PHA-based retort food pouch

Abstract

A retort food pouch is disclosed that includes at least one sidewall and a pouch closure. The sidewall is a multi-layer structure that is comprised of: (1) a biodegradable heat sealable layer that includes a polyhydroxyalkanoate, (2) a barrier layer that includes aluminum and / or a polyhydroxyalkanoate, (3) an optional nylon layer, and (4) a biodegradable print layer that also includes a polyhydroxyalkanoate and / or cellulose. The layers are bonded together with one or more adhesives to form the multi-layer structure.

Description

[Technical field]

[0001] The present disclosure relates to biodegradable polymer compositions. More particularly, the present disclosure relates to retort food pouches formed from multi-layer structures that include layers that are biodegradable and / or home compostable. [Background technology]

[0002] In food packaging, retort processing is a method in which food is cooked and stored at high temperatures, then vacuum sealed in a pouch-like food packaging for later consumption. This process extends the shelf life of food products and allows food products to be sold as "instant", where the food can be eaten as is or reheated. Retort processing is preferred over canning because it results in lighter packaging for shipping and less energy required for production. Common foods produced via retort processing include meats, soups, rice, and curries, with the most common example of retort packaging being Meals Ready to Eat (MREs). MREs are most commonly used by the military.

[0003] Retort packaging must be capable of being heat sealed and cooked at high temperatures (approximately 120°C) while providing barrier performance against water and oxygen. For commercial use, it must also be printable for marketing purposes. These performance requirements are met by using multiple layers of materials, each layer serving a specific purpose. Traditionally, such materials include polypropylene, nylon, polyethylene terephthalate, polyethylene, and aluminum. However, the plastics used are petroleum-based and not a sustainable option. Furthermore, recycling such packaging has proven difficult as different materials are difficult to separate and, if recycled together, degrade the quality of the individual recycling streams.

[0004] It would be desirable to provide a multi-layer food packaging structure suitable for preparing retort food packages, where at least some of the individual layers of the multi-layer structure are biodegradable and / or compostable. It would be preferable if the entire retort food package were biodegradable and / or compostable. Summary of the Invention

[0005] These and other needs are met by a retort food pouch provided in accordance with the present disclosure. According to one embodiment, the retort food pouch comprises at least one sidewall and a pouch closure. The at least one sidewall is a multi-layer structure comprised of: (1) a biodegradable heat sealable layer, which comprises a polyhydroxyalkanoate; (2) a barrier layer, which comprises aluminum and / or a polyhydroxyalkanoate; (3) an optional nylon layer; and (4) a biodegradable print layer, which also comprises a polyhydroxyalkanoate and / or cellulose. The layers are adhered together with one or more adhesives to form the multi-layer structure.

[0006] In certain embodiments, the biodegradable heat-sealable layer preferably comprises: (1) about 10 to about 99 weight percent of a polyhydroxyalkanoate; (2) about 1 to about 90 weight percent of at least one biodegradable polymer, the biodegradable polymer being selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; and (3) about 0.1 weight percent to about 5 weight percent of at least one nucleating agent, the nucleating agent being erythritol. and (4) optionally, from about 1 to about 25 weight percent of at least one bulking agent, the bulking agent being selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof.

[0007] In some embodiments, the polyhydroxyalkanoate of the biodegradable heat-sealable layer more preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0008] In some examples, the biodegradable, heat-sealable layer more preferably comprises from about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0009] In accordance with some embodiments, the biodegradable, heat-sealable layer more preferably comprises a polyhydroxyalkanoate terpolymer comprised of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0010] In certain embodiments, the biodegradable, heat-sealable layer preferably comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0011] In accordance with certain embodiments, the barrier layer preferably comprises: (1) about 10 to about 99 weight percent of a polyhydroxyalkanoate; (2) about 1 to about 90 weight percent of at least one biodegradable polymer, the biodegradable polymer being selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; and (3) about 0.1 weight percent to about 5 weight percent of at least one nucleating agent, the nucleating agent being erythritol, pentane, butyl ether ... and (4) optionally, from about 1 to about 25 weight percent of at least one bulking agent, the bulking agent being selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof.

