Expandable cellulose acetate compositions containing carbon dioxide and chemical blowing agents, and foams formed therefrom

Abstract

This application discloses a foamable composition comprising cellulose acetate and a combination of carbon dioxide as a physical blowing agent and a chemical blowing agent, which is used to prepare foams with lower density, smaller average foam cell size, and less corrugation than foams made with carbon dioxide alone.

Description

[Background technology]

[0001] Carbon dioxide is a commercially available blowing agent for producing extruded foam sheets. However, cellulose acetate-based foams prepared using only carbon dioxide as a physical blowing agent have an average foam cell size of approximately 350 microns and exhibit significant corrugation. Applicant has surprisingly discovered that the combination of carbon dioxide and a chemical blowing agent can reduce the average foam cell size and the occurrence of corrugation in foams prepared by extrusion. The foams also exhibit lower density compared to foams formed using carbon dioxide alone. Summary of the Invention

[0002] This application is (i) cellulose acetate, (ii) a nucleating agent; (iii) plasticizers, (iv) a physical blowing agent which is carbon dioxide, and (v) chemical foam compositions; The present invention discloses a foamable composition comprising: where: The plasticizer is present at 5-40 wt%; The nucleating agent is present at 0.1-3 wt%; The physical blowing agent is present at 0.1-5 wt%; Chemical blowing agents are present at 0.1-5 wt%; Each is based on the total weight of the composition.

[0003] The present application also discloses a foam formed from the foamable composition.

[0004] Detailed Description of the Invention The terms "a," "an," "the," and similar referents as used in the context of describing the present invention (particularly in the context of the claims below) should be construed to include both the singular and the plural unless otherwise specified herein or clearly contradicted by context. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method for referring individually to each separate value falling within the range. Unless otherwise indicated herein, each separate value is incorporated herein as if individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted otherwise by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to better elucidate the invention and does not limit the scope of the invention as otherwise claimed. No language herein should be construed as indicating any non-claimed element essential to the practice of the invention.

[0005] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limiting. Each group member may be referred to and claimed individually or in any combination with other members of that group or other elements described herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When such inclusion or deletion occurs, the specification contains the modified group and is thus deemed to embody all Markush-style group descriptions used in the appended claims.

[0006] Certain embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors anticipate that skilled artisans will employ such variations as they see fit, and the inventors intend that the invention may be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0007] Additionally, throughout this specification, numerous references are made to patents, printed publications, journal articles, and other documents ("References"). Each of the references is individually incorporated herein by reference in its entirety for the teachings referenced, to the extent that it does not contradict any specific teachings provided herein.

[0008] It should be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the invention may be utilized in accordance with the teachings herein. Accordingly, the invention is not limited to that precisely as described and illustrated.

[0009] The details set forth herein are merely for the purposes of examples of and illustrative explanations of preferred embodiments of the present invention, and are presented for the purpose of providing what is believed to be the most useful and readily understood of the principles and conceptual aspects of various embodiments of the present invention. In this regard, no attempt has been made to show structural details of the present invention beyond those necessary for a fundamental understanding of the present invention, and the description taken together with the figures and / or examples will make clear to those skilled in the art how various forms of the present invention may be embodied in practice.

[0010] It is meant and intended that the definitions and explanations used in this disclosure will prevail in any future construction unless clearly and unambiguously changed in the example(s) or unless application of the meaning would cause any construction to become meaningless or essentially meaningless. If the construction of a term causes it to become meaningless or essentially meaningless, the definition should be taken from Webster's Dictionary, 3rd Edition, or a dictionary known to those skilled in the art.

[0011] definition A blowing agent refers to a physical or chemical substance (or combination of substances) that acts to expand nucleation sites. Blowing agents can include chemical blowing agents, physical blowing agents, a combination thereof, or several types of chemical and physical blowing agents. Blowing agents can act to reduce density by forming cells at nucleation sites in the molten compound. Blowing agents can be added to the molten resin mixture, composition, or melt in the extruder, for example, by injection.

[0012] A "chemical blowing agent" is a substance that degrades, decomposes, or reacts to generate gas. Chemical blowing agents typically include a chemical foaming composition and a carrier polymer. Chemical blowing agents can be endothermic or exothermic. The chemical foaming composition in a chemical blowing agent typically degrades, decomposes, and releases gas at a specific temperature. Examples of chemical foaming compositions used in chemical blowing agents include citric acid, sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, etc.

[0013] Examples of "physical blowing agents" include N2, CO2, alkanes, alkenes, ethers, esters, ketones, argon, helium, air, water, or mixtures thereof.

[0014] Nucleating agent refers to a physical substance that provides sites for cell formation in a molten blend mixture, such as in a CE melt. As described in more detail below, the nucleating agent can be added to the blended CE material during the blending process. Alternatively, or in addition, the nucleating agent may be added during the foam sheet manufacturing process. For example, the nucleating agent can be blended with the blend introduced into the hopper of the extruder in the extrusion section. Alternatively, the nucleating agent can be added to the CE melt in the extruder itself. A physical nucleating agent is a substance that is immiscible with the polymer matrix of the CE melt at the extrusion temperature in the extrusion section. A substance that reacts (e.g., decomposes) during extrusion (e.g., at the extrusion temperature in the extruder) to form a physical nucleating agent is called a chemical nucleating agent. Therefore, a chemical nucleating agent can be considered a precursor (and referred to herein as a precursor) of a physical nucleating agent formed in situ. Nucleating agents do not include chemical nucleating agents. Therefore, a chemical nucleating agent can be considered a precursor (and referred to herein as a precursor) of a physical nucleating agent formed in situ.

