Note: Descriptions are shown in the official language in which they were submitted.
211~3~3
HOECHST AKTIENGESELLSCHAFT HOE 92/F 407 Dr.DA/-
,~.,
- Process for the preparation of polyolefin waxes
:~
The present invention relates to a proceB~ for the
preparation of polyolefin waxes having a low residual a3h
5 content. ~
., ' "~ .
Polyolefin waxes, in particular polyethylene waxes, are
important for a large number of applications. In par-
ticular, highly crystalline waxes are attracting increas-
! ing interest for mixing with abrasion-re~istant printing
inks, for the matting of paints and for the preparation
of emulsifiable waxes for cleaning agents.
Processes for the preparation of polyolefin waxes at
temperatures above 100C in solution in a high-boiling
hydrocarbon are known (cf. British Patent No. 1,311,013
and U.S. Patent 3,951,935). A suspen~ion polymerization
at temperatures below the wax melting point is unsuccess-
ful owing to the high solubility and/or the good ~welling
capacity of these products.
It was found that waxes are soluble only to a negliqible
extent, if at all, in low-boiling hydrocarbon~, in
particular propane, and consequently a ~uspension process -
is also pos~ible for semicrystalline waxes (cf. German ~-~
Patent Application No. 4,217,378). this suspension polymerization
process i8 economically advantageous compared with the
solution process, owing to the simpler separation of the
suspending agent and the lower viscosity of the system.
.
A major problem in the suspension polymerization, in
particular with the u~e of soluble catalyst ~y~tems, is
the build-up of wall deposits, which hinders the jacket
30 cooling of the reactors. Particularly when the ratio of ~ -
reactor surface area to reactor volume becomes more
disadvantageous through the construction of larger
reactors, uncontrollable heating of the polymerization
` `` ~1~13~3
~ system may occur a~ a re~ult of the prevention of heat
- tran~fex.
It was therefore the object to find a polymerization
process in which polyolefin waxe~ can be prepared without
the disadvantages de~cribed, using metallocene catalysts.
~,,
It was found that, in the suspension polymerization of
ethylene and other olef in8 in propane u~ing metallocene
catalyst systems, cooling of the reactor can be carried
ollt by condensation of vapor ("evaporative cooling"), and
that reactor deposits are avoided as a result.
The invention thus relates to a proces~ for the prepara-
tion of a polyolefin wax by polymerization or copolymer-
izatin of olefinæ or diolefins at a temperature of -40 to
100C, at a pressure of 0.5 to 120 bar, in 6uspension and
in the presence of a catalyst comprising a metallocene
and a cocatalyst, wherein the metallocene i6 a compound
of the formula I
R1 R3
/~
R 2 R 4 :~
in which M1 i8 a metal of group IVb, Vb or VIb of the
Periodic ~able of Elements,
20 R' and R2 are identical or different and are a hydrogen ~ ~-
atom, a Cl-C10-alkyl group, a C,-C,0-alkoxy group, a C6-C,0-
aryl group, a C6-C,0-aryloxy group, a C2-C,0-alkenyl group, -~
a C,-C40-arylalkyl group, a C7-C40-alkylaryl group, a C~-C,0-
arylalkenyl group or a halogen atom and
R3 and R4 are identical or different and are a mononuclear
or polynuclear hydrocarbon radical which may form a -~
sandwich structure with the central atom Ml,
low-boiling hydrocarbons having 3 or 4 carbon atoms or
low-boiling halogenated hydrocarbonæ are used aæ
suspending agents and the heat of reaction is removed by
evaporative cooling. - ~
--.:
:':
`"'1 ` ~ ~ ', ~
3~3
- 3 -
In the process according to the invention, the monomers
used are olefins, diolefins and other un~aturated hydro-
carbons having 2 to 18 carbon atom~. Such monomers are
-~ cyclic, polycyclic, linear or branched unsaturated
hydrocarbons. Examples of these are ethylene, propylene,
;~1 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-
pentene, ~tyrene or cyclic olefins, such as cyclopentene,
cyclohexene, norbornene, 1,4,5,8-dimethano-
1,2,3,4,4a,5,8,8a-octahydronaphthalene (DMON) and their
structural derivatives, as well as diolefins, such as
norbornadiene, 1,3-butadiene, 1,4-pentadiene, 1,4- or
1,5-hexadiene, 1,7-octadiene or 1,3- or 1,5-cycloocta-
diene. The polymerization of ethylene or propylene and
the copolymerization of ethylene or propylene with an
olefin having 3 to 10 carbon atoms is preferred, and
particularly preferred copolymer waxes are ethylene/
propylene, ethylene/l-butene and ethylene/l-hexene
polymer waxes and ethylene/propylene/1-butene terpolymer
waxes.
