Bimodal ethylene-based polymers

Abstract

According to embodiments of the present disclosure, a bimodal ethylene-based polymer may be the polymerized reaction product of ethylene and one or more C3-C14 olefinic comonomers, wherein the bimodal ethylene-based polymer comprises: a high density fraction (HDF) from 12.0% to 35.0%, the HDF being defined as a ratio of the mass eluted at temperatures from 93 °C to 119 °C to the total mass eluted when measured using an improved comonomer content distribution (iCCD) curve of mass eluted versus temperature; an I10 / I2 ratio from 5.5 to 7.0, wherein I2 is the melt index when measured according to ASTM D 1238 at a load of 2.16 kg and temperature of 190° C. and I10 is the melt index when measured according to ASTM D 1238 at a load of 10 kg and temperature of 190° C; and the high density fraction has a molecular weight (Mw) of less than 120,000 g / mol.

Description

BIMODAL ETHYLENE-BASED POLYMERSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 639,180 filed April 26, 2024, the contents of which are incorporated in their entirety herein.BACKGROUNDTechnical Field

[0002] Embodiments of the present disclosure generally relate to ethylene-based polymers, and more specifically to bimodal ethylene-based polymers.Technical Background

[0003] Processability and dart impact performance are significant factors to consider when manufacturing polyethylene film. Processability (usually quantified by I10 / I2 ratio) refers to the ease with which a film can be produced using a particular manufacturing process. Polyethylene films are often produced by extrusion. The processability of the polymer is important to achieve consistent and high-quality films. Dart impact refers to the impact performance of a film. Dart drop tests provide a quantitative measure of the film’s ability to withstand impact loading. Dart impact is of particular importance for polyethylene films because polyethylene films are often subjected to impact loading during consumer use. For example, polyethylene films used in packaging may be dropped or handled roughly during transportation or storage.

[0004] Generally, processability and dart impact strength are inversely correlated. It is important for producers to balance processability and dart impact to produce quality films at acceptable rates which are capable of meeting dart impact specifications.BRIEF SUMMARY

[0005] Accordingly, there is a need for linear low density polyethylenes with improved processability characteristics that can still meet dart impact performance standards.Embodiments of the present disclosure meet this need by providing a bimodal ethylene-based polymer with a high density fraction (HDF) from 12.0% to 35.0%, where the high density fraction has a molecular weight (Mw) of less than 120,000 g / mol. Without being limited by theory, it is believed that bimodal ethylene-based polymers with a high density fraction (HDF) from 12.0% to 35.0% and a molecular weight distribution skewed towards lower molecular weights (such as less than 120,000 g / mol) have relatively broad molecular weight distributions and relatively great amounts of long chain branching, which leads to both improved dart performance and processability.

[0006] Embodiments of the present disclosure, include a bimodal ethylene-based polymer, the bimodal ethylene-based polymer being the polymerized reaction product of ethylene and one or more C3-C14 olefinic comonomers. The bimodal ethylene-based polymer comprises: a high density fraction (HDF) from 12.0% to 35.0%, the HDF being defined as a ratio of the mass eluted at temperatures from 93 °C to 119 °C to the total mass eluted when measured using an improved comonomer content distribution (iCCD) curve of mass eluted versus temperature; an I10 / I2 ratio from 5.5 to 7.0, wherein I2 is the melt index when measured according to ASTM D 1238 at a load of 2.16 kg and temperature of 190° C. and I10 is the melt index when measured according to ASTM D 1238 at a load of 10 kg and temperature of 190° C; and the high density fraction has a molecular weight (Mw) of less than 120,000 g / mol.

[0007] These and other embodiments are described in more detail in the Detailed Description. It is to be understood that both the foregoing general description and the following detailed description present embodiments of the presently disclosed technology, and are intended to provide an overview or framework for understanding the nature and character of the technology as it is claimed.DETAIEED DESCRIPTION

[0008] Definitions

[0009] The term “polymer” refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term “homopolymer,” usually employed to refer to polymers prepared from only one typeof monomer as well as “copolymer” which refers to polymers prepared from two or more different monomer types.

[0010] “Polyethylene” or “ethylene-based polymer” shall mean polymers comprising greater than 50% by weight of units that have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more monomer types). 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 catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m-LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).

[0011] The term “LDPE” may also be referred to as “high pressure ethylene polymer” or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homopolymerized or copolymerized in autoclave or tubular reactors at pressures above 14,500 psi (100 MPa) with the use of free-radical initiators, such as peroxides (see, for example, U.S. Patent No. 4,599,392, which is hereby incorporated by reference in its entirety). LDPE resins typically have a density in the range of 0.916 g / cm3to 0.930 g / cm3.

