Cellulose ester microparticles with reduced moisture content for foam sheet production processes

Abstract

Cellulose ester pellets having reduced moisture content for use in the production of cellulose ester foam articles. The pellets can be dried after compounding such that it can be introduced into the extruder at a lower moisture content compared to conventional methods. The pellets may be packaged after compounding, and optionally dried to provide a granulated cellulose ester product having a low moisture content. High moisture content pellets may also be used to achieve desired foam article characteristics.

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 and viable compositions, methods, and systems for producing such articles.

[0002] Additionally, the moisture content of the pellets used to produce foamed products can typically result in foams having unacceptable cell size and quality. Thus, it is desirable to find alternative systems and methods that produce and utilize microparticles having a moisture content that can result in acceptable foamed products. SUMMARY

[0003] In one embodiment or in combination with any other embodiment mentioned herein, a foamable composition for a foamed sheet process is provided. The composition comprises dry cellulose ester microparticles having a moisture content of no more than 2000 ppm as determined by Karl Fischer titration and / or using a moisture measuring device.

[0004] In another embodiment or in combination with any other embodiment mentioned herein, a method of forming a dry microparticle material is provided. The method comprises: (a) providing a foamable microparticle composition comprising a cellulose ester and a plasticizer, the foamable microparticle composition having a moisture content; and (b) introducing the foamable microparticle composition into a drying system, thereby reducing the moisture content and forming a dry microparticle material.

[0005] In another embodiment or in combination with any other embodiment mentioned herein, a foamed sheet forming process is provided. The process comprises introducing a microparticle material comprising a cellulose ester and having a moisture content of 200 ppm to 5000 ppm into a foamed sheet extrusion process and producing a foamed sheet having one or more of: (i) an open cell content of less than 15%; (ii) an average cell size of less than 500 microns; (iii) a maximum cell size of less than 800 microns; (iv) a cell density of 100 to 3000 cells / cm 2 ; (v) a surface roughness R rms of less than 50 microns; and / or (vi) a cell span factor of no more than 1.25.

[0006] In another embodiment or in combination with any other embodiment mentioned herein, a method of forming a foamed sheet is provided. The method includes introducing a particulate material comprising a cellulose ester and having a moisture content of 5,000 ppm to 20,000 ppm into a foamed sheet extrusion process, and producing a foamed sheet having one or more of the following: (i) an open cell content of less than 10%; (ii) an average cell size of less than 500 microns; (iii) a maximum cell size of less than 800 microns; (iv) a cell density of less than 400 cells / cm 2 ; (v) a surface roughness R rms of at least 50 microns; and / or (vi) a cell span factor of greater than 0.75.

[0007] In another embodiment or in combination with any other embodiment mentioned herein, a method of forming a foamed sheet is provided. The method includes introducing a particulate material comprising a cellulose ester having a moisture content of greater than 10,000 ppm, 2-10 wt% of a (C 4-6 )alkane, less than 5 wt% talc, and 0.1 to 2 wt% of a chemical blowing agent into a foamed sheet extrusion process, and producing a foamed sheet having: (i) an open cell content of at least 15%; and (ii) a surface roughness R rms of less than 20 microns.

[0008] In another embodiment or in combination with any other embodiment mentioned herein, a method of packaging a particulate material is provided. The method includes: (a) providing a foamable particulate composition comprising a cellulose ester and a plasticizer and having a moisture content of no more than 3,000 ppm; and (b) introducing the particulate composition into a moisture resistant package, and sealing the composition therein. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a schematic illustration of a process for forming a biodegradable article according to an embodiment of the application;

[0010] Figure 2 is a schematic illustration of another process for forming a biodegradable article according to an embodiment of the application;

[0011] Figure 3 is a schematic illustration of an extrusion section that can be used in a process for forming an article according to an embodiment of the application; Figure 1 and / or Figure 2 ; is a schematic illustration of an extrusion section that can be used in a process for forming an article according to an embodiment of the application;

[0012] Figure 4 is a schematic illustration of an extrusion section that can be used in a process for forming an article according to an embodiment of the application; Figure 1 and Figure 2FIG. 2 is a schematic illustration of another extrusion section in an article forming process according to embodiments of the present application;

[0013] Figure 5 FIG. 3 is a schematic illustration of a sheet forming section in an article forming process according to embodiments of the present application. Figure 1 and / or Figure 2 FIG. 4 is a schematic illustration of a sheet forming section in an article forming process according to embodiments of the present application.

[0014] Figure 6 FIG. 5 is a schematic illustration of a volatile recovery system according to embodiments of the present application. DETAILED DESCRIPTION

[0015] Embodiments generally relate to methods, systems, and compositions for forming biodegradable particulate material (e.g., pellets), foamed sheet, and articles. Exemplary methods including the methods, systems, and compositions are depicted in FIG. 1 and described in greater detail below. Figures 1-5

[0016] Methods and Systems

[0017] As shown in FIGS. 1 and 2, raw materials can be introduced into a biodegradable polymer production process that produces a biodegradable polymer material. In one embodiment or in combination with any other embodiment mentioned herein, the biodegradable polymer material includes 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 dissolving grade pulp and / or paper grade pulp. The cellulose in the pulp can be esterified, for example, with acetate to form a biodegradable cellulose ester polymer, such as a cellulose acetate polymer. Figure 1 Figure 2 The biodegradable polymer material can then be introduced into a compounding process, where the biodegradable polymer material can be mixed with a plasticizer and, optionally, one or more other additives (e.g., stabilizers) and formed into a compounded material that includes a plasticized biodegradable polymer. Other additives can also be mixed with the polymer and plasticizer. For example, as shown in FIG. 3, the other materials (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. The 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 tumbler mixing.

[0018] The biodegradable polymer material can then be introduced into a compounding process, where the biodegradable polymer material can be mixed with a plasticizer and, optionally, one or more other additives (e.g., stabilizers) and formed into a compounded material that includes a plasticized biodegradable polymer. Other additives can also be mixed with the polymer and plasticizer. For example, as shown in FIG. 3, the other materials (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. The 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 tumbler mixing. Figure 2

[0019] ​​​The compounding process can include a pelletization process. The pelletization process can generally include mixing the biodegradable polymer material, plasticizer, and one or more other additives to form a mixed composition, and forming a particulate material from the composition. In particular, the pelletization process can include a granulation process, and the particulate material can include an amount of granules. 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 particulate material or granules. It will be appreciated that, as used herein, the phrase "pelletization" or "pelletization process" can be the same as or can at least include "granulation" or "granulation process." In some embodiments, the pelletization process can include granulation into a water bath, granulation on an air cooling belt, underwater pelletization, solvent compounding, etc.

