JP2009532523A - Method for reducing deposit formation in lubricating oil compositions - Google Patents

Abstract

The deposit formation tendency of Group II, III and IV lubricant base oils is reduced by using a synergistic mixture of diphenylamine or phenyl-α-naphthylamine and triaryl phosphite.
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Description

  The present invention relates to a method for reducing deposit formation in a lubricating composition. More particularly, the present invention relates to a synergistic combination of antioxidants that, when added to a lubricating oil, reduces deposit formation in the lubricating oil.

  Modern lubricating oil compositions contain a major amount of oil of lubricating viscosity, and excessive performance enhancing additives (such as antioxidants, extreme pressure agents, pour point depressants, viscosity improvers, metal deactivators). Contains a small amount.

  Despite the development of numerous lubricating compositions to meet specific equipment requirements, current trends in equipment design require higher temperature, longer functioning lubricants. Higher temperatures can lead to increased oxidation of the lubricating composition, thus stimulating research for increasingly improved antioxidants.

  In Patent Document 1, a lubricating composition having improved oxidation resistance is disclosed. The lubricating oil comprises at least 2% by weight of one or more antioxidants and a dispersant or detergent. The antioxidant is selected from the group consisting of amine antioxidants, dithiophosphoric esters, phenolic antioxidants, dithiocarbonates, aromatic phosphites, and sulfurized fatty oils and olefins.

  In US Pat. No. 6,099,089, a lubricating oil stabilization composition comprising at least one diphenylamine and a neutral organic phosphate or phosphite is disclosed. Further disclosed are mixtures of amine antioxidants and certain phenolic antioxidants. The stabilizing composition is prepared by heating the antioxidant and phosphite at 40 ° C. to 150 ° C. for 0.2 to 6 hours.

  U.S. Patent No. 6,057,034 discloses a method for reducing compressor gas leakage by using a lubricating oil having at least one phosphite antioxidant and at least one second antioxidant. The second antioxidant is selected from the group consisting of amine compounds, phenolic compounds, and mixtures thereof.

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  Although oxidative stability of lubricating compositions may also be considered to result in reduced deposit formation, experience has shown that this is not always the case. Accordingly, there remains a need for lubricating oil additives that will reduce deposit formation in lubricating compositions.

  In short, the present invention is based in part on the reduction of deposit formation in Group II, III, and IV lubricant base oils where a synergistic mixture of diphenylamine or phenyl-α-naphthylamine and triaryl phosphite is used. Based on the surprising and unexpected discovery that it can be achieved through use.

  Accordingly, in one aspect of the present invention, the present invention relates to reducing deposit formation in a lubricating base oil selected from the group consisting of Groups II, III, IV, and mixtures thereof, to the base oil, diphenylamine or phenyl. Defined by adding an effective amount of a mixture of α-naphthylamine and triaryl phosphite.

  In other embodiments, a major amount of oil of lubricating viscosity selected from the group consisting of Groups II, III, IV, and mixtures thereof, and mixtures of diphenylamine or phenyl-α-naphthylamine and triaryl phosphites A lubricating oil composition comprising an effective amount of

  Suitable lubricating base oils in the practice of the present invention are any natural or synthetic oil selected from the group consisting of Groups II, III, IV, and mixtures thereof. Particularly preferred are Group III base oils, especially GTL Group III base oils.

  GTL materials can be converted into gaseous carbon-containing compounds, hydrogen-containing compounds, and / or raw material elements (hydrogen, carbon dioxide, carbon dioxide, and / or raw materials by one or more of synthesis, combination, transformation, rearrangement, and / or decomposition / disassembly processes. Carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylene, and butyne). GTL base stocks and base oils are generally lubricant viscosity GTL materials derived from hydrocarbons (eg, waxy synthetic hydrocarbons), which themselves are simpler gaseous carbon-containing compounds, hydrogen Derived from contained compounds and / or elements as raw materials. The GTL base material includes an oil that boils within the lubricating oil boiling range. This is separated / fractionated from the GTL material, eg, by distillation or thermal diffusion, and subsequently subjected to a well known contact or solvent dewaxing process to reduce / low pour point lubricating oil; Hydrolyzed oils (including hydroisomerized or isomerized dewaxed synthetic hydrocarbons); hydroisomerized or isomerized dewaxed Fischer-Tropsch (FT) materials (ie hydrocarbons, waxy hydrocarbons, waxes, And possible similar oxygenates); preferably hydroisomerized or isomerized dewaxed FT hydrocarbon, hydroisomerized or isomerized dewaxed FT wax, hydroisomerized or isomerized dewaxed synthetic wax Or a mixture thereof.

