WO2013180710A1 - Film à base de propylène à orientation monoaxiale, thermoscellable, ayant une déchirure directionnelle - Google Patents

Film à base de propylène à orientation monoaxiale, thermoscellable, ayant une déchirure directionnelle Download PDF

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Publication number
WO2013180710A1
WO2013180710A1 PCT/US2012/040024 US2012040024W WO2013180710A1 WO 2013180710 A1 WO2013180710 A1 WO 2013180710A1 US 2012040024 W US2012040024 W US 2012040024W WO 2013180710 A1 WO2013180710 A1 WO 2013180710A1
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WIPO (PCT)
Prior art keywords
film
layer
propylene
ethylene
polyolefin
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PCT/US2012/040024
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English (en)
Inventor
Mark S. Lee
Harold E. Koehn
Emilio Coletta
Matthew H. Brown
Keunsuk P. Chang
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Toray Plastics (America) , Inc.
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Priority to CA2874726A priority Critical patent/CA2874726A1/fr
Priority to EP12877656.4A priority patent/EP2855149A4/fr
Priority to JP2015514971A priority patent/JP2015527943A/ja
Priority to MX2014014612A priority patent/MX2014014612A/es
Priority to PCT/US2012/040024 priority patent/WO2013180710A1/fr
Publication of WO2013180710A1 publication Critical patent/WO2013180710A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
    • B32B25/14—Layered products comprising a layer of natural or synthetic rubber comprising synthetic rubber copolymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/16—Layered products comprising a layer of synthetic resin specially treated, e.g. irradiated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B32B2250/242—All polymers belonging to those covered by group B32B27/32
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/20—Inorganic coating
    • B32B2255/205—Metallic coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/31—Heat sealable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/516—Oriented mono-axially
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2439/00—Containers; Receptacles
    • B32B2439/40—Closed containers
    • 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
    • C08J2323/10—Homopolymers or copolymers of propene
    • C08J2323/12—Polypropene
    • 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
    • C08J2323/16—Ethene-propene or ethene-propene-diene copolymers
    • 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
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—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
    • C08J2423/10—Homopolymers or copolymers of propene
    • C08J2423/14—Copolymers of propene
    • 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
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2423/02—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
    • C08J2423/16—Ethene-propene or ethene-propene-diene copolymers

Definitions

  • This invention relates to a monoaxially oriented heat sealable propylene-based film which exhibits excellent sealability and directional tearability.
  • the typical retort pouch is a laminate of several films, typically constructed of a film that can be printed for the marketing of the food product; a barrier film to inhibit the diffusion of oxygen and moisture and thus prolong the shelf-life of the product; and a sealant film which provides hermetic seals which also helps prevent ingress of gases or microbes that could shorten the shelf-life of the product or cause spoilage.
  • this sealant film must provide high seal strengths that can withstand the retorting process.
  • this sealant film is a non-oriented, cast polypropylene or polyethylene-based film. During retorting, high temperatures are used to sterilize and/or cook the contents and pressure can build up within the pouch as a result of this heating.
  • the sealant component of the pouch must be formulated to be able to withstand both the high temperatures and pressures that result from the retort process and thus, maintain the integrity of the pouch.
  • the formulation of the sealant component (as well as the other components of the pouch) must be compliant to food packaging regulations for retort applications such as stipulated by US Food and Drug Administration (FDA) 21 CFR 177. 1390, which specifies the materials that can be used to construct flexible retort packages and compliance guidelines for migratory testing.
  • Another method to impart directional tear properties could be to orient the cast polypropylene film typically used in retort applications.
  • the process of orienting such a film— either uniaxially or biaxially - typically diminishes the seal properties in that the seal initiation temperature (SIT) of the film is raised and the overall seal strengths are weaker.
  • SIT seal initiation temperature
  • this is believed to be due to the fact that the orientation process aligns the amorphous regions into a more ordered configuration, raising the Tg of the film, and thus, seal properties are poorer.
  • unoriented cast polypropylene works well as a sealant film versus, for example, biaxially oriented polypropylene film (BOPP) which generally functions poorly as a sealant film.
  • BOPP biaxially oriented polypropylene film
  • US Patent 6,541,086 describes a retort package design using an oriented polymer outer film (suitable for printing), an aluminum foil as a barrier film, a second oriented intermediate polymeric film, and a non-oriented polyolefin for the sealant film.
  • Easy-tear functionality is added by surface roughening the two oriented polymer films and overlapping them in a particular formation.
  • the particular specific order of laminating the films and the surface roughening by sandpaper provides for easy-tear properties and presumably directional tear, but this process involves additional films and extra steps to accomplish the desired tear properties.
  • US Patent 6,719,678 describes a retort package design using multiple film layers whereby the intermediate layers ("burst resistant layer”) are scored by a laser such that the score lines provide an easy-tear feature and a directional tear feature.
  • US Patent 6,846,532 describes a retort package design intended to reduce cost by enabling the reduction of layers from typically 4 plies to 3 plies.
  • the heat sealable layer is a non-oriented cast polypropylene film and no directional tear properties are cited.
  • US Patent 5,756,171 describes a retort package design using multiple layers of films including polyolefin film layers intended to protect the inner barrier layer from hydrolysis effects. These polyolefin film layers include a rubber-type elastomer mixed into an ethylene-propylene copolymer. However, there are no directional properties cited.
  • US Patent 4,903,841 describes a retort package design that utilizes non- oriented cast polypropylene films as the sealable layers, which are surface-roughened or scored in a particular manner so as to impart directional tear properties.
  • US Patent 4,291,085 describes a retort package design using a non-drawn, non-oriented cast crystalline polypropylene film as the sealable layer with specific crystalline structure and orientation of the crystalline structures which must be less than 3.0. There are no directional tear properties cited.
  • US Patent 5,786,050 describes an "easy opening" pouch design which has as the inner ply (which contacts the pouch's contents) a sealant film including linear low density polyethylene; an intermediate layer composed of an oriented polyolefin with an MD/TD ratio of greater than 2; and an outermost layer of biaxially oriented PET or nylon film.
  • the inner ply sealant of linear low density polyethylene is non-oriented.
  • the specific orientation ratios of the intermediate film imparts easy-tear properties.
