Patent Application
20080026970
In a third embodiment a method for blending a novel formulation is also disclosed. The method comprises obtaining at least one base stock and at least one thickener, blending the base stock(s) and the thickener wherein the treat rates of the base stock(s) and thickener are chosen to achieve a favorable air release property using a relationship between the thickener, lubricant viscosity, and viscosity of the base stock(s).
We have discovered a novel combination of base stocks and additives that provide unexpected favorable improvements in air release properties. In general, the higher a fluid viscosity, the slower the air release. We have discovered, an unexpected air release benefit of using high viscosity polymers such as Polymethacrylate (“PMA”) or Polyisobutene (“PIB”) to achieve base oil viscosity with favorable air release versus prior art base oil blending. In one embodiment, this discovery enables formulating high performance industrial fluids that meet required Original Equipment Manufacturer (“OEM”) specifications while achieving optimum fluid life and extended equipment life.
In one embodiment, the lubricants are blended wherein treat rates or amounts of the thickener and additives are chosen to achieve a favorable air release property by using a qualitative relationship between the thickener, lubricant viscosity and viscosity of at least one base stock. The statistical analysis can be performed with many different commercially available software programs that are commonly used in the industry. One suitable software program is Stat-Ease Design Expert 6.01. The steps for using this software are explained in more detail in the examples.
In another embodiment, the relationship is quantitatively determined through the use of statistical analysis of air release data for a defined system of base stock(s), thickener, and lubricant viscosity. The resultant relationship or model is then applied to optimize the air release performance.
The air release performance of base stocks follows the pattern of light viscosities are better than heavy viscosities which are better than ultra heavy viscosity components. In others words, light viscosities exhibit the best performance whereas the ultra heavy viscosity components exhibit the worst air release properties.
In a preferred embodiment, the use of thickener can be utilized to achieve a target viscosity. The use of thickeners permits the heavier and poorer air release performance base stocks components to be reduced or eliminated while maintaining necessary viscosity grades.
Suitable light neutral base stocks include but are not limited to 100-150 neutral Group I, II, III, IV, V and light viscosity Gas to Liquid (“GTL”). Suitable heavy neutrals include but are not limited to 500-600 neutral Group I, II, III, IV, V and heavy viscosity GTL such as, GTL 15. In addition, ultra heavy components are typically classified as >2500SUS including Group I (Bright Stock and Cylinder Stock), IV, and V. Table 1 is included below for general reference, as the industry standard methods of viscosity reporting vary by API Group. Group I and II are generally referred to in SUS, Groups III & IV are reported in cSt (mm/s2) at 100° C., and finished lubricant viscosities are reported in cSt at 40° C.
For purposes of this invention, thickeners shall include both traditional thickeners and viscosity index improvers (“VII”). Traditional thickeners include but are not limited to PIB and high viscosity PAO. A new type of Metallocene catalyzed PAO provides a tight molecular weight distribution at higher viscosities and could be used both as a thickener and base stock in this invention. Thickeners that are Viscosity Index improvers include but are not limited to PMA, olefin co-polymer (“OCP”), styrene butadiene copolymers, styrene isoprene polymers, and SV Star polymers. The SV star polymers consist of a core (divinyl benzene) with arms of isoprene that radiate out from the core. Commercial molecules include SV200 (4 SSI), SV250 (13 SSI), SV260 (25 SSI), SV270, SV300 (59 SSI). In progressing from SV200 to SV300, the length of the isoprene arms increases. As the arm length increases, the molecular weight of the molecule increases, the thickening efficiency increase, and the shear stability decreases. The impact on shear stability is reflected by the parameter “SSI”. The higher the SSI value, the greater the viscosity loss in the industry shearing test ASTM D6578.
Table 2 demonstrates the impact Polymethacrylate has on hydraulic oil air release. As shown in table 2, the PMA containing formulations exhibit dramatically reduced air release times. The use of PMA as a viscosity modifier enables the blending of lower amount of pour point depressant and permits the use of higher percentage of lighter neutral Group I base stocks to achieve the is desired viscosity grades. In the comparative examples given in Table 1 the use of PMA enables higher amounts of 150 neutral Group I base stocks and thus decreases the amount of 600 neutral group I base stocks. This provides for better air release properties at the desired viscosities.
Table 3 demonstrates the impact of PIB on paper machine oil air release. As shown in Table 3, the higher PIB concentrations exhibit reduced air release times. The use of PIB as a thickener permits the blending of higher percentage of lighter 600 neutral Group I base stocks to achieve the desired viscosity grades. In the comparative examples given in Table 3 the use of PIB enables higher amounts of 600 neutral Group I base stocks and thus decreases the amount of bright stock. This provides for better air release properties at the desired viscosities.
