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

Abstract

The present invention relates to a biaxially oriented polyethylene film comprising polyethylene having (A) a melt index I of 1.0 _g /10 min or more, (B) a density ^of 0.925 g/cm to 0.945 g/cm ³ , (C) g' _vis is less than 0.8, (D) Mz is 1,000,000 g/mol or more, (E) Mw/Mn is 5 or more, (F) Mw is 100,000 g/mol or more, ( G) a ratio of g' _LCB to g' _Zave 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 60,000 psi or greater and a dart drop of 250 g The ratio of /mil or greater and 1% secant MD/1% secant TD is 0.65 or greater.

Description

Biaxially oriented polyethylene film and method for producing the same

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of US Provisional Application No. 62/945765, filed December 9, 2020, entitled "Biaxially Oriented PolyethyleneFilms and Process for Production Thereof," which is incorporated herein by reference in its entirety.

Field of Invention

The present disclosure relates to biaxially oriented polyethylene films.

background

Films with high strength properties including tensile strength and impact toughness are required for packaging applications including food packaging and stretch wrap, shrink wrap and grocery bags. Thinner and thinner films exhibiting high strength requirements offer consumers a better cost-performance relationship. Biaxial orientation of polymer films can be used to improve strength properties while reducing film thickness.

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

Polyethylene films have recently gained interest in the field because polyethylene is easier to recycle. However, polyethylene tends to have a higher degree of crystallinity than polypropylene, making it more difficult to reduce thickness and maintain the right balance of stiffness and toughness properties.

US 9,068,033 discloses ethylene hexene copolymers, inter alia, having a _g'vis of less than 0.8, a melt index I2 of 0.25 to 1.5 g/10min, which are converted into films.

US Patent No.: US 5,955,625, US 6,168,826, US 6,225,426, US 9,266,977, EP2935367, US Patent Application Publication No. 0237559, US 2018/0237554, US 2018/0319907, US 2018/0023788, WIPO Patent Application Publication No. WO 2017/127808, WO 2015/154253, WO 2015/138096, WO 1997/022470, Japanese Patent Application Publication No. 2016/14730 Kim, W.N. et al. (1994) "Morphology and Mechanical Properties of Biaxially Oriented Films of Polypropylene and HDPE Blends," Appl. Polym. Sci., Vol. 54(11), pp. 1741-1750; Ratta, V. et al. (2001) "Structure-Property-Processing Investigations of the Tenter-Frame Process for Making Biaxially Oriented HDPE Film. I. Base Sheet and Draw Along the MD" Polymer, Vol. 42(21), pp. 9059-9071; Ajji, A. et al. (2004) "Biaxial Stretching and Structure of Various LLDPE Resins" Polym.Eng.Sci., Vol. 44(2), pp. 252-260; Ajji, A. et al. (2006) "Biaxial Orientation in LLDPE Films: Comparison of Infrared Spectroscopy, X-ray Pole Figures, and Birefringence Techniques,” Polym. Eng. Sci., Vol. 46(9), pp. 1182–1189; Uehara, H et al. (2004) “Stretchability and Properties of LLDPE Blends for Bia xially Oriented Film, "Intern. Polymer Processing, Vol. 19(2), p. 163; Bobovitch, A.L. et al. (2006) "Mechanical Properties Stress-Relaxation, and Orientation of Double Bubble Biaxially OrientedPolyethylene Films," J.Appl.Poly. Sci., Vol. 100(5), pp. 3545-3553; Sun, T. et al. (2001) Macromolecules, Vol. 34(19), pp. 6812-6820; Stadelhofer, J. et al. (1975)" Darstellung und Eigenschaften von Alkylmetallcyclo-Pentadienderivaten desAluminiums, Galliums und Indiums, "Jrnl. Organometallic Chem., Vol. 84, Pages C1-C4 and Chen, Q. et al. (2019) "Structure Evolution of Polyethylene in Sequential BiaxialStretching along the First Tensile Direction," Ind.Eng.Chem.Res., Vol. 58, pp. 12419-12430.

SUMMARY OF THE INVENTION

The present disclosure relates to biaxially oriented polyethylene films, including 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 polyethylene having (A) a melt index I ₂ of 1.0 g/10 min or more, (B) a density ^of 0.92 g/cm to 0.94 g/cm ³ , (C) g' _LCB is less than 0.8, (D) Mz is 1,000,000 g/mol or more, (E) Mw/Mn is 5 or more, (F) Mw is 100,000 g/mol or more, ( G) a ratio of g' _LCB to g' _Zave 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 60,000 psi or greater and a dart drop of 250 g The ratio of /mil or greater and 1% secant MD/1% secant TD is 0.65 or greater.

The present disclosure also relates to compositions comprising: a biaxially oriented film comprising polyethylene having (A) a melt index I ₂ of 1.0 g/10min or greater, (B) a density of 0.925g/ ^cm3 to 0.945g/ ^cm3 , (C) g' _LCB less than 0.8, (D) Mz of 1,000,000 g/mol or more, (E) Mw/Mn of 5 or more, (F) Mw is 100,000 g/mol or greater, (G) a ratio of g' _LCB to g' _Zave 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 60,000 psi or greater, dart impact of 250 g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

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

detail

The present disclosure relates to biaxially oriented polyethylene films comprising LLDPE with well-defined properties for improved 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) a melt index I ₂ of 1.0 g/10 min or more, (B) a density of 0.925 to 0.945 g ^{/cm 3 ,} (C) g ' _LCB is less than 0.8, (D) Mz is 1,000,000 g/mol or greater, (E) Mw/Mn is 5 or greater, (F) Mw is 100,000 g/mol or greater, (G) g' _LCB is The _g'Zave ratio is greater than 1.0, and the (H) strain hardening ratio is 4 or greater, wherein the film has a 1% secant in the transverse direction of 60,000 psi or greater, a dart impact of 250 g/mil or greater and 1 The ratio of %secant MD/1%secant TD is 0.65 or greater. Polyethylene can be further characterized by having (A) a melt index I ₂ of 1.5 g/10min to 5 g/10min, (B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ , (C) g' _LCB is less than 0.8 to 0.5, (D) Mz is 1,200,000 g/mol or more, (E) Mw/Mn is 5 to 10, (F) Mw is 100,000 to 200,000 g/mol, (G) g' _LCB and g ' _{The Zave} ratio is 1.5 to 10, and the (H) strain hardening ratio is 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 the toughness of thicker films produced using other LLDPEs.

Define and test methods

Room temperature is 25°C unless otherwise indicated.

An "olefin" or "alkene" as it is referred to is a linear, branched or cyclic carbon and hydrogen compound 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 monomeric units. The term "polymer" as used herein includes, but is not limited to, homopolymers, copolymers, terpolymers, and the like. The term "polymer" as used herein also includes impact, block, graft, random and alternating copolymers. Unless specifically stated otherwise, the term "polymer" shall also include all possible geometrical configurations. Such configurations may include isotactic, syndiotactic, and atactic 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 (ie, monomeric units). For example, the term "copolymer" includes the copolymerization reaction product of propylene and an alpha-olefin such as ethylene, 1-hexene. A "terpolymer" is a polymer having three monomer units that are different from each other. Thus, the term "copolymer" also includes copolymer products of terpolymers and tetrapolymers such as mixtures of ethylene, propylene, 1-hexene and 1-octene.

"Different" as used to refer to monomeric monomer units means that the monomer 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 containing at least 50 mole percent ethylene-derived units, and a "propylene polymer" or "propylene copolymer" is a polymer containing at least 50 mole percent propylene-derived units or copolymers, etc. 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 polymerized/derivative form of monomers in the polymer. For example, when a copolymer is said to have an "ethylene" content of 35% to 55% by weight, it is understood that the monomer units in the copolymer are derived from ethylene in the polymerization reaction, and that the derived units are based on the copolymerization is present at 35% to 55% by weight of the material.

"Low Density Polyethylene" LDPE is an ethylene polymer having a density of greater than 0.90 g/ ^cm3 to less than 0.94 g/ ^cm3 ; such polyethylenes include copolymers made using heterogeneous catalysis processes (often identified as low linearity density polyethylene (LLDPE) and homopolymers or copolymers prepared using high pressure/radical processes (often identified as LDPE). "Linear low density polyethylene" LLDPE is an ethylene polymer having a density of greater than 0.90 g/cm ³ to less than 0.94 g/cm ³ , preferably 0.910-0.935 g/cm ³ and typically having a g' _LCB of 0.95 or greater. "High density polyethylene"("HDPE") is an ethylene polymer having a density of about 0.94 g/cm ³ or greater.

Density, reported in g/ ^cm3 , was determined according to ASTM 1505-10 (the panels were molded according to ASTM D4703-10a, Procedure C, Panel Preparation, including conditioning the panels at 23°C for 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. The polydispersity index (PDI) is defined as Mw divided by Mn. All molecular weights (eg, Mw, Mn, Mz) are reported in g/mol unless otherwise indicated.

