Production of moldable cellulosic fiber pulp

Abstract

A method of producing moldable cellulosic fibers from a cellulosic fiber material, the method comprising: mechanically pre-treating a feedstock to form a fibrous material having a fiber length distribution such that at least 90% of the fibers have a length of less than about 40 millimeters; dewatering the fiber ingredient to produce a first filtrate and a dewatered fiber cake having a moisture content of less than about 50% (by weight); pulping the dehydrated fiber cake at a temperature in the range of 45 to 95 DEG C to produce a pulpified fiber material having a consistency of less than about 5% fiber (by weight); washing the pulpified fibrous material to produce a cake of cellulosic fibers having a consistency of at least 10% fibers (by weight) and a second filtrate; and refining the cake of cellulosic fibers in at least one disc mill to produce moldable cellulosic fibers.

Description

[0001] Related Applications

[0002] This application claims priority from Australian provisional patent application 2024902468 filed on 09 August 2024, the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates generally to the production of a cellulosic fibrous material for use, for example, in vacuum moulding, to make packaging articles such as food and produce service and supply trays and containers, as well as protective and positioning packaging for the transport or display of medical, electronic or hardware articles, and many other types of moulded packaging articles. The present invention relates to a method and apparatus for producing a mouldable cellulosic fibrous material. BACKGROUND

[0004] The following discussion of the background of the invention is intended to facilitate an understanding of the environment in which the invention is produced. It should not be read to 5 imply that any of the materials referred to are prior art to any claims that can be presented from the present application. In addition, the following description is provided largely in the context of “vacuum moulding as the end use of the mouldable cellulosic fibrous material produced by the present invention”. This is done for ease of description and should not be taken as a limitation on the end use of the material.

[0005] For thousands of years, herbaceous plants have been the primary raw material for papermaking. However, for at least a century, wood has become the primary source of fibres for papermaking raw materials, and pulping has become the dominant fibre processing technology today. In fact, the demand for pulp during that time has triggered some of the more prominent and controversial environmental and ecological issues on a global scale.

[0006] It is generally accepted that the conversion of wood to paper requires the use of heavy industrial processes that typically require very large energy inputs, large volumes of process water, and the production of large volumes of waste, and often use chemicals that create complex and even dangerous disposal and recycling requirements. In addition, whether chemical pulping or mechanical pulping, the state and geometry of the fibres in the furnish produced is typically not fully controllable, at least to the degree desired by the downstream papermaking process.

[0007] Accordingly, there has been growing interest in the development of alternative fibre crops for the production of paper products, and alternative wood pulping technologies. One source of cellulosic fibres that has been considered as a suitable alternative to wood is the banana plant.

[0008] A banana plant is a large, perennial herb with tall above-ground shoots that grow from swollen, fleshy rhizomes, an underground stem. The leaf stalks of a banana plant are arranged in a spiral in the above-ground shoots, with their long, overlapping leaf cushions (swollen bases) forming the outer part of a stout, trunk-like pseudostem, with a central growing terminal inflorescence forming the inner part, commonly referred to as the core. At higher levels, the leaf stalks bend away from the pseudostem and carry large, elliptical leaf blades (leaves) at an oblique angle. At maturity, each pseudostem will thus comprise a soft but dense core surrounded by a more robust but less dense outer part.

[0009] Commercially grown banana plants usually have a lifespan of only 1 to 2 years, as the banana plant only flowers (and produces bananas) once, after which the leaves and pseudostems start to wither. This usually requires the leaves and pseudostems to be removed in some way, for example by cutting them off, so that new pseudostems can regenerate from the rhizomes and start a new propagation phase.

[0010] With an annual production of about 135 million tons of bananas in 2022 (more than two-thirds from India, Brazil, China, Ecuador and the Philippines), it has been recognized that the banana pseudostem is a potentially valuable renewable resource that has traditionally not been fully utilized and whose economic value has been overlooked by banana growers. As a result, there have been many attempts to use the pseudostem to produce paper, due to the favorable properties and quality of the fibers in the pseudostem.

[0011] There have been several attempts to use banana plant waste (mainly pseudostems, including leaf stalks and core, as well as leaves, immature inflorescences and unused bananas) in existing or improved papermaking pulping processes - see US patent 5958182, which briefly summarizes some of these processes. However, such waste typically contains very high moisture and natural latex content, and includes a variety of resins and sticky substances that are difficult to handle and process.

[0012] In order to produce usable fibers with the properties required for making paper, it is necessary to extract these liquids, in particular to wash out the latex and other natural resinous substances. This has proven technically difficult and has generally made banana waste pulping for paper production economically unviable, particularly for large volumes of paper supply and any use other than specialty or art paper. This has also typically presented significant chemical waste disposal problems for the producer.

[0013] In Australia, despite reports that combining banana fiber with areca nut husks (Areca catechu L.) for pulping can produce small quantities of high-quality paper, Australian researchers have concluded that extracting banana fiber from the pulping process is uneconomical due to the extremely low yield. In fact, an Australian report states that only 1 to 4 ounces (28 to 113 grams) of suitable fiber can be obtained from 40 to 80 pounds (18-36 kg) of green pseudostems during the pulping process. Therefore, 132 tons of green pseudostems can only produce 1 ton of paper. The conclusion is that processing the pseudostems into shredded organic matter left in the field and used as fertilizer for subsequent crops would be far more valuable, which is the current state of the Australian banana industry.

