Biaxially oriented film

Abstract

The biaxially oriented polyethylene film structure comprises at least three layers, at least one layer comprises a polyethylene composition, the polyethylene composition having a viscosity of 0.941 to 0.962 g / cm 3 The biaxially oriented film has a density of 0.5 to 5.0 g / 10 min, a melt index I2 of 0.5 to 5.0 g / 10 min, and a molecular weight distribution Mw / Mn of 3.0 to 8.0. The biaxially oriented film has good optical properties.

Description

[Technical Field]

[0001] This disclosure is 0.940 g / cm³. 3 This invention relates to a BOPE film or film structure made from a polyethylene composition having a density exceeding [a certain value]. [Background technology]

[0002] Biaxially oriented polyethylene (BOPE) films are prepared by stretching a thick precursor (or base) film, typically known as a cast sheet, in two directions: the machine direction (MD) and the transverse direction (TD). Stretching may be performed in a single procedure (simultaneous biaxial stretching) or in two consecutive procedures (sequential biaxial stretching). The equipment commonly used in the stretching process is generally called a "tenter frame" line.

[0003] Compared to conventional inflation films, BOPE films can achieve up to twice the stiffness (tensile modulus), resulting in improved tensile strength, impact strength, puncture resistance, and flexural crack resistance, as well as improved (i.e., reduced) optical haze.

[0004] BOPE film is suitable for a wide variety of packaging applications, and the improved properties observed in biaxially oriented films or film structures enable the design of "all-polyethylene" packaging (as opposed to packaging made with different types of polymers). Such "all-polyethylene" packaging will inherently be highly recyclable.

[0005] The tenter frame process is widely used in the preparation of biaxially oriented polypropylene (BOPP) and biaxially oriented polyethylene terephthalate (BOPET) films. However, polyethylene is relatively difficult to stretch / biaxially oriented, which limits the commercial use of BOPE. Prior to this study, in particular, high-density polyethylene compositions (e.g., at least about 0.940 g / cm³) were used. 3 High-density polyethylene compositions (with a density of 0.5%) have generally been observed to exhibit poor behavior when subjected to biaxial orientation. In fact, producing BOPE films from high-density polyethylene may require specific or precise process conditions (i.e., a very narrow process window). Alternatively; high-density polyethylene may be crosslinked before use in a biaxial orientation process; or, before biaxial orientation, high-density polyethylene may be co-extruded using promoter extrusion layers ("casting promoters") such as layers containing low-density polyethylene material and blends thereof, or layers containing ethylene / propylene copolymers and terpolymers, as adjacent co-extruded layers. Therefore, there is a need for new polyethylene compositions, particularly high-density polyethylene compositions that provide improved "stretchability" in BOPE processes, such as the Tenter-frame BOPE process. [Overview of the Initiative]

[0006] One embodiment of the present disclosure provides an "all-polyethylene" biaxially oriented film structure that has good optical properties and may have improved recyclability compared to BOPE films made from mixed polymer materials.

[0007] One embodiment of the present disclosure is a biaxially oriented film structure comprising at least three layers, wherein at least one layer comprises a polyethylene composition, and the polyethylene composition is 0.940 g / cm³ 3 This is a biaxially oriented film structure having the above density, a melt index of I2 with a melt index of 0.5-5.0 g / 10 min, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0008] One embodiment of the present disclosure is a biaxially oriented film structure comprising at least three layers, each layer comprising a polyethylene composition, wherein the polyethylene composition is 0.940 g / cm³ 3 This is a biaxially oriented film structure having the above density, a melt index of I2 with a melt index of 0.5-5.0 g / 10 min, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0009] One embodiment of the present disclosure is a biaxially oriented film structure comprising at least three layers, at least one of which comprises a polyethylene composition, wherein the polyethylene composition is 0.941 to 0.962 g / cm³ 3 It is a biaxially oriented film structure with a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0010] One embodiment of the present disclosure is a biaxially oriented film structure comprising at least three layers, each layer comprising a polyethylene composition, wherein the polyethylene composition is 0.941 to 0.962 g / cm³. 3 It is a biaxially oriented film structure with a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0011] One embodiment of the present disclosure is a biaxially oriented film structure comprising at least three adjacent layers, each of which comprises a polyethylene composition, wherein the polyethylene composition has a concentration of 0.941 to 0.962 g / cm³. 3 It is a biaxially oriented film structure with a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0012] A biaxially oriented polyethylene film structure comprising at least three layers, At least one layer comprises a polyethylene composition, Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and including, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer, The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms (SCB1) in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms (SCB2) in the second ethylene copolymer is 0.8 to 3.5, The polyethylene composition has a density of 0.941 to 0.962 g / cm 3 and a melt index I2 of 0.5 to 5.0 g / 10 min, a biaxially oriented polyethylene film structure.

[0013] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure including at least three layers, Each of the three adjacent layers contains a polyethylene composition, The polyethylene composition, (i) 15 to 50 wt% of a first ethylene copolymer, and (ii) 85 to 50 wt% of a second ethylene copolymer including, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer, The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms (SCB1) in the first ethylene copolymer to the number of short-chain branches per 1000 carbon atoms (SCB2) in the second ethylene copolymer is 0.8 to 3.5, The polyethylene composition has a density of 0.941 to 0.962 g / cm 3 and a melt index I2 of 0.5 to 5.0 g / 10 min, and is a biaxially oriented polyethylene film structure.

[0014] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure including at least three layers, Each of the three adjacent layers, A) at least 75 wt% of a polyethylene composition, and B) A polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in an amount of 25% by weight or less. Includes, Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It is a biaxially oriented polyethylene film structure with a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0015] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It is a biaxially oriented polyethylene film structure with a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0016] One embodiment of the present disclosure provides a process for preparing a biaxially oriented polyethylene film structure, The process is (a) A step of co-extruding a polyethylene composition into a base film structure having at least three adjacent layers, (b) A step of stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 10:1, (c) A step of stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1. Includes, (a) and (b) may be carried out in any order or simultaneously. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 This process has a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0017] Provided in embodiments of this disclosure is a process for preparing a biaxially oriented polyethylene film structure, The process is (a) A step of co-extruding a polymer blend containing at least 75% by weight of a polyethylene composition onto a base film structure containing at least three adjacent layers, (b) A step of stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 10:1, (c) A step of stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1. Includes, (b) and (c) may be carried out in any order or simultaneously. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min and a melt index of I2. The remaining weight of the polymer blend is a polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in this process.

[0018] One embodiment is a biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. The polyethylene composition comprises polymerized ethylene and an alpha-olefin selected from the group consisting of 1-butene, 1-hexene, and 1-octene. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3It has a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of Mw / Mn of 3.0-8.0. The biaxially oriented polyethylene film structure is a biaxially oriented polyethylene film structure having a haze value of less than 20%.

[0019] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. The polyethylene composition comprises polymerized ethylene and an alpha-olefin selected from the group consisting of 1-butene, 1-hexene, and 1-octene. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of Mw / Mn of 3.0-8.0. The biaxially oriented polyethylene film structure has a haze value of less than 20%. This is a biaxially oriented polyethylene film structure.

[0020] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, At least one layer comprises a polyethylene composition, Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0021] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, Each layer contains a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0022] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0023] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0024] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least one layer containing a polyethylene composition, Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0025] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure has a haze value of less than 20%. [Brief explanation of the drawing]

[0026] [Figure 1] The following shows gel permeation chromatography (GPC-RI) results obtained for polyethylene compositions prepared in accordance with this disclosure, using refractive index detection. [Figure 2] The following shows gel permeation chromatography obtained using Fourier transform infrared (GPC-FTIR) detection for polyethylene compositions prepared according to this disclosure. The comonomer content is shown as the number of short-chain branches per 1000 carbon atoms in the skeleton (y-axis) and in relation to the copolymer molecular weight (x-axis). [Figure 3] The temperature rise elution fractionation (CTREF) profile of a polyethylene composition prepared in accordance with this disclosure is shown. [Figure 4]The differential scanning calorimetry (DSC) and profiles of polyethylene compositions prepared in accordance with this disclosure are shown. [Figure 5] The apparent shear viscosity (Pa·s) versus apparent shear rate (s⁻¹) obtained by capillary rheology for polyethylene compositions prepared in accordance with this disclosure is shown. [Modes for carrying out the invention]

[0027] As used herein, the term “monomer” refers to a small molecule that can react chemically and chemically bond with itself or other monomers to form polymers.

[0028] As used herein, the terms "α-olefin" or "alpha-olefin" are used to describe monomers having a linear hydrocarbon chain containing 3 to 20 carbon atoms with a double bond at one end of the chain; the equivalent term is "linear α-olefin." Alpha-olefins are also called comonomers.

[0029] As used herein, the terms “polyethylene,” “polyethylene composition,” or “ethylene polymer” refer to a polymer produced from ethylene monomer and optionally one or more additional monomers, regardless of the specific catalyst or process used to produce the ethylene polymer, where polymerized ethylene is the majority monomer present in the polymer in weight % (or mol %). In the field of polyethylene, the one or more additional monomers are often called “comonomers,” and typically include α-olefins. The term “homopolymer” generally refers to a polymer containing only one type of monomer. The term “copolymer” refers to a polymer containing two or more types of monomers. Common types of polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), or extremely low-density polyethylene (ULDPE), also known as plastomers and elastomers. The term polyethylene also includes polyethylene terpolymers that may contain two or more comonomers in addition to ethylene. The term polyethylene also includes combinations or blends of the above types of polyethylene.

[0030] In this disclosure, the terms "ethylene homopolymer" or "polyethylene homopolymer" are used to refer to polymers that are products of a polymerization process in which ethylene alone is intentionally added or intentionally present as a polymerizable monomer.

[0031] In this disclosure, the terms "ethylene copolymer" or "polyethylene copolymer" mean that the polymer is a product of a polymerization process in which ethylene and one or more α-olefins are intentionally added or intentionally present as polymerizable monomers.

[0032] As used herein, the term “unsubstituted” means that a hydrogen radical is bonded to the molecular group following the term “unsubstituted.” The term “substituted” means that the group following the term has one or more moieties (non-hydrogen radicals) that replace one or more hydrogen radicals at any position within the group.

[0033] The term “film” is used herein to mean a film having one or more layers, formed by extruding a polymer through one or more die openings. The term “film structure” is used herein to mean a film having multiple layers (a film structure may have at least two, at least three, at least four, at least five, etc.).

[0034] In this disclosure, the terms “biaxially oriented polyethylene film,” “BOPE film,” “biaxially oriented polyethylene film structure,” or “BOPE film structure” generally refer to a biaxially oriented film or film structure in which polyethylene is the main component polymer (i.e., polyethylene is present in a higher weight % than other non-polyethylene polymers based on the total weight of polymers present in the film or film structure).

[0035] As used herein, the term "all-polyethylene," when used to describe a film or film structure, means that the film or film structure is composed of at least 90% by weight of polyethylene (in contrast to non-polyethylene-based polymer materials or compositions), based on the total weight of polymers present in the film or film structure.

[0036] The "skin" layer is the outer layer of a multilayer film structure (i.e., the layer with an outer surface that is exposed to the environment).

[0037] A "core" layer is an inner layer of a multilayer film structure (i.e., a layer adjacent to the inner surface of a skin layer, or a layer adjacent to another inner layer, or a layer adjacent to another core layer). A multilayer film structure may have one or more core layers that are considered adjacent inner layers.

[0038] This disclosure is 0.940 g / cm³. 3 The present invention provides a biaxially oriented film or film structure made using a polyethylene composition having the above density.

[0039] In one embodiment, the polyethylene composition is 0.940 g / cm³ 3 It has the above density, a melt index of I2 at 0.5-5.0 g / 10 min, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0040] In one embodiment, the polyethylene composition is 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of Mw / Mn of 3.0-8.0.

[0041] In one embodiment of the present disclosure, the polyethylene composition comprises the following two components: (i) a first ethylene copolymer; and (ii) a second ethylene copolymer distinct from the first ethylene copolymer. Embodiments of the first ethylene copolymer, the second ethylene copolymer, and the polyethylene composition are described below.

[0042] <First ethylene copolymer> In one embodiment of the present disclosure, the first ethylene copolymer comprises both polymerized ethylene and at least one polymerized α-olefin comonomer, with polymerized ethylene making up the majority.

[0043] In embodiments of the present disclosure, the α-olefin that can copolymerize with ethylene to produce a first ethylene copolymer may be selected from the group comprising 1-propene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and mixtures thereof.

[0044] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site catalyst, non-limiting examples of which include phosphine imine catalysts, metallocene catalysts, and constrained geometric catalysts, all of which are well known in the art.

[0045] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site polymerization catalyst ("SSC").

[0046] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site polymerization catalyst in a solution-phase polymerization process.

[0047] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a single-site polymerization catalyst having hafnium (Hf) as the active metal center.

[0048] In one embodiment of the present disclosure, the first ethylene copolymer is an ethylene / 1-octene copolymer.

[0049] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a metallocene catalyst.

[0050] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a crosslinked metallocene catalyst.

[0051] In one embodiment of the present disclosure, the first ethylene copolymer is prepared using a crosslinked metallocene catalyst having formula (I): [ka]

[0052] 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 1-20Hydrocarbyl radical, C 1-20 Alkyl radicals, or C 6-10 It is an aryl oxide radical; R2 and R3 are hydrogen atoms, C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radical or C 6-10 Independently selected from aryl oxide radicals; R4 and R5 are hydrogen atoms, unsubstituted C 1-20 Hydrocarbyl radical, substituted C 1-20 Hydrocarbyl radical, C 1-20 Alkyl radical or C 6-10 It is independently selected from the aryl oxide radical; Q is independently an activatable leaving ligand.

[0053] In one embodiment, G is carbon.

[0054] In one embodiment, R4 and R5 are independently aryl groups. In one embodiment, R4 and R5 are independently a phenyl group or a substituted phenyl group. In one embodiment, R4 and R5 are phenyl groups. In one embodiment, R4 and R5 are independently substituted phenyl groups. In one embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with substituted silyl groups. In one embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with trialkylsilyl groups. In one embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with a trialkylsilyl group at the para position. In another embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with a trimethylsilyl group at the para position. In yet another embodiment, R4 and R5 are substituted phenyl groups, and the phenyl groups are substituted with a triethylsilyl group at the para position. In one embodiment, R4 and R5 are independently alkyl groups. In one embodiment, R4 and R5 are independently alkenyl groups.

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

[0056] In one embodiment, R2 and R3 are independently hydrocarbyl groups having 1 to 30 carbon atoms. In one embodiment, R2 and R3 are independently aryl groups. In one embodiment, R2 and R3 are independently alkyl groups. In one embodiment, R2 and R3 are independently alkyl groups having 1 to 20 carbon atoms. In one embodiment, R2 and R3 are independently a phenyl group or a substituted phenyl group. In one embodiment, R2 and R3 are tert-butyl groups. In one embodiment, R2 and R3 are hydrogen.

[0057] In one embodiment, M is hafnium (Hf).

[0058] In this disclosure, the term “activatable” means that ligand Q can be cleaved from a metal center M via a protonolysis reaction, or abstracted from a metal center M by a suitable acidic or electrophilic catalytic compound (also known as a “cocatalytic” compound), examples of which are described below. Activatable ligand Q can also be converted to another ligand that is cleaved or abstracted from a metal center M (for example, a halide can be converted to an alkyl group). While we do not wish to be bound by a single theory, protonolysis or abstraction reactions generate an active “cationic” metal center capable of polymerizing olefins.

[0059] In embodiments of this disclosure, the activatable ligand Q is independently selected from the group consisting of: hydrogen atoms; halogen atoms; C 1~20 Hydrocarbyl radical, C1~20 Alkoxy radicals, and C 6-10 Aryl or aryloxy radical, where each of the hydrocarbyl, alkoxy, aryl, or aryloxy radicals may be unsubstituted or further substituted with one or more halogens or other groups; C 1-8 Alkyl; C 1-8 Alkoxy; C 6-10 Q is an aryl or aryloxy; an amide or phosphide radical, but Q is not a cyclopentadienyl. Alternatively, two Q ligands may bond to each other to form, for example, a substituted or unsubstituted diene ligand (e.g., 1,3-butadiene); or a delocalized heteroatom-containing group such as an acetate or acetamidinate group. In a convenient embodiment of this disclosure, each Q is a halide atom, C 1~4 The ligand Q is independently selected from the group consisting of alkyl radicals and benzyl radicals. Particularly suitable activatable ligands Q in embodiments of this disclosure are monoanionic ligands such as halides (e.g., chlorides) or hydrocarbyls (e.g., methyl, benzyl).

[0060] In one embodiment of the present disclosure, the single-site catalyst used to produce the first ethylene copolymer is diphenylmethylene(cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dichloride having the following molecular formula: [(2,7-tBu2Flu)Ph2C(Cp)HfCl2].

[0061] In one embodiment of the present disclosure, the single-site catalyst used to produce the first ethylene copolymer is diphenylmethylene(cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafniumdimethyl having the following molecular formula: [(2,7-tBu2Flu)Ph2C(Cp))HfMe2].

[0062] In addition to the single-site catalyst molecule itself, the active single-site catalyst system may further include one or more of the following: an alkylaluminoxane cocatalyst and an ionic activator. The single-site catalyst system may also optionally include a hindered phenol.

[0063] Although the precise structure of alkylaluminoxanes is unknown, experts in the field generally agree that they are oligomeric species containing repeating units of the following general formula: (R)2AlO-(Al(R)-O) n -Al(R)2 (In the formula, the R groups may be the same or different, and may be linear, branched, or cyclic hydrocarbyl radicals containing 1 to 20 carbon atoms, with n being 0 to about 50). An unrestricted example of alkylaluminoxane is methylaluminoxane (or MAO), where each R group is a methyl radical.

[0064] In one embodiment of the present disclosure, R of the alkylaluminoxane is a methyl radical, and m is 10 to 40.

[0065] In one embodiment of this disclosure, the cocatalyst is a modified methylaluminoxane (MMAO).

[0066] It is well known in the art that alkylaluminoxanes can play a dual role as both alkylating agents and activators. Therefore, alkylaluminoxane cocatalysts are often used in combination with activatable ligands such as halogens.

[0067] Generally, ionic surfactants consist of a cation and a bulky anion, the latter being substantially non-coordinating. A non-limiting example of an ionic surfactant is a four-coordinating boron ionic surfactant, which has four ligands bonded to the boron atom. Several formulas are shown below as non-limiting examples of boron ionic surfactants: [R 5 ] + [B(R 7)4] - (In the formula, B represents a boron atom, and R 5 is an aromatic hydrocarbyl (e.g., triphenylmethyl cation), and each R 7 This is independently selected from the following: a phenyl radical substituted with 3 to 5 substituents selected from unsubstituted or fluorine atoms, or a C substituted with unsubstituted or fluorine atoms. 1~4 Alkyl or alkoxy radicals, and formula -Si(R 9 )3 silyl radicals, where each R 9 is a hydrogen atom and C 1-4 (Selected independently of alkyl radicals), and [(R 8 ) t ZH] + [B(R 7 )4] - (In the formula, B is a boron atom, H is a hydrogen atom, Z is a nitrogen or phosphorus atom, t is 2 or 3, R 8 C 1~8 alkyl radicals, unsubstituted or up to 3 C 1-4 Selected from phenyl radicals substituted with alkyl radicals, or one R 8 R may form an anilinium radical together with the nitrogen atom, 7 (This is defined above).

