CN114729168A

CN114729168A - Polyolefin composition having electromagnetic interference shielding properties

Info

Publication number: CN114729168A
Application number: CN201980102569.XA
Authority: CN
Inventors: 周信; 高守超
Original assignee: Borouge Compounding Shanghai Co ltd
Current assignee: Borouge Compounding Shanghai Co ltd
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2022-07-08
Also published as: WO2021109071A1

Abstract

A polyolefin composition (C) comprising: a) melt Flow Rate (MFR) of 55.0 to 90.0 wt%₂) Polypropylene (PP) in the range of 2.0 to 120.0g/10 min; b)2.0 to 10.0 wt% Carbon Nanotubes (CNTs); c)5.0 to 40.0 wt% of an inorganic filler (F); d)0.3 to 1.0% by weight of a dispersant (D); e)0.1 to 5.0% by weight of at least one additive (A) other than the inorganic filler (F) and the dispersant (D).

Description

Polyolefin composition having electromagnetic interference shielding properties

Technical Field

The present invention relates to polyolefin compositions comprising polypropylene, carbon nanotubes and inorganic fillers, dispersants and additives, articles comprising said compositions.

Background

It is well known in the art of polypropylene compositions that carbon nanotubes have long been used in processes such as extrusion and hot compression to produce articles having electromagnetic interference (EMI) shielding properties. That is, it is difficult to manufacture such articles by an injection molding process because it is known that carbon nanotubes aggregate toward the center of a mold, resulting in poor dispersibility of the carbon nanotubes in the articles. It is believed that this problem particularly affects carbon nanotubes due to their nanometer size. This low dispersion directly affects the surface resistivity properties of the article, resulting in an article having relatively poor EMI shielding properties. Other fillers, such as carbon black, can be used to prepare automotive articles having desirable EMI shielding properties. However, the required content of these fillers is very high, which usually results in a reduction of the mechanical properties (stiffness, as given by the flexural modulus, and impact strength). In the automotive industry, these mechanical properties are critical to the function of automotive articles.

Thus, there is a need in the automotive industry to develop compositions that combine favorable EMI shielding properties (i.e., low surface resistivity) with a high balance of stiffness (flexural modulus) and impact strength. Articles comprising the composition would be excellent candidates for, in particular, automotive articles housing electrical equipment, such as instrument panel supports.

Disclosure of Invention

The finding of the present invention is that the addition of an inorganic filler, such as talc, to a polypropylene composition containing carbon nanotubes not only improves the balance of mechanical properties, but also improves the dispersion of the carbon nanotubes within the polymer composition, resulting in a reduced surface resistivity. The presence of carbon nanotubes in the composition is beneficial not only for electromagnetic interference shielding performance, but also for both flexural modulus and impact strength.

The present invention therefore relates to a polyolefin composition (C) comprising

a)55.0 to 90.0 wt. -%, based on the total weight of the composition, of a polypropylene (PP), preferably a copolymer, having a molecular weight of 230 ℃ and 2.16kg according to ISO1133 in the range of 2.0 to 120.0g/10min, preferably in the range of 2.0 to 60.0g/10minMeasured Melt Flow Rate (MFR) of₂)；

b)2.0 to 10.0 wt% Carbon Nanotubes (CNTs), based on the total weight of the composition;

c)5.0 to 40.0 wt% of an inorganic filler (F), based on the total weight of the composition;

d)0.3 to 1.0 wt% based on the total weight of the composition of a dispersant (D);

e)0.1 to 5.0% by weight, based on the total weight of the composition, of at least one additive (A) other than the inorganic filler (F) and the dispersant (D).

In a preferred embodiment the polypropylene (PP) is a heterophasic propylene copolymer.

In another preferred embodiment, the polypropylene (PP) has one or more, preferably all, of the following properties:

i) an ethylene (C2) content in the range of 6.0 to 18.0 wt. -%, preferably in the range of 7.0 to 15.0 wt. -%, most preferably in the range of 8.0 to 12.0 wt. -%;

ii) a Xylene Cold Soluble (XCS) content in the range of 20.0 to 32.0 wt. -%, preferably in the range of 22.0 to 29.0 wt. -%, most preferably in the range of 23.0 to 26.0 wt. -%;

iii) an ethylene content of the xylene cold soluble fraction in the range of 30.0 to 45.0 wt. -%, preferably in the range of 33.0 to 42.0 wt. -%, most preferably in the range of 36.0 to 40.0 wt. -% (C2 (XCS));

iv) intrinsic viscosity of the xylene cold soluble fraction (IV (XCS)) in the range of 2.0 to 4.0dl/g, preferably in the range of 2.5 to 3.7dl/g, most preferably in the range of 3.0 to 3.4 dl/g.

In another preferred embodiment, the carbon nanotubes have a molecular weight in the range of 1.8 to 2.1g/cm³A density in the range, and/or a diameter in the range of 2.0 to 25.0nm, and/or a length in the range of 0.1 to 10.0 μm.

In another preferred embodiment, the inorganic filler (F) has an average particle size (d) in the range of from 0.8 to 40 μm₅₀) Preferably selected from the group consisting of talc, calcium carbonate, barium sulfate, micaAnd mixtures thereof, most preferably, the inorganic filler (F) is talc.

In another preferred embodiment, the dispersant (D) is selected from the group consisting of calcium stearate, polyethylene wax, oleamide, erucamide and mixtures thereof, preferably the dispersant (D) is oleamide.

