WO2024062321A2

WO2024062321A2 - Recyclable thread and textiles made thereof

Info

Publication number: WO2024062321A2
Application number: PCT/IB2023/058843
Authority: WO
Inventors: Kadirvelan Raja SORNALINGAM; Ramkumar ALAGARSAMY; Ranganathan Srinivasan
Original assignee: J. & P. Coats Limited
Priority date: 2022-09-23
Filing date: 2023-09-07
Publication date: 2024-03-28
Also published as: WO2024062321A4; WO2024062321A3

Abstract

The present disclosure relates to a fully recyclable thread. The present disclosure also relates to high strength, biodegradable and fully recyclable thread having a structure including a core and a sheath. Further, the present disclosure relates to method of forming the fully recyclable thread comprising providing a thread core, a thread sheath, layering the thread sheath around the thread core; and twisting the layered thread sheath thread core together. The present disclosure provides a thread enabling a circular economy, enhance sustainability, reduce textile waste and suitable for industrial production.

Description

RECYCLABLE THREAD AND TEXTILES MADE THEREOF

FIELD OF THE INVENTION

[0001] The present invention relates in general to a high strength, recyclable thread and fabrics made therefrom, and in particular to a high strength, biodegradable and fully recyclable thread having a structure including a core and a sheath, the thread enabling a circular economy of for items made therefrom to enhance sustainability and reduce textile waste.

BACKGROUND OF THE INVENTION

[0002] The current system of producing, distributing and disposing of clothing occurs almost entirely in a linear ‘take-make-dispose’ model - that is, extracting virgin resources, using garments for a short period before disposing of them, whereby the materials are lost to landfill or incineration. In fact, over 70% of clothing discarded ends up in landfill or incineration, with less than 1% being incorporated in the production of new textiles. To put that into perspective, the rate of disposal is equivalent to one garbage truck of textile waste being landfilled every second. This problem is exacerbated given the fact that over half of the textiles produced today are from synthetic fibers, which are conventionally not biodegradable and have been found to shed microfibers into the surrounding environment.

[0003] The recycling of textile waste that does occur consists of cascading the waste to other industries in the production of lower value applications - such as insulation, mattress stuffing and industrial wipes. The sheer quantity of textile waste being generated is further increasing given the underutilization of clothing. For example, the emergence of fast fashion and falling costs has meant that clothing production has doubled from 2000 to 2014. In today’s trend-driven system, consumers keep clothing items about half as long as they did 15 years ago. It has been estimated that over half of fast fashion items produced are disposed of within one year --- leading to an extreme throwaway culture. The consequence of all of the highlighted converging factors is a huge amount of non-reusable textile waste that is destined for landfill or incineration at large environmental cost. [0004] In order to achieve suitable material properties such as strength and durability, many textiles are formed of or include non-recyclable materials. For example, many garments are formed of cotton with at least 2% nylon, making the garment non-recycable.

[0005] Man-made cellulosic fibers (MMCF) are a group of fibers that are conventionally derived primarily from wood, and in some cases other sources of cellulose, such as bamboo or other plant matter. Cellulose is found in the walls of plant cells, helping plants and trees to stay upright. It is also a key component of cotton fibers, in which it is found in extremely pure form. Coton is an example of a ‘natural’ cellulose fiber and is processed differently from MMCF - with the latter following a dissolution and extrusion process, thus being referred to as ‘manmade’. In the majority of MMCF production, wood is mechanically shredded and then processed multiple times into sheets of cellulosic ‘pulp’. These sheets are then dissolved to form a viscose solution, which is extruded through spinnerets in a wet spinning process into fiber.

[0006] MMCF production has great potential from a sustainability perspective; moving production away from oil-derived synthetic fibers and reducing the depletion of freshwater through reduced cotton cultivation. Furthermore, MMCF commands considerably less landusage than cotton, as well as no pesticides or insecticides. However, imperative to the sustainability credentials are responsible sourcing practices and production processes, such as replanting forests at a faster rate than harvesting, and recovering the chemicals used in production in a closed-loop manner.