[0014] There are also suggestions to use banana plants without pulping, such as the mechanical processes described in the applicant's own international patent publications WO2006 / 029469 and WO2010 / 071945. The mechanical processes described in these documents aim to avoid pulping problems by first generating fiber sheets directly from the pseudostem of the banana plant, and then using these fiber sheets to form a fiber pulp, which is primarily composed of plant petiole tissue, wherein the substantially longitudinally arranged petiole fibers have been cut substantially transversely to form a fiber pulp with a fiber length distribution such that at least 95% of the fibers have substantially the same predetermined fiber length.

[0015] The present invention aims to provide an alternative method for using wood and to provide an improved method and apparatus for producing cellulose fiber materials suitable for, for example, vacuum molding to form packaging articles. Summary of the Invention

[0016] This invention provides a method for producing moldable cellulose fiber materials from cellulose fiber raw materials, the method comprising:

[0017] The raw materials are mechanically pretreated to form a fiber material with the following fiber length distribution: at least 90% of the fibers are less than about 40 mm in length;

[0018] Dehydrated fiber material is used to produce a first filtrate and a dehydrated fiber cake with a moisture content of less than about 50% (by weight);

[0019] The dehydrated fiber cake is pulped at a temperature of 45°C to 95°C to produce a pulped fiber material with a consistency of less than about 5% fiber (by weight).

[0020] Wash the pulped fiber material to produce a cellulose fiber cake with a consistency of at least 10% fiber (by weight) and a second filtrate; and

[0021] Cellulose fiber cakes are refined in at least one refining machine to produce moldable cellulose fiber materials.

[0022] The moldable cellulose fiber material produced by the method of the present invention is a material in which non-cellulose components in the raw material, such as hemicellulose, lignin, wax, tannin, and pectin, have been substantially removed by mechanical methods, preferably without the use of chemical additives. Removal of these non-cellulose components is beneficial because these components, present in the product, particularly on the surface of banana fibers, can hinder interfacial bonding between fibers.

[0023] In this respect, the moldable cellulose fiber materials produced by the method of the present invention retain the preferred physical and mechanical properties of the raw material within a relatively narrow size distribution, as described below. The method of the present invention also provides the ability to control the surface roughness of the fibers in the raw material, allowing these fibers to be customized according to different molding process requirements.

[0024] In a preferred embodiment, the method of the present invention may include a homogenization step after refining to further control the consistency of the slurry in the moldable cellulose fiber material, maintaining it between 0.5% and 10% fiber (by weight), if required by subsequent molding processes. In this embodiment, the consistency can be adjusted according to the specific molding equipment selected and the target end product properties. For example, when the intake time remains constant, a lower consistency results in less fiber being collected on the mold during the intake stage, leading to a lighter final product.

[0025] In one form, homogenization is achieved by continuously mixing the refined slurry in a slurry tank using a paddle or blade agitator. Water can be added to reduce the slurry's consistency, or further refined slurry can be added to increase its consistency.

[0026] When describing the raw materials for the method of the present invention, the raw materials are preferably banana plants of the Musaceae family. Typical banana plants within the Musaceae family include those in the genera *Musella*, *Musa*, and *Enseta*. Additionally, other plants such as members of the Zingiberales order, particularly those in the Strelitziaceae family, can also be used as raw materials for the method of the present invention. Ideally, the raw materials used in the method of the present invention should be relatively fresh, preferably harvested within approximately 10 days, the duration depending on weather and soil contamination.

[0027] While not limited to this, the following description of the invention will primarily relate to the use of banana plants with edible fruits as raw materials, such as species belonging to the Musa acuminata family (such as the well-known Cavendish and Lady Finger bananas), Musa balbisiana, or hybrids such as Musa paradisiaca (often called "plantain") and Musa sapientum.

[0028] The ideal goal of mechanical pretreatment of raw materials is to form a fibrous material in which at least 95% of the fibers are less than about 40 mm in length. Preferably, the fiber length distribution in the fibrous material should satisfy at least 95% of the fibers being less than about 30 mm in length. More preferably, the fiber length distribution in the fibrous material should satisfy at least 95% of the fibers being less than about 20 mm in length. Most preferably, the fiber length distribution in the fibrous material should satisfy at least 95% of the fibers being less than or equal to about 10 mm in length. In a preferred form, at least 98% of the fibers in the fibrous material will have substantially the same predetermined fiber length as described above.

[0029] In this regard, it has been found that controlling the fiber length in the fiber material within these preferred ranges facilitates the efficient operation of subsequent refining steps. It has also been found that controlling the fiber length in the fiber material within these preferred ranges makes subsequent molding processes of the moldable cellulose fiber material produced by the method of the present invention easier.

[0030] In one form of mechanical pretreatment, disc-shaped slices can be cut from the pseudostem to obtain substantially longitudinally arranged petiole fibers from the plant tissue. The cutting tool used can be a oscillating blade, such as a straw cutter, or a disc chipper similar to that described in the aforementioned international patent publication WO2010 / 071945, but a larger fiber production unit that is modified to receive the entire pseudostem and not just the fiber slices from the pseudostem.

