Flame retardant composition comprising high melt strength polypropylene

Abstract

The present invention relates to a flame retardant polypropylene composition (C) comprising a propylene polymer (PP), a nitrogen containing flame retardant (FR) and an anti-dripping agent (A), the anti-dripping agent (A) having a F 30 high melt strength polypropylene (HMS-PP) having a melt strength of at least 20 cN. Furthermore, the present invention also relates to a flame retardant polypropylene composition (C) having a F 30 use of a high melt strength polypropylene (HMS-PP) having a melt strength of at least 20 cN as an anti-dripping agent and an article comprising the flame retardant polypropylene composition (C).

Description

TECHNICAL FIELD

[0001] The present invention relates to a flame-retardant polypropylene composition (C) comprising a propylene polymer (PP), a nitrogen-containing flame retardant (FR) and an antidripping agent (A), the antidripping agent (A) being a high melt strength polypropylene (HMS-PP), the high melt strength polypropylene (HMS-PP) having a F 30 melt strength of at least 20 cN determined according to ISO 16790:2005. Furthermore, the present invention also relates to the use of a high melt strength polypropylene (HMS-PP) having a F 30 melt strength of at least 20 cN determined according to ISO 16790:2005 as antidripping agent and to an article comprising the flame-retardant polypropylene composition (C). BACKGROUND

[0002] In electrical applications, certain flame-retardant requirements have to be met. Most commonly, a UL94 V0 rating has to be achieved at a sample thickness equal to or less than 1.6 mm. Furthermore, for environmental friendliness, halogen-free systems are preferred.

[0003] As part of the UL94 rating, in addition to the flaming behavior controlled by the flame-retardant additives, the dripping behavior has to be controlled, where for most of the un- or low-filled polypropylene grades, polytetrafluoroethylene (PTFE) is typically used in a total amount of 0.2-0.3 wt.%. According to the regulations, flame-retardant materials combined with PTFE are still considered halogen-free, but there is still a small amount of halogen intrinsically present in practice in the formulation. Furthermore, a REACH ban has been proposed, aiming at prohibiting the manufacture, placing on the market and use of all perfluoroalkyl substances and polyfluoroalkyl substances (PFAS) in the European Union. Therefore, potential bans are being considered for fluoropolymers.

[0004] Therefore, there is a need for a replacement of PTFE in flame-retardant polypropylene formulations, where still the above flame-retardant requirements are met. In other words, it is an object of the present invention to provide a halogen-free flame-retardant polypropylene composition. SUMMARY

[0005] Therefore, the present invention relates to a flame-retardant polypropylene composition (C) comprising, based on the total weight of the flame-retardant polypropylene composition (C):

[0006] i) 23.0-80.0 wt. % of a propylene polymer (PP),

[0007] ii) 10.0-40.0 wt. % of a nitrogen-containing flame retardant (FR), and

[0008] iii) 10.0 to 37.0 wt.-% of an anti-dripping agent (A), the anti-dripping agent (A) being a high melt strength polypropylene (HMS-PP), the high melt strength polypropylene (HMS-PP) having a F 30 a melt strength of at least 20 cN, and

[0009] iv) 0.0 to 15.0 wt.-% of carbon black (CB),

[0010] wherein the flame retardant polypropylene composition (C) does not contain glass fibers.

[0011] According to an embodiment of the present application, the propylene polymer (PP) is a heterophasic propylene copolymer (HECO), the heterophasic propylene copolymer (HECO) comprising:

[0012] a) a matrix (M), the matrix (M) being a polymer of propylene, and

[0013] b) an elastomer (E), the elastomer (E) being a copolymer comprising units derived from propylene and ethylene and / or C4 to C8 a-olefins.

[0014] The present application also relates to a flame retardant polypropylene composition (C) comprising:

[0015] i) a propylene polymer (PP), the propylene polymer (PP) being a heterophasic propylene copolymer (HECO), the heterophasic propylene copolymer (HECO) comprising:

[0016] a) a matrix (M), the matrix (M) being a polymer of propylene, and

[0017] b) an elastomer (E), the elastomer (E) being a copolymer comprising units derived from propylene and ethylene and / or C4 to C8 a-olefins,

[0018] ii) a nitrogen-containing flame retardant (FR),

[0019] iii) an anti-dripping agent (A), the anti-dripping agent (A) being a high melt strength polypropylene (HMS-PP), the high melt strength polypropylene (HMS-PP) having a F 30 a melt strength of at least 20 cN, and

[0020] iv) optionally carbon black (CB).

[0021] Preferably, the flame retardant polypropylene composition (C) comprises, based on the total weight of the flame retardant polypropylene composition (C):

[0022] i) 20.0 to 65.0 wt.-% of a propylene polymer (PP),

[0023] ii) 10.0 to 40.0 wt% of a nitrogen-containing flame retardant (FR), and

[0024] iii) 10.0 to 40.0 wt% of an anti-dripping agent (A),

[0025] iv) 0.0 to 15.0 wt% of carbon black (CB).

[0026] According to one embodiment of the present invention, the flame retardant polypropylene composition (C) is halogen-free.

[0027] According to another embodiment of the present invention the total amount of propylene polymer (PP), nitrogen containing flame retardant (FR), anti-drip agent (A) and optionally carbon black (CB) together constitutes at least 90 wt%, preferably amounts to 100 wt% of the flame retardant polypropylene composition (C).

[0028] According to another embodiment of the present invention, the nitrogen-containing flame retardant (FR) comprises a first nitrogen-containing phosphate (FR1) and a second nitrogen-containing phosphate (FR2).

[0029] According to another embodiment of the present invention, the weight ratio between the first nitrogen-containing phosphate (FR1) and the second nitrogen-containing phosphate (FR2) is in the range of 60:40 to 40:60.

[0030] Particularly preferably, the first nitrogen-containing phosphate (FR1) is melamine polyphosphate, and the second nitrogen-containing phosphate (FR2) is piperazine pyrophosphate.

[0031] According to one embodiment of the present invention the heterophasic propylene copolymer (HECO) has:

[0032] i) a comonomer content of 4.0 to 17.0 mol%, preferably 6.0 to 10.0 mol%, and / or

[0033] ii) 7.0 to 25.0 wt.-%, preferably 11.0 to 22.0 wt.-%, based on the total weight of the heterophasic propylene copolymer (HECO), of a xylene cold soluble fraction (XCS).

[0034] According to another embodiment of the present invention the xylene cold soluble fraction (XCS) of the heterophasic propylene copolymer (HECO) has:

[0035] i) a comonomer content of 25.0 to 65.0 mol%, preferably 40.0 to 45.0 mol%, and / or

[0036] ii) an intrinsic viscosity (IV) of less than 3.5 dl / g, preferably 2.4 to 3.4 dl / g, measured according to ISO 1628 / 1 (135° C., decalin).

[0037] According to another embodiment of the present application, the high melt strength polypropylene (HMS-PP) has a melt flow rate MFR2(230°C, 2.16 kg) measured according to ISO 1133 in the range of 0.5 to 15.0 g / 10 min.

[0038] Especially preferred, the flame retardant polypropylene composition (C) has a melt flow rate MFR2(230°C, 2.16 kg) measured according to ISO 1133 in the range of 1.0 to 30.0 g / 10 min.

[0039] The present application also relates to the use of a high melt strength polypropylene (HMS-PP) as anti-dripping agent (A) in a composition comprising a propylene polymer (PP) and a nitrogen containing flame retardant (FR), the high melt strength polypropylene (HMS-PP) having a F 30 a melt strength of at least 20 cN, wherein

[0040] a) the composition is free of glass fibers, and / or

[0041] b) the propylene polymer (PP) is a heterophasic propylene copolymer (HECO), the heterophasic propylene copolymer (HECO) comprising:

[0042] a matrix (M), the matrix (M) being a polymer of propylene, and

[0043] an elastomer (E), the elastomer (E) being a copolymer comprising units derived from propylene and ethylene and / or C4to C8a-olefins.

[0044] The present application also relates to an article comprising the flame retardant polypropylene composition (C) as described above.

[0045] In the following, the present application is explained in more detail. DETAILED DESCRIPTION

[0046] Flame retardant polypropylene composition (C)

[0047] The flame retardant polypropylene composition (C) according to the present application comprises a propylene polymer (PP), a nitrogen containing flame retardant (FR) and an anti-dripping agent (A), the anti-dripping agent (A) being a high melt strength polypropylene (HMS-PP), the high melt strength polypropylene (HMS-PP) having a F 30 a melt strength of at least 20 cN.

[0048] According to a preferred embodiment of the present application, the flame retardant polypropylene composition (C) does not contain a fluorine-containing polymer. In particular, preferably, the flame retardant polypropylene composition (C) does not contain a fluorine-containing polymer in an amount of more than 0.5 wt%, more preferably more than 0.1 wt%, still more preferably more than 0.01 wt%, for example more than 0.001 wt%. Especially preferably, no fluorine-containing polymer is used in the manufacture of the flame retardant polypropylene composition (C).

[0049] As used herein, the term "fluorine-containing polymer" refers to a polymeric compound comprising fluorine atoms. Examples of fluorine-containing polymers are poly(tetrafluoroethylene) (PTFE), tetrafluoroethylene-hexafluoropropylene-copolymer (FEP) and polychlorotrifluoroethylene (PCTFE).

[0050] According to another preferred embodiment of the present application, the flame retardant polypropylene composition (C) does not contain halogen atoms. As used herein, the term "halogen" refers to the elements of group 17 of the periodic table. Thus, preferably, no compound containing halogen atoms is used in the manufacture of the flame retardant polypropylene composition (C).

[0051] According to an embodiment of the present application, the flame retardant polypropylene composition (C) does not contain glass fibers. In particular, preferably, the flame retardant polypropylene composition (C) does not contain glass fibers in an amount of more than 0.5 wt%, more preferably more than 0.1 wt%, still more preferably more than 0.01 wt%, for example more than 0.001 wt%. Especially preferably, no glass fibers are used in the manufacture of the flame retardant polypropylene composition (C).

