Processing method for mixed fibers containing polyester fibers and non-polyester fibers, and mixed fiber processing device using same

Abstract

Disclosed are: a processing method for mixed fibers containing polyester fibers and non-polyester fibers; and a mixed fiber processing device using the same. A processing method according to the present invention includes: a step for obtaining a reaction mixture liquid by irradiating, with microwaves, a mixture of an alkylene glycol having 2-6 carbon atoms and mixed fibers containing polyester fibers and non-polyester fibers in a state in which the alkylene glycol is at a temperature of 180-250°C; and a step for separating said reaction mixture liquid into solid components and liquid components. According to the present invention, it is possible to liquefy components derived from the polyester fibers while retaining the non-polyester fibers in the solid components of the mixed fibers. As a result, said mixed fibers can be separated into the polyester fibers and non-polyester fibers, and after the separation, the polyester fibers and the non-polyester fibers can be efficiently regenerated and / or recycled.

Description

Method for treating mixed fibers containing polyester fibers and non-polyester fibers, and mixed fiber treatment device using the same

[0001] The present invention relates to a method for treating a mixed fiber containing polyester fibers and non-polyester fibers, and a mixed fiber treatment device using the same.

[0002] The apparel industry, as an industry with a high environmental impact, faces the urgent need to resolve social issues. Many apparel products are used for a short period of time or are discarded immediately without being used at all. The production of these apparel products also poses a problem, as it uses a large amount of energy and water resources, making resource recycling a major priority.

[0003] Among these, apparel products made of 100% cotton or polyester (often polyester fibers made of polyethylene terephthalate (PET)) are relatively easy to recycle. Polyester in particular can be chemically recycled through chemical decomposition, and apparel products made of recycled polyester are already on the market.

[0004] On the other hand, blended fibers spun from a mixture of staple fibers such as cotton and filaments such as polyester are also used in many apparel products. For example, cotton fibers have excellent moisture absorption properties but are prone to wrinkling, while products made from polyester fibers are wrinkle-resistant but lack moisture absorption. Each fiber has its own advantages and disadvantages. For this reason, cotton fibers and polyester fibers are sometimes blended to form blended fibers (or blended yarns), which are then used in apparel products. In fact, cotton-polyester blended fibers are used in many apparel products, such as polo shirts and dress shirts.

[0005] However, when apparel products made from such blended fibers are discarded, there is no established technology to separate the cotton and polyester and recycle them.

[0006] Because cotton (cellulose) dissolves in ionic liquids, a technique has been proposed in which cotton / polyester blended fibers are dissolved in ionic liquids and separated into a cotton solution and polyester fibers (Patent Document 1). However, ionic liquids are expensive, and it is not easy to regenerate cotton fibers from such a cotton-ionic liquid solution.

[0007] Therefore, there is a need in the art for the establishment of a technique for separating cotton and polyester fibers from blended fibers, taking into consideration the regeneration of these fibers.

[0008] Patent No. 5824766

[0009] The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a method for treating mixed fibers containing polyester fibers and non-polyester fibers, which can easily separate components derived from the polyester fibers and components derived from the non-polyester fibers from mixed fibers containing polyester fibers and non-polyester fibers or from products containing such fibers, and a mixed fiber treatment device using the same.

[0010] The present invention is a method for treating a mixed fiber containing polyester fiber and non-polyester fiber, comprising the steps of: irradiating a mixture of the mixed fiber and an alkylene glycol having 2 to 6 carbon atoms with microwaves at a temperature of 180°C to 250°C to obtain a reaction mixture; and separating the reaction mixture into a solid component and a liquid component.

[0011] In one embodiment, the mixture contains a transesterification catalyst.

[0012] In a further embodiment, the transesterification catalyst is an acetate salt.

[0013] In one embodiment, the alkylene glycol is ethylene glycol.

[0014] In one embodiment, the polyester fibers are terephthalate-based fibers.

[0015] In a further embodiment, the terephthalate-based fiber is at least one fiber selected from the group consisting of polyethylene terephthalate (PET) fiber, polybutylene terephthalate (PBT) fiber, and polytrimethylene terephthalate (PTT) fiber.

[0016] In a further embodiment, the terephthalate-based fibers are polyethylene terephthalate (PET) fibers.

[0017] In yet a further embodiment, the method of the present invention further comprises the step of recovering bis(2-hydroxyethyl) terephthalate (BHET) from the liquid component by recrystallization.