[0031] For example, such an improved mechanical pretreatment device may be able to both shear pseudostems to produce leaf-like fibers with lengths less than about 15 mm, 10 mm, 5 mm, or most preferably equal to or less than 3 mm, and to make these fibers more flexible and initiate or continue the fiberization process by compressing, crushing, or impacting them. For example, such a device may utilize a chamber capable of receiving sheared fibers and simultaneously reducing their volume to compress or crush the sheared fibers, thereby producing the desired (fibrillated) fibrous material. Furthermore, by combining shearing and impact actions, fiber fragments can be produced, which are also partially dehydrated by the impact force.

[0032] In another form of mechanical pretreatment, fibers can be extracted from pseudostem tissue via a drum shredding process. In this method, the pseudostem rotates perpendicular to the rotating drum, aligned with its central axis, at a speed of approximately 500 to 1500 RPM. The drum houses two to four blades that generate a slicing motion via an anvil at the end of the feed table. Ideally, the blades will be as close to the anvil as possible to generate slicing motion without colliding with it; this distance is typically less than about 3 mm, ideally between about 0.5 and 1 mm.

[0033] In this form, to improve the consistency of fiber cutting length, a set of horizontal feed rollers can be used to control the speed of the material entering the drum, which in turn helps to control the slice length, thereby controlling the overall fiber length.

[0034] In this or other forms of mechanical pretreatment, maintaining a consistent fiber length in the fibrous material (such as a fiber length distribution of at least 90% as described above) is advantageous because all α-cellulose is contained in parallel bundles extending from the ground to the top of the plant. Maintaining and preserving this natural order during the slicing process, rather than random cutting, grinding, or milling, has been found beneficial, although not essential. This results in a more consistent fiber length and easier opening of the plant structure, which allows for the extraction of plant juice through mechanical compression alone during subsequent dehydration.

[0035] After the above mechanical pretreatment, the produced fiber material is dehydrated to produce a first filtrate and a dehydrated fiber cake with a moisture content of less than about 50% (by weight).

[0036] In one form, dehydration is preferably carried out in one or more screw presses, for example, in two passes within a single screw press, or in series of two screw presses, and can be continuous or batch processing. Ideally, more than about 50% (by weight) of the water is removed during the first pass / press, thanks to the gradual compression within the screw press and the friction between adjacent fibers and the press walls. In this form, during the second pass / press, water is ideally added to the material entering the screw press to help remove any residual impurities from the fiber surfaces, further promoting interfacial adhesion and mechanical interlocking between fibers, thus forming a dehydrated fiber cake.

[0037] In a preferred embodiment, the screw press conveys material along a perforated cylindrical screen inside a permeable cylinder via a slowly rotating Archimedean screw, preferably having a tightening pitch in which the spacing between the screw threads gradually decreases. Such a screw press is preferably inclined relative to a horizontal plane to facilitate the discharge of the first filtrate through the screen openings into a collection tank or similar facility.

[0038] During the dehydration step, regardless of the number of times the screw press is used, the preferred pressure is at least 0.5 kg / cm². However, it should be understood that, ideally, the required pressure should be determined experimentally based on different materials and plant types. This preferred method of gradual pressure increase, along with the subsequent friction between adjacent fibers and surfaces, should preferably be sufficient to separate the fibers for easy liquid extraction without weakening cell structure or losing the natural properties of the fibers. The preferred pressure range for screw press dehydration is expected to be from 0.5 kg / cm² to 2.0 kg / cm².

[0039] Ideally, in a preferred embodiment, the screen openings in the screw press comprise a series of staggered, elongated elliptical openings, preferably between 20 mm and 60 mm in length, but ideally approximately 40 mm. Each opening is fitted with a mesh configured as a series of, for example, diamond-shaped holes, composed of flexibly arranged, interlocking wires. In this embodiment, the wires are preferably elastic during operation, allowing the mesh to extend outwards during use, generally forming a concave shape. In this embodiment, as fibers pass through the screen openings, the mesh elastically extends, with the diamond-shaped gaps expanding from a width of approximately 1 mm to a width of approximately 2 to 2.5 mm.

[0040] In a preferred screw press, a gradually tightening screw pitch is ideally employed to apply mechanical stress to the material during dewatering. In this regard, it should be noted that the material entering the dewatering step can be fiber segments of substantially equal length, but varying in width and thickness. In this configuration, the gradually tightening screw pitch helps to provide constant mechanical stress, forcing the raw material to act on its own and the surface of the external screen. Subsequently, the volume of the fibers decreases as liquid is discharged through the screen gaps and the conical configuration of the screw. The continuous action of the fiber segments, the mechanical pressure, and the friction between adjacent surfaces maintain the process of extracting liquid from the raw material fibers passing through them.

[0041] The preferred geometry of the screw in the screw press ensures, as described above, relative motion between the fibers in the material and the walls of the press and screen, as well as between the fibers themselves. This interaction ideally separates the fiber bundles without reducing fiber length. This relative motion generates sufficient friction to prepare the fiber surfaces for interfacial adhesion and to remove any remaining non-cellulose compounds from the fiber surfaces. This is preferred for the preparation of dehydrated fiber cakes prior to subsequent steps and helps those steps prepare and improve the surface roughness of the fibers, increasing their surface area to maximize interfacial adhesion in the final product.

