Cellulose ester foam articles

Abstract

A tray containing cellulose ester. The tray is configured such that it exhibits a weight increase of less than 10% when subjected to a 1-hour water absorption test as described herein.

Description

Background Art

[0001] Many foamed products, such as food packaging supplies, are intended to be disposable items that are discarded after use. One commercially important material used to make foamed products is polystyrene. However, polystyrene cannot be composted or biodegraded. Furthermore, some municipalities, states, and countries have implemented or are considering implementing bans on the use of polystyrene foams. Therefore, it is desirable to find alternative materials for use in foamed products, as well as promising compositions, methods, and systems for manufacturing such products.

Summary of the Invention

[0002] In one embodiment, or in combination with any other embodiment referred to herein, a tray comprising a cellulose ester is provided. The tray is configured such that when subjected to a 1-hour water absorption test as described herein, a weight gain of less than 10% is observed.

[0003] In another embodiment, or in combination with any other embodiment referred to herein, a foamed article formed from a foaming material comprising a cellulose ester and at least one plasticizer is provided. The foaming material is industrially compostable according to ASTM D6400, thereby showing at least 90 percent disintegration within 12 weeks when measured according to ISO 16929 (2013) at a high temperature of 58 °C ± 2 °C. The foaming material is home compostable according to the French standard NF T 51-800, thereby showing at least 90 percent disintegration within 2 weeks when measured according to ISO 16929 (2013) at an ambient temperature of 28 °C ± 2 °C.

[0004] In another embodiment, or in combination with any other embodiment referred to herein, a thermoformed foamed article comprising a cellulose ester and a plurality of cells formed therein is provided. At least 50% of the plurality of cells have a cross-sectional aspect ratio of 1:2 to 2:1.

[0005] In another embodiment, or in combination with any other embodiment referenced herein, a method for forming a foamed article is provided. This method includes the step of producing a foamed sheet from a composition comprising a cellulose ester. An additional step includes thermoforming the foamed sheet to form a foamed article having a certain article density. The article density is 0.095 g / cm³. 3 The following applies:

[0006] In another embodiment, or in combination with any other embodiment referenced herein, a method for forming a foamed article is provided. This method includes the step of producing a foamed sheet from a composition comprising a cellulose ester having a certain sheet density. An additional step includes thermoforming the foamed sheet to form a foamed article having a certain article density, which is at least 20% lower than the sheet density.

[0007] In another embodiment, or in combination with any other embodiment referenced herein, a method for forming a foamed article is provided. This method comprises producing a foamed sheet from a composition comprising a cellulose ester and a physical blowing agent. An additional step comprises thermoforming the foamed sheet to thereby form a foamed article having less than 1% by weight of the physical blowing agent 24 hours after thermoforming. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a biodegradable product molding process according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing another biodegradable product molding process according to an embodiment of the present invention. [Figure 3] This is a schematic diagram showing an extrusion section that can be used in the article molding process of Figure 1 and / or Figure 2 according to an embodiment of the present invention. [Figure 4]This is a schematic diagram showing another extrusion section that can be used in the article molding process of Figures 1 and 2 according to embodiments of the present invention. [Figure 5] This is a schematic diagram showing a sheet molding section that can be used in the article molding process of Figure 1 and / or Figure 2 according to embodiments of the present invention. [Figure 6] This is a top view of a foamed article in the form of a food tray according to an embodiment of the present invention. [Figure 7A] This is a scanning electron microscope image of a cross-section of a cellulose ester foam sheet before thermoforming. [Figure 7B] This is a scanning electron microscope image of a cross-section of a cellulose ester foam sheet after thermoforming. [Modes for carrying out the invention]

[0009] The embodiments generally relate to methods, systems, and compositions for forming biodegradable particulate materials (e.g., pellets), foamed sheets, and articles. Figures 1 to 5 show exemplary processes including methods, systems, and compositions, which are described in more detail below.

[0010] Methods and Systems As shown in Figures 1 and 2, raw materials are introduced into a biodegradable polymer manufacturing process for producing biodegradable polymer materials. In one embodiment, or in combination with any other embodiment referred to herein, the biodegradable polymer material comprises one or more cellulose esters. The one or more cellulose esters may include cellulose acetate. In such embodiments, the raw materials may include pulp such as wood pulp and / or cotton pulp. The pulp may be dissolvable grade pulp and / or paper grade pulp. The cellulose in the pulp can be esterified, for example with acetic acid, to form biodegradable cellulose ester polymers such as cellulose acetate polymers.

[0011] Next, the biodegradable polymer material can be introduced into the compounding process. In this process, the biodegradable polymer material can be mixed with a plasticizer and optionally one or more other additives (e.g., stabilizers) to form a compound material containing a plasticized biodegradable polymer. Other additives may also be mixed with the polymer and plasticizer. For example, as shown in Figure 2, other materials (additives) may include, but are not limited to, stabilizers, physical blowing agents (multiple), chemical blowing agents (multiple) (and / or precursors), nucleating agents (multiple), surface modifying additives (multiple), pigments (multiple), fillers (multiple), and / or other additives (multiple). Mixing can be achieved by any known mixing technique, including but not limited to rolling in a cylindrical vessel, overhead stirring, sigma blade mixing, and tumbling.

[0012] The compounding process may include a particle formation process. The particle formation process may generally include mixing biodegradable polymer materials, plasticizers, and other additives to form a mixed composition, and forming particulate material from that composition. Specifically, the particle formation process may include a pelletizing process, and the particulate material may contain a number of pellets. The term “compounded CE material” means a cellulose ester material formed during the compounding process, which may include a mixture of cellulose esters, plasticizers, and other additives. Furthermore, such compounded CE material may take the form of particulate material or pellets. It should be understood that, as used herein, the terms “particle formation” or “particle formation process” may be the same as, or at least include, “pellet formation” or “pelletizing process.” In some embodiments, the particle formation process may include pelletizing in a water tank, pelletizing on an air-cooled belt, water pelletizing, solvent compounding, and the like.

[0013] In one embodiment, or in combination with any other embodiment referenced herein, plasticizers and other additives(s) may be mixed with cellulose esters by conventional melt compounding techniques. This technique involves mixing the cellulose esters with plasticizers and optionally other additives at appropriate temperatures and pressures in a twin-screw extruder equipped with appropriate mixing elements, to obtain a molten, uniformly combined cellulose ester mixture by the time the material is discharged from the extruder. The molten, compounded cellulose ester mixture may then be extruded through a die having an orifice approximately 2–6 mm in diameter to extrude strands. These strands may then be cooled with water (e.g., via underwater pelletizing) or air and cut at regular intervals to obtain uniform, desirable sizes and shapes called “pellets” or “granules.” While this specification describes a process for forming pelletized compounding materials, it will be understood that the compounding materials supplied to the foam sheet manufacturing process may be in any physical form (e.g., pellets, powders, granules, fibers) according to some embodiments. The term "compounded CE material" refers to a cellulose ester material formed during the compounding process, which may include a mixture of cellulose esters, plasticizers, and other additives. Furthermore, such compounded CE material may take the form of a molten mixture or particulate material (e.g., pellets, powders, granules, fibers, etc.).

[0014] Next, as described above, formulated CE materials containing pellets of plasticizable biodegradable polymers can be introduced into a foamed sheet manufacturing process, as shown in Figures 1 and 2. The foamed sheet manufacturing process may include one or more zones / steps for producing a foamed sheet or film, which are described in further detail below. While exemplary foamed sheet manufacturing processes are described herein, it should be understood that certain embodiments described herein may also be applicable to rigid (i.e., non-foamed) materials and articles. As shown in Figure 1, various additives can be introduced into one or more zones of the foamed sheet manufacturing process in one embodiment or in combination with any other embodiments referred to herein. Additives may include, but are not limited to, stabilizers, physical foaming agents (or more), chemical foaming agents (or more) (and / or precursors), nucleating agents (or more), surface modifying additives (or more), pigments (or more), fillers (or more), and / or other additives (or more).

[0015] A foamed sheet manufacturing process may generally include an extrusion section and a sheet forming section. An exemplary extrusion section is shown in Figure 3. As shown, the extrusion section may include a feed preparation zone where solid additives may be combined with the compounded CE material and introduced into the downstream extrusion zone. In one embodiment, or in combination with any other embodiment referred to herein, the feed preparation zone may include a feed hopper. Thus, the compounded CE material and other solid additives may be deposited in the feed hopper, which directs the combined feed composition towards the extrusion zone. The feed preparation zone may further include a mixer where the compounded CE material and one or more additives may be mixed before being introduced into the hopper. Mixing can be achieved by any known mixing technique, including but not limited to rolling in a cylindrical vessel, overhead stirring, sigma blade mixing, and tumbling. Examples of solid additives that can be combined with the formulation materials include chemical blowing agents, nucleating agents, surface modifiers, pigments, fillers, and / or other additives.

[0016] Next, the combined feed composition from the feed preparation zone may be introduced into the extrusion zone. The extrusion zone may generally include 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 the extruder barrel and conveyed by a screw(s) through a die that forms an extruder from the feed composition. As the composition is conveyed through the extruder barrel toward the die, it may be heated and at least partially melted. Thus, the term “CE molten composition” is used herein to mean a cellulose ester-based feed composition melted into a fluid molten resin through the extrusion section. Heating may be supplied by an external heater positioned along the outside of the extruder barrel. The shape of the extruder is generally determined by the shape and size of the die head. The extruder may be further shaped by downstream processes as described below.

[0017] One or more additives can be introduced into the CE molten resin while it is in the extruder. For example, one or more physical blowing agents can be added to the CE molten resin by injecting a physical blowing agent into the composition being conveyed in the extruder barrel.

[0018] As shown in Figure 4, in one embodiment, or in combination with any other embodiment referred to herein, the extrusion zone may include a primary extrusion vessel and a cooling vessel. The primary extrusion vessel and the cooling vessel may be separate devices or may be combined as an integrated device. In any case, the supply composition from the supply preparation zone is introduced into the primary extrusion vessel and at least partially melts as it is conveyed through the extruder barrel as described above, thereby producing molten CE resin. The molten CE resin exiting the primary extrusion vessel may have a temperature of about 220°C to about 240°C. One or more additives, such as blowing agents, may be added to the molten CE resin as it is conveyed through the primary extrusion vessel.

