Blow-up ratio in foamed sheet production process

Abstract

Compositions, systems, and methods for foam sheet production processes. Such methods generally include extruding the composition and drawing the extrudate through a forming mandrel. The ratio of the forming mandrel diameter to the extruder die diameter is referred to as "blow-up ratio" (BUR). Compositions, systems, and methods according to embodiments are directed to blow-up ratios in cellulose ester foam sheet production with the aim of providing maximum sheet production yields without cracking extrudate material.

Description

Background Art

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

[0002] In the foam sheet production method, the composition of the traction extrusion is usually passed through a forming mandrel. In the conventional method using polystyrene, the blow-up ratio (that is, the ratio of the forming mandrel diameter to the extruder die diameter) can be in the range of 4 to 5. However, different compositions (such as cellulose ester compositions) can have different acceptable blow-up ratios to avoid material rupture. Therefore, it is desirable to find an acceptable blow-up ratio for cellulose ester compositions and to find a composition and method for increasing the blow-up ratio of cellulose ester compositions, thereby improving the output of foam sheet materials. Summary of the Invention

[0003] In one embodiment or in combination with any other embodiment mentioned herein, a method of forming a foam sheet is provided, comprising: (a) extruding a composition comprising a cellulose ester through an annular die having an inner diameter (X) to form a tubular extrudate; and (b) drawing the tubular extrudate over a forming mandrel having an outer diameter of 2.1X to 3.9X.

[0004] In one embodiment or in combination with any other embodiment mentioned herein, a method of forming a foam sheet is provided. The method comprises: (a) extruding a composition comprising a cellulose ester through an annular die having an inner diameter (X) of the die to form a tubular extrudate; and (b) drawing the tubular extrudate over a forming mandrel having an outer diameter of at least 3.3X.

[0005] In one embodiment or in combination with any other embodiment mentioned herein, a method of forming a foam sheet is provided. The method comprises: (a) extruding a composition through an annular die having an inner diameter (X) of the die to form a tubular extrudate; and (b) drawing the tubular extrudate over a tapered forming mandrel comprising a first end proximal to the annular die having a first diameter (Y) and a second end distal to the annular die having a second diameter, wherein the second diameter (Y) is at least 3.3X and the first diameter (Y) is smaller than the second diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1is a schematic diagram illustrating a process for forming a biodegradable article according to an embodiment of the present invention;

[0007] Figure 2 is a schematic diagram illustrating another process for forming a biodegradable article according to an embodiment of the present invention;

[0008] Figure 3 This is a diagram illustrating a method for use in accordance with an embodiment of the present invention. Figure 1 and / or Figure 2 Schematic diagram of the extrusion section in the product forming process;

[0009] Figure 4 This is a diagram illustrating a method for use in a Figure 1 and Figure 2 A schematic diagram of another extrusion section in the product forming process;

[0010] Figure 5 This is a diagram illustrating a method for use in a Figure 1 and / or Figure 2 a schematic diagram of a sheet forming section in a product forming process; and

[0011] Figure 6 is a schematic diagram illustrating an exemplary forming mandrel including heat transfer conduits adjacent to a surface of the mandrel according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] Embodiments generally relate to methods, systems, and compositions for forming biodegradable particulate materials (e.g., pellets), foam sheets, and articles. In certain embodiments, the methods, systems, and compositions described herein provide acceptable and optimal blow-up ratios when drawing a cellulose ester melt composition over a forming mandrel in a foam sheet forming process. In some of the same or other embodiments, the blow-up ratio can be increased by method and composition additives that, for example, increase the elasticity and / or melt strength of the molten composition. Exemplary methods including the methods, systems, and compositions are depicted in Figures 1-6 and described in more detail below.

[0013] Methods and systems

[0014] like Figure 1 and Figure 2As shown, raw materials can be introduced into a biodegradable polymer production process, and the process produces a biodegradable polymer material. In one embodiment or in combination with any other embodiment mentioned herein, the biodegradable polymer material comprises one or more cellulose esters. The one or more cellulose esters can include cellulose acetate. In such embodiments, the raw materials can include pulp, such as wood pulp and / or cotton pulp. The pulp can be a dissolving grade pulp and / or a paper grade pulp. The cellulose in the pulp can be esterified, for example, with acetic acid to form a biodegradable cellulose ester polymer, such as a cellulose acetate polymer.

[0015] The biodegradable polymer material can then be introduced into a compounding process, wherein the biodegradable polymer material can be mixed with a plasticizer and optionally one or more other additives (e.g., stabilizers) and a compounded material comprising the plasticized biodegradable polymer is formed. Other additives can also be mixed with the polymer and plasticizer. For example, Figure 2 As shown, other materials (additives) may include but are not limited to stabilizers, one or more physical foaming agents, one or more chemical foaming agents (and / or precursors), one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers and / or one or more other additives. Other additives may include, for example, surface modification additives (e.g., slip agents) and / or functional ion components. In one embodiment or in combination with any other embodiment mentioned herein, biodegradable polymers may be mixed with components having one or more glass transition temperatures (Tg) lower than room temperature (about 20°C). Additionally or alternatively, biodegradable polymers may include one or more other polymers and / or additives that may increase the elasticity and / or melt strength of the composition and / or reduce the Tg of the composition. Further details of the polymers and additives that may be included in the composition are provided below. Mixing may be accomplished by any known mixing technique, including but not limited to rolling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling.

[0016] The compounding process may include a granulation process. The granulation process may generally include mixing a biodegradable polymer material, a plasticizer and one or more other additives to form a mixed composition, and forming a granular material from the composition. In particular, the granulation process may include a granulation process, and the granular material may include a certain amount of granules. The term "compounded CE material" means a cellulose ester material formed during the compounding process, which may include a mixture of cellulose ester, plasticizer and other additives. In addition, such compounded CE materials may be in the form of granular materials or granules. It should be understood that, as used herein, the phrase "granulation" or "granulation process" may be the same as "granulation" or "granulation process" or may at least include "granulation" or "granulation process". In some embodiments, the granulation process may include granulation into a water bath, granulation on an air cooling belt, underwater granulation, solvent compounding, etc.

[0017] In one embodiment or in combination with any other embodiment mentioned herein, the plasticizer and one or more other additives can be mixed with the cellulose ester by conventional melt compounding techniques, which involve combining the cellulose ester with the plasticizer and, optionally, other additives, at appropriate temperature and pressure in a twin-screw extruder with appropriate mixing elements to obtain a molten, uniformly combined cellulose ester mixture when the material leaves the extruder. The molten compounded cellulose ester mixture can then be extruded through a die having an orifice with a diameter of about 2-6 mm to extrude a strand. This strand can then be cooled by water (e.g., by underwater pelletizing) or air and cut at regular intervals to provide a uniform and desired size and shape, referred to as "pellets" or "particulates." Although methods for forming granulated compounded materials are described herein, it will be understood that, according to some embodiments, the compounded material fed to the foam sheet production process can be in any physical form (e.g., pellets, powders, particulates, fibers). The term "compounded CE material" means the cellulose ester material formed during the compounding process, which can include a mixture of cellulose ester, plasticizer, and other additives. Furthermore, such compounded CE materials may be in the form of a melt mixture or a particulate material (eg, pellets, powder, granules, fibers, etc.).

[0018] like Figure 1 and Figure 2 As shown, the compounded CE material, which may include pellets of a plasticized biodegradable polymer as described above, may then be introduced into a foam sheet production process. The foam sheet production process may include one or more zones / steps for producing foam sheets or films, which are described in more detail below. Although an exemplary foam sheet production process is described herein, it should be understood that certain aspects described herein may also be applicable to rigid (i.e., non-foam) materials and articles. Figure 1As shown, in one embodiment or in combination with any other embodiment mentioned herein, various additives can be introduced into one or more zones of the foam sheet production process. The additives can include, but are not limited to, stabilizers, one or more physical blowing agents, one or more chemical blowing agents (and / or precursors), one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0019] The foam sheet production process may generally include an extrusion section and a sheet forming section. Figure 3 An exemplary extrusion section is depicted. As shown, the extrusion section may include a feed preparation zone, wherein solid additives may be combined with the compounded CE materials and introduced into the downstream extrusion zone. In one embodiment or in combination with any other embodiment mentioned herein, the feed preparation zone may include a feed hopper. Thus, the compounded CE materials and other solid additives may be stored in a feed hopper, which introduces the combined feed composition into the extrusion zone. The feed preparation zone may further include a mixer, wherein the compounded CE materials and one or more additives may be mixed before being introduced into the hopper. Mixing may be accomplished by any known mixing technique, including but not limited to rolling in a cylindrical container, overhead stirring, sigma blade mixing, and tumbling. One or more exemplary solid additives that may be combined with the compounded materials may include one or more chemical foaming agents, one or more nucleating agents, one or more surface modification additives, one or more pigments, one or more fillers, and / or one or more other additives.

[0020] The combined feed composition from the feed preparation zone can then be introduced into the extrusion zone. The extrusion zone can typically include one or more extruders, which can include single-screw extruders and / or twin-screw extruders. Within the one or more extruders, the feed composition can be introduced into the extruder barrel and conveyed through a die via one or more screws, which forms an extrudate from the feed composition. As the composition is conveyed to the die through the extruder barrel, it can be heated and at least partially melted. Therefore, the term "CE melt composition" as used herein refers to a cellulose ester-based feed composition that has been melted into a flowable molten resin by the extrusion section. Heating can be supplied by an external heater positioned along the outside of the extruder barrel. The shape of the extrudate will typically depend on the shape and size of the die head. As described below, the extrudate can be further shaped by downstream processes.

