TITLE
LUBRICANTS CONTAINING BLENDS OF POLYMERS
BACKGROUND
[0001] The disclosed technology relates to lubricant formulations containing a
mixture of viscosity modifying polymers: a (meth)acrylate-containing polymer
comprising a multiplicity of arms, and an ethylene/olefin copolymer comprising
polymerized propylene monomers.
[0002] Viscosity modifiers including star polymers and other polymers with
multiplicity of arms are known in the field of lubricants for providing viscosity index
performance, low temperature performance as described by Brookfield viscosity and
higher temperature performance as indicated by kinematic viscosity performance at
40°C and 100°C. The viscosity modifier's performance has been observed in a wide
variety of mechanical devices including hydraulic systems, driveline systems, and
internal combustion engines. Olefin copolymers are also known as viscosity modifiers.
[0003] There is a continuing need to further improve the viscometric properties of
lubricating oils in a variety of applications, such as engine lubricants, motorcycle
lubricants (which typically lubricate both the engine and the transmission), driveline
lubricants (manual and automatic transmissions and gears), greases, and hydraulic
applications. It is particularly desirable to provide lubricants that have an increased
(improved) viscosity index and reduced kinematic viscosities such as at 40°C, as well
as increased (improved) high temperature-high shear rate viscosity, while maintaining
good or even improved other lubricant performance characteristics including good
antiwear performance or friction performance. In certain embodiments, such as, for
examples, lubricants for motorcycle engines, lubricants as described herein may exhibit
one or more of good shear stability under operating conditions characteristic of a
motorcycle gearbox, good gear protection, and good deposit performance.
[0004] EP 2 610 332, Lubrizol, July 3, 2013, discloses star polymers and lubricat
ing compositions thereof. The star polymer has at least two inner blocks, at least one
of which is in turn bonded to one or more outer blocks. The lubricant composition
may further comprise a viscosity modifier (typically an olefin copolymer such as an
ethylene-propylene copolymer).
[0005] U.S. Patent 8,513,176, Baum et al., August 20, 2013, discloses a process
for preparing a polymer, involving a chain transfer agent containing a thiocarbonyl
compound. The product may be a star polymer which may be a block-arm star poly
mer or a hetero-arm star polymer. Optionally other performance additives may be
present in a lubricant, including viscosity modifiers.
[0006] U.S. Application 2010/0190671, Stoehr et al, July 29, 2010, discloses use
of comb polymers for reducing fuel consumption. Also disclosed is a lubricant oil
formulation comprising the comb polymer which contains in the main chain at least
one repeat unit obtained from a polyolefin-based macromonomer. It may also contain
an additional additive, which may be, among others, a viscosity index improver.
Conventional viscosity index improvers may include olefin copolymers, especially of
the poly(ethylene-co-propylene) type.
[0007] U.S. Application 2008/0015131, Vinci et al., January 17, 2008, discloses
lubricants containing an olefin copolymer and an acrylate copolymer. A disclosed
polymer is an ethylene aliphatic olefin copolymer wherein the aliphatic olefin con
tains from 3 to about 24 carbon atoms, the copolymer having M ranging from about
600 to about 5000. In one embodiment the ethylene content may be about 20 mole %
to about 85 mole %. Preferably the copolymer is an ethylene-propylene copolymer.
The lubricant compositions are said to exhibit good low temperature and shear
stability performance. The lubricants include automatic transmission, manual trans
mission, and gear lubricants.
[0008] U.S. Application 2003-0036488, Yuki et al., February 20, 2003, discloses
a viscosity index improver and lubricant oil containing the same. The viscosity index
improver may include such monomers as 2-decyl-tetradecyl methacrylate, 2-dodecylhexadecyl
methacrylate, or 2-decyl-tetradecyloxyethyl methacrylate.
[0009] The disclosed technology, therefore, provides lubricants that may have one
or more of various beneficial properties, such as reduced vane and ring wear in a
hydraulic fluid formulation, and good viscosity properties such as viscosity index in
an engine or motorcycle lubricant.
SUMMARY
[0010] The disclosed technology provides a lubricant composition comprising:
(a) an oil of lubricating viscosity; (b) a (meth)acrylate-containing polymer comprising
a multiplicity of arms, wherein the arms contain at least 20, or at least 50 or 100
or 200 or 350 or 500 or 1000, carbon atoms, said arms being attached to a multivalent
organic moiety; and (c) an ethylene/olefin copolymer having a weight average
molecular weight of 5,000 to 250,000 or 10,000 to about 250,000, wherein the
copolymer comprises about 40 to about 70 weight percent polymerized ethylene
monomers and further comprises one or more polymerized olefin monomers of 3 to 6
carbon atoms (such as a-olefms).
[0011] The disclosed technology further provides amethod for lubricating a
mechanical device comprising supplying thereto the foregoing lubricant composition.
DETAILED DESCRIPTION
[0012] Various preferred features and embodiments will be described below by
way of non-limiting illustration.
Oil of Lubricating Viscosity
[0013] One component of the disclosed lubricants will be an oil of lubricating
viscosity. Such oils include natural and synthetic oils, oil derived from hydrocracking,
hydrogenation, and hydrofinishing, 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 more detailed description of natural and synthetic lubricating oils is described in
paragraphs [0058] to [0059] respectively of WO2008/147704. Synthetic oils may also
be produced by Fischer-Tropsch reactions and typically may be hydroisomerized
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.
[0014] 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." The oil of lubricating viscosity may also be an ester. A summary of the
API oil classifications is as follows:
Base Oil Category Sulfur (%) Saturates(%) Viscosity Index
Group I >0.03 and/or <90 80 to 120
Group II <0.03 and >90 80 to 120
Group III <0.03 and >90 >120
Group IV All polyalphaolefms (PAOs)
Group V All others not included in Groups I, II, III or IV
Groups I, II and III are mineral oil base stocks. In one embodiment the oil of lubricat
ing viscosity may be an API Group I oil. In other embodiment, it may be a Group II
or Group III oil, or any one of groups I through V.
[0015] 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 disclosed technology and the other performance additives.
[0016] The lubricating composition may be in the form of a concentrate and/or a
fully formulated lubricant. If the star polymer of the disclosed technology 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 components the star polymer of the
disclosed technology 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.
(Meth)acrylate polymer with multiple arms
[0017] The disclosed lubricant will also contain a (meth)acrylate-containing
polymer comprising a multiplicity of arms containing at least about 20, or at least 50
or 100 or 200 or 350 or 500 or 1000, carbon atoms, said arms being attached to a
multivalent organic moiety. As used herein, the term (meth)acrylate and its cognates
means either methacrylate or acrylate, as will be readily understood. The multi-armed
polymer may thus be characteristic of a "star" polymer, a "comb" polymer, or a
polymer otherwise having multiple arms or branches as described herein.
Star polymers
[0018] Star polymers are known. They may be prepared by a number of routes,
including atom transfer radical polymerization (ATRP), reversible additionfragmentation
chain transfer (RAFT) polymerization, nitroxide mediated polymeriza
tion, or anionic polymerization. A detailed discussion of ATRP is given in Chapter
11, pages 523 to 628 of the Handbook of Radical Polymerization, Edited by Krzysztof
Matyjaszewski and Thomas P. Davis, John Wiley and Sons, Inc., 2002 (hereinafter
referred to as "Matyjaszewski"). See in particular reaction scheme 11.1 on page 524,
11.4 on page 556, 11.7 on page 571, 11.8 on page 572, and 11.9 on page 575.
ATRP
[0019] In one embodiment, ATRP may be used to prepare a star polymer having
as a core portion a functional group of formula (I):
wherein R is hydrogen or a linear or branched alkyl group containing 1 to 5 carbon
atoms; A is an amino or alkoxy group connected through the nitrogen or oxygen atom
thereof to the remainder of the structure (I); and Y is a halogen such as bromine,
chlorine, fluorine, or iodine. The halogen may be derived from a suitable halogencontaining
compound such as an initiator, including those that contain one or more
atoms or groups of atoms which may be transferred by a radical mechanism under the
polymerization conditions. In one embodiment, the structure of (I) may be drawn in
more detail as structure (Iz
where Z is a polymeric group such as a crosslinked polymeric group. More detail on
ATRP processes is given in US patent 6,391,996 and U.S. Application
2007/0244018, referring therein to paragraphs 0133 to 0144.
[0020] Examples of a halogen containing compound include benzyl halides, such
as p-chloromethylstyrene, a-dichloroxylene, a,a-dichloroxylene, a,a-dibromoxylene
and hexakis(a-bromomethyl)benzene, benzyl chloride, benzyl bromide, 1-bromo-lphenylethane
and 1-chloro-l -phenylethane; carboxylic acid derivatives which are
halogenated at the a-position, such as propyl 2-bromopropionate, methyl 2-chloropropionate,
ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromoisobutyrate;
tosyl halides such as p-toluenesulfonyl chloride; alkyl halides such as
tetrachloromethane, tribromomethane, 1-vinylethyl chloride, 1-vinylethyl bromide;
and halogen derivatives of phosphoric acid esters, such as dimethylphosphoric acid.
[0021] In one embodiment when the halogen compound is employed, a transition
metal such as copper may also be present. The transition metal may be in the form of
a salt. The transition metal is capable of forming a metal to ligand bond and the ratio
of ligand to metal depends on the dentate number of the ligand and the coordination
number of the metal. The ligand is a nitrogen or phosphorus containing ligand. In one
embodiment the ligand is phosphorus-containing with triphenyl phosphene (PPI13) a
common ligand. A suitable transition metal for a triphenyl phosphene ligand includes
Rh, Ru, Fe, Re, Ni or Pd.
