WO2019022801A1 - Films de polyéthylène et leurs procédés de production - Google Patents

Films de polyéthylène et leurs procédés de production Download PDF

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WO2019022801A1
WO2019022801A1 PCT/US2018/027323 US2018027323W WO2019022801A1 WO 2019022801 A1 WO2019022801 A1 WO 2019022801A1 US 2018027323 W US2018027323 W US 2018027323W WO 2019022801 A1 WO2019022801 A1 WO 2019022801A1
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film
polymer
polyethylene
polyethylene polymer
density
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PCT/US2018/027323
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English (en)
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Maria J. CARBONE
Xiao-chuan WANG
Stefan B. Ohlsson
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Exxonmobil Chemical Patents Inc.
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Publication of WO2019022801A1 publication Critical patent/WO2019022801A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2203/00—Applications
    • C08L2203/16—Applications used for films

Definitions

  • This invention relates to films, and in particular, to multilayer films comprising polyethylene, methods for making such films, and silo bags made therefrom.
  • Coextruded blown films are widely used in various applications. Film properties are often subject to the combined effect of polymer compositions selected for the different layers. In order to address requirements of particular applications, film producers have to accordingly highlight certain film properties while balancing different mechanical properties repulsive to each other.
  • mPE metallocene-catalyzed polyethylene
  • the invention provides a film comprising a polymer composition, wherein the polymer composition comprises: from 10 wt% to 90 wt% of a first polyethylene polymer having one or more of the following properties: a density of from
  • MWD molecular weight distribution
  • the invention provides a film, comprising: a) two skin layers, wherein at least one of the skin layers comprises the first polyethylene; b) a core layer between the two skin layers, wherein the core layer comprises the second polyethylene, wherein the film has a normalized Elmendorf tear strength in the MD (ASTM D 1922-09) of 11.5 g/ ⁇ or greater.
  • the invention provides a method for making a film, comprising the steps of: a) preparing two skin layers, wherein at least one of the skin layer comprises the first polyethylene; b) preparing a core layer between the two skin layers, the core layer comprising the second polyethylene; and c) forming a film comprising the layers in above steps.
  • a "polymer” may be used to refer to homopolymers, copolymers, interpolymers, terpolymers, etc.
  • a “polymer” has two or more of the same or different monomer units.
  • a “homopolymer” is a polymer having monomer units that are the same.
  • a “copolymer” is a polymer having two or more monomer units that are different from each other.
  • a “terpolymer” is a polymer having three monomer units that are different from each other.
  • the term “different” as used to refer to monomer units indicates that the monomer units differ from each other by at least one atom or are different isomerically.
  • copolymer includes terpolymers and the like.
  • polymer includes copolymers and the like.
  • polyethylene polymer means a polymer or copolymer comprising at least 50 mol% ethylene units (preferably at least 70 mol% ethylene units, more preferably at least 80 mol% ethylene units, even more preferably at least 90 mol% ethylene units, even more preferably at least 95 mol% ethylene units or 100 mol% ethylene units (in the case of a homopolymer).
  • a polymer when referred to as comprising a monomer, the monomer is present in the polymer in the polymerized form of the monomer or in the derivative form of the monomer.
  • a polymer is said to comprise a certain percentage, wt%, of a monomer, that percentage of monomer is based on the total amount of monomer units in the polymer.
  • an ethylene polymer having a density of 0.910 to 0.940 g/cm 3 is referred to as a "low density polyethylene” (LDPE); an ethylene polymer having a density of 0.890 to 0.930 g/cm 3 , typically from 0.915 to 0.930 g/cm 3 , that is linear and does not contain a substantial amount of long-chain branching is referred to as "linear low density polyethylene” (LLDPE) and can be produced with conventional Ziegler-Natta catalysts, vanadium catalysts, or with metallocene catalysts in gas phase reactors, high pressure tubular reactors, and/or in slurry reactors and/or with any of the disclosed catalysts in solution reactors ("linear” means that the polyethylene has no or only a few long-chain branches, typically referred to as a g'vis of 0.97 or above, preferably 0.98 or above); and an ethylene polymer having a density of more than
  • a "second" polyethylene polymer is merely an identifier used for convenience, and shall not be construed as limitation on individual polyethylene, their relative order, or the number of polyethylenes used, unless otherwise specified herein.
  • composition "free of a component” refers to a composition substantially devoid of the component, or comprising the component in an amount of less than about 0.01 wt%, by weight of the total composition.
  • the first polyethylene polymer comprises from 70.0 mol% to or 100.0 mol% of units derived from ethylene.
  • the lower limit on the range of ethylene content may be from 70.0 mol%, 75.0 mol%, 80.0 mol%, 85.0 mol%, 90.0 mol%, 92.0 mol%, 94.0 mol%, 95.0 mol%, 96.0 mol%, 97.0 mol%, 98.0 mol%, or 99.0 mol% based on the mol% of polymer units derived from ethylene.
  • the first polyethylene polymer may have an upper ethylene limit of 80.0 mol%, 85.0 mol%, 90.0 mol%, 92.0 mol%, 94.0 mol%, 95.0 mol%, 96.0 mol%, 97.0 mol%, 98.0 mol%, 99.0 mol%, 99.5 mol%, or 100.0 mol%, based on polymer units derived from ethylene.
  • the first polyethylene polymer may have less than 50.0 mol% of polymer units derived from a C3-C20 olefin, preferably, an alpha- olefin, e.g., hexene or octene.
  • the lower limit on the range of C3-C20 olefin-content may be 25.0 mol%, 20.0 mol%, 15.0 mol%, 10.0 mol%, 8.0 mol%, 6.0 mol%, 5.0 mol%, 4.0 mol%, 3.0 mol%, 2.0 mol%, 1.0 mol%, or 0.5 mol%, based on polymer units derived from the C3- C20 olefin.
  • the upper limit on the range of C3-C20 olefin-content may be 20.0 mol%, 15.0 mol%, 10.0 mol%, 8.0 mol%, 6.0 mol%, 5.0 mol%, 4.0 mol%, 3.0 mol%, 2.0 mol%, or 1.0 mol%, based on polymer units derived from the C3 to C20 olefin. Any of the lower limits may be combined with any of the upper limits to form a range. Comonomer content is based on the total content of all monomers in the polymer.
  • the first polyethylene polymer may have minimal long chain branching (i.e., less than 1.0 long-chain branch/1000 carbon atoms, preferably particularly 0.05 to 0.50 long-chain branch/1000 carbon atoms).
  • minimal long chain branching i.e., less than 1.0 long-chain branch/1000 carbon atoms, preferably particularly 0.05 to 0.50 long-chain branch/1000 carbon atoms.
  • branching index as defined below
  • long chain branches may be present (i.e., less than 1.0 long- chain branch/1000 carbon atoms, preferably less than 0.5 long-chain branch/1000 carbon atoms, particularly 0.05 to 0.50 long-chain branch/1000 carbon atoms).
  • the first polyethylene polymers may have a density in accordance with ASTM D-4703 and ASTM D-1505/ISO 1183 of from about 0.910 to about 0.945 g/cm 3 , from about 0.912 to about 0.925 g/cm 3 , from about 0.910 to about 0.920 g/cm 3 , from about 0.915 to about 0.921 g/cm 3 , from about 0.910 to about 0.918 g/cm 3 , from about 0.912 to about 0.918 g/cm 3 , or from about 0.912 to 0.917 g/cm 3 .