[0012] In some instances, the polyhydroxyalkanoate of the barrier layer is preferably comprised of poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0013] In some embodiments, the barrier layer preferably comprises from about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0014] In another embodiment, the barrier layer preferably comprises a polyhydroxyalkanoate terpolymer composed of from about 75 to about 99.9 mole percent of the monomeric residues of 3-hydroxybutyrate, from about 0.1 to about 25 mole percent of the monomeric residues of 3-hydroxyhexanoate, and from about 0.1 to about 25 mole percent of the monomeric residues of a third 3-hydroxyalkanoate selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0015] According to one particular embodiment, the barrier layer preferably comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0016] In some cases, the barrier layer preferably comprises aluminum.

[0017] In some embodiments, the multi-layer structure preferably has a total thickness of about 25 to about 75 microns. The aluminum barrier layer preferably has a thickness of about 3 to about 13 microns. The optional biaxially oriented nylon layer, if present, is preferably about 5 to about 15 microns in thickness.

[0018] According to some embodiments, the biodegradable print layer preferably comprises: (1) about 10 to about 99 weight percent of a polyhydroxyalkanoate; (2) about 1 to about 90 weight percent of at least one biodegradable polymer, the biodegradable polymer being selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; and (3) about 0.1 weight percent to about 5 weight percent of at least one nucleating agent, the nucleating agent being erythritol, and (4) optionally, from about 1 to about 25 weight percent of at least one bulking agent selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof.

[0019] According to one particular embodiment, the biodegradable printing layer is preferably composed of a core sub-layer and at least one skin sub-layer.

[0020] In some examples, the polyhydroxyalkanoate of the biodegradable print layer more preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0021] In some embodiments, the biodegradable printed layer is more preferably about 1.0 to about 15.0 wt. percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0022] In accordance with certain embodiments, the biodegradable print layer more preferably comprises a polyhydroxyalkanoate terpolymer comprised of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0023] In some embodiments, the biodegradable print layer preferably comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0024] Alternatively, according to some embodiments, the print layer may be composed of a biodegradable cellulosic material.

[0025] In some instances, the biodegradable print layer is preferably from about 5 to about 25 microns in thickness.

[0026] According to certain embodiments, the biodegradable printed layer is preferably printed using flexographic, gravure, or digital printing methods.

[0027] In some embodiments, the layers of the multi-layer structure are preferably adhered together using at least one adhesive, which comprises at least one polymer selected from the group consisting of polycaprolactone, isocyanate, polyurethane, polybutylene succinate-co-adipate, polybutylene adipate-co-terephthalate, polyhydroxyalkanoate, polylactic acid, and mixtures thereof.

[0028] In certain embodiments, all layers of the multi-layer structure preferably have a melting point greater than 120° C. as specified by ASTM E794-06.

[0029] In some embodiments, the retort food pouch has a shelf life of at least 18 months as specified by ASTM E2454.

[0030] According to certain preferred embodiments, the multi-layer structure has an oxygen transmission rate of less than 0.45 ml / m2 / 24 h as determined according to ASTM D3985. Furthermore, the multi-layer structure also preferably has a water vapor transmission rate of less than 0.2 g / m2 / 24 h as determined according to ASTM F1249. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] As used herein, the term "biodegradable" refers to plastic or polymeric materials that will undergo biodegradation by living organisms (microorganisms) in anaerobic or aerobic environments as specified by ASTM D5511 (anaerobic) and D5338 (aerobic).

[0032] As used herein, the term "compostable" refers to plastic or polymeric materials that will undergo biodegradation in a home composting environment as specified by ASTM D6868.

