Cellulose ester particles with reduced moisture content for foam sheet manufacturing processes

Abstract

The cellulose ester pellets have reduced moisture content for producing cellulose ester foam articles. The pellets can be dried after compounding, so that the pellets are introduced into the extruder with a lower moisture content than in conventional processes. The pellets can be optionally dried after compounding and then packaged, thereby providing a pelletized cellulose ester product with a low moisture content. High-moisture pellets can also be used to achieve the desired foam article properties.

Description

[Background technology]

[0001] Many foamed products, such as food packaging, are disposable items intended to be discarded after use. One commercially important material used to manufacture foamed products is polystyrene. However, polystyrene is neither compostable nor biodegradable. Furthermore, some municipalities, states, and countries have implemented or are considering implementing bans on the use of polystyrene-based foams. Therefore, it is desirable to find alternative materials for use in foamed products, as well as promising compositions, methods, and systems for manufacturing such products.

[0002] Furthermore, pellets for use in making foamed products typically have moisture levels that can produce foam with unacceptable cell size and quality. Therefore, it would be desirable to find alternative systems and methods for producing and utilizing particulates with moisture levels that produce acceptable foamed products. Summary of the Invention

[0003] In one embodiment, or in combination with any other embodiment described herein, there is provided a foamable composition for use in a foam sheeting process, the composition comprising dry cellulose ester microparticles having a moisture content of 2000 ppm or less, as measured by one or both of Karl Fischer titration and / or the use of a moisture measuring device to determine absolute moisture content.

[0004] In another embodiment, or in combination with any other embodiment described herein, there is provided a method of forming a dry particulate material, the method including: (a) providing an expandable particulate composition including a cellulose ester and a plasticizer, the expandable particulate composition having a moisture content; and (b) introducing the expandable particulate composition into a drying system, thereby reducing the moisture content and forming a dry particulate material.

[0005] In another embodiment, or in combination with any other embodiment described herein, there is provided a foam sheet forming process, comprising introducing a particulate material comprising a cellulose ester and having a moisture content of 200 ppm to 5000 ppm into a foam sheet extrusion process, and forming a foam sheet having (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, and (iv) a cell size of less than 1 cm. 2 (v) a cell density of 100 to 3000 cells per cell; (v) a surface roughness R of less than 50 microns rms and / or (vi) a cell span factor of 1.25 or less.

[0006] In another embodiment, or in combination with any other embodiment described herein, there is provided a foam sheet forming process, comprising: introducing a particulate material comprising a cellulose ester and having a moisture content of 5000 ppm to 20,000 ppm into a foam sheet extrusion process; and forming a foam sheet having (i) an open cell content of at least 10%, (ii) an average cell size of at least 500 microns, (iii) a maximum cell size of at least 800 microns, and (iv) a cell size of at least 1 cm. 2 (v) a surface roughness R of at least 50 microns; rms and / or (vi) producing a foamed sheet having one or more of: (i) a cell span factor of greater than 0.75.

[0007] In another embodiment, or in combination with any other embodiment described herein, there is provided a foam sheet forming process. The process comprises a cellulose ester having a moisture content of more than 10,000 ppm and 2 to 10 wt. % (C 4-6 ) introducing a particulate material comprising an alkane, less than 5% by weight of talc, and 0.1 to 2% by weight 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 of less than 20 microns. rms and producing a foam sheet having the foam.

[0008] In another embodiment, or in combination with any other embodiment described herein, there is provided a method for packaging a particulate material, the method comprising: (a) providing an expandable particulate composition comprising a cellulose ester and a plasticizer, the expandable particulate composition having a moisture content of 3000 ppm or less; and (b) introducing the particulate composition into a moisture-proof package to contain the composition therein. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a biodegradable article molding process according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram illustrating another biodegradable article molding process according to an embodiment of the present invention. [Figure 3] 3 is a schematic diagram illustrating an extrusion section that can be used in the article forming process of FIG. 1 and / or FIG. 2 according to an embodiment of the present invention. [Figure 4] 3 is a schematic diagram illustrating another extrusion section that can be used in the article forming process of FIGS. 1 and 2, according to an embodiment of the present invention. FIG. [Figure 5] 3 is a schematic diagram illustrating a sheet forming section that can be used in the article forming process of FIG. 1 and / or FIG. 2 according to an embodiment of the present invention. [Figure 6] 1 is a schematic diagram of a volatile material recovery system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments are generally directed to methods, systems, and compositions for forming biodegradable particulate materials (e.g., pellets), foam sheets, and articles. Exemplary processes, including methods, systems, and compositions, are shown in Figures 1-5 and are described in further detail below.

[0011] Methods and systems As shown in Figures 1 and 2, raw materials are introduced into a biodegradable polymer manufacturing 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 an embodiment, 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 acetic acid, to form a biodegradable cellulose ester polymer, such as a cellulose acetate polymer.

[0012] The biodegradable polymer material can then be introduced into a compounding process, in which the biodegradable polymer material is mixed with a plasticizer and, optionally, one or more other additives (e.g., stabilizers) to form a compounded material comprising a plasticized biodegradable polymer. Other additives can also be mixed with the polymer and plasticizer. For example, as shown in FIG. 2, the other materials (additives) can include, but are not limited to, stabilizers, physical blowing agent(s), chemical blowing agent(s) (and / or precursors), nucleating agent(s), surface-modifying additive(s), pigment(s), filler(s), and / or other additive(s). Mixing can be achieved by any known mixing technique, including, but not limited to, rolling in a cylindrical vessel, overhead stirring, sigma blade mixing, and tumbling.

[0013] The compounding process may include a granulation process. The granulation process may generally include mixing a biodegradable polymer material, a plasticizer, and other additive(s) to form a mixed composition and forming a particulate material from the composition. Specifically, the granulation process may include a pelletization process, and the particulate material may include multiple pellets. The term "compounded CE material" refers to the cellulose ester material formed during the compounding process, which may include a mixture of cellulose ester, a plasticizer, and other additives. Furthermore, such compounded CE material may be in the form of a particulate material or pellets. As used herein, it should be understood that the phrase "granulating" or "granulation process" can be the same as or at least include "pelletizing" or "pelletization process." In some embodiments, the granulation process may include pelletizing in a water bath, pelletizing on an air-cooled belt, pelletizing underwater, solvent blending, etc.

[0014] In one embodiment, or in combination with any other embodiment described herein, the plasticizer and other additive(s) can be mixed with the cellulose ester by conventional melt compounding techniques. This involves mixing the cellulose ester with the plasticizer and, optionally, other additives in a twin-screw extruder equipped with appropriate mixing elements at appropriate temperatures and pressures to obtain a molten, homogeneously combined cellulose ester mixture by the time the material exits the extruder. The molten, blended cellulose ester mixture may then be extruded through a die having an orifice with a diameter of approximately 2 to 6 mm to extrude strands. The strands can then be cooled with water (e.g., via underwater pelletization) or air and cut at regular intervals to obtain a uniform, desired size and shape, referred to as "pellets" or "granules." While a process for forming pelletized blended material is described herein, it will be understood that the blended material fed to the foam sheet manufacturing process can be in any physical form (e.g., pellets, powder, granules, fibers) according to some embodiments. The term "compounded CE material" refers to a cellulose ester material formed during a compounding process, which may include a mixture of cellulose esters, plasticizers, and other additives. Furthermore, such compounded CE materials may take the form of a molten mixture or particulate material (e.g., pellets, powders, granules, fibers, etc.).

[0015] The particulate CE material produced in the compounding process may typically have a moisture content (i.e., water content) of about 3000 ppm to about 10,000 ppm, depending on environmental and processing conditions. However, in some applications, such high levels of moisture content may result in unacceptably large cell sizes in the resulting foam, potentially resulting in poor foam quality. Therefore, in one embodiment, or in combination with any other embodiment mentioned herein, at least a portion of the particulate CE material produced in the compounding process may be dried by introducing the material into a drying system to reduce the moisture content, thereby providing a dried particulate material.

[0016] In one embodiment, or in combination with any other embodiment mentioned herein, the particulate CE material may be contacted with a forced steam (e.g., air) stream passing through a drying system. For example, compressed dry air may be used at a temperature and humidity sufficient to draw water from the composition. The drying temperature (i.e., the temperature of the steam stream) may be at least 60°C below the Tg of the CE material. Thus, the forced steam stream may have a temperature of 40°C to 80°C, or 50°C to 70°C. In some embodiments, the forced steam stream may be cooled and contacted with a desiccant material. Cooling the gas stream before contacting the desiccant material can advantageously condense certain volatile substances (for collection and / or reuse), allowing the desiccant to operate more efficiently. Additionally or alternatively, other drying methods may also be used, which may include one or more heating steps, air drying, and / or cyclone drying processes.

