Cellulose ester foam article

Abstract

A tray comprising a cellulose ester. The tray is configured to experience a weight increase of less than 10% when subjected to a one-hour water absorption test as described in the specification.

Description

Background Art

[0001] Many foam products (such as food packaging products) are disposable items that are intended to be disposed of after use. A commercially important material for making foam products is polystyrene. However, polystyrene is neither compostable nor biodegradable. In addition, some cities, states, and countries have enacted or are considering enacting bans on the use of polystyrene-based foams. Therefore, it is desirable to find alternative materials for foam products and feasible compositions, methods, and systems for producing such products. Summary of the Invention

[0002] In one embodiment or in combination with any other embodiment mentioned herein, there is provided a pallet comprising a cellulose ester. The pallet is configured to experience a weight gain of less than 10% when subjected to a one-hour water absorption test as described in the specification.

[0003] In another embodiment or in combination with any other embodiment mentioned herein, there is provided a foam article formed from a foam material comprising a cellulose ester and at least one plasticizer. The foam material is industrially compostable according to ASTM D6400, exhibiting at least 90% disintegration within twelve weeks as measured according to ISO 16929 (2013) at an elevated temperature of 58°C ± 2°C. The foam material is home compostable according to French standard NF T 51-800, exhibiting at least 90% disintegration within twenty-six weeks as 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 mentioned herein, a thermoformed foam article is provided, comprising a cellulose ester and a plurality of cells formed therein, at least 50% of the plurality of cells having a cross-sectional aspect ratio of 1:2 to 2:1.

[0005] In another embodiment or in combination with any other embodiment mentioned herein, a method of forming a foam article is provided. The method includes the step of producing a foam sheet from a composition comprising a cellulose ester. An additional step includes thermoforming the foam sheet to form a foam article having an article density. The article density does not exceed 0.095 g / cm 3 .

[0006] In another embodiment or in combination with any other embodiment mentioned herein, a method of forming a foam article is provided. The method includes the step of producing a foam sheet from a composition comprising a cellulose ester and having a sheet density. An additional step includes thermoforming the foam sheet to form a foam article having an article density. The article density is at least 20% less than the sheet density.

[0007] In another embodiment or in combination with any other embodiment mentioned herein, a method of forming a foam article is provided. The method comprises producing a foam sheet from a composition comprising a cellulose ester and a physical blowing agent. An additional step comprises thermoforming the foam sheet to form a foam article having less than 1 wt.% of the physical blowing agent twenty-four hours after thermoforming. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram illustrating a process for forming a biodegradable article according to an embodiment of the present invention;

[0009] Figure 2 is a schematic diagram illustrating another process for forming a biodegradable article according to an embodiment of the present invention;

[0010] Figure 3 This is a diagram illustrating a method for use in accordance with an embodiment of the present invention. Figure 1 and / or Figure 2 Schematic diagram of the extrusion section in the product forming process;

[0011] Figure 4 This is a diagram illustrating a method for use in accordance with an embodiment of the present invention. Figure 1 and Figure 2 A schematic diagram of another extrusion section in the product forming process;

[0012] Figure 5 This is a diagram illustrating a method for use in accordance with an embodiment of the present invention. Figure 1 and / or Figure 2 A schematic diagram of a sheet forming section in a product forming process;

[0013] Figure 6 is a top plan view of a foam article in the form of a food tray according to an embodiment of the present invention.

[0014] Figure 7A is a scanning electron microscope image of a cross-section of a cellulose ester-based foam sheet prior to thermoforming; and

[0015] Figure 7B is a scanning electron microscope image of a cross section of a cellulose ester-based foam sheet after thermoforming. DETAILED DESCRIPTION

[0016] Embodiments generally relate to methods, systems, and compositions for forming biodegradable particulate materials (e.g., pellets), foam sheets, and articles. Exemplary methods including the methods, systems, and compositions are depicted in Figure 1-Figure 5 and described in more detail below.

[0017] Methods and systems

[0018] like Figure 1 and Figure 2 As shown, raw materials can be introduced into a biodegradable polymer production process, and the process produces a biodegradable polymer material. In one embodiment or in combination with any other embodiment mentioned herein, the biodegradable polymer material comprises one or more cellulose esters. The one or more cellulose esters can include cellulose acetate. In such embodiments, the raw materials can include pulp, such as wood pulp and / or cotton pulp. The pulp can be a dissolving grade pulp and / or a paper grade pulp. The cellulose in the pulp can be esterified, for example, with acetic acid to form a biodegradable cellulose ester polymer, such as a cellulose acetate polymer.

[0019] The biodegradable polymer material can then be introduced into a compounding process, wherein the biodegradable polymer material can be mixed with a plasticizer and optionally one or more other additives (e.g., stabilizers) and a compounded material comprising the plasticized biodegradable polymer is formed. Other additives can also be mixed with the polymer and plasticizer. For example, Figure 2 As shown, other materials (additives) may include, but are not limited to, stabilizers, one or more physical blowing agents, one or more chemical blowing agents (and / or precursors), one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers, and / or one or more other additives. Mixing can be accomplished by any known mixing technique, including but not limited to rolling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling.

[0020] The compounding process may include a microgranulation process. The microgranulation process may generally include mixing a biodegradable polymer material, a plasticizer, and one or more other additives to form a mixed composition, and forming a microgranulate material from the composition. In particular, the microgranulation process may include a granulation process, and the microgranulate material may include a certain amount of granules. The term "compounded CE material" means a cellulose ester material formed during the compounding process, which may include a mixture of cellulose ester, plasticizer, and other additives. In addition, such compounded CE material may be in the form of microgranulate material or granules. It should be understood that, as used herein, the phrase "microgranulation" or "microgranulation process" may be the same as "granulation" or "granulation process" or may at least include "granulation" or "granulation process". In some embodiments, the microgranulation process may include granulation into a water bath, granulation on an air cooling belt, underwater granulation, solvent compounding, etc.

[0021] In one embodiment or in combination with any other embodiment mentioned herein, the plasticizer and one or more other additives can be mixed with the cellulose ester by conventional melt compounding techniques, which involve combining the cellulose ester with the plasticizer and, optionally, other additives, at appropriate temperature and pressure in a twin-screw extruder with appropriate mixing elements to obtain a molten, uniformly combined cellulose ester mixture when the material leaves the extruder. The molten compounded cellulose ester mixture can then be extruded through a die having an orifice having a diameter of about 2-6 mm to extrude a strand. This strand can then be cooled by water (e.g., by underwater pelletizing) or air and cut at regular intervals to provide a uniform and desired size and shape, referred to as "pellets" or "particulates." Although methods for forming granulated compounded materials are described herein, it will be understood that, according to some embodiments, the compounded material fed to the foam sheet production process can be in any physical form (e.g., pellets, powders, particulates, fibers). The term "compounded CE material" means the cellulose ester material formed during the compounding process, which can include a mixture of cellulose ester, plasticizer, and other additives. Furthermore, such compounded CE materials may be in the form of a melt mixture or a particulate material (eg, pellets, powder, granules, fibers, etc.).

[0022] The compounded CE material, which may comprise pellets of plasticized biodegradable polymer as described above, may then be introduced into the foam sheet production process, e.g. Figure 1 and Figure 2 As shown. The foam sheet production method may include one or more areas / steps for producing a foam sheet or film, which are described in more detail below. Although exemplary foam sheet production methods are described herein, it should be understood that certain aspects described herein may also be applicable to rigid (i.e., non-foam) materials and articles. Figure 1As shown, in one embodiment or in combination with any other embodiment mentioned herein, various additives can be introduced into one or more zones of the foam sheet production process. The additives can include, but are not limited to, stabilizers, one or more physical blowing agents, one or more chemical blowing agents (and / or precursors), one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0023] The foam sheet production process may generally include an extrusion stage and a sheet forming stage. Figure 3 An exemplary extrusion section is depicted. As shown, the extrusion section may include a feed preparation zone, wherein solid additives may be combined with the compounded CE materials and introduced into the downstream extrusion zone. In one embodiment or in combination with any other embodiment mentioned herein, the feed preparation zone may include a feed hopper. Thus, the compounded CE materials and other solid additives may be stored in a feed hopper, which introduces the combined feed composition into the extrusion zone. The feed preparation zone may further include a mixer, wherein the compounded CE materials and one or more additives may be mixed before being introduced into the hopper. Mixing may be accomplished by any known mixing technique, including but not limited to rolling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling. One or more exemplary solid additives that may be combined with the compounded materials may include one or more chemical foaming agents, one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0024] The combined feed composition from the feed preparation zone can then be introduced into the extrusion zone. The extrusion zone can typically include one or more extruders, which can include single-screw extruders and / or twin-screw extruders. Within the one or more extruders, the feed composition can be introduced into the extruder barrel and conveyed through a die via one or more screws, which forms an extrudate from the feed composition. As the composition is conveyed to the die through the extruder barrel, it can be heated and at least partially melted. Therefore, the term "CE melt composition" as used herein refers to a cellulose ester-based feed composition that has been melted into a flowable molten resin by the extrusion section. Heating can be supplied by an external heater positioned along the outside of the extruder barrel. The shape of the extrudate will typically depend on the shape and size of the die head. As described below, the extrudate can be further shaped by downstream processes.

[0025] While in the extruder, one or more additives may be introduced into the CE molten resin.For example, one or more physical blowing agents may be added to the CE molten resin by injecting the physical blowing agents into the composition being conveyed in the extruder barrel.

[0026] like Figure 4 As depicted, in one embodiment or in combination with any other embodiment mentioned herein, the extrusion zone can include a primary extrusion vessel and a cooling vessel. The primary extrusion vessel and the cooling vessel can be separate devices or combined into a single device. In any case, the feed composition from the feed preparation zone is introduced into the primary extrusion vessel and is at least partially melted as it is conveyed through the extruder barrel as described above, thereby producing a CE molten resin. The CE molten resin exiting the primary extrusion vessel can have a temperature of about 220°C to about 240°C. One or more additives such as a blowing agent can be added to the CE molten resin as it is conveyed through the primary extrusion vessel.

