Note: Descriptions are shown in the official language in which they were submitted.
2~879~8
HOECHST AKTIENGESELLSC~ T HOE 92/F 016 Dr. LO/PL
Description
Catalyst for the polymerization of olefins, proc~ss for
the preparation thereof, and use thereof
The present invention relates to a heterogeneous
~insoluble) catalyst which can advantageously be e~ployed
in the polymerization of olefins.
; Processes are known for the preparation o~ polyolefins
with the aid of homogeneous catalyst systems comprising
a transition-metal component of the metallocene type and
a cocatalyst component, an oligomeric aluminum compound
; of the aluminoxan type (usually methylaluminoxane~, which
have high activity and give polymers or copolymers having
a narrow molecular weight distribution (cf. EP/A-69 951).
A major disadvantage of these soluble (homogeneous)
metallocene/methylaluminoxane catalyst systems in pro~
cesses in which the polymer is formed as a solid is the
formation of thick deposits on reactor walls and stir-
rers. These deposits are always formed by agglomeration
; 20 (Polymer Commun. (1991) 32, 58) of the polymer particles
if metallocene or aluminoxane or both are dissolved in
the suspension medium. ~eposits of this t~pe in the
reactor systems must regularly be removeA, since they
rapidly achieve considerable thicknesses, have high
strength and prevent heat exchange with the cooling
medium.
In order to avoid the formation of deposits in the
reactor, ~upported catalyst systems have been proposed,
in which the metallocene and/or the aluminum compound
s~r~ing as cocatalyst are immobilized on an inorganic
support material (cf~ EP-A-206 794). In addition to the
use of an additional support material which is present in
~ 2~87~8
- 2 _
the polymerization product ~ormed, thsse system have the
disadvantage thak reactor deposits continue to be formed,
in particular in the case of suspension polymerization.
Insoluble aluminoxane products have already been des-
cribed (J. Am. Chem. Soc., 90 (lg68~ 3173), but ha~e not
been used for polymerization reactions.
EP-A 363 029 describes low-solubility methylaluminoxane
which, together with a soluble metallocene and optionally
a further soluble aluminum compound, is used as a poly-
merization catalyst system.
Use of this catalyst system in suspension or bulk poly-
merization reactions continues to give reactor deposits.
A further disadvantage of polymerization using soluble
metallocene/methylaluminoxane systems is the poor bulk
densities of the polymer powder produced, and the high
proportions of fine particles (< 100 ~m) sometimes
formed. Poor bulk densities cause high cosks for removal
of the polymer from the reactor, require a complex drying
process and also reduce the capacity of the polymeriza-
tion reactor; the high proportions of fine particles areparticularly disadvantageous in the various process steps
of furthex processing of the polymer.
A significant part of the catalyst costs in the case of
polymerization using homogeneous metallocene catalyst
systems is due to the methylalumino~ane (MAO~ or to its
preparation from water and trimethylaluminum. The yield
of soluble MAO is reduced, in particular, by the forma-
tion of insoluble methylaluminoxane, which is up to 10%
by weight or more, depending on the intended degree of
MAO oligomerization. It is therefore desirable for the
insoluble MA0 by-products also to have an indus~rial use.
_ 3 _ X~879
:
The object was thus to find a polymerization process or
a cakalyst system which avoids the disadvantages known
from the prior art.
Surprisingly, it has been found that reaction of an
aluminum compound A comprising a specific oligomeric
aluminoxane with metallocenes B gives a highly active
polymerization catalyst which completely prevents reactor
. deposits.
The invention thus relates to a catalyst for ~he poly
merization of olefins, comprising the product of the
reaction of an aluminoxane which is insoluble in alipha-
tic and aromatic hydrocarbons with at least one metal-
locene.
The ~atalyst formed is solid and is insoluble in alipha-
tic hydrocarbons such as hexane or diesel oil (boilingfraction: 100-120C~ and likewise in aromatic hydrocar-
bons such as benzene or toluene (heterogeneous catalyst).
;
The aluminoxane to be used according to the invention is
a solid substance which is likewise insoluble in the
abovemen~ioned solvents. The solid, insoluble aluminoxane
is formed as a by-product during the p.reparation o~
toluene-soluble aluminoxanes from an organoaluminum
compound AlR3 and water. In the compound AlR3, the
radicals are identical or different, preferably identi-
cal, and are C1-C6 alkyl, C6-C10-aryl or ben2yl. In par~
ticular, R is a methyl group.
The preparation of said toluene soluble, oligomeric
aluminoxanes can be carried out in a variety of ways and
is known from the literature (cf., for example,
Polyhedron 9, 1990, 429).
Preference is given to insoluble aluminoxanes formed as
by~products in processes in which AlR3 is reacted directly
~ 2~87~1~
with (free) water. If the water neces6ary ~or the reac-
tion is provided in the form of adæorbed or absorbed
water, for example as water of crystallization in the
reaction of AlR3 with CuSO4 5HzO, the insoluble aluminox-
ane formed as by-product is contaminated hy metal qalts
(for example CuSO4~ or other inert materials. In prin-
ciple, however, by-products of this type can also be used
: according to the invention.
The preparation of soluble, oligomeric aluminoxanes from
AlR3 and water is described, for example, in DE-A
4 004 477. The by-products produced therein are prefer-
ably used as insoluble aluminoxanes according to the
invention.
The process described in DE-A 4 004 477 can be varied by
changing the reaction stoichiometry (increase in the
amount of water added), 60 that insoluble, solid alumin-
oxanes become the major or only reaction product.
The aluminoxanes according to the in~ention can also be
prepared by the process described in EP-A-363 0~9.
The precise structure of the aluminoxanes according to
the invention is not known. They are presumably mixtures
of compounds of different composition. The empirical
formula of the aluminoxa.nes preferably empl4yed is AlO~Rb
where 0.5 s a ~ 1.3 and O.S s b ~ 2. The R radicals are
identical or different, preferably identical, radicals
and are C1-C6-alkyl, C6 Cl0-aryl or benzyl. R is preferably
C1-C4-alkyl, in particular methyl; ie. insoluble methyl-
aluminoxane is particularly preferred.
