Patent Application
20090143261
The invention relates generally to engine oil compositions. In one embodiment, engine oil compositions with improved fuel economy.
US government mandated standards for fuel economy and emissions have placed increasing demands on passenger car manufacturers. This in turn has resulted in automobile manufacturers requesting high quality engine oils used for passenger car motor oils (PCMOs).
Starting in 1995, automakers requested higher quality engine oils to help meet stringent federally mandated passenger car fuel economy and emissions standards. The International Lubricant Standardization and Approval Committee (ILSAC), working with API, ASTM, and SAE previously proposed a GF-3 Minimum Performance Standards for Passenger Car Motor Oils (PCMO) with significantly improved fuel economy and volatility requirements compared to previous GF-1 and GF-2 PCMO standards. In January 2004, ILSAC issued its latest Minimum Performance Standard for Engine Oils, ILSAC GF-4. Besides improved fuel efficiency, GF-4 requirements include improved oxidation resistance, improved high-temperature deposit control, better cam and lifter wear discrimination, improved low temperature wear protection, and improved low temperature used oil pumpability. ILSAC GF-4 oils also have reduced phosphorous and sulphur contents to provide enhanced emission system protection.
During the last five years, the petroleum industry has invested to make the higher viscosity index (VI) basestocks necessary to help meet these new engine oil requirements. In a number of patent publications and applications, i.e., US 2006/0289337, US2006/0201851, US2006/0016721, US2006/0016724, US2006/0076267, US2006/020185, US2006/013210, US2005/0241990, US2005/0077208, US2005/0139513, US2005/0139514, US2005/0133409, US2005/0133407, US2005/0261147, US2005/0261146, US2005/0261145, US2004/0159582, U.S. Pat. No. 7,018,525, U.S. Pat. No. 7,083,713, U.S. application Ser. Nos. 11/400570, 11/535165 and 11/613936, which are incorporated herein by reference, a Fischer Tropsch base oil is produced from a process in which the feed is a waxy feed recovered from a Fischer-Tropsch synthesis. The process comprises a complete or partial hydroisomerization dewaxing step, using a dual-functional catalyst or a catalyst that can isomerize paraffins selectively. Hydroisomerization dewaxing is achieved by contacting the waxy feed with a hydroisomerization catalyst in an isomerization zone under hydroisomerizing conditions. The Fischer-Tropsch synthesis products can be obtained by well-known processes such as, for example, the commercial SASOL® Slurry Phase Fischer-Tropsch technology, the commercial SHELL® Middle Distillate Synthesis (SMDS) Process, or by the non-commercial EXXON® Advanced Gas Conversion (AGC-21) process. Details of these processes and others are described in, for example, EP-A- 776959, EP-A-668342; U.S. Pat. Nos. 4,943,672, 5,059,299, 5,733,839, and RE39073 ; and US Published Application No. 2005/0227866, WO-A-9934917, WO-A-9920720 and WO-A-05107935. The Fischer-Tropsch synthesis product usually comprises hydrocarbons having 1 to 100, or even more than 100 carbon atoms, and typically includes paraffins, olefins and oxygenated products. Fischer Tropsch is a viable process to generate clean alternative hydrocarbon products.
There is still a need for engine oil compositions meeting ILSAC GF-4 specifications, utilizing less common hydrocarbon products and with improved fuel economy performance.
In one embodiment, there is provided an engine oil composition meeting at least one of ILSAC GF-4, API CI-4, API CJ4, ACEA A1, ACEA A5, ACEA B1, ACEA B5, ACEA C1, ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1 performance specifications, the composition comprising at least an isomerized base oil comprising a consecutive number of carbon atoms and having a CCS Viscosity at −35° C. of less than or equal to 7000 mPa, a T95-T5 boiling range distribution of less than or equal to 200° C., a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality of greater than 15, and an Oxidator BN of greater than 30 hours; and 0.05 to 40 wt %. of at least an additive selected from the group of metal detergents, dispersants, wear inhibitors, anti-oxidants, friction modifiers, viscosity modifiers, corrosion inhibitors, seal swelling agents, metal deactivators, anti-foamants, and mixtures thereof. The engine oil composition in one embodiment provides at least 1% fuel savings over a composition of the prior art without the isomerized base oil.
In another aspect, there is provided a method to improve fuel efficiency in the operations of an automobile/vehicle, the method comprises utilizing an engine oil composition at least an isomerized base oil comprising a consecutive number of carbon atoms and having a CCS Viscosity at −35° C. of less than or equal to 7000 mPa, a T95-T5 boiling range distribution of less than or equal to 200° C., a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality of greater than 15, and an Oxidator BN of greater than 30 hours; and 0.05 to 40 wt %. of at least an additive selected from the group of metal detergents, dispersants, wear inhibitors, anti-oxidants, friction modifiers, viscosity modifiers, corrosion inhibitors, seal swelling agents, metal deactivators, anti-foamants, and mixtures thereof.
The following terms will be used throughout the specification and will have the following meanings unless otherwise indicated.
“Fischer-Tropsch derived” means that the product, fraction, or feed originates from or is produced at some stage by a Fischer-Tropsch process. As used herein, “Fischer-Tropsch base oil” may be used interchangeably with “FT base oil,” “FTBO,” “GTL base oil” (GTL: gas-to-liquid), or “Fischer-Tropsch derived base oil.”
As used herein, “isomerized base oil” refers to a base oil made by isomerization of a waxy feed.
As used herein, a “waxy feed” comprises at least 40 wt % n-paraffins. In one embodiment, the waxy feed comprises greater than 50 wt % n-paraffins. In another embodiment, greater than 75 wt % n-paraffins. In one embodiment, the waxy feed also has very low levels of nitrogen and sulphur, e.g., less than 25 ppm total combined nitrogen and sulfur, or in other embodiments less than 20 ppm. Examples of waxy feeds include slack waxes, deoiled slack waxes, refined foots oils, waxy lubricant raffinates, n-paraffin waxes, NAO waxes, waxes produced in chemical plant processes, deoiled petroleum derived waxes, microcrystalline waxes, Fischer-Tropsch waxes, and mixtures thereof In one embodiment, the waxy feeds have a pour point of greater than 50° C. In another embodiment, greater than 60° C.
“Kinematic viscosity” is a measurement in mm2/s of the resistance to flow of a fluid under gravity, determined by ASTM D445-06.
“Viscosity index” (VI) is an empirical, unit-less number indicating the effect of temperature change on the kinematic viscosity of the oil. The higher the VI of an oil, the lower its tendency to change viscosity with temperature. Viscosity index is measured according to ASTM D 2270-04.
Cold-cranking simulator apparent viscosity (CCS VIS) is a measurement in millipascal seconds, mPa.s to measure the viscometric properties of lubricating base oils under low temperature and low shear. CCS VIS is determined by ASTM D 5293-04.
The boiling range distribution of base oil, by wt %, is determined by simulated distillation (SIMDIS) according to ASTM D 6352-04, “Boiling Range Distribution of Petroleum Distillates in Boiling Range from 174 to 700° C. by Gas Chromatography.”
“Noack volatility” is defined as the mass of oil, expressed in weight %, which is lost when the oil is heated at 250° C. with a constant flow of air drawn through it for 60 min., measured according to ASTM D5800-05, Procedure B.
Brookfield viscosity is used to determine the internal fluid-friction of a lubricant during cold temperature operation, which can be measured by ASTM D 2983-04.
“Pour point” is a measurement of the temperature at which a sample of base oil will begin to flow under certain carefully controlled conditions, which can be determined as described in ASTM D 5950-02.
“Auto ignition temperature” is the temperature at which a fluid will ignite spontaneously in contact with air, which can be determined according to ASTM 659-78.
“Ln” refers to natural logarithm with base “e.”
“Traction coefficient” is an indicator of intrinsic lubricant properties, expressed as the dimensionless ratio of the friction force F and the normal force N, where friction is the mechanical force which resists movement or hinders movement between sliding or rolling surfaces. Traction coefficient can be measured with an MTM Traction Measurement System from PCS Instruments, Ltd., configured with a polished 19 mm diameter ball (SAE AISI 52100 steel) angled at 220 to a flat 46 mm diameter polished disk (SAE AISI 52100 steel). The steel ball and disk are independently measured at an average rolling speed of 3 meters per second, a slide to roll ratio of 40 percent, and a load of 20 Newtons. The roll ratio is defined as the difference in sliding speed between the ball and disk divided by the mean speed of the ball and disk, i.e. roll ratio=(Speed1−Speed2)/((Speed1+Speed2)−/2).