[0027] The CE molten resin from the primary extrusion vessel is then 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 than the primary extrusion vessel. Within the cooling vessel, the CE molten resin may be further mixed to provide a substantially uniform mixture of molten polymer and other additives. The CE molten resin may then be directed through a die and exit the die head to provide a cellulose ester-based extrudate that may be further processed in the sheet forming section of the foam sheet production process. In one embodiment or in combination with any other embodiment mentioned herein, the CE molten 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.

[0028] like Figure 4 As shown, one or more filtration devices can be installed within the extrusion section to filter and remove particulate matter from the CE molten resin. For example, a screen changer filtration device can be installed at the downstream end of the primary extrusion vessel and the secondary extrusion vessel to remove solid components from the CE molten resin before it is directed through the die head to the sheet forming section.

[0029] The sheet forming section can include any of the systems and methods for forming the extrudate into a cellulose ester material sheet that can be used for article forming. The shape of the extrudate will depend on the shape of the die head generally, and the shape of the sheet formed in the sheet forming section can depend on the shape of the die head and other downstream processes. For example, the extrudate can have a generally flat shape, or it can be annular and undergo further processing to form a flat sheet. In the embodiment in which the die has an annular shape, the die can have a diameter of 1 to 40 cm, 2 to 20 cm, 2 to 10 cm and / or 3 to 8 cm. In addition, the size of the thickness of the opening (referred to in this article as "die gap") from which the extrudate ejects can generally be 0.1 to 6.0 mm, 0.1 to 3.0 mm and / or 0.1 to 1.0 mm.

[0030] Figure 5 An exemplary sheet forming section is depicted in FIG. As shown, the CE molten resin is extruded through an annular die and pulled through a forming mandrel. A cooling fluid (e.g., air) can flow through the inside and / or outside of the extrudate to cool the extrudate material when it passes through the mandrel. For example, a cooling fluid can be blown from the mandrel to the die to cool the inner surface of the extrudate between the die and the mandrel. Additionally or alternatively, a cooling fluid can flow through the mandrel to cool the outer surface of the extrudate when it passes through the mandrel.

[0031] A slicer (or slitting device) can be used to open the tubular extrudate, which allows the tubular shape to be formed into a flat sheet. For example, the tubular extrudate can be cut and stretched over a mandrel to a tensioning station, which includes one or more rollers that flatten the extrudate and maintain the necessary tension on the extrudate to continue pulling the extrudate onto the mandrel. The flattened extrudate will typically be in the form of a sheet, which can then be directed to a winding station where the material can be wound for packaging and shipping.

[0032] Reference again Figure 1 and Figure 2 The sheets produced by the sheet production process can be used to form foam products, which will be described in more detail below. Such products are particularly useful in the food service industry. Exemplary products include meat trays. The products can have one or more particularly advantageous properties. For example, the products can be biodegradable and / or compostable, and / or the products can have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0033] Composition

[0034] Said method can comprise preparation and extruding the composition that can be used for downstream processing to form useful goods.For example, in one embodiment or in combination with any other embodiment mentioned herein, extrusion feed material can comprise particulate material, and described particulate material comprises biodegradable polymer, plasticizer and optionally one or more additives, such as those as described herein.In one embodiment or in combination with any other embodiment mentioned herein, feed material and one or more additives (such as those as described herein) can be combined to provide the mixed composition comprising biodegradable polymer, plasticizer and one or more additives.In one embodiment or in combination with any other embodiment mentioned herein, biodegradable polymer comprises cellulose ester.The other details of composition component are provided hereinafter, including biodegradable polymer (for example, cellulose ester), plasticizer and other additives.

[0035] Cellulose esters

[0036] The cellulose esters used as described herein can be any of those known in the art. Cellulose esters useful in embodiments herein typically comprise repeating units of the following structure:

[0037]

[0038] Wherein R1, R2 and R3 are independently selected from hydrogen, acetyl, propyl or butyl. The substitution level of cellulose esters is usually expressed as the degree of substitution (DS), which is the average number of non-OH substituents per anhydroglucose unit (AGU). Typically, conventional cellulose contains three hydroxyl groups that can be substituted in each AGU unit; therefore, the value of DS can be between zero and three. Natural cellulose is a large polysaccharide with a degree of polymerization of 250-5,000 even after pulping and purification, and therefore the assumption that the maximum DS is 3.0 is roughly correct. Since DS is a statistical average, a value of 1 does not guarantee that each AGU has a single substituent. In some cases, there may be unsubstituted anhydroglucose units, some with two substituents and some with three substituents, and typically, the value will be a non-integer. The total DS is defined as the average number of all substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to a specific substituent, such as, for example, a hydroxyl group or an acetyl group. In one embodiment or in combination with any other embodiments, n is an integer ranging from 25 to 250, or from 25 to 200, or from 25 to 150, or from 25 to 100, or from 25 to 75.

[0039] In one embodiment or in combination with any other embodiment, the cellulose ester has at least 2 anhydroglucose rings and can have between at least 50 and up to 5,000 anhydroglucose rings or between at least 50 and less than 150 anhydroglucose rings. The number of anhydroglucose units per molecule is defined as the degree of polymerization (DP) of the cellulose ester. In one embodiment or in combination with any other embodiment, the cellulose ester can have an intrinsic viscosity (IV) of about 0.2 to about 3.0 deciliters per gram, or about 0.5 to about 1.8, or about 1 to about 1.5, measured for a 0.25 gram sample in 100 ml of a 60 / 40 weight solution of phenol / tetrachloroethane at a temperature of 25°C. In one embodiment or in combination with any other embodiment, the cellulose ester useful herein can 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, and the substituted ester is an acetyl group.

[0040] Cellulose esters can be produced by any method known in the art. Examples of methods for producing cellulose esters are taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th edition, Volume 5, Wiley-Interscience, New York (2004), pages 394-444. Cellulose is the starting material for producing cellulose esters and can be obtained from various grades and sources, such as cotton linters, softwood pulp, hardwood pulp, corn fiber and other agricultural sources, and bacterial cellulose.

[0041] One method for producing cellulose esters is to esterify the cellulose by mixing it with an appropriate organic acid, anhydride, and a catalyst. The cellulose is then converted into a cellulose triester. The esters are then hydrolyzed by adding a water-acid mixture to the cellulose triester, which can then be filtered to remove any gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester can then be washed with water to remove reaction by-products, followed by dehydration and drying.

[0042] The cellulose triester to be hydrolyzed may have three acetyl substituents. These cellulose esters may be prepared by many methods known to those skilled in the art. For example, cellulose esters may be prepared by the presence of a catalyst such as H2SO 4) Cellulose triesters can also be prepared by homogeneous acylation of cellulose dissolved in a suitable solvent such as LiCl / DMAc or LiCl / NMP.

[0043] Those skilled in the art will appreciate that the commercial term cellulose triesters also encompass cellulose esters that are not fully 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.

[0044] After cellulose is esterified to a triester, some of the acyl substituents can be removed by hydrolysis or alcoholysis to produce a secondary cellulose ester. As previously mentioned, the distribution of the acyl substituents can be random or non-random, depending on the specific method used. Secondary cellulose esters can also be prepared directly without hydrolysis by using a limited amount of acylating agent. This method is particularly useful when the reaction is carried out in a solvent that will dissolve the cellulose. All of these methods produce cellulose esters useful in the present invention.

[0045] In one embodiment or combination with any of the recited embodiments, the cellulose acetate is 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 a solvent and a polystyrene equivalent according to ASTM D6474. In one embodiment or combination with any of the other embodiments, the cellulose acetate composition comprises 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 a solvent and a polystyrene equivalent according to ASTM D6474. 10,000 to 90,000; or 10,000 to 80,000; or 10,000 to 70,000; or 10,000 to 60,000; or 10,000 to less than 60,000; or 10,000 to less than 55,000; or 10,000 to 50,000; or 10,000 to less than 50,000; or 10,000 to less than 45,000; or 10,000 to 40,000; or 10,000 to 30,000; or 20,000 to less than 60,000; or 20,000 to less than 55,000; or 20, or 30,000 to less than 60,000; or 30,000 to less than 55,000; or 30,000 to 50,000; or 30,000 to less than 50,000; or 30,000 to less than 45,000; or 30,000 to 40,000; or 30,000 to 35,000; or 20,000 to 30,000; or 30,000 to less than 60,000; or 30,000 to less than 55,000; or 30,000 to 50,000; or 30,000 to less than 50,000; or 30,000 to less than 45,000; or 30,000 to 40,000; or 30,000 to 35,000.

[0046] The most common commercial secondary cellulose esters are produced by an initial acid-catalyzed heterogeneous acylation of cellulose to form cellulose triesters. After obtaining a homogeneous solution of the cellulose triesters in the corresponding carboxylic acid, the cellulose triesters are then subjected to hydrolysis until the desired degree of substitution is achieved. After separation, random secondary cellulose esters are obtained. That is, the relative degree of substitution (RDS) of each hydroxyl group is approximately equal.

[0047] The cellulose esters useful in the present invention can be prepared using techniques known in the art and can be selected from various types of cellulose esters, such as, for example, cellulose esters available from Eastman Chemical Company, Kingsport, TN, USA, e.g., Eastman TM Cellulose acetate CA 398-30 and Eastman TM Cellulose acetate CA 398-10, Eastman TM CAP 485-20 Cellulose acetate propionate; Eastman TM CAB 381-2 Cellulose acetate butyrate.

[0048] In one embodiment or in combination with any other embodiment, cellulose esters can be prepared by converting cellulose into cellulose esters using reactants obtained from recycled materials (e.g., recycled plastic content syngas sources). In one embodiment or in combination with any other embodiment, such reactants can be cellulosic reactants including organic acids and / or anhydrides used in esterification or acylation reactions of cellulose, e.g., as discussed herein.

