WO1997022470A1 - Films de polyethylene a orientation biaxiale - Google Patents

Films de polyethylene a orientation biaxiale Download PDF

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Publication number
WO1997022470A1
WO1997022470A1 PCT/US1996/020180 US9620180W WO9722470A1 WO 1997022470 A1 WO1997022470 A1 WO 1997022470A1 US 9620180 W US9620180 W US 9620180W WO 9722470 A1 WO9722470 A1 WO 9722470A1
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WO
WIPO (PCT)
Prior art keywords
film
films
ethylene
density
polymer
Prior art date
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PCT/US1996/020180
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English (en)
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WO1997022470A9 (fr
Inventor
Patrick Brant
James H. Brackeen
Barry Collin Trudell
James I. Ririe
Monty K. Bates
David C. Fischer
Original Assignee
Exxon Chemical Patents Inc.
Empire Films Development Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Exxon Chemical Patents Inc., Empire Films Development Company filed Critical Exxon Chemical Patents Inc.
Priority to EP96944865A priority Critical patent/EP0876250A4/fr
Priority to AU13369/97A priority patent/AU1336997A/en
Priority to KR1019980704592A priority patent/KR20000064446A/ko
Priority to JP52297797A priority patent/JP2002515923A/ja
Priority to HU0001641A priority patent/HUP0001641A1/hu
Priority to BR9612068-1A priority patent/BR9612068A/pt
Priority to NZ326083A priority patent/NZ326083A/xx
Priority to IL12459096A priority patent/IL124590A0/xx
Publication of WO1997022470A1 publication Critical patent/WO1997022470A1/fr
Publication of WO1997022470A9 publication Critical patent/WO1997022470A9/fr
Priority to NO982786A priority patent/NO982786L/no

