WO2014046777A1 - Modified polyethylene compositions for films - Google Patents

Abstract

Disclosed is a branched polyethylene modifier comprising from 0.01 wt% to 10.0 wt% diene derived units, and 1.0 wt% to 20 wt% of a C₄ to C₁₀ α-olefin derived units based on the weight of the branched modifier, wherein the branched polyethylene modifier: a) has a g'_vis of less than 0.95; b) has an Mw within a range of from 50,000 g/mol to 300,000 g/mol; and c) has an Mw/Mn within the range of from 4.0 to 12.0.

Description

MODIFIED POLYETHYLENE COMPOSITIONS FOR FILMS

INVENTORS; Jianya Cheng, Pradeep P. Shirodkar, Peijun Jiang and Johannes M. Soulages

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to USSN 13/851,769 filed March 27, 2013, USSN 13/851,752 filed March 27, 2013, USSN 13/800,098, filed March 13, 2013, and to USSN 13/623,242, filed September 20, 2012.

FIELD OF THE INVENTION

[0002] The present invention relates to branched modifiers, and polyethylene compositions useful in blown films comprising an ethylene based polymer and a branched modifier.

BACKGROUND

[0003] For many polyolefin applications, including films and fibers, increased melt strength and good optical properties are desirable attributes. Higher melt strength allows fabricators to run their blown film lines at a faster rate. It also allows them to handle thicker films in applications such as geomembranes.

[0004] Typical metallocene catalyzed polyethylenes (mPE) are somewhat more difficult to process than low-density polyethylenes (LDPE) made in a high-pressure polymerization process. Generally, mPEs (which tend to have narrow molecular weight distributions and low levels of branching) require more motor power and produce higher extruder pressures to match the extrusion rate of LDPEs. Typical mPEs also have lower melt strength which, for example, adversely affects bubble stability during blown film extrusion, and are prone to melt fracture at commercial shear rates. On the other hand, mPEs exhibit superior physical properties as compared to LDPEs. In the past, various levels of LDPE have been blended with the mPE to increase melt strength, to increase shear sensitivity, i.e. to increase flow at commercial shear rates in extruders; and to reduce the tendency to melt fracture. However, these blends generally have poor mechanical properties as compared with neat mPE. It has been a challenge to improve mPEs processability without sacrificing physical properties.

[0005] Further, one of the challenges for blown film process is obtaining good processability without impairing physical properties such as dart, tear or strength. Addition of the branched modifier(s) of this invention into LLDPE resin significantly improves the processability (such as film gauge variation and bubble stability) without significant impairment of other physical properties. The effectiveness of branched modifiers allows a low level addition which in turn will retain the physical properties of the base resin. [0006] The inventors have discovered that certain branched hydrocarbon modifiers, preferably comprising dienes, will advantageously improve processability of polyethylene without significantly impacting its mechanical properties. Moreover, addition of these branched hydrocarbon modifiers provides a means to change such properties on a continuous scale, based on real-time needs, which is typically not possible due to the availability of only discrete polyethylene grades. Furthermore, a different set of relationships between processability and properties is obtained, compared to those available from traditional polyethylenes and their blends with conventional LDPE, which allows for new and advantageous properties of the fabricated articles.

[0007] References of interest include: US 7,687,580; US 6,509,431; US 6,355,757; US 6,391,998; US 6,417,281; US 6,300,451 US 6, 1 14,457; US 6,734,265; US 6, 147,180; US 6,870,010; and US 5,670,595; WO 2007/067307; WO 2002/085954; US 2007/0260016; and Guzman, et al, 56(5) AIChE Journal, 1325-1333 (2010).

SUMMARY

[0008] A branched polyethylene modifier useful in blends with linear polyethylenes such as LLDPE for forming films, the branched modifier comprising (or consisting of) from 0.01 wt% to 10.0 wt% diene derived units, and 1.0 wt% to 20 wt% of a C₄ to Cio a-olefin derived units based on the weight of the branched modifier, wherein the branched polyethylene modifier: a) has a g'_vjs of less than 0.95; b) has an Mw within a range of from 50,000 g/mol to 300,000 g/mol; and c) has an Mw/Mn within the range of from 4.0 to 12.0. Inventive compositions comprise, or preferably consist essentially of, or most preferably consist of LLDPE and the branched modifier.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a graph of Maximum Rate Increase relative to base resin vs MD-Tear for Blends O - T in Table 19.

[0010] Figure 2 is a graph of Maximum Rate Increase relative to base resin vs DART Drop for Blends O - T in Table 19.

DETAILED DESCRIPTION

[0011] This invention relates to a polyethylene-based, highly branched modifier ("branched modifier") useful in blends with other polyolefins, especially other linear polyethylene polymers, to form cast or blown films. Desirably, the branched modifier improves the processability of linear polyethylenes when blended therewith, as can be evidenced for example by a decrease in the motor load of the extruder used to extrude the linear polyethylene. The branched modifier can be described by a number of features and properties as measured. It primarily is comprised of ethylene derived units, but will also comprise from 1.0 or 2.0 or 5.0 wt% to 12 or 16 or 20 wt% of a C₄ to Cio a-olefin derived units based on the weight of the branched modifier, most preferably 1-butene, 1-hexene or 1- octene. The branched modifier also comprises from 0.01 or 0.05 or 1.0 wt% to 5.0 or 8.0 or 10.0 wt% diene derived units, preferably alpha-omega dienes, based on the weight of the branched modifier. The dienes may be selected from the group consisting of 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1, 10- undecadiene, 1, 1 1-dodecadiene, 1, 12-tridecadiene, and 1, 13-tetradecadiene, tetrahydroindene, norbornadiene also known as bicyclo-(2.2.1)-hepta-2,5-diene, dicyclopentadiene, 5-vinyl-2-norbornene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,7- cyclododecadiene, and combinations thereof. The branched modifier preferably has a density within the range of from 0.890 or 0.905 or 0.910 or 0.915 g/cm³ to 0.920 or 0.925 g/cm³.

[0012] The properties of the branched modifier can of course vary depending on the exact process used to make it, but preferably the branched modifier has the following measurable features. Certain GPC measurable features include the following: The weight average molecular weight (Mw) is preferably within a range of from 50,000 or 60,000 or 80,000 g/mol to 140,000 or 180,000 or 200,000 or 240,000 or 280,000 or 300,000 g/mol. The number average molecular weight (Mn) is preferably within a range of from 10,000 or 15,000 or 20,000 g/mol to 22,000 or 26,000 or 30,000 or 40,000 or 50,000 or 100,000 g/mol. The z- average molecular weight (Mz) is preferably greater than 200,000 or 300,000 or 400,000 or 500,000 g/mol, and more preferably within a range of from 150,000 or 200,000 or 300,000 g/mol to 500,000 or 600,000 or 800,000 or 1,000,000 or 1,500,000 or 2,000,000 g/mol. Finally, the branched modifier has a molecular weight distribution (Mw/Mn) within the range of from 4.0 or 4.5 or 5.0 to 7.0 or 8.0 or 10.0 or 12.0.

[0013] Certain DSC measurable properties include the following: The branched modifier preferably has a melting point temperature (T_m) within the range of from 95 or 100 or 110 or 1 15°C to 125 or 130 or 135°C. The branched modifier also preferably has a crystallization temperature (T_c) within the range of from 75 or 80 or 85 or 90°C to 1 10 or 1 15 or 120 or 125°C. The branched modifier also preferably has a heat of fusion (¾) within the range of from 70 or 75 or 80 J/g to 90 or 95 or 100 or 1 10 or 120 or 130 or 140 J/g.

[0014] Certain melt flow properties of the branched modifier include the following: The branched modifier preferably has a melt index (190/2.16, "I₂") of 15 g/10 min or less, 10 g/10 min or less, 5 g/10 min or less or 2 g/10 min or less, or more preferably within the range of from 0.10 or 0.20 or 0.30 or 0.80 or 1.0 g/10 min to 4 or 5 or 6 or 8 g/10 min. The branched modifier has a wide ranging high load melt index (I₂₁), but preferably has a high load melt index (190/21.6, "I₂₁") within the range of from 0.10 or 0.20 or 0.30 or 0.80 or 1.0 g/10 min to 4 or 5 or 6 or 8 or 20 or 40 or 60 or 80 or 100 or 140 or 180 or 200 g/10 min. The branched modifier has a melt index ratio (I₂₁/I₂) within a range of from 20 or 25 or 30 to 70 or 75 or 80 or 85 or 90.

