Polypropylene composition with intumescent flame retardant and improved UV stabilization

Abstract

The present invention relates to a polypropylene composition comprising a polymer of propylene, a halogen-free flame retardant containing nitrogen and phosphorus, a pigment and an additive wherein the additive comprises at least one hindered amine light stabilizer (NOR-HALS) comprising a NOR moiety and at least one acid scavenger. Furthermore, the present invention relates to an article comprising the polypropylene composition and to an improvement in the ultraviolet stability of a polypropylene composition comprising a halogen-free flame retardant comprising nitrogen and phosphorus.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a polypropylene composition and to an article comprising the polypropylene composition, and to the improvement of the ultraviolet light (UV) stability of a polypropylene composition comprising a nitrogen- and phosphorus-containing halogen-free flame retardant. BACKGROUND

[0002] When used outdoors, articles composed of polymeric materials have to withstand extreme weather conditions that can occur in some geographical regions. In particular, resistance to ultraviolet light and mechanical stability at temperatures that can vary in a wide range are required. Often, long-term thermal stability, especially at high temperatures, is required. For articles comprising polymeric materials such as polypropylene (PP), this is usually achieved by incorporating ultraviolet light stabilizers, antioxidants and other additives. In addition to this, many applications require that the polymeric material meets certain flammability standards. Therefore, it is common that the polymeric material further comprises a substantial amount of at least one flame retardant. However, it is known that some flame retardants interact with ultraviolet light stabilizers and cause their deterioration. Therefore, there is a need to improve the degree of ultraviolet light stabilization, especially of polypropylene compositions comprising a flame retardant.

[0003] CN106366443B discloses a long glass fiber reinforced polypropylene material comprising a flame retardant, a thermal stabilizer and a lubricant. The material comprises a light stabilizer selected from the group consisting of hindered amine light stabilizers (HALS), salicylate ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers and triazine ultraviolet absorbers. SUMMARY

[0004] The ultraviolet light stability of a polypropylene composition comprising a nitrogen- and phosphorus-containing halogen-free flame retardant is improved by incorporating a specific combination of ultraviolet light stabilizers, namely a combination comprising at least (i) a NOR-HALS and (ii) an acid scavenger. NOR-HALS are also known as amino ether HALS, N-alkoxy HALS or N-hydrocarbyloxy HALS.

[0005] The present disclosure also provides a polypropylene composition having improved ultraviolet light stability and an article comprising the polypropylene composition. DETAILED DESCRIPTION

[0006] The present disclosure provides a polypropylene composition comprising, based on the total amount (100 wt.-%) of the polypropylene composition: (a) 20 wt.-% to 75 wt.-% of a polymer of propylene, (b) 20 wt.-% to 30 wt.-% of a nitrogen- and phosphorus-containing halogen-free flame retardant, (c) 0.2 wt.-% to 2.0 wt.-% of a pigment, and (d) 0.2 wt.-% to 5 wt.-% of an additive, wherein, based on the total amount (100 wt.-%) of the polypropylene composition, the additive (d) comprises: (d1 ) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer comprising a NOR moiety (NOR-HALS), and (d2) 0.1 wt.-% to 1.0 wt.-% of at least one acid scavenger.

[0007] In embodiments, based on the total amount (100 wt.-%) of the polypropylene composition, the polypropylene composition comprises: (a) 20 wt.-% to 75 wt.-% of a polymer of propylene, (b) 20 wt.-% to 30 wt.-% of a halogen-free flame retardant comprising nitrogen and phosphorous, (c) 0.2 wt.-% to 2.0 wt.-% of a pigment, and (d) 0.2 wt.-% to 5.0 wt.-% of an additive, wherein, based on the total amount (100 wt.-%) of the polypropylene composition, the additive (d) comprises: (d1 ) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer comprising a NOR moiety (NOR-HALS), (d2) 0.1 wt.-% to 1.0 wt.-% of at least one acid scavenger, (d3) 0.1 wt.-% to 0.8 wt.-% of at least one UV absorber comprising a phenolic hydroxyl group, (d3) optionally, 0.1 wt.-% to 0.5 wt.-% of at least one antioxidant, and (d4) optionally, 0.1 wt.-% to 0.5 wt.-% of at least one metal deactivator.

[0008] Preferably, the polypropylene composition is a glass fiber reinforced polypropylene composition. In this case, based on the total amount (100 wt.-%) of the polypropylene composition, the polypropylene composition can comprise: (a) 20 wt.-% to 60 wt.-% of a polymer of propylene, (aa) 10 wt.-% to 50 wt.-% of glass fibers, (ab) 1 wt.-% to 5 wt.-% of an adhesion promoter, (b) 20 wt.-% to 30 wt.-% of a nitrogen- and phosphorus-containing halogen-free flame retardant, (c) 0.2 wt.-% to 2.0 wt.-% of a pigment, and (d) 0.2 wt.-% to 5.0 wt.-% of an additive, wherein, based on the total amount (100 wt.-%) of the polypropylene composition, the additive (d) comprises: (d1 ) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer comprising a NOR moiety (NOR-HALS), and (d2) 0.1 wt.-% to 1.0 wt.-% of at least one acid scavenger.

[0009] When the polypropylene composition is a glass fiber reinforced polypropylene composition, the polypropylene (a) preferably has a melt flow rate MFR2 (230 °C) measured according to ISO 1133 of not less than 60 g / 10 min, preferably in the range of 60 g / 10 min to 1000 g / 10 min, more preferably in the range of 60 g / 10 min to 500 g / 10 min, and even more preferably in the range of 60 g / 10 min to 200 g / 10 min.

[0010] In a further preferred embodiment, the polypropylene composition is a glass fiber reinforced polypropylene composition, and based on the total amount (100 wt.-%) of the polypropylene composition, it comprises: (a) 20 wt.-% to 60 wt.-% of a polymer of propylene, (aa) 10 wt.-% to 50 wt.-% of glass fibers, (ab) 1 wt.-% to 5 wt.-% of an adhesion promoter, (b) 20 wt.-% to 30 wt.-% of a nitrogen- and phosphorus-containing halogen-free flame retardant, (c) 0.2 wt.-% to 2.0 wt.-% of a pigment, and (d) 0.2 wt.-% to 5.0 wt.-% of an additive, wherein, based on the total amount (100 wt.-%) of the polypropylene composition, the additive (d) comprises: (d1 ) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer comprising a NOR moiety (NOR-HALS), and (d2) 0.1 wt.-% to 1.0 wt.-% of at least one acid scavenger, (d3) 0.1 wt.-% to 0.8 wt.-% of at least one UV absorber comprising phenolic hydroxyl groups, (d3) optionally, 0.1 wt.-% to 0.5 wt.-% of at least one antioxidant, and (d4) optionally, 0.1 wt.-% to 0.5 wt.-% of at least one metal deactivator.

[0011] Furthermore, the polypropylene composition according to the present application can be a glass fiber reinforced polypropylene composition comprising, based on the total amount (100 wt.-%) of the polypropylene composition: (a) 20 wt.-% to 60 wt.-% of a polymer of propylene, (aa) 10 wt.-% to 50 wt.-% of glass fibers, (ab) 1 wt.-% to 5 wt.-% of an adhesion promoter, (b) 20 wt.-% to 30 wt.-% of a halogen-free flame retardant comprising nitrogen and phosphorous, (c) 1.5 wt.-% to 15 wt.-%, preferably 2.0 wt.-% to 10 wt.-% of a pigment masterbatch, and (d) 0.2 wt.-% to 5.0 wt.-% of additives, wherein the additives (d) comprise, based on the total amount (100 wt.-%) of the polypropylene composition: (d1) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer comprising a NOR moiety (NOR-HALS), (d2) 0.1 wt.-% to 1.0 wt.-% of at least one acid scavenger, (d3) 0.1 wt.-% to 0.8 wt.-% of at least one UV absorber comprising phenolic hydroxyl groups, (d3) optionally, 0.1 wt.-% to 0.5 wt.-% of at least one antioxidant, (d4) optionally, 0.1 wt.-% to 0.5 wt.-% of at least one metal deactivator.