[0020] 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 2-6 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 desirable size and shape, referred to as "granules" or "pellets." Although methods for forming granulated compounded materials are described herein, it will be appreciated that, in accordance with some embodiments, the compounded material fed to the foam sheet production method can be in any physical shape (e.g., granules, powder, pellets, 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 particulate material (e.g., granules, powder, pellets, fibers, etc.).

[0021] The particulate CE material produced during compounding can typically have a moisture content (i.e., water content) of about 3000 ppm to about 10,000 ppm, depending on the environmental and processing conditions. However, for some applications, such a high level of moisture content can produce unacceptably large cell sizes in the resulting foam, resulting in poor foam quality. Thus, in one embodiment or in combination with any other embodiment mentioned herein, at least a portion of the particulate CE material produced during compounding can be dried by introducing the material into a drying system to reduce the moisture content and thereby provide a dried particulate material.

[0022] In one embodiment or in combination with any other embodiment mentioned herein, the particulate CE material can be contacted with a forced vapor (e.g., air) stream through the drying system. For example, compressed dry air can be used at a temperature and humidity sufficient to draw water from the composition. The drying temperature (i.e., the temperature of the vapor stream) can be at least 60 °C below the Tg of the CE material. Thus, the forced vapor stream can have a temperature of 40 °C to 80 °C or 50 °C to 70 °C. In some embodiments, the forced vapor stream can be cooled and contacted with a desiccant material. Cooling the gaseous stream prior to contact with the desiccant material can advantageously condense certain volatiles (for collection and / or reuse) and can allow the desiccant to work more efficiently. Additionally or alternatively, other drying methods can also be used, which can include one or more heating steps, air drying, and / or cyclone drying processes.

[0023] In one embodiment or in combination with any other embodiment mentioned herein, the forced vapor stream used in the drying system can be processed to remove (and optionally collect) volatiles and / or particulate matter (e.g., dust, fines, etc.) entrained therein, which allows the processed vapor stream to be recycled for use in the drying system. Figure 6An exemplary system for processing a vapor stream is depicted. The vapor stream is passed through an inlet feed, where the vapor stream can optionally first be subjected to particulate filtration to remove dust and other fine particulate matter. The vapor stream at the inlet can have a temperature of 40 °C to 80 °C or 50 °C to 70 °C. The (optionally filtered) vapor stream is then cooled and at least partially condensed. For example, the vapor stream can be passed through a cooling coil or other heat exchanger, thereby condensing at least a portion of the volatile components from the vapor stream. The vapor stream and any condensed liquid can then be passed to a condensate collection zone, which can include one or more steps operable to remove the condensate from the vapor stream. For example, a first step can include contacting the vapor stream with a baffle or other surface on which the condensate can form and flow downward into a sump positioned at the bottom of the processing system. Other steps can include redirection (e.g., upward) and velocity changes of the vapor stream, which can cause at least a portion of the entrained condensate to separate from the vapor stream and fall into the sump for collection and recovery. Additionally or alternatively, a second cooling step can be utilized to further condense at least a portion of the volatile components remaining in the vapor stream. For example, in some embodiments, the first cooling step can condense 50% to 80% of the volatile components in the vapor stream, while the second cooling step can condense 20% to 50% of the volatile components in the vapor stream. Finally, the vapor stream can optionally be subjected to further filtration, including particulate filtration and / or scrubbing filtration, to recover any remaining condensate in the vapor stream, before the vapor stream is directed through an outlet. The temperature of the vapor stream exiting the system can be 0 °C to 10 °C or 1 °C to 5 °C lower than the temperature of the vapor stream at the inlet. In some embodiments, the recovered condensate can optionally be filtered and stored or recovered for further use. For example, in some embodiments, the condensate includes a blowing agent and / or plasticizer that volatilizes during drying, and the condensed blowing agent and / or plasticizer can be recovered for use in the compounding process described above.

[0024] In one embodiment or in combination with any other embodiment mentioned herein, the dried CE particulate material has a moisture content that is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, or at least 90% lower than the moisture content of the particulate CE material introduced into the drying system. In some embodiments, the dried CE particulate material has a moisture content of no more than 3000 ppm, no more than 2500 ppm, no more than 2000 ppm, no more than 1500 ppm, no more than 1000 ppm, no more than 900 ppm, no more than 800 ppm, no more than 700 ppm, or no more than 600 ppm. In some embodiments, the dried particulate material has a moisture content of from 100 ppm to 5000 ppm, from 200 ppm to 4000 ppm, from 300 ppm to 3000 ppm, from 400 ppm to 2000 ppm, or from 500 ppm to 1000 ppm. The moisture content levels disclosed herein can be measured by one or both of Karl Fischer titration and / or using a moisture measuring device (e.g., aboni HydroTracer).

[0025] In one embodiment or in combination with any other embodiment mentioned herein, at least a portion of the compounded CE material can be packaged for transport and processing in another facility. The compounded CE material can be packaged with or without being subjected to the drying process described above. For example, the fresh compounded CE material can have a moisture content low enough to be packaged immediately before absorbing the moisture content of the environment. Alternatively, the compounded CE material can be dried to a desired moisture content as described above and then packaged. Regardless, the packaged compounded CE material can have a moisture content of no more than 3000 ppm, no more than 2500 ppm, no more than 2000 ppm, no more than 1500 ppm, no more than 1000 ppm, no more than 900 ppm, no more than 800 ppm, no more than 700 ppm, or no more than 600 ppm. In some embodiments, the packaging can be performed by introducing the compounded CE material into a foil-lined (aluminized) bag and sealing it therein.

[0026] The dried compounded CE material as set forth above can include pellets of plasticized biodegradable polymer, which can then be introduced into a foam sheet production method, such as Figure 1 and Figure 2The foam sheet production process can be in the same facility as the compounding process, or the CE material can be shipped to another facility and de-baled therein for further processing in the 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 greater detail below. Although exemplary foam sheet production processes are described herein, it should be understood that certain aspects described herein can also be applicable to rigid (i.e., non-foam) materials and articles. As Figure 1 As shown, in one embodiment or in combination with any other embodiment mentioned herein, various additives can be introduced into one or more zones of the foam sheet production process. The additives can include, but are not limited to, stabilizers, one or more physical blowing agents, one or more chemical blowing agents (and / or precursors), one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0027] 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 into 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 stored into a feed hopper, which introduces the combined feed composition into the extrusion zone. The feed preparation zone can further 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 modification additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0028] The combined feed composition from the feed preparation zone can then be introduced into 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 melted 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. The extrudate can be further shaped by downstream processes as described below.

[0029] One or more additives can be introduced into the CE melted composition while in the extruder. For example, a physical blowing agent can be added to the CE melted composition by injecting the physical blowing agent into the composition being conveyed within the extruder barrel.

