EP-4735512-A2 - PROCESS FOR MIXED FABRIC REJUVINATION

Abstract

The invention pertains to a method for mixed fabric fiber rejuvenation, wherein the method comprises the steps of adding ethylene glycol (EG) in gas phase at a temperature of between 190° to 250° C trough vapour injection to a fabric fibre material comprising polyester and natural fibre material, whereby at least partly depolymerising the polyester material to monomeric and oligomeric polyester residues, the monomeric and oligomeric polyester residues being dissolved in condensed, excess of liquid EG; optionally adding liquid phase EG, recovering a solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG, and an essentially polyester-free natural fibre as a solid product; and optionally separating the solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG, from the solid product, comprising essentially polyester-free natural fibre. Further is provided a system 100 for mixed fabric fiber rejuvenation of a mixed fabric fibre material comprising polyester and natural fibre material.

Inventors

• WENE, Henrik
• JAKOBSSON, Niklas

Assignees

• Rewin Textiles AB

Dates

Publication Date

20260506

Application Date

20240506

Claims (1)

1. CLAIMS 1. A method for mixed fabric fiber rejuvenation, wherein the method comprises the steps of: - adding ethylene glycol (EG) in gas phase at a temperature of between 190° to 250° C trough vapour injection to a fabric fibre material comprising polyester and natural fibre material, whereby at least partly depolymerising the polyester material to monomeric and oligomeric polyester residues, the monomeric and oligomeric polyester residues being dissolved in condensed, excess of liquid EG; - optionally adding liquid phase EG, - recovering a solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG, and an essentially polyester-free natural fibre as a solid product; and - optionally separating the solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG, from the solid product, comprising essentially polyester-free natural fibre. 2. The method according to claim 1, wherein the monomeric polyester residues are bis(hydroxy ethyl) terephthalate (BHET). 3. The method according to any one of claims 1 to 2, wherein the temperature of the EG vapour injection is between 195 °C and 240 °C. 4. The method according to any one of claims 1 to 3, wherein the temperature of the EG vapour injection is between 197 °C and 220 °C. 5. The method according to any one of claims 1 to 4, wherein a gas phase is withdrawn, and separating any non-EG components in the gas phase from EG and reintroducing the separated EG to the fabric fibre material comprising polyester and natural fibre material, whereby the EG in the gas phase is recycled. 6. The method according to claim 5, wherein the EG in the gas phase is continuously recycled. 7. The method according to any one of claims 5 to 6, wherein non-EG components in the gas phase are separated from EG by condensation. 8. The method according to any one of claims 1 to 7, wherein the solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG is separated from the solid product, comprising essentially polyester-free natural fibre, preferably through filtering. 9. The method according to any one of claims 1 to 8, wherein the recovered liquid solvent phase is cooled to a temperature of 100° C to 140° C and filtered, whereby contaminants with higher precipitation temperatures than monomeric and oligomeric polyester residues are separated from the solvent phase comprising monomeric and oligomeric polyester residues and EG. 10. The method according to any one of claims 1 to 8, wherein the recovered solvent phase is cooled down to a temperature of less than 50 °C, such as between 10 to 50 °C, thereby precipitating monomeric and oligomeric polyester residues, and thereafter separating the precipitated monomeric and oligomeric polyester residues from the solvent phase. 11. The method according to any one of claims 1 to 10, wherein a portion of the EG in the recovered solvent phase is evaporated to generate EG vapour, thereby concentrating the monomeric and oligomeric polyester residues in the solvent phase. 12. The method according to claim 1 to 11, wherein a portion of the EG in the recovered solvent phase is reclaimed through distillation, thereby concentrating monomeric and oligomeric polyester residues in the solvent phase and generating EG vapour. 13. The method according to claim 11 or 12, wherein the evaporation or distillation takes place at a superatmospheric pressure to generate ethylene glycol (EG) in gas phase at a temperature of between 190° to 250° C, and wherein the generated EG vapour is used for vapour injection to the fabric fibre material comprising polyester and natural fibre material. 14. The method according to any one of claims 1 to 13, wherein the mixed fabric fiber, the gas phase and the solvent phase are agitated to ensure an even temperature distribution during the depolymerization. 15. The method according to any one of claims 1 to 14, wherein the resulting essentially polyester-free natural fibre is washed to remove monomeric and oligomeric polyester residues to obtain a purified natural fiber. 16. The method according to any one of claims 1 to 15, wherein the natural fibre material comprises fibers that are more hygroscopic than polyester fibers. 17. The method according to any one of claims 1 to 16, wherein the natural fibre material are selected from the group consisting of plant-based materials, such as cotton, linen, bamboo, and jute, man-made cellulosic fibers, such as viscose and lyocell, animal-based fibers, such as silk and wool; preferably the natural fiber material is cotton. 18. The method according to any one of claims 1 to 17, wherein the percentage of natural fiber in the mixed fabric fiber is at least 1 wt.-%, such as at least 5 wt.-%, such as at least 10 wt.-%, such as at least 20 wt.-%, such as at least 50 wt.-%, such as between 1 wt.-% to 99 wt.-%, such as between 5 wt.-% to 95 wt.-%, such as between 1 to 50 wt.