. '~
The polymerization is carried out in the presence of a
metallocene catalyst system. ~ ;
,,~
Suitable highly active metallocene catalyst systems for
the preparation of polyolefin waxes in low boilers ~ `~
comprise a metallocene and a cocatalyst.
, ~.
The metallocene is a compound of the formula I
R1 / R~
\ ~
' / \
R2 R~
in which Ml is a metal of group IVb, Vb or VIb of the
Periodic Table of Elements,
Rl and R2 are identical or different and are a hydrogen
atom, a Cl-ClO-alkyl group, a Cl-ClO-alkoxy group, a C~-Cl0-
aryl group, a C6-Cl0-aryloxy group, a C2-Cl0-alkenyl group,
a C7-C,O-arylalkyl group, a C,-C,0-alkylaryl group, a
~1113~3
. - 4 -
. C5-C40-arylalkenyl group or a halogen atom and
R3 and R' are identical or differ~nt and are a mononuclear
or polynuclear hydrocarbon radical which may form a
san~wich structure with the central atom Ml.
The formula I also embraces compounds of the formula Ia
~ R~
and of the formula Ib :~
R6
( CR ~ ~ R 1 2 )m
R13 (Ib)
C R ~ ! R ~ 2 ~
~ . ' ."
R 9 R 9
. .~
In the formulae Ia and Ib, Ml is a metal of group IVb, Vb ;~
or VIb of the Periodic Table of Element~, for example .~ :
titanium, zirconium, hafnium, vanadium, niobium, tan~
10 talum, chromium, molybdenum and tungsten, preferably :
titanium, zirconium and hafnium.
'~
~ 5 - 2~3 63
R' and R2 are identical or different and are a hydrogen
atom, a C,-C,0-alkyl group, preferably a C,-C3-alkyl group,
a C~-C~0-alkoxy group, preferably a C,-C3-alkoxy group, a
C6-C,0-aryl group, preferably a Cc-C8-aryl group, a C6-C,0-
aryloxy group, preferably a C6-C8-aryloxy qroup, a C2-C,0-
alkenyl group, preferably a C2-C~-alkenyl group, a C7-C40-
arylalkyl group, preferably a C~-C~0-arylalkyl group, a C7-
C,0-alkylaryl group, preferably a C~-C~2-alkylaryl group,
a Ca-C40-arylalkenyl group, preferably a C8-C,2-arylalkenyl
group, or a halogen atom, preferably chlorine or methyl.
R3 and R4 are identical or different and are a mononuclear
or polynuclear hydrocarbon radical which may form a
sandwich structure with the central atom Ml. R3 and R'
are preferably cyclopentadienyl, indenyl, tetrahydro-
indenyl, benzoindenyl or fluorenyl, it being po~sible forthe parent structures to carry additional substituents or
to be bridged with one another.
R5, R6~ R7~ R~ R9 and Rl are identical or different and
are a hydrogen atom, a halogen atom, preferably a fluor-
ine, chlorine or bromine atom, a Cl-Cl0-alkyl group,
preferably a C,-C,-alkyl group, a C6-C~0-aryl group,
preferably a C6-C8-aryl group, a C,-C,0-alkoxy group,
preferably a C,-C3-alkoxy group, or an -NRl'2, -SRl',
-oSiRl43, -SiRl'3 or -PR'~2 radical in which Rl4 i8 a C,-ClO-
alkyl group, preferably a Cl-C3-alkyl group, or a Cc-C
aryl group, preferably a C,-C8-aryl group, or, in the ca~e
of Si- or P-containing radicals, also a halogen atom,
preferably a chlorine atom, or two adjacent radicals R5,
R6, R', R8, R9 or Rl each form a ring with the carbon
atoms linking them. Particularly preferred ligands are
the substituted compounds of the parent structures
indenyl, tetrahydroindenyl, benzoindenyl, fluorenyl and
cyclopentadienyl.
Rl3 i8
`~!3
:4
.
- 6 _ 2~363
.. ~ ,
R15 ~5 R15 R15 R15
2__1 2 12_ --M2_ CR172--o_1,J2_o_
l 16l ~ 6 l 16l 16 1 1 G
~.
