Foamed Film Packaging

Abstract

A package includes at least one layer of foamed thin film having gaseous bubbles, void volumes, or cells. The foamed thin film includes a bio-based content of between about 10% and about 100%, a caliper of between about 10 and 250 microns, and a density reduction of between about a 5% to 50%, as compared to a non-foamed thin film of substantially the same caliper that does not comprise gaseous bubbles, void volumes, or cells.

Description

FIELD OF THE INVENTION

This application relates to the field of packages comprising a foamed film layer, and more specifically, to the field of packages that comprise a foamed film layer made at least in part of renewable, recyclable and/or biodegradable materials.

BACKGROUND OF THE INVENTION

Polyolefin-based plastic film is used to construct a wide variety of packages such as bags, pouches, labels and wraps that hold consumer goods. For example, bags holding stacks of disposable diapers or hygiene articles, pouches for wet wipes, and bags containing granular laundry detergent are often made from plastic film. The plastic film that forms a package may be a single layer of film (called a monofilm), or a combination of layers that can be co-extruded, fabricated as a laminate of separately produced layers that are adhered to one another, or fabricated as an extrusion lamination whereas one layer is extruded onto another previously formed layer(s).

The specific compositions of the film or films that make up the package are selected for a variety of characteristics including liquid or gas permeability, appearance and strength. Another relevant characteristic of plastic film used for packaging is opacity. The level of opacity of the plastic film used in a package impacts the appearance of the package by controlling the extent to which the package's contents are visible through the package. In some circumstances, a higher opacity film may be desirable to protect the contents from exposure to light. Additives such as titanium oxide or other white or colored pigments are mixed with the resin for the purpose of increasing the opacity of a film. In general, decreasing the amount of resin in a film by making the film thinner will in turn reduce its opacity.

Many plastic film packages include opening features, such as, for example, lines of weakness and/or peelable labels covering die cut openings. These lines of weakness and/or peelable labels covering die cut openings are configured to provide convenient consumer access to the contents of the package while maintaining the integrity of the unopened package during shipment and storage. Lines of weakness, such as perforations or scores, provide a mechanism by which the consumer can, in a controlled manner, tear open a package along a predetermined opening trajectory. The label and die cut dispensing opening combination may be configured to provide a re-sealable package for items that require retention of moisture and/or other product ingredients within the package and/or items for which it is desirable to exclude contamination. The die cut defines the dispensing opening through which items are dispensed. The label is sized to overlap the perimeter of the die cut dispensing opening. The label tears the die cut from the package the first time the label is peeled from the package. The label may be capable of completely re-covering and re-sealing the dispensing opening formed by the die cut.

Much of the cost associated with such plastic film packages is the cost of the plastic resin that is used to make the film. Because the amount of plastic resin in the film is directly related to the caliper (or thickness) of the film, efforts to reduce cost in plastic film packages typically involve using a lower caliper film that can still provide the necessary characteristics for a particular package. Because lower caliper film is typically weaker in terms of inherent film tear strength, changing to a lower caliper film in packages that includes an opening feature (e.g., lines of weakness or die cut dispensing openings) requires a redesign of the opening feature to compensate for the lower tear strength of the film. For example, the cuts in a line of perforations may be made shorter to leave more film intact between the cuts to resist unintentional tearing of the line of perforations. Scores in the film may be made shallower to provide additional strength to resist unintentional tearing of a lower caliper film. Film connections between the cuts that define a die cut may be made longer to resist unintentional separation of the die cut from the film. The redesign of the opening feature is costly in terms of engineering and evaluation time. In addition, the redesign of the opening feature typically requires laborious adjustments of various manufacturing components and processes that create the opening feature on the film and possibly the purchase of new tooling as well.

Recent technological developments have made it feasible to produce foamed polyolefin film of suitable thickness (from about 10 microns to about 250 microns) and strength for the types of packages described above. Several exemplary foamed polyolefin films that are suitable for packages are described in European Patent No. 1 646 677. The use of foamed thin film allows for replacement of part of the resin (e.g., from about 5% to about 50% by weight) with gaseous bubbles that are formed or incorporated in the film during a foaming process. Because the voids or cells left by the bubbles occupy volume that was formerly filled with resin, foamed film allows for a reduction in resin without a corresponding reduction in film caliper. One notable feature of foamed thin films is that they have a rough surface texture as compared to a non-foamed film of substantially the same caliper.

Most of the materials used in fabrication of consumer packaging applications are derived from non-renewable resources, such as petroleum. Often, the components of consumer packages are made from polyolefins, such as polyethylene, polypropylene, and polyethylene terephthalate. These polymers are derived from monomers, such as ethylene, propylene, and terephalic acid, which are typically obtained directly from petroleum, coal and/or natural gas via cracking and refining processes. The price and availability of the petroleum/coal/natural gas feedstock therefore has a significant impact on the price of consumer packages which utilize materials derived from petroleum. As the worldwide price of petroleum escalates, so does the price of polyolefin based packaging. Moreover, many consumers display an aversion to purchasing products that are packaged in materials derived from petrochemicals. Other consumers may have adverse perceptions about products derived from petrochemicals being “unnatural” or not environmentally friendly.

Accordingly, it is of continued interest to provide consumer packages which comprise at least one polymer that is at least partially derived from renewable or recycled resources, where the at least one polymer has specific performance characteristics making the polymer particularly useful in consumer packaging. It may also be desirable to provide renewable and/or recyclable packaging that is also biodegradable.

SUMMARY OF THE INVENTION

In one aspect, a package includes at least one layer of foamed thin film having gaseous bubbles, void volumes, or cells. The foamed thin film includes a bio-based content of between about 10% and about 100%, a caliper of between about 10 and 250 microns, and a density reduction of between about a 5% to 50%, as compared to a non-foamed thin film of substantially the same caliper that does not comprise gaseous bubbles, void volumes, or cells.

In one aspect, a package includes at least one layer of foamed thin film having gaseous bubbles, void volumes, or cells. The foamed thin film includes a bio-based content of between about 10% and about 100%, a caliper of between about 10 and 250 microns, a whitening additive, and a density reduction of between about a 5% to 50%, as compared to a non-foamed thin film of substantially the same caliper that does not comprise gaseous bubbles, void volumes, or cells. The whitening additive is selected to produce a foamed thin film having an opacity value of between about 35-99%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is cross section view of a prior art thin film that can be used to construct thin film packages with an opening feature.

FIG. 1b is a cross section view of a foamed thin film that can be used to construct foamed thin film packages with an opening feature in accordance with one or more embodiments of the present invention.

FIG. 2a is a cross section view of a prior art thin film co-extrusion that can be used to construct packages with an opening feature.

FIG. 2b is a cross section view of a foamed thin film co-extrusion that can be used to construct packages with an opening feature in accordance with one or more embodiments of the present invention.

FIG. 3a is a cross section view of a prior art thin film laminate that can be used construct packages with an opening feature.

FIG. 3b is a cross section view of a foamed thin film laminate that can be used to construct packages with an opening feature in accordance with one or more embodiments of the present invention.

FIGS. 4a and 4b are perspective views of a package with a line of weakness constructed in accordance with one or more embodiments of the present invention.

FIG. 5 is a top plan view of a package with a label and die cut dispensing opening constructed in accordance with the present invention.

FIG. 6 is an exploded fragmentary cross section view of the package of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the following terms have the following meanings:

“Agricultural product” refers to a renewable resource resulting from the cultivation of land (e.g., a crop) or the husbandry of animals (including fish).

“Bio-based content” refers to the amount of carbon from a renewable resource in a material as a percent of the mass of the total organic carbon in the material, as determined by ASTM D6866-10, Method B. Note that any carbon from inorganic sources such as calcium carbonate is not included in determining the bio-based content of the material.

“Biodegradation” refers to a process of chemical dissolution of materials by microorganisms or other biological means.

