Shaping mandrels and liquid recovery methods for use in sheet production processes

Abstract

A mandrel for use in a foam sheet production process. The mandrel may include features for controlling the surface temperature of the mandrel and / or for collecting liquid condensate formed during the foam sheet production process. The mandrel may be used in conjunction with systems and methods for recovering and optionally reusing liquid condensate. The mandrels, systems, and methods are particularly useful for recovering plasticizer components in the production of cellulose ester foam sheets and articles.

Description

BACKGROUND

[0001] Many foamed articles, such as food packaging articles, are disposable items that are intended to be disposed of after use. One commercially important material for making foamed articles 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. Thus, it is desirable to find alternative materials for foamed articles as well as viable compositions, methods, and systems for producing such articles.

[0002] Additionally, during conventional foamed sheet production processes, an amount of useful liquid condensate is produced. Existing processes and systems typically dispose of such liquids. For example, liquids that drip from the system can be collected in a drain for treatment and disposal. Thus, it is desirable to find alternative systems and methods for recycling these liquids for subsequent use. SUMMARY

[0003] In one embodiment or in combination with any other embodiment mentioned herein, a foamed sheet forming method is provided. The method includes: (a) extruding a composition through an annular die to form a tubular extrudate; and (b) drawing the tubular extrudate over a surface of a forming mandrel. The surface of the forming mandrel is maintained at a temperature above 30 °C.

[0004] In another embodiment or in combination with any other embodiment mentioned herein, a method for recycling liquids formed during a foamed sheet forming process is provided. The method includes: (a) extruding a composition through an annular die to form a tubular extrudate; (b) drawing the tubular extrudate over a forming mandrel, the mandrel including an outer surface having one or more liquid collection features formed therein; (c) cooling the tubular extrudate, thereby producing a foamed extrudate and a liquid condensate; and (d) directing at least a portion of the liquid condensate through the one or more liquid collection features into a liquid recycling system.

[0005] In another embodiment or in combination with any other embodiment mentioned herein, a method for recycling liquids formed during a foamed sheet forming process is provided. The method includes: (a) extruding a composition through an annular die to form a tubular extrudate; (b) drawing the tubular extrudate over a forming mandrel, the mandrel including an elongated axis that is inclined; (c) cooling the tubular extrudate, thereby producing a foamed extrudate and a liquid condensate; and (d) directing at least a portion of the condensate into a liquid recycling system. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1is a schematic illustration of a biodegradable article forming process according to embodiments of the application;

[0007] Figure 2 is a schematic illustration of another biodegradable article forming process according to embodiments of the application;

[0008] Figure 3 is a schematic illustration of an extrusion section of an article forming process according to embodiments of the application that can be used in the formation of Figure 1 and / or Figure 2 ;

[0009] Figure 4 is a schematic illustration of another extrusion section of an article forming process according to embodiments of the application that can be used in the formation of Figure 1 and Figure 2 ;

[0010] Figure 5 is a schematic illustration of a sheet forming section of an article forming process according to embodiments of the application that can be used in the formation of Figure 1 and / or Figure 2 ;

[0011] Figure 6 is a schematic illustration of an exemplary forming mandrel including heat transfer conduits adjacent to the surface of the mandrel according to embodiments of the application;

[0012] Figure 7 is a schematic illustration of exemplary extrusion sections and sheet forming sections having associated liquid collection systems according to embodiments of the application;

[0013] Figure 8 is a schematic illustration of an exemplary liquid collection system according to embodiments of the application;

[0014] Figure 9 is a schematic illustration of a tilted mandrel according to embodiments of the application;

[0015] Figure 10 is a schematic illustration of a mandrel including liquid collection channels according to embodiments of the application; and

[0016] Figure 11 is a schematic illustration of a mandrel including liquid collection openings according to embodiments of the application. DETAILED DESCRIPTION

[0017] Embodiments generally relate to methods, systems, and compositions for forming biodegradable granular materials (e.g., pellets), foam sheets, and articles. In certain embodiments, the forming mandrels described herein have several advantages over conventional mandrels used in foam sheet forming processes. Some embodiments described herein advantageously enable the recovery and, optionally, reuse of liquid components produced during material processing. Exemplary methods including the methods, systems, and compositions are depicted in Figures 1 to 11 and described in more detail below.

[0018] Methods and systems

[0019] 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.

[0020] 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.

[0021] The compounding process can include a granulation process. The granulation process can generally include mixing the biodegradable polymer material, plasticizer, and one or more other additives to form a mixed composition, and forming a granular material from the composition. In particular, the granulation process can include a pelletization process, and the granular material can include an amount of pellets. The term "compounded CE material" means a cellulose ester material formed in a compounding process, which can include a mixture of cellulose ester, plasticizer, and other additives. Further, such compounded CE material can be in the form of a granular material or pellets. It will be understood that, as used herein, the phrase "granulation" or "granulation process" can be the same as, or can at least include, "pelletization" or "pelletization process." In some embodiments, the granulation process can include pelletization into a water bath, pelletization on an air cooling belt, underwater pelletization, solvent compounding, etc.

[0022] 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 involving combining the cellulose ester with the plasticizer and optionally other additives in a twin-screw extruder with appropriate mixing elements at appropriate temperatures and pressures to obtain a molten homogeneous combined cellulose ester mixture as the material exits the extruder. The molten compounded cellulose ester mixture can then be extruded through a die having orifices of about 2 mm to 6 mm in diameter in order to extrude a strand. This strand can then be cooled by water (e.g., by underwater pelletization) or air, and cut at regular intervals to provide uniform and desired size and shape, referred to as "pellets" or "granules." Although methods for forming pelletized compounded materials are described herein, it will be understood that, in accordance with some embodiments, the compounded material fed to the foam sheet production process can be in any physical shape (e.g., pellets, powder, granules, fibers). The term "compounded CE material" means a cellulose ester material formed in a compounding process, which can include a mixture of cellulose ester, plasticizer, and other additives. Further, such compounded CE material can be in the form of a molten mixture or a granular material (e.g., pellets, powder, granules, fibers, etc.).

[0023] As Figure 1 and Figure 2 Compounded CE material, which can include pellets of plasticized biodegradable polymer as described above, can then be introduced into a foam sheet production process. The foam sheet production process can include one or more zones / steps for producing a foam sheet or film, which will be described in more detail below. Although exemplary foam sheet production processes are described herein, it will be understood that certain aspects described herein can also be applicable to rigid (i.e., non-foam) materials and articles. As 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. 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 modifying additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0024] The foam sheet production process can generally include an extrusion section and a sheet forming section. Figure 3 An exemplary extrusion section is depicted. As shown, the extrusion section can include a feed preparation zone, where solid additives can be combined with the compounded CE material and introduced to a downstream extrusion zone. In one embodiment or in combination with any other embodiment mentioned herein, the feed preparation zone can include a feed hopper. Thus, the compounded CE material and other solid additives can be placed into the feed hopper, which introduces the combined feed composition into the extrusion zone. The feed preparation zone can also include a mixer, where the compounded CE material and one or more additives can be mixed prior to introduction into the hopper. Mixing can be accomplished by any known mixing technique, including but not limited to tumbling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling. One or more exemplary solid additives that can be combined with the compounded material can include one or more chemical blowing agents, one or more nucleating agents, one or more surface modifying additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0025] The combined feed composition from the feed preparation zone can then be introduced to an extrusion zone. The extrusion zone can generally 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 an 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 through the extruder barrel toward the die, the composition can be heated and at least partially melted. Thus, the term "CE melt composition" as used herein means a cellulose ester-based feed composition that has been melted into a flowable molten resin by the extrusion section. Heating can be supplied by external heaters positioned along the outside of the extruder barrel. The shape of the extrudate will generally depend on the shape and size of the die head. As described below, the extrudate can be further shaped by downstream processes.

[0026] One or more additives can be introduced into the CE melt composition while the CE melt composition is in the extruder. For example, one or more physical blowing agents can be added to the composition by injecting the physical blowing agents into the CE melt composition being conveyed within the extruder barrel.

[0027] As Figure 4 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 unitary apparatus. Regardless, the feed composition from the feed preparation zone is introduced into the primary extrusion vessel and, as described above, at least partially melted as it is conveyed through the extruder barrel, producing a CE melt composition. The CE melt composition exiting the primary extrusion vessel can have a temperature of about 220 °C to about 240 °C. As the CE melt composition is conveyed through the primary extrusion vessel, one or more additives, such as a blowing agent, can be added to the CE melt composition.

