How to extend lubricant life

Abstract

The present invention relates to a method for extending the life of a lubricant composition, the lubricant composition comprising one or more base oils and one or more additives, at least one of the additives being a depleting additive; i. identifying an amount of one or more depleting additives required for a desired extended life of a lubricant composition, said extended life being greater than a standard life of said lubricant composition; ii. providing a first portion of the one or more exhaustible additives to a fresh lubricant composition; iii. providing the remainder of the amount of the one or more exhaustible additives in two or more portions spread over a typical life of the lubricant composition; The present invention provides a method comprising:

Description

[Technical field]

[0001] The present invention relates to a method for extending the life of a lubricant composition. [Background technology]

[0002] A lubricant composition contains a mixture of one or more base oils and one or more additives. Each lubricant composition is formulated to perform a specific function in a particular type of equipment. Much design and innovation has led to the development of lubricant compositions that maintain superior function over an extended life. However, even with tailored formulations and ideal operating conditions, lubricant compositions deteriorate over time.

[0003] At least some of this degradation is due to the depletion of certain additives within the lubricant composition. In particular, antioxidant additives are "sacrificial" or "depleting" additives because their mechanism of action involves scavenging or reacting with oxidized molecules. Other additives, such as antiwear additives, are also known to deplete or deteriorate over time.

[0004] Extending the life of a lubricant composition is a desirable goal, and much research has focused on extending the oil drain interval (ODI), which is a measure of how long a machine can function at an efficient level while lubricated with a particular lubricant composition before requiring a complete replacement of the lubricant composition.

[0005] Not all components in a lubricant composition deteriorate or deplete at the same rate. Thus, a lubricant composition may require replacement while many components in the composition are still in a usable condition. In particular, certain additives may deplete or deteriorate over time, and such depleted lubricant compositions become unsuitable for use by no longer meeting mandated standards.

[0006] Slow release additive gels have been proposed as one option to overcome this problem (e.g., in U.S. Pat. No. 6,843,916 and WO 2010014528). However, the complex techniques for producing such gels have proven difficult, and such gels are generally not suitable for large-scale devices such as turbines.

[0007] To extend the life of lubricants, filtration systems have also been proposed that physically and / or chemically remove decomposition products, such as those described in U.S. Pat. No. 5,009,799. These systems remove decomposition products, but may also remove useful compounds, especially acidic additives. Filters are also not compatible with all oil types. Summary of the Invention

[0008] Used lubricant compositions are often discarded, as reprocessing and reuse are not yet standard processing methods in the field. Efforts to extend the life and / or oil drain interval of lubricant compositions have environmental benefits, as well as increased convenience and reduced costs for the end user. Improved methods of extending the life of lubricant compositions are always desirable.

[0009] The present invention relates to a method for extending the life of a lubricant composition, the lubricant composition comprising one or more base oils and one or more additives, at least one of the additives being a depleting additive; i. identifying an amount of one or more depleting additives required for a desired extended life of a lubricant composition, said extended life being greater than a standard life of said lubricant composition; ii. providing a first portion of the one or more exhaustible additives to a fresh lubricant composition; iii. providing the remainder of the amount of the one or more exhaustible additives in two or more portions spread over a typical life of the lubricant composition; The present invention provides a method comprising: [Brief description of the drawings]

[0010] [Figure 1] The results of the examples of the present invention are shown. [Diagram 2] The results of the examples of the present invention are shown. [Diagram 3] The results of the examples of the present invention are shown. [Figure 4] The results of the examples of the present invention are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention provides a means for extending the life of a lubricant composition, the lubricant composition comprising one or more base oils and one or more additives.

[0012] The lubricant composition may be any lubricant composition suitable for lubricating a device. The device may be, for example, an internal combustion engine, an electric motor, an automatic transmission, a manual transmission and / or differential, a hydraulic system, a pump, or other mechanical device. The present invention particularly relates to lubricant compositions used in turbine oils, such as those suitable for use in steam and gas turbines and turbocompressors, and lubricant compositions for use in hydraulic systems.

[0013] The lubricant composition comprises one or more base oils.The base oil used in the present invention is not particularly limited, and various conventional known mineral oils and synthetic oils can be advantageously used.The base oil used in the present invention can advantageously comprise a mixture of one or more mineral oils and / or one or more synthetic oils.

