Process for forming moulded pulp products

Abstract

A process for forming a moulded pulp fibre product involves creating a pulp stock, providing a porous mould with pre-form mould portions, each having a forming surface that corresponds with part of the external surface of the final moulded pulp fibre product, accumulating wet refined pulp fibre on the forming surfaces of pre- form mould portions, and pressing the slurry deposit between opposing mould tool surfaces to extract liquid. Creating pulp stock involves passing a suspension of pulp fibre and liquid through a series of refining stages to refine the pulp fibre to have predetermined characteristics. Pressing the slurry deposit reduces the ratio of liquid to refined pulp fibre, and works the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

Description

[0001] Process For Forming Moulded Pulp Products

[0002] Field of the invention

[0003] The present invention relates to a process for forming moulded pulp products. The present invention also relates to a production line and production plant for forming moulded pulp products.

[0004] Background

[0005] Moulded pulp fibre is well known for use in packaging products (such as egg cartons, box inserts, and the like), single use food and beverage service trays I containers, and transport products. Moulded pulp fibre products have the benefit over many equivalent plastics materials that they can be composted after the product's useful life.

[0006] A widely utilized process (hereinafter referred to as the "basic process") for forming moulded pulp fibre products involves:

[0007] 1. creating a pulp stock, being a suspension of pulp fibre and liquid;

[0008] 2. immersing a forming head into the pulp stock, the forming head having a shaped mesh mould;

[0009] 3. applying suction to the forming head, so as to draw the pulp fibre onto the mesh mould, whereby a pre-form (which may be considered a "slurry deposit"; in other words, a combination of liquid and the pulp fibre that forms the final moulded pulp fibre product) is formed on the mesh mould;

[0010] 4. removing the forming head from the open tank, while maintaining a suction pressure to hold the pre-form on the mesh mould; and

[0011] 5. drying the pre-form to consolidate the pulp fibre material.

[0012] The drying step of the basic process typically involves baking the pre-form in a dryer oven to fix the bonds between the structure, such that the final product has the desired structural integrity. A modified process for forming moulded pulp fibre products is known as "thermoforming", or "precision moulding". This process utilizes a toolset of two (or more) complementary moulds that are heated, and compress the wet pulp pre-form during the drying step. This process has the benefit of forming products with thinner walls, greater structural integrity, and smoother surface finishes, compared with the basic process.

[0013] Typically, a production plant for moulded pulp fibre products receives pulp material from a pulping mill, for example in a dried sheet form. The pulp material that is produced by the pulping mill is considered to be raw pulp fibre. At the production plant, the raw pulp fibre material is macerated in a repulper to prepare a pulp stock. Within the repulper, the raw pulp fibre is at least partially disintegrated and mixed with water to form a pumpable suspension (typically with a fibre content of the order of 4%, or less), which is the pulp stock. A pulp stock that has nonuniform and / or heterogenous fibre material in the pulp stock results in a final pulp product with inconsistent properties / characteristics. To make the pulp stock more uniform and homogeneous, the partially disintegrated pulp in suspension from the repulper can be deflaked to further disintegrate large particles in the pulp. In this part of the process the size and number of fibre bundles, shives and flakes is reduced.

[0014] The structural and physical characteristics of the fibrous material in the pulp stock can be altered by refining operations, which involve mechanical work on the pulp fibre. Refining is performed on the pulp stock with the aim of tailoring the characteristics of the pulp fibre to result in desired properties of the final product. The characteristics altered during refining include (but are not limited to) the fines content, shives content, fibrillation, fibre hydration (which affects fibre flexibility), fibre length, fibre curl I kink. Pulp fibre refining is used in the production of paper and paper-board products to increase the density of the fibre network in the final product, which affects the elastic modulus and tensile strength in the final product.

[0015] Pulp fibre refining action consumes vast amounts of energy, which comes at a cost.

[0016] Further, there is a decrease in the rate at which water is drained from and through the pulp fibre as the refining level increases. Hence, the effort (in other words, energy) required to drain water initially from the suspension to create the slurry deposit, and then to further dry the pulp fibre increases with the level of refining. As a result of the increased energy that comes with increased refining of pulp fibre in the pulp stock, the aim is to minimize the extent of refining, having regard to the properties required in the final product.

[0017] Although moulded pulp products and paper products use substantially similar raw material fibres, the forming processes (including material fibre processing) are dramatically different. One significant difference is that moulded pulp products are essentially formed individually (either wholly, or within batch operations on a set of products), whereas paper can be formed in continuous production processes. The continuous production processes used for paper and paperboard manufacture can accommodate increases in de-watering time (being the drainage and evaporation rates) through the use of process equipment (such as dewatering hydrofoils, multiple press nips, and the like) that are feasible in a continuous production processes. The "direction" of de-watering in paper and paperboard forming processes is generally perpendicular to the machine direction (the major planes of the paper sheet), which means that pressing operations are highly efficient.

[0018] In contrast, the forming processes for (typically three-dimensional) moulded pulp fibre products encounter dramatic challenges with increasing levels of pulp fibre refining. To this end, the batch-type nature of moulded pulp fibre product forming means that the production rates of these products decreases very quickly with the increasing levels of fibre refining. This issue is exacerbated further in thermoforming processes where draft angles in the final moulded pulp product approach the tool set closure direction, where the dewatering "direction" approaches parallel to the major surfaces of the product, and the material is subjected to shear in the de-watering process.

[0019] Studies have shown that de-watering time is directly linked to commercial viability (Debnath et al., 2022, "Molded pulp packaging review", BioResources 17(2), 3810-3870). Hence, the many benefits that pulp refining can provide to paper and paperboard products, noted above, do not translate to moulded pulp fibre products in the commercial environment. For moulded pulp fibre products, the barriers encountered with increasing levels of fibre refinement have placed limitations on the forming processes, and consequently on the functional and structural characteristics in the final products. In turn, these characteristic limitations have led to limitations on the range of products that are produced from moulded pulp fibre, as noted above.

[0020] It is widely accepted that in commercial-scale production of moulded pulp fibre products, processing of pulp fibre to form the pulp stock only involves low levels of fibre refining.

[0021] There is a need to address the above, and / or at least provide a useful alternative.

[0022] For the purposes of this specification, and the claims that follow, references to "draining" and "drainage" of liquid from a suspension are to be understood to include scenarios in which liquid is removed from the suspension by gravity alone, by application of vacuum, and by application of pressurised gases. The latter two scenarios can be acting to remove liquid with, or against gravitational drainage.

[0023] For the purpose of this specification and the claims that follow, a "fibre" is to be understood as referring to fibrous material that has a length that is greater than or equal to 200 / zm. The terms "fine" and "fines", in the context of pulped fibrous material, are to be understood as referring to fibrous material that has a length that is less than 200 / zm, and is at least approximately 2 zm or greater in any direction. Fibrous material that is smaller than a fine is considered to be cellulosic microparticles. The phrase "proportion of fines by length of the suspension" is to define the total length of all fines as a percentage of the total length of all fibres in the suspension. By way of example, a determination of the proportion of fines by length of a suspension can be made on the basis of morphological analysis undertaken on one or more samples of that suspension.

[0024] For the purposes of this specification and the claims that follow, references to "pulp fibre" (including "raw pulp fibre", "partially refined pulp fibre", and "refined pulp fibre") are to be understood as including pulped fibrous material that includes fibres, and may also include fines.

[0025] Summary

[0026] There is provided a process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving: forming a suspension of pulp fibre and liquid, and passing the suspension through a series of refining stages that each refine the pulp fibre, whereby the refined pulp fibre within the pulp stock has a mean fibre length that is less than the mean length of the raw pulp fibre from which the suspension is created, and has a proportion of fines by length in the pulp fibre component of the suspension that is at least 45%; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet refined pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated refined pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to refined pulp fibre, and working the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

[0027] In at least some embodiments, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is 90% or greater of the mean raw fibre width. Preferably, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is 95% or greater of the mean raw fibre width. Even more preferably, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is substantially unchanged from the mean raw fibre width.

[0028] There is provided a process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving: forming a suspension of pulp fibre and liquid, and passing the suspension through a series of refining stages that each refine the pulp fibre, whereby the refined pulp fibre within the pulp stock has a mean fibre length that is less than the mean length of the raw pulp fibre from which the suspension is created, and the refined pulp fibre within the pulp stock has a mean fibre width that is 90% or greater of the mean raw fibre width; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet refined pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated refined pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to refined pulp fibre, and working the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

[0029] In at least some embodiments, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is 95% or greater of the mean raw fibre width. Preferably, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is substantially unchanged from the mean raw fibre width. In at least some embodiments, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a proportion of fines by length in the pulp fibre component of the suspension that is at least 45%.

