WO2015164093A1

WO2015164093A1 - Vermiculite-containing adhesive compositions

Info

Publication number: WO2015164093A1
Application number: PCT/US2015/025223
Authority: WO
Inventors: Howard S. Kravitz
Original assignee: Nanopack, Inc.
Priority date: 2014-04-21
Filing date: 2015-04-10
Publication date: 2015-10-29

Abstract

The invention concerns laminated sheets comprising first and second substrates with an adhesive mixture layer deposed between the first and second substrates, wherein said adhesive mixture comprises: (a) vermiculite, (b) adhesive capable of bonding said substrates, and (c) at least one chemical stabilizing agent comprising one or more of (i) materials that contain cationic functionality comprising at least one of lithium, alkyl C₂-C₆ ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C₃-C₆ alkyl carboxylic acids; (ii) lithium cations in combination with anions comprising at least one of carboxylic, phosphoric, phosphonic, sulfonic and fatty acids, lithium chelating agents, and lithium salts; and (iii) ammonia, C₃-C₆ amine, heterocyclic amines, lithium hydroxide, morpholine, and morpholine oleate. Other aspects include packages containing the laminated sheets and methods of making the laminated sheets.

Description

VERMICULITE- CONTAINING ADHESIVE COMPOSITIONS

RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Patent Application No. 61/981,879, filed April 21 2014, the disclosure of which is incorporated herein in its entirety.

TECHNICAL FIELD

[0002] The invention relates to vermiculite-containing adhesive compositions and their use in laminated sheets and packages for moisture and/or air sensitive compositions.

BACKGROUND

[0003] Flexible barrier packaging is commonly used for foods and other sensitive materials to maintain freshness and product quality. The requirement for packaging barrier is related to protection from oxygen and water permeation into and/or out of the package resulting in a negative change to the packaged product for example oxidation of oils which causes rancidity or to prevent absorption of water which causes sogginess and limpness. Typical materials used to enhance barrier properties for flexible packaging include materials applied directly onto flexible film surfaces such as coatings, materials applied by vacuum deposition or plasma coating and materials incorporated into the film construction as distinct barrier layers by co-extrusion or extrusion coating. Examples include:

• polymer coatings such as polyvinylidene chloride (PVDC) and polyvinylalcohol (PVA or PVOH),

• vapor deposition of aluminum

• vapor deposition of oxides of aluminum and silica (AlOx and SiOx),

• plasma deposition of aluminum to form angstrom thick coatings of aluminum metal,

• metal foils laminated to films, and

• extruded polymers such as PVDC and PVOH and ethylene vinyl alcohol (EVOH).

[0004] In some common packaging constructions a lamination of two or more films is utilized. For typical lamination packaging structures an outer film and an inner film is used, each with specific properties incorporated into the films to meet the requirements of the resultant packaging structure. Typical films used in such applications include biaxially oriented films baesd on polyethylene terephthalate (PET), polypropylene (BOPP), polyethylene (PE), nylon (BON) or polylactic acid (PLA) films. These films may be monolayer or multilayer produced by co-extrusion, extrusion coating or coating and the films may be transparent, pigmented (commonly white), or metalized. Printed graphics with inks are typically included between the outer and inner films.

[0005] The films are bonded together by application of adhesives between the outer and inner surfaces, or may be bonded together with an extruded coated thin layer of polyethylene (PE). The adhesives can be water based, organic solvent based or solventless based on a 100% adhesive composition which is applied and reacted or cured after application or applied as a hot melt.

[0006] The barrier properties of some coatings have been enhanced with the addition of various clays of alumina, boehmite, bayerite, gibbsite, diaspore, bentonite, montmorillonite, hydrotalcite, hectorite, kaolinite, mica, vermiculite or mixtures thereof. These clays form tortuous paths to the permeation of oxygen and water as well as aromas and flavors and other permeable materials. The effectiveness of clays used in the coating is a function of their aspect ratio (the length and width or breadth of the particle divided by the thickness): montmorillonite and hectorite have low aspect ratios and loadings are quite high, while loadings of vermiculite can be much lower, because their aspect ratio is quite high. While high loadings of the low aspect ratio clays can provide good barrier properties, the strength of these highly filled coatings are quite low, leading to bond failures. High loadings also adversely affect the clarity of films. The lower loadings of vermiculite are preferred, although a major technical problem has traditionally been agglomeration of the clay in the coating resulting in poor barrier properties and clarity. NanoPack's US Patent No. 8,080,297 and PCT Patent Application No. WO2013019833 teach solutions to the agglomeration problem of using vermiculite in a water based coating with the use of chemical stabilizing agents, resulting in highly effective coatings for packaging films with enhanced oxygen, flavor and aroma barrier and excellent coating transparency. SUMMARY