[0015] Certain dynamic properties of the branched modifier include the following: The branched modifier preferably has a Complex Viscosity at 0.1 rad/sec and a temperature of 190°C within the range of from 20,000, or 50,000, or 100,000 or 150,000 Pa^»s to 300,000 or 350,000 or 400,000 or 450,000 Pa^»s. The branched modifier preferably has a Complex Viscosity at 100 rad/sec and a temperature of 190 °C within the range of from 500 or 700 Pa^»s to 5,000 or 8,000 or 10,000 or 15,000 Pa^»s. Also, the branched modifier preferably has a Phase Angle at the Complex Modulus of 10,000 Pa within the range of from 10 or 15 or 20 or 25° to 45 or 50 or 55 or 60° when the complex shear rheology is measured at a temperature of 190°C. The branched modifier preferably has a Phase Angle at the Complex Modulus of 100,000 Pa within the range of from 10 or 15° to 25 or 35 or 45° when the complex shear rheology is measured at a temperature of 190°C. Finally, the branched modifier has a level of branching indicated by the measured value of the branching index "g'_vi_s". The value for g'_vi_s is preferably less than 0.95 or 0.92 or 0.90 or 0.80 or 0.75 or 0.60, or within a range of from 0.30 or 0.40 or 0.60 or 0.70 to 0.90 or 0.95. A polyethylene is "linear" when the polyethylene has no long chain branches, typically having a g'_vi_s of 0.97 or above, preferably 0.98 or above. "Linear polyethylenes" preferably include ethylene polymers having a g'_vi_s of 0.95 or 0.97 or more, and as further described herein. Thus, a lower value for g'_vi_s indicates more branching. The inventive blends can however include blends of so-called long-chain branched LLDPEs with the branched modifier.

[0016] Shear thinning is observed for the branched modifiers and is a characteristic used to describe the modifier. Shear thinning is one of the characteristics of branched polymer due to chain entanglement and long relaxation time. Shear thinning is used as a measure of level of branching. Melt index ratio, or i/h, and shear thinning ratio (defined as a ratio of the complex shear viscosity at a frequency of 0.1 rad/s to that at a frequency of 100 rad/s) are characteristics used to describe the inventive branched modifiers. Preferred values for shear thinning are greater than 30 or 40 or 50, while preferred values for I₂₁/I₂ are greater than 20 or 30 or 40. More particularly, the shear thinning ratio is within the range of from 5 or 10 or 20 to 40 or 50 or 60 or 70 or 100 or 200 or 300, and the i/h is within the range of from 20 or 30 or 40 to 100 or 200 or 250 or 300 or 400. Notice that some values are too low to be measured for some of desirable materials, in which case hi/h is very high or not recorded. Making the Branched Modifier

[0017] The branched modifier can be made by techniques generally known in the art for making polyethylenes, especially solution, gas phase, or slurry phase polymerization processes using single-site catalysis. In particular, bridged tetrahydroindenyl zironcocenes or hafnocenes or substituted versions thereof are preferred single site catalysts when combined with known activator compounds such as perfluorinated organoboron compounds and/or aluminoxanes, most preferably methalumoxanes. As will be understood by those in the art, the identity of the catalyst and activator, their relative amounts, and the process conditions can be varied to effectuate the desired properties of the branched modifier as described above. Preferably, the catalyst composition is a dimethylsilyl-bis-(tetrahydroindenyl) zirconium dihalide or dialkyl, or dimethylsilyl-bis-(indenyl) zirconium dihalide or dialkyl, or substituted versions thereof, whereby the indenyl or tetrahydroindenyl chain may have Ci to Cio alkyl or phenyl substitutions at any one or more positions, especially the 2, 4 or 7 positions relative to the bridging position.

[0018] Desirable temperature at which to carry out the slurry phase process to make the branched modifier is within the range of from 50 or 60°C to 80 or 90 or 100 or 110°C. Hydrogen may be present in the slurry or solution process at a concentration of at least 50 ppm, or at least 100 ppm, or at least 150 ppm. Desirable temperature at which to carry out the solution phase processes to make the branched modifier is within the range from 90 or 1 10°C to 130 or 140 or 160 or 180°C. Finally, in either the slurry or solution process, desirable C₄ to Cio a-olefin comonomer concentrations in the reactor are within the range of from 0.1 or 0.5 or 1 wt% to 2 or 5 or 10 or 15 wt%, and desirable diene feed rates are within the range of from 0.01 or 0.05 or 0.01 wt% relative to ethylene feed rate to 0.1 or 0.2 or 0.5 wt% relative to ethylene feed rate.

Blends and Films incorporating the Branched Modifer

[0019] The branched modifiers are particularly useful as modifiers of "linear" polyethylenes such as LLDPEs or long chain branched LLDPEs that are used to form films. Preferably, the LDPE is absent from the inventive blends. Examples of such linear polyethylenes include those such as disclosed in US 8,399,581 and US 7,951,873, and other traditional LLDPEs or so-called long-chain branched LLDPEs known in the art. The branched modifier improves the melt strength of the linear polyethylenes as well as its processability (e.g., as evidenced by increased output relative to LLDPE alone) and its Dart Impact and Tear Strength when made into films. Inventive compositions comprise, or preferably consist essentially of, or most preferably consist of a blend of LLDPE and the branched modifier. By "consist essentially of what is meant is that the blend may also include common additives such as antioxidants, anti-slip agents, colorants and pigments, and other common additives to a level no greater than 5 wt% or 4 wt% or 3 wt% or 2 wt%.

[0020] Preferably, additives such as block, antiblock, antioxidants, pigments, fillers, processing aids, UV stabilizers, neutralizers, lubricants, surfactants and/or nucleating agents may also be present in one or more than one layer in the films. Preferred additives include silicon dioxide, titanium dioxide, polydimethylsiloxane, talc, dyes, wax, calcium sterate, carbon black, low molecular weight resins and glass beads, preferably these additives are present at from 0.1 or 1.0 ppm to 500 or 1000 ppm.

[0021] The branched modifiers are preferably present as a blend with the "linear" polyethylenes within a range of from 0.1 or 0.5 or 1.0 to 4 or 6 or 8 or 10 wt% by weight of the blend. Desirable linear polyethylenes will have an I₂ within the range from 0.5 or 1 g/10 min to 4 or 6 g/10 min and a density within the range from 0.910 or 0.915 g/cm³ to 0.920 or 0.930 g/cm³. The Haze value for such blends, or films formed from such blends, is preferably less than 50 or 40 or 30 or 20 or 10%.

[0022] Preferably, the linear polyethylene/modifier blend has a melt strength that is at least 5% higher than the melt strength of linear polyethylene used in the blend, preferably at least 10%, preferably at least 20%, preferably at least 30%, preferably at least 40%, preferably at least 50%, preferably at least 100%, preferably at least 200%, preferably at least 300%, preferably at least 400%, preferably at least 500%, preferably at least 600%, preferably at least 700%, preferably at least 800%. Desirably, the melt strength of the branched modifier is within the range of from 5 or 10 or 15 or 20 or 30 cN to 40 or 50 or 60 cN, while that of the inventive blends is within the range of from 1 or 2 or 3 cN to 5 or 8 or 12 cN.

[0023] The polyethylene blends comprising one or more linear polyethylene and one or more branched modifiers show characteristics of strain-hardening in extensional viscosity. "Strain-hardening" is observed as a sudden, abrupt upswing of the extensional viscosity in the transient extensional viscosity vs. time plot. This abrupt upswing, away from the behavior of a linear viscoleastic material, was reported in the 1960s for LDPE (J. Meissner, 8 Rheology Acta., 78 (1969)) and was attributed to the presence of long branches in the polymer. In one embodiment, the inventive modifier and polyethylene blends have strain-hardening in extensional viscosity. The "strain-hardening ratio" (SHR), which is defined as the ratio of the maximum transient extensional viscosity over three times the value of the transient zero- shear-rate viscosity at the same strain rate, for the inventive blends is preferably within the range of from 0.5 or 2.0 or 3.0 to 6.0 or 7.0 or 8.0 or 9.0 or 10.0 when the extensional viscosity is measured at a strain rate of 1 sec^-1 and at a temperature of 150°C. For the branched modifier itself, the SHR can vary greatly, but is preferably within the range of from 4.0 or 5.0 or 10 to 20 or 40 or 60 at a strain rate of 1 sec^-1 and at a temperature of 150°C.

