Patent Description:
Injection molded parts for thin-walled packaging applications such as food packaging and plastic cups place specific requirements on the polymeric materials employed to produce these articles. Of paramount importance for these mass production applications is a good processability, which generally manifests itself in a high melt flow rate of the corresponding compositions. On the other hand, the articles must provide sufficient stiffness to hold the content such as foodstuffs contained therein as well as having sufficient stiffness to be stacked. Finally, the materials should also withstand mechanical compression damage, which is frequently caused by e.g. dropping the articles. Polypropylene-based polymers have many characteristics, which make them suitable for applications such as molded articles, but also pipes, fittings and foams. Frequently, polypropylene products of high stiffness are based on high molecular weight materials, which are often nucleated by adding nucleating agents, i.e. crystallization starts at a higher temperature and the crystallization speed is high. However, to increase the output rate during extrusion, a polymer of high flowability is generally preferred. This processability requirement can be achieved by low molecular weight compositions with a low viscosity, i.e. high melt flow rate (MFR) compositions, which albeit usually have less stiffness. In addition, stiffness affording compositions are usually brittle and thus products generated from these materials display poor impact resistance and are susceptible to structural damage when dropped. Therefore, a general problem for polypropylene compositions used in these applications is to reconcile the opposed requirements of high processability, stiffness, impact strength and toughness.

In this context, <CIT> discloses a polyolefin composition comprising (A) from <NUM> to <NUM> wt. %; of a copolymer of propylene and <NUM>-hexene wherein said copolymer comprises from <NUM> to <NUM> wt. % of recurring units derived from <NUM>-hexene; and (B) from <NUM> to <NUM> wt. % of a heterophasic polypropylene composition comprising (B1) from <NUM> to <NUM> wt. % of a propylene homopolymer, said propylene polymer being insoluble in xylene at ambient temperature in an amount over <NUM> wt. % having a polydispersity index ranging from <NUM> to <NUM>; and a melt index from <NUM> to <NUM> dg/min; and (B2) from <NUM> to <NUM> wt. % of a copolymer of ethylene and propylene having an ethylene derived units content ranging from <NUM>% to <NUM>%; said polymeric composition having a melt index from <NUM> to <NUM> dg/min.

<CIT> discloses a heterophasic polypropylene composition with a high melt flow rate, good stiffness and an improved compression performance. The composition comprises a heterophasic propylene copolymer comprising: (a) a matrix phase (A) comprising a propylene homopolymer and/or a propylene copolymer, and (b) a disperse phase (B) comprising a propylene copolymer rubber dispersed in matrix phase (A), wherein (i) the polypropylene composition has a melt flow rate MFR<NUM> of <NUM>/<NUM> or higher, (ii) the propylene copolymer rubber of the disperse phase (B) has a comonomer content of <NUM> wt. % or higher, and (iii) the intrinsic viscosity IV of the disperse phase (B) and the MFR<NUM> of the matrix phase (A) fulfil a specific relationship. These compositions may be employed for the production of molded articles, in particular injection molded articles such as thin-walled plastic cups.

Impact copolymers (or heterophasic copolymers, HECOs) are widely used in different application areas like thin-wall packaging (TWP), films, automotive applications, due to their excellent cost/performance. In some application areas, e.g. TWP, the toughness, especially the puncture energy, is very important, beside the stiffness. It is believed that puncture energy is related to the drop height in TWP, the higher the puncture, the higher the drop height. However, problems occur when trying to reconcile the opposing properties of toughness and stiffness, i. e improvement of toughness leads to a deterioration of stiffness.

<CIT> discloses a polyolefin composition comprising A) <NUM>-<NUM>% of a copolymer of propylene and <NUM>-hexene wherein said copolymer comprises from <NUM> to <NUM> % of recurring units derived from hexene-<NUM>; and B) <NUM>-<NUM>% of a heterophasic polypropylene comprising: B1) <NUM>-<NUM>% of a propylene polymer and B2) <NUM>-<NUM>% of a copolymer of ethylene with a C<NUM>-C<NUM> alpha-olefin and optionally a diene, having an ethylene content ranging from <NUM> to <NUM>% and an intrinsic viscosity value of at least <NUM> dl/g.

<CIT> discloses a propylene polymer composition comprising a heterophasic propylene copolymer and a propylene-hexene random copolymer and optional an alpha-nucleating agent, the composition having high flexural modulus, high Charpy notched impact strength (NIS) and low hexane content. The compositions may be used for cast or blown films suitable for sterilization treatment.

Therefore there is a need for heterophasic polypropylene compositions, which show high flowability and an improved impact/stiffness/toughness balance and are especially suitable for thin wall injection molded applications. Accordingly, it is an object of the present invention to provide such a composition. It is a further object to provide a multistage process for the preparation of such heterophasic polypropylene compositions having the above mentioned unique property balance. The present invention is based on the finding that the above objects can be achieved by a high melt flow heterophasic polypropylene composition in which a specific heterophasic propylene polymer comprising specific matrix and rubber design and a further copolymer are combined.

The above objects are achieved by a polypropylene composition comprising a blend of.

wherein the polypropylene composition has a MFR<NUM> (<NUM>, <NUM>, ISO <NUM>) in the range of from <NUM> to <NUM>/<NUM>.

The above objects can further be achieved by a process for the preparation of such polypropylene compositions the following stages (i) and (ii) in any sequence:.

wherein the propylene-hexene random copolymer (B) is blended with the heterophasic propylene copolymer (A) by mechanical blending or by in situ-polymerization in any order.

Still further, the above objects are achieved by the use of such polypropylene compositions for the production of molded articles, in particular injection-molded articles, preferably thin-wall molded articles.

The special combination of components (A), (B) and optionally (C) enable compositions having improved stiffness/impact/toughness balance compared to other heterophasic polypropylene compositions which provide unique advantages for molded articles as described in detail below.

In the following the individual components encompassed by the present invention are defined in more detail.

The particular polypropylene composition of the present invention comprises at least component (A) being a heterophasic propylene copolymer (HECO) comprising a matrix (M) being a being a propylene homopolymer (H-PP) and an elastomeric propylene copolymer (EPC) dispersed in said matrix (M); component (B) being a copolymer (CPH) of propylene and <NUM>-hexene; each component being defined as above and in more detail below.

The term "heterophasic polypropylene composition" used herein denotes compositions comprising the above heterophasic propylene copolymer (A), and the above copolymer of propylene and hexene (B).

In the present invention, the term "matrix" is to be interpreted in its commonly accepted meaning, i.e. it refers to a continuous phase (in the present invention a continuous polymer phase) in which isolated or discrete particles such as rubber particles may be dispersed. The propylene homo- or copolymer is present in such an amount that it can form a continuous phase which can act as a matrix.

Furthermore the terms "elastomeric propylene copolymer (EPC)", "xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer", "dispersed phase" and "ethylene propylene rubber" denote the same, i.e. are interchangeable.

