Biaxially oriented film

Abstract

The biaxially oriented polyethylene film structure comprises at least three layers including a core layer, the core layer having a viscosity of i) 0.940 g / cm 3 and ii) 50 to 99.5 wt. % of a first polyethylene which is an ethylene copolymer having a density of at least 0.950 g / cm 3 and 0.5 to 50 weight percent of a second polyethylene, the polyethylene homopolymer composition further comprising a nucleating agent or mixture of nucleating agents. The biaxially oriented film has excellent optical properties.

Description

[Technical Field]

[0001] This disclosure relates to a BOPE film or film structure comprising at least three layers and having good optical properties. [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 bending crack resistance, as well as improved optical properties (for example, reduced haze and increased transparency).

[0004] BOPE film has the potential to be suitable for a wide variety of packaging applications, and the improved properties observed in biaxially oriented films or film structures may enable the design of "all-polyethylene" packaging (as opposed to packaging made with different types of polymers). Such "all-polyethylene" packaging would 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 (e.g., approximately 0.950 g / cm³) was used. 3 High-density polyethylene (high-density polyethylene) having a density exceeding a certain level has been observed to behave poorly when subjected to biaxial orientation. In fact, producing BOPE films from high-density polyethylene required specific or precise process conditions (i.e., a very narrow process window). Alternatively, high-density polyethylene has been co-extruded using an adhesion promoter layer ("casting promoter"), such as a layer containing low-density polyethylene material and its blends, or a layer containing ethylene / propylene copolymer and terpolymer, as an adjacent co-extruded layer. Alternatively, high-density polyethylene has been co-extruded using an adhesion promoter layer ("casting promoter"), for example, a layer containing low-density polyethylene material and its blends, or ethylene / propylene copolymer and terpolymer, as an adjacent co-extruded layer.

[0006] There is still a need for new polyethylene compositions, particularly high-density polyethylene compositions that offer improved "stretchability" in BOPE processes, such as the Tenterframe BOPE process. [Overview of the Initiative]

[0007] One embodiment of the present disclosure provides an "all-polyethylene" biaxially oriented film structure that has good optical properties and can be improved in recyclability compared to BOPE films made from mixed polymer materials.

[0008] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0009] 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, Including a second skin layer adjacent to the second side of the core layer, The core layer, the first skin layer, and the second skin layer are each: i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0010] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of a second polyethylene, the second polyethylene being a high-density polyethylene having a density of at least 0.950 g / cm 3 and comprising a second polyethylene, the high-density polyethylene comprising a nucleating agent or a mixture of nucleating agents, The biaxially oriented polyethylene film structure is a biaxially oriented polyethylene film structure having a haze value of less than 15%.

[0011] <00002***>One embodiment of the present disclosure is a biaxially oriented polyethylene 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, each of the core layer, the first skin layer, and the second skin layer comprising i) 50 to 99.5% by weight of a first polyethylene, the first polyethylene being an ethylene copolymer having a density greater than 0.940 g / cm 3 and a first polyethylene, ii) 0.5 to 50% by weight of a second polyethylene, the second polyethylene being a high-density polyethylene having a density of at least 0.950 g / cm 3 and a second polyethylene, the high-density polyethylene comprising a nucleating agent or a mixture of nucleating agents, The biaxially oriented polyethylene film structure is a biaxially oriented polyethylene film structure having a haze value of less than 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [Figure 1]A schematic diagram of a multizone reactor system is shown, including a first polymerization zone defined by a first tubular reactor, a second polymerization zone defined by a tank reactor, and a third polymerization zone defined by a second tubular reactor. The schematic diagram is representative of a multizone reactor system and is not drawn to scale. The approximate locations of hydrogenation into the multizone reactor system are also indicated (locations A and B). [Modes for carrying out the invention]

[0013] 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.

[0014] 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.

[0015] 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. 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.

[0016] The term "heterogeneously branched polyethylene" refers to a subset of polymers in the ethylene polymer group produced using heterogeneous catalytic systems, non-limiting examples of which include Ziegler-Natta catalysts or chromium catalysts, both of which are well known in the art.

[0017] The term "uniformly branched polyethylene" refers to a subset of polymers in the ethylene polymer group produced using single-site catalysts, including non-limiting examples such as metallocene catalysts, phosphine imine catalysts, and constrained geometry catalysts, all of which are well known in the art.

[0018] Typically, uniformly branched polyethylene has a narrow molecular weight distribution, for example, in gel permeation chromatography (GPC) w / M nThe value is less than approximately 2.8, especially less than approximately 2.3, but exceptions may occur, M w and M n These refer to the average molecular weight and number, respectively. In contrast, the M of heterogeneously branched ethylene polymers w / M n Typically, it is a uniform polyethylene M w / M n It is larger than [this value]. Generally, uniformly branched ethylene polymers also have a narrow comonomer distribution, meaning that each polymer within the molecular weight distribution has a similar comonomer content. Often, the Composition Distribution Width Index (CDBI) is used to quantify how comonomers are distributed within an ethylene polymer and to distinguish ethylene polymers produced by different catalysts or processes. 50 "CBDBI of ethylene copolymers" is defined as the percentage of ethylene polymer whose composition is within 50% by weight (wt%) of the median comonomer composition, and this definition is consistent with the definition contained in International Publication No. 93 / 03093, assigned to Exxon Chemical Patents Inc. 50 CDBI can be calculated from the TREF curve (Temperature Rising Elution Fractionation), and the TREF method is described in Wild et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20(3), pp. 441-455. Typically, CDBI of a uniformly branched ethylene polymer is used. 50 The percentage is over 70% or over 75%. In contrast, the CDBI of heterogeneously branched ethylene polymers containing α-olefins is... 50 Generally, CDBI is a homogeneous ethylene polymer. 50 It is lower than that. For example, the CDBI of a non-uniformly branched ethylene polymer. 50 It may be less than approximately 75%, or less than approximately 70%.

[0019] As is well known to those skilled in the art, uniformly branched ethylene polymers are often further subdivided into “linear homogeneous ethylene polymers” and “substantially linear homogeneous ethylene polymers.” These two subgroups differ in the amount of long-chain branching. More specifically, linear homogeneous ethylene polymers have less than about 0.01 long-chain branches per 1000 carbon atoms, while substantially linear ethylene polymers have about 0.01 to more than about 3.0 long-chain branches per 1000 carbon atoms. Long-chain branches are essentially polymers, i.e., their length is similar to the polymer to which they are bonded. Hereinafter, in this disclosure, the terms “uniformly branched polyethylene” or “uniformly branched ethylene polymer” refer to both linear homogeneous ethylene polymers and substantially linear homogeneous ethylene polymers.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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 to mean that the film can have a plurality of layers (film structures that can have at least two layers, at least three layers, at least four layers, at least five layers, etc.).

[0024] In the present 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 percentage than other non-polyethylene polymers based on the total weight of the polymers present in the film or film structure).

[0025] The phrase "all polyethylene" as used herein, 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 the polymers present in the film or film structure).

[0026] The "skin" layer is the outer layer of a multilayer film structure (i.e., the layer having an outer surface exposed to the environment).

[0027] The "core" layer is the inner layer of a multilayer film structure (i.e., the layer adjacent to the inner surface of the skin layer, or another inner layer, or another core layer). A multilayer film structure can have one or more core layers that are considered adjacent inner layers.

[0028] <BOPE film structure> In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each including at least one core layer. At least one core layer, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 The present invention comprises a second polyethylene, which is high-density polyethylene having a density such that the high-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0029] In one embodiment of the present disclosure, a biaxially oriented film or film structure comprises at least three adjacent layers, each including at least one core layer. At least one core layer, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents.

[0030] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 It comprises a second polyethylene, which is a high-density polyethylene having a density of , High-density polyethylene is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0031] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure comprises at least three layers. The three adjacent layers are, i) 70-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 30% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 It comprises a second polyethylene, which is a high-density polyethylene having a density of , High-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0032] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure comprises at least three layers. The three adjacent layers are, i) 90-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 10% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 It comprises a second polyethylene, which is a high-density polyethylene having a density of , High-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0033] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0034] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure comprises at least three layers. The three adjacent layers are, i) 70-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 30% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents.

[0035] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure comprises at least three layers. The three adjacent layers are, i) 90-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 10% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents.

[0036] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three adjacent layers, Each layer, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 It comprises a second polyethylene, which is a high-density polyethylene having a density of , High-density polyethylene is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0037] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure includes at least three adjacent layers, Each layer, i) 70-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 30% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 It comprises a second polyethylene, which is a high-density polyethylene having a density of , High-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0038] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure includes at least three adjacent layers, Each layer, i) 90-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 10% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 It comprises a second polyethylene, which is a high-density polyethylene having a density of , High-density polyethylene is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0039] One embodiment of the present disclosure is a biaxially oriented polyethylene film structure comprising at least three adjacent layers, Each layer, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition is a biaxially oriented polyethylene film structure containing a nucleating agent or a mixture of nucleating agents.

[0040] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure includes at least three adjacent layers, Each layer, i) 70-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 30% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents.

[0041] In one embodiment of the present disclosure, the biaxially oriented polyethylene film structure includes at least three adjacent layers, Each layer, i) 90-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 10% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising The polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents.

[0042] In one embodiment of the present disclosure, the nucleating agent or mixture of nucleating agents present in the high-density polyethylene is present in an amount that provides 1 to 1000 ppm (parts per million) of the nucleating agent or mixture of nucleating agents based on the total weight of the polymer material used in the film layer (i.e., based on the total weight of i) first polyethylene and ii) high-density polyethylene used in the film layer).

[0043] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the high-density polyethylene is present in an amount that provides 5 to 1000 ppm (parts per million), or 5 to 750 ppm, or 5 to 500 ppm, or 5 to 400 ppm, or 5 to 350 ppm, or 5 to 250 ppm, or 5 to 150 ppm, or 5 to 100 ppm, based on the total weight of the polymer material used in the film layer (i.e., based on the total weight of i) first polyethylene and ii) high-density polyethylene used in the film layer).

[0044] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the high-density polyethylene is present in an amount that provides less than 500 ppm (parts per million), or less than 350 ppm, or less than 250 ppm, or less than 150 ppm, or less than 100 ppm, or less than 75 ppm, or less than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than 25 ppm, or less than 20 ppm, or less than 15 ppm, or less than 10 ppm, based on the total weight of the polymer material used in the film layer (i.e., based on the total weight of i) first polyethylene and ii) high-density polyethylene used in the film layer).

[0045] In one embodiment of the present disclosure, the nucleating agent or mixture of nucleating agents present in the polyethylene homopolymer composition is present in an amount that provides 1 to 1,000 ppm (parts per million) of the nucleating agent or mixture of nucleating agents based on the total weight of the polymer material used in the film layer (i.e., based on the total weight of i) the first polyethylene and ii) the polyethylene homopolymer composition used in the film layer).

