|Title of Invention||
OLEFIN POLYMERISATION PROCESS IN THE PRESENCE OF AN ANTI-FOULING AGENT
|Abstract||The invention discloses a propylene polymerisation process carried out in the presence of an anti-fouling agent; characterised in that the anti-fouling agent comprises an anti-fouling polymer containing: (1)one or more blocks -(CH2-CH2-O)k- where each k is in the range from 1 to 50; and (2)one or more blocks -(CH2-CH(R)- O)n- where R comprises an alkyl group having from 1 to 6 carbon atoms and each n is in the range from 1 to 50; and terminated by a R' and a R" end groups wherein R' is OH or an alkoxy having from 1 to 6 carbon atoms and R" is H or an alkyl having from 1 to 6 carbon atoms; and the anti-fouling polymer is solvated in a solvent comprising cyclohexane when added to the polymerisation medium.|
|Full Text||The present invention concerns a new olefin polymerisation process for preventing
fouling in the polymerisation reactor. The invention concerns propylene
polymerisation processes using a metallocene-type catalyst, or Ziegler Natta-type
Olefin polymerisation processes are well known. Among the processes, slurry
polymerisation in suspension in a solvent or in the liquid monomer is extensively
practiced. Such processes are performed in a stirred tank reactor, or in closed loop
reactors. One or more reactors can be used. In such processes, solid polymer
particles are grown on small catalyst particles. Released heat of polymerisation is
eliminated through cooling through the reactor's walls and/or a heat exchanger.
However, it has been found on an industrial scale that while the polymer particles are
insoluble or substantially insoluble in the diluent, the polymer product has some
tendency to deposit on the walls of the poly merisation reactor. This so -called
"fouling" leads to a decrease in the efficiency of heat exchange between the reactor
bulk and the coolant around the reactor. This leads in some cases to loss of reactor
control due to overheating, or to reactor or down stream polymer processing
equipment failure due to formation of agglomerates (ropes, chunks).
This "fouling" is caused in part by fines and also by the build up of electrostatic
charge on the walls on the reactor. Attempts to avoid fouling during slurry
polymerisation have been made by adding an antifouling agent in the polymerisation
medium. Typically, the antifouling agent acts for example to make the medium more
conductive, thus preventing to some extent the formation of electrostatic charge,
which is one cause of the build -up of polymer on the wall of the reactor.
US 3,995,097 discloses a process whereby an olefin is polymerised in a hydrocarbon
diluent using a catalyst comprising chromium oxide associated with at least one of
silica, alumina, zirconia, or thoria. Fouling of the reactor is said to be reduced by
adding a composition, which comprises a mixture of aluminium or chromium salts of
an alkyl salicylic acid and an alkaline metal alkyl sulfosuccinate. It is said that it is
desirable to dissolve the anti-fouling composition in a hydrocarbon solvent, such as
n-decane. Further, it is said that paraffins of 9 to 20 carbon atoms are the preferred
solvents, although naphthenic solvents also are mentioned.
EP 0,005,215 is concerned with a process fo r polymerising olefins in a hydrocarbon
diluent again using a catalyst comprising calcined chromium compound associated
with at least one of silica, alumina, zirconia or thoria or using a catalyst system such
as those disclosed in US 2,908,671, 3,919,185 a nd 3,888,835. The process uses an
anti-fouling agent comprising a compound containing a sulphonic acid residue. The
anti-fouling agent is a composition comprising (a) a polysulphone copolymer (b) a
polymeric polyamine, and (c) an oil soluble sulphonic ac id. It is mentioned that the
solvent for the anti-fouling additive can be the same material used as the diluent in
the polymerisation reaction or it can be different, so long as it does not interfere with
the polymerisation reaction. In the Example, the ad ditive product known as STADIS
450 (in toluene) is used as the anti fouling agent.
