GB2506973A - Lubricant compositions - Google Patents

Abstract

A non-homogeneous lubricant composition comprising (A) a non-silicone lubricant base stock and (B) a polysiloxane selected from polydialkylsiloxane, polyalkylphenylsiloxane, polyalkylarylsiloxane, polytrifluoropropylmethyl siloxanes wherein component B is present in the range of 1-70% weight of the total of (A) +(B) and B has a viscosity of at least 5mPa.s at 40°C. The composition is intended for use as or in 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, an hydraulic fluid, a compressor fluid, a gear oil for wind turbines or a grease.

Description

LUBRICANT COMPOSITIONS

[0001] Disclosed herein are non-homogenous lubricant compositions comprising a non-silicone lubricant base stock and a polysiloxane selected from polydialkylsiloxane, polyalkylphenylsiloxane, polyalkylarylsiloxane, polytrifluoropropylmethyl siloxanes.

[0002] 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.

[0003] Viscosity Index (VI) is an empirical, unit less number which indicates the rate of change in the viscosity of an oil in a given temperature range, usually 40°C between 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.

[0004] The chemical composition of the 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 D445-1 2) have a Viscosity Index ranging of from 80 to 120, or 140 for high performance grades (ASTM D2270-lOel).

[0005] 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 saturated 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.

[0006] Group IV base stocks are composed of polyalphaolefins (PAO) which are hydrogenated oligomers obtained from the oligomerization of alphaolefin monomers.

These alphaolefin monomers may have from about 4 to about 30 or from about 4 to about 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.

[0007] Group V base stocks include base stocks not included in Groups l-IV such as polyinternal olefins (PlO); polyalkylene glycols (PAG); 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, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate and dieicosyl sebacate, esters of carboxylic acids, polyol esters, 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 (P1 B) and halogenated hydrocarbons.

[0008] Other lubricant base stocks include those of vegetal and animal origin, such as rapeseed oil, castor oil and lard oil.

[0009] Silicones (Group V) 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, thermal stability and oxidative stability.

[0010] 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.

[0011] GB1224885 claims a composition comprising a mineral oil and 0.1 to 15 per cent by weight thereof of an oil-miscible diorganopolysiloxane as a viscosity index improver in which a major proportion of the organo groups are methyl groups and the remainder of the organo groups are substituted or unsubstituted alkyl, alkaryl or aralkyl groups having at least 6 and not more than 30 carbon atoms in amount sufficient to render it miscible with mineral oil.

[0012] EP0177825 discloses lubricating composition based on organopolysiloxane miscible with mineral oil, which have a pour point (measured according to DIN 51583) below-15°C.

[0013] US3634246 discloses lubricant compositions containing a major amount of triaryl phosphate and a minor amount of a silicone polymer containing at least 40 mole percent phenylsiloxane units. Exemplary is a blend of 60 volume percent tricresylphosphate and volume percent of a 50-50 copolymer of dimethylsiloxane units and phenylmethylsiloxane units.

[0014] US4190546 discloses a traction fluid comprising from 50 to 90% wt of a naphthenic hydrocarbon or mixture of naphthenic hydrocarbons, from 8 to 40% wt of a silicone fluid and from 2 to 10% wt of a co-solvent which ensures complete miscibility between the naphthenic hydrocarbon and silicone fluid, the percentages being by weight of the three components. The silicone fluid improves the low temperature properties of the fluid without substantial damage to the good traction properties of the naphthenic hydrocarbons.

Preferred co-solvents are aromatic hydrocarbons or aromatic ethers.

[0015] EP0283922 discloses a homogeneous blend of a dimethylsiloxanet alkylmethylsiloxane copolymer with a hydrogenated polyalphaolefin based on oligomers of decene-1. The blend serves as a base fluid which has a viscosity-temperature profile and flash point suitable for use in a -54°C to 135°C fire-resistant hydraulic fluid having particular utility in military aircraft hydraulic systems.

[0016] US4449415 discloses traction fluids containing certain siloxane components and, optionally, certain cycloaliphatic hydrocarbon components. These traction fluids possess high traction coefficients and good low temperature viscosity properties which make these fluids ideally suited for use in traction drive systems subjected to wide operating temperature conditions.

