Polyethylene-containing oriented film

Abstract

The present invention provides an oriented film and a process for producing an oriented film. The process for producing an oriented film according to the embodiments disclosed herein includes providing low-density polyethylene and an ethylene copolymer, extruding the low-density polyethylene into a first outer layer and the ethylene copolymer into an inner layer to form a multilayer film, and oriented the film to obtain a specific thickness in the first outer layer. The resulting oriented film can provide desirable properties, among other things, such as a heat seal initiation temperature and recyclability.

Description

[Technical Field]

[0001] (Field of Invention) Embodiments of this disclosure generally relate to orientation films and processes for manufacturing the same.

[0002] (Introduction) Oriented films are developing as one of the main technological solutions for packaging. Orientation of a film in the mechanical direction (MDO), transverse direction, or both directions (i.e., biaxially oriented films) can improve properties such as optics, tensile strength, stiffness, low elongation, and heat resistance. While oriented films are typically used as printing substrates for forming laminates, the demand for single-film solutions continues to rise, as does the demand for thinner, more sustainable, and recyclable films made from a single material. Oriented film and single-film packaging solutions have specific challenges in achieving a low heat seal initiation temperature (HSIT) while maintaining other desirable properties. To orient a film, the extruded film is typically heated to high temperatures, for example, by rapidly passing it through a heated chrome roller to achieve optimal heat transfer, resulting in the polymer in the film being in a semi-molten state suitable for stretching. When a sealant resin that provides a low HSIT is extruded as the outer layer of an oriented film, a lower temperature and slower manufacturing process is required because the film tends to stick to the roller. Therefore, there is still a strong need for an oriented film that can provide a desired heat seal initiation temperature while maintaining other properties, can provide a solution for a single monomaterial, and can be rapidly processed at high temperatures for stretching. [Overview of the Initiative]

[0003] Embodiments of the present disclosure satisfy the aforementioned needs by providing an orientation film that can achieve low heat seal initiation, is recyclable, and can be used as a single solution.

[0004] This specification discloses a process for manufacturing an alignment film. The process for manufacturing an alignment film includes providing a low-density polyethylene having a density of 0.910 to 0.940 g / cm 3 and an ethylene copolymer having a maximum peak melting temperature (T m ) of 105°C or lower; extruding a first outer layer having a thickness of "X" and containing low-density polyethylene, an inner layer adjacent to the first outer layer and containing an ethylene copolymer, and a second outer layer to form a film including at least three layers; and orienting the film in at least one direction, wherein the film is oriented at a draw ratio "Y", and when the thickness "X" is divided by Y, the result is less than 0.45.

[0005] Also, this specification discloses a process for manufacturing a laminate. The process for manufacturing a laminate includes fabricating an alignment film according to the embodiments disclosed in this specification and adhering the alignment film to a substrate film with an adhesive.

[0006] An alignment film is also disclosed in this specification. The alignment film can be manufactured by the above process. The alignment film includes a first outer layer containing low-density polyethylene having a density of 0.910 to 0.940 g / cm 3 ; an inner layer adjacent to the first outer layer and containing an ethylene copolymer having a maximum peak melting temperature (T m ) of 105°C or lower, and a second outer layer, wherein the first outer layer has a thickness of less than 0.45 microns.

[0007] These and other embodiments will be described in more detail in the "Detailed Description of the Invention".

Detailed Description of the Invention

[0008] The embodiments of the disclosed film are described in more detail below. The orientation films of this disclosure may have a wide variety of packaging applications, including, for example, pouches, stand-up pouches, pillow pouches, bulk bags, pre-fabricated packaging, sachets, and lidding films.

[0009] As used herein, the term “polymer” means a polymer compound prepared by polymerizing monomers, whether of the same or different types. Thus, the general term polymer encompasses the terms homopolymer (used to refer to a polymer prepared from only one type of monomer) and copolymer or interpolymer. Trace amounts of impurities (e.g., catalyst residue) may be incorporated into and / or present within the polymer. A polymer may be a single polymer, a polymer blend, or a polymer mixture comprising a mixture of polymers formed in situ during polymerization.

[0010] As used herein, the terms “polyethylene” or “ethylene polymer” shall mean a polymer containing units derived from a majority (more than 50 mol%) of 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), single-site catalyst linear low-density polyethylene (m-LLDPE) including both linear low-density resins and substantially linear low-density resins, ethylene plastomers (POP) and ethylene elastomers (POE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). These polyethylene materials are generally known in the art. However, the following explanation may help in understanding the differences between some of these different polyethylene resins.

[0011] The term "LDPE" may also be referred to as "high-pressure ethylene polymer" or "highly branched polyethylene," but is defined to mean that the polymer is partially or completely homopolymerized or copolymerized in an autoclave or tubular reactor at a pressure exceeding 14,500 psi (100 MPa) using a free radical initiator such as a peroxide (see, for example, U.S. Patent No. 4,599,392, incorporated herein by reference). LDPE resins typically have a viscosity of 0.916–0.935 g / cm³. 3 It has a density within the range.

