CN114787250A

CN114787250A - Biaxially oriented polyethylene film and method for producing the same

Info

Publication number: CN114787250A
Application number: CN202080085049.5A
Authority: CN
Inventors: N·罗科; M·W·赫尔特卡姆; K·A·史蒂文斯; T·L·布兰顿; S·J·波恩哈特
Original assignee: ExxonMobil Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 2019-12-09
Filing date: 2020-12-09
Publication date: 2022-07-22
Also published as: EP4073154A1; WO2021119158A1

Abstract

The present invention relates to a biaxially oriented polyethylene film comprising polyethylene having: (A) melt index I₂1.0g/10min or more, and (B) has a density of 0.925g/cm³To 0.945g/cm³，(C)g'_visLess than 0.8, (D) Mz of 1,000,000G/mol or more, (E) Mw/Mn of 5 or more, (F) Mw of 100,000G/mol or more, (G) G'_LCBAnd g'_ZaveA ratio of (a) greater than 1.0, and (H) a strain hardening ratio of 4 or greater, wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater, and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

Description

Biaxially oriented polyethylene film and method for producing the same

Cross Reference to Related Applications

The present invention claims the benefit of U.S. provisional application No. 62/945765 entitled "Biaxially ordered Polyethylene Films and Process for Production Thereof," filed on 9/12/2020, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to biaxially oriented polyethylene films.

Background

Films having high strength characteristics, including tensile strength and impact toughness, are desirable for packaging applications, including food packaging and stretch wrap, shrink wrap, and grocery sacks. Increasingly thinner films exhibiting high strength requirements provide the consumer with a better cost-performance relationship. The biaxial orientation of the polymer film can be used to improve strength properties while reducing the thickness of the film.

The packaging applications for biaxially oriented films are predominantly polypropylene. For example, over 60% of the biaxially oriented film market is represented by polypropylene and is obtained using a sequential tenter process. The strength and success of biaxially oriented polypropylene films is due to excellent processability (broad stretching temperature profile, slow crystallization), good overall properties, attractive cost (high production speed) and good yield (low density).

Polyethylene films have recently attracted interest in the art because polyethylene is more easily recycled. However, polyethylene tends to have a higher crystallinity than polypropylene, making it more difficult to reduce thickness and maintain a suitable balance of stiffness and toughness properties.

US9,068,033 discloses inter alia having g 'of less than 0.8'_vis0.25 to 1.5g/10min of an ethylene hexene copolymer having melt index I2, which is converted into a film.

U.S. patent nos.: US 5,955,625, US 6,168,826, US 6,225,426, US9,266,977, EP 2935367, US patent application publication nos. US 2008/0233375, US 2016/0031191, US 2015/0258756, US 2009/0286024, US 2018/0237558, US 2018/0237559, US 2018/0237554, US 2018/0319907, US 2018/0023788, WIPO patent application publication nos. WO 2017/127808, WO 2015/154253, WO 2015/138096, WO 1997/022470, japanese patent application publication No. 2016/147430; kim, W.N. et al (1994) "Morphology and Mechanical Properties of Biaxially ordered Films of Polypropylene and HDPE Blends," appl.Polym.Sci., Vol.54 (11), p.1741-1750; ratta, V. et al (2001) "Structure-Performance-Processing investments of the tester-Frame Process for Making Biaxially organized HDPE film.I. base Sheet and Draw Along the MD" Polymer, Vol. 42(21), p. 9059 and 9071; ajji, A. et al (2004) "Biaxial structuring and Structure of variant LLDPE Resins" Polymer.Eng.Sci., Vol.44 (2), p.252-260; ajji, A. et al (2006) "Biaxial organization in LLDPE Films: Complex of atomic Spectroscopy, X-ray Pole regulations, and Birefringence technologies," Polymer.Eng.Sci., Vol.46 (9), p.1182-1189; uehara, H et al (2004) "Stretchability and Properties of LLDPE Blends for Biaxially Oriented Film," Intern. Polymer Processing, Vol.19 (2), p.163; bobovitch, A.L. et al (2006) "Mechanical Properties Stress-Relaxation, and organization of Double rubber binary organized Polyethylene Films," J.Appl.Poly.Sci., Vol.100 (5), p.3545-3553; sun, T, et al (2001) Macromolecules, Vol.34 (19), pp.6812-6820; stadelhofer, J.et al (1975) "Darstellung und Eigenschten von Alkylmethyl cycles-Pentadiendervaten des olefins, Galliums und Indums," Jrn. organic chemical, Vol.84, pp.C 1-C4 and Chen, Q.et al (2019) "Structure Evolution of Polyethylene in Sequential Biaxial conversion orientation," Ind.Eng. chem. Res., Vol.58, pp.12419-12430.

Summary of The Invention

The present disclosure relates to biaxially oriented polyethylene films comprising polyethylene, such as Linear Low Density Polyethylene (LLDPE), having properties that improve processability while maintaining stiffness and high impact resistance.

The present invention relates to a biaxially oriented polyethylene film comprising a polyethylene having: (A) melt index I₂1.0g/10min or more, and (B) has a density of 0.92g/cm³To 0.94g/cm³，(C)g'_LCBLess than 0.8, (D) Mz of 1,000,000G/mol or more, (E) Mw/Mn of 5 or more, (F) Mw of 100,000G/mol or more, (G) G'_LCBAnd g'_ZaveA ratio of (a) greater than 1.0, and (H) a strain hardening ratio of 4 or greater, wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater, and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

The present disclosure also relates to compositions comprising: a biaxially oriented film comprising polyethylene having: (A) melt index I₂1.0g/10min or more, and (B) has a density of 0.925g/cm³To 0.945g/cm³，(C)g'_LCBLess than 0.8, (D) Mz of 1,000,000G/mol or more, (E) Mw/Mn of 5 or more, (F) Mw of 100,000G/mol or more, (G) G'_LCBAnd g'_ZaveA ratio of (a) greater than 1.0, and (H) a strain hardening ratio of 4 or greater, wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater, and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

The present disclosure also relates to a method comprising: producing a polymer melt comprising the polymer described above; extruding a film from a polymer melt; and stretching the film in the machine direction to produce a Machine Direction Oriented (MDO) polyethylene film; and stretching the MDO polyethylene film in the transverse direction to produce a biaxially oriented polyethylene film.

Detailed description of the invention

The present disclosure relates to biaxially oriented polyethylene films comprising LLDPE with well-defined properties that improve processability while maintaining mechanical properties such as stiffness, tensile strength, impact resistance and puncture resistance. More specifically, the polyethylene of the present disclosure has: (A) melt index I₂1.0g/10min or more, and (B) has a density of 0.925g/cm³To 0.945g/cm³，(C)g'_LCBLess than 0.8, (D) Mz is 1,000,000g/mol orMore, (E) Mw/Mn is 5 or more, (F) Mw is 100,000G/mol or more, (G) G'_LCBAnd g'_ZaveA ratio of (a) greater than 1.0, and (H) a strain hardening ratio of 4 or greater, wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater, and a ratio of 1% secant MD/1% secant TD of 0.65 or greater. The polyethylene can be further characterized by having: (A) melt index I₂1.5g/10min to 5g/10min, and (B) the density is 0.925g/cm³To 0.945g/cm³，(C)g'_LCBFrom less than 0.8 to 0.5, (D) Mz of 1,200,000G/mol or more, (E) Mw/Mn of 5 to 10, (F) Mw of 100,000 to 200,000G/mol, (G) G'_LCBAnd g'_ZaveA ratio of 1.5 to 10, and (H) a strain hardening ratio of 4.5 or more. Such LLDPE is easier to process and stretch. As a result, extruded polyethylene films can be stretched to a greater extent over a wider temperature window and achieve physical properties such as toughness of thicker films produced using other LLDPEs.

Definition and testing method

Unless otherwise indicated, room temperature was 25 ℃.

"olefins (olephins)" or "alkenes (alkenes)" are linear, branched or cyclic compounds of carbon and hydrogen having at least one double bond.

A "polymer" has two or more identical or different monomer (mer) units. A "homopolymer" is a polymer having the same monomer units. The term "polymer" as used herein includes, but is not limited to, homopolymers, copolymers, terpolymers, etc. The term "polymer" as used herein also includes impact, block, graft, random and alternating copolymers. Unless otherwise specifically indicated, the term "polymer" shall also include all possible geometrical configurations. Such configurations may include isotactic, syndiotactic and random symmetries.

As used herein, unless otherwise specified, the term "copolymer(s)" refers to a polymer formed by the polymerization of at least two different monomers (i.e., monomer units). For example, the term "copolymer" includes the copolymerization product of propylene and an alpha-olefin such as ethylene, 1-hexene. A "terpolymer" is a polymer having three monomer units that differ from each other. Thus, the term "copolymer" also includes terpolymer and tetrapolymer products such as a mixture of ethylene, propylene, 1-hexene, and 1-octene.

"different" as used to refer to monomeric units means that the monomeric units differ from each other by at least one atom or are isomerically different. An "ethylene polymer" or "ethylene copolymer" is a polymer or copolymer comprising at least 50 mole% ethylene derived units, a "propylene polymer" or "propylene copolymer" is a polymer or copolymer comprising at least 50 mole% propylene derived units, and the like. For the purposes of the present invention, polyethylene is an ethylene polymer.

As used herein, when a polymer is referred to as "comprising, consisting of, or consisting essentially of monomers," the monomers are present in the polymer as polymerized/derivatives of the monomers. For example, when a copolymer is said to have an "ethylene" content of 35 to 55 weight percent, it is understood that the monomer units in the copolymer are derived from ethylene in the polymerization reaction, and the derived units are present at 35 to 55 weight percent based on the weight of the copolymer.

"Low density polyethylene" LDPE has a density of greater than 0.90g/cm³To less than 0.94g/cm³The ethylene polymer of (a); such polyethylenes include copolymers made using heterogeneous catalytic processes (often identified as linear low density polyethylene LLDPE) and homopolymers or copolymers made using high pressure/free radical processes (often identified as LDPE). "Linear Low Density polyethylene" LLDPE is a polymer having a density of greater than 0.90g/cm³To less than 0.94g/cm³Preferably 0.910 to 0.935g/cm³And usually of g'_LCBAn ethylene polymer of 0.95 or greater. "high density polyethylene" ("HDPE") is a polyethylene having a density of about 0.94g/cm³Or larger ethylene polymers.

In g/cm³Density reported as a unit was determined according to ASTM 1505-10 (according to ASTM D4703-10a, procedure C, sheet preparation to mold a sheet, comprising conditioning the sheet at 23 ℃ CFor at least 40 hours to approach equilibrium crystallinity), where density measurements are made in a density gradient column.

As used herein, Mn is the number average molecular weight, Mw is the weight average molecular weight, and Mz is the z average molecular weight. Polydispersity index (PDI) is defined as Mw divided by Mn. Unless otherwise indicated, all molecular weights (e.g., Mw, Mn, Mz) are reported in g/mol.

Gel Permeation Chromatography (GPC) is a liquid chromatography technique used to measure molecular weight and polydispersity, particularly of polymers.

Unless otherwise indicated, moment (moment) and distribution of molecular weight (e.g., Mw, Mn, Mz, Mw/Mn) and comonomer content (e.g., C.sub.C.) were determined by high temperature gel permeation chromatography (Polymer Char GPC-IR) equipped with an infrared detector IR5, an 18-angle light scattering detector based on a multichannel bandpass filter, and a viscometer₂、C₃、C₆). Three Agilent PLGel 10-. mu.m mix-B LS columns were used to provide polymer separations. Aldrich reagent grade 1,2, 4-Trichlorobenzene (TCB) with 300ppm antioxidant Butylated Hydroxytoluene (BHT) was used as the mobile phase. The TCB mixture was filtered through a 0.1- μm teflon filter and degassed with an in-line degasser before entering the GPC instrument. The nominal flow rate was 1.0mL/min and the nominal injection volume was 200 μ L. The entire system including transfer lines, columns and detectors was housed in an oven maintained at 145 ℃. A polymer sample was weighed and sealed in a standard bottle with 80- μ L of flow marker (heptane) added to it. After loading the vial in the autosampler, the polymer was dissolved in the instrument with 8mL of added TCB solvent. The polymer was dissolved by shaking continuously at 160 ℃ for about 1 hour for polyethylene samples or about 2 hours for polypropylene samples. The TCB density used for concentration calculations was 1.463g/mL at room temperature and 1.284g/mL at 145 ℃. The sample solution concentration is 0.2-2.0mg/mL, with lower concentrations being used for higher molecular weight samples. The IR5 broadband signal intensity (I) from the subtracted baseline was used to calculate the concentration (c) at each point in the chromatogram using the following equation: where β is a mass constant. The integrated area and injection mass in the elution volume from the concentration chromatogramThe mass recovery was calculated as the ratio of (which is equal to the predetermined concentration times the volume of the injection circuit). The conventional molecular weight (IR molecular weight) was determined by combining the universal calibration relationship with a column calibration, which was performed with a series of monodisperse Polystyrene (PS) standards ranging from 700 to 10,000,000 gm/mole. The molecular weight at each elution volume was calculated using (1):

where the variables with subscript "PS" represent polystyrene and those without subscript represent test samples. In this process, α_PS0.67 and K_PS0.000175 and alpha and K for other materials as disclosed and calculated in the literature (Sun, t, et al (2001) Macromolecules, volume 34, page 6812), except for the purposes of the present invention and appended claims for linear propylene polymers alpha-0.705 and K-0.0002288, for linear butene polymers alpha-0.695 and K-0.000181, for ethylene-butene copolymers alpha-0.695 and K0.000579 (1-0.0087 w2b +0.000018 (w2b) ^2) where w2b is the bulk weight percentage of the butene comonomer, for ethylene-hexene copolymers alpha-0.695 and K0.000579 (1-0.5 w2b) where w2b is the bulk weight percentage of the hexene comonomer, and for ethylene-octene copolymers alpha-0.695 and K is 0072 (0073) where w2 is the bulk weight percentage of the hexene comonomer, 0073 and K is the bulk percentage of the 0072 comonomer 0073 (0073) where w2 is the bulk percentage of the comonomer 0073, and α is 0.695 and K is 0.000579 for all other linear ethylene polymers. Unless otherwise indicated, concentrations are in g/cm³Expressed in units, molecular weight is expressed in units of g/mole, and intrinsic viscosity (hence K in the Mark-Houwink equation) is expressed in units of dL/g.

