(2) Description of the Related Art For many machines, the conduction of electrical charge through rotating joints, bearings, journal, sleeves and the like is necessary to prevent buildup of static charge between parts of the machine, or between the machine and a wcrkpiece. Typically, such joints must be lubricated and conventional lubricants such as oils and greases have such low electrical conductivity that static charges cannot be dissipated through the joint.

This has led to the use of such devices as brushes, split-sleeves, mercury contacts and other such mechanical and liquid contactors to carry off the charge before harmful discharges can occur. However, these devices at least require maintenance and repair and at worst can fail, leaving the machine unprotected.

Conductive lubricants have been devised, but most of these are conventional lubricants that are made conductive by the addition of electrically conductive materials such as fine metal powders or graphite. Among

the problems associated with such lubricants are those associated with the relatively high levels of such conducting materials required to provide the minimum conductivity necessary for anti-static applications (about 10-8 S/cm). Such high levels of conducting materials can result in reduction of the lubricating effectiveness of the compound and can sometimes result in separation of particles of the conductive material from the lubricant. When the lubricant is used in very sensitive applications, such as the lubrication of computer hard drives, the presence of such hard or unplasticized particles can injure the drive and is unacceptable. If higher levels of conductivity are required, such particulate-containing lubricants may not be effective. Thus, it would be useful to provide a conductive lubricant that is free of hard or unplasticized solid particles, such as metals or carbon, that can separate from the bulk of the lubricant and cause damage to sensitive electrical or mechanical parts.

Moreover, in many applications where conductive lubricants would be useful, the joints and bearings are so small that even small amounts of corrosion could be a serious problem. Thus, it is also desirable that the lubricant protect the lubricated joint from corrosion.

It is well known that intrinsically conductive polymers can protect metals from corrosion and also have significantly high electrical conductivity. As used herein, the terms"intrinsically conductive polymer ", or "ICP"are to be understood to mean any polymer having a polyconjugated n electron system and which is electrically conductive in at least one valence state.

By"electrically conductive"it is meant that the material has a volumetric electrical conductivity of at least about 10'8 S/cm. Examples of such ICP's are substituted and unsubstituted polyaniline, polypyrrole, polythiophene and polyacetylene, among others.

Despite the anticorrosive and conductive properties of ICP's, it is known that many types of ICP's are not soluble in, or do not form stable mixtures with conventional paraffinic lubricants. ICP's are known that are soluble in nonpolar organic solvents. However, most such solvents are of low viscosity and have little or no lubricating properties. They are also relatively volatile when compared with typical oils and greases. It has not been shown that ICP's can form stable mixtures with lubricants that are more viscous than conventional solvents at levels that permit the lubricant to retain its lubricity properties, yet have conductivity high enough to protect against static buildup even in applications where the requirements for conductivity through the joint are relatively high.

A further problem faced by lubricants that contain ICP's is that they must withstand relatively high temperatures during operation without substantial loss of the lubricant by evaporation. It is common, for example that bearings can operate at temperatures of up to about 150°C, or 170°C, or even up to about 200°C, and it is necessary that the lubricant have sufficiently low volatility that evaporative losses would be minimal at these temperatures. Although stable solutions of ICP's are know in such solvents as xylene, it is not known that such ICP's will also form suitably stable solutions in less volatile, higher molecular weight lubricants.

Diaz et al. have disclosed conductive lubricants for computer disc drives in U. S. Patent No. 5,641, 841.

The lubricants include either a non-polar oil or a ball bearing grease that is made conductive by the addition of, among other things, conducting polyaniline derivatives made soluble with long chain organic acid or hydrocarbon side chain. Polyaniline salts of dodecylbenzene sulfonic acid (DBSA) and camphor sulfonic acid (CSA) added to the oil at levels up to about 3% by

weight were reported to increase the conductivity of the oil from about 0.1 pmhos/cm (10'13 S/cm) to about 20,000 pmhos/cm (about 2 x 10'8 S/cm). This level of conductivity was said to provide anti-static protection for disc drives. It was not reported whether higher conductivities could be obtained or whether higher levels of the polyaniline salts of DBSA and CSA could be successfully incorporated into the lubricants. However, because all insoluble particles of the ICP salt were removed from the lubricant mixtures by centrifugation, it would be expected that the actual-concentration of the ICP salt in the lubricant mixture would be somewhat lower than 3%, by weight.

A potential problem with the use of the ICP salts of such hygroscopic and deliquescent organic acids as DBSA and CSA, especially at levels above about 3% by weight in paraffinic lubricants, is that their presence at such levels could cause phase separation and/or increased water absorption into the lubricant. This problem is exacerbated because the concentrations of such hygroscopic dopants required to provide the solubility or compatibility needed to maintain the ICP salt in a homogeneous mixture with the lubricant are often quite high. Any increased water absorption would be undesirable because the higher water activity could increase corrosion problems and could result in separation of the lubricant into a paraffinic phase and a second phase that may contain much of the conductive ICP salt. Undesirable phase separation could result in the loss or decrease of electrical conductivity of the lubricant.

