Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE >?JVENTZON
This invention relates to a process for producing long chain branched polymers
comprising repeating units derived from at least one isoolefin monomer and at
least one
allyl halide monomer in a single stage process in solution, suspension or in
the gas phase.
!0 BACKGROUND OF THE INVENTION
Polymers made from allyl chlorides are known. M. Marek ("Makromol. Chem.",
187, (1986) 2337-44) synthesized homopolymets of methallyl chloride in
methylene
chloride with A1C13 or AlBr3 as an initiator. The oily products with Ma of
about 400-
620 g~mol were obtained and the mechanism of reaction was discussed. Allyl
chloride
1S was polymerised with AIBr3 at elevated temperatures (Davideon, E. B., Inr.
Synip.
Macromol. Chem., P~epr., 1969, 1, 3SS; Zil6erman, E. N., Kulikova, A_ E.,
Pinchuk, N.
M., Slonim, I. Y, Mochalova, O. A., Tr. Khim. Khim. Tekhnot., 1971, l, 159,
Chem.
Abstr. 77:165139). Only oligomers weoe t~ceived by this technique.
(Co)-polymers comprising allyl chlorides are known. US-3,299,020 makes a
20 reference that the direct reaction of isobutene with methallyl chloride
initiated with
aluminum halide catalyst in methyl chloride gave a product with very low
molecular
weight, e.g. 6000 glmol. Furthermore, a process is disclosed for the
copolymerization
of isobutene and an allyl halide in methyl chloride using a Ftiedel-Crafts
catalyst
chosen from a group consisting of aluminum chloride, aluminum bromide, boron
25 chloride and stannic chloride. The procedure involved dissolving each
monomer
separately in solution, adding catalyst to the allyl chloride solution, and
subsequently
adnuxing both solutions in a reaction zone. The product contained at least
about 0.5
wt. ~ of chlorine with polymer molecular weight between 80,000 and 200,000
~jmol.
Sadykh-Zade et al. CChem. Abstr. 70, 207$6j) studied the copolymerizstion of
30 isobutene (with and without isoprene in the feed) and methallyl chloride
using A1C13 as
a catalyst.
EP-A1-0 448 627 discloses a catalyst system for cationic (eo)polymerization of
1-olefins. The most preferred 1-olefin is isobutene or feedstock containing
isobutene.
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The catalyst system comprised an organo-aluminum compound RrtAIX~, like
ethylaluminum dichloride, a methallyl chloride, and SnC4, or SnBr~, or TiCia,
or TiBr4.
Two components of the catalyst system were prepared separately and added
simultaneously through the two feed lines to the reactor. When methallyl
chloride was
present in amounts up to 15 wt,°7o with respect to 1-olefin, it could
act as a comonomer
and isobutene polymers containing halogen atoms could be produced.
Conjugated diolefins bearing an allylic halide moiety were utilized in a
direct
synthesis of halobutyl-type polymers (US-5,342,908 and US-5,473,029).
It is further known, that benzyt halides can function as both an Inltlator and
a
monomer ("inime:"), G. Langstein et al_ (IJS 6,156,859) claimed a single stage
process
for producing branched polyisobutene and butyl rubber using vinylben2yl
chloride
andfor isoprenylbenzyl chloride as an inimer and methylaluminoxane (MAO) as a
co-
initiator. However, US 6,156,859 is silent about allyl halides.
The cationic polymerisation of isoolefins is known (set e.g. Ullmanns
Encyclopedia of Industrial Chemistry, Vol. A 23, 1993, pages 288-295) and
leads to
isoolefin-co-polymers, of which isobutene-isoprene co-polymers (butyl rubbers)
art the
mast important ones. On account of their physical properties, the butyl
rubbers and halo-
buryl rubbers produced in this manner arc used in industry, particularly for
the production
of tyre tubes and inner liners for tyres. In this connection, the processing
properties of the
butyl rubbers produced in this manner during compounding, rolling, extrusion
and
caiendering are particularly important. The processing properties are
associated in
particular with a balanced ratio of the green strength of the rubber and to
the stress
relaxation thereof. This can be achieved, for example, by blending
corncsponding
polymers with different molecular weights to form products having a custom-
made, broad
molecular weight distribution. This process is laborious, however.
