Biopolymer-coated fiber food serving articles

Abstract

A biodegradable food serving article is disclosed, which includes a biodegradable substrate having at least one food contact surface. The substrate is made from cellulose fiber. The food serving article also includes a coating provided on the at least one food contact surface. The coating is composed of about 25 weight percent to about 60 weight percent of at least one biodegradable polymer, such as a polyhydroxyalkanoate. A method of making the biodegradable food serving article is also disclosed.

Description

[Technical field]

[0001] The present disclosure relates to biodegradable polymer compositions. More particularly, the present disclosure relates to disposable biodegradable food serving articles having a biodegradable polymer coating. [Background technology]

[0002] Consumers often use disposable food serving items such as plates, bowls, cups, take-out containers, straws, and cutlery or drinking utensils for convenience. Disposable food serving items are particularly useful for serving food at public gatherings or outdoor dining events.

[0003] Disposable food serving articles can be easily made from substrates such as cardboard, which degrade relatively quickly after disposal in a landfill. However, simple uncoated cardboard substrates generally perform poorly as food serving articles because cardboard readily absorbs water and / or oil, which ultimately compromises the strength of the cardboard. As a result, food serving articles made from cardboard are generally coated with a thin polymer layer to improve their resistance to water and oil.

[0004] Coatings made from polymers such as polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET) can significantly improve cardboard's resistance to water and / or oil absorption, but such polymers do not readily degrade or decay after being disposed of in a landfill, meaning that cardboard articles coated with such polymers may persist in landfills for hundreds of years after being discarded.

[0005] It would be desirable to provide new coatings for food serving articles that are completely biodegradable, and it would be particularly desirable if the biodegradable coatings provided good water and oil resistance, i.e., water and oil resistance comparable to that provided by conventional non-biodegradable coatings. Summary of the Invention

[0006] These and other needs are addressed by a biodegradable food serving article according to the present disclosure. According to one embodiment, the biodegradable food serving article includes a biodegradable substrate having at least one food contact surface. The substrate is made from cellulose fibers. The food serving article also generally includes an aqueous coating applied onto the at least one food contact surface. The coating, prior to curing or drying, is comprised of about 25 weight percent to about 60 weight percent, and typically about 40 weight percent to about 75 weight percent, of at least one biodegradable polymer.

[0007] In certain embodiments, the at least one biodegradable polymer is selected from the group consisting of polyhydroxyalkanoates, polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and mixtures thereof.

[0008] According to some embodiments, the at least one biodegradable polymer preferably comprises a polyhydroxyalkanoate. More preferably, according to certain embodiments of the present disclosure, the polyhydroxyalkanoate has a weight average molecular weight of about 50,000 to about 2.5 million Daltons.

[0009] In certain embodiments, the biodegradable substrate is preferably a biodegradable plate, cup, bowl, take-out container, straw or eating utensil.

[0010] In certain aspects, the biodegradable substrate comprises: Dispersed in a substrate, Preferably, about 25 to about 60 weight percent of at least one biodegradable polymer, about 0.1 to about 2.0 weight percent of a surfactant (e.g., wetting agent, dispersing agent), and about 0.1 to about 2.0 weight percent of a rheology control agent. and about 0.001 weight percent to about 2.0 weight percent of a biocide 、 Also includes.

[0011] In certain embodiments, at least a portion of the cellulose fibers are preferably derived from sugar cane, bagasse, wheatgrass, or recycled wood pulp.

[0012] According to certain aspects of the present disclosure, the coating is preferably provided on at least one food contact surface at a dry basis application weight of about 5 grams to about 50 grams per square meter.

[0013] According to some embodiments, the coating preferably exhibits a Cobb water absorption value of less than 25 grams per square meter as measured according to TAPPI standard T 441. In more particular embodiments, the coating exhibits a Kit Test grease resistance value of greater than Kit Value 5 as measured according to TAPPI standard T 559 cm-12.

