Highly rigid biaxially oriented polyethylene film

Abstract

A film having at least one layer, the layer comprising a multimodal high-density polyethylene having a melt index (I2) of 0.8 g / 10 min to 5.0 g / 10 min, a density of 0.950 g / cc to 0.965 g / cc, a polydispersity (Mw / Mn) of 10 to 20, and a molecular weight (Mz) of 500,000 g / mol to 1,000,000 g / mol. The film is a biaxially oriented polyethylene film.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of and priority to U.S. patent application Ser. No. 63 / 278,749, entitled "HIGH STIFFNESS BIAXIALLY ORIENTED POLYETHYLENE FILMS," filed on November 12, 2021, the entire contents of which are incorporated by reference into this disclosure.

[0002] FIELD OF THEINVENTION FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to biaxially oriented polyethylene (BOPE) films, and more particularly to BOPE films having high stiffness. [Background technology]

[0003] There is a market demand for the use of BOPE films in laminated flexible food packaging to facilitate packaging recycling. Although some commercially available BOPE films offer excellent optical properties and toughness, lack of stiffness and heat resistance limits the use of such BOPE films to a relatively narrow range of applications. The challenge in increasing stiffness in laminated BOPE flexible packaging is the level of high density polyethylene (HDPE) that can be incorporated into the film structure that allows for overall film density / stiffness while still maintaining a robust processing window.

[0004] Thus, there remains a need for BOPE multilayer films that are recyclable, have suitable stiffness and good processability. Summary of the Invention

[0005] Embodiments of BOPE films incorporating HDPE described herein meet these needs by providing BOPE films with improved stiffness and processability window.

[0006] In a first aspect, the present invention relates to a film comprising at least one layer, the at least one layer having a melt index (I ) between 0.8 g / 10 min and 5.0 g / 10 min. 2 ), a multimodal high density polyethylene having a density from 0.950 g / cc to 0.965 g / cc, a polydispersity (Mw / Mn) from 10 to 20, and a molecular weight (Mz) from 500,000 g / mol to 1,000,000 g / mol, and the film is a biaxially oriented polyethylene film.

[0007] In a second aspect, the present invention provides a multimodal high density polyethylene having a melt index (I ) of 1.0 g / 10 min to 3.0 g / 10 min. 2 The film of the first aspect comprises:

[0008] A third aspect includes the film of the first or second aspect, wherein the multimodal high density polyethylene has a density between 0.955 g / cc and 0.960 g / cc.

[0009] A fourth aspect includes the film according to any one of the first to third aspects, wherein the multimodal high density polyethylene comprises a polydispersity (Mw / Mn) that is 10-15.

[0010] A fifth aspect includes the film according to any one of the first to fourth aspects, wherein the multimodal high density polyethylene comprises a molecular weight Mz that is from 550,000 g / mol to 900,000 g / mol.

[0011] In a sixth aspect, the multimodal high density polyethylene has a melt index ratio (I 10 / I 2 The film according to any one of the first to fifth aspects includes the film according to the first to fifth aspects.

[0012] A seventh aspect includes the film according to any one of the first to sixth aspects, wherein the multimodal high density polyethylene comprises a molecular weight Mw that is from 110,000 g / mol to 135,000 g / mol.

[0013] An eighth aspect includes the film according to any one of the first to seventh aspects, wherein the multimodal high density polyethylene has a molecular weight Mn of 9,000 g / mol to 10,000 g / mol.

[0014] A ninth aspect is a multilayer film having a melt index (I 2 ), a core layer comprising a multimodal high density polyethylene having a density of 0.950 g / cc to 0.965 g / cc, a polydispersity (Mw / Mn) of 10 to 20, and a molecular weight (Mz) of 500,000 g / mol to 1,000,000 g / mol, a first layer positioned on a first side of the core layer, and a second layer positioned on a second side of the core layer.

[0015] In a tenth embodiment, at least one of the first layer and the second layer has a melt index (I 2 ) and a multimodal high density polyethylene having a density from 0.950 g / cc to 0.965 g / cc, a polydispersity (Mw / Mn) from 10 to 20, and a molecular weight (Mz) from 500,000 g / mol to 1,000,000 g / mol.

[0016] An eleventh embodiment comprises the multilayer film of the ninth or tenth embodiment, wherein the first layer and the second layer are made from the same material.

[0017] A twelfth aspect includes the multilayer film of any one of the ninth to eleventh aspects, wherein a first side of the first layer is positioned on a first side of the core layer, a first side of the second layer is positioned on a second side of the core layer, a third layer is positioned on a second side of the first layer, and a fourth layer is positioned on a second side of the second layer.

[0018] A thirteenth aspect includes the multilayer film according to any one of the ninth to twelfth aspects, wherein the multilayer film includes a haze of 2% to 70%.

[0019] A fourteenth aspect includes the multilayer film according to any one of the ninth to thirteenth aspects, wherein the multilayer film comprises a 1% secant modulus in MD (machine direction) of 500 MPa to 2500 MPa.

[0020] A fifteenth aspect includes a flexible package, a sachet, a pouch, or a stand-up pouch comprising the film according to any one of the first to eighth aspects or the multilayer film according to any one of the ninth to fourteenth aspects.

[0021] These and other embodiments are described in greater detail in the detailed description and figures that follow. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Specific embodiments of the present application will now be described. However, this disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present subject matter to those skilled in the art.

[0023] definition The term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether the monomers are the same or different. Thus, the generic term polymer encompasses the term "homopolymer," which is commonly used to refer to a polymer prepared from only one type of monomer, as well as "copolymer," which refers to a polymer prepared from two or more different monomers. As used herein, the term "interpolymer" refers to a polymer prepared by polymerization of at least two different types of monomers. Thus, the generic term interpolymer includes copolymers and polymers prepared from three or more different types of monomers, such as terpolymers.

[0024] "Polyethylene" or "ethylene-based polymer" shall mean a polymer containing more than 50 mole percent units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0025] The term "LDPE" may also be referred to as "high pressure ethylene polymer" or "highly branched polyethylene" and is defined to mean that the polymer is partially or fully homopolymerized or copolymerized in an autoclave or tubular reactor at pressures greater than 14,500 psi (100 MPa) with a free radical initiator such as a peroxide (see, for example, U.S. Pat. No. 4,599,392, incorporated herein by reference). LDPE resins typically have a density in the range of 0.916 to 0.935 g / cm.

[0026] The term "LLDPE" includes resins made using Ziegler-Natta catalyst systems, as well as resins made using single-site catalysts, including, but not limited to, bis-metallocene catalysts (sometimes referred to as "m-LLDPE") and constrained geometry catalysts, and resins made using post-metallocene, molecular catalysts. LLDPE includes linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains less long chain branching than LDPE and includes substantially linear ethylene polymers, as further defined in U.S. Patents 5,272,236, 5,278,272, 5,582,923, and 5,733,155; homogeneously branched linear ethylene polymer compositions, such as those in U.S. Patent 3,645,992, heterogeneously branched ethylene polymers, such as those prepared according to the process disclosed in U.S. Patent 4,076,698, and / or blends thereof, such as those disclosed in U.S. Patents 3,914,342 or 5,854,045. LLDPE resins may be made via gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0027] The term "MDPE" refers to polyethylene having a density of 0.926 to 0.945 g / cc. "MDPE" is typically prepared using chromium or Ziegler-Natta catalysts, or using single-site catalysts, including but not limited to bis-metallocene catalysts and constrained geometry catalysts.

[0028] The term "HDPE" generally refers to polyethylene having a density greater than about 0.945 g / cc up to about 0.980 g / cc prepared using single-site catalysts, including, but not limited to, Ziegler-Natta, chromium, or bis-metallocene and constrained geometry catalysts.