[0012] The term "LLDPE" includes both resins made using single-site catalysts including, but not limited to, traditional Ziegler-Natta catalyst systems and chromium-based catalysts, and mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), geometrically constrained catalysts, phosphine imine catalysts, and polyvalent aryloxy ether catalysts (typically referred to as bisphenol phenoxy), and includes linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains fewer long-chain branches than LDPE and includes substantially linear ethylene polymers further defined in U.S. Patent No. 5,272,236, U.S. Patent No. 5,278,272, U.S. Patent No. 5,582,923, and U.S. Patent No. 5,733,155, homogeneous branched linear ethylene polymer compositions such as those of U.S. Patent No. 3,645,992, heterogeneous branched ethylene polymers prepared according to the process disclosed in U.S. Patent No. 4,076,698, and / or blends thereof (such as those disclosed in U.S. Patent No. 3,914,342 or U.S. Patent No. 5,854,045). LLDPE can 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.

[0013] As used herein, the term "polyethylene elastomer / plastomer" means a substantially linear or linear ethylene / α-olefin copolymer containing a homogeneous short-chain branch distribution containing units derived from ethylene and units derived from at least one C3-C 10 α-olefin comonomer, or at least one C4-C8 α-olefin comonomer, or at least one C6-C8 α-olefin comonomer. The polyethylene elastomer / plastomer has a density of 0.865 g / cm 3 , or 0.870 g / cm 3 , or 0.880 g / cm 3 , or 0.890 g / cm 3 ~0.900 g / cm 3 , or 0.902 g / cm3 , or 0.904 g / cm³ 3 , or 0.909 g / cm³ 3 , or 0.910 g / cm³ 3 It has a density of . Non-limiting examples of polyethylene elastomers / plastomers include AFFINITY® plastomers and elastomers (available from The Dow Chemical Company), EXACT® plastomers (available from ExxonMobil Chemical), Tafmer (available from Mitsui), Nexlene® (available from SK Chemicals Co.), and Lucene® (available from LG Chem Ltd.).

[0014] The terms “comprising,” “including,” and “having,” and their derivatives, are not intended to exclude the presence of any additional components, processes, or procedures, whether or not they are specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term “comprising” may, unless otherwise specified, include any additional additives, adjuvants, or compounds, whether polymeric or otherwise. In contrast, the term “consisting essentially of” excludes any other components, processes, or procedures from the scope of any subsequent description, except those not essential to operability. The term “consisting of” excludes any components, processes, or procedures not specifically described or listed.

[0015] Manufacturing process of orientation film and orientation film This specification discloses a manufacturing process for an oriented film. This process is for a film with a density of 0.910 to 0.940 g / cm³. 3 Low-density polyethylene having a density of 105°C or less, and a maximum peak melting temperature (T mThe invention provides an ethylene copolymer having ); a first outer layer containing low-density polyethylene having a thickness of "X", an inner layer adjacent to the first outer layer containing the ethylene copolymer, and a second outer layer, to form a film comprising at least three layers; and oriented the film in at least one direction, wherein the film is oriented with a stretch ratio "Y" and the thickness "X" divided by Y is less than 0.45. In some embodiments, the film is oriented in the machine direction. In some embodiments, the film is oriented in the transverse direction. In some embodiments, the film is oriented in the machine direction with a stretch ratio of 4:1 to 12:1 and in the transverse direction with a stretch ratio of 4:1 to 12:1. In some embodiments, the first outer layer is less than 2% of the total thickness of the film, and the thickness of the first outer layer is calculated using the formula X divided by Y.

[0016] The oriented films disclosed herein can be formed using the processes described above and below. The oriented film comprises at least three layers, namely a first outer layer, an inner layer adjacent to the first outer layer, and a second outer layer. The term “adjacent” means that there is no intervening layer between the inner layer and the first outer layer. The oriented film may comprise four, five, six, seven, eight, nine, ten or more layers, and may include additional layers such as a binding layer or a barrier layer. The oriented film may have an A / B / C structure, in which case the first outer layer is “A”, the inner layer is “B”, and the second outer layer is “C”. The oriented film according to the embodiments disclosed herein may have an A / B / C / D / E structure, in which case A is the first outer layer, B is the inner layer, C is the filler layer, D is the binding layer, and E is the second outer layer and barrier layer.

[0017] The orientation film includes a first outer layer. The first outer layer has a thickness "X" when extruded and before orientation and stretching. In some embodiments, the first outer layer has a thickness of less than 10.00 microns, or less than 8.00 microns, or less than 5.00 microns, or less than 3.00 microns, or less than 2.60 microns when extruded and before orientation and stretching. In some embodiments, the first outer layer (after orientation) has a thickness of less than 0.45 microns, or less than 0.43 microns, or less than 0.40 microns, or less than 0.38 microns, or less than 0.35 microns, or less than 0.33 microns, or less than 0.31 microns, or less than 0.29 microns, or less than 0.27 microns, or less than 0.25 microns.