[0019] Next, the molten CE resin from the primary extrusion vessel is introduced into a cooling vessel. The cooling vessel may be a secondary extrusion vessel that operates similarly to the primary extrusion vessel but at a lower temperature. In the cooling vessel, the molten CE resin can be further mixed to provide a substantially homogeneous mixture of the molten polymer and other additives(s). The molten CE resin can then be passed through a die and directed outward from the die head to obtain a cellulose ester-based extruder, which can be further processed in the sheet forming section of a foamed sheet manufacturing process. In one embodiment, or in combination with any other embodiment referred to herein, the molten CE 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, about 150°C to about 220°C, and / or about 170°C to about 200°C.

[0020] As shown in Figure 4, one or more filtration devices may be installed within the extrusion section to filter and remove particulate matter from the molten CE resin. For example, a screen changer filtration device may be installed downstream of the primary and secondary extrusion vessels, thereby removing solid components from the molten CE resin before it passes through the die head to the sheet molding section.

[0021] The sheet forming section may include any of a variety of systems and processes for forming extruded sheets from cellulose ester material that can be used for article forming. The shape of the extruded sheet is generally determined by the shape of the die head, but the shape of the sheet formed in the sheet forming section may be determined by the shape of the die head and other downstream processes. For example, the extruded sheet may generally have a flat shape, or it may be annular and subject to further processing to form a flat sheet. In embodiments where the die is annular, the die may have diameters of 1 to 40 cm, 2 to 20 cm, 2 to 10 cm, and / or 3 to 8 cm. Furthermore, the thickness of the opening from which the extruded sheet is discharged, referred to herein as the “die gap,” may generally be 0.1 to 6.0 mm, 0.1 to 3.0 mm, and / or 0.1 to 1.0 mm in size.

[0022] An exemplary sheet molding section is shown in Figure 5. As illustrated, the molten CE resin is extruded through an annular die and stretched on a molding mandrel. A cooling fluid (e.g., air) can be flowed inside and / or outside the extruded material to cool it as it passes over the mandrel. For example, the cooling fluid can be blown from the mandrel towards the die to cool the inner surface of the extruded material between the die and the mandrel. Additionally or alternatively, the cooling fluid can be flowed across the mandrel to cool the outer surface of the extruded material as it passes over the mandrel.

[0023] A slicer (or cutting device) can be used to open up a tubular extruder, which allows the tubular shape to be formed into a flat sheet. For example, a tubular extruder passing over a mandrel may be cut open and pulled to a tension station containing one or more rollers. These rollers flatten the extruder and maintain the amount of tension required to keep the extruder pulled over the mandrel. The flattened extruder is generally in the form of a sheet, which may then be directed to a winding station, where the material may be wound for packaging and transport.

[0024] Referring again to Figures 1 and 2, the sheets produced by the sheet manufacturing process can be used to form foamed products. Foamed products will be described in more detail below. Such articles are particularly useful in the food service industry. An exemplary article is a meat tray. This article may have one or more particularly advantageous properties. For example, the article may be biodegradable and / or compostable, and / or may have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0025] composition The process described above may include the preparation and extrusion of compositions that can be used in downstream processing to form useful articles. For example, in one embodiment, or in combination with any other embodiment referred to herein, the extrusion feed material may include particulate material comprising a biodegradable polymer, a plasticizer, and optionally one or more additives, such as those described herein. In one embodiment, or in combination with any other embodiment referred to herein, the feed material can be combined with one or more additives, such as those described herein, to provide a mixed composition comprising a biodegradable polymer, a plasticizer, and one or more additives. In one embodiment, or in combination with any other embodiment referred to herein, the biodegradable polymer comprises a cellulose ester. Further details of composition components comprising a biodegradable polymer (e.g., a cellulose ester), a plasticizer, and other additives are shown below.

[0026] Cellulose ester The cellulose esters used as described herein may be any known in the art. Cellulose esters that can be used in the embodiments herein generally contain repeating units of the following structure: [ka] In the formula, R1, R2, and R3 are independently selected from the group consisting of hydrogen, acetyl, propyl, or butyl. The substitution level of a cellulose ester is usually expressed in terms of the degree of substitution ("DS"), which is the average number of non-OH substituents per anhydrous glucose unit ("AGU"). Generally, conventional cellulose contains three hydroxyl groups in each substituteable AGU unit. Therefore, DS can have values ​​from 0 to 3. Natural cellulose is a large polysaccharide with a degree of polymerization of 250 to 5,000 even after pulping and purification, and therefore the assumption that the maximum DS is 3.0 is approximately correct. Since DS is a statistical mean, a value of 1 does not guarantee that every AGU has only one substituent. In some cases, unsubstituted anhydrous glucose may exist, some with two substituents, some with three, and the value is usually a non-integer. Total DS is defined as the average number of all substituents per anhydrous glucose unit. The degree of substitution per AGU can also mean specific substituents, such as hydroxyl or acetyl, for example. In one embodiment, or in combination with any other embodiment, n is an integer in the range of 25 to 250, or 25 to 200, or 25 to 150, or 25 to 100, or 25 to 75.

[0027] In one embodiment, or in combination with any other embodiment, a cellulose ester may have at least two anhydrous glucose rings and at least 50 to a maximum of 5,000 anhydrous glucose rings, or at least 50 to less than 150 anhydrous glucose rings. The number of anhydrous glucose 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, a cellulose ester may have an intrinsic 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, measured at a temperature of 25°C for 0.25 grams of sample in 100 ml of a 60 / 40 wt solution of phenol / tetrachloroethane. In one embodiment, or in combination with any other embodiment, cellulose esters useful herein may have a DS / AGU of about 1 to about 3.0, about 2.2 to about 2.8, or 1 to less than 2.2, or 1 to less than 1.5, where the substituted ester is acetyl.

[0028] Cellulose esters can be produced by any method known in the art. An example of a cellulose ester production process is 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 from a variety of grades and sources, including, among others, cotton linters, softwood pulp, hardwood pulp, corn fiber, and other agricultural sources, as well as bacterial cellulose.

[0029] One method for producing cellulose esters involves esterification of cellulose by mixing it with a suitable organic acid, acid anhydride, and catalyst. The cellulose is then converted to cellulose triester. Next, the cellulose triester can be hydrolyzed by adding a water-acid mixture, and then filtered to remove gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester may then be washed with water to remove reaction by-products, followed by dehydration and drying.

[0030] The hydrolyzed cellulose triesters may 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 homogeneous acylation of cellulose dissolved in a suitable solvent such as LiCl / DMAc or LiCl / NMP.

[0031] Those skilled in the art will understand that the commercial term "cellulose triester" also includes cellulose esters that are not completely substituted with acyl groups. For example, cellulose triacetate commercially available from Eastman Chemical Company, Kingsport, TN, USA, typically has a DS of about 2.85 to about 2.99.

[0032] After esterification of cellulose to triester, some of the acyl substituents may be removed by hydrolysis or alcohol decomposition to obtain a secondary cellulose ester. As mentioned earlier, the distribution of acyl substituents may be random or non-random depending on the specific method used. Alternatively, the secondary cellulose ester may be prepared directly without hydrolysis by using a limited amount of acylation reagent. This process is particularly useful when the reaction is carried out in a solvent that dissolves cellulose. All of these methods yield cellulose esters useful in the present invention.

[0033] In one embodiment, or in combination with any of the embodiments mentioned, the cellulose acetate is a cellulose diacetate having a polystyrene-equivalent number-average molecular weight (Mn) of about 10,000 to about 100,000, as measured by gel permeation chromatography (GPC) using NMP as the solvent and polystyrene-equivalent Mn according to ASTM D6474. In one embodiment, or in combination with any other embodiment, the cellulose acetate composition, when measured by gel permeation chromatography (GPC) according to ASTM D6474 using NMP as the solvent, has a range of 10,000 to 90,000, or 10,000 to 80,000, or 10,000 to 70,000, or 10,000 to 60,000, or less than 10,000 to 60,000, or less than 10,000 to 55,000, or 10,000 to 50,000, or less than 10,000 to 50,000, or less than 10,000 to 45,000, or 10,000 to 40,000, or 10,000 to 30,000, or 20,000. 00 to less than 60,000, or 20,000 to less than 55,000, or 20,000 to less than 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 60,000 It contains cellulose diacetate having a polystyrene-equivalent number-average molecular weight (Mn) of less than 00, or between 30,000 and less than 55,000, or between 30,000 and less than 50,000, or between 30,000 and less than 45,000, or between 30,000 and 40,000, or between 30,000 and 35,000.

[0034] The most common commercially available secondary cellulose esters are produced by forming cellulose triesters through the initial heterogeneous acylation of cellulose using an acid catalyst. After obtaining a homogeneous solution of the cellulose triester in the corresponding carboxylic acid, the cellulose triester is then subjected to hydrolysis until the desired degree of substitution is obtained. After isolation, random secondary cellulose esters are obtained, i.e., the relative degree of substitution (RDS) at each hydroxyl group is approximately equal.

[0035] The cellulose esters useful in the present invention can be prepared using techniques known in the art, and can also be selected from various types of cellulose esters available from, for example, Eastman Chemical Company, Kingsport, TN, USA, such as Eastman® Cellulose Acetate CA398-30 and Eastman® Cellulose Acetate CA398-10, Eastman® CAP485-20 Cellulose Acetate Propionate, and Eastman® CAB381-2 Cellulose Acetate Butyrate.

[0036] In one embodiment, or in combination with any other embodiment, cellulose esters can be prepared by converting cellulose to cellulose esters using a reactant obtained from a recycled material, such as a recycled plastic-containing synthesis gas source. In one embodiment, or in combination with any other embodiment, such reactant may be a cellulose reactant comprising an organic acid and / or acid anhydride used in a cellulose esterification or acylation reaction, such as those discussed herein.

[0037] One embodiment of the present invention provides a cellulose ester composition comprising at least one regenerated cellulose ester, or in combination with any of the embodiments described herein, wherein the cellulose ester has at least one substituent on anhydrous glucose units (AU) derived from a regenerated material (e.g., recycled plastic-containing synthesis gas).

[0038] In one embodiment, or in combination with any other embodiment, the cellulose ester composition contains 50-99% by weight, or 60-99% by weight, or 70-99% by weight, or 80-99% by weight, or 90-99% by weight, 50-90% by weight, or 60-90% by weight, or 70-90% by weight, or 80-90% by weight, or 90-99% by weight, or 50-80% by weight, or 60-80% by weight, or 70-80% by weight, or 50-70% by weight, or 60-70% by weight, or 50-60% by weight, based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein may include a combination, blend, or mixture of two or more different types of cellulose esters. For example, in some embodiments, the cellulose ester used herein may consist of a blend of two or more cellulose esters having different DSACs. However, this blend may have a total DSAC of 2.2-2.8.