[0007] In some aspects the invention concerns laminated sheets comprising first and second substrates with an adhesive mixture layer deposed between the first and second substrates, wherein said adhesive mixture comprises: (a) vermiculite, (b) adhesive capable of bonding said substrates, and (c) at least one chemical stabilizing agent comprising one or more of (i) materials that contain cationic functionality comprising at least one of lithium, alkyl C2-C6 ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C3-C6 alkyl carboxylic acids; (ii) lithium cations in combination with anions comprising at least one of carboxylic, phosphoric, phosphonic, sulfonic and fatty acids, lithium chelating agents, and lithium salts; and (iii) ammonia, C3-C6 amine, heterocyclic amines, lithium hydroxide, morpholine, and morpholine oleate. In some preferred embodimetns, the vermiculite is exfoliated.

[0008] Adhesives suitable for the invention include, but are not limited to, one or more of polyurethanes, polyacrlyates, polyethylene vinyl acetates, epoxies, cyanoacrylates, starches and dextrins. Certain adhesives are an aqueous solution or emulsion. The adhesive mixture may optionally contain a cross-linking agent.

[0009] In certain embodiments, the laminated sheets have an oxygen transmission rate of less than 5.0 cc/100 in² per 24 hours at 1 atmosphere pressure, a temperature of 23°C and a relative humidity of 0%.

[0010] In some preferred embodiments, the adhesive mixture layer has a dry coat weight of between 0.5 and 7 gm/m².

[0011] Any sutiable laminated sheet may be used with the invention. In some embodiments, at least one of the first and second substrates comprises polyethylene terephthalate (PET), glycolised polyester (PET-G), nylon, biaxially oriented polypropylene (BOPP), oriented polypropylene, cast polypropylene, polystyrene, polyethylene (PE), polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl alcohol (PVOH), biaxially oriented PET, biaxially oriented PETG, biaxially oriented nylon (BON), biaxially oriented polyethylene, biaxially oriented PLA, biaxially oriented PHA, polyvinylidene chloride (PVDC), ethylene vinyl acetate (EVA), paper, metalized film or metal foil.

[0012] Another aspect of the invention concerns packages comprising at least one laminated described herein.

[0013] The invention also concerns methods of forming a laminated sheet. The method may comprise contacting first and second films with an adhesive mixture such that the adhesive mixture forms a layer which contacts said first and second films and the layer is deposed between the first and second films. In some embodiments, the adhesive mixture comprises: (a) vermiculite, (b) adhesive capable of bonding said substrates, and (c) at least one chemical stabilizing agent comprising one or more of (i) materials that contain cationic functionality comprising at least one of lithium, alkyl C2-C6 ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C3-C6 alkyl carboxylic acids; (ii) lithium cations in combination with anions comprising at least one of carboxylic, phosphoric, phosphonic, sulfonic and fatty acids, lithium chelating agents, and lithium salts; and (iii) ammonia, C3-C6 amine, heterocyclic amines, lithium hydroxide, morpholine, and morpholine oleate.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0014] The invention concerns vermiculite-containing adhesive compositions and their use in laminated sheets and packages for moisture and/or air sensitive compositions. In some embodiments, the package can be a bag, pouch overwrap or any other type of product containing package produced from two or more adhesive laminated films or substrates.

