Multimodal polyethylene

Abstract

The present invention relates to an ethylene copolymer consisting of or comprising 55 to 80 wt% of an ethylene homopolymer component A and 20 to 45 wt% of an ethylene copolymer component B of ethylene and an olefin comonomer, wherein the component A has a melt flow index of 80 to 400 dg / min measured according to ISO 1133-1 :2011 at 190 °C and 1.2 kg and a density of at least 968 kg / m 3 3, and wherein the ethylene copolymer has a melt flow index of 0.05 to 0.3 dg / min measured according to ISO 1133-1 :2011 at 190 °C and 5 kg, a density of 956 to 962 kg / m 3 3, a comonomer content of 0.03 to 0.30 mol%, a viscosity value η0.05 at a temperature of 190 °C and a shear rate of 0.05 rad / s of 200 to 1000 kPa.s, and a viscosity value η300 at a temperature of 190 °C and a shear rate of 300 rad / s of 700 to 1500 Pa.s.

Description

[0001] This invention relates to multimodal ethylene copolymers, preferably bimodal ethylene copolymers, and the use of such ethylene copolymers in articles such as pipes.

[0002] Multimodal ethylene copolymers are used in many applications, such as pipelines.

[0003] EP3647645 discloses a component with a capacity of 950.0 kg / m³. 3 Up to 962.0 kg / m 3 A polyethylene composition based on a base resin of a certain density, wherein the polyethylene composition has a melt flow rate MFR21 (190°C, 21.16 kg) of 1.0 to 9.0 g / 10 min as determined according to ISO 1133 and a viscosity η at a constant shear stress of 747 Pa of 3500 kPa·s to 20000 kPa·s. 747 Furthermore, in an embodiment, a pipe manufactured from this composition was found to have a pressure resistance of approximately 2000 hours, as measured according to ISO 1167-1:2006, under a circumferential stress of 12.9 MPa at a temperature of 20°C.

[0004] WO2020088987 discloses a component with a capacity of 952.0 kg / m³. 3 Up to 960.0 kg / m 3 The polyethylene composition is based on a base resin with a density of [insert density here]. The polyethylene composition has a melt flow rate MFR21 (190°C, 21.16 kg) of 1.0 to 7.5 g / 10 min as determined according to ISO 1133, a complex viscosity η0.05 at a frequency of 0.05 rad / s of 750 kPa·s to 1900 kPa·s as determined according to ISO 6721-1 and ISO 6721-10, and a white spot rating not exceeding 12.0 as determined according to ISO 18553. Furthermore, in examples, pipes manufactured from this composition were found to have a pressure resistance of 6 to 70 hours under circumferential stress of 7.0 MPa at 80°C as determined according to ISO 1167-1:2006.

[0005] EP 2599828 A1 discloses a method containing a concentration greater than 950 kg / m² as determined according to ISO 1183-1:2004. 3 And equal to or less than 965 kg / m 3 A polyethylene composition based on a base resin of a certain density, wherein the composition has a melt flow rate MFR5 (190°C, 5 kg) equal to or less than 0.1 g / 10 min as determined according to ISO 1133, and a Pa·s equal to or greater than 3.0 Pa. -1 And equal to or less than 4.5 Pa -1 The polydispersity index Pl within the range.

[0006] WO 2018 / 234110 A1 discloses a polymer composition comprising a base resin, wherein the base resin comprises a very high molecular weight polyethylene component, a low molecular weight polyethylene component having a weight-average molecular weight lower than that of the very high molecular weight polyethylene component, and a high molecular weight polyethylene component having a weight-average molecular weight higher than that of the low molecular weight polyethylene component but lower than that of the very high molecular weight polyethylene component. The composition has a complex viscosity η at 0.05 rad / s equal to or greater than 800 kPa·s. 0,05rad / s The viscosity (η747) at a shear stress of 747 Pa is equal to or less than 34000 kPa·s, and the melt flow rate (MFR5) is equal to or less than 0.17 g / 10 min.

[0007] Pressure resistance is important for many applications, including piping. Impact resistance and processability at both low and high temperatures are also important. Furthermore, the surface appearance of products such as pipes is crucial. While polyethylene is known to be satisfactory for some applications, there remains a need for ethylene copolymers that offer a combination of high pressure resistance, high impact strength, and high processability, allowing for the production of products with a good surface appearance.

[0008] The object of this invention is to provide an ethylene copolymer that satisfies the above and / or other needs.

[0009] Therefore, the present invention provides an ethylene copolymer comprising or consisting of 55 to 80 wt% of an ethylene homopolymer component A and 20 to 45 wt% of an ethylene copolymer component B of ethylene and olefin comonomers.

[0010] Component A has a melt flow index of 80 to 400 dg / min and a melt flow rate of at least 968 kg / m³, measured according to ISO 1133-1:2011 at 190 °C and 1.2 kg. 3 The density, and wherein the ethylene copolymer has a melt flow index of 0.05 to 0.3 dg / min, measured according to ISO 1133-1:2011 at 190 °C and 5 kg, and a melt flow index of 956 to 962 kg / m³. 3 The density, comonomer content of 0.03 to 0.30 mol%, viscosity value η0.05 at 190 °C and 0.05 rad / s at 200 to 1000 kPa·s, and viscosity value η300 at 190 °C and 300 rad / s at 700 to 1500 kPa·s.

[0011] Surprisingly, the ethylene copolymers according to the present invention have a combination of high pressure resistance, high impact strength at low and high temperatures, and high processability, and allow for the production of products with good surface appearance.