[0015] Suitable physical nucleating agents (i.e., nucleating agents) include particulates having a desired particle size and / or shape to create cell nucleation sites within the CE molten resin. For example, in some embodiments, the physical nucleating agent has an average particle size of less than 1000 microns, less than 500 microns, less than 100 microns, less than 50 microns, less than 25 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 2 microns, less than 1.5 microns, and / or less than 1.0 micron. However, in some other embodiments, it may be preferable to have nanoscale-sized particles. Furthermore, in some embodiments, the physical nucleating agent preferably has a high aspect ratio (i.e., width:height). For example, in some embodiments, the physical nucleating agent has an average aspect ratio of greater than 1:1, greater than 2:1, greater than 5:1, greater than 10:1, greater than 20:1, greater than 30:1, greater than 40:1, greater than 50:1, greater than 75:1, and / or greater than 100:1. Additionally, as noted above, the physical nucleating agent must be immiscible with the polymer matrix of the CE melt resin at the extrusion temperature of the extrusion section. 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 may also be selected to have the ability to recrystallize upon cooling after melting.

[0016] Examples of suitable inorganic physical nucleating agents include, but are not limited to, minerals such as talc, CaCO3, mica, and mixtures of at least two of the foregoing. One representative example is Heritage Plastics HT6000 Linear Low Density Polyethylene (LLDPE) Based Talc Concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon oxide, titanium oxide, magnesium oxide, aluminum oxide and calcium silicate, barium sulfate, kaolin, aluminum 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 comprises an oxide, such as a metal oxide or mixed metal oxide, such as those selected from one or more of the following: aluminum oxide, antimony oxide, arsenic oxide, bismuth oxide, boron oxide, calcium oxide, gallium oxide, iron oxide, lithium oxide, magnesium oxide, silicon oxide, and titanium oxide. In other embodiments, the inorganic nucleating agent comprises a mineral. In other embodiments, the nucleating agent is selected from one or more of the following: sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, calcium carbonate, and zinc carbonate. In other embodiments, the inorganic nucleating agent comprises a silicate, such as a silicate selected from one or more of the following: magnesium silicate and calcium silicate. The inorganic nucleating agent may be in the form of a particulate.

[0017] It has been found that biodegradable natural particulate materials (e.g., organic nucleating agents) derived from renewable organic sources can also function as effective physical nucleating agents. Natural materials that can serve as physical nucleating agents include materials composed of cellulose fiber and / or cellulose starch. Examples include, but are not limited to, almond shell flour, animal fiber, apricot shell flour, bamboo flour, bark flour, seashell flour, coconut shell flour, coconut fiber, cork flour, corncob flour, corncob grit, cottonseed husks, flock and fiber, hazelnut shell flour, kenaf flour, natural fiber, nut shell husks and flour, oat fiber powder, olive stone flour, peanut husk flour, pecan shell flour, pine nut shell powder, pistachio nut shell flour, vegetable fiber, rice husk flour, rice husk grit, rice husk, soybean flour, starch powder (hydrophobic), walnut shell flour, wheat chaff, wheat husk, and wood flour. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, metallic stearates, carbon black, and dolomite.

[0018] In one embodiment, or in combination with any of the embodiments described 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 may comprise a combination or mixture of two or more different types of nucleating agents.

[0019] It should be noted that cellulose ester materials, whether in the form of compounded CE materials or CE melt resins, generally can tolerate a maximum amount of nucleating agent capable of functioning to form nucleation sites. Any remaining nucleating agent added to the cellulose ester material remains as filler. Depending on the type of filler used, fillers can provide various properties to the resulting cellulose ester foam and / or article. For example, some fillers can increase / decrease the density, ductility, Young's modulus, yield strength, heat deflection temperature, permeability, impact resistance, elongation to break, adhesive properties, biodegradation, etc. of the cellulose ester material. Fillers can also be used to change the visual (e.g., color, opacity, etc.) and tactile (e.g., material continuity, surface roughness, etc.) properties of the cellulose ester material.

[0020] cellulose acetate In embodiments, the cellulose acetate utilized in the present invention may be any known in the art that is biodegradable. Cellulose acetates that may be used in the present invention generally contain repeating units of the following structure:

[0021] [ka] In the formula, R 1 , R 2 , and R 3are independently selected from the group consisting of hydrogen and acetyl. For cellulose esters, the substitution level is usually expressed as the mean degree of substitution (DS), which is the average number of non-OH substituents per anhydroglucose unit (AGU). Conventional cellulose generally contains three hydroxyl groups per substitutable AGU unit. Therefore, DS can have a value between 0 and 3. Even after pulping and purification, natural cellulose is a large polysaccharide with a degree of polymerization between 250 and 5,000, so the assumption that the maximum DS is 3.0 is generally correct. Because DS is a statistical average, a value of 1 does not guarantee that every AGU has a single substituent. In some cases, unsubstituted anhydroglucose may exist, some with two or some with three substituents, resulting in a non-integer value. Total DS is defined as the average number of all substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to specific substituents, such as hydroxyl or acetyl. In 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.

[0022] Cellulose acetate can be produced by any method known in the art.Examples of the production process of cellulose esters are taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th Edition, Vol.5, Wiley-Interscience, New York (2004), pp.394-444.Cellulose, the starting material for producing cellulose acetate, can be obtained from various grades and sources, such as cotton linters, softwood pulp, hardwood pulp, corn fiber, and other agricultural sources, as well as bacterial cellulose, among others.

[0023] One method for producing cellulose acetate involves esterifying cellulose by mixing it with an appropriate organic acid, an acid anhydride, and a catalyst. The cellulose is then converted to a cellulose triester. A water-acid mixture is then added to the cellulose triester to effect ester hydrolysis, which can then be filtered to remove gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester may then be washed with water to remove reaction by-products, followed by dehydration and drying.

[0024] The cellulose triester that is hydrolyzed can have three acetyl substituents.These cellulose esters can be prepared by a number of methods known to those skilled in the art.For example, cellulose esters can be prepared by the heterogeneous acylation of cellulose in a mixture of carboxylic acid and anhydride in the presence of a catalyst such as H2SO4.Cellulose triester can also be prepared by the homogeneous acylation of cellulose dissolved in a suitable solvent such as LiCl / DMAc or LiCl / NMP.

[0025] Those skilled in the art will understand that the trade term cellulose triester also includes cellulose esters that are not fully acyl-substituted. 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.