“Bio-identical polymer” refers to polymers that are made from monomers where at least one monomer is derived from renewable resources. For instance, a bio-identical polyolefin is made from olefins that are derived from renewable resources, whereas a petro-based polyolefin is made from olefins typically derived from non renewable oil or gas.

“Bio-new polymer” refers to polymers that are directly derived (i.e., no intermediate compound in the derivation process) from renewable resources. Such renewable resources include cellulose (e.g. pulp fibers), starch, chitin, polypeptides, poly(lactic acid), polyhydroxyalkanoates, and the like.

“Microorganism” is defined as an organism that is too small to see with the naked eye, such as bacteria, fungi, archaea, and protists.

“Monomeric compound” refers to an intermediate compound that may be polymerized to yield a polymer.

“Petrochemical” refers to an organic compound derived from petroleum, natural gas, or coal.

“Petroleum” refers to crude oil and its components of paraffinic, cycloparaffinic, and aromatic hydrocarbons. Crude oil may be obtained from tar sands, bitumen fields, and oil shale.

“Polymer” refers to a macromolecule comprising repeat units where the macromolecule has a molecular weight of at least 1000 Daltons. The polymer may be a homopolymer, copolymer, terpolymer, etc. The polymer may be produced via fee-radical, condensation, anionic, cationic, Ziegler-Natta, metallocene, or ring-opening mechanisms. The polymer may be linear, branched and/or cross-linked.

“Polyethylene” and “polypropylene” refer to polymers prepared from ethylene and propylene, respectively. The polymer may be a homopolymer, or may contain up to about 10 mol % of repeat units from a co-monomer.

“Polymers derived directly from renewable resources” refer to polymers obtained from a renewable resource without intermediates. Typically, these types of polymers would tend be “bio-new”.

“Post-consumer recycled polymers” refer to synthetic polymers recovered after consumer usage and includes recycled polymers from plastic bottles (e.g., laundry, milk, and soda bottles).

“Renewable resource” refers to a natural resource that can be replenished within a 100 year time frame. The resource may be replenished naturally, or via agricultural techniques. Renewable resources include plants, animals, fish, bugs, insects, bacteria, fungi, and forestry products. They may be naturally occurring, hybrids, or genetically engineered organisms. Natural resources such as crude oil, coal, and peat which take longer than 100 years to form are not considered to be renewable resources.

“Synthetic polymer” refers to a polymer which is produced from at least one monomer by a chemical process. A synthetic polymer is not produced directly by a living organism. Synthetic polymers of the present disclosure can be derived from a renewable resource via an indirect route involving one or more intermediate compounds. Typically, these types of polymers would tend to be “bio-identical”, although not all of them are.

“Thin film” is defined as a film having a caliper that is suitable for use in packages such as bags, pouches, labels and wraps for consumer goods, such as, for example, film calipers from about 10 to about 250 microns. As used herein, the term “foamed thin film” designates a film containing at least one layer having a caliper from about 10 microns to about 250 microns and that comprises gaseous bubbles, void volumes, or cells wherein that the at least one layer exhibits a density reduction of at least about 5% by yield (as determined by ASTM D4321) versus a film of the same thickness that does not comprise gaseous bubbles, void volumes, or cells.

A package and a method of constructing a package that includes at least one layer of foamed thin film which comprise at least one polymer that is at least partially derived from renewable or recycled resources, wherein the package includes an opening feature formed in the at least one layer of foamed thin film, is provided herein. The foamed thin film has a caliper of from about 10 microns to about 250 microns thick. The foamed thin film comprises from about 5% to about 50% density reduction as compared to a non-foamed thin film of substantially the same composition and caliper.

The opening feature may include a line of weakness. Advantageously, the line of weakness may be of substantially the same configuration as a line of weakness configured for use in a non-foamed thin film of substantially the same composition and caliper. The yield stress value of the at least one layer of foamed thin film with the line of weakness may be at least about 90% of the yield stress value of the foamed thin film without the line of weakness. The opening feature may be, for example, in the form of perforations, scores, or embossments.

Alternatively, the opening feature may include a die cut dispensing opening and a label adhered to the die cut such that the label overlaps an opening defined by the die cut. In this case, the label has adhesive applied to a first side whereby the label is adhered to the die cut and peelably adhered to the foamed thin film about a periphery of the opening. Advantageously, the adhesive may be of substantially the same composition as adhesive configured for use on a non-foamed thin film of substantially the same composition and substantially the same caliper.

The package may comprise a monolayer foamed film, or multiple layers where at least one layer is foamed. A package may include a foamed thin film co-extrusion that includes at least one foamed thin film layer. A package may include a foamed thin film laminate that includes at least one foamed thin film layer. The foamed thin film layer may be, for example, blown, cast, biaxially oriented cast, post film formation process oriented (i.e., stretched, drawn or tentered) in the cross or machine orientated direction, foamed polyethylene or foamed polypropylene.

The opening feature in the foamed thin film may be formed by weakening a selected opening trajectory or path on the foamed thin film by non-contact means (e.g. laser, spark arcs) or mechanically via a blade, punch or pin or by weakening the selected opening trajectory with a deforming profile.

A package may include at least one layer of foamed thin film made of a plastic resin and a whitening or coloring additive that is added to the plastic resin. The resin could be a traditional petro-based polyolefin, or it could be a renewable based polyolefin, or a blend thereof. Alternatively it could be a blend comprising a petro-based or renewable based polyolefin blend mixed with a renewable “bio-new” material that is chemically different to traditional petro-based polyolefins. The film could be comprised of a material or mixture of materials having a total bio-based content of about 10% to about 100% using ASTM D6866-10, method B.

In one embodiment, the package comprises from about 5% to about 99% by weight of a polymer (A). Polymer (A) comprises at least one or possibly more of a low density polyethylene (LDPE), a polar copolymer of polyethylene such as ethylene vinyl acetate (EVA), a linear low density polyethylene (LLDPE), a high density polyethylene homopolymer/high density polyethylene copolymer, a medium density polyethylene, a very low density polyethylene (VLDPE), a plastomer, a polypropylene/copolypropylene/heterophasic polypropylene, polyethylene terephthalate (PET), PLA (e.g., from Natureworks), polyhydroxyalkanoate (PHA), poly(ethylene-2,5-furandicarboxylate) (PEF), cellulose (available from, for example, Innovia), NYLON 11 (i.e., Rilsan® from Arkema), starch (either thermoplastic starch or starch fillers), bio-polyesters, (e.g., those made from bio-glycerol, organic acid, and anhydride, as described in U.S. Patent Application No. 2008/0200591, incorporated herein by reference), polybutylene succinate, polyglycolic acid (PGA), and polyvinyl chloride (PVC). At least one of the constituents of polymer (A) is at least partially derived from a renewable resource. Recycled materials may also be in added. In specific cases, materials that are biodegradable may be utilized. The whitening or coloring additive is selected to produce a foamed thin film having an opacity value of from about 35% to about 99%. The whitening agent is of substantially the same composition and is present in substantially the same amount as would be selected to produce substantially the same light reflectivity in a non-foamed thin film of substantially the same caliper and substantially the same composition. Some of the “bio-new” materials may further contribute to increasing the opacity of the film, as the presence of this additional material within the film structure can lead to additional light reflectivity, due to their typical incompatibility with the polyolefin matrix. In addition to introducing renewable content and opacity (depending on the exact blend), the addition of a “bio-new” material in particular may modify the performance of the “easy open” feature, depending on the exact type and % of “bio-new” content.