[0012] The term “LLDPE,” includes resin made using Ziegler-Natta catalyst systems as well as resin made using single-site catalysts, including, but not limited to, bis-metallocene catalysts (sometimes referred to as “m-LLDPE”), phosphinimine, and constrained geometry catalysts, and resins made using post-metallocene, molecular catalysts, including, but not limited to, bis(biphenylphenoxy) catalysts (also referred to as polyvalent aryloxyether catalysts). LLDPE includes linear, substantially linear, or heterogeneous ethylene-based copolymers. LLDPEs contain less long chain branching than LDPEs and include the substantially linear ethylene polymers, which are 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 each of which are incorporated herein by reference in their entirety; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992 which is incorporated herein by reference in its entirety; the heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S.Patent No. 4,076,698 which is incorporated herein by reference in its entirety; and blends thereof such as those disclosed in U.S. Patent No. 3,914,342 and U.S. Patent No. 5,854,045 which are incorporated herein by reference in their entirety. The LLDPE resins 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] “Blend,” “polymer blend,” and like terms mean a composition of two or more polymers. Such a blend may or may not be miscible. Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and any other method known in the art. Blends are not laminates, but one or more layers of a laminate may contain a blend. Such blends can be prepared as dry blends, formed in situ (e.g. , in a reactor), melt blends, or using other techniques known to those of skill in the art.

[0014] “Multilayer structure” or “multilayer film” means any structure having more than one layer. For example, the multilayer structure (for example, a film) may have two, three, four, five, six, seven, or more layers. A multilayer structure may be described as having the layers designated with letters. For example, a three-layer structure designated as A / B / C may have a core layer, (B), and two external layers, (A) and (C).

[0015] As used herein, “bimodal” refers to polymers produced from two polymer fractions, each polymer fraction being produced by a distinct catalyst in a distinct reaction environment.

[0016] The terms “comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of’ excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of’ excludes any component, step or procedure not specifically delineated or listed.

[0017] “Recycled polymer” refers to polymers, which were incorporated into products and subsequently re-melted to form a recycled polymer. The term “recycled polymer” refers to mechanically recycled polymers, where the polymer is melted and reincorporated into a new product. “Recycled polymer” does not include chemically recycled polymers, where the polymer is broken down into constituent monomers and incorporated into a new virgin polymer. Recycled polymers are defined in ISO 14021 7.8.1.1. The term “post-consumer recycled” (or “PCR”), as used herein, refers to a recycled polymeric material that includes materials previously used in a consumer or industry application (i.e., pre-consumer recycled polymer and post-industrial recycled polymer). PCR is typically collected from recycling programs and recycling plants. The PCR ethylene-based polymer may include one or more ethylene-based polymers, such as TDPE, TTDPE, HDPE, or polyethylene. The PCR may include one or more contaminants. The contaminants may be the result of the polymeric material’s use prior to being repurposed for reuse. For example, contaminants may include paper, ink, food residue, or other recycled materials in addition to the polymer, which may result from the recycling process. PCR is distinct from virgin polymeric material. A virgin polymeric material (such as a virgin polyethylene resin) does not include materials previously used in a consumer or industry application. Virgin polymeric material has not undergone, or otherwise has not been subject to, a heat process or a molding process, after the initial polymer manufacturing process. The physical, chemical, and flow properties of PCR resins differ when compared to virgin polymeric resin, which in turn can present challenges to incorporating PCR into formulations for commercial use. Post-consumer resin is defined in ISO 14021 7.8.1.1.

[0018] Bimodal Ethylene-Based Polymers

[0019] Embodiments of the present disclosure relate to bimodal ethylene-based polymers. The bimodal ethylene-based polymer may be the polymerized reaction product of ethylene and one or more C3-C14 olefinic comonomers.

[0020] Suitable C3-C14 olefinic comonomers may include, by way of example but not limitation, propylene, 1 -butene, 1 -pentene, 1 -hexene, 4-methyl-l -pentene, 1 -heptene, 1- decene and 1 -octene, as well as other monomer types such as styrene, alkyl-substituted styrenes, vinyl benzocyclobutane, dienes such as 1,4-hexadiene, 1,7-octadiene, 1,9-decadiene, and ethylidene norbornene and cycloalkenes (e.g., cyclopentene, cyclohexene and cyclooctene). The bimodal ethylene-based polymer may comprise from 1 to 49 wt. % of the C3-C14 olefinic comonomers, on the basis of the total polymer weight of the bimodal ethylenebased polymer. In embodiments, the bimodal ethylene-based polymer may comprise from 1 to 45 wt. %, from 1 to 35 wt. %, from 1 to 20 wt. %, from 1 to 5 wt. %, from 5 to 10 wt. %, from 10 to 15 wt. %, from 15 to 20 wt. %, from 20 to 25 wt. %, wt. %, from 25 to 30 wt. %, from 30 to 35 wt. %, from 35 to 40 wt. %, from 40 to 45 wt. %, from 45 to 49 wt. %, or any combination of two or more of these ranges of the C3-C14 olefinic monomers, on the basis of the total weight of the bimodal ethylene-based polymer. Methods of producing the bimodal ethylene-based polymers are disclosed in PCT Patent Appln. Nos. WO2019241475A1, WO2019241518A1, and WO2019241518A, which are incorporated herein by reference in their entireties.