[0052] According to the embodiment wherein the flame retardant polypropylene composition (C) does not contain glass fibers, the flame retardant polypropylene composition (C) comprises, based on the total weight of the flame retardant polypropylene composition (C):

[0053] i) 23.0 to 80.0 wt%, more preferably 28.0 to 65.0 wt%, still more preferably 30.0 to 55.0 wt%, for example 35.0 to 50.0 wt% of a propylene polymer (PP),

[0054] ii) 10.0 to 40.0 wt%, more preferably 12.0 to 35.0 wt%, still more preferably 18.0 to 33.0 wt%, for example 22.0 to 30.0 wt% of a nitrogen-containing flame retardant (FR), and

[0055] iii) 10.0 to 37.0 wt%, more preferably 12.0 to 36.0 wt%, still more preferably 15.0 to 32.0 wt%, for example 19.0 to 31.0 wt% of an anti-dripping agent (A).

[0056] Preferably, the total amount of propylene polymer (PP), nitrogen containing flame retardant (FR) and anti-dripping agent (A) together constitutes at least 90 wt% of the flame retardant polypropylene composition (C), more preferably the total amount is 100 wt%.

[0057] According to an embodiment of the present application, the flame retardant polypropylene composition (C) further comprises carbon black (CB). Preferably, the flame retardant polypropylene composition (C) according to said embodiment comprises, based on the total weight of the flame retardant polypropylene composition (C):

[0058] i) 23.0 to 65.0 wt%, more preferably 28.0 to 60.0 wt%, still more preferably 30.0 to 55.0 wt%, for example 35.0 to 50.0 wt% of propylene polymer (PP),

[0059] ii) 10.0 to 40.0 wt%, more preferably 12.0 to 35.0 wt%, still more preferably 18.0 to 33.0 wt%, for example 22.0 to 30.0 wt% of nitrogen containing flame retardant (FR),

[0060] iii) 10.0 to 37.0 wt%, more preferably 12.0 to 36.0 wt%, still more preferably 15.0 to 32.0 wt%, for example 19.0 to 31.0 wt% of anti-dripping agent (A), and

[0061] iv) 0.01 to 15.0 wt%, more preferably 1.0 to 12.0 wt%, still more preferably 2.0 to 11.0 wt%, for example 3.0 to 10.0 wt% of carbon black (CB).

[0062] For the embodiment wherein the flame retardant polypropylene composition (C) comprises carbon black (CB), preferably, the total amount of propylene polymer (PP), nitrogen containing flame retardant (FR), anti-dripping agent (A) and carbon black (CB) together constitutes at least 90 wt% of the flame retardant polypropylene composition (C), more preferably the total amount is 100 wt%.

[0063] The flame retardant polypropylene composition (C) according to the present application can further comprise additives (AD), for example, acid scavengers, antioxidants, colorants, light stabilizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, etc.

[0064] Therefore, preferably, the flame retardant polypropylene composition (C) comprises, more preferably consists of:

[0065] i) 23.0 to 64.99 wt%, more preferably 28.0 to 60.0 wt%, still more preferably 30.0 to 55.0 wt%, for example 35.0 to 50.0 wt% of propylene polymer (PP),

[0066] ii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 35.0 wt.-%, still more preferably 18.0 to 33.0 wt.-%, for example 22.0 to 30.0 wt.-%, of a nitrogen-containing flame retardant (FR),

[0067] iii) 10.0 to 37.0 wt.-%, more preferably 12.0 to 36.0 wt.-%, still more preferably 15.0 to 32.0 wt.-%, for example 19.0 to 31.0 wt.-%, of an anti-dripping agent (A),

[0068] iv) 0.01 to 15.0 wt.-%, more preferably 1.0 to 12.0 wt.-%, still more preferably 2.0 to 11.0 wt.-%, for example 3.0 to 10.0 wt.-%, of carbon black (CB), and

[0069] v) 0.01 to 5.0 wt.-%, more preferably 0.1 to 3.5 wt.-%, still more preferably 0.2 to 2.0 wt.-%, for example 0.3 to 1.0 wt.-%, of an additive (AD). In the following, the additive (AD) is described in more detail.

[0070] For embodiments wherein the flame-retardant polypropylene composition (C) comprises the additive (AD), preferably the total amount of the propylene polymer (PP), the nitrogen-containing flame retardant (FR), the anti-dripping agent (A), the optional carbon black (CB) and the additive (AD) together make up at least 90 wt.-%, more preferably 100 wt.-%, of the flame-retardant polypropylene composition (C).

[0071] According to another embodiment of the present application, the propylene polymer (PP) is a heterophasic propylene copolymer (HECO), the heterophasic propylene copolymer (HECO) comprising: a matrix (M), the matrix (M) being a polymer of propylene; and, an elastomer (E), the elastomer (E) being a copolymer comprising units derived from propylene and ethylene and / or C4 to C8 alpha-olefins.

[0072] For embodiments wherein the propylene polymer (PP) is a heterophasic propylene copolymer (HECO), the flame-retardant polypropylene composition (C) comprises, based on the total weight of the flame-retardant polypropylene composition (C):

[0073] i) 20.0 to 80.0 wt.-%, more preferably 28.0 to 65.0 wt.-%, still more preferably 30.0 to 55.0 wt.-%, for example 35.0 to 50.0 wt.-%, of a propylene polymer (PP), the propylene polymer (PP) being a heterophasic propylene copolymer (HECO),

[0074] ii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 35.0 wt.-%, still more preferably 18.0 to 33.0 wt.-%, for example 22.0 to 30.0 wt.-%, of a nitrogen containing flame retardant (FR), and

[0075] iii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 36.0 wt.-%, still more preferably 15.0 to 32.0 wt.-%, for example 19.0 to 31.0 wt.-%, of an anti-dripping agent (A).

[0076] Preferably, the total amount of the propylene polymer (PP) being a heterophasic propylene copolymer (HECO), the nitrogen containing flame retardant (FR) and the anti-dripping agent (A) together make up at least 90 wt.-%, more preferably 100 wt.-%, of the flame retardant polypropylene composition (C).

[0077] According to an embodiment of the present application, the flame retardant polypropylene composition (C) further comprises carbon black (CB). Preferably, the flame retardant polypropylene composition (C) according to said embodiment comprises, based on the total weight of the flame retardant polypropylene composition (C):

[0078] i) 20.0 to 65.0 wt.-%, more preferably 28.0 to 60.0 wt.-%, still more preferably 30.0 to 55.0 wt.-%, for example 35.0 to 50.0 wt.-%, of a propylene polymer (PP) being a heterophasic propylene copolymer (HECO),

[0079] ii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 35.0 wt.-%, still more preferably 18.0 to 33.0 wt.-%, for example 22.0 to 30.0 wt.-%, of a nitrogen containing flame retardant (FR),

[0080] iii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 36.0 wt.-%, still more preferably 15.0 to 32.0 wt.-%, for example 19.0 to 31.0 wt.-%, of an anti-dripping agent (A), and

[0081] iv) 0.01 to 15.0 wt.-%, more preferably 1.0 to 12.0 wt.-%, still more preferably 2.0 to 11.0 wt.-%, for example 3.0 to 10.0 wt.-%, of carbon black (CB).

[0082] For the embodiment wherein the flame retardant polypropylene composition (C) comprises carbon black (CB), preferably, the total amount of the propylene polymer (PP) being a heterophasic propylene copolymer (HECO), the nitrogen containing flame retardant (FR), the anti-dripping agent (A) and the carbon black (CB) together make up at least 90 wt.-%, more preferably 100 wt.-%, of the flame retardant polypropylene composition (C).

[0083] The flame-retardant polypropylene composition (C) according to the above embodiments of the present application can further comprise additives (AD), such as, for example, acid scavengers, antioxidants, colorants, light stabilizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, and the like.

[0084] Therefore, preferably, the flame-retardant polypropylene composition (C) comprises, more preferably consists of, based on the total weight of the flame-retardant polypropylene composition (C):

[0085] i) 20.0 to 64.99 wt.-%, more preferably 28.0 to 60.0 wt.-%, still more preferably 30.0 to 55.0 wt.-%, such as 35.0 to 50.0 wt.-%, of a propylene polymer (PP), which is a heterophasic propylene copolymer (HECO),

[0086] ii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 35.0 wt.-%, still more preferably 18.0 to 33.0 wt.-%, such as 22.0 to 30.0 wt.-%, of a nitrogen-containing flame retardant (FR),

[0087] iii) 10.0 to 40.0 wt.-%, more preferably 12.0 to 36.0 wt.-%, still more preferably 15.0 to 32.0 wt.-%, such as 19.0 to 31.0 wt.-%, of an anti-dripping agent (A),

[0088] iv) 0.01 to 15.0 wt.-%, more preferably 1.0 to 12.0 wt.-%, still more preferably 2.0 to 11.0 wt.-%, such as 3.0 to 10.0 wt.-%, of carbon black (CB), and

[0089] v) 0.01 to 5.0 wt.-%, more preferably 0.1 to 3.5 wt.-%, still more preferably 0.2 to 2.0 wt.-%, such as 0.3 to 1.0 wt.-%, of additives (AD). In the following, the additives (AD) are described in more detail.

[0090] For embodiments wherein the flame-retardant polypropylene composition (C) comprises additives (AD), preferably the total amount of the propylene polymer (PP) which is a heterophasic propylene copolymer (HECO), the nitrogen-containing flame retardant (FR), the anti-dripping agent (A), the optional carbon black (CB), and the additives (AD) together make up at least 90 wt.-%, more preferably 100 wt.-%, of the flame-retardant polypropylene composition (C).

[0091] Preferably, the flame retardant polypropylene composition (C) according to the present application has a melt flow rate MFR2(230 °C, 2.16 kg) of 1.0 to 30.0 g / 10 min, more preferably of 3.0 to 20.0 g / 10 min, still more preferably of 4.0 to 15.0 g / 10 min, for example of 5.0 to 10.0 g / 10 min, determined according to ISO 1133.