[0026] After esterification of cellulose to triester, some of the acyl substituents can be removed by hydrolysis or alcoholysis to obtain secondary cellulose ester.As mentioned above, depending on the specific method used, the distribution of acyl substituents can be random or non-random.Also, secondary cellulose ester can be prepared directly without hydrolysis by using a limited amount of acylating reagent.This process is particularly useful when the reaction is carried out in a solvent that dissolves cellulose.All of these methods produce cellulose esters that are useful in the present invention.

[0027] The present application discloses a foamable composition comprising: (i) cellulose acetate; (ii) a nucleating agent; (iii) a plasticizer; (iv) a physical blowing agent, which is carbon dioxide; and (v) a chemical foam composition, wherein the plasticizer is present in an amount of 5 to 40 wt %, the nucleating agent is present in an amount of 0.1 to 3 wt %, the physical blowing agent is present in an amount of 0.1 to 5 wt %, and the chemical blowing agent is present in an amount of 0.1 to 5 wt %, each based on the total weight of the composition.

[0028] In one embodiment or in combination with any other embodiment, the foamable composition further comprises a second physical blowing agent different from the carbon dioxide physical blowing agent. In one class of this embodiment, the second physical blowing agent is N2, (C 1-6 ) alkanes, (C 2-6 ) alkenes, (C 1-6 ) alkanols, (C 1-6 )alkane-C(O)-(C 1-6 ) alkanes, or combinations thereof. In a subclass of this class, the second physical blowing agent is present in an amount of from 0.1 to 4 wt.%, based on the total weight of the composition.

[0029] In one embodiment or in combination with any other embodiment, the cellulose acetate has an average degree of substitution ("DS") of acetyl substituents of 1.8 to 2.6. Ac In one embodiment or in combination with any other embodiment, the cellulose acetate has an average degree of substitution ("DS") of acetyl substituents that is 2.2 to 2.6. Ac In one embodiment or in combination with any other embodiment, the cellulose acetate has an average degree of substitution ("DS") of acetyl substituents that is 2.1 to 2.6. Ac In one embodiment or in combination with any other embodiment, the cellulose acetate has an average degree of substitution ("DS") of acetyl substituents that is 2.1 to 2.5. Ac ").

[0030] In one embodiment or in combination with any other embodiment, the cellulose acetate exhibits a weight average molecular weight ("Mw") of greater than 50,000 daltons. In one embodiment or in combination with any other embodiment, the cellulose acetate exhibits a weight average molecular weight ("Mw") of 50,000 to 200,000 daltons. In one embodiment or in combination with any other embodiment, the cellulose acetate exhibits a weight average molecular weight ("Mw") of 50,000 to 100,000 daltons. Molecular weight can be measured according to ASTM D4674 using NMP as the solvent.

[0031] The most common commercially available secondary cellulose esters are prepared by first heterogeneously acylating cellulose with an acid catalyst to form a cellulose triester. After obtaining a homogeneous solution of the cellulose triester in the corresponding carboxylic acid, the cellulose triester is then subjected to hydrolysis until the desired degree of substitution is achieved. After isolation, random secondary cellulose esters are obtained, i.e., the relative degree of substitution (RDS) at each hydroxyl is approximately equal.

[0032] Cellulose acetate useful in the present invention can be prepared using techniques known in the art and can be selected from a wide variety of cellulose esters, such as those available from Eastman Chemical Company, Kingsport, Tenn., USA, e.g., Eastman™ Cellulose Acetate CA398-30 and Eastman™ Cellulose Acetate CA398-10.

[0033] In embodiments of the present invention, cellulose acetate can be prepared by converting cellulose to a cellulose ester using reactants obtained from recycled materials, e.g., recycled plastic-containing syngas sources. In embodiments, such reactants can be cellulose reactants including organic acids and / or acid anhydrides used in esterification or acylation reactions of cellulose, for example, as discussed herein.

[0034] 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 acetate composition comprising at least one regenerated cellulose acetate, the cellulose acetate having at least one substituent on anhydroglucose unit (AU) derived from a recycled-containing material, such as recycled plastic-containing syngas.

[0035] In one embodiment or in combination with any other embodiment, the foamable composition further comprises at least one of a filler, an additive, a biopolymer, a stabilizer, and / or an odor improver. Examples of additives include waxes, compatibilizers, biodegradation accelerators, dyes, pigments, colorants, gloss control agents, lubricants, antioxidants, viscosity modifiers, antifungal agents, antifogging agents, heat stabilizers, impact modifiers, antibacterial agents, softeners, mold release agents, and combinations thereof. It should be noted that the same type of compound or material may be identified or included in multiple categories of components 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, low molecular weight PEG has a plasticizing effect, while high molecular weight PEG functions as a hydrophilic polymer but does not have a plasticizing effect.

[0036] In one embodiment or in combination with any other embodiment, the plasticizer is a food-compatible plasticizer. In one embodiment or in combination with any other embodiment, food compatibility means compliance with applicable food additive and / or food contact regulations, where the plasticizer is permitted for use or recognized as safe by at least one (national or regional) food safety regulatory authority (or organization), for example, as listed in the 21 CFR Food Additive Regulations or generally recognized as safe (GRAS) by the US FDA.

[0037] In one embodiment or in combination with any other embodiment, the plasticizer is triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, glycol tribenzoate, or a combination thereof.

[0038] 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, acetyltriethyl citrate, polyethylene glycol, benzoic acid-containing plasticizers such as the Benzoflex™ plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, adipic acid-based plasticizers, soybean oil epoxides such as the Paraplex™ plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributyrin, sucrose acetate isobutyrate, the Resolflex™ series of plasticizers, triphenyl phosphate, glycolic acid, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diylbis(2-methylpropanoate), and polycaprolactone.

[0039] In one embodiment or in combination with any other embodiment, the plasticizer is triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, glycol tribenzoate, or a combination thereof.

[0040] In one embodiment or in combination with any other embodiment, the plasticizer is triacetin, triethyl citrate, Benzoflex, propylene glycol, polysorbate sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, glycol tribenzoate, or a combination thereof.

[0041] In one embodiment or in combination with any other embodiment, the plasticizer is triacetin.