[0029] The term "ULDPE" generally refers to polyethylenes having a density of 0.880 to 0.909 g / cc prepared with Ziegler-Natta catalysts, single-site catalysts including, but not limited to, bis-metallocene catalysts and constrained geometry catalysts, and post-metallocene, molecular catalysts. As used herein, the term "propylene-based polymer" refers to a polymer that contains, in polymerized form, a polymer that contains greater than 50% by weight of units derived from propylene monomers. This includes propylene homopolymers, random copolymer polypropylenes, impact copolymer polypropylenes, propylene / α-olefin interpolymers, and propylene / α-olefin copolymers. These polypropylene materials are generally known in the art.

[0030] By "multilayer film" is meant any structure having two or more layers. For example, a multilayer structure may have 2, 3, 4, 5, or more layers. A multilayer film may be described as having layers designated by letters. For example, a three-layer structure having a core layer B and two outer layers A and C may be designated as A / B / C. Similarly, a structure having two core layers B and C and two outer layers A and D would be designated as A / B / C / D. Additionally, one skilled in the art would know that additional layers E, F, G, etc. may also be incorporated into this structure.

[0031] As used herein, "multimodal" refers to a composition that can be characterized as having at least two polymeric subcomponents with different densities and weight average molecular weights, and can optionally also have different melt index values. In one embodiment, multimodality can be defined by having at least two distinct peaks in a Gel Permeation Chromatography (GPC) chromatogram showing the molecular weight distribution. In another embodiment, multimodality can be defined by having at least two distinct peaks in a Crystallization Elution Fractionation (CEF) chromatogram showing the short chain branching distribution. Multimodality includes resins with two peaks, and resins with three or more peaks, for example, three or four peaks.

[0032] Reference will now be made in detail to the embodiments of the BOPE films of the present disclosure, which include a multimodal HDPE as disclosed and described herein. Some embodiments include multilayer films having at least one layer comprising a multimodal HDPE as disclosed and described herein.

[0033] The BOPE films disclosed and described herein have a melt index (I 2 ), and at least one layer comprising a multimodal HDPE having a density between 0.940 g / cc and 0.965 g / cc, a polydispersity (Mw / Mn) between 10 and 20, and a molecular weight (Mz) between 500,000 g / mol and 1,000,000 g / mol.

[0034] High Density Polyethylene In an embodiment, the multimodal HDPE has a viscosity of 0.8 g / 10 min to 5.0 g / 10 min, for example, 1.0 g / 10 min to 5.0 g / 10 min, 1.5 g / 10 min to 5.0 g / 10 min, 2.0 g / 10 min to 5.0 g / 10 min, 2.5 g / 10 min to 5.0 g / 10 min, 3.0 g / 10 min to 5.0 g / 10 min, 3.5 g / 10 min to 5.0 g / 10 min, 4.0 g / 10 min to 5.0 g / 10 min, 4.5 g / 10 min to 5.0 g / 10 min, 0.8 g / 10 min to 4.5 g / 10 min, 1.0 g / 10 min to 4 .5g / 10 minutes, 1.5g / 10 minutes ~ 4.5g / 10 minutes, 2.0g / 10 minutes ~ 4.5g / 10 minutes, 2.5g / 10 minutes ~ 4.5g / 10 minutes, 3.0g / 10 minutes ~ 4.5g / 10 minutes, 3.5g / 10 minutes ~ 4.5g / 10 minutes, 4.0g / 10 min~4.5g / 10min, 0.8g / 10min~4.0g / 10min, 1.0g / 10min~4.0g / 10min, 1.5g / 10min~4.0g / 10min, 2.0g / 10min~4.0g / 10min, 2.5g / 10min~4.0g / 10min, 3.0g / 10 minutes~4.0g / 10 minutes, 3.5g / 10 minutes~4.0g / 10 minutes, 0.8g / 10 minutes~3.5g / 10 minutes, 1.0g / 10 minutes~3.5g / 10 minutes, 1.5g / 10 minutes~3.5g / 10 minutes, 2.0g / 10 minutes~3.5g / 10 minutes, 2. 5g / 10min~3.5g / 10min, 3.0g / 10min~3.5g / 10min, 0.8g / 10min~3.0g / 10min, 1.0g / 10min~3.0g / 10min, 1.5g / 10min~3.0g / 10min, 2.0g / 10min~3.0g / 10min, Melt index (I) of 2.5g / 10min to 3.0g / 10min, 0.8g / 10min to 2.5g / 10min, 1.0g / 10min to 2.5g / 10min, 1.5g / 10min to 2.5g / 10min, 2.0g / 10min to 2.5g / 10min, 0.8g / 10min to 2.0g / 10min, 1.0g / 10min to 2.0g / 10min, 1.5g / 10min to 2.0g / 10min, 0.8g / 10min to 1.5g / 10min, 1.0g / 10min to 1.5g / 10min, or 0.8g / 10min to 1.0g / 10min 2 ).

[0035] In one or more embodiments, the multimodal HDPE may be from 0.950 g / cc to 0.965 g / cc, e.g., from 0.952 g / cc to 0.965 g / cc, from 0.955 g / cc to 0.965 g / cc, from 0.958 g / cc to 0.965 g / cc, from 0.960 g / cc to 0.965 g / cc, from 0.962 g / cc to 0.965 g / cc, from 0.950 g / cc to 0.962 g / cc, from 0.952 g / cc to 0.962 g / cc, from 0.955 g / cc to 0.962 g / cc, from 0.958 g / cc to 0.962 g / cc, from 0.962 g / cc to 0.965 g / cc, .960g / cc~0.962g / cc, 0.950g / cc~0.960g / cc, 0.952g / cc~0.960g / cc, 0.955g / cc~0.960g / cc, 0.958g / cc~0.960g / cc, 0.950g / cc~0.95 It has a density of 8g / cc, 0.952g / cc~0.958g / cc, 0.955g / cc~0.958g / cc, 0.950g / cc~0.955g / cc, 0.952g / cc~0.955g / cc, 0.950g / cc~0.952g / cc.

[0036] In an embodiment, the multimodal HDPE is 10 to 20, e.g., 11 to 20, 12 to 20, 13 to 20, 14 to 20, 15 to 20, 16 to 20, 17 to 20, 18 to 20, 19 to 20, 10 to 19, 11 to 19, 12 to 19, 13 to 19, 14 to 19, 15 to 19, 16 to 19, 17 to 19, 18 to 19, 10 to 18, 11 to 18, 12 to 18, 13 to 18, 14 to 18, 15 to 18, 16 to 18, 17 to 18, 10

[0043] The polydispersity (Mw / Mn) of the copolymer is 10-14, 11-14, 12-14, 13-14, 10-13, 11-13, 12-13, 10-12, 11-12, or 10-11.

[0037] In an embodiment, the multimodal HDPE is 5.0 to 15.0, for example, 6.0 to 15.0, 7.0 to 15.0, 8.0 to 15.0, 9.0 to 15.0, 10.0 to 15.0, 11.0 to 15.0, 12.0 to 15.0, 13.0 to 15.0, 14.0 to 15.0, 5.0 to 14.0, 6.0 to 14.0, 7.0~14.0, 8.0~14.0, 9.0~14.0, 10.0~14.0, 11.0~14.0, 12.0~14.0, 13.0~14.0, 5.0~13.0, 6.0~13.0, 7.0~13.0, 8.0~13.0, 9.0~13.0, 10.0~13.0, 11.0~13.0, 12 .0~13.0, 5.0~12.0, 6.0~12.0, 7.0~12.0, 8.0~12.0, 9.0~12.0, 10.0~12.0, 11.0~12.0, 5.0~11.0, 6.0~11.0, 7.0~11.0, 8.0~11.0, 9.0~11.0, 10.0~11.0, 5.0~1 Melt index ratios (I 10 / I 2 ).

