Patent Description:
Polystyrene is one of the widely used polymers in the daily life, including packaging, due to its excellent combination of high stiffness, high transparency and low costs. However polystyrene has the disadvantage that its monomer is a problem under environmental, health and safety aspects and recycling requires a highly pure feedstock and thus other polymers not having such disadvantages are preferred. One of such polymers is polypropylene.

Polypropylene is one of the best choices, as it is rather cheap has good stiffness and can be widely used without environmental, health and safety concerns. However, even though its stiffness is already quite good it is still not comparable to the stiffness of polystyrene. Also, the optics of typical polypropylene need further improved to be competitive with polystyrene. It is known that propylene homopolymer produced with metallocene catalysts has improved behavior regarding the required properties for the use in injection molded articles compared to known propylene homopolymer produced with Ziegler-Natta catalysts. However, such a metallocene propylene homopolymer is still not competitive enough in view of polystyrene.

Thus, the object of the present invention is to provide a polypropylene having enhanced stiffness and optical properties compared to polypropylenes already being state of the art.

The finding of the present invention is to provide a polypropylene being bimodal in molecular weight distribution and having a low comonomer content, i.e. not exceeding <NUM> mol-%, wherein said bimodal polypropylene is alpha-nucleated.

Hence, the present invention is directed to an alpha-nucleated polypropylene composition (n-PP) comprising.

wherein further the alpha-nucleated polypropylene composition (n-PP) has.

Preferably the alpha-nucleated polypropylene composition (n-PP) contains at least one alpha-nucleating agent selected from the group consisting of polymeric nucleating agent, sorbitol-based nucleating agent, nonitol-based nucleating agent and benzene-trisamide-based nucleating agent. Still more preferably the alpha-nucleating agent is selected from the group consisting of <NUM>,<NUM>,<NUM>-trideoxy-<NUM>,<NUM>;<NUM>,<NUM>-bis-O-[(<NUM>-propylphenyl)methylene] nonitol, bis-(<NUM>,<NUM>-dimethylbenzylidene)-sorbitol (DMDBS) and poly vinylcyclohexane (p-VCH). Yet more preferably the alpha-nucleating agent(s) present in the alpha-nucleated polypropylene composition (n-PP) is/are selected from the group consisting of <NUM>,<NUM>,<NUM>-trideoxy-<NUM>,<NUM>;<NUM>,<NUM>-bis-O-[(<NUM>-propylphenyl)methylene] nonitol, bis-(<NUM>,<NUM>-dimethylbenzylidene)-sorbitol (DMDBS) and poly vinylcyclohexane (p-VCH).

Preferably the total amount of alpha-nucleating agent within the alpha-nucleated polypropylene composition (n-PP) is in the range of <NUM> to <NUM> wt. Thus, it is especially preferred that the alpha-nucleating agent(s) present in the alpha-nucleated polypropylene composition (n-PP) is/are selected from the group consisting of poly vinylcyclohexane (p-VCH), <NUM> ,<NUM>,<NUM>-trideoxy-<NUM>,<NUM>;<NUM>,<NUM>-bis-O-[(<NUM>-propylphenyl)methylene] nonitol and bis-(<NUM>,<NUM>-dimethylbenzylidene)-sorbitol (DMDBS), wherein further the total amount of the alpha-nucleating agent(s), based on the total amount of the alpha-nucleated polypropylene composition (n-PP), is in the range of <NUM> to <NUM> wt.

Further preferred embodiments of the alpha-nucleated polypropylene composition (n-PP) according to this invention are defined in the claims.

Additionally, the present invention is also directed to an injection molded article, more preferably to an thin wall injection molded article, consisting of the alpha-nucleated polypropylene composition (n-PP) according to this invention, wherein preferably the thin wall injection molded article has a wall thickness up to <NUM>.

In the following, the invention is described in more detail.

The alpha-nucleated polypropylene composition (n-PP) according to this invention comprises two different polypropylenes (PP1) and (PP2) and additionally an alpha nucleating agent. The main components of the alpha-nucleated polypropylene composition (n-PP) are the two different polypropylenes (PP1) and (PP2). In other words the total amount of the two different polypropylenes (PP1) and (PP2), based on the alpha-nucleated polypropylene composition (n-PP), is at least <NUM> wt. -%, more preferably at least <NUM> wt.

The remaining part of the alpha-nucleated polypropylene composition (n-PP) is the alpha-nucleating agent, further optional polypropylene(s) as defined further below and optionally typical additives, like antioxidants, antistatic agents and antifogging agents.

The amount of alpha-nucleating agent, based on the total alpha-nucleated polypropylene composition (n-PP), is preferably in the range of <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. -%, still more preferably in the range of <NUM> to <NUM> wt. -%, yet more preferably in the range of <NUM> to <NUM> wt.

Typically the total amount of additives, excluding the alpha-nucleating agent, based on the total alpha-nucleated polypropylene composition (n-PP), shall not exceed <NUM> wt. -%, preferably is in the range of <NUM> to <NUM> wt.