[0030] In at least some embodiments, pressing the slurry deposit between opposing mould tool surfaces includes a series of two or more pressing stages that are configured to progressively extract liquid from the slurry deposit, wherein the geometry of the accumulated refined pulp fibre changes from the initial slurry deposit form into the final moulded pulp fibre product form with progression through the series of pressing stages.

[0031] In certain examples, the change in geometry of the accumulated refined pulp fibre from the initial slurry deposit form into the final moulded pulp fibre product form includes one or more intermediate forms that are formed by a respective one of the series of pressing stages prior to the final pressing stage.

[0032] In some examples, the geometry change of the accumulated refined pulp fibre at each pressing stage can be any one or more of: a reduction in the thickness of part(s) or the entirety of the accumulated refined pulp fibre; a change in the geometric proportions of the accumulated refined pulp fibre; or a relative displacement of two spaced apart surface portions of the accumulated refined pulp fibre.

[0033] Preferably, the proportion of fines by length in the pulp fibre component of the suspension is between 50% and 60%. Even more preferably, the proportion of fines by length in the pulp fibre component of the suspension is approximately 55%.

[0034] Alternatively or additionally, creating the pulp stock involves refining the pulp fibre to a Canadian Standard Freeness of less than approximately 300 mL CSF. There is provided a process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving: forming a suspension of pulp fibre and liquid, and passing the suspension through a series of refining stages that each refine the pulp fibre, such that the pulp stock has a Canadian Standard Freeness of less than approximately 300 mL CSF; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet refined pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated refined pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to refined pulp fibre, and working the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

[0035] In certain embodiments, creating the pulp stock involves refining the pulp fibre to a Canadian Standard Freeness of 100 to 200 mL CSF. Preferably, creating the pulp stock involves refining the pulp fibre to a Canadian Standard Freeness of 100 to 150 mL CSF. Even more preferably, creating the pulp stock involves refining the pulp fibre to a Canadian Standard Freeness of approximately 130 mL CSF.

[0036] In some examples, each refining stage involves passing the suspension through at least one refiner that has a rotor and stator defining a gap therebetween through which to pass the suspension, wherein the series of refining stages is arranged such that the width of the gap is reduced between at least some consecutive stages in the series.

[0037] In certain embodiments, the series of refining stages includes an initial refining stage, and one or more subsequent refining stages, and the process includes setting the width of the gap between the rotor and stator prior to passing the suspension through each of the subsequent refining stages.

[0038] Setting the width of the gap prior to passing the suspension through each of the subsequent refining stages can be made:

[0039] - in accordance with a predetermined protocol, and / or

[0040] - based on analysis of the partially refined pulp in the suspension to target predetermined suspension characteristics at the completion of the respective subsequent refining stage.

[0041] In some instances, setting the width of the gap involves reducing the width of the gap between the rotor and stator, compared with the width of the gap of the immediately preceding refining stage. In some instances, setting the width of the gap involves maintaining the same width of the gap as used in the immediately preceding refining stage. In some instances, setting the width of the gap involves increasing the width of the gap between the rotor and stator, compared with the width of the gap of the immediately preceding refining stage.

[0042] In some examples, each refining stage involves passing the suspension through a refiner that has a rotor and stator defining a gap therebetween through which to pass the suspension, and wherein passing the suspension through a series of refining stages involves circulating the suspension, with each refining stage corresponding with passing the suspension through the gap.

[0043] Circulating the suspension can involve continuous flow of suspension, such that at any one time a portion of the suspension is passing through gap, while another portion of the suspension is progressing along a flow path that extends from an outlet of the gap to an inlet of the gap.

[0044] The pulp fibre from which the pulp stock is created can be bagasse. In some examples, creating the pulp stock involves refining the pulp fibre such that within the refined pulp stock the mean pulp fibre length is less than or equal to 1 millimetre. In some preferred examples, creating the pulp stock involves refining the refined pulp fibre such that within the pulp stock the mean pulp fibre length is within the range of 0.58 millimetres to 1 millimetre.

[0045] In some examples, creating the pulp stock involves refining the pulp fibre such that within the pulp stock the mean length of the refined pulp fibre is less than or equal to 1 millimetre. In some preferred examples, creating the pulp stock involves refining the pulp fibre such that within the pulp stock the mean length of the refined pulp fibre is within the range of 0.58 millimetres to 1 millimetre. In some instances, creating the pulp stock involves refining the pulp fibre such that within the pulp stock the mean length of the refined pulp fibre is 0.7 millimetres ± 0.1 millimetres.

[0046] In some alternative or additional embodiments, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width is within the range of 15 to 25 / / m. In some instances, creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width is 25 / m ± 5 / / m.

[0047] In some examples, creating the pulp stock further involves refining the pulp fibre such that the proportion of the fines in the pulp stock that are secondary fines is less than one third. In certain applications, creating the pulp stock further involves refining the pulp fibre such that the proportion of the fines in the pulp stock that are secondary fines is less than approximately 25%.

[0048] In certain embodiments, creating the pulp stock further involves refining the pulp fibre such that the shives content measured by imaging techniques constitutes a fibrous area that is less than 0.5%. In some instances, creating the pulp stock further involves refining the pulp fibre such that the shives content measured by imaging techniques constitutes a fibrous area that is approximately 0.3%.

[0049] In some examples, creating the pulp stock further involves refining the pulp fibre such that the refined pulp fibre within the pulp stock has a fibrillation index that is at least 1%. Alternatively or additionally, the refined pulp fibre within the pulp stock has a fibrillation index that is between 1.5% and 2%. In some examples, the refined pulp fibre within the pulp stock has a fibrillation index that is approximately 1.8%.

[0050] In some examples, creating the pulp stock further involves refining the pulp fibre such that the pulp stock has a fines content that is less than or equal to 65% in length. Alternatively or additionally, the pulp stock has a fines content that is between 50% and 60% in length. In some examples, the pulp stock has a fines content of approximately 55% in length. The fines content is determined by total fines length as a fraction (percentage) of total fibre length within a sample.

[0051] The series of refining stages can comprise two or more refining stages that each have a predetermined gap width, wherein each of the second and subsequent refining stages has a gap width that is within the range of 40% to 95% of the gap width in the immediately preceding refining stage.

[0052] Forming the suspension of pulp fibre and liquid can further involve macerating raw pulp fibre in the liquid.

[0053] Creating the pulp stock can additionally involve passing the suspension through a deflaking stage. Preferably, the suspension is passed through the deflaking stage prior to the refining stages. A reduction in the thickness of part(s) of the slurry deposit in any one of the pressing stages can involve: a reduction in a direction that is parallel to the relative movement of the opposing mould tool surfaces; in directions that are transverse to the relative movement of the opposing mould tool surfaces; or in directions that are parallel and transverse to the relative movement of the opposing mould tool surfaces.

[0054] Preferably, each of the pressing stages involves reducing the thickness of the slurry deposit in any one direction by less than or equal to 50%.

[0055] In some embodiments in which the series of pressing stages includes three or more pressing stages, at least one of the pressing stages involves reducing the thickness of the slurry deposit only in the direction that is parallel to the relative movement of the opposing mould tool surfaces.

[0056] In certain embodiments, in the first of the series of pressing stages, the forming surfaces of the pre-form mould portion is one of the opposing mould tool surfaces.

[0057] Preferably, in at least some of the pressing stages, the mould tools defining the opposing mould tool surfaces are heated, and the process further involves controlling the temperature of the respective opposing mould tool surfaces, such that at the conclusion of the respective pressing stage the ratio of refined pulp fibre to liquid has a predefined value.

[0058] Alternatively or additionally, in at least some of the pressing stages, the mould tools defining the opposing mould tool surfaces have extraction paths that are in communication with a vacuum source, and the process further involves controlling the suction force applied to the extraction paths, such that at the conclusion of the respective pressing stage the ratio of refined pulp fibre to liquid has a predefined value. There is also provided a process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving forming a suspension of pulp fibre and liquid; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to pulp fibre, and working the pulp fibre from the slurry deposit form into the final moulded pulp fibre product form, wherein the geometry of the accumulated pulp fibre changes from the initial slurry deposit form into the final moulded pulp fibre product form with progression through the series of pressing stages.