US 6,022,935 (equivalent to EP 0,803,514) discloses a process for the preparation of
polymers of C2-C12 alk-1-ene using a catalyst system containing a metallocene
complex. An antistatic agent is used in the process. It is said that in general, all
antistatic agents which are suitable for polymerisation may be used. Examples given
are salt mixtures comprising calcium salts of medialanic acid and chromium salts of
N-stearylanthranilic acid, C12-C22 fatty acid soaps of sulfonic esters of the general
formula (RR')-CHOSO3Me, esters of polyethylene glycols with fatty acids, and
polyoxyethylene alkyl ethers. STADIS 450 also is mentioned. The antistatic agent is
preferably used in solution.
EP 0,820,474 is concerned with preventing sheeting problems in gas phase reactors
in polymerisation processes, which comprise at least one loop reactor followed by at
least one gas phase reactor. These problems are addressed using a fouling
preventive agent that is a mixture of Cr salt of C14-C18 alkyl-salicylic acid, a Ca dialkyl
sulphosuccinate and a copolymer of alkylmethacrylate with 2 -methyl-5-vinylpyridine
in solution in xylene. Chromium-type catalysts, Ziegler-type catalysts and
metallocene catalysts are mentioned. In the examples, the fouling prevention agent
used is the commercial product TOLAD 511 in propane or ASA 3 (in xylene).
JP 2000-327,707 discloses a slurry olefin polymerisation method. The method
addresses the problem of fou ling and sheeting of the reactor wall, which is observed
particularly when the catalyst is a supported metallocene catalyst. The method is said
to be carried out in the presence of one compound chosen from polyalkylene oxide
alkyl ether, alkyl diethanolami ne, polyoxyalkylene alkyl amine, and polyalkylene oxide
block. The chosen compound is used in the liquid form.
The anti-fouling agents disclosed in JP 2000-327,707 generally may be considered
as polymeric viscous products. Their viscosity (in the region o f a Brookfield viscosity
of about 1200cps) makes the anti -fouling agent difficult to pump.
It is possible to reduce viscosity by heating the agent and work has been done in the
past to pump heated anti -fouling agent to solve this problem. However, the pr esent
inventors have found that this in fact is technically complicated and causes some
EP 1,316,566 discloses propylene polymerisation in a bulk loop reactor. The
disclosure is concerned specifically with the transition from one catal yst type to
another in a bulk loop reactor and with problems associated therewith. The process
involves injecting a metallocene catalyst and a Ziegler -Natta catalyst into the bulk
loop reactor. It is mentioned on page 3 paragraph  that in one embod iment, a
of a stream of propylene with a stream of catalyst. The antifouiing agent is used in
liquid form. According to the disclosure of EP 1,316,566 any antifouiing ag ent would
not at any stage be solvated in a solvent comprising cyclohexane.
In view of the above, it will be seen that many so called anti -fouling agents for use in
various olefin polymerisation processes are known. However, there have been some
problems associated with prior known agents. An increase of catalyst consumption
due to loss of activity in the presence of the anti -fouling agent is observed, even at
the low levels typically used in the polymerisation process. Catalyst activity loss is
linked to the poisoning of active sites, for example by the polar moieties of the anti -
fouling agent (alcohol and sulphonate ...). Other problems with prior known agents
relate to problems of toxity. This is a particular concern with Cr -based anti-fouling
agent or with agents such as commercial Stadis 450 as described in EP 0,005,215,
because of its toluene (as solvent) and active ingredient content.
Also, practical problems are encountered with many previously known anti -fouling
agents. These practical problems a rise because some antifouiing agents are usable
only with a given catalyst type. This makes transitions between catalyst systems
during processing more difficult.
A further problem arises for a propylene polymerisation process. This is because it is
not desirable for the propylene monomer to be used as a suspension medium for the
anti-fouling agent, because, in these circumstances, the viscosity means that the
liquid is too difficult to pump. The viscosity is important because this affects the ease
of pumping the liquid. Further, the concentration of the pumped liquid affects the
accuracy of pumping and also problems relating to pressure. With regard to the
accuracy of pumping, it will be understood that a degree of error of, for example, plus
or minus 0.5 on a solution of concentration that is pumped at a rate of 1 litre per hour
has more effect than on a solution that is pumped at a rate of 5 litres per hour, where
In this sense, there remains a particular need to provide new anti -fouling agents for
use in propylene polymerisation processes where it is not desirable for the propylene
monomer to be used as a suspension medium for the anti -fouling agent.