[0033] In a first aspect, the present disclosure provides a retort food pouch. The retort food pouch comprises at least one sidewall and a pouch closure. A series of retort food pouches are first formed from a roll of the multilayer film structure. Each pouch is formed by folding and heat sealing a length of the multilayer film structure along the bottom and sides of the pouch. The general shape of the pouch thus formed has an open top.

[0034] The top of the pouch is then opened and the pouch is filled with the food product. In some instances, the solid and liquid portions of the food product can be added to the retort pouch in separate food filling stations. The inside of the retort pouch can also be flushed with nitrogen gas to create a low oxygen environment within the pouch, thereby improving the food product shelf life.

[0035] The top of the filled pouch is then heat sealed. The filled and sealed pouch can be heated to cook and sterilize the pouch and its food contents.

[0036] Now for the sidewall of the retort pouch, this is provided by a multi-layer film structure. This multi-layer structure typically comprises at least: (1) a biodegradable heat sealable layer, which comprises polyhydroxyalkanoate; (2) a barrier layer, which comprises aluminum and / or polyhydroxyalkanoate; and (3) a biodegradable print layer, which also comprises polyhydroxyalkanoate and / or cellulose. In some examples, the multi-layer structure may also comprise a nylon film layer. That is, in such an embodiment, the multi-layer structure is composed of: (1) a biodegradable heat sealable layer, which comprises polyhydroxyalkanoate; (2) a barrier layer, which comprises aluminum and / or polyhydroxyalkanoate; (3) a nylon layer; and (4) a biodegradable print layer, which also comprises polyhydroxyalkanoate and / or cellulose.

[0037] In general, the multi-layer structure preferably has a total thickness of from about 25 to about 75 microns.

[0038] As described above, the first layer of the multi-layer structure is a biodegradable heat-sealable layer, which comprises at least one form of polyhydroxyalkanoate. In some cases, the polyhydroxyalkanoate of the heat-sealable layer can be a homopolymer. However, more typically, the polyhydroxyalkanoate of the heat-sealable layer comprises a polyhydroxyalkanoate copolymer or terpolymer.

[0039] For example, in certain embodiments, the biodegradable, heat-sealable layer can include a polyhydroxyalkanoate copolymer, such as poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0040] More typically, the biodegradable, heat-sealable layer can comprise from about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate having from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0041] In other embodiments, the biodegradable, heat-sealable layer can include a polyhydroxyalkanoate terpolymer comprised of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0042] Generally, the polyhydroxyalkanoates of the biodegradable heat-sealable layer can have a weight average molecular weight of from about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0043] In general, the amount of polyhydroxyalkanoate in the biodegradable heat-sealable layer is preferably from about 10 to about 99 weight percent of the heat-sealable layer.

[0044] In some cases, the heat-sealable layer can also include about 1 to 90 weight percent of at least one additional biodegradable polymer, preferably selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof.

[0045] The heat-sealable layer also generally includes a nucleating agent. Preferably, the heat-sealable layer includes from about 0.1 weight percent to about 5 weight percent of at least one nucleating agent selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof.

[0046] In some examples, the heat-sealable layer may also include about 1 to about 25 weight percent of at least one filler selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof. A particularly preferred filler is talc.

[0047] The multi-layer structure also includes a barrier layer that acts to limit the transmission of atmospheric oxygen and / or moisture through the multi-layer structure, the barrier layer comprising aluminum and / or polyhydroxyalkanoate.

[0048] For example, the barrier may include only an aluminum layer. In such embodiments, the aluminum barrier layer is preferably about 3 to about 13 microns thick. In other embodiments, the barrier layer may be provided by a layer including polyhydroxyalkanoate. In yet other embodiments, the barrier layer may be comprised of a sub-layer of aluminum and a sub-layer of polyhydroxyalkanoate.

[0049] When a polyhydroxyalkanoate is present in the barrier layer, the polyhydroxyalkanoate may comprise a homopolymer, copolymer, or terpolymer.

