Polyethylene composition for blow molding having high swell ratio, impact resistance and tensile modulus

Abstract

A polyethylene composition, particularly suitable for the production of blow-moulded hollow articles, having the following characteristics: 1) a density from 0.957 to 0.968 g / cm 3 3) a MIF from 41 to 60 g / 10 min; 4) a long chain branching index LCBI equal to or greater than 0.45; 5) a (η 0.02 / 1000) / LCBI ratio from 45 to 75.

Description

Technical Field

[0001] This disclosure relates to a polyethylene composition suitable for the blow molding production of small articles, particularly bottles. Background Technology

[0002] Examples of prior art compositions suitable for the stated use are disclosed in WO2009003627, WO2014134193, WO2014206854, WO2018095700 and WO2021028159.

[0003] It has been found that by appropriately selecting the molecular structure and rheological behavior of the composition, exceptionally high swelling ratios, impact resistance, and tensile modulus can be achieved in combination with an extremely smooth surface of the final product, with reduced gel content and high melt flow index values, which provides improved processability. Summary of the Invention

[0004] Therefore, this disclosure provides a polyethylene composition having the following characteristics:

[0005] 1) From 0.957 to 0.968 g / cm³ 3 The preferred concentration is between 0.958 and 0.968 g / cm³. 3 More preferably, from 0.959 to 0.965 g / cm³. 3 The density was determined at 23°C according to ISO 1183-1:2012;

[0006] 2) A MIF / MIP ratio of 12 to 30, preferably 15 to 25, and especially 15 to 23, wherein MIF is the melt flow index at 190°C and a load of 21.60 kg, and MIP is the melt flow index at 190°C and a load of 5 kg, both determined according to ISO 1133-12012-03;

[0007] 3) MIF from 41 to 60g / 10 minutes, preferably from 43 to 55g / 10 minutes, more preferably from 45 to 55g / 10 minutes;

[0008] 4) A long chain branching index (LCBI) equal to or greater than 0.45, preferably equal to or greater than 0.50, where the LCBI is the measured mean square radius of gyration R measured by GPC-MALLS. g The ratio of the radius of gyration of linear PE with the same molecular weight;

[0009] 5) In η 0.02 Dividing by 1000 and LCBI, from 45 to 75, preferably from 50 to 70 (η) 0.02 / 1000) / LCBI ratio. Attached Figure Description

[0010] These and other features, aspects, and advantages of this disclosure will become more readily understood with reference to the following description, the appended claims, and the accompanying drawings, wherein:

[0011] The accompanying figure is an illustrative embodiment of a simplified process flow diagram of two gas-phase reactors connected in series, which are suitable for producing various embodiments of the polyethylene compositions disclosed herein according to various embodiments of the ethylene polymerization process disclosed herein.

[0012] It should be understood that the various embodiments are not limited to the arrangements and tools shown in the accompanying drawings. Detailed Implementation

[0013] The term "polyethylene composition" is intended to cover alternatives to single ethylene polymers and ethylene polymer compositions, particularly compositions of two or more ethylene polymer components, preferably having different molecular weights, and such compositions are also referred to in the relevant field as "bimodal" or "multimodal" polymers.

[0014] Typically, this polyethylene composition consists of or includes one or more ethylene copolymers.

[0015] All features defined herein, including the previously defined features 1) through 5), relate to the ethylene polymer or ethylene polymer composition. Adding other components, such as additives commonly used in the art, may modify one or more of these features.

[0016] The MIF / MIP ratio provides a rheological measurement of molecular weight distribution.

[0017] Another measurement of molecular weight distribution is provided by the ratio Mw / Mn, where Mw is the weight-average molecular weight and Mn is the number-average molecular weight, measured by GPC (gel permeation chromatography), as explained in the examples.

[0018] The preferred Mw / Mn value of this polyethylene composition ranges from 25 to 45, particularly from 30 to 40.

[0019] The preferred range for LCBI values ​​is:

[0020] -From 0.45 to 0.65; or

[0021] -From 0.45 to 0.60; or

[0022] -From 0.50 to 0.65; or

[0023] -From 0.50 to 0.60.

[0024] In addition, this polyethylene composition preferably has at least one of the following additional features.

[0025] - η from 25,000 to 38,000 Pa·s, preferably from 25,000 to 34,000 Pa·s 0.02 , where η 0.02 It is the complex shear viscosity at an angular frequency of 0.02 rad / s, measured in a plate-to-plate rotational rheometer at 190°C using dynamic oscillatory shear.

[0026] - The content of comonomers is equal to or less than 0.3% by weight relative to the total weight of the composition, particularly from 0.05% to 0.3% by weight;

[0027] - Mw equal to or greater than 230,000 g / mol, especially from 230,000 to 400,000 g / mol;

[0028] - Mz equal to or greater than 1,000,000 g / mol, particularly from 1,000,000 g / mol to 2,500,000 g / mol, where Mz is the z-average molecular weight as measured by GPC;

[0029] - Mz / Mw equal to or greater than 5.8, preferably equal to or greater than 6.3, more preferably equal to or greater than 6.4, most preferably equal to or greater than 6.5, especially from 5.8 to 9, or from 6.3 to 9, or from 6.4 to 9, or from 6.5 to 9;

[0030] - Equal to or less than 0.8 g / 10 min, especially from 0.8 to 0.1 g / 10 min, where MIE is the melt flow index at 190 °C and 2.16 kg load as determined according to ISO 1133-12012-03;

[0031] - MIP from 1 to 10g / 10 minutes, more preferably from 1.5 to 8g / 10 minutes, or from 2 to 8g / 10 minutes;

[0032] - Equal to or greater than 1, preferably equal to or greater than 1.5, especially ER from 1 to 8 or from 1.5 to 8;

[0033] - ET equal to or less than 25, especially ET from 3 to 25 or from 7 to 25;

[0034] - The HMWcopo index ranges from 0.1 to 3, especially from 0.1 to 2;

[0035] The HMWcopo index is determined according to the following formula:

[0036] HMWcopo=(η 0.02 xt maxDSC ) / (10^5)

[0037] Where tmaxDSC is the time (in minutes) required to reach the maximum heat flux (in mW) of crystallization at 124°C in a differential scanning calorimeter DSC under static conditions in isothermal mode (the time to reach the maximum crystallization rate is equivalent to the crystallization half-life t1 / 2); LCBI is the ratio of the measured mean square radius of gyration Rg to the mean square radius of gyration of linear PE with the same molecular weight when the molecular weight is 1,000,000 g / mol, as measured by GPC-MALLS.

[0038] One or more comonomers present in ethylene copolymers are typically selected from olefins having the formula CH2=CHR, where R is a straight-chain or branched alkyl radical having 1 to 10 carbon atoms.

[0039] Specific examples are propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, and decene-1. A particularly preferred comonomer is hexene-1.

[0040] In particular, in a preferred embodiment, the composition comprises:

[0041] A) 30 to 70% by weight, preferably 40 to 60% by weight, of an ethylene homopolymer or copolymer (homogene is preferred), wherein the ethylene homopolymer or copolymer has a concentration equal to or greater than 0.960 g / cm³. 3 The density and 65g / 10min or higher, preferably 75g / 10min or higher, especially MIE from 65 to 100g / 10min or 75 to 100g / 10min;

[0042] B) 30 to 70% by weight, preferably 40 to 60% by weight, of an ethylene copolymer having a MIE value lower than that of A), preferably lower than 0.5 g / 10 min.

[0043] The percentages above are given relative to the total weight of A) + B).

[0044] Preferably, the difference between the density value of component A) and the density value of the composition is equal to or less than 15 kg / m³. 3 Especially from 15 to 5 kg / m 3 .

[0045] As previously stated, this polyethylene composition can be advantageously used in the production of blow-molded articles, such as those with capacities from 200 to 5000 cm³. 3 Blow-molded containers, especially blow-molded dairy and beverage bottles.

[0046] In fact, it is preferably characterized by the following properties.