[0092] With regard to the mechanical properties, preferably the flame retardant polypropylene composition (C) has a tensile modulus of 1000 to 5000 MPa, more preferably of 1100 to 3000 MPa, still more preferably of 1500 to 2500 MPa, for example of 1700 to 2200 MPa, determined according to ISO 527-1 A at 23 °C.

[0093] Additionally or alternatively to the preceding paragraph, preferably the flame retardant polypropylene composition (C) has a Charpy notched impact strength of at least 2.0 kJ / m 2 , more preferably of 2.0 to 30.0 kJ / m 2 , still more preferably of 2.2 to 20.0 kJ / m 2 , for example of 2.5 to 10.0 kJ / m 2 , determined according to ISO 179 leA at 23 °C.

[0094] Further, preferably the flame retardant polypropylene composition (C) according to the present application fulfils the requirements of the plastic material flammability safety standard UL 94 V-0 at a thickness of equal to or less than 1.6 mm, more preferably of equal to or less than 1.2 mm, still more preferably of equal to or less than 1.0 mm, for example of equal to or less than 0.9 mm.

[0095] Preferably, the flame retardant polypropylene composition (C) is obtained by blending, preferably melt blending, the propylene polymer (PP), the nitrogen-containing flame retardant (FR), the anti-dripping agent (A) and, optionally, the carbon black (CB) and the additives (AD).

[0096] In the following, the propylene polymer (PP), the nitrogen-containing flame retardant (FR), the anti-dripping agent (A) are described in more detail.

[0097] Propylene polymer (PP)

[0098] The flame retardant polypropylene composition (C) according to the present application comprises a propylene polymer (PP). The propylene polymer (PP) can also be a mixture of two or more propylene polymer (PP) components.

[0099] The propylene polymer (PP) has a melt flow rate MFR2(230 °C, 2.16 kg) measured according to ISO 1133 in the range of 5.0 to 300 g / 10 min, more preferably in the range of 8.0 to 100 g / 10 min, still more preferably in the range of 10.0 to 75.0 g / 10 min, for example in the range of 15.0 to 50.0 g / 10 min.

[0100] The propylene polymer (PP) can be a homo- or copolymer of propylene. Furthermore, the propylene polymer (PP) can comprise more than one different propylene polymer (PP) component.

[0101] In case the propylene polymer (PP) is a copolymer of propylene, preferably the comonomer is selected from ethylene and / or a C4to C8a-olefin. Especially preferred, the comonomer is ethylene. For propylene polymers (PP) comprising more than one (e.g. two) different propylene polymer components which are copolymers of propylene, preferably all propylene polymer components contain the same comonomer, for example ethylene.

[0102] Preferably, the propylene polymer (PP) is a copolymer of propylene and ethylene and / or at least one further C4to C8a-olefin.

[0103] The comonomer content (e.g. the ethylene content) of the propylene polymer (PP) is preferably in the range of 2.0 to 25.0 mol%, more preferably in the range of 4.0 to 20.0 mol%, still more preferably in the range of 6.0 to 15.0 mol%, for example in the range of 6.2 to 12.0 mol%.

[0104] In a preferred embodiment of the present application, the propylene polymer (PP) is a heterophasic propylene copolymer (HECO) comprising:

[0105] i) a matrix (M) which is a polymer of propylene,

[0106] ii) an elastomer (E) which is a copolymer comprising units derived from propylene and ethylene and / or a C4to C8a-olefin.

[0107] Generally, in the present application, the expression "heterophasic" means 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 the inclusions contain the elastomer. According to the present application, the term "inclusion" shall preferably mean that the matrix and the inclusions form different phases within the heterophasic polypropylene, the inclusions being visible, for example, by high resolution microscopy, such as electron microscopy or scanning force microscopy.

[0108] It is to be understood that the propylene polymer (PP) which is a heterophasic propylene copolymer (HECO) preferably has a rather low total comonomer content, preferably ethylene content. Thus, preferably the comonomer content of the heterophasic propylene copolymer (HECO) is in the range of 4.0 to 17.0 mol%, preferably in the range of 5.0 to 14.0 mol%, more preferably in the range of 6.0 to 10.0 mol%.

[0109] The heterophasic propylene copolymer (HECO) is typically characterized by a xylene cold soluble (XCS) fraction and a xylene cold insoluble (XCI) fraction. For the purpose of the present application the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO) is essentially identical to the elastomer of the heterophasic propylene copolymer (HECO).

[0110] Thus, when referring to the intrinsic viscosity and the ethylene content of the elastomer of the heterophasic propylene copolymer (HECO) it refers to the intrinsic viscosity and the ethylene content of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO).

[0111] Thus, in the propylene polymer (PP) which is a heterophasic propylene copolymer (HECO) the matrix (M) content, i.e. the xylene cold insoluble (XCI) content, is preferably in the range of 75.0 to 93.0 wt%, more preferably in the range of 77.0 to 91.0 wt%, for example in the range of 78.0 to 89.0 wt%.

[0112] On the other hand, in the propylene polymer (PP) which is a heterophasic propylene copolymer (HECO) the elastomer (E), i.e. the xylene cold soluble (XCS) content, is preferably in the range of 7.0 to 25.0 wt%, more preferably in the range of 9.0 to 23.0 wt%, for example in the range of 11.0 to 22.0 wt%.

[0113] The first component of the propylene polymer (PP) which is a heterophasic propylene copolymer (HECO) is the matrix (M).

[0114] The polypropylene suitable for use as the matrix (M) 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 C4to C8a-olefin such as, for example, 1-butene, 1-hexene or 1-octene, wherein the total comonomer content is in the range of 0.05 to 10 wt%.

[0115] Furthermore and preferably, the polypropylene matrix (M) has a moderate melt flow rate. Thus, preferably in the present application, the polypropylene matrix (M) (i.e. the xylene cold insoluble (XCI) fraction) of the propylene polymer (PP) has a melt flow rate MFR2 (230 °C, 2.16 kg) of 15.0 to 120 g / 10 min, more preferably of 20.0 to 100 g / 10 min, still more preferably of 30.0 to 80.0 g / 10 min, for example of 35.0 to 50.0 g / 10 min, determined according to ISO 1133.

[0116] Furthermore, the polypropylene matrix (M) can be multimodal or bimodal with regard to the molecular weight.

[0117] The expression "multimodal" or "bimodal" used in the present application refers to the modality of the polymer, i.e.

[0118] • the form of its molecular weight distribution curve, which is a plot of the molecular weight fraction as a function of its molecular weight, and / or

[0119] • the form of its comonomer content distribution curve, which is a plot of the comonomer content as a function of the molecular weight of the polymer fraction.

[0120] However, preferably, the polypropylene matrix (M) is not multimodal or bimodal.

[0121] The second component of the propylene polymer (PP) as a heterophasic propylene copolymer (HECO) is an elastomer (E).

[0122] The elastomer (E) comprises, preferably consists of units derivable from (i) propylene and (ii) ethylene and / or at least another C4to C8a-olefin, more preferably units derivable from (i) propylene and (ii) ethylene and at least another a-olefin selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene. The elastomeric copolymer (E) can additionally contain units derived from a conjugated diene, such as butadiene, or a non-conjugated diene, however, preferably the elastomeric copolymer consists only of units derivable from (i) propylene and (ii) ethylene and / or C4to C8a-olefins. Suitable non-conjugated dienes, if used, include linear and branched acyclic dienes, for example 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 mixed isomers of dihydromyrcene and dihydrolinolefine, as well as monocyclic alicyclic dienes, for example 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. Polycyclic 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-isopropylidenenorbornene, 5-(4-cyclopentenyl)-2-norbornene; and 5-cyclohexyliden-2-norbornene. Preferred non-conjugated dienes are 5-ethylidene-2-norbornene, 1,4-hexadiene and dicyclopentadiene.

[0123] Thus, the elastomer (E) comprises at least units derivable from propylene and ethylene, and can comprise further units derivable from further a-olefins as defined in the preceding paragraph. However, particularly preferred, the elastomer (E) comprises units derivable from propylene and ethylene only, and optionally a conjugated diene (e.g. butadiene) or a non-conjugated diene (e.g. 1,4-hexadiene) as defined in the preceding paragraph. Thus, as elastomer (E), ethylene propylene non-conjugated diene monomer polymers (EPDM) and / or ethylene propylene rubbers (EPR) are particularly preferred, the latter being most preferred.

[0124] As with the matrix (M), the elastomer (E) can be unimodal or multimodal, e.g. bimodal. With regard to the definition of unimodal and multimodal (e.g. bimodal), reference is made to the definition above.

[0125] In the present application, the content of units derivable from propylene in the elastomer (E) is equal 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 20.0 to 80.0 mol-%, more preferably in the range of 35.0 to 70.0 mol-%. The comonomers present in the xylene cold soluble (XCS) fraction are those defined above for the elastomer (E). Thus, in a particular embodiment, the elastomer (E), i.e. the xylene cold soluble (XCS) fraction, comprises 25.0 to 65.0 mol-%, more preferably 30.0 to 60.0 mol-%, still more preferably 35.0 to 50.0 mol-%, for example 40.0 to 45.0 mol-%, of units derivable from at least one of the comonomers defined above for the elastomer (E). Preferably, the elastomer (E) is an ethylene propylene non-conjugated diene monomer polymer (EPDM) or an ethylene propylene rubber (EPR), the latter being particularly preferred, wherein the propylene and / or ethylene content is as defined in this paragraph. In a preferred embodiment, the comonomer of the elastomer (E) is ethylene only.

