Note: Descriptions are shown in the official language in which they were submitted.
3J ~ d ~J r ~ ?
HOECHST AKTIENGESELLSCHAFT HOE 89/F 320 Dr. DA/~ch
Description
Proces~ for the preparation of a polyolefin
The invention relates to an ole~in polym r having a high
molecular weight and a low residual catalyst content.
The preparation of isotactic PP is achieved with the aid
of ethylene-bis(4,5,6,7-tetrahydro-1-indenyl)zirconium
dichloride together with an aluminoxane in a su~pension
polymerization (cf. EP A 185,918). The polymer has a
narrow molecular weight distribution ~M~/M~ 1.6 to 2.6).
By means of a specific preactivation method~ it was
possible to achieve a 6ubstantial increase in the acti-
vity of the catalyst system (cf. DE 3,726l067). The ~rain
morphology of the polymer was also Lmproved by this
preactivation method.
The isotaxy ~or syndiotaxy) of the polyolefins can be
adjusted by selecting the polymerization temperature
(cf. DE 3,~26,075~ or the catalyst (cf. DE 3,826,075,
DE 3,726,067~. However, for certain polymerization
processes, it i~ desirable ko influence the i~otaxy (or
syndiotaxy) by means o~ a further component.
Accordingly, the ob~ect was to ~ind a proc~ss ~or ~he
preparation of a high-molecular-weight olefin polymer
which can be carrled ou~ in a temperature range ~hich is
of industrial interest and at a high cataly~t activity
and which make~ it pos~ible to control the isota~y or
syndiota~y in a sLmple manner.
It ha~ been found that the object can be achieved by th~
polymexization of olefins in the pre~ence of certain
m~tallocene catalyst~ and certain acti~ators~
~J ~ 3 ~J P,~ ~
Accc)rdingly, the invention relates to a proCess for ~he
prepara~ion of a polyolefin hy polymeri~a~ion o~ an
c: le~in of the ~ormula R~-CH=CH-Rb, in whiCh Ra and Rb are
identical or differen~ and are a hydrogen atom or a
C~-C14 alkyl radical or R~ and Rb, together with the carbon
atom linking khem, form a ring of 4 to 28 carbon atoms,
at a temperature of 0C to 150C, at a pre~sure of 0.5 to
100 bar, in solution, in suspension or in the ga3 phase,
; in the presence of a catalyst consisting of a metallocene
and an aluminoxane, wherein the aluminoxane i~ a compound
of the formula (I3
\ Al - O ~ Al - O ~ Al \ (I)
: for the linear type and/or of ~he formula (II)
.'
_ Al - O ~ ~
. n~2
:
for the cy~lic type, R1 in the fonmulae (I) and (II) being
a Cl-C6-alkyl group or a hydrogen atom and n being an
inkeger ~rom 2 to 50, 0.01 to 40~ of the radicals R1 being
hydrogen akom~.
The cataly~t to be u~ed for the proce~s according to the
invention comprise~ a me~allocene and an aluminoxane of
th~ formula ~I)
Rl Rl Rl
Al O ~ ~1-~ O - Al ~I)
R1 ~ n \ Rl
for the linear type and/or o ~he fonmula (II)
Rl
_ Al - O (II)
. n+2
for the cyclic type. In these formulae, R1 is a Cl C6-
alkyl gxoup, preferably methyl, ethyl or isobutyl, in
particular methyl, and n is an integer from 2 to 50,
S preferably S to 40 or a hydroge~ atom. In the~e formulae,
0.01 to 40%, preferably 0.01 to 35%, of the radical~ R1
are hydrogen atoms. Howevex, the ~act structure of the
aluminoxane is not known.
The aluminoxane can be prepared by various methods.
One possibility is the careful addition of water to a
dilute solution of a dialkylaluminum hydride by adding
the solutio~ of the dialkylaluminum hydride, preferably
dLmethylaluminum hydride and the water, each in small
portions, to an initially introduced relatively large
amount of an inert ol~ent and waiting after each addi-
tion until the 0volution o~ ga~ ha~ cea~ed.