[0007] Central to the sustainability credentials of MMCF are responsible sourcing practices and production processes; ensuring that harvesting of trees is done at a replenishable rate and closed-loop processes are used. Despite improvements, environmental organization Canopy estimates that approximately one third of MMCF is procured from ancient and endangered forests - posing a grave threat to the environment and our ecosystems. Moreover, on the demand side, the fashion system that MMCF enters into is predicated upon a linear system; extracting virgin resources for production and disposing of textiles after a short amount of use - generating huge amounts of waste.

[0008] Strides have been made in laying out a future system - one that is regenerative and replaces the use of virgin wood coming from ancient & endangered forests with responsible forestry and alternative fiber sources - namely waste cotton textiles and other agricultural residue. Cotton textiles provide a fantastic source of cellulose to be regenerated into new MMCF fibers - requiring only 1 ton of cotton waste input to produce 1 ton of MMCF output, compared with 2.5 - 3 tons of conventional wood input. This opportunity is unique and cannot be understated; if just 25% of the cotton and rayon textile waste was converted into regenerated MMCF, the need for virgin wood fiber in viscose production would be eradicated.

[0009] Textile recycling technologies provide an encouraging solution to close the loop on MMCF production, alleviating the burden on virgin resources and reducing textile waste. Two key forms of textile recycling exist; mechanical and chemical. Mechanical recycling is a more established industry, with roots in the ‘downcycling’ industry - that is, producing materials used in insulation, industrial clothes or other lower-value uses. Mechanical recycling of textiles into new textiles is commonly done on high purity, long staple fibers such as wool and cashmere. The mechanical recycling process involves breaking down garments by chopping them into shredded fragments, pulling apart the fibers and then disentangling and aligning them using a carding process. Inherent to the mechanical recycling process is the shortening of the fibers, reducing their performance during the yarn and fabric production. This makes it challenging to achieve the desired versatility and quality of finished garments using mechanically recycled fibers. It can therefore be argued that mechanical recycling of cotton does not provide a ‘truly circular’ solution given the continued degradation of fiber lengths in each cycle. To combat this, the recycled cotton fibers are often blended with virgin ones, improving the performance but worsening the environmental footprint of the final output.

[0010] Moreover, textile-to-textile mechanical recycling solutions require a high purity of feedstock. The low tolerance for contamination of other fibers is especially problematic given the high prevalence of blended fabrics entering the post-consumer waste stream - with research from the Netherlands estimating it to be around 40% of post-consumer textiles. Finally, given mechanical recycling does not change the color of the garments, they must be manually sorted into groups of colors, increasing labor costs to the process. Given all of the above, it could be said that textile-to-textile mechanical recycling has greater applicability to the post-industrial (rather than post-consumer) textile waste stream - whereby there is greater assurance of homogeneity of feedstock in terms of purity and color.

[0011] On the other hand, chemical recycling of textile waste provides an encouraging alternative as it is able to overcome some of mechanical recycling’s shortcomings. From a process perspective, cheniicai recycling breaks down the fibers into their chemical building blocks, then rebuilds them into new fibers of indistinguishable, or even superior quality. Emerging chemical recycling technologies are also able to address blended-fiber garments. For example, polyester and cotton possess very different solubility characteristics, allowing for chemical recycling to separate and extract both fibers in a polycotton blend. Specifically, to cotton, which accounts for almost a quarter of the global fiber market, the process generally involves dissolving the cotton cellulose in a solvent and then wet spinning new fibers from the resulting pulp, in a similar way to the conventional viscose process and other man-made cellulosic fibers.

[0012] Whilst the technology holds great potential to close the loop on much of the textile waste, it still has a few crucial barriers to scale. First, aside from a few examples, investors have not demonstrated great appetite in the space, with the investments being perceived as too risky given the high capex costs and the long timeframe to commercialization. Moreover, the perceived risk of the technology is compounded by the lack of formalized brand engagement with innovators - on the whole there seldom exists offtake agreements and other codevelopment contracts. Without the demand for the offtake signaled, it is challenging to attract financiers into the space.