GTL substrates derived from GTL materials, in particular hydroisomerization / isomerization dewaxing FT material-derived substrates, and other hydroisomerization / isomerization dewaxing wax-derived substrates are typically dynamic. Having a viscosity (100 ° C.) of about 2 mm ² / sec to about 50 mm ² / sec, preferably about 3 mm ² / sec to about 50 mm ² / sec, more preferably about 3.5 mm ² / sec to about 30 mm ² / sec It is characterized by. This is illustrated by a GTL substrate (having a kinematic viscosity (100 ° C.) of about 4 mm ² / sec and a viscosity index of about 130 or more) derived by isomerization dewaxing of FT wax. Citation of kinematic viscosity herein refers to measurements made by ASTM method D445.

  GTL substrates and base oils derived from GTL materials, especially hydroisomerization / isomerization dewaxing FT material derived substrates, and other hydroisomerization / isomerization dewaxing wax derived substrates (wax hydroisomerization) Oil / isomerized dewaxed oil, etc.) is a base component of this invention, which further has a pour point of about −5 ° C. or lower, preferably about −10 ° C. or lower, more preferably about −15 ° C. or lower. Even more preferably, it is typically characterized by having about −20 ° C. or less. Under some conditions, it may have a convenient pour point of about −25 ° C. or less, with a useful pour point being about −30 ° C. to about −40 ° C. or less. If desired, different dewaxing steps may be performed to achieve the desired pour point. Pour point citations herein indicate measurements made by ASTM D97, and similar automated molds.

  GTL substrates derived from GTL materials, in particular hydroisomerization / isomerization dewaxing FT material-derived substrates, and other hydroisomerization / isomerization dewaxing wax-derived substrates are substrate components of this invention However, it is also typically characterized by having a viscosity index of 80 or higher, preferably 100 or higher, more preferably 120 or higher. In addition, in certain cases, the viscosity index of these substrates may preferably be 130 or greater, more preferably 135 or greater, and even more preferably 140 or greater. For example, GTL substrates derived from GTL materials, preferably FT materials, particularly FT waxes, generally have a viscosity index of 130 or higher. Citation of viscosity index herein indicates ASTM method D2270.

  In addition, GTL substrates are typically highly paraffinic (> 90% saturates) and may contain a mixture of monocycloparaffins and multicycloparaffins in combination with acyclic isoparaffins. The ratio of naphthenic (ie cycloparaffin) content in these combinations depends on the catalyst used and the temperature. Furthermore, GTL base stocks and base oils typically have very low sulfur and nitrogen contents. This generally includes less than about 10 ppm, and more typically less than about 5 ppm for each of these elements. The sulfur and nitrogen content of the GTL base stock and base oil obtained by hydroisomerization / isomerization dewaxing of FT materials, in particular FT waxes, is essentially zero.

  In a preferred embodiment, the GTL substrate comprises a paraffinic material consisting primarily of acyclic isoparaffins and only a small amount of cycloparaffins. These GTL substrates are typically greater than 60% acyclic isoparaffin, preferably greater than 80% acyclic isoparaffin, more preferably greater than 85% acyclic isoparaffin, most preferably acyclic. Contains paraffinic material consisting of more than 90% by weight of isoparaffin.

  Useful compositions of GTL substrates, hydroisomerization or isomerization dewaxing FT material-derived substrates, and wax-derived hydroisomerization / isomerization dewaxing substrates (such as wax isomerized oil / isomerized dewaxed oil) The products are listed in, for example, Patent Document 4, Patent Document 5, and Patent Document 6.

  An isomerized oil / isomerized dewaxed oil base derived from a waxy feed (which is also suitable for use in the present invention) is a paraffinic fluid of lubricating oil viscosity. This may be mineral oil, non-mineral oil, non-petroleum, or natural materials (eg gas oil, slack wax, waxy fuel hydrocracker bottom, hydrocarbon raffinate, natural wax, hydrocracked oil, pyrolysis oil, foot Or other suitable mineral oils, non-mineral oils, non-petroleum, or natural material derived waxy materials (such as one or more of the waxes from oil, coal liquefaction or shale oil) Derived from waxy feedstock, linear or branched hydrocarbyl compounds having about 20 or more carbon atoms (preferably about 30 or more), and mixtures of these isomerized / isomerized dewaxed base stocks and base oils Is done.