Foamed Films

FIG. 1a is a cross section view of a thin film 100 that is used in many packaging applications such as bags, pouches, labels and wraps that hold consumer goods. Thin films 100 used in such packages typically have a caliper (thickness) from about 10 microns to about 250 microns and are made of a polyolefin resin. Many different blends of components are used in the polyolefin and components are selected for a variety of properties such as strength and opacity. Polyethylene (e.g., Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), High Density Polyethylene (HDPE), Medium Density Polyethylene (MDPE), Metallocene Polyethylene (mPE), Ethyl Vinyl Acetate (EVA), cyclic polyolefins, ionomers (Na+ or Zn+), elastomers, plastomers and mixtures thereof) and polypropylene, and blends thereof are two types of materials that are often used to manufacture thin films 100. LLDPE resins could be manufactured with co-monomers that are either butane, hexene or octane. The catalysts used to produce polymers could be Ziegerl-Natta based, Chromium based, metallocene, single site or other type of catalyst. Thin films 100 can be manufactured using blown film, cast film, cast biaxially stretched film and extrusion base processes. A secondary post film formation process could also be applied to films such as Machine Direction Orientation, or other type of stretching in either one or two directions. As can be seen in FIG. 1a, the thin film 100 is made up of a substantially solid layer of resin. The thin film 100 shown in FIG. 1a is called a monofilm because it consists of a single layer of resin.

FIG. 2a is a cross section view of a thin film co-extrusion 200 that includes a top layer 210, a core 220, and a lower layer 230. Many film packages use thin film co-extrusions because the composition of each layer may be selected to contribute a desired quality to the resulting package. To produce a thin film co-extrusion, resins for each layer are co-extruded while molten and cooled together to form a layered thin film co-extrusion. As can be seen in FIG. 2a, the thin film co-extrusion 200 includes layers (e.g., the top layer 220, core layer 220, and lower layer 230) of each type of resin directly adjacent one another. Thin film co-extrusions may include layers that are selected to provide, for example, strength, opacity, print quality, and moisture resistance. As can be seen in FIG. 2a, the thin film co-extrusion 200 includes layers that are made up of substantially solid layers of resin.

FIG. 3a is a cross section view of thin film laminate 300 that includes a top layer 310, a top adhesive layer 315, a core 320, a bottom adhesive layer 325, and a bottom layer 330. Thin film laminates 300 are similar to thin film co-extrusions 200 because both include layers of different resins that are selected to contribute a desired quality to the resulting package. However, rather than being combined in a molten form, the layers of a thin film laminate 300 are separately formed and cooled. Laminates are often used when one or more of the layers is not well suitable for co-extrusion, such as, for example, metalized layers that require significantly different processing techniques as compared to plastic layers. The separate layers (e.g., the top layer 310 the core 320, and the bottom layer 330) are then fixed to one another, such as, for example, using adhesive (e.g., the top adhesive layer 315 and the bottom adhesive layer 325). As can be seen in FIG. 3a, the thin film laminate 300 includes layers that are made up of substantially solid layers of resin.

FIGS. 1b, 2b, and 3b illustrate various foamed thin films 10, 20, 30 that are suitable for use in packaging applications. The foamed thin films 10, 20, 30 each include at least one foamed layer, 12, 23, 32, respectively. As discussed above, until recently, thin films for use in packaging were not believed to be suitable for foaming because of concerns about potential degradations in tear strength that could be brought about by the loss of resin content in a foamed film. EP 1 646 677 provides details about specific resin compositions and processing steps that enable the production of foamed thin films. The resin used in making the foamed film may include renewable materials—either “bio-identical” or “bio-new” materials. Some non-limiting options of applicable bio-identical and/or bio-new materials are further detailed below.

Referring to FIG. 1b, a foamed thin monofilm 10 made up of a resin 12, such as, for example, polyolefin, in which gas bubbles 14 are entrapped is shown. One way to produce foamed monofilm 10 is adding one or more chemical blowing agents such as, for example, Sodium Hydro Carbonate Powder and an acidifier to the master batch of resin 12 prior to heating. Upon heating, chemical blowing agents release carbon dioxide. The carbon dioxide expands and forms bubbles 14 in the monofilm 10 during subsequent processing steps. One exemplary chemical equation describing the transition of the blowing agent to carbon dioxide is:

NaHCO₃(Sodium Hydro Carbonate Powder)+H⁺(Acidifier)→Na⁺+CO₂+H₂O

Some of the carbon dioxide bubbles 14 escape the molten resin 12 while others are trapped in the resin 12 during cooling to form voids that remain after solidification of the resin. An alternative to the use of chemical blowing agents that react in the resin to produce bubbles 14 is to inject a gas such as carbon dioxide or nitrogen into the molten plastic within the extruder prior to it leaving the die, during film manufacture (such as practiced in the Mucell process by the Trexel Corporation). While the bubbles 14 shown in FIG. 1b are generally spherical in the melt and have a diameter from about 1 micron to about 100 microns, other shapes are contemplated. For example, in some solidified foamed films, the bubbles are generally cigar shaped (in cross sectional analysis) and oriented in the direction of film extrusion. In a foamed thin polyethylene monofilm having a caliper of about 40 microns, a typical cigar shaped bubble may be about 10 microns in diameter (typically <20 microns) and typically from about 50 microns to about 300 microns in length. The foam structure of a foamed thin monofilm 10 is generally closed towards the surface such that substantially all of the bubbles 14 close to the surface are closed. Because the bubbles 14 occupy volume that would have been occupied by resin 12 in a non-foamed thin film, the foamed thin monofilm 10 in FIG. 1b uses less resin 12 than its non-foamed counterpart 100 in FIG. 1a while maintaining substantially the same overall thickness “t.” Of course, other foaming methods may be employed in the practice of the present invention, such as, for example, through the incorporation of particles (e.g. CaCO3 or PS) followed by stretching (uni-axial or bi-axial) of the film to cavitate around the particles. We also contemplate that bubbles with smaller dimensions could be formed with a particular selection of materials.

FIG. 2b shows a foamed thin film co-extrusion 20 that includes a foamed core 23 and a non-foamed top layer 25 and a non-foamed bottom layer 27. While only the core 23 is shown as foamed, any combination of layers in a foamed thin film co-extrusion may be foamed, including the top layer 25, the bottom layer 27, or the top layer 25 and the bottom layer 27, or all three layers 23, 25, 27. In addition, the core 23 need not be foamed if any other layer is foamed and any number of foamed and non-foamed layers may be present in the foamed thin film co-extrusion. The use of foamed thin film co-extrusions 20 is well suited for many packaging applications because layers can be selected for tensile strength, sealing properties, cost, and aesthetic impression. It has been observed that in foamed thin film co-extrusions, foaming in one layer is limited to the foamed layer. That is, foaming does not appear to induce foaming in adjacent non-foamed layers.

By way of example, a bag adapted for storing large granules is constructed of a thin film laminate that includes the thin film co-extrusion 200 (FIG. 2a) as a base layer. This particular thin film co-extrusion 200 is configured to present a white outer surface on which a printed top layer (not shown) is applied while creating a blue inner surface that enhances the appearance of the white granules stored in the bag when viewing the granules through the bag's opening. The top layer 210 of the thin film co-extrusion 200 is made of a white polyethylene film having a caliper of approximately 15 microns that is adapted for improved interaction with the printed top layer (not shown). The core 220 is made of a white polyethylene film having a caliper of approximately 40 microns that is adapted to mask the blue color from the bottom layer 230 from showing through. The bottom layer 230 is made of a blue polyethylene film having a caliper of approximately 15 microns that is adapted to present a visually appealing background for the granules in the bag.

The foamed thin film co-extrusion 20 shown in FIG. 2b may be used to replace the thin film co-extrusion 200. The foamed thin film co-extrusion 20 includes a top layer 25 made of an extreme white polyethylene film having a caliper of approximately 15 microns, a core 23 made of a foamed light white polyethylene film having a caliper of approximately 40 microns, and a bottom layer made of a blue polyethylene film having a caliper of approximately 15 microns. The foamed core 23 uses about half as much resin as the non-foamed core (e.g., core 220 in FIG. 2a). To compensate for the change in appearance caused by the presence of bubbles in the core 23, much of the white or colored pigment in the core 23 was removed to reduce the contrast between bubble and resin. The white intensity of the top layer was increased to achieve a comparable appearance between the thin film co-extrusion 200 and the foamed thin film co-extrusion 20. Of course, the development of a foamed thin film co-extrusion to replace an existing thin film co-extrusion may involve changing the caliper of different layers, changing the material composition of different layers, and/or adding or removing layers.

