Polymerization process, HDPE polyethylene composition, and rotationally molded product

Abstract

A solution-phase polymerization process using a metallocene catalyst in the first reactor and a Ziegler-Natta catalyst in the second reactor yielded 0.942 g / cm³. 3 A high-density polyethylene composition is obtained having a density and a melt index I2 exceeding 5.0 g / 10 min. When prepared into plaque, the high-density polyethylene resin has an environmental stress crack resistance (ESCR) exceeding 1000 hours (determined by ASTM D1693 in 100% IGEPAL CO-630 under condition B) and an IZOD impact strength of 10 feed-pounds / inch or more. The polyethylene composition containing the first and second ethylene copolymers is relatively easy to process and can be used in the manufacture of molded articles.

Description

[Technical Field]

[0001] This disclosure relates to a solution-phase polymerization process and the high-density polyethylene composition obtained, wherein the high-density polyethylene composition flows well and has a density of 0.942 g / cm³. 3 It possesses densities within the above range, exhibits good environmental stress crack resistance (ESCR performance), and high IZOD impact strength. The resulting high-density polyethylene composition has attractive properties for use in the formation of rotationally molded articles. [Background technology]

[0002] When developing thermoplastic resins suitable for use in the preparation of molded parts such as rotationally molded parts, key considerations include the time required for molding the part (e.g., the flow rate of molten resin in the mold, the rate of resin sintering and cooling, etc.), impact resistance, and resistance to environmental stress over time (e.g., environmental stress crack resistance).

[0003] While several polyethylene resins suitable for use in molded parts have been developed (e.g., U.S. Patent Applications Publications 2016 / 0229964, 2017 / 0267822, and U.S. Patents 9,181,422, 9,540,505, 9,695,309, 10,519,304, 10,329,412, 10,053,564, 9,758,653, 9,637,628, 9,475,927, 9,221,966, 9,074,082, 8,962,755, and 8,022,143), there is still a need for novel polyethylene resins that simultaneously exhibit high fluidity, good rigidity and toughness, and environmental resistance. [Overview of the project]

[0004] We have developed a polyethylene composition with good flow properties, relatively high density and rigidity, and good environmental stress crack resistance and impact properties. This polyethylene composition may be useful in the manufacture of molded products, such as rotationally molded articles.

[0005] One embodiment of the present disclosure is a polyethylene composition, (i) a density of 0.880 to 0.930 g / cm 3 , a molecular weight distribution M w / M n of 1.7 to 2.7, and a weight average molecular weight M w of 75,000 to 250,000 g / mol, and 10 to 60 weight percent of a first ethylene copolymer, (ii) a density of 0.945 to 0.965 g / cm 3 , a molecular weight distribution M w / M n of 2.1 to 3.5, and a weight average molecular weight M w of 15,000 to 75,000 g / mol, and 90 to 40 weight percent of a second ethylene copolymer and comprising, wherein the ratio SCB1 / SCB2 of the number of short chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.0, the polyethylene composition has a density of 0.942 g / cm 3 or more, a melt index I2 exceeding 5.0 g / 10 min, a melt flow ratio I 21 / I2 of 50 or less, and a long chain branching coefficient LCBF of 0.0010 or more, and is a polyethylene composition.

[0006] In one embodiment of the present disclosure, the polyethylene composition has an LCBF of 0.0010 to 0.0090.

[0007] In one embodiment of the present disclosure, the polyethylene composition has an LCBF of 0.0010 or more and less than 0.0060.

[0008] In one embodiment of the present disclosure, the polyethylene composition or a plaque made therefrom has an environmental stress crack resistance ESCR (determined by ASTM D1693 under condition B in 100% IGEPAL® CO-630) exceeding 500 hours.

[0009] In one embodiment of the present disclosure, a polyethylene composition or a plaque made therefrom has an environmental stress crack resistance (ESCR) of more than 1000 hours (determined by ASTM D1693 in 100% IGEPAL CO-630 under condition B).

[0010] In one embodiment of the present disclosure, a polyethylene composition or a plaque made therefrom has an environmental stress crack resistance (ESCR) of more than 500 hours (determined by ASTM D1693 in 10% IGEPAL CO-630 under condition B).

[0011] In one embodiment of the present disclosure, a polyethylene composition or a plaque made therefrom has an environmental stress crack resistance (ESCR) of more than 1000 hours (determined by ASTM D1693 in 10% IGEPAL CO-630 under condition B).

[0012] In one embodiment of the present disclosure, a polyethylene composition or a plaque made therefrom has an Izod impact value greater than 9.0 ft-pounds / inch.

[0013] In one embodiment of the present disclosure, a polyethylene composition or a plaque made therefrom has an Izod impact value of at least 10.0 ft-pounds / inch.

[0014] In one embodiment of the present disclosure, the polyethylene composition has an elastic ratio G' / G'' of less than 0.17 at 0.5 rad / s.

[0015] In one embodiment of this disclosure, the polyethylene composition has a flexural cleavage modulus of 900 MPa or more at 1%.

[0016] In one embodiment of the present disclosure, the polyethylene composition contains an additive package comprising a hindered monophosphite, a diphosphite, a hindered amine light stabilizer, and at least one additional additive selected from the group consisting of hindered phenol and hydroxylamine.

[0017] One embodiment of the present disclosure is a solution-phase polymerization process for producing a polyethylene composition, The solution-phase polymerization process is A step of polymerizing ethylene and alpha-olefin using a metallocene catalyst in a first reactor, The process involves polymerizing ethylene and alpha-olefin using a Ziegler-Natta catalyst in a second reactor. Includes, The first reactor and the second reactor are configured in series with each other. Polyethylene composition, (i) 0.880~0.930 g / cm³ 3 Density, molecular weight distribution M (1.7-2.7) w / M n , and weight-average molecular weight M of 75,000 to 250,000 g / mol w A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945~0.965 g / cm³ 3 Density, molecular weight distribution M 2.0~3.5 w / M n , and weight-average molecular weight M of 15,000 to 75,000 g / mol w Having 90-40 weight percent of a second ethylene copolymer and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.0. The polyethylene composition contains 0.942 g / cm³ 3 Density above 5.0 g / 10 min, melt index I2 above 5.0 g / 10 min, melt flow ratio I2 below 50. 21 This is a solution-phase polymerization process having a ratio of / I2 and a long-chain branching coefficient LCBF of 0.0010 or greater.

[0018] One embodiment of the present disclosure is a rotationally molded article prepared from a polyethylene composition, (i) 0.880~0.930 g / cm³ 3Density, molecular weight distribution M (1.7-2.7) w / M n , and weight-average molecular weight M of 75,000 to 250,000 g / mol w A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945~0.965 g / cm³ 3 Density, molecular weight distribution M 2.0~3.5 w / M n , and weight-average molecular weight M of 15,000 to 75,000 g / mol w Having 90-40 weight percent of a second ethylene copolymer and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.0. The polyethylene composition contains 0.942 g / cm³ 3 Density above 5.0 g / 10 min, melt index I2 above 5.0 g / 10 min, melt flow ratio I2 below 50. 21 This is a rotationally molded product having / I2 and a long-chain branching coefficient LCBF of 0.0010 or greater. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 shows gel permeation chromatography (GPC-RI) results obtained for polyethylene compositions and comparative resins prepared according to this disclosure, using refractive index detection. [Figure 2]Figure 2 shows gel permeation chromatography obtained using Fourier transform infrared (GPC-FTIR) detection for polyethylene compositions and comparative resins prepared according to this disclosure. Comonomer content is shown as the number of short-chain branches per 1000 carbon atoms in the skeleton (y-axis) and in relation to the copolymer molecular weight (x-axis). The relatively upward-sloping line (from left to right) represents the short-chain branches determined by FTIR (short-chain branches per 1000 carbon atoms). As can be seen from Figure 2, in Invention Examples 1 to 6, the number of carbon branches increases with molecular weight, so it is said that the comonomer incorporation is "reversed". [Figure 3] Figure 3 shows the temperature rise elution fractionation (so-called "CTREF-SLOW") profile for polyethylene compositions prepared according to this disclosure. [Figure 4A] Figure 4A shows the viscosity profile obtained from a DMA frequency sweep experiment (viscosity η* (Pa·s) versus frequency ω (radians / s)) conducted at 190°C for a polyethylene composition prepared according to this disclosure. [Figure 4B] Figure 4B shows the viscosity profiles obtained from DMA frequency sweep experiments (viscosity η*(Pa·s) vs. frequency ω(radians / s)) conducted at 190°C for various comparative resins. [Figure 5] Figure 5 shows the powder densification characteristics of the polyethylene compositions of this disclosure and various comparative resins when used to produce rotationally molded parts. Figure 5 shows the delta density (defined as the plaque density minus the "original density") as a function of oven time (ARM impact tests were performed at -40°C using 1 / 4-inch rotationally molded test specimens prepared at an oven temperature of 560°F). [Figure 6] Figure 6 shows the ARM impact performance characteristics of the polyethylene compositions of this disclosure and various comparative resins when used to produce rotationally molded parts. Figure 6 shows the average fracture energy (ARM impact resistance) as a function of oven time (ARM impact tests were performed at -40°C using 1 / 4-inch rotationally molded test specimens prepared at an oven temperature of 560°F). [Figure 7A]Figure 7A shows the ductility performance characteristics of the polyethylene composition of this disclosure when used to produce rotationally molded parts. Figure 7A shows the ductility ratio with respect to oven time (ARM impact tests were performed at -40°C using 1 / 4-inch rotationally molded test specimens prepared at an oven temperature of 560°F). [Figure 7B] Figure 7B shows the ductility performance characteristics of various comparative resins when they are used to fabricate rotationally molded parts. Figure 7B shows the ductility ratio with respect to oven time (ARM impact tests were performed at -40°C using 1 / 4-inch rotationally molded specimens fabricated at an oven temperature of 560°F). [Figure 8A] Figure 8A shows the Van Gurp Palmen (VGP) plot for the polyethylene composition of this disclosure. The VGP plot was obtained from a DMA frequency sweep experiment conducted at 190°C. [Figure 8B] Figure 8B shows Van Gurp Palmen (VGP) plots for various comparative resins. The VGP plots were obtained from DMA frequency sweep experiments conducted at 190°C. [Modes for carrying out the invention]

[0020] It should be understood that any numerical range described herein is intended to include all subranges contained therein. For example, the range "1 to 10" is intended to include all subranges between the stated minimum value of 1 and the stated maximum value of 10, i.e., the minimum value is greater than or equal to 1 and the maximum value is less than or equal to 10. Since the disclosed numerical ranges are continuous, they include all values ​​between the minimum and maximum values.

[0021] As used herein, the term “monomer” refers to a small molecule that can react chemically and chemically bond with itself or other monomers to form polymers.

[0022] As used herein, the term "α-olefin" is used to describe monomers having a linear hydrocarbon chain containing 3 to 20 carbon atoms with a double bond at one end of the chain, and the equivalent term is "linear α-olefin".

[0023] The terms "ethylene homopolymer" or "polyethylene homopolymer" mean a product of a polymerization process in which ethylene alone was intentionally added or intentionally present as the polymerization monomer.

[0024] The terms "ethylene copolymer" or "polyethylene copolymer" mean a product of a polymerization process in which ethylene and one or more α-olefins were intentionally added or intentionally present as polymerizable monomers.

[0025] So-called "long chain branches" or "long chain branching" are macromolecular in nature and are distinguished from short chain branches because, for example, they can be as long as the polymer backbone (to which the long chain branches are attached).

[0026] As used herein, the term “unsubstituted” means that a hydrogen radical is bonded to the molecular group following the term “unsubstituted.” The term “substituted” means that the group following the term has one or more moieties (non-hydrogen radicals) that replace one or more hydrogen radicals at any position within the group.

[0027] This disclosure provides a polyethylene composition comprising two components: (i) a first ethylene copolymer, and (ii) a second ethylene copolymer different from the first ethylene copolymer.

[0028] In one embodiment of the present disclosure, the polyethylene composition is useful for manufacturing molded articles.

[0029] In one embodiment of the present disclosure, the polyethylene composition is useful for manufacturing rotationally molded articles.

[0030] In one embodiment of the present disclosure, the polyethylene composition is useful for manufacturing compression molded articles or injection molded articles.

[0031] <First ethylene copolymer> In one embodiment of the present disclosure, the first ethylene copolymer comprises both polymerized ethylene and at least one polymerized α-olefin comonomer, with polymerized ethylene making up the majority.

[0032] In embodiments of the present disclosure, the α-olefin that can copolymerize with ethylene to produce a first ethylene copolymer may be selected from the group comprising 1-propene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and mixtures thereof.

[0033] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site catalyst, non-limiting examples of which include phosphine imine catalysts, metallocene catalysts, and constrained geometric catalysts, all of which are well known in the art.

[0034] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site polymerization catalyst in a solution-phase polymerization process.

[0035] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site catalyst having hafnium (Hf) as the active metal center.

[0036] In one embodiment of the present disclosure, the first ethylene copolymer is an ethylene / 1-octene copolymer.

[0037] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a metallocene catalyst.

[0038] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a crosslinked metallocene catalyst.

[0039] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a crosslinked metallocene catalyst having formula (I): [ka]

[0040] In formula (I), M is a group 4 metal selected from titanium, zirconium, or hafnium; G is a group 14 element selected from carbon, silicon, germanium, tin, or lead; R1 is a hydrogen atom, C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radicals, or C 6-10 It is an aryl oxide radical; R2 and R3 are hydrogen atoms, C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radical or C 6-10 Independently selected from aryl oxide radicals; R4 and R5 are hydrogen atoms, unsubstituted C 1-20 Hydrocarbyl radical, substituted C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radical or C 6-10 It is independently selected from the aryl oxide radical; Q is independently an activatable leaving ligand.

[0041] In one embodiment, G is carbon.

[0042] In one embodiment, R4 and R5 are independently aryl groups. In one embodiment, R4 and R5 are independently a phenyl group or a substituted phenyl group. In one embodiment, R4 and R5 are phenyl groups. In one embodiment, R4 and R5 are independently substituted phenyl groups. In one embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with substituted silyl groups. In one embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with trialkylsilyl groups. In one embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with a trialkylsilyl group at the para position. In another embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with a trimethylsilyl group at the para position. In yet another embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with a triethylsilyl group at the para position. In one embodiment, R4 and R5 are independently alkyl groups. In one embodiment, R4 and R5 are independently alkenyl groups.

[0043] In one embodiment, R1 is hydrogen. In one embodiment, R1 is an alkyl group. In one embodiment, R1 is an aryl group. In one embodiment, R1 is an alkenyl group.

[0044] In one embodiment, R2 and R3 are independently hydrocarbyl groups having 1 to 30 carbon atoms. In one embodiment, R2 and R3 are independently aryl groups. In one embodiment, R2 and R3 are independently alkyl groups. In one embodiment, R2 and R3 are independently alkyl groups having 1 to 20 carbon atoms. In one embodiment, R2 and R3 are independently a phenyl group or a substituted phenyl group. In one embodiment, R2 and R3 are tert-butyl groups. In one embodiment, R2 and R3 are hydrogen.

[0045] In one embodiment, M is hafnium (Hf).

[0046] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a crosslinked metallocene catalyst having formula (I): [ka]

[0047] In formula (I), G is a Group 14 element selected from carbon, silicon, germanium, tin, or lead; R1 is a hydrogen atom, C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radicals, or C 6-10 It is an aryl oxide radical; R2 and R3 are hydrogen atoms, C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radical or C 6-10 Independently selected from aryl oxide radicals; R4 and R5 are hydrogen atoms, unsubstituted C 1-20 Hydrocarbyl radical, substituted C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radical or C 6-10 It is independently selected from the aryl oxide radical; Q is independently an activatable leaving ligand.

[0048] In this disclosure, the term “activatable” means that ligand Q can be cleaved from a metal center M via a protonolysis reaction, or abstracted from a metal center M by a suitable acidic or electrophilic catalytic compound (also known as a “cocatalytic” compound), examples of which are described below. Activatable ligand Q can also be converted to another ligand that is cleaved or abstracted from a metal center M (for example, a halide can be converted to an alkyl group). While we do not wish to be bound by a single theory, protonolysis or abstraction reactions generate an active “cationic” metal center capable of polymerizing olefins.

[0049] In embodiments of this disclosure, the activatable ligand Q is independently selected from the group consisting of: hydrogen atoms; halogen atoms; C 1~20 Hydrocarbyl radical, C 1~20 Alkoxy radicals, and C 6-10Aryl or aryloxy radical, where each of the hydrocarbyl, alkoxy, aryl, or aryloxy radicals may be unsubstituted or further substituted with one or more halogens or other groups; C 1-8 Alkyl; C 1-8 Alkoxy; C 6-10 Q is an aryl or aryloxy; an amide or phosphide radical, but Q is not a cyclopentadienyl. Alternatively, two Q ligands may bond to each other to form, for example, a substituted or unsubstituted diene ligand (e.g., 1,3-butadiene); or a delocalized heteroatom-containing group such as an acetate or acetamidinate group. In a convenient embodiment of this disclosure, each Q is a halide atom, C 1~4 The ligand Q is independently selected from the group consisting of alkyl radicals and benzyl radicals. Particularly suitable activatable ligands Q are monoanionic, such as halides (e.g., chlorides) or hydrocarbyls (e.g., methyl, benzyl).

[0050] In one embodiment of the present disclosure, the single-site catalyst used to produce the first ethylene copolymer is diphenylmethylene(cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dichloride having the following molecular formula: [(2,7-tBu2Flu)Ph2C(Cp)HfCl2].

[0051] In one embodiment of this disclosure, the single-site catalyst used to produce the first ethylene copolymer is diphenylmethylene(cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafniumdimethyl having the following molecular formula: [(2,7-tBu2Flu)Ph2C(Cp))HfMe2].

[0052] In addition to the single-site catalyst molecule itself, the active single-site catalyst system may further include one or more of the following: an alkylaluminoxane cocatalyst and an ionic activator. The single-site catalyst system may also optionally include a hindered phenol.

[0053] Although the precise structure of alkylaluminoxanes is unknown, experts in the field generally agree that they are oligomeric species containing repeating units of the following general formula: (R)2AlO-(Al(R)-O) n -Al(R)2 (wherein the formula, the R group may be the same or different linear, branched, or cyclic hydrocarbyl radicals containing 1 to 20 carbon atoms, and n is 0 to about 50). A non-limiting example of alkylaluminoxane is methylaluminoxane (or MAO), where each R group is a methyl radical.

[0054] In one embodiment of the present disclosure, R of the alkylaluminoxane is a methyl radical, and m is 10 to 40.

[0055] In one embodiment of this disclosure, the cocatalyst is a modified methylaluminoxane (MMAO).

[0056] It is well known in the art that alkylaluminoxanes can play a dual role as both alkylating and activating agents. Therefore, alkylaluminoxane cocatalysts are often used in combination with activatable ligands such as halogens.

[0057] Generally, ionic surfactants consist of a cation and a bulky anion, the latter being substantially non-coordinating. A non-limiting example of an ionic surfactant is a four-coordinating boron ionic surfactant, which has four ligands bonded to the boron atom. Several formulas are shown below as non-limiting examples of boron ionic surfactants: [R 5 ] + [B(R 7 )4] - (In the formula, B represents a boron atom, and R 5 is an aromatic hydrocarbyl (e.g., triphenylmethyl cation), and each R 7This is independently selected from the following: a phenyl radical substituted with 3 to 5 substituents selected from unsubstituted or fluorine atoms, or a C substituted with unsubstituted or fluorine atoms. 1~4 Alkyl or alkoxy radicals, and formula -Si(R 9 )3 silyl radicals, where each R 9 is a hydrogen atom and C 1-4 (Selected independently of alkyl radicals), and [(R 8 ) t ZH] + [B(R 7 )4] - (In the formula, B is a boron atom, H is a hydrogen atom, Z is a nitrogen or phosphorus atom, t is 2 or 3, R 8 C 1~8 alkyl radicals, unsubstituted or up to 3 C 1-4 Selected from phenyl radicals substituted with alkyl radicals, or one R 8 R may form an anilinium radical together with the nitrogen atom, 7 (This is defined above).

