Patent Application
20140274827
The present invention relates to the field of lubricant base stocks. It more particularly relates to lubricant base stocks with improved filterability. Still more particularly, the present disclosure relates to lubricant base stocks including bright stock with a heavy neutral as an additive for improved filterability.
Lubricant base stocks are commonly used for the production of lubricants, such as lubricating oils for automotives, industrial lubricants and lubricating greases. A base oil is defined as a combination of two or more base stocks used to make a lubricant composition. They are also used as process oils, white oils, metal working oils and heat transfer fluids. Finished lubricants consist of two general components, lubricating base stock and additives. Lubricating base stock is the major constituent in these finished lubricants and contributes significantly to the properties of the finished lubricant. In general, a few lubricating base stocks are used to manufacture a wide variety of finished lubricants by varying the mixtures of individual lubricating base stocks and individual additives.
According to the American Petroleum institute (API) classifications, base stocks are categorized in five groups based on their saturated hydrocarbon content, sulfur level, and viscosity index (Table 1). Lube base stocks are typically produced in large scale from non-renewable petroleum sources. Group I, II, and III base stocks are all derived from crude oil via extensive processing, such as solvent extraction, solvent or catalytic dewaxing, and hydroisomerization. Group III base stocks can also be produced from synthetic hydrocarbon liquids obtained from natural gas, coal or other fossil resources. Group IV base stocks, the polyalphaolefins (PAO), are produced by oligomerization of alpha olefins, such as 1-decene. Group V base stocks include everything that does not belong to Groups I-IV, such as naphthenics, polyalkylene glycols (PAG), and esters.
The automotive industry has been using lubricants and thus base stocks with improved technical properties for a long time. Increasingly, the specifications for finished lubricants require products with excellent low temperature properties, high oxidation stability, low filterability and low volatility. Generally lubricating base stocks are base stocks having kinematic viscosity of about 3 cSt or greater at 100° C. (Kv100); pour point (PP) of about −12° C. or less; and viscosity index (VI) about 90 or greater. In general, high performance lubricating base stocks should have a Noack volatility no greater than current conventional Group I or Group II light neutral oils. Currently, only a small fraction of the base stocks manufactured today are able to meet these demanding specifications.
U.S. Patent Publication No. 2006/0019841 A1 discloses the use of a C12-20 polyalkyl methacrylate polymer as a lubricating oil additive such that the C12-20 polyalkyl methacrylate polymer accounts for 0.1 to 0.3% by weight of the finished lubricating oil. The use comprises the addition of said C12-20 polyalkyl methacrylate polymer to a lubricating oil based on mineral oil to improve the filtration of said lubricating oil based on mineral oil.
Group I base stocks may be further broken down based on kinematic viscosity range at 100 deg. C. into light neutral (LN), heavy neutral (RN) and bright stock (BS). Light neutral has a kinematic viscosity in the range of 4-6 cSt, heavy neutral (HN) has a kinematic viscosity in the range of 12 cSt, and bright stock has a kinematic viscosity in the range of 30-34 cSt. Due to its high viscosity, bright stock is used in many industrial oil applications. In many of these applications, cleanliness of the lubricating oil is an important property because the oil may pass through fine orifices and filters. The lubricating oil needs to have acceptable filterability to keep fine orifices and filters from plugging up during operation. Bright stock is produced commercially with a wide range of filterabilities. Bright stock presents challenges for filterability because of its relatively high viscosity. In addition, filterability becomes more of an issue as bright stock is produced from more challenged crudes.
Hence, there is a need to improve the filterability of bright stock to increase the range of crude oils that it may be produced from and the lubricating oil applications that it may be used in.
According to the present disclosure, an advantageous lubricant base stock comprises a bright stock and an effective amount of a heavy neutral, wherein the filterability of the base stock as measured by the Membrane Filtration Method is less than or equal to 400 seconds.
A further aspect of the present disclosure relates to an advantageous lubricating oil comprising a lubricant base stock and an effective amount of one or more lubricant additives, wherein the base stock includes a bright stock and an effective amount of a heavy neutral, wherein the filterability of the base stock as measured by the Membrane Filtration Method is less than or equal to 400 seconds.
Another aspect of the present disclosure relates to an advantageous method of improving the filterability of a lubricant base stock comprising providing a bright stock and a heavy neutral, and adding an effective amount of the heavy neutral to the bright stock, wherein the filterability of the base stock as measured by the Membrane Filtration Method is less than or equal to 400 seconds.
