Title of Invention

PROCESS FOR PRODUCING OLEFIN POLYMERS

Abstract The invention discloses a process for producing at least two different propylene polymer grades, in which process the isotacticity of the polymer is changed while keeping the melt flow rate of the polymer at a predetermined level during a transition of production from a first polymer grade having a predetermined MFR to a second polymer having the same predetermined MFR, said process being carried out in a polymerization arrangement comprising at least one polymerization reactor, where propylene is polymerized, optionally with comonomers, under polymerization conditions in the presence of hydrogen as a molecular weight controlling agent and a Ziegler-Natta catalyst system, comprising a catalyst component and a first and a second external donor, respectively, characterized in that the first external donor is changed to the second, but the hydrogen feed is kept at a predetermined level, during a transition of production from the first polymer grade to the second and wherein the catalyst system comprises a catalyst component prepared according to a liquid-liquid two phase emulsion method.
Full Text A PROCESS FOR PRODUCING ATLEAST TWO DIFFERENT
GRADES OF PROPYLENE POLYMER
Background of the Invention
Field of the Invention
The present invention relates to olefin polymerization. In particular, the present invention
concerns a process for polymerization of propylene in a polymerization reactor arrangement
to produce at least two olefin polymers having essentially the same level of Melt Flow Rate
but different isotacticity.
Description of Related Art
Polypropylenes are conventionally produced in the presence of a high-yield catalyst system
comprising a catalyst component, a cocatalyst component and a compound acting as an
external electron donor. The catalyst component is typically a supported Ziegler-Natta type
catalyst containing magnesium, titanium and a halogen as essential components. Porous,
inorganic or organic particulate carrier materials, such as silica or MgCh supports, are used as
support materials. The external electron donors present a means for controlling the isotacticity
of the polymer.
For different applications, polymers with very different properties are required. The main
characteristics of these polymers are their isotacticity and Melt Flow Rate, in the following
also abbreviated "MFR", These features can be controlled by varying the process conditions
and by using different catalyst systems. One important tool for adapting the properties of the
polymers to varying product requirements is adjustment of hydrogen feed during
polymerization. By varying of the feed of hydrogen, the molecular weight or MFR of the
polymer can be controlled. The stiffness of the polymer is also an important product property,
which should be adjusted depending on the end use of the polymer. Stiffness is greatly
dependent on the isotacticity of the polymer and, thus, isotacticity has to be set at the desired,
predetermined level. This is typically done by proper selection of the external donors used in
the polymerization process.
It is commonly known that different external donors lead to polymers with different
isotacticities and to polymers having different mechanical properties. One of the important
mechanical properties is the flexural modulus. It is also known that the isotacticity can be
affected to some extent by changing the concentration of the donor. This change in donor
concentration influences the concentration of xylene-solubles of the polymer, which is usually
not desired.
There are problems related to the known processes, when transitions from one polymer grade
to another grade have to be made. It is often necessary to produce different polymer grades
with the same process equipment. With prior art processes it is extremely difficult, and
sometimes even impossible, to change over from one polymer grade to another by changing
one polymer characteristic without affecting the other polymer characteristics. According to
the prior art, the change in one feature or one component of the process tends to cause
changes in other features, too. This means in practice that if one component or feature in a
process for changing one property of the product is changed, then one or more other
components of the process have to be changed, too, if the other properties of the polymer are
to be kept unchanged. This is due to the fact that components of the process are so closely
linked together that changes in one component mean changing the others, too. This is a great
problem with present-day processes, where the transition of polymer grades having different
stiffness, but a predetermined MFR has to be made.
As is stated above, different isotacticity levels require the use of different external donors.
However, hydrogen response of the catalyst system is dependent on the type of external
donors used. "Hydrogen response" or "hydrogen sensitivity" stands for the sensitivity of the
molecular weight of the polymer to the hydrogen concentration. This means that if the
external donor is changed, the hydrogen feed to the process needs to be recalculated and
changed in order to meet the requirements for a specific level of melt flow rate. As far as the
process is concerned, this causes extra work, time and costs.
Thus, in summary, according to known processes, when isotacticity and MFR of the polymer
are modified, the donor needs to be changed and the hydrogen flow to the process needs to be
altered. Even if only isotacticity is to be changed by changing the donor, also the hydrogen
feed has to be changed due to the reasons explained above. Further, there is always a
transitional period of time before the grade of the polymer product is changed from a first
polymer grade to another, since conventional processes stabilize slowly after a change of
donor and hydrogen feed. The material produced during the switching-over period between
two grades often has to he discarded because it does not fulfil the quality requirements neither
of the first nor of the second polymer. This is both an economical and an environmental
disadvantage.
Until now, no method of transition from one polymer grade to another is known, wherein the
hydrogen feed could be kept on the same level when an external donor is changed, in order to
change the isotacticity, but to keep the JvIFR at the predetermined level. In practice, this
means that there are no processes that would allow for facile transition from one polymer
grade to another having different isotacticity but essentially the same MFR.
Summary of the Invention
It is an aim of the present invention to eliminate the problems of the prior art and to provide a
novel way of producing two or several grades of propylene polymers, including propylene
homo- and copolymers, in one and the same polymerisation reactor system, while avoiding
extended transitional periods between the change from one grade to another.
It is another object of the invention to provide a propylene polymerization process, where the
control of isotacticity and MFR of the propylene polymer can be optimised during the
production of propylene homopolymers and/or propylene copolymers comprising propylene
random and heterophasic (block) copoljoners.
Furthermore, a third object of the invention is to provide a process, where the sensitivity of
the molecular weight of the polymer to the hydrogen concentration (i.e. hydrogen response or
sensitivity of the catalyst) is increased. Such a process will provide for a novel means of
controlling isotacticity of polypropylene polymers primarily only by using external donors.
These and other objects, together with the advantages thereof over known processes and
products, are achieved by the present invention as hereinafter described and claimed.
The invention is based on the surprising finding that a specific, newly-developed kind of
catalysts can be used for producing, at essentially the same polymerization conditions,
different polymers having the same, predetermined level of MFR but different isotacticity.
These new catalysts will allow for the same hydrogen response while using different external
donors.
Typically, the catalysts comprise particles of Group 3 to 10 transition metal compounds, or an
actinide or lanthanide, in combination with compounds or complexes of Group 2 metals,
produced by solidification of particles from emulsion systems to produce catalyst particles
having a desired particle size. In particular, the catalyst particles are obtained by fomiing a
liquid-liquid emulsion system, which contains a homogeneous solution of the at least one
catalyst component, said solution being dispersed in a solvent immiscible therewith and
forming the dispersed phase of the liquid-liquid emulsion system, solidifying said dispersed .
droplets to form solid catalyst particles having a predetermined size range, and recovering
said solid catalyst particles. The particles are "self-supporting" in the sense that they are not
supported on any external carrier. An essential feature of the obtained catalyst is that the
active sites of the catalyst are evenly distributed thorough the whole particles contrary to the
normally used commercial supported ZN catalysts, where the surface of an external support is
treated with the catalyst, whereby the active sites of the catalyst are concentrated only on the
surface of the support or carrier.
These novel kinds of catalysts and their preparation are described in WO Publications Nos.
03/000754 and 03/000757, the contents of which are herewith incorporated by means of
reference.
The above-described catalysts can, according to the present invention, now be used in a novel
transition process for producing at least two different propylene polymer grades, in which
process the isotacticity of the pol>Tner is changed while keeping the melt flow rate of the
pol>'mer at a predetermined level during a transition of production - in particular continuous
production - from a first polymer grade to a second, said process being carried out in a
polymerization arrangement comprising at least one polymerization reactor, where propylene
is polymerized, optionally with comonomers, under polymerization conditions in the presence
of hydrogen as a molecular weight controlling agent and a Ziegler-Natta catalyst system,
