Method for separating specific fibers from blended fibers

Abstract

One embodiment of the present invention relates to a method for separating cellulose fibers from raw material fibers containing cellulose-based fibers and, more specifically, provides: a method in which a quaternary ammonium alcohol compound and an organic acid are mixed to prepare a deep eutectic solvent (DES) and cellulose fibers can be selectively separated from raw material fibers by using the prepared DES; and a device for separating out and recovering cellulose fibers. One embodiment of the present invention relates to a method for separating out polyurethane-based fibers and, more specifically, provides a method for separating out polyurethane-based fibers, an extraction solution composition for separation, and a separation device, the method comprising using a heterocyclic solvent and benzyl alcohol so as to selectively dissolve polyurethane-based fibers of blended fabrics, which are composed of the polyester-based fibers and polyurethane-based fibers, thereby enabling same to be separated from the blended fabrics.

Description

Method for separating specific fibers from blended fibers

[0001] The present invention relates to a method for separating specific fibers from blended fibers, and as a first embodiment, the present invention relates to a method for separating cellulose fibers from raw fibers containing cellulose-based fibers, and more specifically, to a method for producing DES (Deep Eutectic Solvents) by mixing a quaternary ammonium alcohol compound with an organic acid, and to selectively separating cellulose fibers from raw fibers using the produced DES, and to an apparatus for separating and recovering cellulose fibers.

[0002] In a second embodiment, the present invention relates to a method for separating polyurethane fibers, and more specifically, to a method for separating polyurethane fibers from a blended fabric composed of polyester fibers and polyurethane fibers by using a heterocyclic solvent and benzyl alcohol to selectively dissolve the polyurethane fibers, thereby separating them from the blended fabric, an extraction solution composition for separation, and a separation apparatus.

[0003] Blended fibers, widely used in the textile industry, are manufactured by combining various polymer materials and primarily consist of a mixture of polyester and cellulose-based fibers (such as cotton, viscose, and Lyocell). While these blended fibers can improve properties such as physical strength, comfort, and moisture absorption by combining the advantages of each material, they present a problem in that recycling is limited due to the difficulty of separating the materials when they are disposed of as waste.

[0004] Previous studies on the separation and removal of cellulose-based fibers and polyesters have primarily relied on methods utilizing strong acids (such as hydrochloric acid, sulfuric acid, and nitric acid) or special solvents like ionic liquids (such as NMMO). While methods using strong acids offer the advantage of effectively degrading cellulose-based fibers, they face limitations that make commercialization difficult due to reduced equipment durability caused by the corrosiveness of the acids, safety concerns in the working environment, and the environmental burden resulting from the acid treatment. The use of ionic liquids has garnered attention for its potential to increase recycling efficiency and reduce environmental side effects; however, these solvents are subject to constraints, such as very high manufacturing costs and difficulties in large-scale commercial use. In particular, the recovery and recycling processes for these solvents require additional costs, acting as factors that hinder economic feasibility and practicality.

[0005] Recently, Deep Eutectic Solvents (DES) have garnered attention as an eco-friendly and cost-effective alternative. DES possesses advantages such as being non-toxic, low-flammability, biodegradable, and capable of being manufactured using inexpensive raw materials. Furthermore, due to their low vapor pressure, they enhance safety in the workplace, and their ease of solvent recovery and reuse makes them recognized as a sustainable technology. However, research on separation and recycling technologies for blended fibers using DES remains in its early stages, and verification of the efficiency of various DES combinations is particularly necessary.

[0006] This invention aims to develop a technology for the environmentally friendly processing of blended fibers composed of polyester and cellulose-based fibers. It proposes a technology that effectively separates and recycles blended fibers by using DES to selectively separate the cellulose-based fibers while leaving the polyester behind. Through this, the limitations of existing technologies using strong acids or ionic liquids are overcome, and both economic efficiency and environmental friendliness can be simultaneously satisfied.

[0007]

[0008] Blended fabrics are widely used in the textile industry across various applications, including clothing, industrial textiles, sportswear, and medical textiles. Blended fabrics are produced by combining two or more different fibers to provide superior physical properties, durability, elasticity, breathability, and comfort compared to using specific fibers individually. A representative example of a blended fabric is one composed of polyester and polyurethane, which is extensively utilized in sportswear, functional clothing, and medical materials. However, because blended fabrics have a structure in which various types of fibers are complexly bonded, the purity of individual fibers is reduced, leading to difficulties in the separation and purification processes during recycling. In particular, when applying chemical recycling that utilizes discarded fabrics as raw materials, a process of extracting raw materials through the selective decomposition or dissolution of specific fibers is required; however, effectively separating desired fibers from a mixed state is not easy. Therefore, it is essential to develop technologies that can selectively remove specific fibers from blended fabrics and recycle the remaining fibers into high-quality raw materials.

[0009] Research has been ongoing to effectively separate polyurethane fibers (e.g., Spandex) from blended fabrics, and existing studies have primarily utilized methods that selectively dissolve polyurethane using polar organic solvents. Solvents widely used to date include N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP). While these solvents are characterized by their high solubility in dissolving polyurethane, they are highly toxic and harmful to humans and the environment; long-term exposure can lead to absorption through the skin and respiratory system, potentially causing damage to the liver and kidneys. Furthermore, the use of DMF and NMP is strictly restricted under the European Union (EU) REACH regulations, creating a need for the development of eco-friendly solvents to replace them. Since specific solvents can only be used with authorization or at concentrations below limited levels under REACH regulations, their applicability in industrial settings is declining. Additionally, the high purification and disposal costs associated with the treatment of waste solvents are creating a significant economic burden.

[0010] Accordingly, the present invention investigated a technology capable of removing polyurethane fibers in an environmentally friendly manner compared to existing polar organic solvents (DMF, NMP). As a result of testing various solvents, it was confirmed that heterocyclic solvents such as γ-Butyrolactone, ε-Caprolactone, and ε-Caprolactam, as well as Benzyl alcohol, exhibited superior performance compared to existing solvents. The solvents used in the present invention are not subject to REACH regulations, possess excellent safety due to low human toxicity, and reduce the burden of environmental pollution by exhibiting superior biodegradability compared to existing polar organic solvents. Furthermore, experimental results confirmed excellent polyurethane solubility, which is expected to allow for the replacement of toxic solvents used in existing processes. By utilizing the solvent conditions of the present invention, polyester fibers and polyurethane fibers can be selectively separated and utilized as recycled raw materials. In addition, using eco-friendly solvents reduces waste solvent disposal costs and protects workers' health, thereby improving safety at industrial sites.

[0011] The present invention has been devised to solve the aforementioned problems, and one embodiment of the present invention provides a method for separating cellulose fibers.

[0012] In addition, another embodiment of the present invention provides an apparatus for separating and recovering cellulose fibers from raw fibers.

[0013] In addition, another embodiment of the present invention provides a method for separating polyurethane fibers.

[0014] In addition, another embodiment of the present invention provides an extraction solution composition for separating polyurethane fibers from raw fibers.

[0015] In addition, another embodiment of the present invention provides a device for separating polyurethane fibers from raw fibers.

[0016] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0017] As a technical means for achieving the aforementioned technical problem, one aspect of the first embodiment of the present invention is,

[0018] A method for separating cellulose fibers is provided, comprising the steps of: mixing a quaternary ammonium alcohol compound and an organic acid to form a co-solvent; immersing a raw fiber containing at least a cellulose component in the co-solvent; reacting the raw fiber with the co-solvent to selectively separate the cellulose fiber; and recovering the separated cellulose fiber; wherein the co-solvent is characterized by mixing the quaternary ammonium alcohol compound and the organic acid in a ratio of 1 to 3 to 3 to 1.

[0019] The step of forming the above co-solvent; can be formed by adding water to dissolve the quaternary ammonium alcohol compound and the organic acid, and then removing the water by vacuum distillation.

[0020] The step of forming the above co-solvent; can be performed by raising the temperature of the quaternary ammonium alcohol compound and the organic acid to a predetermined temperature and mixing them for a predetermined time to form the co-solvent.

[0021] The above-mentioned predetermined temperature may be a temperature in the range of 60 to 100℃.

[0022] The above predetermined time may be a time in the range of 1 to 3 hours.

[0023] The above co-solvent may be a mixture of a quaternary ammonium alcohol compound and an organic acid in a ratio of more than 1 and less than or equal to 3:1.

[0024] The step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent can be performed for 0.5 to 3 hours.

[0025] The step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent can be performed at a temperature greater than 110°C and less than 150°C.

[0026] In the step of selectively separating cellulose fibers by reacting the raw fiber with the co-solvent; the co-solvent may be added in a bath ratio of 10 to 100 parts by weight per 1 part by weight of the raw fiber.

[0027] The above cellulose fibers may be selected from the group consisting of pulp fibers, purified cellulose, and pulp boards.

[0028] The above raw fibers include cellulose fibers and synthetic fibers, and some fibers can be preserved without being damaged by the co-solvent.

[0029] The method may further include a step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent; and a step of recovering the used co-solvent thereafter.

[0030] The above quaternary ammonium alcohol compound may be choline chloride, choline iodide, choline hydroxide, or choline bitartrate.

[0031] The above organic acid may be an organic acid having n carboxyl groups, and n may be an integer from 1 to 5.