[0012] Polymer of propylene (a) The polypropylene composition of the present disclosure comprises from 20 wt.-% to 75 wt.-%, preferably from 20 wt.-% to 60 wt.-%, even more preferably from 20 wt.-% to 55 wt.-%, most preferably from 30 wt.-% to 50 wt.-% of a polymer of propylene, based on the total amount (100 wt.-%) of the polypropylene composition. In the following, the "polymer of propylene" (a) is also referred to as "polypropylene" (a).

[0013] In a preferred embodiment, the polymer of propylene (a) in the polypropylene composition of the present disclosure is characterized by a melt flow rate MFR2 (230 °C) measured according to ISO 1133 of from 10 g / 10 min to 200 g / 10 min. In the absence of glass fibers in the polypropylene composition, the polymer of propylene preferably has a MFR2 (230 °C) measured according to ISO 1133 of from 10 g / 10 min to 60 g / 10 min, preferably from 15 g / 10 min to 35 g / 10 min. Alternatively, if the polypropylene composition is a glass fiber reinforced polypropylene composition, the polymer of propylene can have a melt flow rate MFR2 (230 °C) measured according to ISO 1133 of not less than 60 g / 10 min, preferably in the range of from 60 g / 10 min to 1000 g / 10 min, more preferably in the range of from 60 g / 10 min to 500 g / 10 min, even more preferably in the range of from 60 g / 10 min to 200 g / 10 min, in particular in the range of from 80 g / 10 min to 150 g / 10 min, such as in the range of from 90 g / 10 min to 120 g / 10 min.

[0014] In a preferred embodiment, the polypropylene (a) is a heterophasic polyolefin composition comprising a matrix (a1) which is a polymer of propylene and an elastomer (a2) which is a copolymer comprising on the one hand units derived from propylene and on the other hand units derived from ethylene and / or an alpha-olefin comprising 4 to 20 carbon atoms, in particular 4 to 10 carbon atoms.

[0015] In the context of the present disclosure, the expression "heterophasic" indicates that the elastomer is (finely) dispersed in the matrix. In other words, the elastomer forms inclusions in the matrix. Thus, the matrix contains (finely) dispersed inclusions which are not part of the matrix and which contain the elastomer. The term "inclusion" is intended to indicate that the matrix and the inclusions form distinct phases within the heterophasic polypropylene. The inclusions are visible, for example, by high resolution microscopy, such as electron microscopy or scanning force microscopy.

[0016] The heterophasic polyolefin composition is generally characterized by a xylene cold soluble (XCS) fraction and a xylene cold insoluble (XCI) fraction. In the context of the present disclosure, the xylene cold soluble (XCS) fraction of the heterophasic polyolefin composition is essentially identical to the elastomer of the heterophasic polyolefin composition.

[0017] Thus, when referring to the intrinsic viscosity and the ethylene content of the elastomer of the heterophasic polyolefin composition, the intrinsic viscosity and the ethylene content of the xylene cold soluble (XCS) fraction of the heterophasic polyolefin composition are meant.

[0018] Thus, the content of the matrix (al) in the polypropylene (a) of the heterophasic polyolefin composition, i.e. the xylene cold insoluble (XCI) content, is preferably in the range of 75.0 wt.-% to 93.0 wt.-%, more preferably in the range of 77.0 wt.-% to 91.0 wt.-%, such as 78.0 wt.-% to 89.0 wt.-%.

[0019] On the other hand, the content of the elastomer (a2) in the polypropylene (a) of the heterophasic polyolefin composition, i.e. the xylene cold soluble (XCS), is preferably in the range of 7.0 wt.-% to 25.0 wt.-%, more preferably in the range of 9.0 wt.-% to 23.0 wt.-%, such as in the range of 11.0 wt.-% to 22.0 wt.-%.

[0020] The polypropylene suitable for use as matrix (al) can include any type of isotactic or predominantly isotactic polypropylene homopolymer or random copolymer known in the art. Thus, the polypropylene can be a propylene homopolymer or an isotactic random copolymer of propylene with ethylene and / or a C4 to C8 a-olefin, e.g. 1-butene, 1-hexene or 1-octene, wherein the total comonomer content is in the range of 0.05 wt.-% to 10 wt.-%.

[0021] Preferably, the polypropylene matrix (al) has a rather high melt flow rate. Thus, it is preferred that in the present application the polypropylene matrix (al), i.e. the xylene cold insoluble (XCI) fraction of the polypropylene (a), has a MFR2 (230 °C) measured according to ISO 1133 in the range of 100.0 g / 10 min to 1500.0 g / 10 min, more preferably in the range of 120.0 g / 10 min to 800.0 g / 10 min, even more preferably in the range of 140.0 g / 10 min to 600.0 g / 10 min, such as in the range of 150.0 g / 10 min to 500.0 g / 10 min.

[0022] Furthermore, the polypropylene matrix (a1 ) can be multimodal or bimodal in terms of molecular weight.

[0023] The expression "multimodal" or "bimodal" used throughout the present disclosure refers to the modality of a polymer, i.e. the form of the molecular weight distribution curve of the polymer, which is a plot of the molecular weight fraction as a function of the molecular weight, and / or the form of the comonomer content distribution curve of the polymer, which is a plot of the comonomer content as a function of the molecular weight of the polymer fraction.

[0024] The elastomer (a2) comprises and preferably consists of units derivable from (i) propylene and (ii) ethylene and / or at least another C4 to C20 a-olefin, such as a C4 to C10 a-olefin. The elastomeric copolymer (E1 ) can additionally contain units derivable from a conjugated diene, such as butadiene, or a non-conjugated diene, however, it is preferred that the elastomeric copolymer consists only of units derivable from (i) propylene and (ii) ethylene and / or a C4 to C20 a-olefin. Suitable non-conjugated dienes, if used, include straight-chain and branched-chain acyclic dienes, such as 1,4-hexadiene, 1,5-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 3,7-dimethyl-1,7-octadiene, and the mixed isomers of dihydromyrcene and dihydrolinolefine, as well as single-ring alicyclic dienes, such as 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,5-cyclododecadiene, 4-vinylcyclohexene, 1 -allyl-4- isopropylidene cyclohexane, 3-allylcyclopentene, 4-cyclohexene and 1 -isopropenyl-4-(4- butenyl)cyclohexane. Multi-ring alicyclic fused and bridged ring dienes are also suitable, including tetrahydroindene, methyltetrahydroindene, dicyclopentadiene, bicyclo(2,2,1)hepta-2,5- diene, 2-methylbicycloheptadiene, and alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbornenes, such as 5-methylene-2-norbornene, 5-isopropylidene norbornene, 5-(4- cyclopentenyl)-2-norbornene and 5-cyclohexylidene-2-norbornene. Preferred non- conjugated dienes are 5-ethylidene-2-norbornene, 1,4-hexadiene and dicyclopentadiene.

[0025] Thus, the elastomer (a2) comprises at least units derivable from propylene and ethylene and can comprise further units derivable from further alpha-olefins as defined in the preceding paragraph. It is preferred that the elastomer (a2) comprises only units derivable from propylene and ethylene and optionally units of a conjugated diene, such as butadiene, or a non-conjugated diene as defined in the preceding paragraph, such as 1,4-hexadiene. Thus, an ethylene propylene non-conjugated diene monomer polymer (EPDM) is especially preferred as elastomer (a2) and an ethylene propylene rubber (EPR) is most preferred.

[0026] As for the matrix (a1), the elastomer (a2) can be unimodal or multimodal, such as bimodal. With regard to the definition of unimodal and multimodal, such as bimodal, reference is made to the above definition.