[0018] The thickness of the first outer layer after orientation depends on the degree to which the film is oriented or stretched. In some embodiments, the film is oriented in at least one direction with a stretch ratio to achieve a “calculated” thickness of less than 0.45 microns. For example, an extruded outer layer having a thickness of 2.00 microns before orientation and stretching, and then being stretched to a ratio of 5:1, has a calculated thickness of 0.40 microns. This relationship between thickness and orientation or stretch ratio is expressed herein as thickness “X” and stretch ratio “Y”, where the stretch ratio Y is the product of the stretch ratios in both the machine direction and the transverse direction. For example, if the extruded first outer layer has a thickness “X” of 2.00 microns before orientation and stretching, and the film is then stretched 2:1 in the machine direction and 4:1 in the transverse direction, the “Y” value is 8 (2 × 4), and the calculated thickness X / Y is 2.00 microns / 8 = 0.25 microns. The stretch ratio is greater than 1 because the film is an oriented film. In some embodiments, the first outer layer has a calculated thickness of less than 0.45 microns, or less than 0.43 microns, or less than 0.40 microns, or less than 0.38 microns, or less than 0.35 microns, or less than 0.33 microns, or less than 0.31 microns, or less than 0.29 microns, or less than 0.27 microns, or less than 0.25 microns.

[0019] In some embodiments, the first outer layer has a specific weight percentage-to-stretch ratio relationship. For example, in some embodiments, the weight percentage of the first outer layer based on the total weight of the film is less than 0.35, less than 0.30, less than 0.25, or less than 0.20 with respect to the product of the stretch ratios.

[0020] In some embodiments, the first outer layer constitutes less than 10.0% by weight, or less than 5.0% by weight, or less than 3.0% by weight, or less than 2.5% by weight, or less than 2.0% by weight, or less than 1.5% by weight of the total film weight, based on the total weight of the film. In some embodiments, the first outer layer, after orientation, constitutes less than 3.0% of the total thickness of the film, or less than 2.0% of the total thickness of the film, or less than 1.5% of the total thickness of the film, or less than 1.0% of the total thickness of the film, or less than 0.5% of the total thickness of the film.

[0021] The first outer layer has a density of 0.910-0.940 g / cm³. 3 It contains low-density polyethylene having a density of 0.910, 0.913, 0.915, 0.918, 0.924, 0.930, 0.933, 0.935, or 0.937 g / cm³. 3 From the lower limit, 0.915, 0.920, 0.925, 0.930, 0.935, or 0.940 g / cm³ 3 It may have a density up to the upper limit. In some embodiments, low-density polyethylene is LDPE. In some embodiments, low-density polyethylene is a low-density polyethylene homopolymer polymerized under high pressure. In other embodiments, low-density polyethylene is LLDPE.

[0022] In some embodiments, low-density polyethylene has a maximum peak melting temperature (T) above 105°C, above 110°C, above 115°C, or above 120°C. m ) has.

[0023] In some embodiments, the low-density polyethylene has a melt index (I2) of 0.2 to 50.0 g / 10 min, or 0.3 to 40.0 g / 10 min, or 0.4 to 30.0 g / 10 min, or 0.5 to 20.0 g / 10 min, or 0.5 to 10 g / 10 min, or 0.5 to 5.0 g / 10 min.

[0024] In some embodiments, the first outer layer is essentially made of low-density polyethylene, or alternatively, consists solely of low-density polyethylene. In other embodiments, the first outer layer may contain additional polymers other than low-density polyethylene. For example, in some embodiments, the first outer layer may consist of a blend of low-density polyethylene with another polymer such as ULDPE, VLDPE, LLDPE, LDPE, MDPE, or HDPE. In some embodiments, the first outer layer contains (of comprises) at least 90% by weight of low-density polyethylene. All individual values ​​and partial ranges of at least 90% by weight are disclosed and included herein. For example, in some embodiments, the first outer layer may contain at least 90% by weight, at least 95% by weight, at least 99% by weight, at least 99.5% by weight, or 90% to 100% by weight, or 95% to 99% by weight, or 90% to 99.9% by weight of low-density polyethylene, based on the total weight of the polymers in the first outer layer. In some embodiments, the first outer layer contains at least 90% by weight, at least 95% by weight, at least 99% by weight, at least 99.5% by weight, or 90% to 100% by weight, or 95% to 99% by weight, or 90% to 99.9% by weight of an ethylene-based polymer, based on the total weight of the polymer in the first outer layer.

[0025] Examples of commercially available low-density polyethylenes that can be used for the first outer layer include those from Dow Chemical Company, such as ELITE® 5400 GS, ELITE® 5401 GT, DOWLEX® 2045G, DOW® LDPE 410E, and AGILITY® EC 7000, and those from Exxon Mobil Company, such as Exceed® 1018, Exceed® XP 8318, and LDPE LD158BW.