[0126] It is a further preferred requirement of the present application that the intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of the propylene polymer (PP) (the propylene polymer (PP) being a heterophasic propylene copolymer (HECO)) is rather low. Thus, preferably, the intrinsic viscosity of the xylene cold soluble (XCS) fraction of the propylene polymer (PP) (the propylene polymer (PP) being a heterophasic propylene copolymer (HECO)) is less than 3.5 dl / g, more preferably not more than 3.4 dl / g. Even more preferably, the intrinsic viscosity of the xylene cold soluble (XCS) fraction of the propylene polymer (PP) (the propylene polymer (PP) being a heterophasic propylene copolymer (HECO)) is in the range of 1.8 dl / g to less than 3.5 dl / g, more preferably in the range of 1.9 to 3.4 dl / g, for example in the range of 2.0 to 3.4 dl / g. The intrinsic viscosity is determined according to ISO 1628 in decalin at 135 °C.

[0127] Preferably, in case the propylene polymer (PP) is a heterophasic propylene copolymer (HECO) as described above, the propylene content of the propylene polymer (PP) is in the range of 85.0 to 96.0 wt-%, more preferably in the range of 88.0 to 94.0 wt-%, based on the total weight of the propylene polymer (PP), more preferably based on the amount of the matrix (M) and the elastomeric copolymer (E) together.

[0128] The propylene polymer (PP) (the propylene polymer (PP) being a heterophasic propylene copolymer (HECO)) can be produced by blending the matrix (M) and the elastomer (E). Preferably, however, the heterophasic propylene copolymer (HECO) is produced in a sequential step process using reactors arranged in series and operated under different reaction conditions. Thus, the individual fractions produced in a particular reactor can have their own molecular weight distribution and / or comonomer content distribution.

[0129] The propylene polymer (PP) (the propylene polymer (PP) being a heterophasic propylene copolymer (HECO)) according to the present application is preferably produced in a sequential polymerization process known in the art (i.e. in a multi-stage process), wherein the (semi)crystalline propylene polymer (M) is produced in at least one slurry reactor, preferably in a slurry reactor and optionally in a subsequent gas phase reactor, and subsequently the elastomer (E) is produced in at least one (i.e. one or two) gas phase reactor.

[0130] Thus, preferably, the propylene polymer (PP) (the propylene polymer (PP) being a heterophasic propylene copolymer (HECO)) is produced in a sequential polymerization process comprising the following steps:

[0131] (a) polymerizing propylene and optionally at least one of ethylene and / or a C4to C8a-olefin in a first reactor (R1) to obtain a first polypropylene fraction of the matrix (M), preferably the first polypropylene fraction being a propylene homopolymer,

[0132] (b) optionally transferring the first polypropylene fraction to a second reactor (R2),

[0133] (c) optionally polymerizing propylene and optionally at least one of ethylene and / or a C4to C8a-olefin in the second reactor (R2) and in the presence of the first polypropylene fraction, thereby obtaining a second polypropylene fraction, preferably the second polypropylene fraction being a second propylene homopolymer, the first polypropylene fraction and optionally the second polypropylene fraction forming the matrix (M), i.e. the matrix of the heterophasic propylene copolymer (HECO),

[0134] (d) transferring the matrix (M) of step (c) to a third reactor (R3),

[0135] (e) polymerizing propylene and ethylene in the third reactor (R3) and in the presence of the matrix (M) obtained in step (a) or (c), obtaining an elastomer (E) dispersed in the matrix (M), the matrix (M) and the elastomer (E) forming the propylene polymer (PP), the propylene polymer (PP) being a heterophasic propylene copolymer (HECO).

[0136] Preferably, the propylene polymer (PP) (the propylene polymer (PP) is a heterophasic propylene copolymer (HECO)) is prepared in the presence of:

[0137] (a) a Ziegler-Natta catalyst comprising a compound of a transition metal of Group 4 to 6 of IUPAC (TC), a compound of a Group 2 metal (MC) and an internal donor (ID);

[0138] (b) optionally a co-catalyst (Co), and

[0139] (c) optionally an external donor (ED).

[0140] The Ziegler-Natta catalyst can be any stereospecific Ziegler-Natta catalyst for the polymerization of propylene, which is preferably capable of catalyzing the polymerization and copolymerization of propylene and optional comonomers at pressures of 500 to 10,000 kPa, in particular 2,500 to 8,000 kPa, and at temperatures of 40 to 110 °C, in particular 60 to 110 °C.

[0141] Preferably, the Ziegler-Natta catalyst comprises a high yield Ziegler-Natta type catalyst, which includes an internal donor component that can be used at high polymerization temperatures above 80 °C. Such high yield Ziegler-Natta catalysts can comprise succinates, diethers, citraconates, phthalates, etc., or mixtures thereof as internal donor (ID). Preferably, the internal donor (ID) does not contain phthalate compounds.

[0142] According to a preferred embodiment of the present application, the propylene polymer (PP) consists of a heterophasic propylene copolymer (HECO).

[0143] In another embodiment, the propylene polymer (PP) comprises a heterophasic propylene copolymer (HECO) and one or more further homo- or copolymers of propylene (such as further heterophasic propylene copolymers). In case the propylene polymer (PP) comprises a copolymer of propylene (such as a further heterophasic propylene copolymer), preferably, the heterophasic propylene copolymer (HECO) and the copolymer of propylene contain the same comonomer, preferably ethylene.

[0144] Flame retardant composition (FR)

[0145] The polypropylene composition (C) according to the present application comprises a nitrogen-containing flame retardant (FR).

[0146] According to a preferred embodiment of the present application, the nitrogen-containing flame retardant (FR) does not contain halogens. In other words, preferably, the nitrogen-containing flame retardant (FR) 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.

[0147] Preferably, the nitrogen-containing flame retardant (FR) comprises 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.

[0148] According to a preferred embodiment of the present application, the nitrogen-containing flame retardant (FR) comprises a first nitrogen-containing phosphate salt (FR1) and a second nitrogen-containing phosphate salt (FR2), the second nitrogen-containing phosphate salt (FR2) being different from the first nitrogen-containing phosphate salt (FR1).

[0149] Preferably, the first nitrogen-containing phosphate salt (FR1) and the second nitrogen-containing phosphate salt (FR2) are organic nitrogen-containing phosphate salts. Especially preferably, the first nitrogen-containing phosphate salt (FR1) and the second nitrogen-containing phosphate salt (FR2) are phosphate salts of a heterocyclic C3-C6- (more preferably C3-C4-) alkyl or -aryl compound comprising at least one N-atom.

[0150] Preferably, the first nitrogen-containing phosphate salt (FR1) is an organic nitrogen-containing polyphosphate salt. More preferably, the first nitrogen-containing phosphate salt (FR1) is a polyphosphate salt of a heterocyclic C3-C6- (more preferably C3-C4-) aryl compound comprising at least one N-atom. Especially preferably, the first nitrogen-containing phosphate salt (FR1) is a melamine polyphosphate salt.

[0151] Preferably, the second nitrogen-containing phosphate salt (FR2) is an organic nitrogen-containing diphosphate salt. More preferably, the second nitrogen-containing phosphate salt (FR2) is a diphosphate salt of a heterocyclic C3-C6- (more preferably C3-C4-) alkyl compound comprising at least one N-atom (e.g. two N-atoms). Especially preferably, the second nitrogen-containing phosphate salt (FR2) is a piperazine pyrophosphate salt.

[0152] According to a preferred embodiment of the present application, the weight ratio between the first nitrogen-containing phosphate salt (FR1) and the second nitrogen-containing phosphate salt (FR2) is 60:40 to 40:60.

[0153] Preferably, suitable nitrogen-containing flame retardants (FR) are commercially available. A highly suitable example of a commercially available nitrogen-containing flame retardant (FR) is the flame retardant product sold under the trade name Phlamoon-1090A manufactured and supplied by SULI.

[0154] The amount of nitrogen-containing flame retardant (FR) refers herein to the amount of nitrogen-containing flame retardant (FR) as provided by its manufacturer, based on the total weight of the polypropylene composition (C). Thus, the nitrogen-containing flame retardant (FR) can contain small amounts of other components, such as additives, flame-retardant synergists and / or carrier media. It is therefore understood that such other components are included in the amount of the nitrogen-containing flame retardant (FR).

[0155] Anti-dripping agent (A)

[0156] The polypropylene composition (C) of the present application further comprises an anti-dripping agent (A).

[0157] As used herein, the term "anti-dripping agent" refers to an additive that prevents or reduces the dripping effect of a polymeric material under UL94 test conditions. During the UL94 test, it is required to observe whether a test specimen drips, and if so, whether the droplet ignites. The rating of a polymeric product in the UL94 vertical burn test depends on the burn time and the dripping phenomenon. The burn time after removal of the ignition source determines whether the polymer is V0, VI or no rating (failed). The dripping phenomenon distinguishes the V2 rating from the VI rating. If the burning material drips and ignites the cotton placed underneath the test specimen, the rating of the polymeric product will be rated as V2. It is evident that the dripping phenomenon is important for the UL94 vertical test (see Y. Wang et al., Journal of Fire Sciences, 2012, 30(6), 477-501).

[0158] According to a preferred embodiment of the present application, the anti-dripping agent (A) does not contain halogens. In other words, preferably, the anti-dripping agent (A) 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.

[0159] According to the present application, the anti-dripping agent (A) is a high melt strength polypropylene (HMS-PP) having a F 30 The melt strength is at least 20 cN.

[0160] The high melt strength polypropylene is branched, thus differing from linear polypropylenes in that the polypropylene backbone is covered with side chains, whereas non-branched polypropylenes, i.e. linear polypropylenes, are not covered with side chains. The side chains have a significant influence on the rheology of the polypropylene. Thus, linear polypropylenes and high melt strength polypropylenes can be clearly distinguished by their flow behavior under stress.

[0161] The branching can be achieved by using a specific catalyst, i.e. a specific single-site catalyst, or by chemical modification. With regard to the preparation of branched polypropylenes obtained by using a specific catalyst, reference is made to EP 1892 264. With regard to branched polypropylenes obtained by chemical modification, reference is made to EP 0 879 830 A1. In this case, the branched polypropylenes are also referred to as high melt strength polypropylenes.

[0162] The branching index g' defines the degree of branching and is related to the amount of branching of the polymer. Preferably, the high melt strength polypropylene (HMS-PP) has a branching index g' determined according to GPC of equal to or less than 0.95, more preferably of equal to or less than 0.9, still more preferably of equal to or less than 0.85, such as equal to or less than 0.8.

