Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
37~2
-- 2 --
The ne~er engines place increa~ed demands on the lubrioants
to be emp]oyed. In the pa~t a number of different additi~e~ ha~e
been added to lubricatin~ oils to improve su¢h properties as
viscositg index and dispersancy. One such additive added to
lubrioating oils to improve ~i~oosity index i8 a two-block
oopolymer having the general configuration A-~ where A is
styrene and B is hydrogenated isopreno. See generally U.S.
Patent No~. 3,763,o44 and 3,772,196. A VI improv~r having
¦ greatly improved meohanical ~hear stability is~he 8~ eotively
hydrogenated ~tar-ahaped polymer di~closed in ~$~YflnA~h Patent
Application ~68. Significant reductions in oo~t can be made
by employing a ~ingle additive that improves a number of lubricant
properties. ~owever, in attempting to improve more than a single
lubrioant property, oare muet be taken in~not causing the
~15 deterioration of other properties. For example, by employing
an oxidation step to attach polar groups~to the polymer baok-
bone in U.S. 3,864,2689 the~patentees~ha~e reduoed lubrioant ~
stability by introducing cite~for oxidative attack. ; ~ -
Ashleas, oil-~oluble additive~ having both disper~ant and ~ ;
visoosity-index (YI) improving~properties are prepared by the
prooe~s oomprising~
(a) reaoting a ~electi~ely~!hydrogènated star-shaped polymer
with an alpha-beta unsaturated oarboxylio aoid, anhydride
or e~ter preferably at a temperature of between about 150C `~
25 ~ and about 300C, for~between about 1 hour and about~24 hour~
wherein said etar-shaped polymer compri~e~ a~poly (polyalkenyl
coupling~agent) nuoi~eu6, and at~least 4 polymerio arms~ -
e~B. 4-25 armB~ whioh~arms eaoh san have a~number average
molecular weight of~e.g. about~S,OOO to~about 150~000 and
whioh are linked~to~said nuoleus wherein ~aid polymeric
arms are seleoted~from the group oon~isting of:
(i) hydrogenated homopolymers and hydrogenated
oopolymers of;o~on~ugated;dienes;
hydrogenat~ed oopolymers of conjugated dienea
~5 ~ ~ ~and =onoalkrnyl arenes: and ?
3 --
(iii) mixture~ thereof;
and wherein at least about 80%, preferably about 90 to
about 98%, of the alphatio unsaturation of the ~tar-
shaped polymer ha~ been reduced by hydrogenation while
les~ than 20% of the aromatic un~3aturation ha~ been
reducede and
(b) reacting the product of step (a) with a C1 to C18 amlne
oontaining 1 to 8 nitrogen atoms and/or with an alkane polyol
having at least two hydroxy groups preferably at a temperature
of between about 150C and about 250C.
In an alternative embodiment, the reaction between the star-
shaped polymer and the oarboxylic aoid or derivative takes place
after the ohlorination of the polymer or in the presence of
chlorine, as more fully explained below.
~he di~persant VI improvers of the present invention pos~ess
excellent viscosity improving properties, o~idative stability,
mechanical shear stability, and dispersancy. In particular, the
lubricating oil~ containing the instant VI impro~er/dispersant~
possess excellent thickenin~ efficiency at high temperature~while
also possessing very good low temperature viscosity characteri~tics.
; Importantly, by employing~the instant VI improverldispersants, a~
opposed to the prior art rI improvers, a lower amount of polymer
is required in order to obtain the required thickenin~ performance.
Further, the instant polymers not onl~ possesæ much superior
oxidative shear ~tability and permanent ahear ~tability, they also
; posseæs significantly improved "te~porary shear 1088". Temporary
shear 1088 refers to the temporary viscosity 1088 at high shear
~; stress conditions resulting fro~ the non-~ewtonian character of
the polymeric VI improvers. Still further, the di~persin~ power
of the instant polymeric additive i8 excellent. ~hi~ combination
of desirable propertiés has ne~er before been obtainable in a
~ingle additive.
