RU2798417C1 - Polypropylene composition with improved manufacturability and impact - Google Patents

Abstract

FIELD: polypropylene products.

SUBSTANCE: present invention is related to a group of inventions: a polypropylene composition for producing packaging products or automotive components; a method for production of a polypropylene composition; product; a packaging item or automotive component; the use of polypropylene composition. This polypropylene composition contains: 60-95 wt.% of the first heterophasic propylene copolymer (A) and 5-40 wt.% of static elastomeric copolymer of ethylene and alpha-olefin (B). The first heterophasic propylene copolymer is characterized by a melt flow index MFI₂ equal to 30-120 g/10 min, and contains 78.0-92.0 wt.% of the crystalline matrix (A1) and 8.0-22.0 wt.% of amorphous propylene-ethylene elastomer (A2). The crystalline matrix (A1) is a homo- or copolymer of propylene, and the specified crystalline matrix corresponds to the crystalline fraction (CF) and contains 0.0-2.0 wt.% of comonomer. The amorphous propylene-ethylene elastomer (A2) optionally contains C₄-C₁₂-alpha-olefin(s) as additional comonomers dispersed in said crystalline matrix (A1), corresponds to the soluble fraction (RF) and contains 15.0-30.0 wt.% of comonomer. Static elastomeric copolymer of ethylene and alpha-olefin (B) is characterized by MFI₂ equal to 0.1-100 g/10 min, and a density of 840-900 kg/m³. The method for producing a polypropylene composition includes the steps of polymerizing the first heterophasic propylene copolymer (A) in a sequential polymerization process in the presence of a single-centre Ziegler-Natta type catalyst system; melt blending of said copolymer (A) with a static elastomeric copolymer of ethylene and an alpha-olefin (B); optionally adding a second heterophasic propylene copolymer (C) polymerized in the presence of a Ziegler-Natta type catalyst system, as well as a reinforcing mineral filler (D) in a melt blending step, followed by solidifying the resulting melt in a strand granulation or underwater granulation step. The product is obtained by injection molding and is characterized by a flexural modulus of 500-1000 MPa, Charpy notched impact strength (NIS) at 23°C of 25.0-95.0 kJ/m², and Charpy NIS at -20°C of 7.0-75.0 kJ/m². The use of a polypropylene composition for production of a packaging article or an automotive component having a wall thickness of at most 1.5 mm in an injection moulding process.

EFFECT: technical result is development of a composition that combines a well-balanced ratio between stiffness and impact strength, low emissions of volatile and hardly volatile substances, and good manufacturability.

15 cl, 1 dwg, 2 tbl, 7 ex

Description

The present invention relates to heterophasic polypropylene compositions containing a propylene homo- or copolymer forming a crystalline fraction in the form of a matrix, and an amorphous propylene-ethylene elastomer in the form of a soluble fraction dispersed in said matrix. The heterophasic polypropylene compositions also contain an elastomeric random copolymer of ethylene and an alpha-olefin. Heterophasic polypropylene compositions have a well balanced ratio between stiffness and toughness, low emissions of volatile and hardly volatile substances and good processability.

Additional Information

Compositions based on propylene copolymers are widely used in several areas of the polymer industry, ranging from advanced packaging solutions to technical applications such as automotive or electronics. Such compositions containing crystalline as well as elastomeric components have a balanced combination of stiffness and toughness, but are often limited in processability. The trend towards lower wall thicknesses, in order to save both energy and weight of the components, requires lower viscosities and correspondingly higher melt flow rates (MFR). The problem, however, is that usually the toughness is greatly reduced when the MFR at a given level of stiffness or elastomer content, respectively, increases. Moreover, both in food packaging and in the automotive sector, the emission of volatile and non-volatile hydrocarbon components (i.e. VOC and FOG levels determined in accordance with VDA 278) should be as low as possible. In addition, existing compositions show higher levels of emissions with increasing MFR. Therefore, there is a need to develop compositions that combine a well-balanced ratio between stiffness and toughness, low emissions of volatile and hardly volatile substances and good processability, ie, a higher melt flow rate (MFR).

Description of the Prior Art

Document EP 2275485 A1 describes heterophasic polypropylene compositions containing (A) from 45 to 70% of the mass. matrix homo - or copolymer of propylene with MFR ₂ (as determined in accordance with ISO 1133 at 230°C and a load of 2.16 kg), at least 80 g/10 min, (B) from 25 to 40% of the mass. an elastomeric propylene-ethylene copolymer having an intrinsic viscosity (IV(IV)) (ISO 1628, with decalin as solvent) ≥3.3 dl/g and an ethylene content of 20 to 50 wt %, (C) 0-15% wt. elastomeric random copolymer of ethylene and alpha-olefin, and (D) 3-25 wt.h. inorganic filler. The corresponding heterophasic polypropylene compositions have a total MFR ₂ of at least 5 g/10 min, a Charpy notched impact strength according to ISO 179/1eA at +23°C of at least 15.0 kJ/m ² , a Charpy notched impact strength according to ISO 179/1eA at -20°C of at least 7.0 kJ/m ² , and a tensile modulus according to ISO 527-3 of at least 1200 MPa. Neither VOC levels nor TLOC levels are specified for the claimed compositions, which furthermore show limited impact resistance at higher MFR ₂ and high stiffness only in combination with fillers.

Document EP 2426171 A1 describes heterophasic polypropylene resins having an MFR ₂ (as determined according to ISO 1133 at 230° C. and a load of 2.16 kg) from 25 to below 100 g/10 min, containing a matrix of crystalline polypropylene homopolymer (A ) and an amorphous propylene-ethylene or propylene-alpha-olefin copolymer phase (B) dispersed in a matrix. These heterophasic polypropylene resins have (i) from 35 to 75% of the mass. a fraction insoluble in p-xylene at 25°C (XCU) with an intrinsic viscosity of less than 1.1 dl/g, determined in accordance with DIN EN ISO 1628-1 and -3, and a melting point greater than 150°C, and (ii) from 25 to 65% of the mass. fraction soluble in p-xylene at 25°C (XCS), with an intrinsic viscosity of 2.0 to 5.0 dl/g, and with an ethylene and/or alpha-olefin content in the range from 40 to 70% of the mass. based on the total weight of the XCS fraction and with no melting point in the analysis of DSC (DSC) in the range between 0 and 300°C. Neither VOC levels nor TLOS levels are specified for the claimed compositions, which also have limited harshness.

EP 2681277 A1 describes polyolefin compositions containing (a) 35-90% by weight, based on the weight of the heterophasic polypropylene composition, a heterophasic polypropylene composition containing (i) 10-50% by weight, based on the weight of the heterophasic polypropylene composition , the first propylene homopolymer (PPH1) having an MFI of ₂ (as measured according to ISO 1133 at 230° C. and a load of 2.16 kg) 30-80 g/10 min, (ii) 20-65 wt%, of based on the weight of the heterophasic polypropylene composition, the second propylene homopolymer (PPH2) having an MFR _{of 2} 100-250 g/10 min, (iii) 5-30% wt., based on the weight of the heterophasic polypropylene composition, the first fraction soluble in cold xylene ( XS1) having an IVXS1 intrinsic viscosity of 2.0-3.0 dl/g, (iv) 5-25 wt. 1.5-2.8 dl/g, provided that IVXS1 ≠ IVXS2, (b) 5-40% wt., based on the weight of the polyolefin composition, inorganic filler, and (c) 5-25% wt., based on the weight of the polyolefin composition, ethylene/1-butene elastomer. Neither VOC levels nor TLOS levels are indicated for the claimed compositions, which show high hardness only in combination with a significant amount of excipients.

Finally, WO 2019042875 A1 describes a polypropylene composition having an MFR _{of 2} (as determined according to ISO 1133 at 230° C. and a load of 2.16 kg) in the range of 5 to 50 g/10 min, moreover, the polypropylene composition contains (a) from 55 to 75 wt.%, based on the total weight of the polypropylene composition, of the crystalline fraction (CF (CF)) as determined by the CRYSTEX QC method, while the crystalline fraction (CF) has (i) a melting point (T _pl ), measured using differential scanning calorimetry (DSC), between 147 and 162°C, and (ii) the content of ethylene <1% of the mass. based on the total mass of the crystalline fraction (CF); and (b) from 25 to 45 wt.%, based on the total weight of the polypropylene composition, soluble fraction (RF (SF)), which is determined by the CRYSTEX QC method, while the soluble fraction (RF) has (i) intrinsic viscosity (IV (IV)) in the range from 1.0 to 2.0 dl/g, and (ii) the content of ethylene in the range from 18 to 40% of the mass. based on the total mass of the soluble fraction (RF). Said polypropylene composition has a ratio of the intrinsic viscosity of the soluble fraction (IV(RF)) to the intrinsic viscosity of the crystalline fraction (CV(CV)) [(CV(RF))/(CV(CV))] in the range from 0.7 to <1 ,2. Neither VOC levels nor TLOS levels are specified for the claimed compositions, which also have limited stringency.

Purpose of the invention

The aim of the present invention is polypropylene compositions combining a well balanced ratio between stiffness and toughness, low emissions of volatile and hardly volatile substances and good processability, i.e., a higher melt flow rate (MFR).

Surprisingly, it has been found that such polypropylene compositions can be obtained by combining from 60 to 95% of the mass. the first heterophasic propylene copolymer (A), containing from 78.0 to 92.0% of the mass. crystalline matrix (A1), which is a homo- or copolymer of propylene, and the specified crystalline matrix corresponds to the crystalline fraction (CF), determined in accordance with the CRYSTEX QC method of ISO 6427-B, and contains from 0.0 to 2.0% of the mass . comonomer, and from 8.0 to 22.0% of the mass. an amorphous propylene-ethylene elastomer (A2), optionally containing C ₄ -C ₈ -alpha-olefin(s) as additional comonomers, dispersed in said crystalline matrix (A1), where (A1) and (A2) add up to 100% wt., and where the specified amorphous propylene-ethylene elastomer (A2) corresponds to the soluble fraction (RF), determined in accordance with the method CRYSTEX QC standard ISO 6427-B, and contains from 15.0 to 30.0% of the mass. comonomer, while the specified heterophasic propylene copolymer is characterized by an index of melt flow MFR ₂ when determined in accordance with ISO1133 at 230°C and a load of 2.16 kg, from 30 to 120 g/10 min, with 5-40% of the mass. elastomeric random copolymer of ethylene and alpha-olefin (B), characterized by MFI ₁ , when determined in accordance with ISO1133 at 190°C and a load of 2.16 kg, from 0.1 to 100 g/10 min and a density in the range from 840 to below 900 kg/m³, where (A) and (B) add up to 100% of the mass.