As described above, the polypropylene composition of the present invention comprises <NUM> to <NUM> wt. %, preferably <NUM> to <NUM> wt. %, more preferably <NUM> to <NUM> wt. %, based on the total amount of the composition, of a heterophasic propylene copolymer (HECO) comprises at least a matrix (M) being a being a propylene homopolymer (H-PP) and an elastomeric propylene copolymer (EPC) dispersed in said matrix (M).

The HECO comprises, based on the total amount of the HECO, <NUM> to <NUM> wt. % of matrix (M) being a propylene homopolymer (H-PP) with a MFR<NUM>, (<NUM>, <NUM>, ISO <NUM>) of from <NUM> - <NUM>/<NUM>, preferably <NUM> - <NUM>/<NUM>, more preferably <NUM> - <NUM>/<NUM>.

Preferably, the final melt flow rate of the heterophasic propylene copolymer (HECO) is adjusted during the polymerization process. Accordingly, the reactor-made heterophasic propylene copolymer (HECO) has the melt flow rate as defined above or in the claims. "Reactor-made heterophasic propylene copolymer (HECO)" denotes herein that the melt flow rate of the heterophasic propylene copolymer (HECO) has not been modified on purpose by post-treatment. Accordingly, in preferred embodiments the heterophasic propylene copolymer (HECO) is non-visbroken, particularly not visbroken using peroxide. Accordingly, the melt flow rate is not increased by shortening the chain length of the heterophasic propylene copolymer (HECO) according to this invention by use of peroxide. Thus, it is preferred that the heterophasic propylene copolymer (HECO) does not contain any peroxide and/or decomposition product thereof.

The HECO further comprises an ethylene (C<NUM>) co-monomer content, determined from its xylene cold soluble (XCS) fraction according to ISO <NUM>; first edition, <NUM>-<NUM>-<NUM> at <NUM>, of from <NUM> to <NUM> wt. %, preferably from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt.

The total content of comonomers, i.e. the sum of content of ethylene and alpha-olefins with <NUM> to <NUM> C-atoms, in the total heterophasic propylene copolymer (A) (HECO) is preferably in the range of <NUM> to <NUM> wt%, more preferably in the range of <NUM> to <NUM> wt% and even more preferably in the range of <NUM> to <NUM> wt%. It is particularly preferred that the co-monomers are ethylene co-monomers only.

The heterophasic propylene copolymer may preferably have a melting temperature (Tm) in the range of from <NUM> to <NUM>, more preferably <NUM> to <NUM> and/or a crystallization temperature (Tc) of greater than <NUM>, more preferably <NUM> to <NUM>, even more preferably <NUM> to <NUM>, such as <NUM> to <NUM>, Tm and Tc being measured by differential scanning calorimetry (DSC).

The heterophasic propylene copolymer (HECO) comprises at least two and optionally three polypropylene fractions (PP1), (PP2), and (PP3).

In one preferred embodiment the matrix polypropylene (PP) comprises three polypropylene fractions (PP1), (PP2), and (PP3). In this case the matrix (M), i.e. the polypropylene (PP) of the heterophasic propylene copolymer (HECO) comprises, preferably consist of:.

The expression homopolymer used in the present invention relates to a polypropylene that consists substantially, i.e. of at least <NUM> wt%, preferably of at least <NUM> wt%, more preferably of at least <NUM> wt%, still more preferably of at least <NUM> wt% of propylene units. In a preferred embodiment only propylene units in the propylene homopolymer are detectable.

In Embodiment <NUM>, the three polypropylene fractions (PP1), (PP2), and (PP3) differ from each other by the melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM>. One of the three polypropylene fractions (PP1), (PP2), and (PP3), preferably the third polypropylene fraction (PP3), has a melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, still more preferably in the range of <NUM> to <NUM>/<NUM>. Still more preferably the polypropylene fraction with the melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, i.e. in the range of <NUM> to <NUM>/<NUM>, like in the range of <NUM> to <NUM>/<NUM>, is the polypropylene fraction with the lowest melt flow rate MFR<NUM> (<NUM>) of the three polypropylene fractions (PP1), (PP2) and (PP3), preferably of all polypropylene fractions present, of the polypropylene (PP). Accordingly in one preferred embodiment the third polypropylene fraction (PP3) has the lowest melt flow rate MFR<NUM> (<NUM>) of the three polypropylene fractions (PP1), (PP2), and (PP3), wherein the melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> of the third polypropylene fraction (PP3) is in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, still more preferably in the range of <NUM> to <NUM>/<NUM>.

In addition to the requirement that one of the three polypropylene fractions (PP1), (PP2) and (PP3) must have a melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM> it is preferred that another fraction of the three polypropylene fractions (PP1), (PP2) and (PP3) has a melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, more preferably in the range of <NUM> to <NUM>/<NUM>. Particularly the first polypropylene fraction (PP1) has a melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, more preferably in the range of <NUM> to <NUM>/<NUM>.

In one preferred embodiment the remaining polypropylene fraction of the three polypropylene fractions (PP1), (PP2) and (PP3), preferably the second polypropylene fraction (PP2), has a melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>, more preferably in the range of <NUM> to <NUM>/<NUM>.

Thus, the matrix (M) of Embodiment <NUM> is multimodal, e.g. trimodal. It preferably contains the three fractions (PP1), (PP2), and (PP3) in certain amounts. Fraction (PP1) is preferably present in an amount of <NUM> to <NUM> wt%, fraction (PP2) is preferably in present in an amount of <NUM> to <NUM> wt% and fraction (PP3) present in an amount of in <NUM> to <NUM> wt%, all weight percentages related to the matrix and summing up to <NUM>% of the matrix.

"Multimodal", like "bimodal" or "trimodal" describes a probability distribution that has several relative maxima. In particular, the expression "modality of a polymer" refers to the form ofits molecular weight distribution (MWD) curve, i.e. the appearance of the graph of the polymer weight fraction as a function of its molecular weight. If the polymer is produced in a sequential step process, i.e. by utilizing reactors coupled in serial configuration, and using different conditions in each reactor, the different polymer fractions produced in the different reactors have each their own molecular weight distribution which may considerably differ from one another. The molecular weight distribution curve of the resulting final polymer can be seen as super-imposing of molecular weight distribution curves of the individual polymer fractions which will, accordingly, show distinct maxima, or at least be distinctively broadened compared with the curves for individual fractions. A polymer showing such molecular weight distribution curve is called bimodal, trimodal or multimodal, respectively.

In a further preferred embodiment the matrix (M) comprises two polypropylene fractions (PP1) and (PP2). In this case the matrix (M), i.e. the polypropylene (PP) of the heterophasic propylene copolymer (HECO) comprises, preferably consist of:.

The polypropylene constituting the matrix in this case can be unimodal or multimodal, e.g. bimodal. When the matrix is bimodal, the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2) differ at least in their melt flow rate, optionally also in their comonomer content. According to one preferred embodiment, the melt flow rate of the (PP1) fraction is higher than the melt flow rate of the (PP2) fraction, the ratio MFR(PP1)/MFR(PP2) being in the range of <NUM> to <NUM>.