The direct synthesis of butyl rubbers which exhibit a broad molecular weight
distribution and random long-chain branching and which have the desired
processing
properties can be accomplished, for example, by the copolymerisation of
isobutene with
isoprene in the presence of bifunctiona! monomers such as divinylbenzene, 2,5-
hexadiene
or vinylbentyl chloride. However, one significant disadvantage of this
copolymerisation
is the formation of high proportions of gels in the rubber (see H.-C. Wang,
K.W. Powers,
).V. Fusco, ACS Meeting, May 1989 Paper No. 21, for example).
Another method of Introducing long chain branching occurrences was therefore
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CA 02388739 2002-06-03
introduced, namely the copolymetisation of isobutene and isoprene in the
presence of
mufti-functional branching agents. The latter are to be understood as soluble
polymers
which contain functional groups, and which under the process conditions either
initiate
polymerisation ("grafting from" by tertiary alkyl groups) or react with the
cationic end of
the growing polymer chain (''grafting onto" by reactive double bonds).
Hydrochlotinated
pofy(styrene-co-isoprenes), chlorinated polystyrenes, polyisoprenes or styrene-
butadiene
block copolymers have been mentioned as mufti-functional branching agents (EP-
A1-0
320 263). The resulting polymer mixtures are termed "star branched butyls". A
disadvantage of this proccdurc is the necessity for scparatc, additional
process steps for
the polymerisation or halogenation of the branching agents, The simultaneous
formntion
of linear and branched polymers during polymerisation is a characteristic of
Chic
procedure.
The production of "mufti-arm star" polyisobutenes by the reaction of active
polyisobutene polymers with divinylbenzene is described in Polymer Bull. 31
(1993) 665.
These polyisobutenes arc produced by the "arm-first, core-last" method, which
is
explained in US-5,458.796.
Another possibility for the production of branched butyl rubbers is the use of
mufti-functional initiators, as described in US-5,084,SZZ" This method is also
termed the
"core-first, arm-last" method. This procedure is also burdened with some
disadvantages,
on account of the separate process steps for the production of the mufti-
functional initiator
and for the formation of homopolymers by transfer reactions.
SUMMARY OF THE I1WENTION
The present invention provides a single-stage process for producing long chain
branched polymers comprising repeating units derived from at least one
isoolefin
monomer and at least one allyl halide, wherein the isololcfin(s), the allyl
halides) and
optionally further co-monomers ate potymerised in the presence of an initiator
selected
from the group consisting of alkylalurnoxanes, alkylalutniminium halides
RAAIXj.o, with
each R being independently a Ct-C4o group and each X being independently a
halogen,
or mixtures thereof.
DETAILI~D DESCRIPT'iON OF T~ SCION
The present invention provides a single-step process which is understood to be
a
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process that could be accomplished in a single reactor and which does not
require any
changes in reaction conditions during the process. However, it is understood
that in
certain polymerisation processes it might be advantageous to transfer the
reactor content
in another reactor with the same or a different set of reaction conditions.
Those set-ups
S arc deemed to be within the present teaching.
The present invention is not limited to a certain type of isoolefins. However,
isoolefins which are preferably used ans those of formula
CHI--CR6R~
where R6 = Me and R' represents a C'-Cs alkyl such as methyl, ethyl or propyl.
Lcobutene
and 2-meehylbutene-1 arc particularly preferred, especially isobutene.
The present invention is not limited to a certain type of ally! halides.