[0017] In one embodiment, or in combination with any other embodiment mentioned herein, the forced steam stream used in the drying system can be treated to remove (and optionally collect) entrained volatile and / or particulate matter (e.g., dust, fine particles, etc.), thereby allowing the treated steam stream to be recycled for use in the drying system. An exemplary system for treating a steam stream is shown in FIG. 6. The steam stream is supplied through an inlet, where it can optionally first be subjected to particulate filtration to remove dust and other particulate matter. The steam stream at the inlet can have a temperature of 40°C to 80°C, or 50°C to 70°C. The (optionally filtered) steam stream is then cooled and at least partially condensed. For example, the steam stream can be passed over a cooling coil or other heat exchanger, thereby condensing at least a portion of the volatile components of the steam stream. The steam stream and any condensed liquid can then be sent to a condensate collection zone, which can include one or more steps operable to remove condensate from the steam stream. For example, a first step may involve contacting the vapor stream with a baffle or other surface, on which condensate may form and flow downward into a catch basin located at the bottom of the treatment system. Other steps may involve redirecting (e.g., upward) and changing the velocity of the vapor stream, causing at least a portion of the entrained condensate to separate from the vapor stream and fall into the catch basin for collection and recovery. Additionally or alternatively, a second cooling step may 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 may condense 50-80% of the volatile components in the vapor stream, while the second cooling step may condense 20-50% of the volatile components in the vapor stream. Finally, the vapor stream may optionally be subjected to further filtration, including particulate filtration and / or scrubbing filtration, to recover any condensate remaining in the vapor stream before directing the vapor stream through an outlet. The temperature of the vapor stream exiting the system may be 0°C to 10°C lower, or 1°C to 5°C lower than the temperature of the vapor stream at the inlet.In some embodiments, the recovered condensate can be optionally filtered and stored or recycled for further use. For example, in some embodiments, the condensate includes blowing agents and / or plasticizers that were volatilized during drying, and the condensed blowing agents and / or plasticizers can be recycled for use in the compounding process described above.

[0018] In one embodiment, or in combination with any other embodiment mentioned herein, the moisture content of the dried CE particulate material is at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% less than the moisture content of the particulate CE material introduced into the drying system. In some embodiments, the moisture content of the dried CE particulate material is 3000 ppm or less, 2500 ppm or less, 2000 ppm or less, 1500 ppm or less, 1000 ppm or less, 900 ppm or less, 800 ppm or less, 700 ppm or less, or 600 ppm or less. In some embodiments, the moisture content of the dried particulate material is 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. The moisture content levels disclosed herein may be measured by one or both of Karl Fischer titration and / or the use of a moisture measuring device (e.g., aboni HydroTracer) to determine absolute moisture content.

[0019] 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 shipping and processing at a separate facility. The compounded CE material may be packaged with or without undergoing the drying process described above. For example, a freshly compounded CE material may have a sufficiently low moisture content that it can be packaged immediately before absorbing moisture from the environment. Alternatively, the compounded CE material may be dried to a desired moisture content as described above and then packaged. In either case, the moisture content of the packaged compounded CE material may be 3000 ppm or less, 2500 ppm or less, 2000 ppm or less, 1500 ppm or less, 1000 ppm or less, 900 ppm or less, 800 ppm or less, 700 ppm or less, or 600 ppm or less. In some embodiments, the compounded CE material may be packaged by introducing the material into a foil-lined (aluminized) bag and sealing it therein.

[0020] The dry-blended CE material, which may include pellets of plasticized biodegradable polymer as described above, can then be introduced into a foam sheet manufacturing process, as shown in Figures 1 and 2. The foam sheet manufacturing process can occur in the same facility as the compounding process, or the CE material can be shipped to a separate facility, unpackaged, and further processed in the foam sheet manufacturing process. The foam sheet manufacturing process can include one or more zones / steps for producing a foam sheet or film, which are described in more detail below. While an exemplary foam sheet manufacturing process is described herein, it should be understood that certain aspects described herein may also be applicable to rigid (i.e., non-foamed) materials and articles. As shown in Figure 1, 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 manufacturing process. Additives may include, but are not limited to, stabilizers, physical blowing agent(s), chemical blowing agent(s) (and / or precursors), nucleating agent(s), surface modification additive(s), pigment(s), filler(s), and / or other additive(s).

[0021] A foam sheet manufacturing process may generally include an extrusion section and a sheet forming section. An exemplary extrusion section is shown in FIG. 3. As shown, the extrusion section may include a feed preparation zone, where solid additives may be combined with the blended CE material and introduced into the downstream extrusion zone. In one embodiment, or in combination with any other embodiment mentioned herein, the feed preparation zone may include a feed hopper. Thus, the blended CE material and other solid additives may be deposited in the feed hopper, which directs the combined feed composition toward the extrusion zone. The feed preparation zone may further include a mixer, where the blended CE material and one or more additive(s) may be mixed before being introduced into the hopper. Mixing may be achieved by any known mixing technique, including, but not limited to, rolling in a cylindrical vessel, overhead stirring, sigma blade mixing, and tumbling. Exemplary solid additive(s) that can be combined with the compounding material can include chemical blowing agent(s), nucleating agent(s), surface modification additive(s), pigment(s), filler(s), and / or other additive(s).

[0022] The combined feed composition from the feed preparation zone can then be introduced into the extrusion zone. The extrusion zone generally can include one or more extruders, which can include a single-screw extruder and / or a twin-screw extruder. Within the extruder(s), the feed composition can be introduced into the extruder barrel and conveyed by the screw(s) through a die that forms an extrudate from the feed composition. The composition can be heated and at least partially melted as it is conveyed through the extruder barrel toward the die. Thus, the term "CE melt composition" is used herein to refer to a cellulose ester-based feed composition that has been melted into a flowable molten resin through the extrusion section. Heat can be provided by an external heater disposed along the outside of the extruder barrel. The shape of the extrudate generally depends on the shape and size of the die head. The extrudate can be further shaped by downstream processes, as described below.

[0023] One or more additive(s) can be introduced into the CE melt composition while it is in the extruder. For example, one or more physical blowing agent(s) can be added to the CE melt composition by injecting the physical blowing agent into the composition as it is conveyed in the extruder barrel.

[0024] As shown in FIG. 4 , 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 can be combined into an integrated unit. In either case, the feed composition from the feed preparation zone is introduced into the primary extrusion vessel and at least partially melts as it is conveyed through the extruder barrel as described above, thereby producing a CE melt composition. The CE melt composition exiting the primary extrusion vessel can have a temperature of about 220° C. to about 240° C. One or more additives, such as blowing agent(s), can be added to the CE melt composition as it is conveyed through the primary extrusion vessel.

[0025] The CE melt composition from the primary extrusion vessel is then introduced into a cooling vessel. The cooling vessel may be a secondary extrusion vessel, which operates similarly to the primary extrusion vessel but at a lower temperature. Within the cooling vessel, the CE melt composition can be further mixed to provide a substantially homogeneous mixture of the molten polymer and other additive(s). The CE melt composition can then be passed through a die and exited through a die head to provide a cellulose ester-based extrudate, which can be further processed in the sheet forming section of the foam sheet manufacturing 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.

[0026] As shown in Figure 4, one or more filtration devices may be installed within the extrusion section to filter out particulate matter from the CE melt composition. For example, a screen changer filtration device may be installed downstream of the primary and secondary extrusion vessels to remove solid components from the CE melt composition before it passes through the die head and onto the sheet forming section.

[0027] The sheet forming section can include any of a variety of systems and processes for shaping the cellulose ester material extrudate into a sheet that can be used to form an article. The shape of the extrudate is generally determined by the shape of the die head, while the shape of the sheet formed in the sheet forming section can be determined by the shape of the die head and other downstream processes. For example, the extrudate can have a generally flat shape or can be annular and undergo further processing to form a flat sheet. In embodiments where the die has a circular 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. Furthermore, the thickness of the opening through which the extrudate exits, 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.

[0028] An exemplary sheet forming section is shown in Figure 5. As shown, the CE melt composition is extruded through an annular die and drawn over a forming mandrel. A cooling fluid (e.g., air) can be flowed inside and / or outside the extrudate to cool the extrudate material as it passes over the mandrel. For example, a cooling fluid can be blown from the mandrel toward the die to cool the inner surface of the extrudate between the die and the mandrel. Additionally or alternatively, a cooling fluid can be flowed over the mandrel to cool the outer surface of the extrudate as it passes over the mandrel.