[0026] The orientation film includes an inner layer adjacent to the first outer layer. The inner layer has a maximum peak melting temperature (T) of 105°C or lower. m The ethylene copolymer has a maximum peak melting temperature (T) of 100°C or less, or 95°C or less, or 90°C or less, or 85°C or less. m ) has. In some embodiments, the ethylene copolymer has a density of less than 0.905 g / cc, or less than 0.900 g / cc, or less than 0.895 g / cc, or less than 0.890 g / cc, or less than 0.888 g / cc, or in the range of 0.855 to 0.905 g / cc, 0.860 to 0.905 g / cc, 0.865 to 0.905 g / cc, or 0.880 to 0.900 g / cc, or 0.880 to 0.895 g / cc. In some embodiments, the ethylene copolymer is a polyethylene elastomer / plastomer. In further embodiments, the ethylene copolymer is a polyethylene elastomer / plastomer having a density of less than 0.900 g / cc or less than 0.895 g / cc. In some embodiments, the inner layer has a maximum peak melting temperature (T) of 100°C or less, or 95°C or less, or 90°C or less, or 85°C or less. m ) has.

[0027] In some embodiments, the ethylene copolymer has a melt index (I2) of less than 10.0 g / 10 min, or less than 5.0 g / 10 min, or less than 4.0 g / 10 min, or less than 3.0 g / 10 min, or less than 2.0 g / 10 min.

[0028] In some embodiments, the inner layer has a maximum peak melting temperature (T) of 105°C or less, based on the total weight of the polymer in the inner layer. m The inner layer contains at least 70% by weight of an ethylene copolymer having ). All individual values ​​and partial ranges of at least 70% by weight are disclosed and included herein. For example, in some embodiments, the inner layer may contain at least 70% by weight, at least 80% by weight, at least 90% by weight, at least 95% by weight, at least 99% by weight, at least 99.5% by weight, or 70% to 100% by weight, 75% to 99% by weight, 80% to 95% by weight, or 90% to 95% by weight of an ethylene copolymer, based on the total weight of the polymer in the inner layer. In some embodiments, the inner layer is essentially made of or consists of an ethylene polymer, based on the total weight of the polymer in the inner layer. In some embodiments, the inner layer does not contain polyolefins other than ethylene copolymers.

[0029] In some embodiments, the inner layer ethylene copolymer is selected from the group consisting of polyethylene plastomer / elastomer, ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, ethylene methyl acrylate copolymer, or ethylene ethyl acrylate copolymer.

[0030] In some embodiments, the inner layer has a maximum peak melting temperature (T) of 100°C or less. m It contains at least 70% by weight of polyethylene elastomer / plastomer having ) ). In such embodiments, the inner layer polyethylene elastomer / plastomer has a density of 0.855 to 0.910 g / cm³ 3 It can have a density in the range of 0.855~0.910 g / cm³. 3 All individual values ​​and partial ranges of the density are disclosed and included herein, for example, polyethylene elastomer / plastomer is 0.865 to 0.910 g / cm³. 3 , 0.865~0.900 g / cm³ 3 , 0.865~0.890 g / cm³ 3 , 0.865~0.880 g / cm³3 , 0.865~0.870 g / cm³ 3 , 0.870~0.910 g / cm³ 3 , 0.870~0.900 g / cm³ 3 , 0.870~0.890 g / cm³ 3 , 0.870~0.880 g / cm³ 3 , 0.880~0.910 g / cm³ 3 , 0.880~0.900 g / cm³ 3 , 0.880~0.890 g / cm³ 3 , 0.890~0.910 g / cm³ 3 , 0.890~0.900 g / cm³ 3 , or 0.900~0.910 g / cm³ 3 It may have a density within that range.

[0031] In embodiments in which the inner layer includes a polyethylene elastomer / plastomer, the polyethylene elastomer / plastomer may have a melt index (I2) in the range of 0.50 to 20 g / 10 min. All individual values ​​and partial ranges of the melt index (I2) from 0.50 to 20 g / 10 min are disclosed and included herein, for example, the polyethylene elastomer / plastomer may have a melt index (I2) from a lower limit of 0.50, 1.0, 2.0, 5.0, 10.0, 15, or 18 g / 10 min to an upper limit of 1.0, 2.0, 5.0, 10.0, 15, 18, 19, or 20 g / 10 min.

[0032] Examples of commercially available polyethylene elastomers / plastomers that can be used for the inner layer include, for example, those marketed under the name AFFINITY® by The Dow Chemical Company (Midland, MI), such as AFFINITY® VP 8770G1, AFFINITY® PF7266, AFFINITY® PL 1881G, and AFFINITY® PF1140G.

[0033] In addition to the ethylene copolymer, the inner layer may, in some embodiments, further contain at least one additional polymer and / or at least one additive. For example, the at least one additional polymer may be selected from the group consisting of LDPE, LLDPE, or combinations thereof, in an amount of less than 30% by weight of the inner layer. For example, the at least one additive may be selected from the group consisting of antioxidants, UV stabilizers, heat stabilizers, slip agents, anti-tack agents, antistatic agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, foaming agents, or combinations thereof, in an amount of less than 30% by weight of the inner layer. In some embodiments, the inner layer contains 0.1-10% by weight, 0.5-8% by weight, 1.0-7.5% by weight, or 2.5-7.5% by weight of additives, such as slip and anti-tack masterbatch additives. In embodiments in which the inner layer contains polymers other than the ethylene copolymer, the maximum peak melting temperature of the inner layer is 105°C or less.