[0024] The SHR of the blend is at least 10% higher than the SHR of the linear polyethylene used in the blend, preferably at least 20% higher, at least 30% higher, at least 50% higher, at least 100% higher, at least 500% higher, at least 800% higher, at least 1000% higher.

[0025] As mentioned, the inventive blend of the branched modifier with a linear polyethylene can improve the processability of the linear polyethylene. Evidence of this is demonstrated, for example, in the improved ability to extrude the blend as compared to the linear polyethylene alone. Preferably, the average motor load of an extruder, in extruding the blend through a die, has an average motor load at least 1% or 2% or 3% or 4% or 5% or 8% or 10% less than the average motor load in the same extruder when extruding only the same linear polyethylene (or within a range from 1 or 2 or 3 % to 5 or 6 or 10%). Overally, the output from the extruder may increase as much as 10 or 20 or 30 or 40% or more for the inventive blends relative to the linear polyethylene alone.

[0026] The branched modifier blend with linear polyethylene also preferably has a crystallization temperature (T_c) within the range of from 85 or 90 or 95°C to 110 or 1 15 or

120 or 125°C; or, more preferably, the T_c of the blend is at least 4 or 6 or 8 or 10°C or more higher than that of the branched modifier alone.

[0027] The inventive films made from the inventive blends have certain desirable properties. Certain tensile properties include the Yield Strength which is preferably within the range of from 400 or 500 or 600 or 800 psi to 1200 or 1300 or 1400 or 1500 or 1600 in the MD and TD. The Elongation at Yield is within the range of from 1 or 2 or 3 or 4% to 10 or 12 or 16% in both the MD and TD. The Tensile Strength of the inventive films is within the range of from 5000 or 5500 or 6000 or 6500 psi to 7500 or 8000 or 8500 or 9000 psi in both the MD and TD. The Elongation at Break is within the range of from 500 or 550 or 600% to 700 or 750 or 800% in both the MD and TD. The Elmendorf Tear is within the range of from 200 or 240 g/mil to 300 or 350 or 400 or 450 in the MD, and within the range of from 350 or 400 g/mil to 500 or 550 g/mil in the TD. The Dart Drop of the inventive films is within the range of from 150 or 200 g/mil to 300 or 350 or 400 g/mil.

[0028] Inventive films, especially blown films, may preferably be characterized wherein the film has an improvement in dart drop or no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent.

[0029] Finally, the Maximum Rate increase will vary from 100% to 20% when the MD Tear of films formed from LLDPE and from 0.1 or 0.5 wt% to 1.0 or 1.0 wt% of the branched modifier increases from 100 to 300 g/mil. Likewise, the Maximum Rate increase will vary from 100% to 20% when the Dart Drop of the same film increases from 400 to 700 g/mil.

[0030] Cast films may preferably be characterized where the film has at least a 10% reduction in neck-in as compared to the same composition formed into a film under the same conditions, except that the branched modifier is absent.

[0031] The various descriptive elements and numerical ranges disclosed herein for the branched modifiers and films made from the branched modifers and method of making them can be combined with other descriptive elements and numerical ranges to describe the invention(s); further, for a given element, any upper numerical limit can be combined with any lower numerical limit described herein.

[0032] Thus, described one way the present invention relates to films comprising polyethylene and a branched polyethylene modifier comprising at least 50 mol% ethylene (preferably at least 70 mol% or more, preferably at least 90 mol% or more), one or more C₄

(preferably (¾ to C₄Q comonomers (preferably 50 mol% or less, preferably 30 mol% or less, preferably from 0.5 to 30 mol%, preferably 1 to 25 mol%), and a diene having at least two polymerizable bonds (preferably from 0.001 to 10 mol%, preferably from 0.01 to 5 mol%), wherein said branched polyethylene modifier has: a) a g'_vi_s of 0.90 or less (preferably 0.85 or less, preferably 0.80 or less, preferably 0.75 or less, preferably 0.70 or less); b) an Mw of 100,000 g/mol or more, (preferably 120,000 or more, preferably 150,000 or more, preferably 200,000 or more); c) an Mw/Mn of 3.0 or more (preferably 4.0 or more, preferably 4.5 or more, preferably 5.0 or more, preferably 5.5 or more, preferably 6.0 or more, preferably 7.0 or more, preferably from 3.0 to 40); d) has an Mz/Mn of 7.0 or more (preferably 8.0 or more, preferably 10.0 or more, preferably 12.0 or more); e) has a shear thinning ratio of 40 or more (preferably 50 or more, preferably 60 or more, preferably 70 or more); f) preferably, has an Mz of 2,000,000 g/mol or less (preferably 1,800,000 or less, preferably 1,500,000 or less); and g) preferably has an I₂₁ of 20 dg/min or more (preferably 15 dg/min or more, preferably 10 dg/min or more, preferably 5 dg/min or more, ASTM 1238 21.6 kg, 190°C), where the film has an improvement in dart drop or no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the polyethylene (preferably LLDPE) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the polyethylene (preferably LLDPE) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the polyethylene (preferably LLDPE) formed into a film under the same conditions, except that the branched modifier is absent.

[0033] This invention further relates to film, preferably a blown film, comprising a blend comprising more than 25 wt% (based on the weight of the composition) of one or more linear polyethylene having a g'_vi_s of 0.97 or more and an Mw of 20,000 g/mole or more, and at least 0.1 wt% (based on the weight of the composition) of a branched polyethylene modifier where the modifier has a) a g'_vi_s of 0.90 or less; b) an Mw of 100,000 g/mol or more; c) an Mw/Mn of 3.0 or more; d) has an Mz/Mn of 7.0 or more; e) has an Mz of 2,000,000 g/mol or less; f) has a shear thinning ratio of 40 or more, where the film has an improvement in dart drop or no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the linear polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the linear polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the linear polyethylene (preferably LLDPE) formed into a film under the same conditions, except that the branched modifier is absent.

[0034] This invention also relates to a process to make a blown film comprising forming a blend into a blown film, said blend comprising:

1) branched polyethylene modifier comprising at least 50 mol% ethylene, one or more C₄ (preferably (¾ to C_4Q comonomers, and a diene having at least two polymerizable bonds, wherein said branched polyethylene modifier has: a) a g'_vi_s of 0.90 or less (preferably 0.85 or less, preferably 0.80 or less, preferably 0.75 or less, preferably 0.70 or less); b) an Mw of 100,000 g/mol or more, (preferably 120,000 or more, preferably 150,000 or more, preferably 200,000 or more); c) an Mw/Mn of 3.0 or more (preferably 4.0 or more, preferably 4.5 or more, preferably 5.0 or more, preferably 5.5 or more, preferably 6.0 or more, preferably 7.0 or more, preferably from 3.0 to 40); d) has an Mz/Mn of 7.0 or more (preferably 8.0 or more, preferably 10.0 or more, preferably 12.0 or more); e) has a shear thinning ratio of 40 or more (preferably 50 or more, preferably 60 or more, preferably 70 or more); f) preferably, has an Mz of 2,000,000 g/mol or less (preferably 1,800,000 or less, preferably 1,500,000 or less); and g) preferably has an I₂₁ of 20 dg/min or more (preferably 15 dg/min or more, preferably 10 dg/min or more, preferably 5 dg/min or more, ASTM 1238 21.6 kg, 190°C); and

2) polyethylene having a density of 0.910 g/cm³ or more, a g'_vi_s of 0.97 or more, and an Mw of 20,000 g/mol or more; where the film has an improvement in dart drop or no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the polyethylene (preferably LLDPE) formed into a film under the same conditions, except that the branched modifier is absent.

