Polyethylene composition for biaxial orientation

Abstract

The density of the polyethylene composition is from 0.941 to 0.962 g / cm³. 3 Melt index I2 is 0.5 to 5.0 g / 10 min; melt flow ratio I 21 / I2≥40; Z-mean molecular weight distribution Mz / Mw≥2.5; comonomer distribution width index CDBI 50 >50 wt%; and the long-chain branching factor (LCBF) >0.0010. In temperature elution fractionation (CTREF) analysis, the polyethylene composition has more than 70 wt% of material eluted at temperatures greater than 90°C.

Description

Technical Field

[0001] This disclosure relates to polyethylene compositions that can be used to form biaxially oriented films. Background Technology

[0002] Biaxially oriented polyethylene (BOPE) film is produced by stretching a thick precursor (or substrate) film (typically referred to as a cast sheet) in two directions: machine direction (MD) and transverse direction (TD). Stretching can be performed in a single process (simultaneous biaxial stretching) or in two sequential processes (sequential biaxial stretching). The equipment used in the stretching process is commonly referred to as a "stenter" production line.

[0003] Compared to traditional blown films, BOPE films can achieve up to twice the stiffness (tensile modulus), improved tensile strength, impact strength, puncture resistance, flexural crack resistance, and improved (i.e., lower) optical haze.

[0004] BOPE film is suitable for a wide range of packaging applications. The film's excellent properties allow for the design of "all-polyethylene packaging" (as opposed to packaging made with different types of polymers), and this facilitates recycling.

[0005] Tensor lifters are widely used to produce biaxially oriented polypropylene (BOPP) films and biaxially oriented polyethylene terephthalate (BOPET) films. However, polyethylene is relatively difficult to stretch / biaxially oriented, which limits the commercial use of BOPE. Therefore, there is a need for polyethylene compositions that provide "stretchability" in tenter lifter BOPE processes. Summary of the Invention

[0006] We have now developed a polyethylene composition that can be successfully used to prepare BOPE films.

[0007] One embodiment of this disclosure is a polyethylene composition comprising: (i) 5% to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol; and (ii) 95% to 50% by weight of a second ethylene copolymer; wherein the first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer; wherein the ratio (SCB1 / SCB2) of the number of short-chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short-chain branches per thousand carbon atoms in the second ethylene copolymer is 0.8 to 3.5; and wherein the density of the polyethylene composition is 0.941 to 0.962 g / cm³. 3 Melt index I2 is 0.5 to 5.0 g / 10 min; melt flow ratio I 21 / I2≥40; Z-mean molecular weight distribution Mz / Mw≥2.5; comonomer distribution width index CDBI 50 >50wt%; and the long chain branching factor LCBF >0.0010; and wherein, in temperature elution fractionation (CTREF) analysis, the polyethylene composition has more than 70 wt% of material eluted at a temperature greater than 90°C.

[0008] One embodiment of this disclosure is a biaxially oriented polyethylene film comprising a polyethylene composition comprising: (i) 5% to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol; and (ii) 95% to 50% by weight of a second ethylene copolymer; wherein the first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer; wherein the ratio (SCB1 / SCB2) of the number of short-chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short-chain branches per thousand carbon atoms in the second ethylene copolymer is 0.8 to 3.5; and wherein the density of the polyethylene composition is 0.941 to 0.962 g / cm³. 3 Melt index I2 is 0.5 to 5.0 g / 10 min; melt flow ratio I 21 / I2≥40; Z-mean molecular weight distribution Mz / Mw≥2.5; comonomer distribution width index CDBI 50 >50wt%; and the long chain branching factor LCBF >0.0010; and wherein, in temperature elution fractionation (CTREF) analysis, the polyethylene composition has more than 70 wt% of material eluted at a temperature greater than 90°C.

[0009] In one embodiment of this disclosure, the long chain branching factor (LCBF) of the polyethylene composition is greater than 0.0050.

[0010] In one embodiment of this disclosure, the long chain branching factor (LCBF) of the polyethylene composition is greater than 0.0100. Attached Figure Description

[0011] Figure 1 Gel permeation chromatography (GPC-RI) with refractive index detection is shown for a polyethylene composition prepared according to this disclosure and a comparative resin.

[0012] Figure 2 Gel permeation chromatography (GPC-FTIR) with Fourier transform infrared detection is shown for the polyethylene composition prepared according to this disclosure and for comparative resins. The comonomer content (shown as the number of short chain branches per 1000 main chain carbons (y-axis)) is given relative to the copolymer molecular weight (x-axis).

[0013] Figure 3 Temperature elution fractionation (CTREF) characteristic curves of polyethylene compositions prepared according to this disclosure and comparative resins are shown.

[0014] Figure 4 Differential scanning calorimetry (DSC) analysis and characteristic curves of polyethylene compositions prepared according to this disclosure and comparative resins are shown.

[0015] Figure 5 The apparent shear viscosity (Pa·s) relative to the apparent shear rate (s) is shown as obtained by capillary rheology analysis of the polyethylene composition prepared according to this disclosure and a comparative resin. -1 ).

[0016] Figure 6 The stress-strain behavior (in the rubber state) of the polyethylene composition disclosed herein during machine-direction (MD) stretching is shown in... Figure 6 middle.

[0017] Figure 7 The stress-strain behavior (in the rubber state) of the polyethylene composition disclosed herein during machine-direction (TD) stretching is shown in... Figure 7 middle. Detailed Implementation

[0018] As used herein, “about” will be understood by those skilled in the art and will vary to some extent depending on the context in which it is used. If those skilled in the art are unclear about the use of the term when considering the context in which it is used, “about” will mean at most 10% plus or minus a particular term.

[0019] In the context of describing elements (especially in the context of the appended claims), the terms “a,” “an,” and “the,” and similar references, should be interpreted as encompassing both the singular and plural, unless otherwise indicated herein or clearly contradicted by the context. Unless otherwise stated herein, descriptions of numerical ranges are intended only as a shorthand method for individually referring to each individual value falling within the range, and each individual value is incorporated into the specification as if it were individually described herein. All methods described herein may be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by the context. Unless otherwise stated, the use of any and all example or exemplary language (e.g., “such as”) provided herein is intended only to better illustrate the embodiments and not to limit the scope of the claims. No language in this specification should be construed as indicating that any unclaimed element is necessary.

[0020] As used in this article, the term "monomer" refers to a small molecule that can chemically react with itself or other monomers and become chemically bonded to them to form a polymer.

[0021] As used herein, the term "α-olefin" or "alpha-olefin" is used to describe monomers having a straight-chain hydrocarbon chain containing 3 to 20 carbon atoms with a double bond at one end of the chain; the equivalent term is "linear α-olefin". α-olefins may also be referred to as comonomers.

[0022] As used herein, the terms “polyethylene,” “polyethylene composition,” or “ethylene polymer” refer to a macromolecule produced from ethylene monomers and optionally one or more other monomers, regardless of the specific catalyst or method used to prepare the ethylene polymer. In the field of polyethylene, the one or more other monomers are generally referred to as “comonomers” and typically include α-olefins. The term “homogeneous polymer” refers to a polymer containing only one type of monomer. For example, “ethylene homopolymer” is prepared using only ethylene as a polymerizable monomer. The term “copolymer” refers to a polymer containing two or more types of monomers. “Ethylene copolymer” is prepared, for example, using ethylene and one or more other types of polymerizable monomers (e.g., α-olefins). Common types of polyethylene include high-density polyethylene (HDPE); medium-density polyethylene (MDPE); linear low-density polyethylene (LLDPE); and very low-density polyethylene (VLPDE) or ultra-low-density polyethylene (ULPDE), which are also referred to as plastomers and elastomers. The term polyethylene also includes polyethylene terpolymers, which may contain two or more comonomers in addition to ethylene. The term polyethylene also includes combinations or blends of the above-mentioned types of polyethylene.

[0023] In this disclosure, the terms "ethylene homopolymer" or "polyethylene homopolymer" are used to refer to polymers that are products of a polymerization process, wherein only ethylene is intentionally added or intentionally present as a polymerizable monomer.

[0024] In this disclosure, the terms "ethylene copolymer" or "polyethylene copolymer" mean a polymer referred to as the product of a polymerization process, wherein ethylene and one or more α-olefins are intentionally added or intentionally present as polymerizable monomers.

[0025] As used herein, the term "unsubstituted" means that a hydrogen group is bonded to the molecular group following the term "unsubstituted". The term "substituted" means that the group following the term has one or more portions (non-hydrogen groups) that have replaced one or more hydrogen groups at any position within the group.

[0026] The term "membrane" is used herein to refer to a membrane having one or more layers, which is formed by extruding a polymer through one or more die openings. The term "membrane structure" is used to indicate that the membrane has more than one layer (i.e., the membrane structure has at least two layers, at least three layers, etc.).

[0027] In this disclosure, the terms “BOPE membrane” or “BOPE membrane structure” generally describe biaxially oriented membranes or membrane structures in which polyethylene is the main component polymer (i.e., polyethylene is present at a higher weight percentage than other non-polyethylene polymers, based on the total weight of the polymers present in the membrane or membrane structure).

[0028] As used herein, the phrase “all polyethylene” means, when used to describe a membrane or membrane structure, that the membrane or membrane structure will contain at least 90% by weight of a polyethylene composition (as opposed to a non-polyethylene-based polymer material or composition), based on the total weight of the polymer present in the membrane or membrane structure.

[0029] 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. Embodiments of the first ethylene copolymer, the second ethylene copolymer, and the polyethylene composition are described below.

[0030] In one embodiment of this disclosure, the polyethylene composition can be used to manufacture BOPE films or BOPE film structures.

[0031] First ethylene copolymer

[0032] In one embodiment of this disclosure, the first ethylene copolymer comprises both polymerized ethylene and at least one polymerized α-olefin comonomer, wherein the polymerized ethylene is the main substance.

[0033] In embodiments of this disclosure, the α-olefin that can be copolymerized with ethylene to prepare the first ethylene copolymer can be selected from 1-propylene, 1-butene, 1-pentene, 1-hexene and 1-octene and mixtures thereof.

[0034] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a single-point catalyst, non-limiting examples of which include phosphine-imine catalysts, metallocene catalysts, and restricted geometry catalysts, all of which are well known in the art.

[0035] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a single-point polymerization catalyst (“SSC”).

[0036] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a unit point polymerization catalyst in a solution phase polymerization method.

[0037] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a single-point polymerization catalyst having a hafnium (Ha) as the active metal center.

[0038] In one embodiment of this disclosure, the first ethylene copolymer is an ethylene / 1-octene copolymer.

[0039] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a metallocene catalyst.

[0040] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a bridged metallocene catalyst.

[0041] In one embodiment of this disclosure, the first ethylene copolymer is prepared using a bridged metallocene catalyst having formula I:

[0042]

[0043] 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 hydrocarbon group, C 1-20 Alkoxy or C 6-10 Aryl ether group; R2 and R3 are independently selected from hydrogen atoms, C 1-20 hydrocarbon group, C 1-20 Alkoxy or C 6-10 Aryl ether group; R4 and R5 are independently selected from hydrogen atoms and unsubstituted C atoms. 1-20 Hydrocarbon group, substituted C 1-20 hydrocarbon group, C 1-20 Alkoxy or C 6-10 The aromatic ether group; and Q is independently an activatable leaving group ligand.

[0044] In one implementation, G is carbon.

[0045] In one implementation, R4 and R5 are independently aryl groups.

[0046] In one embodiment, R4 and R5 are independently phenyl or substituted phenyl.

[0047] In one embodiment, R4 and R5 are phenyl groups.

[0048] In one embodiment, R4 and R5 are independently substituted phenyl groups.

[0049] In one embodiment, R4 and R5 are substituted phenyl groups, wherein the phenyl groups are substituted with substituted silyl groups.

[0050] In one embodiment, R4 and R5 are substituted phenyl groups, wherein the phenyl groups are substituted with trialkylsilyl groups.

[0051] In one embodiment, R4 and R5 are substituted phenyl groups, wherein the phenyl group is substituted at the para-position with a trialkylsilyl group. In one embodiment, R4 and R5 are substituted phenyl groups, wherein the phenyl group is substituted at the para-position with a trimethylsilyl group. In one embodiment, R4 and R5 are substituted phenyl groups, wherein the phenyl group is substituted at the para-position with a triethylsilyl group.

[0052] In one embodiment, R4 and R5 are independently alkyl groups.

[0053] In one implementation, R4 and R5 are independently alkenyl groups.

[0054] In one implementation, R1 is hydrogen.

[0055] In one embodiment, R1 is an alkyl group.

[0056] In one implementation, R1 is an aryl group.

[0057] In one embodiment, R1 is an alkenyl group.

[0058] In one implementation, R2 and R3 are independently hydrocarbon groups having 1 to 30 carbon atoms.

[0059] In one implementation, R2 and R3 are independently aryl groups.

[0060] In one embodiment, R2 and R3 are independently alkyl groups.

[0061] In one embodiment, R2 and R3 are independently alkyl groups having 1 to 20 carbon atoms.

[0062] In one embodiment, R2 and R3 are independently phenyl or substituted phenyl.

[0063] In one implementation, R2 and R3 are tert-butyl.

[0064] In one implementation, R2 and R3 are hydrogen.

[0065] In one implementation, M is hafnium (Hf).

[0066] In this disclosure, the term "activatable" means that ligand Q can be cleaved from metal center M via a proton-decomposition reaction or extracted from metal center M by a suitable acidic or electrophilic activator compound (also called a "co-catalyst" compound), examples of which are described below. Activatable ligand Q can also be transformed into another ligand cleaved or extracted from metal center M (e.g., a halide can be converted to an alkyl group). Not wishing to be bound by any single theory, the proton-decomposition or extraction reaction produces an active "cationic" metal center that can polymerize olefins.

[0067] In embodiments of this disclosure, the activatable ligand Q is independently selected from hydrogen atoms; halogen atoms; C atoms. 1-20 hydrocarbon group, C 1-20 Alkoxy and C 6-10 Aryl or aryloxy, wherein each of the hydrocarbon, alkoxy, aryl, or aryl ether groups may be unsubstituted or further substituted by one or more halogen or other groups; C 1-8 Alkyl; C 1-8 Alkoxy; C 6-10 Aryl or aryloxy; amide or phosphido radical, but wherein Q is not cyclopentadienyl. Two Q ligands may also bond with each other to form, for example, substituted or unsubstituted diene ligands (e.g., 1,3-butadiene); or groups containing delocalized heteroatoms, such as acetate or acetamiprid groups. In a convenient embodiment of this disclosure, each Q is independently selected from halogen atoms, C... 1-4 Alkyl and benzyl groups. In embodiments of this disclosure, particularly suitable activatable ligand Q is monoanionic, such as a halide ion (e.g., chloride ion) or a hydrocarbon group (e.g., methyl, benzyl).

[0068] In one embodiment of this disclosure, the unit site catalyst for preparing the first ethylene copolymer is hafnium diphenylmethylene (cyclopentadienyl)(2,7-di-tert-butylfluorenyl)dichloride having the following molecular formula:

[0069] [(2,7-tBu2Flu)Ph2C(Cp)HfCl2].

[0070] In one embodiment of this disclosure, the unit site catalyst for preparing the first polyethylene is diphenylmethylene(cyclopentadienyl)(2,7-di-tert-butylfluorenyl)dimethylhafnium having the following molecular formula:

[0071] [(2,7-tBu2Flu)Ph2C(Cp)HfMe2].

[0072] In addition to the single-site catalyst molecule itself, the active single-site catalyst system may also contain one or more of the following: alkylaluminoxane cocatalysts and ion activators. The single-site catalyst system may also optionally contain hindered phenols.

[0073] Although the exact structure of alkylaluminoxanes is uncertain, subject matter experts generally consider them to be oligomers containing repeating units of the following general formula:

[0074] (R)2AlO-(Al(R)-O) n -Al(R)2

[0075] The R group can be the same or different straight-chain, branched or cyclic hydrocarbon group containing 1 to 20 carbon atoms, and n is from 0 to about 50. A non-limiting example of an alkylaluminoxane is methylaluminoxane (or MAO), wherein each R group is methyl.

[0076] In one embodiment of this disclosure, R of the alkylaluminoxane is methyl, and m is 10 to 40.

[0077] In one embodiment of this disclosure, the cocatalyst is modified methylaluminoxane (MMAO).

[0078] It is well known in the art that alkylaluminoxanes can act as both alkylating agents and activators. Therefore, alkylaluminoxane cocatalysts are often used in combination with activatable ligands (such as halogens).

[0079] Typically, ion activators consist of a cation and a bulky anion; the latter is essentially uncoordinated. A non-limiting example of an ion activator is a boron ion activator, which is a tetracoordinate with four ligands bonded to the boron atom. Non-limiting examples of boron ion activators include those shown below:

[0080] [R 5 ] + [B(R 7 )4] -

[0081] Where B represents a boron atom, R 5 It is an aromatic hydrocarbon group (e.g., a triphenylmethyl cation), and each R 7 Independently selected from unsubstituted or 3 to 5 atoms selected from fluorine atoms, C 1-4 A phenyl group substituted with an alkyl or alkoxy group, wherein the C 1-4 Alkyl or alkoxy groups are either unsubstituted or substituted with fluorine atoms; and -Si(R 9 )3 silyl groups, wherein each R 9 Independently selected from hydrogen atoms and C atoms 1-4 Alkyl groups; and

[0082] [(R 8 ) t ZH] + [B(R 7 )4] -

[0083] Where B is a boron atom, H is a hydrogen atom, Z is a nitrogen or phosphorus atom, t is 2 or 3, and R 8 Selected from C 1-8 Alkyl, unsubstituted or with at most three carbons 1-4 Alkyl-substituted phenyl, or an R 8 Together with a nitrogen atom, it can form a phenylamine group, and R 7 As defined above.