The alpha-nucleating agent and the additives may be added to the polypropylene comprising the polypropylenes (PP1) and (PP2) together with low amounts of polyolefins being different to the polypropylenes (PP1) and (PP2). The term "different to" in this context means that the polyolefin differs from the polypropylenes (PP1) and (PP2) in at least one typical characterizing feature in the field of polymers, like molecular weight, for instance in terms of melt flow rate MFR<NUM> (<NUM>; <NUM>), melting point and/or misinsertions, for instance in <NUM>,<NUM> erythro regio-defects. Preferably the polyolefins used for this purpose are polypropylenes, especially a propylene homopolymer. Accordingly, such polypropylene, more preferably such propylene homopolymer, has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>. Even more preferably, such polypropylene, still more preferably such propylene homopolymer, has been produced with a Ziegler-Natta catalyst of the <NUM>th or <NUM>th generation (cf. pages17/<NUM> of "Polypropylene Handbook" <NUM>nd Edition of Nello Pasquini) and thus has a highest melting peak temperature Tp,m measured by DSC (scan rate of <NUM>/min; second heating step) in the range of <NUM> to <NUM>. A typical additional feature of such a polypropylene, more preferably of such a propylene homopolymer, produced with a Ziegler-Natta catalyst of the <NUM>th or <NUM>th generation is that it does not show <NUM>,<NUM> erythro regio-defects, i.e. has no detectable <NUM>,<NUM> erythro regio-defects when analyzed according to this invention. Accordingly it is preferred that the alpha-nucleated polypropylene composition (n-PP) comprise one or more propylene homopolymer(s) being different to the polypropylenes (PP1) and (PP2), wherein said one or more propylene homopolymer(s), has/have a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>. More preferably, the one or more propylene homopolymer(s) being different to the polypropylenes (PP1) and (PP2) has/have a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM> and a highest melting peak temperature Tp,m measured by DSC (scan rate of <NUM>/min; second heating step) in the range of <NUM> to <NUM>. Even more preferred the one or more propylene homopolymer(s) being different to the polypropylenes (PP1) and (PP2), has/have a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, a highest melting peak temperature Tp,m measured by DSC (scan rate of <NUM>/min; second heating step) in the range of <NUM> to <NUM> and no detectable <NUM>,<NUM> erythro regio-defects measured by <NUM>C NMR. The total amount of the one or more propylene homopolymer(s) as defined in this paragraph , based on the total amount of the alpha-nucleated polypropylene composition (n-PP), is in the range of <NUM> to <NUM> wt.

Accordingly the present invention is especially directed to an alpha-nucleated polypropylene composition (n-PP) comprising, preferably consisting of,.

wherein further the alpha nucleated polypropylene composition (n-PP) has.

Preferably, the alpha-nucleated polypropylene composition (n-PP) as defined in the previous paragraph is an alpha-nucleated propylene homopolymer or an alpha-nucleated propylene-<NUM>-butene copolymer having a <NUM>-butene content in the range of <NUM> to <NUM> mol-%, more preferably the alpha-nucleated polypropylene composition (n-PP) as defined in the previous paragraph is an alpha-nucleated propylene homopolymer.

The alpha-nucleated polypropylene composition (n-PP) is dominated by the first polypropylene (PP1) and the second polypropylene (PP2), as both polymers make up at least <NUM> wt. -% of the alpha-nucleated polypropylene composition (n-PP). As will be explained below, the first polypropylene (PP1) and the second polypropylene (PP2) are produced together in a sequential polymerization process using a specific metallocene catalyst. The first polypropylene (PP1) is produced in the <NUM>st reactor and subsequently in a second reactor and in the presence of first polypropylene (PP1) the second polypropylene (PP2) is produced. Accordingly as the alpha-nucleated polypropylene composition (n-PP) has as main component the polymerization product of the first polypropylene (PP1) and the second polypropylene (PP2) (at least <NUM> wt. -%), at least some of final properties are also driven by said two polypropylenes (PP1) and (PP2).

Therefore, as both polypropylenes (PP1) and (PP2) are produced in the presence of a specific metallocene catalyst, the final alpha-nucleated polypropylene composition (n-PP) has a certain amount of <NUM>,<NUM> erythro regio-defects, preferably also a rather low xylene soluble content and a rather high crystallinity in terms of pentad isotacticity [mmmm].

Accordingly, the alpha-nucleated polypropylene composition (n-PP) has <NUM>,<NUM> erythro regio-defects measured by <NUM>C NMR in the range of ><NUM> to <NUM> mol-%, preferably in the range of <NUM> to <NUM> mol-%.

Further, it is preferred that the alpha-nucleated polypropylene composition (n-PP) has a pentad isotacticity [mmmm] of at least <NUM> %, more preferably of at least <NUM> %, yet more preferably of at least <NUM> %.

Additionally or alternatively to the previous paragraph it is preferred that the alpha-nucleated polypropylene composition (n-PP) has a xylene cold soluble fraction (XCS) measured at <NUM> according to ISO <NUM> of not more than <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. -%, still more preferably in the range of <NUM> to <NUM> wt.

Accordingly, the present invention is in particular directed to an alpha-nucleated polypropylene composition (n-PP) comprising, preferably consisting of,.

The polypropylenes (PP1) and (PP2) differ essentially in the melt flow rate otherwise the rather broad molecular weight distribution (MWD) of the alpha-nucleated polypropylene composition (n-PP) in the range of <NUM> to <NUM> would be not possible. It is even more preferred that the molecular weight distribution (MWD) of the alpha-nucleated polypropylene composition (n-PP) is in the range of <NUM> to <NUM>. A further consequence of the fact that the polypropylenes (PP1) and (PP2) differ essentially in the melt flow rates is that also the melt flow rate MFR<NUM> of the alpha-nucleated polypropylene composition (n-PP) is essentially higher than the melt flow rate MFR<NUM> of the first polypropylene (PP1). Hence, it is preferred that the alpha-nucleated polypropylene composition (n-PP) complies with.

Accordingly, the present invention is in particular directed to an alpha-nucleated polypropylene composition (n-PP) comprising.