[0049] In one embodiment of the present invention or in combination with any of the mentioned embodiments, or in combination with any of the mentioned embodiments, there is provided a cellulose ester composition comprising at least one recycled cellulose ester, wherein the cellulose ester has at least one substituent on an anhydroglucose unit (AU) derived from recycled content material (e.g., recycled plastic content syngas).

[0050] In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises 50 to 99 wt%, or 60 to 99 wt%, or 70 to 99 wt%, or 80 to 99 wt%, or 90 to 99 wt%, 50 to 90 wt%, or 60 to 90 wt%, or 70 to 90 wt%, or 80 to 90 wt%, or 90 to 99 wt%, or 50 to 80 wt%, or 60 to 80 wt%, or 70 to 80 wt%, or 50 to 70 wt%, or 60 to 70 wt%, or 50 to 60 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein may comprise a combination, blend, or mixture of two or more different types of cellulose esters. For example, in some embodiments, the cellulose ester used herein may be composed of a blend of two or more cellulose esters having different DSACs; however, the blend may have a total DSAC between 2.2 and 2.8.

[0051] plasticizers

[0052] In one embodiment or in combination with any other embodiment, the cellulose ester composition described herein may include at least one plasticizer. Plasticizers reduce the melting temperature (i.e., Tg) and / or melt viscosity of the cellulose ester. Plasticizers for cellulose esters may include triacetin, diacetin, dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, poly (ethylene glycol) MW 200-600, dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl o-benzoylbenzoate, triethylene glycol dipropionate, 1,2-epoxypropylphenyl glycol, 1,2-epoxypropyl(m-tolyl) glycol, 1,2-epoxypropyl(o-tolyl) glycol, β-oxyethyl cyclohexenecarboxylate, diethylene glycol bis(cyclohexanoate), triethyl citrate, polyethylene glycol, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinyl pyrrolidone and ethylene glycol tribenzoate, benzoate-containing plasticizers such as Benzoflex TM Plasticizer series, poly (alkyl succinates) such as poly (butyl succinate), polyether sulfone, o-toluene p-toluenesulfonate, N-ethyl toluenesulfonamide, adipate-based plasticizers, soybean oil epoxides such as Paraplex TM Plasticizer series, sucrose-based plasticizer, dibutyl sebacate, tributyrin, sucrose acetate isobutyrate, Resolflex TMSeries plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (e.g., ethyl phthaloyl glycolate "EPEG" and methyl phthaloyl glycolate "MPEG"), methoxy polyethylene glycol, 2,2,4-trimethylpentane-1,3-diyl bis(2-methylpropionate) and polycaprolactone. In some embodiments, the plasticizer used herein may comprise a combination or mixture of two or more different types of plasticizers.

[0053] In one embodiment or in combination with any other embodiment, the plasticizer is a food compliance plasticizer. Food compliance means meeting applicable food additives and / or food contact regulations, wherein the plasticizer is approved for use or is considered safe by at least one (national or regional) food safety regulatory agency (or organization), such as listed in 21CFR Food Additive Regulations or otherwise listed as generally recognized as safe (GRAS) by the U.S. FDA. In one embodiment or in combination with any other embodiment, the food compliance plasticizer is triacetin or polyethylene glycol (PEG) with a molecular weight of about 200 to about 600. In one embodiment or in combination with any other embodiment, examples of food-compliant plasticizers that may be considered may include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinyl pyrrolidone, and glycol tribenzoate.

[0054] In one embodiment or combination with any other embodiment, the plasticizer is present in an amount sufficient to allow the cellulose ester composition to be melt processed (or thermoformed) into useful articles, such as disposable plastic articles, in conventional melt processing equipment. In one embodiment or combination with any other embodiment, the plasticizer is present in an amount of 1 to 40 wt% for most thermoplastic processing; or 5 to 25 wt%, or 10 to 25 wt%, or 12 to 20 wt%, based on the weight of the cellulose ester composition. In one embodiment or combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be accomplished with plasticizer levels in the range of 10-30, or 12-25, or 15-20, or 10-25 wt%, based on the weight of the cellulose ester composition.

[0055] 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, benzoate-containing plasticizers such as Benzoflex, TM Plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfones, adipate-based plasticizers, soybean oil epoxides such as Paraplex TM Plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributyrin, Resoflex TM Series of plasticizers, triphenyl phosphate, glycolate, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diylbis(2-methylpropionate) and polycaprolactone.

[0056] In one embodiment or in combination with any other embodiment, the cellulose ester composition can contain a plasticizer selected from the group consisting of PEG and MPEG (methoxy PEG). The polyethylene glycol or methoxy polyethylene glycol composition has an average molecular weight of 200 to 600 Daltons, wherein the composition is melt processable, biodegradable, and disintegratable.

[0057] In one embodiment or in combination with any other embodiment, the composition comprises polyethylene glycol or methoxy PEG having an average molecular weight of 300 to 550 Daltons.

[0058] 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.

[0059] In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises at least one plasticizer (as described herein) in an amount of 1 to 40 wt%, or 5 to 40 wt%, or 10 to 40 wt%, or 12 to 40 wt%, 13 to 40 wt%, or 15 to 40 wt%, or greater than 15 to 40 wt%, or 17 to 40 wt%, or 20 to 40 wt%, or 25 to 40 wt%, or 5 to 35 wt%, or 10 to 35 wt%, or 13 to 35 wt%, or 15 to 35 wt%, or greater than 15 to 35 wt%, or 17 to 35 wt%, or 20 to 35 wt%, or 5 to 30 wt%, or 10 to 30 wt%, or 13 to 30 wt%, or 15 to 30 wt%. %, or greater than 15 to 30 wt%, or 17 to 30 wt%, or 5 to 25 wt%, or 10 to 25 wt%, or 13 to 25 wt%, or 15 to 25 wt%, or greater than 15 to 25 wt%, or 17 to 25 wt%, or 5 to 20 wt%, or 10 to 20 wt%, or 13 to 20 wt%, or 15 to 20 wt%, or greater than 15 to 20 wt%, or 17 to 20 wt%, or 5 to 17 wt%, or 10 to 17 wt%, or 13 to 17 wt%, or 15 to 17 wt%, or greater than 15 to 17 wt%, or 5 to less than 17 wt%, or 10 to less than 17 wt%, or 13 to less than 17 wt%, or 15 to less than 17 wt%, all based on the total weight of the cellulose ester composition.

[0060] In one embodiment or in combination with any other embodiment, the at least one plasticizer comprises or is a food acceptable or FDA approved plasticizer. In one embodiment or in combination with any other embodiment, the food acceptable or FDA approved plasticizer comprises or is triacetin or PEG MW 300 to 500.

[0061] Biodegradable polymers

[0062] In one embodiment or in combination with any other embodiment, the cellulose ester composition described herein comprises a biodegradable cellulose ester (BCE) component comprising at least one BCE, which may include one or more of the cellulose esters described herein; and a biodegradable polymer component comprising at least one other biodegradable polymer (not BCE). In one embodiment or in combination with any other embodiment mentioned herein, the other biodegradable polymer can be selected from polyhydroxyalkanoates (PHA and PHB), polylactic acid (PLA), polycaprolactone polymers (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, derivatives thereof, and combinations thereof. In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises two or more biodegradable polymers. In one embodiment or in combination with any other embodiment, the cellulose ester composition contains a biodegradable polymer (other than BCE) in an amount of 0.1 to less than 50 wt%, or 1 to 40 wt%, or 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, based on the cellulose ester composition. In one embodiment or in combination with any other embodiment mentioned herein, the cellulose ester composition contains a biodegradable polymer (other than BCE) in an amount of 0.1 to less than 50 wt%, or 1 to 40 wt%, or 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, based on the total amount of BCE and biodegradable polymer. In one embodiment or in combination with any other embodiment, the at least one biodegradable polymer comprises a polymer having a molecular weight of 10,000 to 1,000,000, or 50,000 to 1,000,000, or 100,000 to 1,000,000, or 250,000 to 1,000,000, or 500,000 to 1,000,000, or 600,000 to 1,000,000, or 600,000 to 1,000,000. In one embodiment or in combination with any other embodiment, the PHA can comprise polyhydroxybutyrate-co-hydroxyhexanoate.

[0063] Nucleating agent

[0064] Nucleating agent means a chemical or physical material that provides sites for the formation of cells in a molten formulated mixture (such as in a CE molten resin). As will be described in more detail below, the nucleating agent can be added to the compounded CE material during the compounding process. Alternatively or in addition, the nucleating agent can be added during the foam sheet production process. For example, the nucleating agent can be blended with the formulation in the extruder hopper introduced into the extrusion section. Alternatively, the nucleating agent can be added to the CE molten resin in the extruder itself. Nucleating agents can include physical nucleating agents and chemical nucleating agents. A physical nucleating agent is a material that is immiscible with the polymer matrix of the CE molten resin at the extrusion temperature of the extrusion section. A chemical nucleating agent is a material that reacts (e.g., decomposes) to form a physical nucleating agent during the extrusion process (e.g., at the extrusion temperature in the extruder). Therefore, a chemical nucleating agent can be considered to be (and is referred to herein as) a precursor to a physical nucleating agent formed in situ.

[0065] Suitable physical nucleating agents will include fine particles of 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 will have 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 microns. However, in some other embodiments, particles having nanoscale dimensions may be preferred. Furthermore, in some embodiments, the physical nucleating agent will preferably have a high aspect ratio (i.e., width:height). For example, in some embodiments, the average aspect ratio of the physical nucleating agent will be 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. In addition, as described above, the physical nucleating agent should be immiscible with the polymer matrix of the CE molten resin at the extrusion temperature of the extrusion zone. Thus, in some embodiments, the physical nucleating agent should 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 can be selected such that it has the ability to recrystallize upon cooling after melting.

