GB2506974A - Lubricant compositions - Google Patents

Abstract

A lubricant composition comprising (A) a non silicone base stock oil, and (B)a polydiethylsiloxane in an amount of from 1-60% by weight of the combined weight of (A) + (B) is provided and may be used as an automatic transmission fluid, a manual transmission fluid, an axle lubricant, a transaxle lubricant, an industrial gear lubricant, a circulating lubricant, an open gear lubricant, an enclosed gear lubricant, a hydraulic fluid a compressor fluid, in a gear box of a wind turbine or a grease.

Description

LUBRICANT COMPOSITIONS

10001] Disclosed herein are lubricant compositions comprising a non silicone base stock oil, and a polydiethylsiloxane.

10002] Lubricant oils and compositions are used to reduce friction and wear between moving elements or surfaces. The main component of lubricant oils and compositions is commonly referred to as a base stock. Base stocks are classified by the American Petroleum Institute (API) in five Groups, namely Groups I, II, Ill, IV and V. Lubricant base stocks include natural lubricating oils, synthetic lubricating oils, and mixtures thereof. Groups Ito Ill include base stocks derived from petroleum based oils, while Groups IV and V include synthetic base stocks including silicones.

10003] Silicones may be used in lubricant compositions in both critical (metal-to-metal) applications and non critical (plastic-to-plastic) applications mainly due to their good low and high temperature behaviour. They show chemical resistance, lubricity and thermal and oxidative stability.

IS 10004] Viscosity Index (VI) is an empirical, unit less number which indicates the rate of change in the viscosity of an oil within a given temperature range, usually between 40°C and 100°C. The Viscosity Index is defined as the gradient of kinematic viscosities of a material, between 40°C and 100°C. When the Viscosity Index is low (below 100) the fluid exhibits a relatively large change of viscosity with temperature. When the Viscosity Index is high (above 150), the fluid exhibits relatively little change of viscosity with temperature. In a variety of applications, a high or very high Viscosity Index is preferred.

10005] The chemical composition of the lubricant base stocks from Group I, Group II and Group Ill can vary substantially, for example regarding the proportions of aromatics, paraffinics. and naphthenics. The degree of refining and the source materials used to produce the lubricant base stock generally determine this composition. Lubricant base stock from Group I, Group II and Group Ill include paraffinic mineral oils and naphthenic mineral oils. Mineral oils of viscosities ranging of from 4.0 to 8.0 mPa.s, at 100°C, (ASTM D445-12) have a Viscosity Index ranging of from 80 to 120, or 140 for high performance grades (ASTM D2270-lOel).

10006] The materials of Groups I, II and Ill are divided into groups based on sulphur content and Viscosity Index as follows: * Group I base stock oils generally have a Viscosity Index of between about 80 to 120 and contain greater than about 0.03% by weight of sulfur and/or less than about 90% by weight of satuiated organic components (hereafter referred to as saturates" * Group II base stock oils generally have a Viscosity Index of between about 80 to 120, and contain less than or equal to about 0.03% by weight of sulfur and greater than or equal to about 90% by weight of saturates.

* Group Ill oils generally have a Viscosity Index greater than about 120 and contain sulphur in an amount less than or equal to about 0.03% weight and greater than about 90% weight of saturates.

10007] Group IV is composed of polyalphaolefins (PAO) which are hydrogenated oligomers obtained from the oligomeiization of alphaolefin rnonomeis. These alphaolefin monomers may have from about 4 to about 30 or from about 4 to about 20 or from about 6 to about 12 carbon atoms, such as hexene, octene or decene. The oligomers may be dimers, trimers, tetramers, pentamers, and hexamers of the alphaolefin monomer.

10008] Group V base stocks include base stocks not included in Groups l-IV such as polyinternal oletins (PlO); polyalkylene glycols (RAG); alkylated aromatics such as alkylated benzenes, e.g. dodecylbenzene, tetradecylbenzene, di-nonylbenzene, and di-(2-ethylhexyl)benzene; polyphenyls e.g. biphenyls, terphenyl and alkylated polyphenyls; synthetic esters such as esters of dicarboxylic acids e.g. dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, dUsooctyl azelate, dUsodecyl azelate, dioctyl phthalate, didecyl phthalate and dieicosyl sebacate, esters of carboxylic acids, polyolesters, e.g. neopentyl glycol, trimethylolethane, trimethylpropane, pentaerythritol, dipentaerythritol and tripentaerythritol; phosphate esters, e.g. tricresyl phosphate, trioctylphosphate, and diethyl ester of decylphosphonic acid; silicones; and further polyisobutylene (PIB) and halogenated hydrocarbons.