[0084] In both formulas, R 7Non-limiting examples are pentafluorophenyl. Generally, boron ion activators can be described as salts of tetra(perfluorophenyl)boron; non-limiting examples include phenylammonium salts, carbium salts, oxonium salts, phosphonium salts, and sulfonium salts of tetra(perfluorophenyl)boron with phenylammonium and triphenylmethyl (or triphenylmethylonium). Further non-limiting examples of ion activators 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-dimethylbenzene Ammonium tetra(phenyl)boron; N,N-diethylphenylammonium tetra(phenyl)boron; N,N-diethylphenylammonium tetra(phenyl)n-butylboron; N,N-2,4,6-pentamethylphenylammonium 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; tropillium tetrakispentafluorophenyl (borate); Triphenylmethylonium tetra(pentafluorophenyl)borate; Benzene(diazo)tetra(pentafluorophenyl)borate; Tetra(2,3,5,6-tetrafluorophenyl)borate; Triphenylmethylonium tetra(2,3,5,6-tetrafluorophenyl)borate; Benzene(diazo)tetra(3,4,5-trifluorophenyl)borate; Tetra(3,4,5-trifluorophenyl)borate; Benzene(diazo)tetra(3,4,5-trifluorophenyl)borate Ontium tetra(1,2,2-trifluorovinyl)borate; triphenylmethylonium tetra(1,2,2-trifluorovinyl)borate; benzene(diazo)tetra(1,2,2-trifluorovinyl)borate; tetra(2,3,4,5-tetrafluorophenyl)borate; triphenylmethylonium tetra(2,3,4,5-tetrafluorophenyl)borate; and benzene(diazo)tetra(2,3,4,5-tetrafluorophenyl)borate. Commercially available ionic activators include N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate and triphenylmethylonium tetra(pentafluorophenyl)borate.

[0085] Non-limiting examples of hindered phenols include butylated phenolic 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.

[0086] To produce an active single-point catalyst system, the amounts and molar ratios of the following three or four components are optimized: single-point catalyst molecules (e.g., metallocene), alkylaluminoxanes, ion activators, and optionally hindered phenols.

[0087] In one embodiment of this disclosure, the unit-point catalyst used to prepare the first ethylene copolymer generates long-chain branches, and the first ethylene copolymer will contain long-chain branches, hereinafter referred to as 'LCB'.

[0088] LCB is a well-known structural phenomenon in ethylene copolymers and is familiar to those skilled in the art. Traditionally, three methods exist for LCB analysis: nuclear magnetic resonance spectroscopy (NMR), e.g., see J. C. Landall, J. Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, 29, 201; triple-detection SEC equipped with a DRI, viscometer, and low-angle laser scattering detector, e.g., see W. Yau and D. D. Hill, Int. J. Polym. Anal. Character. 1996; 2:151; and rheology, e.g., see W. Graessley, Acc. Chem. Res. 1977, 10, 332-339. In embodiments of this disclosure, the long-chain branches are essentially macromolecular, i.e. long enough to be observed in NMR spectroscopy, triple-detector SEC experiments, or rheological experiments.

[0089] In one embodiment of this disclosure, the first ethylene copolymer contains long-chain branches characterized by the long-chain branching factor (LCBF) disclosed herein. In embodiments of this disclosure, the upper limit of the LCBF of the first ethylene copolymer may be 0.5000, or 0.4000, or 0.3000 (dimensionless). In embodiments of this disclosure, the lower limit of the LCBF of the first ethylene copolymer may be 0.0010, or 0.0015, or 0.0020, or 0.0100, or 0.0500, or 0.1000 (dimensionless).

[0090] The first ethylene copolymer may contain catalyst residues that reflect the chemical composition of the catalyst formulation used to prepare the catalyst. Those skilled in the art will understand that catalyst residues are typically quantified by, for example, the parts per million (ppm) of metals in the first ethylene copolymer (or polyethylene composition; see below), wherein the metals present originate from metals in the catalyst formulation used to prepare the catalyst. Non-limiting examples of metal residues that may be present include Group 4 metals, titanium, zirconium, and hafnium. In embodiments of this disclosure, the upper limit of the ppm of metals in the first ethylene copolymer may be about 3.0 ppm, in other cases about 2.0 ppm, and in still other cases about 1.5 ppm. In embodiments of this disclosure, the lower limit of the ppm of metals in the first ethylene copolymer may be about 0.03 ppm, in other cases about 0.09 ppm, and in still other cases about 0.15 ppm.

[0091] The short-chain branches in the first ethylene copolymer (i.e., short-chain branches / thousand main chain carbon atoms, SCB1 or SCB1 / 1000C) are branches formed due to the presence of α-olefin comonomers in the first ethylene copolymer, and for example, for 1-butene comonomers, they will have two carbon atoms, or for 1-hexene comonomers, they will have four carbon atoms, or for 1-octene comonomers, they will have six carbon atoms, and so on.

[0092] In one embodiment of this disclosure, the first ethylene copolymer has 1 to 50 short chain branches per thousand carbon atoms (SCB1). In a further embodiment, the first ethylene copolymer has 1 to 25 short chain branches per thousand carbon atoms (SCB1), or 1 to 15 short chain branches per thousand carbon atoms (SCB1), or 1 to 10 short chain branches per thousand carbon atoms (SCB1).

[0093] In one embodiment of this disclosure, the number of short chain branches per thousand carbon atoms (SCB1) in the first ethylene copolymer is greater than the number of short chain branches per thousand carbon atoms (SCB2) in the second ethylene copolymer.

[0094] In one embodiment of this disclosure, the first ethylene copolymer has 0.5 to 25.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 0.5 to 20.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 0.5 to 15.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 0.5 to 10.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 0.5 to 7.5 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 0.5 to 5.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 25 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 20.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 15.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 10.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 7.5 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 5.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.5 to 25 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.5 to 20.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 1.5 to 15.0 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 1.5 to 10.0 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 1.5 to 7.5 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 1.5 to 5.0 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 2.0 to 25 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 2.0 to 20.0 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 2.0 to 15.0 short chain branches per thousand carbon atoms (SCB1).In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 10.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 7.5 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 5.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.3 to 25.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.3 to 20.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.3 to 15.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.3 to 10.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has 2.3 to 7.5 short chain branches per thousand carbon atoms (SCB1). In another embodiment of this disclosure, the first ethylene copolymer has 2.3 to 5.0 short chain branches per thousand carbon atoms (SCB1).

[0095] In one embodiment of this disclosure, the first ethylene copolymer has less than (<) 10 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has less than (<) 7.5 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has less than (<) 5.0 short chain branches per thousand carbon atoms (SCB1). In one embodiment of this disclosure, the first ethylene copolymer has less than (<) 4.0 short chain branches per thousand carbon atoms (SCB1).

[0096] In one embodiment of this disclosure, the density of the first copolymer is less than the density of the second ethylene copolymer.

[0097] In one embodiment of this disclosure, the density of the first ethylene copolymer is from 0.910 to 0.975 g / cm³. 3 This includes any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of this disclosure, the density of the first ethylene copolymer is from 0.930 to 0.970 g / cm³. 3 Or 0.930 to 0.965 g / cm³ 3 Or 0.930 to 0.960 g / cm³ 3 Or 0.935 to 0.965 g / cm³ 3 Or 0.935 to 0.960 g / cm³ 3 Or 0.935 to 0.955 g / cm³3 Or 0.935 to 0.950 g / cm³ 3 Or 0.930 to 0.950 g / cm³ 3 or 0.930 to 0.955 g / cm³ 3 In other embodiments of this disclosure, the density of the first ethylene copolymer is from 0.915 to 0.945 g / cm³. 3 Or 0.915 to 0.940 g / cm³ 3 Or 0.915 to 0.935 g / cm³ 3 Or 0.915 to 0.930 g / cm³ 3 Or 0.920 to 0.930 g / cm³ 3 .

[0098] In the embodiments of this disclosure, the melt index I2 of the first ethylene copolymer is ≤5.0 g / 10 min, or <5.0 g / 10 min, or ≤2.5 g / 10 min, or <2.5 g / 10 min, or ≤1.0 g / 10 min, or <1.0 g / 10 min, or ≤0.5 g / 10 min, or <0.5 g / 10 min, or ≤0.4 g / 10 min, or <0.4 g / 10 min, or ≤0.2 g / 10 min, or <0.2 g / 10 min.

[0099] In embodiments of this disclosure, the melt index I2 of the first ethylene copolymer is from 0.001 to 5.0 g / 10 min, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the melt index I2 of the first ethylene copolymer may be from 0.01 to 5.0 g / 10 min, or from 0.01 to 2.5 g / 10 min, or from 0.01 to 2.0 g / 10 min, or from 0.01 to 1.5 g / 10 min, or from 0.01 to 1.0 g / 10 min, or from 0.01 to 0.5 g / 10 min, or from 0.01 to 0.4 g / 10 min, or from 0.01 to 0.2 g / 10 min.

[0100] In one embodiment of this disclosure, the melt index I2 of the first ethylene copolymer is less than the melt index I2 of the second ethylene copolymer.

[0101] In embodiments of this disclosure, the weight-average molecular weight M of the first ethylene copolymer w Greater than 170,000 g / mol, or greater than 175,000 g / mol, or greater than 200,000 g / mol.

[0102] In embodiments of this disclosure, the weight-average molecular weight M of the first ethylene copolymer wThe weight-average molecular weight M of the first ethylene copolymer is 150,000 to 500,000 g / mol, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the weight-average molecular weight M of the first ethylene copolymer is... w The weight-average molecular weight M of the first ethylene copolymer is 175,000 to 475,000 g / mol, or 180,000 to 470,000 g / mol, or 175,000 to 400,000 g / mol, or 175,000 to 350,000 g / mol, or 200,000 to 475,000 g / mol, or 200,000 to 400,000 g / mol, or 200,000 to 350,000 g / mol, or 200,000 to 325,000 g / mol. In other embodiments of this disclosure, the weight-average molecular weight M of the first ethylene copolymer is... w The values ​​are 170,000 to 475,000 g / mol, or 170,000 to 470,000 g / mol, or 170,000 to 400,000 g / mol, or 170,000 to 350,000 g / mol, or 175,000 to 475,000 g / mol, or 175,000 to 400,000 g / mol, or 160,000 to 350,000 g / mol, or 160,000 to 325,000 g / mol.

[0103] In one embodiment of this disclosure, the weight-average molecular weight Mw of the first ethylene copolymer is greater than the weight-average molecular weight Mw of the second ethylene copolymer.

[0104] In one embodiment of this disclosure, the melt flow ratio of the first ethylene copolymer is I 21 / I2 is less than 25, or less than 23, or less than 20.

[0105] In embodiments of this disclosure, the molecular weight distribution M of the first ethylene copolymer w / M n The upper limit can be about 2.7, or about 2.5, or about 2.4, or about 2.3, or about 2.2. In embodiments of this disclosure, the molecular weight distribution M of the first ethylene copolymer is... w / M n The lower limit could be approximately 1.6, or approximately 1.7, or approximately 1.8, or approximately 1.9.

[0106] In embodiments of this disclosure, the molecular weight distribution M of the first ethylene copolymer w / M nThe molecular weight is ≤3.0, or <3.0, or ≤2.7, or <2.7, or ≤2.5, or <2.5, or ≤2.3, or <2.3, or ≤2.1, or <2.1, or about 2. In another embodiment of this disclosure, the molecular weight distribution M of the first ethylene copolymer is... w / M n The value is 1.7 to 3.0, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the molecular weight distribution M of the first ethylene copolymer is... w / M n It is 1.7 to 2.7, or 1.8 to 2.7, or 1.8 to 2.5, or 1.8 to 2.3, or 1.9 to 2.1, or about 2.0.

[0107] In one embodiment of this disclosure, CDBI is obtained during solution-phase polymerization in a single reactor during the preparation of the first ethylene copolymer. 50 The unit site catalyst is 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 ethylene copolymer.

[0108] In embodiments of this 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 ethylene copolymer and the second ethylene copolymer) can be from about 5 wt% to about 60 wt%, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the weight percentage (wt%) of the first ethylene copolymer in the polyethylene copolymer composition can be from about 5 wt% to about 50 wt%, or from about 10 wt% to about 40 wt%, or from about 15 wt% to about 40 wt%, or from about 15 wt% to about 35 wt%, or from about 10 wt% to about 35 wt%, or from 20 wt% to 50 wt%, or from 20 wt% to 40 wt%, or from 25 wt% to 50 wt%.

[0109] Second ethylene copolymer

[0110] In one embodiment of this disclosure, the second ethylene copolymer comprises both polymerized ethylene and at least one polymerized α-olefin comonomer, wherein the polymerized ethylene is the main substance.

[0111] In embodiments of this disclosure, the α-olefin that can be copolymerized with ethylene to prepare a second ethylene copolymer can be selected from 1-propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and mixtures thereof.

[0112] In one embodiment of this 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.

[0113] In one embodiment of this disclosure, the second ethylene copolymer is prepared using a Ziegler-Natta catalyst system.

[0114] In one embodiment of this disclosure, the second ethylene copolymer is prepared using a Ziegler-Natta catalyst system in a solution-phase polymerization method.

[0115] Ziegler-Natta catalyst systems are well known to those skilled in the art. Ziegler-Natta catalysts can be in-line or batch-process Ziegler-Natta catalyst systems. The term "in-line Ziegler-Natta catalyst system" refers to the continuous synthesis of a small amount of active Ziegler-Natta catalyst system and the immediate injection of said catalyst into at least one continuously operating reactor, wherein said catalyst polymerizes ethylene and one or more optional α-olefins to form an ethylene polymer. The term "batch-process Ziegler-Natta catalyst system" or "batch-process Ziegler-Natta pre-catalyst" refers to the synthesis of a much larger quantity of catalyst or pre-catalyst in one or more mixing vessels outside of or separate from a continuously operating solution polymerization process. Once prepared, the batch-process Ziegler-Natta catalyst system or batch-process Ziegler-Natta pre-catalyst is transferred to a catalyst storage tank. The term "pre-catalyst" refers to an inert catalyst system (inert for ethylene polymerization); the pre-catalyst is converted into an active catalyst by adding an alkylaluminum co-catalyst. As needed, the pre-catalyst is pumped from a storage tank to at least one continuously operating reactor, where the active catalyst polymerizes ethylene and one or more optional α-olefins to form an ethylene copolymer. The pre-catalyst can be converted into the active catalyst either in the reactor or outside the reactor or along the path to the reactor.

[0116] A variety of compounds can be used to synthesize active Ziegler-Natta catalyst systems. Various compounds that can be combined to produce active Ziegler-Natta catalyst systems are described below. Those skilled in the art will understand that the embodiments described in this disclosure are not limited to the specific compounds disclosed.

[0117] The active Ziegler-Natta catalyst system can be formed from magnesium compounds, chlorides, metal compounds, alkylaluminum co-catalysts, and alkylaluminum. As those skilled in the art will appreciate, the Ziegler-Natta catalyst system may contain additional components; non-limiting examples of additional components are electron donors, such as amines or ethers.

[0118] Non-limiting examples of in-line (or batch) Ziegler-Natta catalyst systems can be prepared as follows. In a first step, a solution of a magnesium compound is reacted with a solution of a chloride to form a magnesium chloride support suspended in solution. Non-limiting examples of magnesium compounds include Mg(R) 1 )2; where R 1 The group can be the same or different straight-chain, branched, or cyclic hydrocarbon group containing 1 to 10 carbon atoms. Non-limiting examples of chlorides include R... 2 Cl; where R 2 A straight-chain, branched, or cyclic hydrocarbon group representing a hydrogen atom or containing 1 to 10 carbon atoms. In the first step, the solution of the magnesium compound may also contain an alkylaluminum compound. Non-limiting examples of alkylaluminum compounds include Al(R) 3 )3, where R 3 The functional group can be the same or different straight-chain, branched, or cyclic hydrocarbon group containing 1 to 10 carbon atoms. In the second step, a solution of the metal compound is added to the magnesium chloride solution, thereby loading the metal compound onto the magnesium chloride. Non-limiting examples of suitable metal compounds include M(X). n orMO(X) n ; where M represents a metal selected from Groups 4 to 8 of the periodic table, or a mixture of metals selected from Groups 4 to 8; O represents oxygen; X represents chlorine or bromine; and n is an integer from 3 to 6 that satisfies the oxidation state of the metal. Further non-limiting examples of suitable metal compounds include Group 4 to 8 metal alkyl groups, metal alkoxides (which can be prepared by reacting a metal alkyl group with an alcohol), and mixed ligand metal compounds containing a mixture of halide, alkyl, and alkoxide ligands. In one embodiment of this disclosure, a suitable metal compound is titanium tetrachloride (TiCl4). In the third step, a solution of an alkylaluminum co-catalyst is added to the metal compound supported on magnesium chloride. Various alkylaluminum co-catalysts are suitable, as represented by the following formula: Al(R 4 ) p (OR 9 ) q (X) r

[0119] Where R 4 The group can be the same or different hydrocarbon groups having 1 to 10 carbon atoms; OR 9 The groups can be the same or different alkoxy or aryloxy groups, where R 9It is a hydrocarbon group with 1 to 10 carbon atoms bonded to oxygen; X is chlorine or bromine; and (p+q+r) = 3, provided that p is greater than 0. Non-limiting examples of commonly used alkylaluminum cocatalysts include trimethylaluminum, triethylaluminum, tributylaluminum, dimethylmethoxide aluminum, diethylethoxide aluminum, dibutylbutoxide aluminum, dimethylaluminum chloride or dimethylaluminum bromide, diethylaluminum chloride or diethylaluminum bromide, dibutylaluminum chloride or dibutylaluminum bromide, and ethylaluminum dichloride or ethylaluminum dibromide.

[0120] The methods described above for synthesizing active online (or batch) Ziegler-Natta catalyst systems can be carried out in a variety of solvents; non-limiting examples of solvents include straight-chain or branched C5 to C6 catalysts. 12 Alkanes or mixtures thereof.

