POLYPROPYLENE COMPOSITION AND LIGHT-SOURCE COVERING MADE

THEREFROM

FIELD OF THE INVENTION

[0001] The present disclosure relates to a propylene polymer composition and to a light-source cover obtainable therefrom.

BACKGROUND OF THE INVENTION

[0002] Glass-filled polyolefins are widely used in the automotive field for the injection molding of interior and exterior parts. Glass-filled polyolefins have several advantageous properties such as high strength and stiffness.

[0003] However, soft-touch materials are preferred for car interiors, to increase the tactile appeal of surfaces and create the feeling of a living room inside the car.

[0004] Filled polyolefin compositions for injection molding having a good balance between strength and toughness are known in the art.

[0005] US Patent 5,916,953 discloses a tough, strong, stiff glass-filled polyolefin composition comprising a highly isotactic propylene polymer, glass fibers, a plastomer copolymer of ethylene with a C4-C6 alpha-olefin and a compatibilizer.

[0006] The patent application US2016/0160017 discloses how the mixing of a low molecular weight atactic polypropylene and of an ultra-high molecular weight polypropylene to a polyolefin composition comprising an isotactic polypropylene base resin, an inorganic filler and a rubber improves the composition’s mechanical properties, fluidity and impact strength.

[0007] The patent application W02007/025663 discloses molding composition having a pleasant soft-touch feel, high stiffness and good scratch resistance comprising a combination of a soft material, a glass material as filler and a thermoplastic propylene polymer.

[0008] Beside mechanical properties, optical properties of plastics are also relevant in the automotive field since original equipment manufacturers tend to create new cars with a futuristic interior and exterior design, eg. light bars or light spots covered with plastic material. For backlighted parts polymethylmethacrylate (PMMA) or polycarbonate (PC) are mainly used. [0009] In this context, there is the need of a plastic material having a good balance of mechanical properties, in particular of impact and stiffness, and suitable optical properties for use in manufacturing articles that can be backlighted allowing the light to pass through them.

SUMMARY OF THE INVENTION

[0010] The present disclosure provides a covering for a light-source comprising a polyolefin composition comprising:

[0011] (A) 50-80% by weight, of a propylene polymer comprising up to and including 40% by weight, based on the weight of (A), of units deriving from ethylene and/or at least one alpha- olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl;

[0012] (B) 15-35% by weight of an elastomeric component selected from the group consisting of:

(Bl) ethylene copolymers with at least one alpha-olefin of formula CH2=CHR ² , where R ² is a linear or branched C1-C8 alkyl;

(B2) saturated or unsaturated styrene or alpha-methylstyrene block copolymers, and (B3) combinations thereof;

[0013] (C) 5-30% by weight of glass fibers, and

[0014] (D) 0-5.0% by weight of a compatibilizer,

[0015] wherein the amount of (A), (B), (C) and (D) is based on the total weight of (A)+(B)+(C)+(D), the total weight being 100%.

[0016] The present disclosure further provides the use of the polyolefin composition as covering for a light-source and a process for manufacturing a covering for a light-source comprising the use of the polyolefin composition as described above.

[0017] The polyolefin composition of the present disclosure is translucent and has low absorbance in the visible region of the light spectrum. These properties render the composition suitable for use in manufacturing articles which can be backlighted letting the light pass through without seeing the light source behind, such as a covering for a light-source. [0018] Moreover, the absorbance does not change significantly throughout the visible light spectrum, thereby allowing light of different colors to be transmitted through the article substantially with the same intensity.

[0019] The polyolefin composition of the present disclosure is also endowed with a good balance of mechanical properties, in particular flexural modulus and impact, in combination with low shrinkage. It is therefore suitable for manufacturing light-source coverings having both aesthetic and structural function.

[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.

DESCRIPRION OF THE DRAWING

[0021] FIG. 1 provides a plot of the absorbance values measured on lOOpm-thick films having the compositions of comparative examples CE11 and CE12 and of the examples El 3-El 5 according to the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0022] In the context of the present disclosure;

[0023] - the percentages are expressed by weight, unless otherwise specified;

[0024] - when the term “comprising” is referred to a polymer or to a polymer composition, mixture or blend, it 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, antistatic agents, melt stabilizers, light stabilizers, antioxidants and antiacids.

[0026] The polyolefin composition comprises: [0027] 50-80% by weight, preferably 55-75% by weight, more preferably 60-70% by weight of the propylene polymer (A);

[0028] 15-35% by weight, preferably 15-30% by weight, more preferably 20-23% by weight of the elastomeric component (B);

[0029] 5-30% by weight, preferably 5-25% by weight, more preferably 7-20% by weight of the glass fibers (C);

[0030] 0.15-5.0% by weight, more preferably 0.20-3.0% by weight of the compatibilizer,

[0031] wherein the amounts of (A), (B) (C) and (D) are based on the total weight of (A)+(B)+(C)+(D), the total weight being 100%.

[0032] In the polyolefin composition of the instant disclosure components (A), (B), (C) and optionally (D) are preferably selected from the components described below, which can be comprised in the composition in any combination.