  • the weight average molecular weight (M w ) of the first polyethylene polymers may be from about 15,000 to about 500,000 g/mol, from about 20,000 to about 250,000 g/mol, from about 25,000 to about 150,000 g/mol, from about 150,000 to about 400,000 g/mol, from about 200,000 to about 400,000 g/mol, or from about 250,000 to about 350,000 g/mol.
  • the first polyethylene polymers may have a molecular weight distribution (MWD) or (Mw/Mn) of from about 1.5 to about 5.0, from about 2.0 to about 4.0, from about 3.0 to about 4.0, or from about 2.5 to about 4.0.
  • the first polyethylene polymers may have a z-average molecular weight (M z ) to weight average molecular weight (M w ) greater than about 1.5, or greater than about 1.7, or greater than about 2.0. In some embodiments, this ratio is from about 1.7 to about 3.5, from about 2.0 to about 3.0, or from about 2.2 to about 3.0.
  • the first polyethylene polymers may have a melt index (MI) or (I 2 .i 6 ) as measured by ASTM D-1238-E (190°C/2.16 kg) of about 0.1 to about 300 g/10 min., about 0.1 to about 100 g/10 min., about 0.1 to about 50 g/10 min., about 0.1 g/10 min. to about 5.0 g/10 min., about 0.1 g/10 min. to about 3.0 g/10 min., about 0.1 g/10 min. to about 2.0 g/10 min., about 0.1 g/10 min. to about 1.2 g/10 min., about 0.2 g/10 min. to about 1.5 g/10 min., about 0.2 g/10 min.
  • the first polyethylene polymers may have a melt index ratio (MIR) (I21.6 /I2.16) (as defined below) of from about 10.0 to about 50.0, from about 15.0 to about 45.0, from about 20.0 to about 40.0, from about 20.0 to about 35.0, from about 22 to about 38, from about 20 to about 32, from about 25 to about 32, or from about 28 to about 30.
  • MIR melt index ratio
  • the first polyethylene polymers may contain less than 5.0 ppm hafnium, less than 2.0 ppm hafnium, less than 1.5 ppm hafnium, or less than 1.0 ppm hafnium. In other embodiments, the first polyethylene polymers may contain from about 0.01 ppm to about 2 ppm hafnium, from about 0.01 ppm to about 1.5 ppm hafnium, or from about 0.01 ppm to about 1.0 ppm hafnium.
  • the amount of hafnium is greater than the amount of zirconium in the first polyethylene polymer.
  • the ratio of hafnium to zirconium is at least about 2.0, at least about 10.0, at least about 15, at least about 17.0, at least about 20.0, at least about 25.0, at least about 50.0, at least about 100.0, at least about 200.0, or at least about 500.0 or more.
  • zirconium generally is present as an impurity in hafnium, it will be realized in some embodiments where particularly pure hafnium-containing catalysts are used, the amount of zirconium may be extremely low, resulting in a virtually undetectable or undetectable amount of zirconium in the first polyethylene polymer. Thus, the upper limit on the ratio of hafnium to zirconium in the polymer may be quite large.
  • the first polyethylene polymers may have at least a first peak and a second peak in a comonomer distribution analysis, wherein the first peak has a maximum at a log(M w ) value of 4.0 to 5.4, 4.3 to 5.0, or 4.5 to 4.7; and a TREF elution temperature of 70.0°C to 100.0°C, 80.0°C to 95.0°C, or 85.0°C to 90.0°C.
  • the second peak in the comonomer distribution analysis has a maximum at a log(M w ) value of 5.0 to 6.0, 5.3 to 5.7, or 5.4 to 5.6; and a TREF elution temperature of 40.0°C to 60.0°C, 45.0°C to 60.0°C, or 48.0°C to 54.0°C.
  • the first polyethylene polymer may have one or more of the following properties: a melt index (MI) (190°C/2.16 kg) of from about 0.1 g/10 min. to about 5.0 g/10 min.; a melt index ratio (MIR) of from about 15 to about 30; a M w of from about 20,000 to about 200,000 g/mol; a M w /M n of from about 2.0 to about 4.5; and a density of from about 0.910 to about 0.925 g/cm 3 .
  • MI melt index
  • MIR melt index ratio
  • the amount of hafnium is greater than the amount of zirconium and a ratio of hafnium to zirconium (ppm/ppm) may be at least about 2.0, at least about 10.0, at least about 15.0, at least about 17.0, at least about 20.0, or at least about 25.0.
  • the first polyethylene polymer may have a Broad Orthogonal Comonomer Distribution or "BOCD.”
  • BOCD refers to a Broad Orthogonal Composition Distribution in which the comonomer of a copolymer is incorporated predominantly in the high molecular weight chains or species of a polyolefin polymer or composition.
  • the distribution of the short chain branches can be measured, for example, using Temperature Raising Elution Fractionation (TREF) in connection with a Light Scattering (LS) detector to determine the weight average molecular weight of the molecules eluted from the TREF column at a given temperature.
  • TEZ Temperature Raising Elution Fractionation
  • LS Light Scattering
  • TREF-LS The combination of TREF and LS (TREF-LS) yields information about the breadth of the composition distribution and whether the comonomer content increases, decreases, or is uniform across the chains of different molecular weights of polymer chains.
  • BOCD has been described, for example, in U.S. Patent Nos. 8,378,043, Col. 3, line 34, bridging Col. 4, line 19, and 8,476,392, line 43, bridging Col. 16, line 54.
  • the TREF-LS data reported herein were measured using an analytical size TREF instrument (Polymerchar, Spain), with a column of the following dimension: inner diameter (ID) 7.8 mm and outer diameter (OD) 9.53 mm and a column length of 150 mm.
  • the column was filled with steel beads.
  • 0.5 mL of a 6.4% (w/v) polymer solution in orthodichlorobenzene (ODCB) containing 6 g BHT/4 L were charged onto the column and cooled from 140°C to 25°C at a constant cooling rate of 1.0°C/min. Subsequently, the ODCB was pumped through the column at a flow rate of 1.0 ml/min.
  • the column temperature was increased at a constant heating rate of 2°C/min. to elute the polymer.
  • the polymer concentration in the eluted liquid was detected by means of measuring the absorption at a wavenumber of 2857 crrr 1 using an infrared detector.
  • the concentration of the ethylene-a-olefin copolymer in the eluted liquid was calculated from the absorption and plotted as a function of temperature.
  • the molecular weight of the ethylene-a-olefin copolymer in the eluted liquid was measured by light scattering using a Minidawn Tristar light scattering detector (Wyatt, Calif , USA). The molecular weight was also plotted as a function of temperature.
  • the breadth of the composition distribution is characterized by the T75- T25 value, wherein T25 is the temperature at which 25% of the eluted polymer is obtained and T75 is the temperature at which 75% of the eluted polymer is obtained in a TREF experiment as described herein.
  • the composition distribution is further characterized by the Fso value, which is the fraction of polymer that elutes below 80°C in a TREF-LS experiment as described herein. A higher Fso value indicates a higher fraction of comonomer in the polymer molecule.
  • An orthogonal composition distribution is defined by a M60/M90 value that is greater than 1 , wherein ⁇ is the molecular weight of the polymer fraction that elutes at 60°C in a TREF-LS experiment and M90 is the molecular weight of the polymer fraction that elutes at 90°C in a TREF-LS experiment as described herein.