comprising a catalyst component and an external donor, wherein the external donor is
changed, but the hydrogen feed is kept at a predetermined level, during a transition of
production from the first polymer grade to the second.
In practice, the production of the first pol^Tner grade is carried out in the presence of a catalyst
system comprising a first external donor and the production of the second polymer gi'ade is
carried out in the presence of a catalyst system comprising a second (different) extemal donor.
According to the invention, the change of the extemal donor comprises exchanging the first
extemal donor for the second extemal donor.
The above-described catalysts can also be used in a process for producing at least two olefin
polymers having essentially the same level of IVIFR but different isotacticity, by polymerizing
the olefin monomers in the presence of the catalytic system and by maintaining the hydrogen
feed at an essentially constant level during the production of at least the first and the second
polymers.
Further, the catalysts provide for a process of controlling the isotacticity of polypropylene
polymers by using extemal donors, in which process the isotacticity is adjusted by changing
the extemal donor without changing the hydrogen feed and still maintaining the melt fiow rate
essentially at the same level.
More specifically, the process according to the present invention is mainly characterized by
what is stated in the characterizing part of claims 1,7 and 25.
The present invention provides important advantages. Thus, the present invention makes it
faster and easier to control the overall process and especially to change from one polymer
grade to another, while maintaining good control over the important properties, like MFR and
isotacticity, of the polymer product. As pointed out above, with known processes, transfer
from producing one polymer grade having a predetermined MFR level to produce another
polymer grade having the same MFR level but different isotacticity is often difficult. The
hydrogen feed has to be changed and this operation will lead to a lowered production rate in
order to decrease the off-spec material, the amount of which might be undesired high in
conventional processes. This is, as stated above, due to the fact that a change from one
extemal donor to another leads to different hydrogen response and, thus, to necessary changes
in hydrogen feed. This is, however, not necessary for the invention. On the contrary, it is an
essential and important feature of the invention that the hydrogen feed can be maintained on
essentially the same (predetermined or preset) level during the entire operation of the
polymerization process comprising the change of the external donor for producing two or
more polymers having different isotacticity but the same MFR.
Another great advantage is that the transition from one grade of polymer to another is faster
and easier, because there is no need to alter the hydrogen feed to the process. In other words,
the hydrogen feed curves do not have to be recalculated and reoptimized when the polymer
grade is changed. There will be less rejected material that does not fulfil product
requirements, because the target level of product properties is reached sooner. This is an
advantage when thinking of both economical (lower operational cost) and environmental
aspects. In addition to this, a broader product window can be reached much easier.
A further problem associated with prior art processes is that the final stages of product
development are time-consuming and expensive. New grades have to be tested at real process
conditions using real process equipment. With the help of the present invention, product
development will be faster. Product development involves testing new polymer grades and
often involves switching from one donor to another. With prior art processes, this means
changing the hydrogen flow. With help of the present invention, the time requirement for the
switch is shorter, because there is no need to alter the hydrogen feed to the process.
In polymerization processes, control systems play an important role. For prior art processes,
there are many variables to control. One of them is the hydrogen feed, which usually needs to
be altered when polymer grades are changed. The more variables there are to control, the
more difficult it is to reach the desired properties when the variables are changed. In other
words, there is more off grade produced. Also transition times are longer with additional
parameters to be changed in product change. The present invention allows for easier control
of the overall process because there is one variable less to control and may lead to lower
investment cost.
With the aid of the present invention, it is possible to produce a wider product range or
product window with the same process. By using the process of the present invention, it is
possible to produce propylene polymers having a Melt Row Rate OIFR2) 0.01 to 1500 g/10,
min or even higher, (measured by ISO Standard 1133, at 230 °C, 2.16 kg load) and isotacticity
in the range, which is normally obtainable by donors used in the propylene polymerization
processes.
Hydrogen feed is maintained at essentially constant level, when making polymer with same
MFR, but by using different extemaJ donor, i.e. the feed is independent on the donor. For the
purpose of this invention, "essentially constant level" means that the volume of the hydrogen
feed will change at the most 5 % from the starting volume. The level of the hydrogen feed is
chosen to produce polymers with desired MFR. Further details and advantages of the
invention will become apparent from the following detailed description comprising a number
of working examples.
Brief Description of the Drawings \^
Figure 1 depicts graphically the results of polymerization experiments disclosed in Examples
1, 2 and 5 according to the invention. The x-axis represents hydrogen flow and the y-axis
MFR2 of the polymer.
Figure 2 depicts graphically the result of polymerization experiments of Comparative
Examples 1, 2 and 3. The x-axis represents hydrogen flow and the y-axis MFR2 of the
polymer.
Detailed Description of the Invention
Overall Process
Generally, the present invention comprises the steps of producing
- a first polymer or polymer grade with a predetermined MFR and a first degree of
isotacdcity in the presence of said catalytic system using a first external donor; and
- a second polymer or polymer grade with essentially the same predetermined \iFR
and a second degree of isotacticity in the presence of said catalytic system using a
second external donor. The second donor can be the same as or, preferably,
different from the first donor.
The process steps can be performed in optional order and in a sequence one after another. The
process can be a one stage or a multistage polymerization process carried out in liquid/slurry
phase, gas phase or vapour phase in a sequence of polymerization steps comprising one or
more liquid/slurry polymerization and/or one or more gas phase polymerization steps or
combinations thereof in any order. The polymerization in each stage can be carried out in one
or more reactors such as slurry/bulk polymerization reactors and or gas phase reactors. In one
embodiment the polymerization is carried out in at least one bulk reactor, preferably loop
reactor, followed by at least one gas phase reactor.
Polymers
The polymers produced with the process of the invention are propylene polymers comprising
propylene homopolymers, propylene copolymers comprising propylene random and
heterophasic (block) copolymers or combinations thereof.
The comonomers used are selected from the group of C2-18 olefins, preferably C^.k) olefins,
such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-l-pentene, 1-heptene, 1-octene, 1-
nonene and 1-decene as well as mixtures thereof and dienes, such as 1,5-hexadiene and 1,9-
decadiene. Most commonly used comonomers are ethylene and 1-butene, especially ethylene.
By using the process of the present invention, it is possible to produce propylene polymers
having a Melt Flow Rate (MFR2) of 0.01 to 1500 g/10 min or even higher, preferably 0.1 to
500 g/10 min, in particular 10 to 300 g/min, (measured by ISO Standard 1133, at 230 °C, 2.16
kg load). As examples of some particularly preferred ranges the following can be mentioned
(measured as explained above): 20 to 200 g/min, 20 to 100 g/min, 50 to 150 g/min and 100 to
300 g/min, depending on the final application. FllR Isotacticity (measured by FTIR , Fourier
transform infrared spectra, "C NMR calibrated ) depends, as is well known, on the MFR of
the polymer. As examples of the higher FTIR isotacticity-values of homoPP produced by the
process of the invention are e.g. as follows: at MFR2 of 0,3 g/10 min about 91 %, at MFR2 of
20 g/10 min about 99 % and at MFRaof 300 g/10 min about 103 %. Lower isotacticity
(= higher XS), at a certain MFR-level, can be achieved by decreasing donor concentration or
by using a weaker external donor in the polymerisation. However, changing the donor
concentration will also change the hydrogen sensitivity of the catalyst system, which causes a
need to alter also hydrogen feed. In this case, two changes in the process are needed. If the
lower isotacticity is achieved by changing the external donor, only one change in the process
is needed, because hydrogen sensitivity of the catalyst system does not change even if the
external donor is changed.
According to the present invention, a smooth transition from one grade of polymer to another
grade is now possible;.polymers having the same MFR level but different isotacticities can be
obtained without changing the hydrogen feed from the polymerization of the first polymer to
the following polymer(s). The process provides continuous polymerization of propylene
monomers along with any possible comonomers using a catalyst having essentially the same
hydrogen response independent on the used external donors. This means that the catalyst used
exhibits the same hydrogen response and, thus, the MFR of the polymers will remain
essentially unchanged, although different isotacticities are desired and obtained. As a result,
the switch or transition from one grade to another will be facile and rapid, resulting in no or