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene

Definitions

  • This invention relates to a biaxially oriented film of an ethylene based polymer. More specifically, this invention relates to a film layer made from thermoplastic ethylene based homopolymer or random copolymer produced by a metallocene catalyst system, wherein the film layer is stretched in two directions for biaxial orientation
  • Polymeric films are widely used, both in industrial manufacturing processes and in the non-industrial sector for the wholesale and retail delivery of goods to the consumer market.
  • the greatest quantity of polymeric film, in film and bag form, is designed for, use and consumed by the non-industrial sector
  • films composed of ethylene based thermpolastic polymers dominate certain of these consumer market applications ⁇ such as the market for household disposables, trash bags and liners; overwrap films and bags for laundry and dry cleaning goods, and shipping and carryout bags for retail merchandising of non-perishable goods
  • ethylene based polymer films only weakly compete, if at all, with other more expensive polymer films such as plasticized polyvinylchloride films and/or polypropylene films ⁇ such as in the heat-shrink wrap film market for the taut-contour fit wrapping of various items, particularly perishables such as cuts of meat, poultry, and fish
  • ethylene based polymer films compete somewhat in certain circumstances of these applications
  • ethylene based polymer films are essentially uncompetitive with shrink-
  • Heat shrinkable films and packages thereof have gained substantial acceptance for wholesale and retail packaging of food products and goods
  • packing films used to package food products and non-food products must be of high optical clarity (i.e , highly transparent and of low haze and, preferably high gloss) to provide an aesthetically pleasing product and must be sufficiently strong and resilient to provide the necessary protection from normal handling
  • the film must also possess proper barrier properties with respect to permeation by water vapor, oxygen, and/or carbon dioxide.
  • PVC Polyvinyl chloride
  • PVC films are commonly used as an overwrap for trayed cuts of meat and other food products in a retail environment such as a supermarket.
  • PVC is desirable for production of films for this service because it has excellent optics or clarity, good elasticity and strength properties at use temperatures, and satisfactory elastic memory ability and elongation.
  • PVC resins have several disadvantages.
  • PVC film has a poor resistance to physical abuse, and thus, a PVC-based film package sometimes becomes leaky during shipment.
  • PVC film tends to tear along the edges of a sealed overwrap tray, for instance, if rubbed during transit by another tray or an enclosing carton.
  • plasticized films thereof are generally not "heat shrinkable,” which means that after stretching the film while heated followed by cooling, under a later reheating an unplasticized PVC film tends not to return to its original unstretched dimension. If plasticized to enable the production of a heat shrinkable film, then significant concern has to be given to the nature ofthe plasticizer used, its quantity and compatibility with the PVC resin and migration of such plasticizer from a film thereof and its suitability for contact with foodstuffs.
  • the packaging industry desires a film having the advantages of PVC, but without the disadvantages described above.
  • the film should be of high clarity, tear resistant, puncture resistant, and the film should exhibit resistance to deformation or good recovery from deformation and satisfy food law requirements.
  • a vinylidene chloride-vinyl chloride copolymer oriented film does not respond well to later applications of heat Heat causes instantaneous film shrinkage because orientation is lost, heat seals with such films are not smooth, resulting in a weak seal Furthermore, hot melt coatings of this oriented film with another polymeric material to produce a film composite or multilayer film having more desirable characteristics is not possible The oriented film loses its orientation upon contact with a hot melt In lamination, the hot press rolls usually cause the oriented film to react similarly
  • polyethylene (PE) resins employed as such or as a blend component in packaging are high density (HDPE), linear low density (LLDPE), low density (LDPE) , very low density (VLDPE) or ultra low density (ULDPE).
  • LLDPE, VLDPE and ULDPE are ethylene copolymer wherein, typically, the comonomer is a C 3 -C 20 alpha-olefin The comonomer introduces branching into the polymer and affects its density.
  • polyethylenes have been and still are typically made with traditional Ziegler-type catalysts which contain different types of reaction sites resulting in a polyethylene resin containing a broad range of molecules
  • polyethylene resin typically contains polymers having a medium molecular weight with medium branching fraction, a low molecular weight and high branching fraction, and high molecular weight with low branching fraction. This results in inconsistent properties, and sometimes, poor clarity when such resins are converted into films as well as certain difficulties in production ofthe film itself.
  • oriented polymeric films are of multiple layer construction and comprised of at least one barrier or oxygen layer, such as ethylene polyvinyl alcohol (EVOH) or vinylidene chloride-vinyl chloride copolymer, and a of different polyethylenes or of polyethylene layer such as LLDPE, HDPE, LDPE, VLDPE, or blends of polyethylene with acetates, such as ethylene-vinyl- acetate (EVA).
  • EVAs having greater than about 85 wt % ethylene provide substantial structural strength to a film during the second bubble orientation process, and are especially beneficial for the orientation of tubular films.
  • Such multiple layer films are formed by a number of ways, including coextrusion, lamination and coating techniques.
  • a heat shrinkable film should be susceptible to orientation without distortion or separation of the multiple layers which are typically present in films of this nature.
  • the film layer must be strong enough, at the orientation temperature, to withstand the stretching in either ofthe machine direction (MD) or transverse direction (TD) without the creation of holes, tears, or non-uniform zones of stretching.
  • MD machine direction
  • TD transverse direction
  • the film layer must be capable of supporting the stretching bubble during the orientation process.
  • each layer of the film should be susceptible to orientation without fracture, separation, or creation of holes in the layer.
  • the final film product should respond to heat rapidly enough for commercial practicality, and yet must not exhibit such a level of shrink energy as would cause the multiple layer film to pull apart or de-laminate during shrinkage under its own internal forces.
  • oriented films used for shrink packaging should be clear enough for a consumer to visually inspect the packaged item prior to purchasing. If the packaging is cloudy (hazy) or not sufficiently transparent or translucent, a wrapped food item will appear to be undesirable to the consumer. Thus, clarity is a product attribute widely sought in many types of polymer films for certain application.
  • thermoplastic ethylene based polymers have not been adopted by the industry for applications that require softness, but with good shape retention or recovery (snapback).
  • Polyethylene films particularly those of a LDPE or LLDPE, have traditionally been relatively soft or limp, having a low secant modulus, and softness is a desirable property in some applications, such as for wrapping a meat product This would appear to make polyethylene resins desirable for production of films for such services, which due to its lower density and cost, would desirably dispiace PVC films from these services
  • polyethylenes have been largely unsuccessful in replacing PVC in at least the meat wrap application, primarily because a polyethylene film retains or recovers its shape poorly after handling, leaving unacceptable finge ⁇ rints on the film PVC films, on the other hand, snaps back or recovers its shape a few minutes after handling, providing a fresh appearance
  • a film should feel stiff to protect and/or convey the crisp and crunchy nature ofthe product
  • the softness of an ethylene based polymer film has rendered it undesirable for this service
  • the film widely employed for snack food packaging is biaxially oriented polypropylene (BOPP) film due to its high degree of stiffness, its good optical properties of low haze and high gloss, and good barrier properties to water vapor transmission
  • a modified atmosphere package is one wherein the film material of its construction has breathing characteristics within specifically intended ranges relative to the transmissibility of the film to oxygen, carbon dioxide and water vapor
  • MAP modified atmosphere package
  • the transmissibility of a film to these vapors must neither be too low nor too high but should instead correspond ot the "respiration" of the produce product for these vapors.
  • a film for MAP applications should have an oxygen transmission rate (OTR) of about 300-1200 cc mil/100 in 2 atm/day, a carbon dioxide transmission rate (CO ⁇ TR) of about 1,000 to 5,000 cc mil/100 in 2 atm/day and, to prevent dry rot of produce, a water vapor transmission rate (WVTR) of less than 2.5 g mil/100 in 2 day
  • OTR oxygen transmission rate
  • CO ⁇ TR carbon dioxide transmission rate
  • WVTR water vapor transmission rate
  • ethylene based polymer is generally a lower cost product, it has long been seen as a desirable goal to use a thermoplastic polyethylene for various uses that have been heretofore dominated by higher cost polymers.
  • ethylene-based polymers heretofore available have lacked various properties required for a particular film service or were otherwise objectionable.
  • polyethylene was considered too soft and lacking in stiffness
  • a shrink wrap film it has heretofore been necessary to form such films from the heretofore available polyethylene resins by a blown bubble extrusion process and then orient it by a double bubble procedure
  • Formation of a biaxially oriented film of polyethylene by a slot-die casting tenter frame stretching process in which the degree of orientation may be more varied and precisely controlled has not been practical due to the tackiness and inadequate melt strength and excessive melt elasticity of a film layer of an ethylene polymer at the conditions required for tenter frame stretching
  • Cast and blown bubble films prepared from the same ethylene polymer resin and to the same gauge differ dramatically with respect to their haze and gloss properties
  • Cast films have significantly lower haze and significantly higher gloss than do blown bubble films of the same ethylene polymer resin
  • cast or blown bubble films as the density of the ethylene polymer resin of which the film is formed increases the haze of the film increases while its gloss decreases, with the rate of increase/decrease of haze/gloss with increasing resin dinsity being significantly greater for blown bubble than for cast films
