WO2010117900A1

WO2010117900A1 - Aroma barrier films and structures

Info

Publication number: WO2010117900A1
Application number: PCT/US2010/029781
Authority: WO
Inventors: Howard S. Kravitz; Fred Levitt
Original assignee: Nanopack, Inc.
Priority date: 2009-04-08
Filing date: 2010-04-02
Publication date: 2010-10-14

Abstract

The invention concerns containers comprising a base; a coating on at least one surface of the base film comprising: (a) particles bearing a positive or negative charge; (b) film forming polymer; (c) a dispersion agent; and (d) cross-linking agent for the polymer; and a polymeric heat sealable film positioned on the coating.

Description

AROMA BARRIER FILMS AND STRUCTURES

RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Patent Application No. 61/167,554, filed April 8, 2009, the disclosure of which in incorporated herein in its entirety.

TECHNICAL FIELD

[0002] The invention relates, inter alia, to aroma barrier films and structures and methods of making same.

BACKGROUND

[0003] Barrier coatings are widely used in packaging materials to prevent the passage of a permeant molecule or composition from contacting the contents of a package or preventing the escape of package contents. Improving barrier properties is an important goal for manufacturers of films sold for containment of products such as foods, cosmetics, agricultural chemicals, and pharmaceuticals. Use of typical plastic materials is desirable because they are inexpensive. Plastics, however, are very permeable to many compositions compared to a metal or glass material as used in canning or bottling, or foil used with paper for packaging.

[0004] Barrier coatings can also serve to (a) keep a gas inside a package - e.g., a gas used in modified atmosphere packaging, or helium kept inside balloons; (b) keep moisture inside a package so that the contents do not dehydrate; or (c) keep a perfume inside a package, where perfumes can be expensive components. In all these cases, the barrier is maintaining the packaged contents. [0005] Barrier properties arise from both the structure and the composition of the material. The order of the structure, i.e., the crystallinity or the amorphous nature of the material, the existence of layers or coatings can affect barrier properties. The barrier property of many materials can be increased by using liquid crystal or self-ordering molecular technology, by axially orienting materials such as an ethylene vinyl alcohol film, or by biaxially orienting nylon films and by using other useful structures. Internal polymeric structure can be crystallized or ordered in a way to increase the resistance to permeation of a permeant. A material may be selected for a plastic or paper packaging coating that prevents absorption of a permeant onto the barrier surface, and a material may be selected to prevent the transport of the permeant through the barrier. Generally, permeation is concentration and temperature dependent. Permeability is also a function of pressure, where a gradient exists between atmospheric pressure and the structure surrounded by a coated film, etc., e.g., balloons (positive pressure) and vacuum packaging (negative pressure).

[0006] Permeation through a polymeric coating is believed to be a multi-step event. First, collision of the permeant molecule with the polymer is followed by sorption into the polymer. The permeant migrates through the polymer matrix along a random path, and finally the permeant desorbs from the polymer. Permeability of a typical molecule through a packaging film is a function of diffusion rate and solubility of the molecule. The diffusion rate measures how rapidly transport of the molecule occurs through the film, and it relates to the ease with which a permeant molecule moves within a polymer. Solubility relates to the concentration or total amount of permeant that may be present in the film. Diffusion and solubility are important measurements of barrier coating performance. Transfer of vapors through packaging films may occur by capillary flow or activated diffusion. Capillary flow involves small molecules permeating through pinholes or microscopic channels of porous media, which is generally an undesirable feature of a barrier coating. Activated diffusion entails solubilization of a permeant into an effectively non-porous medium, diffusion through the film under a concentration gradient, and release from a transverse surface at a lower concentration. Several factors determine the ability of a permeant molecule to permeate through a barrier coating, including size, shape, and chemical nature of the permeant, physical and chemical properties of the polymer, and interactions between the permeant and the polymer.

[0007] Various transparent plastic materials having unsatisfactory gas barrier properties are known. Films consisting of a thermoplastic resin, oriented films of polypropylene, polyester, polyamide or the like typically have excellent mechanical properties, heat resistance, transparency and the like and are widely used as packaging materials. However, when these films are used for packaging foods or other goods, they can be unsatisfactory for high barrier requirements to oxygen and certain package contents. Typical barrier materials are a single layer of polymer, a bilayer co-extruded or laminated polymer film, a coated monolayer, or a bilayer or multilayer film having one or more coatings on a surface or both surfaces. The most widely used barrier polymers for food packaging are ethylene-vinyl alcohol copolymers ("EVOH"), ethylene vinyl acetate copolymers ("EVA"), and polyvinylidene chloride terpolymers ("PVDC"), which offer some resistance to permeation of gases, flavors, aromas, and solvents. PVDC also offers some resistance to moisture. EVOH copolymer resins are available in a wide variety of grades having varying ethylene concentrations. As the EVOH content is increased relative to the polyethylene content, the barrier properties to gases, flavors, and solvents increase. EVOH resins are commonly used in coextrusions or laminations with polyolefins such as polyethylene and polypropylene as structural and/or sealant layers, and with nylon, polyethylene terephthalate ("PET"), poly(lactic acid) ("PLA"), or polyhydroxyalkanoate ("PHA") as structural layers. PVDC emulsions are applied as micron-thick rotogravure coatings to various base film structures such as PET, nylon, polypropylene, poly(lactic acid) ("PLA"), or polyhydroxyalkanoate ("PHA"). Other barrier technologies include metallization with thin coatings of aluminum to various base film structures using vacuum deposition. Moderate barrier polymer materials such as monolayer polyethylene terephthalate, polymethyl pentene, and polyvinyl chloride ("PVC") films are commercially available.

