Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Inorganic compound
Reexamination Certificate
2001-10-19
2003-11-04
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Inorganic compound
C508S215000, C508S438000, C508S504000, C508S505000, C508S545000, C508S551000, C508S579000, C508S588000
Reexamination Certificate
active
06642186
ABSTRACT:
FIELD OF THE INVENTION
Organic compounds which are grafted with fluorinated olefins and contain groups which are adsorbed on metal surfaces are excellent additives to lubricants for reducing wear and/or friction between moving parts.
TECHNICAL BACKGROUND
Lubricants of various sorts are widely used in systems containing moving parts which rub against one another, and are primarily used to reduce wear between the parts and/or reduce friction between the parts, usually both. Secondarily they may perform other functions, such as protecting metal parts from corrosion. While a “base” material is usually used for the majority of a lubricant composition, various additives are usually also used in the composition, such as additives to reduce wear, reduce friction, prolong the life of the lubricant, make the lubricant useful over a wider temperature range, and for many other purposes. Therefore, improved (in price and/or lubricant properties) additives are constantly being sought.
The use of various fluorinated organic compounds in lubricant systems is known in the art, see for instance U.S. Pat. Nos. 2,433,844, 5,391,814 and Japanese Patent 2,604,186. However, many of these compounds have the disadvantage of being pure compounds (or defined mixtures thereof) which are expensive to synthesize, and therefore expensive to use. It would be preferable to use compounds which are relatively simple and therefore cheap to make, and to use these in relatively small quantities in lubricant systems, to keep cost down.
U.S. Pat. No. 2,562,547 describes the grafting of a variety of organic compounds with certain fluoroolefins such as tetrafluoroethylene (TFE), and uses for the various fluorinated products. The use of certain of these types of compounds as unexpectedly superior lubricant additives is not described.
U.S. Pat. No 5,032,306 describes the use of hydrocarbons grafted with perfluoroolefins as lubricants in certain refrigeration systems. No mention is made of grafting compounds which contain functional groups.
SUMMARY OF THE INVENTION
This invention concerns a composition comprising:
(a) a major portion of a lubricant base; and
(b) a minor portion of a first lubricant additive which is an organic compound which is grafted with one or more fluorinated olefins and which, when combined with a lubricant base, forms a lubricant;
and provided that:
said additive contains at least 5 percent by weight of fluorine; and
said organic compound contains at least one functional group which can be adsorbed on a metal surface and wherein said functional group is selected from the group consisting of carboxylic esters, carboxylic acids, carboxylic amides, imides, amines, phosphoric acid derivatives, phosphonic acid derivatives, dithiophosphate esters, ethers, hydroxyls, carbonates, thio derivatives thereof, and heterocyclic groups.
The invention also concerns an apparatus, comprising:
(a) a first part which is metal;
(b) a second part which is in apparent contact with said first metal part, and said first part and second part move with respect to one another; and
(c) a lubricant which comprises:
(i) a major portion of a lubricant base; and
(ii) a minor portion of a first lubricant additive which is an organic compound which is grafted with one or more fluorinated olefins and which, when combined with a lubricant base, forms a lubricant;
and provided that:
said additive contains at least 5 percent by weight of fluorine; and
said organic compound contains at least one functional group which can be adsorbed on a metal surface and wherein said functional group is selected from the group consisting of carboxylic esters, carboxylic acids, carboxylic amides, imides, amines, phosphoric acid derivatives, phosphonic acid derivatives, dithiophosphate esters, ethers, hydroxyls, carbonates, thio derivatives thereof, and heterocyclic groups.
DETAILS OF THE INVENTION
Herein certain terms are used, some of them relating to lubricants. Lubricant technology is well known in general, see for instance E. R. Booser, Ed.,
CRC Handbook of Lubrication,
Vol. II, CRC Press, Inc., Boca Raton, Fla., U.S.A., (1983), p. 229-315; D. Klamann in B. Elvers, et al., Ed.,
Ullmann's Encyclopedia of Industrial Chemistry,
Vol. A15, VCH Verlagsgesellschaft mbH, Weinheim, Germany (1990), p. 424-511; R. M. Mortimer, et al., Ed.,
Chemistry and Technology of Lubricants,
VCH Publishers, New York, 1992; all of which are hereby included by reference. Herein the following terms are defined as:
A lubricant base is a material that is the majority of the component of the lubricant system, and which reduces friction and/or wear between the moving components being lubricated, and may also have other useful functions. Useful lubricant bases include petroleum derived (sometimes also called mineral) lubricants, synthetic hydrocarbons, polyether oils, carboxylic esters, phosphoric acid esters, silicone containing oils, and halogenated hydrocarbons and halocarbons. Petroleum derived and synthetic hydrocarbon lubricant bases are preferred and petroleum derived lubricant bases are especially preferred.
A lubricant additive is a chemical which improves the wear-reducing ability or decreases the friction of a lubricant base when a state of hydrodynamic lubrication cannot be maintained. Common lubricants provide for a liquid film between parts moving with respect to one another. This is called hydrodynamic lubrication. As long as a full hydrodynamic liquid film is maintained between the parts, wear will be minimized and friction will be determined entirely by the properties of the fluid film. Hydrodynamic lubrication is often difficult to achieve and maintain in practice. Many lubricants, such as mineral oils, found to be highly effective under hydrodynamic lubricating conditions exhibit seriously degraded performance when conditions depart therefrom. It is for this reason that lubricant additives are necessary. Addition of lubricant additives to lubricant bases results in lubricant compositions which exhibit excellent lubricating performance over a wide range conditions in use. The present invention is directed to a particular class of compositions, hereinbelow described, which have surprisingly been found to be highly effective as lubricant additives.
By an organic compound is meant a compound which contains at least one hydrogen atom bound directly to a carbon atom.
By a functional group is meant any group or moiety containing an element other than carbon, hydrogen and fluorine. These are sometimes called “polar head groups”. See for instance J. A. Crawford, et al., in R. M. Mortimer, et al., Ed.,
Chemistry and Technology of Lubricants,
VCH Publishers, New York, 1992, p. 165, and A. J. Groszek,
Interdisciplinary Approach to Lubricant Technology
, NASA SP-318 1973, p. 477-525, both of which are hereby included by reference.
By adsorbed on the metal surface is meant that the functional group concerned (and hence the compound which contains that functional group) is attracted to a metal surface with energies in excess of ordinary Van der Waals forces, as exhibited by hydrocarbons such as n-alkanes. The molecule which contains the functional group is often a so-called amphiphile, which has the functional group, and another part of the molecule is compatible with the lubricant base being used. The use of these amphiphiles as lubricant additives and associated topics are also discussed in M. Salmeron, Chemtech, September 1998, p. 17; H. A. Spikes, Langmuir, vol. 12, p. 4567 (1996); M. K. Chaudry, Current Opinion Colloid Interfacial Sci., vol. 2, p. 65 (1997), all of which are hereby included by reference. This adsorption may be measured by adsorbing the compound containing the functional group on the metal surface from a solution in n-alkane, as described in A. J. Groszek,
Interdisciplinary Approach to Lubricant Technology
, NASA SP-318 1973, p. 477-525. Such forces can include covalent or coordinative bonding, electrostatic or coulombic interactions, and hydrogen bonding. This metal surface herein includes not only the metals themselves, but any other lay
Beatty Richard Paul
Morken Peter Arnold
E. I. du Pont de Nemours and Company
Medley Margaret
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