As used herein, “consecutive numbers of carbon atoms” means that the base oil has a distribution of hydrocarbon molecules over a range of carbon numbers, with every number of carbon numbers in-between. For example, the base oil may have hydrocarbon molecules ranging from C22 to C36 or from C30 to C60 with every carbon number in-between. The hydrocarbon molecules of the base oil differ from each other by consecutive numbers of carbon atoms, as a consequence of the waxy feed also having consecutive numbers of carbon atoms. For example, in the Fischer-Tropsch hydrocarbon synthesis reaction, the source of carbon atoms is CO and the hydrocarbon molecules are built up one carbon atom at a time. Petroleum-derived waxy feeds have consecutive numbers of carbon atoms. In contrast to an oil based on poly-alpha-olefin (“PAO”), the molecules of an isomerized base oil have a more linear structure, comprising a relatively long backbone with short branches. The classic textbook description of a PAO is a star-shaped molecule, and in particular tridecane, which is illustrated as three decane molecules attached at a central point. While a star-shaped molecule is theoretical, nevertheless PAO molecules have fewer and longer branches that the hydrocarbon molecules that make up the isomerized base oil disclosed herein.
“Molecules with cycloparaffinic functionality” mean any molecule that is, or contains as one or more substituents, a monocyclic or a fused multicyclic saturated hydrocarbon group.
“Molecules with monocycloparaffinic functionality” mean any molecule that is a monocyclic saturated hydrocarbon group of three to seven ring carbons or any molecule that is substituted with a single monocyclic saturated hydrocarbon group of three to seven ring carbons.
“Molecules with multicycloparaffinic functionality” mean any molecule that is a fused multicyclic saturated hydrocarbon ring group of two or more fused rings, any molecule that is substituted with one or more fused multicyclic saturated hydrocarbon ring groups of two or more fused rings, or any molecule that is substituted with more than one monocyclic saturated hydrocarbon group of three to seven ring carbons.
Molecules with cycloparaffinic functionality, molecules with monocycloparaffinic functionality, and molecules with multicycloparaffinic functionality are reported as weight percent and are determined by a combination of Field Ionization Mass Spectroscopy (FIMS), HPLC-UV for aromatics, and Proton NMR for olefins, further fully described herein.
Oxidator BN measures the response of a lubricating oil in a simulated application. High values, or long times to adsorb one liter of oxygen, indicate good stability. Oxidator BN can be measured via a Dornte-type oxygen absorption apparatus (R. W. Dornte “Oxidation of White Oils,” Industrial and Engineering Chemistry, Vol. 28, page 26, 1936), under 1 atmosphere of pure oxygen at 340° F., time to absorb 1000 ml of O2 by 100 g. of oil is reported. In the Oxidator BN test, 0.8 ml of catalyst is used per 100 grams of oil. The catalyst is a mixture of soluble metal-naphthenates simulating the average metal analysis of used crankcase oil. The additive package is 80 millimoles of zinc bispolypropylenephenyldithiophosphate per 100 grams of oil.
Molecular characterizations can be performed by methods known in the art, including Field Ionization Mass Spectroscopy (FIMS) and n-d-M analysis (ASTM D 3238-95 (Re-approved 2005) with normalization). In FIMS, the base oil is characterized as alkanes and molecules with different numbers of unsaturations. The molecules with different numbers of unsaturations may be comprised of cycloparaffins, olefins, and aromatics. If aromatics are present in significant amount, they would be identified as 4-unsaturations. When olefins are present in significant amounts, they would be identified as 1-unsaturations. The total of the 1-unsaturations, 2-unsaturations, 3-unsaturations, 4-unsaturations, 5-unsaturations, and 6-unsaturations from the FIMS analysis, minus the wt % olefins by proton NMR, and minus the wt % aromatics by HPLC-UV is the total weight percent of molecules with cycloparaffinic functionality. If the aromatics content was not measured, it was assumed to be less than 0.1 wt % and not included in the calculation for total weight percent of molecules with cycloparaffinic functionality. The total weight percent of molecules with cycloparaffinic functionality is the sum of the weight percent of molecules with monocyclopraffinic functionality and the weight percent of molecules with multicycloparaffinic functionality.
Molecular weights are determined by ASTM D2503-92(Reapproved 2002). The method uses thermoelectric measurement of vapour pressure (VPO). In circumstances where there is insufficient sample volume, an alternative method of ASTM D2502-04 may be used; and where this has been used it is indicated.
Density is determined by ASTM D4052-96 (Reapproved 2002). The sample is introduced into an oscillating sample tube and the change in oscillating frequency caused by the change in the mass of the tube is used in conjunction with calibration data to determine the density of the sample.
Weight percent olefins can be determined by proton-NMR according to the steps specified herein. In most tests, the olefins are conventional olefins, i.e. a distributed mixture of those olefin types having hydrogens attached to the double bond carbons such as: alpha, vinylidene, cis, trans, and tri-substituted, with a detectable allylic to olefin integral ratio between 1 and 2.5. When this ratio exceeds 3, it indicates a higher percentage of tri or tetra substituted olefins being present, thus other assumptions known in the analytical art can be made to calculate the number of double bonds in the sample. A solution of 5-10% of the sample in deuterochloroform can be prepared, giving a normal proton spectrum of at least 12 ppm spectral width. Tetramethylsilane (TMS) can be used as an internal reference standard. The instrument used to acquire the spectrum and reference the chemical shift has sufficient gain range to acquire a signal without overloading the receiver/ADC, with a minimum signal digitization dynamic range of at least 65,000 when a 30 degree pulse is applied. The intensities of the proton signals in the region of 0.5-1.9 ppm (methyl, methylene and methine groups), 1.9-2.2 ppm (allylic) and between 6.0-4.5 ppm (olefin) are measured. Using the average molecular weight (estimated by vapor pressure osmometry by ASTM D 2503-92[re-approved 2002]) of each distillate range paraffin feed, the following can be calculated: (1) the average molecular formula of the saturated hydrocarbons; (2) the average molecular formula of the olefins; (3) the total integral intensity (i.e. the sum of all the integral intensities); (4) the integral intensity per sample hydrogen (i.e. the total integral intensity divided by the number of hydrogens in the formula; (5) the number of olefin hydrogens (i.e. the olefin integral divided by the integral per hydrogen); (6) the number of double bonds (i.e. the olefin hydrogen multiplied by the hydrogens in the olefin formula divided by 2); and (7) the weight percent olefins (i.e. 100 multiplied by the number of double bonds multiplied by the number of hydrogens in a typical olefin molecule divided by the number of hydrogens in a typical distillate range paraffin feed molecule). This Proton NMR procedure to calculate the olefin content of the sample works best when the olefin content is low, e.g., less than about 15 weight percent.
Weight percent aromatics in one embodiment can be measured by HPLC-UV. In one embodiment, the test is conducted using a Hewlett Packard 1050 Series Quaternary Gradient High Performance Liquid Chromatography (HPLC) system, coupled with a HP 1050 Diode-Array UV-Vis detector interfaced to an HP Chem-station. Identification of the individual aromatic classes in the highly saturated base oil can be made on the basis of the UV spectral pattern and the elution time. The amino column used for this analysis differentiates aromatic molecules largely on the basis of their ring- number (or double-bond number). Thus, the single ring aromatic containing molecules elute first, followed by the polycyclic aromatics in order of increasing double bond number per molecule. For aromatics with similar double bond character, those with only alkyl substitution on the ring elute sooner than those with naphthenic substitution. Unequivocal identification of the various base oil aromatic hydrocarbons from their UV absorbance spectra can be accomplished recognizing that their peak electronic transitions are all red-shifted relative to the pure model compound analogs to a degree dependent on the amount of alkyl and naphthenic substitution on the ring system. Quantification of the eluting aromatic compounds can be made by integrating chromatograms made from wavelengths optimized for each general class of compounds over the appropriate retention time window for that aromatic. Retention time window limits for each aromatic class can be determined by manually evaluating the individual absorbance spectra of eluting compounds at different times and assigning them to the appropriate aromatic class based on their qualitative similarity to model compound absorption spectra.