[0033] The propylene polymer (A) can be a propylene random copolymer, a polyolefin composition comprising a propylene random copolymer or an heterophasic propylene polymer comprising a crystalline or semi-crystalline matrix phase and a rubbery phase dispersed therein. [0034] In all embodiments described below, R ¹ is preferably an alkyl selected from the group consisting of butene- 1, hexene- 1, 4-methyl- 1-pentene, octene-1 and combinations thereof, preferably butene- 1.

[0035] The propylene polymer (A) is preferably selected from the group consisting of:

(Al) propylene copolymers with ethylene and/or at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, the copolymer comprising up to and including 8.5% by weight, preferably from 0.1 to 8.5% by weight, based on the weight of (Al), of units deriving from ethylene and/or the alpha-olefin;

(A2) polypropylene compositions comprising:

(A2.1) 25-65% by weight of a propylene homopolymer or a propylene copolymer with ethylene and/or at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, the copolymer comprising up to and including 2% by weight, preferably from 0.1 to 2% by weight, based on the weight of (A2.1), of units deriving from ethylene and/or the alpha-olefin; and

(A2.2) 35-75% by weight of a propylene copolymer with ethylene and/or at least one alpha- olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, the copolymer comprising up to and including 15% by weight, preferably from 0.1 to 15% by weight, based on the weight of (A2.2), of units deriving from ethylene and/or the alpha-olefin, wherein the amounts of (A2.1) and (A2.2) are based on the total weight of (A2.1)+(A2.2), the total weight being 100%;

(A3) polypropylene compositions comprising:

(A3.1) 55-80% of a propylene polymer selected from the group consisting of propylene homopolymers, propylene copolymers with ethylene and/or at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, and mixtures thereof, the copolymer comprising up to and including 10% by weight, preferably from 0.1 to 10% by weight, based on the weight of (A3.1), of units deriving from ethylene and/or the alpha- olefin;

(A3.2) 20-45% by weight of a copolymer of propylene with ethylene and/or at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, and mixtures thereof, the propylene copolymer comprising up to and including 40% by weight, preferably from 15 to 40% by weight, based on the weight of (A3.2), of units deriving from ethylene and/or the alpha-olefin, wherein the polypropylene composition (A3) comprises up to and including 40% by weight, preferably from 0.1 to 40% by weight, based on the weight of (A3), of units deriving from ethylene and/or the alpha-olefin and the amounts of (A3.1) and (A3.2) are based on the total weight of (A3.1)+(A3.2), the total weight being 100%;

(A4) polypropylene compositions comprising:

(A4.1) 55-80% of a propylene polymer selected from the group consisting of propylene homopolymers, propylene copolymers with ethylene and/or at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, and mixtures thereof, the copolymer comprising up to and including 10% by weight, preferably from 0.1 to 10% by weight, based on the weight of (A4.1), of units deriving from ethylene and/or the alpha- olefin;

(A4.2) 20-45% by weight of a copolymer of ethylene with at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, and mixtures thereof, the ethylene copolymer comprising up to and including 40% by weight, preferably from 10 to 40% by weight, based on the weight of (A4.2), of units deriving from the alpha-olefin, wherein the polypropylene composition (A4) comprises a total amount of up to and including 40% by weight, preferably from 0.1 to 40% by weight, based on the weight of (A4), of units deriving from ethylene and the alpha-olefin and the amounts of (A4.1) and (A4.2) are based on the total weight of (A4.1)+(A4.2), the total weight being 100%;

(A5) mixtures thereof.

[0036] In one preferred embodiment, propylene copolymer (Al) is selected from propylene- ethy lene- butene- 1 terpolymers (Ala) comprising from 0.5 to 1.8% by weight, preferably from 0.7 to 1.5% by weight, more preferably from 0.9 to 1.3% by weight, based on the weight of component (Ala), of units deriving from ethylene and from 3.5 to 6.5% by weight, preferably from 4.5 to 6.0% by weight, more preferably from 4.8 to 5.8% by weight, based on the weight of the (Ala) of units deriving from butene- 1.

[0037] More preferably, the propylene terpolymer (Ala) has at least one of the following properties:

[0038] - a total amount of units deriving from ethylene and butene- 1 ranging from 5.5 to 7.5% by weight, preferably from 5.7 to 7.1% by weight, based on the weight of (Ala); and/or [0039] - a xylene soluble fraction lower than 7.0% by weight, more preferably lower than 5.5% by weight, based on the weight of (Ala); and/or

[0040] - a melting point equal to or higher than 140°C, more preferably from 140°C to 152°C.

[0041] In a further preferred embodiment, the propylene terpolymer (Ala) is endowed with all the properties above.

[0042] In one embodiment, the polymeric chain of the propylene terpolymer (Ala) consists of units deriving from propylene, ethylene and butene- 1, wherein the propylene terpolymer has all the properties above.

[0043] The propylene polymers (Al ), including the propylene terpolymers (Ala), are available on the market and can be obtained by polymerizing the relevant monomers in the presence a highly stereospecific Ziegler-Natta catalyst systems comprising:

[0044] (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;

[0045] (2) optionally, but preferably, an Al-containing cocatalyst; and

[0046] (3) optionally, but preferably, a further electron-donor compound (external donor). [0047] The solid catalyst component (1) preferably comprises TiCL 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).

[0048] 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.