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

Unless otherwise indicated, molecular weight moments ( moment) and distribution (eg Mw, Mn, Mz, Mw/Mn) and comonomer content (eg _C2 , C3, _{C6 )} . Polymer separation was provided using three Agilent PLgel 10-μm Hybrid-B LS columns. Aldrich reagent grade 1,2,4-trichlorobenzene (TCB) with 300 ppm antioxidant butylated hydroxytoluene (BHT) was used as 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 1.0 mL/min and the nominal injection volume was 200 μL. The entire system including transfer lines, columns and detectors was housed in an oven maintained at 145°C. Polymer samples were weighed and sealed in standard vials with 80-μL flow marker (heptane) added to them. After loading the vial in the autosampler, the polymer was dissolved in the instrument with 8 mL of TCB solvent added. The polymer was dissolved by shaking continuously for about 1 hour for polyethylene samples or for about 2 hours for polypropylene samples at 160°C. The TCB densities used for the concentration calculations were 1.463 g/ml at room temperature and 1.284 g/ml at 145°C. Sample solution concentrations were 0.2-2.0 mg/mL, with lower concentrations for higher molecular weight samples. The concentration (c) at each point in the chromatogram was calculated from the baseline-subtracted IR5 broadband signal intensity (I) using the following equation: c=βI, where β is the mass constant. Mass recovery can be calculated from the ratio of the integrated area of the concentration chromatogram within the elution volume to the injected mass, which is equal to the predetermined concentration times the volume of the injection loop. Conventional molecular weight (IR molecular weight) was determined by combining a general calibration relationship with a column calibration performed with a series of monodisperse polystyrene (PS) standards ranging from 700 to 10,000,000 gm/mole. Calculate the molecular weight at each elution volume using (1):

Where variables with the subscript "PS" represent polystyrene, those without the subscript represent test samples. In this method, α _PS = 0.67 and K _PS = 0.000175, while α and K for other materials are disclosed and calculated as disclosed in the literature (Sun, T. et al. (2001) Macromolecules, vol. 34, p. 6812). , except for the purposes of this invention and the appended claims, α=0.705 and K=0.0002288 for linear propylene polymers, α=0.695 and K=0.000181 for linear butene polymers, and ethylene-butene copolymers α is 0.695 and K is 0.000579*(1-0.0087*w2b+0.000018*(w2b)^2) (where w2b is the bulk weight percent of butene comonomer), for ethylene-hexene copolymer α is 0.695 and K is 0.000579*(1-0.0075*w2b) (where w2b is the bulk weight percent of hexene comonomer), and for ethylene-octene copolymer alpha is 0.695 and K is 0.000579*(1-0.0077*w2b) (wherein w2b is the bulk weight percent of octene comonomer), and for all other linear ethylene polymers a = 0.695 and K = 0.000579. Unless otherwise indicated, concentrations are expressed in g/ ^cm3 , molecular weights are expressed in g/mole, and intrinsic viscosity (hence K in the Mark-Houwink equation) is expressed in dL/g.

Comonomer composition was determined by the ratio of IR5 detector intensities corresponding to _CH2 and _CH3 channels calibrated using a series of polyethylene and propylene homo/copolymer standards of predetermined nominal values by NMR or FTIR. In particular, this provides methyl groups/1,000 total carbons ( _CH3 /1000TC) as a function of molecular weight. Short chain branches (SCB) per 1,000TC can then be calculated as a function of molecular weight by applying chain end correction to the _CH3 /1000TC function, assuming each chain is linear and terminated by a methyl group at each end Content (SCB/1000TC). The wt % comonomer can then be obtained from the following expression, where f is 0.3, _0.4 , 0.6, _0.8 , etc. for C3, _C4 , _C6 , C8, etc. comonomers, respectively:

w2=f*SCB/1000TC Equation 2

The bulk compositions of polymers from GPC-IR and GPC-4D analyses were obtained by considering the entire signal of the _CH3 and _CH2 channels between the integration limits of the concentration chromatograms. First, the following ratios are obtained.

The same calibration for the _CH3 and _CH2 signal ratios (as previously mentioned in Obtaining _CH3 /1000TC as a function of molecular weight) was then applied to obtain bulk _CH3 /1000TC. Bulk methyl chain ends/1,000 TC (bulk CH ₃ ends/1000 TC) were obtained by weighted average chain end correction over the molecular weight range.

but

w2b=f* body CH ₃ /1000TC Equation 4

Body SCB/1000TC = Body _CH3 /1000TC - Body _CH3 end/1000TC Equation 5 and body SCB/1000TC are transformed into 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 the Zimm model for static light scattering (Light Scattering from Polymer Solutions, Huglin, M.B. ed., Academic Press, 1972):

Here, ΔR(θ) is the excess Rayleigh scattering intensity measured at scattering angle θ, c is the polymer concentration determined from IR analysis, A is the _second virial coefficient, and P(θ) is the monodisperse random the shape factor of the coil, and K _o is the optical constant of the system:

where NA is Avogadro's constant, and (dn/dc) is the refractive index increment of the system, n ₌ 1.500 for TCB at 145°C and λ=665 nm. For the analysis of ethylene homopolymers, ethylene-hexene copolymers and ethylene-octene copolymers, dn/dc = 0.1048 ml/ _mg and A2 = 0.0015; for the analysis of ethylene-butene copolymers, dn/dc dc=0.1048*(1-0.00126*w2)ml/ _mg and A2=0.0015, where w2 is the weight percent of butene comonomer, for all other ethylene polymers, dn/dc=0.1048ml/mg and A ₂ =0.0015.

其中α_ps为0.67并且K_PS为0.000175。样品的平均特性粘度<[η]>通过以下计算：Specific viscosity is determined using a high temperature viscometer, such as those made by Technologies, Inc. or Viscotek Corporation, which have four capillaries arranged in a Wheatstone bridge configuration, and two pressure sensors. One sensor measures the total pressure drop across the detector, and another sensor placed between the two sides of the bridge measures the differential pressure. The specific viscosity _ηs of the solution flowing through the viscometer is calculated from their outputs. The intrinsic viscosity [η] at each point in the chromatogram is calculated from the equation [η] = η _s /c, where c is the concentration and is determined from the IR5 broadband channel output. The viscosity MW at each point is calculated as

where _αps is 0.67 and KPS is _0.000175 . The average intrinsic viscosity <[η]> of the sample is calculated by:

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

The long chain branching index (g' _LCB , also referred to as g' _vis ) is defined as

where <M _IR > is the viscosity average molecular weight corrected using polystyrene standards, and K and α are used for reference linear polymers as described in the literature (Sun, T. et al. (2001) Macromolecules, Vol. 34, No. 6812 page), except for the purposes of this invention and the appended claims, α = 0.705 and K = 0.0002288 for linear propylene polymers and α = 0.695 for linear butene polymers and K = 0.000181, for an ethylene-butene copolymer, α is 0.695 and K is 0.000579*(1-0.0087*w2b+0.000018*(w2b)^2) (where w2b is the bulk weight of the butene comonomer percent), for ethylene-hexene copolymers, α is 0.695 and K is 0.000579*(1-0.0075*w2b) (where w2b is the bulk weight percent of hexene comonomer), and for ethylene-octene copolymers α is 0.695 and K is 0.000579*(1-0.0077*w2b) (where w2b is the bulk weight percent of octene comonomer), and for all other linear ethylene polymers α = 0.695 and K =0.0005.

g'Mz was determined by selecting the g' value at the _Mz value on the GPC-4D trace generated by the GPC method described above. The Mz value is obtained from the LS detector. For example, if the Mz-LS is 300,000 g/mol, use the value at 300,000 g/mol on the g' trace on the GPC-4D plot. g'Mw was determined by selecting the g' value at the _Mw value on the GPC-4D trace. The Mw value is obtained from the LS detector. For example, if the Mw-LS is 100,000 g/mol, use the value at 100,000 g/mol on the g' trace on the GPC-4D plot. g'Mn was determined by selecting the g' value at the _Mn value on the GPC-4D trace. The Mz value is obtained from the LS detector. For example, if Mn-LS is 50,000 g/mol, use the value at 50,000 g/mol on the g' trace on the GPC-4D plot.

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

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

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

where η _0.01 and η ₅₀ are the complex viscosities measured at 190°C with frequencies of 0.01 rad/s and 50 rad/s, respectively. DST parameters help to better differentiate and emphasize the branching characteristics of the samples.

相对0.1s^-1时的相应值之比：The extensional evolution of the instantaneous extensional viscosity was studied by an MCR501 rheometer with controlled operating speed available from Anton Paar. The linear viscoelastic envelope (LVE) was obtained by starting the steady state shear experiments. Strain hardening is defined as the rapid and sudden level off of extensional viscosity from linear viscoelastic behavior. Therefore, this nonlinear behavior is quantified by the strain hardening ratio (SHR), which is defined as the maximum instantaneous extensional viscosity at ^1s

Ratio of corresponding values relative to 0.1s ^-1 :

A value of 0.1s ^-1 is preferred over LVE because of the choice to employ only transient stretch rather than initiate steady-state shear data in the processing. When the SHR is greater than 1, the material exhibits strain hardening.