[0015] The package can consist of two or more sheets joined by adhesive. In some embodiments, at least one of the first and second films comprises polyethylene terephthalate (PET), glycolised polyester (PET-G), nylon, biaxially oriented polypropylene (BOPP), oriented polypropylene, cast polypropylene, polystyrene, polyethylene (PE), polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), biaxially oriented PET, biaxially oriented PETG, biaxially oriented nylon (BON), biaxially oriented polyethylene, biaxially oriented PLA, biaxially oriented PHA, polyvinylidene chloride (PVDC), polyvinyl alcohol (PVOH), ethylene vinyl acetate (EVA), paper, metalized film or metal foil. [0016] Any suitable adhesive may be utilized. In some embodiments, the adhesive comprises one or more of polyurethanes, polyacrlyates, polyethylene vinyl acetates, epoxies, cyanoacrylates, starches and dextrins. In some embodiments, the adhesive is an aqueous solution or emulsion.

[0017] Methods of laminating substrates are known in the art. Any suitable method may be utilized.

[0018] Typically, the adhesive layers of the invention are between 0.05μ and Ι.Ομ, preferably 0.15μ to 0.60μ thick. In some embodiments, the adhesive mixture layer has a dry coat weight of between 0.5 and 7 gm/m² (0.3 to 4.3 pounds pre ream (ppr), preferably 1 and 5 gm/m² (0.6 to 3.1 ppr)).

[0019] Suitable chemical stabilizing agents for vermiculite clay include materials that contain cationic functionality including lithium, alkyl C2-C6 ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C3-C6 alkyl carboxylic acids. Suitable chemical stabilizing agents may also be selected from materials that include C2-C6 amines, allyl amines, heterocyclic amines, morphine and ammonia.

[0020] In some embodiments, suitable chemical stabilizing agents include materials that contain cationic functionality including lithium, alkyl C2-C6 ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C3-C6 alkyl carboxylic acids in combination with anionic counter ions.

[0021] In yet other embodiments, suitable chemical stabilizing agents also include lithium cations in combination with anions selected from carboxylic, phosphoric, phosphonic, sulfonic and fatty acids, lithium chelating agents, and lithium salts.

[0022] Suitable chemical stabilizing agents include lithium salts of carboxylic and fatty acids. Also included are salts of saturated aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, caproic acid, caprylic acid, capric acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid and suberic acid; unsaturated aliphatic carboxylic acids such as acrylic acid, propiolic acid, methacrylic acid, crotonic acid, isocrotonic acid, oleic acid, maleic acid and fumaric acid; and hydroxy carboxylic acids such as lactic acid, tartaric acid, malic acid and citric acid. In some embodiments, the carboxylic acids contain at least 12 carbon atoms (lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and lanolin fatty acid, for example). In some embodiments, preferred lithium salts of carboxylic acids include lithium citrate, lithium erythorbate, and lithium stearate. These may be used alone or in combination of two or more.

[0023] Suitable chemical stabilizing agents include lithium chelating agents such as lithium CDTA (cyclohexane trans 1,2 diamino tetra acetic acid), lithium EDTA (ethylene diamine tetra acetic acid), lithium citrate, lithium tri carballylate, lithium lactate, and lithium oxalate.

[0024] Suitable chemical stabilizing agents include alkyl C2-C6 ammonium cations as linear and branched ammonium cations. In combination with anions selected from fatty acids and alkyl C2-C6 ammonium salts. In some embodiments, preferred ammonium cations are primary ammonium cations. Linear primary ammonium cations include n-propyl ammonium, n-butyl ammonium, n-pentyl ammonium, and n-hexyl ammonium. In certain embodiments, the ammonium cation is a branched C2-C6 ammonium cation. Such branched ammonium cations include 2-propanammonium, 2-butylammonium, 2-pentanammonium, 3- pentanammonium, 2-hexanammonium, and 3-hexaneammonium. In some embodiments, the preferred alkyl C2-C6 ammonium cation is n-butyl ammonium.

[0025] Suitable chemical stabilizing agents include alkyl C2-C6 amines as linear and branched amines. In some embodiments, preferred amines are primary amines. Linear primary amines include n-propyl amine, n-butyl amine, n-pentyl amine, and n-hexyl amine. In certain embodiments, the amine is a branched C2-C6 amine. Such branched amines include 2-propanamine, 2-butylamine, 2-pentanamine, 3-pentanamine, 2-hexanamine, and 3- hexaneamine. In some embodiments, the preferred alkyl C2-C6 amine is n-butyl ammonium.