[0059] In some examples, the geometry change of the accumulated pulp fibre at each pressing stage can be any one or more of: a reduction in the thickness of part(s) or the entirety of the accumulated pulp fibre; the geometric proportions of the accumulated pulp fibre; or a relative displacement of two spaced apart surface portions of the accumulated pulp fibre.

[0060] A reduction in the thickness of part(s) of the slurry deposit in any one of the pressing stages can involve: a reduction in a direction that is parallel to the relative movement of the opposing mould tool surfaces; in directions that are transverse to the relative movement of the opposing mould tool surfaces; or in directions that are parallel and transverse to the relative movement of the opposing mould tool surfaces. Preferably, each of the pressing stages involves reducing the thickness of the slurry deposit in any one direction by less than or equal to 50%.

[0061] In some embodiments in which the series of pressing stages includes three or more pressing stages, at least one of the pressing stages involves reducing the thickness of the slurry deposit only in the direction that is parallel to the relative movement of the opposing mould tool surfaces.

[0062] In certain embodiments, in the first of the series of pressing stages, the forming surfaces of the pre-form mould portion is one of the opposing mould tool surfaces.

[0063] Preferably, in at least some of the pressing stages, the mould tools defining the opposing mould tool surfaces are heated, and the process further involves controlling the temperature of the respective opposing mould tool surfaces, such that at the conclusion of the respective pressing stage the ratio of pulp fibre to liquid has a predefined value.

[0064] Alternatively or additionally, in at least some of the pressing stages, the mould tools defining the opposing mould tool surfaces have extraction paths that are in communication with a vacuum source, and the process further involves controlling the suction force applied to the extraction paths, such that at the conclusion of the respective pressing stage the ratio of pulp fibre to liquid has a predefined value.

[0065] Brief description of the drawings

[0066] In order that the invention may be more easily understood, embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0067] Figure 1: is a flow chart of a process for forming a moulded pulp fibre product, the process being in accordance with a first embodiment;

[0068] Figure 2: is a flow chart showing further detail of refining operation(s) of the process illustrated in Figure 1; Figure 3: is a flow chart showing further detail of the pressing operation of the process illustrated in in Figure 1;

[0069] Figures 4a and 4b: are a schematic process flow diagram showing equipment, operation, and stages in an implementation of the process for forming a moulded pulp fibre product illustrated in Figures 1 to 3;

[0070] Figures 5a to 5f: are schematic cross sectional views showing the material deformation in each of the pressing stages shown in Figure 4b; and

[0071] Figure 6: is a flow chart of a process for forming a moulded pulp fibre product, the process being in accordance with a second embodiment.

[0072] Detailed description

[0073] Figure 1 is a flow chart showing operations in a process 100 for forming a moulded pulp fibre product. The process 100 involves:

[0074] Operation 102 - Creating a pulp stock, that includes refined pulp fibre and liquid;

[0075] Operation 120 - Providing a porous mould having one or more pre-form mould portions that each has a forming surface;

[0076] Operation 122 - Accumulating wet refined pulp fibre on the forming surfaces; and

[0077] Operation 124 - Pressing the slurry deposit between opposing mould tool surfaces to extract liquid.

[0078] Figure 2 illustrates the operation of creating the pulp stock (Operation 102) in further detail. Operation 102 more particularly involves:

[0079] Operation 104 - Forming a suspension of the pulp fibre and the liquid; and

[0080] Operation 108 - Passing the suspension through a series of refining stages. Figure 3 illustrates pressing the slurry deposit between opposing mould tool surfaces to extract liquid (Operation 124) in further detail.

[0081] The raw materials for the pulp fibre can be any desired cellulose material, which may be derived from plants. To this end, the raw pulp fibre material can be plant fibres from a pulping mill that are supplied as sheets of dried pulp fibre. The suspension formed at Operation 104 can then be obtained by combining the sheets of dried pulp fibre with a liquid (such as water). It may be necessary to disintegrate the pulp fibre by a maceration action.

[0082] At Operation 108, the suspension is passed through a series of refining stages that each refine the pulp fibre. The refined pulp fibre within the pulp stock has:

[0083] - a mean fibre length that is less than the mean length of the raw pulp fibre from which the suspension is created, and

[0084] - a proportion of fines by length in the pulp fibre component of the suspension that is between 45% and 65%.

[0085] The mean fibre length can be determined by morphological analysis techniques I instruments. The proportion of fines by length can also be determined by morphological analysis techniques I instruments. This is discussed in further detail below.

[0086] As shown in Figure 2, the suspension formed in Operation 104 may be subjected to a deflaking Operation 106. As is known, deflaking the suspension separates bundles of fibres (which are known as shives). During deflaking, the pulp fibre material is subjected to a grinding-like action that induces a shear on the pulp fibre. The shear commences separation of the shives, with minimal alteration on the properties of the individual fibres. This Operation 106 can reduce the energy required in the refining stages.

[0087] In the example illustrated in Figure 2, there are four refining stages (identified as Operations 110, 112, 114, 116) in the series. The equipment used to effect Operation 108 influences aspects of the process 100. The flow chart as illustrated in Figures 1 and 2 illustrates the example in which each refining stage Operations 110, 112, 114, 116 involves passing the suspension through a common refiner that has a rotor and stator defining a gap therebetween through which to pass the suspension. The refiner is configured to allow the gap width between the rotor and stator to be adjusted. Further, the deflaking Operation 106 is effected by passing the suspension through the refiner.

[0088] The gap width of the refiner is set to an initial gap width prior to the deflaking Operation 106. After the deflaking Operation 106, the process 100 involves setting the rotor / stator gap width at Operation 106b to the width required for the 1stpulp fibre refinement Operation 110. Similarly, after each of the 1st, 2nd, and 3rdrefining stages 110, 112, 114, the process 100 involves setting the rotor / stator gap width at Operations 110b, 112b, 114b to the width required for the respective subsequent pulp fibre refinement operation. In Operations 110b, 112b, 114b, the gap width is set such that the pulp fibre is progressively worked through Operation 108 to the target level of refinement.

[0089] The process 100 includes an optional Operation 114c, in which the suspension following Operation 114 ("3rdpulp fibre refinement") is analysed to assess the properties of the partially refined pulp fibre in the suspension. The analysis may be an empirical measure that is representative of the properties of the partially refined pulp fibre (such as the Canadian Standard Freeness), and / or quantitative measurements of the actual partially refined pulp fibre (such as by morphological analysis). This analysis provides a refining progress indicator of the extent of refining that has been effected in the 1st, 2nd, and 3rdrefining stages 110, 112, 114.

[0090] The analysis and assessment of the refining level of the partially refined pulp fibre at the conclusion of Operation 114 provides a refining progress indicator, with which the gap width of the rotor and stator in the refiner can be set for the final refining stage 116; hence, the pulp stock is refined to a level that is close to, or (ideally) at the target level of refinement in the pulp stock. Depending on the analysis in Operation 114c, Operation 114b can involve any of reducing the gap width, maintaining the gap width used in the 3rdpulp refinement Operation 116. The analysis and assessment of the refining level of the partially refined pulp fibre to provide a refining progress indicator may be performed after the 1stor 2ndrefining stages 110, 112. This may be conducted as an alternative or supplement to Operation 114c as described above. Further, the gap width for one or more of the subsequent refining stages can be set based on the refining progress indicator.

[0091] In some alternatives, the process 100 may not require an analysis of the suspension prior to the 4threfining stage 116. In these alternatives, the gap width at each refining stage is set according to a protocol.

[0092] After the 4thpulp fibre refinement Operation 116, the pulp stock is prepared for use. As shown in Figure 2, the pulp stock is the transferred 118 as required for the accumulation Operation 122.

[0093] As shown in Figure 3, Operation 124 broadly involves a series of two or more pressing stages that are configured to progressively extract liquid from the slurry deposit. In the example illustrated in Figure 3, there are five pressing stages (identified as Operations 126, 128, 130, 132, 134). As the slurry deposit progresses through the series of pressing stages, the geometry of the accumulated refined pulp fibre changes from the initial slurry deposit form into the final moulded pulp fibre product form. As each of the five pressing stages in this example (Operations 126, 128, 130, 132, 134) uses separate mould tools to provide the opposing mould tool surfaces at each pressing stage, the accumulated refined pulp fibre is transferred on four occasions - see Operations 126b, 128b, 130b, 132b ("Transfer pre-form") in Figure 3 - between consecutive press stages. The geometry change of the accumulated refined pulp fibre at each pressing stage is at least partially dictated by the shapes of the opposing mould tool surfaces of the respective pressing stage. The geometry change at each stage can involve any one or more of:

[0094] - a reduction in the thickness of part(s) or the entirety of the accumulated refined pulp fibre;

[0095] - the geometric proportions of the accumulated refined pulp fibre; or

[0096] - a relative displacement of two spaced apart surface portions of the accumulated refined pulp fibre.