In one embodiment thickener fluids are used to achieve the desired air release properties and final viscosity grades. The improvement of air release is a quadratic relationship as described by the following:
Air1 min=c−c1*A+c2*B+c3*A2−c4*B2+c5*AB Eq. 1
c terms are constants that will vary based upon type of thickener, type of heavy neutral and co-blending stock, and finished blend viscosity range.
In this situation, the viscosity of the finished fluid is fixed and the other variables implied by the values of A and B include co-blending stock amounts and thickener molecular weights.
To create a set of constants for this equation, a set of blends must be designed to cover the design spectrum for a desired viscosity grade and system of basestock(s) and thickener. The A and B values and the resultant air release data can be statistically analyzed to determine the specifics of the model and the constants appropriate for that system.
The quadratic relationship indicates there is a defined range where an air release benefit will occur due to replacing the heavier blending components with a thickener. However, the thickeners are not completely neutral towards air release performance and a performance deficit will occur if taken too far for a given set of variables. See the example 1 below for more detail on this relationship.
In a second embodiment the thickener is a viscosity index improver. In this embodiment, improvement of air release is a linear relationship as described by the following relationship:
T
0.1%
=−c+c
1
*A+c
2
*B+c
3
*C−c
4
*D Eq. 2
The variables that are not in the model but are implied by the other terms are viscosity index improver, molecular weight, and amount of co-blending stock. The linear relationship indicates that an air release benefit will continue to accrue as more viscosity index improvers are used to reduce the ratio of heavier to lighter stocks in the blend. See example 2 for detail.
Groups I, II, III, IV and V are broad categories of base oil stocks developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org) to create guidelines for lubricant base oils. Group I base stocks generally have a viscosity index of between about 80 to 120 and contain greater than about 0.03% sulfur and/or less than about 90% saturates. Group II base stocks generally have a viscosity index of between about 80 to 120, and contain less than or equal to about 0.03% sulfur and greater than or equal to about 90% saturates. Group III stock generally has a viscosity index greater than about 120 and contains less than or equal to about 0.03% sulfur and greater than about 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base stocks include base stocks not included in Groups I-IV. Table 4 summarizes properties of each of these five groups.
In a preferred embodiment, the base stocks include at least one base stock of synthetic oils and most preferably include at least one base stock of API group IV Poly Alpha Olefins. Synthetic oil for purposes of this application shall include all oils that are not naturally occurring mineral oils. Naturally occurring mineral oils are often referred to as API Group I oils.
Gas to liquid (GTL) base stocks can also be preferentially used with the components of this invention as a portion or all of the base stocks used to formulate the finished lubricant. We have discovered, favorable improvement when the components of this invention are added to lubricating systems comprising primarily Group II, Group III and/or GTL base stocks compared to lesser quantities of alternate fluids.
GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, and/or degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds, and/or elements as feedstocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and base oils are GTL materials of lubricating viscosity that are generally derived from hydrocarbons, for example waxy synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feedstocks. GTL base stock(s) include oils boiling in the lube oil boiling range separated/fractionated from GTL materials such as by, for example, distillation or thermal diffusion, and subsequently subjected to well-known catalytic or solvent dewaxing processes to produce lube oils of reduced/low pour point; wax isomerates, comprising, for example, hydroisomerized or isodewaxed synthesized hydrocarbons; hydro-isomerized or isodewaxed Fischer-Tropsch (“F-T”) material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates); preferably hydroisomerized or isodewaxed F-T hydrocarbons or hydroisomerized or isodewaxed F-T waxes, hydroisomerized or isodewaxed synthesized waxes, or mixtures thereof.
GTL base stock(s) derived from GTL materials, especially, hydroisomerized/isodewaxed F-T material derived base stock(s), and other hydroisomerized/isodewaxed wax derived base stock(s) are characterized typically as having kinematic viscosities at 100° C. of from about 2 mm2/s to about 50 mm2/s, preferably from about 3 mm2/s to about 50 mm2/s, more preferably from about 3.5 mm2/S to about 30 mm2/s, as exemplified by a GTL base stock derived by the isodewaxing of F-T wax, which has a kinematic viscosity of about 4 mm2/s at 100° C. and a viscosity index of about 130 or greater. The term GTL base oil/base stock and/or wax isomerate base oil/base stock as used herein and in the claims is to be understood as embracing individual fractions of GTL base stock/base oil or wax isomerate base stock/base oil as recovered in the production process, mixtures of two or more GTL base stocks/base oil fractions and/or wax isomerate base stocks/base oil fractions, as well as mixtures of one or two or more low viscosity GTL base stock(s)/base oil fraction(s) and/or wax isomerate base stock(s)/base oil fraction(s) with one, two or more high viscosity GTL base stock(s)/base oil fraction(s) and/or wax isomerate base stock(s)/base oil fraction(s) to produce a bi-modal blend wherein the blend exhibits a viscosity within the aforesaid recited range. Reference herein to Kinematic Viscosity refers to a measurement made by ASTM method D445.
