Polymer film with excellent processability and resistance to harsh conditions.

Abstract

Embodiments of the present disclosure are films comprising at least 95% by weight of an ethylene-based polymer, wherein the ethylene-based polymer is ethylene, C3-C3 14 The film is a polymerization reaction product of α-olefin monomers and optionally polyenes, and the film contains a normalized dart strength (DS) (g / mol) of 400 + 1400 / (MS-2.7) or greater, where the normalized DS is measured in grams (g / mil) according to ASTM 1709 Method A and divided by the film thickness in mills, and MS is the melt strength of the ethylene-based polymer measured in centiNewtons (cN) (Rheotens apparatus, 190°C, 2.4 mm / s2, 120 mm from die exit to wheel center, extrusion speed 38.2 s-1, length 30 mm, diameter 2 mm, and incident angle 180° capillary die), and the MS is at least 4 cN.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims the interests of U.S. Provisional Patent Application No. 63 / 510,763, filed on 28 June 2023, the contents of which are incorporated herein by reference in their entirety.

[0002] (Field of Invention) The embodiments generally relate to ethylene-based polymer films, and more particularly to ethylene-based polymer films having processability and dirt strength. [Background technology]

[0003] Linear low-density polyethylene (LLDPE), produced by solution or gas phase processes, typically possesses excellent mechanical properties but suffers from insufficient melt strength and processability in film manufacturing. Therefore, to increase processability and improve the processability and melt strength of LLDPE resin, some amount of LDPE is typically blended with LLDPE. Unfortunately, the addition of LDPE results in a decrease in the mechanical properties of the resulting blend compared to pure LLDPE resin.

[0004] Therefore, there is a need for an ethylene-based polymer film that has processability and excellent mechanical properties (e.g., dirt resistance) without being blended with LDPE. [Overview of the project]

[0005] This embodiment achieves this need for processability and mechanical strength by including an ethylene-based polymer having at least one polymer fraction within increased long-chain branching. Although not limited by theory, this long-chain branching provides the increased melt strength required for film processing, while the ethylene-based polymer still maintains excellent abrasion resistance properties in the film.

[0006] According to one or more embodiments, a film containing at least 95% by weight of an ethylene-based polymer is provided. The ethylene-based polymer is ethylene, C3-C3 14 The film is a polymerization reaction product of α-olefin monomers and optionally polyenes. The film has a normalized dart strength (DS) of 400 + 1400 / (MS - 2.7) or higher, where normalized DS is measured in grams (g / mil) according to ASTM 1709 Method A and divided by the film thickness in mills, and MS is the melt strength of the ethylene-based polymer measured in centiNewtons (cN) (Rheotens apparatus, 190°C, 2.4 mm / s²). 2 120mm from die exit to wheel center, extrusion speed 38.2s -1 (A capillary die with a length of 30 mm, a diameter of 2 mm, and an incidence angle of 180°), the MS is at least 4 cN.

[0007] These and their embodiments will be described in more detail in the following embodiments for carrying out the invention, in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0008] The following "Modes for Carrying Out the Invention" of specific embodiments of this disclosure can be best understood in conjunction with the following drawings, where similar structures are shown with similar reference numerals.

[0009] The following "Modes for Carrying Out the Invention" of specific embodiments of this disclosure can be best understood in conjunction with the following drawings, where similar structures are shown with similar reference numerals. [Figure 1] The molecular weight distribution of the multi-modal ethylene polymer according to one or more embodiments described herein is graphically illustrated. [Figure 2] The relationship between the melt strength and normalized dirt strength of the multi-modulated ethylene polymers according to one or more embodiments described herein is illustrated graphically. [Modes for carrying out the invention]

[0010] Processes for synthesizing polymers and specific embodiments of polymers synthesized by the processes of this disclosure are described here. It should be understood that the processes for synthesizing polymers of this disclosure may be carried out in different forms and should not be construed as being limited to the specific embodiments described herein. Rather, embodiments are provided so as to ensure that this disclosure is thorough, complete, and fully conveys the scope of the subject matter to those skilled in the art.

[0011] definition The term "polymer" refers to polymer compounds prepared by polymerizing monomers, whether of the same or different types. Therefore, the general term polymer encompasses the term "homopolymer," which is commonly used to refer to polymers prepared from only one type of monomer, and "copolymer," which similarly refers to polymers prepared from two or more different monomers.

[0012] "Polyethylene" or "ethylene-based polymer" means a polymer containing units derived from ethylene monomers at a rate of more than 50% by weight. 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, medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

[0013] The term "LDPE" is also sometimes referred to as "high-pressure ethylene polymer" or "highly branched polyethylene," and is defined as a polymer that 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, which is incorporated herein by reference in its entirety). LDPE resins typically have a viscosity of 0.916 g / cm³. 3 ~0.930g / cm 3 It has a density within the range.

