Patent Description:
Polyolefin compositions with high sterilization resistance and films comprising said compositions are gaining more and more interest, particularly in the field of packaging materials for medicals and food. The requirements for such films are high transparency, i.e. low haze, and high impact resistance. It is desirable that both properties are maintained after a step of heat sterilization which is, however, difficult to achieve for both properties together. By "sterilization resistance", a minimization of both the loss of transparency and the impact resistance after heat sterilization is meant. A further requirement for modem packaging applications for medicals and food is a certain softness of the material, meaning that the modulus should be as low as possible. The currently existing solution, i.e. heterophasic propylene copolymers (HECOs) or soft polypropylenes, are more or less suffering some challenges in one or the other respect.

<CIT> refers to a process of a soft heterophasic propylene copolymer with good optical properties in particular after sterilization for packaging applications, wherein the process shall not suffer from clogging which normally is caused when heterophasic propylene copolymers are produced containing high amounts of xylene cold solubles.

Therefore, a new solution is required. Moreover, the leachables content of the final composition is a topic if the crystallinity of the composition is too low.

Accordingly, it is an object of the present application to provide a polypropylene composition (C) comprising a heterophasic system with an optimized or improved balance between softness and optical properties.

The finding of the present invention is to provide a polypropylene composition (C) comprising a heterophasic propylene copolymer (RAHECO) and a propylene homopolymer (H-PP).

Accordingly, the present invention is directed to a polypropylene composition (C), comprising.

In one embodiment of the present invention, the polypropylene composition (C) has a melting temperature Tm above <NUM>.

In a further embodiment of the present invention, the polypropylene composition (C) has.

In another embodiment of the present invention, the ratio between the hexane soluble content C6 and the xylene soluble content XCS (C6/XCS) of the inventive polypropylene composition (C) is below <NUM>.

In one embodiment of the present invention, the polypropylene composition (C) has.

It is especially preferred that the difference between the haze after sterilization and the haze before sterilization measured according to ASTM D <NUM>-<NUM> on a <NUM> thick film is below <NUM> %.

In another embodiment of the present invention, the polypropylene composition (C) comprises.

based on the overall weight of the polypropylene composition (C).

In further embodiment of the present invention, the polypropylene composition (C) comprises.

In a further preferred embodiment of the present invention, the polypropylene composition (C) comprises.

In a further embodiment of the present invention, the comonomers of the random propylene copolymer (R-PP) and/or the comonomers of the elastomeric propylene copolymer (E) are ethylene and/or C<NUM> to C<NUM> α-olefins.

In still another embodiment of the present invention, the random propylene copolymer (R-PP) and the elastomeric propylene copolymer (E) form a heterophasic propylene copolymer (RAHECO), said heterophasic propylene copolymer (RAHECO) having.

It is especially preferred that the heterophasic propylene copolymer (RAHECO) comprises.

based on the overall weight of the heterophasic propylene copolymer (RAHECO).

In one embodiment of the present invention, the propylene homopolymer (H-PP) has a melt flow rate MFR (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>.

The present invention is further directed to a film comprising the polypropylene composition (C) as described above.

The present invention is also directed to a process for producing the polypropylene composition (C) as described above, comprising the steps of.

It is especially preferred that the first random propylene copolymer fraction (R-PP1), the random propylene copolymer (R-PP) and the elastomeric copolymer (E) have been polymerized in the presence of.

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

The inventive polypropylene composition (C) is especially featured by its specific optical and mechanical properties.

Accordingly, it is preferred that the polypropylene composition (C) has a flexural modulus measured on injection moulded specimens according to ISO <NUM> in the range of <NUM> to <NUM> MPa, preferably in the range of <NUM> to <NUM> MPa, like in the range of <NUM> to <NUM> MPa.

Further, it is preferred that the polypropylene composition (C) has a tensile modulus measured on <NUM> cast films in machine direction according to ISO <NUM>-<NUM> below <NUM> MPa, more preferably below <NUM> MPa, still more preferably below <NUM> MPa. A reasonable lower limit for said tensile modulus is <NUM> MPa.

With regard to the optical properties, it is preferred that the polypropylene composition (C) has a haze before sterilization according to ASTM D <NUM>-<NUM> measured on a <NUM> thick film below <NUM> %, more preferably below <NUM> %, still more preferably at most <NUM> %.

Furthermore, it is preferred that the polypropylene composition (C) has a haze after sterilization according to ASTM D <NUM>-<NUM> measured on a <NUM> thick film below <NUM> %, more preferably below <NUM> %, still more preferably at most <NUM> %.

Additionally or alternatively to the previous paragraphs, the difference between the haze after sterilization and the haze before sterilization measured according to ASTM D <NUM>-<NUM> on a <NUM> thick film is below <NUM> %, more preferably below <NUM> %, still more preferably below <NUM> %. Said difference can also reach negative values.

The polypropylene composition (C) according to this invention is featured by a moderate melt flow rate. Accordingly, the polypropylene composition (C) has a melt flow rate MFR<NUM> (<NUM> / <NUM>) measured according to ISO <NUM> of at least <NUM>/<NUM>, preferably in the range of <NUM> to <NUM>/<NUM>.

Preferably, the polypropylene composition (C) has a xylene soluble content (XCS) 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.

Preferably, the polypropylene composition (C) has an ethylene content of the xylene soluble fraction (XCS) of the polypropylene composition (C) of at least <NUM> mol-%, more preferably in the range of <NUM> to <NUM> mol-%, still more preferably in the range of <NUM> to <NUM> mol-%, still more preferably in the range of <NUM> to <NUM> mol-%.

Further, it is preferred that the polypropylene composition (C) has an intrinsic viscosity (IV) determined according to DIN ISO <NUM>/<NUM> (in Decalin at <NUM>) of the xylene soluble fraction (XCS) of at least <NUM> dl/g, more preferably in the range of <NUM> to <NUM> dl/g, still more preferably in the range of <NUM> to <NUM> dl/g.

Additionally, it is preferred that the intrinsic viscosity (IV) of the polypropylene composition (C) determined according to DIN ISO <NUM>/<NUM> (in Decalin at <NUM>) of the xylene insoluble fraction (XCI) is in the range of <NUM> to <NUM> dl/g, more preferably in the range of <NUM> to <NUM> dl/g, still more preferably in the range of <NUM> to <NUM> dl/g.

Further, it is preferred that the polypropylene composition (C) has a comonomer content of the xylene insoluble fraction (XCI) is in the range of <NUM> to <NUM> mol-%, more preferably in the range of <NUM> to <NUM> mol-%, still more preferably in the range of <NUM> to <NUM> mol-%.

The polypropylene composition (C) according to the present invention is also featured by a rather low amount of hexane solubles. Accordingly, the polypropylene composition (C) preferably has a hexane soluble content in the range of <NUM> to below <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. -%, still more preferably in the range of <NUM> to <NUM> wt.

Additionally to the previous paragraph, it is preferred that the ratio between the hexane soluble content C6 and the xylene soluble content XCS (C6/XCS) of the inventive polypropylene composition is below <NUM>, more preferably below <NUM>, still more preferably below <NUM>.

Preferably, it is desired that the polypropylene composition (C) is thermo mechanically stable. Accordingly, it is appreciated that the polypropylene composition (C) has a melting temperature above <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>.

Typically, the polypropylene composition (C) has a rather low crystallization temperature, i.e. of not more than <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>.

