Flame-retardant polypropylene composition

Abstract

The present invention relates to a composition comprising: (A) 45-75% of at least one heterophasic propylene copolymer comprising a propylene-based matrix and a dispersed ethylene-alpha-olefin copolymer wherein the propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer, the propylene copolymer consists of at least 90% by weight of propylene monomer units and up to 10% by weight of ethylene and / or alpha-olefin monomer units, based on the total weight of the propylene-based matrix, (B) 2-25% by weight of at least one ethylene-alpha-olefin copolymer having a density of up to 0.925 g / cm3; (C) 20-30% by weight of a flame retardant composition comprising at least one phosphate ester / salt; and (D) 0.1 to 10 wt% of an aromatic phosphoric acid ester.

Description

[0001] The present invention relates to a composition comprising a heterophasic propylene copolymer, a process for obtaining such a composition and an article, in particular an extruded article, such as a wire or cable jacketing, comprising such a composition.

[0002] Cable jacketing surrounds the cables and wires in an assembly, protecting them from chemicals, moisture, flame, and physical impact. The damage-resistant material can be constructed of thermoplastics (which melt at high temperatures and reform upon cooling) or thermosets (which retain their shape even after heating).

[0003] Conventional thermoplastic materials include polyvinyl chloride (PVC), polyurethane (PU), polyethylene (PE), and polypropylene (PP), while conventional thermoset materials include ethylene propylene rubber (EPR) and neoprene.

[0004] PP can reach a melting point of approximately 150°C (different grades have different melting points), approximately 40%-50% higher than PE, and has a long-term operating temperature of approximately 90°C. Good heat resistance is crucial for increasing the operating temperature and voltage of cables. Polypropylene is a non-polar material with high breakdown strength (mostly around 300 kV / mm), high volume resistivity (mostly around 1016 Ω·m), and little temperature variation. This can increase cable operating voltage, enhance line transmission capacity, and reduce transmission losses at the same insulation thickness. Polypropylene exhibits low space charge accumulation and a higher threshold electric field for charge injection. Polypropylene absorbs little water, so its insulation properties are less affected by ambient humidity.

[0005] Polypropylene used to produce cable sheaths should have good flame retardancy, good mechanical properties (especially impact strength) and good tensile elongation.

[0006] There remains a need in the industry to develop PP compositions having an improved balance of the above-mentioned properties.

[0007] It is an object of the present invention to provide a flame retardant composition having improved tensile elongation properties.

[0008] Another object of the present invention is to provide a flame retardant composition having an improved balance between good flame retardancy, good mechanical properties, in particular impact strength, and good tensile elongation properties.

[0009] Therefore, the present invention provides a composition comprising, based on its total weight:

[0010] (A) 45 to 75% of at least one heterophasic propylene copolymer comprising a propylene-based matrix and dispersed ethylene-α-olefin copolymer, wherein the propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer consisting of at least 90 wt.-% propylene monomer units and at most 10 wt.-% ethylene and / or α-olefin monomer units, based on the total weight of the propylene-based matrix;

[0011] (B) 2-25% by weight of at least one material having a maximum of 0.925 g / cm 3 Ethylene-α-olefin copolymer having a density of

[0012] (C) 20-30 wt. % of a flame retardant composition comprising at least one phosphate; and

[0013] (D) 0.1-10 wt% of an aromatic phosphoric acid ester.

[0014] Surprisingly, it was found that the compositions according to the invention have an improved balance between good flame retardancy, good mechanical properties, in particular impact strength, and good tensile elongation properties.

[0015] (A) Heterophasic propylene copolymer

[0016] Heterophasic propylene copolymers are generally produced in one or more reactors by polymerizing propylene in the presence of a catalyst and subsequently polymerizing an ethylene-α-olefin mixture. The resulting polymeric material is heterophasic, but the specific morphology generally depends on the production process and monomer ratios used.

[0017] The heterophasic propylene copolymers employed in the present invention can be produced using any conventional technique known to those skilled in the art, for example, a multistage process polymerization such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization, or any combination thereof. Any conventional catalyst system can be used, for example, Ziegler-Natta or metallocene. Such techniques and catalysts are described, for example, in WO 06 / 010414; Polypropylene and other Polyolefins, Ser van der Ven, Studies in Polymer Science 7, Elsevier 1990; WO 06 / 010414; US Pat. No. 4,399,054 and US Pat. No. 4,472,524.