[0035] In another embodiment, this invention further relates to a film comprising a composition comprising:

1) from 99.99 wt% to 50 wt% (preferably from 75 wt% to 99.9 wt%, preferably from 90 wt% to 99.9 wt%, preferably from 95 wt% to 99.5 wt%, preferably from 96 wt% to 99.5 wt%, preferably from 97 wt% to 99.5 wt%, preferably from 98 wt% to 99 wt%), based upon the weight of the blend, of a linear polyethylene having:

a) a branching index, g'_vi_s, (determined according the procedure described in the Test Methods section below) of 0.97 or more, preferably 0.98 or more, preferably 0.99 or more; and

b) a density of 0.860 to 0.980 g/cm³ (preferably from 0.880 to 0.940 g/cm³, preferably from 0.900 to 0.935 g/cm³, preferably from 0.910 to 0.930 g/cm³, preferably from 0.920 to 0.930 g/cm³);

c) an Mw of 20,000 g/mol or more (preferably 20,000 to 2,000,000 g/mol, preferably 30,000 to 1,000,000, more preferably 40,000 to 200,000, preferably 50,000 to 750,000); and

2) from 0.01 wt% to 50 wt% (preferably from 0.1 wt% to 25 wt%, preferably from 0.1 wt% to 10 wt%, preferably from 0.5 wt% to 5 wt%, preferably from 0.5 wt% to 4 wt%, preferably from 0.5 wt% to 3 wt%, preferably from 1 wt% to 2 wt%), based upon the weight of the blend, of a branched modifier, preferably comprising a terpolymer of ethylene, a C₄ to C20 alpha-olefin, and a diene, said modifier having:

a) a g'_vi_s of 0.90 or less (preferably 0.85 or less, preferably 0.80 or less, preferably 0.75 or less, preferably 0.70 or less); b) an Mw of 100,000 g/mol or more, (preferably 120,000 or more, preferably 150,000 or more, preferably 200,000 or more); c) an Mw/Mn of 3.0 or more (preferably 4.0 or more, preferably 4.5 or more, preferably 5.0 or more, preferably 5.5 or more, preferably 6.0 or more, preferably 7.0 or more, preferably from 3.0 to 40); d) has an Mz/Mn of 7.0 or more (preferably 8.0 or more, preferably 10.0 or more, preferably 12.0 or more); e) has a shear thinning ratio of 40 or more (preferably 50 or more, preferably 60 or more, preferably 70 or more); f) preferably, has an Mz of 2,000,000 g/mol or less (preferably 1,800,000 or less, preferably 1,500,000 or less); and g) preferably has an I₂i of 20 dg/min or more (preferably 15 dg/min or more, preferably 10 dg/min or more, preferably 5 dg/min or more, ASTM 1238 21.6 kg, 190°C);

where the film has an improvement in dart drop or no greater than a 25% reduction (preferably no greater than 20%, preferably no greater than 15%) in dart drop (as measured in g/mil) as compared to the linear polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in MD Elmendorf tear or no greater than a 35% reduction (preferably no greater than 30%, preferably no greater than 25%, preferably no greater than 20%, preferably no greater than 15%) in Elmendorf tear (as measured in g/mil) as compared to the linear polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent, and the film has an improvement in maximum extrusion rate of at least 20% as compared to the linear polyethylene (preferably linear low density polyethylene) formed into a film under the same conditions, except that the branched modifier is absent (preferably at least 20%, preferably at least 30%, preferably at least 40%).

[0036] The features of the invention are described in the following non-limiting examples.

Test Methods

[0037] All test methods are as well known in the art and published in US 2013-0090433 Al.

[0038] "Melt strength" is defined as the force required to draw a molten polymer extrudate at a rate of 12 mm/s² and at an extrusion temperature of 190°C until breakage of the extrudate whereby the force is applied by take up rollers. The polymer is extruded at a velocity of 0.33 mm/s through an annular die of 2 mm diameter and 30 mm length. Melt strength values reported herein are determined using a Gottfert Rheotens tester and are reported in centi-Newtons (cN). Additional experimental parameters for determining the melt strength are listed in Table 1. For the measurements of melt strength, the resins were stabilized with 500 ppm of Irganox 1076 and 1500 ppm of Irgafosl68.

Table 1: Melt Strength test parameters

[0039] Dynamic shear melt rheological data was measured with an Advanced

Rheometrics Expansion System (ARES) using parallel plates (diameter = 25 mm) in a dynamic mode under nitrogen atmosphere. For all experiments, the rheometer was thermally stable at 190°C for at least 30 minutes before inserting compression-molded sample of resin onto the parallel plates. To determine the samples viscoelastic behavior, frequency sweeps in the range from 0.01 to 385 rad/s were carried out at a temperature of 190°C under constant strain. Depending on the molecular weight and temperature, strains of 10% and 15% were used and linearity of the response was verified. A nitrogen stream was circulated through the sample oven to minimize chain extension or cross-linking during the experiments. All the samples were compression molded at 190°C and no stabilizers were added. A sinusoidal shear strain is applied to the material. If the strain amplitude is sufficiently small the material behaves linearly. It can be shown that the resulting steady-state stress will also oscillate sinusoidally at the same frequency but will be shifted by a phase angle δ with respect to the strain wave. The stress leads the strain by δ. For purely elastic materials δ=0° (stress is in phase with strain) and for purely viscous materials, δ=90° (stress leads the strain by 90° although the stress is in phase with the strain rate). For viscoelastic materials, 0 < δ < 90. The shear thinning slope (STS) was measured using plots of the logarithm (base ten) of the dynamic viscosity versus logarithm (base ten) of the frequency. The slope is the difference in the log(dynamic viscosity) at a frequency of 100 rad/sec and the log(dynamic viscosity) at a frequency of 0.01 rad/sec divided by 4. Dynamic viscosity is also referred to as complex viscosity or dynamic shear viscosity.

[0040] Where applicable, the properties and descriptions below are intended to encompass measurements in both the machine and transverse directions. Such measurements are reported separately, with the designation "MD" indicating a measurement in the machine direction, and "TD" indicating a measurement in the transverse direction.

EXAMPLES

[0041] The present invention, while not meant to be limited by, may be better understood by reference to the following examples and tables.

Examples 1 to 4

[0042] Four branched modifiers ("modifiers") were produced in a 1 -liter autoclave reactor operated in a slurry process. The reactor system was equipped with a stirrer, an external water/steam jacket for temperature control, a regulated supply of dry nitrogen, ethylene, propylene, hydrogen and a septum inlet for introduction of other solvents, catalysts, liquid monomer, and scavenger solutions. The reactor was first washed using hot toluene and then dried and degassed thoroughly prior to use. All the solvents and monomers were purified by passing through a 1-liter basic alumina column activated at 600°C, followed by a column of molecular sieves activated at 600°C or Selexsorb CD column prior to transferring into the reactor.

[0043] Dimethylsilyl-bis-(tetrahydroindenyl) zirconium dichloride was used as metallocene Catalyst A. The metallocene was supported on silica particles according to the procedure described in US 6,476, 171 B l. In brief, a solution of 1300 ml of 30 wt% alumoxane (MAO) in toluene as determined by reference to the total Al content, which may include unhydrolyzed TMA was charged to a two gallon (7.57 Liter), jacketed glass-walled reactor, equipped with a helical ribbon blender and an auger-type shaft. 2080 ml of toluene was added and stirred. A suspension of 31.5 g metallocene catalyst in 320 ml of toluene purchased from Albemarle, was cannulated to the reactor. An additional bottle of dry toluene (250 ml) was used to rinse solid metallocene crystals into the reactor by cannula under nitrogen pressure. The mixture was allowed to stir at 69°F (20.6°C) for one hour, before being transferred to a four-liter Erlenmeyer flask under nitrogen. 1040 grams of silica (Davison MS 948, 1.65 ml/g pore volume) was charged to the reactor. Half of the solution from the 4 liter Erlenmeyer flask was then transferred back to the 2 gallon (7.57 liter) stirred glass reactor. The reaction temperature rose from 70°F (21.1°C) to 100°F (37.8°C) in a five minute exotherm. The balance of the solution in the 4 liter Erlenmeyer was subsequently added back to the glass reactor, and stirred twenty minutes. Then, toluene was added (273 ml, 238 g) to dilute the active catalyst slurry, and stirred an additional twenty-five minutes. 7 grams of antistatic agent Irgastat™ AS-990, a surface modifier made from ethoxylated stearylamine sold by Witco Chemical Corp. (7 g in 73 ml toluene), was cannulated to the reactor and the slurry mixed for thirty minutes. Removal of solvent commenced by reducing pressure to less than 18 inches of mercury (457 mmHg) while feeding a small stream of nitrogen into the bottom of the reactor and raising the temperature from 74°F (23.3°C) to 142°F (61.1°C) over a period of one hour. Then five additional hours of drying at 142°F (61.1°C) to 152°F (66.7°C) and vacuum which ranged from 5 inches to 22 inches Hg (127 to 559 mmHg) were used to dry the support and yield 1709.0 g of free-flowing active supported catalyst material. Head space gas chromatograph (HSGC) measurements showed 13,000 weight parts per million (1.3 wt%) of residual toluene. A second drying step under stronger vacuum conditions resulted in HSGC analysis measurement of residual toluene at 0.18%.