[0030] 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 single apparatus. Regardless, the feed composition from the feed preparation zone is introduced into the primary extrusion vessel and at least partially melted as it is conveyed through the extruder barrel as described above, resulting in a CE melted composition. The CE melted composition exiting the primary extrusion vessel can have a temperature of about 220 °C to about 240 °C. One or more additives such as a blowing agent can be added to the CE melted composition as it is conveyed through the primary extrusion vessel.

[0031] The CE melt composition from the primary extrusion vessel can then be introduced into a 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 resin can be further mixed to provide a substantially uniform mixture of the melt polymer and one or more additional additives. The CE melt composition can then be directed through a die and out of a die head to provide a cellulose ester-based extrudate that can be further processed in a sheet forming section of a 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, from about 150°C to about 220°C, and / or from about 170°C to about 200°C.

[0032] As shown in FIG. 1, 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 prior to directing the CE melt composition through the die head to the sheet forming section. Figure 4

[0033] The sheet forming section can include any of a variety of systems and methods for shaping the extrudate into a sheet of cellulose ester material that can be used in article shaping. 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 to 40 cm, 2 to 20 cm, 2 to 10 cm, and / or 3 to 8 cm. Further, the thickness of the opening through which the extrudate is extruded (referred to herein as the “die gap”) can generally be 0.1 to 6.0 mm, 0.1 to 3.0 mm, and / or 0.1 to 1.0 mm.

[0034] Figure 5 An exemplary sheet forming section is depicted in FIG. 2. 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.

[0035] ​A slicing machine (or slitting device) can be used to open the tubular extrudate, which allows the tubular shape to form a flat sheet. For example, a tubular extrudate over a 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 to draw the extrudate onto the mandrel. The flattened extrudate will typically be in the form of a sheet, which can then be directed to a winding station where the material can be wound for packaging and shipping.

[0036] Referring again to Figure 1 and Figure 2 The sheets produced by the sheet production process can be used to form foamed articles, 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, absorption, etc.).

[0037] Compositions

[0038] The above-described methods can include preparing and extruding a composition 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 material 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 blended 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.

[0039] Cellulose ester

[0040] The cellulose ester used as described herein can be any known in the art. The cellulose ester useful in embodiments herein typically comprises repeating units of the following structure:

[0041]

[0042] wherein R1, R2, and R3 are independently selected from hydrogen, acetyl, propyl, or butyl. The level of substitution of cellulose esters is typically expressed in terms of 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 DS can range 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 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. 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 an 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.

[0043] In an 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 at most 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 an 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 an 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, or about 2.0 to about 2.9, or about 2.2 to about 2.8, or 1 to less than 2.2, or 1 to less than 1.5, and the substituting ester is acetyl.

[0044] Cellulose esters can be produced by any method known in the art. Examples of methods for producing cellulose esters are taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th Edition, Volume 5, Wiley-Interscience, New York (2004), pages 394-444. Cellulose is the starting material for producing cellulose esters and can be obtained 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.

[0045] One method of producing cellulose esters is by esterification of cellulose by mixing the cellulose with the 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.

[0046] 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.

[0047] It will be understood by those skilled in the art that the commercial term cellulose triesters also encompasses cellulose esters that are not completely acyl-substituted. 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.

[0048] After esterification of the cellulose to a triester, the acyl substituents can be removed in part by hydrolysis or alcoholysis to give secondary cellulose esters. 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 agent. This method is particularly useful when the reaction is performed in a solvent that dissolves the cellulose. All of these methods result in cellulose esters that can be used in the present application.

[0049] 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.

[0050] 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.

[0051] 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 398-20. TM Cellulose Acetate CA 398-30 and Eastman Cellulose Acetate CA 398-20. TMCellulose acetate CA 398-10, Eastman TM CAP 485-20 Cellulose acetate propionate; Eastman TM CAB 381-2 Cellulose acetate butyrate.

[0052] In an 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 an embodiment or in combination with any other embodiment, such a reactant can be a cellulose reactant, which includes an organic acid and / or an anhydride used in an esterification or acylation reaction of cellulose, e.g., as discussed herein.

[0053] In an 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 dehydrated glucose unit (AU) derived from a recycled content material (e.g., a recycled plastic content syngas).

[0054] In an embodiment or in combination with any other embodiment, the cellulose ester composition comprises cellulose ester in an amount of 50 to 99 wt%, or 60 to 99 wt%, or 70 to 99 wt%, or 80 to 99 wt%, from 50 to 98 wt%, or 60 to 98 wt%, or 70 to 98 wt%, or 80 to 98 wt%, or 90 to 98 wt%, 50 to 90 wt%, or 60 to 90 wt%, or 70 to 90 wt%, or 80 to 90 wt%, or 90 to 99 wt%, or 50 to 80 wt%, or 60 to 80 wt%, or 70 to 80 wt%, or 50 to 70 wt%, or 60 to 70 wt%, or 50 to 60 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein 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 composed of a blend of two or more cellulose esters having different DSAC; however, the blend can have a total DSAC of between 2.2 and 2.8 or a total DSAC of between 2.0 and 2.9.

[0055] Plasticizer

[0056] 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 (triacetyl), diacetin (diacetyl), 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- epoxypropylphenyl 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 poly(alkyl succinate) such as poly(butyl succinate), polyether sulfone, o-tolyl p-toluenesulfonate, N-ethyl toluene sulfonamide, adipate-based plasticizers, soybean oil epoxide such as Paraplex TM plasticizer series, sucrose-based plasticizers, dibutyl sebacate, glycerol tributyrate, sucrose acetate isobutyrate, Resolflex TM plasticizer series, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolate esters (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 include a combination or mixture of two or more different types of plasticizers.

[0057] 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.

[0058] In an embodiment, or in combination with any other embodiment, the plasticizer is a food compliant plasticizer. Food compliant means compliance with applicable food additive and / or food contact regulations, where the plasticizer is approved for use or considered 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 Generally Recognized as Safe (GRAS) by the U.S. FDA. In an 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 an 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 glycol succinate, diisobutyl adipate, polyvinyl pyrrolidone, and tribenzoin diol ester.

[0059] In an embodiment, or in combination with any other embodiment, the plasticizer is present in an amount sufficient to allow the cellulose ester composition to be melt processed (or thermoformed) into useful articles, such as disposable plastic articles, in conventional melt processing equipment. In an embodiment, or in combination with any other embodiment, the plasticizer is present in an amount of 1 to 40 wt%, or 5 to 25 wt%, or 10 to 25 wt%, or 12 to 20 wt%, based on the weight of the cellulose ester composition, 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 10-30, or 12-25, or 15-20, or 10-25 wt%, based on the weight of the cellulose ester composition.