1) Preparation of tbe Base Polymer - ~he ba~e pol~mer
employed in makin~ the preæent disper~ant VI improvers is a
35~ star polymer. These poIycers are generally produced by the
.
~''
'
,.:
'7~
process oomprising the following reaction ~t0ps:
(a) polymerizing one or more con~ugated diene~ and,
optionally, one or more monoalkenyl arene oompound~, in
solution, in the pre~en¢e of an ionic initiator to form a
living polymer;
(b) reacting the living polymer with a polyalkenyl ¢oupling
sgent ~uoh a~ a polyvinyl aromatic compound, pref~rably
divinyl benzene to form a star-shaped polymer and
(c) hydrogenating the star-ahaped polymer to form a
hydrogenated star-shaped polymer.
The living polymer0 produced in reaction ~tep (a) of the present
proce~s are the precursors of the hydrogenated polymer chain~
which extend outwardly from the poly(polyalkenyl coupling agent)
nucleus . ~o 0
his preparation i~ de~cribed in detail in ~e~ *fl~ patent
iI application ~Teet~8. Preferably each polymeric arm i~ a hydrogenated
polyisoprene homopolymer.
The molecular weights Or the ~tar-shaped polymer to be
hydrogenated in reaction step (c) may vary between relati~ely
wide limits. ~owever, an important aspe¢t of the present invention
i8 that polymers po~ses~ing good shear stability may be produced
e~en though the polymers have very high molecular wei~ht~. It is
possible to produce star polymers ha~ing peak moleoular weight~
between about 25,000 and about 1,250,000. Preferred molecular
we~ghts are 100,000 to 500,000. ~he~e peak molecular weight~ are
determined by gel permeation chromatography (GPC) on a poly~tyrene
scale.
In step (c), the star haped polymers are hydrogenated by
any suitable technique. Suitably at least 80~, preferably about
90 to about 98% of the original olefinio unsaturation i8
hydrogenated. If the star-shaped polymer is partly derived from a
monoalkenyl arene compound, then the amount of aromatic unsaturation
which i8 hydrogenatedp if any, will depend on the hydrogenation
conditions used. ~owever, preferably les~ than 20%, more preferably
less than 5% of such aromatic unsaturation is hydrogenated. If the
.. , . ; ~ .
'7
- 5 -
poly(polyalkenyl coupling agent) nucleus is a poly(polyalkenyl
aromatic coupling agent) nuoleu~, then the aromatlc un~aturation
of the nucleu~ may or may not be hydrogenated again depending
upon the hydrQgenation conditions used. The molecular wei~hts
of the hydro~enated ~tar-shaped polymers c:orrespond to tho~e
of the unhydrogenated ~tar-shaped polymer~.
~ he hydrogenation can be carried out aa de~oribed in
~O~ , o 7 ~7 ~o~ o'7'7
~othcrlnndo patent application ~e~6~.
A much preferred hydrogenation proceEIs i~ the s~lective
hydrogenation proces~ shown in ~.S. 3,595,942. In that prooe~s
hydrogenation is conducted, preferably in the same solvent in
which the polymer was prepared,utilizing a catalyst compri~ing
the reaction product of an alumi~umalkyl and a nickel or cobalt -
carboxylate or alkoxide. A favoured catalyst i~ the reaction
product formed from triethyl aluminiu~ and nickel octoate.
~ he hydro~enated ~tar-~haped polymer iB then recovered in
solid form from the solvent in which it is hydro~enated by any
convenient technique such as by evaporation of the ~olvent.
Alternatively, an oil, e.g. a lubricating oil, may be added to
the ~olution and the solvent ~tripped of~ from the mixture ~o
formed to produce concentrate~ Easily handleable concentrates
are produced even when the amount of hydrogenated star-shaped
polymer therein exceeds 10%w. Suitable concentrate~ contain
from 10 to 25%w of the hydrogenated star-~haped polymer.
