CN103827200A - Heterophasic propylene copolymer with excellent stiffness and impact balance - Google Patents

Abstract

Heterophasic propylene copolymer (HECO) comprising (a) a matrix (M) being a polypropylene (PP), said polypropylene (PP) comprises at least three polypropylene fractions (PP1), (PP2) and (PP3), the three polypropylene fractions (PP1), (PP2) and (PP3) differ from each other by the melt flow rate MFR2 (230 DEG C) measured according to ISO 1133, and (b) an elastomer (E) dispersed in said matrix (M), wherein the elastomer (E) is included in an amount of 20 wt.-% or more, based on the weight of the heterophasic propylene copolymer (HECO).

Description

Heterophasic propylene copolymer with excellent balance of stiffness and impact resistance

The present invention relates to a novel heterophasic propylene copolymer (HECO), its manufacture and use.

Heterophasic propylene copolymers are well known in the art. Such heterophasic propylene copolymers comprise a matrix, being a propylene homopolymer or a random propylene copolymer, in which is dispersed an elastomeric copolymer. Thus, the polypropylene matrix contains (finely) dispersed inclusions which are not part of the matrix and said inclusions contain the elastomer. The term inclusion means that the matrix and inclusions form distinct phases within the heterophasic propylene copolymer, said inclusions being visible eg by high resolution microscopy, such as electron microscopy or scanning force microscopy.

Thin thickness and light weight are recurring market demands as they allow energy and material savings. In order to provide materials with these characteristics, it is necessary to develop highly rigid materials with good impact resistance. High stiffness combined with high flow enables reduction of wall thickness without loss of stability, thus enabling the manufacture of large components. In addition, tool design can be kept simple for high flow materials because fewer gates are required. Furthermore, cycle time reductions are possible because the specific stiffness required for sample demolding is achieved in shorter cooling times. However, impact resistance needs to be kept at a high level. High flow materials generally exhibit high stiffness due to shorter polymer chains with fewer steric defects. However, impact performance is reduced due to the formation of shorter polymer chains with fewer entanglements. Therefore, it is a challenge to obtain materials with high flow and stiffness as well as good impact resistance.

Additionally, a distinction can be made between biaxial impact strength and triaxial impact strength. Although in heterophasic systems such as heterophasic propylene copolymers (HECO) both are extremely strongly dependent on morphology, increasing the impact strength of both types is quite challenging. This is due to the fact that they show optimum results at different particle sizes. Especially with small finely divided particles the impact strength (puncture energy) under biaxial stress is improved. This can be achieved with low molecular weight rubbers. However, this rubber is unfavorable for impact strength in a triaxial stress state (Charpy impact strength).

Employing the trimodal matrix concept leads to propylene with excellent stiffness and leads to heterophasic copolymers showing an excellent impact-stiffness balance. This good impact-stiffness balance is believed to be based on the fine dispersion of the rubber phase obtained by the high molecular weight fraction of the matrix. However, the application of this concept to heterophasic propylene copolymers (HECO) with high rubber content is not known, although they are necessary for automotive applications.

It is therefore an object of the present invention to obtain materials with high flow and stiffness and good impact resistance. In particular, it is an object of the present invention to obtain materials with high flowability, high stiffness, high puncture energy and high Charpy impact strength.

It was a finding of the present invention to provide a heterophasic propylene copolymer comprising a matrix with a broad molecular weight distribution and a rather high amount of elastomer, preferably with a rather low intrinsic viscosity.

Accordingly, the present application relates to a heterophasic propylene copolymer (HECO) comprising: (a) a matrix (M) which is polypropylene (PP), wherein said polypropylene (PP) comprises at least three polypropylene fractions ( PP1), (PP2) and (PP3), said three polypropylene fractions (PP1), (PP2) and (PP3) differing from each other in terms of melt flow rate _MFR2 (230°C) measured according to ISO1133; and (b) an elastomer (E) dispersed in said matrix (M), wherein said elastomer (E) is contained in an amount of 20% by weight or more based on the weight of said heterophasic propylene copolymer (HECO) ; optionally small amounts of polyethylene (PE) and optionally inorganic fillers (F).

The present invention also relates to a process for the preparation of the heterophasic propylene copolymer (HECO) as defined above, wherein said process comprises the step of blending the elastomer (E) with the matrix (M).

The present invention also relates to an article comprising the heterophasic propylene copolymer (HECO) as defined above, and the use of said heterophasic propylene copolymer (HECO), especially in automotive applications.

The present invention is described in more detail below.

Heterophasic Propylene Copolymer (HECO)

The heterophasic propylene copolymer (HECO) according to the present invention comprises polypropylene (PP) as matrix (M) and elastomer (E) dispersed therein. Thus, the polypropylene (PP) matrix contains (finely) dispersed inclusions which are not part of the matrix (M) and which contain the elastomer (E) and optionally also small amounts of crystalline polyethylene ( PE). The term inclusion means that the matrix (M) and inclusions form distinct phases within the heterophasic propylene copolymer (HECO), said inclusions being visible eg by high resolution microscopy, such as electron microscopy or scanning force microscopy.

Preferably the heterophasic propylene copolymer (HECO) according to the present invention comprises only polypropylene (PP) and elastomer (E) as polymer components. In other words, the heterophasic propylene copolymer (HECO) may also contain additives, but in a preferred embodiment does not contain more than 8.0% by weight based on the total weight of the heterophasic propylene copolymer (HECO), more preferably more than Other polymers in an amount of 6.0% by weight. One additional polymer that may be present in such low amounts is polyethylene (PE) mixed well with the elastomer (E), ie the elastomer (E) and optionally the polyethylene (PE) in the matrix (M) Inclusions are formed. Therefore, it is especially understood that the heterophasic propylene copolymer (HECO) of the present invention contains only polypropylene (PP), i.e. matrix (M), elastomer (E) and optionally small amounts of polyethylene (PE) as the only polymer components.

In a preferred aspect of the invention the heterophasic propylene copolymer (HECO) is characterized by a rather high melt flow rate. Melt flow rate depends primarily on average molecular weight. This is because long molecules give the material a lower flow tendency than short molecules. An increase in molecular weight means a decrease in MFR value. Melt flow rate (MFR) is measured in grams per 10 minutes of polymer discharged through a defined die under specified temperature and pressure conditions, and is a measure of polymer viscosity, and for each polymer Its viscosity is mainly affected by its molecular weight and branching degree. The melt flow rate measured at 230°C under a load of 2.16 kg (ISO 1133) is expressed as MFR ₂ (230°C). Therefore, it is preferred in the present invention that the heterophasic propylene copolymer (HECO) has an /10 minutes range, such as MFR ₂ (230° C.) in the range of 75.0 g/10 minutes to 180.0 g/10 minutes.

Preferably it is desired that the heterophasic propylene copolymer (HECO) is thermomechanically stable. Thus it is appreciated that the heterophasic propylene copolymer (HECO) has a melting temperature of at least 160°C, more preferably of at least 162°C, still more preferably in the range of 163°C to 170°C.

The elastomer (E) of the heterophasic propylene copolymer (HECO) constitutes the main part of the xylene cold soluble fraction of the heterophasic propylene copolymer (HECO). Thus, quite approximately, the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) can be equated to the elastomer (E) content of the heterophasic propylene copolymer (HECO). Therefore, the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) is preferably equal to or higher than 20% by weight, more preferably between 20% and 50% by weight, based on the heterophasic propylene copolymer (HECO) %, still more preferably in the range of 25% to 40% by weight, such as in the range of 25% to 35% by weight.

In yet another preferred embodiment the heterophasic propylene copolymer (HECO) of the present invention preferably has the following characteristics

(i) a tensile modulus measured according to ISO 527-2 of at least 1100 MPa, more preferably at least 1200 MPa, still more preferably in the range of 1100 MPa to 2500 MPa, such as in the range of 1200 MPa to 2200 MPa,

and / or

(ii) at least 3.5 kJ/m ² , more preferably at least 4.5 kJ/m ² , still more preferably in the range from 4.0 kJ/m ² to 10 kJ/m ² , such as at 4.0, measured according to ISO 179 (1eA; 23°C) Charpy notched impact strength in the range of kJ/ ^m2 to 8.0kJ/ ^m2 ,

and / or

(iii) Charpy measured according to ISO179 (1eA; -20°C) of at least 1.0 kJ/m ² , more preferably at least 1.2 kJ/m ² , still more preferably in the range of 1.5 kJ/m ² to 5.0 kJ/m ² notched impact strength,

and / or

(iv) at least 6J, more preferably at least 12J, still more preferably in the range of 8J to 28J, such as in the range of 12J to 25J, determined according to ISO6603-2 using the Instrumented Falling Weight (IFW) test on a 60 x 60 x 2mm injection molded part The piercing energy within (+23°C),

and / or

(iv) at least 3J, more preferably at least 7J, still more preferably in the range of 5J to 18J, such as in the range of 7J to 15J, determined according to ISO6603-2 using the Instrumented Falling Weight (IFW) test on a 60 x 60 x 2mm injection molded part The piercing energy within (-20°C).

The values for piercing energy preferably apply to the heterophasic propylene copolymer (HECO) without filler (F).

The individual components of the heterophasic propylene copolymer (HECO), namely matrix (M) and elastomer (E) are defined in more detail below.

As mentioned above, the matrix (M) is polypropylene (PP), more preferably random propylene copolymer (R-PP) or propylene homopolymer (H-PP), especially preferably propylene homopolymer (H-PP) PP).

Accordingly, the comonomer content of the polypropylene (PP) is equal to or less than 1.0% by weight, still more preferably not more than 0.8% by weight, still more preferably not more than 0.5% by weight. The above weight percentages are based on the total weight of polypropylene (PP).