[0018] Preferably, the heterophasic propylene copolymer is prepared using a Ziegler-Natta catalyst.

[0019] The heterophasic propylene copolymer may be prepared by a process comprising:

[0020] - polymerizing propylene and optionally ethylene and / or α-olefins in the presence of a catalyst system to obtain a propylene-based matrix, and

[0021] - Subsequently polymerizing ethylene and α-olefins in a propylene-based matrix in the presence of a catalyst system to obtain a dispersed ethylene-α-olefin copolymer. These steps are preferably carried out in different reactors. The catalyst systems of the first and second steps can be different or the same.

[0022] The heterophasic propylene copolymers of the compositions of the present invention comprise a propylene-based matrix and dispersed ethylene-α-olefin copolymers. The propylene-based matrix typically forms the continuous phase in the heterophasic propylene copolymer. As is well known in the art, the amount of the propylene-based matrix and dispersed ethylene-α-olefin copolymer can be varied by 13 C-NMR determination.

[0023] The propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer consisting of at least 90 wt% of propylene monomer units and up to 10 wt% of comonomer units selected from ethylene monomer units and α-olefins having 4 to 10 carbon atoms, e.g. at least 95 wt% of propylene monomer units and up to 5 wt% of comonomer units, based on the total weight of the propylene-based matrix.

[0024] Preferably, the comonomer in the propylene copolymer of the propylene based matrix is selected from the group consisting of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene, and is preferably ethylene.

[0025] Preferably, the propylene-based matrix consists of a propylene homopolymer.Compared to the case where the propylene-based matrix is a propylene-α-olefin copolymer, it is advantageous that the propylene-based matrix consists of a propylene homopolymer because higher rigidity is obtained.

[0026] Melt flow index (MFI) of the propylene based matrix (before mixing the heterophasic propylene copolymer into the composition of the present invention) MFI PP It may be, for example, at least 0.1 dg / min, at least 0.2 dg / min, at least 0.3 dg / min, at least 0.5 dg / min and / or, for example, at most 20 dg / min, at most 10 dg / min, at most 5.0 dg / min, at most 3.0 dg / min, at most 1.0 dg / min, measured according to ISO 1133 (2.16 kg / 230°C).

[0027] Preferably, the propylene based matrix is present in an amount of 60 to 98 wt%, such as up to 97 wt%, up to 96 wt%, up to 95 wt%, up to 93 wt% or up to 91 wt%, based on the total heterophasic propylene copolymer. Preferably, the propylene based matrix is present in an amount of at least 70 wt%, more preferably at least 75 wt%, such as at least 80 wt%, at least 85 wt%, at least 87 wt% or at least 90 wt%, based on the total heterophasic propylene copolymer.

[0028] The propylene-based matrix is preferably semi-crystalline, i.e., it is neither 100% amorphous nor 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, such as at least 50%, such as at least 60% crystalline, and / or such as at most 80% crystalline, such as at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60 to 70%. For the purposes of the present invention, the crystallinity of the propylene-based matrix is measured using differential scanning calorimetry (DSC) according to ISO 11357-1 and ISO 11357-3, 1997, using a scan rate of 10°C / min, a 5 mg sample, and a second heat curve using 207.1 J / g as a theoretical standard for 100% crystalline material.

[0029] In addition to the matrix based on propylene, the heterophasic propylene copolymer also comprises dispersed ethylene-alpha-olefin copolymer. Dispersed ethylene-alpha-olefin copolymer is also referred to as " dispersed phase" in this article. Dispersed phase embeds the heterophasic propylene copolymer in a discontinuous form. The particle size of dispersed phase is usually in the range of 0.05 to 2.0 microns, as can be measured by transmission electron microscope (TEM). The amount of dispersed ethylene-alpha-olefin copolymer in the heterophasic propylene copolymer can sometimes be referred to as RC in this article.

[0030] Preferably, the amount of ethylene monomer units in the ethylene-α-olefin copolymer is 10-60 wt%, preferably 20-58 wt%, 30-55 wt% or 40-52 wt%. The amount of ethylene monomer units in the ethylene-α-olefin copolymer dispersed in the heterophasic propylene copolymer may sometimes be referred to herein as RCC2.

