GB2637324A - Methods for the manufacturing of composite boards from textile and wood fibers - Google Patents

Abstract

A method of manufacturing fibreboard, the method comprising blending fiberised textile waste and wood fibres with a thermosoftening polymer resin using a rotary mixer to form a homogeneous mixture; and forming said mixture into a board or three-dimensional structure by pressing and applying heat. The textile waste may be shredded using a multi-stage shredding process. The fiberised textile waste and wood fibres may be mixed together in a dry state using a secondary mixing device, specifically a fan or a recirculating airline, which feeds the rotary mixer. The thermosoftening polymer resin may be selected from polyester, polyethylene or propylene powders or fibres, biocomponent fibres of polyethylene and polypropylene or adhesion promoters. The water content of the mixture may be controlled prior to pressing. Homogeneous resin distribution may be enabled via the addition of a wettability or adhesion promoter to the fibres. The mixture may be first compressed to approximately 0.1 g/cm3 and finally compressed to approximately 0.8 g/cm3 with the application of heat at around 150-180°C. Secondary pressing may be used to form a three-dimensional shape, including embossed features on the board surface. Fibreboard and composite materials formed by the method are also disclosed.

Description

METHODS FOR THE MANUFACTURING OF COMPOSITE BOARDS FROM

TEXTILE AND WOOD FIBERS

FIELD

The present invention relates to methods for the manufacturing of composite boards from textile and wood fibers. Composite boards manufactured according to methods of the present invention may be used for many applications including in connection with furniture and construction.

BACKGROUND

The fashion and textile industry is a significant contributor to pre-and post-consumer waste, generating over 50 million tons of waste in 2022, most of which ends up in landfills or is incinerated. Recycling textiles is difficult due to the heterogeneous nature of textile products, which include zippers, buttons, and labels, and are usually composed of blended fabrics such as polyester and cotton. Furthermore, waste textiles can be obtained from a diverse range of sources, including post-consumer waste (such as clothing and footwear), pre-consumer waste (such as cutting waste from garment manufacturing), construction waste, geotextiles, agricultural membranes, and landfill waste. Textile fibers consist primarily of polyester, cotton, man-made cellulose, nylon, and wool, each of which possess unique mechanical properties and surface chemistry. In addition, most textile fibers have been treated with dyes or pigments and coated with functional chemistry, such as waterproofing agents.

The current textile-to-textile recycling rate is less than 1%, primarily due to the challenges associated with collecting, sorting, disassembly, and chemically degrading textile products into raw materials. While there are ongoing efforts to develop textileto-textile recycling processes, these processes are likely to remain a small-scale niche due to the energy-intensive and greenhouse gas (GHG) emitting nature of the processes. Moreover, using virgin materials such as petrochemical-derived polyester or cultivated cotton may result in fewer GHG emissions compared to textile-to-textile recycling. Therefore, there is a pressing need to explore alternative strategies to recycle end-of-life textiles to avoid landfill and incineration, which contribute to environmental pollution. The current state of textile waste management necessitates the development of new technologies that can address the challenges of textile waste, promote sustainability, and reduce GHG emissions.

To address the challenges of textile waste, there is a need to find alternative strategies to recycle end-of-life textiles to avoid landfill and incineration. One promising solution is to use textile waste as a raw material for structural board, as textile products inherently embody mechanical strength. However, to date, attempts to use textile waste to form construction boards have been limited due to the absence of a large-scale continuous production method that meets standardized specifications.

Although the use of textile fiber waste for board production has been limited so far due to the lack of a large-scale continuous production method capable of producing standardized boards (ISO 16895:2016) and the inability to utilize unprocessed textile waste, the construction and furniture industries heavily rely on consistent, large-scale board materials that meet standard technical performance specifications. As such, it is crucial to enable the large-scale recycling of textile waste into boards that meet these specifications, delivering a sustainable solution to the problem of textile waste management. Notably, there have been some attempts to use textile waste for MDF board production, but these methods have thus far been unable to meet the required standards of the construction and furniture industries and are only at laboratory scale.