[0042] In another configuration, dewatering is preferably carried out in one or more pulverizers (e.g., one, two, or three pulverizers), ideally having a series of horizontal grooved rollers with one top and two bottom rollers through which the mechanically pretreated fibrous material passes. Preferably, the grooves of the top and bottom rollers mesh together to reduce material flow outside the target compression zone, and ideally each pulverizer has two compression zones. In this respect, ideally, one compression zone is located between the first bottom roller and the top roller, while the second compression zone is located between the top roller and the second bottom roller.

[0043] Furthermore, regarding the preferred form of the pulverizer, a fixed comb (engaging with a groove) is preferably fixed on the discharge side of each roller to scrape the dehydrated fibrous material off the roller, allowing the fibrous material to pass through the pulverizer without sticking to the roller and thus preventing recirculation. Additionally, controlling the consistency of the fibrous material flowing to the pulverizer's input rollers is advantageous, helping to ensure consistent maximum compression force, thereby maximizing the removal of the first filtrate. This also facilitates fiber bundle separation, providing initial release of colloidal material through compression force and the movement of fibers on the compression surface.

[0044] The first filtrate produced during dehydration ideally consists primarily of plant juice, the chemical composition of which is generally understood by a skilled technician, taking into account the nature and type of the raw materials used. Typically, the first filtrate contains organic acids, nutrients, and growth regulators. When banana plants are used as the raw material, the concentration of organic acids is relatively high, and the components include beneficial compounds such as gibberellins and cytokinins, as well as more common soil-amending elements such as nitrogen, phosphorus, potassium, magnesium, and calcium. As a byproduct of the method of this invention, the first filtrate is intended for use as an organic liquid fertilizer.

[0045] The dehydrated fiber cake is then pulped at a temperature of 45°C to 95°C, in one form without the addition of chemical additives, to produce a pulped fiber stock with a consistency of less than about 5% fiber (by weight). In some preferred forms, the temperature will be in the range of 45°C to 90°C, or in the range of 45°C to 85°C, or in the range of 50°C to 90°C, or in the range of 50°C to 85°C, or in the range of 60°C to 80°C. In one form, ideally, a washing tank (e.g., a hydrapulper) with an agitator will be used to mix the dehydrated fiber cake with clean water, thereby producing a pulp consistency of at least less than 5%, and ideally less than 3%.

[0046] Heating the slurry to a temperature range of 45°C to 90°C helps dissolve sugars and other undesirable components in the fiber cake and supports the release of dissolved and colloidal substances. Studies have also found that heating can improve inter-fiber bonding, thereby increasing fiber tensile strength, tear strength, and burst strength. Furthermore, heating can improve fiber distribution, reduce clumping in the final molded product, and contribute to improved sheet surface quality and thickness. Heating also increases fiber refining acceptability, thus reducing the energy input required for subsequent refining steps.

[0047] Regardless of the source and type of raw materials, after the pulping stage, ideally, the moisture content of the pulped fiber material will be greater than about 80% (by weight), preferably greater than about 85% (by weight), more preferably greater than about 90% (by weight), and most preferably greater than about 95% (by weight).

[0048] Water is preferred as the medium to remove released dissolved and colloidal substances from the heat-treated fibers. Lower consistency will improve the water's ability to remove dissolved and colloidal substances during the washing stage, but this often comes at the cost of higher energy input required for heating.

[0049] After pulping, the pulped fiber material is washed again, in some cases without the addition of chemical additives, to produce a cellulose fiber cake with a consistency of at least 10% fiber (by weight), or preferably at least 15% fiber (by weight), or more preferably at least 25% fiber (by weight), and a second filtrate.

[0050] Ideally, this washing stage involves separating the fibers from the liquid medium to remove dissolved and colloidal substances from the pulp. This is preferably achieved by passing the pulped fiber material from the pulping stage through at least one screw press (ideally the same type described above regarding dewatering) to produce a fiber cake. The fiber cake can then be added back to a washing tank equipped with an agitator, and clean water is added to reduce the consistency to at least 5% fiber (by weight).

[0051] If necessary, the washing stage can be repeated two, three, or more times to remove additional dissolved and colloidal substances. If the washing stage is repeated, the target consistency will ideally be in the range of 2% to 5% fiber (by weight). In this respect, while any additional washing will further increase the removal of dissolved and colloidal substances from the pulp, this often comes at the cost of lower pulp yield.

[0052] Through the operation and interaction of the above-described steps of the present invention, it has been found that any pulping chemicals traditionally used in papermaking, especially more toxic ones such as chlorine, hypochlorite, caustic soda, sodium sulfide, sulfurous acid, dextrin, styrene-butadiene latex, or styrene-acrylic acid, are not necessary in the dewatering, pulping, and washing stages. That said, it should be understood that using some less toxic chemicals, such as sodium bicarbonate or cationic starch, to assist in fiber preparation during the washing stage may have some benefits.

[0053] As described above, after the washing step, the cellulose fiber cake enters the refining step, which is carried out in at least one refining mill, preferably a disc mill, such as a low-consistency disc mill, in which the fibers of the cellulose fiber cake are ultimately physically modified mainly through fibrillation and roughening.