[0097] These changes are discussed in further detail below.

[0098] It will be understood by those skilled in the art from this disclosure that the processes disclosed herein are able to form moulded pulp fibre products that have desirable characteristics, including (but not limited to) high material densities (notably in wall sections that have draft angles in the range of 10° to 5°), high geometric tolerances, material surface characteristics (such as surface roughness), mechanical characteristics, and water vapour transmission and / or oxygen transmission resistance I barrier properties.

[0099] With respect to the resistance / barrier properties, moulded pulp fibre products can be formed in which the moulded pulp fibre material alone provides at least resistance, if not a level of barrier, to water vapour transmission, and / or oxygen transmission that is comparable with so-called "moderate" barrier plastics (for example, some PVCs and PETs). These, and other characteristics, of moulded pulp fibre materials formed in accordance with processes disclosed herein are discussed in further detail below.

[0100] It is further notable that processes disclosed herein that include multiple pressing operations on the accumulated pulp fibre can provide a level of control in the forming process that enables the formation of moulded pulp fibre products that, in addition to one or more of the above described material characteristics, have complex geometries. In this regard and in the context of moulded pulp fibre products, the term "complex geometries" is to be understood to include any one or more of: - low draft angles (in other words, surfaces of the moulded pulp fibre product having a low angle relative to the mould tool pressing direction; for example, example less than 7°,

[0101] - concave and convex corners with small I tight radii, and

[0102] - products in which the side wall "height" is greater than the lateral I diametric separation of the side walls.

[0103] It will be appreciated that the above list is not exhaustive.

[0104] Each of pressing stages 126, 128, 130, 132, 134 can be individually controlled in respect of the press load (including maximum compression force and load profile), mould tool temperature, and press time. Some of the press stages can also use suction to aid in extracting liquid from the refined pulp fibre material, and in each of these stages, the suction force can also be individually controlled. The work that each press stage performs on the accumulated refined pulp fibre can be tailored, having regard to liquid content of the material at the commencement of the pressing stage. In this regard, it is relevant to note that the liquid content of pulp fibre materials is a significant factor in the strength of the material due by virtue of the extent of hydrogen bonds, particularly between individual fibres in the material.

[0105] Accumulating wet pulp fibre on the forming surfaces (Operation 122) involves progressing the pulp stock (created in Operation 102) towards the porous mould and removing some of the liquid component of the suspension through the porous mould. In this way, pulp fibre component of the suspension accumulates on the forming surface to form a slurry deposit; hence, the slurry deposit includes liquid, and at least fibres and fines from the suspension. The liquid content of the slurry deposit (being liquid to accumulated refined pulp fibre fraction at the conclusion of Operation 122) is dependent on many factors. In one example, Operation 122 may be operated to target a liquid content in the accumulated refined pulp fibre that is in the range of 80% to 90% by weight. In this state, the accumulated refined pulp fibre in the slurry deposit is particularly soft, such that the slurry deposit is unable to self-support. Referring again to the example of Figure 3, Operation 124 involves:

[0106] Operation 126 - "Press on porous mould": the forming surfaces of the porous mould provide one of the two opposing mould tool surfaces. The slurry deposit is pressed between the forming surfaces, and a mould tool surface of a heated mould tool.

[0107] Using the porous mould in the first of the pressing stages has the benefit that the porous mould provides structurally support to the slurry deposit from accumulation (Operation 122) and the first pressing stage (Operation 126).

[0108] At the conclusion of Operation 126, the form of the accumulated refined pulp fibre has altered, and the liquid content of the material has been reduced (compared with that of the slurry deposit). Hence, the article may be considered to be a pre-form (in other words, a partially formed version of the final moulded pulp fibre product).

[0109] In one example, Operation 126 may be operated to target a liquid content in the pre-form at the conclusion of Operation 126 in the range of 70% to 87% by weight. Hence, the reduction in the liquid content in the pre-form is of the order of 3% to 10%.

[0110] Operation 128 - "1st pre-form press": the pre-form - having been transferred in Operation 126b - is pressed between two opposing mould tool surfaces of a first press mould tool set.

[0111] In one example, Operation 128 may be operated to target a liquid content in the pre-form at the conclusion of Operation 128 in the range of 55% to 82% by weight. Hence, the reduction in the liquid content in the pre-form is of the order of 5% to 15%.

[0112] Operation 130 - "2nd pre-form press": the pre-form - having been transferred in Operation 128b from the first press mould tool set - is pressed between two opposing mould tool surfaces of a second press mould tool set.

[0113] In one example, Operation 130 may be operated to target a liquid content in the pre-form at the conclusion of Operation 130 in the range of 35% to 67% by weight. Hence, the reduction in the liquid content in the pre-form is of the order of 15% to 35%.

[0114] Operation 132 - "3rd pre-form press": the pre-form - having been transferred in Operation 130b from the second press mould tool set - is pressed between two opposing mould tool surfaces of a third press mould tool set.

[0115] In one example, Operation 132 may be operated to target a liquid content in the pre-form at the conclusion of Operation 130 in the range of 0% to 10% by weight. Hence, the reduction in the liquid content in the pre-form is of the order of 32% to 67%.

[0116] In this stage, the pre-form is substantially dry.

[0117] Operation 134 - "4th pre-form press": the pre-form - having been transferred in Operation 132b from the second press mould tool set - is pressed between two opposing mould tool surfaces of a third press mould tool set.

[0118] Operation 134 can be employed in the process 100 with the intention of making structural changes to the pulp fibre network within the material of the pre-form. To this end, the structural changes can include consolidating bonds internally within the pulp fibre material, hardening and / or smoothing surfaces of the pulp fibre material, and closing up residual pores within the pulp fibre material by final compression.

[0119] At the conclusion of Operation 134, the moulded pulp fibre product is formed, subject to any secondary processing operations, such as material trimming, and application of surface coatings, adornment, or the like.

[0120] Accumulating wet pulp fibre on the forming surfaces (Operation 122) involves progressing the pulp stock (created in Operation 102) towards the porous mould and removing some of the liquid component of the suspension through the porous mould. In this way, pulp fibre component of the suspension is accumulated on the forming surface, to form a slurry deposit.

[0121] The nature of the accumulation operation will be at least partly dependent on the construction of the plant equipment in an implementation of the process 100. In some examples, the porous mould is brought onto the surface of a reservoir of the suspension. The porous mould is connected to a vacuum source, and suction pulls liquid component of the suspension towards and through the porous mould. The movement of the liquid component carries pulp fibre component towards the porous mould, leading to accumulation of pulp fibre on the forming surface.

[0122] In some alternative examples, the porous mould closes the base of a hopper, with the forming surface facing into the chamber of the hopper. A charge of the suspension is loaded into a hopper. The liquid component of the suspension is drained and / or pulled through the porous mould to thereby accumulate the pulp fibre component of the suspension on the forming surface, so as to form the slurry deposit.

[0123] Figures 4a and 4b illustrate schematically a process flow diagram for a production line 200 of an implementation of the process 100. The process flow diagram illustrates schematically plant equipment of an embodiment that is implement parts of the process 100.

[0124] As shown in Figure 4a, raw pulp fibre ("RPF") and water (H2O) is loaded into a repulper 202. The repulper 202 has a set of blades that macerate the raw pulp fibre. Once the raw pulp fibre has been sufficiently disintegrated to create the desired suspension of pulp fibre in water, the suspension is pumped to a first holding tank 204 via flow line 206. The production line 200 also includes a second holding tank 208, a refiner 210. The first holding tank 204, second holding tank 208 and refiner 210 are interconnected by flow line 212 to the inlet of the refiner 210, and to the outlet of the refiner 210 via flow line 214. A set of pumps and valves (not shown) control the flow of the suspension between first holding tank 204, refiner 210 and second holding tank 208. Essentially, the suspension is passed back and forward between the first and second holding tanks 204, 210 and through the refiner 210 for each of the deflaking Operation 106, and the series of refining Operations 108.

[0125] Once the pulp stock is prepared, the pulp stock is transferred (Operation 118) to a third holding tank 216 via a flow line 218 that branches off flow line 214.

