HK1171718B - Printed flexible film for food packaging - Google Patents

Description

Printed flexible film for food packaging

Cross Reference to Related Applications

Priority is claimed to U.S. provisional application serial No. 61/236,907, 8/29 on application date 2009, the disclosure of which is incorporated herein by reference.

Background

The present invention relates to food packaging material in the form of a flexible film having a printed image.

In order to provide a food packaging film having improved barrier properties, a multilayer film of two or more synthetic resins is generally used. Examples include coextruded polyethylene/polypropylene ("coextrusion") laminated to polyethylene terephthalate (PET), PET laminated to LDPE (low density polyethylene), and metallized PET laminated to "coextrusion". Other such multilayer food packaging films may be formed from nylon, metal foil, and ethylene vinyl acetate polymers and copolymers.

When it is desired to provide such a laminated packaging film with a printed image, the image is typically printed onto the outside of the film, i.e. on the major face of the film not facing the food product in the package. When a transparent or translucent packaging film is used, the image may instead be printed onto the inner face of the film.

To protect these printed images from damage due to friction, flexing, abrasion and heat sealing, these printed images are typically covered with a suitable barrier coating or "trap-print film". See us patent No. 7,063,882 to Mossbrook et al, the entire disclosure of which is incorporated herein by reference. If so, these interlayer printing films (trap-printfilms) are typically made of materials suitable for direct food contact ("food-compatible materials"), even if the image is printed on the outside of the packaging film. Since most packaging films are provided in large rolls, when the film itself is wound to form a roll, a trap-print film (print film) on the outer face of the film comes into contact with the inner face of the film. Therefore, even if printed on the outside of the packaging film, a sandwich printed film (trap-printfilm) is generally prepared from a food-compatible material to prevent contamination of the food-contact inner face of the film.

The interlayer print film (trap-printfilm) may be applied to the printed packaging film by any conventional process. For example, a sandwich printed film (trap-printfilm) may be applied by extrusion coating, if desired. However, extrusion coating typically requires long production runs to be economically viable due to the time required to set up the extruder and the considerable waste generated when starting and stopping the extruder.

A sandwich printed film (trap-printfilm) may also be applied by adhesive bonding lamination. However, this approach limits the inks that can be used for printing to those that maintain very low solvent levels so as not to adversely affect the bond strength of the subsequently applied adhesive. These adhesives typically exhibit low bond strength prior to curing, which can lead to undesirable bubble formation and/or "tunneling". In addition, the complete curing of these adhesives can be slow, which often requires storage of the films before the process is complete, which in turn increases capital costs. In those cases where two-component adhesives are used, these adhesives must be removed if not applied quickly enough, which also increases costs.

To avoid these problems, it has also been proposed to form such a sandwich printed film (trap-printfilm) from an electron beam activated coating. However, electron beam curing equipment is not widely available in the food packaging industry. Furthermore, the equipment and materials used in e-beam coating are often expensive.

Disclosure of Invention

According to the present invention, these problems are avoided by forming such a sandwich printed film (trap-printfilm) from shellac or the like.

Accordingly, the present invention provides a flexible film substrate comprising a material exhibiting better resistance to oxygen and water vapor permeability than paper, said flexible film substrate having a pair of opposing major faces, a printed image on at least one major face, and a barrier coating overlying said printed image, said barrier coating comprising a non-water vapor permeable, food compatible film forming material of organic origin.

Also provided are packaged food products comprising a food product packaged by such food packaging films.