[0017] US7553429 discloses simple dimethylsilicone fluids of the proper viscosity/molecular weight distribution to modify the low temperature properties of cycloaliphatic hydrocarbon fluids. Addition of the dimethylsilicone fluid to cycloaliphatic fluids improves their low temperature performance without degrading the requisite elastohydrodynamic shear strength properties. Low viscosity dimethylsilicone lubricating fluids combined with cycloaliphatic hydrocarbon fluids are suitable for use in infinitely variable transmissions and other traction-drive transmission providing good low temperature flow properties and high elastohydrodynamic shear strength [0015] There is a need for 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 referred 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.

[0019] 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 ability 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.

[0020] There is also a need for lubricant compositions having high levels of Viscosity Index improvement combined with good lubrication. Surprisingly we have found that non-homogenous lubricant compositions show desirable properties.

[0021] Disclosed herein are non-homogenous lubricant compositions comprising (A) a non-silicone lubricant base stock; (B) a polysiloxane selected from polydialkylsiloxane, polyalkylphenylsiloxane, polyalkylarylsiloxane, polytrifluoropropylmethyl siloxanes wherein component B is present in the range of 1-70% weight of the total weight of(A) --(B) and B has a viscosity of at least 5 mPa.s at 40°C.

[0022] The viscosity of (B) is measured using a cone/disk viscometer at constant shear rate of D = 8.7s1. The specific type used herein was a Physica® MCR 301.

[0023] Also disclosed is a method to lubricate metal-to-metal surfaces with the above composition.

[0024] Further disclosed is the use of the non-homogeneous lubricant composition as hydraulic fluid, transmission fluid, gear fluid and/or compressortluid.

[0025] The lubricant composition is non homogeneous. For the avoidance of doubt a homogeneous composition is a composition where the lubricant base stock and the silicone oil are compatible or miscible and form a monophasic system. A homogeneous composition may be hazy, clear or opaque. The intimate blend of the 2 oils is uniform and possesses the same properties throughout. The compatibility of mixtures may be assessed using ASTM D7155-11: Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils. In contrast, a "non homogeneous" composition is defined herein as a composition in which the lubricant base oil and the silicone oil form a biphasic system upon rest. A non homogeneous composition will be characterized by a varying composition of the blend throughout the container. Whilst a non homogeneous system may be rendered homogenous by shaking, heating or addition of a compatibilizer, or a combination thereof, it will return to a non homogeneous state upon interruption of the shaking or heating. When a compatibilizer is used, the duration of improved homogeneity will depend on the effectiveness of the compatibilizer.

[0026] Examples of non homogenous compositions include polydimethylsiloxane with mineral oil, polydiethylsiloxane with polyol ester, polymethyloctylsiloxane with polyalkylene glycol, polymethyloctylsiloxane with polyol esters polymethyltrifluoropropylsilaxne with polyalphaolefine.

[0027] The non silicone base stock (Component (A)) is an oil that is mainly based on hydrocarbons 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.

[0025] 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 mPa.s, at 100°C, (ASIM D445-12) have a Viscosity Index ranging from 80 to 120, or 140 for high performance grades (ASTM D2270-1 0e1); (U) polyalkylene glycols (FAG) including 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); or (Hi) polyol esters such as neopentyl glycol, trimethylolethane, trimethylpropane, pentaerythritol, dipentaerythritol, tripentaerythritol. Component (A) may additionally or alternatively consist of mixtures of the above.

[0029] Component (A) has a viscosity in the range of from ito 10000 mPa.s at 40°C, alternatively 2 to 10000 mPa.s at 40°C, alternatively 2 to 1000 mPa.s at 40°C (ASTM 0445-12).

[0030] Alternatively Component (A) 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.

[0031] 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.

[0032] Component (A) is present in the lubricant composition of from 3Owt% to 99.0 wt%, alternatively SOwt% to 99wt%, alternatively 6Owt% to 95wt%, alternatively 9Owt% to 95wt% based on the total weight of (A) ÷ (B), which is lOOwt%. Hence when (A) is present in the above amounts (B) is present in an amount of 100 wt% -Wt% of (A).