[0013] Thus, there exists a need for a high strength, biodegradable and recyclable thread that enables a circular economy of for items made therefrom to enhance sustainability and reduce textile waste.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0015] FIG. 1 A is a perspective schematic drawing of a fully recyclable thread according to embodiments of the present invention;

[0016] FIG. IB is a cross-sectional schematic drawing of a fully recyclable thread according to embodiments of the present invention; [0017] FIG. 1C is a partial cut-away perspective view of a fully recyclable thread according to embodiments of the present invention;

[0018] FIG. 2 is an SEM image of a cross-section of an embodiment of the fully recyclable thread at 250 times resolution;

[0019] FIG. 3 is an SEM image of a cross-section of an embodiment of the fully recyclable thread at 500 times resolution;

[0020] FIG. 4 is an SEM image of a cross-section of an embodiment of the fully recyclable thread at 1000 times resolution;

[0021] FIG. 5 is an SEM image of a cross-section of a single thread of the fully recyclable thread at 1000 times resolution;

[0022] FIG. 6 is an SEM image of a cross-section of a single thread of the fully recyclable thread at 1000 times resolution;

[0023] FIG. 7 is an SEM image of an embodiment of the composite thread along its longitudinal axis at 100 times resolution; and

[0024] FIG. 8 is an SEM image of an embodiment of the composite thread along its longitudinal axis at 250 times resolution.

DESCRIPTION OF THE INVENTION

[0025] The present invention has utility as a high strength, biodegradable and fully recyclable thread having a structure including a core and a sheath, the thread enabling a circular economy of for items made therefrom to enhance sustainability and reduce textile waste.

[0026] The present invention will now be described with reference to the following embodiments. As is apparent by these descriptions, this invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, features illustrated with respect to one embodiment can be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from the embodiment. In addition, numerous variations and additions to the embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant invention. Hence, the following specification is intended to illustrate some particular embodiments of the invention, and not to exhaustively specify all permutations, combinations, and variations thereof.

[0027] It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range of from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0029] Unless indicated otherwise, explicitly or by context, the following terms are used herein as set forth below.

[0030] As used in the description of the invention and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0031] Also as used herein, “and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).

[0032] According to embodiments, a high strength, biodegradable, and fully recyclable thread is provided for forming textiles therefrom. As shown in FIG. 1A, embodiments of the fully recyclable thread 10 is formed of a thread core 12 and a thread sheath 14 surrounding the thread core 12. According to inventive embodiments, the thread core 12 and the thread sheath 14 are both formed of a man-made cellulosic fiber (MMCF).

[0033] According to some inventive embodiments, the MMCF is lyocell. Lyocell fibers are staple fibers produced from the natural cellulose in harvested wood pulp using a totally recycled solvent spinning technique. These are man-made fibers, but natural in origin. Lyocell is versatile and combines exceptional strength, launderability and low fabric shrinkage with all the benefits of an exceptional hand, drape, color intensity, luster, absorbency and biodegradability normally associated with cellulosics. It is twisted or spun into yarns and woven or knitted in to fabrics or garments. According to embodiments, the lyocell fibers are staple fiber produced from the natural cellulose in harvested wood pulp using a totally recycled solvent spinning technique. The lyocell fibers are versatile and combine exceptional strength, launderability and low fabric shrinkage with all the benefits of an exceptional hand, drape, color intensity, luster, absorbency and biodegradability normally associated with cellulosics. The lyocell may include a peachskin finish and feel with a soft dusty surface which is the light reflecting off small hairs on the surface of the fabric, or the fibers may be silky, smooth and lustrous. The lyocell fibers excellent dye uptake and colour stability, extremely high tensile strength in woven and knitted fabrics, very good launderability, and a clear stitch construction when used in woven and knitted fabrics. These lyocell fibers have a linear denisty (dtex) of 1.7, a tenacity (cN/tex) or 42-44, an elongation % of 14-16, a wet tenacity (cN/tex) of 37-41, a wet elongation % of 16-18, a wet modulous at 5% extension (cN/tex) of 270, and a water imbibitions % of 65. According to embodiments, the lyocell includes virgin cellulose, recycled cellulose, or a combination thereof.