Hoever, whether an aluminoxane is suitable for the
purpose according to the invention is determined less by
its empirical formula than by the fact that it must be
insoluble, in particular, in tolu~ne and benzene.
` 2~87~:18
-- 5 --
The aluminoxanes which have hitherto been used as coca~a~
lysts in polymerization reactions are ~oluhle at least in
toluene, but preferably also in other hydrocarhons.
The second starting compound for the preparation of khe
catalyst according to the invention is a transition-metal
compound in the form of a metallocene. It is preferably
a metallocene that i5 reacted with the aluminoxane.
-
It is also possible to employ a plurality of metallocenesand/or various aluminoxanes as reactants. The catalysts
resulting from the use of a plurality of metallocenes are
particularly suitable for the preparation of so-called
reactor blends.
In principle, it is possible to employ any metallocene,
irrespective of it~ structure and composition. The
metallocenes can be either bridged or unbridged/ and have
identical or different ligands. They are compounds of the
metals from Groups IVb, Vb or VIb o~ the Periodic Table,
for example compounds of titanium, zirconium, hafnium,
vanadium, niobium, tantalum, chromium, molybdenum or
tunysten, preferably of xirconium, ha~nium or titanium,
in particular of æirconium.
I'hese metallocenes are known and are de~cribed, for
example, in the following doc~ents: EP-A-336 127, EP-A~
336 128, EP-A-387 690, EP-A-387 691, EP-A-302 424r EP-A-
129 368, EP-A-320 762l EP-A-284 707, ~P A-316 155, EP A-
351 392, US-A-5,017,714 and J. Organomet. Chem., 342
(1988~ 21.
Of particular interest are metallocenes, specifically
zirconocenes, which carry indenyl derivatives as ligands.
30 These are preferably the compounds of the formula I
2~7~:l8
R~ R5
~'~' (1)
~ R 1
R ~ R 2
~ R 5
in which
Ml is a metal from Group IVb, Vb or VIb of the Periodic
Table,
R1 and R2 are identical or differerlt and are a hydrogen
atom, a C,-C10-alkyl group, a C1-C10-alkoxy group, a C6-C10-
~ aryl group, a C6-C10-aryloxy group, a C2-C10-alkenyl group,
-: a C7-C40-arylalkyl group, a C7-C~,O-alkylaryl groupl a C3-
C40-arylalkenyl group, an OH group or a halogen atom,
the R3 radicals are identical or dif~erent and are a
hydrogen atom, a halogen atom, a C1-Cl0-alkyl group, wh:i.ch
may ~e halogenated, a C6-C10-aryl group, an -NR2, -SR, -
OSiR3, -SiR3 or -PR2 radical in which R is a halogen atom,
a C1-C10-alkyl group or a C3-C10-aryl group,
R~ to R3 are as define~ for R3, or adjacent radicals R4 to
R8, together with the atoms connecting th~m, form an
aromatic or aliphatic ring,
2~91~
-- 7 --
R9 is
R' R'~ P~' Rl R10 R10
- M2 M2 M9- - C - C . o - M2- 0 -,
I l l l l I
`: R" R'1 R11 R'l Rl~ Rl'
R' R' F~lo R~
l l
- C -, - O - M2,, C M2,
l l
R~1 ~11 R
=BR1C, =AIR10, -Ge-, -Sn-l -O-, -S-, =SO, =SO2, =NRl, =CO,
5 =PR10 or =P(O)Rl, where
Rl and R1l are identical or different and are a hydrogen
atom, a halogen atom, a Cl-ClO-alkyl group, a Cl-C1O-fluoro-
alkyl group, a C6-C1O-aryl group, a C6-C1O-fluoroaryl group,
a Cl-C1O-alkoxy group, a C2-C1O~alkenyl group, a C7-C40-
arylalkyl group, a C8-C40-arylalkenyl group, or a C7-Cl4-
alkylaryl group or Rl and Rll, in each case together with
the atoms connecting them form a ring, and
M2 iS silicon, germanium or tin.
The 4,5,6,7-tetrahydroindenyl analogs corresponding to
the compounds I are likewise of importance.
In the formula I, it is preferred that
Ml is zirconi~n,
Rl and R2 are identical and are methyl or chlorine, in
particular chlorine,
R3-R3 are hydrogen or C~-C4-alkyl,
R9 is
~7~
-- 8
R' R' R' R'
-Si- ~ or ~.~ , where
Rl' ~11 Rll
Rl and R1l are identical or different and are C1-C4-alkyl
or C6 C10-aryl. In particular, Rl and ~11 are identical or
different and are methyl or phenyl.
.
The indenyl or tetrahydroindenyl ligands in the formula
I are preferably substituted in the 2-, 2,4-, 4,7-, 2,6-,
2,4,6-, 2,5,6-, 2,4,5,6- or 2,4,5,6,7-position, in
particular in the 2,4,6-position. Substitution is prefer-
ably by a Cl-C4-alkyl group, such as, for example, methyl,
ethyl or isopropyl. The 2-position is preferably sub-
stituted by methyl.
of particular importance are furthermore compounds I in
which the substituents in the 4- and 5-positions of the
indenyl radicals (Rs and R6), together with the atoms
connecting them, form a benzene ring. This fused ring
system may likewise be substituted by radicals as defined
for R3 - R~. An example which may be mentioned of such a
compound I is dimethylsilanediylbis(2-methyl-4,5-benzo-
indenyl)zirconium dichloride.
The metallocenes I are particularly suitable for the
preparation of high-molecular-weight polyolefins of high
stereoregularityO
The metallocenes I and the metallocenes described in th~
documents mentioned can be prepared, for example, in
accordance with the reaction scheme below:
2~87~1~
g
~2R' ~ 5utrl L i ~HR'L i X-R9-X
~ omitt~d foL unbridged
H 2 ;I d + B u ~ y I L i ~ H R d L I m~talloc~nQ~ )
H R ' - R 9 - R d H 2 3 u ~ y I L i,
L i 2 ' R 9 ;; d L i 4 ~
;
R'~ RC~ R1
5' 5 M 1 ~ C I H~,~ . R 1 ~ j / M 1 ~
' `` dC I P t 2 ~ \ R d ~' C I
2 L / ~ ~ R
R9 M \ R2
\ Rd~
X = Cl, Br, I or O-tosyl; H2RC and HzRd - ligands, for
example (subst.)indene
* additional hydrogenation step if, for example, indenyl
ligands are to he converted into tetrahydroindenyl
ligands.
