JP2007277543A - Grease composition and additive for improving life of bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition, a method for the use of a grease composition, an additive for a grease composition, and apparatuses and vehicles containing a grease composition for improving fretting abrasion resistance. <P>SOLUTION: The grease composition contains a completely formulated grease base and an active amount of a fretting abrasion suppressing agent. The fretting abrasion suppressing agent is a non-metallic oil-soluble phosphorus-containing amine sulfide salt and is used in an amount sufficient for lowering the weight loss caused by fretting abrasion to a level lower than about 20 mg. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present disclosure relates to a lubricating grease composition for rolling and rotating bearings and uses thereof, more specifically, continuity impacts caused by external vibrations that occur during transportation, drop impacts caused by vibrations and drops during transportation, etc. Relates to an improved lubricating grease composition which improves resistance to fretting caused by The composition is particularly useful for bearings that have not been used and have poor lubrication.

  Fretting wear (also known as “fretting corrosion” or “false”, as seen in wheel bearings in automobiles transported by rail cars or roller bearings for industrial equipment stored in areas subject to vibration from other operating equipment. "Brinelling" (also known as "false rinelling") is caused by bearing vibration. Fretting wear can cause initial bearing failure immediately after starting the vehicle or equipment. This type of wear phenomenon is caused by a short arc of bearing vibration, impedes sufficient lubricant flow to the bearing section and traps wear debris near the bearing. Corrosive oxidation also occurs on the bearing surface and can exacerbate bearing corrosion and damage. All of these conditions, in turn, increase the degree of bearing wear.

  Frequent wear occurs mainly in bearings that have not been operating for a long time, since the periodic operation of the bearings provides protective lubricant around the bearings and tends to wash away wear debris from around the bearings. Fretting wear is an industry standard test ASTM D-4170-97 called “Standard Test Method for Fretting Wear Prevention Performance with Lubricating Grease” which measures the weight loss after a specimen is left under vibration for 20 hours. (2002). Some key specifications in the grease industry require low fretting wear values as determined by the aforementioned ASTM D-4170 test. Such specifications include NLGI's GC-LB specification (fretting wear <10 mg), GM's LS2 specification for “high temperature”, “high speed bearing”, and “multipurpose” greases (fretting wear <10 mg), and This includes, but is not limited to, GM's LS2 specification for “fretting and corrosion inhibition” grease (fretting wear <2 mg). Accordingly, there continues to be a need for improved grease formulations that meet industry specifications for fretting wear without adversely affecting other important properties of the grease.

  In view of the continuing need for improved leasing compositions, exemplary embodiments of the present disclosure include grease compositions, additives for grease compositions, usage of grease compositions, and fretting wear performance. Provided are a device and a vehicle that contain a grease composition for improving the performance. The grease composition includes a fully formulated grease base and an effective amount of fretting wear reducing agent. A fretting wear reducing agent is a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt used in an amount sufficient to reduce the weight loss due to fretting wear to less than about 20 milligrams.

In another exemplary embodiment, a method for reducing fretting wear in a bearing is provided. In this method, a grease composition is added to the bearing. The grease composition includes an effective amount comprising a fully formulated grease base and a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams. And additives.

  In yet another exemplary embodiment of the present disclosure, a fully formulated grease base and a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams. A wheel bearing for a vehicle is provided that is in contact with an effective amount of an additive.

  In another exemplary embodiment of the present disclosure, an additive for grease is provided that reduces the weight loss properties of grease due to fretting wear. The additive is a metal-free and oil-soluble phosphorus-containing sulfurized amine salt component, and when a predetermined amount of the additive is added to the grease, a grease with a weight loss due to fretting wear of less than about 20 milligrams is obtained.