[0008] Still other barrier films have been achieved with very thin plasma vapor depositions of oxides of silicon or aluminum (several nanometers thick) on base films and molded polymer structures.

[0009] Another method for imparting gas barrier properties includes dispersing an inorganic material in a resin. Micron-thin polymeric coatings incorporate nano-scale particulate dispersions of clays, such as montmorillonite, hectorite, sodium terasililic mica, sodium taeniolite, and vermiculite into various water-solubilized or emulsified polymers. For example, montmorillonite, hectorite, sodium terasililic mica, or sodium taeniolite may be blended into polyvinyl alcohol. Similarly, polyvinyl alcohol / poly(acrylic acid) blends with these clays are known. In order to prevent clay or vermiculite particles from aggregating or precipitating from solution while mixed with such polymers, it must be extensively pre-treated with, for example, acetic acid or glycine. Still, it is difficult to maintain vermiculite particles in suspension.

[0010] Finally, attempts to create barrier by direct addition of various clay particles in extruded and blown thermoplastic films and molded articles are common, but have only modest improvements in barrier impermeability versus orders of magnitude improvement using the aforementioned clay-containing coatings.

SUMMARY

[0011] In some aspects, the invention concerns containers comprising: a base film; a coating disposed on at least one surface of said base film comprising:

(a) particles bearing a positive or negative charge;

(b) film forming polymer;

(c) a cationic or anionic dispersion agent; and

(d) cross-linking agent for the polymer; and a polymeric film disposed on said coating. Another aspect of the invention concerns a film comprising the base film and the coating and film described herein. Yet another aspect of the invention concerns containers described herein that contain aroma emitting or producing compositions.

[0012] Suitable particles include clay, metal oxide, carbon nanotubes, and resins. Examples of these particles include vermiculite and oxides of titanium, silver, zinc, and nylon.

[0013] In some embodiments, the film forming polymer comprises polyhydroxylic polymer, urethane-containing polymer, rubber, polyvinylidene chloride terpolymer, acrylate, polyester, or ethylene vinyl alcohol. In certain embodiments, the polyhydroxylic composition is polyvinyl alcohol (PVOH) or ethylene vinyl alcohol (EVOH, such as Kuraray EXCEVAL™). Suitable rubbers include polychloroprene, butyl rubber, acrylic rubber, or nitrile rubber.

[0014] The vermiculite can have an aspect ratio greater than 5,000. In some compositions, the amount of vermiculite is 5 to 65% of the weight of the combined weight of the polymer and the cross-linker.

[0015] Suitable dispersion agents include sodium xylene sulfonate, ammonium zirconium carbonate, anionic polyethylene wax, sodium salt of polyaspartic acid, anionic carnauba wax, or blends thereof. Other suitable dispersion agents include polyamide- epichlorohydrins such as Polycup 172 (available from Hercules).

[0016] In some embodiments, the film coating is a heat sealable film. Any suitable heat sealable film can be used in the container. Particularly suitable films include those comprising polyethylene or polypropylene.

[0017] The container can be a flexible or rigid structure and may contain a wide variety of base films. The container, for example, can be a bag, bottle, or tray. [0018] Suitable base films include polyethylene terephthalate, glycolised polyester (PET-G), nylon, biaxially oriented polypropylene, oriented polypropylene, cast polypropylene, polystyrene, polyethylene, polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl chloride, and paper. The base film may comprise a single layer or a multilayer film. Additives may be used in formation of such films. Such additives are well known to those skilled in the art and may be used to alter performance or processability of the film. Some compositions can include more than one set of layers comprising base film and first and/or second coatings.

