WO2022088019A1

WO2022088019A1 - Glass fiber-reinforced composition with improved impact strength

Info

Publication number: WO2022088019A1
Application number: PCT/CN2020/125175
Authority: WO
Inventors: Shengquan ZHU
Original assignee: Borouge Compounding Shanghai Co., Ltd.
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2022-05-05

Abstract

A polyolefin composition (PC) comprising: a) from 55.0 to 73.0 wt. -%, of a heterophasic propylene-ethylene copolymer (HECO), consisting of i) a crystalline propylene homopolymer matrix (M) having an MFR ₂ of less than 80g/10min.; ii) an elastomeric propylene-ethylene copolymer (EC); b) from 26.0 to 44.0 wt. -%, of glass fibers (GF); c) from 0.5 to 5.0 wt. -%, of polar-modified polypropylene (PMP); and d) from 0.1 to 5.0 wt. -%,, of at least one additive (A), wherein the HECO has each of the following properties: i) an MFR ₂ in the range from 5.0 to 30.0 g/10 min; ii) an XCS content in the range from 30.0 to 45.0 wt. -%; and iii) a C2 (XCS) in the range from 30.0 to 45.0 wt. -%.

Description

GLASS FIBER-REINFORCED COMPOSITION WITH IMPROVED IMPACT STRENGTH

The present invention relates to a polyolefin composition comprising a heterophasic propylene-ethylene copolymer, glass fibers, a polar-modified polypropylene and additives, as well as articles comprising said composition.

Polypropylene is a material used in a wide variety of technical fields, and reinforced polypropylenes have in particular gained relevance in fields previously exclusively relying on non-polymeric materials, in particular metals. One particular example of reinforced polypropylenes are glass fiber reinforced polypropylenes. Such materials enable a tailoring of the properties of the composition by selecting the type of polypropylene, the amount of glass fiber and sometimes by selecting the type of coupling agent used.

Accordingly, nowadays glass-fiber reinforced polypropylene is a well-established material for applications requiring good mechanical properties such as high stiffness and thermal stability, for example in safety articles designed to protect the user/wearer in the case of accidents.

The requirements for materials to be used in such articles is often extremely stringent, for straightforward safety reasons. For example, if a polypropylene is to be used in a baby safety seat (for use in vehicles for example) , then not only a high stiffness (flexural modulus) of 5000 MPa is required, but also a notched impact strength of at least 25 kJ/m ². Likewise, safety helmets (for use on construction sites, for example) require a flexural modulus of 5500 MPa and a notched impact strength of at least 25 kJ/m ².

Typical glass fiber-reinforced compositions, which are based on propylene homopolymers, do not have sufficient impact strength for these highly demanding applications. Whilst it is well understood in the art that impact modifiers, such as ethylene-alpha olefin copolymers, used in amounts of 10 to 20 wt. -%can be used to improve the impact strength, this approach has its limitations and furthermore has a detrimental effect on the stiffness, as well as on the heat deflection temperature (a key property when considering the processability and application of such compositions) .

Consequently, a new polypropylene composition having improved impact strength without degrading the stiffness too severely, whilst being suitable for use in baby vehicle safety seats and safety helmets is required.

Therefore, the present invention is directed to a polyolefin composition (PC) comprising:

a) from 55.0 to 73.0 wt. -%, based on the total weight of the composition, of a heterophasic propylene-ethylene copolymer (HECO) , consisting of:

i) a crystalline propylene homopolymer matrix (M) having a MFR ₂ of less than 80g/10min.;

ii) an elastomeric propylene-ethylene copolymer (EC) ;

b) from 26.0 to 44.0 wt. -%, based on the total weight of the composition, of glass fibers (GF) ;

c) from 0.5 to 5.0 wt. -%, based on the total weight of the composition, of polar modified polypropylene (PMP) ; and

d) from 0.1 to 5.0 wt. -%, based on the total weight of the composition, of at least one additive (A) other than the glass fibers (GF) and the polar modified polypropylene (PMP) ,

wherein the HECO has each of the following properties:

i) a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min;

ii) a xylene cold solubles (XCS) content in the range from 30.0 to 45.0 wt. -%; and

iii) an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 30.0 to 45.0 wt. -%,

wherein the polyolefin composition (PC) is free of elastomeric ethylene copolymers, free of fillers other than the glass fibers (GF) , and free of propylene homopolymers other than the crystalline propylene homopolymer matrix (M) and any carrier polymers present in an additive masterbatch within the scope of component d) .

In another aspect, the present invention is directed to a polyolefin composition (PC) consisting of:

i) a crystalline propylene homopolymer matrix (M) having a MFR ₂ of less than 80g/10min;

ii) an elastomeric propylene-ethylene copolymer (EC) ;

wherein the HECO has each of the following properties:

iii) an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 30.0 to 45.0 wt. -%.

In a preferred embodiment, the heterophasic propylene-ethylene copolymer (HECO) has one or more, preferably all, of the following properties:

i) a total ethylene (C2) content in the range from 9.0 to 20.0 wt. -%, preferably in the range from 11.0 to 17.0 wt. -%, most preferably in the range from 12.0 to 14.0 wt. -%; and

ii) an intrinsic viscosity of the xylene cold soluble fraction (IV (XCS) ) in the range from 1.8 to 3.2 dl/g, preferably in the range from 2.1 to 2.9 dl/g, most preferably in the range from 2.3 to 2.7 dl/g.

In another preferred embodiment, the heterophasic propylene-ethylene copolymer (HECO) has one or more, preferably all, of the following properties:

i) a flexural modulus, measured according to according to ISO 178 on 80x10x4 mm ³ test bars injection molded in line with EN ISO 1873-2, in the range from 700 to 2000 MPa, more preferably in the range from 800 to 1500 MPa, most preferably in the range from 900 to 1200 MPa;

ii) a Charpy notched impact strength, measured at +23 ℃ according to ISO 179-1 1eA using injection-molded bar test specimens of 80x10x4 mm ³ prepared in accordance with ISO 1873-2: 2007, in the range from 20.0 to 100.0 kJ/m ², more preferably in the range from 40.0 to 80.0 kJ/m ², most preferably in the range from 50.0 to 70.0 kJ/m ²; and

iii) a Charpy notched impact strength, measured at -20 ℃ according to ISO 179-1 1eA using injection-molded bar test specimens of 80x10x4 mm ³ prepared in accordance with ISO 1873-2: 2007, in the range from 5.0 to 30.0 kJ/m ², more preferably in the range from 7.0 to 20.0 kJ/m ², most preferably in the range from 9.0 to 15.0 kJ/m ².