[0042] In one embodiment or in combination with any other embodiment, the physical blowing agent is present in an amount of 0.1 to 4 wt%, or 0.1 to 3 wt%, or 0.1 to 2.5 wt%, or 0.1 to 2 wt%, or 0.1 to 1 wt%, or 0.5 to 5 wt%, or 0.5 to 4 wt%, or 0.5 to 3 wt%, or 0.5 to 2.5 wt%, or 0.5 to 2 wt%, or 0.5 to 1.5 wt%, or 0.5 to 1 wt%, or 1 to 5 wt%. t%, or 1.0-4 wt%, or 1-3 wt%, or 1-2.5 wt%, or 1-2 wt%, or 1.5-5 wt%, or 1.5-4 wt%, or 1.5-3 wt%, or 1.5-2.5 wt%, or 1.5-2 wt%, or 2-5 wt%, or 2-4 wt%, or 2-3 wt%, or 1.75-2.5 wt%, or 1.75-2.0 wt%, or less than 1.75 wt%.

[0043] In one embodiment or in combination with any other embodiment, the chemical blowing agent is biodegradable.In one embodiment or in combination with any other embodiment, the carrier polymer is biodegradable.

[0044] In one embodiment or in combination with any other embodiment, the chemical foaming composition is present at 0.1-4 wt%, or 0.1-3 wt%, or 0.1-2 wt%, or 0.1-1.5 wt%.

[0045] In one embodiment or in combination with any other embodiment, the chemical blowing agent comprises (a) a blowing agent, and (b) a carrier polymer having a melting point of 180° C. or less.

[0046] In one class of this embodiment or in combination with any other class of this embodiment, the effervescent agent comprises a bicarbonate, a carbonate, a citric acid, or a combination thereof. The bicarbonate or carbonate may be a sodium, carbonate, magnesium salt, etc. In a subclass of this class, the effervescent agent comprises sodium bicarbonate, sodium carbonate, citric acid, or a combination thereof.

[0047] In one class of this embodiment, or in combination with any other class of this embodiment, the carrier polymer comprises polybutylene succinate ("PBS"), polycaprolactone ("PCL"), polylactic acid ("PLA"), polyhydroxyalkanoate ("PHA"), polybutylene adipate terephthalate ("PBAT"), a starch derivative, poly(butylene succinate-co-butylene adipate) ("PBSA"), or a combination thereof. In a subclass of this class, the carrier polymer comprises PBS. In a subclass of this class, the carrier polymer comprises PCL. In a subclass of this class, the carrier polymer is PLA. In a subclass of this class, the carrier polymer is PHA. In a subclass of this class, the carrier polymer is PBAT. In a subclass of this class, the carrier polymer is starch. In a subclass of this class, the carrier polymer is PBSA.

[0048] In one class of this embodiment or in combination with any other class of this embodiment, the carrier polymer is present at 25-75 wt%, or 25-65 wt%, or 25-55 wt%, or 25-45 wt%, or 25-35 wt%, or 35-75 wt%, or 35-65 wt%, or 35-55 wt%, or 35-45 wt%, or 45-75 wt%, or 45-65 wt%, or 45-55 wt%, or 55-75 wt%, or 55-65 wt%, or 65-75 wt%, based on the total weight of the chemical blowing agent.

[0049] In one embodiment or in combination with any other embodiment, the foamable composition further comprises at least one stabilizer. While the foamable composition is desirably configurable and / or biodegradable, a certain amount of stabilizer may be added to provide a selected shelf life or stability, such as light exposure, oxidative stability, or hydrolytic stability. In various embodiments, the stabilizer may include UV absorbers, antioxidants (such as ascorbic acid, BHT, BHA, etc.), other acids and radical scavengers, epoxidized oils, such as epoxidized soybean oil, or combinations thereof.

[0050] Antioxidants can be divided into several classes, including primary antioxidants and secondary antioxidants. Primary antioxidants are generally known to function essentially as free radical quenchers (scavengers). Secondary antioxidants are generally known to decompose hydroperoxides (ROOH) into non-reactive products before they decompose into alkoxy and hydroxyl radicals. Secondary antioxidants are often used in combination with free radical scavengers (primary antioxidants) to achieve a synergistic inhibitory effect, and secondary AOs are used to extend the life of phenolic primary AOs.

[0051] A "primary antioxidant" is an antioxidant that acts by reacting with peroxide radicals via hydrogen transfer to quench the radical. Primary antioxidants generally contain reactive hydroxy or amino groups, such as hindered phenols and secondary aromatic amines. Examples of primary antioxidants include BHT, Irganox™ 1010, 1076, 1726, 245, 1098, 259, and 1425, Ethanox™ 310, 376, 314, and 330, Evernox™ 10, 76, 1335, 1330, 3114, MD1024, 1098, 1726, and 120. 2246, and 565, Anox™ 20, 29, 330, 70, IC-14, and 1315, Lowinox™ 520, 1790, 22IB46, 22M46, 44B25, AH25, GP45, CA22, CPL, HD98, TBM-6, and WSP, Naugard™ 431, PS48, SP, and 445, Songnox™ 1010, 1024, 1035, 1076CP, 1135LQ, 1290PW, 1330FF, 1330PW, 2590PW, and 3114FF, and ADK Stab AO-20, AO-30, AO-40, AO-50, AO-60, AO-80, and AO-330.

[0052] "Secondary antioxidants" are often called hydroperoxide decomposers. They act by reacting with hydroperoxides to break them down into non-radical, non-reactive, thermally stable products. They are often used in combination with primary antioxidants. Examples of secondary antioxidants include the organophosphorus (e.g., phosphites, phosphonites) and organosulfur classes of compounds. The phosphorus and sulfur atoms of these compounds react with peroxides, converting them to alcohols. Examples of secondary antioxidants include Ultranox 626, Ethanox™ 368, 326, and 327, Doverphos™ LPG11, LPG12, DP S-680, 4, 10, S480, S-9228, S-9228T, Evernox™ 168 and 626, Irgafos™ 126 and 168, Weston™ DPDP, DPP, EHDP, PDDP, TDP, TLP, and TPP, Mark™ CH302, CH55, TNPP, CH66, CH300, CH301, CH302, CH304, and CH305, ADK Stab 2112, HP-10, PEP-8, PEP-36, 1178, 135A, 1500, 3010, C, and TPP, Weston 439, DHOP, DPDP, DPP, DPTDP, EHDP, PDDP, PNPG, PTP, PTP, TDP, TLP, TPP, 398, 399, 430, 705, 705T, TLTTP, and TNPP, Alkanox 240, 626, 626A, 627AV, 618F, and 619F, and Songnox™ 1680FF, 1680PW, and 6280FF.