[0021] While in the extruder, one or more additives may be introduced into the CE melt composition.For example, one or more physical blowing agents may be added to the CE melt composition by injecting the physical blowing agent into the composition as it is conveyed in the extruder barrel.

[0022] As Figure 4 depicted, in one embodiment or in combination with any other embodiment mentioned herein, the extrusion zone can include a primary extrusion vessel and a cooling vessel. The primary extrusion vessel and the cooling vessel can be separate devices or combined into a single apparatus. Regardless, the feed composition from the feed preparation zone is introduced into the primary extrusion vessel and at least partially melted as it is conveyed through the extruder barrel as described above, 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 a blowing agent can be added to the CE melt composition as it is conveyed through the primary extrusion vessel.

[0023] The CE melt composition from the primary extrusion vessel is then introduced into the cooling vessel. The cooling vessel can be a secondary extrusion vessel that is operated similarly to the primary extrusion vessel but at a lower temperature than the primary extrusion vessel. Within the cooling vessel, the CE melt composition can be further mixed to provide a substantially uniform mixture of the melt polymer and one or more other additives. The CE melt composition can then be directed through a die and exit the die head to provide a cellulose ester-based extrudate that can be further processed in a sheet forming section of the foam sheet production process. In one embodiment or in combination with any other embodiment mentioned herein, the CE melt composition exiting the die head can have a temperature of at least 150 °C, at least 160 °C, at least 170 °C, at least 180 °C, at least 190 °C, at least 200 °C, about 150 °C to about 220 °C, and / or about 170 °C to about 200 °C.

[0024] As Figure 4 depicted, one or more filter devices can be installed within the extrusion section to filter and remove particulate matter from the CE melt composition. For example, a screen changer filter device can be installed at the downstream end of the primary extrusion vessel and the secondary extrusion vessel, which can remove solid components from the CE melt composition prior to directing the CE melt composition through the die head to the sheet forming section.

[0025] The sheet forming section can include any of the systems and methods for forming the extrudate into a cellulose ester material sheet that can be used for article forming. The shape of the extrudate will depend on the shape of the die head generally, and the shape of the sheet formed in the sheet forming section can depend on the shape of the die head and other downstream processes. For example, the extrudate can have a generally flat shape, or it can be annular and undergo further processing to form a flat sheet. In the embodiment in which the die has an annular shape, the die can have a diameter of 1 to 40 cm, 2 to 20 cm, 2 to 10 cm and / or 3 to 8 cm. In addition, the size of the thickness of the opening (referred to in this article as "die gap") from which the extrudate ejects can generally be 0.1 to 6.0 mm, 0.1 to 3.0 mm and / or 0.1 to 1.0 mm.

[0026] Figure 5 An exemplary sheet forming section is depicted in . As shown, the CE molten composition is extruded through an annular die and pulled through a forming mandrel. A cooling fluid (e.g., air) can flow through the interior and / or exterior of the extrudate to cool the extrudate material as it passes through the mandrel. For example, a cooling fluid can be blown from the mandrel to the die to cool the inner surface of the extrudate between the die and the mandrel. Additionally or alternatively, a cooling fluid can flow through the mandrel to cool the outer surface of the extrudate as it passes through the mandrel. In some embodiments, the tubular extrudate is cooled by a cooling ring positioned around the mandrel. In certain embodiments, the cooling ring is positioned at a distance of at least 1 foot, at least 2 feet, or at least 3 feet from the annular die. A heated gaseous (steam) stream (e.g., air) can be fed through an interior portion of the mandrel, for example, to ensure that the extrudate remains sufficiently aerated so that the extrudate can be continuously pulled through the mandrel, such as Figure 6 In some embodiments, the heated vapor stream may comprise air, nitrogen, or carbon dioxide, although other gaseous components may also be used.

[0027] Temperature control of the extrudate being pulled through the mandrel has an important impact on the size limit of the extrudate and the properties of the resulting foam. In one embodiment or in combination with any other embodiment mentioned herein, the temperature of the extrudate material can be maintained at a temperature above the glass transition temperature of the extrudate material in the region between the extruder die and the mandrel. In some embodiments, the CE melt composition has a glass transition temperature (Tg) and is extruded through the annular die at a temperature of at least 40°C, at least 60°C, at least 70°C, at least 80°C, at least 90°C, or at least 100°C higher than the Tg of the CE melt composition. In some embodiments, a heated steam stream can be introduced into the space between the annular die and the forming mandrel at a temperature of 30°C to 150°C or 60°C to 120°C. In some embodiments, the heated steam stream has a relative humidity (RH) of at least 10%, at least 20%, at least 30%, at least 40%, or at least 50%. In some such embodiments, a heated steam stream can be used to add moisture to the extrudate because the water vapor in the gas stream contacts the extrudate as it exits the die and is drawn over the forming mandrel.

[0028] In one embodiment or in combination with any other embodiment mentioned herein, the extrudate is drawn past the outer surface of a forming mandrel, which is maintained at a temperature greater than 30°C. The surface may be maintained at a temperature of at least 40°C, at least 50°C, or at least 60°C. In some embodiments, the temperature may be controlled by providing heat from one or more electric heating elements at least partially positioned adjacent to the surface. For example, one or more heating elements and / or one or more insulating elements may be at least partially positioned around the space between the annular die and / or the forming mandrel. In some embodiments, the one or more heating elements comprise an infrared (IR) heater. Additionally or alternatively, the temperature may be controlled by flowing a heat transfer medium (heat transfer fluid) through a conduit at least partially positioned adjacent to the surface so as to provide indirect heat transfer between the heat transfer medium and the surface.

[0029] Figure 6 An exemplary forming mandrel is shown, comprising a heat transfer conduit adjacent to the mandrel surface. During operation, a heat transfer medium can be introduced into the conduit and flowed through the conduit surrounding the inner side of the mandrel surface. The temperature of the heat transfer medium introduced into the conduit can be adjusted as needed to maintain a desired surface temperature of the mandrel. Exemplary heat transfer fluids can include air, water, oil, glycols, and mixtures thereof, but it should be understood that other suitable heat transfer fluids can also be used.

[0030] The composition of extrudate material and temperature may affect the blow-up ratio (BUR) of the extrudate material being pulled through forming mandrel. As used herein, term " blow-up ratio " means the ratio of the internal diameter of extruder die head and the external diameter of outer mandrel. In one embodiment or in the combination with any other embodiment mentioned herein, with 2.0 to 4.0,2.1 to 3.9,2.2 to 3.8,2.3 to 3.7,2.4 to 3.6,2.5 to 3.5 blow-up ratio pulling extrudate through forming mandrel, but can achieve even higher blow-up ratio in some embodiments. Therefore, in some embodiments, annular die has die head internal diameter (X), and pulling extrudate is through the forming mandrel with the mandrel external diameter of at least 3.3X, at least 3.4X, at least 3.5X, at least 3.6X, at least 3.7X, at least 3.8X, at least 3.9X or at least 4.0X. In some embodiments, the extrudate is pulled through a forming mandrel having a mandrel outer diameter of at least 2.0X, at least 2.1X, at least 2.2X, at least 2.3X, at least 2.4X, or at least 2.5X and / or no more than 4.0X, no more than 3.9X, no more than 3.8X, no more than 3.7X, no more than 3.6X, or no more than 2.5X.

[0031] One or more specific cellulose esters and other polymers and / or additives in the CE melt composition may affect the maximum limit of BUR without causing the extrudate material to break. This limit may be affected by the inherent draw ratio and / or melt strength of the composition. In some embodiments, the CE composition comprises cellulose acetate, which in some embodiments may have an optimal BUR of 2.1 to 3.9. In some embodiments, one or more polymers that are miscible or dispersible in cellulose acetate may be included to increase the maximum limit of BUR of the material. In some such embodiments, the miscible or dispersible polymers are selected from polyethylene succinate (PES), poly(glycolic acid) (PGA) and starch (including modified starch). In some embodiments, the CE composition may comprise biodegradable aliphatic polyesters and mixed esters, thereby allowing even higher BURs without causing the extrudate material to break. For example, a CE composition comprising cellulose acetate propionate (CAP), polylactic acid (PLA) and / or polybutylene succinate (PBS) may be able to achieve a BUR of 4.0 or higher. Other polymer blends may also be able to achieve similar BURs. Other additives may also be included, such as chemical blowing agents, physical blowing agents, co-blowing agents, surface modification additives, elastomeric polymers (e.g., PEG), and melt strength enhancers (e.g., ionic functional components) that increase the potential maximum limit of the BUR of the CE composition. The polymers and additives in the CE composition are described in more detail below.