[0026] Suitable chemical stabilizing agents include morpholine and morpholonium cations in combination with selected anions including carboxylic and fatty acids and morpholonium salts. In some embodiments, preferred morpholonium stabilizing agents include morpholine and morpholonium fatty acids.

[0027] Suitable chemical stabilizing agents include ammonia and ammonium cations in combinations with selected anions including carboxylic and fatty acids and ammonium salts. In some embodiments, preferred ammonium chemical stabilizing agents include ammonia and ammonium salts. [0028] Such agents can be readily obtained from commercial sources and used as is or purified by means known to those skilled in the art.

[0029] Without the use of a chemical stabilizing agent, vermiculite particles agglomerate and precipitate in the polymer solution. The use of the chemical stabilizing agents of the instant invention 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, (see, for example, US Patent No. 7078453)

[0030] Vermiculite has an aspect ratio of at least 5,000 (and commonly >10,000) and is predominantly chemically, thermally or mechanically exfoliated. In some

embodiments, the vermiculite has a particle size of 5 to 150 microns in breadth and, in some preferred embodiments, the majority of particles fall in the range of 10 to 30 microns. In some embodiments, the vermiculite particles are one to three nanometers thick.

[0031] In one embodiment, these dispersion agents are used at a weight ratio of dispersion agent to vermiculite of about 0.02 to about 3.0, preferably about 0.1 to about 2.5 or, in some embodiments, about 0.04 to about 1.0. In certain embodiments, the ratio of the chemical stabilizing agent to vermiculite platelets (dry basis) is at least 0.1, 0.15 or 0.4.

[0032] In some embodiments, a blend of dispersion agents can be utilized.

[0033] In preferred embodiments, the barriers have an oxygen transmission rate (OTR) of less than 0.7 cc/100 square inches per 24 hours at 1 atmosphere and 23°C, and preferably less than 0.4 cc/100 square inches per 24 hours at 1 atmosphere and 23°C. OTR is determined using ASTM D1434.

[0034] The invention is applicable to numerous substrates. For example, an adhesive 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-w-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- co-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.

[0035] 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 commonly 8 to 75 microns or 0.3 to 3 mils (thousandths of an inch), or typically 0.008 to 0.075 mm thick. A sheet may range from about 0.20 mm to several emm, 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 oxygen, 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 (a process referred in the film industry as tentering) 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).

[0036] Films may be transparent, pigmented (commonly white), embossed, metalized, coated, extrusion coated, coextruded. Films may consist of one or more layers. Films may contain coating(s) applied before or after or during film formation. Films of the present invention may be metalized by vacuum deposition of aluminum.

[0037] Two or more polymer materials may be 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.

[0038] In addition to a film, the adhesive composition of the invention may also be applied to an article of paper, fabric, fiber, or other material of manufacture. For example, an adhesive 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 utilizes an adhesive of the invention. Paper products include any article of manufacture, at least a portion of which comprises paper coated in accordance with the invention.

[0039] The paper product 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. [0040] 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.

[0041] 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.

[0042] Certain products can advantageously be protected from oxygen and water by the use of the protection barriers provided by this invention. It is known for example, that oxygen can cause degradation by oxidation of oils leading to rancidity, and in the case of water can lead to sogginess and a loss of product structure. Protection also comes in the form of water retention, which can lead to dehydration and a loss of product structure thru brittleness.

[0043] In addition to protection from permeation of oxygen and water into a package or water from escaping a package, the barriers of the invention can be used to prevent aromas or other materials from escaping the package.

[0044] The invention is especially advantageously applied to protect a product from contamination from permeant sources outside a packaging material. Food items are protected from contamination by aromatic and aliphatic hydrocarbons, fluorocarbons, ink, and packaging residue, exhaust from transportation equivalent and other internal combustion engines, etc. Similarly, the invention can advantageously be applied to prevent the escape of certain perfumes from the package (especially expensive perfumes) commonly used in a variety of consumer products such as scented paper products, bar soap, scented bath products, cleaners, fabric softeners, detergents, dry bleaches and disinfectants. The invention can also be applied to packaging of seasonings, spices, coffee, and the like to prevent escape of flavors.