[0028] The CE melt composition from the primary extrusion vessel is then introduced into the cooling vessel. The cooling vessel can 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 melt composition can be further mixed to provide a substantially uniform mixture of the melted polymer and other additives. The CE melt composition can then be directed through a die and out of the die head to provide a cellulose ester-based extrudate that can be further processed in the sheet forming section of the foam sheet production process. In one embodiment or in combination with any other embodiment mentioned herein, the CE melt composition exiting the die head can 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.

[0029] As Figure 4 depicted, one or more filtration devices can be installed within the extrusion section to filter and remove particulate matter from the CE melt composition. For example, a screen changer filtration device can be installed at the downstream end of the primary extrusion vessel and the secondary extrusion vessel, which can remove solid components from the CE melt composition before the CE melt composition is directed through the die head to the sheet forming section.

[0030] The sheet forming section can include any of a variety of systems and processes for shaping the extrudate into a sheet of cellulosic ester material that can be used for article formation. The shape of the extrudate will generally depend on the shape of the die head, while 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 subjected to further processing to form a flat sheet. In embodiments where the die has an annular shape, the die can have a diameter of 1 cm to 40 cm, 2 cm to 20 cm, 2 cm to 10 cm, and / or 3 cm to 8 cm. Further, the thickness of the opening through which the extrudate is discharged (referred to herein as the "die gap") can generally be 0.1 mm to 6.0 mm, 0.1 mm to 3.0 mm, and / or 0.1 mm to 1.0 mm.

[0031] Figure 5 An exemplary sheet forming section is depicted. As shown, the CE melt composition is extruded through an annular die and drawn over a forming mandrel. Cooling fluid (e.g., air) can be flowed through the interior and / or exterior of the extrudate to cool the extrudate material as it passes over the mandrel. For example, cooling fluid can be blown from the mandrel toward the die to cool the interior surface of the extrudate between the die and the mandrel. Additionally or alternatively, cooling fluid can be flowed through the mandrel to cool the exterior surface of the extrudate as it passes over the mandrel. In some embodiments, the tubular extrudate is cooled by a cooling ring positioned around the mandrel. In certain embodiments, the cooling ring is positioned at a distance of at least 1 foot, at least 2 feet, or at least 3 feet from the annular die. A heated gaseous (vapor) stream (e.g., air) can be fed through the interior portion of the mandrel, for example, to ensure that the extrudate remains sufficiently aerated so that it can be continuously drawn over the mandrel, as Figure 6 depicted. In some embodiments, the heated vapor stream can comprise air, nitrogen, or carbon dioxide, although other gaseous components can also be used.

[0032] In one embodiment, or in combination with any other embodiment mentioned herein, the extrudate is drawn over an outer surface of the forming mandrel, which is maintained at a temperature above 30 °C. The surface can be maintained at a temperature of at least 40 °C, at least 50 °C, or at least 60 °C. In some embodiments, the temperature can be controlled by providing heat from one or more electric heating elements positioned at least partially adjacent to the surface. For example, one or more heating elements and / or one or more insulating elements can be positioned at least partially around the space between the annular die and / or the forming mandrel. In some embodiments, the one or more heating elements comprise infrared (IR) heaters. Additionally or alternatively, the temperature can be controlled by flowing a heat transfer medium (heat transfer fluid) through a conduit positioned at least partially adjacent to the surface so as to provide indirect heat transfer between the heat transfer medium and the surface.

[0033] Figure 6 An exemplary forming mandrel is shown that includes a heat transfer conduit adjacent to the surface of the mandrel. In operation, a heat transfer medium can be introduced into the conduit and flow through the conduit that encircles the inside of the surface of the mandrel. The temperature of the heat transfer medium introduced into the conduit can be adjusted as needed to maintain a desired surface temperature of the mandrel. Exemplary heat transfer fluids can include air, water, oil, glycols, and mixtures thereof, although it will be appreciated that other suitable heat transfer fluids can also be used.

[0034] The length of the forming mandrel is generally dependent on the elasticity of the extrudate, which in turn is dependent on a variety of factors, such as composition, temperature, and the like, as described herein. In particular, the selected blowing agent can have a significant impact on the appropriate length of the forming mandrel. For example, compositions that include CO2 as a blowing agent can require a shorter forming mandrel than compositions that include larger hydrocarbon blowing agents. Without being bound by any theory, it is believed that the internal pressure from the blowing agent causes the extrudate not to shrink in the transverse direction. Because CO2 diffuses from the extrudate more quickly than hydrocarbons (e.g., pentane), the extrudate will freeze (shrink) if drawn over a mandrel of a length that is too long. In one embodiment, or in combination with any other embodiment mentioned herein, the forming mandrel has a length of 2 feet to 30 feet, 3 feet to 20 feet, 4 feet to 15 feet, or 5 feet to 10 feet. In some embodiments, and particularly when CO2 is included as a blowing agent, the forming mandrel can have a length of 2 feet to 5 feet.

[0035] The forming mandrel can be made of a variety of materials, and its parts can be made of the same or different materials. However, the material used for the outer surface of the forming mandrel (i.e., the surface over which the extrudate is drawn) can have important process consequences. For example, the material of the surface can be selected to avoid corrosion, pitting, etching, etc. by certain components in the extrudate composition, such as acids (e.g., acetic acid), to provide desirable heat transfer characteristics, and / or to have a desirable coefficient of friction with the extrudate composition. In some embodiments, the surface can comprise aluminum and / or stainless steel. In some embodiments, the surface can comprise a protective coating. Exemplary protective coatings can include carbon coatings, Teflon coatings, and chromium coatings. Notably, chromium coatings have traditionally been avoided in forming mandrels because they can react with styrene in traditional foam sheet composition. However, because the compositions described herein are typically cellulose ester compositions (rather than polystyrene), such reactions are not a problem. Additionally or alternatively, materials and coatings that provide a generally smooth surface (rather than a matte surface) can be preferred in order to be able to more easily draw the extrudate over the mandrel without rupturing the material.

[0036] Referring again to Figure 5 The tubular extrudate can be opened using a slitter (or slitting device), which allows the tubular shape to be formed into a flat sheet. For example, the tubular extrudate that has passed over the mandrel can be slit and drawn to a tensioning station that includes one or more rollers that flatten the extrudate and maintain the necessary amount of tension on the extrudate to continue pulling the extrudate off of 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 up for packaging and shipping.

[0037] Referring again to Figure 1 and Figure 2 The sheet produced by the sheet production process can be used to form a foam article, which will be described in more detail below. Such articles are particularly useful in the food service industry. Exemplary articles include meat trays. The articles can have one or more particularly advantageous properties. For example, the articles can be biodegradable and / or compostable, and / or the articles can have excellent mechanical properties (e.g., strength, density, cell size, absorbency, etc.).

[0038] During one or more of the operations described above, an amount of valuable liquid can be released from the CE material being processed. For example, valuable plasticizer in the extrudate can separate and form a liquid condensate on the extrudate. In one embodiment, or in combination with any other embodiment mentioned herein, at least a portion of the liquid condensate can be recovered for further use.

[0039] Referring now to Figure 7illustrating a sheet forming process that can include any one or more of the operations described above with respect to Figures 1 to 5 and a system for recovering liquids produced during such operations.

[0040] As Figure 7 illustrated, biodegradable polymeric materials can be introduced into a compounding process as described above to form a particulate feed composition to an extrusion section. In one embodiment or in combination with any other embodiment mentioned herein, the particulate composition can be dried to produce a dried particulate material prior to being introduced to the extrusion section (e.g., via a feed zone hopper). The (optionally dried) particulate material is then melted and extruded in an extrusion zone.

[0041] The extrudate from the extrusion process is then processed in a sheet forming section, such as described herein. For example, as Figure 5 and Figure 8 illustrated, the molten composition can be extruded through an annular die, and the tubular extrudate is drawn over a forming mandrel, whereby the extrudate begins to cool. The tubular extrudate can be slit (e.g., via a slitter or a slitter knife) and wound into a sheet. During one or more of these processes, liquid condensate can form on the extrudate, which can be recovered in a liquid collection system and used elsewhere in the sheet forming process.

[0042] Reference is now made to Figures 8 to 11 illustrating an exemplary liquid collection system. It should be understood that the liquid collection system can include features illustrated in Figures 8 to 11 and described individually herein or in combination with one or more other features. As Figure 8 illustrated, in one embodiment or in combination with any other embodiment mentioned herein, the liquid collection system can include a spout that can be positioned downstream of the mandrel and operable to collect liquid condensate formed on the mandrel and / or extrudate. The collected liquid can contain plasticizer and can be combined with other condensed liquids recovered and / or recycled into upstream processes in which the plasticizer is introduced, as described herein.