RAFT
[0022] RAFT polymerization may be employed when the core portion of the
polymer contains a functional group of formula (I) above wherein Y is represented
by -S-C(=S)-R5 where R5 may be an alkyl radical containing 1 to 20 carbon atoms.
The Y functionality may be derived from or be a portion of a chain transfer agent. In
certain embodiments the core portion comprises a functional group (often from a
chain transfer agent) derived from a compound comprising a thiocarbonyl thio group
and a free radical leaving groups, such as those disclosed in paragraph 0146 of U.S.
Application 2007/0244018.
[0023] Examples of RAFT chain transfer agents include benzyl l-(2-
pyrrolidinone)carbodithioate, benzyl (l,2-benzenedicarboximido)carbodithioate, 2-
cyanoprop-2-yl 1-pyrrolecarbodithioate, 2-cyanobut-2-yl 1-pyrrolecarbodithioate,
benzyl 1-imidazolecarbodithioate, N,N-dimethyl-S-(2-cyanoprop-2-
yl)dithiocarbamate, N,N-diethyl-S-benzyl dithiocarbamate, cyanomethyl l-(2-
pyrrolidone)carbodithoate, cumyl dithiobenzoate, N,N-diethyl S-(2-ethoxycarbonylprop-
2-yl)dithiocarbamate, 0-ethyl-S-(l -phenylethyl)xanthtate, O-ethyl-S-
(2-(ethoxycarbonyl)prop-2-yl)xanthate, 0-ethyl-S-(2-cyanoprop-2-yl)xanthate, Oethyl-
S-(2-cyanoprop-2-yl)xanthate, O-ethyl-S-cyanomethyl xanthate, O-phenyl-Sbenzyl
xanthate, O-pentafluorophenyl-S-benzyl xanthate, 3-benzylthio-5,5-
dimethylcyclohex-2-ene-l-thione or benzyl 3,3-di(benzylthio)prop-2-enedithioate,
S,S'-bis-(a,a'-disubstituted-a"-acetic acid)-trithiocarbonate, S,S'-bis-
(a,a'-disubstituted-a''-acetic acid)-trithiocarbonate or S-alkyl-S'-(-(a,a'-disubstituteda"-
acetic acid)-trithiocarbonates, dithiobenzoic acid, 4-chlorodithiobenzoic acid,
benzyl dithiobenzoate, 1-phenylethyl dithiobenzoate, 2-phenylprop-2-yl dithiobenzoate,
1-acetoxyethyl dithiobenzoate, hexakis(thiobenzoylthiomethyl)benzene, 1,4-
bis(thiobenzoylthiomethyl)benzene, l,2,4,5-tetrakis(thiobenzoylthiomethyl)benzene,
l,4-bis-(2-(thiobenzoylthio)prop-2-yl)benzene, l-(4-methoxyphenyl)ethyl dithioben
zoate, benzyl dithioacetate, ethoxycarbonylmethyl dithioacetate, 2-
(ethoxycarbonyl)prop-2-yl dithiobenzoate, 2,4,4-trimethylpent-2-yl dithiobenzoate,
2-(4-chlorophenyl)prop-2-yl dithiobenzoate, 3-vinylbenzyl dithiobenzoate, 4-
vinylbenzyl dithiobenzoate, S-benzyl diethoxyphosphinyldithioformate, tert-butyl
trithioperbenzoate, 2-phenylprop-2-yl 4-chlorodithiobenzoate, 2-phenylprop-2-yl 1-
dithionaphthalate, 4-cyanopentanoic acid dithiobenzoate, dibenzyl tetrathioterephthalate,
dibenzyl trithiocarbonate, carboxymethyl dithiobenzoate or poly(ethylene
oxide) with dithiobenzoate end group or mixtures thereof.
[0024] RAFT polymerization is also described in greater detail in Chapter 12,
pages 629 to 690 of Matyjaszewski, especially pages 664 to 665.
Nitroxide mediated
[0025] In the case of nitroxide-mediated polymerization, the core portion of a
polymer may comprise a functional group of formula (I) above, wherein Y is an alkyl
nitroxide group, -0-N(R )(R ) where R6 and R may be alkyl groups of 1 to 8 carbon
atoms or wherein R6 and R may be joined together to form a ring. When nitroxidemediated
techniques are employed, in some instances a portion of styrene may be
desirable (for instance, the amount of (meth)acrylate may be less than 50 wt % of the
star polymer) to allow for a satisfactory polymer to be prepared using TEMPO based
derivatives, for the reasons stated in Matyjaszewski, page 477, section 10.4. Alternatively,
if non-TEMPO based nitroxide mediated techniques are employed using an
alicyclic nitroxide or nonquaternary nitroxide, the presence of styrene is not essential.
A list of compounds suitable for nitroxide-mediated techniques is given in Table
10.1, pages 479-481 of Matyjaszewski. Nitroxide-mediated polymerization is also
described in paragraphs 016-to 0163 of U.S. Application 2007/0244018.
[0026] The amount of the compound employed to impart halogen, nitroxide
group, or dithioether functionality into the core portion in one embodiment is 0.001
to 0.10 moles per mole of monomer, in another embodiment 0.001 to 0.05 moles per
mole of monomer, and in yet another embodiment 0.001 to 0.03 moles per mole of
monomer in the arms of the polymer.
Anionic
[0027] Anionic polymerization techniques have also been reported for preparation
of star polymers; see for instance WO 96/23012. It is generally recognized that
anionic polymerization processes require carefully controlled conditions to be able to
prepare star polymers, such as highly pure solvents, inert atmosphere substantially
free from water, low reaction temperatures, and use of alkali metal carbanioinic
initiators.
Star polymer, details
[0028] When the (meth)acrylate-containing polymer comprising a multiplicity of
arms is a star polymer, the polymer may comprise (i) a core portion comprising a
polyvalent (meth) acrylic monomer, oligomer or polymer thereof or a polyvalent
divinyl non-acrylic monomer, oligomer or polymer thereof; and (ii) at least two arms
of polymerized alkyl (meth)acrylate ester. The core portion will further comprise a
functional group of formu
wherein E is independently another part of the core, a polymeric arm or to a monomeric
species, or another structural unit as defined by formula (la); R1 is hydrogen or
a linear or branched alkyl group containing 1 to 5 carbon atoms; A is nitrogen or
oxygen; and Y is a free radical leaving group selected from the group consisting of
one or more atoms or groups of atoms which may be transferred by a radical mecha
nism under the polymerization conditions, a halogen, a nitroxide group,, or a dithio
ester group. Analogous to structure (Iz), the bond shown at the left of structure (la)
may typically be attached to a Z group, where Z is a polymeric group such as a
crosslinked polymeric group.
Arms
[0029] The arms of the star polymer will themselves be (meth)acrylate-containing
polymer or oligomer moieties, comprising (meth)acrylic moieties condensed with
alcohol moieties to provide alkyl groups. In certain embodiments, the arms of the star
polymer may be formed from alkyl (meth)acrylate esters containing up to 40 carbon
atoms in the alkyl group, or up to 30 carbon atoms, or 1 to 18 carbon atoms, or 1 to
15 carbon atoms, or 8 to 15, or 10 to 15, or 12 to 15 carbon atoms. In certain embod
iments, one or more of the arms comprises units derived from alkyl acrylate monomers.
[0030] In one embodiment the (meth)acrylate ester contains 98% to 100% of the
alkyl groups in the polymerized alkyl (meth)acrylate ester arms which contain 1 to 18
or 1 to 15 carbon atoms; and 0% to 2% of alkyl groups in the polymerized alkyl
(meth)acrylate ester arms which contain 19 to 30 or 16 to 30 carbon atoms.
[0031] In one embodiment the polymeric arms comprise an alkyl ester group
containing 10 to 15 carbon atoms present in at least 50 % to 100% of the alkyl
groups; an alkyl ester group containing 6 to 9 carbon atoms present at 0 % to 20 %,
30 % or 40 % of the alkyl groups; an alkyl ester group containing 1 to 5 carbon atoms
present at 0 % to 18 % or 20 % or 30 % of the alkyl groups; an alkyl ester group
containing 16 to 30 (or 16 to 18) carbon atoms present at 0 % to 2 % of the alkyl
groups; and a nitrogen containing monomer present at 0 wt % to 10 wt % of the
polymeric arms.
[0032] In one embodiment the polymeric arms comprise an alkyl ester group
containing 10 to 18 carbon atoms present in at least 50 % to 100% of the alkyl
groups; an alkyl ester alkyl group containing 6 to 9 carbon atoms present at 0 % to 20
%, 30 % or 40 % of the alkyl groups; an alkyl ester alkyl group containing 1 to 5
carbon atoms present at 0 % to 18 % or 20 % or 30 % of the alkyl groups; an alkyl
ester group containing 19 to 30 carbon atoms present at 0 % to 2 % of the alkyl
groups; and a nitrogen containing monomer present at 0 wt % to 10 wt % of the
polymeric arms.
[0033] The amount of the ester alkyl group containing 10 to 15 carbon atoms
present on the star polymer in one embodiment may be at least 50 % of the alkyl
groups, in another embodiment at least 60 % of the alkyl groups, in another embodi
ment at least 70 % of the alkyl groups and in another embodiment at least 80 % of the
alkyl groups. In one embodiment the amount of the ester alkyl group containing 10 to
15 carbon atoms may be at least 95 % or 98 %.
