, which is substantially free of
metallic moieties or components and polymeric components as a result of which said
organic additives package leaves no residue in the engine when the lubricant is incinerated
during operation of the engine.
[0011] The first component for the lubricant of the present invention, which is present
in major or predominate amount and functions as the base lubricating fluid is at least
one aromatic tricarboxylic ester. A preferred triester component is a trimellitate
ester component. These esters are aromatic or benzene tricarboxylic acid triesters
having the formula Ar[C(O)OR]3, where Ar is a phenyl ring and R is an aryl or an alkyl
group, e.g., one having less than about 18 carbon atoms. Preferred alkyl groups in
such esters range from about 4 to about 18 carbon atoms in length. This component
is present at from about 75 to about 99 percent by weight of the lubricant of the
present invention.
[0012] The Table listed below gives a representative listing of potential "R" groups (i.e.,
R′, R˝ and R‴) for preferred trimellitate esters which can be used.
[0013] Preferred triesters are triisodecyl trimellitate and tris-(2-ethylhexyl)trimellitate
or their mixtures at ratios providing a desired viscosity.
[0014] An optional, component of the present invention, which can also be present in minor
amount, e.g., up to about 15 percent by weight of the lubricant, is at least one thermally
and oxidatively stable phthalate ester component. This component is used to adjust
the viscosity of the lubricant since the tri-carboxylic triesters tend to be viscous
and might not have the desired viscosity characteristics if used without this optional
phthalate ester also being present. Such a component is a benzene carboxylic acid
diester of the formula Ar(C(O)OR)2, where Ar is a phenyl ring and R is as defined
above and is an alkyl group of less than about 18 carbon atoms, e.g., from about 4
to about 1O carbon atoms. The esters that form this component can be derivatives of
such benzene dicarboxylic acids as phthalic acid, isophthalic acid and terephthalic
acid. Phthalate ester, where the substituents are in the ortho-position is not thermally
and oxidatively stable within the purview of the present invention.
[0015] Both of the above-mentioned types of tricarboxylic triesters and phthalate esters
should be substantially fully esterified so there is no appreciable unreacted acid
functionality in the ester component. Preferably, both are branch-chain aliphatic
esters of the benzene carboxylic type with suitable branch chain groups including
2-ethylhexyl, 2-ethylbutyl, isooctyl, iso-propyl, and isodecyl. Branch chain groups
derived from "Oxo" alcohols are also useful, as described in U.S. Patent No. 2,76O,934.
[0016] The second component of the present invention is a phosphate ester component at from
about O.5% to about 1O% by weight. This component is present as an antiwear and extreme
pressure additive. Preferably, the phosphate ester is one containing three aryl groups
in the form of aryl and/or alkaryl groups. Examples of useful phosphate esters are
tertiary butylphenyl/ phenylphosphate, secondary butylphenyl/phenylphosphate, and
isopropylphenyl/phenylphosphate. These phosphate esters may be prepared in accordance
with known alkylation and phosphorylation procedures as described, for example, in
U.S. Reissue Patent No. 29,54O. Mixed tertiary butyl/phenyl phosphates (primarily
di-(tert-butylphenyl) monophenylphosphate and mono-(tert-butyl)phenyldiphenylphosphate)
are highly preferred because of their availability and thermostability.
[0017] The second antiwear component of the present lubricant compositions preferable also
comprises supplemental extreme pressure antiwear agents. Suitable extreme pressure
antiwear agents include oil-soluble organosulfur compounds, in particular, sulfurized
hydrocarbons of desired molecular weight. These sulfur compounds may contain other
groups which are beneficial and include phosphoros atoms. A preferred class of organosulfur
compounds is constituted by sulfurized olefins prepared by the reaction of a C3-C6
olefin or a polyolefin derived therefrom, with a sulfur-containing compound, such
as sulfur, sulfur monochloride and phosphorpentasulfide. Such extreme pressure additives
are commercially available, frequently contained in additive packages designed for
gear lubricants. Such commercial additives may directly be used in the present invention
provided that no metal-containing components are present. Sulfurized and phosphorized
extreme pressure agents are preferred.