[0058] In both equations, R 7A non-limiting example is the pentafluorophenyl radical. In general, boron ionic surfactants can be described as salts of tetra(perfluorophenyl)boron, and non-limiting examples include anilinium, carbonium, oxonium, phosphonium, and sulfonium salts of tetra(perfluorophenyl)boron with anilinium and trityl (or triphenylmethylium). Non-limiting examples of additional ionic surfactants include triethylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(m,m-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tri(n-butyl)ammonium tetra(o-tolyl)boron, N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)boron, and N,N-diethylanilinium N,N-2,4,6-Pentamethylanilinium tetra(phenyl)boron, di-(isopropyl)ammonium tetra(pentafluorophenyl)boron, dicyclohexylammonium tetra(phenyl)boron, triphenylphosphonium tetra(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron, tri(dimethylphenyl)phosphonium tetra(phenyl)boron, tropylium tetrakisspentafluorophenyl borate, triphenylmethylium tetrakisspentafluorophenyl borate, benzene(diazonium) tetrakisspentafluorophenyl borate, tropylium tetrakis(2,3,5,6-tetrafluorophenyl) borate, triphenylmethylium tetrakis(2,3,5,6-tetrafluorophenyl) borate, benzene(diazonium) tetrakis(3,4,Examples include 5-trifluorophenyl) borate, tropylium tetrakis(3,4,5-trifluorophenyl) borate, benzene(diazonium) tetrakis(3,4,5-trifluorophenyl) borate, tropylium tetrakis(1,2,2-trifluoroethenyl) borate, triphenylmethylium tetrakis(1,2,2-trifluoroethenyl) borate, benzene(diazonium) tetrakis(1,2,2-trifluoroethenyl) borate, tropylium tetrakis(2,3,4,5-tetrafluorophenyl) borate, triphenylmethylium tetrakis(2,3,4,5-tetrafluorophenyl) borate, and benzene(diazonium) tetrakis(2,3,4,5-tetrafluorophenyl) borate. Easily available commercial ionic surfactants include N,N-dimethylanilinium tetrakispentafluorophenyl borate and triphenylmethylium tetrakispentafluorophenyl borate.

[0059] Non-limiting examples of hindered phenols include butylated phenol antioxidants, butylated hydroxytoluene, 2,6-di-tert-butyl-4-ethylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate.

[0060] To generate an active metallocene-based catalytic system, the amounts and molar ratios of three or four components—a metallocene single-site catalyst, an alkylaluminoxane, an ionic activator, and an optional hindered phenol—are optimized.

[0061] In one embodiment of the present disclosure, a single-site catalyst used to produce a first ethylene copolymer generates long-chain branching, and the first ethylene copolymer contains long-chain branching (hereinafter referred to as "LCB").

[0062] Long chain branching (LCB) is a well-known structural phenomenon in ethylene copolymers and is well known to those skilled in the art. Conventionally, there are three methods for LCB analysis: nuclear magnetic resonance (NMR) spectroscopy (see, e.g., J. C Randall, J. Macromol. Sci., Rev., Macromol. Chem. Phys., 1989, Vol. 29, p. 201); triple-detection SEC with DRI, viscometer, and low-angle laser light scattering detector (see, e.g., W. W. Yau and D. Hill, Int. J. Polym. Anal. Character., 1996, Vol. 2, p. 151); and rheology (see, e.g., W. W. Graessley, Acc. Chem. Res., 1977, Vol. 10, pp. 332-339). In embodiments of this disclosure, the long chain branching is essentially macromolecule, i.e., long enough to be observed in NMR spectra, triple-detector SEC experiments, or rheological experiments.

[0063] In one embodiment of the present disclosure, the first ethylene copolymer includes long-chain branching characterized by the long-chain branching coefficient LCBF disclosed herein. In embodiments of the present disclosure, the upper limit of the LCBF of the first ethylene copolymer may be 0.5000, 0.4000, or 0.3000 (dimensionless). In embodiments of the present disclosure, the lower limit of the LCBF of the first ethylene copolymer may be 0.0010, 0.0015, 0.0020, 0.0050, 0.0070, 0.0100, 0.0500, or 0.1000 (dimensionless).

[0064] In embodiments of the present disclosure, the LCBF of the first ethylene copolymer is at least 0.0010, or at least 0.0020, or at least 0.0050, or at least 0.0070, or at least 0.0100.

[0065] The first ethylene copolymer may contain catalyst residues that reflect the chemical composition of the catalyst formulation used to produce it. Those skilled in the art will understand that catalyst residues are typically quantified by parts per million of metal in the first ethylene copolymer (or polyethylene composition; see below), where the metals present are derived from the metals in the catalyst formulation used to produce it. Non-limiting examples of metal residues that may be present include Group IV metals, titanium, zirconium, and hafnium. In embodiments of the present disclosure, the upper limit of the ppm of metal in the first ethylene copolymer may be about 3.0 ppm, in other cases about 2.0 ppm, and in yet other cases about 1.5 ppm. In embodiments of the present disclosure, the lower limit of the ppm of metal in the first ethylene copolymer may be about 0.03 ppm, in other cases about 0.09 ppm, and in yet other cases about 0.15 ppm.

[0066] In one embodiment of the present disclosure, the first ethylene copolymer has 1 to 100 short-chain branches (SCB1) per 1000 carbon atoms. In a further embodiment, the first ethylene copolymer has 3 to 100 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 100 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 75 short-chain branches (SCB1) per 1000 carbon atoms, or 10 to 75 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 50 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 30 short-chain branches per 1000 carbon atoms, or 100 It has 10 to 50 short-chain branches (SCB1) per 0 carbon atoms, or 15 to 75 short-chain branches (SCB1) per 1000 carbon atoms, or 3 to 50 short-chain branches (SCB1) per 1000 carbon atoms, or 7.5 to 50 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 40 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 30 short-chain branches (SCB1) per 1000 carbon atoms, or 5 to 25 short-chain branches (SCB1) per 1000 carbon atoms.

[0067] Short-chain branches (i.e., short-chain branches per 1000 skeletal carbon atoms, SCB1) are branches due to the presence of α-olefin comonomers in the ethylene copolymer. For example, in the case of a 1-butene comonomer, it has 2 carbon atoms; in the case of a 1-hexene comonomer, it has 4 carbon atoms; in the case of a 1-octene comonomer, it has 6 carbon atoms, etc.

[0068] In one embodiment of the present disclosure, the number of short-chain branches per 1000 carbon atoms (SCB1) in the first ethylene copolymer is greater than the number of short-chain branches per 1000 carbon atoms (SCB2) in the second ethylene copolymer.

[0069] In one embodiment of the present disclosure, the density of the first copolymer is less than the density of the second ethylene copolymer.

[0070] In one embodiment of the present disclosure, the first ethylene copolymer has a density of 0.865 to 0.930 g / cm 3 and includes any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the first ethylene copolymer has a density of 0.880 to 0.930 g / cm 3 or 0.880 to 0.928 g / cm 3 or 0.880 to 0.926 g / cm 3 or 0.890 to 0.928 g / cm 3 or 0.890 to 0.926 g / cm 3 or 0.890 to 0.925 g / cm 3 or 0.890 to 0.922 g / cm 3 or 0.890 to 0.920 g / cm 3 or 0.880 to 0.919 g / cm 3 or 0.880 to 0.918 g / cm 3 or 0.880 to 0.916 g / cm 3 or 0.880 to 0.912 g / cm 3 or 0.880 to 0.910 g / cm 3 or 0.880 to 0.909 g / cm 3 or 0.880 to 0.908 g / cm 3, or 0.890 - 0.920 g / cm 3 , or 0.890 - 0.919 g / cm 3 , or 0.890 - 0.918 g / cm 3 , or 0.890 - 0.916 g / cm 3 , or 0.890 - 0.912 g / cm 3 , or 0.890 - 0.910 g / cm 3 , or 0.890 - 0.909 g / cm 3 , or 0.890 - 0.908 g / cm 3 , or 0.900 - 0.920 g / cm 3 , or 0.900 - 0.919 g / cm 3 , or 0.900 - 0.918 g / cm 3 , or 0.900 - 0.916 g / cm 3 , or 0.900 - 0.912 g / cm 3 , or 0.900 - 0.910 g / cm 3 , or 0.900 - 0.909 g / cm 3 , or 0.900 - 0.908 g / cm 3 has a density of

[0071] In one embodiment of the present disclosure, the first ethylene copolymer has a density of less than 0.880 - 0.920 g / cm 3 less than

[0072] In an embodiment of the present disclosure, the first ethylene copolymer has a density of less than 0.880 - 0.918 g / cm 3 , or less than 0.880 - 0.910 g / cm 3 less than

[0073] In one embodiment of the present disclosure, the first ethylene copolymer has a density of less than 0.918 g / cm 3 , or less than 0.910 g / cm 3 less than

[0074] In one embodiment of the present disclosure, the melt index I2 of the first ethylene copolymer is less than the melt index I2 of the second ethylene copolymer.

[0075] In embodiments of the present disclosure, the first ethylene copolymer has a melt index I2 of 10 g / 10 min or less, or 5.0 g / 10 min or less, or 2.5 g / 10 min or less, or 1.0 g / 10 min or less, or less than 1.0 g / 10 min. In another embodiment of the present disclosure, the first ethylene copolymer has a melt index I2 of 0.001 to 10.0 g / 10 min, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the melt index I2 of the first ethylene copolymer is 0.001 to 7.5 g / 10 min, or 0.001 to 5.0 g / 10 min, or 0.001 to 2.5 g / 10 min, or 0.001 to 1.0 g / 10 min, or 0.01 to 10.0 g / 10 min, or 0.01 to 7.5 g / 10 min, or 0. It may be 0.1-5.0g / 10 min, or 0.01-2.5g / 10 min, or 0.01-1.0g / 10 min, or 0.1-10.0g / 10 min, or 0.1-7.5g / 10 min, or 0.1-5.0g / 10 min, or 0.1-2.5g / 10 min, or 0.1-1.0g / 10 min, or less than 0.1-1.0g / 10 min.

[0076] In one embodiment of the present disclosure, the first ethylene copolymer has a weight-average molecular weight M of 75,000 to 300,000 g / mol. w It has a weight-average molecular weight M of 75,000 to 250,000 g / mol, or 100,000 to 250,000 g / mol, or 100,000 to 225,000 g / mol, or 100,000 to 200,000 g / mol, or 125,000 to 200,000 g / mol, or 125,000 to 180,000 g / mol. w It has.

[0077] In one embodiment of the present disclosure, the first ethylene copolymer has a melt flow ratio I of less than 25, less than 23, or less than 20. 21 It has / I2.

[0078] In embodiments of this disclosure, the molecular weight distribution M of the first ethylene copolymer w / M n The upper limit may be about 2.7, or about 2.5, or about 2.4, or about 2.3, or about 2.2. In embodiments of the present disclosure, the molecular weight distribution M of the first ethylene copolymer w / M n The lower limit may be approximately 1.6, or approximately 1.7, or approximately 1.8, or approximately 1.9.

[0079] In embodiments of this disclosure, the first ethylene copolymer has a molecular weight distribution of 3.0 or less, or less than 3.0, or 2.7 or less, or less than 2.7, or 2.5 or less, or less than 2.5, or 2.3 or less, or less than 2.3, or 2.1 or less, or less than 2.1, or about 2. w / M n It has. In another embodiment of the present disclosure, the first ethylene copolymer has a molecular weight distribution M of 1.7 to 3.0. w / M n It has a molecular weight distribution M of 1.7-2.7, or 1.8-2.7, or 1.8-2.5, or 1.8-2.3, or 1.9-2.2, or 1.9-2.1. w / M n It has.

[0080] In embodiments of this disclosure, the CDBI of the first ethylene copolymer 50 The upper limit may be about 98% by weight, in other cases about 95 wt%, and in yet other cases about 90 wt%. In embodiments of the present disclosure, the CDBI of the first ethylene copolymer 50 The lower limit may be about 70% by weight, or in other cases about 75% by weight, or in yet other cases about 80% by weight.

[0081] In one embodiment of the present disclosure, at least 65% by weight, or at least 70% by weight, or at least 75% by weight, or at least 80% by weight, or at least 85% by weight of CDBI during solution phase polymerization in a single reactor.50 A single-site catalyst that yields an ethylene copolymer having [a specific characteristic] is used in the preparation of the first ethylene copolymer.

[0082] In embodiments of the present disclosure, the first ethylene copolymer is CDBI in an amount exceeding about 60% by weight, or exceeding about 65% by weight, or exceeding about 70% by weight, or exceeding about 75% by weight, or exceeding about 80% by weight, or exceeding about 85% by weight. 50 It is an ethylene copolymer having [a certain characteristic].

[0083] In embodiments of the present disclosure, the weight percentage (wt%) of the first ethylene copolymer in the polyethylene composition (i.e., the weight percentage of the first ethylene copolymer based on the total weight of the first and second ethylene copolymers) may be about 5 wt% to about 75 wt%, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the weight percentage (wt%) of the first ethylene copolymer in the polyethylene copolymer composition may be about 5 wt% to about 65 wt%, or about 10 wt% to about 60 wt%, or about 10 wt% to about 50 wt%, or about 10 wt% to about 45 wt%, or about 10 wt% to about 40 wt%, or about 15 wt% to about 50 wt%, or about 15 wt% to about 40 wt%, or about 20 wt% to about 40 wt%, or about 20 wt% to about 35 wt%.

[0084] <Second Ethylene Copolymer> In one embodiment of the present disclosure, the second ethylene copolymer is prepared using a multi-site catalyst system, non-limiting examples of which include Ziegler-Natta catalysts and chromium catalysts, both of which are well known in the art.

[0085] In embodiments of the present disclosure, the alpha-olefin that can copolymerize with ethylene to produce a second ethylene copolymer may be selected from the group comprising 1-propene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and mixtures thereof.

[0086] In one embodiment of the present disclosure, the second ethylene copolymer is a heterogeneously branched ethylene copolymer.

[0087] In one embodiment of the present disclosure, the second ethylene copolymer is an ethylene / 1-octene copolymer.

[0088] In one embodiment of the present disclosure, the second ethylene copolymer is prepared using a Ziegler-Natta catalyst system.

[0089] The Ziegler-Natta catalyst system is well known to those skilled in the art. The Ziegler-Natta catalyst may be an in-line Ziegler-Natta catalyst system or a batch Ziegler-Natta catalyst system. The term "in-line Ziegler-Natta catalyst system" refers to the continuous synthesis of a small amount of activated Ziegler-Natta catalyst system and the immediate injection of this catalyst into at least one continuous-operating reactor, where the catalyst polymerizes ethylene with one or more optionally selected α-olefins to form an ethylene polymer. The terms "batch Ziegler-Natta catalyst system" or "batch Ziegler-Natta pro-catalyst" refer to the synthesis of a much larger amount of catalyst or pro-catalyst in one or more mixing vessels, either outside or separated from a continuously operating solution polymerization process. The prepared batch catalyst Ziegler-Natta catalyst system, or batch Ziegler-Natta pro-catalyst, is transferred to a catalyst storage tank. The term "procatalyst" refers to an inert catalyst system (inert with respect to ethylene polymerization), which is converted into an active catalyst by the addition of an alkylaluminum cocatalyst. If necessary, the procatalyst is pumped from a storage tank to at least one continuous-operation reactor, where the active catalyst polymerizes ethylene and one or more optionally selected α-olefins to form an ethylene copolymer. The procatalyst may be converted into an active catalyst in the reactor, outside the reactor, or en route to the reactor.

[0090] A wide variety of compounds can be used to synthesize an activated Ziegler-Natta catalyst system. The following describes various compounds that can be combined to produce an activated Ziegler-Natta catalyst system. Those skilled in the art will understand that the embodiments described herein are not limited to the specific compounds disclosed.

[0091] The activated Ziegler-Natta catalyst system can be formed from magnesium compounds, chloride compounds, metal compounds, alkylaluminum co-catalysts, and aluminum alkyls. As will be understood by those skilled in the art, the Ziegler-Natta catalyst system may also contain additional components, non-limiting examples of which are electron donors, such as amines or ethers.

[0092] Non-limiting examples of active in-line (or batch) Ziegler-Natta catalyst systems can be prepared as follows: In the first step, a solution of a magnesium compound is reacted with a solution of a chloride compound to form a magnesium chloride support suspended in solution. Non-limiting examples of magnesium compounds include Mg(R) 1 )2 is given, and in the formula, R 1 The groups may be the same or different, and may be linear, branched, or cyclic hydrocarbyl radicals containing 1 to 10 carbon atoms. Non-limiting examples of chloride compounds include R 2 Cl is mentioned, and in the formula, R 2 represents a linear, branched, or cyclic hydrocarbyl radical containing a hydrogen atom or 1 to 10 carbon atoms. In the first step, the solution of the magnesium compound may contain an aluminum alkyl group. Non-limiting examples of aluminum alkyl groups include Al(R 3 )3 is given, and in the formula, R 3 The groups may be the same or different, and may be linear, branched, or cyclic hydrocarbyl radicals containing 1 to 10 carbon atoms. In the second step, a solution of the metal compound is added to a solution of magnesium chloride to support the metal compound on the magnesium chloride. A non-limiting example of a suitable metal compound is M(X) n or MO(X)n Examples include the following formulas, where M represents a metal selected from groups 4-8 of the periodic table, or a mixture of metals selected from groups 4-8; O represents oxygen; X represents a chloride or bromide; and n is an integer from 3 to 6 that satisfies the oxidation state of the metal. Additional non-limiting examples of suitable metal compounds include group 4-8 metal alkyls, metal alkoxides (which can be prepared by reacting a metal alkyl with an alcohol), and mixed ligand metal compounds including halides, alkyl and alkoxide ligands. In the third step, a solution of the alkylaluminum cocatalyst is added to the metal compound supported on magnesium chloride. A wide variety of alkylaluminum cocatalysts are suitable, as shown in the following formula: Al(R 4 ) p (OR 9 ) q (X) r (In the formula, R 4 The groups may be the same or different, and may be hydrocarbyl groups having 1 to 10 carbon atoms, OR 9 The groups may be the same or different, and may be an alkoxy group or an aryloxy group, R 9 X is a hydrocarbyl group having 1 to 10 carbon atoms bonded to oxygen, where X is a chloride or bromide, and (p+q+r)=3, where p is greater than 0. Non-limiting examples of commonly used alkylaluminum cocatalysts include trimethylaluminum, triethylaluminum, tributylaluminum, dimethylaluminum methoxide, diethylaluminum ethoxide, dibutylaluminum butoxide, dimethylaluminum chloride or bromide, diethylaluminum chloride or bromide, dibutylaluminum chloride or bromide, and ethylaluminum dichloride or dibromide.

[0093] The process described in the above paragraph for synthesizing an active in-line (or batch) Ziegler-Natta catalyst system can be carried out in a variety of solvents, and non-limiting examples of solvents include linear or branched C5-C12 Examples include alkanes or mixtures thereof.

[0094] In one embodiment of the present disclosure, the short-chain branching in the second ethylene copolymer can be such that the branching ratio per 1000 carbon atoms (SCB2 / 1000C) is about 0.10 to about 10.0. In a further embodiment of the present disclosure, the short-chain branching in the second ethylene copolymer can be such that the branching ratio per 1000 carbon atoms (SCB2 / 1000C) is 0.10 to 7.5, or 0.10 to 5.0, or 0.10 to 3.0, or 0.10 to 1.5.

[0095] Short-chain branching (i.e., short-chain branching per 1000 carbon atoms in the backbone, SCB2) is branching caused by the presence of α-olefin comonomers in ethylene copolymers. For example, 1-butene comonomers have 2 carbon atoms, 1-hexene comonomers have 4 carbon atoms, and 1-octene comonomers have 6 carbon atoms.

[0096] In one embodiment of the present disclosure, the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer (SCB2) is less than the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1).

[0097] In one embodiment of the present disclosure, the density of the second copolymer is greater than the density of the first ethylene copolymer.

