Pipes containing polypropylene compositions

Abstract

The present invention relates to a pipe comprising a polypropylene composition comprising a copolymer of propylene with comonomer units derived from 1-butene or 1-hexene and a copolymer of ethylene with comonomer units derived from 1-butene and / or 1-hexene, a method for manufacturing the pipe, and use of the polypropylene composition in the manufacture of the pipe.

Description

Technical Field

[0001] This invention relates to pipes comprising a polypropylene composition comprising a copolymer of propylene with comonomer units derived from 1-butene or 1-hexene and a copolymer of ethylene with comonomer units derived from 1-butene and / or 1-hexene. The invention also relates to a method of manufacturing the pipe and the use of the polypropylene composition in the manufacture of the pipe. Background Technology

[0002] Polypropylene materials are commonly used in various piping applications, such as fluid transport where the fluid is pressurized and / or heated during transport. In particular, polypropylene materials are suitable for piping and heating applications, such as in-house hot and cold water pressure piping and fittings, floor and wall heating systems, and radiator connections.

[0003] In this regard, propylene copolymers are particularly suitable for pressure piping applications in hot water and industrial pipelines because they have good impact resistance, stiffness, creep resistance, slow cracking properties, and long-term pressure resistance.

[0004] It is well known that improving impact resistance negatively impacts stiffness, and vice versa. However, for high-pressure pipelines, a good balance must be struck between impact resistance and stiffness to ensure sufficient pressure resistance against internal pressures. Furthermore, propylene copolymer materials are required to have good processability for pipe extrusion and injection molding. To increase the stiffness of propylene copolymer materials to the desired level, the comonomer content in the polymer can be reduced, but this negatively impacts the material's toughness. In particular, propylene copolymer grades used in hot and cold water applications often exhibit unsatisfactory impact resistance, especially under low-temperature conditions.

[0005] EP 3 567 061 A1 discloses a polypropylene composition comprising a single-point catalytic propylene-1-hexene random copolymer suitable for pressure piping applications. These pipes exhibit a good balance of performance in terms of stiffness and pressure resistance, but with relatively low impact strength.

[0006] Therefore, there is a need in the field to improve the impact properties of propylene copolymer materials without sacrificing stiffness and pressure resistance.

[0007] This invention achieves superior pipe performance based on the following findings: a polypropylene composition comprising a copolymer of propylene with comonomer units derived from 1-butene or 1-hexene, the copolymer being polymerized in a single-site catalyst system, and a copolymer of ethylene with comonomer units derived from 1-butene and / or 1-hexene. Summary of the Invention

[0008] This invention relates to pipes comprising a polypropylene composition, wherein the polypropylene composition comprises

[0009] (A) A copolymer of 70 to 95 wt.% of propylene and comonomer units derived from 1-butene or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0010] • Total comonomer content of 0.5 to 5.0 wt.%;

[0011] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 230 °C, from 0.10 to 2.0 g / 10 min; and

[0012] • The ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn), measured by gel permeation chromatography (GPC) from 2.5 to 6.0, according to ISO 16014-4:2003 and ASTM D 6474-99; and

[0013] (B) A copolymer of 5 to 30 wt.% ethylene with comonomer units derived from 1-butene and / or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0014] • Total comonomer content of 1.0 to 25.0 wt.%;

[0015] ·910.0 to 940.0 kg / m 3 The density measured according to ISO 1183; and

[0016] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 190 °C, from 0.05 to 3.0 g / 10 min;

[0017] The polypropylene composition, according to ISO 1133, has a melt flow rate (MFR2) of 0.1 to 1.0 g / 10 min, measured at a load of 2.16 kg and a temperature of 230 °C.

[0018] Furthermore, the present invention relates to a method for manufacturing the pipe described above or below, comprising the following steps:

[0019] a) In the presence of a single-point catalyst system, propylene and 1-butene or 1-hexene are polymerized in a multi-stage process to obtain a copolymer of propylene and comonomer units derived from 1-butene or 1-hexene (A).

[0020] b) Blending the propylene copolymer (A) and ethylene with a copolymer (B) derived from comonomer units of 1-butene and / or 1-hexene to obtain a polypropylene composition; and

[0021] c) Pipes are made from the polypropylene composition.

[0022] Furthermore, the present invention relates to the use of polypropylene compositions for the manufacture of pipes, said polypropylene compositions having a melt flow rate (MFR2) of 0.1-1.0 g / 10 min measured according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C, and containing

[0023] (A) A copolymer of 70 to 95 wt.% of propylene and comonomer units derived from 1-butene or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0024] • Total comonomer content of 0.5 to 5.0 wt.%;

[0025] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 230 °C, from 0.10 to 2.0 g / 10 min; and

[0026] • The ratio of weight-average molecular weight (Mw / Mn) to number-average molecular weight, measured by gel permeation chromatography (GPC) from 2.5 to 6.0, according to ISO 16014-4:2003 and ASTM D 6474-99; and

[0027] (B) A copolymer of 5 to 30 wt.% ethylene with comonomer units derived from 1-butene and / or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0028] • Total comonomer content of 1.0 to 25.0 wt.%;

[0029] ·910.0 to 940.0 kg / m 3 The density measured according to ISO 1183; and

[0030] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 190 °C, from 0.05 to 3.0 g / 10 min.

[0031] As can be seen from Charpy notched impact strength tests and pipe impact tests, the addition of 5 to 30 wt.% of the above-described or below-described ethylene copolymer (B) to the polypropylene composition can surprisingly improve the impact performance of the manufactured pipe without compromising the pressure resistance performance in the pressure test. Stiffness remains acceptable, as can be seen from the slightly lower but acceptable flexural modulus.

[0032] definition

[0033] The propylene random copolymer is a copolymer of propylene monomer units and comonomer units (in this invention, 1-butene or 1-hexene comonomer units), wherein the comonomer units are randomly distributed along the polypropylene chain. Therefore, based on the total amount of the propylene random copolymer, it contains at least 90 wt%, more preferably at least 95 wt%, and even more preferably at least 96 wt% of a fraction insoluble in xylene (xylene cold insoluble (XCI) fraction). Therefore, the propylene random copolymer does not contain an elastic polymer phase dispersed therein.

[0034] Propylene homopolymers are polymers primarily composed of propylene monomer units. Due to the presence of impurities, especially in commercial polymerization processes, propylene homopolymers may contain up to 0.1 mol-% monomer units, preferably up to 0.05 mol-% monomer units, and most preferably up to 0.01 mol-% monomer units.

[0035] "Ethylene homopolymer" refers to a polymer mainly composed of ethylene monomer units. Due to the requirements of large-scale polymerization, ethylene homopolymers may contain a small amount of comonomer units, typically less than 0.1 mol% of the ethylene homopolymer, preferably less than 0.05 mol% of the homopolymer, and most preferably less than 0.01 mol% of the homopolymer.

[0036] If a polymer is derived from an ethylene monomer unit and at least one α-olefin comonomer unit, the polymer is called an "ethylene copolymer". The α-olefin comonomer unit is selected from 1-butene and / or 1-hexene. A polymer having an ethylene monomer unit and a comonomer unit derived from 1-butene and 1-hexene is called an "ethylene terpolymer".

[0037] Ethylene polymers are typically classified according to density, such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). In the literature, densities prepared in the presence of a polymerization catalyst range from 910 to 945 kg / m³. 3 Polyethylene is usually classified as linear low-density polyethylene (LLDPE) or medium-density polyethylene (MDPE).

[0038] A polymer containing more than one fraction differing in at least one property (e.g., weight-average molecular weight or comonomer content) is called "multimodal". If a multimodal polymer contains two different fractions, it is called "bimodal", and correspondingly, if it contains three different fractions, it is called "trimodal". The shape of the molecular weight distribution curve of the multimodal polymer (i.e., the shape of the graph of the polymer weight fractions as a function of their molecular weights) will show more than two maximum values ​​depending on the modality, or at least be significantly wider than the curve for a single fraction.

[0039] In contrast to "multimodal", unimodal polymers show only one maximum value in the function graph of polymer weight fraction and molecular weight, and the comonomers are uniformly distributed.

[0040] In the following text, unless otherwise stated, the content is expressed as a weight percentage (wt.-%). Detailed Implementation

[0041] In a first aspect, the present invention relates to a pipe comprising a polypropylene composition, wherein the polypropylene composition comprises

[0042] (A) A copolymer of 70 to 95 wt.% of propylene and comonomer units derived from 1-butene or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0043] • Total comonomer content of 0.5 to 5.0 wt.%;

[0044] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 230 °C, from 0.10 to 2.0 g / 10 min; and

[0045] • The ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn), measured by gel permeation chromatography (GPC) from 2.5 to 6.0, according to ISO 16014-4:2003 and ASTM D 6474-99; and

[0046] (B) A copolymer of 5 to 30 wt.% ethylene with comonomer units derived from 1-butene and / or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0047] • Total comonomer content of 1.0 to 25.0 wt.%;

[0048] ·910.0 to 940.0 kg / m 3 The density measured according to ISO 1183; and

[0049] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 190 °C, from 0.05 to 3.0 g / 10 min;

[0050] The melt flow rate (MFR2) of the polypropylene composition, measured according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C, is 0.1 to 1.0 g / 10 min.

[0051] The pipeline has achieved an improved balance in terms of stiffness, impact resistance, and pressure resistance.

[0052] According to ISO 1167-1 and ISO 1167-2, the pipe pressure test stability of the pipeline, measured at a temperature of 95°C and a circumferential stress of 4.6 MPa, is preferably at least 5000 hours, and more preferably at least 5750 hours.

[0053] The upper limit is usually no more than 15,000 hours, preferably no more than 12,500 hours.

[0054] Furthermore, according to ISO 1167-1 and ISO 1167-2, the pipe pressure test stability of the pipeline, measured under conditions of 20°C and circumferential stress of 16 MPa, is preferably at least 5 hours, and more preferably at least 10 hours.

[0055] Furthermore, according to ISO 9854-2, in a pipe impact test at 0°C, the pipe preferably does not break.

[0056] Therefore, the pipe is qualified as a pressure pipe, preferably a pressure pipe for hot and cold water.

[0057] The content of the polypropylene composition in the pipe is preferably 90 to 100 wt.-%, more preferably 95 to 100 wt.-%, based on the total weight of the pipe. In a preferred embodiment, the pipe is composed of a polypropylene composition.

[0058] The polypropylene composition comprises a propylene copolymer (A) and an ethylene copolymer (B).

[0059] Furthermore, the polypropylene composition may contain other polymeric components different from the propylene copolymer (A) and the ethylene copolymer (B). The content of these other polymeric components is typically 0 to 10 wt.%, preferably 0 to 5 wt.%.

[0060] Preferably, the propylene copolymer (A) and ethylene copolymer (B) are the only polymer components of the polypropylene composition.

[0061] Furthermore, the polypropylene composition may contain non-polymer components, such as additives. These additives include antioxidants, processing stabilizers, UV stabilizers, pigments, fillers, antistatic additives, anti-clogging agents, nucleating agents, and acid scavengers.

[0062] Suitable antioxidants and stabilizers include, for example, 2,6-di-tert-butyl-p-cresol, tetra-[methylene-3-(3',5-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, octadecyl 3-3(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, dilauryl thiodipropionate, dioctadecyl thiodipropionate, tris(nonylphenyl) phosphate, distearate pentaerythritol diphosphite, and tetra(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphonate.

[0063] Some hindered phenols are sold under the trade names Irganox 1076 and Irganox 1010. Mixtures of commercially available antioxidants and processing stabilizers are also available, such as Irganox B225 sold by Ciba-Geigy.

[0064] Suitable acid scavengers are, for example, metal stearates, such as calcium stearate and zinc stearate. They are used in amounts commonly known in the art, typically from 500 ppm to 10,000 ppm, preferably from 500 to 5,000 ppm.

[0065] The polypropylene composition preferably has a polymer fraction of 4 to 25 wt.-%, more preferably 6 to 20 wt.-%, and even more preferably 8 to 15 wt.-%, which is a polymer fraction eluted at a temperature of 31 to 80°C, excluding the sweep fraction, and with a logM between 4.5 and 6.0, as determined by cross fractionation chromatography (CFC).