However,
preferred are allyl halides of the general formula (I)
R'RZG-CR3CXR4R5 (I),
in which X denotes for a halide, preferably chloride, and R'-RS are selected
independently
of each other and each R denotes for hydrogen, a C~-C2o alkyl, a Cs-CZO aryl,
a C~-Go
a>kylaryl or a C~-Ceo arylatkyl. the following radicals are particularly
suitable as C'-Czo
alkyl radicals: methyl, ethyl, propyl, butyl, hexyl, octyl, deeyl and eicosyl,
preferably
methyl, ethyl and propyl, most preferably methyl. Each R may contain
hcceroatoms in the
chain at long as those heterostoms will not prohibit the polymorieation. Allyl
chloride
(HzC=CH-CHiCI), 3-chloro-2-methyl-1-propene (methallyl chloride), 1-chloro-2-
butene
(crotyl chloride) are particularly preferred.
Suitable co-monomers for the present invention are all co-polymerizable
monomers lntown to the skilled in the art. Preferred co-monomers are
conjugated or non-
conjugated dienes and styrene derivatives, such as alkyl styrenes and divinyl
benzenes.
Conjugated or non-conjugated dienes which ane suitable for the process
according
to the invention are those which contain 4 to 20, preferably 4 to 10, most
preferably 4 to 6
carbon atoms, such as butadiene, isoprene, piperylene, 2,3-dimethylbutadiene,
2,4
dimethylpentadiene-1,3, cyelopentadiene, methylcyclopentadiene, limonene,
'myrcene
andlor 1,3-cyclohcxadicnc, prcfcrably isoprene, piperylene and/or
dlmethylbutadlene,
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CA 02388739 2002-06-03
most preferably isoprene.
The production of butyl rubber, i.e. the copolymerisation of ally! halides,
isobutene and isoprene, is quite particularly preferred.
If co-monomers are present, the molar ratio of ally! halides) to the co-
monomers
used is usually within the range of from 1:104 to 1:10, preferably 1:10'' to
1:50, most
preferably 1:10 to 1:24.
When copolymcrizing with isoolefins and dienes, the molar ratio of isoolefins
to
dienes is usually 1:103 to 1:10, preferably l:IOZ to 1:50.
The process according to the invention can be advantagcouely conducted in the
presence of one or more inert organic culvants such as linear or branchod
hydnxorbons
andJor linear and branched halogenated hydrocarbons, such ar, pentane, hexane
and/or
methylene chloride. In this rospect, the amount of inert solvent used is not
critical. The
most suitable amount can easily be determined by appropriate preliminary
tests.
As initiators alkylalumoxanes may be used. Suitable, preferred alkylalumoxanes
are methyl, ethyl and/or butylalumoxanes, particularly methylalumoxanes, such
as those
described in Polyhedron, Vol. 7, No. 22123 (1988), page 2375 et seq. Other
suitable
initiators are compounds of the general formula R"AlX3.e, with each R being
independently a CrC4o group and each X being independently a halogen, such as
ethylaluminum dichloride. Of course, ii is possible to use a mixture of
different
initiators to custom tailor the initiation profile. Alkylaiumoxanes and
mixtures of
alkylalumoxanes with said compounds of the general formula R"AIX~.", with each
R
being independently a Ct-Cso group and each X being independently a halogen
arc
preferred in this respect. In the procxss according to the invention, tha
initiators) and the
ally! halides are usually used in a molar ratio from 1:104 to 1:10, preferably
from 1:103 to
1:3, most preferably from !:!0i to 1:2.
Other suitable additives can also be added for the polymerisation according to
the
invention. Examples of suitable additives include electron donors such as
dimethyl-
acetamide and/or dimethyl sulphoxide, or proton acceptors such as di-tert:
butylpyridine
(see US 5169 914, for example).
It is important to note that the process of the present invention does not
require the
presence of metal salts such as Ti- or Sn-salts. This feawre tenders is
extremely suitable
for solution polymerizations.
