CA2134798A1

CA2134798A1 - Open gear lubricant composition

Info

Publication number: CA2134798A1
Application number: CA 2134798
Authority: CA
Inventors: David Anthony Slack; Carol A. Barnes
Original assignee: Individual
Current assignee: Imperial Oil Ltd
Priority date: 1993-11-02
Filing date: 1994-11-01
Publication date: 1995-05-03

Abstract

ABSTRACT OF THE DISCLOSURE

This invention is an open gear lubricating composition formulated by thickening a fluid containing a base oil, a synthetic fluid and preferably also a high molecular weight polymer, while other materials such as extreme pressure, anti-wear, anti-corrosion, anti-oxidant and solid lubricant additives may also be employed if desired.
This lubricant provides adequate gear protection and dispersing performance in machinery employing large, slow moving gears under heavy loads.

Description

213~798 ~ 1 -Field of the Invent~on This invention relates to an open gear lubricating composi-tion suitable for use in machinery employing large, slow-moving gear under heavy loads.

~escription of the Related Art -,' Open gear lubricating oils and greases are employed under conditions wherein a key aspect of their performance is their dispensibility in automatic spray or drip systems. Currently product dispensibility is achieved by use of dispensing solvents such as 1,1,1-trichloroethane. This solvent and others like it have been identified as ozone depleters and their future use is being severely limited or totally banned under international agreement. Other dispensing solvents which are not as environmentally objectionable are hydrocarbon diluents. However, the high rates of evaporation of hydrocarbon solvents suitable for use as dispensing solvents creates a safety problem due to the low flash point of this type of solvent.

Various solutions have been offered in the industry.

U.S. Patent 5,190,682 discloses a lubricant mixture suitable for use as a base fluid in open gear greases comprising 10 to 90 wt%
of a liquid polybutene having a viscosity at 38C in the range of 1,000 to 20,000 mm2/s and a viscosity at 100C in the range of 40 to 500 mm2/s and 10 to 90 wt% of a liquid polyalphaolefin having a viscosity at 38C in the range 10 to 75 mm2/s and a viscosity at 100-C
in the range of 2 to 15 mm2/s. This base fluid is combined with a thickener and at least one additional component selected from solid lubricants, extreme pressure additives, stabilizers, anti-oxidants, and anti-corrosion additives.

Canadian Patent 1,311,463 discloses a lubricating composi-tion containing a base oil containing 5 to 100 wtX of a mineral oil :i,,~. ;-,`: . -2I3~798 having a kinematic viscosity at 40'C of 2 to 2000 cSt, a viscosityindex of 70 or higher, 0-95 wt% of a polybutene having a molecular weight of 200 to 1000 and at least one additive selected from extreme pressure agents, an anti-wear agent and an oiliness agent.

Canadian Patent 1,277,309 discloses a lubricating composi-tion containing a base oil containing 15-85 parts of a mineral oil having a viscosity at 100-C in the range 2-50 cSt which mineral oil contains less than 20 wt% aromatic hydrocarbons and 50 ppm by weight or less sulfur, and 15-85 parts of a polyalphaolefin having a viscosity at 100C of 1.5 to 150 cSt.

Canadian Patent 2,101,924 discloses a lubricating composi-tion containing a base oil containing a naphthenic, paraffinic, aromatic or synthetic oil component, a thickener, an extreme pressure wear-resistant additive and a water-resistant hydrophobic polymeric additive such as polyolefin, polyisobutylene or styrene-isoprene.

Canadian Patent 1,288,409 discloses a grease composition containing naphthenic oil and/or polybutene oil (77-95 wt%) and an additional polymeric material of styrene-rubber-styrene or styrene-rubber block copolymers and colloidal particles of fumed silica, precipitated silica or clay.

USP 5,116,522 discloses a grease composition comprising a lubricating oil, a thickener, a Viscosity Index improver and certain ethylene copolymers having a Melt Index of at least about 40 9/10 minutes. This grease is reported as having excellent high temperature adhesiveness and low temperature slumpability.

It would be desirable to have an open gear lubricant exhib-iting good viscosity, adhesion and dispersion performance, suitable for use in machinery employing large, slow moving gears under heavy load but which does not employ dispersing solvents such as trichloro-ethane or hydrocarbon diluents.

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213~798 Summarv of the Invention This lnvention relates to an open gear lubricant having good viscosity, adhesion and dispensing performance and useful in machinery employing large, slow moving gear under heavy loads comprising (A) a base oil component having a viscosity of less than 220 cSt e40-c, (B) one or more synthetic fluid component(s) each having a viscosity of about 2 to 2,000 cSt @100C, wherein A and B are combined in a ratio so as to produce a base oil blend having a viscosity of between about 20 and about 900 cSt @40C, (C) from 0 to 5 wt% of a high molecular weight polymer; such that the lubricating fluid component viscosity of the resulting lubricant is at least 320 cSt @40-C; (D) from 1.0 to 20 wt% of a thickener, and optionally (E), from 1 to 15 wt% solid lubri-cant and (F) from 0 to 10 wt% of other materials selected from the group consisting of extreme pressure additives, anti-wear additives, anti-corrosion additives, anti-oxidant additives, pour point depres-sants, tackiness agents, dyes and mixtures thereof.