[0021] The bimodal ethylene-based polymer may have a high density fraction (HDF) from 12.0% to 35.0%. Generally, having an HDF from 12.0 % to 35.0% is believed to result in increased dart performance. In embodiments, the bimodal ethylene-based polymer may have a HDF from 12.0% to 30.0%, from 12.0% to 14.5%, from 14.5% to 17.5%, from 17.5% to 20.0%, from 20.0% to 22.5%, from 22.5% to 25.0%, from 25.0% to 27.5%, from 27.5% to 30.0%, from 30.0% to 32.5%, from 32.5% to 35%, or any combination of two or more of these ranges. The HDF is defined as a ratio of the mass eluted at temperatures from 93 °C to 119 °C to the total mass eluted when measured using an improved comonomer content distribution (iCCD) curve of mass eluted versus temperature.

[0022] The HDF of the bimodal ethylene-based polymer may have a weight averaged molecular weight (Mw) of less than 120,000 g / mol. Generally, when the HDF has a lower Mw, it allows the FDF to have a higher molecular weight, which results in improved dart impact performance. In embodiments, the HDF may have a molecular weight of less than 110,000 g / mol, less than 100,000 g / mol, less than 98,000 g / mol, less than 95,000 g / mol, less than 90,000 g / mol, less than 85,000 g / mol, less than 80,000 g / mol, less than 75,000 g / mol, less than 70,000 g / mol, from 40,000 g / mol to 120,000 g / mol, from 40,000 g / mol to 50,000 g / mol, from 50,000 g / mol to 60,000 g / mol, from 60,000 g / mol to 70,000 / g / mol, from 70,000 g / mol to 80,000 g / mol, from 80,000 g / mol to 90,000 g / mol, from 90,000 g / mol to 100,000g / mol, from 100,000 to 110,000 g / mol, from 110,000 to 120,000 g / mol, or any combination of two or more of these ranges.

[0023] In embodiments, the HDF may have a single peak in the temperature range of from 90 °C to 119 °C. Generally, when the HDF has a higher peak temperature (such as in the range of from 90 °C to 119 °C), it allows the LDF to have a lower peak temperature, which results in improved dart impact performance. As used herein, a “single peak” refers to an iCCD wherein a particular fraction include only a single peak. That is, in some embodiments, the iCCD of the HDF and / or the LDF includes only an upward sloping region followed by a downward sloping region to form the single peak. In embodiments, the HDF may have a peak temperature of from 90 °C to 92 °C, from 92 °C to 94 °C, from 94 °C to 96 °C, from 96 °C to 98 °C, from 98 °C to 100 °C, from 100 °C to 105 °C, from 105 °C to 110 °C, from 110 °C to 115 °C, from 115 °C to 119 °C, or any combination of two or more of these ranges.

[0024] The bimodal ethylene-based polymer may have a low density fraction (LDF)of from 65.0% to 88.0%. In embodiments, the bimodal ethylene-based polymer may have an LDF from 65.0 % to 68.0 %, from 68.0% to 71%, from 71.0% to 74.0%, from 74.0% to 77.0%, from 77.0% to 80. 0%, from 80.0% to 83.0%, from 83.0% to 86.0%, from 86.0% to 88.0%, or any combination of two or more of these ranges. The LDF being defined as a ratio of the mass eluted at temperatures from 30 °C to transition point X to the total mass eluted when measured using an improved comonomer content distribution (iCCD) curve of mass eluted versus temperature. Transition point X is determined individually for each sample using the iCCD test as follows. Initially, predefined boundaries set the transition range from a minimum to a maximum value (75 °C to 96 °C, respectively). Then, the temperature is iterated, within the specified boundaries, incrementing by 0.1 °C. At each temperature point, the first derivative of a fitted iCCD function with respect to temperature is calculated. The transition temperature X is the point where the first derivative changes sign from negative to positive.

[0025] The LDF may have a weight averaged molecular weight (Mw) of greater than 100,000 g / mol. Generally, when the LDF has a higher Mw (e.g., greater than 100,000 g / mol), the polymer is believed to include a relatively greater concentration of tie chains, which is believed to result in improved dart performance. In embodiments, the LDF may have a Mwof greater than 105,000 g / mol, greater than 110,000 g / mol, greater than 115,000 g / mol, greater than 120,000 g / mol, greater than 125,000 g / mol, greater than 130,000 g / mol, from 100,000 g / mol to 150,000 g / mol, from 105,000 g / mol to 110,000 g / mol, from 110,000 g / mol to 120,000 g / mol, from 120,000 g / mol to 130,000 g / mol, from 130,000 g / mol to 140,000 g / mol, from 140,000 g / mol to 150,000 g / mol, or any combination of two or more of these ranges.

[0026] The LDF may have a single peak in the temperature range of from 69 °C to 85 °C. Generally, when the LDF peak is in the specified temperature range (e.g., 69 °C to 85 °C or 76 °C to 85 °C), a relatively great concentration of tie chains will be present, resulting in improved dart performance. In embodiments, the LDF may have a peak temperature of from 76 °C °C to 85 °C, from 690to 70 °C, from 70 °C to 72.5 °C, from 72.5 °C to 75 °C, from 75 °C to 76 °C, from 76 °C to 78 °C, from 78 °C to 80 °C, from 80 °C to 82.5 °C, from 82.5 °C to 85 °C, or any combination of two or more of these ranges.