As used herein, the following terms have the meanings indicated below. That is,
(A) “Wax”: a hydrocarbonaceous material having a high pour point. It typically exists as a solid at room temperature (about 15 ° C to 25 ° C) and consists mainly of paraffinic material.
(B) “Paraffinic” material: any saturated hydrocarbon. Such as alkanes. Paraffinic materials may include linear alkanes, branched alkanes (isoparaffins), cycloalkanes (cycloparaffins; monocyclic and / or polycyclic), and branched cycloalkanes.
(C) “Hydrogenation”: The feedstock is heated with hydrogen under high pressure and usually in the presence of a catalyst to remove and / or convert less undesirable components to produce an improved product. It is a purification process that is manufactured.
(D) “Hydrogenation”: a catalytic hydrogenation process that converts sulfur and / or nitrogen-containing hydrocarbons to hydrocarbon products with reduced sulfur and / or nitrogen content. This produces hydrogen sulfide and / or ammonia as by-products (respectively). Similarly, oxygen-containing hydrocarbons can also be reduced to hydrocarbons and water.
(E) “Hydrodewaxing” (or catalytic dewaxing): normal paraffins (waxes) and / or waxy hydrocarbons are converted to lower molecular weight species by cracking / cleavage and more separated by rearrangement / isomerization. A contact process added to branched iso-paraffins.
(F) “Hydroisomerization” (or isomerization or isomerization dewaxing): normal paraffins (waxes) and / or slightly branched iso-paraffins that are more branched by rearrangement / isomerization. It is a contact process that is converted to paraffin.
(G) “Hydrocracking”: Hydrogenation is a catalytic process involving the cracking / cutting of hydrocarbons. For example, heavier hydrocarbons are converted to lighter hydrocarbons, or aromatic and / or cycloparaffins (naphthenes) are converted to acyclic branched paraffins.

  As indicated above, isomerized oil / isomerized dewaxed oil base suitable for use as a necessary component in the present invention can be derived from a waxy feedstock (such as slack wax).

  Slack wax is wax that is recovered from petroleum by solvent or automatic cooling dewaxing. Solvent dewaxing uses a cooled solvent such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), a mixture of MEK / MIBK, a mixture of MEK and toluene, while auto-cooling dewaxing adds an additive such as propane or butane. Pressed liquefied low boiling hydrocarbons are used.

  Slack wax secured from petroleum may include sulfur and nitrogen containing compounds. These heteroatomic compounds are removed by hydrogenation (not hydrocracking), for example by hydrodesulfurization (HDS) and hydrodenitrogenation (HDN), to give a subsequent poisoning / Inactivation must be prevented.

  In a preferred embodiment, the GTL material from which the GTL substrate is derived is an FT material (ie, hydrocarbon, waxy hydrocarbon, wax). The slurry FT synthesis process may advantageously be used to synthesize feedstock from CO and hydrogen. In particular, using an FT catalyst containing a catalytic cobalt component provides a higher alpha value for producing the more desirable higher molecular weight paraffins. This process is also well known to those skilled in the art.

In F-T synthesis process, a synthesis gas containing H ₂ and CO mixture is a hydrocarbon, preferably in contact with the liquid hydrocarbon conversion. The hydrogen / carbon monoxide molar ratio is wide and may be in the range of about 0.5-4. However, this is more typically in the range of about 0.7 to 2.75, preferably about 0.7 to 2.5. As is well known, the FT synthesis process includes a process in which the catalyst is in the form of a fixed bed, fluidized bed, or in a hydrocarbon slurry liquid as a slurry of catalyst particles. The stoichiometric molar ratio of the FT synthesis reaction is 2.0. However, there are many reasons for using other than stoichiometric ratios, as is well known to those skilled in the art. In the cobalt slurry hydrocarbon synthesis process, the H ₂ / CO feed molar ratio is typically about 2.1 / 1. A synthesis gas containing a mixture of H ₂ and CO is bubbled upwards at the bottom of the slurry and reacts in conditions effective to form hydrocarbons in the slurry liquid in the presence of particulate FT synthesis catalyst. . Part of it is liquid at reaction conditions and constitutes a hydrocarbon slurry liquid. The synthesized hydrocarbon liquid is separated from the catalyst particles as a filtrate by means such as filtration, although other separation means such as centrifugation can be used. Some of the synthesized hydrocarbons exit as vapor from the top of the hydrocarbon synthesis reactor along with unreacted synthesis gas and other gaseous reaction products. Some of these overhead hydrocarbon vapors are typically condensed to a liquid and combined with a hydrocarbon liquid filtrate. Thus, the initial boiling point of the filtrate may vary depending on whether some of the condensed hydrocarbon vapor is combined with it. The process conditions for slurry hydrocarbon synthesis vary to some extent depending on the catalyst and the desired product. Mainly _{C 5+} paraffins _(e.g., C _{5+ -C 200),} preferably the effective typically a hydrocarbon containing _{C 10+} paraffins, to form a slurry hydrocarbon synthesis process (using a catalyst comprising a supported cobalt component) Typical conditions include, for example, a temperature of about 320-850 ° F., a pressure of 80-600 psi, and a gas space velocity of 100-40,000 V / hr / V (standard volume of gaseous CO and H ₂ mixture (0 ° C., 1 Pressure) / time / volume of catalyst). The hydrocarbon synthesis reaction is preferably performed under conditions where a limited water gas shift reaction occurs or does not occur at all (more preferably no water gas shift reaction occurs during hydrocarbon synthesis). The reaction is also carried out under conditions that achieve an alpha value of at least 0.85, preferably at least 0.9, more preferably at least 0.92, so that more desirable higher molecular weight hydrocarbons are synthesized. It is preferable. This has been achieved in a slurry process using a catalyst containing a catalytic cobalt component. The person skilled in the art knows that the alpha value means the Schulz-Flory kinetic alpha value. Although suitable FT reaction type catalysts include, for example, one or more Group VIII catalyst metals (such as Fe, Ni, Co, Ru, and Re), the catalyst preferably includes a cobalt catalyst component. . In one embodiment, the catalyst comprises Co and a catalytically effective amount of one or more of Re, Ru, Fe, Ni, Th, Zr, Hf, U, Mg, and La on a suitable inorganic support material. Preferably, it is supported on one or more refractory metal oxides. A preferred support for the Co-containing catalyst in particular comprises titania. Useful catalysts and their preparation are well known and illustrative. However, non-limiting examples may be found in, for example, Patent Document 7, Patent Document 8, Patent Document 9, Patent Document 10, and Patent Document 11.