[0033] Polysiloxanes (Component (B)) are polymers in which silicon-oxygen atom bonds form the backbone of the polymer. Polydialkylsiloxanes include, but are not limited to, silicone fluids, liquid silicone resins, silicone waxes.

[0034] Linear polydialkylsiloxanes generally conform to the general formula: Me r R2 Si-1---o Si 0-Si 0-Si 0 Siç-R2 L Men -R5v Met in which Me is a methyl group and each R1, each R2 and each R3 is individually selected from hydrocarbon groups having from 1 to 45 carbon atoms, each R5 is individually selected from a hydrocarbon group containing from 1 to 18 carbon atoms e.g. linear or branched alkyl groups, phenyl groups and/or alkylaryl groups; and each P4 group is a hydrocarbon groups having from 2 to 45 carbon atoms, n is zero or an integer, v is zero or an integer and t is zero or an integer and wherein n ÷ v ÷ t >1; and that when v is > zero, n is zero and t is zero and that when P zero, v is zero and n is zero or an integer.

[0035] The organic group of each R1, each P2, each P3 and each P4 may independently be alkyl groups having at least 2 alkyl groups (ethyl, propyl, isopropyl, butyl, octyl, nonyl, tetradecyl, octadecyl); cycloalkyl groups (cyclohexyl, cyclohepty; alkenyl groups (vinyl, hexenyl); aryl groups (phenyl, diphenyl, naphthyl); alkaryl groups (tolyl, xylyl, ethylphenyl); aralkyl groups (benzyl, phenylethyl).

[0036] Further organic groups which may be used for R1, R2, S3 and/or p4 include those hydrocarbon groups with at least 2 carbon atoms wherein one or more hydrogen atoms has been replaced with another substituent, also referred to as organyl groups. Examples of such substituents include, but are not limited to, halogen atoms (chlorine, fluorine, bromine, iodine); halogen atom containing groups such as haloalkyl groups (chloromethyl, periluorobutyl, trifluoroethyl, and nonafluorohexyl) and haloaryl groups (monochlorophenyl, dibromophenyl, tetrachlorophenyl, monofluorophenyl); oxygen atoms; oxygen atom containing groups such as carboxyl, carbinol, ester, ether, acrylic groups and polyoxyalkylene groups (polyoxyethylene, polyoxypropylene, polyoxybutylene); nitrogen atoms; nitrogen atom containing groups such as nitrile, amino, amido, cyano, cyanoalkyl and urethane groups; sulphur atoms; sulphur atom containing groups such as sulphide, sulphone, sulphate, sulphonate and mercapto groups; phosphorus atoms; phosphorus atom containing groups such as phosphate, phosphate and phosphonate groups.

[0037] In one alternative, each p1, each p2, and each p3 may be independently selected from alkyl groups, of 1 to 45 carbon atoms, alternatively of 1 to 30 carbon atoms and further alternatively 1 to 16 carbon atoms or phenyl groups containing 6 to 16 carbon atoms and each p4 is independently an alkyl group having from 2 to 16 carbon atoms.

[0035] In one alternative all p5 groups may be ethyl groups in which case the formula given above may be re-written as follows: Me Et r 1

I I

R2___Si1_o_Si 0-Si o_siJ_o__Siç_R2 L Me -Et v MeJt [0039] In a further alternative the polysiloxanes (component (B)) may be in the form of random copolymers, such as ABA or ABn type block copolymers in which each R1, each R2, each R3 and each R4are independently as hereinbefore described. The polysiloxane (B) has a viscosity at 40°C of at least 5 mPa.s, alternatively from 5 to 100.000 mPa.s, alternatively of from Sto 10,000 mPa.s, alternatively lOto 1.000 mPa.s (using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of D = [0040] Examples of linear polysiloxanes include polyalkylalkylsiloxane polymers such as polymethyloctylsiloxane, polymethylphenylsiloxane; polyalkylarylsiloxanes; having a viscosity at 40°C of from 2 to 10.000 mPa.s, alternatively of from 10 to 1.000 mPa.s (using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of 0 = 8.7s1).