[0034] According to some inventive embodiments, the MMCF is at least partially formed of sustainable wood pulp. According to some inventive embodiments, the MMCF is at least partially formed of cellulosic pulp produced from textile waste, agricultural waste, microbial cellulose, or a combination thereof. According to other inventive embodiments, the MMCF is at least partially formed from food waste.

[0035] The unique method and technique of mechanically combining these fibers in certain weight percentage ranges disclosed herein produces a thread that provides the unique combination of enhanced properties described above, including the ability to be fully recycled and biodegradable while still affording a high strength comparable to that of synthetic materials that are otherwise not fully recyclable. According to some inventive embodiments, the thread core and the thread sheath are present in a ratio of 60-90:40-10 wt./wt. In some inventive embodiments, the thread core has a linear density between 85 to 280 dtex. According to embodiments, the inventive thread has total denier of between 125 to 485 dtex.

[0036] In some inventive embodiments, the thread core fibers are continuous fibers. In some inventive embodiments, the thread sheath fibers are continuous or have a length that is less than 65 mm long, and in some embodiments between 35-55 mm long. As such, the comfort of a textile made therefrom is improved. According to some inventive embodiments, the single-ply core fibers each are spun with a Z-twist. Additionally, the single -ply sheath fibers are each spun with a Z-twist. The final two-ply thread is spun with an S-twist.

[0037] Due to the unique structure of the thread, the thread has improved higher strength and higher tenacity as compared to conventional spun recyclable threads. According to some inventive embodiments, the thread has a filament strength of at least 600 cN. According to further inventive embodiments, the thread has a filament strength of at least 1100 cN.

[0038] According to specific embodiments of the present invention, fibers are selected with the most desired properties. These fibers are then mechanically combined to form the inventive thread. These inventive threads yield enhanced desired properties beyond the desired properties of the fibers alone. Weaving and knitting patterns can also produce further enhancement of desired properties.

[0039] The strength and characteristics of the final textile material depend fundamentally on the nature of the fiber, then how fibers are arranged into thread, and the structure of the fabric. An inventive thread, based on the fiber lengths used in the thread core and sheath, and the nature of the twist processing, has properties imparting to a textile or garment formed therefrom that have not previously been available.

[0040] Understanding the fundamental properties of a plurality of fibers and threads formed thereof and then uniquely arranging the fibers mechanically offers a thread with the desired properties of the plurality of fibers which then allows fabrics, woven and knitted, to leverage those desired properties. The additional mechanical properties of the weaving and knitting process, i.e. different patterns of weaves and knits, can further enhance the desired properties. [0041] As shown in FIGS. 1A-1C, embodiments of an inventive fully recyclable thread 10 include a thread core 12 and a thread sheath 14 surrounding the core 12. The core 12 is formed of continuous staple fibers, that is fibers that are geometrically characterized as having a very high length-to-diameter ratio. Fiber diameters generally range between 3-200 pm, depending upon the fiber. According to embodiments, the MMCF staple fibers are twisted and used as a thread core 12 of the inventive thread 10. The thread core 12 with same direction twisting under controlled conditions with the sheath 14 achieves properties not previously available and distinct from either MMCF alone when those materials make up the core and sheath, respectively. [0042] According to embodiments, the staple that makes the thread core 12 has a linear density of at least 85 dtex and up to 280 dtex or more depending on the type of material used. According to some inventive embodiments, the thread core 12 is an untwisted yarn or twisted yarn construction. According to embodiments, the core features a Z-twist. According to embodiments, the core has a special surface treatment provided thereon that adds functionalities to the core. These functionalities improve the product performance in an application and/or the processability. Examples of this include the application of the waterblocking finish or an adhesion activation finish.