[0043] Generally, the forming mandrel can be elongated in the direction of travel of the extrudate being drawn over the mandrel. As Figure 9As shown in one embodiment or in combination with any other embodiment mentioned herein, the forming mandrel can be positioned within the sheet forming section so as to have a tilted elongated axis. For example, the forming mandrel can include a first end positioned proximal to the annular die and having a first height, and a second end positioned distal to the annular die and having a second height, where the first height is higher than the second height. The tilted elongated axis allows gravity to direct liquid condensate formed on the extrudate or collected in the mandrel toward a spout or other liquid collection device at one end of the mandrel.

[0044] As shown in one embodiment or in combination with any other embodiment mentioned herein, the forming mandrel can include one or more liquid collection features. For example, as shown in Figure 10 Figure 11 As shown in one embodiment or in combination with any other embodiment mentioned herein, the forming mandrel can include one or more liquid collection features. For example, as shown in Figure 10 During operation, at least a portion of the liquid condensate formed on the extrudate or the mandrel can collect in the one or more channels and flow through the channels toward a liquid recovery system (e.g., a spout). Additionally or alternatively, as shown in Figure 11 During operation, at least a portion of the liquid condensate formed on the extrudate or the mandrel can collect in the one or more channels and flow through the channels toward a liquid recovery system (e.g., a spout). Additionally or alternatively, as shown in

[0045] In one embodiment or in combination with any other embodiment mentioned herein, the liquid recovery system can include a conduit (e.g., a hose, a pipe, etc.) at least partially disposed within the mandrel and operable to collect the liquid condensate and direct the condensate out of the mandrel. A suction pump can be used to remove the liquid condensate from the mandrel through the conduit.

[0046] The liquid condensate removed from the mandrel can then be recovered into a liquid collection system. The liquid can be filtered in the liquid recovery system to remove solids of various sizes (e.g., particulates, foam fragments, dust, and other contaminants). At least a portion of the liquid condensate can then be reused in one or more upstream processes in which a liquid component (e.g., a plasticizer) is introduced, as described herein.

[0047] Compositions

[0048] ​The above methods can include preparing and extruding compositions that can be used in downstream processing to form useful articles. For example, in one embodiment or in combination with any other embodiment mentioned herein, the extrusion feed can comprise a particulate material comprising a biodegradable polymer, a plasticizer, and optionally one or more additives, such as those described herein. In one embodiment or in combination with any other embodiment mentioned herein, the feed material can be combined with one or more additives, such as those described herein, to provide a mixed composition comprising a biodegradable polymer, a plasticizer, and one or more additives. In one embodiment or in combination with any other embodiment mentioned herein, the biodegradable polymer comprises a cellulose ester. Additional details of the composition components, including the biodegradable polymer (e.g., cellulose ester), plasticizer, and other additives are provided below.

[0049] Cellulose ester

[0050] The cellulose ester used as described herein can be any known in the art. Cellulose esters useful in embodiments herein generally comprise repeating units of the following structure:

[0051]

[0052] wherein R1, R2, and R3 are independently selected from hydrogen, acetyl, propyl, or butyl. The level of substitution of a cellulose ester is generally expressed in terms of a degree of substitution (DS), which is the average number of non-OH substituents per anhydroglucose unit (AGU). Typically, conventional cellulose contains three hydroxyl groups per AGU unit that can be substituted; thus, the value of the DS can be between zero and three. Native cellulose is a large polysaccharide with a degree of polymerization of 250-5,000 even after pulping and purification, and thus the assumption of a maximum DS of 3.0 is approximately correct. Since the DS is a statistical average, a value of 1 does not guarantee a single substituent per AGU. In some cases, there can be unsubstituted anhydroglucose units, some with two substituents and some with three substituents, and typically the value will be a non-integer. The overall DS is defined as the average number of all substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to a particular substituent, such as, for example, a hydroxyl or acetyl group. In one embodiment or in combination with any other embodiment, n is an integer in the range of 25 to 250, or 25 to 200, or 25 to 150, or 25 to 100, or 25 to 75.

[0053] 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 / gram, or about 0.5 to about 1.8, or about 1 to about 1.5, measured at a temperature of 25 °C for a 0.25 gram sample in 100 ml of a 60 / 40 weight solution of phenol / tetrachloroethane. 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 substituent ester is acetyl.

[0054] The cellulose ester 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 in different grades and sources, such as from cotton linters, softwood pulp, hardwood pulp, corn fiber and other agricultural sources, as well as bacterial cellulose, etc.

[0055] One method of producing cellulose esters is by esterification of cellulose by mixing cellulose with an appropriate organic acid, acid anhydride, and catalyst. The cellulose is then converted to a cellulose triester. Ester hydrolysis is then performed by adding a water-acid mixture to the cellulose triester, which can then be filtered to remove any gelled particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester can then be washed with water to remove reaction byproducts, followed by dewatering and drying.

[0056] The cellulose triesters to be hydrolyzed can have three acetyl substituents. These cellulose esters can be prepared by a number of methods known to those skilled in the art. For example, cellulose esters can be prepared by heterogeneous acylation of cellulose in a mixture of carboxylic acid and acid anhydride in the presence of a catalyst such as H2SO4. 4) Cellulose triesters can also be prepared by homogeneous acylation of cellulose dissolved in an appropriate solvent such as LiCl / DMAc or LiCl / NMP.

[0057] Those skilled in the art will appreciate that the commercial term cellulose triester also encompasses cellulose esters that are not completely substituted with acyl groups. For example, cellulose triacetate, which is commercially available from Eastman Chemical Company, Kingsport, TN, U.S.A., typically has a DS of about 2.85 to about 2.99.

[0058] After esterification of the cellulose to the triester, the acyl substituents can be removed, either by hydrolysis or alcoholysis, to give a secondary cellulose ester. As previously mentioned, depending on the particular method employed, the distribution of acyl substituents can be random or non-random. Secondary cellulose esters can also be prepared directly, without hydrolysis, by using a limited amount of acylating reagent. This method is particularly useful when the reaction is carried out in a solvent that dissolves the cellulose. All of these methods result in cellulose esters that can be used in the present application.

[0059] In one embodiment or in combination with any of the mentioned 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 solvent and polystyrene equivalent according to ASTM D6474. In one embodiment or in combination with any other embodiment, the cellulose acetate composition comprises cellulose diacetate having a polystyrene equivalent number average molecular weight (Mn) of 10,000 to 90,000; or 10,000 to 80,000; or 10,000 to 70,000; or 10,000 to 60,000; or 10,000 to less than 60,000; or 10,000 to less than 55,000; or 10,000 to 50,000; or 10,000 to less than 50,000; or 10,000 to less than 45,000; or 10,000 to 40,000; or 10,000 to 30,000; or 20,000 to less than 60,000; or 20,000 to less than 55,000; or 20,000 to 50,000; or 20,000 to less than 50,000; or 20,000 to less than 45,000; or 20,000 to 40,000; or 20,000 to 35,000; or 20,000 to 30,000; or 30,000 to less than 60,000; or 30,000 to less than 55,000; or 30,000 to 50,000; or 30,000 to less than 50,000; or 30,000 to less than 45,000; or 30,000 to 40,000; or 30,000 to 35,000; as measured by gel permeation chromatography (GPC) using NMP as solvent and polystyrene equivalent according to ASTM D6474.

[0060] The most common commercial secondary cellulose esters are prepared by an initial acid-catalyzed heterogeneous acylation of cellulose 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 obtained. Upon isolation, a random secondary cellulose ester is obtained. That is, the relative degree of substitution (RDS) of each hydroxyl group is approximately equal.

[0061] Cellulose esters useful in the present application 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, U.S.A., for example, Eastman Cellulose Acetate CA 398-30 and Eastman Cellulose Acetate CA 398-10. TM Cellulose Acetate CA 398-30 and Eastman Cellulose Acetate CA 398-10. TM Cellulose Acetate CA 398-30 and Eastman Cellulose Acetate CA 398-10. TM Cellulose Propionate CAP 485-20; Eastman Cellulose Butyrate CAB 381-2. TM Cellulose Propionate CAP 485-20; Eastman Cellulose Butyrate CAB 381-2.

[0062] In one embodiment or in combination with any other embodiment, the cellulose ester can be prepared by converting cellulose to a cellulose ester with a reactant obtained from a recycled material (e.g., a recycled plastic content syngas source). In one embodiment or in combination with any other embodiment, such a reactant can be a cellulose reactant, which includes an organic acid and / or an acid anhydride used in an esterification or acylation reaction of cellulose, for example, as discussed herein.