Weight percent aromatic carbon (“Ca”), weight percent naphthenic carbon (“Cn”) and weight percent paraffinic carbon (“Cp”) in one embodiment can be measured by ASTM D3238-95 (Reapproved 2005) with normalization. ASTM D3238-95 (Reapproved 2005) is the Standard Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method. This method is for “olefin free” feedstocks, i.e., having an olefin content of 2 wt % or less. The normalization process consists of the following: A) If the Ca value is less than zero, Ca is set to zero, and Cn and Cp are increased proportionally so that the sum is 100%. B) If the Cn value is less than zero, Cn is set to zero, and Ca and Cp are increased proportionally so that the sum is 100%; and C) If both Cn and Ca are less than zero, Cn and Ca are set to zero, and Cp is set to 100%.
HPLC-UV Calibration. In one embodiment, HPLC-UV can be used for identifying classes of aromatic compounds even at very low levels, e.g., multi-ring aromatics typically absorb 10 to 200 times more strongly than single-ring aromatics. Alkyl-substitution affects absorption by 20%. Integration limits for the co-eluting 1-ring and 2-ring aromatics at 272 nm can be made by the perpendicular drop method. Wavelength dependent response factors for each general aromatic class can be first determined by constructing Beer's Law plots from pure model compound mixtures based on the nearest spectral peak absorbances to the substituted aromatic analogs. Weight percent concentrations of aromatics can be calculated by assuming that the average molecular weight for each aromatic class was approximately equal to the average molecular weight for the whole base oil sample.
NMR analysis. In one embodiment, the weight percent of all molecules with at least one aromatic function in the purified mono-aromatic standard can be confirmed via long-duration carbon 13 NMR analysis. The NMR results can be translated from % aromatic carbon to % aromatic molecules (to be consistent with HPLC-UV and D 2007) knowing that 95-99% of the aromatics in highly saturated base oils are single-ring aromatics. In another test to accurately measure low levels of all molecules with at least one aromatic function by NMR, the standard D 5292-99 (Reapproved 2004) method can be modified to give a minimum carbon sensitivity of 500:1 (by ASTM standard practice E 386) with a 15-hour duration run on a 400-500 MHz NMR with a 10-12 mm Nalorac probe. Acorn PC integration software can be used to define the shape of the baseline and consistently integrate.
Extent of branching refers to the number of alkyl branches in hydrocarbons. Branching and branching position can be determined using carbon-13 (13C) NMR according to the following nine-step process: 1) Identify the CH branch centers and the CH3 branch termination points using the DEPT Pulse sequence (Doddrell, D. T.; D. T. Pegg; M. R. Bendall, Journal of Magnetic Resonance 1982, 48, 323ff.). 2) Verify the absence of carbons initiating multiple branches (quaternary carbons) using the APT pulse sequence (Patt, S. L.; J. N. Shoolery, Journal of Magnetic Resonance 1982, 46, 535ff.). 3) Assign the various branch carbon resonances to specific branch positions and lengths using tabulated and calculated values known in the art (Lindeman, L. P., Journal of Qualitative Analytical Chemistry 43, 1971 1245ff; Netzel, D. A., et. al., Fuel, 60, 1981, 307ff). 4) Estimate relative branching density at different carbon positions by comparing the integrated intensity of the specific carbon of the methyl/alkyl group to the intensity of a single carbon (which is equal to total integral/number of carbons per molecule in the mixture). For the 2-methyl branch, where both the terminal and the branch methyl occur at the same resonance position, the intensity is divided by two before estimating the branching density. If the 4-methyl branch fraction is calculated and tabulated, its contribution to the 4+methyls is subtracted to avoid double counting. 5) Calculate the average carbon number. The average carbon number is determined by dividing the molecular weight of the sample by 14 (the formula weight of CH2). 6) The number of branches per molecule is the sum of the branches found in step 4. 7) The number of alkyl branches per 100 carbon atoms is calculated from the number of branches per molecule (step 6) times 100/average carbon number. 8) Estimate Branching Index (BI) by 1H NMR Analysis, which is presented as percentage of methyl hydrogen (chemical shift range 0.6-1.05 ppm) among total hydrogen as estimated by NMR in the liquid hydrocarbon composition. 9) Estimate Branching proximity (BP) by 13C NMR, which is presented as percentage of recurring methylene carbons—which are four or more carbons away from the end group or a branch (represented by a NMR signal at 29.9 ppm) among total carbons as estimated by NMR in the liquid hydrocarbon composition. The measurements can be performed using any Fourier Transform NMR spectrometer, e.g., one having a magnet of 7.0 T or greater. After verification by Mass Spectrometry, UV or an NMR survey that aromatic carbons are absent, the spectral width for the 13C NMR studies can be limited to the saturated carbon region, 0-80 ppm vs. TMS (tetramethylsilane). Solutions of 25-50 wt. % in chloroform-d1 are excited by 30 degrees pulses followed by a 1.3 seconds (sec.) acquisition time. In order to minimize non-uniform intensity data, the broadband proton inverse-gated decoupling is used during a 6 sec. delay prior to the excitation pulse and on during acquisition. Samples are doped with 0.03 to 0.05 M Cr (acac)3 (tris(acetylacetonato)-chromium (III)) as a relaxation agent to ensure full intensities are observed. The DEPT and APT sequences can be carried out according to literature descriptions with minor deviations described in the Varian or Bruker operating manuals. DEPT is Distortionless Enhancement by Polarization Transfer. The DEPT 45 sequence gives a signal all carbons bonded to protons. DEPT 90 shows CH carbons only. DEPT 135 shows CH and CH3 up and CH2 180 degrees out of phase (down). APT is attached proton test, known in the art. It allows all carbons to be seen, but if CH and CH3 are up, then quaternaries and CH2 are down. The branching properties of the sample can be determined by 13C NMR using the assumption in the calculations that the entire sample was iso-paraffinic. The unsaturates content may be measured using Field Ionization Mass Spectroscopy (FIMS).
In one embodiment, the engine oil composition comprises optional additives in a matrix of base oil or base oil blends comprising xxxxxx.
Base Oil Component: In one embodiment, the base oil or blend thereof comprises at least an isomerized base oil which the product itself, its fraction, or feed originates from or is produced at some stage by isomerization of a waxy feed from a Fischer-Tropsch process (“Fischer-Tropsch derived base oils”). In another embodiment, the base oil comprises at least an isomerized base oil made from a substantially paraffinic wax feed (“waxy feed”). In a third embodiment, the isomerized base oil comprises mixtures of products made from a substantially paraffinic wax feed as well as products made from a waxy feed from a Fischer-Tropsch process.
Fischer-Tropsch derived base oils are disclosed in a number of patent publications, including for example U.S. Pat. Nos. 6,080,301, 6,090,989, and 6,165,949, and US Patent Publication No. US2004/0079678A1, US20050133409, US20060289337. The Fischer-Tropsch process is a catalyzed chemical reaction in which carbon monoxide and hydrogen are converted into liquid hydrocarbons of various forms including a light reaction product and a waxy reaction product, with both being substantially paraffinic.
In one embodiment the isomerized base oil has consecutive numbers of carbon atoms and has less than 25 wt % naphthenic carbon by n-d-M with normalization. In another embodiment, the amount of naphthenic carbon is less than 10 wt. %. In yet another embodiment the isomerized base oil made from a waxy feed has a kinematic viscosity at 100° C. between 1.5 and 3.5 mm2/s.
In one embodiment, the isomerized base oil is made by a process in which the hydroisomerization dewaxing is performed at conditions sufficient for the base oil to have: a) a weight percent of all molecules with at least one aromatic functionality less than 0.30; b) a weight percent of all molecules with at least one cycloparaffinic functionality greater than 10; c) a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality greater than 20 and d) a viscosity index greater than 28×Ln (Kinematic viscosity at 100° C.)+80.
In another embodiment, the isomerized base oil is made from a process in which the highly paraffinic wax is hydroisomerized using a shape selective intermediate pore size molecular sieve comprising a noble metal hydrogenation component, and under conditions of 600-750° F. (315-399° C.) In the process, the conditions for hydroisomerization are controlled such that the conversion of the compounds boiling above 700° F. (371° C.) in the wax feed to compounds boiling below 700° F. (371° C.) is maintained between 10 wt % and 50 wt %. A resulting isomerized base oil has a kinematic viscosity of between 1.0 and 3.5 mm2/s at 100° C. and a Noack volatility of less than 50 weight %. The base oil comprises greater than 3 weight % molecules with cycloparaffinic functionality and less than 0.30 weight percent aromatics.
