Abstract
A fibre processing apparatus for use in mechanical manipulation and/or processing of material. The apparatus includes an inlet at a first end for introduction of material and/or liquid contained in the material, an outlet downstream of the inlet which manipulated and/or processed material and/or liquid leaves, intermediate the inlet and outlet is a screw processor including at least one shaft having an axis of rotation, the shaft having a plurality of elements provided to cause mechanical manipulation and/or processing and/or cutting of the material. At least one of the plurality of element includes a partially textured exterior surface or wall. The manipulated/processed material being selected from a group of: fibres, cellulose fibres, powders, granules, foodstuffs, pharmaceuticals and/or plastics. The invention further discloses a screw processor element and a method of treating a composition comprising cellulose fibre.
Claims
1. An apparatus for use in the mechanical manipulation and/or processing of a material, said apparatus comprising: an inlet at a first end for introduction of the material and/or liquid in which said material is contained, in use; an outlet downstream of the inlet and via which the manipulated and/or processed material and/or liquid leaves, in use; and intermediate the inlet and outlet there is provided a screw processor including at least one shaft with an axis of rotation and on which is provided a plurality of elements provided to cause mechanical manipulation and/or processing and/or cutting of said material, in use, and wherein at least one of the plurality of elements includes an exterior surface or wall that is at least partially textured.
2. (canceled)
3. (canceled)
4. (canceled)
5. An apparatus according to claim 1, wherein the at least one element includes a first surface or wall around the periphery thereof, and further includes second and third spaced apart surfaces or walls which are substantially perpendicular to the first surface or wall, and wherein the first, second and third surfaces or walls, or any combination thereof, are textured.
6. An apparatus according to claim 1, wherein the texturing is selected from the group consisting of: a series of serrations, ridges, steps, and any or any combination of pinned, toothed, grooved and/or spiked formations.
7. (canceled)
8. (canceled)
9. An apparatus according to claim 1, wherein the screw processor includes at least two substantially parallel or angularly offset shafts with the plurality of elements mounted on respective shafts and located by the shafts such that the same intermesh.
10. An apparatus according to claim 1, wherein the screw processor is provided as a twin-screw processor, and one or more elements provided on a first shaft or screw are arranged to intermesh and/or engage complementary elements provided on a second shaft or screw of the screw processor.
11. An apparatus according to claim 1, wherein the screw processor is provided with 4, 6, 8, 10 or more shafts, and the shafts with the plurality of elements mounted thereon are provided to intermesh with plurality of elements provided on an adjacent shaft or shafts.
12. An apparatus according to claim 1, wherein the at least one shaft includes the plurality of elements having varying sizes located thereon and provided to intermesh with corresponding plurality of elements of varying sizes located on one or more adjacent shafts provided in the screw processor.
13. An apparatus according to claim 1, wherein a plurality of shafts is arranged parallel to, and about, a central, longitudinal axis of the screw processor, providing a substantially planetary configuration of the screw processor, such an arrangement being provided wherein at least four shafts are provided.
14. An apparatus according to claim 1, wherein form of the textured surface and/or surfaces is varied in frequency, depth, pitch and angle between individual elements and/or differing surfaces of the same element.
15. An apparatus according to claim 1, wherein said elements are provided as any or any combination of mono-lobal, bi-lobal, tri-lobal and/or asymmetric elements, in order to provide improved processing efficiency, in use.
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. An apparatus according to claim 1, wherein at least some of the plurality of elements are provided with a shape wherein a circumference of the plurality of elements follows a path of a substantially circular sine wave.
21. An apparatus according to claim 20, wherein peaks of a first element on a first shaft are arranged to engage and/or intermesh troughs of a second element on a second shaft, and vice versa.
22. An element for use with a screw processor, said element comprising: a first exterior wall or surface; second and third spaced apart exterior surfaces that are substantially perpendicular to the first exterior wall or surface, and wherein at least one of the walls or surfaces is provided with an at least partially textured surface.
23. An element according to claim 22, wherein the element has a channel formed therethrough, which allows the same to be mounted on a shaft, and engagement means are provided to allow the element to be rotated along with the shaft.
24. An element according to claim 23, wherein the element is provided with a substantially circular profile, and the channel is provided offset from a central axis of the element.
25. An element according to claim 22, wherein the second and/or third surfaces are formed having a series of formations in a form selected from the group consisting of: spots, pimples, recessed versions of the same and/or the like provided thereon, or having a series of serrations or rib members thereon.
26. An element according to claim 25, wherein the serrations are provided as a series of concentric serrations provided about the channel or are located parallel to one another along a length of the surface or surfaces.
27. An element according to claim 25, wherein the rib members are provided to extend radially about the channel from the channel to a periphery of the surface or surfaces, or are located parallel to one another along a length of the surface or surfaces.
28. (canceled)
29. A method of treating a composition comprising cellulose fibres, said method includes the steps of: providing a composition comprising cellulose fibres; admixing aqueous solution/solvent to the composition comprising cellulose fibres to provide a pulp suspension comprising cellulose fibres; feeding the pulp suspension into an apparatus for use in de-fibering/defibrillation of the cellulose fibres, the apparatus having an inlet at a first end for introduction of the pulp suspension and an outlet downstream of the inlet via which the pulp suspension leaves, intermediate the inlet and outlet there is a screw processor including at least one shaft with an axis of rotation on which a plurality of elements are provided to cause mechanical manipulation and/or processing and/or cutting of the pulp suspension, and processing the pulp suspension comprising cellulose fibres with at least use of the screw processor to provide a composition comprising cellulose micro/nanofibers.