  The additives for grease compositions disclosed herein are highly compatible with grease compositions. Thus, exemplary embodiments of the present disclosure allow for significant changes in other performance characteristics (such as extreme pressure characteristics and corrosion protection performance) of grease formulations that may be reduced by competition with active ingredients on the surface. While enhancing the fretting wear prevention performance, the flexibility in formulating grease can be increased. Also, depending on the formulation, the wear resistance, extreme pressure properties, and corrosion protection performance of the grease formulation may be significantly enhanced by the additive.

  Grease formulations improved with the additives described herein include a variety of conventional mineral and synthetic oil based grease compositions. Such compositions include, but are not limited to, metal complex thickeners, alkali metal complex thickeners, urea compound thickeners, and the like. A fully formulated grease formulation may include other additives useful for obtaining specific performance characteristics in addition to the additives described herein.

A wide variety of base oils are used to prepare the grease compositions described herein. For example, the base oil is selected from any conventionally used mineral oil, synthetic hydrocarbon oil, or synthetic ester oil. These oils typically have a viscosity at 40 ° C. of about 5 cSt to about 10,000 cSt, but typical applications require oils having a viscosity at 40 ° C. of about 10 cSt to about 1,000 cSt. The mineral oil base stock used is any of the conventional refined base stocks obtained from paraffinic, naphthenic and mixed crudes. Synthetic oil base stocks used include esters of dibasic acids such as di-2-ethylhexyl sebacate; esters of glycols such as the C ₁₃ -oxide diester of tetraethylene glycol; or 1 mole of sebacic acid, Complex esters such as those formed from 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid are included. Other synthetic oils used include synthetic hydrocarbons such as polyalphaolefins; alkylate residues obtained from alkylbenzenes, alkylation of benzene with tetrapropylene, or benzene with ethylene and propylene copolymers; reacting an oxo alcohol with ethyl carbonate - C ₈ to form, for example, half esters; polyglycol oils as obtained by condensing in propylene oxide, for example butyl alcohol; polysiloxanes, silicone oils such as methyl polysiloxane Carbonic acid esters; and the like, such as products obtained by subsequent reaction of the latter with tetraethylene glycol. Other suitable synthetic oils include polyphenyl ethers, such as those having from about 3 to about 7 ether linkages and from about 4 to about 8 phenyl groups. (See U.S. Pat. No. 3,424,678, column 3.) The amount of base oil in the grease composition also varies over a wide range, but is generally, for example, from about 75 wt.% To about 95 wt. , Mostly consisting of a grease composition.

As described herein, the grease composition also includes a small amount of simple soap.
Le soap or complex soap thickener, or organic thickener, or inorganic clay thickener. These types of greases include alkali metal or alkaline earth metal simple and complex soap greases, metallic simple and complex greases, as well as polyurea greases, organic clay greases, and bentonite clays / swellability. Clay type thickeners are included, but are not limited to these.

  For example, as a main use of a composite soap grease of alkali metal or alkaline earth metal, use as a grease for bearings (for example, automobiles and electric appliances), particularly sealed bearings is known. Sealed bearing greases are pre-defined for many requirements including bearing life extension, high temperature performance, dropping point, oil separation, oxidative stability, fretting anti-wear performance, and low noise. Must meet the requirements. However, even with extended long service and improved high temperature performance, such greases often have higher noise characteristics than alkali metal or alkaline earth metal single greases. There is.

Useful thickeners for alkali metal or alkaline earth metal composite soap greases contain two, generally three alkali metal or alkaline earth metal components. The first component is at least one alkali metal or alkaline earth metal soap of a hydroxy fatty acid, such as a C ₁₂ to C ₂₉ hydroxy acid. The second component is (i) a C ₂ to C ₁₂ aliphatic or cycloaliphatic dicarboxylic acid (or their alkyl esters such as C ₁ to C ₁₉ , eg C ₁ to C ₄ ); or (ii ) C ₃ to C ₂₄ hydroxy carboxylic acids (or their alkyl esters such as C ₁ to C ₁₉ , eg C ₁ to C ₄ ), wherein the hydroxy group is separated from the carboxyl group by no more than 6 carbon atoms; Alternatively, a mixture thereof is selected from alkali metal or alkaline earth metal compounds.