[0066] Furthermore, the profile of the polypropylene composition in the temperature elution fractionation (TREF) elution profile (obtained from cross fractionation chromatography (CFC)) contains two peaks, wherein the first peak Tp(1) preferably elutes between 45 and 90 °C, more preferably between 50 and 80 °C, and even more preferably between 55 and 70 °C, and the second peak Tp(2) preferably elutes between 85 and 100 °C, more preferably between 87 and 99 °C, and even more preferably between 90 and 98 °C.

[0067] The xylene cold solubles (XCS) content of the polypropylene composition, as determined according to ISO 16152, is preferably 1.0 to 3.5 wt.-, more preferably 1.2 to 3.2 wt.-, and even more preferably 1.5 to 3.0 wt.-.

[0068] Furthermore, the first melting temperature Tm1 of the polypropylene composition, as measured according to ISO 11357 / Part 3, is preferably 135 to 145°C, more preferably 137 to 142°C.

[0069] Furthermore, the second melting temperature Tm2 of the polypropylene composition, as measured according to ISO 11357 / Part 3, is preferably 115 to 130°C, more preferably 117 to 125°C.

[0070] Tm1 is usually higher than Tm2.

[0071] Furthermore, the crystallization temperature Tc of the polypropylene composition, as measured according to ISO 11357 / Part 3, is preferably 100 to 110°C, more preferably 102 to 107°C.

[0072] Furthermore, the first enthalpy of fusion Hm1 of the polypropylene composition, as measured according to ISO 11357 / Part 3, is preferably 30 to 45 J / g, more preferably 32 to 42 J / g.

[0073] Furthermore, the second enthalpy of melting Hm2 of the polypropylene composition, as measured according to ISO 11357 / Part 3, is preferably 35 to 50 J / g, more preferably 37 to 47 J / g.

[0074] Hm1 is usually lower than Hm2.

[0075] The polypropylene composition exhibits high impact strength at an acceptable stiffness.

[0076] According to ISO 178, the flexural modulus of the polypropylene composition is preferably 700 to 1000 MPa, more preferably 800 to 950 MPa, and even more preferably 850 to 925 MPa, as determined by injection molding specimens prepared according to EN ISO 1872-2.

[0077] Furthermore, the Charpy notched impact strength of the polypropylene composition at 23°C is preferably 7.5 to 15.0 kJ / m. 2 More preferably, it is 8.5 to 14.0 kJ / m 2 More preferably, it is 9.5 to 13.0 kJ / m 2 .

[0078] Furthermore, the Charpy notched impact strength of the polypropylene composition at 0°C is preferably 2.5 to 5.0 kJ / m. 2 More preferably 3.0 to 4.5 kJ / m 2 More preferably 3.0 to 4.0 kJ / m 2 .

[0079] Furthermore, the Charpy notched impact strength of the polypropylene composition at -20°C is preferably 1.5 to 4.0 kJ / m. 2 More preferably, it is 1.7 to 3.5 kJ / m 2 More preferably, it is 1.8 to 3.0 kJ / m 2 .

[0080] Charpy notched impact strength at 23°C, 0°C and -20°C was determined according to ISO 179 1eA on injection-molded specimens prepared according to EN ISO1872-2.

[0081] Based on the total weight of the polypropylene composition, the polypropylene composition contains 70 to 95 wt.% of propylene copolymer (A), preferably 75 to 93 wt.%, more preferably 80 to 90 wt.%.

[0082] The propylene copolymer (A) is a copolymer of propylene and comonomer units derived from 1-butene or 1-hexene. Preferably, the propylene copolymer (A) is a copolymer of propylene and comonomer units derived from 1-hexene.

[0083] "Copolymer of propylene and comonomer units derived from 1-butene" means that the propylene copolymer (A) contains only units derived from propylene and 1-butene.

[0084] "Copolymer of propylene and comonomer units derived from 1-hexene" means that the propylene copolymer (A) contains only units derived from propylene and 1-hexene.

[0085] The total monomer content (i.e., the content of monomer units derived from 1-butene or 1-hexene) of the propylene copolymer (A) is 0.5 to 5.0 wt.-, more preferably 1.0 to 4.0 wt.-, and even more preferably 2.0 to 3.0 wt.-, based on the total weight of the propylene copolymer (A).

[0086] The comonomer units are preferably randomly distributed in the polymer chain of the propylene copolymer (A). Therefore, the propylene copolymer (A) is preferably a random copolymer of propylene.

[0087] Furthermore, the melt flow rate (MFR2) of the propylene copolymer (A), measured according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C, is 0.10 to 2.0 g / 10 min, preferably 0.15 to 1.5 g / 10 min, and more preferably 0.20 to 1.0 g / 10 min.

[0088] Furthermore, the ratio of weight-average molecular weight (Mw / Mn) of the propylene copolymer (A) as determined by gel permeation chromatography (GPC) according to ISO 16014-4:2003 and ASTM D 6474-99 is 2.5 to 6.0, preferably 3.0 to 5.5, and even more preferably 3.5 to 5.0.

[0089] The xylene cold solubles (XCS) content of the propylene copolymer (A), as measured according to ISO 16152, is preferably 0.2 to 2.5 wt.-, more preferably 0.5 to 2.3 wt.-.

[0090] The melting temperature Tm of the propylene copolymer (A), as measured according to ISO 11357 / Part 3, is preferably 135 to 145 °C.

[0091] Furthermore, the crystallization temperature Tc of the propylene copolymer (A), as measured according to ISO 11357 / Part 3, is preferably 100 to 105°C.

[0092] Furthermore, the enthalpy of fusion Hm of the propylene copolymer (A) as measured according to ISO 11357 / Part 3 is preferably 70 to 80 J / g.

[0093] The propylene copolymer (A) can be obtained by polymerization in the presence of a single-point catalyst system.

[0094] The catalyst system preferably contains

[0095] (i) Catalysts having the following structure:

[0096]

[0097] In the formula,

[0098] M represents zirconium or hafnium;

[0099] Each X is an independent σ-donor ligand.

[0100] L is the formula -(ER) 10 2) y - the bridge foundation;

[0101] y is 1 or 2;

[0102] E is either C or Si;

[0103] Each R 10 Independently for C1-C 20 Hydrocarbon group, tri(C1-C) 20 Alkyl)silyl, C6-C 20 Aryl, C7-C 20 Aryl or C7-C 20Alkyl aryl, or L is an alkylene group, such as methylene or ethylene;

[0104] R 1 They are either independently the same or different from each other, and are CH2-R 11 Group, wherein R 11 It is H or a straight-chain or branched C1-C6 alkyl, C3-C8 cycloalkyl, C6-C 10 Aryl;

[0105] R 3 R 4 and R 5 Each is independently identical or different from the others, and is an H or a straight-chain or branched C1-C6 alkyl, C7-C 20 Aryl group, C7-C 20 Alkyl or C6-C 20 aryl, provided that there are at least four R groups different from H. 3 R 4 and R 5 Group, then R 3 R 4 and R 5 One or more of them are not tert-butyl;

[0106] R 7 and R 8 They are either independently the same or different from each other, and are H, CH2-R 12 Group, wherein R 12 It is H or a straight-chain or branched C1-C6 alkyl group, SiR 13 3. GeR 13 3. OR 13 SR 13 NR 13 2,

[0107] Among them, R 13 It is a straight-chain or branched C1-C6 alkyl, C7-C 20 Alkyl and C7-C 20 Aryl or C6-C 20 Aryl, R 9 Each is independently identical or different from the others, and is an H or a straight-chain or branched C1-C6 alkyl group; and

[0108] R 2 and R 6 All are H; and

[0109] (ii) A cocatalyst system containing an aluminoxane cocatalyst.

[0110] It should be emphasized that in some cases, the use of this co-catalyst system may not be necessary.

[0111] The catalyst system can be used in a non-supported form or a solid form. The catalyst system of the present invention can be used as a homogeneous catalyst system or a heterogeneous catalyst system.

[0112] The solid catalyst system is preferably a solid particulate catalyst system, which can be supported on an external support material (such as silica or alumina), or in a particularly preferred embodiment, no external support is required, but it is still in solid form. For example, a solid catalyst system can be obtained by the following methods, wherein...

[0113] (a) Forming a liquid / liquid emulsion system comprising a solution of catalyst components (i) and (ii) dispersed in a solvent, forming dispersed droplets; and

[0114] (b) By solidifying the dispersed droplets to form solid particles.

[0115] The specific complexes of this invention include:

[0116] Racemic-trans-dimethylsilanediyl[2-methyl-4-(4-tert-butylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(4-tert-butylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0117] Racemic-trans-dimethylsilanediyl[2-isobutyl-4-(4-tert-butylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(4-tert-butylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0118] Racemic-trans-dimethylsilanediyl[2-neopentyl-4-(4-tert-butylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(4-tert-butylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0119] Racemic-trans-dimethylsilanediyl[2-benzyl-4-(4-tert-butylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(4-tert-butylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0120] Racemic-trans-dimethylsilanediyl[2-cyclohexylmethyl-4-(4-tert-butylphenyl)-5,6,7-tri-s-indan-1-yl][2-methyl-4-(4-tert-butylphenyl)-5-methoxy-6-tert-butylindanylzirconium dichloride or dimethylzirconium,

[0121] Racemic e-trans-dimethylsilanediyl[2-methyl-4-(3,5-dimethylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0122] Racemic-trans-dimethylsilanediyl[2-isobutyl-4-(3,5-dimethylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0123] Racemic-trans-dimethylsilanediyl[2-neopentyl-4-(3,5-dimethylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium,

[0124] Racemic-trans-dimethylsilanediyl[2-benzyl-4-(3,5-dimethylphenyl)-5,6,7-trihydro-s-inden-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylindenylzirconium dichloride or dimethylzirconium, and

[0125] Racemic-trans-dimethylsilanediyl[2-cyclohexylmethyl-4-(3,5-dimethylphenyl)-5,6,7-trihydro-s-indene-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylindene dizirconia or dimethylzirconia.

[0126] The aforementioned catalysts have been described in documents such as WO2015 / 011135, which are incorporated herein by reference. A particularly preferred catalyst is catalyst No. 3 of WO2015 / 011135. Methods for preparing metallocenes have been described in WO2013 / 007650, which are incorporated herein by reference. A particularly preferred method for preparing the catalyst complex is E2 of WO2013 / 007650.

[0127] To avoid ambiguity, the above narrow definition of substituents may be combined with the broad or narrow definitions of any other substituents.

[0128] In the above disclosure, when a narrow definition of a substituent is given, that narrow definition is considered to be disclosed together with all broad and narrow definitions of other substituents in this application.

[0129] The ligands required to form the complexes and catalyst / catalyst systems can be synthesized by any method, and skilled organic chemists can design various synthetic schemes to produce the necessary ligand materials. For example, WO2007 / 116034 discloses the necessary chemical methods. Synthetic schemes can also generally be found in WO2002 / 02576, WO2011 / 135004, WO2012 / 084961, WO2012 / 001052, WO2011 / 076780, and WO2015 / 158790. The examples section also provides ample guidance for those skilled in the art.

[0130] As mentioned above, a cocatalyst system is not always required. However, when used, the cocatalyst system contains an aluminoxane cocatalyst.

[0131] The aluminum oxane co-catalyst can be one of formula (X):

[0132]

[0133] In the formula, n is usually between 6 and 20, and R has the following meanings.

[0134] Aluminoxanes are formed through the partial hydrolysis of organoaluminum compounds, such as those with the general formulas AlR3, AlR2Y, and Al2R3Y3, where R can be, for example, C1-C2. 10 Alkyl groups, preferably C1-C5 alkyl groups, or C3-C5 alkyl groups. 10 cycloalkyl, C7-C 12 -Aryl or alkylaryl and / or phenyl or naphthyl, wherein Y can be hydrogen, halogen, preferably chlorine or bromine, or C1-C 10 Alkoxy, preferably methoxy or ethoxy. The resulting oxyaluminoxane is usually not a pure compound, but a mixture of oligomers of formula (X).