[0032] In one embodiment or in combination with any other embodiment mentioned herein, the forming mandrel is tapered so that the first end near the annular die has a first diameter and the second end away from the annular die has a second diameter. In some embodiments, the first diameter is less than the second diameter so that when the extrudate is pulled from the first end to the second end through the forming mandrel, the extrudate expands to a higher BUR. For example, the first end has a first diameter (Y) and the second end has a second diameter of at least 1.1Y, at least 1.2Y, at least 1.3Y, at least 1.4Y, at least 1.5Y, at least 1.6Y, at least 1.7Y, at least 1.8Y, at least 1.9Y or at least 2.0Y. In some embodiments, the first end has a first diameter (Y) and the second end has a second diameter of 1.1Y to 3.0Y, 1.2Y to 2.8Y, 1.3Y to 2.6Y, 1.4Y ​​to 2.4Y, 1.5Y to 2.2Y or 1.6Y to 2.0Y. The specific ratio of the tapered mandrel diameters can depend on a variety of factors, such as the mandrel length and the composition of the extrudate. In some embodiments, the second end has a diameter of at least 3.3X, at least 3.4X, at least 3.5X, at least 3.6X, at least 3.7X, at least 3.8X, at least 3.9X, or at least 4.0X (i.e., the ratio (X) of the second end diameter to the die inner diameter). In some embodiments, the second end has a diameter of 2.0X to 4.0X, 2.1X to 3.9X, 2.2X to 3.8X, 2.3X to 3.7X.

[0033] The length of forming mandrel will depend on the elasticity of extrudate generally, and the elasticity of described extrudate depends on multiple factors, such as composition, temperature etc., as described herein.Especially, selected one or more blowing agents can have a significant impact on the appropriate length of forming mandrel.For example, comprising CO2 as the composition of blowing agent can need a shorter forming mandrel than the composition comprising larger hydrocarbon blowing agent.Not bound by any theory, it is believed that the internal pressure from blowing agent keeps the extrudate from contracting laterally.Due to CO2 diffusion from the extrudate is faster than hydrocarbon (for example, pentane), therefore if being pulled through the longer mandrel of length, the extrudate will freeze (contraction).In one embodiment or with the combination of any other embodiment mentioned herein, forming mandrel has a length of 2 feet to 30 feet, 3 feet to 20 feet, 4 feet to 15 feet or 5 feet to 10 feet.In some embodiments and particularly when comprising CO2 as blowing agent, forming mandrel can have a length of 2 feet to 5 feet.

[0034] The forming mandrel can be made of a variety of materials, and its parts can be made of the same or different materials. However, the one or more materials used for the outer surface of the forming mandrel (that is, the surface through which the extrudate is pulled) may have an important process impact. For example, one or more materials of the surface can be selected to avoid being corroded, pitted, etched, etc. by certain components in the extrudate composition (such as acid (for example, acetic acid)), providing desired heat transfer characteristics, and / or having a desired friction coefficient with the extrudate composition. In some embodiments, the surface can comprise aluminum and / or stainless steel. In some embodiments, the surface can include a protective coating. Exemplary protective coatings can include carbon coatings, Teflon coatings, and chromium coatings. It is worth noting that, due to reacting with the styrene in traditional foam sheet compositions, chromium coatings are traditionally avoided in forming mandrels. However, since the composition described herein is typically a cellulose ester composition (rather than polystyrene), such reactions are not a problem. Additionally or alternatively, it is preferred to provide materials and coatings with a generally smooth surface (rather than a matte surface) so that the extrudate can be pulled more easily through the mandrel without breaking the material.

[0035] Reference again Figure 5 , the tubular extrudate can be opened using a slicer (or slitting device), which allows the tubular shape to be formed into a flat sheet. For example, the tubular extrudate passed through the mandrel can be cut and pulled to a tensioning station, which includes one or more rollers that flatten the extrudate and maintain the necessary amount of tension on the extrudate to continue pulling the extrudate onto the mandrel. The flattened extrudate will typically be in the form of a sheet, which can then be directed to a winding station where the material can be wound up for packaging and shipping.

[0036] Reference again Figure 1 and Figure 2 The sheets produced by the sheet production process can be used to form foam products, which will be described in more detail below. Such products are particularly useful in the food service industry. Exemplary products include meat trays. The products can have one or more particularly advantageous properties. For example, the products can be biodegradable and / or compostable, and / or the products can have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0037] In one embodiment or in combination with any other embodiment mentioned herein, the linear velocity ratio is 0.1 to 0.33 kg / m, or 0.1 to 0.3 kg / m, or 0.1 to 0.29 kg / m, or 0.1 to 0.28 kg / m, or 0.1 to 0.27 kg / m, or 0.1 to 0.25 kg / m, or 0.1 to 0.23 kg / m, or 0.1 to 0.22 kg / m, or 0.1 to 0.21 kg / m, or 0.1 to 0.19 kg / m, or 0.1 to 0.17 kg / m, or 0.1 to 0.15 kg / m, or 0.1 to 0.14 kg / m, or 0.12 to 0.33 kg / m g / m, or 0.12 to 0.3 kg / m, or 0.12 to 0.29 kg / m, or 0.12 to 0.28 kg / m, or 0.12 to 0.27 kg / m, or 0.12 to 0.25 kg / m, or 0.12 to 0.23 kg / m, or 0.12 to 0.21 kg / m, or 0.12 to 0.19 kg / m, or 0.12 to 0.17 kg / m, or 0.12 to 0.15 kg / m, or 0.12 to 0.14 kg / m, or 0.14 to 0.33 kg / m, or 0.14 to 0.3 kg / m, or 0.14 to 0.29 kg / m, or 0.14 to 0.28 kg / m, or 0.14 to 0.27 kg / m, or 0.14 to 0.25 kg / m, or 0.14 to 0.23 kg / m, or 0.14 to 0.21 kg / m, or 0.14 to 0.19 kg / m, or 0.14 to 0.17 kg / m, 0.16 to 0.33 kg / m, or 0.16 to 0.3 kg / m, or 0.16 to 0.29 kg / m, or 0.16 to 0.28 kg / m, or 0.16 to 0.27 kg / m, or 0.16 to 0.25 kg / m, or 0.16 to 0.23 kg / m, or 0.16 to 0.21 kg / m, or 0.16 to 0.19 kg / m m, 0.18 to 0.33 kg / m, or 0.18 to 0.3 kg / m, or 0.18 to 0.29 kg / m, or 0.18 to 0.28 kg / m, or 0.18 to 0.27 kg / m, or 0.18 to 0.25 kg / m, or 0.18 to 0.23 kg / m, or 0.18 to 0.21 kg / m, or 0.19 to 0.33 kg / m, or 0.19 to 0.3 kg / m, or 0.19 to 0.29 kg / m, or 0.19 to 0.28 kg / m, or 0.19 to 0.27 kg / m, or 0.19 to 0.25 kg / m, or 0.19 to 0.23 kg / m.

[0038] Composition

[0039] Said method can comprise preparation and extruding the composition that can be used for downstream processing to form useful goods.For example, in one embodiment or in combination with any other embodiment mentioned herein, extrusion feed material can comprise granular material, and described granular material comprises biodegradable polymer and optionally one or more additives, such as those as described herein.In one embodiment or in combination with any other embodiment mentioned herein, feed material and one or more additives (such as those as described herein) can be combined to provide the mixed composition comprising biodegradable polymer and one or more additives.In one embodiment or in combination with any other embodiment mentioned herein, biodegradable polymer comprises cellulose ester.

[0040] In one embodiment or in combination with any other embodiment mentioned herein, the cellulose ester composition includes one or more polymers and / or other additives that can effectively enhance the melt strength of the composition and / or increase the elasticity of the composition. Compared to compositions without these polymers and / or additives, such polymers and other additives can allow the molten composition pulled through the forming mandrel to have an increased blow-up ratio without rupturing the extrudate. For example, in some embodiments, the composition includes 1wt% to 50wt% or 2wt% to 20wt% of one or more such polymers and / or other additives. In some embodiments, the composition includes at least one additive having a specific heat capacity of at least 1800J / kg-C or at least 2000J / kg-C. In some embodiments, the composition includes one or more additives selected from the group consisting of chemical foaming agents, physical foaming agents (e.g., hydrocarbon foaming agents), surface modification additives (e.g., slip agents), biodegradable polymers (e.g., polyethylene glycol (PEG) and other biodegradable polymers described herein) and / or melt strength enhancers (such as functional ion components).

[0041] Additional details of the composition components, including biodegradable polymers (eg, cellulose esters) and other additives, are provided below.

[0042] cellulose esters

[0043] The cellulose esters used as described herein can be any of those known in the art. Cellulose esters useful in embodiments herein typically comprise repeating units of the following structure:

[0044]

[0045] Wherein R1, R2 and R3 are independently selected from hydrogen, acetyl, propyl or butyl. The substitution level of cellulose esters is usually expressed as the degree of substitution (DS), which is the average number of non-OH substituents per anhydroglucose unit (AGU). Typically, conventional cellulose contains three hydroxyl groups that can be substituted in each AGU unit; therefore, the value of DS can be between zero and three. Natural cellulose is a large polysaccharide with a degree of polymerization of 250-5,000 even after pulping and purification, and therefore the assumption that the maximum DS is 3.0 is roughly correct. Since DS is a statistical average, a value of 1 does not guarantee that each AGU has a single substituent. In some cases, there may be unsubstituted anhydroglucose units, some with two substituents and some with three substituents, and typically, the value will be a non-integer. The total DS is defined as the average number of all substituents per anhydroglucose unit. The degree of substitution per AGU can also refer to a specific substituent, such as, for example, a hydroxyl group or an acetyl group. In one embodiment or in combination with any other embodiments, n is an integer ranging from 25 to 250, or from 25 to 200, or from 25 to 150, or from 25 to 100, or from 25 to 75.