The propylene homo- or copolymer (PP) constituting the matrix for Embodiment <NUM> or Embodiment <NUM> may be produced by a single- or multistage process polymerization of propylene or propylene with alpha-olefin and/or ethylene such as bulk polymerization, gas phase polymerization, solution polymerization or combinations thereof, using conventional catalysts. A homo- or copolymer can be made either in loop reactors or in a combination of loop and gas phase reactors. Those processes are well known to the skilled person.

As stated above in both cases the matrix (M) is preferably a propylene homopolymer. When the propylene homopolymer matrix phase is unimodal with respect to the molecular weight distribution, it may be prepared in a single stage process e.g. a slurry (or bulk) or gas phase process in a slurry or gas phase reactor. Thus, a unimodal matrix phase may be polymerized in a slurry polymerization step only. Alternatively, the unimodal matrix may be produced in a multistage process (e.g. combination of slurry and gas phase) using at each stage process conditions which result in similar polymer properties.

A multimodal propylene homopolymer matrix may be produced by blending different polymer types, i.e. of different molecular weight and/or comonomer content. However in such a case it is preferred that the polymer components of the polypropylene matrix are produced in a sequential step process, using reactors in serial configuration and operating at different reaction conditions. As a consequence, each fraction prepared in a specific reactor will have its own molecular weight distribution and/or comonomer content distribution.

When the distribution curves (molecular weight or comonomer content) from these fractions are superimposed to obtain the molecular weight distribution curve or the comonomer content distribution curve of the final polymer, these curves may show two or more maxima or at least be distinctly broadened when compared with curves for the individual fractions. Such a polymer, produced in two or more serial steps, is called bimodal or multimodal, depending on the number of steps.

The propylene homopolymer matrix has a melt flow rate MFR, (ISO <NUM>; <NUM>; <NUM>) in the range of <NUM> to <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM> and more preferably in the range of <NUM> to <NUM>/<NUM>. The MFR<NUM> of the matrix is named matrix melt flow rate (MFRM).

Moreover it is preferred that the amount of xylene solubles of the propylene homopolymer matrix is not too high. Xylene solubles are the part of the polymer soluble in cold xylene determined by dissolution in boiling xylene and letting the insoluble part crystallize from the cooling solution (determined at <NUM> according to ISO <NUM>, first edition, <NUM>-<NUM>-<NUM>). The xylene solubles fraction contains polymer chains of low stereo-regularity and is an indication for the amount of non-crystalline areas. Accordingly, it is preferred that the xylene solubles fraction of the propylene homopolymer matrix is in the range of <NUM> wt% to <NUM> wt%, more preferably in the range of <NUM> wt% to <NUM> wt%. In an even more preferred embodiment the xylene solubles fraction is in the range of <NUM> wt% to <NUM> wt%.

As stated above, the propylene homopolymer matrix can be unimodal or multimodal, e.g. bimodal or trimodal.

The elastomeric propylene copolymer (EPC) dispersed in the matrix (M), described above may preferably be a copolymer of propylene and ethylene and/or an alpha-olefin with <NUM>-<NUM> carbon atoms or any combination thereof, being dispersed in said matrix (M) (i.e. dispersed phase), and said elastomeric propylene copolymer (EPC) comprises at least one propylene copolymer fraction (EPC1) and optionally a second propylene copolymer fraction (EPC2). Thus, the elastomeric propylene copolymer (EPC) dispersed in the matrix (M) may be a unimodal or bimodal composition.

More preferably, the elastomeric propylene copolymer (EPC) is a copolymer of propylene and ethylene.

As stated above, the terms "elastomeric propylene copolymer (EPC)", "xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer", "dispersed phase" and "ethylene propylene rubber" denote the same, i.e. are interchangeable.

Thus the amount of elastomeric propylene copolymer (EPC) constitutes the amount of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer, determined according to ISO <NUM>; first edition, <NUM>-<NUM>-<NUM> at <NUM>, which is in the range of <NUM> to <NUM> wt%, based on the total amount of the heterophasic propylene copolymer (HECO), preferably in the range of <NUM> to <NUM> wt% and more preferably in the range of <NUM> to <NUM> wt%.

The intrinsic viscosity (IV) of the XCS fraction is from <NUM> to <NUM> dl/g, preferably from <NUM> to <NUM> dl/g, more preferably from <NUM> to <NUM> dl/g, determined according to DIN ISO <NUM>/<NUM> in decalin at <NUM>.

In one embodiment, the dispersed phase is unimodal. More particularly, the dispersed phase is preferably unimodal in view of the intrinsic viscosity and/or the comonomer distribution. Concerning the definition of unimodal and multimodal, like bimodal, it is referred to the definition above. Preferably the unimodal dispersed phase is made in one reaction stage, more preferably in a gas phase reactor ad comprises, respectively consists of one propylene copolymer fractions (EPC1).

In another embodiment the dispersed phase comprises, preferably consists of two fractions, e.g. one propylene copolymer fractions (EPC1) and a second propylene copolymer fraction (EPC2).

These two fractions are preferably in-situ blended. The fractions (EPC1) and (EPC2) are preferably obtainable as described later. In this case the two fractions (EPC1) and (EPC2) differ in view of the intrinsic viscosity and/or the comonomer distribution.

Preferably, the first elastomeric propylene copolymer fractions (EPC1) has a comonomer content in the range of <NUM> - <NUM> wt%, more preferably, in the range <NUM> - <NUM> wt % and most preferably in the range of <NUM> - <NUM> wt %.

Preferably, the first elastomeric propylene copolymer fractions (EPC1) has an intrinsic viscosity (iV) measured according to ISO <NUM>/<NUM> (at <NUM> in decalin) of <NUM> - <NUM> dl/g, more preferably of <NUM> - <NUM> dl/g still more preferably of <NUM> - <NUM> dl/g.

The second elastomeric propylene copolymer fractions (EPC2) preferably has a comonomer content in the range of <NUM> - <NUM> wt%, more preferably in the range of <NUM> - <NUM> wt% and most preferably within the range of <NUM> - <NUM> wt%.

The second elastomeric propylene copolymer fractions (EPC2) preferably has an intrinsic viscosity (IV) measured according to ISO <NUM>/<NUM> (at <NUM> in decalin) of <NUM> - <NUM> dl/g, more preferably of <NUM> - <NUM> dl/g and most preferably of <NUM> - <NUM> dl/g.

The comonomer content of each of the first elastomeric propylene copolymer fractions (EPC1) and the second elastomeric propylene copolymer fractions (EPC2) can be measured for the first elastomeric propylene copolymer fractions (EPC1) and the mixture of first elastomeric propylene copolymer fractions (EPC1) and second elastomeric propylene copolymer fractions (EPC2). The second propylene copolymer fraction (EPC2) is then calculated. The calculation of the comonomer content is given below in the example section.

If the elastomeric propylene copolymer (EPC) is prepared separately from the polypropylene constituting the matrix, it can be subsequently blended with the matrix polymer by any conventional blending means, e.g. melt blending in an extruder.