As mentioned above, the alpha-nucleated polypropylene composition (n-PP) essentially consists of the first polypropylene (PP1) and the second polypropylene (PP2). Further, the comonomer content of the alpha-nucleated polypropylene composition (n-PP) is not more than <NUM> mol-%. Thus, the highest amount of comonomer in one of the two polypropylenes (PP1) and (PP2) can be <NUM> mol-% assuming the other is a propylene homopolymer. Actually, it is the second polypropylene (PP2) which only can have such an high amount. However, a content of <NUM> mol-% of comonomer means that the polypropylene is still crystalline. In other words, the alpha-nucleated polypropylene composition (n-PP) mainly contains two crystalline polypropylenes. Therefore, the alpha-nucleated polypropylene composition (n-PP) contains two polypropylenes which are miscible. Thus, it is preferred that the alpha-nucleated polypropylene composition (n-PP) is monophasic. In other words, the α-nucleated polypropylene composition (n-PP) does not comprise polymer components which are not miscible with each other, as this is the case for heterophasic propylene copolymers. In contrast to monophasic systems, heterophasic systems comprise a continuous polymer phase, like a polypropylene, in which a further non-miscible polymer, like an elastomeric polymer, is dispersed as inclusions. Said polypropylene systems containing a polypropylene matrix and inclusions as a second polymer phase would by contrast be called heterophasic and are not part of the present invention. The presence of second polymer phases or the so-called inclusions is for instance visible by high resolution microscopy, like electron microscopy or atomic force microscopy, or by dynamic mechanical thermal analysis (DMTA). Specifically in DMTA, the presence of a multiphase structure can be identified by the presence of at least two distinct glass transition temperatures.

Accordingly, the present invention is in particular directed to an alpha-nucleated monophasic polypropylene composition (n-PP) comprising.

The alpha-nucleated polypropylene composition (n-PP) according to this invention can be defined further by its melting and crystallization behavior. The alpha-nucleated polypropylene composition (n-PP) according to this invention is characterized in particular by a relatively small gap between melting and crystallization temperature. For defining the melting and crystallization temperature always the highest melting peak temperature Tp,m measured by DSC (scan rate of <NUM>/min; second heating step) and the highest crystallization peak temperature Tp,c measured by DSC (scan rate of <NUM>/min; cooling step) is used. Thereby it is especially preferred that the alpha-nucleated polypropylene composition (n-PP) has a highest melting peak temperature Tp,m which is rather high for metallocene produced polypropylenes. Accordingly, it is preferred that the alpha-nucleated polypropylene composition (n-PP) according to this invention has.

Thus, the invention is especially directed to an alpha-nucleated polypropylene composition (n-PP) comprising.

Preferably, the alpha-nucleated polypropylene composition (n-PP) as defined in the previous paragraph is monophasic, even more preferably the alpha-nucleated polypropylene composition (n-PP) as defined in the previous paragraph is monophasic and is an alpha-nucleated propylene homopolymer or an alpha-nucleated propylene-<NUM>-butene copolymer having a <NUM>-butene content in the range of <NUM> to <NUM> mol-%, most preferably the alpha-nucleated polypropylene composition (n-PP) as defined in the previous paragraph is monophasic and is an alpha-nucleated propylene homopolymer.

The alpha-nucleated polypropylene composition (n-PP) according to this invention can be defined further by its high stiffness and low haze.

Accordingly it is preferred that the alpha-nucleated polypropylene composition (n-PP) has a flexural modulus measured according to ISO <NUM> on injection molded specimens in the range of <NUM> to <NUM> MPa and/or a haze measured according to ASTM D1003-<NUM> on injection molded plaques of <NUM> thickness of below <NUM> %, more preferably in the range of <NUM> to below <NUM> %. Thus, all the previously defined embodiments additionaly have a flexural modulus measured according to ISO <NUM> on injection molded specimens in the range of <NUM> to <NUM> MPa and optionally a haze measured according to ASTM D1003-<NUM> on injection molded plaques of <NUM> thickness of below <NUM> %, more preferably in the range of <NUM> to below <NUM> %.

As mentioned above the first polypropylene (PP1) and the second polypropylene (PP2) of the alpha-nucleated polypropylene composition (n-PP) are produced in a sequential polymerization process using a specific metallocene catalyst. Accordingly, the first polypropylene (PP1) and the second polypropylene (PP2) of the alpha-nucleated polypropylene composition (n-PP) must be produced with a metallocene catalyst as disclosed in <CIT>, which is incorporated by reference herewith.

The used metallocene catalyst complexes for the manufacture of the first polypropylene (PP1) and the second polypropylene (PP2) of the alpha-nucleated polypropylene composition (n-PP) is in particular defined by formula (I):
<CHM>.

In a complex of formula (I) it is preferred if Mt is Zr or Hf, preferably Zr; each X is a sigma ligand. Most preferably, each X is independently a hydrogen atom, a halogen atom, C<NUM>-C<NUM> alkoxy group or an R' group, where R' is a C<NUM>-C<NUM> alkyl, phenyl or benzyl group. Most preferably, X is chlorine, benzyl or a methyl group. Preferably, both X groups are the same. The most preferred options are two chlorides, two methyl or two benzyl groups, especially two chlorides. For further preferred defintions of the residues reference is made to <CIT>.

Specifically preferred metallocene catalyst complexes are:.

The corresponding zirconium dimethyl analogues of the above defined three catalysts are also possible but less preferred. The most preferred catalyst is the one used for the inventive examples, i.e. MC-<NUM>.

To form an active catalytic species it is normally necessary to employ a cocatalyst as is well known in the art. Here, a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst is used in combination with the above defined metallocene catalyst complex.

Typical aluminoxane cocatalysts are state of the art. The preferred aluminoxane is methylaluminoxane (MAO). Since the aluminoxanes used according to the invention as cocatalysts are not, owing to their mode of preparation, pure compounds, the molarity of aluminoxane solutions hereinafter is based on their aluminium content.

As mentioned above the aluminoxane cocatalyst is used in combination with a boron containing cocatalyst.