[0135] The preferred aluminoxane is methylaluminoxane (MAO). Since the aluminoxanes used as cocatalysts in this invention are not pure compounds due to their preparation method, the molar concentrations of the aluminoxane solutions mentioned below are based on their aluminum content.

[0136] The molar ratio of Al to metal ions in aluminoxane can be from 1:1 to 2000:1 mol / mol, preferably from 10:1 to 1000:1, and more preferably from 50:1 to 500:1 mol / mol.

[0137] The cocatalyst system may additionally include a boron-containing cocatalyst.

[0138] The relevant boron-based cocatalysts include those of formula (Z).

[0139] BY3(Z)

[0140] In the formula, Y is independently the same or different, and is a hydrogen atom, an alkyl group of 1 to 20 carbon atoms, an aryl group of 6 to 15 carbon atoms, an alkylaryl group, an aralkyl group, a haloalkyl group, or a haloaryl group, wherein each alkyl group contains 1 to 10 carbon atoms, each aryl group contains 6 to 20 carbon atoms, or fluorine, chlorine, bromine, or iodine. Preferred embodiments of Y are methyl, propyl, isopropyl, isobutyl, or trifluoromethyl, unsaturated groups such as aryl or haloaryl groups such as phenyl, tolyl, benzyl, p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl, and 3,5-di(trifluoromethyl)phenyl. Preferred options are trifluoroborane, triphenylborane, tri(4-fluorophenyl)borane, tri(3,5-difluorophenyl)borane, tri(4-fluoromethylphenyl)borane, tri(2,4,6-trifluorophenyl)borane, tri(pentafluorophenyl)borane, tri(tolyl)borane, tri(3,5-dimethylphenyl)borane, tri(3,5-difluorophenyl)borane and / or tri(3,4,5-trifluorophenyl)borane.

[0141] Tris(pentafluorophenyl)borane is particularly preferred.

[0142] Borates, i.e., compounds containing borate 3+ ions, can be used. This ionic cocatalyst preferably contains a noncoordinate anion, such as tetra(pentafluorophenyl)borate and tetraphenylborate. Suitable counterions are protonated amines or aniline derivatives, such as methylammonium, aniline, dimethylammonium, diethylamine, N-methylaniline, diphenylamine, N,N-dimethylaniline, trimethylammonium, triethylammonium, tri-n-butylammonium, methyldiphenylammonium, pyridine, p-bromo-N,N-dimethylaniline, or p-nitro-N,N-dimethylaniline.

[0143] Preferred ionic compounds that can be used in this invention include: triethylammonium tetra(phenyl)borate, tributylammonium tetra(phenyl)borate, trimethylammonium tetra(tolyl)borate, tributylammonium tetra(tolyl)borate, tributylammonium tetra(pentafluorophenyl)borate, tripropylammonium tetra(dimethylphenyl)borate, tributylammonium tetra(trifluoromethylphenyl)borate, tributylammonium tetra(4-fluorophenyl)borate, N,N-dimethylcyclohexylammonium tetra(pentafluorophenyl)borate, N,N-dimethylbenzylammonium tetra(pentafluorophenyl)borate, and N,N-dimethylaniline tetra(phenyl)borate. N,N-Diethylaniline tetra(phenyl)borate, N,N-Dimethylaniline tetra(pentafluorophenyl)borate, N,N-di(propyl)ammonium tetra(pentafluorophenyl)borate, di(cyclohexyl)ammonium tetra(pentafluorophenyl)borate, triphenylphosphonium tetra(phenyl)borate, triethylphosphonium tetra(phenyl)borate, diphenylphosphonium tetra(phenyl)borate, tri(methylphenyl)phosphonium tetra(phenyl)borate, tri(dimethylphenyl)phosphonium tetra(phenyl)borate, triphenylcarbamonium tetra(pentafluorophenyl)borate, or ferrocene tetra(pentafluorophenyl)borate.

[0144] Preferred are triphenylcarbium tetra(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetra(pentafluorophenyl)borate, or N,N-dimethylbenzylammonium tetra(pentafluorophenyl)borate.

[0145] The appropriate amount of co-catalyst is well known to technicians.

[0146] The molar ratio of boron to metallocene ions can be from 0.5:1 to 10:1 mol / mol, preferably from 1:1 to 10:1, and particularly preferably from 1:1 to 5:1 mol / mol.

[0147] The catalyst can be used in supported or unsupported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina, or zirconium oxide, or a mixed oxide, such as silica-alumina, particularly silica, alumina, or silica-alumina. Silica support is preferred. The procedures required for supporting metallocene catalysts are known to those skilled in the art.

[0148] The support is particularly preferably a porous material, allowing the composite to be loaded into the pores of the support, for example using methods similar to those described in WO94 / 14856 (Mobil), WO95 / 12622 (Borealis), and WO2006 / 097497. The particle size is not strictly defined, but is preferably in the range of 5 to 200 μm, more preferably 20 to 80 μm. The use of these supports is standard practice in the art.

[0149] In an alternative embodiment, no support is used. This catalyst system can be prepared in solution, for example in an aromatic solvent (e.g., toluene), by contacting a metallocene (solid or in solution) with a co-catalyst (e.g., methylaluminoxane previously dissolved in an aromatic solvent), or by sequentially adding the dissolved catalyst components to a polymerization medium.

[0150] In a particularly preferred embodiment, no external support is used, but the catalyst still exists in the form of solid particles. Therefore, external support materials such as inert organic or inorganic supports (e.g., silica as described above) are not used.

[0151] To provide the catalyst in solid form without the use of an external support, a liquid / liquid emulsion system is preferably used. This method involves forming dispersed catalyst components (i) and (ii) in a solvent and solidifying the dispersed droplets to form solid particles.

[0152] Specifically, the method includes preparing a solution of one or more catalyst components; dispersing the solution in a solvent to form an emulsion, wherein the one or more catalyst components are present in droplets of the dispersed phase; immobilizing the catalyst components in the dispersed droplets in the absence of an external particulate porous support to form solid particles containing the catalyst, and optionally recovering the particles.

[0153] This method enables the production of active catalyst particles with improved morphology, such as predetermined spherical shapes, surface properties, and particle sizes, without the use of any additional external porous support materials, such as inorganic oxides (e.g., silica). The term "preparation of a solution of more than one catalyst component" means that the catalyst-forming compound can be mixed with a solution dispersed in an immiscible solvent, or that at least two separate catalyst solutions can be prepared for each portion of the catalyst-forming compound and then sequentially dispersed in a solvent.

[0154] In a preferred method of forming the catalyst, at least two separate solutions may be prepared for each or part of the catalyst, and then dispersed sequentially in an immiscible solvent.

[0155] More preferably, the complex solution containing the transition metal compound and the co-catalyst is mixed with a solvent to form an emulsion, wherein the inert solvent forms a continuous liquid phase, and the solution containing the catalyst component forms a dispersed phase (discontinuous phase) in the form of dispersed droplets. The droplets are then solidified to form solid catalyst particles, which are separated from the liquid and optionally washed and / or dried. The solvent forming the continuous phase is immiscible with the catalyst solution at least under the conditions (e.g., temperature) of the dispersion step.

[0156] The term "immiscible with catalyst solution" means that the solvent (continuous phase) and the dispersed phase solution are completely or partially immiscible, i.e., not completely immiscible.

[0157] Preferably, the solvent is inert relative to the compound in the catalyst system to be prepared. WO03 / 051934 fully discloses the necessary methods.

[0158] The inert solvent must be chemically inert, at least under the conditions (e.g., temperature) of the dispersion step. Preferably, the solvent of the continuous phase does not contain any significant amount of catalyst-forming compounds dissolved therein. Thus, solid particles of the catalyst are formed in droplets from the compounds in the dispersed phase (i.e., provided to the emulsion as a solution dispersed in the continuous phase).

[0159] "Immobilization" and "solidification" are used interchangeably herein for the same purpose: to form free-flowing solid catalyst particles without an external porous particulate support (such as silica). Therefore, solidification occurs within the droplet. This step can be achieved by various methods disclosed in WO03 / 051934. Preferably, solidification is caused by an external stimulus to the emulsion system, such as a temperature change. Thus, in this step, the catalyst component remains "fixed" within the formed solid particles. More than one catalyst component may also participate in the solidification / immobilization reaction.

[0160] Therefore, it is possible to obtain solid particles with uniform composition and a predetermined particle size range.

[0161] Furthermore, the particle size of the catalyst particles of the present invention can be controlled by the size of the droplets in the solution, thereby obtaining spherical particles with uniform particle size distribution.

[0162] This method is also industrially advantageous because it allows for the preparation of solid particles in a one-pot process. Continuous or semi-continuous processes can also be used to prepare the catalyst.

[0163] Based on the total weight of the polypropylene composition, the polypropylene composition contains 5 to 30 wt.% of ethylene copolymer (B), preferably 7 to 25 wt.%, more preferably 10 to 20 wt.%.

[0164] The ethylene copolymer (B) is a copolymer of ethylene with comonomer units derived from 1-butene and / or 1-hexene. Preferably, the ethylene copolymer (B) is a terpolymer of ethylene with comonomer units derived from 1-butene and 1-hexene.

[0165] The term "polymer of ethylene and comonomer units derived from 1-butene" means that the ethylene copolymer (B) contains only units derived from ethylene and 1-butene.

[0166] The term "copolymer of ethylene and comonomer units derived from 1-hexene" means that the ethylene copolymer (B) contains only units derived from ethylene and 1-hexene.

[0167] The term "ethylene terpolymer of ethylene with comonomer units derived from 1-butene and 1-hexene" means that the ethylene copolymer (B) contains only units derived from ethylene, 1-butene and 1-hexene.

[0168] The total comonomer content of the ethylene copolymer (B) (i.e., the content of comonomer units derived from 1-butene and / or 1-hexene) is 1.0 to 25.0 wt.-, preferably 1.5 to 22.5 wt.-, and even more preferably 2.0 to 20.0 wt.-.

[0169] Based on the total weight of the ethylene copolymer (B), the 1-butene content of the ethylene copolymer (B) is preferably 0.1 to 5.0 wt.-%, more preferably 0.2 to 3.5 wt.-%, and even more preferably 0.3 to 2.0 wt.-%.

[0170] Based on the total weight of the ethylene copolymer (B), the 1-hexene content of the ethylene copolymer (B) is preferably 5.0 to 25.0 wt.-, more preferably 6.0 to 22.5 wt.-, and even more preferably 7.5 to 20.0 wt.-.

[0171] The comonomer distribution of the ethylene copolymer (B) can be monomodal. This means that comonomer units derived from 1-butene and / or 1-hexene are uniformly distributed in the ethylene copolymer (B).

[0172] In terms of comonomer distribution, ethylene copolymers (B) can be multimodal.

[0173] This means that the ethylene copolymer (B) contains different components.

[0174] When used as a copolymer of ethylene and a comonomer unit derived from 1-butene or 1-hexene, in one embodiment, the ethylene copolymer (B) may comprise an ethylene homopolymer component and a copolymer of ethylene and a 1-butene or 1-hexene component.

[0175] When used as a copolymer of ethylene and comonomer units derived from 1-butene or 1-hexene, in another embodiment, the ethylene copolymer (B) may comprise two copolymers of ethylene and 1-butene or 1-hexene components with different amounts of the two comonomers.

[0176] When used as a terpolymer of ethylene and comonomer units derived from 1-butene and 1-hexene, in one embodiment, the ethylene copolymer (B) may comprise an ethylene homopolymer component, an ethylene-1-butene copolymer component, and an ethylene-1-hexene copolymer component.

[0177] In another embodiment, when used as a terpolymer of ethylene and comonomer units derived from 1-butene and 1-hexene, the ethylene copolymer (B) may comprise a terpolymer of ethylene homopolymer components and ethylene, 1-butene, and 1-hexene components.

[0178] In another embodiment, when the ethylene copolymer (B) is a terpolymer of ethylene and comonomer units derived from 1-butene and 1-hexene, the ethylene copolymer (B) may comprise a copolymer of ethylene and a 1-butene component and a copolymer of ethylene and a 1-hexene component.