Medium density fiber (MDF) board is a widely used construction material manufactured from wood that has been shredded and milled into a fibrous fluff, typically featuring dimensions ranging from 10 to 100 millimeters by 10 to 100 microns. Wood chips and sawdust are collected from various sources, including sawmills and furniture factories. These materials are sorted and cleaned to remove any contaminants, such as metal or plastic. The wood fibers are created by grinding the wood chips and sawdust into small particles using a defibrator machine. The resulting fibers are screened to remove any oversized or undersized particles. The wood fibers are then mixed with wax and resin binder in a blending process or more commonly, these chemistries are applied in a blowline. The exact composition of the binder and the amount of wax used depend on the desired properties of the final product. The blended mixture is formed into a mat by spreading the fibers out evenly on a conveyor belt. The mat is then pre-compressed to remove any excess air and improve the overall density of the board. The pre-compressed mat is then placed in a hot press, where it is subjected to high pressure and temperature. This causes the resin binder to melt and bond the wood fibers together. After the hot press, the MDF board is cooled and trimmed to the desired size and shape. It is then sanded to a smooth finish, and any excess dust or debris is removed.

Depending on the final application, the MDF board may be laminated with a decorative veneer or coated with a layer of paint or primer. Industrial plants that produce MDF boards are capable of outputting between 200,000 and 500,000 tonnes of board each year, making MDF boards a popular and valuable construction material due to their durability and versatility. An example process of manufacturing MDF boards is shown in Fig. 1.

Improvements are desired to overcome shortcomings of existing implementations.

SUMMARY

In general terms, the present disclosure is directed to a method for manufacturing fiberboard by blending fiberized textile waste and wood fibers with a thermosoftening polymer resin, and then forming the mixture into a board or three-dimensional structure by pressing and applying heat. Advantageously, this invention addresses the problem of textile waste by providing a scalable method to convert it into valuable composite materials, which can be used in various industries such as construction, furniture, and transportation, thereby promoting sustainable waste management and upcycling.

In addition, the use of polyester thermosoftening resin binder in place of traditional urea-formaldehyde (UF) resin or diisocyanate binders confers two advantages. In comparison to UF resin there is no formaldehyde released after curing, which is considered potentially harmful to human health. Secondly, the use of polyester as the thermosoftening binder and most preferably in combination with textiles containing polyester enables a further recycling process to be performed. This recycling process entails the mechanical comminution of the board material to form a chipped or particulate form. The chemical degradation of the polyester via depolymerisation processes including: hydrolysis, glycolysis, thermomechanical dissolution, enzymatic digestion and other polyester chemical recycling techniques known in the art. The subsequent separation of the monomers derived from polyester used in the binder and the textile waste. The recycling of the monomers, carboxylic acids and di-alcohols, and the reuse of the separated cellulosic fraction, which includes the wood fibres and cellulosic textile fibres (cotton, linen, viscose, lyocell etc). The cellulosic fibres are most preferably used as a feedstock for the formation of boards and composite products via the same process. It is further envisaged that the monomers can be recycled chemically to be polymerised to form polyester and/or biochemically metabolised via a biological process to form a useful material.

This additional recycling step for polyester and cellulosic fractions enables a fully circular manufacturing loop to be implemented wherein the board and composite products will not need to be sent to landfill, incinerated or converted to oil via pyrolysis at end-of-life.

According to an aspect of the invention, there is provided a method of manufacturing fiberboard. The method comprises blending fiberised textile waste and wood fibers with a thermosoftening polymer resin using a rotary mixer to form a homogeneous mixture. The method also comprises forming said mixture into a board or three-dimensional structure by pressing and applying heat.

Optionally, the textile waste is shredded using a multi-stage shredding process.

Optionally, the textile waste is shredded to short fibres < 5 mm long by hammer milling.

Optionally, the fiberised textile waste and wood fibers are mixed together in a dry state using a secondary mixing device.

Optionally, the secondary mixing device is a fan or a recirculating airline. Optionally, one or more properties of the homogenous mixture can be controlled by varying the parameters of the rotary mixer and/or secondary mixing device.

Optionally, the thermosoftening polymer resin is selected from the group consisting of polyester resin, polyethylene, polypropylene, polyethylene powders or fibers, polypropylene powders or fibers, polyester powders or fibers, bicomponent fibers of polyethylene and polypropylene, and adhesion promoters.

Optionally, the method further comprises controlling the water content of the homogenous mixture before pressing.

Optionally, the method further comprises the addition of an adhesion promoter or wettability promoter to the fibers to enable homogeneous resin distribution.

Optionally, the homogeneous mixture is transferred to a board pressing system where it is first compressed to approximately 0.1 g/cm^3 and then compressed to a final density of approximately 0.8 g/cm^3 with the application of heat at around 150 to 180c.