Thus, it would be useful to provide a nonvolatile, conductive lubricant that does not contain hard or unplasticized particulate materials which could separate from the lubricant. It would be further desirable if such lubricant could provide corrosion protection for

corrodible metals and was of sufficiently low volatility that evaporative losses would be minimal. If such conductive lubricant contained an ICP, it would be desirable that the composition was sufficiently stable when exposed to moist air at normal ambient conditions that it either did not experience phase separation, or that any separation was easily remedied by gentle mixing.

Moreover, it would be desirable if such ICP-containing conductive lubricant were capable of incorporating over 3% by weight of the ICP salt while remaining in a stable solution.

Summary of the Invention Briefly, therefore, the present invention is directed to a conductive lubricant comprising a stable solution of a nonvolatile, nonconductive lubricant having a dielectric constant no higher than about 3.0 and an intrinsically conductive polymer salt. Also provided is a lubricant comprising a nonvolatile, nonconductive lubricant having a dielectric constant of less than 3.0 and an intrinsically conductive polymer which is non- hygroscopic and is compatible with said nonconductive lubricant. Also provided is a method for producing a conductive lubricant comprising: (a) selecting a nonvolatile, nonconductive lubricant having a dielectric constant of no higher than 3.0, (b) selecting a nonhygroscopic intrinsically conductive polymer salt that forms a stable solution with said nonconductive lubricant, and (c) mixing the nonconductive lubricant with the nonhygroscopic intrinsically conductive polymer salt, thereby to form the conductive lubricant. Also provided is a method for lubricating a joint while providing for electrical conductivity through the joint comprising placing between the moving surfaces of the joint the conductive lubricant that is provided above, thereby lubricating the joint and permitting an

electrical charge to flow from one part of the joint to the other. Also provided is a joint that is lubricated with the conductive lubricant that is described above.

Among the several advantages found to be achieved by the present invention, therefore, may be noted the provision of a nonvolatile, conductive lubricant that does not contain hard or unplasticized particulate materials which could separate from the lubricant, the provision of such a lubricant that provides corrosion protection for corrodible metals, the provision of a conductive lubricant containing an ICP which is sufficiently stable when exposed to normal ambient conditions that it either does not experience phase separation, or that any separation is easily remedied by gentle mixing, and the provision of an ICP-containing conductive lubricant that is capable of incorporating over 3 boy weight of ICP salt while remaining in a stable solution.

Detailed Description of the Preferred Embodiments In accordance with the present invention, it has been discovered that stable solutions of a nonvolatile, nonconductive lubricant having a dielectric constant no higher than about 3.0 and certain intrinsically conductive polymer salts can be formed and that such solutions can serve as conductive lubricants. In particular, certain organic acid salts of intrinsically conductive polymers have been found that can be blended with highly non-polar nonconductive lubricants, such as paraffinic-based oils and greases, to yield lubricants with electrical conductivities of at least 10-8 S/cm.

Significantly -- and surprisingly --, it has been discovered that such ICP salts form stable solutions when blended with the nonconductive lubricant.

It has been found that such stable solutions can be formed when the ICP salts of this invention comprise

ICP salts that are preferably non-hygroscopic and non- deliquescent and are soluble in non-polar solvents such as xylene at levels of about 25% wt/wt. These stable solutions are preferably non-aqueous and can contain at least 3% wt/wt, and even up to 10% wt/wt, or more, of the ICP salt. Moreover, since these solutions are either true solutions, or are stable emulsions or fine dispersions, they do not contain hard or unplasticized particles that can separate from the lubricant. Also, since these conductive lubricants can contain ICP's at levels that are useful for corros-ion protection, the lubricants themselves have been found to provide superior corrosion protection to the metals they contact.

As noted, the conductive lubricant of the present invention comprises a nonconductive lubricant and an ICP salt. The nonconductive lubricants are typically paraffin-based or silicone-based, but the type and grade of lubricant that is used is not critical. Any type of lubricant can be used provided that it has a volumetric electrical conductivity of less than about 10--2 S/cm.

Thus, as used herein, the phrase"nonconductive lubricant"refers to a lubricant of conductivity less than about 10--2 S/cm.

