PLASTIC MATERIAL AND SHAPED ARTICLE OBTAINED THEREFROM

FIELD OF THE INVENTION

[0001] The present disclosure relates to a plastic material and to a shaped article obtainable therefrom.

BACKGROUND OF THE INVENTION

[0002] Future mobility will be based more and more on self-driving or autonomous vehicles. Self-driving vehicles use sensors to perceive their environment and can move safely with little or no human input. The most common sensors are camera or radar based systems. The radar technology has been used for years by car manufacturers to assist with automated cruise control and parking, and the same technology, couple with artificial intelligence, will be used in driverless vehicles soon.

[0003] In a radar system, a transmitter produces electromagnetic waves in the radio- or microwaves frequencies which are transmitted by a transmitting antenna. The transmitted electromagnetic waves are reflected by radar-opaque objects and return to a receiver, providing information on the object’s location and speed, thereby allowing a vehicle to safely move in the environment.

[0004] The electromagnetic frequencies used in radar detection systems used for autonomous driving are at present comprised in the range from 76 GHz to 81 GHz. Use of lower or higher frequencies cannot be excluded in the future.

[0005] In vehicles, radar detection systems are generally embedded in or shielded by exterior trims, in most cases in bumpers. Radar transmission through plastic materials can be hindered by undesired transmission loss, hence plastic materials used to cover radar detection systems should be radar transparent, i.e. should allow the incident electromagnetic waves to pass through the cover with minimal, if at all, attenuation of the incident waves.

[0006] The international patent application W02022/011131 discloses a pigment having an aspect ratio of at least 5 comprising a non-conductive composite comprising a semiconductor and/or a dielectric and a metal dispersed in the semiconductor and/or dielectric, wherein the pigment can be applied as a coating onto plastic objects. [0007] The international patent application W02021/030197 discloses a radar transparent TPO resin coated with a coating system comprising a film-forming resin and a flake pigment composition comprising 50 wt.% or more of a radar transmissive pigment and not more than 50 wt.% of an electrically conductive pigment, wherein the coating system transmits at least 70% of an electromagnetic radiation comprising a frequency from 1 to 100 GHz.

[0008] In this context, there is the need of a plastic material which allows the transmission of electromagnetic waves, including but not limited to radar frequencies, with minimal, if at all, attenuation of the incident waves, said plastic material being suitable for producing shaped articles, in particular a structural part of a shaped article, including but not limited to vehicle bumpers.

SUMMARY OF THE INVENTION

[0009] The present disclosure provides a shaped article comprising a plastic material, the material comprising up to and including 7.0% by weight of inorganic particles (M) comprising a metallic element, and at least 93.0% by weight of a polymer composition (A), wherein the shaped article has thickness d ranging from 0.5 to 20 mm and fulfilling equation (I) when irradiated with an electromagnetic wave of frequency from 1 to 300 GHz wherein

[0010] - d is the thickness of the shaped article;

[0011] - o is the vacuum wavelength corresponding to the frequency of the electromagnetic waves irradiating the shaped article;

[0012] - £ _r is the relative permittivity of the plastic material, and

[0013] - m is an positive whole number equal to or greater than 1, and wherein

[0014] the amounts of (A) and (M) are based on the total weight of the plastic material, the total weight being 100%.

[0015] The present disclosure also provides the use of the shaped article to at least partially cover a device emitting and/or receiving electromagnetic waves, preferably a radar detection system.

[0016] The present disclosure also provides the use of the plastic material to optimize the transmission and/or detection of electromagnetic waves of frequency comprised in the range from 1 to 300 GHz through a shaped article having thickness d ranging from 0.5 to 20 mm. [0017] The plastic material of the present disclosure and the shaped article obtained therefrom allow the transmission of electromagnetic waves, including but not limited to radar frequencies, with minimal, if at all, attenuation of the incident waves.

[0018] Accordingly, the shaped article of the present disclosure may be a cover or a housing for an electromagnetic source and/or detector, such as a radome. The shaped article of the present disclosure may be a part of a vehicle, such as a bumper, shielding an electromagnetic emitting and/or receiving device, such as a radar detection system.

[0019] The mechanical properties of the plastic material of the present disclosure are not substantially influenced by the amount of the inorganic particles (M) comprised in the plastic material.