In one embodiment the isomerized base oil has a Noack volatility less than an amount calculated by the following equation: 1000×(Kinematic Viscosity at 100° C.)−2.7. In another embodiment, the isomerized base oil has a Noack volatility less than an amount calculated by the following equation: 900×(Kinematic Vicosity at 100° C.)−2.8. In a third embodiment, the isomerized base oil has a Kinematic Viscosity at 100° C. of >1.808 mm2/s and a Noack volatility less than an amount calculated by the following equation: 1.286+20 (kV100)−1.5+551.8 e−kv100, where kv100 is the kinematic viscosity at 100° C. In a fourth embodiment, the isomerized base oil has a kinematic viscosity at 100° C. of less than 4.0 mm2/s, and a wt % Noack volatility between 0 and 100. In a fifth embodiment, the isomerized base oil has a kinematic viscosity between 1.5 and 4.0 mm2/s and a Noack volatility less than the Noack volatility calculated by the following equation: 160−40 (Kinematic Viscosity at 100° C.).
In one embodiment, the isomerized base oil has a kinematic viscosity at 100° C. in the range of 2.4 and 3.8 mm2/s and a Noack volatility less than an amount defined by the equation: 900×(Kinematic Viscosity at 100° C.)−2.8−15). For kinematic viscosities in the range of 2.4 and 3.8 mm2/s, the equation: 900×(Kinematic Viscosity at 100° C.)−2.8−15) provides a lower Noack volatility than the equation: 160−40 (Kinematic Viscosity at 100° C.)
In one embodiment, the isomerized base oil is made from a process in which the highly paraffinic wax is hydroisomerized under conditions for the base oil to have a kinematic viscosity at 100° C. of 3.6 to 4.2 mm2/s, a viscosity index of greater than 130, a wt % Noack volatility less than 12, a pour point of less than −9° C.
In one embodiment, the isomerized base oil has an aniline point, in degrees F, greater than 200 and less than or equal to an amount defined by the equation: 36×Ln(Kinematic Viscosity at 100° C., in mm2/s)+200.
In one embodiment, the isomerized base oil has an auto-ignition temperature (AIT) greater than the AIT defined by the equation: AIT in ° C.=1.6×(Kinematic Viscosity at 40° C., in mm2/s)+300. In a second embodiment, the base oil as an AIT of greater than 329° C. and a viscosity index greater than 28×Ln (Kinematic Viscosity at 100° C., in mm2/s)+100.
In one embodiment, the isomerized base oil has a relatively low traction coefficient, specifically, its traction coefficient is less than an amount calculated by the equation: traction coefficient=0.009×Ln (kinematic viscosity in mm2/s)−0.001, wherein the kinematic viscosity in the equation is the kinematic viscosity during the traction coefficient measurement and is between 2 and 50 mm2/s. In one embodiment, the isomerized base oil has a traction coefficient of less than 0.023 (or less than 0.021) when measured at a kinematic viscosity of 15 mm2/s and at a slide to roll ratio of 40%. In another embodiment the isomerized base oil has a traction coefficient of less than 0.017 when measured at a kinematic viscosity of 15 mm2/s and at a slide to roll ratio of 40%. In another embodiment the isomerized base oil has a viscosity index greater than 150 and a traction coefficient less than 0.015 when measured at a kinematic viscosity of 15 mm2/s and at a slide to roll ratio of 40 percent.
In some embodiments, the isomerized base oil having low traction coefficients also displays a higher kinematic viscosity and higher boiling points. In one embodiment, the base oil has a traction coefficient less than 0.015, and a 50 wt % boiling point greater than 565° C. (1050° F.). In another embodiment, the base oil has a traction coefficient less than 0.011 and a 50 wt % boiling point by ASTM D 6352-04 greater than 582° C. (1080° F.).
In some embodiments, the isomerized base oil having low traction coefficients also displays unique branching properties by NMR, including a branching index less than or equal to 23.4, a branching proximity greater than or equal to 22.0, and a Free Carbon Index between 9 and 30. In one embodiment, the base oil has at least 4 wt % naphthenic carbon, in another embodiment, at least 5 wt % naphthenic carbon by n-d-M analysis by ASTM D 3238-95 (Reapproved 2005) with normalization.
In one embodiment, the isomerized base oil is produced in a process wherein the intermediate oil isomerate comprises paraffinic hydrocarbon components, and in which the extent of branching is less than 7 alkyl branches per 100 carbons, and wherein the base oil comprises paraffinic hydrocarbon components in which the extent of branching is less than 8 alkyl branches per 100 carbons and less than 20 wt % of the alkyl branches are at the 2 position. In one embodiment, the FT base oil has a pour point of less than −8° C.; a kinematic viscosity at 100° C. of at least 3.2 mm2/s; and a viscosity index greater than a viscosity index calculated by the equation of=22×Ln (kinematic viscosity at 100° C.)+132.
In one embodiment, the base oil comprises greater than 10 wt. % and less than 70 wt. % total molecules with cycloparaffinic functionality, and a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality greater than 15.
In one embodiment, the isomerized base oil has an average molecular weight between 600 and 1100, and an average degree of branching in the molecules between 6.5 and 10 alkyl branches per 100 carbon atoms. In another embodiment, the isomerized base oil has a kinematic viscosity between about 8 and about 25 mm2/s and an average degree of branching in the molecules between 6.5 and 10 alkyl branches per 100 carbon atoms.
In one embodiment, the isomerized base oil is obtained from a process in which the highly paraffinic wax is hydroisomerized at a hydrogen to feed ratio from 712.4 to 3562 liter H2/liter oil, for the base oil to have a total weight percent of molecules with cycloparaffinic functionality of greater than 10, and a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality of greater than 15. In another embodiment, the base oil has a viscosity index greater than an amount defined by the equation: 28×Ln (Kinematic viscosity at 100° C.)+95. In a third embodiment, the base oil comprises a weight percent aromatics less than 0.30; a weight percent of molecules with cycloparaffinic functionality greater than 10; a ratio of weight percent of molecules with monocycloparaffinic functionality to weight percent of molecules with multicycloparaffinic functionality greater than 20; and a viscosity index greater than 28×Ln (Kinematic Viscosity at 100° C.)+110. In a fourth embodiment, the base oil further has a kinematic viscosity at 100° C. greater than 6 mm2/s. In a fifth embodiment, the base oil has a weight percent aromatics less than 0.05 and a viscosity index greater than 28×Ln (Kinematic Viscosity at 100° C.)+95. In a sixth embodiment, the base oil has a weight percent aromatics less than 0.30, a weight percent molecules with cycloparaffinic functionality greater than the kinematic viscosity at 100° C., in mm2/s, multiplied by three, and a ratio of molecules with monocycloparaffinic functionality to molecules with multicycloparaffinic functionality greater than 15.
In one embodiment, the isomerized base oil contains between 2 and 10 wt % naphthenic carbon as measured by n-d-M. In one embodiment, the base oil has a kinematic viscosity of 1.5-3.0 mm2/s at 100° C. and 2-3 wt % naphthenic carbon. In another embodiment, a kinematic viscosity of 1.8-3.5 mm2/s at 100° C. and 2.5-4 wt % naphthenic carbon. In a third embodiment, a kinematic viscosity of 3-6 mm2/s at 100° C. and 2.7-5 wt % naphthenic carbon. In a fourth embodiment, a kinematic viscosity of 10-30 mm2/s at 100° C. and between greater than 5.2 % and less than 25 wt % naphthenic carbon.
In one embodiment, the isomerized base oil has an average molecular weight greater than 475; a viscosity index greater than 140, and a weight percent olefins less than 10. The base oil improves the air release and low foaming characteristics of the mixture when incorporated into the engine oil composition.
In one embodiment, the isomerized base oil is a FT base oil having a kinematic viscosity at 100° C. between 3 mm2/s and 10 mm2/s; a viscosity index between 135 and 160; CCS VIS in the range of 1,000-7,500 mPa.s at −35° C.; pour point in the range of −20 and −30° C.; Oxidator BN of 35 to 50 hours; and Noack volatility in wt. % of 2 to 20 as measured by ASTM D5800-05 Procedure B.