:
R 15 R 15R ~ S R 15
-I- -o-I2_ 12 o lZ~
1 1 6 R 16 l ~ o I 16
=BR'5, =AlRls, -Ge-, -Sn-, -0-, -S-, ~S0, -S02, ~NR15, ~C0,
-PR1s or =P(o)Rl5, in which R'5, Rl6 and R" are identical or
different and are a hydrogen atom, a halogen atom, a C,~
C30-alkyl group, preferably a C,-C4-alkyl group, in
particular a methyl group, a C1-C10-fluoroalkyl group,
preferably a CF3 group, a C6-C10-fluoroaryl group,
preferably a pentafluorophenyl group, a C6-C,0-aryl group,
preferably a C6-C6-aryl group, a C,-C,0-alkoxy group,
preferably a C1-C4-alkoxy group, in paxticular a methoxy
group, a C2-C10-alkenyl group, preferably a C2-C4-alkenyl
group, a C7-C40-arylalkyl group, preferably a C,-C10-aryl-
alkyl qroup, a C8-C40-arylalkenyl group, preferably a Ca~
Cl2-arylalkenyl group, or a C7-C40-alkylaryl group,
preferably a C~-C~2-alkylaryl group, or
Rls and Rls or Rl5 and Rl', together with the atoms linking
them, each form a ring.
. .
M2 is 3ili~0n ~ germanium or tin, preferably sili~on and
germanium.
Rl3 iB preferably -CRlsR'6, -SiRlsR16, -GeR'sRl6, -0-, -S-,
20 eS0, -PRls or -P(O)R1s. ~-
Rll and Rl2 are identical or different and have the meaning
stated for Rls.
m and n are identical or different and are zero, 1 or 2, :~
preferably zero or 1, m plUB n being zero, 1 or 2, : ~
: . . -
- -
3 ~3
~ - 7 -
-;~
. preferably zero or 1.
Examples of preferred metallocene~ are: -
bis(cyclopentadienyl)zirconium dichloride,
s! bi~(methylcyclopentadienyl)zirconium dichloride, --
bis(n-butylcyclopentadienyl)zirconium dichloride,
bis(i-butylcyclopentadienyl)zirconium dichloride,
bis(alkylcyclopentadienyl)zirconium dichloride, ~ :
bis(l,2-dimethylcyclopentadienyl)zirconium dichloride,
bis(l,3-dimethylcyclopentadienyl)zirconium dichloride,
bis(l,2,4-trimethylcyclopentadienyl)zirconium dichloride,
bis(l,2,3-trimethylcyclopentadienyl)zirconium dichloride,
bis(indenyl)zirconium dichloride,
bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride, --
bis(l-methylindenyl)zirconium dichloride,
bis(2-methylindenyl)zirconium dichloride,
bis(4-methylindenyl)zirconium dichloride,
bis(5-methylindenyl)zirconium dichloride,
bis(2-methyl-4,6-di-i-propyl-indenyl)zirconium
dichloride,
bis(alkylindenyl)zirconium dichloride,
bis(cyclopentadienyl)zirconiumdimethyl and
bis(cyclopentadienyl)zirconiumdibenzyl,
- and further preferred metallocenes:
dialkylsilylbis(indenyl)zirconium dichloride,
alkylalkylenebis(indenyl)zirconium dichloride,
alkylenebis(indenyl)zirconium dichloride,
diarylalkenylbis~indenyl)zirconium dichloride,
alkylenebis(indenyl)hafnium dichloride,
diarylsilylbis~indenyl)zirconium dichloride,
(aryl)(alkyl)bis(indenyl)zirconium dichloride,
dialkylgermylbis(indenyl)zirconium dichloride,
(alkyl)(alkenyl)silylbis(indenyl)zirconium dicbloride,
(aryl)(alkenyl)silylbis(indenyl)zirconium dichloride,
dimethylsilylbis(indenyl)zirconium dichloride,
ethylenebis(indenyl)zirconium dichloride,
diphenylsilylbis(indenyl)zirconium dichloride,
3 ~ S~ .
~.i dimethylgermylbis(indenyl~zirconium dichloride,
~ bis(pentamethylcyclopentadienyl)zirconium dichloride, ~-~
~ dimethyl~ilyl-bi6(l-tetrahydroindenyl)zirconium
;~ dichloride,
;~ S ethylene-bis(1-tetrahydroindenyl)zirconium dichloride, -- ~:
dimethylsilyl-bi~-1-(2-methyltetrahydroindenyl)zirconium ~-~
. dichloride,
ethylene-bis-1-(2-methyl-tetrahydroindenyl)zirconium
dichloride, ~ :
dimethylsilyl-bis-1-(2,3,5-trimethylcyclopentadienyl)~
zirconium dichloride, ~:
dimethylsilyl-bis-1-(2,4-dimethylcyclopentadienyl)-
zirconium dichloride,
ethylene-bis(l-indenyl)zirconium dichloride,
dimethylsilyl-bis(1-indenyl)zirconium dichloride,
diphenylsilyl-bis(l-indenyl)zirconium dichloride,
dimethylsilyl-bi~ indenyl)zirconiumdimethyl,
dimethylsilyl-bis-1-(2-methyl-indenyl)zirconium
dichloride, .