2) ~ - ~he
selectively hydrogenated star polymers as prepared above do not
have sdequate dispersancy characteristics by themselves. ~hererore,
the base polymer must be derivatized as explalned below.
~he star polymer is fir~t reacted with an un~aturated carbo~y~
lio acid or dexivative thereof. By "derivative thereof" i~ meant
anhydrides, esters and the like. Suitable unsaturated acids and
derivatives include maleic acid, maleic anhydride, itaconic acid,
dimethyl itaconate, aorylio aoid, ethyl aorylate, methyl methaorylate,
oleic acid, linoleic acid, etc. The preferred acidic compounds are
those containing alpha--beta unsaturation. Maleic anhydride is
.
espeoially preferred.
The oarboxylic compound and th~ ~tar polymer are reaoted
together e.g. at a temperature of bstween about 150C and about
300C, preferably between about 180C and about 250C. The
contaoting time is e.~. between about 1 hour and about 24 hour~,
preferably between about 4 hour~ and about 12 hour~ The carboxyllc
compound rea¢t~ with the re~idual olefinic bond~ available on
the diene portion of the polymer. When the carboxyli¢ compound
employed i8 maleic anhydride, u~ually about 10~ to 100%,
preferably 50~ to 95% of the re~idual double bonds in the
polymer are oonverted to ~ucoinic anhydride group~.
Various solvents may be employed in the carboxylic aoid
derivative addition step including generally olefin-free petroleum
hydrocarbons, aromatics and halogenated hydrocarbon~. A pr~erred
solvent is a lubricating oil basestocX. A much-preferred ~olvent
i8 trichlorobenzene~ Preferably, a concentration in the range of
about 1% to about 10% by wei~ht of the copolymer in ~olvent may
conveniently be used for thi~ conver~ion.
An excess of carboxylic compound over that stoichiometrically
necessary to react with all the recidual double bond~ remaining
in the diene portion of the selecti~ely hydrogenated star polymsr
i8 typically employed. Preferably, at least one mole Or carboxylic
compound i8 u8ea for each olefinic un~aturation precent in the
selectively hydrogenated star polymer, with equivalent ratios of
carboxylic compound to olefinic double bond~ of between about 1:1
and 2:1 being particularly ~uitable. ~owever, les~ than
stoichiometric amount~ of oarboxylic compound may al~o be used.
The above reaction may occur with or without the use of
catalyst or radical initiator~ such as tertiary butyl hydroperoxide.
Any exces~ carbo~ylio compound is typically removed by either vacuum
aistillation or throu~h the use of a stripping gas stream.
In a preferred embodiment, the reaction Or the carboxylic com-
pound and ~tar polymer takes place in the presence of chlorine.
Chlorination has been disclosed with polymers of isobutene in U.E. -
Patent 949,981. The molar a~ount of chlorine used is preferably such
.:
.-~` ' ' ' ' : ' '` '', ', ': , '
~,:
7~
that the mixture of polymer and carboxylic compound i~ contacted
with from 0.3 to 1.5, more preferably from 0.5 to 1.2 mole~ of
chlorine for each mole of carboxylic compound. In~ofar a~ the
conversion of the polymer i~ oonoerned, there appeArs to be no
S lower limit on the amount of chlorine which may be u0ed. In
pra¢tice, however, it is preferred to rem~in within the
aforesaia ranges.
Suitably the mixture Or polymer and carboxylio ~ompound i~
heated to the reaction temperature before it is contacted with
the chlorine. The mixture i8 contacted with a mol~r deficienoy
of chlorine before any substantial amount, e.g. le88 than half
o* the carboxylic compound has reacted. Suitably9 sub~tantially
none of the carboxylic compound has reacted. The rate of
introduction of ohlorine into the mixture may vary between wide
limits but i8 preferably such that it equals the rate of ohlorine
uptake. Usually the chlorine i~ introduced over a period of
from 0.5 to ~0 hours, pre~erably from 3 to 7 hours.