In another proces~, finely powdered copper gulfate
pentahydrate i~ ~uspended in toluene and dialkylalumlnum
hydride is added in a glass flask under an inert ga~ at
about -20QC in such an amount that about 1 mvlecule of
CuSO~ ~ 5H20 i3 available or every 4 Al atom~. After ~low
hydrolysi~ with the elLmination of alkans ~nd hydrogen/
the reaction mixture i5 left at room temperature for 24
to 48 hours; during which it may have to be cooled so
that the temperature does not exceed 30~C. The copper
sulrate is then filtered off from the alumino~ane dis-
solved in toluene, and the solution is concQntrated in
vacuo. It i~ assumed that in this pxeparation proce~ the
low-molecular-weight aluminoxane~ condense to give higher
oligomer~O The ~olu~ion can al o be u ed as such.
Furthermoxe, aluminoxanes ~re ob~a.Lne~ by r~acking
_ 4 ~ J r,i
dial~ylaluminum hydride, pr0ferably d~ne~h~lalumi.num
hydride, dissolved in an iner~ alipha~ic or aromatic 901
vent, preferably hep~ane or toluene, with hydrated
aluminum salt~, preferably aluminum sulfa~e at a tempera~
tuxe of -20 to 100C. In thi~ reaction, the volume ra~io
of the solvent to the alkylaluminum hydride used i~
to 50:1 - preferably 5:1 - and the reaction tLme, which
can be controlled by the elLmin2tion o~ the alkane, i~ 1
to 200 hours - preferably 10 to 40 hour~.
Of the hydrated aluminum salts, in particular tho~e are
used which hava a high content of water of crystalliz-
ation. Particular preference is given to aluminum sulfate
: hydrate, in particular to the compounds Al2~SO4)3 . 16H2O
and Alz( S04 ) 3 . 18H2O, which haYe a particularly high
content of water of crystallization of 1~ and 18 mol of
H2O/mole of Al2( S04 ~ 3 respectively.
A further variation of preparing aluminoxanes comprises
dissolving dialkylaluminum hydride, preferably dimethyl-
aluminum hydride, in the su~pending agent, pxeferably in
the liquid monsmer, in heptane or toluene, initially
introduced into the polymerization boiler, and then
reacting the al~minum compound with water.
Apar~ frsm the proce~e~ ~or the preparation of
aluminoxane5 de~cribed above, furthar u~abl.e proce~ses
exist.
Variou~ compounds of thi~ type can be u~ed a3 metallo-
cenc, for example compounds of the formula I~
R4
/ ~ R~
R~ Ml ~
~ 3
R5
In formula III, ~ a m~tal from the group compri~ing
titanium, zirconium, hafnium, vanadium, niobium, tantalum
5 - ~'J'~,~J~ J~ ~.J ;~
and chromium, prefera~ly zirconium and hafnium.
R2 and R3 are identical or different and denote a hydrogen
atom, a Cl~Clo~r preferably Cl-C3-alkyl group, a Cl-C10-,
preferably C1-C3-alkoxy group, a C6-C10 , preferably C6-C~-
5 aryl group, a C6-C10-, preferably C6-C8-arylo~y group, a
C2-C10-, preferably C2 Cb-alkenyl group, a C7 -C~o~ I
preferably C7-C10 arylalkyl group, a C7 Cl4-, pre~erably
C7-C12-alkylaryl group, a C8-C40-, preferably Ca-Cl2-axyl-
alkenyl group, or a halogen ~tom, preferably chlorine.
10 R~ and R5 are different and are a mono- or p~lynuclear
hydrocarbon radical, which can form a sandwich ~tructure
with the central atom M1.
R4 and R5 are preferably fluorenyl and cyclopentadienyl,
it being possible for the parent structures to carry
15 additional substituents.