[0027] In embodiments, the absolute value of the difference (A Mw) between the Mw of the HDF and the Mw of the LDF (MWHDF - MWLDF) may be greater than 25,000 g / mol. Generally, it is believed that a greater absolute value of A Mw of the bimodal ethylene-based polymer results in greater dart impact resistance of the resulting film. In embodiments, the absolute value of A Mw may be greater than 27,500 g / mol, greater than 30,000 g / mol, greater than 35,000 g / mol, greater than 40,000 g / mol, greater than 45,000 g / mol, greater than 50,000 g / mol, from 25,000 g / mol to 110,000 g / mol, from 25,000 g / mol to 30,000 g / mol, from 30,000 g / mol to 35,000 g / mol, from 35,000 g / mol to 40,000 g / mol, from 40,000 g / mol to 45,000 g / mol, from 45,000 g / mol to 50,000 g / mol, from 50,000 g / mol to 60,000 g / mol, from 60,000 g / mol to 70,000 g / mol, from 70,000 g / mol to 80,000 g / mol, from 80,000 g / mol to 90,000 g / mol, from 90,000 to 100,000 g / mol, from 100,000 to 110,000 g / mol, or any combination of two or more of these ranges. In embodiments, A Mw may be a negative number. Generally, it is believed that a greater absolute value of A Mw, when A Mw is negative, of the bimodal ethylene-based polymer results in greater dart impact resistance of the resulting film.

[0028] In embodiments, the difference (A T) between the peak temperature of the HDF and the peak temperature of the LDF may be at least 15 °C. Generally, it is believed that greater A T of the bimodal ethylene-based polymer results in greater dart impact resistance of theresulting film. In embodiments, the A T may be at least 16 °C, at least 17 °C, at least 18 °C, from 15 °C to 35 °C, from 15 °C to 17.5 °C, from 17.5 °C to 20 °C, from 20 °C to 22.5 °C, from 22.5 °C to 25 °C, from 25 °C to 27.5 °C, from 27.5 °C to 30 °C, from 30 °C to 32.5 °C, from 32.5 °C to 35 °C, or any combination of two or more of these ranges.

[0029] The bimodal ethylene-based polymer may have a soluble fraction (SF) (also referred to herein as a purge fraction) less than 2.0%. In embodiments, the bimodal ethylene-based polymer may have an SF less than 1.8%, less than 1.6%, less than 1.4%, less than 1.2%, less than 1.0%, less than 0.8%, less than 0.6%, or less than 0.4%. The SF is defined as a ratio of the mass eluted at temperatures less than 35 °C to the total mass eluted when measured according to iCCD.

[0030] The bimodal ethylene-based polymer may have a molecular weight Mn (conventional) of at least 19,000 g / mol. In embodiments, the bimodal ethylene-based polymer may have a Mn (conventional) of from 19,000 g / mol to 25,000 g / mol, from 25,000 g / mol to 30,000 g / mol, from 30,000 g / mol to 35,000 g / mol, from 35,000 g / mol to 40,000 g / mol, from 40,000 g / mol to 45,000 g / mol, from 45,000 g / mol to 50,000 g / mol, or any combination of two or more of these ranges.

[0031] The bimodal ethylene-based polymer may have a density of from 0.900 g / cc to 0.925 g / cc. In embodiments, the bimodal ethylene-based polymer may have a density of from 0.900 g / cc to 0.905 g / cc, from 0.905 g / cc to 0.910 g / cc, from 0.910 g / cc to 0.915 g / cc, from 0.915 g / cc to 0.920 g / cc, from 0.920 g / cc to 0.925 g / cc, or any combination of two or more of these ranges.

[0032] The bimodal ethylene-based polymer may have a melt index (h) from 0.5 g / 10 mins to 7.0 g / 10 mins. In embodiments, the bimodal ethylene-based polymer may have an I2 from 0.5 g / 10 mins to 6.0 g / 10 mins, from 0.5 g / 10 mins to 5.0 g / 10 mins, from 0.5 g / 10 mins to 4.0 g / 10 mins, from 0.5 g / 10 mins to 3.0 g / 10 mins, from 0.5 g / 10 mins to 2.0 g / 10 mins, from 0.5 g / 10 mins to 1.5 g / 10 mins, from 0.5 g / 10 mins to 1.0 g / 10 mins, from 0.5 g / 10 mins to 0.95 g / 10 mins, from 0.5 g / 10 mins to 0.7 g / 10 mins, from 0.7 g / 10 mins to 0.9 g / 10 mins, from 0.9 g / 10 mins to 0.98 g / 10 mins, from 0.98 g / 10 mins to 2 g / 10 g / 10 mins, or any combination of two or more of these ranges.

[0033] The bimodal ethylene-based polymer may have an I10 / I2 ratio from 5.5 to 7.0, such as from 5.5 to 6.7, from 5.8 to 6.6, from 5.5 to 5.6, from 5.6 to 5.8, from 5.8 to 6.2, from 6.2 to 6.6, from 6.6 to 6.7, from 6.7 to 6.8, from 6.8 to 7.0, or any combination of two or more of these ranges.