As mentioned above the polypropylene (PP) is preferably a propylene homopolymer (H-PP).

The expression propylene homopolymer as used throughout the present invention relates to a polypropylene consisting essentially of propylene units, ie consisting of equal to or less than 99.5% by weight of propylene units. In a preferred embodiment only propylene units are detectable in the propylene homopolymer. Comonomer content was determined by FT infrared spectroscopy as described in the Examples section below.

If the polypropylene (PP) is a random propylene copolymer (R-PP), it is understood that said random propylene copolymer (R-PP) comprises monomers copolymerizable with propylene, such as comonomers such as ethylene and/or C ₄ to C ₁₂ alpha-olefins, especially ethylene and/or C ₄ to C ₈ alpha-olefins such as 1-butene and/or 1-hexene. Preferably, the random propylene copolymer (R-PP) according to the present invention comprises monomers copolymerizable with propylene selected from ethylene, 1-butene and 1-hexene, in particular from ethylene, 1-butene 1-hexene and 1-hexene are copolymerizable monomers with propylene. More specifically, the random propylene copolymer (R-PP) of the present invention comprises, in addition to propylene, units derived from ethylene and/or 1-butene. In a preferred embodiment the random propylene copolymer (R-PP) comprises units derivable from ethylene and propylene only.

In addition, it will be appreciated that the random propylene copolymer (R-PP) preferably has a % to a comonomer content in the range of 1.0% by weight. The above weight percentages are based on the total weight of the random propylene copolymer (R-PP).

The term "random" denotes the propylene copolymer (R-PP) as well as the first random propylene copolymer (R-PP1), the second random propylene copolymer (R-PP2) and the third random propylene copolymer (R-PP - The comonomers of PP3) are distributed randomly within the propylene copolymer. The term "random" is understood according to IUPAC (Glossary of Fundamental Terms in Polymer Science; IUPAC Recommendation, 1996).

As mentioned above the heterophasic propylene copolymer (HECO) has a rather high melt flow rate. The same is therefore true for its matrix (M), ie polypropylene (PP). It is therefore preferred that the polypropylene (PP) has a weight measured according to ISO 1133 in the range of 30.0 g/10 min to 500.0 g/10 min, more preferably in the range of 40.0 g/10 min to 400.0 g/10 min, still more preferably Melt flow rate MFR ₂ (230° C.) in the range of 50.0 g/10 min to 300.0 g/10 min.

It will also be appreciated that the matrix (M) of the heterophasic propylene copolymer (HECO) is characterized by a suitably broad molecular weight distribution. It will therefore be appreciated that the matrix of the heterophasic propylene copolymer (HECO), i.e. polypropylene (PP), has an Within, such as a molecular weight distribution (MWD) of 4.0 to 7.0.

Furthermore, polypropylene (PP) can be defined by its molecular weight. It will therefore be appreciated that polypropylene (PP) has a mass measured by gel permeation chromatography (GPC; ISO 16014-4:2003) equal to or less than 175 kg/mole, more preferably equal to or less than 165 kg/mole, still more preferably at 75 A weight average molecular weight (Mw) in the range of kg/mole to 160 kg/mole, still more preferably in the range of 80 kg/mole to 150 kg/mole.

The xylene cold soluble (XCS) content of polypropylene (PP) is quite moderate. Therefore, the xylene cold soluble (XCS) content is preferably equal to or less than 4.0 wt%, more preferably equal to or less than 3.5 wt%, still more preferably in the range of 0.5 wt% to 3.0 wt%, such as 0.5 wt% to 2.8% by weight. The above weight percentages are based on the total weight of polypropylene (PP).

As mentioned above, the polypropylene (PP) comprises at least three, more preferably three polypropylene fractions (PP1), (PP2) and (PP3), still more preferably composed of three polypropylene fractions (PP1), (PP2 ) and (PP3), the three polypropylene fractions (PP1), (PP2) and (PP3) differing from each other in terms of melt flow rate MFR ₂ (230°C) measured according to ISO1133.

In a preferred embodiment the first polypropylene fraction (PP1) has a measured according to ISO 1133 of 80 g/10 min to 500 g/10 min, more preferably 150 g/10 min to 480 g/10 min, still more A melt flow rate MFR ₂ (230° C.) of 200 g/10 min to 450 g/10 min, still more preferably 250 g/10 min to 450 g/10 min is preferred.

Additionally, the second polypropylene fraction (PP2) preferably has a 20 g/10 min to 300 g/10 min, more preferably 50 g/10 min to 250 g/10 min, still more preferably 70 g/10 min measured according to ISO 1133 A melt flow rate MFR ₂ (230° C.) of 10 min to 220 g/10 min, still more preferably 100 g/10 min to 200 g/10 min.

Furthermore, the polypropylene fraction (PP3) preferably has a 1 g/10 min to 15 g/10 min measured according to ISO 1133, more preferably 2 g/10 min to 15 g/10 min, still more preferably 2 g/10 min A melt flow rate MFR ₂ (230° C.) of up to 12 g/10 min, still more preferably between 3 g/10 min and 10 g/10 min.

Preferably the melt flow rate _MFR2 (230°C) decreases from the first polypropylene fraction (PP1) to the third polypropylene fraction (PP3). Accordingly, the ratio [MFR(PP1)/MFR(PP3)] of the melt flow rates _MFR2 (230°C) of the first polypropylene fraction (PP1) and the third polypropylene fraction (PP3) is preferably at least 10, more preferably at least 20, still more preferably at least 30, such as in the range of 30 to 60, and/or between the melt flow rates _MFR2 (230°C) of the second polypropylene fraction (PP2) and the third polypropylene fraction (PP3) The ratio [MFR(PP2)/MFR(PP3)] is preferably at least 5, more preferably at least 7, still more preferably at least 10.

In another preferred embodiment the melt flow rate MFR ₂ (230°C) decreases from the first polypropylene fraction (PP1) to the second polypropylene fraction (PP2) and from the second polypropylene fraction (PP2) Decreases to the third polypropylene fraction (PP3). Therefore, the second polypropylene fraction (PP2) preferably has a lower melt flow rate _MFR2 (230°C) than the first polypropylene fraction (PP1), but a higher melt flow rate than the third polypropylene fraction (PP3) Flow rate MFR ₂ (230°C).

Therefore, the third polypropylene fraction (PP3) preferably has the lowest melt flow of all polymers present in the three polypropylene fractions (PP1), (PP2) and (PP3), more preferably polypropylene (PP) Rate MFR ₂ (230°C).

Preferably at least one of the polypropylene fractions (PP1), (PP2) and (PP3) is a propylene homopolymer, even more preferably all the polypropylene fractions (PP1), (PP2) and (PP3) are Propylene homopolymer.

Therefore in a preferred embodiment the matrix (M) of the heterophasic propylene copolymer (HECO), i.e. the polypropylene (PP) comprises

(a) being a first polypropylene fraction (PP1) of a first propylene homopolymer (H-PP1) or a first random propylene copolymer (R-PP1),

(b) a second polypropylene fraction (PP2) being a second propylene homopolymer (H-PP2) or a second random propylene copolymer (R-PP2),

(c) a third polypropylene fraction (PP3) being a third propylene homopolymer (H-PP3) or a third random propylene copolymer (R-PP3),

Provided that at least one of the three fractions PP1, PP2 and PP3 is a propylene homopolymer, preferably at least the first polypropylene fraction (PP1) is a propylene homopolymer, more preferably all three fractions (PP1), ( Both PP2) and (PP3) are propylene homopolymers.

As mentioned above, it is particularly preferred that at least the first polypropylene fraction (PP1) is a propylene homopolymer, the so called first propylene homopolymer (H-PP1). Even more preferably, the first polypropylene fraction (PP1) has the highest melt flow rate _MFR2 (230°C) of the three polypropylenes (PP1), (PP2) and (PP3).

Still more preferably, in addition to the first polypropylene fraction (PP1 ), the second polypropylene fraction (PP2) or the third polypropylene fraction (PP3) is also a propylene homopolymer. In other words, preferably the polypropylene (PP) comprises only one polypropylene fraction which is a random propylene copolymer, preferably consists of only one polypropylene fraction which is a random propylene copolymer. Thus, the second polypropylene fraction (PP2) is a propylene homopolymer, the so-called second propylene homopolymer (H-PP2), or the third polypropylene fraction (PP3) is a propylene homopolymer, the so-called second Tripropylene homopolymer (H-PP3).

Especially preferably all three polypropylene fractions (PP1), (PP2) and (PP3) are propylene homopolymers.

The three polypropylene fractions (PP1), (PP2) and (PP3) are described in more detail below.

As mentioned above, the polypropylene fractions (PP1), (PP2) and (PP3) may be random propylene copolymers or propylene homopolymers. In any case the comonomer content should be rather low for each of the polypropylene fractions (PP1), (PP2) and (PP3). Accordingly, the comonomer content of each of the three polypropylene fractions (PP1), (PP2) and (PP3) is not greater than 1.0 wt%, still more preferably not greater than 0.8 wt%, still more preferably not greater than 0.5 weight%. In the case of random propylene copolymer fractions (R-PP1), (R-PP2) and (R-PP3), it is understood that for random propylene copolymer fractions (R-PP1), (R-PP2) and Each of (R-PP3) has a comonomer content in the range of greater than 0.2 wt% to 3.0 wt%, more preferably in the range of greater than 0.2 wt% to 2.5 wt%, still more preferably in the range of 0.2 wt% to the range of 2.0% by weight. The above weight percentages are based on the weight of the individual random propylene copolymer fractions.