~he preparation processes are known in principle from the
literature; cf. Journal of Organometallic Chem. 288
(1985) 63 - 67, EP-A-320 762 and the documents cited
t~erein concerning the metallocenes described ther~in.
The starting materials used for the preparation of the
compounds I are variously substituted indenes (H2RC and
HzRd; cf. the above reaction scheme). Some of these indene
derivatives are known and commercially available.
2al87~
-- 10 --
Specifically substituted indenes can be prepared by the
pxocess indicated below:
a) H2RC and H2Rd = ~R4
, ~ /
X \ R3
H H
The synthesis is carried out as described in or analo-
gously to the literature references below:
J. Org. Chem., 49 (1984) 4226 - 4237, J. Chem. Soc./
Perkin II, 1981, 403 - 408, J. Am. Chem. Soc., 106 t1984)
6702, J. Am. Chem. Soc./ 65 (1943) 567/ J. Med. Chem./ 30
(1987) 1303 - 1308/ Chem. Ber. 85 (1952) 78 - 85.
d Rs
b) H2RC and H2R =
~ 3
H H
The preparation of the 2,4~substituted indenes H2RC and
H2Rd used as starting substances ls possible by 2 dif-
ferent routes:
bl) The starting compound used is a keto-aldehyde o~ the
Eormula shown in the reaction scheme below; it5 prepara-
tion is known (Synthesis 1985, 1058).
The reaction of this keto-aldehyde with cyclopentadiene
is carried out in an inert solvent in the presence of a
base. Preference is given to alcohols, such as methanol,
ethanol or t-butanol, in particular methanol.
The bases used can be a wide range of compounds. Examples
which may be mentioned are alkali or alkaline earth metal
.
~79~
11
; hydroxides, alkali and alkaline earth metal alkoxides,
such as sodium methoxide, sodium ethoxide and sodium
tertiary butoxide, amides such as lithium diisopropyl~
amide, and amines. Preference is given to sodium ethox-
ide, potassium tertiary butoxide and potassium hydroxide.
`:
The molar ratios between starting compounds, including
the base used, can vary within broad limits. The keto-
; aldehyde:cyclopentadiene~base molar ratio is preferably from 1 : 1 - 1.5 : 2 - 3, in particular 1 ~ 2.5.
The reaction temperature is preferably from -40 to 10~C,
in particular from O to 25C.
The reaction times generally vary between 10 minutes and
100 hours, preferably between 1 hour and 30 hours.
The substituent in the 2-position can be introduced by a
Grignard reaction after the 4-monosubstituted indene has
been converted into the 4-monosubstituted 2-indanone by
a general working procedure (Organic Synthesi.s, Coll.
Vol. V, 1973, 647). The subsequent eli.mination of water
: gives the 2,4-substituted indenes.
The 2,4-substituted inden~s are produced in the Eorm of
double-bond isomers, which can be employed directly for
the synthesis of the corresponding metallocene complexes.
RS Rs RS
~0 + ~ ~ ~3 ' l 1 '=~
,",~
~ R 3
\~ /
29~79~8
- 12 -
b2) Another possible and adYantageous strategy proceeds
in accordance with the scheme below:
A 2-substituted benzyl halide is reacted with an appro-
priately substituted malonic diester analogously to a
process known from the literature ~J. Org. Chem. 1958,
23, 1437) to give the disubstituted malonic diester.
Hydrolysis of the diester and decarboxylation by conven-
tional processes gives a disubstituted propionic acid
derivative.
Ring closure to give the 2,4-disubstituted l-indanone is
carried out by customary processes ~Friedel-Crafts
r~action) after the carboxylic acid has been converted
into the carboxylic acid chloride~
Reduction of the ketone by known methods and subsequent
elimination of water gives the 2,4-disubstituted indenes.
c) H2R~ and H2Rd = R S
R6 R'
H H
rrhe compounds H2RC and H2Rd are prepared by reactincJ a
compound II
R~
R7
with a compound III
- 13 _ ~87
R ,~
R4H2C-C -C ~2
or the anhydride thereof in the presence of a
Friedel-Crafts catalyst. In this formula, X1 and X2 are a
nucleophilic leaving group, such as, for example, ~lalo-
S gen, a hydroxyl group or a tosyl group, in particularbromine or chlorine.
This gives the indanones IV or IVa
: Rs R4 RS
R3
Rs ~ (IV) R8 R4 (IV~)
The indanones can be formed as two constitutional isomers
of the formula IV and IVa, depending on the substitution
pattern on the aromatic ring. These, in pure fo~m or as
a mixture, can be reduced to the corresponding indanols
by methods known ~rom the literature using reducing
agents such as NaBH,, or LiAlH4, and subsequently dehydra-
ted to give indenes of the formula V or Va (H2RC/H2Rd) by
means of acids such as sulfuric acid, oxalic acid or p-
toluenesulfonic acid, or alternatively by treatment with
dehydrating substances, such as magnesium sulfate~ sodium
sulfate, aluminum oxide, silica gel or molecular sieve
(Bull. Soc. Chim. Fr. 11 (1973) 3092; Organomet~ 9 (1990)
3098).
g~lg
14 -
R5 R5 R
R~ ~ _ ^ \ ~ R~
R~ R4 (V) R8 (V~)
Examples ~f suitable Friedel-Crafts catalyst~ are AlCl3,
AlBr3, FeCl3, SbCl5, SnCl4, BF3, TiCl4, ZnCl2, H25O4, poly-
phosphoric acid, H3PO4 or an AlCl3/NaCl melt, in part~icular AlCl3.
Tha starting compounds of the formulae II and III are
known and commercially available or can be prepared by
processes known from the literature.
The reaction is carried out in an inert solvent. Methyl-
ene chloride or CS2 i5 preferred. If the starting com-
ponents are liquid, there is no need to use a solvent.
The molar ratios between the starting compounds, includ-
ing the Friedel-Cxafts catalyst, can vary within broad
limits. The compound II ~ c~talyst molar ratio is
preferably from 1 : 0.5 - 1.5 : 1 - 5, in parkicular
~ 2.5 - 3.
