Fiber extraction method

Abstract

The invention discloses a method for obtaining long flexible textile fibers from palm tree species. The method includes a combined step of treating the stem by applying an alkali solution to remove lignin, wherein the alkali solution may be a sodium hydroxide solution. The non-cellulosic matrix is then mechanically removed and fibrous vascular bundles are fiberized by scraping the treated stem using a blunt blade. The step may include soaking the stem in an aqueous alkali at a temperature t in the range of t =-4.82 (c * d) + 92.3 DEG C +-12.5 DEG C, where c is the concentration of sodium hydroxide (expressed in%, or equivalent pH), and d is the treatment duration (in hours).

Description

[0001] Field of the Invention The present disclosure relates to a fiber extraction method and more particularly, but not exclusively, to extracting long textile fibers from palm midribs and rachises, such as fibers from the date palm (Phoenix dactylifera). Background Art

[0002] The date palm is cultivated primarily in the Middle East and North Africa. Typically, more than 1 million hectares are harvested worldwide. Globally, the byproduct of date palm pruning is estimated to be approximately 5 million tonnes (air-dried weight) per year in the form of midribs, rachises, leaflets and sheaths. These materials are generally considered agricultural waste.

[0003] Previous attempts to extract fiber from the midrib and rachis of the date palm were limited to grinding it into small particles containing a high percentage of non-cellulose impurities. These are typically used to make worktops and building panels, such as particleboard or medium-density fiberboard (MDF), or as fillers in synthetic plastic materials.

[0004] Some of them are described in the documents mentioned below.

[0005] Prior art US Patent US 10 767 267 (United Arab Emirates University).

[0006] International patent application WO 2020 / 139088 (Sultan Qaboos University).

[0007] Canadian Patent Application CA 2 504 227 (Soil Sub Technologies Pte Ltd).

[0008] US Patent US 10 655 009 (United Arab Emirates University).

[0009] Russian patent application SU 620517 (TSNII PROMY LUBYANYKH VOLOKON) describes a method for obtaining fibers from bast using a scouring process to produce fibers with improved spinnability.

[0010] These attempts failed to extract long textile-grade fibers.

[0011] An object of the present invention is to make more valuable the large amount of agricultural residues produced by plantations of palm trees, especially date palm, and to extract long textile fibers from the midrib and rachis stems. Summary of the invention

[0012] According to a first aspect of the present invention, there is provided a method of obtaining fibres from palm tree species, the method comprising the steps of: a) treating the stems to remove lignin by applying an alkaline solution, and b) scraping the treated stems to mechanically remove non-cellulosic matrix.

[0013] Ideally, the fibrovascular bundles are also fibrillated, for example by applying a blunt spatula.

[0014] The present invention mechanically removes non-cellulosic matrix by extraction and fibrillates the fiber vascular bundle to clean the fiber and improve spinnability using a combination of chemical and mechanical methods.

[0015] In one embodiment, the present invention is used to extract fiber from the petiole of a date palm. The petiole (midrib) of a date palm is primarily composed of thick bundles of vascular fibers that extend throughout the cross section of the petiole and are embedded in a matrix of lignin and hemicellulose. Palms are classified as monocots and contain a variety of fiber vascular bundles of varying sizes. However, it will be appreciated that the method can be used with other types of palms, as described below.

[0016] Bast fibers are dicots and consist of pure fiber bundles. They tend to be uniform in size. Due to the inherent structural differences between leaf fibers and bast fibers, the technical challenges of extracting vascular bundles are significantly different from extracting pure fiber bundles.

[0017] In some embodiments, the alkaline solution is a sodium hydroxide solution.

[0018] Preferably, the method comprises a step of soaking the stems in an alkaline solution at a temperature t, wherein t is in the range of t = -4.82 (c x d) + 92.3°C ± 12.5°C, wherein c is the concentration of sodium hydroxide (expressed in %), or equivalently pH, and d is the duration of the treatment in hours. The stems are then scraped by applying a blunt scraper.

[0019] In some embodiments, the method steps include soaking the stem material in an alkaline solution at a temperature t, where t ranges from t = -4.82(cxd) + 92.3°C ± 6°C.