[0012] The ethylene copolymer according to the invention is a multimodal ethylene copolymer. Preferably, the ethylene copolymer according to the invention is a bimodal ethylene copolymer, i.e., it consists of components A and B. However, the ethylene copolymer according to the invention may contain one or more additional ethylene polymer components.

[0013] Preferably, the total amount of components A and B relative to the ethylene copolymer is at least 80% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight, at least 99% by weight, or 100% by weight.

[0014] ethylene copolymer

[0015] Ethylene copolymers are polymers that are largely (by weight) derived from ethylene monomer units. Ethylene copolymers can be copolymers of ethylene and C3-C20 comonomers. The C3-C20 comonomers are preferably selected from C3-10 α-olefins, such as propylene, 1-butene, 1-hexene, and 1-octene. Most preferably, the ethylene copolymer is a copolymer of ethylene and 1-hexene.

[0016] The ethylene copolymer according to the invention has a comonomer content of 0.03-0.30 mol%, preferably 0.10-0.20 mol%.

[0017] The ethylene copolymer according to the invention has a melt flow index (sometimes referred to herein as MI5) of 0.05 to 0.3 dg / min, preferably 0.08 to 0.27 dg / min, more preferably 0.10 to 0.24 dg / min, measured according to ISO 1133-1:2011 at 190 °C and 5 kg.

[0018] Preferably, the ethylene copolymer according to the invention has a melt flow index (sometimes referred to herein as MI21.6) of 5 to 15 dg / min, more preferably 8 to 14 dg / min, measured according to ISO 1133-1:2011 at 190°C and 21.6 kg.

[0019] The ethylene copolymer according to the invention has a content of 956 to 962 kg / m³. 3 Optimal weight is 958 to 960 kg / m³ 3 The density.

[0020] The ethylene copolymer according to the invention has a viscosity value η of 200 to 1000 kPa·s, preferably 220 to 500 kPa·s, at a temperature of 190°C and a shear rate of 0.05 rad / s. 0.05 This low viscosity at low shear rates results in better surface appearance and better uniformity in products made from this copolymer.

[0021] The ethylene copolymer according to the invention has a viscosity value η of 700 to 1500 Pa·s, preferably 800 to 1200 Pa·s, at a temperature of 190°C and a shear rate of 300 rad / s. 300 This low viscosity at high shear rates provides better processability.

[0022] The viscosity value was determined according to the method described in the experimental section.

[0023] In some particularly preferred embodiments, the ethylene copolymer is a copolymer of ethylene and 1-hexene, and has a melt flow index of 0.10 to 0.24 dg / min measured according to ISO 1133-1:2011 at 190°C and 5 kg, a melt flow index of 8 to 14 dg / min measured according to ISO 1133-1:2011 at 190°C and 21.6 kg, and a melt flow index of 958 to 960 kg / m 3 The density, viscosity η at 190°C and a shear rate of 0.05 rad / s, ranging from 220 to 500 kPa·s. 0.05 And the viscosity η at 190°C and a shear rate of 300 rad / s, ranging from 800 to 1200 Pa·s. 300 .

[0024] Preferably, the ethylene copolymer according to the invention has a strain hardening of 40 to 70 MPa, preferably 45 to 60 MPa, as determined according to ISO 18488.

[0025] Preferably, the ethylene copolymer according to the invention has a yield stress of 20 to 32 MPa as determined at 23°C according to ISO 527-1.

[0026] Preferably, the ethylene copolymer according to the invention has a strength of at least 20 kJ / m³ as determined according to ISO 179-1 / 1eA at -30°C. 2 Charpy impact strength.

[0027] Preferably, the ethylene copolymer according to the invention has a strength of at least 20 kJ / m³ as determined according to ISO 179-1 / 1eA at 0°C. 2 Charpy impact strength.

[0028] Preferably, the ethylene copolymer according to the invention has a strength of at least 20 kJ / m³ as determined according to ISO 179-1 / 1eA at 23°C. 2 Charpy impact strength.

[0029] Ethylene homopolymer component A

[0030] Component A is an ethylene homopolymer.

[0031] Preferably, the ethylene polymer component A has a content of at least 968 kg / m³. 3 More preferably 968 to 975 kg / m 3 The density.

[0032] Preferably, component A has a melt flow index of 80 to 400 dg / min, more preferably 100 to 200 dg / min, as measured according to ISO 1133-1:2011 at 190°C and 1.2 kg.

[0033] The amount of component A relative to the ethylene copolymer according to the invention is 55 to 80% by weight, preferably 58 to 70% by weight, more preferably 60 to 65% by weight.

[0034] Ethylene copolymer component B

[0035] Component B is a copolymer of ethylene and a C3-C20 comonomer. The C3-C20 comonomer is preferably selected from C3-10 α-olefins, such as propylene, 1-butene, 1-hexene, and 1-octene. Most preferably, component B is a copolymer of ethylene and 1-hexene.

[0036] The amount of component B relative to the ethylene copolymer according to the invention is 20 to 45% by weight, preferably 30 to 42% by weight, more preferably 35 to 40% by weight.

[0037] Methods for preparing ethylene copolymers

[0038] The ethylene copolymer according to the invention can be prepared by a method comprising melt-mixed or solution-blended components A and B and optionally additional ethylene polymer components prepared in different reactors. Melt-mixing or solution blending can be carried out in any conventional blending equipment. Components A and B to be melt-mixed or solution-blended and optionally additional ethylene polymer components can be produced by any known method.