[0031] The α-olefin in the ethylene-α-olefin copolymer is preferably selected from the group of α-olefins having 3 to 8 carbon atoms. Examples of suitable α-olefins having 3 to 8 carbon atoms include, but are not limited to, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. More preferably, the α-olefin in the ethylene-α-olefin copolymer is selected from the group of α-olefins having 3 to 4 carbon atoms and any mixture thereof, more preferably the α-olefin is propylene, in which case the ethylene-α-olefin copolymer is an ethylene-propylene copolymer.

[0032] The MFI of the dispersed ethylene α-olefin copolymer (before mixing the heterophasic propylene copolymer into the composition of the present invention) (MFI rubber) may be, for example, at least 0.001 dg / min, at least 0.03 dg / min or at least 0.05 dg / min, and / or, for example, at most 0.1 dg / min or 0.01 dg / min. The MFI rubber is calculated according to the following formula:

[0033]

[0034] wherein MFI Heterogeneous is the MFI (dg / min) of the heterophasic propylene copolymer measured according to ISO 1133-1:2011 (2.16 kg / 230°C), MFI Matrix is the MFI (dg / min) of the propylene-based matrix measured according to ISO 1133-1:2011 (2.16 kg / 230°C), Matrix Content is the fraction of the propylene-based matrix in the heterophasic propylene copolymer, and Rubber Content is the fraction of the dispersed ethylene-α-olefin copolymer in the heterophasic propylene copolymer. The sum of Matrix Content and Rubber Content is 1. For the avoidance of any doubt, Log in the formula means log 10 .

[0035] Preferably, the dispersed ethylene alpha-olefin copolymer is with 2.0 to 40 wt % based on total heterophasic propylene copolymer, for example at least 3.0 wt %, at least 4.0 wt %, at least 5.0 wt %, at least 7.0 wt % or at least 9.0 wt % amount exists. Preferably, the dispersed ethylene alpha-olefin copolymer is with at most 30 wt %, more preferably at most 25 wt %, for example at most 20 wt %, at most 15 wt %, at most 13 wt % or at most 10 wt % amount exists based on total heterophasic propylene copolymer. This results in good mechanical properties according to the composition of the present invention, for example impact strength.

[0036] In the heterophasic propylene copolymer of the composition of the present invention the sum of the total weight of the propylene based matrix and the dispersed ethylene α-olefin copolymer may be at least 95 wt%, at least 97 wt%, at least 99 wt% or 100 wt% of the heterophasic propylene copolymer.

[0037] Preferably the heterophasic propylene copolymer has a p-xylene soluble fraction (CXS) at 25°C measured according to ISO 16152:2005 of 2.0 to 40 wt%, like 9.0 to 25 wt%.

[0038] Preferably the amount of ethylene monomer units in the heterophasic propylene copolymer (sometimes referred to as TC2) is in the range of 1.0 to 20 wt.-%, such as 5.0 to 15 wt.-%, based on the heterophasic propylene copolymer.

[0039] Preferably, the heterophasic propylene copolymer has an MFI of 1.0-20 g / 10 min, e.g. 1.5-15 dg / min, 2.0-10 dg / min or 2.5-5.0 dg / min, measured according to ISO 1133-1:2011 (230°C / 2.16 kg). This leads in particular to good processability of the composition according to the invention.

[0040] Preferably, in the heterophasic propylene copolymer according to the present invention, the comonomer in the propylene-α-olefin copolymer is selected from the group consisting of ethylene and α-olefins having 4 to 10 carbon atoms, and the α-olefin in the ethylene-α-olefin copolymer is selected from the group consisting of α-olefins having 3 to 8 carbon atoms. Most preferably, in the heterophasic propylene copolymer according to the present invention, the comonomer in the propylene-α-olefin copolymer is ethylene and the α-olefin in the ethylene-α-olefin copolymer is propylene.

[0041] Preferably, the amount of (A) the heterophasic propylene copolymer relative to the inventive composition is 45-75 wt%, preferably 50-70 wt%, more preferably 55-65 wt%, even more preferably 51-63 wt% or 53-56 wt%.

[0042] In some embodiments, the flame retardant compositions of the present invention comprise two or more heterophasic propylene copolymers having different comonomers and / or MFIs.

[0043] (B) Ethylene-α-olefin copolymer

[0044] The composition of the present invention comprises (B) at least one 3 This results in a combination of good processability and good flame retardancy of the composition.