[0019] The invention also concerns methods of preventing transmission of aroma comprising placing a composition which produces said aroma in a container of the present invention. Compounds capable of producing an aroma include compounds that produce an aroma in their initial state and those that over time change composition to produce an aroma (a composition that decays over time— garbage, for example). In some embodiments, the compound capable of producing said aroma is an oil. In certain embodiments, the oil comprises but is not limited to one or more of abies alba, achillea millefolium, amyris balsamifera, anethum graveolens, angelica archangelica, aniba rosaeodora, anthemis nobilis, apis mellifera, artemisia pallens, backhousia citriodora. boronia megastigma, boswellia carterii, cananga odorata, cananga odorata var genuine, callitris intratropica, canarium luzonicum, cedrus atlantica, cinnamomum cassia, cinnamomum zeylanicum, citrus aurantifolia, citrus aurantium, citrus aurantium, citrus aurantium, citrus bergamia, citrus limon, citrus paradise, citrus reticulate, citrus reticulata, citrus sinensis, coffea Arabica, commiphora myrrha, coriandrum sativum, cupressus sempervirens, cymbopogon citratus, cymbopogon martini, cymbopogon nardus, daucus carota, dipterocarpus turbinatus, elettaria cardamomum, eucalyptus citriodora, eucalyptus globulus, eucalyptus radiate, eugenia caryophyllata, evernia prunastri, ferula galbaniflua, foeniculum vulgare, helichrysum angustifolia, hyssopus officinalis, illicium verum, jasminum officinalis, juniperus communis, juniperus virginiana, laurus Nobilis, lavendula abrialis, lavandula hybrida, lavendula officinalis, leptospermum ericoides, leptospermum petersonii, leptospermum scoparium, litsea cubeba, matricaria chamomilla, melaleuca alternifolia, melaleuca leucadendron, melaleuca quinquenervia, melissa officinalis, mentha citrata , mentha piperita, mentha piperita v. chocolat, mentha spicata, myristica fragrans, myroxylon pereirae, myrtus communis, nardostachys jatamansi, nepeta cataria, nicotania tabacum, ocimum basilicum, oreganum majorana, oreganum vulgare, pelargonium graveolens, pelargonium roseum, petroselinum sativum, picea mariana, pimenta racemosa, pimento officinalis, pimpinella anisum, pinus sylvestris, piper nigrum, pogostemon cablin, polianthes tuberose, ravensara aromatica, rosa damascene, rosmarinus officinalis, salvia lavandulaefolia, salvia sclarea, santalum album, styrax tonkinensis, tagetes minuta, thymus vulgaris, tilia vulgaris, vanilla planifolia, verbascum Thapsus, vetiveria zizanoides, viola odorata, and zingiber officinale. In other embodiments, the oil comprises sweet orange, mentha arvensis, peppermint, cedarwood, lemon, eucalyptus globyulus, litsea cubeda, clove, or spearment.

[0020] In yet other embodiments, the compound capable of producing said aroma includes but is not limited to eugenol, chocolate, menthol, d-limonene, or cuminaldehyde. In still other embodiments, the compound capable of producing said aroma is coffee, pet food, or other aroma producing compositions. Additional end uses include containment noxious odors that result from the decompositions of various substances (organic compositions, such as garbage, for example). As used herein, "garbage" refers to discarded animal and vegetable matter such as that produced by households, industrial operations and that sent to landfills.

[0021] In another aspect, the invention concerns a container described herein which contains at least one compound capable of producing an aroma.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0022] In some embodiments, the substrate is a base film. The invention is applicable to numerous base films. For example, a barrier coating composition of the invention can be applied to various blown, cast, extruded, etc. films or articles manufactured from polymeric materials selected from polyethylene terephthalate ("PET"); biaxially-oriented polypropylene ("BOPP") and oriented polypropylene ("OPP"); cast polypropylene, polyethylene ("PE"), including high density polyethylene ("HDPE"), low density polyethylene ("LDPE"), and linear low density polyethylene ("LLDPE"); polyvinyl chloride ("PVC"), polystyrene ("PS"), biaxially oriented polystyrene, and expanded polystyrene ("EPS"); polyethylene terephthalate glycol ("PET-G"); ethylene vinyl acetate ("EVA"); ethylene vinyl alcohol ("EVOH"); polyhydroxyalkanoate ("PHA"), polylactic acid ("PLA"); and others, such as poly(acrylonitrile-co-butadiene- co-styrene) polymers, acrylic polymers such as polymethylmethacrylate, poly-«-butyl acrylate, poly(ethylene-co-acrylic acid), poly(ethylene-co-methacrylate); cellophane, cellulosics including cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate and cellulose triacetate; fluoropolymers including polytetrafluoroethylene (for example, Teflon®, a registered trademark of DuPont), poly(ethylene-co-tetrafluoroethylene) copolymers, (tetra-fluoroethylene- co-propylene) copolymers, polyvinyl fluoride polymers; polyamides such as nylon-6 and nylon-6,6, including biaxially oriented nylon; polycarbonates; polyesters such as poly(ethylene- co-terephthalate), poly(ethylene-co-l,4-naphthalene dicarboxylate), poly(butylene- cø-terephthalate); polyimide materials; vinyl films including (vinyl chloride -co-vinyl acetate) copolymers, polyvinylidene chloride, polyvinyl alcohol ("PVOH"), (vinyl chloride-co-vinylidene dichloride) copolymers; and specialty films including polysulfone, polyphenylene sulfide, polyphenylene oxide, liquid crystal polyesters, polyether ketones, and the like.

