Patent Description:
Heterophasic propylene copolymers are widely used in the packaging industry, due to their excellent combination of stiffness and impact behaviour. One can find the application of heterophasic propylene copolymers in many aspects of daily life. Still, there is the desire within the polymer and packaging industry to improve the available heterophasic polypropylene compositions in view of mechanical properties and especially the amount of extractable fractions. Having materials at hand, which have a low amount of polymer soluble in hexane is specifically required in the food packaging industry to fulfil the requirements of FDA and analogous national or supranational regulations. Hence, the hexane-soluble fraction according to the FDA method (C6FDA) is an important property for such applications.

The majority of heterophasic propylene copolymers are produced with Ziegler-Natta catalysts, which are known to produce polymers with a relative high amount of oligomers due to the "multi-active" nature of the catalyst itself. It is a known fact that the amount of oligomers and/or extractable fractions increase in polymer having higher melt flow rates. At the same time, polymers with good flowability are of special interest for injection moulding applications, as they enable production of thin-walled articles, especially when having extended flow lengths.

It is further known, that above mentioned oligomers are easily extractible, hence increasing the amounts of polymers extractable in xylene or hexane.

On the other hand, the amorphous rubbery phase, forming a dispersed phase within the heterophasic propylene copolymers, is essential for providing impact properties, but can - due to its extractability in solvents - negatively impact the amount of soluble fractions.

<CIT> claims propylene polymer compositions having a superior balance between hexane extractables and impact resistance. Claim <NUM> defines heterophasic polypropylene copolymers having an MFR<NUM> of <NUM> - <NUM>/<NUM>, comprising a propylene homo- or copolymer matrix (A) with an MFR<NUM> of <NUM> - <NUM>/<NUM>, and an ethylene or C4 -C10 -alpha-olefin propylene rubber phase (B) dispersed within the matrix, wherein the heterophasic polypropylene resin has an XCS fraction having an intrinsic viscosity of <NUM> to <NUM> dl/g, being composed of propylene monomer units in an amount of <NUM> - <NUM> wt%. The example is produced with a Ziegler Natta catalyst system and has <NUM> wt. -% of hexane extractables.

<CIT> covers soft heterophasic polyolefin compositions having relatively low hexane extractables in view of the targeted softness. The described polymers have around <NUM> wt. -% of hexane extractables (C6FDA).

<CIT> claims high-flow, high-impact SSC-based heterophasic PP with C2-rich EPR phase. No value for C6FDA is given. The amorphous phase is very ethylene-rich, the C2(XCS) of the sole example being <NUM> mol-% i.e. <NUM> wt.

<CIT>) is for SSC-based high-flow rTPO with enhanced mechanical properties. The materials have higher amounts of the amorphous fraction and higher comonomer content in the amorphous fraction. The amount of hexane solubles (C6FDA) is not disclosed, but can be expected to be rather high in view of the high XCS content.

<CIT> covers SSC-based impacted copolymers with excellent mechanical and optical properties. Claim <NUM> defines a heterophasic propylene polymer (HECO) comprising (a) <NUM> to <NUM> wt. % of a matrix component (M) selected from a propylene homo- or random copolymer (PP); and (b) <NUM> to <NUM> wt. % of an ethylene-propylene rubber (EPR), dispersed in the propylene homo- or random copolymer (PP), whereby the xylene cold soluble fraction (XCS) of the heterophasic propylene polymer (HECO) has an ethylene content of <NUM> to <NUM> wt. %; an intrinsic viscosity (IV), determined according to ISO <NUM>-<NUM>:<NUM>, of at least <NUM> dl/g; and the xylene cold insoluble fraction (XCI) of the heterophasic propylene polymer (HECO) has <NUM>,<NUM>-erythro regiodefects in an amount of at least <NUM> mol%.

The materials have lower flexural modulus and higher amounts of amorphous fraction.

<CIT> discloses a random heterophasic propylene copolymer with low MFR and rather low flexural modulus. The polymers disclosed have a higher amount of comonomer in the crystalline fraction as well as lower intrinsic viscosity of the soluble fraction. The polymers disclosed are not stiff enough to provide stable injection moulded articles.

Being faced with the drawbacks of the prior art and the requirements of the industry, it is the object of the invention to provide a heterophasic propylene copolymer with well balanced stiffness and impact strength, which shows both good processability in the sense of a high Melt Flow Rate (MFR<NUM>) as well as low amounts of the hexane extractible fraction, especially when tested according to FDA-requirements.