  • low haze/high gloss properties may be obtained in a cast film of a low density (d ⁇ 0 940 g/cm 3 ) ethylene polymer (LDPE or LLDPE), but such LDPE or LLDPE films are attended with a lower set of physical strength properties (tensile, elongation, tear resistance) than could be attained with a high density (d ⁇ 0 940 g/cm 1 ) ethylene polymer (HDPE) Even then, such good optics cannot be attained with such low density ethylene polymers in a blown bubble film
  • a high density ethylene polymer can be employed for the cast or blown bubble extrusion of a film to attain the requisite film strength properties but at a sacrifice ofthe film optics, with this sacrifice being much greater for blown bubble films
  • ethylene based polymer films that have been proposed as biaxially oriented heat shrinkable films are those prepared from a blend of a low density ethylene polymer of density from about 0 91 to 0 93 g/cm 3 and a high density ethylene polymer of density from about 0 940 to 0.98 g/cm 3, as described for example in GB 937,807 and GB 1,279,714, or a low density ethylene polymer and a very low density ethylene polymer of density from about 0 87 to 0 910 g/cm 3 , as described for example in EP 0299750 and U S Patent 4,801,652 Even then such ethylene based polymer blend films have not been widely adopted for certain services such as food packaging because of certain real or perceived deficiencies in their properties and/or difficulties in their production
  • a polyethylene ethylene homopolymer and/or ethylene copolymer
  • a film produced from any polyethylene should have good impact and puncture resistance, increased tensile at yield and other physical properties, and low levels of extractables so as to not impart unpleasant odors or tastes to a food product
  • Proper shrink properties are also desired for certain applications such as packaging certain food products and goods, covering windows, and wrapping meat pallets.
  • a film should have as few layers as possible, but with a desirable combination of properties
  • a one-, two- or three- layer film structure that may be produced from a thermoplastic ethylene based polymer resin that has good clarity, high strength, and which can be readily heat sealed with a strong seal resulting and printed upon with protection for the printing, which may be biaxially oriented to yield a heat shrinkable film.
  • ethylene based polymers produced from a catalyst having essentially only one type of catalytic site may be fabricated into oriented films having improved properties with respect to heat sealability, greater impact strength, puncture resistance, and optimal optic properties such as haze and gloss
  • an ethylene based thermoplastic polymer produced with a metallocene catalyst may be fabricated into a film which can meet the needs of the food packaging industry, the pallet shrink-wrap industry, and the market for individual shrink wrapped goods
  • This invention comprises a film layer formed by cast or blown bubble extrusion of a single ethylene polymer resin which is then biaxially oriented by a tenter frame or double bubble procedure to yield a biaxially o ⁇ ented film layer that has good optical properties of low haze and high gloss — like that of a cast extrusion LDPE film — while exhibiting high strength properties — like that of a cast or blown bubble extrusion HDPE film
  • extruded articles such as film, or other fabricated articles made from such film, are comprised of an ethylene homopolymer or a copolymer of ethylene and at least one C 3 -C 20 alpha-olefin
  • the alpha-olefin of the copolymer is present in the range of from about 0 01 to about 6 0 mole percent of the copolymer, for C 4 -C 20 alpha-olefins preferably no greater than 5.0 mole %
  • the ethylene based polymer will have a content of ethylene greater than 90 wt%, a ratio of weight average molecular weight (M,,) to number average molecular weight (MJ of M ⁇ /M,, ⁇ 3, a ratio of a Z - average molecular weight (MJ to weight average molecular weight of M M w ⁇ 2, a composition breadth distribution index (CDBI) of 50% or preferably greater, such as 55 %, a density in the range of from about
  • CDBI
  • Biaxially oriented film made from such ethylene based polymers will exhibit certain film properties that are relatively sensitive to a change of polymer density, such as
  • WVTR Water Vapor Transmission Rate
  • a film may be engineered to provide a target or desired property value relating to film strength, vapor barrier properties and the like by appropriately controlling the conditions and degree of orientation imparted to it in the MD and TD
  • a biaxially oriented film comprised of such ethylene based polymers will exhibit properties such as' a) haze in the range of from 0 to 5%; b) gloss above about 65%, c) dart drop impact above 400 g/mil at a resin density of 0.917 g/cm 3 and no lower than 150 at a resin density of 0.940 g/cm 3 ; d) oxygen transmission rate below about 600 cc-mil 100 in 2 -atm/24 hours @ 25°C: e) a tensile at yield of 2000 psi or greater (MD) or 5000 psi or greater (TD); f) a secant modulus (1%) above about 40,000 psi (MD), or above about 70,000 psi (TD) and, g) shrinkage of at least 10% in each ofthe oriented directions.
  • properties such as' a) haze in the range of from 0 to 5%; b) gloss above about 65%, c) dar
  • Shrink films made form such ethylene homopolymers and ethylene-alpha-olefin copolymers and articles made from these films will be particularly useful in applications where maximizing optical properties, secant modulus, impact resistance, puncture resistance and the like are important.
  • one preferred embodiment ofthe present invention provides an ethylene based polymer film having an oxygen permeability no greater than about 500 and typically about 150-450 cc/100 in 2 /24hr.
  • the film comprises a biaxially oriented (BO) film having increased optical clarity, puncture resistance and tensile strength, said film comprising at least one layer of an ethylene copolymer thermoplastic resin produced from a metallocene catalyst and having an ethylene content of greater than 90 wt%, a density range from 0 915 g/cm 3 to about 0.930 g/cm 3 .
  • the film layer is biaxially orientable to an extent of 5 x 8 or 7 x 7 (MD x TD).
  • the biaxially oriented film (BOF) is heat shrinkable and more preferably exhibits a 76% shrink in the machine direction.
  • the film is 100% recyclable
  • Another preferred embodiment of the present invention also provides a biaxially oriented (BO) film comprising at least one layer of linear low density ethylene-alpha-olefin copolymer density of 0.915 to 0.940 g/cm 3 polymerized with a metallocene catalyst, which may hereafter be referred to as a "m-LLDPE" resin.
  • the m-LLDPE film has improved optical clarity and physical toughness for biaxial orientation, and optionally may comprise a second and third layer.
  • the BO-m-LLDPE-film includes a first layer and a second layer that are co ⁇ extruded.
  • the BO-m-LLDPE-film can also include a fourth layer adhesively laminated to the third layer.
  • the present invention also comprehends packages fabricated from the films ofthe invention wherein the second or third layer is heat sealed
  • the invention further includes a method for packaging a product such as a compact disc or software package and shrink wrapping the product in a package made from the BO-m-LLPDE-film ofthe present invention
  • the invention comprehends a method for wrapping an item, preferably a window frame or door frame comprised ofthe film ofthe present invention
  • a radar plot or diagram is a multiple axis (> 3) graphs wherein each radiating axis from the center point of its origin to its end point represents a range of values ⁇ either actual or as a percentage of an assigned maximum value (relative) ⁇ with each axis representing the value range of a different chemical/mechanical/physical property of the final film product or the film resin, as may be indicated on the plot
  • ⁇ either actual or as a percentage of an assigned maximum value (relative) ⁇
  • each axis representing the value range of a different chemical/mechanical/physical property of the final film product or the film resin
  • Fig 1 is a radar plot by which the final film properties of an m-E-polymer BO film of 1.62 mil thickness and 5 x 8 orientation of this invention is compared on a relative basis to a blown but unoriented m-E-polymer film prepared from the same resin, namely EXCEED 350 D60
  • Fig 2 is a radar plot by which the final film properties of an m-E-polymer (EXCEED 350 D60) BO film of 1 62 mil thickness and 5 x 8 orientation of this invention is compared on a relative basis to a commercially available film of biaxially oriented polypropylene (BICOR* , from Mobil Chemical Co )
  • Fig 3 is a radar plot by which on a relative basis the final film properties of an m-E-polymer (EXCEED 301) BO film of 5 x 5 o ⁇ entation of this invention is compared to a blown film of a high density polyethylene
  • Fig 4 is a radar plot by which on a relative basis the final film properties of three BO films of EXCEED resins of different densities (0 917, 0 922; 0.926-g/cm 3 ) are compared; the 0.917 g cm 3 density resin BO film (350 D60) being of 5 x 8 BO and 1 62 mil gauge and the other films being of 6 x 6 BO and 0.6 mil gauge
  • the present invention comprises the utilization of ethylene based polymers having certain minimum characteristics with respect to their ethylene content; molecular weight, both M ⁇ , and Mlois; their density, and the compositional uniformity of the ethylene based polymer resin: for the production of a film layer which upon biaxial o ⁇ entation yields a film article having a set of physical/mechanical/chemical properties requisite to the service required of such film for various particular applications which heretofore have not been particularly serviceable by an ethylene based polymer film.
  • the present invention concerns certain classes of biaxially oriented films fabricated from ethylene based polymers made utilizing a metallocene catalyst system, articles made from these films, and uses of the films and/or articles.
  • ethylene based polymers include ethylene homopolymers and ethylene copolymers in which ethylene is the predominate monomeric constituent by weight or mole %; specifically, ethylene comprises at least and preferably more than 90 wt % of the ethylene based polymer while the comonomer content thereof does not exceed 6 0 mole % of the ethylene based polymer and the CDBI of the polymer exceeds 50%.
  • such ethylene based polymers comprise at least about 93 wt % ethylene monomeric units and the comonomer content thereof does not exceed 5.0 mole % and more preferably the comonomer content does not exceed about 3.3 mole % of the ethylene based polymer
  • Such ethylene based polymers may hereafter be referred to generally as an "m- polyethylene” or as an “m-E-polymer "
  • oriented means that the m-E-polymer film has been stretched while in a softened state while at a temperature below that at which the film layer was initially extruded by a cast or blown bubble technique
  • biaxially means that the cast or blown bubble m-E-polymer film has been stretched in both of a machine direction (MD) and a direction transverse to the machine direction (TD), as described further below
  • MD machine direction
  • TD transverse to the machine direction