Alternatively, the elastomeric propylene copolymer (EPC) can be prepared as a reactor blend together with the propylene homo- and/or copolymer (PP) constituting the matrix (M), e.g. starting with the production of the matrix polymer in a slurry, e.g. loop reactor and optionally a gas phase reactor, followed by transferring the product into one or more gas phase reactors, where the elastomeric propylene copolymer (EPC) is polymerized.

As described above, the heterophasic propylene copolymer (HECO) of the present invention comprises components (A-<NUM>) which is the matrix phase, and (A-<NUM>) which is the elastomeric propylene copolymer (EPC) dispersed in the matrix phase, and optional components (C).

The heterophasic propylene copolymer (HECO) according to the present invention apart from the polymeric components and the nucleating agent (C), may comprise further non-polymeric components, e.g. additives for different purposes.

The following are optional additives: process and heat stabilisers, pigments and other colouring agents allowing retaining transparency, antioxidants, antistatic agents, slip agents, antiblocking agent, UV stabilisers and acid scavengers. Depending on the type of additive, these may be added in an amount of <NUM> to <NUM> wt%, based on the weight of the heterophasic propylene copolymer (HECO).

The polypropylene composition of the present invention comprises, besides component (A) described above, component (B) which is a copolymer (CPH) of propylene and <NUM>-hexene in an amount of from <NUM> to <NUM> wt. %, preferably from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. %, based on the total amount of the composition.

The copolymer (CPH) of propylene and <NUM>-hexene is preferably a propylene-hexene random copolymer and has a hexene content in the range of from <NUM> to <NUM> wt%, preferably in the range of from <NUM> to <NUM> wt% and more preferably in the range of from <NUM> to <NUM> wt%.

The MFR<NUM> (<NUM>, <NUM>, ISO1133) of the propylene-hexene random copolymer is in the range of from <NUM> to <NUM>/<NUM>, preferably in the range of from <NUM> to <NUM>/<NUM>, more preferably in the range of from <NUM> to <NUM>/<NUM> and yet more preferably in the range of from <NUM> to <NUM>/<NUM>.

The copolymer (CPH) of propylene and <NUM>-hexene comprises.

According to a preferred embodiment, the first random propylene copolymer (A) is a copolymer of propylene and a <NUM>-hexene having a <NUM>-hexene content in the range of <NUM> to <NUM> wt. -%, 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. -%, and the second random propylene copolymer (B) is a copolymer of propylene and <NUM>-hexene having an <NUM>-hexene content in the range of <NUM> to <NUM> wt. -%, 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.

Accordingly, the first random propylene copolymer (A) in this embodiment is the <NUM>-hexene lean fraction, whereas the second random propylene copolymer (B) is the <NUM>-hexene rich fraction.

Even more preferably, with regard to the melt flow rate MFR<NUM>, the copolymer (CPH) of propylene and <NUM>-hexene may fulfil in-equation (<NUM>), still more preferably in-equation (1a), even more preferably in-equation (1b), <MAT> <MAT> <MAT> wherein MFR(B-<NUM>) is the melt flow rate MFR<NUM> (<NUM>, <NUM>) determined according to ISO <NUM> in [g/<NUM>] of the first random propylene copolymer (B-<NUM>) and MFR(B-<NUM>) is the melt flow rate MFR<NUM> (<NUM>, <NUM>) determined according to ISO <NUM> in [g/<NUM>] of the copolymer (B-<NUM>).

Further, it is appreciated that the first random propylene copolymer (B-<NUM>) may preferably have a melt flow rate MFR<NUM> (<NUM>, <NUM>) determined according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, more preferably in the range of <NUM> to <NUM>/<NUM>, still more preferably in the range of <NUM> to <NUM>/<NUM>, like in the range of <NUM> to <NUM>/<NUM>.

The second random propylene copolymer (B-<NUM>) may preferably have a melt flow rate MFR<NUM> (<NUM>, <NUM>) determined according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, more preferably in the range of <NUM> to <NUM>/<NUM>, still more preferably in the range of <NUM> to <NUM>/<NUM>, like in the range of <NUM> to <NUM>/<NUM>.

Preferably, the weight ratio between the first random propylene copolymer (B-<NUM>) and the second random propylene copolymer (B-<NUM>) is in the range of <NUM>:<NUM> to <NUM>:<NUM>, more preferably in the range of <NUM>:<NUM> to <NUM>:<NUM>, still more preferably in the range of <NUM>:<NUM> to <NUM>:<NUM>.

Preferably, the copolymer (CPH) of propylene and <NUM>-hexene has a xylene soluble content (XCS) in the range of from <NUM> to <NUM> wt. %, more preferably <NUM> to <NUM> wt. %, even more preferably <NUM> to <NUM> wt. %, such as <NUM> to <NUM> wt. %, determined according to ISO <NUM>; first edition, <NUM>-<NUM>-<NUM> at <NUM>.

The melting temperature Tm of the copolymer (CPH) of propylene and <NUM>-hexene is in the range of from <NUM> to <NUM>, preferably in the range of from <NUM> to <NUM> and more preferably in the range of <NUM> to <NUM>.

Preferably the copolymer (CPH) of propylene and <NUM>-hexene has a molecular weight distribution (Mw/Mn) in the range of <NUM> to <NUM> and more preferably in the range of <NUM> to <NUM>. Additionally or alternatively to the molecular weight distribution (Mw/Mn) as defined in the previous paragraph the copolymer (CPH) of propylene and <NUM>-hexene has preferably weight average molecular weight Mw in the range of <NUM> to <NUM>/mol, more preferably in the range of <NUM> to <NUM>/mol, like in the range of <NUM> to <NUM>/mol.

The propylene-hexene random copolymer as described above may preferably be prepared in the presence of a metallocene catalyst.

The metallocene catalyst can be a supported catalyst, using conventional supports or can be free from an external carrier. By free from an external carrier is meant that the catalyst does not contain an external support, such as an inorganic support, for example, silica or alumina, or an organic polymeric support material.

Preferably used are metallocene catalysts which are free from an external carrier.

Especially preferred metallocene catalysts for the preparation of the copolymer (CPH) of propylene and <NUM>-hexene are those described in <CIT>. Also the process for its preparation according to this document may preferably be adopted.

The heterophasic propylene copolymer (HECO) in accordance with the present invention may be prepared by any suitable process, including in particular blending processes such as mechanical blending, including mixing and melt blending processes and any combinations thereof as well as in-situ blending during the polymerization process. These can be carried out by methods known to the skilled person, including batch processes and continuous processes.

The heterophasic propylene copolymer (HECO) according to the present invention is preferably prepared by a sequential polymerization process, as described below, in the presence of a catalyst system comprising a Ziegler-Natta Catalyst (ZN-C), a co-catalyst (Co) and optionally an external donor (ED), as described below.

The term "sequential polymerization system" according to this invention indicates that the heterophasic propylene copolymer (HECO), preferably nucleated, is produced in at least three reactors connected in series. Accordingly, the present polymerization system comprises at least a pre-polymerization reactor (PR), a first polymerization reactor (R1) and a second polymerization reactor (R2), a third polymerization reactor (R3) and optionally a fourth polymerization reactor (R4). The term "polymerization reactor" shall indicate that the main polymerization takes place.