  • the first polyethylene polymers as described herein may have a BOCD characterized in that the T75-T25 value is 1 or greater, 2.0 or greater, 2.5 or greater, 4.0 or greater, 5.0 or greater, 7.0 or greater, 10.0 or greater, 1 1.5 or greater, 15.0 or greater, 17.5 or greater, 20.0 or greater, or 25.0 or greater, wherein T25 is the temperature at which 25% of the eluted polymer is obtained and T75 is the temperature at which 75% of the eluted polymer is obtained in a TREF experiment as described herein.
  • the first polyethylene polymers as described herein may further have a BOCD characterized in that M60/M90 value is 1.5 or greater, 2.0 or greater, 2.25 or greater, 2.50 or greater, 3.0 or greater, 3.5 or greater, 4.0 or greater, 4.5 or greater, or 5.0 or greater, wherein ⁇ is the molecular weight of the polymer fraction that elutes at 60°C in a TREF-LS experiment and M90 is the molecular weight of the polymer fraction that elutes at 90°C in a TREF-LS experiment as described herein.
  • the first polyethylene polymers as described herein may further have a BOCD characterized in that Fso value is 1 % or greater, 2% or greater, 3% or greater, 4% or greater, 5% or greater, 6% or greater, 7% or greater, 10% or greater, 1 1% or greater, 12% or greater, or 15% or greater, wherein Fso is the fraction of polymer that elutes below 80°C.
  • the melt strength of the first polyethylene polymer at a particular temperature may be determined with a Gottfert Rheotens Melt Strength Apparatus.
  • a polymer melt strand extruded from the capillary die is gripped between two counter-rotating wheels on the apparatus.
  • the take-up speed is increased at a constant acceleration of 2.4 mm/sec 2 .
  • the maximum pulling force (in the unit of cN) achieved before the strand breaks or starts to show draw-resonance is determined as the melt strength.
  • the temperature of the rheometer is set at 190°C.
  • the capillary die has a length of 30 mm and a diameter of 2 mm.
  • the polymer melt is extruded from the die at a speed of 10 mm/sec.
  • the distance between the die exit and the wheel contact point should be 122 mm.
  • the melt strength of the first polyethylene polymer may be in the range from about 1 to about 100 cN, about 1 to about 50 cN, about 1 to about 25 cN, about 3 to about 15 cN, about 4 to about 12 cN, or about 5 to about 10 cN.
  • the first polyethylene polymer has one or more of the following properties: a) a density of from 0.910 g/cm 3 to 0.945 g/cm 3 ; b) a branching index g'vis ⁇ 0.980; c) a melt index ratio (I21/I2) of from 10 to 50; d) a hafnium content of 5.0 ppm or less; and e) a ratio of hafnium to zirconium (ppm/ppm) of at least 2.
  • Suitable commercial examples of the first polyethylene polymer are commercially available from ExxonMobil Chemical Company, Houston, TX, and sold under Exceed XPTM Performance Polymer.
  • Exceed XPTM Performance Polymer offers step-out performance with respect to, for example, dart drop impact strength, flex-crack resistance, and machine direction (MD) tear, as well as maintaining stiffness at lower densities.
  • Exceed XPTM mPE also offers optimized solutions for a good balance of melt strength, toughness, stiffness, and sealing capabilities which makes this family of polymers well-suited for blown film/film solutions.
  • Second polyethylene polymers may be combined with the first polyethylene polymer described above in a blend in a film, for example, in one or more layers in a multilayer film or structure.
  • the second polyethylene polymers may include low density polyethylenes (LDPE) made using a conventional high-pressure process, linear low density poly ethylenes (LLDPE) produced using a Ziegler-Natta catalyst or a metallocene catalyst.
  • LDPE Low Density Polyethylenes
  • the LDPE used herein have an I2.16 of from 0.05 to 1.5 g/10 min.
  • the LDPE has a fractional I 2 .ie ⁇ 1.2 g/10 min. , preferably ⁇ 1.0 g/10 min. and optionally ⁇ 0.8 g/10 min.
  • the LDPE may even have an I 2 .i6 ⁇ 0.5 or ⁇ 0.25 g 10 min.
  • the LDPE with a lower I2.16, may be used in lower concentrations in the core layer to ensure that the overall I2 56 of the polymer composition as a whole remains amenable to coextrusion with the existing equipment.
  • the LDPE's may be made in a tubular or autoclave reactor.
  • the density may vary from 0.910 to 0.940 g/ciii 3 , and is preferably at least 0.920 g/cm 3 .
  • the Mw/Mn as determined by GPC DRI may be at least 3.
  • the LDPE may have a medium to broad molecular weight distribution defined herein as having an Mw/Mn as determined by GPC DRI of >4 and a high degree of long chai branching (LCB).
  • the LDPE may have an Mw/Mn as determined by GPC DRI of less than 10, preferably less than 8.
  • Suitable commercial examples of LDPE are commercially available from ExxonMobil Chemical Company, Houston, TX, and sold under ExxonMobilTM LDPE LD100BW, LD150BW, LD156BW, LD165BW, etc.
  • the metallocene LLDPE polymers are ethylene-based polymers having about 99.0 to about 80.0 wt%, 99.0 to 85.0 wt%, 99.0 to 87.5 wt%, 99.0 to 90.0 wt%, 99.0 to 92.5 wt%, 99.0 to 95.0 wt%, or 99.0 to 97.0 wt%, of polymer units derived from ethylene and about 1.0 to about 20.0 wt%, 1.0 to 15.0 wt%, 1.0 to 12.5 wt%, 1.0 to 10.0 wt%, 1.0 to 7.5 wt%, 1.0 to 5.0 wt%, or 1.0 to 3.0 wt% of polymer units derived from one or more C3 to C20 a-olefin comonomers, preferably C3 to C10 a-olefins, and more preferably C4 to Cs a-olefins.
  • the a- olefin comonomer may be linear, branched, cyclic and/or substituted, and two or more comonomers may be used, if desired.
  • suitable comonomers include propylene, butene, 1-pentene; 1-pentene with one or more methyl, ethyl, or propyl substituents; 1- hexene; 1-hexene with one or more methyl, ethyl, or propyl substituents; 1 -heptene; 1- heptene with one or more methyl, ethyl, or propyl substituents; 1-octene; 1-octene with one or more methyl, ethyl, or propyl substituents; 1-nonene; 1-nonene with one or more methyl, ethyl, or propyl substituents; ethyl, methyl, or dimethyl-substituted 1-decene; 1-do
  • the metallocene LLDPE polymer comprises from about 8 wt% to about 15 wt%, of C3 - C10 a-olefin derived units, and from about 92 wt% to about 85 wt% ethylene derived units, based upon the total weight of the polymer.
  • the metallocene LLDPE polymer comprises from about 9 wt% to about 12 wt%, of C3 - C10 a-olefin derived units, and from about 91 wt% to about 88 wt% ethylene derived units, based upon the total weight of the polymer.
  • the metallocene LLDPE polymers may have a melt index (MI), ⁇ 2.16 or simply I2 for shorthand according to ASTM D1238, condition E (190°C/2.16 kg) reported in grams per 10 minutes (g/10 mia), of > about 0.10 g/10 mia, e.g., > about 0.15 g/10 mia, > about 0.18 g/10 min., > about 0.20 g/10 mia, > about 0.22 g/10 mia, > about 0.25 g/10 mia, > about 0.28, or > about 0.30 g/10 min.
