Propylene-based copolymer composition for pipes

Abstract

A) from 85% to 99.0% by weight of a propylene homopolymer; B) from 1.0% to 15.0% by weight of a propylene, ethylene copolymer composition comprising: b1) from 24% to 54% by weight of a propylene homopolymer; b2) from 46% to 76% by weight of a propylene ethylene copolymer.

Description

Technical Field

[0001] This disclosure relates to a composition comprising a propylene homopolymer and a heteropolymer propylene-ethylene copolymer, which is particularly suitable for the production of sewage pipes with relatively high impact at low temperatures to ensure installation under low-temperature conditions. Background Technology

[0002] Propylene-ethylene copolymers are known in the art to be used in the production of pipes.

[0003] For example, according to international patent application WO 97 / 33117, pipes made of polypropylene plastic materials with high creep resistance, high long-term pressure resistance, improved stiffness, and resistance to rapid crack propagation can be obtained. According to the aforementioned document, catastrophic failure of the polypropylene plastic pipe can be prevented when it is made of several layers of different polypropylene plastic materials, wherein at least one layer consists of a wide molecular weight distribution (MWD) polypropylene providing high creep resistance, and at least one layer consists of an elastomer-modified polypropylene with improved impact strength. The wide MWD polypropylene is a mixture of an extremely high molecular weight propylene random copolymer having 1% to 10% by weight of ethylene or higher α-olefin repeating units and a low molecular weight propylene polymer having low (at most 1% by weight) or zero comonomers.

[0004] Limiting the wall thickness of pipes is important. This allows for pipes with less material and lighter weight, and improves feeding efficiency due to the larger inner diameter (primarily for smaller diameter pipe applications). However, as the wall thickness decreases, the pipe becomes brittle, necessitating the use of materials with high impact resistance, especially at low temperatures. Furthermore, the material used for the pipe must have a high flexural modulus to achieve a rigid pipe. Typically, in polypropylene-based compositions, the flexural modulus decreases as impact performance increases. The applicant has discovered that adding small amounts of a heterogeneous copolymer with specific characteristics to a propylene-ethylene copolymer can achieve a good impact / stiffness balance and improved pressure resistance. Summary of the Invention

[0005] The purpose of this disclosure is to provide a polyolefin composition comprising:

[0006] A) 85% to 99.0% by weight of a propylene homopolymer, wherein the propylene homopolymer has:

[0007] (i) Polydispersion index in the range of 5 to 10

[0008] (ii) 4.0% to 1.0% by weight of xylene soluble in xylene at 25°C;

[0009] (iii) Melt flow rate in the range of 0.2 g / 10 min to 3.5 g / 10 min (230 °C / 5 kg..ISO 1133);

[0010] B) A propylene-ethylene copolymer composition comprising 1.0% to 15.0% by weight, wherein the propylene-ethylene copolymer composition has the following characteristics:

[0011] i) Fractions ranging from 35% to 61% by weight that are soluble in xylene at 25°C;

[0012] ii) Melt flow rate ranging from 0.1 g / 10 min to 2.0 g / 10 min (230 °C / 2.16 kg..ISO 1133)

[0013] iii) The intrinsic viscosity of the fraction that is soluble in xylene at 25°C, measured in naphthalene, ranges from 2.2 dl / g to 5.7 dl / g;

[0014] iv) The content of ethylene-derived units ranges from 25.5% to 46.3% by weight;

[0015] Component B of the propylene-ethylene copolymer composition comprises:

[0016] b1) 24% to 54% by weight of propylene homopolymer, said propylene homopolymer having a melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) in the range of 2.0 g / 10 min to 19.0 g / 10 min;

[0017] b2) 46% to 76% by weight of a propylene-ethylene copolymer, wherein the propylene-ethylene copolymer has an ethylene-derived unit content ranging from 40.7% to 77.5% by weight;

[0018] The polyolefin composition has the following characteristics: a melt flow rate ranging from 0.4 g / 10 min to 4.0 g / 10 min (230 °C / 5 kg ISO 1133); the amounts of A+B are 100% by weight and the amounts of b1+b2 are 100% by weight. Detailed Implementation

