WO2020069853A1

WO2020069853A1 - Method for the manufacture of a polyolefin compound

Info

Publication number: WO2020069853A1
Application number: PCT/EP2019/074859
Authority: WO
Inventors: Robbert Duchateau; Miloud BOUYAHYI; Lidia JASINSKA-WALC
Original assignee: Sabic Global Technologies B.V.
Priority date: 2018-10-02
Filing date: 2019-09-17
Publication date: 2020-04-09

Abstract

The present invention relates to a method for the manufacture of a semi-crystalline polyolefin compound comprising i) a first stage wherein one or more olefinic monomer(s) are reacted in a solvent in the presence of a homogeneous single-site catalyst and a reversible chain transfer agent at a first stage temperature to a first polymer having a first number average molecular weight and a first melting temperature, wherein said first polymer contains said chain transfer agent, ii) a transition stage performed at a transition stage temperature wherein the first polymer crystallises, at least in part, thereby forming a suspension containing said solvent, said single-site catalyst and said olefinic monomer(s) as the liquid phase and crystallised first polymer nano-particles as the solid phase, iii) a second stage wherein one or more olefinic monomers are reacted in said suspension in the presence of said homogeneous single-site catalyst and in absence of reversible chain transfer agent and at a second stage temperature to a second polymer having a second number average molecular weight and a second melting temperature, and wherein said second copolymer crystallises, at least in part, on the crystallised first polymer particles, wherein in said method the first stage temperature and the transition stage temperature are at least 10°C below the crystallisation temperature of the first polymer and the second stage temperature is at most the first stage temperature or the transition stage temperature and at least 10°C below the crystallisation temperature of the second polymer and the molar ratio between the reversible chain transfer agent and the homogeneous single-site catalyst is in the range of from 50 – 10,000.

Description

METHOD FOR THE MANUFACTURE OF A POLYOLEFIN COMPOUND

The present invention relates to a method for the manufacture of a semi-crystalline polyolefin compound wherein one or more olefinic monomer(s) are reacted in a solvent in the presence of a homogeneous single-site catalyst and a reversible chain transfer agent.

The present invention further relates to a semi-crystalline polyolefin compound obtained or obtainable by said method and articles comprising or consisting of such compound. The present invention further relates to a suspension comprising nano-particles, or nano crystals, of semi-crystalline olefin polymers and the use thereof.

Polyolefins are commonly prepared by reacting olefinic monomers in the presence of catalysts. Typical catalysts are for example Ziegler Natta catalysts and single-site catalysts that can homo- and copolymerise olefinic monomers like ethylene, propylene, 1 -butene, 1 -hexene, 1 -octene and the like in high yields, to semi-crystalline and amorphous (co)polymers with high molecular weight and good properties. The present invention relates to a method for the manufacture of a semi-crystalline polyolefin compound.

Olefin polymerisations are usually carried out in slurry or gas phase, wherein the catalysts are supported on a carrier for example to control polymer particle morphology, to achieve a high bulk density and/or to prevent reactor fouling.

Alternatively, the polymerisation can be carried out in solution at a temperature above the crystallisation temperature of the polymer to be produced. At such temperatures a solution is being formed containing the polymer dissolved in the solvent, which is then isolated from the solvent.

Coordinative chain transfer polymerization (CCTP), as for example described in Chem. Rev. 2013, 1 13, 3836-3857, is based on the reversible chain transfer between catalyst and chain transfer agents (CTAs) like magnesium, aluminium or zinc alkyls. When the chain transfer is fast relative to chain growth and b-H transfer is suppressed, a semi living system is created during which multiple polymer chains are growing simultaneously. CCTP is typically performed under solution process conditions above the crystallisation temperature of the polymer, because at a temperature below the crystallisation temperature the reversible chain transfer stops as soon as the molecular weight of the CTA-bonded polymer chains become that high that they crystallise and hence precipitate.

WO 2009/061499 discloses a method of producing a polyolefin composition comprising contacting a metallocene pre-catalyst, a co-catalyst, and a stoichiometric excess of a metal alkyl; adding a first olefin monomer; and polymerising by living coordinative chain transfer said first monomer for a time sufficient to form said polyolefin.

WO 03/014046 discloses a process for the preparation of zinc alkyl chain growth products via a catalysed chain growth reaction of an alpha-olefin on a zinc alkyl, comprising contacting the zinc alkyl with a chain growth catalyst system which employs a group 3-10 transition metal, or a group 3 main group metal, or a lanthanide or actinide complex, and optionally a suitable activator.

US 5,756,609 discloses an olefin homogeneous polymerisation catalyst demonstrating increased activity, which is formed from a cyclopentadienyl metallocene component, a salt of a compatible cation and a non-coordinating anion, and a C₃-C₆ trialkylaluminum, preferably triisobutylaluminium. US 5,756,609 further discloses a homogeneous polymerisation process comprises controlling polymerisation activity with such catalyst by controlling the aluminium/metal (Al/M) molar ratio to a minimal level within the effective range of Al/M ratios.

EP1092730 discloses a process for producing an olefin polymer characterized in that olefin polymerisation or copolymerisation is carried out under the presence of a catalyst comprising (A) a compound of a transition metal selected from among groups 3 to 10 of the periodic table (with lanthanides and actinides being included in group 3) and (B) at least one compound selected from among (B-1 ) organoaluminium oxycompounds, (B-2) compounds that react with the abovementioned compound (A) to form an ion pair, and (B-3) organoaluminium compounds and under the coexistence of (C) an organosilicon compound represented by the general formula R¹ R²R³SiH, or (D) a dialkylzinc compound represented by the general formula ZnR⁴R⁵, wherein R¹ , R² and R³ may be the same or different, with each indicating a hydrogen atom, an alkyl group of 1 to 4 carbon atoms, an aryl group of 6 to 12 carbon atoms, an alkylaryl group of 7 to 20 carbon atoms, an arylalkyl group of 7 to 20 carbon atoms, an alkoxy group of 1 to 4 carbon atoms, a phenoxy group, a fluoroalkyl group of 3 to 6 carbon atoms, a dialkylamino group containing alkyl groups of 1 to 4 carbon atoms, or a diorganopolysiloxane chain containing 1 to 10 siloxane units and wherein R⁴ and R⁵ may be the same or different, with each indicating an alkyl group of 1 to 20 carbon atoms and (E) hydrogen.

A problem in the polymerisation of olefins catalysed by a homogeneous single-site catalyst is fouling of the reactor. Reactor fouling is known and one source of fouling is the actual polymer being formed, which deposits on the internal surfaces of the reactor. Extensive reactor fouling requires the reactors need to be cleaned on a regular basis resulting in down time and loss of production capacity. Reactor fouling is of particular importance for reactions catalysed by homogeneous single-site catalysts which are performed at a temperature below the crystallisation temperature of the polymer that is formed.

Extensive work has been devoted to reduce or eliminate reactor fouling. One technique consists of immobilizing single-site catalysts on a solid support, as described for example in Chem. Rev. 2005, 105 , 4073-4147. Other strategies to reduce such fouling include (a) removing scavengers, used to scavenge poisonous materials like water and other polar agents, before polymerisation starts, or before it is substantially completed, (b) chemically linking the catalyst to a support, or (c) using an ultrasonic process to drive co activator and catalyst into the support.

