Method for melt-processing textile waste materials and product obtained by this method

Abstract

The present disclosure relates to a method for melt processing textile waste materials, the textile waste materials comprising: (1) at least one thermoplastic polymer material such as polyurethane, polyester, nylon, cellulose, or elastane; and (2) at least one cellulose-containing material such as cotton textiles, cotton blends with synthetic or natural polymers, regenerated cellulose-based textiles; the method being adapted to prepare a composite material and comprising: (a) chemically pretreating the textile waste materials; and (b) thermomechanically processing the chemically pretreated materials of step (a), including melt compounding and optionally adding recycled PET; plasticizers such as glycerol, PEG, and vegetable oils; and / or toughening polymers such as natural rubber and polyurethane, whereby a composite material comprising a homogeneous polymer composite and / or nanocomposite is obtained, the at least one thermoplastic polymer material essentially constituting a matrix phase and the at least one cellulose-containing material essentially constituting a reinforcing phase of the composite material. The present disclosure further relates to a composite material obtained by the method, a recycled product obtained by the method, a 3D printable filament obtained by the method, and a 3D printed recycled product obtained by the method. TIFF2025522854000003.tif85128

Description

Technical Field

[0001] The present disclosure relates to a method for melt-processing textile waste materials, a composite material obtained by the method, a recycled product obtained by the method, a 3D printable filament obtained by the method, and a 3D printed recycled product obtained by the method, as defined in the introductory part of the independent claims.

Background Art

[0002] For environmental purposes, there is an increasing demand for means and methods for recycling waste materials. This has become relevant also for textile waste materials in order to produce new products from waste materials in an efficient and environmentally friendly way. Today, several methods are used for recycling and / or separating the various components of textile waste materials. However, current methods have limitations and drawbacks, for example, with respect to the usefulness for textile waste materials that contain both, for example, a thermoplastic polymer and a fabric of cotton and / or cellulose.

[0003] CN-A-113005536 (Patent Document 1) discloses nanoscale plastic particles and a method for preparing them, which involves dissolving plastic powder in an organic solvent. US-A-2019136455 (Patent Document 2) discloses a cellulose material and a method for making the cellulose material in the context of cotton recycling, where the method involves dissolving or suspending an active ingredient in a medium containing the cellulose material by contacting a cotton fabric with an oxidation system to obtain an oxidized cotton material. US-A-20210269969 (Patent Document 3) discloses a process for separating a cellulose portion from a raw material composition containing polyester and cellulose, which involves using a hydrolyzing liquor to alkalize a polyester / cellulose blend. WO 2021 / 181007 (Patent Document 4) discloses a method for separating cellulose-based fibers and non-cellulose-based fibers from a textile material of mixed fibers, including mechanical disintegration of the textile material, followed by acid treatment and then alkali treatment. IN-A-202011022177 (Patent Document 5) discloses the production of nanofibers from waste plastic bottles.

[0004] As shown in the literature, the majority of textile sorting processes to date have focused on cotton or polycotton (Palme et al Text. Cloth. Sustain 2017, 3 (4)(Non-Patent Document 1)) and follow the following chemical recycling routes: (i) dissolution and wet spinning (Liu et al., Carbohydrate Polymers 206 (2019) 141-148)(Non-Patent Document 2); (ii) extraction of cellulose nanocrystals (Wang et al Carbohydrate polymers 2017, 157, 945-952(Non-Patent Document 3); Zhong et al Carbohydrate Polymers 240 (2020) 116283(Non-Patent Document 4)); (iii) chemical dissolution of polyester and recovery of cellulose (S. Yousef et al. Journal of Cleaner Production 254 (2020) 12007(Non-Patent Document 5)). Therefore, the efforts in Sweden by Renewcell to recycle cotton or polycotton to produce new textile fibers, where a chemical process breaks down the textile into monomers or polymers and then spins them into fibers, have attracted great interest( https: / / www.renewcell.com / en / section / our-technology / ). At the same time, a green fractionation of textile blends into nanoscale cellulose and polymers has been developed by Mathew et al (Ruiz Caldas et al, ACS Sust Chem Eng. 2022, 10: 3787(Non-Patent Document 6)); they have been producing CNCs from undyed and dyed cotton, as well as its blends with polyester and acrylic in recent years. It has also been noted that colored nanocellulose can be obtained through this process.

[0005] One problem associated with prior art solutions is that complete separation or depolymerization of components is typically required for recycling purposes, which requires affordable costs, high energy demands, and complex manufacturing processes. Therefore, there is a need for improved, more environmentally friendly, and simplified methods for recycling textiles.

[0006] Carette et al, (J Polym Environ 2021; 29: 662 - 671) (Non - Patent Document 7) reported using PET from bottles and cellulose from textiles in the preparation of composites. Their components are from different sources and the PET is not of textile origin. Wang et al, (J Appl Polym Sci 2013; 128: 3555 - 3563) (Non - Patent Document 8) used waste cotton fabric in combination with thermoplastic PU derived from non - textile sources. Their process does not include a chemical treatment step. WO 2022 / 112719 A1 (Patent Document 6) uses fibers from textiles in combination with polymers from non - textile sources. In these studies, the fiber size remains within the same range (micron scale) as the supplied textile.