[0121] The second ethylene copolymer may contain catalyst residues that reflect the chemical composition of the catalyst formulation used to prepare the catalyst. Those skilled in the art will understand that catalyst residues are typically quantified by, for example, the parts per million (ppm) of metals in the second ethylene copolymer (or polyethylene composition; see below), wherein the metals present originate from metals in the catalyst formulation used to prepare the catalyst. Non-limiting examples of metal residues that may be present include Group 4 metals, titanium, zirconium, and hafnium. In embodiments of this disclosure, the upper limit of the ppm of metals in the second ethylene copolymer may be about 3.0 ppm, in other cases about 2.0 ppm, and in still other cases about 1.5 ppm. In embodiments of this disclosure, the lower limit of the ppm of metals in the second ethylene copolymer may be about 0.03 ppm, in other cases about 0.09 ppm, and in still other cases about 0.15 ppm.

[0122] The short-chain branches in the second ethylene copolymer (i.e., short-chain branches / 1000 main chain carbon atoms, SCB2 or SCB2 / 1000C) are branches formed due to the presence of α-olefin comonomers in the second ethylene copolymer, and for example, they will have two carbon atoms for 1-butene comonomers, or four carbon atoms for 1-hexene comonomers, or six carbon atoms for 1-octene comonomers, and so on.

[0123] In one embodiment of this disclosure, the number of short chain branches per thousand carbon atoms (SCB2) in the second ethylene copolymer is less than the number of short chain branches per thousand carbon atoms (SCB1) in the first ethylene copolymer.

[0124] In one embodiment of this disclosure, the second ethylene copolymer has 0.5 to 15.0 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has 0.5 to 10.0 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has 0.5 to 5.0 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has 0.5 to 2.5 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has 0.5 to 2.2 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has 1.0 to 15.0 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has 1.0 to 10.0 short chain branches per thousand carbon atoms (SCB2). In one embodiment of this disclosure, the second ethylene copolymer has 1.0 to 5.0 short chain branches per thousand carbon atoms (SCB2). In one embodiment of this disclosure, the second ethylene copolymer has 1.0 to 2.5 short chain branches per thousand carbon atoms (SCB2). In one embodiment of this disclosure, the second ethylene copolymer has 1.0 to 2.2 short chain branches per thousand carbon atoms (SCB2).

[0125] In one embodiment of this disclosure, the second ethylene copolymer has less than (<) 5.0 short chain branches per thousand carbon atoms (SCB2). In another embodiment of this disclosure, the second ethylene copolymer has less than (<) 3.0 short chain branches per thousand carbon atoms (SCB2).

[0126] In one embodiment of this disclosure, the density of the second copolymer is greater than the density of the first ethylene copolymer.

[0127] In one embodiment of this disclosure, the density of the second ethylene copolymer is from 0.920 to 0.975 g / cm³. 3 This includes any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of this disclosure, the density of the second ethylene copolymer is from 0.940 to 0.970 g / cm³. 3 Or 0.940 to 0.965 g / cm³ 3 Or 0.940 to 0.960 g / cm³ 3 Or 0.942 to 0.967 g / cm³ 3 Or 0.942 to 0.965 g / cm³ 3 Or 0.942 to 0.960 g / cm³ 3 Or 0.940 to 0.955 g / cm³ 3Or 0.935 to 0.960 g / cm³ 3 Or 0.935 to 0.955 g / cm³ 3 Or 0.942 to 0.955 g / cm³ 3 Or 0.945 to 0.955 g / cm³ 3 In other embodiments of this disclosure, the density of the second ethylene copolymer is from 0.920 to 0.960 g / cm³. 3 Or 0.920 to 0.955 g / cm³ 3 Or 0.920 to 0.950 g / cm³ 3 Or 0.920 to 0.945 g / cm³ 3 Or 0.920 to 0.940 g / cm³ 3 .

[0128] In the embodiments of this disclosure, the melt index I2 of the second ethylene copolymer is ≥10.0 g / 10 min, or >10.0 g / 10 min, or ≥20.0 g / 10 min, or >20 g / 10 min, or ≥25.0 g / 10 min, or >25 g / 10 min.

[0129] In embodiments of this disclosure, the melt index I2 of the second ethylene copolymer is from 10 to 1,000, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the melt index I2 of the second ethylene copolymer is 10 to 500 g / 10 min, or 10 to 250 g / 10 min, or 10 to 150 g / 10 min, or 20 to 500 g / 10 min, or 20 to 250 g / 10 min, or 20 to 150 g / 10 min, or 10 to 100 g / 10 min, or 20 to 100 g / 10 min, or 10 to 75 g / 10 min, or 20 to 75 g / 10 min.

[0130] 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.

[0131] In one embodiment of this disclosure, the weight-average molecular weight M of the second ethylene copolymer w ≤75,000 g / mol, or ≤60,000 g / mol, or ≤50,000 g / mol, or ≤45,000 g / mol. In another embodiment, the weight-average molecular weight M of the second ethylene copolymer is... w The weight-average molecular weight M of the second ethylene copolymer is 5,000 to 75,000 g / mol, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the weight-average molecular weight M of the second ethylene copolymer is... wThe values ​​are 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 30,000 to 55,000 g / mol, or 30,000 to 50,000 g / mol, or 30,000 to 45,000 g / mol.

[0132] In one embodiment of this disclosure, the weight-average molecular weight Mw of the second ethylene copolymer is lower than that of the first ethylene copolymer.

[0133] In embodiments of this disclosure, the molecular weight distribution M of the second ethylene copolymer w / M n The molecular weight distribution M of the second ethylene copolymer is ≥2.3, or >2.3, or ≥2.5, or >2.5, or ≥2.7, or >2.7, or ≥2.9, or >2.9, or ≥3.0, or 3.0. In embodiments of this disclosure, the molecular weight distribution M of the second ethylene copolymer is... w / M n The values ​​are 2.3 to 6.0, or 2.3 to 5.5, or 2.3 to 5.0, or 2.3 to 4.5, or 2.3 to 4.0, or 2.3 to 3.5, or 2.3 to 3.0, or 2.5 to 5.0, or 2.5 to 4.5, or 2.5 to 4.0, or 2.5 to 3.5, or 2.7 to 5.0, or 2.7 to 4.5, or 2.7 to 4.0, or 2.7 to 3.5.

[0134] In one embodiment of this disclosure, CDBI is obtained during solution-phase polymerization in a single reactor during the preparation of the second ethylene copolymer. 50 Multisite catalysts of ethylene copolymers of less than 60% by weight or less than 50% by weight.

[0135] In embodiments of this 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) can be from about 95 wt% to about 40 wt%, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the weight percentage (wt%) of the second ethylene copolymer in the polyethylene copolymer composition can be from about 95 wt% to about 50 wt%, or from about 90 wt% to about 40 wt%, or from about 85 wt% to about 50 wt%, or from about 90 wt% to about 60 wt%, or from about 85 wt% to about 60 wt%, or from about 85 wt% to about 65 wt%, or from 75 wt% to 50 wt%.

[0136] Polyethylene composition

[0137] In one embodiment of this disclosure, the polyethylene composition will comprise a first ethylene copolymer and a second ethylene copolymer (each as defined above).

[0138] The polyethylene compositions disclosed herein can be prepared using any techniques well known in the art, including but not limited to melt blending, solution blending, or in-reactor blending to mix a first ethylene copolymer and a second ethylene copolymer together.

[0139] In one embodiment, the polyethylene composition of this disclosure is prepared as follows: a first ethylene copolymer is obtained using a single-site catalyst in a first reactor, and a second ethylene copolymer is obtained using a multi-site catalyst in a second reactor.

[0140] In one embodiment, the polyethylene composition of this disclosure is prepared by: polymerizing ethylene and α-olefins in a first reactor using a single-site catalyst to form a first ethylene copolymer; and polymerizing ethylene and α-olefins in a second reactor using a multi-site catalyst to form a second ethylene copolymer.

[0141] In one embodiment, the polyethylene composition of this disclosure is prepared by: polymerizing ethylene and α-olefins in a first solution-phase polymerization reactor using a single-site catalyst to form a first ethylene copolymer; and polymerizing ethylene and α-olefins in a second solution-phase polymerization reactor using a multi-site catalyst to form a second ethylene copolymer.

[0142] In one embodiment, the polyethylene composition of this disclosure is prepared by: polymerizing ethylene and α-olefins in a first solution-phase polymerization reactor using a single-site catalyst to form a first ethylene copolymer; and polymerizing ethylene and α-olefins in a second solution-phase polymerization reactor using a multi-site catalyst to form a second ethylene copolymer, wherein the first and second solution-phase polymerization reactors are configured in series with each other.

[0143] In one embodiment, the polyethylene composition of this disclosure is prepared by: polymerizing ethylene and α-olefins in a first solution-phase polymerization reactor using a single-site catalyst to form a first ethylene copolymer; and polymerizing ethylene and α-olefins in a second solution-phase polymerization reactor using a multi-site catalyst to form a second ethylene copolymer, wherein the first and second solution-phase polymerization reactors are configured in parallel with each other.

[0144] In the implementation scheme, the solution-phase polymerization reactor used as the first solution-phase reactor is a continuous stirred tank reactor or a tubular reactor.

[0145] 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.

[0146] In solution-phase polymerization, the monomer is dissolved / dispersed in a solvent and then fed into the reactor (or, for gaseous monomers, the monomer can be fed into the reactor so that it dissolves in the reaction mixture). Prior to mixing, the solvent and monomer are typically purified to remove potential catalyst poisons, such as water, oxygen, or metallic impurities. Feedstock purification follows standard practices in the art, such as the use of molecular sieves, alumina beds, and oxygen-scavenging catalysts for monomer purification. The solvent itself (e.g., methylpentane, cyclohexane, hexane, or toluene) is also preferably treated in a similar manner.

[0147] The raw materials can be heated or cooled before being fed into the reactor.

[0148] Typically, catalyst components can be premixed in the solvent used for the reaction or fed into the reactor as a separate stream. In some cases, premixing of the catalyst components may be necessary to provide them with reaction time before they enter the polymerization reaction zone. This "on-line mixing" technique is well known to those skilled in the art.

[0149] Solution polymerization methods for ethylene polymerization or copolymerization are well known in the art (see, for example, U.S. Patent Nos. 6,372,864 and 6,777,509). These methods are carried out in the presence of an inert hydrocarbon solvent. A variety of solvents can be used as process solvents in the solution-phase polymerization reactor; non-limiting examples include linear, branched, or cyclic C5 to C64 solvents. 12Alkanes. Suitable catalyst component solvents include aliphatic and aromatic hydrocarbons. Non-limiting examples of aliphatic catalyst component solvents include straight-chain, branched, or cyclic C4 hydrocarbons. 5-12 Aliphatic hydrocarbons, such as pentane, methylpentane, hexane, heptane, octane, cyclohexane, cyclopentane, methylcyclohexane, hydrogenated naphtha, or combinations thereof. Non-limiting examples of solvents for aromatic catalyst components include benzene, toluene (methylbenzene), ethylbenzene, o-xylene (1,2-dimethylbenzene), m-xylene (1,3-dimethylbenzene), p-xylene (1,4-dimethylbenzene), mixtures of xylene isomers, trimethylbenzene (1,2,3-trimethylbenzene), pseudotrimethylbenzene (1,2,4-trimethylbenzene), mesitylene (1,3,5-trimethylbenzene), mixtures of trimethylbenzene isomers, tetramethylbenzene (1,2,3,4-tetramethylbenzene), mesitylene (1,2,3,5-tetramethylbenzene), mixtures of tetramethylbenzene isomers, pentamethylbenzene, hexamethylbenzene, and combinations thereof.

[0150] In embodiments of this disclosure, the polymerization temperature in conventional solution methods can be from about 80°C to about 300°C. In one embodiment of this disclosure, the polymerization temperature in the solution method is from about 120°C to about 250°C.

[0151] In embodiments of this disclosure, the polymerization pressure in the solution process can be a "medium-pressure process," meaning the pressure in the reactor is less than about 6,000 psi (about 42,000 kPa). In embodiments of this disclosure, the polymerization pressure in the solution process can 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).

[0152] In embodiments of this disclosure, suitable comonomers (i.e., α-olefins) for copolymerization with ethylene in a solution-phase polymerization method include C 3-20 Monoolefins and dienes. In embodiments of this disclosure, comonomers that can be copolymerized with ethylene include C 3-12 α-olefins, which are unsubstituted or have at most two carbon atoms 1-6 Alkyl substitution, C 8-12 Vinyl aromatic monomers, which are unsubstituted or composed of at most two selected from C 1-4 Alkyl substituent substitution, C 4-12 Straight-chain or cyclic dienes that are unsubstituted or C-shaped 1-4Alkyl substitution. In other embodiments of this disclosure, the α-olefin that can be copolymerized with ethylene is one or more of the following: propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene, styrene, α-methylstyrene and restricted cyclic olefins, such as cyclobutene, cyclopentene, dicyclopentadiene norbornene, alkyl-substituted norbornene, alkenyl-substituted norbornene, etc. (e.g., 5-methylene-2-norbornene and 5-ethylidene-2-norbornene, bicyclo-(2,2,1)-hept-2,5-diene).

[0153] In one embodiment of this disclosure, the polyethylene composition comprises ethylene and one or more α-olefins selected from 1-butene, 1-hexene, 1-octene, and mixtures thereof.

[0154] In one embodiment of this disclosure, the polyethylene composition comprises ethylene and one or more α-olefins selected from 1-hexene, 1-octene, and mixtures thereof.

[0155] In one embodiment of this disclosure, the polyethylene composition comprises ethylene and 1-octene.

[0156] In embodiments of this disclosure, the polyethylene composition has 0.01 mol% to 5 mol% of one or more α-olefins, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the polyethylene composition has 0.05 mol% to 5.0 mol% of one or more α-olefins, or 0.05 mol% to 2.5 mol% of one or more α-olefins, or 0.05 mol% to 1.5 mol% of one or more α-olefins, or 0.05 mol% to 1.0 mol% of one or more α-olefins, or 0.1 mol% to 2.5 mol% of one or more α-olefins, or 0.1 mol% to 1.5 mol% of one or more α-olefins, or 0.1 mol% to 1.0 mol% of one or more α-olefins.

[0157] In embodiments of this disclosure, the polyethylene composition has 0.05 mol% to 5.0 mol% of 1-octene, or 0.05 mol% to 2.5 mol% of 1-octene, or 0.05 mol% to 1.5 mol% of 1-octene, or 0.05 mol% to 1.0 mol% of 1-octene, or 0.1 mol% to 2.5 mol% of 1-octene, or 0.1 mol% to 1.5 mol% of 1-octene, or 0.10 mol% to 1.0 mol% of 1-octene.

[0158] In embodiments of this disclosure, the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (i.e., SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (i.e., SCB2) in the second ethylene copolymer is less than 5.0, or less than 4.0, or less than 3.0, or less than 2.5, or less than 2.0.

[0159] In embodiments of this disclosure, the ratio (SCB1 / SCB2) of the number of short-chain branches per thousand carbon atoms in the first ethylene copolymer (i.e., SCB1) to the number of short-chain branches per thousand carbon atoms in the second ethylene copolymer (i.e., SCB2) of the polyethylene composition comprising the first ethylene copolymer and the second ethylene copolymer (as defined above) will be 0.8 to 5.0, or 0.8 to 3.5, or 0.8 to 3.0, or 1.0 to 5.0, or 1.0 to 4.0, or 1.0 to 3.5, or 1.0 to 3.0, or 1.0 to 2.8, or 1.0 to 2.5, or 1.0 to 2.0, or 1.0 to 1.5, or 0.8 to 2.8, or 0.8 to 2.5, or 0.8 to 2.0, or 0.8 to 1.5, or greater than 1.0 to 5.0, or greater than 1.0 to 4.0, or greater than 1.0 to 3.5, or greater than 1.0 to 3.0, or greater than 1.0 to 2.8, or greater than 1.0 to 2.5.

[0160] In embodiments of this disclosure, the weight-average molecular weight M of the polyethylene composition is... w The weight-average molecular weight M of the polyethylene composition is 65,000 to 250,000 g / mol, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the weight-average molecular weight M of the polyethylene composition is... W The values ​​are 75,000 to 200,000 g / mol, or 65,000 to 175,000 g / mol, or 75,000 to 150,000 g / mol, or 65,000 to 150,000 g / mol, or 75,000 to 125,000 g / mol, or 65,000 to 125,000 g / mol, or 85,000 to 125,000 g / mol, or 90,000 to 125,000 g / mol.

[0161] In one embodiment of this disclosure, the number-average molecular weight M of the polyethylene composition is... n≤60,000 g / mol, or ≤50,000 g / mol, or <50,000 g / mol, or ≤45,000 g / mol, or <45,000 g / mol, or ≤40,000 g / mol, or <40,000 g / mol, or ≤35,000 g / mol, or <35,000 g / mol, or ≤30,000 g / mol, or <30,000 g / mol, or ≤25,000 g / mol, or <25,000 g / mol. In another embodiment of this disclosure, the number-average molecular weight M of the polyethylene composition is... n The number average molecular weight is 5,000 to 60,000 g / mol, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the number average molecular weight M of the polyethylene composition is... n The values ​​are 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 20,000 to 30,000 g / mol.

[0162] In one embodiment of this disclosure, the Z-average molecular weight M of the polyethylene composition is... z ≥250,000 g / mol, or ≥275,000 g / mol.

[0163] In another embodiment of this disclosure, the Z-average molecular weight M of the polyethylene composition is... z The value is 250,000 to 600,000 g / mol, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the Z-average molecular weight M of the polyethylene composition is... z The values ​​are 250,000 to 550,000 g / mol, or 250,000 to 500,000 g / mol, or 275,000 to 500,000 g / mol, or 275,000 to 475,000 g / mol, or 275,000 g / mol to 450,000 g / mol.

[0164] In one embodiment of this disclosure, the polyethylene copolymer composition exhibits a bimodal characteristic curve (i.e., a bimodal molecular weight distribution) in gel permeation chromatography (GPC) analysis.