  • US Patent 4,834,245 describes a pouch design having a "tearing zone” using a mono-axially oriented film with a pair of notches aligned with the tearing direction and the direction of orientation of said film.
  • the mono-axially oriented film which imparts the "tearing zone" is on the outside of the pouch and does not contact the pouch contents and is not designed or considered to be appropriate for heat- sealability.
  • US Patent Application 11/596,776 describes a pouch design including a uni- directionally stretched film.
  • the preferred embodiments describe a uni-directionally stretched polypropylene film or uni-directionally stretched polyethylene terephthalate film that imparts the easy tear property.
  • the application is silent as the sealing properties of these layers or even which layer should be the sealant film.
  • One embodiment is a monoaxially oriented film including a single layer (A) of an ethylene-propylene impact copolymer blended with an amount of metallocene- catalyzed propylene-butene elastomer and an amount of crystalline propylene homopolymer. An optional amount of metallocene-catalyzed ethylene-butene elastomer may be also blended into this single layer film.
  • This layer (A) formulation is suitable for heat sealable applications, particularly for retort packaging applications.
  • Another embodiment could include a laminate film in which a second polyolefin resin-containing layer (B) could be coextruded on one side of said layer (A).
  • This second polyolefin resin-containing layer could be considered a core or base layer to provide the bulk strength of the laminate film.
  • this core layer (B) could also include an ethylene-propylene impact copolymer.
  • the laminate could further include a third polyolefin resin-containing layer (C) on the second polyolefin resin-containing core layer (B) opposite the side with the heat sealable layer (A).
  • Other embodiments could incorporate additional layers interposed between the aforementioned layers.
  • the heat sealable layer (A) includes an amount of an ethylene- propylene impact copolymer of about 10-30 wt% ethylene-propylene rubber content.
  • the amount of impact copolymer including the (A)-layer is about 40-70 wt% of the layer.
  • a component of the (A)-layer formulation is a minority amount of
  • metallocene-catalyzed propylene-butene elastomer of about 15-30 wt% butene content.
  • the amount of this propylene-butene elastomer used in the (A)-layer is about 3-15 wt% of the (A) layer.
  • Another component of the (A)-layer is an amount of crystalline propylene homopolymer of about 30-60 wt% of the (A)-layer.
  • An optional component of the (A)-layer formulation is the use of a minority amount of metallocene-catalyzed ethylene-butene elastomer of about 15-35 wt % butene. The amount of this optional amount of ethylene-butene elastomer used in the (A)-layer is up to 10 wt% of the (A)-layer.
  • This film layer (A) is then monoaxially oriented from 3 - 7 times in the machine direction, preferably 4 - 7 times, and more preferably 4.8 to 6.0 times. This monoaxial orientation imparts a directional tear property to the film.
  • the resin formulation of the (A)-layer provides excellent seal initiation, seal strengths, and hermetic seal properties after monoaxial orientation, suitable for retort pouch applications.
  • the (A)-layer could include a sealant layer on one side of a core layer (B).
  • this core layer (B) includes a polyolefin resin-containing layer which in turn, includes a propylene homopolymer or propylene copolymer. More preferable is an ethylene-propylene impact copolymer of the same or similar type used as a component of the (A)-layer.
  • the (A)-layer can be the same thickness as the (B) core layer, but preferably is thinner than the (B)-layer, about 5-50% of the total thickness of the (A) and (B) layers combined, more preferably 10-30% of the total thickness of the laminate film structure (A) and (B) layers combined.
  • This core polyolefin resin-containing layer can also include an antiblock component selected from the group consisting of amorphous silicas, aluminosilicates, sodium calcium aluminum silicates, crosslinked silicone polymers, and polymethylmethacrylates to aid in machinability and winding.
  • Discharge-treat can be done by any of several means well known in the art, such as corona, flame, plasma, or discharge-treatment in a controlled atmosphere of selected gases.
  • the third layer (C) would be disposed on the side of the core layer (B) opposite the heat sealable layer (A) and preferably includes a polyolefin resin-containing layer which in turn, includes a polyolefin selected from the group consisting of propylene homopolymer, copolymers, terpolymers, polyethylene and combinations thereof.
  • This third polyolefin resin-containing layer can also include an antiblock component selected from the group consisting of amorphous silicas, aluminosilicates, sodium calcium aluminum silicates, crosslinked silicone polymers, and polymethylmethacrylates to aid in machinability and winding.
  • the third polyolefin layer can also be a discharge- treated layer having a surface for lamination, metallizing, printing, or coating with adhesives or inks.
  • Discharge-treatment in the above embodiments can be accomplished by several means, including but not limited to corona, flame, plasma, or corona in a controlled atmosphere of selected gases.
  • the discharge- treated surface has a corona discharge-treated surface formed in an atmosphere of C0 2 and N 2 to the exclusion of 0 2 .
  • the laminate film embodiments could further include a vacuum-deposited metal layer on the discharge-treated layer's surface.
  • the metal layer has a thickness of about 5 to 100 nm, has an optical density of about 1.5 to 5.0, and includes aluminum.
  • the laminate film is an extruded laminate film.
  • Yet another embodiment is a monoaxially oriented polyolefin film with a heat sealable layer of blends of ethylene-propylene impact copolymers with metallocene propylene-butene elastomers and crystalline propylene homopolymers to enhance heat sealing properties for flexible packaging purposes, and exhibiting particularly high seal strength retention in retort pouches post-retorting .
  • An additional embodiment provides laminate structures of heat sealable polyolefin layers and propylene-butene metallocene elastomer blend layers for heat sealable applications in flexible packaging.
  • the monoaxially oriented mono-layer film is produced via extrusion of the heat sealable layer blend through a die whereupon the molten film layer is quenched upon a chilled casting roll system or casting roll and water bath system and subsequently oriented in the machine direction and annealed or heat-set to minimize thermal shrinkage into a film.
  • the laminate film is produced via coextrusion of the heat sealable layer blend and the core layer and/or other layers through a compositing die whereupon the molten multilayer film structure is quenched upon a chilled casting roll system or casting roll and water bath system and subsequently oriented in the machine direction and annealed or heat-set into a multi-layer film.
  • All these examples can also be metallized via vapor-deposition, preferably a vapor-deposited aluminum layer, with an optical density of at least about 1.5, preferably with an optical density of about 2.0 to 4.0, and even more preferably between 2.3 and 3.2.