[0014] In a second aspect, the present disclosure provides a method of making a biodegradable food serving article. According to one embodiment, the method includes the steps of providing a biodegradable aqueous dispersion comprised of water, about 25 weight percent to about 60 weight percent (or in some embodiments about 40 weight percent to about 75 weight percent) of at least one biodegradable polymer, about 0.1 weight percent to about 2.0 weight percent of a surfactant, about 0.1 weight percent to about 2.0 weight percent of a rheology modifier, optionally about 0.1 weight percent to about 1.0 weight percent of an antifoam agent, optionally about 1 weight percent to about 20 weight percent of a filler, and about 0.001 weight percent to about 2.0 weight percent of at least one biocide.

[0015] According to this method, a layer of an aqueous slurry is formed on a mold. The aqueous slurry includes water and about 10 weight percent to about 70 weight percent cellulose fiber. The aqueous slurry is then molded using a combination of heat and pressure. According to this method, the heat and pressure from the molding process dry at least a portion of the slurry to form a biodegradable substrate.

[0016] A quantity of the biodegradable aqueous dispersion is also applied onto a substrate to form a layer of the dispersion on the first side of the substrate, which layer is then cured to form a film coating on the first side of the biodegradable substrate.

[0017] According to some aspects of the method, the aqueous slurry also preferably contains from about 10 weight percent to about 70 weight percent of a biodegradable aqueous dispersion.

[0018] In certain embodiments of this method, the aqueous dispersion is preferably spray coated onto at least one surface of the formed slurry layer.

[0019] In certain embodiments of this method, it is preferred that the slurry is compacted at a temperature of about 85° C. to about 170° C. and a pressure of about 100 psi to about 1500 psi. In other preferred embodiments, the pressure is about 1000 psi to about 100,000 psi.

[0020] According to some aspects of the method, the slurry, when initially formed on the mold, preferably has a solids content of from about 10 percent to about 85 percent by weight.

[0021] In certain embodiments of this method, the aqueous dispersion, when applied onto the slurry layer, preferably has a solids content of from about 25 weight percent to about 60 weight percent, more preferably from about 25 weight percent to about 55 weight percent.

[0022] According to certain aspects of this method, the at least one biodegradable polymer is preferably selected from the group consisting of polyhydroxyalkanoates, polylactic acids, polycaprolactones, polybutylene succinates, polybutylene succinate adipates, polybutylene adipate terephthalates, and mixtures thereof.

[0023] In certain embodiments of this method, it is preferred that the at least one biodegradable polymer comprises a polyhydroxyalkanoate. More preferably, according to some embodiments of this method, the polyhydroxyalkanoate has a weight average molecular weight of about 50,000 to about 2.5 million Daltons. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Detailed Description In a first aspect, the present disclosure provides a biodegradable food serving article, which for example can be formed as a biodegradable plate, cup, bowl, take-out container, straw, or serving utensil.

[0025] Generally, a biodegradable food serving article includes a biodegradable substrate having at least one food contact surface and a coating applied to the at least one food contact surface.

[0026] The term "biodegradable" as used herein refers to plastic or polymeric coatings that will undergo biodegradation by living organisms (microorganisms) in anaerobic and aerobic environments (as measured by ASTM D5511), soil environments (as measured by ASTM 5988), freshwater environments (as measured by ASTM D5271 (EN 29408)), or marine environments (as measured by ASTM D6691). The biodegradability of biodegradable plastics can also be measured using ASTM D6868 and European EN 13432.

[0027] Again, the substrate for the food serving article is biodegradable and is generally formed from cellulose fibers, which will generally comprise from about 60 weight percent to about 99 weight percent of the substrate on a dry basis, and more preferably will comprise from about 75 weight percent to about 85 weight percent of the substrate.

[0028] In some instances, it is preferred that at least a portion of the cellulose fibers be derived from sugar cane, bagasse, wheatgrass, or recycled wood pulp.

[0029] In certain embodiments, the biodegradable substrate also preferably includes an amount of at least one biodegradable polymer, for example, the biodegradable substrate can include from about 25 weight percent to about 60 weight percent of at least one biodegradable polymer.