[0063] In one embodiment of the present application 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 a anhydroglucose unit (AU) derived from a recycled content material (e.g., a recycled plastic content syngas).

[0064] In one embodiment or in combination with any other embodiment, the amount of cellulose ester included in the cellulose ester composition is 50 wt% to 99 wt%, or 60 wt% to 99 wt%, or 70 wt% to 99 wt%, or 80 wt% to 99 wt%, or 50 wt% to 98 wt%, or 60 wt% to 98 wt%, or 70 wt% to 98 wt%, or 80 wt% to 98 wt%, or 90 wt% to 98 wt%, or 50 wt% to 90 wt%, or 60 wt% to 90 wt%, or 70 wt% to 90 wt%, or 80 wt% to 90 wt%, or 90 wt% to 99 wt%, or 50 wt% to 80 wt%, or 60 wt% to 80 wt%, or 70 wt% to 80 wt%, or 50 wt% to 70 wt%, or 60 wt% to 70 wt%, or 50 wt% to 60 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein can comprise a combination, blend, or mixture of two or more different types of cellulose ester. For example, in some embodiments, the cellulose ester used herein can be comprised of a blend of two or cellulose esters having different DSAC; however, the blend can have a total DSAC between 2.2 and 2.8.

[0065] Plasticizer

[0066] In one embodiment or in combination with any other embodiment, the cellulose ester composition described herein can include at least one plasticizer. Plasticizers lower the melting temperature (i.e., Tg) and / or the melt viscosity of the cellulose ester. Plasticizers for cellulose esters can include triacetin (triacetin), diacetin (sugar glycerin), dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, poly(ethylene glycol) MW 200-600, dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl phthalyl ethyl glycolate, triethylene glycol dipropionate, 1,2- epoxypropyl phenyl glycol, 1,2-epoxypropyl(m-methylphenyl)glycol, 1,2- epoxypropyl(o-methylphenyl)glycol, beta-oxyethyl cyclohexene carboxylate, bis(cyclohexanoate) diethylene glycol, triethyl citrate, polyethylene glycol, propylene glycol, polysorbate esters, sucrose octaacetate, acetylated triethyl citrate, acetyltributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and ethylene glycol trimesate, plasticizers containing benzoate esters such as Benzoflex TM Plasticizer series, poly(alkyl succinate)s such as poly(butyl succinate), polyether sulfone, o-tolyl p-toluenesulfonate, N-ethyl toluene sulfonamide, adipate-based plasticizers, soybean oil epoxide such as ParaplexTM Plasthall® series plasticizers, sucrose-based plasticizers, dibutyl sebacate, glyceryl tributyrate, sucrose acetate isobutyrate, Resolflex TM Plasthall® series plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (e.g., ethyl phthalyl ethyl glycolate “EPEG” and methyl phthalyl ethyl glycolate “MPEG”), methoxy polyethylene glycol, 2,2,4-trimethylpentane-1,3-diyl bis(2-methylpropanoate), and polycaprolactone. In some embodiments, the plasticizer used herein can comprise a combination or mixture of two or more different types of plasticizers.

[0067] In one embodiment, or in combination with any other embodiment, the plasticizer has a boiling point of at least 100°C, or at least 200°C, and / or no more than 400°C, or no more than 300°C.

[0068] In one embodiment, or in combination with any other embodiment, the plasticizer is a food compliant plasticizer. Food compliance means compliance with applicable food additive and / or food contact regulations, where the plasticizer is approved for use or deemed safe by at least one (national or regional) food safety regulatory agency (or organization), such as being listed in 21 CFR Food Additive Regulations or otherwise being listed as Generally Recognized as Safe (GRAS) by the U.S. FDA. In one embodiment, or in combination with any other embodiment, the food compliant plasticizer is triacetin or polyethylene glycol (PEG) having a molecular weight of about 200 to about 600. In one embodiment, or in combination with any other embodiment, examples of food compliant plasticizers that can be considered can include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate esters, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, glyceryl tripropionate, Scandiflex, poloxamer copolymer, polyethylene succinate, diisobutyl adipate, polyvinyl pyrrolidone, and tribenzic acid glycol ester.

[0069] In an embodiment, or in combination with any other embodiment, the plasticizer can be 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 an embodiment, or in combination with any other embodiment, the plasticizer is present in an amount of 1 to 40 weight percent, based on the weight of the cellulose ester composition; or 5 to 25 weight percent, or 10 to 25 weight percent, or 12 to 20 weight percent, for most thermoplastic processing. In an embodiment, or in combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be accomplished with plasticizer levels in the range of 10 to 30 weight percent, or 12 to 25 weight percent, or 15 to 20 weight percent, or 10 to 25 weight percent, based on the weight of the cellulose ester composition.

[0070] In an 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, plasticizers containing benzoate esters such as Benzoflex 9-H TM plasticizer series, poly(succinates) such as poly(butylene succinate), polyether sulfone, adipate-based plasticizers, soybean oil epoxide such as Paraplex G-25 TM plasticizer series, sucrose-based plasticizers, dibutyl sebacate, glycerol tributyrate, Resoflex 101 TM plasticizer series, triphenyl phosphate, glycolate esters, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diyl bis(2-methylpropanoate), and polycaprolactone.

[0071] In an embodiment, or in combination with any other embodiment, the cellulose ester composition can contain a plasticizer selected from 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 disintegrable.

[0072] In an 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.

[0073] In an embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol having an average molecular weight of 300 to 500 daltons.

[0074] In an embodiment or in combination with any other embodiment, the cellulose ester composition includes at least one plasticizer (as described herein) in an amount of 1 wt% to 40 wt%, or 5 wt% to 40 wt%, or 10 wt% to 40 wt%, or 12 wt% to 40 wt%, 13 wt% to 40 wt%, or 15 wt% to 40 wt%, or greater than 15 wt% to 40 wt%, or 17 wt% to 40 wt%, or 20 wt% to 40 wt%, or 25 wt% to 40 wt%, or 5 wt% to 35 wt%, or 10 wt% to 35 wt%, or 13 wt% to 35 wt%, or 15 wt% to 35 wt%, or greater than 15 wt% to 35 wt%, or 17 wt% to 35 wt%, or 20 wt% to 35 wt%, or 5 wt% to 30 wt%, or 10 wt% to 30 wt%, or 13 wt% to 30 wt%, or 15 wt% to 30 wt%, or greater than 15 wt% to 30 wt%, or 17 wt% to 30 wt%, or 5 wt% to 25 wt%, or 10 wt% to 25 wt%, or 13 wt% to 25 wt%, or 15 wt% to 25 wt%, or greater than 15 wt% to 25 wt%, or 17 wt% to 25 wt%, or 5 wt% to 20 wt%, or 10 wt% to 20 wt%, or 13 wt% to 20 wt%, or 15 wt% to 20 wt%, or greater than 15 wt% to 20 wt%, or 17 wt% to 20 wt%, or 5 wt% to 17 wt%, or 10 wt% to 17 wt%, or 13 wt% to 17 wt%, or 15 wt% to 17 wt%, or greater than 15 wt% to 17 wt%, or 5 wt% to less than 17 wt%, or 10 wt% to less than 17 wt%, or 13 wt% to less than 17 wt%, or 15 wt% to less than 17 wt%, all based on the total weight of the cellulose ester composition.

[0075] In an embodiment or in combination with any other embodiment, the at least one plasticizer includes or is a food-compliant or FDA-approved plasticizer. In an embodiment or in combination with any other embodiment, the food-compliant or FDA-approved plasticizer includes or is triacetin or PEG MW 300 to 500.

[0076] Biodegradable polymer

[0077] 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 can include one or more of the cellulose esters described herein; and a biodegradable polymer component comprising at least one other biodegradable polymer (not a BCE). In one embodiment or in combination with any other embodiment, the other biodegradable polymer can be selected from the group consisting of polyhydroxyalkanoates (PHAs 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, starches, 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 the biodegradable polymer (not a 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, the cellulose ester composition contains the biodegradable polymer (not a BCE) in an amount of 0.1 wt.% to less than 50 wt.%, or 1 wt.% to 40 wt.%, or 1 wt.% to 30 wt.%, or 1 wt.% to 25 wt.%, or 1 wt.% to 20 wt.%, based on the total amount of BCE and biodegradable polymer. In one embodiment or in combination with any other embodiment, the at least one biodegradable polymer comprises a PHA having a weight average molecular weight (Mw) in the range 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 900,000, or 700,000 to 800,000, or 10,000 to 500,000, or 10,000 to 250,000, or 10,000 to 100,000, or 10,000 to 50,000, measured using gel permeation chromatography (GPC) with a refractive index detector and polystyrene standards using methylene chloride solvent. In one embodiment or in combination with any other embodiment, the PHA can include polyhydroxybutyrate-co-hydroxyhexanoate.