The reaction temperature is preerably from 0 to 130C,
ln particular from 25 to 80C.
The reaction times generally vary hetween 30 minutes and
100 hours, preferably between 2 hours and 30 hours.
In a preferred procedure, the Friedel-Crafts catalyst is
metered into a mixture of the compounds II and III. The
reverse sequence of addition is also possible.
The indanones of the formula IV and IVa can be purified
bydistillation, column chromatography orcrystallization.
2~8~1e9~ ~
- 15 -
The substituted indenes can be formed a~ double-bond
isomers (V/va). These can be purified from by-products by
distillation, column chroma~ography or crystallization.
Starting from ~he indenes of the fo~nulae V and Va~ which
can be emplGyed as a mixture of isomers, the preparation
of the metallocenes I proceeds by processes known from
the literature (cf. AU-A-31 478/89, J. Organomet. Chem.
342 (1988) 21, and EP-A-284 707), in accordance with the
reaction scheme shown.
10 d) H2RC and H2Rd = R6
RS R7
R~ l where R12 and R13 are as
~ R8 defined for R4 - R~
H H Rl3
These benzo-fused indenes are prepared and further
converted into the metallocenes I as shown in the reac-
tion scheme below:
~ 16 ~ 2~8~9~8
r~
o ~
o
G~--~
.~ Y~ ~
_ ~
~ = ~n ~ ~
.'., CC; ~ ~
Z 2r c~ CJ
O I ~_ _ O
Y I d 1 ~ ~u
,, , ~ ~
y / ~ ~
. ~ O
O , ~
-- ~ ~ J, C
~/ --I '.1 0
~1 ~J
~ O
," / r~ X ~ ~ ~ V
;~ ~ I
\
~ ._
r~
- 17 ~ 7g~
The naphthalene deri~akives of the ~ormula A are commer~
cially available or can be prspared by methods known from
the literature ("Friedel Cxafts and Related Reactionsll,
Wiley, New York, 1964, Vol. II, pp. 659 - 766, Bull. Soc.
Chim. Belges, 58 (1949) 87, J. Amer. Chem. SoC. 89 (1967)
2~11).
- The conversion to the compounds of the formula C is
carried out by methods known from the literature ~y
reaction with substituted malonic esters of the ~ormula
B under basic conditions, such as, for example, in
ethanolic solutions of sodium ethoxide (J. Org. Chem. 23
(1958) 1441, J. Am. Chem. Soc. 70 (1948) 3569).
The compounds of the formula C are hydrolyzed by methods
known from the literature using alkali metal hydroxides,
such as potassium hydroxide or sodium hydroxide, and
decarboxylated by methods known from the literature by
thermolysis of the resultant dicarboxylic acid to give
the compounds of the formula D (J. Org. Chem. 23 (1958)
1441, J. Am. Chem. Soc. 70 (1948) 3569).
The ring closure to give the substituted benzoindanones
of the formula E is carried out by methods known from the
literature by reaction with chlorinating reagents, such
as, for example, SOCl2, to give the corresponding acid
chloride~ and sub~equenk cyclization by means of a
Friedel Cra~ts catalyst in an inert solvent, ~uch as, for
example, using AlCl3 or polyphosphoric acid in methylene
chloride or CS2 (Organometallics 9 (1990) 3098, ~ull. Soc.
Chim. Fr. 3 (1967) 988, J. Org. Chem. 49 (1984) 4226).
The conversion to the benzoindene deri~atives of the
formula G is carried out by methods known from the
literature by reduction using sodium borohydride or
lithium aluminum hydride in an inert solvent, such as,
for example, diethyl ether or THF, or by alkylation using
alkylating agents of the formula F or using alkyllithium
1~ 2~8~
compounds to give the corresponding alcohols and dehydra-
tion of the alcohols undar acidic onditions, such as,
for example, using p-toluene6ulfonic acid or oxalic acid,
or by reaction with dehydrating substances, such as
magnesium sulfate or molecular sieve (Oryanometallics 9
(1990) 30~8, Acta Chem. Scand. B 30 (1976) ~27, J. Amer.
Chem. Soc. 65 (1943) 567).
The benzoindene derivatives of the formula G can also be
synthesized by another synthetic route, not shown in
greater detail here, in 4 synthesis s~eps starting from
substituted naphthalenes (Bull. Soc. Chim. Fr. 3 (1967)
988).
The preparation of ligand systems of the formula 3 and
the conversion to the bridged chiral metallocenes of the
formula K and the isolation of the desired racemic form
is known in principle (AU-A-31 478/89, J. Organomet.
Chem. 342 (1988) 21, EP 0 284 707 and EP 0 320 762). To
this end, the benzoindene derivative of the formula G is
deprotonated using strong bases, such as, for example,
bu~yllithium in an inert solvent and reacked with a
reagent of the formula ~ to give the ligand system of the
formula J. This is subsequently deprotonated u~ing two
equivalents of a strong ba~e, such a~ for example,
butyllithium in an inert solvent and reacted with the
corr~sponding metal tetrahalide, such as, ~or ex~nple,
z.irconium tetrachloride, in a suitable solvent. Suitable
solvents are aliphatic and aromatic solvents, such as/
for example, h~xane and toluene, ethereal solvents, such
as, for example, tetrahydrofuran and diethyl ether, and
halogenated hydrocarbons, such as, for example, methylene
chloride. The racemic and meso forms are separated by
extraction or recrystallization using suitable solvents.
~he derivatization to give the metallocenes of the
formula I can be carried out by methods known from the
literature, for example by reaction with alkylating
- 19 - ~ ~879~
agents, such as, for example, methyllithium (Organometal-
~ lics 9 (1990) 1539, ~. Amer. Chem. Soc. 95 (1973) 6263
and EP 0 277 004).