[0019] Therefore, the object of this disclosure is a polyolefin composition comprising:

[0020] A) 85.0% to 99.0% by weight; preferably 90% to 98.5% by weight; more preferably 93% to 98% by weight of a propylene homopolymer, the propylene homopolymer having:

[0021] (i) Polydispersion index in the range of 5 to 10

[0022] (ii) 4.0% to 1.0% by weight; preferably 3.0% to 2.0% by weight of the soluble matter in xylene at 25°C;

[0023] (iii) A melt flow rate ranging from 0.2 g / 10 min to 3.5 g / 10 min; preferably from 0.6 g / 10 min to 2.0 g / 10 min (230 °C / 5 kg..ISO 1133);

[0024] B) 1.0% to 15.0% by weight; preferably 1.5% to 10.0% by weight; more preferably 2.0% to 7.0% by weight of a propylene-ethylene copolymer composition, wherein the propylene-ethylene copolymer composition has:

[0025] i) a fraction ranging from 35% to 61% by weight; preferably from 38% to 58% by weight; more preferably from 43% to 54% by weight of a fraction that is soluble in xylene at 25°C;

[0026] ii) A melt flow rate ranging from 0.1 g / 10 min to 1.0 g / 10 min; preferably from 0.2 g / 10 min to 1.6 g / 10 min; more preferably from 0.3 g / 10 min to 1.4 g / 10 min (230°C / 2.16 kg..ISO 1133);

[0027] iii) The intrinsic viscosity of the fraction that is soluble in xylene at 25°C, as measured in naphthalene, is in the range of 2.2 dl / g to 5.7 dl / g; preferably 2.4 dl / g to 5.2 dl / g; more preferably 2.7 dl / g to 4.7 dl / g.

[0028] iv) The content of ethylene-derived units ranges from 25.5% to 46.3% by weight; preferably from 27.4% to 43.9% by weight; more preferably from 30.3% to 42.2% by weight.

[0029] The propylene-ethylene copolymer composition comprises:

[0030] b1) 24 wt% to 54 wt%; preferably 29 wt% to 49 wt%; more preferably 32 wt% to 46 wt% of propylene homopolymer, the propylene homopolymer having a melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) in the range of 2.0 g / 10 min to 19.0; preferably 4.0 g / 10 min to 17.0 g / 10 min; more preferably 6.0 g / 10 min to 15.0 g / 10 min;

[0031] b2) 46% to 76% by weight; preferably 51% to 71% by weight; more preferably 54% to 68% by weight of a propylene-ethylene copolymer having an ethylene-derived unit content ranging from 40.7% to 77.5% by weight; preferably from 46.8% to 71.3% by weight; more preferably from 50.8% to 67.3% by weight.

[0032] The polyolefin composition has a melt flow rate (230°C / 5kg..ISO1133) ranging from 0.4 g / 10 min to 4.0 g / 10 min; preferably from 0.7 g / 10 min to 3.2 g / 10 min; more preferably from 1.0 g / 10 min to 2.7 g / 10 min.

[0033] The amounts of A+B are the sum of 100% by weight, and the amounts of b1+b2 are the sum of 100% by weight.

[0034] The term copolymer refers to a polymer containing only two monomers; preferably propylene and ethylene.

[0035] The polyolefin compositions disclosed herein preferably exhibit a range of 50.0 KJ / m² at 23°C as measured according to ISO 179-1:2010. 2 Up to 80.0 KJ / m 2 The preferred range is 55.0 KJ / m³. 2 Up to 75.0 KJ / m 2 Even more preferably, the range is 60.0 KJ / m 2 Up to 70.0 KJ / m 2 Charpy impact test. The tensile modulus of the polyolefin compositions of this disclosure, as determined according to ISO 527-2, ranges from 1600 MPa to 2500 MPa; preferably from 1700 MPa to 2300 MPa; even more preferably from 1800 MPa to 2200 MPa. The flexural modulus of the polyolefin compositions of this disclosure, as determined according to ISO 178:2019, ranges from 1600 MPa to 2400 MPa; preferably from 1700 MPa to 2300 MPa; even more preferably from 1800 MPa to 2200 MPa.