[0018] In one embodiment, the non-polyester fibers comprise natural fibers.

[0019] The present invention also provides an apparatus for treating a mixed fiber containing polyester fibers and non-polyester fibers, the apparatus comprising: a reaction vessel containing a mixture of the mixed fiber and an alkylene glycol having 2 to 6 carbon atoms; microwave generating means for irradiating the mixture with microwaves to obtain a reaction mixture; and means for separating the reaction mixture into a solid component and a liquid component.

[0020] In one embodiment, the reaction system further comprises a settling tank for containing the liquid component separated from the reaction mixture and promoting the formation of a precipitate.

[0021] In a further embodiment, the method further comprises means for separating the precipitate from the settling tank and receiving a recovered liquid containing the alkylene glycol.

[0022] In yet a further embodiment, the method further comprises means for returning the alkylene glycol contained in the recovered solution to the reaction vessel.

[0023] According to the present invention, components derived from recycled and / or reusable polyester fibers and components derived from non-polyester fibers can be easily separated from mixed fibers or products containing such fibers. Furthermore, the mixed fiber treatment that enables this separation can be performed in a relatively short time. The treatment method of the present invention can use widely available chemicals, and high treatment costs can be avoided.

[0024] FIG. 1 is a schematic diagram of an example of a mixed fiber treatment device of the present invention for explaining the device; FIG. 2 is an optical microscope photograph of the compound (Ec1) obtained in Example 1; FIG. 3 is a graph showing the IR spectra of pure polyethylene terephthalate (PET), the solid component (fiber) (Es1) obtained in Example 1, and pure cellulose; (a) is an electron microscope photograph of the solid component (fiber) (Es1) obtained in Example 1, and (b) is an electron microscope photograph of the mixed fibers in the white polo shirt sample before treatment used in Example 1; (a) is an electron microscope photograph of the initial distillate liquid obtained by distilling the reaction solution obtained in Example 7; １ 1B is a graph showing the H-NMR spectrum of the main fraction obtained by distilling the reaction solution obtained in Example 7; １ 1A is a graph showing the H-NMR spectrum of the main fraction (ethylene glycol) obtained by distilling the reaction mixture obtained in Example 7. ３ During １ 1A and 1B are graphs showing the H-NMR spectrum of (a) commercially available reagent grade BHET (bis(2-hydroxyethyl) terephthalate) in deuterated DMSO; １ 1C is a graph showing the H-NMR spectrum of the washed residue obtained in Example 7 in deuterated DMSO; １1 is a graph showing H-NMR spectra.

[0023] FIG. 1 is a graph showing IR spectra of the solid component (fibers) obtained using recovered ethylene glycol in Example 8, the solid component (fibers) obtained using ethylene glycol (fresh solution) in Comparative Example 4, and the work glove sample in Reference Example 2.

[0024] FIG. 1 is a graph showing IR spectra of BHET obtained using recovered ethylene glycol in Example 8, BHET obtained using ethylene glycol (fresh solution) in Comparative Example 4, and BHET recovered from the washed distillation residue obtained in Example 7.

[0025] The present invention will be described in detail below.

[0026] (Method for Treating Mixed Fibers) The method of the present invention is used to treat mixed fibers containing polyester fibers and non-polyester fibers.

[0027] The polyester fiber in the present invention is a filament (long fiber) whose main component is a polymer (polyester) obtained by a dehydration condensation reaction between a dicarboxylic acid and a diol, and examples thereof include terephthalate-based fibers containing terephthalate units in their chemical structure. Examples of terephthalate-based fibers include polyethylene terephthalate (PET) fibers, polybutylene terephthalate (PBT) fibers, and polytrimethylene terephthalate (PTT) fibers, as well as combinations thereof. The polyester fiber is preferably polyethylene terephthalate fiber because it is frequently used in apparel products, particularly as a component of blended fibers (described below), and because the treatment of the present invention can be effectively performed.

[0028] The non-polyester fibers are fibers other than the above-mentioned polyester fibers (for example, polyethylene terephthalate fibers), and may be staples (short fibers), filaments, or a combination thereof.

[0029] In one embodiment, the non-polyester fibers include natural fibers, specific examples of which include plant fibers such as cotton, hemp, and linen, and combinations thereof; animal fibers such as wool, cashmere, silk, and combinations thereof; and combinations thereof.