Preferably, at least one of the two polymerization reactors (R1) and (R2) is a gas phase reactor (GPR). More preferably the second polymerization reactor (R2), the third polymerization reactor (R3) and the optional fourth polymerization reactor (R4) are gas phase reactors (GPRs), i.e. a first gas phase reactor (GPR1) and a second gas phase reactor (GPR2) and a third gas phase reactor (GPR3). A gas phase reactor (GPR) according to this invention is preferably a fluidized bed reactor, a fast fluidized bed reactor or a settled bed reactor or any combination thereof.

Accordingly, the first polymerization reactor (R1) is preferably a slurry reactor (SR) and can be any continuous or simple stirred batch tank reactor or loop reactor operating in bulk or slurry. Bulk means a polymerization in a reaction medium that comprises of at least <NUM> % (w/w) monomer. According to the present invention, the slurry reactor (SR) is preferably a (bulk) loop reactor (LR). In this first polymerization reactor (R1) the first polypropylene fraction (PP1), preferably the first propylene homopolymer fraction (H-PP1), of the matrix polypropylene (PP) is produced.

Preferably, the propylene homopolymer of the first polymerization reactor (R1), i.e. the first propylene homopolymer fraction (H-PP1), more preferably the polymer slurry of the loop reactor (LR) containing the first propylene homopolymer fraction (H-PP1), is directly fed into the second polymerization reactor (R2), i.e. into the (first) gas phase reactor (GPR1), without a flash step between the stages. This kind of direct feed is described in <CIT>, <CIT>, <CIT> and <CIT>.

By "direct feed" is meant a process wherein the content of the first polymerization reactor (R1), i.e. of the loop reactor (LR), the polymer slurry comprising the first propylene homopolymer fraction (H-PP1), is led directly to the next stage gas phase reactor.

Alternatively, the propylene homopolymer of the first polymerization reactor (R1), i.e. the first propylene homopolymer fraction (H-PP1), more preferably polymer slurry of the loop reactor (LR) containing the first propylene homopolymer fraction (H-PP1), may be also directed into a flash step or through a further concentration step before fed into the second polymerization reactor (R2), i.e. into the <NUM>% gas phase reactor (GPR1). Accordingly, this "indirect feed" refers to a process wherein the content of the first polymerization reactor (R1), of the loop reactor (LR), i.e. the polymer slurry, is fed into the second polymerization reactor (R2), into the (first) gas phase reactor (GPR1), via a reaction medium separation unit and the reaction medium as a gas from the separation unit.

More specifically, the second polymerization reactor (R2) and the third polymerization reactor (R3) and any subsequent reactor, for instance, the fourth polymerization reactor (R4) are preferably gas phase reactors (GPRs). Such gas phase reactors (GPR) can be any mechanically mixed or fluid bed reactors. Preferably, the gas phase reactors (GPRS) comprise a mechanically agitated fluid bed reactor with gas velocities of at least <NUM>/sec. Thus, it is appreciated that the gas phase reactor is a fluidized bed type reactor preferably with a mechanical stirrer.

Thus, in a preferred embodiment the first polymerization reactor (R1) is a slurry reactor (SR), like loop reactor (LR), whereas the second polymerization reactor (R2) and the third polymerization reactor (R3), and the optional fourth polymerization reactor (R4) are gas phase reactors (GPRs).

Accordingly, in the present process at least three, preferably three polymerization reactors (R1), (R2) and (R3) or four polymerization reactors (R1), (R2), (R3) and (R4), namely a slurry reactor (SR), like loop reactor (LR) and a (first) gas phase reactor (GPR1), a second gas phase reactor (GPR2), and optionally a third gas phase reactor (GPR3) connected in series are used.

Prior to the slurry reactor (SR) a pre-polymerization reactor is placed. As the process covers also a pre-polymerization step, all of the Ziegler-Natta catalyst (ZN-C) is fed in the pre-polymerization reactor. Subsequently the pre-polymerization product containing the Ziegler-Natta catalyst (ZN-C) is transferred into the first polymerization reactor (R1).

Especially good results are achieved in case the temperature in the reactors is carefully chosen. Accordingly it is preferred that the operating temperature in the first polymerization reactor (R1) is in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>.

Alternatively or additionally to the previous paragraph it is preferred that the operating temperature in the second polymerization reactor (R2) and in the third reactor (R3) and the optional the fourth reactor (R4) is in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>.

Preferably, the operating temperature in the second polymerization reactor (R2) is equal to or higher than the operating temperature in the first polymerization reactor (R1). Accordingly, it is preferred that the operating temperature.

Typically, the pressure in the first polymerization reactor (R1), preferably in the loop reactor (LR), is in the range from <NUM> to <NUM> bar, preferably <NUM> to <NUM> bar, like <NUM> to <NUM> bar, whereas the pressure in the second polymerization reactor (R2), i.e. in the (first) gas phase reactor (GPR1), and in any subsequent reactor, like in the third polymerization reactor (R3), e.g. in the second gas phase reactor (GPR2), or in a fourth polymerization reactor (R4), e.g. in the third gas phase reactor (GPR3) is in the range from <NUM> to <NUM> bar, preferably <NUM> to <NUM> bar. Preferably, hydrogen is added in each polymerization reactor in order to control the molecular weight, i.e. the melt flow rate MFR.

Preferably, the average residence time is rather long in the polymerization reactors (R1) and (R2). In general, the average residence time (<NUM>) is defined as the ratio of the reaction volume (VR) to the volumetric outflow rate from the reactor (Qo) (i.e. VR/Qo), i. e T = VR/Qo [tau = VR/Qo]. In case of a loop reactor the reaction volume (VR) equals to the reactor volume.

Accordingly, the average residence time (<NUM>) in the first polymerization reactor (R1) is preferably at least <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>, like in the range of <NUM> to <NUM>, and/or the average residence time (<NUM>) in the second polymerization reactor (R2) is preferably at least <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>, yet more preferably in the range of <NUM> to <NUM>, like in the range of <NUM> to <NUM>. Preferably the average residence time (<NUM>) in the third polymerization reactor (R3) or in the fourth polymerization reactor (R4) - if present- is preferably at least <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>, like in the range of <NUM> to <NUM>.

As mentioned above, the preparation of the heterophasic propylene copolymer (HECO) comprises in addition to the (main) polymerization of the propylene polymer in the at least three polymerization reactors (R1, R2, R3 and optional R4) prior thereto a pre-polymerization in a pre-polymerization reactor (PR) upstream to the first polymerization reactor (R1).

In the pre-polymerization reactor (PR) a polypropylene (Pre-PP) is produced. The prepolymerization is conducted in the presence of the Ziegler-Natta catalyst (ZN-C). According to this embodiment the Ziegler-Natta catalyst (ZN-C), the co-catalyst (Co), and the external donor (ED) are all introduced to the pre-polymerization step. However, this shall not exclude the option that at a later stage for instance further co-catalyst (Co) and/or external donor (ED) is added in the polymerization process, for instance in the first reactor (R1). In one embodiment the Ziegler-Natta catalyst (ZN-C), the co-catalyst (Co), and the external donor (ED) are only added in the pre-polymerization reactor (PR).