(R-PP1), (R-PP2) and (R-PP3) independently of each other comprise monomers copolymerizable with propylene, for example comonomers such as ethylene and/or _C4 to _C12 alpha-olefins, In particular ethylene and/or _C4 to _C8 alpha-olefins such as 1-butene and/or 1-hexene. Preferably, (R-PP1), (R-PP2) and (R-PP3) independently of each other comprise monomers copolymerizable with propylene selected from the group consisting of ethylene, 1-butene and 1-hexene, especially each other Consisting independently of monomers copolymerizable with propylene selected from the group consisting of ethylene, 1-butene and 1-hexene. More specifically, (R-PP1), (R-PP2) and (R-PP3) independently of one another comprise, in addition to propylene, units derived from ethylene and/or 1-butene. In a preferred embodiment, (R-PP1), (R-PP2) and (R-PP3) have the same comonomer except propylene. Thus, in an especially preferred embodiment, (R-PP1), (R-PP2) and (R-PP3) comprise units derived from ethylene and propylene only.

As mentioned above the first polypropylene fraction (PP1) is a random propylene copolymer fraction (R-PP1) or a propylene homopolymer fraction (H-PP1), preferably a propylene homopolymer fraction (H-PP1).

The xylene cold soluble (XCS) content of the first polypropylene fraction (PP1) is preferably equal to or less than 4.0 wt%, more preferably equal to or less than 3.5 wt%, still more preferably in the range of 0.8 wt% to 4.0 wt% , such as in the range of 0.8% by weight to 3.0% by weight. The above weight percentages are based on the weight of the first polypropylene fraction (PP1).

As mentioned above, the first polypropylene fraction (PP1) is characterized by a rather high melt flow rate _MFR2 (230°C). It is therefore understood that the melt flow rate MFR ₂ (230° C.) measured according to ISO1133 is equal to or greater than 80 g/10 min, preferably equal to or greater than 150 g/10 min, more preferably between 80 g/10 min and 500 g/10 min. In the range of 10 minutes, still more preferably in the range of 150 g/10 min to 480 g/10 min, still more preferably in the range of 200 g/10 min to 450 g/10 min, still more preferably in the range of 250 g /10 minutes to 450 g/10 minutes.

Alternatively or additionally, the first polypropylene fraction (PP1) is limited to low molecular weight. It will therefore be appreciated that the first polypropylene fraction (PP1) has a measured by gel permeation chromatography (GPC; ISO 16014-4:2003) equal to or less than 130 kg/mol, more preferably equal to or less than 110 kg/mol, still more Weight average molecular weights (Mw) in the range of 72 kg/mol to 110 kg/mol, still more preferably in the range of 75 kg/mol to 100 kg/mol are preferred.

The second polypropylene fraction (PP2) can be a random propylene copolymer fraction (second random propylene copolymer fraction (R-PP2)) or a propylene homopolymer fraction (second propylene homopolymer fraction (H-PP2) ), preferably the propylene homopolymer fraction (the second propylene homopolymer fraction (H-PP2)).

The xylene cold soluble (XCS) content of the second polypropylene fraction (PP2) is preferably equal to or less than 4.0 wt%, more preferably equal to or less than 3.5 wt%, still more preferably in the range of 0.8 wt% to 4.0 wt% , such as in the range of 0.8% by weight to 3.0% by weight. The above weight percentages are based on the weight of the second polypropylene fraction (PP2).

As mentioned above, the second polypropylene fraction (PP2) has a higher melt flow rate _MFR2 (230°C) than the third polypropylene fraction (PP3). On the other hand, the melt flow rate MFR ₂ (230°C) of the first polypropylene fraction (PP1) may be higher than or equal to, preferably higher than, the melt flow rate MFR ₂ (230°C) of the second polypropylene fraction (PP2). ). It will therefore be appreciated that the second polypropylene fraction (PP2) has a weight measured according to ISO 1133 in the range of 20 g/10 min to 300 g/10 min, preferably in the range of 50 g/10 min to 250 g/10 min, more preferably A melt flow rate MFR ₂ (230° C.) in the range of 70 g/10 min to less than 220 g/10 min, still more preferably in the range of 100 g/10 min to 200 g/10 min is preferred.

The third polypropylene fraction (PP3) may be a random propylene copolymer fraction (third random propylene copolymer fraction (R-PP3)) or a propylene homopolymer fraction (third propylene homopolymer fraction (H-PP3) ), preferably the propylene homopolymer fraction (the third propylene homopolymer fraction (H-PP3)).

The xylene cold soluble (XCS) content of the third polypropylene fraction (PP3) is preferably equal to or less than 4.0 wt%, more preferably equal to or less than 3.5 wt%, still more preferably in the range of 0.8 wt% to 4.0 wt% , such as in the range of 0.8% by weight to 3.0% by weight. The above weight percentages are based on the weight of the third polypropylene fraction (PP3).

As mentioned above, the third polypropylene (PP3) preferably has the lowest melt flow rate MFR ₂ (230°C) of the three polypropylene fractions (PP1), (PP2) and (PP3), more preferably polypropylene The lowest melt flow rate MFR ₂ (230° C.) among the polymer fractions present in (PP). It will therefore be appreciated that the third polypropylene (PP3) has a mass in the range of 1.0 g/10 min to 15.0 g/10 min, preferably in the range of 2.0 g/10 min to 15.0 g/10 min, still more A melt flow rate MFR ₂ (230° C.) in the range of 2.0 g/10 min to 12.0 g/10 min, such as 3 g/10 min to 10 g/10 min is preferred.

Excellent results are obtained if the individual fractions are present in specific amounts. Thus preferably, the melt flow rate MFR ₂ (230° C.) measured according to ISO 1133 is in the range of 1.0 g/10 min to 15.0 g/10 min (preferably in the range of 2.0 g/10 min to 15.0 g/10 min, Still more preferably in the range of 2.0 g/10 min to 12.0 g/10 min) the amount of the polypropylene fraction with a melt flow rate MFR ₂ (230°C), preferably the amount of the third polypropylene fraction (PP3) is at 10% by weight to 30% by weight, more preferably in the range of 10% to 25% by weight, still more preferably in the range of 15% to 25% by weight. The above values are based on the total weight of the matrix (M), preferably on the amount of the polypropylene fractions (PP1), (PP2) and (PP3) together.

It should also be understood that the amount of the polypropylene fraction, preferably the first polypropylene fraction (PP1), has a melt flow rate MFR ₂ (230°C) measured according to ISO 1133 in the range of 80.0 g/10 min to 500.0 g/10 min The amount is in the range of 20% by weight to 55% by weight, preferably in the range of 25% by weight to 45% by weight, more preferably in the range of 30% by weight to 45% by weight, still more preferably 35% by weight to 45% by weight . The above values are based on the total weight of the matrix (M), preferably on the amount of the polypropylene fractions (PP1), (PP2) and (PP3) together.

Finally, the remainder of the three polypropylene fractions (PP1), (PP2) and (PP3), preferably the second polypropylene fraction (PP2) is in the range of 20% to 55% by weight, preferably 25% by weight % to 55% by weight, more preferably in the range of 30% to 45% by weight, still more preferably 35% to 45% by weight. The above values are based on the total amount of matrix (M), ie polypropylene (PP), preferably on the amount of polypropylene fractions (PP1), (PP2) and (PP3) together.

Thus in a preferred embodiment the fraction of the polypropylene, preferably the third polypropylene, has a melt flow rate MFR ₂ (230°C) measured according to ISO 1133 in the range of 1.0 g/10 min to 15.0 g/10 min A fraction (PP3) of a polypropylene fraction, preferably a first polypropylene fraction (PP1), with a melt flow rate MFR ₂ (230°C) measured according to ISO 1133 in the range of 80.0 g/10 min to 500.0 g/10 min The weight ratio [PP3/PP1] is in the range of 10/45 to 25/30, more preferably in the range of 1/3 to 5/7.

Very good results can be obtained provided that the polypropylene (PP) contains

(a) 20.0% to 55.0% by weight, preferably 25.0% to 45.0% by weight of the first polypropylene (PP1),

(b) 20.0% to 55.0% by weight, preferably 25.0% to 55.0% by weight of the second polypropylene (PP2), and

(c) 10.0% to 30.0% by weight, preferably 15.0% to 25.0% by weight of a third polypropylene (PP3).

In one embodiment the polypropylene (PP) is produced in a sequential polymerisation process, preferably as described in detail below. Thus, the three polypropylene fractions (PP1), (PP2) and (PP3) are homogeneous mixtures, which cannot be obtained by mechanical blending. In another embodiment the polypropylene (PP) is obtained by blending polypropylene fractions (PP1), (PP2) and (PP3).

Another essential component of the present invention is the elastomer (E).

As mentioned above, the properties of the elastomer (E) mainly affect the xylene cold solubles (XCS) of the final heterophasic propylene copolymer (HECO). In other words, the properties defined below for the elastomer (E) apply equally to the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO).

The elastomer may be any elastomer. However, in a preferred embodiment of the present invention, the elastomer (E) is an ethylene copolymer elastomer comprising ethylene monomer _units and comonomer units, wherein the comonomer is selected from _alpha - Olefins, preferably propylene, 1-butene, 1-hexene and 1-octene; or C ₅ to C ₂₀ α,ω-dienes, preferably 1,7-octadiene. In a more preferred embodiment, the comonomer is selected from propylene, 1-butene, 1-hexene and 1-octene, with 1-octene being especially preferred.

In one embodiment, the elastomer (E) has a melt flow rate MFR ₂ (190° C.) measured according to ISO 1133 of 10 g/10 min to 80 g/10 min. More preferably, elastomer (E) has a Minute melt flow rate MFR ₂ (190° C.).