[0039] plasticizer In one embodiment, or in combination with any other embodiment, the cellulose ester compositions described herein may contain at least one plasticizer. The plasticizer reduces the melting temperature, i.e., Tg, and / or melt viscosity of the cellulose ester. Cellulose ester plasticizers include glycerol triacetate (triacetin), glycerol diacetate (diacetin), dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, polyethylene glycol (molecular weight 200-600), dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl o-benzoyl benzoate, triethylene glycol dipropionate, 1,2-epoxypropylphenylethylene glycol, 1,2-epoxypropyl (m-cresyl)ethylene glycol, 1,2-epoxypropyl (o-cresyl)ethylene glycol, β-oxyethylcyclohexene carboxylate, bis(cyclohexanate)diethylene glycol, triethyl citrate, polyethylene glycol, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, tributyl acetyl citrate, Admex, trippropionine, Scandiflex, poloxamer copolymer, and poly Ethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and glycol tribenzoate, benzoate-containing plasticizers such as the Benzoflex® plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, o-cresyl p-toluenesulfonate, n-ethyltoluenesulfonamide, adipate-based plasticizers, soybean oil epoxides such as the Paraplex® plasticizer series, sucrose-based plasticizers, di Possible materials include butyl sebacate, tributylin, sucrose acetate isobutyrate, Resolflex® series plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (ethylphthalyl ethyl glycolate "EPEG" and methylphthalyl ethyl glycolate "MPEG"), methoxypolyethylene glycol, 2,2,4-trimethylpentane-1,3-diirbis(2-methylpropanoate), and polycaprolactone.In some embodiments, the plasticizers used herein may include a combination or mixture of two or more different types of plasticizers.

[0040] In one embodiment, or in combination with any other embodiment, the plasticizer is a food-compatible plasticizer. Food compatibility means that it complies with applicable food additive and / or food contact regulations, and the plasticizer is permitted for use or recognized as safe by at least one (national or regional) food safety regulatory authority (or organization), for example, listed in the 21 CFR Food Additive Regulations, or otherwise recognized by the U.S. FDA with a Certificate of Gravity for Use (GRAS). In one embodiment, or in combination with any other embodiment, the food-compatible 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, possible examples of food-compatible plasticizers include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, tributyl acetyl citrate, Admex, trippropionine, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and glycol tribenzoate.

[0041] In one embodiment, or in combination with any other embodiment, the plasticizer may be present in an amount sufficient to enable the cellulose ester composition to be melt-processed (or thermoformed) in a conventional melt-processing apparatus to produce useful articles, such as disposable plastic products. In one embodiment, or in combination with any other embodiment, the plasticizer may be present in an amount of 1 to 40% by weight, or 5 to 25% by weight, or 10 to 25% by weight, or 12 to 20% by weight, based on the weight of the cellulose ester composition, for most thermoplastic processing. In one embodiment, or in combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be achieved with plasticizer levels ranging from 10 to 30%, or 12 to 25%, or 15 to 20%, or 10 to 25% by weight, based on the weight of the cellulose ester composition.

[0042] 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, benzoic acid-containing plasticizers such as the Benzoflex® plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, adipic acid-based plasticizers, soybean oil epoxides such as the Paraplex® plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributylin, plasticizers in the Resolflex® series, triphenyl phosphate, glycolic acid, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diirbis(2-methylpropanoate), and polycaprolactone.

[0043] In one embodiment, or in combination with any other embodiment, the cellulose ester composition may contain a plasticizer selected from the group consisting of PEG and MPEG (methoxyPEG). The polyethylene glycol or methoxy polyethylene glycol composition has an average molecular weight of 200 to 600 daltons, and the composition is melt-workable, biodegradable, and disintegrable.

[0044] In one embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol or methoxyPEG having an average molecular weight of 300 to 550 daltons.

[0045] In one embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol having an average molecular weight of 300 to 500 daltons.

[0046] In one embodiment, or in combination with any other embodiment, the cellulose ester composition contains at least one plasticizer (as described herein) in an amount based on the total weight of the cellulose ester composition of 1-40% by weight, or 5-40% by weight, or 10-40% by weight, or 12-40% by weight, 13-40% by weight, or 15-40% by weight, or more than 15-40% by weight, or 17-40% by weight, or 20-40% by weight, or 25-40% by weight, or 5-35% by weight, or 10-35% by weight, or 13-35% by weight, or 15-35% by weight, or more than 15-35% by weight, or 17-35% by weight, or 20-35% by weight, or 5-30% by weight, or 10-30% by weight. , or containing in amounts of 13-30% by weight, or 15-30% by weight, or more than 15-30% by weight, or 17-30% by weight, or 5-25% by weight, or 10-25% by weight, or 13-25% by weight, or 15-25% by weight, or more than 15-25% by weight, or 17-25% by weight, or 5-20% by weight, or 10-20% by weight, or 13-20% by weight, or 15-20% by weight, or more than 15-20% by weight, or 17-20% by weight, or 5-17% by weight, or 10-17% by weight, or 13-17% by weight, or 15-17% by weight, or more than 15-17% by weight, or less than 5-17% by weight, or less than 10-17% by weight, or less than 13-17% by weight, or less than 15-17% by weight.

[0047] In one embodiment, or in combination with any other embodiment, at least one plasticizer includes or is a food-grade plasticizer or an FDA-approved plasticizer. The food-grade plasticizer or FDA-approved plasticizer includes or is triacetin or PEG (MW300-500).

[0048] Biodegradable polymers In one embodiment, or in combination with any other embodiment, the cellulose ester composition described herein comprises a BCE component comprising at least one biodegradable cellulose ester (BCE) which may comprise one or more of the cellulose esters described herein, and a biodegradable polymer component comprising at least one other biodegradable polymer (other than BCE). In one embodiment, or in combination with any other embodiment, the other biodegradable polymer can be selected from polyhydroxyalkanoates (PHA and PHB), polylactic acid (PLA), polycaprolactone polymer (PCL), polybutylene adipate terephthalate (PBAT), polyethylene succinate (PES), polyvinyl acetate (PVA), polybutylene succinate (PBS) and copolymers (such as polybutylene succinate-co-adipate (PBSA)), cellulose esters, cellulose ethers, starch, proteins, their derivatives, 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 BCE) in an amount of 0.1 to less than 50% by weight, or 1 to 40% by weight, or 1 to 30% by weight, or 1 to 25% by weight, or 1 to 20% by weight, 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 BCE) in an amount of 0.1 to less than 50% by weight, or 1 to 40% by weight, or 1 to 30% by weight, or 1 to 25% by weight, or 1 to 20% by weight, based on the total amount of BCE and biodegradable polymer.In one embodiment, or in combination with any other embodiment, at least one biodegradable polymer has a weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC) with methylene chloride as the solvent using a refractive index detector and a polystyrene standard, which is 10,000 to 1,000,000, or 50,000 to 1,000,000, or 100,000 to 1,000,000, or 2 The PHA comprises a range of 50,000 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. In one embodiment, or in combination with any other embodiment, the PHA may comprise polyhydroxybutyrate-co-hydroxyhexanoate.

[0049] Nuclear agent A nucleating agent refers to a chemical or physical material that provides sites for cell formation in a mixture of molten formulations, such as within a molten CE resin. As will be described in more detail below, nucleating agents can be added to the formulated CE material during the formulation process. Alternatively, or in addition, nucleating agents may be added during the manufacturing process of the foamed sheet. For example, a nucleating agent may be blended with the formulation introduced into the hopper of the extruder in the extrusion section. Alternatively, a nucleating agent may be added to the molten CE resin in the extruder itself. Examples of nucleating agents include physical nucleating agents and chemical nucleating agents. A physical nucleating agent is a substance that is immiscible with the polymer matrix of the molten CE resin at the extrusion temperature of the extrusion section. A chemical nucleating agent is a substance that reacts (e.g., decomposes) during extrusion (e.g., at the extrusion temperature in the extruder) to form a physical nucleating agent. Thus, a chemical nucleating agent may be considered (referred to herein as a precursor) of a physical nucleating agent formed in situ.

[0050] Suitable physical nucleating agents include fine particles having a desired particle size and / or shape to create cell nucleation sites within the CE molten resin. For example, in some embodiments, the physical nucleating agent has an average 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 micron. However, in some other embodiments, it may be preferable to have nanoscale-sized particles. Furthermore, in some embodiments, the physical nucleating agent preferably has a high aspect ratio (i.e., width:height). For example, in some embodiments, the physical nucleating agent has an average aspect ratio 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, as described above, the physical nucleating agent must be immiscible with the polymer matrix of the CE molten resin at the extrusion temperature of the extrusion section. Therefore, in some embodiments, the physical nucleating agent needs to have a melting temperature of at least 220°C, at least 230°C, 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. However, the physical nucleating agent may be selected to have the ability to recrystallize after cooling following melting.

[0051] Examples of suitable inorganic physical nucleating agents include, but are not limited to, talc, minerals such as CaCO3 and mica, and mixtures of at least two of the above. One representative example is Heritage Plastics HT6000 linear low-density polyethylene (LLDPE) based talc concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon dioxide, titanium dioxide, magnesium oxide, aluminum oxide and calcium silicate, barium sulfate, kaolin, aluminum trihydrate ATH (Al(OH)3), MDH (Mg(OH)2), diatomaceous earth, magnetite / hematite, halloysite, zinc oxide, and titanium dioxide. In some embodiments, the inorganic nucleating agent includes oxides such as metal oxides or mixed metal oxides, 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 dioxide, and titanium dioxide. In other embodiments, the inorganic nucleating agent includes silicates such as magnesium silicate and calcium silicate, selected from one or more of the following:

[0052] Biodegradable natural particulate matter derived from renewable organic sources (e.g., organic nucleating agents) has also been found to function as effective physical nucleating agents. Natural substances that can be physical nucleating agents include substances composed of cellulose fibers and / or cellulose starch. Examples, but not limited to, include almond husk powder, animal fiber, apricot husk powder, bamboo powder, bark powder, shell powder, coconut husk powder, coconut fiber, cork powder, corn cob powder, corn cob grit, cottonseed husks, flocs and fibers, hazelnut husk powder, kenaf powder, natural fiber, nut shells and powders, oat fiber powder, olive stone powder, peanut shell powder, pecan husk powder, pine nut husk powder, pistachio nut husk powder, plant fiber, rice husk powder, rice husk grit, rice husks, soybean powder, starch powder (hydrophobic), walnut husk powder, wheat husk, wheat hull, and wood powder. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, metal stearate, carbon black, and dolomite.