10009] Other lubricant base stocks include those of vegetal and animal origin, such as rapeseed oil, castor oil and lard oil.

10010] Silicones (Group V) may be used in lubricant compositions in both critical (metal-to-metal) applications and non critical (plastic1o-plastic) applications mainly due to their good low and high temperature behaviour. They show chemical resistance, lubricity, thermal stability and oxidative stability.

10011] However in respect of lubrication under high loads, silicones, with the exception of halogenated silicones, are generally both inferior to organic base oil as described above and are typically more costly than organic base stocks.

10012] RU2 194741 discloses lubricating oil intended for stable functioning of parts and mechanisms comprising steel-steel friction couples based on liquid polyethylsiloxanes (65- 85%) with molecular weight 500-1 00 and viscosity 40-50 mm2/s and containing 14.25- 33.25% poly-alpha-olefins with average degree of oligomerization 7-8 and molecular weight 900-1200 and 0.75-1.75% dioctyl sebacate, for lowered freezing temperature and improved lubrication property.

10013] There is a need tor lubricant compositions with a Viscosity Index (VI) of above 150, alternatively above 200, and good metal-to-metal lubrication, at acceptable cost. Currently Viscosity Index values of lubricant compositions are increased through the addition of additives typically refeired to as viscosity index Improvers (VI Improvers). VI Improvers are currently typically high molecular weight organic polymers but their use does not always increase the Viscosity Index to the desired values for the purpose concerned and due to their high molecular weight said VI Improvers often lack shear stability.

10014] There is also a need for lubricant compositions with improved load carrying in metal-metal lubrication applications, because more stable lubricant films will ultimately reduce the wear in such applications. The load carrying of a lubricant film can for example be assessed by determining the Load Carrying Capacity (LCC) in accordance with the test method defined in ASTM D 5706-05.

10015] There is also a need for lubricant compositions having high levels of Viscosity Index improvement combined with good lubrication.

10016] Disclosed herein is a lubricant composition comprising (A) a non silicone base stock oil, (B) a polydiethylsiloxane in an amount of from 1-60% by weight of the combined weight of (A)+(B).

10017] Also disclosed is a method to lubricate metal-to-metal surfaces with the aforesaid composition.

10018] Further disclosed is the use of the lubricant composition as hydraulic fluid, transmission fluid, gear fluid and/or compressor fluid.

10019] The non silicone base stock (Component (A)) is an oil that is mainly based on hydiocarbons and potentially nitrogen-, oxygen-and sulfur-containing hydrocarbon derivatives, from any of API Groups Ito V discussed above and mixtures thereof, excluding silicone lubricant oils and forms a non-homogeneous composition with the aforementioned component (B) when mixed therewith.

10020] Component (A) may for example be:- (i) mineral oil based lubricant base stock oils having a wide variety of aromatics, paraffinics, and naphthenics, said mineral oils having viscosities ranging from 4.0 to 8.0 rnPa.s, at 100°C, (ASTM D445-12) have a Viscosity Index ranging from 80 to 120, or for high performance grades (ASTM D2270-lOel); (H) polyalphaolefins (PAO), which are hydrogenated oligomers obtained from the oligomerization of alphaolefin monomers. These alphaolefin monomers may have fiom about 4 to about 30 or from about 4 to about 20 or from about 6 to about 12 carbon atoms, such as hexene, octene or decene. The oligomers may be dimers, trimers, tetramers, pentamers, and hexamers of the alphaolefin monomer. When the PAO is based on alphaolefin monomers of 6 to 16 carbon atoms, its viscosity may range from 1.7 to 100 mPa.s, at 100°C (ASTM 0445-1 2), and its viscosity index (VI) may range from 120 to 150 (ASTM D2270-lOel). Typically, the PAO may have a viscosity of from about 2 to about 15, or from about 3 to about 12, or from about 4 to about 8 mPa.s, at 1000 C (ASIM D445-12). Examples of PAOs include poly-alpha-olefins 4 mPa.s, at 100°C, poly-alpha-olefins 6 mPa.s, at 100° C, and mixtures thereof.