The pre-polymerization 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 pre-polymerization reactor is not critical but must be sufficiently high to maintain the reaction mixture in liquid phase. Thus, the pressure may be from <NUM> to <NUM> bar, for example <NUM> to <NUM> bar.

In a preferred embodiment, the pre-polymerization is conducted as bulk slurry polymerization in liquid propylene, i.e. the liquid phase mainly comprises propylene, with optionally inert components dissolved therein. Furthermore, according to the present invention, an ethylene feed can be employed during pre-polymerization as mentioned above.

It is possible to add other components also to the pre-polymerization stage. Thus, hydrogen may be added into the pre-polymerization stage to control the molecular weight of the polypropylene (Pre-PP) as is known in the art. Further, antistatic additive may be used to prevent the particles from adhering to each other or to the walls of the reactor. The precise control of the pre-polymerization conditions and reaction parameters is within the skill of the art.

Due to the above defined process conditions in the pre-polymerization, a mixture (MI) of the Ziegler-Natta catalyst (ZN-C) and the polypropylene (Pre-PP) produced in the prepolymerization reactor (PR) is obtained. Preferably, the Ziegler-Natta catalyst (ZN-C) is (finely) dispersed in the polypropylene (Pre-PP). In other words, the Ziegler-Natta catalyst (ZN-C) particles introduced in the pre-polymerization reactor (PR) split into smaller fragments which are evenly distributed within the growing polypropylene (Pre-PP). The sizes of the introduced Ziegler-Natta catalyst (ZN-C) particles as well as of the obtained fragments are not of essential relevance for the present invention and within the skilled knowledge.

Accordingly, the propylene polymer is preferably produced in a process comprising the following steps under the conditions set out above:.

Optionally, it is possible to transfer the entire polymer produced to a fourth polymerization reactor R4, i.e. either [H-PP1+H-PP2 + H-PP3] or [H-PP1+H-PP2 + EPC1], obtaining either a first propylene copolymer fractions (EPC1) or a second propylene copolymer fraction (EPC2) in the presence of all fractions produced in earlier steps.

Consequently, the preferably nucleated polymer produced may comprise the following fractions:.

By using - as stated above - a loop reactor and at one or two gas phase reactor in serial configuration and working at different conditions, a multimodal (e.g. bimodal or trimodal) propylene homopolymer matrix (M) can be obtained. If the loop reactor and the first gas phase reactor are run under conditions yielding similar polymers, a unimodal matrix can be obtained.

A preferred multistage process is a "loop-gas phase" process, as developed by Borealis (known as BORSTAR® technology) and is described e.g. in patent literature, such as in <CIT>, <CIT> <CIT>, <CIT>, <CIT>, <CIT> or in <CIT>. A further suitable slurry-gas phase process is the Spheripol® process of Basell.

The catalyst components are preferably all introduced to the prepolymerization step. However, where the solid catalyst component (i) and the co-catalyst (ii) can be fed separately it is possible that only a part of the co-catalyst is introduced into the prepolymerization stage and the remaining part into subsequent polymerization stages. Also in such cases it is necessary to introduce so much co-catalyst into the prepolymerization stage that a sufficient polymerization reaction is obtained therein.

It is possible to add other components also to the prepolymerization stage. Thus, hydrogen may be added into the prepolymerization stage to control the molecular weight of the prepolymer as is known in the art. Further, antistatic additive may be used to prevent the particles from adhering to each other or to the walls of the reactor. The precise control of the prepolymerization conditions and reaction parameters is within the skill of the art.

According to the present invention, the heterophasic propylene copolymer (HECO) is obtained by a multistage polymerization process, as described above, in the presence of a catalyst system. In the process described above a Ziegler-Natta catalyst (ZN-C) for the preparation of the heterophasic polypropylene composition is applied. This Ziegler-Natta catalyst (ZN-C) can be any stereo-specific Ziegler-Natta catalyst (ZN-C) for propylene polymerization, which preferably is capable of catalysing the polymerization and copolymerization of propylene and comonomers at a pressure of <NUM> to <NUM> kPa, in particular <NUM> to <NUM> kPa, and at a temperature of <NUM> to <NUM>, in particular of <NUM> to <NUM>.

Preferably, the Ziegler-Natta catalyst (ZN-C) comprises a high-yield Ziegler-Natta type catalyst including an internal donor component, which can be used at high polymerization temperatures of <NUM> or more. Such high-yield Ziegler-Natta catalyst (ZN-C) can comprise a non-phthalate based internal donor preferably selected from optionally substituted malonates, maleates, succinates, glutarates, cyclohexene-<NUM>,<NUM>-dicarboxylates, benzoates, a diether and derivatives and/or mixtures thereof, preferably from citraconates, or a phthalate-based donor, like DEHP, etc., or mixtures therefrom as internal donor (ID). The Ziegler-Natta catalyst (ZN-C) is preferably used in association with an alkyl aluminum co-catalyst (Co) and optionally external donors (ED). As further component in the instant polymerization process an external donor (ED) is preferably present. Suitable external donors include certain silanes, ethers, esters, amines, ketones, heterocyclic compounds and blends of these. It is especially preferred to use a silane. It is most preferred to use silanes of the general formula.

wherein Ra, Rb and Rc denote a hydrocarbon radical, in particular an alkyl or cycloalkyl group, and wherein p and q are numbers ranging from <NUM> to <NUM> with their sum p + q being equal to or less than <NUM>. Ra, Rb and Rc can be chosen independently from one another and can be the same or different. Specific examples of such silanes are (tert-butyl)<NUM>Si(OCH<NUM>)<NUM>, (cyclohexyl)(methyl)Si(OCH<NUM>)<NUM>, (phenyl)Si(OCH<NUM>)<NUM> and (cyclopentyl)<NUM>Si(OCH<NUM>)<NUM>, or of general formula.

wherein R<NUM> and R<NUM> can be the same or different a represent a hydrocarbon group having <NUM> to <NUM> carbon atoms.

R<NUM> and R<NUM> are independently selected from the group consisting of linear aliphatic hydrocarbon group having <NUM> to <NUM> carbon atoms, branched aliphatic hydrocarbon group having <NUM> to <NUM> carbon atoms and cyclic aliphatic hydrocarbon group having <NUM> to <NUM> carbon atoms. It is in particular preferred that R<NUM> and R<NUM> are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, iso-propyl, iso-butyl, iso-pentyl, tert. -butyl, tert. -amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

More preferably both R<NUM> and R<NUM> are the same, yet more preferably both R<NUM> and R<NUM> are an ethyl group.