30. A method according to claim 29, wherein minerals and other additives such as colour, polymers, waterproofing agents, can be added to the composition during the defibrillation process.
Description
[0094] Embodiments of the present invention will now be described with reference to the accompanying figures, wherein:
[0095] FIG. 1 illustrates a pair of bi-lobal elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0096] FIG. 2 illustrates a monolobal element that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0097] FIGS. 3a-c illustrate pairs of monolobal elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0098] FIGS. 4a-b illustrate an alternative monolobal element that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0099] FIG. 5 illustrates a cut-away portion of a pair of complementary clusters of elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0100] FIGS. 6a-d illustrate a further embodiment of a pair of complementary clusters of elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0101] FIGS. 7a-c illustrate an example of a screw processor in accordance with one embodiment of the invention, FIGS. 7d-f illustrate elements of the processor in greater detail, and FIG. 7g illustrates a single screw processor variant, all in accordance with an embodiment of the present invention;
[0102] FIGS. 8a-h illustrate images of fibres which are subjected to differing amounts of defibrillation using the apparatus in accordance with one embodiment of the invention; FIGS. 9a-e illustrate embodiments of screw designs in accordance with embodiments of the invention;
[0103] FIGS. 10a-c illustrate example of complete screw configurations in accordance with embodiments of the invention;
[0104] FIGS. 11a-c illustrate pairs of monolobal elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0105] FIGS. 12a-c illustrate monolobal elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0106] FIG. 13 illustrates a front view of a screw processor having elements arranged in a linear configuration, in accordance with an embodiment of the present invention
[0107] FIG. 14 illustrates a front view of a screw processor having elements arranged in a planetary configuration, in accordance with an embodiment of the present invention;
[0108] FIGS. 15a-c illustrate further elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0109] FIGS. 16a-b illustrate further elements on parallel linear shafts that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0110] FIGS. 17a-c illustrate further elements in the form of cog-like members that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0111] FIGS. 18a-f illustrate further elements in the form of cog-like members having one or more apertures located therethrough, in accordance with embodiments of the present invention;
[0112] FIGS. 19a-d illustrate elements provided on two or more non-parallel shaft members, in accordance with embodiments of the present invention;
[0113] FIGS. 20a-b illustrate further elements that can be incorporated into an apparatus in accordance with embodiments of the present invention; and
[0114] FIGS. 21a-d illustrate further images of the monolobal elements depicted in FIGS. 11 and 12, which can be incorporated into an apparatus in accordance with embodiments of the present invention.
[0115] FIGS. 22a-c illustrate a further type of elements and their arrangements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0116] FIGS. 23a-c illustrate variation in the exterior surface of a further type of elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0117] FIG. 24 illustrates a grouping arrangement of a further type of element that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0118] FIG. 25 illustrates a grouping of aligned tri-lobal elements that can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0119] FIGS. 26a-b illustrate groupings of tri-lobal elements provided along a shaft wherein adjacent or abutting elements are provided to be rotationally offset from one another, and which can be incorporated into an apparatus in accordance with embodiments of the present invention;
[0120] FIG. 27 illustrates further images of elements that can be incorporated into an apparatus in accordance with embodiments of the present invention; and
[0121] FIGS. 28a-c illustrate further detail of texturing of surfaces of elements that can be incorporated into an apparatus in accordance with embodiments of the present invention.
[0122] The present invention relates to the provision of screw elements that are to be incorporated into apparatus for the mechanical manipulation and/or processing of a material. The material may selected from any of the following groups: fibres, cellulose fibres, powders, granules, foodstuffs, pharmaceuticals and/or plastics. In particular, however, the following description will refer mainly to apparatus used for the defibering and/or defibrillation of cellulose fibres. This should not, however, be seen as limiting and the skilled person will understand that the apparatus and methods of the present invention may be applied to other such materials, as mentioned. The apparatus in general (not shown) includes at least one screw assembly, located between an inlet at a first end for the introduction of the cellulose fibres and/or liquid/and/or steam/and/or filler/and/or waterproofing agents/and/or chemical modifiers with which said fibres are mixed, and an outlet at an opposing end via which the processed fibres leave. The screw assemblies will have, located thereon, a number of screw elements provided to appropriately process the cellulose fibres. The screw elements are provided at various points along the length of the screw assembly, the positions and number of which may be varied according to the particular fibres and/or degree of processing that is to be carried out. FIG. 1 illustrates a pair of bi-lobal screw elements 1, which are provided to be incorporated onto at least one screw assembly as described above. The elements 1 have a channel 3 with a shaft engagement formation which can be manufacturer specific, provided extending therethrough, which allows for the elements 1 to be located on the shaft of the screw assembly. The elements 1 are provided with essentially three exterior walls or surfaces: the first surface 5 extends around the periphery of the element 1 and has a surface that is substantially parallel to the walls of the channel 3; and the remaining two surfaces are provided substantially perpendicular to the walls of the channel 3, these being effectively front 7 and rear 9 faces of the elements 1. Traditionally, screw elements of the prior art that are provided for use in refining cellulose fibres have smooth surfaces-some may have a bi-lobal shape as in FIG. 1, or may be provided with a helical shape, but the outer surfaces remain smooth. The elements 1 of the present invention are provided such that at least one of the exterior surfaces 5, 7, 9 is provided as having at least a partially textured surface.