Detailed Description of the Invention In the present invention the open gear lubricating composi-tion comprises a mineral oil component, a synthetic oil component, a high molecular weight polymer component, a thickener component and, optionally other additives typically utilized in formulating open gear lubricants.

The base oil component of the present composition is any natural or synthetic oil boiling in the lubricating oil boiling range, e.g., about 200 to 800-C and possessing a viscosity of less than 220 cSt @40-C, preferably less than 100 cSt @40-C, most preferably about 10 cSt @40-C, and simultaneously a viscosity of less than 18 cSt @100-C, preferably less than 10 cSt @100-C, most preferably about 2 to 3 cSt @100-C.

The base oil can be any of the conventionally used mineral oils, synthetic hydrocarbon oils or synthetic ester oils. Mineral ~ .
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213~798 lubricating base oils used in preparing the greases can be any conven-tionally refined base stocks derived from paraffinic, naphthenic and mixed base crudes. Synthetic lubricating base oils that can be used include esters of glycols such as C13 oxo acid diester of tetraethylene glycol, or complex esters such as one formed from 1 mole or sebacic acid and 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid. Other synthetic oils that can be used include synthetic hydrocarbons such as polyalphaolefins; alkyl benzenes, e.g.
alkylate bottoms from the alkylation of benzene with tetrapropylene, or the copolymers of ethylene and propylene; polyglycol oils, e.g.
those obtained by condensing butyl alcohol with propylene oxide;
carbonate esters, e.g. the product of reacting C8 oxo alcohol with ethyl carbonate to form a half ester followed by reaction of the latter with tetraethylene glycol, etc. Other suitable synthetic oils ;nclude the polyphenyl esters, e.g. those having from about 3 to 7 ether linkages and about 4 to 8 phenyl groups. Mineral oils derived from naphthenic crude sources are particularly preferred.

The composition will also employ one or more synthetic fluid component(s) characterized as possessing a viscosity ranging from about 2 to 2,000 cSt @100-C, preferably about 30 to about 1,500 cSt @
100-C, most preferably about 100 to about 1,000 cSt @100-C. The synthetic fluid component can be synthetic organic materials such as polyesters, polyalphaolefins, polybutenes, polyalphaolefin/polymeth-acrylate block co-polymers, polyalphaolefin/poly (alkyl) methacrylate block copolymers, high Viscosity Index (VI) isoparaffins produced by hydrocracking or hydroisomerization of waxes or waxy oils e.g. waxy distillates or raffinates (see eg USP 4,937,399, USP 4,929,795, USP
4,923,588, USP 4,992,159, USP 5,059,299), and mixtures thereof.
Polybutenes are materials well known in the art. Polyalphaolefins are also well known in the art and can be prepared, for example, by polymerization of ethylene in a plurality of stages to produce a product predominating on alpha olefins, as described in U.S. Patent 3,482,000. Poly alkyl methacrylate and polymethacrylate are also well known in the art.

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. -213~798 In producing the open gear lubricant the base oil having aviscosity in its previously recited range and the synthetic fluid component(s) having a viscosity in its previously recited range are combined in any ratio of base oil (A) to synthetic fluid(s) (B) such that the viscos;ty of the resultant combination ;s between about 20 and about 900 cSt @40-C, preferably between about 50 and about 700 cSt @40-C, most preferably between about 100 and about 200 cSt @40-C. In the final composition the lubricating flu;d component of the compos;-tion, less thickeners, solid lubricant(s), or other additives exhibits a viscosity of at least 320 cSt @40-C, preferably at least 460 cSt @40-C, more preferably at least 680 cSt @40-C.

A base oil soluble high molecular weight polymer is preferably also used in addition to the two previously recited components. The polymer typically have a number average molecular weight of greater than about 25,000, preferably greater than about 50,000, most preferably greater than about 100,000.

Examples of base oil soluble high molecular weight polymers include styrene-isoprene block copolymers, radial divinylbenzene-isoprene copolymers, olefin copolymers, polymethacrylates, polyalkyl methacrylates. The high molecular weight polymer can be used either as individual polymers or as mixtures of different polymers.