[0045] Food items are the most common material requiring protection from outside contamination. Further, a variety of materials must be packaged in materials described herein preventing the odor of the material from exiting the package, resulting in the substantial loss of important fragrance notes from packaged materials reducing product value. Further, food odors may readily be transmitted by a variety of packaging materials, attracting insect and rodent pests. Important odors requiring substantial barriers include odors derived from coffee, ready to eat cereal, frozen pizza, cocoa or other chocolate products, dry mix gravies and soups, snack foods (such as potato or corn chips, pretzels, crackers, and popcorn), baked foods, butter or butter-flavor notes, meat products, in particular butter or butter-flavor notes used in the manufacture of microwave popcorn in microwaveable paper containers, fruits and nuts, and so on. Dry pet food (such as dog and cat food, etc.) can also benefit from the invention as it is often important to prevent obnoxious odor from escaping into the environment - in the store and at home

[0046] In other embodiments, it is desired to keep a particular gas within an article of manufacture, such as helium within a balloon, or an inert atmosphere such as nitrogen or argon within a package (including thermo-pane windows). Materials that are readily oxidized, such as reactive chemicals, may be packaged in a container in which ambient atmosphere has been replaced with an inert atmosphere, and the invention serves to exclude oxygen and to preserve the contents of the package (including the inert atmosphere).

[0047] The adhesive 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 rotogravure, and direct rotogravure methods; flexographic printing, slot die, and spraying methods; microgravure methods; roll-coating methods such as two-roll bead 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 adhesive composition onto the surface of the substrate followed by contacting the coated substrate with a second substrate. Further heating during lamination or extrusion coating promotes additional curing of the adhesive. The adhesive layer thickness may be varied depending upon the kind of substrate and the desired barrier properties, and, in some embodiments, it is preferably about 1 μιη to 3 μιη (0.6 to 1.8 pounds per ream), 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 (500 nanometers is only 0.005 micron which is too thin as an adhesive), or more, in order to obtain effective gas barrier properties in certain embodiments. The function of the barrier adhesive is to provide both barrier and adhesion, and the bulk of the adhesive is the overriding need for good bonding. In some embodiments, the coating is performed on a continuous application line at a speed of at least 10 meters per minute (30 feet per minute), preferably at least 300 meters per minute (900 feet per minute), or more for better economic efficiency.

[0048] As long as the salutary effects of the invention are not impaired, the adhesive composition may contain various additives such as ultraviolet absorbers/blockers, coloring agents, antioxidants, anti-microbials, 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; colloidal silver; nano-sized titanium dioxide and zinc oxide UV barrier).

[0049] 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.

[0050] The invention includes articles of manufacture wherein either the laminated 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, low density polyethylene, high density polyethylene, etc.), polypropylene, and ethylene-vinyl acetate copolymer (EV acetate), poly(lactic acid) ("PLA"), polyhydroxyalkanoate ("PHA") or blends thereof.

[0051] In addition, the laminated film may contain an additional moisture resistant barrier or moisture resistant coating. Any suitable barrier or coating material can be utilized. One suitable coating is an acrylic based coating; another is polyurethane based. In some embodiments, use of such a barrier or coating can protect the coating layer of the invention from humidity and extend the life of the oxygen barrier. This may be particularly valuable when the structural film has relatively poor moisture barrier (PET and PLA, for example). It should be noted that the barrier or layer can be applied to protect the coated layer from moisture that is found outside of a package utilizing a barrier coating of the invention or to protect the coated layer from moisture from moist or wet contents of the package. As such, the moisture resistant barrier can be place such that is it is on the "outside" and/or "inside" of the coating layer.