[0036] Preferably, component A) has one or more of the following characteristics:

[0037] i) A flexural modulus in the range of 1500 MPa to 2300 MPa as determined by method ISO 178:2019; preferably in the range of 1800 MPa to 2200 MPa;

[0038] ii) The range of 3.0 kJ / m³ measured according to ISO 180 / A for specimens injection molded according to ISO 1873-2. 2 Up to 6.0 kJ / m 2 The preferred range is 3.8 kJ / m³. 2 Up to 5.3 kJ / m 2 The Ezod impact test at 0°C;

[0039] iii) The melting point measured by DSC is in the range of 155°C to 170°C, preferably in the range of 160°C to 167°C.

[0040] Using the polyolefin compositions disclosed herein, pipes with high modulus, high impact resistance and improved pressure resistance can be obtained, especially sewage pipes.

[0041] Therefore, another object of this disclosure is a conduit comprising the compositions of this disclosure.

[0042] As used herein, the term "pipe" also includes pipe fittings, valves, and all components typically required for systems such as hot water piping. The definition also includes single-layer and multi-layer pipes, where one or more layers are, for example, metallic layers and may include adhesive layers.

[0043] Such articles can be manufactured by various industrial methods well known in the art, such as molding, extrusion, etc.

[0044] The compositions disclosed herein may also contain an inorganic filler in an amount ranging from 0.5 parts by weight to 60 parts by weight relative to 100 parts by weight of the composition. Typical examples of such fillers are calcium carbonate, barium sulfate, titanium dioxide, and talc. Talc and calcium carbonate are preferred. Many fillers may also have a nucleating effect, such as talc, which is also a nucleating agent. The amount of nucleating agent is typically from 0.2% to 5% by weight relative to the amount of polymer.

[0045] The compositions disclosed herein are also suitable for providing pipes having walls with any configuration other than those having smooth inner and outer surfaces. Examples are pipes with sandwich-like pipe walls, pipes with hollow wall structures having longitudinally extending cavities, pipes with hollow wall structures having helical cavities, and pipes having smooth inner surfaces and compact or hollow, helical or annular ribbed outer surfaces, regardless of the configuration of the respective pipe ends.

[0046] Articles, pressure pipes and related fittings according to this disclosure are manufactured in a manner known per se, such as by (co)extrusion or molding.

[0047] The extrusion of the product can be carried out using different types of polyolefin extruders (e.g., single-screw or twin-screw extruders).

[0048] Furthermore, another object of this disclosure is a method for molding the polyolefin composition of this disclosure into said article.

[0049] When the conduit is multilayered, at least one layer is made of the above-described polyolefin composition. The additional layers are made of amorphous or crystalline polymers of R-CH=CH2 olefins (such as homopolymers and copolymers or terpolymers), wherein R is a hydrogen atom or a C1-C6 alkyl radical. Particularly preferred polymers are:

[0050] Isotropic or predominantly isotactic propylene homopolymers;

[0051] Random copolymers and terpolymers of propylene with ethylene and / or C4-C8 α-olefins (such as 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene), wherein the total monomer content ranges from 0.05% by weight to 20% by weight, or the polymer is a mixture with isotactic or predominantly isotactic propylene homopolymers.

[0052] A heterogeneous polymer blend comprising: (a) a propylene homopolymer, and / or a copolymer of item (2) and a terpolymer; and an elastomer portion (b) comprising a copolymer of ethylene with propylene and / or a C4-C8 α-olefin and a terpolymer (optionally containing trace amounts of diene, the same substance disclosed for polymer (2)(a)); and

[0053] Amorphous polymers, such as fluorinated polymers and polydifluoroethylene (PVDF).

[0054] In multi-layered pipes, the layers of pipe can have the same or different thicknesses.

[0055] The compositions disclosed herein can be prepared by blending various components A), b1), and b2), or by preparing component A) and blending it with component B) prepared in a single polymerization process via a sequential polymerization step.