The base oil soluble high molecular weight polymer is used in combination with the base oil/synthetic liquid blend in an amount sufficient to insure that the viscosity of the lubricating fluid components of the resulting lubricant, less thickeners, solid lubri-cants and other add;tives to at least 320 cSt @40-C, preferably at least 460 cSt ~40-C, most preferably at least 680 cSt @40'C.
Typically about 0 to 5 wtX and preferably about 0.5 to 5 wt%, more preferably about 1 to about 3 wt~, of high molecular weight polymer, based on the base oil/synthetic fluid blend, will be employed. To achieve a lubricating fluid component viscosity in the final composi-tion of above about 900 cSt e40- it is necessary to employ the high molecular weight copolymer so as to insure that the resulting grease . - .:
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213~798 is pumpable. Preferably, however, the lubricating composition will contain high molecular weight polymers.

In the styrene/isoprene block copolymer of the structure A-B, the polymer A block is a polymerized styrene having an average molecular weight between about 10,000 and about 55,000, preferably about 25,000 and about 50,000. Polylsoprene is the conjugated diene employed in preparing the precursor block B. Preferably the polyisoprene block should have at least about 80%, preferably 88%, 1,4-structure which may be cis or trans and an average molecular weight between about 35,000 and 80,000. The weight ratio of block A
to block B is between about 0.45:1 and 0.8:1, preferably 0.5:1 to 0.7:1. The average molecular weight of the styrene/isoprene block copolymers is between about 80,000 to about 120,000.

The block copolymers are commercially available from Shell Chemical Company as Shellvis 40 and Shellvis~ 50. Such copolymers are prepared according to the methods described in U.S. Patent 3,772,196, which is incorporated herein by reference. The block copolymers are prepared using lithium-based initiators, preferably lithium alkyls such as lithium butyls or lithium amyls. Polymeriza-tion is usually conducted in solution in an inert solvent such as cyclohexane or alkanes such as butanes or pentanes and mixtures of the same. The first monomer to be polymerized (which may be either styrene or isoprene) is injected into the system and contacted with the polymerization initiator which is added in an amount calculated to provide the predetermined average molecular weight. Subsequent to obtaining the desired molecular weight and depletion of the monomer, the second monomer is then injected into the living polymer system and block polymerization occurs, resulting in the formulation of the living block copolymer poly(styrene)-polyisoprene which is then killed, e.g., by the addition of methanol.

This precursor is then subjected to selective hydrogenation to form the block copolymers. Preferably hydrogenation is conducted in the same solvent in which the polymer was prepared, utilizing a catalyst comprising the reaction product of aluminum alkyl and a .,,~ ,.. ..

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213~798 nickel or cobalt carboxylate or alkoxide. A favored catalyst is the reaction product formed from triethyl aluminum and nickel octoate.

The temperatures and pressures employed in the hydrogenation step are adjusted such as to cause essentially complete hydrogenation of the polyisoprene block with essentially no effective hydrogenation of the monoalkenyl arene polymer block.

The polymer may be isolated from its solvent after its hydrogenation and dispersed in lubricating oil. This may be effected, for example, by adding a lubricating oil to the solution of hydroge-nated polymer and thereafter evaporating the relatively volatile solvent.

The radial divinylbenzene-isoprene polymer has a poly-(divinylbenzene coupling agent) nucleus and hydrogenated polyisoprene arms linked to the nucleus. The average molecular weights of each arm are from about 15,000 to about 100,000, and the average molecular weight of the star polymer is between about 250,000 and 1,250,000, preferably 350,000 to 1,000,000.

These polymers are commercially available from Shell -~
Chemical Company as Shellvis0 200 and Shellvis~ 250. These polymers ~ ~
are prepared using the methods described in U.S. Patent 4,116,917, ~:
which is incorporated herein by reference, and are generally produced by the process comprising the following reaction steps: `

(a) polymerizing isoprene in the presence of an ionic initiator to form a living polymer, (b) reacting the living polymer with a poly(divinylbenzene coupling agent) tc form a star-shaped polymer, and (c) hydrogenating the star-shaped polymer to form a hydrogenated star-shaped polymer.

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213~798 The living polymers produced from isoprene in reaction step (a) are the precursors of the hydrogenated polymer chains which extend outwardly from the poly(divinylbenzene coupling agent) nucleus.

As is well known, living polymers may be prepared by anionic solution polymerization of conjugated dienes and, optionally, monoalkenyl arene compounds in the presence of an alkali metal or an alkali-metal hydr~carbon, e.g. sodium naphthalene, as anionic initiator. The preferred initiator is lithium or a monolithium hydrocarbon. Suitable lithium hydrocarbons include unsaturated compounds such as allyl lithium, methallyl lithium; aromatic compounds such as phenyllithium, the tolyllithiums, the xylyllithiums and the naphthyllithiums and in particular the alkyl lithiums such as methyl-lithium, ethyllithium propyllithium, butyllithium, amyllithium, hexyllithium, 2-ethylhexyllith;um and n-hexadecyllithium. Secondary-butyllithium is the preferred initiator. The initiators may be added to the polymerization mixture in two or more stages optionally together with additional monomer. The living polymers are olefinically unsaturated. The concentration of the initiator used to prepare the living polymer may also vary between wide limits and is determined by the desired molecular weight of the living polymer.