[0034] In some embodiments, the oriented inner layer is at least 10 microns thick, or alternatively at least 15 microns thick, or alternatively at least 20 microns thick. In further embodiments, the inner layer is 25-60% of the total thickness of the oriented film.

[0035] The orientation film includes a second outer layer. The second outer layer is not particularly limited herein. The second outer layer may include low-density polyethylene having the same characteristics or properties as the low-density polyethylene of the first outer layer. The second outer layer has a thickness-to-stretch ratio similar to or the same as that of the first outer layer. The second outer layer may include LDPE, LLDPE, MDPE, HDPE, or a combination thereof. In some embodiments, the second outer layer may include polyamide or polypropylene.

[0036] In some embodiments, the multilayer film includes a bonding layer, and the second outer layer is a barrier layer. In such embodiments, the orientation film includes a bonding layer between the inner layer and the second outer layer.

[0037] In embodiments where the binding layer is located between the inner layer and the second outer layer, the second outer layer, acting as a barrier layer, may include ethylene vinyl alcohol copolymer (EVOH).

[0038] Various total thicknesses are intended for the orientation film. In some embodiments, the second layer, acting as a barrier layer, may be 5-25% of the total thickness of the multilayer film.

[0039] In embodiments where a bonding layer exists between the inner layer and the second outer layer, the bonding layer may include an adhesive resin selected from the group consisting of anhydride-grafted ethylene polymers, ethylene acid copolymers, and ethylene vinyl acetate. Examples of anhydride-grafted portions include maleic anhydride, citraconic anhydride, 2-methylmaleic anhydride, 2-chloromaleic anhydride, 2,3-dimethylmaleic anhydride, bicyclo[2,2,1]-5-heptane-2,3-dicarboxylic acid anhydride and 4-methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, bicyclo(2.2.2)octo-5-ene-2,3-dicarboxylic acid anhydride, and lo-octahydronaphthalene-2,3-dicarboxylic acid anhydride. Examples include, but are not limited to, 2-oxa-1,3-diketospiro(4.4)nona-7-ene, bicyclo(2.2.1)hepta-5-ene-2,3-dicarboxylic acid anhydride, tetrahydrophthalic anhydride, norbol-5-ene-2,3-dicarboxylic acid anhydride, nadic anhydride, methylnadic anhydride, himic anhydride, methylhimic anhydride, and x-methyl-bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride. In one embodiment, the anhydride grafting portion includes maleic anhydride.

[0040] In some embodiments, the binding layer comprises anhydrous-modified linear low-density polyethylene. In some embodiments, the anhydrous-modified linear low-density polyethylene is 0.860 g / cm³ 3 ~0.935g / cm 3 It has a density in the range of 0.860 g / cm³. 3 ~0.935g / cm 3All individual values ​​and partial ranges of are disclosed and included herein, for example, anhydrous modified linear low-density polyethylene is 0.875 g / cm³. 3 ~0.935g / cm 3 , 0.900 g / cm³ 3 ~0.925g / cm 3 , 0.910 g / cm³ 3 ~0.935g / cm 3 , 0.910 g / cm³ 3 ~0.925g / cm 3 , 0.915 g / cm³ 3 ~0.935g / cm 3 , or 0.920 g / cm³ 3 ~0.930g / cm 3 It may have a density in the range of . In some embodiments, the anhydrous modified linear low-density polyethylene has a melt index (I2) of 0.1 g / 10 min to 50 g / 10 min, or 0.5 g / 10 min to 20 g / 10 min, or 1.0 g / 10 min to 10 g / 10 min.

[0041] In some embodiments, the orientation film can be bonded to a substrate, such as another film, to form a laminate. The laminate comprises the orientation film, adhesive, and substrate according to embodiments disclosed herein. The adhesive can be applied to the outermost layer of the orientation film (e.g., a barrier layer in one embodiment, or a second outer layer in another embodiment) to act as an adhesive layer, thereby bonding the orientation film to a substrate, such as a polyethylene film. Processes for manufacturing the laminate are also disclosed herein. The process for manufacturing the laminate includes preparing the orientation film according to embodiments disclosed herein and bonding the orientation film to a substrate film with the adhesive.

[0042] In some embodiments, the adhesive is a solvent-based adhesive, a solvent-free adhesive, or a water-based adhesive. Examples of commercially available adhesives that may be used in some embodiments include those available from The Dow Chemical Company (Midland, MI) under the names ADCOTE®, MOR-FREE®, and ROBOND®.

[0043] In some embodiments, the orientation film is a machine-direction oriented film. In such embodiments, the orientation film may be a machine-direction oriented (MDO) polyethylene film. In some embodiments, the orientation film is machine-direction oriented with a stretch ratio of 4:1 to 12:1 or 5:1 to 10:1. The MDO film is a uniaxially oriented film. The stretching or orientation of the film is performed by machine-direction oriented rolls, via widthening or via meshing gears, thereby ring-rolling the film or otherwise progressively stretching it in the machine direction.