In one embodiment, the engine oil composition employs a base oil that consists of at least one of the isomerized base oils described above. In another embodiment, the composition consists essentially of at least a Fischer-Tropsch base oil. In yet another embodiment, the composition employs at least a Fischer-Tropsch base oil and optionally 5 to 30 wt. % of at least another type of oil, e.g., lubricant base oils selected from Group I, II, III, IV, and V lubricant base oils as defined in the API Interchange Guidelines, and mixtures thereof Examples include conventionally used mineral oils, synthetic hydrocarbon oils or synthetic ester oils, or mixtures thereof depending on the application. Mineral lubricating oil base stocks can be any conventionally refined base stocks derived from paraffinic, naphthenic and mixed base crudes. Synthetic lubricating oils that can be used include esters of glycols and complex esters. Other synthetic oils that can be used include synthetic hydrocarbons such as polyalphaolefins; alkyl benzenes, e.g., alkylate bottoms from the alkylation of benzene with tetrapropylene, or the copolymers of ethylene and propylene; silicone oils, e.g., ethyl phenyl polysiloxanes, methyl polysiloxanes, etc., polyglycol oils, e.g., those obtained by condensing butyl alcohol with propylene oxide; etc. Other suitable synthetic oils include the polyphenyl ethers, e.g., those having from 3 to 7 ether linkages and 4 to 8 phenyl groups. Other suitable synthetic oils include polyisobutenes, and alkylated aromatics such as alkylated naphthalenes.
Additional Components: In one embodiment, the engine oil further comprises at least an additive selected from the group of metal detergents, dispersants, wear inhibitors, oxidation inhibitors, friction modifiers, viscosity modifiers, corrosion inhibitors, seal swelling agents, metal deactivators, antifoamers, and mixtures thereof, in a sufficient amount to provide the desired effects. In one embodiment, this sufficient amount is 0.05 to 40 wt. %. In another embodiment, it is between 1 to 35 wt. %. In a third embodiment, from 5 to 25 wt. %.
In one embodiment, the additives are incorporated as an “additive package.” As used herein, the term “additive package” means any combination of additives listed above for engine oil compositions. In one embodiment, the additive package is a commercially available package, added in an amount from about 1.5% to about 30% by weight of the finished composition. In one embodiment, the additive package is a commercially available package from the Lubrizol Corporation or from Chevron Oronite Company LLC.
Dispersants: Dispersants are generally used to maintain in suspension insoluble materials resulting from oxidation during use, thus preventing sludge flocculation and precipitation or deposition on engine parts. In one embodiment, the composition comprises 0.3 to about 15.0 wt. % of at least a dispersant. In a second embodiment, from 3.0 to about 7.0 wt. % of at least a dispersant. Examples of dispersants include nitrogen-containing ashless (metal-free) dispersants. An ashless dispersant generally comprises an oil soluble polymeric hydrocarbon backbone having functional groups that are capable of associating with particles to be dispersed. Other examples of dispersants include, but are not limited to, amines, alcohols, amides, or ester polar moieties attached to the polymer backbones via bridging groups.
In one embodiment, the engine oil composition comprises an ashless dispersant selected from oil soluble salts, esters, amino-esters, amides, imides, and oxazolines of long chain hydrocarbon substituted mono and dicarboxylic acids or their anhydrides; thiocarboxylate derivatives of long chain hydrocarbons, long chain aliphatic hydrocarbons having a polyamine attached directly thereto; and Mannich condensation products formed by condensing a long chain substituted phenol with formaldehyde and polyalkylene polyamine. In another embodiment, the composition comprises at least a carboxylic dispersant. Carboxylic dispersants are reaction products of carboxylic acylating agents (acids, anhydrides, esters, etc.) comprising at least 34 and preferably at least 54 carbon atoms with nitrogen containing compounds (such as amines), organic hydroxy compounds (such as aliphatic compounds including monohydric and polyhydric alcohols, or aromatic compounds including phenols and naphthols), and/or basic inorganic materials. These reaction products include imides, amides, and esters, e.g., succinimide dispersants.
Other suitable ashless dispersants may also include amine dispersants, which are reaction products of relatively high molecular weight aliphatic halides and amines, preferably polyalkylene polyamines. Other examples may further include “Mannich dispersants,” which are reaction products of alkyl phenols in which the alkyl group contains at least 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). In other embodiments, suitable ashless dispersants may even include post-treated dispersants, which are obtained by reacting carboxylic, amine or Mannich dispersants with reagents such as dimercaptothiazoles, urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitrile epoxides, boron compounds and the like. Suitable ashless dispersants may be polymeric, which are interpolymers of oil-solubilizing monomers such as decyl methacrylate, vinyl decyl ether and high molecular weight olefins with monomers containing polar substitutes.
In one embodiment, an ethylene carbonate-treated bissuccinimide derived from a polyisobutylene having a number average molecular weight of about 2300 Daltons is used as the ashless dispersant. In yet another embodiment, the engine oil composition comprises an ethylene-carbonate treated bissuccinimide dispersant derived from a polyisobutylene succinic anhydride, wherein the polyisobutylene chain has a number average molecular weight of about 2300 Daltons (“PIBSA 2300”) in an amount of about 6.5 wt. %.
Viscosity Index Improvers (Modifiers): The viscosity index of an engine oil base stock can be increased, or improved, by incorporating therein certain polymeric materials that function as viscosity modifiers (VM) or viscosity index improvers (VII) in an amount of 0.3 to 25 wt. %. of the final weight of the engine oil. Examples include but are not limited to olefin copolymers, such as ethylene-propylene copolymers, styrene-isoprene copolymers, hydrated styrene-isoprene copolymers, polybutene, polyisobutylene, polymethacrylates, vinylpyrrolidone and methacrylate copolymers and dispersant type viscosity index improvers. These viscosity modifiers can optionally be grafted with grafting materials such as, for example, maleic anhydride, and the grafted material can be reacted with, for example, amines, amides, nitrogen-containing heterocyclic compounds or alcohol, to form multifunctional viscosity modifiers (dispersant-viscosity modifiers).
In one embodiment, the engine oil composition comprises about 0.3 to 15 wt. % of an ethylene propylene copolymer viscosity index modifier. Other examples of viscosity modifiers include star polymers, e.g., a star polymer comprising isoprene/styrene/isoprene triblock. Yet other examples of viscosity modifiers include poly alkyl(meth)acrylates of low Brookfield viscosity and high shear stability, functionalized poly alkyl(meth)acrylates with dispersant properties of high Brookfield viscosity and high shear stability, polyisobutylene having a weight average molecular weight ranging from 700 to 2,500 Daltons and mixtures thereof.
Friction Modifiers: In one embodiment, the lubricating oil composition further comprises at least a friction modifier, e.g., a sulfur-containing molybdenum compound. In some embodiments, the composition does not contain any friction modifier at all (or just a minimal amount, e.g., less than 0.1 wt. %) while still providing excellent fuel economy performance. Certain sulfur-containing organo-molybdenum compounds are known to modify friction in lubricating oil compositions, while also offering antioxidant and antiwear credits. Examples of oil soluble organo-molybdenum compounds include dithiocarbamates, dithiophosphates, dithiophosphinates, xanthates, thioxanthates, sulfides, and the like, and mixtures thereof. In another embodiment, the composition employs a molybdenum succinimide complex as friction modifier in an amount of 0.15 to about 1.5 wt. %. In a third embodiment, the engine oil composition comprises at least a mono-, di- or triester of a tertiary hydroxyl amine and a fatty acid as a friction modifying fuel economy additive. In another embodiment, the friction modifier is selected from the group of succinamic acid, succinimide, and mixtures thereof. In yet another embodiment, the friction modifier is selected from an aliphatic fatty amine, an ether amine, an alkoxylated aliphatic fatty amine, an alkoxylated ether amine, an oil-soluble aliphatic carboxylic acid, a polyol ester, a fatty acid amide, an imidazoline, a tertiary amine, a hydrocarbyl succinic anhydride or acid reacted with an ammonia or a primary amine, and mixtures thereof.
Seal swelling agents: Seal fixes are also termed seal swelling agents or seal pacifiers. They are often employed in lubricant or additive compositions to insure proper elastomer sealing, and prevent premature seal failures and leakages. In one embodiment, the composition further includes at least a seal swell agent selected from oil-soluble, saturated, aliphatic, or aromatic hydrocarbon esters such as di-2-ethylhexylphthalate, mineral oils with aliphatic alcohols such as tridecyl alcohol, triphosphite ester in combination with a hydrocarbonyl-substituted phenol, and di-2-ethylhexylsebacate.