  • the degree of biaxial orientation is denoted as the percentage as compared to the original dimensions ofthe extrusion formed film layer that the film layer is stretched, i e , such as 100,200 600 % of its original dimension of length (MD) or width (TD).
  • lxl orientation means that the initial film layer has been stretched to twice its original dimension in each of the machine direction (MD-length) and transverse direction (TD- width); 6x6 would denote a stretching to six times the original length and width dimensions ofthe initially formed film layer.
  • Films produced of the particular ethylene based polymer in their biaxially oriented form have unique characteristics, which may be manipulated by the degree of or type of orientation, which make them well suited for use in certain service applications.
  • ethylene copolymer as used herein shall mean copolymers of ethylene and alpha- olefins. Such alpha-olefins will generally have 3 to 20 carbon atoms. Polymers of ethylene and one or more or these alpha-olefins are contemplated. Preferred alpha-olefins are butene-1, pentene-1, 4-methyl-l-pentene, hexene-1, octene-1 and decene-1.
  • the present invention provides an m-E-polymer film layer that is biaxially orientable without difficulty by either o the double bubble or tenter frame processes to yield an oriented film having superior optical properties, outstanding dart drop impact resistance and puncture resistance, and a dramatically increased secant modulus.
  • a biaxially oriented m-E-polymer film according to the present invention is a stiffer film than previously available polyethylene films, has improved clarity, and is better able to withstand the rigors that a film encounters in service.
  • the present invention provides various articles of manufacture, typically for packaging, and methods for making these articles.
  • Articles contemplated by the present invention include a shrink wrap pallet film, a film for wrapping goods, packages for goods such as snacks, including potato chips and dry cereals; shrink wrap films for meats and poultry; and typical film applications such as diaper backsheets
  • the required stiffness may be engineered into the final film product, ranging from relatively soft to relatively stiff, by control ofthe degree of orientation imparted to the film in one or the other, or both, of the MD and TD.
  • the present invention provides BO-m-E- polymer films for shrink wrapping individually packaged items, with applications ranging from packaging compact discs to providing poultry bags
  • Some ofthe BO-m-E-polymer films embodying this invention are serviceable as heat shrinkable packages in which a product is inserted, air is normally evacuated, the open end of the bag is closed, such as by heat sealing, and heat is applied to shrink the film for a tight and conforming fit around the product.
  • films may be intended for service as a general heat shrink wrap for non-perishable good or for perishable food goods such as meats, or the like.
  • the intended service wili then require as final properties ofthe film certain minimum properties with respect to (1 ) haze and gloss, depending upon whether user viewability ofthe packaged goods are or are not of a practical concern; (2) oxygen and moisture barrier moderating properties, a particular concern with respect to food packaging; (3) secant modulus (flexibility - resistance to deformation), to be geared to the preference ofthe end user market, (4) degree of shrinkability, to be geared to the preference of the end user market; (5) puncture resistance, tensile impact, tear strengths and elongation properties of suitable minimums for service.
  • the requisite minimum service properties required ofthe film for use in a particular application is then imparted to the film by proper selection ofthe film base m-E-polymer resin and the selection ofthe film forming and orientation conditions.
  • Catalyst for polymerization of the ethylene based polymers here concerned are comprised of a transition metal component having at least one organo ligand which contains a cyclopentadienyl anion moiety through which the organo ligand bondingly coordinates to the transition metal cation.
  • Such catalyst systems are now commonly referred to as “metallocene” ( ) catalysts and many examples of such metallocene catalyst systems have now been described in the art.
  • ZN catalysts are essentially single cited catalysts whereas ZN catalysts are multi-sited catalysts that generally produce a polymer resin having a great diversity of polymeric species.
  • an ethylene-alpha-olefin copolymer produced by a metallocene catalyst is generally much more uniform with respect to the polymeric species that comprise the resulting m-E-polymer resin, particularly with respect to the disparity between the differing molecular weight fractions thereof ⁇ as indicated by the M M,, value ofthe m-E-polymer resins generally being ⁇ 3.0 -- and with respect to the distribution of alpha-olefin comonomer between the different molecular weight fraction thereof — as indicated by a high comonomer distribution breadth index (CDBI) value of 50% and higher.
  • CDBI comonomer distribution breadth index
  • the ethylene based polymers utilized in the present invention are preferably produced using supported or unsupported metallocene catalysts
  • the polymers may be produced in many types of reactors or reaction schemes, including, but not limited to, fluidized bed or stirred bed gas phase reactors, slurry or bulk liquid reactors of tank or loop type, solution, or any other process practiced for the poly e ⁇ zation or copolyme ⁇ zation of ethylene
  • a catalyst system comprising bis(l,3 methyl-n-butyl cyclopentad ⁇ enyl)zircon ⁇ um dichlo ⁇ de activated with methyl alumoxane (MAO) is the catalyst of choice
  • MAO methyl alumoxane
  • the ethylene polymers of the present invention will generally have a narrow molecular weight distribution (MWD), as characte ⁇ zed by the ratio of weight average molecular weight (M Thread) to number average molecular number (MJ, H M,, These M Springfield, and M n values are determined by Gel Permeation Chromatography (GPC)
  • MWD for the m-E-polymers ofthe present invention is less than or equal to 5, preferably ⁇ 3 5, more preferably ⁇ 3 0, and most preferred ⁇ 2.5
  • Embodiments of these m-E-polymers will have a density in the range of from about 0 915-0.965, preferably 0 917-0 95, more preferably 0 917-0 940 and most preferably from 0 920 to 0 94 g/cc
  • Resins produced by the above referenced processes and catalysts will be homopolymers or copolymers that contain greater than 90 wt % ethylene, preferably 93 wt % ethylene or greater, and may inco ⁇ orate one or more alpha-olefins comonomers in the range of from about 0 01 mole percent to about 6 0 mole %, preferably 5 0 mole % of less, and most preferably no more than about 3 3 mole % comonomer In a preferred embodiment, the comonomer ranges from about 0 1 to about 3 mole percent
  • Copolymers produced from a catalyst system having a single metallocene component have a very narrow composition distribution - most ofthe polymer molecules will have roughly the same or comparable comonomer mole % content Ziegler-Natta catalysts, on the other hand generally yield copolymers having considerably broader composition distribution meaning that comonomer inclusion vanes widely among the polymer molecules
  • composition distribution Breadth Index As defined in U S Patent 5,382,630 which is hereby inco ⁇ orated by reference CDBI is defined as the weight percent ofthe copolymer molecules having a comonomer content within 50% of the median total molar comonomer content
  • CDBI Composition Distribution Breadth Index
  • the CDBI of a copolymer is readily determined utilizing will known techniques for isolating individual fractions of a sample ofthe copolymer One such technique is Temperature Rising Elution Fraction (TREF), as described in Wild, et al., J Poly Sci . Polv Phvs Ed . vol 20, p 441 (1982) and U S Patent No 5,008,204, which are inco ⁇ orated herein by reference
  • TREF Temperature Rising Elution Fraction
  • a solubility distribution curve is first generated for the copolymer This may be accomplished using data acquired from the TREF technique described above
  • This solubility distribution curve is a plot of the weight fraction of the copolymer that is solubilized as a function of temperature This is converted to a weight fraction versus composition distribution curve
  • Mn is the number average molecular weight ofthe fraction
  • Low weight fractions generally represent a trivial portion of the polymer The remainder of this description and the appended claims maintain this convention of assuming all fractions have Mn ⁇ 15,000 in the CDBI measurement
  • the CDBI is determined by establishing what weight percent ofthe sample has a comonomer content within 25 % of each side of the median comonomer content Further details of determining the CDBI of a copolymer are known to those skilled in the art See, for example, PCT Patent Application WO 93/03093, published February 18, 1993
  • the m-E-polymers employed in the films of this invention have CDBI's equal to or greater than 50% the range of 50-98%, usually in the range of 50-70% and most typically in the range of 55-60%
  • m-E-polymer resins have a melt index (MI) in the range of from about 0 5 to about 10, preferably in the range of from about 1 0 to 5 0, and more preferably from 1 to 4 0 dg/min
  • MI melt index
  • the MI range for film production of an m-E-polymer via a blown tube technique is preferably from about 0 8 to about 2 0, for cast film production the MI range ofthe m-E-polymer is preferably from about 0.75 to 4 0, preferably 1 to 5 0, more preferably 1 to 4.
  • Choice of melt index for the m-E-polymer will generally be driven by the type of extrusion process and the specific equipment in use as well as the end use for films and/or subsequent use in converting operations
  • the maximum extractables level of the products ofthe present invention is expected to be less than about 5 wt%, preferably less than about 4 wt%, and most preferably less than about 3 wt%
  • the m-E-polymers used in this invention have an I 21 I 2 or melt index ratio (MIR) less than 35, generally in the range of from about 16 to 22 DRI ranges from about 0 to 0 4, preferably from about 0 to 0 25, more preferably from 0 to 0 2, and most preferably from about 0 to 0.15
  • DRI melt index ratio
  • the EXCEEDTM m-E-polymer resin product now available from Exxon Chemical Company is a metallocene catalyst produced ethylene based copolymer
  • the processing of an EXCEEDTM resin may be performed in a manner which is similar to that of conventional LLDPE with minimal equipment conversion required
  • a thermoplastic film made from an EXCEEDTM resin has demonstrated a 50 percent increase in puncture resistance and a 40 percent increase in tensile strength, as compared to a conventional polyethylene film
  • EXCEEDTM is a copolymer of ethylene and hexene-1 and is a linear polymer and a unique type of linear low density polyethylene
  • This metallocene produced m-E-polymer has a narrow molecular weight distnbution (M ⁇ /MJ, typically less than 3 0 while having useful weight average molecular weights (Mw) of greater than 10,000 and less than 500,000, and a narrow range of short chain branching (SCB) of about 12 and less than 30 SCB/1000 carbon atoms
