Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic oxygen compound
Reexamination Certificate
2001-04-06
2002-08-20
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic oxygen compound
C508S539000, C508S562000
Reexamination Certificate
active
06436883
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to hydraulic fluids useful in a wide variety of applications where a hydraulic fluid is employed to transmit fluid pressure. The invention relates more particularly to hydraulic fluids which are intended to be used in locations near environmental water sources, such as streams, rivers, lakes, and oceans. The fluids according to the invention possess strong dispersant qualities sufficient to leave no sheen in cases of their accidental release to environmental water sources. The hydraulic fluids of the invention are extremely low in toxicity to aquatic life and thus pose a minimal risk to ecosystems.
BACKGROUND
Hydraulic fluids are used in systems which are generally well-known in the art for providing a means for transmitting any applying large forces to moveable mechanical components, while retaining a great degree of flexibility and control. Such systems are used in most forms of mechanized motion to transmit, transform and control mechanical work. They are part of a major technical discipline known to those skilled in the art as “fluid power technology”.
A typical hydraulic system includes the following components: 1) a force-generating unit that converts mechanical energy into hydraulic energy, such as a pump; 2) a hydraulic fluid; 3) piping for transmitting fluid under pressure; 4) a unit that converts the hydraulic energy of the fluid into mechanical work, such as an actuator or fluid motor; 5) A control circuit with valves that regulate flow, pressure, direction of movement, and applied forces; and 6) a fluid reservoir that allows for filtration and/or separation of any particulate debris or water before returning the clean fluid to the system. Thus, the fluid is in contact with each mechanical component of the system used for transmitting mechanical energy, including metallic components which may come into direct physical contact with one another.
It is generally accepted that hydraulic fluids can be defined as any liquids which are necessary for the proper functioning of a hydraulic system. The primary function of the fluid is to transmit force which is applied at one point in the system to some other location in the system, and to quickly produce desired changes in the direction or the magnitude of that force. Hydraulic systems using such suitable fluids are very common and have numerous applications in industry and daily life, including uses in automotive systems such as brakes, clutches, and transmissions, in industrial equipment for applications such as pressing, molding, mining, metal forming and positioning, excavation equipment such as backhoes, in devices such as elevators, and in the transportation industry for many control and motive systems in ships and aircraft. The art of hydraulic fluid formulation contains several technical references which describe hydraulic fluids which are based upon hydrocarbon oils. Such systems include those described in U.S. Pat. Nos. 2,403,067; 2,892,854; 2,967,831; 4,151,101; 4,208,293; 4,293,432; and 4,557,846, the entire contents of each of which are herein incorporated by reference thereto.
For optimal functioning, a hydraulic fluid must be relatively incompressible and must flow readily. In addition, there are a number of secondary functions provided by hydraulic fluids, which functions are extremely important for successful system operation, including adequate lubricity for moving parts, stability under anticipated conditions of use, compatibility with materials used to construct the hydraulic system, and the fluids should have the ability to protect system components against chemical reaction with materials which may enter the system.
Additives to the fluid which protect system components against chemical reaction are frequently called “corrosion inhibitors”. Corrosion can result from the formation of reactive decomposition products of the fluid itself, from components of the fluid (e.g., additives) which are corrosive, or from the entry of contaminants into the hydraulic system.
In the case of hydraulic fluids which are based upon hydrocarbon oils, an environmental problem arises when such fluids come into contact with environmental water sources in that at least a portion of the oils tend to float on the surface of the water and create an unsightly sheen which may extend or be visible for great distances. This is known to be the case even when the total amount of the oil accidentally spilled is relatively small, and the concentration of the oil on surface of the water poses potential harm to aquatic life forms. Such situations have in the past commonly arisen for ships at sea, when there is a leak of a hydraulic fluid used in one of the ship's operating systems, and in general in any situation where hydraulic fluids are used in close proximity to environmental water sources, such as oil drilling platforms, paper mills, and amusement parks. As the United States government has promulgated rules concerning releases of materials that useful as hydraulic fluids in Title 40 of the Code of Federal Regulations, section 110, an increased level of awareness of issues surrounding spills of hazardous oils has become manifest in recent years. In response with such rulemaking, many users of hydraulic oils have undertaken to employ special precautions in their handling and use of hydraulic fluids. Clearly, if formulations of hydraulic fluids were available that do not form a sheen on the surface of water into which such fluids came into contact and which are environmentally benign, such fluids would be welcomed by all persons to whom such fluid types are of practical use.
SUMMARY OF THE INVENTION
The problems associated with the use of and release into environmental waters of water-immiscible, hydrocarbon oil based hydraulic oil formulations may be eliminated by the use of a liquid composition according to the present invention, which comprises water-soluble polyoxyalkylene glycols having either of the general formulae:
in which x is selected from any whole integer 1, 2, 3, 4, or 5; y is selected from 1 or 2; and m is an integer sufficient to provide a molecular weight in the range of between about 450 and 5000. Such materials are used in combination with a carboxylic acid having between about 6 and 18 carbon atoms per molecule of carboxylic acid, an amine, and optionally, an extreme pressure additive to provide a composition according to the invention. Since the physical properties and performance characteristics required of hydraulic fluids are similar to those required by gear oils in many applications, the formulations of the invention are of widespread applicability.
DETAILED DESCRIPTION
The present invention comprises multi-component liquid compositions of matter which comprise a predominant amount of a water-soluble polyoxyalkylene glycol having a pre-selected molecular weight of any value in the range of between 450 and 5000. When formulated according to the present invention, the functional fluids disclosed provide an excellent viscosity index which is greater than about 160. An especially preferred family of water soluble polyoxyalkylene glycol useful in the compositions of the present invention may also be one produced from alkoxylation of n-butanol with a mixture of alkylene oxides to form a random alkoxylated product which may be described by the either of the general formulae:
in which x may independently be any whole integer between 0 and 5, including 0 and 5; y may independently be any integer between 0 and 2, including 0 and 2; may independently be any whole integer between 1 and 5, including 1 and 5; p may independently be either 1 or 2; wherein m is an integer within the range suitable to provide a molecular weight of between 450 to 5000.
Functional fluids according to the invention possess a pour point of less than about −20° C., and exhibit compatibility with a wide range of anti-wear additive and extreme pressure additives. The formulations according to the invention also are devoid of fatigue failure that is normally expected by those of ordinary
Brown Ron D.
Huntsman Petrochemical Corporation
McAvoy Ellen M.
Stolle Russell R.
Whewell Christopher J.
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