[0078] Nucleating agent

[0079] Nucleating agent means a chemical or physical material that provides sites for the formation of cells in a molten formulation mixture, such as within a CE molten composition. As will be described in greater detail below, the nucleating agent can be added to the compounded CE material during the compounding process. Alternatively or additionally, the nucleating agent can be added during the production of the foamed sheet material. For example, the nucleating agent can be blended with the formulation introduced into the hopper of the extruder of the extrusion section. Alternatively, the nucleating agent can be added to the CE molten composition within the extruder itself. The nucleating agent can include physical nucleating agents and chemical nucleating agents. Physical nucleating agents are materials that are immiscible with the polymer matrix of the CE molten composition at the extrusion temperature of the extrusion section. Chemical nucleating agents are materials that react (e.g., decompose) to form a physical nucleating agent during extrusion (e.g., at the extrusion temperature within the extruder). Thus, the chemical nucleating agent can be considered (and referred to herein as) a precursor to the physical nucleating agent formed in situ.

[0080] A suitable physical nucleating agent will include fine particles having a desired particle size and / or shape to create cell nucleation sites within the CE molten composition. For example, in some embodiments, the average particle size of the physical nucleating agent will be 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, particles having nanoscale dimensions can be preferred. Further, 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. Further, as noted above, the physical nucleating agent should be immiscible with the polymer matrix of the CE molten composition at the extrusion temperature of the extrusion section. Thus, in some embodiments, the melting temperature of the physical nucleating agent should be 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 to have the ability to recrystallize upon cooling after melting.

[0081] Examples of suitable inorganic physical nucleating agents include, but are not limited to, minerals such as talc, CaC03, 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 (AI(OH)3), MDH (Mg(OH)2), diatomite, 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 a mixed metal oxide, such as an oxide selected from one or more of: 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: magnesium silicate and calcium silicate.

[0082] It has been discovered that biodegradable natural particulate materials derived from renewable organic sources (e.g., organic nucleating agents) also function as effective physical nucleating agents. Natural materials that can function as physical nucleating agents include materials composed of cellulose fibers and / or cellulose starch. Examples include, but are not limited to, almond shell flour, animal fibers, apricot kernel shell flour, bamboo flour, bark flour, clam shell flour, coconut shell flour, coconut coir, cork flour, corn cob flour, corn cob grits, cotton seed hulls, cotton linters and fibers, hazelnut shell flour, kenaf flour, natural fibers, nut shells and flour, oat fiber flour, olive pit flour, peanut shell flour, pecan shell flour, pine nut shell flour, pistachio shell flour, plant fibers, rice hull flour, rice hulls, rice hulls, soy flour, starch flour (hydrophobic), walnut shell flour, wheat bran, wheat hulls, and wood flour. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, metal stearate salts, carbon black, and dolomite.

[0083] As noted above, suitable chemical nucleating agents (or precursors to physical nucleating agents formed in situ) are configured to decompose when a threshold chemical reaction temperature is reached to create cell nucleation sites in the CE melt composition. These small cells act as nucleation sites for larger cell growth from the physical blowing agent or other types of blowing agents. In some embodiments, the precursors are configured to form a gas such as CO2or N2during the extrusion of the particulate material.

[0084] Examples of chemical nucleating agents include, but are not limited to, acids such as citric acid or citric acid-based materials. Other acids can include lauric acid, stearic acid, tartaric acid, ascorbic acid, propionic acid, and caproic acid. One representative example is HYDROCEROL TMCF-40E (commercially available from Clariant Corporation) which contains citric acid and a crystal nucleating agent. In some embodiments, the chemical nucleating agent will include a combination of an acid and a base, such as a carbonate salt, which can include sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, and the like. 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 components of the nucleating agent are dispersed. For example, yet 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 comprise other compositions, such as various biopolymers (e.g., polybutylene succinate, Capa polyester, and the like), polyolefins, acrylic copolymers (e.g., ethylene methyl acrylate), and the like. In some such embodiments, the citric acid and sodium bicarbonate can constitute about half (wt.%) of the chemical nucleating agent, with the carrier constituting the other half (wt.%). Further, in some such embodiments, the sodium bicarbonate can be more than the citric acid in the chemical nucleating agent. For example, the sodium bicarbonate can be about three times as much (wt.%) as the citric acid in the chemical nucleating agent. It will also be appreciated that, in some embodiments, a carrier can not be needed or used, such as where the nucleating agent is Hecofoam or Hydrocerol.

[0085] In one embodiment or in combination with any of the embodiments mentioned herein, the nucleating agent is present in an amount of 0.1 wt.% to 10 wt.%, 0.1 wt.% 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.

[0086] Notably, whether in the form of a compounded CE material or a CE melt composition, the cellulose ester material is generally able to accept a maximum amount of nucleating agent that can function to form nucleation sites. Any remaining nucleating agent added to the cellulose ester material will remain as a filler. Based on the type of filler used, the filler can provide various properties to the resulting cellulose ester foam and / or article. For example, some fillers can provide increased / decreased density, ductility, Young's modulus, yield strength, heat deflection temperature, permeability, impact resistance, elongation at break, adhesion properties, biodegradability, etc. of the cellulose ester material. Fillers can also be used to alter the visual properties (e.g., color, opacity, etc.) and tactile properties (e.g., material continuity, surface roughness, etc.) of the cellulose ester material.

[0087] Blowing agent

[0088] Blowing agent refers to a physical or chemical material (or combination of materials) used to expand nucleation sites. The blowing agent can include a chemical blowing agent, a physical blowing agent, a combination thereof, or several types of chemical and physical blowing agents. The role of the blowing agent is to reduce the density of the material by expanding the cells formed in the melt formulation at the nucleation sites. The blowing agent can be added to the CE melt composition in the extruder. Surprisingly, it has been found that the hygroscopic properties of biodegradable natural particulate fillers allow them to absorb moisture and carry the absorbed water into the molten resin mixture, where the water can act as a physical blowing agent.

[0089] Examples of physical blowing agents include H2O, N2, CO2, alkanes, alkenes, ethers, ketones, argon, helium, air, or mixtures. Additionally, it has been surprisingly found that the hygroscopic properties of biodegradable particulate natural fillers allow them to absorb moisture and carry the absorbed water into the molten resin mixture, where the water can act as a physical blowing agent. The hygroscopic biodegradable natural fillers can be formulated into a composition and allowed to absorb moisture prior to the foaming process, where the water is then released to act as a physical blowing agent. Advantageously, water can also act as a plasticizer for the cellulose ester resin. Furthermore, in some embodiments, the physical blowing agent can include a hydrocarbon, such as pentane / isopentane or butane / isobutane. Other hydrocarbons can include propane, ethane, methane, hexane, cyclohexane, cyclopentane, cyclobutene, etc.

[0090] Chemical blowing agents are materials that degrade or react to produce a gas (e.g., CO2or 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 blowing agents can be endothermic or exothermic. Chemical blowing agents typically degrade at a particular temperature to decompose and release a gas. Examples of chemical blowing agents include azodicarbonamide, acids (e.g., citric acid), and carbonates such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, and the like, and combinations thereof.