[0029] A slicer (or cutting device) can be used to open the tubular extrudate, allowing the tubular shape to be formed into a flat sheet. For example, the tubular extrudate passing over a mandrel can be slit open and pulled to a tensioning station containing one or more rollers. The rollers flatten the extrudate and maintain the amount of tension in the extrudate necessary to continue pulling the extrudate over the mandrel. The flattened extrudate, generally in the form of a sheet, may then be directed to a winding station where the material may be wound for packaging and shipping.

[0030] Referring again to Figures 1 and 2, the sheet produced by the sheet-making process can be used to form foamed articles, which are 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.).

[0031] composition The above-described process may include the preparation and extrusion of a composition that can be used in downstream processing to form a useful article. For example, in one embodiment, or in combination with any other embodiment mentioned herein, the extrusion feed material may include a particulate material including a biodegradable polymer, a plasticizer, and optionally one or more additive(s), such as those described herein. In one embodiment, or in combination with any other embodiment mentioned herein, the feed material may be combined with one or more additive(s), such as those described herein, to provide a blended composition including a biodegradable polymer, a plasticizer, and one or more additive(s). In one embodiment, or in combination with any other embodiment mentioned herein, the biodegradable polymer includes a cellulose ester. Further details of the composition components, including a biodegradable polymer (e.g., a cellulose ester), a plasticizer, and other additives, are provided below.

[0032] Cellulose ester The cellulose esters utilized as described herein can be any known in the art. Cellulose esters that can be used in embodiments herein generally include repeating units of the following structure:

[0033] [ka]

[0034] In the formula, R 1 , R 2 , and R 3 are independently selected from the group consisting of hydrogen, acetyl, propyl, or butyl. The substitution level of a cellulose ester is usually expressed in terms of degree of substitution ("DS"), which is the average number of non-OH substituents per anhydroglucose unit ("AGU"). Conventional cellulose generally contains three hydroxyl groups per substitutable AGU unit. Therefore, DS can have a value between 0 and 3. Natural cellulose is a large polysaccharide with a degree of polymerization of 250 to 5,000, even after pulping and purification, so the assumption that the maximum DS is 3.0 is generally correct. Because DS is a statistical average, a value of 1 does not guarantee that every AGU has a single substituent. In some cases, unsubstituted anhydroglucose may exist, some with two or some with three substituents, and the value will usually be a non-integer. Total DS is defined as the average number of all substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to specific substituents, such as hydroxyl or acetyl. In one embodiment, or in combination with any other embodiment, n is an integer ranging from 25 to 250, or from 25 to 200, or from 25 to 150, or from 25 to 100, or from 25 to 75.

[0035] In one embodiment, or in combination with any other embodiment, the cellulose ester has at least two anhydroglucose rings and may have at least 50 to a maximum of 5,000 anhydroglucose rings, or at least 50 to less than 150 anhydroglucose rings. The number of anhydroglucose units per molecule is defined as the degree of polymerization (DP) of the cellulose ester. In one embodiment, or in combination with any other embodiment, the cellulose ester may have an intrinsic viscosity (IV) of about 0.2 to about 3.0 deciliters / gram, or about 0.5 to about 1.8, or about 1 to about 1.5, measured at 25°C on a 0.25 gram sample in 100 ml of a 60 / 40 weight percent solution of phenol / tetrachloroethane. In one embodiment, or in combination with any other embodiment, the cellulose ester useful herein may 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 substituted ester is acetyl.

[0036] Cellulose ester can be produced by any method known in the art.The example of the production process of cellulose ester is taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th Edition, Vol.5, Wiley-Interscience, New York (2004), pp.394-444.The cellulose that is the starting material for producing cellulose ester can be obtained from various grades and sources, such as cotton linters, softwood pulp, hardwood pulp, corn fiber and other agricultural sources, and bacterial cellulose, among others.

[0037] One method for producing cellulose esters involves esterifying cellulose by mixing it with an appropriate organic acid, an acid anhydride, and a catalyst. The cellulose is then converted into a cellulose triester. A water-acid mixture is then added to the cellulose triester to carry out ester hydrolysis, which can then be filtered to remove gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester can then be washed with water to remove reaction by-products, followed by dehydration and drying.

[0038] The cellulose triester that is hydrolyzed can have three acetyl substituents.These cellulose esters can be prepared by a number of methods known to those skilled in the art.For example, cellulose esters can be prepared by the heterogeneous acylation of cellulose in a mixture of carboxylic acid and anhydride in the presence of a catalyst such as H2SO4.Cellulose triester can also be prepared by the homogeneous acylation of cellulose dissolved in a suitable solvent such as LiCl / DMAc or LiCl / NMP.

[0039] Those skilled in the art will understand that the trade term cellulose triester also includes cellulose esters that are not fully acyl-substituted. For example, cellulose triacetate commercially available from Eastman Chemical Company, Kingsport, TN, USA, typically has a DS of about 2.85 to about 2.99.

[0040] After esterification of cellulose to triester, some of the acyl substituents can be removed by hydrolysis or alcoholysis to obtain secondary cellulose ester.As mentioned above, depending on the specific method used, the distribution of acyl substituents can be random or non-random.Also, secondary cellulose ester can be prepared directly without hydrolysis by using a limited amount of acylating reagent.This process is particularly useful when the reaction is carried out in a solvent that dissolves cellulose.All of these methods produce cellulose esters that are useful in the present invention.

[0041] In one embodiment, or in combination with any of the mentioned embodiments, the cellulose acetate is a cellulose diacetate having a polystyrene-equivalent number average molecular weight (Mn) of about 10,000 to about 100,000, as measured by gel permeation chromatography (GPC) using polystyrene-equivalent Mn according to ASTM D6474 using NMP as the solvent. In one embodiment, or in combination with any other embodiment, the cellulose acetate composition has a NA of 10,000 to 90,000, or 10,000 to 80,000, or 10,000 to 70,000, or 10,000 to 60,000, or less than 10,000 to 60,000, or 10,000 to 55,000, or 10,000 to 50,000, or less than 10,000 to 50,000, or 10,000 to 45,000, or 10,000 to 40,000, or 10,000 to 30,000, or 20,000, as measured by gel permeation chromatography (GPC) according to ASTM D6474 using NMP as a solvent. 00 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 60,000 The cellulose diacetate has a polystyrene-equivalent number average molecular weight (Mn) of less than 0.00, 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.

[0042] The most common commercially available secondary cellulose esters are produced by first heterogeneously acylating cellulose with an acid catalyst to form a cellulose triester. After obtaining a homogeneous solution of the cellulose triester in the corresponding carboxylic acid, the cellulose triester is then subjected to hydrolysis until the desired degree of substitution is achieved. After isolation, random secondary cellulose esters are obtained, i.e., the relative degree of substitution (RDS) at each hydroxyl is approximately equal.

[0043] The cellulose esters useful in the present invention can be prepared using techniques known in the art and can be selected from a variety of cellulose esters, such as those available from Eastman Chemical Company, Kingsport, TN, USA, such as Eastman™ Cellulose Acetate CA398-30 and Eastman™ Cellulose Acetate CA398-10, Eastman™ CAP485-20 Cellulose Acetate Propionate, and Eastman™ CAB381-2 Cellulose Acetate Butyrate.

[0044] In one embodiment, or in combination with any other embodiment, the cellulose ester can be prepared by converting cellulose to a cellulose ester using reactants obtained from recycled materials, such as recycled plastic-containing syngas sources. In one embodiment, or in combination with any other embodiment, such reactants can be cellulose reactants including organic acids and / or acid anhydrides used in esterification or acylation reactions of cellulose, such as those discussed herein.

[0045] In one embodiment of the present invention, or in combination with any of the mentioned embodiments, or in combination with any of the mentioned embodiments, there is provided a cellulose ester composition comprising at least one regenerated cellulose ester, wherein the cellulose ester has at least one substituent on an anhydroglucose unit (AU) derived from a recycled-containing material (e.g., recycled plastic-containing syngas).

[0046] In one embodiment, or in combination with any other embodiment, the cellulose ester composition comprises 50-99 wt%, or 60-99 wt%, or 70-99 wt%, or 80-99 wt%, or 50-98 wt%, or 60-98 wt%, or 70-98 wt%, or 80-98 wt%, or 90-98 wt%, or 50-90 wt%, or 60-90 wt%, or 70-90 wt%, or 80-90 wt%, or 90-99 wt%, or 50-80 wt%, or 60-80 wt%, or 70-80 wt%, or 50-70 wt%, or 60-70 wt%, or 50-60 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein may comprise a combination, blend, or mixture of two or more different types of cellulose esters. For example, in some embodiments, the cellulose esters used herein may be composed of a blend of two or more cellulose esters having different DSAc, where the blend may have a total DSAc of 2.2 to 2.8, or 2.0 to 2.9.