[0068] In both equations, R 7A non-limiting example is the pentafluorophenyl radical. In general, boron ionic surfactants can be described as salts of tetra(perfluorophenyl)boron, and non-limiting examples include anilinium, carbonium, oxonium, phosphonium, and sulfonium salts of tetra(perfluorophenyl)boron with anilinium and trityl (or triphenylmethylium). Non-limiting examples of additional ionic surfactants include triethylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(m,m-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tri(n-butyl)ammonium tetra(o-tolyl)boron, N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)boron, and N,N-diethylanilinium N,N-2,4,6-Pentamethylanilinium tetra(phenyl)boron, di-(isopropyl)ammonium tetra(pentafluorophenyl)boron, dicyclohexylammonium tetra(phenyl)boron, triphenylphosphonium tetra(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron, tri(dimethylphenyl)phosphonium tetra(phenyl)boron, tropylium tetrakisspentafluorophenyl borate, triphenylmethylium tetrakisspentafluorophenyl borate, benzene(diazonium) tetrakisspentafluorophenyl borate, tropylium tetrakis(2,3,5,6-tetrafluorophenyl) borate, triphenylmethylium tetrakis(2,3,5,6-tetrafluorophenyl) borate, benzene(diazonium) tetrakis(3,4,Examples include 5-trifluorophenyl) borate, tropylium tetrakis(3,4,5-trifluorophenyl) borate, benzene(diazonium) tetrakis(3,4,5-trifluorophenyl) borate, tropylium tetrakis(1,2,2-trifluoroethenyl) borate, triphenylmethylium tetrakis(1,2,2-trifluoroethenyl) borate, benzene(diazonium) tetrakis(1,2,2-trifluoroethenyl) borate, tropylium tetrakis(2,3,4,5-tetrafluorophenyl) borate, triphenylmethylium tetrakis(2,3,4,5-tetrafluorophenyl) borate, and benzene(diazonium) tetrakis(2,3,4,5-tetrafluorophenyl) borate. Easily available commercial ionic surfactants include N,N-dimethylanilinium tetrakispentafluorophenyl borate and triphenylmethylium tetrakispentafluorophenyl borate.

[0069] Non-limiting examples of hindered phenols include butylated phenol antioxidants, butylated hydroxytoluene, 2,6-di-tert-butyl-4-ethylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate.

[0070] To generate an active single-site catalytic system, the amounts and molar ratios of three or four components—a single-site catalyst molecule (e.g., metallocene), an alkylaluminoxane, an ionic activator, and an optional hindered phenol—are optimized.

[0071] In one embodiment of the present disclosure, a single-site catalyst used to produce a first ethylene copolymer generates long-chain branching, and the first ethylene copolymer contains long-chain branching (hereinafter referred to as "LCB").

[0072] Long chain branching (LCB) is a well-known structural phenomenon in ethylene copolymers and is well known to those skilled in the art. Conventionally, there are three methods for LCB analysis: nuclear magnetic resonance (NMR) spectroscopy (see, e.g., J. C Randall, J. Macromol. Sci., Rev., Macromol. Chem. Phys., 1989, Vol. 29, p. 201); triple-detection SEC with DRI, viscometer, and low-angle laser light scattering detector (see, e.g., W. W. Yau and D. Hill, Int. J. Polym. Anal. Character., 1996, Vol. 2, p. 151); and rheology (see, e.g., W. W. Graessley, Acc. Chem. Res., 1977, Vol. 10, pp. 332-339). In embodiments of this disclosure, the long chain branching is essentially polymeric, i.e., long enough to be observed in NMR spectra, triple-detector SEC experiments, or rheological experiments.

[0073] In one embodiment of the present disclosure, the first ethylene copolymer includes long-chain branching characterized by the long-chain branching coefficient LCBF disclosed herein. In embodiments of the present disclosure, the upper limit of the LCBF of the first ethylene copolymer may be 0.5000, 0.4000, or 0.3000 (dimensionless). In embodiments of the present disclosure, the lower limit of the LCBF of the first ethylene copolymer may be 0.0010, 0.0015, 0.0020, 0.0100, 0.0500, or 0.1000 (dimensionless).

[0074] The first ethylene copolymer may contain catalyst residues that reflect the chemical composition of the catalyst formulation used to produce it. Those skilled in the art will understand that catalyst residues are typically quantified by parts per million of metal in the first ethylene copolymer (or polyethylene composition; see below), where the metals present are derived from the metals in the catalyst formulation used to produce it. Non-limiting examples of metal residues that may be present include Group IV metals, titanium, zirconium, and hafnium. In embodiments of the present disclosure, the upper limit of the ppm of metal in the first ethylene copolymer may be about 3.0 ppm, in other cases about 2.0 ppm, and in yet other cases about 1.5 ppm. In embodiments of the present disclosure, the lower limit of the ppm of metal in the first ethylene copolymer may be about 0.03 ppm, in other cases about 0.09 ppm, and in yet other cases about 0.15 ppm.

[0075] The short-chain branching in the first ethylene copolymer (i.e., short-chain branching per 1000 carbon atoms in the skeleton, SCB1 or SCB1 / 1000C) is due to the presence of α-olefin comonomers in the first ethylene copolymer, and for example, in the case of 1-butene comonomer there are 2 carbon atoms, in the case of 1-hexene comonomer there are 4 carbon atoms, or in the case of 1-octene comonomer there are 6 carbon atoms.

[0076] In one embodiment of the present disclosure, the first ethylene copolymer has 1 to 50 short-chain branches (SCB1) per 1,000 carbon atoms. In a further embodiment, the first ethylene copolymer has 1 to 25 short-chain branches (SCB1) per 1,000 carbon atoms, or 1 to 15 short-chain branches (SCB1) per 1,000 carbon atoms, or 1 to 10 short-chain branches (SCB1) per 1,000 carbon atoms.

[0077] In one embodiment of the present disclosure, the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1) is greater than the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer (SCB2).

[0078] In one embodiment of the present disclosure, the first ethylene copolymer has 0.5 to 25.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 0.5 to 20.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 0.5 to 15.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 0.5 to 10.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 0.5 to 7.5 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 0.5 to 5.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 25 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 20.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 15.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 10.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 7.5 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.0 to 5.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 1.5 to 25 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 1.5 to 20.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 1.5 to 15.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 1.5 to 10.0 short-chain branches (SCB1) per 1000 carbon atoms.In one embodiment of this disclosure, the first ethylene copolymer has 1.5 to 7.5 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 1.5 to 5.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 25 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 20.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 15.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of this disclosure, the first ethylene copolymer has 2.0 to 10.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.0 to 7.5 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.0 to 5.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.3 to 25.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.3 to 20.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.3 to 15.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.3 to 10.0 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.3 to 7.5 short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has 2.3 to 5.0 short-chain branches (SCB1) per 1000 carbon atoms.

[0079] In one embodiment of the present disclosure, the first ethylene copolymer has fewer than 10 (<10) short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has fewer than 7.5 (<7.5) short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has fewer than 5.0 (<5.0) short-chain branches (SCB1) per 1000 carbon atoms. In one embodiment of the present disclosure, the first ethylene copolymer has fewer than 4.0 (<4.0) short-chain branches (SCB1) per 1000 carbon atoms.

[0080] In one embodiment of the present disclosure, the density of the first copolymer is less than the density of the second ethylene copolymer.

[0081] In one embodiment of this disclosure, the first ethylene copolymer is 0.910 to 0.975 g / cm³ 3 It has a density of 0.930 to 0.970 g / cm³, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the first ethylene copolymer has a density of 0.930 to 0.970 g / cm³. 3 , or 0.930~0.965 g / cm³ 3 , or 0.930~0.960 g / cm³ 3 , or 0.935~0.965 g / cm³ 3 , or 0.935~0.960 g / cm³ 3 , or 0.935~0.955 g / cm³ 3 , or 0.935~0.950 g / cm³ 3 , or 0.930~0.950 g / cm³ 3 , or 0.930~0.955 g / cm³ 3 It has a density of . In other embodiments of the present disclosure, the first ethylene copolymer has a density of 0.915 to 0.945 g / cm³. 3 , or 0.915~0.940 g / cm³ 3 , or 0.915~0.935 g / cm³ 3 , or 0.915~0.930 g / cm³ 3 , or 0.920~0.930 g / cm³ 3 It has a density of .

[0082] In embodiments of the present disclosure, the first ethylene copolymer has a melt index I2 of 5.0 g / 10 min or less, or less than 5.0 g / 10 min, or 2.5 g / 10 min or less, or less than 2.5 g / 10 min, or 1.0 g / 10 min or less, or less than 1.0 g / 10 min, or 0.5 g / 10 min or less, or less than 0.5 g / 10 min, or 0.4 g / 10 min or less, or less than 0.4 g / 10 min, or 0.2 g / 10 min or less, or less than 0.2 g / 10 min.

[0083] In embodiments of the present disclosure, the first ethylene copolymer has a melt index I2 of 0.001 to 5.0 g / 10 min, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the melt index I2 of the first ethylene copolymer may be 0.01 to 5.0 g / 10 min, or 0.01 to 2.5 g / 10 min, or 0.01 to 2.0 g / 10 min, or 0.01 to 1.5 g / 10 min, or 0.01 to 1.0 g / 10 min, or 0.01 to 0.5 g / 10 min, or 0.01 to 0.4 g / 10 min, or 0.01 to 0.2 g / 10 min.

[0084] In one embodiment of the present disclosure, the melt index I2 of the first ethylene copolymer is smaller than the melt index I2 of the second ethylene copolymer.

[0085] In embodiments of this disclosure, the first ethylene copolymer has a weight-average molecular weight M greater than 170,000 g / mol, greater than 175,000 g / mol, or greater than 200,000 g / mol. w It holds.

[0086] In embodiments of this disclosure, the first ethylene copolymer has a weight-average molecular weight M of 150,000 to 500,000 g / mol. whas, and includes any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the first ethylene copolymer has a weight average molecular weight M of 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 w In other embodiments of the present disclosure, the first ethylene copolymer has a weight average molecular weight M of 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 w has.

[0087] In one embodiment of the present disclosure, the weight average molecular weight Mw of the first ethylene copolymer is higher than the weight average molecular weight Mw of the second ethylene copolymer.

[0088] In one embodiment of the present disclosure, the first ethylene copolymer has a melt flow ratio I 21 / I2 less than 25, or less than 23, or less than 20.

[0089] In embodiments of the present disclosure, the molecular weight distribution M w / M n of the first ethylene copolymer may have an upper limit of about 2.7, or about 2.5, or about 2.4, or about 2.3, or about 2.2. In embodiments of the present disclosure, the molecular weight distribution M w / M n of the first ethylene copolymer may have a lower limit of about 1.6, or about 1.7, or about 1.8, or about 1.9.

[0090] In an embodiment of the present disclosure, the first ethylene copolymer has a molecular weight distribution M w / M n of 3.0 or less, or less than 3.0, or 2.7 or less, or less than 2.7, or 2.5 or less, or less than 2.5, or 2.3 or less, or less than 2.3, or 2.1 or less, or less than 2.1, or about 2. w / M n In another embodiment of the present disclosure, the first ethylene copolymer has a molecular weight distribution M w / M n of 1.7 to 3.0, including any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the first ethylene copolymer has a molecular weight distribution M

[0091] / M 50 of 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.

[0092] In one embodiment of the present disclosure, a single-site catalyst that gives an ethylene copolymer having at least 65 wt%, or at least 70 wt%, or at least 75 wt%, or at least 80 wt%, or at least 85 wt% of CDBI during solution phase polymerization in a single reactor is used in the preparation of the first ethylene copolymer.In embodiments of the present disclosure, the weight percentage (wt%) of the first ethylene copolymer in the polyethylene composition (i.e., the weight percentage of the first ethylene copolymer based on the total weight of the first and second ethylene copolymers) may be about 5 wt% to about 60 wt%, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the weight percentage (W%) of the first ethylene copolymer in the polyethylene copolymer composition may be about 5% to about 50% by weight, or about 10% to about 50% by weight, or about 15% to about 50% by weight, or about 10% to about 45% by weight, or about 15% to about 45% by weight, or about 10% to about 40% by weight, or about 15% to about 40% by weight, or about 10% to about 35% by weight, or about 15% to about 35% by weight, or about 20% to about 50% by weight, or about 20% to about 45% by weight, or about 20% to about 40% by weight.

[0093] <Second Ethylene Copolymer> In one embodiment of the present disclosure, the second ethylene copolymer comprises both polymerized ethylene and at least one polymerized α-olefin comonomer, with polymerized ethylene making up the majority.

[0094] In embodiments of this disclosure, the α-olefin that can copolymerize with ethylene to produce a second ethylene copolymer may be selected from the group comprising 1-propene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and mixtures thereof.

[0095] In one embodiment of the present disclosure, the second ethylene copolymer is prepared using a multi-site catalyst system, non-limiting examples of which include Ziegler-Natta catalysts and chromium catalysts, both of which are well known in the art.

[0096] In one embodiment of the present disclosure, the second ethylene copolymer is prepared using a Ziegler-Natta catalyst system.

[0097] In one embodiment of the present disclosure, the second ethylene copolymer is prepared using a Ziegler-Natta catalyst system in a solution-phase polymerization process.

[0098] The Ziegler-Natta catalyst system is well known to those skilled in the art. The Ziegler-Natta catalyst may be an in-line or batch-type Ziegler-Natta catalyst system. The term "in-line Ziegler-Natta catalyst system" refers to the continuous synthesis of a small amount of active Ziegler-Natta catalyst system and its immediate injection into at least one continuous-operating reactor, where the catalyst polymerizes ethylene with one or more optionally selected α-olefins to form an ethylene polymer. The terms "batch-type Ziegler-Natta catalyst system" or "batch-type Ziegler-Natta pro-catalyst" refer to the synthesis of a much larger amount of catalyst or pro-catalyst in one or more mixing vessels, located outside or separated from a continuously operating solution polymerization process. The prepared batch-type Ziegler-Natta catalyst system, or batch-type Ziegler-Natta pro-catalyst, is transferred to a catalyst storage tank. The term "pro-catalyst" refers to an inert catalyst system (inert with respect to ethylene polymerization), and the pro-catalyst is converted to an active catalyst by the addition of an alkylaluminum co-catalyst. If necessary, the pro-catalyst is pumped from the storage tank to at least one continuous-operation reactor, where the active catalyst polymerizes ethylene and one or more optional α-olefins to form an ethylene copolymer. The pro-catalyst may be converted to an active catalyst in the reactor, outside the reactor, or en route to the reactor.

[0099] A wide variety of compounds can be used to synthesize an activated Ziegler-Natta catalyst system. The following describes various compounds that can be combined to produce an activated Ziegler-Natta catalyst system. Those skilled in the art will understand that the embodiments described herein are not limited to the specific compounds disclosed.

[0100] The activated Ziegler-Natta catalyst system can be formed from magnesium compounds, chloride compounds, metal compounds, alkylaluminum co-catalysts, and aluminum alkyls. As will be understood by those skilled in the art, the Ziegler-Natta catalyst system may also contain additional components, non-limiting examples of which are electron donors, such as amines or ethers.

[0101] Non-limiting examples of active in-line (or batch) Ziegler-Natta catalyst systems can be prepared as follows: In the first step, a solution of a magnesium compound is reacted with a solution of a chloride compound to form a magnesium chloride support suspended in solution. Non-limiting examples of magnesium compounds include Mg(R) 1 )2 is given, and in the formula, R 1 The groups may be the same or different, and may be linear, branched, or cyclic hydrocarbyl radicals containing 1 to 10 carbon atoms. Non-limiting examples of chloride compounds include R 2 Cl is mentioned, and in the formula, R 2 represents a linear, branched, or cyclic hydrocarbyl radical containing a hydrogen atom or 1 to 10 carbon atoms. In the first step, the solution of the magnesium compound may contain an aluminum alkyl compound. Non-limiting examples of aluminum alkyl compounds include Al(R 3 )3 is given, and in the formula, R 3 The groups may be the same or different, and may be linear, branched, or cyclic hydrocarbyl radicals containing 1 to 10 carbon atoms. In the second step, a solution of the metal compound is added to a solution of magnesium chloride to support the metal compound on the magnesium chloride. Non-limiting examples of suitable metal compounds include M(X) n or MO(X) nExamples include the following formulas, where M represents a metal selected from groups 4-8 of the periodic table, or a mixture of metals selected from groups 4-8; O represents oxygen; X represents a chloride or bromide; and n is an integer from 3 to 6 that satisfies the oxidation state of the metal. Additional non-limiting examples of suitable metal compounds include group 4-8 metal alkyls, metal alkoxides (which can be prepared by reacting a metal alkyl with an alcohol), and mixed ligand metal compounds, including mixtures of halides, alkyls, and alkoxide ligands. In one embodiment of this disclosure, a suitable metal compound is titanium tetrachloride (TiCl4). In the third step, a solution of the alkylaluminum cocatalyst is added to the metal compound supported on magnesium chloride. A wide variety of alkylaluminum cocatalysts are suitable, as represented by the following formula: Al(R 4 ) p (OR 9 ) q (X) r (In the formula, R 4 The groups may be the same or different, and may be hydrocarbyl groups having 1 to 10 carbon atoms, OR 9 The groups may be the same or different, and may be an alkoxy group or an aryloxy group, R 9 X is a hydrocarbyl group having 1 to 10 carbon atoms bonded to oxygen, where X is a chloride or bromide, and (p+q+r)=3, where p is greater than 0. Non-limiting examples of commonly used alkylaluminum cocatalysts include trimethylaluminum, triethylaluminum, tributylaluminum, dimethylaluminum methoxide, diethylaluminum ethoxide, dibutylaluminum butoxide, dimethylaluminum chloride or bromide, diethylaluminum chloride or bromide, dibutylaluminum chloride or bromide, and ethylaluminum dichloride or dibromide.

[0102] The process described in the above paragraph for synthesizing an active in-line (or batch) Ziegler-Natta catalyst system can be carried out in a variety of solvents, and non-limiting examples of solvents include linear or branched C5-C 12 Examples include alkanes or mixtures thereof.

[0103] The second ethylene copolymer may contain catalyst residues that reflect the chemical composition of the catalyst formulation used to produce it. Those skilled in the art will understand that catalyst residues are typically quantified by parts per million of metal in the second ethylene copolymer (or polyethylene composition; see below), where the metals present are derived from the metals in the catalyst formulation used to produce it. Non-limiting examples of metal residues that may be present include Group IV metals, titanium, zirconium, and hafnium. In embodiments of the present disclosure, the upper limit of the ppm of metal in the second ethylene copolymer may be about 3.0 ppm, in other cases about 2.0 ppm, and in yet other cases about 1.5 ppm. In embodiments of the present disclosure, the lower limit of the ppm of metal in the second ethylene copolymer may be about 0.03 ppm, in other cases about 0.09 ppm, and in yet other cases about 0.15 ppm.

[0104] The short-chain branching in the second ethylene copolymer (i.e., short-chain branching per 1000 carbon atoms in the backbone, SCB2 or SCB2 / 1000C) is due to the presence of α-olefin comonomers in the first ethylene copolymer, and for example, it has 2 carbon atoms in the case of 1-butene comonomer, 4 carbon atoms in the case of 1-hexene comonomer, and 6 carbon atoms in the case of 1-octene comonomer.

[0105] In one embodiment of the present disclosure, the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer (SCB2) is less than the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1).

[0106] In one embodiment of the present disclosure, the second ethylene copolymer has 0.5 to 15.0 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 0.5 to 10.0 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 0.5 to 5.0 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 0.5 to 2.5 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 0.5 to 2.2 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 1.0 to 15.0 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 1.0 to 10.0 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 1.0 to 5.0 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 1.0 to 2.5 short-chain branches (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has 1.0 to 2.2 short-chain branches (SCB2) per 1000 carbon atoms.