[0020] Optionally, the method comprises an initial step c) of separating the leaflets from the palm fronds.

[0021] In some embodiments, the method includes the prior step d) stripping the outer layer of the palm stem to remove waterproof wax and pectin layers that resist treatment.

[0022] The method may comprise the further previous step e) slicing the stem longitudinally to reduce its thickness and to ensure uniform treatment over the thickness of the stem.

[0023] In the claims, the term "stem" includes the palm midrib and the inflorescence axis.

[0024] According to a second aspect of the present invention, there is provided a method of obtaining fibre from a palm tree species, the method comprising the steps of: soaking the fibre stems in a pool of water at an ambient temperature of 20°C to 45°C.

[0025] Soaking can be done in direct sunlight or in the shade and can last from 1 to 16 weeks.

[0026] According to a third aspect of the present invention, there is provided a method for obtaining fiber from a palm tree species, comprising the steps of placing a midrib / inflorescence axis slice in hot water at 80°C to 100°C at normal atmospheric pressure for a period of 3 to 8 hours.

[0027] Alternatively, the midrib / axis sections are placed in a pressurized vessel at a temperature of 100 °C to 120 °C and a pressure of 0 - 1 bar for a period of 1 to 3 hours.

[0028] Preferably, the midrib / axis sections are peeled prior to sectioning.

[0029] According to a fourth aspect of the present invention, there is provided a fiber product derived using the above method.

[0030] The fiber product produced according to the method can be used to make or incorporate into a large number of different articles or products, including: articles of clothing or footwear; sheets of flexible material; articles for automotive or construction use (such as panels or insulation boards) or ropes or twine.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described with reference to examples and the following drawings, in which: Figure 1 shows the midrib of a date palm (upper image) and the axis of the inflorescence (lower image), respectively; Figure 2 shows three scanning electron microscope (SEM) micrographs indicating the building blocks of the midrib of the date palm; Figure 3a shows fiber damage and breakage due to non-optimized processing; Figure 3b shows the pure and intact midrib and inflorescence axis fibers obtained by the optimized process steps; Figures 4 and 5 show examples of fibers produced after applying the extraction method; FIG6 shows a diagrammatic representation of method steps according to an example of the present invention; Figure 7 shows an example image of a gypsum block reinforced with treated midrib fibers of date palm; FIG8 shows an example image of a Date Palm Midrib molded pulp food bowl or plate; FIG9 shows an image of an insulation mat formed from treated date palm midrib fibers; and FIG. 10 shows example images of composite panels formed from treated midrib and rachis fibers of date palm.

[0032] Detailed Description of the Preferred Embodiments Figure 1 shows the midrib of a date palm (top) and the rachis of the inflorescence (bottom).

[0033] The midrib and inflorescence axis fibers of the date palm are considered to be leaf fibers similar to sisal, abaca, pineapple, and banana fibers. In general, leaf fibers are monocots and contain multiple fiber vascular bundles of varying sizes. Most fiber bundles are round or oval in shape with single or multiple vascular spaces, and they are composed of elemental fibers that can have multiple cell walls and a central lumen, as shown in Figure 2 Figure 2 shows a scanning electron microscope (SEM) micrograph showing the building blocks of the midrib of the date palm.

[0034] Conventional fiber extraction routes used for other leaf fibers (sisal, banana, abaca or pineapple), such as scraping-washing-brushing, cannot be applied in the case of fiber extraction from the midrib and rachis of date palm. This is because the midrib and rachis are thicker, have a lower moisture content, and are covered with a tough layer of wax and pectin. Therefore, any attempt at direct scraping will result in pulverization rather than extraction.

[0035] Furthermore, there are two major challenges in extracting long textile fibers from the midrib and rachis of date palm. First, the vascular fiber bundles are embedded inside the midrib or rachis and surrounded by a complex natural adhesive matrix consisting of lignin and hemicellulose, which makes it difficult to extract pure fibers without destroying or damaging the fibers. Second, the vascular fiber bundles are thick and hollow, lacking sufficient flexibility to be processed into any textile form. Therefore, the fibers tend to break when bent or twisted.

