EP4673375A1

EP4673375A1 - Cellulose ester tray

Info

Publication number: EP4673375A1
Application number: EP24714361.3A
Authority: EP
Inventors: Thomas Joseph Pecorini; Michael Eugene Donelson; Gaurav AMARPURI; Aaron David GRILLS; Corey PITCHFORD; Nicola Anne HERNDON; James Collins Maine
Original assignee: Eastman Chemical Co
Current assignee: Eastman Chemical Co
Priority date: 2023-02-27
Filing date: 2024-02-27
Publication date: 2026-01-07
Also published as: MX2025010077A; AU2024228557A1; CN120731174A; JP2026509198A; CO2025012763A2; WO2024182333A1

Abstract

A foamed tray formed from 50 to 99 wt. % cellulose ester. The tray comprises at least one elongated reinforcing member that includes a primary reinforcing member that extending laterally across at least 20% of a width of the tray. The primary reinforcing member is positioned no more than 0.25 inches apart from a lateral centerline of the tray.

Description

CELLULOSE ESTER TRAY

BACKGROUND OF THE INVENTION

Many foam articles, such as food-packaging articles, are single-use items that are intended to be disposed of after use. One commercially important material used to make foam articles is polystyrene. However, polystyrene is neither compostable nor biodegradable. Moreover, some municipalities, states, and countries have enacted, or are considering enacting, bans on the use polystyrene-based foams. Thus, it would be desirable to find alternative materials for use in foam articles, as well as viable compositions, methods, and systems for producing such articles.

SUMMARY OF THE INVENTION

In one embodiment or in combination with any other embodiment mentioned herein, there is provided a foamed tray formed from 50 to 99 wt. % cellulose ester. The tray comprises at least one elongated reinforcing member that includes a primary reinforcing member extending laterally across at least 20% of a width of the tray. The primary reinforcing member is positioned no more than 0.25 inches apart from a lateral centerline of the tray.

In another embodiment or in combination with any other embodiment mentioned herein, there is provided a process for making a foamed tray. The process comprises extruding a mixed composition comprising cellulose ester to form a foamed sheet. Cellulose ester is present in the mixed composition in an amount from about 50 wt. % to about 99 wt. %. An additional step includes thermoforming the foamed sheet to form the foamed tray. The tray comprises at least one elongated reinforcing member that includes a primary reinforcing member extending laterally across at least 20% of a width of the tray. The primary reinforcing member is positioned no more than 0.25 inches apart from a lateral centerline of tray. BRIEF DESCRIPTION OF THE DRAWINGS

Figure (FIG.) 1 is a schematic diagram illustrating a biodegradable article forming process according to embodiments of the present invention;

FIG. 2 is a schematic diagram illustrating another biodegradable article forming process according to embodiments of the present invention;

FIG. 3 is a schematic diagram illustrating an extrusion section that may be used in the article forming processes of FIGS. 1 and/or 2, according to embodiments of the present invention;

FIG. 4 is a schematic diagram illustrating another extrusion section that may be used in the article forming process of FIGS. 1 and 2, according to embodiments of the present invention;

FIG. 5 is a schematic diagram illustrating a sheet forming section that may be used in the article forming processes of FIGS. 1 and/or 2, according to embodiments of the present invention;

FIG. 6 is a perspective view of a foamed tray formed according to embodiments of the present invention, with the foamed tray including a plurality of three laterally-extending reinforcing members;

FIG. 7 is a top plan view of a foamed tray formed according to embodiments of the present invention, with the foamed tray not including reinforcing members;

FIG. 8 is a perspective view of a foamed tray formed according to embodiments of the present invention, with the foamed tray including a plurality of five laterally-extending reinforcing members,

FIG. 9 is a perspective view of a foamed tray formed according to embodiments of the present invention, with the foamed tray including a plurality of reinforcing members including a laterally-extending reinforcing member, diagonally-extending reinforcing members, and circularly-shaped reinforcing members;

FIG. 10 is a perspective view of a foamed tray formed according to embodiments of the present invention, with the foamed tray including a plurality of four edge reinforcing members; FIG. 1 1 is a perspective view of a foamed tray formed according to embodiments of the present invention, with the foamed tray including a plurality of ten edge reinforcing members; and

FIG. 12 is a perspective view of a foamed tray formed according to embodiments of the present invention, with the foamed tray including a plurality of ten edge and corner reinforcing members.

DETAILED DESCRIPTION

Embodiments are generally directed to methods, systems, and compositions for forming biodegradable particulate materials (e.g., pellets), foam sheets, and articles. Exemplary processes including the methods, systems, and compositions are depicted in FIGS. 1 - 5 and are described in greater detail below.

Methods and Systems

As shown in FIG. 1 and FIG. 2, raw materials may be introduced to a biodegradable polymer production process, which produces a biodegradable polymer material. In one embodiment or in combination with any other embodiment mentioned herein, the biodegradable polymer material comprises one or more cellulose esters. The one or more cellulose esters may comprise cellulose acetates. In such embodiments, the raw materials may comprise a pulp, such as wood pulp and/or cotton pulp. The pulp may be a dissolvinggrade pulp and/or a paper-grade pulp. The cellulose in the pulp may esterified, for example with an acetic acid, to form the biodegradable cellulose ester polymer, such as a cellulose acetate polymer.

The biodegradable polymer material may then be introduced into a compounding process, in which the biodegradable polymer material may be mixed with plasticizer, and optionally one or more other additives (e.g., stabilizers), and formed into a compounded material comprising plasticized biodegradable polymer. Other additives may also be mixed with the polymer and plasticizer. For example, as shown in FIG. 2, the other materials (additives) may include, but are not limited to, stabilizers, physical blowing agent(s), chemical blowing agent(s) (and/or precursors), nucleating agent(s), surface modifying additive(s), pigment(s), filler(s), and/or other additive(s). Mixing can be accomplished by any known mixing technique, including, but not limited to, rolling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling.

The compounding process may include a particulating process. The particulating process may generally comprise mixing the biodegradable polymer material, plasticizer, and other additive(s) to form a mixed composition and forming particulate material from the composition. In particular, the particulating process may include a pelletization process, and the particulate material may comprise a quantity of pellets. The term “compounded CE material” means cellulose ester material formed during the compounding process, which may include a mixture of cellulose ester, plasticizer, and other additives. Further such compounded CE material may be in the form of particulate material or pellets. It should be understood that, as used herein, the phrases “particulating” or “particulating processes” may be the same as, or may at least include, “pelletizing” or “pelletizing processes.” In some embodiments, the particulating process may include pelletizing into a water bath, pelletizing on an air cooled belt, underwater pelletizing, solvent compounding, etc.

In one embodiment or in combination with any other embodiment mentioned herein, the plasticizer and other additive(s) may be mixed with cellulose esters by conventional melt compounding techniques, which involve combining the cellulose ester with plasticizer, and optionally the other additives, in a twin screw extruder with appropriate mixing elements and at appropriate temperatures and pressures to achieve a molten, homogeneously combined, cellulose ester mixture by the time the materials exit the extruder. The molten, compounded, cellulose ester mixture may then be extruded through a die with orifices that are about 2-6 mm in diameter so as to extrude a strand. This strand may then be cooled by water (e.g., via underwater pelletization) or air and cut at regular intervals to provide a uniform and desirable size and shape, referred to as “pellets” or “granules.” Although a process for forming pelletized compounded material is described herein, it will be understood that the compounded material fed to the foam sheet production process can be in any physical shape (e.g., pellets, powders, granules, fibers) in accordance with some embodiments. The term “compounded CE material” means cellulose ester material formed during the compounding process, which may include a mixture of cellulose ester, plasticizer, and other additives. Further such compounded CE material may be in the form of a molten mixture or a particulate material (e.g., pellets, powders, granules, fibers, etc.)

The compounded CE material, which as noted above may comprise pellets of plasticized biodegradable polymer, may then be introduced into a foam sheet production process, as illustrated in FIGS. 1 and 2. The foam sheet production process may include one or more zones/steps for producing a foam sheet or film, which are described in greater detail below. Although an exemplary foam sheet production process is described herein, it should be understood that certain aspects described herein may also be applicable to rigid (i.e., non-foamed) materials and articles. As shown in FIG. 1 , in one embodiment or in combination with any other embodiment mentioned herein, various additives may be introduced to one or more zones of the foam sheet production process. The additives may include, but are not limited to, stabilizers, physical blowing agent(s), chemical blowing agent(s) (and/or precursors), nucleating agent(s), surface modifying additive(s), pigment(s), filler(s), and/or other additive(s).

The foam sheet production process may generally include an extrusion section and a sheet forming section. An exemplary extrusion section is depicted in FIG. 3. As shown, the extrusion section may comprise a feed preparation zone, in which solid additives may be combined with the compounded CE material and introduced to the downstream extrusion zone. In one embodiment or in combination with any other embodiment mentioned herein, the feed preparation zone may comprise a feed hopper. Thus, the compounded CE material and the other solid additives may be deposited into the feed hopper, which directs the combined feed composition into the extrusion zone. The feed preparation zone may further comprise a mixer, in which the compounded CE material and one or more additive(s) may be mixed before being introduced to the hopper. Mixing can be accomplished by any known mixing technique, including, but not limited to, rolling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling. Exemplary solid additive(s) that can be combined with the compounded material may include chemical blowing agent(s), nucleating agent(s), surface modifying additive(s), pigment(s), filler(s), and/or other additive(s).

The combined feed composition from the feed preparation zone may then be introduction to the extrusion zone. The extrusion zone may generally comprise one or more extruders, which may include single screw and/or twin screw extruders. Within the extruder(s), the feed composition may be introduced into an extruder barrel and conveyed, via the screw(s), through a die, which forms an extrudate from the feed composition. The composition may be heated, and at least partially melted, as it is conveyed through the extruder barrel toward the die. Thus, the term “CE melt composition” is used herein to mean the cellulose ester-based feed composition that has been melted into a flowable, molten resin via the extrusion section. Heating may be supplied by external heaters positioned along the outside of the extruder barrel. The shape of the extrudate will generally depend on the shape and size of the die head. The extrudate may be further shaped by downstream processes, as described below.

One or more additive(s) may be introduced to the CE melt resin while in the extruder. For example, one or more physical blowing agent(s) may be added to the CE melt resin by injecting the physical blowing agent into the composition being conveyed within the extruder barrel.

As depicted in FIG. 4, in one embodiment or in combination with any other embodiment mentioned herein, the extrusion zone may comprise a primary extrusion vessel and a cooling vessel. The primary extrusion vessel and cooling vessel may be separate devices or combined as a unitary apparatus. Regardless, the feed composition from the feed preparation zone is introduced into the primary extrusion vessel and at least partially melted as it is conveyed through the extruder barrel, as described above, to thereby produce the CE melt resin. The CE melt resin exiting the primary extrusion vessel may have a temperature from about 220° C to about 240° C. One or more additives, such as blowing agent(s), may be added to the CE melt resin as it is conveyed through the primary extrusion vessel.

The CE melt resin from the primary extrusion vessel is then introduced into the cooling vessel. The cooling vessel may be a secondary extrusion vessel, which operates similarly to, but at a lower temperature than, the primary extrusion vessel. Within the cooling vessel, the CE melt resin may be further mixed to provide a substantially homogenous mixture of the melted polymer and other additive(s). The CE melt resin may then be directed through the die and out of the die head to provide a cellulose ester-based extrudate, which may be further processed in the sheet forming section of the foam sheet production process. In one embodiment or in combination with any other embodiment mentioned herein, the CE melt resin exiting the die head may have a temperature of at least 150° C, at least 160° C, at least 170° C, at least 180° C, at least 190° C, at least 200° C, from about 150° C to about 220° C, and/or from about 170° C to about 200° C.

As shown in FIG. 4, one or more filtration devices may be installed within the extrusion section to filter and remove particulate matter from the CE melt resin. For example, screen changer filtration devices may be installed at the downstream end of the primary and secondary extrusion vessels, which may remove solid components from the CE melt resin before directing the CE melt resin through the die head to the sheet forming section.