The solvents in which the living polymers are formed are inert liquid solvents such as hydrocarbons e.g. aliphatic hydrocar-bons, such as pentane, hexane, heptane, octane, 2-ethylhexane, nonane, decane, cyclohexane, methylcyclohexane or aromatic hydrocarbons, e.g.
benzene, toluene, ethylbenzene, the xylenes, diethylbenzenes, propyl-benzenes. Cyclohexane is preferred. Mixtures of hydrocarbons e.g.
lubricating oils may also be used.

The temperature at which the polymerization is carried out may vary between wide limits such as from -50-C to 150-C, preferably from about 200- to about 800-C. The reaction is suitably carried out in an inert atmosphere such as nitrogen and may be carried out under pressure e.g. a pressure of from about 0.5 to about 10 bars.

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~t,.:,: ,. : , 213~798 g The living polymers produced ~n reaction step (a) are then reacted, in reaction step (b), wlth a polydivinylbenzene coupling agent. Polyalkenyl coupling agents, such as polydivinyl benzene, capable of forming star-shaped polymers are known. See generally, Fetters et al., U.S. Patent No. 3,985,830. They are usually compounds having at least two non-con~ugated alkenyl groups. Such groups are usually attached to the same or different electron-withdrawing groups e.g. an aromatic nucleus. Such compounds have the property that at least two of the alkenyl groups are capable of independent reaction with different living polymers and in this respect are different from conventional conjugated diene polymerizable monomers such as butadiene, isoprene, etc.

The polyvinylbenzene coupling agent should be added to the living polymer after the polymerization of isoprene is substantially complete, i.e. the agent should only be added after substantially all of the isoprene monomer has been converted to living polymers.

The amount of polydivinylbenzene coupling agent added may vary between wide limits, but preferably at least 0.5 mole is used per mole of unsaturated living polymer. Amounts of from 1 to 15 moles, preferably from 1.5 to 5 moles are preferred. The amount, which may be added in two or more stages, is usually such so as to convert at least 80 or 85% of the living polymers into star-shaped polymers.

The reaction steps (b) may be carried out in the same solvent as for reaction step (a). A list of suitable solvents is given above. The reaction step (b) temperature may also vary between wide limits e.g. from 0- to 150-C, preferably from 20-C to 120'C. The reaction may also take place in an inert atmosphere e.g. nitrogen and under pressure e.g. a pressure of from 0.5 to 10 bars.

The star-shaped polymers prepared in reaction step (b) are characterized by having a dense center or nucleus of cross-linked poly(polydivinylbenzene coupling agent) and a number of arms of substantially linear polyisoprene extending outwardly therefrom. The ~ ~ '' ' .: .~ - - .
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~''.. '''~''' - : - ` ' ` ` 213 1798 number of arms may vary considerably, but is typically between 4 and 25, preferably from about 7 to about 15.

Such star-shaped polymers, which are still "living", may then be deactivated or "killed", in known manner, by the addition of a compound which reacts with the carbanionic end group. As examples of suitable deactivators may be mentioned, compounds with one or more active hydrogen atoms such as water, alcohols (e.g. methanol, ethanol, isopropanol, 2-ethylhexanol) or carboxylic acids (e.g. acetic acid), compounds with one active halogen atom, e.g. a chlorine atom (e.g.
benzyl chloride, chloromethane), compounds with one ester group and carbon dioxide. If not deactivated in this way, the living star-shaped polymers will be killed by the hydrogenation step (c).

In step (c), the star-shaped polymers are hydrogenated by any suitable technique. Suitably at least 50%, preferably at least 70%, more preferably at least 90%, most preferably at least 95% of the original olefinic unsaturation is hydrogenated. Preferably less than 10X, more preferably less than 5% of such aromatic unsaturation is hydrogenated. The hydrogenation can be carried out in any desire way.
A hydrogenation catalyst may be used e.g. a copper or molybdenum compound. Compounds containing noble metals or noble-metal compounds can be used as hydrogenation catalysts. Preference is given to catalyst containing a non-noble metal or a compound thereof of Group VIII of the Periodic Table, i.e. iron, cobalt and in particular, nickel. As examples may be mentioned, Raney nickel and nickel on kieselguhr. Special preference is given to hydrogenation catalysts which are obtained by causing metal hydrocarbyl compounds to react with organic compounds of any one of the group VIII metals iron, cobalt or nickel, the latter compounds containing at least one organic compound which is attached to the metal atom by means of an oxygen atom. Preference is given to hydrogenation catalysts obtained by causing an aluminum trialkyl (e.g. aluminum triethyl (Al(Et)3) or aluminum triisobutyl) to react with a nickel salt of an organic acid (e.g. nickel diisopropyl salicylate, nickel naphthenate, nickel 2-ethyl hexanoate, nickel di-tert-butyl benzoate, nickel salts of saturated monocarboxylic acids obtained by reaction of olefins having .. ,.~ . . . .
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213~798 from 4 to 20 carbon atoms in the molecule with carbon monoxide and water in the presence of acid catalysts) or with nickel enolates or phenolates (e.g. nickel acetonylacetonate, the nickel salt of butyl-acetophenone).