[0032] The above organic acid may be citric acid.

[0033]

[0034] Another aspect of the first embodiment of the present invention is,

[0035] The present invention provides an apparatus for separating and recovering cellulose fibers from raw fibers, comprising: a co-solvent forming unit that mixes the quaternary ammonium alcohol compound and the organic acid, each having a nozzle for introducing a quaternary ammonium alcohol compound and an organic acid; a reaction unit that extends and is connected from the outlet nozzle of the co-solvent forming unit and is equipped with a co-solvent injection nozzle to supply the formed co-solvent and a raw fiber input port for introducing the raw fiber, wherein a reaction between the raw fiber and the co-solvent takes place inside; and a cellulose recovery unit that extends and is connected from the outlet of the reaction unit and is connected to transfer the separated cellulose to perform solid-liquid separation, wherein the co-solvent is characterized in that the quaternary ammonium alcohol compound and the organic acid are mixed in a ratio of 1 to 3:3 to 1.

[0036]

[0037] One aspect of the second embodiment of the present invention is,

[0038] A method for separating polyurethane fibers from raw fibers is provided, comprising the steps of: preparing an extraction solvent; immersing raw fibers containing at least polyurethane fibers and polyester fibers in the extraction solvent; contacting the raw fibers with the extraction solvent to selectively dissolve the polyurethane fibers; and filtering the solution in which the polyurethane fibers are dissolved to recover the separated polyurethane fibers.

[0039] The step of selectively dissolving the polyurethane-based fiber by contacting the above raw fiber with an extraction solvent can be performed at a temperature of 80°C to 140°C.

[0040] The method may further include a step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent; and a step of further dissolving polyester fibers by raising the temperature to 145°C to 200°C.

[0041] The above extraction solvent may include substituted or unsubstituted pentagonal or heptagonal cyclic esters, or alcohol compounds containing aromatic groups.

[0042] The above extraction solvent may include γ-butyrolactone, ε-caprolactone, or benzyl alcohol.

[0043] The method may further include a step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent; and a step of promoting the selective separation of polyurethane-based fibers by raising the temperature to 145°C to 200°C.

[0044] The above extraction solvent may include substituted or unsubstituted pentagonal or heptagonal cyclic amide compounds.

[0045] The above extraction solvent may include ε-caprolactam or γ-butyrolactam.

[0046] The step of selectively dissolving the polyurethane-based fiber by contacting the above raw fiber with an extraction solvent can be performed for 0.1 to 4 hours.

[0047] In the step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with the extraction solvent; the extraction solvent may be added in a bath ratio of 5 to 150 parts by weight per 1 part by weight of the raw fibers.

[0048] The method may further include a step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent; and a step of recovering the used extraction solvent by distillation.

[0049]

[0050] Another aspect of the second embodiment of the present invention is,

[0051] The present invention provides an extraction solution composition for separating polyurethane fibers from raw fibers, comprising: raw fibers containing at least polyurethane fibers and polyester fibers; and an extraction solvent; wherein the extraction solvent comprises a substituted or unsubstituted pentagonal or heptagonal cyclic ester or an alcohol compound containing an aromatic group.

[0052] The polyurethane fiber may be in a melted state at a temperature of 80°C to 140°C.

[0053] At a temperature of 145°C to 200°C, both the polyester fibers and the polyurethane fibers may be in a melted state.

[0054]

[0055] Another aspect of the second embodiment of the present invention is,

[0056] The present invention provides an extraction solution composition for separating polyurethane fibers from raw fibers, comprising: raw fibers containing at least polyurethane fibers and polyester fibers; and an extraction solvent; wherein the extraction solvent comprises a substituted or unsubstituted pentagonal or heptagonal cyclic amide compound.

[0057] The polyurethane fiber may be in a melted state at a temperature of 80°C to 140°C.

[0058] Insolation of polyester fibers and dissolution of polyurethane fibers may occur at temperatures of 145°C to 200°C.

[0059]

[0060] Another aspect of the second embodiment of the present invention is,

[0061] The present invention provides a device for separating polyurethane fibers from raw fibers, comprising: an extraction solvent storage unit for storing an extraction solvent; a reaction unit extending from and connected to an outlet nozzle of the extraction solvent storage unit, and equipped with an extraction solvent injection nozzle to supply the formed extraction solvent and a raw fiber input port for introducing the raw fiber, wherein a reaction between the raw fiber and the extraction solvent takes place inside; and a polyurethane fiber separation unit extending from and connected to an outlet of the reaction unit, wherein the separated polyurethane fiber or polyester fiber is conveyed and solid-liquid separation is performed.

[0062] According to one embodiment of the first aspect of the present invention, Deep Eutectic Solvents (DES) are non-toxic, have low flammability, are biodegradable, and can be manufactured using inexpensive raw materials. Furthermore, due to their low vapor pressure, they enhance safety in the working environment, and because the recovery and reuse of the solvent are easy, they are a sustainable technology that is superior in terms of cost, environment, and safety compared to methods using strong acids and ionic liquids.

[0063] In addition, according to one embodiment of the present invention, raw fibers can be effectively separated and recycled by using DES to selectively separate cellulose-based fibers while leaving polyester behind.

[0064]

[0065] According to one embodiment of the second aspect of the present invention, solvents of the benzyl alcohol, lactam, and lactone series, unlike the widely used DMF and MEK, are not regulated as toxic substances or accident prevention substances and can be used without environmental and legal restrictions. This can contribute to protecting the health of workers and implementing safer recycling processes in industrial sites.

[0066] In addition, according to one embodiment of the present invention, the solvent of the present invention has a selective dissolution effect similar to that of cyclic ethers (e.g., THF) known to dissolve polyurethane, while having excellent safety due to its high boiling point and flash point. Although cyclic ethers pose a risk of fire and explosion during handling due to their low boiling point and flash point, the solvent of the present invention has a low risk of such danger, making it highly industrially useful and capable of significantly improving safety in the working environment.

[0067] Furthermore, according to one embodiment of the present invention, the solvent of the present invention can be effectively used as a single solvent, and also has high compatibility with various solvents, allowing it to be utilized as a mixed solvent. This enables the optimization of the solvent composition according to process conditions, and further improves dissolution performance when a specific mixed solvent system is applied. Additionally, since phase separation does not occur at the process temperature, there is no need for additional stirring or the consumption of separate energy, thereby increasing process efficiency and reducing operating costs.

[0068] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims.

[0069] FIG. 1 shows the recovered cellulose fibers of Comparative Examples 1-1 to 1-3 and Example 1-1 according to one embodiment of the present invention.

[0070] FIG. 2 shows a glass container containing pure cotton and a DES solution after reaction is completed, according to one embodiment of the present invention, Comparative Examples 2-1 to 2-5 and Examples 2-1 and 2-2.

[0071] FIG. 3 shows the recovered cellulose fibers of Comparative Examples 3-2 to 3-6 and Example 3-1 according to one embodiment of the present invention.

[0072] FIG. 4 shows the recovered cellulose fibers of Examples 4-1 to 4-7 according to one embodiment of the present invention.

[0073] Hereinafter, an embodiment corresponding to the first embodiment of the present invention will be described in detail so that a person skilled in the art to which the present invention pertains can easily implement it. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0074] Preparation Example: Separation of cellulose fibers according to the conditions of organic acids included in the cosolvent

[0075] Deep Eutectic Solvents (DES) were formed by stirring choline chloride (ChCl) and an organic acid, and 100% cotton yarn was added to the DES and stirred to react. Once dissolution was complete, water was added to precipitate the cellulose fibers, and the DES was recovered by filtration. The filtered cellulose fibers were then dried overnight in an oven at 100°C. Experiments were conducted using choline chloride (ChCl) and an organic acid according to the conditions listed in Table 1 below. As a result, yellowing occurred in Preparation Example 2, and the size of the obtained solids was inconsistent in Preparation Examples 3 and 4. Among Preparation Examples 1, 5, and 6, which yielded white powder as a product, the citric acid monohydrate of Preparation Example 5 is considered suitable as it has the greatest strengths in terms of eco-friendliness and economics.

[0076] Classification Raw Material Fiber Type Fiber Weight DES (Molar Ratio) DES Reaction Result Temperature Time Temperature Time Preparation Example 1 Room 0.10 g ChCl 5 g : Formic acid 2.7 mL (1:2) 60℃ 1 h 130℃ 2 h White powder Preparation Example 2 Room 0.09 g ChCl 10 g : Citric acid anhydrous 7 g (2:1) 110℃ 4 h 130℃ 3 h Beige powder Preparation Example 3 Room 0.10 g ChCl 5 g : Oxalic acid 3.2 g (1:1) 80℃ 1 h 130℃ 3 h Irregular yellow powder Preparation Example 4 Room 0.10 g ChCl 5 g : Succinic acid 4.2 g (1:1) 100℃ 3 h 130℃ 3 h Irregular white powder Preparation Example 5 Room 0.09 g ChCl 10 g : Citric acid monohydrate 7 g (2:1) 80℃ 2 h 130℃ Overnight white powder Preparation Example 6 0.11 g ChCl 5 g : Lactic acid 27 mL (1:10) 85℃ 2 h 110℃ Overnight white powder

[0077] Experimental Example 1: Determination of the molar ratio of choline chloride and citric acid as co-solvents

[0078] Example 1-1: Setting a 2:1 molar ratio of choline chloride and citric acid

[0079] A mixture of choline chloride (ChCl, 10 g, 71.6 mmol) and citric acid (Citric acid monohydrate, CAmh, 7 g, 35.8 mmol) is stirred at 180 rpm at 80 ℃ for 1 hour and 30 minutes to form DES (Deep Eutectic Solvents). Pure cotton (Cotton 100%) containing a cellulose component is added to the DES and stirred at 300 rpm at 130 ℃ for 1 hour. Once decomposition is complete, water is added to precipitate the cellulose fibers and filter to recover the DES, and the filtered cellulose fibers are dried overnight in a 100 ℃ oven.