The sheet forming section may include any of a variety of systems and processes for shaping the extrudate into sheets of cellulose ester material that may be used in article formation. The shape of the extrudate will generally depend on the shape of the die head, while the shape of the sheets formed in the sheet forming section can depend on the shape of the die head and other downstream processes. For example, the extrudate may have a generally flat shape, or it may be annular and subjected to further processing to form a flat sheet. In embodiments in which the die has an annular shape, the die may have a diameter from 1 to 40 cm, from 2 to 20 cm, 2 to 10 cm, and/or 3 to 8 cm. Furthermore, the thickness of the opening from which extrudate is ejected, which is referred to herein as a “die gap,” may generally be sized from 0.1 to 6.0 mm, from 0.1 to 3.0 mm, and/or from 0.1 to 1.0 mm.

An exemplary sheet forming section is depicted in FIG. 5. As shown, the CE melt resin is extruded through an annular die and drawn over a forming mandrel. A cooling fluid (e.g., air) may be flowed across the interior and/or exterior of the extrudate to cool the extrudate material as it passes over the mandrel. For example, the cooling fluid may be blown from the mandrel toward the die to cool the interior surface of the extrudate between the die and mandrel. Additionally or alternative, the cooling fluid may be flowed across the mandrel to cool the exterior surface of the extrudate as it passes over the mandrel.

A slicer (or slitting device) may be used to open the tubular extrudate, which allows the tubular shape to be formed into a flat sheet. For example, the tubular extrudate passing over the mandrel may be slit and drawn to a tensioning station comprising one or more rollers that flatten the extrudate and maintain a necessary amount of tension on the extrudate to continue pulling the extrudate over the mandrel. The flattened extrudate will generally be in the form of a sheet, which may then be directed to a winding station where the material may be rolled for packaging and transportation.

Referring again to FIG. 1 and FIG. 2, the sheets produced by the sheet production process may be used to form foam articles, which are described in greater detail below. Such articles are particularly useful in the food service industry. Exemplary articles include meat trays. The articles may have one or more particularly advantageous properties. For example, the articles may be biodegradable and/or compostable, and/or the articles may have superior mechanical properties (e.g., strength, density, cell size, absorption, etc.). Compositions

The processes described above may comprise the preparation and extrusion of compositions that may be used for downstream processing to form useful articles. For example, in one embodiment or in combination with any other embodiment mentioned herein, the extrusion feed material may comprise a particulate material comprising a biodegradable polymer, a plasticizer, and optionally one or more additive(s), such as those described herein. In one embodiment or in combination with any other embodiment mentioned herein, the feed material may be combined with one or more additive(s), such as those described herein, to provide a mixed composition comprising the biodegradable polymer, the plasticizer, and the one or more additive(s). In one embodiment or in combination with any other embodiment mentioned herein, the biodegradable polymer comprises cellulose ester. Additional details of the composition components, including biodegradable polymers (e.g., cellulose esters), plasticizers, and other additives, are provided below.

Cellulose Ester

The cellulose esters utilized as described herein can be any that is known in the art. Cellulose ester that can be used for embodiments herein generally comprise repeating units of the structure:

1 2 2 wherein R ¹ , R , and R are selected independently from the group consisting of hydrogen acetyl, propyl or butyl. The substitution level of the cellulose ester is usually expressed in terms of degree of substitution (DS), which is the average number of non-OH substituents per anhydroglucose unit (AGU). Generally, conventional cellulose contains three hydroxyl groups in each AGU unit that can be substituted; therefore, DS can have a value between zero and three. Native cellulose is a large polysaccharide with a degree of polymerization from 250 - 5,000 even after pulping and purification, and thus the assumption that the maximum DS is 3.0 is approximately correct. Because DS is a statistical mean value, a value of 1 does not assure that every AGU has a single substitutent. In some cases, there can be unsubstituted anhydroglucose units, some with two and some with three substitutents, and typically the value will be a non-integer. Total DS is defined as the average number of all of substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to a particular substitutent, such as, for example, hydroxyl or acetyl. In one embodiment or in combination with any other embodiment, n is an integer in a range from 25 to 250, or 25 to 200, or 25 to 150, or 25 to 100, or 25 to 75.

In one embodiment or in combination with any other embodiment, the cellulose esters have at least 2 anhydroglucose rings and can have between at least 50 and up to 5,000 anhydroglucose rings, or at least 50 and less than 150 anhydroglucose rings. The number of anhydroglucose units per molecule is defined as the degree of polymerization (DP) of the cellulose ester. In one embodiment or in combination with any other embodiment, cellulose esters can have an inherent viscosity (IV) of about 0.2 to about 3.0 deciliters/gram, or about 0.5 to about 1 .8, or about 1 to about 1 .5, as measured at a temperature of 25°C for a 0.25 gram sample in 100 ml of a 60/40 by weight solution of phenol/tetrachloroethane. In one embodiment or in combination with any other embodiment, cellulose esters useful herein can have a DS/AGU of about 1 to about 3.0, of about 2.2 to about 2.8, or 1 to less than 2.2, or 1 to less than 1 .5, and the substituting ester is acetyl.

Cellulose esters can be produced by any method known in the art. Examples of processes for producing cellulose esters are taught in Kirk- Othmer, Encyclopedia of Chemical Technology, 5th Edition, Vol. 5, Wiley- Interscience, New York (2004), pp. 394-444. Cellulose, the starting material for producing cellulose esters, can be obtained in different grades and sources such as from cotton linters, softwood pulp, hardwood pulp, corn fiber and other agricultural sources, and bacterial cellulose, among others.

One method of producing cellulose esters is esterification of the cellulose by mixing cellulose with the appropriate organic acids, acid anhydrides, and catalysts. Cellulose is then converted to a cellulose triester. Ester hydrolysis is then performed by adding a water-acid mixture to the cellulose triester, which can then be filtered to remove any gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester can then be washed with water to remove reaction byproducts followed by dewatering and drying.

The cellulose triesters to be hydrolyzed can have three acetyl substituents. These cellulose esters can be prepared by a number of methods known to those skilled in the art. For example, cellulose esters can be prepared by heterogeneous acylation of cellulose in a mixture of carboxylic acid and anhydride in the presence of a catalyst such as H2SO4. Cellulose triesters can also be prepared by the homogeneous acylation of cellulose dissolved in an appropriate solvent such as LiCI/DMAc or LiCI/NMP.

Those skilled in the art will understand that the commercial term of cellulose triesters also encompasses cellulose esters that are not completely substituted with acyl groups. For example, cellulose triacetate commercially available from Eastman Chemical Company, Kingsport, TN, U.S.A., typically has a DS from about 2.85 to about 2.99.

After esterification of the cellulose to the triester, part of the acyl substituents can be removed by hydrolysis or by alcoholysis to give a secondary cellulose ester. As noted previously, depending on the particular method employed, the distribution of the acyl substituents can be random or non-random. Secondary cellulose esters can also be prepared directly with no hydrolysis by using a limiting amount of acylating reagent. This process is particularly useful when the reaction is conducted in a solvent that will dissolve cellulose. All of these methods yield cellulose esters that are useful in this invention.

In one embodiment or in combination with any of the mentioned embodiments, the cellulose acetates are cellulose diacetates that have a polystyrene equivalent number average molecular weight (Mn) from about 10,000 to about 100,000 as measured by gel permeation chromatography (GPC) using NMP as solvent and polystyrene equivalent Mn according to ASTM D6474. In one embodiment or in combination with any other embodiment, the cellulose acetate composition comprises cellulose diacetate having a polystyrene equivalent number average molecular weights (Mn) from 10,000 to 90,000; or 10,000 to 80,000; or 10,000 to 70,000; or 10,000 to 60,000; or 10,000 to less than 60,000; or 10,000 to less than 55,000; or 10,000 to 50,000; or 10,000 to less than 50,000; or 10,000 to less than 45,000; or 10,000 to 40,000; or 10,000 to 30,000; or 20,000 to less than 60,000; or 20,000 to less than 55,000; or 20,000 to 50,000; or 20,000 to less than 50,000; or 20,000 to less than 45,000; or 20,000 to 40,000; or 20,000 to 35,000; or 20,000 to 30,000; or 30,000 to less than 60,000; or 30,000 to less than 55,000; or 30,000 to 50,000; or 30,000 to less than 50,000; or 30,000 to less than 45,000; or 30,000 to 40,000; or 30,000 to 35,000; as measured by gel permeation chromatography (GPC) using NMP as solvent and according to ASTM D6474.

The most common commercial secondary cellulose esters are prepared by initial acid catalyzed heterogeneous acylation of cellulose to form the cellulose triester. After a homogeneous solution in the corresponding carboxylic acid of the cellulose triester is obtained, the cellulose triester is then subjected to hydrolysis until the desired degree of substitution is obtained. After isolation, a random secondary cellulose ester is obtained. That is, the relative degree of substitution (RDS) at each hydroxyl is roughly equal.

The cellulose esters useful in the present invention can be prepared using techniques known in the art, and can be chosen from various types of cellulose esters, such as for example the cellulose esters that can be obtained from Eastman Chemical Company, Kingsport, TN, U.S.A., e.g., Eastman™ Cellulose Acetate CA 398-30 and Eastman™ Cellulose Acetate CA 398-10, Eastman™ CAP 485-20 cellulose acetate propionate; Eastman™ CAB 381-2 cellulose acetate butyrate.

In one embodiment or in combination with any other embodiment, the cellulose ester can be prepared by converting cellulose to a cellulose ester with reactants that are obtained from recycled materials, e.g., a recycled plastic content syngas source. In one embodiment or in combination with any other embodiment, such reactants can be cellulose reactants that include organic acids and/or acid anhydrides used in the esterification or acylation reactions of the cellulose, e.g., as discussed herein.

In one embodiment or in combination with any of the mentioned embodiments, or in combination with any of the mentioned embodiments, of the invention, a cellulose ester composition comprising at least one recycle cellulose ester is provided, wherein the cellulose ester has at least one substituent on an anhydroglucose unit (AU) derived from recycled content material, e.g., recycled plastic content syngas.

In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises cellulose ester in an amount from 50 to 99 wt%, or 60 to 99 wt%, or 70 to 99 wt%, or 80 to 99 wt%, or 90 to 99 wt%, 50 to 90 wt%, or 60 to 90 wt%, or 70 to 90 wt%, or 80 to 90 wt%, or 90 to 99 wt%, or 50 to 80 wt%, or 60 to 80 wt%, or 70 to 80 wt%, or 50 to 70 wt%, or 60 to 70 wt%, or 50 to 60 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein may comprise a combination, blend, or mixture of two or more different types of cellulose esters. For example, in some embodiments, the cellulose esters used herein may be comprised of a blend of two or cellulose esters having differing DSACs; however, the blend may have an total DSAC of between 2.2 and 2.8

Plasticizer

In one embodiment or in combination with any other embodiment, the cellulose ester compositions described herein can comprise at least one plasticizer. The plasticizer reduces the melt temperature, i.e., the Tg, and/or the melt viscosity of the cellulose ester. Plasticizers for cellulose esters may include glycerol triacetate (Triacetin), glycerol diacetate (Diacetin), dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, polyethylene glycol) MW 200-600, dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl o- benzoylbenzoate, triethylene glycol dipropionate, 1 ,2-epoxypropylphenyl ethylene glycol, 1 ,2-epoxypropyl(m-cresyl) ethylene glycol, 1 ,2-epoxypropyl(o- cresyl) ethylene glycol, p-oxyethyl cyclohexenecarboxylate, bis(cyclohexanate) diethylene glycol, triethyl citrate, polyethylene glycol, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinyl pyrollidone, and glycol tribenzoate, the benzoate containing plasticizers such as the Benzoflex™ plasticizer series, poly (alkyl succinates) such as poly (butyl succinate), polyethersulfones, o-Cresyl p-toluenesulfonate, n- ethyltoluenesulfonamides, adipate based plasticizers, soybean oil epoxides such as the Paraplex™ plasticizer series, sucrose based plasticizers, dibutyl sebacate, tributyrin, sucrose acetate isobutyrate, the Resolflex™ series of plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (e.g., ethyl phthalyl ethyl glycolate “EPEG” and methyl phthalyl ethyl glycolate “MPEG”), methoxy polyethylene glycol, 2,2,4-trimethylpentane-1 ,3-diyl bis(2- methylpropanoate), and polycaprolactones. In some embodiments, the plasticizer used herein may comprise a combination or mixture of two or more different types of plasticizers.