Differential Scanning Calorimetry (DSC) measurements were performed using a TA Instruments' Discovery 2500 unless otherwise indicated. The melting point or melting temperature (Tm), crystallization temperature (Tc), and heat of fusion or heat flow (ΔH _f or H _f ) were determined using the following DSC procedures. Samples weighing approximately 2 mg to 5 mg were enclosed in aluminum air tight pans. Heat flow was normalized by sample mass. The DSC was run from 0°C to 200°C at a rate of 10°C/min. After 45 seconds of equilibration, the sample was cooled down to 0°C at 10°C/min. The first and second thermal cycles were recorded. Unless otherwise specified, DSC measurements are based on 2nd crystallization and melting ramps. Melting temperature ( _Tm ) and crystallization temperature ( _Tc ) were calculated by integrating the melting and crystallization peaks (area under the curve). The endothermic melting transition was analyzed for transition onset and peak temperature, and an endothermic melting transition was considered to exhibit a broad melting peak if it was at least 7°C between the transition onset and peak temperature. For samples showing multiple peaks, the defined melting temperature was derived from the peak melting temperature of the DSC melting trace (ie, related to the thermal response of the maximum endotherm in that temperature range).

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

Melt Flow Index (MFI) or _I2 was measured on a Goettfert MI-4 Melt Indexer according to ASTM 1238-13. Test conditions were set at 190°C and 2.16kg load. Samples ranging from 5 g to 6 g were loaded into the barrel of the instrument at 190°C and compressed manually. Thereafter, the material is automatically compacted into the barrel by lowering all available weight onto the piston to remove all air bubbles. Data acquisition was started after a 6 minute pre-melt time. Again, the samples were extruded through a die of 8 mm length and 2.095 mm diameter.

As used herein, the terms "machine direction" and "MD" refer to the direction of stretch 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 "extrude" and its grammatical variants is meant to include forming a polymer and/or polymer blend into a melt, such as by heating and/or shearing, and then forcing the melt to, for example, The process by which the form or shape of the film comes out of the die. Most any type of equipment will be suitable for performing the extrusion, such as a single or twin screw extruder, or other melt blending apparatus known in the art and equipped with suitable dies.

The film thickness of the film is determined by ASTM D6988-13.

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

The calculation procedure is 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 stretch = maximum force/cross-sectional area.

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

Elongation was calculated as a function of the increase in length divided by the original length times 100. Elongation = increase in length/original length x 100%.

The yield point is the first point where strain (elongation) increases without stress (force). Yield is determined by the 2% bias method.

Tensile at 100% elongation was calculated as a function of force at 100% elongation divided by the cross-sectional area of the specimen. Stretch at 100% elongation = force/cross-sectional area at 100% elongation.

The stretch at 200% elongation was calculated as a function of the force at 200% elongation divided by the cross-sectional area of the specimen. Stretch at 200% elongation = 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 times 100, and is reported in PSI units. 1% Secant Modulus = Load at 1% Elongation/(Average Thickness (Inches) x Width) x 100.

Transparency is determined by ASTM D1746-15.

Haze is determined by ASTM D1003-13.

Gloss is determined by ASTM D2457-13.

Dart impact was determined by Phenolic Resin Method A in accordance with ASTM D1709-16ae1.

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 samples that are ~1 mil thick are placed in an approximately 4 inch wide ring clamp. A stainless steel custom plunger/probe, with a 3/4" tip and two 0.25 mil slides, was pressed through the sample at a constant speed of 10 in/min. After failure at five different locations selected from a standard membrane tape Obtain the results and calculate the average.

As used herein, the measurement per mil is calculated by dividing the measurement by the thickness value of the film. For example, a 2 mil film with 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) directions) as a 100 cm round film along MD under a heat gun (Model HG-501A) set to an average temperature of 750°F (399°C) and TD length percent reduction measurements. The heat gun was centered two inches above the samples and heat was applied until each sample stopped shrinking.

Water Vapor Transmission Rate (WVTR) was performed on MOCON Permatran W-700 and W3/61 obtained from MOCON, Inc. at 100°F (37.8°C) and 100% relative humidity using ASTM F1249 with no Load the sample with a specific orientation.

Polyethylene Synthesis

For the purposes of the present invention and its claims, the new numbering scheme of the Periodic Table of the Elements is used as described in Chemical and Engineering News, Vol. 63(5), p. 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,""hydrocarbylgroup," or "hydrocarbyl group" are used interchangeably and are defined to mean groups consisting only of hydrogen and carbon atoms. Preferred hydrocarbyl groups are _C1 - _C100 groups, 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 cyclopropyl, 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, usually one or two substituted or unsubstituted cyclopentadienyl ligands bonded to the transition metal, usually a metallocene catalyst is an organometallic compound containing two π-bonded cyclopentadienyl moieties (or substituted cyclopentadienyl moieties).

Substituted or unsubstituted cyclopentadienyl ligands include substituted or unsubstituted cyclopentadienyl, indenyl, fluorenyl, tetrahydro-s-indarenyl, tetrahydro-as-indarenyl, Benzo[f]indenyl, benzo[e]indenyl, tetrahydrocyclopenta[b]naphthalene (tetrahydrocyclopenta[b]naphthalene), tetrahydrocyclopentadieno[a]naphthalene, etc.

Unless otherwise indicated (eg, definition of "substituted hydrocarbyl," etc.), the term "substituted" means that at least one hydrogen atom has been replaced by at least one non-hydrogen group, such as a hydrocarbyl group, a heteroatom, or a heteroatom-containing group , such as halogen (eg Br, Cl, F or I) or at least one functional group such as -NR* ₂ , -OR*, -SeR*, -TeR*, -PR* ₂ , -AsR* ₂ , -SbR* ₂ , -SR*, -BR* ₂ , -S iR* ₃ , -GeR* ₃ , -SnR* ₃ , -PbR* ₃ , -(CH ₂ ) _q -SiR* ₃ instead, where q is 1 to 10 and each Each R* is independently hydrogen, hydrocarbyl, or halohydrocarbyl, and two or more R* may be joined together to form a substituted or unsubstituted fully saturated, partially unsaturated/or aromatic cyclic or polycyclic , or in which at least one heteroatom has been inserted into 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 by at least one heteroatom (eg, a halogen such as Br, Cl, F, or I) or a heteroatom-containing group (eg, Functional groups 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* ₃ , etc., wherein q is 1 to 10 and each R* is independently a hydrogen, hydrocarbyl or halohydrocarbyl group, and Two or more R* may be combined together to form a substituted or unsubstituted fully saturated, partially unsaturated/or aromatic cyclic or polycyclic ring structure) substituted, or wherein at least one heteroatom is inserted into the hydrocarbyl ring .

For the purposes of this disclosure, with respect to metallocene compounds, the term "substituted" means that a hydrogen atom has been replaced by a hydrocarbyl group, a heteroatom, or a heteroatom-containing group, such as a halogen (eg, Br, Cl, F or I) or at least one 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* ₃ instead, where q is 1 to 10 and each R* is independently hydrogen, hydrocarbyl, or halo hydrocarbyl, and two or more R* may be joined together to form a substituted or unsubstituted fully saturated, partially unsaturated/or aromatic cyclic or polycyclic ring structure, or in which at least one heteroatom has been inserted within the hydrocarbon ring.

The inventive ethylene-based copolymers useful herein are preferably made in a process comprising: subjecting ethylene and one or more C3 _{- C20} olefins in at least one gas phase reactor in the presence of a metallocene catalyst system Contact at a temperature in the range of 60°C-90°C and a reactor pressure of 70kPa-7,000kPa.

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

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

in:

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 ^a and R ^b are independently hydrogen, halogen or C ₁ -C ₂₀ substituted or unsubstituted hydrocarbyl, and R ^a and R ^b may form cyclic, partially saturated/or saturated cyclic groups including substituted or unsubstituted aromatics or cyclic structures of fused ring systems;

Each X ¹ and X ² is independently selected from C ₁ -C ₂₀ substituted or unsubstituted hydrocarbyl groups, hydrogen groups, amine groups, amines, alkoxy groups, thio groups, phosphorus groups, halo groups, dienes, phosphines and ethers, and X ¹ and X ² can form cyclic structures including aromatic, partially saturated/or saturated cyclic or fused ring systems;

Each of R ¹ , R ² , R ³ , R ⁴ , and R ⁵ is independently hydrogen, halo, alkoxy, or a C ₁ to C ₂₀ or C ₄₀ substituted or unsubstituted hydrocarbyl group, and any adjacent The R ² , R ³ , R ⁴ and/or R ⁵ groups may form fused or multicentric fused ring systems, wherein the rings may be substituted or unsubstituted and may be aromatic, partially unsaturated/or unsaturated saturated; and

Each of R ⁶ , R ⁷ , R ⁸ and R ⁹ is independently hydrogen or a C ₁ to C ₂₀ or C ₄₀ substituted or unsubstituted hydrocarbyl group, most preferably methyl, ethyl or propyl; and

A further condition is that at least two of R ⁶ , R ⁷ , R ⁸ and R ⁹ are C ₁ -C ₄₀ substituted or unsubstituted hydrocarbyl groups; wherein "hydrocarbyl" (or "unsubstituted hydrocarbyl") means carbon- Hydrogen groups such as methyl, phenyl, isopropyl, naphthyl, etc. (aliphatic, cyclic, and aromatic compounds composed of carbon and hydrogen), and "substituted hydrocarbyl" means having at least one Hydrocarbyl groups of bonded heteroatoms such as carboxyl, methoxy, phenoxy, BrCH ₃ —, NH ₂ CH ₃ — and the like.