[0165] In one embodiment of this disclosure, the polyethylene copolymer composition exhibits a bimodal characteristic curve in gel permeation chromatography produced according to the method of ASTM D6474-99.

[0166] The term "single peak" is defined herein as meaning that there is only one distinct peak or maximum value in the GPC curve. Conversely, the term "bimodal" is intended to convey that, in addition to the first peak, there will be a second peak or shoulder representing a higher or lower molecular weight component (i.e., the molecular weight distribution, which can be said to have two maximum values ​​in the molecular weight distribution curve). Alternatively, the term "bimodal" refers to the presence of two maximum values ​​in a molecular weight distribution curve produced according to the method of ASTM D6474-99. The term "multimodal" indicates the presence of two or more, typically more than two, maximum values ​​in a molecular weight distribution curve produced according to the method of ASTM D6474-99.

[0167] In embodiments of this disclosure, the molecular weight distribution M of the polyethylene composition w / M n ≤8.0, or <8.0, or ≤7.0, or <7.0, or ≤6.5, or <6.5, or ≤6.0, or <6.0, or 5.5, or <5.5, or ≤5.0, or <5.0. In embodiments of this disclosure, the molecular weight distribution M of the polyethylene composition is... w / M n ≥3.0, >3.0, or ≥3.5, or >3.5.

[0168] In embodiments of this disclosure, the molecular weight distribution M of the polyethylene composition w / M n The molecular weight distribution is from 2.9 to 8.0, including any narrower range within this range and any value encompassed by these ranges. For example, in embodiments of this disclosure, the molecular weight distribution M of the polyethylene composition is... w / M n The values ​​are 2.9 to 7.5, or 3.0 to 7.0, or 3.0 to 6.5, or 3.0 to 6.0, or 3.5 to 7.0, or 3.5 to 6.5, or 3.5 to 6.0, or 3.5 to 5.5, or 3.5 to 5.0.

[0169] In embodiments of this disclosure, the Z-average molecular weight distribution of the polyethylene composition, Mz / Mw, is ≥2.5, ≥2.6, ≥2.7, ≥2.8, >2.5, >2.6, >2.7, or >2.8.

[0170] In embodiments of this disclosure, the Z-mean molecular weight distribution Mz / Mw of the polyethylene composition is from 2.5 to 4.5, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the Z-mean molecular weight distribution Mz / Mw of the polyethylene composition is from 2.5 to 4.0, or 2.7 to 4.0, or 2.8 to 4.0, or 2.5 to 3.8, or 2.5 to 3.5, or 2.8 to 3.8, or 2.8 to 3.5.

[0171] In embodiments of this disclosure, the density of the polyethylene copolymer composition is ≥0.940 g / cm³. 3 or ≥0.941g / cm 3 or ≥0.942g / cm 3 or ≥0.943g / cm 3 .

[0172] In embodiments of this disclosure, the density of the polyethylene composition is from 0.940 to 0.970 g / cm³. 3 This includes any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of this disclosure, the density of the polyethylene composition is from 0.940 to 0.965 g / cm³. 3 Or 0.941 to 0.965 g / cm³ 3 Or 0.940 to 0.962 g / cm³ 3 Or 0.941 to 0.962 g / cm³ 3 Or 0.941 to 0.960 g / cm³ 3 Or 0.941 to 0.957 g / cm³ 3 Or 0.941 to 0.954 g / cm³ 3 Or 0.941 to 0.952 g / cm³ 3 Or 0.940 to 0.960 g / cm³ 3 Or 0.940 to 0.957 g / cm³ 3 Or 0.940 to 0.954 g / cm³ 3 Or 0.940 to 0.952 g / cm³ 3 Or 0.942 to 0.954 g / cm³ 3 Or 0.942 to 0.952 g / cm³ 3 .

[0173] In embodiments of this disclosure, the melt index I2 of the polyethylene composition is from 0.001 to 5.0 g / 10 min, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the melt index I2 of the polyethylene composition may be 0.01 to 5.0 g / 10 min, or 0.1 to 5.0 g / 10 min, or 0.01 to 4.0 g / 10 min, or 0.1 to 4.0 g / 10 min, 0.01 to 2.5 g / 10 min, or 0.1 to 2.5 g / 10 min, or 0.5 to 5.0 g / 10 min, or 0.8 to 5.0 g / 10 min, or 0.5 to 4.0 g / 10 min, or 0.8 to 4.0 g / 10 min, or 0.5 to 2.5 g / 10 min, or 0.8 to 2.5 g / 10 min, or 0.5 to 2.0 g / 10 min, or 0.8 to 2.0 g / 10 min.

[0174] In embodiments of this disclosure, the high-load melt index I of the polyethylene composition 21 The melt flow rate is at least 55 g / 10 min, or at least 60 g / 10 min, or at least 65 g / 10 min, or at least 70 g / 10 min. In another embodiment of this disclosure, the high-load melt index I of the polyethylene composition... 21 The range is 55 to 160 g / 10 min, including any narrower range within this range and any value encompassed by these ranges. For example, in embodiments of this disclosure, the high-load melt index I of the polyethylene composition... 21 The dosage can be 55 to 120g / 10min, or 60 to 120g / 10min.

[0175] In embodiments of this disclosure, the melt flow ratio I of the polyethylene composition 21 / I2≥35, or >35, or ≥40, or >40, or ≥45, or >45. In another embodiment of this disclosure, the melt flow ratio I of the polyethylene composition is... 21 / I2 is 35 to 120, including any narrower range within this range and any value covered by these ranges. For example, in embodiments of this disclosure, the melt flow ratio of the polyethylene composition is I 21 / I2 is 40 to 100, or 45 to 100, or 40 to 90, or 45 to 90.

[0176] In one embodiment of this disclosure, the polyethylene composition will have a reverse or partially reverse comonomer distribution characteristic curve, as measured using GPC-FTIR.

[0177] In one embodiment of this disclosure, the polyethylene composition will have an approximately flat (or uniform) comonomer distribution characteristic curve, as measured using GPC-FTIR.

[0178] If the incorporation of comonomers decreases with increasing molecular weight, as measured using GPC-FTIR, the distribution is described as “normal.” If the incorporation of comonomers is approximately constant with increasing molecular weight, as measured using GPC-FTIR, the comonomer distribution is described as “flat” or “uniform.” The terms “reverse comonomer distribution” and “partially reverse comonomer distribution” mean that in the GPC-FTIR data obtained for the copolymer, there are one or more higher molecular weight fractions with higher comonomer incorporation than one or more lower molecular weight fractions. The term “reverse (of) comonomer distribution” as used herein means that, within the molecular weight range of the ethylene copolymer, the comonomer content of various polymer fractions is substantially non-uniform, and its higher molecular weight fractions have proportionally higher comonomer contents (i.e., if the comonomer incorporation increases with molecular weight, the distribution is described as “reverse” or “reverse”). When the incorporation of comonomers increases with increasing molecular weight and then decreases, the comonomer distribution is still considered “reverse,” but can also be described as “partially reverse.” Partially reversed comonomer distributions will show peaks or maximum values.

[0179] In embodiments of this disclosure, the CDBI of the polyethylene composition 50 The concentration will be greater than 50 wt%, or greater than 55 wt%, or greater than 60 wt%, or greater than 65 wt%, or greater than 70 wt%, or greater than 75 wt%. In embodiments of this disclosure, the CDBI of the polyethylene composition... 50 It is 60wt% to 98wt%, or 70wt% to 90wt%, or 75wt% to 85wt%.

[0180] In embodiments of this disclosure, the upper limit of hafnium in the polyethylene composition (parts per million (ppm) based on the weight of the polyethylene composition) may be about 3.0 ppm, or about 2.5 ppm, 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 this disclosure, the lower limit of hafnium in the polyethylene composition (ppm) 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.

[0181] In embodiments of this disclosure, the polyethylene composition has 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 0.050 to 2.0 ppm of hafnium, or 0.050 to 1.5 ppm of hafnium, or 0.050 to 1.5 ppm of hafnium. 0.0 ppm, or 0.050 to 0.75 ppm, 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 0.75 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.

[0182] In embodiments of this disclosure, the polyethylene composition has 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.

[0183] In one embodiment of this disclosure, the polyethylene composition contains long-chain branches characterized by the long-chain branching factor (LCBF) disclosed herein. In embodiments of this disclosure, the upper limit of the LCBF of the polyethylene composition may be 0.5000, or 0.4000, or 0.3000 (dimensionless). In embodiments of this disclosure, the lower limit of the LCBF of the polyethylene composition may be 0.0010, or 0.0015, or 0.0020, or 0.0100, or 0.0500, or 0.1000 (dimensionless).

[0184] In embodiments of this disclosure, the LCBF of the polyethylene composition 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, or at least 0.0200, or at least 0.0250.

[0185] In embodiments of this disclosure, the LCBF of the polyethylene composition may be >0.0010, >0.0050, >0.0100, or >0.0200 (dimensionless).

[0186] In embodiments of this disclosure, the LCBF of the polyethylene composition may be 0.0010 to 0.5000, or 0.0010 to 0.1000, or 0.0050 to 0.5000, or 0.0050 to 0.1000, or 0.0070 to 0.5000, or 0.0050 to 0.2500, or 0.0070 to 0.2500, or 0.0100 to 0.5000, or 0.0100 to 0.2500, or 0.0050 to 0.1000, or 0.0070 to 0.1000, or 0.0100 to 0.1000, or 0.0050 to 0.1500, or 0.0070 to 0.1500, or 0.0100 to 0.1500.

[0187] In one embodiment of this disclosure, the polyethylene composition is defined as Log 10 [I6 / I2] / Log 10 The stress index of [6.48 / 2.16] is ≥1.40. In another embodiment of this disclosure, the stress index Log of the polyethylene composition is... 10 [I6 / I2] / Log 10 [6.48 / 2.16] Greater than 1.42, or greater than 1.45, or greater than 1.50.

[0188] In embodiments of this disclosure, the polyethylene composition is defined as Log 10 [I6 / I2] / Log 10 The stress index of [6.48 / 2.16] is 1.45 to 1.80, or 1.50 to 1.80, or 1.50 to 1.75.

[0189] In one embodiment of this disclosure, in a temperature elution fractionation (TREF) analysis obtained using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at temperatures greater than 90°C with an integral area greater than 65% by weight. In another embodiment of this disclosure, in a temperature elution fractionation (TREF) analysis obtained using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at temperatures greater than 90°C with an integral area greater than 70% by weight. In yet another embodiment of this disclosure, in a temperature elution fractionation (TREF) analysis obtained using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at temperatures greater than 90°C with an integral area greater than 75% by weight.

[0190] In one embodiment of this disclosure, in a temperature elution fractionation (TREF) analysis obtained using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at 90°C to 98°C with an integral area greater than 50% by weight. In one embodiment of this disclosure, in a temperature elution fractionation (TREF) analysis obtained using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at 90°C to 98°C with an integral area greater than 60% by weight. In one embodiment of this disclosure, in a temperature elution fractionation (TREF) analysis obtained using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at 90°C to 98°C with an integral area greater than 70% by weight. In one embodiment of this disclosure, in temperature elution fractionation (TREF) analysis obtained, such as using a CTREF instrument (“CRYSTAF” instrument), the polyethylene composition has fractions eluted at 90°C to 98°C with an integral area greater than 75% by weight.

[0191] Additives may be added to the polyethylene composition during the extrusion or compounding step, 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 step. Suitable additives are known in the art and include, but are not limited to, antioxidants, phosphites and phosphonites, nitrones, acid stabilizers, UV light stabilizers, UV absorbers, metal passivators, dyes, fillers and reinforcing agents, nanoscale organic or inorganic materials, antistatic agents, lubricants such as calcium stearate, slip additives such as erucimide, and nucleating agents (including nucleating agents, pigments, or any other chemicals that can provide a nucleating effect to the polyethylene composition). Additives that may be optionally added are typically added in amounts of up to 20% by weight (wt%).

[0192] One or more nucleating agents can be introduced into a polyethylene composition by kneading a mixture of polymer, typically in powder or granule form, with the nucleating agent. The nucleating agent can be used alone or as a concentrate containing additional additives such as stabilizers, pigments, antistatic agents, UV stabilizers, and fillers. It should be a material that is wetted or absorbed by the polymer, insoluble in the polymer, and has a melting point higher than the polymer's melting point, and should be uniformly dispersed in the polymer melt in the finest possible form (1 to 10 μm). Compounds known to have nucleating ability for polyolefins include salts of aliphatic monobasic or dibasic acids or arylalkyl acids, such as sodium succinate or aluminum phenylacetate; and alkali metal salts or aluminum salts of aromatic or alicyclic carboxylic acids, such as sodium β-naphthoate. Another known compound with nucleating ability is sodium benzoate. The effectiveness of nucleation can be monitored under a microscope by observing the reduction in the size of the spherulites formed by grain aggregation.

[0193] Examples of commercially available nucleating agents that can be added to polyethylene compositions are dibenzyl sorbitol esters (such as those marketed by Milliken Chemical under the trademark). Products sold by 3988 and trademarked by Ciba Specialty Chemicals (Products for sale). Other examples of nucleating agents that can be added to polyethylene compositions include cyclic organic structures (and their salts, such as disodium bicyclic [2.2.1]hepten dicarboxylate) disclosed in U.S. Patent No. 5,981,636; saturated forms of the structures disclosed in U.S. Patent No. 5,981,636 (such as those disclosed in U.S. Patent No. 6,465,551; Zhao et al., granted to Milliken); salts of certain cyclic dicarboxylic acids having a hexahydrophthalic acid structure (or “HHPA” structure) as disclosed in U.S. Patent No. 6,599,971 (Dotson et al., granted to Milliken); and phosphate esters, such as those disclosed in U.S. Patent No. 5,342,868 and those sold by Asahi Denka Kogyo under the trade names NA-11 and NA-21; cyclic dicarboxylic acid esters and their salts, such as divalent metal or metalloid salts (especially calcium salts) of the HHPA structure disclosed in U.S. Patent No. 6,599,971. For clarity, an HHPA structure typically comprises a ring structure having six carbon atoms and two carboxylic acid groups, which are substituents on adjacent atoms of the ring structure. The other four carbon atoms in the ring can be substituted, as disclosed in U.S. Patent No. 6,599,971. An example is calcium 1,2-cyclohexanedicarboxylate (CAS Registry No. 491589-22-1). Further examples of nucleating agents that can be added to polyethylene compositions include those disclosed in WO2015042561, WO2015042563, WO2015042562, and WO 2011050042.

[0194] Many of the aforementioned nucleating agents may be difficult to mix with the nucleating polyethylene composition, and dispersing aids, such as zinc stearate, are known to be used to mitigate this problem.

[0195] In one embodiment of this disclosure, the nucleating agent is well dispersed in the polyethylene composition.

[0196] In embodiments of this disclosure, the amount of nucleating agent used is relatively small (5 to 3000 ppm / weight (based on the weight of the polyethylene composition)), and therefore those skilled in the art will understand that care must be taken to ensure good dispersion of the nucleating agent. In embodiments of this disclosure, the nucleating agent is added to the polyethylene composition in a finely ground form (less than 50 micrometers, especially less than 10 micrometers) to promote mixing. In some embodiments, this type of “physical blend” (i.e., a mixture of nucleating agent and resin in solid form) may preferably use a “masterbatch” of the nucleating agent (where the term “masterbatch” refers to the practice of first melt-mixing the additive—in this case, the nucleating agent—with a small amount of polyethylene composition resin and then melt-mixing the “masterbatch” with the remaining large amount of polyethylene composition resin).

[0197] In embodiments of this disclosure, additives such as nucleating agents may be added to the polyethylene composition as a “masterbatch”, wherein the term “masterbatch” refers to the practice of first melt-mixing the additive (e.g., nucleating agent) with a small amount of the polyethylene composition, and then melt-mixing the “masterbatch” with the remaining large amount of the polyethylene composition.

[0198] In one embodiment of this disclosure, the polyethylene composition further comprises a nucleating agent or a mixture of nucleating agents.

[0199] Biaxial orientation method

[0200] In one embodiment of this disclosure, the biaxially oriented polyethylene film or biaxially oriented polyethylene film structure comprises a polyethylene composition prepared according to this disclosure.

[0201] In one embodiment of this disclosure, biaxially oriented polyethylene (BOPE) films or film structures can be manufactured using a tenter frame process.

[0202] The tenter frame method is commonly used to prepare biaxially oriented films and is applicable to the embodiments of this disclosure. The tenter frame method is well known to those skilled in the art of film manufacturing. The method begins with an extruder equipped with a slotted die to form a sheet or film. For convenience, such an extruded sheet or film may be referred to as a “base film” or “base film structure” or “base structure.” Once the base structure is quenched on cooling rollers, it is reheated and machine-directed (MD) stretching or machine-directed orientation (MDO) is achieved by pulling the base structure using several closely spaced rollers rotating at progressively increasing surface speeds. After MD stretching, a clamp (attached to a chain) holds the edges of the moving sheet (or film or web) and guides it into an oven. In the oven, the edges of the base structure are pulled apart, making the sheet wider, thereby providing transverse orientation (TDO). Orientation / stretching causes the film structure to become thinner proportionally to the orientation or stretching ratio. For example, to prepare a 1-mil finished BOPE film with a stretch ratio of 5:1 in the machine direction (MD) and 8:1 in the transverse direction (TD), the method can begin with a film or sheet 40 mils thick.

[0203] In embodiments of this disclosure, the draw ratio in the machine direction (MD) can range from about 5:1 to about 9:1, while the draw ratio in the transverse direction (TD) can range from about 7:1 to 12:1. In other embodiments of this disclosure, the draw ratio in the machine direction (MD) can range from about 3:1 to about 12:1, while the draw ratio in the transverse direction (TD) can range from about 3:1 to 12:1. In still other embodiments of this disclosure, the draw ratio in the machine direction (MD) can range from about 5:1 to about 12:1, while the draw ratio in the transverse direction (TD) can range from about 5:1 to 12:1. In yet still other embodiments of this disclosure, the draw ratio in the machine direction (MD) can range from about 3:1 to about 10:1, while the draw ratio in the transverse direction (TD) can range from about 3:1 to 10:1.