Corrosion inhibitors (Anti-corrosive agents): These additives are typically added to reduce the degradation of the metallic parts contained in the engine oil in amounts from about 0.02 to 1 wt. %. Examples include zinc dialkyldithiophosphate, phosphosulfurized hydrocarbons and the products obtained by reaction of a phosphosulfurized hydrocarbon with an alkaline earth metal oxide or hydroxide, preferably in the presence of an alkylated phenol or of an alkylphenol thioester. In one embodiment, the rust inhibitor or anticorrosion agents may be a nonionic polyoxyethylene surface active agent. Nonionic polyoxyethylene surface active agents include, but are not limited to, polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol mono-oleate, and polyethylene glycol monooleate. Rust inhibitors or anticorrosion agents may also be other compounds, which include, for example, stearic acid and other fatty acids, dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of heavy sulfonic acid, partial carboxylic acid ester of polyhydric alcohols, and phosphoric esters. In another embodiment, the rust inhibitor is a calcium stearate salt.
Detergents: In engine oil compositions, metal-containing or ash-forming detergents function both as detergents to reduce or remove deposits and as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending engine life. Detergents generally comprise a polar head with long hydrophobic tail, with the polar head comprising a metal salt of an acid organic compound.
In one embodiment, the engine oil composition contains one or more detergents, which are normally salts, e.g., overbased salts. Overbased salts, or overbased materials, are single phase, homogeneous Newtonian systems characterized by a metal content in excess of that which would be present according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. In another embodiment, the engine oil composition comprises at least a carboxylate detergent. Carboxylate detergents, e.g., salicylates, can be prepared by reacting an aromatic carboxylic acid with an appropriate metal compound such as an oxide or hydroxide. In yet another embodiment, the engine oil composition comprises at least an overbased detergent. Examples of the overbased detergents include, but are not limited to calcium sulfonates, calcium phenates, calcium salicylates, calcium stearates and mixtures thereof. Overbased detergents may be low overbased (e.g., Total Base Number (TBN) below about 50). Suitable overbased detergents may alternatively be high overbased (e.g., TBN above about 150) or medium overbased (e.g., TBN between 50 and 150). The lubricating oil compositions may comprise more than one overbased detergents, which may be all low-TBN detergents, all high-TBN detergents, or a mix of those two types. Other suitable detergents for the lubricating oil compositions include “hybrid” detergents such as, for example, phenate/salicylates, sulfonate/phenates, sulfonate/salicylates, sulfonates/phenates/salicylates, and the like. In other embodiments, the composition comprises detergents made from alkyl benzene and fuming sulfonic acid, phenates (high overbased, medium overbased, or low overbased), high overbased phenate stearates, phenolates, salicylates, phosphonates, thiophosphonates, sulfonates, carboxylates, ionic surfactants and sulfonates and the like.
Oxidation Inhibitors/Antioxidants: Oxidation inhibitors or antioxidants reduce the tendency of mineral oils to deteriorate in service, which deterioration is evidenced by the products of oxidation such as sludge, lacquer, and varnish-like deposits on metal surfaces. In one embodiment, the engine oil composition contains from about 50 ppm to about 5.00 wt. % of at least an antioxidant selected from the group of phenolic antioxidants, aminic antioxidants, or a combination thereof. In other embodiments, the amount of antioxidants is between 0.10 to 3.00 wt. %. In yet other embodiments, ranging from about 0.20 to 0.80 wt. %. An example of an antioxidant used is di-C8-diphenylamine, in an amount of about 0.05 to 2.00 wt. % of the total weight of the oil composition. Other examples of antioxidants include MoS and Mo oxide compounds.
Other examples of antioxidants include hindered phenols; alkaline earth metal salts of alkylphenolthioesters having C5 to C12 alkyl side chains; calcium nonylphenol sulphide; oil soluble phenates and sulfurized phenates; phosphosulfurized or sulfurized hydrocarbons or esters; phosphorous esters; metal thiocarbamates; oil soluble copper compounds known in the art; phenyl naphthyl amines such as phenylene diamine, phenothiazine, diphenyl amine, diarylamine; phenyl-alphanaphthylamine, 2,2′-diethyl-4,4′-dioctyl diphenylamine, 2,2′diethyl-4-t-octyldiphenylamine; alkaline earth metal salts of alkylphenol thioesters, having C5 to C12 alkyl side chains, e.g., calcium nonylphenol sulfide, barium t-octylphenol sulfide, zinc dialkylditbiophosphates, dioctylphenylamine, phenylalphanaphthylamine and mixtures thereof. Some of these antioxidants further function as corrosion inhibitors. Other suitable antioxidants which also function as antiwear agents include bis alkyl dithiothiadiazoles such as 2,5-bis-octyl dithiothiadiazole.
Anti-foamants: In one embodiment, the engine oil further comprises an anti-foamant (foam inhibitor) in amounts ranging from about 5 to about 50 ppm. Examples include alkyl methacrylate polymers, dimethyl silicone polymers, and foam inhibitors of the polysiloxane type, e.g., silicone oil and polydimethyl siloxane, for foam control. In another embodiment, the anti-foamant is a mixture of polydimethyl siloxane and fluorosilicone. In yet another embodiment, the engine oil further comprises an acrylate polymer anti-foamant, with a weight ratio of the fluorosilicone antifoamant to the acrylate anti-foamant ranging from about 3:1 to about 1:4. In a fourth embodiment, the engine oil comprises an anti-foam-effective amount of a silicon-containing anti-foamant such that the total amount of silicon in the engine oil is at least 30 ppm. In yet another embodiment, the silicon-containing antifoam agent is selected from the group consisting of fluorosilicones, polydimethylsiloxane, phenyl-methyl polysiloxane, linear siloxanes, cyclic siloxanes, branched siloxanes, silicone polymers and copolymers, organo-silicone copolymers, and mixtures thereof.
Seal swelling agents: Seal fixes are also termed seal swelling agents or seal pacifiers. They are often employed in lubricant or additive compositions to insure proper elastomer sealing, and prevent premature seal failures and leakages. In one embodiment, the composition further includes at least a seal swell agent selected from oil-soluble, saturated, aliphatic, or aromatic hydrocarbon esters such as di-2-ethylhexylphthalate, mineral oils with aliphatic alcohols such as tridecyl alcohol, triphosphite ester in combination with a hydrocarbonyl-substituted phenol, and di-2-ethylhexylsebacate.
Corrosion inhibitors (Anti-corrosive agents): These additives are typically added to reduce the degradation of the metallic parts contained in the engine oil. Examples include zinc dialkyldithiophosphate, phosphosulfurized hydrocarbons and the products obtained by reaction of a phosphosulfurized hydrocarbon with an alkaline earth metal oxide or hydroxide, preferably in the presence of an alkylated phenol or of an alkylphenol thioester. In one embodiment, the rust inhibitor or anticorrosion agents may be a nonionic polyoxyethylene surface active agent. Nonionic polyoxyethylene surface active agents include, but are not limited to, polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol mono-oleate, and polyethylene glycol monooleate. Rust inhibitors or anticorrosion agents may also be other compounds, which include, for example, stearic acid and other fatty acids, dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of heavy sulfonic acid, partial carboxylic acid ester of polyhydric alcohols, and phosphoric esters. In another embodiment, the rust inhibitor is a calcium stearate salt.
Detergents: In engine oil compositions, metal-containing or ash-forming detergents function both as detergents to reduce or remove deposits and as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending engine life. Detergents generally comprise a polar head with long hydrophobic tail, with the polar head comprising a metal salt of an acid organic compound.
In one embodiment, the engine oil composition contains one or more detergents, which are normally salts, e.g., overbased salts. Overbased salts, or overbased materials, are single phase, homogeneous Newtonian systems characterized by a metal content in excess of that which would be present according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. In another embodiment, the engine oil composition comprises at least a carboxylate detergent. Carboxylate detergents, e.g., salicylates, can be prepared by reacting an aromatic carboxylic acid with an appropriate metal compound such as an oxide or hydroxide. In yet another embodiment, the engine oil composition comprises at least an overbased detergent. Examples of the overbased detergents include, but are not limited to calcium sulfonates, calcium phenates, calcium salicylates, calcium stearates and mixtures thereof. Overbased detergents may be low overbased (e.g., Total Base Number (TBN) below about 50). Sutiable overbased detergents may alternatively be high overbased (e.g., TBN above about 150) or medium overbased (e.g., TBN between 50 and 150). The lubricating oil compositions may comprise more than one overbased detergents, which may be all low-TBN detergents, all high-TBN detergents, or a mix of those two types. Other suitable detergents for the lubricating oil compositions include “hybrid” detergents such as, for example, phenate/salicylates, sulfonate/phenates, sulfonate/salicylates, sulfonates/phenates/salicylates, and the like. In other embodiments, the composition comprises detergents made from alkyl benzene and fuming sulfonic acid, phenates (high overbased, medium overbased, or low overbased), high overbased phenate stearates, phenolates, salicylates, phosphonates, thiophosphonates, sulfonates, carboxylates, ionic surfactants and sulfonates and the like.