[0036] In an exemplary method, a process is provided to delignify and fiberize subsequent fiber vascular bundles into pure long and flexible elemental fibers or smaller bundles without causing any damage to the fibers during the extraction process.

[0037] method Initial preparation In the initial step, leaflets are separated from freshly picked green date palm leaves, either manually using hands, knives, or using a mechanized system with blades to peel the leaflets to obtain the midribs, which are then tied for further processing.

[0038] For inflorescence axis stems, cut the top branchlets from the fresh green inflorescence using a knife, hand saw or mechanized saw.

[0039] Skinning Stripping away the outer wax and pectin layers surrounding the midrib and axis of the stem is an important step to ensure efficient extraction, as the wax and pectin layers act as a waterproof membrane, preventing downstream wet treatments from penetrating and reacting with the inner core of the midrib and axis of the stem.

[0040] Peeling can be done mechanically, by scraping or stripping blades, or by abrasive rollers or sandpaper or wire brush rollers or drums. Peeling can also be done thermally, using singeing, where a direct flame source is used to burn off the wax and pectin layers. Alternatively, a high intensity heat source, such as a laser, can be used.

[0041] Debarking can be achieved chemically, using solvents including methanol, hydrochloric acid, and other commercial solvents for wax and pectin dissolution.

[0042] slice Slicing is the process of reducing the thickness of the midrib or rachis stem and splitting it into smaller longitudinal strips of regular or irregular cross-sectional area, ideally not exceeding 3 cm2. The slicing process is very important to ensure that downstream wet processing has a uniform effect and to avoid shell processing problems, where the outer shell of the strip is processed but the inner core is not.

[0043] Slicing can be done manually using a knife, or using a mechanized system where the midrib or rachis is fed into a machine with conveyor rollers that force the stem through the blades of a slicing die of predetermined cross-sectional shape and size. Slicing can also be done by mechanized pressure rolling where the midrib and rachis are split into irregular longitudinal strips.

[0044] Main treatment The processing of the midrib or rachis slices is a critical step in the fiber extraction process. The main purpose of the processing is to weaken or break the bonding effect of the non-cellulosic matrix composed of lignin and hemicellulose.

[0045] Treatment can be achieved in a variety of ways and under different conditions.

[0046] According to one embodiment, the midrib or inflorescence axis sections are treated with alkali.

[0047] In one example, the method is to subject the midrib / axis sections (e.g., after peeling and sectioning) to a mild alkaline treatment, such as using a low concentration sodium hydroxide solution <5%. Here, the midrib or axis sections can be immersed in a bath containing sodium hydroxide solution, with the bath (solution) ratio ideally not less than 10:1.

[0048] To ensure uniform treatment, the sodium hydroxide solution must be continuously stirred or circulated by a stirrer or stirring rod or a circulation pump. Optionally, a wetting agent can also be added to the bath to ensure uniform treatment. Treatment can be carried out at various combinations of duration, temperature and sodium hydroxide concentration.

[0049] The treatment results in the removal of surface impurities and the fibrillation of the vascular bundles, which can be achieved, for example, by increasing any of the three treatment conditions: concentration, temperature, and duration. However, it was found that increasing the sodium hydroxide concentration and / or the treatment temperature increased the purity of the extracted fiber and resulted in more fibrillation. In addition, it was noted that increasing the temperature had a more significant effect than increasing the sodium hydroxide concentration; because increasing the temperature tends to make the reaction more violent.

[0050] On the other hand, increasing the treatment duration had a less pronounced effect on the removal of surface impurities but a more significant effect on fiberization. Further increasing the severity of the treatment conditions may lead to overtreatment of midrib and rachis fibers, with the risk of damaging and breaking the fibers, as shown in Figure 3a.

[0051] Therefore, in a preferred example, the processing conditions are optimized to extract pure and intact midrib and rachis fibers, as shown in Figure 3b.

[0052] In one example, this is achieved by treating the midrib and rachis sections at between 65°C and 110°C, preferably further between 75°C and 100°C, while using low concentration sodium hydroxide 0.5% to 1.5%, preferably for a period of 0.8 hours to 1.2 hours.

