EP2504415A1

EP2504415A1 - Lubricating composition containing viscosity modifier combination

Info

Publication number: EP2504415A1
Application number: EP10784639A
Authority: EP
Inventors: Andrew Gelder; David Price; Gareth Brown; Simon Evans
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 2009-11-24
Filing date: 2010-11-23
Publication date: 2012-10-03
Also published as: CA2781880A1; JP2013512313A; US20120329694A1; CA2781880C; AU2010324872B2; US20160145524A1; KR20120117988A; BR112012012454A2; CN106010746A; AU2010324872A1; JP5820389B2; AU2016259404A1; JP2015187283A; WO2011066242A1; CN102712868A; KR101821831B1

Abstract

The present invention relates to a lubricating composition containing (a) an oil of lubricating viscosity, (b) a star polymer and (c) a substantially linear polymer with a weight average molecular weight of 45,000 or less. The invention further provides a method of lubricating a mechanical device, typically a manual transmission with the lubricating composition. The invention further provides for the use of the lubricating composition to provide a number of benefits including lower operating temperatures and fuel economy

Description

TITLE

Lubricating Composition Containing Viscosity Modifier Combination

FIELD OF INVENTION

[0001] The present invention relates to a lubricating composition containing (a) an oil of lubricating viscosity, (b) a star polymer and (c) a substantially linear polymer with a weight average molecular weight of 45,000 or less. The invention further provides a method of lubricating a mechanical device, typically a manual transmission with the lubricating composition. The invention further provides for the use of the lubricating composition to provide a number of benefits including lower operating temperatures and fuel economy.

BACKGROUND OF THE INVENTION

[0002] Viscosity index improvers are known to be added to lubricating oil compositions to improve the viscosity index of the lubricant. Typical viscosity index improvers include polymers of methacrylates, acrylates, olefins (such as copolymers of alpha-olefms and maleic anhydride and esterified derivatives thereof), or maleic anhydride-styrene copolymers, and esterified derivatives thereof. The viscosity index improvers tend to incorporate ester functional groups in pendant/grafted/branched groups. The ester functional groups may be derived from linear alkyl alcohols with 1 to 40 carbon atoms. Recent attempts have been made to produce viscosity index improvers from copolymers of alpha-olefms. However, such viscosity index improvers have poor shear stability, too high a viscosity at low temperature, poor fuel economy, and poor non-dispersant cleanliness.

[0003] In addition, lubricants capable of performing at lower viscosity (in, for instance, driveline devices) typically provide increased fuel economy (thus improving corporate average fuel efficiency (CAFE), NEDC (European Driving Cycle), or FTP-75 (Federal Test Procedure), or Japanese test cycle (JC-08)). Conversely, higher viscosity fluids contribute to elevated gear and transmission operating temperatures, which are believed to reduce fuel economy and diminish durability. [0004] International publication WO 2007/127660 discloses a lubricating composition containing a star polymer, a phosphorus -containing compound and an extreme pressure agent.

[0005] International publications WO2006/047398 and WO2006/047393 : WO2006/047398 discloses that the star polymer may be derived from atom transfer radical polymerisation (ATRP), nitroxide mediated polymerisation, anionic polymerisation and reversible addition fragmentation (RAFT). WO2006/047393 discloses lubricating compositions having linear and star poly(meth)acrylates derived from RAFT polymerisation.

[0006] International Patent Application PCT/US2009/052028 discloses a lubricating composition containing a copolymer comprising units derived from monomers (i) an α-olefm and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer, prior to esterification has a reduced specific viscosity of up to 0.08.

[0007] US Patent Application 2008/0085847 discloses a lubricating oil composition comprising a major amount of oil of lubricating viscosity, and a viscosity index (VI) improver composition comprising a first polymer comprising an amorphous ethylene- olefin copolymer or ethylene-a-olefm-diene terpolymer having a crystallinity of not greater than about 1.0%; and a second polymer comprising a star polymer, the arms of which are derived from diene, and optionally vinyl aromatic hydrocarbon monomer, wherein the star polymer has a Shear Stability Index (SSI) of from about 1% to about 35% (30 cycle).

SUMMARY OF THE INVENTION

[0008] The inventors of this invention have discovered that a lubricating composition, method and use as disclosed herein is capable of providing at least one of improved oxidative stability, reduced mechanical device operating temperatures, increased mechanical device durability, improved shear stability index, improved viscosity index, improved low temperature viscometrics and improved high temperature viscometrics. [0009] In one embodiment the invention provides a lubricating composition comprising (a) an oil of lubricating viscosity, (b) a star polymer, and (c) a substantially linear polymer with a weight average molecular weight of 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 12,000 to 20,000.

[0010] The substantially linear polymer may have a shear stability index of less than 25 (or 15 or less, or 10 or less, or 0 to 10, or 0 to 5) as measured by procedure described in CEC test CEC-L-45-99 entitled "Viscosity Shear Stability of Transmission Lubricants (Taper Roller Bearing Rig)" or test method DIN 51350-6- KRL/C.

[0011] In one embodiment the invention provides a lubricating composition comprising (a) an oil of lubricating viscosity, (b) a star polymer, and (c) a substantially linear polymethacrylate polymer with a weight average molecular weight of 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 12,000 to 20,000.

[0012] In one embodiment the invention provides a lubricating composition comprising (a) an oil of lubricating viscosity, (b) a star polymer, and (c) a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol.

[0013] In one embodiment the invention provides a lubricating composition comprising (a) an oil of lubricating viscosity, (b) a star polymer, and (c) a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer, prior to esterification has a reduced specific viscosity of up to 0.2, or up to 0.15, or up to 0.10, or typically up to 0.08.

[0014] In one embodiment the invention provides a lubricating composition comprising:

(a) an oil of lubricating viscosity,

(b) a star polymer, wherein the star polymer may be a polymethacrylate or polyacrylate (typically a polymethacrylate), the star polymer may be derived from a monomer composition comprising: (i) 50 wt % to 100 wt % (or 65 wt % to 95 wt %) of an alkyl methacrylate, wherein the alkyl group of the methacrylate has 10 to 30, or 10 to 20, or 12 to 18, or 12 to 15 carbon atoms;

(ii) 0 wt % to 40 wt % (or 5 wt % to 30 wt %) of an alkyl methacrylate, wherein the alkyl group of the methacrylate has 1 to 9, or 1 to 4 carbon atoms (for example methyl, butyl, or 2-ethylhexyl); and

(iii) 0 wt % to 10 wt % (or 0 wt % to 5 wt %, or 0.1 to 2 wt %) of a dispersant monomer (may be referred to as either oxygen-containing compound, or nitrogen-containing monomer and typically nitrogen-containing monomer); and

(c) copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer, prior to esterification has a reduced specific viscosity of up to 0.2, or up to 0.15, or up to 0.10, typically up to 0.08.

[0015] In one embodiment the invention provides a lubricating composition comprising an oil of lubricating viscosity, a star polymer and a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer is an interpolymer, and wherein the interpolymer has a reduced specific viscosity (prior to esterification) of up to 0.08, or 0.02 to 0.08 (or 0.02 to 0.07, 0.03 to 0.07 or 0.04 to 0.06).

[0016] The copolymer comprising units derived from monomers (i) an a- olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position may be defined in terms of weight average molecular weight or by RSV. Typically the weight average molecular weight is measured on the final esterified copolymer, optionally capped with an amine. The weight average molecular weight may be 5000 to 35,000 (approximately 0.15 RSV), or 5000 to 20,000, or 13,000 to 18,000. [0017] The copolymer reduced specific viscosity (RSV) is measured by the formula RSV = (Relative Viscosity - l)/Concentration, wherein the relative viscosity is determined by measuring, by means of a dilution viscometer, the viscosity of a solution of 1.6 g of the copolymer in 100 cm of acetone and the viscosity of acetone at 30 °C. A more detailed description of RSV is provided below. The RSV is determined for the copolymer of an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof before esterification with the primary alcohol branched at the β- or higher position.

[0018] In different embodiments the primary alcohol branched at the β- or higher position may have at least 12 (or at least 16, or at least 18 or at least 20) carbon atoms. The number of carbon atoms may range from at least 12 to 60, or at least 16 to 30.

[0019] In one embodiment the invention provides a lubricating composition comprising an oil of lubricating viscosity, a star polymer and a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer may be an interpolymer, and wherein the interpolymer has a reduced specific viscosity of up to 0.08, or 0.02 to 0.08 (or 0.02 to 0.07, 0.03 to 0.07 or 0.04 to 0.06) .

[0020] In one embodiment the copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position described above further comprises units from a monomer having at least one of an ester group and a nitrogen containing group (such as amino-, amido- and/or imido- group), typically sufficient to provide 0.01 wt % to 1.5 wt % (or 0.02 wt % to 0.75 wt %, or 0.04 wt % to 0.25 wt %) nitrogen to the copolymer.

[0021] In one embodiment the invention provides for a method of lubricating a mechanical device comprising supplying to said mechanical device (typically a driveline device) a lubricating composition as disclosed herein. In one embodiment the mechanical device may be a manual transmission. [0022] In one embodiment the invention provides for the use of a lubricating composition as described herein to provide a lubricant (typically a manual transmission lubricant) with at least one (or at least two, or up to all) of acceptable or improved shear stability, acceptable or improved viscosity index control, acceptable or improved low temperature viscosity, acceptable or improved fuel economy, and acceptable or improved device operating temperatures. Typically the lubricant may be used in a driveline device such as a manual transmission.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention provides a lubricating composition, method and use as disclosed herein.