[0014] Mineral oils include paraffinic, naphthenic, or mixed paraffinic / naphthenic liquid petroleum oils and solvent- or acid-treated mineral oil lubricating oils that may be further refined by hydrofinishing processes and / or dewaxing.

[0015] Synthetic oils include hydrocarbon oils such as olefin oligomers (PAOs), dibasic acid esters, polyol esters, and dewaxed waxy raffinates.

[0016] Fischer-Tropsch derived base oils (also called GTL base oils) may also be advantageously used as the base oil in the lubricating oil compositions of the present invention.

[0017] The lubricant composition also includes one or more additives. Suitable additives can be selected based on the intended use of the lubricant composition, the equipment to be lubricated, and the conditions under which lubrication occurs. Typical additives for use in the lubricant composition include, but are not limited to, antioxidants, antifoam agents, dispersants, viscosity modifiers, friction modifiers, detergents, pour point depressants, corrosion inhibitors, extreme pressure / antiwear additives, demulsifiers, and mixtures thereof.

[0018] The one or more additives may be provided to the lubricant composition individually or as part of a preformulated additive package. The additives and / or additive packages may be provided to the lubricant composition in diluted form, in which case the diluent may comprise additional base oil.

[0019] At least one of the above additives is a depleting additive. Such depleting additives are additives that are consumed over the life of the lubricant composition by either physical or chemical degradation. The depleting additives that are particularly relevant to the method of the present invention include antioxidant additives, antiwear additives, and rust or corrosion inhibitors. More specifically, the depleting additive in the present invention is one or more antioxidant additives.

[0020] Antioxidant additives typically used in lubricant compositions and relevant to the method of the present invention are so-called hindered phenolic or aminic antioxidants, such as naphthols, sterically hindered mono-, di-, and trihydric phenols, sterically hindered di-, tri-, and polynuclear phenols, alkylated or styrenated diphenylamines or ionol-derived hindered phenols. Particularly preferred antioxidant additives for use in the present invention include alkylated diphenylamines, hindered phenols, and alkylated phenyl α-naphthylamines.

[0021] In the method of the present invention, the amount of one or more exhaustible additives required for the desired extended life of the lubricant composition is identified. This is done by: i) identifying the standard (i.e., non-extended) life (X hours) of a lubricant composition containing the same base oil and additives to which the method of the present invention is not applied; ii) identifying the desired extended life (Y hours) of the lubricant composition, where Y is greater than X, preferably at least 1% greater than X, more preferably at least 2% greater than X, and even more preferably at least 5% greater than X; and iii) identifying the amount of said one or more exhaustible additives required to support the lubricant composition for the desired extended life. The step of identifying the standard life (X hours) can be carried out by considering known lubricant compositions, equipment, conditions, and applications. The step of identifying the desired extended life (Y hours) can be achieved by considering the practicality of the equipment and conditions, as well as the life of other components in the lubricant composition. This determination of the amount of the one or more depletable additives necessary to support the lubricating composition for the desired extended life can be made based on known degradation / depletion timescales for the one or more depletable additives in question in the type of oil, as well as for the type of use expected for the lubricating composition.

[0022] The total amount of one or more depleting additives used in the method of the present invention is preferably 1 wt% or less based on the total mass of the lubricating composition. This is particularly relevant for mineral oil turbine fluid type lubricant compositions. Preferably, the total amount of one or more depleting additives used in the method of the present invention is preferably 0.80 wt% or less, more preferably 0.75 wt% or less based on the total mass of the lubricating composition. Typically, the total amount of one or more depleting additives used in the method of the present invention is 0.001 wt% or more, preferably 0.01 wt% or more, more preferably 0.1 wt% or more based on the total mass of the lubricating composition.

[0023] One potential advantage of the present invention is that the amount of depletable additive required to support extended life may be less than the amount required for standard life.

[0024] The first portion of the amount of the one or more depletable additives is added to a fresh lubricant composition. The term "fresh" as used herein means a lubricant composition before it has been used in a machine or device. Elements of the lubricant composition may be reused or recycled, but the composition itself has not been used before.

[0025] The first part may be added to the lubricant composition during formulation, ie, while the base oil and any other additives are blended, or it may be added in situ.

[0026] The first portion of depletable additives may be in an amount ranging from 30 to 70% by weight, preferably in the range of 40 to 60% by weight of the total amount of the one or more depletable additives.