[0047] - A swelling ratio higher than 180%, especially 185% or higher, with an upper limit of 220% preferred in all cases;

[0048] -70kJ / m at -30℃ 2 Or even higher, especially from 70 to 100 kJ / m 2 AZK;

[0049] -1400 MPa or higher, more preferably 1470 MPa or higher, especially tensile modulus (E-modulus) measured according to ISO 527-2 / 1B / 50 from 1400 to 1800 MPa or from 1470 to 1800 MPa;

[0050] - Gel volume per m³ with a gel diameter greater than 700 μm 2 Less than 1;

[0051] - Gel volume per m³ with a gel diameter greater than 450 μm 2 Less than 2.5.

[0052] Details of the testing methods are given in the examples.

[0053] High tensile modulus values ​​are required to withstand deformation during the filling, closure, and stacking of blow-molded containers.

[0054] The blow molding process is typically carried out as follows: first, a polyethylene composition is plasticized in an extruder at a temperature ranging from 180 to 250°C, and then it is extruded through a die into a blow mold, where it is cooled.

[0055] While there are no necessary restrictions in principle on the polymerization process and the type of catalyst used, it has been found that this polyethylene composition can be prepared by gas-phase polymerization in the presence of a Ziegler-Natta catalyst.

[0056] Ziegler-Natta catalysts comprise reaction products of organometallic compounds from Groups 1, 2, or 13 of the periodic table and transition metal compounds (new symbols) from Groups 4 to 10 of the periodic table. Specifically, the transition metal compounds can be selected from compounds of Ti, V, Zr, Cr, and Hf, and are preferably supported on MgCl2.

[0057] Particularly preferred catalysts comprise the reaction products of organometallic compounds of Groups 1, 2, or 13 of the periodic table and solid catalyst components including Ti compounds supported on MgCl2.

[0058] The preferred organometallic compounds are organo-Al compounds.

[0059] Therefore, in a preferred embodiment, this polyethylene composition can be obtained by using a Ziegler-Natta polymerization catalyst, more preferably a Ziegler-Natta catalyst supported on MgCl2, and even more preferably a Ziegler-Natta catalyst comprising the following reaction products:

[0060] a) A solid catalyst component comprising a Ti compound supported on MgCl2 and an electron donor compound ED;

[0061] b) Organic-Al compounds; and optionally

[0062] c) External electron donor compound ED 外 .

[0063] Preferably, in component a), the ED / Ti molar ratio ranges from 1.5 to 3.5, and the Mg / Ti molar ratio is higher than 5.5, particularly from 6 to 80.

[0064] Suitable titanium compounds are tetrahalides or of the formula TiX n (OR 1 ) 4-n The compound wherein 0 ≤ n ≤ 3, X is a halogen, preferably chlorine, and R 1 It is C1 to C 10 Hydrocarbon group. Titanium tetrachloride is a preferred compound.

[0065] ED compounds are typically selected from esters of alcohols, ketones, amines, amides, nitriles, alkoxysilanes, aliphatic ethers, and aliphatic carboxylic acids.

[0066] Preferably, the ED compound is selected from amides, esters, and alkoxysilanes.

[0067] Excellent results have been obtained using esters, which are therefore particularly preferred as ED compounds. Specific examples of esters are alkyl esters of C1 to C20 aliphatic carboxylic acids, and especially C1 to C8 alkyl esters of aliphatic monocarboxylic acids, such as ethyl acetate, methyl formate, ethyl formate, methyl acetate, propyl acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate. Furthermore, aliphatic ethers are preferred, and especially C2 to C20 aliphatic ethers, such as tetrahydrofuran (THF) or dioxane.

[0068] In the solid catalyst component, MgCl2 is a basic support, even if a small amount of additional support can be used. MgCl2 can be used as is or obtained from Mg compounds used as precursors, which can be converted to MgCl2 by reacting with halogenated compounds. Particularly preferred is the use of the active form of MgCl2, widely known from patent literature, as the support for Ziegler-Natta catalysts. Patents USP 4,298,718 and USP 4,495,338 first describe the use of these compounds in Ziegler-Natta catalysis. It is known from these patents that the active form of magnesium dihalides used as a support or co-support in catalyst components for olefin polymerization is characterized by X-ray spectroscopy, wherein the strongest diffraction line appearing in the ASTM card reference of the spectrum of the inactive halide is weakened in intensity and broadened. In the X-ray spectrum of the preferred active form of magnesium dihalides, the intensity of the strongest spectral line is reduced and replaced by a halo whose maximum intensity is shifted at a lower angle relative to the strongest spectral line.

[0069] A catalyst is particularly suitable for preparing the polyethylene compositions of the present invention, wherein the solid catalyst component a) is obtained by first contacting a titanium compound with MgCl2 or a precursor Mg compound, optionally in the presence of an inert medium, thereby preparing an intermediate product a') containing a titanium compound supported on MgCl2, and then, optionally in the presence of an inert medium, contacting the intermediate product a') with an ED compound, which is added to the reaction mixture alone or in a mixture with other compounds, wherein the ED compound represents the major component.

[0070] For the term "major component," we mean that the ED compound must be the major component in molar terms, relative to other possible compounds excluded from the inert solvent or diluent used to treat the contact mixture. The ED-treated product can then be washed with a suitable solvent to recover the final product. Treatment with the desired ED compound can be repeated once or multiple times if necessary.

[0071] As previously mentioned, MgCl2 precursors can be used as the necessary Mg compounds for initiation. This can be selected, for example, from Mg compounds of the formula MgR'2, where the R' group can be independently an optionally substituted C1 to C20 hydrocarbon group, an OR group, an OCOR group, or chlorine, wherein R is an optionally substituted C1 to C20 hydrocarbon group, the obvious condition being that the R' group is not simultaneously chlorine. Also suitable as precursors are Lewis adducts between MgCl2 and a suitable Lewis base. A particularly preferred class consists of MgCl2(R"OH) mThe adduct is composed of a C1 to C20 hydrocarbon group, preferably a C1 to C10 alkyl group, and m is from 0.1 to 6, preferably from 0.5 to 3, and more preferably from 0.5 to 2. This type of adduct is typically obtained by mixing an alcohol and MgCl2 in the presence of an inert hydrocarbon immiscible with the adduct, and operating under stirring at the melting temperature of the adduct (100 to 130 °C). The emulsion is then rapidly quenched, thereby solidifying the adduct into spherical particles. Representative methods for preparing these spherical adducts are reported, for example, in USP 4,469,648, USP 4,399,054, and WO98 / 44009. Another available method for spheroidization is spray cooling, for example, as described in USP 5,100,849 and 4,829,034.

[0072] Of particular interest is MgCl2·(EtOH) m An adduct, wherein m is from 0.15 to 1.7, is obtained by thermally de-alcoholizing an adduct with a high alcohol content in a nitrogen stream at a temperature between 50 and 150 °C until the alcohol content is reduced to the aforementioned value. This type of process is described in EP 395083.

[0073] De-alcoholization can also be carried out chemically by contacting the adduct with a compound that can react with an alcohol group.

[0074] Typically, these dealcohol adducts are also characterized by a porosity (measured by the mercury method) ranging from 0.15 to 2.5 cm⁻¹ due to pores with a radius of up to 0.1 μm. 3 / g, preferably from 0.25 to 1.5cm 3 / g.

[0075] These adducts, preferably titanium tetrachloride, react with the aforementioned TiX. n (OR 1 ) 4-n The reaction of the compound (or a possible mixture thereof) with the Ti compound can be carried out by suspending the adduct in TiCl4 (usually cold). The mixture is heated to a temperature ranging from 80 to 130 °C and held at that temperature for 0.5 to 2 hours. Treatment with the titanium compound can be carried out once or multiple times. It is preferred to repeat twice. It can also be carried out in the presence of the aforementioned electron donor compound. At the end of the process, the solid is recovered by separating the suspension by conventional methods such as sedimentation and removal of liquid, filtration, centrifugation, and can be washed with a solvent. Although washing is usually carried out with inert hydrocarbon liquids, solvents with greater polarity (having, for example, a higher dielectric constant) such as halogenated hydrocarbons can also be used.