[0041] Branched siloxanes which may be utilized as component (B) include, for the sake of example, silicone resins. Silicone resins generally contain two or more of the following groups (R13SiOij2)a (R22SiO 2!2))b (R3Si0312) and (Si0412) d with R1, R2 and R3 independently represent an alkyl group containing from 1 to 8 carbon atoms, an awl group, a carbinol group, an alkoxy group (preferably methoxy or ethoxy) or an amino group, 0,05 «= a «= 0,5; 0 «= b «= 0,3; c »= 0; 0,05 «= d «= 0,6, and a+b+c+d1 (with a, b, c and d being the mole fractions), having a viscosity at 40°C of at least 5 mPa.s, alternatively from 5 to 10.000 mPa.s (using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of 0 = 8.7s), alternatively of from 20 to 1.000 mFa.s.

[0042] The polysiloxane (B) may be selected from polydiethylsiloxane, polydimethylsiloxane, polydimethylmethylalkylsiloxane, polymethylalkylsiloxane [00431 The polysiloxane (B) is present in an amount of from lwt% to 7Owt%, alternatively lwt% to 40wt%, alternatively Swt% to 2Owt%, alternatively 5% to lOwt% based on the total weight of(A) + (B). which is lOOwt%. Hence! the total wt % of (A) + (B) will always be 100%wt.

[0044] 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 (B)', pour point depressants, anti-oxidants, free-radical scavengers, hydroperoxide decomposers, metal passivators, surface active agents such as detergents, ernulsifiers, demulsifiers, defoamants, compatibilizers, dispersants, and mixtures thereof.

[0045] Further additives include deposit control additives, film forming additives, tackifiers, antimicrobials, additives for biodegradable lubricants, haze inhibitors, chromophores, limited slip additives.

[0046] 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 tally acid amides, aliphatic carboxylic acids, aliphatic carboxylic esters, polyol esters, aliphatic carboxylic ester-amides, imidazolines, aliphatic phosphonates, aliphatic phosphates, aliphatic thiophosphonates, aliphatic thiophosphates.

[0047] Examples of anti-wear additives and extreme pressure additives include organosulfur and organo-phosphorus compounds, such as organic polysultides among which alkylpolysulfides; phosphates among which trihydrocarbyl phosphate, dibutyl hydrogen phosphate, amine salt of sulfurized dibutyl hydrogen phosphate, dithiophosphates; dithiocarbamates dihydrocarbyl phosphate; sulfurized olefins, such as sulfurized isobutylene, and sulfurized fatty acid esters.

[0048] Examples of seal swell agents include esters, adipates, sebacates, azeealates, phthalates, sulfones such as 3-alkoxytetraalkylene sulfone, substituted sulfolanes, aliphatic alcohols of 8 to 13 carbon atoms such as tridecyl alcohol, alkylbenzenes, aromatics, naphthalene depleted aromatic compounds, mineral oils.

[0049] 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.

[0050] Examples of thickeners include metallic soaps such as lithium soaps, silica, expanded graphite, polyurea, clays such as hectorite or bentonite.

[0051] In some instances, when thickened, the lubricant composition may become a grease composition.

[0052] 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.

[0053] Examples of pour point depressants include wax-alkylated naphthalenes and phenols, polymethacrylates, styrene-ester copolymers.

[0054] Examples of anli-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-methyl-6-tert-butylphenol); 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.

[0055] Examples of free-radical scavengers include zinc dialkyl dithiophosphates, hindered phenols, and alkylated arylamines.

[0056] Examples of hydroperoxide decomposers include organo-sulfur compounds and organo-phosphorus compounds.

[0057] Examples of metal passivators include poly-functional (polydentate) compounds, such as ethylenediaminetetraacetic acid (EDIA) and salicylaldoxime.

[0058] 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 sultonate, 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.

[0059] Examples of defoamants include polysiloxanes, polyacrylates and styrene ester polymers.