[0039] Alternatively, the ethylene copolymer of the present invention can be prepared by a method comprising polymerizing component A and subsequently polymerizing component B in the presence of component A. Therefore, the present invention provides a method for preparing the ethylene copolymer according to the present invention, wherein the method comprises a sequential polymerization method comprising at least two reactors connected in series, wherein the method comprises the following steps:

[0040] - Component A is prepared using the first set of conditions in the first reactor.

[0041] - Transfer component A and optional unreacted monomers from the first reactor to the second reactor.

[0042] - The monomer is fed into the second reactor, and

[0043] - Component B is prepared in the second reactor in the presence of component A.

[0044] In this case, the properties of the fraction produced in the second reactor can be inferred from the polymer, which is prepared individually in a single stage by applying the same polymerization conditions (e.g., the same temperature, reactant / diluent partial pressure, suspension medium, and reaction time) as the stage of the multi-stage method in which the fraction is produced, and by using a catalyst on which the previously prepared polymer is not present. Alternatively, it can also be, for example, according to B. Conference on Polymer Processing (The Polymer Processing Society), Extended Abstracts and Final Programme, Gothenburg, August 19-21, 1997, 4:13. The properties of the fractions produced in higher stages of a multi-stage method can also be calculated according to KBM McAuley, JFMc Gregor, AIChE Journal, Vol. 37, No. 6, 825-835, June 1991.

[0045] Therefore, although the products of a multi-stage method cannot be directly measured, the characteristics of fractions produced in the higher stages of such a method can be determined by applying one or two of the methods described above. Those skilled in the art will be able to select the appropriate method.

[0046] When component A from the first reactor is transferred to the second reactor, unreacted monomers may also be transferred to the second reactor, or unreacted monomers may be partially or completely removed in an inter-reactor operating unit such as a flash evaporation step.

[0047] catalyst

[0048] Each of the ethylene polymer components A and B, and optionally other ethylene polymer components, can be produced in the presence of a known catalyst system, such as a Ziegler-Natta catalyst system or a metallocene catalyst system, preferably a Ziegler-Natta catalyst system. Polymerization can be carried out in the presence of an antistatic agent or antifouling agent, for example, in an amount of 1 to 500 ppm relative to the total amount of reactor contents.

[0049] Preferably, the catalyst system comprises

[0050] (I) Solid reaction products obtained by reactions a) and b):

[0051] a) a hydrocarbon solution comprising 1) and 2),

[0052] 1) an oxygen-containing organic magnesium compound or a halogen-containing magnesium compound, and

[0053] 2) an oxygen-containing organic titanium compound, and

[0054] b) aluminum halide having the formula AlR n nX 3-n , wherein R is a hydrocarbon moiety having 1 to 10 carbon atoms, X is halogen, and 0 < n < 3, and

[0055] (II) an aluminum compound having the formula AlR3, wherein R is a hydrocarbon moiety having 1 to 10 carbon atoms.

[0056] During the reaction of the hydrocarbon solution comprising the oxygen-containing organic magnesium compound and the oxygen-containing organic titanium compound with component (I b), a solid catalyst precursor precipitates, and after the precipitation reaction, the resulting mixture is heated to complete the reaction.

[0057] The aluminum compound (II) is metered in before or during polymerization, and may be referred to as a cocatalyst.

[0058] The polymerization process may be a slurry polymerization process.

[0059] Preferably, the diluent in the slurry polymerization process is a diluent composed of an aliphatic hydrocarbon compound, which has an atmospheric boiling point of at least 35 °C, more preferably higher than 55 °C. Suitable diluents are hexane and heptane. The preferred diluent is hexane.

[0060] Suitable oxygen-containing organic magnesium compounds include, for example, magnesium alkoxides, such as magnesium methoxide, magnesium ethoxide and magnesium isopropoxide; and alkyl alkoxides, such as ethyl magnesium ethoxide; and so-called carbonated magnesium alkoxides, such as ethyl magnesium carbonate.

[0061] Preferably, the oxygen-containing organic magnesium compound is magnesium alkoxide. Preferably, the magnesium alkoxide is magnesium ethoxide Mg(OC2H5)2.

[0062] Suitable halogen-containing magnesium compounds include, for example, magnesium dihalide and magnesium dihalide complexes, wherein the halogen is preferably chlorine.

[0063] Preferably, the hydrocarbon solution comprises the oxygen-containing organic magnesium compound as (I)(a)(1).

[0064] Suitable oxygen-containing organic titanium compounds can be represented by the general formula [TiO x x(OR) 4-2x n] n , wherein R represents an organic moiety, x is from 0 to 1, and n is from 1 to 6.

[0065] Suitable examples of organic oxygen-containing titanium compounds include alkoxides, phenoxides, oxidized alkoxides, condensed alkoxides, carboxylates and enolates. The organic oxygen-containing titanium compound is preferably titanium alkoxide. Suitable alkoxides include, for example, Ti(OC2H5)4, Ti(OC3H7)4, Ti(OC4H9)4 and Ti(OC8H 17 )4. The preferred organic oxygen-containing titanium compound is Ti(OC4H9)4.