[0027] The first portion may be added either as an individual additive or as part of a mixed additive package together with other additives to form a fresh lubricant composition.

[0028] The remainder of the amount of the one or more exhausting additives is then added in two or more further portions spread over the extended life of the lubricant composition. Suitably, the remainder of the amount is in the range of 30-70 wt.%, preferably in the range of 40-60 wt.%, of the total amount of the one or more exhausting additives. This remainder is preferably divided equally between the two or more further portions. For example, if two further portions are added, each further portion will preferably contain in the range of 40-60 wt.%, more preferably about 50 wt.%, of the remaining amount of the exhausting additive. Alternatively, if three further portions are added, each further portion will preferably contain in the range of 30-35 wt.%, more preferably about 33 wt.%, of the remaining amount of the one or more exhausting additives.

[0029] The further portion may be provided as an individual additive or as an additive booster package containing a mixture of additive and diluent, such as a base oil, etc. In a preferred embodiment, the further portion is provided as an additive booster package comprising one or more antioxidant additives and one or more base oils.

[0030] The further portions are added after periods spaced over the standard lifespan. Preferably, the periods are approximately evenly spaced over the standard lifespan. For example, the periods may be determined by dividing the standard lifespan by the number of portions being added.

[0031]

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[0032] A first portion of the amount of one or more depleting additives is added to the fresh lubricant composition, i.e., at time=0 hours. Further portions may then be added, in turn, at addition times determined to be within the range of 30 hours, preferably 20 hours, before the end of each period, to 30 hours, preferably 20 hours, after the end of each period. Thus, the first further portion is added at a first addition time calculated as [0 hours+1 period]+ / -30 hours. The second further portion is added at a second addition time calculated as [first addition time+period]+ / -30 hours. The third further portion, if present, is added at a third addition time calculated as [second addition time+period]+ / -30 hours, and so on, depending on the number of further portions added.

[0033] The further portion may be added to the lubricant composition in any suitable manner. Typically, the further portion is added through an access point in the lubricated equipment, allowing mixing by the turbulence that typically occurs in lubricated equipment. However, inserts incorporated into the lubricated equipment that allow for the release of a portion over time are also envisaged. EXAMPLES

[0034] The invention will now be further described by reference to the following non-limiting examples.

[0035] Examples 1 to 6 In all six examples, the fresh lubricant composition contained a Group II mineral base oil and an additive package (total volume 360 ​​mL) that contained aminic and phenolic antioxidants and rust inhibitors, as well as other additives typical for use in turbine oils.

[0036] The typical (non-extended) life of this lubricant composition under laboratory-scale aging conditions was determined to be about 800 hours, which is a typical life according to the dry TOST oxidation stability test and is obviously not equivalent to actual oil drain intervals outside the laboratory.

[0037] An antioxidant booster package was blended. The antioxidant booster package contained the following: 30% by weight of alkylated-phenyl-alpha-naphthylamine, 20% by weight of butylated / octylated diphenylamine, 20% by weight of alkylated phenol esters, and 30% by weight of alkylated naphthalene base oil.

[0038] The lubricant compositions of the examples were maintained under conditions according to ASTM D7873: 120° C., oxygen flow rate of 3 liters / hour, in the presence of copper and steel coils. An antioxidant booster package was added to each example as follows:

[0039] Examples 1-3: Antioxidant Booster Package was added in three doses of 0.55 mL each at 192 hours, 408 hours, and 576 hours.

[0040] · Example 4: No antioxidant booster package was added to the fresh lubricant or during the test.

[0041] · Examples 5 and 6: The antioxidant booster package was added all at once (1.65 mL) to fresh lubricant at the start of the test (time = 0 hours).

[0042] During testing, samples from the examples were tested according to various tests.

[0043] ·TOST: Dry Turbine Oxidation Stability Test per ASTM D7873. Measures the insoluble by-products of the oxidation process and residual antioxidants.

[0044] RULER: Remaining Useful Life Evaluation Routine according to ASTM D6971. Measures the concentrations of phenolic and amine antioxidants separately (Remaining Antioxidant Reserve).

[0045] · MPC: Membrane Patch Colorimetric Assay per ASTM D7843. Measures insoluble oxidation by-products (varnish potential). If the value is above 40 DE the oil is considered to be at end of life.