Preferred metallocene compounds can be represented by the formula:

wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ^a , R ^b , X ¹ , X ² , T and M are as defined above; and R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently H or a C ¹ -C ⁴⁰ substituted or unsubstituted hydrocarbyl group.

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

wherein R ¹ , R ² , R ³ , R ⁴ , R 5 , ^Ra , R ^b , X ¹ , X ² , T, D and M are as defined above.

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

wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , ^Ra , R ^b , X ¹ , X ² , T and M are as defined above. In useful embodiments, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are hydrogen, and ^Ra , R ^b , X ¹ , X ² , T and M are as defined above.

Examples of preferred metallocene compounds include: dimethylsilylene(3-phenyl-1-indenyl)(2,3,4,5-tetramethyl-1-cyclopentadienyl)dichloro Zirconium; Dimethylsilylene (3-phenyl-1-indenyl) (2,3,4,5-tetramethyl-1-cyclopentadienyl)methylzirconium; bis(n-propyl) cyclopentadienyl) dimethyl Hf bis (n-propyl cyclopentadienyl) 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 can be carried out using any suitable method such as solution, slurry, high pressure and gas phase. A particularly desirable process for producing 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 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.

Metallocene catalysts are used with activators in polymerization processes to produce the polyethylenes of the present invention. As used herein, the term "activator" is any compound that can activate any of the catalyst compounds described above by converting the neutral catalyst compound into a catalytically active metallocene compound cation. Preferably, the catalyst system includes an activator. Activators useful herein include alumoxane or "non-coordinating anion" activators such as boron-based compounds (eg, tris(perfluorophenyl)borane or tetrakis(pentafluorophenyl)ammonium borate).

Catalyst systems useful herein may include at least one non-coordinating anion (NCA) activator such as an NCA activator represented by the formula:

Z _d ⁺ (A ^d- )

Where: 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 ^d- is a boron-containing non-coordinating anion with charge d-; d is 1, 2, or 3.

The cationic component Z _d ⁺ may include Bronsted acids such as protonated or protonated Lewis bases or reducible Lewis acids capable of protonation or abstraction of structures from transition metal catalyst precursors containing bulky ligand metallocenes moieties such as alkyl or aryl, resulting in cationic transition metal species.

、碳

、二茂铁

和混合物，优选碳

和二茂铁

。最优选地，Z_d ⁺是三苯基碳

。优选的可还原的路易斯酸可为任何三芳基碳

(其中芳基可为取代的或未取代的，例如由式：(Ar₃C⁺)表示的那些，其中Ar是芳基或被杂原子、C₁-C₄₀烃基或取代的C₁-C₄₀烃基取代的芳基)，优选以上式(14)中的可还原的路易斯酸，如“Z”包括由式(Ph₃C)表示的那些，其中Ph是取代的或未取代的苯基，优选取代有C₁-C₄₀烃基或取代的C₁-C₄₀烃基、优选C₁-C₂₀烷基或芳族化合物或取代的C₁-C₂₀烷基或芳族化合物，优选Z是三苯基碳

。The activating cation Z _d ⁺ can also be a moiety such as silver,

,carbon

, ferrocene

and mixtures, preferably carbon

and ferrocene

. Most preferably, Z _d ⁺ is a triphenyl carbon

. Preferred reducible Lewis acids can be any triaryl carbon

(wherein aryl may be substituted or unsubstituted, such as those represented by the formula: ( _Ar3C ⁺ ), where Ar is aryl or a heteroatom, _C1 - _C40 hydrocarbyl, or _C1 -C substituted ₄₀ hydrocarbyl-substituted aryl), preferably a reducible Lewis acid of formula (14) above, such as "Z" including those represented by formula ( _Ph3C ), wherein Ph is a substituted or unsubstituted phenyl, Preferably substituted with C ₁ -C ₄₀ hydrocarbyl or substituted C ₁ -C ₄₀ hydrocarbyl, preferably C ₁ -C ₂₀ alkyl or aromatic or substituted C ₁ -C ₂₀ alkyl or aromatic, preferably Z is tris phenyl carbon

.

、

、甲硅烷

和它们的混合物，优选甲胺、苯铵、二甲胺、二乙胺、N-甲基苯铵、二苯胺、三甲胺、三乙胺、N,N-二甲基苯胺、甲基二苯胺、吡啶、对-溴-N,N-二甲基苯胺、对-硝基-N,N-二甲基苯胺的铵，来自三乙基膦、三苯基膦和二苯基膦的

，来自醚例如二甲醚、二乙醚、四氢呋喃和二氧六环的氧

，来自硫醚例如二乙硫醚、四氢噻吩的锍，和它们的混合物。When Z _d ⁺ is an activating cation (L–H) _d ⁺ , it is preferably a Bronsted acid capable of donating protons to transition metal catalytic precursors, resulting in transition metal cations including ammonium, oxygen

,

, Monosilane

and their mixtures, preferably methylamine, anilidine, dimethylamine, diethylamine, N-methylanilinium, diphenylamine, trimethylamine, triethylamine, N,N-dimethylaniline, methyldiphenylamine , pyridine, ammonium p-bromo-N,N-dimethylaniline, p-nitro-N,N-dimethylaniline, from triethylphosphine, triphenylphosphine and diphenylphosphine

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

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

Anionic components A ^d- include those having the 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); nk=d; M is an element selected from group 13 of the periodic table, preferably boron or aluminium, and Q is independently hydrogen, bridged or unbridged dialkylamino, halo, alkane Oxy, aryloxy, hydrocarbyl, substituted hydrocarbyl, halohydrocarbyl, substituted halohydrocarbyl, and halogen-substituted hydrocarbyl groups, where Q has up to 20 carbon atoms, provided that Q occurs in no more than 1 occurrence is halogen. 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. Examples of suitable Ad- also include diboron compounds as disclosed in US Pat. No. ^5,447,895 , which is incorporated herein by reference in its entirety.

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

、四(全氟联苯基)硼酸三苯基碳

、四(3,5-双(三氟甲基)苯基)硼酸三苯基碳

或四(全氟苯基)硼酸三苯基碳

。Most preferably, the activator Z _d ⁺ (A ^d- ) is one or more of the following: N,N-dimethylanilinium tetrakis(perfluorophenyl)borate, tetrakis(perfluoronaphthyl)boronic acid N,N-dimethylanilinium, N,N-dimethylanilinium tetrakis(perfluorobiphenyl)borate, N,N-tetrakis(3,5-bis(trifluoromethyl)phenyl)boronic acid Dimethylanilinium, triphenylcarbon tetrakis(perfluoronaphthyl)borate

, triphenylcarbon tetrakis(perfluorobiphenyl)borate

, tetrakis(3,5-bis(trifluoromethyl)phenyl)boronic acid triphenylcarbon

or triphenylcarbon tetrakis(perfluorophenyl)borate

.

Alternatively, preferred activators may include alumoxane compounds (or "aluminoxanes") and modified alumoxane compounds. ^Aluminoxanes are generally oligomeric compounds containing -Al(R1)-O- subunits, where R1 is ^an alkyl group. Examples of alumoxanes include methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane, isobutylaluminoxane, and mixtures thereof. Alkyl aluminoxanes and modified alkyl aluminoxanes are useful as catalyst activators, especially when the abstractable ligand is an alkyl, halo, alkoxy or amino group. Mixtures of different alumoxanes and modified alumoxanes can also be used. Visually clear methylaluminoxane may preferably be used. The cloudy or gelled alumoxane can be filtered to yield a clear solution or the clear alumoxane can be decanted from the cloudy solution. Another useful alumoxane is Modified Methylalumoxane (MMAO) cocatalyst Type 3A (commercially available from Akzo Chemicals, Inc. under the tradename Modified Methylalumoxane Type 3A, disclosed in US 5,041,584). Preferably in the present invention, the activator is an alkylaluminoxane, preferably methylaluminoxane or isobutylaluminoxane, most preferably methylaluminoxane.

Preferably, the activator is supported on the support material prior to contact with the metallocene compound. Additionally, the activator can be combined with the metallocene compound prior to placement on the support material. Preferably, the activator can be combined with the metallocene compound in the absence of a support material.