[0163] The high melt strength polypropylene (HMS-PP) as the main component of the polypropylene composition has a F 30 melt strength and a V 30 melt extensibility, preferably with a F 30 melt strength and a V 30 melt extensibility. F 30 melt strength and a V 30 The melt extensibility is determined according to ISO 16790:2005.

[0164] Furthermore, the high melt strength polypropylene (HMS-PP) can be further defined by the strain hardening factor (SHF). Thus, preferably, the high melt strength polypropylene (HMS-PP) has a strain hardening factor (SHF) determined at a strain rate of 3.0 s -1 1.7, more preferably of at least 1.9, still more preferably of from 1.9 to 7.0, still more preferably of from 1.9 to 6.5, at a Hencky strain of 2.5.

[0165] Furthermore, preferably, the high melt strength polypropylene (HMS-PP) has a melt flow rate MFR2(230 °C, 2.16 kg) determined according to ISO 1133 of from 0.5 to 15.0 g / 10 min, still more preferably of from 1.0 to 10.0 g / 10 min, for example of from 1.8 to 3.0 g / 10 min.

[0166] Preferably, the high melt strength polypropylene (HMS-PP) has a melting point of at least 130 °C, more preferably of at least 135 °C, most preferably of at least 140 °C. The crystallization temperature is preferably at least 120 °C.

[0167] Furthermore, the high melt strength polypropylene (HMS-PP) can be a high melt strength random propylene copolymer (R-HMS-PP) or a high melt strength propylene homopolymer (H-HMS-PP), the latter being preferred.

[0168] For the purpose of the present application, the expression "propylene homopolymer" means a polymer consisting essentially of propylene units, i.e. consisting of at least 97 mol-%, preferably at least 98 mol-%, more preferably at least 99 mol-%, most preferably at least 99.8 mol-% of propylene units. In a preferred embodiment, only propylene units are detectable in the propylene homopolymer.

[0169] In case the high melt strength polypropylene (HMS-PP) is a high melt strength random propylene copolymer (R-HMS-PP), it comprises monomers copolymerizable with propylene, such as, for example, comonomers, such as ethylene and / or C4to Cio a-olefins, such as, for example, 1-butene and / or 1-hexene. Preferably, the high melt strength random propylene copolymer (R-HMS-PP) comprises monomers copolymerizable with propylene, in particular consists of monomers copolymerizable with propylene, selected from the group consisting of ethylene, 1-butene and 1-hexene. More specifically, the high melt strength random propylene copolymer (R-HMS-PP) comprises, in addition to propylene, units derivable from ethylene and / or 1-butene. In a preferred embodiment, the high melt strength random propylene copolymer (R-HMS-PP) comprises only units derivable from ethylene and propylene. The comonomer content in the high melt strength random propylene copolymer (R-HMS-PP) is preferably greater than 0.2 mol-% to 10.0 mol-%, more preferably greater than 0.5 mol-% to 7.0 mol-%. 12 α-olefins, in particular ethylene and / or C4to Cio a-olefins, such as, for example, 1-butene and / or 1-hexene. Preferably, the high melt strength propylene homopolymer (H-HMS-PP) comprises monomers copolymerizable with propylene, in particular consists of monomers copolymerizable with propylene, selected from the group consisting of ethylene, 1-butene and 1-hexene. More specifically, the high melt strength propylene homopolymer (H-HMS-PP) comprises, in addition to propylene, units derivable from ethylene and / or 1-butene. In a preferred embodiment, the high melt strength propylene homopolymer (H-HMS-PP) comprises only units derivable from propylene. The comonomer content in the high melt strength propylene homopolymer (H-HMS-PP) is preferably greater than 0.2 mol-% to 10.0 mol-%, more preferably greater than 0.5 mol-% to 7.0 mol-%. 10 α-olefins, in particular ethylene and / or C4to Cio a-olefins, such as, for example, 1-butene and / or 1-hexene. Preferably, the high melt strength propylene homopolymer (H-HMS-PP) comprises monomers copolymerizable with propylene, in particular consists of monomers copolymerizable with propylene, selected from the group consisting of ethylene, 1-butene and 1-hexene. More specifically, the high melt strength propylene homopolymer (H-HMS-PP) comprises, in addition to propylene, units derivable from ethylene and / or 1-butene. In a preferred embodiment, the high melt strength propylene homopolymer (H-HMS-PP) comprises only units derivable from propylene. The comonomer content in the high melt strength propylene homopolymer (H-HMS-PP) is preferably greater than 0.2 mol-% to 10.0 mol-%, more preferably greater than 0.5 mol-% to 7.0 mol-%.

[0170] In this respect, it is to be mentioned that the high melt strength polypropylene (HMS-PP), which is either a high melt strength propylene homopolymer (H-HMS-PP) or a high melt strength random propylene copolymer (R-HMS-PP), can additionally comprise unsaturated monomers, which are different from the comonomers defined for the high melt strength random propylene copolymer (R-HMS-PP). In other words, the high melt strength propylene homopolymer (H-HMS-PP) or the high melt strength random propylene copolymer (R-HMS-PP) can comprise unsaturated monomers, such as, for example, bifunctional unsaturated monomers and / or multifunctional unsaturated low molecular weight polymers, as detailed below, which are different from propylene, ethylene and other C4to Cio a-olefins. 12α-olefin. Thus, in the case of high melt strength polypropylene (HMS-PP), the definition of homo- and copolymer actually refers to unmodified polypropylene which is used to obtain high melt strength polypropylene (HMS-PP) by chemical modification (as described below).

[0171] As mentioned above, high melt strength polypropylene (HMS-PP) is a modified polypropylene. Thus, high melt strength polypropylene (HMS-PP) can be further defined by the way it is obtained. High melt strength polypropylene (HMS-PP) is preferably the result of treating unmodified polypropylene with a thermal decomposition free radical former and / or with ionizing radiation. However, in such a case, there is a high risk of degradation of the unmodified polypropylene, which is disadvantageous. Thus, preferably, the modification is achieved by using a difunctional unsaturated monomer and / or a multifunctional unsaturated low molecular weight polymer as a chemically bonded bridging unit. Suitable methods for obtaining high melt strength polypropylene (HMS-PP) are disclosed, for example, in EP 0 787 750, EP 0 879 830 A1 and EP 0 890 612 A2. All documents are incorporated herein by reference. Thus, the amount of peroxide, based on the unmodified polypropylene, is preferably in the range of 0.05 to 3.00 wt.-%.

[0172] Thus, in a preferred embodiment, high melt strength polypropylene (HMS-PP) comprises:

[0173] (a) If high melt strength polypropylene (HMS-PP) is high melt strength propylene homo- polymer (H-HMS-PP), high melt strength polypropylene (HMS-PP) comprises units derived from:

[0174] (i) propylene, and

[0175] (ii) a difunctional unsaturated monomer and / or a multifunctional unsaturated low molecular weight polymer,

[0176] or,

[0177] (b) If high melt strength polypropylene (HMS-PP) is high melt strength random propylene copolymer (R-HMS-PP), high melt strength polypropylene (HMS-PP) comprises units derived from:

[0178] (i) propylene,

[0179] (ii) ethylene and / or C4to C 10 α-olefin, for example, 1-butene and / or 1-hexene, preferably ethylene, and

[0180] (iii) a difunctional unsaturated monomer and / or a multifunctional unsaturated low molecular weight polymer.

[0181] "Di- or polyfunctional unsaturated" as used above means that there are preferably two or more non-aromatic double bonds present in, for example, divinylbenzene or cyclopentadiene or polybutadiene. Only using such di- or polyfunctional unsaturated compounds, which can be polymerized, preferably by means of free radical polymerization. The unsaturation sites in the di- or polyfunctional unsaturated compounds are not "unsaturated" in their chemical bound state, as the double bonds are each bound covalently to the polymer chain of the unmodified polypropylene.

[0182] The reaction of di- or polyfunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers (preferably having a number average molecular weight (M n ) < 10 000 g / mol) synthesized from one and / or more unsaturated monomers with unmodified polypropylene can be carried out in the presence of thermal free radical forming agents (e.g. decomposing free radical forming agents, such as thermally decomposable peroxides) and / or ionizing radiation or microwave radiation.

[0183] The di- or polyfunctional unsaturated monomers can be:

[0184] - divinyl compounds, such as divinyl aniline, m-divinylbenzene, p-divinylbenzene, divinylpentane and divinylpropane;

[0185] - allyl compounds, such as allyl acrylate, allyl methacrylate, allyl methallyl and allyl vinyl ether;

[0186] - dienes, such as 1,3-butadiene, chlorobutadiene, cyclohexadiene, cyclopentadiene, 2,3-dimethylbutadiene, heptadiene, hexadiene, isoprene and 1,4-pentadiene;

[0187] - aromatic and / or aliphatic bis(maleimide) bis(citraconimide) and mixtures of these unsaturated monomers.

[0188] Particularly preferred di- or polyfunctional unsaturated monomers are 1,3-butadiene, isoprene, dimethylbutadiene and divinylbenzene.

[0189] The polyfunctional unsaturated low molecular weight polymers (preferably having a number average molecular weight (M n ) < 10 000 g / mol) can be synthesized from one or more unsaturated monomers.

[0190] Examples of such low molecular weight polymers are:

[0191] - polybutadienes, in particular polybutadienes with different microstructures in the polymer chain (i.e. 1,4-cis, 1,4-trans and 1,2-(vinyl)) predominantly in 1,2-(vinyl) configuration,

[0192] - a copolymer of butadiene and styrene, which has 1,2-(vinyl) groups in the polymer chain.

[0193] The preferred low molecular weight polymer is polybutadiene, in particular polybutadiene having more than 50.0 wt% of butadiene in the 1,2-(vinyl) configuration.