The above mentioned problem has been surprisingly solved by providing a heterophasic polypropylene composition comprising.

In a special embodiment, the present invention encompasses articles comprising said heterophasic polypropylene composition.

In a similar preferred embodiment, the present invention encompasses also the use of the heterophasic polypropylene composition for producing articles, especially injection moulded and/or thin walled articles as well as articles foreseen for packaging purposes. In a further embodiment, the invention covers a process for the production of the heterophasic polypropylene composition.

The heterophasic polypropylene composition of the present invention comprises <NUM> to <NUM> wt. -%, preferably <NUM> - <NUM> wt. -%, more preferably <NUM> to <NUM> wt. -% of a propylene homo- or copolymer, forming the crystalline matrix (a), which corresponds to the crystalline fraction CF determined by CRYSTEX QC method ISO6427-B.

Accordingly, the heterophasic polypropylene composition comprises an amorphous propylene ethylene elastomer dispersed in said crystalline matrix 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. Said amorphous elastomer corresponds to the soluble fraction (SF) determined by CRYSTEX QC method ISO6427-B.

The heterophasic polypropylene composition contains comonomers, preferably alpha-olefins selected from ethylene an C4 to C8 alpha olefins, preferably from ethylene, <NUM>-butene or <NUM>-hexene.

In a preferred embodiment, the heterophasic polypropylene composition comprises ethylene and <NUM>-butene as comonomer.

In an especially preferred embodiment, the heterophasic polypropylene composition comprises, only ethylene as the sole comonomer.

The comonomer content of the inventive polymer, C2 (total), may be 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.

The amount of the crystalline fraction (CF) of the heterophasic polypropylene composition is determined via determined by CRYSTEX QC method ISO6427-B and may be 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.

The crystalline fraction may comprise comonomer as lined out above. The comonomer content of the crystalline fraction, C2(CF), is 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.

The soluble fraction (SF) of the inventive polymer is also determined via CRYSTEX QC method ISO6427-B and may be 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.

The soluble fraction comprises comonomer as lined out above. The comonomer content of said soluble fraction (C2(SF)) is in the range of <NUM> to <NUM> wt. -%, preferably in the range of more than <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt.

The intrinsic viscosity if the soluble fraction, IV(SF), may be 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.

The heterophasic polypropylene composition of the present invention is characterised by a specific amount of polymer soluble in hexane, when determined according to FDA-method, (C6FDA; federal registration, title <NUM>, Chapter <NUM>, part <NUM>, section <NUM>, Annex B). C6FDA of the inventive polymer is 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.

The heterophasic polypropylene composition of the present invention has a specific ratio of the amount of soluble fraction (SF) to the amount of polymer soluble in hexane, when determined according to FDA-method.

A high(er) amount of the soluble fraction is beneficial for impact behaviour, as it reflects the amorphous propylene ethylene elastomer. Still at the same time, the amount of fractions soluble in hexane in view of FDA requirements should be as low as possible. The present invention hence provides a heterophasic polypropylene composition, which has an optimized ratio of said to aspects of soluble fractions, namely the ratio of SF/C6FDA.

The MFR230/<NUM> of the heterophasic polypropylene composition is 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>.

The heterophasic polypropylene composition may have a fraction soluble in cold xylene (XCS) 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.

The comonomer content of said fraction soluble in cold xylene (XCS) of the heterophasic polypropylene composition may be in the range of <NUM> to <NUM> wt. -%, preferably in the range of more than <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. The intrinsic viscosity IV(XCS) of said fraction soluble in cold xylene (XCS) of the heterophasic polypropylene composition may be 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.

The melting temperature, Tm(DSC), of the inventive polymer may be in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>.

The crystallisation temperature (DSC) of the inventive polymer may be in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>.

The crystalline matrix of the heterophasic polypropylene composition is a propylene homo- or copolymer, like a propylene random copolymer. It may contain alpha-olefins selected from ethylene an C4 to C8 alpha olefins, preferably from ethylene or <NUM>-butene.

In a preferred embodiment the crystalline matrix comprises ethylene as comonomer.

In an equally preferred embodiment, the crystalline matrix is a propylene homopolymer.

The crystalline matrix forms <NUM> to <NUM> wt. -%, preferably in the range of <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. -% of the heterophasic polypropylene composition.