[0107] In one embodiment of the present disclosure, the second ethylene copolymer has less than 5.0 (<5.0) short-chain branchings (SCB2) per 1000 carbon atoms. In one embodiment of the present disclosure, the second ethylene copolymer has less than 3.0 (<3.0) short-chain branchings (SCB2) per 1000 carbon atoms.

[0108] In one embodiment of the present disclosure, the density of the second copolymer is greater than the density of the first ethylene copolymer.

[0109] In one embodiment of this disclosure, the second ethylene copolymer is 0.920 to 0.975 g / cm³ 3It has a density of 0.940 to 0.970 g / cm³, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the second ethylene copolymer has a density of 0.940 to 0.970 g / cm³. 3 , or 0.940~0.965 g / cm³ 3 , or 0.940~0.960 g / cm³ 3 , or 0.942~0.967 g / cm³ 3 , or 0.942~0.965 g / cm³ 3 , or 0.942~0.960 g / cm³ 3 , or 0.940~0.955 g / cm³ 3 , or 0.935~0.960 g / cm³ 3 , or 0.935~0.955 g / cm³ 3 , or 0.942~0.955 g / cm³ 3 , or 0.945~0.955 g / cm³ 3 It has a density of . In other embodiments of the present disclosure, the second ethylene copolymer has a density of 0.920 to 0.960 g / cm³. 3 , or 0.920~0.955 g / cm³ 3 , or 0.920~0.950 g / cm³ 3 , or 0.920~0.945 g / cm³ 3 , or 0.920~0.940 g / cm³ 3 It has a density of .

[0110] In embodiments of the present disclosure, the second ethylene copolymer has a melt index I2 of 10.0 g / 10 min or more, or greater than 10.0 g / 10 min, or greater than 20.0 g / 10 min, or greater than 20 g / 10 min, or greater than 25.0 g / 10 min, or greater than 25 g / 10 min.

[0111] In embodiments of the present disclosure, the second ethylene copolymer has a melt index I2 of 10 to 1,000, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the melt index I2 of the second ethylene copolymer is 10 to 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.

[0112] In one embodiment of the present disclosure, the melt index I2 of the second ethylene copolymer is greater than the melt index I2 of the first ethylene copolymer.

[0113] In one embodiment of the present disclosure, the second ethylene copolymer has a weight-average molecular weight M of 75,000 g / mol or less, or 60,000 g / mol or less, or 50,000 g / mol or less, or 45,000 g / mol or less. w In another embodiment, the second ethylene copolymer has a weight-average molecular weight M of 5,000 to 75,000 g / mol. w It has a range that includes any narrow range within this range and any value contained within these ranges. For example, in embodiments of the present disclosure, the second ethylene copolymer has a weight-average molecular weight M of 10,000 to 75,000 g / mol, or 15,000 to 75,000 g / mol, or 15,000 to 65,000 g / mol, or 15,000 to 60,000 g / mol, or 15,000 to 50,000 g / mol, or 20,000 to 60,000 g / mol, or 20,000 to 55,000 g / mol, or 20,000 to 50,000 g / mol, or 20,000 to 45,000 g / mol, or 30,000 to 55,000 g / mol, or 30,000 to 50,000 g / mol. w It holds.

[0114] In one embodiment of the present disclosure, the weight-average molecular weight Mw of the second ethylene copolymer is lower than the weight-average molecular weight Mw of the first ethylene copolymer.

[0115] In embodiments of the present disclosure, the second ethylene copolymer has a molecular weight distribution M of 2.3 or more, or greater than 2.3, or greater than 2.5, or greater than 2.5, or greater than 2.7, or greater than 2.7, or greater than 2.9, or greater than 2.9, or greater than 3.0, or greater than 3.0. w / M n In embodiments of the present disclosure, the second ethylene copolymer has a molecular weight distribution M of 2.3-6.0, or 2.3-5.5, or 2.3-5.0, or 2.3-4.5, or 2.3-4.0, or 2.3-3.5, or 2.3-3.0, or 2.5-5.0, or 2.5-4.5, or 2.5-4.0, or 2.5-3.5, or 2.7-5.0, or 2.7-4.5, or 2.7-4.0, or 2.7-3.5. w / M n It holds.

[0116] In one embodiment of the present disclosure, less than 60% by weight or less than 50% by weight of CDBI is added during solution-phase polymerization in a single reactor. 50 A multi-site catalyst that yields an ethylene copolymer having [a specific characteristic] is used to prepare a second ethylene copolymer.

[0117] In embodiments of the present disclosure, the weight percentage (wt%) of the second ethylene copolymer in the polyethylene composition (i.e., the weight percentage of the second ethylene copolymer based on the total weight of the first and second ethylene copolymers) may be about 95 wt% to about 40 wt%, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the weight percentage (W%) of the second ethylene copolymer in the polyethylene copolymer composition may be about 95% to about 50% by weight, or about 90% to about 50% by weight, or about 85% to about 50% by weight, or about 90% to about 55% by weight, or about 85% to about 55% by weight, or about 90% to about 60% by weight, or about 85% to about 60% by weight, or about 90% to about 65% by weight, or about 85% to about 65% by weight, or about 80% to about 50% by weight, or about 80% to about 55% by weight, or about 80% to about 60% by weight.

[0118] <Polyethylene composition> In one embodiment of this disclosure, the polyethylene composition is 0.940 g / cm³ 3 It has the above densities, a melt index of I2 at 0.2-10.0 g / 10 min, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0119] In one embodiment of this disclosure, the polyethylene composition is 0.940 g / cm³ 3 It has the above density, a melt index of I2 at 0.5-5.0 g / 10 min, and a molecular weight distribution Mw / Mn of 3.0-8.0.

[0120] In one embodiment of this disclosure, the polyethylene composition is 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of Mw / Mn of 3.0-8.0.

[0121] In one embodiment of the present disclosure, the polyethylene composition comprises ethylene and one or more alphaolefins selected from the group consisting of 1-butene, 1-hexene, 1-octene and mixtures thereof.

[0122] In one embodiment of the present disclosure, the polyethylene composition comprises ethylene and one or more alpha-olefins selected from the group consisting of 1-butene, 1-hexene, and 1-octene.

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

[0124] In one embodiment of the present disclosure, the polyethylene composition comprises ethylene and 1-octene.

[0125] In one embodiment of the present disclosure, the polyethylene composition comprises a first ethylene copolymer and a second ethylene copolymer (each as defined in the embodiments above).

[0126] The polyethylene compositions disclosed herein can be made using any well-known techniques in the art in certain embodiments, including, but not limited to, melt blending, solution blending, or in-reactor blending to combine the first ethylene copolymer and the second ethylene copolymer.

[0127] In one embodiment, the polyethylene composition of the present disclosure is made by producing a first ethylene copolymer using a single-site catalyst in a first reactor and a second ethylene copolymer using a multi-site catalyst in a second reactor.

[0128] In one embodiment, the polyethylene composition of the present disclosure is made by forming a first ethylene copolymer by polymerizing ethylene and an alpha-olefin using a single-site catalyst in a first reactor; and forming a second ethylene copolymer by polymerizing ethylene and an alpha-olefin using a multi-site catalyst in a second reactor.

[0129] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin using a single-site catalyst in a first solution-phase polymerization reactor to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin using a multi-site catalyst in a second solution-phase polymerization reactor to form a second ethylene copolymer.

[0130] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin using a single-site catalyst in a first solution-phase polymerization reactor to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin using a multi-site catalyst in a second solution-phase polymerization reactor to form a second ethylene copolymer, wherein the first and second solution-phase polymerization reactors are configured in series with respect to each other.

[0131] In one embodiment, the polyethylene composition of the present disclosure is prepared by polymerizing ethylene and α-olefin using a single-site catalyst in a first solution-phase polymerization reactor to form a first ethylene copolymer; and by polymerizing ethylene and α-olefin using a multi-site catalyst in a second solution-phase polymerization reactor to form a second ethylene copolymer, wherein the first and second solution-phase polymerization reactors are configured in parallel with each other.

[0132] In this embodiment, the solution-phase polymerization reactor used as the first solution-phase reactor is a continuous-stirred tank reactor or a tubular reactor.

[0133] 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.

[0134] In solution-phase polymerization, monomers are dissolved / dispersed in the solvent before being supplied to the reactor (or, in the case of gaseous monomers, the monomers may be supplied to the reactor and dissolved in the reaction mixture). Before mixing, the solvent and monomers are generally purified to remove potential catalyst poisons such as water, oxygen, and metal impurities. Purification of the feedstocks follows standard practices in the art. For example, molecular sieves, alumina beds, and oxygen removal catalysts are used for monomer purification. The solvent itself (e.g., methylpentane, cyclohexane, hexane, or toluene) is preferably treated in a similar manner.

[0135] The raw materials may be heated or cooled before being supplied to the reactor.

[0136] Generally, catalyst components may be pre-mixed in the reaction solvent or supplied to the reactor as a separate stream. In some cases, it may be desirable to pre-mix the catalyst components before they enter the polymerization reaction zone to ensure sufficient reaction time. Such "in-line mixing" techniques are well known to those skilled in the art.

[0137] Solution polymerization processes for the polymerization or copolymerization of ethylene are well known in the art (see, for example, U.S. Patents 6,372,864 and 6,777,509). These processes are carried out in the presence of an inert hydrocarbon solvent. In solution-phase polymerization reactors, a variety of solvents can be used as process solvents, and non-limiting examples include linear, branched, or cyclic C5-C5 polymers. 12 Alkanes are examples. Suitable catalytic solvents include aliphatic hydrocarbons and aromatic hydrocarbons. Non-limiting examples of aliphatic catalytic solvents include linear, branched, or cyclic C5-C5 12Aliphatic hydrocarbons include, for example, pentane, methylpentane, hexane, heptane, octane, cyclohexane, cyclopentane, methylcyclohexane, naphtha hydrogenates, or combinations thereof. Non-limiting examples of aromatic catalyst solvents include benzene, toluene (methylbenzene), ethylbenzene, o-xylene (1,2-dimethylbenzene), m-xylene (1,3-dimethylbenzene), p-xylene (1,4-dimethylbenzene), mixtures of xylene isomers, hemeritene (1,2,3-trimethylbenzene), pseudocumene (1,2,4-trimethylbenzene), mesitylene (1,3,5-trimethylbenzene), mixtures of trimethylbenzene isomers, prehenytene (1,2,3,4-tetramethylbenzene), durene (1,2,3,5-tetramethylbenzene), mixtures of tetramethylbenzene isomers, pentamethylbenzene, hexamethylbenzene, and combinations thereof.

[0138] In embodiments of this disclosure, the polymerization temperature in a conventional solution process may be about 80°C to about 300°C. In one embodiment of this disclosure, the polymerization temperature in a solution process is about 120°C to about 250°C.

[0139] In embodiments of the present disclosure, the polymerization pressure in the solution process may be a “medium-pressure process,” meaning that the pressure in the reactor is less than about 6,000 psi (about 42,000 kilopascals or kPa). In embodiments of the present disclosure, the polymerization pressure in the solution process may be about 10,000 to about 40,000 kPa, or about 14,000 to about 22,000 kPa (i.e., about 2,000 psi to about 3,000 psi).

[0140] In embodiments of this disclosure, the comonomer (i.e., α-olefin) suitable for copolymerization with ethylene in a solution-phase polymerization process is C 3-20 This includes monoolefins and diolefins. In embodiments of this disclosure, comonomers copolymerizable with ethylene are unsubstituted or contain up to two C molecules. 1-6 C substituted with alkyl radicals 3-12α-olefin, unsubstituted or C 1-4 C is substituted with up to two substituents selected from the group consisting of alkyl radicals. 8-12 Vinyl aromatic monomers, unsubstituted or C 1-4 C substituted with alkyl radicals 4-12 This includes linear or cyclic diolefins. In further embodiments of the present disclosure, α-olefins copolymerizable with ethylene are one or more propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene, styrene, alpha-methylstyrene, and restricted cyclic olefins, such as cyclobutene, cyclopentene, dicyclopentadiene, norbornene, alkyl-substituted norbornene, alkenyl-substituted norbornene (e.g., 5-methylene-2-norbornene and 5-ethylidene-2-norbornene, bicyclo-(2,2,1)-hepta-2,5-diene).

[0141] In embodiments of the present disclosure, the polyethylene composition has one or more α-olefins in 0.01 to 5 mole percent, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has one or more α-olefins in 0.05 to 5.0 mole percent, or one or more α-olefins in 0.05 to 2.5 mole percent, or one or more α-olefins in 0.05 to 1.5 mole percent, or one or more α-olefins in 0.05 to 1.0 mole percent, or one or more α-olefins in 0.1 to 2.5 mole percent, or one or more α-olefins in 0.1 to 1.5 mole percent, or one or more α-olefins in 0.1 to 1.0 mole percent.

[0142] In embodiments of the present disclosure, the polyethylene composition contains 0.05 to 5.0 mole percent of 1-octene, or 0.05 to 2.5 mole percent of 1-octene, or 0.05 to 1.5 mole percent of 1-octene, or 0.05 to 1.0 mole percent of 1-octene, or 0.1 to 2.5 mole percent of 1-octene, or 0.1 to 1.5 mole percent of 1-octene, or 0.10 to 1.0 mole percent of 1-octene.

[0143] In embodiments of the present disclosure, a polyethylene composition comprising a first ethylene copolymer and a second ethylene copolymer (as defined above) has a ratio (SCB1 / SCB2) of less than 5.0, or less than 4.0, or less than 3.0, or less than 2.5, or less than 2.0, of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (i.e., SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (i.e., SCB2).

[0144] In embodiments of this disclosure, a polyethylene composition comprising a first ethylene copolymer and a second ethylene copolymer (as defined above) has a ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (i.e., SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (i.e., SCB2) of 0.8 to 5.0, or 0.8 to 3.5, or 0.8 to 3. 0.0, or 1.0-5.0, or 1.0-4.0, or 1.0-3.5, or 1.0-3.0, or 1.0-2.8, or 1.0-2.5, or 1.0-2.0, or 1.0-1.5, or 0.8-2.8, or 0.8-2.5, or 0.8-2.0, or 0.8-1.5, or greater than 1.0-5.0, or greater than 1.0-4.0, or greater than 1.0-3.5, or greater than 1.0-3.0, or greater than 1.0-2.8, or greater than 1.0-2.5.

[0145] In embodiments of this disclosure, the polyethylene composition has a weight-average molecular weight M of 65,000 to 250,000 g / mol. WIt has and includes any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the polyethylene composition has a weight average molecular weight M of 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 W It has.

[0146] In one embodiment of the present disclosure, the polyethylene composition has a number average molecular weight M of 60,000 g / mol or less, or 50,000 g / mol or less, or less than 50,000 g / mol, or 45,000 g / mol or less, or less than 45,000 g / mol, or 40,000 g / mol or less, or less than 40,000 g / mol, or 35,000 g / mol or less, or less than 35,000 g / mol, or 30,000 g / mol or less, or less than 30,000 g / mol, or 25,000 g / mol or less, or less than 25,000 g / mol n It has. In a further embodiment of the present disclosure, the polyethylene composition has a number average molecular weight M of 5,000 to 60,000 g / mol n It has and includes any narrow range within this range and any value included in these ranges. For example, in an embodiment of the present disclosure, the polyethylene composition has a number average molecular weight M of 10,000 to 55,000 g / mol, or 10,000 to 50,000 g / mol, or 15,000 to 50,000 g / mol, or 15,000 to 45,000 g / mol, or 15,000 to 40,000 g / mol, or 15,000 to 35,000 g / mol, or 15,000 to 30,000 g / mol, or 20,000 to 30,000 g / mol n It has.

[0147] In one embodiment of the present disclosure, the polyethylene composition has a Z average molecular weight M of 250,000 g / mol or more, or 275,000 g / mol or more z It has.

[0148] In further embodiments of this disclosure, the polyethylene composition has a Z-average molecular weight M of 250,000 to 600,000 g / mol. z It has and includes any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a Z-average molecular weight M of 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 to 450,000 g / mol. z It holds.

[0149] In one embodiment of the present disclosure, the polyethylene copolymer composition has a bimodal profile (i.e., a bimodal molecular weight distribution) in gel permeation chromatography (GPC) analysis.

[0150] In one embodiment of the present disclosure, the polyethylene copolymer composition has a bimodal profile in a gel permeation chromatograph produced according to the method of ASTM D6474-99.

[0151] The term "unimodal" is defined herein as meaning that in a GPC curve, there is only one clear and significant peak or maximum. In contrast, the use of the term "bimodal" means that, in addition to the first peak, there is a second peak or shoulder representing a higher or lower molecular weight component (i.e., the molecular weight distribution can be said to have two maximums in the molecular weight distribution curve). Alternatively, the term "bimodal" means that in a molecular weight distribution curve generated according to the method of ASTM D6474-99, there are two maximums. The term "multimodal" means that in a molecular weight distribution curve generated according to the method of ASTM D6474-99, there are two or more, typically more than two, maximums.

[0152] In embodiments of this disclosure, the polyethylene composition has a molecular weight distribution M of 8.0 or less, or less than 8.0, or 7.0 or less, or less than 7.0, or 6.5 or less, or less than 6.5, or 6.0 or less, or less than 6.0, or 5.5 or less, or less than 5.5, or less than 5.0, or less than 5.0. w / M n In embodiments of this disclosure, the polyethylene composition has a molecular weight distribution M of 3.0 or more, or greater than 3.0, or greater than 3.5. w / M n It holds.

[0153] In embodiments of this disclosure, the polyethylene composition has a molecular weight distribution of 2.9 to 8.0 M w / M n Having, and including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a molecular weight distribution M of 3.0 to 8.0, or 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, or 3.0 to 6.5, or 3.0 to 6.0, or 3.0 to 5.5, or 3.0 to 5.0. w / M n It holds.

[0154] In embodiments of the present disclosure, the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 2.5 or more, or 2.6 or more, or 2.7 or more, or 2.8 or more, or greater than 2.5, or greater than 2.6, or greater than 2.7, or greater than 2.8.

[0155] In embodiments of the present disclosure, the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 2.5 to 4.5, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 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.

[0156] In embodiments of this disclosure, the polyethylene copolymer composition is 0.940 g / cm³ 3 Above, or 0.941 g / cm³ 3 Above, or 0.942 g / cm³ 3 Above, or 0.943 g / cm³ 3 It has the above density.

[0157] In embodiments of this disclosure, the polyethylene composition is 0.940 to 0.970 g / cm³. 3 It has a density of 0.940 to 0.965 g / cm³, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition is 0.940 to 0.965 g / cm³. 3 , or 0.941~0.965 g / cm³ 3 , or 0.940~0.962 g / cm³ 3 , or 0.941~0.962 g / cm³ 3 , or 0.941~0.960 g / cm³ 3 , or 0.941~0.957 g / cm³ 3 , or 0.941~0.954 g / cm³ 3 , or 0.941~0.952 g / cm³ 3 , or 0.940~0.960 g / cm³ 3 , or 0.940~0.957 g / cm³ 3 , or 0.940~0.954 g / cm³ 3 , or 0.940~0.952 g / cm³ 3 , or 0.942~0.954 g / cm³ 3 , or 0.942~0.952 g / cm³ 3 It has a density of .