[0049] Preferred donors are the esters of phthalic acids such as those described in EP45977A2 and EP395083 A2, in particular di-isobutyl phthalate, di-n- butyl phthalate, di-n-octyl phthalate, diphenyl phthalate, benzylbutyl phthalate and combinations thereof.

[0050] 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. [0051] 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.

[0052] In some embodiments, the internal donor is selected from 1,3-diethers such as those described in EP361493, EP728769 and WO02/100904.

[0053] 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.

[0054] Preferred magnesium halide support is magnesium dihalide.

[0055] 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.

[0056] Preferred methods for the preparation of the solid catalyst component (1) are described in EP395083 A2.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Preferred silicon compounds are selected among methylcyclohexyldimethoxysilane (C-donor), dicyclopentyldimethoxysilane (D-donor) and mixtures thereof.

[0061] The propylene copolymer (Al) is preferably produced with a polymerization process and reactor illustrated in the European patent EP1012195B1. This polymerization process is carried out in a gas-phase reactor, called multizone circulating reactor (MZCR), having two interconnected polymerization zones. The polymer particles flow upwards through a first polymerization zone, denominated “riser”, under fast fluidization or transport conditions, leave said riser and enter a second polymerization zone, denominated “downcomer”, through which they flow in a densified form under the action of gravity. A continuous circulation of polymer is established between the riser and the downcomer. Generally, a condition of fast fluidization is established in the riser by feeding a gas mixture comprising the relevant monomers to the riser. The catalyst system is preferably fed to the reactor at any point of the riser.

[0062] In a multizone circulating reactor is possible to obtain two polymerization zones with different composition by feeding a gas/liquid stream (barrier stream) to the upper part of the downcomer. The gas/liquid stream acts as a barrier to the gas phase coming from the riser, and is capable to establish a net gas flow upward in the upper portion of the downcomer. The established flow of gas upward has the effect of preventing the gas mixture present in the riser from entering the downcomer.

[0063] The molecular weight of the propylene copolymers is regulated using chain transfer agents, such as hydrogen or ZnEt2.

[0064] A multizone circulating reactor is generally operated at a temperature of 50-120°C, preferably of 70°-90°C, and at pressures of 0.5-10 MPa, preferably of 1.5-6 MPa.

[0065] The polypropylene composition (A2) is a blend, either an extruder or, preferably, a reactor blend, of propylene polymers (A2.1) and (A2.2). In a preferred embodiment the propylene polymer (A2.1) is a propylene homopolymer and propylene polymer (A2.2) is a random propylene-ethylene copolymer. [0066] Preferably the polypropylene composition (A2) has at least one of the following properties:

[0067] - comprises a total amount of units deriving from ethylene and/or the alpha-olefin, preferably exclusively from ethylene, between 1 and 10% by weight, more preferably between 2 and 5% by weight, based on the weight of (A2); and/or

[0068] - has a xylene soluble fraction lower than 10% by weight, preferably lower than 7% by weight, based on the weight of (A2).

[0069] In a further preferred embodiment, the polyolefin composition is endowed with all the properties above.

[0070] The polypropylene compositions (A2) are available on the market and can be obtained by melt blending component (A2.1) and component (A2.2) or, preferably, by polymerizing the relevant monomers 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.

[0071] The monomers are polymerized in the presence of a catalyst selected from metallocene compounds, highly stereospecific Ziegler-Natta catalyst systems as described above and combinations thereof, preferably in the presence of a highly stereospecific Ziegler-Natta catalyst system.

[0072] The polymerization to obtain the single components ( A2.1 ) and (A2.2) or the sequential polymerization process to obtain the polypropylene composition (A2) can be carried out in continuous or in batch, either in liquid phase or in gas phase.

[0073] 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.

[0074] The gas-phase polymerization can be carried out in fluidized or stirred, fixed bed reactors or in a multizone circulating reactor as illustrated in EP1012195.

[0075] The reaction temperature is preferably comprised in the range from 40°C to 90°C and the polymerization pressure is 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. [0076] The polypropylene composition (A3) is a blend, either an extruder or, preferably, a reactor blend, of a crystalline or semi-crystalline propylene polymer matrix (A3.1) and a rubbery propylene copolymer (A3.2).

[0077] The polypropylene composition (A4) is a blend, either an extruder or, preferably, a reactor blend, of a crystalline or semi-crystalline propylene polymer matrix (A4.1) and a rubbery ethylene/alpha-olefin copolymer (A4.2).

[0078] In a preferred embodiment, the polypropylene composition (A4) is a polyolefin composition (A4a) comprising:

(A4.1a) 55-80% by weight of a propylene polymer selected from the group consisting of propylene homopolymers, propylene copolymers with ethylene and/or at least one alpha- olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, and mixtures thereof, the copolymer comprising up to and including 10% by weight, preferably from 0.1 to 10% by weight, based on the weight of (A4.1a), of units deriving from ethylene and/or the alpha-olefin, wherein the propylene polymer (A4.1a) has a melt flow rate measured according to ISO 1133 (230°C, 2.16 kg) equal to or higher than 15 g/10 min., preferably from 15 g/10 min. to 80 g/10. min., more preferably from 20 g/10 min. to 60 g/10 min.; and

(A4.2a) 20-45% by weight of a copolymer of ethylene with at least one alpha-olefin of formula CH2=CHR ¹ , where R ¹ is a linear or branched C2-C8 alkyl, preferably butene- 1, wherein the ethylene copolymer comprises up to and including 40% by weight, preferably from 10 to 40% by weight, based on the weight of (A4.2a), of units deriving from the alpha- olefin; wherein the polypropylene composition (A4a) comprises a total amount of up to and including 40% by weight, preferably from 0.1 to 40% by weight, based on the weight of (A4a), of units deriving from ethylene and the alpha-olefin and the amounts of (A4.1a) and (A4.2a) are based on the total weight of (A4.1a)+(A4.2a), the total weight being 100%.

