[0001] The present invention relates to lubricating compositions, especially automobile
crankcase lubricants, containing low or zero amounts of phosphorus and zinc.
[0002] There is currently a drive to reduce the amounts of phosphorus in lubricants because
of the deleterious effect phosphorus has on catalysts commonly used in catalytic converters
used for emission control. Levels of phosphorus have typically been of the order of
0.1% but there is an increasing need to reduce phosphorus levels to below 0.05 wt
% or remove it altogether. However, zinc dialkyl dithiophosphates (ZDDP) and other
phosphorus containing additives have been widely used as anti-wear and/or anti-oxidant
additives and simply reducing or removing such components results in lubricants with
poor engine performance.
[0003] This invention provides lubricant compositions and concentrates with low or zero
amounts of phosphorus and zinc, and which comprise copper, sulphur, and a bearing
corrosion inhibitor, which compositions have been found to have remarkable engine
performance.
[0004] US-A-2356661 deals with lubricating oils containing 50 to 1000 parts per million
of copper as an oil-soluble organic compound such as copper dialkyl dithiocarbamates
and including phosphorus containing compounds together with from 0.1 to 0.5 wt % of
total sulphur in the oil, sulphur being provided as oil-soluble organic sulphur compounds
such as thiocarbamates.
[0005] US-A-2343756 discloses the addition of copper compounds including phosphorus-containing
copper complexes in conjunction with sulphur compounds, to lubricating oils. Amounts
of from 0.1 to 0.5 wt % of sulphur are disclosed, with amounts in excess of 0.5 wt
% sulphur described as being potentially detrimental. In US-A-2552580, cuprous thiophosphates
are included in lubricant compositions at relatively high levels, which will give
high phosphorus level in the oils. In US-A-3346493, a wide variety of metal-containing
polymeric amine-metal reactants are employed as detergents in lubricant compositions.
In an isolated example, a lubricant is described containing inter alia, a copper salt
of an acylated nitrogen compound, 0.075% phosphorus as a ZDDP reacted with hexene
oxide, and a sulphurized methyl ester of a tall oil acid. Other copper containing
lubricants either contain more phosphorus or no sulphur. US-A-4122033 discloses the
entire group of transition metal compounds as antioxidation stabilizers in conjunction
with amines, selenides, phosphines or phosphites and may be used in various applications
including as additives for lubricants. None of the foregoing documents describe fully
formulated lubricant oils which would be appropriate to meet the requirements for
modern lubricants and none specifically address the reduction of phosphorus levels
while maintaining performance in antiwear, antioxidation and corrosion inhibition.
[0006] EP-A-24146 discloses lubricant compositions containing an ashless dispersant and/or
polymeric viscosity index improver dispersant and copper which may be in the form
of a dithiocarbamate, but requires the presence of from 0.01 to 0.5 wt% zinc and from
0.01 to 0.5 wt % phosphorus. Thiadiazole polysulphides are an optional component.
[0007] US-A-4330420 describes oils with reduced phosphorus content (but only to 0.05%P)
using mixtures of dialkyldiphenylamine and a sulphurized polyolefin to compensate
for reduction in the amount of ZDDP. There is no disclosure of the use of copper or
thiadiazole polysulphides.
[0008] EP-A-89844 describes reaction products of 4,4ʹ-methylene-(2,6-di-t-butyl phenol)
and tri-Sec-C₄₋₁₂ alkyl orthoborate and their use in lubricants to enable the amount
of ZDDP to be reduced to provide from 0.05 to 0.11 wt % P.
[0009] US-A-4490265 describes lubricating oils comprising boron-containing heterocyclic
compounds which may be in the form of a metal salt including a copper salt, thiadiazole
polysulphides, terephthalic acid and as an oxidation inhibitor either a bis(dithiobenzil)
metal derivative where the metal may inter alia be copper or a sulphur-bridged, bis
hindered phenol. The desirability of reducing or eliminating phosphorus is not disclosed
and all the Examples of lubricants contain 0.05 wt% P. US-A-4623474 contains a similar
disclosure. US-A-4627930 also describes boron-containing heterocyclic compounds which
may be in the form of a copper salt and may be sulphurized. Thiadiazole polysulphides
and copper carboxylates are also disclosed. Although the boron-containing heterocyclic
compounds are described as phosphorus-free, there is no disclosure of a fully formulated
oil containing less than 0.05 wt % P. US-A-4629580 contains a similar disclosure.
