Blow-up ratio in foam sheet manufacturing process

Abstract

Compositions, systems, and methods for use in the manufacturing process of foamed sheets. Such processes generally involve extruding a composition and stretching the extruded material on a molding mandrel. The ratio of the diameter of the molding mandrel to the diameter of the extruder die is called the "blow-up ratio" (BUR). The compositions, systems, and methods according to the embodiments relate to blow-up ratios in the manufacture of cellulose ester foamed sheets, with the aim of providing maximum sheet yield without rupturing the extruded material.

Description

Background Art

[0001] Many foamed products, such as food packaging supplies, are intended to be disposable items that are discarded after use. One commercially important material used to make foamed products is polystyrene. However, polystyrene cannot be composted or biodegraded. Furthermore, some municipalities, states, and countries have implemented or are considering implementing bans on the use of polystyrene foams. Therefore, it is desirable to find alternative materials for use in foamed products, as well as promising compositions, methods, and systems for manufacturing such products.

[0002] During the manufacturing process of a foamed sheet, the extruded composition is generally stretched over a forming mandrel. In conventional processes using polystyrene, the blow-up ratio (i.e., the ratio of the diameter of the forming mandrel to the diameter of the extruder die) can range from 4 to 5. However, for different compositions (such as cellulose ester compositions), the acceptable blow-up ratio may vary in order to avoid rupture of the material. Therefore, it is desirable to find the acceptable blow-up ratio for cellulose ester compositions and to find compositions and processes for improving the production yield of foamed sheet materials by increasing the blow-up ratio of cellulose ester compositions.

Summary of the Invention

[0003] In one embodiment, or in combination with any other embodiment referred to herein, a foamed sheet forming process is provided. The process includes (a) extruding a composition comprising a cellulose ester through an annular die having a die inner diameter (X) so as to form a tubular extrudate, and (b) stretching the tubular extrudate over a forming mandrel having a mandrel outer diameter of 2.1X to 3.9X.

[0004] In one embodiment, or in combination with any other embodiment referred to herein, a foam sheet molding process is provided. This process comprises (a) extruding a composition comprising a cellulose ester through an annular die having an inner die diameter (X) to form a tubular extruder, and (b) stretching the tubular extruder on a molding mandrel having an outer mandrel diameter of at least 3.3X.

[0005] In one embodiment, or in combination with any other embodiment referenced herein, a foam sheet molding process is provided. This process comprises (a) extruding a composition through an annular die having an inner die diameter (X) to form a tubular extruder, and (b) stretching the tubular extruder on a tapered molding mandrel having a first end having a first diameter (Y) proximal to the annular die and a second end having a second diameter distal to the annular die, wherein the second diameter (Y) is at least 3.3X and the first diameter (Y) is smaller than the second diameter. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic diagram showing a biodegradable product molding process according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing another biodegradable product molding process according to an embodiment of the present invention. [Figure 3] This is a schematic diagram showing an extrusion section that can be used in the article molding process of Figure 1 and / or Figure 2 according to an embodiment of the present invention. [Figure 4] This is a schematic diagram showing another extrusion section that can be used in the article molding process of Figures 1 and 2 according to embodiments of the present invention. [Figure 5] This is a schematic diagram showing a sheet molding section that can be used in the article molding process of Figure 1 and / or Figure 2 according to embodiments of the present invention. [Figure 6] This is a schematic diagram showing an exemplary molded mandrel, including a heat conduction tube adjacent to the surface of the mandrel, according to an embodiment of the present invention. [Modes for carrying out the invention]

[0007] The embodiments generally relate to methods, systems, and compositions for forming biodegradable particulate materials (e.g., pellets), foamed sheets, and articles. In certain embodiments, the methods, systems, and compositions described herein provide an acceptable and optimal blow-up ratio when stretching a cellulose ester molten composition on a molding mandrel in a foamed sheet molding process. In some of the same or other embodiments, the blow-up ratio can be increased, for example, by methods and synthetic additives that increase the elastic and / or melt strength of the molten composition. Figures 1 to 6 show exemplary processes including methods, systems, and compositions, which are described in further detail below.

[0008] Methods and Systems As shown in Figures 1 and 2, raw materials are introduced into a biodegradable polymer manufacturing process for producing biodegradable polymer materials. In one embodiment, or in combination with any other embodiment referred to herein, the biodegradable polymer material comprises one or more cellulose esters. The one or more cellulose esters may include cellulose acetate. In such embodiments, the raw materials may include pulp such as wood pulp and / or cotton pulp. The pulp may be dissolvable grade pulp and / or paper grade pulp. The cellulose in the pulp can be esterified, for example with acetic acid, to form biodegradable cellulose ester polymers such as cellulose acetate polymers.

[0009] Next, the biodegradable polymer material can be introduced into a compounding process. In this process, the biodegradable polymer material can be mixed with a plasticizer and optionally one or more other additives (e.g., stabilizers) to form a compounding material containing a plasticized biodegradable polymer. Other additives may also be mixed with the polymer and plasticizer. For example, as shown in Figure 2, other materials (additives) may include, but are not limited to, stabilizers, physical blowing agents (multiple), chemical blowing agents (multiple) (and / or precursors), nucleating agents (multiple), surface modifying additives (multiple), pigments (multiple), fillers (multiple), and / or other additives (multiple). Other additives may include, for example, surface modifying additives (e.g., slip agents) and / or functional ionic components. In one embodiment, or in combination with any other embodiment referred to herein, the biodegradable polymer may be mixed with one or more components having a glass transition temperature (Tg) below room temperature (about 20°C). Furthermore, or alternatively, the biodegradable polymer may contain one or more other polymers and / or additives that can increase the elastic and / or melt strength of the composition and / or decrease the Tg of the composition. Further details regarding polymers and additives that may be included in the composition are provided below. Mixing can be achieved by any known mixing technique, including but not limited to rolling in a cylindrical vessel, overhead stirring, sigma blade mixing, and tumbling.

[0010] The compounding process may include a particle formation process. The particle formation process may generally include mixing biodegradable polymer materials, plasticizers, and other additives to form a mixed composition, and forming particulate material from that composition. Specifically, the particle formation process may include a pelletizing process, and the particulate material may contain a number of pellets. The term “compounded CE material” means a cellulose ester material formed during the compounding process, which may include a mixture of cellulose esters, plasticizers, and other additives. Furthermore, such compounded CE material may take the form of particulate material or pellets. It should be understood that, as used herein, the terms “particle formation” or “particle formation process” may be the same as, or at least include, “pellet formation” or “pellet formation process.” In some embodiments, the particle formation process may include pelletizing in a water tank, pelletizing on an air-cooled belt, water pelletizing, solvent compounding, and the like.

[0011] In one embodiment, or in combination with any other embodiment referenced herein, plasticizers and other additives(s) may be mixed with cellulose esters by conventional melt compounding techniques. This technique involves mixing the cellulose esters with plasticizers and optionally other additives at appropriate temperatures and pressures in a twin-screw extruder equipped with appropriate mixing elements, to obtain a molten, uniformly combined cellulose ester mixture by the time the material is discharged from the extruder. The molten, compounded cellulose ester mixture may then be extruded through a die having an orifice approximately 2–6 mm in diameter to extrude strands. These strands may then be cooled with water (e.g., via underwater pelletizing) or air and cut at regular intervals to obtain uniform, desirable sizes and shapes called “pellets” or “granules.” While this specification describes a process for forming pelletized compounding materials, it will be understood that the compounding materials supplied to the foam sheet manufacturing process may be in any physical form (e.g., pellets, powders, granules, fibers) according to some embodiments. The term "compounded CE material" refers to a cellulose ester material formed during the compounding process, which may include a mixture of cellulose esters, plasticizers, and other additives. Furthermore, such compounded CE material may take the form of a molten mixture or particulate material (e.g., pellets, powders, granules, fibers, etc.).

[0012] Next, as described above, formulated CE materials containing pellets of plasticizable biodegradable polymers can be introduced into a foamed sheet manufacturing process, as shown in Figures 1 and 2. The foamed sheet manufacturing process may include one or more zones / steps for producing a foamed sheet or film, which will be described in more detail below. While exemplary foamed sheet manufacturing processes are described herein, it should be understood that certain embodiments described herein may also be applicable to rigid (i.e., non-foamed) materials and articles. As shown in Figure 1, various additives can be introduced into one or more zones of the foamed sheet manufacturing process in one embodiment or in combination with any other embodiments referred to herein. Additives may include, but are not limited to, stabilizers, physical foaming agents (or more), chemical foaming agents (or more) (and / or precursors), nucleating agents (or more), surface modifying additives (or more), pigments (or more), fillers (or more), and / or other additives (or more).

[0013] A foamed sheet manufacturing process may generally include an extrusion section and a sheet forming section. An exemplary extrusion section is shown in Figure 3. As shown, the extrusion section may include a feed preparation zone where solid additives may be combined with the compounded CE material and introduced into the downstream extrusion zone. In one embodiment, or in combination with any other embodiment referred to herein, the feed preparation zone may include a feed hopper. Thus, the compounded CE material and other solid additives may be deposited in the feed hopper, which directs the combined feed composition towards the extrusion zone. The feed preparation zone may further include a mixer where the compounded CE material and one or more additives may be mixed before being introduced into the hopper. Mixing can be achieved by any known mixing technique, including but not limited to rolling in a cylindrical vessel, overhead stirring, sigma blade mixing, and tumbling. Examples of solid additives that can be combined with the formulation materials include chemical blowing agents, nucleating agents, surface modifying additives, pigments, fillers, and / or other additives.