[0018] The third essential component of the present invention is a substantially residue-free
additives package which can comprise the following types of components:
- Load Carrying Additive
- up to 2.O, pref. O.1 to 1.O wt.%
- Corrosion Inhibitor
- O.O15 to 2.O, pref. O.1O to O.3 wt.%
- Antioxidant
- O.O5 to 2.O, pref. O.25 to 1.O wt.%
- Metal Passivator
- O.OO2 to O.5O, pref. O.O1 to O.O4 wt.%
- Wetting Agent
- up to O.2O, pref. up to O.1 wt.%
[0019] In order to be substantially residue-free, in accordance with the present invention
when the lubricant is combusted, the components used in the additives package need
to be substantially free of metallic moieties or components if ash residues are to
be avoided. In other words, they are organic, rather than either metalloorganic or
inorganic, in nature. Also, the organic additives chosen should not be polymers which,
upon incineration, give rise to carbon deposits. With these provisos in mind, representative
additives can be selected to the non-metal-containing and non-polymeric organic materials
listed as additives in British Patent No. 1,44O,129 at page 3, line 35 and following,
in accordance with the description provided herein.
[0020] The additives package used in the instant lubricant is intended to provide oxidation
stability, to enhance load carrying properties, and to prevent corrosion by chemical
attack on ferrous surfaces as well as to passivate non-ferrous metals such as copper-containing
alloys.
[0021] The useful load carrying additives include the amine salt of phosphoric and phosphonic
acid derivatives. Moreover, certain phosphorus-amine compounds will also function
as ashless antiwear additives in the synthetic base stocks of the instant invention.
Such phosphorus-amine products will also give anti rust protection. Lubricant compositions
containing the optional extreme pressure antiwear agent do not require the addition
of a load carrying additive.
[0022] There will essentially be no need for using detergent and dispersant-type additives
in the instant lubricant compositions when used in its preferred embodiment in a natural
gas-fired rotary engine. This is because the lubricant in this type of rotary engine
in not cycled and the lubricant is consumed with the fuel. Likewise, there is no need
to add a viscosity index improver to these lubricants. In particular, the type of
polymeric viscosity improvers used in British Patent No. 1,44O,129 should be avoided.
[0023] Aromatic amines have been used for many years to improve the oxidation stability
of various synthetic lubricant base stocks. Polyol esters of the type used in aircraft
gas turbine engines have a long history of using aromatic amines, such as octylphenylnaphthylamine,
phenothiazene, and phenyl-
alpha-naphthylamine to enhance the oxidation stability of such fluids.
[0024] Triarylphosphate esters are good antiwear additives under normal loading conditions
in both mineral oil-based and synthetic lubricants. For example, tert-butylphenyl/diphenyl
phosphate has the added ability to also give extreme pressure protection under more
severe loading conditions.
[0025] The following Examples illustrate certain preferred embodiments of the present invention.
Example 1
[0026] A lubricant composition in accordance with this invention is formed by admixture
of the following ingredients:
[0027] The resulting composition was an amber colored liquid, having an "oily" odor, with
an acid number of O.68 mg KOH/g. It had a boiling point of over 6OO°F (315°C), a specific
gravity of O.98 at 6O°F (15.6°C), a flash point of over 46O°F (24O°C) and a vapor
pressure of under 1.O mm Hg at 25°C. All of the ingredients mentioned above are non-metal
containing thereby rendering the entire composition an ashless, high-temperature lubricant.
Example 2
[0028]
Example 3
[0029]
Example 4
[0030]
Example 5
[0031]
Example 6
[0032]
Example 7
[0034] The foregoing Examples illustrate certain preferred embodiments of the present invention,
but should not be construed in a limiting sense. The scope of the protection that
is sought set forth in the claims which follow.
1. An engine lubricant composition which comprises a predominate amount of at least
one aromatic tricarboxylic ester, a minor amount of an antiwear agent comprising a
phosphate ester, and a minor amount of an organic additives package which is substantially
free of metallic moieties or components and polymeric components as a result of which
said organic additives package leaves no residue in the engine when the lubricant
is incinerated during operation of the engine.
2. A composition as claimed in Claim 1, wherein the tricarboxylic ester is present
at from 75 to 99%, by weight of the lubricant.
3. A composition as claimed in Claim 1 or 2, wherein the tricarboxylic ester is a
trimellitate ester having alkyl groups of from 4 to 18 carbon atoms in length.
4. A composition as claimed in any or more of Claims 1-3, wherein the antiwear agent
is present at from O.5% to 1O%, by weight of the lubricant.