To avoid reactor fouling caused in particular by static electricity, antifouling/ antistatic agents are being used. A typical example is for example Statsafe™, which contains dodecylbenzenesulfonic acid as active antistatic agent. Other examples are for example polyols, hydroxy-esters and others, such as disclosed in EP 560035. Other examples are given in WO2015/021948.

US2012/0046426 and W02010/132197 disclose the use of magnesium alkyls as anti fouling agent for slurry/gas phase olefin polymerisation using supported single-site catalysts. While these techniques have some effect in slurry and gas phase processes, no solutions have been found for polymerisation of olefin monomers with homogeneous single-site catalysts at temperatures below the crystallisation temperature of the polymer formed in the reaction medium. The reason of the reactor fouling at these temperatures is that the solubility of semi-crystalline polyolefins in most solvents is generally so low that they may crystallise relatively easily. For polymers produced using homogeneous catalysts, the polymer may thus precipitate, which typically occurs on rough and/or cold surfaces such as the stirrer, the reactor walls and the like.

At the same time the polymerisation at temperatures below the crystallisation temperature of the polymer may have advantages including improved catalyst selectivity and/or the possibility to obtain a high(er) molecular weight polymer. In addition to that the formation of a highly viscous reaction medium, which may result in diffusion and heat transfer limitations, is avoided. Despite the advantageous opportunities that single-site catalysts have to offer in respect of activity and selectivity their industrial use, mainly as a result of the reactor fouling, is currently limited to high temperature solution processes and/or processes wherein the catalyst is supported on an inorganic support (like Si0₂, MgC ) allowing them to be used in slurry or gas phase processes.

The present inventors further believe that the problem of reactor fouling may be even worse in case the semi-crystalline polymer to be produced is a functionalised polyolefin, i.e. a polyolefin having functional groups like hydroxyl (-OH) or carbonic acid (-COOFI) groups. In other words, functional polyolefins as used herein are polyolefins having protic groups. Such a functionalised polyolefin is more polar and accordingly likely adheres much stronger to surfaces as compared to otherwise identical yet non-functionalised polyolefins. As a result, in case of reactor fouling, the cleaning of a reactor that is fouled with a functionalised polyolefin may be even more tedious. Thus, the manufacture of functionalised polyolefins at a relatively low temperature is challenging from both an economic and technical perspective.

In view of the foregoing it is an object of the invention to provide for a process for the manufacture of semi-crystalline polyolefins using a homogeneous single-site catalyst and carried out at a temperature below the crystallisation temperature of the polymer formed and wherein the process leads to a reduction in reactor fouling by controlled precipitation of the crystallised polymer product.

Accordingly the invention relates to a method for the manufacture of a semi-crystalline polyolefin compound comprising

i) a first stage wherein one or more olefinic monomer(s) are reacted in a solvent in the presence of a homogeneous single-site catalyst and a reversible chain transfer agent at a first stage temperature to a first polymer having a first number average molecular weight and a first melting temperature, wherein said first polymer contains said reversible chain transfer agent,

ii) a transition stage performed at a transition stage temperature wherein the first polymer crystallises, at least in part, thereby forming a suspension containing said solvent, said single-site catalyst and said olefinic monomer(s) as the liquid phase and crystallised first polymer nano-particles as the solid phase,

iii) a second stage wherein one or more olefinic monomers are reacted in said suspension in the presence of said homogeneous single-site catalyst and in absence of reversible chain transfer agent dissolved in the liquid phase and at a second stage temperature to a second polymer having a second number average molecular weight and a second melting temperature, and wherein said second copolymer crystallises, at least in part, on the crystallised first polymer particles,

wherein in said method,

- the first stage temperature and the transition stage temperature are at least 10 °C below the crystallisation temperature of the first polymer and the second stage temperature is at most the first stage temperature or the transition stage temperature and at least 10 °C below the crystallisation temperature of the second polymer, wherein a crystallisation temperature is determined with DSC using the second heating/cooling curve when operated at a heating rate of 5 °C/min,

- the molar ratio between the homogeneous single-site catalyst and the reversible chain transfer agent is in the range of from 50 - 10,000.

The present inventors found that in such a process reactor fouling can be avoided or at least reduced to a minimum. Without willing to be bound to it, the present inventors believe that the polymer nano-particles generated in the transition stage will act as seed crystals for the polymers that are formed in the second stage. Because the overall surface area that is formed by the polymer nano-particles is several orders of magnitude higher than the surface area of the reactor internals the likelihood of polymers formed in the second stage to deposit (i.e. crystallise) on the reactor internals is reduced significantly if not substantially or completely avoided.

Accordingly under application of the process of the invention the aforementioned object is met.

Without willing to be bound to it, the present inventors believe that the principle underlying the invention is that in the first stage the growing polymer chains transfer continuously and reversibly between the catalyst and the reversible chain transfer agent. Accordingly a reversible chain transfer agent is to be understood as a chain transfer agent that allows a transfer of a growing polymer chain from the catalyst to the chain transfer agent and back from the chain transfer agent to the catalyst. Thus a reversible chain transfer is distinct from a non-reversible chain transfer agent, which only allows chain transfer once. When the growing polymer chain is attached to the catalyst further monomer units are inserted. When the polymer chain is attached to the (reversible) chain transfer agent no insertion is believed to take place. Accordingly in the first stage of the process of the invention the number of polymer chains is proportional to the amount of chain transfer agent that is available in the solution. Depending on the speed of the chain transfer the polymer formed has a relatively small molecular weight distribution while a broader molecular weight distribution is obtained when the chain transfer is relatively slow. At the same time the present inventors also acknowledge that some spontaneous chain termination may take place, for example as a result of some (unavoidable) beta- hydrogen transfer termination. This effect of spontaneous chain termination, in the first stage of the process, is however found to be subordinate to the dominant chain growth mechanism described above. At a certain point in time the polymers have grown to a molecular weight such that the polymers are no longer soluble in the solvent at the reaction temperature. At that point in time the transition stage starts and olefinic polymers start to crystallise from the solution to form nano-particles, or nano-crystals. Because the polymers formed in the first stage are attached to the reversible chain transfer agent, the said reversible chain transfer agent is contained in the said nano-particles so that the availability of reversible chain transfer agent in the solution, where the reaction takes place, reduces. This has the effect that the chain transfer mechanism, wherein growing polymer chains transfer from the reversible chain transfer agent to the catalyst and back again, starts to lose efficiency as well. In other words, during the transition stage the concentration of reversible chain transfer agent dissolved in the liquid phase reduces from the initial concentration in the first stage to substantially zero and the reversible chain transfer mechanism stops or at least becomes insignificant. At that point in time, i.e. where there is substantially no chain transfer agent present in the solution the second stage starts, involving the polymerisation of olefins catalysed by the homogenous single site catalyst in absence of dissolved reversible chain transfer agent. As no reversible chain transfer agents are available anymore the polymer chains will grow on the catalyst until the chain growth is terminated either because no further monomer is available, or because of known chain termination reactions, like the aforementioned beta-hydrogen transfer. Alternatively the reaction is stopped by addition of catalyst deactivators. Alternatively or in addition, hydrogen or any other known (irreversible) chain transfer agent may be used to control the molecular weight and hence to terminate chain growth in this stage. The growing polymer chains in the second stage, as already explained, will crystallise (and may further react) on the nano-particles formed in the transition stage thereby avoiding the deposit of said polymers onto the reactor internals. Accordingly reactor fouling is avoided. The present inventors further found that the staged process as disclosed herein also allows for a controlled morphology where polymer particles are formed having a relatively narrow particle size distribution. Thus, the method according to the present invention allows the polymerisation reaction to start as a homogeneous solution process which transitions into a slurry polymerisation process and allows to reach high molecular weights while effectively reducing or even avoiding reactor fouling by precipitation of crystallised polymer product.