[0023] A film is a flat unsupported section of a polymeric (e.g., plastic) resin whose thickness is much smaller than its width or length. Films are generally regarded as being 0.25 millimeters or less, typically 0.01 to 0.20 mm thick. A sheet may range from about 0.20 mm to several cm, typically 0.3 to 3 mm in thickness. Films and sheets can be used alone or in combination with other sheet, fabric or structural units through lamination, coextrusion or coating. Important properties include tensile strength, elongation, stiffness, tear strength and resistance; optical properties including haze, transparency; chemical resistance such as water absorption and transmission of a variety of permeant materials including water vapor and other permeants; electrical properties such as dielectric constant; and permanence properties including shrinkage, cracking, weatherability, etc. Polymer materials can be formed into a film using a variety of processes including blown polymer extrusion, linear biaxially oriented film extrusion and by casting from molten polymer resin, monomer or polymer (aqueous or organic solvent) dispersion. These methods are well known manufacturing procedures. Skilled artisans can tailor the polymer for a particular end use by controlling molecular weight (the melt index has been selected by the polymer industry as a measure of molecular weight— melt index is inversely proportional to molecular weight, density and crystallinity).

[0024] A barrier coating composition of the invention may also be applied to a cast article, or an article made my injection molding or blow molding (such as bottles and other closures), thermoforming (e.g., trays), or stamping (e.g., trays). For casting, molten polymer resin or monomer dispersion are typically produced from polyethylene or polypropylene. Occasionally, nylon, polyester and PVC are cast. For roll coating of aqueous based acrylic urethane and PVDC, etc., dispersions are polymerized to an optimum crystallinity and molecular weight before coating. The coating composition of the invention may also be applied to bottles and trays, which are commonly made with PET, polypropylene and polystyrene. Further, a film can be used as a film closure on a rigid plastic container. Such containers can have a rectangular, circular, square, or other shaped cross-section, a flat bottom and an open top. Further, the invention may be used in the formation of blister pack packaging, clam shell type enclosures, tubs, trays, lidding and similar articles of containment. Examples of use include, but are not limited to, bottles, trays, caps, corks, gloves, and condoms. [0025] Often two or more polymer materials are joined in a coextrusion process to produce tailored film or sheet products adapted to a particular end use. One or more polymer types in two or more layers of melt are melted in separate extruders and joined together in a single coextrusion die layering single extrudates together in a single film to have a finished film with versatile properties derived from the individual layers. Layers of the different polymers or resins can be combined by parallel extrusion of the different polymers. The film can be processed conventionally and may be oriented after cooling. Films can contain a variety of additives such as antioxidants, heat stabilizers, UV stabilizers, slip agents, fillers, and anti-block agents.

[0026] Alternatively, another film process puts layers together by lamination. Still other structures might be a combination of an extrusion on top of a solid film and a co-extrusion on top of a solid film.

[0027] In addition to a film, the barrier coating composition of the invention may also be applied to an article of paper, fabric, fiber, or other material of manufacture. For example, a barrier coating may be applied to a variety of packaging formats to package a variety of items. For example, items may be packaged entirely in a pouch or bag of paper, fabric or other material of manufacture that is coated with a barrier coating of the invention. Paper products include any article of manufacture, at least a portion of which comprises paper coated in accordance with the invention.

[0028] The coated paper product substrate may be made totally of paper or partially of paper. The invention encompasses paper products made of either single or multiple layers, e.g., a paper laminate or plastic/paper laminate. In such constructions, plastic coatings are commonly extruded onto paper; clays are usually slurries that are applied to paper with a knife coater (blade on top of paper with a certain gap and pressure). The coating may be applied on one or both sides. There are paper products that are coated (clay or polymer), such that the invention could be applied on top of the clay or polymer coating.

[0029] Paper products that are designed to receive food would typically be arranged such that the coatings are not in contact with food. In this instance, a sealant layer is placed between the food and the coating layer.

[0030] Other paper products to be treated with the composition of the invention or made with paper treated in accordance with the invention include laundry soap boxes, fabric dryer sheet containers, and industrial wraps. Food containers that may also be treated with a composition of the invention include any wrapper, bag, box, cup, or other paper product capable of covering, holding, or containing a food product, whether hot or cold, wet or dry, such as hamburger wrappers, candy wrappers, pizza and cereal boxes, condiments, soup mixes, coffee, spices and bags for potato chips, peanuts and pet food, among others.

[0031] The barrier coating compositions of the invention may be applied to a film or other article of manufacture using any number of application methods, including Meyer rod; reverse gravure, direct gravure, rotogravure, and reverse rotogravure methods; flexographic printing, slot die, and spraying methods; microgravure methods; roll-coating methods such as two-roll beat coat method, bottom-feeding three-roll reverse coat method and the like; knife or blade coating methods; die coat methods; dip coat methods; bar coating methods; and combinations thereof, as well as other art-recognized techniques. When the substrate is a film or sheet, the coating method preferably comprises coating a solution of the barrier coating composition onto the surface of the substrate followed by the drying of the solution. Further heating during lamination or extrusion coating promotes additional curing of the coating. The coating layer thickness may be varied depending upon the kind of substrate and the desired barrier properties, and, in some embodiments, it is preferably about 10 μm or less, more preferably about 1 μm or less, when dry. There is no lower limit, however, and, in some embodiments, the thickness is preferably 10 nm or more— 50 nm, 100 nm, 200 nm, 500 nm, or more, in order to obtain effective gas barrier properties in certain embodiments.