Optionally, these polypropylene compositions may also contain from 5.0 to 15.0% of the mass. a second heterophasic propylene copolymer (C) having a melt flow index MFR _{of 2} as determined according to ISO1133 at 230° C. and a load of 2.16 kg, from 5 to 25 g/10 min and containing a xylene soluble fraction (XCS ), in the range from 25.0 to 50.0% of the mass. In addition, optionally these polypropylene compositions may contain from 5.0 to 30.0% of the mass. reinforcing mineral filler (D). Preferably, the respective polypropylene compositions have a melt flow index MFR ₂ , as determined according to ISO1133 at 230° C. and a load of 2.16 kg, from 10.0 to 100 g/10 min, and contain a xylene soluble fraction (XCS) , in the range from 20.0 to 50.0% wt., and the specified fraction has a content of comonomers selected from ethylene and/or C ₄ -C ₈ -alpha-olefin(s), in the range from 20.0 to 40, 0% wt. More preferably, the respective polypropylene compositions are characterized by less than 100 µg/g volatile compounds (VOC, VDA 278, October 2011) and less than 200 µg/g low volatile organic condensables (VOC, VDA 278, October 2011).

The invention also relates to a method for the production of such polypropylene compositions by

(i) polymerizing the first heterophasic propylene copolymer (A) in a sequential polymerization process in the presence of a single site catalyst system, and

(ii) melt blending said copolymer (A) with a suitable amount of an elastomeric random copolymer of ethylene and alpha-olefin (B),

(iii) optionally adding a suitable amount of a second heterophasic propylene copolymer (C) polymerized in the presence of a Ziegler-Natta type catalyst system and/or a suitable amount of reinforcing mineral filler (D) in said melt blending step, followed by

(iv) solidifying the resulting melt in a strand granulation or underwater granulation step.

Moreover, the invention relates to injection molded articles containing said polypropylene compositions, which are characterized by a flexural modulus, determined in accordance with ISO 178, in the range from 500 to 1000 MPa, Charpy notched impact strength (NIS) , determined in accordance with ISO 179/1eA at 23°C, greater than 20.0 kJ/m ² , and Charpy NIS, determined in accordance with ISO 179/1eA at -20°C, greater than 6.0 kJ / m ² . The invention also relates to packaging articles or automotive components having a wall thickness of at most 1.5 mm and containing said polypropylene compositions.

The components of said polypropylene compositions as well as the compositions are described in more detail below.

First heterophasic propylene copolymer (A)

The first heterophasic propylene copolymer (A) is present in the polypropylene composition according to the invention in an amount of 60 to 95% by weight, preferably in an amount of 65 to 92% by weight, more preferably in an amount of 70 to 90% by weight.

The specified first heterophasic propylene copolymer (A) contains from 78.0 to 92.0 wt. -%, preferably from 79.0 to 91.0 wt. -%, more preferably from 80.0 to 90.0 wt. crystalline matrix (A1), which is a homo- or copolymer of propylene, and the specified crystalline matrix corresponds to the crystalline fraction (CF), determined in accordance with the CRYSTEX QC method of ISO 6427-B, and contains from 0.0 to 2.0% of the mass ., preferably from 0.5 to 1.8 wt. -%, more preferably from 0.7 to 1.6% of the mass. comonomer. Said comonomer is preferably ethylene. The crystalline fraction (IF) preferably has an intrinsic viscosity (IV), determined according to ISO1628, from 0.6 to 2.0 dl/g, more preferably from 0.8 to 1.8 dl/g, most preferably from 0 .9 to 1.6 dl/g.

The first heterophasic propylene copolymer (A) also contains from 8.0 to 22.0 wt. -%, preferably from 9.0 to 21.0 wt. -%, more preferably from 10.0 to 20.0 wt. amorphous propylene-ethylene elastomer (A2), optionally containing C ₄ -C ₁₂ alpha-olefin(s) as additional comonomers, dispersed in said crystalline matrix (A1), said amorphous propylene-ethylene elastomer (A2) corresponding to the soluble fraction (RF), determined in accordance with the method CRYSTEX QC standard ISO 6427-B, and contains from 15.0 to 30.0% wt., preferably from 16.5 to 28.0 wt.%, more preferably from 17.5 up to 26.0% wt. comonomer. Said comonomer is ethylene and/or one or more C ₄ -C ₈ alpha-olefins. Preferably said comonomer is ethylene. The soluble fraction (SF) preferably has an intrinsic viscosity (IV), determined according to ISO1628, from 1.8 to 3.5 dl/g, more preferably from 2.0 to 3.2 dl/g, most preferably from 2 .1 to 3.1 dl/g.

The respective amounts of the crystalline matrix (A1) and the amorphous propylene-ethylene elastomer (A2) add up to 100% by weight.

According to a preferred embodiment, the first heterophasic propylene copolymer (A) has an MFR of ₂ , as determined according to ISO1133 at 230°C and a load of 2.16 kg, from 20 to 120 g/10 min, preferably from 35 up to 110 g/10 min, more preferably from 38 to 100 g/10 min. In accordance with another preferred embodiment, the first heterophasic propylene copolymer (A) has a hexane-soluble fraction in accordance with the FDA method (C6FDA) in the range from 0.8 to 2.8% wt., preferably in the range from 1.0 to 2 ,3% wt., more preferably in the range from 1.1 to 2.0% of the mass.

The heterophasic polypropylene composition may have a xylene cold soluble fraction (XCS) in the range of 8.0 to 22.0 wt%, preferably in the range of 9.0 to 21.0 wt%, more preferably in the range of 10 .0 to 20.0% wt. The comonomer content of said xylene cold soluble (XCS) fraction of the heterophasic polypropylene composition may be in the range of 15.0 to 30.0 wt%, preferably in the range of greater than 16.5 to 28.0 wt%, more preferably in the range from 17.5 to 26.0% of the mass. The intrinsic viscosity (XCS) of said cold xylene soluble (XCS) fraction of the heterophasic polypropylene composition may be in the range of 1.8 to 3.5 dl/g, preferably in the range of 2.0 to 3.2 dl /g, more preferably in the range from 2.1 to 3.1 dl/g.

The melting temperature, T _pl (DSC), the inventive polymer may be in the range from 145 to 162°C, preferably in the range from 150 to 160°C, more preferably in the range from 152 to 158°C. The crystallization temperature T _cr (DSC) of the inventive polymer may be in the range from 103 to 123°C, preferably in the range from 108 to 120°C, more preferably in the range from 110 to 118°C.

The crystalline matrix (A1) of the first heterophasic propylene copolymer (A) is a propylene homo- or copolymer similar to a propylene random copolymer. It may contain alpha-olefins selected from ethylene and C ₄ -C ₈ alpha-olefins, preferably from ethylene or 1-butene. In a preferred embodiment, the crystalline matrix contains ethylene as a comonomer. In an equally preferred embodiment, the crystalline matrix is a propylene homopolymer. The crystalline matrix may suitably contain comonomer as described above in an amount of 0.0 to 2.0% by mass, preferably in an amount of 0.3 to 1.8% by mass, more preferably in an amount of 0.5 to 1 .6% wt.

The crystalline matrix forms from 78.0 to 95.0 wt%, preferably from 80.0 to 93.0 wt%, more preferably from 81.0 to 92.0 wt%. the first heterophasic propylene copolymer (A).

The melt flow index MFR ₂ , when determined according to ISO1133 at 230° C. and a load of 2.16 kg, of the crystal matrix (A1) can be in the range of 80 to 200 g/10 min, preferably in the range of 90 to 180 g /10 min, more preferably in the range from 95 to 170 g/10 min.

The amorphous propylene-ethylene elastomer (A2) present as dispersed particles in the crystalline matrix (A1) of the first heterophasic propylene copolymer (A) forms from 5.0 to 22.0% by mass, preferably from 7.0 to 20.0 % wt., more preferably from 8.0 to 19.0% wt. said heterophasic propylene copolymer.

The amorphous propylene-ethylene elastomer (A2) is preferably characterized by the soluble fraction according to the CRYSTEX QC method of ISO6427-B and can be in the range from 8.0 to 22.0% by weight, preferably in the range from 9.0 to 21.0 % wt., more preferably in the range from 10.0 to 20.0% wt.

The amorphous propylene-ethylene elastomer (A2) may also contain alpha-olefins selected from C ₄ -C ₈ alpha-olefins, preferably 1-butene or 1-hexene. Preferably, the amorphous propylene-ethylene elastomer (A2) contains ethylene and 1-butene as comonomers. In a particularly preferred embodiment, the amorphous propylene-ethylene elastomer (A2) contains propylene and ethylene, more preferably consists of propylene and ethylene, as the only comonomers.

According to a preferred embodiment, the first heterophasic propylene copolymer (A) is produced in a sequential polymerization process in the presence of a single site catalyst system. Preferably, said catalyst system comprises an asymmetric metallocene catalyst complex and one or more co-catalysts.

Elastomeric random copolymer of ethylene and alpha-olefin (B)

Elastomeric random copolymer of ethylene and alpha-olefin (B) is present in the polypropylene composition according to the invention in an amount of from 5 to 40 wt. -%, preferably in an amount of from 8 to 35 wt. -%, more preferably in an amount of from 10 to 30 wt.%.

Preferred elastomeric random copolymers of ethylene and alpha-olefin (B) are elastomeric copolymers of ethylene and C ₄ -C ₈ -alpha-olefins, like ethylene-1-butene copolymers, ethylene-1-hexene copolymers or ethylene-1-octene copolymers. More preferred ethylene/alpha-olefin random copolymers are ethylene-1-butene copolymers and ethylene-1-octene copolymers. Most preferred are ethylene-1-octene copolymers.