The polypropylene composition (C) comprises apart from propylene also comonomers. Preferably the polypropylene composition (C) comprises apart from propylene ethylene and/or C<NUM> to C<NUM> α-olefins. Accordingly, the term "polypropylene composition" according to this invention is understood as a polypropylene comprising, preferably consisting of, units derivable from.

Preferably, the polypropylene composition (C) has an ethylene content in the range of <NUM> to <NUM> mol. -%, more preferably in the range of <NUM> to <NUM> mol. -%, still more preferably in the range of <NUM> to <NUM> mol.

The inventive polypropylene composition (C) is a heterophasic system comprising a random propylene copolymer (R-PP) and a propylene homopolymer (H-PP) forming the matrix (M) and elastomeric propylene copolymer (E) dispersed in said matrix (M). Thus the matrix (M) contains (finely) dispersed inclusions being not part of the matrix (M) and said inclusions contain the elastomeric propylene copolymer (E). The term inclusion indicates that the matrix (M) and the inclusion form different phases as defined below.

It is preferred that the polypropylene composition (C) comprises, more preferably consists of, <NUM> to <NUM> wt. -% of the matrix (M), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -% and <NUM> to <NUM> wt. -% of the elastomeric propylene copolymer (E), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%, based on the overall weight of the polypropylene composition (C).

As outlined above, the matrix of the polypropylene composition (C) comprises a random propylene copolymer (R-PP) and a propylene homopolymer (H-PP).

In particular, it is preferred that the polypropylene composition (C) comprises, more preferably consists of, <NUM> to <NUM> wt. -% of the random propylene copolymer (R-PP), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%, and <NUM> to <NUM> wt. -% of the propylene homopolymer (H-PP), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%, and <NUM> to <NUM> wt. -% of the elastomeric propylene copolymer (E), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%, based on the overall weight of the polypropylene composition (C).

The polypropylene composition (C) of the present invention may include additives (AD). Accordingly, it is preferred that the polypropylene composition (C) comprises, more preferably consists of, <NUM> to <NUM> wt. -% of the random propylene copolymer (R-PP), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%, and <NUM> to <NUM> wt. -% of the propylene homopolymer (H-PP), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%, and <NUM> to <NUM> wt. -% of the elastomeric propylene copolymer (E), more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -%,and <NUM> to <NUM> wt. -%, preferably <NUM> to <NUM> wt. -% of additives (AD), based on the overall weight of the polypropylene composition (C). The additives (AD) are described in more detail below.

Preferably the polypropylene composition (C) of the invention does not comprise (a) further polymer(s) different to the random propylene copolymer (R-PP), the propylene homopolymer (H-PP) and the elastomeric propylene copolymer (E) in an amount exceeding <NUM> wt. -%, preferably in an amount exceeding <NUM> wt. -%, more preferably in an amount exceeding <NUM> wt. -%, based on the overall weight of the polypropylene composition (C).

Preferably, the polypropylene composition (C) is obtained by a sequential polymerization process wherein at least two, like three, reactors are connected in series. For example, said process comprises the steps of.

Alternatively, the polypropylene composition (C) is obtained by melt blending a heterophasic propylene copolymer (RAHECO) with the propylene homopolymer (H-PP), said heterophasic propylene copolymer (RAHECO) comprising the random propylene copolymer (R-PP) and the elastomeric propylene copolymer (E). Melt blending of said heterophasic propylene copolymer (RAHECO) with the propylene homopolymer (H-PP) results in a heterophasic system wherein the elastomeric propylene copolymer (E) is dispersed within the random copolymer (R-PP) and the propylene homopolymer (H-PP), i.e. a heterophasic system wherein the random copolymer (R-PP) and the propylene homopolymer (H-PP) form the matrix.

It is especially preferred that the polypropylene composition (C) is obtained by melt blending a heterophasic propylene copolymer (RAHECO) as defined above with the propylene homopolymer (H-PP).

In the following, the heterophasic propylene copolymer (RAHECO) and the propylene homopolymer (H-PP) are described in more detail.

The inventive polypropylene composition (C) comprises a heterophasic propylene copolymer (RAHECO).

The heterophasic propylene copolymer (RAHECO) according to this invention comprises a matrix (M) being a random propylene copolymer (R-PP) and dispersed therein an elastomeric propylene copolymer (E). Thus the matrix (M) contains (finely) dispersed inclusions being not part of the matrix (M) and said inclusions contain the elastomeric propylene copolymer (E). The term inclusion indicates that the matrix (M) and the inclusion form different phases within the heterophasic propylene copolymer (RAHECO). The presence of second phases or the so called inclusions are 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.

Preferably, the heterophasic propylene copolymer (RAHECO) according to this invention comprises as polymer components only the random propylene copolymer (R-PP) and the elastomeric propylene copolymer (E). In other words, the heterophasic propylene copolymer (RAHECO) may contain further additives but no other polymer in an amount exceeding <NUM> wt. -%, more preferably exceeding <NUM> wt. -%, like exceeding <NUM> wt. -%, based on the total heterophasic propylene copolymer (RAHECO). One additional polymer which may be present in such low amounts is a polyethylene which is a by-reaction product obtained by the preparation of the heterophasic propylene copolymer (RAHECO). Accordingly, it is in particular appreciated that the instant heterophasic propylene copolymer (RAHECO) contains only the random propylene copolymer (R-PP), the elastomeric propylene copolymer (E) and optionally polyethylene in amounts as mentioned in this paragraph.

The heterophasic propylene copolymer (RAHECO) preferably applied according to this invention is featured by a rather low melt flow rate. Accordingly, the heterophasic propylene copolymer (RAHECO), preferably has a melt flow rate MFR<NUM> (<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>. Preferably the melt flow rate MFR<NUM> (<NUM>) indicated in this paragraph is the melt flow rate MFR<NUM> (<NUM>) after visbreaking (see below).

Preferably, it is desired that the heterophasic propylene copolymer (RAHECO) is thermo mechanically stable. Accordingly, it is appreciated that the heterophasic propylene copolymer (RAHECO) has a melting temperature of at least <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>.

Typically, the heterophasic propylene copolymer (RAHECO) has a rather low crystallization temperature, i.e. of not more than <NUM>, more preferably in the range of <NUM> to <NUM>, still more preferably in the range of <NUM> to <NUM>.

The heterophasic propylene copolymer (RAHECO) comprises apart from propylene also comonomers. Preferably the heterophasic propylene copolymer (RAHECO) comprises apart from propylene ethylene and/or C<NUM> to C<NUM> α-olefins. Accordingly, the term "propylene copolymer" according to this invention is understood as a polypropylene comprising, preferably consisting of, units derivable from.

Thus, the heterophasic propylene copolymer (RAHECO), i.e. the random propylene copolymer (R-PP) as well as the elastomeric propylene copolymer (E), such as the first elastomeric propylene copolymer fraction (E1) and the second elastomeric propylene copolymer fraction (E2), comprises monomers copolymerizable with propylene, for example comonomers such as ethylene and/or C<NUM> to C<NUM> α-olefins, in particular ethylene and/or C<NUM> to C<NUM> α-olefins, e.g. <NUM>-butene and/or <NUM>-hexene. Preferably, the heterophasic propylene copolymer (RAHECO) according to this invention comprises, especially consists of, monomers copolymerizable with propylene from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. More specifically, the heterophasic propylene copolymer (RAHECO) of this invention comprises - apart from propylene - units derivable from ethylene and/or <NUM>-butene. In a preferred embodiment, the heterophasic propylene copolymer (RAHECO) according to this invention comprises units derivable from ethylene and propylene only. Still more preferably the random propylene copolymer (R-PP) as well as the elastomeric propylene copolymer (E), i.e. the first elastomeric propylene copolymer fraction (E1) and the second elastomeric propylene copolymer fraction (E2) of the heterophasic propylene copolymer (RAHECO) contain the same comonomers, like ethylene.