[0060] 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 TM plasticizer series, poly(alkyl succinate)s such as poly(butyl succinate), polyether sulfone, adipate-based plasticizers, soybean oil epoxide such as Paraplex TM plasticizer series, sucrose-based plasticizers, dibutyl sebacate, glycerol tributyrate, ResoflexTM a series of plasticizers, triphenyl phosphate, glycolate esters, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diyl bis(2-methylpropanoate), and polycaprolactone.

[0061] In an embodiment, or in combination with any other embodiment, the cellulose ester composition can contain a plasticizer selected from PEG and MPEG (methoxyl PEG). The polyethylene glycol or methoxyl polyethylene glycol composition has an average molecular weight of 200 to 600 daltons, wherein the composition is melt processable, biodegradable, and disintegrable.

[0062] In an embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol or methoxyl PEG having an average molecular weight of 300 to 550 daltons.

[0063] 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.

[0064] In an embodiment, or in combination with any other embodiment, the cellulose ester composition comprises at least one plasticizer (as described herein) in an amount of 1 to 40 wt%, or 5 to 40 wt%, or 10 to 40 wt%, or 12 to 40 wt%, 13 to 40 wt%, or 15 to 40 wt%, or greater than 15 to 40 wt%, or 17 to 40 wt%, or 20 to 40 wt%, or 25 to 40 wt%, or 5 to 35 wt%, or 10 to 35 wt%, or 13 to 35 wt%, or 15 to 35 wt%, or greater than 15 to 35 wt%, or 17 to 35 wt%, or 20 to 35 wt%, or 5 to 30 wt%, or 10 to 30 wt%, or 13 to 30 wt%, or 15 to 30 wt%, or greater than 15 to 30 wt%, or 17 to 30 wt%, or 5 to 25 wt%, or 10 to 25 wt%, or 13 to 25 wt%, or 15 to 25 wt%, or greater than 15 to 25 wt%, or 17 to 25 wt%, or 5 to 20 wt%, or 10 to 20 wt%, or 13 to 20 wt%, or 15 to 20 wt%, or greater than 15 to 20 wt%, or 17 to 20 wt%, or 5 to 17 wt%, or 10 to 17 wt%, or 13 to 17 wt%, or 15 to 17 wt%, or greater than 15 to 17 wt%, or 5 to less than 17 wt%, or 10 to less than 17 wt%, or 13 to less than 17 wt%, or 15 to less than 17 wt%, all based on the total weight of the cellulose ester composition.

[0065] In one embodiment or in combination with any other embodiment, the at least one plasticizer includes or is a food-compliant or FDA-approved plasticizer. In one embodiment or in combination with any other embodiment, the food-compliant or FDA-approved plasticizer includes or is triacetin or PEG MW 300 to 500.

[0066] Biodegradable polymer

[0067] In one embodiment or in combination with any other embodiment described herein, 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 mentioned herein, 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 mentioned herein, 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 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.

[0068] Nucleating agent

[0069] Nucleating agent means a chemical or physical material that provides sites for cell formation 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 foam sheet production process. For example, the nucleating agent can be blended with the formulation introduced into the extruder hopper 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 the extrusion process (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.

[0070] Suitable physical nucleating agents 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 physical nucleating agent will have an average particle size of less than 1000 microns, less than 500 microns, less than 100 microns, less than 50 microns, less than 25 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 2 microns, less than 1.5 microns, and / or less than 1.0 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 physical nucleating agent should have a melting temperature of at least 220°C, at least 230°C, at least 240°C, at least 250°C, at least 275°C, at least 300°C, at least 325°C, or at least 350°C. However, the physical nucleating agent can be selected such that it has the ability to recrystallize upon cooling after melting.

[0071] 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.

[0072] 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.

[0073] 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 or other type of blowing agent. In some embodiments, the precursors are configured to form a gas such as CO2or N2during the extrusion of the particulate material.

[0074] 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 (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, 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 polyesters, 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 make up about half (wt%) of the chemical nucleating agent, while the carrier makes up 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.

[0075] In one embodiment or in combination with any of the embodiments mentioned herein, the nucleating agent is present in an amount of 0.1 to 10 wt%, 0.1 to 5.0 wt%, at least 0.1 wt%, at least 0.25 wt%, at least 0.5 wt% at least 1.0 wt%, at least 1.25 wt%, at least 1.5 wt%, at least 1.75 wt%, at least 2.0 wt%, at least 2.25 wt%, at least 2.5 wt%, at least 2.75 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt% and / or less than 7.5 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agent used herein can comprise a combination or mixture of two or more different types of nucleating agents. In one embodiment or in combination with any other embodiment, the CE melt composition comprises less than 10 wt%, less than 8 wt%, less than 6 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 wt% of talc.

[0076] Note that regardless of whether in the form of a compounded CE material or a CE melt composition, the cellulose ester material is generally capable of accepting a maximum amount of nucleating agents that can function to form nucleation sites. Any remaining nucleating agents added to the cellulose ester material will remain as fillers. Based on the type of filler used, the fillers 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 (e.g., color, opacity, etc.) and tactile (e.g., material continuity, surface roughness, etc.) characteristics of the cellulose ester material.

[0077] Blowing agent

[0078] Blowing agent refers to a physical or chemical material (or combination of materials) used to expand the 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 function 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. It has been surprisingly discovered that the hygroscopic properties of the biodegradable microparticle natural filler allow them to absorb moisture and bring the absorbed water into the melt resin mixture, where the water can act as a physical blowing agent.

[0079] Examples of physical blowing agents include H2O, N2, CO2, alkanes, alkenes, ethers, ketones, argon, helium, air, or mixtures. Additionally, it has been surprisingly discovered that the hygroscopic properties of the biodegradable microparticle natural filler allow them to absorb moisture and bring the absorbed water into the melt resin mixture, where the water can act as a physical blowing agent. The hygroscopic biodegradable natural filler can be formulated into a composition and allowed to absorb moisture prior to the foaming process, which then releases the water to act as a physical blowing agent during the foaming process. Beneficially, the 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.

[0080] 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.