[0027] In the present disclosure, the content of units derivable from propylene in the elastomer (a2) is equivalent to the content of propylene detectable in the xylene cold soluble (XCS) fraction. Thus, the content of propylene detectable in the xylene cold soluble (XCS) fraction is in the range of 45.0 wt.-% to 75.0 wt.-%, more preferably in the range of 40.0 wt.-% to 70.0 wt.-%. Thus, in a specific embodiment, the elastomer (a2), i.e. the xylene cold soluble (XCS) fraction, comprises 25.0 wt.-% to 65.0 wt.-%, more preferably 30.0 wt.-% to 60.0 wt.-% of units derivable from ethylene. Preferably, the elastomer (a2) is an ethylene propylene non-conjugated diene monomer polymer (EPDM) or an ethylene propylene rubber (EPR), the latter being especially preferred, wherein the propylene and / or ethylene content is as defined in this paragraph.

[0028] A further preference of the present disclosure requires that the intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of the polypropylene as a heterophasic polyolefin composition is rather low. Thus, it is noted that the intrinsic viscosity of the xylene cold soluble (XCS) fraction of the polypropylene as a heterophasic polyolefin composition is below 3.5 dl / g, more preferably not more than 3.4 dl / g. Even more preferred, the intrinsic viscosity of the xylene cold soluble (XCS) fraction of the polypropylene as a heterophasic polyolefin composition is in the range of 1.8 dl / g to 3.5 dl / g, more preferably in the range of 1.9 dl / g to 3.4 dl / g, such as 2.0 dl / g to 3.4 dl / g. The intrinsic viscosity is measured according to ISO 1628 in decalin at 135 °C.

[0029] Preferably, in case the polypropylene (a) is a heterophasic polyolefin composition as defined above, the propylene content in the polypropylene (a) is 85.0 wt.-% to 96.0 wt.-%, more preferably 88.0 wt.-% to 94.0 wt.-%, based on the total weight of the polypropylene (a), more preferably based on the total amount of the matrix (a1 ) and the elastomeric copolymer (a2).

[0030] In an embodiment of the polypropylene composition of the present disclosure, the polymer of propylene (a) is a heterophasic copolymer of propylene. The heterophasic copolymer of propylene can comprise a polypropylene matrix component (a1 ) and an elastomeric propylene copolymer component (a2) dispersed in said polypropylene matrix (a1 ) and comprising units derived from (i) propylene and (ii) ethylene and / or C4 to C20 olefins. Preferably, the heterophasic copolymer of propylene has a melt flow rate MFR2 (230 °C / 2.16 kg) in the range of 60 g / 10 min to 200 g / 10 min, measured according to ISO 1133.

[0031] Examples of suitable polymers of propylene include, but are not limited to, BF970MO and BJ400HP commercially available from Borealis AG, Austria. In addition to the combination of NOR-HALS (d1 ) and acid scavenger (d2), such commercially available products can already include trace amounts (e.g. up to 2.0 wt.-%, more preferably up to 1.0 wt.-%, based on the total amount of the propylene polymer) of one or more additives, such as the additives (d) as defined below.

[0032] Glass fiber (aa) The polypropylene composition of the present disclosure optionally comprises (aa) 10 wt.-% to 50 wt.-% of glass fibers, based on the total amount (100 wt.-%) of the polypropylene composition. In an embodiment, the polypropylene composition comprises 14 wt.-% to 40 wt.-%, preferably 18 wt.-% to 36 wt.-% of glass fibers, based on the total amount (100 wt.-%) of the polypropylene composition.

[0033] Preferably, the glass fibers (aa) are short glass fibers (SGF), preferably chopped glass fibers or chopped strands and / or long glass fibers (LGF), preferably long glass fibers obtained from glass roving. In an embodiment, the glass fibers (aa) are short glass fibers (SGF) or chopped strands. In particular, the glass fibers are short glass fibers (SGF).

[0034] The short glass fibers (SGF), in particular chopped glass fibers or chopped strands, used in the polypropylene composition of the present disclosure can be characterized in that they have an average fiber diameter of 9.0 pm to 15.0 pm, preferably of 10 pm to 13 pm, determined according to ISO 1888:2006(E) method B. In addition, the short glass fibers preferably have an average length (also denoted as “initial average length”) measured before melt blending of the components of the polypropylene composition, which is in the range of 2.0 mm to 10.0 mm, more preferably in the range of 2.3 mm to 9.0 mm, even more preferably in the range of 2.5 mm to 8.0 mm, such as in the range of 3.0 mm to 7.0 mm. The initial average length of the short glass fibers (SGF), in particular chopped glass fibers or chopped strands, is usually provided by the supplier. Furthermore, the weight average fiber length determined according to the FASEP method after injection molding according to the EN ISO 1873-2 standard can be in the range of 0.2 mm to 1.2 mm, more preferably in the range of 0.25 mm to 1.0 mm, even more preferably in the range of 0.3 mm to 0.8 mm. The weight average fiber length and the fiber length distribution are determined according to the FASEP (FAser (German for fiber) SEParation) method on injection molded test specimens prepared according to EN ISO 1873-2. The fibers are separated from the polymer matrix by pyrolysis (625 °C for glass fibers, 500 °C for carbon fibers) in a thermogravimetric analysis (TGA) oven or by solution and physical separation. The separated fibers are suspended in deionized water and the suspension is diluted until the fiber number and fiber overlap are in good balance. The average fiber length is determined by gray scale image processing on FASEP 1.9.44.0 (IDM Systems, Damstadt, Germany) and statistically investigated by calculating the average fiber length and the fiber length distribution. For images of small amounts of fiber clusters and fibers that are cut in any way, accurate results will be achieved. This is achieved by reaching a certain fiber to water fraction. For glass fibers, this fraction should be equal to or lower than 30 mg / L; for carbon fibers, this fraction should be equal to or lower than 20 mg / L. The number of clusters of short fibers should be lower than 20% relative to free fibers, while the number of clusters of long fibers should be lower than 15%. For the evaluation, the FASEP software (ImageProPlus including FASEP module) is used to separate the fibers from the background, to remove dust and other irrelevant features, to separate fibers in overlap situations, and to automatically measure the length of each fiber.

[0035] Preferably, the short glass fibers (SGF), in particular chopped glass fibers or chopped strands, have an initial aspect ratio (measured before melt blending of the components of the polypropylene composition) of 125 to 650, preferably 150 to 500, more preferably 200 to 450. The aspect ratio is the relationship between the average length and the average diameter of the fibers.

[0036] The initial average length and the initial average aspect ratio of the short glass fibers (SGF), in particular chopped glass fibers or chopped strands, refer to the values of the raw material as provided by the supplier.

[0037] In an embodiment of the polypropylene composition of the present disclosure, the glass fibers (aa) are chopped glass fibers having an average fiber diameter of 9.0 pm to 15.0 pm determined according to ISO 1888:2006(E) method B and an initial average length of 3.0 mm to 7.0 mm measured before melt blending of the components of the polypropylene composition.

[0038] An example of suitable glass fibers are 3.5 mm to 4.5 mm chopped E-glass with a diameter of preferably 10 pm to 13 pm. Commercial products are 13 pm chopped E-glass with a 4.0 mm chopped length from Johns Manville Thermoflow CS EC 13636 or 13 pm chopped E-glass with a 4.0 mm chopped length from 3B called 3B-DS2200-13P.

[0039] Adhesion promoter (ab) The polypropylene composition of the present disclosure optionally comprises (ab) 1 wt.% to 5 wt.% of a Adhesion promoter (also denoted as glass fiber compatibilizer). Preferably, the adhesion promoter is only present if the polypropylene composition comprises glass fibers.

[0040] The adhesion promoter (ab) can be any adhesion promoter suitable for polypropylene-based resins. The adhesion promoter is preferably a polar modified polypropylene (PM-PP) homopolymer or copolymer.

[0041] The polar modified polypropylene (PM-PP) homopolymer or copolymer comprises a low molecular weight compound with reactive polar groups. Modified polypropylene homopolymers and copolymers, such as propylene copolymers with ethylene or with other a-olefins (e.g. C4 to C10 a-olefins) are most preferred as they are highly compatible with the polypropylene-based resins of the polypropylene composition of the present disclosure.