In one embodiment or in combination with any other embodiment, the plasticizer is a food-compliant plasticizer. By food-compliant is meant compliant with applicable food additive and/or food contact regulations where the plasticizer is cleared for use or recognized as safe by at least one (national or regional) food safety regulatory agency (or organization), for example listed in the 21 CFR Food Additive Regulations or otherwise Generally Recognized as Safe (GRAS) by the US FDA. In one embodiment or in combination with any other embodiment, the food-compliant plasticizer is triacetin or polyethylene glycol (PEG) having a molecular weight of about 200 to about 600. In one embodiment or in combination with any other embodiment, examples of food-compliant plasticizers that could be considered can include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinyl pyrollidone, and glycol tribenzoate. In one embodiment or in combination with any other embodiment, the plasticizer can be present in an amount sufficient to permit the cellulose ester composition to be melt processed (or thermally formed) into useful articles, e.g., single use plastic articles, in conventional melt processing equipment. In one embodiment or in combination with any other embodiment, the plasticizer is present in an amount from 1 to 40 wt% for most thermoplastics processing; or 5 to 25 wt%, or 10 to 25 wt%, or 12 to 20 wt% based on the weight of the cellulose ester composition. In one embodiment or in combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be accomplished with plasticizer levels in the 10-30, or 12-25, or 15-20, or 10-25 wt% range, based on the weight of the cellulose ester composition.

In one embodiment or in combination with any other embodiment, the plasticizer is a biodegradable plasticizer. Some examples of biodegradable plasticizers include triacetin, triethyl citrate, acetyl triethyl citrate, polyethylene glycol, the benzoate containing plasticizers such as the Benzoflex™ plasticizer series, poly (alkyl succinates) such as poly (butyl succinate), polyethersulfones, adipate based plasticizers, soybean oil epoxides such as the Paraplex™ plasticizer series, sucrose based plasticizers, dibutyl sebacate, tributyrin, the Resoflex™ series of plasticizers, triphenyl phosphate, glycolates, polyethylene glycol, 2,2,4-trimethylpentane-1 ,3-diyl bis(2- methylpropanoate), and polycaprolactones.

In one embodiment or in combination with any other embodiment, the cellulose ester composition can contain a plasticizer selected from the group consisting of PEG and MPEG (methoxy PEG). The polyethylene glycol or a methoxy polyethylene glycol composition having an average molecular weight of from 200 Daltons to 600 Daltons, wherein the composition is melt processable, biodegradable, and disintegrable.

In one embodiment or in combination with any other embodiment, the composition comprises polyethylene glycol or methoxy PEG having an average molecular weight of from 300 to 550 Daltons. In one embodiment or in combination with any other embodiment, the composition comprises polyethylene glycol having an average molecular weight of from 300 to 500 Daltons.

In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises at least one plasticizer (as described herein) in an amount from 1 to 40 wt%, or 5 to 40 wt%, or 10 to 40 wt%, or 12 to 40 wt%, 13 to 40 wt%, or 15 to 40 wt%, or greater than 15 to 40 wt%, or 17 to 40 wt%, or 20 to 40 wt%, or 25 to 40 wt%, or 5 to 35 wt%, or 10 to 35 wt%, or 13 to 35 wt%, or 15 to 35 wt%, or greater than 15 to 35 wt%, or 17 to 35 wt%, or 20 to 35 wt%, or 5 to 30 wt%, or 10 to 30 wt%, or 13 to 30 wt%, or 15 to 30 wt%, or greater than 15 to 30 wt%, or 17 to 30 wt%, or 5 to 25 wt%, or 10 to 25 wt%, or 13 to 25 wt%, or 15 to 25 wt%, or greater than 15 to 25 wt%, or 17 to 25 wt%, or 5 to 20 wt%, or 10 to 20 wt%, or 13 to 20 wt%, or 15 to 20 wt%, or greater than 15 to 20 wt%, or 17 to 20 wt%, or 5 to 17 wt%, or 10 to 17 wt%, or 13 to 17 wt%, or 15 to 17 wt%, or greater than 15 to 17 wt%, or 5 to less than 17 wt%, or 10 to less than 17 wt%, or 13 to less than 17 wt%, or 15 to less than 17 wt%, all based on the total weight of the cellulose ester composition.

In one embodiment or in combination with any other embodiment, the at least one plasticizer includes or is a food-compliant or FDA approved plasticizer. In one embodiment or in combination with any other embodiment, the food-compliant or FDA approved plasticizer includes or is triacetin or PEG MW 300 to 500.

Biodegradable Polymers

In one embodiment or in combination with any other embodiment, the cellulose ester compositions described herein comprise a biodegradable cellulose ester (BCE) component that comprises at least one BCE, which may include one or more of the cellulose esters described herein, and a biodegradable polymer component that comprises at least one other biodegradable polymer (other than the BCE). In one embodiment or in combination with any other embodiment, the other biodegradable polymer can be chosen from polyhydroxyalkanoates (PHAs and PHBs), polylactic acid (PLA), polycaprolactone polymers (PCL), polybutylene adipate terephthalate (PBAT), polyethylene succinate (PES), polyvinyl acetates (PVAs), polybutylene succinate (PBS) and copolymers (such as polybutylene succinate-co-adipate (PBSA)), cellulose esters, cellulose ethers, starch, proteins, derivatives thereof, and combinations thereof. In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises two or more biodegradable polymers. In one embodiment or in combination with any other embodiment, the cellulose ester composition contains a biodegradable polymer (other than the BCE) in an amount from 0.1 to less than 50 wt%, or 1 to 40 wt%, or 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, based on the cellulose ester composition. In one embodiment or in combination with any other embodiment, the cellulose ester composition contains a biodegradable polymer (other than the BCE) in an amount from 0.1 to less than 50 wt%, or 1 to 40 wt%, or 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, based on the total amount of BCE and biodegradable polymer. In one embodiment or in combination with any other embodiment, the at least one biodegradable polymer comprises a PHA having a weight average molecular weight (Mw) in a range from 10,000 to 1 ,000,000, or 50,000 to 1 ,000,000, or 100,000 to 1 ,000,000, or 250,000 to 1 ,000,000, or 500,000 to 1 ,000,000, or 600,000 to 1 ,000,000, or 600,000 to 900,000, or 700,000 to 800,000, or 10,000 to 500,000, or 10,000 to 250,000, or 10,000 to 100,000, or 10,000 to 50,000, measured using gel permeation chromatography (GPC) with a refractive index detector and polystyrene standards employing a solvent of methylene chloride. In one embodiment or in combination with any other embodiment, the PHA can include a polyhydroxybutyrate-co- hydroxyhexanoate.

Nucleating Agent

Nucleating agent means a chemical or physical material that provides sites for cells to form in a molten formulation mixture, such as within a CE melt resin. As will be described in more detail below, nucleating agents may be added to compounded CE material during the compounding process. Alternatively, or in addition, nucleating agents may be added during the foam sheet production process. For example, the nucleating agents may be blended with the formulation that is introduced into the hopper of the extruder of the extruding section. Alternatively, the nucleating agents may be added to the CE melt resin in the extruder itself. Nucleating agents may include physical nucleating agents and chemical nucleating agents. Physical nucleating agents are materials that are immiscible with the polymer matrix of the CE melt resin at the extrusion temperature of the extrusion section. Chemical nucleating agents are materials that react (e.g., decompose) during extrusion (e.g., at the extrusion temperature within the extruder) to form physical nucleating agents. Thus, chemical nucleating agents may be considered (and referred to herein as) precursors of in situ formed physical nucleating agents.

Suitable physical nucleating agents will comprise fine particles having desirable particle sizes and/or shapes to create cell nucleation sites within the CE melt resin. For example, in some embodiments, physical nucleating agents will have a mean particle size of less than 1000 microns, less than 500 microns, less than 100 microns, less than 50 microns, less than 25 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 2 microns, less than 1.5 microns, and/or less than 1.0 microns. However, in some other embodiments, it may be preferred to have nanoscale-sized particles. Furthermore, it some embodiments, physical nucleating agents will preferably have a high aspect ratio (i.e., width:height). For example, in some embodiments, physical nucleating agents will have a mean aspect ratio of greater than 1 :1 , greater than 2:1 , greater than 5:1 , greater than 10:1 , greater than 20:1 , greater than 30:1 , greater than 40:1 , greater than 50:1 , greater than 75:1 , and/or greater than 100:1. Furthermore still, as noted above, physical nucleating agents should be immiscible with the polymer matrix of the CE melt resin at the extrusion temperature of the extrusion section. As such, in some embodiments, the physical nucleating agents should have a melting temperature at least 220° C, at least 230° C of at least 240° C, at least 250° C, at least 275° C, at least 300° C, at least 325° C, or at least 350° C. Nevertheless, the physical nucleating agents may be selected such that they have the ability to, after melting, recrystallize upon cooling.

Examples of suitable inorganic physical nucleating agents include, but are not limited to, minerals such as talc, CaCOs, mica, and mixtures of at least two of the foregoing. One representative example is Heritage Plastics HT6000 Linear Low Density Polyethylene (LLDPE) Based Talc Concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon oxide, titanium oxide, magnesium oxide, aluminum oxide and calcium silicate, barium sulfate, Kaolin, aluminum tryhydrate ATH (AI(OH)₃), MDH (Mg(OH)₂), Diatomaceous earth, magnetite/hematite, halloysite, zinc oxide, and titanium dioxide. In some embodiments, the inorganic nucleating agents will comprise oxides, such as metal oxides or mixed metal oxides, such as those selected from one or more of the following: aluminum oxide, antimony oxide, arsenic oxide, bismuth oxide, boron oxide, calcium oxide, gallium oxide, iron oxide, lithium oxide, magnesium oxide, silicon oxide, and titanium oxide. In other embodiments, the inorganic nucleating agents will comprise silicates, such as silicates selected from one or of the following: magnesium silicate and calcium silicate.

It has been discovered that biodegradable natural, particulate materials derived from renewable organic sources (e.g., organic nucleating agents) can also serve as effective physical nucleating agents. Natural materials that can be physical nucleating agents include material comprised of cellulose fibers and/or cellulose starch. Examples include, but are not limited to almond shell flour, animal fiber, apricot shell flour, bamboo flour, tree bark flour, clam shell flour, coconut shell flour, coconut coir, cork flour, corn cob flour, corn cob grit, cottonseed hulls, flock & fiber, hazelnut shell flour, kenaf flour, natural fibers, nutshell hull & flour, oat fiber powder, olive stone flour, peanut hulls flour, pecan shell flour, pine-nut shell powder, pistachio-nut shell flour, plant fiber, rice hull flour, rice hull grit, rice husk, soy bean flour, starch flour (hydrophobic), walnut shell flour, wheat chaff, wheat husk, and wood flour. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, stearic acid metal salts, carbon black, and dolomite.

As noted above, suitable chemical nucleating agents (or precursors of in situ formed physical nucleating agents) are configured to decompose to create cell nucleation sites in the CE melt resin when a threshold chemical reaction temperature is reached. These small cells act as nucleation sites for larger cell growth from a physical or other type of blowing agent. In some embodiments, the precursors are configured to form a gas during extrusion of the particulate material, such as CO2 or N2.

Examples of chemical nucleating agents include but are not limited to acids, such as citric acid or a citric acid-based material. Other acids may include lauric acid, stearic acid, tartaric acid, ascorbic acid, propionic acid, and hexanoic acid. One representative example is HYDROCEROL™ CF-40E (available from Clariant Corporation), which contains citric acid and a crystal nucleating agent. In some embodiments ,the chemical nucleating agents will include a combination of an acid and a base, such as a carbonate, which may include sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, etc. For instance, a representative example of a chemical nucleating agent is a combination of citric acid and sodium bicarbonate. In some embodiments, chemical nucleating agents may include a carrier within which the active components of the nucleating agents are dispersed. For example, yet another representative example of chemical nucleating agents is a combination of citric acid, sodium bicarbonate, and a carrier. In some embodiments, the carrier may comprise polystyrene. However, the carrier may comprise other compositions, such as various biopolymers (e.g., polybutylene succinate, Capa polyesters, etc.), polyolefins, acrylic copolymers (e.g., ethylene methyl acrylate), or the like. In some such embodiments, the citric acid and sodium bicarbonate may comprise about half (in wt%) of the chemical nucleating agents, while the carrier makes up the remaining half (in wt%). Furthermore, in some of such embodiments, there may be more sodium bicarbonate than citric acid in the chemical nucleating agent. For instance, there may be about three times as much (in wt%) sodium bicarbonate than citric acid in the chemical nucleating agent. It should also be understood that in some embodiments, no carrier may be required or used, such as the case with the nucleating agent being Hecofoam or HydroceroL

In one embodiment or in combination with any of the embodiments mentioned herein, the nucleating agents are present at from 0.1 to 10 wt%, from 0.1 to 5.0 wt%, at least 0.1 wt%, at least 0.25 wt%, at least 0.5 wt% at least 1 .0 wt%, at least 1 .25 wt%, at least 1 .5 wt%, at least 1 .75 wt%, at least 2.0 wt%, at least 2.25 wt%, at least 2.5 wt%, at least 2.75 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt% and/or less than 7.5 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 .0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agents used herein may comprise a combination or mixture of two or more different types of nucleating agents.