The hydrogenation of the star-shaped polymer is very suit-able conducted in solution in a solvent which is inert during the hydrogenation reaction. Saturated hydrocarbons and mixtures of saturated hydrocarbons are very suitable and it is of advantage to carry out the hydrogenation in the same solvent in which the polymer-ization has been effected.

The hydrogenation star-shaped polymer is then recovered in solid form from the solvent in which it is hydrogenated by a conve-nient technique such as by evaporation of the solvent.

The open gear lubricating composition will also contain a thickener dispersed in the lubricating oil to form a base grease.
However, the particular thickener employed is not critical and can vary broadly provided it is essentially water insoluble. For example, the thickener may be based on aluminum, barium, calcium, lithium soaps, or their complexes. Soap thickeners may be derived from a wide range of animal oils, vegetable oils, and greases as well as the fatty acids derived therefrom. These materials are well known in the art and are described in, for example, C. J. Boner, Manufacture and Application of Lubricating Greases, Chapter 4, Robert E. Krieger Publishing Company, Inc., New York (1971). Carbon black, silica, and clays may be used as well as dyes, polyureas, and other organic thickeners. Pyrrolidone based thickeners can also be used. Preferred thickeners are based on lithium soap, calcium soap, their complexes, or mixtures thereof. Particularly preferred is a lithium or lithium complex thickener that incorporates an hydroxy fatty acid having from 12 to 24 (preferably from 16 to 20) carbon atoms. A preferred hydroxy fatty acid is an hydroxy stearic acid (e.g., a 9-hydroxy or a 10-hydroxy stearic acid) of which 12-hydroxy stearic acid is most preferred (See U.S. Pat. No. 3,929,651, the disclosure of which is incorporated herein by reference). The amount of thickener in the ;.

~ ,-,~. .: ; .. . ` --. ~
,.", .. . ~-~'i,' ,' 213~798 lubricating compositlon will typically range from about 1 to about 20 wt%. For most purposes, between about 1 to about 10 wt%, preferably between about 1 to about 5 wtX, of the thickener will be present in the composition. The grease preferably has a hardness between an NLGI
rating of 000 to 2, preferably between 0 and 00 as measured by ASTM
D217.

The open gear lubricating composition may also contain small amounts of supplemental additives which include, but are not limited to, anti-corrosive agents, extreme pressure agents, antiwear agents, pour point depressants, tackiness agents, oxidation inhibitors, dyes, and the like, which are incorporated for specific purposes. The total amount of these additives will typically range from 0 to about 10 wt%
based on total weight of the grease composition. In addition, solid lubricants such as molybdenum disulfide and graphite may also be present in the composition -- typically from about 1 to 15 wt% of a solid lubricant, e.g., 1 to about 5 wt%, preferably from about 1.5 to about 3 wt% for molybdenum disulfide and from about 3 to about 15 wt%, preferably from about 3 to about 12 wt% for graphite.

The open gear lubricant composition of this invention can be formulated by mixing in any convenient way the base oil component having a viscosity in the previously recited range with the synthetic fluid component having a viscosity in the previously recited range to produce a blend having a viscosity between about 20 to 900 cSt @40-C, preferably between about 50 to 700 cSt @40-C, most preferably between ~ about 100 to 200 cSt @40-C. The thickener is introduced by chemically I reacting or mechanically dispersing thickener components in the base oil/synthetic fluid/high molecular weight polymer blend for from about 1 to about 8 hours or more (preferably from about 3 to about 6 hours) followed by heating at elevated temperature (e.g., from about 140-C to about 225-C, depending upon the particular thickener used) until the initial thickener formation and/or dispersion of the thickener in the blend is complete. In some cases (e.g. a simple lithium grease), a preformed thickener can be used. The mixture is then cooled to ambient temperature (typically about 60-C) during which time the high molecular weight copolymer and other additives if any are added. The ~'''`';~ . .
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`-` 2134798 high molecular weight polymer and the other additives can be added together or separately in any order. Once the proper proportions of the spec~fic components to produce the base oil/synthetic fluid blend having the desired viscosity and base oil/synthetic fluid/high molecular weight polymer blend having the desired lubricating fluid component viscosity as previously recited, have been determined, the individual component constituting ingredients of additional batches of the same final product can be combined in any order.