[0044] 1,9-decadiene was used as the polymerizable diene. The 1,9-decadiene was obtained from Sigma-Aldrich and was purified by first passing through an alumina column activated at high temperature under nitrogen, followed by a molecular sieve activated at high temperature under nitrogen.

[0045] In polymerization run, 2 ml of triisobutyl aluminum (TIBAL) (25 wt% in hexane, purchased from Sigma-Aldrich) solution was first added to the reactor. In sucm3ession, 400 ml of isohexane (diluent), 1-hexene, 1,9-decadiene and hydrogen were added into the reactor. All of these were conducted at room temperature. The mixture was then stirred and heated to a desired temperature. The supported catalyst was cannulated into the reactor using 200 ml of solvent, followed immediately by ethylene addition. The ethylene was fed on demand to maintain a relative constant reactor pressure during the polymerization reaction. The ethylene pressure reported in Table 2 was the difference between the reactor pressure immediately before ethylene addition and ethylene feed pressure during the polymerization. The ethylene consumption was monitored during the reaction using a mass flow meter. The polymerization reaction was terminated when desired amount of polymer was produced. Thereafter, the reactor was cooled down and unreacted monomer and diluent were vented to the atmosphere. The resulting mixture, containing mostly diluent, polymer and unreacted monomers, was collected in a collection box and first air-dried in a hood to evaporate most of the solvent, and then dried in a vacuum oven at a temperature of 90°C for 12 hours. Details of the experimental conditions, catalysts employed and the properties of the resultant polymer are listed in Table 2. Each run was repeated 3 to 5 times to produce enough material for application evaluation.

Table 2. Branched modifier produced in a slurry process

omp ex v scos ty . ra sec Pa^»s 9,283.0 749.7 1 , 1 17.9 350.5

[0046] For the measurement of branching index, g'vis, the Mark-Houwink parameters, k, are corrected for comonomer content and type without taking into account of diene content.

[0047] The complex viscosity of the branched modifier polymer produced in Examples 1 to 4 was measured at temperature 190°C over an angular frequency ranging from 0.01 to 398 rad/s. Significant shear thinning was observed. The ratio of complex viscosity at a frequency of 0.01 rad/s to the complex viscosity at a frequency of 398 rad/s is 139, 141, 160, and 62 for materials produced in Example 1, 2, 3, and 4, respectively. Examples 1 to 4 have shear thinning slope, the slope of the log (complex viscosity) versus log (frequency) curve, of -0.466, -0.468, -0.479, and -0.389, respectively. The more negative this slope, the faster the dynamic viscosity decreases as the frequency increases. These types of polymer are easily processed in high shear rate fabrication methods, such as injection molding. Large negative shear thinning slopes occur when polymers are highly branched. Significant shear thinning is also reflected in the high values of melt index ratio (defined as Ι21/Ι2)·

[0048] When the phase angle is plotted versus frequency for material made in Examples 1 to 4, the phase angles are nearly independent of frequency and a plateau is observed. The phase angels vary between 40 to 60 degrees over a frequency range from 0.01 to 398 rad/sec. This is a signature of a gel-like relaxation behavior and the critical relaxation exponent can be calculated as the ratio of the phase angle of the plateau divided by 90 degrees. The critical relaxation exponents for Examples 1 to 4 are less than 0.63. Linear polyolefins do not have plateaus in their plots of phase angle versus frequency. According to Garcia-Franco, et al, 34(10) Macromolecules 31 15-31 17 (2001) the lower the critical relaxation exponent, the more extensive the long chain branches in the sample. The critical relaxation exponents observed for the branched modifier of this invention are lower than any reported in this paper.

[0049] The phase angle is the inverse tangent of the loss modulus divided by the storage modulus. For linear polymer chains the polymer melt is fully relaxed at small frequencies or long relaxation times; the storage modulus is much smaller than the loss modulus and the phase angles are 90 degrees. For the branched modifier of Examples 1 to 4 the loss modulus is comparable to the storage modulus even at a frequency of 0.1 rad/s. The chains are unable to relax, because of the presence of significant amounts of branching.

[0050] The transient extensional viscosity of the modifier produced in Example 1 was measured at a temperature of 150°C and strain rate of 1 sec^-1. A strain-hardening ratio of 50.8 was observed.

Examples 5 to 13

[0051] Branched modifiers in Examples 5 to 13 were made in a continuous stirred-tank reactor operated in a solution process. The reactor was a 0.5-liter stainless steel autoclave reactor and was equipped with a stirrer, a water cooling/steam heating element with a temperature controller and a pressure controller. Solvents and comonomers were first purified by passing through a three-column purification system. The purification system consisted of an Oxiclear column (Model # RGP-R1-500 from Labclear) followed by a 5A and a 3 A molecular sieve column. Purification columns were regenerated periodically whenever there was evidence of lower activity of polymerization. Both the 3 A and 5A molecular sieve columns were regenerated in-house under nitrogen at a set temperature of 260°C and 315°C, respectively. The molecular sieve material was purchased from Aldrich. Oxiclear column was regenerated in the original manufacture. Ethylene was delivered as a gas solubilized in the chilled solvent/monomer mixture. The purified solvents and monomers were then chilled to -15°C by passing through a chiller before being fed into the reactor through a manifold. Solvent and monomers were mixed in the manifold and fed into the reactor through a single tube. All liquid flow rates were measured using Brooksfield mass flow controller.

[0052] The metallocenes were pre-activated with an activator of Ν,Ν-dimethyl anilinium tetrakis (heptafluoro-2-naphthyl) borate at a molar ratio of 1 : 1 in toluene. The preactivated catalyst solution was kept in an inert atmosphere with <1.5 ppm water content and was fed into the reactor by a metering pump through a separated line. Catalyst and monomer contacts took place in the reactor.

[0053] As an impurity scavenger, 200 ml of tri-n-octyl aluminum (TNOA) (25 wt% in hexane, Sigma Aldrich) was diluted in 22.83 kilogram of isohexane. The TNOA solution was stored in a 37.9-liter cylinder under nitrogen blanket. The solution was used for all polymerization runs until 90% of consumption, and then a new batch was prepared. The feed rates of the TNOA solution were adjusted in a range from 0 (no scavenger) to 4 ml per minute to achieve a maximum catalyst activity.

[0054] The reactor was first prepared by continuously 2 purging at a maximum allowed temperature, then pumping isohexane and scavenger solution through the reactor system for at least one hour. Monomers and catalyst solutions were then fed into the reactor for polymerization. Once the activity was established and the system reached equilibrium, the reactor was lined out by continuing operation of the system under the established condition for a time period of at least five times of mean residence time prior to sample collection. The resulting mixture, containing mostly solvent, polymer and unreacted monomers, was collected in a collection box. The collected samples were first air-dried in a hood to evaporate most of the solvent, and then dried in a vacuum oven at a temperature of 90°C for 12 hours. The vacuum oven dried samples were weighed to obtain yields. All the reactions were carried out at a pressure of 2 MPa.

[0055] 1,9-decediene was diluted with isohexane and fed into the reactor using a metering pump. Both ethylene (bis indenyl) zirconium dimethyl (catalyst B) and rac- dimethylsilylbis(indenyl)zirconium dimethyl (Catalyst C) were preactivated with N,N- dimethyl anilinium tetrakis (heptafluoro-2-naphthyl) borate. The polymerization process condition and some characterization data are listed in Table 3. For each polymerization run, the catalyst feed rate and scavenger fed rate were adjusted to achieve a desired conversion listed in Table 3.