In another preferred embodiment, the polymer composition (C) further comprises

f) 0.1 to 3.0 wt. -%, based on the total weight of the composition, of a Polar Modified Polypropylene (PMP), preferably a maleic anhydride modified polypropylene.

In a further preferred embodiment, the Polar Modified Polypropylene (PMP) has a polar group loading in the range of 0.5 to 3.0 wt%.

In another preferred embodiment, the polyolefin composition (C) has a flexural modulus of at least 1800MPa, and/or of at least 8.0kJ/m²The impact strength of the gap of the simply supported beam.

In another preferred embodiment, the polyolefin composition (C) has a value of at most 1000000Ohm/m²The surface resistivity of (a).

In another aspect, the present invention relates to a process for preparing said polyolefin composition comprising the steps of:

a) providing a mixture of additive (a) and dispersant (D) and optionally Polar Modified Polypropylene (PMP), preferably in the form of a masterbatch;

b) providing Polypropylene (PP);

c) blending Carbon Nanotubes (CNTs) and an inorganic filler (F) to obtain a mixed blend of Carbon Nanotubes (CNTs) and inorganic filler (F);

d) the polypropylene (PP) is blended and extruded with a mixture of additives (a) and dispersants (D) and a blend of Carbon Nanotubes (CNT) and inorganic filler (F) in an extruder, preferably a twin screw extruder, at a temperature in the range of 180 ℃ to 250 ℃.

In another aspect, the present invention relates to an article, preferably a molded article, most preferably an injection molded article or a foamed injection molded article, comprising more than 75% by weight of the polyolefin composition (C).

In a preferred embodiment, the article is part of an automotive article, in particular an automotive interior and exterior trim, such as an instrument holder, hood, structural support, bumper, side trim (side trim), step assist, body panel, spoiler, instrument panel, interior trim (interior trim) and the like.

In another aspect, the present invention relates to the use of a polyolefin composition (C) for the preparation of automotive articles having improved electromagnetic interference shielding properties.

Detailed Description

The present invention will now be described in more detail.

Polypropylene (PP)

The main component of the polyolefin composition is polypropylene (PP).

The polypropylene (PP) of the invention has a Melt Flow Rate (MFR) measured according to ISO1133 at 230 ℃ and 2.16kg in the range of 2.0 to 120.0g/10min, preferably in the range of 2.0 to 60.0g/10min, more preferably in the range of 3.0 to 40.0g/10min, still more preferably in the range of 4.0 to 20.0g/10min, most preferably in the range of 5.0 to 10.0g/10min₂)。

The polypropylene (PP) of the present invention is preferably a copolymer of propylene, more preferably a copolymer of propylene and ethylene and/or an α -olefin having 4 to 12 carbon atoms, most preferably the polypropylene (PP) of the present invention is a copolymer of propylene and ethylene.

It is particularly preferred that the polypropylene (PP) of the present invention is a heterophasic propylene copolymer (HECO).

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

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

Preferably, the polypropylene of the present inventionThe alkene (PP) has a quantitative yield in the range of 6.0 to 18.0 wt.%, preferably in the range of 7.0 to 15.0 wt.%, most preferably in the range of 8.0 to 12.0 wt%¹³Comonomer content by C-NMR spectroscopy.

Preferably, the polypropylene (PP) of the invention has a basis weight in the range of 6.0 to 18.0 wt. -%, preferably in the range of 7.0 to 15.0 wt. -%, most preferably in the range of 8.0 to 12.0 wt. -%¹³Ethylene (C2) content as determined by C-NMR spectroscopy.

Preferably, the polypropylene (PP) of the present invention has a Xylene Cold Soluble (XCS) content in the range of 20.0 to 32.0 wt. -%, preferably in the range of 22.0 to 29.0 wt. -%, most preferably in the range of 23.0 to 26.0 wt. -%.

Preferably, the polypropylene (PP) of the present invention has an ethylene content of the xylene cold soluble fraction (C2(XCS)) in the range of 30.0 to 45.0 wt. -%, preferably in the range of 33.0 to 42.0 wt. -%, most preferably in the range of 36.0 to 40.0 wt. -%.

Preferably, the polypropylene (PP) of the invention has an intrinsic viscosity (IV (XCS)) of the xylene cold soluble fraction in the range of 2.0 to 4.0dl/g, preferably in the range of 2.5 to 3.7dl/g, most preferably in the range of 3.0 to 3.4 dl/g.

Preferably, the polypropylene (PP) of the present invention has a flexural modulus measured according to ISO 178 in the range of 800 to 1500MPa, more preferably in the range of 900 to 1400MPa, still more preferably in the range of 1000 to 1300MPa, most preferably in the range of 1050 to 1200 MPa.

Preferably, the polypropylene (PP) of the invention has a molecular weight in the range of 20.0 to 100.0kJ/m²In the range of 30.0 to 90.0kJ/m²In the range of, still more preferably, 40.0 to 85.0kJ/m²In the range of, most preferably, 50.0 to 80.0kJ/m²Simple beam notched impact strength measured at +23 ℃ according to ISO 179/1eA in the range.