[0047] plasticizer In one embodiment, or in combination with any other embodiment, the cellulose ester compositions described herein can include at least one plasticizer, which lowers the melting temperature, or Tg, and / or melt viscosity of the cellulose ester. Plasticizers for cellulose esters include glycerol triacetate (triacetin), glycerol diacetate (diacetin), dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, polyethylene glycol (molecular weight 200-600), dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl o-benzoylbenzoate, triethylene glycol dipropionate, 1,2-epoxypropyl phenylethylene glycol, 1,2-epoxypropyl (m-cresyl) ethylene glycol, 1,2-epoxypropyl (o-cresyl) ethylene glycol, β-oxyethyl cyclohexene carboxylate, bis(cyclohexanate) diethylene glycol, triethyl citrate, polyethylene glycol, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetylated tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, poly Ethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and glycol tribenzoate, benzoate-containing plasticizers such as the Benzoflex™ plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, o-cresyl paratoluenesulfonate, n-ethyltoluenesulfonamide, adipate-based plasticizers, soybean oil epoxides such as the Paraplex™ plasticizer series, sucrose-based plasticizers, di Possible additives include butyl sebacate, tributyrin, sucrose acetate isobutyrate, Resolflex™ series plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (ethyl phthalyl ethyl glycolate "EPEG" and methyl phthalyl ethyl glycolate "MPEG"), methoxypolyethylene glycol, 2,2,4-trimethylpentane-1,3-diylbis(2-methylpropanoate), and polycaprolactone.In some embodiments, the plasticizers used herein may include a combination or mixture of two or more different types of plasticizers.

[0048] In one embodiment, or in combination with any other embodiment mentioned herein, 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.

[0049] In one embodiment, or in combination with any other embodiment, the plasticizer is a food-compatible plasticizer. Food-compatible means compliant with applicable food additive and / or food contact regulations, i.e., the plasticizer is permitted for use or recognized as safe by at least one (national or regional) food safety regulatory agency (or organization), e.g., listed in the 21 CFR Food Additive Regulations, or otherwise recognized by the U.S. FDA as Grass Acceptable (GRAS). In one embodiment, or in combination with any other embodiment, the food-compatible plasticizer is triacetin or polyethylene glycol (PEG) having a molecular weight of about 200 to about 600. Examples of food-compatible plasticizers that may be considered in one embodiment, or in combination with any other embodiment, may include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and glycol tribenzoate.

[0050] In one embodiment, or in combination with any other embodiment, the plasticizer can be present in an amount sufficient to enable the cellulose ester composition to be melt processed (or thermoformed) in conventional melt processing equipment into useful articles, such as disposable plastic items. In one embodiment, or in combination with any other embodiment, the plasticizer is present in an amount of 1 to 40 wt %, alternatively 5 to 25 wt %, or 10 to 25 wt %, or 12 to 20 wt %, for most thermoplastic processing, based on the weight of the cellulose ester composition. In one embodiment, or in combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be achieved with plasticizer levels ranging from 10 to 30, or 12 to 25, or 15 to 20, or 10 to 25 wt %, based on the weight of the cellulose ester composition.

[0051] In one embodiment, or in combination with any other embodiment, the plasticizer is a biodegradable plasticizer. Some examples of biodegradable plasticizers include triacetin, triethyl citrate, acetyltriethyl citrate, polyethylene glycol, benzoic acid-containing plasticizers such as the Benzoflex™ plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, adipic acid-based plasticizers, soybean oil epoxides such as the Paraplex™ plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributyrin, Resolflex™ series plasticizers, triphenyl phosphate, glycolic acid, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diylbis(2-methylpropanoate), and polycaprolactone.

[0052] In one embodiment, or in combination with any other embodiment, the cellulose ester composition may contain a plasticizer selected from the group consisting of PEG and MPEG (methoxy PEG). The polyethylene glycol or methoxy polyethylene glycol composition has an average molecular weight of 200 Daltons to 600 Daltons, and the composition is melt-processible, biodegradable, and disintegrable.

[0053] In one embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol or methoxy PEG having an average molecular weight of 300 to 550 daltons.

[0054] In one embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol having an average molecular weight of 300 to 500 daltons.

[0055] In one embodiment, or in combination with any other embodiment, the cellulose ester composition comprises at least one plasticizer (as described herein) in an amount of 1 to 40 wt%, or 5 to 40 wt%, or 10 to 40 wt%, or 12 to 40 wt%, or 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%, all based on the total weight of the cellulose ester composition. , or 13 to 30% by weight, or 15 to 30% by weight, or greater than 15 to 30% by weight, or 17 to 30% by weight, or 5 to 25% by weight, or 10 to 25% by weight, or 13 to 25% by weight, or 15 to 25% by weight, or greater than 15 to 25% by weight, or 17 to 25% by weight, or 5 to 20% by weight, or 10 to 20% by weight, or 13 to 20% by weight, or 15 to 20% by weight, or greater than 15 to 20% by weight, or 17 to 20% by weight, or 5 to 17% by weight, or 10 to 17% by weight, or 13 to 17% by weight, or 15 to 17% by weight, or greater than 15 to 17% by weight, or less than 5 to 17% by weight, or less than 10 to 17% by weight, or less than 13 to 17% by weight, or less than 15 to 17% by weight.

[0056] In one embodiment, or in combination with any other embodiment, the at least one plasticizer includes or is a food-compatible or FDA-approved plasticizer, such as triacetin or PEG (MW 300-500).

[0057] biodegradable polymers In one embodiment, or in combination with any other embodiment, the cellulose ester composition described herein comprises a BCE component comprising at least one biodegradable cellulose ester (BCE), which may include one or more of the cellulose esters described herein, and a biodegradable polymer component comprising at least one other biodegradable polymer (other than BCE). In one embodiment, or in combination with any other embodiment, the other biodegradable polymer may be selected from polyhydroxyalkanoates (PHAs and PHBs), 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 a biodegradable polymer (other than BCE) in an amount of 0.1 to less than 50 wt%, or 1 to 40 wt%, or 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, based on the cellulose ester composition. In one embodiment, or in combination with any other embodiment, the cellulose ester composition contains a biodegradable polymer (other than BCE) in an amount of 0.1 to less than 50 wt%, or 1 to 40 wt%, or 1 to 30 wt%, or 1 to 25 wt%, or 1 to 20 wt%, based on the total amount of BCE and biodegradable polymer.In one embodiment, or in combination with any other embodiment, the at least one biodegradable polymer has a weight average molecular weight (Mw) of 10,000 to 1,000,000, or 50,000 to 1,000,000, or 100,000 to 1,000,000, or 2,000 to 3,000,000, as measured by gel permeation chromatography (GPC) using a refractive index detector and polystyrene standards in methylene chloride. In one embodiment, or in combination with any other embodiment, the PHA may include a PHA in the range of 50,000 to 1,000,000, or 500,000 to 1,000,000, or 600,000 to 1,000,000, or 600,000 to 900,000, or 700,000 to 800,000, or 10,000 to 500,000, or 10,000 to 250,000, or 10,000 to 100,000, or 10,000 to 50,000. In one embodiment, or in combination with any other embodiment, the PHA may include polyhydroxybutyrate-co-hydroxyhexanoate.

[0058] nucleating agent Nucleating agents refer to chemical or physical materials that provide sites for cell formation in a molten blend mixture, such as in a CE melt composition. As described in more detail below, nucleating agents can be added to blended CE materials during the blending process. Alternatively, or in addition, nucleating agents may be added during the foam sheet manufacturing process. For example, nucleating agents can be blended with blends introduced into the hopper of an extruder in the extrusion section. Alternatively, nucleating agents can be added to the CE melt composition in the extruder itself. Nucleating agents can include physical nucleating agents and chemical nucleating agents. Physical nucleating agents are substances that are immiscible with the polymer matrix of the CE melt composition at the extrusion temperature in the extrusion section. Chemical nucleating agents are substances that react (e.g., decompose) during extrusion (e.g., at the extrusion temperature in an extruder) to form a physical nucleating agent. Thus, chemical nucleating agents can be considered (and referred to herein as) precursors to in situ formed physical nucleating agents.

[0059] Suitable physical nucleating agents include particulates having a desired particle size and / or shape to create cell nucleation sites within the CE melt composition. For example, in some embodiments, the physical nucleating agent has an average particle size of less than 1000 microns, less than 500 microns, less than 100 microns, less than 50 microns, less than 25 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 2 microns, less than 1.5 microns, and / or less than 1.0 micron. However, in some other embodiments, it may be preferable to have nanoscale-sized particles. Furthermore, in some embodiments, the physical nucleating agent preferably has a high aspect ratio (i.e., width:height). For example, in some embodiments, the physical nucleating agent has an average aspect ratio of greater than 1:1, greater than 2:1, greater than 5:1, greater than 10:1, greater than 20:1, greater than 30:1, greater than 40:1, greater than 50:1, greater than 75:1, and / or greater than 100:1. Additionally, as noted above, the physical nucleating agent must be immiscible with the polymer matrix of the CE melt 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 may also be selected to have the ability to recrystallize upon cooling after melting.