[0076] As described above, the intermediate product is then contacted with the ED compound under conditions that allow an effective amount of donor to be immobilized on the solid. Due to the high versatility of this method, the amount of donor used varies widely. As an example, it can be used at a molar ratio ranging from 0.5 to 20, and preferably from 1 to 10, relative to the Ti content in the intermediate product. Although not strictly required, the contact is typically carried out in a liquid medium such as liquid hydrocarbons. The temperature at which the contact occurs can vary depending on the nature of the reagent. It typically includes a range from -10°C to 150°C, and preferably from 0°C to 120°C. Temperatures that would cause decomposition or degradation of any particular reagent should be avoided, even if the temperature falls within a generally suitable range. The treatment time can also vary depending on other conditions such as the nature of the reagent, temperature, concentration, etc. As a general indication, this contact step can last from 10 minutes to 10 hours, more often from 0.5 to 5 hours. If desired, this step can be repeated once or multiple times to further increase the final donor content. At the end of this step, the solid is recovered by separating the suspension via conventional methods (such as sedimentation and liquid removal, filtration, centrifugation) and can be washed with a solvent. Although washing is usually done with inert hydrocarbon liquids, solvents with greater polarity (having, for example, a higher dielectric constant) such as halogenated hydrocarbons or oxidized hydrocarbons can also be used.

[0077] As previously mentioned, according to known methods, the solid catalyst component is converted into a catalyst for olefin polymerization by reacting it with organometallic compounds of Groups 1, 2 or 13 of the periodic table, particularly with alkyl Al compounds.

[0078] The alkyl-Al compound is preferably selected from trialkylaluminum compounds, such as, for example, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum. Alkylaluminum halides, alkylaluminum hydrides, or alkylaluminum sesquichlorides such as AlEt2Cl and Al2Et3Cl3 can also be used, optionally mixed with the trialkylaluminum compound.

[0079] ED, an external electron donor compound optionally used in the preparation of the Ziegler-Natta catalyst, 外 It may be equal to or different from the ED used in solid catalyst component a). It is preferably selected from the group consisting of ethers, esters, amines, ketones, nitriles, silanes and mixtures thereof. In particular, it may be advantageously selected from C2 to C20 aliphatic ethers, and especially preferably cyclic ethers having 3 to 5 carbon atoms, such as tetrahydrofuran and dioxane.

[0080] The catalyst can be prepolymerized using known techniques to produce a reduced amount of polyolefin, preferably polypropylene or polyethylene. Prepolymerization can be carried out prior to the addition of the electron donor compound ED, thus by prepolymerizing the intermediate a'). Alternatively, the solid catalyst component a') can be prepolymerized.

[0081] The amount of prepolymer that can be produced per gram of intermediate product a') or component a) is up to 500g. Preferably, it is 0.5 to 20g per gram of intermediate product a').

[0082] Prepolymerization can be carried out using suitable cocatalysts such as organoaluminum compounds, which can also be used in combination with external electron donor compounds as discussed above.

[0083] It can be carried out in the liquid or gas phase at temperatures ranging from 0 to 80°C, preferably from 5 to 70°C.

[0084] The intermediate product a') is particularly preferred to be subjected to a catalyst that prepolymerizes as described above.

[0085] It has been found that, by using the above-described polymerization catalyst, the polyethylene composition of the present invention can be prepared in any order in a process including the following steps:

[0086] a) In a gas-phase reactor, ethylene is optionally polymerized with one or more comonomers in the presence of hydrogen;

[0087] b) In another gas-phase reactor, in the presence of hydrogen in an amount less than that in step a), copolymerize ethylene with one or more comonomers;

[0088] In at least one of the gas-phase reactors, the grown polymer particles flow upward through a first polymerization zone (riser tube) under rapid fluidization or conveying conditions, leave the riser tube and enter a second polymerization zone (downstream tube), and flow downward through the second polymerization zone under gravity, leave the downstream tube and be reintroduced into the riser tube, thereby establishing a polymer cycle between the two polymerization zones.

[0089] In the first polymerization zone (riser), rapid fluidization conditions are established by feeding a gas mixture comprising one or more olefins (ethylene and comonomers) at a rate higher than the conveying speed of the polymer particles. The velocity of the gas mixture is preferably between 0.5 and 15 m / s, more preferably between 0.8 and 5 m / s. The terms "conveying speed" and "rapid fluidization conditions" are well known in the art; for their definitions, see, for example, D. Geldart, Gas Fluidisation Technology, pp. 155 et seq., J. Wiley & Sons Ltd., 1986.

[0090] In the second polymerization zone (downcomer), polymer particles flow in a densified form under the influence of gravity, thereby achieving a high solids density (mass of polymer per reactor volume), which is close to the bulk density of the polymer.

[0091] In other words, the polymer flows vertically downward through the downcomer in a piston flow (fill flow mode), so that only a small amount of gas is entrained between the polymer particles.

[0092] This type of process allows for the production of ethylene polymers with lower molecular weights from step a) than the ethylene copolymers obtained from step b).

[0093] Preferably, ethylene copolymerization is carried out upstream of the ethylene copolymerization to produce a relatively low molecular weight ethylene copolymer (step a). For this purpose, in step a), a gaseous mixture comprising ethylene, hydrogen, comonomers, and an inert gas is fed into a first gas-phase reactor, preferably a gas-phase fluidized bed reactor. Polymerization is carried out in the presence of the aforementioned Ziegler-Natta catalyst.

[0094] The hydrogen feed rate depends on the specific catalyst used and is in any case suitable for obtaining an ethylene polymer with a melt flow index (MIE) of 65 g / 10 min or higher in step a). To obtain the above MIE range, in step a), the hydrogen / ethylene molar ratio is indicated as from 1 to 5, and the amount of ethylene monomer is from 2 to 20% by volume, preferably from 5 to 15% by volume, based on the total volume of gases present in the polymerization reactor. The remainder of the feed mixture is represented by an inert gas and one or more comonomers (if any). The inert gas necessary to dissipate the heat generated by the polymerization reaction is conveniently selected from nitrogen or saturated hydrocarbons, most preferably propane.

[0095] The operating temperature in the reactor of step a) is selected between 50 and 120°C, preferably between 65 and 100°C, while the operating pressure is between 0.5 and 10 MPa, preferably between 2.0 and 3.5 MPa.

[0096] In a preferred embodiment, the ethylene polymer obtained in step a) accounts for 30 to 70% by weight of the total ethylene polymer produced throughout the process (i.e., in the first and second reactors connected in series).

[0097] The ethylene polymer and entrained gas from step a) are then passed through a solid / gas separation step to prevent the gaseous mixture from the first polymerization reactor from entering the reactor of step b) (the second gas-phase polymerization reactor). The gaseous mixture can be recycled back to the first polymerization reactor while the separated ethylene polymer is fed into the reactor of step b). A suitable point for feeding the polymer into the second reactor is at the connection between the downcomer and riser, where the solids concentration is particularly low so that the flow conditions are not negatively affected.

[0098] The operating temperature in step b) is in the range of 65 to 95°C, and the pressure is in the range of 1.5 to 4.0 MPa. The second gas-phase reactor is designed to produce relatively high molecular weight ethylene copolymers by copolymerizing ethylene with one or more comonomers. Furthermore, to broaden the molecular weight distribution of the final ethylene polymer, the reactor in step b) can be conveniently operated by establishing different conditions for monomer and hydrogen concentrations in the riser and downcomer.