In the first stage no crystallisation takes place and polymers are essentially grown on the reversible chain transfer agent until they reach a molecular weight that no longer allows the chains to be dissolved. This molecular weight depends inter alia on the polymer composition, the solvent and the temperature.

The nano-particles, i.e. nano-crystals, formed in the transition stage have a particle size of a few nanometers less than 500 nm. The present inventors found that a typical size is in the order of from 1 to 400 nm, depending on reaction time and conditions. However most part of the nano-particles size is in the order of from5 to 150 nm . In view of the concept underlying the invention there is no need for the polyolefin constituting the nano-particles to have a specific molecular weight and it is actually preferred that the second number average molecular weight is higher than the first number average molecular weight.

Semi-crystalline polyolefin compound

In the context of the present invention the term“semi-crystalline polyolefin compound” is to be understood as meaning a compound consisting of the polymers that are formed in the method of the invention by reaction of one or more olefinic monomers. Thus, the term “compound” does not include the presence of any separately added materials such as additives, fillers or other polymers.

The term“semi-crystalline” is known to the skilled person per se and refers to a polymer wherein parts of the polymer chains may form crystals. The polymer crystals are generally embedded in an amorphous phase consisting of the non-crystallised parts of the polymer. Thus, semi-crystalline in the sense of the present invention may mean that a semi-crystalline polymer shows a melting endotherm as measured by differential scanning calorimetry (DSC). The semi-crystalline polymer may be determined to be semi-crystalline by differential scanning calorimetry when there is a melting endotherm within the range of 25 ^SC to 400 ^SC, preferably from the range of 25 ^SC to 375 ^SC, more preferably from the range of 25 ^SC to 300 ^SC in the second heating curve at a heating rate of 10 ^sC/min.

The semi-crystalline polyolefin compound consists only of polyolefin materials thus allowing the same to be described using well known parameters in the field of polymer materials, including for example melt flow rate and weight average molecular weight (Mw). The semi-crystalline polyolefin compound consists of the polymers formed during the claimed process and do not contain any materials not formed or used during the method of the invention. Thus, the skilled person will understand that materials used during the method, such as the catalyst and (reversible) chain transfer agent and/or their residues will or may be contained in the compound.

The semi-crystalline polyolefin compound, sometimes referred to herein as the compound, polyolefin compound or semi-crystalline compound, contains two major components, the first being the first polymer obtained in the first and transition stage and the second being the second polymer manufactured in the second stage. The amount of second polymer is generally higher than the amount of first polymer. Accordingly the amount of first polymer in the compound is typically less than 50 wt.%, such as from 0.2 to 20 wt.%, preferably from 0.5 to 10 wt.% and the amount of second polymer from 80 to 98 wt.%, preferably from 90 to 99.5 wt.% on the basis of the total weight of the compound. As explained herein the compound may comprise further polyolefins formed during the first stage, yet the amount of such further polymers is limited and at most 10 wt.%, more preferably at most 5 wt.% or at most 1 wt.% on the basis of the total amount of semi crystalline polyolefin compound.

In an embodiment the invention relates to a method for the manufacture of semi crystalline polyethylene. In another embodiment the invention relates to a method for the manufacture of semi-crystalline polypropylene. In another embodiment the invention relates to a method for the manufacture of a semi-crystalline ethylene copolymer having at least 50 wt.% preferably at least 80 or 90 wt.% ethylene based on the weight of the copolymer. The co-monomer may be propylene, 1 -butene, 1 -hexene, 1 -octene, 4- methyl-1 -pentene (4M1 P), vinyl cyclohexane or functionalised comonomers including 2- propen-1 -ol, 3-buten-1 -ol, 10-undecen-1 -ol, 3-butenoic acid, 4-pentenoic acid, I Q- undecenoic acid. In yet another embodiment the invention relates to a semi-crystalline copolymer of propylene and one or more of the foregoing olefin monomers, wherein said semi crystalline polypropylene has at least 50 wt.% preferably at least 80 or 90 wt.% propylene based on the weight of the copolymer. Non-limiting examples of copolymers are: poly(ethylene-co-propylene), poly(ethylene- co-1 -butene), poly(ethylene-co-propylene-co-1 -butene), poly(ethylene-co-1 -hexene), poly(ethylene-co-l -octene), poly(ethylene-co-4M1 P), poly(ethylene-co-l -octene), poly(ethylene-co-VCH), poly(ethylene-co-2-propen-1 -ol), poly(ethylene-co-3-buten-1 - ol), poly(ethylene-co-10-undecen-1 -ol), poly(ethylene-co-3-butenoic acid), poly(ethylene-co-4-pentenoic acid), poly(ethylene-co-10-undecenoic acid), poly(ethylene-co-propene-co-2-propen-1 -ol), poly(ethylene-co-propene-co-3-buten-1 - ol), poly(ethylene-co-propene-co-10-undecen-1 -ol), poly(ethylene-co-propene-co-3- butenoic acid), poly(ethylene-co-propene-co-4-pentenoic acid), poly(ethylene-co- propene-co-10-undecenoic acid), poly(ethylene-co-1 -hexene-co-2-propen-1 -ol), poly(ethylene-co-1 -hexene-co-3-buten-1 -ol), poly(ethylene-co-1 -hexene-co-10- undecen-1 -ol), poly(ethylene-co-1 -hexene-co-3-butenoic acid), poly(ethylene-co- propene-co-4-pentenoic acid), poly(ethylene-co-1 -hexene-co-10-undecenoic acid), poly(ethylene-co-1 -octene-co-2-propen-1 -ol), poly(ethylene-co-1 -octene-co-3-buten-1 - ol), poly(ethylene-co-1 -octene-co-10-undecen-1 -ol), poly(ethylene-co-1 -octene-co-3- butenoic acid), poly(ethylene-co-1 -octene-co-4-pentenoic acid), poly(ethylene-co-1 - octene-co-10-undecenoic acid), poly(propylene-co-1 -butene), poly(propylene-co-1 - hexene), poly(propylene-co-1 -butene-co-1 -hexene), poly(propylene-co-1 -octene), poly(propylene-co-4M1 P), poly(propylene-co-1 -octene), poly(propylene-co-VCH), poly(propylene-co-2-propen-1 -ol), poly(propylene-co-3-buten-1 -ol), poly(propylene-co-