[0032] As long as the salutary effects of the invention are not impaired, the barrier coating composition may contain various additives such as ultraviolet absorbers/blockers, coloring agents, antioxidants, flame retardants and the like. In some preferred embodiments, these additives have average particle sizes in the nanometer range or smaller (e.g. colloidal antimony flame retardant; nano-sized titanium dioxide and zinc oxide UV barrier).

[0033] Suitable flame retardants include halocarbons such as polybrominated diphenyl ether (PBDEs), polychlorinated biphenyls (PCBs), chlorendic acid derivates (such as dibutyl chlorendate and dimethyl chlorendate), organophosphates, organobromines, and organochlorines. Suitable inorganic compounds can also be utilized. These include aluminum hydroxide, magnesium hydroxide, halogenated phosphorus compounds, red phosphorus, antimony trioxide, antimony pentoxide, boron compounds (such as borates), and tetrakis(hydroxymethyl) phosphonium salts. Additional compounds include paraffins, polybrominated biphenyls (PBB), pentabromodiphenyl ether (pentaBDE), octabromodiphenyl ether (octaBDE), decabromodiphenyl ether (decaBDE), hexabromocyclododecane (HBCD), tri- o-cresyl phosphate, tris(2,3-dibromopropyl) phosphate (TRIS), bis(2,3-dibromopropyl) phosphate, and tris(l-aziridinyl)-phosphine oxide (TEPA). Choice of a particular flame retardant should be based with compatibility and desired properties. [0034] Any suitable UV absorbing material can be used. These materials include the oxides of titanium, zirconium, cerium and tin-doped iridium oxides (such as, titanium dioxide, zirconium dioxide, cerium dioxide, indium tin oxide), and the like.

[0035] In addition to the aforementioned additives, additional anionic compounds may be utilized. Any composition that bears a negative charge and provides a useful property to the coating composition can be utilized. Such compounds include functionalized carbon nanotubes. Suitable functional groups include a variety of traditional organic functional groups (such as carboxylic acid groups) as well as inorganic groups (such as anionic magnetic particles or anionic functionalized Tiθ₂). A review of some of possibilities for functionalized nanotubes can be found in Ebbesen, J. Phys. Chem. Sol. 1996; 57(6-8):951-5 and Rakov, Chemistry of Carbon Nanotubes In: Gogotsi Y, editor, Nanomaterials Handbook, Boca Raton, FL: CRC Press; 2006, p. 105-75.

[0036] Additional anionic additives include compounds such as TiC^ compounded with an anionic component, kaolin clays, anionic dyes and colorants, alumina, and phosphorous- containing acids. It should be noted that the additional anionic component can include anionic forms or anionic functionalized versions of the additives discussed herein.

[0037] The invention includes articles of manufacture wherein either the coating or films are subsequently laminated with an additional sealant film or extrusion coated with sealant polymers. The sealant may be applied by any means known in the art. The sealant may be one layer or it may be multiple layers. In some embodiments, the sealant is preferably selected from the group consisting of polyethylene (including linear low density polyethylene, etc.), polypropylene, and ethylene -vinyl acetate copolymer (EV acetate), poly(lactic acid) ("PLA"), polyhydroxyalkanoate ("PHA") or blends thereof.

[0038] Platelets of vermiculite are preferred over other clays because of their high aspect ratio. These vermiculite platelets preferably are 1 to 3 nanometers thick and have a surface dimension (length and/or width) of 10 to 30 microns. High aspect ratios allow numerous platelets to be held in place parallel or nearly parallel to the plane of the coating and within thin layers of coating, while having sufficient breadth to form a tortuous path to traversing molecules, such as of oxygen. An anionic polymer on non-polymeric compound is used to disperse and maintain the dispersion of vermiculite clay. Particles of vermiculite are negatively charged on their surfaces and positively charged on their edges. Without the use of a dispersant, vermiculite particles agglomerate and precipitate in the polymer solution. The use of anionic dispersants overcomes the necessity for lengthy treatment of vermiculite particles with acetic acid or glycine as described in other patents and literature, to functionalize the platelets so they do not agglomerate. [0039] Suitable dispersion agents include those bearing a negative charge to disperse the vermiculite. Some suitable agents include anionic polymers. Such anionic polymers include anionic, water-based polymer such as anionic carnauba wax, paraffin wax, or polyethylene wax. Other dispersion agents are small molecule moieties such as sodium xylene sulfonate, ammonium zirconium carbonate, and the sodium salt of polyaspartic acid. In one embodiment, these dispersion agents are used at a weight ratio of dispersion agent to vermiculite ranges from about 0.02 to about 1.0, preferably about 0.04 to about 0.5. In some embodiments, a blend of dispersion agents can be utilized.

[0040] Suitable polymers used in the compositions include those capable of forming films. Films can be formed by rolling out or laying out the polymer (or solution or suspension of polymer) on a surface and allowing it to form the film. Such films can be formed with or without the application of heat. The films can be formed with or without the presence of a solvent for the polymer.