[0034] The amount of an ester alkyl group containing 6 to 9 carbon atoms present
on the star polymer in one embodiment is from 0 %to 15 % or 20 % or 30 % of the
alkyl groups, in another embodiment 0 %to 10 % of the alkyl groups and in another
embodiment 0 % to 5 % of the alkyl groups.
[0035] The amount of an ester alkyl group containing 1 to 5 carbon atoms present
on the star polymer in one embodiment is from 0 %to 13 % or 20 % or 30 % of the
alkyl groups, in another embodiment 0 %to 8 % of the alkyl groups and in another
embodiment 0 % to 3 % of the alkyl groups.
[0036] The amount of an ester alkyl group containing 16 to 30 carbon atoms
present on the star polymer in one embodiment is from 0 % to 1% of the alkyl
groups and in another embodiment 0 % of the alkyl groups.
[0037] Examples of the alkyl portion of a (meth)acrylate ester include those
derived from saturated alcohols, such as methyl methacrylate, butyl methacrylate, 2-
ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, isooctyl
(meth)acrylate, isononyl (meth)acrylate, 2-tert-butylheptyl (meth)acrylate, 3 isopropylheptyl
(meth)acrylate, 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, 5-isopropylheptadecyl
(meth)acrylate, 4-tert-butyloctadecyl (meth)acrylate, 5-ethyloctadecyl (meth)acrylate,
3-isopropyloctadecyl (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)acrylates 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. In certain embodiments the alkyl portion of the ester may be
derived from a b-branched alcohol having up to 30 carbon atoms.
[0038] The ester compounds 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 alcohol groups of various
chain lengths is generally obtained.
[0039] In one embodiment the star polymer is further functionalized in the core or
the polymeric arms with a nitrogen containing monomer. The nitrogen containing
monomer may include a vinyl substituted nitrogen heterocyclic monomer, a dialkylaminealkyl
(meth)acrylate monomer, a dialkylaminoalkyl (meth)acrylamide mono
mer, a tertiary-(meth)acrylamide monomer, or mixtures thereof.
[0040] In one embodiment the core or polymeric arms may comprise a
(meth)acrylamide or (meth)acrylate monomer of formula (Ila) or (lib) respectively:
wherein each Q is independently hydrogen or methyl and, in one embodiment, Q is
methyl; each R is independently hydrogen or hydrocarbyl group containing 1 to 8 or
1 to 4 carbon atoms; each R is independently hydrogen or hydrocarbyl group containing
1 to 2 carbon atoms and, in one embodiment, each R is hydrogen; and g is an
integer from 1 to 6 and, in one embodiment, g is 1 to 3.
[0041] Examples of a suitable nitrogen containing monomer include vinyl pyri
dine, N-vinyl imidazole, N-vinyl pyrrolidinone, and N-vinyl caprolactam, dimethylaminoethyl
acrylate, dimethylaminoethyl methacrylate, dimethylaminobutyl acryla
mide, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylamide, dimethylaminopropyl
ethacrylamide, dimethylaminoethyl acrylamide or mixtures thereof.
[0042] In one embodiment the polymer is reacted by copolymerization or grafting
onto or into the arms or core with an acylating agent and an amine to form a dispersant
viscosity modifier (often referred to as a DVM), thus named because such
materials exhibit both dispersant and viscosity modifying properties.
[0043] In one embodiment of the invention the polymeric arms or core (described
below) are functionalized by copolymerization or grafting, onto or into the arms or
core, with an acylating agent, an amine, or mixtures thereof. Examples of a grafting
acylating agent include an unsaturated carboxylic acid or anhydride or derivatives
thereof such as maleic anhydride, (meth) acrylic acid, or itaconic acid, which may
then, be reacted with a nitrogen compound such as an amine. In one embodiment the
acylating agent is a dicarboxylic acid or anhydride. Examples of a dicarboxylic acid
or anhydride thereof include itaconic anhydride, maleic anhydride, methyl maleic
anhydride, ethyl maleic anhydride, dimethyl maleic anhydride, or mixtures thereof.
[0044] In one embodiment the polymer, b, is further reacted with an amine to
form a condensed species such as an amide group a species with dispersant proper
ties. Examples of an amine include an amino hydrocarbyl substituted amine, such as
4-aminodiphenylamine, a hydrocarbyl substituted morpholine, such as 4 (3-aminopropyl)
morpholine or 4-(2-aminoethyl) morpholine or a dialkyl amino alkyl (meth)-
acrylate such as a dimethyl amino alkyl (meth)acrylate or N-vinyl pyrrolidinone. In
one embodiment the alkyl group of dimethyl amino alkyl (meth)acrylate is propyl and
in another embodiment ethyl. In certain embodiments the amine compound may
comprise an imidazolidinone, cyclic carbamate, or pyrroldininone represented by the
structure
wherein Hy is a hydrocarbylene group such as alkylene, or CI -4 alkylene or C2 alkylene,
and Hy' and Hy" are each independently hydrogen or hydrocarbyl groups
such as alkyl or CI -4 alkyl or C2 alkyl, and Q is >NH, >NR, >CH2, >CHR, >CR2,
or -0-, where R is CI -4 alkyl and " > " represents two bonds. Typically Q may be
>NH or >NR. In one embodiment the amine compound may be an imidazolinone
which may include 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.
[0045] In one embodiment the polymeric arms of the star polymer have a polydispersity
of 2 or less, in another embodiment 1.7 or less, in another embodiment 1.5 or
less, for instance, 1 to 1.4. In one embodiment the star polymer has polydispersity
with a bimodal or higher modal distribution. The bimodal or higher distribution is
believed to be partially due to the presence of varying amounts of uncoupled polymer
chains and/or uncoupled star-polymers or star-to-star coupling formed as the polymer
is prepared.
[0046] In one embodiment the star polymer has at least 3 arms, in another embodi
ment greater than 5 arms, in another embodiment greater than 7 arms, in another
embodiment greater than 10 arms, for instance 12 to 100, 14 to 50, or 16 to 40 arms. In
one embodiment the star polymer has 120 arms or less, in another embodiment 80 arms
or less, in another embodiment 60 arms or less. In certain embodiments there may be 3
to 20, 5 to 20, or 6 to 15, or 7 to 8 arms per star.
[0047] The star polymer moiety when formed may have uncoupled polymeric
arms present (also referred to as a polymer chain or linear polymer). The percentage
conversion of a polymer chain to star polymer in one embodiment is at least 10 %, in
another embodiment at least 20 %, in another embodiment at least 40 % and in
another embodiment at least 55 %, for instance 70 %, 75 % or 80%. In one embodi
ment the conversion of polymer chain to star polymer is about 90 %, 95 %, or 100%.
In one embodiment a portion of the polymer chains does not form a star polymer and
remains as a linear polymer. In one embodiment the linear polymer is substantially
free of or free of a halogen, a nitroxide group or a dithioether group. In one embodiment
the linear polymer has a substantially similar or identical composition and
weight average molecular weight as the star polymer arms containing a polymerized
alkyl (meth)acrylate ester.
[0048] In one embodiment one or more of the arms of the star polymer are diblock
AB type copolymers, in another embodiment tri-block ABA type copolymers,
in another embodiment tapered block polymers, and in another embodiment alternat
ing polymers.
[0049] The star polymer described above in one embodiment is a block-arm star
(co)polymer (where "(co)polymer" is used to mean "polymer or copolymer"), in
another embodiment a hetero-arm star (co)polymer (as described below) and in
another embodiment the star polymer is a tapered arm copolymer. A tapered arm
copolymer has a variable composition across the length of a polymer chain. For
example, the tapered arm copolymer will 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 polymer arm is more of a gradient composition of the two monomers.
Tapered block copolymers may be coupled to form block-arm star polymers.
[0050] The block-arm star (co)polymer contains one or more polymer arms
derived from two or more monomers within the same arm. A more detailed descrip
tion of the block-arm star polymer 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.).
[0051] The hetero-arm, or "mikto-arm," star polymer contains arms which may vary
from one another either in molecular weight, composition, or both, as defined in Hsieh et
al. For example, a portion of the arms of a given star polymer can be of one polymeric
type and a portion of a second polymeric type. More complex hetero-arm star polymers
may be formed by combining portions of three or more polymeric arms with a coupling
agent.
[0052] In certain embodiments the arms may be random copolymers. In certain
embodiments they may be copolymers of 73 to 85, or 78 to 84, percent by weight of
alkyl methacrylates having predominantly or exclusively 1 to 25 carbon atoms in the
alkyl group, 14 to 25, or 16 to 20, percent by weight methyl methacrylate monomers,
and 0.05 to 10, or 0.1 to 3, or 0.5 to 2, percent by weight alkyl methacrylate mono
mers having C6 to CIO carbon atoms in the alkyl groups, such as 2-ethylhexyl
methacrylate.
Core
[0053] In a star polymer, the polymeric arms will be attached to (or radiate from)
a core which itself will typically have a polymeric or oligomeric structure. The core
portion may be a polyvalent (meth) acrylic monomer, oligomer or polymer thereof or
a polyvalent divinyl non-acrylic monomer oligomer or polymer thereof. The polyva
lent monomer, oligomer or polymer thereof may be used alone or as a mixture.
[0054] In one embodiment the polyvalent divinyl non-acrylic monomer is a
divinyl benzene. In one embodiment the polyvalent (meth) acrylic monomer is 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 one
embodiment the polyvalent (meth) acrylic monomer is an acrylic or methacrylic acid
polyol or a condensation product of a polyamine.