10-undecen-1 -ol), poly(propylene-co-3-butenoic acid), poly(propylene-co-4-pentenoic acid), poly(propylene-co-10-undecenoic acid), poly(propylene-co-1 -butene-co-2-propen- 1 -ol), poly(propylene-co-1 -butene -co-3-buten-1 -ol), poly(propylene-co-1 -butene-co-10- undecen-1 -ol), poly(propylene-co-1 -butene-co-3-butenoic acid), poly(propylene-co-1 - butene-co-4-pentenoic acid), poly(propylene-co-1 -butene-co-10-undecenoic acid), poly(propylene-co-1 -hexene-co-2-propen-1 -ol), poly(propylene-co-1 -hexene-co-3- buten-1 -ol), poly(propylene-co-1 -hexene-co-10-undecen-1 -ol), poly(propylene-co-1 - hexene-co-3-butenoic acid), poly(propylene-co-1 -hexene-co-4-pentenoic acid), poly(propylene-co-1 -hexene-co-10-undecenoic acid), poly(propylene-co-1 -octene-co-2- propen-1 -ol), poly(propylene-co-1 -octene-co-3-buten-1 -ol), poly(propylene-co-1 -octene- co-10-undecen-1 -ol), poly(propylene-co-1 -octene-co-3-butenoic acid), poly(propylene- co-1 -octene-co-4-pentenoic acid), poly(propylene-co-1 -octene-co-10-undecenoic acid).

The skilled person will understand that if only one olefinic monomer is used for the manufacture of the first and second stage polymers these polymers are homopolymers. Similarly if more than one olefinic monomer is used for the manufacture of the first or second polymer then the first and second polymer will be copolymers. The present invention also includes the possibility for the manufacture of a first polymer being a homopolymer and the second polymer being copolymer or the first polymer being a copolymer and the second polymer being a homopolymer. For the avoidance of doubt and in view of the present invention the term copolymer also includes a polymer that was manufactured by reaction of more than two olefinic monomers. According to the invention, the weight average molecular weight of the semi-crystalline polyolefin compound may be from 10,000 - 5,000,000 g/mol, preferably from 25,000 - 800,000 g/mol, more preferably from 25,000 - 500,000 g/mol, such as from 100,000 - 500,000 g/mol.

The invention relates to the semi-crystalline polyolefin compound obtained or obtainable by the method as disclosed herein. The compound comprises at least 90 wt.% of principle particles having an average diameter of from 0.5 - 10 micrometer as determined using scanning electron microscopy (SEM) wherein the diameter of 100 randomly selected particles in SEM image is measured and then averaged.

The present inventors found that the compound formed in the method contains clusters or agglomerates, with each cluster or agglomerate comprising a number of the principle particles.

The present invention further relates to compositions containing the semi-crystalline compound and at least a further component, preferably selected from one or more of additives like anti-oxidants, UV stabilisers, colorants, pigments, dyes, mold release agents, reinforcing fillers like glass powder, glass flakes, glass fibres, talc, mica, wollastonite, clays, further polymers.

The present invention further relates to articles prepared by melt moulding techniques, such as extrusion moulding, compression moulding, injection moulding, blow moulding, film blowing, calendering and the like and comprising or consisting the semi-crystalline compound obtained or obtainable by the method of the invention.

Olefinic monomers

It is preferred that the olefinic monomer(s) is/are selected from the group consisting of ethylene, propylene, 1 -butene, 1 -hexene, 4-methyl-1 -pentene, 1 -octene, 1 ,5-hexadiene, 3-methyl-1 -butene, vinylcyclohexane, norbornenes, olefinic monomers containing a polar group preferably selected from 3-propen-1 -ol, 4-buten-1 -ol, 1 1 -undecen-1 -ol, 3- butenoic acid, 4-pentenoic acid, 10-undecenoic acid. Norbornenes include norbornene (NB), ethylidene norbornene (ENB), vinyl norbornene (VNB), dicyclopentadiene (DCPD)

The olefinic monomers containing a polar group, also referred to as“functional olefins” may be used to manufacture functionalised polyolefins, i.e. polymers having an olefinic backbone with functional groups incorporated as side groups, in side chains, as end- groups or a combination thereof. Usually functional polyolefins are copolymers of an olefin and an olefin containing a polar group as defined above. Examples of olefinic monomers containing a polar group (functional olefins), are olefins containing electrophilic (e.g. -AIR₂ or -BR₂ groups) and nucleophilic (e.g. -OH, -COOH, -OS1R3, - COOR, -SH, amine groups and their pacified forms (like for example -OAIR₂, - COOAIR₂), wherein R can be hydrocarbyl groups having from 1-40 C atoms, preferably from 1-6 C atoms. Hydrocarbyl as used herein is to be understood as a substituent containing hydrogen and carbon atoms; it may be a linear, branched or cyclic saturated or unsaturated aliphatic substituent, such as alkyl, alkenyl, alkadienyl and alkynyl; alicyclic substituent, such as cycloalkyl, cycloalkadienyl cycloalkenyl; aromatic substituent, such as monocyclic or polycyclic aromatic substituent, as well as combinations thereof, such as alkyl-substituted aryls and aryl-substituted alkyls. It may be substituted with one or more non-hydrocarbyl, heteroatom-containing substituents. It is preferred that the hydrocarbyl groups are alkyl groups.

For example olefinic monomers that may be used, typically as comonomer, are bis(isobutyl)(5-ethylen-yl-2-norbornene) aluminium, di(isobutyl)(7-octen-1 -yl) aluminium, di(isobutyl)(5-hexen-1 -yl) aluminium, di(isobutyl)(3-buten-1 -yl) aluminium.

Functionalised copolymers derived from the copolymerisation of olefins with olefins containing electrophilic functionalities require an additional work-up step to transfer the electrophilic functionality into a nucleophilic functionality. For example, treatment with oxygen or carbon dioxide followed by protonolysis affords hydroxyl and carboxylic acid functionalised copolymers, respectively. For example see: Macromol. Chem. Phys. 2013, 214, 2239-2244.

It is preferred that the olefinic monomers are selected from ethylene and propylene, and olefins containing 4 to 8 carbon atoms. Accordingly it is preferred that the semi-crystalline polymer is a homopolymer or copolymer of any one or more, as the case may be, of these monomers.

Where the present invention is directed at the manufacture of a functionalised polyolefin at least one of the olefinic monomers is selected from 2-propen-1 -ol, 3-buten-1 -ol, 10- undecen-1 -ol, 3-butenoic acid, 4-pentenoic acid, 10-undecenoic acid, bis(isobutyl)(5- ethylen-yl-2-norbornene) aluminium, di(isobutyl)(7-octen-1 -yl) aluminium, di(isobutyl)(5- hexen-1 -yl) aluminium, di(isobutyl)(3-buten-1 -yl) aluminium. The method of the invention is also suitable for the copolymerisation of one or more olefinic monomers as described herein, provided the copolymer remains semi crystalline. Due to their lack of crystallisation temperature the present invention is not directed at a method for the manufacture of amorphous polymers, i.e. polymers that are not semi-crystalline as defined herein.