[0020] While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description. As will be apparent, certain embodiments, as disclosed herein, are capable of modifications in various obvious aspects, all without departing from the spirit and scope of the claims as presented herein. Accordingly, the following detailed description is to be regarded as illustrative in nature and not restrictive.

DETAILED DESCRIPTION OF THE INVENTION

[0021] In the context of the present disclosure;

[0022] - the percentages are expressed by weight, unless otherwise specified;

[0023] - the total weight of a composition sums up to 100%, unless otherwise specified;

[0024] - the term “comprising” referred to a polymer, a plastic material, a polymer composition, mixture or blend, should be construed to mean “comprising or consisting essentially of’;

[0025] - the term “consisting essentially of’ means that, in addition to those components which are mandatory, other components may also be present in a polymer or in a polymer composition, mixture or blend, provided that the essential characteristics of the polymer or of the composition, mixture or blend are not materially affected by their presence. Examples of components that, when present in customary amounts, do not materially affect the characteristics of a polymer or of a polyolefin composition, mixture or blend are catalyst residues and processing aids;

[0026] - the term “copolymer” is referred to a polymer deriving from the polymerization of at least two comonomers, i.e. the term “copolymer” includes bipolymers and terpolymers. [0027] The plastic material preferably comprises or consists of from 0.1 to 7.0% by weight, more preferably from 0.1 to 4.0% by weight, still more preferably from 0.5 to 4.0% by weight, of inorganic particles (M) and from 93.0 to 99.9% by weight, preferably from 96.0 to 99.9% by weight, more preferably from 96.0 to 99.5% by weight, of the polymer composition (A), wherein the amounts of (M) and (A) are based on the total weight of the plastic material, the total weight being 100%.

[0028] In a preferred embodiment, the inorganic particles (M) are dispersed, more preferably uniformly dispersed, in the polymer composition (A), like the inorganic particles (M) are embedded in a matrix consisting of the polymer composition (A).

[0029] In the following the individual components of the plastic material are defined in more detail. The individual components may be comprised in the plastic material in any combination.

[0030] The polymer composition (A) preferably comprises up to and including 100% by weight of at least one polymer (a) selected from the group consisting of propylene polymers (al), ethylene polymers (a2), polybutene-1 (a3), polystyrenes (a4), acrylic polymers (a5), acrylonitrile butadiene styrene polymers (a6), acrylonitrile styrene acrylate polymers (a7), polyamides (a8), polyesters (a9), polyurethanes (alO), polycarbonates (al l) and mixtures thereof, wherein the amount of the polymer (a) is based on the weight of the polymer composition (A), the total weight being 100%.

[0031] In one embodiment, the polymer composition (A) consists of the at least one polymer (a).

[0032] The propylene polymer (al) is preferably selected from the group consisting of: [0033] (al .1) propylene homopolymers;

[0034] (al.2) propylene copolymers with at least one olefin of formula CH2=CHR, where R is hydrogen or a linear or branched C2-C8 alkyl, preferably comprising up to and including 10.0% by weight, more preferably from 0.05% to 10.0% by weight, still more preferably from 0.1% to 8.0% by weight, based on the weight of (al.2), of units deriving from the olefin;

[0035] (al.3) elastomeric propylene copolymers with at least one olefin of formula CH2=CHR, where R is hydrogen or a linear or branched C2-C8 alkyl, preferably comprising up to and including 85% by weight, more preferably from 5% to 85% by weight, still more preferably from 20% to 70% by weight, based on the weight of (al.3), of units deriving from the olefin;

[0036] (al .4) recycled polypropylene (r-PP) which is a waste plastic material derived from post-consumer and/or post-industrial waste; and [0037] (al .5) mixtures thereof.

[0038] In one embodiment, the propylene copolymer (al) is an heterophasic propylene copolymer comprising:

[0039] (1) up to and including 90% by weight, preferably from 10% to 80% by weight, more preferably from 15% to 70% by weight of at least one propylene polymer selected from the group consisting of propylene homopolymers, propylene copolymers with at least one olefin of formula CH2=CHR, where R is hydrogen or a linear or branched C2-C8 alkyl, comprising up to and including 10.0% by weight, preferably from 0.05% to 10.0% by weight, more preferably from 0.1% to 8.0% by weight, based on the weight of (1), of units deriving from the olefin, and mixtures thereof; and

[0040] (2) at least 10% by weight, preferably from 20% to 90% by weight, more preferably from 30% to 85% by weight, of an elastomeric propylene copolymer with at least one olefin of formula CH2=CHR, where R is hydrogen or a linear or branched C2- C8 alkyl, comprising up to and including 85% by weight, more preferably from 20% to 85% by weight, still more preferably from 25% to 75% by weight, based on the weight of (2), of units deriving from the olefin,

[0041] wherein the amounts of (1) and (2) are based on the total weight of (l)+(2).