[0014] Next, the combined feed composition from the feed preparation zone may be introduced into the extrusion zone. The extrusion zone may generally include one or more extruders, which may include single-screw and / or twin-screw extruders. Within the extruder(s), the feed composition may be introduced into the extruder barrel and conveyed by a screw(s) through a die that forms an extruder from the feed composition. As the composition is conveyed through the extruder barrel toward the die, it may be heated and at least partially melted. Thus, the term “CE molten composition” is used herein to mean a cellulose ester-based feed composition melted into a fluid molten resin through the extrusion section. Heating may be supplied by an external heater positioned along the outside of the extruder barrel. The shape of the extruder is generally determined by the shape and size of the die head. The extruder may be further shaped by downstream processes as described below.

[0015] One or more additives can be introduced into the CE molten composition while it is in the extruder. For example, one or more physical blowing agents can be added to the CE molten composition by injecting them into the composition being transported in the extruder barrel.

[0016] As shown in Figure 4, in one embodiment, or in combination with any other embodiment referred to herein, the extrusion zone may include a primary extrusion vessel and a cooling vessel. The primary extrusion vessel and the cooling vessel may be separate devices or may be combined as an integrated device. In any case, the supply composition from the supply preparation zone is introduced into the primary extrusion vessel and, as it is transported through the extruder barrel as described above, is at least partially melted, thereby producing a molten CE composition. The molten CE composition exiting the primary extrusion vessel may have a temperature of about 220°C to about 240°C. One or more additives, such as blowing agents, may be added to the molten CE composition as it is transported through the primary extrusion vessel.

[0017] Next, the molten CE composition from the primary extrusion vessel is introduced into a cooling vessel. The cooling vessel may be a secondary extrusion vessel, which operates similarly to the primary extrusion vessel but at a lower temperature. In the cooling vessel, the molten CE composition can be further mixed to provide a substantially homogeneous mixture of the molten polymer and other additives(s). The molten CE composition can then be passed through a die and discharged from the die head to obtain a cellulose ester-based extruder, which can be further processed in the sheet forming section of a foamed sheet manufacturing process. In one embodiment, or in combination with any other embodiment referred to herein, the molten CE composition exiting the die head may 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.

[0018] As shown in Figure 4, one or more filtration devices may be installed within the extrusion section to filter and remove particulate matter from the molten CE composition. For example, screen changer filtration devices may be installed downstream of the primary and secondary extrusion vessels, thereby removing solid components from the molten CE composition before it passes through the die head to the sheet forming section.

[0019] The sheet forming section may include any of a variety of systems and processes for forming extruded sheets from cellulose ester material that can be used for article forming. The shape of the extruded sheet is generally determined by the shape of the die head, but the shape of the sheet formed in the sheet forming section may be determined by the shape of the die head and other downstream processes. For example, the extruded sheet may generally have a flat shape, or it may be annular and subject to further processing to form a flat sheet. In embodiments where the die is annular, the die may have diameters of 1 to 40 cm, 2 to 20 cm, 2 to 10 cm, and / or 3 to 8 cm. Furthermore, the thickness of the opening from which the extruded sheet is discharged, referred to herein as the “die gap,” may generally be 0.1 to 6.0 mm, 0.1 to 3.0 mm, and / or 0.1 to 1.0 mm in size.

[0020] An exemplary sheet forming section is shown in Figure 5. As illustrated, the CE molten composition is extruded through an annular die and stretched on a forming mandrel. A cooling fluid (e.g., air) can be flowed inside and / or outside the extruded material to cool it as it passes over the mandrel. For example, the cooling fluid can be blown from the mandrel towards the die to cool the inner surface of the extruded material between the die and the mandrel. Additionally or alternatively, the cooling fluid can be flowed across the mandrel to cool the outer surface of the extruded material as it passes over the mandrel. In some embodiments, tubular extruded materials are cooled by a cooling ring positioned around the mandrel. In certain embodiments, the cooling ring is positioned at least 1 foot, at least 2 feet, or at least 3 feet away from the annular die. As shown in Figure 6, a heated gas (steam) flow (e.g., air) can be supplied into the mandrel to ensure that the extruded material is stretched continuously on the mandrel, for example, to ensure that the extruded material remains fully expanded. In some embodiments, the heated steam stream may contain air, nitrogen, or carbon dioxide, but other gaseous components may also be used.

[0021] Temperature control of the extruder stretched on the mandrel can have a significant impact on the size limitations of the extruder and the properties of the resulting foam. In one embodiment, or in combination with any other embodiment referred to herein, the temperature of the extruded material may be maintained at a temperature higher than the glass transition temperature of the extruded material in the region between the extruder die and the mandrel. In some embodiments, the CE molten composition has a glass transition temperature (Tg) and is extruded through the annular die at a temperature 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 molten composition. In some embodiments, a heated vapor stream may 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 vapor 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 may be used to add moisture to the extruder, as the water vapor in the gas stream comes into contact with the extruder as it exits the die and is stretched on the forming mandrel.

[0022] In one embodiment, or in combination with any other embodiment referenced herein, the extruded material is stretched on the outer surface of a forming mandrel maintained at a temperature above 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 supplying heat from one or more electrically heated elements positioned at least partially adjacent to the surface. For example, one or more heating elements and / or one or more insulating elements may be positioned at least partially around the space between the annular die and / or the forming mandrel. In some embodiments, one or more heating elements include infrared (IR) heaters. Additionally or alternatively, the temperature may be controlled by flowing a heat transfer medium (heat transfer fluid) through conduits positioned at least partially adjacent to the surface to provide indirect heat transfer between the heat transfer medium and the surface.

[0023] Figure 6 shows an exemplary molded mandrel including heat conduction tubes adjacent to the mandrel surface. During operation, a heat transfer medium can be introduced into the conduits and flow through the conduits surrounding the inside of the mandrel surface. The temperature of the heat transfer medium introduced into the conduits can be adjusted as needed to maintain a desired surface temperature of the mandrel. Exemplary heat transfer fluids may include air, water, oil, glycol, and mixtures thereof, but it will be understood that other suitable heat transfer fluids may also be used.

[0024] The composition and temperature of the extruded material can affect the blow-up ratio (BUR) of the extruded material stretched on a molding mandrel. 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. In one embodiment, or in combination with any other embodiment referred to herein, the extruded material is stretched on a molding mandrel with blow-up ratios of 2.0–4.0, 2.1–3.9, 2.2–3.8, 2.3–3.7, 2.4–3.6, and 2.5–3.5, although in some embodiments, even higher blow-up ratios can be achieved. Thus, in some embodiments, the annular die has an inner die diameter (X), and the extruded material is stretched on a molding mandrel having an outer mandrel 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 extruded material is stretched on a forming mandrel having an 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 4.0X or less, 3.9X or less, 3.8X or less, 3.7X or less, 3.6X or less, or 2.5X or less.

[0025] Certain cellulose esters (or more) and other polymers and / or additives in the CE melt composition can affect the maximum BUR without causing the extruded material to burst. This limit may be influenced by the elongation ratio and / or melt strength inherent to the composition. In some embodiments, the CE composition comprises cellulose acetate, and in some embodiments, the cellulose acetate may have an optimal BUR of 2.1 to 3.9. In some embodiments, one or more polymers that are miscible or dispersible with the cellulose acetate may be included to increase the maximum BUR of the material. In some such embodiments, this miscible or dispersible polymer is selected from polyethylene succinate (PES), poly(glycolic acid) (PGA), and starch (including modified starch). In some embodiments, the CE composition may include biodegradable aliphatic polyesters and mixed esters that enable even higher BUR without causing the extruded material to burst. For example, a CE composition containing cellulose acetate propionate (CAP), polylactic acid (PLA), and / or polybutylene succinic acid (PBS) may achieve a BUR of 4.0 or higher. Other polymer blends may also achieve similar BURs. Other additives may be included that may increase the maximum BUR of the CE composition, such as chemical blowing agents, physical blowing agents, co-blowing agents, surface modifiers, elastic polymers (e.g., PEG), and melt strength enhancers (e.g., ionic functional components). Polymers and additives in CE compositions are described in more detail below.

[0026] In one embodiment, or in combination with any other embodiment referenced herein, the forming mandrel is tapered such that a first end proximal to the annular die has a first diameter and a second end distal to the annular die has a second diameter. In some embodiments, the first diameter is smaller than the second diameter, and as a result, the extruder expands to a higher BUR as it is stretched on the forming mandrel from the first end to the second end. 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–3.0Y, 1.2Y–2.8Y, 1.3Y–2.6Y, 1.4Y–2.4Y, 1.5Y–2.2Y, or 1.6Y–2.0Y. The specific ratio of the diameters of the tapered mandrel may depend on various factors such as the length of the mandrel and the composition of the extruded material. 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 of the diameter of the second end to the inner die diameter (X)). 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, or 2.3X to 3.7X.

[0027] The length of the molding mandrel generally depends on the elasticity of the extruded material, which in turn depends on several factors, including composition and temperature, as described herein. In particular, the selected blowing agent(s) can significantly affect the appropriate length of the molding mandrel. For example, a composition containing CO2 as a blowing agent may require a shorter molding mandrel than a composition containing a larger amount of hydrocarbon blowing agent. While not bound by any theory, it is believed that the internal pressure from the blowing agent prevents the extruded material from shrinking laterally. Since CO2 diffuses from the extruded material faster than hydrocarbons (e.g., pentane), the extruded material will solidify (shrink) when stretched on a longer mandrel. In one embodiment, or in combination with any other embodiment referred to herein, the molding mandrel may have lengths of 2 to 30 feet, 3 to 20 feet, 4 to 15 feet, or 5 to 10 feet. In some embodiments, particularly when CO2 is included as a blowing agent, the molding mandrel may have lengths of 2 to 5 feet.