For example the method of the present invention may be used for the copolymerisation of ethylene and a different olefin monomer such as, but not limited to, for example 1 - butene, 1 -hexene, 1 -octene, 4-methyl-1 -pentene, 1 ,5-hexadiene, vinylcyclohexene, styrene, norbornenes like NB, ENB, VNB, DCPD and olefins containing polar groups to form semi-crystalline olefin (co)polymers such as for example, linear low density polyethylene, ethylene-propylene copolymers, ethylene-propylene-a-olefin terpolymers (e.g. EPR, EPDM, ethylene-propylene-1 -butene terpolymer, ethylene-propylene-1 - hexene terpolymer), propylene-a-olefin copolymers (e.g. propylene-1 -butene copolymers, propylene-1 -hexene copolymers) and copolymers containing polar groups. As used herein, and unless otherwise indicated from the context, "polymerisation" includes copolymerisation.

Reversible Chain Transfer Agent

The reversible chain transfer agent as used in the method of the invention is preferably a zinc-based, magnesium-based, or aluminium based chain transfer agent. Preferably the reversible chain transfer agent is of formula R¹ R²Zn, R¹ R²Mg or R¹ R²R³AI, preferably R¹ R²Zn, and wherein R¹ , R² and R3 are the same or different and selected from a Ci- C4_O alkyl , C1—C40 alkenyl, Ob— C^ aryl or C7— C40 alkylaryl group. Preferably R¹ , R² and R³ are C1 - C12 alkyl groups, preferably methyl, ethyl, n-butyl or isobutyl. Dimethyl zinc or diethyl zinc being preferred reversible chain transfer agents. Preferred aluminium based reversible chain transfer agents are tri-methyl aluminium, tri-ethyl aluminium and tri isobutyl aluminium. Preferred magnesium-based reversible chain transfer agents are dibutyl magnesium and butyl ethyl magnesium.

Examples of such reversible chain transfer agents are those where R¹ , R² and R³ are each, independently, C1-C12 alkyl or alkenyl group. R¹ , R² and R³ may be identical alkyl groups. The alkyl groups may be substituted. Some alkyl groups, for example, may be substituted with an aryl or olefinic group. Particularly preferred reversible chain transfer agents are of formula R¹ R²Zn with dimethyl zinc and diethyl zinc being most preferred.

The present inventors found that if the molar ratio between the reversible chain transfer agent and the homogeneous single-site catalyst is in the range of from 50 - 10,000 then the amount of reactor fouling is reduced to a minimum. The amount of reversible chain transfer agent that is utilised in the reaction depends on the amount of catalyst. The reversible chain transfer agent is soluble in the solvent. A molar concentration of reversible chain transfer agent can be calculated by dividing the molar amount of by the amount of solvent (dm³) used in the polymerisation reactor. The molar ratio of reversible chain transfer agent and catalyst is preferably from 50 - 3,000, more preferably from 75 - 2,000 or from 100 - 1 ,500. For propylene (co)polymerisation, the said molar ratio is preferably from 100-1 ,500, more preferably from 150-500 or 150 - 200. For ethylene (co)polymerisation, the said molar ratio is preferably from 200-3000, more preferably from 500-2000 or from 750-1 ,750.

In the method of the invention a combination, or mixture, of more than one different reversible chain transfer agents may be applied. In the method of the invention the first stage of the method of the invention can be carried out in absence of non-reversible chain transfer agent. In that context a non-reversible chain transfer agent is a chain transfer agent that is not able to transfer a growing polymer chain back to the catalyst. The present invention will also work when such a non-reversible chain transfer agent is present in addition to the reversible chain transfer agent. Catalyst

The term“homogeneous single-site catalyst" refers to a single-site catalyst that is not supported on an (inorganic) support and which dissolves in the reaction medium during the polymerisation reaction. Homogeneous single-site catalysts for the polymerisation of olefinic monomers are known to a skilled person.

As used herein the term“catalyst precursor” means a compound that upon activation forms an active catalyst. The term“catalyst” means a catalyst comprising at least one metal centre that forms the active site. The metal may be a transition metal. Within the same multi-metal centred catalyst, the metal centres may be different. The term“catalyst concentration” refers to the molar amount of catalyst or catalyst precursor in the polymerisation reactor, relative to the amount of solvent used. For the avoidance of doubt it is noted that monomers, cocatalyst, polymer or other ingredients in the polymerisation reactor are not included in the calculation of the catalyst concentration. It is preferred that in the method of the invention the molar concentration of the single-site catalyst is from 0.01 x 10 ⁶ - 20 x 10⁶ mol/L, preferably from 0.01 x 10⁶ - 10 x 10⁶ mol/L, more preferably from 0.05 x 10⁶ - 5 x 10⁶ mol/L.

The term “metallocene" as used herein may for example mean a metal catalyst or catalyst precursor typically consisting of a sandwich complex comprising a transition metal, group 3 metal or lanthanide coordinated to two members of five-member carbon ring, i.e. substituted cyclopentadienyl (Cp), hetero-substituted five- or six-membered aromatic ring, or a bridged (ansa) ligand consisting of five-member carbon rings and/or hetero-substituted five- or six-membered aromatic rings.

The term“half-metallocene" as used herein may for example mean a metal catalyst or catalyst precursor typically consisting of one five-membered carbon ring, i.e. substituted cyclopentadienyl (Cp), hetero-substituted five- or six membered aromatic ring, bound to a metal active site. In particular, preferred half-metallocenes are derivatives of a cyclopentadienyl (Cp) group, including cyclopentadienyl, substituted cyclopentadienyls, indenyl, fluorenyl, tetrahydroindenyl, phosphocyclopentadienes, or borabenzenes. Half metallocene catalysts are typically activated by combining the active metal species with boranes, borates, or aluminoxane compounds well known in the art (for example methylaluminoxane (MAO)), optionally in the presence of alkylating agents like for example trialkyl aluminium compounds.

The term“post-metallocene" as used in the present description and as known to a skilled person may mean especially for example a metal catalyst that contains no substituted cyclopentadienyl (Cp) ligands, but may contain one or more anions bound to the metal active site, typically via a heteroatom. Post-metallocene catalysts are typically activated by combining the active metal species with boranes, borates, or aluminoxane compounds well known in the art (for example methylaluminoxane, MAO), optionally in the presence of alkylating agents like for example trialkyl aluminium compounds.

The transition metal component of the metallocene, half-metallocene or post metallocene catalyst can be selected from Groups NIB through Group VIII of the Periodic Table and mixtures thereof, preferably Group NIB, IVB, VB, VIB, VIII and rare earth (i.e., lanthanides and actinides) metals, and most preferably yttrium, samarium, neodymium, titanium, zirconium, hafnium, vanadium, chromium, iron and nickel. Of these, titanium, hafnium, zirconium, iron and nickel are preferred.