US-A-4629579 discloses boron and metal-boron derivatives for use as extrement pressure,
anti-wear and friction reducing additives for lubricating oils and compositions including
one containing no ZDDP, but there is disclosure of a composition containing low or
zero amounts of phosphorus, with sulphur and copper.
[0010] Lubricant compositions containing low, or zero amounts of phosphorus, but no copper
are described in WO-A-8604601, WO-A-8604602 and WO-A-8606092.
[0011] The invention seeks to provide lubricants having antiwear, corrosion inhibition and
antioxidant performance appropriate to modern oil requirements with reduced or zero
amounts of zinc and phosphorus and without the need for large amounts and/or expensive
forms of antioxidant.
[0012] The term "modern oil" as used herein in relation to automobile crankcase lubricants
refers to oil which can meet the current requirements for crankcase lubricants in
the major industrial countries. High performance engines, increased lifetime requirements
resulting from longer periods between oil changes and higher operating temperatures
all contribute to the increased performance required from lubricants. This invention
is particularly concerned with automobile lubricants which can meet and exceed the
requirements for the SF API Engine Service Category for service station oils and/or
the CD requirements for the CD/API Engine Service Category for Commercial Oils (Diesel
Engines) established jointly by API, SAE and ASTM.
[0013] In one aspect, this invention provides a lubricant composition comprising a major
amount of a lubricating oil, 5 to 500 parts per million by weight (ppm) of added copper
present in oil-soluble form, one or more added oil-soluble sulphur-containing compounds
such that the composition preferably comprises from greater than 0.5 to 2.0 wt % of
total sulphur, more preferably 0.5 to 1.0 wt % of total sulphur, and an effective
amount of a bearing corrosion inhibitor, the composition containing less than 0.05
wt % phosphorus and less than 0.01 wt% zinc, preferably being substantially phosphorus-free
and zinc-free.
[0014] In particularly preferred embodiments of the invention, the lubricant composition
will also contain one or more ashless dispersants and/or one or more viscosity index
improver dispersants and/or one or more overbased additives which function as antacid
and anti-rust agents, such as overbased calcium or magnesium sulphonates or phenates.
[0015] The use of copper in the invention enables a low phosphorus oil with performance
meeting the requirements for modern oils to be obtained economically and with good
control of oxidation, which in an automobile engine is catalysed by metal accumulated
in the oil by wear or corrosion, with iron being a particular oxidation catalyst.
At unduly low concentrations of copper, the anti-oxidant effect may not be sufficient
for some applications. At unduly high concentrations the ash level of the oil will
be increased and an increased tendency to bearing corrosion may be observed. The amount
of added copper in the compositions will generally be within the range of 10 to 400
ppm, typically 10 to 300 ppm, preferably 10 to 200 ppm, e.g. 60 to 200 ppm.
[0016] The ability of the compositions of the invention comprising low amounts of oil-soluble
copper compounds and very low or zero amounts of phosphorus to provide adequate antioxidant
and antiwear performance for the stringent requirements of modern engine tests is
surprising. Copper is known to act in many situations as an oxidation promoter or
catalyst, and closely related metals, such as cobalt and chromium, are not effective
lubricant anti-oxidants. EP-A-24146 teaches the presence of at least 0.01 wt % of
each of phosphorus and zinc.
[0017] It is also surprising that the copper compound functions effectively in compositions
which may contain zinc and other metal compounds, such as calcium or magnesium overbased
additives, which have an inherent pro-oxidant activity.
[0018] The copper compounds used as anti-oxidants in this invention may be chosen from those
described in EP-A-24146 as suitable for lubricants provided that the copper compounds
are substantially free of phosphorus.
[0019] Thus, the copper may be blended into the oil as the oil soluble copper salt of a
synthetic or natural carboxylic acid. Examples of suitable carboxylic acids include
C₁₀ to C₁₈ fatty acids such as stearic or palmitic acid, unsaturated acids such as
oleic acid, branched carboxylic acids such as naphthenic acids of molecular weight
from 200 to 500, neodecanoic or 2-ethylhexanoic acid and alkyl or alkenyl substituted
dicarboxylic acids such as polyalkene substituted succinic acids, e.g. octadecenyl
succinic acids, dodecenyl succinic acids and polyisobutenyl succinic acids.
[0020] The copper may be blended into the oil as oil-soluble copper dithiocarbamates of
the general formula (RRʹNCSS)
nCu, where n is 1 or 2 and R and Rʹ are the same or different hydrocarbyl radicals
containing 1 to 18, preferably 2 to 12 carbon atoms such as alkyl, alkenyl, aryl,
aralkyl, alkaryl and cycloalkyl radicals. Other copper and sulphur containing compounds
such as copper mercaptides, disulphides and thioxanthates are suitable for use in
the invention. Copper sulphonates, phenates, and acetylacetonates may also be used.