R6 is a bridge comprising one or more members, which links
the radicals R4 and R5 and is
R7 R7 R7 R7 R7 R7 R7 R7
-M2- _M2_M2_ , -M2_~R9_ , ~C- , -O-M~ C~
R8 R8 R8 R8 RB R8 R8 ~8
=BR7, =AlR7, -Ge-, -Sn-, ~0-, -S-, ~SO, -S2~ =NR7, ~CO,
=PR7 or =P(o)R7, in which R7, R~ and R~ are identical or
20 dif~erent and are a hydrogen atom/ a halogen a~om,
preferably chlorine, a C1-C10-~ preferably C1-C3-al~yl
group, in particular a methyl group, a Cl-C10-fluoroalkyl
group, pxeferably CF3 group, a C6-C10-fluoro~ryl group,
preferably pentafluorophenyl group, a C~-C10-; preferably
: 25 C6-C8~aryl group, a Cl-C10-, preferably Cl-C4 lkoxy group,
in particular a methoxy group, a C2-C10-, preferably C2-
C4-alkenyl group, a C7-C40-, preferably C7-C10-a~yl~lkyl
group, a Ca-C40-, prefera~ly C8-C12-arylalkenyl group or a
C7-C40-, preferably C7-C~2-alkylaryl group, or ~6 and R7 or
30 R6 and R8, together with the atoms linXing th~m, each form
h glJ ~.. (i ~) 3 ,jl
- 6 --
a ring.
M2 is silicon, germanium or tin, prefexably silicon or
germanium.
R6 is preferably =CR7Ra, =SiR7Ra, =~eR7Ra, -O-, -S-, =SO,
5 =PR7 or =P(o)R7.
The metallocenes described above can be prepared accor-
: ding to ~he following general reaction scheme:
H2R4+ButylLi-~ HR4Li
X_R6_X HR4 R6_R5H 2-BUtYl~i
R5+ButylLi--HR5L1
LiR4-R5-R5Li MlC14_~
R4 R4 R4
R6 Ml R2Lir R6 M1 ~ ~6 / '1
R5 R5 ~5
(X - Cl, Br, I, O~tosyl)
~J 3~ ~JJ ~ J ~
or
H~R4 ~ ButylLi ~HR4Li
\ C/ ~L~5 R7R~C\
2 Butyll.i
[ R7~8~ ~ L1
R4
MlCl"
R4
/1 1
\ 1 5
R
R2Li
R4 R4
/1 1~ ~ \, /Ml~
R5 E~5
Examples of ~uitable metallocene~ are bi~(indenyl)~thyl-
eneæirconium dichloride, bis ( indenyl ) ethylenehafnium di-
chlorids, bi3 ( indenyl ) dimethyl~ilylene~irconium dichlo-
ride, bis(indenyl)dimethylæilyleneha~nium dichloride,
- 8 -
furthermore (arylalkylidene)(9-fluorellyl)(cyclopentadi~
enyl~zirconiu~ dichlsride, (diarylmethylene)(9-fluoren-
yl)(cyclopentadienyl)zirconium dichlori~e, and (dial~yl-
methylene)(9-fluorenyl)~cyclopentadienyl)zirconium
dichloride, and the corresponding hafnium compounds.
Before its use in the polymerization reaction, i~ i~
possible to preactivate the metallocene with an alumin-
oxane of the formula (I) and/or (II). This substantially
increases the polymerization activity and Lmprove~ the
grain morphology.
The preactivation of the transition metal compound is
carried out in solution Preferably, the metallocene is
dissolved in a solution of the aluminoxane in an i~ert
hydrocarbon. Suitable inert hydrocarbons are aliphatic or
~5 aromatic hydrocarbons.
Preferably, toluene is used.
The concentration of the aluminoxane in the solution is
in the range of about 1% by weight up to the saturakion
lLmit, preferably 5 to 30% by weight, in each case
relative to the entire solution. The metallocene can b~
used in the ~me concentration, but preferably it i~ u~ed
in an amount of 10-4-1 mol per mole of aluminox~ne~ The
preactivation tlme is 5 mlnutes to 60 hours, preferabl~
5 to 60 minutes. qlhe preactivation is carriad out at
temperature o~ -78~C to 100C, pre~erably 0 to 70C.