The crystalline matrix may accordingly comprise comonomer, as out lined above, in an amount of <NUM> to <NUM> wt. -%, preferably in an amount of <NUM> to <NUM> wt. -%, more preferably in an amount of <NUM> to <NUM> wt.

The MFR230/<NUM> of the crystalline matrix (a) may be 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>.

The crystalline matrix may be multimodal, like bimodal. So, the crystalline matrix comprises at least two polypropylene fractions, namely a first and a second polypropylene fraction (a1 and a2), which may differ in view of their viscosity, their comonomer content, their comonomer type or more than one of these properties.

Preferably, the two polymer fractions comprised by the crystalline matrix differ in view of their comonomer content and/or their viscosities, especially in view of their viscosities. Accordingly it is preferred, that the first polypropylene fraction (a1) differs from the second polypropylene fraction (a2) in view of its comonomer content and its viscosity.

Preferably, the comonomer content and/or the viscosity of the second polypropylene fraction is lower than the comonomer content and/or the viscosity of the first polypropylene fraction.

It is especially preferred, that solely the viscosity of the second polypropylene fraction differs from the viscosity of the first polypropylene fraction, in particular that the viscosity of the second polypropylene fraction is lower than the viscosity of the first polypropylene fraction.

Preferably, the amount of the first polypropylene fraction in the crystalline matrix is equal to or higher than the amount of the second polypropylene fraction based on the total weight of the crystalline matrix.

The amount of the first polypropylene fraction in the crystalline fraction may be in the range of <NUM> - <NUM> wt. -%, preferably <NUM> - <NUM> wt. -%, more preferably in the range of <NUM> - <NUM> wt. -% based on the total weight of the crystalline matrix.

The amount of the second polypropylene fraction may be in the range of <NUM> - <NUM> wt. -%, preferably <NUM> - <NUM> wt. -%, more preferably in the range of <NUM> - <NUM> wt. -% based on the total weight of the crystalline matrix.

The ratio of the amount of the first and the second polypropylene fraction may be in the ranges of <NUM>:<NUM> to <NUM>:<NUM>, like <NUM>:<NUM> to <NUM>:<NUM>, preferably <NUM>:<NUM> to <NUM>:<NUM>.

As pointed out above, the crystalline matrix forms <NUM> to <NUM> wt. -%, preferably in the range of <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. -% of the heterophasic polypropylene composition.

The MFR230/<NUM> of first polypropylene fraction may be 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>.

The MFR230/<NUM> of second polypropylene fraction may be 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>.

Said first and second polypropylene fraction may independently from each other be a propylene homo- or copolymer as lined out above.

Each of the first and second polypropylene fraction may (independently from the other) comprise comonomer (as lined out above) in the range of <NUM> to <NUM> wt. -%, preferably 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.

Each of the first and second polypropylene fraction may (independently from the other) have an fraction soluble in cold xylene (XCS) 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.

The amorphous propylene ethylene elastomer provides <NUM> to <NUM> wt. -%, preferably in the range of <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt. -% of the heterophasic polypropylene composition.

The amorphous propylene ethylene elastomer is predominantly characterized via the soluble fraction of CRYSTEX QC method ISO6427-B.

Within the present application, the amorphous propylene ethylene elastomer of the heterophasic polypropylene composition corresponds to the soluble fraction of CRYSTEX QC method ISO6427-B and may be 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.

The soluble fraction comprises comonomer as lined out above.

The comonomer content of said soluble fraction (C2(SF)) is in the range of <NUM> to <NUM> wt. -%, preferably in the range of at least <NUM> to <NUM> wt. -%, more preferably in the range of <NUM> to <NUM> wt.

The intrinsic viscosity of the soluble fraction, IV(SF), may be 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.

The amorphous propylene ethylene elastomer (b) may also comprise alpha-olefins selected from C4 to C8 alpha olefins, preferably from <NUM>-butene or <NUM>-hexene. In a preferred embodiment the amorphous propylene ethylene elastomer (b) comprises ethylene and <NUM>-butene as comonomers.

In an especially preferred embodiment, the amorphous propylene ethylene elastomer (b) comprises, more preferably consists of propylene and ethylene as the sole comonomer.