only minor losses in production output during the transition period.
According to an embodiment of the invention a first polymer is produced, having a
predetermined MFR and a lower isotacticity and a second polymer is produced having the
same MFR but a higher isotacticity. This sequence can be followed by a third and a founh and
several further polymers having even higher or again lower isotacticities than any of the
previous polymers.
According to another embodiment, the isotacticity of the second polymer may be lower than
that of the first polymer. This sequence can be followed by a third and a fourth and several
further polymers having even lower or again higher isotacticities than any of the previous
polymer.
Reactors
The poljTTierization reactor arrangement comprises one or more liquid/slurry/ reactor(s),
preferably bulk reactor(s), or one or more gas phase reactor(s), or combinations of any of
these in any order. The reactors can be arranged in series. The polymerization may be carried
out in several stages each comprising polymerizations in one or more reactors.
The first stage polymerization can be carried out in one or more bulk reactor(s), preferably
loop reactor, or in one or more gas phase reactor(s). Typically, the reactors are connected in
series. The second stage polymerization is preferably carried out in one or more gas phase
reactor(s). The second stage polymerization is typically carried out essentially immediately
after the first stage polymerization, i.e., the polymerization product recovered from the first
polymerization stage is conducted to the first gas phase reactor of the second polymerization
stage. The gas phase reactors in the second polymerization stage are preferably connected in
series.
The polymerization temperature in the actual polymerizations is usually in the range of 60 to
i 10 °C, preferably between 70 and 100 °C, more preferably between 70 and 90°C and most
preferably between 70 and 85°C. The pressure in the slurry/bulk reactors, preferably in loop
reactors is typically between 20 to 70 bar, preferably between .30 to 60 bar. The pressure in
the gas phase reactors is typically between 10 to 40 bar, preferably 15 to 30 bar.
According to one embodiment, the heterophasic propylene copolymer is produced in a
reactor system comprising at least one liquid (bulk) reaction stage including at least one
liquid (bulk) reactor, preferably at least one loop reactor, and at least one gas phase
reaction stage including at least one gas phase reactor. The reactors are connected in series,
the bulk reactors being preferably arranged before the gas phase reactors. A separation
stage can be employed between the reaction stages or reactors to prevent the carryover of
reactants from the one polymerization stage or reactor into another.
According to this embodiment the polymer matrix is produced in the first reaction stage,
which is preferably a bulk reaction stage, and the heterophasic rubbery part is produced in
the second reaction stage, which preferably is a gas phase reaction stage.
In addition to the actual pol)'merization reactors used, the polymerization reaction system can
also include a number of additional reactors, such as prereactors. The prereactors include any
reactor for preactivating and/or prepolymerizing the catalyst e.g. with propylene and/or other
a-olefin(s) and/or ethylene, if necessary. In addition the polymerization system can contain
some post-reactors for further modifying the produced polymer. All reactors in the reactor
system are preferably arranged in series.
According to the invention, it is not necessary to change the hydrogen feed to keep the MFR
of the polymer at the predetermined level, although adjustment of the isotacticity is aimed at,
e.g. by changing the external donor used to another type of donor. I.e. the hydrogen feed can
be maintained at an essentially constant level in the polymer transition process. For the
purpose of this invention, "essentially constant hydrogen feed level" means that during the
transition from a first polymer to another, the predetermined MFR can be maintained and the
desired isotacticity of the second or further polymer can be reached without altering the
volume of the hydrogen feed. Keeping the hydrogen feed essentially at the same level, means
that it will be changed no more than 5 %, preferably no more than 3 %, most preferably no
more than 2 %, from the starting volume. The level of the hydrogen feed is chosen so as to
enable production of a first polymer with a desired MFR and isotacticity and a second or
following polymers with the same, predetermined MFR but different isotacticity.
The catalyst
The catalyst system comprises a catalyst component, optionally a procatalyst component and
a cocatalyst component, and an external donor.
The external donors used in the present invention are strongly coordinating donors, which
form relatively strong complexes with catalyst surface, mainly with MgClz surface in the
presence of aluminium alkyl and TiCU. The donor components are characterised by a strong
complexation affinity towards catalyst surface and a sterically large and protective
hydrocarbon. Strong coordination with MgCIz requires oxygen-oxygen distance of 2.5 to 2.9
A [Albizzati et al., Macromol. Symp. 89 (1995) 73-89].
Typically this kind of donors are silane-based donors having the structure of the general
formula I
R"'nSi(OMeV„ (D
wherein R"' is a branched aliphatic or cyclic or aromatic group. Me stands for methyl and n is
1 or 2, preferably 2. [Harkdnen et al., Macromol. Chem. 192 (1991) 2857-2863].
In particular, the external donor is selected from the group consisting of dicyclopentyl
dimethoxysilane (donor D), cyclohexylmethyl dimethoxy silane (donor C), diisopropyl
dimethoxysilane, methylcyclohexyidimethoxy silane, di-isobutyl dimethoxysilane, and di-t-
butyl dimethoxysilane. Dicyclopentyl dimethoxysilane (donor D) and cyclo hexyl methyl
dimethoxy silane (donor C) are particularly preferred. From these donors D and C, donor D
has, according to common knowledge, a stronger coordinating effect than donor C.
The present catalyst system comprises catalyst particles, which, according to the present
invention, are of a specific constitution in the sense that they are not supported on any
external carrier contrary to the normally used commercial supported ZN catalysts. The active
sites of the catalyst are evenly distributed throughout the whole particles and the particles are
"self-supporting". Catalysts of this kind can be prepared as described in WO Publications
Nos. 03/000754 and 03/000757.
In addition to the above-discussed features, the catalyst particles prepared according to the
cited documents have excellent morphology and good, uniform particle size distribution and
due to the replica effect the polymer particles produced by using these catalysts have veiy
good morphology properties, too.
The olefin polymerization catalyst component used in the present invention, comprises a
compound of a transition metal of Group 3 to 10 of the Periodic Table (TUPAC), or of an
actinide or lanthanide, and is prepared according to a method comprising
(a) forming a liquid/liquid two phase emulsion system, which contains a homogeneous
solution of at least one catalyst component, said solution being dispersed in a liquid
medium and forming the dispersed phase of the liquid/liquid emulsion system,
(b) solidifying said dispersed droplets to form solid catalyst particles having a
predetermined size range,
(c) recovering the obtained solidified catalyst particles.
As regards the "predetermined size range", it should be noted that the catalyst particles
usually have an average size in the range of 5 to 200 |im, preferably 10 to 100, more
preferably 20 to 50 |im.
The catalyst component can include, in addition to said transition metal compound, also any
additional cocatalyst(s) (e.g. additional transition metal compounds) and/or activators and/or
poison scavengers) and/or any reaction product(s) of a transition compound(s) and a
cocatalyst(s). Thus the catalyst may be formed in sitii from the catalyst components in said
solution in a manner disclosed in said references.
A preferred process for producing an ZN propylene polymerization catalyst component in the
form of particles having a predetermined size range comprises preparing a solution of a
complex of a Group 2 metal and an electron donor by reacting a compound of said metal with
said electron donor or a precursor thereof in an organic liquid reaction medium; reacting said
complex, in solution, with a compound of a transition metal to produce an emulsion, the
dispersed phase of which contains more than 50 mol-% of the Group 2 metal in said complex;
maintaining the particles of said dispersed phase within the average size range 5 to 200 um by
agitation preferably in the presence of an emulsion stabilizer and solidifying said particles;
recovering and optionally washing said particles to obtain said catalyst component.
For said ZN catalyst particles, the compound of a transition metal is preferably a compound of
a Group 4 metal. The Group 4 metal is preferably titanium, and its compound to be reacted
with the complex of a Group 2 is preferably a halide. In a still further embodiment of the
invention a compound of a transition metal can also be selected from Group 5 metals, Group
6 metals, Cu, Fe, Co, Ni and/or Pd. Tlie complex of the Group 2 metal is preferably a
magnesium complex.
The liquid medium used in the formation of the liquid/liquid two phase emulsion system is a
medium being immiscible to the solution of at least one catalyst component at least to the
extent that an emulsion can be formed.
In a preferred embodiment the process for producing catalysts used in the invention
comprises: preparing a solution of magnesium complex by reacting an alkoxy magnesium
compound and an electron donor or precursor thereof in a Ce-Cio aromatic liquid reaction
medium; reacting said magnesium complex with a compound of at least one four-valent
Group 4 metal at a temperature greater than 10 °C and less than 60 'C, to produce an
emulsion of a denser, TiCWtoluene-insoluble, oil-dispersed phase having. Group 4 metal/Mg
mol ratio 0.1 to 10 in an oil disperse phase having Group 4 metal/Mg mol ratio 10 to 100;