Optionally, the pressed board undergoes a secondary pressing step to form the board into a three-dimensional shape.

Optionally, the three-dimensional shape includes embossed features on the surface of a board. According to an aspect of the invention, there is provided a fiberboard manufactured by a method described above.

Optionally, the fiberised textile waste constitutes between 5 to 50% of the dry weight of the mixture. According to an aspect of the invention, there is provided a composite material formed by the method described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures provided in this specification serve to further illustrate and explain the various aspects and embodiments of the present invention. In particular, the following figures depict several embodiments of the disclosed method. It is understood that the specific configurations and details shown in the figures are not intended to be limiting, and that other variations and modifications of the invention are possible.

Figure 1 is a flow chart of a prior art method of manufacturing MDF boards.

Figure 2 shows a rotary mixer configured to blend wood and textile fibers with resin.

Figure 3 shows wood and textile fibers mixed with resin.

Figure 4 shows a fiber board formed from a homogenous mix of textile and wood fibers mixed with resin.

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as "lower," "upper," "horizontal," "vertical," "above," "below," "up," "down," "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such. Terms such as "attached," "affixed," "connected," "coupled," "interconnected," and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the invention are illustrated by reference to the exemplified embodiments. Accordingly, the invention expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features; the scope of the invention being defined by the claims appended hereto.

Figure 2 illustratively shows a rotary mixer configured to receive and mix wood and textile fibers with a resin material such as a thermosoftening polymer resin. The rotary mixer primarily comprises a mixing chamber, the enclosed space wherein substances are combined or blended, safeguarded by walls to prevent any leakage or spillage. Within this chamber is a rotary shaft, a centralized and typically cylindrical component extending longitudinally, serving as the main axis of rotation. Affixed to the rotary shaft are mixing elements, which can be blade-like or helical structures, orchestrated to agitate, disperse, or amalgamate substances within the chamber as the shaft rotates. Propulsion for rotation is provided by a drive mechanism, typically involving a motor, which can be electric, hydraulic, or pneumatic, and is responsible for generating the necessary kinetic energy to rotate the shaft and subsequently, the mixing elements. In certain configurations, a gearbox may be incorporated to modify the motor's rotational speed, either amplifying or reducing it, to meet the specified mixing requirements. The combination of these components enables the efficient mixing or blending of various substances, whether they be fluids, powders, or granules, achieving a homogeneous mixture or specific dispersion pattern as needed.

Figure 3 illustratively shows a mix of wood and textile fibers which may, or may not, be blended with a resin. When wood and textile fibers are mixed within a rotary mixer along with a resin, the outcome is a composite mixture wherein fibers are impregnated and bonded by the resin, resulting in a material with enhanced characteristics. The Rotary Mixer effectively disperses the textile and wood fibers uniformly throughout the resin, ensuring each fiber is adequately coated and bonded.

The textile and wood fibers provide a reinforced structural matrix within the resin, lending their inherent strengths and properties to the resultant composite. This blend of materials, when cured, produces a robust and durable composite, with properties that can be fine-tuned by adjusting the ratios of the constituent materials, the type, and properties of the fibers and the resin used.

This composite mixture can offer enhanced mechanical properties, such as improved tensile strength, stiffness, and impact resistance, over the base resin material. It may also exhibit altered thermal and acoustic properties, depending on the specific types and proportions of wood, textile fibers, and resin combined.

Figure 4 illustratively shows a fiberboard manufactured using methods according to the disclosure. A fiberboard fabricated from the composite mixture, as previously outlined, exemplifies an advanced, structured material with superior properties gleaned from the integration of wood and textile fibers within a resin matrix. As will be described further below, once the mixing is complete, the composite mixture is heated and pressed. This process solidifies the resin, effectively locking the fibers in place and creating a rigid, stable structure.

The method according to the disclosure includes two basic steps: blending fiberised textile waste and wood fibers with a thermosoftening polymer resin using a rotary mixer to form a homogeneous mixture, and forming said mixture into a board or three-dimensional structure by pressing and applying heat.

The method of manufacturing fiberboard as disclosed in the invention utilizes a combination of fiberised textile waste and wood fibers, which are blended with a thermosoftening polymer resin. This process is designed to upcycle textile waste, a significant environmental concern due to the large volume of textile waste produced annually, estimated to be millions of tonnes globally. The fiberised textile waste is obtained from a variety of pre-and post-consumer fabrics, including but not limited to, cotton, polyester, nylon, and woolen materials. These materials can come from a wide range of sources such as discarded clothing, household textiles like curtains and bed linens, and even industrial textile waste.