[0034] The bimodal ethylene-based polymer may have a viscosity ratio (Vo 1 / V100) of from 2 to 4.5. In embodiments, the bimodal ethylene-based polymer may have a viscosity ratio (Vo 1 / V100) of from 2 to 2.3, from 2.3 to 2.7, from 2.7 to 3.0, from 3.0 to 3.3, from 3.3 to 3.6, from 3.6 to 3.9, from 3.9 to 4.25, from 4.25 to 5, or any combination of two or more of these ranges.

[0035] Polymer Blends

[0036] Embodiments of the present disclosure relate to polymer blends. The polymer blends generally comprise the bimodal ethylene-based polymer described hereinabove and postconsumer recycled (PCR) ethylene-based polymer. The bimodal ethylene-based polymer may be a virgin polymer. Generally, the incorporation of PCR ethylene-based polymers into a blend results in reduced material properties (e.g., reduced dart), relative to a virgin polymer. Often, producers attempt to compensate for these reduced dart properties by utilizing a virgin polymer with extremely high dart. However, traditional, extremely high dart polymers often have low processability or tear performance and are thus unsuitable. Surprisingly, the bimodal ethylene-based polymers of the present disclosure do not experience the same reduction in material properties as conventional polymers, when blended with the PCR ethylene-based polymer.

[0037] The PCR ethylene-based polymer may be an ethylene-based polymer having a density of 0.910 to 0.930 g / cc, such as from 0.910 to 0.915, from 0.915 to 0.920, from 0.920 to 0.925, from 0.925 to 0.930, or any combination of two or more of these ranges. The PCR ethylenebased polymer may be an ethylene-based polymer having a melt index (I2) of 0.3 to 2 dg / min, such as from 0.3 to 0.5 dg / min, from 0.5 to 0.8 dg / min, from 0.8 to 1.1 dg / min, from 0.1 to 1.4 dg / min, from 1.4 to 1.7 dg / min, from 1.7 to 2.0 dg / min, or any combination of two or more of these ranges. The PCR ethylene-based polymer may comprise an EDPE, an HDPE, an EEDPE, or a blend thereof. In embodiments, the PCR ethylene-based polymer resin comprise at least 50 wt. %, at least 75 wt. %, at least 85 wt. %, at least 90 wt. %, at least 95wt. %, or even at least 99 wt. % of an LDPE, an HDPE, an LLDPE, or a blend thereof, on the basis of the total weight of the PCR ethylene-based polymer. Suitable PCR ethylene-based polymers include AVANGARD™ NATURA PCR-LDPCR- 100 (“AVANGARD™ 100”) and AVANGARD™ NATURA PCR-LDPCR-150 (“AVANGARD™ 150”) (PCR commercially available from Avangard Innovative LP, Houston, Texas).

[0038] The polymer blend may comprise from 10 to 50 wt.% PCR ethylene-based polymer, such as from 10 to 15 wt. %, from 15 to 20 wt. %, from 20 to 25 wt. %, from 25 to 30 wt. %, from 30 to 35 wt. %, from 35 to 40 wt. %, from 40 to 45 wt. %, from 45 to 50 wt. %, or any combination of two or more of these ranges.

[0039] Additives

[0040] It should be understood that the above-described bimodal ethylene-based polymers, the polymer blends, or films produced therefrom may further include one or more additives as known to those of skill in the art such as, for example, plasticizers, stabilizers including viscosity stabilizers, hydrolytic stabilizers, primary and secondary antioxidants, ultraviolet light absorbers, anti-static agents, dyes, pigments or other coloring agents, inorganic fillers, fire-retardants, lubricants, reinforcing agents such as glass fiber and flakes, synthetic (for example, aramid) fiber or pulp, foaming or blowing agents, processing aids, slip additives, anti-block agents such as silica or talc, release agents, tackifying resins, or combinations of two or more thereof. Inorganic fillers, such as calcium carbonate, and the like can also be incorporated into the film. In embodiments, the bimodal ethylene-based polymers, the polymer blends, or films produced therefrom may comprise from 0 to 40 wt. %, such as from 0 to 30 wt. %, from 0 to 20 wt. %, from 0 to 10 wt. %, from 1 to 40 wt. %, from 1 to 30 wt. %, from 1 to 20 wt. %, or from 1 to 10 wt. % of additives.

[0041] Film

[0042] Additional embodiments of the present disclosure are directed to films. The films may include the bimodal ethylene-based polymers and / or polymer blends described herein. In embodiments, the films may comprise at least 80 wt. %, at least 90 wt. %, at least 95 wt. %, or at least 99 wt. % of the bimodal ethylene-based polymers and / or polymer blends described herein. In embodiments, the film is substantially free of any other polymeric component.