[0021] Alternatively the copper may be introduced in the oil in an oil-insoluble form provided
that in the finished lubricant composition the copper is in the form on an oil-soluble
compound. The term "added copper" is intended to exclude copper present in the oil
as a result of accumulation of copper in the oil during use, e.g. by wear or corrosion
of copper-containing components.
[0022] The lubricant compositions of the invention contain an added oil-soluble sulphur
compound. One preferred class of such sulphur compounds are the dithiocarbamates,
preferably of the formula: (RRʹNCSS)
n M, wherein R, Rʹ and n are as defined hereinbefore and M is a suitable metal such
as molybdenum or (as indicated above) copper or a optionally substituted hydrocarbyl
radical. Preferred dithiocarbamates are dialkyl dithiocarbamates preferably containing
2 to 12 carbon atoms such as diamyl dithiocarbamates.
[0023] Sulphur may also be introduced as a mercaptide particularly the mercaptides of aliphatic
mercaptans (including copper mercaptides as indicated above), sulphurized unsaturated
organic compounds including sulphurized olefins (e.g. US-A-4119549, US-A-4119550,
US-A-4191659 and US-A-4147640), sulphurized Diels-Alder adducts (e.g. US-A-3632566,
US-A-3498915 and US-E-27331) and particularly sulphurized unsaturated alcohols and
esters such as sperm oil substitutes, sulphides including di- and polysulphides, thioethers,
thiophenols, thioxanthates (including copper thioxanthates as indicated above), sulphurized
esters, thioesters, thioamides, thiazoles such as benzothiazoles, and particularly
mercaptobenzothiazoles, and thiadiazoles.
[0024] Mineral lubricating oils contain sulphur, whereas synthetic oils may be sulphur-free,
so that the amount of sulphur added as a sulphur-containing compound varies according
to the basestock and the sulphur contents of other components in the lubricating composition,
more preferably so as to give a sulphur content of greater than 0.5 to 1.0 wt % total
sulphur. The lubricant compositions of the invention advantageously contain from 0.5
to 0.7 wt % total S, and most preferably 0.1 to 0.5 wt % S as added oil-soluble sulphur-containing
compound preferably in the form of a sulphurized ester.
[0025] The bearing corrosion inhibitor is a corrosion inhibitor effective at inhibiting
corrosion effects on bearings such as Cu/Pb bearings, where effects such as copper
staining and high weight loss can be encountered. Such additives have been found to
promote the anti-wear performance of the oil. Preferred bearing corrosion inhibitors
are borate esters such as B(OR)₃, (RO)₂B-O-B(OR)₂ or (ROBO)₃, (RO)₂BOR¹OB(OR)₂ and
mixtures (wherein R is a substituted or unsubstituted alkyl, aryl or aralkyl group
or two groups R together form a substituted or unsubstituted alkylene group and R¹
is a substituted or unsubstituted alkylene group) and these materials may be derived,
for example, from alcohols such as alkoxyalkanols (both short chain alkanols and longer
chain alcohols as in US-A-4440656) and polyetheralkanols; mono-,di- and trihydroxy
alkanls, e.g. 2-ethylhexanol, 2-ethylhexan-1,3-diol, butane-1,2-diol, butane-1,3-diol
glycerol and the acyclic polyols of US-A-2866811; hydroxy esters such as glyceryl
mono-oleate; oxazolines derived for example from oleic acid and tris(hydroxymethyl)-amimomethane;
sulphur-containing alcohols such as may be obtained by reacting epoxides with mercaptans
e.g. t-dodecyl-mercaptoethanol; amino alcohols such as alkanolamines e.g. triethanolamine
and tri-isopropanolamine, hydroxyamines made by reacting a primary amine (e.g. oleylamine)
or secondary amine with ethylene or propylene oxide and the compounds of US-A-4406802.
Preferred alcohols are 2-methylpentan-1,3-diol, butane-1,2-diol, butane-1,3-diol and
similar 1,2 and 1,3 diols, and ethoxyethanol.
[0026] In a preferred aspect the invention contains from 0.01 to 10 wt %, preferably 0.1
to 5 wt %, of a borate ester especially an ester of an alkoxyalkanol or a polyetheralkanol,
e.g. a tris(ethoxyethyl) orthoborate ester or metaborate ester, or a biborate of a
diol such as butane-1,3-diol.