5. A composition as claimed in any or more of Claims 1-4, wherein the phosphate ester
contains three aryl groups.
6. A composition as claimed in any or more of Claims 1-5, wherein the antiwear agent
further comprises a supplemental extreme pressure antiwear agent.
7. A composition as claimed in any or more of Claims 1-6, wherein the extreme pressure
antiwear agent is present at from O.25 to 5.0%, by weight of the lubricant.
8. A composition as claimed in Claims 6 or 7, wherein the extreme pressure antiwear
agent is a sulfurized synthetic product.
9. A composition as claimed in any or more of Claims 1-8 wherein the organic additives
package is present at from O.1 to 5% by weight of the lubricant.
1O. A composition as claimed in any or more of Claims 1-9 wherein the organic additives
package comprises up to 2.O% of a load carrying additive, O.O15 to 2.O% of a corrosion
inhibitor, O.O5 to 2O% of an antioxidant, O.OO2 to O.5O% of a metal passivator, and
up to O.2O% of a wetting agent, by weight of the lubricant.
11. A composition as claimed in any or more of Claims 1-1O which further comprises
a minor amount of a thermally and oxidatively stable phthalate ester.
12. A composition as claimed in Claim 11, wherein the phthalate ester is present at
up to 15%, by weight of the lubricant.
13. A composition as claimed in Claim 11 or 12, wherein phthalate ester is selected
from the group consisting of esters of isophthalic acid and esters of terephthalic
acid.
14. Use of an engine lubricant composition as claimed in any of the Claims 1-13 for
lubricating high temperature rotary engines by feeding the engine lubricant to the
combustion chamber of the engine together with fuel and consuming the lubricant during
operation of the engine.
1. Maschinenschmiermittel, das einen überwiegenden Anteil an mindestens einem aromatischen
Tricarbonsäureester, einen geringeren Anteil eines Phosphatester enthaltenden Antiabnützungsmittels
sowie einen geringeren Anteil eines organischen Additivpakets enthält, welches im
wesentlichen frei von metallischen Anteilen oder Komponenten sowie von polymeren Komponenten
ist, derart, dass das organische Additivpaket bei Verbrennung des Schmiermittels in
der laufenden Maschine keine Rückstände hinterlässt.
2. Mittel nach Anspruch 1, bei welchem der Tricarbonsäureester in einem Anteil von 75
bis 99% des Gewichts des Schmiermittels vorhanden ist.
3. Mittel nach Anspruch 1 oder 2, bei dem der Tricarbonsäureester ein Trimellithsäurester
mit Alkylgruppen ist, die eine Länge von 4 bis 18 Kohlenstoffatomen haben.
4. Mittel nach einem oder mehreren der Ansprüche 1 bis 3, in welchem das Antiabnützungsmittel
in einem Anteil entsprechend 0.5 bis 10% des Gewichts des Schmiermittels vorhanden
ist.
5. Mittel nach einem oder mehreren der Ansprüche 1 bis 4, in welchem der Phosphatester
drei Arylgruppen enthält.
6. Mittel nach einem oder mehreren der Ansprüche 1 bis 5, in welchem das Antiabnützungsmittel
ausserdem ein zusätzliches Extremdruck-Antiabnützungsmittel enthält.
7. Mittel nach einem oder mehreren der Ansprüche 1 bis 6, in welchem das Extremdruck-Antiabnützungsmittel
0.25 bis 5.0% des Gewichtes des Schmiermittels ausmacht.
8. Mittel nach einem der Ansprüche 6 oder 7, in welchem das Extremdruck-Antiabnützungsmittel
ein sulfuriertes Syntheseprodukt ist.
9. Mittel nach einem oder mehreren der Ansprüche 1 - 8, in welchem das organische Additivpaket
in einem Anteil entsprechend 0.1 bis 5 % des Gewichts des Schmiermittels vorhanden
ist.
10. Mittel nach einem oder mehreren der Ansprüche 1-9, in welchem das organische Additivpaket
bis 2.0% eines belastbaren Additivs, 0.015 bis 2.0% eines Korrosionsinhibitors, 0.05
bis 20% eines Antioxydationsmittels, 0.002 bis 0.50% eines Metallpassivierungsmittels
und bis zu 0.20% eines Netzmittels, bezogen auf das Gewicht des Schmiermittels, enthält.