[0060] As hereinbefore indicated the lubricant composition is non homogeneous. A non homogeneous system may be rendered temporarily homogenous by addition of a compatibilizer but these non homogenous compositions will return to non homogeneous state upon interruption of the shaking or heating. When a compatibilizer is used, the duration of improved homogeneity will depend on the effectiveness of the compatibilizer -temporarily or over a longer period of time.

[0061] Compatibilizers may be surfactants or co-solvents. Homogeneity may be obtained through emulsification, dispersion or any other means known by the person skilled in the art. Emulsification techniques are known by the person skilled in the art and will not be further exemplified herein. 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.

[0062] 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 methacrylate copolymers, alkylmethacrylate-polyethylene glycol methacrylate copolymers, polystearamides, high molecular weight amines, phosphoric acid derivatives such as bis-hydroxypropyl phosphorate.

[0063] Some additives may possess multiple properties and provide for a multiplicity of effects. For example, graphite and molybdenum disulfide may both be used as friction modifiers and extreme pressure additives orfunctionalized 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 further elaborated herein.

[0064] An additive may be used alone or in combination with other additives.

[0065] When present in the lubricant composition of the invention, the sole or multiple additive(s) may be used at a level of from Oto lOwt%, alternatively 0.1 to Swt%, based on the total weight of the lubricant composition. Thickeners to produce greases may be used at a level of from 5 to 25%wt based on the total weight of the lubricant grease composition.

[0066] The lubricant composition is produced by mixing the lubricant base stock (A) and the polysiloxane (B) and the optional additives, by conventional mixing means, optionally with heating.

[0067] Lubricating compositions may be used in a variety of applications where friction occurs between rubbing surfaces. The surfaces may be plastic or metal.

[0068] Types of friction include sliding, rolling, static, kinetic, stick-slip, solid (dry), boundary, mixed, wear, erosion, elasto-hydrodynamic frictions.

[0069] The present invention includes a method to lubricate metal-metal surfaces comprising i. obtaining a lubricant composition as hereinbefore described; and ii. lubricating the metal-metal surface with said lubricant composition.

[0070] 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. [0071] 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.

[0072] The lubricant composition may alternatively be used as a gear oil for wind turbines.

[0073] Further systems also include traction and torque systems.

[0074] 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, an hydraulic fluid, a compressor fluid, or a grease.

[0075] 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 Viscosity Index (VI) [0076] VI is measured/calculated using ASTM D 2270-bE: Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 and 100°C.

Kinematic viscosity (mm2/s) = dynamic viscosity (mPa.s) material density [0077] The dynamic viscosity is determined by a cone/disk viscometer (Physict MCR 301) at constant shear rate of D = 8.7s1 and at the two different required temperatures: 40°C and 100°C.

[0078] 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)/0.00715 + 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.

[0079] The Load Carrying Capability ([CC) 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.

[0080] 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 SON every two minutes up to a maximum load of 2000N.

[0081] 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 bearing being pressed onto three similar but immobile balls while applying a load of lOON, 400N and BOON for 1 hour test duration. Wear is determined by optically measuring the formed calotte (the worn depression area).

[0082] 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.

[0083] 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.

[0084] The lubricant composition of the present invention is characterized by a Viscosity Index »= 180, alternatively »= 200, alternatively »= 250.

[0085] The lubricant composition of the present invention is characterized by a load carrying capability according to the procedure described above. LCC »= 800N, SRV-load »= bOON, alternatively »= 1200N, alternatively »= 1500N (ASTM D 5706-05).

[0056] All percentages are in wt. %.