Detailed Description

Flexible film substrate

Essentially any material that has been used before or in the future for forming flexible packaging films for food products with improved barrier properties can be used as the flexible film substrate of the present invention. In this context, "food product" is understood to include both liquid and semi-solid, such as pudding and gelatin, as well as traditional solid food products. Furthermore, "improved barrier properties" are understood to mean materials which are used to form substrates which exhibit better resistance to oxygen and water vapour permeability than paper. Thus, the substrate of the food packaging film of the present invention can be prepared from a variety of different synthetic resins such as polyethylene (LDPE, LLPE, VLDPE, HDPE, MDPE), polypropylene, polyethylene terephthalate, nylon, other vinyl polymers and copolymers such as those prepared from vinyl acetate, vinyl alcohol, vinyl chloride, and the like. In addition, the base material of the food packaging film of the present invention may also be made of a metal foil such as aluminum foil or the like. Furthermore, the substrate of the food packaging film of the present invention may also be made of a variety of different natural film-forming resins, particularly those that are degradable, biodegradable or compostable.

A degradable resin is a resin that undergoes a significant change in its chemical structure under specific environmental conditions, resulting in the loss of some property. The biodegradable resin is a degradable resin degraded by natural microorganisms such as bacteria, fungi and the like. Compostable resins are biodegradable resins that biodegrade as a form of cellulose to non-toxic and broken down decomposition products over a similar period of time.

Biodegradable resins are typically derived from renewable raw materials such as starches (e.g., corn, potato, tapioca, and the like), cellulose, soy protein, lactic acid and the like. They are not hazardous in production and typically break down into carbon dioxide, water and biomass, etc. when discarded. Corn starch is the major raw material currently used to make bioplastic resins. Mater-Bi (major component corn starch) and Polylactide (PLA) (also made from corn starch) are currently two major resins (raw materials) used today for the production of compostable and biodegradable resins and certified compostability under the standards set by the international organization. However, other bio-plastics that are introduced into the market are manufactured from potato starch, soy protein, cellulose, etc. Currently, most of these bioplastics are not certified compostability, although some are certified biodegradable. The field of bioplastics continues to advance as new materials and technologies emerge and enter the market.

Preferred biodegradable resins ("bioplastics") are those that are not only biodegradable, but also compostable. Particularly preferred bioplastics conform to ASTM-6400 for compostable plastics. As described therein, a compostable plastic meeting this standard is "capable of biodegrading" in a composting location as part of the available procedures so that the resin is not visually identifiable and breaks down into carbon dioxide, water, inorganic compounds and biomass at a rate consistent with known compostable materials (e.g., cellulose), and leaves no toxic residue.

Under ASTM-6400, a resin is compostable if it exhibits some minimum level of biodegradability, ability to break, and nontoxicity. Under the standard, e.g. CO produced by the decomposition₂If at least 60% of the resin biodegrades within 180 days, the resin is biodegradable. Under this standard, the resin is breakable if less than 10% of its decomposition products remain on a 2mm screen when screened. Under this standard, the resin is non-toxic if its decomposition products have heavy metal contents kept below certain given limits and, moreover, when combined with soil in different concentrations, it is able to support a certain level of plant growth relative to the control compost.

Compostable resins, and packaging materials and other articles made therefrom, are described in a number of recently published and/or granted patent documents, examples of which include: U.S.7,083,673, US2008/0153940, US2008/0113887, US2007/0259139, US2007/0203283, US2007/0148384, US2007/0129467, US2004/0217087, US2005/0192377, US2005/0039689, US2004/0059047, US2003/0236358, US2003/0204028, US2003/0204027 and US 2003/0191210. The disclosures of these documents are incorporated herein by reference.

As noted above, many biodegradable and/or compostable resins and products are known and commercially available. Examples include products made from 100% sugar cane fiber (bagasse), products made from corn plastic (which is polylactide or "PLA"), and products made from potato starch and/or corn starch. Specific commercially available articles include the disposable items available from Earth Shell corporation of Lutherville, Md.

The NatureFlex, a compostable food and beverage container system currently introduced by New Ice, Inc. of Durango, Colorado, and a packaging film commercially available from Innovia FilmsofMerelbeke, Belgium^TMIs described.