[0066] Examples of suitable inorganic physical nucleating agents include, but are not limited to, minerals such as talc, CaCO 3 , mica, and mixtures of at least two of the foregoing. A representative example is Heritage Plastics HT6000 linear low density polyethylene (LLDPE) based talc concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon oxide, titanium oxide, magnesium oxide, aluminum oxide and calcium silicate, barium sulfate, kaolin, aluminum 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 will comprise an oxide, such as a metal oxide or mixed metal oxide, such as an oxide selected from one or more of the following: aluminum oxide, antimony oxide, arsenic oxide, bismuth oxide, boron oxide, calcium oxide, gallium oxide, iron oxide, lithium oxide, magnesium oxide, silicon oxide and titanium oxide. In other embodiments, the inorganic nucleating agent will comprise a silicate, for example, a silicate selected from one or more of the following: magnesium silicate and calcium silicate.

[0067] It has been found that biodegradable natural particulate materials (e.g., organic nucleating agents) derived from renewable organic sources are also used as effective physical nucleating agents. Natural materials that can be used as physical nucleating agents include materials consisting of cellulose fiber and / or cellulose starch. Examples include, but are not limited to, almond shell powder, animal fiber, apricot shell powder, bamboo powder, bark powder, clam shell powder, coconut shell powder, coconut chaff, cork powder, corn cob powder, corn cob crumbs, cotton seed shells, cotton linter and fiber, hazelnut shell powder, kenaf powder, natural fiber, nut shells and powder, oat fiber powder, olive kernel powder, peanut shell powder, pecan shell powder, pine nut shell powder, pistachio shell powder, plant fiber, rice husk powder, rice husk grains, rice husks, soy flour, starch powder (hydrophobicity), walnut shell powder, wheat bran, wheat husks and wood flour. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, stearic acid metal salts, carbon black and dolomite.

[0068] As described above, suitable chemical nucleating agents (or precursors to in-situ formed physical nucleating agents) are configured to decompose upon reaching a threshold chemical reaction temperature to create cell nucleation sites in the CE molten resin. These small cells serve as nucleation sites for larger cell growth 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 extrusion of the particulate material.

[0069] 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 caproic acid. A representative example is HYDROCEROL TMCF-40E (available from Clariant Corporation) contains citric acid and a crystal nucleating agent. In some embodiments, the chemical nucleating agent will include a combination of an acid and an alkali, such as a carbonate, which can include sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, etc. For example, a representative example of a chemical nucleating agent is a combination of citric acid and sodium bicarbonate. In some embodiments, the chemical nucleating agent can include a carrier in which the active component of the nucleating agent is dispersed. For example, another representative example of a chemical nucleating agent is a combination of citric acid, sodium bicarbonate, and a carrier. In some embodiments, the carrier can include polystyrene. However, the carrier can include other compositions, such as various biopolymers (e.g., polybutylene succinate, Capa polyester, etc.), polyolefins, acrylic copolymers (e.g., ethylene methyl acrylate), etc. In some such embodiments, citric acid and sodium bicarbonate can constitute about half (wt%) of the chemical nucleating agent, while the carrier constitutes the remaining half (wt%). In addition, in some such embodiments, the sodium bicarbonate in the chemical nucleating agent can be more than citric acid. For example, sodium bicarbonate may be about three times as present (wt %) as citric acid in a chemical nucleating agent.It should also be understood that in some embodiments, a carrier may not be needed or used, such as where the nucleating agent is Hecofoam or Hydrocerol.

[0070] In one embodiment or combination with any embodiment mentioned herein, the nucleating agent is present in an amount of 0.1 to 10 wt%, 0.1 to 5.0 wt%, at least 0.1 wt%, at least 0.25 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.25 wt%, at least 1.5 wt%, at least 1.75 wt%, at least 2.0 wt%, at least 2.25 wt%, at least 2.5 wt%, at least 2.75 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt% and / or less than 7.5 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agent used herein can comprise a combination or mixture of two or more different types of nucleating agents.

[0071] Note that, whether in the form of compounded CE materials or CE molten resins, cellulose ester materials are generally able to accept the maximum amount of nucleating agents that can serve to form nucleation sites. Any remaining nucleating agents added to the cellulose ester material will be retained as fillers. Based on the type of filler used, fillers can provide various properties for the resulting cellulose ester foam and / or product. For example, some fillers can provide increased / decreased density, ductility, Young's modulus, yield strength, heat distortion temperature, permeability, impact resistance, elongation at break, adhesion characteristics, biodegradability, etc. of the cellulose ester material. Fillers can also be used to change the visual characteristics (e.g., color, opacity, etc.) and tactile characteristics (e.g., material continuity, surface roughness, etc.) of the cellulose ester material.

[0072] foaming agent

[0073] A blowing agent refers to a physical or chemical material (or combination of materials) that is used to expand the nucleation sites. The blowing agent may include a chemical blowing agent, a physical blowing agent, a combination thereof, or several types of chemical and physical blowing agents. The function of the blowing agent is to reduce the density of the material by enlarging the cells formed in the molten formulation at the nucleation sites. The blowing agent can be added to the CE molten resin in the extruder. It has been surprisingly found that the hygroscopic properties of biodegradable particulate natural fillers allow them to absorb water and carry the absorbed water into the molten resin mixture, where the water can act as a physical blowing agent.

[0074] The example of physical foaming agent comprises H2O, N2, CO2, alkane, olefin, ether, ketone, argon, helium, air or mixture.In addition, it has been surprisingly found that the hygroscopic property of biodegradable particulate natural filler allows them to absorb moisture and bring the absorbed water into the molten resin mixture, wherein water can serve as physical foaming agent.Hygroscopic biodegradable natural filler can be formulated into composition and allows to absorb moisture before the foaming process, then releases water in the foaming process and serves as physical foaming agent.Beneficially, water can also be used as the plasticizer for cellulose ester resin.In addition, in some embodiments, physical foaming agent can comprise hydrocarbon, such as pentane / isopentane or butane / isobutane.Other hydrocarbons can comprise propane, ethane, methane, hexane, cyclohexane, cyclopentane, cyclobutene etc.

[0075] Chemical foaming agents are materials that degrade or react to produce gases (e.g., CO2 or N2). Such gases expand the cells in the molten resin mixture and / or the resulting foam mixture to produce a structural material having a plurality of gas voids dispersed throughout. Chemical foaming agents can be endothermic or exothermic. Chemical foaming agents typically degrade at a specific temperature to decompose and release gas. Examples of chemical foaming agents include azodicarbonamide, acids (e.g., citric acid), and carbonates such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, and the like, and combinations thereof.

[0076] In one embodiment or combination with any embodiment mentioned herein, the blowing agent is present in an amount of 0.3 to 1.5 wt%, or 0.3 to 2.0 wt%, or 0.3 to 2.5 wt%, or 0.3 to 3.0 wt%, or 0.3 to 3.5 wt%, or 0.3 to 4.0 wt%, or 0.3 to 8%, or 1.3 to 1.5 wt%, or 1.3 to 2.0 wt%, or 1.3 to 2.5 wt%, or 1.3 to 3.0 wt%. t%, or 1.3 to 3.5 wt%, or 1.3 to 4.0 wt%, or 1.3 to 4.5 wt%, or 1.3 to 5.0 wt%, or 1.3 to 5.5 wt%, or 1.5 to 3.0 wt%, or 1.5 to 4.0 wt%, or 1.5 to 5.0 wt%, or 1.5 to 6.0 wt%, or 2.0 to 3.0 wt%, or 2.0 to 4.0 wt%, or 2.0 to 5.0 wt%, or 2.0 to 6.0 wt% %, or 2.5 to 3.0 wt%, or 2.5 to 4.0 wt%, or 2.5 to 5.0 wt%, or 2.5 to 6.0 wt%, or 3.0 to 4.0 wt%, or 3.0 to 5.0 wt%, or 3.0 to 6.0 wt%, or 0.0 to 9.0 wt%, or 0.5 to 9.0 wt%, or 1.0 to 9.0 wt%, or 1.5 to 9.0 wt%, or 2.0 to 9.0 wt%, or 2.5 to 9.0 wt%, or %, or 3.0 to 9.0 wt %, or 3.5 to 9.0 wt %, or 4.0 to 9.0 wt %, or 4.5 to 9.0 wt %, or 5.0 to 9.0 wt %, or 5.5 to 9.0 wt %, or 6.0 to 9.0 wt %, or 6.5 to 9.0 wt %, or 7.0 to 9.0 wt %, or 7.5 to 9.0 wt %, or 8.0 to 9.0 wt %, or 8.5 to 9.0 wt %, all based on the total weight of the cellulose ester composition. In some embodiments, the blowing agent used herein may comprise a combination or mixture of two or more different types of blowing agents.

[0077] Surface modification additives

[0078] Surface modification additives refer to materials that can be added to a cellulose ester composition to modify the structure of the composition (or the resulting foam article) and thereby improve the processing of the cellulose ester composition. For example, the inventors of the present application have discovered that adding a surface modification additive to compounded CE materials (e.g., to pellets during compounding) or to CE molten resin (e.g., during extrusion) can improve processing by reducing unwanted adhesion of the CE molten resin to the die or mandrel (or other components of the foam sheet production process). This reduction in adhesion can be achieved by the surface modification additive inhibiting the fusion of the cellulose ester caused by the plasticizer. The addition of a surface modification additive can also reduce blockage of the cellulose ester foam sheet produced in the sheet forming section. In addition, the surface modification additive can also improve the foam sheet production process by allowing the process to be carried out at lower temperatures.

[0079] Furthermore, in some embodiments, the surface modification additive can function as an antistatic additive, suppressing sparks or arcs in the CE molten resin. Suppressing sparks or arcs can be particularly important when hydrocarbons are used as blowing agents, in order to reduce the chance of the hydrocarbons igniting and causing a fire. Advantageously, the surface modification additive can also reduce the outward diffusion of blowing agents, such as hydrocarbons, from the foam sheet or the resulting article. In some embodiments, the hydrocarbon itself can be used as a surface modification additive.