The elastomeric ethylene-alpha-olefin random copolymer (B) has an MFR ₁ , as determined according to ISO1133 at 190° C. and a load of 2.16 kg, from 0.1 to 100 g/10 min, preferably from 0.2 to 50 g/10 min, more preferably 0.5 to 20 g/10 min, and a density in the range of 840 to below 900 kg/m ³ , preferably in the range of 850 to below 890 kg/m ³ , more preferably in the range from 852 to below 880 kg/m ³ .

According to a preferred embodiment, the elastomeric ethylene/alpha-olefin (B) random copolymer is an ethylene-1-octene copolymer having an octene content of at least 20 wt%, preferably about 25-50 wt%, more preferably about 30-45% wt., and the density is less than 880 kg/m ³ , preferably less than 870 kg/m ³ .

According to another preferred embodiment, the elastomeric ethylene-alpha-olefin (B) random copolymer is characterized by one or more glass transition temperatures, as determined by differential scanning calorimetry (DSC) or dynamic mechanical thermal analysis (DMTA), ranging from -90 to -35°C, preferably in the range from -85 to -40°C, more preferably in the range from -80 to -45°C.

According to another preferred embodiment, the elastomeric ethylene-alpha-olefin random copolymer (B) has a melting point, as determined by differential scanning calorimetry (DSC), in the range of 20 to 65°C, preferably in the range of 25 to 60°C , more preferably in the range from 30 to 55°C.

Preferably, the elastomeric ethylene-alpha-olefin random copolymer (B) is based on solution polymerization using a single site catalyst. The production of elastomeric ethylene-1-octene copolymers is described in detail in Chum SP, Kao CI, Knight GW, "Structure, properties and preparation of polyolefins produced by single-site technology"; in "Metallocene based Polyolefins" - Volume 1, Scheirs J, Kaminsky W Eds, John Wiley and Sons Ltd, Chichester (West Sussex, England), 2000 pp. 262-264. On the other hand, commercially available elastomeric ethylene-1-octene copolymers can be used. Suitable grades are, for example, provided by the Engage grade series from DOW Chemical, USA, the Queo grade series from Borealis AG, Austria, and the Exact grade series from ExxonMobil, USA.

Second heterophasic propylene copolymer (C)

If it is present, then the amount of the second heterophasic propylene copolymer (C) in the heterophasic polypropylene composition according to the invention may be in the range from 5.0 to 15.0 wt%, preferably in the range from 7.0 to 13.0 wt%, more preferably in the range of 8.0 to 12.0% by weight, based on the total weight of the heterophasic polypropylene composition.

The second heterophasic propylene copolymer (C) contains comonomers, preferably alpha-olefins, selected from ethylene and C ₄ -C ₈ alpha-olefins, preferably from ethylene, 1-butene or 1-hexene. In a preferred embodiment, the second heterophasic propylene copolymer contains ethylene and 1-butene as comonomer. In a particularly preferred embodiment, the second heterophasic propylene copolymer contains one ethylene as the sole comonomer.

The melt flow index MFR ₂ , when determined in accordance with ISO1133 at 230°C and a load of 2.16 kg, of the second heterophasic propylene copolymer (C) may be in the range from 5.0 to 25.0 g/10 min, preferably in in the range of 7.0 to 20.0 g/10 min, more preferably in the range of 8.0 to 15.0 g/10 min.

The second heterophasic propylene copolymer has a xylene cold soluble (XCS) fraction in the range of 25.0 to 50.0 wt%, preferably in the range of 28.0 to 45.0 wt%, more preferably in the range of 30 .0 to 40.0% wt.

The content of comonomer in the xylene cold-soluble fraction, C ₂ (XCS), of the second heterophasic propylene copolymer may be in the range from 20.0 to 60.0 wt. -%, preferably in the range from 26.0 to 55.0 wt. , more preferably in the range from 30.0 to 50.0% of the mass.

The intrinsic viscosity of the xylene cold soluble fraction, IV(XCS), may be in the range of 1.0 to 10.0 dl/g, preferably in the range of 1.2 to 9.0 dl/g, more preferably in the range of 1.4 to 8.0 dl/g.

According to a preferred embodiment, the second heterophasic propylene copolymer (C) is produced in a sequential polymerization process in the presence of a Ziegler-Natta type catalyst system. Preferably, said catalyst system comprises a self-supporting Ziegler-Natta catalyst comprising a magnesium compound, a titanium compound and a non-phthalic internal electron donor (ID), an aluminum compound co-catalyst and an external silane donor (ED).

Reinforcing mineral filler (D)

If present, the amount of reinforcing mineral filler (D) in the heterophasic polypropylene composition according to the invention may be in the range from 5.0 to 30.0% wt., preferably in the range from 7.0 to 25.0% wt., more preferably in the range from 8.0 to 20.0% of the mass.

According to a preferred embodiment of the present invention, the reinforcing mineral filler (D) is selected from the group consisting of talc, mica, wollastonite and calcium carbonate. More preferably, the reinforcing mineral filler (D) is talc.

According to another preferred embodiment of the present invention, the reinforcing mineral filler (D) used for the polypropylene composition of the invention has a median particle size (D ₅₀ ) of 0.5-15 µm and an upper fraction (D ₉₅ ) of 1-50 µm. More preferably, the reinforcing mineral filler (D) has a median particle size (D ₅₀ ) of 0.8-12 µm and an upper fraction (D ₉₅ ) of 1.0-30 µm, most preferably a median particle size (D ₅₀ ) of 1.5-10 µm, and the upper fraction (D ₉₅ ) 2.0-20 µm.

A common method for measuring the particle size distribution is the laser diffraction method, by which the median particle size (D ₅₀ ) and the upper fraction (D ₉₅ ) can be calculated. An alternative way to determine the upper fraction is to determine the fraction of filler particles having a diameter above a certain limit, that is, the so-called sieve residue.

The inventive polypropylene composition

A suitable polypropylene composition comprising a first heterophasic propylene copolymer (A), an elastomeric ethylene-alpha-olefin random copolymer (B), and optionally a second heterophasic propylene copolymer (C) and/or a reinforcing mineral filler (D) as defined above, can also be characterized by common properties.

Preferably, the corresponding polypropylene composition has a melt flow index MFR ₂ , as determined in accordance with ISO1133 at 230°C and a load of 2.16 kg, from 10.0 to 100 g/10 min, more preferably from 13.0 to 75 g/ 10 min, most preferably 15.0 to 50 g/10 min. Equally preferably, the respective polypropylene composition contains a xylene cold soluble (XCS) fraction in the range of 20.0 to 50.0 wt%, more preferably in the range of 24.0 to 45.0 wt%, most preferably in the range from 26.0 to 42.0% of the mass. Said cold xylene soluble (XCS) fraction may have a comonomer content selected from ethylene and/or C ₄ -C ₈ alpha-olefin(s) in the range of 20.0 to 40.0% wt., preferably in the range from 22.0 to 38.0% wt., more preferably in the range from 24.0 to 36.0% of the mass.

According to a particularly preferred embodiment, the corresponding polypropylene composition is characterized by a level of less than 100 µg/g, preferably less than 80 µg/g, more preferably less than 60 µg/g of volatile compounds (VOC, VDA 278, October 2011) and a level of less than 200 µg/g, preferably less than 175 µg/g, more preferably less than 150 µg/g of low volatile organic condensables (TLOS, VDA 278, October 2011). The content of VOCs and TLOCs is usually determined on pellets immediately after their production without any specific emission control measures such as aeration.

The polypropylene composition according to the invention may also contain conventional additives in an amount of up to 5.0 wt. -%, preferably in an amount of up to 2.0 wt. -%, more preferably in an amount of up to 1.0 wt. Examples of additives include, but are not limited to, stabilizers such as antioxidants (eg, hindered phenols, phosphites/phosphonites, sulfur containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers, or mixtures thereof); metal deactivators (eg Irganox® MD 1024) or UV stabilizers (eg hindered amine light stabilizers). Other typical additives are modifiers such as nucleating agents (eg sodium benzoate or 2,2'-methylene-bis(4,6-di-tert-butylphenyl)-sodium phosphate), antistatic or antifogging agents (eg ethoxylated amines). and glycerol amides or esters), acid scavengers (eg Ca-stearate), and blowing agents for foaming. Other modifiers are lubricants and resins (e.g. ionomer waxes, polyethylene and ethylene copolymer waxes, Fischer-Tropsch waxes, montan waxes, fluorine compounds or paraffin waxes) as well as slip and antiblocking agents (e.g. erucamide, oleamide, talc). , natural silica and synthetic silica or zeolites), as well as mixtures thereof.

Mode of production

The method for the production of a polypropylene composition according to the invention includes the following technological steps:

(i) polymerizing the first heterophasic propylene copolymer (A) in a sequential polymerization process, preferably in the presence of a single site catalyst system, and

(ii) melt blending said copolymer (A) with a suitable amount of an elastomeric random copolymer of ethylene and alpha-olefin (B),

(iii) optionally adding a suitable amount of a second heterophasic propylene copolymer (C) polymerized in the presence of a Ziegler-Natta type catalyst system, as well as a suitable amount of reinforcing mineral filler (D) in said melt blending step, followed by

(iv) solidifying the resulting melt in a strand granulation or underwater granulation step.

Step (i) of said process for producing the polypropylene composition of the invention is a process for polymerizing the first heterophasic propylene copolymer (A). This is preferably achieved by sequential polymerization in the presence of a single site catalyst system, where

- the first polypropylene fraction, which is a propylene homopolymer or a propylene-ethylene random copolymer, having a comonomer content of from 0.0 to 1.0% wt., is obtained in a reactor with a bulk phase in the first stage of polymerization in a loop reactor,

- optionally transferring said first polypropylene fraction to a second polymerization stage, in which a second polypropylene fraction, which is a propylene homopolymer or a propylene-ethylene random copolymer having a comonomer content of 0.0 to 1.0 wt %, is produced in a gas phase reactor (GPR1), withdraw from said bulk phase reactor or optionally from said GPR1 the crystalline matrix (A1) of the first heterophasic propylene copolymer (A),

- the crystalline matrix (A1) is transferred to the second (optionally third) polymerization stage, in which the amorphous propylene-ethylene elastomer (A2) having a comonomer content (C ₂ in RF) from 15.0 to 30.0% wt., for example, from 16.5 to 28.0% of the mass. or from 17.5 to 26.0% wt., obtained in a gas-phase reactor (GPR2),

- a mixture of these two, optionally three polymers, optionally subjected to a deactivation and purification step, followed by compounding and granulation.