As a supplement to the activator compound, co-activators can be used. Alkyl aluminum or organometallic compounds that can be used as cocatalysts (or scavengers) include, for example, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, Dibutyl zinc, diethyl zinc, etc.

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 materials, or mixtures thereof.

Preferably, the support material is an inorganic oxide in 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 silica or alumina are magnesia, titania, zirconia, and the like. However, other suitable support materials may be employed, such as finely divided functionalized polyolefins such as finely divided polyethylene. Particularly useful supports include magnesia, titania, zirconia, montmorillonite, phyllosilicates, zeolites, talc, clays, and the like. Additionally, combinations of these support materials can be used, such as silica-chromium, silica-alumina, silica-titania, and the like. Preferred support materials include Al ₂ O ₃ , ZrO ₂ , SiO ₂ and combinations thereof, more preferably SiO ₂ , Al ₂ O ₃ or SiO ₂ /Al ₂ O ₃ .

The supported catalyst system can be suspended in a paraffinic reagent such as mineral oil. Processes and catalyst compounds useful in making polyethylene useful herein are further described in US 9,266,977, US 9,068,033, US 6,225,426 and US 2018/0237554, all of which are incorporated herein by reference.

polyethylene

The polyethylene may be an ethylene homopolymer or an ethylene copolymer, such as an ethylene-α-olefin (preferably C3 _{- C20} α-olefin) copolymer (eg ethylene-butene copolymer, ethylene-hexene copolymer and/or ethylene-octene copolymer) having a Mw/Mn of 5 or more (preferably 5 to 10). Unless otherwise specified, the term "polyethylene" encompasses both ethylene homopolymers and ethylene copolymers.

The comonomer content of the polyethylene (cumulatively if more than one comonomer is used) can range from 0 mol% (ie, 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%), the balance being ethylene. Thus, the ethylene content of the polyethylene may 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 (cumulatively if more than one comonomer is used) can range from 0 wt% (ie, homopolymer) to 25 wt% (or 0.5 wt% to 20 wt%, or 1 wt% to 15 wt%, or 3 wt% to 10 wt%, or 6 to 10 wt%) and the ethylene content of the polyethylene may be 75 wt% or more ethylene (or 75 wt% to 100 wt%, or 80 wt% to 99.5 wt%, or 85 wt% to 99 wt%, or 90 wt% to 97 wt%, or 4 to 90 wt%). In a preferred embodiment, the comonomer is present at 6 to ₁₀ % by weight and is preferably a C3 _- C12 alpha-olefin (preferably one or more of propylene, butene, hexene and octene).

_The comonomer may be one or more C3 _{- C20} olefin comonomers (preferably a C3 _- C12 alpha-olefin; more preferably propylene, butene, hexene, octene, decene and/or dodecene carbene; 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 films of the present disclosure may have:

(A) a melt index I ₂ of 1.0 g/10min or more (or 1.5 to 5 g/10min, or 1.8 to 4 g/10min, or 1.9 to 3 g/10min);

(B) Density of 0.925 g/cm ³ to 0.945 g/cm ³ (0.927 g/cm ³ to 0.942 g/cm ³ , or 0.93 g/cm ³ to 0.941 g/cm ³ , or 0.931 g/cm ³ to 0.94 g/cm ³ );

(C) g' _LCB is less than 0.8 (or 0.78-0.5, or 0.75-0.5);

(D) Mz of 1,000,000 g/mol or greater, or 1,200,000 g/mol or greater, or 1,300,000 g/mol or greater, or 1,200,000 to 3,000,000 g/mol;

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

(F) Mw of 100,000 g/mol or greater, or 120,000 g/mol or greater, or 130,000 g/mol or greater, or 140,000 g/mol or greater, such as from 100,000 to 200,000 g/mol, or 130,000- 155,000g/mol;

(G) the ratio of g' _LCB to g' _Zave 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 60,000 psi or greater, a dart impact of 250 g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

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

(A) a melt index I ₂ of 1.0 g/10min or more (or 1.5 to 5 g/10min, or 1.8 to 4 g/10min, or 1.9 to 3 g/10min);

(B) Density of 0.925 g/cm ³ to 0.945 g/cm ³ (0.927 g/cm ³ to 0.942 g/cm ³ , or 0.93 g/cm ³ to 0.941 g/cm ³ , or 0.931 g/cm ³ to 0.94 g/cm ³ );

(C) g' _LCB is less than 0.8 (or 0.78-0.5, or 0.75-0.5);

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

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

(F) Mw of 100,000 g/mol or greater, or 120,000 g/mol or greater, or 130,000 g/mol or greater, or 140,000 g/mol or greater, such as from 100,000 to 200,000 g/mol, or 130,000- 155,000g/mol;

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, or 1.5-10, or 2.0-5;

(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; 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°C or more (or 122°C to 127°C, or 123°C to 125°C),

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

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

(N) is at least 7°C (or at least 10°C, or at least 15°C) between the transition onset and the melting peak, as shown in the DSC trace.

Additionally, polyethylenes (including any of the foregoing) used in the films of the present disclosure may have an Mz-LS/Mn-Ls of 15 or greater, or 20 or greater.

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

In preferred embodiments, the polyethylenes described herein have at least 7°C (or at least 10°C, or at least 15°C) between the transition onset and the melting peak, as shown in the DSC trace.

In preferred embodiments, the polyethylenes described herein have at least 10°C (or at least 15°C, or at least 20°C) between the melting peak and the crystallization peak.

blend

In another embodiment, the polyethylene composition prepared herein is combined with one or more additional polymers in a blend prior to formation into a film. As used herein, "blend" can refer to dry or extruder blends of two or more different polymers, and in-reactor blends, including those used in a single reactor zone Blends produced by multiple catalyst systems or mixed catalyst systems, and blends produced by using one or more catalysts in one or more reactors under the same or different conditions (for example, by each blends produced by series reactors (same or different) operating under and/or using different catalysts.

Useful additional polymers include other polyethylenes, isotactic polypropylene, highly isotactic polypropylene, syndiotactic polypropylene, random copolymers of propylene and ethylene and/or butene and/or hexene polybutene, ethylene vinyl acetate, LDPE, LLDPE, HDPE, ethylene vinyl acetate, ethylene methyl acrylate, copolymers of acrylic acid, polymethyl methacrylate or any other polymer that can be polymerized by high pressure free radical methods polyvinyl chloride, polybutene-1, isotactic polybutene, ABS resin, ethylene-propylene rubber (EPR), vulcanized EPR, EPDM, block copolymer, styrenic block copolymer, poly Amides, polycarbonates, PET resins, cross-linked polyethylene, copolymers of ethylene and vinyl alcohol (EVOH), polymers of aromatic monomers such as polystyrene, poly-1 ester, polyacetal, polyvinylidene fluoride Ethylene, polyethylene glycol and/or polyisobutylene.

Membrane and method

The polyethylene prepared by the methods described herein is preferably formed into a film, especially an oriented film, such as a biaxially oriented film.

The present disclosure relates to oriented polyethylene films comprising LLDPE with properties that improve processability while providing a good balance of stiffness in machine and transverse directions while providing high toughness (or impact resistance).

For example, the present invention relates to biaxially oriented films comprising polyethylene having the following:

(A) a melt index I ₂ of 1.0 g/10min or more (or 1.5 to 5 g/10min, or 1.8 to 4 g/10min, or 1.9 to 3 g/10min);

(B) Density of 0.925 g/cm ³ to 0.945 g/cm ³ (0.927 g/cm ³ to 0.942 g/cm ³ , or 0.93 g/cm ³ to 0.941 g/cm ³ , or 0.931 g/cm ³ to 0.94 g/cm ³ );

(C) g' _LCB is less than 0.8 (or 0.78-0.5, or 0.75-0.5);

(D) Mz of 1,000,000 g/mol or greater, or 1,200,000 g/mol or greater, or 1,300,000 g/mol or greater, or 1,200,000 to 3,000,000 g/mol;

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

(F) Mw of 100,000 g/mol or greater, or 120,000 g/mol or greater, or 130,000 g/mol or greater, or 140,000 g/mol or greater, such as from 100,000 to 200,000 g/mol, or 130,000- 155,000g/mol;

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, or 1.5-10, or 2.0-5;

(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;

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

(J) optionally, at least 7°C (or at least 10°C, or at least 15°C) between the transition onset and the melting peak, as shown in the DSC trace;

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

wherein the ratio of 1% secant MD/1% secant TD is 0.65 or greater, or 0.7 greater, or 0.75 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 more, or 0.35 or more, or 0.4 or more, or 0.30 to 1.1, or 0.35 to 1.

The films described herein may also have a gloss of 60% or less, eg, 20 to 55%.

The films described herein can also have a Dart Impact A of 250 g/mil to 1,350 g/mil (or 275 g/mil to 1,300 g/mil, or 300 g/mil 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 polyethylenes described herein. Preferably, the films of the present disclosure comprise polyethylene in an amount of at least 90 wt% (or 90 wt% to 100 wt%, or 90 wt% to 99.9 wt%, or 95 wt% to 99 wt%). Advantageously, the polyethylene described herein does not need to be mixed with another polymer 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 thermal or light stabilizers), antistatic agents, crosslinking agents or adjuvants, crosslinking accelerators, mold release agents, adhesion promoters, plasticizers, Anti-caking agents (eg oleamide, stearamide, erucamide or other derivatives with the same activity) and fillers.