[0053] More preferably, the concentration is between 0.9% and 1.1%, for a short duration of, for example, 30 minutes to 2 hours, preferably about 1 hour. However, it will be appreciated that longer treatment times may be selected with a corresponding reduction in sodium hydroxide concentration and / or treatment temperature to save energy.

[0054] Alternatively, this method can be achieved by treating midrib and inflorescence axis sections at room temperature, using a higher sodium hydroxide concentration (5%) for a longer duration (3 h).

[0055] Thus, any parameters of time and / or base strength and / or temperature may be maintained.

[0056] Typically, the treatment temperature (in degrees Celsius) is preferably in the range of -4.82(c*d) + 92.3°C ± 12.5°C, or preferably -4.82(c*d) + 92.3°C ± 6°C, where "c" is the sodium hydroxide concentration (in %, or equivalent), and "d" is the treatment duration (in hours).

[0057] Other bases may be used, the term "equivalent" being understood as solutions having the same pH as the sodium hydroxide (NaOH) solution.

[0058] Other alternative treatments include hydrothermal treatment, which is an alternative to treatments using alkaline substances. In one example, the midrib / axis slices (e.g. after peeling and slicing) are placed in hot water at 80 °C to 100 °C at normal atmospheric pressure for 3 to 8 hours. Alternatively, the peeled and sliced ​​midrib / axis slices are placed in a pressurized container at a temperature of 100 °C to 120 °C and a pressure of 0 - 1 bar for 1 to 3 hours.

[0059] Another alternative treatment involves water immersion, which is also an alternative to the treatment using alkaline substances. In one example, the method involves immersing the midrib / axis sections (e.g. after peeling and slicing) in a pool of water at an ambient temperature of 20 °C to 45 °C, in direct sunlight or in the shade, for a period of 1 to 16 weeks.

[0060] Scratching After processing the midrib and inflorescence axis sections, the sections became swollen and the non-cellulosic matrix partially dissolved. However, in this case, the matrix still surrounded the vascular fiber bundles and elemental fibers. Therefore, the scraping process is a key step for mechanical separation of the non-cellulosic matrix (delignification) without causing any damage to the fibers.

[0061] Furthermore, the scraping action splits (fibrillates) the thick fiber vascular bundles into finer bundles or fibers and eliminates the hollow contents, resulting in long, thin, flexible textile fibers.

[0062] The scraping action can be performed using a blunt scraper that reciprocates along the length of the midrib and inflorescence axis slice. It can also be performed using a rotating drum (debarker) with multiple blunt scrapers that rotate against a fixed beating plate. In this case, the midrib and inflorescence axis slice is fed into the gap (<2 mm) between the rotating scraper and the fixed roller and is scraped one or more times from one or both ends. It is important that the scraping is performed while the treated slice is still wet.

[0063] Cleaning and / or Neutralization The fiber must be neutralized after extraction by washing with water to lower the pH, and then soaked in a 5% acetic acid solution after extraction to ensure that the fiber reaches a pH of approximately 7. After neutralization, the fiber is washed with water to remove any remaining impurities.

[0064] dry After washing, the fibers are dried to a moisture content of less than 20%, preferably less than 15%. The first step in drying is to remove as much water as possible by roller pressing, or by centrifugal dehydration using a mechanized drying system.

[0065] The second step of drying is to hang the fibers in the open air for several days, depending on the ambient conditions, or in an oven at 50 °C until the moisture content drops below 15%.

[0066] scrub After washing and drying, the fibers are held together by hydrogen bonds. To open the fibers, they must be beaten or brushed. Beating and brushing are done by a rotating drum with multiple blunt blades or short metal combs, where the fibers are held from one end and fed into the gap between the rotating drum and a flat metal surface, where they are brushed one or more times from one or both ends.

[0067] The fibers obtained at the end of the extraction method are shown in FIG. 4 .

[0068] Referring to Figure 6, there is shown a diagrammatic representation of the above method steps. Additional debonding steps may be performed, as detailed below.

[0069] Degumming To further refine the fiber, for example to reduce any non-cellulose impurities and reduce the cross-sectional area of ​​the fiber, a degumming step may be applied. Degumming is ideally performed after the scrubbing step and may be performed using degumming chemicals or enzymes.