Preferably, the polypropylene (PP) of the invention has a molecular weight in the range of 3.0 to 30.0kJ/m²In the range of 4.5 to 25.0kJ/m, more preferably²In the range of still more preferably 6.0 to 20.0kJ/m²In the range of, most preferably, 7.5 to 15.0kJ/m²Simple beam notched impact strength measured at-20 ℃ according to ISO 179/1eA in the range.

The polypropylene (PP) of the present invention may be synthetic or selected from commercially available polypropylenes.

Carbon Nanotubes (CNT)

As a further essential component, the polyolefin composition (C) comprises Carbon Nanotubes (CNTs).

Preferably, the Carbon Nanotubes (CNTs) have a molecular weight of 1.8 to 2.1g/cm³Density within the range.

It is further preferred that the Carbon Nanotubes (CNTs) have a diameter in the range of 2.0 to 25.0nm, more preferably in the range of 3.0 to 15.0nm, most preferably in the range of 3.0 to 8.0 nm.

It is further preferred that the Carbon Nanotubes (CNTs) have a length in the range of 0.1 to 10.0 μm, more preferably in the range of 1.0 to 8.0 μm, most preferably in the range of 2.0 to 6.0 μm.

Suitable carbon nanotubes include multi-walled carbon nanotubes from CNT Solution co.

Inorganic filler (F)

Another essential component of the polyolefin composition (C) is an inorganic filler (F).

Preferably, the inorganic filler is selected from the group consisting of talc, calcium carbonate, barium sulfate, mica and mixtures thereof.

Most preferably, the inorganic filler (F) is talc.

Preferably, the inorganic filler (F) has an average particle size (d) in the range of 0.8 to 40.0 μm₅₀) More preferably d in the range of 0.8 to 20.0 μm₅₀Especially more preferably d in the range of 1.0 to 10.0. mu.m₅₀。

Preferably, the inorganic filler (F) has an average particle size (d) in the range of 1.0 to 45.0. mu.m₉₅) More preferably d in the range of 2.0 to 20.0 μm₉₅Especially more preferably d in the range of 3.0 to 10.0. mu.m₉₅。

Preferably, the inorganic filler (F) has a particle size of 1.0 to 30.0m²Specific surface in the range of/gProduct B.E.T, more preferably in the range of 5.0 to 20.0m²B.E.T in the range of/g, particularly preferably from 8.0 to 15.0m²B.E.T in the range of/g.

Dispersant (D)

As a further essential component, the polyolefin composition comprises a dispersant (D).

The dispersant is a polyolefin additive which helps to disperse the inorganic filler and the carbon nanotubes in the polyolefin composition (C).

Preferably, the dispersant (D) is selected from the group consisting of calcium stearate, polyethylene wax, oleamide, erucamide and mixtures thereof.

Most preferably, the dispersant (D) is oleamide.

Additive (A)

The polyolefin composition (C) of the present invention may comprise the additive (a) in an amount of 0.1 to 5.0 wt.%. The skilled practitioner will be able to select suitable additives well known in the art.

The additive (a) is preferably selected from the group consisting of antioxidants, uv stabilizers, anti-scratching agents, mold release agents, acid scavengers, lubricants, antistatic agents and mixtures thereof.

It is understood that the content of additive (a) given with respect to the total weight of the polyolefin composition (C) includes any carrier polymer used for introducing the additive into said polyolefin composition (C), i.e. a masterbatch carrier polymer. An example of such a carrier polymer is a polypropylene homopolymer in powder form.

Polarity Modified Polypropylene (PMP)

In certain preferred embodiments, the polyolefin composition (C) of the invention may further comprise a Polar Modified Polypropylene (PMP).

While not wishing to be bound by any theory, it is believed that the Polar Modified Polypropylene (PMP) acts as a compatibilizer in the composition, which further helps to disperse the inorganic filler and the carbon nanotubes within the polyolefin composition (C).

Preferably, the Polar Modified Polypropylene (PMP) has a polar group content in the range of 0.5 to 3.0 wt. -%, more preferably in the range of 0.8 to 2.0 wt. -%, most preferably in the range of 1.0 to 1.5 wt. -%.

It is also preferred that the Polar Modified Polypropylene (PMP) has a Melt Flow Rate (MFR) measured according to ISO1133 at 230 ℃ and 2.16kg of at least 30.0g/10min, more preferably at least 50.0g/10min, still more preferably at least 70g/10min, most preferably at least 80g/10min₂)。

It is especially preferred that the Polar Modified Polypropylene (PMP) is a maleic anhydride modified polypropylene.

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

Polyolefin compositions

The polyolefin composition of the present invention comprises several essential components including polypropylene (PP), Carbon Nanotubes (CNT), inorganic filler (F), dispersant (D) and at least one additive (a) other than inorganic filler (F) and dispersant (D). Accordingly, the polyolefin composition (C) comprises:

a)55.0 to 90.0 wt. -%, based on the total weight of the composition, of a polypropylene (PP) having a Melt Flow Rate (MFR) measured according to ISO1133 at 230 ℃ and 2.16kg in the range of 2.0 to 120.0g/10min₂)；

The polyolefin composition (C) may further comprise:

f) 0.1 to 3.0 wt% of Polar Modified Polypropylene (PMP), based on the total weight of the composition.