It is noted that the cellulose ester material, whether in the form of compounded CE material or CE melt resin, will generally be able to accept a maximum amount of nucleating agent that can function to form nucleation sites. Any remaining nucleating agent that is added to the cellulose ester material will remain as filler. Fillers can provide various properties to the resulting cellulose ester foams and/or articles based on the type of filler used. For example, some fillers can provide increased/decreased density, ductility, Young’s modulus, yield strength, heat deflection temperature, permeability, impact resistance, elongation to break, adhesion properties, biodegradation, etc. of the cellulose ester material. Fillers can also be used to alter the visual characteristics (e.g., color, opacity, etc.) and tactile characteristics (e.g., material continuous, surface roughness, etc.) of the cellulose ester material.

Blowing Agents

A blowing agent refers to a physical or a chemical material (or combination of materials) that acts to expand nucleation sites. Blowing agents may include chemical blowing agents, physical blowing agents, combinations thereof, or several types of chemical and physical blowing agents. The blowing agents function to reduce density of a material by expanding cells formed in the molten formulation at the nucleation sites. The blowing agent may be added to the CE melt resin in the extruder. It has been surprisingly discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture and carry the absorbed water into the molten resin mixture where the water can act as a physical blowing agent.

Examples of physical blowing agents include H₂O, N₂, CO₂, alkanes, alkenes, ethers, ketones, argon, helium, air or mixtures. In addition, it has been surprisingly discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture and carry the absorbed water into the molten resin mixture where the water can act as a physical blowing agent. Hygroscopic biodegradable natural fillers can be formulated into a composition and allowed to absorb moisture prior to the foaming process, where the water then is released to act as a physical blowing agent. Beneficially, the water may also be used as a plasticizer for the cellulose ester resin. Furthermore, in some embodiments, physical blowing agents may include hydrocarbons, such as pentane/isopentane or butane/isobutane. Other hydrocarbons may include propane, ethane, methane, hexane, cyclohexane, cyclopentane, cyclobutene, or the like.

Chemical blowing agents are materials that degrade or react to produce a gas (e.g., CO₂ or N₂). Such gasses expand the cells within the molten resin mixture and/or resulting foam mixture to produce a structural material with a plurality of gaseous voids dispersed throughout. Chemical blowing agents may be endothermic or exothermic. Chemical blowing agents typically degrade at a certain temperature to decompose and release gas. Examples of chemical blowing agents include azodicarbonamide, acids (e.g., citric acid), and carbonates, such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, and the like and combinations thereof.

In one embodiment or in combination with any of the embodiments mentioned herein, the blowing agent is present at from 0.3 to 1 .5 wt%, or 0.3 to 2.0 wt%, or 0.3 to 2.5 wt%, or 0.3 to 3.0 wt%, or 0.3 to 3.5 wt%, or 0.3 to 4.0 wt%, or 0.3 to 8%, or 1 .3 to 1 .5 wt%, or 1 .3 to 2.0 wt%, or 1 .3 to 2.5 wt%, or 1 .3 to 3.0 wt%, or 1 .3 to 3.5 wt%, or 1 .3 to 4.0 wt%, or 1 .3 to 4.5 wt%, or 1 .3 to 5.0 wt%, or 1 .3 to 5.5 wt%, or 1 .5 to 3.0 wt%, or 1 .5 to 4.0 wt%, or 1 .5 to 5.0 wt%, or 1 .5 to 6.0 wt%, or 2.0 to 3.0 wt%, or 2.0 to 4.0 wt%, or 2.0 to 5.0 wt%, or 2.0 to 6.0 wt%, or 2.5 to 3.0 wt%, or 2.5 to 4.0 wt%, or 2.5 to 5.0 wt%, or 2.5 to 6.0 wt%, or 3.0 to 4.0 wt%, or 3.0 to 5.0 wt%, or 3.0 to 6.0 wt%, or 0.0 to 9.0 wt%, or 0.5 to 9.0 wt%, or 1 .0 to 9.0 wt%, or 1 .5 to 9.0 wt%, or 2.0 to 9.0 wt%, or 2.5 to 9.0 wt%, or 3.0 to 9.0 wt%, or 3.5 to 9.0 wt%, or 4.0 to 9.0 wt%, or 4.5 to 9.0 wt%, or 5.0 to 9.0 wt%, or 5.5 to 9.0 wt%, or 6.0 to 9.0 wt%, or 6.5 to 9.0 wt%, or 7.0 to 9.0 wt%, or 7.5 to 9.0 wt%, or 8.0 to 9.0 wt%, or 8.5 to 9.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the blowing agents used herein may comprise a combination or mixture of two or more different types of blowing agents.

Surface Modifying Additives

Surface modifying additives refer to materials that can be added to cellulose ester compositions to modify the structure of the compositions (or the resulting foam articles) to improve processing of the cellulose ester compositions. For example, the inventors of the present application have found that adding surface modifying additives to the compounded CE material (e.g., to the pellets during the compounding process) or to the CE melt resin (e.g., during the extrusion process) can improve processing by reducing unwanted sticking of the CE melt resin to the die or mandrel (or to other components of the foam sheet production process). Such reduction in sticking may be achieved by the surface modifying additives inhibiting the fusing of cellulose esters caused by plasticizers. The addition of surface modifying additives may also reduce blocking of the cellulose ester foam sheets produced at the sheet forming section. Furthermore, surface modifying additives may also improve the foam sheet production process by allowing the process to be performed at lower temperatures.

Furthermore still, in some embodiments, the surface modifying additives may function as anti-static additives, which inhibit electrical sparks or arcing in the CE melt resin. The inhibition of electrical sparks or arcing can be particularly important when hydrocarbons are used as blowing agents, so as to reduce the chance of igniting the hydrocarbons and causing fires. Beneficially, surface modifying additives may also reduce the diffusion of blowing agents, such as hydrocarbons, out of the foam sheets or resulting articles. In some embodiments, hydrocarbons themselves may be used as surface modifying additives.

Nevertheless, more general examples of surface modifying additives that may be used with compounded CE material (e.g., during the compounding process) or to the CE melt resin (e.g., during the foam sheet production process) according to embodiments of the present invention include fatty acids, such as palmitic acid, tallow acid, stearic acid, oleic acid, linoleic and linolenic acids, arachidic/behenic acids, behenic acid, and erucic acid. Surface modifying additives may also include fatty acid amides, such as erucamides, oleoamides, stearmides, bhenamides, secondary amides, and bisamides.

Additional examples of surface modifying additives may include glycerol esters and/or stearate esters, such as monoglycerides, diglycerides, and triglycerides. The monoglycerides may include glycerol monostearate or monoglyceride derivatives, such as diacetyl tartaric acid esters of mono- and diglycerides (DATEM), ethoxylated monoglyceride, succinyl monoglyceride, and propylene glycol monoesters (PGME). Examples of surface modifying additives may also include metallic stearates such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate, and/or combinations thereof (e.g., Calcium/Zinc stearates) . Examples of surface modifying additives may also include waxes, such as polyolefin waxes (polypropylene wax and polyethylene wax), oxidized olefin waxes, ethylene acrylic acid (EAA) copolymer waxes, ethylene methyl acrylate (EMA) copolymer waxes, EAA ionomer axes, acrylic waxes, and/or natural waxes, such as rice bran wax, sunflower wax, sugar cane wax, candelilla wax, soy wax, bees wax, candelilla wax, and carnauba waxes.

Other, non-exclusive examples of surface modifying additives include aliphatic diesters (e.g., dioctyl adipate), polyglycol diesters, alkyl alkyether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkylether monoesters, and alkyl monoesters. In addition, various oils may be used as surface modifying additives, such as aromatic oils, napthenic oils, glyceride oils, silicon oils, and epoxidized oils (e.g., soybean oil and linseed oil). Thus, in some embodiments, the surface modifying additives comprise plasticizers, such as aliphatic diester plasticizers, polyester plasticizers, and the like. Furthermore, in some embodiments, surface modifying additives may comprise a polyhedral oligomeric silsesquioxane (POSS).

More generally, surface modifying additives used in embodiments of the present invention may have a lower polarity than the cellulose ester in compounded CE material (e.g., during the compounding process) or to the CE melt resin (e.g., during the foam sheet production process). For example, the surface modifying additives may have (based on Hansen solubility parameters): a total solubility parameter 5 of less than 25 MPa^1/2, less than 20 MPa^1/2, or less than 19.5 MPa^1/2; a dispersion force solubility parameter bd of less than 18 MPa^1/2, less than 16 MPa^1/2, or less than 14 MPa^1/2; a dipolar intermolecular force solubility parameter bd of less than 12 MPa^1/2, less than 8 MPa^1/2, or less than 4 MPa^1/2; and/or a hydrogen bond solubility parameter bh of less than 11 MPa^1/2, less than 10 MPa^1/2, or less than 9 MPa^1/2. However, in some other embodiments, the surface modifying additives used in embodiments of the present invention may have a higher polarity than the cellulose ester in compounded CE material (e.g., during the compounding process) or to the CE melt resin (e.g., during the foam sheet production process). For example, the surface modifying additives may have (based on Hansen solubility parameters): a total solubility parameter 5 of more than 21.5 MPa^1/2, more than 23 MPa^1/2, or more than 25 MPa^1/2. In addition, in some embodiments, surface modifying additives may have a boiling point greater than 200° C, greater than 220° C, greater than 240° C, greater than 260° C, greater than 280° C, or greater than 300° C. Furthermore, the surface modifying additives may have a molecular weight greater than 100 g/mol, greater than 150 g/mol, greater than 220 g/mol, greater than 260 g/mol, greater than 300 g/mol, or greater than 340 g/mol and/or no more than 1000 g/mol, no more than 2500 g/mol, or no more than 5000 g/mol. Furthermore still, it may be preferable for the surface modifying additives to not be soluble in the plasticizer(s) used in the cellulose ester compositions. For instance, it may be preferable for the surface modifying additives to not be soluble in triacetin. Finally, in some embodiments, the surface modifying additives may be biodegradable and/or food-compliant or FDA approved.

In one embodiment or in combination with any of the embodiments mentioned herein, the surface modifying additives are present at from 0.05 to 0.75 wt%, or 0.05 to 1 .0 wt%, or 0.05 to 2.5 wt%, or 0.05 to 5.0 wt%, or 0.75 to 1 .0 wt%, or 0.75 to 2.5 wt%, or 0.75 to 5.0 wt%, or 0.1 to 1 .0 wt%, or 0.1 to 2.5 wt%, 0.1 to 5.0 wt%, or 1 .0 to 2.5 wt%, or 1 .0 to 5.0 wt%, or 2.5 to 5.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the surface modifying additives used herein may comprise a combination or mixture of two or more different types of surface modifying additives.

Articles

Extruded sheets of cellulose ester foam may be formed using the extrusion section and/or the sheet forming section described above. Such extruded sheets comprise a structural material with a plurality of gaseous voids disposed throughout. Such gaseous voids are formed by expansion of the blowing agent in the form of a gas within the cellulose polymer melt. The structural material is cellulose ester based, with specific amounts of the compositional components of the structural material (e.g., cellulose ester, plasticizer, nucleating agents, surface modifying additives, etc.) having been described above in more detail. Articles may be formed from the extruded sheets of foam in accordance with embodiments, and may be particularly useful in the food service industry. Exemplary articles include meat trays. The articles may have one or more particularly advantageous properties. For example, the articles may be biodegradable and/or compostable, and/or the articles may have superior mechanical properties (e.g., strength, density, cell size, absorption, etc.).