[0204] Further details of the biaxial orientation method are provided by Kanai T. et al. in the textbook “Film Processing Advances” (2014), Hanser Publishers, but the typical sequential biaxial orientation method will include: casting a relatively thick base film structure from a slot die, followed by cooling on a cooler (or in a water bath); stretching the base film structure in the machine direction using heated rollers rotating at progressively increasing speeds; stretching the film structure laterally by pulling each edge of the film structure with clamps attached to the edges of the film structure, wherein the clamps further move apart to pull the edges of the clamped film laterally as the film is pulled forward (i.e., stretching occurs laterally perpendicular to the machine direction); annealing the film structure in an oven; performing optional surface treatments on the film structure; trimming the unstretched edges of the film structure held by the clamps; and winding the film structure.

[0205] Although sequential biaxial stretching is employed in the embodiments of this disclosure, in some embodiments, sequential biaxial orientation may lead to film quality problems. For example, in some embodiments, the optics of the film or multilayer film structure may be damaged. Therefore, for some embodiments, alternative unit operations may be preferred, which involve performing machine orientation / lateral stretching simultaneously in a single method step. During simultaneous stretching, the substrate film may be held and suspended in the air by a tenter frame fixture (as described above), stretching simultaneously in both the MD and TD directions.

[0206] In one embodiment, the polyethylene composition prepared according to the present disclosure is used to prepare a BOPE film or membrane structure.

[0207] In one embodiment, the BOPE membrane or membrane structure is prepared from 60% to 100% by weight (based on the total weight of the membrane or membrane structure) of a polyethylene composition prepared according to the present disclosure. In one embodiment, the BOPE membrane or membrane structure is prepared from 70% to 90% by weight (based on the total weight of the membrane or membrane structure) of a polyethylene composition prepared according to the present disclosure. In one embodiment, the BOPE membrane or membrane structure is prepared from 80% to 95% by weight (based on the total weight of the membrane or membrane structure) of a polyethylene composition prepared according to the present disclosure.

[0208] In one embodiment, the "all-polyethylene" BOPE membrane or membrane structure is prepared from at least 90% by weight (based on the weight of the polymer material used in the membrane or membrane structure) of the polyethylene composition described herein. In one embodiment, the "all-polyethylene" BOPE membrane or membrane structure is prepared from at least 95% by weight (based on the weight of the polymer material used in the membrane or membrane structure) of the polyethylene composition described herein. In one embodiment, the "all-polyethylene" BOPE membrane or membrane structure is prepared from at least 99% by weight (based on the weight of the polymer material used in the membrane or membrane structure) of the polyethylene composition described herein. In one embodiment, the "all-polyethylene" BOPE membrane or membrane structure is prepared from 100% by weight (based on the weight of the polymer material used in the membrane or membrane structure) of the polyethylene composition described herein.

[0209] In one embodiment, the BOPE membrane or membrane structure is prepared from 60% to 100% by weight (based on the total weight of the membrane or membrane structure) of a polyethylene composition prepared according to the present disclosure, wherein one or more residual polymers used to prepare the BOPE membrane or membrane structure are also polyethylene. In one embodiment, the BOPE membrane or membrane structure is prepared from 70% to 90% by weight (based on the total weight of the membrane or membrane structure) of a polyethylene composition prepared according to the present disclosure, wherein one or more residual polymers used to prepare the BOPE membrane or membrane structure are also polyethylene. In one embodiment, the BOPE membrane or membrane structure is prepared from 80% to 95% by weight (based on the total weight of the membrane or membrane structure) of a polyethylene composition prepared according to the present disclosure, wherein one or more residual polymers used to prepare the BOPE membrane or membrane structure are also polyethylene. It is not desirable to be bound by theory; using only polyethylene to prepare the BOPE membrane or membrane structure makes the membrane more easily recyclable compared to membranes prepared with mixtures of polymers.

[0210] The use of polymer blends is known in the field of BOPE membrane preparation, and this is also considered in some embodiments of this disclosure. Therefore, in one embodiment of this disclosure, the BOPE membrane or membrane structure is prepared from a polymer blend composition comprising at least 60% by weight of a polyethylene composition prepared according to this disclosure.

[0211] Some non-limiting examples of other polymers suitable for blending with polyethylene compositions in the embodiments of this disclosure include: linear low-density polyethylene (LLDPE); medium-density polyethylene (MDPE); high-density polyethylene (HDPE); very low-density polyethylene (VLDPE), including elastomers and plasmons; and high-pressure low-density polyethylene (HPLDPE) prepared by free radical polymerization of ethylene.

[0212] In embodiments of this disclosure, the LLDPE used in the polymer blend with the polyethylene composition has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.9 to 2.3 g / 10 min, and a density of about 0.910 to about 0.935 g / cm³. 3 .

[0213] In embodiments of this disclosure, the VLPDE used in the polymer blend with the polyethylene composition has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.9 to 2.3 g / 10 min, and a density of about 0.890 to about 0.910 g / cm³. 3 .

[0214] In embodiments of this disclosure, the MDPE used in the polymer blend with the polyethylene composition has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.9 to 2.3 g / 10 min, and a density of about 0.936 to about 0.949 g / cm³. 3 .

[0215] In embodiments of this disclosure, the HDPE used in the polymer blend with the polyethylene composition has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.4 to 0.9 g / 10 min, and a density of at least about 0.95 g / cm³. 3 .

[0216] In embodiments of this disclosure, the HPLDPE used in the polymer blend with the polyethylene composition has a melt index (I2) of 0.1 to 10 g / 10 min and a density of about 0.92 to about 0.94 g / cm³. 3 .

[0217] In the field of BOPE membrane fabrication, the use of multilayer membranes or membrane structures as (unstretched) starting membranes is known. These starting membranes are relatively thick before stretching and are often referred to as "sheets" rather than membranes. For convenience, such unstretched multilayer sheets may be called "base membranes," "base membrane structures," or "base structures."

[0218] In one embodiment of this disclosure, a suitable basement membrane structure will comprise at least 60% by weight of a polyethylene composition prepared as described herein (based on the total weight of the basement membrane structure).

[0219] In one embodiment of this disclosure, the polyethylene composition prepared as described herein is used as a “core” layer (i.e., as an inner layer of a multilayer basement membrane structure) in a suitable basement membrane structure. In embodiments of this disclosure, polymers that can be used to prepare other layers in a suitable basement membrane structure include the aforementioned LLDPE, MDPE, HDPE, VLPDE, and HPLDPE.

[0220] In one embodiment of this disclosure, the multilayer basement membrane structure comprises at least three layers, including two surface layers (i.e., layers on each outer surface of the basement membrane structure) and one or more core layers.

[0221] In one embodiment of this disclosure, one surface layer may be made of HDPE, while the other surface layer is a sealing layer, as disclosed in published U.S. Patent No. 9,676,169.

[0222] In one embodiment of this disclosure, the sealing layer may comprise: linear low-density polyethylene (LLDPE) (e.g., LLDPE prepared with so-called metallocene catalysts, which are well known to those skilled in the art); a plastomer; an elastomer; or a blend thereof.

[0223] In one embodiment, a plasmon comprising polymerized ethylene and 1-octene monomers (and blends thereof with LLDPE, HDPE and / or HPLDPE) may also be used in the sealing layer.

[0224] In one embodiment of this disclosure, the use of a plastomer (or a polymer blend thereof) in both outer layers of the BOPE film is also contemplated.

[0225] To avoid being bound by theory, the use of plasmons in the surface layer can improve the optical properties of BOPE films.

[0226] In one embodiment of this disclosure, the BOPE membrane has a core layer comprising a polyethylene composition prepared as described herein, while both outer layers comprise a plastic body containing polymerized ethylene and 1-octene monomers.

[0227] In one embodiment of this disclosure, the BOPE membrane has a core layer comprising a polyethylene composition prepared as described herein, and two surface layers also comprising a polyethylene composition prepared as described herein.

[0228] In one embodiment of this disclosure, the BOPE membrane or membrane structure comprises at least three layers, and each layer contains a polyethylene composition prepared as described herein.

[0229] In one embodiment of this disclosure, the BOPE membrane or membrane structure comprises at least three adjacent layers, and each layer contains the polyethylene composition described herein.

[0230] In one embodiment of this disclosure, the BOPE membrane or membrane structure comprises at least three layers, and each layer comprises: i) 50% to 99% by weight of the polyethylene composition described herein; and ii) 50% to 1% by weight of polyethylene selected from LLDPE; MDPE; HDPE; VLPDE; and HPLDPE.

[0231] In one embodiment of this disclosure, a multilayer structure comprising at least five layers has two outer surface layers made of plastide and two “adjacent surface” layers made of a blend of plastide and polyethylene with a density higher than that of plastide.

[0232] It is known to use a "barrier resin" layer to improve the barrier properties of BOPE films. Non-limiting examples of suitable barrier resins include ethylene-vinyl alcohol (EVOH) and polyamides.

[0233] In one embodiment of this disclosure, the surface of the BOPE membrane or membrane structure is metallized.

[0234] In one embodiment of this disclosure, the surface of the BOPE membrane or membrane structure is metallized after surface treatment.

[0235] During metallization, the BOPE film can be placed in a vacuum chamber for physical vapor deposition (PVD) metallization using a metal source (e.g., a metal itself or a metal oxide). The PVD metallization process adds a metal layer to the surface layer of the film or film structure by heating the metal or metal-containing substrate to a high temperature under vacuum. In PVD metallization, evaporation of the metal or metal-containing substrate occurs, followed by condensation of the metal or metal-containing substrate onto the surface of the film or film structure. Metals that can be added to the BOPE film using vapor deposition metallization include, for example, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, silver, nickel, copper, zinc, gold, and palladium, or mixtures thereof. In embodiments of this disclosure, the thickness of the metallization layer (i.e., the deposited metal layer) can be 100 to 5000 angstroms, or 300 to 3000 angstroms.

[0236] In one embodiment of this disclosure, the surface of the BOPE membrane or membrane structure is metallized by physical vapor deposition (PVD) with aluminum.

[0237] In specific embodiments, the polymers used in this disclosure (including polyethylene compositions prepared as described herein) will contain conventional amounts of antioxidants (such as hindered phenols; hypophosphites, or blends of both), as is well known to those skilled in the art. Other optional additives that may be added to the polymers (including polyethylene compositions prepared as described herein) in specific embodiments include anti-blocking agents, slip agents, and nucleating agents (such as those disclosed in U.S. Patent No. 9,676,169). The use of zinc glycerate as an optional nucleating agent is also considered in specific embodiments of this disclosure (note: zinc glycerate nucleating agents are trademarked). (Purchased for 287).

[0238] In one embodiment of this disclosure, the surface of the BOPE membrane or membrane structure is surface-treated. Without being bound by theory, surface treatment can make the surface more suitable for or accept metallization, coatings, printing inks, adhesives, and / or lamination.

[0239] In embodiments of this disclosure, the surface of the BOPE membrane or membrane structure is treated by corona discharge radiation, flame or polarized flame, plasma or chemical treatment.

[0240] The BOPE film prepared according to this disclosure is suitable for a variety of packaging applications. In one embodiment, the BOPE film can be used in a laminated structure; for example, the BOPE film can be used as a printing web when laminated onto a sealing web made of low-density polyethylene. This type of laminated structure is easier to recycle than conventional laminated structures that include polyester or polypropylene layers laminated onto polyethylene layers.

[0241] The following embodiments are provided for the purpose of illustrating selected embodiments of this disclosure. It should be understood that the provided embodiments do not limit the scope of the provided claims.

[0242] Example

[0243] Polymer characterization and testing methods

[0244] Prior to testing, each polymer sample was conditioned at 23±2°C and 50±10% relative humidity for at least 24 hours, and subsequent tests were performed at 23±2°C and 50±10% relative humidity. In this document, the term "ASTM conditions" refers to a laboratory maintained at 23±2°C and 50±10% relative humidity; and the samples to be tested were conditioned in this laboratory for at least 24 hours prior to testing. ASTM refers to the American Society for Testing and Materials.

[0245] density

[0246] Polymer density was determined using ASTM D792-13 (November 1, 2013).

[0247] Melt index

[0248] The polymer melt index was determined using ASTM D1238 (August 1, 2013). Melt indices I2, I6, and I... 10 and I 21 Measurements were taken at 190°C using weights of 2.16 kg, 6.48 kg, 10 kg, and 21.6 kg, respectively. In this paper, the term "stress index" or its abbreviation "S.Ex." is defined by the following relationship:

[0249] S.Ex.=log(I6 / I2) / log(6480 / 2160)

[0250] Wherein 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; these units are equivalent.

[0251] Neutron activation (elemental analysis)

[0252] The catalyst metal residue in the polymer was determined using neutron activation analysis (hereinafter referred to as NAA) as follows: A radiation vial (composed of ultrapure polyethylene, internal volume 7 mL) was filled with the polyethylene composition sample, and the sample weight was recorded. The sample was then placed into a SLOWPOKE tube using a pneumatic transfer system. TM The reactor (Atomic Energy of Canada Limited, Ottawa, Ontario, Canada) is irradiated with elements having short half-lives (e.g., Ti, V, Al, Mg, and Cl) for 30 to 600 seconds, or with elements having long half-lives (e.g., Zr, Hf, Cr, Fe, and Ni) for 3 to 5 hours. The average thermal neutron flux within the reactor is 5 × 10⁻⁶. 11 / cm 2 / s. After irradiation, the sample was removed from the reactor and aged to allow for radioactive decay; elements with short half-lives were aged for 300 seconds, while elements with long half-lives were aged for several days. After aging, the gamma-ray spectra of the sample were recorded using a germanium semiconductor gamma-ray detector (Ortec GEM55185, Advanced Measurement Technology Inc., Oak Ridge, TN, USA) and a multichannel analyzer (Ortec DSPEC Pro). The amount of each element in the sample was calculated from the gamma-ray spectra and recorded in parts per million relative to the total weight of the polyethylene composition sample. The NAA system was calibrated with Specpure standards (1000 ppm of a solution of the desired element (purity >99%)). 1 mL of the solution (element of interest) was aspirated onto a 15 mm × 800 mm rectangular filter paper and air-dried. The filter paper was then placed in a 1.4 mL polyethylene irradiation vial and analyzed using the NAA system. The sensitivity of the NAA procedure (in counts / µg) was determined using standards.

[0253] Gel permeation chromatography (GPC)

[0254] Polyethylene composition sample (polymer) solutions (1 to 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. An antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture to stabilize the polymer and prevent oxidative degradation. The BHT concentration was 250 ppm. The polymer solution was analyzed at 140 °C using a PL 220 high-temperature chromatography unit equipped with four Shodex columns (HT803, HT804, HT805, and HT806), with TCB as the mobile phase and a flow rate of 1.0 mL / min, using differential refractive index (DRI) as the concentration detector. BHT was added to the mobile phase at a concentration of 250 ppm to protect the GPC column from oxidative degradation. The sample injection volume was 200 μL. The GPC column was calibrated using narrow-distribution polystyrene standards. As described in ASTM standard test method D6474-12 (December 2012), the Mark-Houwink equation is used to convert the molecular weight of polystyrene to that of polyethylene. GPC raw data is used... GPC software processing generates the average molar mass (M) n M w M z ) and molar mass distribution (e.g., polydispersity, M w / M n In the polyethylene industry, the commonly used term equivalent to GPC is SEC, which stands for size exclusion chromatography.

[0255] Triple Detection Size Exclusion Chromatography (3D-SEC)

[0256] Polyethylene composition sample (polymer) solutions (1 to 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. An antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture to stabilize the polymer and prevent oxidative degradation. The BHT concentration was 250 ppm. The sample solution was chromatographically analyzed at 140 °C on a PL220 high-temperature chromatography unit equipped with a differential refractive index (DRI) detector, bi-angle light scattering detectors (15 and 90 degrees), and a differential viscometer. The SEC columns used were four Shodex columns (HT803, HT804, HT805, and HT806), or four PL mixed ALS or BLS columns. TCB was 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 were processed using CIRRUS GPC software to produce absolute molar mass and intrinsic viscosity ([η]). The term "absolute" molar mass is used to distinguish between the absolute molar mass determined by 3D-SEC and the molar mass determined by conventional SEC. The viscosity-average molar mass (Mn) determined by 3D-SEC is used in the calculations. v To determine the long chain branching factor (LCBF).

[0257] GPC-FTIR

[0258] A polyethylene composition (polymer) solution (2 to 4 mg / mL) was 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. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture to stabilize the polymer and prevent oxidative degradation. The BHT concentration was 250 ppm. The sample solution was chromatographically analyzed at 140 °C on a Waters GPC 150C chromatographic unit equipped with four Shodex columns (HT803, HT804, HT805, and HT806) using TCB as the mobile phase at a flow rate of 1.0 mL / min. An FTIR spectrometer and a heated FTIR flow cell coupled to the chromatographic unit via a heated transfer line were used as the detection system. 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 300 μL. The raw FTIR spectra were processed using OPUS FTIR software, and the polymer concentration and methyl content were calculated in real time using OPUS-related chemometric software (PLS technology). The polymer concentration and methyl content were then acquired and baseline corrected using CIRRUS GPC software. The SEC column was calibrated using narrow-distribution polystyrene standards. The polystyrene molecular weight was converted to the polyethylene molecular weight using the Mark-Houwink equation, as described in ASTM standard test method D6474. The comonomer content was calculated based on the polymer concentration and methyl content predicted by PLS technology, as described in Paul J. DesLauriers, Polymer 43, pp. 159–170 (2002), which is incorporated herein by reference.

