Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Silicon dioxide – silicic acid – orthosilicate – or...
Reexamination Certificate
2000-03-27
2001-12-18
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Silicon dioxide, silicic acid, orthosilicate, or...
C508S137000, C508S138000, C508S141000, C508S181000, C508S491000
Reexamination Certificate
active
06331509
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates to improved grease compositions as well as grease compositions capable of imparting improved corrosion resistance.
BACKGROUND OF THE INVENTION
The American Society for Testing and Materials (ASTM D288 standard definition of the terms relating to petroleum) defines a lubricating grease as a solid to semi-fluid product of dispersion comprising a thickening agent and a liquid lubricant. Other ingredients imparting special properties may be included. This definition indicates that a grease is a liquid lubricant thickened in order to provide properties that are not provided solely by the liquid lubricant. Typically, greases are employed in dynamic rather than static applications. Gels are normally classified as a colloid and provide utility in non-dynamic applications ranging from sol-gels to cosmetic applications.
Conventional grease formulations are described in “Synthetic Lubricants and High-Performance Functional Fluids”, edited by Ronald L. Shubkin (dated 1993). The characteristics of soap based greases, additives and methods for making conventional greases are described in “The Chemistry of Soap Base Greases” by Glen Brunette, “Additives For Grease”, by Dr. Miles Hutchings and “Grease Manufacture in Conventional Kettles” by K. F. Montgomery all of which were presented at the 63rd NLGI Annual Meeting, October 1996. The disclosure of the previously identified publications is hereby incorporated by reference.
Commercial industrial practice employs lubricating films and greases to prevent galling and fretting. The increased efficiency and complexity of modern machines often require such films and greases to perform under severe operating and environmental conditions. While the composition of a gel may be similar to a grease, typically gels are employed to solve non-lubricating problems. There is a need in this art for lubricants, greases and gels that also impart corrosion resistance.
SUMMARY OF THE INVENTION
The instant invention solves problems associated with conventional lubricants and greases by providing an improved composition which imparts corrosion and microbial resistance, and a high dropping point. By “dropping point” it is intended to mean the temperature at which lubricating compositions become fluid and thereby able to drip through an orifice in accordance with ASTM D2265. The inventive grease typically has a minimum dropping point of about 250° C.
The instant invention also provides a composition that can offer an alternative to conventional greases and gels thereby also avoiding the environmental and manufacturing problems associated with conventional grease products. The inventive greases and gels can be tailored to range from microbial resistant to biodegradable; but in either case the greases/gels are non-toxic. By “non-toxic” it is meant satisfying the standards for toxicity set forth in ASTM E-729-88a. While the instant invention is compatible with a wide range of metals and metallic coatings, the instant invention can also obviate the usage of environmentally undesired metals, e.g., chrome, that are conventionally employed for imparting corrosion resistance. Similarly, while the instant invention can be employed with a solvent, in certain aspects the inventive grease/gel can be solvent free or substantially solvent free. By “substantially solvent free”, it is meant that the grease/gel contains less than about 30 wt. %; and normally less than 10 wt. %, of volatile organic compounds (otherwise known as V.O.C.s). By “solvent free” it is mean that the grease/gel contains less than 5 wt. % and normally less than 1 wt. % of volatile organic compounds (V.O.C.s).
The inventive grease/gel can be employed as a substitute for conventional greases/gels; especially in environments where improved corrosion resistance is desired, e.g., wire rope and strand that is used in a wide range of applications including automotive and marine end-uses. Further, the inventive grease/gel can be employed for reducing, if not eliminating, corrosion under insulation (CUI). That is, corrosion upon metallic surfaces which are covered by an insulating covering or layer, e.g., a mechanically attached insulating sleeve upon a pipe. CUI is particularly problematic in the petroleum industry wherein corrosion can occur under refinery pipes, cracking columns, oil/gas pipelines, reaction vessels, among other areas. Corrosion under insulation can also occur in heating ventilation and cooling (HVAC) water lines, steam lines for chemical processing and power generation, conduits/piping on ships, among other areas. In addition, the inventive compositions can improve resistance to stress crack corrosion, among other benefits.
The instant invention can also offer an alternative to silicone containing lubricants. For example, in automotive painting environments silicone oils have been associated with adverse affects, e.g., on the quality of painted surfaces due to low molecular fractions of the silicone becoming air-borne under ambient conditions. The instant invention, however, can improve the corrosion resistance of silicon containing lubricants and gels.
The inventive grease/gel can also be employed upon chains, gears, pulleys, wire rope or strand for end-uses in automotive, industrial, marine cables, among other uses. The inventive grease/gel can be employed to protect pipe flanges. For example, a carbon steel pipe flange connected by carbon steel bolts can be protected by applying the inventive grease/gel upon and within the flange, and wrapping the flange with a tape, e.g., aluminum, fiber reinforced, typically with an adhesive. The flange wrap can be affixed by using any suitable fastening means such as metal bands, clamps, adhesives, among others.
The fluid or liquid portion of the inventive grease/gel can comprise a base oil comprising at least one member selected from the group consisting of mineral oil, synthetic oil, vegetable oil, fish oil, animal oil among any suitable fluid having lubricating properties. Examples of suitable base oils include at least one member from the group consisting of animal, vegetable, petroleum derived and synthetic oils such as polyalphaolefin (PAO), silicone oil, phosphate esters, fluorinated oils such as KRYTOX (supplied by the DuPont Company, Wilmington, Del.), mixtures thereof, e.g., a base oil comprising a mixture of vegetable and synthetic oils, among others. Typically, the base oil will comprise about 45 to about 90 wt. % of the grease e.g., about 70 wt. % to about 90 wt. %.
Environmentally preferred lubricants (EPL's) are preferred as base oils in applications where loss of material to the environment can occur. EPL's have the distinction of being biodegradable and/or essentially non-toxic. Biodegradable base oils include, but are not limited to fish oils, vegetable oils, lanolin, synthetic esters, low molecular weight polyalfaolefins, and polyalkylene glycols. Essentially non-toxic base oils include but are not limited to polyalfaolefins, polybutenes, vegetable oils and also lanolins. Examples of suitable vegetable base oils comprise at least one member from the group consisting of rapeseed oil, canola oil, soybean oil, corn oil, cottonseed oil, linseed oil, olive oil, tung oil, peanut oil, meadowfoam oil, sunflower oil, safflower oil, jojoba oil, palm oil, castor oil, among others. The vegetable base oil can be obtained from a genetically modified plant or be modified by water washing, refining, esterification, hydrolysis, etc.; thereby producing an oxidation resistant base oil e.g. high oleic soybean oil.
For applications requiring that the grease be exposed to a relatively high or low temperature, or wide variation in temperature during operation, synthetic fluids are typically employed, e.g., a diester oil based grease. If the grease comprises a metallic soap grease, then complexing agents can be employed for improving the so-called “dropping point” of the grease. Such agents are usually present in an amount from about 5 to about 25 wt. % of the grease.
A thickener is combined with a base
Dalton William M.
Heimann Nancy M.
Heimann Robert L.
Scrivens Todd W.
Taylor Donald W.
Boyer Michael K.
Elisha Technologies Co LLC
Medley Margaret
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