[0066] Preferably, the aluminum halide is of the formula AlR n X 3-n wherein R is a hydrocarbon moiety having 1 to 10 carbon atoms, X is halogen and 0.5<n<2. Suitable examples of the aluminum halide in (I)b of the formula AlR n X 3-n include ethyl aluminum dibromide, ethyl aluminum dichloride, propyl aluminum dichloride, n-butyl aluminum dichloride, isobutyl aluminum dichloride, diethyl aluminum chloride and diisobutyl aluminum chloride. X is preferably Cl. The organoaluminum halide in (I)b) is preferably organoaluminum chloride, more preferably the organoaluminum halide in (I)b) is selected from the group consisting of ethyl aluminum dichloride, diethyl aluminum chloride, isobutyl aluminum dichloride, diisobutyl aluminum chloride and mixtures thereof.

[0067] Generally, the molar ratio of Al in I b) to Ti in I a) is from 3:1 to 16:1. According to a preferred embodiment of the present invention, the molar ratio of Al in I b) to Ti in I a) is from 6:1 to 10:1.

[0068] Suitable examples of cocatalysts of formula AlR3 include triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum and trioctylaluminum. The aluminum compound in (II) of formula AlR3 is preferably triethylaluminum or triisobutylaluminum.

[0069] Hydrocarbon solutions of organic oxygen-containing magnesium compounds and organic oxygen-containing titanium compounds can be prepared according to procedures disclosed, for example, in US 4178300 and EP 0876318. The solution is generally a clear liquid. If any solid particles are present, these can be removed by filtration before the solution is used in catalyst synthesis.

[0070] Generally, the molar ratio of magnesium to titanium is lower than 3:1, preferably the molar ratio of magnesium to titanium is from 0.2:1 to 3:1.

[0071] Generally, the molar ratio of aluminum in (II) to titanium in (a) is from 1:1 to 300:1, preferably the molar ratio of aluminum in (II) to titanium in (a) is from 3:1 to 100:1.

[0072] The catalyst can be obtained through the following steps: a first reaction between a magnesium alkoxide and a titanium alkoxide, followed by dilution with a hydrocarbon solvent to produce a soluble complex consisting of the magnesium alkoxide and the titanium alkoxide, and subsequently, a hydrocarbon solution of the complex reacting with a solvent having the formula AlR n X 3-n The reaction between organoaluminum halides.

[0073] Optionally, an electron donor may be added during the preparation of the solid catalytic complex (simultaneously with subsequent steps or in another step) or during the polymerization stage. The addition of an electron donor is disclosed, for example, in WO2013087167.

[0074] Generally speaking, it has the formula AlR n X 3-n Aluminum halides are used as solutions in hydrocarbons. Any hydrocarbon that does not react with organoaluminum halides is suitable for use as a hydrocarbon.

[0075] The order of addition could be to add a hydrocarbon solution containing organic oxygen-containing magnesium compounds and organic oxygen-containing titanium compounds to a hydrocarbon solution having the formula AlR n X 3-n Compounds or the opposite.

[0076] The temperature used for this reaction can be any temperature below the boiling point of the hydrocarbon used. Generally, the duration of the addition is preferably less than 1 hour.

[0077] In hydrocarbon solutions containing organic oxygen-containing magnesium compounds and organic oxygen-containing titanium compounds with the formula AlR n X 3-n In the reaction of organoaluminum halides, the solid catalyst precursor precipitates. After precipitation, the resulting mixture is heated for a certain period to terminate the reaction. The precipitate is then filtered and washed with hydrocarbons. Other methods for separating the solid from the diluent and subsequent washing can also be applied, such as multiple decantation steps. All steps should be carried out under an inert atmosphere of nitrogen or another suitable inert gas.

[0078] Other aspects

[0079] The present invention further relates to compositions comprising the ethylene copolymer according to the invention. The composition may consist of the ethylene copolymer according to the invention and additives such as pigments, nucleating agents, antistatic agents, fillers, antioxidants, etc. Typically, the amount of the ethylene copolymer relative to the composition is 90 to 99.9% by weight, for example, at least 95% by weight, at least 98% by weight, or at least 99% by weight. Typically, the amount of the additives is 0.1 to 10% by weight relative to the composition, for example, at most 5% by weight, at most 2% by weight, or at most 1% by weight.

[0080] The density of the composition according to the invention can be substantially the same as the density of the ethylene copolymer according to the invention. When the composition contains pigments and / or fillers such as carbon black, the density of the ethylene copolymer composition can be from 956 to 974 kg / m³. 3 For example, 958 to 972 kg / m 3 .

[0081] The present invention further relates to articles comprising the ethylene copolymer according to the invention or compositions according to the invention. Preferably, the articles are extruded articles such as pipes.

[0082] Preferably, the pipe according to the invention has a pressure resistance of at least 1000 hours at 20°C and under circumferential stress of 13.0 MPa using a type A end cap, as determined according to ISO 1167-1:2006, and / or a pressure resistance of at least 5000 hours at 20°C and under circumferential stress of 12.8 MPa using a type A end cap, as determined according to ISO 1167-1:2006.

[0083] It should be noted that the present invention relates to all possible combinations of the features described herein, particularly those combinations of the features present in the preferred claims. Therefore, it should be understood that this document discloses all combinations of features relating to compositions according to the invention; all combinations of features relating to methods according to the invention; and all combinations of features relating to compositions according to the invention and features relating to methods according to the invention.