Such cellulose ester foamed articles may be formed from cellulose ester foamed sheets by thermoforming, in which heat and optionally pressure are applied to the foamed sheet within a mold to create a three-dimensional article that retains its shape after release from the mold. For example, in some embodiments, the foamed sheets will be heated to a surface temperature from 40-100° C, from 50-80 °C, or from 50-70 °C greater than the Tg of the foamed sheet. In some embodiments, the Tg of the foamed sheet will be about 120 °C. As such, the thermoforming process may heat the foamed sheet to a surface temperature from 150-210° C or from 160-200° C.

In more detail, embodiments of the present invention may include a foamed tray, as illustrated in FIG. 6, which may be configured as a food tray to support one or more food items such as meat. The foamed tray may be formed with from 50 to 99 wt. % cellulose ester. To increase the stiffness of the cellulose ester based foamed tray, the tray may comprise at least one elongated reinforcing member. The at least one reinforcing member may include a primary reinforcing member “P,” as illustrated in FIG. 6, which extends laterally across at least 20% of a width of the tray. The primary reinforcing member P may be positioned no more than 0.25 inches apart from a lateral centerline “Y” of the tray. In other embodiments, the primary reinforcing member P may be positioned no more than 0.20, no more than 0.15, no more than 0.10, and/or no more than 0.05 inches apart from the lateral centerline Y of the tray. In still other embodiments, the primary reinforcing member P may be generally aligned with the lateral centerline Y of the tray.

Foamed trays formed according to embodiments of the present invention may be formed in various sizes. For example, as illustrated in FIG. 7, the tray may have a width “W” in the range of 2-12 inches, 3-10 inches, or 5-9 inches and a length “L” from 4-24 inches, 5-18 inches, or 6-15 inches. Thus, in some embodiments, the tray may have a length that is 1 .2-4 times, 1 .4-3 times, or 1 .5-2 times the width of the tray.

As illustrated in FIGS. 6 and 7, the foamed tray may include a base that is substantially planar, as well as a rim that is raised above the base and extends around the periphery of the foamed tray. In some embodiments, the substantially planar portion of the base makes up 40-95%, 50-90%, or 60-85 percent of the total area of the base. The top surface of the base and the surrounding rim define a receiving area (e.g., a bowl) within which items (e.g., meat, cheese, vegetables, fruits, or other foodstuff) may be held and supported. In some embodiments, the receiving area may be divided up into one or more different sections or compartments (e.g., via the reinforcing members or other surface contours), such that an individual piece (or pieces) of foodstuff may be supported within each of the compartments. Regardless, an area of the base may be from 5-100 square inches, 10-75 square inches, or 20-50 square inches. A rim heigh height (measured from a bottom surface of the tray to a top surface of the rim) may be from 0.2-4 inches, 0.4-2 inches, or 0.5-1 inch, and a rim width (i.e., a lateral or longitudinal distance “Rw” measured from a side or an end of the tray to the point at which the rim meets the base, as illustrated in FIG. 7) may be from 0.06-0.75 inches, 0.10-0.50 inches, or 0.25-0.50 inches. Alternatively, the rim width “Rw” may be from about 0.01 W to 0.1 W or from about 0.03W to 0.06W, where “W” is the width of the tray as previously described. A ratio of the base area to the rim area may be from 1-10, 1 .5-6, or 2-4. In addition, the tray may have a depth (measured from a top surface of the rim to the top surface of the base) from 0.3 to 4 inches, from 0.5 to 3 inches, from 1 to 3 inches, from 1 to 2 inches, from 1 .25 to 2 inches, about 1 .25 inches, or about 1 .5 inches. Furthermore, the tray may have a thickness (i.e., the thickness of the cellulose ester foam material) from 1 to 10 mm, from 1 to 8 mm, from 2 to 8 mm, from 3 to 7 mm, from 4 to 6 mm, about 4 mm, about 5 mm, or about 6 mm, and/or less than 5 mm, less than 4 mm, less than 3 mm, or less than 2 mm. Alternatively, or in addition, the tray or other article may have a thickness (i.e., the thickness of the cellulose ester foam material) from 100-400 mils, 120-300 mils, 150-250 mils.

Turning to the reinforcing members, as noted above, the foamed tray will be formed to include at least one laterally extending reinforcing member P that is positioned no more than 0.25 inches apart (in a longitudinal direction) from a lateral centerline Y of the tray. However, additional embodiments may provide for the tray to include more than one reinforcing member. For example, the tray may comprise at least three reinforcing members including the primary reinforcing member P, a first supplemental reinforcing member “S1 ,” and a second supplemental reinforcing member “S2,” each of which are illustrated in FIG. 6. As shown, the first and second supplemental reinforcing members S1 , S2, are positioned on opposite sides, in a longitudinal direction, of the primary reinforcing member P. As such, the reinforcing members P, S1 , and S2 extend substantially parallel to one another. As will be described in more detail below, the trays may include other numbers of reinforcing members, such as five, seven, or more.

The reinforcing members may comprise raised ribs or other structures that extend from an exterior surface of the base of the tray. For example, the reinforcing members may extend above a top surface of the base of the tray and/or below a bottom surface of the base of the tray. The reinforcing members may extend above or below the surface of the base of the tray from 2 to 10 mm, from 3 to 8 mm, or from 4 to 7 mm. Nevertheless, in some embodiments, the reinforcing members will be integrally formed with the remaining portions of the tray.

The reinforcing members may, in some embodiments, be separated from each from 16 to 64 mm, from 24 to 38 mm, or about 32 mm. Alternatively, given that the foamed tray may have a length L, the reinforcing members may be separated from each from 0.02L to 0.20L, from 0.5L to 0.15L, or about 0.10L. Although the reinforcing members described above (and illustrated in FIG. 6) are shown as extending in a lateral direction, it should be understood that the tray may include one or more elongated reinforcing members that extend in other directions, such as longitudinally, diagonally, circularly, or the like. The laterally-extending reinforcing members may, in some embodiments, extend across at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 75% of the width of the tray and/or not more than 100%, 95%, 90%, 80%, 70%, 60%, or 50% of the width of the tray. In other embodiments the reinforcing members may extend across 50-100%, 60-95%, or 70-90% of the width of the tray. Thus, in some embodiments, the reinforcing members may extend across the width of the tray (e.g., along the base) without contacting the rim. However, in some other embodiments, the reinforcing members may contact or form part of the rim so as to interconnect the base and the rim.

In some embodiments, the reinforcing members may be formed within at least a portion of the rim of the tray, such that that the rim includes part of the reinforcing member. As a result, the reinforcing members may extend nearly entirely (or entirely) across the width of the tray. In some embodiment, the reinforcing members may be formed using molding protuberances positioned within (or that form part of) the thermoforming molds used to thermoform the foam sheets into the foam trays. Specifically, the molding protuberances may comprise elongated and/or arcuate projection elements positioned within a bottom portion of the molds. As such, the projection elements extend upward and/or inward from a molding surface of the thermoforming molds. Upon a foam sheet being positioned within the thermoforming mold, the molding protuberances will force the foam of the foam sheet upward and/or inward at the position of the molding protuberance. As a result, the reinforcing members will be formed from the foam material of the base and/or rim portions of the tray. In such embodiments, the reinforcing members may be formed (due to the molding protuberances) as elongated indentations that extend upward from a bottom surface of the base of the tray. Similarly, the reinforcing members may be formed (due to the molding protuberances) as elongated indentations that extend inward from an outside surface of the rim of the tray. Correspondingly, the reinforcing members may be formed (due to the molding protuberances) as elongated projections that extend upward from a top surface of the base of the tray. Similarly, the reinforcing members may be formed (due to the molding protuberances) as elongated projections that extend inward from an interior surface of the rim of the tray.

As noted previously, the reinforcing members may extend generally entirely across the width of the tray. In addition, the reinforcing members may have a thickness (e.g., measured from a top surface of the base of the tray to a top surface of the reinforcing member) from 1/16 to 1/2 inch, from 1/8 to 1/4 inch, or about 1/8 inch, or about 1/4 inch. Furthermore, the reinforcing members may have a width (e.g., measured in a longitudinal direction in FIG. 6) from 1/16 to 1/2 inch, from 1/8 to 1/4 inch, or about 1/8 inch, or about 1/4 inch. The sizes of the reinforcing members (e.g., the thicknesses and/or widths) may be dependent on the sizes of the molding protuberances used during thermoforming.

Although FIG. 6 illustrate the foam tray as having three elongated reinforcing members, embodiments provide for the foam trays of the present invention to include various numbers of reinforcing members. For example, FIG. 8 illustrates an embodiment of a tray with five reinforcing members. Trays with other numbers are contemplated, such as a tray with one reinforcing member that extends generally along the lateral centerline of the tray. In addition, trays with seven reinforcing members, nine reinforcing members, or more are also contemplated. Regardless of the number of reinforcing members included in the tray, some embodiments provide for at least one reinforcing member (e.g., a primary reinforcing member) to extend generally along (or within 0.25 inches of) the lateral centerline of the tray. The remaining reinforcing members (e.g., secondary reinforcing members) may be positioned on either side of the primary reinforcing members (e.g., spaced apart in a longitudinal direction of the tray of FIG. 8).

Other foamed trays with reinforcing members are also contemplated. For example, FIG. 9 illustrates a foam tray with circular-shaped reinforcing members. In particular, the tray of FIG. 9 includes a primary reinforcing member that extends generally along the lateral centerline of the tray. In some embodiments, the primary reinforcing member may extend along the entire width of the tray, such that the primary reinforcing member extends at least partially through the rim of the tray. In other embodiments, the primary reinforcing member may only extend along the base of the tray. Regardless, the tray may also include a pair of diagonal reinforcing members that extend generally diagonally across the tray from opposing corners of the tray. In some embodiments, the diagonal reinforcing member may extend along the entire diagonal distance of the tray, such that the diagonal reinforcing members extend at least partially through the rim of the tray. In other embodiments, the diagonal reinforcing member may only extend along the diagonal length of the base of the tray.

The tray also includes a plurality of circular-shaped, concentric reinforcing members. Such circular-shaped reinforcing members may include an inner circular-shaped reinforcing member with a center coinciding with a center of the base of the tray. The diameter of the inner circular-shaped reinforcing member may have a length of from 10-40% of the width of the tray, from 20-30% of the width of the tray, at least 20% of the width of the tray, or about 25% the width of the tray. The circular-shaped reinforcing members may also include a central circular-shaped reinforcing member with a center coinciding with a center of the base of the tray. The central circular-shaped reinforcing member may have a diameter that is approximately equal to the width of the base of the tray. As such, the central circular-shaped reinforcing member is positioned around the inner circular-shaped reinforcing member. Finally, the circular-shaped reinforcing members may also include an outer circular-shaped reinforcing member with a center coinciding with a center of the base of the tray. The outer circular-shaped reinforcing member may have a diameter that is greater than the width of the base of the tray, such that only arcuate portions of the outer circular-shaped reinforcing member are present on the tray. Nevertheless, the outer circular-shaped reinforcing member is positioned around the central and inner circular-shaped reinforcing members.

FIG. 10 illustrates another embodiment of a foam tray with reinforcing members. Such reinforcing members extend inward from the rim of the tray, and may, thus, be referred to as edge reinforcing members. In more detail, the tray includes a pair of reinforcing members that extend inward, towards each other from opposite sides of the rim, in a lateral direction towards the center of the base of the tray. The laterally-extending reinforcing members may extend generally along the lateral centerline of the tray. However, the laterally-extending reinforcing members do not extend entirely across the width of the base of the tray, such that there is an open area (i.e., an area without reinforcing members) within the center portion of the base of the tray. In some embodiments, the laterally-extending reinforcing members may each extend from 10-40% of the width of the tray, from 20-30% of the width of the tray, at least 20% of the width of the tray, or about 25% the width of the tray. In some embodiments, the laterally-extending reinforcing members may extend only along the base of the tray, or may, alternatively, extend along the base and the rim of the tray. The tray of FIG. 10 may also include a pair of reinforcing members that extend inward, towards each other from opposite ends of the rim, in a longitudinal direction towards the center of the base of the tray. The longitudinally-extending reinforcing members may extend generally along the longitudinal centerline of the tray. However, the longitudinally-extending reinforcing members do not extend entirely across the length of the base of the tray, such that there is an open area (i.e., an area without reinforcing members) within the center portion of the base of the tray. In some embodiments, the longitudinally-extending reinforcing members may each have a length from 10-40% of the width of the tray, from 20-30% of the width of the tray, at least 20% of the width of the tray, or about 25% the width of the tray. In some embodiments, the longitudinally-extending reinforcing members may extend only along the base of the tray, or may, alternatively, extend along the base and the rim of the tray.