Useful hydroxy fatty acids include hydroxystearic acid, hydroxyricinoleic acid, hydroxybehenic acid, and hydroxypalmitic acid. A particularly useful hydroxyl fatty acid is hydroxystearic acid. The second alkali metal or alkaline earth metal compound is suitably a C ₆ to C ₁₀ aliphatic dicarboxylic acid, more typically azelaic acid or sebacic acid, especially azelaic acid, or any of these Ester. The C ₃ to C ₂₄ hydroxycarboxylic acid is typically lactic acid, salicylic acid, or other hydroxybenzoic acid, more suitably salicylic acid or any of the esters mentioned above. The amount of alkali metal or alkaline earth metal soap complex thickener in the grease composition is from about 5% to about 20% by weight. The weight ratio of hydroxy fatty acid to aliphatic dicarboxylic acid and / or hydroxycarboxylic acid is typically from about 10: 0.5 to about 10:15, such as from about 10: 1.5 to about 10: 6.

  Other thickeners include acetic acid / calcium stearate (US Pat. No. 2,197,263); acetic acid / barium stearate (US Pat. No. 2,564,561); caproic acid / acetic acid / calcium stearate complex ( US Pat. No. 2,999,065); acetic acid / calcium caproate (US Pat. No. 2,999,066); and low molecular weight (1-6 carbon atoms), medium molecular weight (7-carbon atoms) 12) acids, and high molecular weight (13-18 carbon atoms) acids, and salts and salts and soap complexes, such as calcium salts and soaps of nut oil acids, These are not limited.

Another class of thickeners includes substituted ureas, phthalocyanines, indanthrene, perylimide, pyromellitic imide, and dyes including ammelin.

  Examples of metal soaps that are effective thickeners for grease compositions according to the disclosed examples include aluminum laurate, aluminum oleate soap, aluminum stearate, aluminum stearate benzoate , Aluminum oleate, aluminum 12-hydroxystearate, aluminum stearate, aluminum toluate, aluminum naphthenate, aluminum benzoate, hydrogenated rosin, sulfonic acid, benzoic acid Aluminum, aluminum azelaate stearate, aluminum stearate benzoate phosphate, hydro Aluminum stearate benzoate, lithium laurate, lithium stearate, lithium benzoate stearate, lithium oleate, lithium 12-hydroxystearate benzoate, lithium toluate stearate, lithium naphthenate benzoate, benzoic acid Lithium hydrogenated rosin, lithium sulfonate benzoate, lithium azelate stearate, lithium stearate benzoate phosphate, lithium hydroxystearate benzoate and the like.

  Metal complex soaps or alkali metal or alkaline earth metal complexes may be present in the grease in an amount sufficient to thicken the oil to the grease concentration. Broadly speaking, the amount of soap or alkali metal complex is from about 1% to about 30% by weight of the grease. Generally, however, from about 5% to about 20%, such as from about 10% to about 15%, by weight thickener is used to increase the viscosity of the grease.

  In addition to the ingredients already mentioned, the fully formulated grease composition also contains corrosion inhibitors, antiwear agents, pour point depressants, adhesives, extreme pressure additives, thickeners, antioxidants, A small amount of other additives are included, including but not limited to rust inhibitors, dyes, and the like. Such components are present in the fully formulated grease composition in an amount from about 1% to about 10% by weight.