[0158] In embodiments of this disclosure, the polyethylene composition has a melt index I2 of 0.001 to 10.0 g / 10 min, including any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of this disclosure, the melt index I2 of the polyethylene composition is 0.001 to 5.0 g / 10 min, or 0.01 to 5.0 g / 10 min, or 0.01 to 10.0 g / 10 min, or 0.1 to 5.0 g / 10 min, or 0.1 to 10.0 g / 10 min, or 0.01 to 4.0 g / 10 min, or 0.01 to 2.5 g / 10 min, or 0. It may also be 1-2.5g / 10 min, or 0.2-5.0g / 10 min, or 0.2-10.0g / 10 min, or 0.5-5.0g / 10 min, or 0.8-5.0g / 10 min, or 0.5-4.0g / 10 min, or 0.8-4.0g / 10 min, or 0.5-2.5g / 10 min, or 0.8-2.5g / 10 min, or 0.5-2.0g / 10 min, or 0.8-2.0g / 10 min.

[0159] In embodiments of this disclosure, the polyethylene composition has a high-load melt index of 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. 21 It has. In further embodiments of the present disclosure, the polyethylene composition has a high load melt index of 55-160 g / 10 min I 21 It has and includes any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the high-load melt index I of the polyethylene composition 21 This may be 55-120g / 10 minutes, or 60-120g / 10 minutes.

[0160] In embodiments of this disclosure, the polyethylene composition has a melt flow ratio I of 35 or more, or greater than 35, or greater than 40, or greater than 45, or greater than 45. 21 / I2 is present. In further embodiments of this disclosure, the polyethylene composition has a melt flow ratio of 35 to 120, I 21 / I2 has any narrow range within this range and any value encompassed within these ranges. For example, in embodiments of the present disclosure, the polyethylene composition has a melt flow ratio I of 35-100, or 40-100, or 45-100, or 35-90, or 40-90, or 45-90. 21 It has / I2.

[0161] In one embodiment of the present disclosure, the polyethylene composition has an inverted or partially inverted comonomer distribution profile as measured by GPC-FTIR.

[0162] In one embodiment of the present disclosure, the polyethylene composition has a substantially flat (or uniform) comonomer distribution profile as measured using GPC-FTIR.

[0163] If comonomer incorporation decreases with increasing molecular weight, as measured by GPC-FTIR, the distribution is described as "normal." If comonomer incorporation is nearly constant with respect to molecular weight, as measured by 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 a copolymer, there is one or more high molecular weight components that have higher comonomer incorporation than one or more low molecular weight components. The term "reverse comonomer distribution" is used herein to mean that the comonomer content of various polymer fractions is not substantially uniform across the molecular weight range of an ethylene copolymer, and that its high molecular weight fraction has a proportionally higher comonomer content (i.e., if comonomer incorporation increases with molecular weight, the distribution is described as "reverse" or "reversed"). Even if comonomer incorporation increases with increasing molecular weight and then decreases, the comonomer distribution is considered "reverse," but may be described as "partially reversed." A partially inverted comonomer distribution will show a peak or maximum value.

[0164] In embodiments of this disclosure, the polyethylene composition CDBI 50 The CDBI of the polyethylene composition is greater than 50% by weight, or greater than 55% by weight, or greater than 60% by weight, or greater than 65% by weight, or greater than 70% by weight, or greater than 75% by weight. In embodiments of the present disclosure, the CDBI of the polyethylene composition is greater than 50% by weight, or greater than 55% by weight, or greater than 60% by weight, or greater than 65% by weight, or greater than 70% by weight. 50 This is 60-98% by weight, or 70-90% by weight, or 75-85% by weight.

[0165] In embodiments of the present disclosure, the upper limit of parts per million (ppm) of hafnium in the polyethylene composition (parts per million of Hf based on the weight of the polyethylene composition) may be about 3.0 ppm, or about 2.5 ppm, or about 2.4 ppm, or about 2.0 ppm, or about 1.5 ppm, or about 1.0 ppm, or about 0.75 ppm, or about 0.5 ppm. In embodiments of the present disclosure, the lower limit of parts per million (ppm) of hafnium in the polyethylene composition may be about 0.0015 ppm, or about 0.0050 ppm, or about 0.0075 ppm, or about 0.010 ppm, or about 0.015 ppm, or about 0.030 ppm, or about 0.050 ppm, or about 0.075 ppm, or about 0.100 ppm, or about 0.150 ppm, or about 0.175 ppm, or about 0.200 ppm.

[0166] In embodiments of this disclosure, the polyethylene composition contains 0.0015 to 2.4 ppm of hafnium, or 0.0050 to 2.4 ppm of hafnium, or 0.0075 to 2.4 ppm of hafnium, or 0.010 to 2.4 ppm of hafnium, or 0.015 to 2.4 ppm of hafnium, or 0.050 to 3.0 ppm of hafnium, or 0.050 to 2.4 ppm of hafnium, or 0.050 to 2.0 ppm of hafnium, or 0.050 to 1.5 ppm of hafnium, or 0.050 to 1.0 ppm It contains m of hafnium, or 0.050 to 0.75 ppm of hafnium, or 0.075 to 2.4 ppm of hafnium, or 0.075 to 2.0 ppm of hafnium, or 0.075 to 1.5 ppm of hafnium, or 0.075 to 1.0 ppm of hafnium, or 0.075 to 0.75 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.

[0167] In embodiments of the present disclosure, the polyethylene composition contains at least 0.0015 ppm of hafnium, or at least 0.005 ppm of hafnium, or at least 0.0075 ppm of hafnium, or at least 0.015 ppm of hafnium, or at least 0.030 ppm of hafnium, or at least 0.050 ppm of hafnium, or at least 0.075 ppm of hafnium, or at least 0.100 ppm of hafnium, or at least 0.125 ppm of hafnium, or at least 0.150 ppm of hafnium, or at least 0.175 ppm of hafnium, or at least 0.200 ppm of hafnium, or at least 0.300 ppm of hafnium, or at least 0.350 ppm of hafnium.

[0168] In one embodiment of the present disclosure, the polyethylene composition includes long-chain branching characterized by a long-chain branching coefficient (LCBF) disclosed herein. In embodiments of the present disclosure, the upper limit of the LCBF of the polyethylene composition may be 0.5000, 0.4000, or 0.3000 (dimensionless). In embodiments of the present disclosure, the lower limit of the LCBF of the polyethylene composition may be 0.0010, 0.0015, 0.0020, 0.0100, 0.0500, or 0.1000 (dimensionless).

[0169] In embodiments of the present disclosure, the LCBF of the polyethylene composition is at least 0.0010, or at least 0.0020, or at least 0.0050, or at least 0.0070, or at least 0.0100, or at least 0.0200, or at least 0.0250.

[0170] In embodiments of this disclosure, the LCBF (dimensionless) of the polyethylene composition may exceed 0.0010, or exceed 0.0050, or exceed 0.0100, or exceed 0.0200.

[0171] 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.

[0172] In one embodiment of this disclosure, a polyethylene composition, Log 10 [I6 / I2] / Log 10[6.48 / 2.16] has a stress index defined as 1.40 or greater. In further embodiments of the present disclosure, the polyethylene composition has a stress index greater than 1.42, greater than 1.45, or greater than 1.50, Log 10 [I6 / I2] / Log 10 It has [6.48 / 2.16].

[0173] In embodiments of this disclosure, the polyethylene composition is Log 10 [I6 / I2] / Log 10 It has a stress index defined as [6.48 / 2.16], which is 1.45 to 1.80, or 1.50 to 1.80, or 1.50 to 1.75.

[0174] In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes above 90°C in a temperature rise elution fraction (TREF) analysis obtained using a CTREF ("CRYSTAF" device) and has an integrated area exceeding 65% by weight. In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes above 90°C in a temperature rise elution fraction (TREF) analysis obtained using a CTREF ("CRYSTAF" device) and has an integrated area exceeding 70% by weight. In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes above 90°C in a temperature rise elution fraction (TREF) analysis obtained using a CTREF ("CRYSTAF" device) and has an integrated area exceeding 75% by weight.

[0175] In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes at 90°C to 98°C in a temperature rise elution fraction (TREF) analysis obtained using a CTREF ("CRYSTAF" device) and has an integrated area exceeding 50% by weight. In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes at 90 to 98°C in a temperature rise elution fraction (TREF) analysis obtained using a CTREF ("CRYSTAF" device) and has an integrated area exceeding 60% by weight. In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes at 90 to 98°C in a temperature rise elution fraction (TREF) analysis obtained using a CTREF ("CRYSTAF" device) and has an integrated area exceeding 70% by weight. In one embodiment of the present disclosure, the polyethylene composition has a fraction that elutes at 90-98°C and has an accumulated area of ​​more than 75% by weight in a temperature rise elution (TREF) analysis obtained using a CTREF apparatus ("CRYSTAF" apparatus).

[0176] Additives may be added to the polyethylene composition during the extrusion or compounding process, but other suitable known methods will be apparent to those skilled in the art. Additives may be added as is, or as part of a separate polymer component (i.e., not the first or second ethylene polymer described above) added during the extrusion or compounding process. Suitable additives known in the art include, but are not limited to, antioxidants, phosphates and phosphonites, nitrones, antacids, UV stabilizers, UV absorbers, metal deactivators, dyes, fillers and reinforcing agents, nanoscale organic or inorganic materials, antistatic agents, lubricants such as calcium stearate, slip additives such as elucimid, and nucleating agents (including nucleating agents, pigments, or other chemicals that may impart a nucleating effect to the polyethylene composition). Additives that may be added optionally are typically added in amounts up to 20% by weight (wt%).

[0177] One or more nucleating agents can be introduced into a polyethylene composition by kneading a mixture of the polymer (usually in the form of powder or pellets) and the nucleating agent. The nucleating agent can be used alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatic agents, UV stabilizers, and fillers. It must be a material that is wetted or absorbed by the polymer, insoluble in the polymer, has a melting point higher than the polymer's melting point, and can be uniformly dispersed in the polymer molten material in the finest possible form (1-10 μm). Compounds known to have nucleating ability in polyolefins include salts of aliphatic monobasic or dibasic acids or arylalkyl acids (such as sodium succinate or aluminum phenylacetate); and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids (such as sodium β-naphthoate). Another compound known to have nucleating ability is sodium benzoate. The nucleating effect can be monitored microscopically by observing the degree of reduction in the size of spherulites formed by the aggregation of crystallites.

[0178] Examples of commercially available nucleating agents that can be added to polyethylene compositions include dibenzylidene sorbital ester (for example, the product sold by Milliken Chemical under the trademark MILLAD® 3988, and the product sold by Ciba Specialty Chemicals under the trademark IRGACLEAR®). Further examples of nucleating agents that can be added to polyethylene compositions include the cyclic organic structure (and its salts, e.g., disodium bicyclo[2.2.1]heptenedicarboxylate) disclosed in U.S. Patent No. 5,981,636; saturated versions of the structure disclosed in U.S. Patent No. 5,981,636 (disclosed in U.S. Patent No. 6,465,551; from Zhao et al. to Milliken); salts of certain cyclic dicarboxylic acids having a hexahydrophthalic acid structure (or "HHPA" structure) disclosed in U.S. Patent No. 6,599,971 (from Dotson et al. to Milliken); and cyclic dicarboxylic acid salts and salts thereof, such as phosphate esters disclosed in U.S. Patent No. 5,342,868 and sold by Asahi Denka Kogyo under the trade names NA-11 and NA-21, and divalent metal salts or metalloid salts (especially calcium salts) of the HHPA structure disclosed in U.S. Patent No. 6,599,971. For clarity, an HHPA structure generally comprises a ring structure having six carbon atoms in the ring and two carboxylic acid groups that are substituents on atoms adjacent to the ring structure. The other four carbon atoms in the ring may be substituted, as disclosed in U.S. Patent No. 6,599,971. One example is calcium 1,2-cyclohexanedicarboxylate (CAS Registry No. 491589-22-1). Further examples of nucleating agents that can be added to polyethylene compositions are disclosed in International Publication Nos. 2015 / 042561, 2015 / 042563, 2015 / 042562, and 2011 / 050042.

[0179] Many of the nucleating agents mentioned above can be difficult to mix with the polyethylene composition on which they form nucleation. To mitigate this problem, it is known that dispersing agents such as zinc stearate are used.

[0180] In one embodiment of the present disclosure, the nucleating agent is well dispersed in the polyethylene composition.

[0181] In one embodiment of the present disclosure, since the amount of nucleating agent used is relatively small (5 to 3000 ppm by weight, based on the weight of the polyethylene composition), it will be understood by those skilled in the art that some care must be taken to ensure that the nucleating agent is well dispersed. In one embodiment of the present disclosure, the nucleating agent is added to the polyethylene composition in a finely divided form (less than 50 microns, particularly less than 10 microns) to facilitate mixing. This type of “physical blend” (i.e., a mixture of the nucleating agent and resin in solid form) may be preferred in some embodiments to using a “masterbatch” of the nucleating agent (wherein the term “masterbatch” refers to embodiments in which the additive (in this case, the nucleating agent) is first melt-mixed with a small amount of polyethylene composition resin, and then the “masterbatch” is melt-mixed with the remaining bulk of the polyethylene composition resin).

[0182] In one embodiment of the present disclosure, additives such as nucleating agents may be added to the polyethylene composition in a “masterbatch” manner, where the term “masterbatch” refers to an embodiment in which the additive (e.g., nucleating agent) is first melt-mixed with a small amount of polyethylene composition, and then the “masterbatch” is melt-mixed with the remaining bulk of the polyethylene composition.

[0183] In one embodiment of the present disclosure, the polyethylene composition further comprises a nucleating agent or a mixture of nucleating agents.

[0184] <Biaxially oriented film> In one embodiment, the biaxially oriented film or film structure is a BOPE film or film structure.

[0185] In one embodiment of the present disclosure, the biaxially oriented polyethylene film or biaxially oriented polyethylene film structure is 0.940 g / cm² 3A polyethylene composition having the above density is provided, and is prepared and described in accordance with this disclosure.

[0186] In one embodiment of this disclosure, the biaxially oriented polyethylene film or biaxially oriented polyethylene film structure comprises the polyethylene composition described herein.

[0187] A biaxially oriented polyethylene (BOPE) film or film structure can be manufactured using a tenter frame process in one embodiment of the present disclosure.

[0188] The tenter frame process is commonly used to prepare biaxially oriented films and is suitable for use in embodiments of the present disclosure. The tenter frame process is well known to those skilled in the art of film manufacturing. This process begins with an extruder equipped with slot dies for forming a sheet or film. For convenience, this extruded sheet or film may be referred to as the “base film” or “base film structure” or “base structure.” Once the base structure is quenched on cooling rolls, it is reheated, and mechanical direction (MD) stretching or mechanical direction orientation (MDO) is achieved by pulling the base structure using several closely spaced rolls rotating at a gradually increasing surface speed. Following the MD stretching, clips (mounted on a chain) grasp the ends of the moving sheet (or film, or web) and transport it to an oven. Inside the oven, the ends of the base structure are pulled apart, widening the sheet and thereby providing transverse orientation (TDO). This orientation / stretching thins the film structure in proportion to the orientation ratio or stretching ratio. For example, to prepare a 1-mil BOPE film with a stretch ratio of 5:1 in the machine direction (MD) and 8:1 in the transverse direction (TD), the process may be started using a 40-mil thick film or sheet.

[0189] In embodiments of the present disclosure, the stretch ratio in the machine direction (MD) may be in the range of about 5:1 to about 9:1, and the stretch ratio in the transverse direction (TD) may be in the range of about 7:1 to about 12:1. In other embodiments of the present disclosure, the stretch ratio in the machine direction (MD) may be in the range of about 3:1 to about 12:1, and the stretch ratio in the transverse direction (TD) may be in the range of about 3:1 to about 12:1. In yet another embodiment of the present disclosure, the stretch ratio in the machine direction (MD) may be in the range of about 5:1 to about 12:1, and the stretch ratio in the transverse direction (TD) may be in the range of about 5:1 to about 12:1. In yet another embodiment of the present disclosure, the stretch ratio in the machine direction (MD) may be in the range of about 3:1 to about 10:1, and the stretch ratio in the transverse direction (TD) may be in the range of about 3:1 to about 10:1.

[0190] Details of the biaxial orientation process are described in the textbook "Film Processing Advances" (2014) by Kanai T. et al., Hanser Publishers. However, generally, the sequential biaxial orientation process includes: casting and extruding a relatively thick base film structure from a slot die and then cooling it on a cooling roll (or using a water bath); stretching the base film structure in the machine direction using heated rollers that rotate at gradually increasing speeds; stretching the film structure laterally by pulling each end of the film structure with clips attached to the ends of the film structure, where the clips move away as the film is pulled forward, pulling the gripped ends of the film laterally (i.e., the stretching is performed laterally); passing the film structure through an oven to anneal it; optionally surface-treating the film structure; cutting off the unstretched ends of the film structure held by the clips; and winding the film structure.

[0191] In embodiments of this disclosure, sequential biaxial stretching is used, but sequential biaxial stretching can cause film quality problems in some embodiments. For example, in some embodiments, the optics of the film or multilayer film structure may be impaired. Therefore, in certain embodiments, an alternative unit operation involving simultaneous stretching in the mechanical direction / transverse direction in a single process step may be preferred. During simultaneous stretching, the base film may be held by tenter clips (as described above) and suspended while being stretched in both the MD and TD directions.

[0192] In one embodiment of the present disclosure, the biaxially oriented film or film structure comprises the polyethylene composition described herein.

[0193] In one embodiment, a biaxially oriented film or film structure is prepared using 60 to 100% by weight of the polyethylene composition described herein (based on the weight of the polymer material used in the film or film structure). In one embodiment, a biaxially oriented film or film structure is prepared using 70 to 90% by weight of the polyethylene composition described herein (based on the weight of the polymer material used in the film or film structure). In one embodiment, a biaxially oriented film or film structure is prepared using 80 to 95% by weight of the polyethylene composition described herein (based on the weight of the polymer material used in the film or film structure).

[0194] In one embodiment, an "all-polyethylene" biaxially oriented film or film structure is prepared using at least 90% by weight of the polyethylene composition described herein (based on the weight of the polymer used in the film or film structure). In one embodiment, an "all-polyethylene" biaxially oriented film or film structure is prepared using at least 95% by weight of the polyethylene composition described herein (based on the weight of the polymer used in the film or film structure). In one embodiment, an "all-polyethylene" biaxially oriented film or film structure is prepared using at least 99% by weight of the polyethylene composition described herein (based on the weight of the polymer used in the film or film structure). In one embodiment, an "all-polyethylene" biaxially oriented film or film structure is prepared using 100% by weight of the polyethylene composition described herein (based on the weight of the polymer used in the film or film structure).

[0195] In one embodiment, a biaxially oriented film or film structure is prepared using 60-100% by weight (based on the weight of the polymer used in the film or film structure) of the polyethylene composition described herein, and the remaining polymer(s) used to prepare the biaxially oriented film or film structure is a different polyethylene composition. In another embodiment, a biaxially oriented film or film structure is prepared using 70-90% by weight (based on the weight of the polymer used in the film or film structure) of the polyethylene composition described herein, and the remaining polymer(s) used to prepare the biaxially oriented film or film structure is a different polyethylene composition. In yet another embodiment, a biaxially oriented film or film structure is prepared using 80-95% by weight (based on the weight of the polymer used in the film or film structure) of the polyethylene composition described herein, and the remaining polymer(s) used to prepare the biaxially oriented film or film structure is a different polyethylene composition. While we do not wish to be bound by theory, preparing a biaxially oriented film or film structure using only polyethylene compositions allows for easier recycling of the film compared to a biaxially oriented film or film structure made from a mixture of different types of polymers.