After the chlorination treatment, it ~ advantageous to
subject the resultant product mi~ture to a po~t-reaction or ~
thermal treatment. ~his thermal treatment is suitably carried
out at a temperature in the range of from 140C to 220C,
preferably from 160C to 210C. ~he conditions are u~ually
~uch~ e.g. reflux oonditions, that sub~tantially no part of
the product mixture i8 removed durin~ this thermal treat~ent.
The thermal treatment may be for 0.1 to 20 hours, but i~
preferably from 0.5 to 10 hours. Lon~er period~ tend to increa~e
the formation of tarry by-products.
The star polymer may al~o be chlorinated before reaction with
the alpha, beta-un~aturated oarboxylic oompound. In this oase,
the hydrogenated polymer :i8 treated with about 0.5 to about 3
moles of chlorine (C12) per 100 c~rbon atoms of the polymer,
i.e. between about 2~ and 12~w C12, in a suitable chlorination
solvent. After a reaction period of from 0.5 to 2 hour~ at
between 0 and 100Cc unreacted chlorine and hydrogen chlorine
are remo~ed by ga~ stripping. The chlorination solvent may be
.
e~changed by distillation with a ~eoond oolvent such as a lube
oil base stook or other solvent suitable for the subsequent
step~ as described herein.
The ~odified polymer is then reacted with the amines and/or
polyol~ to form the oil-~oluble product of the ~n~tant inYention.
The resulting imides, esters and the like pro~ide the disper~ant
function of the additi~e.
The C1 to C1~ amine~ employed in the inatant in~ention oan
be branched or unbranched, saturated, aliphatic, primary or
secondary amines, containln~ 1 to 8 nitrogens, preferably mono-
or diaminen, ~uoh a~ ethylamine9 butylamine, Beo. butylamine,
diethylamine, etc., but including hi~her polyamines ~uoh as
alkylene polyamines, wherein pairs of nitrogen atom~ are ~oined
by alkylene groups of 2 to 4 oarbon atoms. Thu~, polyam~nes of
the formula:
NH2(CH2 ~n ~ NH(C~2~n}m~ H2
are included where n i~ 2 to 4 and m i8 0 to 6. Examples of ~uoh
polyamines inolude tetraethylene penta~ine, tripropylene tetramine,
N-aminoalkyl piperazine~, e.g., N-(2-aminoethyl) pipera~ine, N,N'-
di(2-aminoethyl) piperazine, etc. Preferred i~ tetraethylene
pentamine, as well as corresponding oommercial mixtures ~uoh a8
"Polyamine ~", and "Polyamine 500".
The alkane polyols useful in making the ester~ are alkane
polyols having at lea~t two and preferably at least four hydroxy
groups such as the trihydroxyalkanes, e.g. ethylene glycol,
propylene glyool, polymethylene ~lyools, trihydroxybutanes,
pentanes, hexanes, heptanos, ootanes, nonanes, dodecanes, etc.,
as well as tetrahydroxy alkanes, pentahydrosy alkanes, hexahydro~y
alkane~, as well as the sugar alcohol~ such as erythritol,
pentaerythritol, tetritols, pentitol~, hexitols, mannitol, sorbitol,
gluoose and the like. Partioularly preferred aloohol~ are
pentaerythritol and mannitol. ~speoially preferred is pentaerythritol.
The molar ratio of amine or polyol to carboxylio co~pound i8
typically between about 0.1:1 and about 2:19 preferably betw~en
about 0~5:1 and about 2:1, most preferably about 1:1. The conditions
.
,,~,~q3,~ 7r ~aæ
durin~ amidi3ation or e~terification are typioally about 1 50ffc to
250C for between about 1 hour and 20 houxs.
In both reaction steps it iB much pxeferred that the r~action~
take place in the absence of oxygen. A nitrogen blanket i8 often
used to accomplish this result. ~he r0a00n for performing the
reaction in the absence of oxygen i~ that the resultin~ additive
may be more oxidatively un~table if any o~ygen i8 pxesent during
the formation of the additive.
