EP-4737508-A1 - CHEMICAL RECYCLING METHOD FOR MIXED WASTE POLYMERS

EP4737508A1EP 4737508 A1EP4737508 A1EP 4737508A1EP-4737508-A1

Abstract

The present invention relates to a method for recycling mixed polymers comprising a polymer having an urethane functional group and/or a polymer having an amide functional group, in which, in recycling mixed polymers comprising a polymer having an urethane functional group and/or a polymer having an amide functional group, by sequentially or simultaneously bringing, into contact with the mixed polymers, a first compound including at least one aromatic compound having one or more alkoxy functional groups and a second compound including at least one compound having one or more alcohol functional groups, the polymer having an urethane functional group in a composite polymer is selectively dissolved, filtered, and separated, and thus the separated polymer having an urethane functional group can be separately depolymerized.

Inventors

CHO, Joung Mo
LE, Thi Hong Ngan

Assignees

Korea Research Institute of Chemical Technology

Dates

Publication Date: 20260506
Application Date: 20240730

Claims (16)

A composition for selectively dissolving and separating a polymer having a urethane functional group and/or a polymer having an amide functional group from a mixed polymer material, wherein the mixed polymer material is a material in which at least one polymer selected from a polymer having a urethane functional group and a polymer having an amide functional group and at least one polymer selected from cotton, linen, rayon, silk, acrylic, polyethylene, polypropylene, and a polymer having an ester functional group constitute a part or all of the components of the mixed polymer material, and wherein the composition comprises: at least one first compound selected from aromatic compounds having at least one alkoxy functional group; and at least one second compound selected from compounds having at least one alcohol functional group.
The composition of claim 1, wherein a weight ratio of the first compound to the second compound is in a range of 0.01 to 100.
A method for selectively dissolving and separating a polymer having a urethane functional group and/or a polymer having an amide functional group from a mixed polymer material, wherein the mixed polymer material is a material in which at least one polymer selected from a polymer having a urethane functional group and a polymer having an amide functional group and at least one polymer selected from cotton, linen, rayon, silk, acrylic, polyethylene, polypropylene, and a polymer having an ester functional group constitute a part or all of the components of the mixed polymer material, and wherein the polymer having the urethane functional group and/or the polymer having the amide functional group are selectively dissolved from the mixed polymer material by bringing, into sequential or simultaneous contact with the mixed polymer material, at least one first compound selected from aromatic compounds having at least one alkoxy functional group and at least one second compound selected from compounds having at least one alcohol functional group.
The method of claim 3, wherein when the polymer having the amide functional group is not present in the mixed polymer material, a temperature range for selectively dissolving only the polymer having the urethane functional group is from 100°C to 180°C.
The method of claim 3, wherein when both the polymer having the urethane functional group and the polymer having the amide functional group are present in the mixed polymer material, a temperature range for dissolving the polymer having the urethane functional group and the polymer having the amide functional group is from 135°C to 180°C.
The method of claim 3, wherein the sequential contact is performed by bringing the first compound into contact with the mixed polymer material first, followed by bringing the second compound into contact therewith.
The method of claim 3, wherein a mass ratio of the first compound to the mixed polymer material is in a range of 0.1 to 1,000 times, and a weight ratio of the first compound to the second compound is in a range of 0.01 to 100.
A method for recycling a mixed polymer material, wherein the mixed polymer material is a material in which at least one polymer selected from a polymer having a urethane functional group and a polymer having an amide functional group and at least one polymer selected from cotton, linen, rayon, silk, acrylic, polyethylene, polypropylene, and a polymer having an ester functional group constitute a part or all of the components of the mixed polymer material, the method comprising: (a) bringing, into contact with the mixed polymer material, at least one first compound selected from aromatic compounds having at least one alkoxy functional group and at least one second compound selected from compounds having at least one alcohol functional group, thereby selectively dissolving only the polymer having the urethane functional group and/or the polymer having the amide functional group within the mixed polymer material; (b) filtering the mixed solution generated after the selective dissolution to separate the polymer having the urethane functional group and/or the polymer having the amide functional group from the mixed polymer material; and (c) depolymerizing the polymers separated as a solid phase.
The method of claim 8, wherein the polymers depolymerized in step (c) include the polymer having the ester functional group.
The method of claim 9, further comprising: after step (c), (d) adjusting a temperature of the mixture containing the separated polymers having the urethane functional group and the amide functional group, thereby selectively precipitating only the polymer having the amide functional group and separating the polymer having the urethane functional group; and (e) depolymerizing the separated polymer having the urethane functional group.
The method of claim 9, further comprising: after step (c), depolymerizing the separated polymer having the urethane functional group.
The method of claim 10 or 11, wherein the depolymerizing of the polymer having the urethane functional group is performed by adding a depolymerization catalyst for the polymer having the urethane functional group to the filtrate obtained after filtration.
The method of claim 12, wherein the depolymerization catalyst for the polymer having the urethane functional group is at least one selected from the group consisting of metal catalysts such as alkali hydroxides, alkaline earth hydroxides, alkali acetates, alkaline earth acetates, alkali carbonates, alkali bicarbonates, alkaline earth carbonates, alkali oxides; and guanidine-based or amine-based organic compounds.
The method of claim 11, wherein the depolymerizing of the polymer having the urethane functional group is performed at a temperature in a range of 100°C to 170°C.
The method of claim 9, wherein the depolymerizing of the polymer having the ester functional group in step (c) is performed by using at least one method selected from hydrolysis, glycolysis, methanolysis, ethanolysis, and ammonolysis.
The method of claim 8, wherein among the solid-phase polymers separated in step (c), non-depolymerizable materials are separated from the reaction product by filtration or centrifugation.

