Patent Application
20070297279
The present invention relates to a method of blending high viscosity lubricant components comprising the use of positive-displacement pipettes. The method of blending high viscosity lubricant components of the present invention are distinguishable over the prior art in disclosing the use of positive displacement pipettes to accurately meter small quantities of high viscosity lubricant additives into a lubricant formulation. The advantages of the disclosed method of the present invention include, inter alia, improved dispensing accuracy, lower shear rate during dispensing, lower temperature for dispensing, less residual additive on the tip of the device after dispensing, and the ability to real time monitor density and mass during dispensing.
Blends made according to volume concentration are generally made using air displacement pipettes or air/liquid displacement liquid handling systems. In an air displacement pipette, a source of air is attached to the end of the pipette and suction is applied to draw fluid into the pipette. The pipette is then placed in the receiving vessel and gas is applied to eject liquid into the receiving vessel. In a combined air/liquid displacement liquid handling system, the suction is provided by a pump and action is transferred through a system liquid and the air gap between the system liquid and the liquid to be transferred. Different pipettes can be used for each lubricant component. Alternatively, a single pipette may be used if it is cleaned between exposure to different lubricant blend components in order to avoid contamination and inaccuracies.
In some applications, for example in laboratory applications, it is desirable to make very small quantities of lubricant blends. Small blends enable testing of precious additives made experimentally in small quantities and help to minimize waste when only small amounts are needed for testing purposes. It is also sometimes desirable to rapidly make large arrays of small lubricant blends. In this way lubricant blend compositions can be rapidly evaluated in various lubricant screening procedures. The process of rapidly making large arrays of small test samples and rapidly evaluating them is known as high throughput experimentation (HTE).
Lubricants are typically blended from several components of different molecular weight and viscosity. High viscosity lubricant components are sometimes used to modify the viscometric properties of the lubricant blend. These viscosity modifiers are typically comprised of high molecular weight polymers. It is especially difficult to accurately measure the volume of high viscosity lubricant components blended into small blends when air displacement pipettes are used in a conventional way because of two factors. One factor is that viscous liquids generate significant resistance to the applied gas pressure, and gas compression can result in less liquid being ejected from the pipette than anticipated. A second factor is that because high viscosity lubricant components are typically polymers, they tend to form a stringy residue inside the pipette near tip. Consequently, less liquid ends up in the receiving vessel than was expelled from the pipette, which may lead to blending inaccuracies. The error introduced by these two factors is exacerbated when making small blend quantities.
In many cases high viscosity lubricant components are blended after heating them to a temperature sufficient to reduce their viscosity to a range where they can be handled like low viscosity liquids. Alternatively, they may be diluted with low viscosity solvents. In this way they can be easily pipetted with standard air displacement pipettes and can be accurately dispensed. However, elevated temperature can cause high viscosity lubricant components to discolor or degrade. It is therefore desirable to blend them with minimal heating.
Another issue is that high viscosity lubricant components may degrade under high shear flow conditions. Shear degradation may occur when such additives are forced under pressure through a small orifice such as the exit opening on a pipette. High viscosity lubricant components are often comprised of high molecular weight polymers. When these polymers are forced through a small opening, the shear rate and shear stress may be sufficiently high to cause breaking of chemical bonds, which lowers the molecular weight and the associated benefits of the high molecular weight molecules in the lubricant blend.
An object of the present invention is to improve the accuracy of small lubricant blends containing high viscosity lubricant components made in a laboratory without causing degradation of the high viscosity lubricant component. In making a lubricant blend containing several components, it is necessary to accurately monitor the concentration of each component of the blend. When a blend is relatively large in volume, it is less complex to measure the concentration of individual components. Typically blends can be made by controlling the concentration by weight of each component or by volume of each component.
A further object of the present invention is to provide a method for accurately producing small lubricant blends, which include high viscosity lubricant components. These small lubricant blends contain preferably less than 100 milliliters of total volume, more preferably less than 25 milliliters of total volume, and even more preferably less than 10 milliliters of total volume.