[0038] In one or more embodiments, the multimodal HDPE has a melt index ratio (I) of 60 to 80, e.g., 62 to 80, 65 to 80, 68 to 80, 70 to 80, 72 to 80, 75 to 80 78 to 80, 60 to 78, 62 to 78, 65 to 78, 68 to 78, 70 to 78, 72 to 78, 75 to 78, 60 to 75, 62 to 75, 65 to 75, 68 to 75, 70 to 75, 72 to 75, 60 to 72, 62 to 72, 65 to 72, 68 to 72, 70 to 72, 60 to 70, 62 to 70, 65 to 70, 68 to 70, 60 to 68, 62 to 68, 65 to 68, 60 to 65, 62 to 65, or 60 to 62. 21 / I 2 ).

[0039] In the embodiment, the multimodal HDPE has a molecular weight of 9,000 g / mol to 10,000 g / mol, for example, 9,100 g / mol to 10,000 g / mol, 9,200 g / mol to 10,000 g / mol, 9,300 g / mol to 10,000 g / mol, 9,400 g / mol to 10,000 g / mol, 9,500 g / mol to 10,000 g / mol, 9,600 g / mol to 10,000 g / mol, 9,700 g / mol to 10,000 g / mol, 9,800 g / mol to 10,000 g / mol, 9,900 g / mol to 10,000 g / mol, 9,000 g / mol to 9,900 g / mol, 9,100 g / mol to 9,900 g / mol, 9,200 g / mol to 9,900 g / mol, 9,300 g / mol to 9,900 g / mol, 9,400 g / mol to 9,900 g / mol, 9,500 g / mol to 9,900 g / mol, 9,600 g / mol to 9,900 g / mol, 9,700 g / mol to 9,900 g / mol, 9,800 g / mol to 9,900 g / mol, 9,000 g / mol to 9,800 g / mol, 9,100 g / mol to 9,800 g / mol, 9,200 g / mol to 9,800 g / mol, 9,300 g / mol to 9,800 g / mol, 9,400 g / mol to 9,800 g / mol, 9,500 g / mol to 9,800 g / mol, 9,600 g / mol to 9,800 g / mol, 9,700 g / mol to 9,800 g / mol, 9,000 g / mol to 9,700 g / mol, 9,100 g / mol to 9,700 g / mol, 9,200 g / mol to 9,700 g / mol, 9,300 g / mol to 9,700 g / mol, 9,400 g / mol to 9,700 g / mol, 9,500 g / mol to 9,700 g / mol, 9,600 g / mol to 9,700 g / mol, 9,000 g / mol to 9,600 g / mol, 9,100 g / mol to 9,600 g / mol, 9,200 g / mol to 9,600 g / mol, 9,300 g / mol to 9,600 g / mol, 9,400 g / mol to 9,600 g / mol, 9,500 g / mol to 9,600 g / mol, 9,000 g / mol to 9,500 g / mol, 9,100 g / mol to 9,500 g / mol, 9,200 g / mol to 9,500 g / mol, 9,300 g / mol to 9,500 g / mol, 9,The molecular weight (Mn) measured by GPC is 400g / mol to 9,500g / mol, 9,000g / mol to 9,400g / mol, 9,100g / mol to 9,400g / mol, 9,200g / mol to 9,400g / mol, 9,300g / mol to 9,400g / mol, 9,000g / mol to 9,300g / mol, 9,100g / mol to 9,300g / mol, 9,200g / mol to 9,300g / mol, 9,000g / mol to 9,200g / mol, 9,100g / mol to 9,200g / mol, or 9,000g / mol to 9,100g / mol.

[0040] In one or more embodiments, the multimodal HDPE has a weight average molecular weight of from 110,000 g / mol to 135,000 g / mol, such as from 112,000 g / mol to 135,000 g / mol, from 115,000 g / mol to 135,000 g / mol, from 118,000 g / mol to 135,000 g / mol, from 120,000 g / mol to 135,000 g / mol, from 122,000 g / mol to 135,000 g / mol, from 125,000 g / mol to 135,000 g / mol, from 128,000 g / mol to 135,000 g / mol, from 130,000 g / mol to 135,000 g / mol, from 132,000 g / mol to 135,000 g / mol, from 110,000 g / mol to 132,000 g / mol, from 112,000 g / mol to 132,000 g / mol, from 115,000 g / mol to 132,000 g / mol, from 118,000 g / mol to 132,000 g / mol, from 120,000 g / mol to 132,000 g / mol, from 122,000 g / mol to 132,000 g / mol, from 125,000 g / mol to 132,000 g / mol, from 128,000 g / mol to 132,000 g / mol, from 130,000 g / mol to 132,000 g / mol, from 110,000 g / mol to 130,000 g / mol, from 112,000 g / mol to 130,000 g / mol, from 115,000 g / mol to 130,000 g / mol, from 118,000 g / mol to 130,000 g / mol, from 120,000 g / mol to 130,000 g / mol, from 122,000 g / mol to 130,000 g / mol, from 125,000 g / mol to 130,000 g / mol, from 128,000 g / mol to 130,000 g / mol, from 110,000 g / mol to 128,000 g / mol, from 112,000 g / mol to 128,000 g / mol, from 115,000 g / mol to 128,000 g / mol, from 118,000 g / mol to 128,000 g / mol, from 120,000 g / mol to 128,000 g / mol, from 122,000 g / mol to 128,000 g / mol, from 125,000 g / mol to 128,000 g / mol, from 110,000 g / mol to 125,000 g / mol, from 112,000 g / mol to 125,000 g / mol, from 115,000 g / mol to 125,000 g / mol, from 118,000g / mol~125,000g / mol, 120,000g / mol~125,000g / mol, 122,000g / mol~125,000g / mol, 110,000g / mol~122,000g / mol, 112,000g / mol~122,000g / mol, 115,000g / mol~122,000g / mol, 118,000g / mol~122,000g / mol, 120,000g / mol~122,000g / mol, 110,000g / mol~120,000g / mol, 112,000g / mol~12 The molecular weight (Mw) measured by GPC is 0,000 g / mol, 115,000 g / mol to 120,000 g / mol, 118,000 g / mol to 120,000 g / mol, 110,000 g / mol to 118,000 g / mol, 112,000 g / mol to 118,000 g / mol, 115,000 g / mol to 118,000 g / mol, 110,000 g / mol to 115,000 g / mol, 112,000 g / mol to 115,000 g / mol, or 110,000 g / mol to 112,000 g / mol.