[0091] In one embodiment or in combination with any of the embodiments mentioned herein, the foaming agent is present in an amount of 0.3 wt% to 1.5 wt%, or 0.3 wt% to 2.0 wt%, or 0.3 wt% to 2.5 wt%, or 0.3 wt% to 3.0 wt%, or 0.3 wt% to 3.5 wt%, or 0.3 wt% to 4.0 wt%, or 0.3 wt% to 8%, or 1.3 wt% to 1.5 wt%, or 1.3 wt% to 2.0 wt%, or 1.3 wt% to 2.5 wt%, or 1.3 wt% to 3.0 wt%, or 1.3 wt% to 3.5 wt%, or 1.3 wt% to 4.0 wt%, or 1.3 wt% to 4.5 wt%, or 1.3 wt% to 5.0 wt%, or 1.3 wt% to 5.5 wt%, or 1.5 wt% to 3.0 wt%, or 1.5 wt% to 4.0 wt%, or 1.5 wt% to 5.0 wt%, or 1.5 wt% to 6.0 wt%, or 2.0 wt% to 3.0 wt%, or 2.0 wt% to 4.0 wt%, or 2.0 wt% to 5.0 wt%, or 2.0 wt% to 6.0 wt%, or 2.5 wt% to 3.0 wt%, or 2.5 wt% to 4.0 wt%, or 2.5 wt% to 5.0 wt%, or 2.5 wt% to 6.0 wt%, or 3.0 wt% to 4.0 wt%, or 3.0 wt% to 5.0 wt%, or 3.0 wt% to 6.0 wt%, or 0.0 wt% to 9.0 wt%, or 0.5 wt% to 9.0 wt%, or 1.0 wt% to 9.0 wt%, or 1.5 wt% to 9.0 wt%, or 2.0 wt% to 9.0 wt%, or 2.5 wt% to 9.0 wt%, or 3.0 wt% to 9.0 wt%, or 3.5 wt% to 9.0 wt%, or 4.0 wt% to 9.0 wt%, or 4.5 wt% to 9.0 wt%, or 5.0 wt% to 9.0 wt%, or 5.5 wt% to 9.0 wt%, or 6.0 wt% to 9.0 wt%, or 6.5 wt% to 9.0 wt%, or 7.0 wt% to 9.0 wt%, or 7.5 wt% to 9.0 wt%, or 8.0 wt% to 9.0 wt%, or 8.5 wt% to 9.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the foaming agent used herein can comprise a combination or mixture of two or more different types of foaming agents.

[0092] Surface modifying additive

[0093] Surface modification additives are materials that can be added to the cellulose ester composition to alter the structure of the composition (or the resulting foam article) to improve processing of the cellulose ester composition. For example, the inventors of the present application have discovered that adding a surface modification additive to the compounded CE material (e.g., to the pellets during the compounding process) or to the CE melt composition (e.g., during the extrusion process) can improve processing by reducing the unnecessary sticking of the CE melt composition to the die or mandrel (or other components of the foam sheet production process). This sticking reduction can be achieved by the surface modification additive inhibiting the melting of the cellulose ester caused by the plasticizer. Adding a surface modification additive can also reduce the blocking 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 it to be performed at lower temperatures.

[0094] Furthermore, in some embodiments, the surface modification additive can act as an anti-static additive that inhibits electrical sparks or arcs in the CE melt composition. Inhibiting electrical sparks or arcs can be particularly important when using a hydrocarbon as the blowing agent to reduce the chance of igniting the hydrocarbon and causing a fire. Advantageously, the surface modification additive can also reduce the outward diffusion of the blowing agent, such as a hydrocarbon, from the foam sheet or resulting article. In some embodiments, the hydrocarbon itself can act as a surface modification additive.

[0095] However, more general examples of surface modification additives that can be used with the compounded CE material (e.g., during the compounding process) or with the CE melt composition (e.g., during the foam sheet production process) in accordance with embodiments of the present application include fatty acids such as palmitic acid, tallow acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, arachidic acid, behenic acid, and erucic acid. The surface modification additives can also include fatty acid amides such as erucamide, oleamide, stearamide, benzamide, secondary amides, and bisamides.

[0096] Further examples of surface modifying additives can include glycerol esters and / or stearates, such as monoglycerides, diglycerides, and triglycerides. The monoglycerides can include glycerol monostearate or glycerol monostearate derivatives, such as diacetyl tartaric acid esters of monoglycerides and diglycerides (DATEM), ethoxylated monoglycerides, succinylated monoglycerides, and propylene glycol monoesters (PGME). Examples of surface modifying additives can also include metal stearates, such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate, and / or combinations thereof (e.g., calcium stearate / zinc stearate). Examples of surface modifying additives can also include waxes, such as polyolefin waxes (polypropylene waxes and polyethylene waxes), oxidized olefin waxes, ethylene acrylic acid (EAA) copolymer waxes, ethylene methyl acrylate (EMA) copolymer waxes, EAA ionomer waxes, acrylic waxes, and / or natural waxes, such as rice bran wax, sunflower wax, sugar cane wax, candelilla wax, soy wax, beeswax, camauba wax, and carnauba wax.

[0097] Other non-exclusive examples of surface modifying additives include aliphatic diesters (e.g., dioctyl adipate), polyglycol diesters, alkyl alkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters, and alkyl monoesters. Additionally, various oils can be used as surface modifying additives, such as aromatic oils, naphthenic oils, glycerol ester oils, silicone oils, and epoxidized oils (e.g., soybean oil and linseed oil). Thus, in some embodiments, the surface modifying additive comprises a plasticizer, such as an aliphatic diester plasticizer, a polyester plasticizer, and the like. Furthermore, in some embodiments, the surface modifying additive can comprise a polyhedral oligomeric silsesquioxane (POSS).

[0098] More generally, the surface modifying additives used in embodiments of the present application can have a lower polarity than the cellulose ester in the compounded CE material (e.g., during the compounding process) or the CE melt composition (e.g., during the production of the foam sheet). For example, the surface modifying additive can have (based on Hansen solubility parameters): a total solubility parameter δ 1 / 2 of less than 25 MPa 1 / 2 or less than 19.5 MPa 1 / 2 ; a dispersion force solubility parameter δ d of less than 18 MPa 1 / 2 , less than 16 MPa 1 / 2 , or less than 14 MPa 1 / 2 ; a dipole-dipole intermolecular force solubility parameter δ d of less than 12 MPa 1 / 2 , less than 8 MPa 1 / 2 , or less than 4 MPa 1 / 2 ; and / or a hydrogen bonding solubility parameter δ h of less than 11 MPa 1 / 2less than 10 MPa 1 / 2 or less than 9 MPa 1 / 2 However, in some other embodiments, the surface modifying additive used in embodiments of the present application can have a polarity higher than the cellulose ester in the compounded CE material (e.g., during the compounding process) or the CE melt composition (e.g., during the foam sheet production process). For example, the surface modifying additive can have (based on Hansen solubility parameters): a total solubility parameter delta (delta) greater than 21.5 MPa 1 / 2 greater than 23 MPa 1 / 2 or greater than 25 MPa 1 / 2 Additionally, in some embodiments, the surface modifying additive can have a boiling point higher than 200 °C, higher than 220 °C, higher than 240 °C, higher than 260 °C, higher than 280 °C, or higher than 300 °C. Furthermore, the surface modifying additive can 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 not more than 1000 g / mol, not more than 2500 g / mol, or not more than 5000 g / mol. Still further, it can be preferred that the surface modifying additive is not soluble in the plasticizer(s) used in the cellulose ester composition. For example, it can be preferred that the surface modifying additive is not soluble in triacetin. Finally, in some embodiments, the surface modifying additive can be biodegradable and / or food compliant or FDA approved.

[0099] In one embodiment or in combination with any of the embodiments mentioned herein, the surface modifying additive is present in an amount of 0.05 wt% to 0.75 wt%, or 0.05 wt% to 1.0 wt%, or 0.05 wt% to 2.5 wt%, or 0.05 wt% to 5.0 wt%, or 0.75 wt% to 1.0 wt%, or 0.75 wt% to 2.5 wt%, or 0.75 wt% to 5.0 wt%, or 0.1 wt% to 1.0 wt%, or 0.1 wt% to 2.5 wt%, 0.1 wt% to 5.0 wt%, or 1.0 wt% to 2.5 wt%, or 1.0 wt% to 5.0 wt%, or 2.5 wt% to 5.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the surface modifying additive used herein can comprise a combination or mixture of two or more different types of surface modifying additives.