[0056] The polymerization of A) and B) can be carried out in the presence of a Ziegler-Natta catalyst. An essential component of the catalyst is a solid catalyst component comprising a titanium compound having at least one titanium-halogen bond and an electron donor compound, both supported in active form on magnesium halides. Another essential component (co-catalyst) is an organoaluminum compound, such as an alkylaluminum compound.

[0057] External donors can be added optionally.

[0058] The catalysts commonly used in the methods disclosed herein are capable of producing polypropylene with a xylene insolubility value greater than 90%, preferably greater than 95%, at ambient temperature.

[0059] Catalysts possessing the above-described features are well known in patent literature; those described in U.S. Patent 4,399,054 and European Patent 45,977 are particularly advantageous. Other examples can be found in U.S. Patent 4,472,524.

[0060] The solid catalyst components used in the catalyst include compounds selected from the group consisting of: ethers, ketones, lactones, compounds containing N, P and / or S atoms, and esters of monocarboxylic acids and dicarboxylic acids.

[0061] Particularly suitable electron donor compounds are phthalic acid esters and 1,3-diethers of the following formula:

[0062]

[0063] Wherein RI and RII are the same or different and are C1-C18 alkyl, C3-C18 cycloalkyl, or C7-C18 aryl radicals; RIII and RIV are the same or different and are C1-C4 alkyl radicals; or are 1,3-diethers, wherein the carbon atom at position 2 belongs to a cyclic or polycyclic structure composed of 5, 6, or 7 carbon atoms, or 5-n or 6-n' carbon atoms, and n nitrogen atoms and n' heteroatoms selected from the group consisting of N, O, S, and Si, where n is 1 or 2 and n' is 1, 2, or 3, and the structure contains two or three degrees of unsaturation (cyclic polycyclic). (Alkene structure), and optionally condensed with other cyclic structures, or substituted with one or more substituents selected from the group consisting of: straight-chain or branched alkyl radicals, cycloalkyl, aryl, aralkyl, alkylaryl radicals and halogens, or condensed with other cyclic structures and substituted with one or more of the above substituents, one or more of the above substituents may also be bonded to the condensed cyclic structure; one or more of the above alkyl, cycloalkyl, aryl, aralkyl or alkylaryl radicals and optionally condensed cyclic structures containing one or more heteroatoms as substituents of carbon or hydrogen atoms or both.

[0064] This type of ether is described in published European patent applications 361493 and 728769.

[0065] Representative examples of the diethers are 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, and 9,9-bis(methoxymethyl)fluorene.

[0066] Other suitable electron donor compounds are phthalic acid esters, such as diisobutyl phthalate, dioctyl phthalate, diphenyl phthalate, and benzyl butyl phthalate.

[0067] The preparation of the above catalyst components is carried out according to various methods.

[0068] For example, MgCl2·nROH adducts (especially in spherical particulate form) (where n is typically from 1 to 3 and ROH is ethanol, butanol, or isobutanol) react with an excess of TiCl4 containing an electron donor compound. The reaction temperature is typically 80°C to 120°C. The solid is then separated and reacted again with TiCl4, with or without the electron donor compound, followed by separation and washing with an aliquot of hydrocarbons until all chloride ions are removed.

[0069] In the solid catalyst composition, titanium compounds, represented as Ti, are typically present in an amount of 0.5 wt% to 10 wt%. The amount of electron donor compounds retained on the solid catalyst composition relative to magnesium dihalide is typically 5 mol% to 20 mol%.

[0070] Titanium compounds that can be used to prepare solid catalyst components are titanium halides and halogen alcohols. Titanium tetrachloride is a preferred compound.

[0071] The above reactions form magnesium halides in their active form. Other reactions are known in the literature, which begin with magnesium compounds other than halides (such as magnesium carboxylate) to form magnesium halides in their active form.

[0072] Al-alkyl compounds used as cocatalysts include Al-trialkyl compounds, such as Al-triethyl, Al-triisobutyl, Al-trin-butyl, and straight-chain or cyclic Al-alkyl compounds containing two or more Al atoms bonded to each other by O or N atoms or SO4 or SO3 groups.