As noted above, any of these materials may be used to form the substrate of the food packaging film of the present invention. In some embodiments of the invention, combinations of two or more of these materials may also be used for this purpose. For example, blends of two or more of these materials can be used to form monolayer films, or even multilayer films. More typically, however, the substrate of the food packaging film of the present invention will be a multilayer film composed of two or more layers of the above materials bonded together by any known technique, such as coextrusion, lamination with or without adhesives, coating, and the like. For example, any of the multi-layer products described in the background section of the present disclosure, particularly co-extruded polyethylene/polypropylene laminated to polyethylene terephthalate (PET) ("co-extrusion"), PET laminated to LDPE (low density polyethylene) and metallized PET laminated to "co-extrusion", can be used for this purpose.

In those embodiments of the invention in which the printed image is located on the inner major face of the substrate, the substrate will typically be formed from an image-transparent film. As used herein, "image transparent" refers to a sufficiently translucent film such that an image printed on the inner major surface of the film is discernible when viewed through the outer (or other) major surface of the film. In other words, the image can be seen through the film. It will therefore be understood that an image transparent flexible film substrate may be made not only from a transparent material, but also from a translucent material, provided that the film substrate is sufficiently thin so that the image printed on its inner major face is discernable when viewed through its outer major face.

The thickness of the flexible film substrate of the food packaging film of the present invention is not critical and essentially any thickness can be used. However, the film substrate should be thin enough so that the food packaging film of the present invention made therefrom remains flexible enough to be wrapped as a food package and thick enough to provide the necessary structural integrity and barrier properties intended for the application. In this context, "package wrap" is understood to mean a film of material similar in flexibility to conventional aluminum foil and/or plastic packaging in the sense that it can be provided in long continuous form as a rolled sheet upon itself, and then unwound from the roll and readily used for hand wrapping of different food products. Thus, a "packaging wrap" is understood to include, for example, plastic bags and other relatively pliable plastic packaging materials, but to exclude more rigid materials, for example, although the walls of a foamed polyethylene cup may be considered "flexible", it is not considered a "packaging wrap" in the context of the present disclosure because it is not flexible enough to be rolled upon itself or easily folded upon itself during manual wrapping of various food articles.

Typically, this means that the flexible film substrate will be at least about 1 micron thick. A minimum thickness of at least about 10 microns, at least about 50 microns, or even at least about 100 microns, or even at least about 150 microns is more interesting. In terms of maximum thickness, this typically means that the flexible film substrate will be no greater than about 5,000 microns. Of greater interest is a maximum thickness of no greater than about 1,000 microns, no greater than about 500 microns, or even no greater than about 250 microns.

As will be appreciated by those skilled in the art, the minimum, maximum and required thickness will depend, at least in part, on the particular material from which the flexible film substrate is made and its intended use, and can be readily determined by routine experimentation.

Printing images

As indicated above, the printed image of the food packaging film of the present invention may be applied to each of the two major faces of the substrate of the film, i.e. its inner major face or its outer major face. Furthermore, the same or different printed images may be applied to both major faces of the substrate, if desired. For this purpose, any known printing technique may be used, including gravure printing, ink jet printing, screen printing, flexographic printing, offset printing, electrophotographic printing, gravure printing, pad printing, letterpress printing, and the like.

Any previously used or later-available ink for printing images on flexible food packaging film may also be used to form the printed images of the food packaging film of the present invention. A particular advantage of the present invention is that the shellac and like barrier coating provided by the present invention effectively prevents contact between the ink and the food product to be packaged. As a result, printing inks that are not suitable for food contact, as well as those suitable for food-grade contact, can be used in the present invention because these barrier coatings effectively separate the used ink from the food to be wrapped.

