Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic phosphorus compound – wherein the phosphorus is...
Reexamination Certificate
2001-08-17
2003-03-11
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic phosphorus compound, wherein the phosphorus is...
C508S429000, C508S430000, C508S437000, C508S438000, C508S440000
Reexamination Certificate
active
06531429
ABSTRACT:
The invention relates to improved compositions comprising thiophosphoric acid esters and dithiophosphoric acid esters or phosphoric acid thioesters, and to the use of those lubricant compositions in improving the performance properties of lubricants, such as greases, metal-working fluids, gear fluids and hydraulic fluids.
Additives added to the said lubricants have to fulfil demanding requirements, such as a high load-carrying capacity, protection against corrosion and wear, and antioxidation activity. Zinc dialkyldithiophosphates are suitable for that purpose but, on environmental protection grounds, attempts are being made to replace those compounds by metal-free compounds. The use of metal-free hydraulic fluids is called for especially in agriculture or generally in mobile hydraulic units, where leakages present a risk of contamination of soil or water with zinc compounds. There is therefore a need for metal-free and ashless additives. Suitable hydraulic fluids must also meet the specifications of the leading hydraulic machine manufacturers, for example Denison HFO (Denison Hydraulics) or Vickers M-2980-S (Vickers), and need to be compatible with water. In addition, in accordance with the specifications of DIN 51524 and Denison HFO, they should achieve a failure load stage (FLS) of at least 10 in the FZG test.
Known oil additives for fluids are dithiophosphoric acid esters of the type:
which are available commercially under the trademark Irgalube® 63 (trademark of Ciba Spezialitätenchemie).
U.S. Pat. Specification No. 5,531,911 describes zinc-free hydraulic fluids that comprise phosphorus- and sulfur-containing additive components. One component is a thiophosphoric acid ester of the triphenylthiophosphate type (IRGALUBE TPPT). This is combined with dithiophosphoric acid esters of the IRGALUBE 63 type and with other optional oil additive components, for example ammonium sulfonates.
A disadvantage of such formulations is their lack of compatibility with water. The contamination of a hydraulic oil with water is a frequent occurrence, especially in the case of mobile hydraulic units. The use of phosphorus- and sulfur-containing additives gives rise to hydrolytic degradation with the formation of corrosive decomposition products that may attack the metals used in the hydraulic units, e.g. steel and copper alloys, and cause damage to hydraulic pumps. In addition, agglomerations of those decomposition products may also block the filters of by-pass filtration units. Since the service life of hydraulic units can be significantly extended by means of very fine filtering, the filter pore sizes of modern by-pass filtration units have been reduced from the earlier 30 &mgr;m to the current 6 &mgr;m. Consequently, only hydraulic oils that form only extremely small amounts of hydrolytic decomposition products when contaminated with water can be used.
The problem underlying the present invention is to prepare compositions that have improved compatibility with water and a significantly lower tendency to form undesired hydrolysis products.
It has surprisingly been found that the addition of a further additive component from the group of the polyol partial esters, amines and epoxides to compositions comprising thiophosphoric acid esters combined with dithiophosphoric acid esters or phosphoric acid thioesters gives compositions that when contaminated with water have a significantly lower tendency to form corrosive hydrolysis products and exhibit very good filtration characteristics. By the addition of further oil additives, e.g. aminephosphates, the load-carrying capacity can be increased and FZG failure load stages≧10 can be achieved.
The invention relates to compositions comprising:
a) a base oil of lubricating viscosity;
b) at least one thiophosphoric acid ester of formula:
wherein R
1
, R
2
and R
3
are C
3
-C
20
hydrocarbon radicals;
c) at least one dithiophosphoric acid ester or phosphoric acid thioester of formula:
wherein X is oxygen or sulfur and R
1
, R
2
and R
3
are unsubstituted or substituted C
3
-C
20
hydrocarbon radicals; and
d) at least one oil additive from the group of the polyol partial esters, amines and epoxides.