[0043] The film of may be a monolayer or multilayer film, such as a film having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 layers. One or more of the layers of a multilayer film may comprise the bimodal ethylene-based polymers and / or polymer blends described herein. In embodiments, the layer or layers comprising the bimodal ethylene-based polymers and / or polymer blends may each comprise at least 80 wt. %, at least 90 wt. %, at least 95 wt. %, or at least 99 wt. % of the bimodal ethylene-based polymers and / or polymer blends described herein. The films of the present disclosure can 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 the multilayer film, the desired properties of the film, the desired end-use application of the film, the manufacturing process of the film, and others. In embodiments, the film may have a thickness of 0.5 to 5 mils, from 1 to 4 mils, from 1 to 3 mils, or from 1.5 to 2.5 mils, from 2.5 to 5 mils, from 5 to 10 mils, from 10 to 20 mils, from 20 to 40 mils, from 40 to 60 mils, or any combination of two or more of these ranges.

[0044] The film may have a haze of less than 25%, such as less than 20%, less than 15%, or less than 10%. The film may have an MD-Tear of greater than 800 gf, such as greater than 825 gf, greater than 850 gf, or greater than 870 gf. The film may have a dart impact of at least 500 g, such as at least 525 g, at least 550 g, at least 575 g, at least 600 g, at least 650 g, at least 700 g, at least 750 g, at least 800 g, at least 850 g, at least 900 g, or at least 1000 g. Film properties are measured at a thickness of 2 mils.

[0045] Various methodologies are contemplated for producing the films of this disclosure. In one or more embodiments, the process of manufacturing the film may include cast film extrusion or blown film extrusion.

[0046] Articles

[0047] Embodiments of the present disclosure also relate to articles, such as packages, formed from the films of the present disclosure. The films of the present disclosure are particularly useful in articles where good tear strength and dart strength are desired. Examples of such articles can include flexible packages, pouches, stand-up pouches, and pre-made packages or pouches. Various methods of producing embodiments of articles from the films disclosed herein would be familiar to one of ordinary skill in the art.TEST METHODS

[0048] Improved method for comonomer content analysis (iCCD)

[0049] Details of the ICCD method can be found in U.S. Patent Application Number 17 / 632598, which is incorporated by reference herein.

[0050] Density

[0051] Samples for density measurement are prepared according to ASTM D 1928. Polymer samples are pressed at 190 °C and 30,000 psi for three minutes, and then at 21 °C and 207 MPa for one minute. Measurements are made within one hour of sample pressing using ASTM D792, Method B.

[0052] Melt Index (I2) and (I10)

[0053] Melt index, or I2, (grams / 10 minutes or dg / min) is measured in accordance with ASTM D 1238, Condition 190 °C / 2.16 kg, Procedure B. Melt index, or I10, (grams / 10 minutes or dg / min) is measured in accordance with ASTM D 1238, Condition 190 °C / 10 kg, Procedure B.

[0054] Haze

[0055] Haze is measured using a Byk Haze-Gard I. After thickness measurement, the film sample is held against the lens at the integrating sphere end of the Haze-Gard I where it measures an Illuminant A value in accordance with ASTM DI 003. This test is performed first, since it is non-destructive.

[0056] Instrumented Dart Impact (IDI)

[0057] IDI is measured according ASTM D7192. This standard requires a probe assembly of 12.70 ± 0.13 mm diameter with hemispherical end of the same diameter. The probe used has a 4500 N range with 1.1 mV / N sensitivity and is designed for dynamic measurements. The dart probe assembly is mounted atop a EinMot linear motor, which is an electromagnetic direct drive motor in tubular form. It has a maximum velocity of 5.4 m / s and maximum force of 1650 N.

[0058] MD Tear

[0059] MD Tear was tested according to ASTM DI 922- 15, covering the average force required to propagate tearing through a specified length of plastic film after the tear has been started using an Elmendorf type tearing tester.

[0060] Gel Permeation Chromatography (GPC)

[0061] Details of the GPC method can be found in U.S. Patent Application Number 17 / 632598, which is incorporated by reference herein.EXAMPLES

[0062] The following examples illustrate features of the present disclosure but are not intended to limit the scope of the disclosure. The following experiments analyzed the performance of embodiments of the bimodal ethylene-based polymers described herein.

[0063] Production of Bimodal Ethylene-Based Polymers

[0064] All raw materials (monomer and comonomer) and the process solvent (a narrow boiling range high-purity paraffinic and cycloparaffinic solvent) are purified with molecular sieves before introduction into the reaction environment. High purity hydrogen is used to terminate the polymerization reaction. The reactor monomer feed stream is pressurized via a mechanical compressor to above reaction pressure. The solvent feed is pressurized via a pump to above reaction pressure. The comonomer feed is pressurized via a pump to above reaction pressure. The individual catalyst components are manually batch diluted to specified component concentrations with purified solvent and pressured to above reaction pressure. All reaction feed flows are measured with mass flow meters and independently controlled with metering pumps.

[0065] The reactor configuration used consists of a liquid full, adiabatic, and continuously stirred tank reactor (CSTR) as the first reactor, followed by a plug flow reactor as the second reactor. Independent control of all solvent, monomer, comonomer, hydrogen, and catalyst component feeds is possible. The total feed stream (solvent, monomer, comonomer, and hydrogen) is fed to the first reactor. The catalyst components are injected into the firstpolymerization reactor separate from the other feeds, additional catalyst and co-catalyst components are optionally injected into the plug flow reactor. An agitator in the reactor is responsible for continuously mixing of the reactants in the CSTR. An oil bath provides for some fine tuning of the reactor temperature control.