GTL base stocks and base oils derived from GTL materials, especially hydroisomerized/isodewaxed F-T material derived base stock(s), and other hydroisomerized/isodewaxed wax-derived base stock(s), such as wax hydroisomerates/isodewaxates, which can be used as base stock components of this invention are further characterized typically as having pour points of about −5° C. or lower, preferably about −10° C. or lower, more preferably about −15° C. or lower, still more preferably about −20° C. or lower, and under some conditions may have advantageous pour points of about −25° C. or lower, with useful pour points of about −30° C. to about −40° C. or lower. If necessary, a separate dewaxing step may be practiced to achieve the desired pour point. References herein to pour point refer to measurement made by ASTM D97 and similar automated versions.
The GTL base stock(s) derived from GTL materials, especially hydroisomerized/isodewaxed F-T material derived base stock(s), and other hydroisomerized/isodewaxed wax-derived base stock(s) which are base stock components which can be used in this invention are also characterized typically as having viscosity indices of 80 or greater, preferably 100 or greater, and more preferably 120 or greater. Additionally, in certain particular instances, viscosity index of these base stocks may be preferably 130 or greater, more preferably 135 or greater, and even more preferably 140 or greater. For example, GTL base stock(s) that derive from GTL materials preferably F-T materials especially F-T wax generally have a viscosity index of 130 or greater. References herein to viscosity index refer to ASTM method D2270.
In addition, the GTL base stock(s) are typically highly paraffinic of greater than 90 percent saturates) and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stocks and base oils typically have very low sulfur and nitrogen content, generally containing less than about 10 ppm, and more typically less than about 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock and base oil obtained by the hydroisomerization/isodewaxing of F-T material, especially F-T wax is essentially nil.
In a preferred embodiment, the GTL base stock(s) comprises paraffinic materials that consist predominantly of non-cyclic isoparaffins and only minor amounts of cycloparaffins. These GTL base stock(s) typically comprise paraffinic materials that consist of greater than 60 wt % non-cyclic isoparaffins, preferably greater than 80 wt % non-cyclic isoparaffins, more preferably greater than 85 wt % non-cyclic isoparaffins, and most preferably greater than 90 wt % non-cyclic isoparaffins.
Useful compositions of GTL base stock(s), hydroisomerized or isodewaxed F-T material derived base stock(s), and wax-derived hydroisomerized/isodewaxed base stock(s), such as wax isomerates/isodewaxates, are recited in U.S. Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for example.
The additives include various commercially available industrial oil components and packages, which may include antiwear, antioxidant, defoamant, demulsifier, detergent, dispersant, metal passivation, and rust inhibition additive chemistries to deliver desired performance.
The preferred ashless antioxidants are hindered phenols and arylamines. Typical examples are butylated/octylated/styrenated/nonylated/dodecylated diphenylamines, 4,4′-methylene bis-(2,6-di-tert-butylphenol), 2,6-di-tert-butyl-p-cresol, octylated phenyl-alpha-naphthylamine, alkyl ester of 3,5-di-tert-butyl-4-hydroxy-phenyl propionic acid, and many others. Sulfur-containing antioxidants, such as sulfur linked hindered phenols and thiol esters can also be used.
Suitable dispersants include borated and non-borated succinimides, succinic acid-esters and amides, alkylphenol-polyamine coupled Mannich adducts, other related components and any combination thereof. In some embodiments, it can often be advantageous to use mixtures of such above described dispersants and other related dispersants. Examples include additives that are borated, those that are primarily of higher molecular weight, those that consist of primarily mono-succinimide, bis-succinimide, or mixtures of above, those made with different amines, those that are end-capped, dispersants wherein the back-bone is derived from polymerization of branched olefins such as polyisobutylene or from polymers such as other polyolefins other than polyisobutylene, such as ethylene, propylene, butene, similar dispersants and any combination thereof. The averaged molecular weight of the hydrocarbon backbone of most dispersants, including polyisobutylene, is in the range from 1000 to 6000, preferably from 1500 to 3000 and most preferably around 2200.