[0041] The polymers of the invention can be delivered to the coating composition either neat or in solution. In some embodiments, the solution is an aqueous solution. In other embodiments, a non-aqueous solvent may be used. Non-aqueous solvents include alcohols (such as methanol, ethanol and isopropanol), dimethylsulfoxide, acetone, methyl ethyl ketone (MEK), and hydrocarbons.

[0042] The polymers can be delivered in the form of an emulsion in some embodiments. Urethane polymer is one such example. Another example of a useful emulsion that is based on polyvinylidene chloride (PVDC). It should also be noted that many of the rubbers noted throughout the application can also be delivered in the form of emulsions - e.g. butyl, nitrile, SBR, epichlorohydrin, chloroprene, acrylic rubbers, and the like. In some emulsions, the range of solids is from low percentages (commonly several percent) to more commonly high percentages of as high as 55-60 weight percent. In some embodiments, PVDC is at 55-60 weight percent and urethane is at 40+ weight percent. In each of these cases, the solutions may be diluted (down to 5-10 weight percent, in some cases) to permit optimal handling and application of the coating.

[0043] While a wide variety of polymers can be used in the coating, their barrier properties will vary with composition. It should be noted that starting with polymers that have good barrier properties absent the instant coatings typically improve barrier properties by several orders of magnitude. However, if the resin is not a good barrier on its own, the barrier will not be improved as much. [0044] Any polymer that forms a film of desired properties can be used with the invention. Some preferred polymers include polyhydroxylic polymer, urethanes, and rubbers. Suitable polyhydroxylic polymers include polyvinyl alcohol (PVOH) and ethylene-vinyl alcohol copolymer (EVOH) and blends thereof. One preferred PVOH is a higher hydrolyzed PVOH which is more crystalline in nature than lower hydrolyzed PVOH. Higher hydrolyzed PVOH is more crystalline and hence has better integrity (defined as better resistance to gas transmission) at higher levels of relative humidity.

[0045] PVOH is typically produced by hydrolyzing poly( vinyl acetate). In this reaction, acetate groups of poly(vinyl acetate) are replaced with alcohol groups through a hydrolysis reaction. The more acetate groups that are replaced, the greater the hydrolysis of the PVOH resin. For example, in a 95% hydrolyzed PVOH resin approximately 5% of the acetate groups remain unchanged. Similarly, in a 99% hydrolyzed PVOH resin, approximately 1% of the acetate groups remain unchanged. In the instant invention, PVOH of various degrees of hydrolysis can be used. In some cases, the degree of hydrolysis is greater than or equal to 90%, 95%, or 99%.

[0046] Any natural or synthetic rubber that gives desired properties can be used. Suitable rubbers include polychlorprene, butyl rubber, acrylic rubber, and nitrile rubber. Other synthetic rubbers include those derived from isoprene, butadiene, SBR (styrene/butadiene rubber), isobutene/isoprene, and EPDM (ethylene/propylene/butadiene).

[0047] Urethane polymers are well known to those skilled in the art. Suitable urethane polymers include those amenable to forming aqueous dispersions.

[0048] Urethane-containing polymers include polyurethanes made by techniques known in the art. In some embodiments, a polyisocyanate compound (aromatic and aliphatic) is reacted with a compound having two or more reactive terminal hydrogen atoms. In some embodiments, the isocyanate is a diisocyanate. In some embodiments, tri-functional or higher isocyanates can be utilized alone or in mixtures with diisocyanates. In some embodiments, aliphatic isocyanates are preferred.

[0049] Suitable compounds with reactive terminal hydrogens include polyols such as poly(ethylene glycol), poly(propylene glycol), or polyester polyol. These compounds can be reacted with the isocyanate compound either in the presence or absence of catalysts.

[0050] In some embodiments, the urethanes can have polar sites attached thereto to promote water compatibility. Such sites include, carboxylic acid, ether, sulfonic, sulfonium, sulfhydryl, and ammonium groups. See, for example, PCT Patent Application No. WO98/03860.

[0051] In some embodiments, the polymer can be formed in situ. A urethane, for example, can be made by reacting a polyisocyanate with suitable compounds to form urethane linkages. Such compositions might be useful in various end uses such as adhesives (a two component adhesive, for example).

[0052] In some preferred embodiments, the polymers can be cross-linked. Any suitable cross-linking agent that provides desirable properties can be used. Examples of cross-linking agents include ethanedial (Glyoxal 40 from Clariant Corporation, for example), cyclic urea glyoxal condensate (SunRez 700, for example), and ammonium zirconium carbonate. In some embodiments, the amount of cross-linker is 0.1 to 50 percent based on weight of the polymer capable of forming a film.

[0053] In some embodiments, the coating composition comprises an aqueous dispersion. In some embodiments, the weight percent of solids is 0.5 -10%. In other embodiments, the weight percent of solids is 3-8% or 4-6%.

[0054] In some embodiments, the film, article, or container can contain printing. Any suitable ink or printing method may be used. In some embodiments, the printing is done on the coating and then covered by the polymeric film. Alternately, the printing can be done on the polymeric film. In this latter case, an additional layer to protect the ink from damage may be utilized.