[0030] More preferably, additional additives can be included in the substrate along with the cellulose fibers and biodegradable polymer. For example, in certain embodiments, the biodegradable substrate comprises, in addition to the cellulose fibers: Dispersed (i.e., impregnated) in a substrate; about 25 weight percent to about 60 weight percent of at least one biodegradable polymer, about 0.1 weight percent to about 2.0 weight percent of surfactants (e.g., wetting agents and dispersing agents), about 0.1 weight percent to about 2.0 weight percent of rheology control agents, optionally about 0.1 weight percent to about 1.0 weight percent of antifoam agents, and optionally about 1% to about 20% of fillers. and about 0.001 weight percent to about 2.0 weight percent of a biocide 、 may include.

[0031] As used herein, a "rheology modifier" is a material that alters the flow properties of a dispersion (i.e., thinning or thickening the dispersion). Examples of suitable rheology modifiers can be selected from the group consisting of polysaccharides (e.g., starch, glucan, xanthan gum, guar gum, and seaweed extracts), viscosity reducers (e.g., the VISCOBYK family or blends including carboxylic acid esters and wetting and dispersing components), and viscosity enhancers (such as modified polyurethanes including the BYK400 family, or solutions of derivatives of copolymers of ethyl acrylate and methacrylic acid such as ALCOGUN).

[0032] As used herein, a "filler" is an organic or inorganic material that provides multiple functions to the dispersion. First, these materials increase the solid content of the dispersion. Second, fillers can modify the brightness and gloss of the formed film. Finally, fillers can also serve as thickeners. Examples of suitable fillers can be selected from clay, calcium carbonate, nanocellulose, kaolinite, montmorillonite, bentonite, silica, chitin, nanoclay talc, mica, bentonite, titanium dioxide, and mixtures thereof.

[0033] As used herein, an "antifoaming agent" is a material added to a mixture to reduce or eliminate foam generation during a coating or spraying process. Antifoaming agents are generally silicone and / or mineral-free materials. Examples of suitable antifoaming agents can be selected from the group consisting of polyether siloxanes (such as AIRASE 5355 or 5655 or TEGO FOAMEX 825, 902 or 1488), polyamide particles (such as BYK1640 or BYK016) and mixtures thereof.

[0034] As used herein, "surfactants" are added to dispersions to stabilize polymers in aqueous media. Surfactants generally consist of both hydrophobic and hydrophilic regions. In dispersions, these distinct regions align at the interface between the polymer particles and the aqueous medium, lowering the surface energy between the boundaries of the two phases and facilitating dispersion.

[0035] As used herein, a "wetting and dispersing agent" is a suitable type of surfactant that contributes to the stabilization of the polymer and the uniformity of the dispersion. These materials generally contain bulky groups that maintain the separation of suspended particles through steric hindrance, which helps prevent particle aggregation and settling. Wetting and dispersing agents also ensure that the particles are thoroughly wetted by the aqueous medium, promoting complete and uniform dispersion. Examples of suitable wetting and dispersing agents include, but are not limited to, BYK190, BYK192, BYK193, BYK184, TEGO755, or TEGO761, which are believed to be nonionic or slightly anionic copolymers.

[0036] As used herein, a "biocide" is a substance that kills living organisms and thus protects materials from microbial growth and adhesion. Biocides suitable for inclusion in this disclosure include ethylenediaminetetraacetic acid (EDTA) and benzisothiazoline.

[0037] As mentioned above, the food serving article also includes a coating applied on at least one food contact surface of the substrate. Optionally, other non-food contact surfaces of the substrate can also be coated. The coating generally comprises from about 25 weight percent to about 60 weight percent of at least one biodegradable polymer, and more preferably from about 40 weight percent to about 55 weight percent of at least one biodegradable polymer. In another embodiment, the coating can be from about 35 weight percent to about 50 weight percent of at least one biodegradable polymer.

[0038] It is generally preferred that the at least one biodegradable polymer in the coating is selected from the group consisting of polyhydroxyalkanoates, polylactic acids, polycaprolactones, polybutylene succinates, polybutylene succinate adipates, polybutylene adipate terephthalates, and mixtures thereof.