Star Polymer

[0024] The lubricating composition of the invention contains a star polymer (or the star polymer may also be referred to as a radial polymer). The star polymer may be present in the compositions described herein at 0.1 wt % to 30, or 0.1 wt % to 20 wt %, wt %, or 2 wt % to 30 wt %, or 5 wt % to 20 wt %, or 8 wt % to 15 wt %. The star polymer may also be present at 0.2 wt % to 15 wt %, or 0.5 wt % to 10 wt % , or 1 wt % to 8 wt % of the lubricating composition.

[0025] A detailed description of the star polymer disclosed herein may also be described in WO 2007/127660 (published on 8 November 2007, by Baker et al. and assigned to The Lubrizol Corporation), paragraphs [0021] to [0061]. Baker discloses composition and methods of preparation of a variety of star polymers.

[0026] In one embodiment the star polymer may be a polymer derived from greater than 50 wt % or more of a non-diene monomer.

[0027] In different embodiments the star polymer may contain greater than 50 wt %, or 55 wt % or more, or 70 wt % or more, or 90 wt % or more, or 95 wt % or more, or 100 wt % of a non-diene monomer (that is to say, non-diene monomer units or units derived from polymerisation of one of more non-diene monomers). Examples of diene monomers include 1,3-butadiene or isoprene. In contrast, examples of a non- diene of the present invention may include styrene, methacrylates, acrylates, or mixtures thereof. In one embodiment the star polymer may be a polymer derived from methacrylates, or mixtures thereof. [0028] As described hereinafter the molecular weight of the viscosity modifier has been determined using known methods, such as GPC analysis using polystyrene standards. Methods for determining molecular weights of polymers are well known. The methods are described for instance: (i) P.J. Flory, "Principles of star polymer Chemistry", Cornell University Press 91953), Chapter VII, pp 266-315; or (ii) "Macromolecules, an Introduction to star polymer Science", F. A. Bovey and F. H. Winslow, Editors, Academic Press (1979), pp 296-312. As used herein the weight average and number average molecular weights of the polymers of the invention are obtained by integrating the area under the peak corresponding to the star polymer of the invention, which is normally the major high molecular weight peak, excluding peaks associated with diluents, impurities, uncoupled star polymer chains and other additives.

[0029] The star polymer may have a weight average molecular weight of 100,000 to 1,000,000, or 125,000 to 700,000, or 150,000 to 500,000, or 200,000 to 400,000. The weight average molecular weight of an arm of the star polymer may be in the range of 8,000 to 150,000, or 10,000 to 100,000 or 15,000 to 75,000, or 25,000 to 70,000.

[0030] As used herein the shear stability index (SSI) of the star polymer may be determined by a 20 hour K L test (Volkswagen Tapered Bearing Roller Test). The test procedure is set out in both CEC-L-45-A-99 or equivalent test method DIN

[0031] The star polymer SSI may be in the range of 0 to 100, or 0 to 80, or 0 to 60, or 0 to 50, 0 to 20, or 0 to 15, or 0 to 10, or 0 to 5. An example of a suitable range for the SSI includes 1 to 5, or 25 to 65.

[0032] The star polymer may be a homopolymer or a copolymer, that is, its arms may be homopolymeric or copolymeric. In one embodiment the star polymer may be a copolymer. The star polymer may be a star polymer having a random, tapered, di-block, tri-block or multi-block architecture. Typically the star polymer has random or tapered architecture.

[0033] The star polymer may have arms that may have a block-arm architecture, or hetero-arm architecture, or tapered-arm architecture. Tapered- arm architecture has a variable composition across the length of a star polymer arm. For example, the tapered arm may be composed of, at one end, a relatively pure first monomer and, at the other end, a relatively pure second monomer. The middle of the arm is more of a gradient composition of the two monomers.

[0034] The star polymer derived from a block-arm typically contains one or more star polymer arms derived from two or more monomers in block structure within the same arm. A more detailed description of the block-arm is given in Chapter 13 (pp. 333-368) of "Anionic Polymerization, Principles and Practical Applications" by Henry Hsieh and Roderic Quirk (Marcel Dekker, Inc, New York, 1996) (hereinafter referred to as Hsieh et al.).

[0035] The star polymer typically has architecture such that the arms may be chemically bonded to a core portion. The core portion may be a polyvalent (meth) acrylic monomer, oligomer, polymer, or copolymer thereof, or a polyvalent divinyl non-acrylic monomer, oligomer polymer, or copolymer thereof. In one embodiment the polyvalent divinyl non-acrylic monomer may be divinyl benzene. In one embodiment the polyvalent (meth)acrylic monomer may be an acrylate or methacrylate ester of a polyol or a methacrylamide of a polyamine, such as an amide of a polyamine, for instance a methacrylamide or an acrylamide. In different embodiments the polyvalent (meth)acrylic monomer may be (i) a condensation reaction product of an acrylic or methacrylic acid with a polyol or (ii) a condensation reaction product of an acrylic or methacrylic acid with a polyamine.

[0036] The polyol which may be condensed with the acrylic or methacrylic acid in one embodiment contains 2 to 20 carbon atoms, in another embodiment 3 to 15 carbon atoms and in another embodiment 4 to 12 carbon atoms; and the number of hydroxyl groups present in one embodiment may be 2 to 10, in another embodiment 2 to 4 and in another embodiment 2. Examples of polyols include ethylene glycol, poly (ethylene glycols), alkane diols such as 1 ,6-hexane diol or triols such as trimethylolpropane, oligomerised trimethylolpropanes such as Boltorn® materials sold by Perstorp Polyols. Examples of polyamines include polyalkylenepolyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and mixtures thereof.

[0037] Examples of the polyvalent unsaturated (meth)acrylic monomer include ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, glycerol diacrylate, glycerol triacrylate, mannitol hexaacrylate, 4-cyclohexanediol diacrylate, 1 ,4-benzenediol dimethacrylate, pentaerythritol tetraacrylate, 1 ,3 -propanediol diacrylate, 1 ,5- pentanediol dimethacrylate, bis-acrylates and methacrylates of polyethylene glycols of molecular weight 200-4000, polycaprolactonediol diacrylate, pentaerythritol triacrylate, 1 , 1 , 1 -trimethylolpropane triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, 1 ,1 ,1 -trimethylolpropane trim ethacryl ate, hexamethylenediol diacrylate or hexamethylenediol dimethacrylate or an alkylene bis-(meth)acrylamide.

[0038] The star polymer with branched, comb-like, radial or star architecture may have 2 or more arms, or 5 or more arms, or 7 or more arms, or 10 or more arms, for instance 12 to 100, or 14 to 50, or 16 to 40 arms. The star polymer with branched, comb-like, radial or star architecture may have 120 arms or less, or 80 arms or less, or 60 arms or less.

[0039] The star polymer may be obtained/obtainable from a controlled radical polymerisation technique. Examples of a controlled radical polymerisation technique include RAFT, ATRP or nitroxide mediated processes. The star polymer may also be obtained/obtainable from anionic polymerisation processes. In one embodiment the star polymer may be obtained/obtainable from RAFT, ATRP or anionic polymerisation process. In one embodiment the star polymer may be obtained/obtainable from RAFT or ATRP polymerisation process. In one embodiment the star polymer may be obtained/obtainable from a RAFT polymerisation process.

[0040] Methods of preparing polymers using ATRP, RAFT or nitroxide- mediated techniques are disclosed in the example section of International Publication WO 2006/047398, see examples 1 to 47. [0041] More detailed descriptions of polymerisation mechanisms and related chemistry is discussed for nitroxide -mediated polymerisation (Chapter 10, pages 463 to 522), ATRP (Chapter 1 1 , pages 523 to 628) and RAFT (Chapter 12, pages 629 to 690) in the Handbook of Radical Polymerization, edited by Krzysztof Matyjaszewski and Thomas P. Davis, 2002, published by John Wiley and Sons Inc (hereinafter referred to as "Matyjaszewski et al.").

[0042] The discussion of the star polymer mechanism of ATRP polymerisation is shown on page 524 in reaction scheme 1 1.1 , page 566 reaction scheme 1 1.4, reaction scheme 1 1 ,7 on page 571 , reaction scheme 1 1.8 on page 572 and reaction scheme 1 1.9 on page 575 of Matyjaszewski et al. In ATRP polymerisation, groups that may be transferred by a radical mechanism include halogens (from a halogen-containing compound) or various ligands. A more detailed review of groups that may be transferred is described in US 6,391 ,996, or paragraphs 61 to 65 of International Publication WO 2006/047398.

[0043] In RAFT polymerisation, chain transfer agents are important. A more detailed review of suitable chain transfer agents is found in paragraphs [0066] to [0071] of International Publication WO 2006/047398. In one embodiment a suitable RAFT chain transfer agent includes 2-dodecylsulphanylthiocarbonyl- sulphanyl-2-methyl -propionic acid butyl ester, cumyl dithiobenzoate or mixtures thereof. A discussion of the star polymer mechanism of RAFT polymerisation is shown on page 664 to 665 in section 12.4.4 of Matyjaszewski et al.