[0060] Examples of suitable inorganic physical nucleating agents include, but are not limited to, minerals such as talc, CaCO3, mica, and mixtures of at least two of the foregoing. One representative example is Heritage Plastics HT6000 Linear Low Density Polyethylene (LLDPE) Based Talc Concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon oxide, titanium oxide, magnesium oxide, aluminum oxide and calcium silicate, barium sulfate, kaolin, aluminum trihydrate ATH (Al(OH)3), MDH (Mg(OH)2), diatomaceous earth, magnetite / hematite, halloysite, zinc oxide, and titanium dioxide. In some embodiments, the inorganic nucleating agent comprises an oxide, such as a metal oxide or mixed metal oxide, such as one selected from one or more of the following: aluminum oxide, antimony oxide, arsenic oxide, bismuth oxide, boron oxide, calcium oxide, gallium oxide, iron oxide, lithium oxide, magnesium oxide, silicon oxide, and titanium oxide. In other embodiments, the inorganic nucleating agent comprises a silicate, such as a silicate selected from one or more of the following: magnesium silicate and calcium silicate.

[0061] It has been found that biodegradable natural particulate materials (e.g., organic nucleating agents) derived from renewable organic sources can also function as effective physical nucleating agents. Natural materials that can serve as physical nucleating agents include materials composed of cellulose fiber and / or cellulose starch. Examples include, but are not limited to, almond shell flour, animal fiber, apricot shell flour, bamboo flour, bark flour, seashell flour, coconut shell flour, coconut fiber, cork flour, corncob flour, corncob grit, cottonseed husks, flock and fiber, hazelnut shell flour, kenaf flour, natural fiber, nut shell husks and flour, oat fiber powder, olive stone flour, peanut husk flour, pecan shell flour, pine nut shell powder, pistachio nut shell flour, vegetable fiber, rice husk flour, rice husk grit, rice husk, soybean flour, starch powder (hydrophobic), walnut shell flour, wheat chaff, wheat husk, and wood flour. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, metallic stearates, carbon black, and dolomite.

[0062] As noted above, suitable chemical nucleating agents (or in situ formed precursors to physical nucleating agents) are configured to decompose upon reaching a threshold chemical reaction temperature to generate cell nucleation sites in the CE melt composition. These small cells serve as nucleation sites for the growth of larger cells from physical or other types of blowing agents. In some embodiments, the precursor is configured to form a gas, such as CO or N, during extrusion of the particulate material.

[0063] Examples of chemical nucleating agents include, but are not limited to, acids such as citric acid or citric acid-based materials. Other acids may include lauric acid, stearic acid, tartaric acid, ascorbic acid, propionic acid, and hexanoic acid. One representative example is HYDROCEROL™ CF-40E (available from Clariant Corporation), which contains citric acid and a nucleating agent. In some embodiments, the chemical nucleating agent includes a combination of an acid and a base, such as a carbonate, including sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate. 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 may include a carrier in which the active ingredient of the nucleating agent is 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 may include polystyrene. However, the carrier may comprise other compositions, such as various biopolymers (e.g., polybutylene succinate, Capa polyester, etc.), polyolefins, acrylic copolymers (e.g., ethylene methyl acrylate), etc. In some such embodiments, citric acid and sodium bicarbonate may comprise approximately half of the chemical nucleating agent (by weight), while the carrier comprises the other half (by weight). Furthermore, in some such embodiments, there may be more sodium bicarbonate than citric acid in the chemical nucleating agent. For example, there may be approximately three times as much sodium bicarbonate as citric acid in the chemical nucleating agent (by weight). It should also be understood that in some embodiments, such as when the nucleating agent is Hecofoam or Hydrocerol, a carrier may not be required or used.

[0064] In one embodiment, or in combination with any of the embodiments described herein, the nucleating agent is present in an amount of 0.1 to 10 wt%, 0.1 to 5.0 wt%, at least 0.1 wt%, at least 0.25 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.25 wt%, at least 1.5 wt%, at least 1.75 wt%, at least 2.0 wt%, at least 2.25 wt%, at least 2.5 wt%, at least 2.75 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt%, and / or less than 7.5 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agent used herein may comprise a combination or mixture of two or more different types of nucleating agents. 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% talc.

[0065] It should be noted that cellulose ester materials, whether in the form of a compounded CE material or a CE melt composition, generally can tolerate a maximum amount of nucleating agent capable of functioning to form nucleation sites. Any remaining nucleating agent added to the cellulose ester material remains as filler. Depending on the type of filler used, fillers can provide various properties to the resulting cellulose ester foam and / or article. For example, some fillers can increase / decrease the density, ductility, Young's modulus, yield strength, heat deflection temperature, permeability, impact resistance, elongation to break, adhesive properties, biodegradation, etc. of the cellulose ester material. Fillers can also be used to change the visual (e.g., color, opacity, etc.) and tactile (e.g., material continuity, surface roughness, etc.) properties of the cellulose ester material.

[0066] foaming agent A blowing agent refers to a physical or chemical material (or combination of materials) that acts to expand nucleation sites. Blowing agents can include chemical blowing agents, physical blowing agents, a combination thereof, or several types of chemical and physical blowing agents. Blowing agents function to reduce the density of the material by expanding cells formed in the molten compound at the nucleation sites. Blowing agents may be added to the CE melt composition in the extruder. It has surprisingly been discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture and carry the absorbed water into the molten composition mixture, where the water can act as a physical blowing agent.

[0067] Examples of physical blowing agents include H2O, N2, CO2, alkanes, alkenes, ethers, ketones, argon, helium, air, or mixtures. Furthermore, it has surprisingly been discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture and carry the absorbed water into the molten resin mixture, where the water can act as a physical blowing agent. The hygroscopic, biodegradable natural fillers can be incorporated into the composition and allowed to absorb moisture prior to the foaming process, after which the water is released and acts as a physical blowing agent. Beneficially, water can also be used as a plasticizer for cellulose ester resins. Furthermore, in some embodiments, physical blowing agents can include hydrocarbons such as pentane / isopentane or butane / isobutane. Other hydrocarbons can include propane, ethane, methane, hexane, cyclohexane, cyclopentane, or cyclobutene.

[0068] Chemical blowing agents are materials that decompose or react to produce a gas (e.g., CO2 or N2). Such gas expands cells within the molten resin mixture and / or the resulting foam mixture, producing a structural material with multiple gas voids dispersed throughout. Chemical blowing agents can be endothermic or exothermic. Chemical blowing agents typically degrade and decompose at a specific temperature, releasing a gas. Examples of chemical blowing agents include azodicarbonamide, acids (e.g., citric acid), and carbonates (e.g., sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, etc.), and combinations thereof.

[0069] 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% by weight, or 1.3 to 3.0% by weight, or 1.3 to 3.5% by weight, or 1.3 to 4.0% by weight, or 1.3 to 4.5% by weight, or 1.3 to 5.0% by weight, or 1.3 to 5.5% by weight, or 1.5 to 3.0% by weight, or 1.5 to 4.0% by weight, or 1.5 to 5.0% by weight, or 1.5 to 6.0% by weight, or 2.0 to 3.0% by weight, or 2.0 to 4.0% by weight, or 2.0 to 5. 0.0% by weight, or 2.0 to 6.0% by weight, or 2.5 to 3.0% by weight, or 2.5 to 4.0% by weight, or 2.5 to 5.0% by weight, or 2.5 to 6.0% by weight, or 3.0 to 4.0% by weight, or 3.0 to 5.0% by weight, or 3.0 to 6.0% by weight, or 0.0 to 9.0% by weight, or 0.5 to 9.0% by weight, or 1.0 to 9.0% by weight, or 1.5 to 9.0% by weight, or 2.0 to 9.0% by weight , or 2.5-9.0 wt%, or 3.0-9.0 wt%, or 3.5-9.0 wt%, or 4.0-9.0 wt%, or 4.5-9.0 wt%, or 5.0-9.0 wt%, or 5.5-9.0 wt%, or 6.0-9.0 wt%, or 6.5-9.0 wt%, or 7.0-9.0 wt%, or 7.5-9.0 wt%, or 8.0-9.0 wt%, or 8.5-9.0 wt%. In some embodiments, the blowing agent used herein may comprise a combination or mixture of two or more different types of blowing agents.