[0080] Comparative Examples 1-1 to 1-3: Change in the molar ratio of choline chloride and citric acid

[0081] The same operation as in Example 1-1 was performed except that the molar ratio of choline chloride and citric acid, the weight of the raw fiber, and the time for forming the cosolvent were changed as shown in Table 2 below, the results are shown in Table 2 below, and the recovered cellulose fiber is shown in Figure 1.

[0082] Classification Raw Material Fiber ChCl:CA mh (Molar Ratio) DES Reaction Recovered Cellulose Fiber Temperature Time RPM Temperature Time RPM Comparative Example 1 - 10.09 g 15 g : 7 g (3:1) 80℃ 5 h 180 130℃ 1 h 300 0.08 g Example 1 - 10.10 g 10 g : 7 g (2:1) 80℃ 1.5 h 180 130℃ 1 h 300 0.09 g Comparative Example 1 - 20.10 g 5 g : 7 g (1:1) 80℃ 40 min 180 130℃ 1 h 300 0.07 g Comparative Example 1 - 30.10 g 5 g : 14 g (1:2) 80℃ 40 min 180 130℃ 1 h 300 0.07 g

[0083]

[0084] In Example 1-1 and Comparative Examples 1-1 to 1-3, pure cotton was degraded by the formed DES; however, in the case of Comparative Example 1-1, the time for synthesizing DES was long, and as the citric acid ratio increased as in Comparative Examples 1-2 and 1-3, the time for synthesizing DES decreased. However, according to FIG. 1, the degree of yellowing varied depending on the molar ratio of choline chloride and citric acid, and as the citric acid ratio increased as in Comparative Examples 1-2 and 1-3, the degree of yellowing became more severe. When the molar ratio of choline chloride and citric acid was set to 2:1 as in Example 1-1, fibers with a relatively low degree of yellowing could be obtained at a relatively appropriate DES synthesis time, and the optimal molar ratio is determined to be 2:1.

[0085] Experimental Example 2: Setting the reaction temperature of the co-solvent and the raw fiber

[0086] Example 2-1: Setting reaction temperature to 120 ℃

[0087] Choline chloride (ChCl, 10 g, 71.6 mmol) and citric acid (Citric acid monohydrate, CAmh, 7 g, 35.8 mmol) are dissolved in water, and then water is removed by vacuum distillation using a rotary evaporator to produce DES. Pure cotton (Cotton 100%) containing cellulose components is added to the DES and stirred at 300 rpm at 120 ℃ for 1 hour and 30 minutes. Once the decomposition of the pure cotton is complete, water is added to precipitate and filter the cellulose fibers to recover the DES, and the filtered cellulose fibers are dried overnight in an oven at 100 ℃.

[0088] Example 2-2: Setting reaction temperature to 130 ℃

[0089] The same operation as in Example 2-1 was performed, except that pure cotton (Cotton 100%) containing a cellulose component was added to DES and stirred at 300 rpm for 1 hour and 30 minutes at 130 ℃.

[0090] Comparative Examples 2-1 to 2-5: Change in reaction temperature

[0091] Except for changing the reaction temperature and reaction time as shown in Table 3 below, the same operation as in Example 2-1 was performed, the results are shown in Table 3 below, and a glass container containing pure cotton and the DES solution after the reaction was completed is shown in FIG. 2.

[0092] Classification Raw Material Fiber ChCl:CAmh (Molar Ratio) Reaction Recovered Cellulose Fiber Temperature Time RPM Comparative Example 2 - 10.10 g 10 g : 7 g (2:1) 80℃ 1 h 300 - Comparative Example 2 - 20.10 g 10 g : 7 g (2:1) 90℃ 1 h 300 - Comparative Example 2 - 30.10 g 10 g : 7 g (2:1) 100℃ 1 h 300 - Comparative Example 2 - 40.10 g 10 g : 7 g (2:1) 110℃ 1 h 300 - Example 2 - 10.10 g 10 g : 7 g (2:1) 120℃ 1.5 h 3000 0.09 g Example 2 - 20.10 g 10 g : 7 g (2:1) 130℃ 1.5 h 3000 0.09 g Comparative Example 2-50.10 g10 g : 7 g (2:1)150℃1 h3000.09 g

[0093] In Comparative Example 2-1, the pure cotton hardly decomposed, while in Comparative Examples 2-2 and 2-3, the pure cotton expanded. In Comparative Example 2-4, the pure cotton decomposed slightly, allowing the decomposed fibers to be identified. In Examples 2-1, 2-2, and Comparative Example 2-5, the pure cotton was completely decomposed; however, in the case of Comparative Example 2-5, the color of the reaction solution was a deep yellow, unlike the other examples. In the case of Example 2-1, it was confirmed that the pure cotton was not completely dissolved after a reaction time of 1 hour. The dissolution rate varies depending on the temperature, and the degree of decomposition of the pure cotton according to the reaction temperature could be determined through Figure 2. As seen in Examples 2-1 and 2-2, when the reaction temperature was set to 120 and 130 ℃, the pure cotton was completely decomposed and the degree of yellowing was not severe, indicating that these are the most appropriate temperatures.

[0094] Experimental Example 3: Setting the reaction time between the co-solvent and the raw fiber

[0095] For Example 3-1 and Comparative Examples 3-1 to 3-6, the same operation as in Example 2-1 was performed except that the reaction time and reaction temperature were changed as shown in Table 4 below, the results are shown in Table 4 below, and the recovered cellulose fibers are shown in FIG. 3.

[0096] Classification Raw Material Fiber ChCl:CAmh (Molar Ratio) Reaction Recovered Cellulose Fiber Temperature Time RPM Comparative Example 3 - 10.10 g 10 g : 7 g (2:1) 120℃ 1 h 300 Comparative Example 3 - 20.10 g 10 g : 7 g (2:1) 120℃ 2 h 300 0.08 g Example 3 - 10.10 g 10 g : 7 g (2:1) 130℃ 1 h 300 0.09 g Comparative Example 3 - 30.10 g 10 g : 7 g (2:1) 130℃ 2 h 300 0.08 g Comparative Example 3 - 40.10 g 10 g : 7 g (2:1) 130℃ 4 h 300 0.08 g Comparative Example 3 - 50.10 g 10 g : 7 g (2:1) 130℃ 6 h 3000.09 g Comparative Example 3-60.10 g 10 g : 7 g (2:1) 130℃ Overnight 3000.08 g

[0097] Comparative Example 3-1 had expanded pure cotton remaining, and according to FIG. 3, it was confirmed that in Example 3-1 and Comparative Examples 3-3 to 3-6, as the reaction time increased, the fiber particle size decreased and the degree of yellowing increased. As in Example 3-1, when reacted at a reaction temperature of 130°C for 1 hour, the particle size was not too small and almost no yellowing occurred, so the optimal reaction time was determined to be 1 hour.

[0098] Experimental Example 4: Setting the Bath Ratio of Raw Fiber and Co-solvent

[0099] After dissolving choline chloride (ChCl, 2 eq) and citric acid (Citric acid monohydrate, CAmh, 1 eq) in water, water is removed by vacuum distillation using a rotary evaporator to produce DES. Pure cotton (Cotton 100%) containing cellulose components is added to the DES in ratios of 1:10, 1:20, 1:40, 1:60, 1:80, and 1:100, and the mixture is stirred with the reaction temperature, reaction time, and rpm set as shown in Table 5. Once dissolution is complete, water is added to precipitate cellulose fibers and filter to recover the DES. The filtered cellulose fibers are then dried overnight in a 100°C oven. The results are shown in Table 5 below, and the recovered cellulose fibers are shown in Figure 4.

[0100] Classification Raw Material Fiber: DES (Bath Ratio) Raw Material Fiber DES Reaction Recovered Cellulose Fiber Other Temperature Time RPM Example 4-11: 100.60 g 6 g 130℃ 4 h 3000 0.51 g (85%) vial (closed system) Example 4-21: 200.30 g 6 g 130℃ 3.5 h 3000 0.24 g (80%) vial (closed system) Example 4-31: 400.15 g 6 g 130℃ 3 h 3000 0.12 g (80%) vial (closed system) Example 4-41: 600.10 g 6 g 130℃ 1.5 h 3000 0.08 g (80%) vial (closed system) Example 4-51: 800.10 g 8 g 130℃ 1 h 3000 0.08 g (80%) vial (closed system) Example 4-61: 1000.10 g 10 g 130℃ 0.5 h 3000.08 g (80%) vial (closed system) Example 4-71: 1000.10 g 10 g 130℃ 1 h 3000.09 g (90%) RBF + reflux condenser (open system)

[0101] In Example 4-1, where the bath ratio was set to 1:10, pure cotton was dissolved, and in Example 4-7, where the bath ratio was set to 1:100, 90% of cellulose fibers were recovered; however, it was confirmed that finer particles could be obtained in a closed system than in an open system, and the reaction time was shorter. In Examples 4-4 to 4-7, the amount of recovered cellulose fibers was maintained even when the amount of co-solvent was increased; therefore, it is determined that it is desirable to set the amount of co-solvent to 10 to 60 parts by weight per 1 part by weight of raw fiber.