[0194] The high melt strength polypropylene (HMS-PP) can comprise more than one difunctional unsaturated monomer and / or multifunctional unsaturated low molecular weight polymer. Even more preferably, the total of difunctional unsaturated monomer and multifunctional unsaturated low molecular weight polymer in the high melt strength polypropylene (HMS-PP) is 0.01 to 10.0 wt%, based on the high melt strength polypropylene (HMS-PP).

[0195] As mentioned above, preferably, the difunctional unsaturated monomer and / or the multifunctional unsaturated low molecular weight polymer are used in the presence of a thermal decomposition radical former.

[0196] Peroxides are preferred thermal decomposition radical formers. More preferably, the thermal decomposition radical former is selected from the group consisting of acyl peroxides, alkyl peroxides, hydroperoxides, peroxy acid esters and peroxycarbonates.

[0197] Particularly preferred are the following peroxides:

[0198] Acyl peroxides: benzoyl peroxide, 4-chlorobenzoyl peroxide, 3-methoxybenzoyl peroxide and / or methylbenzoyl peroxide.

[0199] Alkyl peroxides: allyl tert-butyl peroxide, 2,2-bis(tert-butylperoxybutane), 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl 4,4-bis(tert-butylperoxy)valerate, diisopropylaminomethyl tert-amyl peroxide, dimethylaminomethyl tert-amyl peroxide, diethylaminomethyl tert-butyl peroxide, dimethylaminomethyl tert-butyl peroxide, 1,1-di-(tert-amylperoxy)cyclohexane, tert-amyl peroxide, tert-butyl cumyl peroxide, tert-butyl peroxide and / or 1-hydroxybutyl n-butyl peroxide.

[0200] Peroxy acid esters and peroxycarbonates: butyl peracetate, cumyl peracetate, cumyl perpropionate, cyclohexyl peracetate, di-t-butyl peroxyl adipate, di-t-butyl peroxyl suberate, di-t-butyl peroxyl glutarate, di-t-butyl peroxyl phthalate, di-t-butyl peroxyl sebacate, 4-nitro cumyl perpropionate, 1-phenylethyl perbenzoate, phenylethyl nitro perbenzoate, t-butyl bicyclo(2,2,1)heptane percarboxylate, t-butyl-4-methyl perbutyrate, t-butyl cyclobutane percarboxylate, t-butyl cyclohexyl percarboxylate, t-butyl cyclopentyl percarboxylate, t-butyl cyclopropane percarboxylate, t-butyl dimethyl percinnamate, t-butyl-2-(2,2-diphenylvinyl)perbenzoate, t-butyl-4-methoxy perbenzoate, t-butyl perbenzoate, t-butyl carboxyl cyclohexane, t-butyl pernaphthoate, t-butyl peroxyl isopropyl carbonate, t-butyl per-toluic acid ester, t-butyl-1-phenylcyclopropyl percarboxylate, t-butyl-2-propyl perpentene-2-oate, t-butyl-1-methylcyclopropyl percarboxylate, t-butyl-4-nitrophenyl peracetate, t-butyl nitrophenyl peroxy carbamic acid ester, t-butyl-N-succinimidyl percarboxylate, t-butyl percrotonate, t-butyl permaleate, t-butyl permethacrylate, t-butyl peroctoate, t-butyl peroxyl isopropyl carbonate, t-butyl peroxyisobutyrate, t-butyl perpropenoate and / or t-butyl perpropionate.

[0201] Furthermore, mixtures of the above listed radical formers are also contemplated.

[0202] Preferably, the unmodified polypropylene is a propylene homopolymer.

[0203] After preparation, the high melt strength polypropylene (HMS-PP) can be subjected to a modification step to further modify the polymer. Such modification steps include, for example, grafting, wherein one or more functional comonomers are grafted to the polypropylene chain, and mastication, wherein the molecular weight of the polypropylene is reduced by combining the polymer in the molten state in an extruder with a radical generator, such as a peroxide. Such steps are well known to the person skilled in the art and references to them can be found in the literature.

[0204] additives (AD)

[0205] In addition to the propylene copolymer (PP), the nitrogen-containing flame retardant (FR) and the anti-dripping agent (A), the polypropylene composition (C) of the present application can comprise additives (AD). Typical additives are acid scavengers, antioxidants, colorants, light stabilizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, etc.

[0206] The content of the additives in the polypropylene composition (C) according to the present application is typically not more than 5.0 wt.-%, preferably in the range of 0.01 to 5.0 wt.-%, more preferably in the range of 0.1 to 3.5 wt.-%, still more preferably in the range of 0.2 to 2.0 wt.-%, for example in the range of 0.3 to 1.0 wt.-%.

[0207] Such additives are commercially available and described, for example, in "Plastic Additives Handbook", 6thEdition, 2009, by Hans Zweifel, pages 1141 to 1190.

[0208] Furthermore, the term "additive (AD)" according to the present application also includes carrier materials, in particular polymeric carrier materials.

[0209] Polymeric carrier materials

[0210] Preferably, the flame-retardant polypropylene composition (C) according to the present application does not comprise other polymers (other polymers being different from the propylene polymer (PP) and the high melt strength polypropylene (HMS-PP)) in an amount of more than 5.0 wt.-%, preferably in an amount of more than 3.0 wt.-%, more preferably in an amount of more than 2.0 wt.-%, based on the weight of the flame-retardant polypropylene composition (C). Any polymer which is a carrier material for an additive (AD) is not included in the amount of the polymeric compounds indicated in the present application, but is included in the amount of the respective additive.

[0211] The polymeric carrier material of the additive (AD) is a carrier polymer which ensures a homogeneous distribution in the flame-retardant polypropylene composition (C) according to the present application. The polymeric carrier material is not limited to a specific polymer. The polymeric carrier material can be an ethylene homopolymer, an ethylene copolymer obtained from ethylene and an alpha-olefin comonomer, for example a C3 to C8 alpha-olefin comonomer, a propylene homopolymer and / or a propylene copolymer obtained from propylene and an alpha-olefin comonomer, for example ethylene and / or a C4 to C8 alpha-olefin comonomer. Preferably, the polymeric carrier material does not contain monomeric units derived from styrene or derivatives thereof.

[0212] Use

[0213] The present application also relates to the use of a high melt strength polypropylene (HMS-PP) as anti-dripping agent (A) in a composition comprising a propylene polymer (PP) and a nitrogen-containing flame retardant (FR), the high melt strength polypropylene (HMS-PP) having a F 30Melt strength of at least 20 cN, wherein the composition is free of glass fibers and / or the propylene polymer (PP) is a heterophasic propylene copolymer (HECO) comprising a matrix (M) which is a polymer of propylene and an elastomer (E) which is a copolymer comprising units derived from propylene and ethylene and / or C4to C8a-olefins.

[0214] With regard to the propylene polymer (PP), the heterophasic propylene copolymer (HECO), the high melt strength polypropylene (HMS-PP) and the nitrogen containing flame retardant (FR), reference is made to the definitions provided above.

[0215] Article

[0216] The present application also relates to an article comprising the flame retardant polypropylene composition (C) as described above. The present application in particular relates to an article comprising at least 60 wt%, more preferably at least 80 wt%, still more preferably at least 90 wt%, such as at least 95 wt% or at least 99 wt% of the flame retardant polypropylene composition (C) as described above. In an especially preferred embodiment, the present application relates to an article consisting of the flame retardant polypropylene composition (C) as described above.

[0217] Preferably, the article is an automotive article in the field of electronic components, such as cable insulation materials, housings for electrical equipment, containers and parts for power electronic components of automotive parts and home appliance parts, and the like.

[0218] The present application will now be described in more detail by means of the following examples provided hereinafter.

[0219] Example

[0220] A. Measurement methods

[0221] The following definitions of terms and determination methods apply to the above general description of the application as well as to the below examples unless otherwise defined.

[0222] MFR2(230 °C) was determined according to ISO 1133 (230 °C, 2.16 kg load).

[0223] Quantification of the microstructure by NMR spectroscopy

[0224] Quantification of the comonomer content and comonomer sequence distribution of the polymers was performed by quantitative nuclear magnetic resonance (NMR) spectroscopy. For 1 H and 13 C, quantitative 13 C{ 1H}NMR spectroscopy. The use of 13 All spectra were recorded at 125 °C using a 10 mm extended temperature probehead optimized for C, and all pneumatics used nitrogen. Approximately 200 mg of material was dissolved in 3 ml of 1,2-tetrachloroethane-d2(TCE-d2) with chromium(III) acetylacetonate (Cr(acac)3) to give a 65 mM solution of relaxant in solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogeneous solution, the NMR tube was further heated in a rotating oven for at least 1 hour after initial sample preparation in the heating block. After insertion into the magnet the tube was spun at 10 Hz. This setting was chosen primarily for high resolution and as required for accurate ethylene content quantification. Standard single pulse excitation with NOE suppression was employed using an optimised tip angle, recycle delay of 1 s and a two-step WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128). A total of 6144 (6k) transients were acquired for each spectrum.

[0225] Quantitative 13 C{ 1 H}NMR spectra were processed, integrated and the relevant quantitative properties determined from the integrals. All chemical shifts were internally referenced to the centre methylene of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach was similarly referenced even in the absence of this structural unit. Characteristic signals corresponding to the incorporation of ethylene were observed (Cheng, H. N., Macromolecules 17 (1984), 1950).

[0226] For polypropylene homopolymers, all chemical shifts were internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm.

[0227] Characteristic signals corresponding to regio defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, H. N., Macromolecules 17 (1984), 1950) or comonomer were observed.

[0228] The stereoregularity distribution was quantified by integrating the methyl region between 23.6 and 19.7 ppm, correcting for any sites not related to the target stereosequence (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, A. L., Macromoleucles 30 (1997) 6251).

[0229] In particular, the influence of regio defects and comonomer on the quantification of the stereoregularity distribution was corrected by subtracting representative regio defects and comonomer integrals from the specific integral region of the stereosequence.

[0230] The isotacticity was determined at pentad level and reported as the percentage of isotactic pentad (mmmm) sequences with respect to all pentad sequences:

[0231] [mmmm] % = 100 x (mmmm / sum of all pentads).