The first heterophasic propylene copolymer (A) is usually and preferably produced by a multi-stage polymerization process well known in the art. A preferred multi-stage process is a gas phase loop process such as the process developed by Borealis A/S, Germany (known as the BORSTAR® technology) described for example in patent literature such as EP-A-0887379 or WO 92/12182.

The invention preferably relates to the copolymerization of propylene, ethylene and optionally other comonomers as described above and below in at least two, optionally three process steps so as to form a heterophasic polypropylene composition. Preferably propylene and ethylene are the only monomers used.

Ideally, the process of the invention uses two, preferably three, main reactors, a first bulk reactor, an optional first gas phase reactor, and a second gas phase reactor.

The process can also use a prepolymerization step which takes place in a separate reactor before the two (three) main reactors.

The first heterophasic propylene copolymer (A) is preferably produced with a single site catalyst system, more preferably with a single site catalyst system containing an asymmetric metallocene catalyst complex and cocatalysts.

Single site catalytic system

Preferred metallocene catalyst complexes include:

rac-dimethylsilandiyl-bis[2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylidene-1-yl]zirconium dichloride,

rac-anti-dimethylsilandiyl[2-methyl-4-(4'-tert-butylphenyl)-inden-1-yl][2-methyl-4-(4'-tert-butylphenyl)-5-methoxy-6-tert -butylinden-1-yl]zirconium dichloride,

rac-anti-dimethylsilandiyl[2-methyl-4-(4'-tert-butylphenyl)-inden-1-yl][2-methyl-4-phenyl-5-methoxy-6-tert-butylinden-1-yl] - zirconium dichloride,

rac-anti-dimethylsilandiyl[2-methyl-4-(3',5'-tert-butyl-phenyl)-1,5,6,7-tetrahydro-s-im-indacen-1-yl][2-methyl-4 -(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

rac-anti-dimethylsilandiyl[2-methyl-4,8-bis-(4'-tert-butyl-phenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl- 4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

rac-anti-dimethylsilandiyl[2-methyl-4,8-bis-(3',5'-dimethyl-phenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl -4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

rac-anti-dimethylsilandiyl[2-methyl-4,8-bis-(3',5'-dimethyl-phenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-methyl -4-(3',5'-di-tert-butylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride.

Particularly preferred is rac-anti-dimethylsilane-diyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][ 2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride.

cocatalyst

For the formation of catalytically active samples, it is usually necessary to use a co-catalyst, as is well known in the art.

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

The aluminoxane cocatalyst may be a cocatalyst of formula (II):

(II),

(II)

where n is from 6 to 20 and R is as follows.

Alumoxanes are obtained by partial hydrolysis of organoaluminum compounds, for example compounds of the formula AlR ₃ , AlR ₂ Y and Al ₂ R ₃ Y ₃ , where R may be, for example, C ₁ -C ₁₀ -alkyl, preferably C ₁ -C ₅ - alkyl or C ₃ -C ₁₀ -cycloalkyl, C ₇ -C ₁₂ -arylalkyl or -alkylaryl and/or phenyl or naphthyl, and where Y can represent a hydrogen atom, a halogen atom, preferably a chlorine or bromine atom, or C ₁ -C _{a 10} -alkoxy group, preferably a methoxy or ethoxy group. The final oxygenated alumoxanes are usually not pure compounds, but are mixtures of oligomers of formula (II).

The preferred alumoxane is methylalumoxane (MAO). Since the alumoxanes used as cocatalyst according to the invention are not pure compounds due to their method of preparation, the molarity of the alumoxane solutions is calculated from their aluminum content.

A boron-containing cocatalyst may also be used in combination with an aluminoxane cocatalyst.

The catalyst complex ideally contains a co-catalyst, and some boron-containing co-catalysts are preferred. Particularly preferred borates used in the invention thus contain trityl, ie triphenylcarbenium ion. Therefore, the use of Ph ₃ CB(PhF ₅ ) ₄ and its analogues is particularly useful.

The catalyst system of the invention is used in supported form. The particulate carrier material used is silica or a mixed oxide such as (silicon dioxide)-(alumina), especially silica.

The use of silicon dioxide as a carrier is preferred. Those skilled in the art are aware of the techniques required for applying a metallocene catalyst.

In a preferred embodiment, the catalyst system corresponds to ICS3, which is described in document EP19177308.4.

Step (ii) of said process for producing the polypropylene composition of the invention is a melt blending process for combining a first heterophasic propylene copolymer (A) with an elastomeric ethylene-alpha-olefin random copolymer (B). The melt mixing process is carried out in any suitable melt mixing apparatus. Devices suitable for this process step (ii) are batch and continuous kneaders, twin screw extruders and single screw extruders with special mixing sections, Farell kneaders and Buss mixer type kneaders. Temperature, rotation speed, throughput and residence time must be chosen so that a sufficiently high degree of homogenization is achieved.

Typically, for this process step (ii), co-rotating, intermeshing twin screw extruders with dedicated mixing sections are used. Typical melt mixing temperatures are in the range of 200 to 280°C. The extruder typically includes a feed zone, a melt zone, a mixing zone and optionally a die zone, and typically has a length to diameter ratio, L/D, up to 60:1, preferably up to 40:1.

Additionally, additives such as stabilizers or nucleating agents may be added during the melt mixing step.

Optionally, according to step (iii), in said melt blending step, a suitable amount of the second heterophasic propylene copolymer (C) polymerized in the presence of a Ziegler-Natta type catalyst system, as well as a suitable amount of reinforcing mineral filler (D) can be added.

Ziegler-Natta catalytic system

For the production of the second heterophasic propylene copolymer (C), the same processes as described for the first heterophasic propylene copolymer (A) can be used. The Ziegler-Natta type catalyst system used for the polymerization of the second heterophasic propylene copolymer (C) preferably comprises a self-supporting Ziegler-Natta catalyst containing a magnesium compound, a titanium compound and a non-phthalic internal electron donor (ID), an aluminum compound co-catalyst, and external donor (ED), which is a silane.

Typically, a Ziegler-Natta polymerization catalyst contains one or more Group 4-6 transition metal (TM) compounds as defined in the IUPAC 2013 version, such as titanium, as well as a Group 2 metal compound, such as a magnesium compound, and an internal donor (ID) .

It is also preferred that the catalyst components are not supported on an external support and the catalyst is prepared by an emulsion curing or precipitation process, as is well known to those skilled in the art of catalyst preparation.

More preferably, a specific type of Ziegler-Natta catalyst is present in the process of the invention. In this particular type of Ziegler-Natta catalyst, it is important that the internal donor is a non-phthalic compound. Preferably, no phthalate compound is used in the preparation of the entire particular type of Ziegler-Natta catalyst, hence the finished particular type of Ziegler-Natta catalyst does not contain any phthalic compound. Thus, a particular type of Ziegler-Natta catalyst is free of phthalic compounds. As a result, the polymer produced by the process of the invention is free of phthalic compounds.

Typically, a particular type of Ziegler-Natta catalyst contains an internal donor (ID) which is selected as a non-phthalic compound, whereby a particular type of Ziegler-Natta catalyst is completely free of phthalic compounds. In addition, a particular type of Ziegler-Natta catalyst may be a solid catalyst, preferably free of any external carrier material such as silica or MgCl ₂ , and hence the solid catalyst is self-supporting.

A solid catalyst can be prepared using the following general procedure:

a) solution preparation:

a1) at least an alkoxy compound of a Group 2 metal (Ax) which is a reaction product of a Group 2 metal compound and an alcohol (A) containing, in addition to the hydroxyl moiety, at least one ether moiety, optionally in an organic liquid reaction medium; or

a2) at least an alkoxy compound of a Group 2 metal (Ax') which is a reaction product of a Group 2 metal compound and an alcohol mixture of an alcohol (A) and a monohydric alcohol (B) of the formula ROH, optionally in an organic liquid reaction medium; or

a3) mixtures of a Group 2 metal alkoxy compound (Ax) and a Group 2 metal alkoxy compound (Bx) which is a reaction product of a Group 2 metal compound and a monohydric alcohol (B), optionally in an organic liquid reaction medium; or

a4) Group 2 metal alkoxy compounds of the formula M(OR ₁ ) _n (OR ₂ ) _m X _2-nm or mixtures of group 2 metal alkoxides of the formulas M(OR ₁ ) _n' X _2-n' and M(OR ₂ ) _{m '} X _2-m' where M is a Group 2 metal, X is a halogen atom, R ₁ and R ₂ are different alkyl groups having 2 to 16 carbon atoms, and 0<n<2, 0<m <2 and n+m+(2-nm)=2, provided that n and m do not have the value 0 at the same time, 0<n'<2 and 0<m'<2; And

b) adding said solution from step a) to at least one Group 4-6 transition metal compound, and

c) obtaining particles of the solid component of the catalyst,

and adding a non-phthalic internal electron donor (ID) at least one step before step c).

The internal donor (ID) or its precursor is preferably added to the solution of step a) or to the transition metal compound before adding the solution of step a). According to the procedure described above, a solid catalyst can be obtained by a precipitation process or by emulsion curing, depending on the physical conditions, especially the temperature used in steps b) and c). An emulsion is also referred to as a two-phase liquid-liquid system. In both methods (precipitation or emulsion curing), the catalyst chemistry is the same. In the precipitation method, the solution of step a) is combined with at least one transition metal compound of step b) and the entire reaction mixture is kept at least 50°C, more preferably at a temperature in the range from 55 to 110°C , more preferably in the range from 70 to 100°C, to ensure complete precipitation of the catalyst component in the form of solid particles of the catalyst component (step c).

In the method for curing the emulsion in step b), the solution of step a) is generally added to at least one transition metal compound at a lower temperature, for example from -10 to below 50° C., preferably from -5 to 30° C. While stirring the emulsion, the temperature is usually maintained in the range from -10 to below 40°C, preferably from -5 to 30°C. Drops of the dispersed phase of the emulsion form the composition of the active catalyst. The curing (step c) of the droplets is suitably carried out by heating the emulsion to a temperature of 70 to 150°C, preferably 80 to 110°C. The catalyst obtained by the emulsion curing method is preferably used in the present invention. In step a), a solution of a2) or a3) is preferably used, i.e. a solution of (Ax') or a solution of a mixture of (Ax) and (Bx).