[0066] The final reactor effluent (second reactor effluent for dual series, the combined effluent for dual parallel, or the single reactor effluent) enters a zone where it is deactivated with the addition of and reaction with a suitable reagent (typically water). At this same reactor exit location other additives may also be added for polymer stabilization (Octadecyl 3,5-Di- Tert-Butyl-4-Hydroxyhydrocinnamate, Tetrakis (Methylene(3,5-Di-Tert-Butyl-4- Hydroxyhydrocinnamate)) Methane, and Tris(2,4-Di-Tert-Butyl-Phenyl) Phosphite).

[0067] Following catalyst deactivation and any additive addition, the reactor effluent enters a devolatilization system where the polymer is removed from the non-polymer stream. The non-polymer stream is removed from the system. The isolated polymer melt is pelletized and collected.

[0068] Reaction conditions are as disclosed in Table 1 : Reaction Conditions The reactor used was a single reactor with a plug flow reactor outlet (referred to in the table as RXR 2). For all reactions disclosed in Error! Reference source not found., the monomer was ethylene and the comonomer was octene.Table 1: Reaction ConditionsTable 1: ContinuedTable 1: Continued

[0069] In Table 1, the catalysts are as follows:

[0070] Comparative Polymers

[0071] DOWLEX™ GM 8090, a linear low density polyethylene (LLDPE) having a density of 0.916 g / cc and melt index (12) of 1.0 g / 10 min, and commercially available from The Dow Chemical Company (Midland, MI), was utilized as comparative example C2. DOWLEX™ GM 8090 is an ethylene-based polymer as that term is defined herein.

[0072] EXCEED™ 1018, a metallocene catalyst ethylene / hexane copolymer having an L of 1 g / 10 minutes and density of 0.918 g / cm3, and commercially available from ExxonMobil Chemical was utilized as comparative example C3.

[0073] LLDPE- 1 was utilized as comparative example C4. LLDPE- 1 is a linear low density polyethylene (LLDPE) having a density of 0.917 g / cc and melt index (12) of 1.0 g / 10 min.

[0074] Characterization of Bimodal Ethylene-Based Polymers

[0075] The bimodal ethylene-based polymers described herein, and the comparative examples, were subjected to GPC testing, the results of which are given in Table 2. Molecular weights are given in grams / mol.Table 2

[0076] The samples were subjected to iCCD testing, the results of which are given in Table 3. Temperatures are given in °C and molecular weights are given in grams / mol.Table 3

[0077] The samples were subjected to rheology testing. Results are given in Table 4.Table 4

[0078] Bimodal Ethylene-Based Polymer Films

[0079] Line 1

[0080] Two mil blown films were made using a monolayer Dr. Collin blown film line. The line utilizes a 30:1 L / D single screw extruder, equipped with grooved feed zones, and a 30 mm screw diameter. The annular die was 60 mm in diameter and used a dual lip air ring cooling system. The die lip gap was 2 mm and the blow up ratio (BUR) was 2.0. The lay flat width was around 48 cm. The frost line height was 5-6 inches. The total output rate was 5-8 kg / hour. The melt temperature was 200-220 °C, and the die temperature was set at 225 °C.

[0081] Line 2

[0082] Two mil blown films were made by using a gravimetric feeders to dose resin formulations into a Labtech LTE20-32 twin screw extruder at rate of 15 Ibs / hr. From the extruder, the resin formulation was conveyed into the 2” die diameter die with gap of 1.0 mm. The Labtech feed throat was set to 193 °C and the remaining barrel, conveying portion, and die temperature were set and maintained to 215 °C. Pressurized ambient air was used to inflate the film bubble to a 2.5 blow-up ratio. A dual lip air ring driven by a variable speed blower was used for all experiments. The frost line height (FLH) was maintained between 8.8 and 10.8 inches. Film thickness was targeted at 2 mils and was controlled within ± 15% by adjusting the nip roller speed. The films are wound up into a roll.

[0083] Line A

[0084] Two mil blown films were made on a single 3.5 inch diameter 30:1 L / D Sterling ran at a rate of 250 Ibs / hr. Film was fabricated using an 8 inch die diameter using 1BC (internalbubble cooling). External cooling was provided by a Hosokowa Alpine air ring which operated in sequence with a Kundig gauge scanner to control gauge variation. Film then passed on to a single turret Gloucester high speed (1000 ft / min max) winder where it was collected on a 3” core for sampling. The blow up ratio (BUR) was 2.0 with film thickness targeted at 2 mils.

[0085] Properties of the resulting films are given in Table 5.Table 5

[0086] As can be seen in Table 5, the bimodal ethylene-based polymer films of the present disclosure have improved dart impact resistance, relative to the comparative film. Additionally, higher AT and AMw is correlated with higher dart impact resistance.

[0087] Films Formed From Polymer Blends

[0088] AVANGARD™ NATURA PCR-FDPCR-100, a PCR commercially available from Avangard Innovative TP, Houston, Texas (hereinafter “PCR”), is a post-consumer recycled ethylene-based polymer with a melt index (H) of 2 dg / min and a density of 0.914 g / cc.