The heterophasic polypropylene composition according to the invention may further comprise conventional additives in an amount of up to <NUM> wt. -%, preferably in an amount of <NUM> to <NUM> wt. -%, more preferably in an amount of <NUM> to <NUM> wt. Examples of additives include, but are not limited to, stabilizers such as antioxidants (for example sterically hindered phenols, phosphites/phosphonites, sulphur containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers, or blends thereof), metal deactivators (for example Irganox ® MD <NUM>), or UV stabilizers (for example hindered amine light stabilizers). Other typical additives are modifiers such as nucleating agents (for example sodium benzoate or sodium-<NUM>,<NUM>'-methylene-bis(<NUM>,<NUM>-di-t-butylphenyl)phosphate), antistatic or antifogging agents (for example ethoxylated amines and amides or glycerol esters), acid scavengers (for example Ca-stearate) and blowing agents for foaming. Further modifiers are lubricants and resins (for example ionomer waxes, polyethylene- and ethylene copolymer waxes, Fischer Tropsch waxes, montan-based waxes, fluoro-based compounds, or paraffin waxes), as well as slip and antiblocking agents (for example erucamide, oleamide, talc, natural silica and synthetic silica or zeolites) and mixtures thereof.

The heterophasic polypropylene composition of the present invention can be characterised by its improved, well balanced mechanical properties.

The Flexural Modulus according to ISO178 is in the range of <NUM> to <NUM> MPa, preferably in the range of <NUM> to <NUM> MPa, more preferably in the range of <NUM> to <NUM> MPa.

The Notched Impact Strength (NIS) as determined according to ISO179/1eA at +<NUM> may be in the range of <NUM> to <NUM>. 0kJ/m<NUM>, preferably in the range of <NUM> to <NUM> kJ/m<NUM>, more preferably in the range of <NUM> to <NUM> kJ/m<NUM>.

In a preferred embodiment, the heterophasic polypropylene composition is characterised by.

The heterophasic polypropylene composition of the present invention provides a high level of impact strength and a good flowability in the sense of a high MFR-value. This is reflected by a well-balanced ratio of the Notched Impact Strength (NIS) to the MFR:
Ratio NIS/MFR of the inventive polymer may be in the range <NUM> to <NUM>(J/m<NUM>)*(<NUM>/g), preferably in the range of <NUM> to <NUM> (kJ/m<NUM>)*(<NUM>/g), more preferably in the range of <NUM> to <NUM> (kJ/m<NUM>)*(<NUM>/g).

The present invention also discloses a process for polymerising the heterophasic polypropylene composition of the present invention.

It disclosed a process for preparing a heterophasic polypropylene composition claims by sequential polymerisation in the presence of a metallocene catalyst system, wherein.

Preferably, the intrinsic viscosity, namely the IV(SV) of the amorphous propylene ethylene elastomer IV(SF) is <NUM> to <NUM> dl/g.

The polymerisation process is done in the presence of a metallocene catalyst system as laid out herein.

The heterophasic polypropylene composition of the present invention is typically and preferably made in a multistep process well known in the art. A preferred multistage process is a loop-gas phase-process, such as developed by Borealis A/S, Denmark (known as BORSTAR(R) technology) described e.g. in patent literature, such as in <CIT> or in <CIT>.

The invention preferably relates to the copolymerisation of propylene, ethylene and optionally further comonomers as defined above and below, in an at least two, optionally three step process so as to form the heterophasic polypropylene composition. Preferably, propylene and ethylene are the only monomers used.

Ideally, the process of the invention employs two, preferably three main reactors, a first reactor operating in bulk, a first gas phase reactor and optionally a second gas phase reactor.

The process may also utilize a prepolymerisation step, taking place in a separate reactor before the three main reactors.

The crystalline matrix is present 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. -%, based on the total weight of the heterophasic polypropylene composition.

The elastomeric phase comprised in the heterophasic polypropylene composition and dispersed in above mentioned matrix, is present 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. -%, based on the total weight of the heterophasic polypropylene composition.

The comonomer content, C2 (total), of the inventive polymer may be 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.

The crystalline matrix being a propylene homo- or copolymer is being produced in a bulk step, then transferred to the second stage in which the amorphous propylene ethylene elastomer is produced in a first gas phase reactor (GPR1) in the presence of the first polypropylene fraction.

The comonomer content of the crystalline matrix may be 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.

In is particularly preferably, that the crystalline matrix (a) is a propylene homopolymer and comprises <NUM> wt. -% of comonomer.