[0030] In one embodiment, the non-polyester fiber comprises at least one chemical fiber selected from the group consisting of polyamide fibers (e.g., nylon 6, nylon 66); polyvinyl alcohol fibers (e.g., vinylon); polyacrylonitrile fibers (e.g., Exlan, Cashmilon); polyvinyl chloride fibers (e.g., Teviron, Environ); polyolefin fibers (e.g., polypropylene fibers, polyethylene fibers); and polystyrene fibers.

[0031] In one embodiment, the non-polyester fibers include recycled fibers, which are fibers obtained by chemically treating natural cellulosic materials such as wood or pulp, specific examples of which include rayon and cupro, and combinations thereof.

[0032] In the present invention, the term "mixed fibers" refers to a group of fibers formed by mixing the above polyester fibers with non-polyester fibers (other than polyester fibers), and includes any of the following: blended fibers composed of the above polyester fibers and the above natural fibers; fibers composed of the above polyester fibers and the above chemical fibers (other than polyester fibers); fibers composed of the above polyester fibers and the above regenerated fibers; fibers composed of the above polyester fibers, natural fibers, and chemical fibers; fibers composed of the above polyester fibers, chemical fibers, and regenerated fibers; and fibers composed of the above polyester fibers, natural fibers, chemical fibers, and regenerated fibers. Blended fibers composed of the above polyester fibers and natural fibers are preferred because they are widely used in apparel products and can be efficiently separated, and blended fibers composed of the above polyester fibers and cotton fibers are more preferred.

[0033] The blending ratio (e.g., blending ratio) of polyester fiber and non-polyester fiber in the blended fiber is not particularly limited, and the polyester fiber is preferably contained in a proportion of 1% by mass to 99% by mass, more preferably 2% by mass to 98% by mass, and even more preferably 5% by mass to 95% by mass relative to the total mass (100% by mass) of the blended fiber. If the polyester fiber content in the blended fiber is less than 1% by mass, it may be difficult to efficiently proceed with the reaction described below. If the polyester fiber content in the blended fiber is more than 99% by mass, the reaction described below will proceed efficiently, but almost no solid components derived from the non-polyester fiber will remain in the resulting reaction mixture, making recovery difficult.

[0034] The method of the present invention is carried out on the above-mentioned mixed fiber, and specifically, a reaction mixture is first prepared by irradiating a mixture of the mixed fiber and alkylene glycol with microwaves at a temperature of 180°C to 250°C.

[0035] The alkylene glycol functions as a reaction solvent in the present invention. The alkylene glycol is preferably an alkylene glycol having 2 to 6 carbon atoms, and specific examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, polytetramethylene glycol, 1,4-cyclohexanediol, 1,4-benzenediol, and combinations thereof. Alkylene glycols having 2 to 4 carbon atoms (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, and combinations thereof) are preferred because they are highly versatile and the reaction with the polyester fibers proceeds more effectively, and ethylene glycol, propylene glycol, and combinations thereof are more preferred because they are more readily available.

[0036] The mixing ratio of the mixed fibers and alkylene glycol in the mixture is not particularly limited, but in order to efficiently promote the reaction between the polyester fibers and alkylene glycol in the mixture, the content of alkylene glycol is preferably 100 to 10,000 parts by volume, and more preferably 150 to 8,000 parts by volume, per 100 parts by mass of the mixed fibers. If the content of alkylene glycol is less than 100 parts by volume, the reaction between the polyester fibers and alkylene glycol in the resulting mixture may not proceed efficiently. If the content of alkylene glycol exceeds 10,000 parts by volume, the content of alkylene glycol becomes excessive relative to the components derived from the polyester fibers, and pretreatment such as concentration of the alkylene glycol is required in the recovery of the components derived from the polyester fibers, which may reduce industrial efficiency.

[0037] In the present invention, in order to increase the reactivity between the polyester fiber and the alkylene glycol, it is preferable to add an ester exchange reaction catalyst to the mixture.

[0038] In the present invention, the transesterification catalyst is a catalyst that promotes the transesterification reaction between the polyester fiber and alkylene glycol in the mixed fiber. Specific examples include acetate, calcium oxide, zinc sulfate, and combinations thereof. Specific examples of acetate include salts of acetic acid and divalent metals (e.g., zinc acetate, magnesium acetate, calcium acetate, manganese acetate, nickel acetate, iron acetate, cobalt acetate, and combinations thereof), and salts of acetic acid and fatty acids (e.g., propionic acid, octanoic acid, stearic acid, and combinations thereof). Because of their high reactivity and easy availability, acetate and calcium oxide, and combinations thereof, are preferred as transesterification catalysts, with acetate being more preferred.