The Polypropylene Composition (PC) of the present invention may comprise other components in addition to the essential components as defined above. However, it is preferred that the respective contents of the polypropylene (PP), the Carbon Nanotubes (CNT), the inorganic filler (F), the dispersant (D), the additive (a) and the optional Polar Modified Polypropylene (PMP) sum up to at least 90 wt. -%, more preferably to at least 95 wt. -%, based on the total weight of the Polypropylene Composition (PC). Most preferably, the Polypropylene Composition (PC) consists of polypropylene (PP), Carbon Nanotubes (CNT), inorganic filler (F), dispersant (D), additive (a) and optionally Polar Modified Polypropylene (PMP) only.

The polypropylene (PP) is present in the polyolefin composition in an amount of 55.0 to 90.0 wt. -%, more preferably in an amount of 65.0 to 80.0 wt. -%, most preferably in an amount of 68.0 to 75.0 wt. -%, based on the total weight of the composition.

The Carbon Nanotubes (CNTs) are present in the polyolefin composition in an amount of 2.0 to 10.0 weight%, based on the total weight of the composition, more preferably in an amount of 2.5 to 9.0 weight%, based on the total weight of the composition, most preferably in an amount of 3.0 to 8.0 weight%, based on the total weight of the composition.

The inorganic filler (F) is present in the polyolefin composition in an amount of from 5.0 to 40.0 wt. -%, more preferably in an amount of from 10.0 to 30.0 wt. -%, most preferably in an amount of from 15.0 to 25.0 wt. -%, based on the total weight of the composition.

The dispersant (D) is present in the polyolefin composition in an amount of from 0.3 to 1.0 wt. -%, based on the total weight of the composition, more preferably in an amount of from 0.4 to 0.9 wt. -%, based on the total weight of the composition, most preferably in an amount of from 0.5 to 0.8 wt. -%, based on the total weight of the composition.

Preferably, the Polar Modified Polypropylene (PMP) is present in the polyolefin composition in an amount of from 0.1 to 3.0 wt. -%, more preferably in an amount of from 0.3 to 2.0 wt. -%, most preferably in an amount of from 0.5 to 1.5 wt. -%, based on the total weight of the composition.

Thus, in a preferred embodiment, the polyolefin composition comprises, preferably consists of:

e)0.1 to 5.0% by weight, based on the total weight of the composition, of at least one additive (A) other than the inorganic filler (F) and the dispersant (D);

f) optionally 0.1 to 3.0 wt% of Polar Modified Polypropylene (PMP), based on the total weight of the composition.

Thus, in a further preferred embodiment, the polyolefin composition comprises, preferably consists of:

a) 65.0 to 80.0 wt. -%, based on the total weight of the composition, of a polypropylene (PP) having a Melt Flow Rate (MFR) measured according to ISO1133 at 230 ℃ and 2.16kg in the range of 2.0 to 120.0g/10min₂)；

b) 2.5 to 9.0 wt% Carbon Nanotubes (CNTs), based on the total weight of the composition;

c) 10.0 to 30.0 wt% of an inorganic filler (F), based on the total weight of the composition;

d) 0.4 to 0.9 wt% based on the total weight of the composition of a dispersant (D);

f) optionally 0.3 to 2.0 wt% of Polar Modified Polypropylene (PMP), based on the total weight of the composition.

Thus, in yet another preferred embodiment, the polyolefin composition comprises, preferably consists of:

a) based on68.0 to 75.0 wt. -%, based on the total weight of the composition, of a polypropylene (PP) having a Melt Flow Rate (MFR) measured according to ISO1133 at 230 ℃ and 2.16kg in the range of 2.0 to 120.0g/10min₂)；

b) 3.0 to 8.0 wt% Carbon Nanotubes (CNTs), based on the total weight of the composition;

c) 15.0 to 25.0 wt% of an inorganic filler (F), based on the total weight of the composition;

d) 0.5 to 0.8 wt% based on the total weight of the composition of a dispersant (D);

f) optionally 0.5 to 1.5 wt% of Polar Modified Polypropylene (PMP), based on the total weight of the composition.

In order to be suitable for automotive articles having electromagnetic interference shielding properties, the polyolefin composition (C) according to the present invention requires, in addition to good electromagnetic shielding properties, also advantageous mechanical properties such as stiffness and impact strength.

It is therefore preferred that the polyolefin composition (C) has a flexural modulus measured according to ISO 178 of at least 1800MPa, more preferably at least 1900MPa, most preferably at least 2000 MPa.

The flexural modulus will not normally exceed 2500 MPa.

It is also preferred that the polyolefin composition (C) has a density of at least 8.0kJ/m²More preferably at least 8.5kJ/m²Most preferably at least 9.0kJ/m²Measured according to ISO 179/1eA at +23 ℃.

The flexural modulus is usually not more than 20.0kJ/m²。

Furthermore, it is preferred that the polyolefin composition (C) has a maximum of 1000000Ohm/m²More preferably at most 500000Ohm/m²Most preferably at most 200000Ohm/m²The surface resistivity of (a).

Preparation method for polypropylene (PP)

The polypropylene (PP) comprised in the composition according to the present 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 process for preparing polypropylene is a process for producing a heterophasic propylene copolymer (HECO) comprising a polypropylene homopolymer crystalline matrix (M) and an elastomeric ethylene-propylene copolymer (EC).