1076(高分子量酚类抗氧化剂，可从BASF得到)、IRGAFOS

168(三(2,4-二叔丁基苯基)亚磷酸酯，可从BASF得到)和三(壬基苯基)亚磷酸酯。加工助剂的非限制性实例是DYNAMAR

FX-5920(自由流动的基于氟聚合物的加工添加剂，可从3M得到)。Non-limiting examples of antioxidants include, but are not limited to, IRGANOX

1076 (high molecular weight phenolic antioxidant, available 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 amount can range cumulatively 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 include: producing a polymer melt comprising the polyethylene described herein; extruding the film from the polymer melt; stretching in the machine direction at a temperature below the melting point of the polyethylene film to produce a machine direction oriented (MDO) polyethylene film; and stretching the MDO polyethylene film in the cross direction to produce a biaxially oriented polyethylene film.

Stretching in the machine direction can be achieved by passing the film through a series of rolls, wherein the temperature and speed of the individual rolls are 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, preheat rolls, various stretching stages (with or without annealing rolls between stages), one or more conditioning and annealing rolls, and one or more cooling rolls. The stretching of the film in the MDO stage is accomplished by inducing a speed difference between two or more adjacent rolls.

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

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

As the film passes through the stretching zone of the TDO stage oven, transverse stretching can be achieved by pulling the film from the edges in a tenter, which is a series of moving clamps. A TDO stage oven typically has three zones: (1) a preheat zone to soften the film, (2) a stretch zone to stretch the film in the transverse direction and (3) an anneal zone to cool and relax the stretched film.

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

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 longitudinal direction may be in the temperature range of at least 3°C, preferably at least 6°C, preferably at least 7°C, preferably at least 8°C, preferably at least 10°C, preferably at least 12°C, or 3-20°C, or 5-15°C Stretched polyethylene.

Likewise, at least 3°C, at least 5°C, preferably at least 6°C, preferably at least 7°C, preferably at least 8°C, preferably at least 10°C, preferably at least 12°C, or 3-20°C, or 3-15°C, or The polyethylene is stretched in the transverse direction within a temperature range of 3-10°C, or 3-6°C.

Preferably, at least 3°C, at least 5°C, preferably at least 6°C, preferably at least 7°C, preferably at least 8°C, preferably at least 10°C, preferably at least 12°C, or 3-20°C, or 3-15°C, Either 3-10°C, or 3-6°C, the film is stretched in the transverse direction without tearing the web and creating non-uniform film thickness.

Preferably, the longitudinal direction may be in a temperature range of at least 3°C, preferably at least 6°C, preferably at least 7°C, preferably at least 8°C, preferably at least 10°C, preferably at least 12°C, or 3-20°C, or 5-15°C The film is stretched without web instability and large film thickness variations. The wider stretching temperature range in both the MD and TD sections allows for greater flexibility in achievable line speeds and stretch ratios when operating the machine.

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

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

The biaxially oriented polyethylene films described herein can have (I) a 1% secant in the transverse direction of 60,000 psi or more (or 70,000 psi or more, or 75,000 psi to 150,000 psi, or 80,000 psi to 140,000 psi , or 90,000 psi to 130,000 psi), (II) 1% secant in the machine direction of 50,000 psi or more (or 60,000 psi or more, or 75,000 psi to 150,000 psi, or 80,000 psi to 140,000 psi, or 90,000 psi to 130,000 psi) 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 films described herein may have one or more of (I), (II) and (III) above and the following properties:

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

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

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

(VII) Dart drop impact A is 250g to 1,350g (or 275g to 1,300g, or 300g to 1,250g).

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

The biaxially oriented polyethylene films 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 0.925 g/cm ³ to 0.945 g/cm ³ (0.927 g/cm ³ to 0.942 g/cm ³ , or 0.93 g/cm ³ to 0.941 g/cm ³ , or 0.931 g/cm ³ to 0.931 g/cm 3 ) 0.94g/cm ³ ),

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

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

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

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

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

Preferably, the biaxially oriented polyethylene films described herein have 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 films described herein may have a yield strength in the machine direction of 2,000 psi to 5,000 psi (or 2,200 psi to 4,000 psi) and a yield strength in the cross direction of 4,000 psi to 4,000 psi The ratio of 15,000 psi (or 5,000 psi to 11,000 psi) and 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.

In any of the embodiments herein, the biaxially oriented polyethylene films described herein can have a tensile strength of 6,000 psi to 15,000 psi (or 7,500 psi to 14,500 psi, or 8,000 psi to 11,000 psi) in the machine direction and 6,000 psi to 11,000 psi in the transverse direction Tensile strength on the Either 0.4 or greater, or 0.30 to 1.1, or 0.35 to 1.

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

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

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

In any of the embodiments herein, the biaxially oriented polyethylene films described herein may have an average density of 0.925 g/cm ³ to 0.945 g/cm ³ (0.927 g/cm ³ to 0.942 g/cm ³ , or 0.93 g/cm 3 ) cm ³ to 0.941 g/cm ³ , or 0.931 g/cm ³ to 0.94 g/cm ³ ).

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

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

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

In any of the embodiments herein, the biaxially oriented polyethylene films described herein can have a clarity of 30% to 80% (or 45% to 75%).

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

end use

The biaxially oriented polyethylene films described herein can be used as monolayer films 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, etc., MDO polymer films, and other bilayers. Axial oriented polymer film.

Specific end-use films include, for example, blown film, cast film, stretch film, stretch/cast film, stretch cling film, stretch hand wrap film, machine stretch wrap film, shrink film, shrink wrap film, greenhouse Films, Laminates, and Laminated Films. Examples are prepared by any conventional technique known to those skilled in the art, such as techniques used to prepare blown, extruded and/or cast stretched and/or shrink films (including shrink-on-shrink applications) Sexual membrane.

The 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 bags, baked and frozen food packaging, diaper backsheets, housewrap, medical packaging (eg, medical films and intravenous (IV) bags), industrial liners, films, etc.

In one embodiment, the multilayer film or films of multiple layers may be formed by methods known in the art. The overall thickness of the multilayer film can 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. Those 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, resin or copolymer used, equipment capabilities, and other factors. The materials forming each layer can be coextruded through a coextrusion feedblock and die assembly to produce a film having two or more layers that are adhered together but differ in composition. Coextrusion can 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 consists 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 "A" or "B". When a film includes more than one A layer or more than one B layer, the A or B symbol is appended with one or more apostrophes (', ", '", etc.) to denote the same type of layers, which may be the same or may be differ in one or more properties, such as chemical composition, density, melt index, thickness, and the like. Finally, the symbols of adjacent layers are separated by a slash (/). Using this notation, a three-layer film with an inner layer disposed between two outer layers would be denoted A/B/A'. Similarly, a five-layer film of alternating layers would be denoted A/B/A'/B'/A". Unless otherwise indicated, the left-to-right or right-to-left order of the layers does not matter, nor does the order of the apostrophes For example, for the purposes described herein, A/B film is equivalent to B/A film, and A/A'/B/A" film is equivalent to A/B/A'/A" film. Analogously indicates individual film layers , where the values represent the thickness of the individual layers relative to a total film thickness of 100 (dimensionless) and are separated by slashes; eg A/B/A with 10 μm of A and A’ layers each and 30 μm of B layer 'The relative thickness of the film is expressed 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 invention provides multilayer films having any of the following exemplary structures: (a) two-layer 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 films such as A/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", B/A/B'/B" and B/B'/B"/B'"; (d) Five-layer film such as A/A'/A"/A'" /B, A/A'/A"/B/A'", A/A'/B/A"/A'", A/A'/A"/B/B', A/A'/B /A"/B', A/A'/B/B'/A", A/B/A'/B'/A", A/B/A'/A"/B, B/A/A '/A"/B', A/A'/B/B'/B", A/B/A'/B'/B", A/B/B'/B"/A', B/A /A'/B'/B", B/A/B'/A'/B", B/A/B'/B"/A', A/B/B'/B"/B'", B/A/B'/B"/B'", B/B'/A/B"/B'" and B/B'/B"/B'"/B""; and with six, seven, Eight, nine, twenty-four, forty-eight, sixty-four, one-hundred, or any other number of layers of similarly structured films. It should be appreciated that the films have even more layers.

In any of the above embodiments, one or more of the A layers may be replaced by substrate layers such as glass, plastic, paper, metal, etc., or the entire film may be coated or laminated to the substrate. Thus, although the discussion herein focuses on multilayer films, films can also be used as coatings for substrates such as paper, metal, glass, plastic, and other materials capable of receiving coatings.