[0027] As an alternative, the bearing corrosion inhibitor is a thiadiazole mercaptan, especially
a thiadiazole polysulphide containing from 5 to 50 carbon atoms, a derivative or polymer
thereof. Preferred materials are the derivatives of 1,3,4 thiadiazole polysulphides
such as those described in US-A-2719125, 2719126 and 3087932. Especially preferred
is the compound 2,5-bis (t-octadithio)-1,3,4-thiadiazole commercially available as
Amoco 150 or 2,5-bis(nonyldithio)-1, 3,4-thiadiazole available as Amoco 158. Other
similar materials also suitable are described in US-A-3821236, 3904537, 4097387, 4107059,
4136043, 4188299 and 4193882. Derivatives of thiadiazole mercaptans may be used such
as esters, condensation products with halogenated carboxylic acids, reaction products
with aldehydes and amines, alcohols or mercaptans, amine salts, dithiocarbamates,
reaction products with ashless dispersants (e.g. US-A-4140643 and US-A-4136043) and
reaction products with sulphur halides and olefins.
[0028] These materials are preferably present in an amount of from 0.01 to 10 wt %, more
preferably 0.1 to 5.0 wt % of the lubricant composition.
[0029] The lubricating compositions may comprise small amounts of phosphorus, less than
0.05 wt %, preferably less than 0.01 wt%, more preferably less than 0.005 wt %, but
more preferably the lubricating compositions are substantially free of phosphorus.
[0030] In a preferred aspect the lubricating composition further comprises:
(A) from 1 to 10 wt % of an ashless dispersant compound which is:
an ashless nitrogen or ester containing dispersant compound preferably selected from:
(i) oil soluble salts, amides, imides, oxazolines and esters, or mixtures thereof,
of long chain hydrocarbon substituted mono and dicarboxylic acids or their anhydrides;
(ii) long chain aliphatic hydrocarbon having a polyamine attached directly thereto;
and
(iii) Mannich condensation products formed by condensing a molar proportion of long
chain hydrocarbon substituted phenol with 1 to 2.5 moles of formaldehyde and 0.5 to
2 moles of polyalkylene polyamine; wherein said long chain hydrocarbon group is a
polymer of a C₂ to C₅ monoolefin, said polymer having a molecular weight of 700 to
5000; and/or
(B) from 0.3 to 10 wt %, of a nitrogen or ester containing polymeric viscosity index
improver dispersant which may include
(a) polymers comprised of C₄ to C₂₄ unsaturated esters of vinyl alcohol or C₃ to C₁₀
unsaturated mono- or di-carboxylic acid with unsaturated nitrogen containing monomers
having 4 to 20 carbons;
(b) polymers of C₂ to C₂₀ olefin with unsaturated C₃ to C₁₀ mono- or di-carboxylic
acid neutralised with amine, hydroxy amine or alcohols; and
(c) polymers of ethylene with a C₃ to C₂₀ olefin further reacted either by grafting
C₄ to C₂₀ unsaturated nitrogen containing monomers thereon or by grafting an unsaturated
acid onto the polymer backbone and then reacting said carboxylic acid groups with
amine, hydroxy amine or alcohol.
[0031] The nitrogen containing dispersant additives are those known in the art as sludge
dispersants for crankcase motor oils, e.g. such as shown in US-A-3275554, US-A-3565804,
US-A-3442808, US-A-3442808, GB-A-983040 or BE-A-658236.
[0032] The most commonly used dispersants are those formed by reacting alkenyl succinic
anhydride, e.g. polyisobutenyl succinic anhydride, and an amine described in US-A-3202678,
3154560, 3172892, 3024195, 3024237, 3219666, 3216936 and BE-A-662875.
[0033] Alternatively the ashless dispersants may be esters derived from long chain hydrocarbon
substituted carboxylic acids and from hydroxy compounds such as monohydric and polyhydric
alcohols or aromatic compounds such as phenols and naphthols as prepared for example
in US-A-3522179.
[0034] Hydroxyamines which can be reacted with any of the aforesaid long chain hydrocarbon
substituted carboxylic acids to form dispersants include 2-amino-1-butanol, 2-amino-2-methyl-1-propanol,
p-(beta-hydroxyethyl)-aniline, 2-amino-1-propanol, 3-amino-1-propanol, 2-amino-2-methyl-1
3-propane-diol, 2-amino-2-ethyl-1, 3-propanediol, N-(beta-hydroxy-propyl)-Nʹ-(beta-aminoethyl)-piperazine,
tris(hydroxmethyl) amino-methane (also known as trismethylolaminomethane), 2-amino-1-butanol,
ethanolamine, beta-(beta-hydroxyethoxy)-ethylamine, and the like. Mixtures of these
or similar amines can also be employed.