Examples which may be mentioned of metallocenes which can
be used according to the invention are the following
compounds:
biscyclopentadienylzirconium dichloride,
biscyclopentadienyldimethylzirconium,
biscyclopentadienyldiphenylzirconi~m,
'. 10 biscyclopentadienyldibenzylzirconium,
biscyclopentadienylbistrimethylsilylzirconium,
bis(methylcyclopentadienyl)zirconium dichloride,
bis(l,2-dimethylcyclopentadienyl)zirconium dichloride,
bis(1,3-dimethylcyclopentadienyl)zirconium dichloride,
bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride,
bis(l,2,3-trimethylcyclopentadienyl)zirconium dichloride,
bis(pentamethylcyclopentadienyl)zirconium dichloride,
bi~indenylzirconium dichloride,
diphenylmethylene(9-fluorenyl)(cyclopentadienyl)zirconium
dichloride,
dimethylsil(9 fluorenyl)(cyclopentadienyl)zirconium
. dichloride,
isopropylidene(9-fluorenyl)(cyclopentadienyl)zixconium
dichloride,
dimethyls.ilylbis~1-tetrahydroindenylzirconium dichloride,
dimethyl~ilylbis-1-(2-methyltetrahydroindenyl)zirconium
dichloride,
dimethylsilylbis-1-(2,3,5-trimethylcyclopentadienyl~zir-
- conium dichloride,
dimethylsilylbis-1-(2,4-dimethylcyclopentadienyl)zir-
conium dichloride,
dime~hylsilylbis-l-indenylzirconium dichloride,
dime~hylsilylbis-l-indenylzirconiumdimethyl,
dimethylgermylbis-1-indenylzirconium dichloride,
dimethylsilylbis-1-(2~methylindenyl)zirconi~n dichloride,
dimethylsilylbis-1-(2 methyl-4-isopropylind~nyl)zirconium
. .
~0$7~18
_ 20 -
dichloride,
phenylmethylsilylbis-1-(2-methylindenyl)zirconium di-
chloride,
dimethylsilylbis-1-(2-methyl-4~ethylindenyl)zirconium
dichloride,
ethylenebis~1-(4,7-dimethylindenyl)zirconium dichloride,
phenyl(methyl)silylbis-l-indenylzirconium dichloride,
phenyl(vinyl)silylbis-l-indenylzirconium dichloride,
diphenylsilylbis-l-indenylzirconium dichloride,
dimethylsilylbis(l (2-methyl-4-tert-butylindenyl)zir-
conium dichloride,
methylphenylsilylbis(l-(2-methyl-4-isopropylindenyl)zir-
conium dichloride,
dimethylsilylbis(1-(2-ethyl-4-methylindenyl)zirconium
dichloride,
dimethylsilylbis(1-(2,4-dimethylindenyl)zirconium di-
chloride,
dimethylsilylbis(1-(2-methyl-4-ethylindenyl)dimethylzir-
conium,
dimethylsilylbis(2-methyl-4,6-diisopropylindenyl)zir-
conium dichloride,
dimethylsilylbis(2,4,6-trimethylindenyl)zirconium di-
chloride,
methylphenylsilylbis(2-methyl-4,6-diisopropylindenyl)zir-
conium dichlori.de,1,2-ethanediylbis(2-methyl-4,6-diisopropylindenyl)zi.rco-
nium dichloride
and dimethylsilylbis(2-methyl-4,5-benzoindenyl)zirconium
dichlor.ide.
In the preparation of the catalyst according to the
invention, chiral metallocenes are preferably employed as
a racemate. However, it is also possibl~ to u~e the pure
R or S form. Using these pure stereoisomeric forms an
optically active polymer can be prepaxed. However, the
meso form of the metallocenes should be removed, since
the polymerization-active center (the metal atom~ in
these compounds is no longer chiral due to mirror
2~7~
- - 21 -
symmetry at the central metal and it is therefore impos-
sible to form a highly tactic polymer. If the meso form
is not removed, an atactic polymer i5 formed in addition
to isotactic and syndiotactic polymers. ~or certain
applications soft moldings for example - or for the
preparation of polyethylene grades, this may be entirely
desirable.
The present invention furthermore r~lates t~ a process
for the preparation of the catalyst. This is carried out
at a temperature between -10 and ~120C, preferably at
20DC, by reacting the aluminum compound (the insoluble
aluminoxane) with the metallo~ene. The insoluble alumin~n
compound, as a suspension with 1 - 40% by weight, prefer-
ably with 15 - 20% by weight, in an inert suspending
agent, such as toluene, n decane, hexane, diesel oil or
dichloromethane, is mixed with the solid metallocene or
a concentrated solution of the metallocene in an inert
solvent, such as toluene, hexane or dichloromethanef or
the aluminum compound, as a fine powder, is mixed with a
solution of the metallocene in an inert solvent, such as
toluene, hexane or dichloromethane. The reaction is
carried out with vigorous mixing, for example by stir-
ring.
The Al : M1 (central metal of the metallocene) molar ratio
~5 is preferably from lO0 1 to 10000 : 1, in particular
from lO0 : 1 to 2000 : 1. However, any other Al : M1 ratio
(aluminum compound : metallocene) can also be achieved
and is covered by the present invention.
The reaction time is generally between 5 and 120 minu~es,
~0 preferably 10 - 30 minutes, under inert conditions.
During the reaction for the preparation of the catalyst,
in particular when metallocen~s are used, changes in th~
color of the reaction mixture occur with absorption
maxima in the visible region, and allow the progr~ss of
- 22 - ~ Q ~ ~ ~ L8
the reaction to be followed.
When the reaction is complete, the supernatant solution
is separated off r for example by filtration or decanta-
tion, and the solid which remains is washed, pre~erably
l to 5 times, with an inert suspending agent, such as
toluene, n-decane, hexane/ diesel oil or dichloromethane.
This washing operation (extraction) serves to remove
soluble constituents in the catalyst formed, in parti-
cular to remove unreacted and thus soluble metallocenes.
It is advantageous, but not necessary, to carry out the
entire process in a pressuxe filter, it also being
possible to use various inert solvents for washing the
solid. The filtrate and the wash liquids are colorless,
irrespective of the metallocene previously employed.
The catalyst prepared in this way can be dried in vacuo
and re-suspended as a powder or still containing traces
of solvent, and, as a suspension in an inert suspending
agent, such as, for example, toluene, hexane, diesel oil
or dichloromethane, is metered into the polymerization
system.
The olefin polymerization catalyst according to the
invention is thus prepared in a separate operat.ion
outside the polymeriæation re~ctor.