[0102] Experimental Example 5: Separation of Cellulose Fibers from Cotton / Polyester Blended Fibers

[0103] For Experiments 1 to 4, choline chloride (ChCl, 2 eq) and citric acid (Citric acid monohydrate, CAmh, 1 eq) are dissolved in water, and then water is removed by vacuum distillation using a rotary evaporator to prepare DES. Raw fibers mixed with cotton and polyester are added to the DES in a ratio of 1:10 to 1:20 and stirred at 300 rpm at 130 ℃ for 1 hour. Once the decomposition of the raw fibers is complete, water is added to precipitate cellulose fibers, and the fibers are separated through two filters. The two filters are spaced vertically apart, with the lower layer being a cellulose filter and the upper layer being a sieve having a pore size of 355 to 900 μm. Cellulose fibers can be obtained from the cellulose filter, and polyester fibers can be obtained from the sieve. Cotton and Polyester filtered through each filter are dried overnight in a 100°C oven to recover the Cotton and Polyester.

[0104] Experiments were conducted by setting the raw fiber conditions as shown in Table 6 below. In Experiments 1 and 2, the individual fibers could be effectively separated from blended fibers with a cotton-to-polyester mixing ratio of 60:40 and 40:60. In Experiment 3, the raw fibers used in Experiment 1 were ground before the experiment was conducted, and results similar to those of Experiment 1 were obtained. This confirmed that the form of the raw material had almost no effect on the experiment. Experiment 4 was conducted to determine the effect of water on the experiment, and it was confirmed that the reactivity was significantly lower compared to Experiment 1. Therefore, it was found that controlling the water content plays a major role in the reaction.

[0105] Classification Raw Material Fiber DES (2:1 Molar Ratio) Raw Material Fiber Type Mixing Ratio Recovered Cotton Recovered PET Cotton PET Experiment 10.33 g 6.63 g Fabric 60 400 0.14 g 0.15 g Experiment 20.45 g 4.50 g Fabric 40 600 0.12 g 0.28 g Experiment 30.41 g 8.17 g Crushed 60 400 0.21 g 0.20 g Experiment 40.30 g 5.98 g (+Water 1g) Fabric 60 400 0.01 g 0.27 g

[0106]

[0107] Hereinafter, an embodiment corresponding to a second embodiment of the present invention will be described in detail so that a person skilled in the art to which the present invention pertains can easily implement it. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0108] Experimental Example 6: Separation of polyester fibers and polyurethane fibers from a blended fabric using a cyclic ester solvent

[0109] Example 5-1: Use of γ-Butyrolactone in a blended fabric of polyester and spandex (bath ratio 100)

[0110] A flask containing a magnetic bar for stirring and 30 mL of γ-Butyrolactone was placed in an oil bath at 180°C and stirred at 250 rpm to raise the temperature of the solvent. 0.3 g of a blended fabric consisting of 50% polyester and 50% spandex was added and stirred; 5 minutes after addition, all the spandex dissolved, and 11 minutes after addition, all the polyester fabric dissolved. The mixture was filtered using filter paper at 80°C to separate the filtrate and filtrate; the filtrate was then washed with water and ethanol and dried, resulting in 0.14 g of white granular polyester fabric. The filtrate containing dissolved spandex was cooled to a low temperature (room temperature) to precipitate the spandex; after filtration, it was washed and dried to obtain 0.08 g of ivory-colored spandex lumps.

[0111] Example 5-2: Use of γ-Butyrolactone in a blended fabric of polyester and spandex (bath ratio 20)

[0112] A flask containing a magnetic bar for stirring and 40 mL of γ-Butyrolactone was placed in an oil bath at 180°C and stirred at 250 rpm to raise the temperature of the solvent. 2.00 g of a blended fabric consisting of 50% polyester and 50% spandex was added and stirred for 1 hour, during which both the spandex and polyester fabrics dissolved. The mixture was filtered using filter paper at 80°C to separate the filtrate and filtrate; the filtrate was then washed with water and ethanol and dried, resulting in 0.95 g of white granular polyester fabric. The filtrate containing dissolved spandex was cooled to a low temperature (room temperature) to precipitate the spandex; after filtration, it was washed and dried to obtain 0.90 g of ivory-colored spandex lumps.

[0113] Comparative Example 5-1: Use of γ-Butyrolactone in Spandex Yarn

[0114] 15 mL of γ-Butyrolactone was added to 0.15 g of spandex yarn, and the temperature was increased from 60°C to 140°C by 20°C every hour. The yarn showed no change between 60 and 100°C, and swelled slightly when stirred at 120°C for 1 hour. After stirring at 140°C for 1 hour, it was confirmed that all the spandex had dissolved, and the mixture was cooled to a low temperature (room temperature) to obtain 0.10 g of white granular spandex.

[0115] Comparative Example 5-2: Use of γ-Butyrolactone in Polyester Fabric

[0116] 15 mL of γ-Butyrolactone was added to 0.15 g of polyester fabric, and the temperature was increased from 100°C to 180°C by 20°C every hour. When stirred for 1 hour at 140°C and 160°C, there was no change in the fabric, and when stirred for 10 minutes at 180°C, it was confirmed that the polyester fabric was completely dissolved. After cooling to a low temperature (room temperature), 0.14 g of white granular polyester was obtained.

[0117] Through this, it was found that when γ-Butyrolactone is used as a solvent, polyester does not dissolve under conditions where spandex dissolves (140°C, 1 hour), and when the bath ratio is reduced from 100 to 20, the yield of polyester is similar, but the yield of spandex increases by about 40%, and it was found that excellent fiber yield is obtained when the bath ratio is reduced.

[0118] Example 6: Use of ε-Caprolactone in a blended fabric composed of polyester and spandex

[0119] A flask containing a magnetic bar for stirring and 30 mL of ε-Caprolactone was placed in an oil bath at 180°C and stirred at 250 rpm to raise the temperature of the solvent. 0.3 g of a blended fabric consisting of 50% polyester and 50% spandex was added and stirred; 10 minutes after addition, all the spandex dissolved, and 22 minutes after addition, all the polyester fabric dissolved. The mixture was filtered using filter paper at room temperature to separate the filtrate and filtrate; the filtrate was then washed with water and ethanol and dried, resulting in 0.14 g of white granular polyester fabric. An antisolvent (water, ethanol, acetone, etc.) was added to the filtrate containing dissolved spandex to precipitate the spandex; the mixture was then filtered, washed, and dried to obtain 0.09 g of ivory-colored spandex in lumps.

[0120] Comparative Example 6-1: Use of ε-Caprolactone in Spandex Yarn

[0121] 15 mL of ε-Caprolactone was added to 0.15 g of spandex yarn, and the temperature was increased from 35°C to 115°C by 20°C every hour, and then from 115°C to 135°C by 10°C every hour. The yarn swelled after stirring for 1 hour at 115°C, and partially dissolved after stirring for 1 hour at 125°C. After stirring for 1 hour at 135°C, it was confirmed that all of the spandex had dissolved; the mixture was precipitated with an antisolvent to obtain 0.11 g of white spandex lumps.

[0122] Comparative Example 6-2: Use of ε-Caprolactone in Polyester Fabric

[0123] 15 mL of ε-Caprolactone was added to 0.15 g of polyester fabric, and the temperature was increased from 100°C to 180°C by 20°C every hour. When stirred for 1 hour at 140°C and 160°C, there was no change in the fabric, and when stirred for 10 minutes at 180°C, it was confirmed that the polyester fabric was completely dissolved. After cooling to a low temperature (room temperature), 0.14 g of white granular polyester was obtained.

[0124] Through this, it was found that when ε-Caprolactone is used as a solvent, polyester does not dissolve under conditions where spandex dissolves (135°C, 1 hour).

[0125] Experimental Example 7: Separation of polyester fibers and polyurethane fibers from blended fabric using Benzyl alcohol

[0126] Example 7-1: Use of Benzyl alcohol in a blended fabric of polyester and spandex (bath ratio 100)

[0127] A flask containing a magnetic bar for stirring and 30 mL of benzyl alcohol was placed in an oil bath at 180°C and stirred at 250 rpm to raise the temperature of the solvent. 0.3 g of a blended fabric consisting of 50% polyester and 50% spandex was added and stirred; 4 minutes after addition, all the spandex dissolved, and 10 minutes after addition, all the polyester fabric dissolved. The mixture was filtered using filter paper at room temperature to separate the filtrate and filtrate; the filtrate was then washed with water and ethanol and dried, resulting in 0.15 g of white granular polyester fabric. An antisolvent (water, ethanol, acetone, etc.) was added to the filtrate containing dissolved spandex to precipitate the spandex, and after filtration, washing and drying, 0.10 g of ivory-colored spandex lumps were obtained.