Preferably the Group 2 metal is magnesium. Magnesium alkoxy compounds (Ax), (Ax'), (Bx) can be prepared in situ in the first step of the catalyst preparation process, step a), by reacting a magnesium compound with an alcohol(s) as described above. Another option is to prepare said magnesium alkoxy compounds separately, or these compounds may even be commercially available as already prepared magnesium alkoxy compounds and can be used as such in the process for preparing the catalyst of the invention.

Illustrative examples of alcohols (A) are glycol monoethers. Preferred alcohols (A) are C ₂ -C ₄ glycol monoethers in which the ether moieties contain 2 to 18 carbon atoms, preferably 4 to 12 carbon atoms. Preferred examples are 2-(2-ethyl-hexyloxy)ethanol, 2-butyloxyethanol, 2-hexyloxyethanol and 1,3-propylene glycol monobutyl ether, 3-butoxy-2-propanol, wherein 2-(2-ethylhexyloxy)ethanol and monobutyl ether1 ,3-propylene glycol, 3-butoxy-2-propanol are particularly preferred.

Exemplary monohydric alcohol (B) has the structural formula ROH, wherein R is a straight or branched C ₂ -C ₁₆ alkyl radical, preferably a C ₄ -C ₁₀ alkyl radical, more preferably a C ₆ -C ₈ alkyl radical. The most preferred monohydric alcohol is 2-ethyl-1-hexanol or octanol.

Preferably a mixture of alkoxy compounds of Mg (Ax) and (Bx) or a mixture of alcohols (A) and (B), respectively, is used and used in a molar ratio of Bx:Ax or B:A from 10:1 to 1:10, more preferably 6:1 to 1:6, even more preferably 5:1 to 1:3, most preferably 5:1 to 3:1.

The magnesium alkoxy compounds may be the reaction product of the alcohol(s) defined above, and the magnesium compound may be selected from dialkyl magnesium, alkyl magnesium alkoxide, magnesium dialkoxide, alkoxy magnesium halide, and alkyl magnesium halide. In addition, magnesium dialkoxide, magnesium diaryloxide, magnesium aryloxyhalide, magnesium aryloxide, and magnesium alkylaryloxide can be used. The alkyl groups in the magnesium compound may be the same or different C ₁ -C ₂₀ alkyl groups, preferably C ₂ -C ₁₀ alkyl groups. Typical alkyl alkoxy magnesium compounds, when used, are magnesium butoxide, butyl magnesium pentoxide, octyl magnesium butoxide, and octyl magnesium octoxide. Preferably, dialkylmagnesium is used. The most preferred dialkylmagnesium is butyloctylmagnesium or butylethylmagnesium.

It is also possible that the magnesium compound reacts in addition to the alcohol (A) and alcohol (B) with a polyhydric alcohol (C) of the formula R″(OH) _m to give said magnesium alkoxide compound. Preferred polyhydric alcohols, if used, are those in which R" is a linear, cyclic or branched C ₂ -C ₁₀ hydrocarbon residue and m is an integer from 2 to 6.

The magnesium alkoxy compounds of step a) are thus selected from the group consisting of magnesium dialkoxides, diaryloxy magnesium halides, alkyloxy magnesium halides, aryloxy magnesium halides, alkyl magnesium alkoxides, aryl magnesium alkoxides and alkyl magnesium aryl oxides, or a mixture of magnesium dihalide and magnesium dialkoxide.

The solvent used to prepare the present catalyst may be selected from aromatic and aliphatic linear, branched and cyclic hydrocarbons having from 5 to 20 carbon atoms, more preferably from 5 to 12 carbon atoms, or mixtures thereof. Suitable solvents include benzene, toluene, cumene, xylene, pentane, hexane, heptane, octane and nonane. Hexanes and pentanes are particularly preferred.

The reaction to obtain a magnesium alkoxy compound can be carried out at a temperature of 40 to 70°C. One skilled in the art will know how to select the most appropriate temperature depending on the Mg compound and alcohol(s) used.

The Group 4-6 transition metal (TM) compound as defined in IUPAC version 2013 is preferably a titanium compound, most preferably a titanium halide such as TiCl ₄ . The non-phthalic internal donor (ID) used in the preparation of the specific type of Ziegler-Natta catalyst used in the present invention is preferably selected from (di)esters of non-phthalic carboxylic (di)acids, 1,3-diesters, derivatives thereof and mixtures thereof. A particularly preferred donor is a diester of monounsaturated non-phthalic dicarboxylic acids, in particular an ester belonging to the group consisting of malonates, maleates, succinates, citraconates, glutarates, cyclohexene-1,2-dicarboxylates and benzoates, as well as their derivatives and/or mixtures thereof. Preferred examples are, for example, substituted maleates and citraconates, most preferably citraconates. Hereinafter, the term "derivative" includes substituted compounds.

In an emulsion curing process, a two-phase liquid-liquid system can be formed by simply mixing and optionally adding (additional) solvent(s) and/or additives such as a turbulence minimizing agent (TMA) and/or an emulsifying agent and/or an emulsion stabilizer such as a surfactant, which are used in a manner known in the art. These solvents and/or additives are used to facilitate the formation of the emulsion and/or to stabilize it.

Preferably the surfactants are acrylic or methacrylic polymers. Particularly preferred are linear C ₁₂ -C ₂₀ -(meth)acrylates such as poly(hexadecyl)methacrylate and poly(octadecyl)methacrylate and mixtures thereof. The turbulence minimizing agent (TMA), if used, is preferably selected from polymers of C6-C20 α-olefin monomers such as polyoctene, polynonene, polydecene, polyundecene or polydodecene, or mixtures thereof. Polydecene is most preferred.

The particulate product obtained by the emulsion precipitation or solidification process may be washed at least once, preferably at least two times, most preferably at least three times. Washing can be carried out with an aromatic and/or aliphatic hydrocarbon, preferably with toluene, heptane or pentane. It is also possible to flush with TiCl ₄ , optionally mixed with an aromatic and/or aliphatic hydrocarbon. Wash liquids may also contain donors and/or Group 13 compounds such as trialkylaluminums, halogenated alkylaluminum compounds or alkoxyaluminum compounds. Aluminum compounds can also be added during catalyst synthesis. The catalyst may then be dried, for example by evaporation or nitrogen flushing, or it may be suspended in an oily liquid without any drying step.

The particular type of Ziegler-Natta catalyst finally obtained is, if desired, in the form of particles having typically an average particle size in the range of 5 to 200 µm, preferably 10 to 100 µm. The particles are generally compact, have low porosity and generally have a surface area below 20 g/m ² , more preferably below 10 g/m ² . Typically, the amount of Ti present in the catalyst is in the range of 1 to 6 wt%, the amount of Mg is in the range of 10 to 20 wt%, and the amount of internal donor present in the catalyst is in the range of 10 to 40 % wt. from the composition of the catalyst. A detailed description of the preparation of the catalysts used in the present invention is disclosed in WO 2012/007430, EP 2610271 and EP 2610272, which are incorporated herein by reference.

The external donor (ED) is preferably present as an additional component in the polymerization process of the present invention. Suitable external donors (ED) include certain silanes, ethers, esters, amines, ketones, heterocyclic compounds, and mixtures thereof. The use of a silane is particularly preferred. Most preferably, silanes of general formula (I) are used:

R ^a _p R ^b _q Si(OR ^c ) _(4-pq) (I),

where R ^a , R ^b and R ^c denote a hydrocarbon radical, in particular an alkyl or cycloalkyl group, and where p and q are numbers ranging from 0 to 3, and their sum (p + q) is equal to or less than 3 The substituents R ^a , R ^b and R ^c may be selected independently of each other and may be the same or different. Specific examples of silanes according to formula (I) are (tert-butyl) ₂ Si(OCH ₃ ) ₂ , (cyclohexyl)-(methyl)-Si(OCH ₃ ) ₂ , (phenyl) ₂ Si(OCH ₃ ) ₂ and (cyclopentyl) ₂ Si(OCH ₃ ) ₂ . Another most preferred silane is a silane according to the general formula (II):

Si(OCH ₂ CH ₃ ) ₃ (NR ³ R ⁴ ) (II),

where R ³ and R ⁴ may be the same or different and mean a linear, branched or cyclic hydrocarbon group having from 1 to 12 carbon atoms. It is particularly preferred that R ³ and R ⁴ are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, iso-propyl, iso-butyl, iso-pentyl, t-butyl, t -amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl. Most preferably, ethyl is used.

Typically, in addition to a Ziegler-Natta catalyst or a specific type of Ziegler-Natta catalyst and an optional external donor (ED), a co-catalyst must be present in the polymerization process of the invention. The co-catalyst is preferably a Group 13 compound (IUPAC, version 2013) such as an aluminum compound, eg an organoaluminum compound or an aluminum halide compound. An example of a suitable organoaluminum compound is an alkylaluminum or alkylaluminum halide. Accordingly, in one particular embodiment, the co-catalyst (Co) is trialkylaluminum, eg, triethylaluminum (TEAL), dialkylaluminum chloride or alkylaluminum dichloride, or mixtures thereof. In one particular embodiment, the cocatalyst (Co) is triethylaluminum (TEAL).

Typically, the molar ratio between cocatalyst (Co) and external donor (ED), [Co/ED], and/or the molar ratio between cocatalyst (Co) and transition metal (TM), [Co/TM], is carefully chosen for each process. The molar ratio between cocatalyst (Co) and external donor (ED), [Co/ED], may suitably be in the range of 2.5 to 50.0 mol/mol, preferably in the range of 4.0 to 35.0 mol /mol, more preferably in the range from 5.0 to 30.0 mol/mol. A suitable lower limit may be 2.5 mol/mol, preferably 4.0 mol/mol, more preferably 5.0 mol/mol. A suitable upper limit may be 50.0 mol/mol, preferably 35.0 mol/mol, more preferably 30.0 mol/mol. The specified lower and upper interval values are included.