The present invention relates to the discovery that accuracy of small lubricant blends containing high viscosity components can be improved by using pipettes activated by movement of a piston with a shaft all the way to the tip, which are defined as positive displacement pipettes (herein also referred to as “PDP”). Such pipettes are typically gear driven and generate sufficient pressure to ensure that all liquid residing in the pipette barrel is ejected. PDPs improve blend accuracy because the piston displaces a constant volume of liquid regardless of liquid viscosity. However, the piston may generate high pressure in the liquid, which is particularly relevant when using pipettes with a small orifice as is necessary when making small blend quantities. When using pipettes with a small orifice to dispense high viscosity lubricant components, shear rate and shear stress must be such as to not cause degradation of the lubricant components. Shear rate and shear stress are proportional to the rate of flow through an orifice, and therefore to minimize lubricant degradation, it is important to keep flow rates below certain threshold shear rates. The flow rate of the high viscosity component flowing through an orifice should be controlled to keep the shear rate below 5×106 sec−1, preferably below 1×106 sec−1, more preferably below 1×105 sec−1, and even more preferably below 1×104 sec−1.
The disclosed method of blending lubricant additives using tubeless positive-displacement pipettes is particularly suitable for dispensing high viscosity lubricant components or additives. A high viscosity lubricant component or additive is defined as a liquid with a viscosity greater than 100 centipoise at 100° C. The method of the present invention is particularly suitable for dispensing lubricant components or additives with a viscosity of greater than 500 centipoise at 100° C., and even more particularly suitable for dispensing lubricant components or additives with a viscosity of greater than 1000 centipoise at 100° C.
Lubricant additives or components include, but are not limited to, viscosity modifiers, dispersants, detergents, pour point depressants, polyisobutylenes, high molecular weight polyalphaolefins, antiwear/extreme pressure agents, antioxidants, demulsifiers, seal swelling agents, friction modifiers, corrosion inhibitors, and antifoam additives, as well as packages containing mixtures of these lubricant additives, such as for example mixtures of dispersants, detergents, antiwear/extreme pressure agents, antioxidants, demulsifiers, seal swelling agents, friction modifiers, corrosion inhibitors, antifoam additives, and pour point depressants. High viscosity lubricants include, but are not limited to, viscosity modifiers, pour point depressants, dispersants, polyisobutylenes, and high molecular weight polyalphaolefins and additive packages containing one or more of these high viscosity lubricants. The disclosed method of blending lubricant additives using positive-displacement liquid-handling equipment method also allows blending to be done with minimal chemical, thermal or physical degradation of the high viscosity lubricant components within the lubricant blend.
Viscosity modifiers (also known as VI improvers and viscosity index improvers) provide lubricants with high and low temperature operability. These additives impart higher viscosity at elevated temperatures, and acceptable viscosity at low temperatures.
Suitable viscosity index improvers include high molecular weight (polymeric) hydrocarbons, polyesters and viscosity index improver dispersants that function as both a viscosity index improver and a dispersant. Typical molecular weights of these polymers are between about 10,000 to 1,000,000, more typically about 20,000 to 500,000, and even more typically between about 50,000 and 200,000.
Examples of suitable viscosity index improvers are polymers and copolymers of methacrylate, butadiene, olefins, or alkylated styrenes. Polyisobutylene is a commonly used viscosity index improver. Another suitable viscosity index improver is polymethacrylate (copolymers of various chain length alkyl methacrylates, for example), some formulations of which also serve as pour point depressants. Other suitable viscosity index improvers include copolymers of ethylene and propylene, hydrogenated block copolymers of styrene and isoprene, and polyacrylates (copolymers of various chain length acrylates, for example). Specific examples include olefin copolymer and hydrogenated styrene-isoprene copolymer of 50,000 to 200,000 molecular weight.
Viscosity modifiers are used in an amount of about 1 to 25 wt % on an as received basis. Because viscosity modifiers are usually supplied diluted in a carrier or diluent oil and constitute about 5 to 50 wt % active ingredient in the additive concentrates as received from the manufacturer, the amount of viscosity modifiers used in the formulation can also be expressed as being in the range of about 0.20 to about 3.0 wt % active ingredient, preferably about 0.3 to 2.5 wt % active ingredient. For olefin copolymer and hydrogenated styrene-isoprene copolymer viscosity modifier, the active ingredient is in the range of about 5 to 15 wt % in the additive concentrates from the manufacturer, the amount of the viscosity modifiers used in the formulation can also be expressed as being in the range of about 0.20 to 1.9 wt % active ingredient, and preferably about 0.3 to 1.5 wt % active ingredient.