[0081] In one embodiment or in combination with any of the embodiments mentioned herein, the blowing agent is present in an amount of 0.3 to 1.5 wt%, or 0.3 to 2.0 wt%, or 0.3 to 2.5 wt%, or 0.3 to 3.0 wt%, or 0.3 to 3.5 wt%, or 0.3 to 4.0 wt%, or 0.3 to 8%, or 1.3 to 1.5 wt%, or 1.3 to 2.0 wt%, or 1.3 to 2.5 wt%, or 1.3 to 3.0 wt%, or 1.3 to 3.5 wt%, or 1.3 to 4.0 wt%, or 1.3 to 4.5 wt%, or 1.3 to 5.0 wt%, or 1.3 to 5.5 wt%, or 1.5 to 3.0 wt%, or 1.5 to 4.0 wt%, or 1.5 to 5.0 wt%, or 1.5 to 6.0 wt%, or 2.0 to 3.0 wt%, or 2.0 to 4.0 wt%, or 2.0 to 5.0 wt%, or 2.0 to 6.0 wt%, or 2.5 to 3.0 wt%, or 2.5 to 4.0 wt%, or 2.5 to 5.0 wt%, or 2.5 to 6.0 wt%, or 3.0 to 4.0 wt%, or 3.0 to 5.0 wt%, or 3.0 to 6.0 wt%, or 0.0 to 9.0 wt%, or 0.5 to 9.0 wt%, or 1.0 to 9.0 wt%, or 1.5 to 9.0 wt%, or 2.0 to 9.0 wt%, or 2.5 to 9.0 wt%, or 3.0 to 9.0 wt%, or 3.5 to 9.0 wt%, or 4.0 to 9.0 wt%, or 4.5 to 9.0 wt%, or 5.0 to 9.0 wt%, or 5.5 to 9.0 wt%, or 6.0 to 9.0 wt%, or 6.5 to 9.0 wt%, or 7.0 to 9.0 wt%, or 7.5 to 9.0 wt%, or 8.0 to 9.0 wt%, or 8.5 to 9.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the blowing agent used herein can comprise a combination or mixture of two or more different types of blowing agents.

[0082] Surface modification additives

[0083] Surface modifying additives are materials that can be added to a cellulose ester composition to modify 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 found that adding a surface modifying additive to a compounded CE material (e.g., added to the pellets during compounding) or to a CE melt composition (e.g., during extrusion) can improve processing by reducing undesirable adhesion of the CE melt composition to the die or mandrel (or other components of the foam sheet production process). This reduction in adhesion can be achieved by the surface modifying additive inhibiting the fusion of the cellulose ester caused by the plasticizer. Adding a surface modifying additive can also reduce the blocking of cellulose ester foam sheet produced in the sheet forming section. In addition, a surface modifying additive can also improve the foam sheet production process by allowing the process to be run at lower temperatures.

[0084] Furthermore, in some embodiments, the surface modifying additive can function 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 a hydrocarbon is used as a blowing agent in order to reduce the chance of igniting the hydrocarbon and causing a fire. Beneficially, the surface modifying additive can also reduce the outward diffusion of blowing agents such as hydrocarbons from the foam sheet or resulting article. In some embodiments, the hydrocarbon itself can be used as the surface modifying additive.

[0085] More general examples of surface modifying additives that can be used in accordance with embodiments of the present application to a compounded CE material (e.g., during compounding) or to a CE melt composition (e.g., in a foam sheet production process) include fatty acids such as palmitic acid, tallow acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, arachidic acid / behenic acid, behenic acid, and erucic acid. Surface modifying additives can also include fatty acid amides such as erucamide, oleamide, stearamide, behenamide, secondary amides, and bis-amides.

[0086] The other example of surface modification additive can include glyceride and / or stearate, such as monoglyceride, diglyceride and triglyceride.Monoglyceride can include glyceryl monostearate or monoglyceride derivatives, such as diacetyl tartaric acid ester (DATEM), ethoxylated monoglyceride, succinyl monoglyceride and propylene glycol monoester (PGME) of monoglyceride and diglyceride.The example of surface modification additive can also include metal stearate, such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate and / or their combination (for example, calcium stearate / zinc stearate).The example of surface modification additive can also include wax, such as polyolefin wax (polypropylene wax and polyethylene wax), oxidized olefin wax, ethylene acrylic acid (EAA) copolymer wax, ethylene methyl acrylate (EMA) copolymer wax, EAA ionomer wax, acrylic acid wax and / or natural wax, such as rice bran wax, sunflower wax, sugarcane wax, candelilla wax, soybean wax, beeswax, candelilla wax and carnauba wax.

[0087] Other non-exclusive examples of surface modification additives include aliphatic diesters (for example, dioctyl adipate), polyglycol diesters, alkyl alkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters and alkyl monoesters. In addition, various oils can be used as surface modification additives, such as aromatic oils, naphthenic oils, glyceride oils, silicone oils and epoxidized oils (for example, soybean oil and linseed oil). Therefore, in some embodiments, surface modification additives include plasticizers, such as aliphatic diester plasticizers, polyester plasticizers etc. In addition, in some embodiments, surface modification additives can include polyhedral oligomeric silsesquioxanes (POSS).

[0088] More generally, the surface modification additives used in embodiments of the present invention can have a lower polarity than the cellulose ester in the compounded CE material (e.g., during compounding) or the CE melt composition (e.g., during foam sheet production). For example, the surface modification additive can have (based on the Hansen solubility parameter): less than 25 MPa 1 / 2 , less than 20MPa 1 / 2 , or less than 19.5MPa 1 / 2 Total solubility parameter δ; less than 18MPa 1 / 2 , less than 16MPa 1 / 2 , or less than 14MPa 1 / 2 The dispersion solubility parameter δ d Less than 12MPa 1 / 2 , less than 8MPa 1 / 2 , or less than 4MPa 1 / 2 Solubility parameter δ of the dipole intermolecular force d ; and / or less than 11MPa1 / 2 less than 10 MPa 1 / 2 or less than 9 MPa 1 / 2 hydrogen bonding solubility parameter δ h However, in some other embodiments, the surface modification additive used in embodiments of the present application can be more polar than the cellulose ester in the compounded CE material (e.g., during compounding) or the CE melt composition (e.g., during foam sheet production). For example, the surface modification additive can have (based on Hansen solubility parameters): a total solubility parameter δ of 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 modification additive can have a boiling point of greater than 200 °C, greater than 220 °C, greater than 240 °C, greater than 260 °C, greater than 280 °C, or greater than 300 °C. Furthermore, the surface modification additive can have a molecular weight of 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 modification additive is not soluble in the plasticizer(s) used in the cellulose ester composition. For example, it can be preferred that the surface modification additive is not soluble in triacetin. Finally, in some embodiments, the surface modification additive can be biodegradable and / or food compliant or FDA approved.

[0089] In one embodiment or in combination with any of the embodiments mentioned herein, the surface modification additive is present in an amount of 0.05 to 0.75 wt%, or 0.05 to 1.0 wt%, or 0.05 to 2.5 wt%, or 0.05 to 5.0 wt%, or 0.75 to 1.0 wt%, or 0.75 to 2.5 wt%, or 0.75 to 5.0 wt%, or 0.1 to 1.0 wt%, or 0.1 to 2.5 wt%, 0.1 to 5.0 wt%, or 1.0 to 2.5 wt%, or 1.0 to 5.0 wt%, or 2.5 to 5.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the surface modification additive used herein can comprise a combination or mixture of two or more different types of surface modification additives.