The present inventors have identified that a solvated anti -fouling agent may solve this
There is however a technical prejudice against using a solvent since the introduction
of a further material into the polymerisation medium can affect the reaction and the
end product and generally is to be avoided.
To this end, the present inventors identified and took into consideration several
desirable so-called results to be achieved when trying to provide a solvated anti
fouling agent. Firstly, a "light" solvent was needed, that was easy to remove from the
polymer product. Secondly, the solvent had to be free of toluene or aromatics for
safety reasons. Thirdly, the solvent had to sufficiently dissolve the antifouling agent.
The antifouling agent is generally viscous and needs t o be dissolved in order to
improve the spraying accuracy. Finally, there had to be ease of separation of the
monomer and the polymer product from the solvent.
This problem now has been solved at least partially by the provision of a propylene
polymerisation process carried out in the presence of an anti -fouling agent;
characterised in that the anti-fouling agent comprises an anti-fouling polymer
(1) one or more blocks -(CH2-CH2-O)k- where each k is in the range from 1 to
(2) one or more blocks -(CH2-CH(R)-O)n- where R comprises an alkyl group
having from 1 to 6 carbon atoms and each n is in the range from 1 to 50;
and terminated by R' and R" end groups, wherein R' is OH or an alkoxy having from
and the antifouling polymer is solvated in a solvent comprising cyclohexane when
added to the polymerisation medium.
In the present process, (CH2CH(R)O)n blocks generally may be considered to be
lipophilic whereas (CH2CH2O)k blocks may be considered to be hydrophilic.
Preferably, one end of the polymer is hydrophilic and the other end or the middle of
the polymer is lipophilic.
Such a polymer as contained in the present anti -fouling agent is known per se,
particularly outside the field of olefin polymerisation. In this regard, such a polymer is
known as a lubricant or washing detergent.
However, it has been surprisingly found by the present inventors that such a polymer
may be used advantageously in a propylene polymerisation m ethod when in a
solvent comprising cyclohexane. The very good solubility of such a polymer as
described above in cyclohexane was unexpected. In one embodiment, a "perfect"
solubility of polymer in cyclohexane at room temperature was determined. In addition
the selection of cyclohexane also fulfils the low toxicity and the easy removal
The diluted polymer has reduced viscosity. This makes it easier to pump, especially
in the small quantities generally used in the method. Further, it will be a ppreciated
that cyclohexane avoids the safety problems that are associated with some other
solvents such as toluene and aromatics, which hitherto have been widely used as
solvents for anti-fouling agents.
Furthermore, it has been found that improved acti vity or at least no loss of activity
occurs in the present process as compared with an equivalent process which uses
Stadis 450 in toluene as the anti -fouling agent. This means that the present method
suitably can be used in an olefin polymerisation proces s carried out in the presence
catalyst or a Ziegler-Natta type catalyst. This is particularly advantageous since, for
logistical reasons, it is preferable to be able to use a s ingle anti-fouling agent in olefin
polymerisation processes regardless of the type of catalyst. This is however not
possible with most previously known anti -fouling agents without loss of activity with
one of the catalyst types.
Preferably, the polymer in the present anti-fouling agent is diluted to a concentration
of from 10 to 20 wt%. The optimum concentration can be obtained by balancing the
advantages of a lower viscosity and a less concentrated liquid against the
disadvantages associated with the intr oduction of a large volume of a solvent.
It will be understood in the present process that, where necessary, an activating
agent will be needed to activate the catalyst or to modify the product polymer
properties. Suitable activating agents, where neede d, are well known in this art.
Suitable activating agents include organometallic or hydride compounds of Group I to
III, for example those of general formula AIR 3 such as Et3AI, Et2AICI, and (i-Bu)3AI.