By corresponding to CH₂And CH₃The comonomer composition was determined by the ratio of IR5 detector intensities for the channel (which was calibrated using a series of polyethylene and propylene homo/copolymer standards with NMR or FTIR predetermined nominal values). In particular, this provides methyl groups per 1,000 total Carbons (CH) as a function of molecular weight₃/1000 TC). This can then be applied to CH by applying chain-end correction₃The function of the/1000 TC,assuming each chain is linear and capped at each end with a methyl group, the Short Chain Branching (SCB) content per 1,000TC (SCB/1000TC) as a function of molecular weight was calculated. The wt% comonomer can then be obtained from the following expression, where for C₃、C₄、C₆、C₈And the comonomers f are respectively 0.3, 0.4, 0.6, 0.8, and the like:

w2 f SCB/1000TC equation 2

By considering CH between the integration limits of the concentration chromatogram₃And CH₂The entire signal of the channel acquires the bulk composition of the polymer from the GPC-IR and GPC-4D analyses. First, the following ratios were obtained.

Then applying CH₃And CH₂Calibration with equal signal ratio (as previously obtained CH as a function of molecular weight)₃Mentioned in/1000 TC) to obtain the bulk CH₃And/1000 TC. Bulk methyl chain ends/1,000 TC (bulk CH) were obtained by weighted average chain end correction over the molecular weight range₃End/1000 TC).

Then

w2b ═ f bulk CH₃/1000TC equation 4

The main body SCB/1000TC is the main body CH₃1000 TC-bulk CH₃End/1000 TC equation 5 converts the body SCB/1000TC to a body w2 in the same manner as described above.

The LS detector is an 18-angle Wyatt Technology High Temperature DAWN HELEOSII. The LS molecular weight (M) at each point in the chromatogram was determined by analyzing the output of the LS using a Zimm model for static Light Scattering (Light Scattering from Polymer Solutions, Huglin, m.b. editor, Academic Press, 1972):

here, Δ R (θ) is the excess Rayleigh scattering measured at the scattering angle θIntensity, c is the polymer concentration determined from IR5 analysis, A₂Is the second virial coefficient, P (theta) is the form factor of the monodisperse random coil, and K_oIs the optical constant of the system:

wherein N is_AIs the aflagaro constant, and (dn/dc) is the refractive index increment of the system, TCB n 1.500 at 145 ℃ and λ 665 nm. For the analysis of ethylene homopolymer, ethylene-hexene copolymer and ethylene-octene copolymer, dn/dc is 0.1048ml/mg and A₂0.0015; for the analysis of ethylene-butene copolymers, dn/dc 0.1048 (1-0.00126 w2) ml/mg and a₂0.0015 where w2 is the weight percent of butene comonomer, dn/dc 0.1048ml/mg for all other ethylene polymers and a₂＝0.0015。

Specific viscosities were measured using a high temperature viscometer such as those made by Technologies, inc. or Viscotek Corporation (which has four capillaries arranged in a wheatstone bridge configuration, and two pressure sensors). One sensor measures the total pressure drop across the detector and the other sensor, placed between the two sides of the bridge, measures the pressure difference. Calculating the specific viscosity eta of the solution flowing through the viscometer from their outputs_s. From equation [ η ]]＝η_sC calculating the intrinsic viscosity [ eta ] at each point in the chromatogram]Where c is concentration and is determined from the IR5 broadband channel output. The viscosity MW at each point was calculated as

Wherein alpha is_psIs 0.67 and K_PSIs 0.000175. Average intrinsic viscosity of the sample<[η]>By the following calculation:

where the sum is taken from all chromatographic sections i between the integration limits.

Long chain branching index (g'_LCBAlso called g'_vis) Is defined as

Wherein<M_IR>Are viscosity average molecular weights corrected using polystyrene standards, K and α are used for reference to linear polymers as disclosed and calculated in the literature (Sun, t, et al (2001) Macromolecules, volume 34, page 6812), except for the purposes of the present invention and appended claims, α ═ 0.705 and K ═ 0.0002288 for linear propylene polymers, α ═ 0.695 and K ═ 0.000181 for linear butene polymers, α ═ 0.695 and K ═ 0.000181 for ethylene-butene copolymers, α is 0.695 and K is 0.000579 (1-0.0087 w2 9238776 +0.000018 ^ w2b) for ethylene-butene copolymers (where w2b is the bulk weight percentage of butene comonomer), α is 0.695 and K is 0.000579 (1-0.0075 ═ w2) for ethylene-hexene copolymers (where w2 is the bulk weight percentage of butene comonomer), K is 0.4623 and K is the bulk weight percentage of ethylene-octene comonomer (1-0.0075 ═ w2) for ethylene-hexene copolymers (where K23 is the bulk weight percentage of comonomer and K is the bulk weight percentage of octene comonomer (3) for ethylene-octene copolymers, K3) and K is 0.462 weight percentage of the bulk comonomer (where K1 and K is the bulk percentage of the bulk comonomer of α -octene copolymer is 0.462 and K3) for ethylene-octene copolymer (3) and where K is 0.462 and where K is the bulk percentage of the weight percentage of the bulk comonomer (3) of the weight percentage of the comonomer (1 and the comonomer of the comonomer ) And α ═ 0.695 and K ═ 0.0005 for all other linear ethylene polymers.

G ' is determined by selecting a g ' value at Mz value on a GPC-4D trace produced by the GPC method described above '_Mz. The Mz values are obtained from the LS detector. For example, if Mz-LS is 300,000g/mol, the value at 300,000g/mol on the g' trace on the GPC-4D plot is used. G ' is determined by selecting a g ' value at the Mw value on the GPC-4D trace '_Mw. The Mw values were obtained from an LS detector. For example, if Mw-LS is 100,000g/mol, the value at 100,000g/mol on the g' trace on the GPC-4D plot is used. G ' is determined by selecting a g ' value at the Mn value on the GPC-4D trace '_Mn. The Mz values are obtained from the LS detector. For example, if Mn-LS is 50,000g/mol, the value at 50,000g/mol on the g' trace on the GPC-4D plot is used.

The comonomer content at Mw, Mn and Mz was determined by GPC-4D using molecular weight values obtained by an LS detector.

Small Amplitude Oscillatory Shear (SAOS) measurements were performed on an Anton Paar MCR702 rheometer. The samples were compression molded at 177 ℃ for 15 minutes (including cooling under pressure). Then, a 25mm test disc specimen was die cut from the resulting plate. The test was performed using a 25mm parallel plate geometry. Amplitude scanning was performed on all samples to determine the linear deformation region. For amplitude scanning, the strain is set to 0.1% -100% with a frequency of 6rad/sec and a temperature of 190 ℃. Once linearity is established, a frequency sweep is performed to determine the complex viscosity curve from 0.01rad/s to 500rad/s at 5% strain at T ═ 190 ℃.

To quantify the shear rheological behavior, we define the shear thinning extent (DST) parameter. DST is measured by the following expression:

wherein eta_0.01And η₅₀Is a complex viscosity measured at 190 ℃ at a frequency of 0.01rad/s and 50rad/s, respectively. The DST parameters help to better distinguish and emphasize the branching characteristics of the samples.

The extensional evolution of the instantaneous extensional viscosity was studied by means of an MCR501 rheometer with controlled working speed, available from Anton Paar. The Linear Viscoelastic Envelope (LVE) was obtained from a start-up steady state shear experiment. Strain hardening is defined as the rapid and sudden flattening of the extensional viscosity from a linear viscoelastic behavior (level off). This non-linear behavior is therefore quantified by the Strain Hardening Ratio (SHR), which is defined as 1s^-1Maximum instantaneous elongational viscosity of

Relative 0.1s^-1Ratio of the respective values of (a):

0.1s^-1is superior to LVE because only transient stretching is selected for use in the process rather than initiating steady state shear data. When the SHR is greater than 1, the material exhibits strain hardening.

Unless otherwise indicated, Differential Scanning Calorimetry (DSC) measurements were performed using TA Instruments' Discovery 2500. The melting point or melting temperature (Tm), crystallization temperature (Tc) and heat of fusion or heat flow (. DELTA.H) were determined using the following DSC procedure_fOr H_f). Samples weighing approximately 2mg to 5mg were sealed in an aluminum gas-tight pan. The heat flow was normalized by the sample mass. The DSC run was ramped from 0 ℃ to 200 ℃ at a rate of 10 ℃/min. After equilibration for 45 seconds, the sample was cooled down to 0 ℃ at 10 ℃/min. The first and second thermal cycles were recorded. Unless otherwise specified, DSC measurements are based on the 2 nd crystallization and melting ramp. Melting temperature (T) was calculated by integrating melting and crystallization peaks (area under the curve)_m) And crystallization temperature (T)_c). The endothermic melting transition was analyzed for transition onset and peak temperature, and if at least 7 ℃ between the transition onset and peak temperature, the endothermic melting transition was considered to exhibit a broad melting peak. For samples showing multiple peaks, the melting temperature is defined as the peak melting temperature from the DSC melting trace (i.e., related to the maximum endothermic thermal response in this temperature range).

As used herein, a "peak" occurs where the sign of the first derivative of the corresponding curve changes from a positive value to a negative value. As used herein, a "valley" occurs where the first derivative of the corresponding curve changes from a negative value to a positive value.

Melt Flow Index (MFI) or I is measured on a Goettfert MI-4 melt indexer according to ASTM 1238-13₂. The test conditions were set at 190 ℃ and a 2.16kg load. Samples in amounts of 5g to 6g were loaded into the instrument barrel at 190 ℃ and manually compressed. Thereafter, the material is automatically compacted in the barrel by lowering all available weight onto the piston to remove all air bubbles. Data acquisition was started after 6 minutes of pre-melt time. Likewise, the sample was extruded through a die of 8mm length and 2.095mm diameter.

As used herein, the terms "machine direction" and "MD" refer to the direction of stretching in the plane of the film.

As used herein, the terms "transverse direction" and "TD" refer to the perpendicular direction in the plane of the film relative to the MD.

As used herein, the term "extrusion" and grammatical variations thereof is meant to include processes that form a polymer and/or polymer blend into a melt, e.g., by heating and/or shear forces, and then force the melt out of a die, e.g., in the form or shape of a film. Most any type of equipment will be suitable for carrying out the extrusion, such as single or twin screw extruders, or other melt blending devices known in the art and which may be equipped with suitable dies.

The film thickness of the film was measured by ASTM D6988-13.

The 1% secant modulus and tensile properties were determined by ASTM D882-10 using the following changes, including yield strength, elongation at yield, tensile strength and elongation at break: a 5 inch clamp was used for separation and a 1 inch sample width. The stiffness index of the film was determined by manually loosely loading the sample and pulling the sample to a specified strain of 1% of its original length at a 0.5 inch/minute grip separation rate (cross-head speed) and recording the load at these points.

The calculation procedure was as follows:

tensile strength is calculated as a function of the maximum force in pounds divided by the cross-sectional area of the specimen. Ultimate elongation is the maximum force per cross-sectional area.

The yield strength is calculated as a function of the force at yield divided by the cross-sectional area of the specimen. Yield strength is yield force per cross-sectional area.

The elongation is calculated as a function of the increase in length divided by the original length multiplied by 100. Elongation-length increase/original length x 100%.