In another preferred embodiment, the elastomer (E) has an intrinsic viscosity of 0.7 dl/g to 2.5 dl/g, preferably 0.8 dl/g to 2.0 dl/g, more preferably 0.8 dl/g to 1.5 dl/g number. Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in decalin at 135°C).

Furthermore, the elastomer (E) preferably has a weight of less than 940 kg/m ³ , more preferably 920 kg/m ³ or lower, still more preferably in the range of 850 kg/m ³ to 920 kg/m ³ , still more preferably in the range of 860 kg/m 3 Density in the range of ³ to 910kg/m ³ . As mentioned above, the heterophasic propylene copolymer (HECO) may also comprise polyethylene (PE), in particular polyethylene (PE) as defined below. In this case, preferably, the mixture of elastomer and polyethylene (PE) exhibits a density as given in this paragraph.

An important aspect of the present invention is that the amount of elastomer (E) in the heterophasic propylene copolymer (HECO) is rather high. Therefore, preferably, the elastomer (E) is equal to or greater than The heterophasic propylene copolymer (HECO) is present in an amount of 20.0 wt%, more preferably in an amount equal to or greater than 20.0 wt% to 50.0 wt%, still more preferably in an amount of 25.0 wt% to 40.0 wt%.

Therefore, preferably, the weight ratio ([M]/[E]) between the matrix (M) and the elastomer (E) is less than 4.0, more preferably 1.0 to less than 4.0, still more preferably 1.5 to 3.0.

Therefore, preferably the heterophasic propylene copolymer (HECO) comprises, based on the total amount of polypropylene (PP) and elastomer (E), based on the heterophasic propylene copolymer (HECO)

(a) less than 80% by weight, more preferably 50.0% to 80.0% by weight, still more preferably 60.0% to 75.0% by weight of matrix (M), i.e. polypropylene (PP), and

(b) Equal to or greater than 20% by weight, more preferably 20.0% to 50.0% by weight, still more preferably 25.0% to 40.0% by weight of elastomer (E).

Polyethylene (PE)

The heterophasic propylene copolymer (HECO) according to the invention optionally also comprises crystalline polyethylene (PE). The expression "crystalline" means that polyethylene (PE) is distinguished from elastomer (E). Polyethylene (PE) is crystalline and insoluble in cold xylene, whereas elastomer (E) is mainly amorphous and thus soluble in cold xylene. In a preferred embodiment the polyethylene (PE) is high density polyethylene (HDPE). The high density polyethylene (HDPE) used according to the invention is well known in the art and commercially available.

High density polyethylene (HDPE) preferably has a melting point of 15 g/10 min to 45 g/10 min, preferably 20 g/10 min to 40 g/10 min, more preferably 25 g/10 min to 35 g/10 min. Bulk flow rate MFR ₂ (190°C).

High density polyethylene (HDPE) generally has a mass of at least 940 kg/m ³ , preferably at least 945 kg/m ³ , more preferably at least 955 kg/m ³ , still more preferably in the range of 945 kg/m ³ to 970 kg/m ³ , still more preferably in the Density in the range of 950kg/m ³ to 965kg/m ³ .

Based on the total weight of the heterophasic propylene copolymer (HECO), the high density polyethylene (HDPE) may be present in an amount of up to 8 wt%, preferably up to 5 wt%, more preferably in the range of 0 to 8 wt%, such as in the range of 1 wt% to 8% by weight, still more preferably in an amount in the range of 0 to 6% by weight, such as in the range of 1% to 6% by weight.

When present, polyethylene (PE), ie high density polyethylene (HDPE), is also dispersed in the matrix (M) of the heterophasic propylene copolymer (HECO), ie polypropylene (PP). More precisely polyethylene (PE), ie high density polyethylene (HDPE), is thoroughly mixed with the elastomer so as to form inclusions of the heterophasic propylene copolymer (HECO) together with the elastomer (E).

Inorganic filler

In addition to the polymer components discussed above, the heterophasic propylene copolymer (HECO) may optionally comprise up to 25% by weight, preferably up to 22% by weight, based on the total weight of the heterophasic propylene copolymer (HECO), More preferred are inorganic fillers (F) in amounts ranging from 4% to 25% by weight, still more preferably from 5% to 20% by weight. Preferably, the inorganic filler (F) is phyllosilicate, mica or wollastonite. Even more preferably, the inorganic filler (F) is selected from mica, wollastonite, kaolinite, smectite, montmorillonite and talc. Most preferably, the inorganic filler (F) is talc.

The mineral filler (F) preferably has a cut-off particle size d95 [mass percent] equal to or less than 20 μm, more preferably in the range of 2.5 μm to 10 μm, such as in the range of 2.5 μm to 8.0 μm.

Generally, the inorganic filler (F) has a value of less than 22 m ² /g, more preferably less than 20 m ² /g, still more preferably less than 18 m ² /g measured according to the known BET method using N ₂ gas as analytical adsorbate surface area. Inorganic fillers (F) satisfying these requirements are preferably anisotropic mineral fillers (F), such as talc, mica and wollastonite.

other components

The inventive heterophasic propylene copolymer (HECO) may contain typical additives such as acid scavengers (AS), antioxidants (AO), nucleating agents (NA), hindered amine light stabilizers (HALS), slip agents (SA) and pigments. Preferably, in the heterophasic propylene copolymer (HECO) of the present invention the amount of additives excluding inorganic fillers (F) should not exceed 7 wt%, more preferably should not exceed 5 wt%, such as not exceed 3 wt% .

Therefore, based on the total weight of the heterophasic propylene copolymer (HECO), the heterophasic propylene copolymer (HECO) preferably comprises

(a) less than 75.0% by weight, more preferably 50.0% to 70.0% by weight, still more preferably 60.0% to 65.0% by weight of matrix (M), i.e. polypropylene (PP), and

(b) equal to or greater than 20.0% by weight, more preferably 20.0% to 50.0% by weight, still more preferably 25.0% to 40.0% by weight of elastomer (E),

(c) Up to 8% by weight, more preferably 0 to 8% by weight, such as in the range of 1 to 8% by weight, still more preferably in the range of 0 to 6% by weight polyethylene (PE), preferably high density polyethylene Vinyl (HDPE),

(d) up to 25% by weight, more preferably 4% to 25% by weight, still more preferably 5% to 20% by weight of inorganic filler (F), preferably talc.

Articles made from heterophasic propylene copolymers (HECO)

The inventive heterophasic propylene copolymer (HECO) is preferably used for the production of automotive articles, such as automotive molded articles, preferably automotive injection molded articles. Even more preferably for the production of automotive interior and exterior articles, such as bumpers, side trims, pedal assist, body panels, spoilers, instrument panels, interior trim, etc., especially bumpers.

The present invention also provides (motor vehicle) articles, such as injection molded articles, comprising at least 60% by weight, more preferably at least 70% by weight, still more preferably at least 75% by weight of the inventive heterophasic propylene copolymer (HECO), Such as consisting of the heterophasic propylene copolymer (HECO) of the present invention. Accordingly, the present invention relates in particular to motor vehicle articles, in particular to automotive interior and exterior articles, such as bumpers, side trims, pedal assist devices, body panels, spoilers, instrument panels, interior trim, etc., especially insurance Bars comprising at least 60 wt%, more preferably at least 70 wt%, even more preferably at least 75 wt% of the heterophasic propylene copolymer (HECO) of the invention, such as consisting of the heterophasic propylene copolymer (HECO) of the invention.

Use according to the invention

The present invention also relates to the use of the heterophasic propylene copolymer (HECO) as described above in automotive applications. In a preferred embodiment the heterophasic propylene copolymer (HECO) is used in bumpers.

The present invention will now be described in more detail by the examples provided hereinafter.

Preparation of heterophasic propylene copolymer (HECO)

The heterophasic propylene copolymer (HECO) as defined above may be prepared by the process as defined below.

The heterophasic propylene copolymer (HECO) according to the present invention can be prepared by a process comprising the step of blending the elastomer (E) with the matrix (M). The term "blending" refers according to the invention to the act of providing a blend of at least two different already existing substances. On the other hand, the term "mixing" includes blending, but also includes forming a blend in situ by reacting one species in the presence of the other.

The process according to the invention may also comprise the step of blending one polypropylene fraction selected from (PP1), (PP2) and (PP3) with a mixture comprising the remaining two polypropylene fractions to obtain polypropylene (PP). In another embodiment, a process for the preparation of polypropylene (PP) comprises the step of: (a) combining a polypropylene fraction selected from (PP1), (PP2) and (PP3) with a polypropylene fraction selected from (PP1) , (PP2) and another different polypropylene fraction blended with (PP3) and then adding the remainder selected from (PP1), (PP2) and (PP3), or (b) blending the polypropylene in one step Parts (PP1), (PP2) and (PP3) are blended with each other. The individual polypropylene fractions (PP1), (PP2) and (PP3) can be produced in a conventional manner, eg in a loop reactor or in a loop/gas phase reactor system.