Preferably, the heterophasic propylene 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 ethylene-propylene copolymer (EC) has been produced in at least two further reactors, preferably in two further reactors, wherein the first elastomeric ethylene-propylene copolymer fraction (EC1) has been produced in one of the two further reactors and the second elastomeric ethylene-propylene copolymer fraction (EC2) has been produced in the other of the two further reactors. It is particularly preferred to first produce a first elastomeric ethylene-propylene copolymer fraction (EC1) and subsequently produce a second elastomeric ethylene-propylene copolymer fraction (EC 2).

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 e.g. a prepolymerization step in a prepolymerization reactor. The term "consisting of" is only a closed description in terms of the main polymerization reactor, i.e. does not exclude a prepolymerization reactor.

Preferably, the method comprises the steps of:

(a1) in a first reactor (R1) propylene and optionally ethylene and/or at least one C₄To C₁₂Polymerizing alpha-olefins obtaining a first polypropylene fraction (PP1), preferably said first polypropylene fraction (PP1) is a first propylene homopolymer fraction (H-PP1),

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

(c1) in the second reactor (R2) and in thePropylene and optionally ethylene and/or C in the presence of a first polypropylene fraction (PP1)₄To C₁₂Polymerizing an alpha-olefin, thereby obtaining a second polypropylene fraction (PP2), preferably said second polypropylene fraction (PP2) is a second propylene homopolymer fraction (H-PP2), the first polypropylene fraction (PP1) together with the second polypropylene fraction (PP2) forming a crystalline matrix (M),

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

(e1) reacting propylene and ethylene and optionally C in a third reactor (R3) and in the presence of the polypropylene (PP) obtained in step (C1)₄To C₁₂Polymerizing an alpha-olefin, thereby obtaining a first elastomeric ethylene-propylene copolymer fraction (EC1), the crystalline matrix (M) and the first elastomeric ethylene-propylene copolymer fraction (EC1) forming a mixture (M1),

(f1) transferring the mixture (M1) to a fourth reactor (R4), and

(g1) in a fourth reactor (R4) and in the presence of a mixture (M1) propylene and ethylene and optionally C₄To C₁₂The alpha-olefin is polymerized, whereby a second elastomeric ethylene-propylene copolymer fraction (EC2) is obtained, the mixture (M1) and the second elastomeric ethylene-propylene copolymer fraction (EC2) forming a heterophasic propylene copolymer (HECO).

The Xylene Cold Soluble (XCS) of the mixture (M1) is considered by definition to be the first elastomeric ethylene-propylene copolymer fraction (EC 1).

Preferably, in steps (e1) and (g1), only propylene and ethylene are polymerized. Thus, C is preferably absent in steps (e1) and (g1)₄To C₁₂An alpha-olefin.

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

The first reactor (R1) is preferably a Slurry Reactor (SR) and may be any continuous or simple stirred batch tank reactor or loop reactor operating in bulk or in slurry. Bulk refers to polymerization in a reaction medium comprising 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 Reactor (GPR) may be any mechanically mixed or fluidized bed reactor. Preferably, the Gas Phase Reactor (GPR) comprises a mechanically stirred fluidized bed reactor having a gas velocity of at least 0.2 m/s. It will therefore be 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), such as a Loop Reactor (LR), while the second reactor (R2), the third reactor (R3) and the fourth reactor (R4) are Gas Phase Reactors (GPR). Thus, for the process of the present invention, at least four polymerization reactors, preferably four polymerization reactors, i.e. Slurry Reactors (SR), such as Loop Reactors (LR), first gas phase reactor (GPR-1), second gas phase reactor (GPR-2) and third gas phase reactor (GPR-3) connected in series are used. If desired, a prepolymerization reactor is placed before the Slurry Reactor (SR).

A preferred multi-stage process is a "loop-gas phase" process, such as developed by Borealis A/S of Denmark (referred to as

Techniques) are described, for example, in patent documents such as EP 0887379, WO 92/12182, WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or WO 00/68315.

Another suitable slurry-gas phase process is Basell

Methods such as those described in FIG. 20 of the paper prog.Polym.Sci.26(2001)1287-1336 by Galli and Vecello.

Preferably, in the process of the invention for the production of a crystalline matrix (M) as defined above, the conditions of the first reactor (R1), i.e. the Slurry Reactor (SR), such as the Loop Reactor (LR), used in step (a1) may be the following conditions:

-a temperature in the range of 40 ℃ to 110 ℃, preferably between 60 ℃ and 100 ℃, such as 68 to 95 ℃,

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

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

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

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

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

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

If desired, the polymerization can be carried out in a known manner under supercritical conditions in the first reactor (R1), i.e.in a Slurry Reactor (SR), e.g.in a Loop Reactor (LR), and/or in condensed mode in a 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-mentioned conditions, preferably, in addition to the gas phase reactors (GPR-2) and (GPR-3),

-a pressure in the range of 5 to 50 bar, preferably between 10 and 30 bar.

The residence time may be different in the different reactors described above.

In one embodiment of the process for producing propylene copolymers, the residence time in the first reactor (R1), i.e. Slurry Reactor (SR), such as Loop Reactor (LR), is in the range of 0.2 to 4 hours, e.g. in the range of 0.3 to 1.5 hours, whereas the residence time in the gas phase reactor (GPR1 to GPR3) is typically in the range of 0.2 to 6.0 hours, such as 0.5 to 4.0 hours.