[0007] The approach of the present disclosure enables the use of polymers and cellulose fibers from the same fabric. Further, the chemical pretreatment step followed by a thermomechanical process enables the reduction of the fibers from a typical diameter of cotton fibers (about 100 microns) down to 100 nm (even to the nanoscale).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

[0009] [Non-Patent Document 1] Palme et al Text. Cloth. Sustain 2017, 3 (4) [Non-Patent Document 2] Liu et al., Carbohydrate Polymers 206 (2019) 141-148) [Non-Patent Document 3] Wang et al Carbohydrate polymers 2017, 157, 945-952 [Non-Patent Document 4] Zhong et al Carbohydrate Polymers 240 (2020) 116283 [Non-Patent Document 5] S. Yousef et al. Journal of Cleaner Production 254 (2020) 12007 [Non-Patent Document 6] Ruiz Caldas et al, ACS Sust Chem Eng. 2022, 10: 3787 [Non-Patent Document 7] Carette et al,(J Polym Environ 2021; 29: 662-671) [Non-Patent Document 8] Wang et al,(J Appl Polym Sci 2013; 128: 3555-3563) [Summary of the Invention]

[0010] Overview Thus, since prior art methods typically use complete chemical separation or depolymerization of components to recycle, the inventors have found promise in the opportunity to fractionate the textile partially into a suitable hybrid before converting it into a new product.

[0011] One object of the present disclosure is to mitigate, alleviate, or eliminate one or more of the above-mentioned drawbacks and disadvantages in the prior art and to solve at least the above-mentioned problems.

[0012] In a first aspect, a method for melt processing textile waste materials is provided, the textile waste materials comprising (1) at least one thermoplastic polymer material such as polyurethane, polyester, nylon, or elastane, and (2) at least one cellulose-containing material such as cotton textiles, cotton blends of synthetic or natural polymers, regenerated cellulose-based textiles, the method being adapted to prepare a composite material, (a) chemically pretreating the textile waste materials; and (b) thermomechanically processing the chemically pretreated materials of step (a), including melt compounding, optionally adding recycled PET; plasticizers such as glycerol, PEG, and vegetable oils; and / or toughening polymers such as natural rubber and polyurethane, comprising thereby obtaining a composite material comprising a well-dispersed polymer composite and / or nanocomposite, wherein the at least one thermoplastic polymer material essentially constitutes a matrix phase and the at least one cellulose-containing material essentially constitutes a reinforcing phase of the composite material.

[0013] Thereby, a protocol for melt processing a textile to prepare a composite in which a thermoplastic polymer acts as a matrix and cotton fibers act as a reinforcing phase is developed as a commercially viable processing route for recycling textiles. Typically, the thermoplastic polymer material and the cellulose-containing material are derived from the same textile waste material, i.e., the same textile source, which is advantageous by simplifying the recycling process. To facilitate the melt compounding process (i.e., melt processing) and to optimize the production of well-dispersed polymer composites and nanocomposites in a one-step process without separating them into their components, a pretreatment using a chemical process route is employed. This can be controlled by keeping the weight loss between the supply fabric and the composite below 5 wt%. Melt processing typically does not chemically modify the material, but the material is physically modified (by reducing the size of the cellulose fibers) to become a homogeneous composite or nanocomposite. However, chemical modification can also be performed if additional chemicals are added to create grafts on the cellulose or polymer phase. Furthermore, the process is environmentally friendly and provides a way for sustainable recycling of textile waste. For example, advantages exist in that there is no secondary pollution resulting from the recycling process and in that all fibrous components of the consumed textile are used by being converted into new products, i.e., composite materials and subsequent 3D printable filaments. This process can be extended to other cotton blends containing nylon, elastane, etc.

[0014] In some embodiments, the chemical pretreatment is selected from at least one of the following routes: (i) Partial dissolution of at least one thermoplastic polymer material using TFA (trifluoroacetic acid) and DCM (dichloromethane) in a ratio of 1:1 to 1:2; (ii) Citric acid hydrolysis of any cellulose occurring in at least one thermoplastic polymer material and / or at least one cellulose-containing material; and (iii) Any TEMPO-mediated oxidation of cellulose occurring in at least one thermoplastic polymer material and / or at least one cellulose-containing material.

[0015] This provides an alternative route for chemical pretreatment, i.e., by reducing the size and phase of one of the components in the textile while keeping the other components intact, it is possible to fractionate the textile material only partially. There are three independent process routes with different advantages. The "thermoplastic polymer material" may also be referred to as the "thermoplastic polymer PET phase". Procedure (i) is most advantageous for cotton blends, and procedures (ii) and (iii) are advantageous for both pure cotton and cotton blends. The chemical pretreatment of the present disclosure results in some changes in surface chemistry, such as oxidation, but the melt processing itself only leads to homogenization of the mixture and reduction in the size of the cellulose phase. In the case of procedures (ii) (citric acid route) and (iii) (TEMPO route), the melt processing step may lead to nano-scaled cellulose in the product. In this context, "nano-scaled" refers to any cellulose (or other material) having a size smaller than 100 nm. Therefore, for particles to be called "nano-sized" or "nano-scaled", they must be smaller than 100 nm in at least one dimension.

[0016] Route (i) is an organic solvent-based process, and routes (ii) and (iii) are water-based processes. In route (i), the polymer phase is partially dissolved (by controlling the amount and ratio of the solvent used), and the cellulose phase remains unchanged. In routes (ii) and (iii), the cellulose fraction is modified and / or hydrolyzed, and the polymer phase remains unchanged.