[0053] In embodiments, the foamable composition comprises at least one stabilizer, the stabilizer comprising one or more secondary antioxidants. In embodiments, the stabilizer comprises a first stabilizer component selected from one or more secondary antioxidants and a second stabilizer component selected from one or more primary antioxidants, citric acid, or a combination thereof.

[0054] In embodiments, the stabilizer comprises one or more secondary antioxidants in an amount, expressed as a weight percent of the total amount of secondary antioxidants based on the total weight of the composition, ranging from 0.01 to 0.8, or 0.01 to 0.7, or 0.01 to 0.5, or 0.01 to 0.4, or 0.01 to 0.3, or 0.01 to 0.25, or 0.01 to 0.2, or 0.05 to 0.8, or 0.05 to 0.7, or 0.05 to 0.5, or 0.05 to 0.4, or 0.05 to 0.3, or 0.05 to 0.25, or 0.05 to 0.2, or 0.08 to 0.8, or 0.08 to 0.7, or 0.08 to 0.5, or 0.08 to 0.4, or 0.08 to 0.3, or 0.08 to 0.25, or 0.08 to 0.2. In one class of this embodiment, the stabilizer comprises a secondary antioxidant that is a phosphite compound. In one class of this embodiment, the stabilizer comprises a secondary antioxidant that is a phosphite compound and another secondary antioxidant that is DLTDP.

[0055] In a subclass of this class, the stabilizer further comprises a second stabilizer component comprising one or more primary antioxidants in an amount, expressed as a weight percent of the total amount of primary antioxidants based on the total weight of the composition, ranging from 0.05 to 0.7, or 0.05 to 0.6, or 0.05 to 0.5, or 0.05 to 0.4, or 0.05 to 0.3, or 0.1 to 0.6, or 0.1 to 0.5, or 0.1 to 0.4, or 0.1 to 0.3. In a subclass of this class, the stabilizer further comprises a second stabilizer component comprising citric acid in an amount, expressed as a weight percent of the total amount of citric acid based on the total weight of the composition, ranging from 0.05 to 0.2, or 0.05 to 0.15, or 0.05 to 0.1. In a subclass of this class, the stabilizer further comprises a second stabilizer component comprising one or more primary antioxidants and citric acid in the amounts discussed herein. In a subclass of this class, the stabilizer contains less than 0.1 wt.% or no primary antioxidants, based on the total weight of the composition. In a subclass of this class, the stabilizer contains less than 0.05 wt.% or no primary antioxidants, based on the total weight of the composition.

[0056] In one embodiment or in combination with any other embodiment, the foamable composition further comprises at least one filler. In one class of this embodiment or in combination with any other class, the filler is present in a type and amount that enhances biodegradability and / or compostability. In one class of this embodiment or in combination with any other class, the foamable composition comprises at least one filler selected from the following: carbohydrates (sugars and salts), cellulose and organic fillers (wood flour, wood fiber, hemp, carbon, coal particles, graphite and starch), mineral and inorganic fillers (calcium carbonate, talc, silica, titanium dioxide, glass fiber, glass spheres, boron nitride, aluminum trihydrate, magnesium hydroxide, calcium hydroxide, alumina, and clay), food waste or by-products (eggshells, brewer's grounds, and coffee grounds), desiccants (e.g., calcium sulfate, magnesium sulfate, magnesium oxide, calcium oxide), alkaline fillers (e.g., NaCO, MgCO), or combinations (e.g., mixtures) of these fillers. In one class of this embodiment or in combination with any other class, the foamable composition may include at least one filler that also functions as a color additive. In a subclass of this class, the color additive filler may be selected from carbon, graphite, titanium dioxide, opacifiers, dyes, pigments, tints, and combinations thereof. In one class of this embodiment or in combination with any other class, the cellulose acetate composition may include at least one filler that also functions as a stabilizer or flame retardant.

[0057] In one embodiment or in combination with any other embodiment, other components that may be included in the foamable composition may function as release agents or lubricants (e.g., fatty acids, ethylene glycol distearate), antiblock or slip agents (e.g., fatty acid esters, metal stearates (e.g., zinc stearate), and waxes), antifogging agents (e.g., surfactants), heat stabilizers (e.g., epoxy stabilizers, epoxidized soybean oil (ESBO), linseed oil, and sunflower oil derivatives), antistatic agents, blowing agents, biocides, impact modifiers, or reinforcing fibers. Two or more components may be present in the foamable composition. It is noted that additional components may perform multiple functions in the foamable composition. The different (or specific) functionality of any particular additive (or component) to the foamable composition may depend on its physical properties (e.g., molecular weight, solubility, melting temperature, Tg, etc.) and / or the amount of such additive / component in the overall composition. For example, polyethylene glycol may function as a plasticizer at one molecular weight, or as a hydrophilizing agent (with little or no plasticizing effect) at another molecular weight.

[0058] In one embodiment or in combination with any other embodiment, the foamable composition further comprises 0.1 to 50 wt % of a biodegradable polymer other than cellulose acetate, based on the total weight of the foamable composition.

[0059] In one class of this embodiment or in combination with any other class of this embodiment, the biodegradable polymer is a cellulose ester other than cellulose acetate, polybutylene succinate ("PBS"), polycaprolactone ("PCL"), polylactic acid ("PLA"), polyhydroxyalkanoate ("PHA"), polybutylene adipate terephthalate ("PBAT"), a starch derivative, poly(butylene succinate-co-butylene adipate) ("PBSA"), or a combination thereof. In a subclass of this class, the biodegradable polymer is PBS, PCL, or PHA. In a subclass of this class, the biodegradable polymer is a cellulose ester other than cellulose acetate. The cellulose ester can be cellulose acetate, so long as the cellulose acetate is different from the cellulose acetate contained in the biodegradable polymer. For example, the biodegradable polymer cellulose acetate can have an average degree of substitution of less than 1.8.