[0039] The content of the transesterification catalyst in the mixture is preferably 0.001 to 30 parts by mass, and more preferably 0.01 to 20 parts by mass, relative to 100 parts by mass of the polyester fibers contained in the mixed fiber used. If the content of the transesterification catalyst is less than 0.001 part by mass, the reaction between the polyester fibers and the alkylene glycol in the resulting mixture may be slow. If the content of the transesterification catalyst exceeds 30 parts by mass, it may have an adverse effect on the separation and purification of the product (e.g., bis(2-hydroxyethyl) terephthalate (BHET)) described below, and may actually reduce industrial efficiency.

[0040] The mixture is irradiated with microwaves in a microwave reactor known to those skilled in the art.

[0041] In the present invention, the microwave reactor is a device that can generate microwaves preferably at an output of 100 W to 1000 W and is generally used in organic or inorganic synthesis. Such a microwave reactor can efficiently promote the reaction between the polyester fiber and alkylene glycol when the temperature of the mixture is set to 180° C. to 250° C., preferably 185° C. to 230° C., and more preferably 190° C. to 230° C.

[0042] The time for irradiating the mixture with microwaves is not particularly limited, and varies depending on the amount of mixed fiber used, the amount of polyester fiber contained in the mixed fiber (mixing ratio of polyester fiber to non-polyester fiber), etc., so it is not particularly limited and an appropriate time can be selected by a person skilled in the art.

[0043] By irradiating the mixture with microwaves, an ester exchange reaction between the polyester fibers in the mixed fibers and the alkylene glycol proceeds, and a reaction mixture can be obtained.

[0044] For example, when polyethylene terephthalate (PET) fibers are contained as polyester fibers in the mixed fibers, the PET is decomposed by the above transesterification reaction and converted into bis(2-hydroxyethyl) terephthalate (BHET).

[0045]

[0046] This BHET is a precursor of PET and can be easily regenerated into PET by chemical recycling after purification. In the present invention, this BHET can be present as a liquid component in the reaction mixture in a state where it is dissolved in alkylene glycol.

[0047] On the other hand, in the above reaction, the non-polyester fibers in the mixed fibers can be present as solid components in the reaction mixture while maintaining, for example, the state of the non-polyester fibers in their original state.

[0048] Next, in the present invention, the reaction mixture is separated into solid and liquid components.

[0049] The method for separating the reaction mixture into solid and liquid components is not particularly limited, but for example, filtration using a method known in the art or decantation after centrifugation can be employed.

[0050] In this manner, components derived from the polyester fibers (liquid components) and components derived from the non-polyester fibers (solid components) can be separated from a mixed fiber containing polyester fibers and non-polyester fibers.

[0051] Here, if polyethylene terephthalate (PET) fibers are contained as polyester fibers in the mixed fibers, the liquid component contains BHET decomposed from PET as described above in a dissolved state in alkylene glycol.

[0052] Therefore, in the present invention, a solvent (e.g., hot water or water) having a lower solubility than the alkylene glycol in BHET may be added to the liquid component to recrystallize BHET. The recrystallized BHET is separated, for example, by filtration, and washed and purified as necessary. The obtained BHET can then be easily regenerated into the original polyester fiber by, for example, melt polymerization again.

[0053] On the other hand, the liquid residue can be distilled by means known in the art to recover the alkylene glycol solvent, which can be reused by remixing with the mixed fibers to obtain the above-mentioned mixture.

[0054] In the present invention, since polyester fibers can be converted into the polyester precursors that constitute the fibers as described above, polyester fibers can be regenerated with fewer steps than conventional techniques, such as decomposing polyethylene terephthalate (PET) fibers into terephthalic acid, one of the starting materials. In this respect, the method of the present invention can be said to be industrially superior.

[0055] Furthermore, the solid component obtained through separation contains the non-polyester fibers contained in the mixed fiber remaining in almost the same state. This is because the non-polyester fibers are not particularly affected by the transesterification reaction between the polyester fibers contained in the mixed fiber and the alkylene glycol. As a result, the obtained solid component can be washed, bleached, etc., as needed, using means known to those skilled in the art, and the non-polyester fibers can finally be recovered.