[0080] However, more general examples of surface modification additives that can be used in compounding CE materials (e.g., during compounding) or CE melt resins (e.g., in foam sheet production processes) according to embodiments of the present invention include fatty acids such as palmitic acid, tallow fatty acid, stearic acid, oleic acid, linoleic acid and linolenic acid, arachidic acid / behenic acid, behenic acid, and erucic acid. Surface modification additives may also include fatty acid amides such as erucamide, oleamide, stearamide, behenamide, secondary amides, and bisamides.

[0081] The other example of surface modification additive can include glyceride and / or stearate, such as monoglyceride, diglyceride and triglyceride.Monoglyceride can include glyceryl monostearate or monoglyceride derivatives, such as diacetyl tartaric acid ester (DATEM), ethoxylated monoglyceride, succinyl monoglyceride and propylene glycol monoester (PGME) of monoglyceride and diglyceride.The example of surface modification additive can also include metal stearate, such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate and / or their combination (for example, calcium stearate / zinc stearate).The example of surface modification additive can also include wax, such as polyolefin wax (polypropylene wax and polyethylene wax), oxidized olefin wax, ethylene acrylic acid (EAA) copolymer wax, ethylene methyl acrylate (EMA) copolymer wax, EAA ionomer wax, acrylic acid wax and / or natural wax, such as rice bran wax, sunflower wax, sugarcane wax, candelilla wax, soybean wax, beeswax, candelilla wax and carnauba wax.

[0082] Other non-exclusive examples of surface modification additives include aliphatic diesters (for example, dioctyl adipate), polyglycol diesters, alkyl alkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters and alkyl monoesters. In addition, various oils can be used as surface modification additives, such as aromatic oils, naphthenic oils, glyceride oils, silicone oils and epoxidized oils (for example, soybean oil and linseed oil). Therefore, in some embodiments, surface modification additives include plasticizers, such as aliphatic diester plasticizers, polyester plasticizers etc. In addition, in some embodiments, surface modification additives can include polyhedral oligomeric silsesquioxanes (POSS).

[0083] More generally, the surface modification additives used in embodiments of the present invention can have a lower polarity than the cellulose ester in the compounded CE material (e.g., during compounding) or the CE melt resin (e.g., in the foam sheet production process). For example, the surface modification additive can have (based on the Hansen solubility parameter): less than 25 MPa 1 / 2 , less than 20MPa 1 / 2 , or less than 19.5MPa 1 / 2 Total solubility parameter δ; less than 18MPa 1 / 2 , less than 16MPa 1 / 2 , or less than 14MPa 1 / 2 The dispersion solubility parameter δ d Less than 12MPa 1 / 2 , less than 8MPa 1 / 2 , or less than 4MPa 1 / 2 Solubility parameter δ of the dipole intermolecular force d ; and / or less than 11MPa1 / 2 , less than 10MPa 1 / 2 , or less than 9MPa 1 / 2 The hydrogen bond solubility parameter δ h However, in some other embodiments, the surface modification additive used in embodiments of the present invention may have a higher polarity than the cellulose ester in the compounded CE material (e.g., during compounding) or the CE melt resin (e.g., in a foam sheet production process). For example, the surface modification additive may have (based on Hansen Solubility Parameters): greater than 21.5 MPa 1 / 2 , greater than 23MPa 1 / 2 , or greater than 25MPa 1 / 2 In some embodiments, the surface modification additive may have a boiling point greater than 200°C, greater than 220°C, greater than 240°C, greater than 260°C, greater than 280°C, or greater than 300°C. In addition, the surface modification additive may have a molecular weight greater than 100 g / mol, greater than 150 g / mol, greater than 220 g / mol, greater than 260 g / mol, greater than 300 g / mol, or greater than 340 g / mol and / or no more than 1000 g / mol, no more than 2500 g / mol, or no more than 5000 g / mol. Still further, it may be preferred that the surface modification additive is insoluble in one or more plasticizers used in the cellulose ester composition. For example, it may be preferred that the surface modification additive is insoluble in triacetin. Finally, in some embodiments, the surface modification additive may be biodegradable and / or food compliant or FDA approved.

[0084] In one embodiment or combination with any embodiment mentioned herein, the surface modification additive is present in an amount from 0.05 to 0.75 wt%, or 0.05 to 1.0 wt%, or 0.05 to 2.5 wt%, or 0.05 to 5.0 wt%, or 0.75 to 1.0 wt%, or 0.75 to 2.5 wt%, or 0.75 to 5.0 wt%, or 0.1 to 1.0 wt%, or 0.1 to 2.5 wt%, 0.1 to 5.0 wt%, or 1.0 to 2.5 wt%, or 1.0 to 5.0 wt%, or 2.5 to 5.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the surface modification additive used herein can comprise a combination or mixture of two or more different types of surface modification additives.

[0085] Products

[0086] The above-mentioned extrusion section and / or sheet forming section can be used to form an extruded sheet of cellulose ester foam. Such extruded sheet comprises a structural material having a plurality of gas voids dispersed throughout. Such gas voids are formed by the expansion of a blowing agent in the form of a gas in a cellulose polymer melt. The structural material is based on cellulose ester and has a specific amount of constituent components of the structural material (e.g., cellulose ester, plasticizer, nucleating agent, surface modification additive, etc.) that have been described in more detail above. Articles can be formed from extruded sheets of foam according to the embodiment and can be particularly used in the food service industry. Exemplary articles include meat trays. Articles can have one or more particularly advantageous properties. For example, the article can have preferential water absorption properties, be biodegradable and / or compostable, and / or the article can have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0087] Such cellulose ester foam articles can be formed from a cellulose ester foam sheet by thermoforming, wherein heat and optionally pressure are applied to the foam sheet within a mold to produce a three-dimensional article that retains its shape after being released from the mold. For example, in some embodiments, the foam sheet will be heated to a surface temperature that is 40°C to 100°C, 50°C to 80°C, or 50°C to 70°C higher than the Tg of the foam sheet. In some embodiments, the Tg of the foam sheet will be about 120°C. Thus, the thermoforming process can heat the foam sheet to a surface temperature of 150°C to 210°C or 160°C to 200°C.

[0088] In more detail, embodiments of the present invention may include foam articles in the form of foam trays, such as Figure 6 As shown, the foam tray can be configured as a food tray to support one or more food items, such as meat. As shown, the foam tray can include a substantially planar base and a rim that rises above the base and extends around the periphery of the foam tray. The top surface of the base and the surrounding rim define a receiving area (e.g., a bowl) in which items (e.g., meat, cheese, vegetables, fruit, or other food) can be received and supported.

[0089] The foam tray formed according to the embodiment of the present invention can be formed into various sizes. For example, Figure 6 As illustrated, the tray can have a width "W" in the range of 2-12 inches, 3-10 inches, or 5-9 inches and a length "L" of 4-24 inches, 5-18 inches, or 6-15 inches. Thus, in some embodiments, the tray can have a length of 1.2-4 times, 1.4-3 times, or 1.5-2 times the width of the tray.

[0090] The area of ​​the base 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 inches, and the rim width (i.e., the lateral distance "Rw" measured from one side of the tray to the point where the rim meets the base, such as Figure 6 05 in., or 0.25-0.50 in. Alternatively, the rim width "Rw" may be about 0.01W to 0.1W or about 0.03W to 0.06W, where "W" represents the tray width as discussed above. The ratio of the base area to the rim area may be 1-10, 1.5-6, or 2-4. Additionally, the tray may have a depth (measured from the top of the rim to the top surface of the base) 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. Furthermore, the tray or other article can have a thickness (i.e., the thickness of the cellulose ester foam) of 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. Alternatively or additionally, the tray or other article can have a thickness (i.e., the thickness of the cellulose ester foam) of 100-400 mils, 120-300 mils, or 150-250 mils.

[0091] Advantageously, the foam tray can have preferential water absorption properties. For example, when using a foam tray to support meat, it is preferred that the tray not absorb liquid that drains from the meat. The foam tray can be subjected to a water absorption test (i.e., a moisture absorption test) using the following test procedure, which includes the following steps: (1) weighing the foam tray to obtain the original tray weight; (2) filling the receiving area of ​​the tray 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., eight hours); (4) emptying the tray of the water supported in the receiving area; (5) gently wiping the tray to remove any excess water remaining on the surface of the tray; (6) weighing the water-exposed tray to obtain the water-exposed tray weight; and (7) calculating the percent weight increase of the water-exposed tray weight relative to the original tray weight. As used herein, the "one-hour water absorption test" is defined as the above procedure, wherein the equilibration step (3) is one hour. Additionally, as used herein, the "eighteen-hour water absorption test" is defined as the above procedure, wherein the equilibration step (3) is eighteen hours.

[0092] According to embodiments of the present invention, after the tray of the present invention is filled with water and allowed to equilibrate at room temperature for one hour (i.e., under a one-hour water absorption test), the tray (after removing the water from the receiving area of ​​the tray) may have a weight increase of 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 additionally, after the tray of the present invention is filled with water and allowed to equilibrate at room temperature overnight (i.e., under an eighteen-hour water absorption test), the tray (after removing the water from the receiving area of ​​the tray) may have a weight increase of less than 20%, less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, and / or less than 10.5%.

[0093] After the one-hour water absorption test and / or the eighteen-hour water absorption test, the foam tray can be further subjected to a "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 refrigerator overnight (i.e., eighteen hours); (2) removing the frozen tray from the refrigerator; (3) allowing the frozen tray to thaw overnight (i.e., eighteen hours) at room temperature; (4) filling the receiving area of ​​the thawed foam tray with water; (5) allowing the filled tray to equilibrate at room temperature for twelve hours; (6) emptying the tray of water supported in the receiving area; (7) gently wiping the empty tray to remove any excess water remaining on the surface of the tray; (8) weighing the tray exposed to water to obtain the weight of the tray exposed to water; and (9) calculating the percentage of weight increase of the weight of the tray exposed to water relative to the original weight of the tray. According to embodiments of the present invention, after the tray is subjected to the eighteen-hour water absorption test and the freeze-thaw test, the tray can have a weight increase of less than 30%, less than 25%, less than 20%, and / or less than 15%.