These and other features and attributes of the disclosed lubricant base stocks, lubricating oils and methods of improving filterability of the present disclosure and their advantageous applications and/or uses will be apparent from the detailed description which follows, particularly when read in conjunction with the figures appended hereto.
To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, wherein:
All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.
The present disclosure provides novel lubricant base stocks with improved filterability. The Applicants have unexpectedly and surprisingly discovered that when a small amount of heavy neutral (HN) Group I base stock is added bright stock, there is step change improvement in filterability. This permits bright stock to be used in a broader range of filterability requiring lubricant formulations.
Refineries do not manufacture a single lube base stock but rather process several distillate fractions and a vacuum residuum fraction. Generally, at least three distillate fractions differing in boiling range and the residuum may be refined. These four fractions have acquired various names in the refining art, the most volatile distillate fraction often being referred to as the “light neutral” fraction or oil. The other distillates are called “intermediate neutral” and “heavy neutral” oils. The vacuum residuum, after deasphalting, solvent extraction and dewaxing, is commonly referred to as “bright stock.” Thus, the manufacture of lubricant base stocks involves a process for producing a slate of base stocks, which slate includes at least one refined distillate and one bright stock. Additionally, each subtractive step produces a byproduct which may be processed further or sold to an industry which has developed a use for the byproduct.
The starting point for producing mineral oil lubricants is in the atmospheric or vacuum distillation tower. Distillation separates the crude oil into different components by their boiling range. The lubricant boiling range fraction, which boils above about 650 degree. F, makes the charge stock for lubricant refining. The components of the lubricant charge stock include paraffins, naphthenes, aromatics, resins and asphaltenes. The paraffinic and naphthenic distillate fractions are generally referred to as the neutrals, e.g. heavy neutral and light neutral. Although the heavy neutral is characterized by a higher percentage of naphthenes and the light neutral is characterized by a higher percentage paraffins, both contain some aromatics along with some paraffins and naphthenes. Because the aromatic components lead to high viscosity and extremely poor viscosity indices, highly aromatic asphaltic type crudes are not the preferred feedstocks. The resins and alphaltenes are undesirable because they are too viscous and contain high levels of metals and sulfur. The paraffinic and naphthenic crude stocks are preferred yet their lubricant qualities conflict. The more paraffinic stocks make good lubricants because they possess excellent viscosity properties, yet the long straight chain paraffinic component encourages an undesirably high pour point. On the other hand, the naphthenic stocks have the desirable low pour point but have poor viscosity properties.
Bright stock constitutes a bottoms fraction which has been highly refined and dewaxed. Bright stock is a high viscosity base oil. Conventional petroleum derived bright stock is named for the SUS viscosity at 210 degrees F., having viscosities above 180 cSt at 40 degrees C., preferably above 250 cSt at 40 degrees C., and more preferably ranging from 500 to 1100 cSt at 40 degrees C. Alternatively, bright stock has a kinematic viscosity in the range of 30-34 cSt at 100 degrees C. Bright stock may be an API Group I or Group II base stock depending on its properties. U.S. Pat. No. 7,776,206 entitled “Production of High Quality Lubricant Bright Stock” discloses a process for producing bright stock from a heavy feed petroleum crude, and is herein incorporated by reference in its entirety. Group I heavy neutral base stock heavy neutral (HN) has a kinematic viscosity in the range of 10-12 cSt.
In one embodiment, disclosed is a lubricant base stock including a bright stock that incurs a step change improvement in filterability as measured by the Membrane Filtration Method for determining sediment and filterability of industrial oils (ExxonMobil Analytical Test Method 1082-01) when an effective amount of a heavy neutral is added to the lubricant base stock. An effective amount of a Group I heavy neutral is defined as ranging from 0.5 to 50 wt. % of the base stock, or from 0.75 to 20 wt. % of the base stock, or from 1.0 to 20 wt. % of the base stock. At these levels of heavy neutral in the bright stock, the filterability of the base stock as measured by the Membrane Filtration Method is less than or equal to 400 seconds, or less than or equal to 300 seconds, or less than or equal to 200 seconds. The Applicants have also discovered that the filterability of the bright stock including the effective amount of heavy neutral is particularly stable when stored at room temperature. That is, the filterability increases less than 200 seconds over a time frame of 4-weeks when stored at room temperature, or less than 150 seconds over a time frame of 4-weeks when stored at room temperature, or less than 100 seconds over a time frame of 4-weeks when stored at room temperature, or less than 50 seconds over a time frame of 4-weeks when stored at room temperature.