  • the EXCEEDTM class of polyethylenes (wherein the comonomer is a C 4 -C 8 alpha-olefin) have a substantial absence of low molecular weight and high comonomer content molecules, a substantial absence of high molecular weight and low comonomer content molecules, as indicated by CDBI ⁇ 50 %, a narrow molecular weight distribution, and slightly lower melt strength than traditional linear ethylene polymers, and a slightly flatter
  • Blown films produced with an annular die and air cooling and cast films using a slot die and a chill-roll for cooling are both acceptable techniques for making a film layer of the m-E-polymer resin according to the present invention Any technique may be used, provided the resulting film meets the specifications stated herein
  • additives including pigments, plasticizers (?), tackifiers, anti-static agents, anti-fogging agents, antioxidants or other additives are also contemplated and may be included in the resins and/or films made therefrom
  • Multilayered structures may be preferred in some applications
  • Such structures include, but are not limited to, coextruded films, and laminated films
  • Laminated films can include not only one or more film layers based on m-E-polymers o the present invention, but other film layers as well, including but not limited to, polyester, polyamide, polypropylene, other polyethylenes, Saran®, ethylene v yl alcohol, and the like
  • Methods of lamination include extrusion lamination, adhesive lamination, heat lamination, and the like
  • Other materials may be laminated to final films structures of this mveniton, including films based on embodiments ofthe present invention, for instance paper, aluminum foil, paperboard, woven and non-woven materials
  • films where one or more layers are at least partially cross-linked by radiation Such radiation and the techniques to achieve it are well known to those of ordinary skill in the art These techniques include both gamma (cobalt 57) and x-ray radiation, electron beam and ultraviolet
  • the film ofthe present invention can be any suitable thickness, depending upon the end use for the film. Typical thicknesses may range from about 3 microns to about 0.030 inches (0.25 mm) for a thin film to about 1 to 2 mm if a thick film is desired.
  • the film can be obtained in a rollstock format for automatic form, fill and seal equipment or as preformed bags or pouches.
  • the metallocene produced polyethylene films of this invention can be heat-shrinkable, that is an oriented m-E-polymer film can return to its original unstretched size when heated to its softening point.
  • the terms "orientation” and "oriented” describe a manufacture of metallocene m-E- polymer heat shrinkable films.
  • the m-E-polymer resin is heated to its flow or melting point and extruded through a die into either tubular (blown bubble) or sheet (cast) form and then cooled from its extrusion temperature. After cooling, the relatively thick extrudate is, as necessary, reheated to a temperature range suitable to orient or align the crystallites and/or molecules of the base m-E- polymer resin.
  • the orientation temperature range is a range of temperatures in which the intermolecular configuration of the resin is revised by physical alignment of the crystallites and/or molecules of the resin to improve certain mechanical properties ofthe film, such as shrink tension as, for example, measured in accordance with ASTM D-2838-81.
  • m-E-polymer extrudate film layer While the m-E-polymer extrudate film layer is within the orientation temperature range, it is stretched, which changes intermolecular configuration, and then cooled while in the stretched or extended position. Cooling of the film stock while in the stretched position locks the crystallites and/or molecules of the material into a desirable configuration, providing an oriented film. Upon subsequent reheating to its softening point, as may occur during a packaging operation, forces within the film cause it to shrink essentially back to its original unstretched position. In this manner an oriented film is heat shrinkable, providing a shrink wrap film.
  • uniaxial or monoaxial orientation results.
  • biaxial orientation results.
  • uniaxial orientation is typically provided by running a downstream roller at higher revolutions per minute than an immediately upstream roller, thereby stretching the film. This orients the film layer along its length in the machine direction (MD).
  • MD machine direction
  • Biaxial orientation is provided by also stretching the film layer along an axis at an angle to the uniaxial axis.
  • biaxial orientation is provided by stretching in the machine direction and in a transverse direction (TD) at a right angle to the machine direction which is along the width of the film layer
  • Transverse stretching can be provided by a machine called a TM Long or by a machine called a tenter frame stretcher
  • a monoaxially o ⁇ ented film typically refers to films oriented primarily in the longitudinal direction However, some incidental orientation can be present in the transverse direction
  • the term can also refer to films o ⁇ ented principally in the transverse direction, such as can be provided in a blown tubular film, with or without some incidental orientation in the longitudinal direction
  • a biaxially oriented film (BOF) for pu ⁇ oses of this application means a film the film layer of which, after its initial formation, is then intentionally and specifically oriented in the longitudinal direction (MD) and transverse direction (TD) by a degree that is beyond that which may be imparted a mere blown bubble process of forming the initial film layer itself, with the longitudinal direction being in the direction of the machine and transverse direction is the direction transverse to the machine
  • the biaxial stretching of the m-E-polymer film of the present invention can be carried out simultaneously or successively, with successive biaxial stretching being preferred, in which stretching is first carried out longitudinally then transversely
  • Oriented m-E-polymer films may be produced by either post extruder manipulation of a blown film through heating and onentation (often called “double bubble” or “trapped bubble”), or by longitudinal stretching of an extruded sheet followed by tentering techniques Orienting the film by a tentering technique is preferred since this generally produced a biaxially oriented film of superior mechanical/physical properties compared to orientation by a double bubble technique
  • Films after onentation are generally in the range of from about 0 2 to about 10 mils (5 08 to 254 ⁇ m) thick (gauge), preferably from 0 5 to 5 mils, and most preferably from 0 6 to 3 mils
  • Films layers formed by cast or blown bubble techniques to be produced into oriented structures will generally necessarily be thicker prior to orientation and will range from about 4 to about 25 mils Choice of the thickness (gauge) prior to orientation will depend on orientation equipment, degree of intended o ⁇ entation, and the properties intended of the film and/or resin All such parameters are well within the
  • biaxial orientation will include orientations such as 2x2, 3x5, 5x5, 6x6, 7x7, 5x8 and the like These notations will indicate a combination of film stretching in both the machine direction (MD) and transverse direction (TD) where 2 or 3, for instance indicate 200 or 300 percent difference in dimension after orientation The amount of orientation need not be equal in both directions Film Properties
  • oriented m-E-polymer films made according to the present invention will generally be clearer, stiffer, stronger and exhibit greater shrinkage when heated These stiffer, clearer and stronger BO-m-E-polymer-films may be used to make packages for crisp snacks, fresh meat, fresh produce, consumer soft and hard goods and the like.
  • Films made from the polymers of certain versions of the present invention may be used to contain food articles such as meats and snacks for instance.
  • Such m-E-polymer so be used to protect and display articles of apparel and other consumer goods such as computer software, books, compact discs and a wide variety of magnetic storage media
  • Peak Puncture Strength greater than 40 lbs, preferably greater than 45 lbs/mil, more preferably above about 50 lbs/mil; Puncture Break Energy greater than about 25, preferably greater than 30 in-lb/mil;
  • E-polymer films will be relatively soft, but strong and with excellent clarity. These lower density BO m-E-polymer films will compete favorably with plasticized PVC films in applications such as meat wrap. On the other end of the spectrum, at higher densities, e.g. 0.920 - 0.960, preferably 0.925 to 0.950 g/cm 3 , BO m-E-polymer films fabricated from these ethylene polymers will have a high modulus and be very stiff and have excellent clarity. These BO higher density m-E-polymer films will compete favorably with biaxially oriented polypropylene in either single or multiple layers in applications such as snack and cereal packaging.
  • the biaxially oriented films ofthe present invention exhibit many improved physical properties as compared to substantially unoriented films such as standard blown or cast films.
  • biaxially oriented m-E-polymer films of this invention have better optical properties, exhibiting excellent clarity.
  • Tensile at yield for these biaxially oriented m-E- polymer films can be expected to be 120-300% (MD) or 150-600% (TD) minimum greater than tensile at yield for a substantially unoriented film.
  • Oriented films based on the ethylene polymers ofthe present invention may find applicability in retail fresh meat packaging. In such packaging the meat is often placed in a tray, frequently made of foamed polystyrene and then typically over-wrapped with a plasticized PVC film. Attempts in the past to utilize polyolefins, more specifically ethylene polymers, have centered around improving the ethylene polymer's recovery to equal or exceed that of PVC. However, oriented m-E-polymer films according to the present invention do not depend upon recovery. Instead, these oriented films are relatively unyielding and thus are unlikely to indent under normal handling.
  • These films are resistant enough to stress to successfully resist indentation, which is exemplified by their high tensile at yield. Although these films are relatively unyielding, the films are still soft enough to allow easy wrapping and thus will compete favorably against plasticized PVC film in these applications.
  • Film ofthe present invention offers improved performance in the shrink-wrap market.
  • the film includes at least one layer comprised of a polymer of ethylene polymerized in with a metallocene catalyst in the presence of a C 3 to C g alpha-olefin comonomer.
  • the layer is selected from an ethylene alpha-olefin copolymer having a density of and above 0.917 g/cm 3 wherein the comonomer is a C 4 -C 8 alpha-olefin.
  • the final film may have multiple layers, and the thickness of the layers may be reduced without changing the product quality.
  • Each layer ofthe shrink wrap fiim is preferably comprised of a resin manufactured using a single-site catalyst, a metallocene.
  • the shrink wrap film is preferably comprised of a metallocene produced linear low density polyethylene (m-LLDPE) resin of density from about 0.917 to about 0.940 g/cm 3 which is cast or blown to a film layer that is then oriented in the MD and TD to produce products such as stretch film, heavy-duty shipping sacks, flexible processed-meat packaging, poultry bags and the like