[0042] With respect to the structure, the polar modified polypropylene (PM-PP) homo- or copolymer is preferably selected from grafted homo- or copolymers. In this context, it is preferred that the polar modified polypropylene (PM-PP) homo- or copolymer contains groups derived from a polar compound and an ionic compound, the polar compound being in particular selected from the group consisting of anhydrides, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl compounds, oxazolines and epoxides.

[0043] Specific examples of the polar compound are unsaturated cyclic anhydrides and their aliphatic diesters, as well as diacid derivatives. In particular, maleic anhydride and a compound selected from the group consisting of Ci to Cio linear and branched maleic acid dialkyl esters, Ci to Cio linear and branched fumaric acid dialkyl esters, itaconic anhydride, Ci to Cio linear and branched itaconic acid dialkyl esters, acrylic acid, maleic acid, fumaric acid, itaconic acid and mixtures thereof can be used.

[0044] It is particularly preferred to use a polypropylene homo- or copolymer grafted with maleic anhydride or acrylic acid as the polar modified polypropylene (PM-PP) homo- or copolymer, i.e. the adhesion promoter (ab).

[0045] The modified polymer, i.e. the adhesion promoter (ab), can be produced in a simple manner, for example, as disclosed in US 4,506,056, US 4,753,997 or EP 1 805 238, by reactive extrusion of the polymer with maleic anhydride or acrylic acid in the presence of a free radical generator, such as an organic peroxide.

[0046] The preferred amount of groups derived from a polar compound in the polar modified polypropylene (PM-PP) homo- or copolymer, i.e. the adhesion promoter, is in the range of 0.5 wt.-% to 5.0 wt.-%. For example, the amount can be in the range of 0.5 wt.-% to 4.5 wt.-%, preferably in the range of 0.5 wt.-% to 4.0 wt.-%, more preferably in the range of 0.5 wt.-% to 3.5 wt.-%.

[0047] The polar modified polypropylene (PM-PP) homo- or copolymer, i.e. the adhesion promoter, has a melt flow rate MFR2(230 °C, 2.16 kg) in the range of 20.0 g / 10 min to 400 g / 10 min. It is particularly preferred that the polar modified polypropylene (PM-PP) homo- or copolymer has a melt flow rate MFR2(230 °C, 2.16 kg) in the range of 40.0 g / 10 min to 300 g / 10 min, more preferably in the range of 50.0 g / 10 min to 250 g / 10 min.

[0048] In embodiments of the present disclosure, the adhesion promoter (ab) is a maleic anhydride modified polypropylene homopolymer or copolymer and / or an acrylic acid modified polypropylene homopolymer or copolymer. Preferably, the adhesion promoter is a maleic anhydride modified polypropylene homopolymer and / or an acrylic acid modified polypropylene homopolymer, and preferably a maleic anhydride modified polypropylene homopolymer. For example, suitable polar modified polypropylene (PM-PP) homopolymers or copolymers include, for example, polypropylene homopolymers grafted with maleic anhydride (PP-g-MAH) and polypropylene homopolymers grafted with acrylic acid (PP-g-AA).

[0049] The adhesion promoter is preferably present in an amount of 1 wt.-% to 5 wt.-%, more preferably 1 wt.-% to 4 wt.-%, most preferably 1 wt.-% to 3 wt.-%, based on the total weight of the respective polypropylene composition.

[0050] Halogen-free flame retardant containing nitrogen and phosphorus (HFFR) (b) The polypropylene composition of the present disclosure comprises (b) 20 wt.-% to 30 wt.-% of a nitrogen and phosphorus containing halogen-free flame retardant, based on the total amount (100 wt.-%) of the polypropylene composition. In preferred embodiments, the polypropylene composition comprises 20 wt.-% to 28 wt.-%, preferably 21 wt.-% to 26 wt.-% of a nitrogen and phosphorus containing halogen-free flame retardant. Using these amounts of the nitrogen and phosphorus containing halogen-free flame retardant, the polypropylene composition easily achieves a V0 rating.

[0051] The flame retardant (b) is free of halogen. In other words, it is preferred that the flame retardant (b) does not contain any organic or inorganic compound containing halogen atoms. As used herein, the term "halogen" refers to the elements of group 17 of the periodic table. Furthermore, the flame retardant (b) is a N, P based halogen-free flame retardant. This means that it is a halogen-free flame retardant preferably having at least one nitrogen containing moiety and at least one phosphorus containing moiety. The at least one nitrogen containing moiety is preferably selected from the group consisting of ammonium, piperazine, melamine, diamine, amide and derivatives and combinations thereof. The at least one phosphorus containing moiety is preferably selected from the group consisting of phosphate salts (e.g. orthophosphate, diphosphate, polyphosphate or pyrophosphate), phosphoric acid, polyphosphoric acid, phosphinic acid, phosphorus pentoxide and derivatives and combinations thereof.

[0052] It is further preferred that the flame retardant (b) is an intumescent flame retardant.

[0053] In embodiments, the halogen-free flame retardant (b) can comprise at least one nitrogen containing phosphate salt, preferably at least one organic nitrogen containing phosphate salt. Preferably, the organic nitrogen containing phosphate salt is a phosphate salt of a heterocyclic C3-C6- (more preferably C3-C4-) alkyl or aryl compound comprising at least one N atom.

[0054] In some embodiments, the halogen-free flame retardant (b) is or comprises ammonium polyphosphate. Suitable halogen-free flame retardants (b) are commercially available, for example, Budit 699S from Budensheim, Presafer products: 100A, 100C and 100D.

[0055] Other suitable halogen-free flame retardants (b) include ADK STAB FP-2100JC, ADK STAB FP-2500S, ADK STAB FP-2600U from ADEKA and PNA220 from JLS Chemicals.

[0056] In most commercial products, the nitrogen content is in the range of 18 wt.-% to 35 wt.-%, while the phosphorous content is in the range of 16 wt.-% to 25 wt.-%.

[0057] According to a particular embodiment of the present disclosure, the halogen-free flame retardant (b) comprises a first nitrogen-containing phosphate salt (P1) and a second nitrogen-containing phosphate salt (P2) different from the first nitrogen-containing phosphate salt (P1).

[0058] In this particular embodiment, the first nitrogen-containing phosphate salt (P1) and the second nitrogen-containing phosphate salt (P2) can be organic nitrogen-containing phosphate salts. It is especially preferred that the first nitrogen-containing phosphate salt (P1) and the second nitrogen-containing phosphate salt (P2) are phosphate salts of heterocyclic C3-C6- (more preferably C3-C4-) alkyl or aryl compounds comprising at least one N atom.

[0059] It is preferred that the first nitrogen-containing phosphate salt (P1) is an organic nitrogen-containing polyphosphate salt. More preferably, the first nitrogen-containing phosphate salt (P1) is a polyphosphate salt of heterocyclic C3-C6- (more preferably C3-C4-) aryl compounds comprising at least one N atom. It is especially preferred that the first nitrogen-containing phosphate salt (P1) is melamine polyphosphate.

[0060] It is preferred that the second nitrogen-containing phosphate salt (P2) is an organic nitrogen-containing diphosphate salt. More preferably, the second nitrogen-containing phosphate salt (P2) is a diphosphate salt of heterocyclic C3-C6- (more preferably C3-C4-) alkyl compounds comprising at least one N atom (such as two N atoms). It is especially preferred that the second nitrogen-containing phosphate salt (P2) is piperazine pyrophosphate.

[0061] According to a preferred embodiment of the present disclosure, the weight ratio between the first nitrogen-containing phosphate salt (P1) and the second nitrogen-containing phosphate salt (P2) is in the range of 70:30 to 30:70.

[0062] A highly suitable example of a commercially available halogen-free flame retardant (b) according to the specific embodiments described above is Phlamoon, manufactured and supplied by SULI. ® -1090A is a flame retardant product sold under a trademark.

[0063] The amount of halogen-free flame retardant (b) refers to the amount of halogen-free flame retardant (b) supplied by the manufacturer of halogen-free flame retardant (b) based on the total weight of the polypropylene composition. Therefore, halogen-free flame retardant (b) may contain trace amounts of other components, such as additives, flame retardant synergists, and / or carrier media. It should be understood that such other components are included in the amount of halogen-free flame retardant (b).

