Patent Application
20090062166
The invention relates generally to compositions suitable for use as lubricants, more particularly for use as slideway lubricants.
A slideway is a mechanical guide designed to provide a machine tool with a track surface that is stable under load (i.e., minimal deflection) with a consistent finish for constant frictional forces, regardless of the rate of movement. Machine builders have met these design goals by constructing slideways in various configurations (horizontal, vertical, angled) and fabricating them from several different materials (iron, steel or plastic). Machine tools are frequently required to manufacture articles to very fine tolerances, for example the tolerance in the manufacture of a cam shaft may be only about one micron. For this purpose, the machine tool must be accurately positioned. Slideway lubricants are used to lubricate the surface on which the machine tool is mounted to facilitate the required positioning, thus maximizing the performance of the slideway.
In typical applications, such as hydraulic field services, machine tools may come in contactwith contaminated water, which can adversely affect machining performance. Good water separation is much needed in slideway lubricant compositions. In the prior art, demulsifying additives (or demulsifiers) such as copolymers of ethylene oxide and propylene oxide are typically employed to help improve the demulsibility of a lubricant. In some of the slideway lubricants in the prior art, the demulsifiers tend not to be fully soluble, leading to troublesome precipitates which may cause clogging in the machine tools.
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, an alternative hydrocarbon product, e.g., 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 SHELLL® 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 a need for a novel slideway lubricant composition having excellent demulsibility, containing alternative hydrocarbon products.
In one aspect, the invention relates to a slideway lubricant composition comprising: a) a base oil comprising at least an isomerized base oil having consecutive numbers of carbon atoms and less than 10 wt % naphthenic carbon by n-d-M, b) 0.001 to 10 wt % at least an additive selected from an additive package, an oxidation inhibitor, a high pressure agent, a friction modifier, an adhesion additive, an anti-wear agent, a metal passivator, an anti-foam agent, a demulsifying agent, and mixtures thereof, wherein the lubricant composition contains a sufficient amount of isomerized base oil for the composition to separate from water in less than 60 minutes as measured according to ASTM D-1401-2002. In one embodiment, this sufficient amount is 95 to 99.999 wt. %.
In another aspect, the invention relates to a method for demulsifying a slideway lubricant, the method comprises adding to a base oil typically used for preparing the slideway lubricant a sufficient amount of isomerized base oil for the lubricant to separate from water in less than 60 minutes as measured according to ASTM D-1401-2002, wherein the isomerized base oil has consecutive numbers of carbon atoms and less than 10 wt % naphthenic carbon by n-d-M, and wherein the typical base oil is one of a mineral oil, an oligomer of an alphaolefin, an ester, a synthetic hydrocarbon oil, and mixtures thereof.
In yet another aspect, there is provided another method for demulsifying a slideway lubricant, the method comprises preparing a base oil comprising a sufficient amount of isomerized base oil for the lubricant to separate from water in less than 60 minutes as measured according to ASTM D-1401-2002, wherein the isomerized base oil has consecutive numbers of carbon atoms and less than 10 wt % naphthenic carbon by n-d-M.
The following terms will be used throughout the specification and will have the following meanings unless otherwise indicated.
By improved demulsibility (demulse performance) is meant the ability of an oil to separate from water. The established test to evaluate the ability of an industrial oil to separate from water is the ASTM D1401. In this test 40 mL of oil is mixed with 40 ml of water at 54° C. and the time taken for the resulting emulsion to reduce to 3 mL or less (considered to be complete separation) is recorded. If complete separation does not occur, then the volume of oil, water and emulsion present is recorded.
As used herein, “slide way” may be used interchangeably with “slide way” or “slide-way,” and “slideway lubricant” may be used interchangeably with or “slideway composition” or “slideway lubricant composition.”