[0098] In one embodiment of this disclosure, the second ethylene copolymer is 0.945 to 0.975 g / cm³. 3 It has a density of 0.945 to 0.970 g / cm³, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the second ethylene copolymer has a density of 0.945 to 0.970 g / cm³. 3 , or 0.945~0.965 g / cm³ 3 , or 0.945~0.963 g / cm³ 3 , or 0.945~0.962 g / cm³ 3 , or 0.950~0.970 g / cm³ 3, or 0.950~0.965 g / cm³ 3 , or 0.950~0.963 g / cm³ 3 , or 0.950~0.962 g / cm³ 3 , or 0.952~0.970 g / cm³ 3 , or 0.952~0.965 g / cm³ 3 , or 0.952~0.963 g / cm³ 3 , or 0.952~0.962 g / cm³ 3 , or 0.955~0.975 g / cm³ 3 , or 0.955~0.972 g / cm³ 3 , or 0.955~0.970 g / cm³ 3 , or 0.955~0.965 g / cm³ 3 , or 0.955~0.963 g / cm³ 3 , or 0.955~0.962 g / cm³ 3 It has a density of .

[0099] In one embodiment of this disclosure, the melt index I2 of the second ethylene copolymer is greater than the melt index I2 of the first ethylene copolymer.

[0100] In one embodiment of the present disclosure, the second ethylene copolymer has a melt index I2 of 20.0 g / 10 min or more.

[0101] In one embodiment of the present disclosure, the second ethylene copolymer has a melt index I2 of 50.0 g / 10 min or more.

[0102] In embodiments of the present disclosure, the second ethylene copolymer has a melt index I2 of 10 to 5000, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the melt index I2 of the second ethylene copolymer is 10 to 2,500 g / 10 min, or 15 to 2,500 g / 10 min, or 20 to 5,000 g / 10 min, or 20 to 2,500 g / 10 min, or 50 to 5,000 g / 10 min, or 50 to 2,500 g / 10 min, or 20 to 1,000 g / 10 min, or 50 to 1,000 g / 10 min, or 20 to 500 g / 10 min, or 50 to 500 g / 10 min, or 20 to 250 g / 10 min, or 50 to 250 g / 10 min. In other embodiments of the present disclosure, the melt index I2 of the second ethylene copolymer is 10-150 g / 10 min, or 15-150 g / 10 min, or 20-150 g / 10 min, or 20-100 g / 10 min, or 20-75 g / 10 min.

[0103] In one embodiment of the present disclosure, the second ethylene copolymer has a weight-average molecular weight M of 75,000 g / mol or less, or 60,000 g / mol or less, or 50,000 g / mol or less, or 45,000 g / mol or less, or 40,000 g / mol or less, or 35,000 g / mol or less, or 30,000 g / mol or less. w In another embodiment, the second ethylene copolymer has a weight-average molecular weight M of 5,000 to 75,000 g / mol. w It has a weight-average molecular weight M of 10,000 to 75,000 g / mol, or 15,000 to 75,000 g / mol, or 15,000 to 65,000 g / mol, or 15,000 to 60,000 g / mol, or 15,000 to 50,000 g / mol, or 20,000 to 60,000 g / mol, or 20,000 to 55,000 g / mol, or 20,000 to 50,000 g / mol, or 20,000 to 45,000 g / mol, or 20,000 to 40,000 g / mol. w It has.

[0104] In one embodiment of the present disclosure, the weight-average molecular weight (M) of the second ethylene copolymer is w ) is the weight-average molecular weight (M) of the first ethylene copolymer. w It is lower than ).

[0105] In embodiments of the present disclosure, the second ethylene copolymer has a molecular weight distribution M of 2.1 or more, or greater than 2.1, or greater than 2.2, or greater than 2.2, or greater than 2.3, or greater than 2.3, or greater than 2.5, or greater than 2.7, or greater than 2.7, or greater than 2.9, or greater than 2.9, or greater than 3.0, or greater than 3.0. w / M n In embodiments of the present disclosure, the second ethylene copolymer has a molecular weight distribution M of 2.3-6.0, or 2.3-5.5, or 2.3-5.0, or 2.3-4.5, or 2.3-4.0, or 2.3-3.5, or 2.3-3.0, or 2.5-5.0, or 2.5-4.5, or 2.5-4.0, or 2.5-3.5, or 2.7-5.0, or 2.7-4.5, or 2.7-4.0, or 2.7-3.5, or 2.1-3.5, or 2.2-3.5. w / M n It has.

[0106] In one embodiment of the present disclosure, less than 60% by weight or less than 50 wt% of CDBI is added during solution-phase polymerization in a single reactor. 50 A multi-site catalyst that yields an ethylene copolymer having [a specific characteristic] is used to prepare a second ethylene copolymer.

[0107] In embodiments of the present disclosure, the weight percentage (wt%) of the second ethylene copolymer in the polyethylene composition (i.e., the weight percentage of the second ethylene copolymer based on the total weight of the first and second ethylene copolymers) may be about 95 wt% to about 25 wt%, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the weight percentage (wt%) of the second ethylene copolymer in the polyethylene copolymer composition may be about 95 wt% to about 35 wt%, or about 90 wt% to about 40 wt%, or about 90 wt% to about 50 wt%, or about 90 wt% to about 55 wt%, or about 90 wt% to about 60 wt%, or about 85 wt% to about 50 wt%, or about 85 wt% to about 60 wt%, or about 80 wt% to about 60 wt%, or about 80 wt% to about 65 wt%.

[0108] <Polyethylene composition> In one embodiment of the present disclosure, the polyethylene composition comprises a first ethylene copolymer and a second ethylene copolymer (as defined above).

[0109] The polyethylene compositions disclosed herein can be prepared using any known techniques in the art, including, but not limited to, melt blends, solution blends, or reactor blends for combining a first ethylene copolymer with a second ethylene copolymer.

[0110] In one embodiment, the polyethylene composition of the present disclosure is prepared by producing a first ethylene copolymer using a single-site catalyst in a first reactor and a second ethylene copolymer using a multi-site catalyst in a second reactor.

[0111] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin in a first reactor using a single-site catalyst to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin in a second reactor using a multi-site catalyst to form a second ethylene copolymer.

[0112] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin using a single-site catalyst in a first solution-phase polymerization reactor to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin using a multi-site catalyst in a second solution-phase polymerization reactor to form a second ethylene copolymer.

[0113] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin using a single-site catalyst in a first solution-phase polymerization reactor to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin using a multi-site catalyst in a second solution-phase polymerization reactor to form a second ethylene copolymer, wherein the first and second solution-phase polymerization reactors are configured in series with respect to each other.

[0114] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin using a single-site catalyst in a first solution-phase polymerization reactor to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin using a multi-site catalyst in a second solution-phase polymerization reactor to form a second ethylene copolymer, wherein the first and second solution-phase polymerization reactors are configured in parallel with each other.

[0115] In this embodiment, the solution-phase polymerization reactor used as the first solution-phase reactor is a continuous-stirred tank reactor or a tubular reactor.

[0116] In one embodiment, the solution-phase polymerization reactor used as the second solution-phase reactor is a continuous-stirred tank reactor or a tubular reactor.

[0117] In solution polymerization, monomers are dissolved / dispersed in the solvent before being supplied to the reactor (or, in the case of gaseous monomers, the monomers may be supplied to the reactor and dissolved in the reaction mixture). Before mixing, the solvent and monomers are generally purified to remove potential catalyst poisons such as water, oxygen, and metal impurities. Purification of the feedstock follows standard practices in the art. For example, molecular sieves, alumina beds, and oxygen removal catalysts are used for the purification of monomers. It is also preferable to treat the solvent itself (e.g., methylpentane, cyclohexane, hexane, or toluene) in the same manner.

[0118] The raw materials may be heated or cooled before being supplied to the reactor.

[0119] Generally, catalyst components may be pre-mixed in the reaction solvent or supplied to the reactor as separate streams. In some cases, it may be desirable to pre-mix the catalyst components before they enter the polymerization reaction zone to ensure sufficient reaction time. Such "in-line mixing" techniques are well known to those skilled in the art.

[0120] Solution polymerization processes for the polymerization or copolymerization of ethylene are well known in the art (see, for example, U.S. Patents 6,372,864 and 6,777,509). These processes are carried out in the presence of an inert hydrocarbon solvent. In solution-phase polymerization reactors, a variety of solvents can be used as process solvents, and non-limiting examples include linear, branched, or cyclic C5-C5 polymers. 12 Alkanes are an example. Suitable catalytic solvents include aliphatic and aromatic hydrocarbons. Non-limiting examples of aliphatic catalytic solvents include linear, branched, or cyclic C5-C5 12Aliphatic hydrocarbons include, for example, pentane, methylpentane, hexane, heptane, octane, cyclohexane, cyclopentane, methylcyclohexane, naphtha hydrogenates, or combinations thereof. Non-limiting examples of aromatic catalyst solvents include benzene, toluene (methylbenzene), ethylbenzene, o-xylene (1,2-dimethylbenzene), m-xylene (1,3-dimethylbenzene), p-xylene (1,4-dimethylbenzene), mixtures of xylene isomers, hemeritene (1,2,3-trimethylbenzene), pseudocumene (1,2,4-trimethylbenzene), mesitylene (1,3,5-trimethylbenzene), mixtures of trimethylbenzene isomers, prehenytene (1,2,3,4-tetramethylbenzene), durene (1,2,3,5-tetramethylbenzene), mixtures of tetramethylbenzene isomers, pentamethylbenzene, hexamethylbenzene, and combinations thereof.

[0121] The polymerization temperature in a conventional solution process may be about 80°C to about 300°C. In one embodiment of the present disclosure, the polymerization temperature in the solution process is about 120°C to about 250°C. The polymerization pressure in the solution process may be a “medium-pressure process,” meaning that the pressure in the reactor is less than about 6,000 psi (about 42,000 kilopascals or kPa). In one embodiment of the present disclosure, the polymerization pressure in the solution process may be about 10,000 to about 40,000 kPa, or about 14,000 to about 22,000 kPa (i.e., about 2,000 psi to about 3,000 psi).

[0122] Suitable comonomers (i.e., α-olefins) for copolymerization with ethylene in solution-phase polymerization processes include C 3-20 This includes monoolefins and diolefins. In embodiments of this disclosure, comonomers copolymerizable with ethylene are unsubstituted or contain up to two C molecules. 1-6 C substituted with alkyl radicals 3-12 α-olefin, unsubstituted or C 1-4 C is substituted with up to two substituents selected from the group consisting of alkyl radicals.8-12 Vinyl aromatic monomers, unsubstituted or C 1-4 C substituted with alkyl radicals 4-12 This includes linear or cyclic diolefins. In further embodiments of the present disclosure, α-olefins copolymerizable with ethylene are one or more propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene, styrene, alpha-methylstyrene, and restricted cyclic olefins, such as cyclobutene, cyclopentene, dicyclopentadiene, norbornene, alkyl-substituted norbornene, alkenyl-substituted norbornene (e.g., 5-methylene-2-norbornene and 5-ethylidene-2-norbornene, bicyclo-(2,2,1)-hepta-2,5-diene).

[0123] In one embodiment of the present disclosure, the polyethylene composition comprises ethylene and one or more alphaolefins selected from the group consisting of 1-butene, 1-hexene, 1-octene and mixtures thereof.

[0124] In one embodiment of the present disclosure, the polyethylene composition comprises ethylene and one or more alphaolefins selected from the group including 1-hexene, 1-octene, and mixtures thereof.

[0125] In one embodiment of the present disclosure, the polyethylene composition comprises ethylene and 1-octene.

[0126] In one embodiment of the present disclosure, the polyethylene composition has one or more α-olefins in 0.1 to 7.5 mole percent, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has one or more α-olefins in 0.1 to 5.0 mole percent, or one or more α-olefins in 0.1 to 3.0 mole percent, or one or more α-olefins in 0.5 to 5.0 mole percent, or one or more α-olefins in 0.5 to 3 mole percent, or one or more α-olefins in 0.1 to 2.5 mole percent, or one or more α-olefins in 0.1 to 2.0 mole percent, or one or more α-olefins in 0.5 to 2.0 mole percent.

[0127] In embodiments of the present disclosure, the polyethylene composition contains 0.1 to 5.0 mol percent of 1-octene, or 0.1 to 3.0 mol percent of 1-octene, or 0.5 to 5.0 mol% of 1-octene, or 0.5 to 3 mol% of 1-octene, or 0.1 to 2.5 mol% of 1-octene, or 0.1 to 2.0 mol% of 1-octene, or 0.5 to 2.0 mol% of 1-octene.

[0128] In one embodiment of the present disclosure, a polyethylene composition comprising a first ethylene copolymer and a second ethylene copolymer (as defined above) has a ratio (SCB1 / SCB2) of at least 5.0 (i.e., SCB1 / SCB2 ≥ 5.0) between the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (i.e., SCB1) and the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer (i.e., SCB2). In a further embodiment of the present disclosure, the ratio of short-chain branches (SCB1) in the first ethylene copolymer to short-chain branches (SCB2) in the second ethylene copolymer is at least 7.5 or greater than 7.5. In yet further embodiments of the present disclosure, the ratio of short-chain branches (SCB1) in the first ethylene copolymer to short-chain branches (SCB2) in the second ethylene copolymer is at least 10.0 or greater than 10.0.

[0129] In one embodiment of the present disclosure, a polyethylene composition comprising a first ethylene copolymer and a second ethylene copolymer (as defined above) has a ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (i.e., SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (i.e., SCB2) of 5.0 to 100, or 5.0 to 75.0, or 5.0 to 50.0, or 7.5 to 75.0, or 7.5 to 50.0, or 10.0 to 50.0, or 10.0 to 75.0.

[0130] In one embodiment of the present disclosure, the polyethylene composition is characterized by the short-chain branching frequency at Mz (SCB-Mz), the short-chain branching frequency at Mw (SCB-Mw), and the short-chain branching frequency at Mn (SCB-Mn), where the short-chain branching frequency is the number of short-chain branches per 1000 carbon atoms in the polymer backbone at Mz, Mw, and Mn, respectively, as determined by GPC-FTIR analysis.

[0131] In one embodiment of the present disclosure, the polyethylene composition has a short-chain branching content that satisfies the following conditions: SCB-Mz > SCB-Mw > SCB-Mn.

[0132] In one embodiment of the present disclosure, the polyethylene composition has an SCB-Mz with more than 9.0 short-chain branches per 1000 carbon atoms in the polymer backbone.

[0133] In one embodiment of the present disclosure, the polyethylene composition has an SCB-Mw with 5.0 to 9.0 short-chain branches per 1000 carbon atoms in the polymer backbone.

[0134] In one embodiment of the present disclosure, the polyethylene composition has SCB-Mn having less than 5.0 short-chain branches per 1000 carbon atoms in the polymer backbone, or less than 4.0 short-chain branches per 1000 carbon atoms in the polymer backbone, or less than 3.0 short-chain branches per 1000 carbon atoms in the polymer backbone.

[0135] In embodiments of this disclosure, the polyethylene composition is 0.942 g / cm³. 3 Above, or 0.942 g / cm³ 3 More than 0.943 g / cm³ 3 Above, or 0.943 g / cm³ 3 It has an extremely high density.

[0136] In embodiments of this disclosure, the polyethylene composition is 0.942 to 0.965 g / cm³. 3 It has a density of 0.942 to 0.960 g / cm³, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition is 0.942 to 0.960 g / cm³. 3 , or 0.943~0.965 g / cm³ 3 , or 0.943~0.960 g / cm³ 3 , or 0.942~0.955 g / cm³ 3 , or 0.942~0.950 g / cm³ 3 , or 0.942~0.949 g / cm³ 3 , or 0.942~0.948 g / cm³ 3 , or 0.943~0.955 g / cm³ 3 , or 0.943~0.950 g / cm³ 3 , or 0.943~0.949 g / cm³ 3 , or 0.943~0.948 g / cm³ 3 It has a density of .

[0137] In one embodiment of this disclosure, the polyethylene composition is 0.941 g / cm³ 3 Super~0.949g / cm 3 It has a density of .

[0138] In one embodiment of this disclosure, the polyethylene composition is 0.941 g / cm³ 3 Super~0.948g / cm 3 It has a density of .

[0139] In one embodiment of the present disclosure, the polyethylene composition has a weight-average molecular weight M of 100,000 g / mol or less, or 80,000 g / mol or less, or 75,000 g / mol or less, or 70,000 g / mol or less, or less than 100,000 g / mol, or less than 80,000 g / mol, or less than 75,000 g / mol, or less than 70,000 g / mol. w It has.

[0140] In embodiments of this disclosure, the polyethylene composition has a weight-average molecular weight M of 30,000 to 150,000 g / mol. w Having, and including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a weight-average molecular weight M of 30,000 to 125,000 g / mol, or 35,000 to 100,000 g / mol, or 40,000 to 80,000 g / mol, or 45,000 to 80,000 g / mol, or 50,000 to 75,000 g / mol, or 55,000 to 70,000 g / mol. w It has.

[0141] In one embodiment of the present disclosure, the polyethylene composition has a number average molecular weight M of 60,000 g / mol or less, or 50,000 g / mol or less, or less than 50,000 g / mol, or 45,000 g / mol or less, or less than 45,000 g / mol, or 40,000 g / mol or less, or less than 40,000 g / mol, or 35,000 g / mol or less, or less than 35,000 g / mol, or 30,000 g / mol or less, or less than 30,000 g / mol, or 25,000 g / mol or less, or less than 25,000 g / mol. n It has.

[0142] In further embodiments of the present disclosure, the polyethylene composition has a number-average molecular weight M of 5,000 to 60,000 g / mol. nHaving, and including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a number average molecular weight M of 10,000 to 55,000 g / mol, or 10,000 to 50,000 g / mol, or 15,000 to 50,000 g / mol, or 15,000 to 45,000 g / mol, or 15,000 to 40,000 g / mol, or 15,000 to 35,000 g / mol, or 15,000 to 30,000 g / mol, or 15,000 to 25,000 g / mol, or 10,000 to 45,000 g / mol, or 10,000 to 40,000 g / mol, or 10,000 to 35,000 g / mol. n It has.

[0143] In one embodiment of the present disclosure, the polyethylene composition has a Z-average molecular weight M of 250,000 g / mol or less, or 225,000 g / mol or less, or 200,000 g / mol or less, or less than 250,000 g / mol, or less than 225,000 g / mol, or less than 200,000 g / mol. z It has.

[0144] In further embodiments of this disclosure, the polyethylene composition has a Z-average molecular weight M of 125,000 to 300,000 g / mol. z It has a range that includes any narrow range within this range and any value contained within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a Z-average molecular weight M of 125,000 to 275,000 g / mol, or 125,000 to 250,000 g / mol, or 125,000 to 225,000 g / mol, or 125,000 g / mol to 200,000 g / mol, or 125,000 to 190,000 g / mol, or 150,000 g / mol to 200,000 g / mol, or 175,000 g / mol to 200,000 g / mol, or 150,000 g / mol to 225,000 g / mol, or 110,000 g / mol to 175,000 g / mol, or 110,000 g / mol to 150,000 g / mol. z It has.

[0145] In one embodiment of the present disclosure, the polyethylene composition has a bimodal profile (i.e., a bimodal molecular weight distribution) in gel permeation chromatography (GPC) analysis.

[0146] In one embodiment of the present disclosure, the polyethylene copolymer composition has a bimodal profile in a gel permeation chromatograph generated according to the method of ASTM D6474-99.

[0147] In one embodiment of the present disclosure, the polyethylene composition has a unimodal profile (i.e., a unimodal molecular weight distribution) in gel permeation chromatography (GPC) analysis.

[0148] In one embodiment of the present disclosure, the polyethylene copolymer composition has a unimodal profile in a gel permeation chromatograph generated according to the method of ASTM D6474-99.

[0149] As used herein, the term "unimodal" is defined to mean that there is only one distinct significant peak or maximum in the GPC curve. In contrast, the use of the term "bimodal" is meant to convey that in addition to the first peak, there is a second peak or shoulder representing a higher or lower molecular weight component (i.e., the molecular weight distribution can be said to have two maxima in the molecular weight distribution curve). Alternatively, the term "bimodal" means that there are two maxima in the molecular weight distribution curve generated according to the method of ASTM D6474-99. The term "multimodal" means that there are two or more, typically more than two, maxima in the molecular weight distribution curve generated according to the method of ASTM D6474-99.