phenylmethylsilyl-bis-1-(2-methyl-indenyl)zirconium
dichloride, :-~
dimethylsilyl-bis-1-(2-methyl-4-ethylindenyl)zirconium -:
dichloride,
dimethylsilyl-bis-1-(2-methyl-4-i-propylindenyl)zirconium -~
dichloride and
ethylene-bis-1-(4,7-dimethyl-indenyl)zirconium : -
dichloride,
and other metallocenes which can be used:
diphenylmethylene(9-fluorenyl)(cyclopentadienyl)zirconium
30 dichloride, :
dimethylsilyl(9-fluorenyl)(cyclopentadienyl)zirconium
dichloride,
isopropylidene(9-fluorenyl)(cyclopentadienyl)zirconium
dichloride and ~ :-
isopropylidene(l-indenyl)(cyclopentadienyl)zirconium
dichloride. ~ -~
2~113~3
.,~ g ~ ~,
~Ethylenebis~indenyl)zirconium dichloride, bi6(indenyl)-
:-~zirconium dichloride, bis(4,5,6,7-tetrahydroindenyl~-
`~,zirconium dichloride, bTts(cyclopentadienyl)zirconium-
dimethyl, bi6(methylcyclopentadienyl)zirconium di-
chloride, bis~n-butylcyclopentadienyl)zirconium di-
chloride and bis(cyclopentadienyl)zirconium dichloride ~ -
are particularly preferably used.
In principle, any compound which, owing to it~ Lewis
acidity, i8 capable of converting the neutral metallocene
into a cation and stabilizing it ("labile coordination")
is sllitable as a cocataly~t. In addition, the cocatalyst
or the anion formed from it should not undergo any
further reactions with the metallocene cation.
The cocatalyst of the catalyst to be used according to
the invention is preferably an aluminoxane or another
organoaluminum compound. The aluminoxane i8 a compound
of the formula IIa for the linear type and/or of the
formula IIb for the cyclic type
R l ~ l _ ", _ ~ R I ~
A I-- t A I--O ~ A ~ ( I I o )
~ l l b )
In these formulae, R16' is a C1-C6-alkyl group, preferably
20 methyl, ethyl, n-butyl or isobutyl, in particular methyl -~
or butyl, and p is an integer from 4 to 30, preferably 10
to 20, it being possible for radicals RlB also to be
different. Methylaluminoxane and methylbutylalllm;noxane
' ~
: . :
:~ 2~ 13~3
1 0
.,"~ .... ..
having a methyl : butyl ratio of 100 : 1 to 1 : 1 are
particularly preferred, butyl being intended to mean n-
butyl or isobutyl or n-butyl/isobutyl mixtures and the
radicals having any distribution, preferably a random
distribution.
,~' :
A further possibility is the u~e of ~upported aluminox-
anes by, for example, suspending the carrier under inert ;
conditions in a solution of at lea~t one alkylaluminum
and reacting this suspen~ion with water.
: : ::
The catalyst to be used according to the invention can be
prepared by reacting the transition metal compound with
the organoaluminum compound by various methods~
!. 1) The organoaluminum compound is combined, in a suitable
solvent, such as, for example, pentane, hexane, heptane,
toluene or dichloromethane, with the transition metal
compound at a temperature of -20 to +120C, preferably
at -10 to 40C, by thorough mlxing, for example by
stirring. The molar ratio Al : M1 is 1 : 1 to -~
10,000 : 1, preferably 10 : 1 to 2,000 : 1, and the
reaction time is 5 to 120 minutes, preferably 10 to 30
minutes, at an aluminum concentration of more than
0.01 mol/dm3, preferably more than 0.1 mol/dm3, under
inert gas.
. .
2) An insoluble or supported aluminoxane, in the form of
a suspension having a content of 1 to 40% by weight,
preferably 5 to 20% by weight, in an aliphatic, inert
suspending agent, such as n-decane, hexane, heptane or
diesel oil, is reacted with a finely milled transition
metal compound or its ~olution in an inert solvent, ~uch
as toluene, hexane, heptane or dichloromethane, in a
molar ratio Al : M1 of 1 : 1 to 10,000 : 1, preferably
10 : 1 to 2,000 : 1, at a temperature of -20 to ~120C,
preferably -20 to 40C, for a reaction time of 5 to 120
minutes, preferably lQ to 60 minutes, with thorough
mixing.