(Ui) polyinternal olefins (PlO), hydrogenated (saturated) olefin oligomers usually manufactured from linear or cyclic internal olefins, obtained from cracked paraffinic base stock oils. The internal olefin may have from about 10 to 30 or from 10 to 20 or from 12 to 16 carbon atoms, such as the mixtures C13-14, 015-17 or 014-19. After oligomerization, dimers and trimers may be obtained. Typically! the PIG may have a viscosity of from about 2to about 15, or from about 3to about 12, or from about4to about 8 mPa.s, at 100° C (ASTM 0445-12). Polyinternal olefins have a Viscosity Index to 20 units lower than polyalphaolefins of equivalent viscosity using test method (ASTM D2270-1 Del) and (iv) polyalkylene glycols (PAG) Polyalkylene glycols include homopolymers, block and random copolymers of ethylene oxide, propylene oxide or butylene oxide. Examples of polyalkylene glycols include polyethylene glycol, polypropylene glycol, polymers of butylene oxide, copolymers of ethylene oxide and propylene oxide (diols or monobutyl ethers), polymers of propylene oxide (dimethyl ethers).

10021] Component (A) may additionally or alternatively consist of mixtures of the above.

10022] Component A has a viscosity in the range of from ito 10000 mPa.s at 40°C, preferably 2 to 1000 mPa.s at 40°C. ASTM D445-12).

10023] Alternatively Component A ( or A mixed with B) may be formulated into a grease after addition of a thickener to one of the non-silicone base stock oils described in API Groups Ito V discussed above and mixtures thereof.

10024] The processes to obtain the lubricant base stock oils are known by the skilled in the art and will therefore not be described here any further.

10025] Component (A) is present in the lubricant composition of from 4Owt% to 99.0 wt%, alternatively bOwt% to 99wt%, alternatively 6Owt% to 95wt%, alternatively BOwt% to 95wt% based on the total weight of (A) + (B), which is lOOwt%.

10026] The polydiethylsiloxane is to be understood as mainly based on silicon-oxygen atom bonds forming the backbone of the polymer including, but are not limited to, silicone fluids, liquid silicone resins, silicone waxes.

IS 10027] Siloxanes generally conform to a polymeric backbone consisting of groups of the forriiula RmSO4m/2 in which m is zero, 1, 2, 3 or 4 and where m has an average value of from 1.98 to 2.5 per molecule and the siloxane has a degree of polymerisation 2. In one embodiment at least 80% of R groups on the polymer backbone are ethyl groups, alternatively substantially all, alternatively all R groups on the backbone are ethyl groups.

Terminal groups or branching points may however, include non ethyl groups.

10028] Typically the polydiethylsiloxane will have general formula Et Ri O-Si-R2 Et v wherein FT is ethyl and wherein R1, R2 and S3 are independently selected from alkyl groups aryl groups or alkylaryl groups, of 1 to 45 carbon atoms, alternatively of ito 30 carbon atoms and further alternatively ito 16 carbon atoms with v being an integer.

100291 Linear polydiethylsiloxanes will have a value of v of from 3 to 10000, alternatively from to 1000. Linear polydiethylsiloxane may have viscosities ranging from 0.5 to 600 000 mPa.s. at 25°C using a cone/disk viscometer (Physica MCR 301) at constant shear rate of D = 8.7sj.

10030] The polydiethylsiloxane may be branched or contain other siloxanes units to depress crystallization.

10031] The polydiethysiloxane can be obtained by ring-opening polymerization of diethylcyclosiloxanes. Alternatively the polydiethylsiloxane can be obtained by polycondensation of silanes containing at least one ethyl group. The silanes used in the preparation can be a mixture of silanes. The silanes can contain up to 10% of none ethyl functional silanes such as but not limited to methyltrimethoxysilane or tetraethoxyorthosilicate.

10032] The polydiethylsiloxane (B) may have a viscosity at 40°C of from 0.5 to 100,000 mPa.s, alternatively of from I to 10.000 mPa.s, alternatively 20 to 1.000 mPa.s using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of D = 8.7sj.

10033] The polydiethylsiloxane (B) is present of from lwt% to 6Owt%, alternatively lwt% to SOwt%, alternatively Swt% to 2Owt%, alternatively 5% to lOwt% based on the total weight of (A) 1-(B), which is lOOwt%.