[0028] The molded mandrel may be made of various materials, and its components may be made of the same or different materials. However, the material(s) used on the outer surface of the molded mandrel (i.e., the surface on which the extruder is stretched) can have a significant impact on the process. For example, the surface material(s) may be selected to avoid corrosion, pitting, etching, etc., by certain components in the extruded composition, such as acids (e.g., acetic acid), to provide desired heat transfer properties, and / or to have a desirable coefficient of friction with the extruded composition. In some embodiments, the surface may include aluminum and / or stainless steel. In some embodiments, the surface may include a protective coating. Exemplary protective coatings may include carbon coatings, Teflon coatings, and chromium coatings. In particular, chromium coatings have traditionally been avoided on molded mandrels due to their reaction with styrene in conventional foamed sheet compositions. However, since the compositions described herein are generally cellulose ester compositions (rather than polystyrene), such reactions are not a problem. Furthermore, or alternatively, materials and coatings that provide an overall smooth surface (as opposed to a matte surface) may be preferred, allowing the extruded material to be stretched more easily on the mandrel without bursting.

[0029] Referring again to Figure 5, a slicer (or cutting device) can be used to open up a tubular extruder, which allows the tubular shape to be formed into a flat sheet. For example, a tubular extruder passing over a mandrel may be cut open and pulled to a tension station containing one or more rollers. These rollers flatten the extruder and maintain the amount of tension required to keep the extruder pulled over the mandrel. The flattened extruder is generally in the form of a sheet, which may then be directed to a winding station, where the material may be wound for packaging and transport.

[0030] Referring again to Figures 1 and 2, the sheets produced by the sheet manufacturing process can be used to form foamed products. Foamed products will be described in more detail below. Such articles are particularly useful in the food service industry. An exemplary article is a meat tray. This article may have one or more particularly advantageous properties. For example, the article may be biodegradable and / or compostable, and / or may have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0031] In one embodiment, or in combination with any other embodiment referenced herein, the line rate ratio is 0.1-0.33 kg / m, or 0.1-0.3 kg / m, or 0.1-0.29 kg / m, or 0.1-0.28 kg / m, or 0.1-0.27 kg / m, or 0.1-0.25 kg / m, or 0.1-0.23 kg / m, or 0.1-0.22 kg / m, or 0.1-0.21 kg / m, or 0.1-0.19 kg / m, or 0.1-0.17 kg / m, or 0.1-0.15 kg / m, or 0.1-0.14 kg / m, or 0.12~0.33 kg / m, or 0.12~0.3 kg / m, or 0.12~0.29 kg / m, or 0.12~0.28 kg / m, or 0.12~0.27 kg / m, or 0.12~0.25 kg / m, or 0.12~0.23 kg / m, or 0.12~0.21 kg / m, or 0.12~0.19 kg / m, or 0.12~0.17 kg / m, or 0.12~0.15 kg / m, or 0.12~0.14 kg / m, or 0.14~0.33 kg / m, or 0.14~0.3 kg / m, or 0.14~0 0.29 kg / m, or 0.14~0.28 kg / m, or 0.14~0.27 kg / m, or 0.14~0.25 kg / m, or 0.14~0.23 kg / m, or 0.14~0.21 kg / m, or 0.14~0.19 kg / m, or 0.14~0.17 kg / m, 0.16~0.33 kg / m, or 0.16~0.3 kg / m, or 0.16~0.29 kg / m, or 0.16~0.28 kg / m, or 0.16~0.27 kg / m, or 0.16~0.25 kg / m, or 0.16~0.23 kg / m, or 0.16 ~0.21kg / m, or 0.16~0.19kg / m, 0.18~0.33kg / m, or 0.18~0.3kg / m, or 0.18~0.29kg / m, or 0.18~0.28kg / m, or 0.18~0.27kg / m, or 0.18~0.25kg / m, or 0.18~0.23kg / m, or 0.18~0.21kg / m, 0.19~0.33kg / m, or 0.19~0.3kg / m, or 0.19~0.29kg / m, or 0.19~0.28kg / m, or 0.19~0.27kg / m, or 0.19~0.The density is 25 kg / m, or 0.19–0.23 kg / m.

[0032] composition The process described above may include the preparation and extrusion of compositions that can be used in downstream processing to form useful articles. For example, in one embodiment, or in combination with any other embodiment referred to herein, the extrusion feed material may include particulate material comprising a biodegradable polymer and optionally one or more additives, such as those described herein. In one embodiment, or in combination with any other embodiment referred to herein, the feed material may provide a mixed composition comprising a biodegradable polymer and one or more additives, such as those described herein. In one embodiment, or in combination with any other embodiment referred to herein, the biodegradable polymer comprises a cellulose ester.

[0033] In one embodiment, or in combination with any other embodiments referenced herein, a cellulose ester composition comprises one or more polymers and / or other additives that function to enhance the melt strength of the composition and / or increase the elasticity of the composition. Such polymers and other additives may enable a molten composition stretched on a molding mandrel to increase the blow-up ratio without causing the extruder to burst, compared to a composition that does not contain these polymers and / or additives. For example, in some embodiments, the composition comprises one or more such polymers and / or other additives in an amount of 1% to 50% by weight, or 2% to 20% by weight. In some embodiments, the composition comprises at least one additive having a specific heat capacity of at least 1800 J / kg-C, or at least 2000 J / kg-C. In some embodiments, the composition comprises one or more additives selected from chemical blowing agents, physical blowing agents (e.g., hydrocarbon blowing agents), surface modifying additives (e.g., slip agents), biodegradable polymers (such as polyethylene glycol (PEG) and others described herein), and / or melt strength improvers (such as functional ionic components).

[0034] Further details of the composition components, including biodegradable polymers (e.g., cellulose esters) and other additives, are shown below.

[0035] Cellulose ester The cellulose esters used as described herein may be any known in the art. Cellulose esters that can be used in the embodiments herein generally contain repeating units of the following structure: [ka] In the formula, R1, R2, and R3 are independently selected from the group consisting of hydrogen, acetyl, propyl, or butyl. The substitution level of a cellulose ester is usually expressed in terms of the degree of substitution ("DS"), which is the average number of non-OH substituents per anhydrous glucose unit ("AGU"). Generally, conventional cellulose contains three hydroxyl groups in each substitutable AGU unit. Therefore, DS can have values ​​from 0 to 3. Natural cellulose is a large polysaccharide with a degree of polymerization of 250 to 5,000 even after pulping and purification, and therefore the assumption that the maximum DS is 3.0 is approximately correct. Since DS is a statistical mean, a value of 1 does not guarantee that all AGUs have one substituent. In some cases, unsubstituted anhydrous glucose may exist, some having two substituents, some three, and the value is usually a non-integer. Total DS is defined as the average number of substituents in total per anhydrous glucose unit. The degree of substitution per AGU can also mean specific substituents, such as hydroxyl or acetyl, for example. In one embodiment, or in combination with any other embodiment, n is an integer in the range of 25 to 250, or 25 to 200, or 25 to 150, or 25 to 100, or 25 to 75.

[0036] In one embodiment, or in combination with any other embodiment, a cellulose ester may have at least two anhydrous glucose rings and at least 50 to a maximum of 5,000 anhydrous glucose rings, or at least 50 to less than 150 anhydrous glucose rings. The number of anhydrous glucose 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, a cellulose ester may have an intrinsic viscosity (IV) of about 0.2 to about 3.0 deciliters / gram, or about 0.5 to about 1.8, or about 1 to about 1.5, measured at a temperature of 25°C for 0.25 grams of sample in 100 ml of a 60 / 40 wt solution of phenol / tetrachloroethane. In one embodiment, or in combination with any other embodiment, cellulose esters useful herein may have a DS / AGU of about 1 to about 3.0, or about 2.0 to about 2.9, or about 2.2 to about 2.8, or 1 to less than 2.2, or 1 to less than 1.5, where the substituted ester is acetyl.

[0037] Cellulose esters can be produced by any method known in the art. An example of a cellulose ester production process is taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th Edition, Vol. 5, Wiley-Interscience, New York (2004), pp. 394-444. Cellulose, the starting material for producing cellulose esters, can be obtained from a variety of grades and sources, including, among others, cotton linters, softwood pulp, hardwood pulp, corn fiber, and other agricultural sources, as well as bacterial cellulose.

[0038] One method for producing cellulose esters involves esterification of cellulose by mixing it with a suitable organic acid, acid anhydride, and catalyst. The cellulose is then converted to cellulose triester. Next, the cellulose triester can be hydrolyzed by adding a water-acid mixture, and then filtered to remove gel particles or fibers. Water is then added to the mixture to precipitate the cellulose ester. The cellulose ester may then be washed with water to remove reaction by-products, followed by dehydration and drying.

[0039] The hydrolyzed cellulose triesters may have three acetyl substituents. These cellulose esters can be prepared by a number of methods known to those skilled in the art. For example, cellulose esters can be prepared by heterogeneous acylation of cellulose in a mixture of carboxylic acid and anhydride in the presence of a catalyst such as H2SO4. Cellulose triesters can also be prepared by homogeneous acylation of cellulose dissolved in a suitable solvent such as LiCl / DMAc or LiCl / NMP.

[0040] Those skilled in the art will understand that the commercial term "cellulose triester" also includes cellulose esters that are not completely 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.

[0041] After esterification of cellulose to triester, some of the acyl substituents may be removed by hydrolysis or alcohol decomposition to obtain a secondary cellulose ester. As mentioned earlier, the distribution of acyl substituents may be random or non-random depending on the specific method used. Alternatively, the secondary cellulose ester may be prepared directly without hydrolysis by using a limited amount of acylation reagent. This process is particularly useful when the reaction is carried out in a solvent that dissolves cellulose. All of these methods yield cellulose esters useful in the present invention.