Examples of suitable printing inks for use in the present invention include solvent-based inks, such as nitrocellulose-modified inks, polyurethane inks, polyvinyl chloride-based inks, polyamide-based inks, and polyvinyl butyral-based inks; water-based inks such as acrylic polymer-based inks, rosin maleic polymer-based inks, protein-based inks, and acrylic modified inks; and 100% solids inks such as Ultraviolet (UV) curable acrylate inks, ultraviolet curable cationic inks, Electron Beam (EB) curable inks, and non-acrylate UV curable inks.

These printing inks can be used to form any type of printed image on one or both major faces of the flexible substrate film of the flexible food packaging film of the present invention. For example, completely fanciful designs and artwork may be printed, providing useful information as an image and/or logo of a tin, such as a picture, size, volume, quality of the packaged food item and/or a trademark of the packaged food item, and the like. Of course, the printed image intended to be printed on the inner major surface of the substrate needs to be the reverse of the image viewed by the reader, as it will be viewed through the outside of the substrate.

Barrier coatings

According to the present invention, the printed image on one major face of the film substrate of the flexible food packaging film of the present invention is coated with a barrier coating made from shellac or other similar material. Since such films can be easily applied by simple coating techniques, the inconvenience and expense associated with extrusion coating and electron beam coating techniques can be completely avoided. In addition, because shellac and its analogs do not substantially react with printing inks (and solvents) typically used to print flexible food packaging films, the hassles and costs associated with adhesive lamination techniques can also be avoided. At the same time, shellac and its analogs exhibit excellent barrier properties that can be used to complement the barrier properties of the flexible film substrates to which they are applied. The overall result is that flexible food packaging films exhibiting excellent barrier properties can be produced very simply and inexpensively.

Shellac coatings have been used as food preservatives for many years. For example, apples and other fruits, both in whole and in part, are often coated with shellac to prevent degradation from moisture and atmospheric oxygen. According to the present invention, the use of shellac or the like as a barrier coating on the printed image formed on the major face of the substrate of the flexible food packaging film of the present invention not only protects the packaged food product from contact with the printing ink making the image, but also improves the barrier properties of the food packaging film of the present invention as a whole.

Shellac is a natural thermoplastic material obtained from the secretions of female shellac. It shows a remarkable combination of properties including oxygen, water vapor, CO, making it an ideal food packaging material₂Low permeability to ethylene and various odors, low lipid solubility, excellent color and excellent clarity. It is also food compatible, has a very low odor, and imparts no flavor, odor or taste to the packaged food.

Shellac is commercially available in four different grades, orange shellac, dewaxed orange shellac, conventional bleached shellac ("waxy white shellac" in europe) and refined bleached shellac. Any grade of shellac may be used in the practice of the present invention. Dewaxed orange shellac is preferred, while refined bleached shellac is even more preferred.

Instead of shellac and/or shellac, any other film-forming material of organic origin, water vapour impermeable and food compatible can also be used. By "organic source" is meant herein a material of animal or vegetable origin other than materials derived from coal, oil, natural gas, tar sands or similar hydrocarbon-containing materials. Further, "food compatible" means that the material is suitable for contact with food and/or beverages as determined by the federal regulation of the united states code. Further, "water vapor impermeable" means that the material has a resistance to water vapor permeability at room temperature of at least 50% of the refined bleached shellac. In some embodiments of the invention, the analogues of shellac will have at least 75%, 85% or even 95% of the room temperature water vapor permeation resistance of the refined bleached shellac, while in other embodiments the analogues of shellac will have room temperature water vapor permeation resistance as good as the refined bleached shellac.

Preferably, these film-forming shellac analogs also have low oxygen permeability. By "low oxygen permeability" is meant that the oxygen permeability of the material is at least 50% of the refined bleached shellac, as measured by the time it takes for the notched flesh of the cut apple portion coated with the material to exhibit a significant brown color by oxidation. Preferred shellac analogs have an oxygen permeability of at least 75% or even 85%, 95% or 100% of the refined bleached shellac.