  • m-LLDPE linear low density polyethylene
  • a preferred use of the BO-m-LLDPE film is shrink wrapping products such as compact discs This improved film exhibits an increase in puncture resistance and an increased tensile strength over the existing films used for shrink wrapping.
  • Additional layers can include, as desired, a barrier or oxygen layer for shrink wrapping food products and pallets of food. If the film structure is more than one layer, the layers can be joined by any suitable means. Co-extrusion is preferred
  • a m-LLDPE is an ethylene-alpha-olefin random copolymer having densities preferably from about 0. 17 to 0.940 g/cm 3 .
  • the alpha-olefin comonomer used in m-LLDPE is usually butene-1, hexene-1 or octene-1 ; however, other comonomers can be used, such as 5-methyl-l -pentene, or any other C 3 -C 8 alpha olefin.
  • Branches of the preferred m-LLDPE are short chain branches, 6 carbons and less, due to the comonomer, and the m-LLDPEs do not have many long branches off the main chain
  • the branching of this resin controls density and crystallinity
  • the preferred density of the metallocene LLDPE used in the film structure of the present invention is 0 917 to 0 924 g/cm 3 .
  • the shrink wrap films of the present invention comprised of such m-LLDPE exhibit improved haze and gloss
  • the metallocene LLDPE biaxially oriented film of the present invention meets the requirements of the shrink wrap industry by having excellent stretch and resistance to deformation and being resistant to abrasion
  • the film of the present invention has good machinability, adequate slip properties and is resistant to burn through.
  • biaxially oriented films made according to the present invention offer superior properties.
  • the biaxially oriented films shrink more, and this property, combined with other desirable properties, makes these BO-m-LLDPE films desirable for the shrink-wrap market.
  • Films of the present invention may also comprises a biaxially-oriented high density polyethylene (HDPE) based on a metallocene or single-site catalyst (m-HDPE).
  • HDPE high density polyethylene
  • m-HDPE metallocene or single-site catalyst
  • the biaxially oriented film of the present invention has at least one layer comprised of m- HDPE that can be used as a replacement for certain applications involving polypropylene or nylon.
  • a m-HDPE film can be used as a barrier layer in multilayer films for packaging or for skin packaging films.
  • the m-HDPE film of the present invention has a high molecular weight and is extrusion blown, and as biaxially oriented it can be used to produce clear shopping bags for use in a retail application.
  • This BO-m-HDPE film can also replace polyethylene-nylon structures for uses as containers for food, medicine and the like.
  • a m-HDPE film can preferably undergo a blown film extrusion process with at least one additional film layer.
  • the resulting film is a thin gauge, single or multilayer m-HDPE film with good heat seal performance, excellent strength and uniform thickness or roll quality.
  • Films according to the present invention are especially useful for packaging individually wrapped items, for instance, musical compact discs, software computer packages, musical tapes, and pallets of bulk items.
  • the invention is not necessarily limited by the product contained within a package made from the inventive film as the film can suitably be used whenever a "wrapping" is desired, such as for winterizing windows from the influx of cold air.
  • inventive film and packages therefrom exhibit excellent clarity and seal strength.
  • inventive film and packages are suitable for the food service industry (e.g., hospitals, schools, restaurants, fast food, etc.) and the shrink wrapping industry (e.g., stretch film used in the retail music business, computer software business, toy business, and the construction business) where appearance and seal strength are especially important and long shelf-life may be required.
  • biaxially oriented m-E-polymer films of the present invention The high clarity, variable stiffness, and the engineerable oxygen (OTR) and water vapor transmission rates (WVTR) make these films highly advantageous in applications such as modified-atmosphere packaging for fresh fruits, vegetables, meats and the like.
  • OTR engineerable oxygen
  • WVTR water vapor transmission rates
  • These biaxially oriented m-E polymer films conform to the contours of products very well as compared to, for instance, oriented polypropylene.
  • these biaxially oriented m-E polymer films are desirable as label stock (pressure sensitive, adhesive and the like).
  • These biaxially oriented m-E polymer films can have a relatively high one-percent secant modulus, which means that these films can be relatively stiff. Further, these films have a relatively low water vapor transfer rate (WVTR), which is good for keeping dry foods dry and moist foods moist.
  • WVTR water vapor transfer rate
  • the stiffness of these BO-m-E polymer films conveys a sense of crispness, making these films desirable for packaging dry snacks such as cookies, crackers, potato chips, corn chips, peanuts, pretzels and the like, while the low WVTR keeps the snacks dry and crisp.
  • these films are well suited for applications including cereal packaging as an inside liner/container, particularly since these films can be heat sealed For such applications either single or multilayer films and/or bags can be used
  • the high percentage shrink and the low oxygen transfer rate (OTR) makes the biaxially oriented m-E-polymer films particularly well suited for shrink-wrap packaging of fresh, cooked, and processed meats, poultry, fish, and the like, as well as other moist foods subject to spoilage
  • These films can be metallized for packaging of foods and for decorative applications, and/or they can be made opaque for packaging, for instance, candy bars On the other hand there are numerous nonpackaging applications for which these films are suitable such as for document or photo protective covers
  • the package formed from the film structure of the present invention can also contain resealing means positioned away from a pe ⁇ pheral heat seal
  • resealing means positioned away from a pe ⁇ pheral heat seal
  • a slot means can be provided on one interior face and tab means on an opposing interior face ofthe package such that after the heat seal is cut away, a consumer can reseal the package by pressing the tab into mating engagement with the slot
  • resealing means or slot and tab means are existing in the art
  • Printing can be applied directly to the film if desired and ink can be imparted to the film by a flexographic or rotogravure apparatus
  • ink employed must be suitable for the application
  • the p ⁇ nting can be placed upon an outer or inner exposed surface or upon an inner surface of a multilayer film
  • a tear line can be provided The film can be laser scored to form a single line or parallel lines of weakness in at least one layer of film ofthe present invention by partially vaporizing the film with a beam of radiant energy
  • the score lines form a tear path in a multilayer film
  • the score line may extend across the entire surface ofthe film
  • MI Melt Index
  • WVT R Water Vapor Transmission Rale
  • ASTM E96 Water Vapor Transmission Rale
  • Exceed® 301 (now EXCEED* 357C32), an ethylene copolymer with hexene-1 manufactured with a metallocene catalyst by Exxon Chemical Co , Baytown, Texas, having a 0 917 g/cm 3 density, a 3 4 melt index and having a peak melting point of 1 15°C (by DSC), was cast into a 15 mil film on a Killion extruder Subsequently, the film was placed in a T M Long film stretch laboratory tenter frame o ⁇ entation device and o ⁇ ented to 5x5, indicating the amount of o ⁇ entation or stretch in the machine direction (MD) and transverse direction (TD), respectively The stretcher was manufactured by T M Long of 405 B ⁇ dge Street, Summerville, NJ 07986 Orientation temperatures used were 235, 245 and 250°F These BO-m-E-ppolymer films, by compa ⁇ son to an unoriented film cast (cast-UO) of the same m-E-polymer (
  • a film sample from EDC 103 (now EXCEED® 350D60) , an ethylene-hexene copolymer of density 0 917 g/cm 3 , 1 0 melt index, 17 2 melt index ratio, CDBI about 58, MWD about 2 3, and peak melting point 1 18°C (by DSC) manufactured by Exxon Chemical Co , Baytown, Texas, was made to a gauge of 1 62 mil and a 5 x 8 biaxial o ⁇ entation
  • Two films ofthe EXCEED 350 D60 resin were also made by a blown bubble process, one to a greater gauge (3 mil) and the other to a lower gauge (0 8) than that of the oriented film and these blown films (blown-UO) were not thereafter onented
  • Fig 1 is a radar plot that compares the final film properties measured for the BO Em-E-polymerfilm and the unoriented blown m-E-polymer film of 0 8 mil gauge
  • a biaxially oriented polypropylene (BOPP) film commercially available as B ⁇ cor®B from Mobil Chemical Co , Beaumont, Texas, and is believed to be based on a homopolymer polypropylene is compared in its properties with respect to a 5 x 8 biaxially oriented film of EDC 103 (or EXCEED 350 D60) at 1 62 mil gauge vs Bicor B® at 1 25 mil in Figure 2
  • MI 1 prepared from a metallocene catalyst
  • the BO EDC 103 film by comparison to the BOPP film, exhibited reduced haze and 1 % secant modulus; comparable tensile strength and WVTR, greater Elmendorf tear strength and OTR.
  • Exceed®301 (now EXCEED 357 C 32) , an ethylene-hexene copolymer of 3 mole % hexene, density 0.917 g/cm 3 , melt index of 3.4 was processed by the procedure of Example 1 into a 5 x 5 biaxially oriented film and its mechanical/physical/chemical properties were determined, including its WVTR.
  • Figure 3 presents a comparison of the properties ofthe respective films wherein between the two film samples the highest value of a film property is assigned as 100%o and the value of that property in the other film is plotted as a percentage of that highest film property value. Accordingly, as shown by Figure 3, the WVTR value of each film is 100%.
  • the biaxially oriented Exceed® 301 film had the greatest dart impact and Elmendorf tear resistance (the HDPE film being of less than 15% of these values) and the least haze (plotted as 1 HAZE).
  • the HDPE film had the greatest secant modulus, with the biaxially oriented Exceed® 301 film having about 35 % of the secant modulus ofthe HDPE film.
  • the comparison establishes that a biaxially oriented m-E-polymer film of this invention would be a ready and desirable replacement film for HDPE films now made for service as cereal box liner films.
  • EXCEED polymers of three differing densities namely EXCEED 350 D60 of density 0.917 g cm 3 , EXCEED 377 X 60 of density 0.922 g/cm 3 and EXCEED 399 X 60 of density 0.926 g/cm 3 ; were produced as biaxially oriented films wherein the EXCEED 350 D60 was 5 x 8 oriented and the other films were 6 x 6 oriented films Radar plot Fig 4 illustrates the relative differences in the properties for these films
  • Table 2 hereafter identifies the resin and film properties respecting all cast, blown and biaxially oriented films that were prepared and reported by these Examples 1-6.