[0070] Surface Modification Additives Surface-modifying additives refer to materials that can be added to cellulose ester compositions to modify the structure of the compositions (or the resulting foamed articles) in order to improve the processability of the cellulose ester compositions. For example, the inventors of the present application have discovered that adding a surface-modifying additive to compounded CE materials (e.g., pellets during the compounding process) or to CE melt compositions (e.g., during the extrusion process) can improve processing by reducing undesirable sticking of the CE melt composition to the die or mandrel (or other components of the foam sheet manufacturing process). This reduction in sticking can be achieved by the surface-modifying additive inhibiting the fusion of the cellulose ester caused by plasticizers. The addition of a surface-modifying additive can also reduce blocking in cellulose ester foam sheets produced in the sheet forming section. Furthermore, the surface-modifying additive can also improve the foam sheet manufacturing process by allowing the process to be carried out at lower temperatures.

[0071] Furthermore, in some embodiments, the surface modification additive may function as an antistatic additive to suppress electrical sparks or arcing in the CE melt composition. Suppression of electrical sparks or arcing may be particularly important when hydrocarbons are used as blowing agents to reduce the likelihood of the hydrocarbons igniting and causing a fire. Beneficially, the surface modification additive may also reduce the diffusion of blowing agents such as hydrocarbons from the foam sheet or resulting article. In some embodiments, the hydrocarbon itself may be used as the surface modification additive.

[0072] Nevertheless, more common examples of surface modification additives that can be used with compounded CE materials (e.g., during the compounding process) or to the CE melt composition (e.g., during the foam sheet manufacturing process) in accordance with embodiments of the present invention include fatty acids such as palmitic acid, tallow acid, stearic acid, oleic acid, linoleic and linolenic acids, arachidic / behenic acid, behenic acid, and erucic acid. Surface modification additives can also include fatty acid amides such as erucamide, oleamide, stearamide, benamide, secondary amides, and bisamides.

[0073] Additional examples of surface-modifying additives may include glycerol esters and / or stearic acid esters, such as monoglycerides, diglycerides, and triglycerides. Monoglycerides may include glycerol monostearate or monoglyceride derivatives, such as diacetyl tartaric acid esters of mono- and diglycerides (DATEM), ethoxylated monoglycerides, succinyl monoglycerides, and propylene glycol monoesters (PGME). Examples of surface-modifying additives may also include metal stearates, such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate, and / or combinations thereof (e.g., calcium stearate / zinc stearate). Examples of surface modification additives may also include waxes such as polyolefin waxes (polypropylene waxes and polyethylene waxes), oxidized olefin waxes, ethylene acrylic acid (EAA) copolymer waxes, ethylene methyl acrylate (EMA) copolymer waxes, EAA ionomer waxes, acrylic waxes, and / or natural waxes (such as rice bran wax, sunflower wax, sugarcane wax, candelilla wax, soy wax, beeswax, candelilla wax, and carnauba wax).

[0074] Other non-exclusive examples of surface modification additives include aliphatic diesters (e.g., dioctyl adipate), polyglycol diesters, alkyl alkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters, and alkyl monoesters. Additionally, various oils, such as aromatic oils, naphthenic oils, glyceride oils, silicone oils, and epoxidized oils (e.g., soybean oil and linseed oil), can be used as surface modification additives. Thus, in some embodiments, the surface modification additive includes a plasticizer, such as an aliphatic diester plasticizer or a polyester plasticizer. Furthermore, in some embodiments, the surface modification additive can include a polyhedral oligomeric silsesquioxane (POSS).

[0075] More generally, the surface modification additives used in embodiments of the present invention may be less polar than the cellulose ester in the compounded CE material (e.g., during the compounding process) or the CE melt composition (e.g., during the foam sheet manufacturing process). For example, the surface modification additive may have a solubility (based on Hansen solubility parameters) of 25 MPa 1 / 2 Less than 20MPa 1 / 2 Less than or 19.5MPa 1 / 2 Total solubility parameter δ less than 18 MPa 1 / 2 Less than 16MPa 1 / 2 Less than or 14MPa 1 / 2 Dispersion force solubility parameter δ less than d ;12MPa 1 / 2 Less than 8MPa 1 / 2 Less than or 4MPa 1 / 2 Dipolar intermolecular force solubility parameter δ less than d ; and / or 11 MPa 1 / 2 Less than 10MPa 1 / 2 Less than or 9MPa 1 / 2 Hydrogen bond solubility parameter δ less than hHowever, in some other embodiments, the surface modification additive used in embodiments of the present invention may be more polar than the cellulose ester in the compounded CE material (e.g., during the compounding process) or the CE melt composition (e.g., during the foam sheet manufacturing process). For example, the surface modification additive may have a solubility of 21.5 MPa (based on the Hansen solubility parameter). 1 / 2 Super, 23MPa 1 / 2 Over 25 MPa 1 / 2 The surface modification additive may have a total solubility parameter δ of greater than 100 g / mol, 150 g / mol, 220 g / mol, 260 g / mol, 300 g / mol, or 340 g / mol, and / or a molecular weight of 1000 g / mol or less, 2500 g / mol or less, or 5000 g / mol or less. Furthermore, it may be preferable for the surface modification additive to be insoluble in the plasticizer(s) used in the cellulose ester composition. For example, it may be preferable for the surface modification additive to be insoluble in triacetin. Finally, in some embodiments, the surface modification additive may be biodegradable and / or food-compatible or FDA-approved.

[0076] In one embodiment, or in combination with any of the embodiments described 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%, or 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 may include a combination or mixture of two or more different types of surface modification additives.

[0077] Goods Extruded sheets of cellulose ester foam can be formed using the extrusion section and / or sheet forming section described above. Such extruded sheets include a structural material having a plurality of gas voids disposed throughout. These gas voids are formed by the expansion of a blowing agent in the form of a gas within a cellulose polymer melt. The structural material is based on cellulose ester, and the specific amounts of the structural material's components (e.g., cellulose ester, plasticizer, nucleating agent, surface-modifying additive, etc.) are described in more detail above. Articles can be formed from 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.).

[0078] In one embodiment, or in combination with any of the embodiments mentioned herein, the foam has a density of 0.20 g / cm 3 Less than 0.18g / cm 3 Less than 0.15g / cm 3 Less than 0.12g / cm 3 Less than 0.10g / cm 3 Less than 0.08g / cm 3 Less than 0.06g / cm 3 Less than or equal to 0.04 g / cm 3 Less than or 0.04 to 0.8 g / cm 3 , 0.04~0.6g / cm 3 , 0.04~0.5g / cm 3 , 0.04~0.4g / cm 3 , 0.04~0.3g / cm 3 , 0.04~0.2g / cm 3 , 0.04~0.15g / cm 3 , 0.04~0.12g / cm 3 , 0.04~0.10g / cm 3 , 0.04~0.08g / cm 3 , 0.04~0.06g / cm 3, 0.06~0.8g / cm 3 , 0.06~0.6g / cm 3 , 0.06~0.5g / cm 3 , 0.06~0.4g / cm 3 , 0.06~0.3g / cm 3 , 0.06~0.2g / cm 3 , 0.06~0.15g / cm 3 , 0.06~0.12g / cm 3 , 0.06~0.10g / cm 3 , 0.06~0.08g / cm 3 , 0.08~0.8g / cm 3 , 0.08~0.6g / cm 3 , 0.08~0.5g / cm 3 , 0.08~0.4g / cm 3 , 0.08~0.3g / cm 3 , 0.08~0.2g / cm 3 , 0.08~0.15g / cm 3 , 0.08~0.12g / cm 3 , 0.08~0.10g / cm 3 , 0.1~0.8g / cm 3 , 0.1~0.6g / cm 3 , 0.1~0.5g / cm 3 , 0.1~0.4g / cm 3 , 0.1~0.3g / cm 3 , 0.1~0.2g / cm 3 , 0.1~0.15g / cm 3 , 0.1~0.12g / cm 3 , 0.2~0.8g / cm 3 , 0.2~0.6g / cm 3 , 0.2~0.5g / cm 3 , 0.2~0.4g / cm 3 , 0.2~0.3g / cm 3 , 0.3~0.6g / cm 3 , 0.3~0.5g / cm 3 , 0.3~0.4g / cm 3 , 0.4~0.6g / cm 3 , 0.4~0.5g / cm 3 , or 0.5 to 0.6 g / cm 3 It has a density of

[0079] In one embodiment, or in combination with any of the embodiments mentioned herein, the average foam cell size is 40 μm to 600 μm, or 50 μm to 600 μm, or 60 μm to 600 μm, or 70 μm to 600 μm, or 80 μm to 600 μm, or 90 μm to 600 μm, or 100 μm to 600 μm, or 150 μm to 600 μm, or 200 μm to 600 μm, or 250 μm to 600 μm. , or 300 μm to 600 μm, or 400 μm to 600 μm, or 500 μm to 600 μm, or 40 μm to 550 μm, or 40 μm to 500 μm, or 40 μm to 450 μm, or 40 μm to 400 μm, or 40 μm to 350 μm, or 40 μm to 300 μm, or 40 μm to 250 μm, or 40 μm to 200 μm, or 40 μm to 150 μm, or 40 μm to 100 μm.