It is also desirable that these shellac analogs are lipid insoluble. As this may prevent the packaging material film of the present invention from losing its transparency when in contact with a lipid or other organic liquid. By "lipid insoluble" is meant that after 24 hours at room temperature a 1 gram sample of the material dissolves less than twice as much in the rapeseed oil as in the refined bleached shellac. Shellac analogues are more interesting with a solubility in rapeseed oil that is 1.5 times lower than that of the refined bleached shellac, while those with a solubility in rapeseed oil that is lower than that of the refined bleached shellac are even more interesting.

Any organic-derived, food compatible, water vapor impermeable film-forming material that exhibits the above-described properties can be used as the shellac analog of the present invention. Thus, suitable shellac analogs may be selected from certain polysaccharides including cellulose and its derivatives such as hydroxyethyl cellulose (HEC), ethyl cellulose and microcrystalline cellulose. Suitable shellac analogs may also be selected from lipids and resins, including waxes and oils such as paraffin, carnauba, beeswax, candelilla and polyethylene waxes; fatty acids and monoglycerides such as stearyl alcohol, stearic acid, palmitic acid, mono-and diglycerides; natural resins such as wood resins; and coumarone-indene. Suitable shellac analogs may also be selected from proteins including zein (a-zein, b-zein, and/or v-zein), gluten, soy protein, peanut protein, keratin, collagen, gelatin, milk protein (casein), and whey protein. In addition, protective coatings described in U.S. published patent application US2007/02922643, the entire disclosure of which is incorporated herein by reference, may also be used. Examples include chitosan-NaOH, ethyl cellulose, curdlan, deacetylated konjac, Michelman2200R、6661B, etc. Mixtures of these materials may also be used.

The properties exhibited by films made from shellac analogs depend not only on the material itself including such features as molecular weight and purity, but also on other parameters such as any other materials that may also be present, coating thickness and the manner in which the film is applied. Accordingly, care should be taken to select the particular materials used as shellac analogs, to select those materials and/or combinations of materials that will achieve the level of water vapor impermeability and other properties that require consideration of these variables. Based on these considerations, one of ordinary skill in the art should have no difficulty in selecting a particular film-forming material for a particular application.

In addition to these natural film formers, the barrier coatings of the present invention may be formulated with other additional ingredients. For example, these barrier coatings may include film-forming materials of organic origin that exhibit the water vapor resistance properties described above. Examples include certain types of polysaccharides such as carboxymethyl cellulose (CMC), Methyl Cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropyl methyl cellulose (HPMC); starches and their derivatives such as raw starch, modified starch, pregelatinized starch, dextrin, maltodextrin, corn syrup sucrose, glucose/fructose, and sugar polyols; extruded gums (extrudategum) such as gum arabic, gum ghatti, gum karaya and gum tragacanth; seed gums such as guar gum and locust bean gum; microbial fermentation gums such as xanthan gum, gellan gum (gallangum) and chitosan (chilosan); seaweed extracts such as agar, alginate, carageenan and furcellaran; and pectin.

Still further ingredients that may be included in the barrier coatings of the present invention include plasticizers, detackifiers, and colorants. Examples of suitable plasticizers include glycols, such as polyethylene glycol (PEG), polypropylene glycol (PPG), and the like, lipids, such as vegetable oils, mineral oils, medium chain triglycerides, fats, fatty acids, waxes, and the like. Examples of suitable detackifiers include proteins such as zein and the like, and lipidoids such as acetylated monoglycerides, medium chain triglycerides, oils, waxes, fatty acids such as stearic and oleic acids and the like. Examples of suitable colorants include pigments such as organic and inorganic pigments, dyes, and other natural colorants.