[0150] In an embodiment of the present disclosure, the polyethylene composition has a molecular weight distribution Mw of 6.0 or less, or less than 6.0, or 5.5 or less, or less than 5.5, or 5.0 or less, or less than 5.0, or 4.5 or less, or less than 4.5, or 4.0 or less, or less than 4.0, or 3.5 or less, or less than 3.5, or 3.0 or less, or less than 3.0. w / M n has. In a further embodiment of the present disclosure, the polyethylene composition has a molecular weight distribution M w / M n and includes any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the polyethylene composition has a molecular weight distribution M w / M n of 2.0 to 6.0, or 2.0 to 5.5, or 2.0 to 5.0, or 2.0 to 4.5, or 2.0 to 4.0, or 2.0 to 3.5, or 2.0 to 3.0, or less than 2.0 to 3.0.

[0151] In an embodiment of the present disclosure, the polyethylene composition has a melt index I2 of at least 4.0 g / 10 min (≥4.0 g / 10 min), or at least 4.5 g / 10 min (≥4.5 g / 10 min), or at least 5.0 g / 10 min (≥5.0 g / 10 min), or at least 5.5 g / 10 min (≥5.5 g / 10 min), or at least 6.0 g / 10 min (≥6.0 g / 10 min), or greater than 4.0 g / 10 min (>4.0 g / 10 min), or greater than 4.5 g / 10 min (>4.5 g / 10 min), or greater than 5.0 g / 10 min (>5.0 g / 10 min), or greater than 5.5 g / 10 min (>5.5 g / 10 min), or greater than 6.0 g / 10 min (>6.0 g / 10 min). In a further embodiment of the present disclosure, the polyethylene composition has a melt index I2 of 4.0 to 15.0 g / 10 min and includes any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the melt index I2 of the polyethylene composition may be 4.0 to 12.0 g / 10 min, or 4.5 to 12.0 g / 10 min, or 5.0 to 12.0 g / 10 min, or 4.0 to 10.0 g / 10 min, or 4.5 to 10.0 g / 10 min, or 5.0 to 10.0 g / 10 min, or 5.5 to 12.0 g / 10 min, or 6.0 to 12.0 g / 10 min, or 5.5 to 10.0 g / 10 min, or 6.0 to 10.0 g / 10 min, or 5.5 to 7.5 g / 10 min.

[0152] In embodiments of this disclosure, the polyethylene composition has a high load melt index I of at least 125 g / 10 min (≧125 g / 10 min), or greater than 125 g / 10 min (>125 g / 10 min), or at least 150 g / 10 min (≧150 g / 10 min), or greater than 150 g / 10 min (>150 g / 10 min), or at least 200 g / 10 min (≧200 g / 10 min), or greater than 200 g / 10 min (>200 g / 10 min), or at least 250 g / 10 min (≧250 g / 10 min), or greater than 250 g / 10 min (>250 g / 10 min). 21 In further embodiments of this disclosure, the polyethylene composition has a high-load melt index of 125 to 1,000 g / 10 min. 21 It has and includes any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the high-load melt index I of the polyethylene composition 21 The amount may be 125-750g / 10 minutes, or 125-500g / 10 minutes, or 150-400g / 10 minutes, or 125-400g / 10 minutes, or 125-350g / 10 minutes, or 125-300g / 10 minutes, or 125-250g / 10 minutes, or 150-250g / 10 minutes, or 150-225g / 10 minutes, or 200-350g / 10 minutes, or 225-350g / 10 minutes.

[0153] In embodiments of this disclosure, the polyethylene composition has a melt flow ratio I of 50 or less, or less than 50, or 45 or less, or less than 45. 21 / I2 is present. In further embodiments of this disclosure, the polyethylene composition has a melt flow ratio of 25 to 50, I 21 / I2 has any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a melt flow ratio I of 25-45, or 30-45, or 35-45, or 25-50, or 30-50, or 35-50, or 32-50, or 32-45, or greater than 25-50, or greater than 30-50, or greater than 32-50, or greater than 32-50 or less than 32-50. 21 It has / I2.

[0154] In embodiments of this disclosure, the polyethylene composition has a melt flow ratio I of 40 or less, or less than 40, or 35 or less, or less than 35, or 32 or less, or less than 32. 21 / I2 is present. In further embodiments of this disclosure, the polyethylene composition has a melt flow ratio of 15 to 40, I 21 Having / I2, and including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a melt flow ratio I of 15-35, or 15-32, or 18-40, or 18-35, or 18-32. 21 It has / I2.

[0155] In one embodiment of the present disclosure, the polyethylene composition has a reverse or partially reversed comonomer distribution profile as measured by GPC-FTIR. The distribution is described as “normal” if the comonomer incorporation decreases with molecular weight as measured by GPC-FTIR. The comonomer distribution is described as “flat” or “uniform” if the comonomer incorporation is nearly constant with respect to molecular weight as measured by GPC-FTIR. The terms “reverse comonomer distribution” and “partially reverse comonomer distribution” mean that in the GPC-FTIR data obtained for the copolymer, there is one or more high molecular weight components that have higher comonomer incorporation than one or more low molecular weight components. The term “reverse comonomer distribution” is used herein to mean that the comonomer content of various polymer fractions is not substantially uniform across the molecular weight range of the ethylene copolymer, and that its high molecular weight fraction has a proportionally higher comonomer content (i.e., if the comonomer incorporation increases with molecular weight, the distribution is described as “reverse” or “reversed”). Even if comonomer incorporation increases with increasing molecular weight and then decreases, the comonomer distribution is considered "inverted," but may be described as "partially inverted." A partially inverted comonomer distribution shows a peak or maximum value.

[0156] In one embodiment of the present disclosure, the polyethylene composition has an inverted comonomer distribution profile as measured using GPC-FTIR.

[0157] In one embodiment of the present disclosure, the polyethylene composition has a partially inverted comonomer distribution profile, as measured using GPC-FTIR.

[0158] In embodiments of this disclosure, the polyethylene composition contains about 30 to about 75% by weight, or about 30 to about 65% by weight, or about 30 to about 60% by weight, or about 35 to about 60% by weight of CDBI 50 It has.

[0159] In embodiments of the present disclosure, the upper limit of parts per million (ppm) of hafnium in the polyethylene composition may be about 3.0 ppm, or about 2.5 ppm, or about 2.4 ppm, or about 2.0 ppm, or about 1.5 ppm, or about 1.0 ppm, or about 0.75 ppm, or about 0.5 ppm. In embodiments of the present disclosure, the lower limit of parts per million (ppm) of hafnium in the polyethylene composition may be about 0.0015 ppm, or about 0.0050 ppm, or about 0.0075 ppm, or about 0.010 ppm, or about 0.015 ppm, or about 0.030 ppm, or about 0.050 ppm, or about 0.075 ppm, or about 0.100 ppm, or about 0.150 ppm, or about 0.175 ppm, or about 0.200 ppm.

[0160] In embodiments of this disclosure, the polyethylene composition contains 0.0015 to 2.4 ppm of hafnium, or 0.0050 to 2.4 ppm of hafnium, or 0.0075 to 2.4 ppm of hafnium, or 0.010 to 2.4 ppm of hafnium, or 0.015 to 2.4 ppm of hafnium, or 0.050 to 3.0 ppm of hafnium, or 0.050 to 2.4 ppm of hafnium, or 0.075 to 2.4 ppm of hafnium, or 0.075 to 2.0 ppm of hafnium, or 0.075 to 1.5 ppm of hafnium, or 0.075 to 1.0 ppm of hafnium, or 0.075 to 0 It contains 0.75 ppm of hafnium, or 0.100 to 2.0 ppm of hafnium, or 0.100 to 1.5 ppm of hafnium, or 0.100 to 1.0 ppm of hafnium, or 0.100 to 0.75 ppm of hafnium, or 0.20 to 2.0 ppm of hafnium, or 0.20 to 1.5 ppm of hafnium, or 0.20 to 1.0 ppm of hafnium, or 0.20 to 0.75 ppm of hafnium, or 0.35 to 2.0 ppm of hafnium, or 0.35 to 1.5 ppm of hafnium, or 0.35 to 1.0 ppm of hafnium, or 0.35 to 0.75 ppm of hafnium.

[0161] In embodiments of the present disclosure, the polyethylene composition contains at least 0.0015 ppm of hafnium, or at least 0.005 ppm of hafnium, or at least 0.0075 ppm of hafnium, or at least 0.015 ppm of hafnium, or at least 0.030 ppm of hafnium, or at least 0.050 ppm of hafnium, or at least 0.075 ppm of hafnium, or at least 0.100 ppm of hafnium, or at least 0.125 ppm of hafnium, or at least 0.150 ppm of hafnium, or at least 0.175 ppm of hafnium, or at least 0.200 ppm of hafnium, or at least 0.300 ppm of hafnium, or at least 0.350 ppm of hafnium.

[0162] In one embodiment of the present disclosure, the polyethylene composition includes long-chain branching characterized by the long-chain branching coefficient LCBF disclosed herein. In embodiments of the present disclosure, the upper limit of the LCBF of the polyethylene composition may be 0.3000 (dimensionless). In embodiments of the present disclosure, the lower limit of the LCBF of the polyethylene composition may be 0.0010, or 0.0020, or 0.0030 (dimensionless).

[0163] In embodiments of the present disclosure, the LCBF of the polyethylene composition is at least 0.0010, or at least 0.0020, or at least 0.0030, or at least 0.0040, or at least 0.0050, or at least 0.0060. In embodiments of the present disclosure, the LCBF of the polyethylene composition is greater than 0.0010, or greater than 0.0020, or greater than 0.0030, or greater than 0.0040, or greater than 0.0050, or greater than 0.0060.

[0164] In embodiments of this disclosure, the LCBF of the polyethylene composition is 0.0010 to 0.0090, or 0.0010 to 0.0080, or 0.0010 to 0.0070, or 0.0010 to 0.0060, or 0.0010 to 0.0050, or 0.0010 to 0.0040, or 0.0010 to 0.0030, or less than 0.0010 to 0.0060, or 0.0060 to 0.0095, or 0.0060 to 0.0090, or 0.0060 to 0.0085, or 0.0060 to 0.0080, or 0.0060 to 0.0075.

[0165] In embodiments of the present disclosure, the LCBF of the polyethylene composition is less than 0.0060, or less than 0.0050, or less than 0.0040, or less than 0.0030. In embodiments of the present disclosure, the LCBF of the polyethylene composition is 0.0060 or less, or 0.0050 or less, or 0.0040 or less, or 0.0030 or less. In embodiments of the present disclosure, the LCBF of the polyethylene composition is 0.0060 or less but at least 0.0010, or 0.0050 or less but at least 0.0010, or 0.0040 or less but at least 0.0010, or 0.0030 or less but at least 0.0010. In embodiments of this disclosure, the LCBF of the polyethylene composition is less than 0.0060 but at least 0.0010, or less than 0.0050 but at least 0.0010, or less than 0.0040 but at least 0.0010, or less than 0.0030 but at least 0.0010.

[0166] In embodiments of this disclosure, the polyethylene composition or plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR) of more than 500 hours, or more than 600 hours, or more than 700 hours, or more than 800 hours, or more than 900 hours, or more than 1000 hours in 100% IGEPAL CO-630 under condition A.

[0167] In embodiments of this disclosure, the polyethylene composition or plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR) of more than 500 hours, or more than 600 hours, or more than 700 hours, or more than 800 hours, or more than 900 hours, or more than 1000 hours in 100% IGEPAL CO-630 under condition B.

[0168] In embodiments of the present disclosure, the polyethylene composition or plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR) determined in 100% IGEPAL CO-630 for more than 500 hours, or more than 600 hours, or more than 700 hours, or more than 800 hours, or more than 900 hours, or more than 1000 hours, as determined in both conditions A and B.

[0169] In embodiments of the present disclosure, a polyethylene composition or a plaque made from a polyethylene composition has an environmental stress crack resistance (ESCR) determined under either Condition A or Condition B in 100% IGEPAL CO-630 that exceeds 500 hours, or exceeds 600 hours, or exceeds 700 hours, or exceeds 800 hours, or exceeds 900 hours, or exceeds 1000 hours.

[0170] In embodiments of the present disclosure, a polyethylene composition or a plaque made from a polyethylene composition has an environmental stress crack resistance (ESCR) under Condition B in 10% IGEPAL CO-630 that exceeds 500 hours, or exceeds 600 hours, or exceeds 700 hours, or exceeds 800 hours, or exceeds 900 hours, or exceeds 1000 hours.

[0171] In embodiments of the present disclosure, the polyethylene composition has a zero-shear viscosity (η0) at 190 °C of from about 750 Pa·s to about 5000 Pa·s, including any narrow range within this range and any value subsumed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a zero-shear viscosity η0 at 190 °C of from about 1000 Pa·s to about 4500 Pa·s, or from about 1000 Pa·s to about 4000 Pa·s, or from about 1000 Pa·s to about 3500 Pa·s, or from about 1000 Pa·s to about 3000 Pa·s, or from about 1500 Pa·s to about 3500 Pa·s, or from about 1500 Pa·s to about 3000 Pa·s, or from about 1750 Pa·s to about 2750 Pa·s, or from about 1750 Pa·s to about 2500 Pa·s, or from about 2000 Pa·s to about 2500 Pa·s.

[0172] In embodiments of the present disclosure, the polyethylene composition has a relative storage modulus G' / G'' at 0.05 rad / s that is less than 0.055, or less than 0.052, or 0.052 or less, or less than 0.050, or 0.050 or less.

[0173] In embodiments of the present disclosure, the polyethylene composition has a relative storage modulus G' / G'' at 0.5 rad / s that is less than 0.17, or less than 0.16, or 0.15 or less.

[0174] In embodiments of the present disclosure, the polyethylene composition has a melt strength of at least 0.75 cN, or at least 0.80 cN, or at least 0.85 cN, or at least 0.90 cN, or at least 0.95 cN, or at least 1.00 cN.

[0175] In embodiments of the present disclosure, the polyethylene composition has a melt strength elongation ratio greater than 1100, greater than 1200, greater than 1250, or at least 1100, or at least 1200, or at least 1250.

[0176] In embodiments of the present disclosure, a polyethylene composition or plaque made from a polyethylene composition has a 1% flexural secant modulus of at least 750 MPa or greater than 750 MPa, or at least 800 MPa or greater than 800 MPa, or at least 850 MPa or greater than 850 MPa, or at least 900 MPa or greater than 900 MPa, or at least 950 MPa or greater than 950 MPa. In further embodiments of the present disclosure, a polyethylene composition or plaque made from a polyethylene composition has a 1% flexural secant modulus of 750 to 1200 MPa, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, a polyethylene composition or plaque made from a polyethylene composition has a 1% flexural secant modulus of 800 to 1100 MPa, or 850 to 1050 MPa, or 850 to 1000 MPa, or 900 to 1100 MPa, or 900 to 1050 MPa, or 900 to 1000 MPa.

[0177] In embodiments of the present disclosure, a polyethylene composition or plaque made from a polyethylene composition has a tensile secant modulus at 1% of at least 750 MPa, or greater than 750 MPa, or at least 800 MPa, or greater than 800 MPa, or at least 850 MPa, or greater than 850 MPa, or at least 900 MPa, or greater than 900 MPa, or at least 950 MPa. In further embodiments of the present disclosure, a polyethylene composition or plaque made from a polyethylene composition has a tensile secant modulus at 1% of 750 to 1200 MPa, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, a polyethylene composition or plaque made from a polyethylene composition has a tensile secant modulus at 1% of 800 to 1100 MPa, or 850 to 1050 MPa, or 850 to 1000 MPa, or 900 to 1100 MPa, or 900 to 1050 MPa, or 900 to 1000 MPa.

[0178] In embodiments of the present disclosure, a polyethylene composition or a plaque made from a polyethylene composition has an IZOD impact strength of ≥7.0 ft-pounds / inch, or >7.0 ft-pounds / inch, or ≥8.0 ft-pounds / inch, or >8.0 ft-pounds / inch, or ≥9.0 ft-pounds / inch, or >9.0 ft-pounds / inch, or ≥10.0 ft-pounds / inch, or >10.0 ft-pounds / inch. In further embodiments of the present disclosure, a polyethylene composition or a plaque made from a polyethylene composition has an IZOD impact strength of 7.0 to 15.0 ft-pounds / inch, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, a polyethylene composition or a plaque made from a polyethylene composition has an IZOD impact strength of 8.0 to 15.0 ft-pounds / inch, or 9.0 to 15.0 ft-pounds / inch, or 10.0 to 15.0 ft-pounds / inch.

[0179] In embodiments of this disclosure, the polyethylene composition or plaque made from the polyethylene composition is ≥140 ft-pounds / inch 2 , or ≥160 ft-pounds / inch 2 , or ≥180 ft-pounds / inch 2 , or ≥200 ft-pounds / inch 2 It has a tensile impact strength of 140 to 450 ft-pounds / inch. In embodiments of this disclosure, the polyethylene composition or plaque made from the polyethylene composition has a tensile impact strength of 140 to 450 ft-pounds / inch. 2 , or 160-400 ft-pounds / inch 2 , or 180-250 ft-pounds / inch 2 , or 160-240 ft-pounds / inch 2 , or 160-375 ft-pounds / inch 2 It has a tensile impact strength of [value].

[0180] Additives may be optionally added to the polyethylene composition. Additives may be added to the polyethylene composition during the extrusion or compounding process, but other suitable known methods will be apparent to those skilled in the art. Additives may be added as is, or as part of a separate polymer component (i.e., not the first or second ethylene polymer described above) added during the extrusion or compounding process. Suitable additives known in the art include, but are not limited to, antioxidants, phosphates and phosphonites, nitrones, antacids, UV stabilizers, UV absorbers, metal deactivators, dyes, fillers and reinforcing agents, nanoscale organic or inorganic materials, antistatic agents, lubricants such as calcium stearate, anti-slip additives such as erucamide, and nucleating agents (including nucleating agents, pigments, or other chemicals that may impart a nucleating effect to the polyethylene composition). Optionally added additives are typically added in amounts up to 20% by weight (wt%).

[0181] One or more nucleating agents can be introduced into a polyethylene composition by kneading a mixture of the polymer (usually in the form of powder or pellets) and the nucleating agent. The nucleating agent can be used alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatic agents, UV stabilizers, and fillers. It must be a material that is wetted or absorbed by the polymer, insoluble in the polymer, has a melting point higher than the polymer's melting point, and can be uniformly dispersed in the polymer molten material in the finest possible form (1-10 μm). Compounds known to have nucleating ability in polyolefins include salts of aliphatic monobasic or dibasic acids or arylalkyl acids (such as sodium succinate or aluminum phenylacetate); and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids (such as sodium β-naphthoate). Another compound known to have nucleating ability is sodium benzoate. The nucleating effect can be monitored microscopically by observing the degree of reduction in the size of spherulites formed by the aggregation of crystallites.

[0182] Examples of commercially available nucleating agents that can be added to polyethylene compositions include dibenzylidene sorbital ester (for example, the product sold by Milliken Chemical under the trademark MILLAD® 3988, and the product sold by Ciba Specialty Chemicals under the trademark IRGACLEAR®). Further examples of nucleating agents that can be added to polyethylene compositions include the cyclic organic structure (and its salts, e.g., disodium bicyclo[2.2.1]heptenedicarboxylate) disclosed in U.S. Patent No. 5,981,636; saturated versions of the structure disclosed in U.S. Patent No. 5,981,636 (disclosed in U.S. Patent No. 6,465,551; from Zhao et al. to Milliken); salts of certain cyclic dicarboxylic acids having a hexahydrophthalic acid structure (or "HHPA" structure) disclosed in U.S. Patent No. 6,599,971 (from Dotson et al. to Milliken); and cyclic dicarboxylic acid salts and salts thereof, such as phosphate esters disclosed in U.S. Patent No. 5,342,868 and sold by Asahi Denka Kogyo under the trade names NA-11 and NA-21, and divalent metal salts or metalloid salts (especially calcium salts) of the HHPA structure disclosed in U.S. Patent No. 6,599,971. For clarity, an HHPA structure generally comprises a ring structure having six carbon atoms in the ring and two carboxylic acid groups that are substituents on atoms adjacent to the ring structure. The other four carbon atoms in the ring may be substituted, as disclosed in U.S. Patent No. 6,599,971. One example is calcium 1,2-cyclohexanedicarboxylate (CAS Registry No. 491589-22-1). Further examples of nucleating agents that can be added to polyethylene compositions are disclosed in International Publication Nos. 2015 / 042561, 2015 / 042563, 2015 / 042562, and 2011 / 050042.