[0179] In a preferred embodiment, the ethylene copolymer (B) is a terpolymer of ethylene and comonomer units selected from 1-butene and 1-hexene, wherein the 1-butene content, based on the total weight of the ethylene copolymer (B), is 0.1-5.0 wt.-%, preferably 0.2-3.5 wt.-%, and even more preferably 0.3-2.0 wt.-%. The 1-hexene content is 5.0-24.9 wt.-%, more preferably 6.0-22.3 wt.-%, and even more preferably 7.5-19.7 wt.-%.

[0180] The density of the ethylene copolymer (B), as measured according to ISO 1183, is 910.0 to 940.0 kg / m³. 3 Preferably, it is between 912.0 and 938.0 kg / m³. 3 More preferably, it is 0.15.0 to 935 kg / m 3 .

[0181] The ethylene copolymer (B) is preferably linear low-density polyethylene (LLDPE).

[0182] The melt flow rate (MFR2) of the ethylene copolymer (B), as measured according to ISO 1133 at a load of 2.16 kg and a temperature of 190 °C, is 0.05 to 3.0 g / 10 min, preferably 0.10 to 2.5 g / 10 min, and more preferably 0.50 to 2.0 g / 10 min.

[0183] The intrinsic viscosity iV of the ethylene copolymer (B), as measured according to DIN ISO 1628 / 1 (in decahydronaphthalene at 135°C) in October 1999, is preferably 1.5 to 2.5 dl / g, more preferably 1.7 to 2.2 dl / g.

[0184] Furthermore, the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) of the ethylene copolymer (B), as determined by gel permeation chromatography (GPC) according to ISO 16014-4:2003 and ASTM D 6474-99, is preferably 2.0 to 5.0, more preferably 2.5 to 4.5, and even more preferably 3.0 to 4.0.

[0185] The ethylene copolymer (B) is preferably obtained by polymerization in the presence of a single-point catalyst system. The single-point catalyst system preferably comprises a catalytically active metallocene compound or complex combined with a cocatalyst. The metallocene compound or complex is also referred to herein as an organometallic compound (C).

[0186] Organometallic compounds (C) contain transition metals (M) of elements in groups 3 to 10 of the periodic table (IUPAC 2007), or of the actinides or lanthanides.

[0187] The term "organometallic compound (C)" in this invention includes metallocene compounds of any transition metal that have at least one organic (coordinating) ligand and exhibit catalytic activity, alone or in combination with a cocatalyst. Transition metal compounds are well known in the art and preferably include metal compounds of groups 3 to 10, such as groups 3 to 7 or 3 to 6, such as groups 4 to 6 of the periodic table (IUPAC 2007), as well as lanthanides or actinides.

[0188] In one embodiment, the organometallic compound (C) has the following formula (I):

[0189] (L)mRnMXq(I)

[0190] In the formula,

[0191] “M” represents transition metals (M) in groups 3 to 10 of the periodic table (IUPAC 2007).

[0192] Each "X" is independently a monoanion ligand, such as an o-ligand.

[0193] Each "L" is an independent organic ligand that coordinates with a transition metal "M".

[0194] “R” represents the bridging group that connects the organic ligand (L).

[0195] "m" can be 1, 2, or 3, with 2 being the preferred value.

[0196] "n" can be 0, 1, or 2, with 1 being the preferred value.

[0197] "q" can be 1, 2, or 3, with 2 being the preferred value.

[0198] m+q equals the valence of the transition metal (M).

[0199] "M" is preferably selected from zirconium (Zr), hafnium (Hf) or titanium (Ti), and more preferably from zirconium (Zr) and hafnium (Hf).

[0200] "X" is preferably a halogen, and most preferably Cl.

[0201] Most preferably, the organometallic compound (C) is a metallocene complex comprising a transition metal compound as defined above, which contains a cyclopentadienyl, indenyl, or fluorenyl ligand as a substituent "L". Further, the ligand "L" may have substituents, such as alkyl, aryl, aralkyl, alkylaryl, silyl, siloxy, alkoxy, or other heteroatom groups. Suitable metallocene catalysts are known in the art and are disclosed in WO-A-95 / 12622, WO-A-96 / 32423, WO-A-97 / 28170, WO-A-98 / 32776, WO-A-99 / 61489, WO-A-03 / 010208, WO-A-03 / 051934, WO-A-03 / 051514, WO-A-2004 / 085499, EP-A-1752462 and EP-A-1739103.

[0202] Most preferably, the metallocene catalyst (referring to the catalytically active metallocene complex as defined above) is used in conjunction with a co-catalyst (also called an activator). Suitable activators are metal alkyl compounds known in the art, especially alkylaluminum compounds. Particularly suitable activators for use with metallocene catalysts are alkylaluminoxanes, such as methylaluminoxane (MAO), tetraisobutylaluminoxane (TIBAO), or hexaisobutylaluminoxane (HIBAO).

[0203] method

[0204] On the other hand, the present invention relates to a method for manufacturing the above-described or below-described pipe, comprising the following steps:

[0205] a) In the presence of a single-point catalyst system, propylene and 1-butene or 1-hexene are polymerized in a multi-stage process to obtain a copolymer of propylene and comonomer units derived from 1-butene or 1-hexene (A).

[0206] b) Blending the propylene copolymer (A) with a copolymer (B) of ethylene and comonomer units derived from 1-butene and / or 1-hexene to obtain a polypropylene composition; and

[0207] c) Pipes are made from the polypropylene composition.

[0208] The propylene copolymer (A) is preferably polymerized under the above-described single-point catalyst system.

[0209] The propylene copolymer (A) is preferably polymerized in a multi-stage process, which is a sequential polymerization process having at least two polymerization reactors connected in series.

[0210] Multi-stage process optimization includes the following steps:

[0211] (i) A stream of propylene and 1-butene or 1-hexene (preferably 1-hexene) is introduced into the first reactor such that the ratio of the feed rate of 1-butene or 1-hexene (preferably 1-hexene) to the feed rate of propylene is 2.0 to 4.0 mol / kmol; a catalyst system stream is further introduced into the first reactor.

[0212] (ii) Extracting the product stream containing the first intermediate (PP1) from the first reactor

[0213] (iii) The first intermediate (PP1) is transferred to a second reactor, and further polymerized in the second reactor in the presence of hydrogen by further adding propylene, 1-butene, or 1-hexene (preferably 1-hexene), such that...

[0214] The ratio of hydrogen concentration to propylene concentration is in the range of 0.1 to 0.8 mol / kmol; and further...

[0215] The concentration of 1-butene or 1-hexene (preferably 1-hexene) is in the range of 3.0 to 6.0 mol / kmol relative to the concentration of propylene.

[0216] (iv) Producing a powder of propylene copolymer (A).

[0217] Regarding the overall process, the propylene composition is prepared in a continuous polymerization process comprising at least two polymerization zones operating under different conditions to prepare the propylene composition. The polymerization zones may operate under slurry, solution, or gas phase conditions, or a combination thereof. Suitable processes are disclosed in WO-A-98 / 58976, EP-A-887380, and WO-A-98 / 58977.

[0218] The catalyst can be transferred to the polymerization zone by any means known in the art. Thus, the catalyst can be suspended in a diluent and kept as a homogeneous slurry. Oils with a viscosity of 20 to 1500 mPa·s, as disclosed in WO-A-2006 / 063771, are particularly preferred as diluents. Alternatively, the catalyst can be mixed with a viscous mixture of grease and oil, and the resulting paste can be added to the polymerization zone. Furthermore, the catalyst can be allowed to settle, and a portion of the resulting catalyst slurry can be introduced into the polymerization zone in a manner disclosed, for example, in EP-A-428054.

[0219] Gas-phase polymerization can be carried out in fluidized bed reactors, fast fluidized bed reactors, or settling bed reactors, or any combination of these reactors. When using a combination of reactors, polymer is transferred from one polymerization reactor to another. Furthermore, some or all of the polymer from the polymerization stage can be returned to the previous polymerization stage.

[0220] In a preferred embodiment, prepolymerization is carried out continuously in liquid propylene via bulk slurry polymerization, i.e., the liquid phase mainly comprises propylene, with small amounts of other reactants and optional inert components dissolved therein. Prepolymerization is preferably carried out in a continuous stirred tank reactor or a circulating reactor.

[0221] The prepolymerization reaction is typically carried out at a temperature of 0 to 40°C, preferably 10 to 30°C, and more preferably 15 to 25°C.

[0222] The pressure in the prepolymerization reactor is not critical, but it must be high enough to keep the reaction mixture in the liquid phase. Therefore, the pressure can be 20 to 100 bar, for example, 30 to 70 bar.

[0223] The reaction conditions are well known in the art, for example, the reaction conditions disclosed in GB 1580635.

[0224] In the prepolymerization step, comonomers can also be added to the prepolymerization stage.

[0225] On average, the amount of prepolymer on the catalyst is preferably 10 to 1000 g per gram of solid catalyst component, more preferably 50 to 500 g per gram of solid catalyst component.

[0226] As those skilled in the art will know, catalyst particles recovered from a continuously stirred prepolymerization reactor do not all contain the same amount of prepolymer. Instead, each particle has its own characteristic amount, which depends on the residence time of the particle in the prepolymerization reactor. Since some particles reside in the reactor for relatively long times while others reside for relatively short times, the amount of prepolymer on different particles also varies, and some individual particles may contain amounts of prepolymer exceeding the aforementioned range. However, the average amount of prepolymer on the catalyst is preferably within the aforementioned range. The amount of prepolymer is known in the art, for example, as disclosed in GB 1580635.

[0227] Other components may also be added to the prepolymerization stage. Therefore, as is known in the art, hydrogen can be added to the prepolymerization stage to control the molecular weight of the prepolymer. Furthermore, as disclosed in WO-A-00 / 66640, antistatic additives can be used to prevent particles from adhering to each other or to the reactor wall.

[0228] Polymerization in the first polymerization zone can take place in a slurry. The polymer particles formed during polymerization are then suspended in a fluid hydrocarbon along with the fragmented and dispersed catalyst within the particles. The slurry is stirred to transfer the reactants from the fluid into the particles.

[0229] Slurry polymerization is preferably so-called bulk polymerization. "Bulk polymerization" refers to a method of polymerization in liquid monomers in the absence of substantially any inert diluent. However, as those skilled in the art will know, monomers used in commercial production are never pure, but always contain aliphatic hydrocarbons as impurities. For example, propylene monomers can contain up to 5% propane impurities. Because propylene is consumed in the reaction and also recycled back to the polymerization reaction from the reaction effluent, inert components tend to accumulate, and therefore the reaction medium can contain up to 40 wt% of compounds other than the monomer. However, it should be understood that this polymerization method is still within the scope of the "bulk polymerization" meaning defined above.

[0230] The temperature in slurry polymerization is typically 50 to 110°C, preferably 60 to 100°C, and particularly preferably 65 to 95°C. The pressure is 1 to 150 bar, preferably 10 to 100 bar. In some cases, polymerization is preferably carried out at a temperature higher than the critical temperature of the fluid mixture constituting the reaction phase and a pressure higher than the critical pressure of the fluid mixture. Such reaction conditions are commonly referred to as "supercritical conditions." "Supercritical fluid" is used to describe fluids or fluid mixtures whose temperature and pressure exceed critical temperature and pressure.

[0231] Slurry polymerization can be carried out in any known reactor for slurry polymerization. Such reactors include continuous stirred tank reactors and circulating reactors. Polymerization is particularly preferred in circulating reactors. In such reactors, the slurry is circulated at high speed along closed pipes using a circulating pump. Circulating reactors are well known in the art, and examples are given for example in US-A-4582816, US-A-3405109, US-A-3324093, EP-A-479186, and US-A-5391654.

[0232] The slurry can be extracted from the reactor continuously or intermittently. A preferred method for intermittent extraction is the use of a settling leg, in which the solids concentration of the slurry is increased before extracting a batch of concentrated slurry from the reactor. The use of a settling leg is disclosed in US-A-3374211, US-A-3242150, and EP-A-1310295. Continuous extraction is disclosed in EP-A-891990, EP-A-1415999, EP-A-1591460, and EP-A-1860125. As disclosed in EP-A-1860125 and EP-A-1591460, continuous extraction can be combined with a suitable concentration method.

[0233] Other components may also be introduced into the slurry polymerization stage, as is known in the art.