In the process of the present invention, prior to the actual polymerization in the reactors (R1) to (R4), a well-known prepolymerization step can be carried out. The pre-polymerisation step is generally carried out at a temperature of from 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 aluminum alkyl and optionally an external electron donor, and

(III) optionally a nucleating agent, preferably in the presence of a nucleating agent as defined above or below.

It is particularly preferred that the method according to the invention comprises the following method steps:

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

The catalyst used is preferably a ziegler-natta catalyst system, even more preferably a modified ziegler-natta catalyst system as defined in more detail below.

Such ziegler-natta catalyst systems generally comprise a solid catalyst component, preferably a solid transition metal component, and a cocatalyst, and optionally an external donor. The solid catalyst component most preferably comprises 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 in, inter alia, WO87/07620, WO 92/21705, WO 93/11165, WO 93/11166, WO 93/19100, WO 97/36939, WO98/12234, WO 99/33842.

Suitable electron donors are especially carboxylic acid esters, such as phthalic acid esters, citraconic acid esters and succinic acid esters. Oxygen-or nitrogen-containing silicon compounds may also 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.

Furthermore, the solid catalyst component is preferably used in combination with well-known external electron donors and well-known cocatalysts for polymerizing propylene copolymers, the external electron donors including, but not limited to, ethers, ketones, amines, alcohols, phenols, phosphines and silanes, e.g. containing Si-OCOR, Si-OR OR Si-NR₂A bond, an organosilane compound having silicon as a central atom, and R is an alkyl group, an alkenyl group, an aryl group, an aralkyl group or a cycloalkyl group having 1 to 20 carbon atoms; the cocatalyst preferably comprises an alkylaluminum compound known in the art.

When a nucleating agent is introduced into the heterophasic propylene copolymer (HECO) during the polymerization process of the propylene copolymer, the amount of nucleating agent present in the heterophasic propylene copolymer (HECO) is preferably not more than 500ppm, more preferably 0.025 to 200ppm, still more preferably 1 to 100ppm, and most preferably 5 to 100ppm, 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.

Process for preparing the polyolefin composition (C)

The present invention also relates to a process for preparing the polyolefin composition (C) of the invention, comprising the steps of:

b) providing Polypropylene (PP);

In particular, it is preferred to use conventional compounding or blending equipment, such as a Banbury mixer, a two-roll rubber mill, a Buss-co-kneader (Buss-co-kneader), or a twin-screw extruder. More preferably, the mixing is done in a co-rotating twin screw extruder. The polymeric material recovered from the extruder is typically in the form of pellets. These pellets are then preferably further processed, for example by compression moulding, to give articles and products of the polyolefin composition (C) of the invention.

Article and use

The invention also relates to articles comprising the polyolefin compositions (C) of the invention.

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

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

Preferably, the article is part of an automotive article, in particular part of an automotive interior, such as an instrument holder, an instrument panel, an interior trim or the like.

The present invention relates to the use of a polyolefin composition (C) for the preparation of automotive articles having improved electromagnetic interference shielding properties.

Examples

1. Defining/measuring method

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

The density was measured according to ISO 1183-. Sample preparation was done by compression moulding according to ISO 1872-2: 2007.

Melting temperature T_mMeasured according to ISO 11357-3.

MFR₂: the Melt Flow Rate (MFR) is determined according to ISO1133 and is expressed in g/10 min. The MFR characterizes the flowability of the polymer and thus the processability of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. MFR of Polypropylene₂Measured at a temperature of 230 ℃ and under a load of 2.16 kg.

Quantification of copolymer microstructure by NMR spectroscopy

The comonomer content of the polymer was quantified using quantitative Nuclear Magnetic Resonance (NMR) spectroscopy.

Adopt to¹H and¹³c Bruker Advance III 400NMR spectrometers operating at 400.15 and 100.62MHz respectively record quantitative measurements in solution¹³C{¹H } NMR spectrum. Use of¹³C-optimized 10mm extended temperature probe all spectra were recorded at 125 ℃, using nitrogen for all pneumatic devices. About 200mg of material was mixed with chromium (III) acetylacetonate (Cr (acac)₃) Dissolved together in 3ml of 1, 2-tetrachloroethane-d₂(TCE-d₂) A 65mM solution of the relaxant in a solvent was obtained as described in g.singh, a.kothari, v.gupta, Polymer Testing 2009,28(5), 475.

To ensure homogeneity of the solution, after initial sample preparation in the heating block, the NMR tube was further heated in a rotary oven for at least 1 hour. After insertion into the magnet, the tube was rotated at 10 Hz. This setting is chosen primarily for the quantitative need of the setting for high resolution and accurate ethylene content quantification. Using standard single pulse excitation without NOE, optimized tip angle (tip angle), 1s of cycle delay and dual stage WALTZ16 decoupling schemes were used as described in z.zhou, r.kuemmerle, x.qiu, d.redwine, r.conv, a.taha, d.baugh, b.winnoford, j.mag.reson.187(2007)225 and v.busico, p.carbonniere, r.cipullo, c.pelletcchia, j.seven, g.talaro, macromol.rapid commun.2007,28,1128. A total of 6144(6k) transients were collected for each spectrum. Will quantify¹³C{¹H NMR spectra were processed, integrated and the relevant quantitative properties were determined from the integration. Chemical shifts using solvents, all chemistryThe shifts refer indirectly to the central methylene group of the ethylene block (EEE) at 30.00 ppm. This approach allows comparable referencing even if the structural unit is not present.