The catalyst used in the process of the present invention is a homogeneous single-site catalyst having one or more transition metals that are able to polymerise olefinic monomers to olefin polymers or copolymers. Preferably, the single-site catalyst is selected from metallocene catalysts, half-metallocene catalysts and post-metallocene catalysts as defined above. The single-site catalyst is generally formed from the reaction between a single-site catalyst precursor and a cocatalyst. Examples of suitable metallocene catalyst precursors are a C₃-, Ci- or C2-symmetric zirconium or hafnium metallocenes, preferably indenyl-substituted zirconium or hafnium dihalides, more preferably bridged bis-indenyl zirconium or hafnium dihalides, even more preferably rac- dimethyl silyl bis-indenyl zirconium or hafnium dichloride (rac-Me₂Si(lnd)2ZrCl2 and rac- Me₂Si(lnd)2HfCl2_, respectively), or rac-dimethylsilyl bis-(2-methyl-4-phenyl-indenyl) zirconium or hafnium dichloride (rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ and rac-Me₂Si(2-Me- 4-Ph-lnd)₂HfCl2, respectively).

Examples of half-metallocene catalyst precursors are 0₅Mb₅[(0₆Hi i )₃R=N]Tί0ΐ₂, [Me₂Si(C₅Me4)N(tBu)]TiCl2, [C₅Me4(CH2CH₂NMe2]TiCl2. Examples of post-metallocenes catalyst precursors are for example [Et₂NC(N(2,6- iPr₂-C6H3)]TiCl3, [N-(2,6-di(1 -methylethyl)phenyl)amido)(2-isopropylphenyl)(a- naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl, bis((2-oxoyl-3- (dibenzo-1 H-pyrrole-1 -yl)-5-(methyl)phenyl)-2-phenoxy)propane-1 ,3-diyl) hafnium dimethyl or [C₅H₃N{CMe=N(2,6-R’₂C₆H₃)}₂]FeCl₂ where R’ is halide or alkyl.

Any homogenous single-site olefin polymerisation catalyst known in the art can be used in the present invention. Also, it is possible to use a combination of more than one different homogeneous single-site catalysts.

Solvent

The solvent is selected such that it allows the polymer to be soluble therein, at least until a certain molecular weight. Preferably the solvent is selected such that polymers having a number average molecular weight up to 5000 g/mol, or at least 50 - 500 g/mol and be can be dissolved without precipitating at the reaction temperature. Accordingly it is preferred that the solvent is selected from the group consisting of hexane, heptane, pentamethylheptane, petroleum ether 60-80, toluene, xylene, isoparaffinic liquids and combinations of one or more of the foregoing.

Additional components

It is preferred that the reaction mixture in one or more of the first stage, transition stage and second stage further contains an aluminium alky compound such as triethyl aluminium, triisobutyl aluminium, trioctyl aluminium and methyl aluminoxane. Such an aluminum compound acts as a scavenger for catalyst deactivating compounds like e.g. oxygen or water. Depending on the catalyst system certain aluminium compounds may thus have a double function. They act as scavenger as well as reversible or irreversible chain transfer agent. Methyl aluminoxane may, as disclosed herein, also act as a co catalyst.

Addition of hydrogen to the reactor may be used to control the molecular weight of the polymer being formed. In particular hydrogen may be used in the second stage. The invention is however also directed at a method wherein no hydrogen is added in any of the stages. In the method of the invention it is also possible to add a non-reversible chain transfer agent. This may be preferred in the second stage of the method.

Process conditions

In the method of the invention it is preferred that the first stage temperature and the transition stage temperature are from 20 - 100°C, preferably from 20 - 90°C and the second stage temperature is at most the first stage temperature or the transition stage temperature. Accordingly, the present invention relates to a method for the manufacture of a semi crystalline polyolefin compound comprising

i) a first stage wherein one or more olefinic monomer(s) are reacted in a solvent in the presence of a homogeneous single-site catalyst and a reversible chain transfer agent at a first stage temperature of from 20 - 100°C, preferably 20 - 90°C to a first polymer having a first number average molecular weight, wherein said first polymer contains said reversible chain transfer agent,

ii) a transition stage performed at a transition stage temperature of from 20 - 100°C, preferably 20 - 90°C, wherein the first polymer crystallises, at least in part, thereby forming a suspension containing said solvent, said single-site catalyst and said olefinic monomer(s) as the liquid phase and crystallised first polymer nano-particles as the solid phase,

iii) a second stage wherein one or more olefinic monomers are reacted in said suspension in the presence of said homogeneous single-site catalyst and in absence of reversible chain transfer agent and at a second stage temperature of at most the transition stage temperature, preferably from 20 - 90°C, to a second polymer having a second number average molecular weight, and wherein said second copolymer crystallises, at least in part, on the crystallised first polymer particles,

wherein in said method,

- the molar ratio between the reversible chain transfer agent and the homogeneous single-site catalyst is in the range of from 50 - 10000

- preferably, the first stage temperature and the transition stage temperature are at least 10°C below the crystallisation temperature of the first polymer and the second stage temperature is at most the first stage temperature or the transition stage temperature and at least 10°C below the crystallisation temperature of the second polymer, wherein a crystallisation temperature is determined with DSC using the second heating/cooling curve when operated at a heating rate of 5°C/min.

All preferred embodiments as disclosed herein also apply to this method.

The temperatures in the three stages of the method of the invention are preferably from 20 °C to 10 °C below the crystallisation temperature of the produced polymer. The crystallisation temperature of the polymer is determined by DSC (second heating/cooling curve, with a heating rate of 5 °C/min). The crystallisation temperature of the polymer produced may be defined as the peak crystallisation temperature as determined by DSC on the second heating/cooling curve with a heating rate of 5 °C/min, as also explained in the experimental section and/or for example further explained in ASTM D3148 and/or in ISO 1 1357-1 :2016 and/or ISO 1 1357-3:201 1 , wherein a scan rate/heating rate of 5 °C/min is applied.

The first stage temperature and the transition stage temperature is at least 10 °C below the crystallisation temperature of the polymer produced, as determined by DSC (second heating/cooling curve, heating rate 5 °C/min). Preferably these temperatures are from 20 °C to said crystallisation temperature minus 10 °C, further preferred minus 20 °C. Thus, if the crystallisation temperature would be 90 °C it is preferred that the first stage and transition stage temperature is at most 80°C, preferably at most 70°C.

The second stage temperature is at most the first stage temperature or the transition stage temperature and at least 10°C, preferably at least 20°C below the crystallisation temperature of the second polymer.

The pressure applied in the method of the invention is not critical and can be from sub- atmospheric to about 200 bar. One preferred pressure range is from atmospheric to about 100 bar, and most preferred from 2 to 50 bar.