The pol~merization is carried ou~ in a known manner i~
solution, in suspension or in the ga~ phase, continuously
or batchwise, in one or more step~ at a temperatuxe of 30
to 150C, preferably 30 to 80~C. The olefin~ w.hich are
pol~meri~ed are those of the for~la RU-C~-CH~Rb. In thi~
formula, R~ and R~ are identical or different and are a
hydrogen atom or an alkyl radical of 1 to 28 carbon
atoms. However, Ra and Rb, together with the carbon a~om~
linking them, can also form a ring of 4 ~o 28 car~on
~J i~ ~J
9 _
atoms. Exa~ples of olefin of thi~ type are ethylene,
propylene, 1-bu~ene, 1-hexene, 4-methyl-1-pentene,
l-octene, norbornene, norbornadiene, pentene, hexene or
octene. Especially propylene is polymerized.
If neces~ary, hydrogen is added as a mvlecular weight
xegulator. The total pressure in the polymerization
system is 0.5 to 100 bar. The polymerization in the
pressure range of 5 to 64 bar, which is of particular
industrial interest, is preferr~d.
The metallocene compound is u~ed in a concentration~
relative to the transition metal, of 10-3 to 10-7,
preferably 10-4 to 10-6, mol of transi~ion metal per d~3
of solvent or per dm9 of reactor volume. The aluminoxane
is used in a concentration of 10-5 to 10~1 mol, preferably
10-4 to 10-2 mol, per dm3 of solvent or per dm3 of reactor
volume. However, in principle, higher concentrations are
also possible. At least one compound of the formula III
is used a~ the metallocene. Mixtures of ~everal compounds
of the formula III or mixtures of isomers are also
po~sible.
If the polymerization is carried out a~ suspension or
solution polymeriæation~ an inert ~ol~ent cus~omary ~or
the Ziegler low-pressure proces~ is used. For oxampla~
the polymerization i^~ carried out in an aliphatic or
cycloaliphatic hydrocarbon; exz~rnples of ~uch a hydro-
carbon are ~utane, pentane, hexane, heptane, isooc~ane,
cyclohexane, methylcyclohexane~
Furthermore, a benzine or hydrogenated diesQl oil frac-
tion can be used. Toluene i8 also u able. Preferably, the
polymerization i6 ca.rried out in ~he liguid mo~omer. If
inert sol~ent~ are used, the monomers are metered in as
a gas or a liquid. If only one monomer is used a3 su~pen
ding agent, the comonomer or-comonomer~ are metered in a~
a gas or li~uid. Furthermore, it i8 posslble to carry out
the polymerization in a mixture of different monomer~ as
- 19 ~ "7
suspending agent; a further monomer can ~hen be metered
in as a liquid or a gas. If ethylene is used, it i~
advantayeous to introduce initially a portion of the
ethylene and meter in the remainder during the
polymerization.
The duration of th~ polymerization i5 as desired, since
the catalyst system to be used according to the invention
shows only a small time-dependent drop in pol~merization
activi~y.
Tha process according to the invention is distinguished
by the ~ ct that the metallocenes used are very tempera-
ture stable, so that ~hey can be used with high activity
even at temperatures of up to 90C. Furthermore, the
aluminoxanes which serve a~ cocatalysts can be added in
smaller concentrations than previously. Finally, it i~
now possible to prepare random copol~mers at tempera~ures
which ar~ of industrial intexest.
A further advantage of the proce~s accoxding to the
invention i8 that ~he mixture of methylaluminoxane and
hydridomethylaluminoxane offer~ tha po~ibility ko
control the i otaxy or syndiotaxy of the pol~er.
The example~ which follow are intended to illu~trat0 tha
invention. The ~ymbol8 have the following meanings s
VN = visco~ity number in cm35 SI = ~yndiotactic index/ dete.rmined by l3C-NMR
speckro~copy
II = isotactic index, determined by '3
spectroscopy
E:~ample 1
A dry 16 dm3reactor wa~ flu~hed with nitrogen and filled
wikh 10 clm3 of liquid propylene. 68 cm3 of a hydrido-
me~hylaluminoxane ~olution in toluene (= XM~O, corres~
ponding to 40 mmol of Al, mean oligomerizatlon degree
~ 13 ~3J ~
n = 30) were then added, and the batch was stirred at
30C for 15 minutes.