One preferred activating agent is triisobutylaluminium .
Where the polymerisation process is a slurry polymerisation process, typically, the
polymerisation process will be carried out in suspension in the bulk liquid propylene
monomer. A separate catalyst diluent may be required.
The anti-fouling agent may be added at any suitable stage in the process. The
addition can be carried out continuously or batch wise. The solvated anti -fouling
polymer may be added to the polymerisation medium separately or may be mixed
with the propylene monomer and then added to the polymerisation medium.
Advantageously, the solvated anti-fouling agent may be added via the monomer
header in order to introduce the agent evenly in the reactor.
The anti-fouling agent desirably is liquid at room temperature and , as such, the anti -
determine whether the anti -fouling polymer is liquid at room temperature. These are:
the molecular weight of the anti -fouling polymer and the wt% ethylene oxide in the
Preferably, the wt% ethylene oxide in the anti -fouling polymer is in the range of from
5 to 40 wt%, more preferably from 8 to 30 wt%, even more preferably from 10 to 20
wt%, most preferably about 10 wt%.
Further, the anti-fouling polymer preferably has a molecular weight (MW), not higher
than 5000. In order to avoid any poisoning effect on the catalyst and to minimise
elution of residues from the formed polymer product, the molecular weight is greater
than 1000 Daltons, preferably greater than 2000 Daltons, more preferably in the
range from 2000-4500 Daltons.
It will be understood from the above that in order to ensure that the anti -fouling
polymer is liquid at room temperature, one must balance the molecular weight of the
anti-fouling polymer and the wt% ethylene oxide in the anti -fouling polymer. It is to
be noted that the activity of the anti -fouling polymer decreases as the molecular
weight increases. Therefore, in practice, it may be desirable to increase the wt%
ethylene oxide in the anti-fouling polymer in order to ensure that the solvated anti •
fouling agent is liquid at room temperature, rather than increase the molecular weight
of the anti-fouling polymer.
It will be appreciated from the above that the molecular weight of t he anti-fouling
polymer should be selected in combination with the wt% ethylene oxide content in
the anti-fouling polymer. For guidance value, the present inventors have found that
an anti-fouling polymer having an ethylene oxide content of 10 wt% and a m olecular
weight in the range of from 4000 to 4500 is particularly useful in the present process.
Cyclohexane has a high freezing point (6.5 °C) and a solution of the present anti -
weather it is desirable in the present process to use a mixture of solvents in the anti -
fouling agent. Where a mixture of solvents is used, the mixture of solvents comprises
cyclohexane and another solvent which serves to lower the freezing point of the anti-
Preferably, the another solvent lowers the freezing point without substantially
reducing the solubility of the anti -fouling agent in the solvent. To this end, preferably,
the other solvent is selected from the group consisting o f linear hexane, branched
hexane, linear pentane, branched pentane, cyclopentane, and mixtures thereof.
More preferably, the other solvent is selected from the group consisting of branched
hexane and branched pentane. Branched hexane and branched pentane are
preferred for safety reasons. Isohexane is particularly preferred. As such, the
mixture of solvents preferably comprises cyclohexane and isohexane. This
advantageously serves to lower the freezing point of the anti -fouling agent in solution,
without reducing solubility.
Preferably, the mixture of solvents contains cyclohexane and up to about 15 wt% of
the another solvent, preferably from 8 to 15 wt%, most preferably about 10 wt%.
Generally, the anti-fouling polymer is used at the lowest possible concentration
effective to prevent or substantially reduce fouling. This can be determined by routine
experimentation. Preferably it is used at a concentration of from 0.5 to 20 ppmw in
the polymerisation medium, more preferably from 2 to 10 ppmw.
Preferably, the anti-fouling polymer is a block polymer, more preferably a triblock
Preferably, the anti-fouling polymer is a block polymer of general formula:
R'-(CH2-CH2-O)k-(CH2-CH(R)-O)n -(CH2-CH2-O)m-R" (I)
where R comprises an alkyl group; R' and R" are end groups; k is from 1 to 50; n is
from 1 to 50; m is greater than or equal to 1; a is from 1 to 50; b is from 1 to 50; and c
is from 0 to 50. k and m may be the same or different.