Boron based cocatalysts of interest include those of formula (Z).

wherein Y is the same or different and is a hydrogen atom, an alkyl group of from <NUM> to about <NUM> carbon atoms, an aryl group of from <NUM> to about <NUM> carbon atoms, alkylaryl, arylalkyl, haloalkyl or haloaryl each having from <NUM> to <NUM> carbon atoms in the alkyl radical and from <NUM>-<NUM> carbon atoms in the aryl radical or fluorine, chlorine, bromine or iodine. Preferred examples for Y are methyl, propyl, isopropyl, isobutyl or trifluoromethyl, unsaturated groups such as aryl or haloaryl like phenyl, tolyl, benzyl groups, p-fluorophenyl, <NUM>,<NUM>-difluorophenyl, pentachlorophenyl, pentafluorophenyl, <NUM>,<NUM>,<NUM>-trifluorophenyl and <NUM>,<NUM>-di(trifluoromethyl)phenyl. Preferred options are trifluoroborane, triphenylborane, tris(<NUM>-fluorophenyl)borane, tris(<NUM>,<NUM>-difluorophenyl)borane, tris(<NUM>-fluoromethylphenyl)borane, tris(<NUM>,<NUM>,<NUM>-trifluorophenyl)borane, tris(penta-fluorophenyl)borane, tris(tolyl)borane, tris(<NUM>,<NUM>-dimethyl-phenyl)borane, tris(<NUM>,<NUM>-difluorophenyl)borane and/or tris (<NUM>,<NUM>,<NUM>-trifluorophenyl)borane. Particular preference is given to tris(pentafluorophenyl)borane.

Preferred ionic compounds which can be used include:.

Preference is given to triphenylcarbeniumtetrakis(pentafluorophenyl) borate, N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate or N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate. Certain boron cocatalysts are especially preferred. Preferred borates comprise the trityl ion. Thus, the use of N,N-dimethylammonium-tetrakispentafluorophenylborate and Ph<NUM>CB(PhF<NUM>)<NUM> and analogues therefore are especially favoured.

It is especially preferred the combination of a borate cocatalyst, like Trityl tetrakis(pentafluorophenyl) borate, and methylaluminoxane (MAO).

Suitable amounts of cocatalyst will be well known to the skilled man.

The molar ratio of boron to the metal ion of the metallocene may be in the range of <NUM>:<NUM> to <NUM>:<NUM> mol/mol, preferably in the range of <NUM>:<NUM> to <NUM>:<NUM>, especially in the range of <NUM>:<NUM> to <NUM>:<NUM> mol/mol.

The molar ratio of Al in the aluminoxane to the metal ion of the metallocene may be in the range of <NUM>:<NUM> to <NUM>:<NUM> mol/mol, preferably in the range of <NUM>:<NUM> to <NUM>:<NUM>, and more preferably in the range of <NUM>:<NUM> to <NUM>:<NUM> mol/mol.

The metallocene catalyst complex can be used in combination with a suitable cocatalyst as a catalyst for the polymerization of propylene, e.g. in a solvent such as toluene or an aliphatic hydrocarbon, (i.e. for polymerization in solution), as it is well known in the art. Preferably, polymerization of propylene takes place in the condensed phase or in gas phase.

The catalyst of the invention can be used in supported or unsupported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina or zirconia or a mixed oxide such as silica-alumina, in particular silica, alumina or silica-alumina. The use of a silica support is preferred. The skilled man is aware of the procedures required to support a metallocene catalyst.

Especially preferably the support is a porous material so that the complex may be loaded into the pores of the support, e.g. using a process analogous to those described in <CIT>, <CIT> and <CIT>. The particle size is not critical but is preferably in the range of <NUM> to <NUM> pm, more preferably in the range of <NUM> to <NUM> pm. The use of these supports is routine in the art.

Alternatively, no support is used at all. Such a catalyst can be prepared in solution, for example in an aromatic solvent like toluene, by contacting the metallocene (as a solid or as a solution) with the cocatalyst, for example methylaluminoxane or a borane or a borate salt previously dissolved in an aromatic solvent, or can be prepared by sequentially adding the dissolved catalyst components to the polymerization medium.

Also, no external carrier may be used but the catalyst is still presented in solid particulate form. Thus, no external support material, such as inert organic or inorganic carrier, for example silica as described above is employed.

In order to provide the catalyst in solid form but without using an external carrier, it is preferred if a liquid/liquid emulsion system is used. Full disclosure of the necessary process can be found in <CIT>, which is herein incorporated by reference.

The most preferred catalyst system is defined in the example section below (single site catalyst system <NUM> (SSCS1)).

The polymerization conditions in the sequential polymerization of the first polypropylene (PP1) and the second polypropylene (PP2) of the alpha-nucleated polypropylene composition (n-PP) are nothing specific and well known to the skilled person. Typically the first polypropylene (PP1) is produced in a slurry reactor and the second polypropylene (PP2) is produced in a gas phase reactor in the presence of a the first polypropylene (PP1). Regarding such multistage processes a preferred process is a "loop-gas phase"-process, such as developed by Borealis A/S, Denmark (known as BORSTAR® technology) described e.g. in patent literature, such as in <CIT>, <CIT> <CIT>,.

<CIT>, <CIT>, <CIT>, <CIT>, <CIT> or in <CIT>.

It is well known that prior to the main polymerization a prepolymerization may take place.

The prepolymerisation may be carried out in any type of continuously operating polymerization reactor. The prepolymerisation may be carried out in a slurry polymerization or a gas phase polymerization reactor, preferably in a loop prepolymerisation reactor.

In a preferred embodiment, the prepolymerisation is conducted as bulk slurry polymerization in liquid propylene, i.e. the liquid phase mainly comprises propylene, with minor amount of other reactants and optionally inert components dissolved therein.

The prepolymerisation is carried out in a continuously operating reactor at an average residence time of <NUM> minutes up to <NUM>. Preferably the average residence time is within the range of <NUM> to <NUM> minutes and more preferably within the range of <NUM> to <NUM> minutes.