[0046] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the polyethylene homopolymer composition is present in an amount that provides 5 to 1000 ppm (parts per million), or 5 to 750 ppm, or 5 to 500 ppm, or 5 to 400 ppm, or 5 to 350 ppm, or 5 to 250 ppm, or 5 to 150 ppm, or 5 to 100 ppm, based on the total weight of the polymer material used in the film layer (i.e., based on the total weight of i) the first polyethylene and ii) the polyethylene homopolymer composition used in the film layer).

[0047] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the polyethylene homopolymer composition is present in an amount that provides less than 500 ppm (parts per million), or less than 350 ppm, or less than 250 ppm, or less than 150 ppm, or less than 100 ppm, or less than 75 ppm, or less than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than 25 ppm, or less than 20 ppm, or less than 15 ppm, or less than 10 ppm, based on the total weight of the polymer material used in the film layer (i.e., based on the total weight of i) the first polyethylene and ii) the polyethylene homopolymer composition used in the film layer).

[0048] One embodiment of the present disclosure is a biaxially oriented polyethylene 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, wherein each of the core layer, the first skin layer, and the second skin layer is i) 50 to 99.5% by weight of a first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 ii) a first polyethylene which is an ethylene copolymer having a density exceeding , and ii) a second polyethylene in an amount of 0.5 to 50% by weight, wherein the second polyethylene has a density of at least 0.950 g / cm³ 3 A biaxially oriented polyethylene film structure comprising a second polyethylene having a density of , wherein the high-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0049] In one embodiment of the present disclosure, the core layer, the first skin layer, and the second skin layer are each i) 70-99.5% by weight of a first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 ii) a first polyethylene which is an ethylene copolymer having a density exceeding , and ii) a second polyethylene in an amount of 0.5 to 30% by weight, wherein the second polyethylene has a density of at least 0.950 g / cm³ 3The present invention comprises a second polyethylene, which is high-density polyethylene having a density such that the high-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0050] In one embodiment of the present disclosure, the core layer, the first skin layer, and the second skin layer are each i) 90-99.5% by weight of a first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 ii) a first polyethylene which is an ethylene copolymer having a density exceeding , and ii) a second polyethylene in an amount of 0.5 to 10% by weight, wherein the second polyethylene has a density of at least 0.950 g / cm³ 3 The present invention comprises a second polyethylene, which is high-density polyethylene having a density such that the high-density polyethylene contains a nucleating agent or a mixture of nucleating agents.

[0051] In one embodiment of the present disclosure, the nucleating agent or mixture of nucleating agents present in the high-density polyethylene is present in an amount that provides 1 to 1,000 ppm (parts per million) of the nucleating agent or mixture of nucleating agents based on the total weight of the polymer material used in each of the core layer, the first skin layer, and the second skin layer (i.e., based on the total weight of i) first polyethylene and ii) high-density polyethylene used in each of the core layer, the first skin layer, and the second skin layer).

[0052] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the high-density polyethylene is present in an amount that provides 5 to 1,000 ppm (parts per million), or 5 to 750 ppm, or 5 to 500 ppm, or 5 to 400 ppm, or 5 to 350 ppm, or 5 to 250 ppm, or 5 to 150 ppm, or 5 to 100 ppm, based on the total weight of the polymer material used in each of the core layer, the first skin layer, and the second skin layer (i.e., based on the total weight of i) first polyethylene and ii) high-density polyethylene used in each of the core layer, the first skin layer, and the second skin layer.

[0053] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the high-density polyethylene is present in an amount that provides less than 500 ppm (parts per million), or less than 350 ppm, or less than 250 ppm, or less than 150 ppm, or less than 100 ppm, or less than 75 ppm, or less than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than 25 ppm, or less than 20 ppm, or less than 15 ppm, or less than 10 ppm, based on the total weight of the polymer material used in each of the core layer, the first skin layer, and the second skin layer (i.e., based on the total weight of i) first polyethylene and ii) high-density polyethylene used in each of the core layer, the first skin layer, and the second skin layer.

[0054] One embodiment of the present disclosure is a biaxially oriented polyethylene 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, wherein each of the core layer, the first skin layer, and the second skin layer is i) 50 to 99.5% by weight of a first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 ii) a first polyethylene which is an ethylene copolymer having a density exceeding , and ii) a second polyethylene in an amount of 0.5 to 50% by weight, wherein the second polyethylene has a density of at least 0.950 g / cm³ 3 A biaxially oriented polyethylene film structure comprising a second polyethylene having a density of , wherein the polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents.

[0055] In one embodiment of the present disclosure, the core layer, the first skin layer, and the second skin layer are each i) 70-99.5% by weight of a first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 ii) a first polyethylene which is an ethylene copolymer having a density exceeding , and ii) a second polyethylene in an amount of 0.5 to 30% by weight, wherein the second polyethylene has a density of at least 0.950 g / cm³ 3A polyethylene homopolymer composition having a density of a second polyethylene, comprising a polyethylene homopolymer composition comprising a nucleating agent or a mixture of nucleating agents.

[0056] In one embodiment of the present disclosure, the core layer, the first skin layer, and the second skin layer are each i) 90-99.5% by weight of a first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 ii) a first polyethylene which is an ethylene copolymer having a density exceeding , and ii) a second polyethylene in an amount of 0.5 to 10% by weight, wherein the second polyethylene has a density of at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene, comprising a polyethylene homopolymer composition comprising a nucleating agent or a mixture of nucleating agents.

[0057] In one embodiment of the present disclosure, the nucleating agent or mixture of nucleating agents present in the polyethylene homopolymer composition is present in an amount that provides 1 to 1,000 ppm (parts per million) of the nucleating agent or mixture of nucleating agents based on the total weight of the polymer material used in each of the core layer, the first skin layer, and the second skin layer (i.e., based on the total weight of i) the first polyethylene and ii) the polyethylene homopolymer composition used in each of the core layer, the first skin layer, and the second skin layer).

[0058] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the polyethylene homopolymer composition is present in an amount that provides 5 to 1,000 ppm (parts per million), or 5 to 750 ppm, or 5 to 500 ppm, or 5 to 400 ppm, or 5 to 350 ppm, or 5 to 250 ppm, or 5 to 150 ppm, or 5 to 100 ppm, based on the total weight of polymer material used in each of the core layer, the first skin layer, and the second skin layer (i.e., based on the total weight of i) the first polyethylene and ii) the polyethylene homopolymer composition used in each of the core layer, the first skin layer, and the second skin layer.

[0059] In further embodiments of the present disclosure, the nucleating agent or mixture of nucleating agents present in the polyethylene homopolymer composition is present in an amount that provides less than 500 ppm (parts per million), or less than 350 ppm, or less than 250 ppm, or less than 150 ppm, or less than 100 ppm, or less than 75 ppm, or less than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than 25 ppm, or less than 20 ppm, or less than 15 ppm, or less than 10 ppm, based on the total weight of the polymer material used in each of the core layer, the first skin layer, and the second skin layer (i.e., based on the total weight of i) the first polyethylene and ii) the polyethylene homopolymer composition used in each of the core layer, the first skin layer, and the second skin layer.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] A biaxially oriented polyethylene (BOPE) film or film structure can be manufactured using a tenter frame process in one embodiment of the present disclosure.

[0066] 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 with 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.

[0067] 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.

[0068] 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 finally winding up the film structure.

[0069] 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. In one embodiment, during simultaneous stretching, the base film may be held by tenter clips (as described above) and suspended in the air while being stretched in both the MD and TD directions.

[0070] 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.

[0071] 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%.

[0072] In embodiments of the present disclosure, a biaxially oriented film or 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 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%.

[0073] In embodiments of the present disclosure, a biaxially oriented film or 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 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%.

[0074] Biaxially oriented films prepared according to this disclosure may be suitable for use in a wide variety of packaging applications. In one embodiment, the biaxially oriented film structure can be used in a laminate structure. For example, the biaxially oriented film structure of this disclosure can be used as a printed web when laminated to a sealant web, which may also be made from polyethylene but may contain a lower-density polyethylene material. 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.

[0075] Further embodiments of the first polyethylene used in biaxially oriented film structures are shown below.

[0076] Further embodiments of a second polyethylene used in biaxially oriented film structures are shown below.

[0077] <First Polyethylene> In one embodiment of the present disclosure, the first polyethylene is produced using a multi-site catalyst system, non-limiting examples of which include Ziegler-Natta polymerization catalysts and chromium catalysts, both of which are well known in the art.

[0078] In one embodiment of the present disclosure, the first polyethylene is produced using a Ziegler-Natta polymerization catalyst well known in the art.

[0079] In one embodiment of the present disclosure, the first polyethylene is produced using a Ziegler-Natta polymerization catalyst in a solution-phase polymerization process.

[0080] In one embodiment of the present disclosure, the first polyethylene is produced using a Ziegler-Natta polymerization catalyst in a solution-phase polymerization process carried out in a multizone polymerization reactor system.

[0081] In one embodiment of the present disclosure, the first polyethylene is produced using a Ziegler-Natta polymerization catalyst in a solution-phase polymerization process carried out in a multizone polymerization reactor system, the multizone polymerization reactor system comprising first, second, and third polymerization zones.

[0082] In one embodiment of the present disclosure, the first polyethylene is an ethylene copolymer.

[0083] In embodiments of the present disclosure, the alpha-olefins that can copolymerize with ethylene to produce a first polyethylene may be selected from the group comprising 1-butene, 1-pentene, 1-hexene, and 1-octene, and mixtures thereof.

[0084] In one embodiment of the present disclosure, the first polyethylene comprises ethylene and at least one alpha-olefin having 4 to 8 carbon atoms.

[0085] In one embodiment of the present disclosure, the first polyethylene is an ethylene / 1-butene copolymer.

[0086] In embodiments of this disclosure, the first polyethylene is at least 0.940 g / cm³ 3 , or 0.940 g / cm³ 3 exceeding, or at least 0.941 g / cm³ 3 It has a density of .

[0087] In embodiments of this disclosure, the first polyethylene is 0.940 to 0.965 g / cm³. 3 , or 0.940~0.963 g / cm³ 3 , or 0.941~0.965 g / cm³ 3 , or 0.941~0.963 g / cm³ 3 , or 0.941~0.962g / 10 min, or 0.940~0.960g / cm³ 3 , or 0.940~0.958 g / cm³ 3 , or 0.940~0.956 g / cm³ 3 , or 0.940~0.952 g / cm³ 3, or 0.940~0.950 g / cm³ 3 , or 0.942~0.960 g / cm³ 3 , or 0.942~0.958 g / cm³ 3 , or 0.942~0.956 g / cm³ 3 , or 0.942~0.952 g / cm³ 3 , or 0.942~0.950 g / cm³ 3 It has a density of .

[0088] In embodiments of the present disclosure, the melt index I2 of the first polyethylene is at least 0.50 g / 10 min, or at least 0.75 g / 10 min, or at least 0.80 g / 10 min, or at least 1.0 g / 10 min.

[0089] In embodiments of this disclosure, the melt index I2 of the first polyethylene may be approximately 0.01 g / 10 min to approximately 10.0 g / 10 min, or approximately 0.1 g / 10 min to approximately 10.0 g / 10 min, or approximately 0.5 to approximately 10.0 g / 10 min, or approximately 0.1 g / 10 min to approximately 5.0 g / 10 min, or approximately 0.1 g / 10 min to approximately 3.0 g / 10 min, or approximately 0.5 g / 10 min to approximately 5.0 g / 10 min, or approximately 0.5 g / 10 min to approximately 3.0 g / min, or approximately 0.5 g / 10 min to approximately 2.5 g / 10 min.