[0084] It should be further noted that the terms "comprising," "including," and "containing" do not exclude the presence of other elements. However, it should also be understood that a description of a product / composition comprising certain components also discloses a product / composition composed of those components. A product / composition composed of these components can be advantageous because it provides a simpler and more economical method for preparing the product / composition. Similarly, it should be understood that a description of a method including certain steps also discloses a method composed of those steps. A method composed of these steps can be advantageous because it provides a simpler and more economical method.

[0085] When the lower and upper limits of a parameter are mentioned, it should also be understood that the range formed by the combination of the lower and upper limits is disclosed.

[0086] The present invention is illustrated by the following examples, but is not intended to limit the invention.

[0087] Catalyst preparation

[0088] Catalyst 1

[0089] 100 g of granular Mg(OC2H5)2 and 150 mL of Ti(OC4H9)4 were introduced into a 2 L round-bottom flask equipped with a reflux condenser and a stirrer. The mixture was heated to 180 °C with gentle stirring, followed by stirring for 1.5 h. During this time, a clear liquid was obtained. The mixture was cooled to 120 °C and then diluted with 1480 mL of hexane. Upon addition of hexane, the mixture was further cooled to 67 °C. The mixture was maintained at this temperature for 2 h and then cooled to room temperature. The resulting clear solution was stored under a nitrogen atmosphere and used as obtained. Analysis of the solution showed a titanium concentration of 0.25 mol / L.

[0090] In a 1.0-liter glass reactor equipped with baffles, a reflux condenser, and a stirrer, 286 ml of hexane and 170 ml of the complex obtained above were metered in. The stirrer was set to 1400 rpm. In a separate flask, 75 ml of a 50% ethylaluminum dichlorodichloro(EADC) solution was added to 43 ml of hexane. The resulting EADC solution was metered into the reactor over 15 minutes using a peristaltic pump. The mixture was then refluxed for 2 hours. After cooling to ambient temperature, the resulting red / brown suspension was transferred to a glass P4 filter and the solids were separated. The solids were washed four times with 500 ml of hexane. The solids were absorbed in 0.3 L of hexane, and the resulting slurry was stored under nitrogen. The solids content was 30 g / L.

[0091] Catalyst analysis results:

[0092] Ti 9.7 wt%; Mg 10.4 wt%; Al 4.6 wt%; Cl 49 wt%; OEt 9.0 wt%; OBu 12 wt%.

[0093] Catalyst 2 (WO2017 / 009058, page 9, line 13 to page 10, line 4)

[0094] Preparation of hydrocarbon solutions containing organic oxygen-containing magnesium compounds and organic oxygen-containing titanium compounds

[0095] 100 g of granular Mg(OC2H5)2 and 150 mL of Ti(OC4H9)4 were introduced into a 2 L round-bottom flask equipped with a reflux condenser and a stirrer. The mixture was heated to 180 °C with gentle stirring, followed by stirring for 1.5 h. During this time, a clear liquid was obtained. The mixture was cooled to 120 °C and then diluted with 1480 mL of hexane. Upon addition of hexane, the mixture was further cooled to 67 °C. The mixture was maintained at this temperature for 2 h and then cooled to room temperature. The resulting clear solution was stored under a nitrogen atmosphere and used as obtained. Analysis of the solution showed a titanium concentration of 0.25 mol / L.

[0096] Catalyst preparation

[0097] In a 0.8-liter glass reactor equipped with baffles, a reflux condenser, and a stirrer, 424 ml of hexane and 160 ml of the complex from Example I were metered in. The stirrer was set to 1200 RPM. In a separate flask, 100 ml of a 50% dichloroethylaluminum (EADC) solution was added to 55 ml of hexane. The resulting EADC solution was metered into the reactor over 15 minutes using a peristaltic pump. The mixture was then refluxed for 2 hours. After cooling to ambient temperature, the resulting red / brown suspension was transferred to a glass P4 filter and the solids were separated. The solids were washed three times with 500 ml of hexane. The solids were absorbed in 0.5 L of hexane, and the resulting slurry was stored under nitrogen. The solids content was 64 g / ml. -1 .

[0098] Catalyst analysis results:

[0099] Ti 10.8 wt%; Mg 11.2 wt%; Al 5.0 wt%; CI 65 wt%; OEt 3.2 wt% and OFu 2.6 wt%.

[0100] Preparation of ethylene copolymers

[0101] Invention Embodiment 1

[0102] A continuous stirred tank reactor (CSTR) with a total volume of 20 liters and an operating volume of 15 liters was operated at 88 °C and a total pressure of 5.0 barg. To produce the first polymer fraction, a mixture of 750 g / h ethylene, 1.08 g / h hydrogen, and 2869 g / h hexane was added to the polymerization reactor. Additionally, catalyst 1, prepared as described above, was introduced into the reactor at the rate required to maintain a constant total pressure. No additional comonomers were introduced into the reactor. The reactor conditions are shown in Table 1.

[0103] The polymer slurry is discharged from the reactor and transferred to an adiabatic flash evaporator, with pressure controlled to achieve the desired H2 / C2 gas ratio in the second reactor. After this flash evaporation step, the polymer slurry is removed from the flash vessel and transferred to a second CSTR reactor having the same total volume and operating volume as the first CSTR reactor.

[0104] The second CSTR reactor was operated at 67 °C and a total pressure of 4.9 barg. A mixture of ethylene at a rate of 495 g / h, hexane at a rate of 6000 g / h, 1-hexene at a rate of 260 g / h, and nitrogen were introduced into the reactor to maintain a constant total pressure of 4.9 barg. The conditions in the second CSTR reactor are shown in Table 1.