[0183] Many of the nucleating agents mentioned above can be difficult to mix with the polyethylene composition on which they form nucleation. To mitigate this problem, it is known that dispersing agents such as zinc stearate are used.

[0184] In one embodiment of the present disclosure, the nucleating agent is well dispersed in the polyethylene composition.

[0185] In one embodiment of the present disclosure, since the amount of nucleating agent used is relatively small (5 to 3,000 ppm by weight, based on the weight of the polyethylene composition), it will be understood by those skilled in the art that some care must be taken to ensure that the nucleating agent is well dispersed. In one embodiment of the present disclosure, the nucleating agent is added to the polyethylene composition in a finely divided form (less than 50 microns, particularly less than 10 microns) to facilitate mixing. This type of “physical blend” (i.e., a mixture of the nucleating agent and resin in solid form) is generally preferred over using a “masterbatch” of the nucleating agent (wherein the term “masterbatch” refers to an embodiment in which the additive (in this case, the nucleating agent) is first melt-mixed with a small amount of polyethylene composition resin, and then the “masterbatch” is melt-mixed with the remaining bulk of the polyethylene composition resin).

[0186] In one embodiment of the present disclosure, additives such as nucleating agents may be added to the polyethylene composition in a “masterbatch” manner, where the term “masterbatch” refers to an embodiment in which the additive (e.g., nucleating agent) is first melt-mixed with a small amount of polyethylene composition, and then the “masterbatch” is melt-mixed with the remaining bulk of the polyethylene composition.

[0187] In one embodiment of the present disclosure, the polymer composition further comprises a nucleating agent or a mixture of nucleating agents.

[0188] In one embodiment of the present disclosure, the polyethylene composition is used to form molded articles. For example, molded articles formed by rotational molding, continuous compression molding, or injection molding may be considered. Such molded articles include, for example, tanks formed by rotational molding, and bottle caps, screw caps, and closures formed by compression molding or injection molding. However, those skilled in the art will understand that the above-described composition can also be used in other applications, but are not limited to, films, injection blow molding, blow molding, and sheet extrusion applications.

[0189] In one embodiment, the polyethylene composition disclosed herein can be converted into a molded article.

[0190] In one embodiment, the polyethylene compositions disclosed herein can be used to manufacture articles by a rotational molding process.

[0191] In one embodiment, the polyethylene composition disclosed herein can be converted into a rotationally molded article.

[0192] In some embodiments, as an alternative to rotational molding, the polyethylene compositions of the present disclosure can be used to manufacture articles by extrusion, compression, or injection molding processes.

[0193] <Rotomolded Articles> Typically, polyethylene compositions can be manufactured in the form of powder or pellets for use in a rotational molding process. The rotational molding process may further include process steps for manufacturing the polyethylene composition. Powder is preferably used for rotational molding, and its particle size may be 35 US mesh or less. Grinding may be performed at cryogenic temperatures if necessary. The polymer powder is then placed in a hollow mold and heated inside the mold while the mold is rotated. The mold is usually rotated in two axes, that is, simultaneously around two vertical axes. The mold is typically heated from the outside (generally using a forced air circulation oven). Generally, the rotational molding process steps include tumbling, heating, and melting the polymer powder, followed by agglomeration, fusion, or sintering, and cooling to remove the molded product.

[0194] The polyethylene compositions of this disclosure can be processed in a commercially available rotational molding machine in certain embodiments of this disclosure. The time and temperature used depend on factors including the thickness of the part being rotationally molded, and appropriate processing conditions can be easily determined by those skilled in the art. To give some non-limiting examples, the oven temperature range during the heating process can be 400°F to 800°F, or about 500°F to about 700°F, or about 575°F to about 650°F.

[0195] After the heating process, the mold is cooled. The parts need to be sufficiently cooled so that they can be easily removed from the mold and maintain their shape. The mold may be removed from the oven while rotating it. First, cool air is blown onto the mold. The air may be at ambient temperature. After a controlled time, when the air has begun to cool the mold, a water spray may be used. The mold is rapidly cooled by the water. The water used may be cold tap water, for example, at a temperature of about 4°C (40°F) to about 16°C (60°F). After the water cooling process, another air cooling process may be performed. This may be a short process to dry the equipment by removing heat as the water evaporates.

[0196] The heating and cooling cycle times vary depending on the equipment used and the article being molded. Specific factors include the thickness of the part in the mold material. As a non-limiting example, the conditions for a 1 / 8-inch thick part in a steel mold may be as follows: the mold is heated in an oven with air at approximately 316°C (600°F) for approximately 15 minutes; the part is then cooled by forced air cooling at ambient temperature for approximately 8 minutes, followed by cooling by spraying with tap water at approximately 10°C (50°F) for approximately 5 minutes; optionally, the part may be cooled further by forced air cooling at ambient temperature for an additional 2 minutes.

[0197] During the heating and cooling processes, the mold containing the molded product is preferably rotated continuously. Typically, this is done along two vertical axes. The rotational speed of the mold around each axis is limited by the capabilities of the machine and the shape of the article being molded. A typical non-limiting range of operation that can be used in this disclosure is a rotational ratio of the major axis to the minor axis of about 1:8 to 10:1, or about 1:2 to 8:1.

[0198] Non-limiting examples of molded products that can be manufactured using rotational molding processes include custom tanks, water tanks, carts, transport cases and containers, coolers, sports and recreational equipment (boats, kayaks, etc.), toys, and play equipment.

[0199] The desirable physical properties of rotationally molded parts vary depending on the intended application. Non-limiting examples of desirable properties include flexural modulus (1% and 2% secant modulus), environmental stress crack resistance (ESCR), Shore hardness, thermal deflection temperature (HDT), VICAT softening point, IZOD impact strength, ARM impact resistance, and color (whiteness and / or yellowness index).

[0200] In one embodiment of the present disclosure, a rotationally molded article having an internal volume of less than approximately 100 liters is prepared using a polyethylene composition having a melt index (I2) greater than approximately 6 g / 10 min.

[0201] In one embodiment of the present disclosure, a rotationally molded article having a volume of less than 50 liters is prepared using a polyethylene composition having a melt index (I2) of about 6 to about 12 g / 10 min.

[0202] In one embodiment of the present disclosure, a process for producing a rotationally molded product comprises the following steps: (i) filling a mold with a polyethylene composition; (ii) heating the mold in an oven to a temperature exceeding 280°C; (iii) rotating the mold around at least two axes; (iv) cooling the mold while it is rotating; and (v) opening the mold and removing the rotationally molded product.

[0203] <Additives and Auxiliaries - Rotational Molded Products> The polyethylene compositions described and the rotationally molded articles produced may optionally contain additives and auxiliaries depending on their intended use. Additives may be added to the polyethylene compositions during the extrusion or compounding process, but other suitable known methods will be apparent to those skilled in the art. Additives may be added as is or as part of a separate polymer component added during the extrusion or compounding process. Non-limiting examples of additives and auxiliaries include anti-blocking agents, antioxidants, heat stabilizers, slip agents, processing aids, antistatic additives, colorants, dyes, fillers, light stabilizers, heat stabilizers, light absorbers, lubricants, pigments, plasticizers, nucleating agents, and combinations thereof. Non-limiting examples of suitable primary antioxidants include IRGANOX® 1010 [CAS Registry No. 6683-19-8] and IRGANOX 1076 [CAS Registry No. 2082-79-3]; both are available from BASF Corporation (Florham Park, New Jersey, USA). Some non-exclusive examples of suitable secondary antioxidants include IRGAFOS® 168 [CAS Reg. No. 31570-04-4], available from BASF Corporation (Florham Park, New Jersey, USA); Weston 705 [CAS Reg. No. 939402-02-5], available from Addivant (Danbury, Connecticut, USA); and DOVERPHOS® IGP-11 [CAS Reg. No. 1227937-46-3], available from Dover Chemical Corporation (Dover, Ohio, USA). Optional additives are typically added in amounts up to 20% by weight (wt%).

[0204] One or more nucleating agents can be introduced into a polyethylene composition by kneading a mixture of the polymer (usually in the form of powder or pellets) and the nucleating agent. The nucleating agent can be used alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatic agents, UV stabilizers, and fillers. It must be a material that is wetted or absorbed by the polymer, insoluble in the polymer, has a melting point higher than the polymer's melting point, and can be uniformly dispersed in the polymer molten material in the finest possible form (1-10 μm). Compounds known to have nucleating ability in polyolefins include salts of aliphatic monobasic or dibasic acids or arylalkyl acids (such as sodium succinate or aluminum phenylacetate); and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids (such as sodium β-naphthoate). Another compound known to have nucleating ability is sodium benzoate. The nucleating effect can be monitored microscopically by observing the degree of reduction in the size of spherulites formed by the aggregation of crystallites.

[0205] In embodiments of the present disclosure, the polyethylene compositions described and the rotationally molded articles produced may contain additives selected from the group including antioxidants, phosphates and phosphonites, nitrones, antacids, ultraviolet stabilizers, ultraviolet absorbers, metal deactivators, dyes, fillers and reinforcing agents, nanoscale organic or inorganic materials, antistatic agents, mold release agents such as zinc stearate, and nucleating agents (including nucleating agents, pigments, or other chemicals that may impart a nucleating effect to the polyethylene composition).

[0206] In embodiments of this disclosure, additives that may be added are added in an amount of up to 20% by weight (wt%).

[0207] Additives can be added to the polyethylene composition during the extrusion or compounding process, but other suitable known methods will be apparent to those skilled in the art. Additives can be added as is, or as part of a separate polymer component added during the extrusion or compounding process.

[0208] A more detailed list of additives that can be added to the polyethylene compositions of this disclosure and used in rotationally molded articles is given below:

[0209] <Phosphite (e.g., aryl monophosphite)> As used herein, the term aryl monophosphite means a phosphite stabilizer that (1) contains only one phosphorus atom per molecule; and (2) contains at least one aryl oxide (also called phenoxide) radical bonded to phosphorus.

[0210] In one embodiment of the present disclosure, the aryl monophosphite comprises three aryl oxide radicals, for example, trisphenyl phosphite is the simplest member of this preferred group of aryl monophosphites.

[0211] In another embodiment of the present disclosure, the aryl monophosphine has at least one aryl oxide group with C1-C 10 This includes alkyl substituents. These substituents may be linear (in the case of nonyl substituents) or branched (in the case of isopropyl substituents or tert-butyl substituents, etc.).

[0212] Non-limiting examples of aryl monophosphites that can be used in embodiments of the present disclosure include triphenyl phosphite; diphenylalkyl phosphite; phenyl dialkyl phosphite; tris(nonylphenyl) phosphite [WESTON 399, available from GE Specialty Chemicals]; tris(2,4-di-tert-butylphenyl) phosphite [IRGAFOS 168, available from Ciba Specialty Chemicals Corp.]; and bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite [IRGAFOS 38, available from Ciba Specialty Chemicals Corp.]; and 2,2',2''-nitrilo[triethyltris(3,3'5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl) phosphite [IRGAFOS 12, available from Ciba Specialty Chemicals Corp.].

[0213] In embodiments of this disclosure, the amount of aryl monophosphine added to the polyethylene composition is 200 to 2,000 ppm (based on the weight of the polymer), or 300 to 1,500 ppm, or 400 to 1,000 ppm.

[0214] <Phosphites, phosphonates (e.g., diphosphites, diphosphonates)> As used herein, the term diphosphite refers to a phosphite stabilizer containing at least two phosphorus atoms per phosphite molecule (similarly, the term diphosphonite refers to a phosphonite stabilizer containing at least two phosphorus atoms per phosphonite molecule).

[0215] Non-limiting examples of diphosphites and diphosphonites that can be used in embodiments of this disclosure include distearyl pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite [ULTRANOX® 626, available from GE Specialty Chemicals]; bis(2,6-di-tert-butyl-4-methylpenyl) pentaerythritol diphosphite; bisdecyloxy pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite [IRGAFOS Examples include P-EPQ, available from Ciba; and bis(2,4-dicumylphenyl)pentaerythritol diphosphite [DOVERPHOS S9228-T or DOVERPHOS S9228-CT]; and PEP-Q® (CAS number 119345-01-06), an example of a commercially available diphosphonite.

[0216] In embodiments of this disclosure, the diphosphite and / or diphosphonite added to the polyethylene composition is added in an amount of 200 ppm to 2,000 ppm (based on the weight of the polymer), or 300 to 1,500 ppm, or 400 to 1,000 ppm.

[0217] In one embodiment of the present disclosure, the use of a diphosphite is preferred over the use of a diphosphonite.

[0218] In one embodiment of the present disclosure, the most preferred diphosphites are those available under the trademarks Doverphos S9228-CT and ULTRANOX 626.

[0219] <Hindered phenol-based antioxidants> The antioxidant may be any of the molecules conventionally used as hindered phenol antioxidants or primary antioxidants for stabilizing polyolefins. Suitable examples include 2,6-di-tert-butyl-4-methylphenol; 2-tert-butyl-4,6-dimethylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,6-di-tert-butyl-4-n-butylphenol; 2,6-di-tert-butyl-4-isobutylphenol; 2,6-dicyclopentyl-4-methylphenol; 2-(alpha-methylcyclohexyl)-4,6-dimethylphenol; 2,6-di-octadecyl-4-methylphenol; 2,4,6-tricyclohexylphenol; and 2,6-di-tert-butyl-4-methoxymethylphenol.

[0220] Two (non-limiting) examples of suitable hindered phenol antioxidants that can be used in embodiments of the present disclosure are sold by BASF Corporation under the trademark IRGANOX 1010 (CAS Registry No. 6683-19-8) and the trademark IRGANOX 1076 (CAS Registry No. 2082-79-3).

[0221] In one embodiment of the present disclosure, the amount of hindered phenol antioxidant added to the polyethylene composition is 100 to 2,000 ppm, or 400 to 1,000 ppm (based on the weight of the polymer).

[0222] <Long-term tranquilizer> Plastic components intended for long-term use may, in embodiments of this disclosure, contain at least one hindered amine light stabilizer (HALS). HALS are well known to those skilled in the art.

[0223] When using HALS, in one embodiment of this disclosure, HALS may be a commercially available material and may be used in conventional methods and conventional amounts.

[0224] Commercially available HALS that can be used in embodiments of this disclosure include those sold by Ciba Specialty Chemicals Corporation under the trademarks CHIMASSORB® 119; CHIMASSORB 944; CHIMASSORB 2020; TINUVIN® 622 and TINUVIN 770, and those sold by Cytec Industries under the trademarks CYASORB® UV 3346, CYASORB UV 3529, CYASORB UV 4801 and CYASORB UV 4802. In some embodiments of this disclosure, TINUVIN 622 is preferred. In other embodiments of this disclosure, the use of mixtures of two or more HALS is also envisioned.

[0225] In embodiments of this disclosure, preferred HALS include bis(2,2,6,6-tetramethylpiperidyl)-sebacate; bis-5(1,2,2,6,6-pentamethylpiperidyl)-sebacate; n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate bis(1,2,2,6,6-pentamethylpiperidyl) ester; condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxy-piperidine and succinic acid; N,N'-(2,2,6,6- Examples of HALS selected from tetramethylpiperidyl)-hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-s-triazine; tris-(2,2,6,6-tetramethylpiperidyl)-nitrilotriacetate, tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarbonate; and 1,1'(1,2-ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinone).

[0226] <Hydroxylamine> Hydroxylamines and their derivatives (including amine oxides) are known to be used as additives in polyethylene compositions used to prepare rotationally molded parts (for example, as disclosed in U.S. Patent No. 6,444,733), and in embodiments of this disclosure, the hydroxylamines and derivatives disclosed in this patent may also be suitable for use.

[0227] In one embodiment of this disclosure, a hydroxylamine useful for inclusion in a polyethylene composition can be selected from N,N-dialkylhydroxylamines, a commercially available example of which is N,N-di(alkyl)hydroxylamine sold as IRGASTAB FS042 (manufactured by BASF), which has been reported to be prepared by the direct oxidation of N,N-di(hydrogenated) fatamines.

[0228] In embodiments of the present disclosure, the amount of hydroxylamine added to the polyethylene composition is 100 to 2,000 ppm, or 400 to 1,000 ppm (based on the weight of the polymer). In embodiments of the present disclosure, the amount of hydroxylamine added to the polyethylene composition is at least about 400 ppm, or at least about 500 ppm, or at least about 600 ppm, or at least about 700 ppm, or at least about 750 ppm, or at least about 800 ppm, or 400 to 1,000 ppm (based on the weight of the polymer), based on the weight of the polymer.

[0229] In one embodiment of the present disclosure, the polyethylene composition contains an additive package comprising a hindered monophosphite, a diphosphite, a hindered amine light stabilizer, and at least one additional additive selected from the group consisting of hindered phenol and hydroxylamine.

[0230] Further non-limiting details of this disclosure are provided in the following embodiments. The embodiments are presented for illustrative purposes of selected embodiments of this disclosure, and it is understood that the examples presented are not intended to limit the scope of the presented claims. [Examples]

[0231] Prior to testing, each test specimen was conditioned at 23±2°C and 50±10% relative humidity for at least 24 hours, and unless otherwise specified, subsequent testing was carried out at 23±2°C and 50±10% relative humidity. In this specification, the term "ASTM conditions" refers to a laboratory maintained at 23±2°C and 50±10% relative humidity, where the test specimens were conditioned for at least 24 hours prior to testing. ASTM refers to the American Society for Testing and Materials.

[0232] <density> The density of the polyethylene composition was determined using ASTM D792-13 (November 1, 2013).

[0233] <Melt Index> The melt index of the polyethylene composition was determined using ASTM D1238 (August 1, 2013). Melt index: I2, I6, I 10 , and I 21 These were measured at 190°C using weights of 2.16 kg, 6.48 kg, 10 kg, and 21.6 kg, respectively. In this specification, the term "stress index" or its acronym "S.Ex." is defined by the following relationship: S.Ex.=log(I6 / I2) / log(6480 / 2160) (In the formula, I6 and I2 are the melt flow rates measured at 190°C using loads of 6.48 kg and 2.16 kg, respectively). In this disclosure, the melt index is expressed in units of g / 10 min, g / 10 min, dg / min, or dg / min, and these units are equivalent.

[0234] <Gel Permeation Chromatography (GPC)> Molecular weight M of polyethylene composition n M w M z , and polydispersity (M w / M nThe ) was determined using ASTM D6474-12 (December 15, 2012). Polymer sample solutions (1-2 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150°C for 4 hours. To stabilize the polymer against oxidative degradation, an antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture. The BHT concentration was 250 ppm. The sample solutions were chromatographed at 140°C at a flow rate of 1.0 mL / min using TCB as the mobile phase in a PL220 high-temperature chromatography unit equipped with four SHODEX® columns (HT803, HT804, HT805, and HT806), with differential refractive index (DRI) as the concentration detector. To protect the GPC columns from oxidative degradation, BHT was added to the mobile phase at a concentration of 250 ppm. The sample injection volume was 200 μL. GPC raw data was processed with CIRRUS® GPC software. The GPC column was calibrated with a narrow-distribution polystyrene standard. Polystyrene molecular weight was converted to polyethylene molecular weight using the Mark-Houwink formula, as described in ASTM D6474-12 (December 15, 2012).

[0235] <Triple detection size exclusion chromatography (3D-SEC)> Polyethylene composition sample (polymer) solutions (1-3 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150°C for 4 hours. To stabilize the polymer against oxidative degradation, an antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture. The BHT concentration was 250 ppm. The sample solutions were chromatographed at 140°C using a PL 220 high-temperature chromatography unit equipped with a differential refractive index (DRI) detector, dual-angle light scattering detectors (15° and 90°), and a differential viscometer. The SEC columns used were either four SHODEX columns (HT803, HT804, HT805, and HT806) or four PL Mixed ALS or BLS columns. TCB was used as the mobile phase at a flow rate of 1.0 mL / min, and BHT was added to the mobile phase at a concentration of 250 ppm to protect the SEC column from oxidative degradation. The sample injection volume was 200 μL. Raw SEC data was processed with CIRRUS GPC software to calculate the absolute molar mass and intrinsic viscosity ([η]). The term "absolute" molar mass was used to distinguish between the absolute molar mass determined by 3D-SEC and the molar mass determined by conventional SEC. Viscosity-average molar mass (M) determined by 3D-SEC v The long-chain branching coefficient (LCBF) was determined using the following formula.