The yield point is the first point where strain (elongation) increases and stress does not increase (force). Yield was determined by the 2% offset method.

The tensile at 100% elongation is calculated as a function of the force at 100% elongation divided by the cross-sectional area of the specimen. The elongation at 100% elongation is the force/cross-sectional area at 100% elongation.

The tensile at 200% elongation is calculated as a function of the force at 200% elongation divided by the cross-sectional area of the specimen. The elongation at 200% elongation is the force/cross-sectional area at 200% elongation.

The 1% secant modulus measures material stiffness and is calculated as a function of the total force at 1% elongation divided by the cross-sectional area multiplied by 100 and reported in PSI units. 1% secant modulus is the load at 1% elongation/(average thickness (in) x width) x 100.

Clarity is determined by ASTM D1746-15.

Haze is measured by ASTM D1003-13.

Gloss is measured by ASTM D2457-13.

Dart impact is determined by phenolic resin method A according to ASTM D1709-16ae 1.

Puncture properties were determined by ASTM D5748 using the following modifications, including peak force, peak force/mil, energy to break, and energy to break/mil. Any film sample 1mil thick was placed in an approximately 4 inch wide ring clamp. The stainless steel was custom plunger/probe with 3/4 "tip and two 0.25mil slides pressed through the sample at a constant speed of 10 in/min. Results were obtained after failure at five different locations selected from a standard film strip and the average calculated.

As used herein, the measurement per mil is calculated by dividing the measurement by the thickness value of the film. For example, a 2mil film having a peak force of 50 pounds has a peak force/mil of 25 pounds/mil.

Shrinkage (in both Machine Direction (MD) and Transverse Direction (TD)) was measured as the percent reduction in length of a 100cm circular film along the MD and TD under a heat gun (model HG-501A) set at an average temperature of 750 ° F (399 ℃). The heat gun was centered two inches above the sample and heat was applied until each specimen stopped shrinking.

Water Vapor Transmission Rate (WVTR) was performed at 100 ° F (37.8 ℃) and 100% relative humidity using ASTM F1249 on MOCON Permatran W-700 and W3/61 obtained from MOCON, inc, where the samples were loaded without specific orientation.

Polyethylene synthesis

For the purposes of the present invention and its claims, a new numbering scheme of the periodic table of the elements is used as described in Chemical and Engineering News, volume 63(5), page 27 (1985). Thus, a "group 4 metal" is an element from group 4 of the periodic table, such as Hf, Ti or Zr.

The terms "hydrocarbyl radical", "hydrocarbyl group", or "hydrocarbyl" are used interchangeably and are defined to mean a group consisting only of hydrogen and carbon atoms. Preferred hydrocarbyl is C₁-C₁₀₀A group, which may be linear, branched or cyclic, and when cyclic may be aromatic or non-aromatic. Examples of such groups include, but are not limited to, alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, octyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, and the like, aryl groups such as phenyl, benzyl, naphthyl, and the like.

A "metallocene" catalyst compound is a transition metal catalyst compound having one, two or three, typically one or two, substituted or unsubstituted cyclopentadienyl ligands bonded to a transition metal, typically a metallocene catalyst is an organometallic compound containing two pi-bonded cyclopentadienyl moieties (or substituted cyclopentadienyl moieties).

Substituted or unsubstituted cyclopentadienyl ligands include substituted or unsubstituted cyclopentadienyl, indenyl, fluorenyl, tetrahydro-s-indacenyl, tetrahydro-as-indacenyl, benzo [ f ] indenyl, benzo [ e ] indenyl, tetrahydrocyclopenta [ b ] naphthalene, tetrahydrocyclopenta [ a ] naphthalene, and the like.

Unless otherwise indicated (e.g., the definition of "substituted hydrocarbyl", etc.), the term "substituted" means that at least one hydrogen atom has been replaced with at least one non-hydrogen group, e.g., a hydrocarbyl group, a heteroatom, or a heteroatom-containing group, such as a halogen (e.g., Br, Cl, F, or I) or at least one functional group, such as — NR₂、-OR*、-SeR*、-TeR*、-PR*₂、-AsR*₂、-SbR*₂、-SR*、-BR*₂、-S iR*₃、-GeR*₃、-SnR*₃、-PbR*₃、-(CH₂)_q-SiR*₃Alternatively, wherein q is 1 to 10 and each R is independently hydrogen, a hydrocarbyl group or a halogenated hydrocarbyl group, and two or more R may be joined together to form a substituted or unsubstituted fully saturated, partially unsaturated and/or aromatic cyclic or polycyclic ring structure, or wherein at least one heteroatom has been inserted within the hydrocarbyl ring.

The term "substituted hydrocarbyl" means a hydrocarbyl group in which at least one hydrogen atom of the hydrocarbyl group has been replaced with at least one heteroatom (e.g., a halogen such as Br, Cl, F, or I) or heteroatom-containing group (e.g., a functional group such as-NR)₂、-OR*、-SeR*、-TeR*、-PR*₂、-AsR*₂、-SbR*₂、-SR*、-BR*₂、-SiR*₃、-GeR*₃、-SnR*₃、-PbR*₃、-(CH₂)_q-SiR*₃Etc., wherein q is 1 to 10 and each R is independently a hydrogen, a hydrocarbyl or a halogenated hydrocarbyl group, and two or more R may be joined together to form a substituted or unsubstituted fully saturated, partially unsaturated and/or aromatic cyclic or polycyclic ring structure), or wherein at least one heteroatom is inserted within the hydrocarbyl ring.

For the purposes of this disclosure, with respect to metallocene compounds, the term "substituted" means that the hydrogen atom has been replaced with a hydrocarbyl group, a heteroatom, or a heteroatom-containing group, such as a halogen (e.g., Br, Cl, F, or I) or at least one functional group such as — NR₂、-OR*、-SeR*、-TeR*、-PR*₂、-AsR*₂、-SbR*₂、-SR*、-BR*₂、-SiR*₃、-GeR*₃、-SnR*₃、-PbR*₃、-(CH₂)_q-SiR*₃Instead, where q is 1 to 10 and each R is independently hydrogen, a hydrocarbyl group, or a halogenated hydrocarbyl group, and two or more R may be joined together to form a substituted or unsubstituted fully saturated, partially unsaturated, and/or aromatic cyclic or polycyclic ring structure, or where at least one heteroatom has been inserted within the hydrocarbyl ring.

The inventive ethylene-based copolymers useful herein are preferably made in a process comprising: in the presence of a metallocene catalyst systemReacting ethylene and one or more C₃-C₂₀The olefin is contacted in at least one gas phase reactor at a temperature in the range of from 60 ℃ to 90 ℃ and a reactor pressure of from 70kPa to 7,000 kPa.

Preferred metallocene catalyst systems include an activator and a bridged metallocene compound.

Particularly useful bridged metallocene compounds include those represented by the formula:

wherein:

m is a group 4 metal, especially zirconium or hafnium;

t is a group 14 atom, preferably Si or C;

d is hydrogen, methyl, or a substituted or unsubstituted aryl group, most preferably phenyl;

R^aand R^bIndependently hydrogen, halogen or C₁-C₂₀A substituted or unsubstituted hydrocarbyl group, and R^aAnd R^bMay form a ring structure comprising a substituted or unsubstituted aromatic, partially saturated and/or saturated cyclic or fused ring system;

each X¹And X²Is independently selected from C₁-C₂₀Substituted or unsubstituted hydrocarbyl groups, hydride groups, amine groups, amines, alkoxy groups, thio groups, phosphido groups, halo groups, dienes, phosphines, and ethers, and X¹And X²May form a ring structure comprising an aromatic, partially saturated and/or saturated cyclic or fused ring system;

R¹、R²、R³、R⁴and R⁵Each of which is independently hydrogen, halo, alkoxy or C₁To C₂₀Or C₄₀A substituted or unsubstituted hydrocarbyl group, and any adjacent R²、R³、R⁴And/or R⁵The groups may form fused rings or multicenter fused ring systems, wherein the rings may be substituted or unsubstituted and may be aromatic, partially unsaturated and/or unsaturated; and

R⁶、R⁷、R⁸and R⁹Each independently of the other is hydrogen or C₁To C₂₀Or C₄₀A substituted or unsubstituted hydrocarbyl group, most preferably methyl, ethyl or propyl; and

further provided that R⁶、R⁷、R⁸And R⁹At least two of which are C₁-C₄₀A substituted or unsubstituted hydrocarbyl group; wherein "hydrocarbyl" (or "unsubstituted hydrocarbyl") refers to a carbon-hydrogen group such as methyl, phenyl, isopropyl, naphthyl, and the like (aliphatic, cyclic, and aromatic compounds consisting of carbon and hydrogen), and "substituted hydrocarbyl" refers to a hydrocarbyl group having at least one heteroatom bonded thereto, such as carboxyl, methoxy, phenoxy, BrCH₃—、NH₂CH₃-and so on.

Preferred metallocene compounds may be represented by the formula:

wherein R is¹、R²、R³、R⁴、R⁵、R⁶、R⁷、R⁸、R⁹、R^a、R^b、X¹、X²T and M are as defined above; and R¹⁰、R¹¹、R¹²、R¹³And R¹⁴Each independently is H or C¹-C⁴⁰Substituted or unsubstituted hydrocarbyl.

Particularly preferred metallocene compounds useful herein are represented by the formula:

wherein R is¹、R²、R³、R⁴、R5、R^a、R^b、X¹、X²T, D and M are as defined above.

In particularly preferred embodiments, the metallocene compounds useful herein may be represented by the formula:

wherein R is¹、R²、R³、R⁴、R⁵、R^a、R^b、X¹、X²T and M are as defined above. In useful embodiments, R¹、R²、R³、R⁴And R⁵Is hydrogen, and R^a、R^b、X¹、X²T and M are as defined above.

Examples of preferred metallocene compounds include: dimethylsilylene (3-phenyl-1-indenyl) (2,3,4, 5-tetramethyl-1-cyclopentadienyl) zirconium dichloride; dimethylsilylene (3-phenyl-1-indenyl) (2,3,4, 5-tetramethyl-1-cyclopentadienyl) methylzirconium; bis (n-propylcyclopentadienyl) dimethyl Hf bis (n-propylcyclopentadienyl) dichloride Hf and the like.

In a preferred embodiment, the metallocene compound is dimethylsilylene (3-phenyl-1-indenyl) (2,3,4, 5-tetramethyl-1-cyclopentadienyl) zirconium dichloride.

The polymerization process of the present invention may be carried out using any suitable process, such as solution, slurry, high pressure and gas phase. A particularly desirable process for producing the polyolefin polymers according to the present invention is a gas phase polymerization process preferably using a fluidized bed reactor. Desirably, the gas phase polymerization process is such that the polymerization medium is mechanically agitated or fluidized by the continuous flow of gaseous monomer and diluent. Other gas phase processes contemplated by the process of the present invention include tandem or multi-stage polymerization processes.

The metallocene catalyst is used with an activator in a polymerization process to produce the polyethylene of the present invention. The term "activator" as used herein is any compound that can activate any of the catalyst compounds described above by converting a neutral catalyst compound into a catalytically active metallocene compound cation. Preferably, the catalyst system comprises an activator. Activators useful herein include alumoxanes or "non-coordinating anion" activators such as boron-based compounds (e.g., tris (perfluorophenyl) borane or ammonium tetrakis (pentafluorophenyl) borate).

The catalyst systems useful herein can include at least one non-coordinating anion (NCA) activator, such as an NCA activator represented by the formula:

Z_d ⁺(A^d-)

wherein: z is (L-H) or a reducible Lewis acid; l is a neutral lewis base; h is hydrogen;

(L-H) is a Bronsted acid; a. the^d-Is a boron-containing non-coordinating anion having a charge d-; d is 1,2 or 3.

Cationic component Z_d ⁺Bronsted acids such as protic or protonated Lewis bases or reducible Lewis acids capable of protonating or abstracting moieties such as alkyl or aryl groups from transition metal catalyst precursors containing bulky ligand metallocenes to produce cationic transition metal species may be included.