[0259] Short Chain Branch - GPC - FTIR

[0260] Short-chain branching per 1000 carbon atoms is measured relative to copolymer fractions of different molecular weights. When plotted on a semi-logarithmic scale, the slant lines (from low to high molecular weight fractions on the logarithmic x-axis and the number of short-chain branches on the vertical y-axis) represent the distribution of short-chain branching for different molecular weight fractions as determined by Fourier transform infrared (FTIR) spectroscopy. The GPC-FTIR method measures the total methyl content, which includes methyl groups located at the ends of each macromolecular chain, i.e., methyl terminal groups. Therefore, the raw GPC-FTIR data must be corrected by subtracting the contribution from the methyl terminal groups. More clearly, the raw GPC-FTIR data overestimate the amount of short-chain branching (SCB), and this overestimation increases as the molecular weight (M) decreases. In this disclosure, 2-methyl correction is used to correct the raw GPC-FTIR data. At a given molecular weight (M), the number of methyl terminal groups (N) ECalculate using the following equation: N E =28000 / M, and N is subtracted from the original GPC-FTIR data. E (M-dependent) to produce SCB / 1000C (2-methyl corrected) GPC-FTIR data.

[0261] Unsaturated content

[0262] The amount of unsaturated groups (i.e., double bonds) in the polyethylene composition was determined according to ASTM D3124-98 (Vinylene Unsaturation, March 2011) and ASTM D6248-98 (Vinyl and Trans Unsaturation, July 2012). Ethylene interpolymer samples were prepared by: a) first undergoing carbon disulfide extraction to remove additives that might interfere with the analysis; b) pressing the sample (in granule, film, or particle form) into a plate of uniform thickness (0.5 mm); and c) analyzing the plate by FTIR.

[0263] Comonomer content: Fourier transform infrared (FTIR) spectrum

[0264] The amount of comonomer in the polyethylene composition was determined by FTIR and recorded as the content of short-chain branching (SCB) with dimensions CH3# / 1000C (the number of methyl branches per 1000 carbon atoms). This test was performed according to ASTM D6645-01 (2001) using a compression-molded polymer sheet and a Thermo-Nicolet 750 Magna-IR spectrophotometer. The polymer sheet was prepared according to ASTM D4703-16 (April 2016) using a compression molding apparatus (Wabash-Genesis series press).

[0265] Differential scanning calorimetry (DSC)

[0266] DSC testing is typically performed according to ASTM D3418. This analysis is conducted by subjecting a polymer sample (5-10 mg prepared in an aluminum pan) and a reference material (empty aluminum pan) to a constant rate of temperature change within the DSC cell. The actual temperatures of the sample and reference are monitored by the instrument as the sample temperature increases or decreases linearly over time. If the sample undergoes a transition, reaction, or transformation, its rate of temperature change will differ from that of the reference. The instrument is first calibrated with indium (TA Instruments Q2000); after calibration, the polymer sample is equilibrated at 0°C and then heated to 200°C at a heating rate of 10°C / min; the melt is then held isothermally at 200°C for five minutes; the melt is then cooled to 0°C at a cooling rate of 10°C / min and held at 0°C for five minutes; the sample is then heated to 200°C at a heating rate of 10°C / min. The temperature difference between the sample and the reference (DT = T) is then recorded.参考物 -T 样品 Plot the temperature relative to the sample temperature to generate a differential thermal analysis (DTA) graph. From this graph, determine the melting peak temperature (°C), enthalpy of fusion (J / g), and crystallinity (%).

[0267] Dynamic mechanical analysis (DMA)

[0268] Oscillatory shear measurements were performed at small strain amplitudes to obtain linear viscoelastic functions at 5 out of every 10 points within a frequency range of 0.02–126 rad / s at 190 °C in a N2 atmosphere, with a strain amplitude of 10%. Frequency sweep experiments were conducted using a TA Instruments DHR3 stress-controlled rheometer with a conical geometry having a cone angle of 5°, an intercept of 137 μm, and a diameter of 25 mm. In this experiment, sinusoidal strain waves were applied, and the stress response was analyzed based on the linear viscoelastic function. 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).

[0269] Shear thinning index SHI (0.5,50) The complex viscosity is calculated as the ratio of the estimated complex viscosity at a shear stress of 0.5 kPa to that at a shear stress of 50 kPa. Shear thinning index (SHI) (0.5,50) This provides information about the shear-thinning behavior of the polymer melt. High values ​​indicate a strong dependence of viscosity on changes in deformation rate (shear or frequency).

[0270] In this disclosure, the LCBF (long chain branching factor) is determined using η0 as measured by DMA (see U.S. Patent No. 10,442,921).

[0271] Capillary Rheology

[0272] Use from The LCR7000 capillary rheometer obtains rheological data to acquire viscosity characteristic curves of different resins at different shear rates. In the capillary extrusion rheometer, the material is held in a temperature-controlled cylinder and forced through a precisely sized die by a piston. The orifice size, die size, and piston speed determine the apparent rate of shear applied to the material, and the apparent shear stress is calculated using the force and die size. Shear viscosity can be obtained using Poiseuille's law via capillary flow methods.

[0273]

[0274]

[0275] Where P = the pressure drop across the capillary (N / m) 2 R = radius of capillary (m); L = length of capillary (m); Q = volumetric flow rate (m³ / s). 3 / sec); σ s = Apparent shear stress;

[0276] The shear rate, shear stress, and shear viscosity determined using the Poiseuille equation are commonly referred to as apparent shear viscosity, shear stress, and shear rate. This is because the non-Newtonian characteristics of most fluids and the pressure drop across the inlet and outlet pressures of the die are not considered. The test temperature was set at 200°C. In this evaluation, the capillary length used was 30.48 mm, and the die diameter was 1.524 mm.

[0277] melt strength

[0278] Melt strength was measured at 190°C using a Rosand RH-7 capillary rheometer (barrel diameter = 15 mm) with a flat die of 2 mm diameter and an L / D ratio of 10:1. Pressure sensor: 10,000 psi (68.95 MPa). Piston speed: 5.33 mm / min. Traction angle: 52°. Traction increment speed: 50-80 m / min 2 Or 65±15m / min 2 The polymer melt is extruded through a capillary die at a constant rate and then stretched at an increasing traction speed until it breaks. The maximum stable value of the force in the plateau region of the force-time curve is defined as the melt strength of the polymer.

[0279] Vicat softening point (temperature)

[0280] The Vicat softening point of the polyethylene composition samples was determined according to ASTM D1525-07 (released December 2009). This test determines the temperature at which the specified penetration occurs when the sample is subjected to the ASTM D1525-07 test conditions, namely heating rate B (120 ± 10 °C / h and 938 g load (10 ± 0.2 N load)).

[0281] CYTSAF / TREF(CTREF)

[0282] The compositional width index (hereinafter referred to as CDBI) of the polyethylene compositions (and comparative examples) was measured using a CRYSTAF / TREF 200+ unit (hereinafter referred to as CTREF) equipped with an IR detector. The abbreviation "TREF" refers to temperature elution fractionation. CTREF was supplied by Polymer Characterization, SA (Valencia Technology Park, Gustave Eiffel, 8, Paterna, E-46980 Valencia, Spain). CTREF operates in TREF mode, which produces the chemical composition of the polymer sample as elution temperature, Co / Ho ratio (polymer / homopolymer ratio), and CDBI (compositional width index). 50 and CDBI 25 The polymer sample (80 to 100 mg) was placed in a CTREF reactor vessel. The reactor vessel was filled with 35 mL of 1,2,4-trichlorobenzene (TCB), and the polymer was dissolved by heating the solution to 150 °C for 2 hours. Aliquots (1.5 mL) of the solution were then loaded into a CTREF column packed with stainless steel beads. The column with the sample was allowed to stabilize at 110 °C for 45 minutes. The polymer was then crystallized from the solution by cooling to 30 °C at a cooling rate of 0.09 °C / min within the column. The column was then equilibrated at 30 °C for 30 minutes. The crystallized polymer was then eluted from the column with TCB flowing through it at 0.75 mL / min, while the column was slowly heated from 30 °C to 120 °C at a heating rate of 0.25 °C / min. The raw CTREF data were processed using PolymerChar software, an Excel spreadsheet, and internally developed CTREF software. CDBI 50 Defined as the percentage of a polymer whose composition comprises within 50% of the median comonomer composition; CDBI 50It is calculated from the composition distribution curve and the normalized cumulative integral of the composition distribution curve, as described in U.S. Patent 5,376,439. Those skilled in the art will understand that a calibration curve is needed to convert the CTREF elution temperature into comonomer content, i.e., the amount of comonomer in the ethylene / α-olefin polymer fraction eluted at a specific temperature. The generation of such calibration curves is described in the prior art, for example, Wild et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20(3), pp. 441-455; which are hereby fully incorporated by reference. CDBI 25 Calculated in a similar manner; CDBI 25 Defined as the percentage of polymer comprising 25% of the median comonomer. At the end of each sample run, the CTREF column was cleaned for 30 minutes; specifically, the CTREF column temperature was 160°C, and TCB was flowed through the column (0.5 mL / min) for 30 minutes.

[0283] The CTREF procedure described above is well known to those skilled in the art and can be used to determine the shape of the TREF characteristic curve and CDBI. 50 CDBI 25 The amount (by weight percentage) of material in the polyethylene composition eluted above 90°C (i.e., the relative area of ​​the eluted fractions appearing in the TREF characteristic curve at 90°C and above), the amount (by weight percentage) of material in the polyethylene composition eluted at temperatures between 90°C and 98°C (i.e., the relative area of ​​the eluted fractions appearing in the TREF characteristic curve at temperatures between 90°C and 98°C), and the temperature or temperature range at which the maximum elution intensity (elution peak) occurs.

[0284] Long-chain branching factor (LCBF)

[0285] The LCBF (dimensionless) of the polyethylene composition was determined using the method described in U.S. Patent No. 10,442,921, which is incorporated herein by reference.

[0286] The calculation of the long chain branching factor (“LCBF”) requires polydispersity correction for zero shear viscosity (ZSV). c Intrinsic viscosity (IV) corrected for short-chain branching (“SCB”) and short-chain branching (“SCB”). c (as fully described in the following paragraphs).

[0287] As shown in equation Eq.(1), for the dimensionless zero-shear viscosity ZSV... c Corrections were made:

[0288]

[0289] Where η0 is the zero-shear viscosity (poise), measured by DMA as described above; Pd is the dimensionless polydispersity (Mn) as measured using conventional GPC as described above. w / M n ), and 1.8389 and 2.4110 are dimensionless constants.

[0290] As shown in equation Eq.(2), for an intrinsic viscosity IV with dimensions dL / g... c Corrections were made:

[0291]

[0292] The intrinsic viscosity [η] (dL / g) was measured using the 3D-SEC method described above; SCB was dimensional (CH3# / 1000C) and determined using FTIR as described above; M v The viscosity-average molar mass (g / mol) is determined using 3D-SEC as described above, and A is a dimensionless constant that depends on the α-olefin in the ethylene / α-olefin copolymer sample; specifically, A is 2.1626, 1.9772, or 1.1398 for 1-octene, 1-hexene, and 1-butene α-olefins, respectively. In the case of ethylene homopolymers, no correction for the Mark-Houwink constant is required, i.e., SCB is zero.

[0293] "Linear" ethylene copolymers (or linear ethylene homopolymers) that do not contain LCB or contain undetectable levels of LCB fall on the reference line defined by Eq.(3).

[0294] Log(IV c ) = 0.2100 × Log(ZSV) c -0.7879 Eq.(3)

[0295] LCBF calculation is based on the horizontal displacement (S) of the self-linear reference line. h ) and vertical displacement (S v ), as defined by the following equation:

[0296] S h =Log(ZSV) c -4.7619×Log(IV) c -3.7519 Eq.(4)

[0297] S v =0.2100×Log(ZSV) c )-Log(IV c )-0.7879 Eq.(5).

[0298] In Eq.(4) and Eq.(5), ZSV with dimensions of poise and dL / g are required. c and IV c Horizontal displacement (S) h ) is ZSV c At constant intrinsic viscosity (IV) c The displacement under zero shear viscosity (ZSV of the test sample) becomes clear if the Log function is removed; that is, the displacement under zero shear viscosity (ZSV of the test sample) represents the displacement under zero shear viscosity. c Compared to having the same IV c ZSV of linear ethylene copolymers (or linear ethylene homopolymers) c The ratio of horizontal displacement (S). h The vertical displacement (S) is dimensionless. v ) is IV c At constant zero shear viscosity (ZSV) c The displacement under the condition of ) is obvious in physical terms if the Log function is removed, that is, the displacement of two intrinsic viscosities (with the same ZSV) is related to the displacement of two intrinsic viscosities (with the same ZSV). c IV of linear ethylene copolymers (or linear ethylene homopolymers) c IV relative to the test sample c The ratio of vertical displacement (S) to vertical displacement (S). v () is dimensionless.

[0299] The dimensionless long chain branching factor (LCBF) is defined by Eq.(6):

[0300]

[0301] In one embodiment of this disclosure, an ethylene polymer having LCB (e.g., a polyethylene composition) is characterized by an LCBF ≥ 0.0010 (dimensionless); conversely, an ethylene polymer without LCB (or with undetectable LCB) is characterized by an LCBF < 0.0010 (dimensionless).

[0302] Hexane extract

[0303] Hexane extractables are determined in accordance with Sections (c) 3.1 and 3.2 of 21 CFR 177.1520 of the Federal Registration Code, wherein the amount of hexane extractables in the sample is determined by gravimetric analysis.

[0304] Membrane optics

[0305] The optical properties of the film (for both unstretched multilayer precursor films and stretched multilayer films) are measured as follows: haze, ASTM D1003-13 (November 15, 2013); and gloss 45, ASTM D2457-13 (April 1, 2013).

[0306] Elmendorf membrane tear

[0307] The tear properties of the film (both unstretched multilayer precursor films and stretched multilayer films) are determined according to ASTM D1922-09 (May 1, 2009); the equivalent term for tear is "Elmendorf tear". Film tear is measured in both the machine direction (MD) and transverse direction (TD) of the blown film.

[0308] Membrane mechanical properties

[0309] Machine-direction and transverse (MD and TD) tensile tests are typically performed according to ASTM D882 (ASTM D882-10 and ASTM D882-12). The specimen width for tensile property measurements is 1.0 inch. Tensile speed is 1 mm / min to 5% strain, then increased to 100 mm / min until fracture. The clamp spacing is 100 mm. The mechanical properties measured are tensile fracture stress (reported in MPa), yield strain (%), yield stress (MPa), fracture strain (%), and fracture stress (MPa). 1% and 2% secant modulus (MPa) are measured using 1.0 inch wide specimens, 2-inch clamp spacing, and a test speed of 1.0 inch / min.

[0310] Membrane thermal shrinkage rate (%)

[0311] Using a 10×10cm membrane sample, the shrinkage rate of the membrane was measured by placing the sample in a 120°C oven in air for 5 minutes. The relative reduction in length of the heated membrane in both the machine direction and transverse direction compared to the original membrane is reported as the shrinkage rate percentage. (%) Shrinkage rate = (L) 初始 -L 最终 ) / L 初始 L 初始 and L 最终 It refers to the length before and after heat treatment.

[0312] Membrane puncture resistance

[0313] According to ASTM D5748-95, membrane puncture resistance (J / mm) was measured for both unstretched precursor multilayer membranes and stretched multilayer membranes. Membrane displacement relative to force (lb) was recorded, and the maximum force was reported as the puncture force (lb) at breakage according to ASTM D5748-95.

[0314] film thickness

[0315] The film thickness of unstretched precursor multilayer films and stretched multilayer films is measured according to ASTM D 6988-13.

[0316] Preparation of polyethylene compositions

[0317] Polyethylene compositions are prepared using a mixed dual-catalyst system via a “tandem” two-reactor solution polymerization method. As a result, the polyethylene composition comprises a first ethylene copolymer prepared with a single-site catalyst and a second ethylene copolymer prepared with a multi-site catalyst. The “tandem” two-reactor solution-phase polymerization method (including a reactor employing a mixed dual-catalyst) has been described in U.S. Patent Application Publication No. 2018 / 0305531. Essentially, in the “tandem” two-reactor system, the effluent stream from the first polymerization reactor (R1) flows directly into the second polymerization reactor (R2). R1 ​​is operated at a pressure of approximately 14 MPa to approximately 18 MPa; while R2 operates at a lower pressure to facilitate continuous flow from R1 to R2. Both R1 and R2 are continuously stirred reactors (CSTRs) and are stirred to provide conditions for thorough mixing of the reactor contents. The process is carried out continuously by feeding fresh process solvent, ethylene, 1-octene, and hydrogen into the reactors and removing the products. Note that in the inventive examples, fresh 1-octene is fed into both the first reactor R1 and the second reactor R2 (in fact, for inventive examples 1-3, more 1-octene is fed into the second reactor than into the first reactor). Methylpentane is used as the method solvent (a commercial blend of methylpentane isomers). The first CSTR reactor (R1) has a volume of 3.2 gallons (12 L), and the second CSTR reactor (R2) has a volume of 5.8 gallons (22 L). The monomer (ethylene) and comonomer (1-octene) are purified using conventional feed preparation systems (such as contact with various absorbent media to remove impurities such as water, oxygen, and polar contaminants) before being added to the reactors. The reactor feed is pumped into the reactors at the ratios shown in Table 1. The average residence time in the reactors is calculated by dividing the average flow rate by the reactor volume and is primarily affected by the amount of solvent flowing through each reactor and the total amount of solvent flowing through the solution method.

[0318] In the first reactor R1, the following unit-site catalyst components were used to prepare the first ethylene copolymer: diphenylmethylene(cyclopentadienyl)(2,7-di-tert-butylfluorenyl)dimethylhafnium [(2,7-tBu2Flu)Ph2C(Cp)HfMe2]; methylaluminoxane (MMAO-07); triphenylmethyl tetratetra(pentafluorophenyl)borate (triphenylmethyl borate); and 2,6-di-tert-butyl-4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07) and 2,6-di-tert-butyl-4-ethylphenol were premixed online and then combined with diphenylmethylene(cyclopentadienyl)(2,7-di-tert-butylfluorenyl)dimethylhafnium and triphenylmethyl tetratetra(pentafluorophenyl)borate before being fed into the polymerization reactor (R1). The efficiency of the unit-site catalyst formulation was optimized by adjusting the molar ratio of the catalyst components and the catalyst inlet temperature of R1.