[0042] In propylene polymers (al) the olefin is preferably selected from the group consisting of ethylene, butene-1, hexene-1, 4-methyl-l -pentene, octene-1 and combinations thereof, ethylene and butene-1 being the most preferred.

[0043] Propylene polymers (al) are commercially available under the trade name Moplen, Hifax, Adstif, Clyrell, Softell, Hiflex marketed by LyondellBasell or Vistamaxx, marketed by Exxon Mobil, eg. Vistamaxx™ 6102.

[0044] The propylene polymers (al) can be obtained by polymerizing the relevant monomers in the presence of a metallocene catalyst system or of a highly stereospecific Ziegler-Natta catalyst systems comprising:

[0045] (1) a solid catalyst component comprising a magnesium halide support on which a

Ti compound having at least a Ti-halogen bond is present, and a stereoregulating internal donor;

[0046] (2) optionally, but preferably, an Al-containing cocatalyst; and

[0047] (3) optionally, but preferably, a further electron-donor compound (external donor).

[0048] The solid catalyst component (1) preferably comprises TiCk in an amount securing the presence of from 0.5 to 10% by weight of Ti with respect to the total weight of the solid catalyst component (1). [0049] The solid catalyst component (1) comprises at least one stereoregulating internal electron donor compound selected from mono or bidentate organic Lewis bases, preferably selected from esters, ketones, amines, amides, carbamates, carbonates, ethers, nitriles, alkoxysilanes and combinations thereof.

[0050] Preferred donors are the esters of phthalic acids such as those described in EP45977A2 and EP395083A2, in particular di-isobutyl phthalate, di-n-butyl phthalate, di-n- octyl phthalate, diphenyl phthalate, benzylbutyl phthalate and combinations thereof.

[0051] Esters of aliphatic acids can also be selected from esters of malonic acids such as those described in WO98/056830, WO98/056833, WO98/056834, esters of glutaric acids such as those disclosed in WO00/55215, and esters of succinic acids such as those disclosed WOOO/63261.

[0052] Particular type of diesters are those deriving from esterification of aliphatic or aromatic diols such as those described in W02010/078494 and USP 7,388,061.

[0053] In some embodiments, the internal donor is selected from 1,3-diethers such as those described in EP361493, EP728769 and W002/100904.

[0054] Specific mixtures of internal donors, in particular of aliphatic or aromatic mono or dicarboxylic acid esters and 1,3-diethers as disclosed in W007/57160 and WO2011/061134 can be used as internal donor.

[0055] Preferred magnesium halide support is magnesium dihalide.

[0056] The amount of internal donor that remains fixed on the solid catalyst component (1) is 5 to 20% by moles, with respect to the magnesium dihalide.

[0057] Preferred methods for the preparation of the solid catalyst component (1) are described in EP395083A2.

[0058] The preparation of catalyst components according to a general method is described for example in European Patent Applications US4,399,054, US4,469,648, W098/44009A1 and EP395083A2.

[0059] In some embodiments, the catalyst system comprises an Al-containing cocatalyst

(2) selected from Al-trialkyls, preferably selected from the group consisting of Al-triethyl, Al- triisobutyl and Al-tri-n-butyl. The Al/Ti weight ratio in the catalyst system is from 1 to 1000, preferably from 20 to 800.

[0060] In embodiments, the catalyst system comprises a further electron donor compound

(3) (external electron donor) selected among silicon compounds, ethers, esters, amines, heterocyclic compounds, particularly 2,2,6,6-tetramethylpiperidine, and ketones. [0061] Preferred silicon compounds are selected among methylcyclohexyldimethoxysilane (C-donor), dicyclopentyldimethoxysilane (D-donor) and mixtures thereof.

[0062] The polymerization process to obtain the propylene polymers (al) may be carried out in continuous or in batch, either in liquid phase or in gas phase.