[0055] The polyol in one embodiment contains 2 to 20 carbon atoms, or in other
embodiments 3 to 15 or 4 to 12; and the number of hydroxyl groups present in one
embodiment is 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-hexanene diol or triols such as trimethylolpropane, or oligomerized
trimethylolpropanes. Examples of a polyamine include polyalkylenepolyammes, such
as, ethylenediamine, diethylenetriamine, tri ethylenetetramine, tetraethylene pentamine,
pentaethylenehexamine and mixtures thereof.
[0056] Examples of the polyvalent unsaturated (meth) acrylic monomer include
ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacry
late, 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 dimethacry
late, 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 di
methacrylate, 1,1,1 -trimethylolpropane trimethacrylate, hexamethylenediol diacrylate
or hexamethylenediol dimethacrylate or an alkylene bis-(meth)acrylamide.
[0057] The amount of polyvalent coupling agent may be an amount suitable to
provide coupling of polymer previously prepared as arms onto a core comprising the
coupling agent in monomeric, oligomeric, or polymeric form, to provide a star
polymer. As described above, suitable amounts may be determined readily by the
person skilled in the art with minimal experimentation, even though several variables
may be involved. For example, if an excessive amount of coupling agent is employed,
or if excessive unreacted monomer from the formation of the polymeric arms remains
in the system, crosslinking rather than star formation may occur. Typically the mole
ratio of polymer arms to coupling agent may be 50:1 to 1.5:1 (or 1:1), or 30:1 to 2:1,
or 10:1 to 3:1, or 7:1 to 4:1, or 4:1 to 1:1. In other embodiments the mole ratio of
polymer arms to coupling agent may be 50:1 to 0.5:1, or 30:1 to 1:1, or 7:1 to 2:1.
The desired ratio may also be adjusted to take into account the length of the arms,
longer arms sometimes tolerating or requiring more coupling agent than shorter arms.
In certain embodiments, 1 to 5 parts by weight, or 2 to 4, or 2.5 to 3, parts by weight
of a coupling agent such as ethylene glycol dimethacrylate may be used to react with
pre-formed arms prepared with 100 parts by weight of (meth)acrylate monomers. If
desired, the polymer prepared by coupling arms with a coupling agent, may be further
treated or reacted with various monomers such as additional acrylate or methacrylate
monomers, e.g., methyl methacrylate, methyl acrylate, ethylhexyl methacrylate,
ethylhexyl acrylate, or lauryl methacrylate. Such further treatment may be with a
relatively minor amount of such monomer, e.g., 0.05 to 2 of 0.5 to 1.5 weight per
cent. Typically the material prepared will be soluble in an oil of lubricating viscosity.
[0058] In certain embodiments the arms of the star polymer may each inde
pendently have a number average molecular weight of 4,000 to 200,000, or 10,000 to
100,000, or 15,000 to 50,000, or 10,000 to 200,000, or 20,000 to 100,000, or 35,000
to 50,000.
[0059] In one embodiment the star polymer overall has a weight average molecular
weight (Mw) of 5000 to 1,000,000, in another embodiment 10,000 to 1,000,000, in
another embodiment 10,000 to 600,000 and in another embodiment 15,000 to 500,000
or 8,000 to 1,000,000 or 8,000 to 700,000. Examples of a suitable Mw include 15,000
to 350,000, 15,000 to 50,000, 150,000 to 280,000, or 25,000 to 140,000, or to 280,000,
or to 600,000.
[0060] In one embodiment the star polymer overall has a polydispersity (Mw/M )
greater than 1.3 or 2, in one embodiment 3 or more, in another embodiment 4 or more
and in another embodiment 5 or more. An upper range on the polydispersity may
include 30 or 20 or 15 or 10. Examples of suitable ranges include 1.3 to 30, 3 to 15 or
1.3 to 10. In one embodiment the star polymer comprises a mixture of star and linear
polymers. The polydispersity of said mixtures is the same as, or similar to, or slightly
larger than the ranges described immediately above.
Comb polymer
[0061] In another embodiment, the (meth)acrylate-containing polymer comprising
a multiplicity of arms may be a comb polymer, as described in greater detail in U.S.
patent 8,067,349. Such as material may comprise a main chain from which arms
emanate. The main chain may comprise repeat units derived from low molecular
weight monomers such as styrene or substituted styrene, alkyl(meth)acrylates having
1 to 10 carbon atoms in the alcohol (alkyl) group, vinyl esters, vinyl ethers, and other
such as described in claim 1 of US 8,067,349. There will also be a multiplicity of
polyolefin-based macromonomers which may have a number average molecular
weight in the range of 700 to 10,000, and which may also contain non-olefinic
monomers. The macromonomer will typically have exactly one polymerizable double
bond which may be a terminal bond. For example, a cationic polymerization of
isobutylene may form a polyisobutylene which has a terminal double bond. Typical
macromonomers may be prepared by reacting a macroamine (long chain amine) or a
macroalcohol (long chain alcohol), each based on a polyolefin, with methyl methac
rylate by an aminolysis or transesterification reaction. Further details of their synthe
sis are reported in the aforementioned US 8,067,349. The molecular weights and
compositions of the branches described above for the star polymers may also be
applied to the branches of the comb polymer.
[0062] Other polymers having a multiplicity of arms include those described in
U.S. Application 2003-0036488, Yuki et al., February 20, 2003. The materials
disclosed therein may include polymers prepared from monomers such as 2-decyltetradecyl
methacrylate, 2-dodecyl-hexadecyl methacrylate, or 2-decyltetradecyloxyethyl
methacrylate. Those particular monomers may have arms with 20
to 30 or 24 to 28 carbon atoms and may also contain ether functionality. In some
embodiments these arms have a branch at the b-position. In some embodiments the
alcohols from which they are derived are referred to as Guerbet alcohols. Guerbet
alcohols typically have one or more carbon chains with branching at the b- or
higher position. The Guerbet alcohols in general may contain, in various embodi
ments, 10 to 60, or 12 to 60, or 16 to 40, or 20 to 30 carbon atoms. Methods to
prepare Guerbet alcohols are disclosed in US Patent 4,767,815 (see column 5, line
39 to column 6, line 32). Correspondingly longer arms may also be used.
[0063] In some embodiments, for instance (but not exclusively) when the
(meth)acrylate-containing polymer with multiple arms is in the form of a comb
polymer, the arms may comprise hydrocarbyl groups or may comprise hydrocarbyl
monomer units. In one embodiment, the arms may be polymeric entities comprising
conjugated diene monomer units (optionally hydrogenated) or isobutylene monomer
units. In one embodiment, the conjugated diene may comprise butadiene, that is, 1,3-
butadiene or isoprene. (The expression "comprising [certain] monomer units" as used
herein is intended to refer to polymerized monomer units or "units derived from" the
indicated monomers by way of polymerization. It is understood that the monomer
units in their original, unpolymerized form, are not normally present in any signifi
cant amount, and there is no intention to suggest the contrary.)
[0064] The amount of the (meth)acrylate-containing polymer comprising a
multiplicity of arms is present in a lubricating composition in an amount of 0.1 to 5
percent by weight or 0.1 to 2.5 percent by weight, or 0.25 to 5 percent by weight, or
0.25 to 2.5 percent by weight, or 0.5 to 4, or 1 to 3.5, or 1.3 to 3.4, percent by weight.
It may also be provided as a concentrate in an oil or other medium, in which case its
amount within the concentrate will be correspondingly greater, such as 1 to 25 or 2.5
to 25 or to 50 percent by weight.
Olefin copolymer
[0065] The lubricant composition will also contain a second polymer which is an
ethylene/olefin copolymer having a weight average molecular weight of 5,000 to
250,000, or 10,000 to 250,000, or alternatively 10,000 to 200,000, or 20,000 to
180,000, or 15,000 to 150,000, or 20,000 to 100,000, or 20,000 to 80,000 or, alterna
tively, 100,000 to 200,000 or 100,000 to 180,000. This polymer may also be of a
form having long arms, although it may also be of a more conventional linear or
branched structure.
[0066] The second copolymer itself, the ethylene-olefin copolymer, will comprise
40 to 75 or 40 to 70 weight percent polymerized ethylene monomers and will further
comprise one or more polymerized olefin monomers of 3 to 6 carbon atoms. In
certain embodiments the olefin monomers may comprise at least one of propylene or
butylene monomer units, and in one embodiment may comprise propylene monomer
units. In certain embodiments the second polymer may comprise 40 to 50 percent by
weight ethylene monomer units and 50 to 60 percent by weight of the other olefin
monomer units such as propylene monomer units. Other monomers may also be
present, such as non-conjugated diene units, optionally hydrogenated, typically in an
amount of 0-10 percent by weight, or 1 to 5 percent.
[0067] The amount of the ethylene/olefin copolymer in a fully formulated lubri
cant may be 0.03 to 1, or 0.05 to 0.5, or 0.1 to 0.4, or 0.1 to 10, or 0.1 to 2.5 percent
by weight. It may also be provided as a concentrate in an oil or other medium, in
which case its amount within the concentrate will be correspondingly greater, such as
5 to 15 percent by weight. Both polymers may be present in the same concentrate at
the identified amounts.
[0068] Suitable olefin copolymers are well known and are described, for instance,
in U.S. Application 2008/0015131, Vinci et al. Such polymers are commercially
available as Lucant™ polymer, Trilene™ polymers, Nordel™ polymers, Paratone™
polymers, Lubrizol ® 70XY series polymers, and Royalene™ polymers.