Suitable detergents include but are not limited to calcium phenates, calcium sulfonates, calcium salicylates, magnesium phenates, magnesium sulfonates, magnesium salicylates, metal carbonates, related components including borated detergents, and any combination thereof. The detergents can be neutral, mildly overbased, or highly overbased. The amount of detergents usually contributes a total base number (TBN) in a range from 1 to 9 for the formulated lubricant composition. Metal detergents have been chosen from alkali or alkaline earth calcium or magnesium phenates, sulfonates, salicylates, carbonates and similar components.
Inhibitors and antirust additives may be used as needed. Seal swell control components and defoamants may be used with the mixtures of this invention. Suitable defoamants include polydimethyl siloxane and polymacrylates.
Various antiwear and/or friction modifiers may also be utilized. Examples include but are not limited to alkylated dithiocarbamates, alkyl phosphate esters, aryl phosphate esters, thiophosphates, amine phosphates, and dithiophosphates, alkylated phosphonate esters, aliphatic succinimides, molybdenum compounds, acid amides, and any combination thereof.
Two embodiment examples were blended and tested for air release using ASTM D3427. These examples were tested at 50° C. for viscosity grades less than ISO viscosity grade 100 and 75° C. for viscosity grades greater than ISO viscosity grade 100.
The statistical analysis used in these examples can be completed with many commercially available software programs. In these examples the modeling was completed using Stat-Ease Design Expert 6.01. Below are some example steps for using Stat-Ease Design expert.
First a central composite design was selected with the number of numerical factors and the number of response factors which in both examples was 1—air release property. For the paper machine oil example the number of numerical factors was two and the hydraulic oil example had 4. Second, the data was inputted into the software in the appropriate columns. Third, the design status and evaluation are viewed to determine the recommended model. If optimizing for a new set of data, it is preferable to add or subtract numerical factors to obtain the best model F-value and R squared. Fourth, a model analysis was completed to determine if any transforms are recommended, view the analysis of the fit summary, complete ANOVA (analysis of variance), and view model diagnostics (Normal plot of residuals, residuals vs. predicted, residuals versus factor, outliers, cook's distance, leverage, predicted versus actuals, and box-cox plot for power transforms). Finally, upon finding the most suitable statistical model for the given experiment, the equation and constants are taken from ANOVA “Final equation in terms of actual factors”.
Example 1 is an ISO VG 220 viscosity grade oil comprised of varying concentrations of 150 neutral Group I base stock, 600 neutral Group I base stock, Bright Stock, Polyisobutylene polymers of varying molecular weight, and a commercially available industrial additive package comprising antiwear, dispersant, rust inhibitor, demulsifier, and antifoamant. The 10 blends were made to cover both extremes of the design spectrum with the base case being no PIB and nearly 50% bright stock to 15% of the high molecular weight (“MW”) PIB with bright stock backed completely out and target viscosity achieved by comprising the balance of basestocks from 150 and 600 neutral.
D3427 data was collected on all blends and input into a statistical analysis software package. A quadratic fit model is the preferred model shown by data analysis. The model F-value is 5.47, suggesting a 10% chance this value would occur due to noise. This model yields the algorithm shown as Eq. 3.
Air1 min=14.52639−0.33437*A+0.084938*B+2.42097E−003*A2−6.62022E−003*B2+1.26802E−003*AB Eq. 3
PIB molecular weight and bright stock treat were not factors included in the model, as they are directly tied to 600 neutral treat rate and PIB treat levels to achieve an ISO 220 viscosity grade.
In example 2, an ISO VG 68 lubricant was blended comprised of varying concentrations of 150 neutral, 600 neutral, Polymethacrylate VI improvers of varying molecular weights (expressed in terms of their viscosity (cSt at 100° C.) in the table below, and a commercially available hydraulic additive oil package.
Air release data was collected and input into a statistical analysis software package. A linear fit model is suggested by data analysis. Model F-value=15.46, showing the model is significant, with <0.01% chance that a Model F-value this large could occur due to noise. This linear fit model algorithm is represented by Eq. 4.
T
0.1%=−0.084609+4.93216E−003*VI+0.067041*KV40+0.031392*600N−0.032042*PMA Treat Eq. 4
There were 4 data points used in this statistical analysis that were not in the range of 66-68.5 cST@ 40° C. Since viscosity is extremely important to air release at the lower viscosity grades, the analysis used cST@40° C. as one of the factors. In this embodiment, as more data points of cST@40° C. of 66-68.5 are added into the model, the cST@40° C. factor can be considered constant and removed from the analysis. Polymer molecular weight was run in the model but has very low impact, suggesting the implications of that term are already accounted for in the percent of 600 neutral Group II and viscosity index modifiers results that are in the model already.
Diagnostics of the model show there are no problems with data analysis.
This application claims benefit of U.S. Ser. No. 60/833,870 filed Jul. 28, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60833870 | Jul 2006 | US |