[0123] The elements 1 may be provided on a single screw assembly which is located in an elongate channel or barrel of the apparatus and through which the fibres or fibre pulp suspension is injected for processing. In the embodiments where a single screw conveyor is provided, not only may the elements 1 be provided as having textured surfaces for improving the gripping and/or reduction in fibre size of fibres, the interior walls of the elongate channel in which the shaft of the screw assembly is located may also be textured in a similar fashion. In other embodiments, the apparatus may be provided as having a screw arrangement, where at least two screw assemblies are provided adjacent one another and the elements described above are provided along both screw assemblies.
[0124] In one embodiment, the channel walls may also be textured.
[0125] As is shown in FIG. 1, the parallel surface 5 is provided with texturing in the form of serrations 11, located across the majority of the surface 5, in four sectionsthe two ends of the lobes and the mid-points therebetween have substantially flat regions, although this may be varied in alternative embodiments. In other examples of the present invention, the texturing provided may be in the form of any or any combination of grooved, toothed, pinned and/or spiked formations 1511, as shown in FIG. 15a-c. As the elements 1 are provided along the screw conveyor, and in the case of a twin screw assemblies, often in complementary pairs, the action created by the rotating elements 1, such as scissor action, serves to cut and grab the fibre, if required, efficiently shortening and/or restructuring the fibre surface but not impairing the fibre quality. The provision of, for example, the serrations 11 on the surface 5 help to grip the fibre during the cutting process, thereby providing greater efficiency than an equivalent element with wholly smooth surfaces. Although not shown in FIG. 1, it is entirely feasible that the elements 1 may be provided with texturing on one or more of the perpendicular faces 7, 9, in particular, on the front face 7 as this is facing the inlet of the apparatus and will have the flow of fibre/fibre pulp suspension moving towards it. Furthermore, elements 1 may be provided with varying widths and, therefore, varying areas of the parallel surface 5 thereon, as required.
[0126] Referring now to FIG. 2, there is illustrated another screw element 201, which again is provided with a textured parallel face 205, however, in this embodiment, the serrations 211 extending across the face 205 do so at a slight angle. This is shown more clearly in FIGS. 3a-c, where similar elements 301 are shown in pairs, which would complement one another when both located on a screw conveyor. In FIGS. 3a-c, the serrations 311 are shown extending across the parallel face 305 at a far greater angle. As shown in FIG. 3b, the bore 303 of the elements 301 through which the screw extends can be provided off-centre. The rotating action of paired/complementary elements 301 then serves to first separate and then de-fibre and or defibrillate the fibres. The serrations 311 may also be provided as opposing textures/formations between paired/complementary elements 301, located on adjacent screws. This will help to achieve differing effects of defibering/defibrillating and other effects on the source fibre. As can be seen from the difference in the serrations 11, 211, 311 throughout FIGS. 1-3c, texturing of a surface 5, 7, 9 of the elements can be varied according to the specific fibre that is to be processed and, typically, the size and pitch of each of the said elements may be varied according to the specific fibre that is to be processed.
[0127] FIG. 4a illustrates a further embodiment of a screw element 401, which as with the previously described elements is provided with serrations 411 located around the parallel face 405, but is also provided with additional, concentric serrations 413 on the perpendicular face 407. The serrations 413 in this instance are provided on the front perpendicular face 407, such that as the fibre/fibre pulp suspension enters the apparatus through the inlet, they contact the textured face 407 that is facing them, which adds to the efficacy by which the fibres are cut and refined, in addition to the textured parallel surface 405. Whilst it is shown in this particular embodiment that the texturing is provided by concentric serrations 413 on the perpendicular face, it will be appreciated that other types of serration, such as diametric serrations, or different texturing entirely, may be provided. For example, the texturing may be provided as formations protruding from the face, i.e., sharpened dimples, or, etchings in a criss-cross pattern-the principle being to provide a roughened or uneven surface which ultimately grips the fibres more effectively and enables more efficient and quicker processing of the same, while avoiding causing damage to the fibre surface. FIG. 4b illustrates a cross-section of the element 401 shown in FIG. 4a, and further illustrates that both perpendicular faces 407, 409, may be provided with a textured surface, again in this instance, concentric serrations 413.
[0128] FIGS. 11a-c illustrate similar images to those of FIGS. 3a-c, however, the perpendicular faces 1107, 1109 are now provided with texturing. In the embodiments shown in FIGS. 11a-c, a series of rib members 1121 are provided on the perpendicular faces 1107, which extend radially from the bore 1103 to the periphery of the surface 1107. To further enhance the profile of the rib members 1121, a series of troughs 1123 may be located between adjacent rib members 1121. FIGS. 12a-c illustrate further examples of texturing which may be provided on the perpendicular faces 1107, 1109 of the screw element 1101. For example, as shown in FIG. 12a, a series of formations in the form of spots, pimples, recesses 1125 and/or the like may be provided on the faces 1107, 1009. FIG. 12b illustrates the provision of a series of ribs or serrations 1127 but, unlike the concentric serrations shown in FIGS. 4a-b, the ribs or serrations 1127 are located parallel to one another along a length of the perpendicular face 1107, 1109. In a further embodiment, shown in FIG. 12c, the serrations 1129 may be provided to extend radially about the bore 1103, to the periphery of the face 1107, 1109. FIGS. 21a-d illustrate further images of the screw element 1101, firstly providing a guide to the actual size of the elements in FIG. 21a. In FIG. 21b illustrates the element 1101 wherein a separator ring 1135 may be provided, which can be inserted into a recess 1137 in the perpendicular face 1107 around the periphery of the bore 1103. The ring 1135 can be located within the recess 1137 and this allows the gap or width between adjacent elements to be adjusted according to the type of fibre or work required. For example, separator rings 1137 of varying thicknesses may be provided, allowing for gaps of varying sizes. The ring 1135 is shown in situ on an element 1101 in FIG. 21c.