In another preferred embodiment, the crystalline propylene homopolymer matrix (M) of the heterophasic propylene-ethylene copolymer (HECO) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 30.0 to 79.0 g/10 min.

In another preferred embodiment, the heterophasic propylene-ethylene copolymer (HECO) has an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 31.0 to 39.0 wt%.

In another preferred embodiment, heterophasic propylene-ethylene copolymer (HECO) comprises a polymeric nucleating agent, preferably a vinyl cycloalkane polymer, more preferably a vinyl cyclohexane polymer, most preferably a vinyl cyclohexane homopolymer.

In another preferred embodiment, the glass fibers (GF) are chopped glass fibers, more preferably chopped glass fibers with a nominal diameter in the range from 5 to 30 μm, preferably in the range from 7 to 20 μm, most preferably in the range from 10 to 15 μm, and/or a chop length in the range from 1.0 to 10.0 mm, more preferably in the range from 2.0 to 7.0 mm, most preferably in the range from 3.0 to 5.0 mm.

In another preferred embodiment, the polar-modified polypropylene (PMP) has a polar group loading in the range from 0.5 to 3.0 wt. -%.

In another preferred embodiment, the polyolefin composition (PC) has a flexural modulus of at least 4500 MPa, and/or a Charpy notched impact strength of at least 25.0 kJ/m ².

In another preferred embodiment, the polyolefin composition (PC) has a heat deflection temperature, measured according to ISO 75-2 under a load of 1.8 MPa, in the range from 130 to 160 ℃.

In another preferred embodiment, the polyolefin composition (PC) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min.

In a further aspect, the present invention is directed to an article comprising more than 75 wt. -%of the polyolefin composition (C) , preferably a molded article, most preferably an injection molded article.

In a preferred embodiment, the article is a safety article, more preferably a baby vehicle safety seat or safety helmet.

The present invention will now be described in more detail.

The heterophasic propylene-ethylene copolymer (HECO)

The main component of the polyolefin composition is the heterophasic propylene-ethylene copolymer (HECO) .

A heterophasic propylene copolymer (HECO) comprises at least two distinct phases, namely a propylene homopolymer crystalline matrix phase (M) and an elastomeric propylene-ethylene copolymer (EC) . The combination of these two very different phases creates a composition with a beneficial balance of mechanical properties, as given by the stiffness and impact strength.

It is especially preferred that both the crystalline matrix (M) and elastomeric propylene-ethylene copolymer (EC) of the heterophasic propylene copolymer (HECO) of the present invention are bimodal.

The heterophasic propylene-ethylene copolymer (HECO) of the present invention has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min, preferably in the range from 6.0 to 25.0 g/10 min, more preferably in the range from 7.0 to 20.0 g/10 min, yet more preferably in the range from 8.0 to 15.0 g/10 min, most preferably in the range from 9.0 to 13.0 g/10 min.

The heterophasic propylene-ethylene copolymer (HECO) of the present invention has a xylene cold solubles (XCS) content in the range from 30.0 to 45.0 wt. -%, preferably in the range from 30.0 to 40.0 wt. -%, most preferably in the range from 31.0 to 35.0 wt. -%.

It is preferred that the heterophasic propylene-ethylene copolymer (HECO) of the present invention has an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 30.0 to 45.0 wt. -%, preferably in the range from 31.0 to 42.0 wt. -%, more preferably in the range from 31.0 to 39.0 wt%, yet more preferably in the range from 33.0 to 39.0 wt. -%, most preferably in the range from 36.0 to 39.0 wt. -%.

It is preferred that the heterophasic propylene-ethylene copolymer (HECO) of the present invention has a total ethylene (C2) content in the range from 9.0 to 20.0 wt. -%, preferably in the range from 11.0 to 17.0 wt. -%, most preferably in the range from 12.0 to 14.0 wt. -%, as determined by quantitative ¹³C-NMR spectroscopy.

It is preferred that the heterophasic propylene-ethylene copolymer (HECO) of the present invention has an intrinsic viscosity of the xylene cold soluble fraction (IV (XCS) ) in the range from 1.8 to 3.2 dl/g, preferably in the range from 2.1 to 2.9 dl/g, most preferably in the range from 2.3 to 2.7 dl/g.

It is preferred that the crystalline propylene homopolymer matrix (M) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230℃ and 2.16 kg of less than 80.0 g/10 min, more preferably in the range from 30.0 to 79.0 g/10 min, yet more preferably in the range from 40.0 to 70.0 g/10 min, most preferably in the range from 50.0 to 60.0 g/10 min.

It is preferred that the heterophasic propylene-ethylene copolymer (HECO) of the present invention has a flexural modulus measured according to ISO 178 in the range from 700 to 2000 MPa, more preferably from 800 to 1500 MPa, yet more preferably from 900 to 1200 MPa.

It is preferred that the heterophasic propylene-ethylene copolymer (HECO) of the present invention has a Charpy Notched Impact Strength measured according to ISO 179/1eA at +23 ℃ in the range from 20.0 to 100.0 kJ/m ², more preferably from 40.0 to 80.0 kJ/m ², most preferably from 50.0 to 70.0 kJ/m ².

It is preferred that the heterophasic propylene-ethylene copolymer (HECO) of the present invention has a Charpy Notched Impact Strength measured according to ISO 179/1eA at -20 ℃ in the range from 3.0 to 30.0 kJ/m ², more preferably in the range from 5.0 to 30.0 kJ/m ², yet more preferably from 7.0 to 20.0 kJ/m ², most preferably from 9.0 to 15.0 kJ/m ².

The heterophasic propylene-ethylene copolymer (HECO) of the present invention may either be synthesized or selected from commercially available polypropylenes.

The heterophasic propylene-ethylene copolymer (HECO) preferably comprises a polymeric nucleating agent.