[0014] The term "LLDPE" includes resins produced using the Ziegler-Natta catalyst system, as well as resins produced using single-site catalysts, including but not limited to bismetallocene catalysts (sometimes referred to as "m-LLDPE"), phosphine imines, and geometrically constrained catalysts, and resins produced using post-metallocene molecular catalysts, including but not limited to bis(biphenylphenoxy) catalysts (also referred to as polyvalent aryloxy ether catalysts). LLDPE comprises linear, substantially linear, or heterogeneous ethylene copolymers. LLDPE includes substantially linear ethylene polymers containing fewer long-chain branches than LDPE and further defined in U.S. Patents 5,272,236, 5,278,272, 5,582,923, and 5,733,155, which are incorporated herein by reference in their entirety; uniformly branched linear ethylene polymer compositions such as those in U.S. Patent 3,645,992, which are incorporated herein by reference in their entirety; heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent 4,076,698, which are incorporated herein by reference in their entirety; and blends thereof (such as those disclosed in U.S. Patents 3,914,342 and 5,854,045, which are incorporated herein by reference in their entirety). LLDPE resins can be produced by gas-phase, solution-phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0015] The terms “blend” and “polymer blend” refer to compositions of two or more polymers. Such blends may or may not be miscible. Such blends may or may not be phase-separated. Such blends may or may not contain one or more domain configurations as determined by transmission electron spectroscopy, light scattering, X-ray scattering, and any other method known in the art. A blend is not a laminate, but one or more layers of a laminate may contain a blend. Such blends may be prepared as dry blends and may be formed in situ (e.g., in a reactor), as molten blends, or by other techniques known to those skilled in the art.

[0016] "Multilayer structure" or "multilayer film" means any structure having more than one layer. For example, a multilayer structure (e.g., a film) may have two, three, four, five, six, seven, or more layers. A multilayer structure may be described as having layers specified by letters. For example, a three-layer structure designated as A / B / C may have a core layer (B) and two outer layers (A) and (C).

[0017] As used herein, “multimodal” refers to a polymer produced from multiple polymer fractions, each polymer fraction being produced by a different catalyst in a different reaction environment. Multimodal polymers may include bimodal polymers having two polymer fractions, trimodal ethylene polymers having three polymer fractions, or polymers having three or more polymer fractions.

[0018] As used herein, the term “polyene” refers to a comonomer having at least two double bonds. Polyenes encompass “dienes,” which are comonomers having two double bonds.

[0019] The term "gel" or "gelling" refers to a solid composed of at least two components: first, a three-dimensional crosslinked polymer, and second, a medium in which the polymer does not completely dissolve. If the polymer gels and does not completely dissolve, the reactor may be contaminated with the polymer gel.

[0020] The term "long-chain branching" refers to a branch having more than 100 carbon atoms. "Branching" refers to a portion of a polymer extending from a tertiary or quaternary carbon atom. If a branch extends from a tertiary carbon atom, there are two other branches, which collectively may constitute the polymer strand to which the branch extends. A polymer strand is a linear segment of a polymer, or more specifically, a copolymer, which is optionally joined at its ends by branching junctions. For example, a tetrafunctional branching junction joins the ends of four polymer strands, in contrast to a trifunctional branching junction which joins the ends of three polymer strands.

[0021] The terms “comprising,” “including,” and “having,” and their derivatives, are not intended to exclude the existence 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 include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless otherwise stated. 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.

[0022] Ethylene-based polymers Embodiments of the present disclosure are directed to ethylene-based polymers, and in specific embodiments, to a multimodal ethylene-based polymer comprising first, second, and third polymer fractions. The first, second, and third polymer fractions each comprise a polymerization reaction product of ethylene monomer and optionally a C3-C 14 alpha-olefin comonomer, provided that at least one of the first, second, and third polymer fractions comprises a polymerization reaction product of ethylene monomer, polyene comonomer, and optionally a C3-C 14 alpha-olefin comonomer.

[0023] In one or more embodiments, the polymer may include an acyclic non-conjugated diene. The acyclic non-conjugated diene may include one or more of 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, dimethyldivinylsilane, dimethyldiallylsilane, dimethylallylvinylsilane. The polyene may optionally not include a cyclic or bicyclic polyene, such as a norbornene-based compound, because these cyclic or bicyclic polyenes are not effectively incorporated into the polymer chain to generate long chain branches.

[0024] C3-C 14 The alpha-olefin comonomer may include one or more of 1-propylene, 1-butene, 1-hexene, 1-octene, or a combination thereof.

[0025] As described above, the multimodal ethylene-based polymer of the present invention has excellent processability, which can be partially quantified by its melt strength. Further as described above, this processability and melt strength are due to the long chain branches present in the multimodal ethylene-based polymer. In one or more embodiments, the multimodal ethylene-based polymer may have a melt strength (MS) of 4.0 to 25.0 cN, where MS is the melt strength in cN (Rheotens apparatus, 190 °C, 2.4 mm / s 2120mm from die exit to wheel center, extrusion speed 38.2s -1 (The capillary die has a length of 30 mm, a diameter of 2 mm, and an inlet angle of 180°.) In further embodiments, the melt strength (MS) is 4.0 to 20.0 cN, 4.0 to 15.0 cN, 8.0 to 15.0 cN, or 9.0 to 14.0 cN.

[0026] Furthermore, the trimodal ethylene polymer has a rheological ratio V of 4.0 to 12.0. 0.1 / V 100 It may have V 0.1 V is the viscosity of an ethylene-based polymer at 190°C with an angular frequency of 0.1 radians / second. 100 This is the viscosity of the ethylene-based polymer at 190°C with an angular frequency of 100 radians / second. In further embodiments, the rheological ratio V 0.1 / V 100 The ratio is 4.0 to 8.0, or 4.0 to 6.5. Although not limited to theory, the rheological ratio indicates shear viscosity reduction, and an increase in long-chain branching correlates with an increase in shear viscosity reduction. However, in the present invention, shear viscosity reduction in a trimodal ethylene polymer can be controlled, for example, by generating one or more fractions in the trimodal ethylene polymer in addition to a small amount of long-chain branching.

[0027] Trimodal ethylene polymers may have a melt index (I2) of 0.5–2.0 dg / min or 0.5–1.0 dg / min, where I2 is measured according to ASTM D1238 (2.16 kg / 190°C). Trimodal ethylene polymers may have an I2 of 5.0–15.0 or 5.0–10.0. 10 It may have a / I2 ratio.