Characteristic signatures corresponding to 2,1 erythro domain defects (as described in l.resconi, l.cavalo, a.fat, f.Piemontesi, chem.Rev.2000,100(4),1253, Cheng, H.N., Macromolecules 1984,17,1950 and W-j.Wang and s.Zhu, Macromolecules 2000,331157) were observed, and the effect of the domain defects on the determined performance needs to be corrected. No characteristic signals corresponding to other types of area defects were observed.

A characteristic signal corresponding to ethylene incorporation was observed (as described in Cheng, h.n., Macromolecules 1984,17, 1950) and the comonomer fraction was calculated as the fraction of ethylene in the polymer relative to all monomers in the polymer.

Wang and S.Zhu, Macromolecules 2000,331157 by the method described in¹³C{¹H } integration of multiple signals over the entire spectral region of the spectrum quantifies comonomer fraction. This method was chosen for its robustness and ability to account for the presence of regional defects when needed. The integration region is adjusted slightly to improve the applicability over the entire range of comonomer contents encountered.

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

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

The comonomer content of the second elastomeric ethylene-propylene copolymer fraction (EC2) was calculated (used herein to calculate the second elastomeric ethylene-propylene copolymer fraction (EC2), but the formula also applies to the other fractions):

wherein

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

w (PP2) is the weight fraction [ in wt. -% ] of the amount of the second elastomeric ethylene-propylene copolymer fraction (EC2), e.g. the 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 ethylene-propylene copolymer fraction (EC1), e.g. the Xylene Cold Soluble (XCS) fraction (e.g. comprising matrix (M) and first elastomeric fraction) after the third reactor;

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 mole%) of the second elastomeric ethylene-propylene copolymer fraction (EC 2).

Maleic anhydride content: FT-IR standards were prepared by blending PP homopolymer with different amounts of MAH to create a calibration curve (absorption/thickness (cm) versus MAH content (wt%)). The MAH content was determined by infrared spectroscopy in the solid state using a Bruker Vertex 70FTIR spectrometer on a 25X 25mm square film having a thickness of 100 μm (precision. + -. 1 μm) prepared by compression moulding at 190 ℃ with a clamping force of 4 to 6 mPa. Using standard transmission FTIR spectroscopy, the spectral range used was 4000 to 400cm^-1Aperture of 6mm and spectral resolution of 2cm^-116 background scans, 16 spectral scans, an interferogram with a zero fill factor of 32 and a Norton Beer strong apodization were performed.

At 1787cm^-1MAH is measured at the absorption spectrum peak of (a). For the calculation of the MAH content, 1830 to 1727cm were evaluated according to a calibration standard curve^-1After baseline correction).

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

Intrinsic Viscosity (IV) was measured according to ISO 1628-1 (in decalin at 135 ℃).

Impact test of simply supported beam: the simple beam Notched Impact Strength (NIS) is 80X 10X 4mm prepared according to ISO 1873-2:2007 at +23 ℃ and-20 ℃ according to ISO 179-1eA³The injection molded rod specimen of (1) was measured.

Flexural modulus: the flexural modulus is 80X 10X 4mm injection-molded at 23 ℃ according to ISO 178 in accordance with EN ISO 1873-2³Measured on a test bar with a 3-point bend.

Tensile strength: 170X 10X 4mm injection moulded in accordance with EN ISO 1873-2³Measured on test bars according to ISO 527.

Particle size d₅₀And top cut (top cut) d₉₅Particle size distribution [ mass percent ] determined by the liquid gravity sedimentation method (sedimentation diagram) according to ISO 13317-3]And (4) calculating.

Surface resistivity: measurements were carried out on test specimens, i.e. 150mm (length) 90mm (width) 3mm (height) panels injection moulded according to EN ISO 1873-2, using a test equipment "HS-699" from heuson electronics Ltd, shenzhen, guangdong, china, under test conditions of a temperature of 23 ℃ and a relative humidity of 50%.

2. Examples of the embodiments

2.1 Synthesis of Polypropylene (PP1)

The catalyst used in the polymerization was a ziegler-natta catalyst from Borealis with a titanium content of 1.9 wt.% (as described in EP 591224). Prior to polymerization, the catalyst was prepolymerized with vinyl-cyclohexane (VCH) as described in EP 1028984 and EP 1183307. The ratio of VCH to catalyst used in the preparation was 1:1, so the final poly-VCH content was below 100 ppm.

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

The subsequent polymerization was carried out under the following conditions.

Table 1: polymerization conditions for PP1

2.2. Compounding of the examples

The propylene compositions of examples IE1 to IE3 and comparative examples CE1 and CE2 of the present invention were prepared based on the formulations shown in table 2 by compounding in a co-rotating twin-screw extruder under the conditions described in table 3. The extruder had 11 heating zones.

Table 2: formulations for comparative and inventive examples

PP2 propylene homopolymer available under the trade name HD915CF from Borough Sales, Shanghai, China&Market (shanghai) co.ltd. commercially available, MFR₂It was 8g/10 min.