The prepolymerisation reaction is typically conducted at a temperature of <NUM> to <NUM>, preferably from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>.

The pressure in the prepolymerisation reactor is not critical but must be sufficiently high to maintain the reaction mixture in liquid phase and is generally selected such that the pressure is higher than or equal to the pressure in the subsequent polymerization. Thus, the pressure may be from <NUM> to <NUM> bar, for example <NUM> to <NUM> bar.

In case a prepolymerisation step is performed, all of the catalyst mixture is introduced to the prepolymerisation step.

The precise control of the prepolymerisation conditions and reaction parameters is within the skill of the art.

As mentioned above the first polypropylene (PP1) is preferably produced in a slurry phase polymerization step, i.e. in the liquid phase.

The temperature in the slurry polymerization is typically from <NUM> to <NUM>, preferably from <NUM> to <NUM> and in particular from <NUM> to <NUM>. The pressure is from <NUM> to <NUM> bar, preferably from <NUM> to <NUM> bar.

The slurry polymerization may be conducted in any known reactor used for slurry polymerization. Such reactors include a continuous stirred tank reactor and a loop reactor. It is especially preferred to conduct the polymerization in loop reactor. Loop reactors are generally known in the art and examples are given, for instance, in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

The residence time can vary in the reactor zones identified above. In one embodiment, the residence time in the slurry reactor, for example a loop reactor, is in the range of from <NUM> to <NUM> hours, for example <NUM> to <NUM> hours, while the residence time in the gas phase reactor generally will be in the range from <NUM> to <NUM> hours, like from <NUM> to <NUM> hours.

Into the slurry polymerization stage other components may also be introduced as it is known in the art. Thus, hydrogen is added to control the molecular weight of the polymer.

The slurry polymerization stage is followed by the gas phase polymerization stage in which the second polypropylene (PP2) is produced. It is preferred to conduct the slurry directly into the gas phase polymerization zone without a flash step between the stages. This kind of direct feed is described in <CIT>, <CIT>, <CIT> and <CIT>.

That is, the reaction product of the slurry phase polymerization, i.e. the first polypropylene (PP1), which preferably is carried out in a loop reactor, is then transferred to the subsequent gas phase reactor in which the second polypropylene (PP2) is produced.

The polymerization in gas phase may be conducted in fluidized bed reactors, in fast fluidized bed reactors or in settled bed reactors or in any combination of these. When a combination of reactors is used then the polymer is transferred from one polymerization reactor to another. However it is preferred that the second polypropylene (PP2) is produced in one gas phase reactor.

Typically the gas phase reactor is operated at a temperature within the range of from <NUM> to <NUM>, preferably from <NUM> to <NUM>. The pressure is suitably from <NUM> to <NUM> bar, preferably from <NUM> to <NUM> bar.

According to this invention the first polypropylene (PP1) is produced in the first step, i.e. in a first reactor, e.g. the loop reactor, whereas the second polypropylene (PP2) is produced in the subsequent step, i.e. in the second reactor, e.g. the gas phase reactor. In case the polymerization process of the first polypropylene (PP1) and the second polypropylene (PP2) contains also a prepolimerization step, then the first polypropylene (PP1) according to this invention is the polymer produced in the prepolymerization together with the polymer produced in the subsequent first step, in the first reactor, e.g. the loop reactor, whereas the second polypropylene (PP2) is the product of the second reactor, e.g. the gas phase reactor. The amount of polymer produced in the prepolymerization step is comparatively small compared to the quantities produced in the first reactor and therefore has no great influence on the properties of the polypropylene from the first reactor.

The first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, like in the range of <NUM> to <NUM>/<NUM>.

Further it is required that the alpha-nucleated polypropylene composition (n-PP) in case it contains a comonomer then the comonomer is selected from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. Further the comonomer content shall be in the alpha-nucleated polypropylene composition (n-PP) not more than <NUM> mol. Accordingly the first polypropylene (PP1) may contain a comonomer selected from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene as well. However the comonomer content of the first polypropylene (PP1) is not more than <NUM> mol-%. It is especially preferred that the first polypropylene (PP1) is a propylene homopolymer or a propylene-<NUM>-butene copolymer having a <NUM>-butene content in the range of <NUM> to <NUM> mol-%. It is in particular preferred that the first polypropylene (PP1) is a propylene homopolymer.

Accordingly it is especially preferred that the first polypropylene (PP1) is a propylene homopolymer having a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>. It is in particular preferred that the first polypropylene (PP1) is a propylene homopolymer having a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, like in the range of <NUM> to <NUM>/<NUM>.

Similar to the first polypropylene (PP1), the second polypropylene (PP2) may contain a comonomer. In such a case the comonomer is selected from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. Further the comonomer content shall be in the alpha-nucleated polypropylene composition (n-PP) not more than <NUM> mol. Therefore the comonomer content of the second polypropylene (PP2) is not more than <NUM> mol-%. It is especially preferred that the second polypropylene (PP1) is a propylene homopolymer or a propylene-<NUM>-butene copolymer having a <NUM>-butene content in the range of <NUM> to <NUM> mol-%. It is in particular preferred that the second polypropylene (PP2) is a propylene homopolymer.

Thus it is especially preferred that the alpha-nucleated polypropylene composition (n-PP) comprises the first polypropylene (PP1) and the second polypropylene (PP2) in a weight ratio in the range of <NUM>/<NUM> to <NUM>/<NUM> wherein the first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and wherein further the first polypropylene (PP1) and the second polypropylene (PP2) each by itself has a comonomer content in the range of <NUM> to <NUM> mol-% and both polymers contain the same comonomer selected from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. It is in particular preferred that the alpha-nucleated polypropylene composition (n-PP) comprises the first polypropylene (PP1) and the second polypropylene (PP2) in a weight ratio in the range of <NUM>/<NUM> to <NUM>/<NUM> wherein the first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and wherein further the first polypropylene (PP1) and the second polypropylene (PP2) are propylene-<NUM>-butene copolymers each of the two polymers has a comonomer content in the range of <NUM> to <NUM> mol-%.