[0232] The presence of 2,1-erythro regio defects was indicated by the presence of two methyl sites at 17.7 and 17.2 ppm and confirmed by other characteristic sites.

[0233] Characteristic signals corresponding to other types of regio defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253) were not observed.

[0234] The amount of 2,1-erythro regio defects was quantified using the average integral of the two characteristic methyl sites at 17.7 and 17.2 ppm:

[0235] P 21e = (I e6 + I e8 ) / 2

[0236] 1,2 primary inserted propylene is quantified based on the methyl region and corrected for sites included in this region that are not primary inserted and primary inserted sites not included in this region:

[0237] P 12 = I CH3 + P 12e

[0238] The total amount of propylene is quantified as the sum of primary inserted propylene and all other region defects present:

[0239] P 总 = P 12 + P 21e

[0240] The molar percentage of 2,1 erythro region defects is quantified relative to all propylene:

[0241] [21 e] mol% = 100 x (P 21e / P 总 ).

[0242] For the copolymer, the characteristic signal corresponding to ethylene incorporation was observed (Cheng, H. N., Macromolecules 17 (1984), 1950).

[0243] In case region defects are also observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, H. N., Macromolecules 17 (1984), 1950), the influence of these defects on the comonomer content needs to be corrected.

[0244] The comonomer fraction is quantified using the method of Wang et al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) by integration of multiple signals over the entire spectral region in the 13C{ 1 H} spectrum. This method was chosen because of its robust nature and the ability to determine the presence of region defects when needed. The integration region was slightly adjusted to improve applicability over the entire range of comonomer contents encountered.

[0245] For systems where only isolated ethylene in the PPEPP sequence is observed, the method of Wang et al. was modified to reduce the influence of non-zero integrals for sites known to be absent. This method reduces the overestimation of ethylene content in such systems and is achieved by reducing the number of sites used to determine the absolute ethylene content to:

[0246] E = 0.5 (Sββ + Sβγ + Sβδ + 0.5 (Sαβ + Sαγ))

[0247] By using this set of sites, the corresponding integral equation becomes:

[0248] E = 0.5 (I H + I G + 0.5 (I C + I D )

[0249] The same notation as used in the article of Wang et al. was used (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157). The equation for the absolute propylene content was not modified.

[0250] The mole fraction of comonomer incorporation was calculated from the mole fraction:

[0251] E [mol%] = 100 x fE

[0252] The weight fraction of comonomer incorporation was calculated from the mole fraction:

[0253] E [wt%] = 100 x (fE x 28.06) / ((fE x 28.06) + ((1 - fE) x 42.08))

[0254] The analysis method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150) was used to determine the comonomer sequence distribution at the triad level. This method was chosen for its robust nature, with the integration region slightly adjusted to increase applicability to a broader comonomer content range.

[0255] Intrinsic viscosity (IV): The intrinsic viscosity (IV) of propylene homopolymers and copolymers was determined according to DIN ISO 1628 / 1, October 1999 (in decalin at 135 °C).

[0256] Xylene cold soluble (XCS, wt%): The content of xylene cold soluble (XCS) was determined according to ISO 16152; 1stEdition; 2005-07-01 at 25 °C.

[0257] Charpy notched impact strength was determined according to ISO 179-1 / 1 eA at 23 °C and -30 °C by using injection moulded test specimens (80 x 10 x 4 mm) prepared according to EN ISO 1873-2.

[0258] Tensile properties were determined on 4 mm thick injection moulded dog-bone specimens prepared according to EN ISO 1873-2. Tensile modulus was determined according to ISO 527-1A at a strain rate of 1 mm / min and at 23 °C, 80 °C and 120 °C, the yield stress was determined at a strain rate of 50 mm / min and at 23 °C, 80 °C and 120 °C.

[0259] Branching coefficient g'

[0260] The relative amount of branching was determined using the g' coefficient of the branched polymer sample. The long chain branching (LCB) index is defined as g' = [η] br / [η] lin . It is well known that if the g' value increases, the content of branches decreases. [η] is the intrinsic viscosity of the polymer sample at a certain molecular weight in TCB at 160 °C and was measured by an online viscosity and concentration detector. The intrinsic viscosity was measured using the Solomon-Gatesman equation as described in the manual of Cirrus Multi-Offline SEC software version 3.2.

[0261] The necessary concentration of each elution slice was determined by the RI detector.

[0262] [η] lin is the intrinsic viscosity of the linear sample, [η] br is the viscosity of the branched sample of the same molecular weight and chemical composition. The number average g' n and the weight average g' w are defined as:

[0263]

[0264] where a i is the dW / dlogM of fraction i, and A i is the cumulative dW / dlogM of the polymer up to fraction i. The [η] lin of the linear reference (linear isotactic PP) was measured using an online viscosity detector with respect to the molecular weight. In the molecular weight range of logM = 4.5-6.1, the following K and a values were obtained from the linear reference (K = 30.68 x 10 -3 , a = 0.681). The [η] lin , i = K x M i α[η] for each slice molecular weight for g' calculation lin [η] was measured for each particular sample by an online viscosity and concentration detector br ,i.

[0265] gpcbr index :

[0266] The gpcBR index was calculated by using the following equation:

[0267]

[0268] wherein Mw(LS15) was calculated from the 15° light scattering elution area and [η] (bulk) was calculated from the corresponding viscosity detector elution area by using Cirrus Multi-Offline SEC software, version 3.2, and the following methods.

[0269]

[0270]

[0271] wherein K LS is the 15° light scattering constant, dn / dc is the refractive index increment calculated from the detector constant of the RI detector, K IV is the detector constant of the viscometer, Sp i is the specific viscosity at each chromatographic slice, and C is the corresponding concentration in g / dl.

[0272] F 30 Melt strength and v 30 Melt elongation

[0273] The tests described herein were performed according to ISO 16790:2005. The strain hardening behavior was determined by the method described in the article "Rheotens-Mastercurves and Drawability of Polymer Melts", M.H. Wagner, Polymer Engineering and Science, Vol. 36, pp. 925-935. The strain hardening behavior of the polymers was analyzed by a Rheotens apparatus (product of Gottfert, Siemensstr. 2, 74711 Buchen, Germany), in which a melt strand was drawn downward at a defined acceleration and elongated.

[0274] ​The Rheotens test simulates the industrial spinning and extrusion process. In principle, the melt is pressed or extruded through a circular die and the resulting strand is drawn off. The stress on the extrudate is recorded as a function of the melt properties and the measured parameters, in particular the ratio between output and haul-off speed, which is in fact a measure for the extension rate. For the results below, the material was extruded with a laboratory extruder HAAKE Polylab system and a gear pump with a cylindrical die (L / D = 6.0 / 2.0 mm). To measure the F 30 Melt strength and v 30 Melt extensibility by by-passing a part of the extruded polymer, the pressure at the extruder outlet (= gear pump inlet) was set to 30 bar.

[0275] The gear pump was pre-adjusted to a strand extrusion rate of 5 mm / s and the melt temperature was set to 200 °C. The spinning length between the die and the Rheotens wheel was 80 mm. At the beginning of the test, the take-up speed of the Rheotens wheel was adjusted to the speed of the extruded polymer strand (zero stretching force); then the experiment was started by slowly increasing the take-up speed of the Rheotens until the polymer filament broke. The acceleration of the wheel was small enough to measure the pulling force under quasi-steady conditions. The acceleration of the melt strand drawn down was 120 mm / s 2 The Rheotens was operated in combination with the computer (PC) program EXTENS. This is a real-time data acquisition program which displays and stores the measured data of the pulling force and the draw-down speed. The end point of the Rheotens curve (force versus pulley rotation speed) at the breaking of the polymer strand was taken as the F 30 Melt strength and v 30 Melt extensibility value.

[0276] UL 94 Vertical Burning Test was performed according to UL 94:2016. The samples were injection molded into plaques of 125 ± 5 mm length, 13.0 ± 0.5 mm width, 0.025 ~ 13 mm thickness. Under preconditioning condition I, the samples must be conditioned for 48 hours at a constant room temperature of 23 ± 2 °C and humidity of 50 ± 10 %. Under preconditioning condition II, the samples must be conditioned for 168 hours at 70 ± 1 °C in an air-circulating oven, then cooled in a desiccator at room temperature for at least 4 hours before testing. The test must be performed within 30 min after the sample is removed from conditioning. The sample is suspended vertically in the test chamber, and a first ignition is performed for 10 seconds, followed by a second ignition for 10 seconds. The burning time after each ignition is recorded, and attention is paid to whether there is afterglow, whether there are burning drips of cotton at the bottom of the ignition chamber, and whether there is flame or burning to the fixture clamp. The classification is V-0, V-1, V-2, or no classification, depending on the thickness of the test object.

[0277] Dripping Test

[0278] This method is intended to determine how different formulation droplets are when burned. A metal grid with a size of 8 mesh and a diameter of 150 mm is used. The test panels of each polymer composition are pressed to 3.0 mm thickness and cut to an area of 65 x 65 mm. Before testing, the samples are conditioned at 23 °C at 50 % relative humidity for at least 16 hours. The test is then performed in a fume hood. The temperature inside the fume hood should be (23 ± 10) °C. The flow meter is calibrated when the gas cylinder is changed. The recorder is calibrated and the flow on the flow meter is set to butane: 650 ± 30 ml / min (23 °C, 100 kPa). The panel is placed in the middle of the grid. The burner is lit, the flame is stabilized to about 130 mm, and the inner blue flame is about 50 mm. The burner is placed at a 45 degree angle to the center of the sample, and the front end of the inner blue flame touches the center of the surface of the test object. The burner is held in this position throughout the test execution. Depending on the flammability of the material, the test time varies greatly. When the sample stops burning, the burner is removed. At least three tests are performed for each sample. The droplets are collected in a bottom water bath. The water is dried, and the droplets are weighed. The weight of the remaining dried droplets is divided by the original mass (m / m) and calculated as a wt% of the original mass. This test is a comparable test and comparable materials can be divided.

