Light-coloured polypropylene-based compositions

Abstract

The present invention relates to a polymer composition comprising polypropylene and glass fibers. The polymer composition according to the present invention has a white or light color and an excellent impact resistance retention.

Description

[0001] The present invention relates to a polymer composition comprising polypropylene and glass fibers. The present invention further relates to a process for preparing said polymer composition and to an article comprising said polymer composition, and to the use of the polymer composition in an article.

[0002] Polymer compositions comprising polypropylene and glass fibers are known in the art. Depending on the application, color pigments can be used in the polymer composition. In order to achieve light colors, pigments having a pure color are typically compounded with white pigments. For example, in order to achieve a light blue color, a pure blue pigment can be compounded with a white pigment. Typically, white pigments lead to a significant deterioration of the impact properties, in particular the low temperature impact resistance, of the polymer composition.

[0003] Antenna housings are used at antenna stations to provide protection for the antenna from environmental influences. Therefore, it is desirable that the antenna housing is made of a polymer composition having sufficient rigidity and high low temperature impact resistance to withstand extreme weather, such as strong winds or hail. A further common requirement for polymer compositions used in antenna housings is light color, which is for aesthetic reasons, since antennas are typically installed at high altitudes, light colors match the color of the sky better. Antenna housings based on polymer compositions comprising polypropylene are known in the art, for example:

[0004] EP 1852938 B1 discloses an antenna housing comprising an electromagnetic window portion through which electromagnetic signals pass in use, wherein the wall layer of the electromagnetic window is formed from a self-reinforced polypropylene.

[0005] US 20170190884 A1 discloses a resin composition for a radome. The resin composition comprises carbon nanotubes and a polymer resin. The resin composition does not interfere with signal transmission from a radar while protecting the radar from the surrounding environment.

[0006] The white or light color of the polymer composition can be achieved by adding white pigments to the polymer composition, but this tends to lead to poor impact properties, there is still a need to provide a polymer composition having a white or light color and excellent impact resistance retention.

[0007] This need is met in the present invention by a polymer composition comprising polypropylene, glass fibers and a pigment comprising an inorganic zinc salt and an inorganic barium salt; wherein the MFI of the polypropylene is 17 to 75 dg / min, determined according to ISO 1133 at 230 °C / 2.16 kg, wherein the xylene soluble fraction of the polypropylene is 9.3 to 19.6 wt.-%, determined according to ISO 16152:2005, wherein the amount of polypropylene is 29.6 to 79.8 wt.-%, based on the total amount of the polymer composition, wherein the amount of glass fibers is 17 to 34 wt.-%, based on the total amount of the polymer composition.

[0008] The inventors of the present application surprisingly found that the composition according to the present application has a white or light color and an excellent impact resistance retention.

[0009] In the context of the present application, "white or light color" means that the L value of the polymeric composition is at least 79, wherein the L value is determined according to ISO 11664-4:2008. In the context of the present application, "excellent impact resistance retention" means that the ratio between the impact resistance of a composition comprising 4 wt.-% of a white pigment and the impact resistance of a composition wherein the 4 wt.-% of the white pigment is replaced by 4 wt.-% of the polypropylene according to the present application is at least 0.70, wherein the impact resistance is determined according to ISO 180:2000 at 23 °C.

[0010] Preferably, the present application relates to a polymeric composition comprising a polypropylene having a MFI of 17 to 75 dg / min determined according to ISO 1133 at 230 °C / 2.16 kg, a glass fiber, a pigment comprising an inorganic zinc salt and an inorganic barium salt, and a polyolefin-based elastomer having a MFI of 0.8 to 14.2 dg / min determined according to ASTM D1238-13 at 190 °C, 2.16 kg, wherein the amount of the polypropylene is 29.6 to 79.8 wt.-% based on the total amount of the polymeric composition, wherein the amount of the glass fiber is 17 to 34 wt.-% based on the total amount of the polymeric composition, wherein the density of the polyolefin-based elastomer is 0.853 to 0.860 g / cm3 determined according to ASTM D792-13, wherein the amount of the pigment is 0.1 to 0.5 wt.-% based on the total amount of the polymeric composition. 3 wherein the MFI of the polyolefin-based elastomer is 0.8 to 14.2 dg / min determined according to ASTM D1238-13 at 190 °C, 2.16 kg. Such a polymeric composition can have an excellent low temperature dart impact resistance.