[0087] Materials: -PDMS: polydimethylsilanes having a typical viscosity of SOcst (50 mm2/s) at 25°C determined using a glass capillary viscosimeter -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 -PAO polyalphaolefin (PAO SpectrasynTM 6 from Exxon Mobil Chemicals) having a typical viscosity of 30.3 mm2/s at 40°C (Producers datasheet dated 27 February 12) -Mineral oil: Nynas® NS-1 00 (severely hydrotreated base oil obtained from Nynas AB) having a typical viscosity of 96 mm2ls at 40°C (Producers datasheet, dated 3 March 2008) -PMOS 1: polymethyloctylsiloxane, prepared by reacting a trimethylsilyl terminated methylhydrogen siloxanes (having a viscosity of approx 30mPa.s at 20°C) with an excess of 1-octene using a Pt catalyst at 120°C. The reaction was monitored by IR spectroscopy until the SiH stretch peak (at about 2180cm4) had disappeared. The excess of 1-octene was then removed by vacuum distillation and a clear oil having a viscosity of 1130 mPa.s at 20°C was obtained using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of D = 8.7s1 -PMOS 2: polymethyloctylsiloxane, prepared by reacting a trimethylsilyl terminated methylhydrogen siloxanes (having a viscosity of approx 6 mPa.s at 20°C) with an excess of 1-octene using a Pt catalyst at 120°C. The reaction was monitored by IR spectroscopy until the SiH peak had disappeared. The excess of 1-octene was then removed by vacuum distillation and a clear oil having a viscosity of 170 mPa.s at 20°C was obtained using a cone/disk viscometer (Physica® MCR 301) at constant shear rate of D = 8.7s1 -Polyol ester: polyol ester based on dipentaerithrytol and C5/C8/C10 acids: commercial material Hatcol® 2926, from Hatco, with a typical viscosity of 53 mm2/s (ASTM 0-445) at 40°C (Producers datasheet, dated (08/04/06) -Polyglycol: polyalkylene glycol B01/40 from Clariant, with a typical viscosity of 58 mm2/s at 40°C (Producers datasheet) -Viscosity Index type PiB: Polyisobutylene Viscosity Improver: commercial material Hitec® 7389, from Afton Chemical Corporation, with a typical viscosity 01176 mm2ls at 100°C (Producers datasheet) -Viscosity Index type OCP: Olefin Copolymer Viscosity Improver: commercial material Hitec® 5704, from Afton Chemical Corp., with a typical viscosity of 1100 mm2/s at 100° C [0088] 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 PMOS 1 0.9216 0.0006 PMOS 2 0.9161 0.0007 The values for PDMS are calculated using an equation from the Polymer Data Handbook (1999 Oxford University Press) to be 0.957g/ml at 40°C and 0.905 g/ml at 100°C.

[0059] For the blends ideal mixing was assumed meaning that the density of the blend can be calculated from the respective values of the ingredients.

[0090] 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.

[0091] 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.

Examples

Example I a Polydimethylsiloxane (PDMS) + PAO PDMS(Wt%) PAO(Wt%) LCC(N) 0 100 450 95 2000 90 2000 80 1800 60 1850 40 1750 20 650 10 400 5 350 0 300 [0092] The Example la shows that mixtures according to the invention containing PDMS have an LCC much higher than 100% PAO. The effect can be clearly identified at 5% addition level of PDMS.

Example lb PDMS and PAO PDMS (Wt %) PAO (Wt %) Viscosity at 40°C Viscosity at 100°C Viscosity (mPa.s) (mPa.s) Index 0 100 143* 95 27.8 5.7 188 90 29.1 7.6 276 80 39.6 8.8 234 60 39.7 9.5 257 40 38.4 9.5 266 20 36.7 12.3 369 10 35.0 11.7 368 5 36.1 14.5 435 0 35.0 16.7 502 [0093] Example lb shows that mixtures according to the invention containing PDMS have much higher Viscosity Index values than the 100% PAO. *: the Viscosity Index value for FAO at 143 is provided by the supplier.

Example 2 a: PDMS + mineral oil PDMS (Wt %) Mineral Oil (Wt %) LCC(N) 0 100 1000 95 2000 90 2000 80 1550 60 1150 40 1400 20 850 10 500 0 300 [0094] Example 2a shows that mixtures according to the invention containing PDMS have an LCC much higher than 100% mineral oil. The effect can be already seen at 5% addition level of PDMS in the mineral oil.

Example 2 b: PDMS + mineral oil PDMS (Wt %) Mineral Oil (Wt %) Four ball wear scar at 400N load (mm) 0 100 1.727 95 1.147 90 0.926 60 0.989 40 1.125 20 0 [0095] Example 2b shows that that compositions as hereinbefore described containing PDMS 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).