It is in particular preferred that the alpha-nucleated polypropylene composition (n-PP) comprises the first polypropylene (PP1) and the second polypropylene (PP2) in a weight ratio in the range of <NUM>/<NUM> to <NUM>/<NUM> wherein the first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and wherein further the first polypropylene (PP1) and the second polypropylene (PP2) are both propylene homopolymers.

The melt flow rate MFR<NUM> (<NUM>; <NUM>) of the alpha-nucleated polypropylene composition (n-PP) differs essentially from the melt flow rate MFR<NUM> (<NUM>; <NUM>) of the first polypropylene (PP1). Accordingly the alpha-nucleated polypropylene composition (n-PP) complies with equation <NUM>, preferably equation 3a, <MAT> <MAT> wherein.

Accordingly the melt flow rate MFR<NUM> (<NUM>; <NUM>) of the second polypropylene (PP2) must be higher than the melt flow rate MFR<NUM> (<NUM>; <NUM>) of the first polypropylene (PP1). It is in particular preferred that the melt flow rate MFR<NUM> (<NUM>; <NUM>) of the second polypropylene (PP2) is in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>. These values are calculated as mentioned in the experimental part.

Thus it is especially preferred that the alpha-nucleated polypropylene composition (n-PP) comprises the first polypropylene (PP1) and the second polypropylene (PP2) in a weight ratio in the range of <NUM>/<NUM> to <NUM>/<NUM> wherein the first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and the second polypropylene (PP2) has a melt flow rate MFR<NUM> (<NUM>; <NUM>) in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and wherein further the first polypropylene (PP1) and the second polypropylene (PP2) each by itself has a comonomer content in the range of <NUM> to <NUM> mol-% and both polymers contain the same comonomer selected from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. It is in particular preferred that the alpha-nucleated polypropylene composition (n-PP) comprises the first polypropylene (PP1) and the second polypropylene (PP2) in a weight ratio in the range of <NUM>/<NUM> to <NUM>/<NUM> wherein the first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and the second polypropylene (PP2) has a melt flow rate MFR<NUM> (<NUM>; <NUM>) in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and wherein further the first polypropylene (PP1) and the second polypropylene (PP2) are propylene-<NUM>-butene copolymers each of the two polymers has a comonomer content in the range of <NUM> to <NUM> mol-%.

It is in particular preferred that the alpha-nucleated polypropylene composition (n-PP) comprises the first polypropylene (PP1) and the second polypropylene (PP2) in a weight ratio in the range of <NUM>/<NUM> to <NUM>/<NUM> wherein the first polypropylene (PP1) has a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and the second polypropylene (PP2) has a melt flow rate MFR<NUM> (<NUM>; <NUM>) in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, and wherein further the first polypropylene (PP1) and the second polypropylene (PP2) are both propylene homopolymers.

Thus the invention is especially directed to an alpha-nucleated polypropylene composition (n-PP) being an alpha-nucleated propylene homopolymer, wherein said alpha-nucleated polypropylene composition (n-PP) comprises.

Accordingly, the present invention is in particular directed to an alpha-nucleated polypropylene composition (n-PP) being an alpha-nucleated propylene homopolymer, wherein said alpha-nucleated polypropylene composition (n-PP) comprises.

As mentioned above the alpha-nucleated polypropylene composition (n-PP) must comprise an alpha nucleating agent. Alpha-nucleating agents are well known in the art. Reference is made to the "<NPL>.

Generally, alpha-nucleating agents promote the formation of crystallization nuclei when a melt of polypropylene is solidified and are thus increasing the crystallization speed and temperature of the alpha-nucleated polypropylene compared to non-alpha-nucleated polypropylene.

The alpha-nucleated polypropylene composition (n-PP) usually contains up to <NUM> wt. -% of alpha-nucleating agent. A lower limit of <NUM> wt. -% of alpha-nucleating agent is preferred. Preferably the polypropylene composition (n-PP) comprises <NUM> to <NUM> wt. -%, more preferably <NUM> to <NUM> wt. -%, yet more preferably <NUM> to <NUM> wt. -%, of alpha-nucleating agent. The weight percent in the afore paragraph refers to the total amount of alpha-nucleating agents present in the alpha-nucleated polypropylene composition (n-PP).

Preferred examples of the alpha-nucleating agents are disclosed in "<NPL>.

Among all alpha-nucleating agents, aluminium hydroxy-bis[<NUM>,<NUM>,<NUM>,<NUM>-tetrakis(<NUM>,<NUM>-dimethylethyl)-<NUM>-hydroxy-<NUM>-dibenzo-[d,g]-dioxa-phoshocin-<NUM>-oxidato] based nucleating agents like ADK NA-<NUM>, NA-<NUM> E, NA-<NUM> F, etc., sodium-<NUM>,<NUM>'-methylene-bis(<NUM>,<NUM>-di-t-butylphenyl)phosphate (ADK NA-<NUM>), aluminium-hydroxy-bis[<NUM>,<NUM>'-methylene-bis(<NUM>,<NUM>-di-t-butyl-phenyl)-phosphate], sorbitol-based nucleating agents, i.e. di(alkylbenzylidene)sorbitols like <NUM>,<NUM>:<NUM>,<NUM>-<NUM> dibenzylidene sorbitol, <NUM>,<NUM>:<NUM>,<NUM>-di(<NUM>-methylbenzylidene) sorbitol, <NUM>,<NUM>:<NUM>,<NUM>-di(<NUM>-ethylbenzylidene) sorbitol and <NUM>,<NUM>:<NUM>,<NUM>-Bis(<NUM>,<NUM>-dimethylbenzylidene) sorbitol, as well as nonitol derivatives, like <NUM>,<NUM>,<NUM>-trideoxy-<NUM>,<NUM>;<NUM>,<NUM>-bis-O-[(<NUM>-propylphenyl)methylene] nonitol, and benzene-trisamides like substituted <NUM>,<NUM>,<NUM>-benzenetrisamides as N,N',N"-tris-tert-butyl-<NUM>,<NUM>,<NUM>-benzenetricarboxamide, N,N',N"-tris-cyclohexyl-<NUM>,<NUM>,<NUM>-benzene-tricarboxamide and N-[<NUM>,<NUM>-bis-(<NUM>,<NUM>-dimethyl-propionylamino)-phenyl]-<NUM>,<NUM>-dimethyl-propionamide, wherein <NUM>,<NUM>:<NUM>,<NUM>-di(<NUM>-methylbenzylidene) sorbitol and N-[<NUM>,<NUM>-bis-(<NUM>,<NUM>-dimethyl-propionylamino)-phenyl]-<NUM>,<NUM>-dimethyl-propionamide and polymeric nucleating agents selected from the group consisting of vinylcycloalkane polymers and vinylalkane polymers are particularly preferred.