[0079] Preferably, the polyolefin composition (A4a) comprises 60-80% by weight, more preferably 60-75% by weight, of the propylene polymer (A4.1a) and 20-40% by weight, more preferably 25-40% by weight, of the copolymer of ethylene (A4.2a), wherein the amounts of (A4. la) and (A4.2a) are based on the total weight of (A4. la)+(A4.2a), the total weight being 100%. [0080] In a preferred embodiment, the polyolefin composition (A4a) has at least one of the following properties:

[0081] - a xylene soluble fraction from 15% to 35% by weight, preferably from 18% to 35% by weight, more preferably from 18% to 30% by weight, based on the weight of (A4a); and/or [0082] - an intrinsic viscosity of the xylene soluble fraction equal to or lower than 1.7 dl/g, preferably from 0.8 to 1.7 dl/g, more preferably from 1.0 to 1.6 dl/g.

[0083] In a particularly preferred embodiment, the polyolefin composition (A4a) is endowed with all the properties above.

[0084] In a further preferred embodiment, the polypropylene composition (A4a) comprises:

(A4. la) 55-80% by weight, preferably 60-80% by weight, more preferably 60-75% by weight of a propylene-ethylene copolymer comprising up to and including 7% by weight, preferably from 0.1 to 7% by weight, more preferably from 0.1 to 5% by weight, based on the weight of (A4.1a), of units deriving from ethylene; and (A4.2a) 20-45% by weight, preferably 20-40% by weight, more preferably 25-40% by weight of an ethylene-butene- 1 copolymer comprising 10-40 % by weight, preferably 20-30% by weight, based on the weight of (A4.2a), of units deriving from butene- 1, wherein the polypropylene composition (A4a) comprises:

[0085] - a total amount of up to and including 40% by weight, preferably from 0.1 to 40% by weight, based on the weight of (A4a), of units deriving from ethylene and butene- 1;

[0086] - a xylene soluble fraction from 15% to 35% by weight, preferably from 18% to 35% by weight, more preferably from 18% to 30% by weight, based on the weight of (A4a);

[0087] and wherein the polypropylene composition (A4a) has an intrinsic viscosity of the xylene soluble fraction equal to or lower than 1.7 dl/g, preferably from 0.8 to 1.7 dl/g, more preferably from 1.0 to 1.6 dl/g,

[0088] the amounts of (A4.1a) and (A4.2a) being based on the total weight of (A4. la)+(A4.2a), the total weight being 100%.

[0089] The propylene polymer compositions (A3) and (A4), including (A4a), are available on the market and can be obtained by melt blending the matrix and the rubbery components or, preferably, by polymerizing the relevant monomers in at least two 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, wherein preferably, the component (A3.1) or (A4.1), including (A4.1a), are produced in the first polymerization stage. [0090] The monomers are polymerized in the presence of a catalyst selected from metallocene compounds, highly stereospecific Ziegler-Natta catalyst systems as described above and combinations thereof, preferably in the presence of a highly stereospecific Ziegler-Natta catalyst system as described above.

[0091] The polymerization process to obtain the polypropylene composition (A3) and (A4), including (A4a), can be carried out in continuous or in batch, either in liquid phase or in gas phase. [0092] The liquid-phase polymerization can be either in slurry, solution or bulk (liquid monomer). This latter technology is the most preferred for the liquid polymerization and can be carried out in various types of reactors such as continuous stirred tank reactors, loop reactors or plug-flow reactors.

[0093] The gas-phase polymerization can be carried out in fluidized or stirred, fixed bed reactors.

[0094] The reaction temperature is comprised in the range from 40°C to 90°C and the polymerization pressure is 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.

[0095] The molecular weight of the propylene copolymers obtained in the polymerization stages is regulated using chain transfer agents, such as hydrogen or ZnEt2.

[0096] In all the embodiments described above, the propylene polymer (A) preferably has at least one of the following properties:

[0097] - a melt flowrate (MFR(A)) measured according to ISO 1133 (230°C, 2.16Kg) ranging from 5 to 80 g/10min., preferably from 10 to 60 g/10min., more preferably from 10 to 50 g/10 min.; and/or

[0098] - a tensile modulus measured according to ISO 527-1,-2 equal to or greater than 900

MPa, preferably ranging from 900 MPa to 2000 MPa, more preferably from 900 MPa to 1500 MPa, still more preferably from 1000 MPa to 1400 MPa; and/or

[0099] - a tensile stress at yield measured according to ISO 527-1, -2 equal to or greater than

15 MPa, preferably ranging from 15 MPa to 50 MPa, more preferably from 20 to 40 MPa; and/or [0100] - a tensile strain at yield measured according to ISO 527-1, -2 ranging from 5% to 35%, preferably from 10% to 30%. [0101] In a further preferred embodiment, the propylene polymer (A) is endowed with all the properties above.