Table 3. Branched modifier produced in a solution process

(degree) 38.2 39.8

Table 3. Branched modifier produced in a solution process (continued)

Modifier # 9 10 1 1 12 1

Reaction temperature (° C) 130 130 130 130 130 ethylene feed rate (slpn l) 8 8 8 8 8

1 -hexene feed rate (g/m in) 2.5 2 4 3 3

1 ,9-decadiene feed rate

(ml/min) 0.0488 0.0488 0.024 0.0488 0.0488

Catalyst Catalyst B Catalyst B Catalyst C Catalyst C Catalyst C

Yield (gram/min) 9.85 9.81 9.64 10.58 9.78

Conversion (%) 85.3% 88.8% 73.8% 88% 81.2

Catalyst efficiency (g

poly/g catalyst) 537, 182 535,000 825,905 906,944 1 ,048,784

Ethylene content (wt%) 87.2 88.7 85.1 83.8 87.4

Density (g/cm³) - - - - 0.9076

Tc (°C) 88.3 91.7 75.4 80.9 83.4

Tm (°C) 103.7 106.7 95.0 97.7 102.7

Heat of fusion (J/g) 1 12.8 123.0 97.7 100.0 1 14.2

Mn DRI (g/mol) 17,728 10,786 25,01 1 25,347 31 ,746

Mw DRI (g/mol) 101 ,280 51,964 87,916 128,813 181 ,281

Mz DRI (g/mol) 433, 198 105,012 243,019 504,459 729,567

Mn LS (g/mol) 21 ,483 22,247 27,775 39,460 71 , 1 10

Mw LS (g/mol) 174,433 55,077 105, 137 225,01 1 390,378

Mz LS (g/mol) 1,336,719 1 16,596 398, 179 1 ,350,3 19 2,248,953 g'vis 0.593 0.853 0.739 0.574 0.43

I₂ (dg/min) 12.2 6.4 0.4 <0.1 <0.1 I₂₁ (dg/min) 447.8 265.8 22.3 12.2 2.1

MIR 36.8 41.5 59.5 - -

Complex viscosity @ 0.01

rad/sec (Pa^»s) 1540 1810 75288 81589 436290

Complex viscosity @ 398

rad/sec (Pa^»s) 193 256 549.3

Complex viscosity @ 100

rad/sec (Pa^»s) 352.6 506.5 1265 899.1 1304

Complex viscosity @ 0.1

rad/sec (Pa^»s) 1214.2 2494.0 43220 37949 122420

Phase angle at

G*=100,000 Pa (degree) 44.0 36.5 33 28

[0056] The complex viscosity of the branched modifier polymer produced in Examples 5 to 10 was measured at a temperature of 190°C over an angular frequency ranging from 0.01 to 398 rad/s. Significant shear thinning was observed. The ratio of the complex viscosity at a frequency of 0.01 rad/s to the complex viscosity at a frequency of 398 rad/s was 186, 59.2, and 8 for materials produced in Examples 5, 7, and 9 respectively. The shear thinning slope, the slope of the log (complex viscosity) versus log (frequency) curve, for material produced in Examples 5, 7, and 9 were -0.494, -0.385, and -0.196, respectively. Significant shear thinning was also reflected in the high I₂₁/I₂ values. The shear thinning for material produced in Examples 1 to 1 1 are greater than 53.9*I2(^-0-⁷⁴), where I₂ is the melt index (190°C, 2.16 kg).

[0057] The transient extensional viscosity of the modifier produced in Example 5 was measured at a temperature of 150°C and a strain rate of 1 sec^-1. A strain-hardening ratio of 7.3 was observed.

[0058] A melt strength value of 36.6 cN was observed for the modifier produced in Example 5.

[0059] In the following examples, films are formed from blends of the branched modifier and other polyethylene (LDPEs and LLDPEs) such as:

• Exceed™ Polyethylene 2018 ("Exceed PE 2018"), an mLLDPE available from ExxonMobil Chemical Company (Houston, Texas), has an MI of 2.0 dg/min and a density of 0.918 g/cm³.

• Exceed™ Polyethylene 1018 ("Exceed PE 2018"), is an mLLDPE (metallocene ethylene/hexene copolymer) available from ExxonMobil Chemical Company (Houston, Texas), having an MI of 1.0 dg/min and a density of 0.918 g/cm³. • mPE-5 is an mLLDPE produced following the methods described in US 6,956,088 having a density of 0.917 g/cm³ and melt index of 0.9 dg/ min and melt flow ratio of 24.4.

• Polyethylene LD071.LR™ (also referred to as LDPE or LD071) is an LDPE available from ExxonMobil Chemical Company (Houston, Texas) having an

MI of 0.70 dg/min and a density of 0.924 g/cm³.

• Enable™ 20-10 polyethylene is a metallocene ethylene-hexene copolymer having a melt index of 1.0 dg/min (ASTM D 1238, 2.16kg, 190 °C) and density of 0.920 g/cm3.

· POL-A is a metallocene ethylene-hexene copolymer having a melt index of

0.2 dg/min (ASTM D 1238, 2.16kg, 190 °C), an I₂₁/I₂ of 7, a peak melting temperature of 127 °C and a density of 0.940 g/cm3.

Examples 14-17

[0060] The branched modifiers produced above were blended as a modifier with Exceed PE 2018. The compounding of the modifier with Exceed PE 2018 was carried out in a 1 " Haake twin screw extruder with an L/D of 15 followed by a strand pelletizer. The branched modifier was pre-mixed in solid state with Exceed PE 2018 granules. A two-step compounding process was employed to ensure proper mixing. In the first compounding step, a blend of 60% of the modifier and 40% Exceed PE 2018 was produced in the twin screw extruder. The extrudate was pelletized using a strand pelletizer and used as a master batch. The master batch was then further diluted with additional linear polyethylene to produce the inventive composition with desired concentration of branched additives in the second compounding step. An antioxidant package was added into all the compounded compositions. The antioxidant consists of 0.05 wt% of Irganox™ 1076 (available from Ciba Specialty Chemicals Corporation, Tarrytown, NY), 0.2 wt% of Weston™ 399 (available from Chemtura) and 0.08 wt% of Dynamar™ FX592DA (available from Dyneon LLC, Oakdale, MN). The concentration is the weight percent of the final blend.

[0061] The compounding extrusion conditions are as follows: Zone #1 was at 180°C; Zone #2 was at 185°C; Zone #3 was at 190°C; Die (Zone #5) was at 195°C; and the Extruder Speed (rpm) was at 55. The blend compositions and some of their properties are listed in Table 4. Table 4. Modifier Blend Compositions

[0062] The complex viscosity profile of Example 17 is similar to that of Exceed 2018 polyethylene over an angular frequency range from 0.01 to 398 rad/sec at a temperature of 190°C. No significant viscosity change was observed when 5 wt% of the branched modifier #5 was blended with Exceed™ 2018 polyethylene.

[0063] Strain-hardening was observed for all the polyethylene compositions produced in Examples 14 to 17. The thermal properties of the polyethylene compositions in the Examples 14 and 17 were measured using DSC. The crystallization peak and melting peak from DSC for Example #17 is almost overlapped with the peaks of Exceed 2018™ polyethylene. For Example #14, a two-hump crystallization peak was observed. Both the Tc and Tm are higher than that for Exceed 2018™ polyethylene.