  • MI melt index
  • ASTM D12308 190°C/2.16 kg
  • the metallocene LLDPE polymers may have a melt index ( ⁇ 2.16) ⁇ about 3.0 g/10 min., ⁇ about 2.0 g/10 min., ⁇ about 1.5 g/10 min., ⁇ about 1.0 g/10 mia, ⁇ about 0.75 g/10 min., ⁇ about 0.50 g/10 mia, ⁇ about 0.40 g/10 min., ⁇ about 0.30 g/10 mia, ⁇ about 0.25 g/10 mia, ⁇ about 0.22 g/10 mia, ⁇ about 0.20 g/10 min.,
  • Ranges expressly disclosed include, but are not limited to, ranges formed by combinations any of the above-enumerated values, e.g., from about 0.1 to about 3.0, about 0.2 to about 2.0, about 0.2 to about 0.5 g/10 min., etc.
  • the metallocene LLDPE polymers may also have High Load Melt Index (HLMI), I21.6 or I21 for shorthand, measured in accordance with ASTM D-1238, condition F (190°C/21.6 kg).
  • HLMI High Load Melt Index
  • I21.6 or I21 for shorthand, measured in accordance with ASTM D-1238, condition F (190°C/21.6 kg).
  • the metallocene LLDPE polymers may have a Melt Index Ratio (MIR) which is a dimensionless number and is the ratio of the high load melt index to the melt index, or I21.6/I2.16 as described above.
  • MIR Melt Index Ratio
  • the MIR of the metallocene LLDPE polymers may be from 25 to 80, altematively, from 25 to 60, alternatively, from about 30 to about 55, and altematively, from about 35 to about 50.
  • the metallocene LLDPE polymers may have a density > about 0.905 g/cm 3 , > about 0.910 g/cm 3 , > about 0.912 g/cm 3 , > about 0.913 g/cm 3 , > about 0.915 g/cm 3 , > about 0.916 g/cm 3 , > about 0.917 g/cm 3 , > about 0.918 g/cm 3 .
  • metallocene LLDPE polymers may have a density ⁇ about 0.945 g/cm 3 , e.g., ⁇ about 0.940 g/cm 3 , ⁇ about 0.937 g/cm 3 , ⁇ about 0.935 g/cm 3 , ⁇ about 0.930 g/cm 3 , ⁇ about 0.925 g/cm 3 ,
  • Ranges expressly disclosed include, but are not limited to, ranges formed by combinations any of the above-enumerated values, e.g., from about 0.905 to about 0.945 g/cm 3 , 0.910 to about 0.935 g/cm 3 , 0.912 to 0.930 g/cm 3 , 0.916 to 0.925 g/cm 3 , 0.918 to 0.920 g/cm 3 , etc.
  • Density is determined using chips cut from plaques compression molded in accordance with ASTM D-1928 Procedure C, aged in accordance with ASTM D-618 Procedure A, and measured as specified by ASTM D-1505.
  • the metallocene LLDPE polymers may have a molecular weight distribution (MWD, defined as M w /M n ) of about 2.5 to about 5.5, preferably 3.0 to 4.0.
  • MWD molecular weight distribution
  • the melt strength may be in the range from about 1 to about 100 cN, about 1 to about 50 cN, about 1 to about 25 cN, about 3 to about 15 cN, about 4 to about 12 cN, or about 5 to about 10 cN.
  • the metallocene LLDPE polymers may also be characterized by an averaged 1% secant modulus (M) of from 10,000 to 60,000 psi (pounds per square inch), alternatively, from 20,000 to 40,000 psi, alternatively, from 20,000 to 35,000 psi, alternatively, from 25,000 to 35,000 psi, and alternatively, from 28,000 to 33,000 psi, and a relation between M and the dart drop impact strength in g/mil (DIS) complying with formula (A):
  • M secant modulus
  • DIS > 0.8 * [100 + e (11.71-0.000268 + 2.183xl0-V) ] where "e” represents 2.7183, the base Napierian logarithm, M is the averaged modulus in psi, and DIS is the 26 inch dart impact strength.
  • the DIS is preferably from about 120 to about 1000 g/mil, even more preferably, from about 150 to about 800 g/mil.
  • the branching index, g' is inversely proportional to the amount of branching. Thus, lower values for g' indicate relatively higher amounts of branching.
  • the amounts of short and long-chain branching each contribute to the branching index according to the formula: g -g'ixBxg'scB.
  • the metallocene LLDPE polymers have a g'vis of 0.85 to 0.99, particularly, 0.87 to 0.97, 0.89 to 0.97, 0.91 to 0.97, 0.93 to 0.95, or 0.97 to 0.99.
  • the metallocene LLDPE polymers may be made by any suitable polymerization method including solution polymerization, slurry polymerization, supercritical, and gas phase polymerization using supported or unsupported catalyst systems, such as a system incorporating a metallocene catalyst.
  • metallocene catalyst is defined to comprise at least one transition metal compound containing one or more substituted or unsubstituted cyclopentadienyl moiety (Cp) (typically two Cp moieties) in combination with a Group 4, 5, or 6 transition metal, such as, zirconium, hafnium, and titanium.
  • Cp substituted or unsubstituted cyclopentadienyl moiety
  • Metallocene catalysts generally require activation with a suitable co-catalyst, or activator, in order to yield an "active metallocene catalyst", i.e., an organometallic complex with a vacant coordination site that can coordinate, insert, and polymerize olefins.
  • Active catalyst systems generally include not only the metallocene complex, but also an activator, such as an alumoxane or a derivative thereof (preferably methyl alumoxane), an ionizing activator, a Lewis acid, or a combination thereof.
  • an activator such as an alumoxane or a derivative thereof (preferably methyl alumoxane), an ionizing activator, a Lewis acid, or a combination thereof.
  • Alkylalumoxanes typically methyl alumoxane and modified methylalumoxanes
  • the catalyst system may be supported on a carrier, typically an inorganic oxide or chloride or a resinous material such as, for example, polyethylene or silica.
  • Zirconium transition metal metallocene-type catalyst systems are particularly suitable.
  • metallocene catalysts and catalyst systems useful in practicing the present invention include those described in, U.S. Patent Nos. 5,466,649, 6,476, 171 , 6,225,426, and 7,951,873, and in the references cited therein, all of which are fully incorporated herein by reference.
  • Particularly useful catalyst systems include supported dimethylsilyl bis(tetrahydroindenyl) zirconium di chloride.
  • Supported polymerization catalyst may be deposited on, bonded to, contacted with, or incorporated within, adsorbed or absorbed in, or on, a support or carrier.
  • the metallocene is introduced onto a support by slurrying a presupported activator in oil, a hydrocarbon such as pentane, solvent, or non-solvent, then adding the metallocene as a solid while stirring.
  • the metallocene may be finely divided solids. Although the metallocene is typically of very low solubility in the diluting medium, it is found to distribute onto the support and be active for polymerization.
  • Very low solubilizing media such as mineral oil (e.g., KaydoTM or DrakolTM) or pentane may be used.