A preferred example of such a polymeric nucleating agent is a vinyl polymer, such as a vinyl polymer derived from monomers of the formula

CH ₂ = CH-CHR ¹R ²

wherein R ¹ and R ², together with the carbon atom they are attached to, form an optionally substituted saturated or unsaturated or aromatic ring or a fused ring system, wherein the ring or fused ring moiety contains four to 20 carbon atoms, preferably 5 to 12 membered saturated or unsaturated or aromatic ring or a fused ring system or independently represent a linear or branched C4-C30 alkane, C4-C20 cycloalkane or C4-C20 aromatic ring. Preferably R ¹ and R ², together with the C-atom wherein they are attached to, form a five-or six-membered saturated or unsaturated or aromatic ring or independently represent a lower alkyl group comprising from 1 to 4 carbon atoms. Preferred vinyl compounds for the preparation of a polymeric nucleating agent to be used in accordance with the present invention are in particular vinyl cycloalkanes, in particular vinyl cyclohexane (VCH) , vinyl cyclopentane, and vinyl-2-methyl cyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene or mixtures thereof. It is particularly preferred that the vinyl polymer is a vinyl cycloalkane polymer, preferably selected from vinyl cyclohexane (VCH) , vinyl cyclopentane and vinyl-2-methyl cyclohexane, with vinyl cyclohexane polymer being a particularly preferred embodiment.

It is further preferred that the vinyl polymer of the polymeric nucleating agent is a homopolymer, most preferably a vinyl cyclohexane homopolymer.

The glass fibers (GF)

Another essential component of the polyolefin composition (PC) is the glass fibers (GF) .

The glass fibers are preferably provided in the form of chopped glass fibers.

It is preferred that the chopped glass fibers have a nominal diameter in the range from 5 to 30 μm, preferably in the range from 7 to 20 μm, most preferably in the range from 10 to 15 μm.

It is also preferred that the chopped glass fibers have a chop length in the range from 1.0 to 10.0 mm, more preferably in the range from 2.0 to 7.0 mm, most preferably in the range from 3.0 to 5.0 mm.

The additives (A)

The polyolefin composition (PC) of the present invention may contain additives (A) in an amount of from 0.1 to 5.0 wt. -%. The skilled practitioner would be able to select suitable additives that are well known in the art.

The additives (A) are preferably selected from pigments, antioxidants, UV-stabilisers, anti-scratch agents, mold release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof.

It is understood that the content of additives (A) , given with respect to the total weight of the polyolefin composition (PC) , includes any carrier polymers used to introduce the additives to said polyolefin composition (PC) , i.e. carrier polymers in an additive masterbatch. An example of such a carrier polymer would be a polypropylene homopolymer in the form of powder.

The polar-modified polypropylene (PMP)

In certain preferred embodiments, the polyolefin composition (PC) of the invention may further comprise a polar-modified polypropylene (PMP) .

Whilst not wishing to be bound by any theory, it is believed that the polar-modified polypropylene (PMP) is used as a compatibilizer in the composition, which further helps to disperse the glass fibers within the polyolefin composition (PC) .

It is preferred that the polar-modified polypropylene (PMP) has a content of polar groups content in the range from 0.5 to 3.0 wt. -%, more preferably in the range from 0.8 to 2.0 wt. -%, most preferably in the range from 1.0 to 1.5 wt. -%.

It is also preferred that the polar-modified polypropylene (PMP) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 190℃ and 2.16 kg in the range from 50.0 to 200.0 g/10 min, more preferably in the range from 60.0 to 170.0 g/10 min, yet more preferably in the range from 70.0 to 140.0 g/10 min, most preferably in the range from 80.0 to 120.0 g/10 min.

It is especially preferred that the polar-modified polypropylene (PMP) is a maleic anhydride-modified polypropylene, most preferably a maleic anhydride-modified propylene-ethylene copolymer.

Suitable commercially available polar-modified polypropylenes include SCONA TPPP 8112 GA, available from Byk-Cera (Germany) .

The polyolefin composition

The polyolefin composition of the present invention consists of the heterophasic propylene-ethylene copolymer (HECO) , the glass fibers (GF) , the polar-modified polypropylene (PMP) and at least one additive (A) other than the glass fibers (GF) and the polar-modified polypropylene (PMP) .

Accordingly, the polyolefin composition (PC) comprises:

a) from 55.0 to 73.0 wt. -%, based on the total weight of the composition, of the heterophasic propylene-ethylene copolymer (HECO) ;

c) from 0.5 to 5.0 wt. -%, based on the total weight of the composition, of polar-modified polypropylene (PMP) ;

d) from 0.1 to 5.0 wt. -%, based on the total weight of the composition, of at least one additive (A) other than the glass fibers (F) and polar-modified polypropylene (PMP) ,

In the context of the present invention, an ethylene copolymer is a copolymer having an ethylene content of at least 50 wt. -%. Elastomeric ethylene copolymers, wherein elastomeric is defined as having a low glass transition temperature (T _g) , typically below -20 ℃, are often used in the polymer industry as impact modifiers. The person skilled in the art would understand that an elastomeric ethylene copolymer is different from the elastomeric propylene-ethylene copolymer, which must by definition contain at least 50 wt. -%propylene monomers.

Furthermore, in the context of the present invention, fillers are understood to be particles that are added to polyolefin compositions in order to improve certain properties (often stiffness) , make the product cheaper, or a mixture of both. Typical fillers include mineral fillers such as talc and calcium carbonate, glass fibers, glass bubbles, carbon fibers, carbon nanotubes, and carbon black. Many materials used as fillers can also be used as additives in the context of the present invention (for example talc may function as a nucleating agent, whilst carbon black may function as a pigment) . Whilst the present composition is understood to be free from fillers other than glass fibers, this does not exclude the use of these particulate additives in amounts of less than 2.0 wt. -%, said amounts being understood by the skilled person to fall under the definition of additives, rather than fillers.

Alternatively, the polyolefin composition (PC) consists of:

d) from 0.1 to 5.0 wt. -%, based on the total weight of the composition, of at least one additive (A) other than the glass fibers (F) and polar-modified polypropylene (PMP) .

The polypropylene (PP) is present in the polyolefin composition in an amount of from 55.0 to 73.0 wt. -%, based on the total weight of the composition, more preferably in an amount of from 56.0 to 70.0 wt. -%, yet more preferably in an amount of from 56.0 to 68.0 wt. -%, based on the total weight of the composition.

The glass fibers (GF) are present in the polyolefin composition in an amount of from 26.0 to 44.0 wt. -%, based on the total weight of the composition, more preferably in an amount of from 26.0 to 40.0 wt. -%, most preferably in an amount of from 29.0 to 40.0 wt. -%based on the total weight of the composition.