[0128] Example 7-2: Use of Benzyl alcohol in a blended fabric of polyester and spandex (bath ratio 20)

[0129] A flask containing a magnetic bar for stirring and 40 mL of benzyl alcohol was placed in an oil bath at 180°C and stirred at 250 rpm to raise the temperature of the solvent. 2.00 g of a blended fabric consisting of 75% polyester and 25% spandex was added and stirred for 30 minutes, during which both the spandex and polyester fabrics dissolved. As described above, since setting the bath ratio to 20 resulted in a high viscosity of the solution that was difficult to filter at room temperature, the solution was filtered using filter paper at 100 to 130°C to separate the filtrate and the filtrate. The filtrate was washed with water and ethanol and dried, resulting in 1.48 g of white granular polyester fabric. An antisolvent (water, ethanol, acetone, etc.) was added to the filtrate containing dissolved spandex to precipitate the spandex; after filtration, the solution was washed and dried to obtain 0.40 g of ivory-colored spandex lumps.

[0130] Comparative Example 7-1: Use of Benzyl Alcohol in Spandex Yarn

[0131] 15 mL of benzyl alcohol was added to 0.15 g of spandex yarn, and the temperature was increased from 65°C to 115°C by 10°C every hour. When stirred at 105°C for 1 hour, the yarn was partially dissolved, and after stirring at 115°C for 1 hour, it was confirmed that all of the spandex had dissolved. The mixture was then precipitated with an antisolvent to obtain 0.12 g of white granular spandex.

[0132] Comparative Example 7-2: Use of Benzyl Alcohol in Polyester Fabric

[0133] 15 mL of benzyl alcohol was added to 0.15 g of polyester fabric, and the temperature was increased from 125°C to 185°C by 20°C every hour. When stirred at 165°C for 1 hour, there was no change in the fabric, and when stirred at 185°C for 10 minutes, it was confirmed that the polyester fabric was completely dissolved. After cooling to a low temperature (room temperature), 0.15 g of white granular polyester was obtained.

[0134] Through this, it was found that when Benzyl alcohol is used as a solvent, polyester does not dissolve under conditions where spandex dissolves (115°C, 1 hour), and when the bath ratio is reduced from 100 to 20, the yield of polyester is similar, but the yield of spandex increases by about 15%, and it was found that excellent fiber yield is obtained when the bath ratio is reduced.

[0135] Experimental Example 8: Separation of polyester fibers and polyurethane fibers from a blended fabric using a cyclic amide solvent

[0136] Example 8: Use of ε-Caprolactam in a blended fabric composed of polyester and spandex

[0137] A flask containing a magnetic bar for stirring and 30 mL of ε-Caprolactam was placed in an 83°C oil bath and stirred at 250 rpm to raise the temperature of the solvent. 0.3 g of a blended fabric consisting of 50% polyester and 50% spandex was added and stirred for 1 hour. The mixture was filtered using filter paper at 80°C to separate the filtrate and the filtrate; the filtrate was then washed with water and ethanol and dried, resulting in 0.15 g of polyester retaining its original fabric form. An antisolvent (water, ethanol, acetone, etc.) was added to the filtrate containing dissolved spandex to precipitate the spandex, and after filtration, washing and drying were performed to obtain 0.09 g of white spandex in a lump.

[0138] Comparative Example 8-1: Use of ε-Caprolactam in Spandex Yarn

[0139] 16 mL of ε-Caprolactam was added to 0.16 g of spandex yarn, and the temperature was raised from 73°C to 83°C. When stirred for 1 hour at 73°C, the solvent was less dissolved and the mixture remained turbid; however, when stirred for 23 minutes at 83°C, the solvent melted and the yarn was completely dissolved. The mixture was precipitated with an antisolvent to obtain 0.13 g of white spandex lumps.

[0140] Comparative Example 8-2: Use of ε-Caprolactam in Polyester Fabric

[0141] 15 mL of ε-Caprolactam was added to 0.15 g of polyester fabric and the temperature was increased from 60°C to 180°C by 20°C every hour. The mixture was stirred at 180°C for 1 hour, but no dissolution occurred. After filtration, the fabric was washed and dried to obtain 0.15 g of polyester fabric.

[0142] Through this, it was found that when ε-Caprolactam is used as a solvent, polyester is not dissolved under conditions where spandex is dissolved (83°C, 23 min).

[0143] Example 9: Use of γ-Butyrolactam in a blended fabric composed of polyester and spandex

[0144] A flask containing a magnetic bar for stirring and 30 mL of γ-Butyrolactam was placed in a 95°C oil bath and stirred at 250 rpm to raise the temperature of the solvent. 0.3 g of a blended fabric consisting of 50% polyester and 50% spandex was added and stirred for 1 hour. The mixture was filtered using filter paper at 60°C to separate the filtrate and filtrate; the filtrate was then washed with water and ethanol and dried, resulting in 0.15 g of polyester retaining its original fabric form. The filtrate containing dissolved spandex was cooled to a low temperature (room temperature) to precipitate the spandex; after filtration, it was washed and dried to obtain 0.12 g of white spandex in a lump.

[0145] Comparative Example 9-1: Use of γ-Butyrolactam in Spandex Yarn

[0146] 15 mL of γ-Butyrolactam was added to 0.15 g of spandex yarn, and the temperature was increased from 65°C to 95°C by 10°C every hour. The yarn swelled after stirring for 1 hour at 75°C, became slightly cloudy after stirring for 1 hour at 85°C, and completely dissolved after stirring for 30 minutes at 95°C. The mixture was cooled to a low temperature (room temperature) to obtain 0.13 g of white spandex in a lump.

[0147] Comparative Example 9-2: Use of γ-Butyrolactam in Polyester Fabric

[0148] 15 mL of γ-Butyrolactam was added to 0.15 g of polyester fabric and the temperature was increased from 60°C to 180°C by 20°C every hour. The mixture was stirred at 180°C for 1 hour, but no dissolution occurred. After filtration, the fabric was washed and dried to obtain 0.15 g of polyester fabric.

[0149] Through this, it was found that when γ-Butyrolactam is used as a solvent, polyester is not dissolved under conditions where spandex dissolves (95°C, 30 min).

[0150] Experimental Example 9: Use of Cyclic Ketone-Based Solvents in Spandex Yarn

[0151] Comparative Example 10-1: Use of Cyclohexanone in Spandex Yarn

[0152] 0.15 g of spandex yarn was mixed with 15 mL of cyclohexanone, a cyclic ketone-based solvent, and the temperature was increased from room temperature to 115°C by 20°C every hour. The yarn showed no change at room temperature to 105°C, and no dissolution occurred when stirred at 115°C for 1 hour. After filtration, the yarn was washed and dried to obtain 0.15 g of spandex yarn. Through this, it was found that spandex does not dissolve when cyclohexanone is used as a solvent.

[0153] Comparative Example 10-2: Use of Cyclopentanone in Spandex Yarn

[0154] 0.15 g of spandex yarn was mixed with 15 mL of cyclopentanone, a cyclic ketone solvent, and heated from room temperature to 125°C. The yarn unraveled at 65 to 85°C, swelled when stirred for 3 hours at 95 to 115°C, and rapidly dissolved and shortened when stirred for 20 minutes at 125°C. When stirred for 50 minutes at 125°C, all of the spandex dissolved, but yellowing occurred from the moment the yarn was added to cyclopentanone, and the obtained spandex was also yellowed. Based on this, it appears that if cyclopentanone is used as a solvent, dissolution of spandex is possible, but it will be difficult to utilize it as a material due to yellowing.

[0155] Experimental Example 10: Use of Cyclic amine-based solvent for spandex yarn

[0156] Comparative Example 11: Use of Azopane in Spandex Yarn

[0157] 15 mL of Azopane, a cyclic amine solvent, was added to 0.15 g of spandex yarn, and the temperature was increased from 40°C to 140°C by 20°C every hour. The mixture was stirred for 1 hour at 140°C, but no dissolution occurred. After filtration, the mixture was washed and dried to obtain 0.15 g of spandex yarn. Through this, it was found that spandex does not dissolve when Azopane is used as a solvent.

[0158] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0159] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0160] The present invention will be described in more detail below. However, the present invention may be implemented in various different forms and is not limited by the embodiments described herein, and is defined only by the claims set forth below.

[0161] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0162] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0163]

[0164] (1) First embodiment of the present invention: A method for separating cellulose fibers from a blended fiber containing cellulose-based fibers

[0165] The first aspect of the present invention is,

[0166] A method for separating cellulose fibers is provided, comprising the steps of: mixing a quaternary ammonium alcohol compound and an organic acid to form a co-solvent; immersing a raw fiber containing at least a cellulose component in the co-solvent; reacting the raw fiber with the co-solvent to selectively separate the cellulose fiber; and recovering the separated cellulose fiber; wherein the co-solvent is characterized by mixing the quaternary ammonium alcohol compound and the organic acid in a ratio of 1 to 3 to 3 to 1.

[0167] Hereinafter, a method for separating cellulose fibers according to the first aspect of the present invention will be described in detail.