[0028] In one or more embodiments, the trimodal ethylene polymer has a density of 0.910 to 0.935 g / cc, 0.910 to 0.920 g / cc, or 0.912 to 0.920 g / cc.

[0029] In one or more embodiments, the trimodal ethylene polymer has a molecular weight distribution (MWD) of 3 to 5, where MWD is defined as Mw / Mn, where Mw is the weight-average molecular weight measured according to conventional gel permeation chromatography, and Mn is the number-average molecular weight. Furthermore, the trimodal ethylene polymer has an Mn of 20.0 to 35.0 kg / mol, or 25.0 to 35.0 kg / mol. Furthermore, the trimodal ethylene polymer has an Mw of 100.0 to 130.0 kg / mol, or 105.0 to 125.0 kg / mol.

[0030] process Various processes and processing parameters are considered suitable for producing the multimodal and trimodal ethylene polymers of this disclosure. In one or more embodiments, the process for producing a multimodal ethylene polymer (e.g., a trimodal ethylene polymer) in a reactor system comprises a first reactor and a second reactor. This method involves ethylene, one or more (C3-C3) 14 The process involves polymerizing an α-olefin monomer and at least one polyene in a first reactor in the presence of one multi-chain catalyst and at least one single-chain catalyst to produce a first reactor polyethylene product containing long-chain branching. The multi-chain catalyst comprises multiple polymerization sites, and the long-chain branching is produced by the cooperative bonding of two polymer chains of the multi-chain catalyst with the polyene during polymerization. In a second reactor, ethylene and one or more (C3-C3) 14 The α-olefin monomer is polymerized in the absence of an initial polyene feed and in the presence of at least one single-chain catalyst to produce a second reactor polyethylene product. The trimodal ethylene polymer comprises the first and second reactor polyethylene products.

[0031] Polymerization reactions are intended to include solution polymerization, slurry polymerization, or gas-phase polymerization. In specific embodiments, solution polymerization is carried out in a first reactor, a second reactor, or both. The first and second reactors may be in parallel or in series. Such a solution polymerization process may involve using, for example, one or more conventional reactors, such as loop reactors, isothermal reactors, adiabatic reactors, fluidized bed gas-phase reactors, stirred tank reactors, and batch reactors, for example, in parallel, in series, or in any combination thereof.

[0032] Exemplary solvents used in solution polymerization processes include, but are not limited to, isoparaffins. For example, such solvents are commercially available from ExxonMobil Chemical under the name ISOPAR(trademark)E.

[0033] As described above, one or more single-chain catalysts may be present in the first reactor and the second reactor. In one embodiment, both the first reactor and the single-chain catalyst may contain one single-chain catalyst.

[0034] As used herein, a “single-chain catalyst,” also known as a single-site catalyst, is a polymerization catalyst having one active polymerization site and / or a reactive metal center. A variety of single-chain catalysts are considered suitable. These may include, but are not limited to, bis-metallocene catalysts, phosphine imines, constrained geometric catalysts, post-metallocene catalysts, and single-site molecular catalysts, and may also include bis(biphenylphenoxy) catalysts (also known as polyvalent aryloxy ether catalysts).

[0035] In one embodiment, the single-chain catalyst in the first reactor, the second reactor, or both comprises a bis(biphenylphenoxy) catalyst. According to some embodiments, the bis(phenylphenoxy) catalyst has a structure according to formula (I).

[0036] [ka]

[0037] In formula (I), M is a metal selected from titanium, zirconium, or hafnium, and the metal is in a formal oxidation state of +2, +3, or +4. (X) n The subscript n is 0, 1, or 2. If the subscript n is 1, X is a monocephalic or bisephalic ligand, and if the subscript n is 2, each X is selected from monocephalic ligands. Each Z is independently -O-, -S-, -N(R N )-, or -P(R P )- Selected from, R 1 and R 16 These are independently -H, (C1~C 40 )-hydrocarbyl, (C1~C 40 ) Heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -OR C , -SR C -NO2, -CN, -CF3, R C S(O)-, R C S(O)²⁻, -N=C(R) C )2, R C C(O)O-, R C OC(O)-, R C C(O)N(R)-, (R C ) Selected from the group consisting of 2NC(O)-, halogens, radicals having formula (II), radicals having formula (III), and radicals having formula (IV).

[0038] [ka]

[0039] In equations (II), (III), and (IV), R 31~35 , R 41~48 , and R 51~59 Each of these is independent of -H, (C1~C 40 ) Hydrocarbyl, (C1~C 40 ) Heterohydrocarbyl, -Si(R C )3, -Ge(R C)3, -P(R P )2, -N(R N )2, -OR C , -SR C -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R C ) Selected from 2NC(O)-, or halogen, however, R 1 or R 16 At least one of them is a radical having formula (II), a radical having formula (III), or a radical having formula (IV).

[0040] In one or more embodiments, each X is independent of any other ligand X, and is halogen, unsubstituted (C1~C 20 ) Hydrocarbyl, unsubstituted (C1~C 20 ) Hydrocarbyl C(O)O-, or R K R L It can be a monodentate ligand of N-, in the formula R K and R L Each of these is independent of the non-substitutable (C1~C 20 ) It is hydrocarbyl.

[0041] Further details and examples of bis(biphenylphenoxy) catalysts are provided in International Publication Nos. WO2011 / 146291, WO2018 / 183056, WO2019 / 190925 and U.S. Patent No. 7060848(B2), which are incorporated herein by reference in their entirety.