Preferred nonconductive lubricants have lubricity properties and volatility properties that are typical of conventional lubricating oils and greases. In order to minimize the loss of lubricant by evaporation during use, it is preferred that the nonconducting lubricant be a nonvolatile, nonconducting lubricant. As the term "nonvolatile"is used herein, a nonconductive lubricant <BR> <BR> is deemed to be nonvolatile when less than about 0. 5% of the nonconductive lubricant is lost by evaporation in 8 hours while the nonconductive lubricant is being held open to the atmosphere at a temperature of at least about 150°C. Preferably, less than about 0. 5% of the nonconductive lubricant is lost by evporation in 8 hours

while being held at a temperature of at least about 170°C, and most preferably less than about 0. 5 of the nonconductive lubricant is lost by evporation in 8 hours while being held at a temperature of at least about 200°C.

Typical paraffinic lubricants characteristically have dielectric constants (E) of less than about 3.0 at 20°C, and the dielectric constant of many useful paraffinic lubricants is less than 2.0. For example, for <BR> <BR> <BR> n-Hexane, #20°C = 1.89 ; for n-Octane, E2,., 1. 948; for n- Nonane, E20°C = 1.972 ; for n-Decane, e. c = 1. 991, for n- <BR> <BR> <BR> Undecane, #20°C = 2.005; for n-Dodecane, #20°C = 2.014; and<BR> <BR> <BR> <BR> <BR> for parawax and paraffin, #20°C = 2.25 and #20°C = 2.0 - 2.5, respectively. Such low values of dielectric constant indicate that paraffinic lubricants have highly non-polar character. An advantage of lubricants having such non-polar character is that the non-polar lubricants have essentially no compatibility with water (E20-Z = 80. 37), methanol (E20. c = 33. 62), or other low molecular weight, oxygen containing liquid. This incompatibility limits the amount of oxygen that can be absorbed into the lubricant and so protects the metal surface on which the lubricant is used from oxidative corrosion. The preferred nonconductive lubricant of the present invention has a dielectric constant of no higher than about 3.0 at 20°C. It is more preferred that the nonconductive lubricant has a dielectric constant of at most about 2.5, even more preferred of at most 2.25 and especially at most about 2.0 at 20°C.

Representative examples of nonconductive lubricants that are suitable for use in the present invention include non-polar oils and greases, such as ball bearing grease, paraffinic oils and greases and silicone oils and greases. A preferred type of nonconductive lubricant is paraffinic oils and greases.

The nonconductive lubricant of the present invention may contain other materials such as anti- oxidants, stabilizers, and/or any other desirable and useful additive without effecting its utility in the present invention.

The intrinsically conductive polymer ("ICP") salt of the conductive lubricant of this invention may be an acid salt of an intrinsically conductive polymer that is electrically conductive. The terms"intrinsically conductive polymer", and "ICP", as used herein, are intended to include any polymer that, in at least one valence state, has an electrical conductivity greater than about 10-8 S/cm. Preferably the electrical conductivity is greater than about 10-6 S/cm, more preferably greater than about 10-2 S/cm and most preferably greater than about 1.0 S/cm.

ICP's generally have polyconjugated n electron systems and can be doped with an ionic dopant species to an electrically conductive state. A number of conjugated organic polymers that are suitable for this purpose are known in the art and include, for example, substituted and unsubstituted polyaniline, polyacetylene, poly-p- phenylene, poly-m-phenylene, polyphenylene sulfide, polypyrrole, polythiophene, polycarbazole and the like.

It is known that ICP's, and specifically polyaniline, may be made electrically conductive either by electrochemical or chemical polymerization of protonated monomers and by protonation of the neutral polymer by exposure to protonic acids (often called dopants). Polyaniline that is electrically conductive in its doped, or salt, form typically has a conductivity of greater than about 10'8 S/cm. However, in its neutral, or base form, it is non-conductive and has a conductivity of less than about 10-8 S/cm.

In general, polyanilines suitable for use in this invention are homopolymers and copolymers derived from the polymerization of unsubstituted or substituted anilines of Formula I: Formula I

n is an integer from 0 to about 2; m is an integer from 2 to 4, provided that the sum of n and m is equal to 5 ; R1 is aryl, alkyl or alkoxy having from 1 to about 30 carbon atoms, or is a cyano, halo, or acid functional group, such as sulfonic acid, carboxylic acid, phosphonic acid, phosphoric acid, phosphinic acid, boric acid, sulfinic acid and the derivatives thereof, such as salts, esters, and the like ; amino, alkylamino, dialkylamino, arylamino, hydroxy, diarylamino, alkylarylamino, or alkyl, aryl or alkoxy substituted with one or more acid functional groups, such as sulfonic acid, carboxylic acid, phosphonic acid, phosphoric acid, phosphinic acid, boric acid, sulfinic acid and the derivatives thereof, such as salts, esters, and the like; dialkylamino, arylamino, diarylamino, alkylarylamino, hydroxy, alkoxy, alkyl, and R2 is the same as R1, or is different at each occurrence and is selected from the R1 substituents listed above or hydrogen. Particularly preferred for use in this invention is the polyaniline produced from polymerization of unsubstituted aniline.