[0041] In one or more embodiments, the multimodal HDPE has a molecular weight of 600,000 g / mol to 1,300,000 g / mol, for example, 650,000 g / mol to 1,300,000 g / mol, 700,000 g / mol to 1,300,000 g / mol, 750,000 g / mol to 1,300,000 g / mol, 800,000 g / mol to 1,300,000 g / mol, 850,000 g / mol to 1,300,000 g / mol, 900,000 g / mol to 1,300,000 g / mol, 950,000 g / mol to 1,300,000 g / mol, 1,000,000 g / mol to 1,300,000 g / mol, 1,050,000 g / mol to 1,300,000 g / mol, 1,100,000 g / mol to 1,300,000 g / mol, 1,150,000 g / mol to 1,300,000 g / mol, 1,200,000 g / mol to 1,300,000 g / mol, 1,250,000 g / mol to 1,300,000 g / mol, 600,000 g / mol to 1,250,000 g / mol, 650,000 g / mol to 1,250,000 g / mol, 700,000 g / mol to 1,250,000 g / mol, 750,000 g / mol to 1,250,000 g / mol, 800,000 g / mol to 1,250,000 g / mol, 850,000 g / mol to 1,250,000 g / mol, 900,000 g / mol to 1,250,000 g / mol, 950,000 g / mol to 1,250,000 g / mol, 1,000,000 g / mol to 1,250,000 g / mol, 1,050,000 g / mol to 1,250,000 g / mol, 1,100,000 g / mol to 1,250,000 g / mol, 1,150,000 g / mol to 1,250,000 g / mol, 1,200,000 g / mol to 1,250,000 g / mol, 600,000 g / mol to 1,200,000 g / mol, 650,000 g / mol to 1,200,000 g / mol, 700,000 g / mol to 1,200,000 g / mol, 750,000 g / mol to 1,200,000 g / mol, 800,000 g / mol to 1,200,000 g / mol, 850,000 g / mol to 1,200,000 g / mol, 900,000 g / mol to 1,200,000g / mol、950,000g / mol~1,200,000g / mol、1,000,000g / mol~1,200,000g / mol、1,050,000g / mol~1,200,000g / mol、1,100,000g / mol~1,200,000g / mol、1,150,000g / mol~1,200,000g / mol、600,000g / mol~1,100,000g / mol、650,000g / mol~1,100,000g / mol、700,000g / mol~1,100,000g / mol、750,000g / mol~1,100,000g / mol、800,000g / mol~1,100,000g / mol、850,000g / mol~1,100,000g / mol、900,000g / mol~1,100,000g / mol、950,000g / mol~1,100,000g / mol、1,000,000g / mol~1,100,000g / mol、1,050,000g / mol~1,100,000g / mol、600,000g / mol~1,050,000g / mol、650,000g / mol~1,050,000g / mol、700 ,000g / mol~1,050,000g / mol、750,000g / mol~1,050,000g / mol、800,000g / mol~1,050,000g / mol、850,000g / mol~1,050,000g / mol、900,000g / mol~1,050,000g / mol、950,000g / mol~1,050,000g / mol、1,000,000g / mol~1,050,000g / mol、600,000g / mol~1,000,000g / mol、650,000g / mol~1,000,000g / mol ,700,000g / mol~1,000,000g / mol, 750,000g / mol~1,000,000g / mol, 800,000g / mol~1,000,000g / mol, 850,000g / mol~1,000,000g / mol, 900,000g / mol~1,000,000g / mol, 950,000g / mol~1,000,000g / mol, 600,000g / mol~950,000g / mol, 650,000g / mol~950,000g / mol, 700,000g / mol~950,000g / mol, 750,000g / mol~950,000g / mol, 800,000g / mol~950,000g / mol, 850,000g / mol~950,000g / mol, 900,000g / m ol~950,000g / mol, 600,000g / mol~900,000g / mol, 650,000g / mol~900,000g / mol, 700,000g / mol~900 ,000g / mol, 750,000g / mol~900,000g / mol, 800,000g / mol~900,000g / mol, 850,000g / mol~900,000g / mol, 600,000g / mol~850,000g / mol, 650,000g / mol~850,000g / mol, 700,000g / mol~850,000g / mol, 750 ,000g / mol~850,000g / mol, 800,000g / mol~850,000g / mol, 600,000g / mol~800,000g / mol, 650,000g / mol mol~800,000g / mol, 700,000g / mol~800,000g / mol, 750,000g / mol~800,000g / mol, 600,000g / mol~75 The molecular weight (Mz) measured by GPC is 0,000 g / mol, 650,000 g / mol to 750,000 g / mol, 700,000 g / mol to 750,000 g / mol, 600,000 g / mol to 700,000 g / mol, 650,000 g / mol to 700,000 g / mol, or 600,000 g / mol to 650,000 g / mol.

[0042] In one or more embodiments, the multimodal HDPE may be 5.0-10.0, e.g., 5.5-10.0, 6.0-10.0, 6.5-10.0, 7.0-10.0, 7.5-10.0, 8.0-10.0, 8.5-10.0, 9.0-10.0, 9.5-10.0, 5.0-9.5, 5.5-9.5, 6.0-9.5, 6.5-9.5, 7.0-9.5, 7.5-9.5, 8.0-9.5, 8.5-9.5, 9.0-9.5, 5.0-9.0, 5.5-9.0, 6.0-9.0, 6.5-9.0, 7.0-9.0, 7.5-9.0, 8.0-9.0, 8.5- The molecular weight ratio (Mz / Mw) is 9.0, 5.0-8.5, 5.5-8.5, 6.0-8.5, 6.5-8.5, 7.0-8.5, 7.5-8.5, 8.0-8.5, 5.0-8.0, 5.5-8.0, 6.0-8.0, 6.5-8.0, 7.0-8.0, 7.5-8.0, 5.0-7.5, 5.5-7.5, 6.0-7.5, 6.5-7.5, 7.0-7.5, 5.0-7.0, 5.5-7.0, 6.0-7.0, 6.5-7.0, 5.0-6.5, 5.5-6.5, 6.0-6.5, 5.0-6.0, 5.5-6.0, or 5.0-5.5.

[0043] In embodiments, the multimodal HDPE disclosed and described herein can be made by any suitable process. In one or more embodiments, the multimodal HDPE disclosed and described herein can be made by gas phase polymerization, slurry polymerization, or a combination of gas phase polymerization and slurry polymerization. In embodiments, the multimodal HDPE disclosed and described herein can be made by gas phase polymerization. For example, the multimodal HDPE disclosed and described herein can be made by the method disclosed in U.S. Patent No. 8,455,594, the entirety of which is incorporated herein by reference.

[0044] In one or more embodiments, the HDPE disclosed or described herein may be made using a dual sequential polymerization system, e.g., a first gas phase reactor and a second gas phase reactor operating in series. The polymerization system comprises ethylene, one or more α-olefin comonomers, hydrogen, a catalyst, e.g., a Ziegler-Natta catalyst slurried in mineral oil, N2 , and isopentane may be continuously fed to the first reactor. A cocatalyst, such as triethylaluminum (TEAL), may then be fed to the first reactor to activate the catalyst. A first polymerization reaction of ethylene in the presence of 1-hexene is then carried out in the first reactor under the conditions shown in Table 1 below, thereby producing a first component-catalyst complex. The first component-catalyst complex is transferred to a second reactor. Additional ethylene, hydrogen, a cocatalyst, such as TEAL, N 2 , and isopentane may be fed to the second reactor. In an embodiment, no additional catalyst is added to the second reactor. A second polymerization reaction of ethylene may be carried out in the second reactor under the conditions shown in Table 1 below, thereby producing a first component-catalyst-second component complex. The first component-catalyst-second component complex may be removed in batches from the second reactor into a product chamber, purged to remove residual hydrocarbons, and then transferred to a drum. The drum may be purged with humidified nitrogen.

[0045] [Table 1]

[0046] Films and multi-layer films Multimodal HDPE, with the above combination of properties, exhibits excellent processability and tunable performance in films according to some embodiments. The stretch performance of the multimodal HDPE is typically more stable than other conventional HDPEs and slightly better than other resins. The multimodal HDPE can be implemented in some embodiments at 50% to 100% in the core layer without any problems. The multimodal HDPE also requires less torque to extrude at the same rpm / output than other conventional HDPE resins in some embodiments. This is a very important feature since many of the existing biaxially oriented polypropylene (BOPP) orientation lines were designed to extrude polypropylene using lower torque than most polyethylene can handle. Thus, when running a BOPP orientation line with polyethylene, the line typically suffers a significant drop in output, sometimes 60% to 70%. Furthermore, upgrading an extruder system to accommodate polyethylene can be very costly. Thus, HDPE, which can be run at 100% without reducing production rates, can provide a significantly more attractive and recyclable alternative to polypropylene.

[0047] Commercially available HDPEs have been evaluated, and some of them have sufficient stretchability, but most of them have stretchability between 0.4g / 10min and 0.9g / 10min I 2 In some embodiments of the present invention, the HDPE used has a higher MI (MI) in the range of 1.5 g / 10 min. 2 ) and high Mz. Without wishing to be bound by any particular theory, it is believed that the increased MI (I 2It is believed that the combination of high Mz and relatively low density provides the robust orientation performance seen in the HDPE disclosed and described herein for use in some embodiments of this invention. The relatively low density is also believed to be a key factor in slowing down the crystallization rate and thus making the web more stable and easier to stretch in both the MDO and TDO stages.