[0094] In order to enhance the ability of the foam tray to minimize water absorption, a hydrophobic cap layer can be formed on the outer surface of the foam tray. This hydrophobic cap layer can be formed by using a hydrophobic additive (e.g., stearic acid, calcium stearate, zinc stearate, glyceryl monostearate, etc.) in the material used to form the cellulose ester foam sheet. For example, the hydrophobic additive can be added to the compounded CE material (e.g., during the compounding process) or added to the CE molten resin (e.g., during the foam sheet production process). Alternatively or in addition, a hydrophobic cap layer can be formed on the surface of the foam article by co-extruding, laminating and / or coating the hydrophobic material onto the foam sheet and / or foam article. Because, as discussed above, foam articles can be used to support food items, such as meat, it may be beneficial to form a hydrophobic cap layer on the upper surface of the foam article that supports the food item (e.g., on the surface of the foam article and / or tray that forms the bowl or receiving area).

[0095] Several sample trays were formed and tested using a water absorption test and a freeze-thaw test. The trays were formed from cellulose ester foam sheets extruded using a tandem extruder system. The extruded cellulose ester molten resin contained cellulose diacetate having a degree of substitution of 2.52, a melting point of 230°C-250°C, and a Tg of 189°C. The molten resin was plasticized with 15 to 20 wt.% loading of triacetin. Talc was used as a nucleating agent and mixed into the molten resin together with a physical foaming agent in a twin-screw extruder of the tandem extruder system. The resulting molten resin was transferred to a single-screw extruder where a cellulose ester foam sheet was extruded using an annular die. The foam sheet was stretched, cut, and thermoformed to form a foam tray. Table 1 shows the results of four samples subjected to a one-hour water absorption test. Table 2 shows the results of four samples subjected to an eighteen-hour water absorption test, and Table 3 shows the results of two samples subjected to a freeze-thaw test. Note that for each sample, at least three foam trays were used, and the measurement results were averaged to provide the results shown below.

[0096] Table 1

[0097] Example# Weight gain -1 hour (%) (mean ± SD) 1 3.9±0.3 2 6.5±0.6 3 4.6±0.2 4 6.3±1.6

[0098] Table 2.

[0099] Example# Weight gain - overnight (%) (mean ± SD) 5 10.5±0.3 6 11.8±0.7 7 13.3±0.7 8 13.3±1.9

[0100] Table 3.

[0101] Example# Overnight weight gain (%) Weight increase after freeze-thaw cycles (%) 9 14.3 14.9 10 24.1 26.4

[0102] Embodiments provide the above-mentioned foam tray to be formed according to the method described herein. In particular, a mixed composition comprising 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 can include a generally planar base and an edge extending upward from the base and around the periphery of the tray. The resulting foam tray can be used to support food products, such as meat. Therefore, in some embodiments, an absorbent pad will be placed on top of the base, within the receiving area of ​​the tray, so that liquid from the meat (or other food) can be absorbed by the pad. In addition, a shrink film or overwrap film can be wrapped around the tray to securely hold the meat therein and protect it from environmental influences. Beneficially, the tray described herein can be formed with a preferred density, which allows the tray to be formed on an economical and efficient basis. This preferred density can be achieved by post-expansion of the foam, especially when a cellulose ester material is used in the tray.

[0103] In more detail, according to an embodiment of the present invention, a foam sheet can be produced from a cellulose ester composition, for example, by extrusion. The resulting foam sheet can have a certain extruded sheet density. Thereafter, the foam sheet can be thermoformed to form a foamed article, such as a food or meat tray. The resulting article can be subjected to post-thermoforming expansion such that the resulting article has an article density that is at least 20%, at least 30%, at least 40%, and / or at least 50% less than the sheet density of the initial foam sheet. In addition, due to post-expansion, the resulting article can have an article density of no more than 0.095 g / cm 3 , not more than 0.09g / cm 3 , not more than 0.08g / cm 3 , not more than 0.07g / cm 3 , not more than 0.06g / cm 3 , not more than 0.05g / cm 3 and / or not more than 0.04g / cm 3 density. Advantageously, cellulose ester-based thermoformed articles can achieve this post-expansion without a significant amount of blowing agent remaining within the thermoformed article (or in the aforementioned foam sheet). In particular, it has been determined that the majority of the blowing agent used during the extrusion process to form the cellulose ester-based foam sheet will diffuse and / or escape from the foam sheet shortly after extrusion. For example, in some embodiments, the foam article will have less than 1 wt.%, less than 0.5 wt.%, and / or less than 0.1 wt.% of physical blowing agent within 24 hours, 12 hours, 6 hours, 2 hours, 1 hour, 30 minutes, 10 minutes, and / or 1 minute after thermoforming.

[0104] abbreviation

[0105] BA is a blowing agent; tPent is tert-pentane; IsoPent is isopentane, nPent is normal pentane; CycloPent is cyclopentane; IsoBut is isobutane; Styr is styrene; PolyStyr is polystyrene; TA is triacetin;

[0106] For example, several sample trays were formed and tested for density change and blowing agent content after thermoforming. The trays were formed from cellulose ester foam sheets extruded using a tandem extruder system. The extruded cellulose ester molten resin contained cellulose diacetate having a degree of substitution of 2.52, a melting point of 230°C-250°C, and a Tg of 189°C. The molten resin was plasticized with a loading of 15 wt.% or 20 wt.% triacetin. Talc was used as a nucleating agent and mixed into the molten resin together with a physical blowing agent in a twin-screw extruder of the tandem extruder system. The resulting molten resin was transferred to a single screw extruder where a ring die was used to extrude the cellulose ester foam sheet. The foam sheet was stretched, cut, and thermoformed to form a foam tray. A counterexample foam tray comprising polystyrene was also formed in a similar manner.

[0107] Before and after thermoforming, the sample trays were tested for density using an analytical balance. The sample is immersed in water and the volume is measured using Archimedes' principle. This method is described in DIN EN ISO 1183-1 and ISO 2781. A minimum of three samples were measured, each weighing between 1 and 5 grams. Table 4 below shows the density measurement results for the samples. While the polystyrene counterexample trays exhibited the highest post-expansion, the cellulose ester-based trays were able to achieve 60% to 80% of the polystyrene post-expansion.

[0108] Table 4.

[0109]

[0110]

[0111] In addition, liquid chromatography-mass spectrometry (LC / MS) was used to measure the residual blowing agent remaining in the sample trays after thermoforming. The gases escaping during the thermoforming process were captured using headspace gas chromatography by heating the samples to 200°C. To quantify the volatiles, the samples were dissolved in a solvent and the components were measured using LC / MS. The blowing agent used in all samples was a hydrocarbon. As shown in Table 5, it was found that the amount of dissolved hydrocarbon blowing agent in the cellulose ester-based trays was significantly lower than that in the polystyrene trays. This reduction in blowing agent may be due to the fact that hydrocarbon gases have similar solubility parameters to polystyrene and are therefore more soluble in polystyrene than cellulose esters. Therefore, foam sheets formed from polystyrene will likely need to be graded and stored for an increased amount of time after extrusion (and before thermoforming) to allow the blowing agent to fully diffuse out of the sheet. In contrast, cellulose ester-based foam sheets can be thermoformed more quickly because most of the blowing agent diffuses out immediately after the foam sheet is extruded. Additionally, because the cellulose ester-based foam sheet and / or article does not retain the blowing agent, there is a wider range of commercially relevant blowing agents that can be used to extrude the cellulose ester-based foam sheet.

[0112] Table 5.

[0113]

[0114] Some of the aforementioned benefits of cellulose ester-based foam products can be achieved through the changes in cell shape that occur after thermoforming. During the extrusion of a foam sheet using an annular die, the sheet is pulled over a mandrel, which stretches the sheet and elongates the cells. As the foam sheet cools, the cells are typically frozen in place in an elongated shape. Exposure to heat during the thermoforming process beneficially expands the cells of cellulose ester-based foam products, reproducing 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 a SEM image of a cellulose ester-based foam sheet after thermoforming. As shown in the figure, after thermoforming, the cells of the cellulose ester-based foam sheet are more rounded in shape and have a lower aspect ratio (i.e., width:height). Therefore, in some embodiments, a foam article comprising a cellulose ester is provided, wherein the foam article comprises a plurality of cells. An embodiment provides that at least 50% of the plurality of cells have a cross-sectional aspect ratio of 1:2 to 2:1. In other embodiments, at least 50% of the plurality of cells may have a cross-sectional aspect ratio 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.