[0054] The final properties of the fiber can be directly determined by this refining process of the cellulose fiber cake. For example, if the fiber length is reduced, the strength and tear resistance of the final product will decrease, but the surface smoothness and gloss will increase, and the print quality will be better. As the degree of refining increases, density, hardness, ink retention, smoothness, and internal bond strength will increase, but thickness, compressibility, dimensional stability, and porosity will decrease. Complicating matters, initial refining increases tear resistance because the adhesion between fibers is strengthened, increasing pull-out resistance, but further refining decreases tear resistance because fiber shortening has an adverse effect on fiber strength. In other words, increased refining shortens the fiber, which enhances smoothness and printability, but reduces strength and stress resistance.

[0055] In this invention, one option is to subsequently refine the cellulose fiber cake produced during washing in a high-consistency disc mill, and then in a low-consistency disc mill, to produce a moldable cellulose fiber material. Of course, as mentioned above, refining may only need to be carried out in a single disc mill, such as a low-consistency disc mill.

[0056] The disc mill offers the flexibility to customize fiber processing, helping to meet specific refining performance indicators and ideally accommodating a range of subsequent fiber pulp molding production lines that may use the moldable cellulose fiber materials produced by this invention.

[0057] Refining energy may range from 100 kW·h / OD ton to 800 kW·h / OD ton, with the aim of reducing total refining energy while maintaining the minimum viable end-product attributes in terms of product weight, sheet thickness, surface quality, and tensile, tear, and burst strength.

[0058] Disc mills typically consist of two vertical discs with serrated or other contoured surfaces. One disc (“rotor”) rotates clockwise while the other disc (“stator”) remains stationary to provide relative rotation between them. Alternatively, two rotor discs can be used, rotating in opposite directions to provide relative rotation. Ideally, the rotor and stator have a “pattern” on one side, which may consist alternately of blades (or strips) and slits (or slots).

[0059] Cellulose fiber cake can be pumped between the discs of a disc mill, ideally through an inlet at the center of one disc. As centrifugal force pushes the fibers towards the periphery of the discs, friction between the discs causes the fibers to delaminate and internally fibrillate to the desired degree, thereby increasing tensile and burst strength, improving flexibility, and increasing the relative bonding area between fibers. The space between the discs can be widened or shortened depending on the desired degree of refining.

[0060] When discussing disc mills, the term "consistency" refers to the dry weight percentage of fibers in the suspension. Therefore, a "low-consistency" disc mill is configured to process materials with a fiber content of approximately 1% to 5%, while a high-consistency disc mill is configured to process materials with a fiber content of approximately 15% to 40%. Thus, in the form of high-consistency refining followed by low-consistency refining according to the present invention, water is added to the refined product leaving the high-consistency disc mill before it enters the low-consistency disc mill, thereby changing the water content of the product and thus altering the consistency of the product to be further refined.

[0061] In low-consistency and high-consistency disc mills, the processing side of the discs is equipped with metal refining plates covered with various protruding strips. In a preferred form, a high-consistency fiber cake is fed at a constant flow rate into the central space between two discs using a spiral or belt feeder. As the rotor rotates, the fibers move outward between the strips on the opposing discs for refining. In this configuration, the rotor may be driven by a large motor, while a smaller motor can be used to adjust the gap between the discs (opening and / or closing). In this respect, it is worth noting that low-consistency disc mills are generally more energy-efficient than high-consistency disc mills, primarily because the dry fiber content levels operated in each case differ, and because the configuration of the strips and grooves tends to be correspondingly more compact and shallower.

[0062] In addition to the method described above, the present invention also provides an apparatus for producing moldable cellulose fiber materials from cellulose fiber raw materials, the apparatus comprising:

[0063] A mechanical pretreatment device is capable of forming a fibrous material from raw materials, wherein the fibers of the fibrous material have the following fiber length distribution: at least 90% of the fibers are less than about 40 mm in length;

[0064] At least one dewatering press is used to dewater fibrous material to produce a first filtrate and a dewatered fibrous cake with a water content of less than about 50% (by weight).

[0065] A pulper is used to pulp dehydrated fiber cake at temperatures ranging from 45°C to 95°C to produce pulped fiber material with a consistency of less than about 5% fiber (by weight).

[0066] At least one dewatering press for dewatering pulped fiber material to produce a cellulose fiber cake with a consistency of at least 10% fiber (by weight) and a second filtrate; and

[0067] At least one refining machine is used to produce moldable cellulose fiber materials from cellulose fiber cakes.

[0068] The apparatus may also include at least one homogenizing tank for re-pulping and homogenizing the cellulose fiber material to produce a homogeneous cellulose fiber material for molding, having a consistency of less than about 1% fiber (by weight).

[0069] Ultimately, it needs to be recognized that the moldable cellulose fiber material produced by the refining process will then be molded and dried in an appropriate manner to the appropriate degree, depending on the output specifications of the molded product.

[0070] While not wishing to be bound by theory, it is understood that this moldable cellulose fiber material of the present invention will increase fiber length by more than about 10%, while ideally reducing fiber width by more than about 15% and fiber roughness by about 10%. It is also understood that the method of the present invention can reduce the number of fiber bends or breaks, and the softness of the fibers is often improved compared to the original raw material fibers.