The MFR of the crystalline matrix may be 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>. This applies regardless of the (bi)-modality of the crystalline matrix.

In case, the crystalline matrix is bimodal, then the first polypropylene fraction is being produced in a bulk step, then transferred to the second stage in which the second polypropylene fraction is prepared in a first gas phase reactor (GPR1) in the presence of the first polypropylene fraction.

This mixture, being the crystalline matrix and comprising said first and second polypropylene fractions together, is transferred to the third stage in which the amorphous propylene-ethylene elastomer is prepared in a gas phase reactor (GPR2) in the presence of the crystalline matrix.

The MFR230/<NUM> of the polymer produced in the first stage, being the first polypropylene fraction, may be 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>.

The MFR230/<NUM> of the polymer produced in the second stage, being the second polypropylene fraction, may be 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>.

Given the second polypropylene fraction is produced in the presence of the first polypropylene fraction, it is understood, that it's properties cannot be analysed as such, but have to be determined based on the properties of the first polypropylene fraction and the properties of the crystalline fraction.

In a preferred embodiment, the heterophasic polypropylene composition comprises.

Preferably, the amount of the first polypropylene fraction is equal or higher than the amount of the second polypropylene fraction based on the total weight of the crystalline matrix.

The amount of the first polypropylene fraction may be in the range of <NUM> - <NUM> wt. -%, preferably <NUM> - <NUM> wt. -%, more preferably in the range of <NUM> - <NUM> wt. -% based on the total weight of the crystalline matrix.

For bulk and gas phase copolymerisation reactions, the reaction temperature used will generally be in the range <NUM> to <NUM> (e.g. <NUM> to <NUM>), the reactor pressure will generally be in the range <NUM> to <NUM> bar for gas phase reactions with bulk polymerisation operating at slightly higher pressures. The residence time will generally be <NUM> to <NUM> hours (e.g. <NUM> to <NUM> hours).

The comonomer content of the first and second polypropylene fraction may be same or different and independently chosen from each other.

The comonomer content of the first polypropylene fraction is.

The comonomer content of the polymer produced in the first stage, namely the first polypropylene fraction, may be 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.

In is particularly preferably, that the first polypropylene fraction is a propylene homopolymer and comprises <NUM> wt. -% of comonomer.

The comonomer content of the polymer produced in the second stage, namely the second polypropylene fraction, may be 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.

In is particularly preferably, that the second polypropylene fraction is a propylene homopolymer and comprises <NUM> wt. -% of comonomer.

Within this application it is understood, that the comonomer content of the crystalline matrix, when available as distinct material sample, is determined via NMR analysis. When the comonomer content of the matrix and the dispersed fraction should be evaluated starting from the final polymer (comprising both the matrix and the dispersed fraction), then the matrix (and its properties) is reflected by the crystalline fraction (CF) determined according to CRYSTEX QC method, ISO <NUM>-B. Accordingly, the dispersed amorphous propylene ethylene elastomer is reflected by the soluble fraction (SF) determined according to CRYSTEX QC method, ISO <NUM>-B.

The heterophasic polypropylene composition according to the invention is preferably obtainable by a catalyst system comprising by a single-site catalyst, more preferably being obtainable by a metallocene catalyst complex and cocatalysts.

Preferred complexes of the metallocene catalyst include:.

Especially preferred is rac-anti-dimethylsilanediyl[<NUM>-methyl-<NUM>,<NUM>-bis-(<NUM>',<NUM>'-dimethylphenyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrahydro-s indacen-<NUM>-yl] [<NUM>-methyl-<NUM>-(<NUM>',<NUM>'-dimethylphenyl)-<NUM>-methoxy-<NUM>-tert-butylinden-<NUM>-yl] zirconium dichloride.

To form an active catalytic species it is normally necessary to employ a cocatalyst as is well known in the art.

According to the present invention a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst is used in combination with the above defined metallocene catalyst complex.

The aluminoxane cocatalyst can be one of formula (I):
<CHM>
where n is from <NUM> to <NUM> and R has the meaning below.