[0060] The present application also discloses foams formed from the foamable compositions disclosed herein, wherein the foams are biodegradable.

[0061] In one embodiment or in combination with any other embodiment, the foam may have a viscosity of 0.2 g / cm 3 Less than or equal to 0.18 g / cm 3 Less than or equal to 0.16 g / cm 3 Less than or equal to 0.14 g / cm 3 Less than or equal to 0.13 g / cm 3 Less than or equal to 0.12 g / cm 3 Less than or equal to 0.11 g / cm 3 Less than or equal to 0.1g / cm 3 Less than or 0.1 to 0.2 g / cm 3 range, or 0.1 to 0.18 g / cm 3 range, or 0.1 to 0.16 g / cm 3 range, or 0.1 to 0.14 g / cm 3 range, or 0.1 to 0.13 g / cm 3 , or 0.1 to 0.12 g / cm 3 range, or 0.14 g / cm3 Less than or equal to 0.1g / cm 3 has a density of less than

[0062] In one embodiment or in combination with any other embodiment, the foam may be less than 400 microns, or less than 375 microns, or less than 350 microns, or less than 325 microns, or less than 300 microns, or less than 275 microns, or less than 250 microns, or less than 225 microns, or less than 200 microns, or less than 175 microns, or in the range of 250-400 microns, or in the range of 250-375 microns, or in the range of 250-350 microns, or in the range of 250-325 microns, or in the range of 250-300 microns, or in the range of 250-275 microns, or in the range of 275-400 microns, or in the range of 275-375 microns, or in the range of 275-350 microns, or in the range of 275-3 The foam has an average foam cell size in the range of 25 microns, or in the range of 275 to 300 microns, or in the range of 300 to 400 microns, or in the range of 300 to 375 microns, or in the range of 300 to 350 microns, or in the range of 180 to 350 microns, or in the range of 180 to 325 microns, or in the range of 180 to 300 microns, or in the range of 180 to 275 microns, or in the range of 180 to 250 microns, or in the range of 180 to 225 microns, or in the range of 180 to 200 microns, or in the range of 150 to 350 microns, or in the range of 150 to 325 microns, or in the range of 150 to 300 microns, or in the range of 150 to 275 microns, or in the range of 150 to 250 microns, or in the range of 150 to 200 microns.

[0063] In one embodiment or in combination with any other embodiment, the foam has a viscosity of 0.14 g / cm 3 In one embodiment or in combination with any other embodiment, the foam has a density of less than 0.14 g / cm and an average foam cell size of less than 350 microns. 3 In one embodiment or in combination with any other embodiment, the foam has a density of less than 0.1 g / cm and an average foam cell size of 180 microns to 350 microns.3 In one embodiment or in combination with any other embodiment, the foam has a density of less than 0.14 g / cm and an average foam cell size of less than 200 microns. 3 In one embodiment or in combination with any other embodiment, the foam has a density of less than 0.1 g / cm and an average foam cell size of 150 to 275 microns. 3 and the average foam cell size is less than 200 microns.

[0064] In one embodiment or in combination with any other embodiment, the foam has closed cells. In a class of this embodiment, the foam has 90% closed cells, or 80% closed cells, or 70% closed cells, or 60% closed cells, or 50% closed cells, or 40% closed cells, or 30% closed cells, or 20% closed cells, or 10% closed cells.

[0065] In one embodiment or in combination with any other embodiment, the foam has an R of less than 21 microns, or less than 20 microns, or less than 19 microns, or less than 18 microns, or less than 17 microns, or less than 16 microns, or less than 15 microns, or less than 14 microns, or between 12 and 21 microns, or between 12 and 20 microns, or between 12 and 18 microns, or between 12 and 16 microns. rms Indicates the surface area roughness.

[0066] In one embodiment or in combination with any other embodiment, the foam is in the form of a sheet.

[0067] In one embodiment or in combination with any other embodiment, the sheet has reduced corrugation compared to foamed sheets prepared using only carbon dioxide as the physical blowing agent.

[0068] In one embodiment or in combination with any other embodiment, the foam includes one or more exterior surfaces and at least one skin on one of the exterior surfaces of the foam.

[0069] In one embodiment or in combination with any other embodiment, the article is prepared from any of the foams disclosed above, and the article is biodegradable.

[0070] In one embodiment or in combination with any other embodiment, the article is industrially compostable or home compostable.

[0071] The present application also discloses a foamable composition comprising: (i) cellulose acetate; (ii) a plasticizer; (iii) a physical blowing agent that is carbon dioxide; and (iv) a chemical blowing agent, wherein the plasticizer is present in an amount of 5 to 40 wt %, the physical blowing agent is present in an amount of less than 1.75 wt %, and the chemical blowing agent is present in an amount of 0.1 to 5 wt %, each based on the total weight of the composition; and the foamable composition does not include any physical nucleating agent as an additive.

[0072] In one embodiment or in combination with any other embodiment, the foam has a viscosity of 0.14 g / cm 3 It has a density of less than 100 microns and an average foam cell size of 180 microns to 350 microns.

[0073] The present application discloses a method for preparing a foam, the method comprising: (i) forming any foamable composition disclosed herein in an extruder; and (ii) thermally expanding the foamable composition under conditions sufficient to form a foam therefrom, the conditions comprising a melt temperature of 150°C to 240°C and a thermal expansion pressure of 20 to 250 bar.