[0070] One advantage of degumming is that it helps reduce any non-cellulosic impurities and reduces the cross-sectional area of ​​the fiber, resulting in finer, softer fibers.

[0071] In one example, degumming is achieved by treating the extracted fiber at between 65°C and 110°C. Preferably, the treatment temperature is between 75°C and 100°C, while using low concentrations of sodium hydroxide 1% to 3%, low concentrations of hydrogen peroxide 0.1% to 0.3%, and 0.3% to 0.9% sodium silicate, and optionally 0.3% to 0.9% ethylenediaminetetraacetic acid (EDTA), preferably for a duration of 2 hours to 4 hours. After chemical degumming, the fiber is neutralized in a 5% acetic acid solution and then washed with water.

[0072] In another example, this is achieved by treating the extracted fiber at between 50 °C and 65 °C, while using laccase with an activity of 2000 U / g and acid xylanase with an activity of 100,000 U / g, in a buffer solution at pH 4.8, preferably for a period of 6 hours to 10 hours. After degumming in the enzyme solution, the fiber can be scoured with a 2% soda ash solution at 80 °C for 2 hours to remove residual gum. After scouring, the fiber is neutralized in a 5% acetic acid solution and then washed with water.

[0073] Technical Data

[0074] Table 1 shows the average properties of long fibers extracted from the midrib and inflorescence axis stems of date palm using the above method.

[0075] For example, the method can also be used to extract long textile fibers from the midribs of other palm species, including but not limited to Washingtonia robusta, Elaeis guineensis, Coconut palm (Cocos nucifera), Doum palm (Hyphaene thebaica), Acai palm (Arecaceae), and Sugar palm (Borassus flabellifer). It can also be applied to other agricultural residues in the form of long stalks, including but not limited to bamboo.

[0076]

[0077] Table 2 shows the average properties of long fibers extracted from the midrib of Elaeagnus oleifera, Tomo palm, and Washingtonia palm.

[0078] Sodium lignin by-product According to another aspect of the present invention, there is provided a sodium lignin byproduct derived from the above method by treating the midrib and inflorescence axis stem slices with sodium hydroxide alkali.

[0079] The sodium ligninate by-product produced according to the process can be used to make or incorporate into a number of different items or products, including plasticizers for cement and concrete, and adhesives for wood panels and paper.

[0080]

[0081] Table 3 Chemical composition analysis of sodium lignin in the midrib of date palm Dehulled Cellulose Fluff By-Product The cellulosic fluff byproduct may be formed at the midrib and rachis peeling stages. The cellulosic fluff byproduct produced according to the method may be used to make or incorporate into a number of different articles or products, including absorbent fluff for baby diapers and feminine hygiene pads, and in the manufacture of paper pulp.

[0082]

[0083] Table 4 Chemical composition analysis of cellulose hairs in the midrib of date palm A method of making gypsum reinforced with date palm midrib and rachis fibers is now described.

[0084] In one example, the midrib and inflorescence axis stem sections are treated with an alkaline solution of 1% sodium hydroxide at 70 °C for 75 to 180 minutes. The sections are then scraped using a rotating drum (debarker) with multiple blunt scrapers that rotate against a fixed roller with a gap of 0.4 to 0.7 mm to extract the long fiber bundles. The extracted fibers are then washed and neutralized in a 5% acetic acid solution for 1 to 30 minutes. The neutralized fibers are then washed with water, dehydrated using squeeze rollers, and dried to reduce the moisture content to 15%.

[0085] The dried fibers are then scrubbed using a rotating drum with a dull metal blade. The scrubbed fibers are then incorporated into a wet mixture consisting of 2 parts of gypsum and 1 part of water, with a weight percentage of 10% to 20% of date palm midrib or inflorescence axis stem fibers and 90% of gypsum powder. The gypsum reinforced with date palm midrib or inflorescence axis stem fibers can be cast into a mold or slab. The casting is then dried at room temperature and begins to set after 30 minutes.