[0090] In embodiments of this disclosure, the melt flow ratio (MFR) of the first polyethylene is 21 / I2 is greater than 50, or greater than 60, or greater than 65, or greater than 70, or greater than 75.

[0091] In one embodiment of the present disclosure, the melt flow ratio (MFR) of the first polyethylene is 21 / I2 is less than 115.

[0092] In embodiments of this disclosure, the melt flow ratio (MFR) of the first polyethylene is 21 / I2 is between 50 and 120, or 50 and 115, or greater than 65 but less than 115, or greater than 75 but less than 115.

[0093] In one embodiment of the present disclosure, the first polyethylene is approximately 5,000 to approximately 75,000, or approximately 5,000 to approximately 50,000, or approximately 5,000 to approximately 30,000, or approximately 5,000 to approximately 25,000, or approximately 7,500 to approximately 50,000, or approximately 7,500 to approximately 30,000, or approximately 7,500 to approximately 25,000, or approximately 5,000 to approximately 20,000, or approximately 5, Number average molecular weight M of 000 to approximately 15,000, or approximately 7,500 to approximately 20,000, or approximately 7,500 to approximately 15,000, or approximately 10,000 to approximately 15,000, or approximately 10,000 to approximately 12,500, or approximately 11,000 to approximately 15,000, or approximately 11,000 to approximately 12,500, or greater than 11,000 to less than 12,500, or greater than 11,000 to less than 15,000 n It has.

[0094] In one embodiment of the present disclosure, the first polyethylene has a weight-average molecular weight M of approximately 75,000 to approximately 250,000, or approximately 80,000 to approximately 200,000, or approximately 90,000 to approximately 175,000, or approximately 100,000 to approximately 175,000, or approximately 90,000 to approximately 150,000, or approximately 100,000 to approximately 150,000, or approximately 100,000 to approximately 125,000, or approximately 90,000 to approximately 130,000, or approximately 90,000 to approximately 125,000, or approximately 85,000 to approximately 140,000, or approximately 85,000 to approximately 150,000, or more than approximately 85,000 to less than approximately 140,000. w It has.

[0095] In one embodiment of the present disclosure, the first polyethylene has a Z-average molecular weight M of at least 500,000, or greater than 500,000, or at least 550,000, or greater than 550,000, or at least 600,000, or greater than 600,000. z It has.

[0096] In one embodiment of the present disclosure, the first polyethylene has a Z-average molecular weight M of about 500,000 to about 800,000, or greater than 500,000 to about 800,000, or greater than 500,000 to less than 800,000, or about 500,000 to 750,000, or about 525,000 to about 750,000, or about 550,000 to about 750,000, or about 575,000 to about 750,000, or about 550,000 to about 725,000, or about 575,000 to about 725,000, or about 600,000 to about 700,000. z It has.

[0097] In an embodiment of the present disclosure, the first polyethylene has a molecular weight distribution Mw / Mn of 3.0 to 20.0, or greater than 3.0 to 18.0, or 3.5 to 16.0. w / Mn n It has.

[0098] In an embodiment of the present disclosure, the first polyethylene has a molecular weight distribution Mz / Mw of 8.0 to 12.0, or greater than 8.0 to 12.0, or greater than 8.5 to 12.0, or 9.0 to 12.0, or greater than 9.0 to less than 12.0, or 9.0 to 11.5, or 8.5 to 11.5, or 9.0 to 11.0, or 8.0 to 11.0, or 9.0 to 10.5, or 9.5 to 10.5. w / Mw n It has.

[0099] In an embodiment of the present disclosure, the first polyethylene has a molecular weight distribution Mz' / Mz of 3.5 to 8.0, or 4.0 to 8.0, or 4.0 to 7.5, or 4.0 to 7.0, or 4.5 to 7.5, or 4.5 to 7.0, or 4.5 to 6.5, or 5.0 to 7.0, or 5.5 to 7.0, or 5.0 to 6.5, or 5.5 to 6.5, or greater than 5.0 to less than 6.5, or 5.0 to 6.25, or 5.0 to 6.0. w / Mz n It has.

[0100] In one embodiment of the present disclosure, the first polyethylene is Log 10 [I6 / I2] / Log 10It has a stress index defined as [[6.48 / 2.16]], and this stress index is 1.60 - 2.00, or 1.65 - 2.00, or 1.70 - 2.00, or 1.75 - 1.95, or 1.75 - 1.90, or 1.80 - 1.95, or 1.80 - 1.90, or greater than 1.80 and less than 1.90.

[0101] In one embodiment of the present disclosure, the first polyethylene is characterized by having a high Mz of about 500,000 or more and a broad molecular weight distribution (Mw / Mn) of about 9.0 to about 12.0.

[0102] In an embodiment of the present disclosure, the first polyethylene has a compositional distribution breadth index CDBI of 40 - 75 wt%, or 50 - 70 wt%, or 55 - 70 wt%, or 55 - 65 wt% 50 and has.

[0103] In an embodiment of the present disclosure, the first polyethylene has a compositional distribution breadth index CDBI of 35 - 65 wt%, or 35 - 60 wt%, or 35 - 55 wt%, or 40 - 60 wt%, or 40 - 55 wt%, or 40 - 50 wt%, or greater than 40 wt% and less than 50 wt% 25 and has.

[0104] In one embodiment of the present disclosure, the first polyethylene has a unimodal profile in gel permeation chromatography (GPC). As used herein, the term "unimodal" is defined to mean that there is only one distinct significant peak or maximum in the GPC curve. Unimodal profiles include broad unimodal profiles. Unimodal profiles may also include shoulders or buried peaks that cannot be easily separated or deconvoluted into distinct, well - defined individual peaks in some cases.

[0105] In one embodiment of the present disclosure, the first polyethylene has a normal comonomer distribution profile as measured by GPC-FTIR. The distribution is described as “normal” if the comonomer incorporation decreases with molecular weight as measured by GPC-FTIR. In this specification, the term “normal comonomer distribution” is used to mean that the comonomer content of various polymer fractions is not substantially uniform across the molecular weight range of the first polyethylene, and that the higher molecular weight fraction has a proportionally lower comonomer content. The comonomer distribution is described as “flat” or “uniform” if the comonomer incorporation is nearly constant with respect to molecular weight as measured by GPC-FTIR. The terms “reverse comonomer distribution” and “partially reverse comonomer distribution” mean that in the GPC-FTIR data obtained for the copolymer, there is one or more high molecular weight components that have higher comonomer incorporation than one or more low molecular weight components. The term “reverse comonomer distribution” is used herein to mean that, over a molecular weight range of a first polyethylene, the comonomer content of various polymer fractions is not substantially uniform, and the higher molecular weight fractions have 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.”

[0106] In one embodiment, the first polyethylene contains catalyst residues that reflect the chemical composition of the catalyst formulation used to produce it. Those skilled in the art will understand that the catalyst residues are typically quantified by parts per million of metal, for example, in the first polyethylene. Here, 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 4 to 6 metals such as titanium, zirconium, hafnium, and vanadium.

[0107] In embodiments of the present disclosure, the first polyethylene has at least 0.050 ppm of titanium, or at least 0.100 ppm of titanium, or at least 0.250 ppm of titanium, or at least 0.300 ppm of titanium (based on the weight of the first polyethylene).

[0108] In embodiments of the present disclosure, the first polyethylene has (based on the weight of the first polyethylene) 0.050 to 3.0 ppm of titanium, or 0.050 to 2.5 ppm of titanium, or 0.050 to 2.0 ppm of titanium, or 0.050 to 1.5 ppm of titanium, or 0.050 to 1.0 ppm of titanium, or 0.100 to 3.0 ppm of titanium, or 0.100 to 2.5 ppm of titanium, or 0.100 to 2.0 ppm of titanium, or 0.100 to 1.5 ppm of titanium, or 0.100 to 1.0 ppm of titanium, or 0.250 to 3.0 ppm of titanium, or 0.250 to 2.0 ppm of titanium, or 0.250 to 1.5 ppm of titanium, or 0.250 to 1.0 ppm of titanium.

[0109] In embodiments of the present disclosure, the first polyethylene has at least 0.050 ppm of vanadium, or at least 0.100 ppm of vanadium, or at least 0.200 ppm of vanadium, or at least 0.250 ppm of vanadium, or at least 0.300 ppm of vanadium (based on the weight of the first polyethylene).

[0110] In embodiments of this disclosure, the first polyethylene contains (based on the weight of the first polyethylene) 0.050 to 3.0 ppm of vanadium, or 0.050 to 2.5 ppm of vanadium, or 0.050 to 2.0 ppm of vanadium, or 0.050 to 1.5 ppm of vanadium, or 0.050 to 1.0 ppm of vanadium, or 0.100 to 3.0 ppm of vanadium, or 0 It contains 0.100-2.5 ppm of vanadium, or 0.100-2.0 ppm of vanadium, or 0.100-1.5 ppm of vanadium, or 0.100-1.0 ppm of vanadium, or 0.200-3.0 ppm of vanadium, or 0.200-2.0 ppm of vanadium, or 0.200-1.5 ppm of vanadium, or 0.200-1.0 ppm of vanadium.

[0111] In one embodiment of the present disclosure, the first polyethylene is free from long-chain branching or contains no measurable amount of long-chain branching ("LCB"). 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: namely, nuclear magnetic resonance spectroscopy (NMR) (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).

[0112] In one embodiment of this disclosure, a first polyethylene is produced characterized by having a Mz greater than approximately 500,000, a molecular weight distribution (Mw / Mn) of approximately 9.0 to approximately 12.0, and a melt index greater than 0.5 g / 10 min. While we do not wish to be bound by theory, we have observed that these first polyethylene properties can be achieved by using the above-described multizone reactor system and carefully manipulating the amount and location of hydrogenation throughout the multizone reactor system, as shown in the attached examples.

[0113] <Second Polyethylene> In this disclosure, the second polyethylene includes a nucleating agent or a mixture of nucleating agents.

[0114] In embodiments of this disclosure, the second polyethylene is at least 0.950 g / cm³ 3 It is high-density polyethylene having a density of [density].

[0115] In this disclosure, high-density polyethylene (HDPE) is defined as having a concentration of at least 0.950 g / cm³. 3 It is defined as an ethylene homopolymer or ethylene copolymer having a density of .

[0116] In one embodiment of the present disclosure, the high-density polyethylene (HDPE) comprises one or more nucleating agents.

[0117] In embodiments of this disclosure, the second polyethylene is a polyethylene homopolymer composition comprising one or more ethylene homopolymer components.

[0118] In embodiments of this disclosure, the second polyethylene is at least 0.950 g / cm³ 3 This is a polyethylene homopolymer composition having a density of [density].