[0035] Preferred dispersants are those derived from polyisobutenyl succinic anhydride and
polyethylene amines, e.g. tetraethylene pentamine, polyoxyethylene and polyoxypropylene
amines, e.g. polyoxypropylene diamine, trismethylolaminomethane and pentaerythritol,
and combinations thereof. One particularly preferred dispersant combination involves
a combination of (A) polyisobutenyl succinic anhydride with (B) a hydroxy compound,
e.g. pentaerythritol, (C) a polyoxyalkylene polyamine, e.g. polyoxypropylene diamine,
and (D) a polyalkylene polyamine, e.g. polyethylene diamine and tetraethylene pentamine
using about 0.01 to about 4 equivalents of (B) and (D) and about 0.01 to about 2 equivalents
of (C) per equivalent of (A) as described in US-A-3894763. Another preferred dispersant
combination involves the combination of (A) polyisobutenyl succinic anhydride with
(B) a polyalkylene polyamine, e.g. tetraethylene pentamine, and (C) a polyhydric alcohol
or polyhydroxy-substituted aliphatic primary amine, e.g. pentaerythritol or trismethylolaminomethane
as described in US-A-3632511.
[0036] The alkenyl succinic polyamine type dispersants can be further modified with a boron
compound such as boron oxide, boron halides, boron acids and ester of boron acids
in an amount to provide 0.1 to 10 atomic proportions of boron per mole of the acylated
nitrogen compound as generally taught in US-A-3087936 and 3254025. Mixtures of dispersants
can also be used such as those described in US-A-4113639.
[0037] The oils may contain from 1.0 to 10 wt %, more preferably 2.0 to 7.0 wt % of these
dispersants.
[0038] The dispersancy may be provided by 0.3 to 10% of a polymeric Viscosity Index improver
dispersant, for example copolymers of alkyl methacrylates with N-vinyl pyrrolidone
or dimethylaminoalkyl methacrylate, alkyl fumarate-vinyl acetate N-vinyl pyrolidine
copolymers, post-grafted interpolymers of ethylene-propylene with an active monomer
such as maleic anhydride which may be further reacted with an alcohol or an alkylene
polyamine, such as in US-A-4149984; or styrene/maleic anhydride polymers post-reacted
with alcohols and amines, ethoxylated derivatives of acrylate polymers such as in
US-A-3702300.
[0039] Magnesium and/or calcium containing additives are frequently included in lubricating
compositions either alone or in combination with other alkali metal or alkaline earth
metal additives such as those containing sodium. These may be present for example
as the metal salts of sulphonic acids, alkyl phenols, sulphurised alkyl phenols, alkyl
salicylates, naphthenates, and other oil soluble mono- and di-carboxylic acids.
[0040] Highly basic alkaline earth metal alkaryl sulfonates are generally known for example
in US-A-3150088 and 3150089. For the purposes of this invention, a preferred alkaline
earth sulfonate is magnesium alkyl aromatic sulfonate having a total base number (TBN,
as measured by the procedure of ASTM D2896) ranging from 300 to 400.
[0041] Polyvalent metal alkyl salicylate and naphthenate materials may also be included,
such as the methylene and sulfur bridged materials which are readily derived from
alkyl substituted salicylic or naphthenic acids or mixtures of either or both with
alkyl substituted phenols. Basic sulfurized salicylates and a method for their preparation
are shown in US-A-3595791.
[0042] The sulfurized metal phenates can be considered the "metal salt of a phenol sulfide"
which thus refers to a metal salt, whether neutral or basic, of a compound typified
by the general formula:

where x = 1 or 2, n = 0, 1 or 2
or a polymeric form of such a compound, where R is an alkyl radical, n and x are each
integers from 1 to 4, and the average number of carbon atoms in all of the R groups
is at least about 9 in order to ensure adequate solubility in oil. The individual
R groups may each contain from 5 to 40, preferably 8 to 20, carbon atoms. The metal
salt is prepared by reacting an alkyl phenol sulfide with a sufficient quantity of
metal containing material to impart the desired alkalinity to the sulfurized metal
phenate.