The polar-modified polypropylene (PMP) is present in the polyolefin composition in an amount of from 0.5 to 5.0 wt. -%, based on the total weight of the composition, more preferably in an amount of from 0.7 to 3.0 wt. -%, yet more preferably in an amount of from 0.9 to 2.0 wt. -%most preferably in an amount of from 1.0 to 1.5 wt. -%based on the total weight of the composition.

Accordingly, in one preferred embodiment, the polyolefin composition (PC) consists of:

a) from 56.0 to 70.0 wt. -%, based on the total weight of the composition, of the heterophasic propylene-ethylene copolymer (HECO) ;

b) from 26.0 to 40.0 wt. -%, based on the total weight of the composition, of glass fibers (GF) ;

c) from 0.7 to 3.0 wt. -%, based on the total weight of the composition, of polar-modified polypropylene (PMP) ;

Accordingly, in a further preferred embodiment, the polyolefin composition (PC) consists of:

a) from 56.0 to 68.0 wt. -%, based on the total weight of the composition, of the heterophasic propylene-ethylene copolymer (HECO) ;

b) from 29.0 to 40.0 wt. -%, based on the total weight of the composition, of glass fibers (GF) ;

c) from 0.9 to 2.0 wt. -%, based on the total weight of the composition, of polar-modified polypropylene (PMP) ;

It is preferred that the polyolefin composition (PC) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min, more preferably in the range from 5.0 to 20.0 g/10 min, most preferably in the range from 5.0 to 10.0 g/10 min.

In order to be suitable for use in safety articles, such as baby vehicle safety seats and safety helmets, the polyolefin composition (PC) according to the present invention requires a beneficial balance of mechanical properties, such as stiffness and impact strength.

Accordingly, it is preferred that the polyolefin composition (PC) has a flexural modulus measured according to ISO 178 of at least 4500 MPa, more preferably of at least 5000 MPa.

The flexural modulus will not typically exceed 9000 MPa.

It is also preferred that the polyolefin composition (PC) has a Charpy notched impact strength measured according to ISO 179/1eA at +23 ℃ of at least 25.0 kJ/m ², more preferably of at least 28.0 kJ/m ².

The Charpy notched impact strength will not typically exceed 50.0 kJ/m ².

Furthermore, it is preferred that the polyolefin composition (PC) has a heat deflection temperature, measured according to ISO 75-2 under a load of 1.8 MPa, in the range from 130 to 160 ℃, more preferably in the range from 135 to 150 ℃, most preferably in the range from 138 to 145 ℃.

Preparation process for the heterophasic propylene-ethylene copolymer (HECO)

The heterophasic propylene-ethylene copolymer (HECO) comprised in the composition according to this invention is preferably produced in a sequential polymerization process in the presence of a Ziegler-Natta catalyst, more preferably in the presence of a catalyst (system) as defined below.

Preferably the heterophasic propylene-ethylene copolymer (HECO) is reactor made, preferably has been produced in a sequential polymerization process, wherein the crystalline matrix (M) has been produced in at least one reactor, preferably in two reactors, and subsequently the elastomeric propylene-ethylene copolymer (EC) has been produced in at least two further reactors, preferably in two further reactors, wherein a first elastomeric propylene-ethylene copolymer fraction (EC1) has been produced in one of the two further reactors and the second elastomeric propylene-ethylene copolymer fraction (EC2) has been produced in the other one of the two further reactors. It is especially preferred that first the first elastomeric propylene-ethylene copolymer fraction (EC1) is produced and subsequently the second elastomeric propylene-ethylene copolymer fraction (EC2) .

The term “polymerization reactor” shall indicate that the main polymerization takes place. Thus in case the process consists of four polymerization reactors, this definition does not exclude the option that the overall process comprises for instance a pre-polymerization step in a pre-polymerization reactor. The term “consist of” is only a closing formulation in view of the main polymerization reactors, i.e. does not exclude prepolymerisation reactors prior to said main polymerization reactors.

Preferably, said process comprises the steps of

(a1) polymerizing propylene in a first reactor (R1) obtaining the first propylene homopolymer fraction (h-PP1) ,

(b1) transferring the first propylene homopolymer fraction (h-PP1) into a second reactor (R2) ,

(c1) polymerizing propylene in the second reactor (R2) in the presence of said first propylene homopolymer fraction (h-PP1) , obtaining thereby the second propylene homopolymer fraction (h-PP2) , the first propylene homopolymer fraction (h-PP1) together with the second propylene homopolymer fraction (h-PP2) forms the crystalline propylene homopolymer matrix (M) ,

(d1) transferring the crystalline propylene homopolymer matrix (M) of step (c1) into a third reactor (R3) ,

(e1) polymerizing propylene and ethylene in the third reactor (R3) in the presence of the crystalline propylene homopolymer matrix (M) obtained in step (c1) , obtaining thereby the first elastomeric propylene-ethylene copolymer fraction (EC1) , said crystalline propylene homopolymer matrix (M) and said first elastomeric propylene-ethylene copolymer fraction (EC1) forming a mixture (M1) ,

(f1) transferring said mixture (M1) into a fourth reactor (R4) , and

(g1) polymerizing propylene and ethylene in the fourth reactor (R4) in the presence of the mixture (M1) , obtaining thereby the second elastomeric propylene-ethylene copolymer fraction (EC2) , the mixture (M1) and the second elastomeric propylene-ethylene copolymer fraction (EC2) forming the heterophasic propylene-ethylene copolymer (HECO) .

Per definition the xylene cold soluble (XCS) of said mixture (M1) is regarded as the first elastomeric propylene-ethylene copolymer fraction (EC1) .

For preferred embodiments of the heterophasic propylene copolymer (HECO) , the crystalline matrix (M) , the first propylene homopolymer (h-PP1) , the second propylene homopolymer (h-PP2) , first elastomeric propylene-ethylene copolymer fraction (EC1) , as well as for the second elastomeric propylene-ethylene copolymer fraction (EC2) reference is made to the definitions given above.

The first reactor (R1) is preferably a slurry reactor (SR) and can be any continuous or simple stirred batch tank reactor or loop reactor operating in bulk or slurry. Bulk means a polymerization in a reaction medium that comprises of at least 60 % (w/w) monomer. According to the present invention the slurry reactor (SR) is preferably a (bulk) loop reactor (LR) .