The molar ratio between the co-catalyst (Co) and the transition metal (TM) [Co/TM] can respectively be in the range from 20.0 to 500.0 mol/mol, preferably in the range from 50.0 to 400.0 mol/mol, more preferably in the range of 100.0 to 300.0 mol/mol. A suitable lower limit may be 20.0 mol/mol, preferably 50.0 mol/mol, more preferably 100.0 mol/mol. A suitable upper limit may be 500.0 mol/mol, preferably 400.0 mol/mol, more preferably 300.0 mol/mol. The specified lower and upper interval values are included.

Products and applications

The invention also relates to molded, preferably injection molded, articles containing the polypropylene composition of the present invention. These articles preferably have a flexural modulus, determined according to ISO 178, in the range of 500 to 1000 MPa, more preferably in the range of 550 to 950 MPa, most preferably in the range of 580 to 900 MPa. The articles are equally preferably characterized by a Charpy notched impact strength (NIS), determined in accordance with ISO 179/1eA at 23°C, greater than 20.0 kJ/m ² , more preferably in the range of 25.0 to 95 .0 kJ/m ² , most preferably in the range from 30.0 to 85.0 kJ/m ² . The articles equally preferably also have a Charpy notched impact strength (NIS), determined in accordance with ISO 179/1eA at -20°C, greater than 6.0 kJ/m ² , more preferably in the range of 7.0 up to 75.0 kJ/m ² , most preferably in the range from 7.5 to 70.0 kJ/m ² .

The invention also relates to packaging products or automotive components having a wall thickness of at most 1.5 mm, for example in the range of 0.1 to 1.5 mm, containing the polypropylene composition of the present invention. Such articles include packaging articles such as cups, lids, trays, buckets, and hinged cup containers, as well as automotive components such as door skins, armrests, center consoles, dashboard components, and the like.

The invention also relates to the use of the polypropylene composition according to the invention for the production of packaging articles or automotive components with a wall thickness of at most 1.5 mm in an injection molding process.

Methods and examples

Melt flow index

The Melt Flow Index (MFR) is determined according to ISO 1133 and is reported in g/10 min. The MFR is a measure of the flowability, and hence the processability, of a polymer. The higher the melt flow index, the lower the viscosity of the polymer. MFR ₂ polypropylene homo - and copolymers is determined at a temperature of 230°C and a load of 2.16 kg. The MFR ₁ of polyethylene, as well as elastomeric random copolymers of ethylene and alpha-olefin, is determined at a temperature of 230° C. and a load of 2.16 kg.

Differential Scanning Calorimetry (DSC)

Differential scanning calorimetry (DSC) data, melting point (T _pl ) and enthalpy of fusion (H _pl ), crystallization temperature (T _cr ) and enthalpy of crystallization (H _cr ) are determined using a TA Instrument Q200 differential scanning calorimetry (DSC) instrument on samples 5 to 7 mg. DSC is carried out in accordance with ISO 11357 Part 3 Method C ₂ in a heat/cool/heat cycle at a scan rate of 10°C/min over a temperature range of -30 to +225°C. The crystallization temperature (T _cr ) and the heat of crystallization (H _cr ) are determined in the cooling stage, while the melting point (T _pl ) and the enthalpy of fusion (H _pl ) are determined in the second heating stage.

Xylene Cold Solubles (XCS)

Soluble in cold xylene fraction at room temperature (XCS in % wt.) determined at 25°C in accordance with ISO 16152; 5th edition; 2005-07-01.

Modulus of elasticity in bending

The flexural modulus is determined at 3-point bending at 23° C. according to ISO 178 on 3 test bars 80×10×4 mm ³ , injection molded in accordance with EN ISO 1873-2.

Notched impact strength (NIS)

Charpy notched impact strength (NIS) is measured according to ISO 179 1eA at +23°C or at -20°C using injection molded test rods measuring 80×10×4 mm ³ obtained in accordance with EN ISO 1873-2.

Hexane soluble fraction (C6 FDA)

The amount of hexane extractable polymer according to the FDA method (Federal Registration, Title 21, Chapter 1, Part 177, Section 1520, s. Appendix B) is determined on films produced on a PM30 cast film extrusion line with a melt temperature of approximately 220°C, with L/D ratio 20 and screw diameter 30 mm (feeding zone long 4D, 5.8 mm deep, compression zone long 10D, melting zone long 6D, 2.3 mm deep using a set of sieves 36-400-900-400 mesh/ cm ² ), using a 200 mm diameter head with a head gap of 0.55 to 0.60 mm, screw speed 50 rpm and water temperature of the cooling rollers: both rollers 40°C (heating-cooling unit), air gap 0, 5 mm, air supply by blade blower 1 bar. Film thickness 100 µm.

The amount of hexane-soluble polymer is determined by the FDA method (Federal Registration, Title 21, Chapter 1, Part 177, Section 1520, s. Appendix B) on film samples obtained as described above. The extraction is carried out at a temperature of 50°C and an extraction time of 2 hours.

Crystex Analysis

Method of crystalline and soluble fractions

The crystalline (CF) and soluble (SF) fractions of the polypropylene (PP (PP)) compositions, as well as the comonomer content and intrinsic viscosities of the respective fractions, were analyzed using the CRYSTEX QC method (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 cycles of dissolution at 160°C, crystallization at 40°C and redissolution in 1,2,4-trichlorobenzene (1,2,4-TCB) at 160°C in a TREF column (elution fractionation with increasing temperature, the column is filled with an inert material, such as glass beads), as shown in FIG. 1b (see also Del Hierro, P., Ortin, A., Monrabal, B., Soluble Fraction Analysis in Polypropylene, The Column Advanstar Publications, February 2014, Pages 18-23). RF and CF quantification and ethylene content (C ₂ ) were quantified using an infrared detector (IR4) and a built-in 2-capillary viscometer, which was used to determine intrinsic viscosity (IV).

The IR4 detector is a multi-wavelength detector that detects IR absorption at two different ranges (CH ₃ and CH ₂ ) 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 ranging from 2 to 69% by weight. (determined by ¹³ C-NMR) and at different concentrations between 2 and 13 mg/ml for each EP copolymer used for calibration.

The amount of soluble fraction (SS) and crystalline fraction (CF) are correlated by calibrating the XS with the "cold xylene soluble" (XCS) amount and, respectively, the cold xylene insoluble (XCI) fraction, determined according to the standard gravimetric method according to ISO 16152. Calibration XS is obtained by testing various EP copolymers with an XS content in the range of 2-31% wt.

The intrinsic viscosity (IV) of the original EP copolymer and its soluble and crystalline fraction is determined using an in-line 2-capillary viscometer and correlated with the corresponding IV determined by the standard method in decalin according to ISO 1628. Calibration is carried out using different EP and PP copolymers with IV in the range 2-4 dl/g.

A sample of the PP composition to be analyzed is weighed at concentrations of 10 to 20 mg/mL. After automatically filling the vial with 1,2,4-TCB containing 250 mg/l 2,6-tert-butyl-4-methylphenol (BHT) as an antioxidant, the sample is dissolved at 160°C until complete dissolution is achieved, usually for 60 min, with constant stirring at 800 rpm.

As shown in FIG. 1a and 1b, a certain volume of sample solution is injected 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 the IV [dl/g] and C ₂ [% wt.] for the 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 % C ₂ , IV). In this context, EP (EP) means ethylene-propylene copolymer and PP (PP) means polypropylene.

Intrinsic viscosity (if not determined in the Crystex instrument)

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

Comonomer content (in pure crystalline matrix)

Quantitative infrared (IR) spectroscopy is used to quantify the ethylene content of poly(ethylene-co-propene) copolymers through calibration by a basic method.

Calibration is facilitated by using a set of internal, non-commercial calibration standards of known ethylene content, determined by quantitative ¹³ C nuclear magnetic resonance (NMR) spectroscopy in solution. The calibration procedure is carried out in the usual way, well described in the literature. The calibration set consists of 38 calibration standards with an ethylene content in the range of 0.2-75.0 wt.%, produced either in pilot or full scale under a number of conditions. The calibration set is chosen to reflect the typical variety of copolymers that are encountered in the final quantitative IR spectroscopy method.

Quantitative IR spectra were recorded in the solid state using a Bruker Vertex 70 FT-IR spectrometer. The spectra were recorded on 25×25 mm square films with a thickness of 300 μm obtained by compression molding at 180-210°C and 4-6 MPa. For samples with very high ethylene content (>50 mol %), 100 µm thick films are used. Standard FT-IR transmission spectroscopy with a spectral interval of 5000-500 cm ^-1 , aperture of 6 mm, spectral resolution of 2 cm ^-1 , 16 background scans, 16 spectrum scans, with an interferogram duty factor of 64 and a 3-term Blackman-Harris apodization is used .

The quantitative analysis is carried out using the total area of CH ₂ rolling deformations at 730 and 720 cm ^-1 (A _Q ) corresponding to (CH ₂ ) _>2 structural units (G integration method, boundaries 762 and 694 cm ^-1 ). The quantitative band is normalized to the area of the CH band at 4323 cm ^-1 ( _AR ) corresponding to the CH structural units (integration method G, limits 4650, 4007 cm ^-1 ). The ethylene content in mass percent units is then predicted from the normalized absorbance ( A _Q /A _R ) using a quadratic calibration curve. The calibration curve was built in advance by ordinary least squares (OLS) regression of normalized absorbances and contents of primary comonomers measured on the calibration set.