During engine operation, oil-insoluble oxidation byproducts are produced. Dispersants help keep these byproducts in solution, thus diminishing their deposition on metal surfaces. Dispersants may be ashless or ash-forming in nature. Preferably, the dispersant is ashless. So called ashless dispersants are organic materials that form substantially no ash upon combustion. For example, non-metal-containing or borated metal-free dispersants are considered ashless. In contrast, metal-containing detergents discussed above form ash upon combustion.
Suitable dispersants typically contain a polar group attached to a relatively high molecular weight hydrocarbon chain. The polar group typically contains at least one element of nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.
Chemically, many dispersants may be characterized as phenates, sulfonates, sulfurized phenates, salicylates, naphthenates, stearates, carbamates, thiocarbamates, phosphorus derivatives. A particularly useful class of dispersants are the alkenylsuccinic derivatives, typically produced by the reaction of a long chain substituted alkenyl succinic compound, usually a substituted succinic anhydride, with a polyhydroxy or polyamino compound. The long chain group constituting the oleophilic portion of the molecule which confers solubility in the oil, is normally a polyisobutylene group. Many examples of this type of dispersant are well known commercially and in the literature. Exemplary U.S. patents Nos. describing such dispersants, and incorporated by reference in their entirety, are U.S. Pat. Nos. 3,172,892; 3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458, also incorporated by reference in their entirety. A further description of dispersants may be found, for example, in European Patent Application No. 471 071, also incorporated by reference in its entirety.
Hydrocarbyl-substituted succinic acid compounds are popular dispersants. In particular, succinimide, succinate esters, or succinate ester amides prepared by the reaction of a hydrocarbon-substituted succinic acid compound preferably having at least 50 carbon atoms in the hydrocarbon substituent, with at least one equivalent of an alkylene amine are particularly useful.
Succinimides are formed by the condensation reaction between alkenyl succinic anhydrides and amines. Molar ratios can vary depending on the polyamine. For example, the molar ratio of alkenyl succinic anhydride to TEPA can vary from about 1:1 to about 5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800; and Canada Pat. No. 1,094,044, all of which are incorporated by reference in their entirety.
Succinate esters are formed by the condensation reaction between alkenyl succinic anhydrides and alcohols or polyols. Molar ratios can vary depending on the alcohol or polyol used. For example, the condensation product of an alkenyl succinic anhydride and pentaerythritol is a useful dispersant.
Succinate ester amides are formed by condensation reaction between alkenyl succinic anhydrides and alkanol amines. For example, suitable alkanol amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpolyamines and polyalkenyl-polyamines such as polyethylene polyamines. One example is propoxylated hexamethylenediamine. Representative examples are shown in U.S. Pat. No. 4,426,305, which is incorporated by reference in its entirety.
The molecular weight of the alkenyl succinic anhydrides used in the preceding paragraphs will typically range between 800 and 2,500. The above products can be post-reacted with various reagents such as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic acid, and boron compounds such as borate esters or highly borated dispersants. The dispersants can be borated with from about 0.1 to about 5 moles of boron per mole of dispersant reaction product.
Mannich base dispersants are made from the reaction of alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which is incorporated herein by reference. Process aids and catalysts, such as oleic acid and sulfonic acids, can also be part of the reaction mixture. Molecular weights of the alkylphenols range from 800 to 2,500. Representative examples are also shown in U.S. Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039, all of which are herein incorporated by reference in their entirety.
Typical high molecular weight aliphatic acid modified Mannich condensation products useful in this invention can be prepared from high molecular weight alkyl-substituted hydroxyaromatics or HN(R)2 group-containing reactants.
Examples of high molecular weight alkyl-substituted hydroxyaromatic compounds are polypropylphenol, polybutylphenol, and other polyalkylphenols. These polyalkylphenols can be obtained by the alkylation, in the presence of an alkylating catalyst, such as BF3, of phenol with high molecular weight polypropylene, polybutylene, and other polyalkylene compounds to give alkyl substituents on the benzene ring of phenol having an average 600-100,000 molecular weight.