The second reactor (R2) , the third reactor (R3) and the fourth reactor (R4) are preferably gas phase reactors (GPR) . Such gas phase reactors (GPR) can be any mechanically mixed or fluid bed reactors. Preferably the gas phase reactors (GPR) comprise a mechanically agitated fluid bed reactor with gas velocities of at least 0.2 m/sec. Thus it is appreciated that the gas phase reactor is a fluidized bed type reactor preferably with a mechanical stirrer.

Thus in a preferred embodiment the first reactor (R1) is a slurry reactor (SR) , like loop reactor (LR) , whereas the second reactor (R2) , the third reactor (R3) and the fourth reactor (R4) are gas phase reactors (GPR) . Accordingly for the instant process at least four, preferably four polymerization reactors, namely a slurry reactor (SR) , like loop reactor (LR) , a first gas phase reactor (GPR-1) , a second gas phase reactor (GPR-2) and a third gas phase reactor (GPR-3) connected in series are used. If needed prior to the slurry reactor (SR) a pre-polymerization reactor is placed.

A preferred multistage process is a “loop-gas phase” -process, such as developed by Borealis A/S, Denmark (known as

technology) described e.g. in patent literature, such as in EP 0 887 379, WO 92/12182 WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or in WO 00/68315.

A further suitable slurry-gas phase process is the

process of Basell described e.g. in figure 20 of the paper by Galli and Vecello, Prog. Polym. Sci. 26 (2001) 1287-1336.

Preferably, in the instant process for producing the crystalline matrix (M) as defined above the conditions for the first reactor (R1) , i.e. the slurry reactor (SR) , like a loop reactor (LR) , of step (a1) may be as follows:

- the temperature is within the range of 40 ℃ to 110 ℃, preferably between 60 ℃ and 100 ℃, like 68 to 95 ℃,

- the pressure is within the range of 20 bar to 80 bar, preferably between 40 bar to 70 bar,

- hydrogen can be added for controlling the molar mass in a manner known per se.

Subsequently, the reaction mixture from step (a1) containing preferably the first propylene copolymer fraction (PP1) is transferred to the second reactor (R2) , i.e. the first gas phase reactor (GPR-1) , whereby the conditions are preferably as follows:

- the temperature is within the range of 50 ℃ to 130 ℃, preferably between 60 ℃ and 100 ℃,

- the pressure is within the range of 5 bar to 50 bar, preferably between 15 bar to 35 bar,

If desired, the polymerization may be effected in a known manner under supercritical conditions in the first reactor (R1) , i.e. in the slurry reactor (SR) , like in the loop reactor (LR) , and/or as a condensed mode in the gas phase reactor (GPR-1) .

The gas phase reactors (GPR-2) and (GPR-3) of steps (e1) and (g1) are preferably also operated within the above conditions, preferably with the exception that in gas phase reactors (GPR-2) and (GPR-3)

- the pressure is within the range of 5 bar to 50 bar, preferably between 10 bar to 30 bar.

The residence time can vary in the above different reactors.

In one embodiment of the process for producing the propylene copolymer the residence time the first reactor (R1) , i.e. the slurry reactor (SR) , like a loop reactor (LR) , is in the range 0.2 to 4 hours, e.g. 0.3 to 1.5 hours and the residence time in the gas phase reactors (GPR1 to GPR3) will generally be 0.2 to 6.0 hours, like 0.5 to 4.0 hours.

In the process of the invention a well-known prepolymerization step may precede before the actual polymerization in the reactors (R1) to (R4) . The prepolymerisation step is typically conducted at a temperature of 0 to 50 ℃, preferably from 10 to 45 ℃, and more preferably from 15 to 40 ℃.

More preferably the heterophasic propylene copolymer (HECO) is obtained in the presence of

(I) a solid catalyst component comprising a magnesium halide, a titanium halide and an internal electron donor; and

(II) a cocatalyst comprising an aluminium alkyl and optionally an external electron donor, and

(III) an optional nucleating agent, preferably in the presence of a nucleating agent as defined above or below;

and in a sequential polymerization process as defined in the present invention.

It is especially preferred that the process according to the present invention includes the following process steps:

polymerizing a vinyl compound as defined above, preferably vinyl cyclohexane (VCH) , in the presence of a catalyst system comprising the solid catalyst component to obtain a modified catalyst system which is the reaction mixture comprising the solid catalyst system and the produced polymer of the vinyl compound, preferably, and wherein, the weight ratio (g) of the polymer of the vinyl compound to the solid catalyst system is up to 5 (5: 1) , preferably up to 3 (3: 1) most preferably is from 0.5 (1: 2) to 2 (2: 1) , and the obtained modified catalyst system is fed to polymerization step (a1) of the process for producing the heterophasic propylene copolymer (HECO) .

The used catalyst is preferably a Ziegler-Natta catalyst system and even more preferred a modified Ziegler Natta catalyst system as defined in more detail below.

Such a Ziegler-Natta catalyst system typically comprises a solid catalyst component, preferably a solid transition metal component, and a cocatalyst, and optionally an external donor. The solid catalyst component comprises most preferably a magnesium halide, a titanium halide and an internal electron donor. Such catalysts are well known in the art. Examples of such solid catalyst components are disclosed, among others, in WO 87/07620, WO 92/21705, WO 93/11165, WO 93/11166, WO 93/19100, WO 97/36939, WO 98/12234, WO 99/33842.

Suitable electron donors are, among others, esters of carboxylic acids, like phthalates, citraconates, and succinates. Also oxygen-or nitrogen-containing silicon compounds may be used. Examples of suitable compounds are shown in WO 92/19659, WO 92/19653, WO 92/19658, US 4,347,160, US 4,382,019, US 4,435,550, US 4,465,782, US 4,473,660, US 4,530,912 and US 4,560,671.

Moreover, said solid catalyst components are preferably used in combination with well known external electron donors, including without limiting to, ethers, ketones, amines, alcohols, phenols, phosphines and silanes, for example organosilane compounds containing Si-OCOR, Si-OR, or Si-NR ₂ bonds, having silicon as the central atom, and R is an alkyl, alkenyl, aryl, arylalkyl or cycloalkyl with 1-20 carbon atoms; and well known cocatalysts, which preferably comprise an aluminium alkyl compound as known in the art, to polymerise the propylene copolymer.