[0053] As described above, a suitable chemical nucleating agent (or a precursor to a physical nucleating agent formed in situ) is configured to decompose when a threshold chemical reaction temperature is reached, generating cell nucleating sites in the CE molten resin. These small cells serve as nucleating sites for the proliferation of larger cells from physical or other types of blowing agents. In some embodiments, the precursor is configured to form a gas such as CO2 or N2 during the extrusion of the particulate material.

[0054] Examples of chemical nucleating agents include, but are not limited to, acids such as citric acid or citric acid-based materials. Other acids may include lauric acid, stearic acid, tartaric acid, ascorbic acid, propionic acid, and hexanoic acid. A typical example is HYDROCEROL™ CF-40E (available from Clariant Corporation), which contains citric acid and a nucleating agent. In some embodiments, the chemical nucleating agent includes a combination of acid and base, such as a carbonate, and examples of carbonates include sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate. For example, a typical example of a chemical nucleating agent is a combination of citric acid and sodium bicarbonate. In some embodiments, the chemical nucleating agent may include a carrier in which the active ingredient of the nucleating agent is dispersed. For example, yet another typical example of a chemical nucleating agent is a combination of citric acid, sodium bicarbonate, and a carrier. In some embodiments, the carrier may include polystyrene. However, the carrier may include other compositions such as various biopolymers (e.g., polybutylene succinate, Capa polyester, etc.), polyolefins, and acrylic copolymers (e.g., ethylene methyl acrylate). In some such embodiments, citric acid and sodium bicarbonate may constitute about half (by weight) of the chemical nucleating agent, while the carrier constitutes the remaining half (by weight). Furthermore, in some such embodiments, there may be more sodium bicarbonate than citric acid in the chemical nucleating agent. For example, there may be about three times (by weight) more sodium bicarbonate than citric acid in the chemical nucleating agent. It should also be understood that in some embodiments, such as when the nucleating agent is hecofoam or hydrocerol, a carrier may not be required or used.

[0055] In one embodiment or in combination with any of the embodiments referenced herein, the nucleating agents are present in amounts of 0.1 to 10% by weight, 0.1 to 5.0% by weight, at least 0.1% by weight, at least 0.25% by weight, at least 0.5% by weight, at least 1.0% by weight, at least 1.25% by weight, at least 1.5% by weight, at least 1.75% by weight, at least 2.0% by weight, at least 2.25% by weight, at least 2.5% by weight, at least 2.75% by weight, or at least 3.0% by weight, or at least 3.5% by weight, or at least 4.0% by weight, or at least 4.5% by weight, and / or less than 7.5% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, or less than 1.0% by weight, based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agents used herein may include combinations or mixtures of two or more different types of nucleating agents.

[0056] It should be noted that cellulose ester materials, whether in the form of compounded CE material or CE molten resin, can generally tolerate a maximum amount of nucleating agent that can function to form nucleating sites. Any remaining nucleating agent added to the cellulose ester material remains as a filler. Depending on the type of filler used, the filler can provide various properties to the resulting cellulose ester foam and / or article. For example, some fillers can increase / decrease the density, ductility, Young's modulus, yield strength, thermal deflection temperature, permeability, impact resistance, elongation to break, adhesive properties, and biodegradability of the cellulose ester material. Fillers can also be used to alter the visual properties (e.g., color, opacity, etc.) and tactile properties (e.g., material continuity, surface roughness, etc.) of the cellulose ester material.

[0057] foaming agent A blowing agent refers to a physical or chemical material (or combination of materials) that acts to expand nucleating sites. Blowing agents may include chemical blowing agents, physical blowing agents, combinations thereof, or several types of chemical and physical blowing agents. Blowing agents function to reduce the density of the material by expanding the cells formed in the molten mixture at the nucleating sites. Blowing agents may be added to the CE molten resin in the extruder. It has been surprisingly discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture, carrying the absorbed water into the molten resin mixture, where it can act as a physical blowing agent.

[0058] Examples of physical blowing agents include H2O, N2, CO2, alkanes, alkenes, ethers, ketones, argon, helium, air, or mixtures thereof. Furthermore, it has been surprisingly discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture, transport the absorbed water into the molten resin mixture, where it can act as a physical blowing agent. Hygroscopic and biodegradable natural fillers can be incorporated into the composition to allow them to absorb moisture before the foaming process, after which the water is released and acts as a physical blowing agent. Beneficially, water can also be used as a plasticizer for cellulose ester resins. Additionally, in some embodiments, the physical blowing agent may include hydrocarbons such as pentane / isopentane or butane / isobutane. Other hydrocarbons may include propane, ethane, methane, hexane, cyclohexane, cyclopentane, or cyclobutene.

[0059] Chemical blowing agents are materials that decompose or react to produce gases (e.g., CO2 or N2). Such gases expand cells in the molten resin mixture and / or the resulting foam mixture, creating a structural material with multiple gaseous voids that are dispersed throughout. Chemical blowing agents can be endothermic or exothermic. Chemical blowing agents typically decompose and release gases at a certain temperature. Examples of chemical blowing agents include azodicarbonamides, acids (e.g., citric acid), and carbonates (e.g., sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, etc.), and combinations thereof.

[0060] In one embodiment, or in combination with any of the embodiments referenced herein, the foaming agent is present in an amount of 0.3 to 1.5% by weight, or 0.3 to 2.0% by weight, or 0.3 to 2.5% by weight, or 0.3 to 3.0% by weight, or 0.3 to 3.5% by weight, or 0.3 to 4.0% by weight, or 0.3 to 8%, or 1.3 to 1.5% by weight, or 1.3 to 2.0% by weight, based on the total weight of the cellulose ester composition. 1.3-2.5% by weight, or 1.3-3.0% by weight, or 1.3-3.5% by weight, or 1.3-4.0% by weight, or 1.3-4.5% by weight, or 1.3-5.0% by weight, or 1.3-5.5% by weight, or 1.5-3.0% by weight, or 1.5-4.0% by weight, or 1.5-5.0% by weight, or 1.5-6.0% by weight, or 2.0-3.0% by weight, or 2.0-4.0% by weight, or 2.0-5 0.0% by weight, or 2.0-6.0% by weight, or 2.5-3.0% by weight, or 2.5-4.0% by weight, or 2.5-5.0% by weight, or 2.5-6.0% by weight, or 3.0-4.0% by weight, or 3.0-5.0% by weight, or 3.0-6.0% by weight, or 0.0-9.0% by weight, or 0.5-9.0% by weight, or 1.0-9.0% by weight, or 1.5-9.0% by weight, or 2.0-9.0% by weight , or present in amounts of 2.5-9.0% by weight, or 3.0-9.0% by weight, or 3.5-9.0% by weight, or 4.0-9.0% by weight, or 4.5-9.0% by weight, or 5.0-9.0% by weight, or 5.5-9.0% by weight, or 6.0-9.0% by weight, or 6.5-9.0% by weight, or 7.0-9.0% by weight, or 7.5-9.0% by weight, or 8.0-9.0% by weight, or 8.5-9.0% by weight. In some embodiments, the blowing agent used herein may include a combination or mixture of two or more different types of blowing agents.

[0061] Surface modification additives Surface modifiers refer to materials that can be added to cellulose ester compositions to improve their processability, thereby modifying the structure of the composition (or the resulting foamed article). For example, the inventors of this application have found that adding surface modifiers to compounded CE materials (e.g., pellets in the compounding process) or CE molten resin (e.g., in the extrusion process) can improve processing by reducing undesirable adhesion of the CE molten resin to the die or mandrel (or other components in the foamed sheet manufacturing process). Such reduction in adhesion can be achieved by the surface modifier suppressing the fusion of cellulose esters caused by plasticizers. The addition of surface modifiers can also reduce blocking of cellulose ester foamed sheets produced in the sheet molding section. Furthermore, surface modifiers can also improve the foamed sheet manufacturing process by enabling the process to be carried out at lower temperatures.

[0062] Furthermore, in some embodiments, the surface modification additive may function as an antistatic additive to suppress electrical sparks or arc discharges in the molten CE resin. Suppression of electrical sparks or arc discharges can be particularly important to reduce the possibility of hydrocarbons igniting and causing a fire when hydrocarbons are used as blowing agents. Beneficially, the surface modification additive may also reduce the diffusion of blowing agents, such as hydrocarbons, from the foamed sheet or the resulting article. In some embodiments, hydrocarbons themselves can be used as surface modification additives.

[0063] Nevertheless, more common examples of surface modifiers that can be used with the compounded CE material (e.g., during the compounding process) or with the CE molten resin (e.g., during the foam sheet manufacturing process) according to embodiments of the present invention include fatty acids such as palmitic acid, tallow acid, stearic acid, oleic acid, linoleic acid and linolenic acid, arachidic acid / behenic acid, behenic acid, and erucic acid. Surface modifiers may also include fatty acid amides such as erucamide, oleoamide, stearamide, benamide, secondary amide, and bisamide.

[0064] Examples of additional surface modification additives may include glycerol esters and / or stearate esters such as monoglycerides, diglycerides, and triglycerides. Examples of monoglycerides include glycerol monostearate or monoglyceride derivatives (such as diacetyltartrate esters of mono and diglycerides (DATEM), ethoxylated monoglycerides, succinyl monoglycerides, and propylene glycol monoesters (PGME)). Examples of surface modification additives may also include metal stearate salts such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate, and / or combinations thereof (e.g., calcium stearate / zinc stearate). Examples of surface modifying additives include waxes such as polyolefin waxes (polypropylene wax and polyethylene wax), olefin oxide waxes, ethylene acrylic acid (EAA) copolymer waxes, ethylene methyl acrylate (EMA) copolymer waxes, EAA ionomer shafts, acrylic waxes, and / or natural waxes (such as rice bran wax, sunflower wax, sugarcane wax, candelilla wax, soybean wax, beeswax, caddelilla wax, and carnauba wax).