maintaining the droplets of said dispersed phase within the size range 5 to 200 pm by
agitation in the presence of an emulsion stabilizer while heating the emulsion to solidify said
droplets and adding turbulence minimizing agent into the reaction mixture before solidifying
said droplets of the dispersed phase, said turbulence minimizing agent being inert and soluble
m the reaction mixture under the reaction conditions; and recovering the obtained olefin
polymerization catalyst component. The recovering step comprises removal of the solvent
from the mixture, which can be done e.g. by drying or by other means.
In the above, the term "oil-dispersed phase" means that the phase containing the catalyst
component(s) is an oil-like liquid.
The turbulence minimizing agent (TMA) or mixtures thereof preferably comprises
polymers having linear aliphatic carbon backbone chains, which might be branched with
short side chains only in order to serve for uniform flow conditions when stirring. Said
TMA is in particular preferably selected from a-olefin polymers having a high molecular
weight of MW about 1 - 40 x 10 , or mixtures thereof. Especially preferred are polymers
of a-olefin monomers with 6 to 20 carbon atoms, and more preferably polyoctene,
polynonene, polydecene, polyundecene or polydodecene or mixtures thereof, having the
molecular weight and general backbone structure as defined before, and most preferable
TMA is polydecene.
As electron donor compound to be reacted with the Group 2 metal compound is preferably
an mono- or diester of an aromatic carboxylic acid or diacid, the latter being able to form a
chelate-like structured complex. Said aromatic carboxylic acid ester or diester can be
formed in situ by reaction of an aromatic carboxylic acid chloride or diacid dichloride with
a C2-C16 alkanol and/or diol, and is preferable dioctyl phthalate, such as di-ethyl-hexyl
phthalate. The liquid reaction medium preferably comprises toluene.
The reaction for the preparation of the Group 2 metal complex is generally carried out at a
temperature of 20° to 80°C,, and in case that the Group 2 metal is magnesium, the
preparation of the magnesium complex is carried out at a temperature of 50° to 70°C.
The emulsion stabiliser is typically a surfactant, of which the preferred class is that based on
acrylic polymers.
The alkoxy magnesium compound group is preferably selected from the group consisting of
magnesium dialkoxides, complexes of a magnesium dihalide and an alcohol, and complexes
of a magnesium dihalide and a magnesium dialkoxide. It may be a reaction product of an
alcohol and a magnesium compound selected from the group consisting of diaJkyl
magnesiums, alkyl magnesium alkoxides, alkyl magnesium haiides and magnesium dihalides.
It can further be selected from the group consisting of dialkyloxy magnesiums, diaryloxy
magnesiums, alkyloxy magnesium haiides. aryloxy magnesium haiides, alkyl magnesium
alkoxides, aryl magnesium alkoxides and alkyl magnesium aryloxides.
The magnesium dialkoxide may be the reaction product of a magnesium dihalide such as
magnesium dichloride or a dialkyl magnesium of the formula R2Mg, wherein each one of the
two R's is a similar or different C1-C20 alkyl, preferably a similar or different C4-C10 alkyl.
Typical magnesium alkyls are ethylbutyl magnesium, dibutyl magnesium, dipropyl
magnesium, propylbutyl magnesium, dipentyl magnesium, butylpentylmagnesium, butyloctyl
magnesium and dioctyl magnesium. Most preferably, one R of the formula R2Mg is a butyl
group and the other R is an octyl group, i.e. the dialkyl magnesium compound is butyl octyl
magnesium.
Typical alkyl-alkoxy magnesium compounds RMgOR, when used, are ethyl magnesium
butoxide, butyl magnesium pentoxide, octyl magnesium butoxide and octyl magnesium
octoxide.
Dialkyl magnesium, alkyl magnesium alkoxide or magnesium dihalide can react with a
polyhydric alcohol R'(OH)m, or a mixture thereof with a monohydric alcohol R'OH.
Typical C? to Q polyhydric alcohols may be straight-chain or branched and include ethylene
glycol, propylene glycol, triraethylene glycol, L2-butylene glycol, 1,3-butylene glycol, 1,4-
butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, pinacol,
diethylene glycol, triethylene glycol, and triols such as glycerol, methylol propane and
pentareythritol. The polyhydric alcohol can be selected on the basis of the acdvity and
morphology desired to the catalyst component.
The aromatic reaction medium may also contain a monohydric alcohol, which may be
straight- or branched-chain. Typical Ci -C20 monohydric alcohols are methanol, ethanol, n-
propanol, iso-propanol, n-butanol, iso-butanol, sec.butanoi, tert.butanol, n-amyl alcohol, iso-
amyl alcohol, sec.amyl alcohol, tert.amyl alcohol, diethyl carbinol, akt. amyl alcohol, sec.
isoamyl alcohol, tert.butyl carbinol. Typical Ce-Cio monohydric alcohols are hexanol, 2-ethyl-
Ibutanol, 4-methyl-2-pentanol, 1-heptanol, 2-heptanol, 4-heptanoI, 2,4-dimethyl-3pentanol, 1-
octanol, 2-octaiiol, 2-ethyI-l-hexanoI, 1-nonanol, 5-nonanol, dilsobutyl carbinol, 1-decanol
and 2,7-dimethyl-2-octanol. Typical >Cio monohydric alcohols are n-1-undecanol, n-1-
dodecanol, n-1-tridecanol, n-1-tetradecanoI, n-l-pentadecanol,l-hexadecanol, n-l-
heptadecanol and n-1 octadecanol. The monohydric alcohols may be unsaturated, as long as
they do not act as catalyst poisons.
Preferable monohydric alcohols are those of formula R'OH in which R' is a C2-CI6 alkyl
group, most preferably a C4-C1: alkyl group, particularly 2-ethyl-l-hexanol.
Preferably, essentially all of the aromatic carboxylic acid ester is a reaction product of a
carboxylic acid halide, preferably a dicarboxylic acid dihalide, more preferably an unsaturated
a,6-dicarboxylic acid dihalide, most preferably phthaUc acid dichloride, with the monohydric
alcohol.
The finally obtained catalyst component is desirably in the form of particles having an
average size range of 5 to 200 |jm, preferably 10 to 100, more preferably 20 to 50 |am and the
active sites of the catalyst are evenly distributed in the whole catalyst particle.
The catalyst used in the present invention comprises a catalyst component prepared as
aforesaid, in association with commonly used cocatalysts, preferably alkyl aluminium
compounds, more preferably aluminium trialkyls or aluminium alkyl halids, most preferably
trialkyl aluminium, such as triethyl aluminium and external donors, and is used for the
polymerization of propylene optionally with other monomers, such as C2 to Cio-olefins.
Summarising what has been stated above, one particularly preferred embodiment of the
invention comprises a process for controlling isotacticity of polypropylene polymers by using
external donors, comprising
- feeding propylene together with optional comonomers along with hydrogen as a
molecular weight controlling agent and a Ziegler-Natta catalyst system, including a
catalyst component having as essential components Ti, Mg and CI cocatalyst, and an
external donor, into a polymerization reactor arrangement formed by at least one
polymerization reactor and
polymerizing propylene together with the optional monomers under poliTnerization
conditions in order to obtain a polymer product having a predetermined melt flow rate
and isotacticity,
wherein isotacticity is adjusted by changing the external donor without changing the hydrogen
feed and still maintaining the melt flow rate essentially at the same level.
The following non-limiting examples illustrate the invention in more detail:
Examples
In the examples, the following measurement methods were used:
MFR (Melt flow rate) : ISO 1133, 230 °C, 2,16 kg load
XS (Xylene solubles) : xylene soluble part at 25 °C , ISO 6427
Tm (Melting temperature): Differential scanning calorimetry, DSC, Mettler TA 820
FTIR isotacticity : Fourier tranformed infrared spectra, '"'C NMR calibration
FLEXULAR M0DU1.US : ISO 178
Example la
All raw materials were essentially free from water and air and all material additions to the
reactor and the different steps were done under inert conditions in nitrogen atmosphere. The
water content in propylene was less than 5 ppm.
The polymerization was done in a 5 litre reactor, which was heated, vacuumed and purged
with nitrogen before taken into use. 348 |Lil TEA (triethyl aluminium from Witco used as
received) as cocatalyst, 51 |i.l donor C (cyclo hexyl methyl dimethoxy silane from Wacker,
dried with molecular sieves) and 30 ml pentane (dried with molecular sieves and purged with
nitrogen) were mixed and allowed to react for 5 minutes. Half of the mixture was added to the
reactor and the other half was mixed with 17,2 mg highly active and stereospecific Ziegler
Natta catalyst (ZN catalyst). The ZN catalyst was prepared according to WO03/000754,
example 7 and had Ti content 2.84 w-%. After about 10 minutes the ZN catalyst/TEA/donor
C/pentane mixture was added to the reactor. The Al/Fi molar ratio was 250 and the Al/Do
(Al/extemal donor) molar ratio was 10.
300 mmol hydrogen and 1400 g propylene were added to the reactor. The temperature was
increased from room temperature to 70 °C during 20 minutes. The reaction was stopped, after
60 minutes at 70 °C, by flashing out unreacted propylene. Finally, the polymer powder was
taken out from the reactor and analysed and tested. The MFR of the product was 17. The
details and results are shown in Table 1.
Example lb
This example was carried out in accordance with Example la, with the exception that donor
D (dicyclo pentyl dimethoxy silane) was used as external donor. The MFR of the product was
20, which is practically the same as that obtained with donor C in Example la. The details
and results are shown in Table 1.
Example 2a
This example was carried out in accordance with Example la, with the exception that the
amount of hydrogen was 1500 mmol. The MFR was 280 g/lOmin. The details and results are
shown in Table 1.
Example 2b
This example was carried out in accordance with Example 2a, with the exception that donor
D was used as external donor. The MFR was 290, which is practically the same as with donor
C in Example 2a. The details and results are shown in Table 1.
Example 3a
This example was carried out in accordance with example la, with the exception that Al/Do
ratio was 50. The MFR was 31. The details and results are shown in Table 1.