Preferably R is a C1 to C3 alkyl group. More preferably, R is a methyl group.
Preferably, in one embodiment, k is greater than 1 and m is greater than 1. Also
preferably, in another embodiment a is 0 or c is 0.
Preferred R' and R" groups include H; OH; alkyl, and alkoxy groups. Preferred alkyl
groups are C1 to C3 alkyl groups. Preferred alkoxy groups are C1 to C3 alkoxy
groups. In this regard, as mentioned above, the ends of the polymer should be
hydrophilic. Therefore, in formulae (I) and (II) above , it is preferred that R' is OH or
an alkoxy group, preferably OH or a C1 to C3 alkoxy group. Further, it is preferred
that R" is H or an alkyl group, preferably H or a C1 to C3 alkyl group.
A particularly preferred anti -fouling polymer has general formu la (III):
R'-(CH2-CH2-O)k-(CH2-CH(CH3)-O)n -(CH2-CH2-O)m-R" (III)
where R', R", k, n, and m independently are as defined anywhere above in relation to
formulae I and II.
A further preferred anti -fouling polymer has general formula (IV):
OH-(CH2-CH2-O)k-(CH2-CH(R)-O)n -(CH2-CH2-O)m-H (IV)
where R, k, n, and m independently are as defined anywhere above.
It will be appreciated that, by virtue of the preferred molecular weights for the present
anti-fouling polymer and the preferred ethylene oxide co ntents in the present anti -
fouling polymer given above, preferred values for a, b, c, k, n, and m can be derived.
The present process may be used to make a propylene homopolymer or copolymer
or higher order polymer. Where the present process is used to m ake a propylene
copolymer or higher order polymer, preferred comonomers include ethylene and
butylene. The copolymer or higher order polymer may be in a random, alternating, or
block configuration. Preferred copolymers include a propylene -ethylene copolymer
and a propylene-butylene copolymer. A preferred terpolymer is a propylene -
Where the copolymer or higher order polymer is in a block configuration, one way of
making the polymer is to make the homopolymer "blocks" and, su bsequently, to
introduce these pre-made "blocks" into the polymerisation medium with a
comonomer. Alternatively, the "block" polymer can be made in a polymerisation
medium containing the propylene monomer with a small quantity of the comonomer.
A preferred reaction temperature range may be said to be from 40°C to 110°C, more
preferably from 50 to 90 °C, most preferably from 60 to 80°C.
A preferred applied pressure range may be said to be from 5 to 200 barg, more
preferably from 30 to 70 barg depending on the reactor configuration and on the
Generally, Ziegler-Natta type catalysts usable in the present process comprise a
transition metal compound of Group IV -VIII (mainly Mg, Ti or V) supported or not on a
carrier. Such catalysts are well known i n the art. Examples of Ziegler-Natta catalysts
are TiCl4, TiCl3, VCl4, VOCl3. Titanium chloride supported on a chlorinated Mg
Late transition metal catalysts usable in the present process include ni ckel
complexes and iron complexes such as disclosed for example in Ittel et al. (S.T. Ittel,
L.K. Johnson and M. Brookhaert, in Chem. Rev., 2000,1169.) and in Gibson and
Spitzmesser (V.C. Gibson and S.K. Spitzmesser, in Chem. Rev., 2003,283.).
Catalysts of this type will be well known to a person skilled in this art. _
Generally, metallocene-type catalysts usable in the present process comprise an
organometallic complex. A preferred metallocene -type catalyst is a complex of an
organometallic compound and M AO.