[0011] Polypropylene

[0012] The polypropylene according to the present application is preferably a heterophasic propylene copolymer, wherein the heterophasic propylene copolymer can be produced in one or more reactors by polymerizing propylene and, optionally, subsequently polymerizing an ethylene-a-olefin mixture in the presence of a catalyst.

[0013] The polypropylenes according to the present application can be produced using any conventional technique known to the skilled person, for example a multi-stage process polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combination thereof. Any conventional catalyst system can be used, for example Ziegler-Natta or metallocene. Such techniques and catalysts are described for example in WO06 / 010414; Servander Ven, Polypropylene and other Polyolefins, Studies in Polymer Science 7, Elsevier 1990; WO06 / 010414, US4399054 and US4472524. Preferably, the polypropylenes are made using a Ziegler-Natta catalyst.

[0014] Preferably, the polypropylenes according to the present application consist of a propylene-based matrix and dispersed ethylene-a-olefin copolymer.

[0015] Preferably, the amount of propylene-based matrix is 60 to 99 wt.-%, for example 65 to 95 wt.-%, for example 70 to 90 wt.-%, for example 75 to 85 wt.-%, for example 80 to 85 wt.-%, based on the total amount of polypropylene.

[0016] Preferably, the amount of dispersed ethylene-a-olefin copolymer is 40 to 1 wt.-%, for example 35 to 5 wt.-%, for example 30 to 10 wt.-%, for example 25 to 15 wt.-%, based on the total amount of polypropylene.

[0017] The total amount of propylene-based matrix and dispersed ethylene-a-olefin copolymer is preferably 100 wt.-%. The ratio of the amounts of propylene-based matrix and dispersed ethylene-a-olefin copolymer is preferably 95:5 to 65:35, preferably 90:10 to 70:30, preferably 85:15 to 75:25.

[0018] The amounts of propylene-based matrix and dispersed ethylene-a-olefin copolymer can be determined by NMR, which is well known in the art.

[0019] The propylene-based matrix can consist of a propylene homopolymer and / or a propylene-a-olefin copolymer consisting of at least 70 wt.-% propylene and at most 30 wt.-% ethylene and / or an a-olefin having 4 to 10 carbon atoms, for example, a propylene-a-olefin copolymer consisting of at least 80 wt.-% propylene and at most 20 wt.-% ethylene and / or an a-olefin having 4 to 10 carbon atoms, for example, a propylene-a-olefin copolymer consisting of at least 90 wt.-% propylene and at most 10 wt.-% ethylene and / or an a-olefin having 4 to 10 carbon atoms, based on the total amount of propylene-based matrix.

[0020] The alpha-olefin in the propylene-alpha-olefin copolymer can be selected from the group consisting of ethylene and alpha-olefins having 4 to 10 carbon atoms, such as 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene and mixtures thereof, preferably the alpha-olefin in the propylene-alpha-olefin copolymer is ethylene.

[0021] Preferably, the propylene-based matrix is a propylene homopolymer.

[0022] Preferably, the propylene-based matrix has a melt flow index (MFI) MFI PP of at least 30 dg / min and at most 120 dg / min, determined according to ISO 1133 (2.16 kg / 230°C). The MFI PP may for example be at least 40 dg / min, at least 45 dg / min, at least 50 dg / min, at least 55 dg / min or at least 60 dg / min, and / or for example at most 110 dg / min, at most 100 dg / min, at most 90 dg / min or at most 80 dg / min, determined according to ISO 1133 (2.16 kg / 230°C).

[0023] The propylene-based matrix is preferably semi-crystalline, that is, it is not 100% amorphous nor is it 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, such as at least 50%, such as at least 60% crystalline and / or such as at most 80% crystalline, such as at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60-70%. For the purposes of the present invention, the crystallinity of the propylene-based matrix is determined according to ISO 11357-1 and ISO 11357-3 from 1997, using differential scanning calorimetry (DSC), using a scan speed of 10 °C / minute, a sample of 5 mg, and a second heating curve using 207.1 J / g as the theoretical standard for 100% crystalline material.

[0024] The MFI (MFI EPR ) of the dispersed ethylene-alpha-olefin copolymer may for example be at least 0.001 dg / min, at least 0.01 dg / min, at least 0.1 dg / min, at least 0.3 dg / min, at least 0.7 dg / min, at least 1 dg / min, and / or for example at most 30 dg / min, at most 20 dg / min, at most 15 dg / min, at most 10 dg / min, at most 5 dg / min, at most 3 dg / min, determined according to ISO 1133 (2.16 kg / 230°C).