[0099] Therefore, in step b), the entrainment of polymer particles and the gas mixture from the riser can be partially or completely prevented from entering the downcomer, thereby obtaining two distinct gas composition zones. This can be achieved by feeding a gas and / or liquid mixture into the downcomer through a line positioned at a suitable point in the downcomer, preferably above it. The gas and / or liquid mixture should have a suitable composition different from the gas mixture present in the riser. The flow of the gas and / or liquid mixture can be regulated to generate an upward gas flow countercurrent to the flow of the polymer particles, particularly at its top, acting as a barrier against the gas mixture entrained in the polymer particles from the riser. In particular, it is advantageous to feed a mixture with a low hydrogen content to produce a higher molecular weight polymer fraction in the downcomer. One or more comonomers can optionally be fed into the downcomer of step b) along with ethylene, propane, or other inert gases.

[0100] The hydrogen / ethylene molar ratio in the downcomer of step b) can be selected over a wide range, indicatively between 0.01 and 0.2, with an ethylene concentration ranging from 0.5 to 15% by volume, preferably from 0.5 to 10% by volume, and a comonomer concentration ranging from 0.01 to 0.5% by volume, based on the total volume of gas present in the downcomer. The remainder is propane or a similar inert gas. Due to the very low molar concentration of hydrogen in the downcomer, a relatively high amount of comonomer can be bonded to the high molecular weight polyethylene fraction by implementing this process.

[0101] The polymer particles from the downcomer are reintroduced into the riser of step b).

[0102] Since the polymer particles remain reactive and no more comonomers are fed into the riser, the concentration of the comonomer decreases to the range of 0.005 to 0.3 vol% based on the total volume of gas present in the riser. In practice, the comonomer content is controlled to obtain the desired density of the final polyethylene. In the riser of step b), the hydrogen / ethylene molar ratio is in the range of 0.05 to 1, and the ethylene concentration is between 5 and 20 vol% based on the total volume of gas present in the riser. The remainder is propane or other inert gases.

[0103] Further details regarding the above polymerization process are provided in WO2005019280.

[0104] Example

[0105] The various embodiments, compositions, and methods provided herein, their practices, and advantages are disclosed in the following examples. These examples are merely illustrative and are not intended to limit the scope of the appended claims in any way.

[0106] The following analytical methods are used to characterize polymer compositions.

[0107] density

[0108] Determined at 23°C according to ISO 1183-1:2012.

[0109] Complex shear viscosity η 0.02 (eta(0.02))ER and ET

[0110] The following measurements were taken at an angular frequency of 0.02 rad / s and at 190°C.

[0111] The sample was melt-pressed at 200°C and 200 bar for 4 minutes to form a 1 mm thick plate. A 25 mm diameter disc sample was punched and inserted into a rheometer preheated at 190°C. Any commercially available rotational rheometer can be used for measurement. Here, an Anton Paar MCR301 with a plate-to-plate geometry was used. A so-called frequency sweep was performed at T = 190°C with a constant strain amplitude of 5% (after annealing the sample at the measurement temperature for 4 minutes), measuring and analyzing the stress response of the material in the range of excitation frequency ω from 628 to 0.02 rad / s. Standardized basic software was used to calculate the rheological properties, i.e., storage modulus G', loss modulus G”, phase hysteresis δ (= arctangent(G” / G')), and complex viscosity η*, as a function of the applied frequency, i.e., η*(ω)=[G'(ω)] 2 +G”(ω) 2 ] 1 / 2 / ω. The latter, at an applied frequency ω of 0.02 rad / s, has a value of η. 0.02 .

[0112] ER was determined by the following method: R. Shroff and H. Mavridis, “New Measures of Polydispersity from Rheological Data on Polymer Melts,” *Journal of Applied Polymer Science*, 57(1995)1605 (see also column 10, lines 20–30 of U.S. Patent No. 5,534,472). Calculated from:

[0113] ER = (1.781 * 10 -3 )*G'

[0114] The value of G” = 5,000 dyn / cm 2 .

[0115] As those skilled in the art will recognize, when the minimum G” value is greater than 5,000 dyn / cm 2 In this case, the determination of ER involves extrapolation. The calculated ER value will then depend on the nonlinearity in log G' versus log G”. The temperature, plate diameter, and frequency range are chosen such that the lowest G” value is close to or less than 5,000 dynes / cm within the resolution of the rheometer. 2 .

[0116] ET is also determined by the following method: R. Shroff and H. Mavridis, “A new measure of polydispersity from polymer melt rheological data,” Journal of Applied Polymer Science, 57 (1995) 1605-1626. ET is a highly sensitive constant describing the polydispersity of polymers at the very high molecular weight end and / or describing an extremely broad molecular weight distribution. The higher the ET, the broader the rheological distribution of the polymer resin.

[0117] Calculated from:

[0118] ET = C2 / G * attanδ = C3

[0119] in:

[0120] G*=[(G') 2 +(G”) 2 ] 1 / 2 ;

[0121] tanδ = G” / G';

[0122] C2 = 10 6 dyn / cm 2 And C3 = 1.5.

[0123] HMWcopo Index

[0124] To quantify the crystallinity and processability potential of polymers, the HMWcopo (high molecular weight copolymer) index is used, which is defined by the following formula:

[0125] HMWcopo=(η 0.02 xt maxDSC ) / (10^5)

[0126] It decreases with increasing polymer processability (low melt viscosity) and the likelihood of rapid crystallization. It is also a quantitative description of the high molecular weight fraction, compared to the complex melt shear viscosity η measured at a frequency of 0.02 rad / s as described above. 0.02 And the amount of comonomer incorporated during delayed crystallization (e.g., from the maximum heat flow time t during static crystallization). maxDSC (Quantitative) correlation.

[0127] The t was determined using a TA instrument Q2000 differential scanning calorimeter under isothermal conditions at a constant temperature of 124℃. maxDSC Weigh 5 to 6 mg of sample and place it in an aluminum DSC pan. Heat the sample to 200 °C at 20 K / min and cool it to the test temperature at 20 K / min to eliminate thermal history. Immediately begin the isothermal test and record the time until crystallization occurs. Use the supplier's software (TA Instruments) to determine the time interval t until the maximum heat flux (peak) of crystallization. maxDSC Repeat the measurement 3x times and then calculate the average (in minutes). If no crystallization is observed within 120 minutes under these conditions, then t maxDSC =The value for 120 minutes is used for further calculation of the HMWcopo index.

[0128] melt viscosity η 0.02 Value multiplied by t maxDSC The value is calculated, and the product is normalized using a factor of 100000 (10^5).

[0129] Molecular weight distribution determination

[0130] The molar mass distribution and the derived average values ​​Mn, Mw, Mz, and Mw / Mn were determined by high-temperature gel permeation chromatography using the methods described in ISO 16014-1, -2, -4, issued in 2003. Details according to the ISO standard are as follows: solvent 1,2,4-trichlorobenzene (TCB); equipment and solution temperature 135°C; and a PolymerChar (Paterna 46980, Valencia, Spain) IR-4 infrared detector compatible with TCB as the concentration detector. A WATERSAlliance 2000 system was used, equipped with a SHODEX UT-G pre-column and SHODEX UT 806M (3x) and SHODEX UT 807 (Showa Denko Europe GmbH, Konrad-Zuse-Platz 4, 81829 Munich, Germany) connected in series.

[0131] The solvent was vacuum distilled under nitrogen and stabilized with 0.025 wt% 2,6-di-tert-butyl-4-methylphenol. The flow rate used was 1 ml / min, the injection volume was 500 μl, and the polymer concentration was in the range of 0.01% < concentration < 0.05% w / w. Molecular weight calibration was established using monodisperse polystyrene (PS) standards from a polymer laboratory (now Agilent Technologies, Herrenberger Str. 130, 71034 Boeblingen, Germany) ranging from 580 g / mol to 11,600,000 g / mol, with the addition of hexadecane.

[0132] The calibration curve was then adapted to polyethylene (PE) using a universal calibration method (Benoit H., Rempp P. and Grubisic Z., *Journal of Polymer Science*, Phys., 5, 753 (1967)). The Mark-Houwing parameter used here for PS is: k PS = 0.000121 dl / g, α PS =0.706, and used for PE, k PE = 0.000406 dl / g, α PE =0.725, effective in a TCB at 135℃. NTGPC_Control_V6.02.03 and NTGPC_V6.4.24 (HS Corporation) were used respectively. 36, D-55437 Ober-Hilbersheim, Germany) for data recording, calibration and calculation.