[0115] In one embodiment or combination with any of the embodiments mentioned herein, the foam article, such as a pallet, can have a viscosity of less than 0.20 g / cm 3 , less than 0.18g / cm 3 , less than 0.15g / cm 3 , less than 0.12g / cm 3 , less than less than 0.10g / cm 3 , less than 0.08g / cm 3 , less than less than 0.06g / cm 3 , or less than 0.04g / cm 3 , or 0.04 to 0.8 g / cm 3 , 0.04 to 0.6 g / cm 3 , 0.04 to 0.5 g / cm 3 , 0.04 to 0.4 g / cm 3 , 0.04 to 0.3 g / cm 3 , 0.04 to 0.2 g / cm 3 , 0.04 to 0.15 g / cm 3, 0.04 to 0.12 g / cm 3 , 0.04 to 0.10 g / cm 3 , 0.04 to 0.08 g / cm 3 , 0.04 to 0.06 g / cm 3 , 0.06 to 0.8 g / cm 3 , 0.06 to 0.6 g / cm 3 , 0.06 to 0.5 g / cm 3 , 0.06 to 0.4 g / cm 3 , 0.06 to 0.3 g / cm 3 , 0.06 to 0.2 g / cm 3 , 0.06 to 0.15 g / cm 3 , 0.06 to 0.12 g / cm 3 , 0.06 to 0.10 g / cm 3 , 0.06 to 0.08 g / cm 3 , 0.08 to 0.8 g / cm 3 , 0.08 to 0.6 g / cm 3 , 0.08 to 0.5 g / cm 3 , 0.08 to 0.4 g / cm 3 , 0.08 to 0.3 g / cm 3 , 0.08 to 0.2 g / cm 3 , 0.08 to 0.15 g / cm 3 , 0.08 to 0.12 g / cm 3 , 0.08 to 0.10 g / cm 3 , 0.1 to 0.8 g / cm 3 , 0.1 to 0.6 g / cm 3 , 0.1 to 0.5 g / cm 3 , 0.1 to 0.4 g / cm 3 , 0.1 to 0.3 g / cm 3 , 0.1 to 0.2 g / cm 3 , 0.1 to 0.15 g / cm 3 , 0.1 to 0.12 g / cm 3 , 0.2 to 0.8 g / cm 3 , 0.2 to 0.6 g / cm 3 , 0.2 to 0.5 g / cm 3 , 0.2 to 0.4 g / cm 3 , 0.2 to 0.3 g / cm 3 , 0.3 to 0.6 g / cm 3 , 0.3 to 0.5 g / cm 3 , 0.3 to 0.4 g / cm3 , 0.4 to 0.6 g / cm 3 , 0.4 to 0.5 g / cm 3 , or 0.5 to 0.6 g / cm 3 density.

[0116] In one embodiment or combination with any embodiment mentioned 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, or or 300μm to 600μm, or 400μm to 600μm, or 500μm to 600μm, or 40μm to 550μm, or 40μm to 500μm, or 40μm to 450μm, or 40μm to 400μm, or 40μm to 350μm, or 40μm to 300μm, or 40μm to 250μm, or 40μm to 200μm, or 40μm to 150μm, or 40μm to 100μm.

[0117] Furthermore, it should be understood that because the foam article, such as a pallet, is formed from the cellulose esters described herein, the foam article can include any of the components and / or additives and any resulting properties of the cellulose ester-based materials described herein.

[0118] definition

[0119] It should be understood that the following is not intended to be an exhaustive list of defined terms.Other definitions may have been provided in the foregoing description, such as, for example, where context accompanies the usage of a defined term.

[0120] As used herein, the terms "a," "an," and "the" mean one or more than one.

[0121] As used herein, the terms "comprising," "comprises," and "comprise" are open transition terms used to transition from subject matter listed before the term to one or more elements listed after the term, where the one or more elements listed after the transition term are not necessarily the only elements making up the subject matter.

[0122] To be considered "compostable," a material should meet one or more of the following criteria: (1) the material is biodegradable; (2) the material is disintegrable; (3) the material does not contain heavy metals in excess of a maximum amount; and / or (4) the material is not ecotoxic.

[0123] As used herein, the term "biodegradable" generally refers to the biological transformation and consumption of organic molecules. Biodegradability is an inherent property of the material itself, and materials can exhibit varying degrees of biodegradability, depending on the specific conditions to which they are exposed. The term "disintegrable" refers to the tendency of a material to physically break down into smaller pieces when exposed to specific conditions. The degree of disintegration depends on the material itself and the physical size and configuration of the article being tested. Ecotoxicity measures the effect of a material on plant life, and the heavy metal content of a material is determined according to procedures specified in standard test methods.

[0124] According to the French standard NF T 51-800, to be considered "home compostable" under home composting conditions, a material must exhibit a total disintegration of at least 90% within 12 weeks (e.g. compared to the initial sample) measured according to ISO 16929 (2013) at ambient temperature (i.e., 28°C ± 2°C).

[0125] To be considered "industrially compostable" under industrial composting conditions according to ASTM D6400, a material must exhibit a total disintegration of at least 90% (e.g., compared to the initial sample) within 26 weeks as measured according to ISO 16929 (2013) at elevated temperature (i.e., 58°C ± 2°C).

[0126] In one embodiment or combination with any embodiment mentioned herein, the biodegradable cellulose ester foam or article (e.g., a pallet) is industrially compostable and / or home compostable. Specifically, the foam material used to make the articles described herein can be industrially compostable according to ASTM D6400 and exhibit at least 90% disintegration within twelve weeks measured at an elevated temperature of 58°C ± 2°C according to ISO 16929 (2013). Additionally or alternatively, the foam material used to make the articles described herein can be home compostable according to French standard NF T 51-800 and exhibit at least 90% disintegration within twenty-six weeks measured at an ambient temperature of 28°C ± 2°C according to ISO 16929 (2013).

[0127] In some embodiments, when formed to a thickness not exceeding (or equal to) 200 mils and a density not exceeding (or equal to) 0.2 g / cm 3 Alternatively or additionally, when formed into a foam product having a thickness not exceeding (or equal to) 400 mils and a density not exceeding (or equal to) 0.1 g / cm 3Alternatively or additionally, when formed into a foam product having a thickness not exceeding (or equal to) 800 mils and a density not exceeding (or equal to) 0.05 g / cm 3 Alternatively or additionally, when formed into a foam product having a thickness not exceeding (or equal to) 100 mils and a density not exceeding (or equal to) 0.2 g / cm 3 When the foam product is formed, the foam material can be home compostable. Alternatively or additionally, when formed to a thickness not exceeding (or equal to) 200 mils and a density not exceeding (or equal to) 0.1 g / cm 3 When the foam product is formed into a foam product, the foam material can be home compostable. Alternatively or additionally, when formed into a foam product having a thickness not exceeding (or equal to) 400 mils and a density not exceeding (or equal to) 0.05 g / cm 3 When using foam products, the foam material can be home compostable.

[0128] The composition used to prepare the biodegradable cellulose acetate foam may contain other additives such as fillers, stabilizers, odor modifiers, waxes, compatibilizers, biodegradation accelerators, dyes, pigments, colorants, lubricants, antioxidants, viscosity modifiers, antifungal agents, heat stabilizers, antibacterial agents, softeners, release agents, UV absorbers, hydrophobic additives, and combinations thereof. Each additional additive may be present in the cellulose ester-based material in an amount of less than 10 wt.%, less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, or less than 1.0 wt.%. It should be noted that the same type of compound or material may be identified for or included in multiple component classes in the cellulose acetate composition. 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 a biodegradation accelerator, for example, where a lower molecular weight PEG has a plasticizing effect, while a higher molecular weight PEG functions as a hydrophilic polymer but does not have a plasticizing effect.

[0129] In one embodiment or combination with any other embodiment mentioned herein, the foam, composition or foamable composition further comprises a photodegradation catalyst. In a class of this embodiment, the photodegradation catalyst is titanium dioxide or iron oxide. In a subclass of this class, the photodegradation catalyst is titanium dioxide. In a subclass of this class, the photodegradation catalyst is iron oxide.

[0130] In one embodiment or in combination with any other embodiment mentioned herein, the foam, composition, or foamable composition further comprises a pigment. In a class of this embodiment, the pigment is titanium dioxide, carbon black, or iron oxide. In a subclass of this class, the pigment is titanium dioxide. In a subclass of this class, the pigment is carbon black. In a subclass of this class, the pigment is iron oxide. In a subclass of this class, the pigment is a biodegradable particulate natural filler.

[0131] abbreviation

[0132] Wt is weight, wt% is weight percentage, IR is infrared; Ex is example,

[0133] Film and foam sheet production and thermoforming

[0134] One foot wide films were extruded on a 1.5" Killion extruder at the desired thickness below. Extrusion conditions were set based on polymers with PETG, Eastman cellulose acetate FT1150, and Eastman cellulose acetate FT1200 extruded between 220°C and 240°C through a coat hanger die at the desired thickness as controlled by a take-off assembly.

[0135] Foam sheet samples were made on a tandem foam production line manufactured by KraussMaffei. The extrusion line consisted of a ZE30 twin-screw extruder (as a primary extruder) and a KE60 single-screw extruder (as a secondary cooling extruder). Loss and weight feeders were used to add the formulated additives to the KE30 twin-screw feeder. A physical foaming agent was injected into the primary extruder barrel at approximately 1 / 2 to 2 / 3 of the primary extruder barrel. The material was extruded from a 50mm annular die and transported to a sizing mandrel. The annular film was then slit and turned into a flat film in the tensioning / winding station portion of the roller.

[0136] The material composition is a cellulose acetate resin (e.g., Eastman cellulose acetate CA-398-30 or FE700) with 20 wt% triacetin, 1% epoxidized soybean oil, and 0.15% doverphos S9228T, along with other minor stabilizers / odor masking agents. The material is injected with 2.6 wt% n-pentane as a blowing agent. Additional additives to the process include 1.5 wt% ABT 1000 talc and 1% chemical blowing agent (foamazol 73S). The material is extruded between 200°C and 220°C in the primary extruder and 170°C to 190°C in the secondary extruder. The line output rate is 40 kg / h. The foam produced for this testing has a density of 0.95 g / cc and an average cell size of 342 microns.

[0137] The film was placed on top of the foam and clamped in the frame of a Hydrotrim Lab thermoforming machine. The setup features top and bottom heating plates in the oven, a timer for setting the oven hold time, vacuum to pull the material through the mold, and auxiliary plugs for complex parts. The material evaluated for this study was manufactured using only vacuum, with the top and bottom plates heated to 260°C. When the part was heated for 34 seconds, the sheet temperature reached between 190°C and 205°C, as measured by an infrared thermometer.

[0138] The moisture absorption test has been described previously.

[0139] The solid skin layer can be made by any process including curing a thicker skin by controlling the evaporation rate of the blowing agent during the foaming process, placing a layer thereon by coextrusion during the foam manufacturing process. This layer can be on one side to produce an A / B (film / foam) structure or an ABA (film / foam / film) structure, etc. Additionally, the foam can be laminated in a secondary roll-to-roll process to produce the same structure, or it can be laminated in a thermoforming process. The foam parts can be made using vacuum alone or, preferably, with auxiliary plugs or matching die sets to ensure optimal part distribution, etc. The film layer can be as thin as 0.0001 to 0.05 inches (0.0025 to 1.27 mm).