~ :
:J ~
~i~13~3
The catalyst thus prepared i8 either used as a suspension
directly for the polymerization or separated off by
filtration or decanting and washed with an inert suspend-
ing agent, such as toluene, n-decane, hexane, heptane,
diesel oil or dichloromethane. After such a wa~h, it can
be metered into the polymerization system either as a
powder after drying in vacuo or in solvent-moist form
after resuspen~ion as a suspension in an inert suspending
agent, such as, for example, toluene, hexane, heptane,
diesel oil or dichloromethane.
The catalyst prepared according to 1) or 2) may also be
1 used in prepolymerized form, or the metallocene can be
;~ applied to a carrier before being used.
.!,
One of the olefins to be polymerized is preferably used
for the prepolymerization. Suitable carriers are, for
example, silica gel, alumina, solid aluminoxane or other
organic or inorganic carriers. A polyolefin carrier is
also suitable.
Instead of the organoaluminum compounds, compounds of the
formulae Rl9~NH4~BR2" R19~PH, BR20~ R19CBR~0 or BR20
also be used as cocatalysts. In these formulae, x is a
number from 1 to 4, the radicals R19 are identical or
different, preferably identical, and are C~-C1O-alkyl or
C6-Cl~-aryl, or two radicals Rl9, together with the atom
linking them, form a ring, and the radicals R20 are
identical or different, preferably identical, and are C6-
Cl~-aryl which may be substituted by alkyl, haloalkyl or
fluorine. In particular, R19 i8 ethyl, propyl, butyl or
phenyl and R20 is phenyl, pentafluorophenyl, 3,5-bis-
30 trifluoromethylphenyl, mesityl, xylyl or tolyl. -
These cocataly6ts are particularly suitable in combina-
¦ tion with metallocenes of the formula I when Rl and R' are
a Cl-C1O-alkyl group or an aryl or benzyl group, prefer-
ably a methyl group. The derivatization to give the
metallocenes of the formula I can be carried out by
' ~ ~ ~
: :
2 ~ 3 :::
- 12
methods known from the literature, for example by reac- -~
tion with alkylating agents, ~uch a~ methyllithium (cf. -~
~ Organometallic~ 9 ~1990) 1539; J. Am. Chem. Soc. 95
-~, (1973) 6263).
. ~. .,
3 5 When the abovementioned cocatalysts are u~ed, the actual ~-~
(active) polymerization catalygt comprises the reaction
~;, product of metallocene and of one of the stated com- ~ ;~
pounds. This reaction product i8 therefore first prefer-
ably prepared outside the polymerization reactor in a
10 separate step using a suitable solvent, such as, for
~17 example, toluene.
The transition metal component is used in a concentration
of, based on the transition metal, 10-3 to 10-7, preferably ; -
, 10-4 to 10-6~ mol of Ml per dm3 of solvent- The cocataly3t ~
15 is used in a concentration of, based on the content of ~-
aluminum, 10-5 to 10-1 mol, preferably 10-4 to 10-2 mol, per
dm3 of olvent. In principle, however, higher concentra-
tions are also possible.
,~
~ .
The polymer~zation is carried out as a suspension poly- -~
20 merization with evaporative cooling. -~
Suitable suspending agents are low-boiling hydrocarbons,
such a~, for example, propane, i~obutane or n-butane, or
low-boiling halogenated hydrocarbons, ~uch as, for ~--
example, methylene chloride, and their mixtures with one
25 another or with other suspending agents, such as hexane,
heptane, octane, diesel oils or toluene, or with olefins,
as described above. Furthermore, up to 40% by weight of
the suspending agent may be liguid 012fins. A preferred
main component of the suspending agent i8 propane.
~.
30 The polymerization is carried out at a temperature of 40-
95C, at an olefin partial pressure of 0.5 to 30 bar, at
a hydrogen partial pressure of O to 10 bar, with the
addition (based on Al) of 0.01 to 10 mmol of cocatalyst/ -
dm3 of suspending agent and with a catalyst/cocatalyst
æ ~ :~
~ ' ' .', ~ ' ,,
t'', ~ , ~ . ' ' " ' ~ :. ' ' ' , , . ' `
~ 1 1 1 3 6 3
~ ratio of 1 : 1 to 1 : 1,000.
i-~ The total pressure of the ~y~tem i8 not more than 150% of
the vapor pressure of the suspending agent at the poly-
merization temperature. It i8 preferable to use propane
as a suspending agent at 60-80C and a total pressure of
23 to 48 bar, particularly preferably at 70C and 26 to
39 bar.