[0133] Melt Flow Index

[0134] Determined at 190°C and specified load according to ISO 1133-12012-03.

[0135] Long Chain Branching Index (LCBI)

[0136] The LCB index corresponds to 10 6 The branching factor g' was measured at a molecular weight of g / mol. The branching factor g' was measured by gel permeation chromatography (GPC) combined with multi-angle laser scattering (MALLS), which allows for the determination of long-chain branches at high Mw. The radius of gyration of each fraction eluted from GPC (as described above, but with a flow rate of 0.6 ml / min and a column packed with 30 μm particles) was measured by analyzing light scattering at different angles using MALLS (detector: Wyatt Dawn EOS, Wyatt Technology, Santa Barbara, California). A 120 mW laser source at a wavelength of 658 nm was used. The specific refractive index was taken as 0.104 ml / g. Data were evaluated using Wyatt ASTRA 4.7.3 and CORONA 1.4 software. The LCB index was determined as described below.

[0137] The parameter g' is the ratio of the measured radius of gyration to the radius of gyration of a linear polymer with the same molecular weight. A linear molecule shows g' as 1, while values ​​less than 1 indicate the presence of LCB. The value of g' as a function of molecular weight M is calculated by the following equation:

[0138] g'(M)= <Rg 2 > 样品,M / <Rg 2 > 线性参考,M

[0139] in <Rg 2 >, M is the root mean square radius of gyration of the fraction of molecular weight M.

[0140] The radii of rotation of each fraction eluted from a GPC (as described above, but with a flow rate of 0.6 ml / min and a column packed with 30 μm particles) were measured by analyzing light scattering at different angles. Therefore, the molecular weight M and radii of rotation can be determined from this MALLS setup. <Rg 2 > 样品,M And defined in the measurement M=10 6 g' at g / mol. <Rg 2 >线性参考,M The relationship was calculated from the established relationship between the radius of gyration and molecular weight of linear polymers in solution (Zimm and Stockmayer WH 1949) and confirmed by measuring linear PE references using the same equipment and methods described.

[0141] The same scheme is described in the following document.

[0142] Zimm BH, Stockmayer WH (1949), "The dimensions of chain molecules containing branches and rings." *Journal of Chemical Physics*, 17.

[0143] Rubinstein M., Colby RH. (2003), *Polymer Physics*, Oxford University Press.

[0144] Comonomer content

[0145] According to ASTM D 624898, the comonomer content was determined by IR spectroscopy using a Tensor27 FT-IR spectrometer from Bruker. This Tensor27 FT-IR spectrometer was calibrated with a stoichiometric model used to determine the ethyl or butyl side chains of butene or hexene as comonomers in PE. The results were compared with estimates of comonomer content derived from the mass balance of the polymerization process, and the results were found to be consistent.

[0146] swelling ratio

[0147] Using a capillary rheometer The Rheotester 2000 and Rheograph 25 were used to measure the swelling ratio of the studied polymers at T = 190 °C. The capillary rheometer was equipped with a commercial 30 / 2 / 2 / 20 die (total length 30 mm, effective length = 2 mm, diameter = 2 mm, L / D = 2 / 2 and 20° incident angle) and an optical device for measuring the thickness of the extruded wire (from...). (laser diode). The sample was melted in a capillary tube at 190°C for 6 minutes and at a time corresponding to 1440 s. -1 The piston speed at which the shear rate is obtained at the die is extruded.

[0148] When the piston reaches a position 96 mm from the die inlet, the extrudate is cut at a distance of 150 mm from the die outlet (via the material from...). (Automatic cutting device). The extrusion diameter is measured using a laser diode at a distance of 78 mm from the die exit, as a function of time. The maximum value corresponds to D. 挤出物 The swelling ratio is determined by the following calculations:

[0149] SR=(D 挤出物 -D 压模 100% / D 压模

[0150] Where D 压模 It is the corresponding diameter at the mold exit measured using a laser diode.

[0151] AZK Notch Tensile Impact Test

[0152] Tensile-impact strength was determined using a Type 1 double-notched specimen according to Method A, ISO 8256:2004. The test specimen (4 × 10 × 80 mm) was cut from a compression-molded sheet prepared according to ISO 1872-2 requirements (average cooling rate of 15 K / min and high pressure during the cooling phase). The specimen had 45° V-shaped notches on both sides. The depth was 2 ± 0.1 mm, and the radius of curvature of the notch angle was 1.0 ± 0.05 mm.

[0153] The free length between the clamps is 30 ± 2 mm. Before measurement, all test specimens are conditioned at a constant temperature of -30°C for 2 to 3 hours. The procedure for measuring tensile impact strength is described in ISO 8256, including energy correction following Method A.

[0154] ESCRBelltest

[0155] Environmental stress cracking resistance (ESCR Bell telephone test) was measured according to ASTM D1693:2013 (Method B) and DIN EN ISO 22088-3:2006. Ten rectangular test specimens (38 × 13 × 2 mm) were cut from a compression-molded sheet prepared according to ISO 1872-2 requirements (average cooling rate of 15 K / min and high pressure during the cooling phase). A 0.4 mm deep slit was cut parallel to the longitudinal axis in the center of one of the wide faces using a razor. They were then bent into a U-shape using a special bending device, with the slit facing upwards. Within 10 minutes of bending, the U-shaped specimens were placed in a glass tube and filled with a 10 vol% aqueous solution of 4-nonylphenyl-polyethylene glycol (Arkopal N100) at 50°C, and sealed with a rubber stopper. Cracks were visually inspected hourly on the first day, then daily, and then weekly (every 168 hours) after 7 days. The final value obtained is the 50% breakage point (F) of the 10 test specimens in the glass tube. 50 ).

[0156] Environmental stress cracking resistance based on full-cut creep test (FNCT)

[0157] The environmental stress cracking resistance of the polymer samples was determined in an aqueous surfactant solution according to the international standard ISO 16770:2004 (FNCT). A 10 mm thick sheet was prepared from the polymer sample using compression molding. A rod with a square cross-section (10 × 10 × 100 mm) was slit on four sides perpendicular to the stress direction using a razor blade. The slitting device described by M. Fleissner in Kunststoffe 77 (1987), page 45, was used for sharp slits with a depth of 1.6 mm.

[0158] The applied load is calculated by dividing the tensile force by the initial ligament area. The ligament area is the remaining area = total cross-sectional area of ​​the specimen minus the notch area. For FNCT specimens: 10 × 10 mm 2 -4 times the area of ​​the trapezoidal cut = 46.24 mm 2 (Remaining cross-section of the failure process / crack propagation). Test specimens were loaded with a 2% (by weight) aqueous solution of the nonionic surfactant ARKOPALN100 under the standard conditions recommended by ISO 16770, wherein a constant load of 4 MPa was applied at 80°C or a constant load of 6 MPa was applied at 50°C. The time to fracture of the test specimen was detected.

[0159] Shabi aCN

[0160] Fracture toughness was determined by an internal method on 10×10×80 mm test bars cut from 10 mm thick compression-molded sheets. Six of these test bars were centrally incised using a razor blade from the aforementioned incision apparatus for FNCT. The incision depth was 1.6 mm. The measurement was performed essentially according to the Charpy method of ISO 179-1, with a modified test specimen and a modified impact geometry (distance between the carriers).

[0161] All test specimens were conditioned to a measurement temperature of -30°C over a period of 2 to 3 hours. Then, according to ISO 179-1, the test specimens were placed without delay on the supports of the pendulum impact tester. The distance between the supports was 60 mm. A 2J hammer was triggered with a drop angle of 160°, a pendulum length of 225 mm, and an impact velocity of 2.93 m / s. The fracture toughness value was expressed in kJ / m³. 2 It is expressed as the quotient of the impact energy consumed and the initial cross-sectional area aCN at the notch. The values ​​for complete fracture and hinge fracture can be used here as the basis for general meaning (see Recommendation 179-1).