[0056] The recovered non-polyester fibers may be used together with new non-polyester fibers to produce another apparel product, or may be mixed again (e.g., blended or mixed) with the above or newly prepared polyester fibers and used to produce another apparel product.

[0057] From the above, the treatment method of the present invention can be one solution for separating polyester fibers and non-polyester fibers from mixed fibers. Furthermore, it can eliminate or reduce the environmental impact after disposal of many apparel products using mixed fibers, which have traditionally been difficult to recycle.

[0058] (Mixed Fiber Treatment Apparatus) The mixed fiber treatment apparatus of the present invention will be described below with reference to the drawings.

[0059] FIG. 1 is a schematic diagram illustrating an example of a mixed fiber treatment device according to the present invention.

[0060] The mixed fiber treatment device (hereinafter, sometimes simply referred to as the “treatment device”) 100 shown in FIG. 1 includes a reaction vessel 110 , a microwave generating means 130 , and a separating means 150 .

[0061] The reaction vessel 110 is made of a material (e.g., glass) that can be irradiated with microwaves emitted by a microwave generating means 130 (described later) and contains a mixture 112 of mixed fibers containing polyester fibers and non-polyester fibers and alkylene glycol having 2 to 6 carbon atoms. For example, the reaction vessel 110 may have a shape similar to a three-neck flask. The size or capacity of the reaction vessel 110 is not particularly limited, and an appropriate size or capacity can be selected by a person skilled in the art depending on the desired amount of mixed fibers to be processed.

[0062] The reaction vessel 110 shown in Figure 1 includes an agitator blade 114 for agitating the mixture inside, and a shaft 116 and motor 118 connected to the agitator blade 114. The top of the reaction vessel 110 is usually sealed with a top lid 120, which is equipped with an openable inlet pipe 122 for supplying mixed fibers from the outside into the reaction vessel 110, a temperature sensor 124 for controlling the temperature of the mixture inside the reaction vessel 110, and a reflux pipe 126 for efficiently carrying out the reaction inside the reaction vessel 110. The top lid 120 is also equipped with a recovery pipe 190 for returning alkylene glycol contained in a recovery liquid (described later) to the reaction vessel 110.

[0063] 1 may be connected via a pipe 162 to a first preliminary tank 159 for introducing fresh alkylene glycol into the reaction tank 110. A predetermined amount of a transesterification catalyst may be added and dispersed in the first preliminary tank 159 together with the fresh alkylene glycol.

[0064] The microwave generating means 130 is provided to irradiate the mixture 112 of the mixed fiber and alkylene glycol with microwaves to obtain a reaction mixture. In the embodiment shown in FIG. 1 , the microwave generating means 130 is arranged to surround the reaction vessel 110. As the microwave generating means 130, microwave generators of various scales can be used, for example, depending on the amount of mixed fiber to be treated. Specific examples of the microwave generating means 130 include various microwave generators for home, laboratory, or industrial use.

[0065] In FIG. 1, the shaft 116 extending from the top lid 120 of the reaction vessel 110 to the outside, the inlet pipe 122, the temperature sensor 124, the reflux pipe 126, and the recovery pipe 190 are all arranged so as to pass through the microwave generating means 130 and extend to the outside.

[0066] The separating means 150 is used to separate the reaction mixture obtained by irradiating the mixture 112 of the mixed fibers and alkylene glycol in the reaction vessel 110 with microwaves into a solid component and a liquid component.

[0067] In the embodiment shown in FIG. 1 , the separation means 150 is disposed near the bottom of the reaction tank 110. When a valve 152 provided at the bottom of the reaction tank 110 is opened, the reaction mixture in the reaction tank 110 can be separated into solid components (mainly non-polyester fibers) and other liquid components via the separation means 150. The separation means 150 may be a known device such as filter paper or filter cloth. The separated solid components remain on the separation means 150 and can be easily removed by removing the top lid 120 of the reaction tank 110.

[0068] 1 illustrates an example in which the separation means 150 is disposed inside the reaction vessel 110, i.e., inside the microwave generation means 130, but the location of the separation means 150 is not particularly limited. For example, the fractionation means 150 may be provided in a storage tank (not shown) provided outside the reaction vessel 110 and the microwave generation means 130, and the reaction mixture in the reaction vessel 110 may be supplied to the storage tank to separate the solid component from the liquid component. In this case, since the separation means 150 is disposed outside the microwave generation means 130, a metallic separation means such as a metal filter may be used.