[0042] In one embodiment, the single-chain catalyst in the first reactor, the second reactor, or both may include a phosphineimine catalyst. The phosphineimine pro catalyst may have the structure of formula (V).

[0043] [ka]

[0044] In formula (V), each Q is independently (C1-C 50 ) hydrocarbyl, (C1-C 50 ) heterohydrocarbyl, -CH2Si(R C ) 3-Q (OR C ) Q , -Si(R C ) 3-J (OR C ) J , -OSi(R C ) 3-J (OR C ) J , -CH2Ge(R C ) 3-J (OR C ) J , -Ge(R C ) 3-J (OR C ) J , -P(R C ) 2-W (OR C ) W , -P(O)(R C ) 2-W (OR C ) W , -N(R C )2, -NH(R C ), -N(Si(R C )3)2, -NR C Si(R C )3, -NHSi(R C )3, -OR C , -SR C , -NO2, -CN, -CF3, -OCF3, -S(O)R C , -S(O)2R C , -OS(O)2R C , -N=C(R C )2, -N=CH(R C ), -N=CH2, -N=P(R C )3, -OC(O)R C , -C(O)OR C , -N(R C )C(O)R C , -N(R C)C(O)H, -NHC(O)R C ,-C(O)N(R C )2, -C(O)NHR C -C(O)NH2, halogen, B(R Y )4, Al(R Y )4, or Ga(R Y )4, or a monodentate ligand selected from hydrogen, and each R C (C1~C 30 ) Hydrocarbyl, or (C1~C 30 ) is a heterohydrocarbyl, where each J is 0, 1, 2, or 3, each W is 0, 1, or 2, and each R Y is -H, (C1-C 30 ) A hydrocarbyl or halogen atom, and two X ligands can be bonded to form a metallacycle ring.

[0045] In formula (V), each Y is independently a Lewis base, and Q and Y can optionally be linked to form a ring. Each subscript m is 1 or 2, and each subscript n is 0, 1, and 2. The metal-ligand complex is charge-neutral overall.

[0046] In formula (V), M2 is titanium, zirconium, or hafnium, and R 60 , R 61 , R 62 , R 63 , and R 64 (C1~C 50 ) Hydrocarbyl, (C1~C 50 ) is a heterohydrocarbyl, R 61 , R 62 , R 63 , and R 64 Any of these can be optionally bonded to form a ring structure, R 65 , R 66 , and R 67 (C1~C 20 ) Hydrocarbyl, (C1~C 20 ) Heterohydrocarbyl, (C6~C 30 )aryl, (C5~C 30 ) is a heteroaryl, R65 , R 66 , and R 67 Two of them are optionally joined to form a ring.

[0047] In various embodiments, in formula (V), (A)R 60 and R 61 They are joined together to form a ring, and one or more R S It is optionally replaced by (B)R 52 and R 63 They are joined together to form a ring, and one or more R S It is either optionally substituted by (C), or both (A) and (B). Therefore, when (A), (B), or (C) occurs, the cyclopentadienyl of formula (V) has a structure selected from the group consisting of:

[0048] [ka]

[0049] As described above, polychain catalysts produce polymer fractions having long-chain branching. A polychain catalyst is a metal-ligand catalyst having at least two polymerization sites, which promote the growth of at least two distinct polymer chains. Suitable polychain catalysts and their mechanisms of action are described in International Publications WO2020 / 069364, 2020 / 205585, and 2021195502(A1), which are incorporated herein by reference in their entirety and briefly summarized here. At high levels, long-chain branching fractions are produced by the addition of polyenes, specifically acyclic non-conjugated dienes, in the presence of a polychain catalyst. The polyene is added to the polymer chain in a similar manner to α-olefins, but leaving behind a pendant vinyl group, which can be reinserted into the polymer chain to create long-chain branching. As described above, a polychain catalyst that grows two distinct polymer chains has at least two polymer chain sites. One alkene of the polyene is incorporated into one polymer chain, and due to the proximity of the growth sites, a second alkene of the polyene is then rapidly incorporated into a second polymer chain, thereby forming a bridge or lung. This sequential addition of the diene is called the “cooperative” addition of the polyene and is distinguished from catalysts that do not have two proximal chains, where the addition of the polyene results in the concentration of the vinyl-containing polymer that reacts later in the reactor. The cooperative addition of the polyene is called the “ladder” mechanism. The term “lung” refers to the diene that, once incorporated into two separate polymer strands, thereby linking the strands together. The first and second polymer strands can continue to grow until the polymer is released from the catalyst, the catalyst dies, or another diene is added.

[0050] Embodiments of this disclosure utilize a minimal amount of multi-chain and single-chain catalysts in a first reactor. While not theoretically bound, single-chain catalysts polymerize ethylene and optionally alpha-olefin comonomers, but specifically, they do not create long-chain branching with a significant amount of polyene because they do not produce two adjacent polymer chains in which polyene is incorporated. Thus, single-chain catalysts produce a polymer fraction substantially free of long-chain branching, while multi-chain catalysts produce a long-chain branched polymer fraction in the same reactor without gel formation and reactor contamination. Therefore, the polyethylene product of the first reactor comprises a first fraction having long-chain branching and a second fraction substantially free of long-chain branching. As used herein, “substantially free of long-chain branching” means less than 0.01 long-chain branches per 1000 carbon atoms (LCB / 1000C) as measured by NMR. In the following embodiments, the first reactor is called a high-density reactor because the first reactor polyethylene product may have a density greater than 0.930 g / cc and a melt index (I2) greater than 3 dg / min. In one or more embodiments, a trimodal ethylene polymer constitutes 35 to 55% by weight of the first reactor polyethylene product, which includes a first fraction and a second fraction.