Accordingly, the elastomeric propylene copolymer (E) is preferably an ethylene propylene rubber (EPR), whereas the random propylene copolymer (R-PP) is a random ethylene propylene copolymer (R-PP).

Additionally, it is appreciated that the heterophasic propylene copolymer (RAHECO) preferably has a moderate total comonomer content, preferably ethylene content, which contributes to the softness of the material. Thus, it is preferred that the comonomer content of the heterophasic propylene copolymer (RAHECO) is in the range from <NUM> to <NUM> mol-%, preferably in the range from <NUM> to <NUM> mol-%, more preferably in the range from <NUM> to <NUM> mol-%.

The xylene cold soluble (XCS) fraction measured according to according ISO <NUM> (<NUM>) of the heterophasic propylene copolymer (RAHECO) is in the range of <NUM> to <NUM> wt. -%, preferably in the range from <NUM> to <NUM> wt. -%, more preferably in the range from <NUM> to <NUM> wt. -%, still more preferably in the range from <NUM> to <NUM> wt.

Further it is appreciated that the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (RAHECO) is specified by its intrinsic viscosity. A low intrinsic viscosity (IV) value reflects a low weight average molecular weight. For the present invention it is appreciated that the xylene cold soluble fraction (XCS) of the heterophasic propylene copolymer (RAHECO) has an intrinsic viscosity (IV) measured according to ISO <NUM>/<NUM> (at <NUM> in decalin) in the range of <NUM> to <NUM> dl/g, preferably in the range of <NUM> to <NUM> dl/g, more preferably in the range of <NUM> to <NUM> dl/g.

Additionally, it is preferred that the comonomer content, i.e. ethylene content, of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (RAHECO) is below <NUM> mol-%, preferably in the range of <NUM> to <NUM> mol-%, more preferably in the range of <NUM> to <NUM> mol. -%, yet more preferably in the range of <NUM> to <NUM> mol. The comonomers present in the xylene cold soluble (XCS) fraction are those defined above for the random propylene copolymer (R-PP) and the elastomeric propylene copolymer (E), respectively. In one preferred embodiment the comonomer is ethylene only.

The heterophasic propylene copolymer (RAHECO) can be further defined by its individual components, i.e. the random propylene copolymer (R-PP) and the elastomeric propylene copolymer (E).

The random propylene copolymer (R-PP) comprises monomers copolymerizable with propylene, for example comonomers such as ethylene and/or C<NUM> to C<NUM> α-olefins, in particular ethylene and/or C<NUM> to C<NUM> α-olefins, e.g. <NUM>-butene and/or <NUM>-hexene. Preferably the random propylene copolymer (R-PP) according to this invention comprises, especially consists of, monomers copolymerizable with propylene from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. More specifically the random propylene copolymer (R-PP) of this invention comprises - apart from propylene - units derivable from ethylene and/or <NUM>-butene. In a preferred embodiment the random propylene copolymer (R-PP) comprises units derivable from ethylene and propylene only.

The random propylene copolymer (R-PP) according to this invention has a preferable melt flow rate MFR<NUM> (<NUM>/<NUM>) before visbreaking measured 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>.

As mentioned above the heterophasic propylene copolymer (RAHECO) is preferably featured by a moderate comonomer content. Accordingly, the preferred comonomer content of the random propylene copolymer (R-PP) is in the range of <NUM> to <NUM> mol-%, yet more preferably in the range of <NUM> to <NUM> mol-%, still more preferably in the range of <NUM> to <NUM> mol-%.

The term "random" indicates that the comonomers of the random propylene copolymer (R-PP) are randomly distributed within the propylene copolymer. The term random is understood according to IUPAC (Glossary of basic terms in polymer science; IUPAC recommendations <NUM>).

The random propylene copolymer (R-PP) preferably comprises at least two polymer fractions, like two or three polymer fractions, all of them are propylene copolymers. Even more preferred the random propylene copolymer (R-PP) comprises, preferably consists of, a first propylene copolymer fraction (R-PP1) and a second propylene copolymer fraction (R-PP2).

Concerning the comonomers used for the first propylene copolymer fraction (R-PP1) and second propylene copolymer fraction (R-PP2) reference is made to the comonomers of the random propylene copolymer (R-PP). Preferably the first propylene copolymer fraction (R-PP1) and the second propylene copolymer fraction (R-PP2) contain the same comonomers, like ethylene.

The heterophasic propylene copolymer (RAHECO) preferably comprises <NUM> to <NUM> wt. -%, more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -% of the random propylene copolymer (R-PP), based on the total weight of the heterophasic propylene copolymer (RAHECO).

Additionally, the heterophasic propylene copolymer (RAHECO) preferably comprises <NUM> to <NUM> wt. -%, more preferably <NUM> to <NUM> wt. -%, still more preferably <NUM> to <NUM> wt. -% of the elastomeric propylene copolymer (E), based on the total weight of the heterophasic propylene copolymer (RAHECO).

Thus, it is appreciated that the heterophasic propylene copolymer (RAHECO) preferably comprises, more preferably consists of, <NUM> to <NUM> wt. -%, preferably <NUM> to <NUM> wt. -%, more preferably <NUM> to <NUM> wt. -% of the random propylene copolymer (R-PP) and <NUM> to <NUM> wt. -%, preferably <NUM> to <NUM> wt. -%, more preferably <NUM> to <NUM> wt. -% of the elastomeric propylene copolymer (E), based on the total weight of the heterophasic propylene copolymer (RAHECO).

Accordingly, a further component of the heterophasic propylene copolymer (RAHECO) is the elastomeric propylene copolymer (E) dispersed in the matrix (M). Concerning the comonomers used in the elastomeric propylene copolymer (E) it is referred to the information provided for the heterophasic propylene copolymer (RAHECO). Accordingly, the elastomeric propylene copolymer (E) comprises monomers copolymerizable with propylene, for example comonomers such as ethylene and/or C<NUM> to C<NUM> α-olefins, in particular ethylene and/or C<NUM> to C<NUM> α-olefins, e.g. <NUM>-butene and/or <NUM>-hexene. Preferably, the elastomeric propylene copolymer (E) comprises, especially consists of, monomers copolymerizable with propylene from the group consisting of ethylene, <NUM>-butene and <NUM>-hexene. More specifically, the elastomeric propylene copolymer (E) comprises - apart from propylene - units derivable from ethylene and/or <NUM>-butene. Thus, in an especially preferred embodiment the elastomeric propylene copolymer (E) comprises units derivable from ethylene and propylene only.

The comonomer content of the elastomeric propylene copolymer (E) preferably is in the range of <NUM> to <NUM> mol-%, more preferably in the range of <NUM> to <NUM> mol-%, still more preferably in the range of <NUM> to <NUM> mol-%.