[0017] Chemical treatment removes amorphous cellulose and / or adds chemical groups to cellulose (sulfate groups, citrate groups, carboxyl groups) and / or makes the cellulose fiber structure less compact (by reducing interactions, oxidation or esterification). Physically, the change is related to weakening the cellulose fiber structure by cutting across or along the fiber length to produce fibers / fibrils with a diameter shorter than the feed (50 μm to 100 nm).

[0018] Thus, chemical pretreatment routes (ii) and (iii) (such as those shown in Example 8) have been successful in functionalizing cellulose in textiles and textile blends with chemical groups for ionic crosslinking or for interacting with waterborne contaminants. Chemical groups on the cellulose phase promote the occurrence of nanofibrillation during thermomechanical processing.

[0019] In some embodiments, after chemical pretreatment by route (ii) and / or (iii), fibrillation using a mechanical process and bead processing using (j) a thermally induced phase separation method or (jj) an oven drying method (as exemplified in Example 4) are carried out prior to subsequent thermomechanical processing. The fibrillation step has the effect of converting cotton into nanoscale cellulose, and bead preparation is a process for developing pellets for subsequent thermomechanical processing.

[0020] In some embodiments, textile waste materials are melt processed at a temperature below 250°C at ambient pressure.

[0021] Thereby, a thermoplastic polymer suitable for the process of the present disclosure is used.

[0022] In some embodiments, the cellulose-containing material comprises polymorphs of cellulose I and / or cellulose II.

[0023] Thereby, a suitable cellulose-containing material is used.

[0024] In some embodiments, the textile waste material is selected from textile clothing or shoes to be recycled; polyester blends; cotton blends containing polyester, elastane, cellulose, polyurethane, and / or nylon; shredded polycotton; and shredded acrylic cotton.

[0025] Thereby, a suitable source of the material is used as the starting material. Other sources of textile materials may also be used as long as the other requirements presented in this disclosure are met.

[0026] In some embodiments, the method includes using the composite material obtained in step (b) for processing by injection molding, compression molding, or any other melt processing method, thereby obtaining a recycled product.

[0027] Thereby, the obtained composite material is processed and used for 3D printing without subsequent preparation.

[0028] In some embodiments, the method further includes filament processing the composite material obtained in step (b), including filament extrusion to produce a 3D printable filament.

[0029] Thereby, the composite material is prepared for subsequent 3D printing.

[0030] In some embodiments, the method includes using the 3D printable filament obtained for 3D printing, thereby obtaining a 3D printed recycled product.

[0031] Thereby, a 3D printed final product is obtained.

[0032] In a second aspect, a composite material is provided that includes a well-dispersed polymer composite and / or nanocomposite, where (1) at least one thermoplastic polymer material essentially constitutes a matrix phase and (2) at least one cellulose-containing material essentially constitutes a reinforcing phase of the composite material; the at least one thermoplastic polymer and the at least one cellulose-containing material originate from the same textile waste material.

[0033] Thereby, a novel composite material is provided by a novel process, thereby providing advantages in terms of process efficiency, cost, environmental aspects, and material properties. Composite materials with high cellulose content can also be obtained. The cellulose content can be up to 50%, up to 60%, or up to 75% for microcomposites and up to 20% for nanocomposites. And also, by using the composite material as a masterbatch, if necessary, the composite mixture can be diluted with other polymers, thereby reducing the amount of cellulose.

[0034] The synthetic fiber portion melts and loses its fiber structure and becomes the matrix phase, so the composite material undergoes a physical change. The cellulose fibers reduce in length and diameter during melt compounding. Typically, no chemical change is expected for either cotton fibers or synthetic fibers.

[0035] In some embodiments, the at least one thermoplastic polymer material originates from polyurethane, polyester, nylon, cellulose, or elastane, and the at least one cellulose-containing material originates from cotton textiles, cotton blends with synthetic or natural polymers, or regenerated cellulose-based textiles.

[0036] Thereby, suitable materials for obtaining the composite material are provided.

[0037] In some embodiments, the composite comprises (i) recycled PET; (ii) plasticizers such as glycerol, PEG, and vegetable oils; and / or (iii) toughening polymers such as natural rubber and polyurethane.

[0038] By including plasticizers in the melt compounding, homogenization during melt processing is promoted. Similarly, the product becomes more flexible. Additionally, the toughening agent helps prevent the formulation from becoming brittle and can also be used to adjust the toughness of the composite. Thus, by adding recycled PET, based on the masterbatch principle described above, i.e., using the composite composition as a masterbatch and mixing it with other polymers to adjust the composition, the composition of the composite can be adjusted. Recycled PET may be added from other sources and processing routes (see, e.g., Ruiz Caldas et al, ACS Sust Chem Eng. 2022, 10: 3787).

[0039] In some embodiments, the thermoplastic polymer is melt processable at a temperature below 250 °C at ambient pressure.

[0040] In some embodiments, the cellulose-containing material comprises polymorphs of cellulose I and / or cellulose II.

[0041] In some embodiments, compared to the original textile waste material, either (1) the thermoplastic polymer material is fractionated and the cellulose-containing polymer is intact, or (2) the thermoplastic polymer is intact and the cellulose-containing material is fractionated. As a result of the chemical pretreatment according to the present disclosure, a partially fractionated composite material is obtained, whereby the fractionated components exhibit a reduced size or phase.

[0042] In some embodiments, the composite material may contain nanoscale cellulose, which can be obtained, for example, by fractionating the cellulose-containing material based on route (ii) or (iii) according to the present disclosure. The nanoscale cellulose may be advantageous for subsequent products based on the composite materials of the present disclosure.