Aluminoxanes are formed on partial hydrolysis of organoaluminum compounds, for example those of the formula AlR<NUM>, AlR<NUM>Y and Al<NUM>R<NUM>Y<NUM> where R can be, for example, C<NUM>-C<NUM>-alkyl, preferably C<NUM>-C<NUM>-alkyl, or C<NUM>-C<NUM>-cycloalkyl, C<NUM>-C<NUM>-arylalkyl or -alkylaryl and/or phenyl or naphthyl, and where Y can be hydrogen, halogen, preferably chlorine or bromine, or C<NUM>-C<NUM>-alkoxy, preferably methoxy or ethoxy. The resulting oxygen-containing aluminoxanes are not in general pure compounds but mixtures of oligomers of the formula (II).

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

Also a boron containing cocatalyst is used in combination with the aluminoxane cocatalyst.

The catalyst complex ideally comprises a co-catalyst, certain boron containing cocatalysts are preferred. Especially preferred borates of use in the invention therefore comprise the trityl, i.e. triphenylcarbenium, ion. Thus the use of Ph<NUM>CB(PhF<NUM>)<NUM> and analogues therefore are especially favoured.

The catalyst system of the invention is used in supported form. The particulate support material used is silica or a mixed oxide such as silica-alumina, in particular silica.

The use of a silica support is preferred. The skilled man is aware of the procedures required to support a metallocene catalyst.

In a preferred embodiment, the catalyst system corresponds to the ICS3 of <CIT>.

The present invention also covers final articles, especially moulded articles comprising the heterophasic polypropylene composition of the present invention.

The articles may be injection moulded and may be used for packaging purposes or for application in the automotive industry.

Preferably said articles have a wall thickness of <NUM> to <NUM>, such as <NUM> to <NUM>, like <NUM> to <NUM>.

The present invention will now be described in further detail by the examples provided below:.

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

Xylene Cold Soluble fraction at room temperature (XCS, wt. -%) is determined at <NUM> according to ISO <NUM>; <NUM>th edition; <NUM>-<NUM>-<NUM>.

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

The Charpy notched impact strength (NIS) was measured according to ISO <NUM>1eA at +<NUM> or -<NUM>, using injection moulded bar test specimens of 80x10x4 mm<NUM> prepared in accordance with EN ISO <NUM>-<NUM>.

The amount of hexane extractable polymer according to FDA method (federal registration, title <NUM>, Chapter <NUM>, part <NUM>, section <NUM>, s. Annex B) was determined from films produced on a PM30 cast film extrusion line with about <NUM> melt temperature with L/D of <NUM> and a screw diameter of <NUM> (feed zone <NUM> D long, <NUM> deep, compression zone <NUM> D long, metering zone <NUM> D long, <NUM> deep utilising a screen pack <NUM> - <NUM> - <NUM> - <NUM> mesh/cm<NUM>). A <NUM> die with a <NUM> to <NUM> die gap, screw speed: <NUM> r/min, and chill roll temperature of water: both rolls <NUM> (heating-cooling unit), Air gap: <NUM>, Air knife blower air supply: <NUM> bar. The film thickness is <NUM>.

The amount of hexane soluble polymer is determined according to FDA method (federal registration, title <NUM>, Chapter <NUM>, part <NUM>, section <NUM>, s. Annex B) from the film samples prepared as described above. The extraction was performed at a temperature of <NUM> and an extraction time of <NUM> hours.

The crystalline (CF) and soluble fractions (SF) of the polypropylene (PP) compositions as well as the comonomer content and intrinsic viscosities of the respective fractions were analyzed by the CRYSTEX QC, Polymer Char (Valencia, Spain).

A schematic representation of the CRYSTEX QC instrument is shown in <FIG>. The crystalline and amorphous fractions are separated through temperature cycles of dissolution at <NUM>, crystallization at <NUM> and re-dissolution in a <NUM>,<NUM>,<NUM>-trichlorobenzene (<NUM>,<NUM>,<NUM>-TCB) at <NUM> as shown in <FIG>. Quantification of SF and CF and determination of ethylene content (C2) are achieved by means of an infrared detector (IR4) and an online <NUM>-capillary viscometer which is used for the determination of the intrinsic viscosity (IV).

The IR4 detector is a multiple wavelength detector detecting IR absorbance at two different bands (CH3 and CH2) for the determination of the concentration and the Ethylene content in Ethylene-Propylene copolymers. IR4 detector is calibrated with series of <NUM> EP copolymers with known Ethylene content in the range of <NUM> wt. -% to <NUM> wt. -% (determined by 13C-NMR) and various concentration between <NUM> and <NUM>/ml for each used EP copolymer used for calibration.