  As noted above, the waxy feedstock from which the substrate is derived is a wax or waxy feedstock from mineral oil, non-mineral oil, non-petroleum, or other natural material. In particular, slack wax or GTL material, preferably FT material (referred to as FT wax). The FT wax preferably has an initial boiling point range of 650-750 ° F. and preferably boils continuously to an endpoint of at least 1050 ° F. A narrower waxy feed may also be used during hydroisomerization. A portion of the n-paraffin waxy feed is converted to a lower boiling isoparaffinic material. Thus, there must be sufficient heavy n-paraffinic material to obtain an isoparaffin-containing isomerized oil boiling in the lube range. If catalytic dewaxing is also performed after isomerization / isomerization dewaxing, some of the isomerized oil / isomerized dewaxed oil will also be hydrogenated to lower boiling materials during conventional catalytic dewaxing. Will be broken down. Accordingly, the end point of the waxy raw material is preferably more than 1050 ° F. (1050 ° F. +).

  The waxy feed preferably comprises the entire 650-750 ° F. + fraction formed by the hydrocarbon synthesis process, with an initial cut point of 650 ° F.-750 ° F. (determined by the employee) and an end point of preferably 1050 Has over ° F. This is determined by the catalyst and process variables used by the synthesis personnel. The waxy feed may be processed as a whole fraction or as a subset of the whole fraction prepared by distillation or other separation techniques. Waxy feeds also typically contain more than 90% paraffinic hydrocarbons, generally more than 95%, preferably more than 98% by weight, most of which are normal paraffins. It has negligible amounts of sulfur and nitrogen compounds (eg less than 1 wppm each) and has less than 2,000 wppm oxygen, preferably less than 1,000 wppm, more preferably less than 500 wppm in the form of oxygenates . A waxy feed having these characteristics and useful in the process of the present invention has been made using a slurry FT process using a catalyst having a catalytic cobalt component, as previously indicated.

The process of making the lubricating oil base material from a waxy material (eg, slack wax or FT wax) may be characterized by a hydrodewaxing process. When slack waxes are used as raw materials, they are subjected to a pre-hydrogenation step under conditions already known to those skilled in the art, so that sulfur and nitrogen-containing compounds (catalyst poisoning or deactivation). May be reduced to a level that would effectively avoid or may need to be removed. This would otherwise deactivate the hydroisomerization / hydrodewaxing catalyst used in the next step. If FT wax is used, these pretreatments are not necessary. This is because, as indicated above, these waxes have a trace (less than about 10 ppm, or more typically less than about 5 ppm to zero) sulfur or nitrogen compound content. However, some hydrodewaxing catalysts fed to the FT wax may be for the removal of oxygenates, while others may be for the treatment of oxygenates. The hydrodewaxing process may be performed with a combination of catalysts or a single catalyst. The conversion temperature ranges from about 150 ° C. to about 500 ° C. at a pressure of about 500 to 20,000 kPa. This process may be operated in the presence of hydrogen, and the hydrogen partial pressure is in the range of about 600-6000 kPa. The ratio of hydrogen / hydrocarbon feedstock (hydrogen circulation rate) is typically about 10-3500 n. l. l. ^-1 (56 to 19,660 SCF / bbl), and the space velocity of the raw material is typically about 0.1 to 20 LHSV, preferably 0.1 to 10 LHSV.

  Following any necessary hydrodenitrogenation or hydrodesulfurization, the hydrotreating used to produce the substrate from these waxy feeds is an amorphous hydrocracking / hydroisomerization catalyst (lubrication). Oil hydrocracking (LHDC) catalyst, such as a catalyst comprising Co, Mo, Ni, W, Mo, etc. on an oxide support (eg, alumina, silica, silica / alumina), or crystalline hydrogenation A cracking / hydroisomerization catalyst (preferably a zeolite catalyst) may be used.