The barrier coating of the present invention can be applied to the flexible substrate film by any conventional technique. Typically, the ingredients forming the protective coating of the present invention will be combined with a suitable liquid carrier to form a liquid coating composition, and the composition so formed is then applied to the flexible film substrate by any suitable method, such as by brushing, spraying, dipping, and the like. Examples of suitable liquid carriers include water, various alcohols such as methanol, ethanol, isopropanol, and the like, various ketones such as acetone, methyl ethyl ketone, and the like, various glycols such as propylene glycol, and the like, various glycol ethers, various esters such as ethyl acetate, and the like. The use of carrier liquids based on organic solvents has the particular advantage that the application speed is generally high, since organic solvents evaporate more rapidly than water. On the other hand, the use of a water-based carrier liquid has the particular advantage that the emission of organic-based solvents into the atmosphere is largely eliminated.

The thickness of the barrier coating of the present invention can vary widely, and essentially any thickness that will provide the desired degree of protection can be used. In general, it is contemplated that the minimum thickness is at least about 0.1 microns, more typically at least about 1 micron, or even at least about 5 microns, and the maximum thickness is no greater than about 100 microns, more typically no greater than about 50 microns, or even no greater than about 10 microns. Typically, the coating compositions used to form the barrier coatings of the present invention will be formulated such that they can be applied in a single application, although multiple applications may be used, if desired. In this regard, a particular advantage of using multiple applications is that it eliminates or at least substantially reduces the adverse effects of defects and/or pinholes that may form in the barrier coating if only one application is used.

The composition ratio in the barrier coatings of the present invention can also vary widely, and essentially any amount can be used. Typically, these coatings will contain at least about 50 wt.% shellac or the like, based on the combined weight of the protective coating, i.e., excluding any liquid carrier used to apply the coating. More typically, these protective coatings will contain about 65, 75, 85, or even 95 wt.% or more shellac or the like.

Similarly, the barrier coatings of the present invention may also contain up to about 40 wt.% co-film former (i.e., excluding any liquid carrier) on the same basis, although amounts of co-film former up to about 30 wt.%, 20 wt.%, or even 10 wt.% are more common. If used, the co-film former will typically be present in an amount sufficient to achieve a significant change in barrier coating properties, typically at least about 0.5 wt.%, 1 wt.%, 2 wt.%, or even 5 wt.%, on the same basis.

The barrier coatings of the present invention may also contain, on the same basis, from about 0 to 50 wt.% debonder, although debonder concentrations > 0 to 40 wt.%, from about 3 to 35 wt.%, or even from about 5 to 35 wt.% are more typical, at least when shellac is selected as the primary film-forming resin. Similarly, the barrier coatings of the present invention may also contain, on the same basis, from about 0 to 50 wt.% plasticizer, although plasticizer concentrations > 0 to 40 wt.%, from about 3 to 35 wt.%, or even from about 5 to 35 wt.% are more typical.

The barrier coatings of the present invention may be clear or colored. If colored, the amount of colorant used should be sufficient to form the desired color. In this regard, a particularly interesting feature of the present invention is that the barrier coatings of the present invention can be provided in a contrasting color relative to the printed image formed on the substrate coating. As used herein, "contrasting color" refers to a pigment that makes an image printed on a flexible substrate film more readily visible than an otherwise identical barrier film without the use of a colorant. Thus, the colorant concentration is about 0.1 to 3 wt.%, more typically about 0.3 to 2 wt.%, or even 0.4 to 1 wt.%, considering 10-30 wt.% for very light colors or pastel colors and 40-60 wt.% for organic pigments such as titanium dioxide.

In addition to the above ingredients, the barrier coatings of the present invention may be provided with other materials for providing the desired functional characteristics. For example, the barrier coating may be combined with materials that provide heat resistance to the coating, a desired coefficient of friction, blocking resistance, wrinkle resistance, gloss or matte appearance, antibacterial or antifungal properties, brand protection materials, interesting optical effects such as those derived from pearlescent or light interference pigments, metallic pigments, fragrances including those that may be released over time or when the capsules are broken into encapsulated materials, and the like.