  An important component of the grease composition according to the present disclosure is an effective amount of fretting wear reducing agent. Oil-soluble metal-free salts of phosphorus-containing compounds are particularly suitable additives for reducing fretting wear. Most oil-soluble metal-free phosphorus-containing compounds are partially or fully esterified acids of phosphorus. Such compounds include, for example, phosphates, phosphites, phosphonates, phosphonites, and various sulfur analogs thereof. Examples include monohydrocarbyl phosphite; monohydrocarbyl phosphate; monohydrocarbyl monothiophosphite, monohydrocarbyl dithiophosphite, monohydrocarbyl trithiophosphite, and monohydrocarbyl tetrathiophosphite; monohydrocarbyl monothiophosphate; Monohydrocarbyl dithiophosphate, monohydrocarbyl trithiophosphate, and tetrathiophosphoric acid; dihydrocarbyl phosphite; dihydrocarbyl phosphate; dihydrocarbyl monothiophosphite, dihydrocarbyl dithiophosphite, dihydrocarbyl trithiophosphite Dihydrocarbyl tetrathiophosphite; dihydrocarbyl monothiophosphate, dihydrocarbyl dithiophosphate, dihydrocarbyl trithiophosphate, dihydrocarbyl tetrathio Trihydrocarbyl phosphate; trihydrocarbyl phosphate; trihydrocarbyl monothiophosphite, trihydrocarbyl dithiophosphite, trihydrocarbyl trithiophosphite, and trihydrocarbyl tetrathiophosphite Trihydrocarbyl monothiophosphate, trihydrocarbyl dithiophosphate, trihydrocarbyl trithiophosphate, and trihydrocarbyl tetrathiophosphate; various hydrocarbyl phosphonates and thiophosphonates; various hydrocarbyl phosphonites and thiophosphonites; and polyphosphorus Similar oil-soluble derivatives of acids and polythiophosphoric acids; and many others. Tricresyl phosphate, tributyl phosphite, triphenyl phosphite, tri- (2-ethylhexyl) phosphate, dihexylthiophosphite, diisooctylbutyl phosphonate, tricyclohexyl phosphate, diphenyl cresyl phosphate, Tris (2-butoxyethyl) phosphite, diisopropyl dithiophosphate, tris (tridecyl) tetrathiophosphate, tris (2-chloroethyl) phosphate and similar compounds are a few specific examples of such compounds.

Particularly preferred metal-free phosphorus-containing compounds for use herein are (a) oil-soluble amine salts of monohydrocarbyl monothiophosphoric acid, (b) oil-soluble amine salts of dihydrocarbyl monothiophosphoric acid, and (c) (a ) And (b). Such compounds include monohydrocarbyl phosphites and / or dihydrocarbyl phosphites and sulfur or sulfur, dihydrocarbyl polysulfides, sulfurized olefins, sulfurized fatty acid esters, trithiones, sulfurized thienyl derivatives, sulfurized terpenes, C ₂ -C ₈ mono It is made by reacting sulfurized oligomers of olefins, and sulfurized Diels-Alder adducts and one or more primary or secondary amines and other active sulfur-containing compounds. Such a reaction tends to be an extremely exothermic reaction, and may not be fully controlled if not performed correctly. Suitable methods for forming the amine salts described above include (i) one or more dihydrocarbyls such as dialkyl hydrogen phosphites while stirring the formed mixture at a rate that does not exceed about 60 ° C. Adding hydrogen phosphite to one or more excess active sulfur-containing materials, such as branched sulfurized olefins (eg, isobutylene, diisobutylene, triisobutylene, etc.), (ii) during this temperature, One or more aliphatic primary or secondary amines having from about 8 to about 24 carbon atoms in each molecule, eg, one or more, while stirring the mixture formed at a rate not exceeding about 60 ° C. And (iii) maintaining the temperature of the resulting stirred reaction mixture between about 55 ° C. and about 60 ° C. until the reaction is substantially complete. Etc. and appropriate processes are involved. Another suitable method for producing these amine salts is to add all three reactants simultaneously to the reaction zone at an appropriate rate, controlling the temperature not to exceed about 60 ° C.

  The amount of fretting wear reducing agent in the fully formulated grease composition is from about 0.1% to about 10% by weight. An effective amount of fretting wear reducing agent is from about 0.5% to about 5% by weight, based on the total weight of the grease composition.