[0051] In one or more embodiments, the first fraction, i.e., the long-chain branched fraction, may account for about 2 to 10% by weight of the multimodal ethylene polymer (e.g., trimodal ethylene polymer).

[0052] A second reactor, which does not contain an initial polyene feed and also does not contain a multi-chain catalyst, produces a second reactor polyethylene product that is substantially free of long-chain branching. In this case, the single-chain catalyst in the second reactor will polymerize ethylene and optionally alpha-olefin comonomers. In one or more embodiments, a trimodal ethylene polymer constitutes 45-65% by weight of the second reactor polyethylene product, including at least a third polymer fraction. In the following embodiments, the second reactor is called a low-density reactor because the second reactor polyethylene product may have a density of less than 0.910 g / cc, a melt index (I2) of less than 0.8 dg / min, and a MWD of less than 3.0. For a trimodal ethylene polymer, the combination of a first reactor (high-density reactor) polyethylene product having a first and second fraction with long-chain branching and a second reactor (low-density reactor) having a third fraction polyethylene product results in a molecular weight distribution as depicted in Figure 1.

[0053] film Additional embodiments of the present disclosure relate to films. In some embodiments, the film may include a multimodal or trimodal ethylene polymer as described above.

[0054] In other embodiments, the film is made of ethylene, C3-C3 14 The ethylene polymer may include α-olefin monomers and optionally polyene polymerization reaction products. In embodiments, this ethylene polymer may be multimodal and / or trimodal. In additional embodiments, the ethylene polymer of the film may be ethylene, C3-C3 14 The film may contain α-olefin monomers and polymerization reaction products of polyenes. In specific embodiments, the film may contain at least 95% by weight of an ethylene-based polymer, at least 97% by weight of an ethylene-based polymer, at least 99% by weight of an ethylene-based polymer, or at least 99.5% by weight of an ethylene-based polymer. In further embodiments, the film may contain substantially no other polymer components.

[0055] For these film embodiments, the film may have a normalized dart strength (DS) (g / mill) of 400 + 1400 / (MS-2.7) or higher, where the normalized DS is measured in grams (g) according to ASTM 1709 Method A and divided by the film thickness in mills, provided that the melt strength (MS) is at least 4 cN. This relationship between normalized dart strength and melt strength is illustrated in Figure 2. By simultaneously achieving higher normalized dart strength and melt strength, the film does not sacrifice the abrasion resistance to processability, which is a trade-off of LLDPE / LDPE blends. In further embodiments also illustrated in Figure 2, the normalized DS in g / mills is 430 + 2000 / (MS-2.4) or higher, 400 + 2736 / (MS-2.2) or higher, or 390 + 3900 / (MS-2.5) or higher. Furthermore, the normalized DS of the film may be 750-1750 g / mil or 750-1500 g / mil.

[0056] The film may include a single-layer film or a multilayer film. The films of this disclosure may have a variety of thicknesses. The thickness of the film may depend on a number of factors, including, for example, the number of layers in the film, the composition of the layers in a multilayer film, the desired properties of the film, the desired end use of the film, and the manufacturing process of the film. In embodiments, the film may have a thickness of 0.5 to 5 mils, 1 to 4 mils, or 1.5 to 2.5 mils.

[0057] Various methodologies are contemplated for producing the films of this disclosure. In one or more embodiments, the process for producing the film may include extrusion of a cast film or extrusion of an inflated film.

[0058] additives The above-mentioned multimodal ethylene polymers, trimodal ethylene polymers, or films produced therefrom may further contain one or more additives known to those skilled in the art, such as plasticizers, stabilizers including viscosity stabilizers, hydrolysis stabilizers, primary and secondary antioxidants, UV absorbers, antistatic agents, dyes, pigments, or other colorants, inorganic fillers, flame retardants, lubricants, reinforcing agents such as glass fibers and flakes, synthetic (e.g., aramid) fibers or pulp, forming agents or foaming agents, processing aids, slip additives, anti-tack agents such as silica or talc, release agents, tackifying resins, or two or more combinations thereof. Inorganic fillers such as calcium carbonate may also be incorporated into the film.

[0059] Goods Embodiments of this disclosure also relate to articles such as packages formed from the films of this disclosure. The films of this disclosure are particularly useful in articles where good tear strength and dirt strength are desired. Examples of such articles include flexible packages, pouches, self-standing pouches, and ready-made packages or ready-made pouches. Various methods for manufacturing embodiments of articles from the films disclosed herein will be well known to those skilled in the art.

[0060] Test method The test method includes the following:

[0061] Melt Index Melt indices I2 and I of polymer samples 10 These were measured at 190°C and under loads of 2.16 kg and 10 kg, respectively, according to ASTM D-1238 (Method B).

[0062] density Samples for density measurement were prepared according to ASTM D4703. Within one hour of sample pressurization, measurements were performed according to ASTM D792, Method B.

[0063] ASTM D1709 Dirt Drop The film dart drop test determines the energy required to break a plastic film under specified conditions of impact from a free-falling dart. The test result is expressed as the energy of the impactor falling from a specified height that would cause 50% of the test specimen to break.

[0064] After the film is produced, it is acclimatized for at least 40 hours at 23°C (±2°C) and 50% RH (±5) according to ASTM standards. The standard test conditions are 23°C (±2°C) and 50% RH (±5) according to ASTM standards.