[0074] In one embodiment or in combination with any other embodiment, the melting temperature is from 150°C to 230°C, or from 150°C to 220°C, or from 150°C to 210°C, or from 150°C to 200°C, or from 150°C to 190°C, or from 150°C to 180°C, or from 150°C to 170°C, or from 150°C to 160°C, or from 160°C to 240°C, or from 160°C to 200°C, or from 160°C to 190°C, or from 160°C to 180°C, or from 160°C to 170°C, or from 170°C to 180°C. ℃ to 240℃, or 170℃ to 200℃, or 170℃ to 190℃, or 170℃ to 180℃, or 170℃ to 170℃, or 180℃ to 240℃, or 180℃ to 230℃, or 180℃ to 220℃, or 180℃ to 210℃, or 180℃ to 200℃, or 180℃ to 190℃, or 190℃ to 240℃, or 190℃ to 230℃, or 190℃ to 220℃, or 190℃ to 210℃, or 190℃ to 200℃.

[0075] In one embodiment or in combination with any other embodiment, the thermal expansion temperature is from 20 to 200 bar, or from 20 to 160 bar, or from 20 to 120 bar, or from 20 to 180 bar, or from 20 to 140 bar, or from 20 to 100 bar, or from 20 to 60 bar, or from 40 to 250 bar, or from 40 to 200 bar, or from 40 to 160 bar, or from 40 to 120 bar, or from 40 to 80 bar, or from 60 to 250 bar, or from 60 to 200 bar, or from 60 to 160 bar , or 60 to 120 bar, or 60 to 80 bar, or 80 to 250 bar, or 80 to 200 bar, or 80 to 160 bar, or 80 to 120 bar, or 100 to 250 bar, or 100 to 200 bar, or 100 to 160 bar, or 100 to 120 bar, or 120 to 250 bar, or 120 to 200 bar, or 120 to 160 bar, or 150 to 250 bar, or 150 to 200 bar, or 150 to 160 bar.

[0076] Specific Embodiments Embodiment 1. A foamable composition comprising: (i) cellulose acetate; (ii) a nucleating agent; (iii) a plasticizer; (iv) a physical blowing agent that is carbon dioxide; and (v) a chemical blowing agent; wherein the plasticizer is present at 5-40 wt.%, the nucleating agent is present at 0.1-3 wt.%, the physical blowing agent is present at 0.1-5 wt.%, and the chemical blowing agent is present at 0.1-5 wt.%, each based on the total weight of the composition.

[0077] Embodiment 2. The cellulose acetate has an average degree of substitution (DS) of acetyl substituents of 1.8 to 2.6. Ac 10. The foamable composition of claim 1, having a viscosity of 1000 psi or less.

[0078] Embodiment 3. The foamable composition of any one of Embodiments 1-2, wherein the chemical foaming agent comprises: (a) a chemical foaming composition comprising a bicarbonate, a carbonate, citric acid, or a combination thereof; and (b) a carrier polymer having a melting point of 180°C or less.

[0079] Embodiment 4. The foamable composition of embodiment 3, wherein the carrier polymer comprises polybutylene succinate ("PBS"), polycaprolactone ("PCL"), polylactic acid ("PLA"), polyhydroxyalkanoate ("PHA"), polybutylene adipate terephthalate ("PBAT"), a starch derivative, poly(butylene succinate-co-butylene adipate) ("PBSA"), or a combination thereof.

[0080] Embodiment 5. The foamable composition of any one of embodiments 1-4, wherein the plasticizer is triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, glycol tribenzoate, or a combination thereof.

[0081] Embodiment 6. The foamable composition according to any one of embodiments 1 to 5, further comprising 0.1 to 50 wt % of a biodegradable polymer other than cellulose acetate, based on the total weight of the foamable composition.

[0082] Embodiment 7. The foamable composition of embodiment 6, wherein the biodegradable polymer is a cellulose ester other than the cellulose acetate, polybutylene succinate ("PBS"), polycaprolactone ("PCL"), polylactic acid ("PLA"), polyhydroxyalkanoate ("PHA"), polybutylene adipate terephthalate ("PBAT"), a starch derivative, poly(butylene succinate-co-butylene adipate) ("PBSA"), or a combination thereof.

[0083] Embodiment 8. The foamable composition of any one of embodiments 1-7, wherein the physical blowing agent is present at less than 1.75 wt%.

[0084] Embodiment 9. The foamable composition of any one of embodiments 1 to 8, wherein the physical blowing agent is present at 1.75 to 2.5 wt %.

[0085] Embodiment 10. A foam formed from the composition of any one of embodiments 1-9, having a density of 0.2 g / cm 3 and an average foam cell size of less than 350 microns.

[0086] Embodiment 11. A foam formed from the composition of embodiment 10, having a viscosity of 0.14 g / cm 3 and an average foam cell size of 150 to 275 microns.

[0087] Embodiment 12. A foam formed from the composition of embodiment 10, having a density of 0.1 g / cm 3 and the average foam cell size is less than 200 microns.

[0088] Embodiment 13. A foamable composition comprising: (i) cellulose acetate; (ii) a plasticizer; (iii) a physical blowing agent that is carbon dioxide; and (iv) a chemical blowing agent, wherein the plasticizer is present at 5-40 wt.%, the physical blowing agent is present at less than 1.75 wt.%, and the chemical blowing agent is present at 0.1-5 wt.%, each based on the total weight of the composition; and the foamable composition does not include any physical nucleating agents as additives.

[0089] Embodiment 14. A foam formed from the foamable composition of embodiment 13, having a foam density of 0.14 g / cm 3 and an average foam cell size of 180 microns to 350 microns.

[0090] Embodiment 15. The foam of any one of embodiments 10 to 14, wherein the cells of the foam are closed.

[0091] Embodiment 16. The foam of any one of embodiments 10 to 15, in the form of a sheet.

[0092] Embodiment 17. The foam of embodiment 16, wherein the sheet exhibits reduced corrugation compared to a foam sheet prepared using only carbon dioxide as the physical blowing agent.

[0093] Embodiment 18. A foam according to any one of embodiments 10 to 17, wherein the foam comprises one or more outer surfaces and at least one skin on one of the outer surfaces of the foam.

[0094] Embodiment 19. An article prepared from the foam of any one of embodiments 10 to 18, wherein the article is biodegradable.

[0095] Embodiment 20. The article of embodiment 19, which is industrially compostable or home compostable.