The process is designed to be highly efficient and does not require item sorting or preparative processing. This means that textiles of different types and colors can be processed together, eliminating the need for labor-intensive sorting processes. The textiles are first shredded into small pieces using industrial shredding machines, then further fiberised into a fluffy, cotton-like material. This fiberization process is critical as it increases the surface area of the textile waste, allowing for better interaction with the wood fibers and thermosoftening polymer resin in the subsequent blending process.

The production process begins with the collection of post-consumer textile waste, comprised of diverse items such as garments, curtains, and bed wear, and it is anticipated to have a heterogeneous composition, including but not limited to polyester, cotton, nylon, assorted dyes, functional chemistries, and hard components such as buttons and zippers. This textile waste undergoes an initial phase of size reduction through cutting and shredding with the use of an industrial machine to yield smaller, manageable pieces.

Subsequently, these textile pieces are subjected to a meticulous multi-stage shredding process designed to remove all hard points like zippers and buttons and to fiberize the material by mechanically pulling apart the textiles to produce opened fiber materials. This process ensures the elimination of any components that could impede the subsequent mixing process. The degree of openness of the fibers can be precisely controlled to optimize compatibility and interaction with wood fibers and thermosoftening polymers in the downstream mixing process, ensuring uniformity and integrity in the resulting mixture.

The blending process is performed using a rotary mixer, a high-capacity industrial machine that ensures a homogeneous mixture of the textile waste, wood fibers, and thermosoftening polymer resin. The rotary mixer operates by rotating a large drum containing the materials, causing them to tumble and mix together. The speed and duration of the mixing process can be adjusted to ensure optimal blending of the materials. The wood fibers used in the process can come from a variety of sources, including hardwood and softwood species, and can be in the form of wood chips, sawdust, or other wood waste materials. The thermosoftening polymer resin acts as a binder, helping to hold the fibers together and giving the final product its strength and durability.

Once the blending process is complete, the mixture is then formed into a board or three-dimensional structure through a pressing and heating process. This involves feeding the mixture into a press, which applies pressure and heat to the material. The pressure can be adjusted to control the density of the final product, while the heat causes the thermosoftening polymer resin to melt and flow around the fibers, binding them together. Once the resin cools and hardens, the board or three-dimensional structure is removed from the press and allowed to cool further.

In some embodiments the fiberised textile waste and wood fibers are mixed together in a dry state using a secondary mixing device.

Advantageously, the dry blending of the fiberised textile waste and wood fibers ensures a homogeneous mixture, which is critical for the mechanical robustness of the resulting composite material. The secondary mixing device can be a fan or a recirculating airline, which further enhances the mixing process. The dry blending process is scalable and can be applied both at a small scale, for local manufacturing of construction boards, and at an industrial scale, for processing thousands of tonnes of waste per year. This process is particularly beneficial for local textile recycling sites and resource-poor settings, where large-scale industrial plants may not be feasible.

In some embodiments, the process involves blending fiberised textile waste and wood fibers with a thermosoftening polymer resin, and then forming the mixture into a board or three-dimensional structure by pressing and applying heat.

Advantageously, the process provides a comprehensive method for manufacturing fiberboard using a combination of wood-based and textile-based fibers with thermosoftening polymers. The textile fibers are obtained from pre-and post-consumer fabrics, which are processed without the need for item sorting or preparative processing. The blending process involves the use of a rotary drum mixer, which ensures a homogeneous mixture of the textile waste, wood fibers, and thermosoftening polymer resin. The thermosoftening polymers used in the composition of the composite include aqueous suspensions of polyester resin, polyethylene or polypropylene, polyethylene powder or fibers, polypropylene powder or fibers, polyester powder, or fibers, and bicomponent fibers of polyethylene and polypropylene. These polymers are convenient to handle and do not pose the same occupational safety risks as reactive binder chemistries used in fiberboard manufacturing. The mixture is then formed into a board or three-dimensional structure through a pressing and heating process, which can be performed at 150-200C. This process allows the fibers to be consolidated and the thermosoftening polymer to be melted or softened to allow flow and bonding as it cools and solidifies. The resulting composite material can be used in various applications, including construction, furniture, and transportation.