[0042] In one embodiment, or in combination with any of the embodiments mentioned, the cellulose acetate is a cellulose diacetate having a polystyrene-equivalent number-average molecular weight (Mn) of about 10,000 to about 100,000, as measured by gel permeation chromatography (GPC) using NMP as the solvent and polystyrene-equivalent Mn according to ASTM D6474. In one embodiment, or in combination with any other embodiment, the cellulose acetate composition, when measured by gel permeation chromatography (GPC) according to ASTM D6474 using NMP as the solvent, has a range of 10,000 to 90,000, or 10,000 to 80,000, or 10,000 to 70,000, or 10,000 to 60,000, or less than 10,000 to 60,000, or less than 10,000 to 55,000, or 10,000 to 50,000, or less than 10,000 to 50,000, or less than 10,000 to 45,000, or 10,000 to 40,000, or 10,000 to 30,000, or 20,000. 00 to less than 60,000, or 20,000 to less than 55,000, or 20,000 to less than 50,000, or 20,000 to less than 50,000, or 20,000 to less than 45,000, or 20,000 to 40,000, or 20,000 to 35,000, or 20,000 to 30,000, or 30,000 to 60,000 It contains cellulose diacetate having a polystyrene-equivalent number-average molecular weight (Mn) of less than 00, or between 30,000 and less than 55,000, or between 30,000 and less than 50,000, or between 30,000 and less than 45,000, or between 30,000 and 40,000, or between 30,000 and 35,000.

[0043] The most common commercially available secondary cellulose esters are produced by forming cellulose triesters through the initial heterogeneous acylation of cellulose using an acid catalyst. After obtaining a homogeneous solution of the cellulose triester in the corresponding carboxylic acid, the cellulose triester is then subjected to hydrolysis until the desired degree of substitution is obtained. After isolation, random secondary cellulose esters are obtained, i.e., the relative degree of substitution (RDS) at each hydroxyl group is approximately equal.

[0044] The cellulose esters useful in the present invention can be prepared using techniques known in the art, and can also be selected from various types of cellulose esters available from, for example, Eastman Chemical Company, Kingsport, TN, USA, such as Eastman® Cellulose Acetate CA398-30 and Eastman® Cellulose Acetate CA398-10, Eastman® CAP485-20 Cellulose Acetate Propionate, and Eastman® CAB381-2 Cellulose Acetate Butyrate.

[0045] In one embodiment, or in combination with any other embodiment, cellulose esters can be prepared by converting cellulose to cellulose esters using a reactant obtained from a recycled material, such as a recycled plastic-containing synthesis gas source. In one embodiment, or in combination with any other embodiment, such reactant may be a cellulose reactant comprising an organic acid and / or acid anhydride used in a cellulose esterification or acylation reaction, such as those discussed herein.

[0046] In one embodiment of the present invention, or in combination with any of the embodiments mentioned, or in combination with any of the embodiments mentioned, a cellulose ester composition is provided comprising at least one regenerated cellulose ester, wherein the cellulose ester has at least one substituent on anhydrous glucose units (AU) derived from a regenerated material (e.g., recycled plastic-containing synthesis gas).

[0047] In one embodiment, or in combination with any other embodiment, the cellulose ester composition contains 50-99% by weight, or 60-99% by weight, or 70-99% by weight, or 80-99% by weight, 50-98% by weight, or 60-98% by weight, or 70-98% by weight, or 80-98% by weight, or 90-98% by weight, 50-90% by weight, or 60-90% by weight, or 70-90% by weight, or 80-90% by weight, or 90-99% by weight, or 50-80% by weight, or 60-80% by weight, or 70-80% by weight, or 50-70% by weight, or 60-70% by weight, or 50-60% by weight, based on the total weight of the cellulose ester composition. In some embodiments, the cellulose ester used herein may include a combination, blend, or mixture of two or more different types of cellulose esters. For example, in some embodiments, the cellulose esters used herein may consist of a blend of two or more cellulose esters having different DSACs, provided that this blend has a total DSAC of 2.2 to 2.8 or 2.0 to 2.9.

[0048] plasticizer In one embodiment, or in combination with any other embodiment, the cellulose ester compositions described herein may contain at least one plasticizer. The plasticizer reduces the melting temperature, i.e., Tg, and / or melt viscosity of the cellulose ester. Cellulose ester plasticizers include glycerol triacetate (triacetin), glycerol diacetate (diacetin), dibutyl terephthalate, dimethyl phthalate, diethyl phthalate, polyethylene glycol (molecular weight 200-600), dibutyl tartrate, di-2-methoxyethyl phthalate, ethyl o-benzoyl benzoate, triethylene glycol dipropionate, 1,2-epoxypropylphenylethylene glycol, 1,2-epoxypropyl (m-cresyl)ethylene glycol, 1,2-epoxypropyl (o-cresyl)ethylene glycol, β-oxyethylcyclohexene carboxylate, bis(cyclohexanate)diethylene glycol, triethyl citrate, polyethylene glycol, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, tributyl acetyl citrate, Admex, trippropionine, Scandiflex, poloxamer copolymer, and poly Ethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and glycol tribenzoate, benzoate-containing plasticizers such as the Benzoflex® plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, o-cresyl p-toluenesulfonate, n-ethyltoluenesulfonamide, adipate-based plasticizers, soybean oil epoxides such as the Paraplex® plasticizer series, sucrose-based plasticizers, di Possible materials include butyl sebacate, tributylin, sucrose acetate isobutyrate, Resolflex® series plasticizers, triphenyl phosphate (TPP), triethyl phosphate (TEP), glycolates (ethylphthalyl ethyl glycolate "EPEG" and methylphthalyl ethyl glycolate "MPEG"), methoxypolyethylene glycol, 2,2,4-trimethylpentane-1,3-diirbis(2-methylpropanoate), and polycaprolactone.In some embodiments, the plasticizers used herein may include a combination or mixture of two or more different types of plasticizers.

[0049] In one embodiment, or in combination with any other embodiment referenced herein, the material has a boiling point of at least 100°C, or at least 200°C, and / or 400°C or less, or 300°C or less.

[0050] In one embodiment, or in combination with any other embodiment, the plasticizer is a food-compatible plasticizer. Food compatibility means that it complies with applicable food additive and / or food contact regulations, and the plasticizer is permitted for use or recognized as safe by at least one (national or regional) food safety regulatory authority (or organization), for example, listed in the 21 CFR Food Additive Regulations, or otherwise recognized by the U.S. FDA with a Certificate of Gravity for Use (GRAS). In one embodiment, or in combination with any other embodiment, the food-compatible plasticizer is triacetin or polyethylene glycol (PEG) having a molecular weight of about 200 to about 600. In one embodiment, or in combination with any other embodiment, possible examples of food-compatible plasticizers include triacetin, triethyl citrate, polyethylene glycol, Benzoflex, propylene glycol, polysorbate, sucrose octaacetate, acetylated triethyl citrate, tributyl acetyl citrate, Admex, trippropionine, Scandiflex, poloxamer copolymer, polyethylene glycol succinate, diisobutyl adipate, polyvinylpyrrolidone, and glycol tribenzoate.

[0051] In one embodiment, or in combination with any other embodiment, the plasticizer may be present in an amount sufficient to enable the cellulose ester composition to be melt-processed (or thermoformed) in a conventional melt-processing apparatus to produce useful articles, such as disposable plastic products. In one embodiment, or in combination with any other embodiment, the plasticizer may be present in an amount of 1 to 40% by weight, or 5 to 25% by weight, or 10 to 25% by weight, or 12 to 20% by weight, based on the weight of the cellulose ester composition, for most thermoplastic processing. In one embodiment, or in combination with any other embodiment, profile extrusion, sheet extrusion, thermoforming, and injection molding can be achieved with plasticizer levels ranging from 10 to 30%, or 12 to 25%, or 15 to 20%, or 10 to 25% by weight, based on the weight of the cellulose ester composition.

[0052] 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, benzoic acid-containing plasticizers such as the Benzoflex® plasticizer series, poly(alkyl succinates) such as poly(butyl succinate), polyethersulfone, adipic acid-based plasticizers, soybean oil epoxides such as the Paraplex® plasticizer series, sucrose-based plasticizers, dibutyl sebacate, tributylin, plasticizers in the Resolflex® series, triphenyl phosphate, glycolic acid, polyethylene glycol, 2,2,4-trimethylpentane-1,3-diirbis(2-methylpropanoate), and polycaprolactone.

[0053] In one embodiment, or in combination with any other embodiment, the cellulose ester composition may contain a plasticizer selected from the group consisting of PEG and MPEG (methoxyPEG). The polyethylene glycol or methoxy polyethylene glycol composition has an average molecular weight of 200 to 600 daltons, and the composition is melt-workable, biodegradable, and disintegrable.

[0054] In one embodiment, or in combination with any other embodiment, the composition comprises polyethylene glycol or methoxyPEG having an average molecular weight of 300 to 550 daltons.

[0055] 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.