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

Example implementation

The present invention also relates to:

1. Biaxially oriented polyethylene film comprising polyethylene having:

(A) a melt index I ₂ of 1.0 g/10 min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB is less than 0.8,

(D) Mz of 1,000,000 g/mol or more,

(E) Mw/Mn is 5 or more,

(F) Mw of 100,000 g/mol or more,

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, and

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

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

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

3. The film of paragraph 1 or 2, wherein the polyethylene described herein has at least 10°C between the transition onset 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°C between the melting peak and the crystallization peak.

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

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

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

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

(A) a melt index I ₂ of 1.9 to 3 g/10min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB of 0.78 to 0.5,

(D) Mz of 1,300,000 g/mol or greater, and

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

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

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

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

(VI) Peak force/mil from 10 lbs/mil to 40 lbs/mil, and

(VII) Dart impact A is 250 g/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) an average density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(X) 5% to 15% elongation at yield in the machine 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 from 5% to 35%,

(XIII) 30% to 80% transparency, and

(IX) An energy to break of 5 lbs*in to 25 lbs*in and/or an energy to break/mil of 5 lbs*in/mil to 19 lbs*in/mil.

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

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

13. Methods, including:

A polymer melt containing polyethylene with the following is produced:

(A) a melt index I ₂ of 1.0 g/10 min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB is less than 0.8,

(D) Mz of 1,000,000 g/mol or more,

(E) Mw/Mn is 5 or more,

(F) Mw of 100,000 g/mol or more,

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, and

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

Extrusion of films from polymer melts;

stretching the film in the machine direction to produce a machine direction oriented (MDO) polyethylene film; and

The MDO polyethylene film is stretched in the cross direction to produce a biaxially oriented polyethylene film, wherein the film has a 1% secant of 60,000 psi or greater in the cross direction, a dart impact of 250 g/mil or greater and a 1% positive The ratio of secant MD/1% secant TD is 0.65 or greater.

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

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

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

17. The method of any of paragraphs 13-16, wherein the film is stretchable in the cross direction at 8°C without web breakage or tearing and stretchable in the cross direction at 5°C without web breakage or tearing crack.

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

(I) a degree of shear thinning of 0.85 to 0.95,

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

(K) a melting temperature of 122°C or greater,

(L) a crystallization temperature of 110°C or more,

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

(N)Mw/Mn is 5 to 10.

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

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

21. The method of any of paragraphs 13-20, wherein the biaxially oriented film has a thickness of 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 of 2,000 psi to 5,000 psi in the machine direction and 5,000 psi to 11,000 psi in the transverse direction,

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

(VI) Peak force/mil from 10 lbs/mil to 40 lbs/mil, and

(VII) Dart impact A is 250 g/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) an average density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(X) 5% to 15% elongation at yield in the machine 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 5% to 35%

(XIII) 30% to 80% transparency, and

(IX) An energy to break of 5 lbs*in to 25 lbs*in and/or an energy to break/mil of 5 lbs*in/mil to 19 lbs*in/mil.

24. Polyethylene having:

(A) a melt index I ₂ of 1.0 g/10 min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB is less than 0.8,

(D) Mz of 1,000,000 g/mol or more,

(E) Mw/Mn is 5 or more,

(F) Mw of 100,000 g/mol or more,

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, and

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

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

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

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

(I) a degree of shear thinning of 0.85 to 0.95,

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

(K) a melting temperature of 122°C or greater,

(L) a crystallization temperature of 110°C or more,

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

(N)Mw/Mn is 5 to 10.

The present invention also relates to:

1A. Biaxially oriented polyethylene film comprising polyethylene having:

(A) a melt index I ₂ of 1.0 g/10 min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB is less than 0.8,

(D) Mz of 1,000,000 g/mol or more,

(E) Mw/Mn is 5 or more,

(F) Mw of 100,000 g/mol or more,

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, and

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

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

2A. 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.

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

4A. The film of paragraph 1A, wherein the polyethylene described herein has at least 10°C between the melting peak and the crystallization peak.

5A. The film of paragraph 1A, wherein the polyethylene is present at 90% to 100% by weight of the biaxially oriented film.

6A. The film of paragraph 1A, wherein the biaxially oriented film further comprises 0.01% to 1% by weight of an additive of the biaxially oriented film.

7A. The film of paragraph 1A, wherein the biaxially oriented film has a thickness of 0.1 to 3 mils or less.

8A. The film of paragraph 1A, wherein the polyethylene has:

(A) a melt index I ₂ of 1.9 to 3 g/10min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB of 0.78 to 0.5,

(D) Mz of 1,300,000 g/mol or greater, and

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

9A. The film of paragraph 1A, wherein the biaxially oriented film has one or more of the following properties:

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

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

(VI) Peak force/mil from 10 lbs/mil to 40 lbs/mil, and

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

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

(IX) an average density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(X) 5% to 15% elongation at yield in the machine 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 5% to 35%

(XIII) 30% to 80% transparency, and

(IX) An energy to break of 5 lbs*in to 25 lbs*in and/or an energy to break/mil of 5 lbs*in/mil to 19 lbs*in/mil.

11A. The film of paragraph 1A, wherein the biaxially oriented film has a thickness of 0.3 mil to 2 mil.

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

13A. A method comprising:

A polymer melt containing polyethylene with the following is produced:

(A) a melt index I ₂ of 1.0 g/10 min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB is less than 0.8,

(D) Mz of 1,000,000 g/mol or more,

(E) Mw/Mn is 5 or more,

(F) Mw of 100,000 g/mol or more,

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, and

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

Extrusion of films from polymer melts;

stretching the film in the machine direction to produce a machine direction oriented (MDO) polyethylene film; and

An MDO polyethylene film is stretched in the cross direction to produce a biaxially oriented polyethylene film, wherein the film has a 1% secant of 60,000 psi or greater in the cross direction, a dart impact of 250 g/mil or greater and a 1% positive The ratio of secant MD/1% secant TD is 0.65 or greater.

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

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

16A. The method of paragraph 13A, wherein the stretching is a stretch ratio of 1 to 10 in the machine direction, and wherein the stretching is a stretch ratio of 1 to 12 in the transverse direction.

17A. The method of paragraph 13A, wherein the film is stretchable in the cross direction at 8°C without web rupture or tearing and in the cross direction at 5°C without web rupture or tearing.

18A. The method of paragraph 13A, wherein the polyethylene has:

(I) a degree of shear thinning of 0.85 to 0.95,

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

(K) a melting temperature of 122°C or greater,

(L) a crystallization temperature of 110°C or more,

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

(N)Mw/Mn is 5 to 10.

19A. The method of paragraph 13A, wherein the polyethylene is present at 90% to 100% by weight of the polymer melt.

20A. The method of paragraph 13A, wherein the polymer melt further comprises 0.01% to 1% by weight of an additive of the polymer melt.

21A. The method of paragraph 13A, wherein the biaxially oriented film has a thickness of 0.1 to 3 mils.

22A. The method of paragraph 13A, wherein the biaxially oriented film has one or more of the following properties:

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

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

(VI) Peak force/mil from 10 lbs/mil to 40 lbs/mil, and

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

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

(IX) an average density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(X) 5% to 15% elongation at yield in the machine 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 5% to 35%

(XIII) 30% to 80% transparency, and

(IX) An energy to break of 5 lbs*in to 25 lbs*in and/or an energy to break/mil of 5 lbs*in/mil to 19 lbs*in/mil.

24A. Polyethylene, having:

(A) a melt index I ₂ of 1.0 g/10 min or more,

(B) a density of 0.925 g/cm ³ to 0.945 g/cm ³ ,

(C) g' _LCB is less than 0.8,

(D) Mz of 1,000,000 g/mol or more,

(E) Mw/Mn is 5 or more,

(F) Mw of 100,000 g/mol or more,

(G) the ratio of g' _LCB to g' _Zave is greater than 1.0, and

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

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

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

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

(I) a degree of shear thinning of 0.85 to 0.95,

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

(K) a melting temperature of 122°C or greater,

(L) a crystallization temperature of 110°C or more,

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

(N)Mw/Mn is 5 to 10.

To facilitate a better understanding of the 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 limiting the scope of the invention.

experiment

Catalyst A is Me ₂ Si[Me ₄ Cp][3-Ph-Ind]ZrCl ₂ , dimethylsilyl(tetramethyl-cyclopentadienyl)(3-phenylindenyl)zirconium dichloride and prepared as generally described in US 9,266,977 (see Metallocene 1).

Preparation of Me ₂ Si[Me ₄ Cp][3-Ph-Ind]ZrCl ₂ Supported Catalyst

Activation and loading of _Me2Si [Me4Cp][ _{3 -} Ph-Ind]ZrCl2 was prepared as follows. 687 g amount of methylaluminoxane (MAO) (30% by weight in toluene) was added together with 1504 g amount of toluene in a dry box in a 4 L stirred vessel. Metallocene was added in an amount of 15.7 g dissolved in 200 mL of toluene. The solution was then stirred at 60 rpm for 5 minutes. Another 165 g amount of toluene was added. The solution was stirred at 120 rpm for 30 minutes. Reduce the stirring speed to 8 rpm. ES-70 ^™ silica (PQ Corporation, Conshohocken, PA) that had been calcined at 875°C was added to the vessel. The slurry was stirred with another 154 grams of toluene for rinsing for 30 minutes, 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.

polymerization

The polymerization was carried out in a 22 foot high gas phase fluidized bed reactor with a 13 inch straight inner diameter and a wider conical extension above. Recycle and feed gases were fed into the reactor body through a perforated distributor plate, and the reactor was controlled at 290 psig and 64 mol% ethylene. The reactor temperature is controlled by manipulating the temperature of the recycle gas loop.