When a nucleating agent is introduced to the heterophasic propylene copolymer (HECO) during the polymerisation process of the propylene copolymer, the amount of nucleating agent present in the heterophasic propylene copolymer (HECO) is preferably not more than 500 ppm, more preferably is 0.025 to 200 ppm, still more preferably is 1 to 100 ppm, and most preferably is 5 to 100 ppm, based on the heterophasic propylene copolymer (HECO) and the nucleating agent, preferably based on the total weight of the heterophasic propylene copolymer (HECO) including all additives.

The process for preparing the polyolefin composition (PC)

The present invention is additionally directed to a process for the preparation of the polyolefin composition (PC) of the present invention, comprising the steps of:

a) providing at least one additive (A) , preferably in the form of a master batch;

b) blending the heterophasic propylene-ethylene copolymer (HECO) with the polar-modified polypropylene (MP) to obtain a mixed blend of heterophasic propylene-ethylene copolymer (HECO) and polar-modified polypropylene (PMP) ;

c) providing glass fibers (GF) ;

d) blending and extruding the mixed blend of heterophasic propylene-ethylene copolymer (HECO) and polar-modified polypropylene (PMP) with the at least one additive (A) , and the glass fibers (GF) at a temperature in the range from 120 ℃ to 230 ℃ in an extruder, preferably a twin-screw extruder.

In particular, it is preferred to use a conventional compounding or blending apparatus, e.g. a Banbury mixer, a 2-roll rubber mill, Buss-co-kneader or a twin-screw extruder. More preferably, mixing is accomplished in a co-rotating twin-screw extruder. The polymer materials recovered from the extruder are usually in the form of pellets. These pellets are then preferably further processed, e.g. by injection molding or compression molding to generate articles and products of the inventive polyolefin composition (C) .

The article

The present invention also relates to articles comprising the polyolefin composition (PC) of the invention.

Preferably the article of the invention comprises more than 75 wt. -%of the polyolefin composition (PC) , more preferably more than 85 wt. -%, yet more preferably more than 90 wt. -%, most preferably more than 95 wt. -%of the of the polyolefin composition (PC) .

It is preferred that the polyolefin composition (PC) is the only polyolefin component in the article.

The article is preferably a molded article, most preferably an injection molded article or a foam injection molded article.

Preferably, the article is a part of safety articles, especially of baby vehicle safety seats and safety helmets.

In one preferred embodiment, the article is a baby vehicle safety seat.

In another preferred embodiment, the article is a safety helmet.

EXAMPLES

1. Definitions/Measuring Methods

The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

MFR ₂: The melt flow rate (MFR) is determined according to ISO 1133 and is indicated in g/10 min. The MFR is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR ₂ of polypropylene is determined at a temperature of 230 ℃ and a load of 2.16 kg.

Quantification of copolymer microstructure by NMR spectroscopy

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

Quantitative ¹³C { ¹H} NMR spectra were recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for ¹H and ¹³C respectively. All spectra were recorded using a ¹³C optimised 10 mm extended temperature probehead at 125 ℃ using nitrogen gas for all pneumatics. Approximately 200 mg of 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 relaxation agent in solvent as described in G. Singh, A. Kothari, V. Gupta, Polymer Testing 2009, 28 (5) , 475.

To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatory oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz.This setup was chosen primarily for the high resolution and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE, using an optimised tip angle, 1 s recycle delay and a bi-level WALTZ16 decoupling scheme as described in Z. Zhou, R.

Kuemmerle, X. Qiu, D. Redwine, R. Cong, A. Taha, D. Baugh, B. Winniford, J. Mag. Reson. 187 (2007) 225 and V. Busico, P. Carbonniere, R. Cipullo, C. Pellecchia, J. Severn, G. Talarico, Macromol. Rapid Commun. 2007, 28, 1128. A total of 6144 (6k) transients were acquired per spectra. Quantitative ¹³C { ¹H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present.

With characteristic signals corresponding to 2, 1 erythro regio-defects observed (as described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100 (4) , 1253, in Cheng, H.N., Macromolecules 1984, 17, 1950, and in W-J. Wang and S. Zhu, Macromolecules 2000, 33 1157) the correction for the influence of the regio-defects on determined properties was required. Characteristic signals corresponding to other types of regio-defects were not observed.

Characteristic signals corresponding to the incorporation of ethylene were observed (as described in Cheng, H.N., Macromolecules 1984, 17, 1950) and the comonomer fraction calculated as the fraction of ethylene in the polymer with respect to all monomer in the polymer.

The comonomer fraction was quantified using the method of W-J. Wang and S. Zhu, Macromolecules 2000, 33 1157, through integration of multiple signals across the whole spectral region in the ¹³C { ¹H} spectra.

This method was chosen for its robust nature and ability to account for the presence of regio-defects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

The mole percent comonomer incorporation was calculated from the mole fraction.

The weight percent comonomer incorporation was calculated from the weight fraction.

Calculation of comonomer content of the second elastomeric propylene-ethylene copolymer fraction (EC2) (herein calculated for the second elastomeric propylene-ethylene copolymer fraction (EC2) , but the formula can be applied for the other fractions as well) :

wherein

w (PP1) is the weight fraction [in wt. -%] of the first elastomeric propylene-ethylene copolymer fraction (EC1) , e.g. the xylene cold soluble (XCS) fraction after the third reactor (e.g. comprising the matrix (M) and the first elastomeric fraction) ;

w (PP2) is the weight fraction [in wt. -%] of the second elastomeric propylene-ethylene copolymer fraction (EC2) , e.g. of the amount of xylene cold soluble fraction (XCS) produced in the fourth reactor (e.g. the second elastomeric fraction produced in the fourth reactor) ;

C (PP1) is the comonomer content [in mol-%] of the first elastomeric propylene-ethylene copolymer fraction (EC1) , e.g. of the xylene cold soluble (XCS) fraction after the third reactor (e.g. comprising the matrix (M) and the first elastomeric fraction) ;

C (PP) is the comonomer content [in mol-%] of the xylene soluble fraction of the final heterophasic propylene copolymer (HECO) ,

C (PP2) is the calculated comonomer content [in mol-%] of the second elastomeric propylene-ethylene copolymer fraction (EC2) .