[0056] In one embodiment, or in combination with any other embodiment, the cellulose ester composition contains at least one plasticizer (as described herein) in an amount based on the total weight of the cellulose ester composition of 1-40% by weight, or 5-40% by weight, or 10-40% by weight, or 12-40% by weight, 13-40% by weight, or 15-40% by weight, or more than 15-40% by weight, or 17-40% by weight, or 20-40% by weight, or 25-40% by weight, or 5-35% by weight, or 10-35% by weight, or 13-35% by weight, or 15-35% by weight, or more than 15-35% by weight, or 17-35% by weight, or 20-35% by weight, or 5-30% by weight, or 10-30% by weight. , or containing in amounts of 13-30% by weight, or 15-30% by weight, or more than 15-30% by weight, or 17-30% by weight, or 5-25% by weight, or 10-25% by weight, or 13-25% by weight, or 15-25% by weight, or more than 15-25% by weight, or 17-25% by weight, or 5-20% by weight, or 10-20% by weight, or 13-20% by weight, or 15-20% by weight, or more than 15-20% by weight, or 17-20% by weight, or 5-17% by weight, or 10-17% by weight, or 13-17% by weight, or 15-17% by weight, or more than 15-17% by weight, or less than 5-17% by weight, or less than 10-17% by weight, or less than 13-17% by weight, or less than 15-17% by weight.

[0057] In one embodiment, or in combination with any other embodiment, at least one plasticizer includes or is a food-grade plasticizer or an FDA-approved plasticizer. The food-grade plasticizer or FDA-approved plasticizer includes or is triacetin or PEG (MW300-500).

[0058] Biodegradable polymers In one embodiment, or in combination with any other embodiment, the cellulose ester composition described herein comprises a BCE component comprising at least one biodegradable cellulose ester (BCE) which may comprise one or more of the cellulose esters described herein, and a biodegradable polymer component comprising at least one other biodegradable polymer (other than BCE). In one embodiment, or in combination with any other embodiment, the other biodegradable polymer can be selected from polyhydroxyalkanoates (PHA and PHB), polylactic acid (PLA), poly(glycolic acid) (PGA), polycaprolactone polymer (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.

[0059] In one embodiment, or in combination with any other embodiment, the cellulose ester compositions described herein include a cellulose ester blend with one or more biodegradable polymers that can enhance the melt strength and / or elasticity of the composition. Particularly preferred biodegradable polymers include those that are highly biodegradable, have a low Tg (e.g., below room temperature), and / or have a low modulus of elasticity.

[0060] 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, when combined with cellulose acetate, may result in an increased blow-up ratio.

[0061] 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-adipate (PBSA)), polyhydroxyalkanoates (PHA and PHB), polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), starch (including modified starch), and combinations thereof. In some such embodiments, these biodegradable polymers, when combined with cellulose acetate propionate (CAP) and / or cellulose acetate butyrate (CAB), may result in an increased blow-up ratio.

[0062] 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% by weight, or 1 to 40% by weight, or 1 to 30% by weight, or 1 to 25% by weight, or 1 to 20% by weight, 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% by weight, or 1 to 40% by weight, or 1 to 30% by weight, or 1 to 25% by weight, or 1 to 20% by weight, based on the total amount of BCE and biodegradable polymer. In one embodiment, or in combination with any other embodiment, at least one biodegradable polymer has a weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC) with methylene chloride as the solvent using a refractive index detector and a polystyrene standard, which is 10,000 to 1,000,000, or 50,000 to 1,000,000, or 100,000 to 1,000,000, or 2 The PHA comprises a range of 50,000 to 1,000,000, or 500,000 to 1,000,000, or 600,000 to 1,000,000, or 600,000 to 900,000, or 700,000 to 800,000, or 10,000 to 500,000, or 10,000 to 250,000, or 10,000 to 100,000, or 10,000 to 50,000. In one embodiment, or in combination with any other embodiment, the PHA may comprise polyhydroxybutyrate-co-hydroxyhexanoate.

[0063] Nuclear agent A nucleating agent refers to a chemical or physical material that provides sites for cell formation in a mixture of molten formulations, such as within a CE molten composition. As will be described in more detail below, nucleating agents can be added to the formulated CE material during the formulation process. Alternatively, or in addition, nucleating agents may be added during the manufacturing process of the foamed sheet. For example, a nucleating agent may be blended with the formulation introduced into the hopper of the extruder in the extrusion section. Alternatively, a nucleating agent may be added to the CE molten composition in the extruder itself. Examples of nucleating agents include physical nucleating agents and chemical nucleating agents. A physical nucleating agent is a substance that is immiscible with the polymer matrix of the CE molten composition at the extrusion temperature of the extrusion section. A chemical nucleating agent is a substance that reacts (e.g., decomposes) during extrusion (e.g., at the extrusion temperature in the extruder) to form a physical nucleating agent. Thus, a chemical nucleating agent can be considered (and referred to herein as) a precursor of a physical nucleating agent formed in situ.

[0064] Suitable physical nucleating agents include fine particles having a desired particle size and / or shape to create cell nucleation sites within the CE molten composition. For example, in some embodiments, the physical nucleating agent has an average particle size of less than 1000 microns, less than 500 microns, less than 100 microns, less than 50 microns, less than 25 microns, less than 20 microns, less than 10 microns, less than 5 microns, less than 2 microns, less than 1.5 microns, and / or less than 1.0 micron. However, in some other embodiments, it may be preferable to have nanoscale-sized particles. Furthermore, in some embodiments, the physical nucleating agent preferably has a high aspect ratio (i.e., width:height). For example, in some embodiments, the physical nucleating agent has an average aspect ratio 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. Furthermore, as described above, the physical nucleating agent must be immiscible with the polymer matrix of the CE molten composition at the extrusion temperature of the extrusion section. Therefore, in some embodiments, the physical nucleating agent needs to have a melting temperature of at least 220°C, at least 230°C, at least 240°C, at least 250°C, at least 275°C, at least 300°C, at least 325°C, or at least 350°C. However, the physical nucleating agent may be selected to have the ability to recrystallize after cooling following melting.

[0065] Examples of suitable inorganic physical nucleating agents include, but are not limited to, talc, minerals such as CaCO3 and mica, and mixtures of at least two of the above. One representative example is Heritage Plastics HT6000 Linear Low Density Polyethylene (LLDPE) Based Talc Concentrate. Other inorganic physical nucleating agents include wollastonite, silica, silicon dioxide, titanium dioxide, 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 includes oxides such as metal oxides or mixed metal oxides, 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 dioxide, and titanium dioxide. In other embodiments, the inorganic nucleating agent includes silicates such as magnesium silicate and calcium silicate, selected from one or more of the following:

[0066] Biodegradable natural particulate matter derived from renewable organic sources (e.g., organic nucleating agents) has also been found to function as effective physical nucleating agents. Natural substances that can be physical nucleating agents include substances composed of cellulose fibers and / or cellulose starch. Examples, but not limited to, include almond husk powder, animal fiber, apricot husk powder, bamboo powder, bark powder, shell powder, coconut husk powder, coconut fiber, cork powder, corn cob powder, corn cob grit, cottonseed husks, flocs and fibers, hazelnut husk powder, kenaf powder, natural fiber, nut shells and powders, oat fiber powder, olive stone powder, peanut shell powder, pecan husk powder, pine nut husk powder, pistachio nut husk powder, plant fiber, rice husk powder, rice husk grit, rice husks, soybean powder, starch powder (hydrophobic), walnut husk powder, wheat husk, wheat hull, and wood powder. Other organic physical nucleating agents include cellulose powder, chitin, chitosan, metal stearate, carbon black, and dolomite.

[0067] As described above, a suitable chemical nucleating agent (or a precursor to a physical nucleating agent formed in situ) is configured to decompose when a threshold chemical reaction temperature is reached, generating cell nucleating sites in the CE molten composition. These small cells serve as nucleating sites for the proliferation of larger cells from physical or other types of blowing agents. In some embodiments, the precursor is configured to form a gas such as CO2 or N2 during the extrusion of particulate material.

[0068] Examples of chemical nucleating agents include, but are not limited to, acids such as citric acid or citric acid-based materials. Other acids may include lauric acid, stearic acid, tartaric acid, ascorbic acid, propionic acid, and hexanoic acid. A typical example is HYDROCEROL™ CF-40E (available from Clariant Corporation), which contains citric acid and a nucleating agent. In some embodiments, the chemical nucleating agent includes a combination of acid and base, such as a carbonate, and examples of carbonates include sodium bicarbonate, zinc bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate. For example, a typical example of a chemical nucleating agent is a combination of citric acid and sodium bicarbonate. In some embodiments, the chemical nucleating agent may include a carrier in which the active ingredient of the nucleating agent is dispersed. For example, yet another typical example of a chemical nucleating agent is a combination of citric acid, sodium bicarbonate, and a carrier. In some embodiments, the carrier may include polystyrene. However, the carrier may include other compositions such as various biopolymers (e.g., polybutylene succinate, Capa polyester, etc.), polyolefins, and acrylic copolymers (e.g., ethylene methyl acrylate). In some such embodiments, citric acid and sodium bicarbonate may constitute about half (by weight) of the chemical nucleating agent, while the carrier constitutes the remaining half (by weight). Furthermore, in some such embodiments, there may be more sodium bicarbonate than citric acid in the chemical nucleating agent. For example, there may be about three times (by weight) more sodium bicarbonate than citric acid in the chemical nucleating agent. It should also be understood that in some embodiments, such as when the nucleating agent is hecofoam or hydrocerol, a carrier may not be required or used.

[0069] In one embodiment or in combination with any of the embodiments referenced herein, the nucleating agents are present in amounts of 0.1 to 10% by weight, 0.1 to 5.0% by weight, at least 0.1% by weight, at least 0.25% by weight, at least 0.5% by weight, at least 1.0% by weight, at least 1.25% by weight, at least 1.5% by weight, at least 1.75% by weight, at least 2.0% by weight, at least 2.25% by weight, at least 2.5% by weight, at least 2.75% by weight, or at least 3.0% by weight, or at least 3.5% by weight, or at least 4.0% by weight, or at least 4.5% by weight, and / or less than 7.5% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, or less than 1.0% by weight, based on the total weight of the cellulose ester composition. In some embodiments, the nucleating agents used herein may include combinations or mixtures of two or more different types of nucleating agents.