[0064] In the embodiments, based on the total amount (100 wt.-%) of the halogen-free flame retardant (b), the halogen-free flame retardant (b) comprises 35 wt.-% to 40 wt.-% of melamine polyphosphate and 50 wt.-% to 60 wt.-% of piperazine pyrophosphate.

[0065] Pigment (c) The polypropylene composition disclosed herein comprises (c) 0.2 wt.-% to 2.0 wt.-% of pigment based on the total amount (100 wt.-%) of the polypropylene composition. Preferably, the polypropylene composition comprises 0.3 wt.-% to 1.5 wt.-% of pigment based on the total amount (100 wt.-%) of the polypropylene composition, particularly 0.4 wt.-% to 1.3 wt.-% of pigment.

[0066] To provide the pigment content as defined above, the pigment is preferably incorporated into the polypropylene composition in the form of a pigment masterbatch. The pigment masterbatch preferably comprises a pigment and at least one pigment carrier polymer. In embodiments, the pigment carrier polymer may be a propylene homopolymer or copolymer.

[0067] The pigment can be an organic pigment and / or carbon black. When the pigment is an organic pigment, it is preferably a phthalocyanine pigment. For example, when the pigment is an organic pigment, it can be selected from phthalocyanine green pigment, phthalocyanine blue pigment, and combinations thereof.

[0068] Additive (d) The polypropylene composition of the present disclosure comprises (d) 0.2 wt.-% to 5.0 wt.-% of an additive, based on the total amount of the polypropylene composition (100 wt.-%). In some embodiments, the polypropylene composition of the present disclosure can comprise (d) 0.25 wt.-% to 2.50 wt.-%, preferably 0.5 wt.-% to 2.0 wt.-% of an additive, based on the total amount of the polypropylene composition (100 wt.-%). Within the terms of the present disclosure, an additive is all compounds which are included in an amount equal to or less than 5 wt.-%, based on the total amount of the polypropylene composition (100 wt.-%) and in addition to adhesion promoters, pigments and / or pigment carrier polymers.

[0069] NOR-HALS (d1) The polypropylene composition of the present disclosure comprises (d1) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer HALS comprising a NOR moiety, based on the total amount of the polypropylene composition (100 wt.-%).

[0070] The hindered amine light stabilizer (d1) is present in an amount of 0.1 wt.-% to 1.0 wt.-%, based on the total amount of the polypropylene composition (100 wt.-%), for example, the hindered amine light stabilizer (d1) is present in an amount of 0.2 wt.-% to 1.0 wt.-%, 0.3 wt.-% to 0.8 wt.-% or 0.4 wt.-% to 0.7 wt.-%.

[0071] The hindered amine light stabilizer (HALS) comprises a NOR moiety (NOR-HALS). The NOR moiety is preferably a moiety comprising an alkoxy substituent on the nitrogen atom of a heterocyclic moiety. In embodiments, the residue R in the NOR moiety is an alkyl or cycloalkyl N-alkoxy moiety. Furthermore, the NOR-HALS can comprise at least one 2,2,6,6-substituted piperidine moiety or at least one 2,2-substituted piperazine moiety. In embodiments, the NOR-HALS comprises at least two 2,2,6,6-substituted piperidine moieties. Preferably, the NOR-HALS comprises more than two 2,2,6,6-substituted piperidine moieties.

[0072] In the present context, “2,2,6,6-substituted” and “2,2-substituted” refer to a piperidine moiety or a piperazine moiety, respectively, which carries a substituent at least at the indicated position and which can also comprise substituents in other positions as is well known in the art of hindered amine light stabilizers.

[0073] NOR-HALS(d1) preferably comprises at least one piperidine moiety with a substituent at positions 2, 2, 6, 6, wherein the substituent is selected from one or more of the following groups: (C1-C6) alkyl groups and cyclic groups selected from saturated (C5-C6) cyclic groups and (C5-C6) aromatic cyclic groups, wherein the saturated (C5-C6) cyclic group has a carbon atom and optionally has one or two heteroatoms selected from nitrogen (N) and oxygen (O); NOR-HALS(d1) preferably comprises at least one piperidine moiety with a substituent at positions 2, 2, 6, 6, wherein the substituent is selected from one or more (C1-C6) alkyl groups, preferably selected from one or more (C1-C3) alkyl groups.

[0074] In the examples, NOR-HALS(d1) is a polymeric hindered amine compound. As used herein, "polymeric hindered amine compound" means a hindered amine compound having two or more piperidine moieties containing repeating units with substituents at at least the 2,2,6,6-positions.

[0075] Preferably, NOR-HALS(d1) has a weight-average molecular weight M of at least 400 g / mol. w However, a particularly preferred option is the high molecular weight NOR-HALS(d1) with a weight-average molecular weight M. w It is 2,000 g / mol or above, for example, 2,000 g / mol to 7,000 g / mol, such as 2,000 g / mol to 5,000 g / mol, or 2,500 g / mol to 4,500 g / mol.

[0076] The NOR-HALS(d1) disclosed herein is commercially available and supplied, for example, by BASF, Sigma-Aldrich, Ciba and Cytec.

[0077] Suitable examples of NOR-HALS include Tinuvin ® NOR 356 FF (CAS: 1902936-62-2), Tinuvin ® NOR371 (CAS:247243-62-5) and Flamesterab NOR 116 (CAS:191680-81-6). Other suitable examples include NOR LA81 (CAS:705257-84-7) and NOR123 (CAS:129757-67-1).

[0078] In particular embodiments, the NOR-HALS is selected from l,3,5-triazine-2,4,6-triamine, N2,N2'-l,6-hexanediylbis[N4,N6-dibutylN2,N4,N6-tris(2,2,6,6-tetramethyl-4-piperidinyl)-N-allyl derivates, oxidized, hydrogenated] (available as Tinuvin® 292, BASF Corporation, CAS No. 68917- 01-7). ® NOR 356 FF, CAS No. 1902936-62-2).

[0079] Acid scavenger (d2) The polypropylene composition of the present disclosure comprises (d2) 0.1 wt.-% to 1.0 wt.-%, based on the total amount of the polypropylene composition (100 wt.-%), of at least one acid scavenger.

[0080] Suitable acid scavengers (d2) include hydrotalcite, zinc oxide, and C11 to C20 alkyl carboxylate salts (e.g., stearate salts). In embodiments, the acid scavenger (d2) includes at least one stearate salt selected from the group consisting of magnesium stearate, calcium stearate, strontium stearate, barium stearate, and zinc stearate. In particular embodiments, the acid scavenger (d2) is calcium stearate (CAS: 1592-23-0).

[0081] Ultraviolet absorber comprising phenolic hydroxyl groups (d3) The polypropylene composition of the present disclosure optionally comprises (d3) 0.1 wt.-% to 0.8 wt.-%, based on the total amount of the polypropylene composition (100 wt.-%), of at least one ultraviolet light absorber comprising phenolic hydroxyl groups. Preferably, the polypropylene composition comprises 0.2 wt.-% to 0.7 wt.-%, based on the total amount of the polypropylene composition (100 wt.-%), of at least one ultraviolet light absorber comprising phenolic hydroxyl groups.

[0082] In particular embodiments, the at least one UV absorber comprising a phenolic hydroxyl group (d3) is selected from the group consisting of 2-hydroxy-4-n-octoxybenzophenone (CAS: 1843-05-6), 2-(4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(octyloxy)-phenol (CAS: 2725-22-6) and hexadecyl-3,5-bis-tert-butyl-4-hydroxybenzoate (CAS: 67845-93-6).

[0083] Antioxidant (d4) The polypropylene composition of the present disclosure optionally comprises (d4) 0.1 wt.-% to 0.5 wt.-% of at least one antioxidant, based on the total amount (100 wt.-%) of the polypropylene composition. In preferred embodiments, the polypropylene composition comprises 0.2 wt.-% to 0.4 wt.-% of at least one antioxidant, based on the total amount (100 wt.-%) of the polypropylene composition.