10034] When the polydiethylsiloxane (B) is present in an amount lower than 1% the desired improvements are not obtained. When the polydiethylsiloxane (B) is present in an amount greater than 6Owt%, the performance drops to values approximating to those obtained with 100% weight polydiethylsiloxane which is not a very good performing lubricant (as shown e.g. in Load Carrying Capability ([CC) data) as such.

100351 Lubricant additives may be used to impart or improve certain properties to the lubricating composition. Such additives include friction modifiers, anti-wear additives, extreme pressure additives, seal swelling agents, rust and corrosion inhibitors, thickeners, Viscosity Index improvers "other than (By', pour point depressants, anti-oxidants, free-radical scavengers, hydroperoxide decomposers, metal passivators, surface active agents such as detergents, emulsifiers, demulsifiers, defoamants, compatibilizers, dispersants, and mixtures thereof.

10036] Further additives include deposit control additives, film forming additives, tackifiers, antimicrobials, additives for biodegradable lubricants, haze inhibitors, chromophores, limited slip additives.

10037] Examples of friction modifiers include long-chain fatty acids and their derivatives, molybdenum compounds, aliphatic amines or ethoxylated aliphatic amines, ether amines, alkoxylated ether amines, acylated amines, tertiary amines, aliphatic fatty acid amides, aliphatic carboxylic acids, aliphatic carboxylic esters, polyol esters, aliphatic carboxylic ester-amides, imidazolines, aliphatic phosphonates, aliphatic phosphates, aliphatic thiophosphonates, aliphatic thiophosphates.

10038] Examples of anti-wear additives and extreme pressure additives include organosulfur and organo-phosphorus compounds, such as organic polysulfides among which alkylpolysulfides; phosphates among which trihydrocarbyl phosphate, dibutyl hydrogen phosphate, amine salt of sulfurized dibutyl hydrogen phosphate, dithiophosphates; dithiocarbamates dihydrocarbyl phosphate; sulfurized oletins, such as sulfurized isobutylene, and sulfurized fatty acid esters.

10039] Examples of seal swell agents include esters, adipates, sebacates, azeealates, phthalates, sulfones such as 3-alkoxytetraalkylene sulfone, substituted sultolanes, aliphatic alcohols of 8 to 13 carbon atoms such as tridecyl alcohol, alkylbenzenes, aromatics, naphthalene depleted aromatic compounds, mineral oils.

IS 10040] Examples of rust and corrosion inhibitors include monocarboxylic acids such as octanoic acid, decanoic acid and dodecanoic acid; polycarboxylic acids such as dimer and trimer acids from tall oil fatty acids, oleic acid, linoleic acid; thiazoles; triazoles such as benzotriazole, decyltriazole, 2-mercapto benzothiazole; thiadiazoles such as 2,5-dimercapto- 1,3,4-thiadiazole, 2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazole; metal dithiophosphates; ether amines; acid phosphates; amines; polyethoxylated compounds such as ethoxylated amines; ethoxylated phenols; ethoxylated alcohols; imidazolines; aminosuccinic acids.

10041] Examples of thickeners include metallic soaps such as lithium soaps, silica, expanded graphite, polyurea, clays such as hectorite or bentonite.

10042] In some instances, when thickened, the lubricant composition may become a grease composition.

10043] Examples of Viscosity Index improvers "other than (B)" include polymethacrylates, olefin copolymers, polyisoalkylene such as polyisobutylene, styrene-diene copolymers, and styrene-ester copolymers such as styrenemaleic ester.

10044] Examples of pour point depressants include wax-alkylated naphthalenes and phenols: polymethacrylates, styrene-ester copolymers.

10045] Examples of anti-oxidants include phenolic antioxidants such as 2,6-di-tert- butylphenol, tertiary butylated phenols such as 2,6-di-tert-butyl-4-methylphenol, 4,4'- methylenebis(2,6-di-tert-butylphenol),2,2'-methylenebis(4-methyl6-ter t-butylphenol), 4,4'-thiobis(2-rnethyl-6-tert-butylpheno; mixed methylene-bridged polyalkyl phenols; aromatic amine antioxidants; sulfurized phenolic antioxidants; organic phosphites; amine derivatives such as p-, p'-dioctyldiphenylamine, N,N'-di-sec-butylphenylenediamine, 4-isopropylaminodiphenylamine, phenyl-.alpha.-naphthyl amine, phenyl-.alpha.-naphthyl amine, ring-alkylated diphenylamines; bisphenols; cinnamic acid derivatives.