Especially preferred external donors (ED) are the dicyclopentyl dimethoxy silane donor (D-donor) or the cyclohexylmethyl dimethoxy silane donor (C-Donor). In addition to the Ziegler-Natta catalyst (ZN-C) and the optional external donor (ED), a co-catalyst (Co) can be used. The co-catalyst (Co) is preferably a compound of group <NUM> of the periodic table (IUPAC), e.g. organo aluminum, such as an aluminum compound, like aluminum alkyl, aluminum halide or aluminum alkyl halide compound. Accordingly, in one specific embodiment the co-catalyst (Co) is a trialkylaluminum, like triethylaluminum (TEAL), dialkyl aluminum chloride or alkyl aluminum dichloride or mixtures thereof. In one specific embodiment the co-catalyst (Co) is triethylaluminum (TEAL).

Preferably, the ratio between the co-catalyst (Co) and the external donor (ED) [Co/ED] and/or the ratio between the co-catalyst (Co) and the transition metal (TM) [Co/TM] should be carefully chosen. Accordingly,.

According to the present invention, high-stiffness, high toughness propylene polymers are obtained when the catalyst is used in the presence of strongly coordinating external donors.

A process for the production of a heterophasic propylene copolymer (HECO) of the present invention is also an object of the present invention. Such a process comprising the following stages (i) and (ii) in any sequence:.

Such a process may preferably comprise the polymerization of propylene in the presence of.

The polypropylene composition according to the present invention can be obtained by (melt)-mixing the individual fractions, i.e. heterophasic propylene copolymer (HECO) (A) and copolymer (CPH) of propylene and <NUM>-hexene (B). During the melt mixing suitable additives can additionally be added. For mixing, a conventional compounding or blending apparatus, e.g. a Banbury mixer, a <NUM>-roll rubber mill, Buss-co-kneader, a single screw extruder with special mixing segments or a twin screw extruder may be used. The polymer composition recovered from the extruder is usually in the form of pellets.

In the blend for the polypropylene composition according to the present invention component (A) is present in an amount of from <NUM> to <NUM> wt% and component (B) is present in an amount of from <NUM> to <NUM> wt%.

Preferably component (A) is present in an amount of from <NUM> to <NUM> wt% and more preferably in an amount of from <NUM> to <NUM> wt%.

Thus component (B) is preferably present in an amount of from <NUM> to <NUM> wt% and more preferably in an amount of from <NUM> to <NUM> wt%.

The overall melt flow rate, i.e. the melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> of polypropylene composition is in a range of from <NUM> to <NUM>/<NUM>, preferably in a range of from <NUM> to <NUM>/<NUM>, more preferably in a range of from <NUM> to <NUM>/<NUM> and even more preferably in a range of from <NUM> to <NUM>/<NUM>.

It is appreciated that the inventive polypropylene composition preferably has a melting temperature Tm in the range of from <NUM> to <NUM>, more preferably in the range of from <NUM> to <NUM>, determined by differential scanning calorimetry (DSC) as described in the example section.

Additionally it is appreciated that the inventive polypropylene composition preferably has a crystallization temperature of more than <NUM>, more preferably in the range of from <NUM> to <NUM> and even more preferably in the range of from <NUM> to <NUM>, such as <NUM> to <NUM>, determined by differential scanning calorimetry (DSC) as described in the example section.

The polypropylene composition may preferably exhibit a flexural modulus, determined according to ISO <NUM>:<NUM>, in the range of from <NUM> to <NUM> MPa.

The polypropylene composition may preferably exhibit a Charpy notched impact strength at <NUM>, determined according to ISO <NUM>1eA, of at least <NUM> kJ/m<NUM>.

The polypropylene composition may preferably exhibit a puncture energy, determined according to the instrumented falling weight test according to ISO <NUM>-<NUM> at <NUM> as described herein, of at least <NUM> J.

The present invention is further concerned with a molded article comprising the heterophasic polypropylene composition of the present invention. The main end-uses for such molded articles are in packaging applications like thin-wall packaging for frozen or fresh food, adhesives, cosmetics or pharmaceuticals. Other end-uses are plastic containers and household articles, but also medical products, rigid packaging like detergent cartons, cup and plate boards for oven or microwave use or sterilizable food packaging, especially for deep freeze or refrigerator uses. The present invention provides the specific advantage that such articles may be produced with lower wall thicknesses without expense in the flowability of the polypropylene compositions and still having excellent impact and toughness properties. Furthermore, the stiffness/impact/toughness balance of the articles produced with the heterophasic polypropylene composition of the present invention is excellent.

The articles may be produced by any common conversion process suitable for thermoplastic polymers, like injection molding, extrusion blow molding, injection stretch blow molding or cast film extrusion.

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>.

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was further used to quantify the comonomer content and comonomer sequence distribution of the polymers. 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. Approximately <NUM> of material was dissolved in <NUM> of <NUM>,<NUM>-tetrachloroethane-d<NUM> (TCE-d<NUM>) along with chromium-(III)- acetylacetonate (Cr(acac)<NUM>) resulting in a <NUM> solution of relaxation agent in solvent (<NPL>). 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 and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE, using an optimised tip angle, <NUM> recycle delay and a 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. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at <NUM> ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present. Characteristic signals corresponding to the incorporation of ethylene were observed (<NPL>).

With characteristic signals corresponding to <NUM>,<NUM> erythro regio defects observed (as described in <NPL>, in <NPL>, and in <NPL>) the correction for the influence of the region-defects on determined properties was required. Characteristic signals corresponding to other types of regio defects were not observed.

The comonomer sequence distribution at the triad level was determined using the analysis method of Kakugo et al. This method was chosen for its robust nature and integration regions slightly adjusted to increase applicability to a wider range of comonomer contents.

The melt flow rates MFR<NUM> are measured with a load of <NUM> at <NUM> for propylene copolymers. The melt flow rate is the quantity of polymer in grams which the test apparatus standardised to ISO <NUM> extrudes within <NUM> minutes at a temperature of <NUM> under a load of <NUM>. The MFR<NUM> of a fraction (B) produced in the presence of a fraction (A) is calculated using the measured values of MFR<NUM> of fraction (A) and the mixture received after producing fraction (B) ("final"): <MAT>.

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

The intrinsic viscosity (iV) value increases with the molecular weight of a polymer. The iV values e.g. of the XCS were measured according to ISO <NUM>/<NUM> in decalin at <NUM>.

These properties were measured with a TA Instrument Q200 differential scanning calorimetry (DSC) on <NUM> to <NUM> samples. Crystallization temperature (Tc) and crystallization enthalpy (Hc) are determined from the cooling step, while melting temperature (Tm) and melting enthalpy (Hm) are determined from the second heating step, respectively, from the first heating step in case of the webs.

Charpy notched impact is measured according to ISO <NUM>/1eA at +<NUM> and at -<NUM> using an injection molded test specimen (<NUM> x <NUM> x <NUM>) as produced according to ISO <NUM>.

Tensile properties were determined according to ISO <NUM>-<NUM> on injection ISO multipurpose molded specimens prepared in accordance with EN ISO <NUM>-<NUM>.