If excess amine or polyol iB employed, then it may be
desirable to remove the exce~. One means of doing this is to
first exchange the tri-chlorobenzene sol~ent for a lu~e base stock
by vacuum di~tillation, and then add a volume of heptane equal
to the volume of oil solution. Then an equal volume of methanol
is added and mixed. Two separate lsyers are therein formed upon
settling; one layer comprising predominantly wa~h ~olvent and
the unreacted amine or polyol, and a second layer compri~ing pre-
dominantly oil, heptane, and the additive productO After ~eparating
the wash layer, the volatiles present in the product layer can then
be removed by a distillation technique. Alternatively, the excess
amine or polyol may be removed under a vacuum or with a stripping
gas otream.
~ he reaction product of this in~ention can be incorporated
in lubricating oil oompositionc, a.g. automotive crankca~e oils,
in concentrations e.g. within the range of about 0.1 to about 15
preferably about O.1 to 3, wei~ht percent based on the weight of
the total co~positions. The lubri¢atin~ oil~ to whi¢h the sdditives
of the invention can be added include not only mineral lubricating
oils, but ~ynthetic oils also. Synthetic hydrocarbon lubricating
oils may al~o be ~mployed, as well a~ non-hydrocarbon ~ynthetio
oils including dibasic acid esters ~uch a~ ai-2-ethyl hexyl
sebacate, carbonate esters, phosphate esters, halogenated hydro-
carbons, polysilicones, polyglycol~, ~lyool e~ters such ~8 C13 oxo
acid diesters of tetraethylene glycol, etc. When used in gaso-
ine or fuel oil, e.g. die~el fuel, ~o. 2 fuel oil, etc., then
35 ~ usually about 0.001 to 0~5 weight percent, baced on the weight of
,: ~ . . ~ .. .
- 10 -
the total compo~ition of the reaction produot will be uued.
Conoentration~ ¢omprising a minor proportion, e.g. 15 to 45
weight peroent, of ~aid reaction produot in a ma~or amount of
hydrocarbon diluent, e.g. 85 to 55 weight peroent mineral
lubricatin~ oil, with or without other additive~ present, can
al~o be prepared for ea~e of handling.
In the above compositions or ooncentrates, other oonventional
additives may also be present, inoluding dye~, pour point
depressant~, antiwear agents, e.g. tricresgl phosphate, ~inc
dialkyl dithiophosphates of 3 to 8 carbon atoms, antioxidants such
a~ phenyl-alpha-naphthylamine, tert-ootylphenol sulphide~ bis-
phenols such as 4,4'-methylene bis(3,6-di-tert-butylphenol),
viscosity index improvers such a~ the ethylene-higher olefin
copolymer, polymethylacrylates, polyisobutylene, alkyl fumarate-
vinyl acetate copolymers, and the like a~ well as other a~hle~sdispersants or detergents ~uch as overbas~d sulphonates.
~ he invention is further illustrated by mean~ of the
following Examples, which ~ ~iven for the purpose
of illustration alonej and i8 not meant to limit the invention
to the particular reactant6 and amounts di~¢losed.
Example 1
A hydrogenated star-shaped polymer made from isoprene and
a divinyl benzene couplin~ agent was rea¢ted with maleic anhydride
and tetraethylenepentamin~ to form a di~persant/VI improver
aocording to the present invention.
~ he star-shaped polymer was prepared by first polymeri~ing
isoprene in a cyolohexane solvent with a se¢ondary butyl lithium
initiator. ~he polymer branch A-Li had a molecular weight of
about 45,700. The liYing polymer was then ¢oupled with commeroial
divinyl ben~ene (55% w~ight from Dow Chemi¢al) in a molar ratio
of divinyl benzene to lithium of 3:1. The coupled polymer had a
total mole¢ular weight of 577,000 on a polyntyrene equivalent
basis. Then the polymer wa~ hydro~enated with an aluminium
triethyl/nickel ootoate ¢ataly~t~ ~he final mole¢ular weight was
609,000, the ¢oupling yield wa~ 96%, the saturation inde~ wa~ 10%,
., ,, , . ~ ,. : :
, . . . . .