In some embodiments the fiberised textile waste constitutes between 5 to 50% of the dry weight of the mixture.

Advantageously, the inclusion of fiberised textile waste in the range of 5 to 50% of the dry weight of the mixture allows for the efficient utilization of textile waste, which is a significant environmental concern. The textile waste is obtained from post-consumer textile waste, such as garments, curtains, and bed wear, which are then cut and shredded using an industrial machine. The textile pieces are further fiberised using a multi-stage shredding process that removes all hard points, such as zippers and buttons, and produces opened fiber materials by mechanically pulling the textile apart. The degree of openness of the fiber can be controlled to optimize the downstream mixing process. This process is critical in ensuring that the textile waste is adequately prepared for blending with the wood fibers and thermosoftening polymer resin.

It will be understood that the term bicomponent fibers as used herein may refer to fibers composed of two different polymers, typically arranged in a core-sheath or sideby-side configuration, which are often used in the textile industry for their unique properties such as self-crimping, bonding ability, and differential shrinkage. It will be understood that the term adhesion promoters as used herein may refer to substances or materials that enhance the bonding properties of the thermosoftening polymer resin to the fiberised textile waste and wood fibers in the process of manufacturing fiberboard.

It will be understood that the term wettability promoter as used herein may refer to a substance or material, such as a surfactant, that enhances the ability of a liquid (like the thermosoftening polymer resin) to spread across or penetrate into the fiberised textile waste and wood fibers, thereby improving the adhesion and cohesion within the formed fiberboard.

What has been described and illustrated herein is an example along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the spirit and scope of the subject matter, which is intended to be defined by the following claims --and their equivalents --in which all terms are meant in their broadest reasonable sense unless otherwise indicated.

Claims (19)

1. CLAIMS1. A method of manufacturing fiberboard, the method comprising: a. blending fiberised textile waste and wood fibers with a thermosoftening polymer resin using a rotary mixer to form a homogeneous mixture; and b. forming said mixture into a board or three-dimensional structure by pressing and applying heat.
2. 2. The method of claim 1, wherein the textile waste is shredded using a multi-stage shredding process.
3. 3. The method of claim 1, wherein the fiberised textile waste and wood fibers are mixed together in a dry state using a secondary mixing device.
4. 4. The method of claim 3, wherein the secondary mixing device is a fan or a recirculating airline.
5. 5. The method of claim 4, wherein the secondary mixing device feeds the rotary mixer.
6. 6. The method of claim 4 or claim 5, wherein one or more properties of the homogenous mixture can be controlled by varying the parameters of the rotary mixer and/or secondary mixing device.
7. 7. The method of claim 1, wherein the thermosoftening polymer resin is selected from the group consisting of polyester resin, polyethylene, and polypropylene, polyethylene powders or fibers, polypropylene powders or fibers, polyester powders or fibers, bicomponent fibers of polyethylene and polypropylene, adhesion promoters.
8. 8. The method of claim 1, further comprising controlling the water content of the homogenous mixture before pressing.
9. 9. The method of claim 1, further comprising the addition of an adhesion promoter or wettability promoter to the fibers to enable homogeneous resin distribution.
10. 10. The method of claim 1, wherein the homogeneous mixture is transferred to a board pressing system wherein it is first compressed to approximately 0.1 g/cm^3 and then compressed to a final density of approximately 0.8 g/cm^3 with the application of heat at around 150 to 180C.
11. 11. The method of claim 1, wherein the pressed board undergoes a secondary pressing step to form the board into a three-dimensional shape.
12. 12. The method of claim 11, wherein the three-dimensional shape includes embossed features on the surface of a board.
13. 13.A fiberboard manufactured by the method of claims 1 to 12.
14. 14. The fiberboard of claim 13, wherein the fiberised textile waste constitutes between 5 to 50% of the dry weight of the mixture.
15. 15.A composite material formed by the method of claims 1 to 12.
16. 16. The method of any of claims 1 to 12 wherein the composite material or fibreboard is recycled using a process that depolymersies the polyester resin binder and polyester textile fibres.
17. 17.The method of claim 16 wherein the cellulosic fraction extracted from the composite material or fibreboard and reused as a raw material input for a subsequent process.
18. 18. The method of claim 16 wherein the depolymerised polyester is used as a raw material input for polyester production.
19. 19. The method of claim 16 wherein the depolymerised polyester is used as a raw material input for a further chemical, biochemical or biological transformation to form a useful material.