Example 3: PMOS I + Polyol ester PMOS 1 (Wt %) Polyol ester (Wt %) LCC (N) 90 1250 50 2000 0 1300 [0096] Example 3 shows that mixtures according to the invention containing PDMS have LCC of above 1000N Example 4: PMOS 2 ÷ Polyol ester FMOS 2 (Wt %) Folyol ester (Wt %) LCC(N) 90 1500 50 1350 10 1400 0 1450 [0097] Example 4 shows that mixtures according to the invention containing PMOS2 have an [CC of above 1000N Example 5: PDES + Polyol ester PDES (wt %) Polyol ester (wt %) LCC (N) 90 1500 50 1500 10 450 0 250 [0098] Example 5 shows that mixtures according to the invention containing FOES have a load carrying (LCC) than 1000N Example 6: PDES + Polyglycol FOES (wt%) Polyglycol (Wt %) LCC (N) 90 2000 50 1900 10 700 0 250 [0099] Example 6 shows that mixtures according to the invention containing FOES have an [CC higher than 1000N Comparative examples 1-6 (homocienous mixtures) [0100] PAO Blends with organic VI Improvers were prepared using the commercial Hitec® 5704 and Hitec® 7389 Comparative VI improver Viscosity at 40°C Viscosity at 100°C Viscosity example (mPa.s) (mPa.s) Index 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 [0101] Comparative examples 1-6 indicate that the commercial viscosity improvers are less efficient than the disclosed siloxanes disclosed in Examples 1-6. 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 density of the pure PAO.

Claims (14)

1. CLAIMS1. A non-homogeneous lubricant composition comprising (A) a non-silicone lubricant base stock (B) a polysiloxane selected from polydialkylsiloxane, polyalkylphenylsiloxane, polyalkylarylsiloxane, polytrifluoropropylmethyl siloxanes wherein component B is present in the range of 1-70% weight of the total of (A) ÷(B) and B has a viscosity of at least 5mPa.s at 40°C.
2. 2. A lubricant composition according to claim 1 where base stock (A) is a polyester, polyol ester or polyglycol.
3. 3. A lubricant composition according to claim 1 where base oil (B) is selected from polydimethylsiloxane, polydimethylsiloxane, a methylalkylsiloxane wherein the alkyl groups have at least 2 carbons, methylalkyaryllsiloxanes with the akylaryl having at least 8 carbons, a polymethylphenylsiloxane and a polymethyl trifluoropropylsiloxane
4. 4. A lubricant composition according to claim 1 where component (A) has a viscosity in the range of from 2 to 10000 mPa.s at 40°C.
5. 5. A lubricant composition according to any preceding claim where (A) is present of from 50wt% to 99wt%, based on the total weight of (A) ÷ (B).
6. 6. A lubricant composition according to any preceding claim where (B) is present of from SOwt% to lwt%, based on the total weight of (A) + (B).
7. 7. A lubricant composition according to any 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.
8. 8. A lubricant composition according to any preceding claim wherein each optional additive (C) is present at a level of from 0.01 to lOwt%, based on the total weight of the lubricant composition.
9. 9. A lubricant grease comprising the composition of any preceding claim.
10. 10. A lubricant composition according to any preceding claim wherein the LCC is above 1000N when determined in accordance with ASIM 0 5706-05.
11. 11. A lubricant composition according to any preceding claim wherein the VI is above when determined in accordance with ASTM D 2270-bE.
12. 12. A lubricant composition according to any preceding claim wherein viscosity at -35°C is below 5000mPa.s when determined by a cone/disk viscometer (Physica® MCR 301) at constant shear rate of D = 8.7s1.
13. 13. A method to lubricate metal-metal surfaces comprising Obtaining a lubricant composition in accordance with any one of claims 1 to 12, and ii Lubricating the metal-metal surface.
14. 14. The use of a lubricant composition in accordance with any one of claims 1 to 12, 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, an hydraulic fluid a compressor fluid, a gear oil for wind turbines or a grease.