[0129] Further, the thickness of the elements generally, and in particular as shown in FIG. 21d in relation to the elements 1101 can also be varied. Creating proportionally thicker elements 1101, for example, serves to create more pressure/work per rotation, in particular in a reverse screw configuration. Side grooves/serrations 1111 located on the parallel surface 1105 are provided extending in a single direction. Providing these with deeper, flatter grooves between the serrations 1111 serves to cheapen the overall production of the elements 1101 and increase the longevity of that surface, as the edges do not blunt so easily as with the more shallow and frequent grooves.
[0130] The elements of the present invention are formed from high abrasion-resistant steel, in order to maximise lifetime and provide longer wear.
[0131] The screw elements of the present invention may be formed or provided individually, as shown in FIGS. 1-4b. However, it is equally possible and sometimes preferable due to manufacturing costs to provide a number of elements as a group or cluster, as an assembly and an example of which is shown in FIG. 5. FIG. 5 illustrates a cross-section of a pair of complementary clusters of elements 501 that are located on adjacent screws in a screw processor. A number of clusters may be provided along the length of the screw assembly, and may be provided in varying sizes (i.e. the number of elements within the cluster may be varied). In between each set of clusters on the screw assembly, there may also be provided flow acceleration or restriction means, which may be provided in the form of spiral screw elements formed on the screw assembly that serve to increase or reduce the speed of flow of the material through the screw processor. The clusters of element 501 shown in FIG. 5 are, in this embodiment, effectively clusters of the individual elements 401 illustrated in FIGS. 4a-b. While it is possible to provide a single or multi screw assembly having a cluster of elements as depicted in FIG. 4a, located in a channel with textured interior walls, it is sometimes preferable to provide the screw arrangement as shown in FIG. 5 as it would enable more appropriate processing of the fibres/fibre pulp suspension. As can be seen, the serrations 513 formed on the perpendicular faces 507, 509 serve to complement adjacent elements such that as the same are rotated about their respective screw conveyor, the serrations 513 or other formations may intermesh smoothly with one another. Likewise, the formations or serrations 511 provided on the parallel surfaces of the elements 501 are formed to complement opposing serrations 511 or formations on a paired element. These may be designed specifically for a co-rotating screw arrangement or, conversely, for a counter-rotating screw arrangement. It will also be appreciated that some textured formations on the parallel surface 505 would be suitable for both co-rotating and counter-rotating screw arrangements.
[0132] Referring to FIGS. 6a-d, there is illustrated a pair of elements 601 which, in this embodiment, are elongated in length in comparison to previous embodiments and have a parallel surface 605 on which there is formed a series of protruding legs 615 extending outwardly from the surface 605. The legs 615 are provided around the periphery of the element 601 and along its length in a helical arrangement, as best illustrated in FIG. 6c. Further, in the illustrated embodiments, each leg 615 is provided with a substantially smooth face 617, and an opposing, textured face 619. In this particular embodiment, the face 619 is provided with a relatively wavy face, similar to that of a sine wave. However, it will be appreciated that alternative uneven formations/textures/teeth may be applied thereto. When paired on a twin screw assembly, it can be seen best from FIG. 6b that in a co-rotating arrangement as shown by arrows A and B, the legs 615 of the elements 601 will constantly intermesh one another in the region between the adjacent elements 601, thus providing a constant action on the fibres/fibre pulp suspension. Although not shown in FIGS. 6a-d, in further embodiments of the present invention, the legs 615, while acting as the texturing to the parallel surface 605 of the elements 601, may be provided with further texturing thereon so as to increase the gripping and/or cutting ability of the legs 615. Furthermore and as shown in, for example FIG. 6a, the elements are useful to achieve fibre shortening and can be arranged in various configurations, including forwarding and backpressure configurations, depending on source fibre type and required output.
[0133] An advantage of the embodiments of the present invention as shown in FIGS. 6a-d is that in providing the legs 615 with a textured face 619, the gripping and cutting action of the legs 615, when rotating, is vastly improved. The textured legs 615 help to grip the fibres/fibre pulp suspension and prevent them from being expelled between the elements 601 during the cut. Further, by providing the textured face 619 in a sine wave form greatly increases the actual cutting face length when compared to a straight length face. The curved surface 619 provides a more progressive shearing/slicing of the fibres/fibre pulp suspension compared to what would be a more sudden chopping action of a straight blade/cutting edge. This feature will improve the cut of the fibre and also reduce the stress imparted on the element 601. As described above and with reference to FIG. 6c, the legs 615 are arranged around the shaft/periphery of the element 601 in a helical manner. The texturing on the face 619 is provided arranged substantially parallel to the longitudinal axis of the element 601, and this arrangement allows the fibres/fibre pulp suspension to enter the screw assembly with less resistance when compared to the elements currently available in the prior art.