Example 3b
This example was carried out in accordance with Example 3a, with the exception that
donor D was used as external donor. The MFR was 30, which practically is the same as
obtained with donor C in Example 3a. The details and results are shown in Table 1.
Example 4a
This example was carried out in accordance with Example la, with the exception that the
temperature in polymerization was 80 °C, The MFR was 24. The details and results are
shown in Table 1.
Example 4b
This example was carried out in accordance with Example 4a, with the exception that
donor D was used as external donor. The MFR was 23, which is practically the same as in
Example 4a, where donor C was used. The details and results are shown in Table 1.
Example 5a
This example was carried out in accordance with Examplela, with the exception that the
amount of hydrogen was 6 mmol. The MFR was 0.32 g/lOmin. The details and results are
shown in Table 1.
Example 5b
This example was carried out in accordance with Example 5a, with the exception that
donor D was used as external donor, hydrogen amount was 7 mmol and poljonerization
temperature was 75 °C. The MFR was 0.32, which is practically the same as in example
5a, where donor C was used. The details and results are shown in Table 1.
Comparative Example la
This example was carried out in accordance with Example la, with the exception that the
hydrogen amount was 13 mmol, polymerization temperature 80 °C, donor D was used as
external donor and a different catalyst was used. The catalyst used in this test was a
transesterified MgCh supported Ziegler Natta catalyst with Ti-content of 2,1 % for
producing high stiffness polypropylene products. The catalyst was prepared in accordance
with Finnish patent No. 88047. The MFR of the polymer was 0,36. The details and results
are shown in Table 2.
Comparative Example lb
This example was carried out in accordance with Comparative Example la, with the
exception that donor C was used as external donor. The MFR was 0,70, which is 100 %
higher than MFR in comparative example la, where donor D was used. The details and
results are shown in Table 2.
Comparative Example 2a
This example was carried out in accordance with Comparative Example la, with the
exception that the hydrogen amount was 200 mmol and polymerization time was 30
minutes. The MFR was 5.3. The details and results are shown in Table 2.
Comparative Example 2b
This example was carried out in accordance with Comparative Example 2a, with the
exception that donor C was used as external donor. The MFR was 16.9, which is 300 %
higher than MFR in Comparative Example 2a, where donor D was used. The details and
results are shown in Table 2.
Comparative Example 3a
This example was c£irried out in accordance with Comparative Example la, with the
exception that the hydrogen amount was 1500 mmol. The MFR was 210. The details and
results are shown in Table 2.
Comparative Example 3b
This example was carried out in accordance with Comparative Example 3a, with the
exception that donor C was used as external donor. The MFR was 470, which is 220 %
higher than MFR in Comparative Example 3a, where donor D was used. The details and
results are shown in Table 2.
Table 2. The Results of the Comparative Examples
Discussion of results
The difference between the catalyst behaviour used in the examples of the invention and
the typical, supponed Ziegler Natta catalyst used in the comparative examples is best seen
it! Figures 1 and 2. The catalyst used in the examples of the invention show no difference
in hydrogen response independent on whether the external donor is donor C or donor D.
Figure 1. For the typical, supported Ziegler Natta catalyst used in the comparative
examples, donor C gives 100-300 % higher iVIFR than donor D at a certain hydrogen
concentration. Figure 2.
From Table 1 it is also evident that even if the catalyst in this invention shows the same
hydrogen response for donor D and donor C (MFR values are essentially at the same
level), the normal desired differences in polymer properties caused by using different
donors, D and/or C, are maintained as was the target. Donor D gives clearly higher
isotacticity, lower XS, higher Tm and higher stiffness than donor C. The normal differences
caused by using donor D and donor C can be seen also with the typical, supported Ziegler
Natta catalyst used in the comparative experiments and sunmiarized in Table 2. However,
with the comparative catalysts, as can seen in Table 2, there are big variations between
donor C and D in hydrogen response, which is shown by the huge differences between the
MFR results, when the hydrogen feed is kept constant.
WE CLAIM:
1. A process for producing at least two different propylene polymer grades, in which process the
isotacticity of the polymer is changed while keeping the melt flow rate of the polymer at a
predetermined level during a transition of production from a first polymer grade having a
predetermined MFR to a second polymer having the same predetermined MFR, said process being
carried out in a polymerization arrangement comprising at least one polymerization reactor, where
propylene is polymerized, optionally with comonomers, under polymerization conditions in the
presence of hydrogen as a molecular weight controlling agent and a Ziegler-Natta catalyst system,
comprising a catalyst component and a first and a second external donor, respectively, charactc
r i z e d in that the flrst external donor is changed to the second, but the hydrogen feed is kept at a
predetermined level, during a transition of production from the first polymer grade to the second
and wherein the catalyst system comprises a catalyst component prepared according to a liquid-
liquid two phase emulsion method comprising
- preparing a solution of a complex of a Group 2 metal and an electron donor such as herein
described or a precursor thereof in an organic liquid reaction medium,
- reacting said connplex, in solution, with at least one compound of a transition metal to
produce an emulsion, the dispersed phase of which contains more than 50 mol-% of the
Group 2 metal in said complex,
- maintaining the droplets of said dispersed phase within the average size range 5 to 200 (im
by agitation in the presence of an emulsion stabilizer and solidifying said droplets, and
- recovering, washing and drying said particles to obtain said catalyst component
in the form of catalyst particles which exhibit active sites evenly distributed throughout the
particles and wherein the catalyst particles are not supported on any external carrier.
2. The process according to claim 1. wherein the external donors are selected from strongly
coordinating donors.
3. The process according to any of the preceding claims, wherein the external donors are selected
from the group of silane base donors having the general formula
R"\Si(0\Ic),.„ (1)
wherein each R'" is same or different and stands for a branched aliphatic or cyclic or aromatic