[0102] In one embodiment, the elastomeric component (B) is an ethylene copolymer (Bl) selected from ethylene copolymers with at least one alpha-olefin of formula CH2=CHR ² , wherein R ² is a linear or branched C1-C8 alkyl, preferably selected from butene- 1, hexene- 1, octene-1 and combinations thereof.

[0103] The ethylene copolymer (Bl) preferably comprises at least 20% by weight, more preferably from 20% to 50% by weight based on the weight of (Bl), of units deriving from the alpha-olefin.

[0104] Ethylene copolymers (Bl) are commercially available under the tradename of Engage, eg. Engage™ 8100 or Engage™ 8150, marketed by Dow®. Ethylene copolymers (Bl) are generally prepared using known processes, preferably solution polymerization processes carried out in the presence of a metallocene-based catalyst system.

[0105] In a preferred embodiment, the elastomeric component (B) is a saturated or unsaturated styrene or alpha-methylstyrene block copolymer (B2) preferably comprising up to and including 30% by weight of polystyrene, preferably from 10% to 30% by weight, more preferably from 15% to 25% by weight, based on the weight of (B2).

[0106] In a further preferred embodiment, the elastomeric component (B) is a styrene block copolymer (B2) selected from the group consisting of: polystyrene-polybutadiene-polystyrene (SBS), polystyrene-poly(ethylene-butylene)-polystyrene (SEBS), polystyrene-poly(ethylene- propylene)-polystyrene (SEPS), polystyrene-polyisoprene-polystyrene (SIS), polystyrene- poly(isoprene-butadiene)-polystyrene (SIBS) and mixtures thereof. More preferably the styrene block copolymer (B2) is a polystyrene-poly(ethylene-butylene)-polystyrene (SEBS).

[0107] The styrene block copolymer (B2) preferably has at least one of the following properties:

[0108] - MFR measured according to ASTM D1238 (230°C, 2.16 Kg) ranging from 5 to 80 g/10min., preferably from 10 to 60 g/10min., more preferably from 10 to 30 g/10 min; and/or [0109] - Shore A value measured according to ASTM 2240 (30 sec.) equal to or lower than

70, preferably ranging from 30 to 70, more preferably from 30 to 60.

[0110] In one further preferred embodiment, the styrene block copolymer is endowed with all the properties above. [0111] Styrene or alpha-methylstyrene block copolymers (B2) are prepared by ionic polymerization of the relevant monomers and are commercially available under the tradename of Kraton™ marketed by Kraton Polymers.

[0112] The glass fibers (C) comprised in the polyolefin composition preferably have diameter ranging from 5 to 20 pm, preferably from 8 to 15 pm and length equal to or lower than 10 mm, preferably ranging from 0.1 to 10 mm, more preferably from 1 to 8 mm, more preferably from 2 to 7 mm, still more preferably from 3 to 6 mm.

[0113] The compatibilizer (D) is optionally but preferably comprised in the polyolefin composition to increase the compatibility of the glass fibers with the components (A) and (B). The compatibilizer (D) is preferably a modified olefin polymer functionalized with polar compounds and, optionally, with a low molecular weight compound having a reactive polar group. Preferably, the modified olefin polymer is selected from polyethylenes, polypropylenes and mixtures thereof. [0114] The modified olefin polymers are selected from graft copolymers, block copolymers and mixtures thereof.

[0115] Preferably, the modified polymers are functionalized with groups derived from polar compounds, including but not limited to acid anhydrides, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl compounds, oxazoline, epoxides, ionic compounds and combinations thereof. Specific examples of said polar compounds are unsaturated cyclic anhydrides, their aliphatic diesters, and diacid derivatives.

[0116] Preferably, the compatibilizer (D) is a polyolefin, 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, Cl- 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.

[0117] In a preferred embodiment, the compatibilizer (D) is a polyethylene and/or a polypropylene grafted with maleic anhydride (MAH-g-PP and/or MAH-g-PE).

[0118] In a further preferred embodiment, the compatibilizer (D) is a polyethylene and/or a polypropylene grafted with maleic anhydride, having at least one of the following properties: [0119] - a maleic anhydride graft level equal to or greater than 0.5 wt.%, based on the component (B), more preferably of from 0.5 wt.% to 3.0 wt.%, still more preferably from 0.75% to 2.0%; and/or [0120] - a melt flow rate determined according to the method ISO 1133 (190°C, 2.16kg) ranging from equal to or greater than 80 g/10min., preferably ranging from 80 to 200 g/lOmin. [0121] In a preferred embodiment, the polyethylene and/or a polypropylene grafted with maleic anhydride has all the properties above.

[0122] Modified polymers are known in the art and 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.

[0123] 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.

[0124] In a preferred embodiment, the polyolefin composition further comprises up to and including 1.0% by weight, preferably from 0.01 to 1.0% by weight, of a clarifying and/or a nucleating agent (E), wherein the amount of (E) is based on the total weight of (A)+(B)+(C)+(D)+(E), the total weight being 100%. Polyolefin compositions comprising a nucleating agent and/or a clarifying agent (E) have lower light absorbance.