[0134] The various elements as shown in FIGS. 1-6d may be provided in various arrangements and combinations along at least part of the length of a screw assembly 700, as shown in FIGS. 7a-c. Close-ups of each individual pair of elements on the screw assembly 700 are illustrated in FIGS. 7d-f. As shown in FIGS. 7a-c, the screw assembly in this embodiment is provided in a twin-screw arrangement having numerous cutting/refining sections located along the length of the assembly. Depending on the particular element or combination of elements used in the screw assembly 700, the specific texture and size, and the method of use (torque/throughput/revs per minute), a carefully selected assembly of elements can offer an opportunity to reduce the fibre mass down to a nano scale. In this particular case, deliberate extreme defibrillation would be designed to result in the separation of the mass into individual fibres and produce connected 3 dimensional multi scale (macro / micro/nano) restructured fibres. FIG. 7g shows an example of a single screw assembly 700having processing sections 70, 75 along the longitudinal axis of the shaft. The embodiment illustrated in FIG. 7g provides a plurality of groupings of refining elements having a textured peripheral surface, wherein each of the groupings of refining elements forms a fibre modification section 70, 70, 70, 70 etc. The embodiment further includes a plurality of flow control elements, each of these groupings forming a fibre transport section 75, 75, 75, 75 etc., and located between each distinct fibre modification section. The fibre modification sections, and fibre transport sections are mounted on the extruder shaft 700in an alternating manner. FIG. 7g further provides an enlarged view of a fibre modification section 70 illustrating a plurality of, in this embodiment, mono-lobal elements such as for example any of those illustrated in FIGS. 2-4, or FIGS. 11-12 discussed below. The mono-lobal elements are arranged rotationally offset from each other by 180 such that every second refining element 7.1, 7.2 of each grouping is arranged in line. In some embodiments of the present invention, and as shown in FIGS. 7a-f, the screw assembly shown in FIG. 7g may be provided as a twin-screw processor, the shaft 700being paired with a second, complementary shaft having similarly arranged processing sections, such that the refining elements in each of the processing sections in the first shaft engage and/or intermesh with complementary elements on the section shaft.
[0135] In one embodiment, and with reference to the images of FIGS. 8a-h there is illustrated how the fibres created using the apparatus of the current invention can be defibrillated to different levels i.e from partial to full fibre length defibrillation. FIGS. 8a and 8c illustrates a bundle of lesser fibrillated fibres, FIG. 8b illustrates a bundle of mid-range fibrillated fibre; FIG. 8d illustrates an image of general defibrillated fibres; FIG. 8e illustrates a lesser fibrillated fibre; FIG. 8f illustrates a mixture of lesser and greater fibrillated fibres; FIG. 8g illustrates single micro fibres with nano fibrils and FIG. 8h illustrates a debrillated fibre end section. This variation is achieved by providing the appropriate combination of elements in the screw and thereby allowing the fibres to be held at specific elements in the textured element zones without destroying the fibre morphology. Particular arrangements of non-forwarding/holding elements are required to maximise the amount of fibre processing along with the placement of specific non-forwarding elements, compression elements and combinations thereof at strategic points along the screw.
[0136] The amount of defibrillation which is achieved can be based on any, or any combination, of the following features: the quantity and combination of large, medium and fine textured elements, with the large textured elements acting to separate the fibre clumps while breaking down the basic fibre walls, medium textured elements allowing the commencement of defibrillation and the beginning of nano-scale fibril exposure and the fine textured elements causing the fibrils to be spliced into nano-scale branches whilst still attached to the main core fibre.
[0137] In one embodiment the angle of the side wall of the elements relative to the shaft/housing in which the same is located may be selected to provide particular effects and therefore could be provided at an angle other than 90 degrees.
[0138] The direction of the texture on the element surfaces as the texture orientation affects the amount of work done on the fibre walls. The textures which are provided can be parallel or opposing (scissor like) and the fibre type and its sensitivity to mechanical processing determines the choice of orientation. The angle of slant between respective elements can also be used to control the aggression of the working by the elements on the fibres as can the selection of specific elements on opposing screws so that the elements, in combination, create a specific desired form of working on the fibres. The element to element texture size can also vary, depending on fibre shaping required, i.e. curl can be imparted to fibre structure. Using varying texture sizes in opposing elements along the shaft creates different end effects as can controlling the angle of textured elements on the shafts relative to each other and their position along the shafts. It is also possible to selectively interspace textured and non-textured elements (side and outer face texturing). It should therefore be appreciated that specific elements, and the textures thereon, can be selected to suit particular defibrillation requirements.
[0139] Typically therefore the defibrillating work which is performed allows the splitting of the outer layers of the fibre body into fibrils that ideally remain attached to the fibre core and this is achieved by the selection of suitable grades of textured elements in forms such as tri-lobals, bi-lobals and mono-lobals, with respect to the material being processed in order to enable the stripping of the fibrils from the fibre core in a controlled fashion. Preferably the fibre core is left largely intact with the fibrils hanging off along its entire length thus increasing the number of fibre bonding points as well as preserving a long core fibre, which is useful for reinforcement purposes. It is found that the Schopper Riegler (SR) values of the defibrillated fibres which are obtained in accordance with the use of the apparatus of the invention can be lower than the conventionally achieved values for N/FMC which are typically between 70 and 90. These relatively lower values are found to still be able to form relatively strong, lightweight dried material composites as a result of the relatively longer core fibres which are formed by the apparatus in accordance with the invention. These long core fibre composites are easier to dewater than M/NFC produced with conventional micro/nano fibre defibrillation techniques using refiners and other milling machines. This means that when there is a mat of the fibres most of any liquid will pass more quickly through the mat as the mat, whilst strong, is less dense and lighter with more air between the fibres than with conventional composite mats.