Examples of HN(R)2 group-containing reactants are alkylene polyamines, principally polyethylene polyamines. Other representative organic compounds containing at least one HN(R)2 group suitable for use in the preparation of Mannich condensation products are well known and include the mono- and di-amino alkanes and their substituted analogs, e.g., ethylamine and diethanol amine; aromatic diamines, e.g., phenylene diamine, diamino naphthalenes; heterocyclic amines, e.g., morpholine, pyrrole, pyrrolidine, imidazole, imidazolidine, and piperidine; melamine and their substituted analogs.
Examples of alkylene polyamide reactants include ethylenediamine, diethylene triamine, triethylene tetraamine, tetraethylene pentaamine, pentaethylene hexamine, hexaethylene heptaamine, heptaethylene octaamine, octaethylene nonaamine, nonaethylene decamine, and decaethylene undecamine and mixture of such amines having nitrogen contents corresponding to the alkylene polyamines, in the formula H2N-(Z-NH—)nH, mentioned before, Z is a divalent ethylene and n is 1 to 10 of the foregoing formula. Corresponding propylene polyamines such as propylene diamine and di-, tri-, tetra-, pentapropylene tri-, tetra-, penta- and hexaamines are also suitable reactants. The alkylene polyamines are usually obtained by the reaction of ammonia and dihalo alkanes, such as dichloro alkanes. Thus the alkylene polyamines obtained from the reaction of 2 to 11 moles of ammonia with 1 to 10 moles of dichloroalkanes having 2 to 6 carbon atoms and the chlorines on different carbons are suitable alkylene polyamine reactants.
Aldehyde reactants useful in the preparation of the high molecular products useful in this invention include the aliphatic aldehydes such as formaldehyde (also as paraformaldehyde and formalin), acetaldehyde and aldol (β-hydroxybutyraldehyde). Formaldehyde or a formaldehyde-yielding reactant is preferred.
Hydrocarbyl substituted amine ashless dispersant additives are disclosed, for example, in U.S. Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433; 3,822,209 and 5,084,19; all of which are herein incorporated by reference.
Preferred dispersants include borated and non-borated succinimides, including those derivatives from mono-succinimides, bis-succinimides, and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is derived from a hydrocarbylene group such as polyisobutylene having a Mn of from about 500 to about 5000 or a mixture of such hydrocarbylene groups. Other preferred dispersants include succinic acid-esters and amides, alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives, and other related components. Such additives may be used in an amount of about 0.1 to 20 wt %, preferably about 0.1 to 8 wt %.
Conventional pour point depressants (also known as lube oil flow improvers) may be added to the compositions of the present invention if desired. These pour point depressant may be added to lubricating compositions of the present invention to lower the minimum temperature at which the fluid will flow or can be poured. Examples of suitable pour point depressants include polymethacrylates, polyacrylates, polyarylamides, condensation products of haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479; 2,666,746; 2,721,877; 2.721,878; and 3,250,715, all of which are herein incorporated by reference, describe useful pour point depressants and/or the preparation thereof. Such additives may be used in an amount of about 0.01 to 5 wt %, preferably about 0.01 to 1.5 wt %.
When lubricating oil compositions contain one or more of the additives discussed above, the additive(s) are blended into the composition in an amount sufficient for it to perform its intended function. Exemplary amounts of such additives useful in the present invention are depicted in Table 1 below. Note that many of the additives are shipped from the manufacturer and used with a certain amount of base oil solvent in the formulation. Accordingly, the weight amounts in the table below, as well as other amounts referenced in the present disclosure, unless otherwise indicated, are directed to the amount of active ingredient (that is the non-solvent portion of the ingredient). The weight percentages indicated below are based on the total weight of the lubricating oil composition.
3–20
Commercial additive packages usually include, but are not limited to, one or more detergents, dispersants, friction reducers, antioxidants, corrosion inhibitors, and anti-wear additives.
An exemplary, but not limiting, engine oil formulation will contain 70-90 wt % base oil, 4-10 wt % VI improver, 4-10 wt % dispersants, 1-3 wt % antiwear/extreme pressure agents, 0.2-2 wt % antioxidants, 1-4% detergents, 0.01-0.1 wt % each of demulsifier, seal swelling agent, friction modifier, and antifoam additive, 0.1-0.5 wt % pour point depressant. In some cases, some of these additives are packaged together by an additive supplier. In these additives, the VI improver and dispersants are high viscosity components (13,000-17000 centipoise under low shear condition). When heated to about 90° C., the viscosities of these two components decrease to a viscosity from about 500 to about 2000 centipoise under low shear conditions, which are still difficult to handle with the traditional liquid handling equipment.