[0064] Some of the inventive compositions were tested for film applications. Blown films were made using Haake Rheomex 252P single screw extruder in connection with a Brabender blown film die. The line contains a 1" single screw Haake extruder and a 1 " mono-layer blown film die. The screw is a 3: 1 compression ratio metering screw with a Maddock type mixing section before the metering section. The die gap is 0.022 mm. The extrusion die is also equipped with a cooling air ring on the outside of the die. The air ring is used to blow the air onto the film bubble to solidify the film. There is an air orifice in the center of the die to provide air to inflate the bubble. The line also contains two take-up nip rollers to pick up and collapse the film bubble. The film has 1.5 mil gauge and 2.8 bubble blow-up ratio (BUR). The film bubble BUR and gauge are achieved by adjusting extruder speed, take-up speed and amount of air in the bubble. The specified process conditions are listed in the Table 5 below. Table 5. Process Conditions for Blown Film Extruder

l-Al riisioii condition I nil Set point

Zone #1 temperature °C 190

Zone #2 temperature °C 195

Zone #3 temperature °C 190

Die (Zone #5) temperature °C 185

Extruder speed rpm 33

Line speed ft/min 5.9

Film gauge Mil 1.5

Layflat In 4.4

[0065] Tables 6 and 7 provide some properties of the films produced from the inventive composition. All film compositions contain 0.33 wt% of the antioxidant package described above, 5 wt% of modifier and 94.67 wt% of Exceed PE 2018 unless noted otherwise. Films with 100% Exceed PE 2018 and 5 wt% of LD071.LR are comparative. All four modifier films (FOl, F02, F03 and F04) exhibit significant improved haze property versus control Exceed 2018 (F06.) The haze level for these four modifier films is similar to 5% LD071.LR film. Samples (FOl, F02 and F04) also exhibit the improved blown film processability characterized as TD film gauge coefficient of variation in comparison to Exceed 2018. The processability improvement for the modifier samples of FOl, F02, and F04 are similar to that of 5% LD071.LR.

Table 6. Summary of blown film properties

TD 7008 7572 7482 7,326 8155

Elongation @ Brea < (%)

MD 641 649 640 697 682

TD 637 652 649 664 682

Elmendorf Tear

MD (gms/mil) 281 320 347 327 259 349

TD (gms/mil) 447 458 468 437

Total Haze (%) 16 17.7 16.0 16.2 17 48.2

Dart drop

(gms/mil) 246 225 210 263 230 329

Gauge COV 7.9% 5.4% 15.7% 6.8% 7.1% 11.6%

Averaged die

pressure (psi) 2875 2906 3007 3015 2933 3007

Averaged motor

load (N-m) 43.5 40.9 45.2 45.0 36.5 45.6

Table 7. Summary of blown film properties

Exam le # 107 H)8 l <> FI O

Exceed 2018 94.67 wt% 94.67 wt% 94.67 wt% 94.67 wt%

Modifier # 7 (5 wt%) 8 (5 wt%) 10 (5 wt%) 9 (5 wt%)

1% Secant (psi)

MD 24373 24956 22620 24007

TD 23660 24158 22256 21105

Tensile

Yield Strength(psi)

MD 1250 1294 1 184 1207

TD 1303 1312 1257 1 198

Elongation @ Yield (%)

MD 8 6 7 7

TD 6 6 7 7

Tensile Strength (psi)

MD 7398 8082 7385 7420

TD 7637 7428 7148 7389

Elongation @ Break (%)

MD 671 671 655 665

TD 652 658 651 667

Elmendorf Tear

MD (gms/mil) 361 338 368 351

TD (gms/mil) 416 427 438 431

Total Haze (%) 39.3 14.6 40.1 38.3

Dart drop (gms/mil) 337 229 299 386

Gauge COV 10.5% 13.3% 10.5% 13.3%

Averaged die 2934 2982 3037 3031 pressure (psi)

Averaged motor load

(N-m) 42.0 41.9 44.0 43.5

[0066] Table 8 summarizes the film properties for the inventive composition of the branched modifier produced in Example #5 and Exceed PE 2018. All of the compositions contain 0.33 wt% of the antioxidant package. The concentration of the modifier produced in Example #5 is listed in the table. Significant improvements in haze were observed for the films. F 13, F 14, and F 15 with 1%, 3%, and 5% modifier were produced in Example 5. The total haze is reduced from 48.2% for Exceed 2018 film to 10.7% of 1% modifier and 7.3% for 5% modifier samples. The haze values for the samples with 1 - 5% modifier produced in Example 5 is also considerably lower than 5% LD071.LR sample (F 12) The blown film processability, which is characterized by the TD gauge coefficient of variation (COV) is significantly improved (lower COV) for 1% - 5% modifier samples in comparison to Exceed PE 2018. Meanwhile the processability for the modifier addition samples is also superior to the blend with 5% LD071.LR. The film with 1% modifier (F 13) retains the dart impact property of Exceed PE 2018, while LD071.LR film (F 12) shows a substantially reduced dart impact.

Table 8. Summary of blown film properties

Example 18

[0067] All of the blend compositions for Example 18 were compounded with branched modifiers produced in examples #12 and #13 and various linear polyethylene listed in Table 8 according to the procedure described above and contain the antioxidant package (0.33 wt%) described above. The compounded blends were tested for film application. Blown films were made on a 2.5 inch Gloucester blown film. The line is equipped with a 2.5 inch extruder and 6" mono-layer circular blown film die. The extruder has 30 L/D length and has a Barrier-Maddock screw. The die gap is 60 mil. The extrusion die is also equipped with a Future Design dual lip cooling air ring on the outside of the die. The air ring is used to blow the air onto the film bubble to solidify the film. There is an air orifice in the center of the die to provide air to inflate the bubble. The line also contains the bubble cage, up-nip and secondary nip devices and collapsing frame to collapse the film bubble. The film has 1.0 mil gauge and 2.5 bubble blow-up ratio (BUR). The film bubble BUR and gauge are achieved by adjusting extruder speed, take-up speed and amount of air in the bubble. The specified process conditions are listed in the table below. The film compositions and characterization data are reported in Table 10.

Table 9. Process conditions for blown film line

Parameters I nit Set Point

Set Point - Barrel #1 °C 310

Set Point - Barrel #2 °C 410

Set Point - Barrel #3 °c 375

Set Point - Barrel #4 °c 350

Set Point - Barrel #5 °c 350

Screen Changer °c 390

Adapter °c 390

Rotator °c 390

Feed Throat °c 75

Lower Die °c 390

Upper Die °c 390

Inside Die °c 390

Upper Rotator °c 75

Standard Rate lbs/hr 188

Standard Line Speed ft/min 166

Film Gauge mil 1

Bubble Blow Up Ratio (BUE 0 2.5

Film lay flat in 23.6

Die Gap mil 60 Table 10. Summary of blown film composition and properties

Table 10 (continued). Summary of blown film composition and properties

[0068] The extrusion rates in Examples F 18, F21 , and F24 were increased while maintaining the film gauge and blow-up ratio during the film blowing process as compared with the extrusion rate of linear polyethylenes without branched modifier. The maximum extrusion rate is determined to be the extrusion rate right before the film bubble becomes unstable and the normal operation can no-longer be achieved. Likewise, the maximum line speed is determined to be the line speed right before the film bubble becomes unstable and the normal operation can no-longer be achieved. The maximum line speed (%) is ratio of the maximum line speed of a blend to the maximum line speed of the same linear polyethylene used in the blend. Significant improvements in haze were observed for the films with branched modifier. The blown film processability, which is characterized by the maximum line speed, is significantly improved. Meanwhile the processability for the blends with branched modifier is also superior to the blend with 5% LD071.LR.

[0069] For reference purposes the following data is included in Table 1 1A and 1 IB. Data in Tables 11A and 1 IB were taken from ExxonMobil's technical data sheets.

Table 11A:

Selected Physical and Mechanical Properties of ZN-LLDPE and m-LLDPE films.

Table 11B:

Selected Physical and Mechanical Properties of ZN-LLDPE and m-LLDPE films.

Example 19

[0070] Two branched polyethylene modifiers were made according to the procedure described in Examples 5-13, except that a 1 -liter autoclave reactor was used. The reaction conditions and characterization data are reported in Table 12.

Table 12. Modifier Properties

[0071] The complex viscosity of the branched modifier polymer produced in Modifier #14 and #15 was measured at a temperature of 190°C over an angular frequency ranging from 0.01 to 500 rad/s. Significant shear thinning was observed. The ratio of the complex viscosity at a frequency of 0.1 rad/s to the complex viscosity at a frequency of 100 rad/s was 216.9 and 186.5 for materials produced in Modifier #14 and #15 respectively.

[0072] The transient extensional viscosity of the modifier produced in Modifier #14 and #15 was measured at a temperature of 150°C and a strain rate of 1 sec^-1.

Polyethylene Blends

[0073] The branched polyethylene modifiers and matrix polyethylene (Exceed™ 2018 PE, Enable™ 20-10 polyethylene, or POL-A) were compounded in a 1" Haake twin screw extruder with 0.05 wt% Irganox 1076™, 0.2 wt% Weston 399™ and 0.08 wt% of FX592DA™. The Haake twin screw extruder was set at 50 rpm and the melt temperature was targeted at 190°C.