[0046] In one embodiment or in combination with any other embodiment, the cellulose ester has at least 2 anhydroglucose rings and can have between at least 50 and up to 5,000 anhydroglucose rings or between at least 50 and less than 150 anhydroglucose rings. The number of anhydroglucose units per molecule is defined as the degree of polymerization (DP) of the cellulose ester. In one embodiment or in combination with any other embodiment, the cellulose ester can have an intrinsic viscosity (IV) of about 0.2 to about 3.0 deciliters per gram, or about 0.5 to about 1.8, or about 1 to about 1.5, measured for a 0.25 gram sample in 100 ml of a 60 / 40 weight solution of phenol / tetrachloroethane at a temperature of 25°C. In one embodiment or in combination with any other embodiment, the cellulose ester useful herein can have a DS / AGU of about 1 to about 3.0, 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 an acetyl group.

[0047] Cellulose esters can be produced by any method known in the art. Examples of methods for producing cellulose esters are taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th edition, Volume 5, Wiley-Interscience, New York (2004), pages 394-444. Cellulose is the starting material for producing cellulose esters and can be obtained from various grades and sources, such as cotton linters, softwood pulp, hardwood pulp, corn fiber and other agricultural sources, and bacterial cellulose.

[0048] One method for producing cellulose esters is to esterify the cellulose by mixing it with an appropriate organic acid, anhydride, and a catalyst. The cellulose is then converted into a cellulose triester. The esters are then hydrolyzed by adding a water-acid mixture to the cellulose triester, which can then be filtered to remove any gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester can then be washed with water to remove reaction by-products, followed by dehydration and drying.

[0049] The cellulose triester to be hydrolyzed may have three acetyl substituents. These cellulose esters may be prepared by many methods known to those skilled in the art. For example, cellulose esters may be prepared by the presence of a catalyst such as H2SO 4) Cellulose triesters can also be prepared by homogeneous acylation of cellulose dissolved in a suitable solvent such as LiCl / DMAc or LiCl / NMP.

[0050] Those skilled in the art will appreciate that the commercial term cellulose triesters also encompass cellulose esters that are not fully substituted with acyl groups. For example, cellulose triacetate commercially available from Eastman Chemical Company, Kingsport, TN, USA, typically has a DS of about 2.85 to about 2.99.

[0051] After cellulose is esterified to a triester, some of the acyl substituents can be removed by hydrolysis or alcoholysis to produce a secondary cellulose ester. As previously mentioned, the distribution of the acyl substituents can be random or non-random, depending on the specific method used. Secondary cellulose esters can also be prepared directly without hydrolysis by using a limited amount of acylating agent. This method is particularly useful when the reaction is carried out in a solvent that will dissolve the cellulose. All of these methods produce cellulose esters useful in the present invention.

[0052] In one embodiment or combination with any of the recited embodiments, the cellulose acetate is cellulose diacetate having a polystyrene equivalent number average molecular weight (Mn) of about 10,000 to about 100,000 as measured by gel permeation chromatography (GPC) using NMP as a solvent and a polystyrene equivalent according to ASTM D6474. In one embodiment or combination with any of the other embodiments, the cellulose acetate composition comprises cellulose diacetate having a polystyrene equivalent number average molecular weight (Mn) of about 10,000 to about 100,000 as measured by gel permeation chromatography (GPC) using NMP as a solvent and a polystyrene equivalent according to ASTM D6474. 10,000 to 90,000; or 10,000 to 80,000; or 10,000 to 70,000; or 10,000 to 60,000; or 10,000 to less than 60,000; or 10,000 to less than 55,000; or 10,000 to 50,000; or 10,000 to less than 50,000; or 10,000 to less than 45,000; or 10,000 to 40,000; or 10,000 to 30,000; or 20,000 to less than 60,000; or 20,000 to less than 55,000; or 20, or 30,000 to less than 60,000; or 30,000 to less than 55,000; or 30,000 to 50,000; or 30,000 to less than 50,000; or 30,000 to less than 45,000; or 30,000 to 40,000; or 30,000 to 35,000; or 20,000 to 30,000; or 30,000 to less than 60,000; or 30,000 to less than 55,000; or 30,000 to 50,000; or 30,000 to less than 50,000; or 30,000 to less than 45,000; or 30,000 to 40,000; or 30,000 to 35,000.

[0053] The most common commercial secondary cellulose esters are produced by an initial acid-catalyzed heterogeneous acylation of cellulose to form cellulose triesters. After obtaining a homogeneous solution of the cellulose triesters in the corresponding carboxylic acid, the cellulose triesters are then subjected to hydrolysis until the desired degree of substitution is achieved. After separation, random secondary cellulose esters are obtained. That is, the relative degree of substitution (RDS) of each hydroxyl group is approximately equal.

[0054] The cellulose esters useful in the present invention can be prepared using techniques known in the art and can be selected from various types of cellulose esters, such as, for example, cellulose esters available from Eastman Chemical Company, Kingsport, TN, USA, e.g., Eastman TM Cellulose acetate CA 398-30 and Eastman TMCellulose acetate CA 398-10, Eastman TM CAP 485-20 Cellulose acetate propionate; Eastman TM CAB 381-2 Cellulose acetate butyrate.

[0055] In one embodiment or in combination with any other embodiment, the cellulose ester can be prepared by converting cellulose to a cellulose ester with a reactant obtained from a recycled material (e.g., a recycled plastic content syngas source). In one embodiment or in combination with any other embodiment, such a reactant can be a cellulose reactant, which includes an organic acid and / or an anhydride used in an esterification or acylation reaction of cellulose, e.g., as discussed herein.

[0056] In one embodiment of the present application or in combination with any of the mentioned embodiments, or in combination with any of the mentioned embodiments, there is provided a cellulose ester composition comprising at least one recycled cellulose ester, wherein the cellulose ester has at least one substituent on a dehydrated glucose unit (AU) derived from a recycled content material (e.g., a recycled plastic content syngas).

[0057] In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises cellulose ester in an amount of 50 to 99 wt%, or 60 to 99 wt%, or 70 to 99 wt%, or 80 to 99 wt%, from 50 to 98 wt%, or 60 to 98 wt%, or 70 to 98 wt%, or 80 to 98 wt%, or 90 to 98 wt%, 50 to 90 wt%, or 60 to 90 wt%, or 70 to 90 wt%, or 80 to 90 wt%, or 90 to 99 wt%, or 50 to 80 wt%, or 60 to 80 wt%, or 70 to 80 wt%, or 50 to 70 wt%, or 60 to 70 wt%, or 50 to 60 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein can comprise a combination, blend, or mixture of two or more different types of cellulose ester. For example, in some embodiments, the cellulose ester used herein can be composed of a blend of two or cellulose esters having different DSAC; however, the blend can have a total DSAC between 2.2 and 2.8 or between 2.0 and 2.9.

[0058] Plasticizer

[0059] In one embodiment or in combination with any other embodiment, the cellulose ester composition described herein may include at least one plasticizer. Plasticizers reduce the melting temperature (i.e., Tg) and / or melt viscosity of the cellulose ester. Plasticizers for cellulose esters may include triacetin, diacetin, dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, poly (ethylene glycol) MW 200-600, dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl o-benzoylbenzoate, triethylene glycol dipropionate, 1,2-epoxypropylphenyl glycol, 1,2-epoxypropyl(m-tolyl) glycol, 1,2-epoxypropyl(o-tolyl) glycol, β-oxyethyl cyclohexenecarboxylate, diethylene glycol bis(cyclohexanecarboxylate), triethyl citrate, polyethylene glycol, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinyl pyrrolidone and tribenzoic acid glycol esters, plasticizers containing benzoates such as Benzoflex TM Plasticizer series, poly (alkyl succinates) such as poly (butyl succinate), polyethersulfone, o-toluenesulfonate, n-ethyltoluenesulfonamide, adipate-based plasticizers, soybean oil epoxides such as Paraplex TM Plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributyrin, sucrose acetate isobutyrate, Resolflex TM Series plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (e.g., ethyl phthaloyl glycolate "EPEG" and methyl phthaloyl glycolate "MPEG"), methoxy polyethylene glycol, 2,2,4-trimethylpentane-1,3-diyl bis(2-methylpropionate) and polycaprolactone. In some embodiments, the plasticizer used herein can include a combination or mixture of two or more different types of plasticizers.

[0060] In one embodiment or in combination with any other embodiment, 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.

[0061] In one embodiment or in combination with any other embodiment, the plasticizer is a food compliance plasticizer. Food compliance means meeting applicable food additives and / or food contact regulations, wherein the plasticizer is approved for use or is considered safe by at least one (national or regional) food safety regulatory agency (or organization), such as listed in 21CFR Food Additive Regulations or otherwise listed as generally recognized as safe (GRAS) by the U.S. FDA. In one embodiment or in combination with any other embodiment, the food compliance plasticizer is triacetin or polyethylene glycol (PEG) with a molecular weight of about 200 to about 600. In one embodiment or in combination with any other embodiment, examples of food-compliant plasticizers that may be considered may include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, acetyl tributyl citrate, Admex, tripropionin, Scandiflex, poloxamer copolymers, polyethylene glycol succinate, diisobutyl adipate, polyvinyl pyrrolidone, and glycol tribenzoate.