[0086] The addition of date palm midrib fibers to gypsum enhanced its flexural properties, reaching an average modulus of rupture of 1.47 MPa according to ASTM C293, which is 21% higher than gypsum reinforced with sisal fibers. In addition, the addition of date palm midrib enhanced the compressive strength of gypsum, reaching 1.87 MPa according to ASTM C109.

[0087] Gypsum reinforced with midrib fibres from the date palm can be used in building applications including ceiling tiles, cornices, drywall and facades.

[0088] A method for pulping fibers extracted from the midrib and rachis of the date palm is now described.

[0089] In one example, the midrib and inflorescence axis stem sections are treated with an alkaline solution of 5% sodium hydroxide at room temperature for 3 to 5 hours. The sections are then scraped using a rotating drum (debarker) with multiple blunt scrapers rotating against a fixed roller with a gap of 0.4 to 0.7 mm to extract the long fiber bundles. The fibers are then chopped using a rotary cutter into lengths that typically range from 1 to 5 cm.

[0090] The chopped fibers are then pulped using a hydraulic pulper at 50 - 400 rpm and minimum clearance for a duration of 10 to 90 minutes to produce pulp. The pulp is then optionally bleached using 2% hydrogen peroxide at 80 °C for 30 - 120 minutes to whiten the pulp, or sodium hypochlorite or other bleaching agents may be used. The pulp may be mixed with an antimicrobial agent and stored for several days, or may be immediately formed into any desired shape, including sheet form.

[0091] The pulp or sheet is then dewatered by squeezing rollers and dried to less than 10% moisture. Date palm midrib and inflorescence axis pulp has properties equivalent to bamboo pulp and represents a new non-wood pulp source for papermaking and molded fiber packaging, including food packaging.

[0092] Examples of acoustic insulation panels are described in a paper authored by EA Darwish, Mohamad Midani, titled “Potential of Date Palm Midrib-Based Textile Acoustic Panels for Sustainable Interior Design” (Ain Shams Engineering Journal, Vol. 14, No. 6, 2023, 102100, ISSN 2090-4479, https: / / doi.org / 10.1016 / j.asej.2022.102100).

[0093]

[0094] Table 5 Chemical composition analysis of midrib pulp of date palm A method of making thermal and acoustic insulation felts from date palm midrib and rachis fibers is now described.

[0095] In one example, midrib and rachis stem sections were treated with an alkaline solution of 5% sodium hydroxide at room temperature for 3 to 5 hours.

[0096] The slices are then scraped using a rotating drum (debarker) with multiple blunt scrapers rotating against a fixed roller with a gap of 0.4 to 0.7 mm to extract the long fiber bundles. The extracted fibers are then washed and neutralized in a 5% acetic acid solution for 1 to 30 minutes.

[0097] The neutralized fibers were then washed with water, dewatered using squeeze rollers, and dried to reduce the moisture content to 15%.

[0098] The dried fibers are then brushed using a rotating drum with dull metal blades. The fibers are then chopped into lengths of 5 to 7 cm using a rotary cutter.

[0099] The shredded date palm midrib and rachis fibers are then mixed with thermoplastic binder fibers, which may be polypropylene, polyester, polylactic acid, polyhydroxyalkanoate, or any combination thereof.

[0100] In one embodiment, the date palm midrib fiber is mixed with the low melting point polyester, wherein the dry weight mixing ratio is 90% date palm midrib fiber and 10% low melting point polyester fiber.

[0101] The mixed fibers are then air blown onto a forming conveyor to form a high loft fiber mat, where the blowing and conveyor speeds are controlled to achieve the desired mat density. The mat is then heat set at the desired thickness and density combination, where heat setting is performed using hot air at 160 to 180 °C through an oven or using a heated calender.

[0102] The felt may be impregnated with flame retardants including ammonium salts.

[0103] Finally, the felt is cut into the required size using a rotary cutter. Insulation felt made from midrib or rachis fibers of the date palm has low thermal conductivity and high acoustic absorption coefficient and is suitable for use in the construction, automotive and aviation sectors.

[0104] Alternatively, the fibers may be mixed with other materials, such as gypsum, to enhance the strength of a composite product such as a felt or cutting board. In a preferred embodiment, the fibers may be aligned in a particular direction, or alternating plies of fibers may be sandwiched together or stacked one on top of the other to improve the stiffness and / or strength of the composite building assembly.