FIG. 1 1 illustrates an additional embodiment of a tray with edge reinforcing members, such that the tray of FIG. 11 is similar to the tray shown in FIG. 10. However, the tray of FIG. 11 includes additional laterally-extending reinforcing members that extend from the sides of the tray. Specifically, each side of the tray may include two additional laterally-extending reinforcing members that extend on opposite sides (in a longitudinal direction) of a respective centrally-positioned (i.e., in alignment with the lateral centerline of the tray) laterally-extending reinforcing member. Each of the two additional laterally-extending reinforcing members positioned on a given side of the tray may be positioned no more than 1/2 inch, no more than 1/4 inch, or no more than 1/8 inch from a respective centrally-positioned laterally-extending reinforcing member. The remaining characteristics of the laterally-extending reinforcing members (e.g., lengths) may be the same as those corresponding characteristics of the laterally-extending reinforcing members from FIG. 10. In addition, each end of the tray of FIG. 11 may include a pair of longitudinally- extending reinforcing members. Such longitudinally-extending reinforcing members may not coincide with the longitudinal centerline of the tray, but may be a least partially offset from the longitudinal centerline. For example, the longitudinally-extending reinforcing members may be offset from the longitudinal centerline by no more than 1/2 inch, no more than 1/4 inch, or no more than 1/8 inch. In addition, each of the additional longitudinally-extending reinforcing members on a given end of the tray may be positioned no more than 1/2 inch, no more than 1/4 inch, or no more than 1/8 inch apart from each other. The remaining characteristics of the longitudinally-extending reinforcing members (e.g., lengths) may be the same as those corresponding characteristics of the longitudinally-extending reinforcing members from FIG. 10.

Finally, FIG. 12 illustrates a foam tray with additional configurations of reinforcing members. The tray of FIG. 12 may include a pair of longitudinally- extending reinforcing members that are generally the same as those longitudinally-extending reinforcing members described for the tray of FIG. 10. The tray of FIG. 12 may also include four diagonally-extending reinforcing members that each extend inward from one of the corners of the tray in a diagonal direction towards the center of the base of the tray. Such diagonally- extending reinforcing member may be referred to as corner reinforcing members. The diagonally-extending reinforcing members do not extend entirely across the base of the tray, such that there is an open area (i.e., an area without reinforcing members) within the center portion of the base of the tray. In some embodiments, the diagonally-extending reinforcing members may each have a length from 10-40% of the width of the tray, from 20-30% of the width of the tray, at least 20% of the width of the tray, or about 25% the width of the tray. In some embodiments, the diagonally-extending reinforcing members may extend only along the base of the tray, or may, alternatively, extend along the base and the rim of the tray. Furthermore, each side of the tray of FIG. 12 may include a pair of laterally-extending reinforcing members. Such laterally-extending reinforcing members may not coincide with the lateral centerline of the tray, but may be a least partially offset from the lateral centerline. For example, the laterally-extending reinforcing members may be offset from the lateral centerline by no more than 1/2 inch, no more than 1/4 inch, or no more than 1/8 inch. In addition, each of the laterally-extending reinforcing members on a given end of the tray may be positioned no more than 1/2 inch, no more than 1/4 inch, or no more than 1/8 inch apart from each other. The remaining characteristics of the laterally-extending reinforcing members (e.g., lengths) may be the same as those corresponding characteristics of the laterally-extending reinforcing members from FIG. 10.

Embodiments provide for the above described foamed tray to be formed according to the processes described herein. In particular, a mixed composition comprising cellulose ester (e.g., present in an amount from about 50 wt. % to about 99 wt. %) can be extruded through an extruder to form a cellulose ester foamed sheet. The foamed sheet can then be thermoformed to form the tray, which can include a base, a rim, and at least one reinforcing member. As such, each of the base, the rim, and the reinforcing members may all be formed from a single sheet of cellulose ester foam. The resulting foamed tray can be used to support food products, such as meat. Thus, in some embodiments, an absorbent pad will be placed on the top of the base, within the receiving area, such that liquid from the meat (or other foodstuff) can be absorbed by the pad. In addition, shrink film can be wrapped around the tray so as to securely hold the meat therein and to protect the meat from the environment. Beneficially, the reinforcing members provide additional stiffness to the tray, such that the tray will not overly flex or fail under the forces applied by the shrink film. For example, the reinforcing members may provide additional stiffness and support against the shrink film, which exerts a force on at least two sides and/or on at least four sides of the tray. Such a force from the shrink film may be a compressive force at least 0.1 MPa, 0.5 MPa, or 4 MPa. In other embodiments, the foamed trays may be configured to be wrapped with an overwrap film that covers and protects the tray and the foodstuff therein without imparting significant pressures and/or forces onto the trays.

In one embodiment or in combination with any of the embodiments mentioned herein, the foamed articles, e.g., trays, may have a density less than .20 g/cm³, less than 0.18 g/cm³, less than 0.15 g/cm³, less than 0.12 g/cm³, less than less than 0.10 g/cm³, less than 0.08 g/cm³, less than less than 0.06 g/cm³, or less than less than 0.04 g/cm³, or from 0.04 to 0.8 g/cm³, 0.04 to 0.6 g/cm³, 0.04 to 0.5 g/cm³, 0.04 to 0.4 g/cm³, 0.04 to 0.3 g/cm³, 0.04 to 0.2 g/cm³, 0.04 to 0.15 g/cm³, 0.04 to 0.12 g/cm³, 0.04 to 0.10 g/cm³, 0.04 to 0.08 g/cm³, 0.04 to 0.06 g/cm³, 0.06 to 0.8 g/cm³, 0.06 to 0.6 g/cm³, 0.06 to 0.5 g/cm³, 0.06 to 0.4 g/cm³, 0.06 to 0.3 g/cm³, 0.06 to 0.2 g/cm³, 0.06 to 0.15 g/cm³, 0.06 to 0.12 g/cm³, 0.06 to 0.10 g/cm³, 0.06 to 0.08 g/cm³, 0.08 to 0.8 g/cm³, 0.08 to 0.6 g/cm³, 0.08 to 0.5 g/cm³, 0.08 to 0.4 g/cm³, 0.08 to 0.3 g/cm³, 0.08 to 0.2 g/cm³, 0.08 to 0.15 g/cm³, 0.08 to 0.12 g/cm³, 0.08 to 0.10 g/cm³, 0.1 to 0.8 g/cm³, 0.1 to 0.6 g/cm³, 0.1 to 0.5 g/cm³, 0.1 to 0.4 g/cm³, 0.1 to 0.3 g/cm³, 0.1 to 0.2 g/cm³, 0.1 to 0.15 g/cm³, 0.1 to 0.12 g/cm³, 0.2 to 0.8 g/cm³, 0.2 to 0.6 g/cm³, 0.2 to 0.5 g/cm³, 0.2 to 0.4 g/cm³, 0.2 to 0.3 g/cm³, 0.3 to 0.6 g/cm³, 0.3 to 0.5 g/cm³, 0.3 to 0.4 g/cm³, 0.4 to 0.6 g/cm³, 0.4 to 0.5 g/cm³, or 0.5 to 0.6 g/cm³.

In one embodiment or in combination with any of the embodiments mentioned herein, the average foam cell size is from 40 gm to 600 gm, or 50 gm to 600 gm, or 60 gm to 600 gm, or 70 gm to 600 gm, or 80 gm to 600 gm, or 90 gm to 600 gm, or 100 gm to 600 gm, or 150 gm to 600 gm, or 200 gm to 600 gm, or 250 gm to 600 gm, or 300 gm to 600 gm, or 400 gm to 600 gm, or 500 gm to 600 gm, or 40 gm to 550 gm, or 40 gm to 500 gm, or 40 gm to 450 gm, or 40 gm to 400 gm, or 40 gm to 350 gm, or 40 gm to 300 gm, or 40 gm to 250 gm, or 40 gm to 200 gm, or 40 gm to 150 gm, or 40 gm to 100 gm.

Furthermore, it should be understood that because the foamed articles, e.g., trays, are formed from the cellulose ester described herein, the foamed articles may include any of the components and/or additives, as well as any resulting properties, of the cellulose ester based materials described herein.

Examples

The below examples illustrate how foam trays formed according to embodiments of the present invention can include beneficial mechanical properties, such as improved strength characteristics. Each of the below examples was obtained by carrying out a Tray Stiffness Test using a force tester that included a Ryback & Ryback motorized test stand with a Mark-10 Series 5 Model M5-50 force gauge communicatively coupled with MeasurGauge Plus software. During the Tray Stiffness Tests, the trays were compressed in the lateral direction to measure a “side edge-to-edge stiffness” of the trays. Such side edge-to-edge stiffness is a beneficial characteristic to gauge the ability of a tray to resist deformation during plastic film overwrapping after food has been placed into the tray.

The Tray Stiffness Test was performed as follows: each of the tested trays was oriented in a landscape direction with one lateral side of the tray configured as a bottom side positioned within an elongated rail guide secured to a bottom of the test stand. The opposite lateral side was configured as a top side that was open for engagement with an elongated contact element secured to an actuating ram of the test stand. The contact element had a length approximately 3/4 the length of the top side of the tray and having a center that was generally aligned with the lateral centerline of the tray. The actuating ram of the test stand was then moved vertically downward, applying a force to the lateral sides of the tray.

Stiffness of a tray is based on Hooke’s law (i.e., F=kAL), where an amount of deformation (AL) of the tray is produced by a force (F). A proportionality constant (k) depends on the shape and composition of the tray and the direction of the force. Thus, Hooke’s law provides for the slope of the linear portion of the curve F=kAL, which is the proportionality constant k, to be expressed as stiffness. As such, the stiffness (k) of a tray could be measured by the MeasurGauge Plus software using the force value (F) obtained by the force gauge as the test stand moved vertically downward to produce an amount of deformation (AL) of the tray.

To obtain the stiffness values according to the Tray Stiffness Test, the contact element of the test stand was initially moved downward by the ram 0.5 inches before initial contact with the top side of the tray. After such initial movement of 0.25 inches, the MeasurGauge Plus software was zeroed out. Thereafter, the contact element of the test stand was moved vertically downward, via the ram, at a speed of 0.8333 mm/sec for a total test time of 30 seconds. The MeasurGauge Plus software began making data reads upon contact with the top side of the tray. The MeasurGauge Plus software performed 50 data reads of force (F) and deformation (AL) during the test, such that an interval distance between data reads was 0.0167 mm and an interval time between data reads was 0.0240 sec. The total distance traveled by the test stand was 25 mm, and the total number of data reads was 1500.

Example A

Seven foamed trays were thermoformed from a foamed sheet using a Hydrotrim Lab thermoformer. The thermoformer comprised a mold with top and bottom heating platens in an oven. A timer was used to set the hold time in the oven. A vacuum was used for drawing the material in the molds and plug assist for use with complicated parts. The trays evaluated for this study were made using vacuum only and the top and bottom platens were heated to 260°C. The foam sheet was heated for 35 seconds to generate a sheet temperature between 182 to 188°C.

The foamed sheet comprised cellulose acetate (Ds 2.5) with 20% Triacetin as a plasticizer and less than 2% stabilizers and colorants. The foamed sheet was formed with 1% Foamazol 73S chemical blowing agent and 1% ABT 1000 talc as a nucleator. The foamed sheet was made with 2.6% Pentane as a primary blowing agent. The primary extruder had a melt temperature of 210°C and the secondary extruder had a melt temperature of 187°C. The foamed sheet was made at a die pressure of 33 bar. The foamed sheet had a density of 0.095g/cc, a sheet thickness of 4mm, and average cell size of 340 microns.

The foamed tray density decreased to 0.072 g/cc upon thermoforming. The resulting foamed trays each had a length of 8.6 inches, a width of 6.5 inches, and a height (measured from a bottom surface of the base of the tray to a top surface of a rim of the tray) of 1 .25 inches.