Activating cation Z_d ⁺It may also be a moiety such as silver, android

Carbon (C)

Ferrocene

And mixtures, preferably carbon

And ferrocene

. Most preferably, Z_d ⁺Is a triphenyl carbon

. The preferred reducible Lewis acid may be any triaryl carbon

(wherein aryl may be substituted or unsubstituted, e.g., represented by the formula (Ar)₃C⁺) Those represented, wherein Ar is aryl or substituted by hetero atom, C₁-C₄₀Hydrocarbyl or substituted C₁-C₄₀Hydrocarbyl-substituted aryl), preferably a reducible Lewis acid of formula (14) above, e.g., "Z", is encompassed by the formula (Ph)₃C) Those represented, wherein Ph is substituted or unsubstituted phenyl, preferably substituted with C₁-C₄₀Hydrocarbyl or substituted C₁-C₄₀Hydrocarbyl, preferably C₁-C₂₀Alkyl or aromatic compounds or substituted C₁-C₂₀Alkyl or aromatic compounds, preferably Z is a triphenylcarb

。

When Z is_d ⁺Is an activating cation (L-H)_d ⁺When it is preferably a Bronsted acid, capable of donating a proton to the transition metal catalytic precursor, thereby generating transition metal cations, including ammonium, oxygen

、

Monosilane

And mixtures thereof, preferably methylamine, anilinium, dimethylamine, diethylamine, N-methylanilinium, diphenylamine, trimethylamine, triethylamine, N-dimethylaniline, methyldiphenylamine, pyridine, p-bromo-N, N-dimethylaniline, p-nitro-N, N-dimethylaniline, the ammonium salts from triethylphosphine, triphenylphosphine and diphenylphosphine

Oxygen from ethers such as dimethyl ether, diethyl ether, tetrahydrofuran and dioxane

Sulfonium from sulfides such as diethylsulfide, tetrahydrothiophene, and mixtures thereof.

Anionic component A^d-Comprises a formula [ M^k+Q_n]^d-Wherein k is 1,2 or 3; n is 1,2, 3,4,5 or 6 (preferably 1,2, 3 or 4); n-k ═ d; m is an element selected from group 13 of the periodic table of the elements, preferably boron or aluminum, and Q is independently a hydrogen radical, a bridged or unbridged dialkylamino group, halo group, alkoxy group, aryloxy group, hydrocarbyl group, substituted hydrocarbyl group, halohydrocarbyl group, substituted halohydrocarbyl group, and halogen-substituted hydrocarbyl group, said Q having up to 20 carbon atoms, with the proviso that Q is halo in no more than 1 occurrence. Preferably, each Q is a fluorinated hydrocarbyl group having 1-20 carbon atoms, more preferably each Q is a fluorinated aryl group, and most preferably each Q is a pentafluoroaryl group. Suitably A^d-Also included are diboron compounds as disclosed in U.S. patent No. 5,447,895, which is incorporated herein by reference in its entirety.

Illustrative, but non-limiting examples of boron compounds that may be used as activating cocatalysts are the compounds described as (and particularly those specifically enumerated as) activators in US 8,658,556, which is incorporated herein by reference.

Most preferably, the activator Z_d ⁺(A^d-) Is one or more of the following: n, N-dimethylanilinium tetrakis (perfluorophenyl) borate, N-dimethylanilinium tetrakis (perfluoronaphthyl) borate, N-dimethylanilinium tetrakis (perfluorobiphenyl) borate, N-dimethylanilinium tetrakis (3, 5-bis (trifluoromethyl) phenyl) borate, triphenylcarbenium tetrakis (perfluoronaphthyl) borate

Triphenylcarbenium tetrakis (perfluorobiphenyl) borate

Triphenylcarbenium tetrakis (3, 5-bis (trifluoromethyl) phenyl) borate

Or triphenylcarbenium tetrakis (perfluorophenyl) borate

。

Alternatively, preferred activators may include alumoxane compounds (or "alumoxanes") and modified alumoxane compounds. The aluminoxane is usually a compound containing-Al (R)¹) -oligomer compounds of O-subunits, wherein R¹Is an alkyl group. Examples of aluminoxanes include Methylaluminoxane (MAO), Modified Methylaluminoxane (MMAO), ethylaluminoxane, isobutylaluminoxane, and mixtures thereof. Alkylalumoxanes and modified alkylalumoxanes are suitable as catalyst activators, especially when the abstractable ligand is an alkyl, halogen, alkoxy or amino group. Mixtures of different aluminoxanes and modified aluminoxanes may also be used. Visually clear methylaluminoxane may preferably be used. The cloudy or gelled aluminoxane can be filtered to produce a clear solution or the clear aluminoxane can be decanted from the cloudy solution. Another useful aluminoxane is Modified Methylaluminoxane (MMAO) cocatalyst type 3A (commercially available from Akzo Chemicals, inc. under the trade name Modified methylaluminoxane type 3A, disclosed in US 5,041,584). Preferably, the activator is an alkylaluminoxane, preferably methylaluminoxane or isobutylaluminoxane, most preferably methylaluminoxane, according to the invention.

Preferably, the activator is supported on the support material prior to contacting with the metallocene compound. In addition, the activator may be combined with the metallocene compound prior to being disposed on the support material. Preferably, the activator may be combined with the metallocene compound in the absence of a support material.

As a complement to the activator compound, a co-activator may be used. The aluminum alkyl or organometallic compounds that may be used as cocatalysts (or scavengers) include, for example, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, dibutyl zinc, diethyl zinc, and the like.

Preferably, the catalyst system comprises an inert support material. Preferably, the supported material is a porous support material such as talc and inorganic oxides. Other support materials include zeolites, clays, organoclays or any other organic or inorganic support material, or mixtures thereof.

Preferably, the support material is an inorganic oxide in a finely divided form. Suitable inorganic oxide materials for use in the metallocene compounds herein include group 2,4, 13 and 14 metal oxides such as silica, alumina and mixtures thereof. Other inorganic oxides that may be employed alone or in combination with the silica or alumina are magnesia, titania, zirconia, and the like. However, other suitable support materials may be employed, such as finely divided functionalised polyolefins, for example finely divided polyethylene. Particularly useful supports include magnesia, titania, zirconia, montmorillonite, phyllosilicate, zeolite, talc, clay, and the like. In addition, combinations of these support materials may be used, such as silica-chromium, silica-alumina, silica-titania, and the like. Preferred support materials include Al₂O₃、ZrO₂、SiO₂And combinations thereof, more preferably SiO₂、Al₂O₃Or SiO₂/Al₂O₃。

The supported catalyst system may be suspended in a paraffinic reagent, such as mineral oil. Processes and catalyst compounds useful for preparing polyethylenes useful herein are further described in US9,266,977, US9,068,033, US 6,225,426, and US 2018/0237554, which are all incorporated herein by reference.

Polyethylene

The polyethylene may be an ethylene homopolymer or an ethylene copolymer, such as an ethylene-alpha-olefin (preferably C)₃-C₂₀Alpha-olefin) copolymer (e.g., ethylene-butene copolymer, ethylene-hexene copolymer and/or ethylene-octene copolymer) having an Mw/Mn of 5 or more (preferably 5 to 10). Unless otherwise specified, the term "polyethylene" encompassesEthylene homopolymers and ethylene copolymers.

The comonomer content of the polyethylene (if more than one comonomer is used cumulatively) can be 0 mol% (i.e., homopolymer) to 25 mol% (or 0.5 mol% to 20 mol%, or 1 mol% to 15 mol%, or 3 mol% to 10 mol%, or 6 to 10 mol%) with the balance being ethylene. Thus, the ethylene content of the polyethylene can be 75 mol% or more ethylene (or 75 mol% to 100 mol%, or 80 mol% to 99.5 mol%, or 85 mol% to 99 mol%, or 90 mol% to 97 mol%, or 4 to 90 mol%).

Alternatively, the comonomer content in the polyethylene (if cumulatively more than one comonomer is used) can be from 0 wt% (i.e., homopolymer) to 25 wt% (or from 0.5 wt% to 20 wt%, or from 1 wt% to 15 wt%, or from 3 wt% to 10 wt%, or from 6 to 10 wt%) and the ethylene content of the polyethylene can be 75 wt% or more ethylene (or from 75 wt% to 100 wt%, or from 80 wt% to 99.5 wt%, or from 85 wt% to 99 wt%, or from 90 wt% to 97 wt%, or from 4 to 90 wt%). In a preferred embodiment, the comonomer is present at 6 to 10% by weight and is preferably C₃-C₁₂An alpha-olefin (preferably one or more of propylene, butene, hexene and octene).

The comonomer may be one or more C₃-C₂₀Olefin comonomer (preferably C)₃-C₁₂An alpha-olefin; more preferably propene, butene, hexene, octene, decene and/or dodecene; most preferably propylene, butene, hexene and/or octene). Preferably, the monomer is ethylene and the comonomer is hexene, preferably 1 mol% to 15 mol% hexene, or 1 mol% to 10 mol% hexene, or 5 mol% to 15 mol% hexene, or 7 mol% to 11 mol% hexene.

The polyethylene used in the film of the present disclosure may have:

(A) melt index I₂1.0g/10min or more (or 1.5 to 5g/10min, or 1.8 to 4g/10min, or 1.9 to 3g/10 min);

(B) the density is 0.925g/cm³To 0.945g/cm³(0.927g/cm³To 0.942g/cm³Or 0.93g/cm³To 0.941g/cm³Or 0.931g/cm³To 0.94g/cm³)；

(C)g'_LCBLess than 0.8 (or 0.78-0.5, or 0.75-0.5);

(D) mz is 1,000,000g/mol or more, or 1,200,000g/mol or more, or 1,300,000g/mol or more, or 1,200,000 to 3,000,000 g/mol;

(E) Mw/Mn is 5 or greater, alternatively 5.5 to 10;

(F) mw is 100,000g/mol or greater, or 120,000g/mol or greater, or 130,000g/mol or greater, or 140,000g/mol or greater, e.g., 100,000 to 200,000g/mol, or 130,000 and 155,000 g/mol;

(G)g'_LCBand g'_ZaveThe ratio of the two is greater than 1.0, or 1.5-10, or 2.0-5; and

(H) a strain hardening ratio of 4 or greater, such as 4.5 or greater, such as 5.0 or greater, such as 6 or greater, such as 6.5 to 10, preferably wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop of 250g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

The polyethylene used in the film of the present disclosure may have:

(A) melt index I₂Is 1.0g/10min or greater (or 1.5 to 5g/10min, or 1.8 to 4g/10min, or 1.9 to 3g/10 min);

(C)g'_LCBLess than 0.8 (or 0.78-0.5, or 0.75-0.5);

(D) mz is 1,000,000g/mol or more, preferably 1,200,000g/mol or more, or 1,300,000g/mol or more, or 1,200,000 to 3,000,000 g/mol;

(E) an Mw/Mn of 5 or more, or 5.5 to 10;

(G)g'_LCBand g'_ZaveThe ratio of the two is greater than 1.0, or 1.5-10, or 2.0-5;

(H) a strain hardening ratio of 4 or more, such as 4.5 or more, such as 5.0 or more, such as 6 or more, such as 6.5 to 10; and

one, two, three, four or five of the following:

(I) a DST of 0.85 to 0.95 (or 0.86 to 0.90, or 0.87),

(K) a melting temperature of 122 ℃ or more (or 122 ℃ to 127 ℃, or 123 ℃ to 125 ℃),

(L) a crystallization temperature of 110 ℃ or more (or 110 ℃ to 115 ℃, or 110 ℃ to 113 ℃),

(M) a heat of fusion (Hf) of from about 100 to about 175J/g, and

(N) at least 7 ℃ (alternatively at least 10 ℃, alternatively at least 15 ℃) between the transition origin and the melting peak, as shown in the DSC trace.

Further, the polyethylene used in the films of the present disclosure (including any of the foregoing) can have an Mz-LS/Mn-LS of 15 or greater, or 20 or greater.

Further, the polyethylene used in the films of the present disclosure (including any of the foregoing) can have an Mz-LS/Mw-LS of 6 or greater, or 8 or greater, or 10 or greater.

In a preferred embodiment, the polyethylene described herein has at least 7 ℃ (alternatively at least 10 ℃, alternatively at least 15 ℃) between the transition origin and the melting peak, as shown in the DSC trace.

In a preferred embodiment, the polyethylene described herein has at least 10 ℃ (alternatively at least 15 ℃, alternatively at least 20 ℃) between the melting peak and the crystallization peak.

Blends

In another embodiment, the polyethylene composition produced herein is combined with one or more additional polymers in a blend prior to being formed into a film. As used herein, "blend" may refer to a dry or extruder blend of two or more different polymers, and an in-reactor blend, including blends resulting from the use of multiple catalyst systems or mixed catalyst systems in a single reactor zone, and blends resulting from the use of one or more catalysts in one or more reactors under the same or different conditions (e.g., blends resulting from each of series reactors (the same or different) operating under different conditions and/or with different catalysts).

Additional polymers that may be used include other polyethylenes, isotactic polypropylenes, highly isotactic polypropylenes, syndiotactic polypropylenes, random copolymers of propylene and ethylene and/or butene and/or hexene, polybutenes, ethylene vinyl acetate, LDPE, LLDPE, HDPE, ethylene vinyl acetate, ethylene methyl acrylate, copolymers of acrylic acid, polymethyl methacrylate or any other polymer polymerizable by the high pressure free radical process, polyvinyl chloride, polybutene-1, isotactic polybutenes, ABS resins, ethylene-propylene rubbers (EPR), vulcanized EPR, EPDM, block copolymers, styrenic block copolymers, polyamides, polycarbonates, PET resins, crosslinked polyethylene, copolymers of ethylene and vinyl alcohol (EVOH), polymers of aromatic monomers such as polystyrene, poly-1 esters, polyacetals, copolymers of ethylene and vinyl alcohol (EVOH), Polyvinylidene fluoride, polyethylene glycol and/or polyisobutylene.