In the present process, it is generally preferred that the process is carried out in the
presence of a metallocene-type catalyst. It is further preferred that the metallocene -
type catalyst is activated by tri isobutyl aluminium as the activating agent . It is also
preferred that the metallocene-type catalyst is supported, desirably on a silica
Particularly preferred metallocene -type catalysts will be governed by the desired end
product. In this regard, the skilled person will know certain pre ferred metallocene-
type catalysts for preparing a syndiotactic polypropylene. For example, a
metallocene-type catalyst having a general formula (1) is preferred for making a
wherein Cp is a cyclopentadienyl group; Cp' is a fluorenyl group; R" is a structural
bridge imparting stereorigidity to the catalyst; M is a metal atom from Group IV(b),
V(b) or Vl(b); and each Q is a hydrocarbyl group having from 1 to 20 carbon atoms or
a halogen and p is the valance of M minus 2. Cp and Cp ' may be substituted with the
restriction that the substituents are selected to preserve Cs symmetry of the catalyst
Further, the skilled person would know the preferred number of substituents and the
preferred positioning of any substituent.
The skilled person also will know suitable catalysts for making an isotactic
polypropylene. For example, a catalyst of the general formula (2) is preferred for
making an isotactic propylene:
(lndH4)2R' MQz (2)
wherein each Ind is the same or different and is substituted or unsubstituted indenyl
or tetrahydroindenyl; R" is a bridge which imparts stereorigidity to the catalyst; M is a
Group IV metal or vanadium; and each Q independently is a hydroc arbyl having 1 to
20 carbon atoms or halogen; Z is the valancy of M minus 2, and the substituents on
the indenyls or tetrahydroindenyls, if present, are selected to impart C1 or C2
symmetry to the catalyst component.
One bulk reactor type which may be app lied in slurry polymerisation processes is a
turbulent flow reactor such as a continuous pipe reactor in the form of a loop. A
continuous pipe reactor in the form of a loop is operated in liquid full mode, using
liquid propylene as the liquid medium. Such a so-called loop reactor is well known
and is described in the Encyclopaedia of Chemical Technology, 3 rt Edition, Vol. 16
page 390. This can produce LLDPE and HDPE resins in the same type of
A loop reactor may be connected to one or more furt her reactors, such as another
loop reactor. A loop reactor that is connected to another loop reactor may be referred
to as a "double loop" reactor.
Other types of bulk reactors such as stirred tank reactors may be used instead of a
loop reactor, again u sing the bulk monomer as the liquid medium. A stirred tank
reactor also may be used in combination with a loop reactor, where a first reactor that
is a loop reactor is connected to a second reactor that is a stirred tank reactor.
In some cases it may be advantageous for a gas phase reactor also to be
incorporated. The gas phase reactor may be a second reactor that is connected to a
first reactor such as a loop reactor or a stirred tank reactor. Alternatively, a gas
phase reactor may be connected as a t hird reactor in the apparatus. In the gas phase
reactor (if present), the elastomeric part of a copolymer or higher order polmer
product may be produced. The elastomeric part of the polymer product gives impact
properties to the product. The elastomeric pa rt of the polymer product typically is
The bulk reactor(s) may be connected to a gas phase reactor, for example where it is
desirable to prepare a "block" polymer. For example, a "block" propylene -ethylene
copolymer may be made by first polymerising propylene monomers in the bulk
reactor. Optionally, there may be a small quantity of ethylene comonomers present.
The present invention now will be described in further detail with reference to the
attached drawings in which:
Figure 1 shows a general scheme for the introduction of the antifouling agent into the
polypropylene polymerisation reactor. Pumping is done with a metering pump.
Figure 2 shows a double loop reactor that is useable in the process according to the
Figure 3 represents the viscosity of synperonic experessed in cps as a function of
temperature expressed in °C.
The following embodiment describes apparatus that is useable in the present
In the first reactor, the liquid propylene monomer polymerises in the presence of
hydrogen, catalyst, activating agent, anti -fouling agent and optionally a comonomer.