[0062] In one embodiment or combination with any other embodiment, the plasticizer is present in an amount sufficient to allow the cellulose ester composition to be melt processed (or thermoformed) into useful articles, such as disposable plastic articles, in conventional melt processing equipment. In one embodiment or combination with any other embodiment, the plasticizer is present in an amount of 1 to 40 wt% for most thermoplastic processing; or 5 to 25 wt%, or 10 to 25 wt%, or 12 to 20 wt%, based on the weight of the cellulose ester composition. In one embodiment or combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be accomplished with plasticizer levels in the range of 10-30, or 12-25, or 15-20, or 10-25 wt%, based on the weight of the cellulose ester composition.

[0063] In one embodiment or in combination with any other embodiment, the plasticizer is a biodegradable plasticizer. Some examples of biodegradable plasticizers include triacetin, triethyl citrate, acetyl triethyl citrate, polyethylene glycol, benzoate-containing plasticizers such as Benzoflex, TM Plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfones, adipate-based plasticizers, soybean oil epoxides such as Paraplex TM Plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributyrin, Res oflexTM Series of plasticizers, triphenyl phosphate, glycolate, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diylbis(2-methylpropionate) and polycaprolactone.

[0064] In one embodiment or in combination with any other embodiment, the cellulose ester composition can contain a plasticizer selected from the group consisting of PEG and MPEG (methoxy PEG). The polyethylene glycol or methoxy polyethylene glycol composition has an average molecular weight of 200 to 600 Daltons, wherein the composition is melt processable, biodegradable, and disintegratable.

[0065] 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.

[0066] 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.

[0067] In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises at least one plasticizer (as described herein) in an amount of 1 to 40 wt%, or 5 to 40 wt%, or 10 to 40 wt%, or 12 to 40 wt%, 13 to 40 wt%, or 15 to 40 wt%, or greater than 15 to 40 wt%, or 17 to 40 wt%, or 20 to 40 wt%, or 25 to 40 wt%, or 5 to 35 wt%, or 10 to 35 wt%, or 13 to 35 wt%, or 15 to 35 wt%, or greater than 15 to 35 wt%, or 17 to 35 wt%, or 20 to 35 wt%, or 5 to 30 wt%, or 10 to 30 wt%, or 13 to 30 wt%, or 15 to 30 wt%. %, or greater than 15 to 30 wt%, or 17 to 30 wt%, or 5 to 25 wt%, or 10 to 25 wt%, or 13 to 25 wt%, or 15 to 25 wt%, or greater than 15 to 25 wt%, or 17 to 25 wt%, or 5 to 20 wt%, or 10 to 20 wt%, or 13 to 20 wt%, or 15 to 20 wt%, or greater than 15 to 20 wt%, or 17 to 20 wt%, or 5 to 17 wt%, or 10 to 17 wt%, or 13 to 17 wt%, or 15 to 17 wt%, or greater than 15 to 17 wt%, or 5 to less than 17 wt%, or 10 to less than 17 wt%, or 13 to less than 17 wt%, or 15 to less than 17 wt%, all based on the total weight of the cellulose ester composition.

[0068] In one embodiment or in combination with any other embodiment, the at least one plasticizer comprises or is a food acceptable or FDA approved plasticizer. In one embodiment or in combination with any other embodiment, the food acceptable or FDA approved plasticizer comprises or is triacetin or PEG MW 300 to 500.

[0069] Biodegradable polymers

[0070] In one embodiment or in combination with any other embodiment, the cellulose ester composition described herein comprises a biodegradable cellulose ester (BCE) component comprising at least one BCE, which may include one or more of the cellulose esters described herein; and a biodegradable polymer component comprising at least one other biodegradable polymer (not BCE). In one embodiment or in combination with any other embodiment, the other biodegradable polymer can be selected from polyhydroxyalkanoates (PHA and PHB), polylactic acid (PLA), poly(glycolic acid) (PGA), polycaprolactone polymers (PCL), polybutylene adipate terephthalate (PBAT), polyethylene succinate (PES), polyvinyl acetate (PVA), polybutylene succinate (PBS) and copolymers (such as polybutylene succinate-co-adipate (PBSA)), cellulose esters, cellulose ethers, starch (including modified starch), proteins, derivatives thereof, and combinations thereof. In one embodiment or in combination with any other embodiment, the cellulose ester composition comprises two or more biodegradable polymers.

[0071] In one embodiment or in combination with any other embodiment, the cellulose ester compositions described herein comprise a blend of a cellulose ester and one or more biodegradable polymers that can enhance the melt strength and / or increase the elasticity of the composition. Particularly preferred biodegradable polymers include those having high biodegradability, a low Tg (e.g., below room temperature), and / or a low modulus.

[0072] In one embodiment or in combination with any other embodiment, the biodegradable polymer is selected from polyethylene succinate (PES), poly(glycolic acid) (PGA), starch (including modified starch), and mixtures thereof. In some such embodiments, these biodegradable polymers can provide an increased blow-up ratio when combined with cellulose acetate.

[0073] In one embodiment or in combination with any other embodiment, the biodegradable polymer is selected from polybutylene succinate (PBS) and copolymers (such as polybutylene succinate-co-butylene adipate (PBSA)), polyhydroxyalkanoates (PHA and PHB), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), starch (including modified starch), and mixtures thereof. In some such embodiments, these biodegradable polymers can provide an increased blow-up ratio when combined with cellulose acetate propionate (CAP) and / or cellulose acetate butyrate (CAB).

[0074] 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 comprises a polymer having a molecular weight of 10,000 to 1,000,000, or 50,000 to 1,000,000, or 100,000 to 1,000,000, or 250,000 to 1,000,000, or 500,000 to 1,000,000, or 600,000 to 1,000,000, or 600,000 to 1,000,000. In one embodiment or in combination with any other embodiment, the PHA can comprise polyhydroxybutyrate-co-hydroxyhexanoate.

[0075] Nucleating agent

[0076] Nucleating agent means a chemical or physical material that provides sites for the formation of cells in a molten formulated mixture (such as in a CE melt composition). As will be described in more detail below, the nucleating agent can be added to the compounded CE material during the compounding process. Alternatively or in addition, the nucleating agent can be added during the foam sheet production process. For example, the nucleating agent can be blended with the formulation in the extruder hopper introduced into the extrusion section. Alternatively, the nucleating agent can be added to the CE melt composition in the extruder itself. Nucleating agents can include physical nucleating agents and chemical nucleating agents. A physical nucleating agent is a material that is immiscible with the polymer matrix of the CE melt composition at the extrusion temperature of the extrusion section. A chemical nucleating agent is a material that reacts (e.g., decomposes) to form a physical nucleating agent during the extrusion process (e.g., at the extrusion temperature in the extruder). Therefore, a chemical nucleating agent can be considered to be (and referred to herein as) a precursor to a physical nucleating agent formed in situ.

[0077] Suitable physical nucleating agents will include fine particles of 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 will have an average particle size of less than 1000 microns, less than 500 microns, less than 100 microns, less than 50 microns, less than 25 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 2 microns, less than 1.5 microns, and / or less than 1.0 microns. However, in some other embodiments, particles having nanoscale dimensions may be preferred. Furthermore, in some embodiments, the physical nucleating agent will preferably have a high aspect ratio (i.e., width:height). For example, in some embodiments, the average aspect ratio of the physical nucleating agent will be greater than 1:1, greater than 2:1, greater than 5:1, greater than 10:1, greater than 20:1, greater than 30:1, greater than 40:1, greater than 50:1, greater than 75:1, and / or greater than 100:1. In addition, as described above, the physical nucleating agent should be immiscible with the polymer matrix of the CE melt composition at the extrusion temperature of the extrusion zone. Thus, in some embodiments, the physical nucleating agent should have a melting temperature of at least 220° C., at least 230° C., at least 240° C., at least 250° C., at least 275° C., at least 300° C., at least 325° C., or at least 350° C. However, the physical nucleating agent can be selected such that it has the ability to recrystallize upon cooling after melting.

[0078] Examples of suitable inorganic physical nucleating agents include, but are not limited to, minerals such as talc, CaCO 3 , mica, and mixtures of at least two of the foregoing. A representative example is Heritage Plastics HT6000 linear low density polyethylene (LLDPE) based talc concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon oxide, titanium oxide, magnesium oxide, aluminum oxide and calcium silicate, barium sulfate, kaolin, aluminum trihydrate ATH (Al (OH) 3 ), MDH (Mg (OH) 2 ), diatomaceous earth, magnetite / hematite, halloysite, zinc oxide and titanium dioxide. In some embodiments, the inorganic nucleating agent will comprise an oxide, such as a metal oxide or mixed metal oxide, such as an oxide selected from one or more of the following: aluminum oxide, antimony oxide, arsenic oxide, bismuth oxide, boron oxide, calcium oxide, gallium oxide, iron oxide, lithium oxide, magnesium oxide, silicon oxide and titanium oxide. In other embodiments, the inorganic nucleating agent will comprise a silicate, for example, a silicate selected from one or more of the following: magnesium silicate and calcium silicate.

[0079] It has been found that biodegradable natural granular materials (e.g., organic nucleating agents) derived from renewable organic sources are also used as effective physical nucleating agents. Natural materials that can be used as physical nucleating agents include materials made of cellulose fiber and / or cellulose starch. Examples include, but are not limited to, almond shell powder, animal fiber, apricot shell powder, bamboo powder, bark powder, clam shell powder, coconut shell powder, coconut chaff, cork powder, corn cob powder, corn cob crumbs, cotton seed shells, cotton linter and fiber, hazelnut shell powder, kenaf powder, natural fiber, nut shells and powder, oat fiber powder, olive kernel powder, peanut shell powder, pecan shell powder, pine nut shell powder, pistachio shell powder, plant fiber, rice husk powder, rice husk grains, rice husk, soy flour, starch powder (hydrophobicity), walnut shell powder, wheat bran, wheat husk and wood powder. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, stearic acid metal salts, carbon black and dolomite.