Oxidation Inhibitors/Antioxidants: Oxidation inhibitors or antioxidants reduce the tendency of mineral oils to deteriorate in service, which deterioration is evidenced by the products of oxidation such as sludge, lacquer, and varnish-like deposits on metal surfaces. In one embodiment, the engine oil composition contains from about 50 ppm to about 5.00 wt. % of at least an antioxidant selected from the group of phenolic antioxidants, aminic antioxidants, or a combination thereof. In other embodiments, the amount of antioxidants is between 0.10 to 3.00 wt. %. In yet other embodiments, ranging from about 0.20 to 0.80 wt. %. An example of an antioxidant used is di-C8-diphenylamine, in an amount of about 0.05 to 2.00 wt. % of the total weight of the oil composition. Other examples of antioxidants include MoS and Mo oxide compounds.
In one embodiment, the antioxidant is selected from the group of hindered phenols; alkaline earth metal salts of alkylphenolthioesters having C5 to C12 alkyl side chains; calcium nonylphenol sulphide; oil soluble phenates and sulfurized phenates; phosphosulfurized or sulfurized hydrocarbons or esters; phosphorous esters; metal thiocarbamates; oil soluble copper compounds known in the art; phenyl naphthyl amines such as phenylene diamine, phenothiazine, diphenyl amine, diarylamine; phenyl-alphanaphthylamine, 2,2′-diethyl-4,4′-dioctyl diphenylamine, 2,2′diethyl-4-t-octyldiphenylamine; alkaline earth metal salts of alkylphenol thioesters, having C5 to C12 alkyl side chains, e.g., calcium nonylphenol sulfide, barium t-octylphenol sulfide, zinc dialkylditbiophosphates, dioctylphenylamine, phenylalphanaphthylamine and mixtures thereof. Some of these antioxidants further function as corrosion inhibitors. Other suitable antioxidants which also function as antiwear agents include bis alkyl dithiothiadiazoles such as 2,5-bis-octyl dithiothiadiazole.
Anti-foamants: In one embodiment, the engine oil further comprises an anti-foamant (foam inhibitor) in amounts ranging from about 5 to about 50 ppm. Examples include alkyl methacrylate polymers, dimethyl silicone polymers, and foam inhibitors of the polysiloxane type, e.g., silicone oil and polydimethyl siloxane, for foam control. In another embodiment, the anti-foamant is a mixture of polydimethyl siloxane and fluorosilicone. In yet another embodiment, the engine oil further comprises an acrylate polymer anti-foamant, with a weight ratio of the fluorosilicone antifoamant to the acrylate anti-foamant ranging from about 3:1 to about 1:4. In a fourth embodiment, the engine oil comprises an anti-foam-effective amount of a silicon-containing anti-foamant such that the total amount of silicon in the engine oil is at least 30 ppm. In yet another embodiment, the silicon-containing antifoam agent is selected from the group consisting of fluorosilicones, polydimethylsiloxane, phenyl-methyl polysiloxane, linear siloxanes, cyclic siloxanes, branched siloxanes, silicone polymers and copolymers, organo-silicone copolymers, and mixtures thereof.
Anti-wear agents: Anti-wear agents can also be added to the engine oil composition. In one embodiment, the composition further comprises at least an anti-wear agent selected from phosphates, phosphites, carbamates, esters, sulfur containing compounds, and molybdenum complexes. Other representative of suitable antiwear agents are zinc dialkyldithiophosphate, zinc diaryldilhiophosphate, Zn or Mo dithiocarbamates, phosphites, amine phosphates, borated succinimide, magnesium sulfonate, and mixtures thereof. In one embodiment, the composition further comprises at least a dihydrocarbyl dithiophosphate metal as antiwear and antioxidant agent in amounts of about 0.1 to about 10 wt. %, The metal may be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel or copper.
Extreme Pressure Agents: In one embodiment, the engine oil composition further comprises an extreme pressure agent. Examples include alkaline earth metal borated extreme pressure agents and alkali metal borated extreme pressure agents. Other examples include sulfurized olefins, zinc dialky-1-dithiophosphate (primary alkyl, secondary alkyl, and aryl type), di-phenyl sulfide, methyl tri-chlorostearate, chlorinated naphthalene, fluoroalkylpolysiloxane, lead naphthenate, neutralized or partially neutralized phosphates, di-thiophosphates, and sulfur-free phosphates.
Some of the above-mentioned additives can provide a multiplicity of effects; thus for example, a single additive may act as a dispersant as well as an oxidation inhibitor. These multifunctional additives are well known. In one embodiment, when the engine oil composition contains one or more of the above-mentioned additives, each additive is typically blended into the base oil in an amount that enables the additive to provide its desired function. It may be desirable, although not essential, to prepare one or more additive concentrates comprising additives (concentrates sometimes being referred to as “additive packages”) whereby several additives can be added simultaneously to the oil to form the end oil composition. The final composition may employ from about 0.5 to about 30 wt. % of the concentrate, the remainder being the oil of lubricating viscosity. The components can be blended in any order and can be blended as combinations of components.
Method for Making: The Pour Point Reducing Blend Component and other additives can be blended into the base oil matrix individually or in various sub-combinations. In one embodiment, all of the components are blended concurrently as an additive concentrate, or additives plus a diluent, such as a hydrocarbon solvent. The use of an additive concentrate takes advantage of the mutual compatibility afforded by the combination of ingredients when in the form of an additive concentrate. In another embodiment, the engine oil composition is prepared by mixing the base oil and the pour point depressant with the separate additives or additive package(s) at an appropriate temperature, e.g., 60° C., until homogeneous.
Applications: Among other things, the engine oil composition resists viscosity shear and is formulated with a lower level of viscosity modifiers for excellent protection of gears, bearings, cam lobes, cam followers, and other high-pressure components in engines and transmissions.
The composition delivers lubrication in all types of automotive and commercial vehicles gasoline and diesel engines, gasoline fueled four-stroke outboard, inboard, inboard/outboard (lPO) and personal watercraft motors, including but not limited to large and small gasoline or diesel engines in cars, motorcycles, trucks, motor homes, maintenance equipment, heavy equipment, street rods, military, and marine applications.
Properties: In one embodiment, the engine oil composition is characterized as meeting at least one of International Lubricant Standardization and Approval Committee (ILSAC) GF-4, American Petroleum Institute (API) CI-4, API CJ4 performance specifications. In one embodiment, the engine oil composition meets both ILSAC GF-4 and API CI-4 specifications. In another embodiment, the engine oil composition meets or exceeds European ACEA: A1, A5, B1, B5, ACEA C1, ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1, and all ILSAC GF-4 for API Certified Gasoline Engine Oils and meets Energy Conserving Standards. In yet another embodiment, the engine oil composition meets the specifications for SAE J300 viscosity grade 0W-XX, 5W-XX, 10W-XX, 15W-XX, 20W-XX, or 25W-XX engine oil, wherein XX represents the integer 20, 30, 40, 50 or 60.
In one embodiment, the engine oil composition is characterized as meeting the requirements of SAE J300 over a wide temperature range while still having a low level of viscosity modifiers (viscosity index improvers or VII). Depending on the diluted factor of the viscosity modifiers used, this amount may range from 0.3 to 25 wt. %. In one embodiment, the reduced amount of viscosity modifiers is less than 10 wt. %.
In one embodiment, the engine oil composition has a kinematic viscosity at 100° C. as specified according to SAE J300 for the applicable grade. In one embodiment, the composition has a kinematic viscosity at 100° C. between 3.5 and 25 mm2/s. In a second embodiment, a kinematic viscosity at 100° C. between 8 and 20 mm2/s.