[0044] In other embodiments, the orientation film is biaxially oriented. In such embodiments, the orientation film may be a biaxially oriented polyethylene (BOPE) film. In embodiments where the orientation film is BOPE, the BOPE may be biaxially oriented using a tenter frame sequential biaxial orientation process and may be referred to as tenter frame biaxially oriented polyethylene (TF-BOPE). Such techniques are generally known to those skilled in the art. In other embodiments, the orientation film may be biaxially oriented using other techniques known to those skilled in the art, such as a double-cell orientation process, based on the teachings herein. Generally, using a tenter frame sequential biaxial orientation process, the tenter frame is incorporated as part of a multilayer co-extrusion line. After extrusion from a flat die, the film is cooled on a cooling roll and immersed in a water bath filled with room temperature water. The cast film is then passed over a series of rollers having different rotational speeds to achieve stretching in the machine direction. The MD stretching segment of the production line has several pairs of rollers, all of which are oil heated. The pair of rollers operate sequentially as preheating rollers, stretching rollers, and rollers for relaxation and annealing. 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 furnace with heating zones to perform stretching in the transverse direction. The first few zones are for preheating, followed by stretching zones, and then a final zone for annealing.

[0045] In some embodiments, the orientation film has a transverse elongation ratio greater than its mechanical elongation ratio, and the orientation film has a ratio of at least 2:1 of mechanical elongation at break to transverse elongation at break.

[0046] In some embodiments, the orientation film can be oriented in the machine direction with a stretch ratio of 2:1 to 6:1, or alternatively, with a stretch ratio of 3:1 to 5:1. In some embodiments, the orientation film can be oriented transversely with a stretch ratio of 2:1 to 9:1, or alternatively, with a stretch ratio of 3:1 to 8:1. In some embodiments, the orientation film is oriented in the machine direction with a stretch ratio of 2:1 to 6:1 and transversely with a stretch ratio of 2:1 to 9:1. In some embodiments, the film is oriented in the machine direction, transversely, or both with a combined stretch ratio of at least 2:1 to achieve a calculated thickness of the first outer layer of less than 0.45 microns.

[0047] In some embodiments, depending on the end use, for example, the orientation film may be corona-treated or printed using techniques known to those skilled in the art.

[0048] The orientation film can have various thicknesses, for example, depending on the number of layers. For example, in some embodiments, the orientation film may have a thickness of 10 to 200 microns, or alternatively, 15 to 150 microns.

[0049] Oriented films can have superior heat-sealing performance compared to conventional films, and can be manufactured by stretching at a faster speed and at a better stretching temperature. In some embodiments, the oriented film has a heat-sealing start temperature of less than 105°C (defined as the seal temperature required to achieve a seal strength of 5 N / 15 mm according to the ASTM F88 method), or a heat-sealing start temperature of less than 104°C at 5 N / 15 mm.

[0050] In some embodiments, the orientation film contains, based on the total weight of polymers in the orientation film, at least 90% by weight of an ethylene-based polymer, or at least 95% by weight of an ethylene-based polymer, or at least 97% by weight of an ethylene-based polymer, or at least 99% by weight of an ethylene-based polymer, or at least 99.9% by weight of an ethylene-based polymer. In some embodiments, the orientation film contains, or does not contain, less than 5% by weight, or less than 3% by weight, or less than 1% by weight, or less than 0.1% by weight of other polyolefins other than polypropylene or ethylene-based polymers, based on the total weight of polymers in the orientation film.

[0051] additives It should be understood that any of the aforementioned multilayered layers may further contain one or more additives known to those skilled in the art, such as antioxidants, UV stabilizers, heat stabilizers, slip agents, anti-tack agents, antistatic agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, and foaming agents. For example, in the embodiment, the inner layer contains at least one of a slip agent or an anti-tack agent.

[0052] Goods Embodiments of the present invention also provide articles formed from the oriented films and laminates described herein. Examples of such articles include packaging, flexible packaging, and pouches. In some embodiments, the packaging of the present invention may include liquids, powders, food products, or other items. Articles and packaging of the present invention may be formed from the laminates disclosed herein using techniques known to those skilled in the art in consideration of the teachings herein.

[0053] Test method density Density was measured according to ASTM D792, in grams / cm³. 3 (g / cm 3 It is represented as ).

[0054] Melt Index (I2) The melting index (I2) is measured at 190°C using 2.16 kg according to ASTM D-1238. The value is reported as g / 10 min, corresponding to the grams eluted per 10 minutes.

[0055] Heat seal initiation temperature and seal strength Heat seal initiation temperature. To determine the heat seal initiation temperature (HSIT) and seal strength, the sample is sealed using a heat sealing device with opposing seal jaws. The sample width is 15 mm, the residence seal time is 0.5 seconds for thicknesses less than 100 microns, and the seal pressure is 2.5 kg / cm². The heat-sealed sample is allowed to set for 24 hours, and then measured using a tensile machine equipped with a 100 N load cell at a tensile speed of 500 mm / min. The HSIT is reported as the minimum temperature in degrees Celsius required to obtain a seal strength of 5 Newtons (50 kg). Heat seal strength. The heat seal strength, or seal strength, was measured according to ASTM F88. The value is reported in N / 15 mm.