[0080] As described above, suitable chemical nucleating agents (or precursors to in-situ formed physical nucleating agents) are configured to decompose upon reaching a threshold chemical reaction temperature to create cell nucleation sites in the CE melt composition. These small cells serve as nucleation sites for larger cell growth from physical or other types of foaming agents. In some embodiments, the precursor is configured to form a gas such as CO2 or N2 during extrusion of the granular material.

[0081] Examples of chemical nucleating agents include, but are not limited to, acids such as citric acid or citric acid-based materials. Other acids may include lauric acid, stearic acid, tartaric acid, ascorbic acid, propionic acid, and caproic acid. A representative example is HYDROCEROL TMCF-40E (available from Clariant Corporation) contains citric acid and a crystal nucleating agent. In some embodiments, the chemical nucleating agent will include a combination of an acid and an alkali, such as a carbonate, which can include sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, etc. For example, a representative example of a chemical nucleating agent is a combination of citric acid and sodium bicarbonate. In some embodiments, the chemical nucleating agent can include a carrier in which the active component of the nucleating agent is dispersed. For example, another representative example of a chemical nucleating agent is a combination of citric acid, sodium bicarbonate, and a carrier. In some embodiments, the carrier can include polystyrene. However, the carrier can include other compositions, such as various biopolymers (e.g., polybutylene succinate, Capa polyester, etc.), polyolefins, acrylic copolymers (e.g., ethylene methyl acrylate), etc. In some such embodiments, citric acid and sodium bicarbonate can constitute about half (wt%) of the chemical nucleating agent, while the carrier constitutes the remaining half (wt%). In addition, in some such embodiments, the sodium bicarbonate in the chemical nucleating agent can be more than citric acid. For example, sodium bicarbonate may be about three times as present (wt %) as citric acid in a chemical nucleating agent.It should also be understood that in some embodiments, a carrier may not be needed or used, such as where the nucleating agent is Hecofoam or Hydrocerol.

[0082] In one embodiment or combination with any embodiment mentioned herein, the nucleating agent is present in an amount of 0.1 to 10 wt%, 0.1 to 5.0 wt%, at least 0.1 wt%, at least 0.25 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.25 wt%, at least 1.5 wt%, at least 1.75 wt%, at least 2.0 wt%, at least 2.25 wt%, at least 2.5 wt%, at least 2.75 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt% and / or less than 7.5 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agent used herein can comprise a combination or mixture of two or more different types of nucleating agents.

[0083] Note that, whether in the form of a compounded CE material or a CE melt composition, the cellulose ester material is generally capable of accepting a maximum amount of nucleating agent that can serve to form nucleation sites. Any remaining nucleating agent added to the cellulose ester material will be retained as a filler. Based on the type of filler used, the filler can provide various properties for the resulting cellulose ester foam and / or product. For example, some fillers can provide increased / decreased density, ductility, Young's modulus, yield strength, heat distortion temperature, permeability, impact resistance, elongation at break, adhesion characteristics, biodegradability, etc. of the cellulose ester material. Fillers can also be used to change the visual characteristics (e.g., color, opacity, etc.) and tactile characteristics (e.g., material continuity, surface roughness, etc.) of the cellulose ester material.

[0084] foaming agent

[0085] A blowing agent refers to a physical or chemical material (or combination of materials) that is used to expand the nucleation sites. The blowing agent may include a chemical blowing agent, a physical blowing agent, a combination thereof, or several types of chemical and physical blowing agents. The function of the blowing agent is to reduce the density of the material by enlarging the cells formed in the molten formulation at the nucleation sites. The blowing agent can be added to the CE melt composition in the extruder. It has been surprisingly found that the hygroscopic properties of biodegradable particulate natural fillers allow them to absorb water and carry the absorbed water into the molten resin mixture, where the water can act as a physical blowing agent.

[0086] The example of physical foaming agent comprises H2O, N2, CO2, alkane, olefin, ether, ketone, argon, helium, air or mixture.In addition, it has been surprisingly found that the hygroscopic property of biodegradable granular natural filler allows them to absorb moisture and bring the absorbed water into the molten resin mixture, wherein water can serve as physical foaming agent.Hygroscopic biodegradable natural filler can be mixed with composition and allows to absorb moisture before the foaming process, then releases water in the foaming process and serves as physical foaming agent.Beneficially, water also can be used as the plasticizer for cellulose ester resin.In addition, in some embodiments, physical foaming agent can comprise hydrocarbon, such as pentane / isopentane or butane / isobutane.Other hydrocarbons can comprise propane, ethane, methane, hexane, cyclohexane, cyclopentane, cyclobutene etc.

[0087] Chemical foaming agents are materials that degrade or react to produce gases (e.g., CO2 or N2). Such gases expand the cells in the molten resin mixture and / or the resulting foam mixture to produce a structural material having a plurality of gas voids dispersed throughout. Chemical foaming agents can be endothermic or exothermic. Chemical foaming agents typically degrade at a specific temperature to decompose and release gas. Examples of chemical foaming agents include azodicarbonamide, acids (e.g., citric acid), and carbonates such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, and the like, and combinations thereof.

[0088] In one embodiment or in combination with any of the embodiments mentioned herein, the above blowing agents can be combined with a secondary blowing agent (or co-blowing agent). In some embodiments, the co-blowing agent is selected from methyl acetate, ethanol, ketones (e.g., acetone), and mixtures thereof.

[0089] In one embodiment or in combination with any of the embodiments mentioned herein, the foaming agent (and any co-foaming agent) is present in an amount of 0.3 to 1.5 wt%, or 0.3 to 2.0 wt%, or 0.3 to 2.5 wt%, or 0.3 to 3.0 wt%, or 0.3 to 3.5 wt%, or 0.3 to 4.0 wt%, or 0.3 to 8%, or 1.3 to 1.5 wt%, or 1.3 to 2.0 wt%, or 1.3 to 2.5 wt%, or 1.3 to 3.0 wt%, or 1.3 to 3.5 wt%, or 1.3 to 4.0 wt%, or 1.3 to 4.5 wt%, or 1.3 to 5.0 wt%, or 1.3 to 5.5 wt%, or 1.5 to 3.0 wt%, or 1.5 to 4.0 wt%, or 1.5 to 5.0 wt%, or 1.5 to 6.0 wt%, or 2.0 to 3.0 wt%, or 2.0 to 4.0 wt%, or 2.0 to 5.0 wt%, or 2.0 to 6.0 wt%, or 2.5 to 3.0 wt%, or 2.5 to 4.0 wt%, or 2.5 to 5.0 wt%, or 2.5 to 6.0 wt%, or 3.0 to 4.0 wt%, or 3.0 to 5.0 wt%, or 3.0 to 6.0 wt%, or 0.0 to 9.0 wt%, or 0.5 to 9.0 wt%, or 1.0 to 9.0 wt%, or 1.5 to 9.0 wt%, or 2.0 to 9.0 wt%, or 2.5 to 9.0 wt%, or 3.0 to 9.0 wt%, or 3.5 to 9.0 wt%, or 4.0 to 9.0 wt%, or 4.5 to 9.0 wt%, or 5.0 to 9.0 wt%, or 5.5 to 9.0 wt%, or 6.0 to 9.0 wt%, or 6.5 to 9.0 wt%, or 7.0 to 9.0 wt%, or 7.5 to 9.0 wt%, or 8.0 to 9.0 wt%, or 8.5 to 9.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the foaming agent used herein can comprise a combination or mixture of two or more different types of foaming agents.

[0090] Surface modifying additive

[0091] Surface modification additives refer to materials that can be added to a cellulose ester composition to modify the structure of the composition (or the resulting foam article) and thereby improve the processing of the cellulose ester composition. For example, the inventors of the present application have discovered that adding a surface modification additive to a compounded CE material (e.g., to pellets during the compounding process) or a CE melt composition (e.g., during the extrusion process) can improve processing by reducing unwanted adhesion of the CE melt composition to a die or mandrel (or other component of the foam sheet production process). This reduction in adhesion can be achieved by the surface modification additive inhibiting the fusion of the cellulose ester caused by the plasticizer. The addition of a surface modification additive can also reduce blocking of the cellulose ester foam sheet produced in the sheet forming section. In addition, the surface modification additive can also improve the foam sheet production process by allowing the process to be carried out at a lower temperature and / or allowing an increased blow-up ratio when the melt composition is drawn across the forming mandrel.

[0092] Furthermore, in some embodiments, the surface modification additive can function as an antistatic additive that suppresses sparking or arcing in the CE melt composition. Suppressing sparking or arcing can be particularly important when hydrocarbons are used as blowing agents to reduce the chance of igniting the hydrocarbons and causing a fire. Advantageously, the surface modification additive can also reduce the outward diffusion of blowing agents such as hydrocarbons from the foam sheet or the resulting article. In some embodiments, the hydrocarbon itself can be used as a surface modification additive.