The following ratio-limiting examples are provided to illustrate aspects of the disclosed examples. In this example, a fretting wear reducing agent was added to two commercially available grease compositions. The first grease composition comprises a large amount of paraffinic base oil and a small amount of aluminum stearate benzoate complex thickener, antimonin dithiocarbamate, molybdenum disulfide, and / or an adhesive, and a rust inhibitor / antioxidant. From now on, it is called “aluminum complex grease”. The second grease composition contains a large amount of base oil and a small amount of hydroxyl lithium stearate complex, zinc dialkyldithiophosphate, and diphenylamine, and is hereinafter referred to as “lithium complex grease (1)”. The third grease composition includes an approximately 4.5 wt.% Additive package containing zinc dialkyldithiophosphate, sulfurized isobutylene, corrosion inhibitor, and several antioxidants. This is referred to as “complex grease (2)”. A fretting wear reducing agent is a diflate made by sulfurization of dibutyl hydrogen phosphite in the presence of oleylamine and n-octylamine, as generally described in US Pat. No. 5,328,619. It is an oil-soluble mixed amine salt of hydrocarbyl monothiophosphate. In each experiment, weight loss due to fretting wear was determined by the industry standard test ASTM D-4170-97 (2002), which measures the amount of weight loss after placing a specimen under vibration conditions for 20 hours.
(Example 1)

  As seen in Experiment 3-5 in the table above, the aluminum complex grease containing 0.5 wt% to 2.0 wt% additive was identical without the additive illustrated in Experiments 1 and 2. Showed a dramatic reduction in fretting wear (weight loss from 4.2 mg to 19.5 mg) compared to the grease (weight loss from 22.4 mg to 30 mg). Lithium complex grease (1) also showed a significant reduction in fretting wear, with a weight loss of 9.3 mg to 7.2 mg, but not as drastically with 2 wt% additive. However, the lithium complex grease (2) has a weight loss of about 73% when 0.5 wt.% Fretting wear reducer is used compared to Experiment 1 where no fretting wear reducer is used. Showed a decline.

Fretting wear reducing agents are also effective in reducing grease corrosion and increasing extreme pressure (EP). In the following examples, the above grease formulations were subjected to a four ball extreme pressure test and / or a load four ball wear test for weld point determination. The lithium complex grease (2) was subjected to a bearing corrosion test. The results of these tests are shown in the following table.
(Example 2)

  In Table 2 above, the weld point of aluminum complex grease without fretting wear reducer was between 230 kg and 250 kg, whereas by adding 1 wt% to 2 wt% fretting wear reducer. The weld point increased to 260 kg. In addition, 0.5 wt% fretting wear reducing agent improved the weld point of the lithium complex grease (2) from 300 kg to 310 kg. The fretting wear reducer also improved the four-ball wear scar of the lithium complex grease (1) by about 15% over the same grease without the fretting wear reducer.

  In addition, a 48 hour bearing compared to a bearing using a lithium complex grease (2) containing a fretting wear reducing agent and a bearing using a lithium complex grease (2) containing no fretting wear reducing agent. The corrosion test was conducted at 52 ° C. If the lithium complex grease (2) does not contain a fretting wear reducing agent, only one of the three bearings was not corroded and this was considered a failure by the ASTM D-1743 test. It is. However, when 0.5% by weight of the fretting wear reducing agent was contained in the lithium complex grease (2), no corrosion was observed in three of the three bearings, and an acceptable state was obtained.

  Although the above examples showed a significant reduction in fretting wear in aluminum complex and lithium complex greases, the additive is considered suitable for reducing the fretting wear of any type of grease. Thus, vehicle wheel bearings; rotating and sliding equipment bearings; electrical appliances; various electronic information recording and decoding instruments such as hard disk drives, video tape recorders, laser printers, compact disk drives, digital video disk drives, and unused or In order to reduce the fretting wear of rolling bearings used in other applications where fretting wear exists due to insufficient vibration and / or lubrication of moving parts, the additives described herein may be The contained grease can be used.