[0043] In some embodiments, the composite material is in the form of pellets.

[0044] Thereby, recycled composite pellets can be provided as products. The pellets obtained according to the present disclosure are typically in the form of beads with a diameter of 0.5 to 1 cm, containing up to 50 wt% cellulose.

[0045] In a third aspect, a recycled product is provided that includes the composite material of the second aspect and is further melt-processed by injection molding, compression molding, or any other melt-processing method.

[0046] Thereby, products are made by using these methods, changing the shape and form of the composite, whereby recycled products are obtained from the composite material without involving subsequent 3D printing steps. At this stage, neither physical changes nor chemical changes are expected.

[0047] In a fourth aspect, a 3D printable filament is provided that includes the composite material according to the second aspect of the present invention and is further filament-processed by filament extrusion for later use in 3D printing to obtain a 3D printed recycled product.

[0048] Thereby, a 3D printable filament based on the obtained composite material can be provided; the filament can be defined as a continuous filament with a defined diameter (typically 2.85 mm or 1.75 mm) that can be used in a 3D printer for in-fused filament deposition.

[0049] In a fifth aspect, there is provided a 3D printed recycled product that includes the 3D printable filament of the fourth aspect and is further 3D printed.

[0050] Thereby, a 3D printed recycled product is provided. 3D printing has the effect of giving structure to the product, but no physical or chemical changes are predicted. However, 3D printed products made from recycled textiles are unique.

[0051] In some embodiments, the 3D printed recycled product is selected from shoes, interior decoration products, accessories, or water filters.

[0052] In the case of water filters, the surface chemistry of cellulose has a beneficial effect and also enhances the relevance and uniqueness of the chemical treatment of the textile. Similarly, any other product type that can be 3D printed based on this composite material is also within the scope of the present disclosure.

[0053] The effects and features of the second to fifth aspects are quite similar to those described in relation to the first aspect. The aspects mentioned in relation to the first aspect generally also apply to the second to fifth aspects.

[0054] For example, the products and materials defined by the second to fifth aspects may also be obtained by the method of the first aspect.

[0055] The present disclosure will become apparent from the following detailed description. The detailed description and specific examples are only illustrative of the preferred embodiments of the present disclosure. It will be understood by those skilled in the art that changes and modifications can be made within the scope of the present disclosure from the guidance in the detailed description.

[0056] Accordingly, it should be understood that the disclosure herein is not limited to the specific compositions of the products described or the steps of the methods described; such products and methods can vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It should be noted that the articles “a,” “an,” “the,” and “said” as used in this specification and the appended claims are intended to mean that there is one or more of its elements unless the context clearly dictates otherwise. Thus, for example, references to “a unit” or “the unit” can include a plurality of devices, and so forth. Further, the terms “comprising,” “including,” “containing,” and like expressions do not exclude other elements or steps.

[0057] Definition The term “well dispersed” should be interpreted as meaning that the formulation / composite is homogeneous. The term also means that all components of the composite are evenly dispersed and distributed throughout the material. This property is important for the good and reliable performance of the material and does not exhibit sample-to-sample or batch-to-batch variations.

[0058] The term “matrix” should be interpreted as the continuous phase that acts as the binding phase of the composite material, while the term “reinforcements” is the dispersed phase and provides an increase in the mechanical properties to the matrix. Thus, the “matrix phase” is the continuous binding phase in the composite in which the fibers are dispersed, and the “reinforcing phase” is the fiber components in the composite, which typically have a higher stiffness than the matrix phase.

[0059] The term "PET phase" should be construed as the polyethylene terephthalate part of the textile.

[0060] The above objects, as well as further objects, features, and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of exemplary embodiments of the present disclosure, taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0061]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0062] Detailed description Next, the present disclosure will be described with reference to the accompanying drawings showing preferred exemplary embodiments of the present disclosure. However, the present disclosure may be embodied in other forms and should not be considered limited to the disclosed embodiments herein. The disclosed embodiments are provided to fully convey the scope of the present disclosure to those skilled in the art.

[0063] Figure 1 shows a scheme of a process according to the present disclosure for melt - processing textile waste materials, where textile waste materials such as recyclable textile clothing or shoes; polyester blends; cotton blends containing polyester, elastane, cellulose, polyurethane, and / or nylon; shredded polycotton; and shredded acrylic - cotton are used as starting materials. The textile waste materials include at least one thermoplastic polymer material such as polyurethane, polyester, nylon, cellulose, or elastane; and at least one cellulose - containing material such as cotton textiles, cotton blends with synthetic or natural polymers, or regenerated cellulose - based textiles. Typically, the thermoplastic polymer material is melt - processable at a temperature below 250 °C at ambient pressure, which is suitable for the processes and thermomechanical stages of the present disclosure. The cellulose - containing material is typically in the polymorphic form of cellulose I and / or cellulose II, which has been found to be advantageous.