[0063] The liquid-phase polymerization can be either in slurry, solution or bulk (liquid monomer). This latter technology is the most preferred and can be carried out in various types of reactors such as continuous stirred tank reactors, loop reactors or plug-flow reactors.

[0064] The gas-phase polymerization can be carried out in fluidized or stirred, fixed bed reactors or in a multizone circulating reactor as illustrated in EP 1012195.

[0065] The heterophasic propylene polymers may be obtained by melt blending the components (1) and (2) or, preferably, by polymerizing the relevant monomers either in at least two polymerization stages, wherein the second and each subsequent polymerization stage is carried out in the presence of the polymer produced and the catalyst used in the immediately preceding polymerization stage or in a multizone circulating reactor as disclosed in WO201 1/144489 and WO2018/177701.

[0066] The reaction temperature is preferably comprised in the range from 40°C to 90°C and the polymerization pressure is preferably from 3.3 to 4.3 MPa for a process in liquid phase and from 0.5 to 3.0 MPa for a process in the gas phase.

[0067] The ethylene polymers (a2) are preferably selected from the group consisting of: [0068] (a2.1) thermoplastic ethylene polymers, such as ultra-high molecular weight polyethylene (UHMWPE), high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE);

[0069] (a2.2) elastomeric ethylene copolymers with at least one alpha-olefin of formula

CH2=CHR ¹ , wherein R ¹ is a linear or branched C1-C8 alkyl, preferably comprising at least 20% by weight, more preferably from 20% to 50% by weight, based on the weight of (a2.2), of units deriving from the alpha-olefin;

[0070] (a2.3) recycled polyethylene (r-PE) which is a waste plastic material derived from post-consumer and/or post-industrial waste; and [0071] (a2.4) mixtures thereof.

[0072] In ethylene polymers (a2), the alpha-olefin is preferably selected from propylene, butene- 1, hexene- 1, octene- 1 and combinations thereof.

[0073] Ethylene polymers (a2.1) are commercially available, for example under the trade name Alathon, Lucalen and Luflexen marketed by LyondellBasell and can be prepared by known polymerization processes using Ziegler or Phillips catalysts, either in solution or in gas phase.

[0074] Ethylene polymers (a2.2) are commercially available, for example under the tradename of Engage, eg. Engage™ 8100 or Engage™ 8150, marketed by Dow®, and can be obtained by known polymerization processes making use of metallocene-based catalyst systems.

[0075] Polybutene- 1 (a3) is preferably selected from the group consisting of butene- 1 homopolymers, butene- 1 copolymers with at least one olefin selected from the group consisting of ethylene and CH2=CHR ² alpha-olefins, wherein R ² is methyl or a linear or branched C3-C8 alkyl, and combinations thereof.

[0076] Ethylene and propylene are the preferred comonomers in butene- 1 copolymers (a3). Preferably, ethylene and/or the alpha-olefin is comprised in butene- 1 copolymers (a3) in a range from 0.1% to 20% by weight, based on the weight of the butene-1 copolymer (a3).

[0077] Butene-1 polymers (a3) are available on the market, for example under the trade name Koattro marketed by LyondellBasell, and can be produced by known polymerization processes making use of Ziegler-Natta or metallocene-based catalyst systems, generally using solution polymerization.

[0078] Polystyrenes (a4) are preferably selected from thermoplastic homopolymers of styrene or of alpha-methylstyrene (a4.1), saturated or unsaturated styrene or alphamethylstyrene block copolymers (a4.2), preferably comprising up to and including 30% by weight of polystyrene, more preferably from 10% to 30% by weight, based on the weight of (a4.2), recycled styrene block copolymers (r-SBC) which are waste plastic materials derived from post-consumer and/or post-industrial waste (a4.3); and mixtures thereof.

[0079] The saturated or unsaturated styrene or alpha-methylstyrene block copolymer (a4.2) is preferably selected from the group consisting of polystyrene-polybutadiene-polystyrene (SBS), poly styrene-poly(ethylene-butylene)-poly styrene (SEBS), polystyrene-poly(ethylene- propylene)-polystyrene (SEPS), polystyrene-polyisoprene-polystyrene (SIS), polystyrene- poly(isoprene-butadiene)-poly styrene (SIBS) and mixtures thereof.

[0080] Styrene and alpha-methylstyrene block copolymers (a4.2) are prepared by ionic polymerization of the relevant monomers and are commercially available under the tradename of Kraton™ marketed by Kraton Polymers.