10046] Examples of free-radical scavengers include zinc dialkyl dithiophosphates, hindered phenols, and alkylated arylamines.

10047] Examples of hydroperoxide decomposers include organo-sulfur compounds and organo-phosphorus compounds.

10048] Examples of metal passivators include poly-functional (polydentate) compounds, such as ethylenediaminetetraacetic acid (EDIA) and salicylaldoxirne.

10049] Examples of surface active agents such as detergents, dispersants, emulsifiers, demulsifiers include alkali metal or alkaline earth metal salts of organic acids such as magnesium sulfonate, zinc sulfonate, magnesium phenate, zinc phenate. lithium sulfonate, lithium carboxylate, lithium salicylate, lithium phenate, sulfurized lithium phenate, magnesium sulfonate, magnesium carboxylate, magnesium salicylate, magnesium phenate, sulfurized magnesium phenate, potassium sulfonate, potassium carboxylate, potassium salicylate, potassium phenate, sulfurized potassium phenate; common acids such as alkylbenzenesulfonic acids, alkylphenols, fatty carboxylic acids, polyamine, polyhydric alcohol derived polyisobutylene derivatives.

10050] Examples of defoamants include polysiloxanes, polyacrylates and styrene ester polymers.

10051] Examples of compatibilizers include aromatic hydrocarbons such as 1-methyl-naphthalene, aromatic ethers such as diphenyl ether or anisole (methyl phenyl ether), long chain alcohols such as nonyl phenol, octanol and decanol.

10052] Examples of dispersants include alkenylsuccinimide such as polyisobutylene succinimide, N-substituted polyisobutenyl succinimides such as polyisobutenyl succinimide-polyethylenepolyamine, succinates, succinate esters, alkyl methacrylate-vinyl pyrrolidinone copolymers, alkyl methacrylate-dialkylaminoethyl niethacrylate copolymers, alkylmethacrylate-polyethylene glycol methacrylate copolymers, polystearamides, high molecular weight amines, phosphoric acid derivatives such as bis-hydroxypropyl phosphorate.

10053] Some additives may possess multiple properties and provide for a multiplicity of affects. For example, graphite and molybdenum disulfide may both be used as friction modifiers and extreme pressure additives or functionalized soaps may be used to thicken but also provide extreme pressure and antiwear performances to greases. This approach is well known by the person skilled in the art and need not be furthei elaborated herein.

10054] An additive may be used alone or in combination with other additives.

10055] When present in the lubricant composition of the invention, the sole or multiple additive(s) may be used ata level of from 0 to lOwt%, alternatively 0.1 to 5wt%, based on the total weight of the lubricant composition. Thickeners to produce greases may be used at a level of fiom 5 to 50%wt alternatively from 5 to 35%wt based on the total weight of the lubricant grease composition.

10056] The lubricant composition is produced by mixing the lubricant base oil and the silicone oil and the optional additives, by conventional mixing means, optionally with heating.

10057] The lubricant composition is homogeneous. Homogeneity of the composition is considered at 25CC, after mixing, and optional heating, is interrupted.

10058] A homogeneous composition is intended to mean herein a composition where the lubricant base oil and the polydiethylsiloxane are compatible or miscible and form a monophasic system. A homogeneous composition may be hazy, clear or opaque. The intimate blend of the 2 components is uniform and posses the same properties throughout.

The compatibility of mixtures may be assessed using ASTM D7155-1 1: Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils.

10059] Examples of homogeneous compositions include polydiethylsiloxane with polyalphaolefin, polydiethylsiloxane with mineral oil.

10060] Lubricating compositions may be used in a variety of applications where friction occurs between rubbing surfaces. The surfaces may be plastic or metal.

10061] Types of friction include sliding, rolling, static, kinetic, stick-slip, solid (dry), boundary, mixed, wear, erosion, elasto-hydrodynamic frictions.