Reactors

Reactors for carrying out the method of the invention are known to the skilled person. The method of the invention can be carried out batchwise in one or more reactors or can be carried out in a multiple reactors positioned in series. In a particularly preferred embodiment the method of the invention is a continuous method for the manufacture of a semi-crystalline polyolefin compound. In such a continuous method it is preferred that the method is carried out in at least two reactors in series. In particular it is preferred that the second stage is performed in a reactor separate from the first and/or transition stage. In a variation of this embodiment two or more parallel reactors are connected to a single common reactor transition stage reactor wherein the polymer nano-particles are formed. Such embodiment allows more flexibility and the simultaneous manufacture of different types of semi-crystalline polyolefin compounds. For example, in a first parallel reactor polyethylene compound is manufactured whereas in a second parallel reactor an ethylene - 1 -hexene copolymer compound is manufactured, where both parallel produced compounds are based on the same nano-particles coming a first and transition stage. Notwithstanding the foregoing it is preferred that the monomer composition, i.e. the type of olefinic monomers, in all stages of the method the invention is kept the same. In this way the compatibility of the nano-crystals or nano-particles with the later formed second polymer is guaranteed. The present invention will now be elaborated on the basis of the following examples and Figures 1 -3 which in no way should be interpreted as limiting the scope as defined in the appended claims.

Experimental Section

Materials

All manipulations were performed under an inert dry nitrogen atmosphere using glove box technique. Dry, oxygen-free heptane, pentamethylheptane (PMFI) and hexane were employed as diluents for polymerization experiments. Single-site catalyst rac-Me₂Si(2- Me-4-Ph-lnd)₂ZrCl₂ was purchased from MCAT GmbPI, Konstanz, Germany. Methylaluminoxane (MAO, 30 wt.% solution in toluene) was purchased from Chemtura. Diethyl zinc (DEZ, 1 .0 M solution in hexanes) and triisobutyl aluminum (TiBAI, 1 .0 M solution in hexanes) were purchased from Sigma Aldrich. ¹ H NMR characterization.

Samples were dissolved and analyzed at 130 °C using deuterated trichloroethene (TCE- d₂) solvent and recorded in 5 mm tubes on a Varian Mercury spectrometer operating at a frequency of 400 MHz. Chemical shifts are reported in ppm versus tetramethylsilane and determined by reference to the residual solvent protons.

High Temperature Size Exclusion Chromatography (HT-SEC)

The molecular weights, reported in kg/mol, and the polydispersity index (PDI) were determined by means of high temperature size exclusion chromatography, which was performed at 150 °C in a GPC-IR instrument equipped with an IR4 detector and a carbonyl sensor (PolymerChar, Valencia, Spain). Column set: three Polymer Laboratories 13 pm PLgel Olexis, 300 x 7.5 mm. 1 ,2-Dichlorobenzene (o-DCB) was used as eluent at a flow rate of 1 mL-min-1 . The molecular weights and the corresponding PDIs were calculated from HT SEC analysis with respect to narrow polystyrene standards (PSS, Mainz, Germany).

Differential scanning calorimetry (DSC)

Thermal analysis was carried out on a DSC Q100 from TA Instruments at a heating rate of 5“C-min ¹. First and second runs were recorded after cooling down to ca. -40 °C.

Yield

The yield was determined using the weight of polymer obtained after filtration and drying in vacuum oven overnight at 60 °C.

Examples E1 - E6

Propylene homopolymerisation experiments were carried out in a stainless steel reactor having a volume of 20 L. Conditions of the experiments can be found in Table 1 . The reactor was first washed with PMH (10 L) and TiBAI (20 mL, 1.0 M solution in toluene) and vigorously stirred (500 rpm) for about 120 min at 180 °C. After draining off the washing solvent, PMH was added (15 L) and temperature was set at the desired temperature (80 °C for E1 -E3 and 60 °C for E4-E6) under continuous stirring (300 rpm). Solutions of TiBAI (20 mL, 1 .0 M solution in toluene) and MAO (1 mL, 30 wt. % solution in toluene) were added. The propylene was dosed continuously into the reactor under a stirring speed of 300 rpm until reaching full solvent saturation at the set temperature and 5 bar partial propylene pressure. The indicated amount of DEZ was injected using a 1 .0 M solution in hexanes and applying a 1 bar N₂ overpressure, immediately followed by the injection of the catalyst solution in toluene (in E3 this was 0.5 mg, corresponding to 0.8 pmol rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCI₂ in 15 mL toluene) applying a 1 bar N₂ overpressure. The pressure set point was raised to match the pressure after injecting DEZ and catalyst solutions to keep the partial propylene pressure at 5 bar. After the desired reaction time (e.g. 130 minutes for E3), the mixture was drained via a bottom valve in a dumping vessel (equipped with a filter, particle retention 8 pm) containing acidified isopropanol (2 L, 1 % v/v CH₃COOH,). After cooling down the drained suspension, the filtration was started by opening the valve of dumping vessel. The obtained powder was washed with demineralised water and dried at 60 °C in vacuo overnight (523 g). After cooling, the reactor was opened and the inside is checked for fouling.

Table 1 . Propylene homopolymerisation conducted under homogeneous conditions using rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCI₂ catalyst.³

[a] Conditions: rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ catalyst precursor, C₃ ⁼ monomer 5 bar, pentamethylheptane diluent 15 L, reaction temperature 80 °C, MAO (30 wt.% solution in toluene) AI:Cat ~ 6000.

Examples E7 - E15

Propylene homopolymerisation experiments were carried out in a stainless steel autoclave reactor having a volume of 2 L and equipped with two interMIG stirrer blades, operating at 900 rpm. Conditions of the experiments can be found in Table 2.

The following description applies to E9 illustrating the general procedure for carrying out the polymerisations. PMH (800 ml_) was added to the autoclave using a liquid dosing pump and stirred for 15 minutes. Propylene was dosed via Brooks Mass flow controller into the headspace. The temperature was set at 80 °C. Subsequently, MAO (1 .0 ml_, 30 wt.% solution in toluene) was dosed. After stirring the mixture for 15-20 min at 80 °C, TiBAI (4 ml_, 1 .0 M solution in hexanes) was added followed by DEZ (0.2 ml_, 1 .0 M in hexanes). The mixture was stirred for 10 min and saturated with propylene. The reactor was then heated to 87 °C and the propylene pressure was brought to 9 bar. When the set points were reached, a solution of the catalyst in toluene (1 mg, 1.6 pmol rac- Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ in 4.0 ml_ toluene) was injected into the reactor applying 1 bar over pressure of nitrogen. The pressure set point was raised to match the pressure after injecting the catalyst to keep the partial propylene pressure at 9 bar. After dosing all the components, the total volume of the added PMH was 1 L. The stirring speed was set at 900 rpm and the reactor temperature was kept at 87 ± 3 °C by cooling with an oil LAUDA temperature control system. After 20 minutes, the mixture was drained via a bottom valve in an Erlenmeyer flask containing a mixture of acidified methanol (2.5 % v/v HCI, 1 .0 L) and Irganox 1010. Another 1 L of PMH was then pumped into the reactor and drained into the Erlenmeyer flask. The resulting suspension was stirred for 4 hours and filtered. The wet polymer powder was washed with demineralised water and dried at 60 °C in vacuo overnight (187 g). After cooling, the reactor was opened and the inside is checked for fouling. Table 2. Propylene homopolymerisation conducted under homogeneous conditions using single-site rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ catalyst.³

[a] Conditions: reactions performed in a 2.0 L (E7 - E13) and 0.2 L (E14, 15) steel reactors: rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ catalyst precursor, propylene = 9 bar, solvent = 1 L (E7 - E13), solvent = 0.1 L (E14, E15), Methylaluminoxane (MAO, 30 wt.% solution in toluene) Al:cat. ~ 2800. TiBAI (1 .0 M solution in hexanes) = 4 mmol/L.