[0025] The amount of ethylene in the ethylene-a-olefin copolymer is preferably from 20 to 80 wt.-%, based on the ethylene-a-olefin copolymer, more preferably the amount of ethylene in the ethylene-a-olefin copolymer is from 30 to 70 wt.-%, more preferably from 40 to 65 wt.-%, more preferably from 50 to 65 wt.-%, even more preferably from 55 to 65 wt.-%.

[0026] Preferably, the a-olefin in the ethylene-a-olefin copolymer is propylene.

[0027] The MFI of the polypropylene is from 17 to 75 dg / min, preferably from 20 to 60 dg / min, more preferably from 25 to 55 dg / min, even more preferably from 28 to 40 dg / min, determined according to ISO 1133 (2.16 kg / 230 °C).

[0028] The xylene soluble fraction of the polypropylene according to the present application is from 9.3 to 19.6 wt.-%, preferably from 11.2 to 18.4 wt.-%, more preferably from 12.4 to 17.4 wt.-%, determined according to ISO 16152:2005. The intrinsic viscosity of the xylene soluble fraction of the polypropylene is preferably from 1.2 to 4.6 dl / g, preferably from 1.8 to 4.0 dl / g, even more preferably from 2.3 to 3.5 dl / g, determined according to ISO 1628-1 :2009 in decalin at 135 °C.

[0029] The amount of polypropylene is from 29.6 to 79.8 wt.-%, preferably from 47.1 to 77.2 wt.-%, based on the total amount of the polymer composition.

[0030] Glass fibers

[0031] Generally, a glass fiber is a glassy cylindrical substance in which its length is significantly longer than the diameter of its cross section. It is well known that the addition of glass fibers can improve the mechanical properties (e.g. strength and stiffness) of a polymer resin. The degree of property improvement depends to a large extent on the properties of the glass fiber, e.g. the diameter, length and surface properties of the glass fiber.

[0032] For the purpose of the present application, the diameter of the glass fiber is preferably from 5 to 50 micrometers, preferably from 10 to 30 micrometers, more preferably from 15 to 25 micrometers.

[0033] It is also known that long glass fibers (length from 0.5 to 50 mm) can provide more superior property improvement to a composition than short glass fibers (length shorter than 0.5 mm). The length of the glass fiber in the present application depends to a large extent on the process used to prepare the composition. Preferably, the glass fiber in the polymer composition according to the present application is a long glass fiber.

[0034] In the present invention, the amount of glass fibers is 17 to 34 wt.-%, preferably 26 to 32 wt.-%, based on the total amount of the polymer composition.

[0035] The total amount of polypropylene and glass fibers is preferably at least 81 wt.-%, more preferably at least 87 wt.-%, more preferably at least 91 wt.-%, based on the total amount of the polymer composition.

[0036] Pigments

[0037] The pigment comprises and preferably consists of inorganic zinc salts and inorganic barium salts. Preferably the pigment is a white pigment. Pigments are capable of changing the color of reflected or transmitted light as a result of wavelength-selective absorption. Pigments are finely divided solids that are essentially insoluble in their polymeric applications medium. Pigments are introduced into plastics by a dispersion process while the plastic is in the molten phase, and after the plastic solidifies, the dispersed pigment particles are physically retained in the solid polymer matrix.

[0038] In the present invention, a "salt" is defined as "a compound that consists of an assembly of cations and anions" (Compendium of Chemical Terminology, 2ndEd. (1997), pp. 1329, IUPAC, compiled by A. D. McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford (1997), online version (2019-), ISBN 0-9678550-9-8). According to this definition, metal salts are considered to be metal compounds, e.g. inorganic zinc salts are inorganic zinc compounds, inorganic barium salts are inorganic barium compounds.

[0039] The molar ratio between the inorganic zinc salt and the inorganic barium salt is preferably 0.3 to 1.7, more preferably 0.5 to 1.5, even more preferably 0.8 to 1.2.

[0040] The total amount of inorganic zinc salt and inorganic barium salt is preferably 1.3 to 6.2 wt.-%, more preferably 1.8 to 5.4 wt.-%, even more preferably 2.3 to 4.8 wt.-%, based on the total amount of the polymer composition.