The concentration of the liquid carrier that forms the coating composition used to form the barrier coating of the present invention can also vary widely, and essentially any amount can be used. Concentrations of the liquid carrier of about 20 to 90 wt.% or more based on the total weight of the entire coating composition are possible, although concentrations of 40 to 85 wt.%, 55 to 75 wt.% are more typical.

According to another embodiment of the invention, the barrier coatings of the present invention are applied in a pattern, i.e., they are applied in a predetermined pattern over less than the entire surface area of the inner major face of the flexible film substrate thereafter. Using this method, suitable barriers can be provided in selected areas of the food packaging film of the present invention, such as those areas where greater protection against contact between the printed ink and the packaged food product is necessary. Additionally or alternatively, the barrier coating can be made a different color than both the flexible film substrate and the image printed thereon, such that the barrier coating creates its own complementary graphic, thereby creating a multiple image/graphic design with the printing ink.

It is a particular advantage of the present invention that shellac or other similar organic materials are derived from renewable and sustainable resources, at least when these materials are used to form barrier coatings. In addition, if the flexible film substrate used to form the packaging material of the present invention is biodegradable, a further benefit of the present invention is that the entire packaging film is biodegradable, which is an important advantage when the packaging film of the present invention is disposed of through a landfill.

Another advantage of the present invention is that the barrier coating of the present invention, at least when formed from shellac, can be easily removed by dissolving in an alcohol or other similar solvent. This is particularly advantageous in those situations where it is desirable to recycle the packaging material of the present invention to recycle and reuse the material from which the flexible film substrate is made.

With this consideration, many laminates cannot be effectively recycled or disposed of outside of landfills because they contain incompatible materials. For example, laminates composed of paper and LDPE do not biodegrade and are therefore not compostable. LDPE or paper layers cannot be separately recovered and recycled either, as they are an integral part of the laminate. Similarly, PET/Al-foil/LDPE laminates cannot be recycled and can only be disposed of in landfills, as all of its layers are not biodegradable and cannot be separated from each other.

This problem is avoided by the packaging material film of the invention, since its barrier coating can be easily removed by establishing de-inking methods, such as water washing or flotation de-inking methods for de-inking and recycling of printed paper. In addition, since the barrier coating of the packaging film of the present invention is made from an organic-derived, food-compatible film-forming material, it can be used directly as a raw material for a polymer recycling process that produces thermoformable polymer pellets from low-grade recycled polymer. Such low grade recycled polymers are useful in the preparation of a wide variety of articles, such as yard furniture, by molding thermoplastic polymer pellets produced from these recycled polymers. Laminate structures formed from metal foils and/or thermosetting plastics are not suitable for this purpose because these materials cannot be recycled or thermoformed. This problem is avoided by the packaging film of the present invention, at least when its flexible film substrate is made of a thermoplastic material, because the combined material made by combining its substrate and coating together is still thermoformable.

Examples

The following table illustrates hypothetical coating compositions that can be used to form a barrier coating according to the present invention:

TABLE 1

For providing alkaline water-insolubility, lipid insolubility,

Coating composition for oxygen impermeable barrier coatings

TABLE 2

Coating compositions for providing plasticized and de-tackified water-insoluble, lipid-insoluble, oxygen-impermeable barrier coatings

While a few embodiments of the present invention have been described above, it should be understood that many changes can be made without departing from the spirit and scope of the invention. All such modifications are intended to be included within the scope of this invention, which is defined only by the following claims.

Claims (28)

1. A food packaging film of sufficient flexibility to be provided in the form of a long continuous self-rolled sheet and then unwound from the roll for manually wrapping various food products, the food packaging film comprising a flexible film substrate made of a material exhibiting better resistance to oxygen and water vapor permeability than paper, a natural film-forming resin selected from at least one of synthetic resins, metal foils, and being degradable or biodegradable, the flexible film substrate having a pair of opposed major faces, a printed image on at least one of the major faces, and a barrier coating overlying the printed image, the barrier coating comprising a water vapor impermeable and organic source and a food compatible film-forming material having a resistance to room temperature water vapor permeability of at least 50% refined bleached shellac and a refined bleached shellac to food compatible film-forming material as measured by the time it takes to oxidize a nick of a cut apple portion coated with the material to exhibit a significant brown color by oxidation Less than 50% of the total oxygen permeability resistance.