[0050] That is, the barrier layer may be a polyhydroxyalkanoate copolymer, such as poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HH Typically, the barrier layer can comprise from about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0051] In other embodiments, the barrier layer may comprise a polyhydroxyalkanoate terpolymer comprised of from about 75 to about 99.9 mole percent of the monomeric residues of 3-hydroxybutyrate, from about 0.1 to about 25 mole percent of the monomeric residues of 3-hydroxyhexanoate, and from about 0.1 to about 25 mole percent of the monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0052] In certain embodiments, the heat-sealable layer can also include about 1 to 90 weight percent of at least one additional biodegradable polymer, preferably selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof.

[0053] The barrier layer preferably also includes a nucleating agent. Preferably, the heat-sealable layer includes from about 0.1 weight percent to about 5 weight percent of at least one nucleating agent selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof.

[0054] In some cases, the barrier layer may also include from about 1 to about 25 weight percent of at least one filler selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof. A particularly preferred filler is talc.

[0055] In some embodiments, the multi-layer structure may also include a layer of nylon film in addition to the heat sealable layer, aluminum barrier layer, and print layer. If present, the additional nylon layer provides additional strength, durability, and puncture resistance to the multi-layer structure.

[0056] If present, the nylon film layer is typically stretch oriented, preferably biaxially oriented, and the nylon layer also preferably has a thickness of from about 5 to about 15 microns.

[0057] The multi-layer structure also includes a biodegradable printed layer, the printed layer comprising at least one form of polyhydroxyalkanoate and / or cellulose, the biodegradable printed layer preferably having product packaging information printed thereon using flexographic, gravure, or digital printing methods.

[0058] Similar to the heat-sealable layer discussed above, the print layer can include a polyhydroxyalkanoate in the form of a homopolymer, copolymer, or terpolymer. Alternatively, according to some embodiments, the print layer can be composed of a biodegradable cellulosic material.

[0059] For example, the biodegradable print layer can include a polyhydroxyalkanoate copolymer, such as poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0060] More typically, the biodegradable print layer can include from about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate having from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0061] In other embodiments, the biodegradable print layer can include a polyhydroxyalkanoate terpolymer comprised of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0062] Typically, the polyhydroxyalkanoate of the biodegradable print layer has a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0063] In general, the amount of polyhydroxyalkanoate in the biodegradable print is preferably from about 10 to about 99 weight percent of the heat sealable layer.

[0064] According to certain embodiments, the print layer can also include about 1 to 90 weight percent of at least one additional biodegradable polymer. The additional biodegradable polymer is preferably selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof. Furthermore, the print layer also generally includes a nucleating agent. Preferably, the heat-sealable layer includes about 0.1 weight percent to about 5 weight percent of at least one nucleating agent, the nucleating agent being selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester wax, nanoclay, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof.

[0065] Preferably, the biodegradable print layer is about 5 to about 25 microns thick.

[0066] Each of the individual layers is bonded together with one or more adhesives to form the multi-layer structure. Preferably, the adhesive comprises a biodegradable material (as specified by ASTM D5338) and / or compostable (as specified by ASTM D6400). For example, in some embodiments, the layers of the multi-layer structure can be bonded together with at least one adhesive comprising at least one polymer selected from the group consisting of polycaprolactone, isocyanate, polyurethane, polybutylene succinate-co-adipate, polybutylene adipate-co-terephthalate, polyhydroxyalkanoate, polylactic acid, and mixtures thereof.

[0067] The multi-layer structures prepared according to the present disclosure provide good barrier properties for the storage and preservation of food products enclosed in retort pouches.

[0068] In particular, in certain embodiments, the multi-layer structure preferably has an oxygen transmission rate of 0.45 ml / m2 or greater as determined according to ASTM D3985. 2 / 24h. In comparison, polyethylene terephthalate (PET) films typically have an oxygen transmission rate of about 15 to about 90 ml / m 2 / 24h. Polyethylene (PE) film, under the same test conditions, typically has an oxygen transmission rate of about 1550 to about 2500 ml / m 2 / 24h.