[0125] Preferably, the polyolefin composition optionally comprises up to and including 3.0% by weight, of at least one further additive selected from the group consisting of antistatic agents, anti-oxidants, light stabilizers, slipping agents, anti-acids, melt stabilizers, and combinations thereof, wherein the amount of the further additive is based on the total weight of the polyolefin composition comprising the further additive.

[0126] The polyolefin composition preferably has at least one of the following properties: [0127] - flexural modulus measured according to ISO 178/A:2019-04 on injection molded specimens obtained according to EN ISO 20753 (Type B2) equal to or greater than 800 MPa, preferably equal to or greater than 1000 MPa, more preferably equal to or greater than 1100 MPa; and/or

[0128] - Charpy impact strength according to ISO 179/-leA:2010-ll (notched, 23°C) measured on injection molded specimens obtained according to EN ISO 20753 (Type B2) ranging from 10 to 45 kJ/m ² , preferably from 15 to 35 kJ/m ² ; and/or [0129] - Charpy impact strength according to ISO 179/-leA:2010-l 1 (notched, -30°C) measured on injection molded specimens obtained according to EN ISO 20753 (Type B2) ranging from 1 to 10 kJ/m ² , preferably from 1.5 to 8 kJ/m ² ; and/or

[0130] - the shrinkage in longitudinal direction, measured according to the method described in the experimental section, lower than 0.70%, preferably lower than 0.50%; and/or [0131] - the shrinkage in the transversal direction, measured according to the method described in the experimental section, lower than 1.00%, preferably lower than 0.85%; and/or [0132] - haze on lmm-thick plaques, measured according to the method described in the experimental section, equal to or greater than 85%, preferably equal to or greater than 95%; and/or [0133] - absorbance ABSi at any wavelengths ranging from 380 to 780 nm, measured on a

100pm-thick film according to the method described in the experimental section, lower than 0.70, preferably lower than 0.60; and/or

[0134] - absorbance ABS2(380) and/or ABS2(780), preferably both, measured respectively at

380 nm and 780nm on lmm-thick plaques obtained according to the method described in the experimental section, equal to or lower than 1.6; and/or

[0135] - the variation of absorbance AABS2, measured on lmm-thick plaques obtained according to the method described in the experimental section, equal to or lower than 0.4, preferably equal to or lower than 0.3, wherein the variation of the absorbance is determined by the following equation:

AABS ₂ = I 4BS ₂ (380) — 4BS ₂ (780) |

[0136] in which ABS2(380) is the absorbance measured at a wavelength of 380nm and ABS2(780) is the absorbance measured at 780nm.

[0137] In a preferred embodiment, the polyolefin composition is endowed with all the properties above.

[0138] The polyolefin composition is preferably obtained by melt blending the components (A), (B), (C) and, optionally, (D) and (E) in a conventional melt blending equipment, preferably a twin-screw extruder, thereby forming a molten polyolefin composition and subsequently push the molten polyolefin composition through a die and solidify the molten polyolefin composition. [0139] In one embodiment, the polyolefin composition comprises up to and including 10% by weight of at least one organic or inorganic pigment. The optical properties above are referred to the polyolefin composition not comprising the pigment. [0140] In one embodiment, the covering for a light-source according to the present disclosure consists of the polyolefin composition described above.

[0141] The polyolefin composition described above is endowed with a balance of optical and mechanical properties which render the composition suitable for use as covering for a light-source. [0142] Accordingly, the present disclosure refers also to the use of the polyolefin composition as described above as covering for a light-source.

[0143] A method for covering a light-source is also disclosed, the method comprising:

[0144] (a) shaping the polyolefin composition as described above, thereby obtaining a covering; and

[0145] (b) positioning the covering before a light-source to at least partially shield the light.

[0146] In a further aspect, the present disclosure refers to a process for manufacturing a covering for a light-source comprising the use of the polyolefin composition, wherein the process preferably comprises a step (i) of shaping the polyolefin composition by injection molding, cast extrusion, profile extrusion, rotational molding, blow molding or deep drawing.

[0147] In one embodiment, the covering for a light-source is a sheet having thickness of up to and including 30 mm, preferably ranging from 1 to 10 mm.

[0148] The features describing the subject matter of the present disclosure are not inextricably linked to each other. As a consequence, a certain level of preference of one feature does not necessarily involve the same level of preference of the remaining features of the same or different components. It is intended in the present disclosure that any preferred range of features of components from (A) to (E) from which the polyolefin blend is obtained can be combined independently from the level of preference, and that components from (A) to (E) can be combined with any possible additional component, and its features, described in the present disclosure. [0149] EXAMPLES

[0150] The following examples are illustrative only, and are not intended to limit the scope of the disclosure in any manner whatsoever.

[0151] CHARACTERIZATION METHODS

[0152] The following methods are used to determine the properties indicated in the description, claims and examples.

[0153] 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). [0154] 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.

[0155] C2 content in propylene-ethylene copolymer (II): ¹³ C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cryoprobe, 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 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.

[0156] PPP = 100 Tpp/S [0157] PPE = 100 T _bd /S

[0158] EPE = 100 T ₅₅ /S

[0159] PEP = 100 Spp/S

[0160] PEE= 100 Sps/S

[0161] EEE = 100 (0.25 S _Y§ +0.5 S ₅₅ )/S

[0162] Where S = Tpp + Trd + Tdd + Spp + Spe + 0.25 S _Y e+ 0.5 See

[0163] Tensile Modulus, Stress and Strain at yield: Determined according to the method ISO 527-1,-2:2019 on specimens according to ISO 20753-AE2018-10.