~he present invention furthermore relates to a process
for the preparation of an olefin polymer by polymeriza-
tion or copolymeriæation of an olefin of the formula
Ra CH-CH-Rb, in which Ra and Rb are identical or different
and are a hydrogen atom or a hydrocarbon radical having
1 to 14 carbon atoms, or Ra and Rb, together with the
atoms connecting them, can form a ring, at a temperature
of from -60 to 200C, at a pressure of from 0.5 to
100 bar, in solution, in suspension or in the gas phase,
in the presence of a cakalyst, wherein the catalyst used
- 23 - 2~9~8
is the reaction product according to the invention.
The polymerization or copolymerization is carried out in
a known manner in solution, in susp~nsion or in the gas
phase, continuously or batchwise~ in one or more steps,
at a temperature of f rom -60 ~o 200C, preferably from 30
to 80C, particularly preferably from 50 to 80C. ~he
polymerization or copolymerization is performed on
olefins of the formula Ra-CH=CH-Rb. In this formula, Ra
and Rb are identical or dif erent and are a hydrogen atom
or an alkyl radical having 1 tv 14 carbon atoms. However,
Ra and Rb, together with the carbon atoms connecting them,
may also form a ring. ~xamples of such olefins are
ethylene, propylene, 1-butylene, 1-hexene, 4-methyl-1~
pentene, l-octene, norbornene, norbonadiene and 1,4,5,8-
dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene (DMON).
In particular, propylene and ethylene are polymerized or
copolymerized.
As molecular weight regulator and/or to increase the
activity, hydrogen is added if necessary. The overall
pressure in the polymerization system .is from 0.5 to
100 bar. Polymerization is pre~erably carried out in the
pressure range of from 5 to 64 har which is paxticularly
interesting in industry.
The catalyst according to the invention is preferably
used in a cvncentration, based on the transition metal,
of from 10-3 to 10-8, preferably from 10~ to 10-7, mol of
transition metal per dm3 of solvent or per dm3 o~ reactor
volume.
If the polymerization is carried out in suspension or
solution, an inert solvent which i6 customary for the
Ziegler low-pressure process is used. For example, the
process is carried out in an aliphatic or cycloaliphatic
hydrocarbon; examples of these which may be mentioned are
butane, pentane, hexane, heptane, isooctane, cyclohexane
and methylcyclohexane.
~ 24 _ 2 ~ 8 79~8
.
i
It i~ fur-thermore possible to use a benzine or hydrogena-
ted diesel oil fraction. Toluene can also be used. The
polymerization is preferably carried out in the liquid
monomer.
If inert solvents are used, the monomers are metered in
gas or liquid form.
The polymerization can have any desired duration since
the catalyst system to be used according to the invention
only exhibits a slight time-dependent drop in the poly-
merization activity.
Before the catalyst is introduced into the reactor,another alkylaluminum compound, such as, for example,
trimethylaluminum~ triethylaluminum, triisobutylaluminum
or isoprenylaluminum, can additionally be added to the
polymerization system in a concentration of from 1 to
O.001 mmol of Al per kg of reactor contents in order to
render the polymerization system inert (for example to
remove catalyst poisons present in the olefin); the total
amount of additional alkylaluminum compound should reach
a maximum of 10 mol% of Al, prefsrably a maximum of
1 mol% of Al, based on the amount of Al present in the
catalyst.
.
However, the use of further 0ubstances for cakalysis of
the polymerization reaction is fundamentally unnecessary,
ie. the catalyst according to the in~ention can - and
this is preferred - be used as the only catalyst for th~
olefin polymeri~ation.
; The molecular weight of the polymer formed can also be
influenced by changing the polymerization temperature,
periodic changes or a multistep process or the use of a
plurality of metallocenes al50 allowing polymers with a
broad distribution to be prepared.
.
2~87918
- ~5 -
In addition, the polymer molecular weight achieved by
me~ns of the solid cataly6t according to the invention is
determined by the t~pe of metallocene used, by the
aluminum compound and by the Al/M1 ratio.
The process according to the inv~ntion (the c~talyst
according to the invention) is primarily distinguished by
the fact that the undesired reactor deposits are prev~n-
- ted in the polym~rization. A further advantage of the
process is that the polymer mol~cular wei~ht is influ-
enced favorably. In particular in the case of propene
polymerization reactions, the pol~mer molecular weight
can be significantly changed compared with the prior art,
ie. a comparative system comprising the mixture of the
same metallocene and soluble aluminoxane, by using the
catalyst according to the invention. Thus, the achievable
polymer molecular weight can be increased for metal-
locanes which tend to form low molecular weights in the
comparative system, or reduced for metallocenes which
tend to form high molecular weights in the comparative
system.
In addi~ion, the grain morphology of the polymer powd0r
prepared is significantly improved. A narrow partlcle
size distribution is attained, while simultaneous.ly
avoiding a coarse component > 1500 ~m and a fine com-
ponent c 100 ~m.
The examples below are itended to illustrate the inven-
tion in greater detail:
All glass equipment was h~ated in vacuo and flushed with
argon. All operations were carried out in Schlenk vessels
with the exclusion of moisture and oxygen. The solvents
used were all freshly distilled over Na/K alloy under
argon and stored in Schlenk vessels.
- 26 - ~087~1~
The ~l/CH3 ratio in the aluminoxan~ wa~ determined by
decomposing the s~nple using ~2SO,, and determining the
volume of the resultant hydrolysis g~se~ under ~tandard
conditions and by compl~xometric titxation of the alumi~
num in the then-dissolved sample by ~he Schwarzenbach
method.
The polymer melting poînts indicated were taXen from a
DSC measurement for the 2nd melting (10/min).
~ or the experiments with the insoluble aluminum compound
(methylaluminoxane), referred to as P-M~O below, an
approximately 17% strength by weight suspension in
toluene, containing 86 mg of Al/ml according to aluminum
determination, was prepared. Analysis of this batch, used
below, gave an Al : CH3 molar ratio of 1 : 0.97.
Toluene soluble methylaluminoxane was employed as a 10%
strength toluene solution for the comparative examples
and contained 36 mg of Al/ml according to aluminum
determination. The mean degree of oligomerization accord-
ing to freezing point depression in benzene was n = 20.