A preferred embodiment concerns compositions comprising:
a) a base oil of lubricating viscosity used for greases, for metal-working fluids, for gear fluids or for hydraulic fluids;
b) at least one thiophosphoric acid ester of formula I wherein R
1
, R
2
and R
3
are C
3
-C
20
hydrocarbon radicals;
c) at least one dithiophosphoric acid ester of formula II wherein X is sulfur and R
1
, R
2
and R
3
are unsubstituted C
3
-C
10
hydrocarbon radicals or wherein R
1
and R
2
are unsubstituted C
3
-C
10
hydrocarbon radicals and R
3
is a substituted C
3
-C
10
hydrocarbon radical;
d) at least one oil additive from the group of the polyol partial esters, amines and epoxides;
e) an ammonium phosphate ester of formula:
wherein R
1
and R
2
are C
1
-C
20
hydrocarbon radicals and R
a
, R
b
, R
c
and R
d
are each independently of the others hydrogen or a C
1
-C
20
hydrocarbon radical; and
f) at least one customary oil additive.
An especially preferred embodiment concerns compositions in which the phosphorus content of the thiophosphoric acid ester component b) combined with the dithiophosphoric acid ester or phosphoric acid thioester component c), based on the composition comprising components a), b) and c), is less than 400 ppm.
A more especially preferred embodiment concerns compositions in which the phosphorus content of the thiophosphoric acid ester component b) combined with the dithiophosphoric acid ester or phosphoric acid thioester component c) and the ammonium phosphate ester component e), based on the total composition, is less than 400 ppm.
The compositions are especially suitable as multi-functional anti-wear additives—having an additional antioxidative activity—for lubricants, such as greases, metal-working fluids, gear fluids or hydraulic fluids. They are substantially metal-free and ashless and meet the mentioned specifications. Surprisingly, mixtures of components b) and c) in the base oil a) having phosphorus concentrations of less than 400 ppm give very good anti-wear properties, that is to say very good values in the four ball test, and very good friction wear values. With the addition of the additive component from the group of the polyol partial esters, amines and epoxides (component d)), the filtration characteristics of those mixtures when contaminated with water are very good. By adding further oil additives (component e)), failure load stages≧10 can be achieved. Such mixtures meet the hydraulic machines specifications of leading manufacturers, especially Denison HFO.
The terms and definitions used in the context of the description of the present invention preferably have the following meanings:
Component a)
A base oil of lubricating viscosity can be used for the preparation of greases, metal-working fluids, gear fluids and hydraulic fluids. Suitable greases, metal-working fluids, gear fluids and hydraulic fluids are based, for example, on mineral oils or synthetic oils or mixtures thereof. The lubricants will be familiar to the person skilled in the art and are described in the relevant specialist literature, such as, for example, in
Chemistry and Technology of Lubricants;
Mortier, R. M. and Orszulik, S. T. (Editors); 1992 Blackie and Son Ltd. for GB, VCH-Publishers N.Y. for U.S., ISBN 0-216-92921-0, see pages 208 et seq. and 269 et seq.;
in Kirk
-
Othmer Encyclopedia of Chemical Technology, Fourth Edition
1969, J. Wiley & Sons, New York, Vol. 13, page 533 et seq. (
Hydraulic Fluids
);
Performance Testing of Hydraulic Fluids
; R. Tourret and E. P. Wright, Hyden & Son Ltd. GB,
on behalf of The Institute of Petroleum London, ISBN
0 85501 317 6;
Ullmann's Encyclopedia of Ind. Chem., Fifth Completely Revised Edition,
Verlag Chemie, DE-Weinheim, VCH-Publishers for U.S., Vol. A 15, page 423 et seq. (
lubricants
),
Vol.
A 13, page 165 et seq. (
hydraulic fluids
).
The lubricants are especially oils and grease
Clark Dudley
Fletschinger Michael
Hamblin Peter Collen
Ribeaud Marc
Rohrbach Peter
Ciba Specialty Chemicals Corporation
Mansfield Kevin T.
Medley Margaret
LandOfFree
Lubricant compositions comprising thiophosphoric acid esters... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lubricant compositions comprising thiophosphoric acid esters..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lubricant compositions comprising thiophosphoric acid esters... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3028577