[0084] In preferred embodiments, the at least one antioxidant (d4) is selected from the group consisting of phenolic antioxidants and phosphorous-containing antioxidants. In particular, the at least one antioxidant (d4) can be selected from the group consisting of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (CAS: 2082-79-3), 2,6-di-tert-butyl-4-methylphenol (CAS: 128-37-0), pentaerythrityl-tetrakis(3-(3',5'-di-tert-butyl-4-hydroxyphenyl)-propionate) (CAS: 6683-19-8), bis(2,4-di-tert-butylphenyl)pentaerythrityl-diphosphite (CAS: 26741-53-7) and tris(2,4-di-tert-butylphenyl)-phosphite (CAS: 31570-04-4). Among these, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (CAS: 2082-79-3) and tris(2,4-di-tert-butylphenyl)-phosphite (CAS: 31570-04-4) are particularly preferred antioxidants (d4).

[0085] In another embodiment, the antioxidant (d4) is a di(C8-C30)alkyl amine compound, optionally with another substituent, such as a long chain N,N-dialkyl hydroxylamine compound of the formula R1R2NOH (I), wherein R1and R2are independently selected from alkyl groups having 8 to 30 carbon atoms. In embodiments, the antioxidant (d4) is a di((C10-C25)alkyl)hydroxylamine compound, preferably a di((C15-C22)alkyl)hydroxylamine compound.

[0086] A suitable example of the antioxidant (d4) of the present application is bis(octadecyl)hydroxylamine (CAS No.: 143925-92-2).

[0087] The antioxidant (d4) of the present application is commercially available and, for example, supplied by BASF and Sigma-Aldrich.

[0088] Metal deactivator (d5) The polypropylene composition of the present disclosure optionally comprises (d5) 0.1 wt.-% to 0.5 wt.-%, based on the total amount (100 wt.-%) of the polypropylene composition, of at least one metal deactivator. The metal deactivator can be an organometallic deactivator. The metal deactivator preferably exerts its effect by passivating metal ions which can be introduced into the polypropylene composition by talc and / or other additives.

[0089] Thus, in the broadest sense, an organometallic deactivator is a complexing agent which is capable of passivating or reducing the ability of metal ions, such as iron ions or copper ions, to initiate or catalyze the partial degradation of additives in a polymer or polymer composition (IUPAC, 1996). It is therefore preferred that the organometallic deactivator comprises at least one, preferably two, -C(O)-NH- groups.

[0090] Examples of organometallic passivators are 2,2'-Oxamidobis-(ethyl-3-(3,5-di-tert-butyl-4- hydroxyphenyl)-propionate) (CAS: 70331-94-1), N,N'-Bis(3-(3',5'-di-tert-butyl-4'- hydroxyphenyl)propionyl)hydrazine (CAS: 32687-78-8), Oxamidyl-bis-(benzylidenehydrazine) (CAS: 6629-10-3), 2,5-Bis-(2-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamido)ethylamino)- benzoquinone, Tris-(2-tert-butyl-4-thio-(2'-methyl-4'-hydroxy-5'-tert-butyl)phenyl-5-methyl)- phenylphosphite (CAS: 36339-47-6) and Decamethylene-dicarboxy-dihydroxyaline (CAS: 63245-38-5). Especially preferred organometallic passivators are N,N'-Bis(3-(3',5'-di-tert-butyl-4'- hydroxyphenyl)propionyl)hydrazine (CAS: 32687-78-8) and / or 2,2'-Oxamidobis-(ethyl-3-(3,5-di-tert- butyl-4-hydroxyphenyl)-propionate) (CAS: 70331-94-1).

[0091] In a particular embodiment, the metal passivator (d5) is 2,2'-Oxamidobis-(ethyl-3-(3,5-di-tert- butyl-4-hydroxyphenyl)-propionate) (CAS: 70331-94-1).

[0092] Hindered amine light stabilizer without NOR moiety (Non-NOR HALS) (d6) The polypropylene composition of the present disclosure can further comprise at least one (d6) hindered amine light stabilizer (non-NOR HALS) not containing a NOR moiety, preferably in an amount of 0.05 wt.-% to 0.5 wt.-%, based on the total amount (100 wt.-%) of the polypropylene composition.

[0093] The non-NOR-HALS can be one ester comprising a tetramethylpiperidine moiety (also denoted as "ester-HALS") or a combination of two or more esters comprising a tetramethylpiperidine moiety. Preferably, the non-NOR-HALS is selected from the group consisting of tetramethylpiperidine fatty acid esters, preferably C11 to C18 tetramethylpiperidine fatty acid esters, in particular C16 to C18 tetramethylpiperidine fatty acid esters (available as CAS: 86403-32-9 / 167078-06-0); and polymers comprising tetramethyl-1-piperidine ethanol repeat units with alpha, omega-dicarboxylic acid repeat units (available as CAS: 65447-77-0) and combinations thereof.

[0094] Nucleating agent (d7) The polypropylene composition of the present disclosure can further comprise (d7) 0.1 wt.-% to 1.2 wt.-%, preferably 0.25 wt.-% to 1.0 wt.-%, based on the total amount (100 wt.-%) of the polypropylene composition, of a nucleating agent.

[0095] In a preferred embodiment, the nucleating agent can be an inorganic nucleating agent, for example a mineral nucleating agent. For example, the nucleating agent can comprise or consist of a IUPAC group 2 metal compound, such as calcium carbonate or talc.

[0096] The term "talc" as used according to the present invention refers to a relatively wide range of natural minerals having a high magnesium silicate content (e.g. corresponding to more than about 90 wt.-% of MgO + SiO2). Although talc having a small particle size and a uniform particle size distribution is preferred, it is believed that most commercial talc grades are also suitable for the use according to the present invention.

[0097] Article The present disclosure further provides an article comprising the polypropylene composition of the present disclosure.

[0098] In particular, the present disclosure relates to an article comprising at least 60 wt.-%, more preferably at least 80 wt.-%, yet more preferably at least 90 wt.-%, such as at least 95 wt.-% or at least 99 wt.-%, of the polypropylene composition of the present disclosure. In an especially preferred embodiment, the present disclosure relates to an article consisting of the polypropylene composition of the present disclosure.

[0099] The article is preferably an automotive article, such as an automotive article in the field of electronic components, such as electric cable insulation, housings of electrical equipment, containers, and parts of power electronic components in automotive parts and home appliance parts, etc.

[0100] In embodiments, the article of the present disclosure forms part of or consists of an electric cable insulation, such as a battery housing, a housing of electrical equipment, a container, or a power electronic component of an automobile or a home appliance.

[0101] Use The present disclosure also relates to the use of a NOR-HALS and an acid scavenger for improving the UV stability of a polypropylene composition comprising halogen-free flame retardants containing nitrogen and phosphorous. In embodiments, the aforementioned combination of compounds is used in a polypropylene composition additionally comprising an organic pigment, e.g. a phthalocyanine pigment. If the combination of NOR-HALS and acid scavenger is used for the UV stabilization of a polypropylene composition reinforced with glass fibers, i.e. the polypropylene composition additionally comprises glass fibers and an adhesion promoter, a significant improvement is shown. Likewise, if the combination of NOR-HALS and acid scavenger is used for the UV stabilization of a polypropylene composition additionally comprising at least one UV absorber comprising phenolic hydroxyl groups, a good effect is observed.

[0102] In some embodiments, the NOR-HALS (i) is selected from oxidized, hydrogenated 1,3,5-triazine-2,4,6-triamine, N2,N2'-1,6-hexanediylbis[N4,N6-dibutyl-N2,N4,N6-tris(2,2,6,6-tetramethyl-4-piperidinyl)-N-allyl derivates (CAS No.: 1902936-62-2).