  Other isomerization catalysts and processes for hydrocracking / hydroisomerization / isomerization dewaxing of GTL materials and / or waxy materials to substrates or base oils are described, for example, in US Pat. , Patent Literature 14, Patent Literature 15, Patent Literature 16, Patent Literature 17, Patent Literature 18, Patent Literature 19, Patent Literature 20, Patent Literature 21, Patent Literature 22, Patent Literature 23, Patent Literature 24, Patent Literature 25, Patent Literature 26, Patent Literature 27, Patent Literature 28, Patent Literature 29, Patent Literature 30, Patent Literature 31, Patent Literature 4, Patent Literature 32, Patent Literature 33, Patent Literature 34, Patent Literature 35, Patent Literature 36, Patent Literature 37 , Patent Literature 38, Patent Literature 39, Patent Literature 40, Patent Literature 41, Patent Literature 42, Patent Literature 43, Patent Literature 44, Patent Literature 45, Patent Literature 46, Patent Literature 47, Patent 48, Patent Literature 49, Patent Literature 50, Patent Literature 51, Patent Literature 52, Patent Literature 53, Patent Literature 54, Patent Literature 55, Patent Literature 56, Patent Literature 57, Patent Literature 58, Patent Literature 59, Patent Document 60, Patent Document 61, and Patent Document 62. Particularly preferred processes are described in US Pat. Processes using FT wax raw materials are described in Patent Document 65, Patent Document 66, Patent Document 67, Patent Document 68, Patent Document 69, Patent Document 70, and Patent Document 71.

  A hydrocarbon conversion catalyst useful for converting the n-paraffin waxy feedstock disclosed herein to form an isoparaffinic hydrocarbon base oil is a zeolite catalyst. ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-12, ZSM-38, ZSM-48, offretite, ferrierite, zeolite beta, zeolite theta, zeolite alpha, etc. 72. These catalysts are used in combination with a Group VIII metal, in particular palladium or platinum. The Group VIII metal may be incorporated into the zeolite catalyst by conventional techniques (such as ion exchange).

  In one embodiment, the conversion of the waxy feedstock may be performed in the presence of hydrogen by a combination of Pt / zeolite beta and Pt / ZSM-23 catalyst. In other embodiments, the process for producing a lubricant base comprises hydroisomerization and dewaxing with a single catalyst (such as Pt / ZSM-35). In yet another embodiment, the waxy feed is either a single stage or a two stage, Group VIII metal filled ZSM-48, preferably Group VIII noble metal filled ZSM-48, more preferably Pt / ZSM-48. Can be supplied at. In any case, useful hydrocarbon base oil products may be obtained. Catalyst ZSM-48 is described in U.S. Patent No. 6,057,028, the disclosure of which is incorporated herein by reference in its entirety. In the isomerization dewaxing of the waxy raw material, the use of a Group VIII metal-filled ZSM-48-based catalyst is preferable because it eliminates any subsequent different dewaxing steps.

  The dewaxing step may be accomplished using any of the well-known solvents or catalytic dewaxing processes, if necessary, either the total hydroisomerized oil, or 650-750 ° F + cut, If it has not been separated from the higher boiling material prior to dewaxing, it may be dewaxed by intentionally using the existing 650-750 ° F. material. In solvent dewaxing, the hydroisomerized oil is contacted with a cooling solvent such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), MEK / MIBK mixture, or MEK / toluene mixture, and further cooled. Thus, a higher pour point material may be deposited as a waxy solid. This is then separated from the solvent-containing lubricating oil fraction which is a raffinate. The raffinate is typically further cooled with a scraping surface cooler to remove more wax solids. Low molecular weight hydrocarbons such as propane are also used for dewaxing. At that time, the hydroisomerized oil is mixed with liquid propane, at least a part of which is flushed, the hydroisomerized oil is cooled, and a wax is precipitated. The wax is separated from the raffinate by filtration, membrane separation, or centrifugation. The solvent is then stripped from the raffinate. This is then fractionated to produce the preferred substrate useful in the present invention. Catalytic dewaxing is also well known, in which the hydroisomerized oil is hydrogenated under conditions effective to lower the pour point of the hydroisomerized oil in the presence of a suitable dewaxing catalyst. Is reacted with. Catalytic dewaxing also converts a portion of the hydroisomerized oil to lower boiling materials in the boiling range, eg, 650-750 ° F. This is separated from the heavier 650-750 ° F + substrate fraction, which is fractionated into two or more substrates. Separation of the lower boiling material may be accomplished either before or during fractional distillation of the 650-750 ° F. material to the desired substrate.