[0236] <gpc-ftir> Polyethylene composition (polymer) solutions (2-4 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150°C for 4 hours. An antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. The sample solutions were chromatographed using TCB as the mobile phase at a flow rate of 1.0 mL / min and 140°C in a Waters GPC 150C chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805, HT806). As a detection system, an FTIR spectrometer and a heated FTIR flow-through cell were connected to the chromatography unit via a heated transfer line. BHT was added to the mobile phase at a concentration of 250 ppm to protect the SEC columns from oxidative degradation. The sample injection volume was 300 μL. Raw FTIR spectra were processed with OPUS FTIR software, and polymer concentrations and methyl content were calculated in real time using the chemometric software (PLS technique) associated with OPUS. Polymer concentrations and methyl content were then obtained and baseline-corrected using CIRRUS GPC software. SEC columns were calibrated with narrow-distribution polystyrene standards. Polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink formula, as described in ASTM standard test method D6474. Comonomer content was calculated based on the polymer concentrations and methyl content predicted by the PLS technique, as described in Paul J. DesLauriers, Polymer 43, pp. 159–170 (2002); incorporated herein by reference.

[0237] The GPC-FTIR method measures the total methyl content, including methyl-terminated groups located at the ends of each polymer chain. Therefore, raw GPC-FTIR data needs to be corrected by subtracting the contribution from the methyl-terminated groups. To clarify, raw GPC-FTIR data overestimates the amount of short-chain branching (SCBs), and this overestimation increases as the molecular weight (M) decreases. In this disclosure, raw GPC-FTIR data were corrected using the 2-methyl correction. Given a molecular weight (M), the following formula applies: N E =28000 / M used for methyl terminal group (N E Calculate the number of N E (M-dependent) was subtracted from the raw GPC-FTIR data to create SCB / 1000C (2-methyl corrected) GPC-FTIR data.

[0238] <Unsaturated content> The amount of unsaturated groups, i.e., double bonds, in polyethylene compositions was determined according to ASTM D3124-98 (vinylidene unsaturated, published March 2011) and ASTM D6248-98 (vinyl and trans unsaturated, published July 2012). Polymer samples were subjected to the following procedures: a) carbon disulfide extraction to remove any additives that may interfere with the analysis; b) pressing the sample (pellet, film, or granules) to form a plaque of uniform thickness (0.5 mm); and c) analysis of the plaque by FTIR.

[0239] <Comonomer content: Fourier transform infrared (FTIR) spectroscopy> The amount of comonomers in the polyethylene composition was determined by FTIR and reported as the short-chain branch (SCB) content with dimensions of CH3# / 1000C (number of methyl branches per 1000 carbon atoms). This test was completed using compression-molded polymer plaques and a Thermo-Nicolet 750 Magna-IR spectrophotometer according to ASTM D6645-01 (2001). The polymer plaques were prepared using a compression molding apparatus (Wabash-Genesis series press) according to ASTM D4703-16 (April 2016).

[0240] <Composition Distribution Branching Index (CDBI) by CTREF> The "Composition Distribution Branching Index" or "CDBI" of the disclosed examples and comparative examples was determined using a Crystallizing-TREF unit ("CTREF" unit) commercially available from Polymer Char (Valencia, Spain). The acronym "TREF" refers to Temperature Rising Elution Fractionation. A sample (80 - 100 mg) of the polyethylene composition was placed in the reactor of the Polymer Char Crystallizing-TREF unit, and the reactor was filled with 35 ml of 1,2,4-trichlorobenzene (TCB), heated to 150°C, and held at this temperature for 2 hours to dissolve the sample. Next, an aliquot (1.5 mL) of the TCB solution was loaded onto a Polymer Char TREF column packed with stainless steel beads, and the column was equilibrated at 110°C for 45 minutes. Then, the polyethylene composition was crystallized from the TCB solution within the TREF column by slowly cooling the TREF column from 110°C to 30°C at a cooling rate of 0.09°C per minute. Thereafter, the TREF column was equilibrated at 30°C for 30 minutes. Next, while slowly raising the temperature of the TREF column from 30°C to 120°C at a heating rate of 0.25°C per minute, a pure TCB solvent was passed through the column at a flow rate of 0.75 mL / min to elute the crystallized polyethylene composition from the TREF column. Using Polymer Char software, a TREF distribution curve was created when the polyethylene composition eluted from the TREF column. That is, the TREF distribution curve is a plot of the amount (or intensity) of the polymer material eluting from the column as a function of the TREF elution temperature. For each polyethylene composition analyzed, CDBI 50 was calculated. "CDBI 50 The TREF elution temperature is defined as the percentage of polymers whose composition is within 50% of the median comonomer composition (25% on each side of the median comonomer composition). This is calculated from the TREF composition distribution curve and the normalized cumulative integral of the TREF composition distribution curve. Those skilled in the art will understand that a calibration curve is necessary to convert the TREF elution temperature into comonomer content, i.e., the amount of comonomer in the polyethylene composition fraction that elutes at a specific temperature. The preparation of such a calibration curve is described in the prior art, for example, Wild et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20(3), pp. 441-455.

[0241] <Hexane extract> Hexane extracts were determined in accordance with Federal Regulation 21 CFR §177.1520 Para(c) 3.1 and 3.2. The amount of hexane-extractable substances in the sample was determined by gravimetric analysis.

[0242] <Neutron activation analysis (NAA)> Catalyst residues in polyethylene compositions were determined using neutron activation analysis (NAA) as follows: Polymer samples were packed into radiation vials (made of ultra-high-purity polyethylene, internal capacity 7 mL), and the sample weight was recorded. Using a pneumatic transfer system, the samples were placed inside a SLOWPOKE® reactor (Atomic Energy of Canada Limited, Ottawa, Ontario, Canada) and irradiated for 30-600 seconds for elements with short half-lives (e.g., Ti, V, Al, Mg, and Cl) or 3-5 hours for elements with long half-lives (e.g., Zr, Hf, Cr, Fe, and Ni). The average thermal neutron flux inside the reactor was 5 × 10⁻¹⁶. 11 / cm 2 The irradiation time was / s. After irradiation, the sample was removed from the reactor and aged to decay its radioactivity; elements with short half-lives were aged for 300 seconds, and elements with long half-lives were aged for several days. After aging, the gamma-ray spectrum of the sample was recorded using a germanium semiconductor gamma-ray detector (Ortec model GEM55185, Advanced Measurement Technology Inc., Oak Ridge, Tennessee, USA) and a multi-channel analyzer (Ortec model DSPEC Pro). The amount of each element in the sample was calculated from the gamma-ray spectrum and recorded as parts per million (ppm) relative to the total weight of the polymer sample. The NAA system was calibrated using Specpure standards (1,000 ppm solution of the desired element (purity over 99%)). 1 mL of the solution (of the target element) was pipetteed onto a 15 mm × 800 mm rectangular paper filter and air-dried. The filter paper was then placed in a 1.4 mL polyethylene irradiation vial and analyzed using the NAA system. Use the standard to determine the sensitivity (counts / μg) of the NAA procedure.

[0243] <Dynamic mechanical analysis (DMA)> Vibrational shear measurements were performed at small strain amplitudes, and linear viscoelastic functions were obtained in a frequency range of 0.02 to 126 rad / s at 190°C in an N2 atmosphere, with a strain amplitude of 10%, and 5 points per 10 points. Frequency sweep experiments were performed using a TA Instruments DHR3 stress-controlled rheometer with a cone angle of 5°, a truncated head of 137 μm, and a conical plate shape with a diameter of 25 mm. In these experiments, sinusoidal strain waves were applied, and the stress response was analyzed in terms of linear viscoelastic functions. The zero shear rate viscosity (η0) based on the DMA frequency sweep results was predicted by the Ellis model (see RBBird et al., "Dynamics of Polymer Liquids. Volume 1: Fluid Mechanics," Wiley-Interscience Publications (1987), p. 228) or the Carreau-Yasuda model (see K. Yasuda (1979) PhD Thesis, IT Cambridge). Dynamic rheological data was analyzed using rheometer software (i.e., Rheometrics RHIOS V4.4 or Orchestrator Software) to determine the melt modulus G'(G''=500) at a reference melt viscosity (G'') value of G''=500 Pa. Where necessary, values ​​were obtained by interpolation between available data points using Rheometrics software. The term "storage modulus" G'(co), also called "modulus," is a function of the applied frequency co and is defined as the stress in phase with the strain in sinusoidal deformation divided by the strain. On the other hand, the term "viscosity" G''(ω), also called "loss modulus," is similarly a function of the applied frequency ω and is defined as the stress out of phase with the strain divided by the strain. These moduli of elasticity, as well as other linear viscoelastic and dynamic rheological parameters, are well known to those skilled in the art, for example, as discussed by G. Marin in Chapter 10, "Oscillatory Rheometry," of "Oscillatory Rheometry" edited by A.A.Collyer and D.W.C.Legg (Rheological Measurement, Elsevier, 1988).

[0244] Shear viscosity index SHI (1,100) This was calculated as the ratio of the complex viscosity estimated at a shear stress of 1 kPa to the complex viscosity estimated at a shear stress of 100 kPa. Shear viscosity reduction index SHI (1,100) This provides information on the shear viscosity reduction behavior of polymer molten materials. High values ​​indicate a strong dependence of viscosity on changes in deformation rate (shear or frequency).

[0245] The evaluation of the relative modulus is based on measurements performed at low frequencies best suited to the conditions related to powder sintering and densification in rotational molding. The relative modulus was evaluated based on the ratio of G' to G'' at a frequency of 0.05 rad / s (or 0.5 rad / s) from DMA frequency sweep measurements performed at 190°C. Data reported in the literature indicate that resin compositions with high relative moduli tend to be difficult to process due to slow powder densification. Wang and Kontopoulou reported suitable rotational moldability for a blend composition characterized by a high relative modulus of 0.125 (2004). Their study investigated the effect of plastomer content on the rotational moldability of polypropylene (WQ Wang and M. Kontopoulou (2004) Polymer Engineering and Science, Vol. 44, No. 9, pp. 1662-1669). Further analysis of the results published by Wang and Kontopoulou shows that compositions with higher plastomer content exhibit an increased relative modulus (G' / G'' > 0.13), and correspondingly, it becomes more difficult to achieve complete densification during rotational molding evaluation.

[0246] In this disclosure, the LCBF (Long Chain Branching Factor) was determined using η0 obtained by DMA (see U.S. Patent No. 10,442,921).

[0247] <Melting Strength> Melt strength is measured at 190°C using a Rosand RH-7 capillary rheometer (barrel diameter = 15 mm) with a 2 mm diameter flat die and an L / D ratio of 10:1. Pressure transducer: 10,000 psi (68.95 MPa). Piston speed: 5.33 mm / min. Conveying angle: 52°. Incremental conveying rate: 50-80 m / min 2 or 65±15m / min 2 The polymer molten material is extruded through a capillary die at a constant rate, and the polymer strand is then drawn out at an increasing transport rate until it bursts. The maximum steady-state value of the force in the plateau region of the force-time curve is defined as the melt strength of the polymer. The melt strength elongation ratio is defined as the ratio of the velocity at the pulley to the velocity at the die exit.

[0248] <Long-chain branching coefficient (LCBF)> LCBF (dimensionless) was determined for polyethylene compositions using the method described in U.S. Patent No. 10,442,921, which is incorporated herein by reference.

[0249] The calculation of the long-chain branching coefficient ("LCBF") involves multi-dispersion-corrected zero shear viscosity (ZSV), as detailed in the following paragraphs. c ) and short-chain branched ("SCB") corrected intrinsic viscosity (IV c ) is necessary.

[0250] Zero shear viscosity (ZSV) with dimensions of Poise c The correction for ) was made as shown in equation (1):

number

[0251] Intrinsic viscosity (IV) with dimensions of dL / g c The correction for ) was made as shown in equation (2):

number

[0252] A "linear" ethylene copolymer (or linear ethylene homopolymer) that does not contain LCB or contains LCB at undetectable levels lies on the baseline defined by formula (3).

number

[0253] The LCBF is calculated by the following formula, which defines the horizontal shift (S) from the linear baseline. h ) and vertical shift (S v ) was done based on:

number

number

[0254] In equations (4) and (5), ZSV c and IV c However, each must have dimensions of poise and dL / g. Horizontal shift (S h ) is the intrinsic viscosity (IV c ZSV when ) is constant c It is a shift of , and if we remove the log function, its physical meaning becomes clear. That is, it is the ratio of two zero shear viscosities, and the same IV c ZSV of linear ethylene copolymer (or linear ethylene homopolymer) having c ZSV of the test sample c This is the horizontal shift (S h ) was dimensionless. Vertical shift (S v ) is zero shear viscosity (ZSV). c IV when ) is constant c It is a shift, and if we remove the log function, its physical meaning becomes clear. That is, it is the ratio of the two intrinsic viscosities, and the IV of the test sample. c For the same ZSV c IV of a linear ethylene copolymer (or linear ethylene homopolymer) having c This is the vertical shift (S v ) was dimensionless.

[0255] The dimensionless long-chain branching coefficient (LCBF) was defined by equation (6):

number

[0256] In one embodiment of the present disclosure, an ethylene polymer having LCB (e.g., a polyethylene composition) is characterized by having an LCBF (dimensionless) of 0.0010 or greater; in contrast, an ethylene polymer without LCB (or in which LCB cannot be detected) is characterized by having an LCBF (dimensionless) of less than 0.0010.

[0257] <Impact properties> The IZOD impact performance was determined according to ASTM D256. The IZOD impact specimens were notched to promote stress concentration points that induce brittle fracture rather than ductile fracture. The tensile impact performance was determined according to ASTM D1822.

[0258] <Tensile properties> The following tensile properties were determined using ASTM D638: yield elongation (%), yield strength (MPa), ultimate elongation (%), ultimate strength (MPa), and 1% and 2% secant modulus (MPa).

[0259] <Bending properties> The bending properties, specifically the 2% secant modulus of the bending wire, were determined using ASTM D790-10 (published April 2010).

[0260] <Environmental Stress Crack Resistance (ESCR)> Plaques molded from polyethylene compositions were tested according to the following ASTM method: Bending strip environmental stress crack resistance (ESCR), ASTM D1693; ESCR test under ASTM D1693 "B" conditions (temperature 50°C) was performed using IGEPAL CO-630 (nonylphenoxypoly(ethyleneoxy)ethanol, branched; formula: 4-(branched C9H 19 )-phenyl-[OCH2CH2] n The test was conducted using a 100% solution of (containing -OH, where the subscript n is 9-10) and a 10% solution of IGEPAL CO-630. A person skilled in the art would know that the test using the 10% solution ("B 10 ") is a test using a 100% solution ("B 100 Something more difficult than ""), namely, B 10 The value of is typically B 100 You will notice that it is lower than the value.

[0261] Plaques molded from polyethylene compositions were tested according to the following ASTM method: Bending strip environmental stress crack resistance (ESCR), ASTM D1693; ESCR test under ASTM D1693 "A" conditions (temperature 50°C) was performed using IGEPAL CO-630 (nonylphenoxypoly(ethyleneoxy)ethanol, branched; formula: 4-(branched C9H 19 )-phenyl-[OCH2CH2] n The test was conducted using a 100% solution of (containing -OH, where the subscript n is 9 to 10) and a 10% solution of IGEPAL CO-630. A person skilled in the art would know that the test using the 10% solution ("A 10 ") is a test using a 100% solution ("A 100 Something more difficult than "), namely, A 10 The value of is typically A 100 You will notice that it is lower than the value.

[0262] <Preparation of polyethylene composition> The polyethylene composition was prepared using a mixed binary catalyst system in an "in-series" double reactor solution polymerization process. As a result, the polyethylene composition contained a first ethylene copolymer prepared with a single-site catalyst and a second ethylene copolymer prepared with a multi-site catalyst. A "in-series" double reactor, solution-phase polymerization process, including one using a mixed binary catalyst, is described in U.S. Patent Application Publication 2018 / 0305531. Essentially, in the "in-series" double reactor system, the outlet flow from the first polymerization reactor (R1) flows directly into the second polymerization reactor (R2). The pressure in R1 was approximately 14 MPa to 18 MPa, while R2 was operated at a lower pressure to facilitate continuous flow from R1 to R2. Both R1 and R2 were continuous stirred reactors (CSTRs) and stirred under conditions that ensured thorough mixing of the reactor contents. The process was operated continuously by supplying fresh process solvent, ethylene, 1-octene, and hydrogen to the reactors and removing the product. Note that in the examples of this invention, fresh 1-octene is supplied to both the first and second reactors (R1 and R2) (in fact, in Examples 1-3, more 1-octene is supplied to the second reactor than to the first). Methylpentane was used as the process solvent (a commercially available blend of methylpentane isomers). The volume of the first CSTR reactor (R1) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). The monomer (ethylene) and comonomer (1-octene) were purified using a conventional feed preparation system (such as contact with various absorption media to remove impurities such as water, oxygen, and polar contaminants) before being added to the reactors. The reactor feed was pumped into the reactors in the ratios shown in Table 1. The average residence time in a reactor is calculated by dividing the average flow rate by the reactor volume and is primarily influenced by the amount of solvent flowing through each reactor and the total amount of solvent flowing through the solution process.

[0263] In the first reactor (R1), the first ethylene copolymer was prepared using the following single-site catalyst components: diphenylmethylene (cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dimethyl [(2,7-tBu2Flu)Ph2C(Cp)HfMe2]; methylaluminoxane (MMAO-07); trityltetrakis(pentafluorophenyl)borate (tritylborate); and 2,6-di-tert-butyl-4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07) and 2,6-di-tert-butyl-4-ethylphenol were pre-mixed in-line and combined with diphenylmethylene (cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dimethyl and trityltetrakis(pentafluorophenyl)borate immediately before entering the polymerization reactor (R1). The efficiency of the single-site catalyst formulation was optimized by adjusting the molar ratio of the catalyst components and the R1 catalyst inlet temperature.

[0264] The second ethylene copolymer was prepared in a second reactor (R2) using the following Ziegler-Natta (Zn) catalyst components: butylethylmagnesium; tertiary butyl chloride; titanium tetrachloride; diethylaluminum ethoxide; and triethylaluminum. Using methylpentane as the catalyst solvent, an in-line Ziegler-Natta catalyst formulation was prepared using the following steps and then injected into the second reactor (R2). In step 1, a solution of triethylaluminum and butylethylmagnesium (Mg:Al=20, molars:molars) was mixed with a solution of tertiary butyl chloride and reacted for approximately 30 seconds to produce a MgCl2 support. In step 2, a solution of titanium tetrachloride was added to the mixture formed in step 1 and reacted for approximately 14 seconds before being injected into the second reactor (R2). The in-line Ziegler-Natta catalyst was activated in the reactor by injecting a solution of diethylaluminum ethoxide into R2. The amount of titanium tetrachloride added to the reactor is shown in Table 1. The efficiency of the in-line Ziegler-Natta catalyst formulation was optimized by adjusting the molar ratio of the catalyst components.

[0265] Polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the second reactor outlet flow. The catalyst deactivator used was octanoic acid (caprylic acid), commercially available from P&G Chemicals (Cincinnati, Ohio, USA). The catalyst deactivator was added so that the moles of the fatty acid added amounted to 50% of the total molar amount of hafnium, titanium, and aluminum added to the polymerization process; for clarity, the moles of added octanoic acid = 0.5 × (moles of hafnium + moles of titanium + moles of aluminum).