As indicated above, the random propylene copolymer (R-PP) preferably comprises at least two polymer fractions, like two or three polymer fractions, all of them are propylene copolymers. Even more preferred the random propylene copolymer (R-PP) comprises, preferably consists of, a first propylene copolymer fraction (R-PP1) and a second propylene copolymer fraction (R-PP2). It is preferred that the first propylene copolymer fraction (R-PP1) is the comonomer lean fraction whereas the second propylene copolymer fraction (R-PP2) is the comonomer rich fraction.

Preferably, the comonomer contents of the random propylene copolymer (R-PP) and the first propylene copolymer fraction (R-PP1) fulfil inequation (II), more preferably inequation (IIa), still more preferably inequation (IIb), <MAT> <MAT> <MAT> wherein Co(RPP) is the comonomer content [mol. -%] of the random propylene copolymer (R-PP) and Co(RPP1) is the comonomer content [mol. -%] of the first propylene copolymer fraction (R-PP1).

Preferably, the first propylene copolymer fraction (R-PP1) and the second propylene copolymer fraction (R-PP2) differ in the comonomer content.

Preferably one of the propylene copolymer fractions (R-PP1) and (R-PP2) of the random propylene copolymer (R-PP) is the comonomer lean fraction and the other fraction is the comonomer rich fraction, wherein further the lean fraction and the rich fraction fulfil inequation (III), more preferably inequation (IIIa), still more preferably inequation (IIIb), <MAT> <MAT> <MAT> wherein Co (lean) is the comonomer content [mol-%] of the random propylene copolymer fraction with the lower comonomer content and Co (rich) is the comonomer content [mol-%] of the random propylene copolymer fraction with the higher comonomer content.

Preferably, the first propylene copolymer fraction (R-PP1) is the random copolymer fraction with the lower comonomer content and the second propylene copolymer fraction (R-PP2) is the random copolymer fraction with the higher comonomer content.

Accordingly, it is preferred that the first propylene copolymer fraction (R-PP1) has a comonomer content in the range of <NUM> to <NUM> mol. -%, more preferably in the range of <NUM> to <NUM> mol. -%, still more preferably in the range of <NUM> to <NUM> mol. -% and/or that the second propylene copolymer fraction has a comonomer content in the range of <NUM> to <NUM> mol. -%, more preferably in the range of <NUM> to <NUM> mol. -%, still more preferably in the range of <NUM> to <NUM> mol. -%, based on the overall fractions (R-PP1) and (R-PP2), respectively.

In addition or alternatively to inequation (III) one of the propylene copolymer fractions (R-PP1) and (R-PP2) of the random propylene copolymer (R-PP) is the low melt flow rate MFR<NUM> (<NUM> / <NUM>) fraction and the other fraction is the high melt flow rate MFR<NUM> (<NUM> / <NUM>) fraction, wherein further the low flow fraction and the high flow fraction fulfil inequation (IV), more preferably inequation (IVa), still more preferably inequation (IVb), <MAT> <MAT> <MAT> wherein MFR (high) is the melt flow rate MFR<NUM> (<NUM> / <NUM>) [g/<NUM>] before visbreaking of the random propylene copolymer fraction with the higher melt flow rate MFR<NUM> (<NUM> / <NUM>) and MFR (low) is the melt flow rate MFR<NUM> (<NUM> / <NUM>) [g/<NUM>] before visbreaking of the random propylene copolymer fraction with the lower melt flow rate MFR<NUM> (<NUM> / <NUM>).

Preferably, the first propylene copolymer fraction (R-PP1) is the random copolymer fraction with the higher melt flow rate MFR<NUM> (<NUM> / <NUM>) and the second propylene copolymer fraction (R-PP2) is the random copolymer fraction with the lower melt flow rate MFR<NUM> (<NUM> / <NUM>).

Accordingly, it is preferred that the first propylene copolymer fraction (R-PP1) has a melt flow rate MFR<NUM> (<NUM> / <NUM>) before visbreaking 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> and/or that the second propylene copolymer fraction (R-PP2) has a melt flow rate MFR<NUM> (<NUM> / <NUM>) before visbreaking 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>.

The heterophasic propylene copolymer (RAHECO) as defined in the instant invention may contain up to <NUM> wt. -% additives, like nucleating agents and antioxidants, as well as slip agents and antiblocking agents. Preferably the additive content (without α-nucleating agents) is below <NUM> wt. -%, like below <NUM> wt.

Further, the weight ratio between the first propylene copolymer fraction (R-PP1) and second propylene copolymer fraction (R-PP2) preferably is <NUM>:<NUM> to <NUM>:<NUM>, more preferably <NUM>:<NUM> to <NUM>:<NUM>, still more preferably <NUM>:<NUM> to <NUM>:<NUM>.

In one embodiment of the present invention, the heterophasic propylene copolymer (RAHECO) has been visbroken.

The visbroken heterophasic propylene copolymer (RAHECO) preferably has a higher melt flow rate than the non-visbroken heterophasic propylene copolymer (RAHECO).

Accordingly, the heterophasic propylene copolymer (RAHECO) before visbreaking preferably has a melt flow rate MFR<NUM> (<NUM>) in the range of <NUM> to <NUM>/<NUM>. For example, the melt flow rate (<NUM>/<NUM>) of the heterophasic propylene copolymer (RAHECO) before visbreaking is from <NUM> to <NUM>/<NUM>, like from <NUM> to <NUM>/<NUM>.

In one embodiment of the present invention, the heterophasic propylene copolymer (RAHECO) has been visbroken with a visbreaking ratio (VR) as defined by equation (V) <MAT> wherein.

Preferred mixing devices suited for visbreaking are discontinuous and continuous kneaders, twin screw extruders and single screw extruders with special mixing sections and co-kneaders.

By visbreaking the heterophasic propylene copolymer (RAHECO) with heat or at more controlled conditions with peroxides, the molar mass distribution (MWD) becomes narrower because the long molecular chains are more easily broken up or scissored and the molar mass M, will decrease, corresponding to an MFR<NUM> increase. The MFR<NUM> increases with increase in the amount of peroxide which is used.

Such visbreaking may be carried out in any known manner, like by using a peroxide visbreaking agent. Typical visbreaking agents are <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-bis(tert. -butyl-peroxy)hexane (DHBP) (for instance sold under the tradenames Luperox <NUM> and Trigonox <NUM>), <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-bis(tert. -butyl-peroxy)hexyne-<NUM> (DYBP) (for instance sold under the tradenames Luperox <NUM> and Trigonox <NUM>), dicumyl-peroxide (DCUP) (for instance sold under the tradenames Luperox DC and Perkadox BC), di-tert. -butyl-peroxide (DTBP) (for instance sold under the tradenames Trigonox B and Luperox Di), tert. -butyl-cumyl-peroxide (BCUP) (for instance sold under the tradenames Trigonox T and Luperox <NUM>) and bis (tert. -butylperoxy-isopropyl)benzene (DIPP) (for instance sold under the tradenames Perkadox <NUM> and Luperox DC). Suitable amounts of peroxide to be employed in accordance with the present invention are in principle known to the skilled person and can easily be calculated on the basis of the amount of heterophasic propylene copolymer (RAHECO) to be subjected to visbreaking, the MFR<NUM> (<NUM>/<NUM>) value of the heterophasic propylene copolymer (RAHECO) to be subjected to visbreaking and the desired target MFR<NUM> (<NUM>/<NUM>) of the product to be obtained. Accordingly, typical amounts of peroxide visbreaking agent are from <NUM> to <NUM> wt. -%, more preferably from <NUM> to <NUM> wt. -%, based on the total amount of heterophasic propylene copolymer (RAHECO) employed.