[0069] Furthermore, the multi-layer structure also preferably has a water vapor transmission rate of 0.2 g / m according to ASTM F1249. 2 / 24h. In comparison, polyethylene terephthalate (PET) film typically has a water vapor transmission rate of about 1.5 ml / m2 under the same test conditions. 2 / 24h~approx.80ml / m 2 / 24h. Polyethylene (PE) film, under the same test conditions, typically has a water vision transmission rate of about 1.5 ml / m 2 / 24h ~ approx. 15.5ml / m 2 / 24h.

[0070] The retort food pouch also preferably has a shelf life of at least 18 months as specified by ASTM E2454.

[0071] Furthermore, all layers of the multi-layer structure preferably have a melting point, as specified by ASTM E794-06, greater than 120° C. More preferably, all layers of the multi-layer structure preferably have a melting point, as specified by ASTM E794-06, greater than 150° C. Since retort packaged foods are generally cooked / sterilized in retort pouches at a temperature of about 136° C., the higher melting point of the material used to form the pouch ensures that the integrity of the pouch is maintained during the food cooking process.

[0072] At the same time, at least the heat-sealable layer and the print layer of the multi-layer sidewall structure are biodegradable. Preferably, at least the heat-sealable layer and the print layer of the multi-layer sidewall structure are also home compostable. If the optional nylon layer is omitted, all polymer-based layers of the multi-layer sidewall structure are preferably biodegradable and / or home compostable.

[0073] The present disclosure is further illustrated by the following embodiments:

[0074] Embodiment 1. A retort food pouch having at least one sidewall and a pouch closure, said at least one sidewall comprising:

[0075] a biodegradable heat-sealable layer, which comprises a polyhydroxyalkanoate; and

[0076] a barrier layer, which comprises aluminum and / or polyhydroxyalkanoate; and

[0077] Optionally, a nylon layer, and

[0078] a biodegradable printing layer, which comprises polyhydroxyalkanoate and / or cellulose; and A multilayer structure comprising:

[0079] The retort food pouch, wherein the layers are bonded together with one or more adhesives to form the multi-layer structure.

[0080] Embodiment 2. The biodegradable, heat-sealable layer comprises:

[0081] about 10 to about 99 weight percent of a polyhydroxyalkanoate;

[0082] about 1 to 90 weight percent of at least one biodegradable polymer, the biodegradable polymer being selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof;

[0083] from about 0.1 weight percent to about 5 weight percent of at least one nucleating agent, the nucleating agent being selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof; and

[0084] optionally, from about 1 to about 25 weight percent of at least one filler, the filler being selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof; 2. The retort food pouch of embodiment 1, comprising:

[0085] Embodiment 3. The retort food pouch of embodiment 1 or 2, wherein the polyhydroxyalkanoate of the biodegradable heat sealable layer comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0086] Embodiment 4. The retort food pouch of any one of the preceding embodiments, wherein the biodegradable, heat-sealable layer comprises about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0087] Embodiment 5. The retort food pouch of any one of the preceding embodiments, wherein the biodegradable, heat-sealable layer comprises a polyhydroxyalkanoate terpolymer comprised of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0088] Embodiment 6. The retort food pouch of any one of the preceding embodiments, wherein the biodegradable, heat-sealable layer comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0089] Embodiment 7. The barrier layer comprises:

[0090] about 10 to about 99 weight percent of a polyhydroxyalkanoate;

[0091] about 1 to 90 weight percent of at least one biodegradable polymer, the biodegradable polymer being selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof;

[0092] from about 0.1 weight percent to about 25 weight percent of at least one nucleating agent, the nucleating agent being selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof; and

[0093] optionally, from about 1 to about 25 weight percent of at least one filler, the filler being selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof; 4. The retort food pouch of any one of the preceding embodiments, comprising:

[0094] Embodiment 8. The retort food pouch of embodiment 7, wherein the polyhydroxyalkanoate of the barrier layer comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0095] Embodiment 9. The retort food pouch of embodiment 7 or 8, wherein the barrier layer comprises from about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising from about 25 to about 50 mole percent of monomeric residues of a 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0096] Embodiment 10. The retort food pouch of any one of embodiments 7-9, wherein the barrier layer comprises a polyhydroxyalkanoate terpolymer composed of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0097] Embodiment 11. A retort food pouch according to any one of embodiments 7 to 10, wherein the barrier layer comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0098] Embodiment 12. The retort food pouch of embodiment 7, wherein the barrier layer comprises aluminum.