11. Mittel nach einem oder mehreren der Ansprüche 1-10, das ausserdem einen geringen Anteil
eines thermisch und oxydativ stabilen Phthalatesters enthält.
12. Mittel nach Anspruch 11, in welchem der Phthalatester in einem Anteil von bis zu 15%,
bezogen auf das Gewicht des Schmiermittels, vorhanden ist.
13. Mittel nach Anspruch 11 oder 12, in welchem der Phthalatester aus der Gruppe der Isophthalsäureester
und Terephtalsäureester gewählt ist.
14. Verwendung eines Maschinenschmiermittels gemäss einem der Ansprüche 1 - 13 zum Schmieren
von Hochtemperatur-Rotationsmaschinen durch Einspeisen des Maschinenschmiermittels
zusammen mit dem Brennstoff in die Verbrennungskammer der Maschine und Verbrauch des
Schmiermittels während des Betriebs der Maschine.
1.- Une composition lubrifiante pour moteur qui comprend une quantité majeure d'au
moins un ester tricarboxylique aromatique, une quantité mineure d'un agent anti-usure
comprenant un ester phosphaté, et une quantité mineure d'un ensemble d'additifs organiques
qui est sensiblement exempt de parties ou composants métalliques et de composants
polymères, de sorte que ledit ensemble d'additifs organiques ne laisse aucun résidu
dans le moteur lorsque le lubrifiant est brûlé au cours du fonctionnement du moteur.
2.- Une composition telle que revendiquée dans la revendication 1, dans laquelle l'ester
tricarboxylique est présent en une proportion comprise entre 75 et 99%, en poids du
poids de lubrifiant.
3.- Une composition telle que revendiquée dans la revendication 1 ou dans la revendication
2, dans laquelle l'ester tricarboxylique est un ester d'acide trimellitique présentant
des groupes alkyles comprenant de 4 à 18 atomes de carbone sur leur longueur.
4.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des revendications
1 à 3, dans laquelle l'agent anti-usure est présent en quantité comprise entre 0,5
et 10% en poids du poids de lubrifiant.
5.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des revendications
1 à 4, dans laquelle l'ester phosphaté contient trois groupes aryles.
6.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des revendications
1 à 5, dans laquelle l'agent anti-usure comprend de plus un agent anti-usure de pression
extrême supplémentaire.
7.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des revendications
1 à 6, dans laquelle l'agent anti-usure sous pression extrême est présent en une quantité
de l'ordre de 0,25 à 5% du poids de lubrifiant.
8.- Une composition telle que revendiquée dans les revendications 6 ou 7, dans laquelle
l'agent anti-usure de pression extrême est un produit synthétique soufré.
9.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des revendications
1 à 8, dans laquelle l'ensemble d'additifs organiques est présent en une quantité
de l'ordre de 0,1 à 5% du poids de lubrifiant.
10.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des
revendications 1 à 9, dans laquelle l'ensemble d'additifs organiques comprend jusqu'à
2,0% d'un additif porteur de charge, de 0,015 à 2,0% d'un inhibiteur de corrosion,
de 0,05 à 20% d'un anti-oxydant, de 0,002 à 0,50% d'un agent passivateur de métal,
et jusqu'à 0,20% d'un agent mouillant en poids du poids de lubrifiant.
11.- Une composition telle que revendiquée dans l'une quelconque ou plusieurs des
revendications 1 à 10, qui comprend de plus une quantité mineure d'un ester d'acide
phtalique stable du point de vue de l'oxydation et du point de vue thermique.
12.- Une composition telle que revendiquée dans la revendication 11, dans laquelle
l'ester d'acide phtalique est présent en une quantité pouvant atteindre 15% en poids
du poids de lubrifiant.
13.- Une composition telle que revendiquée dans la revendication 11 ou la revendication
12, dans laquelle l'ester d'acide phtalique est choisi parmi le groupe consistant
en ester d'acide isophtalique et ester d'acide térephtalique.
14.- Utilisation d'une composition lubrifiante pour moteur telle que revendiquée dans
l'une quelconque des revendications 1 à 13, pour la lubrification de moteurs rotatifs
à haute température par injection du lubrifiant pour moteur dans la chambre de combustion
du moteur en même temps que le carburant et consommation du lubrifiant pendant le
fonctionnement du moteur.