10062] The present invention includes a method to lubricate a metal-metal surface comprising i. obtaining a lubricant composition as hereinbefore described, and H. lubricating the metal-metal surface with said lubricant composition 10063] The present lubricant composition may be used in any system that includes machine elements that contain gears of any kind and roller bearings. Examples of such systems include electricity generating systems, industrial manufacturing equipments such as paper, steel and cement mills hydraulic systems, automotive drive trains, aircraft propulsion systems, etc. 10064] Further systems include crankcases, 2-stroke engines, 4-stroke engines, diesel engines, internal combustion engines, gears for manual or differential transmissions, industrial lubricants, hydraulic, compressor, turbine, metal working, metal forming, lubrication grease, solid. The lubricant composition may alternatively be used as a gear oil for wind turbines.

10065] Further systems also include traction and torque systems.

10066] The lubricant composition may alternatively be used as an automatic transmission fluid, a manual transmission fluid, an axle lubricant, a transaxle lubricant, an industrial gear lubricant, a circulating lubricant, an open gear lubricant, an enclosed gear lubricant, a hydraulic fluid, a compressor fluid, or a grease.

10067] The lubricant composition may alternatively be used as a gear oil for wind turbines.

IS 10068] Operating temperatures for the use of the lubricant composition, meaning the temperatures at which the lubricant composition may be used for prolonged time (also called service temperatures), range of from -55°C to +200°C. Short term peak temperature may be higher.

Examples

Test Methods 10069] Viscosity Index (VI) 10070] Viscosity Index is measured/calculated using ASTM D 2270-1 OE: Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 and 100DC:_.

Kinematic viscosity (mm2ls) = dynamic viscosity (mPa.s) material density The dynamic viscosity is determined by a cone/disk viscometer (Physic? MCR 301) at constant shear rate of D = 8.7s1 and at the two different required temperatures: 40°C and 100° C. 10071] The density may be measured using glass pycnometer according to DIN 51757 (Procedure V2). Ideal mixing is assumed for blends of materials, meaning that the density of the blend can be calculated from the respective values of the ingredients. The values of dynamic viscosities were subsequently used to calculate kinematic viscosities using the material densities tabulated below. The calculated kinematic viscosities were then used to calculate Viscosity Index as per formula: Viscosity lndex= [((antilog N) -1)10.00715 + 100] where yN = H/U, Y = kinematic viscosity at 100°C of the oil whose viscosity index is to be calculated, H = kinematic viscosity at 40°C of a 100 Viscosity Index oil with the same viscosity at 100°C as the unknown, U = kinematic viscosity at 40°C of the oil whose viscosity index is to be calculated.

10072] The Load Carrying Capability (LCC) properties of the lubricant compositions being assessed were determined in accordance with ASTM D 5706-05 Standard test method for determining extreme pressure properties of lubricating greases using a high-frequency, linear-oscillation (SRV) test machine'. The SRV test machine may be used to determine load carrying and wear properties and coefficient of friction of lubricating greases at selected temperatures and loads specified for use in applications where high-speed vibrational or start-stop motions are present for extended periods of time under initial high Hertzian point contact pressures. This method has found application in qualifying lubricating greases used in constant velocity joints of front-wheel-drive automobiles and for lubricating greases used in roller bearings. This method may also be used for determining a fluid lubricant's ability to protect against wear and its coefficient of friction under similar test conditions.

100731 In the following examples a lubricating fluid was evaluated instead of lubrication greases; a steel cylinder was used instead of a steel ball; frequency was 10 Hz instead of 50Hz. The measurements were carried out at 40°C using 1mm stroke. The load was increased in increments of 50N every two minutes up to a maximum load of 2000N.

10074] Wearing properties or lubrication performance may be evaluated by standard test method DIN 51 350-3 Testing of lubricants in the Shell four-ball tester'. The Shell Four Ball Tester (FBT) is a testing device used to determine welding and metal loads as well as different friction and wear characteristics of lubricants. The standard test consists of a rotating ball of a ball bearing being pressed onto three similar but immobile balls while applying a load of 1 OON, 400N and 800N for 1 hour test duration. Wear is determined by optically measuring the formed calotte (the worn depression area).

100751 This testing device is especially common in the lubricant industry where it is used for routine product development and quality control testing. The friction torque can be recorded continuously.

10076] The testing was done according to DIN 51350-3 and the wear scar is reported as the average of the three steel balls in mm.