[0069] Copolymers of aliphatic olefins may thus comprise an ethylene-aliphatic
olefin copolymer wherein the aliphatic olefins, typically alpha olefins, contain 3 to 24
carbon atoms, said copolymers having an Mn from 500 to 5000, such as 800 to 4000
or 2000 to 4000. At least some propylene monomer will typically be present. The
polydispersity (Mw/M ) may be from 1.1 to 3, such as 1.3 to 2.5 or 2.0 to 2.4. Such
polymers may be formed by copolymerization of ethylene and one or more aliphatic
olefins under conditions known in the art. Examples include polymerizations con
ducted using Ziegler-Natta or metallocene catalysts.
[0070] Other Components Other components that are commonly used in lubri
cants may also be present. One such material may be an overbased detergent. Overbased
materials, otherwise referred to as overbased or superbased salts, are generally
single phase, homogeneous Newtonian systems characterized by a metal content in
excess of that which would be present for neutralization according to the stoichiometry
of the metal and the particular acidic organic compound reacted with the metal.
The overbased materials may be prepared by reacting an acidic material (typically an
inorganic acid or lower carboxylic acid such as carbon dioxide) with a mixture
comprising an acidic organic compound, a reaction medium comprising at least one
inert, organic solvent (such as mineral oil, naphtha, toluene, xylene) for said acidic
organic material, a stoichiometric excess of a metal base, and a promoter such as a
phenol or alcohol. The acidic organic material will normally have a sufficient number
of carbon atoms to provide a degree of solubility in oil. The amount of excess metal
is commonly expressed in terms of metal ratio. The term "metal ratio" is the ratio of
the total equivalents of the metal to the equivalents of the acidic organic compound.
A neutral metal salt has a metal ratio of one. A salt having 4.5 times as much metal as
present in a normal salt will have metal excess of 3.5 equivalents, or a ratio of 4.5.
[0071] Such overbased materials are well known to those skilled in the art. They are
useful for a variety of purposes, including cleanliness and neutralization of acidic by
products of combustion when used in engine lubricants; they may also provide control of
friction or control of corrosion. Patents describing techniques for making basic salts of
sulfonic acids, carboxylic acids, phenols, phosphonic acids, and mixtures of any two or
more of these include U.S. Patents 2,501,731; 2,616,905; 2,616,91 1; 2,616,925;
2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and
3,629,109. Other detergents include salixarate detergents; they and methods for their
preparation are described in greater detail in U.S. patent number 6,200,936 and PCT
Publication WO 01/56968. Also known are salicylate detergents, described in greater
detail in U.S. Patents 4,710,023 and 3,372,1 16. In one embodiment the lubricant com
prises an overbased sulfonate detergent, an overbased phenol-containing detergent, or
mixtures there.
[0072] The amount of detergent in a fully formulated lubricant, if present, may be
0.01 to 15 percent by weight, or 0.1 to 5 , or 0.5 to 2, or 1 to 3 percent.
[0073] Dispersants are also well known additives in the field of lubricants and
include primarily what is known as ashless dispersants and polymeric dispersants.
Ashless dispersants are so-called because, as supplied, they do not contain metal and
thus do not normally contribute to sulfated ash when added to a lubricant. However
they may, of course, interact with ambient metals once they are added to a lubricant
which includes metal-containing species. Ashless dispersants are characterized by a
polar group attached to a relatively high molecular weight hydrocarbon chain. Typical
ashless dispersants include N-substituted long chain alkenyl succinimides, having
a variety of chemical structures including typically
where each R is independently an alkyl group, frequently a polyisobutylene group
with a molecular weight (Mn) of 500-5000 based on the polyisobutylene precursor,
and R are alkylene groups, commonly ethylene (C2H4) groups. Such molecules are
commonly derived from reaction of an alkenyl acylating agent with a polyamine, and
a wide variety of linkages between the two moieties is possible beside the simple
imide structure shown above, including a variety of amides and quaternary ammonium
salts. In the above structure, the amine portion is shown as an alkylene polyamine
such as polyethylene polyamine, although other aliphatic and aromatic mono- and
polyamines may also be used, such as amino diphenyl amine. Also, a variety of modes
of linkage of the R1 groups onto the imide structure are possible, including various
cyclic linkages. The dispersant may be formed by a process involving the use of
chlorine or by a thermal "ene" process or a free radical process. The average number
of succinic acid groups attached to an R1 group (e.g., polyisobutylene group) may be,
in certain embodiments, 1.1 to 2.0, or 1.15 to 1.35, 1.30 to 1.8, or 1.4 to 1.7. The ratio
of the carbonyl groups of the acylating agent to the nitrogen atoms of the amine may
be 1:0.5 to 1:3, and in other instances 1: 1 to 1:2.75 or 1:1.5 to 1:2.5. Succinimide
dispersants are more fully described in U.S. Patents 4,234,435 and 3,172,892 and in
EP 0355895.
[0074] Another class of ashless dispersant is high molecular weight esters. These
materials are similar to the above-described succinimides except that they may be
seen as having been prepared by reaction of a hydrocarbyl acylating agent and a
polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol. Such
materials are described in more detail in U.S. Patent 3,381,022.
[0075] Another class of ashless dispersant is Mannich bases. These are materials
which are formed by the condensation of a higher molecular weight, alkyl substituted
phenol, an alkylene polyamine, and an aldehyde such as formaldehyde. Such materi
als are described in more detail in U.S. Patent 3,634,515.
[0076] Other dispersants include polymeric dispersant additives, which are
generally hydrocarbon-based polymers which contain polar functionality to impart
dispersancy characteristics to the polymer.
[0077] Dispersants can also be post -treated by reaction with any of a variety of
agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon disulfide,
aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides,
nitriles, epoxides, boron compounds, and phosphorus compounds. References detailing
such treatment are listed in U.S. Patent 4,654,403. In one embodiment the lubri
cant composition comprises at least one boron-containing dispersant.
[0078] The amount of the dispersant in a fully formulated lubricant of the present
technology may be at least 0.1% of the lubricant composition, or at least 0.3% or 0.5%
or 1%, and in certain embodiments at most 9% or 8% or 6% or 4% or 3% or 2% by
weight.
[0079] The lubricant may also contain a metal salt of a phosphorus acid. Metal
salts of the formula
[(R 0)(R 0)P(=S)-S] -M
where R8 and R9 are independently hydrocarbyl groups containing 3 to 30 carbon
atoms, are readily obtainable by heating phosphorus pentasulfide (P2S5) and an
alcohol or phenol to form an 0,0-dihydrocarbyl phosphorodithioic acid. The alcohol
which reacts to provide the R8 and R9 groups may be a mixture of alcohols, for
instance, a mixture of isopropanol and 4-methyl-2-pentanol, and in some embodi
ments a mixture of a secondary alcohol and a primary alcohol, such as isopropanol
and 2-ethylhexanol. Other alcohols may include secondary-butyl alcohol or iso-octyl
alcohol. The resulting acid may be reacted with a basic metal compound to form the
salt. The metal M, having a valence n, generally is aluminum, lead, tin, manganese,
cobalt, nickel, zinc, or copper, and in many cases, zinc, to form zinc dialkyldithiophosphates.
Such materials are well known and readily available to those skilled in
the art of lubricant formulation. Suitable variations to provide good phosphorus
retention in an engine are disclosed, for instance, in US published application 2008-
0015129, see, e.g., claims.
[0080] The amount of the metal salt of a phosphorus acid in a completely
formulated lubricant, if present, will typically be 0.1 to 4 percent by weight, such as
0.5 to 2 percent by weight or 0.75 to 1.25 percent by weight. The amount may be, in
some embodiments, an amount which delivers phosphorus to the lubricant at 0.01 to
0.15 percent by weight, or 0.03 to 0.08, or 0.03 to 0.06 percent by weight.
[0081] Another component that may be used is a supplemental viscosity modifier,
which would be in addition to the combination of polymeric viscosity modifiers of
the disclosed technology, presented above. Viscosity modifiers (VM) and dispersant
viscosity modifiers (DVM) are well known. Examples of VMs and DVMs may
include polymethacrylates, polyacrylates, polyolefins, hydrogenated vinyl aromaticdiene
copolymers (e.g., styrene-butadiene, styrene-isoprene), styrene-maleic ester
copolymers, and similar polymeric substances including homopolymers, copolymers,
and graft copolymers. The DVM may comprise a nitrogen-containing methacrylate
polymer, for example, a nitrogen-containing methacrylate polymer derived from
methyl methacrylate and dimethylaminopropyl amine.
[0082] Examples of commercially available VMs, DVMs and their chemical types
may include the following: polyisobutylenes (such as Indopol™ from BP Amoco or
Parapol™ from ExxonMobil); olefin copolymers (such as Lubrizol™ 7060, 7065,
and 7067 from Lubrizol and Lucant™ HC-2000L and HC-600 from Mitsui); hydrogenated
styrene-diene copolymers (such as Shellvis™ 40 and 50, from Shell and
LZ® 7308, and 7318 from Lubrizol); styrene/maleate copolymers, which are disper
sant copolymers (such as LZ® 3702 and 3715 from Lubrizol); polymethacrylates,
some of which have dispersant properties (such as those in the Viscoplex™ series
from RohMax, the Hitec™ series of viscosity index improvers from Afton, and LZ®
7702, LZ® 7727, LZ® 7725 and LZ® 7720C from Lubrizol); olefin-graftpolymethacrylate
polymers (such as Viscoplex™ 2-500 and 2-600 from RohMax);
and hydrogenated polyisoprene star polymers (such as Shellvis™ 200 and 260, from
Shell). Viscosity modifiers that may be used are described in U.S. patents 5,157,088,
5,256,752 and 5,395,539. The VMs and/or DVMs may be used in the functional fluid
at a concentration of up to 20% by weight. Concentrations of 1 to 12%, or 3 to 10%
by weight may be used.