Any dewaxing catalyst that will reduce the pour point of the hydroisomerized oil, preferably one that provides a lubricating oil base in large yield from the hydroisomerized oil may be used. These include shape selective molecular sieves. This has been shown to be useful for dewaxing petroleum fractions when combined with at least one catalytic metal component. This includes, for example, ferrierite, mordenite, ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-22, also known as Theta 1 or TON, and silicoaluminophosphate, also known as SAPO. . A dewaxing catalyst that has been surprisingly found to be particularly effective comprises a noble metal, preferably Pt, complexed with H-mordenite. Dewaxing may be accomplished in a fixed, fluidized, or slurry bed using a catalyst. Typical dewaxing conditions include a temperature of about 400-600 ° F., a pressure of 500-900 psig, a H ₂ process rate of 1500-3500 SCF / B (flow-through reactor), and LHSV of 0.1-10, preferably 0.2. -2.0 is included. Dewaxing typically converts 40% or less, preferably 30% or less, of hydroisomerized oil having an initial boiling point range of 650-750 ° F. to a material that boils below its initial boiling point. To be done.

GTL substrates, isomerized or isomerized dewaxed wax derived substrates have advantageous kinematic viscosities over conventional Group II and Group III substrates and base oils. This may therefore be used very advantageously with the present invention. These GTL base stocks and base oils can have substantially higher kinematic viscosities (100 ° C.) of about 20-50 mm ² / sec or less, whereas by comparison, commercial Group II base oils have kinematic viscosities (100 ° C. ) About 15 mm ² / sec or less, and commercially available Group III base oils can have a kinematic viscosity (100 ° C.) of about 10 mm ² / sec or less. Higher kinematic viscosity range GTL base stocks and base oils formulate lubricating oil compositions in combination with the present invention compared to more limited kinematic viscosity range Group II and Group III base stocks and base oils In particular, it can provide further beneficial advantages.

  In the present invention, at least one of the isomerized oil / isomerized dewaxed oil base, the GTL base, or a mixture thereof, preferably the GTL base, constitutes all or a part of the base oil. Can do.

  Preferred substrates derived from GTL materials and / or waxy raw materials are mainly characterized by having a paraffinic composition, and are further characterized by high saturation levels, low to zero sulfur, low to zero nitrogen, low It is characterized by having zero aromatics. In essence, the hue is colorless and transparent.

  One or more of isomerized oil / isomerized dewaxed oil base, GTL base, or mixtures thereof, preferably GTL base is 5 to 100% by weight of the total base oil, preferably 40 to 100% by weight, More preferably it can constitute 70-100% by weight and the amount used is left to the employee depending on the requirements of the finished lubricant.

  One or more of a hydroisomerization / isomerization dewaxed oil base, a GTL base, or a mixture thereof, preferably a GTL base (which achieves an unexpected improvement in both initial and long term metal corrosion resistance Base oils) can include natural oils as well as other synthetic and non-conventional oils, and mixtures thereof.

  Natural oils, other synthetic oils, and non-conventional oils, and mixtures thereof, can be used unrefined, refined, or rerefined (the latter also known as regenerated or reprocessed oil). Unrefined oils are obtained directly from natural, synthetic or non-conventional materials and are used without further purification. These include, for example, shale oil obtained directly from dry distillation operations, oil derived from coal, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from the esterification process. Refined oils are similar to those discussed with respect to unrefined oils, except that refined oils are subjected to one or more refining or conversion steps to improve at least one lubricating oil property. Those skilled in the art are familiar with many purification or conversion processes. These processes include, for example, solvent extraction, secondary distillation, acid extraction, base extraction, filtration, leaching, hydrogenation, hydrorefining, and hydrogen finishing. Rerefined oil is obtained by a process similar to refined oil. However, the oil used earlier is used.

  Groups I, II, III, IV, and V have extensive classifications of base stocks developed and defined by the American Petroleum Institute to develop lubricant base oil guidelines (non-patent literature). 1). Group I substrates generally have a viscosity index of about 80-120 and contain greater than about 0.03% sulfur and less than about 90% saturation. Group II substrates generally have a viscosity index of about 80-120 and contain no more than about 0.03% sulfur and no less than about 90% saturation. Group III substrates generally have a viscosity index greater than about 120, and contain no more than about 0.03% sulfur and more than about 90% saturation. Group IV includes polyalphaolefins (PAO). Group V substrates include substrates not included in Groups I-IV. Table 1 summarizes the characteristics of each of these five groups.

  Natural oils include animal oils, vegetable oils (eg, castor oil and lard oil), and mineral oils. Animal and vegetable oils with suitable thermal oxidative stability can be used. Of the natural oils, mineral oil is preferred. Mineral oils vary widely according to their crude material, for example, whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful in the present invention. Natural oils also vary according to the method used for their production and purification, such as their distillation range and whether they are straight-run or cracked, hydrorefined, or solvent extracted.