I
In order to regulate the molar weight, hydrogen is
additionally introduced or the polymerization temperature
is changed, it also being possible to obtain polymers
having a broad molecular weight distribution by periodic
'''~? changes or a defined multistage process-
For the polymerization, another alkylalllm;num compound,
such as, for example, trimethylaluminum, triethyl-
aluminum, triisobutylaluminum or isoprenylaluminum, mayadditionally be introduced for rendering the polymeriza-
tion system inert, in a concentration of 1 to 0.001 mmol
of Al per kg of reactor content, before the addition of
the catalyst.
:.
20 In addition, the polymer molecular weight achieved in the ; ~-
procesa according to the invention is determined by the
type of metallocene used, by the Al/Zr ratio of the ~`
catalyst system and by the addition and type of further
alkylaluminums.
The polymerization ;is aarried out batchwise or con-
tinuously in one or more stages, and any residence times
can be realized owing to the only slight time-dependent
decrease in the polymerization activity.
For the suspension process with evaporative cooling, the
narrow molecular weight distribution achievable with
metallocene catalyst systems is also advantageous since ~-
it makes it possible to achieve a lower proportion of
volatile oligomers, which may accumulate in the
'~'. '- -'' '.
,
- 14 ~ 1363
condensers during prolonged operation. :::
~3
The polymerization i8 carried out in an apparatus a~ :
shown schematically in the Figure. ~
~ In the Figure, the meaning~ are as follows: ~ :
`: 5 1 Reactor (if neces3ary with stirrer)
~ 2 Separating column/stillhead ~ ~:
:~ 3 Pipeline
3 4 Condenser
'`.~1
~j 5 Pipeline
10 6 Equilibrating vessel
7 Pipeline
8 Pump ::~
9 Pipeline ~-
Valve
15 11 Pipeline : ~ :
12 Valve
13 Feed pipe for monomer~ and hydrogen
14 Feed pipe for suspending agent
15 Feed pipe for cataly~t and cocatalyst :~
20 16 Feed pipe for alkylaluminum or additional cocatalyst ~:
17 Discharge pipe ~:
The polymerization reactor (1) iB equipped with a separa~
ting column (stillhead) (2). From this separating column
a pipeline (3) leads to a condenser (4), which however
25 may also be connected directly to the ~eparating column .
(2). A pipeline (5) leads to an equilibrating vessel (6)
which is connected via a pipeline .(7), a pump (8) and a
pipeline (9) to the reactor (1). Downstream of the pump ~:~
(8), a pipeline (11) leads to the ~eparating column/
stillhead (2). The pipeline (9~ can be ~hut off by a
valve (10) and the pipeline (11) by a valve (12). The
feed pipes (13) and (14) also lead into the reactor (1), ~c:-
the pipe (14) additionally being connected to a feed pipe :~
(15). The reactor (1) can be emptied through the dis~
charge pipe (17). A feed pipe (16) is also connected to
the pipeline (7).
.:"~
~1~13~3
- 15 -
The suspending agent present in the reactor (1) i8 aaused
$ to boil by the heat of polymerization and flows through
-~ the pipeline (3) into the condenser (4), where it is
j! condensed. Low molecular weight product~ are retained in
the separating column (23. The condensed ~u3pendinq
agent i~ fed through the pipeline (5) to the
equilibrating vessel (6), from where it i~ removed
through the pipeline (7) and is recycled by means of the
pump (8) through the pipeline (9) and the valve (10) into
i 10 the reactor (1). Additional activator (alkylaluminum or
cocatalyst) is fed through the pipeline (16) into the
stream of the suspending agent. In the preparation of
low molecular weight product~, some of the suspending
agents can be fed through the pipe (11) and the valve
(12) into the separating column (2) to support there the
recycling of entrained products into the reactor (1).
Monomers and hydrogen are fed into the reactor (1) ~-
through the feed pipe (13), and fresh su~pending agent
through the feed pipe (14). The mixture of cataly~t and
cocatalyst is introduced into the stream of the
suspending agent through the feed pipe (15). The polymer -
wax formed is removed from the reactor (1) through the
discharge pipe (17). -~
: ~
In order to increase the yield, or for a two-stage
process, a second reactor may be arranged downstream of
the suspen3ion discharge (17).
In order to inarease the solids content at the suspension
discharge, the latter can be mounted on a sedimentation
part in the reactor bottom. This reduces the proportion
of monomers dissolved in the suspending agent and the
operating costs for recycling the suspending agent and
maintaining the cocatalyst level in the reactor.
The catalyst can be metered as a solution or in supported
form as a suspension. For preactivation, some of the
cocatalyst (30 to 80 mol %, based on Al) i8 mixed with
the cataly~t at least 10 minutes before metering into the
2111363
~ - 16 -,
reactor or is already part of the supported catalyst.