Typically, visbreaking in accordance with the present invention is carried out in an extruder, so that under the suitable conditions, an increase of melt flow rate is obtained. During visbreaking, higher molar mass chains of the starting product are broken statistically more frequently than lower molar mass molecules, resulting as indicated above in an overall decrease of the average molecular weight and an increase in melt flow rate.

The inventive heterophasic propylene copolymer (RAHECO) is preferably obtained by visbreaking the heterophasic propylene copolymer (RAHECO), preferably visbreaking by the use of peroxide.

More precisely, the inventive heterophasic propylene copolymer (RAHECO) may be obtained by visbreaking the heterophasic propylene copolymer (RAHECO), preferably by the use of peroxide as mentioned above, in an extruder.

After visbreaking the heterophasic propylene copolymer (RAHECO) according to this invention is preferably in the form of pellets or granules. The instant heterophasic propylene copolymer (RAHECO) is preferably used in pellet or granule form for the preparation of the film.

The heterophasic propylene copolymer (RAHECO) is preferably produced in a multistage process comprising at least two reactors connected in series a heterophasic propylene copolymer (RAHECO) comprising a matrix (M) being a random propylene copolymer (PP) and an elastomeric propylene copolymer (E) dispersed in said matrix (M).

Preferably the heterophasic propylene copolymer (RAHECO) is obtained by a sequential polymerization process comprising the steps of.

For preferred embodiments of the random heterophasic propylene copolymer (RAHECO), the random propylene copolymer (R-PP), the first propylene copolymer fraction (R-PP1), the second propylene copolymer fraction (R-PP2) and the elastomeric copolymer (E), reference is made to the definitions given above.

The term "sequential polymerization process" indicates that the random heterophasic propylene copolymer (RAHECO) is produced in at least two, like three, reactors connected in series. Accordingly, the present process comprises at least a first reactor, a second reactor, and optionally a third reactor. The term "polymerization process" shall indicate that the main polymerization takes place. Thus in case the process consists of three polymerization reactors, this definition does not exclude the option that the overall process comprises for instance a pre-polymerization step in a pre-polymerization reactor. The term "consist of" is only a closing formulation in view of the main polymerization process.

The first reactor is preferably a slurry reactor 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 is preferably a (bulk) loop reactor.

The second reactor and the third reactor are preferably gas phase reactors. Such gas phase reactors can be any mechanically mixed or fluid bed reactors. Preferably the gas phase reactors 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 reactor is a slurry reactor, like loop reactor, whereas the second reactor and the third reactor (R3) are gas phase reactors (GPR). Accordingly, for the instant process at least three, preferably three polymerization reactors, namely a slurry reactor, like loop reactor, a first gas phase reactor and a second gas phase reactor are connected in series are used. If needed prior to the slurry reactor a pre-polymerization reactor is placed.

A preferred multistage 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> or in <CIT>.

A further suitable slurry-gas phase process is the Spheripol® process of Basell.

Preferably, in the instant process for producing the heterophasic propylene copolymer (RAHECO) as defined above the conditions for the first reactor, i.e. the slurry reactor, like a loop reactor, may be as follows:.

Subsequently, the reaction mixture of the first reactor is transferred to the second reactor, i.e. gas phase reactor, where the conditions are preferably as follows:.

The condition in the third reactor is similar to the second reactor.

The residence time can vary in the three reactor zones.

In one embodiment of the process for producing the heterophasic propylene copolymer (RAHECO) the residence time in bulk reactor, e.g. loop is in the range <NUM> to <NUM> hours, e.g. <NUM> to <NUM> hours and the residence time in gas phase reactor will generally be <NUM> to <NUM> hours, like <NUM> to <NUM> hours.

If desired, the polymerization may be effected in a known manner under supercritical conditions in the first reactor, i.e. in the slurry reactor, like in the loop reactor, and/or as a condensed mode in the gas phase reactors.

Preferably, the process comprises also a prepolymerization with the catalyst system, as described in detail below, comprising a Ziegler-Natta procatalyst, an external donor and optionally a cocatalyst.

In a preferred embodiment, the prepolymerization 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 prepolymerization 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 prepolymerization 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.

The catalyst components are preferably all introduced to the prepolymerization step. However, where the solid catalyst component (i) and the cocatalyst (ii) can be fed separately it is possible that only a part of the cocatalyst 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 cocatalyst 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 invention the heterophasic propylene copolymer (RAHECO) is obtained by a multistage polymerization process, as described above, in the presence of a catalyst system.

As pointed out above in the specific process for the preparation of the heterophasic propylene copolymer (RAHECO) as defined above, a specific Ziegler-Natta catalyst (ZN-C) must be used. Accordingly, the Ziegler-Natta catalyst (ZN-C) will be now described in more detail.

The heterophasic propylene copolymer (RAHECO) applied according to this invention is preferably produced in the presence of.

The catalyst used in the present invention is a solid Ziegler-Natta catalyst (ZN-C), which comprises compounds (TC) of a transition metal of Group <NUM> to <NUM> of IUPAC, like titanium, a Group <NUM> metal compound (MC), like a magnesium, and an internal donor (ID) being a non-phthalic compound, preferably a non-phthalic acid ester, still more preferably being a diester of non-phthalic dicarboxylic acids as described in more detail below. Thus, the catalyst is fully free of undesired phthalic compounds. Further, the solid catalyst is free of any external support material, like silica or MgCl<NUM>, but the catalyst is selfsupported.

The Ziegler-Natta catalyst (ZN-C) can be further defined by the way as obtained. Accordingly, the Ziegler-Natta catalyst (ZN-C) is preferably obtained by a process comprising the steps of.

and adding a non-phthalic internal electron donor (ID) at any step prior to step c).

The internal donor (ID) or precursor thereof is added preferably to the solution of step a).

According to the procedure above the Ziegler-Natta catalyst (ZN-C) can be obtained via precipitation method or via emulsion (liquid/liquid two-phase system) - solidification method depending on the physical conditions, especially temperature used in steps b) and c).

In both methods (precipitation or emulsion-solidification) the catalyst chemistry is the same.

In precipitation method combination of the solution of step a) with at least one transition metal compound (TC) in step b) is carried out and the whole reaction mixture is kept at least at <NUM>, more preferably in the temperature range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>, to secure full precipitation of the catalyst component in form of a solid particles (step c).

In emulsion - solidification method in step b) the solution of step a) is typically added to the at least one transition metal compound (TC) at a lower temperature, such as from -<NUM> to below <NUM>, preferably from -<NUM> to <NUM>. During agitation of the emulsion the temperature is typically kept at -<NUM> to below <NUM>, preferably from -<NUM> to <NUM>. Droplets of the dispersed phase of the emulsion form the active catalyst composition. Solidification (step c) of the droplets is suitably carried out by heating the emulsion to a temperature of <NUM> to <NUM>, preferably to <NUM> to <NUM>.

The catalyst prepared by emulsion - solidification method is preferably used in the present invention.

In a preferred embodiment in step a) the solution of a<NUM>) or a<NUM>) are used, i.e. a solution of (Ax') or a solution of a mixture of (Ax) and (Bx).

Preferably the Group <NUM> metal (MC) is magnesium.