  • the diluent can be filtered off and the remaining solid shows polymerization capability much as would be expected if the catalyst had been prepared by traditional methods such as contacting the catalyst with methylalumoxane in toluene, contacting with the support, followed by removal of the solvent. If the diluent is volatile, such as pentane, it may be removed under vacuum or by nitrogen purge to afford an active catalyst.
  • the mixing time may be greater than 4 hours, but shorter times are suitable.
  • a continuous cycle is employed where in one part of the cycle of a reactor, a cycling gas stream, otherwise known as a recycle stream or fluidizing medium, is heated in the reactor by the heat of polymerization. This heat is removed in another part of the cycle by a cooling system external to the reactor. (See e.g.,
  • Suitable commercial polymers for the metallocene LLDPE polymer are available from ExxonMobil Chemical Company as EnableTM metallocene polyethylene (mPE) resins.
  • Z-N LLDPE Ziegler-Natta Linear Low Density Polyethylenes
  • the Z-N LLDPE is generally heterogeneously branched ethylene polymers.
  • heterogeneously branched ethylene polymer refers to a polymer having polymer units derived from ethylene and preferably at least one C3-C20 alpha-olefin and having a CDBI ⁇ 50.0%. Typically, such polymers are the result of a Ziegler-Natta polymerization process.
  • Heterogeneously branched ethylene polymers differ from the homogeneously branched ethylene polymers primarily in their branching distribution.
  • heterogeneously branched LLDPE polymers have a distribution of branching, including a highly branched portion (similar to a very low density polyethylene), a medium branched portion (similar to a medium branched polyethylene) and an essentially linear portion (similar to linear homopolymer polyethylene). The amount of each of these fractions varies depending upon the whole polymer properties desired. For example, a linear homopolymer polyethylene polymer has neither branched nor highly branched fractions, but is linear.
  • Heterogeneously branched ethylene polymer polymers typically have a CDBI ⁇ 50.0%, preferably ⁇ 45.0%, ⁇ 40.0%, ⁇ 35.0%, ⁇ 30.0%, ⁇ 25.0%, or ⁇ 20.0%.
  • the CDBI of the heterogeneously branched ethylene polymer is 20.0 to ⁇ 50.0%, 20.0 to 45.0%, 20.0 to 35.0%, 20.0 to 30.0%, 20.0 to 25.0%, 25.0 to 30.0%, 25.0 to 35.0%, 25.0 to 40.0%, 25.0 to 45.0%, 30.0 to 35.0%, 30.0 to 40.0%, 30.0 to 45.0%, 30.0 to ⁇ 50.0%, 35.0 to 40.0%, 35.0 to ⁇ 50.0%, 40.0 to 45.0%, or 40.0 to ⁇ 50.0%.
  • the heterogeneously branched ethylene polymer typically comprises 80 to 100 mol% of polymer units derived from ethylene and 0 to 20.0 mol% of polymer units derived from at least one C3 to C20 alpha-olefin, preferably the alpha olefin has 4 to 8 carbon atoms.
  • the content of comonomer is determined based on the mole fraction based on the content of all monomers in the polymer.
  • the content of polymer units derived from alpha-olefin in the heterogeneously branched ethylene polymer may be any amount consistent with the above ranges for ethylene. Some preferred amounts are 2.0 to 20.0 mol%, 2.0 to 15.0 mol%, or 5.0 to 10.0 mol%, particularly where the polymer units are derived from one or more C4-C8 alpha-olefins, more particularly butene-1, hexene-1, or octene-1.
  • Heterogeneously branched ethylene polymers may have a density ⁇ 0.950 g/cm 3 , preferably ⁇ 0.940 g/cm 3 , particularly from 0.915 to about 0.950 g/cm 3 , preferably 0.920 to 0.940 g/cm 3 .
  • the melt index, h. ie, according to ASTM D-1238-E (190°C/2.16 kg) of the heterogeneously branched ethylene polymer is generally from about 0.1 g/10 min. to about 100.0 g/10 min.
  • Suitable heterogeneously branched ethylene polymers include ExxonMobilTM Linear Low Density Polyethylene (LLDPE) available from ExxonMobil Chemical Company, Houston, TX.
  • LLDPE Linear Low Density Polyethylene
  • the third polyethylene polymers are ethylene-based polymers comprising > 50.0 wt% of polymer units derived from ethylene and ⁇ 50.0 wt% preferably 1.0 wt% to 35.0 wt%, even more preferably 1.0 wt% to 6.0 wt% of polymer units derived from a C3 to C20 alpha-olefin comonomer (for example, hexene or octene).
  • the third polyethylene polymer may have a density of > about 0.910 g/cm 3 , > about 0.915 g/cm 3 , > about 0.920 g/cm 3 , > about 0.925 g/cm 3 , > about 0.930 g/cm 3 , or > about 0.940 g/cm 3 .
  • the second polyethylene polymer may have a density of ⁇ about 0.950 g/cm 3 , e.g., ⁇ about 0.940 g/cm 3 , ⁇ about 0.930 g/cm 3 , ⁇ about 0.925 g/cm 3 , ⁇ about 0.920 g/cm 3 , or ⁇ about 0.915 g/cm 3 .
  • Ranges expressly disclosed include ranges formed by combinations any of the above-enumerated values, e.g., 0.910 to 0.950 g/cm 3 , 0.910 to 0.930 g/cm 3 , 0.910 to 0.925 g/cm 3 , etc.
  • Density is determined using chips cut from plaques compression molded in accordance with ASTM D-1928 Procedure C, aged in accordance with ASTM D-618 Procedure A, and measured as specified by ASTM D-1505.
  • the third polyethylene polymer may have a melt index (I2.16) according to ASTM D1238 (190°C/2.16 kg) of > about 0.5 g/10 min., e.g., > about 0.5 g/10 min., > about 0.7 g/10 min., > about 0.9 g/10 min., > about 1.1 g/10 min., > about 1.3 g/10 min., > about 1.5 g/10 min., or > about 1.8 g/10 min.
  • a melt index I2.16 according to ASTM D1238 (190°C/2.16 kg) of > about 0.5 g/10 min., e.g., > about 0.5 g/10 min., > about 0.7 g/10 min., > about 0.9 g/10 min., > about 1.1 g/10 min., > about 1.3 g/10 min., > about 1.5 g/10 min., or > about 1.8 g/10 min.
  • the melt index (I2.16) may be ⁇ about 8.0 g/10 min., ⁇ about 7.5 g/10 min., ⁇ about 5.0 g/10 min., ⁇ about 4.5 g/10 min., ⁇ about 3.5 g/10 min., ⁇ about 3.0 g/10 min., ⁇ about 2.0 g/10 min., e.g., ⁇ about 1.8 g/10 min., ⁇ about 1.5 g/10 min., ⁇ about 1.3 g/10 min., ⁇ about 1.1 g/10 min., ⁇ about 0.9 g/10 min., or ⁇ about 0.7 g/10 min., 0.5 to 2.0 g/10 min., particularly 0.75 to 1.5 g/10 min.
  • Ranges expressly disclosed include ranges formed by combinations any of the above-enumerated values, e.g., about 0.5 to about 8.0 g/10 min., about 0.7 to about 1.8 g/10 min., about 0.9 to about 1.5 g/10 min., about 0.9 to 1.3, about 0.9 to 1.1 g/10 min., about 1.0 g/10 min., etc.