[0196] The use of polymer blends is known in the art of preparing biaxially oriented films or film structures, and this is also intended in certain embodiments of the present disclosure. Accordingly, in embodiments of the present disclosure, a biaxially oriented film or film structure is prepared from a polymer blend comprising at least 50% by weight, or at least 60% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight (based on the total weight of polymer materials used to make the polymer blend) of the polyethylene composition described herein.

[0197] In embodiments of the present disclosure, a layer of a biaxially oriented film or film structure is prepared from a polymer blend comprising at least 50% by weight, or at least 60% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight (based on the total weight of the polymer material used to produce the layer) of the polyethylene composition described herein.

[0198] Some non-limiting examples of other polymers suitable for use in blends with the polyethylene compositions described herein in embodiments of this disclosure include: linear low-density polyethylene (LLDPE); medium-density polyethylene (MDPE); high-density polyethylene (HDPE); very low-density polyethylene (VLDPE) or very low-density polyethylene (ULDPE) containing elastomers and plastomers; and high-pressure low-density polyethylene (HPLDPE) prepared by free-radical polymerization of ethylene.

[0199] In embodiments of this disclosure, layers of a biaxially oriented film or film structure are prepared from a polymer blend comprising: A) at least 50% by weight, or at least 60% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight of the polyethylene composition described herein (based on the total weight of the polymer material used to make the layer); and B) 50% by weight or less, or 40% by weight or less, or 25% by weight or less, or 10% by weight or less, or 5% by weight or less, or 1% by weight or less (based on the total weight of the polymer material used to make the layer) of a polymer selected from the group consisting of linear low-density polyethylene (LLDPE); medium-density polyethylene (MDPE); high-density polyethylene (HDPE); very low-density polyethylene (VLDPE) or very low-density polyethylene (ULDPE); and high-pressure low-density polyethylene (HPLDPE) prepared by free radical polymerization of ethylene.

[0200] In embodiments of this disclosure, layers of a biaxially oriented film or film structure are prepared from a polymer blend comprising: A) at least 50% by weight, or at least 60% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight of the polyethylene composition described herein (based on the total weight of the polymer material used to make the layer); and B) 50% by weight or less, or 40% by weight or less, or 25% by weight or less, or 10% by weight or less, or 5% by weight or less, or 1% by weight or less of a polymer selected from the group consisting of linear low-density polyethylene (LLDPE); medium-density polyethylene (MDPE); high-density polyethylene (HDPE); very low-density polyethylene (VLDPE); and mixtures thereof (based on the total weight of the polymer material used to make the layer).

[0201] In embodiments of this disclosure, layers of a biaxially oriented film or film structure are prepared from a polymer blend comprising: A) at least 50% by weight, or at least 60% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight, or at least 99% by weight of the polyethylene composition described herein (based on the total weight of the polymer material used to make the layer); and B) 50% by weight or less, or 40% by weight or less, or 25% by weight or less, or 10% by weight or less, or 5% by weight or less, or 1% by weight or less of a polymer selected from the group consisting of linear low-density polyethylene (LLDPE); medium-density polyethylene (MDPE); high-density polyethylene (HDPE); and very low-density polyethylene (VLDPE) (based on the total weight of the polymer material used to make the layer).

[0202] In embodiments of this disclosure, the LLDPE used in polymer blends with the polyethylene compositions described herein has a melt index (I2) of 0.1 to 10 g / 10 min or 0.9 to 2.3 g / 10 min, and a melt index of approximately 0.910 to approximately 0.935 g / cm³. 3 It has a density of .

[0203] In embodiments of this disclosure, the VLPDE used in polymer blends with the polyethylene compositions described herein has a melt index (I2) of 0.1 to 10 g / 10 min or 0.9 to 2.3 g / 10 min, and a melt index of approximately 0.880 to approximately 0.910 g / cm³. 3 It has a density of .

[0204] In embodiments of this disclosure, the MDPE used in polymer blends with the polyethylene compositions described herein has a melt index (I2) of 0.1 to 10 g / 10 min or 0.9 to 2.3 g / 10 min, and a melt index of approximately 0.936 to approximately 0.949 g / cm³. 3 It has a density of .

[0205] In embodiments of this disclosure, the HDPE used in polymer blends with the polyethylene compositions described herein has a melt index (I2) of 0.1 to 10 g / 10 min or 0.4 to 0.9 g / 10 min and at least about 0.950 g / cm³ 3 It has a density of .

[0206] In one embodiment of this disclosure, the HPLDPE used in the polymer blend with the polyethylene composition described herein has a melt index (I2) of 0.1 to 10 g / 10 min and approximately 0.92 to approximately 0.94 g / cm³ 3 It has a density of .

[0207] In the field of the art of preparing biaxially oriented films, it is known to use multilayer films or film structures as (unstretched) starting films. These starting films are relatively thick before stretching and are often referred to as "sheets" rather than films. For convenience, such unstretched multilayer sheets may be referred to herein as "base films," "base film structures," or "base structures."

[0208] In one embodiment of the present disclosure, a suitable base film structure comprises at least 60% by weight, or at least 70% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or 100% by weight of the polyethylene composition described herein (based on the total weight of the polymer used to produce the base film structure).

[0209] In one embodiment of the present disclosure, the biaxially oriented film or film structure comprises at least 60% by weight, or at least 70% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or 100% by weight of the polyethylene composition described herein (based on the total weight of the polymer used to produce the biaxially oriented film or film structure).

[0210] In one embodiment of the present disclosure, the polyethylene composition described herein is used as a “core” layer in a suitable base film structure (i.e., as an inner layer in a multilayer base film structure). Examples of polymers that can be used to prepare other layers in a suitable base film structure in embodiments of the present disclosure include LLDPE, MDPE, HDPE, VLPDE, and HPLDPE, which include embodiments of LLDPE, MDPE, HDPE, VLPDE, and HPLDPE described above.

[0211] In one embodiment of the present disclosure, the multilayer base film structure comprises at least three layers, including two skin layers (i.e., layers on each outer surface of the base film structure) and one or more core layers.

[0212] In one embodiment of this disclosure, as disclosed in the published U.S. Patent No. 9,676,169, one skin layer may be made from HDPE and the other skin layer is a seal layer.

[0213] In one embodiment of the present disclosure, the sealing layer may include linear low-density polyethylene, LLDPE (for example, LLDPE made with a so-called metallocene catalyst, as is well known to those skilled in the art), a plastomer, an elastomer, or a blend thereof.

[0214] In one embodiment, a plastomer containing polymerized ethylene and 1-octene monomer (as well as blends thereof with LLDPE, HDPE, and / or HPLDPE) can also be used as the sealing layer.

[0215] In one embodiment of this disclosure, it is also intended that a plastomer (or a polymer blend thereof) be used for both skin layers of the BOPE film.

[0216] While I don't want to be constrained by theory, using a plastomer in the skin layer may improve the optical properties of the BOPE film.

[0217] In one embodiment of the present disclosure, the BOPE film has a core layer comprising the polyethylene composition described herein, and both skin layers comprise a plastomer comprising polymerized ethylene and 1-octene monomer.

[0218] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises a core layer containing a polyethylene composition prepared as described herein, and two skin layers, both of which also contain the polyethylene composition described herein.

[0219] In one embodiment of the present disclosure, the biaxially oriented film or film structure comprises at least three layers, the at least one of which comprises the polyethylene composition described herein.

[0220] In one embodiment of the present disclosure, the biaxially oriented film or film structure comprises at least three layers, each of which comprises a polyethylene composition as described herein.

[0221] In one embodiment of the present disclosure, the biaxially oriented film or film structure comprises at least three adjacent layers, each of which comprises a polyethylene composition as described herein.

[0222] In one embodiment of the present disclosure, the biaxially oriented film or film structure comprises at least three layers, each of which comprises a polyethylene composition as described herein.

[0223] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, at least one of which comprises at least 50% by weight (based on the total weight of the polymer material used in that layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, at least one of which comprises at least 75% by weight (based on the total weight of the polymer material used in that layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, at least one of which comprises at least 95% by weight (based on the total weight of the polymer material used in that layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, at least one of which comprises at least 99% by weight (based on the total weight of the polymer material used in that layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, at least one of which comprises 100% by weight (based on the total weight of the polymer material used in that layer) of the polyethylene composition specified herein.

[0224] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising at least 50% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising at least 75% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising at least 95% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising at least 99% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising 100% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein.

[0225] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each layer comprising at least 50% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each layer comprising at least 75% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each layer comprising at least 95% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each layer comprising at least 99% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each layer comprising 100% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein.

[0226] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each of which contains at least 50% by weight (based on the total weight of polymer material used in each adjacent layer) of the polyethylene composition described herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each of which contains at least 75% by weight (based on the total weight of polymer material used in each adjacent layer) of the polyethylene composition described herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each of which contains at least 95% by weight (based on the total weight of polymer material used in each adjacent layer) of the polyethylene composition described herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each of which contains at least 99% by weight (based on the total weight of polymer material used in each adjacent layer) of the polyethylene composition described herein. In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each of which comprises 100% by weight (based on the total weight of the polymer material used in each adjacent layer) of the polyethylene composition described herein.

[0227] In one embodiment, the biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer contains the polyethylene composition described herein. In one embodiment, the biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer contains at least 50% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition described herein. In one embodiment, the biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer contains at least 75% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition described herein. In one embodiment, a biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer contains at least 95% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In another embodiment, a biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer contains at least 99% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition specified herein. In one embodiment, a biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer comprises 100% by weight (based on the total weight of the polymer material used in each layer) of the polyethylene composition described herein.

[0228] In one embodiment, the biaxially oriented film or film structure includes a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein the core layer constitutes at least 50% by weight of the total weight of the biaxially oriented film or film structure.

[0229] In one embodiment, the biaxially oriented film or film structure includes a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein the core layer constitutes at least 60% by weight of the total weight of the biaxially oriented film or film structure.

[0230] In one embodiment, the biaxially oriented film or film structure includes a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein the core layer constitutes at least 70% by weight of the total weight of the biaxially oriented film or film structure.

[0231] In one embodiment, the biaxially oriented film or film structure includes a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein the core layer constitutes at least 80% by weight of the total weight of the biaxially oriented film or film structure.

[0232] In one embodiment, the biaxially oriented film or film structure includes a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein the core layer constitutes at least 90% by weight of the total weight of the biaxially oriented film or film structure.

[0233] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising a polymer blend, the polymer blend comprising A) 50 to 99% by weight of the polyethylene composition described herein, and B) 50 to 1% by weight of a different polymer selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0234] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three layers, each layer comprising a polymer blend, the polymer blend comprising A) 75 to 99% by weight of the polyethylene composition described herein, and B) 25 to 1% by weight of a different polymer selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0235] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least several layers, each of which comprises three adjacent layers comprising a polymer blend, the polymer blend comprising A) 50 to 99% by weight of the polyethylene composition described herein, and B) 50 to 1% by weight of different polymers selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0236] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least several layers, each of which comprises three adjacent layers comprising a polymer blend, the polymer blend comprising A) 75 to 99% by weight of the polyethylene composition described herein, and B) 25 to 1% by weight of different polymers selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0237] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer, wherein each layer of the core layer, the first skin layer, and the second skin layer comprises a polymer blend, the polymer blend comprising A) 50 to 99% by weight of the polyethylene composition described herein, and B) 50 to 1% by weight of different polymers selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0238] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer, wherein each layer of the core layer, the first skin layer, and the second skin layer comprises a polymer blend, the polymer blend comprising A) 50 to 99% by weight of the polyethylene composition described herein, and B) 50 to 1% by weight of different polymers selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0239] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer, wherein each layer of the core layer, the first skin layer, and the second skin layer comprises a polymer blend, the polymer blend comprising A) 75 to 99% by weight of the polyethylene composition described herein, and B) 25 to 1% by weight of different polymers selected from the group consisting of LLDPE, MDPE, HDPE, VLPDE, HPLDPE and mixtures thereof.

[0240] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three layers has a haze value of 20% or less, or less than 20%, or 15% or less, or less than 15%, or 10% or less, or less than 10%, or 7.5% or less.

[0241] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three layers, each layer comprising a polyethylene composition as described herein, has a haze value of 20% or less, or less than 20%, or 15% or less, or less than 15%, or 10% or less, or less than 10%, or 7.5% or less, or less than 7.5%.

[0242] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three layers, wherein three adjacent layers comprising the polyethylene composition described herein, has a haze value of 20% or less, or less than 20%, or 15% or less, or less than 15%, or 10% or less, or less than 10%, or 7.5% or less, or less than 7.5%.

[0243] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three adjacent layers, each layer comprising the polyethylene composition described herein, has a haze value of 20% or less, or less than 20%, or 15% or less, or less than 15%, or 10% or less, or less than 10%, or 7.5% or less.

[0244] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three layers has a transparency value of 80% or more, or greater than 80%, or greater than 85%, or greater than 85%, or greater than 90%, or greater than 90%, or greater than 95%, or greater than 95%.

[0245] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three layers, each layer comprising a polyethylene composition as described herein, has a transparency value of 80% or more, or more than 80%, or 85% or more, or more than 85%, or 90% or more, or more than 90%, or more than 95%, or more than 95%.

[0246] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three layers, wherein three adjacent layers comprising the polyethylene composition described herein, has a transparency value of 80% or more, or greater than 80%, or greater than 85%, or greater than 85%, or greater than 90%, or greater than 90%, or greater than 95%, or greater than 95%.

[0247] In embodiments of the present disclosure, a biaxially oriented film or film structure comprising at least three adjacent layers, each layer comprising a polyethylene composition as described herein, has a transparency value of 80% or more, or more than 80%, or 85% or more, or more than 85%, or 90% or more, or more than 90%, or more than 95%, or more than 95%.

[0248] In one embodiment, a biaxially oriented film or film structure comprising a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer comprises the polyethylene composition described herein and has a haze value of 20% or less, or less than 20%, or 15% or less, or less than 15%, or 10% or less, or less than 10%, or 7.5% or less, or less than 7.5%.

[0249] In one embodiment, a biaxially oriented film or film structure comprising a core layer, a first skin layer adjacent to the first side of the core layer, and a second skin layer adjacent to the second side of the core layer, wherein each of the core layer, the first skin layer, and the second skin layer comprises the polyethylene composition described herein, and has a transparency value of 80% or more, or more than 80%, or 85% or more, or more than 85%, or 90% or more, or more than 90%, or more than 95%, or more than 95%.

[0250] One embodiment of the present disclosure is a multilayer film structure comprising at least five layers, comprising: a core layer comprising the polyethylene composition described herein; two outer skin layers made from a plastomer; and two “adjacent skin (layer)” layers made from a blend of the plastomer and polyethylene of a higher density than the plastomer.

[0251] It is known that a layer of "barrier resin" is used to improve the barrier properties of BOPE films. Not limited examples of suitable barrier resins include ethylene vinyl alcohol (EVOH) and polyamides. When using a barrier resin in a BOPE film, suitable tie layers can also be used between the barrier layer and the polyethylene layer to improve the fit of the layers (e.g., the adhesion between the layers). For an example of a tie layer suitable for use in embodiments of this disclosure, see U.S. Patent Application Publication 2020 / 0369014.

[0252] In one embodiment of the present disclosure, the surface of a biaxially oriented film or film structure is metallized.

[0253] In one embodiment of the present disclosure, the surface of a biaxially oriented film or film structure is metallized after surface treatment.

[0254] In the metallization process, a biaxially oriented film can be placed in a vacuum chamber, and physical vapor deposition (PVD) metallization can be performed using a metal source such as the metal itself or a metal oxide. In the PVD metallization process, a metal layer is added 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 on the surface of the film or film structure. Examples of metals that can be added to a biaxially oriented film using vapor deposition metallization include aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, silver, nickel, copper, zinc, gold, palladium, or mixtures thereof. In embodiments of this disclosure, the thickness of the metallized layer (i.e., the deposited metal layer) can be 100 to 5000 angstroms, or 300 to 3000 angstroms.

[0255] In one embodiment of the present disclosure, the surface of a biaxially oriented film or film structure is metallized by physical vapor deposition (PVD) metallization with aluminum.

[0256] The polymers used in this disclosure (including polyethylene compositions prepared and described herein) contain, in certain embodiments, antioxidants (such as hindered phenols, phosphites, or blends thereof) in conventional amounts, 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 certain embodiments include anti-blocking agents, slip agents, and nucleating agents (such as those disclosed in U.S. Patent No. 9,676,169). Zinc glycerolate is also intended to be used as an optional nucleating agent for use in certain embodiments of this disclosure (Note: Zinc glycerolate nucleating agents are commercially available under the trademark IRGASTAB® 287).

[0257] In one embodiment of the present disclosure, the surface of a biaxially oriented film or film structure is surface-treated. While we do not wish to be bound by theory, surface treatment can make the surface more suitable for, or more receptive to, metallization, coating, printing inks, adhesives, and / or lamination.

[0258] In embodiments of this disclosure, the surface of a biaxially oriented film or film structure is surface-treated by corona discharge radiation, flame or polarized flame (polirized flame), plasma, or chemical treatment.

[0259] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film, the process comprising: (a) extruding a polyethylene composition onto a base film; (b) stretching the base film in the machine direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film transversely to a stretch ratio of 3:1 to 12:1, wherein (a) and (b) are carried out in any order or simultaneously.

[0260] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film structure, the process comprising: (a) co-extruding a polyethylene composition into a base film structure comprising at least three layers; (b) stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (a) and (b) are carried out in any order or simultaneously.

[0261] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film structure, the process comprising: (a) co-extruding a polyethylene composition into a base film structure having at least three adjacent layers; (b) stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (a) and (b) are carried out in any order or simultaneously.

[0262] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film structure, the process comprising: (a) co-extruding a polyethylene composition into a base film structure comprising a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer; (b) stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (b) and (c) are carried out in any order or simultaneously.

[0263] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film, the process comprising: (a) extruding a polymer blend comprising at least 75% by weight of a polyethylene composition onto a base film; (b) stretching the base film in the mechanical direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (b) and (c) are carried out in any order or simultaneously.

[0264] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film structure, the process comprising: (a) co-extruding a polymer blend comprising at least 75% by weight of a polyethylene composition into a base film structure comprising at least three layers; (b) stretching the base film structure in the mechanical direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (b) and (c) are carried out in any order or simultaneously.

[0265] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film structure, the process comprising: (a) co-extruding a polymer blend comprising at least 75% by weight of a polyethylene composition into a base film structure comprising at least three adjacent layers; (b) stretching the base film structure in the mechanical direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (b) and (c) are carried out in any order or simultaneously.

[0266] One embodiment of the present disclosure is a process for preparing a biaxially oriented polyethylene film structure, the process comprising: (a) co-extruding a polymer blend comprising at least 75% by weight of a polyethylene composition into a base film structure comprising a core layer, a first skin layer adjacent to a first side of the core layer, and a second skin layer adjacent to a second side of the core layer; (b) stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 12:1; and (c) stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1, wherein (b) and (c) are carried out in any order or simultaneously.

[0267] Biaxially oriented films prepared according to this disclosure may be suitable for a wide variety of packaging applications. In one embodiment, the biaxially oriented film can be used in a laminate structure, for example, when laminated to a sealant web made from lower-density polyethylene, it can be used as a printed web. This type of laminate structure is more easily recyclable than conventional laminate structures that include a layer of polyester or polypropylene laminated to a layer of polyethylene.