Description

Technical Field The present disclosure relates to a method for chemically recycling mixed polymer materials, in which, in recycling a mixed polymer material composed of polymer compounds having dissimilar chemical structures, which are randomly mixed or are integrated to have a predetermined composition and specific structure, a series of processes is configured by establishing a plurality of conditions under which only a specific polymer can be selectively dissolved from the mixed polymer material, thereby enabling partial or specific polymers to be physically separated individually, followed by depolymerization of the separated polymers. Background Art Polymers synthesized from petroleum-derived feedstocks offer advantages such as being inexpensive, durable, and easy to mold and process. Accordingly, they have been widely used in the production of various products such as synthetic fibers and plastics. Due to these advantages, the consumption of products manufactured from such synthetic polymers has increased dramatically across many aspects of modern daily life over the past several decades. However, synthetic polymer waste that is not properly managed after use is often treated by environmentally unfriendly methods, giving rise to various environmental problems. In some cases, such waste is disposed of in landfills or released into the environment, where it undergoes fragmentation into smaller pieces. These microplastic particles subsequently disperse throughout ecosystems, accumulate in living organisms, and can ultimately be reabsorbed into the human body through pathways such as fine particulate matter, drinking water, and food. This widespread contamination poses direct threats to human health and the living environment. To address these issues, extensive research and development efforts have been undertaken to minimize the accumulation of plastics or to mitigate their environmental impact. Such efforts include the development of novel plastic materials with short degradation cycles under natural conditions, as well as approaches ranging from chemical depolymerization of conventional petroleum-based plastics to physical recycling and reprocessing of plastic waste. However, material or physical recycling methods, in which polymeric materials are reused after washing or reused with partial modification of their shape or properties, are known to suffer from difficulties in controlling material properties and quality. As a result, their applications and the number of feasible recycling cycles are limited. On the contrary, depolymerization methods that chemically break down post-consumer synthetic polymer products enable the production of monomers corresponding to the original feedstocks prior to polymer synthesis. Even after repeated recycling cycles, such methods allow for reproduction of products with quality equivalent or similar to that of the virgin material. Therefore, chemical depolymerization has attracted considerable attention as a practical technology for establishing a circular resource economy. Since polymers exhibit different degradation behaviors depending on their types, and the nature and properties of degradation products also vary, the recycling of mixed polymer products containing two or more types of polymers generally necessitates a preliminary classification process to separate the materials into single substances having uniform polymer structures. In particular, post-consumer textile waste is frequently a complex mixture of various fiber types and is commonly disposed of as blended materials. Thus, recycling such textile waste requires a series of processes, including pretreatment steps such as sorting and separation of individual polymers and removal of foreign materials, as well as effective methods for decomposing or processing the separated materials at each stage. With the recent development of functional fiber materials, the related textile market has continued to expand significantly. In particular, the market for polyurethane-based fibers, commonly referred to as Spandex, Elastan, or Lycra, has experienced explosive growth. Depending on the manufacturer, such polyurethane fibers are marketed under various trade names, including Elaspan, Acepora, Creora, INVIYA, ROICA, and Dorlastan. Polyurethane-based fibers exhibit excellent elasticity as well as outstanding biocompatibility, enabling them to completely replace conventional rubber materials. To further enhance functionality, fibers produced by blending polyurethane with other synthetic fibers are far more extensively used than homogeneous fibers. In addition to fibers containing polyurethane, fibers composed of various combined materials may also be utilized to improve functionality or durability. For example, mixed fibers may be produced from combinations of synthetic polymer materials such as polyester or nylon, or natural polymer materials derived from plant- or animal-based sources, such as cotton, cellulose, flax, a