group. Me stands for methyl and n is 1 or 2, preferably 2.
4. The process according to any of the preceding claims, wherein the external donors are selected
from the group of dicyclopentyl dimethoxysilane (donor D), cyclohexylmethyl dimethoxy silane
(donor C), diisopropyl dimethoxysilane, methylcyclohexyldimethoxy silane, di-isobutyl
dimethoxysilane, and di-t-butyl dimethoxysilane.
5. The process according to claim 1, wherein the first and the second external donors are the same.
6. The process according to claim 1, wherein the first and the second external donors are different.
7. The process according to any of the preceding claims, wherein the Ziegler-Natta catalyst system
comprises cocatalysts, preferably alkyl aluminium compounds.
8. The process according to any of claims 1 to 7, wherein the hydrogen feed is kept essentially at
the predetermined level during the production of the second polymer grade.
9. The process according to claim 1, wherein the catalyst component is used in the form of particles
having an average size range of 10 to 100, in particular 20 to 50 |um.
10. The process according to claim I, wherein the transition metal is a compound of a Group 4
metal.
11. The process according to claim I. wherein the Group 2 metal is magnesium.
12. The process according to claim 1, wherein said organic liquid reaction medium comprises a ('."(,-
Cio aromatic hydrocarbon or a mixture of C(,-C|., aromatic hydrocarbon and (\- - Co aliphatic
hydrocarbons.
13. The process according to any of the preceding claims, wherein the propylene polymers are
homopolymers. random cijpolv mers. block copolymers or combinalit)ns thereof.
14. The process according lo any of the preceding claims, wherein the hydrogen feed is maintained
within at the most 5 % by volume of a predetermined level during the preparation of the first and