[0064] In the first chemical pretreatment stage, the textile waste materials are only partially dissolved, i.e., complete disintegration is avoided. This can be achieved by any of the alternative routes of the present disclosure: (i) Partial dissolution of at least one thermoplastic polymer using TFA (trifluoroacetic acid) and DCM (dichloromethane) in a ratio of 1:1 to 1:2; (ii) Citric acid hydrolysis of cellulose in at least one thermoplastic polymer material and / or at least one cellulose - containing material, where the concentration of citric acid is typically about 80 - 85 wt% and the temperature is typically between 90 - 100 °C (under normal conditions); and (iii) TEMPO-mediated oxidation of cellulose in polycotton; here, the ratio of textile to reagent is an important parameter. The textile material at a concentration of 2 wt% in an aqueous medium was chemically treated at pH 10 maintained with 2 M NaOH solution using 0.1 mmol of TEMPO, 0.1 g of NaBr, and 10 mmol of NaClO per gram of cellulose. After 4 hours, the oxidized material was thoroughly washed until the conductivity was less than 10 μS / cm. The ratio may typically vary between 5 - 10 mol of NaClO per gram of cotton / cellulose, and the concentration of the textile in water may be in the range of 1 - 3 wt%.

[0065] Procedure (i) is most advantageous for cotton blends, and procedures (ii) and (iii) are advantageous for both pure cotton and cotton blends. Chemical pretreatment brings about some changes in surface chemistry, such as oxidation, for example, but the melt processing itself only leads to the homogenization of the mixture and the size reduction of the cellulose phase (as small as 50 nm). For example, oxidation typically changes the hydroxyl groups, and carbonyl or citrate groups in cellulose. This was confirmed by chemical analysis (FTIR and NMR). In the case of procedure (iii) (the TEMPO route), the melt processing stage leads to nanoscale cellulose in the product.

[0066] Following the chemical pretreatment based on route (ii) or (iii), an intermediate stage with fibrillation using a mechanical process and bead processing using a thermally induced phase separation method may be carried out. Thereby, intermediate products in the form of cellulose, polymer, and / or nanocellulose may be provided.

[0067] Alternatively, the textile (2 wt%) in the chemically treated aqueous dispersion was dispersed for 20 minutes using a High-Shear Dispermix (Ystral GmbH, Germany). The resulting dispersion was cast into a film with a thickness of 1 - 2 cm and dried overnight in an oven at 60°C. The dried film was cut into small square pellets (1 cm x 1 cm) using a commercially available paper cutter, followed by a thermomechanical process. This alternative step is carried out after the chemical process and is typically required to melt and blend the two phases into a homogeneous masterbatch or composite.

[0068] The chemical pretreatment may optionally be followed by fibrillation and / or beading, and subsequently a thermomechanical processing step including melt compounding may be carried out, where additional components may be added. These components include, for example, (i) recycled PET; (ii) plasticizers such as glycerol, PEG, and vegetable oils; and / or (iii) toughening polymers such as natural rubber and polyurethane; etc., to promote the homogeneity of the resulting composite material and finely tune the material properties (such as flexibility, brittleness, and toughness). These properties can be measured by microscopic observation data and mechanical property data.

[0069] As a result of the chemical pretreatment and thermomechanical processing, a composite material is obtained, which comprises a well-dispersed (homogeneous) polymer composite and / or nanocomposite, with at least one thermoplastic polymer material essentially constituting the matrix phase and at least one cellulose-containing material essentially constituting the reinforcing phase of the composite material.

[0070] Ideally, all components of the composite are evenly dispersed and distributed throughout the material, which can be measured using microscopic observations (such as optical microscopy, scanning electron microscopy, atomic force microscopy, etc.). This property is important for the good and reliable performance of the material and does not exhibit sample-to-sample or batch-to-batch variations. Furthermore, chemical pretreatment brings about some changes in surface chemistry, such as oxidation, but the melt processing itself leads to homogenization of the mixture and size reduction of the cellulose phase. In the case of procedures (ii) (citric acid route) and (iii) (TEMPO route), the melt processing step may lead to nanoscale cellulose in the product.

[0071] The composite material obtained after the thermomechanical process stage may preferably be directly used to obtain recycled products in the form of pellets, etc., after processing by injection molding, compression molding, or any other melt processing method. Therefore, this composite may be used to make products by other methods widely used in the polymer industry. This is further added to the point that 3D printing is possible.

[0072] Alternatively, the composite material obtained after thermomechanical processing is filament extruded to produce 3D printable filaments. The resulting filaments typically have a diameter of 1.75 or 2.85 mm (+ / - 0.05 mm) and are produced at a speed of 2 meters per minute.

[0073] The 3D printable filaments obtained after filament extrusion may be provided as such (i.e., as a marketable final product) and / or provided for subsequent processing, such as 3D printing.

[0074] Alternatively, the 3D printable filaments obtained after filament extrusion are used in a 3D printing process to obtain 3D printed recycled products such as shoes, clothing, apparel, interior decoration, accessories, or water filters. For example, the 3D printing may be performed at a temperature of 220 °C using an Ultimaker S5 (Ultimaker BV, Netherlands) printer. However, other printers and conditions may also be used.

[0075] Figure 2 discloses the stages of a thermo-mechanical process that is part of the process of the present disclosure; here, composite fibers are produced within a melt processing device, possibly by adding a reinforcing material and / or toughening agent, and the resulting extrudate is cooled in a water bath. The temperature profile during this process is typically 200 - 225 °C.

[0076] Next, the present invention will be further described with reference to examples of aspects and process steps.

Examples

[0077] Example 1 - Chemical pretreatment route (i) - Partial dissolution of the thermoplastic polymer Cotton / polyester blends with different PET contents are used as starting materials.