[0105] The slurry discharged from the second CSTR reactor was transferred to a centrifugal decanter, where the polymer and hexane were separated.

[0106] The resulting polymer was then dried overnight under vacuum at 60°C. The dried polymer was stabilized using a mixture of calcium stearate, Irgafos 168, and Irganox 1010 at a weight ratio of 50 / 37.5 / 12.5 (3000 ppm) and subsequently extruded into pellets in a Coperion NT co-rotating twin-screw extruder system with an extruder throughput of 25.9 kg / h.

[0107] Invention Embodiment 2

[0108] Embodiment 2 is the same as Embodiment 1, except that the polymerization conditions and feed are as shown in Table 1.

[0109] Comparative Experiment 3

[0110] Comparative Experiment 3 is the same as Embodiment 1 of the Invention, except that:

[0111] - Use catalyst 2 instead of catalyst 1

[0112] - Polymerization conditions and feed are shown in Table 1.

[0113] - During the granulation of the polymer powder, pure carbon black is added in addition to the additives added in Example 1 of the invention.

[0114] Table 1

[0115]

[0116]

[0117] The various properties of ethylene-1-hexene copolymer granules of IE1, IE2 and CE3 are shown in Table 2. In addition, the properties of granules made from the following ethylene copolymers were measured, and the results are shown in Table 2.

[0118] CE4: A6060 00900, a commercial material (ethylene-1-butene copolymer) available from SABIC for PE100 pipe applications.

[0119] CE5: HE3490LS, a commercial material (ethylene-1-butene copolymer) available from Borealis for PE100 pipe applications.

[0120] CE6: Eltex TUB 124N6000, a commercial material (ethylene-1-hexene copolymer) available from Ineos for PE100 pipe applications.

[0121] Table 2

[0122]

[0123] *For CE3, the density was measured on pellets containing the same additives as IE1 and IE2 (without carbon black).

[0124] For CE5, the density measured on the pellets manufactured with the addition of carbon black is 961.8 kg / m³. 3 The density of the carbon black-free granules can be estimated to be approximately 950 kg / m³. 3 .

[0125] ***For CE6, the density measured on the granules manufactured with the addition of blue pigment is 953 kg / m³. 3 The particle density without blue pigment is estimated to be approximately 952 kg / m³. 3 .

[0126] It is understood that the ethylene copolymers (IE1 and IE2) according to the invention have a combination of good processability due to low viscosity (η300) during pipe extrusion, better surface appearance and better uniformity due to low η0.05, and very high impact strength at low temperatures.

[0127] In contrast, CE3, CE4 and CE5 have low impact strength at low temperatures.

[0128] It should also be noted that the ethylene compositions (IE1 and IE2) according to the invention have much lower viscosity than the embodiments of EP3647645 (η0.05 is 1039 to 1424 kPas and η300 is 1190 to 1753 Pas), thus providing better processability, surface appearance and uniformity.

[0129] It should also be noted that the ethylene compositions (IE1 and IE2) of the present invention have much lower viscosity than the examples of WO2020088987 (η0.05 is 935 to 1288 kPas and η300 is 1297 to 1476 Pas), thus providing better processability, surface appearance and uniformity.

[0130] In addition, polyethylene compositions of IE1 and CE3-CE6 were extruded into 32 mm SDR 11 pipes in a Reifenhauser S50×30D pipe extruder. The extrusion conditions are shown in Table 3.

[0131] Table 3

[0132] throughput (kg / h) 50-60 Pipeline velocity (m / min) 3.5 Cylinder section 1 (°C) 75 Cylinder section 2 (°C) 200 Cylindrical zone 3 (°C) 220 Cylinder section 4 (°C) 225 Cylinder section 5 (°C) 230 Cylindrical zone 6 (°C) 230 Cylinder section 7 (°C) 235 Cylindrical zone 8 (°C) 235 Cylinder section 9 (°C) 240

[0133] Pressure tests were performed on the pipeline using Type A end caps according to ISO 1167-1:2006. The results of the pressure tests are shown in Table 4.

[0134] Table 4

[0135] 13MPa, 20℃ (h) 1046 13MPa, 20℃ (h) 1300 13MPa, 20℃ (h) 1834 12.8 MPa, 20℃ (h) 5109 12.8 MPa, 20℃ (h) >5270 12.8 MPa, 20℃ (h) >5270 12.6 MPa, 20℃ (h) 34 12.6 MPa, 20℃ (h) 67 12.6 MPa, 20℃ (h) 47 12.4 MPa, 20℃ (h) 83 202 12.4 MPa, 20℃ (h) 109 328 12.4 MPa, 20℃ (h) 84 889 12.0 MPa, 20℃ (h) 201 315 12.0 MPa, 20℃ (h) 210 410 12.0 MPa, 20℃ (h) 300 266

[0136] Understandably, pipes made from the polyethylene composition (IE1) according to the present invention have a much higher pressure resistance than CE3, CE4, CE5 and CE6.

[0137] The properties mentioned in this article are measured as follows.

[0138] MFI

[0139] MFI is measured at 190°C under loads of 1.2 kg (MI1.2), 5 kg (MI5), or 21.6 kg (MI21.6) according to ISO 1133-1:2011.