the second polymers.
15. The process according to any of the preceding claims, wherein the hydrogen feed is maintained
within at most 3 % by volume, preferably at most 2 % by volume of a predetermined level during
the preparation of the first and the second polymers.
16. The process according to any of the preceding claims, wherein the polymerization reactor
arrangement comprises at least one reactor selected from liquid (slurry) reactors and gas or vapour
phase reactors.
17. The process according to claim 16, wherein the polymerization reactor arrangement comprises a
cascade of at least two reactors selected from liquid (slurry) reactors and gas or vapour phase
reactor.
18 The process according to claim 16 or 17, wherein the slurry reactor is a bulk reactor, preferably a
loop reactor.
19. The process according to any of the preceding claims, comprising producing a propylene
polymer having a Melt Flow Rate (MFR2) of 0.01 to 1500 g/10 min.
20. The process according to claim 19, comprising producing a propylene polymer having a Melt
Flow Rate (MFR.) of 10 to 300 g/min.
21. The process according to claim 19 or 20. wherein the isotacticity of the propylene polymer is
above 95, in particular above 98.


The invention discloses a process for producing at least two different propylene polymer grades, in
which process the isotacticity of the polymer is changed while keeping the melt flow rate of the
polymer at a predetermined level during a transition of production from a first polymer grade
having a predetermined MFR to a second polymer having the same predetermined MFR, said
process being carried out in a polymerization arrangement comprising at least one polymerization
reactor, where propylene is polymerized, optionally with comonomers, under polymerization
conditions in the presence of hydrogen as a molecular weight controlling agent and a Ziegler-Natta
catalyst system, comprising a catalyst component and a first and a second external donor,
respectively, characterized in that the first external donor is changed to the second, but the
hydrogen feed is kept at a predetermined level, during a transition of production from the first
polymer grade to the second and wherein the catalyst system comprises a catalyst component
prepared according to a liquid-liquid two phase emulsion method.