[0056] Maximum peak melting temperature (Tm) Differential scanning calorimetry (DSC) is used to measure the melting and crystallization behavior of polymers over a wide temperature range. For example, this analysis is performed using a TA Instruments Q1000 DSC equipped with a refrigerated cooling system (RCS) and autosampler. The instrument is first calibrated using the software calibration wizard. A baseline is obtained by heating the cell from -80°C to 280°C with no sample in the aluminum DSC pan. Then, a sapphire standard is used according to the instructions of the calibration wizard. Next, 1-2 milligrams (mg) of fresh indium sample is analyzed by heating the standard sample to 180°C, cooling it to 120°C at a cooling rate of 10°C / min, and then keeping the standard sample isothermal at 120°C for 1 minute. Then, the standard sample is heated from 120°C to 180°C at a heating rate of 10°C / min. The indium standard sample is then subjected to the heat of fusion (H f It is determined that the saturation point is 28.71 ± 0.50 joules / gram (J / g) and the onset of melting is 156.6°C ± 0.5°C. Next, the test sample is analyzed using a DSC instrument.

[0057] During the test, a nitrogen purge gas flow rate of 50 mL / min is used. Each sample is melted and pressed at approximately 175°C to form a thin film, and then the molten sample is air-cooled to room temperature (approximately 25°C). A film sample of "0.1 to 0.2 grams" of the sample is formed by pressing at 175°C, 1,500 psi, and 30 seconds to form a film "0.1 to 0.2 mil thick". A test piece of 3 to 10 mg, 6 mm in diameter is extracted from the cooled polymer, weighed, placed in a light aluminum pan (approximately 50 mg), and sealed by pressing. Next, analysis is performed to determine its thermal properties.

[0058] The thermal behavior of the sample is determined by raising and lowering the sample temperature to create a heat flow versus temperature profile. First, the sample is rapidly heated to 180°C and held isothermally for 5 minutes to remove its thermal history. Next, the sample is cooled to -40°C at a cooling rate of 10°C / min and held isothermally at -40°C for 5 minutes. Then, the sample is heated to 150°C at a heating rate of 10°C / min (this is the "second heating" gradient). The cooling curve and the second heating curve are recorded. The cooling curve is analyzed by setting the baseline endpoint from the start of crystallization to -20°C. The thermal curve is analyzed by setting the baseline endpoint from -20°C to the end of melting. The determined value is the highest peak melting temperature (T m ), peak crystallization temperature (T c ), starting crystallization temperature (Tc start), heat of fusion (H f This is the crystallinity % calculated for polyethylene samples using (grams per joule), and the crystallinity % for PE = ((Hf) / (292J / g)) × 100, and the crystallinity % for polypropylene samples calculated using ((Hf) / 165J / g)) × 100. Heat of fusion (H f The peak melting temperature and the highest peak melting temperature are reported from the second thermal curve. The peak crystallization temperature and the onset crystallization temperature are determined from the cooling curve. [Examples]

[0059] The following embodiments illustrate the features of the present disclosure, but are not intended to limit the scope of the present disclosure.

[0060] Materials used The films of the examples discussed below contained the following materials:

[0061] AGILITY(TM)EC7000, 0.919g / cm 3 Density, melt index (I2) at 3.9 g / 10 min, and peak melting temperature (T) at 110°C. mLow-density polyethylene resin and LDPE, which have the properties of ) and are commercially available from The Dow Chemical Company (Midland, MI).

[0062] ELITE(TM) 5410GT, 0.917g / cm 3 Density, melt index (I2) at 1.0 g / 10 min, and peak melting temperature (T) at 123°C. m A low-density polyethylene resin that has ) and is commercially available from The Dow Chemical Company (Midland, MI).

[0063] XZ89810.00 (“XZ”), 0.902g / cm 3 A low-density polyethylene resin with a density of 0.85 g / 10 min and a melt index (I2), commercially available from The Dow Chemical Company (Midland, MI).

[0064] ELITE(TM) 5960G1, 0.962g / cm 3 A reinforced polyethylene resin with a density of 0.85 g / 10 min and a melt index (I2), commercially available from The Dow Chemical Company (Midland, MI).

[0065] ELITE(TM) 5940ST, 0.941g / cm 3 A reinforced polyethylene resin with a density of 0.8 g / 10 min and a melt index (I2), commercially available from The Dow Chemical Company (Midland, MI).

[0066] AFFINITY (trademark) VP 8770G1, maximum peak melting temperature of 82°C (T m ), 0.885 g / cm³ 3 Ethylene copolymers and polyethylene elastomers / plastomers commercially available from The Dow Chemical Company (Midland, MI), having a density and a melt index (I2) of 1.0 g / 10 min.

[0067] Polybatch FSU 105 E ("FSU") is a slip / stick prevention masterbatch commercially available from LyondellBasell.