The amount of Soluble fraction (SF) and Crystalline Fraction (CF) are correlated through the XS calibration to the "Xylene Cold Soluble" (XCS) quantity and respectively Xylene Cold Insoluble (XCI) fractions, determined according to standard gravimetric method as per ISO16152. XS calibration is achieved by testing various EP copolymers with XS content in the range <NUM>-<NUM> Wt.

The intrinsic viscosity (IV) of the parent EP copolymer and its soluble and crystalline fractions are determined with a use of an online <NUM>-capillary viscometer and are correlated to corresponding IV's determined by standard method in decalin according to ISO <NUM>. Calibration is achieved with various EP PP copolymers with IV = <NUM>-<NUM> dL/g.

A sample of the PP composition to be analyzed is weighed out in concentrations of <NUM>/ml to <NUM>/ml. After automated filling of the vial with <NUM>,<NUM>,<NUM>-TCB containing <NUM>/l <NUM>,<NUM>-tert-butyl-<NUM>-methylphenol (BHT) as antioxidant, the sample is dissolved at <NUM> until complete dissolution is achieved, usually for <NUM>, with constant stirring of 800rpm.

As shown in a <FIG>, a defined volume of the sample solution is injected into the column filled with inert support where the crystallization of the sample and separation of the soluble fraction from the crystalline part is taking place. This process is repeated two times. During the first injection the whole sample is measured at high temperature, determining the IV[dl/g] and the C2[wt. -%] of the PP composition. During the second injection the soluble fraction (at low temperature) and the crystalline fraction (at high temperature) with the crystallization cycle are measured (wt. -% C2, IV).

Quantitative infrared (IR) spectroscopy was used to quantify the ethylene content of the poly(ethylene-co-propene) copolymers through calibration to a primary method. Calibration was facilitated through the use of a set of in-house non-commercial calibration standards of known ethylene contents determined by quantitative <NUM>C solution-state nuclear magnetic resonance (NMR) spectroscopy. The calibration procedure was undertaken in the conventional manner well documented in the literature. The calibration set consisted of <NUM> calibration standards with ethylene contents ranging <NUM>-<NUM> wt% produced at either pilot or full scale under a variety of conditions. The calibration set was selected to reflect the typical variety of copolymers encountered by the final quantitative IR spectroscopy method.

Quantitative IR spectra were recorded in the solid-state using a Bruker Vertex <NUM> FTIR spectrometer. Spectra were recorded on 25x25 mm square films of <NUM> thickness prepared by compression moulding at <NUM> - <NUM> and <NUM> - <NUM> mPa. For samples with very high ethylene contents (><NUM> mol%) <NUM> thick films were used. Standard transmission FTIR spectroscopy was employed using a spectral range of <NUM>-<NUM>-<NUM>, an aperture of <NUM>, a spectral resolution of <NUM>-<NUM>, <NUM> background scans, <NUM> spectrum scans, an interferogram zero filling factor of <NUM> and Blackmann-Harris <NUM>-term apodisation.

Quantitative analysis was undertaken using the total area of the CH<NUM> rocking deformations at <NUM> and <NUM>-<NUM> (AQ) corresponding to (CH<NUM>)><NUM> structural units (integration method G, limits <NUM> and <NUM>-<NUM>). The quantitative band was normalised to the area of the CH band at <NUM>-<NUM> (AR) corresponding to CH structural units (integration method G, limits <NUM>, <NUM>-<NUM>). The ethylene content in units of weight percent was then predicted from the normalised absorption (AQ / AR) using a quadratic calibration curve. The calibration curve having previously been constructed by ordinary least squares (OLS) regression of the normalised absorptions and primary comonomer contents measured on the calibration set.

Quantitative <NUM>C{<NUM>H} NMR spectra were recorded in the solution-state using a Bruker Avance 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 rotatory 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. 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>) and the comonomer fraction calculated as the fraction of ethylene in the polymer with respect to all monomer in the polymer: fE = ( E / ( P + E ) The comonomer fraction was quantified using the method of Wang et. The mole percent comonomer incorporation was calculated from the mole fraction: E [mol%] = <NUM> * fE. The weight percent comonomer incorporation was calculated from the mole fraction: E [wt%] = <NUM> * ( fE * <NUM> ) / ( (fE * <NUM>) + ((<NUM>-fE) * <NUM>) ).