Documents:

01557-kolnp-2006 assignment.pdf

01557-kolnp-2006 correspondence others-1.1.pdf

01557-kolnp-2006 form-3-1.1.pdf

01557-kolnp-2006-abstract.pdf

01557-kolnp-2006-claims.pdf

01557-kolnp-2006-correspondence others.pdf

01557-kolnp-2006-correspondence-1.2.pdf

01557-kolnp-2006-description complete.pdf

01557-kolnp-2006-drawings.pdf

01557-kolnp-2006-form 1.pdf

01557-kolnp-2006-form 3.pdf

01557-kolnp-2006-form 5.pdf

01557-kolnp-2006-form-18.pdf

01557-kolnp-2006-international publication.pdf

01557-kolnp-2006-international search authority report.pdf

01557-kolnp-2006-pct form .pdf

01557-kolnp-2006-priority document.pdf

1557-KOLNP-2006-CORRESPONDENCE 1.1.pdf

1557-KOLNP-2006-CORRESPONDENCE-(12-12-2011).pdf

1557-KOLNP-2006-FORM 27.pdf

1557-KOLNP-2006-FORM-27.pdf

1557-kolnp-2006-granted-abstract.pdf

1557-kolnp-2006-granted-assignment.pdf

1557-kolnp-2006-granted-claims.pdf

1557-kolnp-2006-granted-correspondence.pdf

1557-kolnp-2006-granted-description (complete).pdf

1557-kolnp-2006-granted-drawings.pdf

1557-kolnp-2006-granted-examination report.pdf

1557-kolnp-2006-granted-form 1.pdf

1557-kolnp-2006-granted-form 18.pdf

1557-kolnp-2006-granted-form 3.pdf

1557-kolnp-2006-granted-form 5.pdf

1557-kolnp-2006-granted-gpa.pdf

1557-kolnp-2006-granted-reply to examination report.pdf

1557-kolnp-2006-granted-specification.pdf

1557-KOLNP-2006-PA-CERTIFIED COPIES-(12-12-2011).pdf

1557-KOLNP-2006-PA.pdf

315-KOLNP-2006-ABSTRACT-1.1.pdf

315-KOLNP-2006-AMENDED PAGES.pdf

315-KOLNP-2006-ANEXURE TO FORM 3.pdf

315-KOLNP-2006-CANCELLED PAGES.pdf

315-KOLNP-2006-CLAIMS-1.1.pdf

315-KOLNP-2006-DESCRIPTION (COMPLETED)-1.1.pdf

315-KOLNP-2006-DRAWINGS-1.1.pdf

315-KOLNP-2006-FORM 1-1.1.pdf

315-KOLNP-2006-OTHERS.pdf

315-KOLNP-2006-PETITION UNDER RULE 137.pdf


Patent Number 236228
Indian Patent Application Number 1557/KOLNP/2006
PG Journal Number 42/2009
Publication Date 16-Oct-2009
Grant Date 12-Oct-2009
Date of Filing 06-Jun-2006
Name of Patentee BOREALLS TECHNOLOGY OY
Applicant Address P.O.BOX 330, FI-06101 PORVOO
Inventors:
# Inventor's Name Inventor's Address
1 VESTBERG, TORVALD VARIKSENMARJANPOLKU 12, FI-06100, PORVOO
PCT International Classification Number C08F 4/44
PCT International Application Number PCT/FI2004/000778
PCT International Filing date 2004-12-17
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 03396115.2 2003-12-19 EUROPEAN UNION