% or between 50 wt.-% and 99 wt.-%. 19. The method according to any one of claims 1 to 18, wherein the percentage of polyester in the mixed fabric fiber is at least 1 wt.-%, such as at least 5 wt.-%, such as at least 20 wt.-%, such as at least 50 wt.-%, such as from between 1 wt.-% to 99 wt.-%, such as from between 5 wt.-% to 95 wt.-%, such as between 1 to 50 wt.% or between 50 wt.-% and 99 wt.-%. 20. The method according to any one of claims 1 to 19, wherein the heat is provided through the injected EG vapour. 21. The method according to any one of claims 1 to 19, wherein additional heat is added in the method through additional heats sources, such as through pre-heating of the mixed fabric fiber and/or optional liquid EG, or through use of an external heat source, such a heat mantle or use of micro-waves. 22. The method according to any one of claims 1 to 21, wherein the method is run in batches. 23. The method according to any one of claims 1 to 22, wherein the monomeric polyester residue level in the solvent phase is monitored, a stabile monomeric polyester residue:EG ratio in the solvent phase indicating that all polyester has been depolymerized, whereby the solvent phase and the essentially polyester-free natural fibre is recovered. 24. The method according to any one of claims 1 to 23, wherein the mass ratio (wt./wt.) between polyester and EG is in the range of 1 :3 to 1 :9, preferably 1 :3.7 to 1 :6, more preferably 1 :4 to 1 :5. 25. A system (100) for mixed fabric fiber rejuvenation of a mixed fabric fibre material comprising polyester and natural fibre material, the system comprising at least one depolymerization vessel (1) for at least partly depolymerising the polyester to monomeric and oligomeric polyester residues, wherein the depolymerization vessel (1) comprises; at least one feed inlet (2) for feeding a mixed fabric fiber material comprising polyester and natural fiber material to the vessel, at least one EG vapour inlet (3) for injecting EG in gas phase at a temperature of between 190° to 250° C into the vessel, at least one EG liquid inlet (4) for injecting liquid EG into the vessel, and at least one outlet (5) for recovering monomeric and oligomeric polyester residues, unreacted EG and essentially polyester-free natural fiber material. 26. A system (100) according to claim 25, wherein the depolymerization vessel (1) may be operated at atmospheric pressure or superatmospheric pressure. 27. The system (100) according to claim 25 to 26, further comprising a vapour phase recycling column (6) and a partial condenser (24) for separating any non-EG components in a gas phase from EG by condensing EG, wherein the depolymerization vessel (1) further comprises; at least one gas outlet (7) for removing the gas phase, at least one EG inlet (8) for reintroducing separated liquid EG, whereby the EG in the gas phase is recycled, wherein the vapour phase recycling column (6) comprises; at least one gas inlet (9) connected to the gas outlet (7) of the depolymerization vessel (1), at least one EG liquid outlet (10) connected to the EG liquid inlet (8) depolymerization vessel (1), a gas outlet (25), a liquid inlet (26), and wherein the partial condenser (24) comprises; at least one gas inlet (27) connected to the gas outlet (25) of the vapour phase recycling column (6), at least one EG liquid outlet (28) connected to the liquid inlet (26) of the vapour phase recycling column (6), and at least one non-EG gas outlet (11) for removal of any non-EG components. 28. The system (100) according to any one of claims 25 to 27, further comprising a separation means (12) for separating a solvent phase comprising the monomeric and oligomeric polyester residues and unreacted EG from a solid product comprising an essentially polyester-free natural fiber, the separation means (12) comprising an inlet (13) connected to the outlet (5) of the depolymerization vessel (1), a solvent outlet (14) and a solids outlet (15). 29. The system (100) according to claim 28, wherein the separation means (12) is a filter. 30. The system (100) according to any one of claims 28 to 29, further comprising at least one contaminant precipitation vessel (29) for cooling the recovered liquid solvent phase and precipitating contaminants with higher precipitation temperatures than the monomeric and oligomeric polyester residues from the solvent phase, comprising an inlet (30) connected, directly or indirectly, to the solvent outlet (14) of the separation means (12), a solvent outlet (31) and a precipitant outlet (32) for contaminants with higher precipitation temperatures than the monomeric and oligomeric polyester residues; preferably the contaminant precipitation vessel (29) is arranged downstream of the separation means (12). 31. The system (100) according to any one of claims 28 to 30, further comprising at least one precipitation and separation vessel (16), for precipitating monomeric and oligomeric polyester residues, and for separating said precipitated monomeric and oligomeric polyester residues from the solvent phase, the precipitation and separation vessel (16) comprising an inlet (17) connected, directly or indirectly, to the solvent outlet (14) of the precipitation means (12), a solvent outlet (18) and a precipitant outlet (19). 32. The system (100) according to any one of claims 28 to 31, further comprising an EG recycling column (20), for generating EG vapour and concentrating any remaining monomeric and oligomeric polyester residues, comprising a liquid phase inlet (21), an EG vapour outlet (22) connected to the EG vapour inlet (3) of the depolymerization vessel (1), and an outlet (23) for concentrated monomeric and oligomeric polyester residues. 33. The system (100) according to claim 31, wherein the liquid phase inlet (21) of the a EG recycling column (20) is connected to the solvent outlet (14) of the filter (12), or the solvent outlet (18) of the precipitation and separation vessel (16), or the solvent outlet (31) of the contaminant precipitation vessel (29).