[0048] In an embodiment, the biaxially oriented polyethylene film is a monolayer film comprising the above-mentioned HDPE as the only layer.

[0049] When the film is a monolayer film, the layer may contain one or more additives, as is generally known. Such additives include antioxidants, such as IRGANOX 1010 and IRGAFOS 168 (available from BASF), UV absorbers, antistatic agents, pigments, dyes, nucleating agents, fillers, slip agents, flame retardants, plasticizers, processing aids, lubricants, stabilizers, smoke suppressants, viscosity control agents, surface modifiers, and antiblocking agents. In some embodiments, the layer composition may contain, for example, less than 10 total weight percent, and in other embodiments, less than 5 weight percent, of one or more additives, based on the weight of the layer. In embodiments, the layers in the multilayer film may be blends of HDPE as described herein with one or more of LLDPE, LDPE, ethylene-propylene copolymers, polyethylene plastomers, and the like.

[0050] In embodiments where the film is a monolayer film comprising HDPE as disclosed herein, the film layer, according to embodiments, comprises at least 40% by weight of the HDPE disclosed herein, e.g., at least 45% by weight of the HDPE disclosed herein, at least 50% by weight of the HDPE disclosed herein, at least 55% by weight of the HDPE disclosed herein, at least 60% by weight of the HDPE disclosed herein, at least 65% by weight of the HDPE disclosed herein, at least 70% by weight of the HDPE disclosed herein, at least 75% by weight of the HDPE disclosed herein, at least 80% by weight of the HDPE disclosed herein, at least 90% by weight of the HDPE disclosed herein, or at least 95% by weight of the HDPE disclosed herein. In embodiments where the film is a monolayer film comprising HDPE as disclosed herein, the film layer, in embodiments, consists or consists essentially of the HDPE disclosed herein.

[0051] In some embodiments, the biaxially oriented polyethylene film is a multilayer film in which at least one layer comprises the HDPE disclosed herein. For example, the multilayer film can include a layer comprising the HDPE disclosed herein and further includes other layers typically included in multilayer films depending on the application including, for example, sealant layers, barrier layers, tie layers, other polyethylene layers, polypropylene layers, etc. In embodiments in which the film is a multilayer film, the layer comprising the HDPE disclosed and described herein is the core layer of the multilayer film.

[0052] As an example, in some embodiments, a multilayer film can include the aforementioned layer (B layer) comprising the HDPE disclosed herein, and another layer (A layer), wherein the A layer includes an upper surface and a lower surface, and the upper surface of the A layer is in adhesive contact with the lower surface of the B layer.

[0053] In some such embodiments, the A layer may be a sealant layer formed from one or more ethylene-based polymers known to those of skill in the art to be suitable for use in sealant layers.

[0054] However, as mentioned above, the A layer can include any number of other polymers or polymer blends. For example, if the multilayer film includes a barrier layer, the A layer can be a tie layer in adhesive contact between the outer layer and the barrier layer, and another tie layer can be between the barrier layer and the sealant layer. It should also be understood that the multilayer film of the embodiment can include two A layers, one on each major surface of the B layer, the major surfaces representing the surfaces with the large surface area, and the film has two major surfaces that are opposite and parallel to each other. Thus, in an embodiment, the multilayer film is a three-layer BOPE film, which can be described as an A / B / A film. It should be understood that in an embodiment, each A layer can have the same composition, and in other embodiments, the two A layers can have different compositions.

[0055] In an embodiment, the multilayer film may be a 5-layer BOPE film having a B layer (such as a core layer) made from HDPE as disclosed and described herein. On a major surface of the B layer is a first tie layer (D layer) and a second tie layer (also D layer) on a second major surface of the B layer. The first tie layer has a skin layer (A layer) on its opposite major surface from the B layer, and the second tie layer has a skin layer (C layer) on its opposite major surface from the B layer. The 5-layer film may be described as an A / D / B / D / C film.

[0056] In one or more embodiments, the tie layer D layer is the same material. In some embodiments, the tie layer D layer is made of the same material as the B layer. Thus, in one or more embodiments, the B layer and the tie layer D layer are all made of or include the multimodal HDPE disclosed and described herein. However, in other embodiments, the tie layer D layer is not made of the same material as the B layer. In embodiments, the D layer includes a blend of LLDPE and HDPE (either the HDPE disclosed and described herein or another HDPE), or the D layer may be a tie resin (e.g., an ethylene-propylene copolymer or a maleic anhydride modified polymer).

[0057] In an embodiment, the skin layers A and C may be made of the same material. In other embodiments, the skin layers A and C may be made of different materials. In one embodiment, both skin layers A and C are made of BOPE, such as INNATE manufactured by the Dow Chemical Company. In an embodiment, the A and C layers comprise one or more of LLDPE, a blend of LLDPE and HDPE (either the HDPEs disclosed and described herein or another HDPE), HDPE (either the HDPEs disclosed and described herein or another HDPE), polypropylene, ethylene-propylene copolymer, or polyimide.

[0058] It should be understood that any of the foregoing layers may further include one or more additives known to those skilled in the art, such as, for example, antioxidants, UV stabilizers, heat stabilizers, lubricants, antiblocking agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, and blowing agents.

[0059] In embodiments where the film is a multilayer film, at least one layer of the multilayer film comprises HDPE as disclosed herein. At least one layer comprising HDPE as disclosed herein comprises, according to embodiments, at least 40% by weight of HDPE as disclosed herein, e.g., at least 45% by weight of HDPE as disclosed herein, at least 50% by weight of HDPE as disclosed herein, at least 55% by weight of HDPE as disclosed herein, at least 60% by weight of HDPE as disclosed herein, at least 65% by weight of HDPE as disclosed herein, at least 70% by weight of HDPE as disclosed herein, at least 75% by weight of HDPE as disclosed herein, at least 80% by weight of HDPE as disclosed herein, at least 90% by weight of HDPE as disclosed herein, or at least 95% by weight of HDPE as disclosed herein. In embodiments, at least one film layer comprising HDPE as disclosed herein consists or essentially consists of HDPE as disclosed herein.

[0060] Multilayer films may be formed and oriented (e.g., biaxially oriented) by any suitable process. Information about these processes can be found in references such as, for example, the Kirk Othmer Encyclopedia, the Modern Plastics Encyclopedia, or the Wiley Encyclopedia of Packaging Technology, 2d edition, A.L. Brody and K.S. Marsh, Eds., Wiley-Interscience (Hoboken, 1997). For example, multilayer films may be formed by sheet casting or any other suitable casting procedure. Suitable orientation processes include tenter frame techniques. When the film is a multilayer film, the various film layers may be coextruded by any suitable means.

[0061] Such polyethylene films (whether monolayer or multilayer) may have a variety of thicknesses prior to biaxial orientation, depending, for example, on the number of layers, the intended use of the film, and other factors. Such polyethylene films, in some embodiments, have a thickness of 0.8 to 1.0 mm prior to biaxial orientation.

[0062] In some embodiments, the polyethylene film is biaxially oriented using a tenter frame sequential biaxial orientation process. Such techniques are generally known to those skilled in the art. Generally, in a tenter frame sequential biaxial orientation process, a tenter frame is incorporated as part of a multilayer coextrusion line. After extrusion from a flat die, the film is cooled on a chill roll and immersed in a water bath filled with room temperature water. The cast film is then passed over a series of rollers with different rotation speeds to achieve stretching in the machine direction. There are several pairs of rollers in the MD stretching segment of the production line, all of which are oil heated. The pairs of rollers operate sequentially as preheat rollers, stretch rollers, and relaxation and annealing rollers. The temperature of each pair of rollers is controlled separately. After stretching in the machine direction, the film web is passed through a tenter frame hot air oven with heating zones to perform stretching in the transverse direction. The first several zones are for preheating, followed by a zone for stretching, and then a final zone for annealing.