[0065] Other non-exclusive examples of surface modification additives include aliphatic diesters (e.g., dioctyl adipates), polyglycol diesters, alkylalkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters, and alkyl monoesters. Furthermore, various oils such as aromatic oils, naphthenic oils, glyceride oils, silicone oils, and epoxidized oils (e.g., soybean oil and linseed oil) can be used as surface modification additives. Thus, in some embodiments, the surface modification additive includes plasticizers such as aliphatic diester plasticizers and polyester plasticizers. Furthermore, in some embodiments, the surface modification additive may include polyhedral oligomeric silsesquioxanes (POSS).

[0066] More generally, the surface modification additive used in the embodiments of the present invention may have a lower polarity than the cellulose ester in the formulated CE material (e.g., during the formulation process) or the CE molten resin (e.g., during the foamed sheet manufacturing process). For example, the surface modification additive may have (based on the Hansen solubility parameter) a total solubility parameter δ of less than 25 MPa 1 / 2 less than 20 MPa 1 / 2 less than or 19.5 MPa 1 / 2 less than; a dispersive force solubility parameter δ of less than 18 MPa 1 / 2 less than 16 MPa 1 / 2 less than or 14 MPa 1 / 2 less than; and / or a bipolar intermolecular force solubility parameter δ of less than 12 MPa d ; 12 MPa 1 / 2 less than 8 MPa 1 / 2 less than or 4 MPa 1 / 2 less than; and / or a hydrogen bonding solubility parameter δ of less than 11 MPa d ; and / or 11 MPa 1 / 2 less than 10 MPa 1 / 2 less than or 9 MPa 1 / 2 less than; and / or a hydrogen bonding solubility parameter δ of less than 9 MPa h and may have. On the other hand, in some other embodiments, the surface modification additive used in the embodiments of the present invention may have a higher polarity than the cellulose ester in the formulated CE material (e.g., during the formulation process) or the CE molten resin (e.g., during the foamed sheet manufacturing process). For example, the surface modification additive may have (based on the Hansen solubility parameter) a total solubility parameter δ of more than 21.5 MPa 1 / 2 more than 23 MPa 1 / 2 more than or 25 MPa 1 / 2The total solubility parameter δ may be greater than or equal to 200°C, 220°C, 240°C, 260°C, 280°C, or 300°C. Furthermore, the surface modification additive may have a molecular weight greater than 100 g / mol, 150 g / mol, 220 g / mol, 260 g / mol, 300 g / mol, or 340 g / mol, and / or less than or equal to 1000 g / mol, less than or equal to 2500 g / mol, or less than or equal to 5000 g / mol. Furthermore, it may be preferable that the surface modification additive is insoluble in the plasticizer(s) used in the cellulose ester composition. For example, it may be preferable that the surface modification additive is insoluble in triacetin. Finally, in some embodiments, the surface modification additive may be biodegradable and / or food-safe or FDA-approved.

[0067] In one embodiment, or in combination with any of the embodiments referenced herein, the surface modifiers are all present in amounts of 0.05 to 0.75% by weight, or 0.05 to 1.0% by weight, or 0.05 to 2.5% by weight, or 0.05 to 5.0% by weight, or 0.75 to 1.0% by weight, or 0.75 to 2.5% by weight, or 0.75 to 5.0% by weight, or 0.1 to 1.0% by weight, or 0.1 to 2.5% by weight, or 0.1 to 5.0% by weight, or 1.0 to 2.5% by weight, or 1.0 to 5.0% by weight, or 2.5 to 5.0% by weight, based on the total weight of the cellulose ester composition. In some embodiments, the surface modifiers used herein may include combinations or mixtures of two or more different types of surface modifiers.

[0068] Goods Extruded sheets of cellulose ester foam can be formed using the extrusion and / or sheet molding sections described above. Such extruded sheets comprise a structural material having a plurality of gas voids arranged throughout. Such gas voids are formed by the expansion of a foaming agent in the form of a gas within a cellulose polymer molten. The structural material is cellulose ester-based, and specific amounts of the constituent components of the structural material (e.g., cellulose ester, plasticizer, nucleating agent, surface modifying additive, etc.) are described in more detail above. Articles can be molded from extruded sheets of foam according to embodiments and may be particularly useful in the food service industry. An exemplary article is a meat tray. This article may have one or more particularly advantageous properties. For example, the article may have selective water absorption, be biodegradable and / or compostable, and / or have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0069] Such cellulose ester foams can be formed from cellulose ester foam sheets by thermoforming, in which heat and optionally pressure are applied to the foam sheet in a mold, producing a three-dimensional article that retains its shape even after being removed from the mold. For example, in some embodiments, the foam sheet is heated to a surface temperature 40-100°C, 50-80°C, or 50-70°C higher than the Tg of the foam sheet. In some embodiments, the Tg of the foam sheet is about 120°C. Therefore, the thermoforming process can heat the foam sheet to a surface temperature of 150-210°C or 160-200°C.

[0070] More specifically, embodiments of the present invention may include a foamed article in the form of a foamed tray, as shown in Figure 6. The foamed tray may be configured as a food tray for supporting one or more food items, such as meat. As shown in the figure, the foamed tray may comprise a substantially flat base and a rim that rises above the base and extends around the foamed tray. The top surface of the base and the surrounding rim define a receiving area (e.g., a bowl) that can hold and support an article (e.g., meat, cheese, vegetables, fruit, or other food items).

[0071] The foam trays molded according to embodiments of the present invention can be molded to various sizes. For example, as shown in Figure 6, the tray may have a width "W" ranging from 2 to 12 inches, 3 to 10 inches, or 5 to 9 inches, and a length "L" of 4 to 24 inches, 5 to 18 inches, or 6 to 15 inches. Thus, in some embodiments, the length of the tray may be 1.2 to 4 times, 1.4 to 3 times, or 1.5 to 2 times the width of the tray.

[0072] The base area can be 5–100 square inches, 10–75 square inches, or 20–50 square inches. The rim height (measured from the bottom of the tray to the top of the rim) can be 0.2–4 inches, 0.4–2 inches, or 0.5–1 inch, and the rim width (i.e., the lateral distance "Rw" measured from the side of the tray to the point where the rim contacts the base, as shown in Figure 6) can be 0.06–0.75 inches, 0.10–0.05 inches, or 0.25–0.50 inches. Alternatively, the rim width "Rw" may be approximately 0.01W–0.1W, or approximately 0.03W–0.06W, where "W" represents the width of the tray, as described above. The ratio of base area to rim area can be 1–10, 1.5–6, or 2–4. Furthermore, the tray depth (measured from the top of the rim to the top of the base) may be 0.3–4 inches, 0.5–3 inches, 1–3 inches, 1–2 inches, 1.25–2 inches, approximately 1.25 inches, or approximately 1.5 inches. Additionally, the thickness of the tray or other article (i.e., the thickness of the cellulose ester foam material) may be 1–10 mm, 1–8 mm, 2–8 mm, 3–7 mm, 4–6 mm, approximately 4 mm, approximately 5 mm, or approximately 6 mm, and / or less than 5 mm, less than 4 mm, less than 3 mm, or less than 2 mm. Alternatively or additionally, the tray or other article may have a thickness of 100–400 mils, 120–300 mils, or 150–250 mils (i.e., the thickness of the cellulose ester foam material).

[0073] Beneficial in this regard, foam trays may possess selective water absorption. For example, when foam trays are used to support meat, it may be preferable that the trays do not absorb liquids released from the meat. Foam trays can be tested for water absorption using the following test procedure (i.e., a "moisture absorption test"). This test procedure includes the following steps: (1) weighing the foam tray to obtain the original tray weight; (2) filling the tray's support with water until the water reaches the top of the rim; (3) allowing the water-filled foam tray to equilibrate at room temperature for one hour or overnight (i.e., 18 hours); (4) removing the water supported in the support to empty the tray; (5) lightly wiping the tray to remove any excess water remaining on the tray surface; (6) weighing the immersed tray to obtain the tray weight after immersion; and (7) calculating the percentage increase in weight of the tray after immersion relative to the original tray weight. As used herein, a "1-hour water absorption test" is defined as the above procedure with equilibration step (3) extended to 1 hour. Also as used herein, an "18-hour water absorption test" is defined as the above procedure with equilibration step (3) extended to 18 hours.

[0074] According to embodiments of the present invention, after filling the tray of the present invention with water and allowing it to equilibrate at room temperature for 1 hour (i.e., under a 1-hour water absorption test), the weight increase of the tray (after removing water from the tray's receiving portion) may be less than 10%, less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, and / or less than 4%. Alternatively, or in addition, after filling the tray of the present invention with water and allowing it to equilibrate overnight at room temperature (i.e., under an 18-hour water absorption test), the weight increase of the tray (after removing water from the tray's receiving portion) may be less than 20%, less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, and / or less than 10.5%.

[0075] After a 1-hour water absorption test and / or an 18-hour water absorption test, the foam tray can be subjected to a further “freeze-thaw test” to test the tray’s ability to absorb water after undergoing a freeze-thaw cycle. The freeze-thaw test includes the following steps: (1) freezing the tray in a freezer overnight (i.e., 18 hours); (2) removing the frozen tray from the freezer; (3) thawing the frozen tray at room temperature overnight (i.e., 18 hours); (4) filling the receiving compartment of the thawed foam tray with water; (5) allowing the water-filled foam tray to equilibrate at room temperature for 12 hours; (6) removing the water supported in the receiving compartment to empty the tray; (7) lightly wiping the empty tray to remove any remaining water from the surface of the tray; (8) weighing the tray after immersion to obtain the tray weight; and (9) calculating the percentage increase in the tray’s weight after immersion relative to its original weight. According to embodiments of the present invention, after the tray undergoes an 18-hour water absorption test and a freeze-thaw test, the weight increase of the tray may be less than 30%, less than 25%, less than 20%, and / or less than 15%.

[0076] To enhance the ability of foam trays to minimize water absorption, a hydrophobic cap layer may be molded onto the outer surface of the foam tray. Such a hydrophobic cap layer can be molded by using hydrophobic additives (e.g., stearic acid, calcium stearate, zinc stearate, glycerol monostearate, etc.) in the material used to mold the cellulose ester foam sheet. For example, the hydrophobic additive may be added to the compounded CE material (e.g., during the compounding process) or to the CE molten resin (e.g., during the foam sheet manufacturing process). Alternatively, or in addition, the hydrophobic cap layer may be molded onto the surface of the foam article by co-extruding, laminating, and / or coating the hydrophobic material onto the foam sheet and / or foam article. As mentioned above, since the foam article may be used to support food such as meat, it may be beneficial to mold the hydrophobic cap layer onto the top surface of the food-supporting foam article (e.g., the surface of the foam article and / or tray forming a bowl or receiving section).