In another embodiment, the present invention relates to a sequential polymerization process for the preparation of polypropylene (PP) according to the present invention, said polypropylene (PP) comprising a first polypropylene fraction (PP1), a second polypropylene part (PP2) and a third polypropylene part (PP3). The method may include the steps of:

(a1) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a first polypropylene fraction (PP1),

(b1) transferring said first polypropylene fraction (PP1) to a second reactor (R2),

(c1) in said second reactor (R2) and in the presence of said first polypropylene fraction (PP1), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a second polypropylene fraction (PP2), said first polypropylene fraction (PP1) being blended with said second polypropylene fraction (PP2),

(d1) transferring the mixture of step (c1) to a third reactor (R3),

(e1) in said third reactor (R3) and in the presence of the mixture obtained in step (c1), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a third polypropylene fraction (PP3), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP);

or

(a2) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a first polypropylene fraction (PP1),

(b2) transferring said first polypropylene fraction (PP1) to a second reactor (R2),

(c2) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha in said second reactor (R2) and in the presence of said first polypropylene fraction (PP1) - polymerisation of olefins to obtain a third polypropylene fraction (PP3), said first polypropylene fraction (PP1) being blended with said third polypropylene fraction (PP3),

(d2) transferring the mixture of step (c2) to a third reactor (R3),

(e2) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha- Polymerization of olefins to obtain a second polypropylene fraction (PP2), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP);

or

(a3) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a second polypropylene fraction (PP2),

(b3) transferring said second polypropylene fraction (PP2) into a second reactor (R2),

(c3) in said second reactor (R2) and in the presence of said second polypropylene fraction (PP2), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a third polypropylene fraction (PP3), said second polypropylene fraction (PP2) being blended with said third polypropylene fraction (PP3),

(d3) transferring the mixture of step (c3) to a third reactor (R3),

(e3) in said third reactor (R3) and in the presence of the mixture obtained in step (c3), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a first polypropylene fraction (PP1), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP);

or

(a4) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a second polypropylene fraction (PP2),

(b4) transferring said second polypropylene fraction (PP2) into a second reactor (R2),

(c4) in said second reactor (R2) and in the presence of said second polypropylene fraction (PP2), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a first polypropylene fraction (PP1), said second polypropylene fraction (PP2) being blended with said first polypropylene fraction (PP1),

(d4) transferring the mixture of step (c4) to a third reactor (R3),

(e4) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha- Polymerization of olefins to obtain a third polypropylene fraction (PP3), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP);

or

(a5) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a third polypropylene fraction (PP3),

(b5) transferring said third polypropylene fraction (PP3) to a second reactor (R2),

(c5) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha in said second reactor (R2) and in the presence of said third polypropylene fraction (PP3) - polymerisation of olefins to obtain a first polypropylene fraction (PP1), said third polypropylene fraction (PP3) being blended with said first polypropylene fraction (PP1),

(d5) transferring the mixture of step (c5) to a third reactor (R3),

(e5) in said third reactor (R3) and in the presence of the mixture obtained in step (c5), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a second polypropylene fraction (PP2), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP);

or

(a6) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a third polypropylene fraction (PP3),

(b6) transferring said third polypropylene fraction (PP3) to a second reactor (R2),

(c6) in said second reactor (R2) and in the presence of said third polypropylene fraction (PP3), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a second polypropylene fraction (PP2), said third polypropylene fraction (PP3) being blended with said second polypropylene fraction (PP2),

(d6) transferring the mixture of step (c6) to a third reactor (R3),

(e6) in said third reactor (R3) and in the presence of the mixture obtained in step (c6), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a first polypropylene fraction (PP1), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP).

Preferably, between the second reactor (R2) and the third reactor (R3), the comonomer is flashed off.

For preferred embodiments of the polypropylene (PP), the first polypropylene fraction (PP1 ), the second polypropylene fraction (PP2) and the third polypropylene fraction (PP3), reference is made to the definitions given above.

The term "sequential polymerisation process" means that polypropylene is produced in at least three reactors connected in series. Therefore, the process comprises at least a first reactor (R1), a second reactor (R2) and a third reactor (R3). The term "polymerization reactor" shall mean where the main polymerization takes place. Thus, if the process consists of four polymerisation reactors, this definition does not exclude the option that the entire process comprises, for example, a prepolymerization step in a prepolymerization reactor. The term "consisting of" is only a closed form with respect to the main polymerization reactor.

The first reactor (R1) is preferably a slurry reactor (SR) and may be any continuous or simply stirred batch tank reactor or loop reactor operated in bulk or slurry. Bulk means polymerization in a reaction medium comprising at least 60% (w/w) monomer. According to the invention, the slurry reactor (SR) is preferably a (bulk) loop reactor (LR).

The second reactor (R2) and the third reactor (R3) are preferably gas phase reactors (GPR). Such gas phase reactors (GPRs) may be any mechanically stirred reactors or fluidized bed reactors. Preferably, the gas phase reactor (GPR) comprises a mechanically agitated fluidized bed reactor with a gas velocity of at least 0.2 m/s. It will thus be appreciated that the gas phase reactor is a fluidized bed type reactor, preferably with a mechanical stirrer.

Therefore, in a preferred embodiment, the first reactor (R1) is a slurry reactor (SR), such as a loop reactor (LR), while the second reactor (R2) and the third reactor (R3 ) is a gas phase reactor (GPR). Therefore, for the present process at least three, preferably three polymerization reactors connected in series are used, i.e. a slurry reactor (SR), such as a loop reactor (LR), a first gas phase reactor (GPR-1), and a second gas phase reactor (GPR-2). A pre-polymerization reactor is placed before the slurry reactor (SR) as required.

技术)，例如在专利文献中，如EP0887379、WO92/12182WO2004/000899、WO2004/111095、WO99/24478、WO99/24479或WO00/68315中所描述的。A preferred multi-stage process is the "loop-gas phase" process, such as that developed by Borealis A/S of Denmark (known as

technology), for example in the patent literature, as described in EP0887379, WO92/12182 WO2004/000899, WO2004/111095, WO99/24478, WO99/24479 or WO00/68315.

方法。Another suitable slurry-gas phase method is Basell's

method.

Preferably, in the process of the present invention for the preparation of polypropylene (PP) as defined above, the first reactor (R1) of step (a), i.e. the slurry reactor (SR), such as a loop reactor The conditions for (LR) can be as follows:

- a temperature in the range of 50°C to 110°C, preferably between 60°C and 100°C, more preferably between 68°C and 95°C,

- a pressure in the range of 20 bar to 80 bar, preferably between 40 bar and 70 bar,

- Hydrogen can be added for molar mass control in a manner known per se.

The reaction mixture from step (a) is then transferred to a second reactor (R2), i.e. gas phase reactor (GPR-1), i.e. transferred to step (c), while the conditions in step (c) are preferably as follows:

- a temperature in the range of 50°C to 130°C, preferably between 60°C and 100°C,

- a pressure in the range of 5 bar to 50 bar, preferably between 15 bar and 35 bar,

- Hydrogen can be added for molar mass control in a manner known per se.

The conditions in the third reactor (R3), preferably the second gas phase reactor (GPR-2) are similar to those of the second reactor (R2).

Residence times can vary in the three reactor zones.

In one embodiment of the process for the preparation of polypropylene, the residence time in the bulk reactor, such as the loop reactor, is in the range of 0.1 hours to 2.5 hours, such as 0.15 hours to 1.5 hours, the residence time in the gas phase reactor The time will generally be 0.2 hours to 6.0 hours, such as 0.5 hours to 4.0 hours.

If desired, in a first reactor (R1), i.e. a slurry reactor (SR), such as a loop reactor (LR) in a known manner under supercritical conditions and/or in a gas phase reactor (GPR) ) in condensation mode.

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

In a preferred embodiment, the prepolymerization is carried out as a bulk slurry polymerization in liquid propylene, ie the liquid phase mainly comprises propylene, with small amounts of other reactants and optionally inert components dissolved therein.

The prepolymerization reaction is generally carried out at a temperature of 10°C to 60°C, preferably 15°C to 50°C, more preferably 20°C to 45°C.

The pressure in the prepolymerization reactor is not critical, but must be high enough to maintain the reaction mixture in the liquid phase. Thus, the pressure may be from 20 bar to 100 bar, eg 30 bar to 70 bar.

The catalyst components are preferably introduced in their entirety into the prepolymerization step. However, when the solid catalyst component (i) and the cocatalyst (ii) can be fed separately, it is possible to introduce only a part of the cocatalyst into the prepolymerization stage and the remaining part to the subsequent polymerization stage. Also, in this case, so much cocatalyst has to be introduced into the prepolymerization stage that sufficient polymerization is obtained therein.

It is also possible to add other components to the prepolymerization stage. Thus, hydrogen may be added to the prepolymerization stage to control the molecular weight of the prepolymer, as is known in the art. Additionally, antistatic additives may be used to prevent the particles from sticking to each other or to the reactor walls.

Precise control of prepolymerization conditions and reaction parameters is within the skill of the art.

According to the present invention, polypropylene (PP) is preferably obtained by a multistage polymerization process as described above in the presence of a catalyst system comprising a Ziegler-Natta procatalyst as component (i), The Ziegler-Natta procatalyst contains transesterification products of lower alcohols and phthalates.

The procatalyst used according to the present invention is prepared by the following steps

a) Reaction of spray crystallized or emulsion solidified adducts of _MgCl2 and _C1 to _C2 alcohols with _TiCl4

b) subjecting the product of stage a) to the phthalic acid of the formula (I) under conditions such that the C _{to C} alcohol is transesterified with a dialkyl phthalate of the formula (I) Dialkyl esters react to form internal donors

wherein R ^1' and R ^2' are independently at least C ₅ alkyl

c) the product of cleaning stage b), or

d) optionally reacting the product of step c) with further _TiCl4 .

Procatalysts are prepared as defined, for example, in patent applications WO87/07620, WO92/19653, WO92/19658 and EP0491566. The contents of these documents are incorporated herein by reference.

Adducts of _MgCl2 and _C1 to _C2 alcohols of the formula _MgCl2 *nROH, where R is methyl or ethyl and n is 1 to 6, are first formed. Ethanol is preferably used as alcohol.

Adducts which first melt and then spray crystallize or emulsion solidify are used as catalyst supports.