[0043] The sulfurized alkyl phenol is converted by reaction with a metal containing material
including oxides, hydroxides and complexes in an amount sufficient to neutralize said
phenol and, if desired, to overbase the product to a desired alkalinity by procedures
well known in the art. Preferred is a process of neutralization utilizing a solution
of metal in a glycol ether.
[0044] Magnesium and calcium containing additives such as described above although beneficial
in other respects can increase the tendency of the lubricating oil to oxidise. This
is especially true of the highly basic sulphonates.
[0045] According to a preferred embodiment the invention therefore provides a crankcase
lubricating composition also containing from 2 to 8000 parts per million of calcium
and/or magnesium.
[0046] The magnesium and/or calcium is generally present as basic or neutral detergents
such as the sulphonates and phenates, and preferred additives are basic magnesium
or calcium sulphonates. Preferably the oils contain from 500 to 5000 parts per million
of calcium and/or magnesium from such additives.
[0047] These compositions of our invention may as an alternative or in addition contain
other similar metal-containing detergent additives, for example, those containing
barium, sodium, potassium or lithium.
[0048] The lubricating oil used in the lubricant composition may be a mineral lubricating
oil or a synthetic lubricating oil or a mixture thereof. Suitable synthetic oils include
diester oils such as di(2-ethyl-hexyl) sebacate, azelate and adipate; complex ester
oils such as those formed for dicarboxylic acids, glycols and either monobasic acids
or monohydric alcohols; silicone oils; sulfide esters; organic carbonates; hydrocarbon
oils and other synthetic oils known to the art. The invention is particularly useful
in mineral lubricating oils and has the added benefit that it may allow use of base
stock oils that have inferior antioxidant properties to those currently used.
[0049] The lubricating compositions of the present invention may and usually will contain
other traditional lubricant additives provided that they are substantially zinc-free
and phosphorus-free - for example, rust inhibitors such as oleic acid and its derivatives
such as N-oleylsarcosine, and oleic acid dimers and trimers, lecithin, sorbitan mono-oleate,
dodecyl succinic anhydride or ethoxylated alkyl phenols; pour point depressants such
as copolymers of vinyl acetate with fumaric acid esters of coconut oil alcohols; and
viscosity index improvers such as olefin copolymers or polymethacrylates.
[0050] In copper-free oils other antioxidants in addition to the zinc dialkyldithiophosphate
are sometimes required to improve the oxidative stability of the oil. These supplementary
antioxidants are included especially when the basestock has poor oxidative stability;
and typically the supplementary antioxidant is added to the oil in amounts from 0.1-1.5
wt %. The supplementary antioxidants that are used include phenols, hindered-phenols,
bis-phenols, and sulphurised phenols, catechol, alkylated catechols and sulphurised
alkyl catechols, diphenylamine and alkyl diphenylamines and phenyl-1-naphthylamine
and its alkylated derivatives.
[0051] The inclusion of small amounts of copper generally removes the need for these supplementary
antioxidants. It would, however, still be within the scope of our invention for a
supplementary antioxidant to be included especially for oils operating under particularly
severe conditions where the presence of such supplementary antioxidants may be beneficial,
provided that substantially no phosphorus is thereby introduced.
[0052] Additives for lubricating oils are generally supplied as concentrates in oil for
incorporation into the bulk lubricant. The present invention therefore provides concentrates
comprising an oil solution containing:
(1) less than 0.1 wt % of phosphorus and less than 0.1 wt% of zinc;
(2) from 1 to 50 wt % of an oil-soluble sulphur-containing compound;
(3) from 0.005 to 2 wt % of copper; and
(4) from 0.1 to 20 wt % of a bearing corrosion inhibitor,
and optionally a dispersant selected from the group consisting of:
(a) 0 to 60, e.g. 10 to 60 wt % of an ashless dispersant compound,
(b) 0 to 40, e.g. 3 to 40% of a polymeric viscosity index improver dispersant, although
it is usual to add any viscosity index improver separately.
[0053] The concentrate may also contain other additives such as the detergents and viscosity
index improvers previously described. A particularly preferred concentrate also contains
a magnesium and/or calcium containing additive and the invention therefore provides
a concentrate which further comprises from 0.1 to 8 wt % of calcium and/or magnesium.
[0054] The following Examples are now given, though only by way of illustration, to show
certain aspects of the invention in more detail.