[0041] The inorganic zinc salt according to the present invention is selected from the group consisting of zinc sulfide, zinc oxide and mixtures thereof, preferably the inorganic zinc salt is zinc sulfide.

[0042] The inorganic barium salt according to the present invention is selected from the group consisting of barium carbonate, barium sulfate, barium chloride and mixtures thereof, preferably the inorganic barium salt is barium sulfate.

[0043] Preferably, the inorganic zinc salt according to the present invention is zinc sulfide and the inorganic barium salt according to the present invention is barium sulfate.

[0044] Polyolefin-based elastomers

[0045] The polymer composition of the present invention preferably also comprises a polyolefin-based elastomer.

[0046] The polyolefin-based elastomer is preferably selected from ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer and mixtures thereof, more preferably wherein the elastomer is selected from ethylene-1-octene copolymer. Most preferably, the elastomer is ethylene-1-octene copolymer.

[0047] Preferably, the density of the polyolefin-based elastomer is preferably from 0.845 to 0.883 g / cm² as measured according to ASTM D792-13. 3 , preferably 0.848 to 0.865 g / cm 3 , more preferably 0.853 to 0.860 g / cm 3 .

[0048] Preferably, the polyolefin-based elastomer has an MFI of from 0.5 to 18.0, preferably from 0.8 to 14.2 dg / min, measured according to ASTM D1238-13, 190°C, 2.16 kg.

[0049] The Shore A hardness of the polyolefin-based elastomer is preferably from 35 to 90, preferably from 42 to 69, more preferably from 47 to 60, measured according to ASTM D2240-15, 1s.

[0050] The inventors of the present invention surprisingly found that a composite material comprising a composite material having an MFI of 0.8 to 14.2 dg / min as measured according to ASTM D1238-13, 190°C, 2.16 kg and 0.853 to 0.860 g / cm 3 The polymer composition according to the present invention based on a polyolefin elastomer having a density of 1000 Å has excellent drop weight impact resistance at -40°C.

[0051] Elastomers suitable for use in the present invention are commercially available, for example, under the trademark EXACT TM Available from Exxon Chemical Company of Houston, Texas, or under the trademark ENGAGE TM Polymers (a series of metallocene-catalyzed plastomers) are available from The Dow Chemical Company of Midland, Michigan, or under the trademark TAFMER TMavailable from MITSUI Chemicals Group of Minato Tokyo, or under the trademark Fortify TM and Cohere TM from SABIC.

[0052] The elastomer can be prepared using methods known in the art, for example by using a single-site catalyst, i.e. a catalyst whose transition metal component is an organometallic compound and at least one of its ligands has a cyclopentadienyl anion structure by which this ligand is bound coordinatively to the transition metal cation. Catalysts of this type are also referred to as "metallocene" catalysts. Metallocene catalysts are described, for example, in U.S. Pat. Nos. 5,017,714 and 5,324,820. The elastomer can also be prepared using a conventional type of heterogeneous multi-site Ziegler-Natta catalyst.

[0053] Preferably, the amount of ethylene incorporated in the polyolefin-based elastomer is at least 45 wt.%. More preferably, the amount of ethylene incorporated in the polyolefin-based elastomer is at least 48 wt.%, for example at least 50 wt.%. The amount of ethylene incorporated in the polyolefin-based elastomer can typically be at most 95 wt.%, for example at most 85 wt.%, for example at most 75 wt.%, for example at most 65 wt.%, for example at most 60 wt.%, for example at most 58 wt.%.

[0054] The amount of polyolefin-based elastomer is preferably 5-20 wt.%, more preferably 7-15 wt.%, based on the total amount of the polymer composition.

[0055] Optional additives

[0056] The thermoplastic polymer composition can further comprise usual additives, such as nucleating and clarifying agents, stabilizers, mold release agents, fillers, peroxides, plasticizers, antioxidants, lubricants, antistatic agents, crosslinking agents, anti-scratch agents, high performance fillers, impact modifiers, flame retardants, blowing agents, acid scavengers, recycling additives, coupling agents, antimicrobials, anti-fog additives, slip additives, anti-blocking additives, polymer processing aids, and the like. Such additives are well known in the art. The skilled person knows how to select the type and amount of additives such that they do not adversely affect the target properties.