[0063] The uniaxially oriented film can be introduced into a tenter frame at a line speed of about 20-28 meters per minute, preheated at about 140°C-155°C, stretched in the transverse direction at about 120°C-130°C with a stretch ratio of about 6-8 times the original width, and then heat set or annealed at about 105°C-120°C to reduce the internal stresses due to orientation, minimize heat shrinkage in the final film, and result in a relatively heat stable biaxially oriented film.

[0064] In an embodiment, the film may have a viscosity of 4.5:1 to 6.5:1, e.g., 4.8:1 to 6.5:1, 5.0:1 to 6.5:1, 5.2:1 to 6.5:1, 5.5:1 to 6.5:1, 5.8:1 to 6.5:1, 6.0:1 to 6.5:1, 6.2:1 to 6.5:1, 4.5:1 to 6.2:1, 4.8:1 to 6.2:1, 5.0:1 to 6.2:1, 5.2:1 to 6.2:1, 5.5:1 to 6.2:1, 5.8:1 to 6.2:1, 6.0:1 to 6.2:1, 4.5:1 to 6.0:1, 4.8:1 to 6.0:1, 5.0:1 to 6.0:1, 5. The film may be stretched at a machine direction stretch ratio of 2:1 to 6.0:1, 5.5:1 to 6.0:1, 5.8:1 to 6.0:1, 4.5:1 to 5.8:1, 4.8:1 to 5.8:1, 5.0:1 to 5.8:1, 5.2:1 to 5.8:1, 5.5:1 to 5.8:1, 4.5:1 to 5.5:1, 4.8:1 to 5.5:1, 5.0:1 to 5.5:1, 5.2:1 to 5.5:1, 4.5:1 to 5.2:1, 4.8:1 to 5.2:1, 5.0:1 to 5.2:1, 4.5:1 to 5.0:1, 4.8:1 to 5.0:1, 4.5:1 to 4.8:1.

[0065] In an embodiment, the film may have a viscosity of 6.0:1 to 9.0:1, e.g., 6.2:1 to 9.0:1, 6.5:1 to 9.0:1, 6.8:1 to 9.0:1, 7.0:1 to 9.0:1, 7.2:1 to 9.0:1, 7.5:1 to 9.0:1, 7.8:1 to 9.0:1, 8.0:1 to 9.0:1, 8.2:1 to 9.0:1, 8.5:1 to 9.0:1, 8.8:1 to 9.0:1, 6.0:1 to 8.8:1, 6.2:1 to 8.8:1, 6.5:1 to 8.8:1, 6.8:1 to 8.8:1, 7.0:1 to 8.8:1, 7.2:1 to 8.8:1, 7.5:1 to 8.8: 1, 7.8:1~8.8:1, 8.0:1~8.8:1, 8.2:1~8.8:1, 8.5:1~8.8:1, 6.0:1~8.5:1, 6.2:1~8.5:1, 6.5:1~8.5:1, 6.8:1~8.5:1, 7.0:1~8.5:1, 7.2:1~8.5:1, 7.5:1~8.5:1, 7.8:1~8.5:1, 8.0:1~8.5:1, 8.2:1~8.5:1, 6.0:1~8.2:1, 6.2:1~8.2:1, 6.5:1~8.2:1, 6.8:1~8.2:1, 7.0:1~8.2:1, 7.2:1~8.2:1, 7. 5:1~8.2:1, 7.8:1~8.2:1, 8.0:1~8.2:1, 6.0:1~8.0:1, 6.2:1~8.0:1, 6.5:1~8.0:1, 6.8:1~8.0:1, 7.0:1~8.0:1, 7.2:1~8.0:1, 7.5:1~8.0:1, 7.8:1~8.0:1, 6.0:1~7.8:1, 6.2:1~7.8:1, 6.5:1~7.8:1, 6.8:1~7.8:1, 7.0:1~7.8:1, 7.2:1~7.8:1, 7.5:1~7.8:1, 6.0:1~7.5:1, 6.2:1~7.5:1, 6.5:1~ The film may be stretched at a stretch ratio in the transverse direction of 7.5:1, 6.8:1 to 7.5:1, 7.0:1 to 7.5:1, 7.2:1 to 7.5:1, 6.0:1 to 7.2:1, 6.2:1 to 7.2:1, 6.5:1 to 7.2:1, 6.8:1 to 7.2:1, 7.0:1 to 7.2:1, 6.0:1 to 7.0:1, 6.2:1 to 7.0:1, 6.5:1 to 7.0:1, 6.8:1 to 7.0:1, 6.0:1 to 6.8:1, 6.2:1 to 6.8:1, 6.5:1 to 6.8:1, 6.0:1 to 6.5:1, 6.2:1 to 6.5:1, or 6.0:1 to 6.2:1.

[0066] In some embodiments, after orientation, the biaxially oriented film has a thickness of 10 to 60 micrometers, hi some embodiments, the biaxially oriented film has a thickness of 10 to 30 micrometers.

[0067] In some embodiments, for example, depending on the end use application, the biaxially oriented polyethylene film can be corona treated, plasma treated, or printed using techniques known to those of skill in the art.

[0068] Multilayer film properties In an embodiment, a multilayer film comprising a layer comprising a multimodal HDPE as disclosed and described herein in at least a core layer may comprise from 2% to 70%, e.g., from 5% to 70%, from 10% to 70%, from 15% to 70%, from 20% to 70%, from 25% to 70%, from 30% to 70%, from 35% to 70%, from 40% to 70%, from 45% to 70%, from 50% to 70%, from 55% to 70%, from 60% to 70%, from 65% to 70%, from 2% to 65%, from 5% to 65%, from 10% to 65%, from 15% to 65%, from 20% to 65%, from 25% to 65%, from 30% to 65%, from 35% to 65%, from 40% to 65%, from 45% to 65%, 50%~65%, 55%~65%, 60%~65%, 2%~60%, 5%~60%, 10%~60%, 15%~60%, 20%~60%, 25%~60%, 30%~60%, 35%~60%, 40%~60%, 45%~60%, 50%~60%, 55%~60%, 2%~60 %, 5%~60%, 10%~60%, 15%~60%, 20%~60%, 25%~60%, 30%~60%, 35%~60%, 40%~60%, 45%~60%, 50%~60%, 55%~60%, 2%~55%, 5%~55%, 10%~55%, 15%~55%, 20%~5 5%, 25%~55%, 30%~55%, 35%~55%, 40%~55%, 45%~55%, 50%~55%, 2%~50%, 5%~50%, 10%~50%, 15%~50%, 20%~50%, 25%~50%, 30%~50%, 35%~50%, 40%~50%, 45 %~50%, 2%~45%, 5%~45%, 10%~45%, 15%~45%, 20%~45%, 25%~45%, 30%~45%, 35%~45%, 40%~45%, 2%~40%, 5%~40%, 10%~40%, 15%~40%, 20%~40%, 25%~40%, 30 %~40%, 35%~40%, 2%~35%, 5%~35%, 10%~35%, 15%~35%, 20%~35%, 25%~35%, 30%~35%, 2%~30%, 5%~30%, 10%~30%, 15%~30%, 20%~30%, 25%~30%, 2%~25%, 5%~ 25%, 10%~25%, 15%~25%, 20%~25%, 2%~20%, 5%~20%, 10%~20%, 15%~20%, 2%~20%, 5%~20%, 10%~20%, 15%~20%, 2%~15%, 5%~15%, 10%~15%, 2%~10%, 5%~10%,Or has a haze of 2% to 5%.