Comparative Examples I-VI and Examples 1 and 2
[0055] In the following Comparative Examples and Examples of the invention, formulations
are prepared with the combinations and amounts of additives set out in Table 1, with
the balance being a diluent oil suitable for lubricating compositions and comprising
0.3 wt % sulphur. The additives used are as follows:
A is a dispersant V.I. additive comprising an oil solution containing 21% of a multifunctional
ethylene-propylene copolymer and containing 0.29 wt % N.
B is an ashless dispersant comprising a 50 wt % oil solution of borated polyisobutenyl
succinimide having a polyisobutenyl radical with a molecular weight of approximately
950 and containing 1.6 wt % N and 0.35 wt % B.
C is an oil solution of an overbased magnesium sulphonate having a TBN of 400 and
a magnesium content of 9.2 wt % and a sulphur content of 1.7 wt %.
D is an oil solution of an overbased calcium sulphonate having a TBN of 300 and a
calcium content of 11.9 wt % and a sulphur content of 1.9 wt %
E is an oil solution of copper oleate containing 4 wt % copper.
F is a 30 wt % solution in oil of a hindered methylene bis-phenol antioxidant.
G is an alkylated diphenylamine antioxidant, commercially available as Irganox L-57
from Ciba-Geigy.
H is a 50 wt % oil solution of a zinc diamyl dithiocarbamate containing 6 wt % of
zinc and 12 wt % sulphur.
J is an orthoborate ester made from ethoxyethanol comprising 5 to 6 wt % of boron.
K is 2,5-bis(nonyldithio)-1,3,4-thiadiazole, commercially available as Amoco 158 from
Amoco Chemical Company, comprising 33 wt % sulphur.
L is an oil solution containing 12 wt % of molybdenum as the octoate.
M is a sulphurized ester sperm oil substitute, commercially available as Emery 9844
from Emery Corporation, and comprising 11.5 wt % sulphur.
[0056] The formulations were tested in the following standard tests:
Seq. IIID engine test according to ASTM STP 315M Part II in which the maximum and
average cam plus lifter wear are measured. A pass in this test is achieved with maximum
wear of 0.02 cm (0.008 in.) or better, and an average wear of 0.01 cm (0.004 in.)
or better.
Kinematic viscosity increase in the IIID was measured at 40°C as a percentage increase
in 64 hours. A pass is achieved in this test by achieving a viscosity increase in
64 hours of not more than 375%.
CRC-L-38 Screener engine test based on ASTM STP 509A PE IV in which the bearing weight
loss (BWL) is measured. A pass in this test is achieved with BWL of not more than
40 mg.
[0057] The results are shown in Table 2. These results show the invention provides a surprising
advantage in lubricants which have excellent antioxidant, anti-wear, and bearing corrosion
inhibition with substantial absence of phosphorus and zinc. Comparative Examples I,
II, and III show that in the absence of a bearing corrosion inhibitor, wear performance
was inadequate. Comparative Example IV shows that the addition of a molybdenum additive
did not improve wear performance. Comparative Example V shows that in the absence
of copper antioxidant performance was inadequate even with conventional amounts of
other known antioxidants.
[0058] The Examples of the invention show that the performance of the formulations is not
merely summation of the performance of individual additive, but gives a surprising
improvement in antiwear, antioxidant and bearing corrosion performance, while having
phosphorus levels below those commercially employed in conventional oils.

Concentrates - Typical concentrates for providing the above formulations.
[0059]

[0060] Concentrates may also contain some dilute oil to improve handling (reduce viscosity).
1. A crankcase lubricant composition for use in automobile engines comprising a major
amount of a lubricating oil, 5 to 500 parts per million by weight (ppm) of added copper
present in oil-soluble form, one or more added oil-soluble sulphur-containing compounds
such that the composition comprises from greater than 0.5 to 2.0 wt % of total sulphur
and an effective amount of a bearing corrosion inhibitor, the composition containing
less than 0.05 wt % phosphorus and less than 0.01 wt% zinc.
2. A composition as claimed in claim 1, in which the amount of added copper in the
composition is from 10 to 400 ppm.
3. A composition as claimed in claim 2, in which the amount of added copper in the
composition is from 10 to 200 ppm.
4. A composition as claimed in claim 3, in which the amount of added copper in the
composition is from 60 to 200 ppm.
5. A composition as claimed in any of the preceeding claims, in which copper may be
blended into the oil as the copper salt of a C₁₀ to C₁₈ fatty acid, an unsaturated
carboxylic acid, a naphthenic acid of molecular weight from 200 to 500 or an alkyl
or alkenyl substituted dicarboxylic acid, an oil-soluble copper dithiocarbamates of
the general formula (RRʹNCSS)nCu, where n is 1 or 2 and R and Rʹ are the same or different hydrocarbyl radicals
containing 1 to 18 carbon atoms, a copper sulphonate, a copper phenate, or a copper
acetylacetonate.