FIG. 3 illustrates a foamed thin film laminate 30 that includes a foamed core 32 and a non-foamed top layer 35 and bottom layer 39. While only the core 32 is shown as foamed, any combination of layers in a foamed thin film laminate may be foamed, including the top layer 35, a bottom layer 39, both top layer 35 and bottom layer 39, or all three layers 32, 35, 39. In addition, the core 32 need not be foamed if any other layer is foamed and any number of foamed and non-foamed layers may be present in the foamed thin film laminate. The use of foamed thin film laminates 30 is well suited for many packaging applications, especially for packages that require a layer that is not readily co-extruded with other layers in the foamed thin film laminate. It is believed that the same types of adhesive (e.g., adhesives 315 and 325) used in non-foamed thin film laminates may be used as adhesives (e.g., adhesives 33, 37) to adhere layers in foamed thin film laminates.

Opening Features

As used herein, the term “opening feature” is defined as an aid to opening of the package that includes a weakening of a selected opening trajectory on the foamed thin film. Two examples of such opening features are linear lines of weakness and die cut dispensing openings with labels.

FIGS. 4a and 4b illustrate a bag 40 that includes walls of foamed thin film 42 and a linear line of weakness 43. The line of weakness 43 is configured to remain intact until opened by the consumer along a linear opening trajectory as shown by the arrows in FIG. 4b. The line of weakness 43 can be formed, for example, from a line of scores that partially cut through the wall 42 of the bag 40 or a line of perforations that completely cut through the wall 42 of the bag 40. The lines of weakness 43 are of substantially the same configuration as lines of weakness that are configured for use in a bag (not shown) having non-foamed thin film walls of substantially the same caliper. The lines of weakness can be produced using methods including scoring and perforation. The scoring or perforation may be performed using a laser or by mechanical means. The methods and method parameters used to produce the line of weakness 43 in a foamed thin wall (e.g., wall 42) are substantially the same as methods used to produce a line of weakness in a non-foamed thin wall of substantially the same caliper.

One method of making a line of weakness uses at least one laser. First a laser beam with sufficient wattage to evaporate a portion of the film material is focused onto the thin film. The use of laser technology allows for very accurate control of the depth of penetration from very slight scoring to complete perforation of the thin film. A laser using any form of electromagnetic radiation can be used. Suitable lasers for making lines of weakness in thin films include those based on CO₂ gas.

Another suitable method for producing the lines of weakness is the use of blades. The blades are installed on a cylinder, which is mounted directly on the film processing machinery so that the cuts are made prior to formation of the bag as the film travels past the blade-equipped cylinder Different blade patterns can be used to get different patterns in the line of weakness. The pressure applied to the blades is also varied during the process to control the dimensions and depth of the cuts to ensure the bag opens easily.

Embossing is another alternative method for production of lines of weakness. The embossing technology weakens the thin film in specific areas by means of pressure, temperature, processing time and a deforming profile. The desired results are achieved by changing the caliper and/or material structure at the embossing trajectory. The basic equipment used for embossing consists of a sealing jaw capable of pressing against a back plate. A deforming profile or pattern is fixed to the jaw and heated. The thin film is pressed between the deforming profile and the back plate. The main variables known to affect this process are: heating temperature, cooling temperature, pressure, heating time, cooling time, film tension while embossing, film tension after embossing, back plate material, back plate thickness, back plate temperature, jaw pattern and jaw thickness. The embossing unit is typically installed after an unwinding station of the thin film and could be incorporated into the packaging production line. EP 1 409 366 describes methods of producing lines of weakness in non-foamed thin films in detail.

Lines of weakness in foamed thin film (e.g., line of weakness 43 in FIGS. 4a and 4b and die cut line of weakness 52 in FIG. 5) may form many different patterns. Those patterns may take the form of a continuous line, a dashed line, or combinations thereof. One exemplary line of weakness is a dashed line 43 that includes a plurality of scored segments 44. The length of each scored segment 44 varies from about 0.12 mm to about 4.4 mm. The distance of the connections or bridges 45 between adjacent scored segments 44 varies from about 0.4 mm to about 4 mm. The score depth may vary depending on the thickness of the foamed thin film. Notably, any pattern that is suitable for use in a non-foamed thin film wall will also be suitable for use in a foamed thin film wall of substantially the same caliper.

Lines of weakness 43, 52 are designed to deteriorate the strength of the foamed thin film in such a way that it can withstand normal filling, packing and handling operation and yet be easily opened by the consumer. This is achieved by reducing the trapezoidal tear strength of the foamed thin film. Reduction of the trapezoidal tear strength is also generally accompanied by loss of tensile strength.

The line of weakness 43, 52 may be characterized using the following test methods: a) ASTM D-882 Standard Test Method for Tensile Properties on Thin Plastic Sheeting and b) ASTM D-5733 Standard Test Method for Tearing Strength of Nonwoven Fabrics by the Trapezoidal Procedure. The line of weakness 43, 52 may be characterized by three parameter values obtained from these standard tests. The first is yield stress value. The yield stress value of the foamed thin film with a line of weakness as measured by ASTM D-882 should be no less than about 90% of the yield stress value of the foamed thin film without a line of weakness. Second, the final or rupture stress value of the foamed thin film with the line of weakness should be no lower than about 90% of the yield stress value of the foamed thin film without the line of weakness. Third, the average trapezoidal tearing force according to ASTM D-5733 of the foamed thin film with the line of weakness should be less than about 4 kilograms of force.

FIG. 5 is a top plan view of a package 48 having at least one foamed thin film wall 49. The package 48 includes a die cut dispensing opening/label combination 50 that enables a user to reseal the package 48 after dispensing items from the package 48. A die cut line of weakness 52, which can be seen through the label 54 in FIG. 5, is formed in the foamed thin film wall 49. The die cut line of weakness 52 may have a significantly larger proportion of weakened foamed film material than the line of weakness 43 in FIGS. 4a and 4b. The die cut line of weakness 52 is shown having four long perforations 52a-52d that are attached by relatively small connections or bridges 52e-52h. The large proportion of weakened foam film material in the die cut line of weakness means that very little force will be required to completely separate a die cut 59 defined by the die cut line of weakness 52 from the foamed thin film wall 49. A label 54 covers and overlaps the die cut 59. The label 54 is adhered to the foamed thin wall 49 with, for example, adhesive (of course other methods of adhesion can be used).

To dispense an item from the package 48, the consumer peels an edge of the label 54 as indicated by the arrow in FIG. 5. In the first use, the label 54 pulls the die cut 59 free from the foamed thin wall 49 by rupturing the bridges 52e-52h. The die cut 59 remains adhered to an underside of the label 54 as shown in FIG. 6. To reseal the package 48, the consumer re-adheres the label 54 to the foamed thin wall 49.

FIG. 6 is an exploded cross section view of the die cut dispensing opening/label combination 50 and the foamed thin wall 49. Adhesive 57 is shown on an underside of the label 54 with an optional adhesive-free region 65 at a lead edge of the label 54 that defines a tab that can be gripped by a consumer. The die cut 59 defines a dispensing opening 67 through which items are dispensed from the package 48. In other embodiments (not shown), regions of different types of adhesive may be present on the underside of the label and the die cut dispensing opening/label combination may include intermediate layers disposed between the package and the label.

The perforations (or scores) 52a-d (FIG. 5) that are used in the die cut line of weakness 52 are produced according to the same methods described above with respect to lines of weakness 43 (FIGS. 4a, 4b). As with the lines of weakness 43, the methods and method parameters used to produce the die cut line of weakness 52 in a foamed thin wall (e.g., wall 49) are substantially the same as methods used to produce a die cut dispensing opening in a non-foamed thin wall of substantially the same caliper. In addition the adhesive that is used on the label 54 in a die cut dispensing opening/label combination (e.g., die cut dispensing opening/label combination 50) used on a foamed thin wall (e.g. the foamed thin wall 49) is substantially the same as adhesive (e.g., the adhesive 57) that is used on a label used with a non-foamed thin wall of substantially the same composition.