[0071] Advantageously, the method of the present invention provides a lower cost process, not only because the preferred raw materials are traditionally considered waste, but also because the method utilizes simple, quick, and low-energy mechanical steps. Attached Figure Description

[0072] BRIEF DESCRIPTION OF DRAWINGS

[0073] Embodiments will now be described by way of example, with reference to exemplary apparatus that can be used to produce the above-described moldable cellulose fiber materials. However, it should be noted that the following description of the drawings and embodiments is merely an example of one way of putting the invention into practice. Therefore, the following description should not be considered as limiting the general description described above.

[0074] In the attached diagram:

[0075] Figure 1 This is a flowchart that schematically illustrates a preferred embodiment of the method of the present invention;

[0076] Figure 2(a) and 2(b) yes Figure 1 A schematic diagram of a preferred form of the screw press used in the preferred embodiment; and

[0077] Figure 3 It is used for Figure 1 A schematic diagram of a preferred form of the disc mill according to a preferred embodiment. Detailed Implementation

[0078] BRIEF DESCRIPTION OF DRAWINGS

[0079] Figure 1 The flowchart generally illustrates a preferred embodiment of the method of the present invention, which includes: mechanically pretreating banana pseudostem raw material to form a fibrous material; subjecting the fibrous material to a dehydration stage to produce a first filtrate and a dehydrated fiber cake; pulping the dehydrated fiber cake using heat and, in this embodiment, without adding any chemical additives, to produce a pulped fibrous material; washing the pulped fibrous material and, again in this embodiment, without adding any chemical additives, to produce a cellulose fiber cake and a second filtrate; and then re-pulping and refining the cellulose fiber cake in a disc mill to produce a moldable cellulose fiber material.

[0080] In this implementation, moldable cellulose fiber material is added to the recycled slurry for homogenization and coordinated with the molding and drying of the final desired product.

[0081] refer to Figure 1 The mechanical pretreatment stage shown in this embodiment is achieved by drum chipping. Although not shown, this drum chipping will be understood by those skilled in the art. In this regard, the banana pseudostem is perpendicular to the rotating drum, aligned with its central axis, and rotates at a speed of approximately 500 to 1500 RPM. In one embodiment, the drum has four blades that generate a slicing motion by passing through an anvil at the end of the feed table. The blades are brought as close as possible to the anvil to generate the slicing motion without colliding with it; this distance is between approximately 0.5 and 1.0 mm. A set of horizontal feed rollers is used to control the speed at which the material enters the drum, which in turn helps to control the slice length, and thus also the overall fiber length.

[0082] The table below (Table 1) illustrates the physical and chemical properties of the ideal fiber material prepared by mechanical pretreatment steps.

[0083]

[0084] Table 1

[0085] about Figure 1For example, the operation parameters and conditions for subsequent method steps are as follows:

[0086] Mechanical pre-treatment and dewatering

[0087] Banana plantation waste input: 6.5 tons / hour

[0088] Mechanical pretreatment and

[0089] Dehydration capacity: 6.5 tons / hour

[0090] Bio-output of dehydrated fiber: 0.16 tons / ton of waste

[0091] First (juice) filtrate output: 0.84 tons / ton of waste

[0092] Thermal treatment pulping

[0093] Pulping capacity: 11 cubic meters / hour

[0094] Biological input of dehydrated fiber: 1.04 tons / hour

[0095] Consistency: 5% by weight

[0096] Heating: 85℃

[0097] Washing and repulping

[0098] Screw press capacity: 11 cubic meters / hour

[0099] Cellulose fiber cake output: 1.82 tons / hour; Cellulose fiber cake outer diameter; Fiber content: 14% by weight; Repulping consistency: 3% by weight.

[0100] Refining

[0101] Fiber refining capacity: 9 cubic meters / hour; Fiber input for drying: 0.26 tons / hour; Input consistency: 3% by weight; Input water: 8.74 cubic meters / hour; Fiber output for drying: 0.26 tons / hour; Output consistency: 3% by weight.

[0102] Slurry homogenization

[0103] Capacity: 11 cubic meters / hour Refined slurry input: 9 cubic meters / hour Slurry input consistency: 3% by weight Input water (circulating water and clean water): 18 cubic meters / hour Output consistency: 1% by weight

[0104] Example molded product production Molded product production capacity: 10,000 pieces / hour; Drying fiber input: 0.26 tons / hour; Input consistency: 1% by weight.

[0105] Tray weight: 25 grams

[0106] Highest yield: 96%

[0107] In describing the preferred form of the apparatus, as described above, the dewatering and pulp washing processes in this embodiment are carried out continuously in two screw presses 110 arranged in series, separated by a washing tank. Due to the gradual compression within the screw presses and the friction between adjacent fibers 112 and the perforated walls 114 of the screw presses 110, the combined presses 110 remove more than about 90% (by weight) of the moisture from the fiber material—see below for details. Figure 2(a) and 2(b) Description. Before the second screw press (not shown), water is added to the material entering the second screw press in a washing tank (not shown) to help remove any residual impurities on the surface of the fibers 112, further promote interfacial adhesion and mechanical interlocking between them, and form a dehydrated fiber cake 116.