[0162] Cast film measurement

[0163] Membrane measurements of the gel were performed on an OCS extruder ME 202008-V3, which has a screw diameter of 20 mm, a screw length of 25 D, and a slot die width of 150 mm. The casting line was equipped with cooling rollers and a winding machine (model OCS CR-9). Optical equipment consisted of an OSC membrane surface analyzer camera, model FTA-100 (flash camera system), with a resolution of 26 μm × 26 μm. After purging the resin for 1 hour to stabilize extrusion conditions, checks and values ​​were recorded after 30 minutes. The resin was extruded at 220°C at a feed rate of ca. 2.7 m / min to produce a 50 μm thick film. The cooling roller temperature was 70°C.

[0164] The examination using a surface analyzer camera provided the total gel content and the content of gel with a diameter greater than 700 μm, as reported in Table 1.

[0165] E-modulus

[0166] Tensile testing was conducted according to ISO 527-1:2019 / -2:2012, Method B, under standard climatic conditions (50% relative humidity and 23°C). ISO 20753:2018 Type A2 (= ISO 527-21 Type B) test specimens (h = 4 mm, b1 = 10 mm, b2 = 20 mm, l3 ≥ 150 mm, L0 = 50 mm) were cut from compression-molded sheets prepared according to ISO 2818:2018, as per the requirements of ISO 293:2004 and ISO 17855-2:2016 (average cooling rate of 15 K / min and 10 MPa during the pressure and cooling phases). According to ISO 291:2008, the cut Type B test specimens were conditioned under standard climatic conditions for >16 hours and then measured on a Zwick Allround Z010 Liner as described in ISO 527-2. E-modulus was determined using a measurement speed of 1 mm / min.

[0167] - Process settings

[0168] The polymerization process is carried out under continuous conditions in a facility comprising two gas-phase reactors connected in series, such as... Figure 1 As shown.

[0169] The polymerization catalyst is prepared as follows.

[0170] Preparation procedure of catalyst components

[0171] Magnesium chloride and alcohol adduct containing about 3 moles of alcohol were prepared according to the method described in Example 2 of USP 4,399,054, but at 2000 RPM instead of 10000 RPM. The adduct was heat-treated under a nitrogen flow at a temperature range of 50 to 150 °C until an alcohol content of 25% by weight was achieved.

[0172] At 0°C, 1 L of TiCl4 was introduced into a 2 L four-necked round-bottom flask purged with nitrogen. Then, at the same temperature, 70 g of the spherical MgCl2 / EtOH adduct prepared as described above, containing 25 wt% ethanol, was added with stirring. The temperature was raised to 140°C and maintained for 120 minutes over 2 hours. Then, stirring was stopped, the solid product was allowed to settle, and the supernatant was siphoned off. The solid residue was then washed once with heptane at 80°C and five times with hexane at 25°C, and dried under vacuum at 30°C.

[0173] At 20°C, a 260cm container equipped with a stirrer was prepared. 3 351.5 cm³ was introduced into the glass reactor. 3 Hexane was added, and 7g of the catalyst component prepared as described above was introduced at 20°C while stirring. The internal temperature was kept constant, and a 5.6cm...3 A hexane solution of tri-n-octyl aluminum (TNOA) (approximately 370 g / L) and a certain amount of cyclohexylmethyl-dimethoxysilane (CMMS) (e.g., a TNOA / CMMS molar ratio of 50) were slowly introduced into the reactor, and the temperature was raised to 10°C. After stirring for 10 minutes, 10 g of propylene was carefully introduced into the reactor over a period of 4 hours at the same temperature. The consumption of propylene in the reactor was monitored, and polymerization was stopped when the theoretical conversion of 1 g of polymer per g of catalyst was considered to have been reached. The entire contents were then filtered and washed three times with hexane (50 g / L) at 30°C. After drying, the resulting prepolymerized catalyst (A) was analyzed, and it was found that each gram of initial catalyst contained 1.05 g of polypropylene, 2.7% Ti, 8.94% Mg, and 0.1% Al.

[0174] Internal electron donor support on prepolymerized catalyst

[0175] Approximately 42 g of the solid prepolymer catalyst prepared as described above was loaded into a glass reactor purged with nitrogen and slurried with 0.8 L of hexane at 50 °C.

[0176] Then, ethyl acetate was carefully added dropwise (over 10 minutes) in an amount such that the molar ratio between Mg in the prepolymer catalyst and the organic Lewis base was 1.7.

[0177] The slurry was kept at an internal temperature of 50°C for 2 hours while being stirred.

[0178] Then stop stirring and allow the solids to settle. Perform a single hexane wash at room temperature before recovering and drying the final catalyst.

[0179] Example 1

[0180] polymerization

[0181] Using 1 kg / h of liquid propane, a solid catalyst with a molar feed ratio of 11 g / h of electron donor / Ti prepared as described above, at a ratio of 8, was fed into a first stirred pre-contact vessel, wherein triisobutylaluminum (TIBA) and diethylaluminum chloride (DEAC) were also metered in. The weight ratio of triisobutylaluminum to diethylaluminum chloride was 7:1. The ratio of alkylaluminum (TIBA+DEAC) to solid catalyst was 5:1. The first pre-contact vessel was maintained at 50°C for an average residence time of 30 minutes. The catalyst suspension in the first pre-contact vessel was continuously transferred to a second stirred pre-contact vessel, which was operated with an average residence time of 30 minutes and also maintained at 50°C. The catalyst suspension was then continuously transferred to a fluidized bed reactor (FBR) (1) via line (10).

[0182] In the first reactor, ethylene is polymerized using H2 as a molecular weight regulator and in the presence of propane as an inert diluent. 49 kg / h of ethylene and 210 g / h of hydrogen are fed into the first reactor via pipeline 9. No comonomer is fed into the first reactor.

[0183] Polymerization is carried out at a temperature of 80°C and a pressure of 2.9 MPa. The polymer obtained in the first reactor is discharged discontinuously via line 11, separated from the gas and fed into a gas / solid separator 12, and then reintroduced into the second gas phase reactor via line 14.

[0184] The polymer produced in the first reactor has a melt index (MIE) of approximately 87 g / 10 min and a melt flow rate of 0.969 kg / dm³. 3 The density.

[0185] The second reactor operates at polymerization conditions of approximately 89°C and a pressure of 2.5 MPa. The riser has an inner diameter of 200 mm and a length of 19 m. The downcomer has a total length of 18 m, with the upper section being 5 m long and having an inner diameter of 300 mm, and the lower section being 13 m long and having an inner diameter of 150 mm. To broaden the molecular weight distribution of the final ethylene polymer, the second reactor is operated under different conditions of monomer and hydrogen concentrations within riser 32 and downcomer 33. This is achieved by feeding a liquid stream (liquid separator) of 330 kg / h into the upper part of downcomer 33 via line 52. The liquid stream has a different composition than the gas mixture present in the riser. The different concentrations of monomer and hydrogen and the composition of the liquid separator in the riser and downcomer of the second reactor are shown in Table 1. The liquid stream from line 52 operates at 52°C and 2.5 MPa from a condensation step in condenser 49, where a portion of the recirculated stream is cooled and partially condensed. As shown in the figure, the separation container and pump are placed sequentially downstream of condenser 49. The monomer enters the downcomer at three feed points (line 46). At feed point 1, just below the separator, 12 kg / h of ethylene and 0.10 kg / h of 1-hexene are introduced. At feed point 2, 2 kg / h of ethylene is introduced 2.3 meters below the feed point. At feed point 3, 2 kg / h of ethylene is introduced 4 meters below the feed point. At each of the three feed points, liquid drawn from feed stream 52 is additionally fed at a 1:1 ratio with ethylene. 5 kg / h of propane, 30 kg / h of ethylene, and 35 g / h of hydrogen are fed into the circulation system through line 45.