  • a method to improve the heat sealability of monoaxially oriented films is provided resulting in an economical, highly sealable film with excellent directional tear properties suitable for retort packaging applications, and particularly exhibiting excellent heat seal strength retention after post-retorting. This helps solve the problems associated with the prior art of directional tear retortable polyolefin substrates in packaging applications.
  • FIG. 1 is a diagram of a retort film pouch made using a laminate structure. Detailed Description of the Invention
  • the described films balance the above attributes of directional tear and heat sealablity by formulating an amount of 3-15 wt%, by weight of the film layer, of a metallocene-catalyzed propylene-butene copolymer of 15-30 wt% butene; 30-60 wt% of a crystalline propylene homopolymer; and with the remainder of the film composition including an impact copolymer resin of ca. 10-30% rubber content.
  • the laminate film includes a single-layer extruded film of: A mixed polyolefin resin layer including an isotactic ethylene-propylene impact copolymer; an amount of an amorphous metallocene-catalyzed propylene-butene elastomer; an amount of a crystalline propylene homopolymer; with an optional amount of amorphous metallocene-catalyzed ethylene-butene elastomer.
  • Another embodiment of the inventive laminate film includes a similar formulation as above, except that one side of the polyolefin resin layer is discharge-treated.
  • the mixed polyolefin resin layer includes an isotactic ethylene-propylene impact copolymer of a specific rubber content blended with a crystalline propylene homopolymer or a "mini-random" crystalline propylene copolymer; and a minority amount of metallocene-catalyzed propylene-butene elastomer; and is uniaxially oriented.
  • the amount of the impact copolymer to be used in the mixed polyolefin resin layer is about 40-70 wt % of the mixture, preferably about 40-50 wt%, and more preferably, about 43-48 wt%.
  • the impact copolymer is an isotactic ethylene- propylene copolymer with an ethylene-propylene rubber content of about 10-30 wt% of the polymer wherein the ethylene content of the rubber is about 10-80 wt% of the rubber.
  • the impact copolymer is manufactured in two reactors. In the first reactor, propylene homopolymer is produced and it is conveyed to the second reactor that also contains a high concentration of ethylene. The ethylene, in conjunction with the residual propylene left over from the first reactor, copolymerizes to form an ethylene-propylene rubber.
  • the resultant product has two distinct phases: a continuous rigid propylene homopolymer matrix and a finely dispersed phase of ethylene-propylene rubber particles.
  • the rubber content that is typically used is in the 10-30 wt% range depending on the desired end-use properties. It is this mixture of two phases - the propylene homopolymer matrix and the dispersed phase of ethylene- propylene rubber - that provides the impact resistance and toughening properties that impact copolymers are known for.
  • Ethylene-propylene impact copolymers are distinctly different from conventional ethylene-propylene random copolymers which are typically polymerized in a single reactor, generally have a lower ethylene content (typically 0.5 wt% to 6 wt%) wherein the ethylene groups are randomly inserted by a catalyst along the polypropylene backbone chain, and do not include an ethylene- propylene rubber content.
  • a suitable example of ethylene-propylene impact copolymer is Total
  • Petrochemical' s 5571 This resin has a melt flow rate of about 7 g/10 minutes at 230°C, a melting point of about 160-165°C, a Vicat softening point of about 148°C, and a density of about 0.905 g/cm 3 .
  • Another example of ethylene-propylene impact copolymer can be Total Petrochemical' s 4180 with a melt flow rate of about 0.7 g/10 minutes at 230°C, a melting point of about 160-165°C, a Vicat softening point of about 150°C, and a density of about 0.905 g/cm 3 .
  • ethylene-propylene impact copolymers can be Braskem (formerly Sunoco) Petrochemical' s TI-4015 with a melt flow rate of 1.6 g/lOminutes at 230°C and a density of about 0.901 g/cm 3 and ExxonMobil Chemical's PP7033E2 with a melt flow rate of about 8 g/10 minutes at 230°C and a density of about 0.9 g/cm 3 .
  • the crystalline propylene homopolymer used in the mixed polyolefm layer formulation is an isotactic propylene homopolymer of typically 90% or greater isotactic content as determined by 13 C NMR spectra obtained in 1,2,4- trichlorobenzene solutions at 130°C.
  • homopolymer to be used in the mixed polyolefm blend is about 30-60 wt% of the mixture, preferably about 40-55 wt%, and more preferably, about 46-53 wt%.
  • the % isotactic content can be obtained by the intensity of the isotactic methyl group at 21.7 ppm versus the total (isotactic and atactic) methyl groups from 22 to 19.4 ppm.
  • Suitable examples of crystalline propylene homopolymers are Total Petrochemical 3270, Total Petrochemical 3271, ConocoPhillips CH016, among others well-known in the industry. These resins have melt flow rates of about 0.5 to 5 g/lOmin at 230°C, a melting point of about 159 - 167°C, a crystallization temperature of about 108— 126°C, a heat of fusion of about 86 - 110 J/g, a heat of crystallization of about 105 - 111 J/g, and a density of about 0.90 - 0.91.
  • crystalline propylene homopolymers that are well-known in the industry as "mini-random" propylene homopolymers in which said homopolymer is a specific type or subset of ethylene-propylene copolymer in which the ethylene content of the copolymer is less than 1.0 wt%, typically on the order of 0.2-0.7 wt% (these are also known as
  • mini-random homopolymers perform and function similarly as true crystalline propylene homopolymers and can be used interchangeably in most cases and applications.
  • mini-random homopolymers also have similar physical properties of isotactic content, melt flow rates, crystallinity, melting points, and densities as listed previously.
  • Suitable mini-random propylene homopolymers can be those such as Total
  • the metallocene-catalyzed propylene-butene elastomer used in the mixed polyolefin resin layer is blended with the suitable isotactic ethylene-propylene impact copolymer resin and the crystalline propylene homopolymer in an amount of 3-15 wt% of the layer, preferably 4-10 wt%, and more preferably about 4-8 wt%.
  • the metallocene-catalyzed propylene-butene random elastomer preferably has 20-40 wt% butene content of the elastomer and the resulting polymer is amorphous or of low crystallinity, and is of very low density compared to typical polyethylenes, polypropylenes, and polybutenes.