[0044] When the star polymer is prepared from anionic polymerisation techniques, initiators include, for example, hydrocarbyl lithium initiators such as alkyl lithium compounds (e.g., methyl lithium, n-butyl lithium, sec-butyl lithium), cycloalkyl lithium compounds (e.g., cyclohexyl lithium and aryl lithium compounds (e.g., phenyl lithium, 1-methylstyryl lithium, p-tolyl lithium, naphyl lithium and l , l -diphenyl-3-methylpentyl lithium. Also, useful initiators include naphthalene sodium, l ,4-disodio-l , l ,4,4-tetraphenylbutane, diphenylmethyl potassium or diphenylmethyl sodium.

[0045] A more detailed description of process to prepare the star polymer derived from anionic processes is discussed in International Patent Application WO 96/23012, page 3, line 1 1 to page 5, line 8. Page 7, line 25 to page 10, line 15 of WO 96/23012 further describes methods of preparing polymers by anionic polymerisation techniques. A detailed description of anionic polymerisation process is given in Textbook of Star Polymer Science, edited by Fred W. Billmeyer Jr., Third Edition, 1984, Chapter 4, pages 88-90.

[0046] The star polymer may comprise at least one of (a) a star polymer derived from monomers comprising: (i) a vinyl aromatic monomer; and (ii) a carboxylic monomer (typically maleic anhydride, maleic acid, (meth)acrylic acid, itaconic anhydride or itaconic acid) or derivatives thereof; (b) a poly(meth)acrylate; (c) a functionalised polyolefin; (d) an ethylene vinyl acetate copolymer; (e) a fumarate copolymer; (f) a copolymer derived from (i) an a- olefin and (ii) a carboxylic monomer (typically maleic anhydride, maleic acid, (meth)acrylic acid, itaconic anhydride or itaconic acid) or derivatives thereof; or (g) mixtures thereof. In one embodiment the star polymer with pendant groups comprises a polymethacrylate or mixtures thereof.

[0047] In one embodiment the star polymer may be a poly(meth)acrylate (typically a polymethacrylate). The star polymer may be derived from a monomer composition comprising:

(a) 50 wt % to 100 wt % (or 65 wt % to 95 wt %) of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 10 to 30, or 10 to 20, or 12 to 18, or 12 to 15 carbon atoms, or mixtures thereof;

(b) 0 wt % to 40 wt % (or 5 wt % to 30 wt %) of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 1 to 9, or 1 to 4 carbon atoms (for example methyl, butyl, or 2-ethylhexyl) , or mixtures thereof; and

(c) 0 wt % to 10 wt % (or 0 wt % to 5 wt %, or 0.1 to 2 wt %) of a nitrogen-containing monomer.

[0048] In one embodiment the star polymer may be a poly(meth)acrylate (typically a polymethacrylate), the star polymer may be derived from a monomer composition comprising: (a) 65 wt % to 95 wt % (or 65 wt % to 94.9 wt %) of an alkyl (meth) aery late, wherein the alkyl group of the (meth)acrylate has 10 to 30, or 10 to 20, or 12 to 18, or 12 to 15 carbon atoms, or mixtures thereof;

(b) 5 wt % to 30 wt % of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 1 to 9, or 1 to 4 carbon atoms (for example methyl, butyl, or 2-ethylhexyl) , or mixtures thereof; and

(c) 0 wt % to 5 wt % (or 0.1 to 2 wt %) of a nitrogen-containing monomer.

[0049] The alkyl (meth)acrylate includes, for example, compounds derived from saturated alcohols, such as methyl (meth)acrylate, butyl (meth)acrylate, 2-methylpentyl (meth)acrylate, 2-propylheptyl (meth)acrylate, 2-butyloctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (methacrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, 2-tert-butylheptyl (meth)acrylate, 3-isopropylheptyl (meth) acryl ate, decyl (meth)acrylate, undecyl (meth)acrylate, 5-methylundecyl (meth)acrylate, dodecyl (meth)acrylate, 2-methyldodecyl (meth)acrylate, tridecyl (meth)acrylate, 5-methyltridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, 2-methylhexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, cetyleicosyl (meth)acrylate, stearyleicosyl (meth)acrylate, docosyl (meth)acrylate and/or eicosyltetratriacontyl (meth)acrylate; (meth) acryl ates derived from unsaturated alcohols, such as oleyl (meth)acrylate; and cycloalkyl (meth)acrylates, such as 3-vinyl-2-butylcyclohexyl (meth)acrylate or bornyl (meth)acrylate.

[0050] The alkyl (meth)acrylates with long-chain alcohol-derived groups may be obtained, for example, by reaction of a (meth)acrylic acid (by direct esterification) or methyl methacrylate (by transesterification) with long -chain fatty alcohols, in which reaction a mixture of esters such as (meth)acrylate with alkyl groups of various chain lengths is generally obtained. These fatty alcohols include Oxo Alcohol® 791 1 , Oxo Alcohol® 7900 and Oxo Alcohol® 1 100 of Monsanto; Alphanol® 79 of ICI; Nafol® 1620, Alfol® 610 and Alfol® 810 of Condea (now Sasol); Epal® 610 and Epal® 810 of Ethyl Corporation; Linevol® 79, Linevol® 91 1 and Dobanol® 25 L of Shell AG; Lial® 125 of Condea Augusta, Milan; Dehydad® and Lorol® of Henkel KGaA (now Cognis) as well as Linopol® 7-1 1 and Acropol® 91 of Ugine Kuhlmann.

[0051] In one embodiment the star polymer may be further functionalised in the core or the polymeric arms with a nitrogen-containing monomer. The nitrogen-containing monomer may be referred to as a dispersant monomer. The nitrogen-containing monomer may include a vinyl-substituted nitrogen heterocyclic monomer, a dialkylaminoalkyl (meth)acrylate monomer, a dialkylaminoalkyl (meth)acryl amide monomer, a tertiary-(meth)acrylamide monomer or mixtures thereof.

[0052] In one embodiment the core or polymeric arms further comprise a (meth)acrylamide or a nitrogen containing (meth)acrylate monomer. Examples of a suitable nitrogen-containing vinyl monomer include Ν,Ν-dimethylacrylamide, N-vinyl carbonamides such as N-vinyl-formamide, vinyl pyridine, N-vinylacetoamide, N-vinyl-n-propionamides, N-vinyl hydroxyacetoamide, N-vinyl imidazole, N-vinyl pyrrolidinone, N-vinyl caprolactam, dimethyl amino ethyl acrylate (DMAEA), dimethylaminoethyl- methacrylate (DMAEMA), dimethyl aminobutylacryl amide, dimethylamino- propylmethacrylate (DMAPMA), dimethylamine-propyl-acrylamide, dimethyl- aminopropylmethacrylamide, dimethylaminoethyl-acrylamide, or mixtures thereof.

[0053] A dispersant monomer may also be oxygen-containing compound. The oxygen-containing compound may include hydroxyalkyl (meth)acrylates such as 3-hydroxypropyl (meth)acrylate, 3,4-dihydroxybutyl (meth)acrylate, 2- hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2, 5 -dimethyl- 1 ,6- hexanediol (meth)acrylate, 1 , 10-decanediol (meth)acrylate, carbonyl-containing (meth)acrylates such as 2-carboxyethyl (meth)acrylate, carboxymethyl (meth) acrylate, oxazolidinylethyl (meth)acrylate, N-(methacryloyl- oxy)formamide, acetonyl (meth)acrylate, N-methacryloylmorpholine, N- methacryloyl-2-pyrrolidinone, N-(2-methacryloyloxyethyl)-2-pyrrolidinone, N- (3-methacryloyloxypropyl)-2-pyrrolidinone, N-(2-methacryloyloxypentadecyl)- 2-pyrrolidinone, N-(3-methacryloyloxyheptadecyl)-2-pyrrolidinone; glycol di(meth)acrylates such as 1 ,4-butanediol (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-ethoxyethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth) aery late, or mixtures thereof.

[0054] Other examples of suitable non-carbonyl oxygen containing compounds capable of being incorporated into the copolymer include (meth)acrylates of ether alcohols, such as tetrahydro fur fury 1 (meth)acrylate, vinyloxyethoxyethyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, 1 - butoxypropyl (meth)acrylate, l -methyl-(2-vinyloxy)ethyl (meth)acrylate, cyclo- hexyloxym ethyl (meth)acrylate, methoxymethoxyethyl (meth) aery late, benzyloxymethyl (meth)acrylate, furfuryl (meth)acrylate, 2-butoxyethyl (meth) aery late, 2-ethoxyethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth) aery late, allyloxymethyl (meth)acrylate, 1 -ethoxybutyl (meth)acrylate, methoxymethyl (meth)acrylate, 1 -ethoxyethyl (meth)acrylate, ethoxymethyl (meth) aery late and ethoxylated (meth)acrylates which typically have 1 to 20, or 2 to 8, ethoxy groups, or mixtures thereof.

Substantially Linear Polymer

[0055] The composition of the invention includes a substantially linear polymer with a weight average molecular weight of 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 12,000 to 20,000.

[0056] The substantially linear polymer may be a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol. In one embodiment, the substantially linear polymer may be a copolymer comprising units derived from monomers (i) one or more alpha olefins and (ii) one or more alkyl (meth)acrylate esters. The ethylenically unsaturated carboxylic acid may be esterified with alcohol before or after polymerisation with the a-olefin. In one embodiment the ethylenically unsaturated carboxylic acid may be esterified with alcohol before polymerisation with the a-olefin. In one embodiment the ethylenically unsaturated carboxylic acid may be esterified with alcohol after polymerisation with the a-olefin. [0057] A commercially available copolymer prepared by esterification before polymerisation is available from Akzo Nobel sold under the tradename Ketjenlube®3700. The alcohol may have 1 to 40, or 1 to 30, or 4 to 20, or 6 to 16 carbon atoms. Examples of a suitable alcohol include 2-ethylhexanol, 2- butyloctanol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, eicosanol, or mixtures thereof. A copolymer of this type is described in more detail in US Patents 4,526,950, or 6,419,714, or 6,573,224, or 6,174,843.