~n Al : CH3 ratio of 1 : 1.55 was determined for the
toluene-soluhle methylaluminoxane.
Example 1:
8.7 ml of the suspension of the P-MAO in toluene are
introduced into a G3 Schlenk frit under axgon and ~
tered. The solid which remains is resuspended in 20 ml of
an aromatic-free, inert diesel oil (boiling point 100 to
12GC). 0.5 ml of a 1/500 molar solution of zirconocene
dichloride (biscyclopentadieneylzirconium dichloride) in
absolute -toluene is metered into this suspension, and the
mixture is stirred at 30C for 1/4 hour. The mixture is
subsequently filtered, and the solid which remains is
washed with 20 ml of diesel oil and resuspended in 20 ml
of diesel oil for the pol~merization.
- 27 _ 2~791~
Polymeriæation
A dry 1.5 dm3 stirred reactor is flushed with nitrogen in
-order to remove the oxygen and filled with 0.9 dm3 of an
inert diesel oil (boiling ~oint 100-120C). ~he reactor
is flushed with ethylene and heated to and held at 70C,
and the catalyst suspension is metered in at an ethylene
pressure of 7 bar without introduction of additional
activator. After 2 hours, the pressure in the reactor is
released, and the polymer is filtered off from the
-10 suspension and dried in a vacuum d~ying cabinet fQr 12
hours, giving 49.5 g of polyethylene having a viscosity
number of 400 cm3/g and a bulk density of 0.120 kg/dm30
The reactor shows no deposits on reactor walls or
stirrer.
Comparative Example 1
The polymerization from Example 1 is repeated with the
difference that the catalysk used is 0.029 mg of zir-
;conocene dichloride dissolved in a 10% streng~h by weight
solution of methylaluminoxane in toluene (12 mmol Al).
Under otherwise identical conditions, 40 g of poly~thyl-
ene hav.ing a viscosity number of 3ao cm3/g and a bulk
density o~ 0.060 kg/cm3 are obtained. Aftex the reactor is
opened, a deposit 1 mm in thic]cness is visible over all
the reactor walls and stirrer.
Comparative Example 2
;
The polymerization from Comparative Example 1 is repeated
with the difference that 40 ml of the toluene solution
which is supernatant in the case of P-MAO i5 employed
instead of the 10% strength by weight me~hylaluminoxane
solution. However, under oth~rwise identical conditions
no polymerization occurs.
2087 ) L 8
- 28 -
Example 2
The catalyst preparation from Example 1 is repeated with
the difference that the washing is carried out not with
diesel oil (boiling point 100 - 120GC) but instead with
anhydrous hexane. The catalyst is subsequently dried for
2 hours at 10-3 mbar and 30C, giving 1.50 g of a free-
flowing powder. Analysis shows 44.4% by weight of Al and
49 ppm of Zr.
1400 rng of the dry catalyst are mixed with 80 g of
polystyren~ powder as a stirring aid, and the polymeriza-
tion is carried out in a 1.5 dm3 reactor wi$h a paddle
stirrer for 2 hours at 70C and 7 bar of ethylene. After
the pressure in the reactor has been released, 122 g of
powder are removed, giving, after extracti.on with boiling
toluene, 42 g of a polyethylene having a viscosity number
of 455 cm3/g.
Example 3
20 ml of a suspension of P-MAO are introduced into ~ G3
Schlenk frit under argon and filtered. The solid which
remains is resuspended in 40 ml of an aromat:ic-free,
inert diesel oil (boiling point 100 to 1.20C). 5 mg of
rac-dimethylsilylbis-l (2-methylindenyl)zi.rconium di
chloride are dissolved in a little toluene and metered in
under argon. After 15 minutes, the solukion is filtered,
and the solid is washed with diesel oil and then resus-
p~nded in 20 ml of diesel oil.
Polymerization
A dry, nitrogen-flushed 16 ~m3 reactor is filled with
10 ~m3 of propylene and held at 30~C. After 15 minutes,
the catalyst suspension is metered via a pressure lock
without further addition of activator On commencement of
~7~ ~
- 29 -
the polymerization, the internal reactor temperatur~ ie
increased to the polymerization temperature of 70 DC at
10/min by additional supply of heat and is subsequently
kept at this temperature by cooling. After a polymeriza-
tion time of 1 hour, -the polymerization is terminated by
addition of ispopropanol, the pressure in the raactor is
released and the reactor is opened. The reactor wall and
the stirrer are completely free of deposits. Vacuum
drying of the product gives 0.37 kg of free-flowing
polypropylene powder having a viscosity number of 154
cm3/g and a melting point (DSC) of 143.1 C. The mean
particle diameter d50, measured by screen analysis, is 450
~m.
Comparative Example 3
To prepare the catalyst, 5.2 mg of rac-dimethylsilylbis~
1-(2-methylindenyl)zirconium dichloride are dissol~ed in
20 cm3 of a toluene solution of methylaluminoxane (corre-
sponding ko 27 mmol of Al) and preactivated by ~tanding
for 15 minutes (cf. EP-A 302 424).
In parallel, a dry 16 dm3 reactor is flushed with nikrogen
and filled with 10 dm3 liquid propene. 30 cm3 of the
toluene solution of methylaluminoxane (corre~ponding to
~O mmol of Al) are introduced into this reactor and
stirred at 30~C for 15 minutes. The catalyst solution is
then introduced into the reactor, and the polymerization
system is heated to the polymerization temperature ~ of
70C (10C/min) by supply of heat and kept at this
temperature for 1 hour by cooling. The polymerization is
then terminated by addition of 5 ml of isopropanol, the
pressure in the reactor is released and the reactor is
opened. A continuous deposit of 3 mm in thickness is
apparent. Vacuum drying of the product gives 1.3 kg of
polypropylene having a viscosity number of 151 cm3/g and
a melting point (DSC) of 145DC. The mean paxticle
diameter d50, measured by screen analysis, is 350 ~m.