[0073] Al-alkyl compounds are typically used in amounts that result in an Al / Ti ratio of 1 to 1000.

[0074] Electron donor compounds that can be used as external donors include aromatic esters, such as alkyl benzoates, and in particular silicon compounds containing at least one Si-OR bond, where R is a hydrocarbon radical.

[0075] Examples of silicon compounds are (tert-butyl)2Si(OCH3)2, (cyclohexyl)(methyl)Si(OCH3)2, (cyclopentyl)2Si(OCH3)2, (phenyl)2Si(OCH3)2, and (1,1,2-trimethylpropyl)Si(OCH3)3.

[0076] 1,3-diethers having the above chemical formula can also be advantageously used. If the internal donor is one of these diethers, the external donor can be omitted.

[0077] In particular, even though many other combinations of the aforementioned catalyst components may allow the composition according to this disclosure to be obtained, components A) and B) are preferably prepared by using a catalyst containing phthalate as an internal donor and (cyclopentyl)2Si(OCH3)2 as an external donor, or the 1,3-diether as an internal donor.

[0078] Additionally, the Ziegler-Natta catalyst that can be used to prepare the propylene polymer of this disclosure is a solid catalyst component comprising magnesium halide, a titanium compound having at least one titanium-halogen bond as described above, and at least two electron donor compounds, one of which is selected from succinates and the other from 1,3-diethers.

[0079] Component A is preferably produced using the polymerization method shown in EP application 1,012,195.

[0080] Specifically, the method includes: feeding monomers into the polymerization zone under reaction conditions in the presence of a catalyst, and collecting polymer products from the polymerization zone. In this method, grown polymer particles flow upwards through one (first) polymerization zone (riser) under rapid fluidization conditions, exit the riser and enter another (second) polymerization zone (downstream) through which they flow downwards in a densified form under gravity, exit the downstream and are reintroduced into the riser, thereby establishing a polymer circulation between the riser and the downstream.

[0081] In the downcomer, a high solids density is achieved, approaching the bulk density of the polymer. Therefore, a positive pressure gain can be obtained along the flow direction, allowing the polymer to be reintroduced into the riser without the aid of special mechanical devices. In this way, a "loop" circulation is established, defined by the pressure balance between the two polymerization zones and the head loss introduced into the system.

[0082] Typically, rapid fluidization conditions in the riser are established by feeding a gas mixture containing the relevant monomers into the riser. Preferably, the gas mixture is fed below the point where the polymer is reintroduced into the riser by using a gas distributor device where appropriate. The velocity of the delivery gas entering the riser is higher than the delivery velocity under operating conditions, preferably 2 m / s to 15 m / s.

[0083] Typically, the polymer and gas mixture exiting the riser is conveyed to a solid / gas separation zone. Solid / gas separation can be achieved using conventional separation methods. The polymer enters the downcomer from the separation zone. The gaseous mixture exiting the separation zone is compressed, cooled, and transferred to the riser, with supplementary monomers and / or molecular weight modifiers added, if appropriate. Transfer can be achieved via a gas mixture recirculation line.

[0084] Control of the polymer circulating between the two polymerization zones can be achieved by metering the amount of polymer leaving the downcomer using a device suitable for controlling solid flow, such as a mechanical valve.

[0085] The operating parameters (such as temperature) are those commonly used in olefin polymerization methods, for example, between 50°C and 120°C.

[0086] The first stage process can be carried out at an operating pressure between 0.5 MPa and 10 MPa, preferably between 1.5 MPa and 6 MPa.

[0087] Advantageously, one or more inert gases are maintained in the polymerization zone in an amount such that the sum of the partial pressures of the inert gases is preferably between 5% and 80% of the total gas pressure. The inert gases may be, for example, nitrogen or propane.

[0088] Various catalysts can be fed upwards into the riser at any point. However, they can also be fed at any point in the downcomer. The catalyst can be in any physical state, so solid or liquid catalysts can be used.

[0089] The following examples are given to illustrate this disclosure and not to limit its scope.