[0234] Process additives can also be introduced into the reactor to promote stable process operation.

[0235] When the slurry polymerization stage is followed by the gas-phase polymerization stage, it is preferable to directly introduce the slurry into the gas-phase polymerization zone, without a flash evaporation step between the two stages. EP-A-887379, EP-A-887380, EP-A-887381 and EP-A-991684 describe this direct feeding method.

[0236] The propylene copolymer (A) obtained from a multi-stage process can be extruded and granulated, and then blended with the ethylene copolymer (B) in granular form.

[0237] The propylene copolymer (A) obtained from the multi-stage process can also be blended with the ethylene copolymer (B) in powder form.

[0238] The ethylene copolymer (B) is preferably polymerized under the above-described single-point catalyst system.

[0239] The ethylene copolymer (B) can be prepared by any suitable polymerization method known in the art, which includes at least one polymerization stage, wherein polymerization is typically carried out in solution, slurry, bulk, or gas phase. Preferably, the ethylene copolymer (B) is prepared in a multi-stage polymerization process comprising at least two polymerization zones.

[0240] The first ethylene polymer component is preferably prepared in the first polymerization zone, and the second ethylene polymer component is preferably prepared in the second polymerization zone. The first and second polymerization zones can be connected in any order; that is, the first polymerization zone can precede the second polymerization zone, or the second polymerization zone can precede the first polymerization zone, or the polymerization zones can be connected in parallel. However, it is preferred to operate the polymerization zones in a cascade mode. The polymerization zones can be operated under slurry, solution, or gas phase conditions, or combinations thereof.

[0241] Suitable methods including cascaded slurry and gas-phase polymerization stages are disclosed in WO-A-92 / 12182 and WO-A-96 / 18662.

[0242] It is generally preferable to remove reactants from the polymer from the previous polymerization stage before introducing it into a subsequent polymerization stage. This is preferably done when transferring the polymer from one polymerization stage to another.

[0243] The catalyst can be transferred to the polymerization zone by any means known in the art. For example, the catalyst can be suspended in a diluent and kept as a homogeneous slurry, the catalyst can be mixed with a viscous mixture of grease and oil and the resulting paste can be fed into the polymerization zone, or the catalyst can be allowed to settle and a portion of the resulting catalyst slurry can be introduced into the polymerization zone.

[0244] The polymerization in the first polymerization zone is preferably carried out in a slurry. The polymer particles formed during polymerization are then suspended in a fluid hydrocarbon along with the catalyst, which is broken up and dispersed within the particles. The slurry is stirred to transfer the reactants from the fluid into the particles.

[0245] Polymerization is typically carried out in an inert diluent, usually a hydrocarbon diluent such as methane, ethane, propane, n-butane, isobutane, pentane, hexane, heptane, octane, or mixtures thereof. Preferably, the diluent is a low-boiling-point hydrocarbon or a mixture of these hydrocarbons having 1 to 4 carbon atoms, with propane being a preferred diluent.

[0246] The ethylene content in the fluid phase of the slurry can be from 2 to 50 mol%, preferably from about 2 to about 20 mol%, and particularly preferably from about 3 to about 12 mol%.

[0247] The temperature during slurry polymerization is typically 50 to 115°C, preferably 60 to 110°C, and particularly preferably 70 to 100°C. The pressure is 1 to 150 bar, preferably 10 to 100 bar.

[0248] Slurry polymerization can be carried out in any known reactor used for slurry polymerization.

[0249] Such reactors include continuous stirred tank reactors and circulating reactors. Polymerization is particularly preferred in circulating reactors. In such reactors, the slurry is circulated at high speed along closed pipes using a circulating pump. Circulating reactors are well known in the art, and examples are given for example in US-A-4582816, US-A-3405109, US-A-3324093, EP-A-479186, and US-A-5391654.

[0250] Sometimes, it is advantageous to carry out slurry polymerization above the critical temperature and pressure of the fluid mixture. Such an operation is described in US-A-5391654. In this operation, the temperature is typically 85 to 110°C, preferably 90 to 105°C, and the pressure is 30 to 150 bar, preferably 50 to 100 bar.

[0251] The slurry can be extracted from the reactor continuously or intermittently. Intermittent extraction is preferred when using a settling rod, where the slurry can be concentrated before a batch of concentrated slurry is extracted from the reactor. As disclosed in EP-A-1310295 and EP-A-1591460, combining continuous extraction with a suitable concentration method is advantageous.

[0252] As is known in the art, hydrogen can be added to the reactor to control the molecular weight of the polymer. Additionally, 1-butene and / or 1-hexene can be added to the reactor, for example, to control the density of the polymer product. The actual amounts of these hydrogen and 1-butene and / or 1-hexene feeds depend on the catalyst used and the desired melt index (or molecular weight) and density (or comonomer content) of the resulting polymer.

[0253] Polymerization in the second polymerization zone is preferably carried out in the gas phase, preferably in a fluidized bed reactor, a fast fluidized bed reactor, or a settling bed reactor, or any combination of these reactors. Polymerization in the second polymerization zone is more preferably carried out in a fluidized bed gas-phase reactor, wherein ethylene is polymerized with 1-butene and / or 1-hexene in the presence of a polymerization catalyst, and preferably in an upward-moving gas stream in the presence of a reaction mixture from the first polymerization zone. This reactor typically comprises a fluidized bed containing polymer particles containing an active catalyst growing above a fluidization grid.

[0254] The polymer bed is fluidized using a fluidizing gas comprising an olefin monomer, a final comonomer, a final chain growth control agent or chain transfer agent (e.g., hydrogen), and a final inert gas. The fluidizing gas is introduced into the inlet chamber at the bottom of the reactor. More than one of the above components can be continuously added to the fluidizing gas to compensate for losses caused by reactions or product extraction.

[0255] The fluidizing gas passes through the fluidized bed. The apparent velocity of the fluidizing gas must be higher than the minimum fluidizing velocity of the particles contained in the fluidized bed; otherwise, fluidization will not occur. On the other hand, the gas velocity should be lower than the initial velocity of the pneumatic conveying; otherwise, the entire bed will be filled with fluidizing gas.

[0256] When fluidized gas comes into contact with a bed containing an active catalyst, the gas's reactive components (e.g., monomers and chain transfer agents) react in the presence of the catalyst to form polymer products. Simultaneously, the gas is heated by the heat of reaction.

[0257] Unreacted fluidized gas is removed from the top of the reactor and cooled in a heat exchanger to remove the heat of reaction. The gas is cooled to a temperature below the bed temperature to prevent the bed from heating up due to the reaction. The gas can be cooled to a temperature at which some of the gas condenses. When liquid droplets enter the reaction zone, they are evaporated.

[0258] The heat of vaporization helps remove the heat of reaction. This operation is called condensation mode, and its variations are disclosed in WO-A-2007 / 025640, USA-4543399, EP-A-699213, and WO-A-94 / 25495. As disclosed in EP-A-696293, a condenser can also be added to the circulating gas stream. The condenser is a non-polymerizable component, such as n-pentane, isopentane, n-butane, or isobutane, which condenses at least partially in the cooler.

[0259] The gas is then compressed and circulated into the reactor's inlet chamber. Fresh reactants are introduced into the fluidizing gas stream before entering the reactor to compensate for losses caused by the reaction and product extraction. It is well known that the composition of the fluidizing gas should be analyzed and gas components introduced to maintain a constant composition. The actual composition is determined by the desired properties of the product and the catalyst used in the polymerization.

[0260] The catalyst can be introduced into the reactor continuously or intermittently in various ways. When the gas-phase reactor is part of a cascade reactor, the catalyst is typically dispersed in polymer particles from a previous polymerization stage. As disclosed in EP-A-1415999 and WO-A-00 / 26258, polymer particles can be introduced into the gas-phase reactor. As disclosed in EP-A-887379, EP-A-887380, EP-A-887381 and EP-A-991684, it is advantageous to introduce the slurry directly into the fluidized bed of the gas-phase reactor, particularly if the preceding reactor is a slurry reactor.

[0261] The polymerization products can be extracted from the gas-phase reactor continuously or intermittently. Combinations of these methods can also be used. Continuous extraction is disclosed in WO-A-00 / 29452. Intermittent extraction is disclosed in US-A-4621952, EP-A-188125, EP-A-250169, and EP-A-579426.

[0262] If desired, antistatic agents such as water, ketones, aldehydes, and alcohols can be introduced into the gas-phase reactor. The reactor may also include a mechanical stirrer to further promote mixing within the fluidized bed.

[0263] Fluidized bed polymerization reactors are typically operated at temperatures of 50 to 100°C, preferably 65 to 90°C. The pressure is preferably 10 to 40 bar, and more preferably 15 to 30 bar.

[0264] The polymerization of the first and second ethylene polymer components in the first and second polymerization zones can be carried out prior to the prepolymerization step. The purpose of prepolymerization is to polymerize a small amount of polymer onto the catalyst at low temperature and / or low monomer concentration. Prepolymerization can improve the performance of the catalyst in the slurry and / or alter the properties of the final polymer.

[0265] The prepolymerization step can be carried out in a slurry or gas phase. Prepolymerization is preferably carried out in a slurry, and more preferably in a circulating reactor. Then, prepolymerization is preferably carried out in an inert diluent, preferably a low-boiling-point hydrocarbon or a mixture of such hydrocarbons having 1 to 4 carbon atoms.

[0266] The temperature in the prepolymerization step is typically 0 to 90°C, preferably 20 to 80°C, and more preferably 25 to 70°C.

[0267] Pressure is not important, typically ranging from 1 to 150 bar, with 10 to 100 bar being preferred.

[0268] Preferably, all catalyst components are introduced into the prepolymerization step.

[0269] Preferably, the reaction product of the prepolymerization step is then introduced into the first polymerization zone.

[0270] Ethylene copolymer (B) obtained from a multi-stage process can be extruded and granulated, and then blended with propylene copolymer (A) in granular form.

[0271] The ethylene copolymer (B) obtained from the multi-stage process can also be blended with the propylene copolymer (A) in powder form.

[0272] Extrusion can be carried out in a manner commonly known in the art, preferably in a twin-screw extruder. An example of a suitable twin-screw extruder is a co-rotating twin-screw extruder. These are manufactured by Coperion or Japan Steel Works. Another example is a counter-rotating twin-screw extruder. Such extruders are manufactured by Kobe Steel and Japan Steel Works.

[0273] Extruders typically consist of a melting section for molten polymer and a mixing section for homogenizing the polymer melt. Melting and homogenization are achieved by introducing energy into the polymer. The more energy introduced into the polymer, the better the homogenization effect. However, excessive energy introduction can lead to polymer degradation and deterioration of mechanical properties. Suitable specific energy input (SEI) levels are from about 200 to about 450 kWh / ton of polymer, preferably 240 to 350 kWh / ton.

[0274] Typically, the average residence time of polymers in an extruder is from about 30 seconds to about 10 minutes. This value depends to some extent on the type of extruder. However, for most extruder types, a value of 1 to 5 minutes is sufficient to balance polymer uniformity and mechanical properties.

[0275] Suitable extrusion methods are disclosed in EP-A-1600276 and WO-A-98 / 15591.

[0276] Before extrusion, the required additives are mixed with the polymer.

[0277] use

[0278] In another aspect, the present invention relates to the use of polypropylene compositions for the manufacture of pipes, said polypropylene compositions having a melt flow rate (MFR2) of 0.1 to 1.0 g / 10 min as measured according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C, and comprising...

[0279] (A) A copolymer of 70 to 95 wt.% of propylene and comonomer units derived from 1-butene or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0280] • Total comonomer content of 0.5 to 5.0 wt.%;

[0281] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 230 °C, from 0.10 to 2.0 g / 10 min; and

[0282] • The ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn), measured by gel permeation chromatography (GPC) from 2.5 to 6.0, according to ISO 16014-4:2003 and ASTM D 6474-99; and

[0283] (B) A copolymer of 5 to 30 wt.% ethylene with comonomer units derived from 1-butene and / or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having:

[0284] • Total comonomer content of 1.0 to 25.0 wt.%;

[0285] ·910.0 to 940.0 kg / m 3 The density measured according to ISO 1183; and

[0286] • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 190 °C, from 0.05 to 3.0 g / 10 min.