[0057] A pigment other than the inorganic zinc salt and the inorganic barium salt can be added to the polymer composition, however, such a pigment should not deteriorate the white or light color and the impact properties of the polymer composition, wherein the composition preferably does not contain a pigment which deteriorates the L value of the polymer composition to below 70. Preferably, the composition does not contain a pigment which deteriorates the L value of the polymer composition to below 74, more preferably, the composition does not contain a pigment which deteriorates the L value of the polymer composition to below 79, wherein the L value is determined according to ISO 11664-4:2008, wherein the composition preferably does not contain a pigment which deteriorates the impact resistance retention of the polymer composition to a value below 0.62, preferably, the composition does not contain a pigment which deteriorates the impact resistance retention of the polymer composition to a value below 0.67, more preferably, the composition does not contain a pigment which deteriorates the impact resistance retention of the polymer composition to a value below 0.70, wherein the impact resistance is determined according to ISO 180:2000 at 23 °C, wherein the impact resistance retention is calculated as the ratio between the impact resistance of the composition comprising 4 wt% of the pigment and the impact resistance of the composition wherein the 4 wt% of the pigment is replaced by 4 wt% of PP, wherein the impact resistance is determined according to ISO 180:2000 at 23 °C.

[0058] The present application also relates to a process for the preparation of the polymer composition.

[0059] The polymer composition according to the present application can be prepared by processes known in the art for the preparation of fiber reinforced compositions, for example: pultrusion, wire coating as described in EP 0921919 B1 and EP 0994978 B1, or compounding.

[0060] The polymer composition prepared in this process is in the form of pellets.

[0061] The present application also relates to an article comprising the polymer composition according to the present application, wherein the article comprises preferably at least 90 wt%, preferably at least 95 wt%, more preferably at least 97 wt% of the polymer composition according to the present application based on the total amount of the article. Preferably, the article is an antenna housing.

[0062] The present application also relates to a process for the preparation of the article comprising the following steps in this order:

[0063] - providing the polymer composition according to the present application in the form of pellets.

[0064] - injection molding the polymer composition into the article.

[0065] The present application also relates to the use of the polymer composition according to the present application in an article, preferably the article is an antenna housing. Example:

[0066] Materials used:

[0067] Polypropylene (PP):

[0068] The polypropylene (PP) used to prepare the samples was commercially available from SABIC. The PP had an MFI of 30 dg / min, measured at 230°C / 2.16 kg according to ISO 1133. The PP had a xylene soluble fraction of 16.4 wt%, measured according to ISO 16152:2005, and an intrinsic viscosity of 3 dl / g, measured in decalin at 135°C according to ISO 1628-1:2009.

[0069] Glass fibers (GF):

[0070] The glass fiber used was standard Type 30 roving SE4220, supplied in roving packages by 3B, having a filament diameter of 19 microns and containing a sizing composition containing aminosilane.

[0071] Pigments:

[0072] The pigments used in the examples include titanium dioxide TiO2 ( 2233), zinc sulfide ZnS (SACHTOLITH HD from Sachtleben Chemie GmbH), and lithopone ZnS·BaSO 4 (B311 from Union Titanium Enterprise (Shanghai) co., limited).

[0073] Polyolefin-based elastomers:

[0074] Several grades of ethylene-octene copolymers commercially available from SABIC under the trademark Fortify were used. Their properties are summarized in Table 1:

[0075] Table 1 Properties of POE

[0076]

[0077] Additives and impregnants:

[0078] The additives used in the examples consisted of 1 wt% of a compatibilizer and 0.4 wt% of a stabilizer. The impregnating agent used in the examples was the same as that used in WO 2009 / 080281 A1, and the amount of the impregnating agent was 1.75 wt%. The amounts of the additives and impregnating agent were based on the total amount of the composition.

[0079] method:

[0080] The sample is prepared in the following order:

[0081] In a first step, the PP is melt-mixed with POE, white pigment and additives to prepare a thermoplastic resin in the form of granules.

[0082] In a second step, a polymer composition is prepared by the wire coating method described in the examples of WO 2009 / 080281 Al using the thermoplastic resin obtained in the first step, glass fibers and impregnating agent. The composition details of the polymer composition are given in Table 2.

[0083] In a third step, the granules of the polymer composition are injection molded into a plate. The size of the plate is suitable for the measurements.

[0084] Measurement methods:

[0085] Color measurement:

[0086] The color (L.a.b) of the samples with different pigments was tested according to ISO / CIE 11664-4:2019. The L values of the samples are shown in Table 2.