Polyanilines suitable for use in this invention are generally those which consist of repeat units of the Formulas II and/or III: Formula II

Formula III or consist of a combination of the repeat units of Formulas II and III and having various ratios or the above repeat units in the polyaniline backbone.

Illustrative of preferred polyanilines are those of Formulas IV and V: Formula IV Formula V wherein: n is an integer from 0 to 1;

m is an integer from 3 to 4, provided that the sum of n and m is equal to 4; R1 is alkyl of from 1 to about 20 carbon atoms, carboxylic acid, carboxylate, sulfonic acid, sulfonate, sulfinic acid, sulfinic acid salt, phosphinic acid, phosphinic acid salt, phosphonic acid or phosphonic acid salt; R2 is carboxylic acid, methyl, ethyl, carboxylate, sulfonic acid, sulfonate, sulfinic acid, phosphinic acid, phosphonic acid salt, sulfinate, phosphonic acid, phosphonic acid salt, or hydrogen ; x is an integer equal to or greater than 2; and y is an integer equal to or greater than 1, provided that the ratio of x to y is greater than 1; and z is an integer equal to or greater than about 10.

In the more preferred embodiments of this invention, the polvaniline is derived from aniline or N- alkylaniline either unsubstituted or substituted with at least one sulfonate, sulfonic acid, alkyl or alkoxy. The most preferred polyaniline is polyaniline derived from unsubstituted aniline.

ICP's, and polyaniline in particular, can be prepared by any suitable method. For example, polyaniline may be synthesized by chemical polymerization of ICP-monomers from organic or aqueous solutions or emulsions of mixed aqueous and organic solutions, or by electrochemical polymerization in solutions or emulsions.

Preferred methods for the preparation of polyaniline salts that have high solubilities in organic solvents are disclosed in U. S. Pat. No. 5,567, 356, U. S. Pat.

Application Serial No. 08/596,202 and U. S. Pat.

Application Serial No. 08/868,094, each of which are incorporated by reference herein.

The ICP salt may be formed from any of the above- mentioned ICP's and a protonic acid. It is preferred that the protonic acid be an organic acid. The organic

acid acts as a dopant for the ICP and forms an organic acid salt of the ICP. When added to a polyaniline, for example, the organic acid protonates the polyaniline and forms an electrically conductive organic acid salt of the polyaniline. Such organic acid salts of polyaniline can be formed either during or after polymerization of the aniline monomer into a polyaniline, however, it is preferred that the organic acid salt of polyaniline be formed during the polymerization of aniline.

Organic acids that are preferred as dopants for the ICP's of this invention are those which interact with the ICP to form ICP salts that form stable solutions with the nonconductive lubricant. When it is said that the ICP salt is one that forms a stable solution with the nonconductive lubricant, it is meant that the ICP salt and the nonconductive lubricant can exist in close and permanent association indefinitely in a mixture that may be electrically conductive. More specifically, as used herein, an intrinsically conductive polymer salt is deemed to form a stable solution with a nonconductive lubricant if the ICP salt can be incorporated into the lubricant in an amount of at least about 3% by weight without resulting in phase separation when such ICP salt/lubricant mixture is exposed at normal room temperature to air at a relative humidity of 85 for 12 hours. The term "solution", as used herein, is used in a broad sense and includes emulsions and fine dispersions as well as true solutions. However, the preferred conductive lubricant of the invention is a true solution of the ICP salt and the non-conductive lubricant.

As used herein, when describing a mixture of a lubricant and an ICP salt, the term"phase separation" refers to the separation of a lubricant containing an ICP salt into two separate liquid phases, or a liquid and a solid phase, wherein the ICP salt is preferentially segregated into one of the two phases and the two

separate phases cannot be re-dispersed by agitation with a low-shear mechanical stirring device or by manual stirring. The term"re-dispersed"means that the components of a mixture are distributed to form a solution, an emulsion or a dispersion that does not visibly separate into two or more phases within a period of four hours.

It is further preferred that the organic acid form an ICP salt that is non-hygroscopic and non-deliquescent.

When it is said that the ICP salt is"non-hygroscopic", or that the ICP salt is prepared from an organic acid that is "non-hygroscopic", it is meant that the ICP has been doped with an acid which experiences a weight gain of less than about 5% when exposed to air at 85% relative humidity ("RH") for 12 hours after being conditioned by being held under vacuum at room temperature for 12 hours.

By way of example, an acid sample weighing 100 grams after conditioning as stated above, that weighs 105 grams after exposure for 12 hours to air at room temperature and 85% RH, is said to have experienced a 5% weight gain.

Preferably, the non-hygroscopic acid experiences a weight of less than about 2%, more preferably less than about 1%, and most preferably of less than about 0. 5%.