After blending the heavy neutral into the bright stock, the base stock may have a kinematic viscosity at 100° C. ranging from 10 to 40 cSt, or from 10 to 34 cSt, or from 10 to 30 cSt, or from 10 to 20 cSt, or from 10 to 18 cSt, or from 10 to 12 cSt.
In another embodiment, disclosed is a method of improving the filterability of a lubricant base stock for bright stock by incorporating into the base stock an effective amount of heavy neutral. The filterability as measured by the Membrane Filtration Method for determining sediment and filterability of industrial oils (ExxonMobil Analytical Test Method 1082-01) is significantly reduced compared to a bright stock that does not include the HN. An effective amount of a Group I heavy neutral is defined as ranging from 0.5 to 50 wt. % of the base stock, or from 0.75 to 20 wt. % of the base stock, or from 1.0 to 20 wt.% of the base stock. At these levels of the heavy neutral in the bright stock, the filterability of the base stock as measured by the Membrane Filtration Method is less than or equal to 400 seconds, or less than or equal to 300 seconds, or less than or equal to 200 seconds. The Applicants have also discovered that the filterability of the bright stock including the effective amount of HN is particularly stable when stored at room temperature. That is, the filterability increases less than 200 seconds over a time frame of 4-weeks when stored at room temperature, or less than 150 seconds over a time frame of 4-weeks when stored at room temperature, or less than 100 seconds over a time frame of 4-weeks when stored at room temperature, or less than 50 seconds over a time frame of 4-weeks when stored at room temperature,
In yet another embodiment, disclosed is a lubricating oil including a lubricant base stock and lubricant additives that also incurs a step change improvement in filterability as measured by the Membrane Filtration Method for determining sediment and filterability of industrial oils (ExxonMobil Analytical Test Method 1082-01) when a bright stock with an effective amount of a heavy neutral is added to the lubricating oil. Hence, the benefits in filterability obtained in the bright stock and FIN combination are retained when other additives as added to make a lubricating oil. An effective amount of a heavy neutral in the lubricating oil is defined as ranging from 0.5 to 50 wt. % of the base stock, or from 0.75 to 20 wt. % of the base stock, or from 1.0 to 20 wt. % of the base stock. At these levels of the heavy neutral in the bright stock, the filterability of the base stock as measured by the Membrane Filtration Method is less than or equal to 400 seconds, or less than or equal to 300 seconds, or less than or equal to 200 seconds. The Applicants have also discovered that the filterability of the bright stock including the effective amount of HN is particularly stable when stored at room temperature. That is, the filterability increases less than 200 seconds over a time frame of 4-weeks when stored at room temperature, or less than 150 seconds over a time frame of 4-weeks when stored at room temperature, or less than 100 seconds over a time frame of 4-weeks when stored at room temperature, or less than 50 seconds over a time frame of 4-weeks when stored at room temperature.
The one or more lubricant additives that may be added to the lubricating oil may include, but is not limited to, antioxidants, stabilizers, detergents, dispersants, demulsifiers, antioxidants, anti-wear additives, viscosity index modifiers, pour point depressants, friction modifiers, anti-foam additives, defoaming agents, corrosion inhibitors, wetting agents, rust inhibitors, copper passivators, metal deactivators, extreme pressure additives, and combinations thereof. The effective amount of the one or more lubricant additives in the lubricating oil is defined as ranging from 0.2 to 20 wt. % of the lubricating oil, or from 0.4 to 18 wt. % of the lubricating oil, or from 1.0 to 15 wt. % of the lubricating oil, or from 2.0 to 10 wt. % of the lubricating oil, or from 4.0 to 8 wt. % of the lubricating oil.
The lube base stocks with improved filterability of the present disclosure can optionally be blended with other lube base stocks to form lubricants. Useful co-base lube stocks include Group II, III, IV and V base stocks and gas-to-liquid (GTL) oils. One or more of the co-base stocks may be blended into a lubricant composition including the lube base stock with improved filterability at from 0.1 to 50 wt. %, or 0.5 to 40 wt. %, 1 to 35 wt. %, or 2 to 30 wt. %, or 5 to 25 wt. %, or 10 to 20 wt. %, based on the total lubricant composition.