[0078] Partial dissolution A PET / cotton (60 / 40) fabric is cut into 2 cm x 2 cm squares. 100 g of the cut fabric is partially dissolved in a mixture of TFA (trifluoroacetic acid) + DCM (dichloromethane) with a ratio of 1:2 of TFA / DCM. The partially dissolved textile is dried overnight and further pulverized into a finer powder.

[0079] Example 2 - Chemical pretreatment, procedure (ii): Citric acid hydrolysis Cotton; and cotton blends with polyester, acrylic, or elastane are used as starting materials.

[0080] Esterification and partial hydrolysis of cotton Cotton textile fragments were cut into small pieces (<1 cm) and placed in a round-bottom flask containing anhydrous citric acid and water at a concentration of 85 wt%. The ratio of textile to pure citric acid was 1:20 (g / g). The flask was immersed in an oil bath and heated to 100 °C with mixing. The mixture was stirred at 300 rpm using an overhead mechanical stirrer until the citric acid was completely dissolved, and then quenched by 5-fold dilution with DI water for an additional 7 hours before the reaction. The quenched mixture was vacuum filtered onto a polyethersulfone (PES) membrane (pore size 5 μm) to separate the citric acid solution from the solid fraction containing carboxylated cotton fibers and residual acid. The citric acid collected from the first filtration was recovered by rotary evaporation and crystallization. DI water was gently added to the filter cake to rinse the remaining citric acid from the solid. The cake was washed until the conductivity of the filtrate was below 5 μS / cm. As a result, the washing solution from this process does not contain ions, and thus the product is in a neutral medium.

[0081] Textile fragments composed of a mixed fabric (polyester-cotton or acrylic-cotton) were cut into square small pieces with side lengths < 1 cm. 60 g of anhydrous citric acid was dissolved in 15 ml of water in a round-bottom flask to prepare an 80 wt% citric acid solution, and heated to > 80 °C using an oil bath. During heating, 195 mg of FeCl3 (equivalent to 0.02 mmol of FeCl3 per 1 g of citric acid) was added to the solution. 2 g of the square small pieces were added to the flask, and the reaction was carried out for 6 hours while mixing at 400 rpm using a mechanical stirrer. After 6 hours, the reaction was quenched by the addition of approximately 200 ml of deionized water and left to cool to ambient temperature. Longer fibers and a milky suspension were observed. The longer fibers (mainly composed of either polyester or acrylic fibers) were separated from the milky suspension using a 250 μm mesh and thoroughly washed with DI water. The suspended particles were sedimented and washed by continuous centrifugation cycles until the conductivity reached below 5 μS / cm.

[0082] The filtration cake of carboxylated cotton fabric was diluted with DI water to a concentration of about 2 wt% regardless of the textile source and then dispersed in DI water. Figure 3 shows a scheme of the citric acid-mediated hydrolysis of cotton-based textiles.

[0083] Processing of nanocellulose Regardless of the source textile, the resulting dispersion was neutralized by adding droplets of NaOH (aqueous solution, 1 M) until a pH of 7.0 was reached and then diluted to 1.0 wt% and fibrillated using a high-pressure microfluidizer (M-110EH, Microfluidics). Passage through 400 and 200 μm wide chambers connected in series was carried out 5 times at 1000 bar, followed by passage through 200 and 100 μm wide chambers 5 times at 1700 bar. After mechanical fibrillation, the resulting dispersion was centrifuged at 10,000 g for 10 minutes and vacuum filtered through a glass microfiber filter (Ahlstrom-Munksjo MGF grade, particle retention 0.7 μm) to remove traces of unfibrillated cotton. The final product was a colloidal dispersion of CNC with sodium-type surface carboxyl groups (-COONa).

[0084] Example 3 - Chemical pretreatment, procedure (iii): Tempo-mediated oxidation Textile samples made of 100% cotton or cotton blends with polyester, acrylic, wool, or elastane were cut into 5 cm square pieces. Oxidation of the textiles was carried out by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) mediation (10 mmol of hypochlorite per gram of cotton), and cleaning was performed by washing with distilled water (see Figure 3). The concentration of the textile in water was 1.5 - 2 wt%. NaClO was added dropwise, and at the same time, the pH was adjusted to 10 with 1 M NaOH and 0.5 M HCl if necessary. Note: If the target charge density is low or medium, the reaction will stop after a few minutes or hours (the color changes from yellow to white when all the chemicals are consumed). If the target charge density is 1.6 mmol COO- / g (high charge), the reaction can be quenched by adding deionized water after at least 4 hours. Until the end of the reaction, the chemicals were washed away by multiple cycles of deionized water and filtration until the conductivity was less than 5 - 10 μS and the pH was approximately 8 or at least less than 9.

[0085] Finally, the obtained cellulose was filtered and washed multiple times until the filtered solution became neutral.

[0086] To convert the oxidized cotton into nanocellulose disintegrates, ultrafine grinding was used. A 1 - 2 wt% suspension from the chemical treatment process was ground with a positive gap to avoid grinding on the grinding wheel. To achieve a nanoscale material forming the cellulose phase, the material was passed through the grinding wheel at least 10 times.

[0087] Example 4 - Processing of composites and filaments The carboxylated products (with or without fibrillation) from Procedure 2 and Procedure 3 are further used for pellet preparation by following the thermally induced phase separation method or oven drying method, which have been found to be efficient and alternative process routes.