“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 high 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)). 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. The steps are as follows: A) Prepare a solution of 5-10% of the test hydrocarbon in deuterochloroform. B) Acquire a normal proton spectrum of at least 12 ppm spectral width and accurately reference the chemical shift (ppm) axis, with the instrument having sufficient gain range to acquire a signal without overloading the receiver/ADC, e.g., when a 30 degree pulse is applied, the instrument having a minimum signal digitization dynamic range of 65,000. In one embodiment, the instrument has a dynamic range of at least 260,000. C) Measure the integral intensities between: 6.0-4.5 ppm (olefin); 2.2-1.9 ppm (allylic); and 1.9-0.5 ppm (saturate). D) Using the molecular weight of the test substance determined by ASTM D 2503-92 (Reapproved 2002), calculate: 1. The average molecular formula of the saturated hydrocarbons; 2. The average molecular formula of the olefins; 3. The total integral intensity (=sum of all integral intensities); 4. The integral intensity per sample hydrogen (=total integral/number of hydrogens in formula); 5. The number of olefin hydrogens (=olefin integral/integral per hydrogen); 6. The number of double bonds (=olefin hydrogen times hydrogens in olefin formula/2); and 7. The wt % olefins by proton NMR=100 times the number of double bonds times the number of hydrogens in a typical olefin molecule divided by the number of hydrogens in a typical test substance molecule. In this test, the wt % olefins by proton NMR calculation procedure, D, works particularly well when the percent olefins result is low, less than 15 wt %.
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.
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 slideway lubricant composition having excellent demulsibility comprises optional additives in a matrix of base oil or base oil blends.
Base Oil Matrix Component: In one embodiment, the base oil or blend of the slideway lubricant composition 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”).
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 10 wt % naphthenic carbon by n-d-M. 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 than50 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 Vicosity 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 AlT 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).
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% 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% naphthenic carbon. In another embodiment, a kinematic viscosity of 1.8-3.5 mm2/s at 100° C. and 2.5-4% naphthenic carbon. In a third embodiment, a kinematic viscosity of 3-6 mm2/s at 100° C. and 2.7-5% naphthenic carbon. In a fourth embodiment, a kinematic viscosity of 10-30 mm2/s at 100° C. and greater than 5.2% 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 slideway lubricant composition.
In one embodiment, the isomerized base oil is a white oil as disclosed in U.S. Pat. No. 7,214,307 and US Patent Publication US20060016724. In one embodiment, the isomerized base oil is a white oil having a kinematic viscosity between about 1.5 cSt and 36 mm2/s at 100° C., a viscosity index greater than an amount calculated by the equation: Viscosity Index=28×Ln(the Kinematic Viscosity at 100° C. )+95, between 5 and less than 18 weight percent molecules with cycloparaffinic functionality, less than 1.2 weight percent molecules with multicycloparaffinic functionality, a pour point less than 0° C. and a Saybolt color of +20 or greater.
In one embodiment, the slideway lubricant composition employs a base oil that consists of at least one or mixtures 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 a sufficient amount of at least a isomerized base oil and 5 to 95 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, with the isomerized base oil being present being in a sufficient amount for the slideway lubricant composition to still have the desired demulsibility performance, e.g. minimal time for the resulting emulsion to reduce to 3 mL or less.
Examples of the base oils (other than the isomerized base oil) 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.
In one embodiment, the base oil matrix of the slideway lubricant is a FT base oil having a kinematic viscosity at 100° C. between 3 mm2/s and 5 mm2/s; a kinematic viscosity at 40° C. between 10 mm2/s and 20 mm2/s; a viscosity index between 135 and 150; CCS VIS in the range of 1,500-3,500 mpa·s at −40° C., 1,000-2,000 mpa·s at −35° C.; pour point in the range of −20 and −30° C.; molecular weight of 400-500; density in the range of 0.805 to 0.820; paraffinic carbon in the range of 94-97%; naphthenic carbon in the range of 3-6%; Oxidator BN of 35 to 50 hours; bromine index of 18 to 28; and Noack volatility in wt. % of 10 to 20 as measured by ASTM D5800-05 Procedure B.
Additional Optional Components: The slideway lubricant composition of the invention is characterized as having excellent demulsibility and requiring little if no demulsifying agents (demulsifiers). However, in some embodiments and depending on the end-use applications, small quantities of demulsifying agents may be optionally added in an amount ranging from 0.001 to 10.0 wt.%. In one embodiment, less than 5 wt. % of at least a demulsifying agent is added. In another embodiment, the added amount is less than 1 wt. %. In a fourth embodiment, the amount of demulsifying agent present is less than 0.5 wt. %.