[0126] The production line 200 includes a make-up tank 220 that receives the pulp stock via flow line 222. The make-up tank 220 is connected with a reservoir, which in this example is a pulp stock pond 224. As shown in Figure 4a, the make-up tank 220 can have a water inlet to allow the pulp stock to be diluted if desired prior to discharge to the pulp stock pond 224. Any additives for the pulp stock can be added, directly into the make-up tank 220 (as indicated by item AA), and / or into the flow line 222 between the make-up tank 220 and the pulp stock pond 224 (as indicated by item Ay).

[0127] In the example of Figure 4a, the porous mould 226 is oriented with the forming surface 228 facing in a generally downward direction. The porous mould 226 is lowered into the pulp stock in the pulp stock pond 224. A vacuum line (not shown) that is connected to the porous mould 226 is operated to accumulate refined pulp fibre within the pulp stock on the forming surface 228 as described previously.

[0128] Figure 4b illustrates the series of pressing stages (Operation 124). These pressing stages are implemented on equipment of the production line 200 of this embodiment, as follows:

[0129] - a complementary mould tool 230 that has a mould surface that is complementary of, and hence cooperates with, the porous mould 226 - for Operation 126 ("Press on porous mould");

[0130] - a first press mould tool set 232 that includes a first lower mould tool 234 and a first upper mould tool 236 for Operation 128 ("1stpre-form press");

[0131] - a second press mould tool set 242 that includes a second lower mould tool 244 and a second upper mould tool 246 for Operation 130 ("2ndpre-form press");

[0132] - a third press mould tool set 252 that includes a third lower mould tool 254 and a third upper mould tool 256 for Operation 132 ("3rdpre-form press"); and

[0133] - a fourth press mould tool set 262 that includes a fourth lower mould tool 264 and a fourth upper mould tool 266 for Operation 134 ("4thpre-form press").

[0134] The production line 200 includes transfer equipment (not shown) to transfer the pre-form sequentially from the porous mould 226, and onto the first, second, third and fourth lower mould tools 234, 244, 254, 264. In one example, the first, second, third and fourth upper mould tools 236, 246, 256, 266 reciprocate to close the respective tool set, and effect each of the pressing stage Operations 128, 130, 132, 134, 136.

[0135] The complementary mould tool 230 can include heating elements (not shown) to facilitate heat transfer to the slurry deposit during Operation 126. If desired, suction can be applied during Operation 126 via the vacuum line to extract liquid from the slurry deposit. Similarly, one or both mould tools in at least some of the first, second, third and fourth mould tool sets 232, 242, 252, 262 can include heating elements (not shown) to facilitate heat transfer to the pre-form during the respective pressing Operation 128, 130, 132, 134.

[0136] Vacuum lines (not shown) can also be connected to selected mould tools of at least the first, second and third mould tool sets 232, 242, 252. These vacuum lines can be operated as appropriate to extract liquid from the pre-form during the respective pressing Operation 128, 130, 132.

[0137] One or more of the mould tools of selected mould tool sets can have a construction that is in accordance with the disclosure in the Applicant's International Patent Application No. PCT / AU2020 / 051248. By way of example, the second lower mould tool 244 of the second press mould tool set 242 can include first and second layers, the second layer having interconnected internal voids that form part of the fluid extraction paths of the second lower mould tool 244.

[0138] A final moulded pulp fibre product M is formed as illustrated in Figure 4b and as previously described. Figure 5a is an illustrative example showing a vertical cross section of the slurry deposit that is accumulated on the porous mould 226, and which becomes Region A shown in Figure 4b.

[0139] Figures 5b to 5f illustrate an example of the geometry changes of the pre-form in the part of that corresponds with Region A. In Figures 5b to 5e, the shape illustrated in solid lines (and with cross section hatching) corresponds with a respective intermediate form of the pre-form at the conclusion of the respective pressing stage. In Figure 5f, the shape illustrated in solid lines (also with cross section hatching) corresponds with the form of the moulded pulp fibre product M. In each of Figures 5b to 5f, the mould tool set closure direction is indicated by arrow C. Further, in these Figures the dashed lines indicate the location of a surface of the slurry deposit (in the case of Figure 5b) and the pre-form (in the cases of Figures 5c to 5f) that is displaced as a result of the respective pressing stage.

[0140] Notably, in this particular example, the geometry changes illustrated are as follows: i. in Figure 5b (Operation 128 / Porous mould press):

[0141] - a reduction in the thickness of the accumulated refined pulp fibre, and

[0142] - a change in the geometric proportions of the accumulated refined pulp fibre; ii. in Figure 5c (Operation 130 / 1st pre-form press), a reduction in the thickness of the accumulated refined pulp fibre in a direction that is parallel to the relative movement of the opposing mould tool surfaces. In other words, the reduction is in a direction that is parallel to the mould tool set closure direction C; iii. In Figure 5d (Operation 132 I 2nd pre-form press), a reduction in the thickness of the accumulated refined pulp fibre in a direction that is generally transverse to the relative movement of the opposing mould tool surfaces. In other words, the reduction is in a direction that is generally transverse to the mould tool set closure direction C; iv. In Figure 5e (Operation 134 / 3rd pre-form press):

[0143] - a reduction in the thickness of the accumulated refined pulp fibre in directions that are both parallel and transverse to the relative movement of the opposing mould tool surfaces, and

[0144] - a relative displacement of two spaced apart surface portions of the accumulated refined pulp fibre, which in this example forms a rib to form on the underside of the accumulated pulp fibre; and v. in Figure 5f (Operation 1361 4thpre-form press) a reduction in the thickness of the accumulated refined pulp fibre in directions that are both parallel and transverse to the relative movement of the opposing mould tool surfaces. In addition, the geometric proportions of the rib are altered. More particularly, both the width and height of the rib are reduced.

[0145] Trial Process:

[0146] The following part of the description relates to a trial of the process 100 conducted by the Applicant using plant equipment that is substantially as described and illustrated in reference to Figures 4a and 4b.

[0147] In the trial process, the liquid used for the suspension was potable water, and the pulp fibre was commercially available dried bagasse pulp sheet.

[0148] The suspension was formed in a repulper constructed by Aikawa Iron Works Co., Ltd. (Model No. ADP 0.5M3).

[0149] The suspension was subjected to a deflaking stage, and four refining stages, using a deflaker I refiner constructed by Aikawa Iron Works Co., Ltd. (Model No. SDR-14) to create the pulp stock. The gap widths for each of these operations is set out in Table 1. TABLE 1:

[0150] The morphological characteristics of the pulp fibre in a sample the deflaked, but unrefined pulp stock (that is, after the deflaking stage 106, but prior to the 1strefining stage 110) was analysed using a MORFI NEO, manufactured by Techpap, of Gieres, France. The data* obtained from the MORFI NEO identified the following characteristics:

[0151] Fibre length - length weighted fibre length: 1,190 / zm (1.190 mm) mean arithmetic length: 592 zm (0.592mm)

[0152] Fibre width (mean): 23.2 / zm (0.0232 mm)

[0153] Fines content -

[0154] 39.81% (percentage in length of the suspension)

[0155] Shives content (by area): 1.3%

[0156] The above fibre analysis of the pulp fibre in the unrefined pulp stock is consistent with characteristics reported in literature; for instance, as reported in "Chemical and morphological characterization of sugar cane bagasse", Andrade MF, Colodette JL and Jameel H, Tappi J 13(6):27-33 (2014), which states:

[0157] Fibre length: 1.44 mm, SD = 0.5 mm.

[0158] Fibre width: 21.3 / zm, SD = 6.5 / zm. The morphological characteristics of the pulp fibre in the suspension after the deflaking stage are considered to be directly representative of the characteristics of the unrefined pulp fibre. This is because the deflaking action predominantly separates shives, with minimal work being performed on the individual fibres.

[0159] It is noted that the refining time in each of the deflaking and refining stages 106, 110, 112, 114, 116 influences the morphological characteristics of the pulp fibre. In respect of a disc-type refiner (such as used in this example), the flow rate of the suspension through the refiner has a correlation with refining time. By way of example, the shives content by area decreases with increased refining time in the deflaking stage.

[0160] The morphological characteristics of the pulp fibre in samples of the pulp stock (that is, after the 4threfining stage 116) was also analysed using the MORFI NEO. The data* obtained from the MORFI NEO identified the following characteristics:

[0161] Fibre length - length weighted fibre length: 901 / / m (0.901 mm) mean arithmetic length: 592 / / m (0.592mm)

[0162] Fibre width (mean): 22.7 / zm (0.027 mm)

[0163] Fines content -

[0164] 53.543% (percentage in length of the suspension) Primary fines ratio: 75.89%

[0165] Secondary fines ratio: 24.11%

[0166] Shives content (by area): 0.3 %

[0167] * Detail of the analysis procedures and techniques, terminology, and calculation methodology of the above characteristics is explained in the MORFI NEO User's Manual, Release 1.0.55, dated 7 June 2021, the contents of which are incorporated herein by reference.