[0119] In embodiments of this disclosure, the second polyethylene is a polyethylene homopolymer composition comprising a first ethylene homopolymer and a second ethylene homopolymer, and embodiments of the first ethylene homopolymer and the second ethylene homopolymer are further described below.

[0120] In one embodiment of the present disclosure, the polyethylene homopolymer composition has a bimodal profile in gel permeation chromatography.

[0121] In one embodiment of the present disclosure, the polyethylene homopolymer composition has a multimodal profile in gel permeation chromatography.

[0122] In one embodiment of the present disclosure, the polyethylene homopolymer composition comprises one or more nucleating agents.

[0123] In embodiments of this disclosure, the polyethylene homopolymer composition is at least 0.950 grams / cubic centimeter (g / cm³). 3 ), or at least 0.955 grams / cubic centimeter (g / cm³). 3 ), or at least 0.960 grams / cubic centimeter (g / cm³). 3 It has a density of ).

[0124] In embodiments of this disclosure, the polyethylene homopolymer composition is 0.950 to 0.975 g / cm³. 3 , or 0.952~0.975 g / cm³ 3 , or 0.952~0.973 g / cm³ 3 , or 0.955~0.975 g / cm³ 3 , or 0.955~0.970 g / cm³ 3 It has a density of .

[0125] In embodiments of the present disclosure, the polyethylene homopolymer composition has a melt index I2 of 0.5 to 10.0 g / 10 min or 0.5 to 5.0 g / 10 min. In further embodiments of the present disclosure, the polyethylene homopolymer composition has a melt index I2 of 0.8 to 8.0 g / 10 min or 0.8 to 5 g / 10 min.

[0126] In one embodiment of the present disclosure, the polyethylene homopolymer composition has a molecular weight distribution (Mw / Mn) of about 3.0 to about 20.0.

[0127] Polyethylene homopolymer compositions can be produced by any of the following blending processes: 1) physical blending of particulate resins; 2) simultaneous feeding of different resins into a common extruder; 3) melt mixing (in any conventional polymer mixing apparatus); 4) solution blending; or 5) polymerization process using two or more reactors.

[0128] In one embodiment of the present disclosure, a polyethylene homopolymer composition is prepared by a solution polymerization process using two reactors operating under different polymerization conditions. This results in a homogeneous, in-situ blend of first and second ethylene homopolymer components. An example of this process is described in published U.S. Patent Application Publication 2006 / 0047078, the disclosure of which is incorporated herein by reference.

[0129] In one embodiment of the present disclosure, the polyethylene homopolymer composition is prepared by melt-blending a first and a second ethylene homopolymer in an extruder.

[0130] In one embodiment of the present disclosure, a polyethylene homopolymer composition is prepared by melt-blending the following two blend components in an extruder: (I) a first ethylene homopolymer in an amount of 90-70% by weight, with a melt index of I2 and a melt index of 0.955-0.965 g / cm³ of approximately 0.8-2.0 g / 10 min. 3A first ethylene homopolymer is a conventional polyethylene homopolymer composition (HDPE) having a density of, 10-30% by weight of (II) second ethylene homopolymer, with a melt index of I2 of approximately 15-30 g / 10 min and a melt index of 0.950-0.960 g / cm³. 3 A first ethylene homopolymer, which is a conventional polyethylene homopolymer composition (HDPE) having a density of .

[0131] In one embodiment of the present disclosure, a polyethylene homopolymer composition is prepared by a solution polymerization process using two reactors operating under different polymerization conditions. This results in a homogeneous, in-situ blend of ethylene polymer components produced in each reactor. Such a blend can be prepared, for example, in accordance with U.S. Patent Application Publication No. 2013 / 0225743 or No. 2008 / 0118749 and U.S. Provisional Application No. 63 / 023,270.

[0132] In one embodiment, the polyethylene homopolymer composition is an in-situ blend of a first ethylene homopolymer and a second ethylene homopolymer.

[0133] <First ethylene homopolymer> In one embodiment, the first ethylene homopolymer is prepared using a single-site catalyst.

[0134] In one embodiment, the first ethylene homopolymer is prepared using a phosphine imine catalyst.

[0135] In one embodiment, the first ethylene homopolymer is produced in a solution-phase polymerization reactor using a single-site catalyst.

[0136] In one embodiment, the first ethylene homopolymer is produced in a solution-phase polymerization reactor using a phosphine imine catalyst.

[0137] In one embodiment of the present disclosure, the first ethylene homopolymer has a melt index I2 lower than that of the second ethylene homopolymer.

[0138] In one embodiment of the present disclosure, the first ethylene homopolymer has a melt index I2 that is at least 50% lower than that of the second ethylene homopolymer.

[0139] In one embodiment of the present disclosure, the first ethylene homopolymer has a melt index I2 that is at least 10 times smaller than the melt index I2 of the second ethylene homopolymer.

[0140] In one embodiment of the present disclosure, the first ethylene homopolymer has a weight-average molecular weight M of the second ethylene homopolymer. w Higher weight-average molecular weight M w It has.

[0141] As will be recognized by those skilled in the art, the melt index I2 is generally inversely proportional to the molecular weight. Therefore, in one embodiment of the present disclosure, the first ethylene homopolymer has a relatively low melt index I2 (or, in other words, a relatively high molecular weight) compared to the second ethylene homopolymer.

[0142] In one embodiment of this disclosure, the first ethylene homopolymer is 0.950 to 0.975 g / cm³ 3 It has a density of . In another embodiment of the present disclosure, the first ethylene homopolymer has a density of 0.955 to 0.970 g / cm³. 3 It has a density of . In another embodiment of the present disclosure, the first ethylene homopolymer has a density of 0.955 to 0.965 g / cm³. 3 It has a density of .

[0143] In one embodiment of the present disclosure, the first ethylene homopolymer has a melt index I2 of about 0.01 to about 1.0 g / 10 min (g / 10 min).

[0144] In one embodiment of the present disclosure, the first ethylene homopolymer has a melt index I2 of about 0.1 to about 2.0 grams / 10 min (g / 10 min).

[0145] In embodiments of the present disclosure, the first ethylene homopolymer has a melt index I2 of about 0.1 to about 5.0 grams / 10 min (g / 10 min), or about 0.1 to about 10 grams / 10 min.

[0146] In one embodiment of the present disclosure, the molecular weight distribution (Mw / Mn) of the first ethylene homopolymer is about 1.7 to about 20.0. In further embodiments of the present disclosure, the molecular weight distribution (Mw / Mn) of the first ethylene homopolymer is about 2.0 to about 20.0, or about 1.7 to about 4.0, or about 2.0 to about 4.0.

[0147] In one embodiment of the present disclosure, the first ethylene homopolymer may itself contain one or more high-density ethylene homopolymer subcomponents.

[0148] In one embodiment of this disclosure, the first ethylene homopolymer constitutes 95 to 30% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the first ethylene homopolymer constitutes 95 to 40% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the first ethylene homopolymer constitutes 95 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the first ethylene homopolymer constitutes 95 to 60% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the first ethylene homopolymer constitutes 90 to 30% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the first ethylene homopolymer constitutes 90 to 40% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of the present disclosure, the first ethylene homopolymer constitutes 90 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of the present disclosure, the first ethylene homopolymer constitutes 90 to 60% by weight (wt%) of the total weight of the first and second ethylene homopolymers.

[0149] In one embodiment of the present disclosure, the first ethylene homopolymer constitutes 75 to 35% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the first ethylene homopolymer constitutes 65 to 40% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the first ethylene homopolymer constitutes 65 to 45% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the first ethylene homopolymer constitutes 65 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the first ethylene homopolymer constitutes 60 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers.

[0150] <Second ethylene homopolymer> In one embodiment, the second ethylene homopolymer is prepared using a single-site catalyst.

[0151] In one embodiment, the second ethylene homopolymer is prepared using a phosphine imine catalyst.

[0152] In one embodiment, the second ethylene homopolymer is produced in a solution-phase polymerization reactor using a single-site catalyst.

[0153] In one embodiment, the second ethylene homopolymer is produced in a solution-phase polymerization reactor using a phosphine imine catalyst.

[0154] In one embodiment of the present disclosure, the second ethylene homopolymer has a melt index I2 that is higher than that of the first ethylene homopolymer.

[0155] In one embodiment of the present disclosure, the second ethylene homopolymer has a melt index I2 that is at least 50% greater than the melt index I2 of the first ethylene homopolymer.

[0156] In one embodiment of the present disclosure, the second ethylene homopolymer has a melt index I2 that is at least 10 times greater than that of the first ethylene homopolymer.

[0157] In one embodiment of the present disclosure, the second ethylene homopolymer has a weight-average molecular weight M of the first ethylene homopolymer. w Lower weight-average molecular weight M w It has.

[0158] As those skilled in the art will recognize, the melt index I2 is generally inversely proportional to the molecular weight. Therefore, in one embodiment of the present disclosure, the second ethylene homopolymer has a relatively high melt index I2 (or, in other words, a relatively low molecular weight) compared to the first ethylene homopolymer.

[0159] In one embodiment of this disclosure, the second ethylene homopolymer is 0.950 to 0.975 g / cm³ 3 It has a density of . In another embodiment of the present disclosure, the second ethylene homopolymer has a density of 0.955 to 0.970 g / cm³. 3 It has a density of . In another embodiment of the present disclosure, the second ethylene homopolymer has a density of 0.955 to 0.965 g / cm³. 3 It has a density of .

[0160] In one embodiment of the present disclosure, the second ethylene homopolymer has a melt index I2 greater than about 100 g / 10 min, greater than about 250 g / 10 min, or greater than about 500 g / 10 min. In further embodiments, the second ethylene homopolymer may have a melt index greater than about 500 to about 25,000 g / 10 min, greater than about 500 to about 15,000 g / 10 min, greater than about 500 to about 10,000 g / 10 min, or greater than about 500 to about 8,500 g / 10 min.

[0161] In further embodiments, the second ethylene homopolymer may have a melt index of greater than 5.0 to about 50 g / 10 min, greater than 5.0 to about 40.0 g / 10 min, greater than 5.0 to about 30 g / 10 min, or greater than 5.0 to about 20.0 g / 10 min.

[0162] In one embodiment of the present disclosure, the molecular weight distribution (Mw / Mn) of the second ethylene homopolymer is about 1.7 to about 20.0. In further embodiments of the present disclosure, the molecular weight distribution (Mw / Mn) of the second ethylene homopolymer is about 2.0 to about 20.0, or about 1.7 to about 4.0, or about 2.0 to about 4.0.

[0163] In one embodiment of the present disclosure, the second ethylene homopolymer may itself contain one or more high-density ethylene homopolymer subcomponents.

[0164] In one embodiment of this disclosure, the second ethylene homopolymer constitutes 5 to 70% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the second ethylene homopolymer constitutes 5 to 60% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the second ethylene homopolymer constitutes 5 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the second ethylene homopolymer constitutes 5 to 40% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the second ethylene homopolymer constitutes 10 to 70% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of this disclosure, the second ethylene homopolymer constitutes 10 to 60% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of the present disclosure, the second ethylene homopolymer constitutes 10 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers. In one embodiment of the present disclosure, the second ethylene homopolymer constitutes 10 to 40% by weight (wt%) of the total weight of the first and second ethylene homopolymers.