[0087] Rigidity:

[0088] The stiffness was determined by measuring the flexural modulus according to ISO 178:2010.

[0089] Impact resistance:

[0090] The impact resistance of the examples was measured by two methods: Izod test and drop hammer test.

[0091] - Izod measurements were performed according to ISO 180:2000 at 23 °C and -40 °C. The impact resistance retention was calculated as the ratio between the impact resistance of a composition comprising 4 wt% of pigment and the impact resistance of a composition wherein 4 wt% of the pigment was replaced by 4 wt% of PP, wherein the impact resistance was determined according to ISO 180:2000 at 23 °C and -40 °C.

[0092] - The drop hammer test was performed according to the following protocol:

[0093] The plate used in this measurement had the dimensions: 150*150*3 mm.

[0094] The drop hammer impact test was performed on a custom-made machine. This custom-made machine consists of two parts: a weight release mechanism and a plate holder.

[0095] The weight release mechanism was able to release a metal ball with a weight of 511 g and a diameter of 50 mm from a height of 1.3 m, which ball, as a free-falling object, produced a drop hammer impact on the test plate with an initial velocity of 0.

[0096] The plate holder has a square shape with a space in the center, the outer dimensions of the holder are 150*150 mm, the inner dimensions are 130*130 mm. The horizontal geometric center of the square outer part coincides with the horizontal geometric center of the square inner part. The plate is placed horizontally on the plate holder, the horizontal geometric center of the plate coincides with the horizontal geometric center of the holder.

[0097] The weight release mechanism and the plate holder are arranged in this way so that a drop hammer impact is generated vertically on the surface of the plate. The horizontal geometric center of the plate coincides with the horizontal geometric center of the impact point.

[0098] The plate is conditioned in a freezer at -40°C for at least 4 hours, after which it is mounted on the plate holder. The entire drop hammer impact operation is completed within 30 seconds from the plate being removed from the freezer.

[0099] After the drop hammer impact, the plate is visually inspected for the presence of cracks on its surface. 9 plates are tested for each formulation and the percentage of crack-free is calculated.

[0100] Table 2 Formulations and properties of the polymer compositions

[0101]

[0102]

[0103] According to CE1-CE3 and IE1 of Table 2, when compared to the reference example CE2, Ti02, ZnS and ZnS.BaS04provide similar whiteness levels, but these white pigments result in different levels of impact resistance retention, with IE1 containing ZnS.BaS04having the highest retention value, which is higher than 0.70 both at 23°C and at -40°C.

[0104] In IE2-IE4 of Table 2, IE4 represents the most preferred embodiment, since POE 3 in IE4 has an MFI and a density within the preferred ranges, IE4 shows better drop hammer impact resistance than IE2 and IE3.

Claims

1. A polymer composition comprising polypropylene, glass fibers, and a pigment comprising an inorganic zinc salt and an inorganic barium salt, wherein the polypropylene has an MFI of 17 to 75 dg / min, measured at 230° C. / 2.16 kg, according to ISO 1133, wherein the xylene soluble fraction of the polypropylene is 9.3 to 19.6 wt %, measured according to ISO 16152:2005, wherein the amount of the polypropylene is 29.6-79.8 wt %, based on the total amount of the polymer composition, wherein the amount of the glass fibers is 17-34 wt %, based on the total amount of the polymer composition, and the molar ratio between the inorganic zinc salt and the inorganic barium salt is 0.3 to 1.

7. 2 . The polymer composition according to claim 1 , wherein the molar ratio between the inorganic zinc salt and the inorganic barium salt is 0.5 to 1.

5. 3 . The polymer composition according to claim 1 , wherein a molar ratio between the inorganic zinc salt and the inorganic barium salt is 0.8 to 1.

2. 4 . The polymer composition according to claim 1 , wherein the total amount of the inorganic zinc salt and the inorganic barium salt is 1.3 to 6.2 wt % based on the total amount of the polymer composition. 5 . The polymer composition according to claim 1 , wherein the total amount of the inorganic zinc salt and the inorganic barium salt is 1.8 to 5.4 wt % based on the total amount of the polymer composition. 6 . The polymer composition according to claim 1 , wherein the total amount of the inorganic zinc salt and the inorganic barium salt is 2.3 to 4.8 wt % based on the total amount of the polymer composition.

7. The polymer composition according to any one of claims 1 to 3, wherein the inorganic zinc salt is selected from zinc sulfide, zinc oxide and mixtures thereof.