- The first reactor essentially consists of four or more vertical jac keted pipe sections
(1a, 1b, 1c, 1d, 1e, 1f) connected by trough elbows (3a, 3b, 3c, 3d, 3e, 3f) as shown
for example in Figure 2 where there are six vertical jacketed pipe sections. There are
three lower trough elbows in the reactor in Figure 2 (3b, 3d, 3f) and three upper
trough elbows (3a, 3c, 3e). The slurry is maintained in circulation in the reactor by an
axial pump (2). The polymerisation heat may be extracted by water cooling jackets
around the vertical pipe sections (legs). The reactants, diluen t and antifouling agent
conveniently are introduced into one of the lower trough elbows of the first reactor,
close to the circulating pump. For example, in Figure 2, this could be in the position
- The polypropylene product may be taken out of one or more of the lower trough
elbows of the reactor, with some diluent. Typically, the product is removed from a
different trough elbow to the trough elbow into which the reactants, diluent and
antifouling agent are introduced. For example, in Figure 2, when the reactants,
diluent and antifouling agent are introduced at position "4", the product could be
removed from trough elbow 3b or 3d.
The product from the first reactor then may be transferred to the second reactor. If
the second reactor also is a loop reactor, the product from reactor 1, optionally further
anti-fouling agent and further reactants conveniently are introduced into one of the
lower trough elbows of the second reactor, close to the circulating pump. If a
copolymer product is desi red, a homopolymer reaction may be carried out in the first
reactor and a copolymer reaction carried our in the second reactor. Suitable
apparatus for such a process is shown in Figure 20 on page 508 of the
Encyclopaedia of Polymer Science and Engineering , Vol. 13,1988.
In some embodiments it will be advantageous for the second reactor to be a gas
phase reactor. Alternatively, where the second reactor is not a gas phase reactor, it
may be advantageous for the apparatus to comprise a third reactor that i s connected
to the second reactor that is a gas phase reactor.
If the process is carried out using two reactors in series, the product of the first loop
reactor collected through the slurry removal system is re -injected in the second
reactor with additional diluent and monomer. If required, additional antifouling agent
can also be added to the second reactor. A concentration of the slurry between the
reactors can sometimes be performed, e.g. through the use of hydro -cyclone
A continuous discharge system can be used.
Alternatively, slurry removal conveniently may be performed through settling legs and
discontinuous discharge valves or slurry removal can be performed using a wash
column or centrifuge apparatus.
Where slurry removal is perfor med through settling legs and discontinuous discharge
valves, a small fraction of the total circulating flow is withdrawn.
After removal of the slurry from the reactor, the product is recovered. The product
can be recovered using a variety of techniques including using a wash column.
Alternatively, it may be moved to a polymer degassing section in which the solid
content is increased. While being depressurised, the slurry may be degassed, e.g.
during transfer through heated flash lines to a flash tank. In the flash tank, the
product and diluent are separated. The degassing can be completed in a purge
The powder product is then further additivated and processed into pellets or
The polymerisation of polypropylen e was carried but in a double loop reactor with a
metallocene-base catalyst system. The synperonic has a very high viscosity that
decreases with increasing temperature as can be seen in Figure 3 that represents
the synperonic viscosity expressed in cps as a function of temperature expressed in
°C. It was thus added as a solution of 19 wt% in cyclohexane in order to reduce the
viscosity thereby enabling the solution to be pumped at room temperature (in the
winter, it may be necessary to add a quantity of he xane of up to 10 % in order to
prevent the solution from freezing). The antifouling agent was added at a throughput
that resulted in a concentration of 5 ppm in the reactor. The results are summarised
in Table 1.
1. A propylene polymerisation process carried out in the presence of an anti-fouling
agent; characterised in that the anti-fouling agent comprises an anti-fouling polymer
(1)one or more blocks -(CH2-CH2-O)k- where each k is in the range from 1 to 50;
(2)one or more blocks -(CH2-CH(R)-O)n- where R comprises an alkyl group
having from 1 to 6 carbon atoms and each n is in the range from 1 to 50;
and terminated by a R' and a R" end groups wherein R' is OH or an alkoxy having
from 1 to 6 carbon atoms and R" is H or an alkyl having from 1 to 6 carbon atoms;
and the anti-fouling polymer is solvated in a solvent comprising cyclohexane when
added to the polymerisation medium.