[0096] Example Abbreviation CA-398-30 is Eastman cellulose diacetate CA-398-30, CBA is a chemical blowing agent, DS is the average degree of substitution, DS Ac is the average degree of substitution of the acetyl substituents, mp is the melting point, °C is degrees Celsius, PBA is a physical blowing agent, Tg is the glass transition temperature, and TA is triacetin.

[0097] Example 1 Example 1 is CA-398-30 (DS) containing TA (15 wt%). Ac = 2.52, mp = 230-250°C, Tg = 189°C).

[0098] Example 2 Example 2 is a formulation of CA-398-30 with TA (20 wt%).

[0099] Extrusion The material was extruded in a tandem line. The first extruder in the tandem line was a KraussMaffei ZE30 twin-screw extruder, and the second extruder was a KraussMaffei KE 60 single-screw extruder. The temperatures in the twin-screw zones were set at 40°C in the feed section, 200°C in the melting / mixing section, and 190°C in the conveying section and transfer pipe. Carbon dioxide blowing agent was injected into the twin-screw extruder at levels of 1%, 1.5%, and 2% by weight of the total formulation. The secondary extruder was set at 80°C in the feed section, and the remainder of the extruder was heated to 170°C and increased to 190°C in the die assembly. The formulation was extruded at 40 kg / h through an annular die onto a sizing mandrel and wound into a roll.

[0100] density The density of the extruded sheets was measured using an analytical balance in which the sample was immersed in water and the volume was 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 g.

[0101] Surface roughness The surface roughness of extruded foam sheets can be analyzed using a Bruker ContourGT optical profilometer. Surface roughness data can be measured at three spots on one side of the sheet. A 0.55x objective lens can be used, and root mean square (RMS) values ​​can be obtained.

[0102] result Several foam samples were prepared with and without CBA. The foams and physical properties are shown in Table 1. Foams prepared with PBA had a viscosity of 0.133-0.197 g / cm 3 and average foam cell size was 363-637 microns. On the other hand, foams prepared with PBA and CBA showed improved density and average foam cell size, with a density range of 0.101-0.142 g / cm. 3 The average foam cell size was 269 to 327 microns.

[0103] [Table 1] Table 2 provides additional results.

[0104] [Table 2]

Claims

1. (i) cellulose acetate, (ii) a nucleating agent; (iii) a plasticizer; (iv) a physical blowing agent which is carbon dioxide, and (v) chemical blowing agents; A foamable composition comprising: based on the total weight of the composition the plasticizer is present at 5 to 40 wt %; the nucleating agent is present at 0.1 to 3 wt %; the physical blowing agent is present at 0.1 to 5 wt %; the chemical blowing agent is present at 0.1 to 5 wt %; The foamable composition.

2. The cellulose acetate has an average degree of substitution ("DS") of acetyl substituents of 1.8 to 2.

6. Ａｃ 10. The foamable composition of claim 1, wherein

3. The chemical foaming agent is (a) a chemical foaming composition comprising a bicarbonate, a carbonate, citric acid, or a combination thereof; (b) a carrier polymer having a melting point of 180°C or less; The foamable composition according to any one of claims 1 to 2, comprising:

4. 4. The foamable composition of claim 3, wherein the carrier polymer comprises polybutylene succinate ("PBS"), polycaprolactone ("PCL"), polylactic acid ("PLA"), polyhydroxyalkanoate ("PHA"), polybutylene adipate terephthalate ("PBAT"), a starch derivative, poly(butylene succinate-co-butylene adipate) ("PBSA"), or a combination thereof.

5. 5. The foamable composition of any one of claims 1 to 4, wherein the plasticizer is triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, glycol tribenzoate, or a combination thereof.

6. The foamable composition according to any one of claims 1 to 5, further comprising 0.1 to 50 wt% of a biodegradable polymer other than cellulose acetate, based on the total weight of the foamable composition.

7. 7. The foamable composition of claim 6, wherein the biodegradable polymer is a cellulose ester other than the cellulose acetate, polybutylene succinate ("PBS"), polycaprolactone ("PCL"), polylactic acid ("PLA"), polyhydroxyalkanoate ("PHA"), polybutylene adipate terephthalate ("PBAT"), a starch derivative, poly(butylene succinate-co-butylene adipate) ("PBSA"), or a combination thereof.

8. 8. The foamable composition of any one of claims 1 to 7, wherein the physical blowing agent is present at less than 1.75 wt%.

9. 9. The foamable composition of any one of claims 1 to 8, wherein the physical blowing agent is present at 1.75 to 2.5 wt%.

10. 10. A foam formed from the composition of any one of claims 1 to 9, having a viscosity of 0.2 g / cm ３ and an average foam cell size of less than 350 microns.

11. 11. A foam formed from the composition of claim 10 having a viscosity of 0.14 g / cm ３ and an average foam cell size of 150 to 275 microns.

12. 11. A foam formed from the composition of claim 10, having a viscosity of 0.1 g / cm ３ and the average foam cell size is less than 200 microns.

13. (i) cellulose acetate, (ii) a plasticizer; (iii) a physical blowing agent which is carbon dioxide, and (iv) chemical blowing agents; A foamable composition comprising: based on the total weight of the composition the plasticizer is present at 5 to 40 wt %; the physical blowing agent is present at less than 1.75 wt %; the chemical blowing agent is present at 0.1 to 5 wt %; The foamable composition does not include any physical nucleating agent as an additive.

14. 14. A foam formed from the foamable composition of claim 13, having a viscosity of 0.14 g / cm ３ and an average foam cell size of 180 microns to 350 microns.

15. The foam of any one of claims 10 to 14, wherein the cells of the foam are closed.

16. The foam of any one of claims 10 to 15 in the form of a sheet.

17. 17. The foam of claim 16, wherein the sheet exhibits reduced corrugation compared to a foamed sheet prepared using only carbon dioxide as a physical blowing agent.

18. 18. The foam of any one of claims 10 to 17, wherein the foam comprises one or more outer surfaces and at least one skin on one of the outer surfaces of the foam.

19. An article prepared from the foam of any one of claims 10 to 18, said article being biodegradable.

20. 20. The article of claim 19, which is industrially compostable or home compostable.

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