[0093] However, more general examples of surface modification additives that can be used in compounding CE materials (e.g., during compounding) or CE melt compositions (e.g., during foam sheet production) according to embodiments of the present invention include fatty acids such as palmitic acid, tallow fatty acid, stearic acid, oleic acid, linoleic acid and linolenic acid, arachidic acid / behenic acid, behenic acid, and erucic acid. Surface modification additives can also include fatty acid amides such as erucamide, oleamide, stearamide, behenamide, secondary amides, and bisamides.

[0094] The other example of surface modification additive can include glyceride and / or stearate, such as monoglyceride, diglyceride and triglyceride.Monoglyceride can include glyceryl monostearate or monoglyceride derivatives, such as diacetyl tartaric acid ester (DATEM), ethoxylated monoglyceride, succinyl monoglyceride and propylene glycol monoester (PGME) of monoglyceride and diglyceride.The example of surface modification additive can also include metal stearate, such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate and / or their combination (for example, calcium stearate / zinc stearate).The example of surface modification additive can also include wax, such as polyolefin wax (polypropylene wax and polyethylene wax), oxidized olefin wax, ethylene acrylic acid (EAA) copolymer wax, ethylene methyl acrylate (EMA) copolymer wax, EAA ionomer wax, acrylic acid wax and / or natural wax, such as rice bran wax, sunflower wax, sugarcane wax, candelilla wax, soybean wax, beeswax, candelilla wax and carnauba wax.

[0095] Other non-exclusive examples of surface modification additives include aliphatic diesters (for example, dioctyl adipate), polyglycol diesters, alkyl alkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters and alkyl monoesters. In addition, various oils can be used as surface modification additives, such as aromatic oils, naphthenic oils, glyceride oils, silicone oils and epoxidized oils (for example, soybean oil and linseed oil). Therefore, in some embodiments, surface modification additives include plasticizers, such as aliphatic diester plasticizers, polyester plasticizers etc. In addition, in some embodiments, surface modification additives can include polyhedral oligomeric silsesquioxanes (POSS).

[0096] More generally, the surface modification additives used in embodiments of the present invention can have a lower polarity than the cellulose ester in the compounded CE material (e.g., during compounding) or the CE melt composition (e.g., during foam sheet production). For example, the surface modification additive can have (based on the Hansen solubility parameter): less than 25 MPa 1 / 2 , less than 20MPa 1 / 2 , or less than 19.5MPa 1 / 2 Total solubility parameter δ; less than 18MPa 1 / 2 , less than 16MPa 1 / 2 , or less than 14MPa 1 / 2 The dispersion solubility parameter δ d Less than 12MPa 1 / 2 , less than 8MPa 1 / 2 , or less than 4MPa 1 / 2 Solubility parameter δ of the dipole intermolecular force d; and / or less than 11MPa 1 / 2 , less than 10MPa 1 / 2 , or less than 9MPa 1 / 2 The hydrogen bond solubility parameter δ h However, in some other embodiments, the surface modification additive used in embodiments of the present invention may have a higher polarity than the cellulose ester in the compounded CE material (e.g., during compounding) or the CE melt composition (e.g., during foam sheet production). For example, the surface modification additive may have (based on Hansen Solubility Parameters): greater than 21.5 MPa 1 / 2 , greater than 23MPa 1 / 2 , or greater than 25MPa 1 / 2 In some embodiments, the surface modification additive may have a boiling point greater than 200°C, greater than 220°C, greater than 240°C, greater than 260°C, greater than 280°C, or greater than 300°C. In addition, the surface modification additive may have a molecular weight greater than 100 g / mol, greater than 150 g / mol, greater than 220 g / mol, greater than 260 g / mol, greater than 300 g / mol, or greater than 340 g / mol and / or no more than 1000 g / mol, no more than 2500 g / mol, or no more than 5000 g / mol. Still further, it may be preferred that the surface modification additive is insoluble in one or more plasticizers used in the cellulose ester composition. For example, it may be preferred that the surface modification additive is insoluble in triacetin. Finally, in some embodiments, the surface modification additive may be biodegradable and / or food compliant or FDA approved.

[0097] In one embodiment or combination with any embodiment mentioned herein, the surface modification additive is present in an amount from 0.05 to 0.75 wt%, or 0.05 to 1.0 wt%, or 0.05 to 2.5 wt%, or 0.05 to 5.0 wt%, or 0.75 to 1.0 wt%, or 0.75 to 2.5 wt%, or 0.75 to 5.0 wt%, or 0.1 to 1.0 wt%, or 0.1 to 2.5 wt%, 0.1 to 5.0 wt%, or 1.0 to 2.5 wt%, or 1.0 to 5.0 wt%, or 2.5 to 5.0 wt%, all based on the total weight of the cellulose ester composition. In some embodiments, the surface modification additive used herein can comprise a combination or mixture of two or more different types of surface modification additives.

[0098] Melt strength enhancers

[0099] The elasticity of the cellulose ester composition, and particularly in heating processes such as extrusion and thermoforming processes, can be increased by adding one or more melt strength enhancers. Such melt strength enhancers can be in the form of functional ion components. Various compounds and materials can be used as long as they contain ionic functional groups. For example, in some embodiments, the functional ion component is selected from gum arabic, sulfopolyesters, quaternary ammonium salts, ionomers, ionic liquids, ionic waxes and mixtures thereof.

[0100] Products

[0101] The above-mentioned extrusion section and / or sheet forming section can be used to form an extruded sheet of cellulose ester foam. Such extruded sheet comprises a structural material with a plurality of gas voids dispersed throughout. Such gas voids are formed by the expansion of a foaming agent in the form of a gas in a cellulose polymer melt. The structural material is based on cellulose ester and has a specific amount of constituent components of the structural material (e.g., cellulose ester, plasticizer, nucleating agent, surface modification additive, etc.) that have been described in more detail above. Articles can be formed by extruded sheets of foam according to the embodiment and can be particularly used in the food service industry. Exemplary articles include meat trays. Articles can have one or more particularly advantageous properties. For example, the article can be biodegradable and / or compostable, and / or the article can have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0102] In one embodiment or combination with any of the embodiments mentioned herein, the foam has a viscosity of less than 0.20 g / cm 3 , less than 0.18g / cm 3 , less than 0.15g / cm 3 , less than 0.12g / cm 3 , less than less than 0.10g / cm 3 , less than 0.08g / cm 3 , less than less than 0.06g / cm 3 , or less than 0.04g / cm 3 , or 0.04 to 0.8 g / cm 3 , 0.04 to 0.6 g / cm 3 , 0.04 to 0.5 g / cm 3 , 0.04 to 0.4 g / cm 3 , 0.04 to 0.3 g / cm 3 , 0.04 to 0.2 g / cm 3 , 0.04 to 0.15 g / cm 3 , 0.04 to 0.12 g / cm 3 , 0.04 to 0.10 g / cm 3 , 0.04 to 0.08 g / cm3 , 0.04 to 0.06 g / cm 3 , or 0.05 to 0.8 g / cm 3 , 0.05 to 0.6 g / cm 3 , 0.05 to 0.5 g / cm 3 , 0.05 to 0.4 g / cm 3 , 0.05 to 0.3 g / cm 3 , 0.05 to 0.2 g / cm 3 , 0.05 to 0.15 g / cm 3 , 0.05 to 0.12 g / cm 3 , 0.05 to 0.10 g / cm 3 , 0.05 to 0.08 g / cm 3 , 0.06 to 0.8 g / cm 3 , 0.06 to 0.6 g / cm 3 , 0.06 to 0.5 g / cm 3 , 0.06 to 0.4 g / cm 3 , 0.06 to 0.3 g / cm 3 , 0.06 to 0.2 g / cm 3 , 0.06 to 0.15 g / cm 3 , 0.06 to 0.12 g / cm 3 , 0.06 to 0.10 g / cm 3 , 0.06 to 0.08 g / cm 3 , 0.08 to 0.8 g / cm 3 , 0.08 to 0.6 g / cm 3 , 0.08 to 0.5 g / cm 3 , 0.08 to 0.4 g / cm 3 , 0.08 to 0.3 g / cm 3 , 0.08 to 0.2 g / cm 3 , 0.08 to 0.15 g / cm 3 , 0.08 to 0.12 g / cm 3 , 0.08 to 0.10 g / cm 3 , 0.1 to 0.8 g / cm 3 , 0.1 to 0.6 g / cm 3 , 0.1 to 0.5 g / cm 3 , 0.1 to 0.4 g / cm 3 , 0.1 to 0.3 g / cm 3 , 0.1 to 0.2 g / cm 3 , 0.1 to 0.15 g / cm 3 , 0.1 to 0.12 g / cm3 , 0.2 to 0.8 g / cm 3 , 0.2 to 0.6 g / cm 3 , 0.2 to 0.5 g / cm 3 , 0.2 to 0.4 g / cm 3 , 0.2 to 0.3 g / cm 3 , 0.3 to 0.6 g / cm 3 , 0.3 to 0.5 g / cm 3 , 0.3 to 0.4 g / cm 3 , 0.4 to 0.6 g / cm 3 , 0.4 to 0.5 g / cm 3 , or 0.5 to 0.6 g / cm 3 density.

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

[0104] Further inventive concepts relate to methods and systems for producing pellets, foam sheets and / or articles.