[0140] In accordance with the invention it is preferred that at least some of the elements are provided with textured surfaces which lie at substantially 90 degrees to the longitudinal axis of the shaft. It is found that these surfaces are valuable in improving fibre processing, as, when the elements are rotating they act as plate refining working zones and so provides a combination system of horizontal (standard extruder material direction) and vertical refining and can add up to of additional working surface to the screw profile while the length of the same remains the same hence ensuring that the passage of the fibre through the extruder is more productive and more energy efficient because the vertical refining produces less torque on the motor.
[0141] Different examples of groups of elements which can be used in complete screws are shown with reference to FIGS. 9a-d. In FIG. 9a there is shown a series of element groups 801 which are separated by flow control elements 803 in order to control the flow of the substance along the screw. In FIG. 9b there is shown element groupings 801 which are separated by a combination of flow control elements 803. In FIG. 9c there is illustrated the combination of flow elements 803 as in FIG. 9b and in this case there is provided a first group of elements 805 which are provided to allow for the forwarding of the material along the screw using textured elements, a second group of elements 807 which are flow neutral and a third group of elements 809 which are provided to allow for a reverse or backpressure arrangement of the textured elements.
[0142] FIGS. 9d and 9e illustrates the manner in which the elements 901 are provided selectively located in the housing 903 of the apparatus and located along a shaft 905. The elements can be positioned in a number of different ways with respect to the housing and each other so as to provide the required defibrillating and movement effect on the material which is introduced into and moved along the housing 903. For example, the elements may be provided in an in line arrangement as shown in FIG. 9d(i) and (iii) or in a stepped arrangement as shown in FIG. 9d (ii) and (iv). Also, as shown in FIG. 9d (iii) the elements can be provided in a standard offset arrangement along the respective shafts 905 or may be offset as illustrated in FIG. 9d (iv).
[0143] In FIG. 9e the elements 901 in (i) and (iii) are shown in-line linearly in (i) but are offset axially as indicated in (iii). In FIG. 9e (ii) and (iv) the elements are shown as being stepped linearly along the shaft as indicated in (ii) and offset axially as indicated in (iv).
[0144] FIGS. 10a-c illustrate variations in the combinations of elements which can be selectively positioned along the shaft with respect to the flow of material along the housing in the direction of arrow 911. In FIG. 10a, the arrangement illustrated is selected to be used in order to achieve complete defibrillation of short fibres. In FIG. 10b the screw design and element selection is with respect to the achievement of complete defibrillation of long fibres. In FIG. 10c the elements selection for the screw configuration is directed to achieving the complete defibrillation of short fibres along with the added provision of side feed capabilities 913.
[0145] Thus, these examples of screws with elements in configurations in accordance with the invention illustrate the manner in which the elements types and locations can be selected to provide specific screw configurations for the defibrillation of specific materials and thereby allow a bespokescrew design to be achieved.
[0146] When designing the same, reference is made to the type of fibres which are required to be formed, the targeted binding power and/or the final end product properties which are required.
[0147] With regard to the fibre types then for new, industrially processed, cellulose from hard/soft wood, field and other harvested plants these fibres tend to be more robust and longer than other forms of fibres discussed below and can therefore be used to provide high quality, pure (normally lignin/hemi-cellulose free) fibre for industrial and consumer paper- and board-based products. Such fibre requires that the screw profile must contain a substantial amount of textured elements which are graded from coarse to fine. These elements can then be arranged in patterns that respond adequately to non-pre-treated or to pre-prepared fibre. Pre-treatment and/or early stage in-line treatment is preferably carried out in order to soften the cellulose cell walls (weaken the fibril bonds to core fibre) which may, in one embodiment use steaming, typically with differential pressure. Pre-treatment is useful to preserve intrinsic fibre structure (reduce debris) and to save processing energy.
[0148] The figures show, by way of example, the interaction between elements that may be located on a pair of adjacent shafts of a screw assembly 700. However, in practice, a screw assembly may be provided having a plurality of shafts, for example, having 4, 6, 8, 10 or more shafts. The elements provided on each shaft will then be provided to intermesh with corresponding elements on adjacent shafts, to form the screw processor assembly. The shafts may be provided adjacent one another and substantially in the same plane, forming effectively a linear configuration of shafts, when viewing them front on. An example of this is shown in FIG. 13, wherein a screw assembly 1300 having four linearly aligned shafts 1305 is provided, with the elements 1301 located thereon. Alternative configurations are also possible, and envisaged in the present invention. For example, the shafts may be arranged parallel to, and located about, a central longitudinal axis of the screw processor. This provides the shafts in a planetary configuration, and which is shown in a front-on view in FIG. 14, wherein there can be seen an assembly 1400 having a plurality of shafts 1405 with elements 1401 thereon distributed evenly around a central axis of the screw processor. Once again, corresponding elements 1401 of adjacent shafts 1405 may intermesh with one another, and so, in order for the planetary configuration to function properly, an even number of shafts 1405 are required. This requirement is not as vital when providing the screw processor assembly in a linear configuration 1300.