[0081] Acrylic polymers (a5) are preferably selected from the group consisting of poly(methacrylate) (PMA), poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), poly(2 -hydroxyethyl methacrylate) (poly-HEMA) and mixtures thereof. [0082] Polyamides (a8) are preferably selected from aliphatic polyamides, polyphthalamides, aromatic polyamides, polyamide-imide and mixtures thereof.

[0083] Among aliphatic polyamides, nylon PA6 and nylon PA66 are the most preferred.

[0084] Polyamides (a8) are commercially available and can be produced by condensation polymerization processes well known in the art.

[0085] Polyesters (a9) are preferably selected from the group consisting of polyethylene terephthalate (PET), glycol-modified polyethylene terephthalate (PETG), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL) and mixtures thereof.

[0086] The polymer (a) optionally comprises customary amounts, preferably up to and including 5.0% by weight, more preferably from 0.01% to 5.0% by weight, based on the total weight of the polymer (a), the total weight being 100%, of at least one additive selected from the group consisting of nucleating agents, antistatic agents, anti-oxidants, light stabilizers, slipping agents, anti-acids, melt stabilizers, and combinations thereof.

[0087] In one embodiment, the polymer composition (A) comprises up to and including 50% by weight, preferably from 2 to 50% by weight, of at least one further component (b) selected from the group consisting of fillers, pigments, flame retardants, compatibilizers and combinations thereof, wherein the amounts of (a) and (b) are based on the total weight of the polymer composition (A), the total weight being 100%.

[0088] The filler is preferably selected from the group consisting of mineral fillers, preferably talc, mica, glass fibers, glass beads, carbon fibers, carbon black, natural fibers, carbon nanotubes, fullerenes and combinations thereof.

[0089] Pigments and flame retardants are of the type used in the field of polyolefins.

[0090] The compatibilizer is preferably a modified olefin polymer, preferably polypropylene and/or polyethylene, functionalized with polar compounds. The modified olefin polymers are selected from graft copolymers, block copolymers and mixtures thereof. Preferably, the compatibilizer is a polyolefin, more preferably selected from polyethylenes, polypropylenes and mixtures thereof, functionalized with a compound selected from the group consisting of maleic anhydride, C1-C10 linear or branched dialkyl maleates, C1-C10 linear or branched dialkyl fumarates, itaconic anhydride, Cl -CIO linear or branched itaconic acid, dialkyl esters, maleic acid, fumaric acid, itaconic acid and mixtures thereof. In a preferred embodiment, the compatibilizer is a polyethylene and/or a polypropylene grafted with maleic anhydride (MAH-g-PP and/or MAH-g-PE). [0091] Examples of modified polyolefins suitable for use as compatibilizer are the commercial products Amplify™ TY by The Dow Chemical Company, Exxelor™ by ExxonMobil Chemical Company, Scona® TPPP by Byk (Altana Group), Bondyram® by Polyram Group and Polybond® by Chemtura and combinations thereof. Modified polymers can be produced by functionalization processes carried out in solution, in the solid state or preferably in the molten state, eg. by reactive extrusion of the polymer in the presence of the grafting compound and of a free radical initiator. Functionalization of polypropylene and/or polyethylene with maleic anhydride is described for instance in EP0572028A1.

[0092] Preferably the polymer composition (A) comprises or consists of:

[0093] - up to and including 100% by weight, preferably from 50% to 98% by weight, of the polymer (a) according to any one of the embodiments described above, and

[0094] - up to and including 50% by weight, preferably from 2% to 50% by weight, of a component (b) selected from the group consisting of fillers, pigments, flame retardants and combinations thereof,

[0095] wherein the amounts of (a) and (b) are based on the total weight of the polymer composition (A), the total weight being 100%.

[0096] The metallic element comprised in the inorganic particles (M) is preferably selected from the group consisting of magnesium, calcium, strontium, barium, aluminum, titanium, vanadium, chromium, iron, copper, zinc, ruthenium, rhodium, palladium, silver, tin, platinum, gold, titanium, zirconium, alloys of said metals and combinations thereof, aluminum being particularly preferred.

[0097] The inorganic particles (M) preferably comprise or consist of metal particles, particles of inorganic compounds and mixtures thereof.