[0100] Article

[0101] Extruded sheets of cellulose ester foam can be formed using the extrusion section and / or sheet forming section described above. Such extruded sheets comprise a structural material interspersed with a plurality of gaseous voids thereon. Such gaseous voids are formed by expansion of a blowing agent in gaseous form within a cellulose polymer melt. The structural material is cellulose ester-based, having a particular amount of the 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 the extruded sheets of foam according to embodiments, and can be particularly useful in the food service industry. Exemplary articles include meat trays. The articles can have one or more particularly advantageous properties. For example, the articles can be biodegradable and / or compostable, and / or the articles can have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0102] In one embodiment or in combination with any of the embodiments mentioned herein, the density of the foam is less than 0.20 g / cm3 3 , less than 0.18 g / cm3 3 , less than 0.15 g / cm3 3 , less than 0.12 g / cm3 3 , less than 0.10 g / cm3 3 , less than 0.08 g / cm3 3 , less than 0.06 g / cm3 3 , or less than 0.04 g / cm3 3 , or from 0.04 g / cm3 3 to 0.8 g / cm3 3 , from 0.04 g / cm3 3 to 0.6 g / cm3 3 , from 0.04 g / cm3 3 to 0.5 g / cm3 3 , from 0.04 g / cm3 3 to 0.4 g / cm3 3 , from 0.04 g / cm3 3 to 0.3 g / cm3 3 , from 0.04 g / cm3 3 to 0.2 g / cm3 3 , from 0.04 g / cm3 3 to 0.15 g / cm3 3 , from 0.04 g / cm3 3 to 0.12 g / cm3 3 , from 0.04 g / cm3 3 to 0.10 g / cm3 3 , from 0.04 g / cm3 3 to 0.08 g / cm3 3 , from 0.04 g / cm3 3to 0.06 g / cm 3 , 0.06 g / cm 3 to 0.8 g / cm 3 , 0.06 g / cm 3 to 0.6 g / cm 3 , 0.06 g / cm 3 to 0.5 g / cm 3 , 0.06 g / cm 3 to 0.4 g / cm 3 , 0.06 g / cm 3 to 0.3 g / cm 3 , 0.06 g / cm 3 to 0.2 g / cm 3 , 0.06 g / cm 3 to 0.15 g / cm 3 , 0.06 g / cm 3 to 0.12 g / cm 3 , 0.06 g / cm 3 to 0.10 g / cm 3 , 0.06 g / cm 3 to 0.08 g / cm 3 , 0.08 g / cm 3 to 0.8 g / cm 3 , 0.08 g / cm 3 to 0.6 g / cm 3 , 0.08 g / cm 3 to 0.5 g / cm 3 , 0.08 g / cm 3 to 0.4 g / cm 3 , 0.08 g / cm 3 to 0.3 g / cm 3 , 0.08 g / cm 3 to 0.2 g / cm 3 , 0.08 g / cm 3 to 0.15 g / cm 3 , 0.08 g / cm 3 to 0.12 g / cm 3 , 0.08 g / cm 3 to 0.10 g / cm 3 , 0.1 g / cm 3 to 0.8 g / cm 3 , 0.1 g / cm 3 to 0.6 g / cm 3 , 0.1 g / cm 3 to 0.5 g / cm 3 , 0.1 g / cm 3 to 0.4 g / cm3 0.1 g / cm 3 to 0.3 g / cm 3 0.1 g / cm 3 to 0.2 g / cm 3 0.1 g / cm 3 to 0.15 g / cm 3 0.1 g / cm 3 to 0.12 g / cm 3 0.2 g / cm 3 to 0.8 g / cm 3 0.2 g / cm 3 to 0.6 g / cm 3 0.2 g / cm 3 to 0.5 g / cm 3 0.2 g / cm 3 to 0.4 g / cm 3 0.2 g / cm 3 to 0.3 g / cm 3 0.3 g / cm 3 to 0.6 g / cm 3 0.3 g / cm 3 to 0.5 g / cm 3 0.3 g / cm 3 to 0.4 g / cm 3 0.4 g / cm 3 to 0.6 g / cm 3 0.4 g / cm 3 to 0.5 g / cm 3 or 0.5 g / cm 3 to 0.6 g / cm 3 .

[0103] In one embodiment or in combination with any of the embodiments mentioned herein, the average foam cell size is 40 pm to 600 pm, or 50 pm to 600 pm, or 60 pm to 600 pm, or 70 pm to 600 pm, or 80 pm to 600 pm, or 90 pm to 600 pm, or 100 pm to 600 pm, or 150 pm to 600 pm, or 200 pm to 600 pm, or 250 pm to 600 pm, or 300 pm to 600 pm, or 400 pm to 600 pm, or 500 pm to 600 pm, or 40 pm to 550 pm, or 40 pm to 500 pm, or 40 pm to 450 pm, or 40 pm to 400 pm, or 40 pm to 350 pm, or 40 pm to 300 pm, or 40 pm to 250 pm, or 40 pm to 200 pm, or 40 pm to 150 pm, or 40 pm to 100 pm.

[0104] Further inventive concepts related to processes and systems for producing pellets, foamed sheet, and / or articles.

[0105] As described above, embodiments of the present application include a forming mandrel design and processes and systems for recycling liquids produced during the production of biodegradable compositions, sheets, and articles. These liquids can contain valuable plasticizers or other components that would otherwise be lost or disposed of in conventional processes and systems. For example, under standard operations, the processes and methods described herein are capable of recycling and optionally reusing at least 0.1 gallons, at least 0.5 gallons, or at least 1 gallon (about 1,000 pounds / hour) of plasticizer per hour that would otherwise be lost or disposed of in conventional processes and systems.

[0106] Embodiments described herein are particularly useful in the production of cellulose ester foamed sheet and articles, but the embodiments can also be used in other sheet and article production applications.

[0107] In one embodiment or in combination with any of the embodiments mentioned herein, a biodegradable cellulose acetate foam or article can be produced that is industrially compostable or home compostable. In one subclass of this category, the foam or article is industrially compostable. In one subsubclass of this subclass, the foam or article has a thickness of less than 6 mm. In one subsubclass of this subclass, the foam or article has a thickness of less than 3 mm. In one subsubclass of this subclass, the article has a thickness of less than 1.1 mm. In one subclass of this category, the foam or article is home compostable. In one subsubclass of this subclass, the foam or article has a thickness of less than 6 mm. In one subsubclass of this subclass, the foam or article has a thickness of less than 3 mm. In one subsubclass of this subclass, the foam or article has a thickness of less than 1.1 mm. In one subsubclass of this subclass, the foam or article has a thickness of less than 0.8 mm. In one subsubclass of this subclass, the foam or article has a thickness of less than 0.6 mm. In one subsubclass of this subclass, the foam or article has a thickness of less than 0.4 mm.

[0108] In an embodiment or in combination with any of the embodiments mentioned herein, the thickness of the foam or article is 1 mm to 10 mm, 1 mm to 8 mm, 2 mm to 8 mm, 3 mm to 7 mm, 4 mm to 6 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, or about 8 mm. However, it should be noted that the foam or article can have other larger dimensions. For example, in some embodiments, the foam or article can have a thickness of 0.5 inches to 24 inches, 1 inch to 15 inches, or 3 inches to 12 inches. In some embodiments, the foam or article can have a thickness of 100 mils to 400 mils, 120 mils to 300 mils, or 150 mils to 250 mils.

[0109] In an embodiment or in combination with any of the embodiments mentioned herein, the foam or article exhibits greater than 90% disintegration after 12 weeks according to the disintegration test protocol for films as described in the specification.

[0110] The composition for making the biodegradable cellulose acetate foam can include other additives such as fillers, stabilizers, odor modifiers, waxes, compatibilizers, biodegradation promoters, dyes, pigments, colorants, lubricants, antioxidants, viscosity regulators, antifungal agents, heat stabilizers, antibacterial agents, softening agents, mold release agents, UV absorbers, and combinations thereof. Each additional additive can be present in the cellulose ester-based material in an amount less than 10 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1.0 wt%. It should be noted that the same type of compound or material can be identified as or included in multiple categories of components in the cellulose acetate composition. For example, polyethylene glycol (PEG) can function as a plasticizer or as an additive that does not function as a plasticizer, such as a hydrophilic polymer or a biodegradation promoter, for example, where the lower molecular weight PEG has a plasticizing effect, while the higher molecular weight PEG functions as a hydrophilic polymer but not as a plasticizer.

[0111] In an embodiment or in combination with any other embodiment mentioned herein, the foam, composition, or foamable composition further comprises a photodegradation catalyst. In one class of this embodiment, the photodegradation catalyst is titanium dioxide or iron oxide. In one subclass of this class, the photodegradation catalyst is titanium dioxide. In one subclass of this class, the photodegradation catalyst is iron oxide.

[0112] In one embodiment, or in combination with any other embodiment mentioned herein, the foam, composition, or foamable composition further comprises a pigment. In one class of this embodiment, the pigment is titanium dioxide, carbon black, or iron oxide. In one subclass of this class, the pigment is titanium dioxide. In one subclass of this class, the pigment is carbon black. In one subclass of this class, the pigment is iron oxide. In one subclass of this class, the pigment is a biodegradable natural particulate filler.

[0113] Definitions

[0114] It should be understood that the following description is not intended to be an exhaustive list of the defined terms. Other definitions can be provided in the foregoing description, such as, for example, as the use of the defined terms is accompanied in context.

[0115] As used herein, the terms "a," "an," and "the" mean one or more.

[0116] As used herein, the terms "comprising," "comprises" and "comprise" are open-ended transitional phrases used to transition from the subject matter recited in the clause in which the transitional phrase is used to one or more elements recited after the transitional phrase, wherein the one or more elements recited after the transitional phrase are not necessarily the only elements that make up the subject matter.