[0149] FIGS. 16a-b illustrate further sections of a screw assembly which may be provided as forming at least part of the present invention, wherein elements 1601 of varying sizes are located along a first shaft 1605, and complementary elements 1601are aligned along a linearly parallel shaft 1605and arranged to intermesh with the first set of elements 1601. The constantly changing flow and uneven distribution of element sizes ensures that processing of the material which is injected through the processor is effective across all of the fibres in the material, maximising cutting/manipulation. In addition, further shafts 1605 may be introduced, having further elements 1601 down or upstream which complement elements on either of the shafts 1605, 1605. In another example of the present invention, some of the elements may be provided as cog-like members 1701, as shown in various forms in FIGS. 17a-c. Another feature of the cog-like members 1701 is that they may also be provided having one or more sub-elements in the form of smaller cogs 1731 located therewith. These may be located within a cavity of a housing 1733 in the cog 1701, shown in FIG. 17a and with a portion removed in FIG. 17b. In another example, the smaller cogs 1731 may be provided to interlock with one another and the shaft 1705 and interior wall of the primary cog member 1701, as shown in FIG. 17c. Such an arrangement allows further grinding of the material and fibres which are injected, and the fineness of the grinding can be selected as a result Such elements also multiply the pressurised grinding efficiencies while not building up any barrier pressure as material reaches these elements along the screw processor. FIGS. 18a-f illustrate further embodiments of how certain cog-like elements may be formed, in these examples, cogs 1801 may be provide with a plurality of apertures 1835 located in varying shapes and sizes, which allow a certain amount of the fibres or material being processed to pass through sections of the extruder undisturbed. FIG. 18a illustrates a cog element 1801 having a particular profile, and FIGS. 18b-f illustrate examples of further profiles which may be provided for such a cog element 1801.
[0150] In other examples of the present invention, in addition to the texturing of at least one face of the elements, some of the elements may be provided having varying shapes, in particular, some may be provided as having a substantially conical shape, at least one face of which may be textured with any or any combination of serrated, pinned, toothed, grooved and/or spiked formations.
[0151] As discussed above, some embodiments of the invention provide for section of the screw processor to include two or more linearly parallel shafts, whereby elements located on adjacent shafts may intermesh with one another. FIGS. 19a-d illustrate further examples of the present invention wherein, in the example of FIG. 19a, there may be provided a central shaft 1905 having an axis of rotation and a first element 1901 located thereon, and a plurality of further elements 1901, 1901, 1901 are subsequently provided, located on further shafts 1905, 1905, 1905 having axes of rotation which are perpendicular to the central axis 1905. Each of the additional shafts 1905, 1905, 1905 with respective elements 1901, 1901, 1901 thereon is arranged non-parallel with one another about the central axis 1905. Such an arrangement provides further grinding/milling etc. of the fibres in the material as it passes through the screw processor. Further arrangements of elements provided intermeshing with elements located on a non-parallel axis are illustrated in FIGS. 19b-d.
[0152] Finally, FIGS. 20a-b illustrate further examples of elements which may be provided on or along the screw processor. FIG. 20a shows a drill type arrangement wherein a central element 2001 on a central shaft 2005 is surrounded by further elements 2001 on parallel shafts 2005, creating a pepper mill type of refining of the fibres as the material passes through. FIG. 20b illustrates elements which may be provided in the style of drill-bits 2001, which rotate about their axis of rotation to manipulate the fibres.
[0153] FIGS. 22a-c illustrate a further type of element 2201 and their arrangements along a shaft of the screw processor. The elements 2201 are provided of a shape wherein the circumference of the elements 2201 follow the path of a substantially circular sine wave. That is to say, about the circumference of the element 2201 there are provided an equal number of peaks 2203 and troughs 2205 in the surface thereof. In the figures shown, the elements 2201 have eight peaks 2203 and eight troughs 2205, although it will be understood that this number can be varied depending on the particular requirements of the apparatus. The elements 2201 may be provided on first and second parallel screws and arranged to engage or intermesh one another in a complementary fashion, such that the peaks 2203 of a first element 2201 on a first shaft are arranged to engage and/or intermesh the troughs 2205of a second element 2201on a second shaft, and vice versa. Typically, two or more elements 2201 are provided adjacent and/or abutting one another along a shaft or screw of the screw processor, and are arranged to be rotationally offset from one another. Typically, said offset is provided to be between approximately 11.25 and 22.5. A similar such arrangement can then be provided on a second shaft or screw, permitting intermeshing and/or engaging of first and at least second series of offset elements 2201 and 2201.
[0154] FIG. 23a illustrate how the exterior surface 2207 of the element 2201 about its circumference is also provided to be textured. This is shown also in FIG. 23c.
[0155] Further, FIG. 23b illustrates how the sharpness of the peaks 2203 and troughs 2205 of the elements 2201 may be varied according to specific requirements. That is to say, the peaks may be provided to be more or less pronounced, with shallower 2207a or deeper 2207b troughs, depending on the specific needs and requirements of the apparatus.
[0156] In further embodiments, as shown in FIG. 24, groups of elements 2201 may be provided, rotationally inline, with an abutting group subsequently offset. The two groups are then arranged to intermesh/engage with similarly arranged groups of elements 2201on a second shaft.