[0287] All aspects of the polypropylene compositions and pipes described above or below are also applicable to the uses of this invention.

[0288] The invention is further illustrated below by way of examples.

[0289] Example

[0290] 1. Measurement method:

[0291] Unless otherwise defined, the following terms and measurement methods apply to the above general description of the invention and the following embodiments.

[0292] Quantitative analysis of copolymer microstructure using NMR spectroscopy

[0293] Comonomer determination:

[0294] 1-Hexene content in propylene-1-hexene copolymer

[0295] Using a Bruker Avance III 500 NMR spectrometer, the spectra were observed at 500.13 and 125.76 MHz. 1 H and 13 C performs the operation and records the quantitative value in the molten state. 13 C{ 1 ¹H NMR spectroscopy. All spectra were performed using ¹H NMR spectroscopy. 13A C-optimized 7mm magic angle spin (MAS) probe was used for recording at 180°C, and nitrogen was used for all pneumatic devices. Approximately 200 mg of material was loaded into a 7mm outer diameter zirconia MAS rotor and rotated at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382., Parkinson, M., Klimke, K., S piess,HW,Wilhelm,M.,Macromol.Chem.Phys.2007;208:2128.,Castignolles,P.,Graf,R.,Parkinson,M.,Wilhelm,M.,Gaborieau,M.,Polymer 50(2009)2373). Within a short cyclic delay of 3 seconds, standard single-pulse excitation using NOE was performed (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382., Pollard, M., Klimke, K., Graf, R., Spiess, HW, Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813.) and RS-HEPT decoupling scheme were also tested. (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239., Griffin, JM, Tripon, C., Samoson, A., Filip, C., and Brown, SP, Mag. Res. in Chem. 2007 45, S1, S198). A total of 16384 (16 k) transient values ​​were collected for each spectrum.

[0296] Quantitative 13 C{ 1 The ¹H NMR spectra were processed, integrated, and the relevant quantitative properties were determined by integration. All chemical shifts were internally referenced to the methyl isotactic pentad at 21.85 ppm.

[0297] Observe the characteristic signals corresponding to the incorporation of 1-hexene, and quantify the comonomer content in the following manner.

[0298] The amount of 1-hexene incorporated into the PHP segregating sequence was quantified by integrating the αB4 site at 44.2 ppm as a percentage of the number of reporter sites per comonomer:

[0299] H = I αB4 / 2

[0300] The amount of 1-hexene incorporated into the PHHP bicontinuous sequence was quantified by integrating the ααB4 site at 41.7 ppm as a percentage of the number of reporter sites per comonomer:

[0301] HH=2*I ααB4

[0302] When two consecutive incorporations are observed, the amount of 1-hexene incorporated into the PHP separation sequence needs to be compensated for because the signals αB4 and αB4B4 overlap at 44.4 ppm.

[0303] H = (I αB4 –2*I ααB4 ) / 2

[0304] The total 1-hexene content is calculated based on the sum of isolated and continuously incorporated 1-hexene:

[0305] H 总计 =H+HH

[0306] When no sites indicating continuous incorporation are observed, the total content of 1-hexene comonomer is calculated solely from this amount:

[0307] H 总计 =H

[0308] Characteristic signals indicating region 2,1-red type defects were observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

[0309] The Pαβ(21e8) and Pαγ(21e6) methyl sites located at 17.7 and 17.2 ppm indicate the presence of 2,1-erythromorphic regional defects, which is confirmed by other characteristic signals.

[0310] The total amount of secondary (2,1-erythroform) propylene incorporated was quantified based on the αα21e9 methylene site at 42.4 ppm:

[0311] P 21 =I αα21e9

[0312] The total amount of propylene incorporated in a single (1,2) step was quantified based on the major Sαα methylene site at 46.7 ppm, and after compensating for the relative amounts of 2,1-erythro, αB4, and ααB4B4 methylene units of propylene that were not accounted for (note the H and HH counts of the hexene monomer for each sequence, not the sequence number):

[0313] P 12 =I Sαα +2*P 21 +H+HH / 2

[0314] The total amount of propylene is quantified as the sum of primary (1,2) and secondary (2,1-red) propylene additions:

[0315] P 总计 =P 12 +P 21 =I Sαα +3*I αα21e9 +(I αB4 –2*I ααB4 ) / 2+I ααB4

[0316] Simplified to:

[0317] P 总计 =I Sαα +3*I αα21e9 +0.5*I αB4

[0318] The total mole fraction of 1-hexene in the polymer is calculated as follows:

[0319] f H =H 总计 / (H 总计 +P 总计 )

[0320] The complete integral equation for the molar fraction of 1-hexene in the polymer is:

[0321] f H =((I αB4 –2*I ααB4 ) / 2)+(2*I ααB4 )) / ((I Sαα +3*I αα21e9 +0.5*I αB4 )+

[0322] ((I αB4 –2*I ααB4 ) / 2)+(2*I ααB4 ))

[0323] Simplified to:

[0324] fH =(I αB4 / 2+I ααB4 ) / (I Sαα +3*I αα21e9 +I αB4 +I ααB4 )

[0325] The total amount of 1-hexene comonomer incorporated, expressed as a mole percentage, is calculated by mole fraction in a conventional manner:

[0326] H[mol-%]=100*f H

[0327] The total amount of 1-hexene comonomer incorporated, by weight percentage, is calculated as a mole fraction in the standard manner:

[0328] H[wt.-%]=100*(f H *84.16) / ((f H *84.16)+((1-f H )*42.08))

[0329] The content of 1-butene and 1-hexene comonomers in linear low-density polyethylene (LLDPE)

[0330] Using a Bruker Avance III 500 NMR spectrometer, the spectra were observed at 500.13 and 125.76 MHz. 1 H and 13 C performs the operation and records the quantitative value in the molten state. 13 C{ 1 H NMR spectroscopy. All spectra were performed using H NMR spectroscopy. 13The recording was performed using a C-optimized 7mm magic angle spin (MAS) probe at 150°C, with all pneumatic devices using nitrogen. Approximately 200 mg of material was loaded into a 7mm outer diameter zirconia MAS rotor and rotated at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382., Parkinson, M., Klimke, K., S piess,HW,Wilhelm,M.,Macromol.Chem.Phys.2007;208:2128.,Castignolles,P.,Graf,R.,Parkinson,M.,Wilhelm,M.,Gaborieau,M.,Polymer 50(2009)2373). Within a short cyclic delay of 3 seconds, standard single-pulse excitation was performed using NOE (Pollard, M., Klimke, K., Graf, R., Spiess, HW, Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813., Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.) and RS-HEPT decoupling scheme (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239, Griffin, JM, Tripon, C., Samoson, A., Filip, C., and Brown, SP, Mag. Res. Chem. 2007 45, S1, S198). A total of 1024 (1k) transient values ​​were collected for each spectrum. This setting was chosen because of its high sensitivity to low comonomer content.

[0331] Processing and quantification using a customized automated spectral analysis program. 13 C{ 1 ¹H NMR spectroscopy was performed and quantitative properties were determined. All chemical shifts were internally referenced to the bulk methylene signal (δ+) at 30.00 ppm (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201).

[0332] The amount of ethylene is quantified based on the integral of the number of methylene (δ+) sites at 30.00 ppm relative to the number of reporter sites per monomer:

[0333] E = I δ+ / 2

[0334] Correction of isolated comonomer units based on the number of isolated comonomer units:

[0335] E 总计 =E + (3*B + 2*H) / 2

[0336] Here, B and H are defined for their respective comonomers. Corrections are made in a similar manner when continuous and discontinuous copolymers are incorporated.

[0337] Characteristic signals corresponding to the incorporation of 1-butene were observed (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.) as well as the total amount calculated relative to all other monomers in the polymer.

[0338] The amount of isolated 1-butene incorporated into the EEBEE sequence was quantified by integrating the number of reporter sites per monomer at the *B2 site at 38.3 ppm:

[0339] B = I *B2

[0340] The amount of 1-butene sequentially incorporated into the EEBBEE sequence was quantified by integrating the number of reporter sites per monomer at the ααB2B2 site at 39.4 ppm:

[0341] BB = 2 * I ααB2B2

[0342] The amount of discontinuously incorporated 1-butene into the EEBEBEE sequence was quantified by integrating the number of reporter sites per monomer at the ββB2B2 site at 24.7 ppm:

[0343] BEB = 2 * I ββB2B2

[0344] Since the *B2 and *βB2B2 sites of isolated (EEBEE) and discontinuously incorporated (EEBEBEE)1-butene overlap, the total amount of isolated 1-butene incorporation is corrected based on the amount of discontinuous 1-butene:

[0345] B = I *B2 -2*I ββB2B2

[0346] The total amount of 1-butene is calculated based on the sum of isolated, continuous, and discontinuous incorporations:

[0347] B 总计 =B+BB+BEB

[0348] The total molar fraction of 1-butene in the polymer is calculated as follows:

[0349] f B = (B 总计 ) / (E 总计 +B 总计 +H 总计 )

[0350] Characteristic signals corresponding to the incorporation of 1-hexene were observed (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201) as well as the total amount calculated relative to all other monomers in the polymer.

[0351] The amount of isolated 1-hexene incorporated into the EEHEE sequence was quantified by integrating the number of reporter sites per monomer at the B4 site at 39.9 ppm.

[0352] H = I *B4

[0353] The amount of 1-hexene sequentially incorporated into the EEHHEE sequence was quantified by integrating the number of reporter sites per monomer at the ααB4B4 site at 40.5 ppm:

[0354] HH=2*I ααB4B4

[0355] The amount of discontinuously incorporated 1-hexene into the EEHEHEE sequence was quantified by integrating the number of reporter sites per monomer at the ββB4B4 site at 24.7 ppm:

[0356] HEH=2*I ββB4B4

[0357] Due to the overlap of the ββB2B2 site of discontinuously incorporated (EEBEBEE)1-butene and the ββB4B4 site of discontinuously incorporated (EEHEHEE)1-hexene, it is assumed that the total amount of discontinuously incorporated (EEBEBEE)1-butene is proportional to the amount of isolated 1-butene (B) incorporated, and that the total amount of discontinuously incorporated (EEHEHEE)1-hexene is proportional to the amount of isolated 1-hexene (H).

[0358] The total mole fraction of 1-hexene in the polymer is calculated as follows:

[0359] fH=(H总计 ) / (E 总计 +B 总计 +H 总计 )

[0360] The molar percentage of incorporated comonomers is calculated as a mole fraction:

[0361] B[mol-%]=100*f B

[0362] H[mol-%]=100*f H

[0363] The weight percentage of incorporated comonomers is calculated as a mole fraction:

[0364] B[wt.-%]=100*(f B *56.11) / ((f B *56.11)+(f H *84.16)+((1-(f B +f H ))*28.05))

[0365] H[wt.-%]=100*(f H *84.16) / ((f B *56.11)+(f H *84.16)+((1-(f B +f H ))*28.05))

[0366] Melt flow rate (MFR)

[0367] Melt flow rate (MFR) or melt index (MI) is measured according to ISO 1133. Where different loads are available, the load is usually expressed using a subscript; for example, MFR2 represents a load of 2.16 kg. According to ISO 1133, a temperature is selected for a specific polymer; for example, 230 °C for polypropylene and 190 °C for polyethylene. Therefore, for polypropylene, MFR2 is measured at a temperature of 230 °C and a load of 2.16 kg, while for polyethylene, MFR2 is measured at a temperature of 190 °C and a load of 2.16 kg.

[0368] density

[0369] Density was measured according to ISO 1183-187. Sample preparation was performed by compression molding according to ISO 1872-2:2007.

[0370] Analytical temperature elution fractionation (TRFF) obtained from cross-fraction chromatography (CFC)

[0371] As described by Ortin A., Monrabal B., Sancho-Tello J., Macromol. Symp., 2007, 257, 13-28, the chemical composition distribution and molecular weight distribution, as well as the corresponding average molecular weights (Mn, Mw, and Mv) at a certain elution temperature (polymer crystallinity in solution), were determined by fully automated cross-fraction chromatography (CFC).