[0058] The ethylenically unsaturated carboxylic acid may be esterified with alcohol after polymerisation with the α-olefm. A copolymer of this type may be a substantially linear polymer that may in one embodiment be (a) a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer typically has a reduced specific viscosity of up to 0.2, (b) a poly(meth)acrylate, or mixtures thereof.

[0059] The substantially linear polymer may be present in the compositions described herein at 0.1 wt % to 50 wt %, or 2 wt % to 40 wt %, or 5 wt % to 30 wt %, or 8 wt % to 20 wt % of the lubricating composition. In certain embodiments the lubricating composition contains 0.3 to 15 wt % of star polymer and 1 to 35 wt % of substantially linear polymer. In other embodiments, the lubricating composition contains 0.45 to 5 wt % of star polymer and 2 to 25 wt % of substantially linear polymer.

Linear Poly(meth)acrylate

[0060] In one embodiment the substantially linear polymer includes a poly(meth)acrylate, or mixtures thereof.

[0061] In one embodiment the substantially linear polymer includes a poly(meth)acrylate (typically a polymethacrylate) with units derived from a mixture of alkyl (meth)acrylate ester monomers containing, (a) 8 to 24, or 12 to 18, or to 15 carbon atoms in the alcohol-derived portion of the ester group and (b) 6 to 1 1 , or 8 to 1 1 , or 8 carbon atoms in the alcohol-derived portion of the ester group, and which have 2-(C_1-4 alkyl)-substituents, and optionally, at least one monomer selected from the group consisting of (meth)acrylic acid esters containing 1 to 7 carbon atoms in the alcohol-derived portion of the ester group and which are different from (meth)acrylic acid esters (a) and (b), vinyl aromatic compounds (or vinyl aromatic monomers); and nitrogen-containing vinyl monomers such as those disclosed above; provided that no more than 60% by weight, or no more than 50% by weight, or no more than 35% by weight of the esters contain not more than 10 carbon atoms in the alcohol-derived portion of the ester group. The linear polymer of this type is described in more detail in US 6,124,249, or EP 0 937 769 Al paragraphs [0019] and [0031] to [0067]. (The "alcohol-derived portion" refers to the "-OR" portion of an ester, when written as R'C(=0)-OR, whether or not it is actually prepared by reaction with an alcohol.) Optionally, the linear polymer may further contain a third monomer. The third monomer may be styrene, or mixtures thereof. The third monomer may be present in an amount 0% to 25% of the polymer composition, or from 1% to 15% of the composition, 2% to 10% of the composition, or even from 1% to 3% of the composition.

[0062] Typically, the mole ratio of esters (a) to esters (b) in the copolymer ranges from 95 :5 to 35 :65, or 90: 10 to 60:40, or 80:20 to 50:50.

[0063] The esters are usually aliphatic esters, typically alkyl esters. In one embodiment the ester of (a) may be a C 12-15 alkyl methacrylate and the ester of (b) may be 2-ethylhexyl methacrylate.

[0064] In one embodiment, the ester groups in ester (a) contain branched alkyl groups. The ester groups may contain 2 to 65%, or 5 to 60%> of the ester groups having branched alkyl groups.

[0065] The Ci_₄ alkyl substituents may be methyl, ethyl, and any isomers of propyl and butyl.

[0066] The weight average molecular weight of the poly(meth)acrylate may be 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 12,000 to 20,000. Copolymer of (i) g-Olefin and (ii) an Ethylenically Unsaturated Carboxylic Acid or Derivatives Thereof

[0067] In one embodiment the substantially linear polymer includes a copolymer comprising units derived from monomers (i) an α-olefm and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer typically has a reduced specific viscosity of up to 0.2, or up to 0.15, or up to 0.10, or up to 0.08. In one embodiment the reduced specific viscosity may be up to 0.08 (or 0.02 to 0.08 (or 0.02 to 0.07, 0.03 to 0.07 or 0.04 to 0.06) .

[0068] A measurement correlating with molecular weight of the copolymer (or interpolymer such as an alternating copolymer) may be expressed in terms of the "reduced specific viscosity" of the copolymer which is a recognised means of expressing the molecular size of a polymeric substance. As used herein, the reduced specific viscosity (abbreviated as RSV) is the value typically obtained in accordance with the formula RSV = (Relative Viscosity - l)/Concentration, wherein the relative viscosity is determined by measuring, by means of a dilution viscometer, the viscosity of a solution of 1 .6 g of the polymer in 100 cm of acetone and the viscosity of acetone at 30 °C. For purpose of computation by the above formula, the concentration is adjusted to 1.6 g of the copolymer per 100 cm of acetone. A more detailed discussion of the reduced specific viscosity, also known as the specific viscosity, as well as its relationship to the average molecular weight of a copolymer, appears in Paul J. Flory, Principles of Polymer Chemistry, (1953 Edition) pages 308 et seq.

[0069] In one embodiment the copolymer may be derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof,

wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a primary alcohol branched at the β- or higher position,

wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol (e.g, a secondary alcohol), wherein 0.01 to 10 % of the carboxylic acid units has at least one of an amino-, amido- and/or imido- group, and

wherein the copolymer has a reduced specific viscosity (prior to esterification) of up to 0.08.

[0070] In one embodiment the copolymer may be derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof,

wherein 0.1 to 99.9 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol,

wherein 0 to 10 % of the carboxylic acid units has at least one of an amino-, amido- and/or imido- group, and

wherein the copolymer has a reduced specific viscosity of up to 0.08.

[0071] A linear alcohol may include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, or mixtures thereof. In one embodiment the linear alcohol contains 6 to 30, or 8 to 20, or 8 to 15 carbon atoms (typically 8 to 15 carbon atoms).

[0072] The linear alcohol may include commercially available materials such as Oxo Alcohol® 791 1 , Oxo Alcohol® 7900 and Oxo Alcohol® 1 100 of Monsanto; Alphanol® 79 of ICI; Nafol® 1620, Alfol® 610 and Alfol® 810 of Condea (now Sasol); Epal® 610 and Epal® 810 of Ethyl Corporation (now Afton); Linevol® 79, Linevol® 91 1 and Dobanol® 25 L of Shell AG; Lial® 125 of Condea Augusta, Milan; Dehydad® and Lorol® of Henkel KGaA (now Cognis) as well as Linopol® 7-1 1 and Acropol® 91 of Ugine Kuhlmann.

[0073] In one embodiment the copolymer may be derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof, wherein 5 to 15 percent of the carboxylic acid units are esterified with a primary alcohol branched at the β- or higher position,

wherein 0.1 to 95 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol,

wherein 0 to less than 2 % of the carboxylic acid units has at least one of an amino-, amido- and/or imido- group, and

wherein the copolymer has a reduced specific viscosity of up to 0.08.

[0074] In one embodiment the copolymer comprises units derived from monomers (i) an α-olefm and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position. In certain embodiments the copolymer may be represented by the formula below. Ester or other groups with the primary alcohol-derived moiety branched at the β- or higher position may be represented within the ( )_w shown in the formula:

Formula (I)

wherein

Formula (I) may comprise a copolymer backbone (BB), and one or more pendant groups as shown, wherein BB may be derived from a copolymer of (i) an a-olefm and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof (typically fumaric acid, maleic anhydride, maleic acid, (meth)acrylic acid, itaconic anhydride or itaconic acid);

X may be a functional group which either (i) contains a carbon and at least one oxygen or nitrogen atom (such as an ester or amide, or imide linkage), or (ii) is an alkylene group with 1 to 5 carbon atoms (typically -CH₂-), connecting the copolymer backbone and a branched hydrocarbyl group contained within ( )_y, (typically X may be X may be a functional group which either (i) contains a carbon and at least one oxygen or nitrogen atom);

w may be the number of pendant groups attached to the copolymer backbone, which may be in the range of 2 to 2000, or 2 to 500, or 5 to 250; y may be 0, 1 , 2 or 3, provided that in at least 1 mol % of the pendant groups, y is not zero; and with the proviso that when y is 0, X is bonded to a terminal group in a manner sufficient to satisfy the valence of X, wherein the terminal group is selected from hydrogen, alkyl, aryl, a metal (typically introduced during neutralisation of ester reactions. Suitable metals include calcium, magnesium, barium, zinc, sodium, potassium or lithium) or ammonium cation, and mixtures thereof;

p may be an integer in the range of 1 to 15 (or 1 to 8, or 1 to 4); and

R' and R" may independently be linear or branched hydrocarbyl groups, and the combined total number of carbon atoms present in R' and R" may be at least 12 (or at least 16, or at least 18 or at least 20).

[0075] In different embodiments the copolymer with pendant groups may contain 0.10 % to 100 %, or 0.5 % to 20 %, or 0.75 % to 10 %, branched hydrocarbyl groups represented by a group within ( )_y of the formula above, expressed as a percentage of the total number of pendant groups . (The pendant groups of formula (1) may also be used to define the ester groups as defined above by the phrase "esterified with a primary alcohol branched at the β- or higher position").