A material is deemed herein to be"non- deliquescent ", if the material does not melt away or become liquid by attracting and absorbing moisture from the air.

Organic acids which are suitable for use in the present invention, in general, have the formula: FORMULA VI M'- [S03 - R] wherein, M* is a metal or non-metal cation;

R is a substituted or unsubstituted alkyl, phenyl, naphthalene, anthracene or phenanthrene group. The alkyl, phenyl, naphthalene, anthracene or phenanthrene group may have from zero to about four substituents.

Permissible substituents are selected from the group consisting of alkyl, phenyl, haloalkyl and perhaloalkyl groups having from about 6 to about 30 carbon atoms.

Preferred for use in the ICP salts in the present invention are organic acids wherein M is hydrogen and R is alkyl of from about 8 to about 24 carbon atoms or is aryl with at least one alkyl substituent having from about 6 to about 18 carbon atoms, more preferred are organic acids where R is octyl, nonyl, decyl, cetyl, dodecyl, lauryl, palmityl, stearyl, oleyl, linoleyl, or dinonylnaphthalene. The most preferred organic acid for use in ICP salts, and particularly for organic acid salts of polyaniline, is dinonylnaphthalene sulfonic acid.

The preferred ICP salt can be incorporated into a lubricant in an amount of at least about 3% by weight, without phase separation; more preferably in an amount of at least about 4% by weight; even more preferably in an amount of at least about 6% by weight; even more preferably in an amount of at least about 10% by weight, and most preferably in an amount of at least about 15%, by weight, or more. The ability to include ICP's in the conductive lubricant mixture at these concentrations is advantageous, for example, when the ICP desired for use is required to be added at such levels to impart desired levels of electrical conductivity, corrosion resistant, or other useful property to the conductive lubricant.

Phase separation that results in partitioning of the ICP and the non-conductive lubricant is reduced or avoided by selecting a dopant for the ICP which is non- hygroscopic and non-deliquescent, as those terms are defined herein. While the inventors do not wish to be bound by this or any other particular theory, it is

believed that the tendency of an ICP salt to absorb moisture is controlled by the relative hygroscopicity of the counter-ion of the dopant acid. For example, acids such as DBSA, pTSA and camphor sulfonic acid, which are at least hygroscopic, if not deliquescent, readily absorb moisture from moist air, while acids having counter-ions of a more organic and hydrophobic nature, such as dinonylnaphthalenesulfonic acid, for example, either do not absorb moisture, or such absorption is at a much reduced level. It has been found that conductive lubricants that contain ICP salts of dodecylbenzenesulfonic acid (DBSA), in particular, either do not go into solution with paraffinic lubricants, or quickly separate into two phases. This separation is avoided or reduced if the ICP salt of, for example, DNNSA, is used instead.

Separation into two phases can be harmful to a conductive lubricant, especially if the conductive agent accumulates in one phase, leaving the lubricant as a whole non-conductive. If the lubricant is not then mixed upon operation of the device, the device is no longer protected from static buildup and damage.

ICP salts for use in the present invention may be formed by any suitable method and are preferably of the type having a solubility in organic solvents, such as, for example, xylenes, of preferably at least about 10%, more preferably at least about 15%, even more preferably at least about 20%, and most preferably at least 30% or greater on a weight per weight basis. Thus, for a solubility of 25% on a weight per weight basis, 25 grams of such ICP salt will dissolve in 75 grams of xylene at 60°F.

In an embodiment of the present invention where an organic acid salt of polyaniline is used, the xylene- soluble polyaniline salts of dinonylnaphthalene sulfonic acid as prepared by an emulsion-polymerization method as

described in U. S. Patent No. 5,567, 356 are most preferred. Briefly, the method for preparing such preferred xylene-soluble polyaniline salts involves combining water, an organic polymerization solvent in which water is soluble in an amount of at least about 6% wt/wt, an organic acid soluble in said organic solvent, aniline, and a radical initiator such as a chemical oxidant. A particularly preferred organic acid salt of polyaniline, which is made by this method is the polyaniline salt of dinonylnaphthalene sulfonic acid (PANI-DNNSA). Polyaniline salt produced by this emulsion-polymerization method is readily processible as a result of its being highly soluble in a variety of organic solvents. For example, one such organic solvent is xylene which dissolves the DNNSA salt of polyaniline as prepared by emulsion polymerization at a concentration equal to or greater than about 25% by weight.