[0165] In one embodiment of the present disclosure, the second ethylene homopolymer constitutes 25% to 65% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the second ethylene homopolymer constitutes 35% to 60% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the second ethylene homopolymer constitutes 35 to 55% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the second ethylene homopolymer constitutes 35 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers, or the second ethylene homopolymer constitutes 40 to 50% by weight (wt%) of the total weight of the first and second ethylene homopolymers.

[0166] <Nucleating agent> As used herein, the term “nucleating agent” is intended to convey its conventional meaning to those skilled in the art who prepare nucleated polyolefin compositions, namely, an additive that alters the crystallization behavior of a polymer when a polymer melt is cooled.

[0167] Reviews of nucleating agents are found in U.S. Patents No. 5,981,636, No. 6,465,551 and No. 6,599,971, the disclosures of which are incorporated herein by reference.

[0168] A commercially available nucleating agent that can be added to a second polyethylene (e.g., high-density polyethylene or polyethylene homopolymer composition) is dibenzylidene sorbital ester. Further examples of nucleating agents that can be added to the second polyethylene 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, the HHPA structure comprises a ring structure having six carbon atoms in the ring and two carboxylic acid groups which 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 the second polyethylene are disclosed in International Publication Nos. 2015 / 042561, 2015 / 042563, 2015 / 042562, and 2011 / 050042.

[0169] Another commercially available nucleating agent that can be added to the second polyethylene in one embodiment of this disclosure is talc (marketed as MICROTUFF® AG609).

[0170] A commercially available nucleating agent that can be added to the second polyethylene in one embodiment of this disclosure is IRGASTAB® NA287.

[0171] A commercially available nucleating agent that can be added to the second polyethylene in one embodiment of this disclosure is HPN(registered trademark) 210M.

[0172] Many of the nucleating agents mentioned above can be difficult to mix with the second polyethylene molecule that is nucleated. To mitigate this problem, it is known that dispersing agents such as zinc stearate are used.

[0173] In one embodiment of the present disclosure, the nucleating agent is well dispersed in the second polyethylene.

[0174] In one embodiment of the present disclosure, the amount of nucleating agent used is relatively small, 100 to 3000 ppm by weight (based on the weight of the polymer), so it will be understood by those skilled in the art that some care should 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 second polyethylene 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 the resin in solid form) is 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 the second polyethylene, and then the “masterbatch” is melt-mixed with the remaining bulk of the second polyethylene).

[0175] In one embodiment of the present disclosure, an additive such as a nucleating agent may be added to the second polyethylene in a “masterbatch” manner, where the term “masterbatch” refers to an embodiment in which the additive (e.g., a nucleating agent) is first melt-mixed with a small amount of the second polyethylene, and then the “masterbatch” is melt-mixed with the remaining bulk of the second polyethylene.

[0176] In one embodiment of the present disclosure, the second polyethylene comprises a nucleating agent or a mixture of nucleating agents.

[0177] In one embodiment of the present disclosure, the nucleating agent, or a mixture of nucleating agents, comprises a salt of a dicarboxylic acid.

[0178] In one embodiment, the nucleating agent, or a mixture of nucleating agents, comprises 1,2-cyclohexanedicarboxylic acid (CAS registry number 491589-22-1) as a calcium salt.

[0179] In one embodiment, the nucleating agent, or a mixture of nucleating agents, is 1,2-cyclohexanedicarboxylic acid (CAS registry number 491589-22-1) as a calcium salt mixed with zinc stearate.

[0180] In embodiments, a nucleating agent, or a mixture of nucleating agents, is added in an amount of 50-5,000 ppm, or 100-4,000 ppm, or 200-4,000 ppm, or 100-3,000 ppm, or 200-3,000 ppm, or 100-2,000 ppm, or 200-2,000 ppm, or 500-5,000 ppm, or 500-4,000 ppm, or 500-3,000 ppm, or 500-2,000 ppm, or 500-1,500 ppm, based on the weight of the second polyethylene.

[0181] <Other additives> The first or second polyethylene may contain conventional additives selected from the group consisting of: primary antioxidants (e.g., hindered phenols containing vitamin E); secondary antioxidants (e.g., phosphites and phosphonites); ultraviolet absorbers and light stabilizers; processing aids (e.g., fluoroelastomers and / or polyethylene glycol bonding processing aids); slip agents; fillers, anti-blocking agents and reinforcing agents; or other additives.

[0182] Further details of other additives added to the first or second polyethylene in embodiments of this disclosure are given below.

[0183] In embodiments of this disclosure, other additives may also be used in amounts of 100 to 5,000 ppm, 100 to 3,000 ppm, 200 to 3,000 ppm, or 200 to 2,000 ppm (based on the weight of the polymer).

[0184] <Primary antioxidant> In embodiments of this disclosure, the primary antioxidant is selected from, for example, alkylated monophenols such as: 2,6-di-tert-butyl-4-methylphenol; 2-tert-butyl-4,6-dimethylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,6-di-tert-butyl-4-n-butylphenol; 2,6-di-tert-butyl-4-isobutylphenol; 2,6-dicyclopentyl-4-methylphenol; 2-(alpha-methylcyclohexyl)-4,6-dimethylphenol; 2,6-di-octadecyl-4-methylphenol; 2,4,6-tricyclohexylphenol; and 2,6-di-tert-butyl-4-methoxymethylphenol.

[0185] In embodiments of this disclosure, the primary antioxidant is selected from, for example, alkylated hydroquinones such as: 2,6-di-tert-butyl-4-methoxyphenol; 2,5-di-tert-butylhydroquinone; 2,5-di-tert-amyl-hydroquinone; and 2,6-diphenyl-4-octadecyloxyphenol.

[0186] In embodiments of this disclosure, the primary antioxidant is selected from, for example, the following hydroxylated thiodiphenyl ethers: 2,2'-thio-bis-(6-tert-butyl-4-methylphenol); 2,2'-thio-bis-(4-octylphenol); 4,4'-thio-bis-(6-tert-butyl-3-methylphenol); and 4,4'-thio-bis-(6-tert-butyl-2-methylphenol).

[0187] In embodiments of this disclosure, a primary antioxidant is selected from, for example, alkylidene bisphenols such as: 2,2'-methylene-bis-(6-tert-butyl-4-methylphenol); 2,2'-methylene-bis-(6-tert-butyl-4-ethylphenol); 2,2'-methylene-bis-(4-methyl-6-(alpha-methylcyclohexyl)phenol); 2,2'-methylene-bis-(4-methyl-6-cyclohexylphenol); 2,2'-methylene-bis-(6-nonyl-4-methyl Phenol); 2,2'-methylene-bis-(6-nonyl-4-methylphenol); 2,2'-methylene-bis-(6-(alpha-methylbenzyl)-4-nonylphenol); 2,2'-methylene-bis-(6-(alpha,alpha-dimethylbenzyl)-4-nonylphenol); 2,2'-methylene-bis-(4,6-di-tert-butylphenol); 2,2'-ethylidene-bis-(6-tert-butyl-4-isobutylphenol); 4,4'-methylene-bis-(2,6-di-tert-butylphenol phenol); 4,4'-methylene-bis-(6-tert-butyl-2-methylphenol); 1,1-bis-(5-tert-butyl-4-hydroxy-2-methylphenol)butane; 2,6-di-(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol; 1,1,3-tris-(5-tert-butyl-4-hydroxy-2-methylphenyl)butane; 1,1-bis-(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-dodecyl-mercaptobutane; ethylene Recall-bis-(3,3,-bis-(3'-tert-butyl-4'-hydroxyphenyl)-butyrate)-di-(3-tert-butyl-4-hydroxy-5-methylphenyl)-dicyclopentadiene; di-(2-(3'-tert-butyl-2'hydroxy-5'methylbenzyl)-6-tert-butyl-4-methylphenyl) terephthalate; and other phenols such as monoacrylate esters of bisphenols, including ethylidenebis-2,4-di-t-butylphenol monoacrylate.

[0188] In embodiments of this disclosure, the primary antioxidant may be used in amounts of 100 to 5,000 ppm, 100 to 3,000 ppm, 200 to 3,000 ppm, or 200 to 2,000 ppm (based on the weight of the polymer).

[0189] <Secondary antioxidant> In embodiments of this disclosure, the secondary antioxidant is selected from, for example, the following phosphites and phosphonites: triphenyl phosphite; diphenyl alkyl phosphate; phenyl dialkyl phosphate; tris(nonylphenyl) phosphite; trilauryl phosphite; trioctadecyl phosphite; distearyl pentaerythritol diphosphite; tris(2,4-di-tert-butylphenyl) phosphite; diisodecyl pentaerythritol diphosphite; 2,4,6-tri-tert-butylphenyl-2-butyl-2-ethyl-1,3-propanediol phosphite; bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite; tristearyl sorbitol triphosphite; and tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylenediphosphonite.

[0190] In embodiments of this disclosure, the secondary antioxidant is selected from, for example, the following hydroxylamines and amine oxides: N,N-dibenzylhydroxylamine; N,N-diethylhydroxylamine; N,N-dioctylhydroxylamine; N,N-dilaurylhydroxylamine; N,N-ditetradecylhydroxylamine; N,N-dihexadecylhydroxylamine; N,N-dioctadecylhydroxylamine; N-hexadecyl-N-octadecylhydroxylamine; N-heptadecyl-N-octadecylhydroxylamine; and N,N-dialkylhydroxylamine derived from hydrogenated tallowamines. Similar amine oxides are also suitable.

[0191] In embodiments of this disclosure, secondary antioxidants may also be used in amounts of 100 to 5,000 ppm, 100 to 3,000 ppm, 200 to 3,000 ppm, or 200 to 2,000 ppm (based on the weight of the polymer).

[0192] <UV absorbers and light stabilizers> In embodiments of the present disclosure, the ultraviolet absorber or light stabilizer is selected from, for example, the following 2-(2'-hydroxyphenyl)-benzotriazole derivatives: 5'-methyl-,3'5'-di-tert-butyl-,5'-tert-butyl-,5'(1,1,3,3-tetramethylbutyl)-,5-chloro-3',5'-di-tert-butyl-,5-chloro-3'-tert-butyl-5'-methyl-3'-sec-butyl-5'-tert-butyl-,4'-octoxy,3',5'-ditert-amyl-3',5'-bis-(alpha,alpha-dimethylbenzyl)-derivatives.

[0193] In embodiments of this disclosure, the ultraviolet absorber or light stabilizer is selected from, for example, the following 2-hydroxybenzophenones: 4-hydroxy-4-methoxy-,4-octoxy,4-decyloxy-,4-dodecyloxy-,4-benzyloxy,4,2',4'-trihydroxy- and 2'-hydroxy-4,4'-dimethoxy derivatives.