[0055] The invention is illustrated by the following examples which are intended as illustrative and not limiting.

Examples

[0056] A batch of 9.565 percent concentration of PVOH was prepared by dissolving 100 pounds of Celvol® 107 (Celvol is a trademark of Celanese Corporation) in 900 pounds of de-ionized water at 190 to 205⁰F. Methylparaben was added to the mixture at 0.1 percent of the weight of Celvol, or 0.1 pound to prevent formation of microbes. The solution was heated for 45 minutes before all the PVOH and methylparaben were dissolved. The solution was subsequently cooled and filtered through a 80-mesh screen to remove solid impurities. Concentration was checked using a hand-held refractometer and adjusted to account for the water evaporated during the solubilizing step. The evaporated water was replaced with de-ionized water so that the refractometer reading was 11.0 BRIX (A reading of 11.0 BRIX corresponds to a PVOH concentration of 9.565 percent based on a known relationship of BRIX reading to concentration, where the concentration of PVOH = 1.15 x BRIX.)

[0057] A coating masterbatch was prepared by mixing 6437 grams of the 9.565 percent PVOH solution with 9603 grams of de-ionized water. To this mixture was added 239 grams of

Michem® 62125AM anionic carnauba wax (Michem is the trademark of Michelman, Inc.). The mixture was gently stirred for 20 seconds. To this mixture was further added 797 grams of Glyoxal 40 from Clariant Corporation (Glyoxal 40 L is the product designation used by Clariant for ethanedial). This mixture was gently stirred for 20 seconds. This masterbatch was placed into a 5 -gallon container and transported to a production facility together with a separate container containing 1 gallon of Microlite® 963 (Microlite is the trademark of W.R. Grace & Co. - Conn., and Microlite 963 is a 7.5 percent by weight suspension of vermiculite in water).

[0058] Once at the production facility, the 5-gallon container of the masterbatch and 1992.5 grams of clay platelets were mixed together and placed into a reservoir next to a Dri-Tec waterbased coater laminater, with a machine width of 57 inches. Coating in the reservoir was pumped using a diaphragm pump to a pan in which a 140 line anal ox cylinder was partially submerged into the coating. A doctor blade applied to the cylinder maintained the correct amount of coating on the cylinder for transfer to a 37-inch wide 48 gauge PET film treated with a corona treater to 50+ dyne-cm. The coating was applied to the PET film at a machine speed of 450 feet per minute. A smoothing bar rotating opposite to the direction of the film was used to improve the uniformity of the coating on the film. A 25-foot dryer operating at 24O⁰F was used to dry the coating. The resulting coating weight was measured at 0.0034 grams per 100 cm², or a thickness of 0.27 micron, using a calculated density of the dried coating at 1.2 g/cc.

[0059] The coated PET film was then laminated to a 1.6 mil cast polypropylene (CPP) sealant film using a Nordmechanica Super Simplex solventless laminator. The adhesive used was Tycel 7668/7276, a two-part solventless urethane from Liofol. (Liofol is a division of Henkel Corporation.)

[0060] The finished laminated barrier film was subsequently formed into bags 6 inches by 6 inches using an impulse sealer.

[0061] These bags were then separately filled with various herbs and spices, including whole cloves, ground cloves, cinnamon, peppermint and orange peel powder, and were then heat sealed with an impulse sealer. The bags were placed into a heating chamber at 104⁰F (4O⁰C) for 90 days. Bags of each were placed in a freezer at -1O⁰F (-23⁰C) to function as controls. At each 30-day interval after the aging cycle commenced, several packages of each were removed from the oven and freezer and were subjectively tested for flavor and fragrance by a professional taste tester. No differences were noted at each evaluation interval over the 90-day storage cycle.

[0062] At the conclusion of the 90-day storage cycle, the samples of whole and ground cloves, cinnamon and peppermint were analyzed using a steam volatile oil (SVO) method, according to ASTA test method 5.0. The amounts of oils captured at this time interval were within the experimental error of the test methodology one (1) percentage point. See Table 1. Based on these results, it was concluded that the aged samples had not lost any volatile oils. This result was comparable to results with a standard package construction consisting of paper/polyethylene fϊlm/foil/polyethylene film, where the foil at 0.0003 inch is the barrier component. Expected loss of volatile oils without barrier is considerable at 25 to 50 percent over the course of a 90-day storage at elevated temperature.

Table 1. SVO Results (%)

Claims

What is Claimed:

1. An container comprising: a base film; a coating disposed on at least one surface of said base film comprising:

(a) particles bearing a positive or negative charge;

(b) film forming polymer;

(c) a cationic or anionic dispersion agent; and

(d) cross-linking agent for the polymer; and a polymeric film disposed on said coating.

2. The container of claim 1, wherein said polymeric film comprises a heat sealable film.

3. The container of claim 1, wherein said particle comprises clay, metal oxide, or carbon nanotubes.

4. The container of claim 1, wherein said particles comprise vermiculite.

5. The container of claim 1, wherein said particles comprise oxides of titanium or zinc.

6. The container of claim 1, wherein the film forming polymer comprises polyhydroxylic polymer, urethane-containing polymer, rubber, polyvinylidene chloride terpolymer, acrylate, polyester, or ethylene vinyl alcohol.