[0039] More preferably, at least one biodegradable polymer comprises a polyhydroxyalkanoate. A particularly suitable polyhydroxyalkanoate for use in the coating is poly-3-hydroxybutyrate-co-3-hydroxyhexanoate, i.e., P(3HB-co-3HHx). In certain embodiments, P(3HB-co-3HHx) can be predominant, i.e., only polyhydroxyalkanoate is present in the dispersion.

[0040] The P(3HB-co-3HHx) is then a copolymer comprised of both hydroxybutyrate and hydroxyhexanoate, and the relative amounts of the two components may vary somewhat. In general, however, it is preferred that the P(3HB-co-3HHx) be comprised of about 75 mole percent to about 99 mole percent hydroxybutyrate and about 1 mole percent to about 25 mole percent hydroxyhexanoate. More preferably, the P(3HB-co-3HHx) be comprised of about 85 mole percent to about 95 mole percent hydroxybutyrate and about 5 mole percent to about 15 mole percent hydroxyhexanoate.

[0041] More preferably, in accordance with certain aspects of the present disclosure, the polyhydroxyalkanoates have a weight average molecular weight of from about 50,000 to about 2.5 million Daltons.

[0042] In general, certain biodegradable polymers are preferred for inclusion in both the coating and the substrate as described above.

[0043] In certain embodiments of the present disclosure, it is preferred that the coating be applied onto at least one food contact surface at a dry basis application weight of about 5 grams to about 50 grams per square meter.

[0044] Thus, food serving articles provided in accordance with the present disclosure exhibit excellent resistance to water and oil absorption, generally comparable to substrates coated with non-biodegradable polymers such as polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET), while the coated substrate remains biodegradable.

[0045] In particular, according to some embodiments, the coating preferably exhibits a Cobb Water Absorption Value of less than 25 grams per square meter as measured according to TAPPI standard T 441. In more particular embodiments, the coating preferably exhibits a Kit Test Oil Resistance Value of greater than Kit Value 5 as measured according to TAPPI standard T 559 cm-12.

[0046] In a second aspect, the disclosure provides a method of making a biodegradable food serving article. Generally, the method includes the step of providing a biodegradable aqueous dispersion. The method also includes the step of forming a layer of the aqueous slurry on a mold. The aqueous slurry is then shaped using a combination of heat and pressure, such that the heat and pressure from the shaping dries the slurry to form a biodegradable substrate.

[0047] A quantity of the biodegradable aqueous dispersion is also applied to a substrate to form a layer of the dispersion, which is cured to form a film coating on the first surface of the biodegradable substrate.

[0048] A variety of methods can be used to cure the dispersion and form the film coating layer. For example, the substrate (with the applied dispersion layer) can be placed back into the mold and subjected to further heat and pressure. The heat and pressure of the mold can be used to cure the dispersion and simultaneously further dry the substrate.

[0049] In another example, the substrate (with the dispersion layer applied thereto) can be placed in a heated tunnel or oven for a period of time such that hot air in the tunnel or oven cures the dispersion. In yet another example, the dispersion layer can be subjected to infrared or other radiation to cure.

[0050] The biodegradable aqueous dispersion comprises at least water and at least one biodegradable polymer. Preferably, the dispersion also comprises further additives, such as surfactants, rheology modifiers, antifoaming agents, fillers, and / or biocides. In one preferred embodiment, the aqueous dispersion comprises about 40 weight percent to about 75 weight percent of at least one biodegradable polymer, about 0.1 weight percent to about 2.0 weight percent of surfactants, about 0.1 weight percent to about 2.0 weight percent of rheology modifiers, and about 0.001 weight percent to about 2.0 weight percent of at least one biocide.

[0051] As discussed above, it is preferred that the at least one biodegradable polymer is selected from the group consisting of polyhydroxyalkanoates, polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and mixtures thereof. More preferably, the biodegradable polymer comprises one or more polyhydroxyalkanoates, such as poly-3-hydroxybutyrate-co-3-hydroxyhexanoate, i.e., P(3HB-co-3HHx).