[0098] Metal particles preferably consist of at least one metal described above or at least one of their alloys, and are preferably in the form of metal flakes. Aluminum flakes are particularly preferred.

[0099] Inorganic compounds are preferably selected from metal oxides and mixed metal oxides, eg. AI2O3, TiCh, titanate and zirconates of the metals described above, eg. BaTiCh, Ca2ZrO4, ceramic particles comprising the metals described above, zeolites, and combinations thereof.

[0100] The inorganic particles (M) preferably have an average particle size D50 equal to or lower than 200 microns, more preferably equal to or lower than 150 microns, more preferably equal to or lower than 100 microns. In one embodiment, the lower limit for the average particle size is 1 micron for all the upper limits above. [0101] Preferably the inorganic particles (M) also have particle size equal to or greater than 0.2 microns.

[0102] The plastic material is obtained by dry blending or, preferably, by melt blending the polymer composition (A) and the inorganic particles (M) in a conventional melt blending equipment, preferably in a twin-screw extruder, by feeding them sequentially or simultaneously to the equipment.

[0103] In one embodiment, the polyolefin composition (A) comprises a polymer (a) and further component (b). The polymer (a) and the further component (b) can be dry blended or, preferably, mixed in a melt blending equipment prior to the melt blending of the polyolefin composition (A) with the inorganic particles (M) to obtain the plastic material. Alternatively the polymer (a), the further component (b) and the inorganic particles (M) are dry blended or preferably, fed separately to the melt blending equipment to obtain the plastic material.

[0104] The presence of the inorganic particles (M) into the plastic material in amount of up to and including 7% by weight has a limited influence on the mechanical property of the polymer composition (A), and the mechanical properties of the plastic material do not significantly differ from the mechanical properties of the polymer composition (A) to which no inorganic particles (M) are not added.

[0105] The plastic material of the present disclosure is suitable for forming a shaped article, preferably the structural part of a shaped article.

[0106] The shaped article of the present disclosure is obtained/obtainable by known processes to shape plastic materials, preferably by injection molding.

[0107] In one embodiment, the shaped article of the present disclosure is obtained or obtainable by shaping, preferably by injection molding, a plastic material as described above.

[0108] The shaped article has thickness d fulfilling the following equation (I) when the shaped article is irradiated with an electromagnetic wave of frequency from 1 to 300 GHz, preferably with an electromagnetic wave of frequency comprised in the range from 70 to 130 GHz, more preferably from 76 to 81 GHz:

[0109] wherein

[0110] - d is the thickness of the shaped article, measured at the point of the incident electromagnetic wave;

[OHl] - Ao is the vacuum wavelength corresponding to the frequency of the electromagnetic waves irradiating the shaped article; [0112] - £ _r is the relative permittivity of the plastic material determined as described in the experimental section, and

[0113] - m is an positive whole number equal to or greater than 1.

[0114] The thickness d of the shaped article ranges from 0.5 to 20 mm, preferably from 0.5 to 15 mm, more preferably from 1 to 10 mm.

[0115] The ko is a known numeric value determined by the radiation with which the shaped article is irradiated.

[0116] Preferably m is a whole number ranging from 1 to 20, preferably from 1 to 16, more preferably from 1 to 10, still more preferably from 1 to 6.

[0117] The shaped article of the present disclosure allows the transmission of electromagnetic waves, including but not limited to radar frequencies, with minimal, if at all, attenuation of the incident waves.

[0118] In a preferred embodiment, the shaped article is a vehicle bumper, a cover or a housing for a device emitting and/or receiving electromagnetic waves, such as a radome.

[0119] The shaped article of the present disclosure is suitable for use to at least partially, preferably completely, cover a device emitting and/or receiving electromagnetic waves, such as a radar detection system of an autonomous driving vehicle.

[0120] Accordingly, the present disclosure also refers to a device configured to emit and/or receive electromagnetic waves at least partially, preferably completely, covered by the shaped article as described above. In a preferred embodiment, the device is a radar detection system of an autonomous driving vehicle.

[0121] The present disclosure also provides the use of a plastic material comprising up to and including 7% by weight, preferably from 0.05 to 7.0% by weight, of inorganic particles (M) comprising a metallic element, and at least 93.0% by weight, preferably from 93.0 to 99.95 % by weight, of a polymer composition (A), wherein the amounts of (A) and (M) are based on the weight the plastic material, the total weight being 100%, to optimize the transmission of electromagnetic waves of frequency comprised in the range from 1 to 300 GHz through a shaped article having thickness d ranging from 0.5 to 20 mm.

