Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic sulfur compound – wherein the sulfur is single bonded...
Reexamination Certificate
1999-07-06
2002-10-22
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic sulfur compound, wherein the sulfur is single bonded...
C508S435000, C508S436000, C508S437000, C508S441000
Reexamination Certificate
active
06468946
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to lubricating compositions which provide improved antiwear and thermal stability properties. The lubricating compositions comprise a combination of (A) at least one di or trihydrocarbyl phosphite, (B) at least one reaction product of a di or trihydrocarbyl phosphite and sulfur or a source of sulfur; at least one di or trihydrocarbyl monothiophosphate; or salt thereof, and (C) at least one salt of a hydrocarbyl phosphoric acid ester.
BACKGROUND OF THE INVENTION
Lubricating compositions are used to prevent damage to machinery under operating conditions. Especially under boundary lubrication conditions, a lubricant must act to minimize harmful metal-to-metal contact. Often additives are useful at providing protection under boundary lubricating condition but sometimes these additive adversely affect other performance characteristics. For instance, a lubricant must still provide protection under high speed, shock loading condition, while not be corrosive to copper and other soft metals.
Phosphorus compounds have been used in lubricants to provide antiwear and antioxidation properties to lubricants. Phosphorus compounds generally protect metal from the effects of low speed and heavy load conditions. When the total level of phosphorus provided by the lubricant is below 0.1% by weight there have often been problems with the ability of the lubricant to provide the needed antiwear protection. In the past boron compounds, such as borated dispersants, provide thermal stability and cleanliness. It is desirable to provide additives for lubricants which provide improved antiwear properties and thermal stability.
SUMMARY OF THE INVENTION
This invention relates to a lubricating composition comprising a major amount of an oil of lubricating viscosity and (A) a di or trihydrocarbyl phosphite, (B) at least one reaction product of a di or trihydrocarbyl phosphite and sulfur or a source of sulfur; at least one di or trihydrocarbyl monothiophosphate; or salt thereof, and (C) a salt of a hydrocarbyl phosphoric acid ester. In one embodiment, the lubricant composition contains less than 0.1% phosphorus or less than about 0.75% borated dispersant. This combination of phosphorus compounds provides antiwear and thermal stability to lubricants, even at low phosphorus levels. The lubricating compositions containing the combination of the phosphorus compounds has low corrosivity to copper and low odor as well.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The term “hydrocarbyl” includes hydrocarbon as well as substantially hydrocarbon groups. Substantially hydrocarbon describes groups which contain heteroatom substituents that do not alter the predominantly hydrocarbon nature of the substituent. Examples of hydrocarbyl groups include the following:
(1) hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl) and alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, aromatic-, aliphatic-and alicyclic-substituted aromatic substituents and the like as well as cyclic substituents wherein the ring is completed through another portion of the molecule (that is, for example, any two indicated substituents may together form an alicyclic radical);
(2) substituted hydrocarbon substituents, i.e., those substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent; those skilled in the art will be aware of such groups (e.g., halo (especially chloro and fluoro), hydroxy, mercapto, nitro, nitroso, sulfoxy, etc.);
(3) heteroatom substituents, i.e., substituents which will, while having a predominantly hydrocarbon character within the context of this invention, contain an atom other than carbon present in a ring or chain otherwise composed of carbon atoms (e.g., alkoxy or alkylthio). Suitable heteroatoms will be apparent to those of ordinary skill in the art and include, for example, sulfur, oxygen, nitrogen and such substituents as, e.g. pyridyl, furyl, thienyl, imidazolyl, etc.
In general, no more than about 2, preferably no more than one heteroatom substituent will be present for every ten carbon atoms in the hydrocarbyl group. Typically, there will be no such heteroatom substituents in the hydrocarbyl group. Therefore, the hydrocarbyl group is hydrocarbon.
Generally the total phosphorus for the lubricant is determined by the amount of all phosphorus components added to the lubricant. The amount of phosphorus in the lubricating composition is sufficient to provide a pass result in the ASTM L-37 test. The total phosphorus is usually less than about 0.1%, or less than 0.09%, or less than about 0.08% by weight. In one embodiment, the phosphorus compounds of the present invention are present at phosphorus contents of less than about 0.07, or less than about 0.06% by weight phosphorus.
As described above the lubricating composition comprise a combination of (A) at least one di or trihydrocarbyl phosphite, (B) at least one reaction product of a phosphite and sulfur or a source of sulfur; at least one di or trihydrocarbyl monothiophosphate; or salt thereof, and (C) at least one salt of a hydrocarbyl phosphoric acid ester. Each component of the combination may be independently present in an amount to provide from about 0.01% to about 0.06%, or from about 0.012% to about 0.05%, or from about 0.018% to about 0.04% by weight phosphorus to the lubricant. Here, as well as elsewhere in the specification and claims, the range and ratio limits may be combined. In one embodiment, each component is present in substantially equal phosphorus proportions. In another embodiment, each component is independently present in an amount from about 0.05% to about 2%, or from about 0.08% to about 1%, or from about 0.1°% to about 0.6% by weight.
As described herein and in the appended claims, it is understood that any element listed within a genus or list may be excluded from the claims.
(A) Phosphites
As described above the lubricating compositions, concentrates, and greases contain at least one phosphite. The phosphite may be a di- or trihydrocarbyl phosphite. Preferably each hydrocarbyl group contains from 1 to about 24 carbon atoms, or from 1 to about 18 carbon atoms, or from about 2 to about 8 carbon atoms. Each hydrocarbyl group may be independently alkyl, alkenyl, or aryl, preferably alkyl or alkenyl. When the hydrocarbyl group is an aryl group, then it contains at least about 6 carbon atoms; preferably about 6 to about 18 carbon atoms. Examples of the alkyl or alkenyl groups include propyl, butyl, hexyl, heptyl, octyl, oleyl, linoleyl, stearyl, etc. Examples of aryl groups include phenyl, naphthyl, heptylphenol, etc. Preferably each hydrocarbyl group is independently propyl, butyl, pentyl, hexyl, heptyl, oleyl or phenyl, more preferably butyl, oleyl or phenyl and more preferably butyl or oleyl. In one embodiment, the phosphite is an alkyl or alkyenyl, preferably an alkyl phosphite. In another embodiment, the lubricating compositions are free of phosphites with hydrocarbyl groups that are aryl groups. One method of preparing phosphites includes reacting a lower (C
1-8
) Phosphites and their preparation are known and many phosphites are available commercially. Particularly useful phosphites are dibutyl hydrogen phosphite, dioleyl hydrogen phosphite, di(C
14-18
) hydrogen phosphite, and triphenyl phosphite.
In another embodiment, the phosphite is premixed with a overbased metal salt of an organic acid, wherein the equivalents of overbased metal salt, based on total base number to the equivalents of phosphite (A) based on phosphorus atoms is at least one. The inventors have discovered that by pre-mixing the phosphite in the overbased metal salt of an acidic organic compound, the hydrostability of the phosphite is improved. Overbased metal compositions are characterized by having a metal content in excess of that which would be present according to the stoichiometry of the metal and the acidic organic compound. The amount of excess metal is commonly expressed in metal ratio. The ter
Esposito Michael F.
Johnson Jerry D.
The Lubrizol Corporation
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