[0052] According to the present disclosure, the dispersions can be prepared using a variety of conventional mixing techniques. Preferably, the dispersions are mixed using high or low shear mixers and / or ultrasonic mixers.

[0053] According to the present disclosure, a layer of an aqueous slurry is formed on the former. The aqueous slurry includes water and about 10 weight percent to about 70 weight percent (preferably about 10 weight percent to about 60 weight percent) cellulose fiber. In some cases, the cellulose fiber in the slurry can include fiber derived from sugar cane, bagasse, wheatgrass, or recycled wood pulp.

[0054] In certain embodiments, the slurry can also contain an amount of the aqueous dispersion. That is, the slurry can contain an amount of the biodegradable polymer as well as other additives contained in the dispersion, such as surfactants, rheology modifiers, antifoam agents, fillers, and / or biocides. In some cases, the aqueous slurry can contain about 10 weight percent to about 70 weight percent of the biodegradable aqueous dispersion. Overall, the aqueous slurry has a solids content of about 10 weight percent to about 85 weight percent when initially formed on the mold.

[0055] Once the slurry layer is formed, the mold is closed and the slurry is then molded using a combination of heat and pressure. In some cases, it is preferred that the slurry is molded at a temperature of about 85° C. to about 170° C. and a pressure of about 100 psi to about 1500 psi. In other preferred embodiments, the pressure is about 1000 psi to about 100,000 psi. As this heat and pressure are applied during molding, the slurry at least partially dries to form a biodegradable substrate. After molding and associated drying are complete, the mold is opened and the substrate is removed.

[0056] Once the substrate is formed and at least partially dried, a layer of the biodegradable aqueous dispersion is applied onto the substrate. The dispersion may be applied onto the slurry in a variety of ways in accordance with the present disclosure, but is most preferably spray-applied onto at least one surface of the formed substrate. Preferably, the aqueous dispersion has a solids content of about 25 weight percent to about 60 weight percent, more preferably about 25 weight percent to about 55 weight percent, when initially sprayed or otherwise applied onto the substrate.

[0057] The aqueous dispersion is then cured and dried to form a film coating on the first surface of the biodegradable substrate, thus forming the finished food serving article. In some cases, the fully cured coating can be comprised of about 80 to 99.9 weight percent of at least one biodegradable polymer.

[0058] As discussed above, the food serving articles so provided exhibit excellent resistance to water and oil absorption, generally comparable to food serving articles coated with non-biodegradable polymers such as polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET), and further, the coated food serving articles of the present disclosure remain biodegradable. EXAMPLES

[0059] The following non-limiting examples illustrate various additional aspects of the present invention. Unless otherwise stated, temperatures are in degrees Celsius and percentages are by weight based on the dry weight of the formulation.

[0060] Examples 1-11: Preparation of aqueous dispersions EXAMPLES

[0061] In this example, an aqueous dispersion was prepared for spraying onto cellulose molded articles. 25-45% PHA (6.7 mol % polyhydroxyhexanoate; M w A white dispersion of 0.1 to 1.0% xanthan gum was then added to the resulting white dispersion and further sheared at 400 RPM for 30 minutes. Finally, 0.01 to 0.5% biocide was added to the dispersion. EXAMPLES

[0062] A dispersion was prepared as given in Example 1. 0.1 to 1.5% dispersant (DISPERBYK family) and then 0.01 to 1.0% rheology modifier (BYK400 family) were added to the dispersion and sheared to ensure uniform mixing. EXAMPLES

[0063] Dispersions were prepared as given in Example 2 and then 2.0 to 8% clay (Imersys Talc) was added and sheared to a uniform dispersion. EXAMPLES

[0064] In this example, 35.0 to 50% PHA (6.7 mol % polyhydroxyhexanoate M w A white dispersion of 0.01 to 1.5% xanthan gum was added to the resulting white dispersion and further sheared at 400 RPM for 30 minutes. Finally, 0.01 to 0.75% biocide was added to the dispersion. EXAMPLES