Viscometrics is an important lubricant parameter that governs the successful operation of engine oils. In one embodiment, the engine oil composition comprising a isomerized base oil has an apparent viscosity of 60,000 cP or less in MRV test (ASTM D4684-07@−40° C.).
In one embodiment, the engine oil composition has a cold crank simulator viscosity at −35° C. of less than 9000 cP, and less than 7500 cP in a second embodiment, and less than 6000 cP in a third embodiment. In one embodiment, the engine oil composition has a mini rotary viscosity at −30° C. of less than 60000 cP and a yield stress of less than 35 Pa (as measured per ASTM D4684-07@−30° C.).
In one embodiment, the engine oil composition is characterized as exhibiting excellent fuel economy performance, of at least 1% compared to an engine oil composition of the prior art, i.e., engine oil compositions employing non-isomerized base oils. Fuel economy performance can be measured using the Phase I Sequence VIB Screener Test, to be described in the Examples section. In another embodiment, the fuel savings is at least 1.5% compared to engine oil compositions of the prior art. In a third embodiment, the fuel savings is at least 1.75%.
The examples are given as non-limitative illustration of aspects of the invention. The compositions were subject to a number of tests including the following non-standard tests:
Phase I Sequence VIB Screener Test: This is an abbreviated test method of ASTM D6837-06 for measurement of effects of automotive engine oils on fuel economy. ASTM D6837-06, Standard Test Method for Measurement of Effects of Automotive Engine Oils on Fuel Economy of Passenger Cars and Light-Duty Trucks in Sequence VIB Spark Ignition Engine, is an engine dynamometer test that measures the ability of a lubricant to improve the fuel economy of passenger cars and light-duty trucks equipped with a low friction engine. In the abbreviated test, testing ends after Phase I and does not proceed to Phase II. As a result, the method by which % fuel economy improvement (FEI) is calculated is also slightly different.
Under ASTM D6837-06, % fuel economy improvement (FEI) is calculated using weighted results from two baseline calibration (BC) candidates, one before Phase I and one after Phase II. In the abbreviated test used herein, 100% of a single baseline candidate is used in making the % FEI calculation as described on page 9 of ASTM D6837-06, with higher % FEI values indicating improved fuel economy. Fuel economy improvement (FEI) at Stage-1,-2 and -3 depends on a friction modifier in the lubricant and FEI at Stage-4 and Stage-5 depends on viscometric properties of the lubricant.
The calculation of % FEI for each stage is as follows. First, the brake specific fuel consumption (BSFC) in kg/kW,h for each stage is calculated by the following formula: (Integrated Fuel Flow)×(9549.3)/BSFC (Integrated Load) (Integrated Speed). The BSFC data for each stage is multiplied by the nominal power and by the weight factor to arrive at kg of weighted fuel consumed for each stage. Based on total fuel consumed at Phase I (from stage 1 to 5), % FEI for each stage can be calculated as follows: ((Weighted fuel consumed for each stage in the BC before oil )−(Weighted fuel consumed for each stage in the test oil))/(total fuel consumed at Phase I by BC before oil)×100.
In the Phase I Sequence VIB Screener Test used herein, Stage-4 and Stage-5 of are run at more hydrodynamic lubricating conditions (i.e., thicker oil film), while Stage-1 and Stage-2 are run closer to boundary lubricating conditions. Under boundary conditions, fuel economy is more dependent on added friction modifiers, which is not as important for fuel economy under more hydrodynamic lubricating conditions.
Traction Coefficient Test Method: As engine oils with lower traction coefficients are desirable as they provide improved fuel economy, some of the examples were subject to the Traction Coefficient Test Method as described in US Patent Publication No. 20050241990. In this test, Traction data are obtained with an MTM Traction Measurement System from PCS Instruments, Ltd. The unit is configured with a polished 19 mm diameter ball (SAE AISI 52100 steel) angled at 220 to a flat 46 mm diameter polished disk (SAE AISI 52100 steel). Measurements are made at 40° C., 70° C., 100° C., and 120° C. The steel ball and disk are driven independently by two motors at an average rolling speed of 3 Meters/sec and a slide to roll ratio (SRR) of 40% [defined as the difference in sliding speed between the ball and disk divided by the mean speed of the ball and disk. SRR=(Speed1−Speed2)/((Speed1+Speed2)−/2)]. The load on the ball/disk is 20 Newton resulting in an estimated average contact stress of 0.546 GPa and a maximum contact stress of 0.819.
Two runs with Group-III based engine lubricating oil and three runs with Fischer-Tropsch derived base oil based engine lubricating oil were conducted. In the examples, viscosity at 100° C., High-Temperature High-Shear (HTHS) viscosity at 150° C., and Noack volatility were adjusted to the same level to eliminate any influence from these properties in the results. All oils were blended as SAE OW-20 to the same Blend Viscosity of 4.3 mm2/s at 100° C.
Unless specified otherwise, the components in the examples are as follows (and expressed as wt. % in the Tables) with the same additives/additive package being used for the examples.
FTBO base oils: are from Chevron Corporation of San Ramon, Calif. The properties of the FTBO base oils used in the examples are shown in Table 4. The oils have very low initial boiling points, excellent volatility, high Oxidator BN values, high total weight % molecules with cycloparaffinic functionality, and high ratios of mono- to multi-cycloparaffins.
Group III base stock: a commercially available base stock having a kinematic viscosity at 100° C. of 4.307 and a CCS VIS at −35° C. of 3165 mPa·s.
VII is a commercially available viscosity index improver.
PPD is a commercially available pour point depressant.
FM is a commercially available friction modifier.
Additive Package is a commercially available additive package.
An embodiment of an engine oil composition containing an isomerized base oil blend was compared with a formulation containing a group III base oil of the prior art. The results are shown in Table 1.
As shown, the engine lubricating oil containing isomerized base oil(s) of Example 2 produces significantly higher fuel economy improvement (FEI), especially in hydrodynamic lubrication condition compared to the Group-III based engine lubricating oils (Example 1), with a statistically significant p-value of Phase I Stage-4+Stage-5 FEI of 0.044. A p-value close to 0 means the data, with respect to the specific test, are not the same. A p-value <0.05 means the data are statistically different, based on a 95th percentile confidence interval criteria.
Additionally, total Phase-I FEI in Example 2 was also significantly higher than that of the prior art engine oil (statistically significant p-value of the Phase-I total FEI of 0.041). Without wishing to be bound by theory, it is believed that the slightly lower base oil Blend Viscosity of Example 2 (containing isomerized base oils), as compared to the Group-III engine oil of the prior art, may have contributed to the especially good Phase I Stage-4+Stage-5% FEI.
In these examples, friction modifiers were omitted from the formulations. The results are as indicated in Table 2.
As shown in Table 2 above, Examples 3 and 5 with compositions containing isomerized base oil(s) show fuel economy benefits relative to the prior art engine oil in Stage-4+Stage-5 of Phase I Sequence VIB Screener Tests, regardless of whether or not a friction modifier (FM) was included. With respect to these Stage-4+Stage-5 results, the difference was statistically significant both when FM was included (p-value=0.036) and when FM was not included (p-value=0.046). Additionally through the Phase I Sequence VIB Screener Test, engine oil compositions containing isomerized base oil(s) show fuel economy improvements compared to the conventional Group III based engine oils.
Engine oil compositions with and without the addition of friction modifier(s) according to Table 3 were formulated and subject to the Traction Coefficient Test Method.
Results of tests according to the Traction Coefficient Test Method are presented in
For formulations without the addition of friction modifiers,
The properties of the isomerized base oils used in the examples are presented in Table 4.
For the purpose of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained and/or the precision of an instrument for measuring the value, thus including the standard deviation of error for the device or method being employed to determine the value. The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternative are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” Furthermore, all ranges disclosed herein are inclusive of the endpoints and are independently combinable. In general, unless otherwise indicated, singular elements may be in the plural and vice versa with no loss of generality. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
It is contemplated that any aspect of the invention discussed in the context of one embodiment of the invention may be implemented or applied with respect to any other embodiment of the invention. Likewise, any composition of the invention may be the result or may be used in any method or process of the invention.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. All citations referred herein are expressly incorporated herein by reference.
This application claims benefit under 35 USC 119 of Provisional Application 60/991296 filed Nov. 30, 2007. This application claims priority to and benefits from the foregoing, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60991296 | Nov 2007 | US |