Many PDPs have a piston or plunger which slides inside a barrel, the tip of which is tapers to a fine point. Sometimes this tip can be very fine, especially where a high degree of blend accuracy is desired. If the piston and barrel are not be fitted to one another when the piston is pressed into the barrel to eject a volume of liquid, not all the liquid will be ejected because there is a void volume between the piston and the barrel. In addition, air can be trapped between the piston and the liquid. Low Void Volume Positive Displacement Pipettes (herein also referred to as “LVVPDP”) are pipettes that have pistons or plungers matched in shape and size to the pipette barrel and dispensing tip or needle. This minimizes the gap between the plunger or piston and the inside of the pipette barrel and dispensing tip/needle. In a LVVPDP, the void volume is less than 1 milliliter, preferably less than 0.5 milliliter, more preferably less than 0.05 milliliter, and even more preferably less than 0.5 microliter or essentially zero to minimize the amount of liquid or air trapped between the piston and the liquid. A LVVPDP may be alternatively defined by the % volume of the dispensing tip or needle that is filled by the plunger. For this alternative definition of a LVVPDP, it is one having at least 70% of the volume of the dispensing tip or needle filled by the plunger, therefore resulting in a void volume of the tip or needle of 30% or less of the total volume of the tip or needle. More preferably, a LVVPDP is one having at least 90% of the volume of the dispensing tip or needle filled by the plunger, therefore resulting in a void volume of the tip or needle of 10% or less of the total volume of the tip or needle. Even more preferably, a LVVPDP is one having at least 98% of the volume of the dispensing tip or needle filled by the plunger, therefore resulting in a void volume of the tip or needle of 2% or less of the total volume of the tip or needle.
Two representative types of low void positive displacement pipettes are shown in
An advantage of using a LVVPDP to dispense lubricant additives is that individual pipettes may be used for each individual additive. In the case of air-displacement or liquid/air displacement pipettes, each pipette requires a separate pump. This results in a cumbersome system when many pipettes are used. LVVPDPs do not require pumps, and therefore equipment complexity and the possibility of contamination are avoided. Correspondingly, the overall lubricant blending system is simplified when using LVVPDPs.
The source array 46 may also include one or more heating blocks 24 to preheat the high viscosity additive in order to lower the viscosity. For example, in
The robotic arm 42 and support bridge 44 are controlled by a computer or a programmable logic controller (not shown) to control their movement relative to the source array 46 and the destination array 48 in order to pick-up and return LVVPDPs 10. The robotic arm 42 controlled by a computer or a programmable logic controller (not shown) is also used to control the amount of additive sucked into the LVVPDP 10 at the source array 46 from each additive reservoir 22 and the amount of additive dispensed at the destination array 48 into each destination blend container 52. The computer or programmable logic controller contains information on all the additives contained in the additive reservoirs 22. This information includes, but is not limited to, physical properties such as viscosity and density. The computer also has a list of blend recipes, which includes the concentration of each additive in the blend recipe. The computer or programmable logic controller also has a feedback control mechanism to the balance for controlling the weight of each additive component dispensed into the destination blend container 53. The computer or programmable logic controller includes a calibration routine for the stroke of the plunger 12 in the barrel 11 and needle 14 of the LVVPDP 10 versus the weight of a particular lubricant additive dispensed. The calibration routine and feedback control mechanism allows the lubricant blend station 40 of the present invention to more quickly and accurately dispense lubricant additive components into a destination blend container 53 positioned on the balance 54.
As the computer directs a LVVPDP 10 to withdraw a specific volume of high viscosity lubricant component from an additive reservoir 22 and deposit it into a destination blend container 53, it may make two or more measurements. The computer monitors the volume of high viscosity lubricant component withdrawn by the LVVPDP 10. In addition, the mass of high viscosity lubricant component deposited into the destination blend container 53 is measured by the balance 54 sitting under the destination blend container 53. The destination blend container for lubricants may accommodate less than 100 milliliters in volume, and preferably less than 10 milliliters in volume for producing small lubricant blends.