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Abstract

L'invention se rapporte à des articles et à des film obtenus à partir de polymères à base d'éthylène fabriqués au moyen d'un système catalyseur d'alliage organométallique. L'orientation biaxiale améliore spectaculairement la transparence, la rigidité, la résistance au choc au mouton, la résistance au percement, et le rétrécissement. La résistance à la traction et la tension de rupture sont également améliorées. La rigidité du film, telle que mesurée par le module sécant, est augmentée de 300 % sur un film non orienté du même polymère d'éthylène. Ces articles et ces films sont utilisés comme emballages moulants, surenveloppes et dans des applications d'emballage à sec tels que des sandwichs et des céréales ainsi que dans des applications sans emballage telles que des albums photos ou porte-documents.
PCT/US1996/020180 1995-12-18 1996-12-18 Films de polyethylene a orientation biaxiale WO1997022470A1 (fr)

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EP96944865A EP0876250A4 (fr) 1995-12-18 1996-12-18 Films de polyethylene a orientation biaxiale
AU13369/97A AU1336997A (en) 1995-12-18 1996-12-18 Biaxially oriented polyethylene films
KR1019980704592A KR20000064446A (ko) 1995-12-18 1996-12-18 2축배향폴리에틸렌필름
JP52297797A JP2002515923A (ja) 1995-12-18 1996-12-18 二軸配向ポリエチレンフィルム
HU0001641A HUP0001641A1 (hu) 1995-12-18 1996-12-18 Biaxiálisan orientált polietilén filmek
BR9612068-1A BR9612068A (pt) 1995-12-18 1996-12-18 Pelìculas de polietileno orientadas biaxialmente
NZ326083A NZ326083A (en) 1995-12-18 1996-12-18 Biaxially oriented polyethylene films
IL12459096A IL124590A0 (en) 1995-12-18 1996-12-18 Biaxially oriented polyethylene films
NO982786A NO982786L (no) 1995-12-18 1998-06-17 Biaksialt orienterte polyetylen filmer

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000011048A1 (fr) * 1998-08-19 2000-03-02 Nova Chemicals (International) S.A. Procede de fabrication de polyethylene a double reacteurs mettant en oeuvre un catalyseur phosphinimine
US6248442B1 (en) 1998-12-31 2001-06-19 Mobil Oil Corporation Easy opening hermetically sealed film
WO2001098409A1 (fr) * 2000-06-22 2001-12-27 Exxonmobil Chemical Patents Inc. Mélange de polyéthylène très basse densité et de polyéthylène haute densité
US6800692B2 (en) 2000-06-22 2004-10-05 Exxonmobil Chemical Patents Inc. Metallocene-produced very low density polyethylenes
US7135526B2 (en) 2001-06-22 2006-11-14 Univation Technologies, Llc Very low density polyethylene and high density polyethylene blends
US7235607B2 (en) 2002-09-05 2007-06-26 Exxonmobil Chemical Patents Inc. Shrink film
US7951873B2 (en) 2006-05-05 2011-05-31 Exxonmobil Chemical Patents Inc. Linear low density polymer blends and articles made therefrom
US8709610B2 (en) 2008-10-17 2014-04-29 Dow Global Technologies Llc Biaxially oriented film which could be thermally laminated with paper and other substrates
US20160016392A1 (en) * 2013-04-25 2016-01-21 Infiana Germany Gmbh & Co. Kg Multilayer film resistant to linear tear propagation
EP3335874A1 (fr) 2016-12-15 2018-06-20 Borealis AG Articles à orientation biaxiale comprenant un polymère de polyéthylène multimodal
EP3630449A4 (fr) * 2017-05-23 2021-01-20 Jindal Films Americas LLC Films lldpe métallisés, orientés et minces
WO2021119152A1 (fr) 2019-12-09 2021-06-17 Exxonmobil Chemical Patents Inc. Films de polyéthylène orientés dans le sens machine
WO2021119158A1 (fr) 2019-12-09 2021-06-17 Exxonmobil Chemical Patents Inc. Films de polyéthylène orientés biaxialement et leur procédé de production
WO2021119155A1 (fr) 2019-12-09 2021-06-17 Exxonmobil Chemical Patents Inc. Films de polyéthylène à orientation biaxiale
US11230049B2 (en) 2019-08-21 2022-01-25 Aerostar International, Inc. Seals for aerial vehicles
CN115594909A (zh) * 2021-06-28 2023-01-13 中国石油化工股份有限公司（Cn） 冷拉伸套管膜用聚乙烯组合物及其制备方法
WO2023061645A1 (fr) 2021-10-15 2023-04-20 Perfo Knowledgy B.V. Emballage pour la conservation de produits respirants et procédé
WO2023076818A1 (fr) 2021-10-26 2023-05-04 Exxonmobil Chemical Patents Inc. Films de polyéthylène à basse densité linéaire hautement orientés ayant une aptitude au traitement et des propriétés mécaniques exceptionnelles
WO2024068914A1 (fr) 2022-09-30 2024-04-04 Basell Polyolefine Gmbh Mélange de polymères pour la production d'un film polymère biorienté