[0099] Embodiment 13. The retort food pouch of any one of the preceding embodiments, wherein the multi-layer structure has an overall thickness of about 25 to about 75 microns.

[0100] Embodiment 14. The aluminum barrier layer has a thickness of about 3 to about 13 microns. 3. The retort food pouch of any one of the embodiments.

[0101] Embodiment 15. A retort food pouch according to any one of the preceding embodiments, wherein the multi-layer structure comprises a biaxially oriented nylon layer having a thickness of about 5 to about 15 microns.

[0102] Embodiment 16. The biodegradable printing layer comprises:

[0103] about 10 to about 99 weight percent of a polyhydroxyalkanoate;

[0104] about 1 to 90 weight percent of at least one biodegradable polymer, the biodegradable polymer being selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; and

[0105] from about 0.1 weight percent to about 5 weight percent of at least one nucleating agent, the nucleating agent being selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof; 4. The retort food pouch of any one of the preceding embodiments, comprising:

[0106] Embodiment 17. A retort food pouch as described in embodiment 16, wherein the polyhydroxyalkanoate of the biodegradable printed layer comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

[0107] Embodiment 18. A retort food pouch as described in embodiment 16 or 17, wherein the biodegradable printed layer comprises about 1.0 to about 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising about 25 to about 50 mole percent of monomeric residues of 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0108] Embodiment 19. A retort food pouch according to any one of embodiments 16 to 18, wherein the biodegradable printed layer comprises a polyhydroxyalkanoate terpolymer, the terpolymer being composed of about 75 to about 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

[0109] Embodiment 20. A retort food pouch according to any one of embodiments 16 to 19, wherein the biodegradable printed layer comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0110] Embodiment 21. A retort food pouch according to any one of embodiments 16 to 20, wherein the biodegradable printed layer is about 5 to about 25 microns thick.

[0111] Embodiment 22. A retort food pouch according to any one of the preceding embodiments, wherein the biodegradable printed layer is printed using a flexographic, gravure, or digital printing method.

[0112] Embodiment 23. The retort food pouch of any one of the preceding embodiments, wherein the layers are bonded together using at least one adhesive comprising at least one polymer selected from the group consisting of polycaprolactone, isocyanate, polyurethane, polybutylene succinate-co-adipate, polybutylene adipate-co-terephthalate, polyhydroxyalkanoate, polylactic acid, and mixtures thereof.

[0113] Embodiment 24. A retort food pouch according to any one of the preceding embodiments, wherein all of the layers of the multi-layer structure have a melting point greater than 120°C as specified by ASTM E794-06.

[0114] Embodiment 25. The retort food pouch of any one of the preceding embodiments, wherein the retort food pouch has a shelf life of at least 18 months as specified by ASTM E2454.

[0115] Embodiment 26. A retort food pouch according to any one of the preceding embodiments, wherein the multi-layer structure has an oxygen transmission rate, as determined according to ASTM D3985, of less than 0.45 ml / m2 / 24 h.

[0116] Embodiment 27. The retort food pouch of any one of the preceding embodiments, wherein the multi-layer structure has a moisture vapor transmission rate, as determined according to ASTM F1249, of less than 0.2 g / m2 / 24 h. EXAMPLES

[0117] The following examples are not limiting but illustrate various additional aspects of the present invention. Unless otherwise stated, temperatures are in degrees Celsius and percentages are weight percentages based on the dry weight of the formulation.