[0089] DOWFEX™ 2045 G, a monomodal EEDPE produced in a single reactor, with a melt index (I2) of 1 dg / min, and a density of 0.92 g / cc, commercially available from Dow Inc. Midland MI, was used as comparative resin CR-1. iCCD properties of CR-1 are given in Table 3.

[0090] INNATE™ ST50, an LLDPE with a melt index (I2) of 0.83 dg / min, and a density of 0.918 g / cc, commercially available from Dow Inc. Midland MI, was used as comparative resin CR-2. iCCD properties of CR-2 are given in Table 3.

[0091] Example El l was used as the bimodal ethylene-based polymer.

[0092] 2 mil films containing blends of PCR and bimodal ethylene-based polymers in varying ratios were prepared on Line 2 as described above. Additionally, films comprising other LLDPEs and PCR, as well as virgin resin controls were prepared. The Dart and Tear performance of the films was then tested.

[0093] Table 6 discloses the dart and tear performance of virgin bimodal ethylene-based polymers and mixtures of 75 wt. % virgin ethylene-based polymer with 25 wt. % PCR.Table 6

[0094] As can be seen from Table 6, the bimodal ethylene-based polymer El l shows significantly better dart impact after the incorporation of PCR than the comparative examples. Further, El 1 show much less degradation after incorporation than comparative resin CR-2.

[0095] Table 7 shows the ASTM normalized dart drop impact and Elmendorf MD Tear of the prepared films.Table 7

[0096] As can be seen from Table 7, the incorporation of PCR into El l results in less significant drop in dart impact performance than the incorporation of PCR into the comparative resins.

[0097] Table 8 shows the effect on Haze of incorporating PCR into the polymers of Example E5 and comparative resins CR-1 and CR-2.Table 8

Claims

CLAIMS1. A bimodal ethylene-based polymer, the bimodal ethylene-based polymer being the polymerized reaction product of ethylene and one or more C3-C14 olefinic comonomers, wherein the bimodal ethylene-based polymer comprises: a high density fraction (HDF) from 12.0% to 35.0%, the HDF being defined as a ratio of the mass eluted at temperatures from 93 °C to 119 °C to the total mass eluted when measured using an improved comonomer content distribution (iCCD) curve of mass eluted versus temperature; an I10 / I2 ratio from 5.5 to 7.0, wherein I2 is the melt index when measured according to ASTM D 1238 at a load of 2.16 kg and temperature of 190° C. and I10 is the melt index when measured according to ASTM D 1238 at a load of 10 kg and temperature of 190° C; and the high density fraction has a molecular weight (Mw) of less than 120,000 g / mol.

2. The bimodal ethylene-based polymer of claim 1, wherein the bimodal ethylene-based polymer has a delta temperature between the HDF and the LDF of at least 15 °C.

3. The bimodal ethylene-based polymer of claim 1 or 2, wherein a soluble fraction (SF) less than 2.0%, the SF being defined as a ratio of the mass eluted at temperatures less than 35 °C to the total mass eluted when measured according to iCCD.

4. The bimodal ethylene-based polymer of any one of claims 1 to 3, wherein the bimodal ethylene-based polymer has an absolute value of delta Mw between the HDF and the LDF of greater than 25,000 g / mol.

5. The bimodal ethylene-based polymer of any one of claims 1 to 4, wherein the bimodal ethylene-based polymer has a molecular weight Mn (conventional) of at least 19,000 g / mol.

6. The bimodal ethylene-based polymer of any one of claims 1 to 5, wherein the bimodal ethylene-based polymer has a density from 0.900 g / cc to 0.925 g / cc.

7. The bimodal ethylene-based polymer of any one of claims 1 to 6, wherein the bimodal ethylene-based polymer has a melt index (I2) from 0.5 g / 10 mins to 7.0 g / 10 mins.

8. The bimodal ethylene-based polymer of any one of claims 1 to 7, wherein the bimodal ethylene-based polymer has an I10 / I2 ratio from 5.8 to 6.6.

9. The bimodal ethylene-based polymer of any one of claims 1 to 8, wherein the bimodal ethylene-based polymer has a Vo 1 / V100 of from 2.5 to 4.5.

10. A polymer blend comprising: the bimodal ethylene-based polymer of any one of claims 1 to 9, wherein the bimodal ethylene-based polymer is a virgin polymer; and post-consumer recycled (PCR) ethylene-based polymer having a density of 0.910 to 0.930 g / cc and a melt index (I2) of 0.3 to 2 dg / min as measured according to ASTM D1238 (190C, 2.16 Kg).

11. The polymer blend of claim 10, wherein the polymer blend comprises from 10 to 50 wt.% PCR ethylene-based polymer.

12. A film comprising the bimodal ethylene-based polymer any one of claims 1 to 11, wherein the film is a monolayer film or a multilayer film.

13. The film of claim 12, wherein the film has a haze of less than 45%.

14. The film of claim 12 or 13, wherein the film has an Elmendorf MD-Tear of greater than 500 gf.

15. The film of any one of claims 12 to 14, wherein the film has an ASTM dart impact of at least 1000 g.

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