[0194] In embodiments of this disclosure, the ultraviolet absorber or light stabilizer is selected from, for example, the following sterically hindered amines: bis(2,2,6,6-tetramethylpiperidyl)-sebacate; bis-5(1,2,2,6,6-pentamethylpiperidyl)-sebacate; n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate bis(1,2,2,6,6-pentamethylpiperidyl) ester; 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxy-piperidine and cobalt Condensation products of citric acid; condensation products of N,N'-(2,2,6,6-tetramethylpiperidyl)-hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-s-triazine; tris-(2,2,6,6-tetramethylpiperidyl)-nitrilotriacetate, tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarbonate; and 1,1'(1,2-ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinon). These amines are typically called HALS (Hindered Amines Light Stabilizing) and include butanetetracarboxylic acid 2,2,6,6-tetramethylpiperidinol ester. Such amines include hydroxylamines derived from hindered amines. For example, di(1-hydroxy-2,2,6,6-tetramethylpiperidine-4-yl) sebacate; 1-hydroxy-2,2,6,6-tetramethyl-4-benzoxypiperidine; 1-hydroxy-2,2,6,6-tetramethyl-4-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)-piperidine; and N-(1-hydroxy-2,2,6,6-tetramethyl-piperidine-4-yl)-ε-caprolactam.

[0195] <Slip agent> In embodiments of this disclosure, the slip agent is selected from oleamide, erucamide, stearamide, and behenamide.

[0196] <Fillers, anti-blocking agents, and reinforcing agents> In embodiments of the present disclosure, the filler, anti-blocking agent, or reinforcing agent is selected from calcium carbonate, diatomaceous earth, natural silica and synthetic silica, silicates, glass fibers, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and metal hydroxides, carbon black, and graphite.

[0197] <Other additives> In embodiments of this disclosure, other additives are selected from plasticizers, epoxidized vegetable oils such as epoxidized soybean oil, lubricants, emulsifiers, pigments, fluorescent whitening agents, flame retardants, antistatic agents, antifogging agents, foaming agents, and thio synergists such as dilauryl thiodipropionate or distearyl thiodipropionate.

[0198] 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]

[0199] <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.

[0200] <density> The polymer density was determined using ASTM D792-13 (November 1, 2013).

[0201] <Melt Index> The melt index of the polymer was determined using ASTM D1238 (August 1, 2013). Melt index: I2, I6, I 10 , and I 21These 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.

[0202] <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 (1,000 ppm solution of the desired element (purity over 99%)). 1 mL of the solution (of the target element) was pipetteed onto a 15 mm × 800 mm rectangular paper filter and air-dried. The filter paper was then placed in a 1.4 mL polyethylene irradiation vial and analyzed using the NAA system. Use the standard to determine the sensitivity (counts / μg) of the NAA procedure.

[0203] <Gel Permeation Chromatography (GPC)> The polymer sample (polymer) solution (1 - 3 mg / mL) was prepared by heating the polymer in 1,2,4 - trichlorobenzene (TCB) and rotating it on a wheel at 150 °C for 4 hours in an oven. 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 solution was chromatographed on a PL220 high - temperature chromatography unit equipped with four Shodex columns (HT803, HT804, HT805, and HT806), using TCB as the mobile phase, at a flow rate of 1.0 mL / min and 140 °C, and a differential refractive index (DRI) was used 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), the Mark - Houwink equation was used to convert the polystyrene molecular weight to the polyethylene molecular weight. The raw GPC data was processed with CIRRUS GPC software to generate the molar mass average (M n , M w , M z ) and the molar mass distribution (e.g., polydispersity M w / M n ). In the technical field of polyethylene, the commonly used term equivalent to GPC is SEC, i.e., size - exclusion chromatography.

[0204] <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. To stabilize the polymer against oxidative degradation, the 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 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. To protect the SEC columns from oxidative degradation, BHT was added to the mobile phase at a concentration of 250 ppm. 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.

[0205] <Short-chain branching: GPC-FTIR> The short-chain branches per 1000 carbon atoms are measured for copolymer fractions of different molecular weights. When plotted on a semi-logarithmic scale graph, the slope line (with the logarithmic horizontal X-axis from the low molecular weight fraction to the high molecular weight fraction and the vertical Y-axis being the number of short-chain branches) represents the distribution of short-chain branches in fractions of different molecular weights determined by Fourier transform infrared (FTIR) spectroscopy. In the GPC-FTIR method, the total methyl content including the methyl groups located at the ends of each polymer chain, i.e., methyl end groups, is measured. Therefore, the raw GPC-FTIR data needs to be corrected by subtracting the contribution from the methyl end groups. More specifically, the raw GPC-FTIR data overestimates the amount of short-chain branches (SCB), and this overestimation increases as the molecular weight (M) decreases. In the present disclosure, the raw GPC-FTIR data was corrected using 2-methyl correction. At a given molecular weight (M), the number of methyl end groups (N E ) is calculated using the following formula; N E = 28000 / M, and N E (M-dependent) is subtracted from the raw GPC-FTIR data to create the SCB / 1000C (2-methyl corrected) GPC-FTIR data.

[0206] <Unsaturation content> The amount of unsaturated groups, i.e., double bonds, in the polyethylene composition was determined according to ASTM D3124-98 (Vinylidene unsaturation, issued in March 2011) and ASTM D6248-98 (Vinyl and trans unsaturations, issued in July 2012). The ethylene interpolymer sample was: a) first subjected to carbon disulfide extraction to remove additives that may interfere with the analysis; b) the sample (pellets, film, or granules) was pressed into a plaque of uniform thickness (0.5 mm); c) the plaque was analyzed by FTIR.

[0207] <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).

[0208] <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.

[0209] <Dynamic mechanical analysis (DMA)> Vibrational shear measurements were performed at small strain amplitudes, and linear viscoelastic functions were obtained in a frequency range of 0.02 to 126 rad / s at 190°C in an N2 atmosphere, with a strain amplitude of 10%, and 5 points per 10 points. Frequency sweep experiments were performed using a TA Instruments DHR3 stress-controlled rheometer with a cone angle of 5°, a truncated head of 137 μm, and a conical plate shape with a diameter of 25 mm. In these experiments, sinusoidal strain waves were applied, and the stress response was analyzed in terms of linear viscoelastic functions. The zero shear rate viscosity (η0) based on the DMA frequency sweep results was predicted by the Ellis model (see RBBird et al., "Dynamics of Polymer Liquids. Volume 1: Fluid Mechanics," Wiley-Interscience Publications (1987), p. 228) or the Carreau-Yasuda model (see K. Yasuda (1979) PhD Thesis, IT Cambridge). Dynamic rheological data was analyzed using rheometric software (i.e., Rheometrics RHIOS V4.4 or Orchestrator Software) to determine the melt modulus G' (G''=500) at a reference melt viscosity (G'') value of G''=500 Pa. Where necessary, values ​​were obtained by interpolation between available data points using Rheometrics software.

[0210] 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).

[0211] <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

[0212] 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.

[0213] <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.

[0214] <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)).

[0215] <CYTSAF / TREF(CTREF)> The "composition distribution index" (hereinafter referred to as CDBI) of polymer samples 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 value 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).

[0216] <Hexane extract> The hexane extract was determined in accordance with Federal Regulations 21 CFR §177.1520 Para(c)3.1 and 3.2. The amount of hexane extractable substances in the sample was determined by weight measurement.

[0217] <Film optics> The film optical properties were measured as follows: haze and transparency were measured in accordance with ASTM D1003-13 (November 15, 2013).

[0218] <Film mechanical properties> Tensile tests in both the machine direction and the transverse direction (MD and TD respectively) were carried out in accordance with ASTM D882 (ASTM D882-10 and ASTM D882-12). The width of the test specimens used for measuring the tensile properties was 1.0 inches. The initial draw rate was 1.0 inch / min up to 5% strain, and then the speed was increased to 20.0 inches / min until rupture. The grip interval was 2.0 inches. The measured mechanical properties were tensile break stress (reported in MPa), strain at yield (%), yield stress (MPa), strain at break (%), break stress (MPa). The modulus of elasticity (MPa) was measured using test specimens with a width of 1.0 inches and a grip interval of 2 inches at a test speed of 1.0 inch / min.

[0219] <Film heat shrinkage rate (%)> The shrinkage rate of the film was measured using a 10×10 cm film test specimen placed in an oven in air and measured at 120 °C for 5 minutes. The lengths of the film in the machine direction and the transverse direction of the heated film were compared with the original film, and the relative decrease was reported as the shrinkage rate. (% shrinkage rate = L initial -L final ) / L initial (where L initial and L final are the length before heat treatment and the length after heat treatment).

[0220] <Film thickness> The film thickness of the stretched multilayer film was measured in accordance with ASTM D6988-13.

[0221] <First Polyethylene> For use as the first polyethylene, an ethylene copolymer was substantially prepared in accordance with the disclosure of Canadian Patent Application No. 3,102,574, both pending. The ethylene copolymer (for use as the first polyethylene) was prepared in a multizone solution polymerization process in which three polymerization zones, each defined by a different polymerization reactor, were configured in series with respect to each other (see Figure 1). The first polymerization zone was defined by a first tubular reactor (reactor 1), the second polymerization zone was defined by an optionally agitated tank reactor (reactor 2), and the third polymerization zone was defined by a second tubular reactor (reactor 3). Each reactor has an inlet into which the process flow enters the reactor and an outlet into which the process flow exits the reactor. In the case of a tubular reactor, the inlet is located at the upstream end of the reactor and the outlet is located at the downstream end of the reactor. In this polymerization process, the tank reactor (reactor 2) that receives the process flow from the first tubular reactor is an optionally stirred tank reactor, but it is operated without stirring and therefore functions as a kind of plug-flow reactor. In this disclosure, the optionally equipped tank reactor is referred to as operating in "plug-flow mode" when the stirrer is stopped.

[0222] The first tubular reactor (reactor 1) was a pipe with a diameter of 6 inches, a length of 36.6 meters, and a total volume of 500 liters. The polymerization reaction was started by injecting the Ziegler-Natta polymerization catalyst, along with the solvent (cyclohexane), hydrogen, ethylene, and 1-butene, into the inlet of the first tubular reactor (reactor 1) (position A in Figure 1), which was the starting point of the first tubular reactor (reactor 1) (Note: The Ziegler-Natta polymerization catalyst components were combined just upstream of the inlet of the first tubular reactor, as will be further explained below; not shown in Figure 1). Hydrogen was also supplied to a second position of the first tubular reactor (position B in Figure 1), which was downstream from the inlet of the first tubular reactor and located approximately 50% along the length of the first tubular reactor. In this solution-phase polymerization process, as the process flow moved from the first tubular reactor to the tank reactor and then to the second tubular reactor, the polymerization reaction continued throughout the entire length of the first tubular reactor, then in the tank reactor (reactor 2), and then throughout the entire length of the second tubular reactor. The polymerization reaction temperature profile was monitored using eight temperature indicators positioned along the first tubular reactor.

[0223] Reactor 2 was a tank (or "autoclave") reactor with a volume of 3,640 liters, protected by a safety valve set to 19.1 MPa. The tank reaction vessel was constructed of carbon steel, and the inlet nozzle was Monel-plated. Four baffles, 11.4 cm wide, were positioned 6.35 cm vertically from the wall at 90° angles to each other to prevent circulation within the vessel caused by the presence of a stirrer. The stirrer consisted of five hubs, each with six impeller blades, and was spaced evenly across the height of the reaction vessel. The tank reactor's stirrer was not used during this solution-phase polymerization process (it was present but not turned on), and therefore the tank reactor operated in "plug-flow mode". Temperature indicators placed throughout the tank reactor were used to monitor the polymerization reaction temperature profile. The tank reaction vessel was also traced with high-pressure steam.