[0088] Thermal Induced Phase Separation (TIPS): A masterbatch of composite spheres was prepared using the TIPS technique. This composite dispersion was added to a 20 ml syringe and manually extruded by dropping it into a liquid nitrogen bath at a distance of 5 cm. To prevent aggregation of the microspheres, each droplet was equilibrated to the liquid nitrogen temperature before adding additional droplets; the equilibration was clearly distinguishable by sedimentation. The droplets solidified upon contact with the liquid nitrogen to form spheres; these were placed in a freezer overnight and then lyophilized for 24 hours.

[0089] Oven Drying: Alternatively, the textile (2 wt%) in the chemically treated aqueous dispersion was dispersed for 20 minutes using a High-Shear Dispermix (Ystral GmbH, Germany). The resulting dispersion was cast into a film with a thickness of 1 - 2 cm and dried overnight in an oven at 60 °C. The dried film was cut into small square pellets (1 cm x 1 cm) using a commercially available paper cutter, followed by a thermo-mechanical process.

[0090] Example 5 - Filament processing · Biaxial screw extrusion was performed at 225 - 250 °C using the fine powder derived from the pellets.

[0091] Example 6 - 3D printing of footwear Printer: Ultimaker S5 (Ultimaker BV, Netherlands).

[0092] TIFF2025522854000002.tif139128 (Table 1) Printing parameters for 3D printing the sole and strap of footwear

[0093] The strap and sole were printed separately. Both were printed according to the printing parameters presented in Table 1. The only difference was the printing speed of the strap, which was set at 50 mm / s.

[0094] Using 25% polycotton / 75% TPU, test specimens for compression testing were printed with this filament in accordance with Standard Test Method for Compressive Properties of Rigid Plastics D695-15. In accordance with the same standard, that is, a rectangular parallelepiped with dimensions 12.7 x 12.7 x 25.4 mm and a printed infill density of 10%, the model was designed and printed. The test specimens were cut from a mesh sole with a corresponding balanced porous structure. At 30% compression, the compression strength of the non-porous test specimens was approximately 6 MPa, and that of the porous test specimens was approximately 2 MPa.

[0095] Example 7 - 3D printing of water treatment filters 3D printing: Multiple different models were 3D printed: (i) a rectangular parallelepiped model of standard size (25.4 × 12.7 × 12.7 mm) used for compression testing; (ii) cube filter models (20 × 20 × 20 mm) for adsorption testing with various pore structures, namely pore structures of 1 mm, 2 mm, and 3 mm. All prototypes were based on computer-aided design (CAD) models of cubes and cylinders. The printing parameters used for both custom-made filaments and commercially available reference filaments were as follows: nozzle diameter 600 μm, printing bed temperature 90 °C, printing speed 25 mm / s, layer thickness 150 μm, shell thickness 500 μm, infill density: 20% - 95% (depending on the model), infill distance: 0.1 - 3 mm (depending on the model). The printing temperature was set at 250 °C for both filaments used.

[0096] Compression test: A compression test was performed on 3D-printed rectangular parallelepiped specimens (12.7 × 12.7 × 25.4 mm) in accordance with Standard Test Method D695-15. A 10 kN load cell and a compression rate of 1 mm / min were applied until 60% deformation was reached. The apparent compression modulus was calculated from the slope of the linear elastic part of the stress-strain curve without considering the plateau and densification regimes. Energy dissipation, i.e., the toughness of the sample, was calculated considering the area under the stress-strain curve. The porous composite filter exhibited a compression modulus of 350 ± 39 MPa and a toughness of 10.6 ± 0.5 J / m 3 .

[0097] Dye adsorption: 3D-printed filters were tested for the removal of methylene blue (MB) from water. The removal efficiency was evaluated using a colorimetric method (λ max = 664 nm) with a UV-Vis spectrophotometer (Genesys (trademark), 40 / 50, ThermoFisher). The filters were shown to be very effective in removing MB from water after 24 hours of immersion (removal efficiency of approximately 80% at 10 mg l -1 ), and according to the results obtained, the pure PET filters showed only a 10% removal efficiency after 24 hours of immersion, indicating that the oxidized nanofibers were the main adsorption component of the developed filters.

[0098] Example 8 - Chemical properties of the cellulose fraction in the composite Figure 4 shows the chemical functional groups of cellulose derived from route ii. The FTIR of cotton with added citric acid shows a broad peak in the range of 1670 - 1770 cm -1 corresponding to the C=O stretching vibration band 58,61 (Figure 4). In addition, the band centered at 1590 cm -1 corresponds to the asymmetric stretching of the -CO2 - group, and the band (1725 cm -1The ester C=O vibration centered around) can also be visually recognized. These two peaks suggest that the esterification of cellulose was successful and that the carboxyl groups were covalently bonded to the cotton. The total amount of carboxylate in the cotton with added citric acid was 1.1 mmol / g as determined by titration. Approximately 63% of the carboxyl groups were derived from monoester bonds and 37% were from diesters.

[0099] Chemical functional groups of cellulose derived from route iii. The presence of carboxyl groups was confirmed by FTIR. The FTIR spectrum of polycotton contains characteristic peaks of both cotton and PET, while the spectra of oxidized polycotton and dry polycotton pellets contain one extra peak within the range of 1602 - 1633 cm -1 ; this can be attributed to the stretching vibration of the sodium carboxylate salt (COO - ) introduced after TEMPO-mediated oxidation. The charge density of oxidized polycotton was estimated to be 1.2 mmol COO - / 1 g of cellulose; this indicates that the reaction conditions resulted in highly charged cellulose fibers.