Synthetic oils include hydrocarbon oils as well as non-hydrocarbon oils. Synthetic oils can be derived from processes such as chemical combinations (eg, polymerization, oligomerization, condensation, alkylation, acylation, etc.). At that time, a substance composed of smaller and simpler molecular species is made up (ie, synthesized) into a substance composed of larger and more complex molecular species. Synthetic oils include hydrocarbon oils such as polymerized and copolymerized olefins (eg, polybutylene, polypropylene, propylene-isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alpha olefin copolymers). A polyalphaolefin (PAO) oil base is a commonly used synthetic hydrocarbon oil. As an _example, PAO derived from _{C 8, C 10, C 12} , C 14 olefin or mixtures thereof, may be used. See Patent Literature 74, Patent Literature 75, and Patent Literature 76.

The number average molecular weight of PAO, which is a known material and is generally available on a large commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron, BP-Amoco et al., Is typically about 250 to about 3000. , Or above, the PAO may be made with a viscosity (100 ° C.) of about 100 mm ² / sec or less, or above. In addition, higher viscosity PAOs are commercially available and may be made with a viscosity (100 ° C.) of about 3000 mm ² / sec or less, or higher. The PAO typically consists of a relatively low molecular weight hydrogenated polymer or oligomer of an alpha olefin, including but not limited to about C ₂ to about C ₃₂ alpha olefin, and about C ₈ to about C ₁₆ alpha-olefin (1-octene, 1-decene, 1-dodecene) is preferred. Preferred polyalphaolefins are poly-1-octene, poly-1-decene, poly-1-dodecene, and mixtures thereof, and mixed olefin derived polyolefins. However, higher olefin dimers of about C _{14 to} C ₁₈ may be used to provide an acceptable low volatility low viscosity substrate. Depending on the viscosity grade and starting oligomers, the PAO may be mainly trimers and tetramers of the starting olefin, with a small amount of higher oligomers. This has a viscosity range of about 1.5-12 mm < ² > / sec.

The PAO fluid may conveniently be made by polymerization of alpha olefins in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst. This includes, for example, aluminum trichloride, boron trifluoride, or complexes of boron trifluoride and water, alcohols such as ethanol, propanol, or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. It is. For example, the methods disclosed by US Pat. Other descriptions of PAO synthesis are as follows: Patent Document 79, Patent Document 80, Patent Document 81, Patent Document 82, Patent Document 83, Patent Document 84, Patent Document 85, Patent Document 86, Patent Document 87, and Patent Document 88. To be found. Dimers of C _{14 to} C ₁₈ olefins are described in US Pat.

  Other useful synthetic lubricating base stocks (such as silicon-based oils or esters of phosphorus-containing acids) may also be used. Regarding examples of other synthetic lubricating base materials, there is basic research (Non Patent Literature 2).

［式中、Ｒ_１は、Ｈまたは炭素原子１〜約８個を有するヒドロカルビル基であり、Ｒ_２は、Ｈまたは炭素原子１〜約１２個のヒドロカルビル基であり、Ｒ_３は、炭素原子１〜１２個のヒドロカルビル基またはＮＨＲ_４（Ｒ_４は、炭素原子１〜約１２個のヒドロカルビル基である）である。好ましくは、Ｒ_１はｔｅｒｔ−ブチル基であり、Ｒ_２はＨであり、Ｒ_３はオクチル基である。］ In practicing the present invention, the deposit reducing additive comprises a mixture of a triaryl phosphite represented by Formula I and diphenylamine or phenyl-α-naphthylamine represented by Formulas II and III, respectively.

Wherein R ₁ is H or a hydrocarbyl group having 1 to about 8 carbon atoms, R ₂ is H or a hydrocarbyl group having 1 to about 12 carbon atoms, and R ₃ is a carbon atom 1 ˜12 hydrocarbyl groups or NHR _{4, where} R ₄ is a hydrocarbyl group of 1 to about 12 carbon atoms. Preferably, R ₁ is a tert-butyl group, R ₂ is H, and R ₃ is an octyl group. ]

  In practicing the present invention, the weight ratio of diphenylamine or phenyl-α-naphthylamine / alkylated triaryl phosphite used is generally from about 5: 1 to about 1: 5, preferably from about 2: 1 to about 1: It will be in the range of 2.

  Typically, the deposit reducing additive is from about 0.1% to about 2.0% by weight, preferably from about 0.4% to about 1%, based on the total weight of the composition, to the lubricating base oil. It will be added in the range of 0.0% by weight.

  The lubricating oil composition of the present invention comprises a major amount of oil of lubricating viscosity selected from the group consisting of Groups II, III, IV, and mixtures thereof, and a minor amount of the deposit reducing additive mixture of the present invention.

  The lubricating composition comprises one or more pour point depressants, rust inhibitors, metal deactivators, VI improvers, extreme pressure agents, demulsifiers, dispersants, solubilizers, antifoam agents, and dyes. It may be formulated with further additives.