In a next step, the spray crystallized or emulsion solidified adduct of the formula _MgCl2 *nROH, where R is methyl or ethyl, preferably ethyl and n is 1 to 6, is contacted with _TiCl4 to form a titanated support, and then is the following steps

· Addition of the following to the titanated support to form the first product

(i) dialkyl phthalates of formula (I), wherein R ¹ ' and R ² ' are independently at least C ₅ alkyl, such as at least C ₈ alkyl,

or preferably

(ii) dialkyl phthalates of formula (I), wherein R ^1' and R ^2' are identical and are at least C ₅ alkyl, such as at least C ₈ alkyl,

or more preferably

(iii) dialkyl phthalates of formula (I) selected from the group consisting of propylhexyl phthalate (PrHP), dioctyl phthalate (DOP), diisodecyl phthalate ester (DIDP) and ditridecyl phthalate (DTDP), still more preferably the dialkyl phthalate of formula (I) is dioctyl phthalate (DOP) such as Diisooctyl phthalate or di(ethylhexyl)phthalate, especially di(ethylhexyl)phthalate,

Subjecting the first product to suitable transesterification conditions, i.e. to a temperature above 100°C, preferably between 100°C and 150°C, more preferably between 130°C and 150°C, so that the methanol or ethanol transesterification with said ester groups of said dialkyl phthalates of formula (I) to form preferably at least 80 mole %, more preferably at least 90 mole %, most preferably at least 95 mole % of formula ( II) dialkyl phthalates

wherein R ^{and R} are methyl or ethyl, preferably ethyl,

a dialkyl phthalate of formula (II) is an internal donor, and

• Recovering the transesterification product as a procatalyst composition (component (i)).

The adduct of formula _MgCl2 *nROH (wherein R is methyl or ethyl and n is 1 to 6) is melted in a preferred embodiment and the melt is then injected, preferably by gas, into a cooled solvent or a cooled gas , whereby the adduct crystallizes in a morphologically favorable form, as described, for example, in WO 87/07620.

As described in WO92/19658 and WO92/19653, this crystalline adduct is preferably used as a catalyst support and reacted as a procatalyst which can be used in the present invention.

When the catalyst residues were removed by extraction, adducts of titanated supports and internal donors were obtained in which the groups derived from the ester alcohols were changed.

If sufficient titanium remains on the support, it will act as the active element of the procatalyst.

Otherwise titanation is repeated after the above treatment to ensure sufficient titanium concentration and thus activity.

Preferably, the procatalyst used according to the invention contains at most 2.5% by weight, preferably at most 2.2% by weight, more preferably at most 2.0% by weight of titanium. Its donor content is preferably between 4% and 12% by weight, more preferably between 6% and 10% by weight.

More preferably, the procatalyst used according to the invention has been prepared by using ethanol as alcohol and dioctyl phthalate (DOP) as dialkyl phthalate of formula (I), resulting in phthalic acid Diethyl ester (DEP) was used as an internal donor compound.

Still more preferably, the catalyst used according to the invention is the BCF20P catalyst of Borealis (prepared according to WO92/19653 as disclosed in WO99/24479; especially according to WO92/19658 using dioctylphthalate as formula (I) dialkyl phthalates) or catalyst Polytrack 8502 commercially available from Grace.

For the preparation of the polypropylene (PP) according to the invention, the catalyst system used preferably comprises, in addition to the specific Ziegler-Natta procatalyst, an organometallic cocatalyst as component (ii).

Accordingly, the cocatalyst is preferably selected from trialkylaluminums such as triethylaluminum (TEA), dialkylaluminum chlorides and alkylaluminum sesquichlorides.

Component (iii) of the catalyst system used is an external donor represented by formula (IIIa) or (IIIb). Formula (IIIa) is defined by

Si(OCH ₃ ) ₂ R ₂ ⁵ (IIIa)

wherein ^R represents a branched alkyl group having 3 to 12 carbon atoms, preferably a branched alkyl group having 3 to 6 carbon atoms, or a cycloalkyl group having 4 to 12 carbon atoms, preferably having 5 to 6 carbon atoms A cycloalkyl group of 8 carbon atoms.

Particularly preferably, R ^is selected from isopropyl, isobutyl, isopentyl, tert-butyl, tert-pentyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

Formula (IIIb) is defined by

Si(OCH ₂ CH ₃ ) ₃ (NR ^x R ^y )(IIIb)

wherein R ^x and R ^y may be the same or different, and represent a hydrocarbon group having 1 to 12 carbon atoms.

^Rx and ^Ry are independently selected from linear aliphatic hydrocarbon groups having 1 to 12 carbon atoms, branched aliphatic hydrocarbon groups having 1 to 12 carbon atoms, and cyclic aliphatic hydrocarbon groups having 1 to 12 carbon atoms. Particularly preferably, ^Rx and ^Ry are independently selected from methyl, ethyl, n-propyl, n-butyl, octyl, decyl, isopropyl, isobutyl, isopentyl, tert-butyl, tert- Pentyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

More preferably, ^Rx and ^Ry are the same, still more preferably, ^{both Rx} and ^Ry are ethyl.

More preferably, the external donor of formula (IIIb) is diethylaminotriethoxysilane.

More preferably, the external donor is selected from diethylaminotriethoxysilane [Si(OCH ₂ CH ₃ ) ₃ (N(CH ₂ CH ₃ ) ₂ )], dicyclopentyldimethoxysilane [Si( OCH ₃ ) ₂ (cyclopentyl) ₂ ], diisopropyldimethoxysilane [Si(OCH ₃ ) ₂ (CH(CH ₃ ) ₂ ) ₂ ] and mixtures thereof.

In another embodiment, the Ziegler-Natta procatalyst can be modified by polymerizing vinyl compounds in the presence of a catalyst system comprising a specific Ziegler-Natta procatalyst (component (i)), an external donor (component (iii)) and optionally a cocatalyst (component (iii)), the vinyl compound having the following formula:

CH ₂ =CH-CHR ³ R ⁴

wherein ^R3 and ^R4 together form a 5-membered or 6-membered saturated, unsaturated or aromatic ring, or independently represent an alkyl group containing 1 to 4 carbon atoms, the modified catalyst is used to prepare the Heterophasic propylene copolymer. Polymerized vinyl compounds can act as α-nucleating agents.

Regarding the modification of the catalyst, reference is made to the International Applications WO99/24478, WO99/24479 and especially WO00/68315, incorporated herein by reference with respect to the reaction conditions for the modification of the catalyst as well as in the polymerization reaction.

The obtained polypropylene (PP) is then blended with the elastomer (E) and optional additives. Extruders such as single-screw extruders and twin-screw extruders are generally used for blending. Other suitable devices include planetary extruders and single screw co-kneaders. Especially preferred are twin-screw extruders comprising a high intensity mixing section and a kneading section. Suitable melt temperatures for the preparation of the heterophasic propylene copolymer (HECO) are in the range of 170°C to 300°C, preferably in the range of 200°C to 260°C. The heterophasic propylene copolymer (HECO) recovered from the extruder is usually in the form of pellets. These pellets are then preferably further processed, for example by injection moulding, to obtain articles, as defined in more detail above.

The present invention will be further illustrated below by way of examples.

Example

A. Measurement method

Unless otherwise defined, the following definitions of terms and assay methods apply to the above general description of the invention as well as to the following examples.

Calculation of the comonomer content of the second polypropylene fraction (PP2):

$\frac{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; xC</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

in

w(PP1) is the weight fraction of the first polypropylene fraction (PP1), i.e. the product of the first reactor (R1),

w(PP2) is the weight fraction of the second polypropylene fraction (PP2), i.e. the polymer produced in the second reactor (R2),

C(PP1) is the comonomer content [% by weight] of the first polypropylene fraction (PP1), i.e. the product of the first reactor (R1),

C(R2) is the comonomer content [% by weight] of the product obtained in the second reactor (R2), i.e. the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2),

C(PP2) is the calculated comonomer content [% by weight] of the second polypropylene (PP2).

Calculation of the xylene cold soluble (XCS) content of the second polypropylene fraction (PP2):

$\frac{\mathrm{<span\; class="notranslate">\; XS</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; wxya</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; XS</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

in

w(PP1) is the weight fraction of the first polypropylene fraction (PP1), i.e. the product of the first reactor (R1),

w(PP2) is the weight fraction of the second polypropylene fraction (PP2), i.e. the polymer produced in the second reactor (R2),

XS(PP1) is the xylene cold soluble (XCS) content [% by weight] of the first polypropylene fraction (PP1), i.e. the product of the first reactor (R1),

XS(R2) is the xylene cold soluble (XCS) content of the product obtained in the second reactor (R2), i.e. the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2) [weight%],

XS(PP2) is the calculated xylene cold soluble (XCS) content [% by weight] of the second polypropylene fraction (PP2).

Calculation of the melt flow rate MFR ₂ (230°C) of the second polypropylene fraction (PP2):

$\mathrm{<span\; class="notranslate">\; MFR</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; MFR</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; MFR</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>}$

in

w(PP1) is the weight fraction of the first polypropylene fraction (PP1), i.e. the product of the first reactor (R1),

w(PP2) is the weight fraction of the second polypropylene fraction (PP2), i.e. the polymer produced in the second reactor (R2),

MFR(PP1) is the melt flow rate _MFR2 (230°C) [g/10min] of the first polypropylene fraction (PP1), i.e. the product of the first reactor (R1),

MFR(R2) is the melt flow rate _MFR2 (230°C) of the product obtained in the second reactor (R2), i.e. the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2) [g/10min],

MFR(PP2) is the calculated melt flow rate MFR ₂ (230° C.) [g/10 min] of the second polypropylene fraction (PP2).