[0319] The second ethylene copolymer was prepared in a second reactor (R2) using the following Ziegler-Natta (ZN) catalyst components: butyl ethyl magnesium; tert-butyl chloride; titanium tetrachloride; diethylaluminum ethoxide; and triethylaluminum. Methylpentane was used as the solvent for the catalyst components, and the online Ziegler-Natta catalyst formulation was prepared using the following steps and then injected into the second reactor (R2). In step one, a solution of triethylaluminum and butyl ethyl magnesium (Mg:Al = 20, mol:mol) was combined with a solution of tert-butyl chloride and allowed to react for approximately 30 seconds to produce a MgCl2 support. In step two, a titanium tetrachloride solution was added to the mixture formed in step one and allowed to react for approximately 14 seconds before being injected into the second reactor (R2). The online Ziegler-Natta catalyst was activated in the reactor by injecting the diethylaluminum ethoxide solution into R2. The amount of titanium tetrachloride added to the reactor is shown in Table 1. The efficiency of the online Ziegler-Natta catalyst formulation was optimized by adjusting the molar ratio of the catalyst components.

[0320] The polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the exit stream of the second reactor. The catalyst deactivator used was octanoic acid (caprylic acid), available from P&G Chemicals, Cincinnati, OH, USA. The catalyst deactivator was added such that the molar amount of the added fatty acid was 50% of the total molar amount of hafnium, titanium, and aluminum added to the polymerization process; specifically, the molar amount of added octanoic acid = 0.5 × (molar amount of hafnium + molar amount of titanium + molar amount of aluminum).

[0321] A two-stage devolatification process is employed to recover ethylene interpolymer products from the process solvent, using two gas / liquid separators, with a second bottom stream (from a second V / L separator) passing through a gear pump / granulator assembly. In the continuous solution process, DHT-4V (hydrotalcite), supplied by Kyowa Chemical Industry Co., Ltd., Tokyo, Japan, is used as a passivating agent or deacidifying agent. A slurry of DHT-4V in the process solvent is added before the first V / L separator.

[0322] Prior to granulation, approximately 500 ppm of a polyethylene composition by weight is added. 1076 (the main antioxidant) and approximately 500 ppm 168 (minor antioxidant) is used to stabilize the polyethylene composition. The antioxidant is dissolved in the method solvent and added between the first V / L separator and the second V / L separator.

[0323] Table 1 shows the reactor conditions used to prepare the polyethylene compositions of the present invention (Examples 1-3) and the reactor conditions used to prepare the comparative polyethylene compositions (Comparative Example 4). Table 1 includes method parameters such as the ethylene and 1-octene split between reactors (R1 and R2), reactor temperature, ethylene conversion, etc. As can be seen from the data provided in Table 1, the so-called "octene split" used to prepare the polyethylene compositions of the present invention involves feeding fresh 1-octene into both reactors, with more 1-octene fed into the second reactor R2. This is the opposite of the polymerization conditions used to prepare the comparative polyethylene compositions (Comparative Example 4), in which only 1-octene is fed into the first reactor (Note: Although the comonomer is not directly fed into the downstream second reactor R2, when Comparative Example 4 is prepared, due to the large amount of unreacted 1-octene flowing from the first reactor to the second reactor, the unreacted 1-octene copolymerizes with ethylene in the second reactor, still forming an ethylene copolymer in the second reactor). For Examples 1-3 of the invention, the hydrogen level and temperature of the first reactor R1 are optimized to produce a first ethylene copolymer with a weight-average molecular weight Mw greater than about 170,000 g / mol, while the hydrogen level and temperature of the second reactor R2 are optimized to produce a second ethylene copolymer with a weight-average molecular weight Mw less than about 50,000 g / mol.

[0324] The properties of the polyethylene compositions of Invention Examples 1-3 produced according to this disclosure are provided in Table 2. Table 2 also includes data for Comparative Example 4 of the polyethylene compositions.

[0325] Table 1

[0326] Aggregation conditions

[0327]

[0328]

[0329]

[0330] Table 2

[0331] Polymer properties

[0332]

[0333]

[0334] Modeling of polyethylene compositions

[0335] For multi-component polyethylene compositions, in this paper (see results provided in Table 3), the M values ​​of the first and second ethylene copolymers were calculated using reactor model simulation with input conditions applicable to actual pilot-scale polymerization operation conditions. w M n and M w / M n (For reference on relevant reactor modeling methods, see “Copolymerization”, A. Hamielec, J. MacGregor and A. Penlidis, Comprehensive Polymer Science and Supplements, Vol. 3, Chapter 2, p. 17, Elsevier, 1996, and “Copolymerization of Olefins in a Series of Continuous Stirred-Tank Slurry-Reactors using Heterogeneous Ziegler-Natta and Metallocene Catalysts. I. General Dynamic Mathematical Model”, JBP Soares and A. E. Hamielec, Polymer Reaction Engineering, 4(2&3), p. 153, 1996).

[0336] The model employs the flow rates, temperatures (in each reactor), and monomer conversion rates (in each reactor) of several reactive substances entering each reactor (e.g., catalyst, monomers such as ethylene, comonomers such as 1-octene, hydrogen, and solvent), and calculates polymer properties (for the polymers prepared in each reactor, i.e., the first and second ethylene copolymers) using an end-kinetic model for a continuous stirred tank reactor (CSTR) connected in series. The “end-kinetic model” assumes that the kinetics depend on the monomer units within the polymer chain where the active catalyst site is located (see “Copolymerization,” A. Hamielec, J. MacGregor, and A. Penlidis, Comprehensive Polymer Science and Supplements, Vol. 3, Chapter 2, p. 17, Elsevier, 1996). In this model, it is assumed that the copolymer chains have reasonably large molecular weights to ensure that the statistics on monomer / comonomer unit insertion at the center of the active catalyst are valid, and that the monomer / comonomer consumed in pathways other than growth are negligible. This is referred to as the “long-chain” approximation.

[0337] The end-kinetic model of polymerization includes reaction rate equations for activation, initiation, propagation, chain transfer, and deactivation pathways. This model solves for steady-state conservation equations (e.g., total mass balance and thermal balance) of the reaction fluid containing the reactive substances identified above.

[0338] The overall mass balance of a typical continuous stirred tank reactor (CSTR) with a given number of inlets and outlets is given by the following equation:

[0339] (1)

[0340] in This represents the quality flow rate of a single logistics item; the subscript 'i' indicates inbound and outbound logistics.

[0341] Equation (1) can be further expanded to show individual substances and reactions:

[0342] (2)

[0343] Where M i x is the average molar quantity at the fluid inlet or outlet (i). ij ρ is the mass fraction of substance j in logistics i. mix R is the molar density of the mixture in the reactor, V is the reactor volume, and R is the reactor volume. j It is the reaction rate of substance j, and its unit is kmol / m 3 s.

[0344] For an adiabatic reactor, the overall heat balance is solved, and the result is given by the following equation:

[0345] (3)

[0346] in, It is the mass flow rate of logistics i (inlet or outlet), ΔH i It is the enthalpy difference of logistics i relative to the reference state, q Rx It is the heat released by the reaction, and V is the reactor volume. It is a power input (i.e., a stirrer). It is heat input / loss.

[0347] The catalyst concentration input to each reactor is adjusted to match the experimentally determined ethylene conversion and reactor temperature values ​​in order to solve the equations of the kinetic model (e.g., growth rate, heat balance, and mass balance).

[0348] The H2 concentration input to each reactor can be adjusted in the same way so that the calculated molecular weight distribution of the polymers prepared in both reactors (and therefore the molecular weight of the polymers prepared in each reactor) matches the experimentally observed molecular weight distribution.

[0349] The weight fractions wt1 and wt2 of the materials prepared in each reactor R1 and R2 are determined by the known mass flow rates of the monomers and comonomers entering each reactor and the known conversion rates of the monomers and comonomers in each reactor calculated based on kinetic reactions.

[0350] Degree of polymerization (dp) of a polymerization reaction n The rate is given by the ratio of the chain growth reaction rate to the chain transfer / termination reaction rate: (4)

[0352]

[0353] Where k p11 It is the growth rate constant for adding monomer 1 to the growing polymer chain ending with monomer 1, [m1] is the molar concentration of monomer 1 (ethylene) in the reactor, and k is the growth rate constant for adding monomer 1 to the growing polymer chain ending with monomer 1. p12 k is the growth rate constant when monomer 2 is added to a growing polymer chain ending with monomer 1. p21 [m2] is the growth rate constant for the addition of monomer 1 to the growing polymer chain ending with monomer 2, [m2] is the molar concentration of monomer 2 (1-octene) in the reactor, and k is the growth rate constant for the addition of monomer 1 to the growing polymer chain ending with monomer 2. p22 k is the growth rate constant when monomer 2 is added to the growing polymer chain ending with monomer 2. tm11 For a growing chain ending with monomer 1, k is the termination rate constant for the chain to transition to monomer 1. tm12For a growing chain ending with monomer 1, k is the termination rate constant for the chain transitioning to monomer 2. tm21 For a growing chain ending with monomer 2, k is the termination rate constant for the chain to transition to monomer 1. tm22 For a growing chain ending with monomer 2, k is the termination rate constant for the chain transitioning to monomer 2. ts1 For a chain ending with monomer 1, k is the rate constant for spontaneous chain termination. ts2 For a chain ending with monomer 2, k is the rate constant for spontaneous chain termination. tH1 k is the rate constant for chain termination by hydrogen, where the chain ends with monomer 1. tH2 φ1 is the rate constant for chain termination by hydrogen for chains ending with monomer 2. φ1 and φ2 are the fractions of catalyst sites occupied by chains ending with monomer 1 or monomer 2, respectively.

[0354] The number-average molecular weight (Mn) of a polymer is determined by the degree of polymerization and the molecular weight of the monomer units. Based on the number-average molecular weight of the polymer in a given reactor, and assuming a Flory-Schulz distribution of the catalyst at a single point, the following relationship is used to determine the molecular weight distribution of the polymer.

[0355] (5) w(n)=nτ 2 e -τn

[0356] Where n is the number of monomer units in the polymer chain, w(n) is the weight fraction of the polymer chain with chain length n, and τ is calculated using the following equation:

[0357]

[0358] Where dp n It is the degree of aggregation, R p It is the growth rate, and R t It is the termination rate.

[0359] The Flory-Schulz distribution can be transformed into a commonly used log-scaled GPC trace by applying the following equation:

[0360] (6)

[0361] in It is the differential weight fraction of a polymer with chain length n (n = MW / 28, where 28 is the molecular weight of the polymer segment corresponding to the C2H4 unit) and dp n It refers to the degree of aggregation.

[0362] Assuming the Flory-Schultz model, the different moments of the molecular weight distribution can be calculated using the following equation:

[0363] μ i =∫0 ∞ n i W(n)dn

[0364] therefore,

[0365] μ0 = 1,

[0366] μ1=dp n ,as well as

[0367] μ2=2dp n 2 ;

[0368] therefore,

[0369]

[0370]

[0371] Among them Mw 单体 It is the molecular weight of the polymer segment corresponding to the C2H4 unit of the monomer.

[0372] Alternatively, when using a Ziegler-Natta catalyst, the molecular weight distribution of the polymer prepared by the Ziegler-Natta catalyst in a given reactor can be modeled as described above, but using the sum of four such unit-point catalyst sites, assuming each site has a Flory-Schultz distribution. When considering the kinetics of the Ziegler-Natta catalyst method model, the total amount of Ziegler-Natta catalyst component fed into the reactor is known, and it is assumed that each of the four active catalyst sites modeled has the same weight fraction, but where each site has its own kinetics.

[0373] Finally, when the single-site catalyst produces long chain branches, the molecular weight distribution of the polymer is determined using the following relationship (see “Polyolefins with Long Chain Branches Made with Single-Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure”, JBP Soares, Macromolecular Materials and Engineering, Vol. 289, No. 1, pp. 70-87, Wiley-VCH, 2004 and “Polyolefin Reaction Engineering”, JBP Soares and TFLMcKenna Wiley-VCH, 2012).

[0374]

[0375] Where n is the number of monomer units in the polymer chain, w(n) is the weight fraction of the polymer chain with chain length n, and τ B And α are calculated using the following equation:

[0376]

[0377]

[0378] in It is the degree of aggregation, R p It is the growth rate, R t It is the termination rate, and R LCB The long chain branching rate is calculated using the following equation:

[0379] R LCB =k p13 φ1[m3]

[0380] Where k p13 [m3] is the growth rate constant for adding monomer 3 (the macromonomer formed in the reactor) to the growing polymer chain ending with monomer 1, and [m3] is the molar concentration of the macromonomer in the reactor.

[0381] The weight distribution can be transformed into a commonly used logarithmic scale GPC trace by applying the following equation:

[0382] (7)

[0383] in It is the differential weight fraction of a polymer with chain length n (n = MW / 28, where 28 is the molecular weight of the polymer segment corresponding to the C2H4 unit).

[0384] From the weight distribution, the different moments of the molecular weight distribution can be calculated using the following equation:

[0385]

[0386]

[0387]

[0388] in It is the degree of aggregation, and α is calculated as above.

[0389] Branch frequency

[0390] The short-chain branching frequency (SCB2 / 1000 carbon) of the second ethylene copolymer was calculated using the following equation based on the kinetic equation and comonomer consumption:

[0391]

[0392] Where R BF The rate of short-chain branch formation is calculated using the following equation:

[0393] R BF =k p21 φ2[m1]+k p22 φ2[m2]+k tm12 φ1[m2]+k tm22 φ2[m2]

[0394] The short-chain branching frequency of the first ethylene copolymer was estimated using the following equation:

[0395] SCB1=(SCB-w2SCB2) / w1

[0396] SCB1, SCB2, and SCB represent the number of short-chain branches per 1000 carbons in the first ethylene copolymer, the second ethylene copolymer (as determined above), and the experimentally determined short-chain branching frequency of the total polyethylene composition (i.e., as determined by FTIR analysis), respectively, and w1 and w2 represent the corresponding weight fractions of the first and second ethylene copolymer components.

[0397] Melt index

[0398] The melt index I2 of the first and second ethylene copolymers is calculated based on the following equation:

[0399]

[0400] density

[0401] The density of the second ethylene copolymer prepared in R2 was calculated using the following equation with the estimated SCB2, Mn, and Mw of the second ethylene copolymer as input:

[0402]

[0403] Then, the density of the first ethylene copolymer prepared in R1 was estimated using the following equation:

[0404] ρ1=(ρ-w2ρ2) / w1

[0405] Wherein ρ1, ρ2 and ρ are the densities of the first ethylene copolymer, the second ethylene copolymer (as measured above), and the experimentally determined total density of the polyethylene composition (i.e., determined according to ASTM D792-13), respectively, and w1 and w2 represent the corresponding weight fractions of the first and second ethylene copolymer components.

[0406] Table 3

[0407] Polyethylene composition component properties

[0408]

[0409]

[0410] Figure 1 The following are shown: the polyethylene compositions of this disclosure (Examples 1-3 of the invention) and the comparative polyethylene composition (Comparative Example 4) have bimodal GPC characteristic curves.

[0411] Figure 2 The polyethylene compositions of this disclosure (Examples 1-3 of the invention) are shown to have bimodal GPC characteristic curves and a relatively constant or slightly increasing amount of comonomers (as indicated by the short chain branching content, SCB / 1000 main chain carbon atoms) with increasing molecular weight. Figure 2 The comparative resin Comparative Example 4 is also shown to have a bimodal GPC characteristic curve and a significantly increased comonomer content with increasing molecular weight.

[0412] Figure 3The following figures illustrate the polyethylene compositions of this disclosure (Examples 1-3) eluted at temperatures above 90°C in CTREF analysis. Indeed, for Examples 1-3, the CTREF characteristic curves show a large elution fraction dominating with one or two peaks, where over 50% by weight of the polymer material eluted at temperatures between 90°C and 98°C. In contrast, the CTREF characteristic curve obtained for Comparative Example 4 shows two well-separated, distinct elution peaks, where a significant amount of polymer material eluted below 90°C. The different CTREF characteristic curves observed for the polyethylene compositions of the present invention (Examples 1-3) and the comparative polyethylene composition (Comparative Example 4) are consistent with the relatively flat (or uniform) and relatively inverted comonomer distributions observed for the polyethylene compositions of the present invention and the comparative polyethylene compositions, respectively.

[0413] like Figure 4 As shown, the melting point temperatures of the polyethylene compositions prepared according to this disclosure (Examples 1-3) are slightly lower than those obtained for the comparative polyethylene compositions (Comparative Example 4). Without being bound by theory, a lower polymer melting point may be beneficial for preparing BOPE film structures during the biaxial stretching process; a lower melting point indicates the presence of more amorphous material in the polyethylene composition, which may contribute to earlier softening of the sheet or film (prepared from the polymer composition) during the stretching process (i.e., during MD and / or TD orientation), thereby improving the stretching process condition window.

[0414] Figure 5 This demonstrates that the polyethylene compositions prepared according to this disclosure in Examples 1-3 of the Invention have good apparent shear viscosity and good shear thinning behavior (e.g., apparent shear viscosity decreases with increasing shear or deformation rate). Without being bound by theory, good shear thinning behavior can provide high productivity during the extrusion process for preparing BOPE films in a tenter frame method.

[0415] A. Preparation of unstretched membranes (or "base membranes")

[0416] A single-layer sheet is extruded at a rate of 20 kg / hr through a 270 mm wide casting die with a 1.5 mm die gap. The sheet is then cast onto a cooling roller. An air knife and edge pinners are used to pin the sheet to the casting roller. The target sheet size is 700 microns. For convenience, this unstretched single-layer sheet is sometimes referred to as the "base film".

[0417] Using the above conditions, monolayer base films were prepared using Invention Examples 1-3 and Comparative Example 4 to produce base films or sheets.