[0069] In one or more embodiments, the multilayer film comprising the multimodal HDPE disclosed and described herein in at least the core layer has a modulus of 500 MPa to 2500 MPa, e.g., 750 MPa to 2500 MPa, 1000 MPa to 2500 MPa, 1250 MPa to 2500 MPa, 1500 MPa to 2500 MPa, 1750 MPa to 2500 MPa, 2000 MPa to 2500 MPa, 2250 MPa to 2500 MPa, 500 MPa to 2250 MPa, 750 MPa to 2250 MPa, 1000 MPa to 2250 MPa, 1250 MPa to 2250 MPa, 1500 MPa to 2250 MPa, 1750 MPa to 2250 MPa, 2000 MPa to 2250 MPa, 500 MPa to 2000 MPa, 750 MPa to 2000 MPa a, 1000MPa to 2000MPa, 1250MPa to 2000MPa, 1500MPa to 2000MPa, 1750MPa to 2000MPa, 500MPa to 1750MPa, 750MPa to 1750MPa, 1000MPa to 1750MPa, 1250MPa to 1750MPa, 1500MPa to 1750MPa, 500MPa to 1500MPa, 750MPa to 1500MPa, 1000MPa to 1500MPa, 1250MPa to 1500MPa, 500MPa to 1250MPa, 750MPa to 1250MPa, 1000MPa to 1250MPa, 500MPa to 1000MPa, 750MPa to 1000MPa, or 500MPa to 750MPa.

[0070] Goods In various embodiments, the multilayer films disclosed herein can be used to form articles such as packaging. Such articles can be formed from any of the multilayer films described herein. Examples of packaging that can be formed from the multilayer films of various embodiments include flexible packaging, sachets, pouches, stand-alone pouches, and pre-made packages or pouches. In some embodiments, the multilayer films described herein can be used in food packaging, such as packaging for meat, cheese, cereal, nuts, juice, sauce, chips, snacks, and the like. Such packaging can be formed using techniques known to those skilled in the art based on the teachings herein and based on the particular application of the packaging (e.g., type of food, amount of food, etc.).

[0071] Test Method The test methods include the following:

[0072] Hayes Haze was measured according to ASTM D1003. Hazegard Plus (BYK-Gardner USA, Columbia, MD) is used for the test. Overall haze is reported as the average of five measurements.

[0073] density Compression molded samples for density measurement were prepared according to ASTM D 4703. Density measurements were performed within 2 hours of molding according to ASTM D792, Method B.

[0074] Melt Index Melt Index (I 2 ) was measured according to ASTM D-1238 at 190°C and a load of 2.16 kg. 2 Values ​​are reported in units of dg / min.

[0075] Secant Elastic Modulus The secant modulus was measured based on a tensile test according to ASTM D882. The film is conditioned at 23°C (+ / -2°C) and 50% R.H + / -10% for at least 40 hours after film production according to ASTM standards. Standard test conditions are 23°C (+ / -2°C) and 50% RH (+ / -10%) according to ASTM standards. Tensile test strips are cut from the film in the machine and cross directions (MD and CD). The strips are 1 inch wide and approximately 8 inches long. The specimen is loaded into a tensile test frame using line grip jaws (flat rubber on one side of the jaws and line grip on the other side) set at a gauge length (distance from line grip to line grip) of 2 inches. The specimen is then strained at a crosshead speed of 20 inches / min. From the resulting stress-strain curve, the modulus of elasticity (often called Young's modulus from the first part of the stress-strain curve) and the secant modulus at 1% strain and 2% strain are calculated.

[0076] Gel Permeation Chromatography (GPC) Molecular weights (Mw, Mz, Mn, etc.) were measured using GPC unless otherwise indicated.

[0077] The chromatography system consisted of a PolymerChar (Valencia, Spain) GPC-IR high temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler oven compartment was set at 160°C and the column compartment was set at 150°C. The columns used were four Agilent "Mixed A" 30 cm, 20 micrometer linear mixed bed columns. The chromatography solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume employed was 200 microliters and the flow rate was 1.0 milliliters / min.

[0078] Calibration of the GPC column set was performed with 21 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000, arranged in six "cocktail" mixtures with at least 10-fold spacing between individual molecular weights. Standards were purchased from Agilent Technologies. Polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000, and at 0.05 grams in 50 milliliters of solvent for molecular weights less than 1,000,000. The polystyrene standards were dissolved at 80° C. for 30 minutes with gentle agitation. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)). M ポリエチレン =A×(M ポリスチレン ) B (Formula 1) where M is the molecular weight, A has a value of 0.4315, and B is equal to 1.0.

[0079] A fifth order polynomial was used to fit each of the polyethylene equivalent calibration points, with a small adjustment to A (approximately 0.375 to 0.445) to correct for column resolution and band broadening effects for a linear homopolymer polyethylene standard obtained at 120,000 Mw.

[0080] Total plate counts of the GPC column set were performed using decane (prepared at 0.04 g in 50 milliliters of TCB and dissolved for 20 minutes with gentle agitation). Plate counts (Equation 2) and symmetry (Equation 3) were measured with a 200 microliter injection according to the following equations:

[0081]

number

[0082]

number

[0083] Samples were prepared in a semi-automated fashion using PolymerChar's "Instrument Control" software to target sample weights of 2 mg / mL and add solvent (containing 200 ppm BHT) via a PolymerChar high temperature autosampler to pre-nitrogen sparged capped vials with septa. Samples were dissolved at 160° C. for 2 hours under "slow" shaking.

[0084] Mn (GPC) , Mw (GPC) , and Mz (GPC) The calculation was based on GPC results using PolymerChar's GPCOne™ software, the baseline-subtracted IR chromatogram at each equally spaced data collection point (i), and the polyethylene equivalent molecular weight obtained from a narrow standard calibration curve for point (i) of Equation 1, according to Equations 4-6, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph.

[0085]

number

[0086] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (flow rate (apparent)) of each sample by RV matching the respective decane peak in the sample (RV (FM sample)) with that of the decane peak in the narrow standard calibration (RV (FM calibrated)). Any change in time of the decane marker peak is then assumed to be related to a linear shift in flow rate (flow rate (effective)) throughout the run. To facilitate the highest accuracy of the RV measurement of the flow rate marker peak, a least squares fitting routine is used to fit the peaks of the flow rate marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation is then used to solve for the true peak position. After calibrating the system based on the flow rate marker peak, the effective flow rate (relative to the narrow standard calibration) is calculated as per Equation 7: Processing of flow marker peaks was performed via GPCOne™ software from PolymerChar, Inc. Acceptable flow correction is such that the effective flow rate should be within ±1% of the apparent flow rate. Flow (effective) = Flow (apparent) × (RV(FM calibrated) / RV(FM sample)) (Equation 7) EXAMPLES

[0087] The following examples illustrate features of the present disclosure but are not intended to limit the scope of the disclosure.

[0088] A 5-layer biaxially oriented polyethylene film was produced using a 2.1 meter wide pilot tenter frame line. The film was produced using a 5-layer (ADBDC) die with an approximate die gap of 3.1 mm, cast onto a chilled drum using an air knife pinner. The film is stretched through a series of heated differential speed rolls in the machine direction at a stretch ratio of 5.5 to 6.0:1, followed by a stretch ratio of 8:1 in the transverse direction. The configuration of each extruder is shown in Table 2 below.

[0089] [Table 2]

[0090] A multilayer film having a width of 280 mm to 290 mm and a thickness of 0.8 mm to 1.0 mm was coextruded through a five-layer die at a processing temperature of about 240 °C to 260 °C and cast onto a cooling drum with a surface temperature controlled at 40 °C to 90 °C to solidify the unoriented film at a casting speed of about 4 meters per minute to 6 meters per minute. The unoriented film was preheated in the machine direction during stretching at about 65 °C to 130 °C and stretched in the machine direction at about 110 °C to 130 °C with a stretch ratio of 5 to 6 times the original length. The resulting stretched sheet was annealed at about 30 °C to 70 °C to reduce heat shrinkage and obtain a uniaxially oriented film.