[0157] Such arrangement ensure that the fibres can be trapped in the troughs 2205 and compressed between opposing or intermeshing elements and/or between the peaks 2203 and the interior of the extruder barrel walls (not shown).
[0158] At least part of the exterior surface of the elements of the present invention are provided to be textured. FIG. 25 illustrates a grouping of aligned tri-lobal elements 2501, wherein the external surface 2503 about the periphery of those elements is provided to be textured. Tri-lobal elements are already known, however, no such elements are known in the art which are tailored to the requirements of defibrillating fibres and having textures or texturing provided on any of the external surfaces thereof-known versions all have completely smooth surfaces. Providing textured surfaces has specific advantages: [0159] i. Compression areas are smaller than with the open side of cam type elements, therefore increasing fibre manipulation potential. Therefore, in contrast to the current smooth outer surfaces of current Tri-Lobals, textured surfaces (of various types) can substantially multiply the fibre defibrillation effect on the fibres themselves. [0160] ii. Individual element production as opposed to multiple blocks (most common) allows for specific rotation of the elements to create configurations that either express, hold or retain the fibre mass depending on the fibre fibrillation and type required.
[0161] In some embodiments of the invention and as shown in FIGS. 26a-b, groupings of tri-lobal elements 2501 may be provided along a shaft wherein adjacent or abutting elements 2501 are provided to be rotationally offset from one another. Since the elements are tri-lobal, the preferred angle of offset is approximately 60 as shown in the figures. Further, where two parallel shafts are provided, i.e., in the form of a twin screw, the grouping of offset elements 2501 on a first shaft are arranged to intermesh with a complementary grouping of similarly offset elements 2501on a second shaft. The exterior surface of such elements, about the periphery of the same are provided to be textured and can be done so in a number of ways, such as in the form of serrations, ridges, or steps along the surface, and shown in more detail in FIGS. 28a-c. In some embodiments, the either or both of forward or rearward faces of the tri-lobal elements 2501 may be provided to be at least partially textured.
[0162] The surfaces of the elements and or interior walls of a barrel of the apparatus of the present invention, in which the screw or shaft is located may be hardened and/or coated in order to make them more durable and extend their wear characteristics. Typically, such surfaces may be hardened and/or coated with any of the following: tungsten carbide; tungsten carbide and cobalt matrix; tungsten carbide and nickel matrix; tungsten carbide micron and nanometre particles, and cobalt matrix; silicon carbide plating; and/or nickel silicon carbide plating.
[0163] With regard to fibres which are post consumer and post industry recycled fibres, such as waste paper and cellulosic packaging materials and fibres from agricultural fibre crops such as beet and residual sources such as silage, these fibre products often contain a variety of industrial additives and/or other components that determine how, in the M/NFC process, the textured elements should be arranged. Aspects to be considered includes minerals which are present, such as silica/chalk/dyes and pigments/other fillers which impart wear on the element surfaces and increase the rate of dewatering. Screw configurations/materials should respond to the quantity and role of these additives. Substantial residence time will increase element wear but simultaneously assist in fibre defibrillation. The presence of Lignin and/or hemi-cellulose can act as a lubricant during processing, thereby requiring brake or holding pattern elements to ensure work is done in the subsequent textured zones. When the lignin content is high, it may affect SR levels and may also reduce the need for high defibrillation levels because the lignin acts as a binder in the final product.
[0164] These fibres tend to be shorter and require less work to be performed on them and so typically elements with a finertexture can be used on the screw.
[0165] In one form of pre treatment of the fibres, an alkali such as Calcium Oxide can be added.
[0166] It is possible to add minerals and other additives such as colour, polymers, waterproofing agents, to the material during the defibrillation process and the additives are retained in the material by the three-dimensional fibre matrix. The defined targeting of the input of additives at key points along the screw can be a major advantage of precise textured element screw profile designs and larger particle additives, for instance minerals, can be introduced after large texture element treatment, whereas finer suspension type additives can be added during processing after medium to fine elements.
[0167] Typically the temperatures at which the apparatus is operated is required to be controlled in order to avoid overheating and avoid the risk of hornification (closing/knotting of the fibrils and main fibre) prematurely. Typically, the fibre should emerge from the extruder in a state where it can be used in an open three-dimensional condition so that the multiple bonding points are available for use in the end product. Placement along the screw as well as the shaft to shaft and element-to-element relationship of the textured elements can be used to control the heat generated in any given element type zone.
[0168] In one embodiment the use of saw tooth cluster-block elements in a forwarding or back-pressure arrangement is an extremely effective method of fibre size control. These elements allow the use of a feedstock fibre size measured in millimetre lengths rather than sizes approaching dust. The proximity of the saw-tooth spigots to each other and to the corresponding/opposite element on the shafts can be varied to achieve a shorter or longer fibre length for further processing further along the screw profile. Forwarding elements are less aggressive than backpressure elements; both types can be used in a screw profile depending on the fibre type and end fibre condition required. Exclusive use of the saw tooth cluster-blocks is not limited to the role of fibre reduction as they can be used to further reduce/condition fibres which have been subject to less working elements at an early stage i.e. use of various transport elements either forwarding or reverse. The saw tooth cluster-block elements can also be used to distribute an additive or additional fibre that is fed into the extruder at a later stage.
[0169] In one embodiment steam injection can be provided at locations along the screw apparatus in order to optimise the defibrillation process.