The magnesium alkoxy compounds (Ax), (Ax') and (Bx) can be prepared in situ in the first step of the catalyst preparation process, step a), by reacting the magnesium compound with the alcohol(s) as described above, or said magnesium alkoxy compounds can be separately prepared magnesium alkoxy compounds or they can be even commercially available as ready magnesium alkoxy compounds and used as such in the catalyst preparation process of the invention.

Illustrative examples of alcohols (A) are monoethers of dihydric alcohols (glycol monoethers). Preferred alcohols (A) are C<NUM> to C<NUM> glycol monoethers, wherein the ether moieties comprise from <NUM> to <NUM> carbon atoms, preferably from <NUM> to <NUM> carbon atoms. Preferred examples are <NUM>-(<NUM>-ethylhexyloxy)ethanol, <NUM>-butyloxy ethanol, <NUM>-hexyloxy ethanol and <NUM>,<NUM>-propylene-glycol-monobutyl ether, <NUM>-butoxy-<NUM>-propanol, with <NUM>-(<NUM>-ethylhexyloxy)ethanol and <NUM>,<NUM>-propylene-glycol-monobutyl ether, <NUM>-butoxy-<NUM>-propanol being particularly preferred.

Illustrative monohydric alcohols (B) are of formula ROH, with R being straight-chain or branched C<NUM>-C<NUM> alkyl residue. The most preferred monohydric alcohol is <NUM>-ethyl-<NUM>-hexanol or octanol.

Preferably a mixture of Mg alkoxy compounds (Ax) and (Bx) or mixture of alcohols (A) and (B), respectively, are used and employed in a mole ratio of Bx:Ax or B:A from <NUM>:<NUM> to <NUM>:<NUM>, more preferably <NUM>:<NUM> to <NUM>:<NUM>.

Magnesium alkoxy compound may be a reaction product of alcohol(s), as defined above, and a magnesium compound selected from dialkyl magnesiums, alkyl magnesium alkoxides, magnesium dialkoxides, alkoxy magnesium halides and alkyl magnesium halides. Alkyl groups can be a similar or different C<NUM>-C<NUM> alkyl, preferably C<NUM>-C<NUM> alkyl. Typical alkyl-alkoxy magnesium compounds, when used, are ethyl magnesium butoxide, butyl magnesium pentoxide, octyl magnesium butoxide and octyl magnesium octoxide. Preferably the dialkyl magnesiums are used. Most preferred dialkyl magnesiums are butyl octyl magnesium or butyl ethyl magnesium.

It is also possible that magnesium compound can react in addition to the alcohol (A) and alcohol (B) also with a polyhydric alcohol (C) of formula R" (OH)m to obtain said magnesium alkoxide compounds. Preferred polyhydric alcohols, if used, are alcohols, wherein R" is a straight-chain, cyclic or branched C<NUM> to C<NUM> hydrocarbon residue, and m is an integer of <NUM> to <NUM>.

The magnesium alkoxy compounds of step a) are thus selected from the group consisting of magnesium dialkoxides, diaryloxy magnesiums, alkyloxy magnesium halides, aryloxy magnesium halides, alkyl magnesium alkoxides, aryl magnesium alkoxides and alkyl magnesium aryloxides. In addition a mixture of magnesium dihalide and a magnesium dialkoxide can be used.

The solvents to be employed for the preparation of the present catalyst may be selected among aromatic and aliphatic straight chain, branched and cyclic hydrocarbons with <NUM> to <NUM> carbon atoms, more preferably <NUM> to <NUM> carbon atoms, or mixtures thereof. Suitable solvents include benzene, toluene, cumene, xylene, pentane, hexane, heptane, octane and nonane. Hexanes and pentanes are particular preferred.

Mg compound is typically provided as a <NUM> to <NUM> wt-% solution in a solvent as indicated above. Typical commercially available Mg compound, especially dialkyl magnesium solutions are <NUM> - <NUM> wt-% solutions in toluene or heptanes.

The reaction for the preparation of the magnesium alkoxy compound may be carried out at a temperature of <NUM>° to <NUM>. Most suitable temperature is selected depending on the Mg compound and alcohol(s) used.

The transition metal compound of Group <NUM> to <NUM> is preferably a titanium comound, most preferably a titanium halide, like TiCl<NUM>.

The internal donor (ID) used in the preparation of the catalyst used in the present invention is preferably selected from (di)esters of non-phthalic carboxylic (di)acids, <NUM>,<NUM>-diethers, derivatives and mixtures thereof. Especially preferred donors are diesters of mono-unsaturated dicarboxylic acids, in particular esters belonging to a group comprising malonates, maleates, succinates, citraconates, glutarates, cyclohexene-<NUM>,<NUM>-dicarboxylates and benzoates, and any derivatives and/or mixtures thereof. Preferred examples are e.g. substituted maleates and citraconates, most preferably citraconates.

In emulsion method, the two phase liquid-liquid system may be formed by simple stirring and optionally adding (further) solvent(s) and additives, such as the turbulence minimizing agent (TMA) and/or the emulsifying agents and/or emulsion stabilizers, like surfactants, which are used in a manner known in the art for facilitating the formation of and/or stabilize the emulsion. Preferably, surfactants are acrylic or methacrylic polymers. Particular preferred are unbranched C<NUM> to C<NUM> (meth)acrylates such as poly(hexadecyl)-methacrylate and poly(octadecyl)-methacrylate and mixtures thereof. Turbulence minimizing agent (TMA), if used, is preferably selected from α-olefin polymers of α-olefin monomers with <NUM> to <NUM> carbon atoms, like polyoctene, polynonene, polydecene, polyundecene or polydodecene or mixtures thereof. Most preferable it is polydecene.

The solid particulate product obtained by precipitation or emulsion - solidification method may be washed at least once, preferably at least twice, most preferably at least three times with an aromatic and/or aliphatic hydrocarbons, preferably with toluene, heptane or pentane. The catalyst can further be dried, as by evaporation or flushing with nitrogen, or it can be slurried to an oily liquid without any drying step.

The finally obtained Ziegler-Natta catalyst is desirably in the form of particles having generally an average particle size range of <NUM> to <NUM>, preferably <NUM> to <NUM>. Particles are compact with low porosity and have surface area below <NUM>/m<NUM>, more preferably below <NUM>/m<NUM>. Typically, the amount of Ti is <NUM> to <NUM> wt-%, Mg <NUM> to <NUM> wt-% and donor <NUM> to <NUM> wt-% of the catalyst composition.

Detailed description of preparation of catalysts is disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

The Ziegler-Natta catalyst (ZN-C) is preferably used in association with an alkyl aluminum cocatalyst and optionally external donors.

The catalyst system which is used according to the present invention also comprises an aluminium alkyl compound, preferably of the general formula AlR<NUM>-nXn wherein R stands for straight chain or branched alkyl group having <NUM> to <NUM>, preferably <NUM> to <NUM> and more preferably <NUM> to <NUM> carbon atoms, X stands for halogen and n stands for <NUM>, <NUM>, <NUM> or <NUM>, which aluminium alkyl compound is added, and brought into contact with the droplets of the dispersed phase of the agitated emulsion before recovering the solidified particles of the catalyst.

It is further preferred that at least a part of the aluminium compound is added, in pure form or in the form of a solution, from shortly before the beginning of the emulsion formation until adding it to the washing liquid, e.g. toluene, in such an amount that the final Al content of the particles is from <NUM> to <NUM> wt. -%, preferably <NUM> to <NUM> wt. -% and most preferably <NUM> to <NUM> wt. by weight of the final catalyst particles. The most preferred Al content may vary depending upon the type of the Al compound and on the adding step. For example, in some cases the most preferred amount may be <NUM> to <NUM> wt.