[0140] Table 6. Water absorption of laminated foams.

[0141]

[0142] Table 7 shows the collapse of foams according to ISO 20200 and ISO 16929 at ambient and elevated temperatures.

[0143] Table 7. Disintegration of foam compost at elevated and ambient temperatures.

[0144]

[0145]

[0146] Foam sheet samples were made on a tandem foam production line manufactured by KraussMaffei. The extrusion line consisted of a ZE30 twin-screw extruder (as a primary extruder) and a KE60 single-screw extruder (as a secondary cooling extruder). The formulation additives were added to the KE30 twin-screw feeder using loss and weight feeders. The physical foaming agent was injected into the primary extruder barrel at approximately 1 / 2 to 2 / 3 of the primary extruder barrel. The material was extruded from a 50 mm annular die and transported to a sizing mandrel. The annular film was then slit and turned into a flat film in the tensioning / winding station portion of the roller.

[0147] Material 1 The composition was a cellulose acetate resin (Eastman Cellulose Acetate CA-398-30 or Eastman Cellulose Acetate FE700) with 20 wt% triacetin, 1% epoxidized soybean oil, and 0.15 wt% doverphos S9228T, along with other minor stabilizers / odor masking agents. The material was injected with 2.6 wt% n-pentane as a blowing agent. Other additives to the process included 1.5 wt% ABT 1000 talc and 1 wt% chemical blowing agent (foamazol 73S). The material was extruded between 200°C and 220°C in the primary extruder and 170°C to 190°C in the secondary extruder. The line output rate was 40 kg / h.

[0148] Material 2 The composition was a cellulose acetate resin (Eastman Cellulose Acetate CA-398-30 or Eastman Cellulose Acetate FE700) with 15 wt% triacetin, 1 wt% epoxidized soybean oil, and 0.15 wt% Doverphos S9228T, along with other minor stabilizers / odor masking agents. The material was injected with 2.5 wt% n-pentane as a blowing agent. Other additives to the process included 1.0 wt% ABT 1000 talc and 1 wt% chemical blowing agent (Foamazol 73S). The material was extruded between 200°C and 220°C in the primary extruder and between 180°C and 200°C in the secondary extruder. The line output rate was 40 kg / h.

[0149] Material 3The composition was a cellulose acetate resin (Eastman Cellulose Acetate CA-398-30 or Eastman Cellulose Acetate FE700) with 15 wt% triacetin, 1 wt% epoxidized soybean oil, and 0.15 wt% Doverphos S9228T, along with other minor stabilizers / odor masking agents. The material was injected with 2.3 wt% n-pentane as a blowing agent. Other additives to the process included 1.0 wt% ABT 1000 talc and 1 wt% chemical blowing agent (Foamazol 73S). The material was extruded between 200°C and 220°C in the primary extruder and 170°C to 190°C in the secondary extruder. The line output rate was 40 kg / h.

[0150] The materials were thermoformed on a Hydrotrim Lab thermoforming machine. The machine features top and bottom heating plates in the oven, a timer for setting the oven hold time, vacuum to pull the material through the mold, and auxiliary plugs for complex parts. The materials evaluated for this study were produced using only vacuum, with the top and bottom plates heated to 260°C. Sheet temperatures measured by an infrared thermometer reached between 157°C and 197°C.

[0151] Table 8.

[0152]

[0153] Table 9.

[0154]

[0155] Material 4 was 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. The material was injected with 2.6 wt% n-pentane as a blowing agent. Additional additives to the process included 1 wt% ABT 1000 talc and 1 wt% chemical blowing agent (Foamazol 73S). The material was extruded at between 200°C and 220°C in the primary extruder and at 170°C to 190°C in the secondary extruder. The production line had an output rate of 40 kg / h.

[0156] Materials (e.g., materials 1, 2, and 4) were thermoformed on a Hydrotrim Lab thermoforming machine. The device features a top and bottom heating plate in the oven, a timer for setting the hold time in the oven, a vacuum for pulling the material in the mold, and auxiliary plugs for complex parts. The materials evaluated for this study were manufactured using only vacuum, and the top and bottom plates were heated to 260°C. Sheet temperatures measured by an infrared thermometer reached between 180°C and 197°C.

[0157] Table 10.

[0158]

[0159] Table 11.

[0160]

[0161] Method Overview

[0162] Sheets of foamed cellulose acetate (Eastman cellulose acetate CA-398-30 or Eastman cellulose acetate FE700) were conditioned in a desiccator for seven days, with a small dish containing pentane replacing the desiccant to maintain a saturated atmosphere. Triplicate subsamples of 4cm x 5cm were cut from the larger sheet sample. These subsamples were placed in separate, resealable 5x 7cm polyethylene bags and quickly returned to the desiccator. The bag was kept open so as to reestablish pentane saturation. After three hours, the sample was individually tested in the following manner: the bag containing the foam was taken out from the desiccator, the bag was quickly sealed, and the weight was recorded. The foam block was then removed from its bag and placed in a small oven at 186°C ± 1.0°C for 45 seconds. Once the heating period was over, the sample was removed from the oven, quickly sealed in its original bag, and reweighed.

[0163] Experimental equipment

[0164] The baking oven used is a Pierce Reacti-Therm III heating / stirring module, which utilizes an aluminum heat block with a diameter of approximately 4.5 cm and a depth of 5 cm and an open top macroaperture. This hole is used as a heating chamber. An additional aluminum heat block is placed on each side of the heating chamber for additional thermal mass, and an approximately 3-inch x 6-inch x ¾-inch thick stainless steel sheet is placed on the top and used to seal the microchamber when heating the sample. The temperature in the heating chamber is monitored with an Amprobe TMD-56 digital thermometer and a thermocouple, which is placed in a hot well drilled into the heat block. On a Mettler ToledoXPE566 microbalance, the sample is weighed and timed with a digital laboratory timer. During the experiment, the entire baking oven apparatus is placed in a fume hood.

[0165] Thermoforming is simulated using the above method to accurately measure the maximum blowing agent retention of cellulose acetate during thermoforming conditions. The oven used in thermoforming is typically at 250 to 350°C. The oven temperature can be set to a constant or gradually increased as the sheet moves laterally through the oven. The sheet temperature prior to forming is 180 to 200°C to ensure good stretching of the sheet into the mold. The blowing agent used in manufacturing foam is typically approximately 2.3 to 3.5% hydrocarbon during extrusion, and typically half or more is lost during extrusion as the foam cools.

[0166] Table 12.

[0167]

[0168] The claims are not limited to the disclosed embodiments

[0169] The preferred forms of the present invention described above are intended to be illustrative only and should not be used in a limiting sense to interpret the scope of the present invention. Those skilled in the art may easily modify the exemplary embodiments set forth above without departing from the spirit of the present invention.

[0170] The inventors hereby declare that they intend to determine and assess the reasonable and fair scope of the invention under the doctrine of equivalents as it relates to any device that does not materially depart from the literal scope of the invention as set forth in the following claims.

Claims

1. A foam tray comprising cellulose ester and a hydrophobic cap layer formed on an outer surface of the foam tray, and wherein the tray is configured to experience a weight increase of less than 10% when subjected to a one hour water absorption test as described in the specification. 2 . The foam tray according to claim 1 , wherein the hydrophobic cap layer is formed on an outer surface of the foam tray.

3. The foam tray according to any one of claims 1 or 2, wherein the hydrophobic cap layer is formed on an upper surface of the tray.

4. The foam tray of any one of claims 1 to 3, wherein the hydrophobic cap layer is formed on a surface of the tray that forms a bowl or receiving area configured to support food items.

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

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

7. The foam tray of any one of claims 1-6, wherein the food item is one or more of: animal or plant protein, vegetables, or fruit.

8. The foam tray of any one of claims 1-7, wherein the foam tray comprises 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 with a shrink film or an overwrap film.

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

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

12. The foam tray of any one of claims 1-11, 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 of any one of claims 1-12, wherein the foam tray has a thickness of 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 of any one of claims 1-13, wherein when the foam tray is filled with water and allowed to equilibrate at room temperature for 18 hours, the foam tray has a weight increase of less than 15% according to the Water Absorption Test described in the specification.

15. The foam pallet according to any one of claims 1 to 14, wherein the foam pallet is industrially compostable according to ASTM D6400, exhibiting at least 70%, or at least 80%, or at least 90% disintegration within twelve weeks measured according to ISO 16929 (2013) at an elevated temperature of 58°C ± 2°C, and wherein the foam tray is home compostable according to French standard NF T 51-800, exhibiting at least 70%, or at least 80%, or at least 90% disintegration within twenty-six weeks measured according to ISO 16929 (2013) at an ambient temperature of 28°C ± 2°C.

16. A method of forming a foam article, the method comprising: (a) producing a foam sheet from a composition comprising a cellulose ester and having a sheet density; as well as (b) thermoforming the foam sheet to form a foam article having an article density at least 20% less than a density of the sheet.

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

18. The method according to any one of claims 16-17, wherein the density of the article is no more than 0.095 g / cm 3 , not more than 0.09g / cm 3 , not more than 0.08g / cm 3 , not more than 0.07g / cm 3 , not more than 0.06g / cm 3 , not more than 0.05g / cm 3 , and / or not more than 0.04g / cm 3 .

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

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

21. The method of claim 20, wherein the composition comprises 2-40 wt%, or 10%-30%, or 15%-20% plasticizer.

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

23. The method of any one of claims 16-22, wherein the foam article comprises one or more additional additives.

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

25. The method of any one of claims 16-24, wherein within twenty-four hours after said thermoforming, said foam article has less than 1% of said physical blowing agent.

26. The method of claim 25, wherein the foam article comprises less than 0.5% or less than 0.1% of the physical blowing agent 12 hours, 6 hours, 2 hours, 1 hour, 30 minutes, 10 minutes, or 1 minute after the thermoforming.

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