[0091] The uniaxially oriented film was introduced into a tenter at a line speed of about 20 meters per minute to 28 meters per minute, preheated at about 140°C to 155°C, stretched in the transverse direction at about 120°C to 130°C with a stretch ratio of about 6 to 8 times the original width, and then heat set or annealed at about 105°C to 120°C to reduce the internal stress due to orientation, minimize the thermal shrinkage of the final film, and obtain a relatively heat stable biaxially oriented film. After biaxial orientation, the thickness of the coextruded film was nominally about 20 micrometers overall, with the outer layers (extruders A and C) each being about 1 micrometer thick, the tie layer (extruder D, split into two layers) each being about 0.65 micrometers to 0.8 micrometers thick, and the core layer (extruder B) being about 16 micrometers to 17 micrometers thick. The biaxially oriented multilayer film may be wound into a roll. The machine direction orientation relaxation rate may be 3% to 5%, and the transverse direction orientation relaxation rate may be 3% to 6%.

[0092] In all experiments, the core layer (Extruder B) and the tie layer (Extruder D) used the same HDPE material. The skin layers (Extruders A and C) used the same LLDPE material. The final film width was approximately 1.1 m.

[0093] The LLDPE material used for the skin layers was INNATE™ TF80 from The Dow Chemical Company, having a melt index of 1.7 g / 10 min and a density of 0.926 g / cc. The properties of the HDPE materials used for the tie and core layers are listed below in Table 3. HDPE-1 was a bimodal HDPE produced via a dual reactor process according to the process described in Example 6 of U.S. Patent No. 8,445,594, which is incorporated herein by reference in its entirety.

[0094] [Table 3]

[0095] In particular, HDPE-1 was made using a dual sequential polymerization system comprising a first gas-phase reactor and a second gas-phase reactor operated in series. The reactor contained ethylene, one or more α-olefin comonomers, hydrogen, a Ziegler-Natta catalyst slurried in mineral oil, N 2 , and isopentane were continuously fed to the first reactor. Subsequently, triethylaluminum (TEAL) cocatalyst was continuously fed to the first reactor to activate the catalyst. A first polymerization reaction of ethylene in the presence of 1-hexene was then carried out in the first reactor under the conditions shown in Table 4 below, thereby producing a first component-catalyst complex. The first component-catalyst complex was continuously transferred to the second reactor. Additional ethylene, hydrogen, TEAL cocatalyst, N 2 , and isopentane were continuously fed to the second reactor. No additional catalyst was added to the second reactor. A second polymerization reaction of ethylene was carried out in the second reactor under the conditions shown in Table 4 below, thereby producing a first component-catalyst-second component composite. The first component-catalyst-second component composite was removed in batches from the second reactor into a product chamber, purged to remove residual hydrocarbons, and then transferred to a drum. The drum was purged with humidified nitrogen.

[0096] [Table 4]

[0097] The polymer was further processed in a mixer / pelletizer. Additional additives such as 400 ppm Irganox 1010 and 500 ppm Irgafos 168 were added to the polymer. The polymer was melted in the mixer and the additives were dispersed therein.

[0098] HDPE-A was a bimodal HDPE made by a dual solution reactor process. HDPE-B was a unimodal HDPE made by a single reactor process with a chromium type catalyst. HDPE-C was a bimodal HDPE produced via a dual solution reactor process according to the process described in International Application PCT / US2021 / 024140, which is incorporated herein by reference in its entirety.

[0099] The formulations of Example 1, Comparative Example A, Comparative Example B, and Comparative Example C prepared according to the embodiments disclosed and described herein are listed in Table 5. Table 5 also includes the stretching performance in TDO, web appearance after TDO, torque requirement in main core extruder B, and the haze and elastic modulus of each film. As shown in Table 5, the samples with HDPE 1 in the tie layer and core layer showed the best stretching stability in TDO, low web sag after TDO, most uniform web appearance, and low gauge variation at the same time. Stretching stability, web appearance, and low gauge variation are listed as the most important requirements for producing high quality BOPE films on large industrial scale tenter frame lines. The samples using HDPE 1 also required low torque in the main core extruder, which is also important for maintaining high throughput in large industrial scale tenter frame lines.

[0100] [Table 5] * Ranking of stretch stability in TDO: 1-best, 4-worst

[0101] It will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, as defined in the appended claims. More specifically, although certain aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to those aspects.

Claims

1. 1. A film comprising at least one layer, said at least one layer comprising: A melt index (I) of 0.8 g / 10 min to 5.0 g / 10 min ２ )and, a density between 0.950 g / cc and 0.965 g / cc; a polydispersity (Mw / Mn) of 10 to 20; and a molecular weight (Mz) of 500,000 g / mol to 1,000,000 g / mol; the film is a biaxially oriented polyethylene film; The film is stretched in the machine direction at a stretch ratio of 5 to 6 times its original length and in the transverse direction at a stretch ratio of 6 to 8 times its original width.

2. The multimodal high density polyethylene has a melt index (I ２ 10. The film of claim 1, comprising:

3. 10. The film of claim 1, wherein the multimodal high density polyethylene comprises a density that is from 0.955 g / cc to 0.960 g / cc.

4. 10. The film of claim 1, wherein the multimodal high density polyethylene comprises a polydispersity (Mw / Mn) that is 10-15.

5. 10. The film of claim 1, wherein the multimodal high density polyethylene comprises a molecular weight Mz of from 550,000 g / mol to 900,000 g / mol.

6. The multimodal high density polyethylene has a melt index ratio (I １０ / I ２ 10. The film of claim 1, comprising:

7. 10. The film of claim 1, wherein the multimodal high density polyethylene comprises a molecular weight Mw that is from 110,000 g / mol to 135,000 g / mol.

8. 10. The film of claim 1, wherein the multimodal high density polyethylene comprises a molecular weight Mn of from 9,000 g / mol to 10,000 g / mol.

9. A biaxially oriented multilayer film, A core layer comprising a multimodal high density polyethylene, the multimodal high density polyethylene comprising: A melt index (I) of 0.8 g / 10 min to 5.0 g / 10 min ２ )and, a density between 0.950 g / cc and 0.965 g / cc; a polydispersity (Mw / Mn) of 10 to 20; a molecular weight (Mz) of 500,000 g / mol to 1,000,000 g / mol; and a first layer positioned on a first side of the core layer; a second layer positioned on a second side of the core layer.

10. At least one of the first layer and the second layer comprises: A melt index (I) of 0.8 g / 10 min to 5.0 g / 10 min ２ )and, a density between 0.950 g / cc and 0.965 g / cc; a polydispersity (Mw / Mn) of 10 to 20; 10. The biaxially oriented multilayer film of claim 9, comprising a multimodal high density polyethylene comprising: and a molecular weight (Mz) of from 500,000 g / mol to 1,000,000 g / mol.

11. 10. The biaxially oriented multilayer film of claim 9, wherein the first layer and the second layer are made from the same material.

12. a first side of the first layer positioned on the first side of the core layer and a first side of the second layer positioned on the second side of the core layer; a third layer positioned on a second side of the first layer; 10. The biaxially oriented multilayer film of claim 9, wherein a fourth layer is positioned on the second side of the second layer.

13. 10. The biaxially oriented multilayer film of claim 9, wherein the multilayer film comprises a haze of 2% to 70%.

14. 10. The biaxially oriented multilayer film of claim 9, wherein the multilayer film comprises a 1% secant modulus in MD (machine direction) of 500 MPa to 2500 MPa.

15. An article comprising the film of claim 1 or the multilayer film of claim 9.