  • the third polyethylene polymer may have a density of 0.910 to 0.920 g/cm 3 , a melt index (b.ie) of 0.5 to 8.0 g/10 min., and a CDBI of 60.0% to 80.0%, preferably between 65% and 80%.
  • Suitable third polyethylene polymers are available from ExxonMobil Chemical Company under the trade name ExceedTM metallocene (mPE) resins.
  • the MIR for Exceed materials will typically be from about 15 to about 20.
  • the films may include monolayer and multilayer films comprising polymer compositions made from blends of the polymers described above or multilayer films of two or more layers comprising a "neat" polymer or a blend of the polymers described above, optionally, blended with other polymers, additives, processing aids etc.
  • the polymer compositions comprise from 10 wt% to 90 wt%, 20 wt% to 80 wt%, or 30 wt% to 70 wt%, of the first polyethylene polymer, and 90 wt% to 10 wt%, 80 wt% to 20 wt%, or 70 wt% to 30 wt%, of the second polyethylene polymer.
  • the film may comprise two or more layers, such as three to nine layers, preferably, three to five layers.
  • the two or more layers may comprise at least one skin layer, a core layer, and optionally, one or more intermediary layers.
  • Each layer may comprise a "neat" polymer with optional processing aids and/or additives or may comprise a blend of polymers with optional processing aids and/or additives.
  • the at least one of the skin layer, the core layer, or optional intermediary layer may comprise from 1 wt% to 100 wt%, from 30 wt% to 100 wt%, from 40 wt% to 100 wt%, from 50 wt% to 100 wt%, from 60 wt% to 100 wt%, from 65 wt% to 100 wt%, from 70 wt% to 100 wt%, from 75 wt% to 100 wt%, from 85 wt% to 100 wt%, or from 90 wt% to 100 wt%, of the polyethylene polymer, based upon the total weight of the respective skin layer, the core layer, or optional intermediary layer.
  • the first antioxidant comprises one or more antioxidants. They include, but are not limited to, hindered phenols, for example, octadecyl-3-(3,5-di-tert.butyl-4- hydroxyphenyl)-propionate (CAS 002082-79-3) commercially available as IRGANOXTM 1076, pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS 6683- 19-8) commercially available as IRGANOXTM 1010; and combinations thereof.
  • hindered phenols for example, octadecyl-3-(3,5-di-tert.butyl-4- hydroxyphenyl)-propionate (CAS 002082-79-3) commercially available as IRGANOXTM 1076, pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4
  • They may be combined with one or more polymers in range from 100 to 4000 parts by weight of the first antioxidant, based on one million parts of the polymer or polymer composition; alternatively, from 250 to 3000 parts by weight of the first antioxidant, based on one million parts of the polymer or polymer composition, alternatively, from 500 to 2500 parts by weight of the first antioxidant, based on one million parts of the polymer or polymer composition, alternatively, from 750 to 2500 parts by weight of the first antioxidant, based on one million parts of the polymer or polymer composition, alternatively, from 750 to 2000 parts by weight of the first antioxidant, based on one million parts of the polymer or polymer composition, and alternatively, from 1000 to 2000 parts by weight of the first antioxidant, based on one million parts of the polymer or polymer composition.
  • the second antioxidant comprises one or more antioxidants. They include, but are not limited to, liquid phosphites, such as C2-C7, preferably C2-C4, and alkyl aryl phosphites mixed structures. Non-limiting examples include mono-amylphenyl phosphites, di- amylphenyl phosphites, dimethylpropyl phosphites, 2-methylbutanyl phosphites, and combinations thereof.
  • the second antioxidant may be combined with one or more polymers in the range from 100 to 4000 parts by weight of the second antioxidant, based on one million parts of the polymer or polymer composition; alternatively, from 250 to 3000 parts by weight of the second antioxidant, based on one million parts of the polymer or polymer composition, alternatively, from 300 to 2000 parts by weight of the second antioxidant, based on one million parts of the polymer or polymer composition, alternatively, from 400 to 1450 parts by weight of the second antioxidant, based on one million parts of the polymer or polymer composition, alternatively, from 425 to 1650 parts by weight of the second antioxidant, based on one million parts of the polymer or polymer composition, and alternatively, from 1 to 450 parts by weight of the second antioxidant, based on one million parts of the polymer or polymer composition.
  • polymers and/or compositions comprising the first antioxidant and/or the second antioxidant described above may be used in combination with the following neutralizing agents, additional additives and other components.
  • One or more neutralizing agents include, but are not limited to, calcium stearate, zinc stearate, calcium oxide, synthetic hydrotalcite, such as DHT4A, and combinations thereof.
  • Additional additives and other components include, but are limited to, fillers (especially, silica, glass fibers, talc, etc.) colorants or dyes, pigments, color enhancers, whitening agents, cavitation agents, anti-slip agents, lubricants, plasticizers, processing aids, antistatic agents, antifogging agents, nucleating agents, stabilizers, mold release agents, and other antioxidants (for example, hindered amines and phosphates).
  • Nucleating agents include, for example, sodium benzoate and talc.
  • Slip agents include, for example, oleamide and erucamide.
  • the one or more layers or the cast films cast films may comprise one or more of fillers, pigments, slip additives/agents, colorants or dyes, color enhancers, whitening agents, cavitation agents, lubricants, plasticizers, processing aids, antifogging agents, nucleating agents, stabilizers, mold release agents, or antioxidants.
  • polyethylene polymers and the polymer compositions described above may be formed into monolayer or multilayer films.
  • a film comprising a polymer composition, wherein the polymer composition comprises: from 10 wt% to 90 wt% of a first polyethylene polymer having one or more of the following properties: a density of from 0.910 g/cm 3 to 0.945 g/cm 3 , a branching index g'vis ⁇ 0.980, a melt index ratio (I21.6 I2.
  • ⁇ of from 10 to 50; and from 90 wt% to 10 wt% of a second polyethylene having one or more of the following properties: a density of from 0.910 to 0.940 g/cm 3 ; a melt index I2.16 of from about 0.1 to about 1.5 g/10 min.; a molecular weight distribution (MWD) Mw/Mn of from about 3.0 to about 15.0; wherein the film has an Elmendorf tear strength in the MD (ASTM D 1922-09) of 11.5 g/ ⁇ , 12.0g ⁇ m, 13.0g ⁇ m, 14g ⁇ m, 15 g/ ⁇ , 16 g/ ⁇ , 17 g/ ⁇ , 18 g/ ⁇ , 19 g/ ⁇ , 20 g/ ⁇ , or greater.
  • the film described herein may have an A/X/A structure wherein A are skin layers and X represents the core layer.
  • the composition of the A layers may be the same or different, but conform to the limitations set out herein.
  • the two skin layers A are identical.
  • a film comprising: a) two skin layers, wherein at least one of the skin layers comprises a first polyethylene polymer having one or more of the following properties: a density of from 0.910 g/cm 3 to 0.945 g/cm 3 ; a branching index g'vis ⁇ 0.980; a melt index ratio (I21.6/I2.16) of from 10 to 50; b) a core layer between the two skin layers, wherein the core layer comprises a second polyethylene polymer having one or more of the following properties: a density of from 0.910 to 0.940 g/cm 3 ; a melt index I2.16 of from about 0.1 to about 1.5 g/10 min.; and a molecular weight distribution (MWD) Mw/Mn of from about 3.0 to about 15.0; wherein the multilayer film has a normalized Elmendorf tear strength in the MD (ASTM D 1922-09) of 11.0 g/ ⁇ or greater.