[0069] The processing apparatus 100 of the present invention shown in FIG.

[0070] The settling tank 160 contains the liquid component separated from the reaction mixture and serves to promote the formation of a precipitate. In Fig. 1, the settling tank 160 is disposed downstream of the pipe 154 connected to the bottom of the reaction tank 110, and by opening the valve 152, the liquid component separated by the separation means 150 can be contained inside.

[0071] 1 , the settling tank 160 is sealed with, for example, an openable second top lid 161, and is connected to a pipe 166 extending from a second reserve tank 164 that contains a medium such as water. The settling tank 160 may further be provided with a temperature adjustment means 168 for heating and / or cooling the liquid component contained therein. For example, in the embodiment shown in FIG. 1 , the temperature adjustment means 168, such as a heater or a cooling jacket, is provided around the settling tank 160.

[0072] The liquid component contained in the precipitation tank 160 is mixed with water fed from the second preliminary tank 164 as needed, and is further cooled by a temperature control means 168, thereby starting precipitation of components derived from the polyester fibers. For example, when the polyester fibers are polyethylene terephthalate fibers, bis(2-hydroxyethyl) terephthalate (BHET) crystallizes as described above, and precipitation starts.

[0073] Furthermore, in the treatment apparatus shown in FIG. 1 , a second separation means 170 is disposed near the bottom of the settling tank 160. The second separation means 170 may be a known means such as filter paper, filter cloth, or metal filter. When a valve 172 disposed at the bottom of the settling tank 160 is opened, the contents of the settling tank 160 can be separated via the second separation means 170 into a second solid component resulting from precipitation of BHET and the like and a second liquid component other than the solid component. The separated second solid component remains on the second separation means 170 and can be easily removed by removing the second top lid 162 of the settling tank 160.

[0074] The treatment device 100 of the present invention shown in FIG. 1 may also include a means 180 for storing a recovered liquid containing alkylene glycol (hereinafter, sometimes referred to as a "recovered liquid storing means").

[0075] The recovered liquid storage means 180 serves to store the second liquid component obtained from the settling tank 160 via the second separation means 170. In Fig. 1 , the recovered liquid storage means 180 includes a recovery tank 182 and second heating means 184 surrounding the recovery tank 182. The recovery tank 182 is, for example, a sealable container, and the second heating means 184 has the form of, for example, a heater or a heating jacket, and can heat the second liquid component stored as the recovered liquid within the recovery tank 182.

[0076] In the embodiment shown in Fig. 1, when valve 172 is opened, the second liquid component in settling tank 160 passes through pipe 174 and is stored in recovery tank 182 in recovered liquid storage means 180. Then, by heating by second heating means 184 in recovered liquid storage means 180, the alkylene glycol contained in the second liquid component in recovery tank 182 can be extracted as a volatile component.

[0077] Specifically, for example, if the recovery tank 182 of the recovered liquid storage means 180 contains a substance (e.g., water) with a boiling point lower than that of alkylene glycol, when the second liquid component in the recovery tank 182 is heated by the second heating means 184, the substance with the low boiling point (e.g., water vapor) is generated as an initial volatile component. In this case, this initial volatile component is discharged to the outside from the pipe 193 via the three-way valve 192 provided downstream of the recovered liquid storage means 180. Thereafter, when the alkylene glycol contained in the second liquid component in the recovery tank 182 begins to volatilize, the three-way valve 192 is switched, and the volatilized alkylene glycol is discharged to the outside of the recovered liquid storage means 180 through the recovery pipe 190. Meanwhile, when the alkylene glycol volatilizes, residues of the catalyst used and / or by-products generated through the above reaction remain in the recovery tank 182 of the recovered liquid storage means 180. These can be discharged to the outside through a pipe 196 by opening a valve 195 provided at the bottom of the collection tank 182 .

[0078] Furthermore, in the present invention, the alkylene glycol discharged as a volatile component outside the recovered liquid storage means 180 can be returned to a liquid state in a condenser 198, which is provided as needed, and returned as is to the reaction tank 110 through the recovery pipe 190.

[0079] In this way, it is possible to separate the non-polyester fibers from the mixed fiber of polyester fibers and non-polyester fibers, and further separate the components derived from the polyester fibers as solid components. Furthermore, the alkylene glycol having 2 to 6 carbon atoms used in such separation can also be reused for the next treatment of the mixed fiber through distillation after the separation.