Membranes and methods

The polyethylene produced by the process described herein is preferably formed into a film, particularly an oriented film, for example a biaxially oriented film.

The present disclosure relates to oriented polyethylene films comprising LLDPE having improved processability while providing a good balance of properties between stiffness in the machine direction and the cross direction while providing high toughness (or impact resistance).

For example, the present invention relates to a biaxially oriented film comprising a polyethylene having:

(C)g'_LCBLess than 0.8 (or 0.78-0.5, or 0.75-0.5);

(E) an Mw/Mn of 5 or more, or 5.5 to 10;

(G)g'_LCBand g'_ZaveThe ratio is greater than 1.0, or 1.5-10, or 2.0-5;

(H) a strain hardening ratio of 4 or more, such as 4.5 or more, such as 5.0 or more, such as 6 or more, such as 6.5 to 10;

(I) at least 10 ℃ between the melting peak and the crystallization peak; and

(J) optionally, at least 7 ℃ (alternatively at least 10 ℃, alternatively at least 15 ℃) between the transition origin and the melting peak, as shown in the DSC trace;

wherein the film has (I) a 1% secant in the cross direction of 60,000psi or more (or 70,000psi to 150,000psi, or 75,000psi to 140,000psi, or 80,000psi to 130,000psi) and (II) a 1% secant in the machine direction of 50,000psi or more (or 60,000psi or more, or 75,000psi to 150,000psi, or 80,000psi to 140,000psi, or 90,000psi to 130,000psi)

Wherein the ratio of 1% secant MD/1% secant TD is 0.65 or greater, or 0.7 or greater, or 0.75 to 1, or 0.75 to 0.95, and/or

Wherein the ratio of yield strength MD/yield strength TD is 0.20 or greater, or 0.3 or greater, or 0.4 or greater, or 0.2 to 0.95, or 0.3 to 0.85, and/or

Wherein the ratio of tensile strength MD/tensile strength TD is 0.30 or greater, or 0.35 or greater, or 0.4 or greater, or 0.30 to 1.1, or 0.35 to 1.

The films described herein can also have a gloss of 60% or less, e.g., 20 to 55%.

The films described herein can also have a dart impact A of 250 to 1,350g/mil (alternatively 275 to 1,300g/mil, or 300 to 1,250 g/mil).

The films of the present disclosure are biaxially stretched in the Machine Direction (MD) and Transverse Direction (TD) and comprise the polyethylene described herein. Preferably, the film of the present disclosure comprises polyethylene in an amount of at least 90 wt.% (or 90 to 100 wt.%, or 90 to 99.9 wt.%, or 95 to 99 wt.%). Advantageously, the polyethylenes described herein do not need to be mixed with another polymer in order to achieve good processability and film properties.

In addition to polyethylene, the film may also contain additives. Examples of additives include, but are not limited to, stabilizers (such as antioxidants or other heat or light stabilizers), antistatic agents, crosslinking agents or aids, crosslinking promoters, mold release agents, adhesion promoters, plasticizers, antiblocking agents (such as oleamide, stearamide, erucamide or other derivatives with the same activity), and fillers.

Non-limiting examples of antioxidants include, but are not limited to, IRGANOX

1076 high molecular weight phenolic antioxidant (obtained from BASF), IRGAFOS

168 (tris (2, 4-di-tert-butylphenyl) phosphite, available from BASF) and tris (nonylphenyl) phosphite. A non-limiting example of a processing aid is DYNAMAR

FX-5920 (free flowing fluoropolymer-based processing additive, available from 3M).

When present, the additive amounts cumulatively can range from 0.01 wt% to 1 wt% (or 0.01 wt% to 0.1 wt%, or 0.1 wt% to 1 wt%).

A method of producing a biaxially oriented polyethylene film may comprise: producing a polymer melt comprising the polyethylene described herein; extruding a film from a polymer melt; stretching the film in the machine direction at a temperature below the melting point temperature of the polyethylene to produce a Machine Direction Oriented (MDO) polyethylene film; and stretching the MDO polyethylene film in the transverse direction to produce a biaxially oriented polyethylene film.

Stretching in the machine direction may be achieved by passing the film through a series of rollers, with the temperature and speed of the individual rollers being controlled to achieve the desired film thickness and stretch ratio for MD stretching. Typically, this series of rolls is referred to as an MDO roll or part of the MDO stage of film production. Examples of MDOs may include, but are not limited to, pre-heated rolls, various stretching stages (with or without annealing rolls between stages), one or more conditioning and annealing rolls, and one or more cooling rolls. Stretching of the film in the MDO stage is accomplished by inducing a speed differential between two or more adjacent rolls.

The stretch ratio of the MD stretch may be used to describe the degree of stretching of the film. The draw ratio is the speed of the fast roll divided by the speed of the slow roll. For example, stretching the film using an apparatus with a slow roll speed of 1m/min and a fast roll speed of 7m/min means a stretch ratio of 7 (also referred to herein as 7 times or 7 ×). The physical stretch of the film is close to, but not exactly the stretch ratio, as relaxation of the film may occur after stretching.

The larger draw ratio of MD stretching results in a thinner film with greater orientation in the MD. The stretch ratio in the machine direction may be 1x to 10x (or 3x to 7x, or 5x to 9x, or 7x to 10 x). One skilled in the art can determine without undue experimentation the appropriate temperature and roll speed for each roll in a given MDO stage of film production to produce the desired draw ratio.

Transverse stretching can be achieved by pulling the film from the edges in a tenter frame, which is a series of moving clips, as the film passes through the stretching zone of the TDO stage oven. TDO stage ovens typically have three zones: (1) a preheating zone to soften the film, (2) a stretching zone to stretch the film in the transverse direction and (3) an annealing zone where the stretched film cools and relaxes.

The stretch ratio for TD stretching can be used to describe the degree of stretching of the film using a tenter frame (as compared to the roll speed when stretching in the MD). The stretching ratio of TD stretching is the increase in the tenter width from the stretching start point to the stretching end point and is calculated as the tenter width of the end point stretching divided by the initial tenter width and may be reported as one value or a numerical multiple or a plurality of values as in the case of MD stretching. The larger draw ratio of TD stretching results in a thinner film with greater orientation in the TD. The stretch ratio in the transverse direction when stretching the polyethylene film described herein can be 1x to 12x (or 3x to 7x, or 5x to 9x, or 8x to 12 x). One skilled in the art can determine without undue experimentation the appropriate temperature and tenter operating parameters to produce the desired draw ratio in a given TDO stage of film production.

In embodiments of the present invention, the polyethylenes described herein can be stretched in the transverse and/or machine direction over a wide temperature range. For example, the polyethylene may be stretched in the machine direction at a temperature in the range of at least 3 ℃, preferably at least 6 ℃, preferably at least 7 ℃, preferably at least 8 ℃, preferably at least 10 ℃, preferably at least 12 ℃, or 3 to 20 ℃, or 5 to 15 ℃.

Likewise, the polyethylene may be stretched in the transverse direction at a temperature in the range of at least 3 ℃, at least 5 ℃, preferably at least 6 ℃, preferably at least 7 ℃, preferably at least 8 ℃, preferably at least 10 ℃, preferably at least 12 ℃, or 3-20 ℃, or 3-15 ℃, or 3-10 ℃, or 3-6 ℃.

Preferably, the film can be stretched in the transverse direction at a temperature in the range of at least 3 ℃, at least 5 ℃, preferably at least 6 ℃, preferably at least 7 ℃, preferably at least 8 ℃, preferably at least 10 ℃, preferably at least 12 ℃, or 3 to 20 ℃, or 3 to 15 ℃, or 3 to 10 ℃, or 3 to 6 ℃ without causing web tearing and generating unevenness in film thickness.

Preferably, the film can be stretched in the machine direction without web instability and large film thickness variations over a temperature range of at least 3 ℃, preferably at least 6 ℃, preferably at least 7 ℃, preferably at least 8 ℃, preferably at least 10 ℃, preferably at least 12 ℃, or 3-20 ℃, or 5-15 ℃. The wider stretching temperature range in both MD and TD allows for greater flexibility in the line speed and stretch ratio achievable when operating the machine.

The biaxially oriented polyethylene film described herein may have a thickness of 3 mils or less (or 0.1 to 3 mils, or 0.5 to 2 mils, or 0.5 to 1.5 mils, or 0.5 to 1 mil).

The biaxially oriented polyethylene films described herein can have (i) a 1% secant in the cross direction of 60,000psi or greater (alternatively 70,000psi to 150,000psi, alternatively 75,000psi to 140,000psi, or alternatively 80,000psi to 130,000psi) and (ii) a dart drop impact a of 250g/mil to 1,350g/mil (alternatively 275g/mil to 1,300g/mil, or 300g/mil to 1,250 g/mil).

The biaxially oriented polyethylene film described herein may have (I) a 1% secant in the cross direction of 60,000psi or greater (or 70,000psi or greater, or 75,000psi to 150,000psi, or 80,000psi to 140,000psi, or 90,000psi to 130,000psi), (II) a 1% secant in the machine direction of 50,000psi or greater (or 60,000psi or greater, or 75,000psi to 150,000psi, or 80,000psi to 140,000psi, or 90,000psi to 130,000psi) and (III) a ratio of 1% secant MD/1% secant TD of 0.65 or greater, or 0.7 greater, or 0.75 or greater, or 0.75 to 1, or 0.75 to 0.95.

The biaxially oriented polyethylene film described herein may have the above (I), (II) and (III) and one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi (or 2,200psi to 4,000psi) and a yield strength in the cross direction of 4,000psi to 15,000psi (or 5,000psi to 11,000psi),

(V) a tensile strength in the machine direction of 6,000psi to 15,000psi (or 7,500psi to 14,500psi, or 8,000psi to 11,000psi) and a tensile strength in the transverse direction of 10,000psi to 30,000psi (or 11,000psi to 25,000psi, or 12,000psi to 20,000psi),

(VI) a peak force/mil of 10 to 40lbs/mil (or 12 to 35lbs/mil, or 15 to 25lbs/mil), and

(VII) a dart impact A of from 250g to 1,350g (or 275g to 1,300g, or 300g to 1,250 g).

Preferably, the biaxially oriented polyethylene film described herein has (I) and (II) and one or more of the following properties: (III), (IV), (V) and (VII). Preferably, the biaxially oriented polyethylene film described herein has (I) and (II) and one or more of the following properties: (IV) and (V).

The biaxially oriented polyethylene film described herein may have one or more of (I) and (II), (III) - (VIII) and one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³(0.927g/cm³To 0.942g/cm³Or 0.93g/cm³To 0.941g/cm³Or 0.931g/cm³To 0.94g/cm³)，

(X) an elongation at yield of 5% to 15% (or 6% to 10%) in the longitudinal direction and an elongation at yield of 9% to 17% (or 10% to 15%) in the transverse direction,

(XI) an elongation at break in the machine direction of 140% to 250% (or 150% to 240%, or 160% to 230%) and an elongation at break in the transverse direction of 30% to 120% (or 40% to 110%, or 50% to 100%),

(XII) haze of 5% to 35% (or 10% to 31%),

(XIII) transparency of 30% to 80% (or 45% to 75%), and

(IX) a fracture energy of 5 to 25 lbs. in (or 7 to 25, or 9 to 15 lbs. in) and/or a fracture energy/mil of 5 to 19 lbs. in/mil (or 6 to 18, or 9 to 16 lbs. in/mil).

Preferably, the biaxially oriented polyethylene film described herein has one or more of (I) and (II), (III) - (VIII) and one or more of the following properties: (IX), (X), (XI), (XII) and (XIII).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have a yield strength in the machine direction of from 2,000psi to 5,000psi (or 2,200psi to 4,000psi) and a yield strength in the cross direction of from 4,000psi to 15,000psi (or 5,000psi to 11,000psi) and a ratio of yield strength MD/yield strength TD of 0.20 or greater, or 0.3 or greater, or 0.4 or greater, or 0.2 to 0.95, or 0.3 to 0.85.

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have a tensile strength in the machine direction of from 6,000psi to 15,000psi (or from 7,500psi to 14,500psi, or from 8,000psi to 11,000psi) and a tensile strength in the transverse direction of from 10,000psi to 30,000psi (or from 11,000psi to 25,000psi, or from 12,000psi to 20,000psi) and a ratio of tensile strength MD/tensile strength TD of 0.30 or more, or 0.35 or more, or 0.4 or more, or 0.30 to 1.1, or 0.35 to 1.