PP3 propylene homopolymer available under the trade name HJ311AI from Borough Sales, Shanghai, China&Market (shanghai) co.ltd. commercially available, MFR₂Is 62g/10min

CNTs Multi-walled carbon nanotubes commercially available from CNT Solution (Korea) having a diameter of 5nm, a length of 4 μm, and a density of 1.9g/cm³；

F Talc with the trade name Jetfine T1CA, commercially available from Imerys (France), median diameter d₅₀1.3 μm, diameter d₉₅Is 4.2 μm and has a specific surface area BET of 12.6m²/g；

D oleamide dispersant, available commercially from Croda Chemicals Europe Ltd (UK), CAS-number 301-02-0, melting point 75 ℃;

PMP maleic anhydride grafted polypropylene, available under the trade name SCONA TPPP 8112GA, commercially available from BYK-Cera (Germany), has a maleic anhydride content of 1.4% by weight.

Tris (2, 4-di-tert-butylphenyl) phosphite (CAS-number 31570-04-4) as antioxidant Irgafos 168BASF SE, with a melting temperature of 182 ℃;

irganox 1010BASF SE antioxidant pentaerythrityl tetrakis (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS-No. 6683-19-8), melt temperature 115 ℃;

a propylene homopolymer carrier of h-PP additive, in powder form, with a melting temperature of 160 ℃;

CB carbon black

Yuch black-1906Yuch black-1906 pigment, commercially available from Cabot corporation (USA)

Table 3: compounding conditions for comparative and inventive examples

Table 4: performance of comparative examples and inventive examples

As can be seen from the examples in table 4, the compositions containing both carbon nanotubes and filler (i.e., IE1 through IE3) had much lower surface resistivity than the examples without talc (CE2), and much lower surface resistivity than the typical carbon black-based compositions (CE1) often used in similar applications.

Furthermore, the examples of the present invention clearly show a significantly improved balance of mechanical properties (flexural modulus and simple beam NIS) compared to the comparative examples. The presence of carbon nanotubes in the composition appears to improve both flexural modulus and simple beam NIS (compare IE1, IE2 and IE3), which is a difficult effect to achieve in polypropylene compositions.

The combination of the desirable balance of mechanical properties with improved electromagnetic interference shielding properties (i.e., low surface resistivity) makes the compositions of the present invention ideal candidates for use in the manufacture of automotive articles (e.g., instrument panel supports) that are involved in housing electrical equipment.

Claims

1. A polyolefin composition (C) comprising

a)55.0 to 90.0 wt. -%, based on the total weight of the composition, of a polypropylene (PP), preferably a copolymer, having a Melt Flow Rate (MFR) measured according to ISO1133 at 230 ℃ and 2.16kg in the range of 2.0 to 120.0g/10min, preferably in the range of 2.0 to 60.0g/10min₂)；

b)2.0 to 10.0 wt% Carbon Nanotubes (CNTs) based on the total weight of the composition;

e)0.1 to 5.0 wt. -%, based on the total weight of the composition, of at least one additive (A) other than the inorganic filler (F) and the dispersant (D).

2. Polyolefin composition (C) according to any of the preceding claims, wherein the polypropylene (PP) is a heterophasic propylene copolymer.

3. Polyolefin composition (C) according to any of the preceding claims, wherein the polypropylene (PP) has one or more, preferably all of the following properties:

4. Polyolefin composition (C) according to any of the preceding claims, wherein the carbon nanotubes have a molecular weight ranging from 1.8 to 2.1g/cm³A density in the range, and/or a diameter in the range of 2.0 to 25.0nm, and/or a length in the range of 0.1 to 10.0 μm.

5. Polyolefin composition (C) according to any of the preceding claims, wherein the inorganic filler (F) has an average particle size (d) ranging from 0.8 to 40 μm₅₀) Preferably selected from the group comprising talc, calcium carbonate, barium sulfate, mica and mixtures thereof, most preferably the inorganic filler (F) is talc.

6. Polyolefin composition (C) according to any of the preceding claims wherein the dispersant (D) is selected from the group comprising calcium stearate, polyethylene wax, oleamide, erucamide and mixtures thereof, preferably the dispersant (D) is oleamide.

7. Polyolefin composition (C) according to any of the preceding claims, further comprising

8. The polyolefin composition (C) according to claim 7, wherein the Polar Modified Polypropylene (PMP) has a polar group content in the range of 0.5 to 3.0 wt. -%.

9. Polyolefin composition (C) according to any of the preceding claims, wherein the polyolefin composition (C) has a flexural modulus of at least 1800MPa and/or at least 8.0kJ/m²The impact strength of the gap of the simply supported beam.

10. Polyolefin composition (C) according to any of the preceding claims, wherein the polyolefin composition (C) has a maximum of 1000000Ohm/m²The surface resistivity of (a).

11. A process for preparing a polyolefin composition according to any of the preceding claims, comprising the steps of:

b) providing Polypropylene (PP);

d) blending and extruding said polypropylene (PP) with said mixture of additives (A) and dispersants (D) and said blend of Carbon Nanotubes (CNT) and inorganic filler (F) in an extruder, preferably a twin screw extruder, at a temperature in the range of 180 ℃ to 250 ℃.

12. An article, preferably a molded article, most preferably an injection molded article or a foamed injection molded article, comprising more than 75 wt% of the polyolefin composition (C) according to any of claims 1 to 10.

13. The article according to claim 12, wherein the article is part of an automotive article, in particular part of an automotive interior, such as an instrument holder, dashboard, interior trim or the like.

14. Use of a polyolefin composition (C) according to any of claims 1 to 10 for the preparation of automotive articles having improved electromagnetic interference shielding properties.