[0268] The following embodiments are provided for the purpose of illustrating selected embodiments of the present disclosure, and it should be understood that the embodiments provided are not intended to limit the scope of the presented claims. [Examples]

[0269] <Methods for Characterizing and Testing Polymers> Prior to testing, each polymer test specimen was conditioned at 23±2°C and 50±10% relative humidity for at least 24 hours, and the subsequent testing was carried out at 23±2°C and 50±10% relative humidity. In this specification, the term "ASTM conditions" refers to a laboratory maintained at 23±2°C and 50±10% relative humidity, where the test specimens were conditioned for at least 24 hours prior to testing. ASTM refers to the American Society for Testing and Materials.

[0270] <density> The polymer density was determined using ASTM D792-13 (November 1, 2013).

[0271] <Melt Index> The melt index of the polymer was determined using ASTM D1238 (August 1, 2013). Melt index: I2, I6, I 10 , and I 21 These were measured at 190°C using weights of 2.16 kg, 6.48 kg, 10 kg, and 21.6 kg, respectively. In this specification, the term "stress index" or its acronym "S.Ex." is defined by the following relationship: S.Ex.=log(I6 / I2) / log(6480 / 2160) (In the formula, I6 and I2 are melt flow ratios measured at 190°C using loads of 6.48 kg and 2.16 kg, respectively). In this disclosure, the melt index is expressed in units of g / 10 min, g / 10 min, dg / min, or dg / min, and these units are equivalent.

[0272] <Neutron activation (elemental analysis)> Using neutron activation analysis (NAA), catalyst metal residues in polymers were determined as follows: Polymer samples were packed into radiation vials (made of ultra-high-purity polyethylene, internal capacity 7 mL), and the sample weight was recorded. Using a pneumatic transfer system, the samples were placed inside a SLOWPOKE® reactor (Atomic Energy of Canada Limited, Ottawa, Ontario, Canada) and irradiated for 30-600 seconds for elements with short half-lives (e.g., Ti, V, Al, Mg, and Cl) or 3-5 hours for elements with long half-lives (e.g., Zr, Hf, Cr, Fe, and Ni). The average thermal neutron flux inside the reactor was 5 × 10⁻¹⁶. 11 / cm 2The irradiation time was / s. After irradiation, the sample was removed from the reactor and aged to decay its radioactivity; elements with short half-lives were aged for 300 seconds, and elements with long half-lives were aged for several days. After aging, the gamma-ray spectrum of the sample was recorded using a germanium semiconductor gamma-ray detector (Ortec model GEM55185, Advanced Measurement Technology Inc., Oak Ridge, Tennessee, USA) and a multi-channel analyzer (Ortec model DSPEC Pro). The amount of each element in the sample was calculated from the gamma-ray spectrum and recorded as parts per million (ppm) relative to the total weight of the polymer sample. The NAA system was calibrated using a Specpure standard (1000 ppm solution of the desired element (purity over 99%)). 1 mL of the solution (of the target element) was pipetteed onto a 15 mm × 800 mm rectangular paper filter and air-dried. The filter paper was then placed in a 1.4 mL polyethylene irradiation vial and analyzed with the NAA system. Use the standard to determine the sensitivity (counts / μg) of the NAA procedure.

[0273] <Gel Permeation Chromatography (GPC)> Polyethylene composition sample (polymer) solutions (1-3 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150°C for 4 hours. To stabilize the polymer against oxidative degradation, an antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture. The BHT concentration was 250 ppm. The polymer solutions were chromatographed using a PL220 high-temperature chromatography unit equipped with four Shodex columns (HT803, HT804, HT805, and HT806), with TCB as the mobile phase, at a flow rate of 1.0 mL / min and 140°C, using a differential refractive index (DRI) as the concentration detector. To protect the GPC columns from oxidative degradation, BHT was added to the mobile phase at a concentration of 250 ppm. The sample injection volume was 200 μL. The GPC columns were calibrated with narrow-distribution polystyrene standards. As described in ASTM Standard Test Method D6474-12 (December 2012), polystyrene molecular weight was converted to polyethylene molecular weight using the Mark-Houwink formula. The raw GPC data was processed with CIRRUS® GPC software to obtain the molar mass average (M n M w M z ) and molar mass distribution (e.g., polydispersity M w / M n ) was generated. In the field of polyethylene technology, the commonly used term equivalent to GPC is SEC, or size exclusion chromatography.

[0274] <Triple detection size exclusion chromatography (3D-SEC)> Polyethylene composition sample (polymer) solutions (1-3 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150°C for 4 hours. To stabilize the polymer against oxidative degradation, an antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture. The BHT concentration was 250 ppm. The sample solutions were chromatographed at 140°C using a PL 220 high-temperature chromatography unit equipped with a differential refractive index (DRI) detector, dual-angle light scattering detectors (15° and 90°), and a differential viscometer. The SEC columns used were either four Shodex columns (HT803, HT804, HT805, and HT806) or four PL Mixed ALS or BLS columns. TCB was used as the mobile phase at a flow rate of 1.0 mL / min, and BHT was added to the mobile phase at a concentration of 250 ppm to protect the SEC column from oxidative degradation. The sample injection volume was 200 μL. Raw SEC data was processed with CIRRUS GPC software to calculate the absolute molar mass and intrinsic viscosity ([η]). The term "absolute" molar mass was used to distinguish between the absolute molar mass determined by 3D-SEC and the molar mass determined by conventional SEC. Viscosity-average molar mass (M) determined by 3D-SEC v The long-chain branching coefficient (LCBF) was determined using the following formula.

[0275] <gpc-ftir> Polyethylene composition (polymer) solutions (2-4 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150°C for 4 hours. An antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. The sample solutions were chromatographed using TCB as the mobile phase at a flow rate of 1.0 mL / min and 140°C in a WATERS GPC 150C chromatography unit equipped with four Shodex columns (HT803, HT804, HT805, HT806). As a detection system, an FTIR spectrometer and a heated FTIR flow-through cell were connected to the chromatography unit via a heated transfer line. BHT was added to the mobile phase at a concentration of 250 ppm to protect the SEC columns from oxidative degradation. The sample injection volume was 300 μL. Raw FTIR spectra were processed with OPUS FTIR software, and polymer concentrations and methyl content were calculated in real time using the chemometric software (PLS technique) associated with OPUS. Polymer concentrations and methyl content were then obtained and baseline-corrected using CIRRUS GPC software. SEC columns were calibrated with narrow-distribution polystyrene standards. Polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink formula, as described in ASTM standard test method D6474. Comonomer content was calculated based on the polymer concentrations and methyl content predicted by the PLS technique, as described in Paul J. DesLauriers, Polymer 43, pp. 159–170 (2002); incorporated herein by reference.

[0276] <Short-chain branching: GPC-FTIR> The number of short-chain branches per 1000 carbon atoms is measured for copolymer fractions with different molecular weights. When plotted on a semi-logarithmic scale graph, the slope line (with the horizontal X-axis representing low molecular weight fractions to high molecular weight fractions and the vertical Y-axis representing the number of short-chain branches) represents the distribution of short-chain branches for fractions with different molecular weights, as determined by Fourier transform infrared (FTIR) spectroscopy. The GPC-FTIR method measures the total methyl content, including methyl groups located at the ends of each polymer chain, i.e., methyl-terminated groups. Therefore, raw GPC-FTIR data needs to be corrected by subtracting the contribution from the methyl-terminated groups. More specifically, raw GPC-FTIR data overestimates the amount of short-chain branches (SCBs), and this overestimation increases as molecular weight (M) decreases. In this disclosure, raw GPC-FTIR data were corrected using a 2-methyl correction. For a given molecular weight (M), the methyl-terminated group (N) E The number of ) is given by the following formula; N E =28000 / M is used for the calculation, and N E (M-dependent) was subtracted from the raw GPC-FTIR data to create SCB / 1000C (2-methyl corrected) GPC-FTIR data.

[0277] <Unsaturated content> The amount of unsaturated groups, i.e., double bonds, in the polyethylene compositions was determined according to ASTM D3124-98 (vinylidene unsaturated, published March 2011) and ASTM D6248-98 (vinyl and trans unsaturated, published July 2012). Ethylene interpolymer samples were first subjected to carbon disulfide extraction to remove any additives that may interfere with the analysis; b) the samples (pellets, films, or granules) were pressed to form plaques of uniform thickness (0.5 mm); and c) the plaques were analyzed by FTIR.

[0278] <Comonomer content: Fourier transform infrared (FTIR) spectroscopy> The amount of comonomers in the polyethylene composition was determined by FTIR and reported as the short-chain branch (SCB) content with dimensions of CH3# / 1000C (number of methyl branches per 1000 carbon atoms). This test was completed using compression-molded polymer plaques and a Thermo-Nicolet 750 Magna-IR spectrophotometer according to ASTM D6645-01 (2001). The polymer plaques were prepared using a compression molding apparatus (Wabash-Genesis series press) according to ASTM D4703-16 (April 2016).

[0279] <Differential Scanning Calorimetry (DSC)> DSC testing was performed according to ASTM D3418. This analysis is performed by exposing polymer samples (5-10 mg prepared in an aluminum pan) and a reference substance (an empty aluminum pan) to a constant rate of temperature change in a DSC cell. The actual temperatures of the sample and reference substance are monitored by the instrument as the sample temperature rises or falls linearly over time. If the sample undergoes a transition, reaction, or transformation, the rate of its temperature change will differ from that of the reference substance. The instrument (TA Instruments Q2000) was first calibrated with indium. After calibration, the polymer test specimen was equilibrated at 0°C, the temperature was raised to 200°C at a heating rate of 10°C / min, the molten material was then held isothermally at 200°C for 5 minutes, the molten material was then cooled to 0°C at a cooling rate of 10°C / min and held at 0°C for 5 minutes, and then the test specimen was heated to 200°C at a heating rate of 10°C / min. Next, the temperature difference between the sample and the reference material (DT = Treference - Tsample) was plotted against the sample temperature to create a differential thermogram. From this plot, the melting peak temperature (°C), enthalpy of melting (J / g), and degree of crystallinity (%) were determined.

[0280] <Dynamic mechanical analysis (DMA)> Vibrational shear measurements were performed at small strain amplitudes, and linear viscoelastic functions were obtained in a frequency range of 0.02 to 126 rad / s at 190°C in an N2 atmosphere, with a strain amplitude of 10%, and 5 points per 10 points. Frequency sweep experiments were performed using a TA Instruments DHR3 stress-controlled rheometer with a cone angle of 5°, a truncated head of 137 μm, and a conical plate shape with a diameter of 25 mm. In these experiments, sinusoidal strain waves were applied, and the stress response was analyzed in terms of linear viscoelastic functions. The zero shear rate viscosity (η0) based on the DMA frequency sweep results was predicted by the Ellis model (see RBBird et al., "Dynamics of Polymer Liquids. Volume 1: Fluid Mechanics," Wiley-Interscience Publications (1987), p. 228) or the Carreau-Yasuda model (see K. Yasuda (1979) PhD Thesis, IT Cambridge).

[0281] Shear viscosity index SHI (0.5,50) The shear viscosity reduction index (SHI) was calculated as the ratio of the complex viscosity estimated at a shear stress of 0.5 kPa to the complex viscosity estimated at a shear stress of 50 kPa. (0.5,50) This provides information on the shear viscosity reduction behavior of polymer molten materials. High values ​​indicate a strong dependence of viscosity on changes in deformation rate (shear or frequency).

[0282] In this disclosure, the LCBF (Long Chain Branching Factor) was determined using η0 obtained by DMA (see U.S. Patent No. 10,442,921).

[0283] <Capillary Rheology> Viscosity profiles of different resins at different shear rates were obtained using rheological data obtained from a Dynisco LCR7000 capillary rheometer. In a capillary extrusion rheometer, the material is held in a temperature-controlled barrel and pushed into a precisely sized die by a piston. The apparent shear rate applied to the material is determined by the bore size, die size, and piston speed, and the apparent shear stress is calculated using the force and die size. Shear viscosity can be obtained from the capillary flow method using Poiseuille's law.

number

[0284] The shear rate, shear stress, and shear viscosity determined using Poiseuille's equation are usually referred to as apparent shear viscosity, apparent shear stress, and apparent shear rate. This is because the non-Newtonian properties of most fluids and the pressure drop across the die inlet and outlet pressures are not taken into account. The test temperature was set to 200°C. In this evaluation, the capillary length used was 30.48 mm and the die diameter was 1.524 mm.

[0285] <Melting Strength> Melt strength is measured at 190°C using a Rosand RH-7 capillary rheometer (barrel diameter = 15 mm) with a 2 mm diameter flat die and an L / D ratio of 10:1. Pressure transducer: 10,000 psi (68.95 MPa). Piston speed: 5.33 mm / min. Conveying angle: 52°. Incremental conveying rate: 50-80 m / min 2 or 65±15m / min 2 The molten polymer is extruded through a capillary die at a constant rate, and the polymer strand is then drawn out at an increasing transport rate until it bursts. The maximum steady-state value of the force in the plateau region of the force-time curve is defined as the melt strength of the polymer.

[0286] <Vicat softening point (temperature)> The Vicat softening point of the polymer sample was determined according to ASTM D1525-07 (published December 2009). This test determines the temperature at which a specified needle penetrates the sample when it is subjected to the test conditions of ASTM D1525-07, namely heating rate B (120 ± 10 °C / hr and a 938 gram load (10 ± 0.2 N load)).

[0287] <CYTSAF / TREF(CTREF)> The "composition distribution index" (hereinafter referred to as CDBI) of polyethylene compositions was measured using a CRYSTAF / TREF200+ unit equipped with an IR detector (hereinafter referred to as CTREF). The acronym "TREF" stands for Temperature Rising Elution Fractionation. CTREF was provided by Polymer Characterization SA (Valencia Technology Park, Gustave Eiffel, 8, Paterna, E-46980 Valencia, Spain). CTREF was operated in TREF mode, which measures the elution temperature, Co / Ho ratio (copolymer / homopolymer ratio), and CDBI (composition distribution index), i.e., CDBI 50 and CDBI 25 The chemical composition of the polymer sample was generated as a function of . A polymer sample (80-100 mg) was placed in a CTREF reaction vessel. 35 ml of 1,2,4-trichlorobenzene (TCB) was packed into the reaction vessel, and the polymer was dissolved by heating the solution at 150°C for 2 hours. An aliquot (1.5 mL) of the solution was then loaded into a CTREF column packed with stainless steel beads. The column loaded with the sample was stabilized at 110°C for 45 minutes. The polymer was then crystallized from the solution in the column by lowering the temperature to 30°C at a cooling rate of 0.09°C / min. The column was then equilibrated at 30°C for 30 minutes. Next, the crystallized polymer was eluted from the column by flowing TCB through the column at a rate of 0.75 mL / min, and the column was slowly heated from 30°C to 120°C at a heating rate of 0.25°C / min. Raw CTREF data was processed using Polymer CHAR software, Excel spreadsheets, and in-house developed CTREF software. CDBI 50 CDBI is defined as the percentage of polymer whose composition is within 50% of the median of the central comonomer composition. 50 This was calculated from the normalized cumulative integral of the compositional distribution curing and compositional distribution curve, as described in U.S. Patent No. 5,376,439. Those skilled in the art will understand that a calibration curve is necessary to convert the CTREF elution temperature to the comonomer content, i.e., the amount of comonomer in the ethylene / α-olefin polymer fraction that elutes at a specific temperature. The preparation of such a calibration curve is described in the prior art, e.g., Wild et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20(3), pp. 441-455, which is fully incorporated herein by reference. CDBI calculated in a similar manner 25 ;CDBI 25 This is defined as the percentage of polymer whose composition is 25% of the median of the central comonomer composition. At the end of each sample run, the CTREF column was washed for 30 minutes, specifically by heating the CTREF column to 160°C and flowing TCB through the column for 30 minutes (0.5 mL / min).

[0288] The above CTREF procedure is well known to those skilled in the art and can be used to determine: the modality of the TREF profile, CDBI 50 CDBI 25 The amount (by weight) of the substance in the polyethylene composition that elutes at temperatures above 90°C (i.e., the relative area of ​​the eluted fraction in the TREF profile at temperatures above 90°C), the amount (by weight) of the substance in the polyethylene composition that elutes at temperatures between 90°C and 98°C (i.e., the relative area of ​​the eluted fraction in the TREF profile at temperatures between 90°C and 98°C), and the temperature or temperature range in which the maximum elution intensity (elution peak) occurs.

[0289] <Long-chain branching coefficient (LCBF)> LCBF (dimensionless) was determined for polyethylene compositions using the method described in U.S. Patent No. 10,442,921, which is incorporated herein by reference.

[0290] The calculation of the long-chain branching coefficient (LCBF) involves multi-dispersion-corrected zero shear viscosity (ZSV), as detailed in the following paragraphs. c ) and short-chain branched (SCB) corrected intrinsic viscosity (IV c ) is necessary.

[0291] Zero shear viscosity (ZSV) with dimensions of Poise c The correction for ) was made as shown in equation (1):

number

[0292] Intrinsic viscosity (IV) with dimensions of dL / g c The correction for ) was made as shown in equation (2):

number

[0293] A "linear" ethylene copolymer (or linear ethylene homopolymer) that does not contain LCB or contains LCB at undetectable levels lies on the baseline defined by formula (3).

number

[0294] The LCBF is calculated by the following formula, which defines the horizontal shift (S) from the linear baseline. h ) and vertical shift (S v ) was done based on:

number

number

[0295] In equations (4) and (5), ZSV c and IV c However, each must have dimensions of poise and dL / g. Horizontal shift (S h ) is the intrinsic viscosity (IV c ZSV when ) is constant c It is a shift of , and if we remove the log function, its physical meaning becomes clear. That is, it is the ratio of two zero shear viscosities, and the same IV c ZSV of linear ethylene copolymer (or linear ethylene homopolymer) having c ZSV of the test sample c This is the horizontal shift (S h ) was dimensionless. Vertical shift (S v ) is zero shear viscosity (ZSV). c IV when ) is constant c It is a shift, and if we remove the log function, its physical meaning becomes clear. That is, it is the ratio of the two intrinsic viscosities, and the IV of the test sample. c For the same ZSV c IV of a linear ethylene copolymer (or linear ethylene homopolymer) having c This is the vertical shift (S v ) was dimensionless.

[0296] The dimensionless long-chain branching coefficient (LCBF) was defined by equation (6):

number

[0297] In one embodiment of the present disclosure, an ethylene polymer having LCB (e.g., a polyethylene composition) is characterized by having an LCBF (dimensionless) of 0.0010 or greater; in contrast, an ethylene polymer without LCB (or in which LCB cannot be detected) is characterized by having an LCBF (dimensionless) of less than 0.0010.

[0298] <Hexane extract> Hexane extracts were determined in accordance with Federal Regulation 21 CFR §177.1520 Para(c) 3.1 and 3.2. The amount of hexane-extractable substances in the sample was determined by gravimetric analysis.

[0299] <Film Optics> The optical properties of the film were measured as follows: haze and transparency, ASTM D1003-13 (November 15, 2013).

[0300] <Film Elmendorf tear resistance> The tear performance of the film (tear performance of the base unstretched multilayer precursor film and the stretched multilayer film) was determined according to ASTM D1922-09 (May 1, 2009); the term equivalent to tear is "Elmendorf tear." The tear performance of the film was measured in both the mechanical direction (MD) and the transverse direction (TD) of the inflation film.