  • the film has a normalized Elmendorf tear strength (ASTM D 1922) in the Machine Direction of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, greater than a film free of the second polyethylene polymer.
  • ASTM D 1922 normalized Elmendorf tear strength
  • the multilayer film described herein may have an A/B/X/B/A structure, that is further comprises two sub-skin layers B each between the core layer X and each skin layer A, wherein at least one of the sub-skin layers comprises a third polyethylene.
  • the two skin layers A are identical and/or the two sub-skin layers B are identical.
  • the third polyethylene polymer has a density of 0.910 to 0.920 g/cm 3 , a melt index (I 2 .ie) of 0.5 to 8.0 g/10 min., and a CDBI of 60.0% to 80.0%.
  • the two skin layers have in a total thickness of at most about 50% of the total thickness of the five-layer film and the two subskin layers have a total thickness of at most about 60% of the total thickness of the five-layer film. More preferably, the five-layer film has a total thickness of about 15 to about 250 ⁇ , preferably 50 to about 200 ⁇ , more preferably about 80 to about 150 ⁇ .
  • the films of the present invention may be adapted to form flexible films for a wide variety of applications, such as, cling film, low stretch film, non-stretch wrapping film, pallet shrink, over-wrap, agricultural, collation shrink film and laminated films, including stand-up pouches.
  • the film structures that may be used for bags are prepared such as sacks, trash bags and liners, industrial liners, produce bags, and, especially, heavy duty bags.
  • the bags may be made on vertical or horizontal form, fill and seal equipment.
  • the film may be used in flexible packaging, food packaging, e.g., fresh cut produce packaging, frozen food packaging, bundling, packaging and unitizing a variety of products.
  • the film can be used in silo bags, included but not limited to the storage of agricultural products.
  • a method for making a film comprising the steps of:
  • the core layer comprising a second polyethylene polymer
  • the method further comprises a step a-1) between steps a) and b): a-1) preparing two sub-skin layers each between the core layer and each skin layer, wherein at least one of the sub-skin layers comprises a third polyethylene having a density of 0.910 to 0.920 g/cm 3 , a melt index (h.ie) of 0.5 to 8.0 g/10 min., and a CDBI of 60.0% to 80.0%.
  • the films described herein may be formed by any of the conventional techniques known in the art including blown extrusion, cast extrusion, coextrusion, blow molding, casting, and extrusion blow molding.
  • the films of the present invention may be formed by using blown techniques, i.e., to form a blown film.
  • the composition described herein can be extruded in a molten state through an annular die and then blown and cooled to form a tubular, blown film, which can then be axially slit and unfolded to form a flat film.
  • blown films can be prepared as follows. The polymer composition is introduced into the feed hopper of an extruder, such as a 50 mm extruder that is water-cooled, resistance heated, and has an L/D ratio of 30: 1.
  • the film can be produced using a 28 cm W&H die with a 1.4 mm die gap, along with a W&H dual air ring and internal bubble cooling.
  • the film is extruded through the die into a film cooled by blowing air onto the surface of the film.
  • the film is drawn from the die typically forming a cylindrical film that is cooled, collapsed and, optionally, subjected to a desired auxiliary process, such as slitting, treating, sealing, or printing.
  • Typical melt temperatures are from about 180°C to about 230°C.
  • Blown film rates are generally from about 3 to about 25 kilograms per hour per inch (about 4.35 to about 26.1 1 kilograms per hour per centimeter) of die circumference.
  • the finished film can be wound into rolls for later processing.
  • a particular blown film process and apparatus suitable for forming films according to embodiments of the present invention is described in U.S. Patent No. 5,569,693. Of course, other blown film forming methods can also be used.
  • compositions prepared as described herein are also suited for the manufacture of blown film in a high-stalk extrusion process.
  • a polyethylene melt is fed through a gap (typically 0.5 to 1.6 mm) in an annular die attached to an extruder and forms a tube of molten polymer which is moved vertically upward.
  • the initial diameter of the molten tube is approximately the same as that of the annular die.
  • Pressurized air is fed to the interior of the tube to maintain a constant air volume inside the bubble. This air pressure results in a rapid 3-to-9-fold increase of the tube diameter which occurs at a height of approximately 5 to 10 times the die diameter above the exit point of the tube from the die.
  • the increase in the tube diameter is accompanied by a reduction of its wall thickness to a final value ranging from approximately 10 to 50 ⁇ and by a development of biaxial orientation in the melt.
  • the expanded molten tube is rapidly cooled (which induces crystallization of the polymer), collapsed between a pair of nip rolls and wound onto a film roll.
  • the film may be pulled upwards by, for example, pinch rollers after exiting from the die and is simultaneously inflated and stretched transversely sideways to an extent that can be quantified by the blow up ratio (BUR).
  • BUR blow up ratio
  • the inflation provides TD stretch, while the upwards pull by the pinch rollers provides MD stretch.
  • the location at which further MD or TD orientation stops is generally referred to as the "frost line" because of the development of haze at that location.
  • Variables in this process that determine the ultimate film properties include the die gap, the BUR and TD stretch, the take up speed and MD stretch and the frost line height. Certain factors tend to limit production speed and are largely determined by the polymer rheology including the shear sensitivity which determines the maximum output and the melt tension which limits the bubble stability, BUR and take up speed.
  • a laminate structure with the inventive film prepared as described herein can be formed by lamination to a substrate film using any process known in the art, including solvent based adhesive lamination, solvent less adhesive lamination, extrusion lamination, heat lamination, etc.
  • any of the polymers and compositions in combination with the additives and other components described herein may be used in a variety of end-use applications. Such end uses may be produced by methods known in the art. Exemplary end-use applications include but are not limited to films.
  • a film in a film extrusion process, a film is extruded through a slit onto a chilled, highly polished turning roll, where it is quenched from one side. The speed of the roller controls the draw ratio and final film thickness. The film is then sent to a second roller for cooling on the other side. Finally, it passes through a system of rollers and is wound onto a roll.
  • two, three, or more films are coextruded through two or more slits onto a chilled, highly polished turning roll, the coextruded film is quenched from one side.
  • the speed of the roller controls the draw ratio and final coextruded film thickness.
  • the coextruded film is then sent to a second roller for cooling on the other side. Finally, it passes through a system of rollers and is wound onto a roll.
  • Density is measured by density-gradient column, as described in ASTM D1505, on a compression-molded specimen that has been slowly cooled to room temperature (i.e., over a period of 10 minutes or more) and allowed to age for a sufficient time that the density is constant within +/- 0.001 g/cm 3 .
  • the units for density are g/cm 3 .
  • MI Melt Index
  • h ie Melt Index
  • MIR Melt Index Ratio
  • M Molecular Weight Distribution
  • M w , M z , and M n are determined by Gel Permeation Chromatography. The measurements proceed as follows. Gel Permeation Chromatography (Agilent PL-220), equipped with three in-line detectors, a differential refractive index detector (DRI), a light scattering (LS) detector, and a viscometer, is used. Experimental details, including detector calibration, are described in: T. Sun, P. Brant, R. R. Chance, and W. W. Graessley, Macromolecules, Volume 34, Number 19, pp. 6812-6820, (2001).