Poly(propylene-co-ethylene) - ethylene content for calibration using spectroscopy ¹³ C-NMR

Quantitative ¹³ C{ ¹ H} NMR spectra were recorded in solution using a Bruker Avance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for ¹ H and ¹³ C, respectively. All spectra were recorded with ^{a 13°} C. optimized 10 mm extended temperature probe head at 125° C. using nitrogen gas for all pneumatic devices. Approximately 200 mg of the material is dissolved in 3 ml of 1,2-tetrachloroethane- d ₂ (TCE- d ₂ ) together with chromium (III) acetylacetonate (Cr(acac) ₃ ) to give a 65 mM solution of the relaxation agent in a solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogeneous solution, after initial sample preparation in the thermoblock, the NMR tube is further heated in a rotary oven for at least 1 hour. When inserted into a magnet, the tube rotates at 10 Hz. This configuration was chosen primarily because of the high resolution and quantification required to accurately quantify the ethylene content. Standard single-pulse excitation is applied without NOE, using an optimized tip angle, 1 second recovery timeout, and a two-level WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A ., Baugh, D. Winniford, B., 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) transients are recorded per spectrum. Quantitative spectra ¹³ C{ ¹ H} NMR process, integrate and determine the appropriate quantitative indicators from the integrals. All chemical shifts are indirectly assigned to the central methylene group of the ethylene block (EEE) at 30.00 ppm. using solvent chemical shift. This approach allows you to match links even if this structural link is missing. Characteristic signals corresponding to ethylene incorporation are observed (Cheng, HN, Macromolecules 17 (1984), 1950) and the comonomer fraction is calculated as the fraction of ethylene in the polymer relative to all monomers in the polymer: fE=(E/(P+E). Comonomer fraction quantified using the method of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157) by integrating multiple signals over the entire spectral region in the ¹³ C{ ¹ H} spectrum. This method was chosen because its robust character and ability to take into account the presence of regio-defects when necessary Integral regions are slightly adjusted to improve applicability over the range of comonomer contents encountered Mole percent comonomer incorporation is calculated from the mole fraction: E[mol %]=100×fE Mass percent comonomer inclusions are calculated from the mole fraction: E[wt %]=100×(fE×28.06)/((fE×28.06)+((1-fE)×42.08)).

VOC and TLOS (according to VDA278)

VOC

The VOC value is determined according to VDA 278, October 2011, on injection molded plates. VDA 278, October 2011, is an organic emission thermal desorption analysis for the characterization of non-metallic materials for vehicles (VDA Verband der Automobilindustrie). According to VDA 278, October 2011, the value for VOC is defined as "total amount of volatile and medium volatile substances". It is calculated as the equivalent of toluene. The method described in this Directive allows the determination and analysis of substances in the boiling/elution range up to n-pentacosane (C ₂₅ ).

TLOS

The value for TLOS is determined in accordance with VDA 278, October 2011, on injection molded plates. According to VDA 278, October 2011, the value for TLOS is defined as "total low volatility substances" that elute from the retention time of n-tetradecane (inclusive). It is calculated as the equivalent of hexadecane. Determine and analyze substances in the boiling range of n-alkanes from "C ₁₄ " to "C ₃₂ ".

Examples

Catalyst for the first heterophasic propylene copolymer (A)

The metallocene used (MC(MC)) is anti -dimethyl-silandiyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl] [2-methyl - 4-(3,5-dimethylphenyl)-5-methoxy-6- tert- butylinden-1-yl]zirconium dichloride disclosed in EP 19177308.4 as ICS3.

Preparation of the support MAO-silica

The steel reactor, equipped with a mechanical stirrer and filter mesh, was flushed with nitrogen and the temperature of the reactor was set to 20°C. Silica grade DM-L-303 from AGC Si-Tech Co., pre-calcined at 600°C (5.0 kg), is then added from the feed drum, followed by gentle pressurization and depressurization with nitrogen using manual valves. Toluene (22 kg) is then added. The mixture is stirred for 15 minutes. Then a 30% (w/w) solution of MAO in toluene (9.0 kg) from Lanxess was added via the feed line at the top of the reactor over 70 minutes. The reaction mixture is then heated to 90°C and stirred at 90°C for another two hours. The suspensions are allowed to settle and the mother liquor is filtered. The catalyst is washed twice with toluene (22 kg) at 90° C., followed by precipitation and filtration. The reactor is cooled to 60°C and the solid is washed with heptane (22.2 kg). Finally, the MAO-treated SiO ₂ is dried at 60° under nitrogen flow for 2 hours and then for 5 hours under vacuum (-0.5 barg) with stirring. The MAO-treated vehicle is collected as a free-flowing white powder which contains 12.2% wt. Al.

Catalyst preparation

A 30% (w/w) solution of MAO in toluene (0.7 kg) was added through a burette at 20° C. to a steel reactor sealed with nitrogen. Toluene (5.4 kg) is then added with stirring. MC described above (93 g) is added from a metal cylinder, followed by 1 kg of toluene. The mixture is stirred for 60 min at 20°C. Trityl tetrakis(pentafluorophenyl)borate (91 g) was then added from a metal cylinder, followed by 1 kg of toluene. The mixture is stirred for 1 hour at room temperature. The resulting solution was added to the stirred filter cake of the MAO-(silica) carrier prepared as described above over 1 hour. The filter cake is left to stand for 12 hours, after which it is dried in a stream of N ₂ at 60° C. for 2 hours and another 5 hours under vacuum (-0.5 barg) with stirring. A sample of the dried catalyst was taken as a pink free flowing powder containing 13.9% Al and 0.11% Zr.

Catalyst for the second heterophasic propylene copolymer (C)

To prepare the catalyst, 3.4 liters of 2-ethylhexanol and 810 ml of propylene glycol butyl monoether (4:1 molar ratio) are added to a 20.0 liter reactor to a well stirred alcohol mixture. Then slowly add 7.8 l of a 20.0% solution of butylethylmagnesium (BEM) in toluene supplied by Crompton GmbH. While adding the temperature is maintained at 10.0°C. After the addition, the temperature of the reaction mixture was raised to 60.0° C. and stirring was continued at this temperature for another 30 minutes. Finally, after cooling to room temperature, the obtained Mg-alkoxide is transferred to a storage vessel.

21.2 g of the Mg-alkoxide prepared above are mixed with 4.0 ml of bis(2-ethylhexyl)citraconate for 5 minutes. After mixing, the resulting Mg complex is used immediately to prepare a catalyst component.

Place 19.5 ml of titanium tetrachloride in a 300 ml reactor equipped with a mechanical stirrer at 25.0°C. The stirring speed is adjusted to 170 rpm. 26.0 g of the Mg complex prepared above is added over 30 minutes while maintaining the temperature at 25.0°C. 3.0 ml of Viscoplex® 1-254 and 1.0 ml of a toluene solution of 2 mg Necadd 447 ^TM are added. Then 24.0 ml of heptane are added to form an emulsion. Stirring is continued for 30 minutes at 25.0°C, after which the reactor temperature is raised to 90.0°C over 30 minutes. The reaction mixture is stirred for another 30 min at 90.0°C. After that, the stirring is stopped and the reaction mixture is allowed to stand for 15 min at 90.0°C. The solid material is washed 5 times: washings are performed at 80.0° C. with stirring for 30 minutes at 170 rpm. After stopping the stirring, the reaction mixture is allowed to stand for 20-30 min and then drained with a siphon.

Wash 1: wash is carried out with a mixture of 100 ml of toluene and 1 ml of donor.

Wash 2: Wash is carried out with a mixture of 30 ml TiCl ₄ and 1 ml donor.

Wash 3: wash is carried out with 100 ml of toluene.

Wash 4: wash is carried out with 60 ml of heptane.

Wash 5: Wash with 60 ml of heptane with stirring for 10 minutes.

Thereafter, stirring was stopped and the reaction mixture was allowed to stand for 10 minutes while lowering the temperature to 70° C., then siphoned off and then N ₂ was sparged for 20 minutes to give an air-sensitive powder.

Polymerization

To obtain the claimed and comparative examples, four heterophasic propylene copolymers are polymerized in a Borstar PP type pilot plant with a prepolymerization reactor, a liquid phase loop reactor (Loop) and three gas phase reactors (GPR1, GPR2 and GPR3). The PP-A1 and PP-A2 copolymers have a composition according to the description of the first heterophasic propylene copolymer (A) and are based on the single site catalyst system discussed above. The PP-C1 and PP-C2 copolymers have a composition according to the description of the second heterophasic propylene copolymer (C) and are based on the Ziegler-Natta catalyst system discussed above. In the case of the latter system, dicyclopentyldimethoxysilane (donor D) is used as an external electron donor and triethylaluminum as a cocatalyst. The respective ratios, as well as other polymerization conditions, are shown in Table 1 below.

Table 1 . Polymerization conditions and properties of copolymers

PP-A1 RR-A2 PP-C1 RR-C2 Catalyst BCC BCC CCN CCN Donor - - D D Prepolymerization Co/ED mol/mol 0 0 7.3 40 Co/Ti mol/mol 0 0 220 230 Temperature °C 25 20 thirty thirty Time of stay min 20 20 5 5 Loop Temperature °C 70 70 75 72 Separation % wt. 49 57 thirty thirty _H2 / _C3 mol/kmol 0.40 0.45 14.8 18.8 PTR g/10 min 60 109 55 110 GPR1 Temperature °C 70 80 80 80 Separation % wt. 33 34 35 35 _H2 / _C3 mol/kmol 3.7 4.0 149.7 136.8 _C2 / _C3 mol/kmol 0.0 0.0 0.0 0.0 PTR g/10 min 102 109 55 80 PTR(GPR1) g/10 min 228 109 55 62 XCS % wt. 1.0 1.0 2.0 2.0 _C2 % wt. 0.0 0.0 0.0 0.0 GPR2 Temperature °C 70 75 70 70 _C2 / _C3 mol/kmol 807 854 584.6 514.9 _H2 / _C2 mol/kmol 2.3 1.9 116.5 119.0 Separation % wt. 18 9 20 17 _C2 % wt. 4.1 1.9 8.5 7.9 PTR g/10 min 43 90 eleven 15 GPR3 Temperature °C - - 85 85 _C2 / _C3 mol/kmol - - 585.2 1429 _H2 / _C2 mol/kmol - - 92.7 285.6 Separation % wt. 0 0 15 18 _C2 % wt. - - 13 18.9 PTR g/10 min - - eleven 18 Granule XCS % wt. 17.5 11.6 32.9 31.5 _C2 (XCS) % wt. 18.5 24.1 34.3 44.8 XB(XCS) dl/g 2.4 2.5 3.6 2.3 PTR g/10 min 43 90 eleven 18 XB ratio - 1.0 1.0 1.0 1.2 T _pl °C 154 154 165 165 T _cr °C 114 114 116 115 Crystex SF % wt. 18.1 10.6 31.3 n.i. _C2 % wt. 4.09 1.9 15.1 n.i. C ₂ (RF) % wt. 17.6 23.3 38.6 n.i. C ₂ (CF) % wt. 1.38 0 5.1 n.i. XV dl/g 1.43 1.22 2.1 n.i. XV(RF) dl/g 2.68 2.38 3.6 n.i. HV(CF) dl/g 1.13 1.07 1.5 n.i.