10077] The lubricant composition of the present invention is characterized by a Viscosity Index »= 180, alternatively ? 200, alternatively ? 250.

10078] The lubricant composition of the present invention is characterized by a load carrying capability according to the procedure described above. LCC »= 800N, SRV-load »= 1000N alternatively? 1200N, alternatively? 1500N (ASTM D 5706-05).

EXAMPLES

10079] The following examples are included to demonstrate preferred embodiments of the invention. All percentages are in wt. %.

MATERIALS

10080] PDES: polydiethylsiloxane obtained from GNIIChTEOS, having a viscosity of 344 mPa.s at 20°C determined using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of D = 8.7s1; IS 10081] PAO: polyalphaolefin (PAC SpectraSynTM 6 from ExxonMobil Chemicals) having a typical viscosity of 30.3 mm2/s at 40°C (Producers datasheet dated 27 February 2012) VI type PiB: Polyisobutylene Viscosity Improver: commercial material Hitec® 7389, from Afton Chemical Corporation, with a typical viscosity of 176 mm2/s at 100°C (Producers datasheet) 10082] VI type OCP: Olefin Copolynier Viscosity Improver: commercial material Hitec® 5704, from Afton Chemical Corp., with a typical viscosity of 1100 mm2/s at 100°C 10083] The density of the materials was measured using a glass pycnometer according to DIN 51757 (Procedure V2). The following parameters for the densities p in g/ml (for a given temperature p= a-(b x Temperature (°C)) were obtained using linear regression which were then used to calculate the densities at 40 and 100°C. a b

PAO 0.8343 0.0006 PDES 1.0149 0.0007 10084] For the blends ideal mixing was assumed meaning that the density of the blend can be calculated from the respective values of the ingredients.

10085] Blending: The blends were prepared by adding a total of 50g of materials to a glass bottle and shaking them until a homogenous mixture was obtained.

10086] The viscosity, viscosity index and the wear properties i.e. Load Carrying Capability (LCC) were measured for different compositions. The results are shown in the following tables; values for the individual components are given as a reference.

Example I a: PDES + PAO PDES PAD [CC (wt%) (wt%) (N) O 100 450 95 2000 90 2000 60 2000 40 1500 20 750 10 1200 0 250 10087] Example la shows that mixtures according to the invention containing PDES have an LCC much higher than the pure oils. The effect can be already seen with a 5% wt % addition level of PDES into the PAD.

Example 1 b: PDES + PAO PDES PAD Viscosity at Viscosity at Viscosity (Wt%) (Wt%) 40°C 100°C Index (rnPa.s) (mPa.s) 0 100 --143* 80 30.91 6.62 207 60 38.27 8.3 222 40 50.76 12.5 271 20 82.34 19.33 267 10 118.93 28.08 285 10088] Example lb shows that mixtures according to the invention containing PDES have much higher VI values than 100% PAD (Viscosity Index 143 from supplier's datasheet).

Example 2 a: PDES + mineral oil PDES Mineral Oil LCC (Wt%) (Wt%) (N) 0 100 1000 95 1400 90 2000 80 1800 60 1050 40 1100 20 450 5 450 0 250 10089] Example 2 a shows that compositions as hereinbefore described containing POES and mineral oil have an LCC much higher than 100% mineral oil. The effect can be seen at 5% addition level of PDES into the mineral oil.

Example 2 b: PDES + mineral oil PDES Mineral Oil Four ball (Wt%) (Wt%) wear scar at 400N load (mm) 0 100 1.727 95 0.730 90 1.122 80 1.538 60 1.160 40 0.941 20 2.112 10 3.564 5 nm* 0 10090] Example 2b shows that that compositions as hereinbefore described containing PDES and mineral oil have a lower wear scar in the four ball test than the pure mineral oil (nm stands for non measurable, load is too high to run the test).