[0122] The use according to the present disclosure comprises shaping, preferably by injection molding, the plastic material into an article having thickness d fulfilling the equation (I), wherein the values of d, Ao, s _r and m are as defined above.

[0123] The present disclosure also provides a method to optimize the transmission of electromagnetic waves of frequency comprised in the range from 1 to 300 GHz though a shaped article, the method comprising: [0124] - providing a plastic material comprising up to and including 7% by weight, preferably from 0.05 to 7.0% by weight, of inorganic particles (M) comprising a metallic element, and at least 93.0% by weight, preferably from 93.0 to 99.95 % by weight, of a polymer composition (A), wherein the amounts of (A) and (M) are based on the weight the plastic material, the total weight being 100%; and

[0125] - shaping the plastic material into an article with a thickness d ranging from 0.5 to

20 mm and fulfilling the following equation

[0126] wherein

[0127] d is the thickness of the shaped article;

[0128] ko is the vacuum wavelength corresponding to the frequency of the electromagnetic waves irradiating the shaped article, the frequency ranging from 1 to 300 GHz;

[0129] £r is the relative permittivity of the plastic material, and

[0130] m is an positive whole number equal to or greater than 1.

[0131] The composition of the plastic material and the values of <7, Ao, s _r and m are as described above.

[0132] The optimization of the transmission of electromagnetic waves through the shaped article results in an optimized emission and/or detection of the waves by an emitting and/or detecting device shielded by the shaped article, such as the radar detection system of an autonomous vehicle.

[0133] The features describing the subject matter of the present disclosure are not inextricably linked to each other. Hence, preferred ranges of one feature may be combined with more or less preferred ranges of a different feature, independently from their level of preference.

[0134] EXAMPLES

[0135] The following examples are illustrative only, and are not intended to limit the scope of the disclosure in any manner whatsoever.

[0136] CHARACTERIZATION METHODS

[0137] The following methods are used to determine the properties indicated in the description, claims and examples.

[0138] Melt Flow Rate: Determined according to the method ISO 1133 (230°C, 2.16Kg for the thermoplastic polyolefins; 190°C/2.16Kg for the compatibilizer). [0139] Solubility in xylene at 25°C: 2.5 g of polymer sample and 250 ml of xylene are introduced in a glass flask equipped with a refrigerator and a magnetic stirrer. The temperature is raised in 30 minutes up to 135°C. The obtained clear solution is kept under reflux and stirring for further 30 minutes. The solution is cooled in two stages. In the first stage, the temperature is lowered to 100°C in air for 10 to 15 minute under stirring. In the second stage, the flask is transferred to a thermostatically controlled water bath at 25°C for 30 minutes. The temperature is lowered to 25°C without stirring during the first 20 minutes and maintained at 25°C with stirring for the last 10 minutes. The formed solid is filtered on quick filtering paper (eg. Whatman filtering paper grade 4 or 541). 100 ml of the filtered solution (SI) is poured in a previously weighed aluminum container, which is heated to 140°C on a heating plate under nitrogen flow, to remove the solvent by evaporation. The container is then kept on an oven at 80°C under vacuum until constant weight is reached. The amount of polymer soluble in xylene at 25°C is then calculated. XS(I) and XSA values are experimentally determined. The fraction of component (B) soluble in xylene at 25°C (XSB) can be calculated from the formula:

XS = W(A)X(XSA) + W(B)X(XSB) wherein W(A) and W(B) are the relative amounts of components (A) and (B), respectively, and W(A)+ W(B)=1.

[0140] C2 content in propylene-ethylene copolymer (II): ¹³ C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cry oprobe, operating at 160.91 MHz in the Fourier transform mode at 120°C. The peak of the Ppp carbon (nomenclature according to C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 10, 3, 536 (1977)) was used as internal reference at 2.8 ppm. The samples were dissolved in 1, 1,2,2-tetrachloroethane- d2 at 120°C with a 8 % wt/v concentration. Each spectrum was acquired with a 90° pulse, 15 seconds of delay between pulses and CPD to remove ^J H- ¹³ C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz. The assignments of the spectra, the evaluation of triad distribution and the composition were made according to Kakugo [M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 16, 4, 1160 (1982)]. Owing to the low amount of Propylene inserted as regioirregular units, ethylene content was calculated according to Kakugo [M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 16, 4, 1160 (1982)] using only triad sequences with P inserted as regular unit.