[0090] Article of manufacture

[0091] Extruded sheets of cellulose ester foam can be formed using the extrusion and / or sheet forming sections described above. Such extruded sheets comprise a structural material having a plurality of gas voids dispersed throughout. Such gas voids are formed by expansion of a blowing agent in the form of a gas in the 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.).

[0092] In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.20 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.18 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.15 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.12 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.10 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.08 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.06 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of less than 0.04 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.8 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.6 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.5 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.4 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.3 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.2 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.15 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.12 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.10 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.08 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.04 to 0.06 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.8 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.6 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.5 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.4 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.3 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.2 g / cm3 3 In one embodiment or in combination with any of the embodiments mentioned herein, the foam has a density of 0.06 to 0.15 g / cm33 0.06 to 0.12 g / cm 3 0.06 to 0.10 g / cm 3 0.06 to 0.08 g / cm 3 0.08 to 0.8 g / cm 3 0.08 to 0.6 g / cm 3 0.08 to 0.5 g / cm 3 0.08 to 0.4 g / cm 3 0.08 to 0.3 g / cm 3 0.08 to 0.2 g / cm 3 0.08 to 0.15 g / cm 3 0.08 to 0.12 g / cm 3 0.08 to 0.10 g / cm 3 0.1 to 0.8 g / cm 3 0.1 to 0.6 g / cm 3 0.1 to 0.5 g / cm 3 0.1 to 0.4 g / cm 3 0.1 to 0.3 g / cm 3 0.1 to 0.2 g / cm 3 0.1 to 0.15 g / cm 3 0.1 to 0.12 g / cm 3 0.2 to 0.8 g / cm 3 0.2 to 0.6 g / cm 3 0.2 to 0.5 g / cm 3 0.2 to 0.4 g / cm 3 0.2 to 0.3 g / cm 3 0.3 to 0.6 g / cm 3 0.3 to 0.5 g / cm 3 0.3 to 0.4 g / cm 3 0.4 to 0.6 g / cm 3 0.4 to 0.5 g / cm 3 or 0.5 to 0.6 g / cm 3 density.

[0093] 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.

[0094] The moisture content of the particulate CE material used in the above-described methods can have a significant impact on the properties of the resulting foam article. Such properties can include open cell content, average cell size, maximum cell size, cell density, and cell size uniformity. Cell density can be determined by the number of observable cells in a cross-sectional area of a center side plane of the foam article. Cell size uniformity can be determined by a span factor of the foam article, which can be calculated by the formula (D90-D10) / D50, where “D10” refers to the cell diameter at which 10% of the distribution has a smaller cell size and 90% has a larger cell size, where “D90” refers to the cell diameter at which 90% of the distribution has a smaller cell size and 10% has a larger cell size, and where “D50” refers to the cell diameter at which 50% of the distribution has a smaller cell size and 50% has a larger cell size.

[0095] In one embodiment or in combination with any of the embodiments mentioned herein, when a particulate CE material having a moisture content of 200 ppm to 5000 ppm or 500 ppm to 3000 ppm is introduced into a foam sheet extrusion process, the resulting foam sheet can have one or more of the following: (i) an open cell content of less than 15%, less than 12%, less than 10%, less than 8%, or less than 6%; (ii) an average cell size of less than 500 pm, less than 400 pm, or less than 300 pm; (iii) a maximum cell size of less than 800 pm, less than 700 pm, or less than 600 pm; (iv) 100 to 3000, 200 to 2000, 300 to 1500, 400 to 1000, 500 to 800, or 600 to 700 cells / cm2; (v) a span factor of less than 2.0, less than 1.8, less than 1.6, less than 1.4, or less than 1.2; or (vi) a density of less than 0.50 g / cm3, less than 0.45 g / cm3, less than 0.40 g / cm3, less than 0.35 g / cm3, or less than 0.30 g / cm3. 2(v) a surface roughness R of less than 50 μm, less than 40 μm, or less than 30 μm rms and / or (vi) a cell span factor of no more than 1.25, no more than 1.2, no more than 1.1, no more than 1.0, no more than 0.9, no more than 0.8, or no more than 0.75.

[0096] In one embodiment or combination with any embodiment mentioned herein, when a particulate CE material having a moisture content of 5000 ppm to 20,000 ppm is introduced into a foam sheet extrusion process, the resulting foam sheet can have one or more of the following: (i) an open cell content of at least 10%, at least 15%, or at least 20%; (ii) an average cell size of at least 500 μm, at least 550 μm, or at least 600 μm; (iii) a maximum cell size of at least 800 μm, at least 900 μm, or at least 1000 μm; (iv) less than 400 cells / cm 2 , less than 300 cells / cm 2 , less than 200 cells / cm 2 , less than 100 cells / cm 2 , or less than 50 cells / cm 2 (v) a surface roughness R of at least 50 μm, at least 60 μm, or at least 70 μm rms and / or (vi) a cell span factor greater than 0.75, greater than 0.8, greater than 0.9, greater than 1.0, greater than 1.1, greater than 1.2, or greater than 1.25.

[0097] Further inventive concepts relate to methods and systems for producing pellets, foam sheets and / or articles.

[0098] The embodiments described herein are particularly useful in producing cellulose ester foam sheets and articles, although the embodiments may also be used in other sheet and article production applications.

[0099] In one embodiment or in combination with any of the embodiments mentioned herein, an industrially compostable or home compostable biodegradable cellulose acetate foam or article can be produced. In one subcategory of this class, the foam or article is industrially compostable. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 6 mm. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 3 mm. In one sub-subcategory of this subcategory, the article has a thickness of less than 1.1 mm. In one subcategory of this class, the foam or article is home compostable. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 6 mm. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 3 mm. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 1.1 mm. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 0.8 mm. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 0.6 mm. In one sub-subcategory of this subcategory, the foam or article has a thickness of less than 0.4 mm.

[0100] In one embodiment or in combination with any of the embodiments mentioned herein, the foam or article has a thickness of 1 to 10 mm, 1 to 8 mm, 2 to 8 mm, 3 to 7 mm, 4 to 6 mm, about 4 mm, about 5 mm, 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 to 24 inches, 1 to 15 inches, or 3 to 12 inches. Alternatively or additionally, the tray or other article can have a thickness (i.e., thickness of the cellulose ester foam material) of 100-400 mils, 120-300 mils, 150-250 mils.

[0101] In one embodiment or in combination with any of the embodiments mentioned herein, the foam or article exhibits greater than 90% disintegration after 12 weeks according to the disintegration test protocol as described in the specification.