[0080] The moisture content of the particulate CE material used in the above-described process can have a significant effect on the properties of the resulting foamed 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 within the cross-sectional area of ​​a centerline longitudinal section of a foamed article. Cell size uniformity can be determined by the span factor of the foamed article, which can be calculated by the formula (D90-D10) / D50. In the formula, "D10" refers to the cell diameter where 10 percent of the distribution has a smaller cell size and 90% has a larger cell size. "D90" refers to the cell diameter where 90% of the distribution has a smaller cell size and 10% has a larger cell size. "D50" refers to the cell diameter where 50% of the distribution has a smaller cell size and the remaining 50% has a larger cell size.

[0081] 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 has (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 μm, less than 400 μm, or less than 300 μm; (iii) a maximum cell size of less than 800 μm, less than 700 μm, or less than 600 μm; (iv) 100 to 3000, 200 to 2000, 300 to 1500, 400 to 1000, 500 to 800, or 600 to 700 cells / cm. 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 1.25 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, or 0.75 or less.

[0082] In one embodiment, or in combination with any of the embodiments 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 has: (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) 400 cells / cm 2 Less than 300 cells / cm 2 Less than 200 cells / cm 2 Less than 100 cells / cm 2 Less than or equal to 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.

[0083] Further inventive concepts relate to processes and systems for producing pellets, foam sheets, and / or articles. Although the embodiments described herein are particularly useful in the production of cellulose ester foam sheets and articles, the embodiments can be utilized in other sheet and article manufacturing applications.

[0084] In one embodiment, or in combination with any of the embodiments mentioned herein, a biodegradable cellulose acetate foam or article can be produced that is industrially or domestically compostable. In a subclass of this class, the foam or article is industrially compostable. In a subclass of this subclass, the foam or article has a thickness of less than 6 mm. In a subclass of this subclass, the foam or article has a thickness of less than 3 mm. In a subclass of this subclass, the article has a thickness of less than 1.1 mm. In a subclass of this class, the foam or article is domestically depositible. In a subclass of this subclass, the foam or article has a thickness of less than 6 mm. In a subclass of this subclass, the foam or article has a thickness of less than 3 mm. In a subclass of this subclass, the foam or article has a thickness of less than 1.1 mm. In a subclass of this subclass, the foam or article has a thickness of less than 0.8 mm. In a subclass of this subclass, the foam or article has a thickness of less than 0.6 mm.In a subclass of this subclass, the foam or article has a thickness of less than 0.4 mm.

[0085] In one embodiment, or in combination with any of the embodiments described 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. Note, however, that the foam or article may have other, larger, sizes. For example, in some embodiments, the foam or article may have a thickness of 0.5 to 24 inches, 1 to 15 inches, or 3 to 12 inches. Alternatively, or in addition, the tray or other article may have a thickness (i.e., the thickness of the cellulose ester foam material) of 100 to 400 mils, 120 to 300 mils, or 150 to 250 mils.

[0086] 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 film disintegration test protocol, as described herein.

[0087] The composition used to produce biodegradable cellulose acetate foams may contain other additives, such as fillers, stabilizers, odor control agents, waxes, compatibilizers, biodegradation accelerators, dyes, pigments, colorants, lubricants, antioxidants, viscosity modifiers, antifungal agents, heat stabilizers, antibacterial agents, softeners, mold release agents, UV absorbers, and combinations thereof. Each additional additive may be present in the cellulose ester-based material in an amount of less than 10% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, or less than 1.0% by weight. Note that the same type of compound or material may be identified or included for multiple categories of components in a cellulose acetate composition. For example, polyethylene glycol (PEG) may function as a plasticizer or as an additive that does not function as a plasticizer, such as a hydrophilic polymer or a biodegradation accelerator; for example, low-molecular-weight PEG has a plasticizing effect, while high-molecular-weight PEG functions as a hydrophilic polymer but does not have a plasticizing effect.

[0088] In one embodiment, or in combination with any other embodiment mentioned herein, the foam, composition, or foamable composition further comprises a photodegradation catalyst. In a class of this embodiment, the photodegradation catalyst is titanium dioxide or iron oxide. In a subclass of this class, the photodegradation catalyst is titanium dioxide. In a subclass of this class, the photodegradation catalyst is iron oxide.

[0089] In one embodiment, or in combination with any other embodiment mentioned herein, the foam, composition, or foamable composition further comprises a pigment. In a class of this embodiment, the pigment is titanium dioxide, carbon black, or iron oxide. In a subclass of this class, the pigment is titanium dioxide. In a subclass of this class, the pigment is carbon black. In a subclass of this class, the pigment is iron oxide. In a subclass of this class, the pigment is a biodegradable particulate natural filler.

[0090] definition It should be understood that the following is not intended to be an exhaustive list of defined terms. Other definitions may be provided in the preceding description, for example, when accompanying the use of a defined term in context.

[0091] As used herein, the terms "a," "an," and "the" mean one or more.

[0092] As used herein, the terms "comprising," "comprises," and "comprise" are open-ended transitional phrases used to transition the subject matter listed before the term to one or more elements listed after the term, and the element(s) listed after the transitional phrase are not necessarily the only elements that make up the subject matter.

[0093] To be considered "compostable," a material must meet four criteria: (1) the material must pass the biodegradation requirements when tested under controlled composting conditions at high temperature (58°C) according to ISO 14855-1 (2012), which corresponds to an absolute 90% biodegradation or a relative 90% biodegradation to a control polymer; (2) the material must reach 90% disintegration when tested under aerobic composting conditions 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); (4) the material must not adversely affect plant growth.

[0094] As used herein, the term "biodegradability" generally refers to the biological transformation and consumption of organic molecules. Biodegradability is an inherent property of the material itself, and materials may exhibit different degrees of biodegradability depending on the specific conditions to which they are exposed. The term "disintegrability" refers to the tendency of a material to physically break down into smaller pieces when exposed to specific conditions. Disintegration depends on both the material itself and the physical size and composition of the article being tested. Ecotoxicity measures the effect of a material on plants, and the heavy metal content of a material is determined according to procedures set forth in standard test methods.

[0095] To be considered "biodegradable," a material must exhibit at least 90 percent total biodegradation under home composting conditions (e.g., compared to the initial sample), or at least 90 percent of the maximum degradation of an appropriate reference material after reaching a plateau for both the reference and test items, according to French standard NFT51-800 and Australian standard AS5810. The maximum test period for biodegradation under home composting conditions is one year.

[0096] To be considered "biodegradable" under industrial deposition conditions according to ASTM D6400 and ISO 17088, at least 90% of the organic carbon in the whole article (or in each component present in an amount greater than 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), materials must demonstrate a total biodegradation of at least 90 percent, or at least 90 percent of the maximum degradation of an appropriate reference material after reaching a plateau for both the reference and test items. The maximum test period for biodegradability under industrial deposition conditions is 180 days.

[0097] To be considered "biodegradable" under soil composting conditions according to Vincotte's OK Biodegradable Soil Compliance Mark and DIN CERTCO's DIN Geprruft Biodegradable Soil Certification Scheme, a material must demonstrate a total biodegradation of at least 90% (e.g., compared to the initial sample) or at least 90 percent of the maximum degradation of an appropriate reference substance after reaching a plateau for both the reference and test items. The maximum test period for biodegradation under soil composting conditions is 2 years.

[0098] Claims not limited to the disclosed embodiments The above-described preferred embodiments of the present invention are merely used as an illustration and should not be used to limit the scope of the present invention. Modifications to the above-described exemplary embodiments can be easily made by those skilled in the art without departing from the spirit of the present invention.

[0099] The inventors hereby express their intention to rely on the doctrine of equivalents to determine and assess the reasonably fair scope of the invention as it relates to any apparatus that falls outside the literal scope of the invention as set forth in the following claims without materially departing from that scope.

[0100] Experimental Section Abbreviation h is the hour(s), Tg is the glass transition temperature, and °C is the degree(s) of Celsius.