The initiator can be addod to the monomer mixturt to be polymerised
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CA 02388739 2002-06-03
simultaneously, in succession, continuously or batch-wise. The alkylalumoxanes
can of
course be produced in situ in the lrnown manner, by the hydrolysis of
corresponding
aluminum alkyls.
The grocess according to the invention usually will be conducted within the
S temperature range from +20 to -100°C, preferably within the
temperature range from -20
to -90°C, particularly from -40 to -80°C.
The process according to the invention can be conducted in solution,
suspension
or in the gas phase. It is preferably conducted in solution in a inert
hydrocarbon solvent,
such ~ hexane. It is also possible to conduct the process 8s n batch, flow or
continuous
process, where the reaction times or residence times range from 2 seconds to
20 hours,
preferably from 60 seconds to 1 hour. particularly from IS to 40 minutes.
As mentioned above, the process according to the invention results in
polymers,
wherein the degree of branching and the molecular weight are dependent in
particular on
the reactivity of the allyl halide, on the initiator, on the concentration of
the initiator, on
the molar ratio of monomer to allyl halide, on the reaction temperature and on
the reaction
time. It is therefore possible individually to adjust the degree of branching
and the
molecular weight of the resulting polymer to be produced, by suitably varying
the
sfommentioned parameters.
For example, ttte process according to the invention can be conducted in a
manner
such that the reactor, which is cooled to the reaction temperature, is charged
with purified
solvent and with the monomers, and after adjusting the temperature of the
reactor to the
decirod reaction temperature the requisite amount of initiator is added end is
slimed with
the monomer mixture placed therein. The reactor contents are vigorously and
thoroughly
mixed. All manipulations favourably are carried out under an inert gas. The
course of the
polymerisation could be followed by monitoring the generation of heat. After
the
completion of the exothermic reaction, the polymerisation usually is
terminated, e.g. with
2,S-di-tart: butyl-4-methoxypheno! dissolved in ethanol. The polymer obtained
usually is
then worked up in the usual manner, e.g., by coagulation or steam stripping.
The advantages of the process according to the invention are due in particular
to
the simple single-step reaction procedure, wherein defined, branched co-
polymers,
preferably butyl rubbers, are obtained, which exhibit superior processing
properties.
The invention is further illustrated in the following Examples.
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CA 02388739 2002-06-03
EXAMPLES
The polymers were investigated by the gel permeation chromatography with a
triple detector for determination of absolute molecular weights. The testing
was done
using Viscotek, TDA model 300, with Waters Alliance 2690 Separation Module
equipped with one GPC linear column. Tetrahydrofuran served as the eluent with
the
flow race 0.5 mLmin. The composition of polymers was determined by'H 1V1VIR
500
MHz spectroscopy (Bruker Avance DRX-S00) with TMS as an internal standard for
0
ppm. Tha samples were diasolvcd in deutcratcd chloroform (Aldrich).
Calculations
were based on integrated aliphatic, olafinic and inimor pocks.
The n-hexane (Philips 66 Co.) was dried and distilled over CaHz before its ure
as a reaction medium for polymerizations.
Methylalumoxane (1v1A0, Aldrich) was used as ready-made 10 wt. °!o
solution
in toluene.
1S
EXAMPLE 1
2S0 mL of dry hexane were placed in a S00 rnL round bottom flask equipped
with an overhead stirrer, cooled to - 80 °C, mixed with 106.4 mL of
isobutene at
- 80 °C followed by adding 3.13 mL of isoprene measured at room
temperature. The
reaction mixture was cooled down to - 80 °C and 200 I,tL, of
ethylaluminum dichlori~
(1.0 M solution in hexanes) was added to start the reaction.
Tha reaction was carried out in MHRAUN~ dry box under the atmosphere of
dry nitrogen. The reaction was terminated after 24 minutes by adding 5 mL of
ethanol
NaOH solution into the reactor.
2S The gravimetrically determined yield was 24.3 g. Characterization of the
polymer by GPC-Viscotek gave Me = 117,400, MW = 210,100, and Mi = 360,800.