[0168] For the purposes of this specification, and the claims that follow, values of a morphological characteristic of pulp fibre are to be determined having regard to the MORFI NEO instrument specification and parameters, and the analysis procedures and techniques, terminology, and calculation methodology as detailed in the MORFI NEO User's Manual.

[0169] Two observations are made regarding the above described morphological analyses of the unrefined pulp fibre in the suspension, and of the and pulp stock:

[0170] 1. the length weight fibre length of the pulp fibre is reduced in the refining stages by approximately 189 / m; hence, the length of the refined pulp fibres is approximately 76% of the length of the unrefined pulp fibres; and

[0171] 2. the fibre width of the pulp fibre is reduced in the refining stages by approximately 0.5 / m; hence, the fibre width of the refined pulp fibres is approximately 98% of the fibre width of the unrefined pulp fibres.

[0172] It will be appreciated that the values described above are statistical representations of the pulp fibres. The above values are means of a large number of analyses, as per the sampling protocols of the instrument, and processing of images by the software.

[0173] It will also be appreciated that different morphological analysing instruments may have specification and parameters that differ from the MORFI NEO, and / or use different analysis procedures and techniques, calculation methodology, and possibly even conflicting terminology. Accordingly, assessment of pulp fibres by other equipment may yield different results, in respect of nominal morphological characteristics referenced herein. The Applicant conducted mass fraction tests of refined pulp fibre that involved a screening classification procedure on the pulp stock to separate the pulp fibre from the fines and cellulosic microparticles present in the pulp stock. In this procedure, the Applicant separated the pulp fibre component from the fines and cellulosic microparticle component using a Brecht-Holl Classifier (produced by Rycobel) and using a mesh screen for separation of fibrous material smaller than 74 / zm. The separated pulp fibre component, and fines and cellulosic microparticle component were dried and weighed to determine the mass fraction of the fines and cellulosic microparticle within the pulp stock. The results of the mass fraction tests indicated that, by weight, the fines and cellulosic microparticle component accounted for approximately 57% of the fibrous material present in the pulp stock. While the mass fraction test does not measure the same characteristic as the morphological analysis provided by the MORFI NEO, it is considered that the cellulosic microparticle would make up approximately 3% by weight in the pulp stock. Hence, the morphological analysis of the fines component, measured in length by weighted length, that is provided by the MORFI NEO is comparable with the actual fines component by weight.

[0174] With respect to the second observation, those skilled in the art will appreciate that the difference in fibre width between the unrefined and refined pulp fibres is insubstantial.

[0175] Operation 108, as implemented in these trial processes, included analysis of the partially refined pulp fibre in the suspension (Operation 114c) after the 3rdpulp fibre refining stage (Operation 114). To this end, a sample of the suspension was taken and used in a Canadian Standard Freeness test (in accordance with TAPPI Standard Test Method T 227 om-21). An interim target freeness for the suspension going in to the 4thpulp fibre refining stage (Operation 116) was identified, having regard to the operating parameters of this process and equipment. On the basis of the deviation of the freeness per the analysis in Operation 114c (in other words, the refining progress indicator) from the interim target freeness, the gap width of the refiner for the 4th pulp fibre refining stage (Operation 116) was set.

[0176] Where the refining progress indicator is higher than the interim target freeness (indicating an insufficient level of refining at the conclusion of the 3rdrefining stage 114), the gap width is set to more aggressively refine the pulp fibre in the final refining stage (Operation 116). Hence, a refining progress indicator that suggests a "more free" suspension, the gap width in the 4threfining stage 116 is to be set towards the lower end of the range in Table 1. Conversely, where the refining progress indicator is lower than the interim target freeness (indicating a high level of refining at the conclusion of the 3rdrefining stage 114), the gap width is set to effect less refining of the pulp fibre in the final refining stage (Operation 116). Hence, a refining progress indicator that suggests a "less free" suspension, the gap width in the 4threfining stage 116 is to be set towards the upper end of the range in Table 1.

[0177] The pulp stock was made with a low pulp fibre fraction. In this example, the suspension has a liquid fraction of the order of 99.2% (and a solid fraction of the order of 0.8%). The refined pulp fibre in the suspension that makes up the pulp stock had a Canadian Standard Freeness in the range of approximately 100 to 150 mL CSF.

[0178] Additives were added to the pulp stock in the make-up tank 220 1 flow line 222. In this example, Alkyl Ketene Dimer (AKD) (at up to approximately 0.3% by volume), and Polyaminopolyamide-epichlorohydrin (PAE) (at up to approximately 0.6% by volume) were added prior to accumulating wet refined pulp fibre (Operation 122) on forming surfaces 228 of the porous mould 226. Once the wet refined pulp fibre was accumulated on the forming surfaces 228, the slurry deposit underwent a series of pressing stages (Operation 124) between opposing mould tool surfaces. In this example, Operation 124 involved five pressing operations 126, 128, 130, 132, 134 as described previously and illustrated in reference to Figures 3 and 4b to extract liquid.

[0179] The approximate liquid content of pulp fibre material as it progresses through the series of pressing stages (Operation 124) from the accumulated slurry deposit to the final moulded pulp fibre product M in this example is set out in Table 2.

[0180] TABLE 2:

[0181] As will be apparent from Table 2, the liquid content reduction of the pre-form as it progresses the series of pressing stages (Operation 124) is non-linear. The progressive, non-linear reduction in liquid content through the porous mould pressing stage 126, and the 1st, 2nd, 3rd pre-form pressing stages 128, 130, 132 facilitates the manipulation of the pulp fibre material from the form of the accumulated slurry deposit towards the final moulded product form, whilst managing the increasing strength of the inter-fibre bonds that are established internally within the pulp fibre network.

[0182] In some examples of the process 100, the 3rdpre-form press stage 132 may be implemented reduce the liquid content to 0.0%, or at least to a liquid content that is too low to measure. The geometric changes of the accumulated refined pulp fibre that was obtained in respect of the pre-form as illustrated in Figures 5a to 5f is set out in Table 3.

[0183] TABLE 3:

[0184] * Parallel and transverse directions are relative to the respective tool set closure direction C

[0185] It is evident from the transverse deflection indicated in Table 3 that the process 100 can achieve significant transverse deflection of the pulp fibre pre-form during the 2ndand 3rdpre-form press stages 130, 132. An advantage of the process is that the density of sections of the final moulded pulp fibre product that have a relatively high draft angle (of the order of 10° to 5°) can be at least equal to, if not greater than, the density of the sections of the final moulded pulp fibre product that have surfaces substantially transverse to the mould tool set closure direction C.

[0186] In one example, the Applicant has formed final moulded pulp fibre products M using the process 100, with mould tool sets that form sections in the products M with a draft angle of approximately 8°. These sections were measured to have a material density in the range of at least approximately 900 kg / m3, and up to approximately 1,150 kg / m3. Further, within these sections, the wall thickness was in the range of approximately 275 / m to 380 / m. By contrast, an equivalent moulded pulp fibre product formed using previously known thermoforming I precision forming processes, and having a similar wall thickness at this draft angle, would typically have a material density in the range of 250 to 400 kg / m3. For clarity, throughout this specification, and in the claims that follow, expressions relating to "reducing the thickness" where expressed as a percentage are to be understood to refer to the change in material thickness (in the indicated direction), as a proportion of the material thickness (in the same indicated direction) prior to the reduction, and expressed as a percentage.

[0187] In addition, surface roughness measurements were taken of external surfaces the sections in the products M with a draft angle of approximately 8°. These sections were measured to have an arithmetic mean height surface roughness (Sa) (which is the absolute value of the difference in height of each point on the surface, compared to the arithmetical mean of that surface) in the range of 6.549 to 10.065 / / m. By contrast, an equivalent moulded pulp fibre product formed using previously known thermoforming I precision forming processes would typically have an arithmetic mean height surface roughness (Sa) of approximately at least an order of magnitude higher.