[0076] In different embodiments the functional groups defined by X on the formula above, may comprise at least one of -C0₂-, -C(0)N= or -(CH₂)_V-, wherein v is an integer in the range of 1 to 20, or 1 to 10, or 1 to 2.

[0077] In one embodiment X may be derived from an ethylenically unsaturated carboxylic acid or derivatives thereof. Examples of a suitable carboxylic acid or derivatives thereof typically include maleic anhydride, maleic acid, (meth)acrylic acid, itaconic anhydride or itaconic acid. In one embodiment the ethylenically unsaturated carboxylic acid or derivatives thereof may be at least one of maleic anhydride or maleic acid.

[0078] In one embodiment X is other than an alkylene group, connecting the copolymer backbone and the branched hydrocarbyl groups.

[0079] In different embodiments the pendant groups may be esterified, amidated or imidated functional groups.

[0080] In one embodiment the pendant groups may be derived from esterified and/or amidated functional groups.

[0081] In one embodiment the copolymer includes esterified pendant groups.

The pendant groups may be derived from Guerbet alcohols. The Guerbet alcohols may contain 10 to 60, or 12 to 60, or 16 to 40 carbon atoms. In one embodiment the primary alcohol branched at the β- or higher position described herein may be a Guerbet alcohol. Methods to prepare Guerbet alcohols are disclosed in US Patent 4,767,815 (see column 5, line 39 to column 6, line 32).

[0082] Examples of suitable groups for R' and R" on the formula defined above include the following:

1) alkyl groups containing Ci₅_i6 polymethylene groups, such as 2-C_1-15 alkyl-hexadecyl groups (e.g. 2-octylhexadecyl) and 2-alkyl-octadecyl groups

(e.g. 2-ethyloctadecyl, 2-tetradecyl-octadecyl and 2-hexadecyloctadecyl);

2) alkyl groups containing C i3_i₄ polymethylene groups, such as 1 -C_1-15 alkyl-tetradecyl groups (e.g. 2-hexyltetradecyl, 2-decyltetradecyl and 2-undecyltridecyl) and 2-C_1-15 alkyl-hexadecyl groups (e.g. 2-ethyl-hexadecyl and 2-dodecylhexadecyl);

3) alkyl groups containing Cio_i₂polym ethylene groups, such as 2-C_1-15 alkyl-dodecyl groups (e.g. 2-octyldodecyl) and 2-C_1-15 alkyl-dodecyl groups (2-hexyldodecyl and 2-octyldodecyl), 2-C_1-15 alkyl-tetradecyl groups (e.g. 2-hexyltetradecyl and 2-decyltetradecyl); 4) alkyl groups containing C6-₉polymethylene groups, such as 2-C_1-15 alkyl-decyl groups (e.g. 2-octyldecyl) and 2,4-di-C_1-15 alkyl-decyl groups (e.g. 2- ethyl-4-butyl-decyl group);

5) alkyl groups containing Ci_₅ polymethylene groups, such as 2-(3- methylhexyl)-7-methyl-decyl and 2-(l ,4-dimethylbutyl)-5,7,7-trimethyl-octyl groups; and

6) and mixtures of two or more branched alkyl groups, such as alkyl residues of oxoalcohols corresponding to propylene oligomers (from hexamer to undecamer), ethylene/propylene (molar ratio 16 : 1 -1 : 1 1) oligomers, iso-butene oligomers (from pentamer to octamer), C_5-17 α-olefm oligomers (from dimer to hexamer).

[0083] The pendant groups may contain a total combined number of carbon atoms on R' and R" in the range of 12 to 60, or 14 to 50, or 16 to 40, or 18 to 40, or 20 to 36.

[0084] Each of R' and R" may individually contain 5 to 25, or 8 to 32, or 10 to 18 methylene carbon atoms. In one embodiment the number of carbon atoms on each R' and R" group may be 10 to 24.

[0085] Examples of suitable primary alcohol branched at the β- or higher position include 2-ethylhexanol, 2-propyl heptanol, 2-butyloctanol, 2- hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, or mixtures thereof.

[0086] The ethylenically unsaturated carboxylic acid or derivatives thereof may be an acid or anhydride or derivatives thereof that may be wholly esterified, partially esterified or mixtures thereof. When partially esterified, other functional groups include acids, salts or mixtures thereof. Suitable salts include alkali metals, alkaline earth metals or mixtures thereof. The salts include lithium, sodium, potassium, magnesium, calcium or mixtures thereof. The unsaturated carboxylic acid or derivatives thereof includes acrylic acid, methyl acrylate, methacrylic acid, maleic acid or anhydride, fumaric acid, itaconic acid or anhydride or mixtures thereof, or substituted equivalents thereof. [0087] Suitable examples of the ethylenically unsaturated carboxylic acid or derivatives thereof include itaconic anhydride, maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, dimethyl maleic anhydride or mixtures thereof.

[0088] In one embodiment the ethylenically unsaturated carboxylic acid or derivatives thereof includes maleic anhydride or derivatives thereof.

[0089] Examples of an alpha-olefm include 1 -decene, 1-undecene, 1 -dodecene, 1 -tridecene, 1-tetradecene, 1 -pentadecene, 1 -hexadecene, 1 -hepta- decene 1 -octadecene, or mixtures thereof. An example of a useful alpha-olefm is 1 -dodecene. The alpha-olefm may be a branched alpha-olefin, or mixtures thereof. If the a-olefm is branched, the number of carbon atoms of the a-olefin may range from 4 to 32, or 6 to 20, or 8 to 16.

[0090] In one embodiment the copolymer of the invention further includes a nitrogen containing group such as those disclosed above. The nitrogen containing group may be derived from a nitrogen containing compound capable of being incorporated during copolymerization. In one embodiment the copolymer of the invention further includes a nitrogen containing group that may be capable of reacting with the functionalised copolymer backbone, typically for capping the copolymer backbone. The capping may result in the copolymer having ester, amide, imide or amine groups. The nitrogen group is described in more detail in paragraphs [0069] to [0087] of PCT Patent Application Number PCT/US09/052028, filed on July 29, 2009 by Price, Barton, Visger, entitled "Novel Copolymers and Lubricating Compositions Thereof .

[0091] In one embodiment the copolymer comprises units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof may be further reacted with an amine to additionally provide oxidation control. Typically, the copolymer with oxidation control contains an incorporated residue of an amine-containing compound such as morpholines, pyrrolidinones, imidazolidinones, acetamides, β-alanine alkyl esters, or mixtures thereof. Examples of suitable nitrogen-containing compounds include 3- morpholin-4-yl-propylamine, 3-morpholin-4-yl-ethylamine, β-alanine alkyl esters (typically alkyl esters have 1 to 30, or 6 to 20 carbon atoms), or mixtures thereof. [0092] In one embodiment the compounds based on imidazolidinones, cyclic carbamates or pyrrolidinones may be derived from a compound of general structure:

wherein

X = -OH or NH₂;

Hy" may be hydrogen, or a hydrocarbyl group (typically alkyl, or C_1-4-, or C₂- alkyl);

Hy may be a hydrocarbylene group (typically alkyl ene, or C_1-4-, or C₂- alkylene); Q = >NH, >NR, >CH₂, >CHR, >CR₂, or -O- (typically >NH, or >NR) and

R may be Ci_₄ alkyl.

[0093] In one embodiment the imidazolidinone includes l-(2-amino-ethyl)- imidazolidin-2-one (may also be called aminoethylethyleneurea), l-(3-amino- propyl)-imidazolidin-2-one, l-(2-hydroxy-ethyl)-imidazolidin-2-one, l-(3-amino- propyl)-pyrrolidin-2-one, l -(3-amino-ethyl)-pyrrolidin-2-one, or mixtures thereof.

[0094] In one embodiment the copolymer may be reacted with an amine - containing compound selected from morpholines, imidazolidinones, and mixtures thereof.

Oils of Lubricating Viscosity

[0095] The lubricating composition comprises an oil of lubricating viscosity. Such oils include natural and synthetic oils, oil derived from hydro cracking, hydrogenation, and hydro finishing, unrefined, refined, re -refined oils or mixtures thereof. A more detailed description of unrefined, refined and re -refined oils is provided in International Publication WO2008/147704, paragraphs [0054] to [0056] (a similar disclosure is provided in US Patent Application 2010/197536, see [0072] to [0073]). A more detailed description of natural and synthetic lubricating oils is described in paragraphs [0058] to [0059] respectively of WO2008/147704 (a similar disclosure is provided in US Patent Application 2010/197536, see [0075] to [0076]). Synthetic oils may also be produced by Fischer-Tropsch reactions and typically may be hydroisomerised Fischer-Tropsch hydrocarbons or waxes. In one embodiment oils may be prepared by a Fischer- Tropsch gas-to-liquid synthetic procedure as well as other gas -to-liquid oils.

[0096] Oils of lubricating viscosity may also be defined as specified in April 2008 version of "Appendix E - API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils", section 1.3 Sub -heading 1.3. "Base Stock Categories". In one embodiment the oil of lubricating viscosity may be an API Group II or Group III oil. In one embodiment the oil of lubricating viscosity may be an API Group III base oil (typically including hydrocracked/hydroisomerized base oil).

[0097] The amount of the oil of lubricating viscosity present is typically the balance remaining after subtracting from 100 wt % the sum of the amount of the compound of the invention and the other performance additives .

[0098] The lubricating composition may be in the form of a concentrate and/or a fully formulated lubricant. If the lubricating composition of the invention (comprising the additives disclosed herein) is in the form of a concentrate which may be combined with additional oil to form, in whole or in part, a finished lubricant), the ratio of the of these additives to the oil of lubricating viscosity and/or to diluent oil include the ranges of 1 :99 to 99: 1 by weight, or 80:20 to 10:90 by weight.

Other Performance Additives

[0099] Compositions derived from the copolymer and/or lubricating compositions described herein optionally further includes other performance additives. The other performance additives comprise at least one of metal deactivators, detergents, dispersants, viscosity modifiers, friction modifiers, corrosion inhibitors, dispersant viscosity modifiers, antiwear agents, extreme pressure agents, antiscuffmg agents, antioxidants, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents and mixtures thereof. Typically, fully-formulated lubricating oil will contain one or more of these performance additives.

Dispersants

[0100] Dispersants are known and include for example an N-substituted long chain alkenyl succinimide, a Mannich base, or mixtures thereof. Examples of N- substituted long chain alkenyl succinimides include polyisobutylene succinimide, wherein the polyisobutylene from which it is derived has a number average molecular weight in the range 350 to 5000, or 500 to 3000, or 750 to 1 150.

[0101] The dispersants may also be post-treated by conventional methods by a reaction with any of a variety of agents. Among these are boron compounds (such as boric acid), urea, thiourea, dimercaptothiadiazoles, carbon disulphide, aldehydes, ketones, carboxylic acids such as terephthalic acid, hydrocarbon- substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, and phosphorus compounds. In one embodiment the post-treated dispersant is borated. In one embodiment the post-treated dispersant is reacted with dimercaptothiadiazoles.

Detergents

[0102] Detergents are known and include neutral or overbased detergents, i.e., ones prepared by conventional processes known in the art. Suitable detergent substrates include, phenates, sulphur containing phenates, sulphonates, salixarates, salicylates, carboxylic acid, phosphorus acid, alkyl phenol, sulphur coupled alkyl phenol compounds, or saligenins. In one embodiment the detergent includes a magnesium or calcium sulphonate, or mixtures thereof.

Antioxidant

[0103] Antioxidant compounds are known and include sulphurised olefins, diphenylamines (such as dinonyl diphenyl amine), hindered phenols, molybdenum dithiocarbamates, and mixtures thereof. Antioxidant compounds may be used alone or in combination.

[0104] The hindered phenol antioxidant often contains a secondary butyl and/or a tertiary butyl group as a sterically hindering group. The phenol group is often further substituted with a hydrocarbyl group and/or a bridging group linking to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4- ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol or 4-butyl-2,6-di- tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol. In one embodiment the hindered phenol antioxidant may be an ester and may include, e.g., Irganox™ L- 135 from Ciba. Suitable examples of molybdenum dithiocarbamates which may be used as an antioxidant include commercial materials sold under the trade names such as Vanlube 822™ and Molyvan™ A from R. T. Vanderbilt Co., Ltd., and Adeka Sakura-Lube™ S-100, S-165 and S-600 from Asahi Denka Kogyo K. K and mixtures thereof.

Viscosity Modifiers

[0105] In addition to the polymers described herein as part of the invention the lubricating composition may optionally further contain other known viscosity modifiers. The viscosity modifiers may be hydrogenated styrene -butadiene rubbers, ethylene -propylene copolymers, hydrogenated styrene -isoprene polymers, hydrogenated diene polymers, polyalkyl styrenes, polyolefins, esters of maleic anhydride-styrene copolymers, or mixtures thereof.

Antiwear Agent

[0106] The lubricating composition optionally further includes at least one antiwear agent. Examples of suitable antiwear agents include oil soluble amine salts of phosphorus compounds, sulphurised olefins, metal dihydrocarbyldithio- phosphates (such as zinc dialkyldithiophosphates), thiocarbamate -containing compounds, such as thiocarbamate esters, thiocarbamate amides, thiocarbamic ethers, alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl) disulp hides.

[0107] In one embodiment the oil soluble phosphorus amine salt antiwear agent includes an amine salt of a phosphorus acid ester or mixtures thereof. The amine salt of a phosphorus acid ester includes phosphoric acid esters and amine salts thereof; dialkyldithiophosphoric acid esters and amine salts thereof; amine salts of phosphites; and amine salts of phosphorus -containing carboxylic esters, ethers, and amides; and mixtures thereof. The amine salt of a phosphorus acid ester may be used alone or in combination.

[0108] In one embodiment the oil soluble phosphorus amine salt includes partial amine salt-partial metal salt compounds or mixtures thereof. In one embodiment the phosphorus compound further includes a sulphur atom in the molecule. In one embodiment the amine salt of the phosphorus compound may be ashless, i.e., metal-free (prior to being mixed with other components).

[0109] The amines which may be suitable for use as the amine salt include primary amines, secondary amines, tertiary amines, and mixtures thereof. The amines include those with at least one hydrocarbyl group, or, in certain embodiments, two or three hydrocarbyl groups. The hydrocarbyl groups may contain 2 to 30 carbon atoms, or in other embodiments 8 to 26, or 10 to 20, or 13 to 19 carbon atoms.

[0110] Primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as such fatty amines as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine and oleyamine. Other useful fatty amines include commercially available fatty amines such as "Armeen®" amines (products available from Akzo Chemicals, Chicago, Illinois), such as Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S and Armeen SD, wherein the letter designation relates to the fatty group, such as coco, oleyl, tallow, or stearyl groups.

[0111] Examples of suitable secondary amines include dim ethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine and ethylamylamine. The secondary amines may be cyclic amines such as piperidine, piperazine and morpholine.

[0112] The amine may also be a tertiary-aliphatic primary amine. The aliphatic group in this case may be an alkyl group containing 2 to 30, or 6 to 26, or 8 to 24 carbon atoms. Tertiary alkyl amines include monoamines such as tert- butylamine, tert-hexylamine, 1 -methyl- 1 -amino -cyclohexane, tert-octylamine, tert-decylamine, tertdodecylamine, tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine, tert-tetracosanylamine, and tert-octacosanylamine.

[0113] In one embodiment the phosphorus acid amine salt includes an amine with C l l to C14 tertiary alkyl primary groups or mixtures thereof. In one embodiment the phosphorus acid amine salt includes an amine with C14 to C 18 tertiary alkyl primary amines or mixtures thereof. In one embodiment the phosphorus acid amine salt includes an amine with C 18 to C22 tertiary alkyl primary amines or mixtures thereof.

[0114] Mixtures of amines may also be used in the invention. In one embodiment a useful mixture of amines is "Primene® 81R" and "Primene® JMT." Primene® 81R and Primene® JMT (both produced and sold by Rohm & Haas) are mixtures of C l l to C 14 tertiary alkyl primary amines and C 18 to C22 tertiary alkyl primary amines respectively.

[0115] In one embodiment oil soluble amine salts of phosphorus compounds include a sulphur-free amine salt of a phosphorus-containing compound may be obtained/obtainable by a process comprising: reacting an amine with either (i) a hydroxy-substituted di-ester of phosphoric acid, or (ii) a phosphorylated hydroxy- substituted di- or tri- ester of phosphoric acid. A more detailed description of compounds of this type is disclosed in International Application PCT/US08/051126 (or equivalent to US Application 11/627405).

[0116] In one embodiment the hydrocarbyl amine salt of an alkylphosphoric acid ester is the reaction product of a C 14 to C 18 alkylated phosphoric acid with Primene 81R™ (produced and sold by Rohm & Haas) which is a mixture of C I 1 to C 14 tertiary alkyl primary amines.

[0117] Examples of hydrocarbyl amine salts of dialkyldithiophosphoric acid esters include the reaction product(s) of isopropyl, methyl-amyl (4-methyl-2- pentyl or mixtures thereof), 2-ethylhexyl, heptyl, octyl or nonyl dithiophosphoric acids with ethylene diamine, morpholine, or Primene 81R™, and mixtures thereof.

[0118] In one embodiment the dithiophosphoric acid may be reacted with an epoxide or a glycol. This reaction product is further reacted with a phosphorus acid, anhydride, or lower ester. The epoxide includes an aliphatic epoxide or a styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octene oxide, dodecene oxide, and styrene oxide. In one embodiment the epoxide may be propylene oxide. The glycols may be aliphatic glycols having from 1 to 12, or from 2 to 6, or 2 to 3 carbon atoms. The dithiophosphoric acids, glycols, epoxides, inorganic phosphorus reagents and methods of reacting the same are described in U.S. Patent numbers 3,197,405 and 3,544,465. The resulting acids may then be salted with amines. An example of suitable dithiophosphoric acid is prepared by adding phosphorus pentoxide (about 64 grams) at 58 °C over a period of 45 minutes to 514 grams of hydroxypropyl 0,0-di(4-methyl-2-pentyl)phosphorodithioate (prepared by reacting di(4-methyl- 2-pentyl)-phosphorodithioic acid with 1.3 moles of propylene oxide at 25 °C). The mixture may be heated at 75 °C for 2.5 hours, mixed with a diatomaceous earth and filtered at 70 °C. The filtrate contains 1 1.8% by weight phosphorus, 15.2% by weight sulphur, and an acid number of 87 (bromophenol blue).

[0119] The dithiocarbamate-containing compounds may be prepared by reacting a dithiocarbamate acid or salt with an unsaturated compound. The dithiocarbamate containing compounds may also be prepared by simultaneously reacting an amine, carbon disulphide and an unsaturated compound. Generally, the reaction occurs at a temperature from 25 °C to 125 °C.

[0120] Examples of suitable olefins that may be sulphurised to form an the sulphurised olefin include propylene, butylene, isobutylene, pentene, hexane, heptene, octane, nonene, decene, undecene, dodecene, undecyl, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof and their dimers, trimers and tetramers are especially useful olefins. Alternatively, the olefin may be a Diels-Alder adduct of a diene such as 1 ,3-butadiene and an unsaturated ester, such as, butylacrylate.

[0121] Another class of sulphurised olefin includes fatty acids and their esters. The fatty acids are often obtained from vegetable oil or animal oil; and typically contain 4 to 22 carbon atoms. Examples of suitable fatty acids and their esters include triglycerides, oleic acid, linoleic acid, palmitoleic acid or mixtures thereof. Often, the fatty acids are obtained from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof. In one embodiment fatty acids and/or ester are mixed with olefins.

[0122] In an alternative embodiment, the ashless antiwear agent may be a monoester of a polyol and an aliphatic carboxylic acid, often an acid containing 12 to 24 carbon atoms. Often the monoester of a polyol and an aliphatic carboxylic acid is in the form of a mixture with a sunflower oil or the like, which may be present in the friction modifier mixture from 5 to 95, in several embodiments from 10 to 90, or from 20 to 85, or 20 to 80 weight percent of said mixture. The aliphatic carboxylic acids (especially a monocarboxylic acid) which form the esters are those acids typically containing 12 to 24, or from 14 to 20 carbon atoms. Examples of carboxylic acids include dodecanoic acid, stearic acid, lauric acid, behenic acid, and oleic acid.

[0123] Polyols include diols, triols, and alcohols with higher numbers of alcoholic OH groups. Polyhydric alcohols include ethylene glycols, including di-, tri- and tetraethylene glycols; propylene glycols, including di-, tri- and tetrapropylene glycols; glycerol; butane diol; hexane diol; sorbitol; arabitol; mannitol; sucrose; fructose; glucose; cyclohexane diol; erythritol; and penta- erythritols, including di- and tripentaerythritol. Often the polyol is diethylene glycol, triethylene glycol, glycerol, sorbitol, penta erythritol or dipentaerythritol.

[0124] The commercially available monoester known as "glycerol monooleate" is believed to include 60 + 5 percent by weight of the chemical species glycerol monooleate, along with 35 + 5 percent glycerol dioleate, and less than 5 percent trioleate and oleic acid. The amounts of the monoesters, described above, are calculated based on the actual, corrected, amount of polyol monoester present in any such mixture.

Extreme Pressure Agents

[0125] Extreme Pressure (EP) agents that are soluble in the oil include sulphur- and chlorosulphur-containing EP agents, chlorinated hydrocarbon EP agents and phosphorus EP agents. Examples of such EP agents include chlorinated wax; sulphurised olefins (such as sulphurised isobutylene), organic sulphides and polysulphides such as dibenzyldisulphide, bis-(chlorobenzyl) disulphide, dibutyl tetrasulphide, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene, sulphurised terpene, and sulphurised Diels-Alder adducts; phosphosulphurised hydrocarbons such as the reaction product of phosphorus sulphide with turpentine or methyl oleate; phosphorus esters such as the dihydrocarbon and trihydrocarbon phosphites, e.g., dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphite; metal thiocarbamates such as zinc dioctyldithio carbamate and barium heptylphenol diacid; amine salts of alkyl and dialkylphosphoric acids or derivatives including, for example, the amine salt of a reaction product of a dialkyldithiophosphoric acid with propylene oxide and subsequently followed by a further reaction with P₂0₅; and mixtures thereof (as described in US 3,197,405).

[0126] Corrosion inhibitors that may be useful in the compositions of the invention include fatty amines, octyl octanamide, condensation products of dodecenyl succinic acid or anhydride and a fatty acid such as oleic acid with a polyamine.

[0127] Foam inhibitors that may be useful in the compositions of the invention include copolymers of ethyl acrylate and 2-ethylhexylacrylate and optionally vinyl acetate; demulsifiers including trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene oxide- propylene oxide) polymers.

[0128] Pour point depressants that may be useful in the compositions of the invention include polyalphaolefms, esters of maleic anhydride-styrene copolymers, poly(meth)acrylates, polyacrylates or polyacrylamides.

[0129] Friction modifiers that may be useful in the compositions of the invention include fatty acid or fatty alkyl derivatives such as amines, esters, epoxides, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines and amine salts of alkylphosphoric acids. Other friction modifiers include fatty derivatives of hydroxyl carboxylic acids such as dialkyl tartrates, alkyl tartrimides, or citrate esters.

Industrial Application

[0130] The method and lubricating composition of the invention may be suitable for refrigeration lubricants, greases, gear oils, axle oils, drive shaft oils, traction oils, manual transmission oils, automatic transmission oils, metal working fluids, hydraulic oils, or internal combustion engine oils .

[0131] In one embodiment the method and lubricating composition of the invention may be suitable for at least one of gear oils, axle oils, drive shaft oils, traction oils, manual transmission oils or automatic transmission oils. In one embodiment the invention provides a method of lubricating a manual transmission.

[0132] An automatic transmission includes continuously variable transmissions (CVT), infinitely variable transmissions (IVT), toroidal transmissions, continuously slipping torque converter clutches (CSTCC), stepped automatic transmissions or dual clutch transmissions (DCT).

[0133] The use (may also be referred to as a method) and copolymer composition described herein is capable of providing a lubricant with at least one (or at least two, or all) of acceptable or improved shear stability, acceptable or improved viscosity index control, acceptable or improved oxidation control, and acceptable or improved low temperature viscosity. The copolymer may be employed as an oil of lubricating viscosity in the presence or absence of other base oils.

[0134] When the copolymer with pendant groups further includes a nitrogen containing compound, the copolymer may further have acceptable/improved dispersancy properties (cleanliness) and oxidation control.

[0135] The internal combustion engine may be a 2-stroke or 4-stroke engine. Suitable internal combustion engines include marine diesel engines, aviation piston engines, low-load diesel engines, and automobile and truck engines. [0136] In several embodiments a suitable lubricating composition includes the copolymer present (on an actives basis) in ranges as shown in the following table.

Table

Embodiments (wt % of lubricant composition) A B C D

Star Polymer 0.1-30 2-30 5-20 8-15

Substantially Linear Polymer 0.1-50 2-40 5-30 8-20

Other Performance Additives 0-15 0.01-15 0.5-10 0.5-10

Oil of Lubricating Viscosity 5-99.8 15-95.99 40-89.5 55-85.5

Embodiments (wt % of lubricant composition) E F G H

Star Polymer 0.1-20 0.2-15 0.5-10 1 -8 Substantially Linear Polymer 0.1-50 2-40 5-30 8-20 Other Performance Additives 0-15 0.01-15 0.5-10 0.5-10 Oil of Lubricating Viscosity 5-99.7 15-97.79 40-94 55-90.5

Footnote: The star polymer and the substantially linear polymer are those described herein as part of the invention.

[0137] The weight percent of the star polymer and the substantially linear polymer may also be in the following ranges 5 wt % to 20 wt % of star polymer and 5 wt % to 15 wt % of the substantially linear polymer of the lubricating composition disclosed herein. The weight percent of the star polymer and the substantially linear polymer may also be in the following ranges 8 wt % to 15 wt % of star polymer and 5 wt % to 10 wt % of the substantially linear polymer of the lubricating composition disclosed herein.

[0138] The weight ratio of the star polymer to the substantially linear polymer may also vary from 6: 1 to 1 : 1 , or 4: 1 to 1.1 , or 3 : 1 to greater than 2: 1. A ratio closer to 2: 1 may begin to become less shear stable than ratios greater than 2: 1. In other embodiments, the ratio may be 0.02: 1 to 18: 1 , and in yet other embodiments, the ratios may be 0.04: 1 to 9: 1 or 0.1 : 1 to 4: 1 or 0.2: 1 to 2: 1. The following examples provide an illustration of the invention. These examples are non exhaustive and are not intended to limit the scope of the invention.

EXAMPLES

[0139] Star Polymers 1 to 13 (SP1 to SP13): Polymers are the same as those disclosed on page 32, paragraph [0100] of International Publication WO 2006/047393 (equivalent to US Publication 2009-01 18150) respectively, except monomer B (as is shown in Table 9 of WO 2006/047393) is methyl methacrylate.

[0140] Substantially linear polymers 1 to 8 (SLP1 to SLP8) with a weight average molecular weight of 45,000 or less are disclosed in International Application PCT/US09/052028 (filed 29 July, 2009 by Barton et al. , now WO2010/014655) respectively; see examples Cppl to Cpp8 in paragraphs [0140] and [0141].

[0141] Comparative Example 1 (CE1) is a manual transmission lubricant based on an API Group III base oil further containing 0.45 wt % of one or more corrosion inhibitors, 0.75 wt % of one or more antioxidants, 0.68 wt % of one or more antiwear agents, 0.62 wt % of one or more detergents, 1.5 wt % of one or more dispersants, 1 wt % of one or more pour point depressant, 0.02 wt % of one or more antifoam agent and 20 wt % of the copolymer of SLP 1.

[0142] Comparative Example 2 (CE2) is manual transmission lubricant similar to CE1 , except it contains 16 wt % of the polymer of SP1 1.

[0143] Invention lubricant 1 (INVL1) is a manual transmission lubricant similar to CE1 , except the copolymer of SLP 1 is present at 1 1 wt % and the polymer of SP13 is present at 10 wt %.

[0144] The manual transmission lubricants are evaluated using the following test procedures: ASTM D445 (Kinematic Viscosity (KV) at 40 °C and 100°C, ASTM D2983 (Brookfield Viscosity (BV) are determined at -40°C), D2270 (Viscosity Index (VI)), KRL tapered bearing shear stability test (KRL Test), and an Energy Loss test

[0145] The lubricating compositions are subjected to shear as determined by KRL tapered bearing shear stability test employing a 4 -ball wear test instrument as is used in CEC DIN 51350 Part 6 test procedure. The instrument is run for 20 hours with a 5000 N load, at 140 °C and at 1450 rpm. The viscosity data obtained from the test is described in ASTM method D445.

[0146] Energy loss data and maximum temperature of gearbox are measured as is described below. A transverse 5 -speed gearbox modified by locking the gear differential in fourth gear. The gearbox input is driven by an electric motor and the output load applied by a dynamometer; the size of each should be suitable for the test profile. The gear box is mounted in a temperature controlled environment, capable of maintaining a temperature of -7 °C. The gearbox is pre- soaked at -7 °C for at least 60 minutes. The low power NEDC test cycle is used throughout the test. The input speed for the NEDC cycle is calculated to match the correct output/road speed using available tyre diameters and gear ratios. In a similar manner the applied load is calculated from the NEDC test cycle using the assumptions of a medium sector passenger car, tyre diameter, and gear ratios. The output from the test is the sump temperature and energy absorbed at the end of each stage. These are measure via a thermocouple in the gearbox sump and input/output torque transducers. The test is performed in triplicate. The results reported are the average based on the three runs. Typically better results are obtained for samples with a lower temperature at the end of stage 5, and for samples with lower energy loss values.

[0147] The results obtained for viscometrics evaluations are:

[0148] The results obtained for energy loss and maximum temperature (°C)

[0149] The results indicate that the example of the invention has an improved shear stability, has lost less energy and has reduced operating temperature compared to either of the comparative examples.

[0150] It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. The products formed thereby, including the products formed upon employing lubricant composition of the present invention in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present invention; the present invention encompasses lubricant composition prepared by admixing the components described above.

[0151] Each of the documents referred to above is incorporated herein by reference. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word "about." Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention may be used together with ranges or amounts for any of the other elements.

[0152] As used herein, the term "(meth) acrylic" and related terms includes both acrylic and methacrylic groups.

[0153] As used herein, the term "a primary alcohol branched at the β- or higher position" relates to an alcohol with branching at the 2- position or a higher position (e.g., 3-, or 4-, or 5-, or 6-, or 7- position etc.)

[0154] As used herein the number of carbon atoms present in the ester groups of the polymers of the invention is counted to include only those carbon atoms of the alcohol-derived portion of the ester group. Specifically, the number of carbon atoms excludes the carbonyl carbon of the ester.

[0155] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: hydrocarbon substituents, including aliphatic, alicyclic, and aromatic substituents; substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent; and hetero substituents, that is, substituents which similarly have a predominantly hydrocarbon character but contain other than carbon in a ring or chain. A more detailed definition of the term "hydrocarbyl substituent" or "hydrocarbyl group" is described in paragraphs [01 18] to [01 19] of International Publication WO2008147704 (a similar description of hydrocarbyl is also described in paragraphs [0137] to [0141] of published application US 2010- 0197536.

[0156] While the invention has been explained in relation to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Claims

3757

What is claimed is:

1. A lubricating composition comprising (a) an oil of lubricating viscosity, (b) a star polymer, and (c) a substantially linear polymer with a weight average molecular weight of 45,000 or less.

2. The lubricating composition of claim 1, wherein the substantially linear polymer has a weight average molecular weight of 35,000 or less, or 25,000 or less, or 8000 to 25,000.

3. The lubricating composition of claim 1 , wherein the substantially linear polymer has a weight average molecular weight of 12,000 to 20,000.

4. The lubricating composition of any preceding claim, wherein the substantially linear polymer is a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with an alcohol.

5. The lubricating composition of any preceding claim, wherein the substantially linear polymer is a copolymer derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof,

wherein 0.1 to 99.89 percent of the carboxylic acid units are esterified with a linear alcohol or an alpha-branched alcohol,

wherein 0.01 to 10 % of the carboxylic acid units has at least one of an amino-, amido- and/or imido- group, and

wherein the copolymer has a reduced specific viscosity of up to 0.08. 6. The lubricating composition of any preceding claim, wherein the substantially linear polymer is a copolymer comprising units derived from monomers (i) an a-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer, prior to esterification has a reduced specific viscosity of up to 0.2, or up to 0.15, or up to 0.10, or up to 0.08.

7. The lubricating composition of any preceding claim, wherein the substantially linear polymer is a copolymer comprising units derived from monomers (i) an α-olefm and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position, wherein the copolymer, prior to esterification has a reduced specific viscosity of 0.02 to 0.07, 0.03 to 0.07 or 0.04 to 0.06.

8. The lubricating composition of any preceding claim, wherein the substantially linear polymer is a poly(meth)acrylate polymer, typically a polymethacrylate.

9. The lubricating composition of claim 8, wherein the poly(meth)acrylate has units derived from a mixture of alkyl (meth)acrylate ester monomers containing (a) 8 to 24, or 12 to 18, or to 15 carbon atoms in the alcohol-derived portion of the ester group and (b) 6 to 1 1 , or 8 to 1 1 , or 8 carbon atoms in the alcohol-derived portion of the ester group, and which have 2-(C_1-4 alkyl)-substituents, and optionally, at least one monomer selected from the group consisting of (meth)acrylic acid esters containing 1 to 7 carbon atoms in the alcohol-derived portion of the ester group and which are different from (meth)acrylic acid esters (a) and (b), vinyl aromatic compounds (or vinyl aromatic monomers); and nitrogen-containing vinyl monomers; provided that no more than 60% by weight, or no more than 50% by weight, or no more than 35% by weight of the esters contain not more than 10 carbon atoms in the alcohol- derived portion of the ester group.

10. The lubricating composition of any preceding claim, wherein the substantially linear polymer is present at 2 wt % to 40 wt %, or 5 wt % to 30 wt %, or 8 wt % to 20 wt % of the lubricating composition.

1 1. The lubricating composition of any preceding claim, wherein the substantially linear polymer is a copolymer comprising units derived from monomers (i) an α-olefm and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with a primary alcohol branched at the β- or higher position; and wherein the substantially linear polymer is present at 2 wt % to 40 wt %, or 5 wt % to 30 wt %, or 8 wt % to 20 wt % of the lubricating composition.

12. The lubricating composition of any preceding claim, wherein the star polymer has a random, tapered, di -block, tri-block, or multi-block architecture.

13. The lubricating composition of any preceding claim, wherein the star polymer is obtained from a RAFT or ATRP polymerisation process.

14. The lubricating composition of any preceding claim, wherein the star polymer is a polymethacrylate or mixtures thereof.

15. The lubricating composition of any preceding claim, wherein the star polymer is a poly(meth)acrylate (typically a polymethacrylate), and wherein the star polymer is derived from a monomer composition comprising:

(a) 50 wt % to 100 wt % of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 10 to 30, or 10 to 20, or 12 to 18, or 12 to 15 carbon atoms, or mixtures thereof;

(b) 0 wt % to 40 wt % of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 1 to 9, or 1 to 4 carbon atoms (for example methyl, butyl, or 2-ethylhexyl), or mixtures thereof; and

(c) 0 wt % to 10 wt % of a nitrogen-containing monomer.

16. The lubricating composition of any preceding claim, wherein the star polymer is a poly(meth)acrylate (typically a polymethacrylate), and wherein the star polymer is derived from a monomer composition comprising:

(a) 65 wt % to 95 wt % of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 12 to 18, or 12 to 15 carbon atoms, or mixtures thereof;

(b) 5 wt % to 30 wt % of an alkyl (meth)acrylate, wherein the alkyl group of the (meth)acrylate has 1 to 9, or 1 to 4 carbon atoms (for example methyl, butyl, or 2-ethylhexyl), or mixtures thereof; and

(c) 0 wt % to 5 wt % of a nitrogen-containing monomer.

17. The lubricating composition of any preceding claim, wherein the star polymer is a polymethacrylate and present at 2 wt % to 30 wt %, or 5 wt % to 20 wt %, or 8 wt % to 15 wt % of the lubricating composition.

18. The lubricating composition of any of claims 1 through 17 wherein the star polymer is a polymethacrylate and is present at 0.5 to 10 wt % of the lubricating composition.

20. The lubricating composition of any preceding claim, wherein the lubricating composition contains 0.3 wt % to 15 wt % of star polymer and 1 wt % to 35 wt % of the substantially linear polymer.

21. The lubricating composition of any preceding claim, wherein the lubricating composition contains 0.45 wt % to 5 wt % of star polymer and 2 wt % to 25 wt % of the substantially linear polymer.

22. A method of lubricating a mechanical device (typically a driveline device such as a manual transmission) comprising supplying to the device a lubricating composition of any preceding claim 1 to 21.