':
At the same t~, 50 mg of bis(indenyl)ethylenehafnium
dichloride were dissolved in 34 cm3 MAO (= 20 mmol Al)
and preactivated by letting it stand for 15 minutes.
This solution was then poured into the reactor. The
polymarization system was brought to a temperature of
70C, and the polymerization began. The polymeri~ation
wa~ stopped after 60 minuteq by cooling the reactor and
releasiny the pressure. 0.16 kg of polypropylene was
obtained. The activity was therefore 3.2 kg of PP/g of
metallocene/h.
The following analytical data of the polymer were
determined:
VN = 73 cm3/g~ II = 92%.
~ xample 2
.~
A dry 16 dm3 reactor wa~ flushed with nitrogen and filled
with 10 dm3 of liquid propylene. 68 cm3 of a hydri~o-
methylaluminoxane ~olution in toluene (= HMAO,
corre~pondLng to 40 mmol o~ Al, mean oligomerization
degree n = 30~ were then added, and the batch wa~ 3tixred
at 30C for 15 minutesO
~t the same ~, 7 mg of bi~(indenyl)dimethyl~ilylene-
zirconium dichloride were di3solved in lS cm3 MAO
~= 20 mmol Al~ and preactivated by letting it stand for
15 minutes.
This so1u~ion was then poured into the reacto~- The
polymerization system was brought to a ~emperature of
70C, and the polymerization began. ~he polymerization
was ~topped after 60 minu~es by cooling the reactor and
releasing the pressure. 0.88 kg of polypropylene W~5
obtained. The activity was therefore 126 kg of PP~g of
~2~,~", 1
- 12 -
metallocene/h.
The followlng analytical data of ~he polymer were
determined:
VN = 49 cm3/g~ II = 85%.
E2ampl~ 3
A dry 16 dm3 reactorwas flu~hed with nitrogen and filled
with 10 dm3 of liquid propylene. 68 cm3 of a hydrido-
methylaluminoxane solution in toluene (= HMA0, oorres-
ponding to 40 mmol of Al, mean oligomerizati~n degree
n = 30) were then added, and the batch was ~tirred at
30C for 15 minutes.
At the same t ~ , 60 mg of fluorenylisopropylidenecyclo-
pen~adienylhafnium dichloride were dissolved in 34 cm3
HMAO (= 20 mmol Al) and preactivated by letting it stand
for 15 minutes.
This solution was then poured into the reactor. The
polymerization system wa~ brought to ~ temperature of
60C, and the polymerization began. The polymerization
was ~topped after 60 minutes by cooling the reactor and
relea~ing the pres~uxe. 1.45 kg of polypropylene were
obtainad. Th~ actiYity wa~ thexefore 11.9 kg of PP/g o~
metallocene/h.
The following analytical data o~ the polymer were
determined~
~S VN = 51~ cm3/g, SI = 92%.
~ample 4
A dry 16 dm3 rea~torwa~ flu~hed with nitrogen and illed
with 10 dm3 of liquid propylene. 68 cm3 of a hydrido-
methylaluminoxane solution in toluene ~= H~A0, corr2s-
ponding to 40 mmol of Al, mean oli~omeriza~ion degreen = 30) were then added~ and the batch wa~ . irrsd at
- 13 ~ 3 ~
30C ~or lS minutes.
At the same t ~ , 20 mg of fluoxenylisopropylidenecyclo-
pentadienylzirconium dichloride were dissol~ed in 34 cm3
HMAO (= 20 mmol Al) and preactivated by letting it stand
for 15 minutes.
This solution was then poured into the reactor. The
polymerization system was brought to a temp~rature of
50C, and the polymerization bPgan. The polymerizat.ion
was stopped after 60 minutes by cooling the reactor and
releasing the pressure. 0.68 kg of polypropylene was
obtained. The activi y wa~ therefore 34 kg of PP/g of
metallocene/h.
The following analytical data of the polymer were
determined:
lS VN = 123 cm3/g, 5I = 89%.