[0052] Vermiculite is preferred over other clays because of its planar nature and high aspect ratio. In particular, vermiculite that has been modified into a form with a high percentage of singular platelets is preferred. These vermiculite platelets preferably are 10 to 30 angstroms thick and have a surface dimension (length and/or width) of 10 to 50 microns and aspect ratios greater than 10,000. High aspect ratios of vermiculite single platelet length/width to thickness allow numerous platelets to be held in place parallel or nearly parallel to the plane of the coating and for numerous platelets to be closely layered within thin layers of coating, while having sufficient breadth to form a tortuous path to traversing molecules, such as of oxygen. This layered, planar alignment of vermiculite platelets, dispersed within the polymeric coating solution will be maintained during the coating application process and the coating drying process.

[0053] Vermiculite platelets are produced through a process of separation or exfoliation. Vermiculite exfoliation to highly singular platelets is known in the art and can be accomplished by mechanical, thermal or chemical means as disclosed in U.S. Patent Nos. 3,325,340; 4,885,330; 5, 102,464; and 5,326,500. Chemically dispersed vermiculite products are available from Specialty Vermiculite Corporation (formally Grace) as Microlite Vermiculite and Microlite Dispersions. Microlite Dispersions are an aqueous dispersion of chemically exfoliated vermiculite. One preferred embodiment of the invention uses Microlite 963 vermiculite.

[0054] Vermiculite is typically present in an amount of 2-65% relative to the weight of the adhesive mixture. In some embodiments, vermiculite is present in an amount of 5 to 50% relative to the weight of the adhesive mixture; 7 to 30% is preferred in some embodiments.

[0055] In some preferred embodiments, the adhesive polymers can be cross-linked. Examples of cross-linking agents include ethanedial (Glyoxal 40L from Clariant Corporation, for example), cyclic urea glyoxal condensate (SunRez 700, for example). Glyoxal is preferably not used with Liofol A8200 urethane based adhesive. Other cross-linking agents include isocyanates, acrylates and oxygen or nitrogen based chemistries (such as polyalcohols and polyamines). Polyalcohol and polyamine compounds include glycerol, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine, pentaerythritol, Ν,Ν,Ν',Ν'-tetrakis (2- hydroxypropyl) ethylenediamine, diethyltoluenediamine and dimethylthiotoluenediamine 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. See U.S. Patent Nos. 5,496,649 and 6,444,750.

[0056] The invention is illustrated by the following examples which are intended as illustrative and not limiting.

[0057] SWIRL TEST - DEFINITION: The test methodology described herein will be referred to as the "swirl test", or simply "the test". The apparatus needed for the test is a 10 ounce plastic cup with tapered walls. The cup measures approximately 2 inches in diameter at the bottom, 3 inches in diameter at the top, and approximately 4 inches in height. Liquid coating is placed into the cup and swirled vigorously for 10 minutes, with fingertips placed at the top of the cup. The speed of rotation is 120 revolutions per minute. The amount of liquid placed in the cup measures between 50 and 75 grams.

[0058] When the liquid in the plastic cup is rotated vigorously, the vermiculite platelets are in their singularized format. Thin, light-weight platelets are caught in the rotating pattern of the liquid and their surfaces line up parallel to the rotating liquid. Since the platelets are quite broad in their length and breadth at 10 to 30 microns, they are large enough to reflect light and appear to shine. The sheen or shiny reflection visually defines the swirling pattern of the liquid.

[0059] If the platelets agglomerate, the liquid becomes viscous, similar to pudding. In the worst case, the liquid appears to flocculate and has nodules much the same as applesauce. The shiny swirling pattern ceases.

Example 1

[0060] Twenty grams of Liofol A8200 urethane based adhesive and 1 gram of UR5887 epoxy curing agent both from Henkel-Liofol were rigorously mixed for 15 minutes. This mixture was diluted with 74 grams of de-ionized water, providing a solid concentration of 7.45 percent. [0061] To 10 grams of the diluted mixture described above, various amounts of Microlite 963 (exfoliated vermiculite platelets in water) at 7.5% solids (Microlite is a registered trademark of Specialty Vermiculite Corporation) were added as follows:

[0062] In each case, a swirl pattern was evident, showing that the vermiculite platelets were aligning with their surfaces parallel to the plane of the swirl. However, within 10 seconds after platelets were added to the diluted mixtures, platelets were seen to agglomerate on the bottoms of the cups in which each mixture was held; these mixtures were deemed unstable and oxygen transmission rates would not be viewed as optimum in films coated with these adhesive formulations.