[0043] According to embodiments, the MMCF staple fibers are twisted into a yarn that is used as the sheath 14 of the thread 10. According to embodiments, the MMCF of the sheath is a spun yarn. According to embodiments, the MMCF sheath staple fibers feature a Z-twist.

[0044] According to embodiments, the core 12 is thickly covered with sheath fibers to form a sheath 14 thereon. The sheath 14 thickly covers the core 12, thereby enhancing the strength of the inventive thread 10. Given that the core 12 and the sheath 14 are formed of like materials, i.e. both formed of MMCF, the inventive thread 10 and textiles formed thereof can be easily recycled without a need to pre-sort different materials.

[0045] According to embodiments, the inventive thread 10 has a linear density of between Nm 50/2 and Nm 20; and between 500 and 1200 twists per meter (TPM). According to embodiments, the twists are all in the same direction, which according to embodiments, is in the S direction, while according to other embodiments is in the Z direction. It is appreciated an overtwisting is often required, especially in S -direction twisted thread 10 to compensate of the twist loosening in response to the internal tension created through the twisting process.

[0046] According to embodiments, the inventive fully recyclable thread 10 exhibits a high tenacity. Tenacity is defined herein as the ratio of tensile strength to yarn size. Tenacity is calculated using the ultimate breaking force of the yarn (when a thread or yarn is stretched to its breaking point) and the linear density and can be used to compare dissimilar material or different sizes of material. According to some inventive embodiments, the inventive thread has a tenacity of 2.5 to 5.0 cN/tex. According to still other inventive embodiments, the inventive thread has a breaking strength of 700 to 1300 cN. According to embodiments, the inventive thread has a 5 to 15 % elongation. [0047] According to some inventive embodiments, the thread 10 may include a cover that covers the sheath 14 of the thread 10. According to embodiments, the cover is formed of recycled cotton, BCI cotton, organic cotton, or a combination thereof.

[0048] According to inventive embodiments, the thread 10 is dyable to a variety of colors. According to embodiments, the inventive thread 10 is dyed using a natural dye. According to embodiments, the inventive thread 10 is dyed using a natural indigo dye. According to embodiments, the inventive thread is dyed using a cradle to cradle dye. According to embodiments, the thread is dyed during polymerization or formation of the thread, thereby saving the time and processing steps, associated pollution and costs of a separate dying operation. According to embodiments, the inventive thread is treated with a surface treatment of chemicals or plasma for the purpose of increasing the affinity of a dye applied thereto.

[0049] Some inventive properties are detailed below in Table 1

[0050] Table 1. Tenacity and strength of various ratios of core-to-cover

1 Single thread 60 core:40 cover 28 365

2 Single thread 90 core: 10 cover 32 425

3 Single thread outside the 58 core:42 cover 27.5 350 proposed ratio

4 With different cover (BCI cotton) 90 core: 10 cover 30 400

5 Z twisted (2 Ply threads) 85 core: 15 cover 30 775

[0051] The present invention is further detailed with respect to the following examples. These examples are not intended to limit the scope of the appended claims.

Example 1

[0052] An inventive thread is prepared from lyocell. The thread has a core and a sheath applied thereto. The spun lyocell thread has a tkt. of 120 and a tex 24. The resulting thread is then tested to determine nominal grist, sizing, strength, tenacity, % elongation, and TPI. It is found that the nominal grist is between 240 and 310, the sizing is between 100 and 150 dtex, the strength is between 690 and 1,300 cN, the tenacity is between 20 and 50 cN/tex or 2 and 6 g/den, the % elongation is between 6 and 20 %, and the TPI is between 18 and 30. [0053] Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference. [0054] The foregoing description is illustrative of particular embodiments of the invention but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.

Claims

WE CLAIM:

1. A fully recyclable thread comprising: a thread core (12); and a thread sheath surrounding the core (14); wherein the thread core and the thread sheath are both formed of a man-made cellulosic fiber (MMCF).