[0168] In one embodiment of the present invention, the step of forming the co-solvent may be performed by adding water to dissolve the quaternary ammonium alcohol compound and the organic acid, and then removing the water by vacuum distillation. The water may be tap water, distilled water (DW), or ultrapure water (DI water, deionized water), and there are no particular restrictions on the type of apparatus used for vacuum distillation as long as it is capable of removing water; preferably, a rotary evaporator may be used. The vacuum distillation conditions are not particularly limited, but to give a specific example, the pressure during vacuum distillation may be 0.1 to 200 mbar, more preferably 1 to 90 mbar, and the temperature during vacuum distillation may be 20 to 100°C, more preferably 40 to 60°C.

[0169] In one embodiment of the present invention, the step of forming the co-solvent may be performed by raising the quaternary ammonium alcohol compound and the organic acid to a predetermined temperature and mixing them for a predetermined time to form the co-solvent. The predetermined temperature may be in the range of 60 to 100°C, and preferably may be performed at 70 to 90°C. If the temperature is below this range, the components may not sufficiently melt or interact, making it difficult to form the co-solvent, resulting in a non-uniform mixture and potentially reducing the effectiveness as a solvent. If the temperature exceeds this range, the components may decompose or be chemically altered, and functionality at high temperatures may be lost. Additionally, the bonding network may be destroyed, which may degrade the properties of the DES, such as solubility and environmental friendliness. The above-mentioned predetermined time may be in the range of 1 to 3 hours, and preferably may be performed for 1 to 2 hours. If the above-mentioned range is exceeded, the bonding network between the quaternary ammonium alcohol compound and the organic acid may not be fully formed, and as a result, the properties of DES, such as solvent capability and low melting point, may not be sufficiently expressed. Additionally, a non-uniform phase may be formed because the constituent components are not completely dissolved.

[0170] In one embodiment of the present invention, the co-solvent may be a mixture of a quaternary ammonium alcohol compound and an organic acid in a ratio of 1 to 3:3 to 1, and more preferably a ratio of more than 1 and less than or equal to 3:1. If the ratio of the organic acid deviates from a certain range, the degree of yellowing may increase, and yellowed cellulose may be difficult to use as a material, which may limit the range of applications.

[0171] In one embodiment of the present invention, the step of selectively separating cellulose fibers by reacting the raw fiber with a co-solvent may be performed for 0.5 to 3 hours. For example, the reaction time between the raw fiber and the co-solvent may preferably be performed for 1 to 2 hours. If the reaction time is less than the above range, the co-solvent may not interact sufficiently with the raw fiber, which may reduce the efficiency of separating the cellulose fibers, and due to incomplete separation, the uniformity of the cellulose fibers may be reduced and processability may be poor. If the reaction time exceeds the above range, the particle size of the separated fibers may decrease, and the degree of yellowing may increase, making it difficult to use as a material and thus limiting the range of applications.

[0172] In one embodiment of the present invention, the step of selectively separating cellulose fibers by reacting the raw fiber with a co-solvent may be performed at a temperature greater than 110°C and less than 150°C. For example, the reaction temperature between the raw fiber and the co-solvent may preferably be performed at 120 to 130°C, and if it is below this range, the co-solvent may not interact sufficiently with the raw fiber, resulting in a slow reaction rate and incomplete separation of cellulose fibers. If it exceeds this range, yellowing may occur, which may adversely affect fiber quality, and by-products may be generated due to excessive decomposition.

[0173] In one embodiment of the present invention, in the step of selectively separating cellulose fibers by reacting the raw fiber with the co-solvent; the co-solvent may be added in a bath ratio of 10 to 100 parts by weight per 1 part by weight of the raw fiber. For example, the co-solvent may preferably be in a bath ratio of 10 to 60 parts by weight, and more preferably 10 to 30 parts by weight per 1 part by weight of the raw fiber. If the amount of the co-solvent is insufficient, it may not come into sufficient contact with the raw fiber, and thus the separation of the cellulose fibers may not be properly achieved; and if the amount of the co-solvent is excessively large, an unnecessary amount may be used in the reaction, which may increase process costs.

[0174] In one embodiment of the present invention, the cellulose fiber may be selected from the group consisting of pulp fiber, purified cellulose, and pulp board.

[0175] In one embodiment of the present invention, the raw fiber may include cellulose fibers and synthetic fibers, and other fibers excluding the cellulose fibers may be preserved without being damaged by a co-solvent. The cellulose fibers may include one or more selected from the group consisting of natural fibers such as cotton, linen, and hemp, and regenerated fibers such as rayon, modal, and lyocell, and the synthetic fibers may include one or more selected from the group consisting of artificial fibers such as polyester, spandex, nylon, and acrylic.

[0176] In one embodiment of the present invention, the method may further include the step of selectively separating cellulose fibers by reacting the raw fibers with a co-solvent; and the step of recovering the used co-solvent thereafter.

[0177] In one embodiment of the present invention, the quaternary ammonium alcohol compound may be choline chloride, choline iodide, choline hydroxide, or choline bitartrate. The quaternary ammonium alcohol compound may preferably be choline chloride and may be used as a hydrogen bond acceptor. Choline chloride can effectively inhibit the formation of cyclic anhydrides of organic acids and allow for the preservation of more carboxyl groups. Cl of choline chloride - Ions can form anionic hydrogen bond interactions with the carboxyl groups of organic acids.

[0178] In one embodiment of the present invention, the organic acid may be an organic acid having n carboxyl groups, where n is an integer from 1 to 5. In a preferred embodiment of the present invention, the organic acid may be citric acid and may be used as a hydrogen bond donor. Citric acid is not only an environmentally friendly organic acid but also a tricarboxylic acid compound rich in carboxyl groups, so it can break the hydrogen bond network of cellulose, break it into individual molecules, and form hydrogen bonds with the hydroxyl groups of cellulose.

[0179]

[0180] The second aspect of the present invention is,

[0181] The present invention provides an apparatus for separating and recovering cellulose fibers from raw fibers, comprising: a co-solvent forming unit that mixes the quaternary ammonium alcohol compound and the organic acid, each having a nozzle for introducing a quaternary ammonium alcohol compound and an organic acid; a reaction unit that extends and is connected from the outlet nozzle of the co-solvent forming unit and is equipped with a co-solvent injection nozzle to supply the formed co-solvent and a raw fiber input port for introducing the raw fiber, wherein a reaction between the raw fiber and the co-solvent takes place inside; and a cellulose recovery unit that extends and is connected from the outlet of the reaction unit and is connected to transfer the separated cellulose to perform solid-liquid separation, wherein the co-solvent is characterized in that the quaternary ammonium alcohol compound and the organic acid are mixed in a ratio of 1 to 3:3 to 1.

[0182] Detailed explanations have been omitted for parts that overlap with the first aspect of the present invention, but the content described in the first aspect of the present invention may be applied equally even if such explanations are omitted in the second aspect.

[0183]

[0184] (2) Second embodiment of the present invention: a method for separating polyurethane fibers

[0185] The third aspect of the present invention is,

[0186] A method for separating polyurethane fibers from raw fibers is provided, comprising the steps of: preparing an extraction solvent; immersing raw fibers containing at least polyurethane fibers and polyester fibers in the extraction solvent; contacting the raw fibers with the extraction solvent to selectively dissolve the polyurethane fibers; and filtering the solution in which the polyurethane fibers are dissolved to recover the separated polyurethane fibers.

[0187] Hereinafter, a method for separating polyurethane fibers from raw fibers according to the third aspect of the present invention will be described in detail.

[0188] In one embodiment of the present invention, the polyurethane fiber may include a polyurethane having soft or hard properties and may have a non-foamed structure having elasticity and stretchability, mainly consisting of a continuous polymer phase. The polyurethane fiber may be in the form of a block copolymer mainly containing urethane bonds, and may be composed of a rigid hard segment (HS) and a soft segment (SS) that imparts elasticity. Thanks to these structural characteristics, it may have high stretchability and resilience, and depending on the specific application, it may be blended with polymers such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) or utilized in the form of a composite material.

[0189] In one embodiment of the present invention, the polyester fiber may comprise a polymer formed by the condensation polymerization of a dicarboxylic acid and a dialol, and examples of said polymer may be selected from polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and combinations thereof.

[0190] In one embodiment of the present invention, the step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent may be performed at a temperature of 60°C to 175°C. In a preferred embodiment of the present invention, the dissolution temperature may be 80°C to 140°C, and more preferably 90°C to 140°C. If the above range is exceeded, the polyester fabric may be dissolved, and at high temperatures, not only the polyurethane-based fibers but also the polyester-based fibers may be subject to deterioration or physical damage, and the dissolution ability may be reduced or the reaction efficiency may decrease due to the thermal decomposition of the solvent. If the above range is below, the dissolution of polyurethane-based fibers may not be properly carried out, making selective separation difficult, and if the temperature is lowered, the viscosity of the solvent increases, making contact with the fiber surface inefficient, which slows down the solvent diffusion rate, causing the dissolution reaction to be delayed or become non-uniform.