[0186] The final polymer is discharged discontinuously via pipeline 54.

[0187] Further details regarding the aggregation conditions are reported in Table 1.

[0188] The polymerization process in the second reactor produces relatively high molecular weight polyethylene fractions.

[0189] Table 2 specifies the characteristics of the final product. It can be seen that the melt index of the final product is lower than that of the ethylene resin produced in the first reactor, indicating the formation of a high molecular weight fraction in the second reactor.

[0190] The first reactor produces approximately 52% by weight (split weight%) of the total final polyethylene resin produced by the first and second reactors.

[0191] The amount of comonomer (hexene-1) is approximately 0.1% by weight.

[0192] Comparison Example 1

[0193] polymerization

[0194] Using 1 kg / h of liquid propane, a solid catalyst with a molar feed ratio of 10 g / h of electron donor / Ti prepared as described above, at a ratio of 8, was fed into a first stirred pre-contact vessel, wherein triisobutylaluminum (TIBA) and diethylaluminum chloride (DEAC) were also metered in. The weight ratio of triisobutylaluminum to diethylaluminum chloride was 7:1. The ratio of alkylaluminum (TIBA+DEAC) to solid catalyst was 5:1. The first pre-contact vessel was maintained at 50°C for an average residence time of 30 minutes. The catalyst suspension in the first pre-contact vessel was continuously transferred to a second stirred pre-contact vessel, which was operated with an average residence time of 30 minutes and also maintained at 50°C. The catalyst suspension was then continuously transferred to a fluidized bed reactor (FBR) (1) via line (10).

[0195] In the first reactor, ethylene is polymerized using H2 as a molecular weight regulator and in the presence of propane as an inert diluent. 50 kg / h of ethylene and 215 g / h of hydrogen are fed into the first reactor via pipeline 9. No comonomer is fed into the first reactor.

[0196] Polymerization is carried out at a temperature of 80°C and a pressure of 2.9 MPa. The polymer obtained in the first reactor is discharged discontinuously via line 11, separated from the gas and fed into a gas / solid separator 12, and then reintroduced into the second gas phase reactor via line 14.

[0197] The polymer produced in the first reactor has a melt index (MIE) of approximately 71 g / 10 min and a melt flow rate of 0.967 kg / dm³. 3 The density.

[0198] The second reactor operates at polymerization conditions of approximately 85°C and a pressure of 2.5 MPa. The riser has an inner diameter of 200 mm and a length of 19 m. The downcomer has a total length of 18 m, with the upper section being 5 m long and having an inner diameter of 300 mm, and the lower section being 13 m long and having an inner diameter of 150 mm. To broaden the molecular weight distribution of the final ethylene polymer, the second reactor is operated by establishing different monomer and hydrogen concentrations within the riser 32 and downcomer 33. This is achieved by feeding a liquid stream (liquid separator) of 330 kg / h into the upper part of the downcomer 33 via line 52. The liquid stream has a different composition than the gas mixture present in the riser. The different concentrations of monomer and hydrogen and the composition of the liquid separator in the riser and downcomer of the second reactor are shown in Table 1. The liquid stream from line 52 operates at 51°C and 2.5 MPa from a condensation step in condenser 49, where a portion of the recirculated stream is cooled and partially condensed. As shown in the figure, the separation container and pump are placed sequentially downstream of condenser 49. The monomer enters the downcomer at three feed points (line 46). At feed point 1, just below the separator, 10 kg / h of ethylene and 0.45 kg / h of 1-hexene are introduced. At feed point 2, 4 kg / h of ethylene is introduced 2.3 meters below the feed point. At feed point 3, 4 kg / h of ethylene is introduced 4 meters below the feed point. At each of the three feed points, liquid drawn from feed stream 52 is additionally fed at a 1:1 ratio with ethylene. 5 kg / h of propane, 32 kg / h of ethylene, and 35 g / h of hydrogen are fed into the circulation system through line 45.

[0199] The final polymer is discharged discontinuously via pipeline 54.

[0200] Further details regarding the aggregation conditions are reported in Table 1.

[0201] The polymerization process in the second reactor produces relatively high molecular weight polyethylene fractions.

[0202] Table 2 specifies the characteristics of the final product. It can be seen that the melt index of the final product is lower than that of the ethylene resin produced in the first reactor, indicating the formation of a high molecular weight fraction in the second reactor.

[0203] The first reactor produces approximately 49% by weight (split weight%) of the total final polyethylene resin produced by the first and second reactors.

[0204] The amount of comonomer (hexene-1) is approximately 0.4% by weight.

[0205] Comparison Example 2

[0206] The polymer in this comparative example is a polyethylene composition produced by a slurry process in the presence of a Ziegler catalyst using butene-1 as a comonomer, sold by Dow under trademark 35060E XG21081404.

[0207] Table 1

[0208] Operating conditions for the first reactor <![CDATA[H2 / C2H4 molar ratio]]> 2.8 2.6 <![CDATA[C2H4%]]> 10.7 10.3 <![CDATA[The density of (A) (g / cm 3 )]]> 0.969 0.967 A) MIE [2.16kg] (g / 10 minutes) 87 71 Splitting (wt%) 52 49 Operating conditions for the second reactor <![CDATA[H2 / C2H4 molar ratio riser]]> 0.5 0.35 <![CDATA[C2H4% riser]]> 10 12 <![CDATA[C6H 12 %lift pipe]]> 0.06 0.17 <![CDATA[H2 / C2H4 molar ratio decreasing tube]]> 0.07 0.10 <![CDATA[C2H4% downcomer]]> 6 5 <![CDATA[C6H 12 % downcomer 0.05 0.4 <![CDATA[H2 / C2H4 molar ratio isolator]]> 0.082 0.056 <![CDATA[C2H4% Isolator]]> 6.1 7.0 <![CDATA[C6H 12 % isolation material]]> 0.12 0.31

[0209] Table 2

[0210] Final polymer properties MIP[5kg](g / 10min) 2.4 1.39 1.3 MIF [21.6kg] (g / 10 minutes) 49.9 28 27.3 MIF / MIP 20.7 20.1 21.5 MIE [2.16kg] 0.53 0.33 - <![CDATA[Density (g / cm 3 )]]> 0.9606 0.959 0.958 Swelling ratio (%) 193 167 166 Mw(g / mol) 252240 265973 194155 Mz(g / mol) 1751190 1525400 1462533 Mw / Mn 33.9 31.0 29.53 LCBI 0.56 0.63 0.7 Comonomer content IR (wt%) <![CDATA[0.1(C6H 12 )]]> <![CDATA[0.4(C6H 12 )]]> <![CDATA[0.8(C4H8)]]> <![CDATA[η 0.02 ]]> 31481 36504 44846 <![CDATA[(η 0.02 / 1000) / LCBI]]> 56.2 57.6 64 <![CDATA[AZK-30℃(kJ / m 2 )]]> 83.4 85.3 56.2 <![CDATA[Charpy aCN, T = -30 °C (kJ / m 2 )]]> 4.8 6.5 4.1 Belltest at 50°C 84 226 - FNCT*4MPa / 80℃ (hours) 1.2 2 3.1 FNCT*6MPa / 50℃ (hours) 7.7 12.6 - E-Modulus (ISO527-2 / 1B / 50) (MPa) 1520 1440 - <![CDATA[Total number of gels / m 2 > 450 μm]]> 1.7 3.0 - <![CDATA[Total number of gels / m 2 >700μm]]> 0.0 0.0 - <![CDATA[Total number of gels / m 2 Total]]> 443 264 - HMWCOPO Index 0.3 0.58 - ET 10.1 5.8 - ER 3.1 2.7 -

[0211] Note: C2H4 = ethylene; C6H 12 = Hexene; C4H8 = Butene; *2% aqueous solution of Arkopal N100