Polymers Derived from Renewable & Sustainable Resources

A number of renewable resources contain polymers that are suitable for use in consumer packages (i.e., the polymer is obtained from the renewable resource without intermediates). Suitable extraction and/or purification steps may be necessary, but no intermediate compound is required. Such polymers that are derived directly from renewable resources include cellulose (e.g. pulp fibers), starch, chitin, polypeptides, poly(lactic acid), polyhydroxyalkanoates, and the like. We typically describe such polymers as “bio-new” polymers. These polymers may be subsequently chemically modified to improve end use characteristics (e.g., conversion of cellulose to yield carboxycellulose or conversion of chitin to yield chitosan). However, in such cases, the resulting polymer is a structural analog of the starting polymer. Any polymers derived directly from renewable resources with no intermediate compounds (and their derivatives) that are known in the art may be useful herein. All of these materials are within the scope of the present disclosure.

Synthetic polymers of the present disclosure can be derived from a renewable resource via an indirect route involving one or more intermediate compounds. Suitable intermediate compounds derived from renewable resources include sugars, such as, for example, monosaccharides, disaccharides, trisaccharides, and oligosaccharides. Sugars such as sucrose, glucose, fructose and maltose may be readily produced from renewable resources such as sugar cane and sugar beets. Sugars may also be derived (e.g., via enzymatic cleavage) from other agricultural products such as starch or cellulose. For example, glucose may be prepared on a commercial scale by enzymatic hydrolysis of corn starch. While corn is a renewable resource in North America, other common agricultural crops may be used as the base starch for conversion into glucose. Wheat, buckwheat, arracaha, potato, barley, kudzu, cassava, sorghum, sweet potato, yam, arrowroot, sago, and other similar starchy fruit, seeds, or tubers may also be used in the preparation of glucose.

Other suitable intermediate compounds derived from renewable resources include monofunctional alcohols such as methanol or ethanol and polyfunctional alcohols such as glycerol. Ethanol may be derived from many of the same renewable resources as glucose. For example, cornstarch may be enzymatically hydrolyzed to yield glucose and/or other sugars. The resultant sugars can be converted into ethanol by fermentation. As with glucose production, corn is an ideal renewable resource in North America; however, other crops may be substituted. Methanol may be produced from fermentation of biomass. Glycerol is commonly derived via hydrolysis of triglycerides present in natural fats or oils, which may be obtained from renewable resources such as animals or plants.

Other intermediate compounds derived from renewable resources include organic acids (e.g., citric acid, lactic acid, alginic acid, amino acids etc.), aldehydes (e.g., acetaldehyde), and esters (e.g., cetyl palmitate, methyl stearate, methyl oleate, etc.). Additional intermediate compounds such as methane and carbon monoxide may also be derived from renewable resources by fermentation and/or oxidation processes.

Intermediate compounds derived from renewable resources may be converted into polymers (e.g., glycerol to polyglycerol) or they may be converted into other intermediate compounds in a reaction pathway which ultimately leads to a polymer useful in a consumer package. An intermediate compound may be capable of producing more than one secondary intermediate compound. Similarly, a specific intermediate compound may be derived from a number of different precursors, depending upon the reaction pathways utilized.

Particularly desirable intermediates include olefins. Olefins such as ethylene and propylene may also be derived from renewable resources. For example, methanol derived from fermentation of biomass may be converted to ethylene and or propylene, which are both suitable monomeric compounds, as described in U.S. Pat. Nos. 4,296,266 and 4,083,889. Ethanol derived from fermentation of a renewable resource may be converted into the monomeric compound ethylene via dehydration as described in U.S. Pat. No. 4,423,270. Similarly, propanol or isopropanol derived from a renewable resource can be dehydrated to yield the monomeric compound of propylene as exemplified in U.S. Pat. No. 5,475,183. Propanol is a major constituent of fusel oil, a by-product formed from certain amino acids when potatoes or grains are fermented to produce ethanol.

Charcoal derived from biomass can be used to create syngas (i.e., CO+H₂) from which hydrocarbons such as ethane and propane can be prepared (Fischer-Tropsch Process). Ethane and propane can be dehydrogenated to yield the monomeric compounds of ethylene and propylene.

Other sources of materials to form polymers derived from renewable or sustainable resources include post-consumer recycled materials. Sources of synthetic post-consumer recycled materials can include plastic bottles (e.g., soda bottles), plastic films, plastic packaging materials, plastic bags and other similar materials which contain synthetic materials which can be recovered.

In one aspect, the present disclosure is directed to films having at least one layer of a composition comprising an intimate admixture of a thermoplastic polymer and a wax having a melting point greater than 25° C. The wax can have a melting point that is lower than the melting temperature of the thermoplastic polymer. The wax can be present in the composition in an amount of about 5 wt % to about 40 wt %, about 8 wt % to about 30 wt %, or about 10 wt % to about 20 wt %, based upon the total weight of the composition. The wax can comprise a lipid, which can be selected from the group consisting of a monoglyceride, diglyceride, triglyceride, fatty acid, fatty alcohol, esterified fatty acid, epoxidized lipid, maleated lipid, hydrogenated lipid, alkyd resin derived from a lipid, sucrose polyester, or combinations thereof. The wax can comprise a mineral wax, such as a linear alkane, a branched alkane, or combinations thereof. Specific examples of mineral wax are paraffin and petrolatum. The wax can be selected from the group consisting of hydrogenated soy bean oil, partially hydrogenated soy bean oil, epoxidized soy bean oil, maleated soy bean oil, tristearin, tripalmitin, 1,2-dipalmitoolein, 1,3-dipalmitoolein, 1-palmito-3-stearo-2-olein, 1-palmito-2-stearo-3-olein, 2-palmito-1-stearo-3-olein, 1,2-dipalmitolinolein, 1,2-distearo-olein, 1,3-distearo-olein, trimyristin, trilaurin, capric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and combinations thereof. The wax can be selected from the group consisting of: a hydrogenated plant oil, a partially hydrogenated plant oil, an epoxidized plant oil, a maleated plant oil. Specific examples of such plant oils include soy bean oil, corn oil, canola oil, and palm kernel oil. The wax can be dispersed within the thermoplastic polymer such that the wax has a droplet size of less than 10 μm, less than 5 μm, less than 1 m, or less than 500 nm within the thermoplastic polymer. The wax can be a renewable material.

In one aspect, the present disclosure is directed to films having at least one layer of a composition comprising an intimate admixture of a thermoplastic polymer and about 5 wt % to about 40 wt % of an oil, based upon the total weight of the composition, wherein the oil has a melting point of 25° C. or less and a boiling point greater than 160° C. The oil can comprise a lipid, which can be selected from the group consisting of a monoglyceride, diglyceride, triglyceride, fatty acid, fatty alcohol, esterified fatty acid, epoxidized lipid, maleated lipid, hydrogenated lipid, alkyd resin derived from a lipid, sucrose polyester, or combinations thereof. The oil can comprise a mineral oil, such as a linear alkane, a branched alkane, or combinations thereof. The oil can be selected from the group consisting of soy bean oil, epoxidized soy bean oil, maleated soy bean oil, corn oil, cottonseed oil, canola oil, castor oil, coconut oil, coconut seed oil, corn germ oil, fish oil, linseed oil, olive oil, oiticica oil, palm kernel oil, palm oil, palm seed oil, peanut oil, rapeseed oil, safflower oil, sperm oil, sunflower seed oil, tall oil, tung oil, whale oil, triolein, trilinolein, 1-stearo-dilinolein, 1-palmito-dilinolein, lauroleic acid, linoleic acid, linolenic acid, myristoleic acid, oleic acid, palmitoleic acid, 1,2-diacetopalmitin, and combinations thereof. The oil can be dispersed within the thermoplastic polymer such that the oil has a droplet size of less than 10 μm, less than 5 μm, less than 1 μm, or less than 500 nm within the thermoplastic polymer. The oil can be a renewable material.