7. The container of claim 6, wherein the polyhydroxylic composition is polyvinyl alcohol or ethylene vinyl alcohol.

8. The container of claim 4, wherein the vermiculite has an aspect ratio greater than 5,000.

9. The container of claim 8, wherein the amount of vermiculite is 5 to 65% of the weight of the combined weight of the polymer and the cross-linker.

10. The container of claim 1, wherein said particles have a positive charge and the dispersion agent is sodium xylene sulfonate, ammonium zirconium carbonate, anionic polyethylene wax, sodium salt of polyaspartic acid, anionic carnauba wax, or blends thereof.

11. The container of claim 2, wherein the heat sealable film comprises polyethylene or polypropylene.

12. The container of claim 1, wherein the base film is polyethylene terephthalate, glycolised polyester (PET-G), nylon, biaxially oriented polypropylene, oriented polypropylene, cast polypropylene, polystyrene, polyethylene, polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl chloride, and paper.

13. A container comprising: a base film comprising at least one of polyethylene terephthalate, glycolised polyester (PET-G), nylon, biaxially oriented polypropylene, oriented polypropylene, cast polypropylene, polystyrene, polyethylene, polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl chloride, and paper; a coating disposed on at least one surface of said base film comprising:

(a) vermiculite having an aspect ratio of greater than 5,000;

(b) film forming polymer comprising at least one of polyhydroxylic polymer, urethane-containing polymer, rubber, polyvinylidene chloride terpolymer, acrylate, polyester, and ethylene vinyl alcohol;

(c) a dispersion agent bearing a negative charge; and

(d) cross-linking agent for the polymer; and a heat sealable polymeric film disposed on said coating.

14. A method for preventing transmission of aroma comprising placing a composition which produces said aroma in a container, said container being substantially composed of a composite film comprising: a base film; a coating disposed on at least one surface of said base film comprising:

(a) particles bearing a positive or negative charge;

(b) film forming polymer; (c) a cationic or anionic dispersion agent; and

15. The method of claim 14, wherein said polymeric film comprises a heat sealable film.

16. The method of claim 14, wherein said particle comprises clay, metal oxide, or carbon nanotubes.

17. The method of claim 14, wherein said particles comprise vermiculite.

18. The method of claim 14, wherein said particles comprise oxides of titanium or zinc.

19. The method of claim 14, wherein the film forming polymer comprises polyhydroxylic polymer, urethane-containing polymer, rubber, polyvinylidene chloride terpolymer, acrylate, polyester, or ethylene vinyl alcohol.

20. The method of claim 19, wherein the polyhydroxylic composition is polyvinyl alcohol or ethylene vinyl alcohol.

21. The method of claim 14, wherein the vermiculite has an aspect ratio greater than 5,000 and the amount of vermiculite is 5 to 65% of the weight of the combined weight of the polymer and the cross-linker.

22. The method of claim 14, wherein said particles bear a positive charge and the dispersion agent is sodium xylene sulfonate, ammonium zirconium carbonate, anionic polyethylene wax, sodium salt of polyaspartic acid, anionic carnauba wax, or blends thereof.

23. The method of claim 14, wherein the cross-linking agent is ethanedial, cyclic urea glyoxal condensate, ammonium zirconium carbonate, or blends thereof; said cross-linking agent being present in an amount of 0.1 to 50 weight percent of the weight of said polymer capable of forming a film.

24. The method claim 14, wherein the base film is polyethylene terephthalate, glycolised polyester (PET-G), nylon, biaxially oriented polypropylene, oriented polypropylene, cast polypropylene, polystyrene, polyethylene, polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl chloride, and paper.

25. The method of claim 14, wherein said heat sealable film comprises polyethylene or polypropylene.

26. The method of claim 14, wherein said compound capable of producing said aroma is an oil.

27 The method of claim 14, wherein said compound capable of producing said aroma is eugenol, chocolate, menthol, d-limonene, or cuminaldehyde.

28. The method of claim 14, wherein said compound capable of producing said aroma is coffee.

29. The method of claim 14, wherein said compound capable of producing said aroma comprises garbage.

30. An article comprising a container of claim 1 and at least one compound capable of producing aroma, said compound capable of producing aroma being enclosed in said container.

31. A film comprising: a base film; a coating disposed on at least one surface of said base film comprising:

(a) particles bearing a positive or negative charge;

(b) film forming polymer;

(c) a cationic or anionic dispersion agent; and

32. The film of claim 31 , wherein said base film comprises at least one of polyethylene terephthalate, glycolised polyester (PET-G), nylon, biaxially oriented polypropylene, oriented polypropylene, cast polypropylene, polystyrene, polyethylene, polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl chloride, and paper; said coating disposed on at least one surface of said base film comprises:

(a) vermiculite having an aspect ratio greater than 5,000;

(c) a dispersion agent bearing a negative charge; and