Description

PROCESS FOR MIXED FABRIC REJUVINATION Field of the Invention This invention pertains in general to the field of recycling of mixed fiber fabrics. More specifically, the invention pertains to a method for mixed fabric fiber rejuvenation, wherein the mixed fabric fiber material comprises polyester and natural fiber material, and where the polyester is reacted with ethylene glycol EG. Further, the invention pertains to a system for such a mixed fabric fiber rejuvenation. Background of the Invention One of the main problems for recycling mixed fiber fabrics is the difficulty in separating and sorting the different types of fibers. Mixed fiber fabrics are often made up of a blend of different materials, such as cotton, polyester, nylon, and others. These fibers may have different properties and require different recycling processes. The challenge lies in effectively and efficiently separating these fibers to obtain high-quality recycled materials. The recycling process typically involves shredding the fabric into smaller pieces and then using mechanical or chemical methods to break down the fibers. However, when different fibers are mixed together, it becomes more challenging to achieve a uniform and consistent output. Another issue is the difference in melting points and chemical properties of various fibers. During the recycling process, the fibers may be subjected to high temperatures and chemical treatments, which can lead to variations in the quality and properties of the resulting recycled materials. Some fibers may melt or degrade faster than others, affecting the overall quality of the recycled materials. Moreover, the presence of contaminants, such as dyes, finishes, or other additives, in mixed fiber fabrics can further complicate the recycling process. These contaminants may interfere with the recycling process or affect the quality of the recycled materials. As for the quality of the recycled materials obtained from mixed fiber fabric recycling, it can vary. Achieving high-quality recycled materials from mixed fiber fabrics is more challenging compared to recycling single-fiber materials. The different fibers may have varying degrees of degradation, leading to differences in the strength, color, and other properties of the recycled materials. Therefore, recycled materials from mixed fiber fabric recycling may also have limited applications. For instance, they may be suitable for certain lower-grade products, such as insulation or non-woven materials, rather than higher-value applications like textile or apparel production. Efforts are being made to develop improved recycling technologies and processes to address these challenges. Innovations in fiber sorting, chemical treatments, and mechanical processes are being explored to enhance the quality and efficiency of recycling mixed fiber fabrics. This is especially important, since textile waste is a significant environmental issue. According to the Ellen MacArthur Foundation, the equivalent of one garbage truck full of textiles is landfilled or burned every second globally. This figure includes various types of textiles, including mixed fiber fabrics. The United Nations Environment Programme (UNEP) estimates that the global fashion industry produces approximately 92 million tons of textile waste annually. Since mixed fiber fabrics form a significant portion of textile waste streams, and are commonly found in clothing, home textiles, and other textile products, there is a great need for improved methods for achieve high-quality recycled materials from these complex mixed fabric textile waste streams. Summary of the Invention Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing a method for mixed fabric fiber rejuvenation, wherein the method comprises the steps of: - adding ethylene glycol (EG) in gas phase at a temperature of between 190° to 250° C trough vapour injection to a fabric fibre material comprising polyester and natural fibre material, whereby at least partly depolymerising the polyester material to monomeric and oligomeric polyester residues, the monomeric and oligomeric polyester residues being dissolved in condensed, excess of liquid EG; - optionally adding liquid phase EG, - recovering a solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG, and an essentially polyester-free natural fibre as a solid product; and - optionally separating the solvent phase, comprising the monomeric and oligomeric polyester residues and unreacted EG, from the solid product, comprising essentially polyester-free natural fibre. Further, is provided the method wherein the monomeric polyester residues are bis(hydroxy ethyl) terephthalate (BHET). Also, is provided the method wherein the natural fibre material comprises fib