[0108] For more specific references Figure 2(a) and 2(b) In this embodiment, the screw press 110 conveys fiber material 100 in the form of fibers 112 along the inside of a perforated wall 114 in the form of a water-permeable cylindrical screen via a slowly rotating Archimedes screw 118 having a tightened pitch. The screw press 110 includes a collection tank 120 to facilitate the discharge of the first filtrate 104 through the sieve openings 130 in FIG. 2(b).

[0109] In this respect, the sieve aperture 130 comprises a series of staggered, elongated elliptical openings, each approximately 40 mm in length, and each opening is equipped with a mesh configured as a series of diamond-shaped holes, consisting of flexibly arranged, interlocking metal wires. The wires should be elastic during operation, allowing the mesh to extend outwards during use, generally forming a concave shape. In this configuration, as fibers pass through the sieve aperture 130, the mesh elastically extends, with the diamond-shaped gaps expanding from a width of approximately 1 mm to a width of approximately 2 to 2.5 mm.

[0110] During the dehydration stage, regardless of the number of cycles, the preferred pressure is at least 0.5 kg / cm². However, it should be understood that, ideally, the required pressure should be determined experimentally based on different raw materials and plant types. The preferred pressure range for the dehydration stage is expected to be from 0.5 kg / cm² to 2.0 kg / cm².

[0111] In the screw press 110, a gradually tightening screw pitch is used to apply mechanical stress to the fiber material 100 during the dewatering process. In this embodiment, the fiber material 100 entering the dewatering stage exists in the form of fiber fragments 112, which are substantially equal in length but vary in width and thickness. The gradually tightening screw pitch helps to provide constant mechanical stress, forcing the fiber fragments 112 to act on themselves, the screw 118, and the interior of the perforated wall 114. Due to liquid loss discharged through the screen openings 130, the volume of the fiber fragments 112 decreases.

[0112] The first filtrate 104 produced during the dehydration stage is primarily plant juice, the chemical composition of which is generally understood by a skilled technician, taking into account the nature and type of the raw materials used. Typically, the liquid filtrate contains organic acids, nutrients, and growth regulators. When banana plants are used as the raw material, the concentration of organic acids is relatively high, and the components include beneficial compounds such as gibberellins and cytokinins, as well as more common soil-amending elements such as nitrogen, phosphorus, potassium, magnesium, and calcium. As a byproduct of the method of this invention, the first filtrate is intended for use as an organic liquid fertilizer.

[0113] As described above, the dehydration stage produces dehydrated solids in the form of dehydrated fiber cake 116 with a moisture content of less than about 50% (by weight). However, at this stage, the physical properties of the fibers in the dehydrated fiber cake 116 are unlikely to change relative to the fiber form in the original fiber feed 100.

[0114] Back Figure 1 The flowchart shows that, after dehydration, in this embodiment, the dehydrated fiber cake 116 is pulped at a temperature ranging from 45°C to 95°C, without the addition of any chemical additives, to produce pulped fiber material. In this embodiment, pulping is carried out in a washing tank equipped with an agitator, which is a hydraulic pulper, and is mixed with clean water to make the pulp consistency less than 5% fiber (by weight).

[0115] The pulped fiber material is then washed again without the addition of any chemical additives to produce a cellulose fiber cake and a second filtrate with a consistency of at least 10% fiber (by weight). This washing stage involves separating the fibers from the liquid medium to remove dissolved and colloidal materials from the pulp, which is achieved by passing the pulped fiber material from the pulping stage through a screw press of the same type as the dewatering described above to produce a cellulose fiber cake. The pulped cellulose fiber cake is then added back to a washing tank equipped with an agitator, and clean water is added to reduce the consistency to at least 3% fiber (by weight).

[0116] The washed cellulose fiber cake then proceeds to a refining stage, a step that physically modifies the fibers of the cellulose fiber cake. In this embodiment, it has been found particularly advantageous to refine the cellulose fiber cake in a single low-consistency disc mill. However, it should be understood that any suitable number of disc mills, including one, two, three, four or more disc mills, in series or parallel, can be used to maximize or improve the refining activities that occur, or for other reasons.

[0117] Figure 3 Figure 1 An exemplary disc mill 140 is shown, comprising two vertical discs with serrated or other contoured surfaces. One disc (“rotor” 142) rotates clockwise, while the other disc (“stator” 144) remains stationary to provide relative rotation between them. The rotor 142 and stator 144 are opposite each other on their respective inner sides, each having a “pattern” of alternating blades (or strips 146) and grooves (or slots 148).

[0118] Cellulose fiber cake 102 is pumped through inlet 154 at the center of disc 142 into space 152 between two discs 142 and 144 of disc mill 140 by screw feeder 156. As centrifugal force pushes the fibers towards the periphery of discs 142 and 144, friction between the discs causes fiber delamination and internal fibrillation to the desired degree, increasing tensile and burst strength, improving flexibility, and increasing the relative bonding area between fibers. Space 152 between discs 142 and 144 can be widened or shortened depending on the desired degree of refining. The rotor 142 and screw feeder 156 are driven by a large motor 158, while a smaller motor 160 can be used to adjust (open and / or close) space 152 between discs 142 and 144.

[0119] As mentioned above, the term "consistency" refers to the percentage of dry weight of fibers in a suspension. Therefore, a "low-consistency" disc mill is configured to process materials with a fiber (by weight) content of approximately 1 to 5%, while a "high-consistency" disc mill is configured to process materials with a fiber (by weight) content of approximately 15 to 40%.