[0090] Example

[0091] Characterization methods

[0092] Xylene-soluble (XS) fraction at 25℃

[0093] The xylene soluble content at 25°C has been determined according to ISO 16 152.

[0094] DSC method for melting point

[0095] According to ISO 11357-3, the melting point of samples weighing between 5 mg and 7 mg was measured under cooling and heating conditions in an inert N2 flow at a scan rate of 20°C / min. Indium was used for instrument calibration.

[0096] Melt flow rate: determined according to method ISO 1133 (230°C, 5 kg or 2.16 kg).

[0097] Ethylene content in copolymers

[0098] Data were collected on a Bruker AV-600 spectrometer equipped with a cryoprobe. 13 C10 NMR spectroscopy was performed in Fourier transform mode at 160.91 MHz at 120 °C.

[0099] Sββ carbon (according to "through") 1313C NMR was used to measure the monomer sequence distribution in ethylene-propylene rubber. The peak value of the nomenclature ("Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by 13C NMR. 3. Use of Reaction Probability Mode" CJ Carman, RA Harrington, and CE Wilkes, *Macromolecules*, 1977, Vol. 10, p. 536) was used as an internal reference, with a value of 29.9 ppm. The sample was dissolved in 1,1,2,2-tetrachloroethane-d2 at 120 °C at a concentration of 8% wt / v. Each spectrum was acquired with a 90° pulse, with a 15-second delay between the pulse and the CPD to eliminate interference. 1 H- 13 C-coupling. 512 transient data points were stored in 32K data points using a 9000Hz spectral window.

[0100] According to Kakugo (“Carbon-13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with δ-titanium trichloride-diethyl-aluminum chloride”, M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, Vol. 15, p. 1150), the spectra were assigned using the following equation, and the ternary distribution and composition were evaluated:

[0101] PPP=100Tββ / S PPE=100Tβδ / S EPE=100Tδδ / S

[0102] PEP=100Sββ / S PEE=100Sβδ / S EEE=100(0.25Sγδ+0.5Sδδ) / S

[0103] S=Tββ+Tβδ+Tδδ+Sββ+Sβδ+0.25Sγδ+0.5Sδδ

[0104] The molar percentage of ethylene content was evaluated using the following equation:

[0105] E mole% = 100 * [PEP + PEE + EEE]

[0106] The weight percentage of ethylene content was evaluated using the following equation:

[0107] 100*E%mol*MWE

[0108] E%wt.=E%mol*MWE+P%mol*MWP

[0109] Where P mol% is the molar percentage of propylene content, and MWE and MWP are the molecular weights of ethylene and propylene, respectively.

[0110] Preparation of injection molded specimens: Obtain test specimens of 80 x 10 x 4 mm according to method ISO 1873-2:2007.

[0111] Flexural modulus: determined on injection molded test specimens according to method ISO 178:2019.

[0112] Tensile modulus: determined on an injection-molded test specimen according to method ISO 527-2.

[0113] Charpy impact test: Measured on injection-molded specimens according to ISO 179-1:2010.

[0114] Ezod impact test, measured according to ISO 180 / A using injection-molded specimens in accordance with ISO 1873-2.

[0115] Polydispersity index (PI): determined at 200°C using an RMS-800 parallel plate rheometer (sold by RHEOMETRICS, USA) operating at oscillation frequencies increasing from 0.1 radians / second to 100 radians / second. PI can be derived from the cross modulus using the following equation:

[0116] PI = 10⁵ / Gc

[0117] Where Gc is the cross modulus, which is defined as the value (in Pa) when G' = G”, where G' is the storage modulus and G” is the loss modulus.