[0188] In some end applications in which the moulded pulp fibre products produced by the process 100, it may be desirable and / or necessary to coat the moulded pulp fibre material with material(s) in a liquid state, which then cure / dry to be in a solid state at standard atmospheric conditions. The Applicant has observed that moulded pulp fibre products having pulp fibre densities of the order described above can provide the advantage of limited permeability to the coating materials in liquid state. By way of example only, application of a liquid wax to the moulded pulp fibre material produced by the process 100 can be achieved with negligible permeation of the liquid wax into the pulp fibre material. This property of the moulded pulp fibre has the benefits of reducing the quantity of coating material that needs to be applied, and / or mitigating imperfections in the coating itself.

[0189] Figure 6 shows a process for forming a moulded pulp fibre product 400 according to another embodiment. Operations in the process 400 that are the same or similar to operations of the process 100 have the same reference numbers with the prefix "1" substituted with the prefix "4" and for succinctness, will not be described again. The principle difference between the two processes 100, 400 is that the process 400 does not include pulp refining stages. In some instances, the pulp stock is formed of a suspension of disintegrated pulp fibres that have not been subjected to any refinement. In some other instances, the raw pulp fibre can be subjected to dry refining process(es), prior to forming the suspension to create the pulp stock.

[0190] Figure 6 illustrates the series of pressing stages 424, broadly involves a series of two or more pressing stages that are configured to progressively extract liquid from the slurry deposit. In the example illustrated in Figure 6, there is an initial press stage 424a, which is followed by one or more subsequent press stages 424b.

[0191] As the slurry deposit progresses through the series of pressing stages 424, the geometry of the accumulated refined pulp fibre changes from the initial slurry deposit form into the final moulded pulp fibre product form. As each pressing stage in the two or more pressing stages 424a, 424b in this example uses separate mould tools to provide the opposing mould tool surfaces at each pressing stage, the geometry of the initial slurry deposit form into the final moulded pulp fibre product form may have a number of intermediate forms that is one less than the number of subsequent pressing stages 424b used in the process 400.

[0192] In the examples described herein and illustrated in the drawings, bagasse is used as the pulp fibre. It will be understood that the process, and products formed by the process, may use other plant-derived fibres, and / or cellulose obtained from other materials. Further, the process, and products formed by the process, may use plant-derived fibres from more than one plant species, and / or source. By way of non-limiting example, other plant-derived fibres include: bamboo, cotton, hemp, straw (rice, wheat, pea), flax, palm, and wood. Sample materials:

[0193] The Applicant prepared comparative samples of pulp fibre materials (formed as handsheets) from each of bagasse, bamboo, and wheat straw pulp stock. For consistency and repeatability, each sample for testing was a handsheet formed from the selected pulp fibre in accordance with TAPPI Standard Test Method T 205 sp-12.

[0194] The pulp fibre stock used in forming the samples was: a. commercially available dried bagasse pulp sheet ("raw bagasse stock"); b. commercially available dried bamboo pulp ("raw bamboo stock"); and c. commercially available wheat straw pulp obtained from Nafici Environmental Research Ltd ("raw wheat straw stock").

[0195] A first portion of the raw bagasse stock was set aside for analysis and sample preparation. A second portion of the raw bagasse stock was refined by a process that was substantially in accordance with the refining stage Operations 110, 112, 114, 116 of the trial process described above. This refining process formed a refined bagasse stock.

[0196] Similarly, first portions of each of the raw bamboo stock, and raw wheat straw stock were set aside for analysis and sample preparation. A second portion of each of the raw bamboo stock, and raw wheat straw stock was refined using a Laboratory Disc Refiner (Bauer type) constructed by IDM Instruments Pty Ltd (Model No. MD- 3000). The refiner was fitted with a Finebar type refining disc, and set with a gap width of 0.5mm. The respective pulp material was refined for 30 minutes. This was determined to provide substantially equivalent pulp fibre refinement as that performed on the raw bamboo stock (noting that the actual outcomes are dependent on individual refiner characteristics, and on the pulp materials themselves). This refining process formed a refined bamboo stock, and a refined wheat straw stock. Prior to forming the handsheets, Canadian Standard Freeness tests (in accordance with TAPPI Standard Test Method T 227 om-21) were performed on each of the first portions of the respective pulp stock. Similarly, the morphological characteristics of the pulp fibre within each of the first portions of the respective pulp stock of pulp stock was determined using the MORFI NEO. The results of these tests and analyses are set out in Table 4 below. Analysis of the shives content / characteristics was not performed on the respective pulp stocks.

[0197] TABLE 4:

[0198] In Table 4, the 2nd to 6th columns are as follows:

[0199] CSF - Canadian Standard Freeness (measured in millilitres I mm);

[0200] LWFL - Length-weighted fibre length (measured in micrometres I / m);

[0201] MAL - Mean arithmetic fibre length (measured in micrometres I / m);

[0202] MFW - Mean Fibre Width (measured in micrometres I and Fines - Fines content (percentage in length of the suspension).

[0203] Each of the refined pulp stocks was formed by refining the corresponding raw pulp stock. Hence, the mean fibre width of the refined pulp stocks, as a percentage of the mean fibre width of the raw pulp fibre can be determined directly from the data in Table 4. For clarity, the mean fibre width of the raw pulp fibre is also referred to in this specification and the claims that follows as term "mean raw fibre width". For the three refined pulp stocks, the mean fibre width as a percentage of the mean raw fibre width is as follows: Refined bagasse: 99.13%

[0204] Refined bamboo: 113.33%

[0205] Refined wheat straw: 94.09%

[0206] Within the recorded fines content, the proportion of primary and secondary fines was determined, and is set out in Table 5 below.

[0207] TABLE 5:

[0208] Selected material properties and characteristics of the samples handsheets were obtained by tests, or calculated, as described below.

[0209] Thickness - obtained using standard laboratory equipment, and in accordance with TAPPI Standard Test Method T551 om-98, "Thickness of paper and paperboard (soft platen method)", and expressed in mm,

[0210] Mass - obtained using standard laboratory equipment, and in respect of a 75 mm diameter section of the sample handsheet,

[0211] Density - calculated, using the sample thickness and mass results, and expressed in both GSM (g / m2), and kg / m3, Water vapour transmission rate (WVTR) - obtained using standard laboratory equipment, and in accordance with TAPPI Standard Test Method T448 om-09, "Water vapor transmission rate of paper and paperboard at 23°C and 50% RH", and expressed in g / m2.day,

[0212] Water vapour permeance (WVP) - calculated, using the sample WVTR and thickness results, and expressed in g / m2.day / kPa.m3,

[0213] Water absorbency (Cobb 60) - obtained using standard laboratory equipment, a Cobb tester, and in accordance with TAPPI Standard Test Method T 441 om-09, "Water absorptiveness of sized (non- bibulous) paper, paperboard, and corrugated fiberboard (Cobb test)"; 60 second test, and expressed in g / m2(of water absorbed),

[0214] Air permeance (AP) - obtained using a L&W Air Permeance Tester, and expressed in mL / min,

[0215] Edgewise compression strength (Ring crush strength) - obtained using standard laboratory equipment, and in accordance with TAPPI Standard Test Method T818 cm-97, "Ring crush of paperboard", and expressed in MPa,

[0216] Maximum shear punch force (Shear punch) - obtained using a modified Instron machine to push a 9.8mm diameter pin through a sample clamped between a pair of plates with aligned 10mm diameter holes, and expressed in N,

[0217] Shear strength - calculated, using sample shear punch force results, and expressed in MPa. The following tables provide summary results of the tests and calculations. Where tests were repeated on a single sample handsheet, and / or multiple sample handsheets were tested, the values shown in the tables are averages.

[0218] TABLE 6:

[0219] Observations: the data in Table 6 shows that, for all pulp materials tested, refining the pulp fibre results in the refined stock handsheet samples being thinner, compared with the unrefined stock handsheet samples. This is considered to be a consequence of the fibre refinement enabling the pulp fibres to assemble more tightly within the pulp matrix of the respective refined material, compared with the corresponding unrefined material.

[0220] It is noted that the density measurements of the sample handsheets formed from refined bamboo stock was less than that of the raw (unrefined) bamboo stock. In this regard, inspection of the data in Table 4 reveals that the mean fibre width (MFW) of the bamboo, as determined by the morphological data, increased. This is considered to be a result of the refining process performed on the bamboo pulp fibre to alter the fibre width distribution. It is considered likely that this property of the bamboo refinement, combined with the refined bamboo sample handsheets having a lighter mass, resulted in a lower density material.

[0221] TABLE 7:

[0222] Observations: the data in Table 7 shows that, for all pulp materials tested, refining the pulp fibre results in refined pulp handsheet samples with improved material characteristics, compared with the corresponding unrefined pulp handsheet samples, in respect of each of water vapour transmission rate, water vapour permeance, water absorbency, and air permeance.