[0102] The composition for making a 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, antifungals, heat stabilizers, antibacterials, softeners, mold release agents, UV absorbers, and combinations thereof. Each additional additive can be present in the cellulose ester-based material in an amount of less than 10 wt.%, less than 5 wt.%, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, or less than 1.0 wt.%. It should be noted that the same type of compound or material can be identified in or included in multiple groupings for cellulose acetate compositions. 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 lower molecular weight PEG has a plasticizing effect, while higher molecular weight PEG functions as a hydrophilic polymer but not as a plasticizer.

[0103] 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.

[0104] In an 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 particulate natural filler.

[0105] Definitions

[0106] It should be understood that the following is not intended to be an exhaustive list of defined terms. Other definitions can be provided in the foregoing description, such as, for example, in the use of the defined terms in the context in which they are presented.

[0107] As used herein, the terms “a,” “an,” and “the” mean one or more.

[0108] As used herein, the terms“comprising,”“comprises” and“comprise,” are open-ended transitional phrases used to transition from a preceding clause to one or more elements listed in the clause that follows each respective transitional phrase, wherein the one or more elements listed after the transitional phrase are not necessarily the only elements constituting the subject matter.

[0109] 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 a control polymer; (2) the material tested under aerobic composting conditions must achieve a 90% degree of disintegration according to ISO 16929 (2013); (3) the test material must meet all requirements for 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.

[0110] As used herein, the term“biodegradable” generally refers to the biological conversion and consumption of organic molecules. 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 down 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 impact of a material on plant life, and the heavy metal content of a material is determined according to procedures specified in standard test methods.

[0111] To be considered“biodegradable” under home composting conditions 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 at least 90% of the maximum degradation of the appropriate reference material after both the reference and test articles have reached the plateau phase. The maximum test duration for biodegradation under home composting conditions is 1 year.

[0112] To be considered "biodegradable" under industrial composting conditions 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 by the end of the test period when compared to a control or absolute value. According to European Standard ED 13432 (2000), a material must exhibit a total biodegradation of at least 90%, or at least 90% of the maximum degradation of a suitable reference material after both the reference and test items have reached the stationary phase. The maximum test duration for biodegradability under industrial composting conditions is 180 days.

[0113] According to The OK Biodegradable Soil Compostable Mark of the German Society for the

[0114] The claims are not limited to the disclosed embodiments

[0115] The above preferred forms of the invention will serve only as illustrations and should not be construed as limiting the scope of the invention in any manner. Those skilled in the art could readily make modifications to the exemplary embodiments set forth above without departing from the spirit of the invention.

[0116] The inventors hereby declare that they intend to determine and evaluate the reasonable and fair range of equivalents to the present invention in accordance with the doctrine of equivalents, as it is interpreted when it involves any apparatus not materially departing from but outside the literal scope of the present invention as set forth in the following claims.

[0117] Experimental Section

[0118] Abbreviations

[0119] h is hour; Tg is glass transition temperature; °C is degrees Celsius;

[0120] Moisture was measured by Karl Fisher method using 1.5 gram samples and a temperature of 180 °C, followed by titration to determine moisture levels. The following samples were dried at 60 °C for the listed duration. The Karl Fisher testing process for solid materials used a Metrohm 874 Oven Sample Processor and a coulometric KF cell. Each sample was weighed (0.5-1.0 g) and placed into a 5 ml vial and capped. Each sample set included 3 empty vials as atmospheric blanks; these samples were prepared at the same time and place as the samples were sealed in their vials. The oven sample processor heated each sample to a target temperature of 180 c. Nitrogen gas was used as a carrier gas to bring any moisture released by the sample at temperature into the coulometric analysis cell for titration. Results were calculated by the following equation:

[0121]

[0122] Table 1. Drying of CE Resin.

[0123]

[0124] Formulated cellulose acetate can be dried by desiccant drying systems manufactured for drying other polymers. Desiccant drying systems tend to have problems when the polymer absorbs more than 1 wt% moisture because the desiccant becomes saturated with moisture and the bed cannot regenerate quickly enough to keep the dew point from rising. If the dew point rises, the drying becomes less efficient and the drying rate tends to slow and the moisture loss tends to slow or stop. Methods have been designed to avoid this situation, including a hot air process. For the hot air process, air is heated and passed through the pellets and the volatiles are vented out of the process. For the hot air process, the drying is not closed loop and excess moisture is vented out of the process. Once the moisture content is driven to less than 1 wt%, the desiccant drying process can be used to drive the moisture content to even lower levels.

[0125] The desiccant drying process involves using hot air to dry the pellets (50 °C to 70 °C) and a closed loop system with a post-cooler and a volatiles trap. The volatiles trap is designed to use cooler water than room temperature to extract any volatiles (e.g., processing aids / plasticizers) that can change the desiccant bed.

[0126] The base formulation was cellulose acetate with a DS of 2.5. The polymer was plasticized with triacetin, polyethylene glycol, or triethyl citrate at the following target levels.

[0127] Table 2. Drying Temperatures.

[0128]

[0129] The following samples were measured for moisture using an Aboni Hydrotracer, where the evaporated water reacts with calcium hydride. The water is then converted to hydrogen gas, which is then used to determine the water concentration.

[0130] Pore analysis plays a crucial role in the evaluation of foam materials. In our approach, we utilize SEM image analysis of foam sections to assess the porosity. To address the challenges posed by the amorphous nature of the pores and potentially ambiguous or broken boundaries, we developed a fully automated porosity evaluation method that combines three key image processing techniques. First, an intensity threshold is applied to separate the darker pore bodies from the cell walls. Second, edge detection is employed to capture the edges between adjacent pores, thereby refining the segmentation. Finally, a watershed algorithm is utilized to accurately separate the conjoined pores by simulating the flooding of water from different directions into adjacent regions. By combining these techniques, our automated method achieves improved segmentation, thereby enhancing the statistical representativeness and accuracy of the pore size analysis. This integrated approach provides valuable insights into the porosity characteristics of foam materials, facilitating the design of foam products with enhanced properties.

[0131] The formulation for making the foam sheet was as follows: cellulose acetate formulation [Eastman Cellulose Acetate FE700, triacetin (20 wt%), epoxidized soybean oil (1 wt%) doverphos 9228T (0.15 wt%)] + 1 wt% CBA (Foamazol 73S) + 1 wt% talc + 2.3 wt% pentane.