[0065] Test results are reported by Method A, which uses a 1.5-inch diameter dart head and a drop height of 26 inches. The thickness of the sample is measured at the center of the sample, and the sample is then secured in an annular specimen holder with an inner diameter of 5 inches. The dart is loaded above the center of the sample and released by either a pneumatic or electromagnetic mechanism.

[0066] The test is conducted according to the "staircase" method. If a sample is damaged, a new sample is tested with the dart weight reduced by a known fixed amount. If a sample is not damaged, a new sample is tested with the dart weight increased by a known amount. After 20 test specimens have been tested, the number of damaged specimens is determined. If this number is 10, the test is completed. If this number is less than 10, the test is continued until 10 damages are recorded. If this number is greater than 10, the test is continued until the total number of undamaged specimens is 10. The dart drop strength is determined from these data according to ASTM D1709 and expressed in grams as a Type A dart drop impact. All samples analyzed were 2 mils thick.

[0067] Instrumented Dirt Impact The instrumented dirt impact method is performed on plastic film test specimens using an Instron CEAST9350 impact tester, in accordance with ASTM D7192. The test is conducted using a 12.7 mm diameter tap with a hemispherical head and a 75 mm diameter clamp assembly with a rubber grip. The instrument is equipped with an environmental chamber for testing at low or high temperatures. Typical specimen size is 125 mm × 125 mm. The standard test speed is 200 m / min.

[0068] Gel Penetration Chromatography (GPC) Size Exclusion Chromatography (SEC) (Conventional GPC) GPC-SEC (conventional GPC) measurements were performed according to the test procedures defined in International Publication No. WO2021195502(A1).

[0069] Triple Detector GPC (TD) (Absolute GPC) GPC-TD (absolute GPC) measurements were performed according to the test procedures defined in International Publication No. WO2021195502(A1).

[0070] MD tearing MD tear was measured according to ASTM D-1922. The force (grams) required to propagate the tear across the film specimen was measured using an Elmendorf Tear tester. Acting on by gravity, the pendulum oscillates in an arc, tearing the specimen through a pre-cut slit. The tear propagates transversely. The specimen was acclimatized at the pre-test temperature for a minimum of 40 hours.

[0071] Dynamic rheological analysis To characterize the rheological behavior of substantially linear ethylene polymers, S. Lai and G.W. Knight (ANTEC'93 Proceedings, Insite™ Technology Polyolefins (ITP) - New Rules in the Structure / Rheology Relationship of Ethylene α-Olefin Copolymers, New Orleans, La., May 1993) introduced the Dow Rheology Index (DRI), a novel rheological measure representing the "normalized relaxation time as a result of long-chain branching" of the polymer. S. Lai et al. (ANTEC'94, Dow Rheology Index (DRI) for Insite™ Technology Polyolefins (ITP): Unique Structure-Processing Relationships, pp. 1814-1815) defined the DRI as the degree to which the rheology of known ethylene-octene copolymers, known as ITPs (Dow's Insite Technology Polyolefins) that incorporate long-chain branching into their polymer backbone, deviates from the rheology of conventional linear homogeneous polyolefins that are reported to lack long-chain branching (LCB) according to the following normalized equation: DRI=[3650000×(τ0 / η0)-1] / 10 (Equation 1) (wherein τ0 is the characteristic relaxation time of the material and the zero shear rate complex viscosity of the material). DRI is given by the following generalized Cross formula, as described in U.S. Patent No. 6,114,486, i.e., η * (ω)=η0 / [1+(ω·τ0)] n ] (Equation 2) (In the formula, n is the power law exponent of the material, η) * (ω) and ω are the measured complex viscosity and applied frequency data, respectively) Least squares fitting of the rheology curve (dynamic complex viscosity η) * (ω) is calculated by the ratio of the applicable frequency (ω), for example, 0.01 to 100 rads / sec.

[0072] Dynamic rheological measurements are performed in dynamic mode under an inert atmosphere, according to ASTM D4440, using a dynamic rheometer (e.g., TA Instruments' ARES rheometer) with a 25 mm diameter parallel plate. For all experiments, the rheometer is thermally stabilized at 190°C for at least 30 minutes before inserting the properly stabilized, compression-molded sample (with antioxidant additives) onto the parallel plate. The plate is then closed with a positive normal force registered in the meter to ensure good contact. After about 5 minutes at 190°C, the plate is lightly compressed to trim any excess polymer around the plate. A further 10 minutes is required for thermal stability and normal force to return to zero. In other words, all measurements are performed after equilibrating the sample at 190°C for about 15 minutes, under a complete nitrogen blanket.

[0073] Two strain sweep (SS) experiments are first performed at 190°C to determine the linear viscoelastic strain that produces a torque signal exceeding 10% of the lower scale of the transducer across the entire frequency range (e.g., 0.01–100 rad / sec). The first SS experiment is performed at a low application frequency of 0.1 rad / sec. This test is used to determine the sensitivity of the torque at low frequencies. The second SS experiment is performed at a high application frequency of 100 rad / sec. This is to ensure that the selected application strain falls well within the linear viscoelastic region of the polymer so that vibrational rheology measurements do not induce structural changes in the polymer during the test. Furthermore, a time sweep (TS) experiment is performed at a low application frequency of 0.1 rad / sec with the selected strain (determined by the SS experiment) to check the stability of the sample during the test.

[0074] Storage modulus (or modulus of elasticity), loss modulus (or viscous modulus) (G''), complex modulus (G'') * ), complex viscosity (η * ), and tanδ (ratio of loss modulus to storage modulus, G'VG') were obtained as a function of frequency (ω) at a given temperature (e.g., 190°C).