The amount of dopant that is added to the ICP to form the ICP salt is believed to have an effect on the relative solubility of the ICP salt in organic solvents and also to have an effect on the electrical conductivity of the ICP salt. In general, it is true that the higher the dopant concentration in the ICP salt, the higher the electrical conductivity. However, the effect of the doping level on the solubility of the ICP salt in non- polar organic solvents depends upon the chemical character of the dopant. Higher levels of dopants such as hydrogen chloride or sulfuric acid, for example, reduce the solubility of the ICP salt in organic solvents, while increased levels of dopants such as, for example, paratoluenesulfonic acid, dodecylbenzenesulfonic acid and, in particular, dinonylnaphthalenesulfonic acid, normally increase the organic solubility.

The amount of dopant that is added to an ICP is commonly expressed in terms of the moles of dopant acid per mole of ICP monomer unit. In the case of an acid

salt of polyaniline, the relative amount of dopant would be expressed as moles acid per aniline monomer unit. By way of example, an ICP salt comprising 100 moles of a protonic acid that are associated with a polymer chain of an ICP that is composed of 100 ICP monomer units, has a dopant: ICP monomer unit ratio of 1: 1. The dopant: ICP monomer unit ratios for ICP salts that are useful in the present invention preferably range from about 0.5 : 1 to <BR> <BR> about 3: 1, or higher, more preferably from about 0. 8 : 1 to<BR> <BR> 1. 9 : 1, and most preferably from about 1 : 1 to about 1.6 : 1.

In another embodiment of-the present invention, the ICP salt can be replace in the subject lubricant with an undoped, neutral ICP. Such undoped or neutral ICP's typically have low conductivities, but are useful in that in certain cases they provide corrosion protection to metals with which they come in contact and can exhibit higher thermal stability than doped ICP's.

Thus, for applications where it is not particularly desirable to provide electrical conductivity by addition of a conductive ICP salt, yet it is desirable to provide the corrosion protection of an ICP, the use of such neutral, undoped ICP's is advantageous.

Either doped or undoped ICP can be used in the present lubricant in conjunction with any other antistatic additive, or mixture of additives. Examples of other such antistatic additives include STADIS-450¢ (a trademark of DuPont), ASA-3* (a trademark of Shell), N- tallow-1,3-diaminopropane and epichlorohydrin in aromatic solvents, 1-decene polysulfone, dicocodimethylammonium nitrate, alkylsalicylates, sulfonates, succinimides, magnesium oleate, calcium salt of nitrate lube oil with 10% stearic acid, chromium salts of C - C20 synthetic fatty acids in toluene, chromium stearate, chromium oleate, chromium linoleate, cobalt naphthenate, copper naphthenate, nickel naphthenate, diethylamine, 2- methylpyridine, 3-methyl pyridine, 2-amino-5-

nitropyridine, 2, 6-dinitro-3-chloropyridine, metal caged fullerenes and stearylanthranilic acid.

The subject lubricant can be prepared by mixing the non-conductive lubricant with the ICP, or ICP salt.

The method of mixing is not particularly important, but it should result in a solution, emulsion, or fine dispersion of the ICP, or ICP salt in the lubricant.

When an ICP salt is used, the solution, emulsion, or fine dispersion will have a conductivity of at least about 10-8 S/cm.

A preferred method of mixing the ICP salt with the non-conductive lubricant is to add a solution of the ICP salt in a volatile non-polar organic liquid, such as, for example, xylene, to the non-conductive lubricant and subject the mixture to very high-shear blending until the mixture appears to be homogeneous. Such high shear blending can be carried out with a device such as a bio- homogenizer (such as a Biospec Model M133/1281-0), for example. The mixture is then heated to remove the volatile non-polar organic liquid by evaporation. After the non-polar organic liquid is removed, the mixture is again subjected to high-shear blending, such as with the bio-homogenizer until the mixture appears to be homogeneous. If some settling, or separation occurs in the conductive lubricant upon storage or standing, the materials can be easily redistributed by mixing with a low-shear device or by manual stirring.

As an alternative, the subject lubricant can be formed by removing the volatile solvent, if any, from the ICP salt by evaporation and then mixing the ICP salt with the non-conductive lubricant in a mortar and pestal for 1 or 2 hours. The mixing can also be carried out in any mixer suitable for mixing pastes or viscous liquids and solids at medium to high shear. It is preferable that such mixture be subjected to a high shear mixing, such as by a Biohomogenizer, after the first mixing step. After

the ICP salt forms a solution with the non-conductive lubricant, the composition is ready for use.

The conductive lubricant of the present invention can be liquid or semi-solid in form and, in fact, can have any physical form suitable for use in a manner as such lubricants are conventionally used. The volumetric electrical conductivity of the conductive lubricant is at least about 10-8 S/cm, and is preferably about 10-6 S/cm, more preferably about 10'4 S/cm and most preferably about 10-2 S/cm, or higher.