6. A composition as claimed in any of the preceding claims, in which the oil-soluble
sulphur compound is a dithiocarbamate of the formula: (RRʹNCSS)n M (wherein R, Rʹ and n are as defined in claim 5 and M is a suitable metal) or a
mercaptide, a sulphurized unsaturated organic compound, a sulphide, a thioether, a
thiophenol, a thioxanthate, a sulphurized ester, a thioester, a thioamide, a thiazole
or a thiadiazole.
7. A composition as claimed in claim 6, in which the oil-soluble sulphur compound
is a dialkyl dithiocarbamate containing 2 to 12 carbon atoms.
8. A composition as claimed in any of the preceding claims, which contains from greater
than 0.5 to 1.0 wt % total S, including from 0.1 to 0.5 wt % S as added oil-soluble
sulphur-containing compound.
9. A composition as claimed in any of the preceding claims, which is substantially
zinc-free.
10. A composition as claimed in claim 6 which contains from 0.5 to 3 wt % sulphurized
ester.
11. A composition as claimed in any of the preceding claims, in which the bearing
corrosion inhibitor comprises one or more borate esters of the formula:
B(OR)₃ or (RO)₂B-O-B(OR)₂, (ROBO)₃ or (RO)₂BO-R¹-OB(OR)₂
(wherein R is a substituted or unsubstituted alkyl, aryl or aralkyl group or two groups
R together form a substituted or unsubstituted alkylene group and R¹ is a substituted
or unsubstituted alkylene group) and/or a thiadiazole polysulphide containing from
5 to 50 carbon atoms, a derivative or polymer thereof.
12. A composition as claimed in claim 11, which contains from 0.01 to 10 wt % of a
borate ester.
13. A composition as claimed in claim 11 or claim 12, in which the borate ester is
a tris(ethoxyethyl) orthoborate ester or a biborate of butane-1,3-diol.
14. A composition as claimed in claim 11 which contains from 0.01 to 10 wt % of 2,5-bis(t-nonyldithio)-1,
3,4-thiadiazole.
15. A composition as claimed in any of the preceding claims, which contains less than
0.005 wt % of phosphorus.
16. A composition as claimed in claim 15 which is substantially free of phosphorus.
17. A composition as claimed in any of the preceding claims, which further comprises:
(A) from 1 to 10 wt % of an ashless dispersant compound and/or
(B) from 0.3 to 10 wt %, of a nitrogen or ester containing polymeric viscosity index
improver dispersant.
18. A composition as claimed in any of the preceding claims, which comprises from
2 to 8000 parts per million of calcium and/or magnesium.
19. A composition as claimed in claim 18, which comprises from 500 to 5000 parts per
million of calcium and/or magnesium as a basic calcium and/or magnesium sulphonate.
20. A composition as claimed in any of the preceding claims, which further comprises
one or more of rust inhibitors, pour point depressants, additional anti-oxidants and
viscosity index improvers.
21. A concentrate comprising an oil solution containing:
(1) less than 0.1 wt % of phosphorus; and less than 0.1 wt % of zinc;
(2) from 1 to 50 wt % of an oil-soluble sulphur-containing compound;
(3) from 0.005 to 2 wt % of copper;
(4) from 0.1 to 20 wt % of a bearing corrosion inhibitor; and
(5) from 0 to 60 wt % of an ashless dispersant and/or from 0 to 40 wt % of a polymeric
viscosity index improver dispersant.
22. A concentrate as claimed in claim 21, which further comprises from 0.01 to 8 wt
% of calcium and/or magnesium.
23. The use of oil-soluble copper as antioxidant in a zinc-free and phosphorus-free
lubricant composition comprising an oil-soluble sulphur-containing compound, a bearing
corrosion inhibitor, and ashless dispersant and/or a polymeric viscosity index improver
dispersant, and a calcium and/or magnesium containing detergent.
24. The use in a crankcase lubricant composition for automobile engines which contains
less than 0.05 wt % phosphorus and less than 0.01 wt % zinc, of 5 to 500 ppm of added
copper present in an oil-soluble form, from greater than 0.5 to 2.0 wt % of total
sulphur, and a bearing corrosion inhibitor to control oxidation, wear and corrosion
and meet at least the quality standard of category SF and/or CD of the API Engine
Service Categories.