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
MXPA06010713A (es) * 2004-03-19 2006-12-15 Dow Global Technologies Inc Capas de pelicula hechas de formulaciones de polimero.
EP2083990A4 (fr) * 2006-11-21 2010-01-20 Fina Technology Polyéthylène utilisé pour produire des films et des article moulés dans un procédé qui fait appel à une tension en phase solide
JP2010270227A (ja) * 2009-05-21 2010-12-02 Tohcello Co Ltd 二軸延伸エチレン系共重合体フィルム

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5397640A (en) * 1992-03-23 1995-03-14 Viskase Corporation Biaxially oriented heat-shrinkable film
US5562958A (en) * 1991-10-15 1996-10-08 The Dow Chemical Company Packaging and wrapping film

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
MX9200724A (es) * 1991-02-22 1993-05-01 Exxon Chemical Patents Inc Mezcla termosellable de polietileno o plastomero de muy baja densidad con polimeros a base de polipropileno y pelicula termosellable asi como articulos hechos con aquellas.
EP0662988B2 (fr) * 1992-09-16 2011-03-30 ExxonMobil Chemical Patents Inc. Films souples a caracteristiques physiques ameliorees
ATE248060T1 (de) * 1993-06-24 2003-09-15 American Nat Can Co Mehrschichtige strukturen aus single-site katalysierten polymeren

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5562958A (en) * 1991-10-15 1996-10-08 The Dow Chemical Company Packaging and wrapping film
US5397640A (en) * 1992-03-23 1995-03-14 Viskase Corporation Biaxially oriented heat-shrinkable film

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0876250A4 *

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000011048A1 (fr) * 1998-08-19 2000-03-02 Nova Chemicals (International) S.A. Procede de fabrication de polyethylene a double reacteurs mettant en oeuvre un catalyseur phosphinimine
US6248442B1 (en) 1998-12-31 2001-06-19 Mobil Oil Corporation Easy opening hermetically sealed film
WO2001098409A1 (fr) * 2000-06-22 2001-12-27 Exxonmobil Chemical Patents Inc. Mélange de polyéthylène très basse densité et de polyéthylène haute densité
WO2002000436A2 (fr) * 2000-06-22 2002-01-03 Exxonmobil Chemical Patents Inc. Polyethylenes a tres faible densite a base de metallocene
WO2002000436A3 (fr) * 2000-06-22 2002-05-23 Exxonmobil Chem Patents Inc Polyethylenes a tres faible densite a base de metallocene
US6800692B2 (en) 2000-06-22 2004-10-05 Exxonmobil Chemical Patents Inc. Metallocene-produced very low density polyethylenes
US7135526B2 (en) 2001-06-22 2006-11-14 Univation Technologies, Llc Very low density polyethylene and high density polyethylene blends
US7235607B2 (en) 2002-09-05 2007-06-26 Exxonmobil Chemical Patents Inc. Shrink film
US7951873B2 (en) 2006-05-05 2011-05-31 Exxonmobil Chemical Patents Inc. Linear low density polymer blends and articles made therefrom
US8709610B2 (en) 2008-10-17 2014-04-29 Dow Global Technologies Llc Biaxially oriented film which could be thermally laminated with paper and other substrates
US20160016392A1 (en) * 2013-04-25 2016-01-21 Infiana Germany Gmbh & Co. Kg Multilayer film resistant to linear tear propagation
WO2018109112A1 (fr) 2016-12-15 2018-06-21 Borealis Ag Articles à orientation biaxiale comprenant un polymère de polyéthylène multimodal
EP3335874A1 (fr) 2016-12-15 2018-06-20 Borealis AG Articles à orientation biaxiale comprenant un polymère de polyéthylène multimodal
EP3630449A4 (fr) * 2017-05-23 2021-01-20 Jindal Films Americas LLC Films lldpe métallisés, orientés et minces
US12036724B2 (en) 2019-08-21 2024-07-16 Aerostar International, Llc Seals for aerial vehicles
US11230049B2 (en) 2019-08-21 2022-01-25 Aerostar International, Inc. Seals for aerial vehicles
WO2021119152A1 (fr) 2019-12-09 2021-06-17 Exxonmobil Chemical Patents Inc. Films de polyéthylène orientés dans le sens machine
WO2021119158A1 (fr) 2019-12-09 2021-06-17 Exxonmobil Chemical Patents Inc. Films de polyéthylène orientés biaxialement et leur procédé de production
WO2021119155A1 (fr) 2019-12-09 2021-06-17 Exxonmobil Chemical Patents Inc. Films de polyéthylène à orientation biaxiale
CN115594909A (zh) * 2021-06-28 2023-01-13 中国石油化工股份有限公司（Cn） 冷拉伸套管膜用聚乙烯组合物及其制备方法
CN115594909B (zh) * 2021-06-28 2023-12-22 中国石油化工股份有限公司 冷拉伸套管膜用聚乙烯组合物及其制备方法
NL2029437B1 (en) * 2021-10-15 2023-05-16 Perfo Tec B V Package for preserving respiring produce and method
WO2023061645A1 (fr) 2021-10-15 2023-04-20 Perfo Knowledgy B.V. Emballage pour la conservation de produits respirants et procédé
WO2023076818A1 (fr) 2021-10-26 2023-05-04 Exxonmobil Chemical Patents Inc. Films de polyéthylène à basse densité linéaire hautement orientés ayant une aptitude au traitement et des propriétés mécaniques exceptionnelles
WO2024068914A1 (fr) 2022-09-30 2024-04-04 Basell Polyolefine Gmbh Mélange de polymères pour la production d'un film polymère biorienté

Also Published As

Publication number Publication date
EP0876250A4 (fr) 2000-05-03
NO982786D0 (no) 1998-06-17
AU1336997A (en) 1997-07-14
JP2002515923A (ja) 2002-05-28
EP0876250A1 (fr) 1998-11-11
NO982786L (no) 1998-08-14
CA2239549A1 (fr) 1997-06-26
IL124590A0 (en) 1998-12-06
NZ326083A (en) 1999-01-28
HUP0001641A1 (hu) 2000-09-28
PL327143A1 (en) 1998-11-23
KR20000064446A (ko) 2000-11-06
BR9612068A (pt) 1999-12-28

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