  • the metallocene catalysis of such elastomers results in a narrow molecular weight distribution; typically, M w /M n is 2.0
  • Comonomer dispersion is also narrower than in a comparable Ziegler- Natta catalyzed elastomer. This, in turn, results in an elastomer which provides lower seal initiation temperature and maintains high seal strength when used as a heat sealant modifier.
  • thermoplastic elastomer can be described as any of a family of polymers or polymer blends (e.g. plastic and rubber mixtures) that resemble elastomers in that they are highly resilient and can be repeatedly stretched and, upon removal of stress, return to close to its original shape; is melt processable at an elevated temperature
  • a plastomer can be defined as any of a family of ethylene-based copolymers (i.e. ethylene alpha- olefin copolymer) that have properties generally intermediate to those of
  • thermoplastic materials and elastomeric materials with a density of less than 0.900 g/cm (down to about 0.865 g/cm ) at a molecular weight M w between about 5000 and 50,000, typically about 20,000 to 30,000.
  • Suitable and particularly preferred metallocene-catalyzed propylene-butene elastomer materials are such as those manufactured by Mitsui Chemicals under the tradename Tafmer® and grade names XM7070 and XM7080. These are propylene- butene low molecular weight, low crystallinity copolymers.
  • XM7070 is about 26 wt % butene content; XM7080 is about 22 wt% butene. They are characterized by a melting point of 75°C and 83°C, respectively; a Vicat softening point of 67 °C and 74°C, respectively; a density of 0.883-0.885 g/cm 3 ; a T g of about -15°C; a melt flow rate at 230°C of 7.0 g/10 minutes; and a molecular weight of 190,000-192,000 g/mol. XM7070 is preferred due to its higher butene content.
  • the metallocene propylene- butene elastomers are in contrast to typical ethylene-propylene or propylene-butene or ethylene-propylene-butene random copolymers used for heat sealant resin layers in coextruded BOPP films such as Sumitomo SPX78H8 or Total Petrochemical' s 8573, which are long-chain, high molecular weight polymers with significantly higher molecular weights on the order of 350,000 to 400,000 g/mol.
  • the metallocene propylene-butene elastomers are also in contrast to non- metallocene Ziegler-Natta catalyzed propylene-butene elastomers such as Mitsui Tafmer® XR110T.
  • XR110T has a butene content of about 25.6 wt% and molecular weight of about 190,185 g/mol which is similar to XM7070, but its density of 0.89 g/cm 3 , melting point of 1 10°C, and Vicat softening point of 83°C are all higher than its metallocene-catalyzed counterpart XM7070 butene-propylene elastomer.
  • the molecular weight distribution of the non-metallocene catalyzed butene-propylene elastomer XR110T is much wider than the metallocene-catalyzed butene-propylene elastomer XM7070. Consequently, the properties and heat sealable properties of a non-metallocene-catalyzed butene- propylene elastomer are much different from a metallocene-catalyzed butene- propylene elastomer.
  • nucleating agent additive can also be used in the above formulation for the mixed polyolefin resin sealant layer.
  • nucleating agents (sometimes also known in the industry as a "clarifying agent") can be added to increase the crystallinity of propylene homopolymers or copolymers.
  • the nucleating agents provide numerous nucleating sites for the propylene-based polymer to agglomerate and crystallize while in the molten state during extrusion and casting. Nucleating agents increase the onset of crystallization temperature, thus increasing the degree of crystallinity and speed of crystallization, and decreasing the average size and size range of spherulites. This also helps increase the stiffness and clarity of the film as well as reducing the impact strength slightly.
  • nucleating agents include derivatives of benzoic acid such as sodium benzoate; naturally occurring minerals such as kaolin and talc; or dibenzylidene sorbitol. Nucleating agents are most conveniently added as a masterbatch of about 10 wt% active loading in the masterbatch.
  • a suitable amount of nucleating agent masterbatch is about 0.05 - 1.0 wt% of the mixed polyolefin resin layer, preferably about 0.2 wt % (or, in terms of active nucleating agent in a 10 wt% masterbatch, about 0.02 wt% active nucleating agent).
  • a suitable and preferred nucleating agent masterbatch can be obtained from Ampacet Corporation's 403837 grade which uses a propylene homopolymer carrier resin and about 10 wt% (of the masterbatch) of Milliken Chemical's HPN-20E nucleating agent.
  • the inventors have found that the addition of nucleating agent to the mixed polyolefin resin blend layer helped to improve pre- and post-retort seal strengths in retort pouch applications.
  • a further optional amount of a metallocene-catalyzed ethylene-butene copolymer elastomer can also be added to this polyolefin sealant blend of an amount up to 10 wt% of the layer.
  • metallocene ethylene-butene copolymer elastomer in addition to the metallocene propylene-butene copolymer elastomer can help to improve further seal initiation temperature properties, although the use of metallocene ethylene-butene elastomer can sacrifice overall heat seal strengths which may be critical in some retort packaging applications.
  • a suitable and preferred metallocene-catalyzed ethylene-butene elastomer is Mitsui Tafmer® A4085S grade.
  • A4085S has a butene content of about 15-35 wt% of the polymer, a melt flow rate of about 6.7 g/10 minutes at 230°C, melting point of about 75 °C, Tg of about -65 to -50°C, Vicat softening point of about 67°C, and a density of about 0.885 g/cm .
  • a suitable amount of this metallocene ethylene-butene elastomer is 0% to about 10 wt% of the layer, preferably 3-4 wt% of the layer.
  • This mixed resin layer of impact copolymer, crystalline homopolymer, and metallocene elastomer (plus optional ingredients as desired) is typically 50 um to 200 ⁇ in thickness after monoaxial orientation, preferably between 60 ⁇ and 150 um, and more preferably between 70 um and 100 um in thickness.
  • the mixed resin layer can also be surface treated on one side with an electrical corona-discharge treatment method, flame treatment, atmospheric plasma, or corona discharge in a controlled atmosphere of nitrogen, carbon dioxide, or a mixture thereof, with oxygen excluded and its presence minimized.
  • the latter method of corona treatment in a controlled atmosphere of a mixture of nitrogen and carbon dioxide results in a treated surface that includes nitrogen-bearing functional groups, preferably at least 0.3 atomic% or more, and more preferably, at least 0.5 atomic% or more.