[0075] ASTM D1922 MD (machine direction) and CD (transverse direction) Elmendorf tear type B The Elmendorf tear test uses an Elmendorf tear testing machine to determine the average force required to propagate a tear through a specified length of plastic film or non-rigid sheet after the start of tearing.

[0076] After manufacturing films from the samples to be tested, the films were acclimatized for at least 40 hours at 23°C (±2°C) and 50% relative humidity (±5) according to ASTM standards. The standard test conditions were 23°C (±2°C) and 50% relative humidity (±5) according to ASTM standards.

[0077] The force required in grams to propagate a tear in a film or sheet specimen was measured using a precisely calibrated pendulum device. In the test, gravity acted upon the pendulum, causing it to swing in an arc and tear the specimen through a pre-cut slit. The specimen was held at one end by the pendulum and at the other by a fixed member. Energy loss due to the pendulum was indicated by a pointer or electronic scale. The scale reading was a function of the force required to tear the specimen.

[0078] The sample specimens used in the Elmendorf tear test were of a "constant radius shape" as specified in ASTM D1922. The test was typically performed on specimens cut from both the MD and CD directions of the film. Before testing, the thickness of the film specimen was measured at the center of the sample. A total of 15 specimens were tested for each film direction, and the average tear strength and average thickness were reported. The average tear strength was normalized against the average thickness. [Examples]

[0079] The following examples illustrate the features of the present disclosure, but are not intended to limit the scope of the present disclosure. The performance of embodiments of the multilayer films described herein was analyzed in the following experiments.

[0080] Polymer synthesis The trimodal ethylene polymers 1 to 11 of the present invention, produced by a double reactor having a multi-chain catalyst and two single-chain catalysts, were prepared by the method described below. Comparative Example C1 was a bimodal ethylene polymer produced in a double reactor system having single-chain catalysts in each reactor but no multi-chain catalyst. Comparative Example C2 was a bimodal ethylene polymer produced in a single reactor system having a single-chain catalyst and a multi-chain catalyst. Comparative Example C3 was a monomodal ethylene polymer produced in a single reactor system having a single-chain catalyst.

[0081] Before introducing them into the reaction environment, all raw materials (monomers and comonomers) and process solvent (high-purity isoparaffin solvent with a narrow boiling point range, ISOPAR-E) were purified using molecular sieves. Hydrogen was supplied under pressure as a high-purity grade and no further purification was performed. The reactor monomer feed stream was pressurized to a pressure exceeding the reaction pressure via a mechanical compressor. The solvent and comonomer feed streams were also pressurized to a pressure exceeding the reaction pressure using pumps. Individual catalyst components were manually batch diluted with purified solvents and pressurized to a pressure exceeding the above reaction pressure. All reaction feed streams were measured with mass flow meters and independently controlled by a computer-controlled automatic valve control system.

[0082] Two reactor systems were used in a parallel configuration. Each continuous solution polymerization reactor consisted of a non-adiabatic, isothermal, continuously stirred tank reactor (CSTR) filled with liquid to remove heat. Independent control of all fresh solvents, monomers, comonomers, dienes, hydrogen, and catalyst components was possible. All fresh feed streams to each reactor (solvent, monomers, comonomers, dienes, and hydrogen) were temperature-controlled to maintain a single solution phase by passing the feed streams through a heat exchanger. Catalyst components were injected directly into the polymerization reactors. The supply of the main catalyst component was computer-controlled to maintain monomer conversion in each reactor at a specified target. Co-catalyst components were supplied based on a calculated, specified molar ratio to the main catalyst component. Reactor feeds are shown in Tables 1A and 1B. Immediately after the injection point of the reactor feeds, the feed streams were mixed with the contents of a circulating polymerization reactor with a static mixing element. The reactors had oil jackets around them, which played a role in maintaining an isothermal reaction environment at a specified temperature.

[0083] In the double series reactor configuration, the effluent from each polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst components, and polymer) was exited through the appropriate reactor and blended. The contents were deactivated by the addition of isopropanol. Other additives were added at this same reactor outlet to stabilize the polymer (typical antioxidants suitable for stabilization during extrusion and film processing).

[0084] Following catalyst deactivation and additive addition, the reactor effluent entered a devolving system where the polymer was removed from the non-polymer stream. The isolated polymer molten material was pelletized and collected. Recycling was not performed in this process, but it is generally possible to recycle such materials.

[0085] [Table 1-1]

[0086] [Table 1-2]

[0087] [Table 2-1]

[0088] [Table 2-2]

[0089] Co-catalyst A (CoCat A is bis(talualkyl hydride)methylammonium tetrakis(pentafluorophenyl) borate)

[0090] Co-catalyst B (CoCat B) is MMAO-3A or modified methylaluminoxane.

[0091] The structures of CAT A, CAT B, and CAT C, as described in Tables 1A and 1B, are provided in Table 2 below.

[0092] [Table 3]

[0093] Film processing Films were tested using Examples 1-11 of the present invention, Comparative Example C1, and commercially available resins and blends C4-C7.

[0094] C4 contained 80% by weight of C1 and 20% by weight of AGILITY® 1021. AGILITY® 1021, commercially available from Dow Inc. (Midland MI), is an LDPE resin with a density of 0.919 g / cc and a melt index (I2) of 1.9 dg / min.

[0095] C5 constitutes 100% by weight of a comparatively bimodal polyethylene resin having a density of 0.918 g / cc and a melt index (I2) of 0.85 dg / min. The comparatively bimodal polyethylene resin was produced according to the method of Invention Example 1 of International Publication No. WO2015200742, which is incorporated herein by reference.