  Numerous U.S. patents are referenced throughout the specification. All such references are fully expressly included in this disclosure as if fully set forth herein.

  The embodiments described above can vary considerably in their implementation. Accordingly, the examples are not intended to be limited to the specific illustrations described above. Rather, the above embodiments are within the spirit and scope of the appended claims, including the legally available scope.

This patent owner does not intend to make any disclosed embodiments public, and any modifications or changes disclosed may not be included to some extent literally within the scope of the claims, Are also considered to be part of this specification by the doctrine of equivalents.
The main features and aspects of the present invention are as follows.
1. A grease comprising a fully formulated grease base and an effective amount of an additive comprising a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams. Composition.
2. The grease composition of claim 1, wherein the weight loss due to fretting wear is less than about 10 milligrams.
3. 2. The grease composition according to 1 above, wherein the metal-free and oil-soluble phosphorus-containing amine salt is obtained from a sulfur source and dihydrocarbyl phosphite.
4). The grease composition of claim 3, wherein the dihydrocarbyl phosphite comprises a dialkyl hydrogen phosphite having from about 4 to about 25 carbon atoms in each alkyl group.
5). Among the group consisting of sulfur, dihydrocarbyl polysulfide, sulfurized olefin, sulfurized fatty acid ester, trithione, sulfurized thienyl derivative, sulfurized terpene, sulfurized oligomer of C ₂ -C ₈ monoolefin, and sulfurized Diels-Alder adduct 4. The grease composition according to the above item 3, which is selected from
6). The grease composition of claim 1, wherein the amine salt amine comprises an aliphatic primary or secondary amine containing from about 8 to about 24 carbon atoms per molecule.
7). The grease composition of claim 1, wherein the fully formulated grease base comprises from about 0.1 wt% to about 5 wt% additive.
8). A wheel bearing comprising the grease composition according to 1 above.
9. A movable part having a bearing surface, the bearing surface being lubricated with the grease composition described in 1 above.
10. An apparatus comprising one or more bearings and comprising the grease composition of claim 1 above.
11. An electronic information recording and decoding device comprising a ball composition and ball-and-roller bearings and comprising the grease composition of claim 1 above.
12 The bearing includes a fully formulated grease base and an additive comprising a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt in an amount sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams. A method of reducing fretting wear in a bearing comprising adding a grease composition.
13. 13. The process of claim 12, wherein the metal-free and oil-soluble phosphorus-containing amine salt is obtained from a sulfur source and dihydrocarbyl phosphite.
14 14. The method of claim 13, wherein the dihydrocarbyl phosphite comprises a dialkyl hydrogen phosphite having from about 4 to about 25 carbon atoms in each alkyl group.
15. The sulfur source is selected from the group consisting of sulfur, dihydrocarbyl polysulfides, sulfurized olefins, sulfurized fatty acid esters, trithiones, sulfurized thienyl derivatives, sulfurized terpenes, sulfurized oligomers of C2-C8 monoolefins, and sulfurized Diels-Alder adducts. 14. The method according to 13 above, wherein
16. 13. The method of claim 12, wherein the amine salt amine comprises an aliphatic primary or secondary amine containing from about 8 to about 24 carbon atoms per molecule.
17. 13. The method of claim 12, wherein the fully formulated grease base includes from about 0.1% to about 5% by weight additive.
18. 13. The method of claim 12, wherein the weight loss due to fretting wear is less than about 10 milligrams.
19. Vehicle comprising a fully formulated grease base and an effective amount of an additive comprising a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams Wheel bearings.
20. 20. The vehicle wheel bearing of claim 19, wherein the weight loss due to fretting wear is less than about 10 milligrams.
21. 20. The vehicle wheel bearing of claim 19, wherein the metal-free and oil-soluble phosphorus-containing amine salt is obtained from a sulfur source and dihydrocarbyl phosphite.
22. 22. The vehicle wheel bearing of claim 21, wherein the dihydrocarbyl phosphite comprises a dialkyl hydrogen phosphite having from about 4 to about 25 carbon atoms in each alkyl group.
23. Among the group consisting of sulfur, dihydrocarbyl polysulfide, sulfurized olefin, sulfurized fatty acid ester, trithione, sulfurized thienyl derivative, sulfurized terpene, sulfurized oligomer of C ₂ -C ₈ monoolefin, and sulfurized Diels-Alder adduct 22. The vehicle wheel bearing according to the item 21, which is selected from the above.
24. 20. The vehicle wheel bearing of claim 19, wherein the amine of the amine salt comprises an aliphatic primary or secondary amine containing from about 8 to about 24 carbon atoms per molecule.
25. 20. The vehicle wheel bearing of claim 19, wherein the fully formulated grease base comprises from about 0.1% to about 5% by weight additive.
26. Reduces the weight loss characteristics due to the fretting wear of grease and adds a certain amount to the grease, so that the weight loss due to the fretting wear of the grease is less than about 20 milligrams and is essentially metal-free and oil-soluble phosphorus. Additive for grease consisting of a sulfurized amine salt component.
27. 24. The additive of claim 23, wherein the weight loss due to fretting wear of grease containing the additive is less than about 10 milligrams.
28. 27. The additive according to 26, wherein the metal-free and oil-soluble phosphorus-containing amine salt is obtained from a sulfur source and dihydrocarbyl phosphite.
29. 29. The additive of claim 28, wherein the dihydrocarbyl phosphite comprises a dialkyl hydrogen phosphite having from about 4 to about 25 carbon atoms in each alkyl group.
30. Among the group consisting of sulfur, dihydrocarbyl polysulfide, sulfurized olefin, sulfurized fatty acid ester, trithione, sulfurized thienyl derivative, sulfurized terpene, sulfurized oligomer of C ₂ -C ₈ monoolefin, and sulfurized Diels-Alder adduct 29. The additive according to 28 above, which is selected from
31. 27. A grease comprising from about 0.1% to about 5% by weight of the additive of claim 26.