  • the discharge-treated mixed resin layer is then well suited for subsequent purposes of laminating, coating, printing, or metallizing.
  • an optional amount of antiblocking agent can be added to the mixed resin film layer for aiding machinability and winding.
  • An amount of an inorganic antiblock agent can be added in the amount of 100-5,000 ppm of the core resin layer, preferably 500-1000 ppm.
  • Preferred types of antiblock are spherical sodium aluminum calcium silicates or amorphous silica of nominal 6 ⁇ average particle diameter, but other suitable spherical inorganic antiblocks can be used including crosslinked silicone polymer or polymethylmethacrylate, and ranging in size from 2 ⁇ to 6 ⁇ .
  • Migratory slip agents such as fatty amides and/or silicone oils can also be optionally employed in the film layer either with or without the inorganic antiblocking additives to aid further with controlling coefficient of friction and web handling issues.
  • Suitable types of fatty amides are those such as stearamide or erucamide and similar types, in amounts of 100-5000ppm of the layer.
  • stearamide is used at 500-1000ppm of the layer.
  • a suitable silicone oil that can be used is a low molecular weight oil of 350 centistokes which blooms to the surface readily at a loading of 400-600ppm of the layer.
  • the films are to be used for metallizing or high definition process printing, it is recommended that the use of migratory slip additives be avoided in order to maintain metallized barrier properties and adhesion or to maintain high printing quality in terms of ink adhesion and reduced ink dot gain.
  • the mixed resin layer of the previously described impact copolymer, crystalline propylene homopolymer, and metallocene elastomers can be coextruded with another layer.
  • the mixed resin layer (A) could include a sealant layer on one side of a core layer (B).
  • this core layer (B) includes a polyolefm resin-containing layer which in turn, includes a propylene homopolymer or propylene copolymer.
  • the (A)-layer can be the same thickness as the (B) core layer, but preferably is thinner than the (B)-layer, about 5-50% of the total thickness of the (A) and (B) layers combined, more preferably 10-30% of the total thickness of the laminate film structure (A) and (B) layers combined.
  • This core polyolefm resin- containing layer can also include an antiblock component selected from the group consisting of amorphous silicas, aluminosilicates, sodium calcium aluminum silicates, crosslinked silicone polymers, and polymethylmethacrylates to aid in machinability and winding. Migratory slip additives such as fatty amides or silicone oils could also be added as previously described if desired. It can also be contemplated to discharge- treat the side of the core layer (B) opposite the heat sealable layer (A) in order to enhance that side for laminating via adhesives, etc. Discharge-treating can be done by any of several means well known in the art, such as corona, flame, plasma, or discharge-treatment in a controlled atmosphere of selected gases as described previously.
  • a third layer (C) would be disposed on the side of the core layer (B) opposite the heat sealable mixed resin layer (A) and preferably includes a polyolefm resin-containing layer which in turn, includes a polyolefin selected from the group consisting of propylene homopolymer, copolymers, terpolymers, polyethylene and combinations thereof.
  • This third layer (C) will generally be thinner than the core layer (B) and can be a thickness ranging 2 - 30% of the combined thickness of the 3 layers together, preferably about 5-10% of the overall thickness of the multi-layer laminate.
  • This third polyolefin resin-containing layer can also include an antiblock component selected from the group consisting of amorphous silicas, aluminosilicates, sodium calcium aluminum silicates, crosslinked silicone polymers, and polymethylmethacrylates to aid in machinability and winding and/or migratory slip additives such as fatty amides or silicone oils.
  • the third polyolefin layer can also be a discharge-treated layer having a surface for lamination, metallizing, printing, or coating with adhesives or other materials.
  • An embodiment of a mono-axially oriented polyolefin film may including a heat sealable layer comprising 25-67 wt% of an ethylene-propylene impact copolymer, 3-15 wt% of a metallocene-catalyzed propylene-butene elastomer, and 30- 60 wt % of a crystalline propylene homopolymer, wherein the film is oriented at least 3 times in a machine direction.
  • An embodiment of a laminate retort pouch may include a heat sealable layer including 25-67 wt% of a mono-axially oriented polyolefin film including an ethylene-propylene impact copolymer blended with 3-15 wt% of a metallocene- catalyzed propylene-butene elastomer and 30-60 wt % of a crystalline propylene homopolymer; oriented at least 3 times in the machine direction; and a gas barrier layer.
  • the laminate retort pouch may further include a nylon film layer , an ink receiving layer, and an adhesive to bond layers of the laminate pouch together.
  • An embodiment of a method of making a mono-axially oriented polyolefin film may include extruding a film including a heat sealable layer including 25-67 wt% of an ethylene-propylene impact copolymer, 3-15 wt% of a metallocene-catalyzed propylene-butene elastomer, and 30-60 wt % of a crystalline propylene homopolymer; and mono-axially orienting the the film at least 3 times in the machine direction.
  • the film may be a single or multi layer co-extruded film.
  • a key element is to monoaxially orient the film layer in the machine direction to a certain amount. It is this monoaxial orientation that imparts the directional or linear tearing properties that make it useful in pouching applications. It is the combination of this monoaxial orientation with the heat sealable resin formulation of isotactic ethylene-propylene impact copolymer of specified rubber content and ethylene content, metallocene-catalyzed propylene-butene elastomer of specific butene content, and crystalline propylene homopolymer that allows excellent and suitable heat seal initiation and seal strengths fit-for-use in retort pouch applications and excellent directional and linear tear properties.
  • the amount of monoaxial machine direction orientation should be about 3 - 7 times in the machine direction, preferably 4 - 7 times, and more preferably 4.8 to 6.0 times. Suitably clean and linear tear properties are found at these monoaxial orientation rates.
  • processability issues may result such as film breakage which can affect the product cost and machine efficiency; below a 3:1 machine direction orientation ratio, processability issues such as uneven film profile, gauge bands, and uneven stretch marks can occur which also can result in higher product costs and lower machine efficiencies.
  • the respective layers can be coextruded through a multi-layer compositing die such as a 2- or 3-layer die, and cast onto a chill roll to form a solid film suitable for further processing.