Comparative examples 1-6: 10091] PAO Blends with organic VI Improvers were prepared using the commercial Hitec® 5704, Hitec® 7389 and polyisobutylenes (PiB) -Comparative examples 1-6 10092] PAO Blends with organic VI Improvers were prepared using the commercial Hitec® 5704 and Hitec® 7389 Comparative VI improver Viscosity at Viscosity at Viscosity example 40°C 100°C Index (mPa.s) (mPa.s) 1 5% Hitec® 5704 40.4 7.1 168 2 10%Hitec®5704 60.1 9.6 167 3 20%Hitec®5704 113.8 18.2 199 4 5% Hitec® 7389 30.7 6.1 186 10% Hitec®7389 37.6 7.1 184 6 20% Hitec® 7389 57.4 10.4 196 10093] Comparative examples 1-6 indicate that the commercial viscosity improvers are less efficient than the disclosed siloxanes disclosed in Examples 1-10. Furthermore, the comparative viscosity improvers do not allow achieving viscosity indices above 200 when used with polyalphaolefin. The Viscosity Index of the blends where calculated from the dynamic viscosity using the densities of the pure PAO at 40°C and 100°C.

Comparative example 7 and example 3: Comparative VI improver Viscosity at -35°C

example (mPa.s)

a 10%Hitec5lO4 9520 b 10%Hitec7389 6175 Example 3 10% PDES 2790 10094] The comparative example 7 and b show that a PDES used at 10% in PAO has a low temperature viscosity significantly lower than commercial VI improvers at the same addition level.

Claims (6)

1. CLAIMSA lubricant composition comprising (A) a non silicone base stock oil, and (B) a polydiethylsiloxane in an amount of from 1-60% by weight of the combined weight of (A) + (B).
2. 2. A lubricant composition according to claim 1 where (A) is selected from any non silicone lubricant base oil of Group Ito V, as per the American Petroleum Institute (API) classification of lubricant base oils or mixtures thereof.
3. 3. A lubricant composition according to claim 1 or 2 where (A) is selected from mineral oil, polyalphaolefins, polyinternal olefins, polyolesters, polyalkylene glycols and mixtures or greases thereof.
4. 4. A lubricant composition according to any of the preceding claim where (B) is Et Ri r R2__5i4_o_Si 0-Si L Et wherein Ft is ethyl, R1, R and R3 are independently selected from alkyl, aryl or alkylaryl of ito 20 carbon atoms and v is an integer> 0.
5. 5. A lubricant composition in accordance with claim 4 wherein each Ri, R2 and R3 are individually selected from methyl groups, ethyl groups and phenyl groups.
6. 6. A lubricant composition according to any of the preceding claim where (A) is present of from 4Owt% to 99wt%, 1. A lubricant composition according to any of the preceding claims where (B) is present of from 5Owt% to lwt%, based on the total weight of (A) + (B).8. A lubricant composition according to any of the preceding claim further comprising an optional additive (C) selected from the group consisting of friction modifiers, anti-wear additives, extreme pressure additives, seal swelling agents, rust and corrosion inhibitors, thickeners, Viscosity Index improvers "other than (B)", pour point depressants, anti-oxidants. free-radical scavengers, hydroperoxide decomposers, metal passivators, surface active agents such as detergents, emulsifiers, demulsifiers, defoamants, compatibilizers, dispersants, deposit control additives, film forming additives, tackifiers, antimicrobials, additives for biodegradable lubricants, haze inhibitors, chromophores, limited slip additives, and mixtures thereof.9. A lubricant composition according to claim 8 characterised in that optional additive (C) is present at a level of from 0 to lOwt%, alternatively 0.1 to 5wt%, based on the total weight of the lubricant composition.10. A lubricant grease comprising the composition of any preceding claim.11. A lubricant composition according to any of the preceding claim wherein the LCC is above 800N when determined in accordance with ASIM D 5706-05.12. A lubricant composition according to any of the preceding claim wherein the Viscosity Index is above 180 when determined in accordance with ASTM D 2270-bE.13. A lubricant composition according to any of the preceding claim wherein viscosity at - 35°C is below 5000mPa.s when determined by a cone/disk viscometer (Physica® MOR 301) at constant shear rate of D = 8.7s-I.14. A method to lubricate metal-metal surfaces comprising Obtaining a lubricant composition in accordance with any preceding claim, and U Lubricating the metal-metal surface with said lubricant composition.15. The use of a lubricant composition in accordance with any one of claims Ito 13 as an automatic transmission fluid, a manual transmission fluid, an axle lubricant, a transaxle lubricant, an industrial gear lubricant, a circulating lubricant, an open gear lubricant, an enclosed gear lubricant, a hydraulic tluid a compressor fluid, in a gear box of a wind turbine or a grease.16. A lubricant composition as hereinbefore described with reference to the examples.