The cataly~t 601ution thus prepared can be metered into
the reactor either directly or preferably in dilute form
via the feed pipe (14) of the suspending agent.
Y~ 5 In order to regulate the cocatalyst level, the cocatalyst
~l may furthermore be metered separately and together with
further alkylaluminums into the reactor or into the
condenRate return (7).
.
In general, hydrocarbons, such as toluene, heptane,
hexane, pentane, butane or propane, and industrial diesel
oils are suitable as solvents or suspending agentR for
catalyst or cocatalyst.
::
It i8 in general possible to dispense with stirring of
the reactor content since the boiling suspending agent
15 produces good circulation. ~-
Further processing of the suRpension of wax and low
boilers, conventional methods for wax proce~sing can be
used after the pressure has been released.
.--
The polyolefin wax prepared according to the invention is
separated from the suspending agent and dried.
Polyethylene waxes prepared according to the invention ~-
are composed of 100 to 80% by weight, based on the total ~-~
polymer, of ethylene units and 0 to 20% by weight, based
¦ on the total polymer, of units which are derived from ;
another olefin, a diolefin or another unsaturated
hydrocarbon, in particular propylene, l-butene, 2-butene,
4-methyl-1-pentene or l-hexene. They have an average
molecular weight M~ of about 500 to about 50,000,
preferably about 1,000 to about 30,000. The molecular
30 weight distribution (polydispersity) M~/M~ is extremely -~
narrow and is about 1 to 5, preferably 1 to 3. The
melting range of the wax can be adjusted as required from
about 126 to 132C for a homopolymer down to about 80 to
~1
2~13~3
- 17 -
90C by copolymerization.
Polypropylene waxes prepared according to the invention
~;j are composed of 80 to 100, preferably 90 to 100, % by
weight, based on the total polymer, of propylene units
and 0 to 20, preferably 0 to 10, % by weight, based on
~:~ the total polymer, of units which are derived from eth-
., ylene or one of the other olefins described above. Th~y
,~ have an average molecular weight M~ of 1,000 to 50,000 g/
mol, preferably 8,000 to 45,000 g/mol, a polydi~persity
`~ 10 ~,/M~ of 1 to 5, preferably 1 to 3, a melting point of 50
to 160~C, preferably 90 to 160C, a melt viscosity of 100
to 80,000 mPa.s, preferably 120 to 50,000 mPa.s, at 170C
and a random distribution of the comonomer units in the
polymer chain.
~ '
The evaporative cooling require~ a8 high a proportion as
possible of condensable gases in the vapor space and i~
therefore useful only in the case of catalyst systems
which polymerize with very high conversions even at low
ethylene pre~sure. Also advantageous for carrying out
the evaporative cooling is the low hydrogen parti~
pressure which, owing to the good hydrogen re~ponso
characteristics of the metallocene catalysts, i8 required
for achieving the polymer molecular weights typical of -~
waxes.
.
A further advantage of the evaporative cooling is the
avoidance of a reduction in the cooling capacity of the
polymerization reactor through the build-up of wall
depo3its. Furthermore, dispensing with wall cooling
results in reduced deposit formation. The com~ination of
evaporative cooling with back-washing makes it possible
to free the upper part of the reactor continuously or
discontinuously from product particles, with the result
that shutdowns for aleaning the pipelines and condenser
to remove entrained particles can be avoided. The
introduction of back-washing thus permit~ continuous
operation.
-~: ~111363
~ 18 -
A further advantage of this polymerization proc~ss i8 the
;~ high space-time yield which can be realized by the
v efficient evaporative cooling, regardle~s o~ the ~ize of
the polymerization system.
5 The Example~ which follow are intended to illustrate the
invention in detail.
The meanings are as follows:
VN - Viscosity number in cm3~g
MW 3 Weight average molecular determined by
1 10 weight gel permeation ~ -
M~ = Number average molecular ~ ~ chromatography
,; weight
~4, MW/M~ ~ Polydisper~ity J ~ (Numerical data
in g/mol)
15 MV e Melt viscosity, determined using -;~
a rotational viscometer at 140C
BD - Bulk density of the polymer powder in g/dm3
Nelting points, crystallization points, the half-widths
thereof, the enthalpies of fusion and of cry~tallization
20 and the glass transition temperature~ ~T9) were ;~M~
determined by DSC measurements (10C/min heating/coolinq ~-
rate). -
. ~
Examples
All glass apparatuses were heated in vacuo ~nd flu~hed
with argon or nitrogen. All operations were carried out
in the absence of moisture and oxygen in Schlenk vss~els.
The solvents u~ed were each freshly distilled over Na/R
alloy under argon and stored in Schlenk vessels.