[0118] Component A)

[0119] Preparation of solid catalyst components for component A)

[0120] 1000 mL of TiCl4 was introduced into a 2000 mL five-necked glass reactor equipped with a mechanical stirrer, jacket, and thermocouple, purged with nitrogen, and the reactor was cooled to -5 °C. While stirring, 60.0 g of microspheres MgCl2·1.7C2H5OH (prepared according to the method described in Example 1 of EP728769) with an average particle size of 58 μm was added at -5 °C. The temperature was raised to 40 °C, and a certain amount of diethyl 2,3-diisopropylsuccinate was added to make the Mg / succinate molar ratio 13. The temperature was raised to 100 °C and maintained at this value for 60 minutes. After this, stirring was stopped for 15 minutes and the solid was allowed to settle. The liquid was siphoned off. After siphoning, fresh TiCl4 and a certain amount of 9,9-bis(methoxymethyl)fluorene were added to make the Mg / diether molar ratio 26. The temperature was then raised to 110 °C with stirring and maintained for 30 minutes. The reactor was then cooled to 75°C and stirring was stopped for 15 minutes. After precipitation and siphoning, fresh TiCl4 was added. The temperature was then raised to 90°C and the suspension was stirred for 15 minutes. The temperature was then lowered to 75°C and stirring was stopped for 15 minutes. After precipitation and siphoning, the solid was washed six times with anhydrous hexane (6 x 1000 ml) at 60°C and once with hexane at 25°C. The solid was dried in a rotary evaporator.

[0121] Preparation of catalyst system

[0122] Before introducing it into the polymerization reactor, the above solid catalyst components are contacted with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) at a temperature of 15°C.

[0123] Prepolymerization

[0124] The catalyst system was then prepolymerized at 20°C by suspending it in liquid propylene for 9 minutes before being introduced into the polymerization reactor.

[0125] The polymerization operation is carried out continuously in the polymerization equipment, as described in EP 1 012 195.

[0126] The catalyst was fed into a polymerization apparatus comprising two interconnected cylindrical reactors (a riser and a downcomer). Rapid fluidization conditions were established in the riser by recirculating gas from a gas-solid separator. Hydrogen was used as a molecular weight regulator. The polymerization conditions are reported in Table 1. Component A is the component A used in Example 1 of WO2016 / 050461.

[0127] Table 1

[0128]

[0129]

[0130] C3 - =Propylene

[0131] The properties of component A are reported in Table 2.

[0132] Table 2

[0133] Component A MFR 5Kg / 230℃ g / 10 minutes 1.3 Polydispersity (PI) 6.0 Xylene-soluble substances at 25°C. ％ <2 Flexural modulus MPa 2050 tensile modulus MPa 1960 At 0°C, Ezod kJ / m2 4.3 Yield stress ％ 36 Elongation at break kJ / m2 28 Tm ℃ 164

[0134] Component B)

[0135] Component B1) is a commercial heterogeneous polymer obtained by sequential gas-phase polymerization, which was used as component B in Example 1 of WO2016 / 050461.

[0136] Component B2) is a commercial heterogeneous polymer obtained through sequential gas-phase polymerization. The characteristics of the polymer marketed by LyondellBasell under the trade name CA12A are reported in Table 3.

[0137] Table 3

[0138]

[0139]

[0140] *C2 = Ethylene-derived unit

[0141] Components A and B were blended. The properties of the resulting blend are reported in Table 4 for comparison with those of Comparative Example 2.

[0142] Table 4

[0143] blends 1 Comparative Example 2 Comparative Example 3 Components B2 B1 - Separation* weight% 6 5.2 0 MFR 5kg 230℃ g / 10 minutes 1.9 1.8 1.3 Charpy at 23°C kJ / m2 65.0 54 4.3 Charpy at 0°C kJ / m2 4.4 3.6 3.1 Flexural modulus MPa 2020 1930 2050 tensile modulus ％ 2070 2120 -

[0144] *The remainder is component A. Comparative Example 3 is component A only.

[0145] As can be clearly seen from Table 4, the impact characteristics of blend 1 are higher than those of the control blend 2 and component A alone, while the flexural modulus and tensile modulus remain basically unchanged.

[0146] 1.75% by weight of talc was added to blend 1 and comparative example 2. Water pressure resistance: Tested at 80°C and 4.20 MPa and at 95°C and 2.5 MPa according to ISO Method 1 167-1. Test results are reported in Table 5.