[0164] Flexural Modulus: determined according to ISO 178/A:2019-04 on injection molded specimens Type B2 according to ISO 20753.

[0165] Charpy impact strength: measured according to ISO 179 leA, notched at 23°C and - 30°C on injection molded specimens Type B2 according to ISO 20753.

[0166] Thermal shrinkage: a plaque of 195 x 100 x 2.5 mm is molded in an injection molding machine Krauss Maffei KM250/1000C2 (250 tons of claiming force) under the following injection molding conditions:

- melt temperature: 220°C;

- mold temperature: 35°C;

- injection time: 3.6 s;

- holding time: 30 s;

- screw diameter: 55 mm

The plaque was annealed at 23°C for 48h. Afterwards, the length (L) and the width (W) of the plaque were measured. The thermal shrinkage is calculated according to the following formulas: longitudinal shrinkage = [(195 — L)/195] x 100 transversal shrinkage = [(100 — I/F)/100] x 100 wherein

195 and L are respectively the dimension of the mold and the measured dimensions of the plaque along the flow direction, in mm; and

100 and W are respectively the dimension of the mold and the measured dimensions of the plaque crosswise the flow direction, in mm.

The values indicated in the tables are the arithmetic mean of measures taken on five plaques. [0167] Haze: the method determines the percentage of transmitted light that deviates from the incident beam by forward scattering when passing through the specimen and is in accordance with ASTM D1003 (non-compensated method). Only light deviating more than 2.5° is considered to be haze. The haze value is determined using a hazemeter such as BYK-Gardner Hazegard Plus, or an equivalent instrument with CIE illuminant C and an integrated sphere geometry in accordance with ASTM D1003. lmm-thick plaques are conditioned at 23±2°C and 50±10% humidity for 24h prior to testing. The plaques are placed in contact with the haze port and measurements are made at the center of the test specimen. The haze value is automatically calculated by the test instrument based on the following formula:

Haze [%] = T _d /T _t x 100 wherein Td is the diffuse transmittance and Tt is the total transmittance.

[0168] Absorbance: the absorbance in the UY-VIS spectrum was measured directly on 1 OOpm-thik films and on lmm-thick injection molded plaques with an Evolution™ 220 Spectrophotometer (by Thermo Fischer Scientific) under the following conditions:

- scan: 380-800nm

- speed: 200 nm/min

- slit: 2nm

- data interval: 1 nm.

[0169] Total light transmittance: the method determines the percentage of transmitted light when passing through the specimen. The transmittance value is determined using a hazemeter such as Hazegard Hazemeter XL-211, or an equivalent instrument and an integrated sphere geometry to collet light that is scattered. The collected light is measured with a photodetector whose spectral sensitivity has been modified by means of filters to approximate the response of the 1931 CIE standard Observer for Source C. The 3 mm-thick plaques are conditioned at 23±2°C and 50±10% humidity for at least 48h prior to testing. After calibrating the equipment to adjust to 100% of transmission the plaques are placed in contact with the haze / transmittance port and measurements are made at the center of the test specimen. The total light transmittance value is automatically calculated by the test instrument.

[0170] Injection molded plaques for haze and absorbance determination: lmm-thick plaques were obtained using an injection molding machine Negri Bossi VE70 operated in the following conditions: - screw rotation speed: 125 rpm

- back pressure: 100 bar

- mold temperature: 40°C

- melt temperature: 230°C

- injection time: 1 sec

- 1 ^st hold pressure stage time: 20 sec

- 2 ^nd hold pressure stage time: 5 sec

- cooling time: 10 sec

The two-cavity mold was in accordance with ISO 294-3:2020 (D11).

[0171] Injection molded plaques for light transmission determination: 3 mm-thick plaques were obtained using an injection molding machine Krauss Maffei CX 160-750 (160 tons of claiming force) operated in the following conditions: screw rotation speed: 100 rpm back pressure: 5 bar mold temperature: 35°C melt temperature: 220°C injection time: 4 sec hold pressure: 35 bar hold pressure stage time: 10 sec cooling time: 35 sec

[0172] Films preparation: 100 pm -thick films for optical measures were produced by compression molding using a Constant Thickness Film-Maker supplied by Specac Ltd. (diameter 29 mm) equipped with a proper ring/separator and a Carver press operated at 190°C and 2 tons of pressure.

[0173] RAW MATERIALS:

[0174] PP1 : a propylene-ethylene-butene-1 terpolymer containing 1.1 wt.% ethylene units and 5.3 wt.% of butene- 1 units, and having a xylene soluble fraction of 5.0 wt.%, was prepared according to the polymerization process described in Example 1 of WO2014/198459. The polymer particles obtained from the reactor were mixed in the molten state with 0.4 wt.% of Millad ^® NX ^® 8000, 0.05 wt.% of calcium stearate, 0.1 wt.% of glyceryl monostearate (GMS 90), 0.1 wt.% of Irgafos® 168 and 0.05 wt.% of an antioxidant. The extruder was operated under nitrogen atmosphere at a rotational speed of 250 rpm and a temperature of 200-250°C. The properties of the obtained material are reported in Table 1.