Thus, it is often desirable to first manufacture or disperse the thickener in the base oil component before adding the synthetic fluid component (this is dependent on the choice of the synthetic and the ratio of base oil to synthetic fluid. Thus, the synthetic fluid might be added after the high temperature phase of the reaction.

The base oil soluble high molecular weight polymer component could be added along with the base oil (or the base oil/synthetic fluid blend) prior to the formation or disperslon of the thickener and the high temperature phase. The polymer might also be added after the thickener formation over the range of temperatures from 225 to about 60-C, usually prior to the addition of the other additives at 60-C.
This depends upon the solubility characteristics of the polymer and the form in which it is added to the grease (i.e. as a liquid or as a solid crumb, etc.).

The components of the open gear lubricating composition can be mixed, blended, or milled in any number of ways which can readily be selected by one skilled in the art. Suitable means include external mixers, roll mills, internal mixtures, Banbury mixers, screw extruders, augers, colloid mills, homogenizers, and the like.

As previously stated, the high molecular weight polymer in an amount ranging from O to 5 wt% is added so as to insure that in the resulting formulation, the lubricant fluid component viscosity without thickener or other additives present is at least 320 cSt @40-C, preferably at least 460 cSt @40-C, most preferably at least 680 cSt @40-C. It is preferred that in all cases a quantity of high molecular _.. ... .
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., 213~798 weight polymer is present, e.g., 0.5 to 5 wt% polymer, more preferably 1 to 3 wtX polymer.

The Apparent Viscosity of the fully formulated product (including thickener and any additives and solid lubricants employed) must be less than about 20,000 Poise @ -30-C (at 20 seC~l shear rate as determined by ASTM D 1092, preferably below about 10,000 Poise @
-30-C (at 20 sec~l), more preferably below about 5,000 Poise @ -30-C
(at 20 sec-l), but greater than about 500 Poise @ -30-C, (at 20 seC-l) .

This invention will be further understood by reference to the following examples which include non-limiting examples of the present invention and, where indicated, comparative examples.

Examples ~d: `

Comparative Example 1 Lubricating greases of the following compositions were prepared:

GREASE A B C
COMPOSITION, wt%
Lithium 12-hydroxystearate 3.80 4.2 4.7 60 SUS e100-F Naphthen;c Oil (8-10 cSt @4~-C) 54.3 45.4 58.2 Polyisbutylene (800 cSt@ 100-C) - - 31.3 Polyalphaolefin (100 cSt@ 100C) - 45.4 Polyalphaolefin/polymethacrylate36.3 copolymer (450 cst@ 100C) Solid Lubricants 5.6 5.0 5.8 6rease Worked Penetration @25-C, mm~10 380(est) 385 378 Lubricating Fluid Component Viscosity cSt @40C 106.6 111.5 114.2 ~
cSt @100C 17.4 16.7 Grease Apparent Viscosity, 750 820 2500 Poise at -30-C and 20 sec-1 Shear Rate , The greases in this example all exhibit excellent low temperature -pumpability as determined by the results of the ASTM D 1092 grease Apparent Viscosity measurement at -30C. However, the viscosity of exclusively the lubricating fluid component blend contained in the final products is too low to provide adequate protection of large, slow moving gears under heavy loads. - .. `

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213 ~798 Comparative Example 2 A lubricating grease of the following composition was prepared:

GREASE D
.
COMPOSITION, wt%
Lithium 12-hydroxystearate 3.81 500 SUS @100'F Naphthenic Oil (-100 cSt @40-C)50.76 Polyisbutylene (800 cSt @100C) 29.81 2500 MI EVA Copolymer* 1.94 Zinc dialkyldithio-phosphate 1.48 Substituted thiodiazole 1.94 Sulfur/Phosphorus Extreme Pressure Agent 2.97 Barium Sulfonate 0.97 Glycerine 0.57 MoS2 2.90 Graphite 2.90 Grease Worked Penetration @25C, mm/10 360 Lubricating Fluid Component Viscosity cSt@ 40-C 1000 cSt@ 100-C
Grease Apparent Viscosity, Poise at 42000 -30'C and 20 sec-I Shear Rate *2500 Melt Index Ethylene Vinyl Acetate (a low molecular weight -copolymer) - -The grease of this example incorporates a 1000 cSt blend of synthetic polyisobutylene fluid and mineral oil. The product will provide ~ -adequate film thickness for gear protection but has poor low tempera- - -ture pumpability. The 2500 MI EVA copolymer used in this example has limited oil solubility at operating temperatures, especially at low -ambient, and will not contribute to the Lubricating Fluid viscosity under pumping conditions at -30-C. - -Comparative Example 3 -~

In this example a grease was prepared according to the procedure employed in Comparative Example 2, also omitting a high molecular weight polymer component. The lubricating fluid component viscosity was very good, exceeding 2,000 cSt @40'C but the Grease , - . :-, .-,,; . .