Examples E16 - E19

The same procedure as for Examples E7-E15 was applied in ethylene polymerisation conducted using the combination of rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ catalyst/MAO/TiBA/DEZ. The conditions can be found in Table 3. Table 3. Ethylene polymerization conducted under homogeneous conditions using single-site rac-Me₂Si(2-Me-4-Ph-lnd)₂ZrCl₂ catalyst. ^a

[a] Conditions: reactions performed in a 2.0 L steel reactor: rac-Me₂Si(2-Me-4-Ph- lnd)₂ZrCl2 catalyst precursor, ethylene = 9 bar, PMH = 1 L, time = 10 min, methylaluminoxane (MAO, 30 wt.% solution in toluene) Al:cat. ~ 1200.

The fouling of the reactor is shown in Figure 1 . Picture A corresponds to example E1 , picture B corresponds to example E17 and picture C to example E19.

The fouling of the reactor is also shown in Figure 2. Picture A1/A2 corresponds to example E14 while picture B1/B2 corresponds to example E15. Pictures A1 and B1 show the reactor stirrer while pictures A2 and B2 show the reactor internal.

Figure 3A shows the particle morphology of polymer formed in example E15 while Figure 3B shows the same for example E2. The pictures show agglomerates of small principle particles that are relatively uniform in size and shape.

_{* * * * *}

Claims

C L A I M S

1 . Method for the manufacture of a semi-crystalline polyolefin compound having a melting endotherm within the rage of 25 to 400°C in the second heating curve at a heating rate of 10°C/min, comprising i) a first stage wherein one or more olefinic monomer(s) are reacted in a solvent in the presence of a homogeneous single-site catalyst and a reversible chain transfer agent at a first stage temperature from 20 - 100°C to a first polymer having a first number average molecular weight and a first melting temperature, wherein said first polymer contains said chain transfer agent, ii) a transition stage performed at a transition stage temperature of from 20 - 100°C, wherein the first polymer crystallises, at least in part, thereby forming a suspension containing said solvent, said single-site catalyst and said olefinic monomer(s) as the liquid phase and crystallised first polymer nano-particles as the solid phase, wherein the nano-particles formed have a particle size from 1 to 400 nm, iii) a second stage wherein one or more olefinic monomers are reacted in said suspension in the presence of said homogeneous single-site catalyst and in absence of reversible chain transfer agent dissolved in the liquid phase and at a second stage temperature, from 20 - 100°C, preferably from 20 - 90°C to a second polymer having a second number average molecular weight and a second melting temperature, and wherein said second copolymer crystallises, at least in part, on the crystallised first polymer particles, wherein in said method,

- the first stage temperature and the transition stage temperature are at least 10°C below the crystallisation temperature of the first polymer and the second stage temperature is at most the first stage temperature or the transition stage temperature and at least 10°C below the crystallisation temperature of the second polymer, wherein a crystallisation temperature is determined with DSC using the second heating/cooling curve when operated at a heating rate of 5°C/min, - the molar ratio between the reversible chain transfer agent and the homogeneous single-site catalyst is in the range of from 50 - 10,000.

2. The method of claim 1 wherein the compound is manufactured in a single reactor or in one or more reactors in series.

3. The method of claim 1 or 2 wherein the first stage temperature and the transition stage temperature are from 20 - 100°C, preferably from 20 - 90°C and the second stage temperature is at most the first stage temperature or the transition stage temperature.

4. The method of any one or more of claims 1 -3 wherein the reversible chain transfer agent is a zinc-based, magnesium-based, or aluminium based chain transfer agent, preferably of formula R¹ R²Zn or R¹ R²Mg, preferably R¹ R²Zn, and wherein R¹ and R² are the same or different and selected from a C1-C40 alkyl, C1-C40 alkenyl, C₆-C₄₀ aryl or C₇-C₄₀ alkylaryl group, the reversible chain transfer agent preferably being dimethyl zinc or diethyl zinc.

5. The method of any one or more of claims 1 -4 wherein the second number average molecular weight is higher than the first number average molecular weight,

6. The method of any one or more of claims 1 -5 wherein the olefinic monomers are selected from the group consisting of ethylene, propylene, 1 -butene, 1 -hexene, 4- methyl-1 -pentene, 1 -octene, 1 ,5-hexadiene, 3-methyl-1 -butene, vinylcyclohexane, styrene, norbornenes, olefinic monomers containing a polar group preferably selected from 3-propen-1 -ol, 4-buten-1 -ol, 1 1 -undecen-1 -ol, 3-butenoic acid, 4- pentenoic acid, 10-undecenoic acid .

7. The method of any one or more of claims 1 -6 wherein the solvent is selected from the group consisting of hexane, heptane, pentamethylheptane, petroleum ether 60- 80, toluene, xylene, isoparaffinic liquids and combinations of one or more of the foregoing, preferably selected from the group consisting of hexane, heptane, pentamethylheptane, petroleum ether 60-80, isoparaffinic liquids and combinations of one or more of the foregoing.

8. The method of any one or more of claims 1 -7 wherein the olefinic monomer(s) in the first and second stage is/are the same.

9. The method of any one or more of claims 1 -8 wherein the weight average molecular weight of the semi-crystalline polyolefin compound is from 25,000 - 5,000,000 g/mol, preferably from 25,000 - 800,000 g/mol, more preferably from 25,000 - 500,000 g/mol, such as from 100,000 - 500,000 g/mol.

10. The method of any one or more of claims 1 -9 wherein the compound comprises at most 50 wt.% of first polymer, preferably from 0.5 to 10 wt.% based on weight of the compound.

1 1 . A semi-crystalline polyolefin compound having a melting endotherm within the rage of 25 to 400°C in the second heating curve at a heating rate of 10°C/min, obtained or obtainable by the method of any one or more of claims 1 -10.

12. The semi-crystalline polyolefin compound of claim 1 1 , said compound comprising at least 90 wt.% of principle particles, based on the total weight of the particles, having an average diameter of from 0.5 - 10 micrometer as determined by scanning electron microscopy wherein a diameter is measured on 100 randomly selected principle particles.

13. An article comprising or consisting of the semi-crystalline polyolefin compound of claims 1 1 or 12.

14. Use of olefinic polymer nano-particles in the range of 1 to 400 nm, suspended in a solvent as seed crystals for crystallising olefinic polymers resulting from a reaction in said solvent between olefinic monomers in the presence of a homogeneous single site catalyst and preferably in absence of chain transfer agent.

15. A thermoplastic composition comprising the semi-crystalline polyolefin of claim 1 1 or 12 and at least one further component.