[0266] The ethylene interpolymer product was recovered from the process solvent using a two-stage defoliation process. Specifically, two vapor / liquid separators were used to pass the second bottom flow (from the second V / L separator) through a gear pump / pelletizer combination. DHT-4V® (hydrotalcite), supplied by Kyowa Chemical Industry Co., Ltd. (Tokyo, Japan), was used as a passivator or acid scavenger in the continuous solution process. A slurry of DHT-4V in the process solvent was added before the first V / L separator.

[0267] Before pelletizing, the polyethylene composition was stabilized by adding approximately 500 ppm of IRGANOX1076 (primary antioxidant) and approximately 500 ppm of IRGAFOS168 (secondary antioxidant) based on the weight of the polyethylene composition. The antioxidants were dissolved in a process solvent and added between the first V / L separator and the second V / L separator.

[0268] Table 1 shows the reactor conditions used to prepare the polyethylene compositions of the present invention (Examples 1, 2, 3, 4, 5, and 6). Table 1 includes process parameters such as ethylene split and 1-octene split between reactors (R1 and R2), reactor temperature, and ethylene conversion rate. Table 1 also shows the reactor conditions used to prepare comparative polyethylene compositions. The comparative compositions (Examples 7, 8, 9, 10, 11, and 12) were also prepared using a double reactor process, but different polymerization catalysts were used in the first and second reactors (see Table 1).

[0269] Comparative Example 7 was prepared substantially in accordance with U.S. Patent Application No. 63 / 153,311. During the preparation of Comparative Example 7, a mixed single-site catalyst system was used in a double reactor process: in the first reactor, a cross-linked metallocene single-site catalyst [(2,7-tBu2Flu)Ph2C(Cp))HfMe2], known to induce long-chain branching, was used, and in the second reactor, a phosphine imine single-site catalyst Cp[(t-Bu)3PN]TiCl2, known not to induce long-chain branching, was used.

[0270] Comparative Examples 8, 10, and 11 were prepared substantially in accordance with International Publication No. 2021 / 214584. In the preparation of Comparative Examples 8, 10, and 11, a mixed catalyst system was used in a double reactor process: in the first reactor, a phosphine imine single-site catalyst Cp[(t-Bu)3PN]TiCl2, known not to induce long-chain branching, was used; and in the second reactor, a Ziegler-Natta catalyst, also known not to induce long-chain branching, was used.

[0271] Comparative Example 9 was prepared substantially in accordance with U.S. Patent No. 10,023,706. The preparation of Comparative Example 9 involved a mixed catalyst system in a double reactor process: a phosphine imine single-site catalyst Cp[(t-Bu)3PN]TiCl2, known to not induce long-chain branching, was used in the first reactor, and a Ziegler-Natta catalyst, also known to not induce long-chain branching, was used in the second reactor.

[0272] Comparative Example 12 was prepared substantially in accordance with International Publication No. 2020 / 240401. In the preparation of Comparative Example 12, the phosphine imine single-site catalyst Cp[(t-Bu)3PN]TiCl2, which is known not to cause long-chain branching, was used in both the first and second reactors of a double reactor process.

[0273] [Table 1-1]

[0274] [Table 1-2]

[0275] Table 2 shows the properties of polyethylene compositions manufactured in accordance with this disclosure and prepared according to Examples 1 to 6 above. Table 2 also includes data for several comparative polyethylene compositions prepared according to Examples 7 to 12, as well as Examples 13 and 14 above. Example 13 is ROTOTUF® RT748, which is commercially available from Ingenia Polymers. Example 14 is NOVAPOL® TR-0740-U, an ethylene copolymer prepared in the gas phase and commercially available from NOVA Chemicals Corporation.

[0276] [Table 2-1]

[0277] [Table 2-2]

[0278] [Table 2-3]

[0279] [Table 3-1]

[0280] [Table 3-2]

[0281] [Table 3-3]

[0282] Figure 1 shows that the polyethylene compositions of this disclosure (Examples 1-6) have a unimodal GPC profile, while Comparative Example 7 has a bimodal GPC profile.

[0283] Figure 2 shows that the polyethylene compositions of this disclosure (Examples 1-6) have a unimodal GPC-FTIR profile, and that the amount of comonomers increases as the molecular weight increases (indicated by the short-chain branching content, SCB / 1000 skeletal carbon atoms). Therefore, it can be said that the comonomer distribution of Examples 1-6 is inverted, and in fact, as shown in Figure 2, it is highly inverted (the curve showing SCB / 1000 carbons increases sharply with increasing molecular weight). In fact, in Examples 1-3, z The amount of short-chain branching in Mz (i.e., SCB / 1000 in Mz) is greater than 9, while the amount of short-chain branching in Mn (i.e., SCB / 1000C in Mn) is less than 3, which is consistent with highly inverted comonomer incorporation.

[0284] Figure 3 shows the temperature rise elution fractionation (CTREF-SLOW) profiles for polyethylene compositions (Examples 1-6) prepared according to this disclosure.

[0285] Figures 4A and 4B show viscosity profiles obtained from DMA frequency sweep experiments conducted at 190°C for the polyethylene compositions of this disclosure and several comparative examples. While we do not wish to be bound by theory, the shape of the viscosity profile, particularly the decrease in viscosity with increasing deformation rate, strongly influences the flow distribution and melt pressure requirements in extrusion and molding applications. Figure 4A clearly shows that Examples 1, 3, 4, and 6 of the present invention exhibit good shear viscosity reduction behavior, as viscosity decreases rapidly with increasing shear rate. This good shear viscosity reduction behavior is attributed to the high shear viscosity reduction index SHI observed in Examples 1, 3, 4, and 6. (1,100) While we do not wish to be bound by theory, as is evident from the above, the good shear viscosity reduction behavior is thought to be due to the presence of long-chain branching in Invention Examples 1, 3, 4, and 6. Good shear viscosity reduction behavior is advantageous in applications where extrusion speed is limited and in mold filling applications that typically require resins with high flowability. For resins with comparable molecular weight and molecular weight distribution, lower viscosity at higher deformation speeds means that the resin is easier to process, requiring lower temperatures and extruder torque to achieve high throughput through the die. Similarly, resins exhibiting good shear viscosity reduction behavior require lower melting pressure and temperature to fill mold cavities. Viscosity can be reduced by lowering the molecular weight, but often at the expense of mechanical performance. As the data in Tables 2 and 3 and Figure 4A show, the polyethylene compositions of this disclosure (Invention Examples 1-6) have good mechanical performance characteristics (e.g., Izod impact, ESCR) that are typically associated with relatively high molecular weights, while also having high flowability characteristics (e.g., lower viscosity at higher shear rates).

[0286] Interestingly, the shear reduction behavior in Invention Examples 1 and 3 of this disclosure is more pronounced compared to Example 2. This enhanced shear reduction behavior is likely related to the increased long-chain branching in Invention Examples 1 and 3 compared to Invention Example 2. Also, while we do not wish to be bound by theory, an increase in the amount of shear reduction generally leads to improved throughput and / or a decrease in the required injection pressure / clamping force in molding processes such as injection molding.

[0287] As the data shown in Tables 2 and 3 indicate, compared to several comparative examples, the polyethylene composition of this disclosure has a good combination of a considerable amount of long-chain branching (LCBF greater than 0.0010), high rigidity (e.g., flexural secant modulus 1% > 900 MPa), very high impact resistance (e.g., IZOD impact > 9.0 ft-lb / in), and high environmental resistance (e.g., greater than 500 hours under ESCR condition B @ 100%), as well as good flow properties due to a relatively high melt index value (e.g., melt index I2 greater than 5 g / 10 min). Due to its high flowability, good rigidity, and good impact resistance and environmental stress resistance, the polyethylene composition of this disclosure is useful, for example, in extrusion molding applications, injection molding applications, and in the manufacture of rotationally molded parts using rotational molding processes (including molding processes with complex mold designs (e.g., sharp angles, filled screws, etc.) and / or inserts).

[0288] As shown in Tables 1, 2, and 3, in contrast to Comparative Example 7, which was prepared using a mixed single-site catalyst platform, some of the polyethylene compositions of this disclosure exhibit a decrease in LCBF value, a decrease in relative modulus (defined as elastic ratio G' / G''@0.05 rad / s), a decrease in zero shear viscosity, and a decrease in melt flow ratio I 21 As indicated by the decrease in / I2, the amount of long-chain branching is reduced. While long-chain branching is considered beneficial for some polymer performance indicators, too much branching can degrade some polymer performance and rheological properties. For example, with regard to end applications in rotationally molded parts, reducing the amount of long-chain branching can be beneficial because it can worsen sintering and powder densification. The data shown in Table 4 (see below) confirms this and suggests that the reduced amount of long-chain branching present in the polyethylene compositions of this disclosure may be beneficial for rotational molding processes.

[0289] Furthermore, it is noteworthy that the melt strength of Invention Examples 4, 5, and 6 is higher than that of Comparative Example 7 (and Comparative Example 14). Although we do not wish to be bound by theory, Invention Examples 4, 5, and 6 have similar Mw / Mn values ​​compared to Comparative Example 7, and exhibit low LCBF and low MFR (I 21 Although the amount of long-chain branching is small, as shown by / I2), polyethylene compositions with higher melt strength can be obtained by using a mixed catalyst system (e.g., a metallocene / Zn catalyst system) instead of an all-single-site catalyst system (e.g., a metallocene / phosphineimine catalyst system).

[0290] <Polyethylene composition formulation> Using a melt extrusion method, various additives were blended into polyethylene compositions, and their rotational molding performance was evaluated. The blended polyethylene compositions were pulverized to a fine powder (35 mesh) before being used for molding rotational molded parts. The final blended compositions included UV (ultraviolet) protection additives, as well as primary and secondary antioxidants.

[0291] The compounded polyethylene compositions of Examples 1, 2, and 3 were prepared by melt-blending the additives in the form of a masterbatch using a Leistritz LSM 30.34 twin-screw extruder. The compounded polyethylene composition of Example 4 was prepared by melt-blending the additives in the form of a masterbatch using a single-screw 3-inch EGAN. The compounded polyethylene composition of Example 6 was prepared by melt-blending the additives in the form of a masterbatch using a twin-screw compounding line (Coperion ZSK26). In Examples 1 to 3, the polyethylene composition (96.5% by weight) was tumble-blended with a polyethylene composition masterbatch (3.5% by weight). In Examples 4 to 6, the polyethylene composition (97.7% by weight) was tumble-blended with a polyethylene composition masterbatch (2.3% by weight). The compounded comparative resins (Examples 7, 10, and 11) were prepared similarly, and the comparative resins (Examples 13 and 14) were used as is. The final polyethylene composition contained hindered phenol (IRGANOX1076), phosphite (IRGAFOS168), zinc oxide, HALS TINUVIN 622, HALS CHIMASSORB 944, diphosphite DOVERPHOS 9228, and hydroxylamine IRGASTAB FS042.

[0292] Prior to rotational molding, the compounded polyethylene composition of this disclosure and a comparative resin were passed through a pulverizer to produce a polyethylene composition powder having a mesh size of 35 US (mesh opening of 0.0197 inches (500 μm)).

[0293] <Preparation of rotationally molded parts> The powdered polyethylene composition was converted into rotational molded parts using a rotational molding machine. Specifically, a ROTOSPEED RS160 available from Ferry Industries Inc. (Stow, Ohio, USA) was used. The ROTOSPEED has two arms that rotate about a central axis within a sealed oven. A plate is attached to the arm, and this plate rotates about an axis that is approximately perpendicular to the axis of rotation of the arm. Six cast aluminum molds are attached to each arm to produce hollow rotational molded parts in a cube shape (i.e., 12.5 inches (31.8 cm) × 12.5 inches × 12.5 inches). The rotation of the arm was set at approximately 8 revolutions per minute (rpm), and the rotation of the plate was set at approximately 2 rpm. Using a polyethylene composition in powder form with a standard fill weight of approximately 3.7 kg, rotational molded parts with a nominal thickness of approximately 0.250 inches (0.64 cm) were produced. The powder used had a 35 US mesh size (opening 0.0197 inches (500 μm)). The temperature inside the sealed oven was maintained at 560°F (293°C). The molds and their contents were heated in the oven for 16, 18, 20, 22 minutes so that the powder was completely densified. Then, before removing the parts from the molds, the molds were cooled using an air fan for approximately 30 minutes. After removing the plastic parts from the molds, the parts were kept at room temperature for at least 24 hours and then cut to collect test specimens for subsequent tests. Test specimens were collected from the molded parts, the density was evaluated, and an ARM impact test was conducted. The results are shown in Table 4, Figures 5, 6, 7A, 7B.

[0294] <ARM Impact Test> The ARM impact test was conducted in accordance with ASTM D5628 at a test temperature of -40°C. This test was based on the Low Temperature Impact Test version 4.0 (July 2003) of the Association of Rotational Molders International. The purpose of this test was to investigate the impact properties of rotationally molded parts. The ARM impact test specimens (5 inches x 5 inches, 12.7 cm x 12.7 cm) were cut from the sidewall of a cubic rotationally molded part. The specimens were thermally equilibrated in a refrigerated test laboratory maintained at -40°F ± 3.5°F (-40°C ± 2°C) for at least 24 hours prior to the impact test. The test method employed is commonly known as the Bruceton step method or up-and-down method. In this procedure, a specific dart height is set at which 50% of the specimen will break. In other words, the test of dropping darts onto the specimen was continued until at least 10 passes and 10 failures (failures) were obtained. Each fracture was characterized as either ductile or brittle fracture. Ductile fracture was characterized by the dart penetrating the specimen, the impact area stretching and thinning, and a thread-like hole remaining at the fracture point. Brittle fracture was evident when a crack formed in the specimen, the crack radiating outward from the fracture point, and the specimen stretching little to no at the fracture point. The "ARM ductility" was calculated using the following formula: 100% × [(number of ductile fractures) / (total number of fractures)].

[0295] The samples were subjected to impact testing using a drop impact testing machine. The available impact darts consisted of 10-pound (4.54 kg), 15-pound (6.80 kg), 20-pound (9.07 kg), or 30-pound (13.6 kg) darts. All impact darts featured a round dart tip with a diameter of 1.0 ± 0.005 inches (2.54 cm), transitioning into a lower cylindrical shaft (1.0 inch in diameter), with the lower cylindrical shaft (to the dart tip) measuring 4.5 inches (11.4 cm). The impact darts included an upper cylindrical shaft with a diameter of 2.0 inches (5.08 cm), the length of which varied depending on the desired weight of the dart. For example, for 10-pound or 20-pound darts, the length was 10.5 inches (26.7 cm) or 16.5 inches (41.9 cm), respectively. Preferably, the weight of the dart was selected so that the drop height was between 2.5 feet and 7.5 feet (0.8 m to 2.3 m). The test specimen was positioned in an impact testing machine so that the falling dart would strike the surface of the part that had been in contact with the mold (during molding). If the specimen did not break at a given height and weight, either the height or the weight was gradually increased until the part broke. If breakage occurred, the height or weight was decreased by the same amount, and this process was repeated. The "ARM mean fracture energy (ft·lbs)" was calculated by multiplying the drop height (ft) by the nominal dart weight (lbs). After impact, both the top and bottom surfaces of the test specimen were inspected for fracture. For the polyethylene compositions disclosed herein, ductile fracture was the preferred mode of fracture.

[0296] [Table 4-1]

[0297] [Table 4-2]

[0298] Figures 5, 6, 7A, and 7B show the rotational molding performance of the polyethylene compositions of this disclosure (Examples 1, 2, 3, 4, and 6) and several comparative examples (Examples 10, 11, 13, and 14).

[0299] Good rotational molding processability is achieved when the polymer resin can achieve a high average fracture energy value and high ductility under a wide range of rotational molding conditions (e.g., a wide range of oven times at a given oven temperature). It is also desirable for the polymer resin to exhibit good powder densification properties, which basically means that the resin can be rotationally molded without forming excessive void inclusions, which can adversely affect the impact properties of rotationally molded parts. In this disclosure, an index comparing the density of the virgin polymer with the density of the rotationally molded part was used as an index to evaluate powder densification. A significant decrease in the density of the rotationally molded part compared to the virgin polymer is undesirable, as this indicates insufficient powder densification and the presence of voids in the rotationally molded part. The density delta in Figure 5 is defined as the difference between the plaque density determined from ASTM D792 and the density of the rotationally molded test specimen (sometimes called "density-as-is"). "The density as is" is measured using a density gradient column at 23°C on a rotationally molded specimen, in accordance with ASTM D1505-18.

[0300] As can be seen from Figure 5, Invention Examples 1, 2, and 3 all exhibit good powder densification properties when used in the manufacture of rotationally molded parts. Comparative Examples 10, 11, and 13 also show good performance in this metric, while Invention Examples 4 and 6, and Comparative Example 14, may have the lowest densification properties when rotationally molded. Therefore, although Invention Examples 1-6 all have a good balance of properties useful for rotational molding applications, Examples 1-3, particularly Examples 2 and 3, also show improved powder densification properties. We do not wish to be bound by theory, but this may be due to the low number of long-chain branches in these particular polyethylene compositions.

[0301] As can be seen from Figure 6, among Invention Examples 1, 2, 3, 4, and 6, Examples 2 and 3 in particular exhibit very good ARM impact resistance over a wide range of oven processing times. Comparative Examples 10, 11, and 13 also show good ARM impact resistance over a wide range of oven processing times. In contrast, the ARM impact data obtained for Invention Examples 1, 4, and 6 are consistent with the narrow oven processing time window of these polyethylene compositions. Comparative Example 14 showed the lowest performance in terms of ARM impact values ​​measured over a wide range of oven processing times. While we do not wish to be bound by theory, the very good rotational molding processing time window observed in Invention Examples 2 and 3 with respect to ARM impact resistance may be due to fewer long-chain branching in these particular polyethylene compositions. Invention Examples 2 and 3 also had high maximum ARM impact mean fracture energies of 174 ft.lb and 203 ft.lb, respectively (see Figure 6 and Table 4).

[0302] As can be seen from Figure 7A, among Invention Examples 1, 2, 3, 4, and 6, Examples 2 and 3 exhibited very good ductility over a wide range of oven processing times. As shown in Figure 7B, Comparative Examples 10, 11, and 13 also exhibited good ductility over a wide range of oven processing times. In contrast, the ARM ductility data obtained for Invention Example 1 is consistent with the narrow oven processing time window of this polyethylene composition. Invention Examples 4 and 6, and Comparative Example 14, exhibited the lowest performance with respect to ductility measured over a wide range of oven processing times. While we do not wish to be bound by theory, the very good rotational molding processing time window observed in Invention Examples 2 and 3 with respect to ARM ductility may be due to the low number of long-chain branching in these particular polyethylene compositions. Invention Examples 2 and 3 also had high maximum ductility of 100% and 100%, respectively (see Figure 7A and Table 4).

[0303] Considering the data shown in Tables 2, 3, and 4, and the data shown in Figures 5, 6, and 7, these data indicate that the polyethylene compositions of the present invention have a good balance of ESCR, IZOD impact, and high fluidity (see data for Examples 1 to 6 in Tables 2 and 3). Furthermore, some of the polyethylene compositions of the present invention also have very good processing characteristics specific to rotational molding, namely a good rotational molding oven time processing window for ARM impact mean fracture energy and ductility (see data for Examples 2 and 3 in Table 4). Therefore, the polyethylene compositions of Invention Example 2 and Invention Example 3 may be particularly useful for forming rotationally molded parts.

[0304] While we do not wish to be bound by theory, the improvement in rotational moldability observed in Invention Example 2 and Invention Example 3 compared to other examples is thought to be due to the difference in long-chain branching content. The presence of long-chain branching can adversely affect the rheology (zero shear viscosity, relative modulus) of the polyethylene composition at low frequencies, and these rheological properties control the sintering of the powder. Poor powder sintering behavior can lead to the formation of larger bubbles, an increase in defects in rotationally molded parts, and even a decrease in mechanical performance characteristics.