  • a multi-layer compositing die such as a 2- or 3-layer die
  • the respective layer is extruded through a single-layer die and cast onto a chill roll to form a solid film suitable for further processing.
  • Extrusion temperatures are typically set at 235-270°C with a resulting melt temperature at the die of about 230-250°C.
  • the individual resin components may be dry-blended as pellets together in a mixer prior to feeding to the extruder so as to have good dispersion of the components; alternatively, the individual resin components may also be melt-compounded together and pelletized prior to feeding into the extruder (although the latter adds cost, it generally ensures better mixing and dispersion of the individual components throughout the mixture).
  • the extruded sheet is cast onto a cooling drum at a speed of 6 to 15 mpm whose surface temperature is controlled between 18°C and 60°C to solidify the non- oriented laminate sheet.
  • the non-oriented laminate sheet is stretched in the longitudinal direction at about 90°C to 130°C at a stretching ratio of about 3 to about 7 times the original length, and most preferably between about 3.8 and 4.1 times, and the resulting stretched sheet is annealed or heat-set at about 130°C to 150°C in the final zones of the machine direction orientation section to reduce internal stresses and minimize thermal shrinkage and to obtain a dimensionally stable uniaxially oriented laminate sheet.
  • the typical film thickness is 50-200 um and most preferably, 70-100 ⁇ .
  • the uniaxially oriented sheet can then pass through a discharge-treatment process on one side of the film such as an electrical corona discharge treater to impart a suitable surface for lamination to other films as desired.
  • the one-side treated film is then wound into roll form.
  • One embodiment is to metallize the discharge-treated surface of the resin blend layer.
  • the unmetallized laminate sheet is first wound in a roll.
  • the roll is placed in a metallizing chamber and the metal vapor-deposited on the discharge- treated mixed resin metal receiving layer surface.
  • the metal film may include titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, gold, or palladium, the preferred being aluminum.
  • Metal oxides can also be contemplated, the preferred being aluminum oxide.
  • the metal layer can have a thickness between 5 and 100 nm, preferably between 20 and 80 ran, more preferably between 30 and 60 nm; and an optical density between 1.5 and 5.0, preferably between 2.0 and 4.0, more preferably between 2.3 and 3.2.
  • the metallized film is then tested for oxygen and moisture gas permeability, optical density, metal adhesion, metal appearance and gloss, and can be made into an adhesive laminate structure.
  • the MD-oriented Example film was adhesively laminated with an aluminum oxide (AlOx) deposited biaxially oriented polyethylene terephthalate (PET) film having a thickness of 12 ⁇ (e.g. Toray Advanced Film Co.'s BarrialoxTM 1101 HG-CX) and a commercially available biaxially oriented nylon film having a thickness of 15 ⁇ into a final laminate structure of PET / AlOx / adhesive / nylon / adhesive / Example film of interest (whose corona treated side was faced toward the adhesive).
  • the adhesive used was a commercially available retort grade two- component adhesive (e.g. Dow Adcote 812 with crosslinker 9L19); typical target thickness of the adhesive was 3.5 ⁇ after drying.
  • a pouch was made using the said laminate structure such that the Example film was arranged to be the inside surface of the pouch.
  • the pouch is made by folding over the laminate film to form the bottom of the pouch ("A"); the sides of the pouch ("B") are heat-sealed at suitable conditions to ensure a strong weld (see “Test Methods” for example sealing temperatures and conditions) with the heat-sealed area of about 12- 13mm in width ; and the mouth or top of the pouch (“C”) was left open.
  • the pouch was filled with about 200g of distilled water and the mouth or top of the pouch ("C") was totally sealed. (If desired, foodstuffs may also be used such as pet food or vegetables or stews or soups.) The filled pouch was subjected to retort sterilization condition of 120° C for 30 minutes.
  • the pouch was cut open at the bottom of the pouch ("A") and the contents discharged.
  • the pouch's side seals "B” and the top seal “C” was tested for "post-retort” seal strength.
  • the desired post-retort seal strength of the side and top seals made from the Examples was minimum 35 N/15mm (5950 g 25mm) and preferably about 45 N/15mm (7650 g/25mm).
  • test pouches were also sealed with contents as in step 3 but not subjected to retorting conditions.
  • the contents were discharged after sealing top seal area "C" and the side seals "B” and top seal “C” were tested for seal strengths for evaluation of "pre-retort" seal strengths. Desired values for pre-retort seal strengths were typically about 45 N/15mm (7650 g/25mm).
  • a notch can be made in either side of the pouch's side seals "B" simply by using scissors to snip a small slit on the edge of the side seal.
  • the slit should not extend through the width of the sealed area and into the pouch interior; otherwise, this would compromise the integrity of the sealed pouch and allow its contents to become contaminated or leak out.
  • This slit or notch can then be used to evaluate the directional tear properties of the example pouch as described in the "Test Methods" section of this application.
  • a single-layer extrusion article including a mixed resin layer of an ethylene- propylene impact copolymer Braskem TI-4015 at about 48 wt% of the layer, crystalline propylene homopolymer Total 3271 at about 48 wt%, and about 4 wt% of metallocene-catalyzed propylene-butene elastomer Mitsui XM7070 was extruded and cast and monoaxially oriented in the machine direction at a 4.0: 1.0 stretch ratio.
  • the resin components were dry-blended together and extruded in a single-screw extruder and cast using a matte finish chill roll. The total thickness of this film substrate after monoaxial orientation was ca. 70 ⁇ .
  • the film was passed through a corona treater for discharge treatment on one side of the film and wound into roll form.
  • the film was tested for directional tear performance, haze, and heat sealability properties.
  • the Example film was than adhesively laminated to an aluminum oxide coated PET film and a biaxially oriented nylon film and made into pouches for retorting purposes as described previously.
  • the Example film includes the interior surface of the pouch.
  • the pouch was then filled with water and retorted at 120°C for 30 minutes, allowed to cool, and then the side and top seals were tested for seal strengths for post-retort values.
  • the pouch's side and top seals were also tested for seal strengths prior to retorting to obtain pre-retort values.
  • Directional tear properties were also evaluated on both the unlaminated Example film and the pouch made of the Example film.