  In the formulations shown in Tables 2 and 3, Irganox L06 is octylphenyl-α-naphthylamine sold by Ciba-Geigy, and Irgafos 168 is an alkyl sold by Ciba-Geigy. Triaryl phosphite.

  The formulated oils were subjected to performance tests listed in the table along with their test results. In the table, RPVOT refers to the rotary pressure bath oxidation test (ASTM D2222). The hot tube test is a test designed to simulate actual engine conditions. A test score of 10 indicates a heavy deposit, while a score of 0 indicates that there is no acceptable deposit.

Example 1 and Comparative Examples 1 to 4
A series of oils were prepared. This has the composition and properties shown in Table 2.

  This data shows the synergistic and deposit reducing effects of the additive mixture of the present invention. The data also shows that the oxidative stability of an oil is not an indicator of its tendency to deposit. Note that Comparative Oil 2 had a relatively high oxidative stability test result, but also had a very high deposit test result.

Examples 2-5 and Comparative Examples 5-8
Another series of oils was prepared. Their composition and properties are shown in Table 3.

  As mentioned above, the additive mixture of the present invention has an advantageous effect on the deposit formation tendency of group III and IV lubricating compositions. The data also show that the additive mixture of the present invention results in substantially less deposit formation when used in GTL base oils compared to other Group III base oils.

Claims (13)

A method for reducing deposit formation in a lubricating base oil selected from the group consisting of Group II, III, IV oils and mixtures thereof,
In the oil, an effective amount of a triaryl phosphite represented by the following formula I and a mixture of any of diphenylamine and phenyl-α-naphthylamine represented by the following formulas II and III respectively:

[Where:
R ₁ is H or a hydrocarbyl group having 1 to 8 carbon atoms;
R ₂ is H or a hydrocarbyl group having 1 to 12 carbon atoms;
R ₃ is a hydrocarbyl group having 1 to 12 carbon atoms or NHR ₄ (R ₄ is a hydrocarbyl group having 1 to 12 carbon atoms)]
A method for reducing deposit formation, comprising the step of adding   The method of claim 1, wherein the weight ratio of diphenylamine or phenyl-α-naphthylamine: triaryl phosphite in the mixture is in the range of 5: 1 to 1: 5.   The method of claim 2, wherein the amount of the mixture added to the base oil is in the range of 0.1 wt% to 2 wt%, based on the total weight of the composition. The method according to claim 3, wherein R ₁ is a tert-butyl group, R ₂ is H, and R ₃ is an octyl group.   The method of claim 4, wherein the oil is a Group III oil.   6. The method of claim 5, wherein the group III oil is a GTL oil. A lubricating oil composition having a reduced tendency to deposit as shown by hot tube testing,
A major amount of an oil of lubricating viscosity selected from the group consisting of Group II, III, IV oils and mixtures thereof; and a small amount of a triaryl phosphite represented by Formula I below and Formulas II and III below Mixtures of either diphenylamine and phenyl-α-naphthylamine respectively represented by:

[Where:
R ₁ is H or a hydrocarbyl group having 1 to 8 carbon atoms;
R ₂ is H or a hydrocarbyl group having 1 to 12 carbon atoms;
R ₃ is a hydrocarbyl group having 1 to 12 carbon atoms or NHR ₄ (R ₄ is a hydrocarbyl group having 1 to 12 carbon atoms)]
A lubricating oil composition comprising:   8. The composition of claim 7, wherein the weight ratio of diphenylamine or phenyl- [alpha] -naphthylamine: triaryl phosphite in the mixture is in the range of 5: 1 to 1: 5.   The composition of claim 8, wherein the amount of the mixture is in the range of 0.1 wt% to 2 wt%, based on the total weight of the composition. The composition according to claim 9, wherein R ₁ is a tert-butyl group, R ₂ is H, and R ₃ is an octyl group.   The composition of claim 10, wherein the base oil is a Group III base oil.   The composition of claim 11, wherein the Group III base oil is a GTL oil. A method for reducing deposit formation in a lubricating base oil selected from the group consisting of Group II, III, IV oils and mixtures thereof,
In the oil, an effective amount of a triaryl phosphite represented by the following formula I and a mixture of any of diphenylamine and phenyl-α-naphthylamine represented by the following formulas II and III respectively:

[Where:
R ₁ is H or a hydrocarbyl group having 1 to 8 carbon atoms;
R ₂ is H or a hydrocarbyl group having 1 to 12 carbon atoms;
R ₃ is a hydrocarbyl group having 1 to 12 carbon atoms or NHR ₄ (R ₄ is a hydrocarbyl group having 1 to 12 carbon atoms)]
Including the step of adding
The method for reducing deposit formation, wherein the weight ratio of diphenylamine or phenyl-α-naphthylamine: triaryl phosphite is in the range of 5: 1 to 1: 5.