Especially preferred are soluble nucleating agents like Millad <NUM> (<NUM>,<NUM>:<NUM>,<NUM>-di(<NUM>-ethylbenzylidene) sorbitol and <NUM>,<NUM>:<NUM>,<NUM>-Bis(<NUM>,<NUM>-dimethylbenzylidene) sorbitol) and Millad NX8000 (<NUM>,<NUM>,<NUM>-trideoxy-<NUM>,<NUM>;<NUM>,<NUM>-bis-O-[(<NUM>-propylphenyl)methylene] nonitol).

It is in particular preferred that the alpha-nucleating agent(s) present in the alpha-nucleated polypropylene composition (n-PP) is/are selected from the group consisting of poly vinylcyclohexane (p-VCH), <NUM>,<NUM>,<NUM>-trideoxy-<NUM>,<NUM>;<NUM>,<NUM>-bis-O-[(<NUM>-propylphenyl)methylene] nonitol and bis-(<NUM>,<NUM>-dimethylbenzylidene)-sorbitol (DMDBS), wherein further the total amount of the alpha-nucleating agent(s), based on the total amount of the alpha-nucleated polypropylene composition (n-PP), is in the range of <NUM> to <NUM> wt.

The present invention is furthermore directed to thin wall injection molded article consisting of the alpha-nucleated polypropylene composition (n-PP) as defined above, wherein the thin wall injection molded article has a wall thickness up to <NUM>, preferably in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>, yet more preferably in the range of <NUM> to <NUM>. The manufacture of thin wall injection molded articles is well known in the art and for instance described in "Polypropylene Handbook" <NUM>nd Edition of Nello Pasquini, pages <NUM>/<NUM>.

In the following the present invention is described further by way of examples.

The following definitions of terms and determination methods apply for the above general description of the invention including the claims as well as to the below examples unless otherwise defined.

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the isotacticity and regio-regularity of the propylene homopolymers.

Quantitative <NUM>C{<NUM>H} NMR spectra were recorded in the solution-state using a Bruker Advance III <NUM> NMR spectrometer operating at <NUM> and <NUM> for <NUM>H and <NUM>C respectively. All spectra were recorded using a <NUM>C optimised <NUM> extended temperature probehead at <NUM> using nitrogen gas for all pneumatics.

For propylene homopolymers approximately <NUM> of material was dissolved in <NUM>,<NUM>-tetrachloroethane-d<NUM> (TCE-d<NUM>). To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatary oven for at least <NUM> hour. Upon insertion into the magnet the tube was spun at <NUM>. This setup was chosen primarily for the high resolution needed for tacticity distribution quantification (<NPL>; <NPL>). Standard single-pulse excitation was employed utilising the NOE and bi-level WALTZ16 decoupling scheme (<NPL>;<NPL>). A total of <NUM> (<NUM>) transients were acquired per spectra.

Quantitative <NUM>C{<NUM>H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs.

For propylene homopolymers all chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at <NUM> ppm.

Characteristic signals corresponding to regio defects (<NPL>; <NPL>;<NPL>) or comonomer were observed.

The tacticity distribution was quantified through integration of the methyl region between <NUM>-<NUM> ppm correcting for any sites not related to the stereo sequences of interest (<NPL>;<NPL>).

Specifically the influence of regio-defects and comonomer on the quantification of the tacticity distribution was corrected for by subtraction of representative regio-defect and comonomer integrals from the specific integral regions of the stereo sequences.

The isotacticity was determined at the pentad level and reported as the percentage of isotactic pentad (mmmm) sequences with respect to all pentad sequences: <MAT>.

The presence of <NUM>,<NUM> erythro regio-defects was indicated by the presence of the two methyl sites at <NUM> and <NUM> ppm and confirmed by other characteristic sites. Characteristic signals corresponding to other types of regio-defects were not observed (<NPL>).

The amount of <NUM>,<NUM> erythro regio-defects was quantified using the average integral of the two characteristic methyl sites at <NUM> and <NUM> ppm: <MAT>.

The total amount of propene was quantified as the sum of primary inserted propene and all other present regio-defects: <MAT>.

The mole percent of <NUM>,<NUM> erythro regio-defects was quantified with respect to all propene: <MAT>.

The melt flow rate (MFR) is determined according to ISO <NUM> and is indicated in g/<NUM>. The MFR is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR<NUM> of the polypropylene is determined at a temperature of <NUM> and a load of <NUM>.

Calculation of melt flow rate MFR<NUM> (<NUM>) of the second polypropylene (PP2): <MAT> wherein.