[0083] Another component may be an antioxidant. Antioxidants encompass
phenolic antioxidants, which may be hindered phenolic antioxidants, onr or both
orthopositions on a phenolic ring being occupied by bulky groups such as t-butyl.
The para position may also be occupied by a hydrocarbyl group or a group bridging
two aromatic rings. In certain embodiments the para position is occupied by an estercontaining
group, such as, for example, an antioxidant of the formula
t-alkyl
t-alkyl
wherein R is a hydrocarbyl group such as an alkyl group containing, e.g., 1 to 18 or
2 to 12 or 2 to 8 or 2 to 6 carbon atoms; and t-alkyl can be t-butyl. Such antioxidants
are described in greater detail in U.S. Patent 6,559,105.
[0084] Antioxidants also include aromatic amines. In one embodiment, an aro
matic amine antioxidant can comprise an alkylated diphenylamine such as nonylated
diphenylamine or a mixture of a di-nonylated and a mono-nonylated diphenylamine.
Other amine antioxidants include phenylnaphthylamine and alkylated phenylnaphthyl
amines.
[0085] Antioxidants also include sulfurized olefins such as mono- or disulfides or
mixtures thereof, for instance, sulfurized diisobutylene, or sulfurized a-olefms. These
materials generally have sulfide linkages of 1 to 10 sulfur atoms, e.g., 1 to 4, or 1 or
2. Materials which can be sulfurized to form the sulfurized organic compositions of
the present invention include oils, fatty acids and esters, olefins and polyolefins made
thereof, terpenes, or Diels- Alder adducts. Details of methods of preparing some such
sulfurized materials can be found in U.S. Pat. Nos. 3,471,404 and 4,191,659.
[0086] Molybdenum compounds can also serve as antioxidants, and these materi
als can also serve in various other functions, such as antiwear agents or friction
modifiers. U.S. Pat. No. 4,285,822 discloses lubricating oil compositions containing a
molybdenum- and sulfur-containing composition prepared by combining a polar
solvent, an acidic molybdenum compound and an oil-soluble basic nitrogen com
pound to form a molybdenum-containing complex and contacting the complex with
carbon disulfide to form the molybdenum- and sulfur-containing composition. Molybdenum
dithiocarbamates and other molybdenum compounds are commercially
available. Additionally, titanium compounds such as titanium alkoxides such as
titanium 2-ethylhexoxide, or titanium carboxylates such as the neodecanoate can
provide a variety of benefits, including antioxidancy and antiwear performance.
[0087] Dithiocarbamates may also serve as antioxidants.
[0088] Typical amounts of antioxidants will, of course, depend on the specific
antioxidant and its individual effectiveness, but illustrative total amounts can be 0.01
to 5 percent by weight or 0.15 to 4.5 percent or 0.2 to 4 percent or 0.5 to 2 percent or
0.05 to 0.1 percent.
[0089] Another additive is an antiwear agent. Examples of anti-wear agents
include phosphorus-containing antiwear/extreme pressure agents such as metal
thiophosphates, phosphoric acid esters and salts thereof, phosphorus-containing
carboxylic acids, esters, ethers, and amides; and phosphites. In certain embodiments a
phosphorus antiwear agent may be present in an amount to deliver 0.01 to 0.2 or
0.015 to 0.15 or 0.02 to 0.1 or 0.025 to 0.08 percent phosphorus. In some embodi
ments, the antiwear agent may comprise an ashless (non-metal-containing) dithiophosphate.
Often the antiwear agent is a zinc dialkyldithiophosphate (ZDP), as
described above. For a typical ZDP, which may contain 11 percent P (calculated on
an oil free basis), suitable amounts may include 0.09 to 0.82 percent. Nonphosphorus-
containing anti-wear agents include borate esters (including borated
epoxides), dithiocarbamate compounds, molybdenum- containing compounds, and
sulfurized olefins.
[0090] Other materials that may be used as antiwear agents (also referred to as
ashless antiwear agents) include tartrate esters, tartramides, and tartrimides. Exampies
include oleyl tartrimide (the imide formed from oleylamine and tartaric acid) and
oleyl diesters (from, e.g, mixed C12-16 alcohols). Other related materials that may be
useful include esters, amides, and imides of other hydroxy-carboxylic acids in gen
eral, including hydroxy-polycarboxylic acids, for instance, acids such as tartaric acid,
malic acid, citric acid, lactic acid, glycolic acid, hydroxy-propionic acid, hydroxyglutaric
acid, and mixtures thereof. These materials may also impart additional function
ality to a lubricant beyond antiwear performance. These materials are described in
greater detail in US Publication 2006-0079413 and PCT publication
WO2010/077630. Such derivatives of (or compounds derived from) a hydroxycarboxylic
acid, if present, may typically be present in the lubricating composition in
an amount of 0.1 weight % to 5 weight %, or 0.2 weight % to 3 weight %, or greater
than 0.2 weight % to 3 weight %.
[0091] Another component that may be used in the composition used in the
present technology is a friction modifier. Friction modifiers are well known to those
skilled in the art. A list of friction modifiers that may be used is included in U.S.
Patents 4,792,410, 5,395,539, 5,484,543 and 6,660,695. U.S. Patent 5,1 10,488
discloses metal salts of fatty acids and especially zinc salts, useful as friction modifiers.
A list of friction modifiers that may be useful may include:
fatty phosphites borated alkoxylated fatty amines
fatty acid amides metal salts of fatty acids
fatty epoxides sulfurized olefins
borated fatty epoxides fatty imidazolines
fatty amines other than the fatty amines discussed above
condensation products of carboxylic acids and polyalkylene-polyamines
glycerol esters such as glycerol monooleate
metal salts of alkyl salicylates
borated glycerol esters amine salts of alkylphosphoric acids
alkoxylated fatty amines ethoxylated alcohols
oxazolines imidazolines
hydroxyalkyl amides polyhydroxy tertiary amines
dialkyl tartrates molybdenum compounds
and mixtures of two or more thereof. If a lubricant is to be used to lubricate a
device that encompasses a wet (lubricated) clutch, additives may be present which
control the amount of slip between the components of the clutch, that is, provide a
relatively high, stable coefficient of friction between the clutch components, such as
at a friction plate-steel plate interface. Among such materials may be borated dispersants,
certain phosphorus-containing compounds, and certain amide compounds.
Other materials that may be useful in providing such performance may include
branched-alkyl calcium sulfonate detergents and calcium alkylphenate detergents.
[0092] Other additives that may optionally be used in lubricating oils include one
or more of pour point depressing agents, extreme pressure agents, anti-wear agents,
color stabilizers, demulsifiers, rust inhibitors, metal deactivators, and anti-foam
agents.
[0093] Anti-foam agents, also known as foam inhibitors are known in the art and
include but are not limited to organic silicones and non-silicon foam inhibitors. Some
examples of organic silicones include dimethyl silicone and polysiloxanes. Some
examples of non-silicon foam inhibitors include copolymers of ethyl acrylate and 2-
ethylhexylacrylate, copolymers of ethyl acrylate, 2-ethylhexyl acrylate, and vinyl
acetate, polyethers, polyacrylates, and mixtures thereof. In some embodiments the
antifoam agent may be a polyacrylate. Antifoam agents may be present in a lubricant
composition in amounts of 0.001 to 0.012 percent by weight or to 0.004 percent, or
0.001 to 0.003 percent by weight.
[0094] Demulsifiers are known in the art and include but are not limited to
derivatives of propylene oxide, ethylene oxide, polyoxyalkylene alcohols, alkyl
amines, amino alcohols, diamines, or polyamines, reacted sequentially with ethylene
oxide or substituted ethylene oxides or mixtures thereof. Examples of demulsifiers
include polyethylene glycols, polyethylene oxides, polypropylene oxides such as
ethylene oxide-propyelene oxide polymers, and mixtures thereof. In some embodiments
the demulsifier may be a polyether. Demulsifiers may be present in a lubricant
at 0.002 to 0.012 weight percent.
[0095] Pour point depressants are known in the art and include but are not limited
to esters of maleic anhydride-styrene copolymers; polymethacrylates; polyacrylates;
polyacrylamides; condensation products of haloparaffin waxes and aromatic compounds;
vinyl carboxylate polymers; copolymers comprising dialkyl fumarates;
polyalphaolefins, vinyl esters of fatty acids; ethylene-vinyl acetate copolymers; alkyl
phenol formaldehyde condensation resins; alkyl vinyl ethers; and mixtures thereof.
[0096] Rust inhibitors may include hydrocarbyl amine salts of alkylphosphoric
acid, hydrocarbyl amine salts of dialkyldithiophosphoric acid, hydrocarbyl amine
salts of hydrocarbyl aryl sulfonic acids, fatty carboxylic acids or esters thereof
(including alkyl substituted succinic acids and salts, esters, amide, or imides thereof)
, esters of nitrogen-containing carboxylic acids, ammonium sulfonates, imidazolines,
or combinations or mixtures thereof. A rust inhibitor may be present in a lubricant in
an amount of 0.02 to 0.2 percent by weight, or 0.03 to 0.15, or 0.04 to 0.12, or 0.05 to
0.10 percent by weight.
[0097] Metal deactivators may be used to neutralize the catalytic effect of metals
for promoting oxidation in lubricating oils. Suitable metal deactivators include but
are not limited to triazoles, tolyltriazoles, thiadiazoles, and combinations or deriva
tives thereof. Examples include derivatives of benzotriazoles, benzimidazoles, 2-
alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2-(N,N'-dialkyldithiocarbamoyl)
benzothiazoles, 2,5-bis(alkyldithio)-l,3,4-thiadiazoles, 2,5-bis-(N,N'-
dialkyldithiocarbamoyl-l,3,4-thiadiazoles, 2-alkyldithio-5-mercaptothiadaizoles, and
mixtures thereof. A metal deactivator may be present in an amount of 0.001 to 0.1, or
0.1 to 0.04, or 0.15 to 0.03 percent by weight.
[0098] In one embodiment a lubricant further comprises (in addition to the poly
mers disclosed herein) at least one of a detergent, a dispersant, an antioxidant, an
anti-wear agent, a friction modifier, a pour point depressant, a corrosion inhibitor,
and antifoam agent, a demulsifier, a metal deactivator, or a metal salt of a phosphorus
acid; in one embodiment a lubricant composition further comprises an overbased
detergent in an amount of 0.5 to 2.0 weight percent and an ashless dispersant in an
amount of 0.5 to 3 weight percent.
[0099] Method for lubricating. The additives and the lubricant compositions
described above may be used for lubricating a mechanical device, and such lubrica
tion may comprise supplying to the device, or to that part of the device that admits
the lubricant, the lubricant as described herein. Examples of suitable devices may
include internal combustion engines such spark-ignited engines, passenger car
engines, or motorcycle engines; gears, clutches, transmissions, hydraulic devices, and
turbines. The lubricant may be a liquid lubricant or a grease.
[0100] Engines may include internal combustion engines such as a gasoline or
spark-ignited engine such as a passenger car engine, a diesel or compression-ignited
engine such as a passenger car diesel engine, heavy duty diesel truck engine, a natural
gas fueled engine such as a stationary power engine, an alcohol-fueled engine, a mixed
gasoline/alcohol fueled engine, a bio-diesel fueled engine, a hydrogen-fueled engine, a
two-cycle engine, an aviation piston or turbine engine, or a marine or railroad diesel
engine. In one embodiment the internal combustion engine may be a diesel fueled
engine and in another embodiment a gasoline fueled engine or a hydrogen-fueled
engine. The internal combustion engine may be fitted with an emission control system
or a turbocharger. Examples of emission control systems include diesel particulate
filters (DPF), exhaust gas recirculation (EGR), and systems employing selective
catalytic reduction (SCR).
[0101] The engine may also be a motorcycle engine and the lubricant may be
considered a motorcycle lubricant. Lubricants for motorcycles typically provide
lubrication for the engine (a crankcase) as well as a wet clutch. These two devices,
although often lubricated by the same fluid, often have different lubrication require
ments. For example, the lubrication of the engine desirably provides low metal-onmetal
friction, to promote good fuel economy. (Typically, the "metal" referred to is
steel.) However, the friction coefficient for the metal-on-composition interfaces
located within the wet clutch may desirably be relatively high, to assure good engagement
and power transmission. Additionally, motorcycle lubricants will also
lubricate other devices such as gears or bearings, each having their own lubricating
requirement. In one embodiment, the lubricant as described herein may lubricate both
the engine and the wet clutch of a motorcycle.
[0102] Hydraulic fluids may be more generally described as, or may be considered
a species of, industrial fluids, which may include hydraulic fluids, turbine oils,
circulating oils, or combinations thereof. A hydraulic fluid may be considered to a
fluid that transfers force through a device by virtue of its fluid properties. The hy
draulic system may comprise a hydraulic pump such as a piston pump, vane pump,
gear pump, or a combination of these. It may also contain hydraulic motors or hydraulic
pistons used to actuate wheels or tracks for locomotion and/or operation of
implements, such as buckets, diggers, or rams. Mobile hydraulic systems include
those used on wheel loaders, backhoes, excavators, rollers, and farm equipment.
Hydraulic fluids and hydraulic equipment may be used in transportation vehicles
systems, such as hydraulic launch assists or hydraulic braking systems, as well as in
stationary devices. In one embodiment, the hydraulic system may be capable of trans
ferring rotational energy into a stored energy reservoir for later reconversion into
rotational energy. The hydraulic fluid may optionally be zinc free, metal free, or
ashless or may optionally contain any of the aforesaid features.
[0103] As used herein, the term "condensation product" and its cognates (e.g.,
"condensed") is intended to encompass esters, amides, imides and other such materials
that may be prepared by a condensation reaction of an acid or a reactive equiva
lent of an acid (e.g., an acid halide, anhydride, or ester) with an alcohol or amine,
irrespective of whether a condensation reaction is actually performed to lead directly
to the product. Thus, for example, a particular ester may be prepared by a transesterification
reaction rather than directly by a condensation reaction. The resulting product
is still considered a condensation product.
[0104] The amount of each chemical component described is presented exclusive
of any solvent or diluent oil, which may be customarily present in the commercial
material, that is, on an active chemical basis, unless otherwise indicated. However,
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.
[0105] 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 hydro
carbyl 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 substitu
ents, 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 found in paragraphs [0137]
to [0141] of published application US 2010-0197536.
[0106] 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. For instance, metal ions (of, e.g., a detergent) can
migrate to other acidic or anionic sites of other molecules. The products formed
thereby, including the products formed upon employing the 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 the composition
prepared by admixing the components described above.
[0107] The invention herein is useful for application in hydraulic systems and
engines, which may be better understood with reference to the following examples.
EXAMPLES
[0108] Examples 1-5 . Lubricants are prepared in a formulation to have a viscosity
index of about 140 with a variety of ISO grades (represented by kinematic viscosity
at 40 °C, mm /s). The lubricants are prepared from the base oils indicated, and each
formulation contains about 0.85% of a commercial dispersant/inhibitor ("DI") package
which in turn comprises a zinc dialkyldithiophosphate, a phenolic antioxidant, calcium
detergents (alkylsulfonate(s) and phenate(s)), an alkyl-substituted carboxylic anhy
dride, and small amounts of other inhibitor(s) and other conventional materials, as well
as diluent oil. Formulations can be made in various viscosity grades, as illustrated in
Table I :
Table I .
a . Relative amounts, totaling 100% oil; API Groups I or III as indicated.
b. Oil-free amount. As supplied, contains 53% oil. Polymer is a star polymer with 6-
15 arms on average, the arms having a M of about 35,000 to 50,000. The arms are
random copolymers comprising CI0-1 8 alkyl methacrylate monomer(s) and CI -9
alkyl methacrylate monomer(s), linked to a core prepared from an alkylene glycol
dimethacrylate.
c . Oil-free amount. As supplied, contains 87% oil. Polymer is a commercial eth
ylene/propylene copolymer, about 45 percent by weight ethylene monomer units,
having a Mw of about 150,000.
[0109] Examples 6-1 1. Lubricants are prepared targeting an ISO 46 viscosity
grade, using varying amounts and various relative ratios of star polymer and eth
ylene/olefin copolymer. The DI package is the same commercial package that is used
in Examples 1-5. Footnotes a, b, and c from Table I apply.
Table II
[0110] The results illustrate ease of formulation of lubricants of a variety of
viscosity grades with high viscosity index, using varying ratios of the polymers of the
disclosed technology.
[0111] Examples 12 and 13 . Lubricants are prepared with formulations as set
forth in Table III (footnotes a, b, and c from Table I apply):
Table III
[0112] The lubricants are also subjected to the 104c ("Conestoga") pump test, as
described in greater detail in ISO20763, and the results are also reported in Table III.
In this test, a pump cam ring and vanes are weighed before and after the test, and the
weight loss from the ring and vanes is measured. The test length is 250 hours, the
temperature 69 °C, pressure of 14 MPa (140 bar) and 1440 r.p.m. The lubricant
sample size is 70 L with a flow rate of about 25 L/min. The results show that the
material of the disclosed technology provides dramatically reduced wear compared
with a similar formulation using a conventional linear methacrylate copolymer
viscosity modifier.
[0113] Examples 14-17. Formulations are prepared as shown in Table IV, below,
using comb polymers identified as d or e in the footnotes or, for reference, a linear
methacrylate polymer.
Table IV
a . Relative amount, totaling 100% base oil
b. See footnote to Table I
c . See footnote to Table I .
d. Oil free amount; as supplied contains 60%> oil. A comb polymer comprising 5% by
weight C12-15 alkyl methacrylate, 83% by weight C4 methacrylate, and 12% by
weight macromonomer comprising an alkyl methacrylate where the alkyl group is
derived from polybutadiene (hydrogenated) having about 355 carbon atoms. Mw
182,000.
e . Oil free amount; as supplied contains 60% oil. A comb polymer comprising 14%
by weight styrene, 58% by weight C4 alkyl methacrylate, and 28% by weight macromonomer
as listed in footnote d. Mw 140,000.
j . Oil free amount; as in Table III.
[0114] Examples 18 (reference) and 19. Lubricant formulations are prepared as
shown in Table V. (Amount of base oil is given as percentage of the lubricant formu
lation.)