[0070] It should be noted that cellulose ester materials, whether in the form of compounded CE materials or CE molten compositions, can generally tolerate a maximum amount of nucleating agent capable of functioning to form nucleating sites. Any remaining nucleating agent added to the cellulose ester material remains as a filler. Depending on the type of filler used, the filler can provide various properties to the resulting cellulose ester foam and / or article. For example, some fillers can increase / decrease the density, ductility, Young's modulus, yield strength, thermal deflection temperature, permeability, impact resistance, elongation to fracture, adhesion properties, and biodegradability of the cellulose ester material. Fillers can also be used to alter the visual properties (e.g., color, opacity, etc.) and tactile properties (e.g., material continuity, surface roughness, etc.) of the cellulose ester material.

[0071] foaming agent A blowing agent refers to a physical or chemical material (or combination of materials) that acts to expand nucleating sites. Blowing agents may include chemical blowing agents, physical blowing agents, combinations thereof, or several types of chemical and physical blowing agents. Blowing agents function to reduce the density of the material by expanding the cells formed in the molten composition at the nucleating sites. Blowing agents may be added to the CE molten composition in an extruder. It has been surprisingly found that, due to the hygroscopic nature of biodegradable particulate natural fillers, they can absorb moisture and carry the absorbed water into the molten composition mixture, where it can act as a physical blowing agent.

[0072] Examples of physical blowing agents include H2O, N2, CO2, alkanes, alkenes, ethers, ketones, argon, helium, air, or mixtures thereof. Furthermore, it has been surprisingly discovered that the hygroscopic nature of biodegradable particulate natural fillers allows them to absorb moisture, transport the absorbed water into the molten resin mixture, where it can act as a physical blowing agent. Hygroscopic and biodegradable natural fillers can be incorporated into the composition to allow them to absorb moisture before the foaming process, after which the water is released and acts as a physical blowing agent. Beneficially, water can also be used as a plasticizer for cellulose ester resins. Additionally, in some embodiments, the physical blowing agent may include hydrocarbons such as pentane / isopentane or butane / isobutane. Other hydrocarbons may include propane, ethane, methane, hexane, cyclohexane, cyclopentane, or cyclobutene.

[0073] Chemical blowing agents are materials that decompose or react to produce gases (e.g., CO2 or N2). Such gases expand cells in the molten resin mixture and / or the resulting foam mixture, creating a structural material with multiple gaseous voids that are dispersed throughout. Chemical blowing agents can be endothermic or exothermic. Chemical blowing agents typically decompose and release gases at a certain temperature. Examples of chemical blowing agents include azodicarbonamides, acids (e.g., citric acid), and carbonates (e.g., sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, zinc carbonate, etc.), and combinations thereof.

[0074] In one embodiment, or in combination with any of the embodiments referred to herein, the above-mentioned blowing agent can be combined with a secondary blowing agent (or co-blowing agent). In some embodiments, the co-blowing agent is selected from the group consisting of methyl acetate, ethanol, ketones (e.g., acetone), and mixtures thereof.

[0075] In one embodiment, or in combination with any of the embodiments referenced herein, the blowing agent (and any co-blowing agent) is present in an amount of 0.3 to 1.5% by weight, or 0.3 to 2.0% by weight, or 0.3 to 2.5% by weight, or 0.3 to 3.0% by weight, or 0.3 to 3.5% by weight, or 0.3 to 4.0% by weight, or 0.3 to 8%, or 1.3 to 1.5% by weight, or 1.3% by weight, based on the total weight of the cellulose ester composition. ~2.0% by weight, or 1.3~2.5% by weight, or 1.3~3.0% by weight, or 1.3~3.5% by weight, or 1.3~4.0% by weight, or 1.3~4.5% by weight, or 1.3~5.0% by weight, or 1.3~5.5% by weight, or 1.5~3.0% by weight, or 1.5~4.0% by weight, or 1.5~5.0% by weight, or 1.5~6.0% by weight, or 2.0~3.0% by weight, or 2.0~4.0% by weight, or 2.0-5.0% by weight, or 2.0-6.0% by weight, or 2.5-3.0% by weight, or 2.5-4.0% by weight, or 2.5-5.0% by weight, or 2.5-6.0% by weight, or 3.0-4.0% by weight, or 3.0-5.0% by weight, or 3.0-6.0% by weight, or 0.0-9.0% by weight, or 0.5-9.0% by weight, or 1.0-9.0% by weight, or 1.5-9.0% by weight, or 2.0-9.0 It is present in amounts of weight %, or 2.5 to 9.0 by weight, or 3.0 to 9.0 by weight, or 3.5 to 9.0 by weight, or 4.0 to 9.0 by weight, or 4.5 to 9.0 by weight, or 5.0 to 9.0 by weight, or 5.5 to 9.0 by weight, or 6.0 to 9.0 by weight, or 6.5 to 9.0 by weight, or 7.0 to 9.0 by weight, or 7.5 to 9.0 by weight, or 8.0 to 9.0 by weight, or 8.5 to 9.0 by weight. In some embodiments, the blowing agent used herein may include a combination or mixture of two or more different types of blowing agents.

[0076] Surface modification additives Surface modifiers refer to materials that can be added to cellulose ester compositions to improve their processability, thereby modifying the structure of the composition (or the resulting foamed article). For example, the inventors of this application have found that adding surface modifiers to compounded CE materials (e.g., pellets in the compounding process) or CE molten compositions (e.g., in the extrusion process) can improve the processability of the CE molten composition by reducing undesirable adhesion to the die or mandrel (or other components in the foamed sheet manufacturing process). Such reduction in adhesion can be achieved by the surface modifier suppressing the fusion of cellulose esters caused by plasticizers. The addition of surface modifiers can also reduce blocking of cellulose ester foamed sheets produced in the sheet forming section. Furthermore, surface modifiers can also improve the foamed sheet manufacturing process by enabling the process to be carried out at lower temperatures and / or by enabling an increase in the blow-up ratio when the molten composition is stretched on the forming mandrel.

[0077] Furthermore, in some embodiments, the surface modification additive may function as an antistatic additive to suppress electrical sparks or arc discharges in the CE molten composition. Suppression of electrical sparks or arc discharges can be particularly important to reduce the possibility of hydrocarbons igniting and causing a fire when hydrocarbons are used as blowing agents. Beneficially, the surface modification additive may also reduce the diffusion of blowing agents, such as hydrocarbons, from the foamed sheet or the resulting article. In some embodiments, hydrocarbons themselves can be used as surface modification additives.

[0078] Nevertheless, more common examples of surface modifying additives that can be used with the compounded CE material (e.g., during the compounding process) or with the CE melted composition (e.g., during the foamed sheet manufacturing process) according to embodiments of the present invention include fatty acids such as palmitic acid, tallow acid, stearic acid, oleic acid, linoleic acid and linolenic acid, arachidic acid / behenic acid, behenic acid, and erucic acid. Surface modifying additives may also include fatty acid amides such as erucamide, oleoamide, stearamide, benamide, secondary amide, and bisamide.

[0079] Examples of additional surface modification additives may include glycerol esters and / or stearate esters such as monoglycerides, diglycerides, and triglycerides. Examples of monoglycerides include glycerol monostearate or monoglyceride derivatives (such as diacetyltartrate esters of mono and diglycerides (DATEM), ethoxylated monoglycerides, succinyl monoglycerides, and propylene glycol monoesters (PGME)). Examples of surface modification additives may also include metal stearate salts such as aluminum stearate, calcium stearate, lithium stearate, magnesium stearate, sodium stearate, zinc stearate, and / or combinations thereof (e.g., calcium stearate / zinc stearate). Examples of surface modifying additives include waxes such as polyolefin waxes (polypropylene wax and polyethylene wax), olefin oxide waxes, ethylene acrylic acid (EAA) copolymer waxes, ethylene methyl acrylate (EMA) copolymer waxes, EAA ionomer shafts, acrylic waxes, and / or natural waxes (such as rice bran wax, sunflower wax, sugarcane wax, candelilla wax, soybean wax, beeswax, caddelilla wax, and carnauba wax).

[0080] Other non-exclusive examples of surface modification additives include aliphatic diesters (e.g., dioctyl adipate), polyglycol diesters, alkyl alkyl ether diesters, aromatic triesters, polyester resins, chlorinated hydrocarbons, halogenated hydrocarbons, alkyl ether monoesters, and alkyl monoesters. Further, various oils such as aromatic oils, naphthenic oils, glyceride oils, silicone oils, and epoxidized oils (e.g., soybean oil and linseed oil) can be used as surface modification additives. Thus, in some embodiments, the surface modification additive includes plasticizers such as aliphatic diester plasticizers and polyester plasticizers. Further, in some embodiments, the surface modification additive may include polyhedral oligomeric silsesquioxane (POSS).