[0077] Several sample trays were molded and tested using water absorption and freeze-thaw tests. The trays were molded from cellulose ester foam sheets extruded using a tandem extruder system. The extruded cellulose ester molten resin contained cellulose diacetate with a degree of substitution of 2.52, a melting point of 230-250°C, and a Tg of 189°C. The molten resin was plasticized by adding 15-20% by weight of triacetin. Talc was used as a nucleating agent and mixed with a physical blowing agent into the molten resin in the twin-screw extruder of the tandem extruder system. The resulting molten resin was transferred to a single-screw extruder, and the cellulose ester foam sheet was extruded using an annular die in the single-screw extruder. The foam sheet was stretched, cut, and thermoformed to form foam trays. The results of four samples subjected to a 1-hour water absorption test are shown in Table 1. The results of four samples subjected to an 18-hour water absorption test are shown in Table 2. The results of two samples subjected to a freeze-thaw test are shown in Table 3. Please note that each sample used at least three foam trays, and the measurements were averaged to obtain the results shown below. [Table 1] [Table 2] [Table 3] Embodiments provide the above-described foam trays formed according to the process described herein. Specifically, a mixed composition containing cellulose ester can be extruded through an extruder to form a cellulose ester foam sheet. The foam sheet can then be thermoformed to form a tray, which may include a generally planar base and a rim extending upward from the base along the perimeter of the tray. The resulting foam tray can be used to support food such as meat. In some embodiments, an absorbent pad is placed on top of the base within the tray's receiving section so that liquids from the meat (or other food) can be absorbed by the pad. Furthermore, a shrink film or overlap film can be wrapped around the tray to securely hold the meat inside and protect it from the environment. Beneficially, the trays described herein can be formed at a selective density, which makes it possible to form the tray on an economically efficient basis. Such a selective density can be achieved by post-foaming of the foam produced in the cellulose ester material used for the tray.

[0078] More specifically, according to embodiments of the present invention, a foamed sheet can be produced from a cellulose ester composition, for example, by extrusion. The resulting foamed sheet may have an extruded sheet density. The foamed sheet may then be thermoformed to form a foamed article, such as a food tray or meat tray. The resulting article may undergo post-thermoform foaming, resulting in a density of at least 20%, at least 30%, at least 40%, and / or at least 50% lower than the sheet density of the initial foamed sheet. Furthermore, as a result of post-foaming, the resulting article may have a density of 0.095 g / cm³. 3 Below, 0.09g / cm 3 Below, 0.08g / cm 3 Below, 0.07g / cm 3 Below, 0.06g / cm 3 Below 0.05g / cm 3 The following and / or 0.04 g / cm³ 3The following densities are possible. Beneficially, cellulose ester-based thermoformed articles can achieve such post-foaming without a large amount of foaming agent remaining in the thermoformed article (or in the preceding foamed sheet). In particular, it has been confirmed that most of the foaming agent used during extrusion to form cellulose ester-based foamed sheets diffuses and / or leaks out from the foamed sheet immediately after extrusion. For example, in some embodiments, the foamed article has less than 1% by weight, less than 0.5% by weight, and / or less than 0.1% by weight of physical foaming agent within 24 hours, 12 hours, 6 hours, 2 hours, 1 hour, 30 minutes, 10 minutes, and / or 1 minute after thermoforming.

[0079] Abbreviation BA is a foaming agent, tPent is t-pentane, IsoPent is isopentane, nPent is n-pentane, CycloPent is cyclopentane, IsoBut is isobutane, Styr is styrene, PolyStyr is polystyrene, and TA is triacetin.

[0080] For example, several sample trays were molded and tested for density changes and foaming agent content after thermoforming. The trays were molded from cellulose ester foam sheets extruded using a tandem extruder system. The extruded cellulose ester molten resin contained cellulose diacetate with a degree of substitution of 2.52, a melting point of 230-250°C, and a Tg of 189°C. The molten resin was plasticized by adding 15% or 20% by weight of triacetin. Talc was used as a nucleating agent and mixed with a physical foaming agent into the molten resin in the twin-screw extruder of the tandem extruder system. The resulting molten resin was transferred to a single-screw extruder, and the cellulose ester foam sheet was extruded using an annular die in the single-screw extruder. The foam sheet was stretched, cut, and thermoformed to form foam trays. Counterexample foam trays containing polystyrene were molded similarly.

[0081] The density of the sample trays was tested before and after thermoforming by immersing the sample in water and measuring the volume using a chemical balance based on Archimedes' principle. This method is described in DIN EN ISO 1183-1 and ISO 2781. A minimum of three samples were measured, with each sample weighing between 1 and 5 gm. The results of the sample density measurements are shown in Table 4 below. The polystyrene counterexample tray showed the highest post-foaming, while the cellulose ester-based tray was able to achieve 60-80% of the polystyrene post-foaming. [Table 4] Furthermore, residual foaming agent remaining in the sample tray after thermoforming was measured using liquid chromatography-mass spectrometry (LC / MS). Gases leaking during thermoforming were captured using headspace gas chromatography by heating the sample to 200°C. For quantification of volatile substances, the sample was dissolved in a solvent and its components were measured using LC / MS. The foaming agent used in all samples was hydrocarbon. As shown in Table 5, the amount of hydrocarbon foaming agent soluble in cellulose ester-based trays was found to be significantly less than in polystyrene trays. This decrease in foaming agent is likely due to the fact that the solubility parameters of hydrocarbon gases are similar to those of polystyrene, and therefore they are more soluble in polystyrene than cellulose esters. As a result, it is thought that foamed sheets formed from polystyrene need to be processed in stages after extrusion (and before thermoforming) and stored for longer periods to allow sufficient diffusion of the foaming agent from the sheet. In contrast, cellulose ester-based foamed sheets can be thermoformed more quickly because most of the foaming agent diffuses immediately after the foamed sheet is extruded. Furthermore, since the blowing agent is not retained by the cellulose ester-based foam sheet and / or article, the range of commercially suitable blowing agents that can be used to extrude the cellulose ester-based foam sheet is broadened. [Table 5] Some of the above advantages of cellulose ester-based foam articles can be achieved by the change in cell shape that occurs after thermoforming. While the foam sheet is extruded using an annular die, the sheet is stretched on the mandrel, resulting in the sheet being stretched and the cells elongated. As the foam sheet cools, the cells generally freeze in place in an elongated shape. When the cells of a cellulose ester-based foam article are exposed to heat during thermoforming, they effectively expand and return to a more rounded shape. Figure 7A is a scanning electron microscope (SEM) image of a cross-section of a cellulose ester-based foam sheet before thermoforming. Figure 7B is an SEM image of a cellulose ester-based foam sheet after thermoforming. As shown, the shape of the cells in the cellulose ester-based foam sheet becomes more rounded and the aspect ratio (i.e., width:height) becomes smaller after thermoforming. Thus, in some embodiments, a foam article containing cellulose ester is provided, which contains multiple cells. Embodiments provide that at least 50% of the multiple cells have a cross-sectional aspect ratio of 1:2 to 2:1. In other embodiments, at least 50% of the cells may have cross-sectional aspect ratios of 1:1.8 to 1.8:1, 1:1.6 to 1.6:1, 1:1.4 to 1.4:1, and / or 1:1.2 to 1.2:1.

[0082] In one embodiment, or in combination with any of the embodiments referred to herein, the foamed article, for example, the tray, is 0.20 g / cm³. 3 Less than 0.18 g / cm³ 3 Less than 0.15 g / cm³ 3 Less than 0.12 g / cm³ 3 Less than 0.10 g / cm³ 3 Less than 0.08 g / cm³ 3 Less than 0.06 g / cm³ 3 Less than 0.04 g / cm³ 3 Less than 0.04-0.8 g / cm³ 3 , 0.04~0.6 g / cm³ 3 , 0.04~0.5 g / cm³ 3 , 0.04~0.4 g / cm³ 3 , 0.04~0.3 g / cm³ 3 , 0.04~0.2 g / cm³3 、0.04~0.15g / cm 3 、0.04~0.12g / cm 3 、0.04~0.10g / cm 3 、0.04~0.08g / cm 3 、0.04~0.06g / cm 3 、0.06~0.8g / cm 3 、0.06~0.6g / cm 3 、0.06~0.5g / cm 3 、0.06~0.4g / cm 3 、0.06~0.3g / cm 3 、0.06~0.2g / cm 3 、0.06~0.15g / cm 3 、0.06~0.12g / cm 3 、0.06~0.10g / cm 3 、0.06~0.08g / cm 3 、0.08~0.8g / cm 3 、0.08~0.6g / cm 3 、0.08~0.5g / cm 3 、0.08~0.4g / cm 3 、0.08~0.3g / cm 3 、0.08~0.2g / cm 3 、0.08~0.15g / cm 3 、0.08~0.12g / cm 3 、0.08~0.10g / cm 3 、0.1~0.8g / cm 3 、0.1~0.6g / cm 3 、0.1~0.5g / cm 3 、0.1~0.4g / cm 3 、0.1~0.3g / cm 3 、0.1~0.2g / cm 3 、0.1~0.15g / cm 3 、0.1~0.12g / cm 3 、0.2~0.8g / cm 3 、0.2~0.6g / cm 3 、0.2~0.5g / cm 3 、0.2~0.4g / cm 3 、0.2~0.3g / cm 3 、0.3~0.6g / cm 3, 0.3~0.5 g / cm 3 , 0.3~0.4 g / cm³ 3 , 0.4~0.6 g / cm³ 3 , 0.4~0.5 g / cm 3 , or 0.5~0.6 g / cm³ 3 It may have a density of .

[0083] In one embodiment, or in combination with any of the embodiments referred to herein, the average foam cell size is 40 μm to 600 μm, or 50 μm to 600 μm, or 60 μm to 600 μm, or 70 μm to 600 μm, or 80 μm to 600 μm, or 90 μm to 600 μm, or 100 μm to 600 μm, or 150 μm to 600 μm, or 200 μm to 600 μm, or 250 μm to 600 μm. m, or 300μm~600μm, or 400μm~600μm, or 500μm~600μm, or 40μm~550μm, or 40μm~500μm, or 40μm~450μm, or 40μm~400μm, or 40μm~350μm, or 40μm~300μm, or 40μm~250μm, or 40μm~200μm, or 40μm~150μm, or 40μm~100μm.