  • Example 1 was repeated except that the mixed resin layer was changed to about 46 wt% Braskem TI-4015 impact copolymer, about 46 wt% Total 3271 homopolymer, and about 8 wt% Mitsui XM7070 metallocene elastomer.
  • Example 1 was repeated except that the mixed resin layer was changed to about 43 wt% Braskem TI-4015 impact copolymer, about 53 wt% Total 3271 homopolymer, and about 4 wt% Mitsui XM7070 metallocene elastomer.
  • Example 1 was repeated except that the mixed resin layer was changed to about 47.9 wt% Braskem TI-4015 impact copolymer, about 47.9 wt% Total 3271 homopolymer, about 4 wt% Mitsui XM7070 metallocene elastomer, and also contained about 0.2 wt% of a nucleating agent masterbatch Ampacet 403837. Comparative Example 1
  • a single-layer extrusion article including a mixed resin layer of an ethylene- propylene impact copolymer Braskem TI-4015 at 92 wt% of the layer and 8 wt% of metallocene-catalyzed propylene-butene elastomer Mitsui XM7070 was extruded and cast and monoaxially oriented in the machine direction at a 4.0: 1.0 stretch ratio. No crystalline propylene homopolymer was used in this example.
  • the resin components were dry-blended together and extruded in a single-screw extruder and cast using a matte finish chill roll. The total thickness of this film substrate after monoaxial orientation was ca. 70 ⁇ .
  • the film was passed through a corona treater for discharge treatment on one side of the film and wound into roll form.
  • the film and pouch made from the comparative example film was tested for directional tear performance, haze, and heat sealability properties.
  • Comparative Example 1 was repeated except that it was not oriented in the machine direction; i.e. the machine direction orientation was at a 1.0:1.0 stretch ratio.
  • Comparative Example 2 was a non-oriented film using the formulation blend of impact copolymer Braskem TI4015 and metallocene propylene-butene elastomer Tafmer XM7070 at 92% and 8% of the weight of the film, respectively.
  • This composition had excellent pre- and post-retort seal strengths for both side and top seals of the pouch, well above the desired minimum of 35
  • Comparative Example 1 (CEx 1) was oriented in the machine direction at a stretch ratio of 4.0: 1.0 and showed excellent directional tear properties and was rated a "1". Tear was even and parallel to the pouch top and no stress-whitening observed.
  • pre-retort pouch top and side seal strengths were good (i.e. above 35 N/15mm), they were noticeably lower than CEx 2's results. This indicated the loss of seal strength performance due to the machine direction orientation for improved tear property.
  • post-retort side and top seal strengths of the pouch were noticeably lower than pre-retort values and below the desired value of 35 N/1 mm.
  • the post-retort seal strengths of this Example were considered
  • Example 1 (Ex 1) showed a film that used a formulation including the Braskem impact copolymer, the Mitsui metallocene elastomer, and the Total crystalline propylene homopolymer as shown in the Table. This Example was monoaxially oriented at 4.0 MDX stretch ratio. This example's pre- and post-retort side and top heat seal strengths were satisfactory and met the desired target of 35 N/15mm or better. Moreover, directional tear remained extremely good with the tear propagating cleanly from the notch with no stress-whitening or deformation, and the tear itself being very straight-edged and parallel to the machine direction of the sheet and was rated a "1". Ex. 1 's directional tear was considered to be excellent and its pre- and post-retort heat seal performance acceptable.
  • Example 2 (Ex 2) showed a film that used a similar formulation as Ex 1 but with slightly different proportions of the impact copolymer, propylene homopolymer, and metallocene elastomer, and was monoaxially oriented at 4.0 MDX stretch ratio.
  • This Example's pre- and post-retort side and top heat seal strengths remained very good and fit-for-use, and improved over Ex 1 's seal strength performance.
  • Example 3 (Ex 3) showed a film that used a similar formulation as Ex 1 but had a higher amount of crystalline homopolymer at 53 wt% and a lower amount of impact copolymer at 43 wt%.
  • Ex 3 was monoaxially oriented at 4.0 MDX stretch ratio.
  • This Example's pre- and post-retort side and top heat seal strengths were very good and remained fit-for-use; Ex 3 exhibited further improvement in post-retort seal performance over Ex 1 and Ex 2.
  • Directional tear was also extremely good (rated "1") with the tear propagating cleanly from the notch with no stress-whitening or deformation, and the tear itself being very straight-edged and parallel to the machine direction of the sheet.
  • Example 4 was similar to Ex 1 's formulation except that an amount of nucleating agent masterbatch was added at about 0.2 wt%. The addition of this nucleating agent appeared to improve pre- and post-retort top and side seal strength performance over Ex 1. Directional tear remained very good, being rated a "1".
  • Heat seal strength Measured by using a Sentinel sealer model 12 ASL at 25 psi (ca. 17.2 N/cm ), 1.0 second dwell time, with heated flat upper seal jaw Teflon coated, and unheated lower seal jaw, rubber with glass cloth covered.
  • the film sample is heat-sealed to itself at the desired seal temperature(s) in the Sentinel sealer (e.g. 310°F or 154.4°C).
  • the test film can be laid onto a heat-resistant film such as a biaxially oriented nylon or 4
  • polyethylene terephthalate film PET
  • PET polyethylene terephthalate film
  • the test film should be inserted between the heat sealer's jaws such that the film's machine direction is perpendicular to the heat sealer jaws.
  • Heat seal temperatures may be increased at desired intervals, e.g. 10°F (5.56°C) increments.
  • the respective seal strengths are measured using an Instron model 4201 tensile tester. The heat-sealed film samples are cut into 1-inch (ca.
  • the preferred value is minimum 5950 g in (ca. 35 N/15mm) at 350°F (ca. 176.7°C) seal temperature for both pre- and post-retort conditions.
  • the pouch was cut apart parallel to the side seals and parallel to the top seal, leaving tails or wings on each side of the sealed area.
  • the sealed areas were then cut crosswise in ca. 1" or 25.4 mm wide sections.
  • the two tails of the sealed section were placed in the Instron 4201 jaws and peak and average seal strengths recorded.
  • Seal initiation temperature Heat seal initiation temperature (SIT) was measured by using a Sentinel sealer model 12 ASL at 25 psi (ca. 17.2 N/cm ), 1.0 second dwell time, with heated flat upper seal jaw Teflon coated, and unheated lower seal jaw, rubber with glass-cloth covered. The film sample is heat-sealed to itself at various desired seal temperatures in the Sentinel sealer and then the respective seal strengths are measured using an Instron model 4201 tensile tester as discussed above for heat seal strength determination.