[0223] TABLE 8: Observations: the data in Table 8 shows that, for all pulp materials tested, refining the pulp fibre results in refined pulp handsheet samples with improved maximum shear punch force, and shear strength characteristics, compared with the corresponding unrefined pulp handsheet samples.

[0224] TABLE 9:

[0225] Observations: the data in Table 9 shows that, for all pulp materials tested, refining the pulp fibre results in refined pulp handsheet samples with improved edgewise compression strength (as measured by the Ring Crush tests), compared with the corresponding unrefined pulp handsheet samples.

[0226] The results of the tests conducted in respect of the sample handsheets demonstrate the suitability of refined bagasse, bamboo, and wheat straw for forming moulded pulp products in accordance with the processes described herein. It will be appreciated that the selection of pulp fibre(s) from which any moulded pulp fibre product is formed is made having regard to various factors, including the material suitability for the desired application.

[0227] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated feature, integer, operation or step, or group of features, integers, operations or steps, but not the exclusion of any other feature, integer, operation or step, or group of features, integers, operations or steps. Processes and / or procedures described herein will be understood to only imply a sequence or order of the operations, stages, or steps where the context necessitates the sequence or order. In other circumstances, processes and / or procedures described herein may proceed with operations, stages, or steps, in any order, and / or with intermediate operations, stages, or steps.

[0228] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

CLAIMS:

1. A process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving: forming a suspension of pulp fibre and liquid, and passing the suspension through a series of refining stages that each refine the pulp fibre, whereby the refined pulp fibre within the pulp stock has a mean fibre length that is less than the mean length of the raw pulp fibre from which the suspension is created, and has a proportion of fines by length in the pulp fibre component of the suspension that is at least 45%; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet refined pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated refined pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to refined pulp fibre, and working the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

2. A process according to claim 1, wherein creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is 90% or greater of the mean raw fibre width.

3. A process according to claim 1, wherein creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is 95% or greater of the mean raw fibre width.

4. A process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving:forming a suspension of pulp fibre and liquid, and passing the suspension through a series of refining stages that each refine the pulp fibre, whereby the refined pulp fibre within the pulp stock has a mean fibre length that is less than the mean length of the raw pulp fibre from which the suspension is created, and the refined pulp fibre within the pulp stock has a mean fibre width that is 90% or greater of the mean raw fibre width; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet refined pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated refined pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to refined pulp fibre, and working the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

5. A process according to claim 4, wherein creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is 95% or greater of the mean raw fibre width.

6. A process according to any one of claims 1 to 5, wherein creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width that is substantially unchanged from the mean raw fibre width.

7. A process according to any one of claims 1 to 6, wherein pressing the slurry deposit between opposing mould tool surfaces includes a series of two or more pressing stages that are configured to progressively extract liquid from the slurry deposit, wherein the geometry of the accumulated refined pulp fibre changes from the initial slurry deposit forminto the final moulded pulp fibre product form with progression through the series of pressing stages.

8. A process according to claim 7, wherein the change in geometry of the accumulated refined pulp fibre from the initial slurry deposit form into the final moulded pulp fibre product form includes one or more intermediate forms that are formed by a respective one of the series of pressing stages prior to the final pressing stage.

9. A process according to either claim 6 or 7, wherein the geometry change of the accumulated refined pulp fibre at each pressing stage involves any one or more of: a reduction in the thickness of part(s) or the entirety of the accumulated refined pulp fibre; a change in the geometric proportions of the accumulated refined pulp fibre; or a relative displacement of two spaced apart surface portions of the accumulated refined pulp fibre.

10. A process according to any one of claims 1 to 9, wherein creating the pulp stock involves refining the pulp fibre to a Canadian Standard Freeness of less than approximately 300 mL CSF.

11. A process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving: forming a suspension of pulp fibre and liquid, and passing the suspension through a series of refining stages that each refine the pulp fibre, such that the pulp stock has a Canadian Standard Freeness of less than approximately 300 mL CSF; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product;accumulating wet refined pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated refined pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to refined pulp fibre, and working the accumulated refined pulp fibre from the slurry deposit form into the final moulded pulp fibre product form.

12. A process according to either claim 10 to 11, wherein creating the pulp stock involves refining the pulp fibre to a Canadian Standard Freeness of 100 to 150 mL CSF.

13. A process according to according to any one of claims 1 to 12, wherein each refining stage involves passing the suspension through at least one refiner that has a rotor and stator defining a gap therebetween through which to pass the suspension, wherein the series of refining stages is arranged such that the width of the gap is reduced between at least some consecutive stages in the series.

14. A process according to claim 13, wherein the series of refining stages includes an initial refining stage, and one or more subsequent refining stages, and the process includes setting the width of the gap between the rotor and stator prior to passing the suspension through each of the subsequent refining stages.

15. A process according to claim 14, wherein setting the width of the gap prior to passing the suspension through each of the subsequent refining stages is made:- in accordance with a predetermined protocol, and / or- based on analysis of the partially refined pulp in the suspension to target predetermined suspension characteristics at the completion of the respective subsequent refining stage.

16. A process according to either claim 14 or 15, wherein setting the width of the gap involves reducing the width of the gap between the rotor and stator, compared with the width of the gap of the immediately preceding refining stage.

17. A process according to any one of claims 1 to 16, wherein the pulp fibre from which the pulp stock is created is bagasse, and wherein creating the pulp stock involves refining the pulp fibre such that within the refined pulp stock the mean pulp fibre length is less than or equal to 1 millimetre.

18. A process according to any one of claims 1 to 17, wherein creating the pulp stock involves passing the suspension through the series of refining stages such that the refined pulp fibre within the pulp stock has a mean fibre width is within the range of 15 to 25 / / m.

19. A process according to any one of claims 1 to 18, wherein creating the pulp stock further involves refining the pulp fibre such that the proportion of the fines in the pulp stock that are secondary fines is less than one third.

20. A process according to any one of claims 1 to 19, wherein creating the pulp stock further involves refining the pulp fibre such that the shives content measured by imaging techniques constitutes a fibrous area that is less than 0.5%.

21. A process according to any one of claims 1 to 20, wherein creating the pulp stock further involves refining the pulp fibre such that the refined pulp fibre within the pulp stock has a fibrillation index that is at least 1%.

22. A process according to any one of claims 1 to 21, wherein creating the pulp stock further involves refining the pulp fibre such that the pulp stock has a fines content that is less than or equal to 65% in length.

23. A process according to any one of claims 7 to 9, wherein reduction in the thickness of part(s) of the slurry deposit in any one of the pressing stages involves:a reduction in a direction that is parallel to the relative movement of the opposing mould tool surfaces; in directions that are transverse to the relative movement of the opposing mould tool surfaces; or in directions that are parallel and transverse to the relative movement of the opposing mould tool surfaces.

24. A process for forming a moulded pulp fibre product, the process involving: creating a pulp stock, involving forming a suspension of pulp fibre and liquid; providing a porous mould having one or more pre-form mould portions that each have a forming surface with a shape that corresponds generally with a part of an external surface of the final moulded pulp fibre product; accumulating wet pulp fibre on the forming surfaces of the pre-form mould portions by progressing the pulp stock towards the porous mould and removing liquid through the porous mould, the accumulated pulp fibre forming a slurry deposit; and pressing the slurry deposit between opposing mould tool surfaces to extract liquid, thereby reducing the ratio of liquid to pulp fibre, and working the pulp fibre from the slurry deposit form into the final moulded pulp fibre product form, wherein the geometry of the accumulated pulp fibre changes from the initial slurry deposit form into the final moulded pulp fibre product form with progression through the series of pressing stages.

25. A process according to claim 24, wherein the geometry change of the accumulated pulp fibre at each pressing stage is any one or more of: a reduction in the thickness of part(s) or the entirety of the accumulated pulp fibre; the geometric proportions of the pulp fibre; or a relative displacement of two spaced apart surface portions of the accumulated pulp fibre.

26. A process according to claim 25, wherein a reduction in the thickness of part(s) of the slurry deposit in any one of the pressing stages involves: a reduction in a direction that is parallel to the relative movement of the opposing mould tool surfaces; in directions that are transverse to the relative movement of the opposing mould tool surfaces; or in directions that are parallel and transverse to the relative movement of the opposing mould tool surfaces.

27. A process according to either claim 25 or 26, wherein each of the pressing stages involves reducing the thickness of the slurry deposit in any one direction by less than or equal to 50%.

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