[0084] Furthermore, since foamed articles, such as trays, are molded from the cellulose esters described herein, it should be understood that foamed articles may contain any components and / or additives of the cellulose ester-based materials described herein, as well as any resulting properties.

[0085] definition It should be understood that the following is not intended to be an exclusive list of the terms to be defined. Other definitions, for example, when used in context, may be provided in the explanations above.

[0086] As used herein, the terms "a," "an," and "the" mean one or more.

[0087] As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transitional clauses used to move the subject listed before the term to one or more elements listed after the term, the elements listed after the transitional clause are not necessarily the only elements that constitute the subject.

[0088] To be considered "compostable," materials must meet one or more of the following criteria: (1) the materials must be biodegradable; (2) the materials must be disintegrable; (3) the materials must not contain heavy metals in amounts exceeding the maximum; and / or (4) the materials must not be ecotoxic.

[0089] As used herein, the term “biodegradability” generally refers to the biological transformation and consumption of organic molecules. Biodegradability is an inherent property of the material itself, and materials may exhibit different degrees of biodegradability depending on the specific conditions to which they are exposed. The term “disintegrability” refers to the tendency of a material to physically decompose into smaller fragments when exposed to specific conditions. Disintegration depends on both the material itself and the physical size and composition of the article being tested. Ecotoxicity measures the effect of a material on plants, and the heavy metal content of a material is determined according to the procedures presented in standard test methods.

[0090] To be considered "compostable at home" under home composting conditions according to the French standard NF T 51-800, the material must show at least 90 percent disintegration in total (e.g., compared to an initial sample) within 12 weeks, as measured according to ISO 16929 (2013) at ambient temperature (i.e., 28°C ± 2°C).

[0091] To be considered "industrially compostable" under industrial composting conditions according to ASTM D6400, the material must show at least 90 percent disintegration in total (e.g., compared to an initial sample) within 26 weeks, as measured according to ISO 16929 (2013) at high temperatures (i.e., 58°C ± 2°C).

[0092] In one embodiment, or in combination with any of the embodiments referred to herein, a biodegradable cellulose ester foam or article (e.g., a tray) is industrially compostable and / or compostable at home. Specifically, the foam material that forms the basis of the articles described herein is industrially compostable according to ASTM D6400 and can exhibit at least 90 percent decomposition within 12 weeks, as measured according to ISO 16929 (2013) at a high temperature of 58°C ± 2°C. Furthermore, or alternatively, the foam material that forms the basis of the articles described herein is compostable at home according to the French standard NF T 51-800 and can exhibit at least 90 percent decomposition within 26 weeks, as measured according to ISO 16929 (2013) at an ambient temperature of 28°C ± 2°C.

[0093] In some specific embodiments, the foam material has a thickness of 200 mils or less (or a thickness equal to this thickness) and a density of 0.2 g / cm². 3 A foamed article may be industrially compostable if it is formed with the following density (or a density equal to this density): Alternatively or additionally, the foamed material may have a thickness of 400 mils or less (or a thickness equal to this thickness) and a density of 0.1 g / cm³. 3 A foamed article may be industrially compostable if it is formed with the following density (or a density equal to this density): Alternatively or additionally, the foamed material may have a thickness of 800 mils or less (or a thickness equal to this thickness) and a density of 0.05 g / cm³. 3 A foamed article may be industrially compostable if it is formed to have the following density (or a density equal to this density): Alternatively, or additionally, the foaming material may be 0.2 g / cm³. 3If formed into a foamed article having a density (or equal to) below the following density and a thickness (or equal to) of 100 mils or less, it may be compostable at home. Alternatively or additionally, the foaming material may be 0.1 g / cm³. 3 If formed into a foamed article having a density (or equal density) below the following and a thickness (or equal thickness) of 200 mils or less, it may be compostable at home. Alternatively or additionally, the foaming material may be 0.05 g / cm³. 3 It may be possible to compost it at home if it is formed into a foamed article having a density (or a density equal to this density) and a thickness (or a thickness equal to this thickness) of 400 mils or less.

[0094] The compositions used to produce biodegradable cellulose acetate foam may include other additives such as fillers, stabilizers, odor modifiers, waxes, compatibilizers, biodegradation accelerators, dyes, pigments, colorants, lubricants, antioxidants, viscosity modifiers, antifungal agents, heat stabilizers, antimicrobial agents, softeners, release agents, UV absorbers, hydrophobic additives, and combinations thereof. Each additional additive may be present in the cellulose ester material in amounts of less than 10% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, or less than 1.0% by weight. It should be noted that for multiple categories of components in the cellulose acetate composition, the same type of compound or material may be specified or included. For example, polyethylene glycol (PEG) may function as a plasticizer or as an additive that does not function as a plasticizer, such as a hydrophilic polymer or biodegradation accelerator. For example, low molecular weight PEG has a plasticizing effect, while high molecular weight PEG functions as a hydrophilic polymer but does not have a plasticizing effect.

[0095] In one embodiment, or in combination with any other embodiment referred to herein, the foam, composition, or foaming composition further comprises a photocatalyst. In one class of this embodiment, the photocatalyst is titanium dioxide or iron oxide. In one subclass of this class, the photocatalyst is titanium dioxide. In one subclass of this class, the photocatalyst is iron oxide.

[0096] In one embodiment, or in combination with any other embodiments referenced herein, the foam, composition, or foaming composition further comprises a pigment. In one class of this embodiment, the pigment is titanium dioxide, carbon black, or iron oxide. In one subclass of this class, the pigment is titanium dioxide. In one subclass of this class, the pigment is carbon black. In one subclass of this class, the pigment is iron oxide. In one subclass of this class, the pigment is a biodegradable particulate natural filler.

[0097] Abbreviation Wt stands for weight, wt% for weight percentage, IR for infrared, and Ex for example(s).

[0098] Manufacturing and thermoforming of films and foam sheets A 1-foot wide film was extruded to the following desired thicknesses using a 1.5-inch Kilion extruder. Extrusion conditions were controlled by a take-off assembly and set based on polymers including PETG, Eastman cellulose acetate FT1150, and Eastman cellulose acetate FT1200, extruded at 220-240°C through a coat hanger type die to the desired thickness.

[0099] The foamed sheet samples were produced on a tandem foaming line made by Kraus Maffei. The extrusion line consists of a ZE30 twin-screw extruder as the primary extruder and a KE60 single-screw extruder as the secondary cooling extruder to which the ZE30 is connected. A loss-in-weight and gravimetric feeder are used to feed the compounding additives into the KE30 twin-screw feeder. The physical blowing agent is injected into the primary extruder downward from about 1 / 2 to 2 / 3 in the barrel of the primary extruder. The material is extruded from a 50-mm annular die and conveyed over a sizing mandrel. Next, the annular film is cut and changed into a flat film at the roll tension / winding station part.

[0100] The material composition is a cellulose acetate resin (e.g., Eastman cellulose acetate CA-398-30 or FE700) having 20 wt% triacetin, 1% epoxidized soybean oil, and 0.15% doverphos S9228T, as well as other trace stabilizers / odor masks. 2.6 wt% n-pentane is injected into the material as a blowing agent. The additional additives to the process include 1.5 wt% ABT 1000 talc and 1% chemical blowing agent (foamazol 73S). The material was extruded at 200 - 220 °C in the primary extruder and at 170 - 190 °C in the secondary extruder. The production rate of the line was 40 kg / h. The density of the foam produced for this test was 0.95 g / cc, and the average cell size was 342 microns.

[0101] The film was placed on the upper side of the foam and clamped to the frame of the Hydrotrim Lab thermoforming machine. This unit includes upper and lower heating mounting plates in the oven, a timer for setting the holding time in the oven, a vacuum for drawing the material into the mold, and a plug assist for use with complex parts. The materials evaluated for this study were produced using only vacuum, and the upper and lower mounting plates were heated to 260 °C. The sheet temperature when the parts were heated for 34 seconds was measured to be 190 - 205 °C by an infrared thermometer.

[0102] The moisture absorption test was conducted as described above.

[0103] A solid skin layer can be created in any process, such as by controlling the evaporation rate of the foaming agent during the foaming process to solidify a thick skin, or by adding layers to the foam during manufacturing by co-extrusion. By placing this layer on one side, A / B (film / foam) structures or ABA (film / foam / film) structures can be created. Furthermore, the foam can be laminated in a secondary roll-to-roll process to produce the same structure, or it can be similarly produced during the thermoforming process. Foamed parts can be manufactured in a vacuum alone, or preferably using plug assist or matched mold sets to ensure the best part distribution, etc. The film layer can be a very thin layer, 0.0001 to 0.05 inches (0.0025 to 1.27 mm) thick. [Table 6]

[0104] Table 7 shows the ambient temperature and high-temperature collapse of foams in accordance with ISO 20200 and ISO 16929. [Table 7] Foamed sheet samples were prepared using a Kraus Maffei tandem foaming line. The extrusion line consists of a ZE30 twin-screw extruder as the primary extruder and a KE60 single-screw extruder as the secondary cooling extruder to which the ZE30 is coupled. Compounding additives are fed into the KE30 twin-screw feeder using weight-reducing and gravimetric feeders. Physical foaming agent is added from approximately half the barrel of the primary extruder. 2 / The material is injected downwards into the primary extruder up to 3. The material is extruded from a 50 mm annular die and transported on a sizing mandrel. The annular film is then cut and converted into a flat film at the tension / winding station section of the roll.

[0105] The composition of Material 1 is a cellulose acetate resin (Eastman cellulose acetate CA-398-30 or Eastman cellulose acetate FE700) containing 20 wt% triacetin, 1% epoxidized soybean oil, and 0.15 wt% doverphos S9228T, as well as other trace stabilizers / odor masks. 2.6 wt% n-pentane is injected into the material as a blowing agent. Additional additives to the process include 1.5 wt% ABT 1000 talc and 1 wt% chemical blowing agent (foamazol 73S). The material was extruded in a primary extruder at 200-220°C and in a secondary extruder at 170-190°C. The line production rate was 40 kg / hour.