[0065] A dispersion was prepared as given in Example 4. 0.5 to 2.5% dispersant (DISPERBYK family) and then 0.01 to 1.0% rheology modifier (BYK400 family) were added to the dispersion and sheared to ensure uniform mixing. EXAMPLES

[0066] Dispersions were prepared as given in Example 5 and 5-15% kaolin clay was added and sheared to a uniform dispersion. EXAMPLES

[0067] In this example, 25 to 45% PHA (6.0 mol % polyhydroxyhexanoate M wA white dispersion of 0.01 to 1.0% xanthan gum was added to the resulting white dispersion and further sheared at 400 RPM for 30 minutes. Finally, 0.01 to 0.75% biocide was added to the dispersion. EXAMPLES

[0068] Dispersions were prepared as given in Example 7 and 5-15% kaolin clay was added and sheared to a uniform dispersion. EXAMPLES

[0069] In this example, 20-40% PHA (9.3 mol % polyhydroxyhexanoate M w A white dispersion of 0.01 to 0.75% xanthan gum was added to the resulting white dispersion and further sheared at 400 RPM for 30 minutes. Finally, 0.01 to 0.75% biocide was added to the dispersion. EXAMPLES

[0070] Dispersions were prepared as given in Example 9 and then 0.1 to 1.5% of a dispersant (DISPERBYK family) was added and sheared to ensure uniform mixing. EXAMPLES

[0071] A dispersion was prepared as given in Example 10 and then 1.0 to 10.0% PHA (28.3 mole % polyhydroxyhexanoate) was added and sheared to a uniform dispersion. EXAMPLES

[0072] In this example, 45.0 g of PHA (6.7 mol % hydroxyhexanoate M w A 0.25g Alcogum emulsion (0.3g / mol) was added to the resulting white dispersion and further sheared at 700 RPM for 5 minutes. Finally, 0.3 percent antifoam and 0.1% biocide were added to the dispersion. EXAMPLES

[0073] A dispersion was prepared as given in Example 12. 1 mL of dispersant (Tego 761) and then 0.1 mL of rheology modifier (Alcogum) were added to the dispersion and sheared to ensure uniform mixing. EXAMPLES

[0074] A dispersion was prepared as given in Example 14 and then 10 g of kaolin clay was added and sheared to a uniform dispersion. EXAMPLES

[0075] In this example, 30.0 g of PHA (9.3 mol % hydroxyhexanoate M w A 0.05g xanthan gum was added to the resulting white dispersion and further sheared at 400 RPM for 30 minutes. Finally, 0.1% biocide was added to the dispersion. EXAMPLES

[0076] The dispersion was prepared as given in Example 15 and then 0.75 mL of dispersant (Tego 755) was added and sheared to ensure uniform mixing. EXAMPLES

[0077] A dispersion was prepared as given in Example 16 and then 5.0 g of PHA (28.3 mole % hydroxyhexanoate) was added and sheared to a uniform dispersion. EXAMPLES

[0078] In this example, 55.0 g of PHA (6.7 mol % hydroxyhexanoate M w A 0.1 g xanthan gum and then 0.25 g alko gum were added to the resulting white dispersion and further sheared at 400 RPM for 3 minutes. Finally, 0.2% antifoam and 0.1% biocide were added to the dispersion. EXAMPLES

[0079] The dispersion was prepared as given in Example 18 and then 0.75 mL of dispersant (Tego 761) and 1.0 mL of rheology modifier were added and sheared to ensure uniform mixing.

[0080] Examples 20-21: Preparation and testing of coated substrates EXAMPLES

[0081] Each of the aqueous dispersions from Examples 1, 4, 7, 10, 13, 14, 16, and 17 were coated onto molded fiber trays using a variety of spray techniques. The coatings were cured in a hot air oven at 170° C. and applied at dry coat weights of 5-25 grams per square meter (gsm). Each of these dispersions achieved Cobb Water Absorption values ​​of less than 30 gsm, kit oil resistance values ​​of greater than 5, and no stain after 30 minutes with canola oil. EXAMPLES

[0082] Each of the aqueous dispersions from Examples 2, 5, 9, 12, 15, and 18 were coated onto molded fiber trays using a variety of spray techniques. The coatings were cured in a hot air oven at 170° C. and applied at dry coat weights of 10-25 grams per square meter (gsm). Cobb Water Absorption Values ​​obtained for each of these dispersions were less than 30 gsm, Kit Oil Resistance Values ​​were greater than 5, and canola oil was stain-free after 30 minutes.