[0372] Cross-fractional chromatography (TREF×SEC) was performed using a CFC instrument (PolymerChar, Valencia, Spain). Concentrations were monitored using a four-band IR5 infrared detector (PolymerChar, Valencia, Spain). Approximately 40 mg of polymer sample was dissolved in 25 mL of TCB in a stainless steel container at 150 °C and allowed to stand for 150 min. Once the sample was completely dissolved, 0.5 mL aliquots were loaded into a TREF column and stabilized at 110 °C for a period of time. The polymer was allowed to crystallize and precipitate to 30 °C at a constant cooling rate of 0.1 °C / min. Discontinuous elution was performed using the following temperature steps (30, 40, 50, 60, 70, 75, 80, 84, 88, 92, 95, 98, 100, 102, 104, 106, 108, 110, 115, 120, 130, and 140 °C).

[0373] In the second dimension, GPC analysis was performed using an Agilent Technologies (Churchistrin, UK) GPC system with 3 PLOlexis columns and a 1x Olexis guard column as the stationary phase. 1,2,4-Trichlorobenzene (TCB, stabilized with 250 mg / L 2,6-di-tert-butyl-4-methylphenol) was used as the eluent at a constant flow rate of 1 mL / min at 150 °C. The column assembly was calibrated using universal calibration (according to ISO 16014-2:2003) and narrow MWD polystyrene (PS) standards ranging from at least 15 kg / mol to 11,500 kg / mol. The PS molecular weight was converted to PP molecular weight equivalent using the following Mark Houwink constant.

[0374] KPS = 19 x 10 -3 mL / g, α PS =0.655

[0375] KPP = 19 x 10 -3 mL / g, α PS =0.725

[0376] The calibration data were fitted using a third-order polynomial fit. Data processing was performed using software provided by PolymerChar and a CFC instrument.

[0377] Polymer fractions eluted at temperatures between 31 and 80 °C with logM values ​​between 4.5 and 6.0 were determined.

[0378] Polymer fractions eluted between 31 and 80 °C with molecular weights between logM 4.5 and 6 were calculated based on CFC data as follows:

[0379]

[0380] In discontinuous elution processes (see above), polymer fractions eluted at 30°C are considered sweep fractions and are not included in the above calculations, which begin at 31°C.

[0381] GPC: Average molecular weight, molecular weight distribution, and polydispersity index (M). n M w M w / M n )

[0382] According to ISO 16014-4:2003 and ASTM D 6474-99, the average molecular weight (M) was determined by gel permeation chromatography (GPC). w M n Molecular weight distribution (MWD) and its width are described by the polydispersity index, PDI = M w / M n (where M) n It is the number average molecular weight, M w (This refers to weight-average molecular weight).

[0383] The PolymerChar GPC instrument, equipped with an infrared (IR) detector, was used with 3x Olexis and 1x Olexis guard columns manufactured by Polymer Laboratories, using 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg / L 2,6-di-tert-butyl-4-methylphenol) as the solvent at a constant flow rate of 1 mL / min at 160 °C. 200 μL of sample solution was injected for each analysis. The column assembly was calibrated using universal calibration (according to ISO 16014-2:2003) and narrow MWD polystyrene (PS) standards ranging from at least 15 from 0.5 kg / mol to 11,500 kg / mol. The Mark Houwink constants for PS, PE, and PP were as described in ASTM D 6474-99. All samples were prepared by dissolving 5.0 to 9.0 mg of the polymer in 8 mL (160 °C) of stabilized TCB (same as the mobile phase), with a dissolution time of 2.5 h for PP and a maximum of 3 h for PE. The sample was continuously and gently oscillated in the autosampler of the GPC instrument at a temperature of 160°C.

[0384] DSC analysis, melting temperature (Tm) and crystallization temperature (Tc):

[0385] Samples ranging from 5 to 7 mg were measured using a TA instrument Q2000 differential scanning calorimetry (DSC) method. The DSC was operated according to ISO 11357 / Part 3 / Method C2 in a heating / cooling / heating cycle at a scan rate of 10 °C / min and a temperature range of -30 to +225 °C.

[0386] The crystallization temperature (Tc) and heat of crystallization (Hc) are determined by the cooling step, while the melting temperature (Tm) and enthalpy of melting (Hm) are determined by the second heating step.

[0387] Xylene-soluble substances (XCS)

[0388] The xylene-soluble (XCS) component defined and described in this invention was determined according to ISO 16152: 2.0 g of the polymer was dissolved in 250 mL of p-xylene with stirring at 135 °C. After 30 minutes, the solution was cooled at ambient temperature for 15 minutes, and then allowed to stand at 25 ± 0.5 °C for 30 minutes. The solution was filtered through filter paper into two 100 mL flasks. The solution in the first 100 mL container was evaporated under a nitrogen stream, and the residue was dried under vacuum at 90 °C until constant weight was achieved. The xylene-soluble component (percentage) can be determined as follows:

[0389] XS[%]=(100·m·V0) / (m0·V); m0=initial polymer amount[g]; m=residual weight[g]; V0=initial volume[ml]; V=analytical sample volume[ml].

[0390] Determination of Al and Zr (ICP method)

[0391] Elemental analysis of the catalyst was performed by removing a solid sample of mass M and cooling it on dry ice. The sample was diluted to a known volume V by dissolving it in nitric acid (HNO3, 65%, 5% V) and fresh deionized (DI) water (5% V). This solution was then added to hydrofluoric acid (HF, 40%, 3% V), diluted with deionized water to a final volume V, and allowed to stand for two hours to stabilize.

[0392] Analysis was performed at room temperature using a Thermo Elemental iCAP 6300 inductively coupled plasma optical emission spectrometer (ICP-OES). The spectrometer was calibrated using a blank solution (5% HNO3, 3% HF in deionized water) and six standard Al values ​​of 0.5 ppm, 1 ppm, 10 ppm, 50 ppm, 100 ppm, and 300 ppm, and Hf and Zr values ​​of 0.5 ppm, 1 ppm, 5 ppm, 20 ppm, 50 ppm, and 100 ppm in 5% HNO3 and 3% HF solutions in deionized water.

[0393] Prior to analysis, a resloped calibration was performed using blank samples and standards of 100 ppm Al, 50 ppm Hf, and Zr. A quality control sample (20 ppm Al, 5 ppm Hf, and Zr in a solution of 5% HNO3 and 3% HF in deionized water) was also run to confirm the resloped rate. QC samples were also run after every five samples and at the end of the scheduled analysis group.

[0394] Hafnium content was monitored using lines at 282.022 nm and 339.980 nm, and zirconium content was monitored using a line at 339.198 nm. Aluminum content was monitored using a line at 167.079 nm when the Al concentration in the ICP sample was between 0 and 10 ppm (calibrated to 100 ppm only), and Al content was monitored using a line at 396.152 nm when the Al concentration exceeded 10 ppm.

[0395] The reported values ​​are the average of three consecutive aliquots of the same sample and are correlated with the original catalyst by inputting the original mass and dilution volume of the sample into the software.

[0396] In analyzing the elemental composition of the prepolymerized catalyst, the polymer portion was digested by ashing, allowing the elements to be freely dissolved by acid. The calculated total amount corresponds to the weight percentage of the prepolymerized catalyst.

[0397] Catalyst activity

[0398] Catalyst activity is calculated based on the following formula:

[0399]

[0400] Yield

[0401] Total yield is calculated as follows:

[0402]

[0403] For catalyst activity and yield, catalyst dosage refers to the number of grams of prepolymer catalyst or the number of grams of metallocene in the prepolymer catalyst dosage.

[0404] Degree of prepolymerization (DP): Polymer weight before prepolymerization step / Solid catalyst weight

[0405] The composition of the catalyst (prior to the offline prepolymerization step) was determined by the aforementioned ICP. The metallocene content of the prepolymerization catalyst was calculated based on the ICP data as follows:

[0406] Formula 1

[0407]

[0408] Formula 2

[0409]

[0410] Formula 3

[0411]

[0412] Formula 4

[0413]

[0414] Particle size

[0415] Particle size distribution was measured using a Coulter LS200 particle size analyzer according to ISO 13320-1. This instrument is capable of measuring particle size distributions ranging from 0.4 to 2000 μm. The method is a laser diffraction technique in which a laser beam is directed at the sample traveling in a flow-through cuvette. Heptane was used as the sample fluid.

[0416] First, the polymer sample is pretreated by sieving out particles larger than 2 mm. The sieved sample is then mixed with isopropanol and placed in an ultrasonic device to separate the particles. The pretreated sample is then placed in a sample holder for analysis. The results are calculated using the instrument's computer program.

[0417] The PSD index (also known as SPAN) is defined by the following equation (3):

[0418]

[0419] In the formula, d 50 (Dv 50 ) represents the median particle size, d 90 (Dv 90 This represents 90% of the particles having a diameter smaller than d. 90 Minimum particle size; d 10 (Dv 10This represents 10% of the particles with a diameter smaller than d. 10 The minimum particle size.

[0420] The following particle size and particle size distribution parameters were used in the experiment:

[0421] D v90 = Volume of particles when the cumulative particle size is 90%

[0422] D v10 = Volume of particles when the cumulative particle size is 10%

[0423] D v50 = The volumetric size of particles when the cumulative particle size is 50% (median volumetric particle size),

[0424] SPAN = (D v90 –D v10 ) / D v50 .

[0425] Flexural modulus

[0426] The flexural modulus was determined according to ISO 178. The dimensions of the test sample were 80 × 10 × 4.0 mm. 3 (Length × Width × Thickness), manufactured by injection molding according to ISO 1873-2. The span between the stents is 64 mm, and the testing speed is 2 mm / min.

[0427] Notched impact strength (NIS)

[0428] Charpy notched impact strength (NIS) according to ISO 179 1eA at +23°C, using 80×10×4mm material prepared according to EN ISO 1873-2. 3 Measurements were performed on the injection-molded rod test samples.

[0429] Pipeline pressure test

[0430] The pressure performance of pipes manufactured from the compositions of this invention and comparative compositions was tested according to ISO 1167-1 and ISO 1167-2. Pipes with a diameter of 32 mm and a wall thickness of 3 mm were manufactured on a conventional pipe extrusion production line according to ISO 1167-2 and then subjected to circumferential (circumferential) stresses of 4.6 MPa and 4.9 MPa at 95°C in a water-in-water apparatus according to ISO 1167-1. Failure times were recorded in hours, plus the "still operating" time surface, indicating that the failure time had not yet been reached at the time of filing this patent application.

[0431] Pipeline impact test

[0432] The Charpy impact strength of the pipe was determined according to ISO 9854-2. The sample was cut from the pipe (preparation details are shown below), and the sample size was 50 × 6 × 3 mm. 3 The tests were conducted at 0°C, with 10 samples tested each time. The failure type (fracture / no fracture) and the number of samples for each failure type are reported.

[0433] 2. Polymers used in the examples

[0434] a) Propylene copolymer

[0435] The polymerization of propylene copolymers was carried out on a pilot scale using a circulating-gas phase reactor.

[0436] The polymerization catalyst for polymerizing propylene copolymers is prepared according to the specific embodiments described in WO 2015 / 011135 A1 (formation of catalyst 3 as described in WO 2015 / 011135 A1 with metallocene complex MC1 and methylaluminoxane (MAO) and borate), under the condition that the surfactant is 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3-heptafluoropropoxy)-1-propanol. The metallocene complex (MC1 in WO 2015 / 011135 A1) is prepared as described in WO 2013 / 007650 A1 (metallocene E2 in WO 2013 / 007650A1).

[0437] Hexene is used as a comonomer in all cases, and it is introduced into two reactors (a circulating reactor and a gas-phase reactor) to control the required hexene content in the final product.

[0438] The polymerization conditions are shown in Table 1.

[0439] Table 1: Polymerization conditions of propylene copolymers

[0440]

[0441]

[0442] b) Ethylene copolymer

[0443] The ethylene copolymer used in Example IE1 of this invention is the linear low-density polyethylene of Example IE1 of EP 3 257 895 A1, which has a 1-butene content of 0.3 mol-% (0.6 wt.-%), a 1-hexene content of 2.6 mol-% (8.1 wt.-%), and a density of 918 kg / m³. 3 The melt flow rate MFR2 (190℃, 2.16kg) is 1.5g / 10min.