[0106] The composition of material 2 is a cellulose acetate resin (Eastman cellulose acetate CA-398-30 or Eastman cellulose acetate FE700) containing 15 wt% triacetin, 1 wt% epoxidized soybean oil, and 0.15 wt% Doverphos S9228T, as well as other trace stabilizers / odor masks. 2.5 wt% n-pentane is injected into the material as a blowing agent. Additional additives to the process include 1.0 wt% ABT 1000 talc and 1 wt% chemical blowing agent (Foamazol 73S). The material was extruded in a primary extruder at 200-220°C and in a secondary extruder at 180-200°C. The line production rate was 40 kg / hour.

[0107] The composition of material 3 is a cellulose acetate resin (Eastman cellulose acetate CA-398-30 or Eastman cellulose acetate FE700) containing 15 wt% triacetin, 1 wt% epoxidized soybean oil, and 0.15 wt% Doverphos S9228T, as well as other trace stabilizers / odor masks. 2.3 wt% n-pentane is injected into the material as a blowing agent. Additional additives to the process include 1.0 wt% ABT 1000 talc and 1 wt% chemical blowing agent (Foamazol 73S). The material was extruded in a primary extruder at 200-220°C and in a secondary extruder at 170-190°C. The line production rate was 40 kg / hour.

[0108] The material was thermoformed using a Hydrotrim Lab thermoforming machine. This unit features upper and lower heating plates inside the oven, a timer for setting the holding time inside the oven, a vacuum for drawing the material into the mold, and a plug assist for use with complex parts. The material evaluated for this study was fabricated using vacuum only, with the upper and lower mounting plates heated to 260°C. The sheet temperature was measured from 157 to 197°C using an infrared thermometer. [Table 8] [Table 9] The composition of material 4 is a cellulose acetate resin (Eastman cellulose acetate CA-398-30 or Eastman cellulose acetate FE700) containing 20 wt% triacetin, 1 wt% epoxidized soybean oil, 0.15 wt% Doverphos S9228T, and 1 wt% zinc stearate. 2.6 wt% n-pentane is injected into the material as a blowing agent. Additional additives to the process include 1 wt% ABT 1000 talc and 1 wt% chemical blowing agent (Foamazol 73S). The material was extruded in a primary extruder at 200-220°C and in a secondary extruder at 170-190°C. The line production rate was 40 kg / hour.

[0109] Materials (e.g., materials 1, 2, and 4) were thermoformed using a Hydrotrim Lab thermoforming machine. This unit includes upper and lower heating plates within the oven, a timer for setting the holding time in the oven, a vacuum for drawing the material into the mold, and a plug assist for use with complex parts. The materials evaluated for this study were fabricated using vacuum only, with the upper and lower mounting plates heated to 260°C. Sheet temperatures were measured between 180 and 197°C using an infrared thermometer. [Table 10] [Table 11]

[0110] Method Overview Sheets of foamed cellulose acetate (Eastman cellulose acetate CA-398-30 or Eastman cellulose acetate FE700) were allowed to set in a desiccator for 7 days, with the desiccant replaced with a small pan containing pentane to maintain a saturated atmosphere. Three 4cm x 5cm subsamples were cut from the large sheet sample. These subsamples were placed in individual resealable 5 x 7cm polyethylene bags and quickly returned to the desiccator. The bags were left open to facilitate the re-establishment of pentane saturation. After 3 hours, the bags containing the foam were removed from the desiccator, and the samples were tested individually by immediately sealing the bags and recording their weight. Next, the foam pieces were removed from the bags and placed in a small oven at 186±1.0℃ for 45 seconds. After the heating period, the samples were removed from the oven, immediately sealed in their original bags, and weighed again.

[0111] Experimental apparatus The oven used was a Pierce Reacti-Therm III heating / stirring module, which utilized an aluminum heat block with a large hole approximately 4.5 cm in diameter and 5 cm deep, and an open top. This hole was used as the heating chamber. To increase the heat mass, additional aluminum heat blocks were added to both sides of the heating chamber, and a stainless steel plate approximately 3 inches x 6 inches x 3 / 4 inches thick was placed on top to seal the mini-chamber while heating the sample. The temperature inside the heating chamber was monitored using an Amprobe TMD-56 digital thermometer and thermocouple installed in a thermal well in the heat block. Samples were weighed using a Mettler Toledo XPE56 6-position microbalance, and time was measured with a digital lab timer. Throughout the experiment, the entire oven apparatus was placed in a fume hood.

[0112] The above method was used to simulate thermoforming and accurately measure the maximum foaming agent retention rate of cellulose acetate under thermoforming conditions. The oven temperature in thermoforming is typically 250–350°C. The oven can be set to a constant temperature or to gradually rise as the sheet moves across the oven. The sheet temperature is 180–200°C before molding to ensure that the sheet stretches sufficiently within the mold. The foaming agent used in the production of the foam is typically about 2.3–3.5% hydrocarbons during extrusion molding, and usually more than half is lost as the foam cools during the extrusion molding process. [Table 12]

[0113] Claims not limited to the disclosed embodiments The preferred embodiments of the present invention described above are for illustrative purposes only and should not be used to limit the meaning of the interpretation of the scope of the invention. Modifications to the exemplary embodiments described above can be readily made by those skilled in the art without departing from the spirit of the invention.

[0114] The inventors hereby express their intention to determine and evaluate the reasonably fair scope of the invention on the basis of the doctrine of equivalents whenever the invention relates to any device that does not substantially deviate from, but falls outside, the literal scope of the invention as set forth in the following claims.

Claims

1. A foam tray comprising a cellulose ester and a hydrophobic cap layer molded on the outer surface of the foam tray, The tray is a foam tray configured such that, as described herein, it exhibits a weight increase of less than 10% when subjected to a one-hour water absorption test.

2. The foam tray according to claim 1, wherein the hydrophobic cap layer is molded onto the outer surface of the foam tray.

3. The foam tray according to claim 1 or 2, wherein the hydrophobic cap layer is molded onto the upper surface of the tray.

4. The foam tray according to any one of claims 1 to 3, wherein the hydrophobic cap layer is molded onto the surface of the tray that forms a bowl or receiving portion configured to support food.

5. The foam tray according to any one of claims 1 to 4, wherein the foam tray is formed from a foam sheet, and the foam sheet includes a hydrophobic cap layer formed on the outer surface of the foam sheet by a co-extrusion process, a lamination process, or a coating process.

6. The foam tray according to any one of claims 1 to 5, wherein the foam tray is configured to support food.

7. The foam tray according to any one of claims 1 to 6, wherein the food is one or more of the following: animal protein or plant protein, vegetables, or fruits.

8. The foam tray is the foam tray according to any one of claims 1 to 7, wherein the foam tray includes an absorbent pad.

9. The foam tray according to any one of claims 1 to 8, wherein the foam tray is configured to be wrapped in shrink film or overlap film.

10. The foam tray according to any one of claims 1 to 9, wherein the foam tray has a width in the range of 2 to 14 inches, 3 to 10 inches, or 5 to 9 inches, and a length of 4 to 24 inches, 5 to 18 inches, or 6 to 15 inches.

11. The foam tray according to any one of claims 1 to 10, wherein the foam tray has a length of 1.2 to 4 times, 1.4 to 3 times, or 1.5 to 2 times the width of the tray.

12. The foam tray according to any one of claims 1 to 11, wherein the foam tray has a depth of 0.3 to 4 inches, 0.5 to 3 inches, 1 to 3 inches, 1 to 2 inches, 1.25 to 2 inches, about 1.25 inches, or about 1.5 inches.

13. The foam tray according to any one of claims 1 to 12, wherein the thickness of the foam tray is 1 to 10 mm, 1 to 8 mm, 2 to 8 mm, 3 to 7 mm, 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.

14. The foam tray according to any one of claims 1 to 13, wherein when the foam tray is filled with water and allowed to equilibrate at room temperature for 18 hours, the foam tray exhibits a weight increase of less than 15% according to the water absorption test described herein.

15. The foam tray is industrially compostable according to ASTM D6400, thereby exhibiting at least 70 percent, or at least 80 percent, or at least 90 percent, disintegration within 12 weeks as measured according to ISO 16929 (2013) at a high temperature of 58°C ± 2°C. The foam tray according to any one of claims 1 to 14, wherein the foam tray is compostable at home in accordance with the French standard NFT 51-800, thereby exhibiting at least 70 percent, or at least 80 percent, or at least 90 percent disintegration within 26 weeks as measured in accordance with ISO 16929 (2013) at an ambient temperature of 28°C ± 2°C.

16. A method for molding foamed articles, (a) Producing a foamed sheet from a composition containing cellulose ester and having a certain sheet density, (b) Thermoforming the foam sheet to form a foamed article having a certain density, wherein the density of the article is at least 20% less than the density of the sheet. The method, including the method described above.

17. The method according to claim 16, wherein the density of the article is at least 25% or at least 30% lower than the density of the sheet, or the density of the article is 20 to 30% or 25 to 30% lower than the density of the sheet.

18. The density of the aforementioned article is 0.095 g / cm³. ３ Below, 0.09g / cm ３ Below, 0.08g / cm ３ Below, 0.07g / cm ３ Below, 0.06g / cm ３ Below, 0.05g / cm ３ The following and / or 0.04 g / cm³ ３ The method according to any one of claims 16 to 17, which is as follows:

19. The method according to any one of claims 16 to 18, wherein the foamed article is a foamed tray configured to support food.

20. The method according to any one of claims 16 to 19, wherein the composition comprises a cellulose ester, a plasticizer, a nucleating agent, and a physical blowing agent.

21. The method according to claim 20, wherein the composition comprises 2 to 40% by weight, or 10 to 30% by weight, or 15 to 20% by weight of a plasticizer.

22. The method according to claim 21, wherein the plasticizer comprises triacetin.

23. The method according to any one of claims 16 to 22, wherein the foamed article comprises one or more additional additives.

24. The method according to claim 23, wherein the additional additive is present in an amount of less than 10% by weight, or less than 5% by weight, or less than 4% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1.0% by weight.

25. The method according to any one of claims 16 to 24, wherein the foamed article contains less than 1% by weight of the physical foaming agent 24 hours after the thermoforming.

26. The method according to claim 25, wherein the foamed article contains less than 0.5% by weight or less than 0.1% by weight of the physical foaming agent 12 hours, 6 hours, 2 hours, 1 hour, 30 minutes, 10 minutes, or 1 minute after the thermoforming.

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