Still further, preferably tri-(C<NUM>-C<NUM>)-alkyl aluminium compounds are used, triethylaluminium being most preferred.

In Ziegler-Natta catalysts alumimium alkyl compounds are used as cocatalysts, i.e. for activating the catalyst. During activation of polypropylene catalysts, alkyl aluminium does not only reduce and alkylate the active metal, but it has also influence on the donor composition. It is well-known that alkyl aluminium compounds can remove carboxylic acid esters, which are used as internal donors. Simultaneously, external donors can be fixed on the catalyst. Typically, tri-ethyl aluminium (TEAl) is used as cocatalyst and silanes as external donors as is disclosed e.g. in articles <NPL> and <NPL>.

In the catalysts used in the present invention, the internal donor, preferably substituted maleates and citraconates, can be significantly extracted from the catalyst with the use of the alkyl aluminium compound.

The extraction level is dependent on the concentration of the aluminium alkyl. The higher the concentration, the more of the internal donor can be extracted. Further, the addition of the external donor together with aluminium alkyl improves the donor exchange. The longer the reaction time is, the more external donor is bound on the catalyst.

As further component in the instant polymerization process an external donor (ED) is preferably present. Suitable external donors (ED) 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)<NUM>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, isopentyl, 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 cyclohexylmethyl dimethoxy silane donor (C-Donor) or the pentyl dimethoxy silane donor (D-donor), the latter especially preferred.

It is preferred that a solution containing alkyl aluminium and external donor in an organic solvent, e.g. pentane, are added to the catalyst after solidification of the catalyst particles.

The catalyst which is obtained by the above described process is a nonsupported Ziegler-Natta catalyst. Non-supported catalysts do not use any external carrier, contrary to conventional catalysts, e.g. conventional Ziegler-Natta catalysts, which are e.g. supported on silica or MgCl<NUM>.

Further preferred embodiments of the catalyst system production include all preferred embodiments as described in <CIT> and <CIT>.

The inventive polypropylene composition (C) further comprises a propylene homopolymer (H-PP).

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

Accordingly, it is preferred that the propylene homopolymer (H-PP) has a xylene soluble content (XCS) below <NUM> wt. -%, more preferably below <NUM> wt. -%, still more preferably below <NUM> wt.

It is preferred that the propylene homopolymer (H-PP) is featured by a high isotacticity. Accordingly, it is preferred that the propylene homopolymer (H-PP) has a mmmm pentad concentration of ≥ <NUM> %, preferably in the range of from <NUM> to <NUM> % determined by NMR-spectroscopy, and/or <NUM>,<NUM> erythro regio-defects of below <NUM> %, preferably below <NUM> %, more preferably below <NUM> % determined by <NUM>C-NMR spectroscopy.

It is especially preferred that the propylene homopolymer (H-PP) has a weight average molecular weight Mw in the range of <NUM> to <NUM>/mol, preferably in the range of <NUM> to <NUM>/mol, still more preferably in the range of <NUM> to <NUM>/mol.

Further it is preferred that the propylene homopolymer (H-PP) has a rather broad molecular weight distribution (Mw/Mn). Accordingly, it is preferred that the molecular weight distribution (Mw/Mn) of the propylene homopolymer (H-PP) is in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>, like in the range of <NUM> to <NUM>.

Additionally, it is preferred that the propylene homopolymer (H-PP) has a very low melt flow rate. Accordingly, the melt flow rate (<NUM>) measured according to ISO <NUM> of the propylene homopolymer (H-PP) is preferably 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>.

In a preferred embodiment, the propylene homopolymer (H-PP) is thermo mechanically stable. Accordingly, it is preferred that the propylene homopolymer (H-PP) has a melting temperature Tm of at least <NUM>, more preferably at least <NUM>, still more preferably at least <NUM>. A reasonable upper limit for Tm is <NUM>.

Preferably, the propylene homopolymer (H-PP) according to the present invention is a propylene homopolymer known in the art. In particular, it is preferred that the propylene homopolymer (H-PP) is the commercial propylene homopolymer HC101BF of Borealis AG.

The polypropylene composition (C) of the present invention may include additives (AD). Typical additives are acid scavengers, antioxidants, colorants, light stabilisers, plasticizers, slip agents, anti-scratch agents, dispersing agents, processing aids, lubricants, pigments, fillers, and the like.

Such additives are commercially available and for example described in "Plastic Additives Handbook", <NUM>th edition <NUM> of Hans Zweifel (pages <NUM> to <NUM>).

Furthermore, the term "additives (AD)" according to the present invention also includes carrier materials, in particular polymeric carrier materials.

Preferably the polypropylene composition (C) of the invention does not comprise (a) further polymer (s) different to the heterophasic propylene copolymer (RAHECO) and the plastomer (PL), in an amount exceeding <NUM> wt. -%, preferably in an amount exceeding <NUM> wt. -%, more preferably in an amount exceeding <NUM> wt. -%, based on the weight of the polpropylene composition (C). If an additional polymer is present, such a polymer is typically a polymeric carrier material for the additives (AD). Any carrier material for additives (AD) is not calcualted to the amount of polymeric compounds as indicated in the present invention, but to the amount of the respective additive.

The polymeric carrier material of the addtives (AD) is a carrier polymer to ensure a uniform distribution in the composition (C) of the invention. The polymeric carrier material is not limited to a particular polymer. The polymeric carrier material may be ethylene homopolymer, ethylene copolymer obtained from ethylene and α-olefin comonomer such as C<NUM> to C<NUM> α-olefin comonomer, propylene homopolymer and/or propylene copolymer obtained from propylene and α-olefin comonomer such as ethylene and/or C<NUM> to C<NUM> α-olefin comonomer.

The present invention is not only directed to the inventive polypropylene composition (C), but also to unoriented films made therefrom. Accordingly, in a further embodiment the present invention is directed to unoriented films, like cast films or blown films, e.g. air cooled blown films, comprising at least <NUM> wt. -%, preferably comprising at least <NUM> wt. -%, more preferably comprising at least <NUM> wt. -%, still more preferably comprising at least <NUM> wt. -%, yet more preferably comprising at least <NUM> wt. -%, of the inventive polypropylene composition (C). Preferably, the unoriented film consists of the inventive polypropylene composition (C).

One distinguishes between unoriented and oriented films (see for instance polypropylene handbook, Nello Pasquini, <NUM>nd edition, Hanser). Oriented films are typically monoaxially or biaxially oriented films, whereas unoriented films are cast or blown films. Accordingly, an unoriented film is not drawn intensively in machine and/or transverse direction as done by oriented films. Thus the unoriented film according to this invention is not a monoaxially or biaxially oriented film. Preferably the unoriented film according to the instant invention is a blown film or cast film.

In one specific embodiment the unoriented film is a cast film or an air-cooled blown film.

Preferably the unoriented film has a thickness of <NUM> to <NUM>, more preferably of <NUM> to <NUM>, like of <NUM> to <NUM>.

In the following the present invention is further illustrated by means of examples.

Calculation of comonomer content of the second propylene copolymer fraction (R-PP2): <MAT> wherein.

Calculation of the xylene cold soluble (XCS) content of the second propylene copolymer fraction (R-PP2): <MAT> wherein.