[0103] In some embodiments, the acid scavenger (ii) is selected from hydrotalcite, zinc oxide and C11 to C20 alkyl carboxylates, e.g. stearates. In some embodiments, the acid scavenger (ii) comprises at least one stearate selected from the group consisting of magnesium stearate, calcium stearate, strontium stearate, barium stearate and zinc stearate. In a particular embodiment, the acid scavenger (ii) is calcium stearate (CAS: 1592-23-0).

[0104] In a particular embodiment, the combination of (i) oxidized, hydrogenated 1,3,5-triazine-2,4,6-triamine, N2,N2'-1,6-hexanediylbis[N4,N6-dibutyl-N2,N4,N6-tris(2,2,6,6-tetramethyl-4-piperidinyl), -N-allyl derivates, oxidized, hydrogenated (CAS No.: 1902936-62-2) and (ii) calcium stearate (CAS: 1592-23-0) is employed.

[0105] Examples A density of 908 kg / m3 3a melt flow rate (230 °C, 2.16 kg) of 100 g / 10 min (measured according to ISO 1133), a flexural modulus (2 mm / min) of 1.500 MPa (measured according to ISO 178), a tensile strength (50 mm / min) of 28 MPa (measured according to ISO 527-2), a heat distortion temperature (0.45 MPa) of 95 °C (measured according to ISO 75-2), a notched Charpy impact strength (23 °C) of 4 kJ / m 2 a notched Charpy impact strength (23 °C) of 4 kJ / m 2 A series of polypropylene compositions was produced with the low viscosity polypropylene compound (BJ400HP, Borealis AG) as base polymer.

[0106] For all formulations, the amount of NOR-HALS (NOR356) was kept constant, while the calcium stearate concentration (CE vs. IE1-5) and the type and amount of UV absorber (in IE1-5), optionally in a carrier propylene polymer, was varied according to Table 1 below. All formulations contained 30 wt.-% glass fibers (SGF, 13 pm chopped E glass with 4.0 mm chop length from Johns Manville Thermoflow CS EC 13636), 22.5 wt.-% intumescent flame retardant (Phlamoon ® 1090A), 1.5 wt.-% adhesion promoter (PP grafted with maleic anhydride, SCONA TPPP8112 GA), 0.1 wt.-% AO1, 0.14 wt.-% AO2, 0.3 wt.-% MD1, 3 wt.-% phthalocyanine green pigment concentrate (pigment loading 14 wt.-%, supplied by Audia Liqui Kolor), and the remainder to 100 wt.-%, which was the polypropylene compound BJ400HP. The results are listed in Table 1 below.

[0107] A series of comparative polypropylene compositions was produced, the results of which are shown in Table 2 below. Comparative compositions CE2 to CE4 were likewise produced with a low viscosity polypropylene compound (BJ400HP, Borealis AG) as base polymer, which had a density of 908 kg / m3(measured according to ISO 1183), a melt flow rate (230°C, 2.16 kg) of 100 g / 10 min (measured according to ISO 1133), a flexural modulus (2 mm / min) of 1.500 MPa (measured according to ISO 178), a tensile strength (50 mm / min) of 28 MPa (measured according to ISO 527-2), a heat distortion temperature (0.45 MPa) of 95°C (measured according to ISO 75-2), a notched Charpy impact strength (23°C) of 4 kJ / m2(measured according to ISO 179 / 1 eA) and a notched Charpy impact strength (-20°C) of 2 kJ / m2(measured according to ISO 179 / 1 eA).

[0108] For all formulations, the amount of non-NOR-HALS (HALS1) was kept constant, while the calcium stearate concentration (inventive examples vs. comparative examples) and the type of UV absorber were varied according to Table 2 below. All formulations contained 30 wt.-% glass fibers (SGF, 13 pm chopped E glass with 4.0 mm chop length from Johns Manville Thermoflow CS EC 13636), 22.5 wt.-% intumescent flame retardant (Phlamoon® 1090A), 1.5 wt.-% adhesion promoter (PP grafted with maleic anhydride, SCONA TPPP 8112 GA), 0.1 wt.-% AO1, 0.1 wt.-% AO2, 0.3 wt.-% MD1, 3 wt.-% phthalocyanine-based green pigment concentrate (pigment loading of 14 wt.-%, supplied by Audia Liqui Kolor), and the remainder to 100 wt.-%, which was the polypropylene compound BJ400HP.

[0109] Additives used in the formulations Antioxidant

[0110] AO1 (Irganox ® 1076) CAS: 2082-79-3, M w for 531 g / mol, T m of 50-55°C

[0111] AO2 (Irgafos 168) CAS: 31570-04-4, M ® 168) CAS: 31570-04-4, M w for 647 g / mol, T m 182-186°C Metal deactivator

[0112] MD1 (PALMAROLE MDA.P.10) CAS: 32687-78-8, M w for 553 g / mol, T m 224-229°C NOR-HALS Oxidized, hydrogenated 1,3,5-triazine-2,4,6-triamine, N2,N2'-1,6-hexanediylbis[N4,N6-dibutyl-N2,N4,N6-tris(2,2,6,6-tetramethyl-4-piperidyl)-, N-allyl derivative (content (W / W): 100%) NOR356 CAS: 1902936-62-2, decomposes without melting at > 285°C (Tg = 105°C) HALS

[0113] HALS1 (Tinuvin 770) CAS: 65447-77-0, M ® 622) CAS: 65447-77-0, M w > 2.500 g / mol, T m 55-70°C

[0114] (wherein R is C11-C18, predominantly C16-C18) HALS2 CAS: 86403-32-9 / 167078-06-0, M w for 409 g / mol, T m 28-32°C Ultraviolet absorber

[0115] UVa1 (Chimassorb 81) CAS: 1843-05-6, M ® 81) CAS: 1843-05-6, M w for 326 g / mol, Tm 47-49°C

[0116] UVa2 (Tinuvin ® 1164), CAS: 2725-22-6, M w w 509 g / mol, T m is 88-91 °C

[0117] UVa3 CAS: 67845-93-6, M w w 475 g / mol, T m >58 °C Acid scavenger

[0118] CaSt CAS: 1592-23-0, M w w 607 g / mol, T m is 145-160 °C Flame retardant

[0119] The obtained polypropylene compositions were subjected to UV weathering under humid (Florida) and dry (Kalahari) UV aging conditions. The color change due to the respective UV aging conditions was measured. In addition, the flammability of the polypropylene compositions has been checked according to the UL-94 standard. The results of those tests are summarized in Table 1 In all cases, an improvement in UV resistance was observed. Under Kalahari conditions, a significant improvement in UV weathering was found when calcium stearate was used in an amount of 0.5 wt.-%.

[0120] Florida UV aging conditions (PV 3930):

[0121] The irradiance was 60 W / m 2 (300-400 nm), the black standard temperature was 65 ± 2 °C, the chamber temperature was 38 ± 3 °C, the relative humidity was 70 %, the ratio of rain cycle to UV cycle = 18 min / 102 min.

[0122] PV 3930 is a test method developed by Volkswagen Ag, which describes an accelerated weathering method relying on the use of xenon arc lamps as illumination source in order to characterize the aging behavior of plastics, elastomers and convertible top cloth. This guideline relies on the guidelines of ASTM G155 and ISO 4892-2.

[0123] Kalahari UV weathering conditions (PV 3929): irradiance of 75 W / m 2 (300-400 nm), black standard temperature of 90 ± 2 °C, chamber temperature of 50 ± 2 °C, relative humidity of 20%, no rain cycle.

[0124] PV 3929 is a test method developed by Volkswagen Ag, which describes an accelerated weathering method relying on the use of a xenon arc lamp as an illumination source in order to characterize the aging behavior of plastics, elastomers and folding roof cloth. This guideline relies on the ASTM G155 guideline.