[0105] As described above, embodiments of the present invention are methods and systems for producing biodegradable cellulose ester compositions, sheets, and articles. In particular, optimal and maximum blow-up ratios (BURs) can be achieved and / or increased, thereby maximizing the amount of usable foam sheet material that can be produced during the sheet forming process. The optimal or maximum BUR can be increased by including certain polymers and / or additives that adjust the elasticity, melt strength, and / or glass transition temperature (Tg) of the composition and / or by maintaining the composition at an optimal temperature to increase elasticity.

[0106] The embodiments described herein are particularly useful in producing cellulose ester foam sheets and articles, although the embodiments may also be used in other sheet and article production applications.

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

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

[0109] In one embodiment or combination with any embodiment mentioned herein, the foam or article exhibits greater than 90% disintegration after 12 weeks according to the Disintegration Test Protocol as described in the specification.

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

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

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

[0113] Definitions

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

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

[0116] As used herein, the terms“comprising,”“comprises” and“comprise,” are open-ended transitional phrases used to transition from a preceding clause to one or more elements listed in the clause that follows each respective transitional phrase. The one or more elements listed after each respective transitional phrase are not necessarily exhaustive of a subject of the clause in which the transitional phrase is used.

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

[0118] As used herein, the term“biodegradable” generally refers to the biological conversion and consumption of organic molecules. Biodegradability is an inherent property of the material itself, and materials can exhibit different degrees of biodegradability depending on the specific conditions to which they are exposed. The term“disintegrable” refers to the tendency of a material to physically break down into smaller pieces when exposed to specific conditions. The degree of disintegration depends on the material itself as well as the physical size and configuration of the article being tested. Ecotoxicity measures the impact of a material on plant life, and the heavy metal content of a material is determined according to procedures specified in standard test methods.

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

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

[0121] according to To be considered "biodegradable" under soil composting conditions, materials must demonstrate a total biodegradation of at least 90% (e.g., compared to the initial sample) or a biodegradation of at least 90% of the maximum degradation of a suitable reference material after both the reference and test articles have reached a plateau. The maximum test duration for biodegradability under soil composting conditions is 2 years.

[0122] As used herein, the term "blow-up ratio" means the ratio of the inner diameter of the extruder die to the outer diameter of the outer mandrel.

[0123] The claims are not limited to the disclosed embodiments

[0124] The preferred forms of the present invention described above are intended to be illustrative only and should not be used in a limiting sense to interpret the scope of the present invention. Those skilled in the art may easily modify the exemplary embodiments set forth above without departing from the spirit of the present invention.

[0125] The inventors hereby declare that they intend to determine and assess the reasonable and fair scope of the invention under the doctrine of equivalents as it relates to any device that does not materially depart from the literal scope of the invention as set forth in the following claims.

[0126] Experimental part

[0127] abbreviation

[0128] BUR is blow ratio; wt% is weight percentage; BA is blowing agent;

[0129] Foam sheet samples were produced on a tandem foam production line manufactured by Krauss Maffei. The extrusion line consisted of a ZE30 twin-screw extruder (as the primary extruder) and a KE60 single-screw extruder (as the secondary cooling extruder). The formulation additives were added to the KE30 twin-screw feeder using a loss and weight feeder. The physical foaming agent was injected into the barrel of the primary extruder at approximately 1 The material is extruded from a 50 mm annular die and conveyed onto a sizing mandrel. The annular film is then slit and converted into a flat film in the tensioning / winding station section of the roller.

[0130] The material composition is cellulose acetate resin with 15 to 20 wt% of processing aids and stabilizers. The material is injected with n-pentane as a blowing agent. Additional additives to the process include 1 wt% of ABT 1000 talc and 1% of a chemical blowing agent. The material is extruded between 200°C and 220°C in the primary extruder and 170°C to 190°C in the secondary extruder. The line output rate is 40 kg / h.

[0131] Blow-up ratio and lay-flat width are important terms for foams. The blow-up ratio (BUR) is defined as the diameter of the sizing mandrel or calibration piece divided by the diameter of the die. The lay-flat width is the mandrel diameter multiplied by the constant PI (3.14159).

[0132] Blow-up ratio: BUR = mandrel diameter / die diameter

[0133] Table 1.

[0134]

[0135] The application has certain stiffness requirements, which are mainly controlled by the resin modulus and the thickness of the part. The following table shows some common material thicknesses used in commercial applications today.

[0136] Table 2.

[0137] application thickness Small meat tray 4 to 6 mm Large meat tray 5 to 7 mm Clamshell items 2 to 4 mm Buffet Tray 3 to 6 mm Egg cartons 2 to 4 mm plate 2 to 4 mm bowl 2 to 4 mm

[0138] Achieving the ideal target foam thickness is complex. Like other extrusion methods, it is related to output rate and take-off speed; however, it is also affected by mandrel sizing and foam efficiency. Foam behavior is also affected by many variables, including the type and level of physical blowing agents, the type and level of chemical blowing agents, the type and level of nucleating agents, temperature, and pressure.

[0139] Table 3 shows how the level of physical blowing agent can affect foam thickness at a BUR of 3.2. By further optimizing the process, thicknesses as high as 5 mm are possible. At a BUR of 2.8 (as shown in Table 2), even greater thicknesses, up to nearly 7 mm, can be achieved by varying the level of physical blowing agent.

[0140] Table 3. Effect of blowing agent level on maximum average thickness at a BUR of 3.2.

[0141]

[0142] Table 4. Effect of blowing agent level on maximum average thickness at a BUR of 2.8.

[0143]

[0144] Table 5. Effect of BUR on maximum thickness

[0145]

[0146] The line rate ratio is defined as:

[0147] Output rate (kg / min) / Linear speed (M / min) = Linear speed ratio Kg / M

[0148] Line speed is the speed at which the pull roller assembly that winds the foam into a roll operates. As the extruder size increases from small (20-40 kg / h) to large (500-1000 kg / h), the line speed ratio allows for product scalability.

[0149] Table 6.

[0150]

Claims

1. A method for forming a foam sheet, the method comprising: (a) extruding a composition comprising a cellulose ester through an annular die having an inner die diameter (X) to form a tubular extrudate; as well as (b) pulling the tubular extrudate over a forming mandrel having an outer diameter of 2.1X to 3.9X the mandrel.

2. The method of forming a foam sheet according to claim 1, further comprising processing the tubular extrudate to form a foam sheet.

3. The method for forming a foam sheet according to claim 2, wherein the foam sheet has a viscosity of 0.05 to 0.12 g / cm 3 density.

4. The foam sheet forming method of any one of claims 1 to 3, wherein the composition comprises 2.0 to 5 wt% of one or more physical blowing agents.

5. The foam sheet forming method according to any one of claims 1 to 4, wherein the line speed ratio is 0.10 to 0.33 kg / m.

6. The foam sheet forming method according to any one of claims 2 to 5, wherein the foam sheet has a thickness of 2 to 7 mm, and the mandrel outer diameter is 2.5X to 3.6X.

7. The foam sheet forming method according to any one of claims 1 to 6, wherein the line speed ratio is 0.1 to 0.28 kg / m.

8. The foam sheet forming method according to claims 2-4, wherein the foam sheet has a thickness of 4 to 7 mm, and the mandrel outer diameter is 2.5X to 3.3X.

9. The foam sheet forming method according to any one of claims 2 to 4 or 8, wherein the line speed ratio is 0.19 to 0.33 kg / m.

10. The foam sheet forming method according to any one of claims 2 to 4, wherein the foam sheet has a thickness of 2 to 4 mm, and the mandrel outer diameter is 3.0X to 3.9X.

11. The foam sheet forming method according to any one of claims 1 to 4 or 10, wherein the line speed ratio is 0.1 to 0.22 kg / m.

12. The foam sheet forming method of any one of claims 1-11, wherein the extrudate or foam sheet has fewer than 5, or fewer than 4, or fewer than 3, or fewer than 2, or no corrugations.

13. The foam sheet forming method of any one of claims 1 to 12, wherein the composition has a glass transition temperature (Tg), and the composition is extruded (a) through the annular die at a temperature at least 40°C higher than the Tg of the composition.

14. The foam sheet forming method of claim 13, wherein the composition is extruded (a) at a temperature of at least 160°C.

15. The foam sheet forming method of any one of claims 1-14, wherein the forming mandrel has an outer surface temperature greater than 30°C.

16. The method of forming a foam sheet according to any one of claims 1 to 15, wherein the composition comprises from 1 wt% to 50 wt% of one or more polymers and / or one or more additives effective to increase the elasticity and / or melt strength of the composition, based on the total weight of the composition.

17. The foam sheet forming method of claim 16, wherein the one or more polymers have a glass transition temperature (Tg) below room temperature.

18. The foam sheet forming method of claim 17, wherein the one or more additives are effective to lower the Tg of the composition.

19. The foam sheet forming method according to any one of claims 16 or 18, wherein the one or more additives include chemical blowing agents, physical blowing agents, co-blowing agents, surface modification additives, elastomeric polymers, and melt strength enhancers.

20. The foam sheet forming method of claim 19, wherein the one or more additives include a functional ionic component as the melt strength enhancer.

21. The method of forming a foam sheet according to claim 20, wherein the functional ionic component is selected from the group consisting of gum arabic, sulfopolyester, quaternary ammonium salt, ionomer, ionic liquid, ionic wax and mixtures thereof.

22. The method of forming a foam sheet according to any one of claims 1 to 21, wherein the composition comprises a blend comprising cellulose acetate and a biodegradable polymer selected from the group consisting of polyethylene succinate (PES), poly(glycolic acid) (PGA), starch, and mixtures thereof.

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