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have a shrink in the machine direction of from 50% to 75% (or from 55% to 70%) and a shrink in the cross direction of from 60% to 90% (or from 70% to 87%, or from 72% to 83%).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have a peak force/mil from 10 to 40lbs/mil (or from 12 to 35lbs/mil, or from 15 to 25 lbs/mil).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein can have a dart drop impact a of from 250g to 1,350g (or 275g to 1,300g, or 300g to 1,250g) and/or a dart drop impact a of from 250g/mil to 1,350g/mil (or 275g/mil to 1,300g/mil, or 300g/mil to 1,250 g/mil).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have an average density of 0.925g/cm³To 0.945g/cm³(0.927g/cm³To 0.942g/cm³Or 0.93g/cm³To 0.941g/cm³Or 0.931g/cm³To 0.94g/cm³)。

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have an elongation at yield in the machine direction of 5% to 15% (or 6% to 10%) and an elongation at yield in the cross direction of 9% to 17% (or 10% to 15%).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have an elongation at break in the machine direction of from 140% to 250% (or from 150% to 240%, or from 160% to 230%) and an elongation at break in the transverse direction of from 30% to 120% (or from 40% to 110%, or from 50% to 100%).

In any embodiment herein, the biaxially oriented polyethylene film described herein may have a haze of from 5% to 35% (or from 10% to 31%).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein may have a transparency of from 30% to 80% (or from 45% to 75%).

In any of the embodiments herein, the biaxially oriented polyethylene film described herein can have an energy to break of from 5 to 25 lbs. in (or from 7 to 25 lbs. in, or from 9 to 15 lbs. in) and/or an energy to break/mil of from 5 to 19 lbs. in/mil (or from 6 to 18 lbs. in/mil, or from 9 to 16 lbs. in/mil).

End use

The biaxially oriented polyethylene film described herein may be used as a monolayer film or as one or more layers of a multilayer film. Examples of other layers include, but are not limited to, unstretched polymer films of polymers such as polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polyamide, and the like, MDO polymer films, and other biaxially oriented polymer films.

Specific end-use films include, for example, blown films, cast films, stretched/cast films, stretch cling films, stretch hand wrap films, machine stretch wrap films, shrink wrap films, greenhouse films, laminates, and laminated films. Exemplary films are prepared by any conventional technique known to those skilled in the art, such as techniques for preparing blown, extruded and/or cast stretch and/or shrink films, including shrink-on-shrink applications.

Biaxially oriented polyethylene films described herein (alone or as part of a multilayer film) are useful end-use applications including, but not limited to, film-based products, shrink films, cling films, stretch films, sealing films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, diaper backsheets, household wrap films (housewrap), medical packaging (e.g., medical films and Intravenous (IV) bags), industrial liners, films, and the like.

In one embodiment, a multilayer film or a film of multiple layers may be formed by methods well known in the art. The overall thickness of the multilayer film may vary based on the desired application. A total film thickness of about 5-100 μm, more typically about 10-50 μm, is suitable for most applications. One skilled in the art will appreciate that the thickness of the individual layers of the multilayer film can be adjusted based on the desired end-use properties, the resin or copolymer used, the equipment capabilities, and other factors. The materials forming each layer may be coextruded through a coextrusion feedblock and die assembly to produce a film having two or more layers adhered together but differing in composition. Coextrusion may be suitable for use in both cast film or blown film processes. Exemplary multilayer films have at least two, at least three, or at least four layers. In one embodiment, the multilayer film is comprised of five to ten layers.

To facilitate discussion of the different membrane structures, the following notation is used herein. Each layer of the film is designated as "a" or "B". When the film includes more than one a layer or more than one B layer, the a or B symbols are appended with one or more apostrophes (', ", etc.) to denote the same type of layer, which may be the same or may differ in one or more properties, such as chemical composition, density, melt index, thickness, etc. Finally, the symbols of adjacent layers are separated by slashes (/). Using this notation, a three-layer film with an inner layer disposed between two outer layers will be denoted as a/B/a'. Similarly, five layers of film of alternating layers will be denoted as A/B/A '/B'/A ". Unless otherwise indicated, the order of left to right or right to left of the layers is immaterial, as is the order of prime; for example, for the purposes described herein, an A/B membrane is equivalent to a B/A membrane, and an A/A '/B/A "membrane is equivalent to an A/B/A'/A" membrane. Similarly, the relative thicknesses of the individual film layers are indicated, where the values indicate the thickness of the individual layers relative to a total film thickness of 100 (dimensionless) and are separated by slashes; the relative thickness of an A/B/A 'film having, for example, 10 μm each of the A and A' layers and 30 μm of the B layer is shown as 20/60/20.

The thickness of each layer in the film and the total film thickness are not particularly limited, but are determined according to desired film properties. Typical film layers have a thickness of about 1 to about 1,000 μm, more typically about 5 to about 100 μm and typical films have a total thickness of about 10 to about 100 μm.

In some embodiments, and using the nomenclature described above, the present disclosure provides a multilayer film having any of the following exemplary structures: (a) two films such as A/B and B/B'; (b) three-layer films such as A/B/A ', A/A'/B, B/A/B ', and B/B'/B "; (c) four-layer membranes such as A/A '/B, A/A'/B/A ', A/A'/B/B ', A/B/A'/B ', A/B/B'/A ', B/A/A'/B ', A/B/B', B/A/B 'and B/B'; (d) five-layer membranes such as A/A '/B, A/A'/B/A '″, A/A'/B/A '/B', A/A '/B'/A ', A/B/A'/B, B/A '/B', A/A '/B/B', A/B/A '/B', A/B '/A'; and B/B '/A'; and, B/A/A '/B ', B/A/B '/A '/B ', B/A/B '/A ', A/B/B ' ″, B/A/B ' ″, B/B '/A/B ' "; and similarly structured films having six, seven, eight, nine, twenty-four, forty-eight, sixty-four, one hundred, or any other number of layers. It will be appreciated that the film has still more layers.

In any of the above embodiments, one or more a layers may be replaced by a substrate layer, such as glass, plastic, paper, metal, etc., or the entire film may be coated or laminated onto the substrate. Thus, while the discussion herein focuses on multilayer films, the films may also be used as coatings for substrates (e.g., paper, metal, glass, plastic, and other materials capable of receiving a coating).

The film may be further embossed or produced or processed according to other known film processes. The film can be tailored for a particular application by adjusting the thickness, materials, and order of the various layers, as well as the additives in the various layers or modifiers applied to the various layers.

Example embodiments

The invention also relates to:

1. a biaxially oriented polyethylene film comprising polyethylene having:

(A) melt index I₂Is 1.0g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBLess than 0.8 of the total weight of the composition,

(D) mz is 1,000,000g/mol or more,

(E) an Mw/Mn of 5 or more,

(F) mw is 100,000g/mol or more,

(G)g'_LCBand g'_ZaveA ratio of greater than 1.0, and

(H) a strain hardening ratio of 4 or more,

wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop of 250g/mil or greater, and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

2. The film of paragraph 1, wherein the film has a ratio of yield strength MD/yield strength TD of 0.20 or greater and/or the film has a ratio of tensile strength MD/tensile strength TD of 0.30 or greater.

3. The film of paragraph 1 or 2, wherein the polyethylene described herein has at least 10 ℃ between the onset of transition and the melting peak as shown in the DSC trace.

4. The film of paragraphs 1,2 or 3, wherein the polyethylene described herein has at least 10 ℃ between the melting peak and the crystallization peak.

5. The film of paragraphs 1 to 4, wherein the polyethylene is present at 90 wt.% to 100 wt.% of the biaxially oriented film.

6. The film of any of paragraphs 1 to 5, wherein the biaxially oriented film further comprises from 0.01 wt.% to 1 wt.% of the biaxially oriented film of an additive.

7. The film of any of paragraphs 1 to 6, wherein the biaxially oriented film has a thickness of from 0.1 to 3mil or less.

8. The film of any preceding paragraph, wherein the polyethylene has:

(A) melt index I₂Is 1.9 to 3g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBIs in the range of 0.78 to 0.5,

(D) mz is 1,300,000g/mol or more, and

(F) the Mw is 155,000g/mol or greater.

9. The film of any preceding paragraph, wherein the biaxially oriented film has one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi and a yield strength in the transverse direction of 4,000psi to 15,000psi,

(V) a tensile strength in the machine direction of 6,000psi to 15,000psi and a tensile strength in the transverse direction of 10,000psi to 30,000psi,

(VI) a peak force/mil of 10 to 40lbs/mil, and

(VII) Dart impact A is from 250g/mil to 1350 g/mil.

10. The film of paragraph 9, wherein the biaxially oriented film further has one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³，

(X) an elongation at yield of 5% to 15% in the longitudinal direction and 9% to 17% in the transverse direction,

(XI) an elongation at break in the machine direction of 140% to 250% and an elongation at break in the transverse direction of 30% to 120%,

(XII) haze of 5 to 35%,

(XIII) a transparency of 30 to 80%, and

(IX) a fracture energy of 5 to 25lbs in and/or a fracture energy/mil of 5 to 19lbs in/mil.

11. The film of any of paragraphs 1 to 10, wherein the biaxially oriented film has a thickness of from 0.3mil to 2 mil.

12. The film of paragraph 10 or 11, wherein the film is stretched at a stretch ratio in the machine direction of from 1 to 10 and a stretch ratio in the transverse direction of from 1 to 12.

13. The method comprises the following steps:

producing a polymer melt comprising a polyethylene having:

(A) melt index I₂Is 1.0g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBLess than 0.8 of the total weight of the composition,

(D) mz is 1,000,000g/mol or more,

(E) the Mw/Mn is 5 or more,

(F) mw is 100,000g/mol or more,

(G)g'_LCBand g'_ZaveA ratio of greater than 1.0, and

(H) a strain hardening ratio of 4 or more,

extruding a film from a polymer melt;

stretching the film in the machine direction to produce a Machine Direction Oriented (MDO) polyethylene film; and

stretching an MDO polyethylene film in a transverse direction to produce a biaxially oriented polyethylene film, wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop of 250g/mil or greater, and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

14. The method of paragraph 13, wherein the polyethylene has a ratio of yield strength MD/yield strength TD of the film of 0.20 or greater and/or a ratio of tensile strength MD/tensile strength TD of the film of 0.30 or greater.

15. The method of paragraph 13, wherein the polyethylene has at least 10 ℃ between the onset of transition and the melting peak as shown in the DSC trace.

16. The method of paragraphs 13, 14 or 15, wherein the stretching is at a stretch ratio of 1 to 10in the machine direction and wherein the stretching is at a stretch ratio of 1 to 12 in the cross direction.

17. The method of any of paragraphs 13-16, wherein the film is stretchable in the cross-machine direction without web breaks or tears in the range of 8 ℃ and stretchable in the cross-machine direction without web breaks or tears in the range of 5 ℃.

18. The process of any of paragraphs 13-17, wherein the polyethylene has:

(I) the degree of shear thinning is 0.85 to 0.95,

(J) a strain hardening ratio of 4 or more,

(K) the melting temperature is 122 c or more,

(L) a crystallization temperature of 110 ℃ or more,

(M) Mw is from 100,000g/mol to 155,000g/mol, and

(N) Mw/Mn is 5 to 10.

19. The process of any of paragraphs 13-18, wherein the polyethylene is present at 90 wt% to 100 wt% of the polymer melt.

20. The method of any of paragraphs 13-19, wherein the polymer melt further comprises 0.01 wt% to 1 wt% of the polymer melt of an additive.

21. The method of any of paragraphs 13-20, wherein the biaxially oriented film has a thickness of from 0.1 to 3 mils.

22. The method of any of paragraphs 13-21, wherein the biaxially oriented film has one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi and a yield strength in the cross direction of 5,000psi to 11,000psi,

(VI) a peak force/mil of 10 to 40lbs/mil, and

(VII) Dart impact A is from 250g/mil to 1350 g/mil.

23. The method of paragraph 18, wherein the biaxially oriented film further has one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³，

(X) an elongation at yield of 5% to 15% in the longitudinal direction and an elongation at yield of 9% to 17% in the transverse direction,

(XII) haze of 5 to 35%

(XIII) a transparency of 30 to 80%, and

(IX) a breaking energy of 5 to 25 lbs. in and/or a breaking energy/mil of 5 to 19 lbs. in/mil.

24. A polyethylene having:

(A) melt index I₂Is 1.0g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBLess than 0.8 of the total weight of the composition,

(D) mz is 1,000,000g/mol or more,

(E) an Mw/Mn of 5 or more,

(F) mw is 100,000g/mol or greater,

(G)g'_LCBand g'_ZaveA ratio of greater than 1.0, and

(H) a strain hardening ratio of 4 or more,

wherein when the polyethylene is formed into a biaxially oriented 1mil thick film, the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

25. The polyethylene of paragraph 24, further comprising when the polyethylene is formed into a biaxially oriented 1mil thick film, the film has a ratio of yield strength MD/yield strength TD of 0.20 or greater and/or the film has a ratio of tensile strength MD/tensile strength TD of 0.30 or greater.