The LVVPDP 10 associated with each additive reservoir 22 in the source array 46 may also be a disposable-type pipette. In this case, the robotic arm 42 will pick up a disposable LVVPDP 10, move it to the appropriate additive reservoir 22 depending on the additive desired, load the disposable LVVPDP 10 with additive, move to the destination blend container 52 (could be on top of a balance), and inject the lubricant additive into the blend container 52. The destination blend container 53 may also optionally be sitting on the balance 54 at the time of injection to measure real time the weight of lubricant additive being dispensed. The disposable LVVPDP 10 is discarded once the additive has been added to all the required destination blend containers 52.
The positive displacement technology of the present invention still requires heating to handle high viscosity lubricant additives. However, by enabling more accurate blending of high viscosity lubricant components, the use of LVVPDPs results in more accurate blends without excessive heating of the high viscosity blend component. The temperature of the high viscosity blend component or additive should be below 110° C., preferably below 91° C., and more preferably below 51° C.
The accuracy of lubricant blends made with high viscosity lubricant blend components and method of the present invention may be further improved by simultaneously measuring the weight and volume delivered to the blend vessel. This may be done by comparing the volume pipetted by the LVVPDP to the volume calculated by multiplying the measured mass with the density of the high viscosity component stored in the computer. If the volume and mass measurements are not in agreement than an error condition may be reported by the computer.
In another exemplary embodiment of the present invention, density of a high viscosity lubricant component may be accurately measured while simultaneously making lubricant blends via the computer or programmable logic controller. This is done by using the volume and mass measurements made by the computer for each high viscosity lubricant component.
In yet another exemplary embodiment of the present invention, density of a high viscosity lubricant component may be measured over a range of temperatures by varying the temperature of the high viscosity lubricant components and measuring the volume and mass. The density is then calculated by the computer or programmable logic controller by dividing the mass by the volume.
In still yet another embodiment of the present invention, the identity of a given high viscosity lubricant component may be verified by comparing the density measured as above with an expected density stored in a computer database. If the two densities agree within a certain tolerance, than the identity of the high viscosity lubricant component is known to be correct. If the densities fall outside this tolerance than either the wrong high viscosity lubricant component has been used or its density is outside of the specification.
The accuracy of dispensing a given amount of lubricant additives can be further improved by using a combination of a large LVVPDP or a conventional pipette with a small LVVPDP. The large LVVPDP or the conventional pipette is used to dispense 90-99% of the target quantity and the actual quantity added is determined by the balance. The computer or the programmable logic controller then calculates the remaining amount to be added by the small LVVPDP. An automated feedback routine can be used to further improve the dispensing of lubricant additives from LVVPDPs and conventional pipettes.
The lubricant blend station including LVVPDPs for dispensing high viscosity additives of the present invention are suitable for laboratory applications where the blend quantities are relatively small. The lubricant blend station including LVVPDPs for dispensing high viscosity additives of the present invention are also suitable for high throughout experimentation (HTE) type applications. These applications do not limit the range of other applications for blending lubricants and lubricant additives where the lubricant blend station of the present invention may be utilized.
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.
The following examples illustrate the present invention and the advantages thereto without limiting the scope thereof.
Three lubricant additives were dispensed using the 10 μl Gilson Microman low void volume positive displacement pipettes (Type CP10) and the results are compared with those obtained using the Tecan Liquid Handling device which is based on air/liquid displacement. The descriptions and the typical properties of the additives used are given in Table 2.
It was found that the low void positive displacement pipettes Gilson Microman M10 gave excellent results at room temperature while the Tecan RSP100 liquid handling system could not handle the same components at room temperature. The results obtained using the Microman MIO is given in Table 3. In comparison, the data from the Tecan liquid handling system is given in Table 4.
It was also found that Microman M100 (100 μl) low void positive displacement pipettes also gave excellent dispensing precision at room temperature when compared with Tecan RSP100 liquid handling system. The results obtained using the Microman M10 is given in Table 5. In comparison, the data from the Tecan liquid handling system is given in Table 6.
Paratone 8011 was dispensed at room temperature, 50° C. and 90° C. using 2.5 ml Jencons Scientific positive displacement pipettes (488-008) with and without modification. A razor blade was used to cut the pipette tip to remove the air space near the end of the tip. The modification reduces the void of the pipette. It was found that the modification leads to improvement in dispensing precision at room temperature and at 50° C. However at 90° C., no advantage was observed. The data are given in Table 7.