Claims

1. A polyethylene composition having the following characteristics: 1) from 0.957 to 0.968 g / cm 3 Density, determined according to ISO 1183-1 :2012 at 23 °C; 2) MIF / MIP ratios from 12 to 30, where MIF is the melt flow index at 190°C and 21.60 kg load, and MIP is the melt flow index at 190°C and 5 kg load, both determined according to ISO 1133-1 2012-03. 3) MIF from 45 to 55 g / 10 minutes; 4) A long-chain branching index (LCBI) equal to or greater than 0.45, where the LCBI is the measured mean square radius of gyration R measured by GPC-MALLS. g The ratio of the radius of gyration of linear PE with the same molecular weight; 5) In η 0.02 Divide by 1000 and LCBI, from 45 to 75 (η) 0.02 / 1000) / LCBI ratio; 6) Mz / Mw equal to or greater than 6.5; and 7) 2 to 8 g / 10 minutes of MIP, The polyethylene composition comprises: A) 30 to 70% by weight of ethylene homopolymer or copolymer, said ethylene homopolymer or copolymer having a concentration equal to or greater than 0.960 g / cm³. 3 Density and MIE of 65 g / 10 minutes or higher; B) 30 to 70% by weight of an ethylene copolymer having a lower MIE value than that of A), wherein the MIE is the melt flow index at 190°C and a load of 2.16 kg as determined according to ISO 1133-1 2012-03.

2. The polyethylene composition according to claim 1, wherein the density is 0.958 to 0.968 g / cm³.

3. The polyethylene composition according to claim 1, wherein the density is from 0.959 to 0.965 g / cm³.

4. The polyethylene composition according to claim 1, wherein the MIF / MIP ratio is 15 to 25.

5. The polyethylene composition according to claim 1, wherein the MIF / MIP ratio is 15 to 23.

6. The polyethylene composition according to claim 1, wherein the LCBI is greater than or equal to 0.

50.

7. The polyethylene composition according to claim 1, wherein the (η0.02 / 1000) / LCBI ratio is 50 to 70.

8. The polyethylene composition according to claim 1, wherein the polyethylene composition comprises one or more ethylene copolymers.

9. The polyethylene composition according to any one of claims 1 to 8, wherein the polyethylene composition can be obtained by using a Ziegler-Natta polymerization catalyst.

10. The polyethylene composition of claim 9, wherein the Ziegler-Natta polymerization catalyst comprises the following reaction product: a) A solid catalyst component comprising a Ti compound supported on MgCl2, said component being obtained by contacting the titanium compound with the MgCl2 or a precursor Mg compound, optionally in the presence of an inert medium, thereby obtaining intermediate a'), and then subjecting a') to prepolymerization and contact with an electron donor compound; b) Organic-Al compounds; and optionally c) External electron donor compounds.

11. The polyethylene composition according to claim 1, wherein the polyethylene composition has at least one of the following additional features: -η from 25,000 to 38,000 Pa.s 0.02 , where η 0.02 It is the complex shear viscosity at an angular frequency of 0.02 rad / s, measured using dynamic oscillatory shear in a plate-to-plate rotational rheometer at a temperature of 190°C. - The content of comonomers is equal to or less than 0.3% by weight relative to the total weight of the composition; - Mw equal to or greater than 230,000 g / mol, where Mw is the weight-average molecular weight as measured by GPC; - Mz equal to or greater than 1,000,000 g / mol, where Mz is the z-average molecular weight as measured by GPC; - Mz / Mw from 6.5 to 9; - MIE equal to or less than 0.8 g / 10 min, where MIE is the melt flow index at 190 °C and 2.16 kg load as determined according to ISO 1133-1 2012-03; - An ER equal to or greater than 1, wherein the ER is calculated according to the following formula: ER = (1.781 × 10 -3 )×G', where G''=5,000dyn / cm 2 Under the value of , where G' is the energy storage modulus and G'' is the loss modulus; - ET equal to or less than 25, wherein ET is calculated according to the following formula: ET = C2 / G, where tan δ = C3, and: G = [(G')] 2 + (G'') 2 ] 1 / 2 ; tan δ = G'' / G'; C2 = 10 6 dyn / cm 2 And C3 = 1.5, where G' is the energy storage modulus and G'' is the loss modulus; - HMWcopo index from 0.1 to 3; The HMWcopo index is determined according to the following formula: HMWcopo = (η 0.02 x t maxDSC ) / (10^5) The tmaxDSC mentioned therein is the time in minutes required to reach the maximum heat flux in mW at a temperature of 124°C, measured in a differential scanning calorimeter DSC in isothermal mode under static conditions.

12. The polyethylene composition according to claim 11, wherein η0.02 is from 25,000 to 34,000 Pa·s.

13. The polyethylene composition according to claim 11, wherein the comonomer content is 0.05 to 0.3 by weight.

14. The polyethylene composition according to claim 11, wherein Mw is 230,000 to 400,000 g / mol.

15. The polyethylene composition according to claim 11, wherein Mz is from 1,000,000 to 2,500,000 g / mol.

16. The polyethylene composition of claim 11, wherein the MIE is 0.8 to 0.1 g / 10 min.

17. The polyethylene composition of claim 11, wherein ER is greater than or equal to 1.

5.

18. The polyethylene composition according to claim 11, wherein ER is 1 to 8.

19. The polyethylene composition according to claim 11, wherein ER is 1.5 to 8.

20. The polyethylene composition according to claim 11, wherein ET is 3 to 25.

21. The polyethylene composition according to claim 11, wherein ET is 7 to 25.

22. The polyethylene composition according to claim 11, wherein the HMWcopo index is 0.1 to 2.

23. The polyethylene composition according to claim 1, wherein the polyethylene composition comprises one or more ethylene copolymers.

24. The polyethylene composition of claim 1, wherein the polyethylene composition comprises 40 to 60% by weight of ethylene homopolymer or copolymer as component A.

25. The polyethylene composition according to claim 1, wherein component A) is an ethylene homopolymer.

26. The polyethylene composition according to claim 1, wherein the MIE of component A) is 75 g / 10 min or higher.

27. The polyethylene composition according to claim 1, wherein the MIE of component A) is 65 to 100 g / 10 min.

28. The polyethylene composition according to claim 1, wherein the MIE of component A) is 75 to 100 g / 10 min.

29. The polyethylene composition of claim 1, wherein the polyethylene composition comprises 40 to 60% by weight of an ethylene copolymer as component B.

30. The polyethylene composition according to claim 1, wherein the MIE of component B) is less than 0.5 g / 10 min.

31. The polyethylene composition according to claim 1, wherein the difference between the density value of component A) and the density value of the composition is equal to or less than 15 kg / m³. 3 .

32. The polyethylene composition of claim 31, wherein the difference is 15 to 5 kg / m³. 3 .

33. Articles of manufacture comprising the polyethylene composition according to claim 1.

34. The manufactured article according to claim 33, wherein the manufactured article is in the form of a blow-molded article.

35. The manufactured article according to claim 34, wherein the capacity is 200 to 5000 cm³. 3 Blow-molded containers.

36. The manufactured article according to claim 34, wherein it is a blow-molded dairy and beverage bottle.

37. A process for preparing the polyethylene composition according to claim 1, wherein all polymerization steps are carried out in the presence of a Ziegler-Natta polymerization catalyst supported on MgCl2.

38. The process of claim 37, wherein the process comprises the following steps in any mutually sequential order: a) In a gas-phase reactor, ethylene is optionally polymerized with one or more comonomers in the presence of hydrogen; b) In another gas-phase reactor, in the presence of hydrogen in an amount less than that in step a), copolymerize ethylene with one or more comonomers; In at least one of the gas-phase reactors, the grown polymer particles flow upward through a first polymerization zone under rapid fluidization or conveying conditions, leave the first polymerization zone and enter a second polymerization zone, and then flow downward through the second polymerization zone under gravity, leave the second polymerization zone and be reintroduced into the first polymerization zone, thereby establishing a polymer cycle between the two polymerization zones.

Images