[0224] Reactor 3 was a second tubular reactor with a 10-inch diameter pipe and a length of 53 meters. Temperature indicators were placed throughout the tank reactor to monitor the polymerization reaction temperature profile.

[0225] Polymerization in the solution polymerization process was stopped by adding a catalyst deactivator to the outlet flow leaving the outlet of the second tubular reactor (reactor 3). The catalyst deactivator used was pelargonic acid.

[0226] Using a solution absorbent (activated aluminum), trace amounts of metal residues (vanadium and zirconium) from the Ziegler-Natta catalyst are removed.

[0227] A two-stage defoliation process was employed to recover the ethylene copolymer from the process solvent. Specifically, two vapor / liquid separators were used, and the second bottom flow (from the second V / L separator) was passed through a gear pump / pelletizer combination.

[0228] DHT-4V (hydrotalcite), supplied by Kyowa Chemical Industry Co., Ltd. (Tokyo, Japan), can be used as a passivator or acid scavenger in solution processes. A slurry of DHT-4V in the process solvent may be added before the first V / L separator.

[0229] The resin product is pelletized using two single-screw extruders, and then the pellets are deactivated in a stripper supplied with nitrogen and steam.

[0230] Before pelletizing, the ethylene copolymer was stabilized by adding 1,000 ppm of IRGANOX® 1010 (primary antioxidant) and 1,000 ppm of IRGAFOS® 168 (secondary antioxidant) based on the weight of the ethylene copolymer composition. The antioxidants were dissolved in a process solvent and added between the first and second V / L separators.

[0231] The Ziegler-Natta polymerization catalyst used to carry out the polymerization reaction was supplied to the inlet of the first tubular reactor and consisted of the following three components: (i) vanadium precatalyst compound, VOCl3; (ii) titanium tetrachloride, TiCl4, which is a titanium precatalyst component; and (iii) triethylaluminum, (C2H5)3Al, which is a cocatalyst compound. The VOCl3 and TiCl4 compounds were first mixed (in cyclohexane) in a weight ratio of 80 / 20, and then mixed with triethylaluminum at the inlet of the first tubular reactor (position A in Figure 1) immediately before being injected into the first tubular reactor.

[0232] Table 1 shows the details of the solution-phase polymerization carried out in a multi-zone reaction system. Table 2 shows the details of the obtained ethylene copolymer.

[0233] [Table 1]

[0234] [Table 2]

[0235] <Second Polyethylene> For use as a second polyethylene, polyethylene homopolymer compositions were prepared substantially in accordance with the disclosures of U.S. Patent Application Publication No. 2013 / 0225743 or 2008 / 0118749 and the teachings of U.S. Provisional Application No. 63 / 023,270.

[0236] The polyethylene homopolymer composition used in this example is as follows: Polyethylene homopolymer composition "C1": Density 0.968 g / cm³ 3 Melt index (I2) 2.0 g / 10 min, molecular weight distribution 8.8; and polyethylene homopolymer composition "C2": density 0.966 g / cm³ 3 Melt index (I2) 1.2g / 10min, molecular weight distribution (M w / M n 8.5. It is commercially available from NOVA Chemicals as SURPASS(registered trademark) HPs167-AB.

[0237] Further details of the polyethylene homopolymer composition are shown in Table 3.

[0238] [Table 3]

[0239] <Addition of nucleating agents> Polyethylene homopolymer compositions ("C1" or "C2") were nucleated using 1,200 ppm (parts per million by weight) of HYPERFORM® HPN-20E, commercially available from Milliken. The nucleating agent has been reported to be a combination of a) the calcium salt of HHPA and b) zinc stearate (in a 1 / 2 weight ratio). To generate nuclei in the polyethylene homopolymer compositions, an HPN-20E masterbatch was prepared, the masterbatch was allowed to descend to an appropriate level, and then melt-blended into the polyethylene homopolymer compositions.

[0240] Alternatively, ethylene copolymer ("EC2") was nucleated using 4,000 ppm (parts per million by weight) of MICROTUFF AG609, commercially available from Specialty Minerals. To generate ethylene copolymer nuclei, a masterbatch containing MICROTUFF AG609 was prepared, the masterbatch was allowed to descend to an appropriate level, and then melt-blended with the ethylene copolymer.

[0241] <The third type of polyethylene> The linear low-density polyethylene (LLDPE1) used as the third polyethylene in this embodiment is SURPASS FPs123-A, an ethylene copolymer containing ethylene and 1-octene, with a density of 0.923 g / cm³. 3 It also has a melt index (I2) of 1.3 g / 10 min and is commercially available from NOVACchemicals.

[0242] The medium-density polyethylene (MDPE1) used as the third polyethylene in this example is SURPASS FPs236-A, which is an ethylene copolymer containing ethylene and 1-octene, with a density of 0.936 g / cm 3 and a melt index (I2) of 2.9 g / 10 min, and is commercially available from NOVA Chemicals.

[0243] Another medium-density polyethylene (MDPE2) used as the third polyethylene in this example is SURPASS RMs341-U, which is an ethylene copolymer containing ethylene and 1-octene, with a density of 0.941 g / cm 3 and a melt index (I2) of 3.5 g / 10 min, and is commercially available from NOVA Chemicals.

[0244] <A. Preparation of Unstretched Film (or "Base Structure")> The multilayer (three-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 inlet of the die. The multilayer web extruded from the die is fixed to a casting roll or a cooling roll using an air knife and an edge pinner, and is rapidly cooled on the cooling roll. The primary cooling roll temperature was set at 76°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 15% by weight of the total polymer used in the film structure and a core layer containing 70% by weight of the total polymer used in the film structure is described as a 15 / 70 / 15 structure.

[0245] As shown in Table 4, several three-layer base film structures with structures ranging from 10 / 80 / 10 to 16 / 68 / 16 were prepared using various polyethylene materials. For layers containing a blend of two polyethylene materials (e.g., a core layer containing an ethylene copolymer and a nucleated ethylene homopolymer composition), the layers were cast as polymer blends by blending pellets immediately before extrusion using an in-line gravimetric blending system.

[0246] [Table 4]

[0247] From each of these base multilayer film structures (base film structure numbers 1 to 15), biaxially oriented polyethylene (BOPE) films were prepared using the procedure described in Part B below.

[0248] <Part B. Preparation of BOPE Film - Sequential Stretching> BOPE film structures were fabricated using a sequential stretching process on a tenter frame biaxial stretching line. First, stretching / orientation was performed in the machine direction. Then, the "oriented" sheets were stretched transversely.

[0249] Machine direction orientation (MDO) was performed using either a single-stage or multi-stage short-gap stretching process at temperatures up to 245°F and a stretch ratio of approximately 6.5:1. Transverse direction orientation (TDO) was performed in multiple zones (preheating zone, stretching zone, annealing zone, and finally a single cooling zone). The temperature in the TDO stretching zone was up to 280°F, and the stretch ratio was up to approximately 5.5:1.

[0250] 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 film's crystalline melting temperature (Tm). 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 and 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 5 outlines the common process conditions used in tenter frame processes.

[0251] [Table 5]

[0252] All base film structures (base film structure numbers 1-15) in Table 4 were successfully converted to BOPE film structures (BOPE film structure numbers 1-15). The selected properties of these biaxially oriented multilayer film structures are shown in Table 6.

[0253] [Table 6]

[0254] As can be seen from the data shown in Table 6, when the biaxially oriented film structure has a core layer containing ethylene copolymer and nucleated polyethylene homopolymer composition, the film structure exhibits very good haze and transparency: haze is less than 15% and transparency exceeds 80%. Notably, good haze and transparency were maintained even when the amount of nucleated polyethylene homopolymer composition in the core layer was very small (for example, good haze and transparency were maintained even when the core layer contained a blend of at least 95% by weight of ethylene copolymer and 5% by weight or less of nucleated polyethylene homopolymer composition (see BOPE films numbers 6, 7, 8, 9, 14 and 15)). As long as the core layer contained ethylene copolymer and nucleated polyethylene homopolymer composition, good haze and transparency values ​​were maintained even in film structures with different materials in the first and second adjacent layers (e.g., skin layers). For comparison, when the core layer consisted solely of nucleated ethylene copolymer (films 1, 2, and 11), or when the core layer consisted of a blend of ethylene copolymer and nucleated polyethylene homopolymer composition (film 10), or when the core layer consisted of a blend of ethylene copolymer and nucleated ethylene copolymer (film 13), one or both of the haze and transparency of the BOPE film structure were adversely affected.

[0255] Non-limiting embodiments of this disclosure include:

[0256] Embodiment A. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene and Includes, A polyethylene homopolymer composition is a biaxially oriented polyethylene film structure comprising a nucleating agent or a mixture of nucleating agents.

[0257] Embodiment B. The polyethylene homopolymer composition is 0.952 to 0.975 g / cm³. 3 A biaxially oriented polyethylene film structure according to Embodiment A, having a density of [value].

[0258] Embodiment C. A biaxially oriented polyethylene film structure according to Embodiment A or B, wherein the polyethylene homopolymer composition has a melt index of 0.5 to 5 g / 10 min.

[0259] Embodiment D. A polyethylene homopolymer composition is i) 0.950~0.975 g / cm³ 3 A first ethylene homopolymer having a density of 5-70% by weight, ii) 0.950~0.975 g / cm³ 3 A second ethylene homopolymer having a density of 95-30% by weight and Includes, A biaxially oriented polyethylene film structure according to Embodiment A, B, or C, wherein the ratio of the melt index I2 of the second ethylene homopolymer to the melt index I2 of the first ethylene homopolymer is at least 10.

[0260] Embodiment E. The first polyethylene is 0.941~0.962 g / cm³. 3 A biaxially oriented polyethylene film structure according to Embodiment A, B, C, or D, having a density of the above.

[0261] Embodiment F. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, or E, wherein the first polyethylene has a melt index of 0.5 to 5.0 g / 10 min.

[0262] Embodiment G. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, or F, wherein the first polyethylene has a molecular weight distribution of 3.0 to 20.0.

[0263] Embodiment H. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, or F, wherein the first polyethylene has a molecular weight distribution of 8.5 to 20.0.

[0264] Embodiment I. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, or H, wherein the first polyethylene has a Z-average molecular weight Mz of at least 500,000 g / mol.

[0265] Embodiment J. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, or I, wherein the polyethylene homopolymer composition comprises 100 to 3,000 ppm (based on the weight of the polyethylene homopolymer composition) of a nucleating agent or a mixture of nucleating agents.

[0266] Embodiment K. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, or J, wherein the nucleating agent or mixture of nucleating agents comprises a salt of a dicarboxylic acid.

[0267] Embodiment L. Three adjacent layers each, i) 70-99.5% by weight of the first polyethylene, ii) 0.5-30% by weight of the second polyethylene and A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, or K, including the above.