Example 2

[0063] Twenty grams of Liofol A8200 urethane adhesive and 1 gram of UR5887 epoxy curing agent were rigorously mixed for 15 minutes. This mixture was diluted with 74 grams of de-ionized water containing 0.676 gram of Lithium Hydroxide monohydrate providing a solid concentration of 7.80 percent.

[0064] To 10 grams of the diluted mixture described above, various amounts of Microlite 963 at 7.5% solids were added as follows: Amount of Diluted Amount of (wet) Vermiculite as a Li+ ion as a Mixture @ 7.80% Microlite 963 added, % of resin solids % of (dry)

solids grams in the diluted Vermiculite

mixture

0.73 7.4% 21.3%

1.46 14.8% 10.7%

10 grams

2.19 22.2% 7.1%

2.92 29.6% 5.3%

[0065] In each case, a swirl pattern was evident, showing that the clay platelets were aligning with their surfaces parallel to the plane of the swirl. In no case did any of the vermiculite platelets agglomerate when the vermiculite was added to the diluted resin mixture; and over the ensuing week, no platelets were seen to agglomerate in these mixes. Application of a solution with a swirl pattern and no agglomeration over time are indicative of applied coating to films that result in coated films with high oxygen barrier properties and excellent coated film clarity and transparency. These mixtures were deemed stable and oxygen transmission rates would be viewed as optimum in films coated with these formulations.

Example 3

[0066] Twenty grams of Liofol A8200 urethane adhesive and 1 gram of UR5887 epoxy curing agent were rigorously mixed for 15 minutes. This mixture was diluted with 74 grams of de-ionized water containing 1.0645 grams of Lithium Hydroxide monohydrate providing a solid concentration of 8.00 percent.

[0067] To 10 grams of the diluted mixture described above, Microlite 963 at 7.5% solids was added as follows: Amount of Diluted Amount of (wet) Vermiculite as a Li+ ion as a Mixture @ 8.0% Microlite 963 added, % of resin solids % of (dry)

solids grams in the diluted Vermiculite

mixture

0.0 0.0% 0.0%

10 grams

6.4 65.1% 3.8%

[0068] In the case where Microlite 963 was added to the diluted mixture, a swirl pattern was evident, showing that the clay platelets were aligning with their surfaces parallel to the plane of the swirl. In no case did any of the vermiculite platelets agglomerate when the vermiculite was added to the diluted resin mixture.

[0069] The two mixtures were then applied to a 70 gauge BOPP film with a combination of a smooth cylindrical rod elevated by 38.1 μ away from the film to form a slot and a #15 Meyer Rod in two passes. After each pass, the wet coating was dried with a forced hot air dryer at a temperature of 130F, until the coating was dry to the touch. The coat weight of the dried coatings was measured at 2.41 grams per square meter, or 1.6 pounds per ream. The oxygen transmission rates of the coated films was then measured using a Model 8001 permeation testing machine from Systech/Illinois Instruments, with the results shown in the table below:

Claims

What is claimed:

1. A laminated sheet comprising first and second substrates with an adhesive mixture layer deposed between said first and second substrates, wherein said adhesive mixture comprises:

(a) vermiculite,

(b) adhesive capable of bonding said substrates, and

(c) at least one chemical stabilizing agent comprising one or more

(i) materials that contain cationic functionality comprising at least one of lithium, alkyl C2-C6 ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C3-C6 alkyl carboxylic acids;

(ii) lithium cations in combination with anions comprising at least one of carboxylic, phosphoric, phosphonic, sulfonic and fatty acids, lithium chelating agents, and lithium salts; and

(iii) ammonia, C3-C6 amine, heterocyclic amines, lithium hydroxide, morpholine, and morpholine oleate.

2. The laminated sheet of claim 1, wherein said vermiculite is exfoliated.

3. The laminated sheet of claim 1 or 2, wherein said adhesive comprises one or more of polyurethanes, polyacrlyates, polyethylene vinyl acetates, epoxies, cyanoacrylates, starches and dextrins.