[0418] Then, using the procedures described in Part B below, an attempt was made to prepare a biaxially oriented polyethylene (BOPE) film from each of these base films.

[0419] Part B: Preparation of BOPE film - simultaneous stretching

[0420] Biaxially oriented polyethylene (BOPE) films were prepared in a laboratory (or pilot-scale) biaxial stretching machine: a KARO 5.0 biaxial stretching unit from Brückner, Germany. BOPE films were prepared from square samples approximately 10 cm × 10 cm in size, cut from a monolayer base film prepared by cast co-extrusion as described above. After preheating to the set temperature in an oven chamber for 120 seconds, the base film samples were simultaneously biaxially stretched (i.e., in both the machine direction and transverse direction) at a stretching rate of 100%–300% / second. Once stretched, the BOPE films were removed from the clamping device and allowed to cool. Machine orientation (MDO) and transverse orientation (TDO) were performed at temperatures ranging from 120°C to 125°C, with a stretch (or draw) ratio of 5.5 to 8:1. The results are provided in Table 4.

[0421] If a base film can be successfully stretched using a KARO 5.0 biaxial stretching machine from Brückner, then the polyethylene composition used to prepare the film is said herein to have "passed" the BOPE stretching process. More generally, a polyethylene composition is said to have "passed" the BOPE stretching process if a) a film can be formed without tearing or forming pores, and b) the material exhibits strain hardening characteristics in the tensile force measured during the orientation process. Figure 6 and Figure 7 As shown, it respectively shows the N / mm 2 The change in MD or TD stress as the MD or TD stretch ratio increases: the polyethylene composition that has "passed" the BOPE stretching process exhibits an initial rapid increase in stress until the yield point, followed by a slightly slower increase in stress (strain softening behavior) and then a steady increase in stress (strain hardening behavior).

[0422] If the membrane cannot be successfully stretched in one or both directions, including the machine direction and the transverse direction, if the membrane shows signs of tearing or other obvious breakage, or if the polyethylene composition being tested exhibits little or no strain hardening behavior, the polyethylene composition used to prepare the membrane will be described herein as a “failure” of the BOPE stretching process.

[0423] Table 4

[0424] BOPE membrane production

[0425]

[0426] Table 5

[0427] BOPE membrane properties

[0428]

[0429] As shown in Table 4, the polyethylene compositions prepared according to this disclosure (Examples 1-3) can each be successfully used to form BOPE films at various MD and TD orientation ratios, while the comparative polyethylene composition (Comparative Example 4) cannot. The data in Table 5 also show that the BOPE films prepared from the polyethylene compositions of this disclosure (Examples 1-3) have good optical properties, with a haze value of less than about 10%.

[0430] Those skilled in the art will recognize from the data provided in Tables 2 and 3 that a high density (e.g., greater than about 0.940 g / cm³) is desirable. 3 The polyethylene compositions of the present invention (Examples 1-3) further possess the following characteristics: i) a significant amount of long-chain branching (e.g., LCBF > 0.0100); ii) a relatively constant comonomer content with increasing molecular weight (e.g., an SCB1 / SCB2 ratio greater than about 1.0 but less than about 3.0); iii) a relatively broad molecular weight distribution (e.g., Mw / Mn greater than about 3.5); iv) a relatively high melt flow ratio (e.g., I 21 / I2 greater than about 40); and v) a relatively large amount of polymer material was eluted at temperatures above about 90°C in CTREF analysis.

[0431] Based on the data provided in Tables 2-5, those skilled in the art will recognize that the polyethylene compositions of this disclosure are suitable for methods of preparing BOPE films and multilayer BOPE film structures.

[0432] The non-restrictive embodiments disclosed herein include the following:

[0433] Implementation Scheme A. A polyethylene composition comprising:

[0434] (i) 5% to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol; and

[0435] (ii) 95% to 50% by weight of a second ethylene copolymer;

[0436] The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer;

[0437] The ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is 0.8 to 3.5.

[0438] The polyethylene composition wherein the density is 0.941 to 0.962 g / cm³. 3 Melt index I2 is 0.5 to 5.0 g / 10 min; melt flow ratio I 21 / I2≥40; Z-mean molecular weight distribution Mz / Mw≥2.5; comonomer distribution width index CDBI 50 >50wt%; Long-chain branching factor (LCBF) >0.0010;

[0439] In the temperature-elution fractionation (CTREF) analysis, the polyethylene composition has more than 70% by weight of material eluted at a temperature greater than 90°C.

[0440] Implementation Scheme B. The polyethylene composition according to Implementation Scheme A, wherein, in temperature elution fractionation (CTREF) analysis, the polyethylene composition has more than 50% by weight of material eluted at a temperature of 90°C to 98°C.

[0441] Implementation Scheme C. The polyethylene composition according to Implementation Scheme A or B has a molecular weight distribution Mw / Mn of 3.5 to 6.5.

[0442] Implementation Scheme D. The polyethylene composition according to Implementation Scheme A, B or C has a Z-average molecular weight Mz ≥ 250,000 g / mol.

[0443] Implementation Scheme E. The polyethylene composition according to Implementation Scheme A, B, C or D, having a comonomer distribution width index CDBI. 50 >65wt%.

[0444] Implementation Scheme F. The polyethylene composition according to Implementation Scheme A, B, C, D or E, wherein the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer is 0.8 to 3.0.

[0445] Implementation scheme G. The polyethylene composition according to implementation schemes A, B, C, D or E, wherein the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer is 1.0 to 3.0.

[0446] Implementation Scheme H. A polyethylene composition according to Implementation Scheme A, B, C, D, E, F or G, wherein the first ethylene copolymer has <7.5 short chain branches / 1000 carbon atoms (SCB1 / 1000C).

[0447] Implementation Scheme I. A polyethylene composition according to Implementation Scheme A, B, C, D, E, F, G or H, wherein the second ethylene copolymer has <3.0 short chain branches / 1000 carbon atoms (SCB2 / 1000C).

[0448] Implementation Scheme J. The polyethylene composition according to Implementation Scheme A, B, C, D, E, F, G, H or I, wherein the first ethylene copolymer has a content of 0.930 to 0.955 g / cm³. 3 The density.

[0449] Implementation Scheme K. The polyethylene composition according to Implementation Scheme A, B, C, D, E, F, G, H, I or J, wherein the second ethylene copolymer has a content of 0.935 to 0.960 g / cm³. 3 The density.

[0450] Implementation Scheme L. A polyethylene composition according to Implementation Scheme A, B, C, D, E, F, G, H, I, J or K, wherein the first ethylene copolymer has a melt index I2 of <0.5 g / 10 min.

[0451] Implementation scheme M. The polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K or L, wherein the second ethylene copolymer has a melt index I2 of >10.0 g / 10 min.

[0452] Implementation scheme N. The polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L or M, wherein the first ethylene copolymer has a molecular weight distribution Mw / Mn of 1.7 to 2.3.

[0453] Implementation scheme O. A polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M or N, wherein the second ethylene has a molecular weight distribution Mw / Mn of ≥2.3.

[0454] Implementation scheme P. The polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M, N or O, having a content of 0.942 g / cm³. 3 Up to 0.954 g / cm 3 The density.

[0455] Implementation Scheme Q. The polyethylene composition according to Implementation Scheme A, B, C, D, E, F, G, H, I, J, K, L, M, N, O or P, having a melt index I2 of 0.5 to 2.5 g / 10 min.

[0456] Implementation scheme R. A polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P or Q, having a melt flow ratio ≥45. 21 / I2.

[0457] Implementation S. The polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P or Q, having a melt flow ratio of 45 to 100. 21 / I2.

[0458] Implementation scheme T. The polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R or S, having a Z-average molecular weight distribution Mz / Mw of 2.5 to 4.5.

[0459] Implementation scheme U. A polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R or S, wherein the polyethylene composition has a Z-average molecular weight distribution Mz / Mw > 2.8.

[0460] Implementation scheme V. A polyethylene composition according to implementation schemes A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T or U, having a Z-average molecular weight of 250,000 to 500,000 g / mol.

[0461] Implementation scheme W. A polyethylene composition according to implementation schemes 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 has a hafnium residue present at a concentration of at least 0.05 ppm based on the weight of the polyethylene composition.

[0462] Implementation Scheme X. A polyethylene composition according to Implementation Scheme 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 polyethylene composition has a long chain branching factor (LCBF) > 0.0050.

[0463] Implementation scheme Y. A polyethylene composition according to implementation schemes 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 polyethylene composition has a long chain branching factor (LCBF) > 0.0100.

[0464] Implementation Scheme Z. A polyethylene composition according to Implementation Scheme 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 first ethylene copolymer is prepared using a single-point catalyst.

[0465] Implementation scheme AA. The polyethylene composition according to implementation schemes 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 or Z, wherein the second ethylene copolymer is prepared using a single-point catalyst or a Ziegler-Natta catalyst.

[0466] Implementation Scheme BB. A biaxially oriented polyethylene film comprising a polyethylene composition, said polyethylene composition comprising:

[0467] (i) 5% to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol; and

[0468] (ii) 95% to 50% by weight of a second ethylene copolymer;

[0469] The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer;

[0470] The ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is 0.8 to 3.5.

[0471] The polyethylene composition wherein the density is 0.941 to 0.962 g / cm³. 3 Melt index I2 is 0.5 to 5.0 g / 10 min; melt flow ratio I 21 / I2≥40; Z-mean molecular weight distribution Mz / Mw≥2.5; comonomer distribution width index CDBI 50 >50wt%; Long-chain branching factor (LCBF) >0.0010;

[0472] In the temperature-elution fractionation (CTREF) analysis, the polyethylene composition has more than 70% by weight of material eluted at a temperature greater than 90°C.

[0473] While certain embodiments have been described and illustrated, it should be understood that changes and modifications may be made therein in accordance with common art without departing from the broader aspects of the present technology as defined in the appended claims.

[0474] The embodiments described herein can be practiced appropriately in the absence of any one or more elements or limitations not specifically disclosed herein. Therefore, terms such as “comprising,” “including,” and “containing” should be interpreted broadly and without limitation. Furthermore, the terms and expressions used herein have been used as descriptive and non-limiting terms, and their use is not intended to exclude any equivalents of the shown and described features or portions thereof, but rather to allow for various modifications within the scope of the claimed technology. Additionally, the phrase “consistently composed of” will be understood to include those specifically listed elements and those additional elements that do not materially affect the essential and novel features of the claimed technology. The phrase “consisting of” excludes any unspecified elements.

[0475] This disclosure is not limited to the specific embodiments described herein. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from its spirit and scope. Those skilled in the art will understand from the foregoing description functionally equivalent methods and compositions to those listed herein, in addition to those listed herein. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the claims of the appended claims and the full scope of their equivalents. It should be understood that this disclosure is not limited to specific methods, reagents, compounds, compositions, or biological systems, which are of course subject to change. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be restrictive.

[0476] Furthermore, where features or aspects of this disclosure are described in accordance with the Markush Group, those skilled in the art will recognize that this disclosure is therefore also described in accordance with any individual member or subgroup of the Markush Group.

[0477] As those skilled in the art will understand, for any and all purposes, particularly in providing a written description, all scopes disclosed herein also encompass any and all possible subscopes and combinations thereof. Any listed scope can be readily considered sufficiently descriptive and capable of being decomposed into at least two, three, four, five, ten, etc., equal parts. As a non-limiting example, each scope discussed herein can be readily decomposed into a lower third, a middle third, and an upper third, etc. Likewise, as those skilled in the art will understand, terms such as “at most,” “at least,” “greater than,” “less than,” etc., include the listed numbers and relate to scopes that can subsequently be decomposed into subscopes as discussed above. Finally, as those skilled in the art should understand, a scope includes each individual member.

[0478] All publications, patent applications, granted patents and other documents mentioned in this specification are incorporated herein by reference as if each individual publication, patent application, granted patent or other document were specifically and individually incorporated by reference in its entirety. Definitions contained in the text incorporated by reference are excluded to the extent that they conflict with definitions in this disclosure.

[0479] Other embodiments are set forth in the appended claims.

[0480] Industrial applicability

[0481] This disclosure relates to polyethylene compositions that can be used to form biaxially oriented films. Biaxially oriented polyethylene films can be used in a variety of packaging applications, including “all-polyethylene packaging” that can promote recycling.

Claims

1. A polyethylene composition comprising: (i) 5 to 50 wt% of a first ethylene copolymer having a weight average molecular weight Mw of 170,000 to 470,000 g / mol; and (ii) 95 to 50 wt% of a second ethylene copolymer; wherein the first ethylene copolymer has a higher weight average molecular weight Mw than the second ethylene copolymer; wherein the ratio of the number of short chain branches per thousand carbon atoms (SCB1) in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms (SCB2) in the second ethylene copolymer (SCB1 / SCB2) is 0.8 to 3.5; wherein the polyethylene composition has a density of 0.941 to 0.962 g / cm 3 ; a melt index, I2, of 0.5 to 5.0 g / 10 min; a melt flow ratio, I 21 / I2, of > 40; a Z-average molecular weight distribution, Mz / Mw, of > 2.5; a comonomer distribution breadth index, CDBI 50 > 50 wt%; a long chain branching factor, LCBF, of > 0.0010; wherein the polyethylene composition has greater than 70 wt% of material eluting at a temperature greater than 90°C in a temperature rising elution fractionation (CTREF) analysis.

2. The polyethylene composition according to claim 1, wherein, the polyethylene composition has greater than 50 wt% of material eluting at a temperature from 90°C to 98°C in a temperature rising elution fractionation (CTREF) analysis.

3. The polyethylene composition of claim 1 having a molecular weight distribution Mw / Mn of 3.5 to 6.

5.

4. The polyethylene composition of claim 1 having a Z average molecular weight Mz of > 250,000 g / mol.

5. The polyethylene composition of claim 1 having a comonomer distribution breadth index CDBI of > 65 wt% 50 .

6. The polyethylene composition of claim 1 wherein the ratio of the number of short chain branches per thousand carbon atoms (SCB1) in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms (SCB2) in the second ethylene copolymer (SCB1 / SCB2) is 0.8 to 3.

0.

7. The polyethylene composition of claim 1 wherein the ratio of the number of short chain branches per thousand carbon atoms (SCB1) in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms (SCB2) in the second ethylene copolymer (SCB1 / SCB2) is 1.0 to 3.

0.

8. The polyethylene composition of claim 1 wherein the first ethylene copolymer has < 7.5 short chain branches per 1000 carbon atoms (SCB1 / 1000C).

9. The polyethylene composition of claim 1 wherein the second ethylene copolymer has < 3.0 short chain branches per 1000 carbon atoms (SCB2 / 1000C).

10. The polyethylene composition of claim 1, wherein the first ethylene copolymer has a density of 0.930 to 0.955 g / cm 3 .

11. The polyethylene composition of claim 1, wherein the second ethylene copolymer has a density of 0.935 to 0.960 g / cm 3 .

12. The polyethylene composition of claim 1 wherein the first ethylene copolymer has a melt index I2 of < 0.5 g / 10 min.

13. The polyethylene composition of claim 1 wherein the second ethylene copolymer has a melt index I2 of > 10.0 g / 10 min.

14. The polyethylene composition of claim 1 wherein the first ethylene copolymer has a molecular weight distribution Mw / Mn of 1.7 to 2.

3.

15. The polyethylene composition of claim 1 wherein the second ethylene has a molecular weight distribution Mw / Mn of > 2.

3.

16. The polyethylene composition of claim 1, having a density of 0.942 g / cm 3 to 0.954 g / cm 3 3. The method of claim 1, wherein the first and second sets of instructions are executed in parallel.

17. The polyethylene composition of claim 1 having a melt index I2 of 0.5 to 2.5 g / 10 min.

18. The polyethylene composition of claim 1 having a melt flow ratio, I 21 / I2, of > 45.

19. The polyethylene composition of claim 1 having a melt flow ratio, I 21 / I2, of 45 to 100.

20. The polyethylene composition of claim 1 having a Z-average molecular weight distribution Mz / Mw of 2.5 to 4.

5.

21. The polyethylene composition of claim 1 wherein the polyethylene composition has a Z- average molecular weight distribution Mz / Mw of > 2.

8.

22. The polyethylene composition of claim 1 having a Z-average molecular weight of 250,000 to 500,000 g / mol.

23. The polyethylene composition of claim 1 wherein the polyethylene composition has hafnium residue present at least 0.05 ppm based on the weight of the polyethylene composition.

24. The polyethylene composition of claim 1 wherein the polyethylene composition has a long chain branching factor LCBF of > 0.0050.

25. The polyethylene composition of claim 1 wherein the polyethylene composition has a long chain branching factor LCBF of > 0.0100.

26. The polyethylene composition of claim 1 wherein the first ethylene copolymer is made with a single site catalyst.

27. The polyethylene composition of claim 1 wherein the second ethylene copolymer is made with a single site catalyst or a Ziegler-Natta catalyst.

28. A biaxially oriented polyethylene film comprising a polyethylene composition, the polyethylene composition comprising: (i) 5 to 50 wt% of a first ethylene copolymer having a weight average molecular weight Mw of 170,000 to 470,000 g / mol; and (ii) 95 to 50 wt% of a second ethylene copolymer; wherein the first ethylene copolymer has a higher weight average molecular weight Mw than the second ethylene copolymer; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) (SCB1 / SCB2) is 0.8 to 3.5; wherein the polyethylene composition has a density of 0.941 to 0.962 g / cm 3 ; a melt index, I2, of 0.5 to 5.0 g / 10 min; a melt flow ratio, I 21 / I2, of > 40; a Z-average molecular weight distribution, Mz / Mw, of > 2.5; a comonomer distribution breadth index, CDBI 50 > 50 wt%; a long chain branching factor, LCBF, of > 0.0010; wherein the polyethylene composition has greater than 70 wt% of material eluting at temperatures greater than 90°C in a temperature rising elution fractionation (CTREF) analysis.

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