[0074] Comparative blends with 5 wt% LDPE (ExxonMobil Chemical Company, Houston, Texas LD071.LR™ PE, 0.924 g/cm3, 0.70 dg/min, 190°C, 2.16 kg) and 0.05 wt% Irganox 1076™, 0.2 wt% Weston 399™ and 0.08 wt% of FX592DA™ were also prepared under the conditions described above (referred to as Blends B, H, I, J, K and N), except that the extruder temperatures were 190°C, 195°C, 190°C, and 185°C, respectively. The blend compositions and film properties are listed in Tables 13, 14, and 15.

Table 13. Modifier LDPE Blends

tran- ar enng ato - - . - -

Table 14. Modifier Blends

Table 15. Modifier Blends

Example 20

[0075] Three branched polyethylene modifiers were made according to the procedure described in Examples 5-13, except that a 1 -liter autoclave reactor was used and the feed rate of 1 ,9-decadiene was adjusted to control the level of branching in the branched modifiers. The reaction conditions and characterization data are reported in Table 16.

Table 16. Modifier Properties

[0076] 1.7 kilograms of Modifier #16 and 2.8 kilograms of Modifier #17 were first mixed together. The mixture of modifiers #16 and #17, Modifier #18, and LDPE (LD071™) were each compounded with Exceed 2018™ polyethylene, then converted into blown films. The compounding process was conducted on a ZSK 57 mm twin screw extruder.

[0077] The blown film experiments were conducted on a Gloucester blown film line. The line contains a 2.5" single screw extruder and a 6" mono-layer blown film die. The extruder contains a barrier-Maddock type screw. The film has 1.0 mil gauge and 2.5 bubble blow-up ratio (BUR). The standard extrusion rate is 188 lbs/hr and 167 ft/min line speed. The specified process conditions are listed in Tables 17 and 18. The "maximum rate" was tested based on the bubble stability on the Gloucester blown film line. The film gauge and blow-up ratio was kept the same, while incrementally raising the extrusion rate and line speed correspondingly. The rate when the film bubble starts to become unstable is where it was stopped. The extrusion rate prior to this point is defined as the maximum rate. The film properties are shown in the Table 19.

Table 17. Blown Film Process Condition

Table 18. Film Fabrication Process Responses

Table 19. Film Properties

Table 19 (continued). Film Properties

[0078] Blend R (0.5% Modifier #18) with Exceed 2018™ PE exhibits 302 g/mil of MD- Elmendorf tear, which is close to the base resin Exceed™ 2018 PE value of 334 g/mil. Blend B has significantly lower MD-tear (203 g/mil) as compared to base resin Exceed™ 2018 PE. Likewise, Blend R has a slightly higher dart value (706 g/mil) as compared to the matrix Exceed 2018™ PE (684 g/mil), while Blend P has significantly reduced dart (399 g/mil).

[0079] Blend R's optical properties are also improved as compared to the base resin.

Table 20. Results for Neck-In of Examples 19 and 20

590 16.7%

690 16.0%

790 16.0%

290 22.7%

390 21.7%

490 21.3%

20

590 20.8%

690 22.0%

790 20.0%

Example 21

[0080] Two branched polyethylene modifiers were made according to the procedure described in Examples 5-13, except that a 1 -liter autoclave reactor was used and the feed rate of 1,9-decadiene was adjusted to control the level of branching in the branched modifiers. The reaction conditions and characterization data are reported in Table 21.

Table 21. Process to make branched modifiers and characteristics

[0081] The branched modifiers and LLDPE were first compounded with 0.33 wt% of antioxidant for cast film evaluation using the same procedure described early. Cast films of blends of LLDPE (Exceed™ 3527 LLDPE) and branched modifiers (blends are set out in Table 22) were prepared using a Haake cast extrusion unit. The unit contained a one inch extruder with a Barrier-Maddock screw. A four inch-width cast die with 1 mm die gap was attached to the extruder. The cast slit die contains a so-called coat hander shape flow channel section to evenly distribute the polymer flow from the extruder transition pipe to the slit die exit. A cast roll unit with three rolls was used to take up the cast film. The extrusion rate was kept at same (~25g/min,) while the take-off speed was tested in a range of 290 to 790 mm/min. Extrusion conditions were: Zone 1 set point 190°C, Zone 2 set point 195°C, Zone 3 set point 190°C, die 185°C, extruder speed 55 rpm, line speed 290-790 mm/min, and gauge 0.2 mm. After the polymer melt passed through the cast slit die, the polymer melt began to form a film conformed to the cast slit die shape. While the molten polymer cast film began to cool down, the film passed through three metal chill rolls in vertical formation. The polymer cast film then moved through the gaps between two pull rolls to be further solidified and to form the final gauge desired (the chill and pull rolls were at ambient temperature).

Table 22. Blends of Modifer and LLDPEs

The data indicate that addition of 1% of Modifier #19 to LLDPE (Exceed™ 3527) reduced the neck-in by 6% versus Exceed™ 3527 alone. 1% of Modifier #20 reduced the neck- in 7.7% as compared to Exceed™ 3527 alone.

Claims

A branched polyethylene modifier comprising from 0.01 wt% to 10.0 wt% diene derived units, and 1.0 wt% to 20 wt% of a C₄ to Cio a-olefin derived units based on the weight of the branched modifier, wherein the branched polyethylene modifier: a) has a g'_vis of less than 0.95; b) has an Mw within a range of from 50,000 g/mol to 300,000 g/mol; and c) has an Mw/Mn within the range of from 4.0 to 12.0.

The modifier of claim 1 , having a shear thinning ratio of 40 or more.

The modifier of any one of the previous claims, wherein the modifier has a heat of fusion (H_f) within the range of from 70 J/g to 140 J/g.

The modifier of any one of the previous claims, wherein the modifier has a melting point temperature (T_m) within the range of from 95°C to 135°C.

The modifier of any one of the previous claims, wherein the C₄ to C^_Q comonomers are one or more C₄ to CIQ a-olefin comonomers.

The modifier of any one of the previous claims, wherein the branched modifier has an Mz within a range of from 150,000 g/mol to 2,000,000 g/mol.

The modifier of any one of the previous claims, wherein the modifier has a phase angle at complex shear modulus G*=100,000 Pa of 40° or less, or within the range of from 10° to 35°.

The modifier of any one of the previous claims, wherein the diene is selected from the group consisting of: 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12- tridecadiene, 1,13-tetradecadiene, tetrahydroindene, norbornadiene also known as bicyclo-(2.2.1)-hepta-2,5-diene, dicyclopentadiene, 5-vinyl-2-norbornene, 1,4- cyclohexadiene, 1,5-cyclooctadiene, 1,7-cyclododecadiene, and combinations thereof. A blend made from the modifier of any one of the previous claims and a linear polyethylene, wherein the average motor load of an extruder, in extruding the blend through a die, has an average motor load at least 1% or 2% or 3% or 4% or 5% or 8% or 10% less than the average motor load in the same extruder when extruding only the same linear polyethylene (or within a range from 1 or 2 or 3% to 5 or 6 or 10%). A blend made from the modifier of any one of the previous claims and a linear polyethylene, wherein the melt strength of the branched modifier is within the range of from 10 cN to 60 cN, while that of the inventive blends is within the range of from 1 c to 12 cN.

1 1. A blend made from the modifier of any one of the previous claims and a linear polyethylene, wherein the modifier has a strain-hardening ratio within the range of from 1.0 to 10.0 when the extensional viscosity is measured at a strain rate of 1 sec^-1 and at a temperature of 150°C.

12. A film made from the blend of any one of claims 9 to 11.

13. The cast film of claim 12, where the film has at least a 10% or 15% reduction in neck- in as compared to the same composition formed into a film under the same conditions, except that the branched modifier is absent.

14. A blown film of the blend of claim 12, wherein the film has no greater than a 25% reduction in dart drop (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and no greater than a 35% reduction in Elmendorf tear (as measured in g/mil) as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent, and a maximum extrusion rate of at least 20% or more as compared to the polyethylene formed into a film under the same conditions, except that the branched modifier is absent.