[0105]

[0106] Table 6 shows the average properties of date palm midrib fiber insulation felt with a density of 150 kg / m³ Examples of thermally insulated cutting boards are described in a paper by EA Darwish, Ayah Salem Eldeeb, and Mohamad Midani titled “Housing Retrofitting for Energy Efficiency: Enhancing Indoor Thermal Comfort Using Modular Date Palm Midrib Cladding” (Ain Shams Engineering Journal, 2023, 102323, ISSN 2090-4479, https: / / doi.org / 10.1016 / j.asej.2023.102323).

[0107] A method of making a polymer composite panel reinforced with date palm midrib or rachis fibers is now described.

[0108] In one example, midrib and inflorescence axis stem sections were treated with an alkaline solution of 5% sodium hydroxide at room temperature for 3 to 5 hours. The sections were then scraped using a rotating drum (debarker) with multiple blunt scrapers rotating against a fixed roller with a gap of 0.4 to 0.7 mm to extract the long fiber bundles.

[0109] The extracted fibers are then washed and neutralized in a 5% acetic acid solution for 1 to 30 minutes. The neutralized fibers are then washed with water, dehydrated using squeeze rollers, and dried to reduce the moisture content to 15%. The dried fibers are then brushed using a rotating drum with a dull metal blade. The fibers are then chopped into lengths of 5 to 7 cm using a rotary cutter. The chopped date palm midrib and inflorescence axis fibers are then mixed with thermoplastic binder fibers, which can be polypropylene, polyester, polylactic acid, or any combination thereof.

[0110] In one embodiment, date palm midrib fibers are blended with polypropylene in a dry weight blend ratio of 50% date palm midrib fibers and 50% polypropylene fibers. The blended fibers are then carded to form a uniform web and cross-laid to ensure uniform distribution of the fibers in the machine and cross directions.

[0111] The carded cross-lapped nonwoven web is then felted using a needle punching process, wherein barbed needles penetrate the web to consolidate the web by entangled fibers, thereby forming a web having an area density of 1,200 to 2,000 grams per square meter.

[0112] In one embodiment, the felted nonwoven web is heat pressed at 183°C for 15 minutes at a pressure of 15 MPa and then cooled before demolding.

[0113] In another embodiment, the felted nonwoven web is thermoformed wherein the nonwoven web is heated in a convection or conduction oven at 160°C to 180°C for 10 to 20 minutes and then pressed using a cold mold at 15 MPa for 5 minutes before demolding.

[0114] Date palm midrib fiber reinforced composite is a lightweight, recyclable and partially biodegradable composite material that can be used in non-structural applications such as automotive door panels, trunk linings, parcel shelves, trims and other interior components.

[0115] Examples of composite panels are described in a paper by Elseify, LA, Midani, M., El-Badawy, AA, et al., titled “Benchmarking of automotive nonwoven composites from midrib and rachis fibers of date palm with commercial leaf fibers” (Biomass Conv. Bioref., 2023, https: / / doi.org / 10.1007 / s13399-023-03910-w).

[0116]

[0117] Table 7 shows the average properties of polypropylene (PP) composites reinforced with date palm midrib and rachis fibers.

[0118] It will be appreciated that modifications to the above described embodiments may be made without departing from the scope of protection defined in the claims.

Claims

1. A method for obtaining fiber from palm tree species, the method comprising the steps of (a) treating the stems by applying an alkali solution to delignify, and (b) mechanically removing non-cellulosic matrix and fibrillating the fiber vascular bundles by scraping the treated stems with a scraper.

2. A method for obtaining fiber according to claim 1, comprising step (w) treating the stems by water impregnation to remove lignin, carried out at a water temperature of 20°C to 45°C.

3. The method according to claim 1 or 2, wherein the alkaline solution is a sodium hydroxide solution.

4. A method according to any one of claims 1 to 3, wherein step (a) comprises soaking the stems in the alkaline solution at a temperature t, wherein t is in the range of: t = -4.82(c*d) + 92.3 °C ± 12.5 °C, wherein c is the concentration of sodium hydroxide (expressed in %), or equivalently pH, and d is the duration of the treatment (in hours).