[0100] Therefore, the chemical pretreatment routes (ii) and (iii) have been successful in functionalizing cellulose in textiles and textile blends with chemical groups for ionic crosslinking or for interacting with waterborne contaminants. The chemical groups on the cellulose phase promote the occurrence of nanoscale fibrillation during thermomechanical processing.

[0101] Those skilled in the art will recognize that the present disclosure is not necessarily limited to the preferred embodiments described above. Those skilled in the art will further understand, for example, that modifications and variations are possible within the scope of the appended claims. Additionally, modifications to the disclosed embodiments can be understood and implemented by those skilled in the art who are actually practicing the claimed disclosure by considering the drawings, the present disclosure, and the appended claims.

Claims

1. A method for melt - processing textile waste materials, wherein the textile waste materials comprise (1) at least one thermoplastic polymer material such as polyurethane, polyester, nylon, cellulose, or elastane; and (2) at least one cellulose - containing material such as cotton textile, cotton blend with synthetic or natural polymers, regenerated cellulose - based textile and the method is adapted to prepare a composite material, (a) chemically pretreating the textile waste materials; (b) thermo - mechanically processing the chemically pretreated materials of step (a), including melt - compounding, and optionally adding recycled PET; plasticizers such as glycerol, PEG, and vegetable oils; and / or toughening polymers such as natural rubber and polyurethane comprising thereby obtaining a composite material comprising a well - dispersed polymer composite and / or nanocomposite, wherein the at least one thermoplastic polymer material essentially constitutes a matrix phase and the at least one cellulose - containing material essentially constitutes a reinforcing phase of the composite material, said method.

2. The chemical pretreatment is by the following routes: (i) partial dissolution of the at least one thermoplastic polymer material using 1:1 to 1:2 TFA (trifluoroacetic acid) and DCM (dichloromethane); (ii) optional citric acid hydrolysis of any cellulose occurring in the at least one thermoplastic polymer material and / or the at least one cellulose - containing material; and (iii) optional TEMPO - mediated oxidation of any cellulose occurring in the at least one thermoplastic polymer material and / or the at least one cellulose - containing material The method according to claim 1, selected from at least one of them.

3. After the chemical pretreatment by route (ii) and / or (iii), fibrillation using a mechanical process and (j) bead - processing using a thermally - induced phase separation method or (jj) an oven - drying method are carried out before the subsequent thermo - mechanical processing. The method according to claim 2.

4. The method according to any one of the preceding claims, wherein the textile waste materials are melt - processed at a temperature below 250°C at ambient pressure.

5. The method according to any one of the preceding claims, wherein the cellulose-containing material comprises a polymorph of cellulose I and / or cellulose II.

6. The method according to any one of the preceding claims, wherein the textile waste material is selected from textile clothes or shoes to be recycled; polyester blends; cotton blends containing polyester, elastane, cellulose, polyurethane, and / or nylon; shredded polycotton; and shredded acrylic cotton.

7. The method according to any one of claims 1 to 6, further comprising using the composite material obtained in step (b) for processing by injection molding, compression molding, or any other optional melt processing method, thereby obtaining a recycled product.

8. The method according to any one of claims 1 to 6, further comprising filament processing the composite material obtained in step (b), including filament extrusion to produce a 3D printable filament.

9. The method according to claim 8, further comprising using the 3D printable filament obtained for 3D printing, thereby obtaining a 3D printed recycled product.

10. A composite material comprising a well-dispersed polymer composite and / or nanocomposite, wherein (1) at least one thermoplastic polymer material essentially constitutes a matrix phase, and (2) at least one cellulose-containing material essentially constitutes a reinforcing phase of the composite material, and the at least one thermoplastic polymer and the at least one cellulose-containing material originate from the same textile waste material. The composite material.

11. The composite material according to claim 10, wherein the at least one thermoplastic polymer material originates from polyurethane, polyester, nylon, cellulose, or elastane, and the at least one cellulose-containing material originates from cotton textiles, cotton blends with synthetic or natural polymers, or recycled cellulose-based textiles.

12. (i) Recycled PET; (ii) plasticizers such as glycerol, PEG, and vegetable oils; and / or (iii) toughening polymers such as natural rubber and polyurethane The composite material according to claim 10 or 11, further comprising.

13. The composite material according to any one of claims 10 to 12, wherein the thermoplastic polymer is melt-processable at a temperature below 250 °C under ambient pressure.

14. The composite material according to any one of claims 10 to 13, wherein the cellulose-containing material comprises a polymorphic form of cellulose I and / or cellulose II.

15. Compared with the original textile waste material, (1) the thermoplastic polymer material is fractionated and the cellulose-containing polymer is intact, or (2) the thermoplastic polymer is intact and the cellulose-containing material is fractionated. The composite material according to any one of claims 10 to 14.

16. The composite material according to any one of claims 10 to 15, comprising nanoscale cellulose.

17. The composite material according to any one of claims 10 to 16, which is in the form of pellets.

18. A recycled product comprising the composite material according to any one of claims 10 to 17, further melt-processed by injection molding, compression molding, or any other melt-processing method.

19. A 3D printable filament comprising the composite material according to any one of claims 10 to 17, further filament-processed by filament extrusion for later use in 3D printing to obtain a 3D printed recycled product.

20. A 3D printed recycled product comprising the 3D printable filament according to claim 19, further 3D printed.

21. The 3D printed recycled product according to claim 20, selected from shoes, clothing, apparel, interior decoration products, accessories, or water filters.

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