.: . ~ . .. ~, :
and residual un~aturation by ozone titration waa 0.11 milliequivalent~
per gram.
~ hen 10 g of the hydro~enated star-~haped polymer prepared
above w~ dis~olved in 190 g of a lube ba~e ~tock. ~o the polymer
solution was added maleio anhydride (0.80 g, 7.0 millimole~) and
the mi~ture heated to 225C for 8 hour~. Exoes~ maleic anhydride
was removed by di~tillation una0r vaouum. A small part Or the
solvent also came over. A nitrogen atmosphere was mai~tained up
until vacuum wa~ applied.
Tetra~thylenepentamine w~ added to tha maleatad polymer
solution and the mixture heated to 160C for 1 1/2 hour0 and 190C
for 1 1/2 hour~ under nitrogen.
The oil solution wa~ then cooled, diluted with heptane,
filtered, washed with methanol and stripped of volatiles. ~he
product contained about 1~ nitrogen on ~nactive material ba~
The dispersancy of the product was asse~sed by a Spot
Di~persancy Test. In the Spot Dispersancy Test, one part of a 2%
weight solution of the additive to be teeted in 100 parts neutral
oil is mixed with two parts used, sludge-containing oil and heated
overnight at 150C. ~lotter apots are then made on filter paper
and the ratio of a sludge spot diameter to ~1 ~pot diameter i8
measured after 24 hours. A poor value i8 under about 50%. The
additive prepared above yielded a value of 68%. Unmodified star
polymer gave a value of about 27%.
A 2% by weight concentration of the abo~e-prepared additive in a
com~n m~e~ lubricating oil base stock increased the 99C kinematic
vi~cosity from 4 centistokes for the lube ~tock alone to 21
centistokes for the lube oil plus additive. ~his visco~ity
increase demonstrates the usefulness Or the pre~ent additive a~
a ~I improver.
Exa~Ple ?
10 g of the hydrogenated star-shaped polymer prepared above
were dissolved in 190 g 1,2,4-trichlorobenzene. To the polymer
solution was added maleic anhydride (0.80 g, 7.0 millimoles)and the
mixture heated to 205~ for 4 hour~. Excess maleic anhydride ~a8
- ~
: ' ` , .:
~` ~ , ' ' .
"
- 12 -
removed by distillation under vacuum. A small part Or the solvent
al80 came over~ A nitro~en atmosphere was maintained up until vacuum
was applied.
Pentaerythritol (0.95 g, 7.0 millimoles)wa~ added to the
maleated polymer solution and the mixture heated to 205C for
4 hours under nitrogen. Unreacted pen-taerythritol wa~ removed
by distillation under vaouum.
An amount of a lu~e ba~e stock wa~ added whioh was equal in
volume to the reaotion mixture and the trichloroben~ene solvent
distilled under vacuum. The oil solution was then dlluted with
heptane, filtered, wa~hed with methanol and stripped of volatiles~
Disper~ant power of the oil-soluble produot wa~ readily
apparent from the formatlon of a stable emulsion during the washing
step. In addition, the dispersanoy of the product wa~ assessed
~15 by the Spot ~ispersanGy Test. The additive prepared above yielded
a value of 56%. ~nmodified star polymer ~ave a value of about 27%.
A 2~o by weight concentration of the above-prepared additive
in a common mineral lubrioating oil ba~e sto¢k inoreased the 99 C `~;
kinematic visoosity from 4 centi~tokes for the lube ~took alone
20 ~ to 15 oentistokes for the lube oil plu6 additive. Thi~ viscosity
inorea~e demon6trates the usefulne6s of the pre~ent additiue~as
a VI Improver.
::: :
::
~ ,
.~.- , - - ~