[0045] Preferably, (B) the ethylene-α-olefin copolymer, sometimes also referred to as an elastomer in the present invention, is a copolymer of ethylene and an α-olefin comonomer having 4 to 10 carbon atoms, preferably 4 to 8 carbon atoms, more preferably an acyclic monoolefin such as 1-butene, 1-pentene, 1-hexene, 1-octene or 4-methyl-1-pentene. Most preferably, the ethylene-α-olefin copolymer is an ethylene-1-octene copolymer.

[0046] The ethylene-α-olefin copolymer (B) has a maximum of 0.925 g / cm 3 , preferably 0.850-0.925g / cm 3 , more preferably 0.855-0.920g / cm 3 , more preferably 0.860-0.895g / cm 3 , more preferably 0.862-0.875g / cm 3, more preferably 0.864-0.870g / cm 3 Density. Density can be measured according to ASTM D792.

[0047] Ethylene-α-olefin copolymer (B) can be prepared using methods known in the art, for example, by using a single-site catalyst, i.e., a catalyst whose transition metal component is an organometallic compound and whose at least one ligand has a cyclopentadienyl anionic structure, through which such ligand is bonded and coordinated to the transition metal cation. This type of catalyst is also known as a "metallocene" catalyst. Metallocene catalysts are described, for example, in U.S. Patents 5,017,714 and 5,324,820. Elastomers can also be prepared using conventional types of heterogeneous multisite Ziegler-Natta catalysts.

[0048] Preferably, the (B) ethylene-α-olefin copolymer has a melt flow index measured according to ASTM D1238 using a load of 2.16 kg and a temperature of 190° C. of 1.0 to 10 dg / min, preferably 2.0 to 8.0 dg / min, more preferably 3.0 to 7.0 dg / min. This results in a combination of good mechanical properties and flame retardancy.

[0049] Preferably, the amount of (B) ethylene-α-olefin copolymer relative to the composition of the present invention is 2.0-25 wt%, preferably 5.0-18 wt%, more preferably 10-15 wt%.

[0050] (C) Flame retardant composition comprising at least one phosphate

[0051] The flame retardant composition comprises at least one phosphate, wherein the phosphate is preferably selected from the group consisting of:

[0052] Melamine Phosphate,

[0053] Melamine polyphosphate,

[0054] Melamine pyrophosphate,

[0055] Piperazine phosphate,

[0056] Piperazine polyphosphate,

[0057] Piperazine pyrophosphate,

[0058] 2-Methylpiperazine monophosphate,

[0059] Tricresyl phosphate,

[0060] Alkyl phosphate,

[0061] Haloalkyl phosphates,

[0062] Tetraphenyl pyrophosphate,

[0063] Poly(2-hydroxypropylene spirocyclopentaerythritol bisphosphate),

[0064] Poly(2,2-dimethylpropylene spirocyclic pentaerythritol bisphosphonate).

[0065] The flame retardant composition is preferably in the form of particles.Preferably, the flame retardant composition has a normal particle size distribution (D50) of at least 8 microns as measured by a Mastersizer 2000 available from Malvern.

[0066] Preferably, the amount of phosphate in the flame retardant composition is 40-75 wt %, as measured using an ICP-OES spectrometer (iCAP 6300 Duo available from Thermo Fisher) after treatment with nitric acid.

[0067] Preferably, the flame retardant composition comprises piperazine pyrophosphate, melamine phosphate and zinc oxide.

[0068] Preferably, the amount of piperazine pyrophosphate is 40-69 wt%, more preferably 50-67 wt%, the amount of melamine phosphate is 29-49 wt% and the amount of zinc oxide is 1-10 wt%, based on the total amount of the flame retardant composition.

[0069] Preferably, the amount of (C) flame retardant composition comprising at least one phosphate ester / salt relative to the composition of the present invention is 20-30 wt %, preferably 21-28 wt %, more preferably 22-27 wt %, even more preferably 23-26 wt %, and most preferably 24-25 wt %.

[0070] (D) Aromatic phosphates

[0071] Preferably, the aromatic phosphate is selected from the group consisting of:

[0072] Resorcinol bis(diphenyl phosphate);

[0073] Tetraphenylresorcinol bis(diphenyl phosphate);

[0074] Bisphenol A bis(diphenyl phosphate);

[0075] Bisphenol A diphosphate;

[0076] Resorcinol bis(di-2,6-ditolyl phosphate),

[0077] Mixed esters of phosphoric acid, [1,1'-biphenyl]-4-4'-diol and phenol;

[0078] Phosphorus trichloride, polymer with 1,3-benzenediol, phenyl ester;

[0079] 1,3-phenylene-tetrakis(2,6-dimethylphenyl)diphosphate;

[0080] Isopropenylphenyl diphenyl phosphate;

[0081] 4-Phenylphenol formaldehyde phenylphosphonate;

[0082] Tris(2,6-dimethylphenyl)phosphate;

[0083] Resorcinol bis(di-2,6-ditolyl phosphate);

[0084] Bisphenol S bis(diphenyl phosphate);

[0085] Resorcinol-bisphenol A phenyl phosphate.