In one aspect, the present disclosure is directed to films having at least one layer of a composition comprising an intimate admixture of a thermoplastic starch (TPS), a thermoplastic polymer and an oil, wax, or combination thereof present in an amount of about 5 wt % to about 40 wt %, based upon the total weight of the composition.

Some or all of the above detailed materials may also be bio-degradable.

Exemplary Synthetic Polymers

Olefins derived from renewable resources may be polymerized to yield polyolefins. Such polymers are typically referred to as “bio-identical” polymers. Ethylene and propylene derived from renewable resources may be polymerized under the appropriate conditions to prepare polyethylene and/or polypropylene having desired characteristics for use in consumer packages. The polyethylene and/or polypropylene may be high density, medium density, low density, or linear-low density. Further, polypropylene can include homopolymer-polypropylene or co-polymer polypropylene. Polyethylene and/or polypropylene may be produced via free-radical polymerization techniques, or by using Ziegler-Natta (ZN) catalysis or Metallocene catalysts. Examples of such bio-sourced polyethylenes and polypropylenes are described in U.S. Publication Nos. 2010/0069691, 2010/0069589, 2009/0326293, and 2008/0312485, PCT Application Nos. WO2010063947 and WO2009098267; and European Patent No. 1102569. Other olefins that can be derived from renewable resources include butadiene and isoprene. Examples of such olefins are described in U.S. Publication Nos. 2010/0216958 and 2010/0036173.

Such polyolefins being derived from renewable resources can also be reacted to form various copolymers, including for example, random block copolymers, such as ethylene-propylene random block copolymers (e.g., Borpact™ BC918CF manufactured by Borealis). Such copolymers and methods of forming the same are contemplated and described for example in European Patent No. 2121318. In addition, the polyolefin derived from a renewable resource may be processed according to methods known in the art into a form suitable for the end use of the polymer. The polyolefin may comprise mixtures or blends with other polymers such as polyolefins derived from petrochemicals.

Bio-polyethylene terephthalate is available from Teijin Fibers Ltd. It also can be produced from the polymerization of bio-ethylene glycol with bio-terephthalic acid. Bio-ethylene glycol can be derived from renewable resources via a number of suitable routes, such as, for example, those described in WO/2009/155086 and U.S. Pat. No. 4,536,584, each incorporated herein by reference. Bio-terephthalic acid can be derived from renewable alcohols through renewable p-xylene, as described in WO/2009/079213, which is incorporated herein by reference. In some embodiments, a renewable alcohol (e.g., isobutanol) is dehydrated over an acidic catalyst in a reactor to form isobutylene. The isobutylene is recovered and reacted under the appropriate high heat and pressure conditions in a second reactor containing a catalyst known to aromatize aliphatic hydrocarbons to form renewable p-xylene. In another embodiment, a renewable alcohol (e.g., isobutanol) is dehydrated and dimerized over an acid catalyst. The resulting diisobutylene is recovered and reacted in a second reactor to form renewable p-xylene. In yet another embodiment, a renewable alcohol (e.g., isobutanol) containing up to 15 wt. % water is dehydrated, or dehydrated and oligomerized, and the resulting oligomers are aromatized to form renewable p-xylene. Renewable phthalic acid or phthalate esters can be produced by oxidizing p-xylene over a transition metal catalyst (see, e.g., Ind. Eng. Chem. Res., 39:3958-3997 (2000)), optionally in the presence of one or more alcohols.

Bio-poly(ethylene-2,5-furandicarboxylate), a.k.a., bio-PEF, can be produced according to the route disclosed in Werpy and Petersen, “Top Value Added Chemicals from Biomass. Volume I—Results of Screening for Potential Candidates from Sugars and Synthesis Gas, produced by the Staff at Pacific Northwest National Laboratory (PNNL): National Renewable Energy Laboratory (NREL), Office of Biomass Program (EERE),” 2004 and PCT Application No. WO 2010/077133, which are both incorporated herein by reference.

It should be recognized that any of the aforementioned synthetic polymers (e.g., copolymers) may be formed by using a combination of monomers derived from renewable resources and monomers derived from non-renewable (e.g., petroleum) resources. For example, the copolymer can comprise propylene repeat units derived from a renewable resource and isobutylene repeat units derived from a petroleum source.

In addition to being formed from the synthetic polymers described herein, the consumer packages can further include additional additives. For example, opacifying agents can be added. Such opacifying agents can include iron oxides, carbon black, aluminum, aluminum oxide, titanium dioxide, talc and combinations thereof. These opacifying agents can comprise about 0.1% to about 5% by weight of the packages; and in certain embodiments, the opacifying agents can comprise about 0.3% to about 3% of the packages. It will be appreciated that other suitable opacifying agents may be employed and in various concentrations. Examples of opacifying agents are described in U.S. Pat. No. 6,653,523.

Furthermore, the consumer packages may comprise other additives, such as other polymers (e.g., a polypropylene, a polyethylene, a ethylene vinyl acetate, a polyethylene terephthalate, a polymethylpentene, any combination thereof, or the like—whether derived from a renewable resource or petro-based source), a filler (e.g., glass, talc, calcium carbonate, or the like), a mold release agent, a flame retardant, an electrically conductive agent, an anti-static agent, a pigment (inorganic or organic), an antioxidant, an impact modifier, a stabilizer (e.g., a UV absorber), wetting agents, dyes, or any combination thereof.

Some materials used in the structures described herein may be a blend comprising a petro-based or renewable based “bio-identical” polyolefin blend mixed with a renewable “bio-new” material. Typically the “bio-new” material would be added to the petro-based or renewable based “bio-identical” polyolefin in the range 5-50 wt %, as higher than that would typically be difficult to process. The blend could also contain some recycled materials, typically up to around 50%—higher than that level could typically cause gels to form in the film which act as imperfections.

Validation of Polymers Derived from Renewable Resources

A suitable validation technique is through ¹⁴C analysis. A small amount of the carbon dioxide in the atmosphere is radioactive. ¹⁴C carbon dioxide is created when nitrogen is struck by an ultra-violet light produced neutron, causing the nitrogen to lose a proton and form carbon of molecular weight 14 which is immediately oxidized to carbon dioxide. This radioactive isotope represents a small but measurable fraction of atmospheric carbon. Atmospheric carbon dioxide is cycled by green plants to make organic molecules during photosynthesis. The cycle is completed when the green plants or other forms of life metabolize the organic molecules, thereby producing carbon dioxide which is released back to the atmosphere. Virtually all forms of life on Earth depend on this green plant production of organic molecules to grow and reproduce. Therefore, the ¹⁴C that exists in the atmosphere becomes part of all life forms, and their biological products. In contrast, fossil fuel based carbon does not have the signature radiocarbon ratio of atmospheric carbon dioxide.

Assessment of the renewably based carbon in a material can be performed through standard test methods. Using radiocarbon and isotope ratio mass spectrometry analysis, the bio-based content of materials can be determined. ASTM International, formally known as the American Society for Testing and Materials, has established a standard method for assessing the bio-based content of materials. The ASTM method is designated ASTM D6866-10.

The application of ASTM D6866-10 to derive a “bio-based content” is built on the same concepts as radiocarbon dating, but without use of the age equations. The analysis is performed by deriving a ratio of the amount of organic radiocarbon (¹⁴C) in an unknown sample to that of a modern reference standard. The ratio is reported as a percentage with the units “pMC” (percent modern carbon).

The modern reference standard used in radiocarbon dating is a NIST (National Institute of Standards and Technology) standard with a known radiocarbon content equivalent approximately to the year AD 1950. AD 1950 was chosen since it represented a time prior to thermo-nuclear weapons testing which introduced large amounts of excess radiocarbon into the atmosphere with each explosion (termed “bomb carbon”). The AD 1950 reference represents 100 pMC.