~879~ 8
- 30 -
Example 4
The procedure is as described in Example 3, with the
difference that the metallocene used is 5.1 mg of rac-
dimethylsilylbis-1-(2-methyl-4-ethylindenyl)zirCOnium
dichloride. The reactor is free from deposits on walls
and stirrer. Vacuum drying of the product gives 0.33 kg
of free-flowing polypropylene powder having a viscosity
number of 184 cm3g, M~ = 1.91 ~ 105 g/mol, M~/M~ = 2.3 and
a melting point (DSC) of 142.0C. The mean particle dia-
meter d50, measured by screen analysis, is b50 ~ml and theproportion of fine particles (< 100 ~m) ls 0.5~ by
weight.
Comparative Example 4
The procedure is as described in Comparative Example 3,
with the difference that the metallocene used is 4O4 mg
of rac-dimethylsilylbis-l-t2-methyl-4-ethylindenyl)zirco-
nium dichloride. After the polymerization, a continuous
deposit 1 mm in thickness is apparent. Vacuum drying of
the product gives 1.1 kg of polypropylene having a
viscosity number of 113 cm3/g~ M~ = 1.02 x 105 g/mol, M~/M~
= 2.2 and a melting point (DSC) of 145.1C. The mean
particle diameter d50, measured by screen analysis, is
3000 ~m, and the proportion of fine particles (< 100 ~m)
i~ 1.2~ by weight.
Example 5
The procedure is described in Example 3, with the dif
ference that the metallocene used is 5.0 mg of rac-
dimethylsilylbis-1-(2-methyl-4-i-propylindenyl)zirconium
dichloride. The reactor is free from deposits on walls
and stirrer. Vacuum drying of the product gives 0.32 kg
of free-flowing polypropylene powder having a viscosity
2~7~8
- 31 -
number of 223 cm3/g, M~ = 2.55 x 105 g/mol, M~/M~ = 2.5 and
a melting point (DSC) of 146.3C. The mean paxticle dia-
me~er dSo, measuxed by scr~en analysis/ is 650 ~m and the
proportion of fine particles (< 100 ~m) is 0.5~ by
weight.
Comparative Example 5
The procedure is as described in Comparative Example 3
with the difference that the metallocene used is 3.3 mg
of rac-dimethylsilylhis-1-(2 methyl-4-i-propyl.indenyl)-
zirconium dichloride. After the polymerization, a con-
tinuous deposit 1 mm in thickness is apparent. Vacuum
drying of the product gives 1.4 kg of polypropylene
having a viscosity number of 165 cm3/g, N~ = 1.45 x 105
g/mol, MW/M~ = 2.2 and a melting point (DSC) of 149.6 C.
The mean particle diameter dSo, measured by screen
analysis, is 3000 ~m and the proportion of fine particles
(~ lOO~m3 is 2.2% by weight.
Example 6
The procedure is as described in Example 3, with the
difference that the metallocelle used is 30.4 mg of
diphenylmekhylene(9-fluorenyl)(cyclopentadienyl)zirconium
dichloride. The polymerization is carried out as des-
cribed above, but at a polymerization temperature T of
50C. The reactor is free from deposits on walls and
stirrer. Vacuum drying of the product gives 0.31 kg o
free-flowing syndiotactic polypropylene powd~r having a
viscosity number of 334 cm3/g, M~ = 3.13 x 105 g/moll M~/M~
= 2.2 and a melting point (DSC3 of 119.5C. l'he ~ean
particle diameter d50, measurad by screen analysis, is 250
~m.
~ 0 8 r7 9 ~IL 8
- 32 -
Comparative Example 6
The procedure is as described in Comparative Example 3,
with the dif~erence that the metallocene is 9.4 mg of
diphenylmethylene(9-fluorenyl)(cyclopentadienyl)zirconium
dichloride. After the polymerization, a continuous
deposit 2 mm in thickness is apparent. Vacuum drying of
the product gives 0.2 kg o~ syndiotactic polypropylene
- having a viscosity number of 502 cm3/g~ M~ - 4.97 x 105
g/mol, M~/M~= 2.2 and a melting point (~SC) of 134.1C.
~he mean particle diameter d50, measured by screen
analysis, is 2500 ~m.
Example of the preparation of insoluble MAO (P-MAO)
Example 7
The solids component (P-MAO) is removed from 5000 ml of
a commercial solution of 10% strength by weight MAO in
toluene, obtained from Schering/Bergkamen, by sedimenta~
tion and filtration under inert conditions. This solid
content varies from batch to batch since the solid
component is frequently removed as undesired due to the
filling method used. The solid content of this batch is
calculated at 7~ by weight of P-MAO, based on the MAO
content of the solution. This solid remaining is washed
twice with 100 ml of toluene and once with 100 ml of
;~ hexane. The solid is subsequently dried in vacuo to
constant weight, leaving 35 g of pulv~rulent P-MAO.
Determination of the aluminum content in ~he solid ga~e
a content of 44.9% by weight of Al in the solid and a
Al : CH3 molar ratio of 1: 0.95.
8.88 g of the dried P-M~O are suspended in 50 ml of
toluene, and 79 mg of rac-dimethylsilylbis-1-(2-methyl-
indenyl)~irconium dichloride, dissolved in 50 ml of
toluene, are slowly added dropwise with stirring. The
suspension is subsequently stirred at 80~C for one hour.
~7~8
- 33 -
The suspension is filter~d at room temperature and washed
wi~h hexane. The filtrate is colorless. Drying in vacuo
leaves a pink, free-flowing powder.
Polymerization
A dry nitro~en-flushed 16 dm3 reactor is filled with
10 dm3 of propylene and held at 30C. 24 mmol of a
20% strength solution of triisobutylaluminum (TIBA) in a
diesel oil are metered in via a pressure lock in order to
render the system inert. ~ter 15 minutes, 0.84 g of the
dried catalyst, suspended in 50 ml of hexane, are metered
in via the pressure lock. On commencement of the poly-
merization, the internal reactor temperature is increased
to the polymerization tempera~ure of 70C at lO~C/min by
additional supply of heat and sub~equently regulated at
~his temperature by cooling. After a polymerization time
of 1 hour, the polymerization is terminated by addition
of isopropanol, the pressure in the reactor i.s relea~ed
and the reac~or is opened. The reactor wall and stirrer
are completely free from deposits. Vacuum drying of the
product give~ 0.25 kg of free-flowing polypropylene
powder having a viscosity number of 187 cm3/g and a
melting point (DSC) o 1~7.3 C.