As illustrated below in Table 1 , the seven foamed trays were formed in the manner discussed above and tested using the Tray Stiffness Test. The first tray EX-1 was a control tray formed without any reinforcing members, thus, configured similar to the tray illustrated in FIG. 7. The second and fifth trays EX-2 and EX-5 were each formed with a single reinforcing member that extended along the lateral centerline of the tray across the entire base of the tray, with the reinforcing member also forming part of the lip of the tray. The third and sixth trays EX-3 and EX-6 were each formed with three reinforcing members. Specifically, the third and sixth trays EX-3 and EX-6 were configured similar to the tray shown in FIG. 6. The fourth and seventh trays EX-4 and EX-7 were each formed with five reinforcing members. Specifically, the fourth and seventh trays EX-4 and EX-7 were configured similar to the tray shown in FIG. 8. The heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the second tray EX-2, the third tray EX-3, and the fourth tray EX- 4 were approximately 1/4 inch, which was relatively larger than the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the fifth tray EX-5, the sixth tray EX-6, and the seventh tray EX-7 that were approximately 1/8 inch.

Tablel

As illustrated in Table 1 it was found that the third tray EX-3 and the fourth tray EX-4, which were formed with three and five reinforcing members, respectively, showed improved stiffness versus the control tray EX-1 . All other trays shown no improvement, instead having a lower stiffness than the control tray EX-1 . It was noted that the reinforcing members of the third tray EX-3 and the fourth tray EX-4 had relatively larger heights (i.e., 1/4 inch) than the heights (i.e., 1/8 inch) of the reinforcing members of any of the remaining trays EX-5, EX-6, and EX-7.

Example B

Three foamed trays were thermoformed from a foamed sheet using a Hydrotrim Lab thermoformer. The thermoformer comprised a mold with top and bottom heating platens in an oven. A timer was used to set the hold time in the oven. A vacuum was used for drawing the material in the molds and plug assist for use with complicated parts. The trays evaluated for this study were made using vacuum only and the top and bottom platens were heated to 260°C. The foam sheet was heated for 35 seconds to generate a sheet temperature between 182 to 188°C. The foamed sheet comprised cellulose acetate (Ds 2.5) with 20% Triacetin as a plasticizer and less than 2% stabilizers and colorants. The foamed sheet was formed with 1% Foamazol 73S chemical blowing agent and 1% ABT 1000 talc as a nucleator. The foamed sheet was made with 2.5% Pentane as a primary blowing agent. The primary extruder had a melt temperature of 210°C and the secondary extruder had a melt temperature of 187°C. The foamed sheet was made at a die pressure of 40 bar. The foamed sheet had a density of 0.109g/cc, a sheet thickness of 5 mm, and average cell size of 702 microns.

The resulting foamed trays each had a length of 8.6 inches, a width of 6.5 inches, and a height (measured from a bottom surface of the base of the tray to a top surface of a rim of the tray) of 1 .25 inches. As illustrated below in Table 2, the three foamed trays were formed in the manner discussed above and tested using the Tray Stiffness Test.

The first tray EX-8 was a control tray formed without any reinforcing members, thus, configured similar to the tray illustrated in FIG. 7. The second tray EX-9 was configured similar to the tray shown in FIG. 9 with multiple reinforcing members, including a laterally extending reinforcing member, diagonally-extending reinforcing members, and circularly-shaped reinforcing members. The third tray EX-10 was formed with multiple laterally-extending and longitudinally-extending reinforcing members (i.e., ten total edge reinforcing members). Specifically, the third tray EX-10 was configured similar to the tray shown in FIG. 11 .

Table 2

As illustrated in Table 2 it was found that both of the trays second tray EX-9 and the third tray EX-10 showed significantly improved stiffness values versus the control tray EX-8. Specifically, the second tray EX-9 with the circular-shaped reinforcing members showed a stiffness increase of 35%, while the third tray EX-10 with the multiple edge reinforcing members showed a stiffness increase of 45%.

Example C

Four foamed trays were thermoformed from a foamed sheet using a Hydrotrim Lab thermoformer. The thermoformer comprises a mold with top and bottom heating platens in an oven. A timer was used to set the hold time in the oven. A vacuum was used for drawing the material in the molds and plug assist for use with complicated parts. The trays evaluated for this study were made using vacuum only and the top and bottom platens were heated to 260°C. The foam sheet was heated for 35 seconds to generate a sheet temperature between 190 to 196°C.

The foamed sheet comprised cellulose acetate (Ds 2.5) with 20% Triacetin as a plasticizer and less than 2% stabilizers and colorants. The foamed sheet was formed with 1% Foamazol 73S chemical blowing agent and 1% ABT 1000 talc as a nucleator. The foamed sheet was made with 2.3% Pentane as a primary blowing agent. The primary extruder had a melt temperature of 210°C and the secondary extruder had a melt temperature of 187°C.

The resulting foamed trays each had a length of 8.6 inches, a width of 6.5 inches, and a height (measured from a bottom surface of the base of the tray to a top surface of a rim of the tray) of 1 .25 inches. As illustrated below in Table 3, the four foamed trays were formed in the manner discussed above and tested using the Tray Stiffness Test.

The first and third trays EX-1 1 and EX-13 were control trays formed without any reinforcing members, thus, configured similar to the tray illustrated in FIG. 7. The second and fourth trays EX-12 and EX-14 were formed with multiple laterally-extending and longitudinally-extending reinforcing members (i.e., ten total edge reinforcing members). Specifically, the second and fourth trays EX-12 and EX-14 were configured similar to the tray shown in FIG. 11 . Notably, the first and second trays EX-11 and EX-12 were formed from foam with average cell sizes of 295 microns and a foam density of 0.108 g/cc. Such a cell size was achieved by forming the associated foam sheet using a die pressure of 32 bar. In contrast, the third and fourth trays EX-13 and EX-14 were formed from a foam sheet with an average cell size of 148 microns and a foam density of 0.103 g/cc. Such a cell size was achieved by forming the associated foam sheet using a die pressure of 70 bar.

Table 3

As illustrated by Table 3 above, each of the trays formed with reinforcing members showed a significant increase in stiffness versus the control trays. Specifically, the second tray EX-12 showed an 89% increase in stiffness versus the control tray EX-11 . Similarly, the fourth tray EX-14 showed a 99% increase in stiffness versus the control tray EX-13. Furthermore, the trays formed with a smaller cell size showed an increase in stiffness versus the corresponding trays formed with a larger cell size. Specifically, the third tray EX-13, which was a control tray, showed a 9% increase in stiffness versus the first tray EX-11 , which was also a control tray. Similarly, the fourth tray EX-14, which was formed with reinforcing members, showed a 15% increase in stiffness versus the second tray EX-12, which was similarly formed with reinforcing members. Example D

Eight foamed trays were thermoformed from a foamed sheet using a Hydrotrim Lab thermoformer. The thermoformer comprised a mold with top and bottom heating platens in an oven. A timer was used to set the hold time in the oven. A vacuum was used for drawing the material in the molds and plug assist for use with complicated parts. The trays evaluated for this study were made using vacuum only and the top and bottom platens were heated to 260°C. The foam sheet was heated for 35 seconds to generate a sheet temperature between 182 to 188°C.

The foamed sheet comprised cellulose acetate (Ds 2.5) with 15% or 20% Triacetin as a plasticizer (see Table 4 below) and less than 2% stabilizers and colorants. The foamed sheet was formed with 1% Foamazol 73S chemical blowing agent and 1% ABT 1000 talc as a nucleator. The foamed sheet was made with 2.5% Pentane as a primary blowing agent. The primary extruder had a melt temperature of 210° to 220°C and the secondary extruder had a melt temperature of 180° to 200°C. The foamed sheet was made at a die pressure of 30 to 50 bar.

The resulting foamed trays each had a length of 8.6 inches, a width of 6.5 inches, and a height (measured from a bottom surface of the base of the tray to a top surface of a rim of the tray) of 1 .25 inches. As illustrated below in Table 4, the eight foam trays were formed in the manner discussed above and tested using the Tray Stiffness Test. It is noted that the first five trays (i.e., EX- 15 to EX-19) had a thickness of 5 mm and included 20% plasticizer, whereas the last three trays (i.e., EX-20 to EX-22) had a thickness of 4 mm and included 15% plasticizer.

The first tray EX-15 was a control tray formed without any reinforcing members, thus, configured similar to the tray illustrated in FIG. 7. The second tray EX-16 was configured with multiple laterally-extending and longitudinally- extending reinforcing members (i.e., four total edge reinforcing members). Specifically, the second tray EX-16 was configured similar to the tray shown in FIG. 10. The third tray EX-17 was also configured with multiple laterally- extending and longitudinally-extending reinforcing members (i.e., four total edge reinforcing members). Specifically, the third tray EX-17 was also configured similar to the tray shown in FIG. 10. Contrastingly, the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the second tray EX-16 was approximately 1/4 inch, which was relatively larger than the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the third tray EX-17 that was approximately 1/8 inch.

The fourth tray EX-18 was configured with multiple laterally-extending, longitudinally-extending, and diagonally-extending reinforcing members (i.e., ten total edge and corner reinforcing members). Specifically, the fourth tray EX-18 was configured similar to the tray shown in FIG. 12. The fifth tray EX- 19 was also configured with multiple laterally-extending, longitudinally- extending, and diagonally-extending reinforcing members (i.e., ten total edge and corner reinforcing members). Specifically, the fifth tray EX-19 was also configured similar to the tray shown in FIG. 12. Contrastingly, the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the fourth tray EX-18 was approximately 1/4 inch, which was relatively larger than the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the fifth tray EX-19 that was approximately 1/8 inch.

The sixth tray EX-20 was a control tray formed without any reinforcing members, thus, configured similar to the tray illustrated in FIG. 7. The seventh tray EX-21 was configured with multiple laterally-extending, longitudinally- extending, and diagonally-extending reinforcing members (i.e., ten total edge and corner reinforcing members). Specifically, the seventh tray EX-21 was configured similar to the tray shown in FIG. 12. The eighth tray EX-22 was also configured with multiple laterally-extending, longitudinally-extending, and diagonally-extending reinforcing members (i.e., ten total edge and corner reinforcing members). Specifically, the eighth tray EX-22 was also configured similar to the tray shown in FIG. 12. Contrastingly, the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the eighth tray EX-22 was approximately 1/4 inch, which was relatively larger than the heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for the seventh tray EX-21 that were approximately 1/8 inch.

Table 4

As illustrated above, each of the trays formed with reinforcing members had improved stiffnesses over the control trays. Specifically, the second tray EX-16 showed a 17% improvement in stiffness versus the control tray EX-15. The third tray EX-17 showed a 20% improvement in stiffness versus the control tray EX-15. The fourth tray EX-18 showed a 30% improvement in stiffness versus the control tray EX-15. The fifth tray EX-19 showed a 13% improvement in stiffness versus the control tray EX-15. Similarly, the seventh tray EX-21 showed a 22% improvement in stiffness versus the control tray EX-20. And the eighth tray EX-22 showed a 30% improvement in stiffness versus the control tray EX-20.

In addition to the improved stiffness values found in the trays with reinforcing members, it was found that reduced plasticizer content also increased the stiffness. Specifically, the control tray EX-20 had a higher stiffness than the control tray EX-15, even though the control tray EX-20 was formed with a lower thickness. Similarly, the seventh tray EX-21 had a higher stiffness than the third tray EX-17, and the eighth tray EX-22 had a higher stiffness than the second tray EX-16.

Example E

Three foamed trays were thermoformed from a foamed sheet using a Hydrotrim Lab thermoformer. The thermoformer comprises a mold with top and bottom heating platens in an oven. A timer was used to set the hold time in the oven. A vacuum was used for drawing the material in the molds and plug assist for use with complicated parts. The trays evaluated for this study were made using vacuum only and the top and bottom platens were heated to 260°C. The foam sheet was heated for 35 seconds to generate a sheet temperature between 182 to 188°C.

The foamed sheet comprised cellulose acetate (Ds 2.5) with 20% Triacetin as a plasticizer and less than 2% stabilizers and colorants. The foamed sheet was formed with 1% Foamazol 73S chemical blowing agent and 1% ABT 1000 talc as a nucleator. The foamed sheet was made with 2.5% Pentane as a primary blowing agent. The primary extruder had a melt temperature of 210°, and the secondary extruder had a melt temperature of 187°C. The foam sheet was made at a pressure of 40 bar. The foam sheet had a density of 0.109g/cc, a sheet thickness of 5 mm, and an average cell size of 702 microns.