Claims (8)

  A grease comprising a fully formulated grease base and an effective amount of an additive comprising a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams. Composition.   The grease composition of claim 1, wherein the dihydrocarbyl phosphite comprises a dialkyl hydrogen phosphite having from about 4 to about 25 carbon atoms in each alkyl group. Among the group consisting of sulfur, dihydrocarbyl polysulfide, sulfurized olefin, sulfurized fatty acid ester, trithione, sulfurized thienyl derivative, sulfurized terpene, sulfurized oligomer of C ₂ -C ₈ monoolefin, and sulfurized Diels-Alder adduct The grease composition according to claim 1, wherein the grease composition is selected from:   A wheel bearing comprising the grease composition according to claim 1.   The bearing includes a fully formulated grease base and an additive comprising a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt in an amount sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams. A method of reducing fretting wear in a bearing comprising adding a grease composition.   6. The method of claim 5, wherein the amine of the amine salt comprises an aliphatic primary or secondary amine containing from about 8 to about 24 carbon atoms per molecule.   Vehicle comprising a fully formulated grease base and an effective amount of additive comprising a metal-free, oil-soluble, phosphorus-containing sulfurized amine salt sufficient to reduce weight loss due to fretting wear to less than about 20 milligrams Wheel bearings.   Reduces the weight loss characteristics due to the fretting wear of grease and adds a certain amount to the grease, so that the weight loss due to the fretting wear of the grease is less than about 20 milligrams and is essentially metal-free and oil-soluble phosphorus. Additive for grease consisting of a sulfurized amine salt component.