[0086] Preferably, the aromatic phosphate is added in liquid form in the process for producing the composition according to the invention.

[0087] Preferably, the aromatic phosphate is bisphenol A bis(diphenyl phosphate).

[0088] Preferably, the amount of (D) aromatic phosphate is 0.1-10 wt %, preferably 1.0-6.0 wt %, more preferably 2.0-4.0 wt % relative to the composition of the present invention.

[0089] Preferably, the total amount of components (A), (B), (C) and (D) is at least 90 wt%, at least 95 wt%, at least 97 wt%, at least 98 wt%, at least 99 wt%, at least 99.5 wt%, at least 99.9 wt% or 100 wt% of the total composition.

[0090] (E) Additives

[0091] The composition according to the present invention may optionally contain additives. The additives may include nucleating agents; stabilizers, such as heat stabilizers, antioxidants, UV stabilizers; colorants, such as pigments and dyes; clarifying agents; surface tension modifiers; lubricants; flame retardants; mold release agents; flow improvers; plasticizers; antistatic agents; and foaming agents.

[0092] The skilled person can readily select any suitable combination of additives and amounts without undue experimentation. The amount of the additives depends on their type and function and is typically from 0 to about 10 weight %. The amount of the additive can be, for example, from about 0.1 to about 5 weight % based on the total composition; from about 1 to about 4 weight % or from 1.5 to about 3 weight %. The total amount of (A), (B), (C), (D) and (E) should add up to 100 weight %.

[0093] Composition

[0094] Preferably, the composition has a melt flow index measured according to ISO 1133-1:2011 using a 2.16 kg load at 230°C of 1.0 to 10 dg / min, preferably 1.5 to 5.0 dg / min.

[0095] Preferably, the composition has a UL94 rating of V-0 at 0.8 mm, wherein the UL94 measurements are made on specimens that have been conditioned in a first environment of 70°C, 50% RH for 168 hours and then in a second environment of 23°C, 20% RH for 4 hours.

[0096] In other aspects

[0097] The composition of the present invention can be obtained by a process comprising melt mixing (A), (B), (C), (D) and optionally (E) using any suitable means. Therefore, the present invention further relates to a process for preparing a composition according to the present invention, said process comprising melt mixing (A), (B), (C), (D) and optionally (E).

[0098] Preferably, the composition of the present invention is prepared in a form that allows for easy processing into shaped articles in a subsequent step, such as in the form of pellets or granules. The composition may be a mixture of different pellets or granules, such as a blend of (A), (B), (C), (D) and a masterbatch of additives. Preferably, the composition of the present invention is in the form of pellets or granules, such as obtained by mixing all the components in a device such as an extruder; advantageously, the composition has a uniform and well-defined concentration of additives.

[0099] Melt mixing can be performed using techniques known to the skilled person, for example in an extruder. Generally speaking, in the process of the present invention, melt mixing is performed at a temperature in the range of 200-260°C.

[0100] When using an extruder, suitable conditions for melt mixing, such as temperature, pressure, amount of shear, screw speed and screw design are known to the skilled person.

[0101] The compositions according to the invention can be processed by known processing methods, in particular extrusion.

[0102] The present invention also relates to an article, in particular an extruded article, comprising the composition according to the invention. Preferably, the article is a wire or cable sheath. Preferably, the article is a cable comprising a conductor and an insulation layer, wherein the insulation layer comprises the composition according to the invention.

[0103] It should be noted that the present invention relates to the subject matter defined in the independent claims, alone or in combination with any possible combination of the features described herein, preferably in particular those combinations of the features presented in the claims. It will therefore be understood that all combinations of features relating to the composition according to the invention, all combinations of features relating to the method according to the invention, and all combinations of features relating to the composition according to the invention and of features relating to the method according to the invention are described herein.

