Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
7~7
LUBRICATING OIL COMPOSITIONS
The invention relates to lubricatin~ oil compositions
comprising a hydrocracked lubricating oil as a base oil
and a mixture of certain oil-soluble polyalkyl(rneth)-
acrylates as pour point depressants.
Hydrocracked lubricating oils such as the oils des-
cribed in Netherlands patent application 7613854 can be
obtained with a very high viscosity index (V.I.) and are
therefore particularly suitable as base oils for multi-
grade engine oil formulations, especially multigrade
gasoline and diesel engine oils.
However, for hydrocracked base oils of the extra high
V.I. type (XHVI oils having a VI of at least 140 (ASTM
D-2270)) it appeared not possible to reduce the pour
point which normally is e.gO about -15C to -33C
(ASTM D-97) or lower as required by the current demands
for e.g. cold climates, even not when using pour point
depressants especially designed for use in HVI oils,
including hydrocracked HVI oils, such as the polyalkyl-
~'
l.
methacryla~es described in ~ritish patent 1,347,713.These p~yalky~ethacrylates ha~e an average number molecular
weight of between 2x103 and 1o6, an average ~umber of carbon
atoms in ~he alkyl chains containing 9-18 carbon atoms
of 12.4 to 13.7 and at least 6 alkyl chainls with a different
number Qf carbon atoms among the alkyl chains containing
9-18 carbon atoms. It has now been found that this problem
can be solved by using a special combination of two
classes of polyalkyl(meth)acrylates.
Thus the invention relates to a lubricating oil
composition comprising a hydrocracked lubricating oil as
a base oil and
a) 0.001-20 %w of an oil-soluble polyalkyl(meth)acrylate
with VI improving properties, more than 75 %w of the alkyl
chains having 12-15 C-atoms, the weight average molecular
weight being 103-106, and
b) 0.001-5 %w of an oil-soluble polyalkyl(meth)acrylate
with pour point depressing properties, at most 75 %w of
the alkyl chains having 12-15 C-atoms and 10-90 %w of the
alkyl chains having at least 16 carbon atoms, weight average
molecular weight being 103-105.
US patent 2,655,479 already dlscloses that a syner-
gistic pour point depressing effect can be obtained if a
mixture of two classes of polyalkylmethacrylates is used.
This mixture prlncipally contains polyalkylmethacrylates
with alkyl chains containing 8-18 C-atoms, the average
alkyl chain length being about 12.7 and about 13.5, res-
5~7
pectively, for the two classes of polymers. This patentis directed to solvent extracted(conventional) oils and
nothing is said about the present problem of depressing
thepour~oint of a hydrocracked lubricating oil (unconven-
tional oil).
The lubricating base oil can be a hydrocracked base
oil as described in Netherlands patent application 7~13854
including the XHVI oils, the present invention is particular-
ly concerned with. It preferably has a VI of at least 120,
more preferably at least 1400
These base oils may be blended with other oils, such
as solvent extracted lubricating oils, animal or vegetable
oils, synthetic oils, such as polyolefins, ester oils or
polyoxyalkylene oils, or with residual fractions, such as
bright stock, or with hydrotreated fractions, such as hydro-
treated extracts of distillates or residues.
Additives (a) can act as a VI-improver and if no other
VI improver is present aproportion of 1-10 %w is preferredO
If another VI improver is used normally 0.05-1 %w of
additive (a) is sufficient to obtain the synergistic pour
point depressant effect with additive (b).
The alkyl chains containing 12-15 carbon atoms are
preferably derived from a mixture of branched and un-
branched synthetic alcohols, obtained by hydroformylation,
in particular by reacting a mixture of olefins containing
11-14 carbon atoms, with carbon monoxide and hydrogen in
~7S~l~
the presence of cL complex catalyst consisting of cobalt,
carbon monoxide and a phosphorous compound. Normally the
latter alcohols contain 5-25 %w branched alkyl chains.
In additives (a) at most 25 %w of the alkyl(meth)acrylates
may be derived from other alcohols, in particular
primary alcohols~ such as synthetic (unbranched and
branched, e.g. 5-25 %w branched) C9 11 alcohols, synthetic
or preferably natural (unbranched) C16 18-alcohols, lower
alcohols having 1-8 carbon atoms or alcohols having more
than 18 carbon atoms.
Additives (a) containing in addition to one or more
of the above-mentioned monomers a small amount, e.g. at
most 10 %w, of polar monomers, such as substituted or
unsubstituted vinyl pyridines, substituted or unsubsti-
tuted vinyl pyrrolidones or hydroxyl group-containing
monomers, can also be used.
Additives (a) can have weight average molecular
weights (Mw) of 2x103 to 106, in particular of 5x104 to
5x105. They preferably have a low molecular weight dis
tribution range to provide a good shear stability, which
means that Q - Mw/Mn (Mn = number average molecular
weight) should be low, e.g. 1.5-5, such as 2-4~ If desirable
they may be pre-sheared.
As mentioned above suitable additives (a) have VI
improving properties. Although they can also act as pour
point depressants it will be shown that additives (a) alone
do not sub.stant:ially improve the pour poin~ o~ X~JI oi]s.
Preferred additives (b) are descrlbed in British
patents 1,163,807 and in particular 1,347,713. This means
that the C12_15-alkyl chains are preferably of the type
described above for additives (a), whereas the other alkyl
chains are preferably derived from synthetic Cg 11-
alcohols and/or synthetic or preferably natural C16 18-
alcohols and optionally C1 8-alcohols or alcohols having
more than 18 carbon atoms. The presence of C16 18-
alcohols in proportions of at least 10 %w is particular-
ly desirable. A small amount e.g. at most 10 %w~ of polar
monomers, such as described for additives (a), can also
be present.
Preferred proportions of additive (b) are 0.01-2 %w.
Additives (b) can have weight average molecular
weights (Mw) of 2x103 to 106, in particular 2x104 ~o
5x105. They preferably have a low Q value of e.g. 1.5-5,
such as 2-4.
Additives (a) and (b) can be added, as such or in the
form of a concentrate of (a) and/or (b) in a canrier oil
to the base oils. The concentrate may e.g. contain 20-75
%w of (a) and/or (b) in e.g. a mineral lubricating oil
as carrier oil.
Other additives can also be used, such as antioxidants,
detergents, other VI improvers, anti corrosion agents,
extreme pressure agents, anti-foaming agents, etc.
The invention is illustrated by the following examples.
The additives according to the invention were tested
in various hydrocracke~ base oils.
Base oil 1: a hydrocracked lubricating oil having a pour
point of -15C and a ~I of 149.
Base oil 2: base oil 1 + commercial gasoline engine oil
additive package.
Base oil 3: 88 %w base oil 1 -~ 12 %w hydrotreated bright
stock (VI of 95) (VI of mixture being 144).
Base oil 4: base oil 3 ~ package of base oil 2.
Base oil 5 : 89 %w base oil 1 ~ 11 %w o~ above hydro-
treated bright stock + commercial diese] engine oil
additive package including a VI improver (a hydro-
genated styrene/isoprene block copolymer).
Additive a1: Poly Cl2-l5-alkylmethacrylate derived from
branched and unbranched (weight ratio 15:85) synthetic
C12 15~alcohols (20 %w C12~ 30 %w C13~ 30 %w C14 and
20 %w C15). Mn = 1.35 x 105; Mw = 5.35 x 105; Q = 4Ø
Additive a2: random copolymer of 92.3 %w C12 15-alkylmeth-
acrylate (see additive a1) and 7.1 %w 2-vinylpyridine.
Mw = 63,000; Mn = 223,000; Q = 2.8.
Additive a3: copolymer of 98-0 %w C12_15-alkYlmethaCrY
(see additive a1)~ 0.9 %w Cg 1l-alkylmethacrylate
b1) and 1.1 %w C16_18-alky1methacrylate
(see additive b1). Mw = 310,000; Mn = 93,700; Q = 3.3.
5 Additive b1: poly Cg 18-alkylmèthacrylate derived from
43.5 %w branched and unbranched (weight ratio 15:85)
synthetic Cg 1l-alcohols (20 %w Cg, 50 %w C10 and
~7~
30 %w Cll), 10.0 %w C12_15-alcohols (see additive
al) and 44.5 %w natural C16/18-al~ohols (30 %w C16
and 58 %w C18).
Mw = 420,000; Mn = 55,000; Q = 7.7.
Additive b2: same composition as additive bl, but:
Mn = 21,200; Mw = 46,500; Q = 2.2.
EXAMPLE 1 (base oil 1)
Table 1 (pour points C)
%w b
%w a 0 0.1 0.2 0.3
o -15 -21 -21/-24
0.1 -15 -24 -24
0.2 -15 -24/-27 -30 -3
o,3 -15 -27 -3
0.4 -15 -30 -33
============_======_=======_====
EXAMPLE II (base oil 2)
Table 2 (pour points C)
%w b
%w a 0 0 1 0.2
0 -15 -21 -24
4.0 -15 -36 -36
====================================================
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_~O _ r r _ ~1 l r
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EXAMPLE IV (base oil 2 )
Table 4 (~our polnts C )
addi- %w %w b2
t ive 0 0 .1 0 . 2
a2 -15 ~21 -?4
4 . o -15 -36
a3 -15 -21 -24
4 . 0 -21 -36 -36
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