[0301] <Water vapor transmission rate (WVTR)> Water vapor transmission rate (WVTR), the amount of water vapor that permeates per 100 square inches of film per day at a given film thickness (mill), or g / 100in. 2 The value (expressed as / day) was measured according to ASTM F1249-90 using an instrument sold under the name Ametek by MOCON (Minneapolis, USA). This test was conducted under conditions of 100°F (37.8°C) and 100% relative humidity.

[0302] <Oxygen transmission rate (OTR)> Oxygen permeability (OTR), 100 inches per day 2 per cm 2 The values ​​(represented by ) were measured according to ASTM D3985-17 using an instrument sold by MOCON (Minneapolis, USA) under the name Ametek. The tests were conducted under conditions of 23°C, 0% relative humidity, and 1 atm. A mixture of 98% nitrogen (N2) and 2% hydrogen (H2) was used as the carrier gas, and 100% oxygen (O2) was used as the test gas. The test was terminated when the change in oxygen flux fell to less than 1% during a 15-minute test cycle. The reported data are normalized (multiplied) by the film thickness and represent the average of four tests.

[0303] <Coefficient of friction (COF)> The coefficient of friction (COF) was measured using ASTM D-1894. Both kinetic and static friction characteristics are reported.

[0304] <Mechanical properties of film> Tensile tests in both the mechanical and transverse directions (MD and TD, respectively) were performed according to ASTM D882 (ASTM D882-10 and ASTM D882-12). The width of the specimen used for tensile property measurements was 1.0 inch. The elongation rate was 1 mm / min up to 5% strain, and then increased to 100 mm / min until fracture. The grip spacing was 100 mm. The measured mechanical properties were tensile fracture stress (reported in MPa), yield strain (%), yield stress (MPa), fracture strain (%), fracture stress (MPa), and E modulus (MPa).

[0305] <Film heat shrinkage rate (%)> The shrinkage rate of the film was measured using a 10 × 10 cm film test piece placed in an oven in air at 120°C for 5 minutes. The length of the heated film in the mechanical and transverse directions was compared to the original film, and the relative decrease was reported as the shrinkage rate. (%) Contraction rate = L initial -L final ) / L initial (In the formula, L initial and L final (These are the length before heat treatment and the length after heat treatment.)

[0306] <Film thickness> The film thickness of the stretched multilayer film was measured according to ASTM D6988-13.

[0307] <Preparation of polyethylene composition> The polyethylene composition was prepared using a mixed double catalyst system in an "in-series" double reactor solution polymerization process. The resulting polyethylene composition contained a first ethylene copolymer prepared with a single-site catalyst and a second ethylene copolymer prepared with a multi-site catalyst. A "in-series" double reactor, liquid-phase polymerization process, including one using a mixed double catalyst, is described in U.S. Patent Application Publication 2018 / 0305531. Essentially, in the "in-series" double reactor system, the outlet flow from the first polymerization reactor (R1) flows directly into the second polymerization reactor (R2). The pressure in R1 was approximately 14 MPa to 18 MPa, while R2 was operated at a lower pressure to facilitate continuous flow from R1 to R2. Both R1 and R2 were continuous stirred reactors (CSTRs) and stirred under conditions that ensured thorough mixing of the reactor contents. The process was operated continuously by supplying fresh process solvent, ethylene, 1-octene, and hydrogen to the reactors and removing the product. Note that in Examples 1 and 2, fresh 1-octene was supplied to both the first reactor (R1) and the second reactor (R2) (in fact, in Examples 1 and 2, more 1-octene was supplied to the second reactor than to the first). Methylpentane was used as the process solvent (a commercially available blend of methylpentane isomers). The volume of the first CSTR reactor (R1) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). The monomer (ethylene) and comonomer (1-octene) were purified using a conventional feed preparation system (such as contact with water, oxygen, and various absorption media to remove impurities such as polar contaminants) before being added to the reactors. The reactor feed was pumped into the reactors in the ratios shown in Table 1. The average residence time in a reactor is calculated by dividing the average flow rate by the volume of the reactor and is mainly influenced by the amount of solvent flowing through each reactor and the total amount of solvent flowing through the solution process.

[0308] In the first reactor (R1), the first ethylene copolymer was prepared using the following single-site catalyst components: diphenylmethylene (cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dimethyl [(2,7-tBu2Flu)Ph2C(Cp)HfMe2]; methylaluminoxane (MMAO-07); trityltetrakis(pentafluorophenyl)borate (tritylborate); and 2,6-di-tert-butyl-4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07) and 2,6-di-tert-butyl-4-ethylphenol were pre-mixed in-line and combined with diphenylmethylene (cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dimethyl and trityltetrakis(pentafluorophenyl)borate immediately before entering the polymerization reactor (R1). The efficiency of the single-site catalyst formulation was optimized by adjusting the molar ratio of the catalyst components and the R1 catalyst inlet temperature.

[0309] The second ethylene copolymer was prepared in a second reactor (R2) using the following Ziegler-Natta (Zn) catalyst components: butylethylmagnesium; tertiary butyl chloride; titanium tetrachloride; diethylaluminum ethoxide; and triethylaluminum. Using methylpentane as the catalyst solvent, an in-line Ziegler-Natta catalyst formulation was prepared using the following steps and then injected into the second reactor (R2). In step 1, a solution of triethylaluminum and butylethylmagnesium (Mg:Al=20, molars:molars) was mixed with a solution of tertiary butyl chloride and reacted for approximately 30 seconds to produce a MgCl2 support. In step 2, a solution of titanium tetrachloride was added to the mixture formed in step 1 and reacted for approximately 14 seconds before being injected into the second reactor (R2). The in-line Ziegler-Natta catalyst was activated in the reactor by injecting a solution of diethylaluminum ethoxide into R2. The amount of titanium tetrachloride added to the reactor is shown in Table 1. The efficiency of the in-line Ziegler-Natta catalyst formulation was optimized by adjusting the molar ratio of the catalyst components.

[0310] Polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the second reactor outlet flow. The catalyst deactivator used was octanoic acid (caprylic acid), commercially available from P&G Chemicals (Cincinnati, Ohio, USA). The catalyst deactivator was added so that the moles of the fatty acid added amounted to 50% of the total molar amount of hafnium, titanium, and aluminum added to the polymerization process; for clarity, the moles of added octanoic acid = 0.5 × (moles of hafnium + moles of titanium + moles of aluminum).

[0311] The ethylene interpolymer product was recovered from the process solvent using a two-stage defoliation process. Specifically, two vapor / liquid separators were used to pass the second bottom flow (from the second V / L separator) through a gear pump / pelletizer combination. DHT-4V (hydrotalcite), supplied by Kyowa Chemical Industry Co., Ltd. (Tokyo, Japan), was used as a passivator or acid scavenger in the continuous solution process. A slurry of DHT-4V in the process solvent was added before the first V / L separator.

[0312] Before pelletizing, the bimodal polyethylene composition was stabilized by adding approximately 500 ppm of IRGANOX® 1076 (primary antioxidant) and approximately 500 ppm of IRGAFOS® 168 (secondary antioxidant) based on the weight of the bimodal polyethylene composition. The antioxidants were dissolved in a process solvent and added between the first V / L separator and the second V / L separator.

[0313] Table 1 shows the reactor conditions (Examples 1 and 2) used to produce polyethylene compositions. Table 1 includes process parameters such as ethylene splits and 1-octene splits between reactors (R1 and R2), reactor temperature, and ethylene conversion rate. As can be seen from the data in Table 1, the so-called "octene splits" used to produce the polyethylene compositions contained fresh 1-octene supplied to both reactors, with more 1-octene supplied to the second reactor (R2). In Examples 1 and 2, the hydrogen level and temperature of the first reactor (R1) were optimized to produce a first ethylene copolymer with a weight-average molecular weight Mw greater than approximately 170,000 g / mol, while the hydrogen level and temperature of the second reactor (R2) were optimized to produce a second ethylene copolymer with a weight-average molecular weight Mw less than approximately 50,000 g / mol.

[0314] Table 2 shows the properties of polyethylene compositions produced according to Examples 1 and 2 of this disclosure.

[0315] For comparative purposes, polyethylene resins prepared by a solution polymerization process copolymerizing ethylene and 1-butene using a Ziegler-Natta catalyst, as described in Canadian Patent Application No. 3,102,574, both currently pending, are also included in Table 2 as Examples 3 and 4.

[0316] [Table 1]

[0317] [Table 2]

[0318] <Modeling of polyethylene compositions> Regarding the multi-component polyethylene composition, the M of the first and second ethylene copolymers w M n , and M w / M n This was calculated herein by reactor model simulation using input conditions adopted for actual pilot-scale polymerization operation (see results shown in Table 3) (see A. Hamielec, J. MacGregor, and A. Penlidis, "Copolymerization," Comprehensive Polymer Science and Supplements, Vol. 3, Chapter 2, p. 17, Elsevier, (1996) and JBP Soares and AE Hamielec, "Copolymerization of Olefins in a Series of Continuous Stirred-Tank Slurry-Reactors using Heterogeneous Ziegler-Natta and Metallocene Catalysts I. General Dynamic Mathematical Model," Polymer Reaction Engineering, 4(2&3), p. 153, (1996)).

[0319] This model takes as input several reactants (e.g., catalyst, monomers such as ethylene, comonomers such as 1-octene, hydrogen, solvent) flowing to each reactor, the temperature (in each reactor), and the monomer conversion rate (in each reactor), and calculates the polymer properties (of the polymers produced in each reactor, i.e., the first and second ethylene copolymers) using a terminal kinetic model of a series-connected continuous stirred tank reactor (CSTR). This "terminal kinetic model" assumes that the reaction rate depends on the monomer unit in the polymer chain where the active catalyst site is located (see A. Hamielec, J. MacGregor, and A. Penlidis, "Copolymerization," Comprehensive Polymer Science and Supplements, Vol. 3, Chapter 2, p. 17, Elsevier, (1996)). In this model, the statistics of monomer / comonomer unit insertions at the active catalyst center are valid, and to ensure that monomer / comonomers consumed through pathways other than propagation are negligible, the copolymer chain is assumed to have a moderately large molecular weight. This is known as the "long chain" approximation.

[0320] Terminal kinetic models of polymerization include rate equations for activation, initiation, propagation, chain transfer, and deactivation pathways. This model solves the steady-state conservation equations (e.g., total mass balance and heat balance) for the reactive fluid containing the reactants identified above.

[0321] The total mass balance of a typical continuous stirred tank reactor (CSTR) with a given number of inlets and outlets is given by the following equation:

number

[0322] Equation (1) can be further expanded to show the reactions for individual species.

number

[0323] The total heat balance can be solved for an adiabatic reactor and is given by the following equation:

number

[0324] The catalyst concentration supplied to each reactor is adjusted to match the experimentally determined ethylene conversion rate and reactor temperature values ​​in order to solve the equations of the reaction kinetics model (e.g., propagation rate, heat balance, mass balance).

[0325] The H2 concentration input to each reactor can be similarly adjusted so that the calculated molecular weight distribution of the polymers produced in both reactors (and therefore the molecular weight of the polymers produced in each reactor) matches that observed experimentally.

[0326] The weight fractions (wt1 and wt2) of the materials produced in each reactor (R1 and R2) are determined by knowing the mass flow rates of monomers and comonomers to each reactor and the conversion rates of monomers and comonomers in each reactor, which are calculated based on kinetic reactions.

[0327] Degree of polymerization (dp) of polymerization reaction n ) is given by the ratio of the rate of the chain propagation reaction to the rate of the chain transfer / termination reaction:

number

[0328] In the formula, k p11 [m1] is the propagation rate constant for monomer 1 to be added to the terminal growing polymer chain, and [m1] is the molar concentration of monomer 1 (ethylene) in the reactor, and k p12 k is the propagation rate constant for monomer 1 to add monomer 2 to the terminal growing polymer chain, and p21 [m2] is the propagation rate constant for monomer 2 to add monomer 1 to the terminal growing polymer chain, and [m2] is the molar concentration of monomer 2 (1-octene) in the reactor, and k p22 k is the propagation rate constant for monomer 2 to be added to the terminal growing polymer chain, and tm11 k is the stopping rate constant for chain transfer to monomer 1 in the terminal growth chain, and k tm12 k is the stopping rate constant for chain transfer from monomer 1 to monomer 2 in the terminal growth chain, and tm21 k is the stopping rate constant for chain transfer from monomer 2 to monomer 1 in the terminal growth chain, and tm22 k is the stopping rate constant for chain transfer to monomer 2 in the terminal growth chain, and k tS1 Herein, monomer 1 is the spontaneous chain termination rate constant of the terminal chain, and k tS2 Herein, monomer 2 is the spontaneous chain termination rate constant of the terminal chain, and k tH1 k is the rate constant for chain termination by hydrogen in the terminal chain of monomer 1, and tH2 φ1 is the rate constant for chain termination by hydrogen in the chain terminated by monomer 2. (φ1 and φ2 are the fractions of catalytic sites occupied by chains terminated by monomer 1 or monomer 2, respectively.)

[0329] Number average molecular weight of polymer (M n The molecular weight distribution of the polymer is determined from the degree of polymerization and the molecular weight of the monomer units. Assuming a Flory-Schultz distribution for a single-site catalyst, the molecular weight distribution of the polymer is determined using the following relationship, based on the number-average molecular weight of the polymer in a given reactor.

number

number

[0330] The Flory-Schultz distribution can be transformed into a general logarithmic GPC trace by applying the following:

number

[0331] Assuming the Flory-Schultz model, the different moments of molecular weight distribution can be calculated as follows:

number

number

number

[0332] Alternatively, when using a Ziegler-Natta catalyst, the molecular weight distribution of the polymer produced in a given reactor by the Ziegler-Natta catalyst can be modeled as described above, assuming that the sum of four such single-site catalytic sites is used, and each has a Flory-Schultz distribution. When considering the kinetics of the Ziegler-Natta catalyst process model, the total amount of Ziegler-Natta catalyst components supplied to the reactor is known, and it is assumed that each of the four modeled active catalytic sites has the same weight fraction, but each site has its own kinetics.

[0333] Finally, when long-chain branching occurs with a single-site catalyst, the molecular weight distribution of the polymer is determined using the following relationship (see JBP Soares, "Polyolefins with Long Chain Branches Made with Single-Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure," Macromolecular Materials and Engineering, Vol. 289, No. 1, pp. 70-87, Wiley-VCH, (2004), and JBP Soares and TFL McKenna, "Polyolefin Reaction Engineering," Wiley-VCH, (2012)).

number

number

number

number

[0334] The weight distribution can be converted to a general logarithmic scale GPC trace by applying the following:

number

[0335] From the weight distribution, moments with different molecular weight distributions can be calculated as follows:

number

number

number

[0336] <Branching frequency> The short-chain branching frequency (SCB2 / 1000 carbons) of the second ethylene copolymer is calculated using the following equation based on the kinetic equation and comonomer consumption:

number

number

[0337] The short-chain branching frequency of the first ethylene copolymer is estimated using the following formula:

number

[0338] <Melt Index (I2)> The melt index I2 is calculated based on the following formula:

number

[0339] <density> The density of the second ethylene copolymer prepared in R2 is calculated using the following formula, and the estimated SCB2, Mn, and M of the second ethylene copolymer are used. w Perform the calculation using the following as input:

number

[0340] The density of the first ethylene copolymer produced in R1 is estimated using the following formula:

number

[0341] [Table 3]

[0342] Figure 1 shows that the polyethylene compositions of this disclosure (Examples 1 and 2) have a bimodal GPC profile.

[0343] Figure 2 shows that the polyethylene compositions of this disclosure (Examples 1 and 2) have a bimodal GPC profile and have a relatively constant or slightly increasing comonomer content as the molecular weight increases (indicated by the short-chain branched content, SCB / 1000 skeletal carbon atoms).

[0344] Figure 3 shows that the polyethylene compositions of this disclosure (Examples 1 and 2) have more than 70% by weight of material that elutes at temperatures above 90°C, as determined by CTREF analysis. In fact, in Examples 1 and 2, the CTREF profiles show that a large elution fraction with one or two peaks dominates the elution profile, indicating that more than 50% by weight of polymer material elutes at temperatures between 90°C and 98°C. The different CTREF profiles observed for Examples 1 and 2 are consistent with the relatively flat (or uniform) comonomer distribution observed for these polyethylene compositions, as observed by GPC-FTIR analysis.

[0345] As shown in FIG. 4, the polyethylene compositions (Examples 1 and 2) made in accordance with the present disclosure have a melting point temperature of less than about 130° C. Without wishing to be bound by theory, the low melting point of the polymer may be useful during the biaxial stretching process for making the BOPE film structure; the low melting point indicates that there is more amorphous material present in the polyethylene composition, which may help to soften the sheet or film (made from the polymer composition) earlier during the stretching process (i.e., during MD and / or TD orientation), thereby improving the range of stretching process conditions.

[0346] FIG. 5 shows that the polyethylene compositions (Examples 1 and 2) made in accordance with the present disclosure have good apparent shear viscosity and good shear thinning behavior (e.g., the apparent shear viscosity decreases with an increase in shear rate or deformation rate). Without wishing to be bound by theory, the good shear thinning behavior allows for a high production rate to be obtained during the extrusion process for making the BOPE film in a tenter frame process.

[0347] <A. Preparation of the Unstretched Film (or "Base Structure")> The multilayer (3-layer) sheet is co-extruded through a 17.2-inch slot or flat die with a flexible lip (adjustable gap) using a combination of a biaxial screw extruder and a uniaxial screw extruder. The molten streams are combined near the entrance of the die. The multilayer web extruded from the die is secured to a casting roll or a cooling roll using an air knife and an edge pinner and is quenched on the cooling roll. The primary cooling roll temperature was set at 70° C. For convenience, this unstretched multilayer sheet may be referred to herein as the "base structure". The weight of the polymer used in each of the three layers is indicated in the form of A / B / C. For example, a base structure having two outer layers (or skin layers) each containing 18% by weight of the total polymer used in the film structure and a core layer containing 64% by weight of the total polymer used in the film structure is described as an 18 / 64 / 18 structure.

[0348] Using Examples 1 and 2, and Examples 3 and 4, a three-layer base film structure was prepared. That is, using the above procedure, the polyethylene compositions of Example 1, Example 2, Example 3, or Example 4 were used for each of the A layer, B layer, and C layer to produce an 18 / 64 / 18 film structure.

[0349] From each of these base multilayer film structures, a biaxially oriented polyethylene (BOPE) film was prepared using the procedure described in Part B below.

[0350] <B. Preparation of BOPE Film - Sequential Stretching> A BOPE film structure was produced using a sequential stretching process on a tenter frame biaxial stretching line. First, stretching / orientation in the machine direction was performed. Then, the "oriented" sheet was stretched in the transverse direction.

[0351] Machine direction orientation (MDO) was carried out using either a single-stage or multi-stage short-gap stretching process at a temperature of up to 265°F and a stretching ratio of up to about 6:1. Transverse direction orientation (TDO) was carried out in a plurality of zones (preheating zone, stretching zone, annealing zone, and finally one cooling zone). The temperature in the TDO stretching zone was up to 280°F and the stretching ratio was up to about 9:1.

[0352] MDO is achieved by preheating the base film and stretching the sheet between a set or stack of heating rollers rotating at different speeds. The difference in roll speeds determines the stretch ratio. Stretching can be performed on a single set of stretching rolls or on a series of stretching rolls. Stretching is generally performed at a temperature lower than the crystalline melting temperature (Tm) of the film. The MDO film is then fed into a tenter frame oven using clips on a chain mounted on rails and preheated. As the rails move away from each other, the edges of the film are pulled, stretching the film, resulting in lateral stretching. The width of the film is set by the distance between the rails and can be adjusted to achieve the desired stretch ratio. TDO is generally performed at a temperature equivalent to or slightly higher than that of MDO. The film can be annealed or relaxed as it exits the TDO unit. After TDO, the film can be cooled and wound. Table 3 outlines the common process conditions used in tenter frame processes.