[0120] Subsequently, as described above, in this embodiment, a homogenization step is included after refining to further control the consistency of the slurry in the plastic cellulose fiber material between 0.5% and 1.0% fiber (by weight). Homogenization is achieved by continuously mixing the refined slurry in a slurry tank using a paddle mixer. Water is added as needed to reduce the slurry consistency, and further refined slurry is added to increase the slurry consistency.

[0121] Finally, it should be noted that this embodiment is merely an exemplary description, and variations and modifications within the spirit and scope of the invention are conceivable.

Claims

1. A method for producing moldable cellulose fiber materials from cellulose fiber raw materials, the method comprising: - The raw materials are mechanically pretreated to form a fiber material with the following fiber length distribution: at least 90% of the fibers are less than about 40 mm in length; - Dehydrated fiber material to produce first filtrate and dehydrated fiber cake with a moisture content of less than about 50% (by weight); - Pulping dehydrated fiber cake at temperatures between 45°C and 95°C to produce pulped fiber material with a consistency of less than about 5% fiber (by weight); - Clean the pulped fiber material to produce a cellulose fiber cake with a consistency of at least 10% fiber (by weight) and a second filtrate; as well as - Refine cellulose fiber cakes in at least one refining machine to produce moldable cellulose fiber materials.

2. The method as described in claim 1, wherein, The raw material is formed from banana plants of the Musaceae family, including the genera *Musa*, *Musa*, and *Musa*.

3. The method as described in claim 1 or 2, wherein, The mechanical pretreatment is performed by roller chipping or oscillating blade / disc chipping.

4. The method according to any one of claims 1-3, wherein, The fiber length distribution of the fiber material produced in the mechanical pretreatment step is such that at least 95% of the fiber length is less than about 30 mm, or more preferably at least 95% of the fiber length is less than about 20 mm, or most preferably at least 95% of the fiber length is less than or equal to about 10 mm.

5. The method of claim 4, wherein, At least 98% of the fibers in the fiber material have substantially the same predetermined fiber length.

6. The method according to any one of claims 1 to 5, wherein, The dehydration is carried out in one or more dehydration presses, for example, twice in one press, or in two presses connected in series, either continuously or in batches.

7. The method of claim 1, wherein, The dewatering is performed in two stages. The first stage removes more than 50% (by weight) of the moisture from the fiber material.

8. The method of claim 6 or 7, wherein, Each dewatering press is a screw press, which conveys fibrous material along a perforated cylindrical screen inside a water-permeable cylinder through a slowly rotating screw with a tightening pitch in which the spacing between the screw threads gradually decreases.

9. The method of claim 8, wherein, The dehydration pressure range of the screw press is from 0.5 kg / cm² to 2.0 kg / cm².

10. The method according to any one of claims 1 to 9, wherein the pulping temperature is in the range of 45°C to 90°C, or in the range of 45°C to 85°C, or in the range of 50°C to 90°C, or in the range of 50°C to 85°C, or in the range of 60°C to 80°C.

11. The method of any one of claims 1 to 10, wherein, The pulping is carried out in a washing tank equipped with a stirrer, such as a hydraulic pulper, and includes mixing the dehydrated fiber cake with clean water so that the pulp consistency is at least less than 5%, ideally less than 3%.

12. The method according to any one of claims 1-11, wherein, The moisture content of the pulped fiber material is greater than about 80% (by weight), preferably greater than about 85% (by weight), more preferably greater than about 90% (by weight), and most preferably greater than about 95% (by weight).

13. The method according to any one of claims 1 to 12, wherein, The pulped fiber material is cleaned by at least one dewatering press, such as a screw press.

14. The method according to any one of claims 1 to 13, wherein, The method involves finely grinding cellulose fiber cakes in a low-consistency disc mill.

15. The method of claim 14, wherein, The disc mill comprises two vertical discs with contoured surfaces, one of which rotates clockwise while the other remains stationary or rotates counterclockwise; wherein the cellulose fiber cake is pumped between the two discs through an inlet located at the center of one of the discs.

16. An apparatus for producing moldable cellulose fiber materials from cellulose fiber raw materials, the apparatus comprising: - A mechanical pretreatment device capable of forming fibrous material from raw materials, wherein the fibers of the fibrous material have the following fiber length distribution: at least 90% of the fibers are less than about 40 mm in length; - At least one dewatering press for dewatering fibrous material to produce a first filtrate and a dewatered fibrous cake with a moisture content of less than about 50% (by weight); - A pulping machine is used to pulp dehydrated fiber cake at temperatures from 45°C to 95°C to produce pulped fiber material with a consistency of less than about 5% fiber (by weight). - At least one dewatering press for dewatering pulped fiber material to produce a cellulose fiber cake with a consistency of at least 10% fiber (by weight) and a second filtrate; as well as - At least one disc mill for producing moldable cellulose fiber materials from cellulose fiber cakes.

17. A moldable cellulose fiber material produced by the method of any one of claims 1-15.

18. A packaging article made of the moldable cellulose fiber material as described in claim 17.

19. A filtrate produced by the method according to any one of claims 1-15.

20. A liquid fertilizer prepared from the filtrate as described in claim 19.

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