N.i. - not measured; BCC (SSC) - single-center catalyst; KCN (ZNC) - Ziegler-Natta catalyst

Mixing the composition in the melt

Inventive compositions IE1 to IE4 and comparative compositions CE1 to CE3 are prepared from the copolymers described above in combination with a commercial ethylene-octene plastomer corresponding to the ethylene-alpha-olefin (B) elastomeric random copolymer of the present invention. Said copolymer (B) is an Engage 8842 plastomer from DOW Chemical (USA) having a 1-octene content of 45 wt %, a density of ₈₅₇ kg/ ^m °C and a load of 2.16 kg) 1.0 g/10 min and an intrinsic viscosity (as determined according to DIN ISO 1628/1 in decalin at 135°C) 2.60 dl/g.

The melt mixing step is carried out in a Coperion ZSK57 twin screw extruder with an L/D ratio of 45:1 and a diameter D of 57 mm using a temperature setting in the range from 200 to 240°C. With stirring in the melt add 0.2% of the mass. Irganox B225 (1:1 blend of Irganox 1010 (pentaerythrityl-tetrakis(3-(3',5'-di-tert-butyl-4-hydroxytoluyl)propionate and tris(2,4-di-tert-butylphenyl)phosphate)phosphite) ) from BASF AG, Germany) as stabilizers and 0.05% wt. calcium stearate as an acid scavenger. The corresponding compositions, as well as the properties of the claimed compositions IE1-IE4 and comparative compositions CE1-CE3 are shown in table 2.

Table 2 . Compositions and properties

IE1 IE2 IE3 IE4 CE1 CE2 CE3 PP-A1 % wt. 85 75 65 100 PP-A2 % wt. 75 100 Plastomer B % wt. 15 15 25 25 PP-C1 % wt. 10 10 PP-C2 % wt. 100 PTR2 g/10 min 28 25 19 36 43 18 88 XCS % wt. 29.8 31.4 39.7 33.7 17.5 31.5 11.6 _C2 (XCS) % wt. 25.5 27.1 31.7 34.3 18.5 44.8 24.1 XB(XCS) dl/g 2.5 2.6 2.6 2.5 2.4 2.3 2.5 Modulus of elasticity in bending MPa 759 799 636 770 934 773 1138 NIS Charpy, 23°C kJ/m² 61.4 64.8 74.9 34.1 8.1 35.9 4.41 NIS Charpy, -20°C kJ/m² 8.39 10.06 65.3 7.95 2.73 8.50 1.82 VOC µg/g 32 49 47 36 n.i. 196 n.i. TLOS µg/g 78 100 108 79 n.i. 367 n.i.

The claimed compositions not only outperform the comparative compositions of the PP-A1, PP-A2 and PP-C2 copolymers, respectively, in terms of the balance of mechanical properties, while having a significantly higher MFR ₂ for the production of thin-walled parts, but also these compositions show lower emissions than PP- C2 as required.

Claims (29)

1. Polypropylene composition for producing packaging products or automotive components, containing: from 60 to 95 wt.% of the first heterophasic propylene copolymer (A), containing - from 78.0 to 92.0 wt.% of the crystalline matrix (A1), which is a homo- or copolymer of propylene, and the specified crystalline matrix corresponds to the crystalline fraction (CF) determined in accordance with the CRYSTEX QC method of ISO 6427-B, and contains from 0.0 to 2.0 wt.% comonomer, and - from 8.0 to 22.0 wt.% of an amorphous propylene-ethylene elastomer (A2), optionally containing C ₄ -C ₁₂ alpha-olefin(s) as additional comonomers, dispersed in said crystalline matrix (A1), - where (A1) and (A2) add up to 100 wt.%, and where the specified amorphous propylene-ethylene elastomer (A2) corresponds to the soluble fraction (RF), determined in accordance with the CRYSTEX QC method of ISO 6427-B, and contains from 15.0 to 30.0 wt.% comonomer, said heterophasic propylene copolymer has a melt flow index MFR ₂ determined in accordance with ISO1133 at 230°C and a load of 2.16 kg, from 30 to 120 g/10 min, and from 5 to 40 wt.% elastomeric random copolymer of ethylene and alpha-olefin (B), characterized by MFI ₂ determined in accordance with ISO1133 at 190°C and a load of 2.16 kg, from 0.1 to 100 g/10 min and density in the range from 840 to below 900 kg/m ³ , where (A) and (B) add up to 100% by weight. 2. Polypropylene composition according to claim 1, also containing from 5.0 to 15.0 wt.% of the second heterophasic propylene copolymer (C), characterized by an index of melt flow MFR ₂ determined in accordance with ISO1133 at 230°C and a load of 2 .16 kg, from 5 to 25 g/10 min, and containing a cold xylene-soluble fraction (XCS) in the range from 25.0 to 50.0 wt.%. 3. Polypropylene composition according to claim 1, additionally containing from 5.0 to 30.0 wt.% of a reinforcing mineral filler (D). 4. Polypropylene composition according to claim 1, having a melt flow index MFR ₂ determined in accordance with ISO1133 at 230°C and a load of 2.16 kg, from 10.0 to 100 g/10 min, and containing soluble in cold xylene fraction (XCS) in the range from 20.0 to 50.0 wt.%, and the specified fraction has a content of comonomers selected from ethylene and/or C ₄ -C ₁₂ -alpha-olefin(s), in the range from 20.0 up to 40.0 wt.%. 5. Polypropylene composition according to claim 1, characterized by less than 100 µg/g of volatile compounds (VOC, VDA 278, October 2011) and less than 200 µg/g of low-volatility organic condensables (TLOC, VDA 278, October 2011). 6. Polypropylene composition according to claim 1, characterized in that the first heterophasic propylene copolymer (A) contains: - (A1) from 79.0 to 91.0 wt.%, preferably from 80.0 to 90.0 wt.% of the crystal matrix corresponding to the crystal fraction (CF) determined in accordance with the CRYSTEX QC method of ISO 6427-B , wherein said crystalline fraction (CF) contains from 0.5 to 1.8 wt.%, preferably 0.7 to 1.6 wt.% ethylene and has an intrinsic viscosity (IV), determined in accordance with ISO1628, from 0 .6 to 2.0 dl/g, preferably 0.8 to 1.8 dl/g, and - (A2) from 9.0 to 21.0 wt.%, preferably from 10.0 to 20.0 wt.% of an amorphous propylene-ethylene elastomer dispersed in said crystalline matrix (A1), said propylene-ethylene copolymer corresponding to soluble fraction (SF), determined in accordance with the CRYSTEX QC method of ISO 6427-B, contains from 16.5 to 28.0 wt.%, preferably from 17.5 to 26.0 wt.% ethylene, and has an intrinsic viscosity (IV), determined in accordance with ISO1628, from 1.8 to 3.5 dl/g, preferably from 2.0 to 3.2 dl/g, where (A1) and (A2) add up to 100% by weight. 7. Polypropylene composition according to claim 1, characterized in that the first heterophasic propylene copolymer (A) has a melt flow index MFR ₂ determined in accordance with ISO1133 at 230°C and a load of 2.16 kg, from 35 to 110 g/ 10 min and/or a hexane-soluble fraction according to the FDA method (C6FDA) in the range from 0.8 to 2.8 wt.%, preferably in the range from 1.0 to 2.3 wt.%. 8. Polypropylene composition according to claim 1, characterized in that the elastomeric random copolymer of ethylene and alpha-olefin (B) is based on a solution polymerization method using a single-site catalyst and has a melt flow index MFR ₂ determined in accordance with ISO1133 at 190 °C and a load of 2.16 kg, from 0.2 to 50 g/10 min and a density in the range from 850 to below 890 kg/m ³ . 9. Polypropylene composition according to claim 3, characterized in that the reinforcing mineral filler is selected from talc, mica, wollastonite and calcium carbonate, having a median particle size (D ₅₀ ) of 0.5-15 μm and an upper fraction (D ₉₅ ) 1- 50 µm. 10. A method for the production of a polypropylene composition according to any one of paragraphs. 1-9, including the following technological stages: (i) polymerizing the first heterophasic propylene copolymer (A) in a sequential polymerization process in the presence of a single site catalyst system, and (ii) melt blending said copolymer (A) with a suitable amount of an elastomeric random copolymer of ethylene and alpha-olefin (B), (iii) optionally adding a suitable amount of a second heterophasic propylene copolymer (C) polymerized in the presence of a Ziegler-Natta type catalyst system, as well as a suitable amount of reinforcing mineral filler (D) in said melt blending step, followed by (iv) solidifying the resulting melt in a strand granulation or underwater granulation step. 11. The process of claim 10 wherein the single site catalyst system for polymerizing the first heterophasic propylene copolymer (A) comprises an asymmetric metallocene catalyst complex and one or more cocatalysts. 12. The process of claim 10, wherein the Ziegler-Natta type catalyst system for polymerizing the second heterophasic propylene copolymer (C) comprises a self-supporting Ziegler-Natta catalyst containing a magnesium compound, a titanium compound, and a non-phthalic internal electron donor (ID), a cocatalyst that is an aluminum compound, and an external donor (ED), which is a silane. 13. The product obtained by injection molding containing a polypropylene composition according to any one of paragraphs. 1-9, characterized by a modulus of elasticity in bending, determined in accordance with ISO 178, in the range from 500 to 1000 MPa, Charpy notched impact strength (NIS), determined in accordance with ISO 179/1eA at 23°C, in the range from 25.0 to 95.0 kJ/m ² , and NIS Charpy, determined in accordance with ISO 179/1eA at -20°C, in the range from 7.0 to 75.0 kJ/m ² . 14. A packaging product or automotive component containing a polypropylene composition according to any one of paragraphs. 1-9 and having a wall thickness of at most 1.5 mm. 15. The use of a polypropylene composition according to any one of paragraphs. 1-9 for the production of a packaging product or automotive component containing a polypropylene composition according to any one of paragraphs. 1-7 and having a wall thickness of at most 1.5 mm in an injection molding process.

Images