Table V
b. As defined in Table I; except containing 54% oil (amount presented in table on
oil-free basis).
c . Ethylene/propylene copolymer as defined for Table I, except provided here as an
oil-free solid material.
f . A commercial passenger car engine oil dispersant/inhibitor package containing about
1 % Na and Ca overbased detergents, 44% dispersant(s), 9% zinc dialkyldithiophosphates,
17% antioxidants, and 8% alkyl tartrimide, each of the foregoing containing
conventional amounts (if any) of diluent oil, plus further diluent oil and smaller
amounts of other conventional components.
g. A methacrylate copolymer; amount includes about 50% diluent oil
[0115] The lubricants of Ex. 18 (reference) and Ex 19, formulated as SAE OW-20
grade lubricants, are tested by an externally driven engine assembly friction test rig,
measuring torque at speeds from 500 to 2,500 r.p.m. at 88, 60, and 25 °C. The percent
reduction in torque for the candidate fluids is compared to that of a baseline SAE
OW-20 fluid. While both fluids exhibit reduced torque compared to the baseline
lubricant at 60 and 88 °C, the formulation containing the mixture of star polymer and
ethylene-propylene copolymer (Ex. 19) exhibits a greater reduction in torque. Results
at 60 and 88 °C are shown in the following Table Va
Table Va
(Results at 25 °C show little change over the baseline; average torque reduction:
+0.42% for Ref. Ex. 18 and -0.57% for Ex. 19.)
[0116] Examples 20 through 26. Lubricants are prepared and tested as shown
Table VI:
Table VI
Aminic antioxidant 0.3 0.3 0.3 0.3 0.3 0.3 0.3
Pour point depressant 0.2 0.2 0.2 0.2 0.2 0.2 0.2
Star polymer b, % 1.3 1.2 0.99 0.61 0.47 0.24 0
Ethylene/olefin copolymer , % 0.60 0.63 0.70 0.81 0.84 0.90 0.98
Viscosity properties:
KV @ 40 °C (mm¾) 90.7 90.2 91.6 94.5 95.7 96.6 97.0
KV @ 100 °C (mm /s) 14.7 14.6 14.6 14.8 14.8 14.7 14.7
Viscosity Index (VI) 170 169 167 163 161 159 158
MRV viscometry, -30°C, Pa-s 17.4 18.0 18.5 19.8 19.9 21.4 22.8
(ASTM D4684)
After-Shear KV@ 100 °C 13.6 13.4 13.5 13.2 13.2 13.2 13.1
(ASTM D7109)
b. As in Table I, oil-free amount
c . As in Table I, oil-free amount
g. As in Table V
h. Including about 33% diluent oil. A borated dispersant, in addition to dispers
present in the DI package.
m. A multipurpose commercial additive package containing 21% overbased deter
gents), 54% dispersant(s), 12%> antioxidants, and 10%> zinc dialkyldithiophosphate,
each of the foregoing containing conventional amounts (if any) of diluent oil, plus
further diluent oil and smaller amounts of other conventional components.
[0117] Lubricants which contain the mixture of Star polymer and olefin copoly
mer exhibit reduced MRV viscosity and increased viscosity index with good retention
of viscosity after shear as measured according to ASTM D7109 (90-pass "Orbahn"
shear stability test, in which polymer-containing fluid is passed through a Bosch™
diesel injector nozzle at high pressure. This treatment causes degradation of polymer
molecules. Kinematic viscosity at 100°C before and after shear is determined).
[0118] Each of the documents referred to above is incorporated herein by refer
ence, including any prior applications, whether or not specifically listed above, from
which priority is claimed. The mention of any document is not an admission that such
document qualifies as prior art or constitutes the general knowledge of the skilled
person in any jurisdiction. 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 optionally modified by the word "about." 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 can be used together with ranges or amounts for any of the other elements.
[0119] As used herein, the transitional term "comprising," which is synonymous
with "including," "containing," or "characterized by," is inclusive or open-ended and
does not exclude additional, un-recited elements or method steps. However, in each
recitation of "comprising" herein, it is intended that the term also encompass, as
alternative embodiments, the phrases "consisting essentially of and "consisting of,"
where "consisting of excludes any element or step not specified and "consisting
essentially of permits the inclusion of additional un-recited elements or steps that do
not materially affect the essential or basic and novel characteristics of the composition
or method under consideration. The expression "consisting of or "consisting
essentially of," when applied to an element of a claim, is intended to restrict all species
of the type represented by that element, notwithstanding the presence of the term
"comprising" elsewhere in the claim.
[0120] While certain representative embodiments and details have been shown for
the purpose of illustrating the subject invention, it will be apparent to those skilled in
this art that various changes and modifications can be made therein without departing
from the scope of the subject invention. In this regard, the scope of the invention is to
be limited only by the following claims. In certain jurisdictions, recitation of one or
more of narrower values for a numerical range or recitation of a narrower selection of
elements from a broader list means that such recitations represent preferred embodi
ments.

What is claimed is:
1. A lubricant composition comprising:
(a) an oil of lubricating viscosity;
(b) a (meth)acrylate-containing polymer comprising a multiplicity of arms
wherein the arms contain at least about 20, or at least 50 or 100 or 200 or 350 or 500
or 1000, carbon atoms, said arms being attached to a multivalent organic moiety; and
(c) an ethylene/olefin copolymer having a weight average molecular weight of
about 5000 to about 250,000, or about 10,000 to about 250,000, wherein the copolymer
comprises about 40 to about 70 weight percent polymerized ethylene monomer
and further comprises one or more polymerized olefin monomers of 3 to 6 carbon
atoms.
2. The lubricant composition of claim 1 wherein said arms are polymeric entities
comprising non-olefinic monomer units.
3. The lubricant composition of claim 1 or claim 2 wherein said arms are poly
meric entities comprising alkyl (meth)acrylate monomer units.
4. The lubricant composition of any of claims 1 through 3 wherein said arms are
polymeric entities comprising comonomers of C10-C18 alkyl methacrylate groups
and C1-C9 alkyl methacrylate groups.
5. The lubricant composition of any of claims 1 through 4 wherein the arms
comprise random copolymers.
6. The lubricant composition of any of claims 1 through 5 wherein the arms
comprise block copolymers.
7. The lubricant composition of any of claims 1 through 6 wherein the number of
arms attached to the multivalent organic moiety is 3 to 20, or 5 to 20, or 6 to 15, or 7 to 8.
8. The lubricant composition of any of claims 1 through 7 wherein the number
average molecular weight of the arms is about 10,000 to about 200,000, or 20,000 to
100,000, or 35,000 to 50,000 .
9. The lubricant composition of any of claims 1 through 8 wherein one or more
of the arms comprises a unit derived from an alkyl acrylate monomer.
10. The lubricant composition of any of claims 1 through 9 wherein the (meth)-
acrylate-containing polymer comprises a star polymer with multiple arms linked to a
core.
11. The lubricant composition of claim 10 wherein the core comprises polymerized
monomers of an alkylene glycol dimethacrylate.
12. The lubricant composition of claim 1 wherein said arms comprise hydrocarbyl
groups.
13. The lubricant composition of any of claims 1 through 1 wherein the
(meth)acrylate-containing polymer comprises a comb polymer.
14. The lubricant composition of claim 13 wherein said arms are polymeric
entities comprising conjugated diene monomer units (optionally hydro genated) or
isobutylene monomer units.
15. The lubricant composition of claim 14 wherein the conjugated diene compris
es butadiene or isoprene.
16. The lubricant composition of any of claims 1 through 15 wherein the amount
of the (meth)acrylate-containing polymer comprising a multiplicity of arms is present
in an amount of about 0.1 to 2.5 or 0.25 to about 2.5 percent by weight.
17. The lubricant composition of any of claims 1 through 16 wherein the ethyl
ene/olefin copolymer comprises at least one of propylene or butylene monomer units.
18. The lubricant composition of any of claims 1 through 1 wherein the ethyl
ene/olefin copolymer comprises propylene monomer units.
19. The lubricant composition of any of claims 1 through 18 wherein the eth
ylene/olefin copolymer comprises about 40 to about 50 percent by weight ethylene
monomer units and about 50 to about 60 percent by weight propylene monomer units.
20. The lubricant composition of any of claims 1 through 19 wherein the eth
ylene/olefin copolymer has a weight average molecular weight of about 20,000 to about
180,000.
21. The lubricant composition of any of claims 1 through 20 wherein the amount
of the ethylene/olefin copolymer is about 0.1 to about 10 or about 0.1 to about 2.5 or
about 0.1 to about 1 percent by weight.
22. The lubricant composition of any of claims 1 through 2 1 further comprising at
least one of a detergent, a dispersant, an antioxidant, an anti-wear agent, a friction
modifier, a pour point depressant, a corrosion inhibitor, and antifoam agent, a demulsifier,
a metal deactivator, or a metal salt of a phosphorus acid.
23. The lubricant composition of any of claims 1 through 22 wherein the composi
tion further comprises an overbased detergent in an amount of about 0.5 to about 2.0
weight percent and an ashless dispersant in an amount of about 0.5 to about 3 weight
percent.
24. A lubricant composition of any one of claims 1 through 23 suitable for lubri
cating a motorcycle crankcase and wet clutch, further comprising an overbased
calcium detergent in an amount of 0.2 to 1.8 weight percent of the composition, an
ashless dispersant in an amount of 0.8 to 3.2 weight percent of the composition, and a
friction modifying additive that increases static friction at a friction plate-steel plate
interface in an amount of 0.05 to 1.85 weight percent of the composition.
25. A method for lubricating a mechanical device comprising supplying thereto
the lubricant composition of any of claims 1 through 24.
26. The method of claim 25 wherein the mechanical device comprises a hydraulic
system.
27. The method of claim 25 wherein the mechanical device comprises an internal
combustion engine.
28. The method of claim 27 wherein the internal combustion engine is a passenger
car engine.
29. The method of claim 27 or claim 28 wherein the internal combustion engine is
a spark-ignited engine.
30. The method of claim 27 wherein the internal combustion engine comprises a
motorcycle engine.