Calculation of the comonomer content of the third polypropylene fraction (PP3):

$\frac{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; xC</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

in

w(R2) is the product of the second reactor (R2), i.e. the weight fraction of the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2),

w(PP3) is the weight fraction of the third polypropylene fraction (PP3), i.e. the polymer produced in the third reactor (R3),

C(R2) is the comonomer content [% by weight] of the product of the second reactor (R2), i.e. the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2),

C(R3) is the product obtained in the third reactor (R3), i.e. the copolymerization of a mixture of the first polypropylene fraction (PP1), the second polypropylene fraction (PP2) and the third polypropylene fraction (PP3) monomer content [wt%],

C(PP3) is the calculated comonomer content [% by weight] of the third polypropylene fraction (PP2).

Calculation of the xylene cold soluble (XCS) content of the third polypropylene fraction (PP3):

$\frac{\mathrm{<span\; class="notranslate">\; XS</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; wxya</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; XS</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

in

w(R2) is the product of the second reactor (R2), i.e. the weight fraction of the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2),

w(PP3) is the weight fraction of the polymer produced in the third polypropylene fraction (PP3), i.e. the third reactor (R3),

XS(R2) is the xylene cold soluble (XCS) content [% by weight] of the product of the second reactor (R2), i.e. the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2) ,

XS(R3) is the product obtained in the third reactor (R3), i.e. two fractions of the mixture of the first polypropylene fraction (PP1), the second polypropylene fraction (PP2) and the third polypropylene fraction (PP3). Toluene cold soluble (XCS) content [% by weight],

XS(PP3) is the calculated xylene cold soluble (XCS) content [% by weight] of the third polypropylene fraction (PP3).

Calculate the melt flow rate MFR ₂ (230°C) of the third polypropylene fraction (PP3):

$\mathrm{<span\; class="notranslate">\; MFR</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; MFR</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; MFR</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; PP</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>}$

in

w(R2) is the product of the second reactor (R2), i.e. the weight fraction of the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2),

w(PP3) is the weight fraction of the third polypropylene fraction (PP3), i.e. the polymer produced in the third reactor (R3),

MFR(R2) is the melt flow rate MFR ₂ (230°C) [g/10] of the product of the second reactor (R2), i.e. the mixture of the first polypropylene fraction (PP1) and the second polypropylene fraction (PP2) minute],

MFR (R3) is the product obtained in the third reactor (R3), i.e. the melt of the mixture of the first polypropylene fraction (PP1), the second polypropylene fraction (PP2) and the third polypropylene fraction (PP3) Bulk flow rate MFR ₂ (230°C) [g/10min],

MFR(PP3) is the calculated melt flow rate _MFR2 (230°C) [g/10min] of the third polypropylene fraction (PP3).

Number average molecular weight ( _Mn ), weight average molecular weight ( _Mw ) and molecular weight distribution (MWD) were determined by gel permeation chromatography (GPC) according to the following methods:

The weight average molecular weight Mw and the molecular weight distribution (MWD=Mw/Mn, where Mn is the number average molecular weight and Mw is the weight average molecular weight) are measured by a method based on ISO16014-1:2003 and ISO16014-4:2003. Waters Alliance GPCV2000 equipped with refractive index detector and online viscometer adopts 3x TSK-gel column (GMHXL-HT) of TosoHaas and 1,2,4-trichlorobenzene (TCB, with 200mg/L2,6-ditertiary Butyl-4-methyl-phenol stabilized) was used as solvent at a constant flow rate of 1 mL/min at 145°C. 216.5 μL of sample solution was injected per analysis. The column set was calibrated with a relative scale with 19 narrow MWD polystyrene (PS) standards ranging from 0.5 kg/mole to 11500 kg/mole and a set of well characterized broad polypropylene standards. All samples were prepared by dissolving 5 mg to 10 mg of polymer in 10 mL (at 160° C.) of stabilized TCB (same as the mobile phase) and kept under continuous shaking for 3 hours before being injected into the GPC instrument.

Density is measured according to ISO 1183-1 - Method A (2004). Sample preparation was done by compression molding according to ISO1872-2:2007.

MFR ₂ (230° C.) is measured according to ISO1133 (230° C., 2.16 kg load).

MFR ₂ (190° C.) is measured according to ISO1133 (190° C., 2.16 kg load).

Comonomer content quantification by FTIR spectroscopy

Comonomer content was determined by quantitative Fourier Transform Infrared Spectroscopy (FTIR) after base assignment calibrated by ^{quantitative13C} Nuclear Magnetic Resonance (NMR) spectroscopy in a manner well known in the art. Films were pressed to a thickness between 100 μm and 500 μm and spectra were recorded in transmission mode.

Specifically, the ethylene content of the propylene-ethylene copolymer was determined using the baseline-corrected peak areas of the quantitative bands found at 720 cm ⁻¹ to 722 cm ⁻¹ and 730 cm ⁻¹ to 733 cm ⁻¹ . Specifically, the butene or hexene content of polyethylene copolymers was determined using the baseline corrected peak area of the quantitative band found at 1377 cm ⁻¹ to 1379 cm ⁻¹ . Quantitative results were obtained based on a reference film thickness.

Xylene cold solubles (XCS, weight %): The content of xylene cold solubles (XCS) is determined at 25° C. according to ISO 16152: First Edition; 2005-07-01.

Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in decalin at 135°C).

Melting temperature T _m , crystallization temperature T _c were measured using a Mettler TA820 differential scanning calorimeter (DSC) with 5 mg to 10 mg samples. Both crystallization and melting curves were obtained during cooling and heating scans between 30°C and 225°C at 10°C/min. Melting and crystallization temperatures were taken as endothermic and exothermic peaks.

Melting enthalpy and crystallization enthalpy (Hm and Hc) were also measured by DSC method according to ISO11357-3.

Tensile modulus is according to ISO527-1 (crosshead speed = 1mm/min) at 23°C using injection molded test pieces according to ISO527-2(1B) manufactured according to EN ISO1873-2 (dog bone shape 10, thickness 4mm) measured.

Charpy notched impact strength was determined according to ISO179/1eA at 23°C and at -20°C by using injection molded test specimens (80x10x4mm) as described in EN ISO1873-2.

The puncture energy was determined with the Instrumented Falling Weight (IFW) test according to ISO 6603-2 using injection molded parts of 60 x 60 x 2 mm and a test speed of 4.4 m/s. The reported piercing energies are obtained from the integration of the failure energy curves measured at +23°C and -20°C.

Shrinkage was determined on a center-gated injection molded disc (diameter 180 mm, thickness 3 mm, with a flow angle of 355° and a cut-off angle of 5°). Two specimens were molded applying two different holding pressure times (10 s and 20 s, respectively). The melt temperature at the gate was 260 °C and the average flow front velocity in the mold was 100 mm/s. Tool temperature: 40°C, counter pressure: 600 bar.

After conditioning the samples for 96 hours at room temperature, the radial and tangential dimensional changes with respect to the direction of flow were measured for both discs. The average of the respective values from the two disks is reported as the final result.

The particle size (d50 and cutoff d95 (sedimentation)) is calculated from the particle size distribution [mass percent] determined by gravitational liquid sedimentation (sedimentation diagram) according to ISO 13317-3.

BET has been measured according to ISO9277.

B. Example

All polymers were produced in a Borstar pilot plant with a prepolymerization reactor, a slurry loop reactor and two gas phase reactors. Catalyst Polytrack 8502 commercially available from Grace (US) with diethylaminotriethoxysilane [Si(OCH ₂ CH ₃ ) ₃ (N(CH ₂ CH ₃ ) ₂ )] (U donor) and Triethylaluminum (TEAL) as an activator and scavenger was used in combination in the proportions shown in Table 1. The catalyst is modified by polymerizing vinyl compounds in the presence of the catalyst system.

Table 1: Preparation of Polypropylene (PP)

parameter unit H-PP Donor type u Al/donor ratio [mol/mol] 9 Ring MFR ₂ (230°C) [g/10min] 343 XCS [weight%] 2.1 GPR1 MFR ₂ (230°C) [g/10min] 218 XCS [weight%] 2.0 MFR ₂ * [g/10min] 134 XCS* [weight%] 1.8 GPR2 MFR ₂ (230°C) [g/10min] 125 XCS [weight%] 1.8 MFR ₂ ** [g/10min] 6.5 XCS** [weight%] 1.5 MWD [-] 6.5 Distribution Ring/GPR1/GPR2 [weight%] 42/42/16

* Polymer prepared in GPR1

** Polymer prepared in GPR2

Table 1 summarizes the polymer design of the trimodal polypropylene used in the working examples. A trimodal polypropylene (PP) having the same MFR as a commercially available unimodal polypropylene polymer (HK060AE) was used.

Table 2: Compound formulations for working examples and comparative examples

components E1 E2 E3 CE1 CE2 HK060AE - - - 67.1 53.7 H-PP 67.1 67.1 53.7 - - Engage8400 30 25 twenty four 30 twenty four HDPE - 5 - - - Talcum - - 20 - 20

The remainder to 100% by weight are additives such as antioxidants and pigments (e.g. carbon black)

HK060AE is a commercial product of Borealis AG, which is a polypropylene homopolymer with a MFR ₂ (230° C./2.16 kg) of 125 g/10 min and a density of 905 kg/m ³ .

Engage 8400 is a commercial product from Dow Elastomers, which is an ethylene-octene copolymer with a MFR ₂ (190°C, 2.16 kg) of 30 g/10 min and a density of 870 kg/m ³ .

HDPE is a commercial high density polyethylene (HDPE) "MG9601" of Borealis having an MFR (190°C/2.16kg) of 30 g/10 min and a density of 960 kg/ ^m3 .

Talcum is a commercial talc "Steamic T1CA" available from Luzenac with a d50 of 1.8 μm, a cut-off particle size (d ₉₅ ) of 6.2 μm and a BET of 8.0 m ² /g.