“Bomb carbon” in the atmosphere reached almost twice normal levels in 1963 at the peak of testing and prior to the treaty halting the testing. Its distribution within the atmosphere has been approximated since its appearance, showing values that are greater than 100 pMC for plants and animals living since AD 1950. It's gradually decreased over time with today's value being near 107.5 pMC. This means that a fresh biomass material such as corn could give a radiocarbon signature near 107.5 pMC.

Combining fossil carbon with present day carbon into a material will result in a dilution of the present day pMC content. By presuming 107.5 pMC represents present day biomass materials and 0 pMC represents petroleum derivatives, the measured pMC value for that material will reflect the proportions of the two component types. A material derived 100% from present day soybeans would give a radiocarbon signature near 107.5 pMC. If that material was diluted with 50% petroleum derivatives, for example, it would give a radiocarbon signature near 54 pMC (assuming the petroleum derivatives have the same percentage of carbon as the soybeans).

A biomass content result is derived by assigning 100% equal to 107.5 pMC and 0% equal to 0 pMC. In this regard, a sample measuring 99 pMC will give an equivalent bio-based content value of 92%.

Assessment of the materials described herein was done in accordance with ASTM D6866. The mean values encompass an absolute range of 6% (plus and minus 3% on either side of the bio-based content value) to account for variations in end-component radiocarbon signatures. It is presumed that all materials are present day or fossil in origin and that the desired result is the amount of bio-based component “present” in the material, not the amount of bio-based material “used” in the manufacturing process.

In one embodiment, a mono-layer film comprises a bio-based content value from about 10% to about 100% using ASTM D6866-10, method B. In another embodiment, a mono-layer film comprises a bio-based content value from about 20% to about 100% using ASTM D6866-10, method B. In yet another embodiment, a mono-layer film comprises a bio-based content value from about 50% to about 100% using ASTM D6866-10, method B.

In one embodiment, a multi-layer film comprises a bio-based content value from about 10% to about 100% using ASTM D6866-10, method B. In another embodiment, a multi-layer film comprises a bio-based content value from about 20% to about 100% using ASTM D6866-10, method B. In yet another embodiment, a multi-layer film comprises a bio-based content value from about 50% to about 100% using ASTM D6866-10, method B.

In order to apply the methodology of ASTM D6866-10 to determine the bio-based content of a package, a representative sample of the component must be obtained for testing. In one embodiment, a representative portion of the package can be ground into particulates less than about 20 mesh using known grinding methods (e.g., Wiley® mill), and a representative sample of suitable mass taken from the randomly mixed particles.

Other Materials

The consumer packages disclosed herein can optionally include a colorant masterbatch. As used herein, a “colorant masterbatch” refers to a mixture in which pigments are dispersed at high concentration in a carrier material. The colorant masterbatch is used to impart color to the final product. In some embodiments, the carrier is a bio-based plastic or a petroleum-based plastic, while in alternative embodiments, the carrier is a bio-based oil or a petroleum-based oil. The colorant masterbatch can be derived wholly or partly from a petroleum resource, wholly or partly from a renewable resource, or wholly or partly from a recycled resource. Non-limiting examples of the carrier include bio-derived or oil derived polyethylene (e.g., linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE)), bio-derived oil (e.g., olive oil, rapeseed oil, peanut oil, soybean oil, or hydrogenated plant-derived oils), petroleum-derived oil, recycled oil, bio-derived or petroleum derived polyethylene terephthalate, polypropylene, and a mixture thereof. The pigment of the carrier, which can be derived from either a renewable resource or a non-renewable resource, can include, for example, an inorganic pigment, an organic pigment, a polymeric resin, or a mixture thereof. Non-limiting examples of pigments include titanium dioxide (e.g., rutile, anatase), copper phthalocyanine, antimony oxide, zinc oxide, calcium carbonate, fumed silica, phthalocyamine (e.g., phthalocyamine blue), ultramarine blue, cobalt blue, monoazo pigments, diazo pigments, acid dye, base dye, quinacridone, and a mixture thereof. In some embodiments, the colorant masterbatch can further include one or more additives, which can either be derived from a renewable resource or a non-renewable resource. Nonlimiting examples of additives include slip agents, UV absorbers, nucleating agents, UV stabilizers, heat stabilizers, clarifying agents, fillers, brighteners, process aids, perfumes, flavors, and a mixture thereof.

In some embodiments, color can be imparted to the films of the present invention in any of the aspects by using direct compounding (i.e., in-line compounding). In these embodiments, a twin screw compounder is placed at the beginning of the injection molding, blow molding, or film line and additives, such as pigments, are blended into the resin just before article formation.

Additional materials may be incorporated into the packages of the present invention in any of the aspects to improve the strength or other physical characteristics of the plastic. Such additional materials include an inorganic salt, such as calcium carbonate, calcium sulfate, tales, clays (e.g., nanoclays), aluminum hydroxide, CaSiO3, glass fibers, glass spheres, crystalline silicas (e.g., quartz, novacite, crystallobite), magnesium hydroxide, mica, sodium sulfate, lithopone, magnesium carbonate, iron oxide, or a mixture thereof.

In some alternative embodiments to any of the embodiments described herein, elements of the package, including the sealant, barrier material, tie layers, or mixtures thereof, include recycled material in place of, or in addition to, the bio-based material in an amount of up to 100% of the bio-based material. As used herein, “recycled” materials encompass post-consumer recycled (PCR) materials, post-industrial recycled (PIR) materials, and a mixture thereof.

In some embodiments, the structure described above may incorporate a barrier layer. The barrier material is selected from the group consisting of aluminum, metallized polyolefin substrate, metallized polyethylene terephthalate substrate, metallised cellulose. PVDC, PCTFE, sol-gel coating. Instead of a metallized coating on polyolefins or polyethylene terephthalate, the following coatings could be used—metal oxide, a nanoclay, an aluminum oxide, a silicon oxide, diamond-like carbon (DLC), and mixtures thereof. Other barrier substrates (used with or without a coating) could include EVOH, PVOH, Nylon, PVC, liquid crystal polymer. The substrates could include within their structure, an additional barrier additive (not in coating form but embedded within the polymer matrix)—one example of such additives could include nanoclays). The total barrier layer including the substrate typically has a thickness of about 6 [mu]m to about 200 [mu]m. Typically the substrate underneath the coating is cast biaxially oriented, although it could be a blown or cast film too. In some preferred embodiments, the metal is vacuum metallized aluminum. In some embodiments when the barrier material is a nanoclay, the nanoclay is selected from the group consisting of montmorillonites, vermiculite platelets, and mixtures thereof.

In embodiments of the consumer packages described herein, the ink that is deposited can be either solvent-based or water-based. In some embodiments, the ink is high abrasive resistant. For example, the high abrasive resistant ink can include coatings cured by ultraviolet radiation (UV) or electron beams (EB). In some embodiments, the ink is derived from a petroleum source. In some embodiments, the ink is derived from a renewable resource, such as soy, a plant, or a mixture thereof. Non-limiting examples of inks include ECO-SURE!™ from Gans Ink & Supply Co. and the solvent-based VUTEk® and BioVu™ inks from EFI, which are derived completely from renewable resources (e.g., corn). The ink is present in a thickness of about 0.5 [mu]m to about 20 [mu]m, preferably about 1 [mu]m to about 10 [mu]m, more preferably about 2.5 [mu]m to about 3.5 [mu]m.

In embodiments of the consumer packages described herein, an optional lacquer functions to protect the ink layer from its physical and chemical environment, when reverse printing has not been used. In some embodiments, the lacquer is selected from the group consisting of resin, additive, and solvent/water. In some preferred embodiments, the lacquer is nitrocellulose-based lacquer. The lacquer is formulated to optimize durability and provide a glossy or matte finish. The lacquer is present in a thickness of up to about 25 [mu]m, preferably up to about 5 [mu]m.