The stated polymer melting points are taken from a DSC
measurement for the second melting ~10C~min). The
i~otactic index was determined from FT-IR spectra without
prior extraction of the sample, via the intensity ratio
of the bands at 998 cm~l and 972 cm~', according to
Dechant, "IR-spectroskopische Untersuchungen von Poly-
meren" tIR spectroscopic investigations of polymers],
. .
- 19- 21113~3
.~
Akademie Vlg., Berlin 1972.
:: -
Methylaluminoxane wa~ obtained commercially as a 10~
strength toluene solution and, according to the all~inum
determination, contained 36 mg of Al/cm3. The average
degree of oligomerization according to the freezing point
- depression in ~enzene was n = 20.
:~, ::
The aluminum determination was carried out by complexo-
-~ metric titration according to Schwarzenbach, after
hydrolysis with water and sulfuric acid.
'. . ~
The polymerizations were carried out in an apparatus
similar to that shown in the Figure.
.
Example 1
30 kg of propane and 2.70 kg of propylene and 100 cm3 of ~-
a solution of methylaluminoxane in toluene were intro-
duced into an apparatus according to the Figure h~ving a
100 dm3 vessel and flushed with nitrogen 0.5 b~r
hydrogen and 4 bar ethylene were fed in while stirring at
170 rpm.
At the same time, 35 mg of bis(indenyl)zirconium di-
chloride were dissolved in 100 cm3 of the solution of
methylaluminoxane in toluene and stirring was carried out ~ -
for 15 minutes. -~
~ '
The stirrer in the reactor wa8 switched off and the
polymerization was started by pumping in the catalyst
solution over 10 minutes. The internal temperature of
the reactor increased rapidly and was regulated at 70C
by subseguently feeding in ethylene. The relative
concentration of the gases in the vapor space of the
reactor was monitored with the aid of a gas chromatograph
(GC). Hydrogen and propylene were subsequently metered
in at a con~tant ratio to the ethylene according to GC. ;~
A total pressure of 30 bar was achieved at equilibrium.
~ ~1113~3
The valves (10) and (12) were set 80 that the pump (8)
delivered 10% by volume of the circulation via pipe ~
~- into the ~tillhead (2) of the reactor (1). After a
polymerization tLme of 1 hour, the propane wax ~uspension
5 wa discharged into a proceesing ves~el and the catalyst
; was deactivated by adding isopropanol. After the propanehad been distilled off and the product dried at reduced
pressure, 11.2 kg of copolymer wax h~ving a VN of -;
22 cm3/g~ a melting point (DSC) of 112C and a DSC en-
~1 10 thalpy of fu~ion of 138 J/g were obtained when the
~' processing vessel was opened. The viscosity of the melt
--~i was 1,200 mPa.s at 140C. The propylene content was
`i 4.4 mol % according to '3C-NMR. ~ -~
The experiment was repeated four times. The yield
15 remained constant at about 5% by weight. After the
3 reactor was opened, no wall deposits were found, apart
`~ from finely divided product residues on the bottom.
Comparative Example A ~-
-
Example 1 was repeated, the double jacket of the reactor
being connected to a thermostat ~ystem and pipe t3) and
valves (10) and (12) being closed. The polymerization
was then continued at 30C by adding the catalyst and
thereafter with cooling to an internal reactor
temperature of 70C. Ethylene was continuously metered
in up to a total pressure of 30 bar, and propylene and
hydrogen were added in accordance with the result~ of the
GC measurement.
After 1 hour, 10.5 kg of copolymer wax having a VN of
19 ~m3/g and a melt viscosity of 800 mPa.s at 140C
3C resulted.
The experiment was repeated four times. The dif~erence
between jacket temperature and internal reactor tempera-
ture increa~ed with progressive operating time. After
the reactor had been opened, a cohesive wax depo~it
C ~ ~ Ob _ ~ ~ f ~
;~111363
- 21 -
,~ i
having a thickness of about 0.5 mm was found on the inner
wall of the reactor
; `
.~ Comparative Example B ~;
Example 1 was repeated, the valve (12) remaining closed
during operation.
~ . ~
After the processing vessel had been opened, 11.6 kg of
copolymer wax having a VN of 20 cm3/g and a melt Vi9
cosity of 910 mPa.s at 140C were obtained. The experi-
ment was repeated four times. After the reactor had been
opened, no wall deposits were found, as in 2xample 1.
Loose deposits of a fine material were found in the
reactor stillhead (2) and partly in the pipe (3). The VN
of 18 cm3/g indicated that the deposits were composed
mainly of entrained product and only to a small extent of
oligomer~.
,
.,~
.' ~
: -