Non-limiting examples of demulsifying agents include but are not limited to polyoxy-alkylene alcohols, oxyalkylated alcohols, fatty acids, fatty amines, glycols, alkyl phenol-formaldehyde condensation compounds, alkyl benzene sulphonates, polyethylene oxides, polypropylene oxides, salts and esters of oil soluble acids, oxyalkylated trimethylol alkanes, oxyalkylated alkyl phenol-formaldehyde condensation products, tetra-polyoxyalkylene derivatives of ethylene diamine, mixtures of alkylaryl sulfonates, polyoxyalkylene glycols, oxyalkylated glycols, esters of oxyalkylated glycols, oxyalkylated alkylphenolic resins, and polyoxyalkylene polyols derived from ethylene oxide, propylene oxide, 1-2, and/or 2-3 butylene oxide, and mixtures thereof.
In one embodiment, the slideway lubricant may contain other additives known in the art, e.g., high pressure agents, adhesion (tacky) additives, friction modifiers, antioxidants (oxidation inhibitors), anti-wear agents, metal passivators, anti-foam agents, etc., in amounts ranging from 0.05 to 10 wt. % to improve the properties of the composition.
In one embodiment, an adhesion additive such as a synthetic polymeric adhesion additive having an average molecular weight of at least 1,000,000 is employed to help keep the lubricant composition on the bearing surface during operation of the way table. An example is “ADDCO ADDTAC™,” available from Gateway Additives of Spartanburg, S.C.
In some applications and without an extreme pressure agent, a slideway lubricant film has a higher tendency to rupture when performing under high pressures and/or temperatures. In one embodiment, an extremepressure agent may be added in an amount of about 0.05 to about 5 wt. % to the lubricant composition to prevent destructive metal-to-metal contact in lubrication of moving surfaces at high pressures and/or temperatures. Examples of extreme pressure agents include sulfurized synthetic compounds, such as sulfurized polyisobutylene, thienyl derivatives, trithiones, disulfides, trisulfides, hydrogen sulfide adducts of olefins, dimethylbenzyl tetrasulfide and tetrasulfide derivatives of C18 hydrocarbons, C18 fatty acids, and C18 fatty acid alkyl and triglyceride esters. In one embodiment, the extreme pressure agent has a molecular weight of at least about 200 to 500 g/mole and a boiling point of at least about 300° C., thus insuring that it remains in the lubricant composition and is not evaporated during use. An example is di-tertiary dodecyl trisulfide.
In one embodiment, the composition further includes at least a friction modifier in an amount of 0.1-3 wt. %, to reduce friction, stick, and chatter between the bearing surface and the way table surface. In one embodiment, the friction modifier is a borated glycerol monooleate ester. In another embodiment, the friction modifier is a polymeric synthetic ester having an average molecular weight of greater than at least about 200,000, e.g., carboxylic acid esters; esters of monocarboxylic acids and glycerol; esters of dimer acids and monohydric alcohols; esters of glycerol and monocarboxylic fatty acids; esters of monocarboxylic fatty acids and polyhydric alcohols; and esters of dicarboxylic acids and polyhydric alcohols.
In one embodiment, the composition contains at least one of the aforementioned additives in a form of an additive package formulated for slideway lubricants. Examples are additive packages from The Elco Corporation of Cleveland, Ohio.
Method for Making: Additives used in formulating the compositions can be blended into the base oil matrix individually or in various sub-combinations. In one embodiment, all of the components are blended concurrently using an additive concentrate (i.e., 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 composition is prepared by mixing the base oil and the additive(s) at an appropriate temperature, e.g., 60° C., until homogeneous.
Applications: In one embodiment, the composition is used as a slideway lubricant for lubricating machine tool ways, flat bearings, slides and guides, e.g., lubricating the moving track of a machine tool. Its main functions are wear and corrosion protection, as well as reducing the static and dynamic friction between the machine tool and the base. It can be used on all horizontal and vertical slideways where a high quality demulsifying lubricant is required for slideway protection and with extended service life.
In one embodiment, the composition is particularly suitable for use in grinding processes, eliminating judder and protecting slideways from wear and corrosion. In another embodiment, the composition is used in applications requiring a combination of slideway and hydraulic fluid performance.