The performance characteristics of the resulting materials are summarized in Table 3.

Table 3: Performance characteristics of polypropylene elastomer blends

components unit E1 E2 E3 CE1 CE2 MFR ₂ (230°C) [g/10min] 92 100 80 86 75 Tensile modulus [MPa] 1330 1450 1860 1060 1680 Impact strength +23℃ [kJ/m ² ] 5.2 4.1 4.0 4.1 4.5 Impact strength -20℃ [kJ/m ² ] 2.0 1.6 2.0 2.0 2.0 Piercing Energy +23°C [J] 19 18 12 6 12 Puncture Energy -20°C [J] 10 9 4 1.3 4 Radial shrinkage [%] 1.0 1.3 0.9 1.1 0.9 Tangential shrinkage [%] 1.1 1.4 0.9 1.1 1.0

Although the working and comparative examples show similar melt flow rates, the working examples based on trimodal polypropylene according to the invention show significantly improved stiffness levels and slightly improved Charpy impact strength at room temperature. It is even more evident that the puncture energy is improved by using a trimodal matrix, the puncture energy of the blend with the elastomer being more than three times that of the commercial reference.

Claims (16)

1. A heterophasic propylene copolymer (HECO) comprising (a) is a matrix (M) of polypropylene (PP) comprising at least three polypropylene fractions (PP1), (PP2) and (PP3), said three polypropylene fractions (PP1 ), (PP2) and (PP3) differ from each other in the melt flow rate MFR ₂ (230° C.) measured according to ISO1133, and (b) an elastomer (E) dispersed in said matrix (M), wherein said elastomer (E) is comprised in an amount of 20% by weight or more based on the weight of said heterophasic propylene copolymer (HECO) . 2. The heterophasic propylene copolymer (HECO) according to claim 1, wherein the heterophasic propylene copolymer (HECO) has a melt flow rate _MFR2 (230 ℃). 3. The heterophasic propylene copolymer (HECO) according to claim 1 or 2, wherein at least one of the polypropylene fractions (PP1), (PP2) and (PP3) is a propylene homopolymer, preferably , wherein at least two of said polypropylene fractions (PP1), (PP2) and (PP3) are propylene homopolymers, more preferably, wherein said polypropylene fractions (PP1), (PP2) and (PP3) Both are propylene homopolymers. 4. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein (a) the first polypropylene fraction (PP1) has a melt flow rate MFR ₂ (230 g/10 min to 500 g/10 min, preferably 250 g/10 min to 450 g/10 min measured according to ISO 1133 °C), and/or (b) the second polypropylene fraction (PP2) has a melt flow rate MFR ₂ (230 g/10 min to 300 g/10 min, preferably 100 g/10 min to 200 g/10 min measured according to ISO 1133 °C), and/or (c) the third polypropylene fraction (PP3) has a melt flow rate MFR ₂ (230 ℃). 5. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein the polypropylene (PP) comprises (a) the first polypropylene fraction (PP1) in an amount of 20.0% to 55% by weight, based on the total weight of said matrix (M), and/or (b) a second polypropylene fraction (PP2) in an amount of 20% to 55% by weight, based on the total weight of said matrix (M), and/or (c) A third polypropylene fraction (PP3) in an amount of 10% to 30% by weight, based on the total weight of said matrix (M). 6. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein the elastomer (E) (a) has a melt flow rate MFR ₂ (190° C.) measured according to ISO 1133 of 10 g/10 min to 80 g/10 min, and/or (b) have an intrinsic viscosity of 0.7dl/g to 2.5dl/g, and/or (c) is comprised in said heterophasic propylene copolymer (HECO) in an amount of 20% to 50% by weight, based on the total weight of said heterophasic propylene copolymer (HECO), and/or (d) has a density of less than 940 kg/m ³ . 7. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein the elastomer (E) is an ethylene copolymer elastomer comprising ethylene monomer units and comonomer units, wherein the The comonomers are selected from _C3 to _C20 alpha-olefins, preferably propylene, 1-butene, 1-hexene and 1-octene; or _C5 to _C20 alpha, omega-dienes, preferably Wherein the comonomer is selected from propylene, 1-butene, 1-hexene, 1-octene and 1,7-octadiene. 8. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein the polypropylene (PP) has a xylene cold soluble (XCS) fraction equal to or less than 3.5% by weight. 9. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein each of the three polypropylene fractions (PP1), (PP2) and (PP3) has a A xylene cold soluble (XCS) content of less than 4.0% by weight. 10. The heterophasic propylene copolymer (HECO) according to any one of the preceding claims, wherein the heterophasic propylene copolymer (HECO) further comprises (a) High-density polyethylene (HDPE) and / or (b) Inorganic filler (F). 11. A process for the preparation of a heterophasic propylene copolymer (HECO) according to any one of the preceding claims, comprising the steps of: The matrix (M) is blended with the elastomer (E) and optionally high density polyethylene (HDPE) and inorganic filler (F). 12. Process for preparing heterophasic propylene copolymer (HECO) according to claim 11, further comprising the step of: One polypropylene fraction selected from (PP1), (PP2) and (PP3) is blended with a mixture containing the remaining two polypropylene fractions. 13. Process for preparing heterophasic propylene copolymer (HECO) according to claim 11 or 12, further comprising the step of: (a) blending one polypropylene fraction selected from (PP1), (PP2) and (PP3) with another different polypropylene fraction selected from (PP1), (PP2) and (PP3), then Add the remainder of (PP1), (PP2) and (PP3), or (b) Blending said polypropylene fractions (PP1), (PP2) and (PP3) with each other. 14. Process for preparing heterophasic propylene copolymer (HECO) according to claim 12, further comprising the step of: (a1) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a first polypropylene fraction (PP1), (b1) transferring said first polypropylene fraction (PP1) to a second reactor (R2), (c1) in said second reactor (R2) and in the presence of said first polypropylene fraction (PP1), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a second polypropylene fraction (PP2), said first polypropylene fraction (PP1) being blended with said second polypropylene fraction (PP2), (d1) transferring the mixture of step (c1) to a third reactor (R3), (e1) in said third reactor (R3) and in the presence of the mixture obtained in step (c1), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a third polypropylene fraction (PP3), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP); or (a2) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a first polypropylene fraction (PP1), (b2) transferring said first polypropylene fraction (PP1) to a second reactor (R2), (c2) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha in said second reactor (R2) and in the presence of said first polypropylene fraction (PP1) - polymerisation of olefins to obtain a third polypropylene fraction (PP3), said first polypropylene fraction (PP1) being blended with said third polypropylene fraction (PP3), (d2) transferring the mixture of step (c2) to a third reactor (R3), (e2) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha- Polymerization of olefins to obtain a second polypropylene fraction (PP2), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP); or (a3) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a second polypropylene fraction (PP2), (b3) transferring said second polypropylene fraction (PP2) into a second reactor (R2), (c3) in said second reactor (R2) and in the presence of said second polypropylene fraction (PP2), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a third polypropylene fraction (PP3), said second polypropylene fraction (PP2) being blended with said third polypropylene fraction (PP3), (d3) transferring the mixture of step (c3) to a third reactor (R3), (e3) in said third reactor (R3) and in the presence of the mixture obtained in step (c3), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a first polypropylene fraction (PP1), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP); or (a4) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a second polypropylene fraction (PP2), (b4) transferring said second polypropylene fraction (PP2) into a second reactor (R2), (c4) in said second reactor (R2) and in the presence of said second polypropylene fraction (PP2), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a first polypropylene fraction (PP1), said second polypropylene fraction (PP2) being blended with said first polypropylene fraction (PP1), (d4) transferring the mixture of step (c4) to a third reactor (R3), (e4) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha- Polymerization of olefins to obtain a third polypropylene fraction (PP3), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP); or (a5) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a third polypropylene fraction (PP3), (b5) transferring said third polypropylene fraction (PP3) to a second reactor (R2), (c5) propylene and optionally at least one ethylene and/or _C4 to _C12 alpha in said second reactor (R2) and in the presence of said third polypropylene fraction (PP3) - polymerisation of olefins to obtain a first polypropylene fraction (PP1), said third polypropylene fraction (PP3) being blended with said first polypropylene fraction (PP1), (d5) transferring the mixture of step (c5) to a third reactor (R3), (e5) in said third reactor (R3) and in the presence of the mixture obtained in step (c5), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a second polypropylene fraction (PP2), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP); or (a6) polymerizing propylene and optionally at least one ethylene and/or _C4 to _C12 alpha-olefin in a first reactor (R1) to obtain a third polypropylene fraction (PP3), (b6) transferring said third polypropylene fraction (PP3) to a second reactor (R2), (c6) in said second reactor (R2) and in the presence of said third polypropylene fraction (PP3), propylene and optionally at least one ethylene and/or _C4 to _C12 alpha - polymerisation of olefins to obtain a second polypropylene fraction (PP2), said third polypropylene fraction (PP3) being blended with said second polypropylene fraction (PP2), (d6) transferring the mixture of step (c6) to a third reactor (R3), (e6) in said third reactor (R3) and in the presence of the mixture obtained in step (c6), propylene and optionally at least one ethylene and/ _or C to C _α- Polymerization of olefins to obtain a first polypropylene fraction (PP1), wherein said first polypropylene fraction (PP1), said second polypropylene fraction (PP2) and said third polypropylene fraction (PP3) are mixed with each other and form polypropylene (PP). 15. An article comprising the heterophasic propylene copolymer (HECO) according to any one of claims 1 to 10. 16. Use of the heterophasic propylene copolymer (HECO) according to any one of claims 1 to 10 in automotive applications.