2. A process as claimed in claim 1 wherein R is methyl.
3. A process as claimed in claim 1 or claim 2, wherein the anti-fouling polymer is
present at a concentration of from 10 to 20wt.% in the solvent.
4. A process as claimed in any one of claims 1 to 3, wherein the anti-fouling polymer
is liquid at room temperature.
5. A process as claimed in any one of claims 1 to 4, wherein the solvent optionally
comprises a further solvent selected from the group consisting of linear hexane,
branched hexane, linear pentane, branched pentane, cyclopentane, and mixtures
6. A process as claimed in claim 5, wherein the optional solvent is present in the
solvent at a level of from 8 to 15 wt%.
7. A process as claimed in any one of the preceding claims, wherein the polymer has
a molecular weight in the range of from 2000 to 4500 Daltons.
8. A process as claimed in any one of the preceding claims, wherein the anti-fouling
polymer is a block copolymer having general formula (I) or (II):
R'-(CH2-CH2-O)k-(CH2-CH(R)-O)n -(CH2-CH2-O)m-R" (1)
or R'-(CH2-CH(R)-O)a-(CH2-CH2-O)b-(CH2-CH(R)-O)c-R" (11)
where R comprises an alkyl group; R' and R" are end groups as defined in claim 1; k
is from 1 to 50; n is from 1 to 50; m is greater than or equal to 1; a is from 1 to 50; b
is from 1 to 50; and c is from 0 to 50.
9. A process as claimed in claim 8, wherein the anti-fouling polymer is a block
copolymer having general formula (III):
R'-(CH2-CH2-O)k-(CH2-CH(CH3)-O)n -(CH2-CH2-O)m-R" (III)
where R', R", k, n, and m independently are as defined in claim 8.
10. A process as claimed in claim 9, wherein the anti-fouling polymer is a block
copolymer having general formula (IV):
OH-(CH2-CH2-O)k-(CH2-CH(R)-O)n -(CH2-CH2-O)m-H (IV)
where R, k, n, and m independently are as defined in claim 8.
11. A process as claimed in any one of the preceding claims, wherein the process is
carried out in at least one loop reactor.
12. A process as claimed in claim 11, wherein the process is carried out in a double
13. A process as claimed in any one of the preceding claims, wherein the process is
carried out at a temperature in the range from 40 to 110°C.
14. A process as claimed in any one of the preceding claims, wherein the process is
carried out at a pressure in the range from 5 to 200 barg.
15. A process as claimed in any one of the preceding claims, wherein the process is
carried out in the presence of a metallocene catalyst.
16. A process as claimed in any one of the preceding claims, wherein the process is
for making a homopolymer of propylene.
17. A process as claimed in any one of claims 1 to 15, wherein the process is for
making a copolymer of propylene.
The invention discloses a propylene polymerisation process carried out in the
presence of an anti-fouling agent; characterised in that the anti-fouling agent
comprises an anti-fouling polymer containing: (1)one or more blocks -(CH2-CH2-O)k-
where each k is in the range from 1 to 50; and (2)one or more blocks -(CH2-CH(R)-
O)n- where R comprises an alkyl group having from 1 to 6 carbon atoms and each n
is in the range from 1 to 50; and terminated by a R' and a R" end groups wherein R'
is OH or an alkoxy having from 1 to 6 carbon atoms and R" is H or an alkyl having
from 1 to 6 carbon atoms; and the anti-fouling polymer is solvated in a solvent
comprising cyclohexane when added to the polymerisation medium.
|Indian Patent Application Number||1970/KOLNP/2006|
|PG Journal Number||24/2012|
|Date of Filing||13-Jul-2006|
|Name of Patentee||TOTAL PETROCHEMICALS RESEARCH FELUY|
|Applicant Address||ZONE INDUSTRIELLE C, B-7181 SENEFFE (FELUY)|
|PCT International Classification Number||C08F 10/00|
|PCT International Application Number||PCT/EP2005/050527|
|PCT International Filing date||2005-02-08|