The metallocene (MC) used was Anti-dimethylsilanediyl[<NUM>-methyl-<NUM>,<NUM>-di(<NUM>,<NUM>-dimethylphenyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrahydro-s-indacen-<NUM>-yl][<NUM>-methyl-<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-methoxy-<NUM>-tert-butylinden-<NUM>-yl] zirconium dichloride as disclosed in <CIT> as ICS3.

A steel reactor equipped with a mechanical stirrer and a filter net was flushed with nitrogen and the reactor temperature was set to <NUM>. Next silica grade DM-L-<NUM> from AGC Si-Tech Co, pre-calcined at <NUM> (<NUM>) was added from a feeding drum followed by careful pressuring and depressurising with nitrogen using manual valves. Then toluene (<NUM>) was added. The mixture was stirred for <NUM>. Next <NUM> wt% solution of MAO in toluene (<NUM>) from Lanxess was added via feed line on the top of the reactor within <NUM>. The reaction mixture was then heated up to <NUM> and stirred at <NUM> for additional two hours. The slurry was allowed to settle and the mother liquor was filtered off. The catalyst was washed twice with toluene (<NUM>) at <NUM>, following by settling and filtration. The reactor was cooled off to <NUM> and the solid was washed with heptane (<NUM>). Finally MAO treated SiO2 was dried at <NUM>° under nitrogen flow for <NUM> hours and then for <NUM> hours under vacuum (-<NUM> barg) with stirring. MAO treated support was collected as a free-flowing white powder found to contain <NUM>% Al by weight.

<NUM> wt% MAO in toluene (<NUM>) was added into a steel nitrogen blanked reactor via a burette at <NUM>. Toluene (<NUM>) was then added under stirring. The MC as cited above (<NUM>) was added from a metal cylinder followed by flushing with <NUM> toluene. The mixture was stirred for <NUM> minutes at <NUM>. Trityl tetrakis(pentafluorophenyl) borate (<NUM>) was then added from a metal cylinder followed by a flush with <NUM> of toluene. The mixture was stirred for <NUM> at room temperature. The resulting solution was added to a a stirred cake of MAO-silica support prepared as described above over <NUM> hour. The cake was allowed to stay for <NUM> hours, folled by drying under N2 flow at <NUM> for <NUM> and additionaly for <NUM> under vacuum (-<NUM> barg) under stirring. Dried catalyst was sampled in the form of pink free flowing powder containing <NUM>% Al and <NUM>% Zr.

CE1 is a heterophasic propylene ethylene copolymer, produced based on a Ziegler Natta catalyst. It has a starting MFR of <NUM>,<NUM>/<NUM> and is visbroken to MFR <NUM>/<NUM>.

CE2 is heterophasic propylene ethylene copolymer, produced based on a Ziegler Natta catalyst and a non-phthalate based internal donor.

Table <NUM> above indicates, that the heterophasic propylene copolymer has a well balanced stiffness and impact strength, combined with a good processability in the sense of a high Melt Flow Rate (MFR<NUM>),.

Claim 1:
Heterophasic polypropylene composition comprising
a) <NUM> to <NUM> wt.-% of a crystalline matrix being a propylene homo- or copolymer, said crystalline matrix corresponding to the crystalline fraction (CF) determined according to CRYSTEX QC method, ISO <NUM>-B and containing <NUM> to <NUM> wt.-% comonomer and
b) <NUM> to <NUM> wt.-% of an amorphous propylene-ethylene elastomer, optionally comprising of C4-C12 alpha -olefin(s) as further comonomers, dispersed in said crystalline matrix (a), wherein a) and b) add up to <NUM> wt.-%, and
wherein said amorphous propylene ethylene elastomer (b) corresponds to the soluble fraction (SF) determined according to CRYSTEX QC method, ISO <NUM>-B and contains <NUM> to <NUM> wt.-% of comonomer,
wherein the heterophasic polypropylene composition is characterised by
a Melt flow rate MFR230/<NUM> determined according to ISO1133 of <NUM> to <NUM>/<NUM>,
a hexane-soluble fraction according to FDA method, C6FDA federal registration, title <NUM>, Chapter <NUM>, part <NUM>, section <NUM>, Annex B, of <NUM> to <NUM> wt.-%,
a Flexural Modulus according to ISO178 of <NUM> to <NUM> MPa; and
wherein said heterophasic polypropylene composition is produced in the presence of a metallocene catalyst.