[0118] Example 1

[0119] In this example, a series of formulations suitable for biodegradable films were compounded in an Entek twin screw extruder. The composition of the formulations (weight percent) is shown in Table 1 below: [Table 1]

[0120] Example 1

[0121] In this example, the resin formulation of Example 1 above was converted into a blown film (1.25 mil) and tested for heat resistance under the following conditions: conventional convection oven (120°C, 5 min), boiling water (100°C / 30 min), and microwave oven (1000W, 90 sec). The film was evaluated for percent shrinkage in both the machine and cross directions. The results are shown in Table 2. [Table 2]

[0122] The foregoing description of preferred embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments have been chosen and described as part of an effort to provide the best explanation of the principles of the invention and its practical application, thereby enabling those skilled in the art to utilize the invention in various embodiments, and with various modifications as appropriate to the particular use contemplated. All such modifications and variations are within the scope of the present invention, as defined by the appended claims, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. 1. A retort food pouch having at least one side wall and a pouch closure, said at least one side wall comprising: a biodegradable, heat-sealable layer comprising a polyhydroxyalkanoate; a barrier layer comprising aluminum and / or polyhydroxyalkanoate; Optionally, a nylon layer, and A biodegradable printing layer comprising a polyhydroxyalkanoate; A multilayer structure comprising: The retort food pouch, wherein the layers are bonded together with one or more adhesives to form the multi-layer structure.

2. The biodegradable, heat-sealable layer comprises: 10 to 99 weight percent of a polyhydroxyalkanoate; 1 to 90 weight percent of at least one biodegradable polymer selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; 0.1 weight percent to 5 weight percent of at least one nucleating agent selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof; and Optionally, 1 to 25 weight percent of at least one bulking agent selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof; 2. The retort food pouch of claim 1 comprising:

3. 3. The retort food pouch of claim 2, wherein the polyhydroxyalkanoate of the biodegradable, heat sealable layer comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

4. 3. The retort food pouch of claim 2, wherein the biodegradable, heat-sealable layer comprises 1.0 to 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising 25 to 50 mole percent monomeric residues of 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

5. 3. The retort food pouch of claim 2, wherein the biodegradable, heat-sealable layer comprises a polyhydroxyalkanoate terpolymer comprised of 75 to 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, 0.1 to 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and 0.1 to 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

6. 3. The retort food pouch of claim 2, wherein the biodegradable, heat-sealable layer comprises a polyhydroxyalkanoate having a weight average molecular weight of about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

7. The barrier layer may be: 10 to 99 weight percent of a polyhydroxyalkanoate; 1 to 90 weight percent of at least one biodegradable polymer selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; 0.1 weight percent to 25 weight percent of at least one nucleating agent selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof; and Optionally, 1 to 25 weight percent of at least one bulking agent selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof; 2. The retort food pouch of claim 1 comprising:

8. 8. The retort food pouch of claim 7, wherein the polyhydroxyalkanoate of the barrier layer comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

9. 8. The retort food pouch of claim 7, wherein the barrier layer comprises 1.0 to 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising 25 to 50 mole percent monomeric residues of a 3-hydroxyalkanoate selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

10. 8. The retort food pouch of claim 7, wherein the barrier layer comprises a polyhydroxyalkanoate terpolymer comprised of 75 to 99.9 mole percent of the monomeric residues of 3-hydroxybutyrate, 0.1 to 25 mole percent of the monomeric residues of 3-hydroxyhexanoate, and 0.1 to 25 mole percent of the monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

11. 8. The retort food pouch of claim 7, wherein the barrier layer comprises a polyhydroxyalkanoate having a weight average molecular weight of from 50,000 Daltons to 2,500,000 Daltons as specified by ASTM D5296-05.

12. 10. The retort food pouch of claim 1, wherein the barrier layer comprises aluminum.

13. 10. The retort food pouch of claim 1, wherein the multi-layer structure has an overall thickness of 25 to 75 microns.