[0101] Prior to titration to determine moisture levels, moisture was measured by Karl Fischer using 1.5 gram samples and a temperature of 180°C. The samples listed below were dried at 60°C for the times indicated. The Karl Fischer testing process for solid materials uses a Metrohm 874 Oven Sample Processor and a coulometric KF cell. Each sample was weighed (0.5-1.0 g) and placed in a 5 ml vial, then capped. Each sample group included three empty vials as atmospheric blanks, which were prepared in the same location as the samples were sealed in the vials. The Oven Sample Processor heated each sample to a target temperature of 180°C. Nitrogen served as a carrier gas, transporting any moisture released by the sample at the target temperature into the coulometric cell for titration. Results were calculated using the following formula:

[0102]

number

[0103] [Table 1]

[0104] Compounded cellulose acetate can be dried through desiccant drying systems designed to dry other polymers. Desiccant drying systems tend to be problematic when the polymer absorbs more than 1 wt% moisture, as the desiccant becomes saturated with moisture and the bed cannot regenerate quickly enough to prevent the dew point from rising. As the dew point rises, drying efficiency decreases, the drying rate tends to decrease, and moisture loss tends to slow or even stop. One way around this is to incorporate a hot air process. In this process, air is heated and passed over the pellets, expelling volatiles outside the process. In the hot air process, drying is not a closed loop, and excess moisture is expelled from the process. Once the moisture content drops below 1 wt%, a desiccant drying process can be used to further reduce the moisture content.

[0105] The desiccant drying process involves the use of hot air (50-70°C) to dry the pellets and a closed-loop system with an after-cooler and volatile trap. The volatile trap is designed to use cooling water at a temperature lower than room temperature to extract volatile materials (e.g., processing aids / plasticizers) that may alter the desiccant bed.

[0106] The base formulation is cellulose acetate with a DS of 2.5. The polymer is plasticized with triacetin, polyethylene glycol, or triethyl citrate at the following target levels:

[0107] [Table 2]

[0108] The moisture content of the following samples was measured using an Aboni Hydrotracer, where evaporating water reacts with calcium hydride, which is then converted to hydrogen gas, which is then used to measure the water concentration:

[0109] Porosity analysis plays an important role in evaluating foam materials. Our approach utilizes SEM image analysis of foam cross sections to assess porosity. To address the challenges posed by the amorphous nature of pores and potential boundary blurring or fragmentation, we developed a fully automated porosity evaluation method that combines three key image processing techniques. First, intensity thresholding is applied to separate darker pores from cell walls. Second, edge detection is used to capture edges between adjacent pores and refine the segmentation. Finally, a watershed algorithm is utilized to accurately separate connected pores by simulating water flowing into adjacent regions from different directions. By combining these techniques, our automated approach improves segmentation, increasing both the statistical representativeness and accuracy of pore size analysis. This comprehensive method provides valuable insights into the porosity characteristics of foam materials and facilitates the design of foam products with enhanced properties.

[0110] The formulation used to prepare the foam sheets was as follows: cellulose acetate blend [Eastman Cellulose Acetate FE700, triacetin (20 wt%), epoxidized soybean oil (1 wt%), diverphos 9228T (0.15 wt%)] + 1 wt% CBA (Foamazol 73S) + 1 wt% talc + 2.3 wt% pentane.

[0111] Foam sheets were produced on a tandem extrusion line. The first extruder was a twin-screw ZE30 extruder manufactured by Krauss-Maffei. The second extruder was a single-screw KE60 extruder, also manufactured by Krauss-Maffei. The physical blowing agent (pentane) was injected into barrel zone 4 of the twin-screw extruder. The foam was extruded at 40 kg / h. The ZE30 extruder set the zone temperature to 190-220°C to melt the polymer and inject gas. The cooling extruder (KE60) temperature was set to 170-190°C. The material was extruded over a 160 mm diameter mandrel, resulting in a blow-up ratio of 3.2 times the die diameter.

[0112] The foamed sheets exhibited moderate levels of corrugation at moisture contents of 10,000 ppm and severe levels at moisture contents above 20,000 ppm. Corrugation was mild and acceptable below 10,000 ppm, and no corrugation was present below 1,000 ppm. At moisture contents above 20,000 ppm, thicknesses of 4 mm or greater could not be achieved.

[0113] The density of all foams produced was 0.12 g / cm 3 It was less than.

[0114] [Table 3]

[0115] [Table 4]

[0116] The material was packaged off the production line in foil-lined bags and moisture samples were tested. Moisture was analyzed using an OmniMark moisture analyzer, which monitors weight loss as a function of time to calculate moisture loss. The unit was programmed with a standby temperature of 40°C and a test temperature of 105°C, monitoring the rate of decay to determine when the test was complete. The test program had a rate of change of 0.035% per minute, and the product was tested until the slop criteria were met.

[0117] Each sample reported below is from a lot of 10 to 30 boxes, depending on production. Moisture content reported is the average of the boxes measured as part of that lot.

[0118] [Table 5]

Claims

1. 1. A method of shaping a dry particulate material, comprising: (a) providing an expandable granular composition comprising a cellulose ester and a plasticizer, the expandable granular composition having a moisture content; (b) introducing the expandable granular composition into a drying system, thereby reducing the moisture content and forming the dry granular material; Including, the drying system includes contacting the composition with a dry steam stream passing through the drying system, the dry steam stream being discharged until the moisture content is 1% by weight or less; the dry vapor stream is air; The method wherein the expandable granular composition is dried in the drying system at a temperature at least 60°C below the Tg of the composition, but not exceeding 80°C, not exceeding 70°C, or not exceeding 60°C.

2. 10. The method of claim 1, wherein the introducing further comprises: (b) drying the expandable granular composition by circulating the dry steam stream through a closed-loop desiccant drying system after the expandable granular composition reaches a moisture content of 1% by weight or less.

3. 3. The method of claim 1, wherein the starting moisture content is 8% by weight or less or 6% by weight or less.

4. 4. The method of claim 1, further comprising cooling and at least partially condensing a portion of the dry vapor stream, thereby forming a condensate comprising volatile components entrained in the dry vapor stream.

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

6. 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 of 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. 8. The method of any one of claims 1 to 7, wherein the moisture content of the dry particulate material is 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, as measured by one or both of Karl Fischer titration and / or the use of a moisture measuring device to determine absolute moisture content.

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

10. 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 to 600, triethyl citrate, or a mixture thereof.

11. 10. The method of any one of claims 1 to 9, wherein the composition further comprises stabilizers, physical blowing agent(s), chemical blowing agent(s) (and / or precursors), nucleating agent(s), surface-modifying additive(s), pigment(s), filler(s), and / or other additive(s).

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

8.

13. 13. A particulate material prepared by the method of any one of claims 1 to 12, wherein the moisture content of the particulate material is 2000 ppm or less as measured by one or both of Karl Fischer titration and / or the use of a moisture measuring device to determine absolute moisture content.

14. A foam sheet forming process comprising: introducing a particulate material comprising a cellulose ester and having a moisture content of 200 ppm to 5000 ppm into a foam sheet extrusion process; (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) 1 cm ２ cell density of 100-3000 cells per (v) a surface roughness R of less than 50 microns ｒｍｓ and / or (vi) a cell span factor of 1.25 or less; and producing a foam sheet having one or more of: The foam sheet forming process.

15. introducing a particulate material comprising a cellulose ester and having a moisture content of 200 ppm to 5000 ppm into a foam sheet extrusion process; (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 to 10.5 ｒｍｓ , and (vi) a cell span factor of 1.25 or less; and producing a foam sheet having the formula:

15. The foam sheet forming process of claim 14, comprising:

16. The foam sheet is 1 cm ２ 16. The foam sheet forming process of claim 15, wherein the foam has a cell density of 5,000 to 17,000 cells per 1000 sieve.

17. 1. A method of packaging a particulate material, comprising: (a) providing an expandable granular composition comprising a cellulose ester and a plasticizer, the expandable granular composition having a moisture content of 3000 ppm or less; (b) introducing the particulate composition into a moisture-proof package to contain the composition therein; The method comprising:

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

19. 19. The method of any one of claims 17 to 18, wherein the expandable granular composition is treated in a drying system comprising contacting the expandable granular composition with a dry steam stream passing through the drying system, and wherein the dry steam stream is discharged until the moisture content is 1% by weight or less.

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

21. 21. The method of any one of claims 17 to 20, further comprising drying the expandable granular composition after the expandable granular composition reaches a moisture content of 1% by weight or less by circulating the dry steam stream in a closed-loop desiccant drying system.

22. 22. The method of any one of claims 17 to 21, wherein the moisture content of the dry particulate material is 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, as measured by one or both of Karl Fischer titration and / or the use of a moisture measuring device to determine absolute moisture content.

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