Lubricants including lube base stocks with improved filterability of the present disclosure may optionally include lube base stock additives, such as detergents, dispersants, antioxidants, anti-wear additives, viscosity index modifiers, pour point depressants, friction modifiers, de-foaming agents, corrosion inhibitors, wetting agents, rust inhibitors, and the like. The additives are incorporated with the lube base stocks of the present disclosure to make a finished lubricant that has desired viscosity and physical properties. Typical additives used in lubricant formulation can be found in the book “Lubricant Additives, Chemistry and Applications”, Ed. L. R. Rudnick, Marcel Dekker, Inc, 270 Madison Ave. New York, NJ 10016, 2003.
When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount effective for it to perform its intended function. Typical amounts of such additives useful in the present invention are shown in Table 1 below. The total of the additional additives in the lubricating oil composition may range from 0.1 to 50 wt. %., or 0.5 to 40 wt. %, 1 to 35 wt. %, or 1 to 20 wt. % of the composition, or 2 to 18 wt. %, or 3 to 15 wt. %, or 4 to 10 wt. %, or 5 to 8 wt. %. Note that many of the additives are shipped from the manufacturer and used with a certain amount of base stock solvent in the formulation. Accordingly, the weight amounts in the table below, as well as other amounts mentioned in this patent, unless otherwise indicated are directed to the amount of active ingredient (that is the non-solvent portion of the ingredient).
The wt. % indicated below are based on the total weight of t bricating oil composition.
The lube base stocks with improved filterability and lubricating oils may be employed in the present disclosure in a variety of lubricant-related end uses, such as a lubricant oil or grease for a device or apparatus requiring lubrication of moving and/or interacting mechanical parts, components, or surfaces. Useful apparatuses include engines and machines. The lubricating oils with improved filterability of the present disclosure are most suitable for use in the formulation of automotive crank case lubricants, automotive gear oils, transmission oils, many industrial lubricants including circulation lubricant, industrial gear lubricants, grease, compressor oil, pump oils, refrigeration lubricants, hydraulic lubricants, metal working fluids.
The determination of filterability performance of the lubricant base stocks was determined by the Membrane Filtration Method for determining sediment and filterability of industrial oils. This is ExxonMobil Analytical Test Method 1082-01. This internal test method was adopted in 1971; and revised in 1974, 1976, 1985, 1993, 1998, and 2001. The test method is as follows:
8.1.1 Place a 0.8-micron membrane in an aluminum weighing dish with the correct side up (Note 3) and dry for 10 minutes in an oven at 75±2° C. Remove the dish and cool for about 10 minutes in a dust-free area, such as a covered drying block. Remove the membrane from the dish, weigh to the nearest 0.1 mg, and record the weight as W1. Place it correct side up on the stainless steel support, attach the funnel, and clamp together.
where:
Sediment, mg per 75 ml of oil=W2−W1
where:
The following are examples of the present disclosure and are not to be construed as limiting.
In this Example, blends of bright stock and Group I heavy neutral were made at FIN treat rates or loadings ranging from 1.0 wt.% to 50 wt. %. The bright stock/RN blends along with the bright stock with no RN (control or comparative example) and the Group I HN were then tested for 5 micron filterability using the procedure detailed in the Test Methods section. The bright stock with no RN had a 5 micron filterability of greater than 1800 seconds and the HN had a filterability of 59 seconds.
In this example, blends of bright stock and 1 wt. % heavy neutral were prepared. The bright stock/HN blends were then tested for filterability using the procedure detailed in the Test Methods section at various times after blending to determine the impact of time after blending on filterability performance. This was to determine the stability of the blends incorporating the HN with regard to filterability performance. The times after blending prior to filterability testing were 24 hours, 1-week, 2-weeks, 3-weeks and 4-weeks. The blends were stored at room temperature for the time periods. Also tested for filterability was bright stock with no HN (control or comparative example) of known poor filterability performance as measured in the EM membrane filtration test. The bright stock with no HN had a filterability of greater than 1800 seconds.
Applicants have attempted to disclose all embodiments and applications of the disclosed subject matter that could be reasonably foreseen. However, there may be unforeseeable, insubstantial modifications that remain as equivalents. While the present invention has been described in conjunction with specific, exemplary embodiments thereof, it is evident that many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description without departing from the spirit or scope of the present disclosure. Accordingly, the present disclosure is intended to embrace all such alterations, modifications, and variations of the above detailed description.
All patents, test procedures, and other documents cited herein, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.
When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated.