26. The polyethylene of paragraph 24 or 25, wherein the polyethylene has:

(I) the degree of shear thinning is 0.85 to 0.95,

(J) the strain hardening ratio is 4 or more,

(K) the melting temperature is 122 c or more,

(L) a crystallization temperature of 110 ℃ or more,

(M) Mw of from 100,000g/mol to 155,000g/mol, and

(N) Mw/Mn is from 5 to 10.

The invention also relates to:

a biaxially oriented polyethylene film comprising a polyethylene having:

(A) melt index I₂Is 1.0g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBLess than 0.8 of the total weight of the composition,

(D) mz is 1,000,000g/mol or more,

(E) the Mw/Mn is 5 or more,

(F) mw is 100,000g/mol or more,

(G)g'_LCBand g'_ZaveA ratio of greater than 1.0, and

(H) the strain hardening ratio is 4 or more,

wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

The film of paragraph 1A, wherein the film has a ratio of yield strength MD/yield strength TD of 0.20 or greater and/or the film has a ratio of tensile strength MD/tensile strength TD of 0.30 or greater.

The film of paragraph 1A, wherein the polyethylene described herein has at least 10 ℃ between the onset of transition and the melting peak as shown in the DSC trace.

The film of paragraph 1A, wherein the polyethylene described herein has at least 10 ℃ between the melting peak and the crystallization peak.

The film of paragraph 1A, wherein the polyethylene is present at 90 wt% to 100 wt% of the biaxially oriented film.

The film of paragraph 1A, wherein the biaxially oriented film further comprises from 0.01 wt.% to 1 wt.% of the biaxially oriented film of an additive.

The film of paragraph 1A, wherein the biaxially oriented film has a thickness of from 0.1 to 3mil or less.

The film of paragraph 1A, wherein the polyethylene has:

(A) melt index I₂Is 1.9 to 3g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBIs in the range of 0.78 to 0.5,

(D) mz is 1,300,000g/mol or more, and

(F) the Mw is 155,000g/mol or greater.

The film of paragraph 1A, wherein the biaxially oriented film has one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi and a yield strength in the cross direction of 4,000psi to 15,000psi,

(VI) a peak force/mil of 10 to 40lbs/mil, and

(VII) Dart impact A is from 250g/mil to 1350 g/mil.

The film of paragraph 9A, wherein the biaxially oriented film further has one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³，

(XII) haze 5 to 35%

(XIII) transparency of 30 to 80%, and

The film of paragraph 1A, wherein the biaxially oriented film has a thickness of from 0.3mil to 2 mil.

The film of paragraph 10A, wherein the film is stretched at a stretch ratio in the machine direction of from 1 to 10 and the film is stretched at a stretch ratio in the transverse direction of from 1 to 12.

A method comprising:

producing a polymer melt comprising a polyethylene having:

(A) melt index I₂Is 1.0g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBLess than 0.8 of the total weight of the composition,

(D) mz is 1,000,000g/mol or more,

(E) the Mw/Mn is 5 or more,

(F) mw is 100,000g/mol or more,

(G)g'_LCBand g'_ZaveA ratio of greater than 1.0, and

(H) the strain hardening ratio is 4 or more,

extruding a film from a polymer melt;

stretching an MDO polyethylene film in a transverse direction to produce a biaxially oriented polyethylene film, wherein the film has a 1% secant in the transverse direction of 60,000psi or greater, a dart drop impact of 250g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

14a. the method of paragraph 13A, wherein the polyethylene has a ratio of yield strength MD/yield strength TD of the film of 0.20 or greater and/or a ratio of tensile strength MD/tensile strength TD of the film of 0.30 or greater.

The method of paragraph 13A, wherein the polyethylene has at least 10 ℃ between the onset of transition and the melting peak as shown in the DSC trace.

The method of paragraph 13A, wherein the stretching is in the machine direction at a stretch ratio of 1 to 10, and wherein the stretching is in the cross direction at a stretch ratio of 1 to 12.

The method of paragraph 13A, wherein the film can be stretched in the cross direction without web breaks or tears in the range of 8 ℃ and stretched in the cross direction without web breaks or tears in the range of 5 ℃.

The method of paragraph 13A, wherein the polyethylene has:

(I) the degree of shear thinning is 0.85 to 0.95,

(J) a strain hardening ratio of 4 or more,

(K) the melting temperature is 122 c or more,

(L) a crystallization temperature of 110 ℃ or more,

(M) Mw is from 100,000g/mol to 155,000g/mol, and

(N) Mw/Mn is 5 to 10.

The method of paragraph 13A, wherein the polyethylene is present at 90 wt% to 100 wt% of the polymer melt.

The method of paragraph 13A, wherein the polymer melt further comprises from 0.01 wt.% to 1 wt.% of the polymer melt of an additive.

The method of paragraph 13A, wherein the biaxially oriented film has a thickness of from 0.1 to 3 mil.

The method of paragraph 13A, wherein the biaxially oriented film has one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi and in the transverse direction of 5,000psi to 11,000psi,

(VI) a peak force/mil of 10 to 40lbs/mil, and

(VII) Dart impact A is from 250g/mil to 1350 g/mil.

The method of paragraph 18A, wherein the biaxially oriented film further has one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³，

(XII) haze 5 to 35%

(XIII) a transparency of 30 to 80%, and

Polyethylene having:

(A) melt index I₂Is 1.0g/10min or more,

(B) the density is 0.925g/cm³To 0.945g/cm³，

(C)g'_LCBLess than 0.8 of the total weight of the composition,

(D) mz is 1,000,000g/mol or more,

(E) an Mw/Mn of 5 or more,

(F) mw is 100,000g/mol or more,

(G)g'_LCBand g'_ZaveA ratio of greater than 1.0, and

(H) a strain hardening ratio of 4 or more,

The polyethylene of paragraph 24A, further comprising when the polyethylene is formed into a biaxially oriented 1mil thick film, the film has a ratio of yield strength MD/yield strength TD of 0.20 or greater and/or the film has a ratio of tensile strength MD/tensile strength TD of 0.30 or greater.

The polyethylene of paragraph 24A, wherein the polyethylene has:

(I) the degree of shear thinning is from 0.85 to 0.95,

(J) a strain hardening ratio of 4 or more,

(K) the melting temperature is 122 c or more,

(L) a crystallization temperature of 110 ℃ or more,

(M) Mw of from 100,000g/mol to 155,000g/mol, and

(N) Mw/Mn is 5 to 10.

In order to facilitate a better understanding of embodiments of the present invention, the following examples of preferred or representative embodiments are given. The following examples should in no way be construed as limiting or restricting the scope of the invention.

Experiment of

Catalyst A is Me₂Si[Me₄Cp][3-Ph-Ind]ZrCl₂Dimethylsilyl (tetramethyl-cyclopentadienyl) (3-phenylindenyl) zirconium dichloride and prepared as generally described in US9,266,977 (see metallocene 1).

₂ ₄ ₂MeSi[MeCp][3-Ph-Ind]Preparation of ZrCl supported catalyst

Preparation of Me₂Si[Me₄Cp][3-Ph-Ind]ZrCl₂Activation and loading of (2). Methylaluminoxane (MAO) in an amount of 687g (30% by weight in toluene) was added together with toluene in an amount of 1504g in a 4L stirred vessel in a drying cabinet. An amount of 15.7g of metallocene dissolved in 200mL of toluene was added. The solution was then stirred at 60rpm for 5 minutes. Another 165g amount of toluene was added. The solution was stirred at 120rpm for 30 minutes. The stirring rate was reduced to 8 rpm. Will have been calcined at 875 DEG CBurnt ES-70^TMSilica (pq corporation, Conshohocken, pa) was added to the vessel. The slurry was stirred with another 154 grams of toluene for 30 minutes for rinsing, and then dried under vacuum at room temperature for 22 hours. After emptying the vessel and sieving the supported catalyst, an amount of 763 grams was collected.

Polymerisation

The polymerization was carried out in a 22 foot high gas phase fluidized bed reactor having a 13 inch straight section internal diameter and an upper wider conical expansion section. Recycle and feed gases were fed to the reactor body through a perforated distributor plate and the reactor was controlled at 290psig and 64 mol% ethylene. The reactor temperature is controlled by manipulating the temperature of the recycle gas loop.

Catalyst as dry powder with N₂The carrier gas is fed to the reactor together. Continuous additive (CA-300 from Univation) was co-fed into the reactor through the second carrier nozzle of the reactor bed, and the feed rate of the continuous additive was adjusted to maintain the weight concentration in the bed between 20ppm and 40 ppm. Good reactor operability was observed for all conditions. The polymerization processing conditions can be seen in table a.

TABLE A

Polymer products	Product A	Product B
			Catalyst (-)	Catalyst A	Catalyst A
Bed temperature (degree F)	185.0	185.0
			Reactor pressure (psig)	289.1	290.0
Ethylene concentration (mol%)	63.8	63.9
			H₂/C₂Gas ratio (ppm/mol%)	5.60	5.28
C₆/C₂Flow rate ratio (lb/lb)	0.079	0.062
			iC₅Composition (mol%)	3.7	3.9
Settled bulk density (g/cm)³)	0.3343	0.3632
			Residence time (hr)	2.1	2.4

The polymers were characterized and the results are reported in tables 1,2 and 3.

Table 1: structural parameter of GPC4D

Table 2: DSC structural parameter

Table 3: structural and rheological parameters

Property testing procedure

Melt Index (MI) measurements (ASTM D1238) were made on a Goettfert MI-4 melt indexer. The test conditions for MI were set at 190 ℃ and 2.16kg load. A sample in an amount of-3 g was loaded into the instrument barrel at 190 ℃ and manually compressed. Thereafter, the material is automatically compacted in the barrel by lowering all available weight onto the piston to remove all air bubbles. Data acquisition was started after 6 minutes of pre-melt time. In addition, the sample was extruded through a die of 8mm length and 2.095mm diameter. The gradient density of the samples was measured according to the standard test method for plastics (ASTM D1505-10) and compression molded by testing according to ASTM D4703-10 a.

Differential Scanning Calorimetry (DSC)

DSC runs were performed using TA Instruments' Discovery 2500. The peak melting or melting temperature (Tm), peak crystallization or crystallization temperature (Tc), and heat of fusion or heat flow (Δ Hf or Hf) were determined using the following DSC procedure. Samples weighing approximately 2-5mg were carefully sealed in aluminum gas-tight pans. The heat flow was normalized by the sample mass. The DSC run was ramped from 0 deg.C to 200 deg.C at a rate of 10 deg.C/min, and after equilibration, the sample was cooled down to 0 deg.C at 10 deg.C/min. The first and second thermal cycles were recorded. The melting temperature (Tm) was calculated by integrating the melting peak (area under the curve) in the range of about 5 ℃ to about 135 ℃ (baseline).

Film production

Biaxially oriented polyethylene films were produced on a BIAX laboratory pilot line (which is a small scale variant of a commercially available production line) from Parkinson Technologies Inc. The BIAX laboratory pilot line has 5 main sections: extrusion, casting, MD, TD and winding.

Uniaxial stretching in the MD is obtained by increasing the speed between two intermediate rolls. The MD orientation section operates off-line directly from a roll stock to produce a uniaxially oriented film on heated and cooled rolls. MD orientation is coupled to a tenter frame downstream of the TD orientation stage to produce a biaxially oriented film.

In the next experiment, the BIAX lab pilot line was operated to produce unoriented cast films and combined with other sections of biaxially (MD-TD) oriented film. Furthermore, we used a single screw extruder (monolayer) and reported the main parameters in table B. The MDO stage is operated to produce a uniaxially oriented film on heated and cooled rolls. This section was connected to a TD downstream tenter frame to produce a biaxially oriented film. The MDO section was designed vertically and had six rolls with diameters of 18 "(457 mm) and 30" (762mm) face widths. The draw segment gap was set to 0.035 "(0.889 mm) and was kept constant for all biaxially oriented films. The temperature and speed are accurately and independently controlled.

Table B: extruder parameters

In the TDO stage, the film is biaxially oriented by heating a pre-stretched MDO material (hot air oven) and pulling the film from the edges along the TD in a tenter frame (a series of moving clips). The film orientation is adjusted and regulated by a pair of diverging tracks. The preheat, draw, and anneal temperatures are set at the TDO stage. The oven consists of three heated and independently controlled zones.

MDO and TDO processing conditions, including cast sheet size and line speed, are reported in table C. Further, the web was allowed to relax at about 5% per side in the annealing zone to partially remove the accumulated stress. After TDO, the film was trimmed at the edges and the film thickness was measured and then entered the winding section.

During the testing of all samples, we were able to achieve a reliable and stable production line with speeds up to 76.5 ft/min.

Table C: MDP and TDO parameters

And (3) a product: BOPE film Properties

Membrane characterization was performed on 8 samples and reported in table 4. All samples were measured along MD and TD. All samples were conditioned for 40 hours at 23 ° ± 2 ℃ and 50 ± 10% relative humidity (ASTM D618-08) prior to testing.