[0444] 3. Polypropylene compositions and pipes

[0445] To prepare the polypropylene composition of Comparative Example CE, the above-mentioned propylene copolymer was mixed with additives (1000 ppm of Irganox B215 (a 1:2 mixture of pentaerythritol-tetra(3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 6683-19-8) and tris(2,4-di-tert-butylphenyl)phosphite (CAS No. 31570-04-4) produced by BASF) and 500 ppm of calcium stearate produced by Baerlocher) in a co-rotating twin-screw extruder at 220°C.

[0446] To prepare the polypropylene composition of Example IE of the present invention, the above-mentioned propylene copolymer and 15 wt% of ethylene copolymer were mixed with additives (1000 ppm of Irganox B215 (a 1:2 mixture of pentaerythritol tetrakis(3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 6683-19-8) and tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4) produced by BASF, and 500 ppm of calcium stearate produced by Baerloch) in a co-rotating twin-screw extruder at 220°C.

[0447] Manufacture pipes with a diameter of 32 mm and a wall thickness of 3 mm on the Battenfeld Pro pipe extrusion production line. Typical conditions are as follows:

[0448] Melting temperature: 224℃

[0449] Output: 30kg / h

[0450] Screw speed: 38 rpm

[0451] Cooling water temperature: 20℃

[0452] Vacuum spray can: 0.23 bar

[0453] Water flow rate at the calibrator inlet: 4 L / h.

[0454] The properties of the polypropylene compositions and pipes for CE and IE are listed in Table 2.

[0455] Table 2: Performance of CE and IE Combinations and Pipelines

[0456]

[0457] NB = No break

[0458] *The test has stopped; no failures were found.

[0459] Figure 1 The TREF fractionation plots and corresponding viscosity-average molecular weights of IE1 and CE1 obtained by CFC analysis are shown.

[0460] Figure 2 The CFC profile of IE1 is shown. The claimed polymer fractions with elution temperatures between 31 and 80 °C and logM between 4.5 and 6 are indicated by squares.

[0461] Figure 3 The CFC profile of CE1 is shown. The claimed polymer fractions with elution temperatures between 31 and 80 °C and logM between 4.5 and 6 are indicated by squares.

[0462] In Example IE, the pipe manufactured according to the present invention exhibits a good balance of performance in terms of good surface quality, acceptable pressure resistance, and improved impact resistance. In contrast, the pipe of Comparative Example CE fractured in a pipe impact test at 0°C.

Claims

1. A pipe comprising a polypropylene composition, wherein, The polypropylene composition comprises (A) A copolymer of 70 to 95 wt.% of propylene and comonomer units derived from 1-butene or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having: • Total comonomer content of 0.5 to 5.0 wt.%; • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 230 °C, from 0.10 to 2.0 g / 10 min; and • The ratio of weight-average molecular weight (Mw / Mn) to number-average molecular weight, measured by gel permeation chromatography (GPC) according to ISO 16014-4:2003 and ASTM D 6474-99, ranging from 2.5 to 6.0; and (B) A terpolymer of 5 to 30 wt.% of ethylene and comonomer units derived from 1-butene and 1-hexene, based on the total weight of the polypropylene composition, said terpolymer having: • Total comonomer content of 1.0 to 25.0 wt.%; ·910.0 to 940.0 kg / m 3 The density measured according to ISO 1183; as well as • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 190 °C, from 0.05 to 3.0 g / 10 min; The polypropylene composition, as determined according to ISO 1133, has a melt flow rate (MFR2) of 0.1 to 1.0 g / 10 min at a load of 2.16 kg and a temperature of 230°C, and a xylene cold soluble content (XCS) of 1.0 to 3.5 wt.- as determined according to ISO 16152.

2. The pipe according to claim 1, wherein, The polypropylene composition has a polymer fraction eluted at a temperature of 31 to 80°C, excluding the sweep fraction, with a logM between 4.5 and 6.0, and the amount of the polymer fraction determined by cross fractionation chromatography (CFC) is 4 to 25 wt.-%, and / or the polypropylene composition has a characteristic chromatogram of the temperature elution fractionation (TREF) obtained from cross fractionation chromatography (CFC) analysis containing two peaks, wherein the first peak Tp(1) elutes between 45 and 90°C and the second peak Tp(2) elutes between 85 and 100°C.

3. The pipe according to claim 1, wherein, The polypropylene composition has a flexural modulus of 700 to 1000 MPa, which is determined according to ISO 178 for injection-molded specimens prepared according to EN ISO 1872-2.

4. The pipe according to claim 1, wherein, The polypropylene composition has a Charpy notched impact strength of 7.5 to 15.0 kJ / m² at 23°C and / or a Charpy notched impact strength of 2.5 to 5.0 kJ / m² at 0°C and / or a Charpy notched impact strength of 1.5 to 4.0 kJ / m² at -20°C. The Charpy notched impact strength is determined according to ISO 179 1eA for injection-molded specimens prepared according to EN ISO1872-2.

5. The pipe according to claim 1, wherein, The polypropylene composition has one or more of the following properties: • The melting temperature Tm, as measured according to ISO 11357 / Part 3, is 135 to 145 °C; • The crystallization temperature Tc, as measured according to ISO 11357 / Part 3, is 100 to 110 °C; and / or • The enthalpy of fusion Hm, as measured according to ISO 11357 / Part 3, is 30 to 45 J / g.

6. The pipe according to claim 1, wherein, The propylene copolymer (A) has one or more of the following properties: • The content of xylene cold solubles (XCS), as determined according to ISO 16152, is 0.2 to 2.5 wt.-%. • The melting temperature Tm, as measured according to ISO 11357 / Part 3, is 135 to 145 °C; • The crystallization temperature Tc, as measured according to ISO 11357 / Part 3, is 100 to 105 °C; and / or • The enthalpy of fusion Hm, as measured according to ISO 11357 / Part 3, is 70 to 80 J / g.

7. The pipe according to claim 1, wherein, The propylene copolymer (A) is obtained by polymerization in the presence of a single-point catalyst system, wherein the catalyst system comprises: (i) Catalysts having the following structures: ， In the formula, M represents zirconium or hafnium; Each X is an independent σ-donor ligand. L is the formula -(ER) 10 2) y - the bridge foundation; y is 1 or 2; E is either C or Si; Each R 10 Independently for C1-C 20 Hydrocarbon group, tri(C1-C) 20 Alkyl)silyl, C6-C 20 Aryl, C7-C 20 Aryl or C7-C 20 alkylaryl, or L is alkylene; R 1 They are either independently the same or different from each other, and are CH2-R 11 Group, wherein R 11 It is H or a straight-chain or branched C1-C6 alkyl, C3-C8 cycloalkyl, C6-C 10 Aryl; R 3 R 4 and R 5 Each is independently identical or different from the others, and is H or a straight-chain or branched C1-C6 alkyl, C7-C 20 Aryl group, C7-C 20 Alkyl or C6-C 20 aryl, provided that there are four or more R groups different from H. 3 R 4 and R 5 Group, then R 3 R 4 and R 5 One or more of them are not tert-butyl; R 7 and R 8 They are either independently the same or different from each other, and are H, CH2-R 12 Group, wherein R 12 It is H or a straight-chain or branched C1-C6 alkyl group, SiR 13 3. GeR 13 3. OR 13 SR 13 NR 13 2, Among them, R 13 It is a straight-chain or branched C1-C6 alkyl, C7-C 20 Alkyl and C7-C 20 Aryl or C6-C 20 Aryl, R 9 Each is independently identical or different from the others, and is an H or a straight-chain or branched C1-C6 alkyl group; and R 2 and R 6 All are H; and (ii) A cocatalyst system containing an aluminoxane cocatalyst.

8. The pipe according to claim 1, wherein, The ethylene copolymer (B) is a terpolymer of ethylene and a comonomer unit selected from 1-butene and 1-hexene, wherein the terpolymer contains 0.1 to 5.0 wt.- of 1-butene and 5.0 to 24.9 wt.- of 1-hexene.

9. The pipe according to claim 1, wherein, The intrinsic viscosity (iV) of the ethylene copolymer (B) measured in decahydronaphthalene at 135°C according to DIN ISO 1628 / 1 in October 1999 is 1.5 to 2.5 dl / g.

10. The pipe according to claim 1, wherein, The ethylene copolymer (B) is obtained by polymerization in the presence of a single-point catalyst system.

11. The pipe according to claim 1, wherein the pipe is a pressure pipe or a pressure pipe for hot and cold water.

12. A method for manufacturing a pipe according to any one of claims 1 to 11, comprising the following steps: a) In the presence of a single-point catalyst system, propylene and 1-butene or 1-hexene are polymerized in a multi-stage process to obtain a copolymer of propylene and comonomer units derived from 1-butene or 1-hexene (A). b) Blending the propylene copolymer (A) and ethylene with a terpolymer (B) derived from comonomer units of 1-butene and 1-hexene to obtain a polypropylene composition; and c) Pipes are made from the polypropylene composition.

13. The method according to claim 12, wherein, The multi-stage process is a sequential polymerization process having at least two polymerization reactors connected in series.

14. The method according to claim 12, wherein, The catalyst system comprises: (i) Catalysts having the following structures: ， In the formula, M represents zirconium or hafnium; Each X is an independent σ-donor ligand. L is the formula -(ER) 10 2) y - the bridge foundation; y is 1 or 2; E is either C or Si; Each R 10 Independently for C1-C 20 Hydrocarbon group, tri(C1-C) 20 Alkyl)silyl, C6-C 20 Aryl, C7-C 20 Aryl or C7-C 20 alkylaryl, or L is alkylene; R 1 They are either independently the same or different from each other, and are CH2-R 11 Group, wherein R 11 It is H or a straight-chain or branched C1-C6 alkyl, C3-C8 cycloalkyl, C6-C 10 Aryl; R 3 R 4 and R 5 Each is independently identical or different from the others, and is H or a straight-chain or branched C1-C6 alkyl, C7-C 20 Aryl group, C7-C 20 Alkyl or C6-C 20 aryl, provided that there are four or more R groups different from H. 3 R 4 and R 5 Group, then R 3 R 4 and R 5 One or more of them are not tert-butyl; R 7 and R 8 They are either independently the same or different from each other, and are H, CH2-R 12 Group, wherein R 12 It is H or a straight-chain or branched C1-C6 alkyl group, SiR 13 3. GeR 13 3. OR 13 SR 13 NR 13 2, Among them, R 13 It is a straight-chain or branched C1-C6 alkyl, C7-C 20 Alkyl and C7-C 20 Aryl or C6-C 20 Aryl, R 9 Each is independently identical or different from the others, and is an H or a straight-chain or branched C1-C6 alkyl group; and R 2 and R 6 All are H; and (ii) A cocatalyst system containing an aluminoxane cocatalyst.

15. Use of polypropylene compositions in the manufacture of pipes, wherein, The polypropylene composition has a melt flow rate (MFR2) of 0.1-1.0 g / 10 min as measured according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C, and a xylene cold soluble content (XCS) of 1.0 to 3.5 wt.% as measured according to ISO 16152, and contains... (A) A copolymer of 70 to 95 wt.% of propylene and comonomer units derived from 1-butene or 1-hexene, based on the total weight of the polypropylene composition, said copolymer having: • Total comonomer content of 0.5 to 5.0 wt.%; • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 230 °C, from 0.10 to 2.0 g / 10 min; and • The ratio of weight-average molecular weight (Mw / Mn) to number-average molecular weight, measured by gel permeation chromatography (GPC) according to ISO 16014-4:2003 and ASTM D 6474-99, ranging from 2.5 to 6.0; and (B) A terpolymer of 5 to 30 wt.% of ethylene and comonomer units derived from 1-butene and 1-hexene, based on the total weight of the polypropylene composition, said terpolymer having: • Total comonomer content of 1.0 to 25.0 wt.%; ·910.0 to 940.0 kg / m 3 The density measured according to ISO 1183; as well as • Melt flow rate MFR2, measured according to ISO 1133, at a load of 2.16 kg and a temperature of 190 °C, from 0.05 to 3.0 g / 10 min.

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