8. The polymer composition according to any one of claims 1 to 3, wherein the inorganic zinc salt is zinc sulfide.

9. The polymer composition according to any one of claims 1 to 3, wherein the inorganic barium salt is selected from the group consisting of barium carbonate, barium sulfate, barium chloride and mixtures thereof.

10. The polymer composition of any one of claims 1 to 3, wherein the inorganic barium salt is barium sulfate.

11. The polymer composition according to any one of claims 1 to 3, wherein the polypropylene has an MFI of 20 to 60 dg / min, measured according to ISO 1133 at 230°C / 2.16 kg.

12. The polymer composition according to any one of claims 1 to 3, wherein the polypropylene has an MFI of 25 to 55 dg / min, measured according to ISO 1133 at 230°C / 2.16 kg.

13. The polymer composition according to any one of claims 1 to 3, wherein the polypropylene has an MFI of 28 to 40 dg / min, measured according to ISO 1133 at 230°C / 2.16 kg.

14. The polymer composition according to any one of claims 1 to 3, wherein the xylene soluble fraction of the polypropylene is 11.2 to 18.4 wt% as determined according to ISO 16152:2005.

15. The polymer composition according to any one of claims 1 to 3, wherein the xylene soluble fraction of the polypropylene is 12.4 to 17.4 wt% as determined according to ISO 16152:2005.

16. The polymer composition according to any one of claims 1 to 3, wherein the intrinsic viscosity of the xylene soluble fraction of the polypropylene is 1.2 to 4.6 dl / g, measured according to ISO 1628-1:2009 in decalin at 135°C.

17. The polymer composition according to any one of claims 1 to 3, wherein the intrinsic viscosity of the xylene soluble fraction of the polypropylene is 1.8 to 4.0 dl / g, measured according to ISO 1628-1:2009 in decalin at 135°C.

18. The polymer composition according to any one of claims 1 to 3, wherein the intrinsic viscosity of the xylene soluble fraction of the polypropylene is 2.3 to 3.5 dl / g, measured in decalin at 135°C according to ISO 1628-1:2009.

19. The polymer composition of any one of claims 1-3, wherein the polymer composition further comprises a polyolefin-based elastomer, wherein the polyolefin-based elastomer is an ethylene-1-octene copolymer.

20. The polymer composition of claim 19, wherein the polyolefin-based elastomer has a Shore A hardness of 35 to 90 as measured according to ASTM D2240-15, 1s.

21. The polymer composition of claim 19, wherein the polyolefin-based elastomer has a Shore A hardness of 42 to 69 as measured according to ASTM D2240-15, 1s.

22. The polymer composition of claim 19, wherein the polyolefin-based elastomer has a Shore A hardness of 47 to 60 as measured according to ASTM D2240-15, 1s.

23. The polymer composition of claim 19, wherein the polyolefin-based elastomer has a density of 0.845 to 0.883 g / cm² as measured according to ASTM D792-13. 3 .

24. The polymer composition of claim 19, wherein the polyolefin-based elastomer has a density of 0.848 to 0.865 g / cm² as measured according to ASTM D792-13. 3 .

25. The polymer composition of claim 19, wherein the polyolefin-based elastomer has a density of 0.853 to 0.860 g / cm² as measured according to ASTM D792-13. 3 .

26. The polymer composition of claim 19, wherein the total amount of polypropylene and glass fiber is at least 81 wt% based on the total amount of the polymer composition.

27. The polymer composition of claim 19, wherein the total amount of polypropylene and glass fiber is at least 87 wt% based on the total amount of the polymer composition.

28. The polymer composition of claim 19, wherein the total amount of polypropylene and glass fiber is at least 91 wt% based on the total amount of the polymer composition.

29. A method for preparing an article, comprising the following steps in the following order. - providing a polymer composition according to any one of claims 1 to 28 in the form of pellets, - Injection molding the polymer composition into an article.

30. An article comprising at least 90% by weight of the polymer composition according to any one of claims 1 to 28, based on the total amount of the article.

31. The article of claim 30, comprising at least 95 wt% of the polymer composition based on the total weight of the article.

32. The article of claim 30, comprising at least 97 wt% of the polymer composition based on the total weight of the article.

33. The article of claim 30, wherein the article is an antenna housing.

34. Use of the polymer composition according to any one of claims 1 to 28 in an article.

35. The article of claim 34, wherein the article is an antenna housing.

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