[0268] Embodiment M. Three adjacent layers each, i) 90-99.5% by weight of the first polyethylene, ii) 0.5-10% by weight of the second polyethylene and A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, or K, including the above.

[0269] Embodiment N. 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 haze value of less than 15%.

[0270] Embodiment 0. A biaxially oriented polyethylene film structure according to Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or N, having a transparency value exceeding 80%.

[0271] Embodiment P. 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, The core layer, the first skin layer, and the second skin layer are each: i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A polyethylene homopolymer composition having a density of a second polyethylene and Includes, A polyethylene homopolymer composition is a biaxially oriented polyethylene film structure comprising a nucleating agent or a mixture of nucleating agents.

[0272] Embodiment Q. The polyethylene homopolymer composition is 0.952 to 0.975 g / cm³. 3 A biaxially oriented polyethylene film structure according to embodiment P, having a density of [value].

[0273] Embodiment R. A biaxially oriented polyethylene film structure according to Embodiment P or Q, wherein the polyethylene homopolymer composition has a melt index of 0.5 to 5 g / 10 min.

[0274] Embodiment S. A polyethylene homopolymer composition is i) 0.950~0.975 g / cm³ 3 A first ethylene homopolymer having a density of 5-70% by weight, ii) 0.950~0.975 g / cm³ 3 A second ethylene homopolymer having a density of 95-30% by weight and Includes, A biaxially oriented polyethylene film structure according to Embodiment P, Q, or R, wherein the ratio of the melt index I2 of the second ethylene homopolymer to the melt index I2 of the first ethylene homopolymer is at least 10.

[0275] Embodiment T. The first polyethylene is 0.941~0.962 g / cm³ 3 A biaxially oriented polyethylene film structure according to embodiment P, Q, R, or S, having a density of .

[0276] Embodiment U. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, or T, wherein the first polyethylene has a melt index of 0.5 to 5.0 g / 10 min.

[0277] Embodiment V. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, or U, wherein the first polyethylene has a molecular weight distribution of 3.0 to 20.0.

[0278] Embodiment W. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, or U, wherein the first polyethylene has a molecular weight distribution of 8.5 to 20.0.

[0279] Embodiment X. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, or W, wherein the first polyethylene has a Z-average molecular weight Mz of at least 500,000 g / mol.

[0280] Embodiment Y. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, W, or X, wherein the polyethylene homopolymer composition comprises 100 to 3,000 ppm (based on the weight of the polyethylene homopolymer composition) of a nucleating agent or a mixture of nucleating agents.

[0281] Embodiment Z. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, W, X, or Y, wherein the nucleating agent or mixture of nucleating agents comprises a salt of a dicarboxylic acid.

[0282] Embodiment AA. Each of the core layer, the first skin layer, and the second skin layer is: i) 70-99.5% by weight of the first polyethylene, ii) 0.5-30% by weight of the second polyethylene and A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, W, X, Y, or Z, including the above.

[0283] Embodiment BB. Each of the core layer, the first skin layer, and the second skin layer is, i) 90-99.5% by weight of the first polyethylene, ii) 0.5-10% by weight of the second polyethylene and A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, W, X, Y, or Z, including the above.

[0284] Embodiment CC. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, W, X, Y, Z, AA, or BB, having a haze value of less than 15%.

[0285] Embodiment DD. A biaxially oriented polyethylene film structure according to Embodiments P, Q, R, S, T, U, V, W, X, Y, Z, AA, BB, or CC, having a transparency value exceeding 80%.

[0286] Embodiment EE. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A second polyethylene is a high-density polyethylene having a density of Includes, High-density polyethylene contains a nucleating agent or a mixture of nucleating agents. The biaxially oriented polyethylene film structure has a haze value of less than 15%. Biaxially oriented polyethylene film structure.

[0287] Embodiment FF. 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, The core layer, the first skin layer, and the second skin layer are each: i) 50-99.5% by weight of the first polyethylene, and the first polyethylene is 0.940 g / cm³ 3 A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ 3 A second polyethylene is a high-density polyethylene having a density of Includes, High-density polyethylene contains a nucleating agent or a mixture of nucleating agents. The biaxially oriented polyethylene film structure has a haze value of less than 15%. Biaxially oriented polyethylene film structure. [Industrial applicability]

[0288] The product offered is a biaxially oriented polyethylene (BOPE) film structure containing at least three layers. The BOPE film structure possesses good optical properties and excellent recyclability, making it suitable for a variety of packaging applications.

Claims

1. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, the first polyethylene being 0.940 g / cm³ ３ A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ ３ A polyethylene homopolymer composition having a density of a second polyethylene and Includes, A polyethylene homopolymer composition contains a nucleating agent or a mixture of nucleating agents. Biaxially oriented polyethylene film structure.

2. The polyethylene homopolymer composition is 0.952 to 0.975 g / cm³. ３ A biaxially oriented polyethylene film structure according to claim 1, having the density of [a specific density].

3. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene homopolymer composition has a melt index of 0.5 to 5 g / 10 min.

4. A polyethylene homopolymer composition i) 0.950-0.975g / cm ３ A first ethylene homopolymer having a density of 5 to 70% by weight, ii) 0.950-0.975g / cm ３ A second ethylene homopolymer having a density of 95-30% by weight and Includes, Melt index I of the first ethylene homopolymer ２ Melt index I of the second ethylene homopolymer ２ The ratio is at least 10. The biaxially oriented polyethylene film structure according to claim 1.

5. The first polyethylene is 0.941–0.962 g / cm³ ３ A biaxially oriented polyethylene film structure according to claim 1, having the density of [a specific density].

6. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a melt index of 0.5 to 5.0 g / 10 min.

7. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a molecular weight distribution of 3.0 to 20.

0.

8. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a molecular weight distribution of 8.5 to 20.

0.

9. The biaxially oriented polyethylene film structure according to claim 1, wherein the first polyethylene has a Z-average molecular weight Mz of at least 500,000 g / mol.

10. The biaxially oriented polyethylene film structure according to claim 1, wherein the polyethylene homopolymer composition comprises 100 to 3,000 ppm (based on the weight of the polyethylene homopolymer composition) of a nucleating agent or a mixture of nucleating agents.

11. The biaxially oriented polyethylene film structure according to claim 1, wherein the nucleating agent or mixture of nucleating agents comprises a salt of a dicarboxylic acid.

12. Each of the three adjacent layers, i) 70-99.5% by weight of a first polyethylene, ii) 0.5 to 30% by weight of the second polyethylene and A biaxially oriented polyethylene film structure according to claim 1, comprising:

13. Each of the three adjacent layers, i) 90-99.5% by weight of a first polyethylene, ii) 0.5 to 10% by weight of a second polyethylene and A biaxially oriented polyethylene film structure according to claim 1, comprising:

14. A biaxially oriented polyethylene film structure according to claim 1, having a haze value of less than 15%.

15. A biaxially oriented polyethylene film structure according to claim 1, having a transparency value exceeding 80%.

16. 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 layers, the core layer, the first skin layer, and the second skin layer, i) 50 to 99.5% by weight of a first polyethylene, the first polyethylene being an ethylene copolymer having a density exceeding 0.940 g / cm ３ with a first polyethylene, and ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ ３ A polyethylene homopolymer composition having a density of a second polyethylene and Includes, A polyethylene homopolymer composition is a biaxially oriented polyethylene film structure comprising a nucleating agent or a mixture of nucleating agents.

17. The polyethylene homopolymer composition is 0.952 to 0.975 g / cm³. ３ A biaxially oriented polyethylene film structure according to claim 16, having the density of [value missing].

18. The biaxially oriented polyethylene film structure according to claim 16, wherein the polyethylene homopolymer composition has a melt index of 0.5 to 5 g / 10 min.

19. A polyethylene homopolymer composition i) 0.950-0.975g / cm ３ A first ethylene homopolymer having a density of 5 to 70% by weight, ii) 0.950-0.975g / cm ３ A second ethylene homopolymer having a density of 95-30% by weight and Includes, Melt index I of the first ethylene homopolymer ２ Melt index I of the second ethylene homopolymer ２ The ratio is at least 10. The biaxially oriented polyethylene film structure according to claim 16.

20. The first polyethylene is 0.941–0.962 g / cm³ ３ A biaxially oriented polyethylene film structure according to claim 16, having the density of [value missing].

21. The biaxially oriented polyethylene film structure according to claim 16, wherein the first polyethylene has a melt index of 0.5 to 5.0 g / 10 min.

22. The biaxially oriented polyethylene film structure according to claim 16, wherein the first polyethylene has a molecular weight distribution of 3.0 to 20.

0.

23. The biaxially oriented polyethylene film structure according to claim 16, wherein the first polyethylene has a molecular weight distribution of 8.5 to 20.

0.

24. The biaxially oriented polyethylene film structure according to claim 16, wherein the first polyethylene has a Z-average molecular weight Mz of at least 500,000 g / mol.

25. The biaxially oriented polyethylene film structure according to claim 16, wherein the polyethylene homopolymer composition comprises 100 to 3,000 ppm (based on the weight of the polyethylene homopolymer composition) of a nucleating agent or a mixture of nucleating agents.

26. The biaxially oriented polyethylene film structure according to claim 16, wherein the nucleating agent or mixture of nucleating agents comprises a salt of a dicarboxylic acid.

27. Each of the layers, the core layer, the first skin layer, and the second skin layer, i) 70-99.5% by weight of a first polyethylene, ii) 0.5 to 30% by weight of the second polyethylene and The biaxially oriented polyethylene film structure according to claim 16, including the above.

28. Each of the layers, the core layer, the first skin layer, and the second skin layer, i) 90-99.5% by weight of a first polyethylene, ii) 0.5 to 10% by weight of a second polyethylene and The biaxially oriented polyethylene film structure according to claim 16, including the above.

29. The biaxially oriented polyethylene film structure according to claim 16, having a haze value of less than 15%.

30. A biaxially oriented polyethylene film structure according to claim 16, having a transparency value exceeding 80%.

31. A biaxially oriented polyethylene film structure comprising at least three layers, The three adjacent layers are, i) 50-99.5% by weight of the first polyethylene, the first polyethylene being 0.940 g / cm³ ３ A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ ３ A second polyethylene is a high-density polyethylene having the density of Includes, High-density polyethylene contains a nucleating agent or a mixture of nucleating agents. The biaxially oriented polyethylene film structure has a haze value of less than 15%. Biaxially oriented polyethylene film structure.

32. 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 layers, the core layer, the first skin layer, and the second skin layer, i) 50-99.5% by weight of the first polyethylene, the first polyethylene being 0.940 g / cm³ ３ A first polyethylene is an ethylene copolymer having a density exceeding , ii) 0.5 to 50% by weight of the second polyethylene, the second polyethylene being at least 0.950 g / cm³ ３ A second polyethylene is a high-density polyethylene having the density of Includes, High-density polyethylene contains a nucleating agent or a mixture of nucleating agents. The biaxially oriented polyethylene film structure has a haze value of less than 15%. Biaxially oriented polyethylene film structure.

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