While the subject lubricant may be in the form of a dispersion of fine particles, it is free of particles of hard or unplasticized materials such as metals or carbon that can separate from the lubricant and damage sensitive components of fine electrical instruments, computers and the like. The presence of the ICP salt in the lubricant preferably does not significantly change the lubricity of the subject lubricant from that of the nonconductive lubricant that is selected for use as the base lubricant. However, the presence of the ICP provides the avantage that any corrodible metals that are contacte by the subject lubricant are additionally protected against corrosion and pitting. This property of ICP's is well known in the art and is described in U. S. Patents No. 5,532, 025,5, 648,416, 5,441, 772, 5,658, 649 and 5,645, 890, among others. The presence of the ICP in contact with a corrodible metal surface is believed to passivate the metal surface and, by transferring charges from the metal to its surroundings, maintain the metal surface in such a passive state, thus inhibiting or preventing corrosion. This property of the ICP-containing subject lubricant is especially advantageous in fine electrical machinery and ball bearings where the uncontrolled discharge of static electricity coupled with some degree of oxidative

corrosion can combine to cause significant wear of the device leading to eventual malfunctioning.

In addition to various other conductive additives in addition to the ICP salt, which may be added to the subject lubricant, other desirable additives may also be used. Such additives may include Anti-oxidants, anti- static agents, plasticizers, surfactants, pigments and the like. In a preferred embodiment, diphenyl sulfone has been found to be an especially advantageous additive.

The subject lubricant can be used in any application where a corrosion resistant lubricant that may or may not be electrically conductive would be useful. If the lubricant is conductive, it would be especially useful in applications such as the lubrication of joints in fine electro-mechanical instruments and machinery. Such applications abound in the fields of computers, instrumentation and controls, laboratory analytical devices and other similar areas. Furthermore, depending upon the qualities of the non-conductive lubricant, it may be possible to use the conducting lubricant in medical and physiological applications where some electrical conductivity is important.

The following examples describe preferred embodiments of the inventions. Other embodiments within the scope of the claims herein will be apparent to one skilled in the art from consideration of the specification or practice of the invention as disclosed herein. It is intended that the specification, together with the examples, be considered exemplary only, with the scope and spirit of the invention being indicated by the claims which follow the examples.

EXAMPLE 1 Demonstrating incorporation of an ICP salt with a paraffinic oil.

A sample of a polyaniline salt of dinonylnaphthalene sulfonic acid (PANI-DNNSA in solution in xylene; batch number 5883327) was mixed with 3-in-1 Oil (available from Boyle-Midway, Inc., NY, NY) with stirring at room temperature. A mixture containing 20% by weight of the PANI-DNNSA gave a dark green liquid mixture with no visible solids or particulates. The liquid appeared to be a solution.

EXAMPLE 2 Demonstrating formulation--of the dinonylnaphthalene sulfonic acid salt of polyaniline with a commercial paraffinic lubricant.

A sample of the dinonylnaphthalene sulfonic acid salt of polyaniline (2.5 g of XICP-OSO1, 40% solids in xylene, lot number 6076624, available from Monsanto Company, St. Louis, Missouri) was added to Nye hydrocarbon lubricant (9 g, available from Nye Lubricants Inc., New Bedford, MA) at very high shear using a bio- homogenizer (Biospec model M133/1281-0). A homogeneous solution was obtained. The solution was heated on a hot plate with constant stirring at about 90°C to evaporate xylene. After all xylene was removed, the solution was cooled to room temperature and once again subjected to high shear with the homogenizer. A dark green dispersion of polyaniline salt in the lubricant was obtained. Some settling occurred with time on standing, revealing a clear green supernatant, however the sediment could easily be re-dispersed with mild stirring.

EXAMPLE 3 Demonstrating formulation of the dinonylnaphthalene sulfonic acid salt of polyaniline with a commercial paraffinic lubricant having a conductivity suitable for static discharge.

Nacure 1052 (2 g; Nacure 1052 is a mixture of approximately 50% wt/wt dinonylnaphthalene sulfonic acid in n-heptane, available from King Industries, Inc., was mixed with a dinonylnaphthalene sulfonic acid salt of polyaniline (2.5 g, XICP-OSO1, 40% solids in xylene, lot number 6076624, available from Monsanto Company) and added to Nye hydrocarbon lubricant (9 g) at very high shear using a bio-homogenizer as in Example 2. The solution was heated on a hot plate with constant stirring at approximately 90°C to remove xylene and n-heptane.

After xylene and heptane were removed, the solution was cooled to room temperature and again subjected to high shear mixing with the homogenizer. The mixture contained 10% wt/wt of PANI-DNNSA solids. This dispersion showed better stability (less settling in the same period of time) than the dispersion of Example 2. Again, however, re-dispersion of sediment was easily accomplished by mild stirring. The volumetric conductivity of the material was found to be 10'8 S/cm. The conductivity was calculated from measurements of the resistance as a function of immersion depth as two 1. 25" x 3"copper plates spaced 0. 1" apart were lowered into the subject lubricant.