Maleic anhydride content: FT-IR standards are prepared by blending a PP homopolymer with different amounts of MAH to create a calibration curve (absorption/thickness in cm versus MAH content in weight %) . The MAH content is determined in the solid-state by IR spectroscopy using a Bruker Vertex 70 FTIR spectrometer on 25x25 mm square films of 100 μm thickness (with an accuracy of ± 1 μm) prepared by compression molding at 190 ℃ with 4 -6 mPa clamping force. Standard transmission FTIR spectroscopy is employed using a spectral range of 4000-400 cm ^-1, an aperture of 6 mm, a spectral resolution of 2 cm ^-1, 16 background scans, 16 spectrum scans, an interferogram zero filling factor of 32 and Norton Beer strong apodisation.

At the adsorption band peak of 1787 cm ^-1 MAH is measured. For the calculation of the MAH content the range between 1830-1727 cm ^-1 is evaluated (after a base line correction) following the calibration standard curve.

The xylene soluble fraction (XCS) at room temperature (XCS, wt. -%) : The amount of the polymer soluble in xylene is determined at 25 ℃ according to ISO 16152; first edition; 2005-07-01. The remaining part is the xylene cold insoluble (XCU) fraction.

The intrinsic viscosity (IV) is measured according to ISO 1628-1 (at 135 ℃ in decalin) .

The Heat Deformation Temperature (HDT) is determined according to ISO 75-2 Method A (load 1.80 MPa surface stress) using a Ceast 6921 of

GmbH, Germany.

Charpy impact test: The Charpy notched impact strength (NIS) was measured according to ISO 179-1 eA at +23 ℃ and -20 ℃, using injection-molded bar test specimens of 80x10x4 mm ³ prepared in accordance with ISO 1873-2: 2007.

Flexural Modulus: The flexural modulus was determined in 3-point-bending at 23℃ according to ISO 178 on 80x10x4 mm ³ test bars injection molded in line with EN ISO 1873-2.

Tensile Strength: measured according to ISO527 on 170x10x4 mm ³ test bars injection molded in line with EN ISO 1873-2.

Glass transition temperature (T _g) : The glass transition temperature (T _g) is determined by dynamic mechanical analysis according to ISO 6721-7. The measurements are done in torsion mode on compression moulded samples (40x10x1 mm ³) between -100 ℃ and +150 ℃ with a heating rate of 2 ℃/min and a frequency of 1 Hz.

2. Examples

2.1. Synthesis of heterophasic propylene-ethylene copolymer (HECO)

The catalyst used in the polymerizations was a Ziegler-Natta catalyst from Borealis having Ti-content of 1.9 wt-% (as described in EP 591 224) . Before the polymerization, the catalyst was prepolymerized with vinyl-cyclohexane (VCH) as described in EP 1 028 984 and EP 1 183 307. The ratio of VCH to catalyst of 1: 1 was used in the preparation, thus the final Poly-VCH content was less than 100 ppm.

In the first stage the catalyst described above was fed into prepolymerization reactor together with propylene and small amount of hydrogen (2.5 g/h) and ethylene (330 g/h) . Triethylaluminium as a cocatalyst and dicyclopentyldimethoxysilane as a donor was used. The aluminium to donor ratio was 7.5 mol/mol and aluminium to titanium ratio was 300 mol/mol. Reactor was operated at a temperature of 30 ℃ and a pressure of 55 barg.

The subsequent polymerization has been effected under the following conditions.

Table 1: Polymerization conditions for HECO

2.2. Compounding of examples

The propylene compositions of Inventive examples IE1 to IE4 and comparative examples CE1 and CE2 were prepared based on the recipes indicated in Table 2 by compounding in a co-rotating twin-screw extruder under the conditions described in Table 3. The extruder has 11 heating zones.

Table 2: Recipes for Comparative and Inventive examples

h-PP propylene homopolymer with a trade name of HD120MO, commercially available from Borouge Sales &Marketing (Shanghai) . Co. Ltd., Shanghai, China, having an MFR ₂ (230 ℃, 2.16 kg) of 9.0 g/10 min, h-PP is not nucleated with pVCH.

E ethylene-octene elastomeric copolymer with a trade name of Engage 8200, commercially available from Dow Chemicals Inc. (USA) .

PMP maleic anhydride-grafted polypropylene with a trade name of SCONA TPPP 8112 GA, commercially available from BYK-Cera (Germany) , having a maleic anhydride content of 1.4 wt. -%and an MFR ₂ (190 ℃, 2.16 kg) of 100 g/10min.

GF chopped strand glass fibers with a trade name of CS 248A-13P, available from Owens Corning Composites (China) , having nominal diameter of 13 μm and a chop length of 4.0 mm.

A an additive masterbatch, consisting of 1.2 wt. -%of a carrier propylene homopolymer with a trade name of PP-H 225, available from Hongji petrochemical (China) , having an MFR ₂ (230 ℃, 2.16 kg) of 27 g/10 min, 0.5 wt. -%of a carbon black pigment 0.2 wt. -%of an antioxidant blend with a trade name of Irganox 225 (contains 50%Irgafos 168, CAS-no. 31570-04-4 and 50%Irganox 1010, CAS-no. 6683-19-8) , available from BASF SE (Germany) , and 0.1 wt. -%of a UV stabilizer with a trade name of Cyasorb UV-3529 (CAS-no. 193098-40-7) , available from Solvay S.A. (China) .

Table 3: Compounding conditions for Inventive examples in twin-screw extruder

Table 4: Properties of comparative and inventive examples

As can be seen from the examples in Table 4, the inventive examples have a notably improved balance of stiffness (Flexural Modulus) and impact strength (Charpy) . It is notable that not only do the inventive examples have a much better impact strength than the composition based on the propylene homopolymer (CE1) , but also than the composition that contains an impact modifier (Engage 8200) , i.e. CE2.

The heat deflection temperature (HDT) is also superior in the inventive examples, when compared with CE2 (i.e. the only comparative example that even comes close to the desired impact strengths) . This benefits the processability of these compositions and their use.

As discussed previously, the requirements for a baby vehicle safety seat are a minimum stiffness of 5000 MPa and minimum NIS of 25 kJ/m ², making inventive examples IE2-IE4 suitable for such a use, whilst IE3-IE4 are suitable for use in safety helmets (requiring minimum values of 5500 MPa and 25 kJ/m ² respectively) .