[0140] density

[0141] The density of the polymer powder sample was measured in a TP200 Fontyne press according to ISO 17855-2 by preparing a 40×40×1.6 mm polymer test plate. The compression cycle was performed at a temperature set at 180°C and a contact pressure for 10 minutes. Cooling was carried out as follows: an initial time of 30 seconds without increasing the pressure, followed by increasing the pressure up to 200 kN, and maintaining the pressure level for the time required for the sample to reach 23°C at a cooling rate of 15 ± 2°C / min. The mass of the test plate was determined in air (XS104 Mettler Toledo analytical balance). Subsequently, the test plate was immersed in 4 liters of 100°C water (Toyo Seiki D-H100 automatic densitometer equipped with a WMR MX7LR-20 thermostatic bath) for 10 minutes, after which heating was turned off and the sample was cooled to room temperature. The density was determined as follows:

[0142]

[0143] in:

[0144] ρ s =Density of the test plate (g / cm³) 3 )

[0145] m s，空气 =Mass of the test plate in air (g)

[0146] ρ 水 = Density (g / cm3) of mineral water at the test temperature (23℃)

[0147] m s+nc，水 =Mass of the test plate and sedimentation plate in water (g)

[0148] m nc，水 =Mass of the settling plate trapped in the water (g)

[0149] Note: Since polyethylene has a lower density than water, a settling sheet is used to keep the test plate immersed.

[0150] The density of the polymer granule samples was measured by immersion method according to ISO 1183A.

[0151] Comonomer content

[0152] The sample was dissolved at 125 °C in C₂D₂Cl₄ containing DBPC (2,6-di-tert-butyl-p-cresol) as a stabilizer. Recordings were performed on a Bruker Avance 500 NMR spectrometer equipped with a 10 mm cryogenically cooled probe tip for operation at 125 °C. 13 C NMR spectra were processed using Bruker Topsin 3.6.

[0153] Dynamic mechanical properties (viscosity η) :

[0154] The viscosity at each shear rate was calculated by fitting the flow curves generated by an oscillatory reometer according to ISO 6721-10 at 190 °C on parallel plates with a diameter of 25 mm and a gap of 1.2 mm between 0.01 and 100 rad / s, using a modified Carreau-Yasuda model. The viscosity is expressed by the following equation:

[0155]

[0156] in

[0157] η is the viscosity in Pa·s.

[0158] η0 is the zero-shear viscosity (Pa·s).

[0159] 'a' is the rheometry width parameter.

[0160] n is a power-law constant, which is set to 0 in this case (to define the slope of the high shear rate region).

[0161] γ is the shear rate (1 / s).

[0162] λ is the relaxation time.

[0163] η 300 The viscosity values ​​are in Pa·s at a shear rate of 300 rad / s and 190 °C, calculated as previously fitted to the flow curve data [1], which were generated by oscillatory rheological determination at 0.01 and 100 rad / s on a parallel plate with a diameter of 25 mm and a gap of 1.2 mm at 190 °C according to ISO 6721-10.

[0164] η 0.05 The viscosity values ​​are in Pa·s at 190°C and a shear rate of 0.05 rad / s, calculated as previously fitted to the flow curve data [1], which were generated by oscillatory rheological determination at 190°C between 0.01 and 100 rad / s on parallel plates with a diameter of 25 mm and a gap of 1.2 mm, according to ISO 6721-10.

[0165] To facilitate model fitting, the power-law constant is kept constant, which is zero in this case. The importance and interpretation of the Carreau-Yasuda model, as well as details of the derived parameters, can be found in the following references: CA Hieber and H.H. Chiang, Rheol Acta, 28, 321 (1989); CA Hieber and HH Chiang, Polym. Eng. Sci., 32, 931 (1992); and RB Bird, R. C. Armstrong and O. Hasseger, Dynamics of Polymeric Liquids, Vol. 1, Fluid Mechanics, 2nd Edition, John Wiley & Sons (1987), each of which is incorporated herein by reference in its entirety.

[0166] Molecular weight distribution (MWD) and moments of MWD

[0167] Mw, Mn, and Mz are measured according to ASTM D6474-12 (Standard Test Method for Determination of Molecular Weight Distribution and Molecular Weight Mean of Polyolefins by High-Temperature Gel Permeation Chromatography). Mw represents weight-average molecular weight, and Mn represents number-average molecular weight. Mz represents z-average molecular weight.

[0168] MWD and SCB as a function of molecular weight were determined at 160 °C using a PolymerChar GPC-IR system (PolymerChar SA, Spain) equipped with an IR5 MCT sensor and a PolymerChar viscometer. Three columns (Polymer Laboratories 13 μm PLgel Olexis, 300 × 7.5 mm) were used in series for GPC separation. 1,2,4-trichlorobenzene stabilized with 1 g / L butylated hydroxytoluene (also known as 2,6-di-tert-butyl-4-methylphenol or BHT) was used as the eluent at a flow rate of 1 mL / min. The sample concentration was approximately 0.7 mg / mL, and the injection volume was 300 μL. Molar mass was determined based on general GPC principles using PE narrow and wide standards (ranging from 0.5 to 2800 kg / mol, Mw / Mn⁻⁴ to 15) combined with known Mark Houwink constants (α = 0.725 and log K = -3.721) of the PE calibrator.

[0169] Yield stress:

[0170] According to ISO 527-1, on type 1B strips, at 23°C, the yield stress was measured by a modulus test at 1 mm / min and a tensile test at 50 mm / min, using the average result of 5 samples.

[0171] strain hardening modulus

[0172] Strain hardening was determined according to ISO 18488.