[0080] The treatment device of the present invention may have the form of either a relatively small-scale device capable of treatment on a laboratory scale, or a large-scale device capable of treating mixed fibers recovered from industrial waste or household recyclable waste on a plant scale.

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0082] Example 1: Recovery of cellulose and BHET from a white polo shirt sample. 100 mL of ethylene glycol (EG) was added to 10 g of a sample (54% cotton fiber, 46% PET fiber) collected from a white polo shirt. ZnAc was used as a transesterification catalyst. ２ 0.05 g of HCl was added to prepare a mixture. This mixture was placed in a glass container equipped with a reflux condenser and a thermometer and placed in a microwave reactor (μReactor EX, manufactured by Shikoku Keisoku Kogyo Co., Ltd.). The program was set to a heating rate of 10°C / min, a set temperature of 200°C, a microwave output of 50% duty, and a 10-second cycle. The reactor was stopped 7 minutes after the reaction solution began to boil (the boiling temperature of the reaction solution was approximately 190-194°C). The microwave output reached a maximum of approximately 550 W every 10 seconds over the 7 minutes. The reaction solution was cooled to approximately 100°C, and the solid component (fiber) was removed from the reaction solution. 150 mL of hot water at approximately 95°C was added to the reaction solution, stirred, and then the entire liquid was returned to the reaction solution. This allowed the reaction solution adhering to the fiber to be recovered. The reaction solution was then heated to approximately 95°C and stirred for several minutes. The mixture was then immediately filtered while still hot using a Kiriyama funnel to remove insoluble matter.

[0083] The filtrate was then left to stand at room temperature overnight or longer to precipitate crystals. These were collected by filtration, washed with water, and dried at 80°C to obtain 3.28 g of compound (Ec1). An optical microscope photograph of the obtained compound (Ec1) is shown in Figure 2. Compound (Ec1) was in the form of crystals.

[0084] Furthermore, the obtained compound (Ec1) １ The H-NMR spectrum was measured using an NMR apparatus (ECS400 manufactured by JEOL Ltd.) and the results obtained were as follows: 1 H-NMR (400MHz, DMSO-D6) δ8.09(s,4H), 4.94(tJ=5.7Hz, 2H), 4.28(t,J=4.8Hz, 4H), 3.68(q, J=5.0Hz, 4H).

[0085] The obtained compound (Ec1) １ The H-NMR spectrum was measured using pure bis(2-hydroxyethyl) terephthalate (BHET) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). １ When compared with the H-NMR spectrum, the peaks in both spectra were almost identical, confirming that the crystalline compound (Ec1) obtained above was BHET.

[0086] On the other hand, the solid component (fiber) obtained above was further washed with hot water, then washed with ethanol, and dried at 80 ° C. to obtain 4.97 g of solid component (fiber) (Es1). IR spectrum of this was measured using a Fourier transform infrared spectrometer (iS5, ATR iD5 manufactured by Thermo Fisher Scientific). The analysis conditions were as follows: (FTIR) Crystal: Diamond Incident angle: 45 degrees Number of reflections: 1.0 Refractive index of sample: 1.50

[0087] The results obtained are shown in Figure 3. As shown in Figure 3, when the IR spectrum of the solid component (fiber) (Es1) was compared with the IR spectrum of pure cellulose (manufactured by SIGMA-ALDRICH), the peaks of both spectra were found to be almost identical. On the other hand, as shown in Figure 3, when the IR spectrum of the solid component (fiber) (Es1) was compared with the IR spectrum of pure PET (manufactured by SIGMA-ALDRICH), the peaks of both spectra did not match. This confirmed that the solid component (fiber) (Es1) obtained above was composed of cellulose.

[0088] The yield of the obtained solid component (fiber) (Es1) (cellulose) was 92.0%, and the yield of BHET (compound (Ec1)) recovered from the obtained liquid component was 71.3%. The results are shown in Tables 1 and 2.

[0089] The solid component (fiber) (Es1) obtained above and the untreated white polo shirt sample used were observed under a scanning electron microscope (SU3500 manufactured by Hitachi High-Technologies Corporation). The results are shown in Figure 4.