Tensile modulus (in MPa) was determined according to ISO <NUM>-<NUM>. The measurement was conducted at <NUM> with an elongation rate of <NUM>/min.

The flexural modulus was determined in <NUM>-point-bending according to ISO <NUM> on 80x10x4 mm<NUM> test bars injection molded at <NUM> in line with EN ISO <NUM>-<NUM>.

Puncture energy (IPT) is determined in the instrumented falling weight test according to ISO <NUM>-<NUM> using injection molded plaques of 60x60x1 mm and a test speed of <NUM>/s, clamped, lubricated striker with <NUM> diameter. The reported puncture energy results from an integral of the failure energy curve measured at (60x60x1 mm).

<NUM> liters of <NUM>-ethylhexanol and <NUM> of propylene glycol butyl monoether (in a molar ratio <NUM>/<NUM>) were added to a <NUM> reactor. Then <NUM> liters of a <NUM> % solution in toluene of BEM (butyl ethyl magnesium) provided by Crompton GmbH were slowly added to the well stirred alcohol mixture. During the addition the temperature was kept at <NUM>. After addition the temperature of the reaction mixture was raised to <NUM> and mixing was continued at this temperature for <NUM> minutes. Finally after cooling to room temperature the obtained Mg-alkoxide was transferred to storage vessel.

<NUM> of Mg alkoxide prepared above was mixed with <NUM> bis(<NUM>-ethylhexyl) citraconate for <NUM>. After mixing the obtained Mg complex was used immediately in the preparation of catalyst component.

<NUM> titanium tetrachloride was placed in a <NUM> reactor equipped with a mechanical stirrer at <NUM>. Mixing speed was adjusted to <NUM> rpm. <NUM> of Mg-complex prepared above was added within <NUM> minutes keeping the temperature at <NUM>. <NUM> of Viscoplex <NUM>-<NUM> and <NUM> of a toluene solution with <NUM> Necadd <NUM> was added. Then <NUM> of heptane was added to form an emulsion. Mixing was continued for <NUM> minutes at <NUM>. Then the reactor temperature was raised to <NUM> within <NUM> minutes. The reaction mixture was stirred for further <NUM> minutes at <NUM>. Afterwards stirring was stopped and the reaction mixture was allowed to settle for <NUM> minutes at <NUM>.

The solid material was washed <NUM> times: Washings were made at <NUM> under stirring <NUM> with <NUM> rpm. After stirring was stopped the reaction mixture was allowed to settle for <NUM>-<NUM> minutes and followed by siphoning.

Wash <NUM>: Washing was made with a mixture of <NUM> of toluene and <NUM> donor.

Wash <NUM>: Washing was made with a mixture of <NUM> of TiCl<NUM> and <NUM> of donor.

Wash <NUM>: Washing was made with <NUM> toluene.

Wash <NUM>: Washing was made with <NUM> of heptane.

Wash <NUM>. Washing was made with <NUM> of heptane under <NUM> minutes stirring.

Afterwards stirring was stopped and the reaction mixture was allowed to settle for <NUM> minutes decreasing the temperature to <NUM> with subsequent siphoning, and followed by N<NUM> sparging for <NUM> minutes to yield an air sensitive powder.

Polymerization was conducted on a Borstar pilot plant with the set up of prepolymerizer loop, first gas phase reactor (GPR1) and second gas phase reactor (GPR2). The catalyst used were described above. The concentration of monomers in the reactor are adjusted by man skilled in the art to reach the desired polymer compostion, and the typical conditions are shown in Table <NUM>. The powder were mixed with <NUM> ppm of B225 and <NUM> ppm of calcium stearate in ZSK <NUM>, with melting temperature of <NUM>, throughput about <NUM>/h. The properties, e.g. MFR, Tm, XCS, etc, were measured and shown in Table <NUM>.

The CPH is a random ethylene-hexene copolymer with a C6 co-monomer content of about <NUM> wt. % and a MFR<NUM> of <NUM>/<NUM>. It was produced in a two stage polymerization process pilot plant with a metallocene catalyst as described in detail in <CIT> (metallocene complex MC1 with methylaluminoxane (MAO) and borate resulting in Catalyst <NUM> described in <CIT>) with the proviso that the surfactant is <NUM>,<NUM>,<NUM>,<NUM>-tetrafluoro-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>-heptafluoropropoxy)-<NUM>-propanol. The metallocene complex (MC1 in <CIT>) is prepared as described in <CIT> (metallocene E2 in <CIT>).

The random ethylene-hexene copolymer (CPH) was prepared in a sequential process comprising a loop reactor and a gas phase reactor. The reaction conditions are summarized in Table <NUM>.

Compounding of the inventive and comparative examples was done on a ZSK <NUM> twin screw extruder with <NUM> wt. % of the random ethylene-hexene copolymer. Mass tremperature: <NUM>. -% of Irganox B225 (<NUM>:<NUM>-blend of Irganox <NUM> and Irgafos <NUM>) of BASF AG, Germany), and <NUM> wt. -% calcium stearate were added during compounding.

Properties of the compositions are shown in Table <NUM> below.

Claim 1:
Polypropylene composition comprising a blend of
(A) <NUM> to <NUM> wt.%, based on the total amount of the composition, of a heterophasic propylene copolymer (HECO) comprising
(A-<NUM>) <NUM> to <NUM> wt.%, based on the total amount of the HECO, of a matrix (M) being a propylene homopolymer (H-PP) with a MFR<NUM>, determined at <NUM>, <NUM> according to ISO <NUM> of from <NUM> - <NUM>/<NUM>, and
(A-<NUM>) <NUM> to <NUM> wt.%, based on the total amount of the HECO, of an elastomeric propylene copolymer (EPC) dispersed in said matrix (M), said heterophasic propylene copolymer having an ethylene (C<NUM>) co-monomer content, determined from its xylene cold soluble (XCS) fraction according to ISO <NUM>; first edition, <NUM>-<NUM>-<NUM> at <NUM>, of from <NUM> to <NUM> wt.% and an intrinsic viscosity (IV) of the XCS fraction of from <NUM> to <NUM> dl/g, determined according to DIN ISO <NUM>/<NUM> in decalin at <NUM>, and
(B) <NUM> to <NUM> wt%, based on the total amount of the composition, of a copolymer (CPH) of propylene and <NUM>-hexene,
wherein the copolymer (CPH) of propylene and <NUM>-hexene has a hexene content in the range of from <NUM> to <NUM> wt.% and a MFR<NUM> determined at <NUM>, <NUM> according to ISO <NUM> in a range of from <NUM> to <NUM>/<NUM>, and
the copolymer (CPH) of propylene and <NUM>-hexene comprises
(i) a first random propylene copolymer (B-<NUM>) of propylene and <NUM>-hexene, and
(ii) a second random propylene copolymer (B-<NUM>) of propylene and <NUM>-hexene having a higher <NUM>-hexene content than the first random propylene copolymer (B-<NUM>),
wherein the polypropylene composition has a MFR<NUM> determined at <NUM>, <NUM> according to ISO <NUM> in the range of from <NUM> to <NUM>/<NUM>.