5. The method according to claim 4, wherein step (a) comprises soaking the stems in the alkaline solution at a temperature t, wherein t is in the range of: t = -4.82(c*t) + 92.3 °C ± 6°C.

6. A method according to any one of claims 2 to 5, wherein step (w) comprises soaking the stems in water at a temperature of 95°C to 100°C, at normal atmospheric pressure, or in a pressurized container at a temperature of 100°C to 120°C and a pressure of 0-1 bar, for a period of 1 to 3 hours.

7. A method according to any one of claims 2 to 5, wherein step (w) comprises soaking the stems in a pool of water at an ambient temperature of 20°C to 45°C, in direct sunlight or in the shade, for a period of 1 to 16 weeks.

8. A method according to any preceding claim, comprising an initial step (c) of separating the leaflets from the palm fronds.

9. A method according to any preceding claim, comprising the prior step (d) of stripping the palm stem of its outer layer.

10. A method according to any preceding claim, comprising the prior step (e) of slicing the stem longitudinally to reduce its thickness.

11. A method according to any preceding claim, comprising a subsequent step (f) of washing and / or neutralising the product obtained in step (b).

12. A process according to any preceding claim, comprising the subsequent step (g) of drying the product obtained from step (f).

13. A method according to any preceding claim, comprising the step (h) of brushing the fibres / product obtained from step (g).

14. A process as claimed in claim 13, comprising the step (i) of degumming the fibres / product obtained from step (g) by treating the fibres at between 65°C and 110°C, with a low concentration of sodium hydroxide of 1% to 3%, a low concentration of hydrogen peroxide of 0.1% to 0.3%, and 0.3% to 0.9% sodium silicate.

15. The method according to claim 14, wherein step (i) further comprises treating the fiber with 0.3% to 0.9% ethylenediaminetetraacetic acid (EDTA), preferably for a period of 2 hours to 4 hours.

16. A method according to any preceding claim, comprising the step (i) degumming the fibres / product obtained from step (g) by treating the extracted fibres at between 50°C and 65°C, simultaneously with laccase having an activity of 2000 U / g and acid xylanase having an activity of 100,000 U / g, in a buffer solution at pH 4.8 for a period of between 6 hours and 10 hours.

17. A method of obtaining fiber from palm tree species, the method comprising the step of soaking the fiber stems in a pool of water having an ambient temperature of 20°C to 45°C.

18. The method of claim 17, wherein the soaking is carried out in direct sunlight or in the shade.

19. The method according to claim 17 or 18, wherein the soaking duration is 1 to 16 weeks.

20. A method of obtaining fiber from palm tree species, the method comprising the steps of: The midrib / inflorescence axis sections were placed in hot water at 80 °C to 100 °C at normal atmospheric pressure for 3 to 8 h.

21. The method according to claim 20, wherein the midrib / axis slices are placed in a pressurized container at a temperature of 100°C to 120°C and a pressure of 0 - 1 bar for a period of 1 to 3 hours.

22. The method of claim 20 or 21, wherein the midrib / axis sections are peeled prior to sectioning.

23. A fibre product derived using the method according to any preceding claim.

24. Cellulosic fluff derived from the fiber product according to claim 23.

25. An absorbent material for use in baby diapers and feminine hygiene pads, and for use in the manufacture of paper pulp.

26. A baby diaper comprising the absorbent material according to claim 26.

27. A feminine hygiene pad comprising the absorbent material according to claim 26.

28. An article of clothing or footwear comprising the fiber product according to claim 23.

29. A sheet of flexible material comprising the fibrous product according to claim 23.

30. An article for automobile or construction, such as a board or an insulating board, comprising the fiber product according to claim 23.

31. A rope comprising the fiber product according to claim 23.

32. Use of sodium lignin derived according to the method according to any one of claims 1 to 19.

33. A cement and concrete plasticizer, filler or adhesive comprising the sodium ligninate according to claim 32.

34. A felt comprising a mixture of gypsum and the fiber product according to claim 23.

Images