[0046] ·RPVOT: Rotating Pressure Vessel Oxidation Stability Test per ASTM D2272. Measures the remaining oxidation life of fresh oil. If the retention is less than 25%, the oil is considered to be at the end of its life.

[0047] Six examples were tested over time using various tests at different time points, as shown in Table 1. The results of the analysis can be seen in Figures 1-4.

[0048] [Table 1]

[0049] In certain tests, the entire sample was used, therefore equivalent samples were used to demonstrate the degradation of the sample over time.

[0050] In Figure 1, the results of the RULEAR-amine only test are plotted against a) the reference oil of Example 4, b) Examples 5 and 6 where all of the antioxidant booster package was added at time 0, and c) Examples 1, 2 and 3 where the antioxidant booster package was added in portions over time. When more than one example was measured, an average is provided. Examples 1-3 were evaluated before and after the addition of the antioxidant booster package. The dotted line on this graph indicates that 25% of the amine remains, which is considered to be the "end of life" of the lubricant composition.

[0051] In Figure 2, the results of the RULER-phenol only test are plotted against a) the reference oil of Example 4, b) Examples 5 and 6 where the antioxidant booster package was added entirely at time 0, and c) Examples 1, 2 and 3 where the antioxidant booster package was added in portions over time. When more than one example was measured, averages are provided.

[0052] In Figure 3, the results of the MPC DE test are plotted for a) the reference oil of Example 4, b) Examples 5 and 6 in which the entire antioxidant booster package was added at time 0, and c) Examples 1, 2 and 3 in which the antioxidant booster package was added in portions over time. The dotted line on this graph indicates a value of 40 DE, which is considered to be the "end of life" of the lubricant composition.

[0053] In Figure 4, the results of the RPVOT test are plotted for a) the reference oil of Example 4, b) Examples 5 and 6 in which the entire antioxidant booster package was added at time 0, and c) Examples 1, 2 and 3 in which the antioxidant booster package was added in portions over time. The dotted line on this graph indicates the 25% value, which is considered to be the "end of life" of the lubricant composition.

[0054] In each test, it is clearly shown that the examples of the present invention have an extended life over the reference oil of Example 4. In comparison with Comparative Examples 5 and 6, it is clearly shown that this is not simply the result of adding additional antioxidant to the lubricant composition, but that the method of the present invention results in an extended life of the lubricant composition.

Claims

1. 1. A method for extending the life of a lubricant composition, the lubricant composition comprising one or more base oils and one or more additives, at least one of the additives being a depleting additive; i. identifying the amount of the one or more depleting additives required for a desired extended life of the lubricant composition, the extended life being greater than a standard life of the lubricant composition; ii. providing a first portion of the one or more depletable additives to fresh the lubricant composition; iii. Providing the remainder of the amount of the one or more depletable additives in two or more portions spread over the typical life of the lubricant composition; A method comprising:

2. 10. The method of claim 1, wherein the one or more depleting additives are selected from one or more of an antioxidant additive, an anti-wear additive, and an anti-rust or anti-corrosion additive.

3. 3. The method of claim 2, wherein the one or more depleting additives of the present invention are one or more antioxidant additives.

4. 10. The method of claim 1, wherein the one or more depleting additives are selected from hindered phenolic antioxidants, amine antioxidants, and mixtures thereof.

5. A method according to any one of claims 1 to 4, wherein the total amount of the one or more depleting additives used is suitably not more than 1 wt% and not less than 0.001 wt%, based on the total mass of the lubricating composition.

6. 5. The method according to any one of claims 1 to 4, wherein the first portion of the one or more depleting additives is in an amount in the range of 30 to 70 wt. %, preferably in the range of 40 to 60 wt. % of the total amount of the one or more depleting additives.

7. 7. The method of claim 6, wherein the remainder of the amount of the one or more depletable additives is provided in two further portions, each further portion containing in the range of 40 to 60 wt. %, preferably about 50 wt. %, of the remainder of the amount of the depletable additive.

8. 7. The method of claim 6, wherein the remainder of the amount of one or more depletable additives is provided in three further portions, each further portion containing in the range of 30-35 wt. %, preferably about 33 wt. %, of the remainder of the amount of depletable additive.

9. The method of any one of claims 1 to 4, wherein the further portion is provided as an additive booster package comprising one or more antioxidant additives and one or more base oils.

10. The method of any one of claims 1 to 4, wherein the periods are approximately evenly spaced over the standard lifespan.

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