EXAMPLE 4 Demonstrates the formulation of the dinonylnaphthalene sulfonic acid salt of polyaniline with a commercial paraffinic lubricant and sodium dioctyl sulfosuccinate to obtain improved stability.

A mixture of Nye lubricant and PANI-DNNSA was prepared as in Example 2, except that sodium dioctyl sulfosuccinate (1.0 g, available from Aldrich Chemicals) was added to the Nye lubricant before the PANI-DNNSA was added. Otherwise, mixing and solvent removal were the same as in Example 2. As before, a dark green dispersion of polyaniline salt in the lubricant was obtained,

however the presence of the sodium dioctyl sulfosuccinate resulted in much better stability for the dispersion relative to the dispersions of Examples 2 and 3.

REFERENCE EXAMPLE 1 This illustrates the relative hygroscopicity of dodecylbenzenesulfonic acid and dinonylnaphthalenesulfonic acid.

A sample of each of dodecylbenzenesulfonic acid (DBSA) and dinonylnaphthalenesulfonic acid (DNNSA, available from King Industries,'Inc.) were placed in a vacuum oven at room temperature and subjected to vacuum for 12 hours. After removal from the vacuum oven, a measured weight of each of the samples were placed in a relative humidity chamber at room temperature in air controlled at a relative humidity of 85%. After 12 hours under these conditions, the samples were weighed to determine the amount of moisture uptake from the humid air. It was found that the sample of DBSA had increased in weight by 10% during the test period and the sample of DNNSA had increased in weight by less than 0. 5%. This indicates that the DBSA is a hygroscopic organic acid while the DNNSA is a non-hygroscopic organic acid.

EXAMPLE 5 This illustrates the formation of a stable solution of paraffinic lubricant with polyaniline doped with DNNSA contrasted with the lack of formation of a stable solution of the same paraffinic lubricant with polyaniline doped with DBSA.

The polyaniline salt of DBSA was prepared according to the method disclosed in U. S. Patent No.

5,641, 841, to Diaz et al. Polyaniline base was added to DBSA in a mortar and pestal and ground for one hour to yield a dry paste. The ratio of DBSA-to-aniline monomer unit in the polyaniline (DBSA: aniline monomer unit) was

0.5 : 1. A paraffinic oil-based lubricant (type MM971015, lot# MM971027, available from Nye Lubricants, Inc.) was slowly added to the paste in the mortar and pestal with grinding to yield a 10% by weight emeraldine salt dispersion in the lubricant. The dispersion was sonicated using ultrasound for 5 hours and then left overnight under vacuum (25 inches Hg) at room temperature. At the end of this time, it was noticed that the major part of the emeraldine salt settled out of the lubricant and appeared as a sludge on the bottom of the vessel. The supernatant liquid had an extremely faint green color and also appeared hazy. In order to determine the cause of the haze, an equivalent amount of DBSA was added to fresh lubricant. This caused an immediate haziness to form in the lubricant. It was concluded that very little -- less than 0. 5% by weight -- of the polyaniline DBSA went into solution in the lubricant.

To test the effect of the DBSA: aniline monomer unit ratio on the solubility of the emeraldine salt in the Nye lubricant, the procedure disclosed above was repeated, except with a DBSA: aniline monomer unit ratio of 2: 1 rather than 0.5 : 1. Once again, however, the major part of the emeraldine base settled out at the bottom as a sludge and the supernatant liquid had an extremely faint green color and appeared hazy. From the observed optical density of the green color in the lubricant, it appeared that the addition of the excess DBSA did not appear to increase the amount of polyaniline salt dispersed in the lubricant.

In a third trial, organic soluble polyaniline salt of DNNSA (XICP-OSO1, available from Monsanto Company) was vacuum dried at 60°C to remove all xylene. The resulting sludge was added to a mortar and pestal and a blend containing 10% by weight of the polyaniline salt in Nye lubricant was produced as described above. The

dispersion obtained was extremely homogeneous and appeared to be a solution with very high optical density (signifying that a true solution, an emulsion or a fine dispersion had been formed with the polyaniline salt and the Nye lubricant). This dispersion was sonicated using ultrasound for one hour and left overnight under vacuum (25 inches Hg) at room temperature. After this time, no settling was observed in the solution and the dispersion appeared to be very stable. In fact, no settling was observed in the solution after standing for three days at room temperature. No haziness was observed in the solution when viewed in thin sections (due to high optical density). It was concluded that the polyaniline- DNNSA salt formed a stable solution with the Nye lubricant while the polyaniline-DBSA salt did not.

In view of the above, it will be seen that the several advantages of the invention are achieved and other advantageous results obtained.

As various changes could be made in the above methods and compositions without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.