[0353] [Table 4]

[0354] Table 4 shows the selected properties of the biaxially oriented multilayer film structures prepared from the polyethylene compositions of Examples 1 to 4. As shown in Table 4, biaxially oriented polyethylene (BOPE) film structures were prepared from the 18 / 64 / 18 basic structures of Examples 1 and 2, and Examples 3 and 4, at various MD and TD stretch ratios.

[0355] [Table 5]

[0356] As shown in the data in Table 4, each of the polyethylene compositions (Examples 1-4) was successfully stretched into a BOPE film structure using a sequential tenter-frame process. However, the polyethylene compositions of Examples 1 and 2, which had similar densities and melt index I2 to those of Examples 3 and 4, exhibited superior optical properties when converted into BOPE film structures. When the polyethylene composition of Example 2 was used to produce BOPE film structures, the haze values ​​were all less than approximately 10%, compared to all less than approximately 20% when using Example 1. In contrast, when the BOPE film structures were produced using Examples 3 and 4, the haze values ​​exceeded 60% and 30%, respectively. Examples 1 and 2 also showed superior transparency in the BOPE film structures compared to Examples 3 and 4. Considering the data shown in Table 4, those skilled in the art will see that polyethylene compositions prepared according to this disclosure are suitable for use in biaxial orientation, tenter-frame processes, at 0.940 g / cm³. 3 It will be recognized that additional and alternative polyethylene materials having the above density are provided. Polyethylene compositions prepared in accordance with this disclosure may be used in the manufacture of "all-polyethylene" BOPE films or film structures that have improved optical properties and are inherently highly recyclable.

[0357] Non-limiting embodiments of this disclosure include:

[0358] Embodiment A. A biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 A biaxially oriented polyethylene film structure having a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0359] Embodiment B. The biaxially oriented polyethylene film structure according to Embodiment A, wherein the polyethylene composition comprises copolymerized ethylene and 1-octene.

[0360] Embodiment C. A biaxially oriented polyethylene film structure according to Embodiment A or B, wherein the polyethylene composition has a molecular weight distribution Mw / Mn of 3.5 to 6.5.

[0361] Embodiment D. A biaxially oriented polyethylene film structure according to Embodiment A, B, or C, wherein the polyethylene composition has a Z-average molecular weight Mz of 250,000 g / mol or more.

[0362] Embodiment E. The polyethylene composition has a comonomer distribution index CDBI of more than 50% by weight. 50 A biaxially oriented polyethylene film structure according to Embodiment A, B, C, or D, having the following characteristics.

[0363] Embodiment F. The polyethylene composition has a comonomer distribution index CDBI of more than 65% by weight. 50 A biaxially oriented polyethylene film structure according to Embodiment A, B, C, or D, having the above characteristics.

[0364] Embodiment G. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, or F, wherein the polyethylene composition has a long-chain branching coefficient LCBF greater than 0.0010.

[0365] Embodiment H. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, or F, wherein the polyethylene composition has a long-chain branching coefficient LCBF greater than 0.0050.

[0366] Embodiment I. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, or F, wherein the polyethylene composition has a long-chain branching coefficient LCBF greater than 0.0100.

[0367] Embodiment J. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, or I, wherein the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 2.5 or more.

[0368] Embodiment K. The polyethylene composition has a melt flow ratio of 35 or more. 21 A biaxially oriented polyethylene film structure according to Embodiment A, B, C, D, E, F, G, H, I, or J, having / I2.

[0369] Embodiment L. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, or K, wherein the polyethylene composition contains more than 50% by weight of material that elutes at a temperature of 90°C to 98°C in temperature rise elution fractionation (CTREF) analysis.

[0370] Embodiment M. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, or L, wherein the polyethylene composition contains more than 70% by weight of material that elutes at temperatures above 90°C in temperature rise elution fractionation (CTREF) analysis.

[0371] Embodiment N. The polyethylene composition is 0.942 g / cm³ 3 ~0.954 g / cm³ 3 A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, or M, having a density of the above.

[0372] Embodiment O. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or N, wherein the polyethylene composition has a melt index I2 of 0.5 to 2.5 g / 10 min.

[0373] Embodiment P. A polyethylene composition with a melt flow ratio of 45 or higher 21 A biaxially oriented polyethylene film structure according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, or O, having / I2.

[0374] Embodiment Q. A polyethylene composition having a melt flow ratio of 35 to 100 I 21 A biaxially oriented polyethylene film structure according to Embodiment A, B, C, D, E, F, G, H, I, J, K, L, M, N, or O, having / I2.

[0375] Embodiment R. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, or Q, wherein the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 2.5 to 4.5.

[0376] Embodiment S. The polyethylene composition according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, or R, wherein the polyethylene composition has a Z average molecular weight distribution Mz / Mw greater than 2.8.

[0377] Embodiment T. A biaxially oriented polyethylene film structure according to Embodiments 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 of 250,000 to 500,000 g / mol.

[0378] Embodiment U. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, or T, wherein the ratio (SCB1 / SCB2) of the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer is 0.8 to 3.0.

[0379] Embodiment V. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, or T, wherein the ratio (SCB1 / SCB2) of the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer is 1.0 to 3.0.

[0380] Embodiment W. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, or V, wherein the second ethylene copolymer has a higher density than the first ethylene copolymer.

[0381] Embodiment X. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, or W, wherein the first ethylene copolymer has a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol.

[0382] Embodiment Y. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, or X, wherein the first ethylene copolymer has a melt index I2 of less than 0.5 g / 10 min.

[0383] Embodiment Z. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, or Y, wherein the second ethylene copolymer has a melt index I2 greater than 10.0 g / 10 min.

[0384] Embodiment AA. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, or Z, wherein the first ethylene copolymer has less than 7.5 short-chain branchings (SCB1 / 1000C) per 1000 carbon atoms.

[0385] Embodiment BB. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, or AA, wherein the second ethylene copolymer has less than 3.0 short-chain branchings per 1000 carbon atoms (SCB2 / 1000C).

[0386] Embodiment CC. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, or BB, wherein the first ethylene copolymer has a molecular weight distribution Mw / Mn of 1.7 to 2.3.

[0387] Embodiment DD. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, or CC, wherein the second ethylene copolymer has a molecular weight distribution Mw / Mn of 2.3 or more.

[0388] Embodiment EE. The first ethylene copolymer is 0.930 to 0.955 g / cm³. 3 A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, CC, or DD, having a density of the above.

[0389] Embodiment FF. The second ethylene copolymer is 0.935~0.960 g / cm³ 3 A biaxially oriented polyethylene film structure having the density of the following, according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, CC, DD, or EE.

[0390] Embodiment GG. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, A) A polyethylene composition comprising at least 75% by weight, B) A polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in an amount of 25% by weight or less. Includes, Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 A biaxially oriented polyethylene film structure having a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0391] Embodiment HH. Three adjacent layers each, A) A polyethylene composition containing at least 95% by weight, B) A polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in an amount of 5% by weight or less. A biaxially oriented polyethylene film structure according to embodiment GG, including the above.

[0392] Embodiment II. A biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 A biaxially oriented polyethylene film structure having a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0393] Embodiment JJ. The biaxially oriented polyethylene film structure according to Embodiment II, wherein the core layer constitutes at least 60% by weight of the total weight of the biaxially oriented film structure.

[0394] Embodiment KK. A process for preparing a biaxially oriented polyethylene film structure, The process is (a) A step of co-extruding a polyethylene composition into a base film structure having at least three adjacent layers, (b) A step of stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 10:1, (c) A step of stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1. Includes, (a) and (b) may be carried out in any order or simultaneously. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 The process has a density of 0.5-5.0 g / 10 min and a melt index of I2.

[0395] Embodiment LL. A process for preparing a biaxially oriented polyethylene film structure, The process is (a) A step of co-extruding a polymer blend containing at least 75% by weight of a polyethylene composition onto a base film structure containing at least three adjacent layers, (b) A step of stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 10:1, (c) A step of stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:1. Includes, (b) and (c) may be carried out in any order or simultaneously. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min and a melt index of I2. The remaining weight of the polymer blend is a polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in the process.

[0396] Embodiment MM. A biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. The polyethylene composition comprises polymerized ethylene and an alpha-olefin selected from the group consisting of 1-butene, 1-hexene, and 1-octene. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of Mw / Mn of 3.0-8.0. The biaxially oriented polyethylene film structure is a biaxially oriented polyethylene film structure having a haze value of less than 20%.

[0397] Embodiment NN. A biaxially oriented polyethylene film structure according to Embodiment MM, wherein the polyethylene composition comprises polymerized ethylene and 1-octene.

[0398] Embodiment OO. A biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. The polyethylene composition comprises polymerized ethylene and an alpha-olefin selected from the group consisting of 1-butene, 1-hexene, and 1-octene. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 It has a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of Mw / Mn of 3.0-8.0. The biaxially oriented polyethylene film structure has a haze value of less than 20%. Biaxially oriented polyethylene film structure.

[0399] Embodiment PP. A biaxially oriented polyethylene film structure according to Embodiment OO, wherein the polyethylene composition comprises polymerized ethylene and 1-octene.

[0400] Embodiment QQ. A biaxially oriented polyethylene film structure according to Embodiment OO or PP, wherein the core layer constitutes at least 60% by weight of the total weight of the biaxially oriented film structure.

[0401] Embodiment RR. A biaxially oriented polyethylene film structure comprising at least three layers, At least one layer comprises a polyethylene composition, Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index ratio I2, melt flow ratio I 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0402] Embodiment SS. A biaxially oriented polyethylene film structure comprising at least three layers, Each layer contains a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0403] Embodiment TT. A biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C.

[0404] Embodiment UU. A biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. Polyethylene composition, (i) 15-50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol, (ii) 85-50% by weight of a second ethylene copolymer and Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is between 0.8 and 3.5. The polyethylene composition contains 0.941 to 0.962 g / cm³. 3 Density, melt index I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow ratio I2, melt flow index 21 / I2, Z-average molecular weight distribution Mz / Mw greater than 2.5, comonomer distribution width index CDBI greater than 50% by weight 50 , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature rise elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure containing more than 70% by weight of material that elutes at temperatures above 90°C. [Industrial applicability]

[0405] A biaxially oriented polyethylene (BOPE) film structure is provided, comprising at least three layers. At least one layer has a density of 0.941–0.962 g / cm³. 3 The film contains a polyethylene composition having a density of 0.5-5.0 g / 10 min, a melt index of I2, and a molecular weight distribution of 3.0-8.0 Mw / Mn. BOPE film is suitable for a wide variety of packaging applications and has the potential to design highly recyclable "all-polyethylene" packages.

Claims

1. A biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. Polyethylene composition, (i) 15 to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 150,000 g / mol to 500,000 g / mol, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ A biaxially oriented polyethylene film structure having the following characteristics.

2. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition comprises ethylene and 1-octene.

3. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a molecular weight distribution Mw / Mn of 3.5 to 6.

5.

4. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a Z-average molecular weight Mz of 250,000 g / mol or more.

5. Polyethylene composition with a comonomer distribution index (CDBI) exceeding 50% by weight ５０ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

6. Polyethylene composition with a comonomer distribution index (CDBI) exceeding 65% by weight ５０ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

7. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a long-chain branching coefficient (LCBF) greater than 0.0010.

8. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a long-chain branching coefficient LCBF greater than 0.0050.

9. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a long-chain branching coefficient LCBF greater than 0.0100.

10. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 2.5 or more.

11. A polyethylene composition with a melt flow ratio of 35 or higher ２１ / I ２ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

12. The biaxially oriented polyethylene film structure according to claim 1, wherein, in temperature rise elution fractionation (CTREF) analysis, the polyethylene composition contains more than 50% by weight of a material that elutes at a temperature of 90°C to 98°C.

13. The biaxially oriented polyethylene film structure according to claim 1, wherein, in temperature rise elution fractionation (CTREF) analysis, the polyethylene composition contains more than 70% by weight of a material that elutes at temperatures above 90°C.

14. The polyethylene composition is 0.942 g / cm³ ３ ~0.954g / cm ３ A biaxially oriented polyethylene film structure according to claim 1, having the density of [a specific density].

15. The polyethylene composition has a melt index I of 0.5 to 2.5 g / 10 min ２ The biaxially oriented polyethylene film structure according to claim 1, which has the above properties

16. A polyethylene composition with a melt flow ratio of 45 or higher ２１ / I ２ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

17. The polyethylene composition has a melt flow ratio of 35 to 100. ２１ / I ２ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

18. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a Z-average molecular weight distribution Mz / Mw of 2.5 to 4.

5.

19. The polyethylene composition according to claim 1, wherein the polyethylene composition has a Z-average molecular weight distribution Mz / Mw greater than 2.

8.

20. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene composition has a Z-average molecular weight of 250,000 to 500,000 g / mol.

21. The biaxially oriented polyethylene film structure according to claim 1, wherein the ratio (SCB1 / SCB2) of the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and is 3.

0.

22. The biaxially oriented polyethylene film structure according to claim 1, wherein the ratio (SCB1 / SCB2) of the number of short-chain branches per 1,000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1,000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and is 2.

8.

23. The biaxially oriented polyethylene film structure according to claim 1, wherein the second ethylene copolymer has a higher density than the first ethylene copolymer.

24. The biaxially oriented polyethylene film structure according to claim 1, wherein the first ethylene copolymer has a weight-average molecular weight Mw of 170,000 g / mol to 470,000 g / mol.

25. The first ethylene copolymer has a melt index of less than 0.5 g / 10 min. ２ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

26. The second ethylene copolymer has a melt index of 10.0 g / 10 mins. ２ A biaxially oriented polyethylene film structure according to claim 1, having the following characteristics.

27. The biaxially oriented polyethylene film structure according to claim 1, wherein the first ethylene copolymer has less than 7.5 short-chain branchings (SCB1 / 1000C) per 1000 carbon atoms.

28. The biaxially oriented polyethylene film structure according to claim 1, wherein the second ethylene copolymer has less than 3.0 short-chain branchings (SCB2 / 1000C) per 1000 carbon atoms.

29. The biaxially oriented polyethylene film structure according to claim 1, wherein the first ethylene copolymer has a molecular weight distribution Mw / Mn of 1.7 to 2.

3.

30. The biaxially oriented polyethylene film structure according to claim 1, wherein the second ethylene copolymer has a molecular weight distribution Mw / Mn of 2.3 or more.

31. The first ethylene copolymer is present in a concentration of 0.930–0.955 g / cm³. ３ A biaxially oriented polyethylene film structure according to claim 1, having the density of [a specific density].

32. The second ethylene copolymer is present in a concentration of 0.935–0.960 g / cm³. ３ A biaxially oriented polyethylene film structure according to claim 1, having the density of [a specific density].

33. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, A) A polyethylene composition comprising at least 75% by weight, B) A polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in an amount of 25% by weight or less. Includes, Polyethylene composition, (i) 15 to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 150,000 g / mol to 500,000 g / mol, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ A biaxially oriented polyethylene film structure having the following characteristics.

34. Each of the three adjacent layers, A) A polyethylene composition comprising at least 95% by weight, B) A polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in an amount of 5% by weight or less. A biaxially oriented polyethylene film structure according to claim 33, comprising:

35. A biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. Polyethylene composition, (i) 15 to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 150,000 g / mol to 500,000 g / mol, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ A biaxially oriented polyethylene film structure having the following characteristics.

36. The biaxially oriented polyethylene film structure according to claim 35, wherein the core layer constitutes at least 60% by weight of the total weight of the biaxially oriented film structure.

37. A process for preparing a biaxially oriented polyethylene film structure, The process is (a) A step of co-extruding a polyethylene composition into a base film structure having at least three adjacent layers, (b) A step of stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 10:1, (c) A step of stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:

1. Includes, (a) and (b) may be carried out in any order or simultaneously. Polyethylene composition, (i) 15 to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 150,000 g / mol to 500,000 g / mol, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ A process that has

38. A process for preparing a biaxially oriented polyethylene film structure, The process is (a) A step of co-extruding a polymer blend containing at least 75% by weight of a polyethylene composition onto a base film structure containing at least three adjacent layers, (b) A step of stretching the base film structure in the machine direction to a stretch ratio of 3:1 to 10:1, (c) A step of stretching the base film structure in the transverse direction to a stretch ratio of 3:1 to 12:

1. Includes, (b) and (c) may be carried out in any order or simultaneously. Polyethylene composition, (i) 15 to 50% by weight of a first ethylene copolymer having a weight-average molecular weight Mw of 150,000 g / mol to 500,000 g / mol, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ It has, The remaining weight of the polymer blend is a polymer selected from the group consisting of LLDPE, VLDPE, MDPE, HDPE and mixtures thereof, in the process.

39. A biaxially oriented polyethylene film structure comprising at least three layers, At least one layer comprises a polyethylene composition, Polyethylene composition, (i) 15 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, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ , melt flow ratio I of 35 or more ２１ / I ２ , Z-average molecular weight distribution Mz / Mw of 2.5 or higher, comonomer distribution width index CDBI exceeding 50% by weight ５０ , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature-dependent elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure having more than 70% by weight of material that elutes at temperatures above 90°C.

40. A biaxially oriented polyethylene film structure comprising at least three layers, Each layer contains a polyethylene composition. Polyethylene composition, (i) 15 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, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ , melt flow ratio I of 35 or more ２１ / I ２ , Z-average molecular weight distribution Mz / Mw of 2.5 or higher, comonomer distribution width index CDBI exceeding 50% by weight ５０ , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature-dependent elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure having more than 70% by weight of material that elutes at temperatures above 90°C.

41. A biaxially oriented polyethylene film structure comprising at least three layers, Each of the three adjacent layers contains a polyethylene composition. Polyethylene composition, (i) 15 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, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ , melt flow ratio I of 35 or more ２１ / I ２ , Z-average molecular weight distribution Mz / Mw of 2.5 or higher, comonomer distribution width index CDBI exceeding 50% by weight ５０ , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature-dependent elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure having more than 70% by weight of material that elutes at temperatures above 90°C.

42. A biaxially oriented polyethylene film structure, The core layer, The first skin layer adjacent to the first side of the core layer, The second skin layer adjacent to the second side of the core layer and Includes, Each of the core layer, the first skin layer, and the second skin layer comprises a polyethylene composition. Polyethylene composition, (i) 15 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, (ii) 85 to 50% by weight of a second ethylene copolymer having a weight-average molecular weight Mw of 5,000 g / mol to 75,000 g / mol Includes, The first ethylene copolymer has a higher weight-average molecular weight Mw than the second ethylene copolymer. The ratio (SCB1 / SCB2) of the number of short-chain branches per 1000 carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per 1000 carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 and between 1.0 and 3.

5. The polyethylene composition contains 0.941 to 0.962 g / cm³. ３ Density, 0.5-5.0 g / 10 min, Melt Index I ２ , melt flow ratio I of 35 or more ２１ / I ２ , Z-average molecular weight distribution Mz / Mw of 2.5 or higher, comonomer distribution width index CDBI exceeding 50% by weight ５０ , has a long-chain branching coefficient LCBF greater than 0.0010, In temperature-dependent elution fractionation (CTREF) analysis, the polyethylene composition is a biaxially oriented polyethylene film structure having more than 70% by weight of material that elutes at temperatures above 90°C.

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