Molecular weight averages (Mz, Mw and Mn) and Molecular weight distribution (MWD), i.e. Mw/Mn, were determined by Gel Permeation Chromatography (GPC) according to ISO <NUM>-<NUM>:<NUM> and ASTM D <NUM>-<NUM> using the following formulas: <MAT> <MAT> <MAT> where Ai and Mi are the chromatographic peak slice area and polyolefin molecular weight (MW).

A PolymerChar GPC instrument, equipped with infrared (IR) detector was used with <NUM> × Olexis and 1x Olexis Guard columns from Polymer Laboratories and <NUM>,<NUM>,<NUM>-trichlorobenzene (TCB, stabilized with <NUM>/l <NUM>,<NUM>-Di-tert-butyl-<NUM>-methyl-phenol) as solvent at <NUM> and at a constant flow rate of <NUM>/min. <NUM>µL of sample solution were injected per analysis. The column set was calibrated using universal calibration (according to ISO <NUM>-<NUM>:<NUM>) with at least <NUM> narrow MWD polystyrene (PS) standards in the range of <NUM>/mol to <NUM>/mol. Mark Houwink constants used for PS, PE and PP are as described per ASTM D <NUM>-<NUM>. All samples were prepared by dissolving <NUM> to <NUM> of polymer in <NUM> (at <NUM>) of stabilized TCB (same as mobile phase) for <NUM> hours for PP or <NUM> hours for PE at <NUM> under continuous gentle shaking in the autosampler of the GPC instrument.

The Flexural Modulus is determined according to ISO <NUM> method A (<NUM>-point bending test) on <NUM> × <NUM> × <NUM> specimens. Following the standard, a test speed of <NUM>/min and a span length of <NUM> times the thickness was used. The testing temperature was <NUM>±<NUM>° C. Injection moulding was carried out according to ISO <NUM>-<NUM> using a melt temperature of <NUM> for all materials irrespective of material melt flow rate.

Haze was determined according to ASTM D1003-<NUM> on 60x60x1 mm<NUM> plaques injection molded in line with EN ISO <NUM>-<NUM> using a melt temperature of <NUM>.

Q200 differential scanning calorimetry (DSC) on <NUM> to <NUM> samples. Highest crystallization peak temperature (Tp,c) and heat of crystallization (Hc) are determined from the cooling step, while highest melting peak temperature (Tp,m) and heat of fusion (Hf) are determined from the second heating step.

The amount of the polymer soluble in xylene was determined at <NUM> according to ISO <NUM>; 5th edition; <NUM>-<NUM>-<NUM>.

The following metallocene complex has been used as described in <CIT>:
<CHM>.

A steel reactor equipped with a mechanical stirrer and a filter net was flushed with nitrogen and the reactor temperature was set to <NUM>. Next silica grade DM-L-<NUM> from AGC Si-Tech Co, pre-calcined at <NUM> (<NUM>) was added from a feeding drum followed by careful pressuring and depressurising with nitrogen using manual valves. Then toluene (<NUM>) was added. The mixture was stirred for <NUM>. Next <NUM> wt. % solution of MAO in toluene (<NUM>) from Lanxess was added via feed line on the top of the reactor within <NUM>. The reaction mixture was then heated up to <NUM> and stirred at <NUM> for additional two hours. The slurry was allowed to settle and the mother liquor was filtered off. The catalyst was washed twice with toluene (<NUM>) at <NUM>, following by settling and filtration. The reactor was cooled off to <NUM> and the solid was washed with heptane (<NUM>). Finally MAO treated SiO<NUM> was dried at <NUM> under nitrogen flow for <NUM> hours and then for <NUM> hours under vacuum (-<NUM> barg) with stirring. MAO treated support was collected as a free-flowing white powder found to contain <NUM>% Al by weight.

% MAO in toluene (<NUM>) was added into a steel nitrogen blanked reactor via a burette at <NUM>. Toluene (<NUM>) was then added under stirring. The metallocene complex as described above under 2a) (<NUM>) was added from a metal cylinder followed by flushing with <NUM> toluene. The mixture was stirred for <NUM> minutes at <NUM>. Trityl tetrakis(pentafluorophenyl) borate (<NUM>) was then added from a metal cylinder followed by a flush with <NUM> of toluene. The mixture was stirred for <NUM> at room temperature. The resulting solution was added to a stirred cake of MAO-silica support prepared as described above over <NUM> hour. The cake was allowed to stay for <NUM> hours, followed by drying under N<NUM> flow at <NUM> for <NUM> and additionally for <NUM> under vacuum (-<NUM> barg) under stirring stirring.

Single site catalyst system <NUM> (SSCS2) has been prepared according to comparative example (CCS4) of <CIT>.

Claim 1:
Alpha-nucleated polypropylene composition (n-PP) comprising
(a) a first polypropylene (PP1) having a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>,
(b) a second polypropylene (PP2), and
(c) an alpha-nucleating agent,
wherein
- the weight ratio between the first polypropylene (PP1) and the second polypropylene (PP2) [(PP1)/(PP2)] is in the range of <NUM>/<NUM> to <NUM>/<NUM>, and
- the total amount of the first polypropylene (PP1) and the second polypropylene (PP2) together, based on the alpha-nucleated polypropylene composition (n-PP), is at least <NUM> wt.-%;
wherein further the alpha-nucleated polypropylene composition (n-PP) has
(i) a melt flow rate MFR<NUM> (<NUM>; <NUM>), measured according to ISO <NUM>, in the range of <NUM> to <NUM>/<NUM>;
(ii) a molecular weight distribution (MWD) determined by Gel Permeation Chromatography (GPC) in the range of <NUM> to <NUM>;
(iii) <NUM>,<NUM> erythro regio-defects in the range of ><NUM> to <NUM> mol-% measured by <NUM>C NMR; and
(iv) a comonomer content of not more than <NUM> mol-%, wherein the comonomer is selected from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene.