RU2805309C1 - Translucent polyolefin blends providing excellent balance of impact strength - stiffness and flow - Google Patents

Abstract

FIELD: polymer compositions.

SUBSTANCE: present invention relates to a group of inventions: a heterophasic polypropylene composition for use in automotive products and an injection moulded product. The heterophasic polypropylene composition includes: 60.0-85.0 wt. % of the first heterophasic propylene-ethylene copolymer (HECO1); 5.0-20.0 wt. % of a second heterophasic propylene-ethylene copolymer (HECO2) different from the first heterophasic propylene-ethylene copolymer (HECO1); 5.0-20.0 wt. % ethylene polymer (PE) selected from an ethylene-LDPE based plastomer having a density of 895 to 925 kg/m³. The heterophasic polypropylene composition has a melt flow rate MFR₂ measured in accordance with ISO 1133-1 at 230°C and a load of 2.16 kg, 15.0-40.0 g/10 min, and a soluble fraction (SF) determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount of 5.0-23.0 wt% relative to the total weight of the heterophasic polypropylene composition. The combined amount of the first heterophasic propylene-ethylene copolymer (HECO1), the second heterophasic propylene-ethylene copolymer (HECO2) and ethylene polymer (PE) is greater than or equal to 95 wt% relative to the total weight of the heterophasic polypropylene composition. The injection moulded article contains this heterophasic propylene-ethylene composition.

EFFECT: development of a heterophasic polypropylene composition having an improved balance of stiffness and impact strength, as well as a good overall light transmission coefficient while maintaining favourable properties in other areas, such as workability.

15 cl, 4 tbl, 1 dwg, 6 ex

Description

The present invention relates to a heterophasic polypropylene composition with good overall light transmittance and a good balance of stiffness and impact properties, as well as products made from this composition.

State of the art

Polymers such as polypropylene are increasingly being used in a variety of demanding applications. At the same time, there is a continuous search for specially developed polymers that meet the requirements of these applications. The requirements can be difficult to meet because many properties of polymers are directly or indirectly interrelated, i.e. improvement of a particular property can only be achieved at the expense of another property. For example, stiffness can be improved by increasing crystallinity and/or the relative amount of homopolymer in the composition. As a consequence, the material becomes more brittle, resulting in poor impact properties. It is known that the impact strength of polypropylene can be improved by dispersing a rubber phase in a polymer matrix, thereby obtaining a heterophasic polypropylene composition.

Such heterophasic propylene copolymers contain a matrix of either a propylene homopolymer or a random propylene copolymer in which an amorphous phase containing propylene copolymer rubber (elastomer) is dispersed. Thus, the polypropylene matrix contains (finely) dispersed inclusions that are not part of the matrix, and these inclusions contain an elastomer. The term "inclusion" indicates that the matrix and inclusion form distinct phases in the heterophasic propylene copolymer, said inclusions being, for example, visible by high-resolution microscopy such as electron microscopy, scanning force microscopy or atomic force microscopy.

Heterophasic polypropylene compositions have long been used for automotive applications due to their beneficial mechanical properties, including a favorable stiffness-to-impact ratio (as indicated by Charpy or Izod impact strength and puncture energy). Sensors and light-emitting diodes (LEDs) have been used in cars for many years, but due to new trends such as autonomous driving, more and more sensors will need to be integrated into cars in the near future. For aesthetic reasons, it is desirable that the sensors and/or LEDs are not visible to the naked eye, but the function of the component (either sensing or emitting light) should not be impaired. As such, translucent polypropylene blends have great potential for use in such systems. However, there remains a need for translucent polypropylene compounds that have optimal mechanical properties in addition to suitable optical properties.

There are numerous descriptions of heterophasic polypropylene compositions for use in automobiles, however, the purpose of the present invention, i.e. obtaining a favorable balance of optical (in particular, overall light transmittance) and mechanical properties (in particular, impact strength) has not yet been sufficiently resolved.

WO 2017/117054 A1 describes a mixture of heterophasic propylene-ethylene copolymers with propylene homopolymers to obtain improved haze properties, although no indication is given on the overall light transmittance.

EP 2275485 A1 describes a heterophasic polypropylene composition having improved mechanical properties due, among other things, to the use of 10 wt. % mineral fillers.

EP 2480606 A1 describes a heterophasic polypropylene composition with high melt flow rates and low C2 content.

Brief description of the invention

The present invention is based on the discovery that a heterophasic polypropylene composition (K) containing a first heterophasic propylene-ethylene copolymer (HECO1), a second heterophasic propylene-ethylene copolymer (HECO2) and an ethylene polymer (PE) has an improved balance of stiffness and impact strength, as well as good overall light transmittance while maintaining favorable properties in other areas such as machinability.

The present invention is directed to a heterophasic polypropylene composition (K) containing:

A. from 60.0 to 85.0 wt. % of the first heterophasic propylene-ethylene copolymer (GECO1), having:

i. crystalline fraction (CF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in quantities from 75.0 to 92.0 wt. % relative to the total mass of GESO1;

ii. soluble fraction (RF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in quantities from 8.0 to 25.0 wt. % relative to the total mass of GESO1;

iii. characteristic viscosity of the soluble fraction (CV(RF)) from 2.00 to 4.00 dl/g;

b. from 5.0 to 20.0 wt. % of the second heterophasic propylene-ethylene copolymer (HECO2), different from the first heterophasic propylene-ethylene copolymer (HECO1), and having

i. soluble fraction (RF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 15.0 to 30.0 wt. % relative to the total mass of GESO2;

ii. characteristic viscosity of the soluble fraction (CV(RF)) from 2.5 to 5.0 dl/g, and

c. from 5.0 to 20.0 wt. % ethylene polymer (PE), selected from an ethylene- and LDPE-based plastomer having a density of 895 to 925 kg/m ³ ;

wherein the heterophasic polypropylene composition (K) has a melt flow index PTR ₂ , measured in accordance with ISO 1133-1 at 230°C and a load of 2.16 kg, from 15.0 to 40.0 g/10 min, and a soluble fraction (RF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in quantities from 5.0 to 23.0 wt. % relative to the total weight of the heterophasic polypropylene composition (K), and

the combined amount of the first heterophasic propylene-ethylene copolymer (HECO1), the second heterophasic propylene-ethylene copolymer (HECO2) and the ethylene polymer (PE) is greater than or equal to 95 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

In another aspect, the present invention relates to an injection molded product containing the heterophasic polypropylene composition (K) described above, the injection molded product preferably being an automobile product.

Definitions

By polymer blend we mean a mixture of two or more polymer components. In general, a mixture can be prepared by mixing two or more polymer components. Suitable mixing methods known in the art are in situ mixing during the polymerization process and mixing after polymerization. During in-situ mixing, polymer components produced at different stages of a multi-stage polymerization process are mixed by polymerizing one polymer component in the presence of another polymer component polymerized in a previous stage. The mixtures obtained after polymerization may be dry mixtures of polymer components, such as polymer powders and/or compounded polymer granules, or melt mixtures obtained by melt mixing the polymer components. In the present invention, the polymer mixture is preferably obtained by mixing the polymer components after polymerization.

Heterophasic polypropylene is a propylene-based copolymer with a crystalline matrix phase, which may be a propylene homopolymer or a random copolymer of propylene and at least one alpha-olefin comonomer, and an elastomeric phase dispersed therein. In the case of a random heterophasic propylene copolymer, said crystalline matrix phase is a random copolymer of propylene and at least one alpha-olefin comonomer.

The elastomeric phase may be a propylene copolymer with a large amount of comonomer that is not distributed randomly in the polymer chain, but is distributed in a comonomer-rich block structure and a propylene-rich block structure. Heterophasic polypropylene usually differs from single-phase propylene copolymer in that it exhibits two different glass transition temperatures Tg, which relate to the matrix phase and the elastomeric phase.

A plastomer is a polymer that combines the qualities of elastomers and plastics, such as rubber-like properties with the processability of plastics.

An ethylene-based plastomer is a plastomer containing a majority molar portion of ethylene monomer units.

While low-density polyethylenes (LDPEs) typically have low densities (typically 910 to 940 kg/m ³ ), in the context of the present invention LDPEs are characterized as the result of high-pressure radical polymerization processes, thus having a significantly branched nature, in in contrast to linear low density polyethylenes (LLDPEs), which have the same low density without the branching character due to the use of transition metal polymerization.

Detailed Description of the Invention

The heterophasic polypropylene composition (K) of the present invention contains a first heterophasic propylene-ethylene copolymer (HECO1), a second heterophasic propylene-ethylene copolymer (HECO2) and an ethylene polymer (PE), each of which has the properties specified in the following sections and is present in quantity indicated below.

The first heterophasic propylene-ethylene copolymer (HECO1)

The first heterophasic propylene-ethylene copolymer (HECO1) according to the present invention is present in an amount of 60.0 to 85.0 wt. %, more preferably in an amount from 65.0 to 82.0 wt. %, even more preferably in an amount from 70.0 to 80.0 wt. %, most preferably from 74.0 to 78.0 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

The first heterophasic propylene-ethylene copolymer (HECO1) has a crystalline fraction (CF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 75.0 to 92.0 wt. %, more preferably from 78.0 to 90.0 wt. %, even more preferably from 81.0 to 88.0 wt. %, most preferably from 83.0 to 86.0 wt. %, relative to the total weight of the first heterophasic propylene-ethylene copolymer (GECO1).

The crystalline fraction (CF) of the first heterophasic propylene-ethylene copolymer (HECO1) preferably has an intrinsic viscosity (IV (IV)) of 1.00 to 2.00 dl/g, more preferably 1.10 to 1.80 dl/g, even more preferably 1.20 to 1.60 dl/g, most preferably 1.25 to 1.50 dl/g.

The crystalline fraction (CF) of the first heterophasic propylene-ethylene copolymer (HECO1) preferably has an ethylene content (C2(CF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 0.5 to 5.0 wt. %, more preferably from 1.0 to 4.0 wt. %, even more preferably from 1.3 to 3.0 wt. %, most preferably from 1.5 to 2.0 wt. %.

The first heterophasic propylene-ethylene copolymer (HESO1) has a soluble fraction (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 8.0 to 25.0 wt. %, more preferably from 10.0 to 22.0 wt. %, even more preferably from 12.0 to 19.0 wt. %, most preferably from 14.0 to 17.0 wt. % relative to the total weight of the first heterophasic propylene-ethylene copolymer (GECO1).

The soluble fraction (SF) of the first heterophasic propylene-ethylene copolymer (HECO1) has an intrinsic viscosity (IV(RF)) of 2.00 to 4.00 dl/g, more preferably 2.30 to 3.70 dl/g, more more preferably 2.50 to 3.50 dl/g, most preferably 2.60 to 3.30 dl/g.

The soluble fraction (SF) of the first heterophasic propylene-ethylene copolymer (HECO1) preferably has an ethylene content (C2(RF)), measured by infrared spectroscopy in the CRYSTEX assay, from 20.0 to 60.0 wt. %, more preferably from 25.0 to 50.0 wt. %, even more preferably from 30.0 to 40.0 wt. %, most preferably from 34.0 to 38.0 wt. %.

The ratio of the intrinsic viscosity of the soluble fraction to the intrinsic viscosity of the crystalline fraction (IV(RF)/IV(CP)) of the first heterophasic propylene-ethylene copolymer (HECO1) is preferably from 1.00 to 3.00, more preferably from 1.30 to 2, 70, even more preferably from 1.60 to 2.40, most preferably from 1.80 to 2.20.

The first heterophasic propylene-ethylene copolymer (HECO1) preferably has a cold xylene soluble fraction (CSF), determined in accordance with ISO 16152 at 25° C., present in an amount of from 8.0 to 25.0 wt. %, more preferably from 10.0 to 22.0 wt. %, even more preferably from 12.0 to 19.0 wt. %, most preferably from 14.0 to 17.0 wt. % relative to the total weight of the first heterophasic propylene-ethylene copolymer (GECO1).

The cold xylene soluble fraction (CSF) of the first heterophasic propylene-ethylene copolymer (HECO1) preferably has an intrinsic viscosity (IV(CSF)) of 2.00 to 4.00 dl/g, more preferably 2.30 to 3.70 dl /g, even more preferably 2.50 to 3.40 dl/g, most preferably 2.70 to 3.30 dl/g.

The cold xylene soluble fraction (CSF) of the first heterophasic propylene-ethylene copolymer (HECO1) preferably has an ethylene content (C2(XX)), measured by infrared spectroscopy in the CRYSTEX assay, from 20.0 to 60.0 wt. %, more preferably from 25.0 to 50.0 wt. %, even more preferably from 30.0 to 45.0 wt. %, most preferably from 35.0 to 40.0 wt. %.

The first heterophasic propylene-ethylene copolymer (HECO1) preferably has a total ethylene content (C2) measured from 3.0 to 15.0 wt. %, more preferably from 4.0 to 12.0 wt. %, even more preferably from 5.0 to 10.0 wt. %, most preferably from 6.0 to 8.0 wt. %.

The first heterophasic propylene-ethylene copolymer (HECO1) preferably has a melt flow index MFR ₂ measured in accordance with ISO 1133-1 at 230°C and a load of 2.16 kg, from 15.0 to 50.0 g/10 min, more preferably 20.0 to 45.0 g/10 min, even more preferably 25.0 to 43.0 g/10 min, most preferably 30.0 to 40.0 g/10 min.

The first heterophasic propylene-ethylene copolymer (HECO1) may be polymerized by methods well known in the art, or alternatively may be commercially available polypropylene. It is understood that commercially available grades are likely to contain conventional additives and nucleating agents that may contribute to the total ash content of the heterophasic polypropylene composition (K).

Second heterophasic propylene-ethylene copolymer (HECO2)

The second heterophasic propylene-ethylene copolymer (HECO2) is different from the first heterophasic propylene-ethylene copolymer (HECO1), which means that at least one of the properties used to define the heterophasic propylene-ethylene copolymers GECO1 and GECO2 must be different.

The second heterophasic propylene-ethylene copolymer (HECO2) according to the present invention is present in an amount of from 5.0 to 20.0 wt. %, more preferably in an amount from 7.0 to 18.0 wt. %, even more preferably in an amount from 9.0 to 16.0 wt. %, most preferably from 10.0 to 14.0 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

The second heterophasic propylene-ethylene copolymer (HECO2) preferably has a melt flow index MFR ₂ measured in accordance with ISO 1133-1 at 230°C and a load of 2.16 kg, from 1.0 g/10 min to 20.0 g/ 10 min, more preferably 2.0 to 17.0 g/10 min, even more preferably 3.0 to 15.0 g/10 min, most preferably 4.0 to 13.0 g/10 min.

The second heterophasic propylene-ethylene copolymer (HECO2) preferably has a total ethylene content (C2) measured from 8.0 to 15.0 wt. %, more preferably from 9.0 to 13.0 wt. %, even more preferably from 9.5 to 12.0 wt. %, most preferably from 10.0 to 11.5 wt. %.

The second heterophasic propylene-ethylene copolymer (HESO2) has a soluble fraction (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 15.0 to 30.0 wt. %, more preferably from 17.0 to 28.0 wt. %, even more preferably from 19.0 to 26.0 wt. %, most preferably from 20.0 to 24.0 wt. % relative to the total weight of the second heterophasic propylene-ethylene copolymer (HECO2).

The soluble (SV) of the second heterophasic propylene-ethylene copolymer (HECO2) preferably has an intrinsic viscosity (IV(SV)) of 2.50 to 5.00 dl/g, more preferably 2.70 to 4.00 dl/g, more more preferably 2.90 to 3.50 dl/g, most preferably 3.10 to 3.40 dl/g.

The soluble fraction (SF) of the second heterophasic propylene-ethylene copolymer (HECO2) preferably has an ethylene content (C2(RF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 20.0 to 60.0 wt. %, more preferably from 25.0 to 50.0 wt. %, even more preferably from 30.0 to 45.0 wt. %, most preferably from 35.0 to 40.0 wt. %.

Accordingly, the second heterophasic propylene-ethylene copolymer (HECO2) has a crystalline fraction (CF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount of from 70.0 to 85.0 wt. %, more preferably from 72.0 to 83.0 wt. %, even more preferably from 74.0 to 81.0 wt. %, most preferably from 76.0 to 80.0 wt. %, relative to the total mass of the second heterophasic propylene-ethylene copolymer (HECO2).

The crystalline fraction (CF) of the second heterophasic propylene-ethylene copolymer (HECO2) preferably has an intrinsic viscosity (IV(IV)) of 1.00 to 2.50 dl/g, more preferably 1.20 to 2.30 dl/g, even more preferably 1.40 to 2.20 dl/g, most preferably 1.50 to 2.10 dl/g.

The crystalline fraction (CF) of the second heterophasic propylene-ethylene copolymer (HECO2) preferably has an ethylene content (C2(CF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 0.5 to 7.0 wt. %, more preferably from 1.5 to 6.0 wt. %, even more preferably from 2.0 to 5.0 wt. %, most preferably from 2.5 to 4.5 wt. %.

The ratio of the intrinsic viscosity of the soluble fraction to the intrinsic viscosity of the crystalline fraction (IV(RF)/IV(RF)) of the second heterophasic propylene-ethylene copolymer (HECO2) is preferably from 1.00 to 3.00, more preferably from 1.20 to 2, 70, even more preferably from 1.40 to 2.40, most preferably from 1.50 to 2.10.

The heterophasic propylene-ethylene copolymer (HECO2) preferably has a cold xylene soluble fraction (CSF), defined in accordance with ISO 16152B, present in an amount of from 15.0 to 30.0 wt. %, more preferably from 17.0 to 28.0 wt. %, even more preferably from 19.0 to 26.0 wt. %, most preferably from 21.0 to 24.0 wt. %, relative to the total mass of the second heterophasic propylene-ethylene copolymer (HECO2).

The cold xylene soluble fraction (CSF) of the second heterophasic propylene-ethylene copolymer (HECO2) preferably has an intrinsic viscosity (IV(CX)) of 2.50 to 5.00 dl/g, more preferably 2.80 to 4.50 dl /g, even more preferably 3.10 to 4.00 dl/g, most preferably 3.40 to 3.80 dl/g.

The cold xylene soluble fraction (CSF) of the second heterophasic propylene-ethylene copolymer (HECO2) preferably has an ethylene content (C2(XX)), measured by infrared spectroscopy in the CRYSTEX assay, from 20.0 to 60.0 wt. %, more preferably from 25.0 to 55.0 wt. %, even more preferably from 30.0 to 50.0 wt. %, most preferably from 33.0 to 48.0 wt. %.

The melt flow ratio of the first and second heterophasic propylene-ethylene copolymers (PTR ₂ (GECO1)/PTR ₂ (GECO2)) is _preferably at least 2.0, more preferably from 2.0 to 20.0, even more preferably from 2.30 to 16.0, even more preferably from 2.60 to 13.0, most preferably from 2.90 to 10, 0.

The second heterophasic propylene-ethylene copolymer (HECO2) can be polymerized by methods well known in the art, or alternatively, it can be a commercially available grade of polypropylene. It is understood that commercially available grades are likely to contain conventional additives and nucleating agents that may contribute to the total ash content of the heterophasic polypropylene composition (K).

Ethylene polymer (PE)

The ethylene polymer (PE) according to the present invention is present in an amount of from 5.0 to 20.0 wt. %, more preferably in an amount from 6.0 to 17.0 wt. %, even more preferably in an amount from 7.0 to 14.0 wt. %, most preferably from 8.0 to 12.0 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

The ethylene polymer (PE) has a density of 895 to 925 kg/m ³ , more preferably 989 to 922 kg/m ³ , even more preferably 900 to 919 kg/m ³ , most preferably 901 to 917 kg/m ³ .

The ethylene polymer (PE) preferably has a melt flow index MFR ₂ measured according to ISO 1133-1 at 190° C. under a load of 2.16 kg, from 0.5 g/10 min to 30.0 g/10 min, more preferably from 0.6 to 25.0 g/10 min, even more preferably 0.8 to 20.0 g/10 min, most preferably 1.0 to 18.0 g/10 min.

In the broadest sense, the ethylene polymer (PE) may be selected from any low-density polyethylene or ethylene-based plastomer that satisfies the above properties.

In one preferred embodiment, the ethylene polymer (PE) is low density polyethylene (LDPE).

In this embodiment, the low density polyethylene (LDPE) preferably has a melt flow index MFR ₂ measured in accordance with ISO 1133-1 at 190°C and a load of 2.16 kg, from 10.0 g/10 min to 30.0 g/ 10 min, more preferably 11.0 to 25.0 g/10 min, even more preferably 12.0 to 20.0 g/10 min, most preferably 13.0 to 18.0 g/10 min.

In this embodiment, the low density polyethylene (LDPE) preferably has a density of 908 to 925 kg/m ³ , more preferably 910 to 922 kg/m ³ , even more preferably 912 to 919 kg/m ³ , most preferably 913 to 917 kg/ ^m3 .

Alternatively, the ethylene polymer (PE) is an ethylene-based plastomer (EP).

In this embodiment, the ethylene-based plastomer (PL) preferably has a melt flow index MFR ₂ measured in accordance with ISO 1133-1 at 190°C and a load of 2.16 kg, from 0.5 g/10 min to 10.0 g /10 min, more preferably 0.6 to 7.0 g/10 min, even more preferably 0.8 to 5.0 g/10 min, most preferably 1.0 to 3.0 g/10 min.

In this embodiment, the ethylene-based plastomer (PL) preferably has a density of from 895 to 908 kg/m ³ , more preferably from 989 to 906 kg/m 3 , even more preferably from 900 to 905 kg/m ³ , most preferably from 901 to 904 kg/ ^m3 .

In said embodiment, the ethylene-based plastomer (EP) preferably contains comonomer(s) selected from C3 to C10 alpha-olefins, more preferably from C4 to C8 alpha-olefins, even more preferably from 1-hexene or 1-octene, most preferably 1-octene.

Particularly preferably, the ethylene-based plastomer (EP) contains 1-octene as the sole comonomer.

In this embodiment, the ethylene-based plastomer preferably has a comonomer content, measured by quantitative ¹³ C-NMR analysis, from 3.0 to 6.0 mol. %, more preferably from 4.0 to 5.5 mol. %, even more preferably from 4.3 to 5.3 mol. %, most preferably from 4.5 to 5.0 mol. %.

The ethylene polymer (PE) can be polymerized by methods well known in the art or, alternatively, it can be a commercially available grade of polyethylene. It is understood that commercially available grades are likely to contain conventional additives and nucleating agents that may contribute to the total ash content of the heterophasic polypropylene composition (K).

Heterophasic polypropylene composition (K)

The heterophasic polypropylene composition (K) according to the present invention contains from 60.0 to 85.0 wt. % of the first heterophasic propylene-ethylene copolymer (HECO1), from 5.0 to 20.0 wt. % of the second heterophasic propylene-ethylene copolymer (HECO2) and from 5.0 to 20.0 wt. % ethylene polymer (PE).

In a preferred embodiment, the heterophasic polypropylene composition (K) contains from 65.0 to 82.0 wt. % of the first heterophasic propylene-ethylene copolymer (HECO1), from 7.0 to 18.0 wt. % of the second heterophasic propylene-ethylene copolymer (HECO2) and from 6.0 to 17.0 wt. % ethylene polymer (PE).

In another preferred embodiment, the heterophasic polypropylene composition (K) contains from 70.0 to 80.0 wt. % of the first heterophasic propylene-ethylene copolymer (HECO1), from 9.0 to 16.0 wt. % of the second heterophasic propylene-ethylene copolymer (HECO2) and from 7.0 to 14.0 wt. % ethylene polymer (PE).

In another preferred embodiment, the heterophasic polypropylene composition (K) contains from 74.0 to 78.0 wt. % of the first heterophasic propylene-ethylene copolymer (HECO1), from 10.0 to 14.0 wt. % of the second heterophasic propylene-ethylene copolymer (HECO2) and from 8.0 to 12.0 wt. % ethylene polymer (PE).

In each embodiment, the combined amount of the first heterophasic propylene-ethylene copolymer (HECO1), the second heterophasic propylene-ethylene copolymer (HECO2) and the ethylene polymer (PE) is greater than or equal to 95 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

The heterophasic polypropylene composition (K) has a melt flow index MFR ₂ measured in accordance with ISO 1133-1 at 230°C and a load of 2.16 kg, from 15.0 to 40.0 g/10 min, more preferably from 16. 0 to 35.0 g/10 min, even more preferably 17.0 to 30.0 g/10 min, most preferably 18.0 to 25.0 g/10 min.

The heterophasic polypropylene composition (K) has a crystalline fraction (CF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 77.0 to 95.0 wt. %, more preferably from 80.0 to 90.0 wt. %, even more preferably from 82.0 to 88.0 wt. %, most preferably from 83.0 to 86.0 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

The crystalline fraction (CF) of the heterophasic polypropylene composition (C) preferably has an intrinsic viscosity (IV(IV)) of 1.00 to 2.00 dl/g, more preferably 1.20 to 2.00 dl/g, even more preferably 1.30 to 1.80 dl/g, most preferably 1.40 to 1.60 dl/g.

The crystalline fraction (CF) of the heterophasic polypropylene composition (C) preferably has an ethylene content (C2(CF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 5.0 to 20.0 wt. %, more preferably from 7.0 to 17.0 wt. %, even more preferably from 9.0 to 15.0 wt. %, most preferably from 10.0 to 13.0 wt. %.

The heterophasic polypropylene composition (K) has a soluble fraction (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 5.0 to 23.0 wt. %, more preferably from 10.0 to 20.0 wt. %, even more preferably from 13.0 to 18.0 wt. %, most preferably from 15.0 to 17.0 wt. %, relative to the total mass of the heterophasic polypropylene composition (K).

The soluble fraction (SF) of the heterophasic polypropylene composition (K) preferably has an intrinsic viscosity (IV(RF)) of 2.00 to 3.50 dl/g, more preferably 2.30 to 3.20 dl/g, even more preferably 2.50 to 3.00 dl/g, most preferably 2.60 to 2.80 dl/g.

The soluble fraction (SF) of the heterophasic polypropylene composition (K) preferably has an ethylene content (C2(RF)), measured by infrared spectroscopy in the CRYSTEX assay, from 25.0 to 50.0 wt. %, more preferably from 30.0 to 45.0 wt. %, even more preferably from 33.0 to 40.0 wt. %, most preferably from 35.0 to 37.0 wt. %.

The ratio of the intrinsic viscosity of the soluble fraction to the intrinsic viscosity of the crystalline fraction (CV(RF)/CV(CP)) of the heterophasic polypropylene composition (K) is preferably from 1.40 to 3.00, more preferably from 1.40 to 3.00, more preferably from 1.50 to 2.50, even more preferably from 1.60 to 2.20, most preferably from 1.70 to 2.00.

The heterophasic polypropylene composition (K) preferably has a total ethylene content (C2) measured from 10.0 to 20.0 wt. %, more preferably from 12.0 to 18.0 wt. %, even more preferably from 13.0 to 17.0 wt. %, most preferably from 14.0 to 16.0 wt. %.

It has been found that although the inclusion of fillers is known to improve the mechanical properties of polypropylene compositions, they have a significant negative effect on the optical properties of the resulting compositions and should therefore be avoided or at least kept to a minimum in the context of the present invention.

The heterophasic polypropylene composition (K) of the present invention preferably has a low content of mineral fillers. This mineral filler content can be estimated by measuring the ash content of the heterophasic polypropylene composition (K). The heterophasic polypropylene composition (K) thus preferably has an ash content of less than 2.0 wt. %, more preferably less than 1.9 wt. %, even more preferably less than 1.8 wt. %, most preferably less than 1.7 wt. % relative to the total weight of the heterophasic polypropylene composition (K).

The heterophasic polypropylene composition (K) according to the present invention has a favorable balance of stiffness and impact properties, despite the low mineral filler content and the relatively low amount of amorphous phase. In addition, the heterophasic polypropylene composition (K) has a good overall light transmittance.

As such, the heterophasic polypropylene composition (K) of the present invention is characterized by its mechanical properties and transmittance.

The heterophasic polypropylene composition (K) preferably has an overall light transmittance, measured in accordance with ASTM D1003 on 60 x 60 x 3 mm injection molded plates, of 40 to 100%, more preferably 42 to 80%, even more preferably 44 up to 60%, most preferably from 46 to 50%.

The heterophasic polypropylene composition (K) preferably has a tensile modulus measured according to ISO 527-1.-2 on a type 1B tensile specimen; 170 x 10 x 4 mm (ISO 1B), 1200 to 2000 MPa, more preferably 1300 to 1900 MPa, even more preferably 1400 to 1800 MPa, most preferably 1500 to 1700 MPa.

The heterophasic polypropylene composition (K) preferably has a Charpy notched impact strength at 23°C measured in accordance with ISO 179 1eA using injection molded rod test pieces measuring 80 x 10 x 4 mm prepared in accordance with EN ISO 19069- 2, from 5.0 to 30.0 kJ/ ^m2 , more preferably from 7.0 to 25.0 kJ/ ^m2 , even more preferably from 8.0 to 20.0 kJ/ ^m2 , most preferably from 9 .0 to 15.0 kJ/m ² .

The heterophasic polypropylene composition (C) preferably has a notched Charpy impact strength at -20°C measured in accordance with ISO 179 1eA using injection molded rod test pieces measuring 80 x 10 x 4 mm prepared in accordance with EN ISO 19069 -2, from 3.5 to 20.0 kJ/ ^m2 , more preferably from 4.0 to 15.0 kJ/ ^m2 , even more preferably from 4.5 to 12.0 kJ/ ^m2 , most preferably from 5.0 to 10.0 kJ/ ^m2 .

The heterophasic polypropylene composition (K) preferably has a puncture energy at 23°C measured in accordance with ISO 6603-2 using injection molded plates measuring 60x60x3 mm and a test speed of 4.4 m/s, from 30.0 up to 60.0 J, more preferably from 32.0 to 55.0 J, even more preferably from 34.0 to 50.0 J, most preferably from 36.0 to 45.0 J.

The heterophasic polypropylene composition (K) preferably has a puncture energy at -20°C measured in accordance with ISO 6603-2 using injection molded plates measuring 60x60x3 mm and a test speed of 4.4 m/s, from 20. 0 to 100.0 J, more preferably 30.0 to 90.0 J, even more preferably 40.0 to 80.0 J, most preferably 50.0 to 70.0 J.

The heterophasic polypropylene composition (K) preferably has an energy at maximum force at 23°C, measured in accordance with ISO 6603-2 using injection molded plates measuring 60x60x3 mm and a test speed of 4.4 m/s, from 15 .0 to 40.0 J, more preferably 18.0 to 35.0 J, even more preferably 20.0 to 30.0 J, most preferably 21.0 to 25.0 J.

The heterophasic polypropylene composition (K) preferably has an energy at maximum force at -20°C, measured in accordance with ISO 6603-2 using injection molded plates measuring 60x60x3 mm and a test speed of 4.4 m/s, from 20.0 to 60.0 J, more preferably 25.0 to 50.0 J, even more preferably 30.0 to 45.0 J, most preferably 35.0 to 40.0 J.

It is particularly preferable that the balance of properties be maximized. Thus, preferably the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (I):

in this case, the impact strength with a Charpy notch is measured at 23°C and expressed in kJ/m ² ,

puncture energy is measured at 23°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

More preferably, the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (Ia):

in this case, the impact strength with a Charpy notch is measured at 23°C and expressed in kJ/m ² ,

puncture energy is measured at 23°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

Even more preferably, the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (Ib):

in this case, the impact strength with a Charpy notch is measured at 23°C and expressed in kJ/m ² ,

puncture energy is measured at 23°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

Most preferably, the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy the inequality (Ic):

in this case, the impact strength with a Charpy notch is measured at 23°C and expressed in kJ/m ² ,

puncture energy is measured at 23°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

It is also preferable that the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (II):

in this case, the impact strength with a Charpy notch is measured at -20°C and expressed in kJ/m ² ,

puncture energy is measured at -20°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

More preferably, the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (IIa):

in this case, the impact strength with a Charpy notch is measured at -20°C and expressed in kJ/m ² ,

puncture energy is measured at -20°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

Even more preferably, the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (IIb):

in this case, the impact strength with a Charpy notch is measured at -20°C and expressed in kJ/m ² ,

puncture energy is measured at -20°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

Most preferably, the numerical values of Charpy notched impact strength (CIT), puncture energy, soluble fraction content (SF) and total light transmittance satisfy inequality (IIc):

in this case, the impact strength with a Charpy notch is measured at -20°C and expressed in kJ/m ² ,

puncture energy is measured at -20°C and expressed in J,

the content of the soluble fraction (SF) is indicated in mass. %, A

The total light transmittance is indicated in %.

Product

In another aspect, the present invention is directed to providing an article that contains a heterophasic polypropylene composition (K).

In particular, the product of the present invention is an injection molded product, preferably an automobile product.

Examples

1. Definitions/methods of determination

Melt flow indicators

The melt flow index (MFI) is determined in accordance with ISO 1133-1 and is indicated in g/10 min. MFR is an indicator of the fluidity and, therefore, the manufacturability of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. MFI ₂ of polypropylene is determined at a temperature of 230°C and a load of 2.16 kg. MFI ₂ of polyethylene is determined at a temperature of 190°C and a load of 2.16 kg.

Differential scanning calorimetry (DSC)

Differential scanning calorimetry (DSC), melting point ( _Tm ) and enthalpy of fusion ( _Hm ), crystallization temperature ( _Tk ) and heat of crystallization ( _Hk , _Hcr ) are measured using a TA Instrument Q200 device for differential scanning calorimetry (DSC) ) on samples weighing from 5 to 7 mg. DSC is carried out in accordance with ISO 11357/part 3/method C2 in a heating/cooling/heating cycle with a scan rate of 10°C/min over a temperature range of -30 to +225°C. The crystallization temperature ( _Tc ) and heat of crystallization ( _Hc ) are determined in the cooling stage, while the melting temperature ( _Tmelt ) and enthalpy of fusion ( _Hpl ) are determined in the second heating stage.

Quantitative determination of polyethylene microstructure using ¹³ C NMR spectroscopy

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

Quantitative ^13C { ^1H } NMR spectra recorded in the molten state using a Bruker Avance III 500 NMR spectrometer operating at frequencies of 500.13 and 125.76 MHz for ^1H and ^13C , respectively. All spectra were recorded using a ^13C optimized 7mm magic angle spinning (MAS) probe head at 150°C using nitrogen gas for all pneumatic equipment. Approximately 200 mg of material was placed in a zirconia MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This setup was chosen primarily because of the high sensitivity required for rapid identification and accurate quantification. (Klimke, K., Parkinson, M., Piel, S., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.; Parkinson, M., Klimke, K., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2007;208:2128.; Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373; NMR Spectroscopy of Polymers: Innovative Strategies for Complex Macromolecules, Chapter 24, 401 (2011)). Standard single-pulse excitation was employed utilising the transient NOE at short recycle delays of 3s (Pollard, M., Klimke, K., Graf, R., Spiess, HW, Wilhelm, M., Sperber, O., Piel, C. , Kaminsky, W., Macromolecules 2004;37:813.; Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2006 ; 207:382.) and the RS-HEPT decoupling scheme (Filip, X., Tripon, C., Filip, C, J. Mag. Resn. 2005, 176, 239.; Griffin, JM, Tripon, C, Samoson , A., Filip, C, and Brown, SP, Mag. Res. in Chem. 2007 45, S1, S198). A total of 1024 (1k) transition states per spectrum were obtained. This setup was chosen due to its high sensitivity to low comonomer content.

Quantitative ^13C { ^1H } NMR spectra were processed, integrated, and quantified using special spectral analysis automation programs. All chemical shifts are internally related to the overall methylene signal (δ+) at 30.00 ppm. (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.).

A typical procedure for ethylene-octene copolymers is given below.

Ethylene-octene copolymer - octene content

Characteristic signals consistent with 1-octene incorporation were observed (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.; Liu, W., Rinaldi, P., Mcintosh, L., Quirk , P., Macromolecules 2001, 34, 4757; Qiu, X., Redwine, D., Gobbi, G., Nuamthanom, A., Rinaldi, P., Macromolecules 2007, 40, 6879) and all comonomer content was calculated relative to to all other monomers present in the polymer.

Characteristic signals resulting from isolated inclusion of 1-octene were observed, i.e. EEOEE comonomer sequences. Isolated 1-octene inclusion was quantified using the integral of the signal at 38.37 ppm. This integral is attributed to unresolved signals corresponding to the *B6 and *βB6B6 centers of isolated (EEOEE) and isolated double non-consecutive (EEOOEE) 1-octene sequences, respectively. To compensate for the influence of two *βВ6В6 centers, use the integral of the ββВ6В6 center at 24.7 ppm:

О=I _*B6+**pB6B6 - 2 * I _ββB6B6

When characteristic signals resulting from sequential 1-octene incorporation (EEOOEE) were observed, such non-consecutive 1-octene incorporation was quantified using the integral of the signal at 40.57 ppm attributed to the ααB6B6 centers, taking into account the number of reporting centers per comonomer:

OO=2 * I _ααB6B6

Characteristic signals resulting from non-sequential incorporation of 1-octene were also observed, i.e. comonomer sequences EEOOEE. This non-sequential incorporation of 1-octene was quantified using the integral of the signal at 24.7 ppm attributed to the βB6B6 center, taking into account the number of reporting centers per comonomer:

OEO=2 * I _ββB6B6

In the absence of other signals indicating other comonomer sequences observed, total 1-octene comonomer content was calculated solely based on the number of isolated (EEOEE), double-followed (EEOOEE), and non-followed (EEOOEE) 1-octene comonomer sequences :

O _total =O+OO+OEO

Characteristic signals resulting from saturation of the end groups were observed. These saturated end groups were quantified using the average integral of the two resolved signals at 22.84 and 32.23 ppm. Integral 22.84 ppm are attributed to unresolved signals corresponding to the 2B6 and 2S centers of 1-octene and the saturated end of the chain, respectively. Integral 32.23 ppm are attributed to unresolved signals corresponding to the 3B6 and 3S centers of 1-octene and the saturated end of the chain, respectively. To compensate for the influence of 1-octene centers 2B6 and 3B6, the total content of 1-octene is used:

S=(1/2)*(I _2S+2B6 +I _3S+3B6 -2*O _total )

Ethylene comonomer content was quantified using the integral of the (volume) signals of bulk methylene at 30.00 ppm. This integral included the γ and 4B6 centers from 1-octene, as well as the δ+ centers. The total ethylene comonomer content was calculated based on the volume integral and taking into account the observed 1-octene sequences and end groups:

E _total =(1/2)*[I _about +2*O+1*OO+3*OEO+3*S]

Then the total mole fraction of 1-octene in the polymer was calculated:

fO=(O _total /(E _total +O _total )

The total incorporation of 1-octene comonomer in mole percent was calculated from the mole fraction in the standard manner:

O[mol. %]=100 * fО

The molar percentage of ethylene inclusion was calculated using the formula:

E[moln. %]=100 - O[mol. %].

Dynamic mechanical thermal analysis (DMTA)

The glass transition temperature Tg is determined using dynamic mechanical thermal analysis (DMTA) in accordance with ISO 6721-7. Measurements are carried out in torsion mode on pressed samples (40×10×1 mm) at temperatures from -130°C to +150°C with a heating rate of 2°C/min and a frequency of 1 Hz. The elastic modulus G' is determined at +23°C in accordance with ISO 6721-7:1996. Measurements are carried out in torsion mode on pressed samples (40×10×1 mm) at temperatures from -130°C to +150°C with a heating rate of 2°C/min and a frequency of 1 Hz.

Cold xylene soluble fraction (CSF)

The fraction soluble in cold xylene at room temperature (RCS, wt.%) was determined at 25°C according to ISO 16152; ^5th edition; 2005-07-01.

Elastic modulus

The tensile modulus, tensile strength and tensile strength were determined in accordance with ISO 527-2 (traverse speed = 1 mm/min; test speed 50 mm/min at 23°C) on sample 1B.

Impact strength with notch (IPS)

Charpy notched impact strength (CIT) was measured in accordance with ISO 179 1eA at +23°C or -20°C using 80 x 10 x 4 mm injection molded rod test specimens prepared in accordance with EN ISO 19069 -2.

Crystex Analysis

Method for determination of crystalline and soluble fractions The crystalline fraction (CF) and soluble fraction (SF) of polypropylene (PP) compositions, as well as the comonomer content and intrinsic viscosity of the corresponding fractions were analyzed using CRYSTEX QC, Polymer Char (Valencia, Spain).

A schematic representation of the CRYSTEX QC instrument is shown in FIG. 1a. The crystalline and amorphous fractions are separated by temperature cycling of dissolution in 1,2,4-trichlorobenzene (1,2,4-TCB) at 160°C, crystallization at 40°C and re-dissolution in 1,2,4-TCB at 160°C C, as shown in FIG. 1b. Quantitative determination of RF and CP and determination of ethylene content (C2) is achieved using an infrared detector (IR4), and an integrated 2-capillary viscometer is used to determine the intrinsic viscosity (IV).

The IR4 detector is a multi-wavelength detector that measures IR absorption in two different ranges (CH ₃ stretching (centered at approximately 2960 cm ^-1 ) and CH _X stretching (2700-3000 cm ^-1 )) that can be used to determine the concentration and content of ethylene in ethylene-propylene copolymers. The IR4 detector is calibrated with a series of 8 EP copolymers with a known ethylene content from 2 to 69 wt. % (determined by ¹³ C-NMR) and at various concentrations from 2 to 13 mg/ml each. To simultaneously account for both characteristics, concentration and ethylene content, for the various polymer concentrations expected in the Crystex assays, the following calibration equations were used:

The constants a - e for equation 1 and a - f for equation 2 were determined using least squares regression analysis.

CH3/1000C is converted to ethylene content in mass. % using the following ratio:

The amount of soluble fraction (SF) and crystalline fraction (CF) are correlated by calibrating the RC with the amount of “cold xylene soluble” (CXS) and, accordingly, the cold xylene insoluble fraction (CXF), determined in accordance with the standard gravimetric method in accordance with ISO16152. Calibration of DO is achieved by testing different E-P copolymers with DO content in the range of 2-31 wt. %. The defined RK calibration is linear:

The intrinsic viscosity (IV) of the original EP copolymer and its soluble and crystalline fractions is determined using a built-in 2-capillary viscometer and correlated with the corresponding IV values determined by the standard method in decalin in accordance with ISO 1628-3. Calibration is achieved using various EP PP copolymers with IV = 2-4 dl/g. The defined calibration curve is linear:

A sample of the analyzed PP composition is weighed in concentrations from 10 mg/ml to 20 mg/ml. After automatically filling a vial with 1,2,4-TCB containing 250 mg/L 2,6-tert-butyl-4-methylphenol (BNT) as an antioxidant, the sample is dissolved at 160°C until completely dissolved, usually within 60 min with constant stirring at a speed of 400 rpm. To avoid degradation of the sample, the polymer solution is enveloped in an N ₂ atmosphere during dissolution.

As shown in FIG. 1a and b, a certain volume of the sample solution is introduced into a column filled with an inert carrier, where the sample crystallizes and the soluble fraction is separated from the crystalline part. This process is repeated twice. During the first injection, the entire sample is measured at high temperature, determining IV [dl/g] and C2 [wt. %] PP composition. During the second injection, the soluble fraction (at low temperature) and the crystalline fraction (at high temperature) are measured with the crystallization cycle (wt.% RF, wt.% C2, IV).

Determination of C2 content for calibration standards based on ¹³ C NMR spectroscopy

Quantitative ^13C { ^1H } NMR spectra were recorded in the dissolved state on a Bruker Avance III 400 NMR spectrometer operating at frequencies of 400.15 and 100.62 MHz for ^1H and ^13C , respectively. All spectra were recorded using a ^13C optimized 10mm extended temperature sensor head at 125°C using nitrogen gas for all pneumatic equipment. Approximately 200 mg of the material was dissolved in 3 ml of 1,2-tetrachloroethane-d ₂ (TCE-d ₂ ) along with chromium (III) acetylacetonate (Cr(acac) ₃ ), resulting in a 65 mM solution of the relaxant in the solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure solution homogeneity, after initial sample preparation in the heating block, the NMR tube was additionally heated in a rotary oven for at least 1 hour. After insertion into the magnet, the tube rotated at a frequency of 10 Hz. This setup was chosen primarily due to the high resolution and quantitative requirements for accurate ethylene quantification. Standard single-pulse excitation was used without NOE, using an optimized tip angle, a 1-second recycle delay, and a WALTZ16 two-level decoupling circuit (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha , A., Baugh, D. Winniford, V., J. Mag. Reson. 187 (2007) 225, Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128). A total of 6144 (6k) transition states were obtained per spectrum. Quantitative ¹³ C{ ¹ H} NMR spectra were processed, integrated, and the corresponding quantitative properties were determined from the integrals. All chemical shifts were indirectly assigned to the central methylene group of the ethylene block (EEE) at 30.00 ppm. using solvent chemical shift. This approach allowed for comparable references even in the absence of this structural unit. Characteristic signals corresponding to the incorporation of ethylene were observed (Cheng, HN, Macromolecules 17 (1984), 1950), and the comonomer fraction was calculated as the fraction of ethylene in the polymer relative to all monomers in the polymer: fE = (E/(P+E). Fraction comonomer was quantified using the method of Wang et al. (Wang, W. J., Zhu, S., Macromolecules 33 (2000), 1157) by integrating multiple signals over the entire spectral region in the ¹³ C{ ¹ H} spectra. This method was chosen for its robustness and ability to account for the presence of regio-defects when needed. The integral regions have been slightly adjusted to increase applicability across the range of comonomer contents encountered. For systems with very low ethylene contents, where only isolated ethylene was observed in PPEPP sequences, Wang et al.'s method was modified by reducing the influence of integration of sites that are no longer present.This approach reduced the overestimation of ethylene content for such systems and was achieved by reducing the number of sites used to determine the absolute ethylene content to E=0.5( Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ)). By using this set of centers, the corresponding integral equation becomes E=0.5 (IH+IG+0.5 (IC+ID)), using the same notation as in the paper by Wang et. al. (Wang, W. J., Zhu, S., Macromolecules 33 (2000), 1157). The equations used for absolute propylene content were not changed. The molar percentage of comonomer inclusion was calculated from the mole fraction: E [mol. %]=100 * fE. The mass percentage of comonomer inclusion was calculated from the mole fraction: E [wt. %]=100 * (fE * 28.06) / ((fE * 28.06)+((1-fE) * 42.08))

Ash content

The ash content of the polymer was determined by burning the polymer in a suspended platinum crucible. Approximately 100 grams of polymer are weighed into the crucible. The crucible is then heated in the flame of a Bunsen burner so that the polymer burns slowly. After the polymer has completely burned out, the crucible is cooled, dried and weighed. The ash content is then the mass of the residue divided by the mass of the polymer sample. At least two measurements are taken and, if the difference between measurements is greater than 7 ppm, a third measurement is taken.

Puncture energy and energy at maximum force

Puncture energy and energy at maximum force were determined on 60×60×3 mm ³ plates made from injection molded plates using an instrumental drop weight test in accordance with ISO 6603-2. The test was carried out at either 23°C or -20°C (as specified) with a lubricated tip of 20 mm diameter and an impact speed of 4.4 mm/s. Six specimens were tested for each specimen and the resulting six force-deflection curves were used to calculate the average energy at maximum force and puncture energy. In addition, the type of impact failure was assessed. ISO6603-2 defines the following types of impact failure, the number in brackets is assigned to calculate the numerical value of impact failure (average value obtained from six tested specimens):

PG plastic deformation (zero tilt at maximum force) followed by deep stretching (1)

PS plastic deformation (zero tilt at maximum force) followed by (at least partial) stable cracking (2)

PN plastic deformation (zero tilt at maximum force) followed by unstable cracking (3)

NP no plastic deformation (4)

Total light transmittance and turbidity

The optical properties of polypropylene (total transmittance and haze) were determined on 60×60×3 mm ³ plates made from injection molded plates and measured according to ASTM D1003.

Intrinsic viscosity

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

2. Experimental part

a) Polymerization of heterophasic propylene-ethylene copolymers

The heterophasic propylene-ethylene copolymers used in the present invention were polymerized using methods well known in the art using the polymerization conditions shown in Table 1.

The catalyst used for PP1 and PP2 was an emulsion-type Ziegler-Natta catalyst identical to the catalyst used in the polymerization of the examples according to the invention WO 2017/148970 A1.

The catalyst for PP3 was Avant ZN180M, provided by LyondellBasell.

For each of PP1, PP2 and PP3, the cocatalyst was TEAL and the external donor was dicyclopentyldimethoxysilane (donor D).

After polymerization under the conditions specified in Table 1, the polymers obtained in the reactor were supplemented with standard additives for polypropylene, as indicated in the lower part of Table 1, resulting in the final PP1, PP2 and PP3 with additives whose properties are shown in the table. 2.

b) Mixed compositions

The compositions according to the invention and comparative compositions were prepared according to the recipes given in table 3. Additives were added in the form of 2.0 wt. % dry mixture of additives. The Inventive Examples and Comparative Examples were prepared by melt mixing the components in a Coperion ZSK18 parallel rotating twin screw extruder. The temperature profile from the hopper to the head was 20-190-200-220-220-190-170-200°C and the screw rotation speed was 400 rpm. The polymer melt mixture was discharged and granulated.

PP4 is an industrially produced automotive grade EE001AI polypropylene sold by Borealis AG.

LDPE is a commercially available low density polyethylene, CA9150, having a melt flow index MFR ₂ of 15.0 g/10 min and a density of 915 kg/m ³ sold by Borealis AG.

PL is an industrially produced ethylene-octene plastomer Queo 0201 with a melt flow index PTR ₂ of 1.1 g/10 min, a density of 902 kg/m ³ and a 1-octene content of 4.8 mol. % sold by Borealis AG.

The properties of the final compositions are given in Table 4.

As can be seen from Table 4, the compositions of the invention have an excellent balance of stiffness, impact strength and optical properties. The compositions of the invention have surprisingly good impact properties, given the relatively low RF content, which allows for high stiffness to be achieved. In addition (although not described in Table 4), all examples according to the invention showed only the SG deflection characteristic at 23°C, i.e. deep pulling after zero tilt at maximum force, which is useful for automotive applications. As can be seen from the comparison of examples of the invention with CE1, the addition of GECO2 (i.e. PP2 or PP3) and ethylene polymer (i.e. LDPE or PL) leads to improved mechanical properties, in particular impact properties. Comparison of IE1 and CE1 shows detrimental the influence of mineral fillers on the optical properties of the compositions, showing that the use of these fillers, which are often used to improve mechanical properties, should be avoided. Finally, the compositions of the invention have superior optical properties compared to similar compositions previously used for similar automotive applications (ie CE3).

Claims (66)

1. Heterophase polypropylene composition (K) for use in automotive products, including: a) from 60.0 to 85.0 wt. % of the first heterophasic propylene-ethylene copolymer (GECO1), having: i) crystalline fraction (CF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount from 75.0 to 92.0 wt. % relative to the total mass of GESO1; ii) soluble fraction (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount of from 8.0 to 25.0 wt. % relative to the total mass of GESO1; iii) intrinsic viscosity of the soluble fraction (IV(RF)) from 2.00 to 4.00 dl/g; b) from 5.0 to 20.0 wt. % of the second heterophasic propylene-ethylene copolymer (HECO2), different from the first heterophasic propylene-ethylene copolymer (HECO1) and having i) soluble fraction (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in an amount of from 15.0 to 30.0 wt. % relative to the total mass of GESO2; ii) intrinsic viscosity of the soluble fraction (IV(RF)) from 2.5 to 5.0 dl/g, and c) from 5.0 to 20.0 wt. % ethylene polymer (PE), selected from an ethylene- and LDPE-based plastomer having a density of 895 to 925 kg/m ³ ; wherein the heterophasic polypropylene composition (K) has a melt flow index PTR ₂ , measured in accordance with ISO 1133-1 at 230°C and a load of 2.16 kg, from 15.0 to 40.0 g/10 min, and a soluble fraction (RF), determined in accordance with the CRYSTEX QC ISO 6427-B method, present in quantities from 5.0 to 23.0 wt. % relative to the total weight of the heterophasic polypropylene composition (K), and the combined amount of the first heterophasic propylene-ethylene copolymer (HECO1), the second heterophasic propylene-ethylene copolymer (HECO2) and the ethylene polymer (PE) is greater than or equal to 95 wt. % relative to the total weight of the heterophasic polypropylene composition (K). 2. Heterophase polypropylene composition (K) according to claim 1, having an ash content equal to or less than 2 wt. %. 3. Heterophasic polypropylene composition (K) according to claim 1 or 2, having one or more, preferably all of the following properties: i) characteristic viscosity of the soluble fraction (IV(RF)) from 2.00 to 3.50 dl/g; ii) ethylene content in the soluble fraction (C2(RF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 25.0 to 50.0 wt. %; iii) intrinsic viscosity of the crystalline fraction (IV(IV)) from 1.00 to 2.00 dl/g; iv) ethylene content in the crystalline fraction (C2(CP)), measured by infrared spectroscopy in the CRYSTEX analysis, from 5.0 to 20.0 wt. %; v) the ratio between the intrinsic viscosity of the soluble fraction and the intrinsic viscosity of the crystalline fraction (IV(RF)/IV(CP)) from 1.40 to 3.00, and vi) total ethylene content (C2), measured by infrared spectroscopy in the CRYSTEX analysis, from 10.0 to 20.0 wt. %. 4. Heterophasic polypropylene composition (K) according to claim 1 or 2, in which the first heterophasic propylene-ethylene copolymer (HECO1) has one or more, preferably all of the following properties: i) ethylene content in the soluble fraction (C2(RF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 20.0 to 60.0 wt. %; ii) intrinsic viscosity of the crystalline fraction (IV(IV)) from 1.00 to 2.00 dl/g; iii) ethylene content in the crystalline fraction (C2(CP)), measured by infrared spectroscopy in the CRYSTEX analysis, from 0.5 to 5.0 wt. %, And iv) the ratio between the intrinsic viscosity of the soluble fraction and the intrinsic viscosity of the crystalline fraction (IV(RF)/IV(CP)) from 1.00 to 3.00. 5. Heterophasic polypropylene composition (K) according to claim 1 or 2, in which the first heterophasic propylene-ethylene copolymer (HECO1) has one or more, preferably all of the following properties: i) melt flow index PTR ₂ measured according to ISO 1133-1 at 230°C and a load of 2.16 kg, from 15.0 to 50.0 g/10 min, and ii) total ethylene content (C2), measured by infrared spectroscopy in the CRYSTEX analysis, from 3.0 to 15.0 wt. %. 6. Heterophasic polypropylene composition (K) according to claim 1 or 2, in which the second heterophasic propylene-ethylene copolymer (HECO2) has one or more, preferably all of the following properties: i) melt flow index PTR2, measured according to ISO 1133-1 at 230°C and a load of 2.16 kg, from 1.0 to 20.0 g/10 min; ii) total ethylene content (C2), measured by infrared spectroscopy in the CRYSTEX analysis, from 8.0 to 15.0 wt. %; iii) ethylene content in the soluble fraction (C2(RF)), measured by infrared spectroscopy in the CRYSTEX analysis, from 20.0 to 60.0 wt. %; iv) intrinsic viscosity of the crystalline fraction (IV(IV)) from 1.00 to 2.50 dl/g; v) ethylene content in the crystalline fraction (C2(CP)), measured by infrared spectroscopy in the CRYSTEX analysis, from 0.5 to 7.0 wt. %, And vi) the ratio between the intrinsic viscosity of the soluble fraction and the intrinsic viscosity of the crystalline fraction (IV(RF)/IV(CP)) from 1.00 to 2.50. 7. Heterophasic polypropylene composition (K) according to claim 1 or 2, in which the melt flow ratio PTR ₂ , measured in accordance with ISO 1133-1 at 230 ° C and a load of 2.16 kg, of the first heterophasic propylene-ethylene copolymer ( GECO1) and the second heterophasic propylene-ethylene copolymer (HECO2), MTR ₂ (HECO1)/MTR ₂ (HECO2) is at least 2.0. 8. Heterophase polypropylene composition (K) according to claim 1 or 2, in which the ethylene polymer (PE) has a melt flow index PTR ₂ , measured according to ISO 1133-1 at 190 ° C and a load of 2.16 kg, from 0.5 up to 30.0 g/10 min. 9. The heterophasic polypropylene composition (K) according to claim 1 or 2, wherein the ethylene polymer (PE) is an ethylene-based plastomer (PL), wherein the ethylene-based plastomer has one or more, preferably all of the following properties: i) melt flow index PTR ₂ measured according to ISO 1133-1 at 190°C and a load of 2.16 kg, from 0.5 to 10.0 g/10 min; ii) density from 895 to 908 kg/m ³ ; iii) a comonomer or comonomers selected from C3-C10 alpha-olefins, and iv) comonomer content, measured by quantitative ¹³ C-NMR analysis, from 3.0 to 6.0 mol%. 10. The heterophasic polypropylene composition (K) according to claim 1 or 2, wherein the ethylene polymer (PE) is low-density polyethylene, wherein the low-density polyethylene has any of, preferably both of the following properties: i) melt flow index PTR ₂ measured according to ISO 1133-1 at 190°C and a load of 2.16 kg, from 10.0 to 30.0 g/10 min, and ii) density from 908 to 925 kg/m ³ . 11. Heterophasic polypropylene composition (K) according to claim 1 or 2, having an overall light transmittance, measured in accordance with ASTM D1003 on injection molded plates measuring 60x60x3 mm, from 40 to 100%. 12. Heterophasic polypropylene composition (K) according to claim 1 or 2, having one or more, preferably all of the following properties: i) tensile modulus measured according to ISO 527-1.-2 on a Type 1B tensile specimen; 170×10×4 mm (ISO 1B), from 1200 to 2000 MPa; ii) Charpy notched impact strength at 23°C, measured in accordance with ISO 179 1eA using 80 x 10 x 4 mm injection molded rod test specimens prepared in accordance with EN ISO 19069-2, from 5.0 up to 30.0 kJ/ ^m2 ; iii) Charpy notched impact strength at -20°C, measured in accordance with ISO 179 1eA using injection-molded rod test pieces measuring 80 x 10 x 4 mm prepared in accordance with EN ISO 19069-2, from 3, 5 to 20.0 kJ/ ^m2 ; iv) puncture energy at 23°C measured in accordance with ISO 6603-2 using injection molded plates measuring 60 x 60 x 3 mm and a test speed of 4.4 m/s, from 30.0 to 60.0 J; v) puncture energy at -20°C measured in accordance with ISO 6603-2 using injection molded plates measuring 60 x 60 x 3 mm and test speed 4.4 m/s, from 20.0 to 100.0 J ; vi) energy at maximum force at 23°C, measured in accordance with ISO 6603-2 using injection molded plates measuring 60 x 60 x 3 mm and a test speed of 4.4 m/s, from 15.0 to 40.0 J, and vii) energy at maximum force at -20°C, measured in accordance with ISO 6603-2 using injection molded plates measuring 60 x 60 x 3 mm and a test speed of 4.4 m/s, from 20.0 to 60, 0 J. 13. Heterophasic polypropylene composition (K) according to claim 1 or 2, in which the numerical values of Charpy notched impact strength (UCI), puncture energy, soluble fraction content (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method , and the total light transmittance satisfy inequality (I) in this case, the impact strength with a Charpy notch is measured at 23°C and expressed in kJ/m ² , puncture energy is measured at 23°C and expressed in J, the content of the soluble fraction (RF) is indicated in wt. %, A The total light transmittance is indicated in %. 14. Heterophase polypropylene composition (K) according to claim 1 or 2, in which the numerical values of Charpy notched impact strength (UCI), puncture energy, soluble fraction content (SF), determined in accordance with the CRYSTEX QC ISO 6427-B method , and the total light transmittance satisfy inequality (II) in this case, the impact strength with a Charpy notch is measured at -20°C and expressed in kJ/m ² , puncture energy is measured at -20°C and expressed in J, the content of the soluble fraction (RF) is indicated in wt. %, A The total light transmittance is indicated in %. 15. An injection molded product containing a heterophasic propylene-ethylene composition (K) according to any one of the preceding paragraphs. 1-14.