[0096] C6 contained 90% by weight of C5 and 10% by weight of AGILITY® 1021.

[0097] C7 contained 80% by weight of C5 and 20% by weight of AGILITY® 1021.

[0098] Specifically, a 2-mil inflation film was fabricated using a single-layer Dr. Collin inflation film line. This line was equipped with a grooved feed zone and a 30:1 L / D single-screw extruder with a 30 mm screw diameter. The annular die had a diameter of 60 mm and used a double-lip air-ring cooling system. The die lip gap was 2 mm and the blow-up ratio (BUR) was 2.0. The flattening width was approximately 48 cm. The frost line height was 5-6 inches. The total discharge rate was 5-8 kg / hour. The melting temperature was 200-220°C and the die temperature was set to 225°C.

[0099] Film and polymer data

[0100] [Table 4-1]

[0101] [Table 4-2]

[0102] [Table 5-1]

[0103] [Table 5-2]

[0104] [Table 6]

[0105] As shown in Tables 3A-3C, Samples 1-11 of the present invention had melt strengths in the range of 4.7-13.3 cN and normalized dart A values ​​of 760-1373 g / mil. These normalized dart A values ​​are significantly higher than those of C4, C6, and C7 blends containing LDPE to increase melt strength, as well as C5 single resin films. This demonstrates how LDPE increases melt strength and processability, but comes at the trade-off of significantly reducing abuse resistance, i.e., normalized dart A.

[0106] Furthermore, as shown in Comparative Example C1, which does not contain a multi-chain catalyst or diene, the melt strength was lower (3.2 cN) due to the lack of long-chain branching. Moreover, the bimodal polymer from the first reactor (Comparative Example C2), although it has long-chain branching, fails to achieve the melt strength (2.2 cN) of the polymer of the present invention due to its high melt index (I2) of 29.5 dg / min. Finally, the unimodal Comparative Example C3, which essentially does not contain long-chain branching, has a melt strength of 4.5 cN, which is achieved by having a very low melt index (I2) of 0.26 dg / min.

[0107] While the subject matter of this disclosure has been described in detail and with reference to specific embodiments, it should be noted that the various details disclosed herein should not be construed as relating to elements that are essential components of the various embodiments described herein. Furthermore, it will be apparent that modifications and variations are possible without departing from the scope of this disclosure, including but not limited to the embodiments defined in the appended claims.

Claims

1. A film containing at least 95% by weight of an ethylene-based polymer, The ethylene-based polymer is composed of ethylene, C ３ ~C １４ The polymerization reaction product of α-olefin monomers and optionally polyenes, and The film contains a normalized dart strength (DS) (g / mil) of 400 + 1400 / (MS - 2.7) or greater, where the normalized DS is the dart strength measured in grams (g) according to ASTM 1709 Method A, divided by the film thickness in mills, and MS is the melt strength of the ethylene polymer measured in centiNewtons (cN) (Rheotens apparatus, 190°C, 2.4 mm / s). ２ 120 mm from die exit to wheel center, extrusion speed 38.2 s －１ A film having a capillary die with a length of 30 mm, a diameter of 2 mm, and an incident angle of 180°, wherein the MS is at least 4 cN.

2. The film according to claim 1, wherein the film substantially contains no other polymer components.

3. The film according to claim 1 or 2, wherein the film is a single-layer or multi-layer film.

4. The ethylene-based polymer is composed of ethylene, C ３ ~C １２ A film according to any one of claims 1 to 3, which is a polymerization reaction product of α-olefin and polyene.

5. The ethylene polymer has a rheology ratio V of 4.0 to 12 ０．１ / V １００ where V ０．１ is the viscosity of the ethylene polymer at 190 °C at an angular frequency of 0.1 radian per second, and V １００ is the viscosity of the ethylene polymer at 190 °C at an angular frequency of 100 radians per second. The film according to any one of claims 1 to 4

6. The aforementioned rheological ratio V ０．１ / V １００ The film according to claim 5, wherein the coefficient is 4.0 to 8.

0.

7. When the ethylene-based polymer was measured according to ASTM D1238 (2.16 kg / 190°C), it was found to be 0.5 to 2.0 dg / min. ２ A film according to any one of claims 1 to 6, having the following characteristics.

8. The film according to any one of claims 1 to 7, wherein the ethylene-based polymer has a density of 0.910 to 0.935 g / cc.

9. The film according to any one of claims 1 to 8, wherein the ethylene polymer is a multimodal polymer.

10. The ethylene-based polymer has an MWD of 3.0 to 5.0, and the MWD is M ｗ / M ｎ Defined as, M ｗ However, this is the weight-average molecular weight measured according to conventional gel permeation chromatography, M ｎ The film according to any one of claims 1 to 9, wherein the molecular weight is a number-average molecular weight.

11. The film according to any one of claims 1 to 10, wherein the melt strength (MS) is 4.0 to 25 cN or 8.0 to 15 cN.

12. The film according to any one of claims 1 to 11, wherein the normalized DS of the film is 750 to 1750 g / mil.

13. The film according to any one of claims 1 to 12, wherein the normalized DS in g / mil units is 430 + 2000 / (MS - 2.4) or greater.

14. The film according to any one of claims 1 to 13, wherein the normalized DS in g / mil units is 400 + 2736 / (MS - 2.2) or greater.

15. The film according to any one of claims 1 to 14, wherein the normalized DS in g / mil units is 390 + 3900 / (MS - 2.5) or greater.

16. The film according to any one of claims 1 to 15, wherein the film has an average thickness of 1.0 to 3.0 mils.

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