2~3~798 Apparent viscosity was unacceptably high at over 100,000 poise @-30C
and 20 sec-1 shear rate.

Grease E
Composition, wt%
Thickener Lithium 12-hydroxystearate 6.2 Base Oils 60 SUS ~100-F Naphthenic Oil (-8-10 cSt @40-C)26.45 Synthetic Fluids Polymethacrylate (1000 cSt @100-C) 57.6 Extreme Pressure/Anticorrosion Additives 5.5 Zinc Dialkyldithiophosphate 1.5 Antimony Dialkyldithiophosphate 0.25 Glycerine 0.5 Amine Antioxidant 0.5 Barium sulfonate 1.0 Solid Lubricants MoS2 3.0 Graphite 3.0 Grease Worked Penetration @25-C, mm/10 388 -.
Lubricating Fluid Component Viscosity - -cSt @40-C 2323 cSt @100-C 291 ~-Grease Apparent Viscosity, Poise at -30-C
and 20 sec-1 Shear Rate >100,000 ~.
ComDarative ExamDle 4 In the example a grease was formulated using the procedure of previous Comparative Example 3, also omitting a high molecular -~
weight polymer. The lubricating fluid component viscosity was very good, being over 900 cSt but the Grease Apparent Viscosity was unacceptable, exceeding 20,000 poise @ -30-C and 20 seC-l shear rate.

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213~798 , .
Grease F
Composition, wtX
Thickener Lithium 12-hydroxystearate 4.56 Base Oils 500 SUS @100-F Naphthenic Oil 32.42 Synthetic Fluids Polyalphaolefin/polymethacrylate copolymer (300 cSt @100-C) 51.52 Extreme Pressure/Anticorrosion Additives Zinc Dialkyldithiophosphate 1.5 Antimony Dialkyldithiophosphate 0.25 Glycerine 0.6 Amine Antioxidant 0.50 Barium sulfonate 1.0 Solid Lubricants - :-MoS2 2.97 --.
Graphite 2.98 -~
Grease Worked Penetration e25-C, mm/10 373 -:
Lubricating Fluid Component Viscosity : .-cSt @40-C 968 - :
cSt @100-C 73 . -Grease Apparent Viscosity, Poise at -30-C
and 20 sec-1 Shear Rate 22,000 .
Example 1 In this example, greases were prepared according to the present invention which included lubricating fluid component which -contained a mineral oil and a synthetic fluid together with a high molecular weight viscosity modifier. The composition formulations and ~- ~ .`.
low temperature pumpability performance are shown in the following : ~-table~

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GREASE G H
.
COMPOSITION, wt%
Lithium 12-hydroxystearate 4.5 4.1 60 SUS @100-F Naphthenic 0il(8-10cSt@40'C)57.20 44.10 Polyisbutylene (800 cSt @100-C) 30.70 21.20 Polyalphaolefin (100 cSt @100-C) - 14.80 Styrene-isoprene block copolymer 2.00 1.80 Zinc dialkyldithiophosphate 1.50 Substituted thiadiazole - 2.00 Sulfur/phosphorus extreme pressure agent - 3.00 Barium sulfonate - 1.00 Glycerine - 0.50 MoS2 2.8 3.0 Graphite 2.8 3.0 Grease Worked Penetration @25-C,mm/10 380(est) 358 Lubricating Fluid Component Viscosity cSt @40-C 1039 700 -~
cSt @100-C 106.1 Grease Apparent Viscosity, Poise at 4900 3500 -30 C and 20 sec-1 Shear Rate In these products the addition of a high molecular weight, soluble styrene-isoprene polymer provides lubricating fluid viscosity adequate for open gear lubrication while maintaining excellent low temperature -- -pumpability (Grease Apparent Viscosity). ~-~

Example 2 In this example, greases were prepared according to the present invention which included lubricating fluid component which ~ -contained a mineral oil and synthetic fluid components but not high molecular weight viscosity modifier. The composition formulations and low temperature pumpability performance are shown in the following table:

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GREASE I J
COMPOSITION, wt%
Thickener Lithium 12-hydroxystearate 2.9 4.8 Base 0ils 60 SUS @100-F Naphthenic 0il(~8-10cSt@40-C) - 26.85 100 SUS e100-F Naphthenic Oil (-20cSt@40-C)34.95 Synthetic Fluids Polyalphaolefin/polymethacrylate copolymer (450 cSt @100-C) 51.3 Polyalphaolefin/polymethacrylate copolymer -(300 cSt @100-C) - 58.8 ~-Extreme Pressure/Anticorrosion Additives Zinc dialkyldithiophosphate 1.5 1.5 :
Antimony Dialkyldithiophosphate 0.25 0.25 Glycerine 0.6 0.5 Amine Antioxidant 0.50 0.5 Barium sulfonate 1.0 1.0 Solid Lubricants MoS2 3.0 2.9 Graphite 3.0 2.9 -Grease Worked Penetration @25-C,mm/10 418 388 Lubricating Fluid Component Viscosity cSt e40-C 600 600 ~ -cSt e100-C 50 60 Grease Apparent Viscosity, Poise at 7800 5200 - --30-C and 20 sec-1 Shear Rate --- -The above greases were formulated using base oil/synthetic fluid blends which exceed the desired 320 cSt e40-c minimum. None of the -;
compositions contain high molecular weight polymer.