Isoprene content was 1.81 mole percent.
This example is provided for comparative purposes for Example 2 and Example
3.
EXAMPLE 2
The reaction feed was prepared similarly like in Example 1, but in this case
2.52
mL of mcthallyl chloride was also added to the feed (measured at room
temperature).
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The reaction mixture was cooled down to - 80 °C and 200 ~tl, of
ethylaluminum
dichloride (1.0 M solution in hexanes) was added to start the reaction.
The reaction was carried out in MBRAUIVQ° dry box under the
atmosphere of
dry nitrogen. The reaction was terminated after 24 minutes by adding 5 mL of
ethanol
NaOH solution into the reactor.
The gravimetrically determined yield was 25.8 g. Characterization of the
polymer by GPC-~scotek gave Mn = 99,740, MW = 178,900, and MZ = 320,600.
Isoprene content was 1.85 mol percent and methallyl chloride content was 1.03
mol
percent.
~:1~ 3
The reaction feed was prepared exactly like in Example 2.
The reaction mixture was cooled down to - 80 °C. 2.0 mL of 10 wt
°~6 solution
of methylalumoxane (MAO) in toluene and 400 LtL, of ethylaluminum dichloride
(1.0 M
solution in hexanes) was mixed together. The reaction was initiated with 1.80
mL of
the above solution.
The reaction was carried out in MHRAIJN~ dry box under the atmosphere of
dry nitrogen. The reaction was terminated after 60 minutes by adding 5 mL of
ethanol
NaOH solution into the reactor.
The gravimetrically determined yield was 35.5 g. Characterization of the
polymer by GPC-Viscotek gave Mo = 128,400, Mw = 297,500, and MZ = 747,600.
Isoprene content waa 2.34 mot percent and no allylic chloride was detectable.
The
increase of Mt indicates the branched structure of the polymer.
EXAMPLE 4
500 mL of dry hexane were placed in a 2 L reactor equipped with an overhead
stirrer, cooled to - 80 °C, mixed with 212.75 mL of isobutene at - 80
°C followed by
adding 6.~6 mL of isoprene measured at room temperature. The reaction mixture
was
cooled down to - 80 °C and 450 IrL, of ethylaluminum dichloride (1.0 M
solution in
hexanes) was added to start tho roaction.
The reaction was carried out in MBRAUN'a dry box under the atmosphere of
dry nitrogen. The reaction was terminated after 60 minutes by adding 5 mL of
ethanol
8
CA 02388739 2002-06-03
NaOH solution into the reactor.
The gavimetrically determined yield was 78.? g. Characterization of the
polymer by GPC-Yacotek gave M" = 87,330, MW = 162,900, and MZ = 286,800.
Isoprene content was 1.87 mol percent.
This example is provided for comparative purposes for Example 5.
EXAMPLE 5
The reaction feed was prepared similarly like in Example 4, but in this case
5.04
mL of mathallyl chloride was also added to the feed (measured at room
temperature).
The reaction mixture wao cooled down to - 80 °C and 5.0 mL of 10
wt. ~b
solution of MAO in toluene was added to start the reaction. The reaction was
carried
out in MHRACJIV~ dry box under the atmosphere of dry nitrogen. The reaction
was
terminated after 2 hours by adding 5 mI, of ethanol NaOH solution into the
reactor.
The gcavimetrically determined yield was 84.5 g. Characterization of the
1 S polymer by GPC-Viscocek gave M, = 69,570, Mw = 153,600, and M= = 335,200.
Isoprene content was 2.48 mol percent and methallyl chloride content was 0.22
mol
percent.
The Mark-Houwink plots for polymers obtained in Example 4 and Example 5
were compared. The plot for Lhe polymer containing methallyl chloride deviated
from
the line for polymer obtained in reaction 4 (in the high end of molecular
weights)
indicating ehet the polymer with mcthallyl chloride had a branched structure.
9