[0083] The foregoing descriptions of preferred embodiments of the present invention have been presented for purposes of illustration. 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 to provide the best explanation of the principles of the invention and its practical application, thus enabling those skilled in the art to utilize the invention in various embodiments, and with various modifications, as suited to the particular uses contemplated. All such modifications and variations are within the scope of the invention, as defined in the appended claims, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. 1. A biodegradable food serving article comprising: a biodegradable substrate having at least one food contact surface comprising cellulose fibers; and a coating applied to at least one food contact surface comprising 25 weight percent to 60 weight percent of a polyhydroxyalkanoate; comprising A biodegradable substrate is formed from cellulose fibers and an aqueous slurry containing 10 to 70 weight percent of a biodegradable aqueous dispersion; the biodegradable aqueous dispersion comprises 25 to 60 weight percent polyhydroxyalkanoate; The biodegradable food supply article.

2. 10. The biodegradable food serving article of claim 1, wherein the polyhydroxyalkanoate has a weight average molecular weight of 50,000 to 2.5 million Daltons.

3. 10. The biodegradable food serving article of claim 1, wherein the biodegradable substrate comprises a biodegradable plate, cup, bowl, take-out container, straw or dishware.

4. 10. The biodegradable food serving article of claim 1, wherein at least a portion of the cellulose fibers are derived from sugar cane, bagasse, wheatgrass, or recycled wood pulp.

5. 10. The biodegradable food serving article of claim 1, wherein the coating is provided on at least one food contact surface at a dry basis application weight of from 5 to 50 grams per square meter.

6. 10. The biodegradable food serving article of claim 1, wherein the coating exhibits a Cobb Water Absorption Value of less than 25 grams per square meter, measured according to TAPPI standard T441.

7. 10. The biodegradable food serving article of claim 1, wherein the coating exhibits a kit test oil resistance value of greater than kit value 5, measured according to TAPPI standard T559 cm-12.

8. 1. A method of making a biodegradable food serving article, comprising: providing a biodegradable aqueous dispersion comprising water, 25 to 60 weight percent of at least one biodegradable polymer, 0.1 to 2.0 weight percent of a surfactant, 0.1 to 2.0 weight percent of a rheology control agent, optionally 0.1 to 1.0 percent of an antifoam agent, optionally 1 to 20% of a filler, and 0.001 to 2.0 weight percent of at least one biocide; forming a layer of an aqueous slurry on the former, the aqueous slurry comprising water and 10 weight percent to 60 weight percent cellulose fiber and 10 weight percent to 70 weight percent of a biodegradable aqueous dispersion; forming the aqueous slurry using a combination of heat and pressure, where the heat and pressure from the forming process dries at least a portion of the slurry to form a biodegradable substrate; providing a quantity of the biodegradable aqueous dispersion onto a substrate to form a layer of the dispersion on a first surface of the substrate; and curing the layer of dispersion to form a film coating on the first side of the biodegradable substrate; The method comprises the steps of: At least one biodegradable polymer comprises a polyhydroxyalkanoate; The method.

9. The method of claim 8, wherein the aqueous dispersion is spray coated onto at least one surface of the formed slurry layer.

10. 9. The method of claim 8, wherein the slurry is compacted at a temperature of from 85° C. to 170° C. and a pressure of from 1000 psi to 100,000 psi.

11. 10. The method of claim 8, wherein the slurry when initially formed on the mold has a solids content of from 10 percent to 85 percent by weight.

12. 10. The method of claim 8, wherein the aqueous dispersion when applied onto the slurry layer has a solids content of from 25 to 60 percent by weight.