Properties: The slideway lubricant composition of the invention is characterized as having excellent demulsibility requiring little if no demulsifying additive. In one embodiment, the slideway lubricant composition contains a sufficient amount of isomerized base oil for the composition to exhibit excellent demulsibility with time to complete separation (i.e., to 3 mL or less) of less than 60 minutes as measured according to ASTM D-1401-2002 at 54° C. In a second embodiment, the slideway lubricant of the invention exhibits complete separation in less than 45 minutes at 54° C. In a third embodiment, the time to complete separation is less than 30 minutes at 54° C. In a fourth embodiment, the time to complete separation is less than 15 minutes at 54° C.
In one embodiment, the slideway lubricant composition contains a sufficient amount of isomerized base oil for the composition to exhibit excellent demulsibility with time to complete separation (i.e., to 3 mL or less) of less than 60 minutes as measured according to ASTM D-1401-2002 at 82° C. for oils with kinematic viscosities at 40° C. greater than 90 cSt. In a second embodiment, the slideway lubricant of the invention exhibits complete separation in less than 45 minutes at 82° C. for oils with kinematic viscosities at 40° C. greater than 90 cSt. In a third embodiment, the time to complete separation is less than 30 minutes at 82° C. for oils with kinematic viscosities at 40° C. greater than 90 cSt. In a fourth embodiment, the time to complete separation is less than 15 minutes at 82° C. for oils with kinematic viscosities at 40° C. greater than 90 cSt.
In one embodiment, a slideway lubricant composition having a base oil matrix consisting essentially of an isomerized base oil such as a Fischer-Tropsch derived base oil made from a waxy feed is characterized as having a very desirable low level of sulphur of less than 1 ppm, thus will not contribute to bacterial growth and odor formation.
In one embodiment, the composition meets machine tool and pneumatic tool builders, including but not limited to Cincinnati Milacron Specifications of P47, P50 and P53 for Grades 68, 220 and 32
In one embodiment, a slideway lubricant composition having a base oil matrix consisting essentially of an isomerized base oil such as a Fischer-Tropsch derived base oil shows OECD 301D levels ranging from inherently biodegradable of >30% to readily biodegradable of >90%. In one embodiment, a slideway lubricant composition with a base oil matrix having a kinematic viscosity at 40° C. of <100 mm2/s (H) exhibits an OECD 301D biodegrability of about 30%. In a second embodiment, the composition with a base oil matrix having a kinematic viscosity at 40° C. of <40 mm2/S (M) shows an OECD 301D biodegrability of about 40%. In a third embodiment, the composition with a base oil matrix having a kinematic viscosity at 40° C. of <8 mm2/s (L) shows an OECD 301D biodegrability of >=40%. In a fourth embodiment, the composition with a base oil matrix having a kinematic viscosity at 40° C. of <11 mm2/S shows an OECD 301D biodegrability of about 80%. In a fifth embodiment, the composition with a base oil matrix having a kinematic viscosity at 40° C. of <6 mm2/S shows an OECD 301D biodegrability of >93%.
In one embodiment, the slideway lubricant composition has a kinematic viscosity at 40° C. ranging from 10 to 250 mm2/s, a kinematic viscosity at 100° C. ranging from 6 to 20 mm2/s, a viscosity index ranging from 145 to 160, a COC flash point of at least 200° C., a pour point in the range of −5 to −30° C.
The following Examples are given as non-limitative illustrations of aspects of the invention. Unless specified otherwise, the components in the examples are as follows (and expressed in wt. % in Table 1):
MGTL and HGTL are FTBO base oils from Chevron Corporation of San Ramon, Calif. The properties of the FTBO base oils used in the examples are shown in Table 2.
Ergon™ Hygold 100 and Ergon™ L2000 Pale Oil are severely hydrotreated heavy napthenic distillate (Group V) from Ergon Refining, Inc.
Citgo™ 325N and Citgo™ 650N are highly refined solvent neutral oils from Citgo Petroleum Corporation, Tulsa, Okla.
Star™ 6 and Star™ 12 are Group II base oils from Shell Lubricants.
SynFuid™ 8 cSt and SynFluid™ 40 cST are polyalphaolefin (PAO) oils from Chevron Corp.
Additive X is an inactive sulfurized fatty ester and extreme pressure lubricity additive commercially available from various sources.
The data in Table 1 establishes that Example 5, showing an embodiment of the slideway lubricant composition of the invention, exhibit superior water performance separation property (measured according to ASTM D-1401-2002) compared to the compositions of Examples 1-4 which contain the base oils of the prior art.
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.