[0175] PP2: polypropylene composition comprising a propylene-ethylene random copolymer containing 3.0 wt.% of ethylene units, the composition having a xylene soluble fraction of 6 wt.%. The polypropylene composition was produced in two loop reactors, according to the polymerization process described in Example 1 of W02006/018813. The polymer particles obtained from the reactor were mixed in the molten state with 0.18 wt.% of DMDBS, 0.05 wt.% of calcium stearate, 0.05 wt.% of glyceryl monostearate (GMS 90), 0.1 wt.% oflrgafos® 168 and 0.05 wt.% of an antioxidant. The extruder was operated under nitrogen atmosphere at a rotational speed of 250 rpm and a temperature of 200-250°C. The properties of the obtained material are reported in Table 1.

[0176] PP3: polypropylene composition comprising 31 wt.% of a propylene-ethylene copolymer having MFR (ISO 1133; 230°C, 2.16Kg) of 39 g/lOmin. and 69 wt.% of an ethylene- butenel copolymer. The polypropylene composition has a xylene soluble fraction of 20 wt.% and an intrinsic viscosity of the xylene soluble fraction of 1.45 dl/g. The composition comprises 24 wt.% of units deriving from ethylene, 7.2 wt.% of units deriving from butene- 1 and was obtained according to the polymerization process described in Examples 1-3 of W02004/003073. The polymer particles obtained from the reactor cascade were mixed in the molten state with 0.18 wt.% of DMDBS, 0.05 wt.% of calcium stearate, 0.05 wt.% of glyceryl monostearate (GMS 90), 0.1 wt.% oflrgafos® 168 and 0.05 wt.% of an antioxidant. The extruder was operated under nitrogen atmosphere at a rotational speed of 250 rpm and a temperature of 200-250°C. The properties of the obtained material are reported in Table 1.

Table 1 [0177] Moplen HF501N, a propylene homopolymer from LyondellBasell, having a melt flow rate of 12 g/10 mm. (IS01133; 230°C/2.16Kg) and tensile modulus (ISO 527-1,-2:2019) of 1550 MPa.

[0178] Kraton™ G1643 V from Kraton Corp., a linear styrene triblock copolymer based on styrene and ethylene/butylene containing 20 wt.% of polystyrene, having MFR (ASTM D1238; 230°C, 2.16 Kg) of 19 g/lOmin. and Shore A value (ASTM D2240, 30 sec.) of 52.

[0179] Kraton G1657 V from Kraton Corp., a linear triblock copolymer based on styrene and ethylene/butylene with a polystyrene content of 13 wt.%, having MFR (ASTM D1238; 230°C and 5Kg) of 22 g/10 min. and a Shore A value (ASTM D2240, 10 sec.) of 47.

[0180] GF ECIO 636: ThermoFlow ^® 636 from Johns Manville, chopped E-glass fibers having fiber diameter of 10 pm and chopped strands length of 4mm.

[0181] Bondyram ^® 1101, from Polyram Plastic Industries LTD, is a maleic anhydride modified polypropylene compound with a maleic anhydride content (FTIR) of 1 wt.% and a melt flow index (ISO 1133, 190°C/2.16 Kg) of 170 g/lOmin.

[0182] DMDBS, l,3:2,4-bis(3,4-dimethyldibenzylidene) sorbitol, Millad 3988 supplied by Milliken Chemical.

[0183] Millad ^® NX ^® 8000, a clarifying agent supplied by Milliken Chemical.

[0184] Irgafos ^® 168, a processing stabilizer supplied by BASF.

[0185] Comparative examples CE1-CE2 and examples E3-E5

[0186] PP1 was melt blended with the components reported in table 2 in a twin screw extruder Doppelschneckenextruder 40 mm from Werner & Pfleiderer (Stuttgart, Germany) having screw length to diameter ratio of 48, operated under nitrogen atmosphere in the following conditions: [0187] screw rotation speed: 300 rpm;

[0188] melt temperature: from 190° to 200°C.

[0189] The polypropylene compositions were tested for mechanical and optical properties and the results are illustrated in Table 2.

Table 2

[0190] Comparative examples CE6-CE7 and examples E8-E10

[0191] PP2 was melt blended with the components reported in Table 3 using the same extruder and extruding conditions used in the preceding examples.

[0192] The polypropylene compositions were tested for mechanical and optical properties and the results are illustrated in Table 3.

Table 3

[0193] Comparative examples CE11-CE12 and examples E13-E15

[0194] PP3 was melt blended with the components reported in Table 4 using the same extruder and extruding conditions used in the preceding examples.

[0195] The polypropylene compositions were tested for mechanical and optical properties and the results are illustrated in Table 4.

Table 4

The absorbance ABSi of IOOmih thick films at wavelength from 280 to 990 nm was measured for the compositions of comparative examples CE11-CE12 and for examples E13-E15. Plot of the absorbance as function of the wavelength is illustrated in FIG. 1.

[0196] Example E16

[0197] Values of the mechanical properties and of the total light transmittance, measured on

3mm-thick plaques, of a polyolefin composition according to the present disclosure are reported in Table 5.

Table 5