[0081] More generally, the surface modification additive used in embodiments of the present invention may be less polar than the cellulose ester in the formulated CE material (e.g., during the formulation process) or the CE melt composition (e.g., during the foamed sheet manufacturing process). For example, the surface modification additive may have (based on the Hansen solubility parameter) a total solubility parameter δ of less than 25 MPa, less than 20 MPa, or less than 19.5 MPa; a dispersion force solubility parameter δ of less than 18 MPa, less than 16 MPa, or less than 14 MPa; and / or a dipolar intermolecular force solubility parameter δ of less than 12 MPa, less than 8 MPa, or less than 4 MPa; and / or a hydrogen bond solubility parameter δ of less than 11 MPa, less than 10 MPa, or less than 9 MPa. 1 / 2 less than, 20 MPa 1 / 2 less than, or 19.5 MPa 1 / 2 less than total solubility parameter δ; 18 MPa 1 / 2 less than, 16 MPa 1 / 2 less than, or 14 MPa 1 / 2 less than dispersion force solubility parameter δ d ; 12 MPa 1 / 2 less than, 8 MPa 1 / 2 less than, or 4 MPa 1 / 2 less than dipolar intermolecular force solubility parameter δ d ; and / or 11 MPa 1 / 2 less than, 10 MPa 1 / 2 less than, or 9 MPa 1 / 2 less than hydrogen bond solubility parameter δ hIt may have the following properties. On the other hand, in some other embodiments, the surface modification additive used in embodiments of the present invention may have higher polarity than the cellulose ester in the compounded CE material (e.g., during the compounding process) or the CE melt composition (e.g., during the foam sheet manufacturing process). For example, the surface modification additive may have a polarity of 21.5 MPa (based on the Hansen solubility parameter). 1 / 2 Super, 23MPa 1 / 2 Over, or 25 MPa 1 / 2 The total solubility parameter δ may be greater than or equal to 200°C, 220°C, 240°C, 260°C, 280°C, or 300°C. Furthermore, the surface modification additive may have a molecular weight greater than 100 g / mol, 150 g / mol, 220 g / mol, 260 g / mol, 300 g / mol, or 340 g / mol, and / or less than or equal to 1000 g / mol, less than or equal to 2500 g / mol, or less than or equal to 5000 g / mol. Furthermore, it may be preferable that the surface modification additive is insoluble in the plasticizer(s) used in the cellulose ester composition. For example, it may be preferable that the surface modification additive is insoluble in triacetin. Finally, in some embodiments, the surface modification additive may be biodegradable and / or food-safe or FDA-approved.

[0082] In one embodiment, or in combination with any of the embodiments referenced herein, the surface modifiers are all present in amounts of 0.05 to 0.75% by weight, or 0.05 to 1.0% by weight, or 0.05 to 2.5% by weight, or 0.05 to 5.0% by weight, or 0.75 to 1.0% by weight, or 0.75 to 2.5% by weight, or 0.75 to 5.0% by weight, or 0.1 to 1.0% by weight, or 0.1 to 2.5% by weight, or 0.1 to 5.0% by weight, or 1.0 to 2.5% by weight, or 1.0 to 5.0% by weight, or 2.5 to 5.0% by weight, based on the total weight of the cellulose ester composition. In some embodiments, the surface modifiers used herein may include combinations or mixtures of two or more different types of surface modifiers.

[0083] Melt strength improver The elasticity of a cellulose ester composition, particularly its elasticity during heating processes such as extrusion and thermoforming, can be increased by including one or more melt strength improvers. Such melt strength improvers may be in the form of functional ionic components. A variety of compounds and materials can be used, as long as they contain ionic functional groups. For example, in some embodiments, the functional ionic component is selected from the group consisting of acacia rubber, sulfopolyesters, quaternary salts, ionomers, ionic liquids, ionic waxes, and mixtures thereof.

[0084] Goods Extruded sheets of cellulose ester foam may be formed using the extrusion and / or sheet molding sections described above. Such extruded sheets comprise a structural material having a plurality of gas voids arranged throughout. Such gas voids are formed by the expansion of a foaming agent in the form of a gas within a cellulose polymer molten material. The structural material is cellulose ester-based, and specific amounts of the constituent components of the structural material (e.g., cellulose ester, plasticizer, nucleating agent, surface modifying additive, etc.) are described in more detail above. Articles may be molded from extruded sheets of foam according to embodiments and may be particularly useful in the food service industry. An exemplary article is a meat tray. This article may have one or more particularly advantageous properties. For example, the article may be biodegradable and / or compostable, and / or the article may have excellent mechanical properties (e.g., strength, density, cell size, absorption, etc.).

[0085] In one embodiment, or in combination with any of the embodiments referred to herein, the foam is 0.20 g / cm³ 3 Less than 0.18 g / cm³ 3 Less than 0.15 g / cm³ 3 Less than 0.12 g / cm³ 3 Less than 0.10 g / cm³ 3 Less than 0.08 g / cm³ 3 Less than 0.06 g / cm³ 3 Less than 0.04 g / cm³ 3 Less than 0.04-0.8 g / cm³3 、0.04~0.6g / cm 3 、0.04~0.5g / cm 3 、0.04~0.4g / cm 3 、0.04~0.3g / cm 3 、0.04~0.2g / cm 3 、0.04~0.15g / cm 3 、0.04~0.12g / cm 3 、0.04~0.10g / cm 3 、0.04~0.08g / cm 3 、0.04~0.06g / cm 3 、または0.05~0.8g / cm 3 、0.05~0.6g / cm 3 、0.05~0.5g / cm 3 、0.05~0.4g / cm 3 、0.05~0.3g / cm 3 、0.05~0.2g / cm 3 、0.05~0.15g / cm 3 、0.05~0.12g / cm 3 、0.05~0.10g / cm 3 、0.05~0.08g / cm 3 、0.06~0.8g / cm 3 、0.06~0.6g / cm 3 、0.06~0.5g / cm 3 、0.06~0.4g / cm 3 、0.06~0.3g / cm 3 、0.06~0.2g / cm 3 、0.06~0.15g / cm 3 、0.06~0.12g / cm 3 、0.06~0.10g / cm 3 、0.06~0.08g / cm 3 、0.08~0.8g / cm 3 、0.08~0.6g / cm 3 、0.08~0.5g / cm 3 、0.08~0.4g / cm 3 、0.08~0.3g / cm 3 、0.08~0.2g / cm 3 、0.08~0.15g / cm 3, 0.08~0.12 g / cm³ 3 , 0.08~0.10 g / cm³ 3 , 0.1~0.8 g / cm³ 3 , 0.1~0.6 g / cm³ 3 , 0.1~0.5 g / cm³ 3 , 0.1~0.4 g / cm³ 3 , 0.1~0.3 g / cm³ 3 , 0.1~0.2 g / cm³ 3 , 0.1~0.15 g / cm³ 3 , 0.1~0.12 g / cm³ 3 , 0.2~0.8 g / cm³ 3 , 0.2~0.6 g / cm³ 3 , 0.2~0.5 g / cm³ 3 , 0.2~0.4 g / cm³ 3 , 0.2~0.3 g / cm³ 3 , 0.3~0.6 g / cm³ 3 , 0.3~0.5 g / cm 3 , 0.3~0.4 g / cm³ 3 , 0.4~0.6 g / cm³ 3 , 0.4~0.5 g / cm 3 , or 0.5~0.6 g / cm³ 3 It has a density of .

[0086] In one embodiment, or in combination with any of the embodiments referenced 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~600μm, or 400μm~600μm, or 500μm~600μm, or 40μm~550μm, or 40μm~500μm, or 40μm~450μm, or 40μm~400μm, or 40μm~350μm, or 40μm~300μm, or 40μm~250μm, or 40μm~200μm, or 40μm~150μm, or 40μm~100μm.

[0087] Concepts of further inventions relating to processes and systems for manufacturing pellets, foam sheets, and / or articles. As described above, embodiments of the present invention provide processes and systems for producing biodegradable cellulose ester compositions, sheets, and articles. In particular, it is possible to achieve and / or increase the optimal and maximum blow-up ratio (BUR), thereby maximizing the amount of usable foamed sheet material that can be produced in the sheet molding 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 enhance elasticity.

[0088] The embodiments described herein are particularly useful for the manufacture of cellulose ester foam sheets and articles, but the embodiments can be used for the manufacture of other sheets and articles.

[0089] In one embodiment, or in combination with any of the embodiments referred to herein, biodegradable cellulose acetate foams or articles that are industrial or household compostable can be produced. In one subclass of this class, the foam or article is industrial compostable. In one subclass of this subclass, the foam or article has a thickness of less than 6 mm. In one subclass of this subclass, the foam or article has a thickness of less than 3 mm. In one subclass of this subclass, the article has a thickness of less than 1.1 mm. In one subclass of this class, the foam or article is household compostable. In one subclass of this subclass, the foam or article has a thickness of less than 6 mm. In one subclass of this subclass, the foam or article has a thickness of less than 3 mm. In one subclass of this subclass, the foam or article has a thickness of less than 1.1 mm. In one subclass of this subclass, the foam or article has a thickness of less than 0.8 mm. In one subclass of this subclass, the foam or article has a thickness of less than 0.6 mm. In another subclass of this subclass, the foam or article has a thickness of less than 0.4 mm.

[0090] In one embodiment, or in combination with any of the embodiments referenced herein, the thickness of the foam or article is 1–10 mm, 1–8 mm, 2–8 mm, 3–7 mm, 4–6 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 may have other, larger sizes. For example, in some embodiments, the foam or article may have a thickness of 0.5–24 inches, 1–15 inches, or 3–12 inches. In some embodiments, the foam or article may have a thickness of 100–400 mils, 120–300 mils, or 150–250 mils.

[0091] In one embodiment, or in combination with any of the embodiments referred to herein, the foam or article exhibits more than 90% collapse after 12 weeks according to the film collapse test protocol described herein.

[0092] The compositions used to produce biodegradable cellulose acetate foams may include other additives such as fillers, stabilizers, odor modifiers, waxes, compatibilizers, biodegradation accelerators, dyes, pigments, colorants, lubricants, antioxidants, viscosity modifiers, antifungal agents, heat stabilizers, antimicrobial agents, softeners, release agents, UV absorbers, and combinations thereof. Each additional additive may be present in the cellulose ester material in amounts of less than 10% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, or less than 1.0% by weight. It should be noted that for multiple categories of components in a cellulose acetate composition, the same type of compound or material may be specified or included. For example, polyethylene glycol (PEG) may function as a plasticizer or as an additive that does not function as a plasticizer, such as a hydrophilic polymer or a biodegradation accelerator. For example, low molecular weight PEG has a plasticizing effect, while high molecular weight PEG functions as a hydrophilic polymer but does not have a plasticizing effect.