2. The fully recyclable thread of claim 1 wherein the thread core and the thread sheath are joined by unique core spun technology using ring spinning, modified ring spinning, compact spinning, siro spinning, vortex spinning and air jet spinning technologies.

3. The fully recyclable thread of any one of claims 1 to 2 wherein the thread is dyeable

4. The fully recyclable thread of any one of claims 1 to 3 wherein the thread has a filament strength of a range from 600 cN to 2400 cN based on the constructions and thickness of the material.

5. The fully recyclable thread of any one of claims 1 to 4 wherein the thread core and the thread sheath are present in a ratio between 60 to 90 % and 40 to 10 %.

6. The fully recyclable thread of any one of claims 1 to 5 wherein the thread core and the thread sheath are both twisted in the Z-direction.

7. The fully recyclable thread of any one of claims 1 to 6 wherein the thread core and the thread core and the thread sheath are both twisted in the S -direction.

8. The fully recyclable thread of any one of claims 1 to 7 wherein the thread has a tenacity of from 3 to 8.5 grams per denier.

9. The fully recyclable thread of any one of claims 1 to 8 wherein the MMCF is lyocell.

10. The fully recyclable thread of claim 9 wherein the lyocell includes virgin cellulose.

11. The fully recyclable thread of claim 9 wherein the lyocell includes recycled cellulose.

12. The fully recyclable thread of any one of claims 1 to 8 wherein the MMCF is at least partially formed of sustainable wood pulp.

13. The fully recyclable thread of any one of claims 1 to 8 wherein the MMCF is at least partially formed of cellulosic pulp produced from textile waste, agricultural waste, microbial cellulose, or a combination thereof.

14. The fully recyclable thread of any one of claims 1 to 8 wherein the MMCF is at least partially formed from food waste.

15. The fully recyclable thread of any one of claims 1 to 14 further comprising a cover that covers the thread sheath.

16. The fully recyclable thread of claim 15 wherein the cover is formed of recycled cotton, BCI cotton, organic cotton, or a combination thereof.

17. The fully recyclable thread of any one of claims 1 to 16 wherein the fully recyclable thread has between 500 and 1200 twists per meter (TPM).

18. A method of forming the fully recyclable thread of claim 1, the method comprising: providing a thread core; providing a thread sheath; layering the thread sheath around the thread core; and twisting the layered thread sheath thread core together.

19. The method of claim 18 further comprising applying a surface treatment to the fully recyclable thread.

20. The method of any one of claims 18 or 19 further comprising dyeing the fully recyclable thread using a natural dye.

21. The method of any one of claims 18 to 20 further comprising applying a bio-based lubricant to the fully recyclable thread.

22. The method any one of claims 18 to 21 wherein at least one of the core thread or the sheath thread are derived from sustainable source of at least one of: wood pulp, textile waste, agricultural waste, food waste, chemically modified wood pulp using ionic liquids or any other waste stream which consists of cellulose rich content.

23. The method of claim 22 wherein both the core thread and the sheath thread are derived from the sustainable source.

24. The method of claim 23 wherein the core thread and the sheath thread are derived from a single one of the sustainable source.

25. The method of claim 23 wherein the core thread and the sheath t read are derived each from different types of the sustainable source.

26. Use of the thread of any one of claims 1 to 18 to form a fabric or a garment from the fabric.

27. The use of claim 26 wherein the garment is formed without synthetic sewing thread.

28. The use of claim 27 further comprising recycling the garment.

29. The fully recyclable thread of any one of claims 1 to 17 wherein the thread is finished with antistatic, anti-microbial and flame retardant finishes.

30. The fully recyclable thread of any one of claims 1 to 17 wherein the thread is coated with abrasion resistance improvement chemicals.

31. The fully recyclable thread of any one of claims 1 to 17 wherein the thread is coated with bio enzymes to improve hairiness.

32. The fully recyclable thread of any one of claims 1 to 17 wherein the thread includes a blend of fire-resistant fibers.