[0104] It should also be noted that the terms "comprising," "including," and "containing" do not exclude the presence of other elements. However, it should also be understood that a description of a product / composition comprising certain components also discloses a product / composition consisting of these components. A product / composition consisting of these components may be advantageous because it provides a simpler, more economical method for preparing the product / composition. Similarly, it should be understood that a description of a method comprising certain steps also discloses a method consisting of these steps. A method consisting of these steps may be advantageous because it provides a simpler, more economical method.

[0105] When values are stated for a lower limit and an upper limit for a parameter, it is understood that the range resulting from the combination of the value for the lower limit and the value for the upper limit is also disclosed.

[0106] The present invention is now illustrated with the aid of the following examples, without however being restricted thereto.

[0107] experiment

[0108] Material

[0109] Heterophasic PP1 is a heterophasic propylene copolymer commercially available from SABIC as 95MK40T having an MFI of 3.5 g / 10 min, measured according to ISO 1133:1-2011 at 230° C., 2.16 kg. 95MK40T has a propylene homopolymer matrix and 21 wt.-% dispersed ethylene-propylene copolymer, the total amount of moieties derived from ethylene in 95MK40T being 10.5 wt.-%, determined by NMR.

[0110] Heterophasic PP2 is a heterophasic propylene copolymer commercially available from LyondellBasell as EP5079 with an MFI of 0.5 g / 10 min measured according to ASTM D1238 at 230°C and 2.16 kg.

[0111] POE is an ethylene-1-octene copolymer, which is manufactured by SABIC under the name FORTIFY TMElastomer C5070T is commercially available with an MFI of 5.0 dg / min measured according to ASTM D1238 at 190°C, 2.16 kg and a viscosity of 0.868 g / cm 3 Density measured according to ASTM D792.

[0112] LLDPE is an ethylene-1-butene copolymer commercially available from SABIC as LLDPE 218NT, having an MFI of 2.0 dg / min measured according to ASTM D1238 at 190°C, 2.16 kg and a viscosity of 0.918 g / cm 3 Density measured according to ASTM D792.

[0113] FP2500S is a flame retardant composition comprising at least one phosphate ester / salt according to a preferred embodiment of the present invention, commercially available from Adeka as ADK STAB FP-2500S.

[0114] BPADP is bisphenol A bis(diphenyl phosphate), commercially available from Daihachi.

[0115] Additive Package: The additive package contains 33 wt% of stabilizer, 17 wt% of anti-drip agent (SABIC's TSAN F449), 8 wt% of slip agent and 42 wt% of masterbatch. The weight percentages are based on the total amount of the additive package.

[0116] nature

[0117] Melt flow index (MFI) is measured according to ISO 1133: 1-2011 at 230°C, 2.16 kg.

[0118] Tensile properties were measured according to ISO 527-1:2019 using 1A specimens.

[0119] Density is measured according to ISO 1183-1:2004.

[0120] The Charpy notched impact strength was measured according to ISO 179 / 1eA(II) at 23° C. (RT) and at −20° C. after 7 days.

[0121] Flame retardancy measurements were performed according to UL94. Specimens of varying thickness were used; prior to measurement, the specimens were conditioned under the following conditions:

[0122] After injection molding and before flame retardancy measurement, the test specimens were conditioned in a first environment of 70° C., 50% RH for 168 hours and then in a second environment of 23° C., 20% RH for 4 hours.

[0123] The components shown in Table 1 and Table 2 were melt-mixed in a twin-screw extruder to obtain pellets. The pellets were further injection-molded into test specimens for measuring the properties shown in the table.

[0124] Table 1

[0125]

[0126] Table 2

[0127]

[0128] As the content of the flame retardant composition FP2500S increases, not only the flame retardancy of the composition is improved, but also the Charpy impact strength and extrusion processability are improved, especially the tensile elongation property is unexpectedly improved, as can be seen from the comparison of Ex7 with Ex9, Ex8 with Ex10, and Ex11 with Ex12.

[0129] The large difference between the tensile strength at break and the tensile strength at yield, ie, TS@B-TS@Y, indicates a high degree of strain hardening, i.e., improved processability during extrusion.

[0130] Ex2 to Ex4 (containing POE (ethylene-octene copolymer)) show a high degree of strain hardening. Ex2 and Ex3 show a combination of a high degree of strain hardening and excellent flame retardancy. Ex3 and Ex4 show a particularly high degree of strain hardening.

[0131] Comparing Ex 2-4 and Ex 5-8 with each other, respectively, it can be understood that a higher amount of POE or LLDPE results in a lower MFI, a higher Charpy impact strength, a higher degree of strain hardening, and a higher tensile elongation.