  • the Seal Initiation Temperature is defined as the seal temperature at which the film demonstrated a minimum of 2000 g/in (ca. 11.76 N/15mm) heat seal strength.
  • the preferred SIT value is maximum 330°F (ca.
  • Transparency of the film was measured by measuring haze of a single sheet of film substantially in accordance with ASTM D1003. Preferred haze value is 75% or less.
  • Directional tear is tested qualitatively by notching a piece of test film on the edge and tearing by hand at the notch to initiate the tear.
  • the notch is made parallel to the machine direction and the tear will be propagated along the machine direction.
  • the tear is initiated from the notch by hand and observation made as to whether any stress-whitening or deformation occurs. As the tear is propagated, the consistency of the torn edges and the angle at which the tear propagates is observed.
  • the preferred observation for good directional tear property is: 1) no stress-whitening or
  • Rank 3 (Marginal): torn edges are consistent and propagate cleanly; the tear propagates likely (more than 80%) in a straight line from the notch across the width of the sheet parallel to the machine direction. Few stress-whitening or deformation is observed occasionally.
  • Rank 4 (Not acceptable): stress- whitening or deformation is likely observed, torn edges are not consistent and do not propagate cleanly, the tear often propagates in an angled direction from the desired (machine) direction.
  • Rank 5 the tear initiation at the notch shows stress-whitening or deformation; and/or the tear propagation is ragged, or is non-linear or non-parallel to the machine direction of the film, is propagated at an angle to the machine direction edge of the film
  • wetting tension of the surfaces of interest was measured substantially in accordance with ASTM D2578-67.
  • the preferred value was an average value equal to or more than 40 dyne/cm (400 ⁇ ) with a minimum of 38 dyne/cm (380 ⁇ ).

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Abstract

L'invention concerne un film à orientation monoaxiale, comprenant un copolymère résistant aux chocs éthylène-propylène et 3-15 % en poids d'un élastomère propylène-butène catalysé par métallocène et 30-60 % en poids d'un homopolymère de propylène cristallin qui est orienté au moins 3 fois dans le sens machine et présente d'excellentes propriétés de déchirure directionnelle linéaire dans le sens machine pour des applications de sachet stérilisable et a une excellente performance de thermoscellage à la fois pré et post-stérilisation en autoclave. Ces formulation et orientation de film sont appropriées pour des applications de sachet nécessitant une caractéristique de déchirure linéaire « facile à déchirer » et d'excellentes propriétés de scellage hermétique, en particulier pour des sachets stérilisables.
PCT/US2012/040024 2012-05-30 2012-05-30 Film à base de propylène à orientation monoaxiale, thermoscellable, ayant une déchirure directionnelle WO2013180710A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
CA2874726A CA2874726A1 (fr) 2012-05-30 2012-05-30 Film a base de propylene a orientation monoaxiale, thermoscellable, ayant une dechirure directionnelle
EP12877656.4A EP2855149A4 (fr) 2012-05-30 2012-05-30 Film à base de propylène à orientation monoaxiale, thermoscellable, ayant une déchirure directionnelle
JP2015514971A JP2015527943A (ja) 2012-05-30 2012-05-30 方向引裂性を有するヒートシール性１軸配向プロピレン系フィルム
MX2014014612A MX2014014612A (es) 2012-05-30 2012-05-30 Pelicula basada en propileno monoaxialmente orientada sellable con calor con ruptura direccional.
PCT/US2012/040024 WO2013180710A1 (fr) 2012-05-30 2012-05-30 Film à base de propylène à orientation monoaxiale, thermoscellable, ayant une déchirure directionnelle

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PCT/US2012/040024 WO2013180710A1 (fr) 2012-05-30 2012-05-30 Film à base de propylène à orientation monoaxiale, thermoscellable, ayant une déchirure directionnelle

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WO2013180710A1 true WO2013180710A1 (fr) 2013-12-05

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EP (1) EP2855149A4 (fr)
JP (1) JP2015527943A (fr)
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2962953A1 (fr) * 2014-06-30 2016-01-06 Cargal Flexible Packaging Ltd. Sacs de polypropylène recyclable
WO2016027885A1 (fr) * 2014-08-22 2016-02-25 三井化学株式会社 Film stratifié, et sac d'emballage mettant celui-ci en œuvre
WO2016161330A1 (fr) * 2015-04-01 2016-10-06 Printpack Illinois, Inc. Films à couches multiples pour processus de stérilisation ou de pasteurisation
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EP2962953A1 (fr) * 2014-06-30 2016-01-06 Cargal Flexible Packaging Ltd. Sacs de polypropylène recyclable
WO2016027885A1 (fr) * 2014-08-22 2016-02-25 三井化学株式会社 Film stratifié, et sac d'emballage mettant celui-ci en œuvre
JPWO2016027885A1 (ja) * 2014-08-22 2017-04-27 三井化学株式会社 積層フィルムおよびそれを利用した包装袋
US10639871B2 (en) 2014-08-22 2020-05-05 Mitsui Chemicals, Inc. Laminate film and packaging bag using same
WO2016161330A1 (fr) * 2015-04-01 2016-10-06 Printpack Illinois, Inc. Films à couches multiples pour processus de stérilisation ou de pasteurisation
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US11396168B2 (en) 2016-09-28 2022-07-26 Printpack Illinois, Inc. Microwaved multi-ply structures, microwaved packages, and methods of sterilization
CN116215031A (zh) * 2022-12-16 2023-06-06 青岛振昌工贸有限公司 一种耐高温蒸煮复合膜及其制备方法及耐高温蒸煮袋
CN116215031B (zh) * 2022-12-16 2023-09-26 青岛振昌工贸有限公司 一种耐高温蒸煮复合膜及其制备方法及耐高温蒸煮袋

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EP2855149A1 (fr) 2015-04-08
MX2014014612A (es) 2015-07-06
EP2855149A4 (fr) 2016-04-06
JP2015527943A (ja) 2015-09-24
CA2874726A1 (fr) 2013-12-05

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