[0132] The foam sheet was manufactured on a tandem extrusion line. The first extruder was a twin screw ZE 30 manufactured by Krauss Maffei. The 2nd extruder was a single screw KE60 also manufactured by Krauss Maffei. The physical blowing agent (pentane) was injected in the barrel zone 4 of the twin screw extruder. The foam was extruded at 40 kg / hour, the ZE30 was set at a zone temperature of 190°C to 220°C to melt the polymer and inject the gas, and the cooling extruder (KE60) temperature was 170°C to 190°C. The material was extruded over a core of 160 mm diameter, resulting in a blow up ratio of 3.2x the die diameter.

[0133] The foam sheet exhibited a medium level of corrugation when the moisture content was 10,000 ppm and a high level of corrugation when the moisture content was above 20,000 ppm. Acceptable corrugation was below 10000 and was slight, and corrugation below 1000 ppm was non-existent. Thicknesses of 4 mm or more could not be achieved when the moisture content was above 20,000 ppm.

[0134] All foams produced had a density below 0.12 g / cm 3 .

[0135] Table 3. Foam quality as a function of moisture content.

[0136]

[0137] Table 4. Foam quality as a function of moisture content.

[0138]

[0139] The material was packaged from the production line in foil lined bags and moisture samples were tested. Moisture was analyzed using an OmniMark moisture analyzer which monitors weight loss over time to calculate moisture loss. The program for the instrument had a stand-by temperature of 40°C, a test temperature of 105°C, and monitored rate loss to determine when the test was complete. The test program had a variable rate of 0.035% / 1 min and the test product was run until the slope criteria was met.

[0140] Each sample reported below was a batch of 10 to 30 boxes depending on the run. The moisture content reported is the average of the boxes measured as part of the batch.

[0141] Table 5.

[0142]

Claims

1. A method of forming a dry particulate material, the method comprising: (a) providing an expandable microparticle composition comprising a cellulose ester and a plasticizer, the expandable microparticle composition having a moisture content; as well as (b) introducing said expandable particulate composition into a drying system, thereby reducing said moisture content and forming said dry particulate material, wherein the drying system comprises contacting the composition with a drying vapor stream passing through the drying system, wherein the drying vapor stream is discharged until the moisture content is 1 wt% or less, wherein the drying vapor stream is air, wherein the expandable microparticle composition is dried in the drying system at a temperature at least 60°C below the Tg of the composition, but not more than 80°C, not more than 70°C, or not more than 60°C.

2. The method of claim 1 , wherein said introducing (b) further comprises drying said expandable particulate composition by circulating said drying vapor stream through a closed loop desiccant drying system after the moisture content of said expandable particulate composition has reached 1 wt % or less.

3. The method according to any one of claims 1 or 2, wherein the initial moisture content is 8 wt% or less or 6 wt% or less.

4. The method of any one of claims 1 to 3, further comprising cooling and at least partially condensing a portion of the drying vapor stream to form a condensate comprising volatile components entrained in the drying vapor stream.

5. The method according to claim 4, wherein the condensate comprises a blowing agent and / or a plasticizer.

6. The method of claim 5, further comprising recycling at least a portion of the blowing agent and / or plasticizer into the composition upstream of the drying system.

7. The method according to any one of claims 1 to 6, wherein the drying system comprises a heating process, an air drying process and / or a cyclone drying process.

8. The method of any one of claims 1 to 7, wherein the dry particulate material has a moisture content of 100 ppm to 5000 ppm, 200 ppm to 4000 ppm, 300 ppm to 3000 ppm, 400 ppm to 2000 ppm, or 500 ppm to 1000 ppm as measured by one or both of Karl Fischer titration and / or determination of absolute water content using a moisture measuring device.

9. The method of any one of claims 1 to 8, wherein the dry particulate material has a moisture content that is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, or at least 90% lower than the moisture content of the foamable particulate composition.

10. The method of any one of claims 1 to 9, wherein the plasticizer is triacetin, poly(ethylene glycol) having a molecular weight of 200-600, triethyl citrate, or a mixture thereof.

11. The method of any one of claims 1 to 9, wherein the composition further comprises a stabilizer, 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.

12. The method of any one of claims 1-11, wherein the cellulose ester is cellulose acetate having a degree of substitution ("DSAc") of acetyl substituents of 2.2 to 2.

8.

13. A particulate material prepared by a method according to any one of claims 1 to 12, wherein the particulate material has a moisture content of no more than 2000 ppm as measured by one or both of Karl Fischer titration and / or determination of absolute water content using a moisture measuring device.

14. A method for forming a foam sheet, the method comprising: A particulate material comprising cellulose ester and having a moisture content of 200 ppm to 5000 ppm is introduced into a foam sheet extrusion process and produces a foam sheet having one or more of the following: (i) an open cell content of less than 15%; (ii) an average cell size of less than 500 microns; (iii) a maximum cell size of less than 800 microns; (iv) 100 to 3000 cells / cm 2 Cell density; (v) Surface roughness R less than 50 μm rms and / or (vi) A cell span factor not exceeding 1.

25.

15. The foam sheet forming method according to claim 14, comprising: A particulate material comprising cellulose ester and having a moisture content of 200 ppm to 5000 ppm is introduced into a foam sheet extrusion process and produces a foam sheet having: (i) an open cell content of less than 10%; (ii) an average cell size of less than 500 microns; (iii) Surface roughness R of 4.7-10.5 rms ;as well as (iv) a cell span factor not exceeding 1.

25.

16. The foam sheet forming method according to claim 15, wherein the foam sheet has 5,000 to 17,000 cells / cm 2 The cell density.

17. A method of packaging particulate material, the method comprising: (a) providing an expandable microparticle composition comprising a cellulose ester and a plasticizer and having a moisture content of not more than 3000 ppm; as well as (b) introducing the microparticle composition into a moisture-proof package and sealing the composition therein.

18. The method of claim 17, wherein the moisture barrier packaging comprises a foil-lined bag.

19. The method of any one of claims 17-18, wherein the expandable particulate composition is treated with a drying system comprising contacting the expandable particulate composition with a drying vapor stream passing through the drying system, wherein the drying vapor stream is discharged until the moisture content is 1 wt% or less.

20. The method of claim 19, wherein the expandable microparticle composition is dried in the drying system at a temperature at least 60°C below the Tg of the composition, but not more than 100°C, not more than 90°C, not more than 80°C, not more than 70°C, or not more than 60°C.

21. The method of any one of claims 17-20, further comprising drying the expandable particulate composition after the moisture content of the expandable particulate composition has reached 1 wt% or less by circulating the drying vapor stream through a closed loop desiccant drying system.

22. The method of any one of claims 17 to 21, wherein the dry particulate material has a moisture content of 100 ppm to 5000 ppm, 200 ppm to 4000 ppm, 300 ppm to 3000 ppm, 400 ppm to 2000 ppm, or 500 ppm to 1000 ppm as measured by one or both of Karl Fischer titration and / or determination of absolute water content using a moisture measuring device.

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