[0117] To be considered "compostable," a material must meet the following four criteria: (1) the material should pass the biodegradation requirement in the test at elevated temperature (58°C) under controlled composting conditions according to ISO 14855-1 (2012), which corresponds to an absolute 90% biodegradation or a relative 90% biodegradation relative to the control polymer; (2) the material tested under aerobic composting conditions according to ISO 16929 (2013) must achieve a 90% degree of disintegration; (3) the test material must meet all requirements regarding volatile solids, heavy metals, and fluorine as specified by ASTM D6400 (2012), EN 13432 (2000), and ISO 17088 (2012); and (4) the material should not have a negative impact on plant growth.

[0118] As used herein, the term "biodegradable" generally refers to the biological transformation and consumption of an organic molecule. Biodegradability is an inherent property of the material itself and materials can exhibit different 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 into smaller pieces when exposed to specific conditions. The degree of disintegration depends on the material itself as well as 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.

[0119] According to French Norm NF T 51-800 and Australian Standard AS 5810, a material must exhibit a total biodegradation of at least 90% (e.g., compared to the initial sample), or a biodegradation of at least 90% of the maximum degradation of the appropriate reference material after the reference and test items have both reached the stationary phase, to be considered "biodegradable" under home composting conditions. The maximum test duration for biodegradation under home composting conditions is 1 year.

[0120] According to ASTM D6400 and ISO 17088, at least 90% of the organic carbon in the entire item (or for each component present in an amount exceeding 1% by dry mass) must be converted to carbon dioxide at the end of the test period when compared to a control or absolute value, for a material to be considered "biodegradable" under industrial composting conditions. According to European Standard ED 13432 (2000), a material must exhibit a total biodegradation of at least 90%, or a biodegradation of at least 90% of the maximum degradation of the appropriate reference material after the reference and test items have both reached the stationary phase. The maximum test duration for biodegradability under industrial composting conditions is 180 days.

[0121] According to OK Biodegradable Soil compliant mark of the OK Compost Consortium and the DIN Geprüft Soil Biodegradable Certification scheme of DIN CERTCO, a material must exhibit a total biodegradation of at least 90% (e.g., compared to the initial sample), or a biodegradation of at least 90% of the maximum degradation of the appropriate reference material after the reference and test items have both reached the stationary phase, to be considered "biodegradable" under soil composting conditions. The maximum test duration for biodegradability under soil composting conditions is 2 years.

[0122] The claims are not limited to the disclosed embodiments

[0123] The above-described preferred forms of the present application are to be used as illustrations only and should not be utilized in a limiting sense to interpret the scope of the present application. Modifications to the exemplary embodiments set forth above can be readily made by those skilled in the art and the examples set forth herein should be interpreted as illustrative and not in a limiting sense.

[0124] The inventors hereby declare that they intend to determine and evaluate the reasonable and equivalent field of the present invention according to the doctrine of equivalents, to the same extent as under 35 U.S.C. § 112, 6th paragraph, as interpreted pursuant to 35 U.S.C. § 103, because it involves devices not materially departing from the scope of the present invention as set forth in the following claims.

Claims

1. A method for forming a foam sheet, the method comprising: (a) extruding the composition through an annular die to form a tubular extrudate; as well as (b) pulling the tubular extrudate over the surface of a forming mandrel, the surface of the forming mandrel being maintained at a temperature above 30°C.

2. The method according to claim 1, further comprising: The temperature of the surface of the forming mandrel is controlled using indirect heat exchange with a heat transfer medium.

3. The method of claim 2, wherein the controlling comprises flowing the heat transfer medium through a conduit at least partially positioned adjacent the surface of the forming mandrel to provide indirect heat transfer between the heat transfer medium and the surface of the forming mandrel.

4. The method according to claim 2 or 3, wherein the heat transfer medium is selected from one or more of the following: air, water, oil, glycol and mixtures thereof.

5. The method according to claim 3 or 4, wherein the heat transfer medium is introduced into the conduit at a temperature above 30°C.

6. The method according to claim 1, further comprising: The temperature of the surface of the forming mandrel is controlled by providing heat from one or more electrical heating elements positioned at least partially adjacent to the surface.

7. The method according to any one of claims 1 to 6, further comprising: The tubular extrudate is slit and film sheets are formed therefrom.

8. The method of any one of claims 1 to 7, wherein the composition comprises a cellulose ester and a plasticizer.

9. The method of claim 8, wherein the cellulose ester comprises cellulose diacetate.

10. The method of claim 8 or 9, wherein the plasticizer comprises triacetin.

11. A method for recovering liquid formed during a foam sheet forming process, the method comprising: (a) extruding the composition through an annular die to form a tubular extrudate; (b) drawing the tubular extrudate over a forming mandrel, the mandrel comprising an outer surface having one or more liquid collection features formed therein; (c) cooling the tubular extrudate to produce a foamed extrudate and a liquid condensate; as well as (d) directing at least a portion of the liquid condensate through the one or more liquid collection features to a liquid recovery system.

12. The method of claim 11, wherein the one or more liquid collection features include one or both of the following: (i) one or more channels formed in the outer surface, wherein the at least a portion of the liquid condensate collects in the one or more channels and flows through the one or more channels to the liquid recovery system; and (ii) one or more openings formed in the outer surface, wherein at least a portion of the liquid condensate passes through the one or more openings into the interior portion of the mandrel and flows through the interior portion to the liquid recovery system.

13. A method according to claim 11 or 12, wherein the liquid recovery system comprises a nozzle located downstream of the mandrel and operable to collect the liquid condensate.

14. The method of any one of claims 11 to 13, wherein the liquid recovery system comprises a conduit disposed at least partially within the mandrel and operable to collect the liquid condensate.

15. The method of any one of claims 11 to 14, wherein the liquid recovery system comprises a suction pump operable to remove the liquid condensate from the mandrel through the conduit.

16. The method of any one of claims 11 to 15, further comprising filtering the liquid condensate collected in the liquid recovery system to remove solids from the liquid condensate.

17. The method according to any one of claims 11 to 16, further comprising recycling at least a portion of the liquid condensate into the composition before or during the extrusion step (a).

18. The method of any one of claims 11 to 17, wherein the composition comprises a cellulose ester and a plasticizer.

19. The method of claim 18, wherein the cellulose ester comprises cellulose diacetate, wherein the liquid condensate comprises the plasticizer, and wherein the plasticizer comprises glycerol triacetate.

20. A method according to any one of claims 11 to 19, wherein the mandrel has an inclined axis of elongation.

21. A method for recovering liquid formed during a foam sheet forming process, the method comprising: (a) extruding the composition through an annular die to form a tubular extrudate; (b) drawing the tubular extrudate over a forming mandrel, the mandrel comprising an inclined elongated axis; (c) cooling the tubular extrudate to produce a foamed extrudate and a liquid condensate; and (d) directing at least a portion of the liquid condensate to a liquid recovery system.

22. The method of any one of claims 11 to 21, further comprising slitting the foamed extrudate and forming foam sheets therefrom.

23. The method of claim 21, wherein the mandrel further comprises one or more liquid collection features formed in an outer surface of the mandrel.

24. The method of claim 23, wherein the one or more liquid collection features include one or both of the following: (i) one or more channels formed in the outer surface, whereby the at least a portion of the condensate collects in the one or more channels and flows through the one or more channels to the liquid recovery system; and (ii) one or more openings formed in the outer surface, whereby said at least a portion of said condensate passes through said one or more openings into an interior portion of said mandrel and flows within said interior portion to said liquid recovery system.

25. The method of claim 24, wherein the liquid recovery system comprises a conduit disposed at least partially within the mandrel and operable to collect the liquid condensate.

26. The method of claim 25, wherein the liquid recovery system comprises a suction pump operable to remove the liquid condensate from the mandrel through the conduit.

27. A method according to any one of claims 21 or 23 to 26, wherein the liquid recovery system comprises a nozzle located downstream of the mandrel and operable to collect the liquid condensate.

28. The method of any one of claims 21 or 23 to 27, further comprising filtering the liquid condensate collected in the liquid recovery system to remove solids from the liquid condensate and recycling at least a portion of the liquid condensate into the composition before or during the extruding (a).

29. The method of any one of claims 21 or 23 to 28, wherein the composition comprises a cellulose ester and a plasticizer.

30. The method of claim 29, wherein the cellulose ester comprises cellulose diacetate, wherein the liquid condensate comprises the plasticizer, and wherein the plasticizer comprises glycerol triacetate.

Images