[0068] The oriented films designated as Examples 1-2 and Comparative Examples 1-3 of the present invention are formed in a Windmoller & Holscher blow co-extrusion apparatus with the layer configurations and compositions shown in Table 1 below. Comparative Examples 1 and 2 have the following layer weight %: 10 / 10 / 15 / 10 / 10 / 10 / 15 / 10 / 10. Comparative Example 3 has the following layer weight %: 2 / 18 / 15 / 10 / 10 / 10 / 15 / 10 / 10. Examples 1 and 2 of the present invention have the following layer weight %: 1 / 19 / 15 / 10 / 10 / 10 / 15 / 10 / 10. All films are extruded to have a thickness of 127 microns (or micrometers) before orientation. Examples 1 and 2 of the present invention have a first outer layer thickness of 2 microns or less than 1.27 microns before orientation. Comparative Example 3 has a first outer layer thickness of 2 microns or greater than 2.54 microns before stretching.

[0069] [Table 1]

[0070] All samples are stretched in the machine direction at a ratio of 5.5:1 (MDO inlet at 3.5 m / min versus MDO outlet at 19.2 m / min). No speed reduction is performed during annealing. Each film is stretched with an MDO unit roller (roller preheating temperature is 90-100-105-110°C, stretching temperature is 110°C, annealing is 95°C) to produce an oriented film. The thickness X of the first outer layer before extrusion to a stretch ratio of 5.5 results in a calculated thickness of less than 0.45 microns in the film of the present invention and a calculated thickness of more than 0.45 microns in the comparative film.

[0071] The heat seal strength of the film was measured at a series of sealing temperatures and reported in Table 2 below.

[0072] [Table 2]

[0073] Examples 1 and 2 of the present invention have improved HSIT compared to Comparative Examples 1 to 3. In the examples of the present invention, the HSIT is less than 105°C.

[0074] All documents cited herein, including any cross-referenced or related patents or applications, and any patent applications or patents to which this application claims priority or benefit, are incorporated herein by reference in their entirety unless expressly excluded or otherwise limited. No reference to any document constitutes prior art relating to any invention disclosed or claimed herein, nor does it teach, suggest or disclose such invention, either alone or in any combination with any other reference. Furthermore, if any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in any document incorporated by reference, the meaning or definition assigned to that term in this document shall prevail.

[0075] While specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the appended claims are intended to encompass all such changes and modifications that fall within the scope of the invention.

Claims

1. A process for manufacturing an orientation film, 0.910~0.940g / cm ３ Low-density polyethylene having a density of 105°C or less, and a maximum peak melting temperature (T ｍ To provide an ethylene copolymer having ) A film comprising at least three layers is formed by extruding a first outer layer having a thickness of "X" and containing the low-density polyethylene, an inner layer adjacent to the first outer layer and containing the ethylene copolymer, and a second outer layer. A process comprising oriented the film in at least one direction, wherein the film is oriented with a stretch ratio "Y" and the thickness "X" divided by Y is less than 0.

45.

2. The process according to claim 1, wherein the film is oriented in the direction of the machine.

3. The process according to claim 1, wherein the film is oriented in the transverse direction.

4. The process according to claim 1, wherein the film is oriented in the machine direction with a stretch ratio of 4:1 to 12:1 and in the transverse direction with a stretch ratio of 4:1 to 12:

1.

5. The process according to any one of claims 1 to 4, wherein the first outer layer is less than 2% of the total thickness of the film, and the thickness of the first outer layer is calculated using the formula X divided by Y.

6. The process according to any one of claims 1 to 5, wherein the first outer layer is less than 2% by weight of the film, based on the total weight of the film.

7. The process according to any one of claims 1 to 6, wherein the ethylene copolymer is a polyethylene elastomer / plastomer having a density of less than 0.900 g / cc.

8. The process according to any one of claims 1 to 7, wherein the orientation film comprises at least 95% by weight of the polymer in the orientation film, based on the total weight.

9. The process according to any one of claims 1 to 8, wherein the film has a heat seal initiation temperature of less than 105°C (defined as the seal temperature required to achieve a seal strength of 5 N / 15 mm according to the ASTM F88 method).

10. A process for manufacturing a laminate, A process comprising manufacturing an orientation film according to any one of claims 1 to 9, and bonding the orientation film to a base film with an adhesive.

11. An orientation film, 0.910~0.940g / cm ３ A first outer layer comprising low-density polyethylene having a density of, Adjacent to the first outer layer, with a maximum peak melting temperature (T) of 105°C or lower. ｍ An inner layer containing an ethylene copolymer having ) Including a second outer layer, An orientation film in which the first outer layer has a thickness of less than 0.45 microns.

12. The oriented film according to claim 11, wherein the film is oriented in the mechanical direction, the transverse direction, or both with a combined stretch ratio of at least 2:1 to achieve a calculated thickness of the first outer layer of less than 0.45 microns.

13. The low-density polyethylene has a maximum peak melting temperature of 105°C or higher (T ｍ The orientation film according to claim 11 or 12, having the following characteristics:

14. The orientation film according to any one of claims 11 to 13, wherein the low-density polyethylene is linear low-density polyethylene.

15. The ethylene copolymer has a maximum peak melting temperature (T) of 100°C or less. ｍ An orientation film according to any one of claims 11 to 14, which is a polyethylene elastomer / plastomer having )

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