The Apparent Viscosity of greases I and J are within the broad range of Apparent Viscosity desired but falls short of the most preferred range (i.e. <5000 Poise maximum at -30-C which is the target for greases used in cooler climates (e.g. sustained periods of temperature below 20-C). The base oil/synthetic fluid blend viscosity is lower than the most preferred of the blend/high molecular weight polymer ~:; ' ' ' , , ~

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composite viscosity (i.e. 680 cSt @40-C minimum) but does fall within the broad operating ranges of the present invention.

Example 3 In this example, a grease was formulated employing a base component, a synthetic liquid component and a high molecular weight polymer component. The lubricating fluid component viscosity was 1421 cSt while the Grease Apparent viscosity was only 9,000 poise @-30-C
and 20 sec-1 shear rate. This example clearly shows that to achieve high lubricating fluid component viscosities while simultaneously securing a Grease Apparent viscosity such that the grease is easily pumpable, it is preferred that the formulated grease contain a high ~ -molecular weight polymer component. -', ' ~,' ~
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21~4798 Grease J
Composition, wtX
Thickener -Lithium 12-hydroxystearate 4.1 Base Oils 60 SUS @100-F Naphthenic Oil 43.10 Synthetic Fluids Polyalphaolefin/polymethacrylate copolymer (300 cSt eloo c) 21.10 Polyisobutylene (800 cSt @100-C) 14.90 High Molecular Weight Polymer Styrene-Isoprene Block Copolymer 2.5 ~ ~-Extreme Pressure/Anticorrosion Additives -Zinc Dialkyldithiophosphate 1.6 Antimony Dialkyldithiophosphate 0.25 Glycerine 0.4 Sulfur Phosphorus EP Agent 3.10 Substitute Thiadiazole 2.00 Barium sulfonate 1.0 Solid Lubricants MoS2 3.1 -~
Graphite 3.1 '- -`
Grease Worked Penetration @25-C, mm/10 375 Lubricating Fluid Component Viscosity --cSt @40-C 1421 ~--cSt @100-C 144 -Grease Apparent Viscosity, Poise at -30-C
and 20 sec-1 Shear Rate 9,000 :
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Claims

1. An open gear lubricant composition comprising:

(A) a base oil component having a viscosity of less than 220 cSt @40-C;

(B) one or more synthetic fluid components each having a viscosity of about 2 to 2000 cSt @100°C

wherein A and B are used in a ratio so that the combination A and B is a base oil blend having a viscosity of between about 20 to about 900 cSt @40°C;

(C) from O to 5 wt% of a base oil soluble high molecular weight polymer, based on the base oil blend and (D) from 1 to 20 wt% of a thickener wherein the resulting lubricant composition exhibits a lubricant fluid component viscosity of at least 320 cSt @40°C and a Grease Apparent viscosity of less than about 20,000 Poise @ -30°C at 20 sec-1 shear rate.

2. The open gear lubricant composition of claim 1 further containing:

(E) from 1 to 15 wt% of a solid lubricant; and, (F) from 0 to 10 wt% of additives selected from the group consisting of extreme pressure additives, anti-wear additives, anti-corrosion additives, anti-oxidant additives and mixtures thereof based on total weight of the lubricant composition.

3. The open gear lubricant composition of claim 1 or 2 wherein Component A, the base oil component, is a natural mineral oil boiling in the lubricating oil boiling range of about 200 to 800°C, and Component C, the base oil soluble high molecular weight polymer is present in an amount in the range 0.5 to 5.0 wt% based on the base oil blend.

4. The open gear lubricant composition of claim 3 wherein Component C, the base oil soluble high molecular weight polymer, is a polymer having a number average molecular weight of greater than 25,000.

5. The open gear lubricant composition of claim 4 wherein Component C, the base oil soluble high molecular weight polymer, is present in an amount in the range 1 to 3 wt% based on the base oil blend.

6. The open gear lubricant composition of claim 5 wherein Component C, the base oil soluble high molecular weight polymer, is a polymer having a number average molecular weight of greater than 100,000.

7. The open gear lubricant composition of claim 3 having a lubricant fluid component viscosity of at least 680 cSt @40°C and a Grease Apparent viscosity of less than about 10,000 Poise @-30°C at 20 sec-1 shear rate.