[0147] Table 5

[0148]

[0149]

[0150] As can be clearly seen from Table 5, the pressure resistance is improved by using the composition disclosed herein.

Claims

1. A) 85% to 99.0% by weight of a propylene homopolymer, said propylene homopolymer having: (i) Polydispersion index in the range of 5 to 10 (ii) 4.0% to 1.0% by weight of xylene soluble in xylene at 25°C; (iii) Melt flow rate in the range of 0.2 g / 10 min to 3.5 g / 10 min (230 °C / 5 kg..ISO 1133); B) A propylene-ethylene copolymer composition comprising 1.0% to 15.0% by weight, wherein the propylene-ethylene copolymer composition has the following characteristics: i) Fractions ranging from 35% to 61% by weight that are soluble in xylene at 25°C; ii) The melt flow rate (230°C / 2.16 kg..ISO1133) is in the range of 0.1 g / 10 min to 2.0 g / 10 min; iii) The intrinsic viscosity of the fraction that is soluble in xylene at 25°C, measured in naphthalene, ranges from 2.2 dl / g to 5.7 dl / g; iv) The content of ethylene-derived units ranges from 25.5% to 46.3% by weight; Component B of the propylene-ethylene copolymer composition comprises: b1) 24% to 54% by weight of propylene homopolymer, said propylene homopolymer having a melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) in the range of 2.0 g / 10 min to 19.0 g / 10 min; b2) 46% to 76% by weight of a propylene-ethylene copolymer, wherein the propylene-ethylene copolymer has an ethylene-derived unit content ranging from 40.7% to 77.5% by weight; The polyolefin composition wherein the polyolefin composition has a melt flow rate ranging from 0.4 g / 10 min to 4.0 g / 10 min (230 °C / 5 kg ISO 1133); the amount of A+B is 100% by weight and the amount of b1+b2 is 100% by weight.

2. The polyolefin composition according to claim 1, wherein component A) ranges from 90% to 98.5% by weight, and component B) ranges from 1.5% to 10.0% by weight.

3. The polyolefin composition according to claim 1, wherein in component B), b1) ranges from 29% to 49% by weight; and b2) ranges from 51% to 71% by weight.

4. The polyolefin composition according to claim 1, wherein the polyolefin composition has a melt flow rate in the range of 0.7 g / 10 min to 3.2 g / 10 min (230 °C / 5 kg. ISO 1133).

5. The polyolefin composition according to claim 1, wherein component B) has an ethylene-derived unit content ranging from 27.4% to 43.9% by weight.

6. The polyolefin composition according to claim 1, wherein the intrinsic viscosity of the fraction that is soluble in xylene at 25°C, as measured in naphthalene, is in the range of 2.4 dl / g to 5.2 dl / g.

7. The polyolefin composition according to claim 1, wherein the fraction in component B) that is soluble in xylene at 25°C ranges from 38% to 58% by weight.

8. The polyolefin composition according to claim 1, wherein in component B), component b1) has a melt flow rate MFR1 (230°C / 2.16 kg. ISO 1133) ranging from 4.0 g / 10 min to 17.0 g / 10 min.

9. The polyolefin composition according to claim 1, wherein in component B), component b2) has an ethylene-derived unit content ranging from 46.8% to 71.3% by weight.

10. The polyolefin composition according to claim 1, wherein component B) has an ethylene-derived unit content ranging from 33.4% to 49.9% by weight.

11. The polyolefin composition according to claim 1, wherein in component A), the soluble content in xylene at 25°C ranges from 3.0% by weight to 2.0% by weight.

12. The polyolefin composition according to claim 1, wherein component A) ranges from 93% to 98% by weight, and component B) ranges from 30.3% to 42.2% by weight.

13. The polyolefin composition according to claim 1, wherein component B) has a fraction ranging from 43% to 54% by weight that is soluble in xylene at 25°C.

14. The polyolefin composition according to claim 1, wherein component B) has the intrinsic viscosity of the fraction that is soluble in xylene at 25°C, measured in naphthalene, ranging from 2.7 dl / g to 4.7 dl / g.

15. A pipe comprising the polyolefin composition according to claim 1.

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