2. The food packaging film of claim 1, wherein the substrate is formed of a synthetic resin, a natural resin, a metal, or a combination thereof.

3. The food packaging film of claim 2, wherein the barrier coating comprises shellac.

4. The food packaging film of claim 3, wherein the barrier coating comprises at least one of dewaxed orange shellac and refined bleached shellac.

5. The food packaging film of claim 3, wherein the barrier coating comprises a co-film forming agent.

6. The food packaging film of claim 3, wherein the substrate is a multilayer article, and further wherein at least two layers of the multilayer article are different from each other.

7. The food packaging film of claim 2, wherein the substrate is formed of a synthetic resin, a natural resin, or a combination thereof.

8. The food packaging film of claim 7, wherein the barrier coating comprises shellac.

9. The food packaging film of claim 8, wherein the barrier coating comprises at least one of dewaxed orange shellac and refined bleached shellac.

10. The food packaging film of claim 8, wherein the barrier coating comprises a co-film forming agent.

11. The food packaging film of claim 8, wherein the substrate is a multilayer article, and further wherein at least two layers of the multilayer article are different from each other.

12. The food packaging film of claim 1, wherein the barrier coating has a resistance to permeation by water vapor at room temperature of at least 75% of refined bleached shellac and the barrier coating has a resistance to permeation by oxygen of at least 75% of refined bleached shellac.

13. The food packaging film of claim 1, wherein the barrier coating is lipid insoluble.

14. The food packaging film of claim 13, wherein the barrier coating has a resistance to permeation by water vapor at room temperature of at least 75% of refined bleached shellac and the barrier coating has a resistance to permeation by oxygen of at least 75% of refined bleached shellac.

15. The food packaging film of claim 1, wherein the flexible film substrate is biodegradable, and further wherein the barrier coating comprises shellac.

16. The food packaging film of claim 15, wherein the biodegradable flexible film substrate is compostable.

17. The food packaging film of claim 16, wherein the flexible film substrate is a multilayer film composed of at least two layers of different materials.

18. The food packaging film of claim 1, wherein the flexible film substrate is made from a multilayer film of two or more synthetic resins.

19. The food packaging film of claim 18, wherein the flexible film substrate is made of coextruded polyethylene/polypropylene laminated to polyethylene terephthalate, polyethylene terephthalate laminated to low density polyethylene, or metallized polyethylene terephthalate laminated to coextruded polyethylene/polypropylene.

20. The food packaging film of claim 18, wherein the flexible film substrate is made from a multilayer film formed from at least two of nylon, metal foil, and ethylene vinyl acetate polymers and copolymers.

21. The food packaging film of claim 1, wherein the flexible film substrate is made of a natural film-forming resin that is at least one of degradable and biodegradable.

22. The food packaging film of claim 21, wherein the barrier coating comprises at least one of dewaxed orange shellac and refined bleached shellac.

23. The food packaging film of claim 21, wherein the biodegradable flexible film substrate is compostable.

24. A composition comprising a food or pharmaceutical product and a package completely enclosing said food or pharmaceutical product, wherein said package comprises the food packaging film of claim 1.

25. The composition of claim 24, wherein the barrier coating comprises shellac.

26. The composition of claim 25, wherein the barrier coating comprises at least one of dewaxed orange shellac and refined bleached shellac.

27. The composition of claim 25, wherein the flexible film substrate is biodegradable.

28. The composition of claim 25, wherein the flexible film substrate is compostable.