[0132] Ex3, Ex9, Ex10 and Ex12 achieve the best balance between high Charpy impact strength, high strain hardening, high tensile elongation and excellent flame retardancy.

Claims

1. A composition comprising, based on its total weight: (A) 45 to 75% of at least one heterophasic propylene copolymer comprising a propylene-based matrix and dispersed ethylene-α-olefin copolymer, wherein the propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer consisting of at least 90 wt.-% propylene monomer units and at most 10 wt.-% ethylene and / or α-olefin monomer units, based on the total weight of the propylene-based matrix; (B) 2-25% by weight of at least one material having a maximum of 0.925 g / cm 3 Ethylene-α-olefin copolymer having a density of (C) 20-30 wt. % of a flame retardant composition comprising at least one phosphate; and (D) 0.1-10 wt% of an aromatic phosphoric acid ester.

2. The composition according to any one of the preceding claims, wherein the amount of (A) is 50-70 wt%, preferably 55-65 wt%.

3. The composition according to any one of the preceding claims, wherein (B) has a melt flow index measured according to ISO 1133-1:2011 at 2.16 kg and 190°C of 1.0-10 dg / min, preferably 2.0-8.0 dg / min, more preferably 3.0-7.0 dg / min.

4. A composition according to any one of the preceding claims, wherein the amount of (B) is 5-18 wt%, preferably 10-15 wt%.

5. The composition according to any one of the preceding claims, wherein (B) is an ethylene-1-octene copolymer.

6. The composition according to any one of the preceding claims, wherein the amount of (C) is 21-28 wt%, preferably 22-27 wt%, more preferably 23-26 wt%, and even more preferably 24-25 wt%.

7. The composition according to any one of the preceding claims, wherein (C) comprises piperazine pyrophosphate, melamine phosphate and zinc oxide, preferably wherein the amount of piperazine pyrophosphate is 40-69 wt%, preferably 50-67 wt%, the amount of melamine phosphate is 29-49 wt%, and the amount of zinc oxide is 1-10 wt%, based on the total amount of the flame retardant composition.

8. A composition according to any one of the preceding claims, wherein the amount of (D) is 1-6 wt%, preferably 2-4 wt%.

9. The composition according to any one of the preceding claims, wherein (D) is selected from the group consisting of: Resorcinol bis(diphenyl phosphate); Tetraphenylresorcinol bis(diphenyl phosphate); Bisphenol A bis(diphenyl phosphate); Bisphenol A diphosphate; Resorcinol bis(di-2,6-ditolyl phosphate), Mixed esters of phosphoric acid, [1,1'-biphenyl]-4-4'-diol and phenol; Phosphorus trichloride, polymer with 1,3-benzenediol, phenyl ester; 1,3-phenylene-tetrakis(2,6-dimethylphenyl)diphosphate; Isopropenylphenyl diphenyl phosphate; 4-Phenylphenol formaldehyde phenylphosphonate; Tris(2,6-dimethylphenyl)phosphate; Resorcinol bis(di-2,6-ditolyl phosphate); Bisphenol S bis(diphenyl phosphate); and Resorcinol-bisphenol A phenyl phosphate, Preferably, the aromatic phosphate is bisphenol A bis(diphenyl phosphate).

10. The composition of any one of the preceding claims, wherein the total amount of (A), (B), (C) and (D) is at least 90 wt%, at least 95 wt%, at least 98 wt%, at least 99 wt% or 100 wt% relative to the total composition.

11. The composition according to any one of the preceding claims, wherein the composition has a melt flow index measured according to ISO 1133-1:2011 at 2.16 kg and 230°C of 1.0-10 dg / min, preferably 1.5-5.0 dg / min.

12. The composition of any preceding claim, wherein the composition has a UL94 rating of V-0 at 0.8 mm, wherein the UL94 measurement is performed on specimens that have been conditioned in a first environment of 70°C, 50% RH for 168 hours and then in a second environment of 23°C, 20% RH for 4 hours.

13. A process for preparing a composition according to any one of the preceding claims, comprising melt mixing components (A) to (D).

14. An article comprising the composition according to any one of claims 1 to 12, preferably an extruded article produced by extruding the composition, preferably a wire or cable jacketing.

15. Use of the composition according to any one of claims 1 to 12 for the manufacture of wire or cable sheathing.

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