[0125] Color change

[0126] Color change is assessed by the CIELAB color space, such as the following attributes, as defined by the International Commission on Illumination (CIE) in 1994: DL*, the difference in lightness / darkness value, where a positive value indicates a shift towards a lighter color and a negative value indicates a shift towards a darker color; Da*, the difference on the red / green axis, where a positive value indicates a shift towards a reddish color and a negative value indicates a shift towards a greenish color; Db*, the difference on the yellow / blue axis, where a positive value indicates a shift towards a yellowish color and a negative value indicates a shift towards a bluish color; and / or DE*, the total color difference value. Color measurements are performed with a DATACOLOR DC 500 colorimeter and according to DIN EN ISO 11664-4.

[0127] UL-94 UL94 vertical burning tests are performed according to UL 94: 2016.

[0128] Generally, UL 94:2016 requires the formulation to be injection molded into samples having a length of 125 ± 5 mm, a width of 13.0 ± 0.5 mm and a thickness of 0.8 to 3.2 mm. Under Condition Part 1, the samples must be conditioned at a constant room temperature of 23 ± 2 °C and a humidity of 50 ± 10% for 48 hours. Under Condition Part 2, the samples must be conditioned in an air circulating oven at 70 ± 1 °C for 168 hours and then cooled in a desiccator at room temperature for at least 4 hours before testing. The test must be performed within 30 minutes of removing the sample from the conditioning environment. The sample is suspended vertically in the test chamber and the sample is subjected to a first ignition for 10 seconds and then a second ignition for 10 seconds. The burning time after each ignition is recorded, it is also noted whether there is afterglow, whether there are burning drips that ignite the cotton at the bottom of the chamber, and whether the flame or glow spreads to the clamping jaws. The classification is V-0, V-1, V-2 or no classification. It is worth noting that the classification depends on the thickness of the sample.

[0129] In the following, the UL94 vertical burning test is performed only under the above Condition Part 1, i.e. the samples are conditioned at a constant room temperature of 23 ± 2 °C and a humidity of 50 ± 10% for 48 hours. The samples have a thickness of 1.5 mm. Table 1

[0130] n. d. - not determined CE = comparative example IE = inventive example + Blend 1 = blend of UVa3 (25 wt.-%) and HALS2 (25 wt.-%) in the carrier propylene polymer ++ Mixture of UVa1 and UVa2 in a weight ratio of 1 : 1 Table 2

[0131] n. d. - not determined.

Claims

1. A polypropylene composition, characterized in that, Based on the total amount of the polypropylene composition, the polypropylene composition comprises: (a) Polymers of propylene ranging from 20 wt.% to 75 wt.% (b) 20 wt.% to 30 wt.% of nitrogen- and phosphorus-containing halogen-free flame retardants, (c) 0.2 wt.% to 2.0 wt.% of pigments, and (d) 0.2 wt.% to 5 wt.% of additives, Wherein, based on the total amount of the polypropylene composition, the additive (d) comprises: (d1) 0.1 wt.-% to 1.0 wt.-% of at least one hindered amine light stabilizer comprising the NOR moiety (NOR-HALS), and (d2) At least one acid scavenger, ranging from 0.1 wt.% to 1.0 wt.%.

2. The polypropylene composition according to claim 1, characterized in that, (a) The polymer of propylene is a multiphase copolymer of propylene, preferably a multiphase copolymer of propylene comprising the following components: Polypropylene matrix component (a1), and Elastomer propylene copolymer component (a2), said elastomeric propylene copolymer component (a2) is dispersed in the polypropylene matrix (a1) and includes units derived from (i) propylene and (ii) ethylene and / or C4 to C20 olefins.

3. The polypropylene composition according to claim 1 or 2, characterized in that, (a) The polymer of propylene is a multiphase copolymer of propylene having a melt flow rate MFR2 (230°C / 2.16 kg) in the range of 10 g / 10 min to 200 g / 10 min, preferably in the range of 60 g / 10 min to 200 g / 10 min, as measured according to ISO 1133.

4. The polypropylene composition according to any one of claims 1 to 3, characterized in that, The polypropylene composition further comprises: (aa) 10 wt.-% to 50 wt.-% of glass fiber based on the total amount of the polypropylene composition, preferably, the glass fiber is short glass fiber with an average fiber diameter of 9 μm to 15 μm. The average fiber diameter was determined according to ISO 1888:2006(E) Method B.

5. The polypropylene composition according to claim 4, characterized in that, The polypropylene composition further comprises: (ab) 1 wt.-% to 5 wt.-% of the total amount of the polypropylene composition, wherein the adhesive accelerator is a polypropylene homopolymer or polypropylene copolymer grafted with maleic anhydride.

6. The polypropylene composition according to any one of claims 1 to 5, characterized in that, (b) The nitrogen- and phosphorus-containing halogen-free flame retardant has at least one nitrogen-containing portion and at least one phosphorus-containing portion. The at least one nitrogen-containing moiety is preferably selected from the group consisting of ammonium, piperazine, melamine, diamine, amide and its derivatives and combinations thereof, and / or The at least one phosphorus-containing component is preferably selected from the group consisting of phosphate, phosphoric acid, polyphosphoric acid, phosphonic acid, phosphorus pentoxide and its derivatives and combinations thereof, wherein the phosphate is, for example, orthophosphate, diphosphate, polyphosphate or pyrophosphate.

7. The polypropylene composition according to any one of claims 1 to 6, characterized in that, (b) The nitrogen and phosphorus-containing halogen-free flame retardant comprises 35 wt.-% to 40 wt.-% of melamine polyphosphate and 50 wt.-% to 60 wt.-% of piperazine pyrophosphate based on the total amount of the halogen-free flame retardant.

8. The polypropylene composition according to any one of claims 1 to 7, characterized in that, (c) The pigment is an organic pigment and / or carbon black. When the pigment is an organic pigment, it is preferably selected from phthalocyanine green pigment and phthalocyanine blue pigment.

9. The polypropylene composition according to any one of claims 1 to 8, characterized in that, (d1) The NOR-HALS is an oxidized and hydrogenated 1,3,5-triazine-2,4,6-triamine, N2,N2'-1,6-hexadiylbis[N4,N6-dibutyl-N2,N4,N6-tris(2,2,6,6-tetramethyl-4-piperidinyl)-,N-allyl derivative (CAS: 1902936-62-2).

10. The polypropylene composition according to any one of claims 1 to 9, characterized in that, (d2) The acid scavenger is calcium stearate (CAS: 1592-23-0).

11. The polypropylene composition according to any one of claims 1 to 10, characterized in that, The polypropylene composition further comprises: (d3) 0.1 wt.-% to 0.8 wt.-% of at least one UV absorber comprising a phenolic hydroxyl group based on the total amount of the polypropylene composition, wherein the at least one UV absorber comprising a phenolic hydroxyl group is preferably selected from 2-hydroxy-4-n-octyloxybenzophenone (CAS: 1843-05-6), 2-(4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(octyloxy)-phenol (CAS: 2725-22-6) and hexadecyl-3,5-bis-tert-butyl-4-hydroxybenzoate (CAS: 67845-93-6).

12. The polypropylene composition according to any one of claims 1 to 11, characterized in that, The polypropylene composition further comprises: (d4) at least one antioxidant based on 0.1 wt.-% to 0.5 wt.-% of the total amount of the polypropylene composition and (d5) at least one metal passivator based on 0.1 wt.-% to 0.5 wt.-% of the total amount of the polypropylene composition, wherein the at least one antioxidant is preferably selected from octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS: 2082-79-3) and tris(2,4-di-tert-butylphenyl) phosphite (CAS: 31570-04-4), and (d4) the metal passivator is preferably 2,2'-oxalamido-bis-(ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS: 70331-94-1).

13. An article characterized in that, The article comprises a polypropylene composition according to any one of the preceding claims.

14. The article of claim 13, characterized in that, The article is formed as part of or constitutes a housing for: electrical equipment housings, such as battery housings; or The article is formed as part of or constitutes the cable insulation material, the container, or the power electronic component of the automobile or household appliance.

15. Use of a combination of (i) NOR-HALS and (ii) an acid scavenger, characterized in that, The combination of (i) NOR-HALS and (ii) acid scavengers is used to improve the UV stability of polypropylene compositions including nitrogen- and phosphorus-containing halogen-free flame retardants.

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