[0093] In one embodiment, or in combination with any other embodiment referenced herein, the foam, composition, or foaming composition further comprises a photocatalyst. In one class of this embodiment, the photocatalyst is titanium dioxide or iron oxide. In one subclass of this class, the photocatalyst is titanium dioxide. In one subclass of this class, the photocatalyst is iron oxide.

[0094] In one embodiment, or in combination with any other embodiments referenced herein, the foam, composition, or foaming 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.

[0095] definition It should be understood that the following is not intended to be an exclusive list of the terms to be defined. Other definitions, for example, when used in context, may be provided in the explanations above.

[0096] As used herein, the terms "a," "an," and "the" mean one or more.

[0097] As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transitional clauses used to move the subject listed before the term to one or more elements listed after the term, the elements listed after the transitional clause are not necessarily the only elements that constitute the subject.

[0098] To be considered "compostable," the material must meet the following four criteria: (1) The material must pass the biodegradation requirements in tests conducted under controlled composting conditions at high temperature (58°C) according to ISO 14855-1 (2012), equivalent to 90% absolute biodegradation or 90% relative to the control polymer; (2) The material tested under aerobic composting conditions according to ISO 16929 (2013) must reach 90% disintegration; (3) The test material must meet all requirements regarding volatile solids, heavy metals, and fluorine as specified by ASTM D6400 (2012), EN 13432 (2000), and ISO 17088 (2012); (4) The material must not adversely affect plant growth.

[0099] As used herein, the term “biodegradability” generally refers to the biological transformation and consumption of organic molecules. Biodegradability is an inherent property of the material itself, and materials may exhibit different degrees of biodegradability depending on the specific conditions to which they are exposed. The term “disintegrability” refers to the tendency of a material to physically decompose into smaller fragments when exposed to specific conditions. Disintegration depends on both the material itself and the physical size and composition of the article being tested. Ecotoxicity measures the effect of a material on plants, and the heavy metal content of a material is determined according to the procedures presented in standard test methods.

[0100] For a material to be considered "biodegradable," it must exhibit at least 90 percent biodegradation in total under household composting conditions, according to French standard NFT51-800 and Australian standard AS5810 (for example, compared to the initial sample), or at least 90 percent of the maximum biodegradation of a suitable reference material after reaching a plateau for both the reference and test items. The maximum test period for biodegradation under household composting conditions is one year.

[0101] Under industrial composting conditions in accordance with ASTMD6400 and ISO17088, for an article to be considered "biodegradable," at least 90% of the organic carbon in the whole article (or each component present in amounts exceeding 1% by dry mass) must be converted to carbon dioxide by the end of the test period, compared to a control or absolute value. According to European standard ED13432 (2000), the material must exhibit at least 90 percent biodegradation in total, or at least 90 percent of the maximum biodegradation of a suitable reference material after reaching a plateau for both the reference and test items. The maximum test period for biodegradability under industrial composition conditions is 180 days.

[0102] To be considered "biodegradable" under soil composting conditions compliant with Vincotte's OK Biodegradable Soil Conformity Mark and DIN CERTCO's DIN Geprruft Biodegradable Soil Certification Scheme, the material must exhibit at least 90% biodegradation in total (e.g., compared to the initial sample), or at least 90 percent of the maximum degradation of a suitable reference material after reaching a plateau for both the reference and test items. The maximum test period for biodegradability under soil composting conditions is two years.

[0103] 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.

[0104] Claims not limited to the disclosed embodiments The preferred embodiments of the present invention described above are for illustrative purposes only and should not be used to limit the meaning of the interpretation of the scope of the invention. Modifications to the exemplary embodiments described above can be readily made by those skilled in the art without departing from the spirit of the invention.

[0105] The inventors hereby express their intention to determine and evaluate the reasonably fair scope of the invention on the basis of the doctrine of equivalents whenever the invention relates to any device that does not substantially deviate from, but falls outside, the literal scope of the invention as set forth in the following claims.

[0106] Experiment Section Abbreviation BUR is the blow-up ratio, wt% is the weight percentage, and BA is the blowing agent.

[0107] Foamed sheet samples were prepared using a Krauss Maffei tandem foaming line. The extrusion line consists of a ZE30 twin-screw extruder as the primary extruder and a KE60 single-screw extruder as the secondary cooling extruder. Compounding additives are fed into the KE30 twin-screw feeder using weight-reducing and gravimetric feeders. Physical foaming agents are injected into the primary extruder downwards to approximately 1 / 2 to 2 / 3 of the barrel. The material is extruded through a 50 mm annular die and transported on a sizing mandrel. The annular film is then cut and converted into a flat film at the roll tension / winding station.

[0108] The material composition is a cellulose acetate resin containing 15-20% by weight of processing aids and stabilizers. n-pentane is injected into the material as a blowing agent. Additional additives to the process include 1 wt% ABT1000 talc and 1% chemical blowing agent. The material was extruded in a primary extruder at 200-220°C and in a secondary extruder at 170-190°C. The line production rate was 40 kg / hour.

[0109] In foams, the blow-up ratio and lay-flat width are important factors. The blow-up ratio (BUR) is defined as the diameter of the sizing mandrel or calibration divided by the diameter of the die. The lay-flat width is the mandrel diameter multiplied by the constant PI (3.14159). [Table 1] Applications have specific stiffness requirements, which are primarily controlled by the elastic modulus of the resin and the thickness of the article. The table below shows the thicknesses of some common materials used in commercial applications today. [Table 2] Achieving the ideal target thickness of the foam is difficult. This is because, as with other extrusion processes, it is related to the production rate and extraction rate, but it is also influenced by the mandrel sizing and the effectiveness of the foam. The behavior of the foam is also influenced by many variables, including the type and level of physical blowing agent, the type and level of chemical blowing agent, the type and level of nucleating agent, temperature, and pressure.

[0110] Table 3 shows how the foam thickness at BUR 3.2 can be affected by the level of physical blowing agent. Further process optimization can achieve a maximum thickness of 5 mm. As shown in Table 2, at BUR 2.8, the thickness can be further increased to approximately 7 mm by changing the level of physical blowing agent. [Table 3] [Table 4] [Table 5]

[0111] The line rate ratio is defined as follows: Production rate (kg / min) / Line speed (M / min) = Line rate ratio (Kg / M) Line speed is the operating speed of the pull-roll assembly that winds the foam onto the rolls. The line rate ratio allows for scaling the product as the extruder size increases from small (20-40 kg / hour) to large (500-1000 kg / hour). [Table 6]

Claims

1. A foam sheet molding process, (a) Extruding a composition containing cellulose ester through an annular die having an inner die diameter (X) to form a tubular extruded object, (b) The tubular extruded material is stretched on a molding mandrel having an outer diameter of 2.1X to 3.9X, The foam sheet molding process, including the aforementioned process.

2. The foam sheet molding process according to claim 1, further comprising processing the tubular extruder to form a foam sheet.

3. The foamed sheet contains 0.05 to 0.12 g / cm³ ３ The foam sheet molding process according to claim 2, having a density of the above.

4. The foamed sheet molding process according to any one of claims 1 to 3, wherein the composition comprises 2.0 to 5% by weight of one or more physical foaming agents.

5. A foam sheet molding process according to any one of claims 1 to 4, wherein the line rate ratio is 0.10 to 0.33 kg / m.

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

7. A foam sheet molding process according to any one of claims 1 to 6, wherein the line rate ratio is 0.1 to 0.28 kg / m.

8. The foam sheet molding process according to any one of claims 2 to 4, wherein the foam sheet has a thickness of 4 to 7 mm and the outer diameter of the mandrel is 2.5X to 3.3X.

9. A foam sheet molding process according to any one of claims 2 to 4 or claim 8, wherein the line rate ratio is 0.19 to 0.33 kg / m.

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

11. A foam sheet molding process according to any one of claims 1 to 4 or claim 10, wherein the line rate ratio is 0.1 to 0.22 kg / m.

12. The foam sheet molding process according to any one of claims 1 to 11, wherein the extruded material or the foam sheet has less than 5, or less than 4, or less than 3, or less than 2 corrugations, or does not have corrugations.

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

14. The foam sheet molding process according to claim 13, wherein the composition is extruded at a temperature of at least 160°C (a).

15. The foam sheet molding process according to any one of claims 1 to 14, wherein the molding mandrel has an outer surface temperature of 30°C or higher.

16. The foam sheet molding process according to any one of claims 1 to 15, wherein the composition comprises 1% to 50% by weight of one or more polymers and / or one or more additives that function to increase the elastic and / or melt strength of the composition, based on the total weight of the composition.

17. The foam sheet molding process according to claim 16, wherein the one or more polymers have a glass transition temperature (Tg) below room temperature.

18. The foam sheet molding process according to claim 17, wherein one or more of the additives function to lower the Tg of the composition.

19. The foam sheet molding process according to any one of claims 16 or 18, wherein the one or more additives include a chemical blowing agent, a physical blowing agent, a co-blowing agent, a surface modifying additive, an elastic polymer, and a melt strength improver.

20. The foam sheet molding process according to claim 19, wherein the one or more additives include a functional ionic component as the melt strength improver.

21. The foam sheet molding process according to claim 20, wherein the functional ionic component is selected from the group consisting of acacia rubber, sulfopolyester, quaternary salt, ionomer, ionic liquid, ionic wax, and mixtures thereof.

22. The foam sheet molding process according to any one of claims 1 to 21, wherein the composition comprises a blend of 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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