Note that some films have stripes in the machine and cross directions. These bands impart non-uniformity across the web and film thickness variations. Therefore, we only target the film properties of 1mil and exclude values outside the range of +/-0.2. The bands at the TDO clip may be due to necking formation (longitudinal bands). The transverse bands (in the MD) are produced downstream of the apparatus at the die orifice of the extruder.

Table 4: film Properties

Table 4: film Properties

The present invention may at first glance be similar to the concurrently filed application (related application USSN 62/945760 entitled "Biaxially organized Polyethylene Films" (attorney docket No. 2019EM494)), but noting the comparison between the USSN 62/945760 sample and the present sample in table 5 below.

Table 5: property differences between related inventions and present invention

Membrane characterization method

The film thickness of the film was measured by ASTM D6988-13.

The 1% secant modulus and tensile properties were determined by ASTM D882-10 using the following changes, including yield strength, elongation at yield, tensile strength, and elongation at break: a 5 inch grip separation and a 1 inch sample width were used. The stiffness index of the film was determined by manually loosely loading the sample and pulling the sample to a specified strain of 1% of its original length at a fixture separation rate (crosshead speed) of 0.5 inches/minute and recording the load at these points. The calculation procedure was as follows:

Yield strength is calculated as a function of the force at yield divided by the cross-sectional area of the specimen. Yield strength is yield force per cross-sectional area.

The elongation is calculated as a function of the increase in length divided by the original length multiplied by 100. Elongation is length increase/original length x 100%. The yield point is the first point where the increase in strain (elongation) is increased without an increase in stress (force). Yield was determined by the 2% offset method.

The tensile at 100% elongation is calculated as a function of the force at 100% elongation divided by the cross-sectional area of the sample. The elongation at 100% elongation is the force/cross-sectional area at 100% elongation.

The 1% secant modulus measures material stiffness and is calculated as a function of the total force at 1% elongation divided by the cross-sectional area multiplied by 100 and reported in PSI units. 1% secant modulus is load at 1% elongation/(average thickness (in) × width) × 100.

Clarity is determined by ASTM D1746-15.

Haze is determined by ASTM D1003-13.

Gloss is measured by ASTM D2457-13.

Dart impact is determined by phenolic method A according to ASTM D1709-16ae 1.

Puncture properties were determined by ASTM D5748 using the following modifications, including peak force, peak force normalized to 1mil thickness (peak force divided by thickness), energy to break, and energy to break normalized to 1mil thickness (energy to break divided by thickness). Any film sample of 1mil thickness was placed in an annular fixture approximately 4 inches wide. The stainless steel was custom plunger/probe with 3/4 "tip and two 0.25mil slides pressed through the sample at a constant speed of 10 in/min. Results were obtained after failure at five different locations selected from a standard film strip and the average was calculated.

Shrinkage (in both the Machine Direction (MD) and Transverse Direction (TD)) was measured as the percent reduction in length of a 100cm circular film along the MD and TD under a heat gun (model HG-501A) set to an average temperature of 750 ° F (399 ℃). The heat gun was centered two inches above the sample and heat was applied until each specimen stopped shrinking.

Water Vapor Transmission Rate (WVTR) tests were performed at 100 ° F (37.8 ℃) and 100% relative humidity using ASTM F1249 on MOCON Permatran W-700 and W3/61 obtained from MOCON, inc, with the samples loaded without specific orientation.

SAOS Small Amplitude Oscillatory Shear (SAOS) measurements were made on an Anton Paar MCR702 rheometer. The samples were compression molded at 177 ℃ for 15 minutes (including cooling under pressure) and 25mm test disc specimens were die cut from the resulting sheets. The test was performed using a 25mm parallel plate geometry. Amplitude scanning was performed on all samples to determine the linear deformation region. For amplitude scanning, the strain is set at 0.1-100%, with a frequency of 6rad/sec and a temperature of 190 ℃. Once linearity was established, a frequency sweep was performed to determine the complex viscosity curve. The test was run from 0.01 to 500rad/s and was performed at 5% strain at T ═ 190 ℃.

where eta (0.01rad/s) and eta (50rad/s) are complex viscosities at frequencies of 0.01 and 50rad/s, respectively, measured at 190 ℃. The DST parameters help to better distinguish and emphasize the branching characteristics of the samples. In fact, the higher the DST parameter, the higher the degree of shear thinning.

SER-A Sentmanat Extensional Rheometer (SER) test bench and transient uniaxial extensional viscosity test are described in detail in US 2018/0319907. The extensional evolution of the instantaneous extensional viscosity was studied by means of an MCR501(Anton Paar) rheometer with controlled operating speed. The Linear Viscoelastic Envelope (LVE) was obtained from a start-up steady state shear experiment.

For all samples, the draw rate was 0.1 and 10s at T ═ 150 ℃^-1The tensile stress growth showed deviation from LVE. In the nonlinear region, branched and high molecular weight polymers exhibit strain hardening curves in the tensile tack test. Strain hardening is defined as a rapid and abrupt flattening of the extensional viscosity from a linear viscoelastic behavior. This non-linear behavior is therefore quantified by the Strain Hardening Ratio (SHR), which is defined as1s^-1Maximum instantaneous elongational viscosity at time of 0.1s^-1Ratio of the respective values of (a):

0.1s^-1the values of (c) are superior to LVE because only transient stretching is selected for use in the process rather than initiating steady state shear data. When the ratio is greater than 1, the material exhibits strain hardening.

All documents described herein are incorporated by reference herein, including any priority documents and/or test procedures, as long as they are not inconsistent herewith. While forms of the invention have been illustrated and described, it will be apparent from the foregoing general description and specific embodiments that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited thereby. Likewise, the term "comprising" is considered synonymous with the term "including". Likewise, whenever a component, element or group of elements is preceded by the conjunction "comprising," it is to be understood that the recitation of a component, element or group of elements as being preceded by the conjunction "consisting essentially of," "consisting of," "selected from," or "being," the same component or group of elements is also contemplated, and vice versa.

Claims

1. A biaxially oriented polyethylene film comprising polyethylene having:

(A) melt index I₂1.0g/10min or greater;

(B) the density is 0.925g/cm³To 0.945g/cm³；

(C)g'_LCBLess than 0.8;

(D) mz is 1,000,000g/mol or more;

(E) Mw/Mn is 5 or more;

(F) mw is 100,000g/mol or greater;

(G)g'_LCBand g'_ZaveThe ratio of the ratio is more than 1.0; and

(H) the strain hardening ratio is 4 or more,

2. The film according to claim 1, wherein the film has a ratio of yield strength MD/yield strength TD of 0.20 or more and/or the film has a ratio of tensile strength MD/tensile strength TD of 0.30 or more.

3. The film according to claim 1 or 2, wherein the polyethylene described herein has at least 10 ℃ between the onset of transition and the melting peak as shown in the DSC trace.

4. The film according to claim 1,2 or 3, wherein the polyethylene described herein has at least 10 ℃ between the melting peak and the crystallization peak.

5. The film of any one of claims 1 to 4, wherein the polyethylene is present at 90 to 100 weight percent of the biaxially oriented film.

6. The film of any of claims 1 to 5, wherein the biaxially oriented film further comprises from 0.01% to 1% by weight of the biaxially oriented film of an additive.

7. The film of any one of claims 1 to 6, wherein the biaxially oriented film has a thickness of 0.1 to 3 mils or less.

8. The film according to any one of the preceding claims, wherein the polyethylene has:

(A') melt index I₂1.9 to 3g/10min or more;

(B') the density was 0.925g/cm³To 0.945g/cm³；

(C')g'_LCBFrom 0.78 to 0.5;

(D') Mz is 1,300,000g/mol or more; and

(F') Mw of 155,000g/mol or more.

9. The film of any of the preceding claims, wherein the biaxially oriented film has one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi and a yield strength in the cross direction of 4,000psi to 15,000 psi;

(V) a tensile strength in the machine direction of 6,000psi to 15,000psi and a tensile strength in the transverse direction of 10,000psi to 30,000 psi;

(VI) a peak force/mil of 10 to 40 lbs/mil; and

(VII) Dart impact A is from 250g/mil to 1350 g/mil.

10. The film of claim 9, wherein the biaxially oriented film further has one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³；

(XII) haze of 5 to 35%

(XIII) transparency of 30 to 80%, and

11. The film of any one of claims 1 to 10, wherein the biaxially oriented film has a thickness of 0.3mil to 2 mil.

12. The film of claim 10 or 11, wherein the film is stretched at a stretch ratio of 1 to 10in the machine direction and 1 to 12 in the transverse direction.

13. The method comprises the following steps:

producing a polymer melt comprising polyethylene having:

(A) melt index I₂1.0g/10min or more;

(B) the density is 0.925g/cm³To 0.945g/cm³；

(C)g'_LCBLess than 0.8;

(D) mz is 1,000,000g/mol or more;

(E) Mw/Mn is 5 or more;

(F) mw is 100,000g/mol or greater;

(G)g'_LCBand g'_ZaveThe ratio of the ratio is more than 1.0; and

(H) the strain hardening ratio is 4 or more,

extruding a film from a polymer melt;

14. The method of claim 13, wherein the polyethylene has a ratio of yield strength MD/yield strength TD of the film of 0.20 or greater and/or a ratio of tensile strength MD/tensile strength TD of the film of 0.30 or greater.

15. The process of claim 13, wherein the polyethylene has at least 10 ℃ between the onset of transition and the melting peak as shown in the DSC trace.

16. The method of claim 13, 14, or 15, wherein the stretching is at a stretch ratio of 1 to 10in the machine direction, and wherein the stretching is at a stretch ratio of 1 to 12 in the cross direction.

17. The method of any one of claims 13-16, wherein the film is stretchable in the cross direction without web breaks or tears at a temperature in the range of 8 ℃ and stretchable in the cross direction without web breaks or tears at a temperature in the range of 5 ℃.

18. The method of any one of claims 13-17, wherein the polyethylene has:

(I) the degree of shear thinning is 0.85 to 0.95,

(J) a strain hardening ratio of 4 or more,

(K) the melting temperature is 122 c or higher,

(L) a crystallization temperature of 110 ℃ or more,

(M) Mw of from 100,000g/mol to 155,000g/mol, and

(N) Mw/Mn is from 5 to 10.

19. The method of any one of claims 13-18, wherein the polyethylene is present at 90 wt% to 100 wt% of the polymer melt.

20. The method of any of claims 13-19, wherein the polymer melt further comprises from 0.01 wt% to 1 wt% of the polymer melt of an additive.

21. The method of any of claims 13-20, wherein the biaxially oriented film has a thickness of from 0.1 to 3 mils.

22. The method of any one of claims 13-21, wherein the biaxially oriented film has one or more of the following properties:

(IV) a yield strength in the machine direction of 2,000psi to 5,000psi and a yield strength in the cross direction of 5,000psi to 11,000 psi;

(V) a tensile strength in the machine direction of 6,000psi to 15,000psi and a tensile strength in the cross direction of 10,000psi to 30,000 psi;

(VI) a peak force/mil of 10 to 40 lbs/mil; and

(VII) Dart impact A is from 250g/mil to 1350 g/mil.

23. The method of claim 18, wherein the biaxially oriented film further has one or more of the following properties:

(IX) average Density of 0.925g/cm³To 0.945g/cm³；

(X) an elongation at yield of 5% to 15% in the longitudinal direction and 9% to 17% in the transverse direction;

(XI) elongation at break in the machine direction of 140% to 250% and elongation at break in the transverse direction of 30% to 120%;

(XII) haze 5% to 35%;

(XIII) transparency of 30 to 80%; and

24. A polyethylene having:

(A) melt index I₂1.0g/10min or greater;

(B) the density is 0.925g/cm³To 0.945g/cm³，；

(C)g'_LCBLess than 0.8;

(D) mz is 1,000,000g/mol or more;

(E) Mw/Mn is 5 or more;

(F) mw is 100,000g/mol or greater;

(G)g'_LCBand g'_ZaveThe ratio of the two is greater than 1.0; and

(H) the strain hardening ratio is 4 or more,

25. The polyethylene of claim 24, wherein when the polyethylene is formed into a biaxially oriented 1mil thick film, the film has a ratio of yield strength MD/yield strength TD of 0.20 or greater and/or the film has a ratio of tensile strength MD/tensile strength TD of 0.30 or greater.

26. A polyethylene according to claim 24 or 25, wherein the polyethylene has:

(I) the degree of shear thinning is 0.85 to 0.95,

(J) the strain hardening ratio is 4 or more,

(K) the melting temperature is 122 c or more,

(L) a crystallization temperature of 110 ℃ or more,

(M) Mw of from 100,000g/mol to 155,000g/mol, and

(N) Mw/Mn is 5 to 10.