[0191] In one embodiment of the present invention, the method may further include the step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent; and the step of subsequently increasing the temperature to 145°C to 200°C to further dissolve polyester fibers. In a preferred embodiment of the present invention, the dissolution temperature may be 160°C to 190°C, and more preferably 170°C to 185°C. Within the above temperature range, both polyester-based fibers and polyurethane-based fibers may be in a dissolved state. If the above range is exceeded, thermal decomposition of the fibers may occur, resulting in loss of physical properties or alteration of the chemical structure; furthermore, if the thermal stability of the solvent is compromised due to high temperature, solvent efficiency may decrease and the quality of the recycling process may deteriorate. If the above range is below, the dissolution of polyester fibers may be incomplete, and the dissolution time may become excessively long, thereby reducing process efficiency. The extraction solvent may comprise a substituted or unsubstituted pentagonal or heptagonal cyclic ester, or an alcohol compound containing an aromatic group, and in one preferred embodiment of the present invention, the extraction solvent may comprise γ-butyrolactone, ε-caprolactone, or benzyl alcohol.

[0192] In one embodiment of the present invention, the method may further include the step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent; and the step of subsequently raising the temperature to 145°C to 200°C to promote the selective separation of polyurethane-based fibers. In a preferred embodiment of the present invention, the temperature may be 160°C to 190°C, and more preferably 170°C to 180°C. If the temperature falls outside this range, thermal decomposition of the fibers may occur, resulting in a loss of physical properties or an alteration of the chemical structure; furthermore, if the thermal stability of the solvent is compromised due to high temperatures, the solvent efficiency may decrease and the quality of the recycling process may deteriorate. The extraction solvent may include a substituted or unsubstituted pentagonal or heptagonal cyclic amide compound. In a preferred embodiment of the present invention, the extraction solvent may include ε-caprolactam or γ-butyrolactam. When using the above solvent, when the temperature is raised to 145°C to 200°C, the polyester fibers are not dissolved and only the polyurethane fibers are dissolved, and selective separation of the polyurethane fibers can be promoted.

[0193] In one embodiment of the present invention, the step of selectively dissolving the polyurethane-based fiber by contacting the raw fiber with an extraction solvent may be performed for 0.1 to 4 hours. In a preferred embodiment of the present invention, the performance time may be 0.1 to 3 hours, and more preferably 0.1 to 1.5 hours. If the range is exceeded, the possibility of thermal decomposition of the polyurethane-based fiber may increase, yellowing problems may occur, and the composition may change due to the evaporation of the solvent. If the range is below, the polyurethane-based fiber may not be completely dissolved, and the polyurethane may remain in a lump form or exist in a gel state, causing problems in subsequent processes.

[0194] In one embodiment of the present invention, in the step of selectively dissolving polyurethane-based fibers by contacting the raw fibers with an extraction solvent, the extraction solvent may be added in a bath ratio of 5 to 150 parts by weight per 1 part by weight of the raw fibers. In a preferred embodiment of the present invention, the extraction solvent may be added in a bath ratio of 10 to 120 parts by weight per 1 part by weight of the raw fibers, and more preferably, the extraction solvent may be in a bath ratio of 20 to 100 parts by weight. If the above range is exceeded, the dissolution rate of the polyurethane-based fibers may be slowed down, and the dissolution uniformity may be reduced, resulting in a longer dissolution time. If the above range is below, the polyurethane-based fibers may not be completely dissolved, and the dissolved polyurethane may aggregate into a highly viscous gel form, making stirring difficult and reducing the uniformity of mixing.

[0195] In one embodiment of the present invention, a solution in which polyurethane-based fibers are dissolved can be filtered to separate the filtrate, which consists of polyester, and the filtrate, in which polyurethane is dissolved. The filtrate can be washed using a solvent such as water or ethanol, and then a fiber from which polyurethane has been removed can be obtained through a drying process. The filtrate can be cooled or an antisolvent such as water, ethanol, or acetone can be used to precipitate and deposit the polyurethane-based fibers, and the polyurethane fibers can be recovered through a filtration, washing, and drying process.

[0196] In one embodiment of the present invention, the method may further include the step of selectively dissolving the polyurethane-based fiber by contacting the raw fiber with an extraction solvent; and the step of recovering the used extraction solvent by distillation thereafter.

[0197]

[0198] The fourth aspect of the present invention is,

[0199] The present invention provides an extraction solution composition for separating polyurethane fibers from raw fibers, comprising: raw fibers containing at least polyurethane fibers and polyester fibers; and an extraction solvent; wherein the extraction solvent comprises a substituted or unsubstituted pentagonal or heptagonal cyclic ester or an alcohol compound containing an aromatic group.

[0200] Detailed explanations have been omitted for parts that overlap with the third aspect of this invention; however, the content explained regarding the third aspect of this invention may be applied equally even if such explanations are omitted in the fourth aspect.

[0201] Hereinafter, an extraction solution composition for separating polyurethane fibers from raw fibers according to the fourth aspect of the present invention will be described in detail.

[0202] In one embodiment of the present invention, the polyurethane-based fiber may be in a dissolved state at a temperature of 60°C to 175°C. In a preferred embodiment of the present invention, the temperature may be 80°C to 140°C, and more preferably 90°C to 140°C. If the temperature exceeds the above range, the polyester fabric may be dissolved, and at high temperatures, not only the polyurethane-based fiber but also the polyester-based fiber may be subject to deterioration or physical damage, and the dissolution ability may be reduced or the reaction efficiency may decrease due to the thermal decomposition of the solvent. If the temperature is below the above range, the polyurethane-based fiber may not be properly dissolved, selective separation may be difficult, and the polyurethane may remain in a lump form or exist in a gel state, causing problems in subsequent processes.

[0203] In one embodiment of the present invention, the polyester fibers and polyurethane-based fibers may both be in a dissolved state at a temperature of 145°C to 200°C. In a preferred embodiment of the present invention, the temperature may be 160°C to 190°C, and more preferably 170°C to 185°C. If the temperature exceeds the above range, thermal decomposition of the fibers may occur, resulting in a loss of physical properties or an alteration of the chemical structure; furthermore, if the thermal stability of the solvent is compromised due to the high temperature, the solvent efficiency may decrease and the quality of the recycling process may deteriorate. If the temperature is below the above range, the dissolution of the polyester fibers may be incomplete when using the extraction solution composition, and the dissolution time may become excessively long, thereby reducing process efficiency. The extraction solvent may comprise a substituted or unsubstituted pentagonal or heptagonal cyclic ester, or an alcohol compound containing an aromatic group, and in one preferred embodiment of the present invention, the extraction solvent may comprise γ-butyrolactone, ε-caprolactone, or benzyl alcohol.

[0204]

[0205] The fifth aspect of the present invention is,

[0206] The present invention provides an extraction solution composition for separating polyurethane fibers from raw fibers, comprising: raw fibers containing at least polyurethane fibers and polyester fibers; and an extraction solvent; wherein the extraction solvent comprises a substituted or unsubstituted pentagonal or heptagonal cyclic amide compound.

[0207] Detailed explanations have been omitted for parts that overlap with the third and fourth aspects of this invention; however, the explanations provided for the third and fourth aspects of this invention may be applied equally to the fifth aspect even if such explanations are omitted.

[0208] Hereinafter, an extraction solution composition for separating polyurethane fibers from raw fibers according to the fifth aspect of the present invention will be described in detail.

[0209] In one embodiment of the present invention, the polyurethane-based fiber may be in a dissolved state at a temperature of 60°C to 175°C. In a preferred embodiment of the present invention, the temperature may be 80°C to 140°C, and more preferably 90°C to 140°C. If the temperature exceeds the above range, the polyester fabric may be dissolved, and at high temperatures, not only the polyurethane-based fiber but also the polyester-based fiber may be subject to deterioration or physical damage, and the dissolution ability may be reduced or the reaction efficiency may decrease due to the thermal decomposition of the solvent. If the temperature is below the above range, the polyurethane-based fiber may not be properly dissolved, selective separation may be difficult, and the polyurethane may remain in a lump form or exist in a gel state, causing problems in subsequent processes.

[0210] In one embodiment of the present invention, insolubility of polyester fibers and dissolution of polyurethane fibers may occur at a temperature of 145°C to 200°C. In a preferred embodiment of the present invention, the temperature may be 160°C to 190°C, and more preferably 170°C to 180°C. If the temperature falls outside this range, thermal decomposition of the fibers may occur, resulting in loss of physical properties or alteration of the chemical structure; furthermore, if the thermal stability of the solvent is compromised due to high temperatures, solvent efficiency may decrease and the quality of the recycling process may deteriorate. The extraction solvent may include a substituted or unsubstituted pentagonal or heptagonal cyclic amide compound. In a preferred embodiment of the present invention, the extraction solvent may include ε-caprolactam or γ-butyrolactam.

[0211]

[0212] The sixth aspect of this invention is,

[0213] The present invention provides a device for separating polyurethane fibers from raw fibers, comprising: an extraction solvent storage unit for storing an extraction solvent; a reaction unit extending from and connected to an outlet nozzle of the extraction solvent storage unit, and equipped with an extraction solvent injection nozzle to supply the formed extraction solvent and a raw fiber input port for introducing the raw fiber, wherein a reaction between the raw fiber and the extraction solvent takes place inside; and a polyurethane fiber separation unit extending from and connected to an outlet of the reaction unit, wherein the separated polyurethane fiber or polyester fiber is conveyed and solid-liquid separation is performed.