[0279] 2. Examples

[0280] Propylene polymer (PP)

[0281] Catalyst preparation

[0282] The catalyst for the preparation of PP was prepared as follows:

[0283] Into a 20 L reactor 3.4 L of 2-ethylhexanol and 810 mL of propylene glycol butyl monoether (molar ratio 4 / 1) were added. Then, 7.8 L of BEM (butyl ethyl magnesium) 20% solution in toluene supplied by Crompton GmbH were slowly added to the well stirred mixture of alcohols. During the addition the temperature was kept at 10 °C. After the addition the temperature of the reaction mixture was increased to 60 °C and the mixing was continued at this temperature for 30 min. Finally, after cooling to room temperature the obtained Mg-alkoxide was transferred to a storage container. 21.2 g of the above prepared Mg-alkoxide were mixed with 4.0 mL of bis(2-ethylhexyl) citraconate for 5 min. After the mixing the obtained Mg-complex was immediately used for the preparation of the catalyst component. At 25 °C 19.5 mL of titanium tetrachloride were placed in a 300 mL reactor equipped with a mechanical stirrer. The mixing speed was adjusted to 170 rpm. The temperature was kept at 25 °C and 26.0 g of the above prepared Mg-complex were added within 30 minutes. 3.0 mL of Viscoplex 1-254 and 1.0 mL of a toluene solution containing 2 mg of Necadd 447 were added. Then, 24.0 mL of heptane were added to form an emulsion. The mixing was continued at 25 °C for 30 minutes. Then, the temperature of the reactor was increased to 90 °C within 30 minutes. The reaction mixture was stirred at 90 °C for further 30 minutes. After that the stirring was stopped and the reaction mixture was allowed to stand at 90 °C for 15 minutes.

[0284] The solid material was washed 5 times: washing was performed at 80 °C with 170 rpm stirring for 30 min. After stopping the stirring the reaction mixture was allowed to stand for 20-30 minutes followed by siphoning.

[0285] Washing 1 : washing was performed with a mixture of 100 mL of toluene and 1 mL of the donor.

[0286] Washing 2: washing was performed with a mixture of 30 mL of TiCl4and 1 mL of the donor.

[0287] Washing 3: washing was performed with 100 mL of toluene.

[0288] Washing 4: washing was performed with 60 mL of heptane.

[0289] Washing 5: washing was performed with 60 mL of heptane with 10 minutes stirring.

[0290] After that the stirring was stopped and the reaction mixture was allowed to stand for 10 minutes, the temperature was decreased to 70 °C followed by siphoning and after that bubbling with N2for 20 minutes to produce the air sensitive powder.

[0291] VCH modification of the catalyst

[0292] Into a 125 mL stainless steel reactor, at room temperature, under inert conditions, 35 mL of mineral oil (Paraffinum Liquidum PL68) were added, followed by 0.82 g of triethylaluminium (TEAL) and 0.33 g of dicyclopentyl dimethoxysilane (donor D). After 10 min, 5.0 g of the catalyst prepared in 1a (Ti content 1.4 wt%) were added, and after further 20 min, 5.0 g of vinylcyclohexane (VCH) were added. The temperature was raised to 60 °C within 30 min and maintained at this temperature for 20 h. Finally, the temperature was decreased to 20 °C and the concentration of unreacted VCH in the oil / catalyst mixture was analyzed, which was found to be 120 ppm by weight.

[0293] The process for the preparation of the propylene polymers (PP), which are heterophasic propylene copolymers, is summarized in Table 1.

[0294] Table 1: Preparation of propylene polymers (PP)

[0295]

[0296]

[0297] Preparation of the polypropylene composition (C)

[0298] The propylene polymers PP were melt blended with the flame retardant composition (FR) and the anti-dripping agent (A) in the amounts shown in Table 2 below on a co-rotating twin-screw extruder.

[0299] Table 2: Composition and properties of comparative and inventive examples

[0300] CE1 IE1 IE2 PP [wt%] 66.7 37.0 47.0 FR [wt%] 25.0 25.0 25.0 hms-pp [wt%] 30.0 20.0 ptfe [wt%] 0.3 cb (40%) [wt%] 8.0 8.0 8.0 mfr [g / 10 min] 8.1 6.3 8.3 nis [kJ / m 2 ]]]> 3.1 2.8 2.6 ul 94 (1.6 mm) [-] V0 1 ]]> V0 1 ]]> V0 1 ]]> tm [mpa] 1820 2040 1830

[0301] 1 After pre-treatment condition I of the UL 94 test

[0302] FR is the commercial flame retardant composition SULI Phlamoon-1090A of Clariant comprising 55-60 wt% melamine polyphosphate and 40-55 wt% piperazine pyrophosphate.

[0303] HMS-PP is the commercial long-chain branched polypropylene WB140HMS of Borealis having a melt flow rate MFR2 (230 °C, 2.16 kg) of 2.1 g / 10 min, a F 30 The melt strength is 36 cN, V30 The melt elongation is 230 mm / sec.

[0304] PTFE is the commercial PTFE DYNEON TF 2025Z PTFE (3M).

[0305] CB is a commercially available carbon black masterbatch CBMB-LD-09-A02 (40% carbon black in PE)

[0306] As can be seen from Table 2, the inventive compositions comprising HMS-PP (instead of PTFE) as anti-dripping agent rate V0, with the occurrence of dripping phenomena at a low level.

Claims

1. A flame retardant polypropylene composition C, based on the total weight of the flame retardant polypropylene composition C, comprising: i) 23.0 to 80.0 wt% of propylene polymer PP, wherein: The propylene polymer PP is a heterophasic propylene copolymer HECO comprising: a) a matrix M, said matrix M being a polymer of propylene, and b) an elastomer E, said elastomer E being a copolymer comprising units derived from propylene and ethylene and / or C4-C8 α-olefins, ii) 10.0 to 40.0 wt% of a nitrogen-containing flame retardant FR, and iii) 10.0 to 37.0 wt% of an anti-drip agent A, wherein the anti-drip agent A is a high melt strength polypropylene HMS-PP, and the high melt strength polypropylene HMS-PP has an F value determined according to ISO 16790:2005. 30 a melt strength of at least 20 cN, and iv) 0.0 to 15.0 wt% of carbon black CB, Wherein, the flame retardant polypropylene composition C does not contain glass fiber, The total amount of the propylene polymer PP, the nitrogen-containing flame retardant FR, the anti-dripping agent A and the optional carbon black CB accounts for 100 wt% of the flame retardant polypropylene composition C.

2. Flame retardant polypropylene composition C, comprising: i) a propylene polymer PP, wherein the propylene polymer PP is a heterophasic propylene copolymer HECO, and the heterophasic propylene copolymer HECO comprises: a) a matrix M, said matrix M being a polymer of propylene, and b) an elastomer E, said elastomer E being a copolymer comprising units derived from propylene and ethylene and / or C4-C8 α-olefins, ii) nitrogen-containing flame retardant FR, iii) an anti-drip agent A, wherein the anti-drip agent A is a high melt strength polypropylene HMS-PP, and the high melt strength polypropylene HMS-PP has an F value determined according to ISO 16790:2005. 30 a melt strength of at least 20 cN, and iv) optionally carbon black CB, in, The total amount of the propylene polymer PP, the nitrogen-containing flame retardant FR, the anti-dripping agent A and the optional carbon black CB accounts for 100 wt% of the flame retardant polypropylene composition C.

3. The flame retardant polypropylene composition C according to claim 2, wherein Based on the total weight of the flame retardant polypropylene composition C, the flame retardant polypropylene composition C comprises: i) 20.0 to 65.0 wt% of propylene polymer PP, ii) 10.0 to 40.0 wt% of a nitrogen-containing flame retardant FR, iii) 10.0 to 40.0 wt% of an anti-dripping agent A, and iv) 0.0 to 15.0 wt% of carbon black CB.

4. The flame retardant polypropylene composition C according to claim 1 or 2, wherein The flame retardant polypropylene composition C does not contain halogen.

5. The flame retardant polypropylene composition C according to claim 1 or 2, wherein: The nitrogen-containing flame retardant FR includes a first nitrogen-containing phosphate FR1 and a second nitrogen-containing phosphate FR2.

6. The flame retardant polypropylene composition C according to claim 5, wherein The weight ratio between the first nitrogen-containing phosphate FR1 and the second nitrogen-containing phosphate FR2 is 60:40 to 40:

60.

7. The flame retardant polypropylene composition C according to claim 6, wherein The first nitrogen-containing phosphate FR1 is melamine polyphosphate, and the second nitrogen-containing phosphate FR2 is piperazine pyrophosphate.

8. The flame retardant polypropylene composition C according to claim 1 or 2, wherein: The heterophasic propylene copolymer HECO has: i) a comonomer content of 4.0 to 17.0 mol%, and / or ii) 7.0 to 25.0 wt.-%, based on the total weight of the heterophasic propylene copolymer HECO, of a xylene cold soluble fraction XCS.

9. The flame retardant polypropylene composition C according to claim 8, wherein The xylene cold soluble fraction XCS of the heterophasic propylene copolymer HECO has: i) a comonomer content of 25.0 to 65.0 mol%, and / or ii) an intrinsic viscosity IV of less than 3.5 dl / g, measured in decalin at 135°C according to ISO 1628 / 1.

10. The flame retardant polypropylene composition C according to claim 1 or 2, wherein: The high melt strength polypropylene HMS-PP has a melt flow rate MFR2 measured according to ISO 1133 at 230° C. and a load of 2.16 kg of 0.5 to 15.0 g / 10 min.

11. The flame retardant polypropylene composition C according to claim 1 or 2, wherein: The flame retardant polypropylene composition C has a melt flow rate MFR2 of 1.0 to 30.0 g / 10 min, measured at 230° C. and a load of 2.16 kg according to ISO 1133.

12. An article comprising the flame retardant polypropylene composition C according to any one of claims 1 to 11.

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