Calculation of melt flow rate MFR<NUM> (<NUM>) of the second propylene copolymer fraction (R-PP2): <MAT> wherein.

Calculation of comonomer content of the elastomeric propylene copolymer (E), respectively: <MAT> wherein.

MFR<NUM> (<NUM>) is measured according to ISO <NUM> (<NUM>, <NUM> load).

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was 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 (Singh, G. , Kothari, A. , Gupta, V. , Polymer Testing <NUM><NUM> (<NUM>), <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 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 WALTZ <NUM> 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>).

For polypropylene 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>.

For copolymers characteristic signals corresponding to the incorporation of ethylene were observed (<NPL>).

With regio defects also observed (<NPL>; <NPL>; <NPL>) correction for the influence of such defects on the comonomer content was required.

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.

Molecular weight averages (Mw, Mn), and the molecular weight distribution (MWD), i.e. the Mw/Mn (wherein Mn is the number average molecular weight and Mw is the weight average molecular weight), were determined by Gel Permeation Chromatography (GPC) according to ISO <NUM>-<NUM>:<NUM> and ASTM D <NUM>-<NUM>. A PolymerChar GPC instrument, equipped with infrared (IR) detector was used with <NUM> x Olexis and lx 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>µ<IMG>. 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>,<NUM>/mol to <NUM><NUM>/mol. Mark Houwink constants for PS, PE and PP used are as described per ASTM D <NUM>-<NUM>. All samples were prepared by dissolving <NUM> - <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 max. <NUM> under continuous gentle shaking in the autosampler of the GPC instrument. Intrinsic viscosity is measured according to DIN ISO <NUM>/<NUM>, October <NUM> (in Decalin at <NUM>).

The xylene solubles (XCS, wt. -%): Content of xylene cold solubles (XCS) is determined at <NUM> according ISO <NUM>; first edition; <NUM>-<NUM>-<NUM>. The part which remains insoluble is the xylene cold insoluble (XCI) fraction.

The hexane extractable fraction is determined according to the European Pharmacopeia <NUM> EP613. Test bar specimens of 80x10x4 mm<NUM> injection molded at <NUM> in line with EN ISO <NUM>-<NUM> were used in an amount of <NUM>, and the extraction was performed in <NUM> n-hexane by boiling under reflux for <NUM>, followed by cooling in ice water for <NUM>. The resulting solution is filtered under vacuum in less than <NUM>, followed by evaporation under nitrogen stream. After drying the evaporation residue it is weighed and the hexane extractable fraction calculated.

DSC analysis, melting temperature (Tm), crystallization temperature (Tc) and melt enthalpy (Hm): measured with a TA Instrument Q200 differential scanning calorimetry (DSC) on <NUM> to <NUM> samples. The crystallization temperature (Tc) is determined from the cooling step, while melting temperature (Tm) and melting enthalpy (Hm) are determined from the second heating step. Haze and clarity were determined according to ASTM D1003-<NUM> on cast films of <NUM> thickness produced on a monolayer cast film line with a melt temperature of <NUM> and a chill roll temperature of <NUM>.

Flexural Modulus: 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>. The Tensile Modulus and Elongation at Break in machine and transverse direction were determined according to ISO <NUM>-<NUM> at <NUM> on cast films of <NUM> thickness produced on a monolayer cast film line with a melt temperature of <NUM> and a chill roll temperature of <NUM>. Testing was performed at a cross head speed of <NUM>/min.

Steam sterilization was performed in a Systec D series machine (Systec Inc. The samples were heated up at a heating rate of <NUM>/min starting from <NUM>. After having been kept for <NUM> at <NUM>, they were removed immediately from the steam sterilizer and stored at room temperature till processed further.

The catalyst used in the polymerization processes for the heterophasic propylene copolymer (RAHECO) of the inventive examples (IE) was prepared as follows:.

Mg alkoxide solution was prepared by adding, with stirring (<NUM> rpm), into <NUM> of a <NUM> wt-% solution in toluene of butyl ethyl magnesium (Mg(Bu)(Et)), a mixture of <NUM> of <NUM>-ethylhexanol and <NUM> of butoxypropanol in a <NUM><NUM> stainless steel reactor. During the addition the reactor contents were maintained below <NUM>. After addition was completed, mixing (<NUM> rpm) of the reaction mixture was continued at <NUM> for <NUM> minutes. After cooling to room temperature <NUM> g of the donor bis(<NUM>-ethylhexyl)citraconate was added to the Mg-alkoxide solution keeping temperature below <NUM>. Mixing was continued for <NUM> minutes under stirring (<NUM> rpm).

<NUM> of TiCl<NUM> and <NUM> of toluene were added into a <NUM> stainless steel reactor. Under <NUM> rpm mixing and keeping the temperature at <NUM>, <NUM> of the Mg alkoxy compound prepared in example <NUM> was added during <NUM> hours. <NUM> of Viscoplex® <NUM>-<NUM> and <NUM> of heptane were added and after <NUM> hour mixing at <NUM> the temperature of the formed emulsion was raised to <NUM> within <NUM> hour. After <NUM> minutes mixing was stopped catalyst droplets were solidified and the formed catalyst particles were allowed to settle. After settling (<NUM> hour), the supernatant liquid was siphoned away. Then the catalyst particles were washed with <NUM> of toluene at <NUM> for <NUM> minutes followed by two heptane washes (<NUM>, <NUM>). During the first heptane wash the temperature was decreased to <NUM> and during the second wash to room temperature.

The thus obtained catalyst was used along with triethyl-aluminium (TEAL) as co-catalyst and dicyclopentyl dimethoxy silane (D-Donor) as donor.

The RAHECO was visbroken in a twin-screw extruder using an appropriate amount of (tert. -butylperoxy)-<NUM>,<NUM>-dimethylhexane (Trigonox <NUM>, distributed by Akzo Nobel, Netherlands) to achieve the target MFR<NUM> as mentioned in table <NUM>. The product was stabilized with <NUM> wt. -% of Irganox B225 (<NUM>:<NUM>-blend of Irganox <NUM> (Pentaerythrityl-tetrakis(<NUM>-(<NUM>',<NUM>'-di-tert. butyl-<NUM>-hydroxytoluyl)-propionate and tris (<NUM>,<NUM>-di-t-butylphenyl) phosphate) phosphite) of BASF AG, Germany) and <NUM> wt. -% calcium stearate.

The RAHECO (CE1) and the propylene homopolymer HC101BF by Borealis (H-PP, CE3) were melt blended on a co-rotating twin screw extruder at <NUM>. The polymer melt mixture was discharged and pelletized.

Claim 1:
Polypropylene composition (C), comprising
a) a matrix (M) comprising a random propylene copolymer (R-PP) and a propylene homopolymer (H-PP) with a melt flow rate MFR (<NUM>) measured according to ISO <NUM> in the range of <NUM> to <NUM>/<NUM>, and
b) an elastomeric propylene copolymer (E) dispersed in said matrix (M),
wherein said polypropylene composition (C) has
i) an intrinsic viscosity (IV) determined according to DIN ISO <NUM>/<NUM> (in Decalin at <NUM>) of the xylene soluble fraction (XCS) of at least <NUM> dl/g,
ii) a comonomer content of the xylene soluble fraction (XCS) of at least <NUM> mol-%, and
iii) a melt flow rate MFR<NUM> (<NUM>) measured according to ISO <NUM> of at least <NUM>/<NUM>.