[0141] PPP = 100 Tpp/S

[0142] PPE = 100 T _ps /S [0143] EPE = 1OO T ₅₅ /S

[0144] PEP = 100 Spp/S

[0145] PEE= 100 Sp ₅ /S

[0146] EEE = 100 (0.25 S _Y8 +0.5 S ₈₈ )/S

[0147] Where S = Tpp + Tp ₈ + T ₈₈ + Spp + Sp ₈ + 0.25 S _Y8 + 0.5 S ₈₈

[0148] The molar content of ethylene and propylene is calculated from triads using the following equations:

[Ejmol = EEE + PEE + PEP

[P]moZ = PPP + PPE + EPE

[0149] The weight percentage of ethylene content (E% wt) is calculated using the following equation: wherein

[P] mol = the molar percentage of propylene content;

MWE = molecular weights of ethylene

MWP = molecular weight of propylene.

[0150] The total ethylene content C2(tot) and the ethylene content of component (A), C2(A), are measured; the ethylene content of component (B), C2(B), is calculated using the formula:

C2(tot) = W(A)xC2(A) + W(B)xC2(B) wherein W(A) and W(B) are the relative amounts of components (A) and (B) (W(A)+W(B)=1). [0151] Flexural Modulus: determined according to ISO 178/A:2019-04 on injection molded specimens Type 1 according to ISO 20753.

[0152] Relative permittivity s _r and attenuation: The relative permittivity is measured with a Radome Measurement System RMS-D-77/79G from perisens GmbH performing a free space transmission (S21) measurement in amplitude and phase which is used to determine the relative permittivity of materials in the frequency range between 76 and 81 GHz. The equipment sends radar waves with a given frequency band through the material sample. The damp of the signal is calculated with one measurement without a sample followed by a measurement with the sample. To calculate the permittivity, the damp between both measurements and the thickness of the sample (measured with an Mitutoyo digital sheet metal micrometer IP65) are used. [0153] Particle size and particle size distribution: measured by laser diffraction, eg. using a Mastersizer Hydro 3000 (15 sec. testing, stirring speed 3500 rpm).

[0154] RAW MATERIALS:

[0155] HECO: an heterophasic polyolefin composition comprising 60 wt.% of propylene homopolymers (1) and 40 wt.% of a propylene-ethylene copolymer (1) containing 68 wt.% of ethylene, based on the weight of the copolymer (b), wherein the amounts of (a) and (b) are based on the total weight of the HECO. The HECO is a reactor-blend of components (a) and (b) obtained as described in examples 1-2 of the patent application W02005/014715A1.

[0156] Talc: Jetfine® 3 C A marketed by Imerys Performance Additives.

[0157] Inorganic particles (M): Pellex A32-30LW marketed by Metaflake Ltd., a pellet containing 30% by weight of polyethylene wax and 70% by weight of aluminum flakes having average particle size D50 of 32 microns.

[0158] Comparative examples CE1-CE2 and example E3

[0159] A plastic material having the composition of table 1 was prepared by compounding in a two screw extruder operated at 300 rpm, with an mass flow of 40 kg/h at 220°C (zone 1=200 °C, zone 2=210 °C, zone3=220 °C, zone 3=zone 4=zone 5=zone 6). The article was obtained by shaping the plastic materials having the composition of table 1 into 2.42 mm-thick plaques using an injection molding machine with a clamping force of 1600 kN and a screw diameter of 50 mm. The extruder was operated in the following conditions:

[0160] melt temperature: 225°C;

[0161] mould temperature: 30°C;

[0162] average injection velocity: 100 mm/s;

[0163] cavity pressure change-over point: 150 bar;

[0164] holding pressure (hydraulic): 50 bar;

[0165] holding pressure time: 30 s;

[0166] Cooling time: 28 s.

[0167] The test specimens were irradiated with a radar frequency of 77 GHz (corresponding to a To vacuum wavelength of 3.89 mm) and the equation (I) was satisfied for m=2. The value of the relative permittivity sr was experimentally determined.

[0168] The compositions of the plastic materials and the tested properties of the shaped articles are reported in table 1. Table 1