Claims

A polyolefin composition (PC) comprising:

a) from 55.0 to 73.0 wt. -%, based on the total weight of the composition, of a heterophasic propylene-ethylene copolymer (HECO) , consisting of:

i) a crystalline propylene homopolymer matrix (M) having a MFR ₂ of less than 80g/10min.;

ii) an elastomeric propylene-ethylene copolymer (EC) ;

b) from 26.0 to 44.0 wt. -%, based on the total weight of the composition, of glass fibers (GF) ;

c) from 0.5 to 5.0 wt. -%, based on the total weight of the composition, of polar-modified polypropylene (PMP) ; and

d) from 0.1 to 5.0 wt. -%, based on the total weight of the composition, of at least one additive (A) other than the glass fibers (GF) and the polar-modified polypropylene (PMP) ,

wherein the HECO has each of the following properties:

i) a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min;

ii) a xylene cold solubles (XCS) content in the range from 30.0 to 45.0 wt. -%; and

iii) an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 30.0 to 45.0 wt. -%,

wherein the polyolefin composition (PC) is free of elastomeric ethylene copolymers, free of fillers other than the glass fibers (GF) , and free of propylene homopolymers other than the crystalline propylene homopolymer matrix (M) and any carrier polymers present in an additive masterbatch within the scope of component d) .
A polyolefin composition (PC) consisting of:

a) from 55.0 to 73.0 wt. -%, based on the total weight of the composition, of a heterophasic propylene-ethylene copolymer (HECO) , consisting of:

i) a crystalline propylene homopolymer matrix (M) having a MFR ₂ of less than 80g/10min.;

ii) an elastomeric propylene-ethylene copolymer (EC) ;

b) from 26.0 to 44.0 wt. -%, based on the total weight of the composition, of glass fibers (GF) ;

c) from 0.5 to 5.0 wt. -%, based on the total weight of the composition, of polar-modified polypropylene (PMP) ; and

d) from 0.1 to 5.0 wt. -%, based on the total weight of the composition, of at least one additive (A) other than the glass fibers (GF) and the polar-modified polypropylene (PMP) ,

wherein the HECO has each of the following properties:

i) a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min;

ii) a xylene cold solubles (XCS) content in the range from 30.0 to 45.0 wt. -%; and

iii) an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 30.0 to 45.0 wt. -%.
The polyolefin composition (PC) according to claim 1 or claim 2, wherein the heterophasic propylene-ethylene copolymer (HECO) has one or more, preferably all, of the following properties:

i) a total ethylene (C2) content in the range from 9.0 to 20.0 wt. -%, preferably in the range from 11.0 to 17.0 wt. -%, most preferably in the range from 12.0 to 14.0 wt. -%; and

ii) an intrinsic viscosity of the xylene cold soluble fraction (IV (XCS) ) in the range from 1.8 to 3.2 dl/g, preferably in the range from 2.1 to 2.9 dl/g, most preferably in the range from 2.3 to 2.7 dl/g.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the heterophasic propylene-ethylene copolymer (HECO) has one or more, preferably all, of the following properties:

i) a flexural modulus, measured according to according to ISO 178 on 80x10x4 mm ³ test bars injection molded in line with EN ISO 1873-2, in the range from 700 to 2000 MPa, more preferably in the range from 800 to 1500 MPa, most preferably in the range from 900 to 1200 MPa;

ii) a Charpy notched impact strength, measured at +23 ℃ according to ISO 179-1 1eA using injection-molded bar test specimens of 80x10x4 mm ³ prepared in accordance with ISO 1873-2: 2007, in the range from 20.0 to 100.0 kJ/m ², more preferably in the range from 40.0 to 80.0 kJ/m ², most preferably in the range from 50.0 to 70.0 kJ/m ²; and

iii) a Charpy notched impact strength, measured at -20 ℃ according to ISO 179-1 1eA using injection-molded bar test specimens of 80x10x4 mm ³ prepared in accordance with ISO 1873-2: 2007, in the range from 5.0 to 30.0 kJ/m ², more preferably in the range from 7.0 to 20.0 kJ/m ², most preferably in the range from 9.0 to 15.0 kJ/m ².
The polyolefin composition (PC) according to any one of the preceding claims, wherein the crystalline propylene homopolymer matrix (M) of the heterophasic propylene-ethylene copolymer (HECO) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 30.0 to 79.0 g/10 min.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the heterophasic propylene-ethylene copolymer (HECO) has an ethylene content of the xylene cold soluble fraction (C2 (XCS) ) in the range from 31.0 to 39.0 wt. -%.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the heterophasic propylene-ethylene copolymer (HECO) comprises a polymeric nucleating agent, preferably a vinyl cycloalkane polymer, more preferably a vinyl cyclohexane polymer, most preferably a vinyl cyclohexane homopolymer.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the glass fibers (GF) are chopped glass fibers, more preferably chopped glass fibers with a nominal diameter in the range from 5 to 30 μm, preferably in the range from 7 to 20 μm, most preferably in the range from 10 to 15 μm, and/or a chop length in the range from 1.0 to 10.0 mm, more preferably in the range from 2.0 to 7.0 mm, most preferably in the range from 3.0 to 5.0 mm.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the polar-modified polypropylene (PMP) has a content of polar groups in the range from 0.5 to 3.0 wt. -%.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the polyolefin composition (PC) has a flexural modulus, measured according to according to ISO 178 on 80x10x4 mm ³ test bars injection molded in line with EN ISO 1873-2, of at least 4500 MPa, and/or an Charpy notched impact strength, measured according to ISO 179-1 1eA using injection-molded bar test specimens of 80x10x4 mm ³ prepared in accordance with ISO 1873-2: 2007, of at least 25.0 kJ/m ².
The polyolefin composition (PC) according to any one of the preceding claims, wherein the polyolefin composition (PC) has a heat deflection temperature, measured according to ISO 75-2 under a load of 1.8 MPa, in the range from 130 to 160 ℃.
The polyolefin composition (PC) according to any one of the preceding claims, wherein the polyolefin composition (PC) has a melt flow rate (MFR ₂) measured according to ISO 1133 at 230 ℃ and 2.16 kg in the range from 5.0 to 30.0 g/10 min.
An article comprising more than 75 wt. -%of the polyolefin composition (C) according to any one of claims 1 to 12, preferably a molded article, most preferably an injection molded article.
The article according to claim 13, wherein the article is a safety article, more preferably a baby vehicle safety seat or a safety helmet.