[0173] Impact resistance

[0174] Impact resistance was measured according to ISO 179-1 / 1eA, non-instrumental testing, at -30°C, 0°C, and 23°C, using the Charpy method on specimens measuring 80×10×4mm with an A-notch. The result is the average of five tested specimens. The airflow direction was along the edge. Specimens were prepared by compression molding at a molding temperature of 180°C, a molding cooling rate of 15°C / min, and a sheet thickness of 4mm, according to ISO 17855-2. The final specimens were prepared by machining from the compression-molded sheet.

[0175] Internal pressure test

[0176] According to ISO 1167-1:2006, IPT testing is performed on a 32mm SDR11 pipe using a type A end cap at 20°C.

Claims

1. A multimodal ethylene copolymer, comprising the following: 55 to 80% by weight of ethylene homopolymer component A, and Component B is an ethylene copolymer of 20 to 45% by weight of ethylene and C3-C20 olefin comonomers. The component A thereon has: According to ISO 1133-1:2011, the melt flow index is 80 to 400 dg / min, measured at 190°C and 1.2 kg. At least 968 kg / m 3 density, and The multimodal ethylene copolymer has the following characteristics: According to ISO 1133-1:2011, the melt flow index ranges from 0.05 to 0.3 dg / min, measured at 190°C and 5 kg. 956 to 962 kg / m 3 density, Comonomer content of 0.03 to 0.30 mol%, The viscosity values ​​η0.05 at 190 °C and a shear rate of 0.05 rad / s, ranging from 200 to 1000 kPa·s, are... The viscosity value η300 is between 700 and 1500 Pa·s at a temperature of 190°C and a shear rate of 300 rad / s.

2. The multi-peak ethylene copolymer according to claim 1, wherein the C3-C20 olefin comonomer is selected from C3-10 α-olefin.

3. The multimodal ethylene copolymer according to claim 2, wherein the C3-C20 olefin comonomer is selected from propylene, 1-butene, 1-hexene and 1-octene.

4. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the ethylene copolymer component B is an ethylene copolymer of ethylene and 1-hexene.

5. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the multimodal ethylene copolymer has a melt flow index of 5 to 15 dg / min as measured according to ISO 1133-1:2011 at 190°C and 21.6 kg.

6. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the multimodal ethylene copolymer has a content of 958 to 960 kg / m³. 3 The density.

7. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the multimodal ethylene copolymer has a comonomer content of 0.10 to 0.20 mol%.

8. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the multimodal ethylene copolymer has a Charpy impact strength of at least 20 kJ / m² as determined according to ISO 179-1 / 1eA at -30°C.

9. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the total amount of components A and B relative to the multimodal ethylene copolymer is at least 80% by weight.

10. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the total amount of components A and B relative to the multimodal ethylene copolymer is at least 90% by weight.

11. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the total amount of components A and B relative to the multimodal ethylene copolymer is at least 95% by weight.

12. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the total amount of components A and B relative to the multimodal ethylene copolymer is at least 98% by weight.

13. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the total amount of components A and B relative to the multimodal ethylene copolymer is at least 99% by weight.

14. The multimodal ethylene copolymer according to any one of claims 1-3, wherein the total amount of components A and B relative to the multimodal ethylene copolymer is 100 by weight.

15. A method for preparing a multimodal ethylene copolymer according to any one of claims 1-14, comprising preparing component A and subsequently preparing component B in the presence of component A, wherein components A and B are each prepared by slurry polymerization in the presence of a Ziegler-Natta catalyst system.

16. A method for preparing a multi-peak ethylene copolymer according to any one of claims 1-14, comprising a multi-step slurry polymerization process using a cascade reactor in the presence of a Ziegler-Natta catalyst system.

17. The method according to claim 15 or 16, wherein the catalyst system comprises: (I) The solid reaction products obtained by reactions a) and b). a) A hydrocarbon solution containing 1) and 2), 1) Organic oxygen-containing magnesium compounds or halogenated magnesium compounds, and 2) Organic oxygen-containing titanium compounds, and b) Having the formula AlR n X 3-n Aluminum halides, where R is a hydrocarbon moiety containing 1-10 carbon atoms, X is a halogen and 0 < n < 3, and (II) An aluminum compound having the formula AlR3, wherein R is a hydrocarbon structural moiety containing 1 to 10 carbon atoms.

18. A composition comprising the multimodal ethylene copolymer and the additive according to any one of claims 1-14.

19. The composition of claim 18, wherein the amount of the multimodal ethylene copolymer is 90 to 99.9% by weight of the composition.

20. The composition of claim 19, wherein the amount of the multimodal ethylene copolymer is at least 95% by weight of the composition.

21. The composition of claim 19, wherein the amount of the multimodal ethylene copolymer is at least 98% by weight of the composition.

22. The composition of claim 19, wherein the amount of the multimodal ethylene copolymer is at least 99% by weight of the composition.

23. An article comprising a multimodal ethylene copolymer according to any one of claims 1-14 or a composition according to any one of claims 18-22.

24. The article of claim 23, wherein the article is an extruded article.

25. The article of claim 23, wherein the article is a pipe.

26. The pipe of claim 25, wherein the pipe has a pressure resistance of at least 1000 hours at 20°C under circumferential stress of 13.0 MPa using a type A end cap, as determined according to ISO 1167-1:2006, and / or a pressure resistance of at least 5000 hours at 20°C under circumferential stress of 12.8 MPa using a type A end cap, as determined according to ISO 1167-1:2006.

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