Non-limiting examples of the adhesive can include acrylic, polyvinyl acetate, and other commonly used adhesive tie layers suitable for polar materials. In some embodiments, the adhesive is a renewable adhesive, such as BioTAK® by Berkshire Labels.

In some embodiments, particular material combinations that enable the film structure to be biodegradable or degradable may be selected.

In some embodiments, the consumer packages described herein are substantially free of oxo-biodegradable additives (i.e., less than about 1 wt. %, based on the total weight of the package or article) but in some embodiments oxo-biodegradable additives may be used. Oxo-biodegradable additives consist of transition metals that theoretically foster oxidation and chain scission in plastics when exposed to heat, air, light, or a mixture thereof. Although the shortened polymer chains theoretically can be consumed by microorganisms found in the disposal environment and used as a food source, there is no data to support how long these plastic fragments will persist in the soils or marine environments, or if biodegradation of these fragments occurs at all. However, in some specific material blends, such materials may enable faster biodegradation.

In addition embodiments where a biodegradable package is desired, certain additives may be added to tune the degradability of polymers to meet a specific degradability. For example, numerous additives are known to tune the degradation of polymers with or without being triggered by some external stimulus (e.g., exposure to light) as disclosed in US 2010/0222454 A1, US 2004/0010051 A1, US2009/0286060 A1 and references therein. Additionally, the article “Photodegradation, Photooxidation, and Photostabilization of Polymers,” by Ranby and Rabek describe photodegradant materials. While not wishing to be bound by theory, one example of these additives (photo acid or photobase generators) tune the local pH in response to exposure to certain wavelengths of light, which results in hydrolysis of a polyester. Once these polymers are hydrolyzed to a lower molecular weight, they are truly biodegraded by microorganisms.

Opacity

As discussed above, the opacity of plastic films is adjusted using whitening additives to achieve a desired appearance and protection against light. While many methods can be used to determine the opacity of a plastic film, two exemplary test methods are described in ASTM 2805 and ISO 2471. Opacity is generally expressed in terms of a percentage of light that is absorbed by the film. For opaque LDPE thin films used in packaging, an opacity value of from about 35% to about 99% is usually acceptable.

Typically, a reduction in film caliper results in a loss of opacity, which requires an increase in whitening additives such as titanium dioxide, or other coloring additives. Thus, it would seem that the substitution of a foamed thin film for a non-foamed thin film would likewise require an increased amount of whitening or coloring additives to compensate for the reduction in the amount of resin that is present in the foamed thin film. In addition, the presence of voids in the foamed thin film would seem to further reduce the opacity of the foamed thin film as compared to a non-foamed film counterpart.

It has been discovered that the reduction in opacity of a foamed thin film (e.g., mono film 10 in FIG. 1b) as compared to its non-foamed thin film counterpart (e.g., mono film 100 in FIG. 1a) is not proportional with respect to the reduction in resin weight. In other words, the opacity of the foamed thin film (e.g., mono film 10) is only slightly lower than the opacity of the non-foamed thin film counterpart (e.g., mono film 100) even when a significant amount of the resin has been removed due to foaming. The degradation in opacity is much less than would be expected based on the reduction in resin weight. This may be due to light reflecting back at many angles as it encounters the curved inner surfaces of the voids left by bubbles. As such, in many instances it is not necessary to make any adjustments to the amount of whitening or coloring additives used to achieve a desired opacity when using a foamed thin film in place of a non-foamed film of substantially the same caliper and composition. However, in the case where bio-new materials are used to make the foamed films (especially bio-new materials blended into a petro-based material such as polyethylene), we see yet even higher increase in opacity, due to the typical incompatibility with the polyolefin matrix, which causes an increase in the reflectivity of light impinging on the sample.

As can be seen by the foregoing description, the use of foamed thin films in consumer packaging applications that include opening features allows for resin savings and, surprisingly, the methods of producing the opening features as well as the configuration of the opening features remains substantially the same as with non-foamed thin films of substantially the same caliper. In addition, foamed thin films provide substantially similar levels of opacity to their non-foamed thin film counterparts. These discoveries allow for a new and ready use of foamed thin films for non-foamed thin films in packages with opening features and/or a need for a level of opacity.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”.

Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A package comprising at least one layer of foamed thin film having gaseous bubbles, void volumes, or cells, wherein the layer of foamed thin film comprises:

i. a bio-based content of between about 10% and about 100%;

ii. a caliper of between about 10 and 250 microns; and

iii. a density reduction of between about a 5% to 50%, as compared to a non-foamed thin film of substantially the same caliper that does not comprise gaseous bubbles, void volumes, or cells.

2. The package of claim 1, wherein the package further comprises an opening feature selected from the group consisting of: a line of weakness and a die cut that defines a dispensing opening, formed in the layer of foamed thin film.

3. The package of claim 1, wherein the layer of foamed thin film comprises a bio-based content of between about 50% and about 100%.

4. The package of claim 1, wherein the bio-based content comprises between about 5% and about 96% of bio-identical materials.

5. The package of claim 1, wherein the bio-based content comprises between about 5% and about 50% of bio-new materials.

6. The package of claim 1, wherein the bio-based content is sourced from a renewable resource.

7. The package of claim 1, wherein the package comprises synthetic polymers derived from a renewable resource via an indirect route with an intermediate compound comprising sugar or vegetable starch.

8. The package of claim 1, wherein the package comprises polymers derived directly from renewable resources and the polymers are selected from a group consisting of: cellulose, starch, poly(lactic acid), and polyhydroxyalkanoates.

9. The package of claim 2, wherein the opening feature comprises a line of weakness.

10. The package of claim 1 wherein the package comprises a foamed thin film co-extrusion that includes at least one foamed thin film layer.

11. The package of claim 10, wherein the foamed thin film co-extrusion comprises a top layer, a core layer, and a lower layer, wherein the core layer is a foamed thin film layer.

12. The package of claim 1, wherein the package comprises a foamed thin film laminate that includes at least one foamed thin film layer.

13. The package of claim 12, wherein the foamed thin film laminate comprises a top layer, a core layer, and a lower layer, wherein the core layer is a foamed thin film layer.

14. A package comprising at least one layer of foamed thin film having gaseous bubbles, void volumes, or cells, wherein the layer of foamed thin film comprises:

i. a bio-based content of between about 10% and about 100%;

ii. a caliper of between about 10 and 250 microns;

iii. a whitening additive; and

iv. a density reduction of between about a 5% to 50%, as compared to a non-foamed thin film of substantially the same caliper that does not comprise gaseous bubbles, void volumes, or cells;

wherein the whitening additive is selected to produce a foamed thin film having an opacity value of between about 35-99%.

15. The package of claim 14, wherein the package further comprises an opening feature selected from the group consisting of: a line of weakness and a die cut that defines a dispensing opening, formed in the layer of foamed thin film.

16. The package of claim 14, wherein the layer of foamed thin film comprises a bio-based content of between about 50% and about 100/%.

17. The package of claim 14, wherein the bio-based content comprises between about 5% and about 96% of bio-identical materials.

18. The package of claim 14, wherein the bio-based content comprises between about 5% and about 50% of bio-new materials.

19. The package of claim 14, wherein the bio-based content is sourced from a renewable resource.

20. The package of claim 14, wherein the package comprises synthetic polymers derived from a renewable resource via an indirect route with an intermediate compound comprising sugar or vegetable starch.

21. The package of claim 14, wherein the package comprises polymers derived directly from renewable resources and the polymers are selected from a group consisting of: cellulose, starch, poly(lactic acid), and polyhydroxyalkanoates.

22. The package of claim 14, wherein the whitening agent comprises titanium dioxide.

23. The package of claim 15, wherein the opening feature comprises a line of weakness.

24. The package of claim 14, wherein the package comprises a foamed thin film co-extrusion that includes at least one foamed thin film layer.