The catalyst was fed to the reactor as a dry powder with _N2 carrier gas. A 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 a weight concentration in the bed between 20 ppm and 40 ppm. Good reactor operability was observed for all conditions. Polymerization processing conditions can be found in Table A.

Table A

polymer product product A product B catalyst(-) catalyst A catalyst A Bed Temperature (°F) 185.0 185.0 Reactor pressure (psig) 289.1 290.0 Ethylene concentration (mol%) 63.8 63.9 H₂/C₂=gas ratio (ppm/mol%) 5.60 5.28 C₆/C₂ = flow rate ratio (lb/lb) 0.079 0.062 Composition of iC₅ (mol%) 3.7 3.9 Subsidence bulk density (g/cm³) 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: GPC4D Structural Parameters

Table 2: DSC Structure Parameters

Table 3: Structural and rheological parameters

property testing procedure

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

Differential Scanning Calorimetry (DSC)

DSC runs were performed using a TA Instruments' Discovery 2500. Peak melting point or melting temperature (Tm), peak crystallization temperature or crystallization temperature (Tc), and heat of fusion or heat flow (ΔHf or Hf) were determined using the following DSC procedures. Samples weighing approximately 2-5 mg were carefully sealed in aluminum air tight pans. Heat flow was normalized by sample mass. The DSC was run from 0°C to 200°C at a rate of 10°C/min, and after equilibration, the samples were cooled down to 0°C at 10°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°C to about 135°C (baseline).

Membrane production

Biaxially oriented polyethylene films were produced on Parkinson Technologies Inc's BIAX laboratory pilot line, which is a small scale variant of a commercial line. The BIAX laboratory pilot line has 5 main sections: extrusion, casting, MD, TD and winding.

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

In the following experiments, the BIAX laboratory pilot line was operated to produce unoriented cast films, combined with other segments of biaxially (MD-TD) oriented films. In addition, we used a single screw extruder (single layer) and report the main parameters in Table B. The MDO stage was operated to produce a uniaxially oriented film on heated and cooled rolls. This section is connected to a TD downstream tenter to make biaxially oriented films. The MDO section was designed vertically and had six rolls of 18" (457mm) diameter and 30" (762mm) face width. The draw section gap was set to 0.035" (0.889 mm) and held constant for all biaxially oriented films. Temperature and speed were precisely and independently controlled.

Table B: Extruder Parameters

In the TDO stage, the film is biaxially oriented by heating the pre-stretched MDO material (hot air oven) and drawing the film from the edge along the TD in a tenter (a series of moving clamps). Film orientation is adjusted and adjusted by a pair of divergent tracks. The preheating, stretching and annealing temperatures are set in the TDO section. The oven consists of three heated and independently controlled zones.

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

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

Table C: MDP and TDO parameters

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°C and 50±10% relative humidity (ASTM D618-08) prior to testing.

Note that some films have stripes along the machine and cross directions. These strips impart non-uniformity and film thickness variation across the web. Therefore, we target only ~1 mil film properties and exclude values outside the +/-0.2 range. The banding at the TDO clamp may be due to neck formation (longitudinal banding). A transverse strip (along the MD) is produced downstream of the apparatus at the die orifice of the extruder.

Table 4: Membrane Properties

Table 4: Membrane Properties

The present invention may appear at first glance to be similar to a concurrently filed application (related application USSN 62/945760 entitled "Biaxially Oriented Polyethylene Films" (Attorney Docket No. 2019EM494)), but note that the USSN 62/945760 sample and this comparison between samples.

Table 5: Differences in properties between the related invention and the present invention

Membrane Characterization Methods

The film thickness of the film is determined by ASTM D6988-13.

The 1% secant modulus and tensile properties, including yield strength, elongation at yield, tensile strength, and elongation at break were determined by ASTM D882-10 using the following changes: using a 5-inch clamp separation and a 1-inch sample width . The strength of the film was determined by manually slack loading the sample and pulling the sample to a specified strain of 1% of its original length at a grip separation rate (crosshead speed) of 0.5 in/min and recording the load at these points degree index. The calculation procedure is 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 stretch = maximum force/cross-sectional area.

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

• Elongation is calculated as a function of the increase in length divided by the original length times 100. Elongation = increase in length/original length x 100%. The yield point is the first point where the strain (elongation) increases without increasing the stress (force). Yield is determined by the 2% bias method.

• Tensile at 100% elongation is calculated as a function of force at 100% elongation divided by the cross-sectional area of the specimen. Stretch at 100% elongation = force/cross-sectional area at 100% elongation.

• Tensile at 200% elongation was calculated as a function of force at 200% elongation divided by the cross-sectional area of the specimen. Stretch at 200% elongation = 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 times 100, and is reported in PSI units. 1% Secant Modulus = Load at 1% Elongation/(Average Thickness (Inches) x Width) x 100.

Transparency is determined by ASTM D1746-15.

Haze is determined by ASTM D1003-13.

Gloss is determined by ASTM D2457-13.

Dart impact was determined by Phenolic Method A in accordance with ASTM D1709-16ae1.

Puncture properties were determined by ASTM D5748 using the following modifications, including peak force, peak force normalized to 1 mil thickness (peak force divided by thickness), energy to break, and energy to break normalized to 1 mil thickness (energy to rupture divided by thickness). Any film samples that are ~1 mil thick are placed in an approximately 4 inch wide ring clamp. A stainless steel custom plunger/probe, with a 3/4" tip and two 0.25 mil slides, was pressed through the sample at a constant speed of 10 in/min. After failure at five different locations selected from a standard membrane tape Obtain the results and calculate the average.

Shrinkage (in both machine direction (MD) and transverse direction (TD) directions) as a 100 cm round film along MD under a heat gun (Model HG-501A) set to an average temperature of 750°F (399°C) and TD length percent reduction measurements. The heat gun was centered two inches above the samples and heat was applied until each sample stopped shrinking.

Water Vapor Transmission Rate (WVTR) testing was performed on MOCON Permatran W-700 and W3/61 obtained from MOCON, Inc. at 100°F (37.8°C) and 100% relative humidity using ASTM F1249 with Load the sample without a specific orientation.

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

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

where η*(0.01 rad/s) and η*(50 rad/s) are the complex viscosities measured at 190°C at frequencies of 0.01 and 50 rad/s, respectively. DST parameters help to better differentiate and emphasize the branching characteristics of the samples. In fact, the higher the DST parameter, the higher the shear thinning.

SER: The Sentmanat extensional rheometer (SER) test platform and instantaneous uniaxial extensional viscosity test are described in detail in US 2018/0319907. The extensional evolution of the instantaneous extensional viscosity was investigated by a MCR501 (Anton Paar) rheometer with controlled operating speed. The linear viscoelastic envelope (LVE) was obtained by starting the steady state shear experiments.

For all samples, tensile stress growth at T=150°C with tensile rates between 0.1 and 10 s ⁻¹ exhibited a deviation from LVE. In the nonlinear region, branched and high molecular weight polymers exhibit strain hardening curves in tensile viscosity tests. Strain hardening is defined as the rapid and abrupt flattening of extensional viscosity from linear viscoelastic behavior. Therefore, this nonlinear behavior is quantified by the strain-hardening ratio (SHR), which is defined as the ratio of the maximum instantaneous extensional viscosity at 1s ^-1 to the corresponding value at 0.1s ^-1 :

A value of 0.1s ^-1 is preferred over LVE because of the choice to employ only transient stretch rather than initiate steady-state shear data in the processing. When the ratio is greater than 1, the material exhibits strain hardening.

All documents described herein are incorporated herein by reference, including any priority documents and/or test procedures, so long as they are not inconsistent with this document. While forms of the invention have been illustrated and described, as will be apparent from the foregoing general description and specific embodiments, various changes may be made without departing from the spirit and scope of the invention. Therefore, it is not intended to limit the invention thereby. Likewise, the term "comprising" is considered synonymous with the term "comprising". Likewise, whenever a component, element, or group of elements is preceded by the conjunction "comprising", it should be understood that we also consider recitation of said component, one or more elements, preceded by the conjunction "substantially" Consists of", "consisting of", "selected from the group consisting of" or "is" the same composition or group of elements, and vice versa.

Claims (26)

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,

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.

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；

(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) 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 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;

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 impact of 250g/mil or greater and a ratio of 1% secant MD/1% secant TD of 0.65 or greater.

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

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

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,

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 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.