14. 10. The retort food pouch of claim 1, wherein the aluminum barrier layer is 3 to 13 microns in thickness.

15. 10. The retort food pouch of claim 1, wherein the multi-layer structure comprises a biaxially oriented nylon layer having a thickness of about 5 to about 15 microns.

16. The biodegradable printing layer comprises: 10 to 99 weight percent of a polyhydroxyalkanoate; 1 to 90 weight percent of at least one biodegradable polymer selected from the group consisting of polybutylene succinate, polycaprolactone, polybutylene succinate-co-butylene adipate, polybutylene adipate-co-terephthalate, polylactic acid, cellulose acetate, and mixtures thereof; 0.1 weight percent to 5 weight percent of at least one nucleating agent selected from the group consisting of erythritol, pentaerythritol, dipentaerythritol, artificial sweeteners, stearic acid compounds, sorbitol, mannitol, inositol, polyester waxes, nanoclays, behenamide, erucamide, stearamide, oleamide, polyhydroxybutyrate, boron nitride, and mixtures thereof; Optionally, 1 to 25 weight percent of at least one bulking agent selected from the group consisting of clay, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nanoclay, and mixtures thereof; 2. The retort food pouch of claim 1 comprising:

17. 10. The retort food pouch of claim 1, wherein the biodegradable printed layer comprises a core sub-layer and at least one skin sub-layer.

18. 17. The retort food pouch of claim 16, wherein the polyhydroxyalkanoate of the biodegradable print layer comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HHx).

19. 17. The retort food pouch of claim 16, wherein the biodegradable printed layer comprises 1.0 to 15.0 weight percent of at least one polyhydroxyalkanoate, the polyhydroxyalkanoate comprising 25 to 50 mole percent monomeric residues of 3-hydroxyalkanoate, the 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

20. 17. The retort food pouch of claim 16, wherein the biodegradable printed layer comprises a polyhydroxyalkanoate terpolymer comprised of 75 to 99.9 mole percent of monomeric residues of 3-hydroxybutyrate, 0.1 to 25 mole percent of monomeric residues of 3-hydroxyhexanoate, and 0.1 to 25 mole percent of monomeric residues of a third 3-hydroxyalkanoate, the third 3-hydroxyalkanoate being selected from the group consisting of 3-hydroxyvalerate, 3-hydroxyoctanoate, 3-hydroxydecanoate, and mixtures thereof.

21. 17. The retort food pouch of claim 16, wherein the biodegradable printed layer comprises a polyhydroxyalkanoate having a weight average molecular weight of 50,000 Daltons to 2,500,000 Daltons as specified by ASTM D5296-05.

22. 10. The retort food pouch of claim 1, wherein the biodegradable printed layer is 5 to 25 microns thick.

23. 10. The retort food pouch of claim 1, wherein the biodegradable printed layer is printed using a flexographic, gravure, or digital printing method.

24. The layers may be made of polycaprolactone, isocyanate, polyurethane, polybutylene succinate, 2. The retort food pouch of claim 1, wherein the pouch is bonded together with at least one adhesive comprising at least one polymer selected from the group consisting of poly(butylene adipate), poly(butylene adipate)-co-terephthalate, polyhydroxyalkanoate, polylactic acid, and mixtures thereof.

25. 10. The retort food pouch of claim 1, wherein all of said layers of said multi-layer structure have a melting point greater than 120° C. as specified by ASTM E794-06.

26. 10. The retort food pouch of claim 1, having a shelf life of at least 18 months as specified by ASTM E2454.

27. The multi-layer structure has an oxygen transmission rate of 0.45 ml / m as determined according to ASTM D3985. ２ 2. The retort food pouch of claim 1, wherein the storage time is less than 24 hours.

28. The multi-layer structure has a water vapor transmission rate of 0.2 g / m2 as determined according to ASTM F1249. ２ 2. The retort food pouch of claim 1, wherein the storage time is less than 24 hours.

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