[0305] A simple method for evaluating the melt rheology of polyethylene compositions may be based on a small-amplitude frequency sweep test. The obtained rheological results are the complex modulus G. * It is expressed as a phase angle δ (degrees) as a function of (Pascal), and is known to those skilled in the art as the van Gurp-Palmen plot (described in M. Van Gurp, J. Palmen, Rheol. Bull., 1998, 67(1): pp. 5-8, and Dealy J, Plazek D., Rheol. Bull., 2009, 78(2): pp. 16-31). In typical polyethylene, G * As the VGP becomes sufficiently low, the phase angle δ increases toward the upper limit of 90°. A typical VGP plot is shown in Figure 4 of U.S. Patent Application Publication 2018 / 0298170, which is incorporated herein in its entirety. The VGP plot is characteristic of the resin structure. In ideally linear monodisperse polyethylene, δ increases monotonically toward 90°. For branched polyethylene or blends containing branched polyethylene, δ(G * ) may show inflection points that reflect the topology of branched polyethylene (see S. Trinkle, P. Walter, C. Friedrich, Rheo. Acta, 2002, 41:103-113). A deviation from the monotonically increasing phase angle δ may indicate a deviation from ideal linear polyethylene, either due to the presence of long-chain branching or the presence of a blend containing at least two ethylene copolymers with different branching structures.

[0306] The level of long-chain branching present in Invention Examples 2 and 3 differs from that in Invention Examples 1, 4, 5, and 6, as further demonstrated by the observable differences in the Van Gurp Palmen (VGP) plot (Figure 8A), which may be considered in conjunction with the relative modulus (defined as the elastic ratio G' / G''@0.5 (rad / s) and / or G' / G''@0.05 (rad / s)), zero-shear viscosity, and melt flow ratio already mentioned above. Those skilled in the art will recognize, by examining the VGP plot, that the amount of long-chain branching is particularly low in Example 2, which is consistent with improved processing performance of the rotationally molded part. Again, this data indicates that while long-chain branching is present in all Invention Examples 1 through 6, too much branching can negatively affect sintering and powder densification during the rotational molding process.

[0307] Considering the data shown in Tables 3 and 4 and Figure 8A together, these data suggest that there is an optimal amount of long-chain branching (and in fact, a maximum amount) for achieving good rotational moldability when designing polyethylene compositions having a predetermined density and melt index range in accordance with this disclosure. Furthermore, with respect to rotational moldability, polyethylene compositions having a predetermined phase angle δ in the VGP plot have relative modulus G' / G''@0.05 and complex modulus G * An optimal (and maximum) value may also exist (however, if the amount of long-chain branching present in the polyethylene composition is large, G may be a given value of δ). * (It is expected to be even lower.)

[0308] <Deconvolution of polyethylene compositions> Mathematical deconvolution was performed to determine the relative amounts of the first and second ethylene copolymers present in the polyethylene composition, and the molecular weights (Mw, Mn, Mz) and comonomer content (SCB frequency per 1000 carbon atoms in the polymer skeleton) of the first and second ethylene copolymers produced in the first and second reactors (R1 and R2) were determined.

[0309] In the deconvolution calculations, it was assumed that the single-site catalyzed ethylene copolymer component follows the Flory molecular weight distribution function and has a uniform comonomer distribution across the entire molecular weight range.

[0310] The estimates were first obtained from predictions using a basic kinetic model with kinetic constants specific to each catalyst formulation, as well as the feedstock and reactor conditions. This simulation is based on the configuration of the solution pilot plant described above, which was used to produce the polyethylene compositions disclosed herein. Using the predictions of the kinetic model, estimates of the short-chain branching distribution in the first and second ethylene copolymer components were established. The estimates of the short-chain branching content were also validated against experimental results obtained from GPC-FTIR for the comonomer distribution. The fit between the simulated molecular weight distribution profiles and the actual data obtained from GPC chromatography was improved by modeling the molecular weight distribution as the sum of components having molecular weight distributions described using a multi-site idealized Flory distribution.

[0311] During deconvolution, the total Mn, Mw, and Mz are calculated using the following relationship: Mn = 1 / Σ(w i / (Mn) i ),Mw=Σ(w i x(Mw) i ), Mz=Σ(w i x(Mz) i 2 / Σ(w i x(Mz i In the formula, i represents the i-th component, and wi represents the relative weight fraction of the i-th component in the composition.

[0312] The density and melt index I2 of each ethylene copolymer component were calculated using the following formula:

number

number

number

[0313] [Table 5-1]

[0314] [Table 5-2]

[0315] Non-limiting embodiments of this disclosure include:

[0316] Embodiment A. A polyethylene composition, (i) 0.880~0.930 g / cm³ 3 Density, molecular weight distribution M (1.7-2.7) w / M n , and weight-average molecular weight M of 75,000 to 250,000 g / mol w A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945~0.965 g / cm³ 3 Density, molecular weight distribution M 2.1~3.5 w / M n , and weight-average molecular weight M of 15,000 to 75,000 g / mol w Having 90-40 weight percent of a second ethylene copolymer and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.0. The polyethylene composition contains 0.942 g / cm³ 3 Density above 5.0 g / 10 min, melt index I2 above 5.0 g / 10 min, melt flow ratio I2 below 50. 21 A polyethylene composition having / I2 and a long-chain branching coefficient LCBF of 0.0010 or higher.

[0317] Embodiment B. The polyethylene composition according to Embodiment A, wherein the polyethylene composition has an LCBF of 0.0010 to 0.0090.

[0318] Embodiment C. The polyethylene composition according to Embodiment A, wherein the polyethylene composition has an LCBF of less than 0.0060.

[0319] Embodiment D. The polyethylene composition has a melt flow ratio I greater than 32. 21 A polyethylene composition according to Embodiment A, B, or C, having / I2.

[0320] Embodiment E. A polyethylene composition having a melt flow ratio of 15 to 32. 21 A polyethylene composition according to Embodiment A, B, or C, having / I2.

[0321] Embodiment F. A polyethylene composition with a molecular weight distribution M of 2.0 to 4.5. w / M n A polyethylene composition according to Embodiment A, B, C, D, or E, having the following characteristics.

[0322] Embodiment G. A polyethylene composition with a molecular weight distribution of less than 3.0 w / M n A polyethylene composition according to Embodiment A, B, C, D, or E, having the following characteristics.

[0323] Embodiment H. The polyethylene composition according to Embodiments A, B, C, D, E, F, or G, wherein the polyethylene composition has a unimodal profile in GPC analysis.

[0324] Embodiment I. The density of the first ethylene copolymer is 0.890 to 0.920 g / cm³. 3 The polyethylene composition according to Embodiments A, B, C, D, E, F, G, or H.

[0325] Embodiment J. The density of the first ethylene copolymer is 0.918 g / cm³. 3 A polyethylene composition according to Embodiments A, B, C, D, E, F, G, or H, which is less than [amount missing].

[0326] Embodiment K. The polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, or J, wherein the melt index I2 of the first ethylene copolymer is less than 1.0 g / 10 min.

[0327] Embodiment L. The polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, or K, wherein the melt index I2 of the second ethylene copolymer is 20.0 g / 10 min or more.

[0328] Embodiment M. The polyethylene composition is 0.942 to 0.950 g / cm³ 3 A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, or L, having a density of the above.

[0329] Embodiment N. The polyethylene composition is 0.943 to 0.950 g / cm³ 3 A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, or L, having a density of the above.

[0330] Embodiment O. The polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or N, wherein the polyethylene composition has a melt index I2 greater than 5.5 g / 10 min.

[0331] Embodiment P. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or N, wherein the polyethylene composition has a melt index I2 of 5.5 to 12.0 g / 10 min.

[0332] Embodiment Q. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or N, wherein the polyethylene composition has a melt index I2 of 5.5 to 10.0 g / 10 min.

[0333] Embodiment R. A polyethylene composition with a high load melt index I greater than 150 g / 10 min 21 A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, or Q, having the following characteristics.

[0334] Embodiment S. A polyethylene composition with a high-load melt index of 150-400 g / 10 min. 21 A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, or Q, having the following characteristics.

[0335] Embodiment T. A polyethylene composition with a high-load melt index of 150-225 g / 10 min 21 A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, or Q, having the following characteristics.

[0336] Embodiment U. A polyethylene composition having a weight-average molecular weight M of 45,000 to 80,000 g / mol. w A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, or T, having the following characteristics.

[0337] Embodiment V. The polyethylene composition has a number average molecular weight M of 10,000 to 35,000 g / mol. n A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, or U, having the following characteristics.

[0338] Embodiment W. The polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, or V, wherein the polyethylene composition contains 0.0015 to 2.4 ppm of hafnium.

[0339] Embodiment X. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, or W, wherein the first ethylene copolymer has 5 to 30 short-chain branched SCB1 / 1000C per 1000 carbon atoms.

[0340] Embodiment Y. The polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, or X, wherein the second ethylene copolymer has 0.1 to 3 short-chain branched SCB2 / 1000C per 1000 carbon atoms.

[0341] Embodiment Z. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, or Y, wherein the ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 10.

[0342] Embodiment AA. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, M, N, O, P, Q, R, S, T, U, V, W, X, Y, or Z, having an environmental stress crack resistance (ESCR) of more than 500 hours (determined by ASTM D1693 in 100% IGEPAL CO-630 under condition B).

[0343] Embodiment BB. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, or AA, having an environmental stress crack resistance (ESCR) of more than 1000 hours (determined by ASTM D1693 in 100% IGEPAL CO-630 under condition B).

[0344] Embodiment CC. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, or BB, having an environmental stress crack resistance (ESCR) of more than 500 hours (determined by ASTM D1693 in 10% IGEPAL CO-630 under condition B).

[0345] Embodiment DD. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, or CC, having an environmental stress crack resistance (ESCR) of more than 1000 hours (determined by ASTM D1693 in 10% IGEPAL CO-630 under condition B).

[0346] Embodiment EE. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, CC, or DD, having an Izod impact value greater than 9.0 foot-pounds / inch.

[0347] Embodiment FF. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, CC, or DD, having an Izod impact value of at least 10.0 foot-pounds / inch.

[0348] Embodiment GG. A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, CC, DD, EE, or FF, wherein the elastic ratio G' / G'' at 0.5 rad / s is less than 0.17.

[0349] Embodiment HH: A polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, CC, DD, EE, FF, or GG, wherein the bending secant modulus at 1% is 900 MPa or more.

[0350] Embodiment II. A solution-phase polymerization process for producing a polyethylene composition, The solution-phase polymerization process is A step of polymerizing ethylene and alpha-olefin using a metallocene catalyst in a first reactor, The process involves polymerizing ethylene and alpha-olefin using a Ziegler-Natta catalyst in a second reactor. Includes, The first reactor and the second reactor are configured in series with each other. Polyethylene composition, (i) 0.880~0.930 g / cm³ 3 Density, molecular weight distribution M (1.7-2.7) w / M n , and weight-average molecular weight M of 75,000 to 250,000 g / mol w A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945~0.965 g / cm³ 3 Density, molecular weight distribution M 2.0~3.5 w / M n , and weight-average molecular weight M of 15,000 to 75,000 g / mol w Having 90-40 weight percent of a second ethylene copolymer and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.0. The polyethylene composition contains 0.942 g / cm³ 3 Density above 5.0 g / 10 min, melt index I2 above 5.0 g / 10 min, melt flow ratio I2 below 50. 21 A solution-phase polymerization process having / I2 and a long-chain branching coefficient LCBF of 0.0010 or greater.

[0351] Embodiment JJ. A rotationally molded article prepared from a polyethylene composition, Polyethylene composition, (i) 0.880~0.930 g / cm³ 3 Density, molecular weight distribution M (1.7-2.7) w / M n , and weight-average molecular weight M of 75,000 to 250,000 g / mol w A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945~0.965 g / cm³ 3 Density, molecular weight distribution M 2.0~3.5 w / M n , and weight-average molecular weight M of 15,000 to 75,000 g / mol w Having 90-40 weight percent of a second ethylene copolymer and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.0. The polyethylene composition contains 0.942 g / cm³ 3 Density above 5.0 g / 10 min, melt index I2 above 5.0 g / 10 min, melt flow ratio I2 below 50. 21 A rotationally molded product having / I2 and a long-chain branching coefficient LCBF of 0.0010 or greater.

[0352] Embodiment KK. The rotational molded article according to Embodiment JJ, wherein the polyethylene composition contains an additive package comprising a hindered monophosphite, a diphosphite, a hindered amine light stabilizer, and at least one additional additive selected from the group consisting of hindered phenol and hydroxylamine. [Industrial applicability]

[0353] This disclosure relates to a solution-phase polymerization process, and a well-flowing, 0.942 g / cm³ polymerase. 3 This invention relates to polyethylene compositions having densities within the above range. The polyethylene compositions possess properties such as good environmental stress crack resistance and high IZOD impact strength, and can be suitably used for forming rotationally molded articles.

Claims

1. A polyethylene composition, (i) 0.880-0.930g / cm ３ Density, molecular weight distribution M between 1.7 and 2.7 ｗ / M ｎ , and weight-average molecular weight M of 75,000 to 250,000 g / mol ｗ A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945-0.965g / cm ３ Density, molecular weight distribution M between 2.1 and 3.5 ｗ / M ｎ , and weight-average molecular weight M of 15,000 to 75,000 g / mol ｗ A second ethylene copolymer having 90 to 40 weight percent and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.

0. The polyethylene composition has a density of 0.942 g / cm ３ or higher, a melt index I exceeding 5.0 g / 10 min ２ , a melt flow ratio I ２１ / I ２ of 50 or less, and a long-chain branching coefficient LCBF of 0.0010 or higher.

2. The polyethylene composition according to claim 1, wherein the polyethylene composition has an LCBF of 0.0010 to 0.0090.

3. A polyethylene composition with a melt flow ratio I greater than 32 ２１ / I ２ A polyethylene composition according to claim 1, having the following characteristics.

4. The polyethylene composition has a melt flow ratio of 15 to 32. ２１ / I ２ A polyethylene composition according to claim 1, having the following characteristics.

5. The polyethylene composition according to claim 1, wherein the polyethylene composition has an LCBF of less than 0.0060.

6. The polyethylene composition has a molecular weight distribution M of 2.0 to 4.

5. ｗ / M ｎ A polyethylene composition according to claim 1, having the following characteristics.

7. The polyethylene composition has a molecular weight distribution of less than 3.0 M ｗ / M ｎ A polyethylene composition according to claim 1, having the following characteristics.

8. The polyethylene composition according to claim 1, wherein the polyethylene composition has a unimodal profile in GPC analysis.

9. The density of the first ethylene copolymer is 0.890–0.920 g / cm³ ３ The polyethylene composition according to claim 1.

10. The density of the first ethylene copolymer is 0.918 g / cm³. ３ The polyethylene composition according to claim 1, wherein the amount is less than [amount missing].

11. Melt index I of the first ethylene copolymer ２ The polyethylene composition according to claim 1, wherein the amount is less than 1.0 g / 10 min.

12. Melt index I of the second ethylene copolymer ２ The polyethylene composition according to claim 1, wherein the amount is 20.0 g / 10 min or more.

13. The polyethylene composition is 0.942 to 0.950 g / cm³ ３ The polyethylene composition according to claim 1, having the density of .

14. The polyethylene composition is 0.943 to 0.950 g / cm³ ３ The polyethylene composition according to claim 1, having the density of .

15. The polyethylene composition has a melt index of I greater than 5.5 g / 10 min. ２ A polyethylene composition according to claim 1, having the following characteristics.

16. The polyethylene composition has a melt index of 5.5 to 12.0 g / 10 min. ２ A polyethylene composition according to claim 1, having the following characteristics.

17. The polyethylene composition has a melt index of 5.5 to 10.0 g / 10 min. ２ A polyethylene composition according to claim 1, having the following characteristics.

18. The polyethylene composition has a high-load melt index of I greater than 150 g / 10 min. ２１ A polyethylene composition according to claim 1, having the following characteristics.

19. The polyethylene composition has a high-load melt index of 150-400 g / 10 min. ２１ A polyethylene composition according to claim 1, having the following characteristics.

20. The polyethylene composition has a high-load melt index of 150-225 g / 10 min. ２１ A polyethylene composition according to claim 1, having the following characteristics.

21. The polyethylene composition has a weight-average molecular weight M of 45,000 to 80,000 g / mol. ｗ A polyethylene composition according to claim 1, having the following characteristics.

22. The polyethylene composition has a number average molecular weight M of 10,000 to 35,000 g / mol. ｎ A polyethylene composition according to claim 1, having the following characteristics.

23. The polyethylene composition according to claim 1, wherein the polyethylene composition contains 0.0015 to 2.4 ppm of hafnium.

24. The polyethylene composition according to claim 1, wherein the first ethylene copolymer has 5 to 30 short-chain branched SCB1 / 1000C atoms per 1000 carbon atoms.

25. The polyethylene composition according to claim 1, wherein the second ethylene copolymer has 0.1 to 3 short-chain branched SCB2 / 1000C per 1000 carbon atoms.

26. The polyethylene composition according to claim 1, wherein the ratio SCB1 / SCB2 of the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer is at least 10.

27. The polyethylene composition according to claim 1, having an environmental stress crack resistance (ESCR) of more than 500 hours (determined by ASTM D1693 under condition B in 100% IGEPAL CO-630).

28. The polyethylene composition according to claim 1, having an environmental stress crack resistance (ESCR) of more than 1000 hours (determined by ASTM D1693 under condition B in 100% IGEPAL CO-630).

29. The polyethylene composition according to claim 1, having an environmental stress crack resistance (ESCR) of more than 500 hours (determined by ASTM D1693 under condition B in 10% IGEPAL CO-630).

30. The polyethylene composition according to claim 1, having an environmental stress crack resistance (ESCR) of more than 1000 hours (determined by ASTM D1693 under condition B in 10% IGEPAL CO-630).

31. The polyethylene composition according to claim 1, having an Izod impact value greater than 9.0 foot-pounds / inch.

32. The polyethylene composition according to claim 1, having an Izod impact value of at least 10.0 foot-pounds / inch.

33. The polyethylene composition according to claim 1, wherein the elastic ratio G' / G'' at 0.5 rad / s is less than 0.

17.

34. The polyethylene composition according to claim 1, wherein the cleavage modulus at 1% is 900 MPa or more.

35. A solution-phase polymerization process for producing polyethylene compositions, The solution-phase polymerization process is A step of polymerizing ethylene and alpha-olefin using a metallocene catalyst in a first reactor, The process involves polymerizing ethylene and alpha-olefin using a Ziegler-Natta catalyst in a second reactor. Includes, The first reactor and the second reactor are configured in series with respect to each other. Polyethylene composition, (i) 0.880-0.930g / cm ３ Density, molecular weight distribution M between 1.7 and 2.7 ｗ / M ｎ , and weight-average molecular weight M of 75,000 to 250,000 g / mol ｗ A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945-0.965g / cm ３ Density, molecular weight distribution M between 2.0 and 3.5 ｗ / M ｎ , and weight-average molecular weight M of 15,000 to 75,000 g / mol ｗ A second ethylene copolymer having 90 to 40 weight percent and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.

0. The polyethylene composition contains 0.942 g / cm³ ３ Densities exceeding 5.0 g / 10 mins, melt index I ２ , melt flow ratio I of 50 or less ２１ / I ２ a solution-phase polymerization process having a long-chain branching coefficient LCBF of 0.0010 or greater.

36. A rotationally molded article prepared from a polyethylene composition, Polyethylene composition, (i) 0.880-0.930g / cm ３ Density, molecular weight distribution M between 1.7 and 2.7 ｗ / M ｎ , and weight-average molecular weight M of 75,000 to 250,000 g / mol ｗ A first ethylene copolymer having 10 to 60 weight percent, (ii) 0.945-0.965g / cm ３ Density, molecular weight distribution M between 2.0 and 3.5 ｗ / M ｎ , and weight-average molecular weight M of 15,000 to 75,000 g / mol ｗ A second ethylene copolymer having 90 to 40 weight percent and Includes, The ratio SCB1 / SCB2 of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer is at least 5.

0. The polyethylene composition contains 0.942 g / cm³ ３ Densities exceeding 5.0 g / 10 mins, melt index I ２ , melt flow ratio I of 50 or less ２１ / I ２ A rotationally molded product having a long-chain branching coefficient LCBF of 0.0010 or more.

37. The rotational molded article according to claim 36, wherein the polyethylene composition contains an additive package comprising at least one additional additive selected from the group consisting of a hindered monophosphite, a diphosphite, a hindered amine light stabilizer, and hindered phenol and hydroxylamine.

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