The resulting foamed trays had a length of 14 inches, a width of 8.6 inches, and a height (measured from a bottom surface of the base of the tray to a top surface of a rim of the tray) of 1 .6 inches. As illustrated below in Table 5, the three foamed trays were formed in the manner discussed above and tested using the Tray Stiffness Test.

The first tray EX-23 was a control tray formed without any reinforcing members, thus, configured similar to the tray illustrated in FIG. 7. The second tray EX-24 was configured with multiple laterally-extending and longitudinally- extending reinforcing members (i.e., ten total edge reinforcing members). Specifically, the second tray EX-24 was configured with reinforcing members similar to the tray shown in FIG. 11 . The third tray EX-25 was configured with multiple laterally-extending, longitudinally-extending, and diagonally-extending reinforcing members (i.e., ten total edge and corner reinforcing members). Specifically, the third tray EX-24 was configured similar to the tray shown in FIG. 12. The heights of the reinforcing members (measured from a top surface of the base of the tray to the top surface of the reinforcing member) for each of the second and third trays EX-24 and EX-25 was approximately 1/4 inch.

Table 5

As illustrated above, each of the trays formed with reinforcing members showed improved stiffnesses over the control tray. Specifically, the second tray EX-24 showed a 40% improvement in stiffness versus the control tray EX-23. And the third tray EX-25 showed a 33% improvement in stiffness versus the control tray EX-23.

DEFINITIONS

It should be understood that the following is not intended to be an exclusive list of defined terms. Other definitions may be provided in the foregoing description, such as, for example, when accompanying the use of a defined term in context.

As used herein, the terms “a,” “an,” and “the” mean one or more.

As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject. To be considered “compostable,” a material must meet the following four criteria: (1 ) the material should pass biodegradation requirement in a test under controlled composting conditions at elevated temperature (58°C) according to ISO 14855-1 (2012) which correspond to an absolute 90% biodegradation or a relative 90% to a control polymer, (2) the material tested under aerobic composting condition according to ISO16929 (2013) must reach a 90% disintegration ; (3) the test material must fulfill all the requirements on volatile solids, heavy metals and fluorine as stipulated by ASTM D6400 (2012), EN 13432 (2000) and ISO 17088 (2012); and (4) the material should not cause negative on plant growth.

As used herein, the term “biodegradable” generally refers to the biological conversion and consumption of organic molecules. Biodegradability is an intrinsic property of the material itself, and the material can exhibit different degrees of biodegradability, depending on the specific conditions to which it is exposed. The term “disintegrable” refers to the tendency of a material to physically decompose into smaller fragments when exposed to certain conditions. Disintegration depends both on the material itself, as well as the physical size and configuration of the article being tested. Ecotoxicity measures the impact of the material on plant life, and the heavy metal content of the material is determined according to the procedures laid out in the standard test method.

To be considered “biodegradable,” under home composting conditions according to the French norm NF T 51-800 and the Australian standard AS 5810, a material must exhibit a biodegradation of at least 90 percent in total (e.g., as compared to the initial sample), or a biodegradation of at least 90 percent of the maximum degradation of a suitable reference material after a plateau has been reached for both the reference and test item. The maximum test duration for biodegradation under home compositing conditions is 1 year.

To be considered “biodegradable,” under industrial composting conditions according to ASTM D6400 and ISO 17088, at least 90 percent of the organic carbon in the whole item (or for each constituent present in an amount of more than 1% by dry mass) must be converted to carbon dioxide by the end of the test period when compared to the control or in absolute. According to European standard ED 13432 (2000), a material must exhibit a biodegradation of at least 90 percent in total, or a biodegradation of at least 90 percent of the maximum degradation of a suitable reference material after a plateau has been reached for both the reference and test item. The maximum test duration for biodegradability under industrial compositing conditions is 180 days.

In order to be considered “biodegradable,” under soil composting conditions according the OK biodegradable SOIL conformity mark of Vingotte and the DIN Gepruft Biodegradable in soil certification scheme of DIN CERTCO, a material must exhibit a biodegradation of at least 90 percent in total (e.g., as compared to the initial sample), or a biodegradation of at least 90 percent of the maximum degradation of a suitable reference material after a plateau has been reached for both the reference and test item. The maximum test duration for biodegradability under soil compositing conditions is 2 years.

In one embodiment or in combination with any of the embodiments mentioned herein, the biodegradable cellulose acetate foam or article is industrial compostable or home compostable. In one subclass of this class, the foam or article is industrial compostable. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 6 mm. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 3 mm. In one sub-subclass of this subclass, the article has a thickness that is less than 1 .1 mm. In one subclass of this class, the foam or article is home compostable. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 6 mm. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 3 mm. In one subsubclass of this subclass, the foam or article has a thickness that is less than 1 .1 mm. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 0.8 mm. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 0.6 mm. In one sub-subclass of this subclass, the foam or article has a thickness that is less than 0.4 mm. In one embodiment or in combination with any of the embodiments mentioned herein, the thickness of the foam or article is from 1 to 10 mm, from 1 to 8 mm, from 2 to 8 mm, from 3 to 7 mm, from 4 to 6 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, or about 8 mm. However, it should be noted that the foam or article may have other, larger sizes. For example, in some embodiments, the foam or article may have a thickness from 0.5 to 24 inches, from 1 to 15 inches, or 3 to 12 inches.

In one embodiment or in combination with any of the embodiments mentioned herein, the foam or article exhibits greater than 90% disintegration after 12 weeks according to A Disintegration Test Protocol, as described in the specification, or in the alternative according to ISO 16929 (2013).

The compositions used to prepare the biodegradable cellulose acetate foams can comprise other additives such as fillers, stabilizers, odor modifiers, waxes, compatibilizers, biodegradation promoters, dyes, pigments, colorants, lubricants, anti-oxidants, viscosity modifiers, antifungal agents, heat stabilizers, antibacterial agents, softening agents, mold release agents, UV absorbers, and combinations thereof. Each additional additive may be present in the cellulose ester-based material in an amount less than 10 wt. %, less than 5 wt. % less than 4 wt. %, less than 3 wt. %, less than 2 wt. %, or less than 1 .0 wt. %. It should be noted that the same type of compounds or materials can be identified for or included in multiple categories of components in the cellulose acetate compositions. For example, polyethylene glycol (PEG) could function as a plasticizer or as an additive that does not function as a plasticizer, such as a hydrophilic polymer or biodegradation promotor, e.g., where a lower molecular weight PEG has a plasticizing effect and a higher molecular weight PEG functions as a hydrophilic polymer but without plasticizing effect.

In one embodiment or in combination with any other embodiment mentioned herein, the foam, composition or foamable composition further comprises a photodegradation catalyst. In one class of this embodiment, the photodegradation catalyst is a titanium dioxide, or an iron oxide. In one subclass of this class, the photodegradation catalyst is a titanium dioxide. In one subclass of this class, the photodegradation catalyst is an iron oxide.

In one embodiment or in combination with any other embodiment mentioned herein, the foam, composition, or foamable composition further comprises a pigment. In one class of this embodiment, the pigment is a titanium dioxide, a carbon black, or an iron oxide. In one subclass of this class, the pigment is a titanium dioxide. In one subclass of this class, the pigment is a carbon black. In one subclass of this class, the pigment is an iron oxide. In one subclass of this class, the pigment is a biodegradable particulate natural filler.

CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS

The preferred forms of the invention described above are to be used as illustration only and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.

The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as it pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.

Claims

1 . A foamed tray formed from 50 to 99 wt. % cellulose ester, wherein said tray comprises at least one elongated reinforcing member, wherein said at least one elongated reinforcing member includes a primary reinforcing member that extends laterally across at least 20% of a width of said tray, and wherein said primary reinforcing member is positioned no more than 0.25 inches apart from a lateral centerline of said tray.

2. The foamed tray of claim 1 , wherein the tray is configured to support a food item.

3. The foamed tray of claim 1 or 2, wherein the tray is configured to be wrapped with a film.

4. The foamed tray of any of claims 1 to 3, wherein the tray is produced by thermoforming a sheet of cellulose ester foam.

5. The foamed tray of any of claims 1 to 4, wherein the tray is biodegradable.

6. The foamed tray of any of claims 1 to 5, wherein the cellulose ester is cellulose diacetate.

7. The foamed tray of any of claims 1 to 6, wherein the tray includes a plasticizer in an amount from about 2 wt. % to about 40 wt. %.

8. The foamed tray of claim 7, wherein the plasticizer comprises Triacetin.

9. The foamed tray of any of claims 1 to 8, wherein the at least one elongated reinforcing member includes at least three reinforcing members.

10. The foamed tray of claim 9, wherein the at least three reinforcing members include the primary reinforcing member, a first supplemental reinforcing member, and a second supplemental reinforcing member, wherein the first and second supplemental reinforcing members are positioned on opposite sides, in a longitudinal direction, of the primary reinforcing member.

11 . The foamed tray of claim 1 , wherein the at least one elongated reinforcing member includes at least one longitudinally extending reinforcing member.

12. The foamed tray of claim 1 , wherein the at least one elongated reinforcing member includes at least one diagonally extending reinforcing member.

13. The foamed tray of claim 1 , wherein the at least one elongated reinforcing member includes at least one circularly-shaped reinforcing member.

14. The foamed tray of claim 1 , wherein the tray comprises a base and a raised rim extending around the base, wherein the at least one elongated reinforcing member comprises a raised rib that extends above a top surface of the base.

15. The foamed tray of claim 14, wherein the at least one elongated reinforcing member extends above the top surface of the base of the foamed tray from 2 to 10 mm.

16. The foamed tray of claim 14, wherein the at least one reinforcing member interconnects the base and the rim of the tray.

17. The foamed tray of any of claims 1 to 16, wherein the tray has a width in the range of 5.08 to 35.56 cm and a length of 10.16 to 60.96 cm.

18. The foamed tray of claim 17, wherein the tray has a height from

2.54 to 7.62 cm.

19. The foamed tray of any of claims 1 to 18, wherein a thickness of the tray is from 1 to 10 mm.

20. The foamed tray of any of claims 1 to 19, wherein the tray has a density less than 0.20 g/cm³.

21 . A process for making a foamed tray, said process comprising:

(a) extruding a mixed composition comprising cellulose ester to form a foamed sheet, wherein the cellulose ester is present in an amount from about 50 wt. % to about 99 wt. %;

(b) thermoforming the foamed sheet to form the foamed tray, wherein the tray comprises at least one elongated reinforcing member, wherein said at least one reinforcing member includes a primary reinforcing member that extends laterally across at least 20% of a width of the tray, and wherein said primary reinforcing member is positioned no more than 0.25 inches apart from a lateral centerline of the tray.

22. The process of claim 21 , wherein the tray is biodegradable.

23. The process of claim 21 or 22, wherein the cellulose ester is cellulose diacetate, wherein the mixed composition includes a plasticizer present in an amount from about 2 wt. % to about 40 wt. %, and wherein the plasticizer comprises Triacetin.

24. The process of any of claims 21 to 24, wherein the at least one elongated reinforcing member includes at least three reinforcing members, wherein the at least three reinforcing members include the primary reinforcing member, a first supplemental reinforcing member, and a second supplemental reinforcing member, wherein the first and second supplemental reinforcing members are positioned on opposite sides, in a longitudinal direction, of the primary reinforcing member.

25. The process of claim 21 , wherein the at least one reinforcing member includes at least one longitudinally extending reinforcing member.

26. The process of claim 21 , wherein the at least one elongated reinforcing member includes at least one diagonally extending reinforcing member.

27. The process of claim 21 , wherein the at least one elongated reinforcing member includes at least one circularly-shaped reinforcing member.

28. The process of claim 21 , wherein the tray comprises a base and a raised rim extending around the base, wherein the at least one elongated reinforcing member comprises a raised rib that extends above a top surface of the base, wherein the at least one elongated reinforcing member extends above the top surface of the base of the foamed tray from 2 to 10 mm.

29. The process of any of claims 21 to 28, wherein the tray has a width from 2 to 12 inches, a length from 4 to 24 inches, and a height from 1 to 3 inches.

30. The process of any claims 21 to 29, wherein a thickness of the tray is from 1 to 10 mm, and wherein the tray has a density less than 0.20