  • DRI differential refractive index detector
  • LS light scattering
  • Polymer solutions are prepared by placing dry polymer in a glass container, adding the desired amount of TCB, then heating the mixture at 160°C with continuous shaking for about 2 hours. All quantities are measured gravimetrically.
  • the TCB densities used to express the polymer concentration in mass/volume units are 1.463 g/ml at about 21°C and 1.284 g/ml at 145°C.
  • the injection concentration is from 0.5 to 2.0 mg/ml, with lower concentrations being used for higher molecular weight samples.
  • the DRI detector and the viscometer Prior to running each sample, the DRI detector and the viscometer are purged. The flow rate in the apparatus is then increased to 0.5 ml/minute, and the DRI is allowed to stabilize for 8 hours before injecting the first sample.
  • the LS laser is turned on at least 1 to 1.5 hours before running the samples.
  • concentration, c, at each point in the chromatogram is calculated from the baseline-subtracted DRI signal, IQRJ, using the following equation: where KJ ⁇ J is a constant determined by calibrating the DRI, and (dn/dc) is the refractive index increment for the system.
  • Units on parameters throughout this description of the GPC-3D method are such that concentration is expressed in g/cm 3 , molecular weight is expressed in g/mole, and intrinsic viscosity is expressed in dL/g.
  • the LS detector is a Wyatt Technology High Temperature DAWN HELEOS.
  • M molecular weight at each point in the chromatogram is determined by analyzing the LS output using the Zimm model for static light scattering (M.B. Huglin, LIGHT SCATTERING FROM POLYMER SOLUTIONS, Academic Press, 1971):
  • AR(9) is the measured excess Rayleigh scattering intensity at scattering angle ⁇
  • c is the polymer concentration determined from the DRI analysis
  • A2 is the second virial coefficient
  • ⁇ ( ⁇ ) is the form factor for a monodisperse random coil
  • Ko is the optical constant for the system:
  • NA Avogadro's number
  • (dn/dc) the refractive index increment for the system, which take the same value as the one obtained from DRI method.
  • a high temperature Viscotek Corporation viscometer which has four capillaries arranged in a Wheatstone bridge configuration with two pressure transducers, is used to determine specific viscosity.
  • One transducer measures the total pressure drop across the detector, and the other, positioned between the two sides of the bridge, measures a differential pressure.
  • the specific viscosity, ⁇ 5 for the solution flowing through the viscometer is calculated from their outputs.
  • the average intrinsic viscosity, h] a vg > °f me sample is calculated by:
  • Mv is the viscosity-average molecular weight based on molecular weights determined by LS analysis.
  • Elmendorf Tear Strength in the MD is measured based on ASTM D 1922-09 using the Pro Tear Electronic Elmendorf Tester 60-2600 from Thwing- Albert Instrument Co. and measures the energy required to continue a pre-cut tear in the test sample. Samples are cut across the web using the constant radius tear die and are free of any visible defects (e.g., die lines, gels, etc.). Normalized Elmendorf Tear Strength in the MD (g/ ⁇ ) is calculated through Elmendorf Tear Strength in the MD divided by the thickness of films.
  • Example 1-1 illustrates improved tear strength demonstrated by a 3-layer film made from the inventive polymer composition described herein in comparison with comparative example 1-2.
  • the two examples were prepared on a coextrusion blown film line with a BUR of 2.5 and output 220kg/h.
  • Polymer and additive products used in the samples include: the first polyethylene PEl-1 (density: 0.916 g/cm 3 , MI: 0.5 g/10 min., hafnium content: less than 5 ppm, ExxonMobil Chemical Company, Houston, Texas, USA), the first polyethylene PE1-2 (density: 0.918 g/cm 3 , MI: 0.5 g/10 min., hafnium content: less than 5 ppm, ExxonMobil Chemical Company, Houston, Texas, USA), the second polyethylene LDPE PE2-1 (density: 0.922 g/cm 3 , MI: 0.33 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), the third polyethylene catalyzed by metallocene PE3-1 (density: 0.912 g/cm 3 , MI: 1.0 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), POLYBATCHTM F15 antiblock agent (A.
  • the five examples were prepared on a coextrusion blown film line with a BUR of 2.5 and output 220kg/h.
  • Polymer and additive products used in the samples include: the first polyethylene PEl-1 (density: 0.916 g/cm 3 , MI: 0.5 g/10 min., hafnium content: less than 5 ppm, ExxonMobil Chemical Company, Houston, Texas, USA), the first polyethylene PE1-2 (density: 0.918 g/cm 3 , MI: 0.5 g/10 min., hafnium content: less than 5 ppm, ExxonMobil Chemical Company, Houston, Texas, USA), the second polyethylene LDPE PE2-1 (density: 0.922 g/cm 3 , MI: 0.33 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), the third polyethylene catalyzed by metallocene PE3-1 (density: 0.912 g/cm 3 , MI: 1.0 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), POLYBATCHTM F15 antiblock agent (A.
  • Example 3-1 illustrates improved tear strength demonstrated by a 3-layer film made from the inventive composition described herein in comparison with comparative examples 3-2 and 3-3.
  • the three examples were prepared on a coextrusion blown film line with a BUR of 2.5 and output 220kg/h.
  • Polymer and additive products used in the samples include: the first polyethylene PEl-1 (density: 0.916 g/cm 3 , MI: 0.5 g/10 min., hafnium content: less than 5 ppm, ExxonMobil Chemical Company, Houston, Texas, USA), the second polyethylene mLLDPE PE2-2 (density: 0.935 g/cm 3 , MI: 0.5 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), the third polyethylene catalyzed by metallocene PE3-1 (density: 0.912 g/cm 3 , MI: 1.0 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), POLYBATCHTM F15 antiblock agent (A.
  • Examples 4-1 and 4-2 illustrate improved tear strength demonstrated by a 5-layer film made from the inventive composition described herein in comparison with comparative examples 4-3 and 4-4.
  • the four examples were prepared on a coextrusion blown film line with a BUR of 2.5 and output 220kg/h.
  • Polymer and additive products used in the samples include: the first polyethylene PEl-1 (density: 0.916 g/cm 3 , MI: 0.5 g/10 min., hafnium content: less than 5 ppm, ExxonMobil Chemical Company, Houston, Texas, USA), the second polyethylene Z-N LLDPE PE2-3 (density: 0.918 g/cm 3 , MI: 1.0 g/10 min., ExxonMobil Chemical Company, Houston, Texas, USA), POLYBATCHTM F15 antiblock agent (A. Schulman, Fairlawn, Ohio, USA), and POLYWHITETM B8750 masterbatch (A. Schulman, Fairlawn, Ohio, USA).
  • ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited.
  • ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited.
  • within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

Abstract

L'invention concerne des films produits à partir de polymères de type polyéthylène obtenu par catalyse métallocène, éventuellement avec d'autres polymères, ainsi que des procédés de production associés.
PCT/US2018/027323 2017-07-24 2018-04-12 Films de polyéthylène et leurs procédés de production WO2019022801A1 (fr)

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WO2021216280A1 (fr) * 2020-04-22 2021-10-28 Exxonmobil Chemical Patents Inc. Films de polyéthylène soufflés résistants à la déchirure

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WO2021216280A1 (fr) * 2020-04-22 2021-10-28 Exxonmobil Chemical Patents Inc. Films de polyéthylène soufflés résistants à la déchirure

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