[0214] Detailed explanations have been omitted for parts that overlap with the third, fourth, and fifth aspects of this invention; however, the explanations provided for the third, fourth, and fifth aspects of this invention may be applied equally to the sixth aspect even if such explanations are omitted.

[0215] According to one embodiment of the first embodiment of the present invention, raw fibers can be effectively separated and recycled by using DES to selectively separate cellulose-based fibers while leaving polyester behind.

[0216] According to one embodiment of the second aspect of the present invention, the solvents of the benzyl alcohol, lactam, and lactone series of the present invention, unlike the widely used DMF and MEK, are not regulated as toxic substances or accident prevention substances and can be used without environmental and legal restrictions. This can contribute to protecting the health of workers and implementing safer recycling processes in industrial sites, so it can be considered to have industrial applicability.

Claims

A step of forming a cosolvent by mixing a 1.quaternary ammonium alcohol compound and an organic acid; A step of immersing raw fibers containing at least a cellulose component in the above co-solvent; A step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent; and Step of recovering separated cellulose fibers; Includes, A method for separating cellulose fibers, characterized in that the above-mentioned co-solvent is a mixture of a quaternary ammonium alcohol compound and an organic acid in a ratio of 1 to 3:3 to 1.

2. In Paragraph 1, The step of forming the above co-solvent; A method for separating cellulose fibers, characterized by forming a cosolvent by adding water to dissolve the quaternary ammonium alcohol compound and the organic acid, and then removing the water by vacuum distillation.

3. In Paragraph 1, The step of forming the above co-solvent; A method for separating cellulose fibers, characterized by heating the above-mentioned quaternary ammonium alcohol compound and organic acid to a predetermined temperature and mixing them for a predetermined time to form a co-solvent.

4. In Paragraph 3, A method for separating cellulose fibers, characterized in that the above-mentioned predetermined temperature is a temperature in the range of 60 to 100℃.

5. In Paragraph 3, A method for separating cellulose fibers, characterized in that the above-mentioned predetermined time is a time in the range of 1 to 3 hours.

6. In Paragraph 1, A method for separating cellulose fibers, characterized in that the above-mentioned co-solvent is a mixture of a quaternary ammonium alcohol compound and an organic acid in a ratio of more than 1 and less than or equal to 3:

1.

7. In Paragraph 1, A method for separating cellulose fibers, characterized in that the step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent is performed for 0.5 to 3 hours.

8. In Paragraph 1, A method for separating cellulose fibers, characterized in that the step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent is performed at a temperature greater than 110°C and less than 150°C.

9. In Paragraph 1, In the step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent, A method for separating cellulose fibers, wherein the co-solvent is added in a bath ratio of 10 to 100 parts by weight per 1 part by weight of the raw fiber.

10. In Paragraph 1, A method for separating cellulose fibers, characterized in that the cellulose fibers are selected from the group consisting of pulp fibers, purified cellulose, and pulp boards.

11. In Paragraph 1, The above raw fibers include cellulose fibers and synthetic fibers, and A method for separating cellulose fibers, characterized in that some fibers are preserved without being damaged by the co-solvent.

12. In Paragraph 1, A step of selectively separating cellulose fibers by reacting the above raw fibers with a co-solvent; after A method for separating cellulose fibers, further comprising the step of recovering the used co-solvent.

13. In Paragraph 1, A method for separating cellulose fibers, characterized in that the above-mentioned quaternary ammonium alcohol compound is choline chloride, choline iodide, choline hydroxide, or choline bitartrate.

14. In Paragraph 1, A method for separating cellulose fibers, characterized in that the above organic acid is an organic acid having n carboxyl groups. (Here, n is an integer from 1 to 5.) 15. In Paragraph 1, A method for separating cellulose fibers, characterized in that the above organic acid is citric acid.

16. A device for separating and recovering cellulose fibers from raw fibers, A co-solvent forming unit equipped with nozzles for introducing a quaternary ammonium alcohol compound and an organic acid, respectively, and mixing the quaternary ammonium alcohol compound and the organic acid; A reaction section extending from and connected to the outlet nozzle of the co-solvent forming section, and equipped with a co-solvent injection nozzle to supply the formed co-solvent, and a raw fiber inlet for introducing raw fibers, wherein a reaction between the raw fibers and the co-solvent takes place inside; A cellulose recovery unit extending from and connected to the outlet of the above reaction unit, to which separated cellulose is transported and solid-liquid separation is performed; Includes, An apparatus for separating and recovering cellulose fibers from raw fibers, characterized in that the above-mentioned co-solvent comprises a quaternary ammonium alcohol compound and an organic acid mixed in a ratio of 1 to 3:3 to 1.

17. Step of preparing the extraction solvent; A step of immersing raw fibers containing at least polyurethane fibers and polyester fibers in the above extraction solvent; A step of selectively dissolving polyurethane-based fibers by contacting the above raw fibers with an extraction solvent; and A step of recovering separated polyurethane fibers by filtering a solution in which polyurethane fibers are dissolved; including, Method for separating polyurethane fibers from raw fibers.

18. In Paragraph 17, A method for separating polyurethane fibers from raw fibers, wherein the step of selectively dissolving polyurethane fibers by contacting the raw fibers with an extraction solvent is performed at a temperature of 80°C to 140°C.

19. In Paragraph 18, A step of selectively dissolving polyurethane-based fibers by contacting the above raw fibers with an extraction solvent; after A method for separating polyurethane fibers, further comprising the step of further dissolving the polyester fibers by raising the temperature to 145℃ to 200℃.

20. In Paragraph 18, A step of selectively dissolving polyurethane-based fibers by contacting the above raw fibers with an extraction solvent; after A method for separating polyurethane fibers, further comprising the step of raising the temperature to 145℃ to 200℃ to promote the selective separation of polyurethane-based fibers.

21. In Paragraph 19, A method for separating polyurethane fibers from raw fibers, wherein the extraction solvent comprises a substituted or unsubstituted pentagonal or heptagonal cyclic ester, or an alcohol compound containing an aromatic group.

22. In Paragraph 19, A method for separating polyurethane fibers from raw fibers, wherein the extraction solvent comprises γ-butyrolactone, ε-caprolactone, or benzyl alcohol.

23. In Paragraph 20, A method for separating polyurethane fibers from raw fibers, wherein the extraction solvent comprises a substituted or unsubstituted pentagonal or heptagonal cyclic amide compound.

24. In Paragraph 20, A method for separating polyurethane fibers from raw fibers, wherein the extraction solvent comprises ε-caprolactam or γ-butyrolactam.

25. In Paragraph 17, A method for separating polyurethane fibers from raw fibers, characterized in that the step of selectively dissolving polyurethane fibers by contacting the raw fibers with an extraction solvent is performed for 0.1 to 4 hours.

26. In Paragraph 17, In the step of selectively dissolving polyurethane-based fibers by contacting the above raw fibers with an extraction solvent, A method for separating polyurethane fibers from raw fibers, wherein the extraction solvent is introduced in a bath ratio of 5 to 150 parts by weight per 1 part by weight of the raw fiber.

27. In Paragraph 17, A step of selectively dissolving polyurethane-based fibers by contacting the above raw fibers with an extraction solvent; after A method for separating polyurethane fibers from raw fibers, further comprising the step of recovering the used extraction solvent by distillation.

28. Raw fibers containing at least polyurethane-based fibers and polyester fibers; and Extraction solvent; An extraction solution composition for separating polyurethane fibers from raw fibers, comprising The above extraction solvent is an extraction solution composition for separating polyurethane fibers from raw fibers, comprising a substituted or unsubstituted pentagonal or heptagonal cyclic ester or an alcohol compound containing an aromatic group.

29. Raw fibers containing at least polyurethane-based fibers and polyester fibers; and Extraction solvent; An extraction solution composition for separating polyurethane fibers from raw fibers, comprising The above extraction solvent is an extraction solution composition for separating polyurethane fibers from raw fibers, comprising a substituted or unsubstituted pentagonal or heptagonal cyclic amide compound.

30. In Paragraph 28 or 29, An extraction solution composition for separating polyurethane fibers from raw fibers, characterized in that the polyurethane fibers are in a dissolved state at a temperature of 80℃ to 140℃.

31. In Paragraph 28, An extraction solution composition for separating polyurethane fibers from raw fibers, characterized in that both the polyester fibers and the polyurethane fibers are dissolved at a temperature of 145℃ to 200℃.

32. In Paragraph 29, An extraction solution composition for separating polyurethane fibers from raw fibers, characterized by the insolubility of polyester fibers and the dissolution of polyurethane fibers at a temperature of 145℃ to 200℃.

33. A device for separating polyurethane fibers from raw fibers, Extraction solvent storage unit for storing extraction solvent; A reaction section extending from and connected to the outlet nozzle of the extraction solvent storage section above, and equipped with an extraction solvent injection nozzle to supply the formed extraction solvent and a raw fiber input port for introducing raw fibers, wherein a reaction between the raw fibers and the extraction solvent takes place inside; A polyurethane fiber separation unit extending from and connected to the outlet of the above reaction unit, wherein separated polyurethane fibers or polyester fibers are transported and solid-liquid separation is performed; A device for separating polyurethane fibers from raw fibers, comprising

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