4. The laminated sheet of anyone of claims 1-3, wherein said adhesive is an aqueous solution or emulsion.

5. The laminated sheet of anyone of claims 1-4, wherein said adhesive mixture additionally comprises a cross-linking agent.

6. The laminated sheet of anyone of claims 1-5 having an oxygen transmission rate of less than 5.0 cc/100 in² per 24 hours at 1 atmosphere pressure, a temperature of 23°C and a relative humidity of 0%.

7. The laminated sheet of anyone of claims 1-6, wherein said adhesive mixture layer has a dry coat weight of between 0.5 and 7 gm/m².

8. The laminated sheet of anyone of claims 1-7, wherein at least one of said first and second substrates comprises polyethylene terephthalate (PET), glycolised polyester (PET-G), nylon, biaxially oriented polypropylene (BOPP), oriented polypropylene, cast polypropylene, polystyrene, polyethylene (PE), polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), biaxially oriented PET, biaxially oriented PETG, biaxially oriented nylon (BON), biaxially oriented polyethylene, biaxially oriented PLA, biaxially oriented PHA, polyvinylidene chloride (PVDC), ethylene vinyl acetate (EVA), paper, metalized film or metal foil.

9. A package comprising at least one laminated sheet of claim 1.

10. The package of claim 9, wherein said adhesive comprises one or more of

polyurethanes, polyacrlyates, polyethylene vinyl acetates, epoxies, cyanoacrylates, starches and dextrins.

1 1. The package of claim 9 or 10 having an oxygen transmission rate of less than 5.0 cc/100 in² per 24 hours at 1 atmosphere pressure, a temperature of 23°C and a relative humidity of 0%.

12. The package of anyone of claims 9-1 1, wherein said adhesive mixture layer has a dry coat weight of between 0.5 and 7 gm/m².

13. The package of anyone of claims 9-12, wherein at least one of said first and second films comprises polyethylene terephthalate (PET), glycolised polyester (PET-G), nylon, biaxially oriented polypropylene (BOPP), oriented polypropylene, cast polypropylene, polystyrene, polyethylene (PE), polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl alcohol (PVOH), biaxially oriented PET, biaxially oriented PETG, biaxially oriented nylon (BON), biaxially oriented polyethylene, biaxially oriented PLA, biaxially oriented PHA, polyvinylidene chloride (PVDC), ethylene vinyl acetate (EVA), paper, metalized film or metal foil.

14. A method of forming a laminated sheet, said method comprising contacting first and second films with an adhesive mixture such that the adhesive mixture forms a layer which contacts said first and second films and the layer is deposed between said first and second films, wherein said adhesive mixture comprises:

(a) vermiculite,

(b) adhesive capable of bonding said substrates, and

(c) at least one chemical stabilizing agent comprising one or more

(i) materials that contain cationic functionality comprising at least one of lithium, alkyl C2-C6 ammonium, allyl ammonium, heterocylclic ammonium, morpholonium, ammonium and amino C₃-C6 alkyl carboxylic acids;

(iii) ammonia, C₃-C6 amine, heterocyclic amines, lithium hydroxide, morpholine, and morpholine oleate.

15. The method of claim 14, wherein said adhesive comprises one or more of

16. The method of claim 14 or 15 having an oxygen transmission rate of less than 5.0 cc/100 in² per 24 hours at 1 atmosphere pressure, a temperature of 23°C and a relative humidity of 0%.

17. The method of anyone of claims 14-16, wherein said adhesive mixture layer has a dry coat weight of between 0.5 and 7 gm/m².

18. The method of anyone of claims 14-17, wherein at least one of said first and second films comprises polyethylene terephthalate (PET), glycolised polyester (PET-G), nylon, biaxially oriented polypropylene (BOPP), oriented polypropylene, cast polypropylene, polystyrene, polyethylene (PE), polyvinyl chloride, polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyvinyl alcohol (PVOH), biaxially oriented PET, biaxially oriented PETG, biaxially oriented nylon (BON), biaxially oriented polyethylene, biaxially oriented PLA, biaxially oriented PHA, polyvinylidene chloride (PVDC), ethylene vinyl acetate (EVA), paper, metalized film or metal foil.