[0090] As shown in Figure 4, the solid component (fiber) (Es1) obtained above (Figure 4(a)) (Figure 4(a)) was not observed to have any significant erosion on its surface, and it maintained a sufficient fibrous form, as is clear from a comparison with the mixed fiber in the sample before treatment (Figure 4(b)). Furthermore, since the solid component (fiber) (Es1) is mostly composed of cellulose as described above, it was found to have maintained the state of cotton fiber.

[0091] Example 2: Recovery of cellulose and BHET from white polo shirt samples. Zinc acetate (ZnAc ２A white polo shirt sample was treated in the same manner as in Example 1, except that the amount of cellulose added was changed to 0.1 g, the program temperature was set to 195°C, the boiling temperature was maintained for 4 minutes, and the amount of hot water added was changed to less than 100 mL. This resulted in 4.94 g of solid cellulose and 2.12 g of crystals (BHET) recovered from the liquid. The cellulose yield was 91.4%, and the BHET yield was 46.1%. The boiling temperature of the reaction solution was approximately 190-194°C, and the microwave power reached a maximum of approximately 500 W every 10 seconds for 4 minutes. The results are shown in Tables 1 and 2.

[0092] Example 3: Recovery of cellulose and BHET from a white polo shirt sample. Magnesium acetate tetrahydrate (MgAc) was used instead of zinc acetate as the transesterification catalyst. ２ ・4H ２ A white polo shirt sample was treated in the same manner as in Example 1, except that 0.1 g of cellulose was used, the amount of EG added was changed to 58.2 mL, and the amount of hot water added was changed to 90 mL. This resulted in 4.92 g of solid cellulose and 2.67 g of crystals (BHET) recovered from the liquid. The cellulose yield was 91.1%, and the BHET yield was 58.1%. The boiling temperature of the reaction solution was approximately 190-195°C, and the microwave power reached a maximum of approximately 550 W every 10 seconds over a 7-minute period. The results are shown in Tables 1 and 2.

[0093] Example 4: Recovery of cellulose and BHET from a white polo shirt sample. Calcium acetate hydrate (CaAc) was used instead of zinc acetate as the transesterification catalyst. ２ ・H ２ A white polo shirt sample was treated in the same manner as in Example 1, except that 0.05 g of cellulose was used, yielding 4.95 g of solid component (cellulose) and 2.18 g of crystals (BHET) recovered from the liquid component. The cellulose yield was 91.6%, and the BHET yield was 47.5%. The boiling temperature of the reaction solution was approximately 190-195°C, and the microwave power reached a maximum of approximately 550 W every 10 seconds for 7 minutes. The results are shown in Tables 1 and 2.

[0094] Example 5: Recovery of cellulose and BHET from a white polo shirt sample A white polo shirt sample was treated in the same manner as in Example 1, except that the transesterification catalyst (zinc acetate) was not added and the boiling temperature was maintained for 60 minutes, yielding 4.88 g of a solid component (cellulose) and 3.15 g of crystals (BHET) recovered from the liquid component. The cellulose yield was 90.5%, and the BHET yield was 68.5%. The boiling temperature of the reaction solution was approximately 190-194°C, and the microwave power output for 60 minutes reached a maximum of approximately 550 W every 10 seconds. The results are shown in Tables 1 and 2.

[0095] (Example 6: Recovery of cellulose and BHET from work gloves) Work gloves (20% cotton fiber, 80% PET fiber) were used instead of white polo shirts, and zinc acetate (ZnAc) ２ The procedure was the same as in Example 1, except that the amount of cellulose added was changed to 0.1 g and the amount of hot water added was changed to just under 100 mL, yielding 1.69 g of a solid component (cellulose) and 6.29 g of crystals (BHET) recovered from the liquid component. The cellulose yield was 84.3%, and the BHET yield was 78.6%. The boiling temperature of the reaction solution was approximately 190-194°C, and the microwave output reached a maximum of approximately 550 W every 10 seconds over a 7-minute period. The results are shown in Tables 1 and 2.

[0096] Comparative Example 1: Recovery of cellulose and BHET from a white polo shirt sample Zinc acetate (ZnAc ２ A white polo shirt sample was treated in the same manner as in Example 1 to obtain a solid component and a liquid component, except that the amount of cellulose added was changed to 0.1 g, the program temperature was set to 180°C, the boiling temperature was maintained for 30 minutes, the microwave output period was changed to 5 seconds, and the amount of hot water added was changed to just under 100 mL. The total mass of the obtained solid component was 5.60 g, of which the cellulose content was 4.40 g (yield 81.0%). Meanwhile, the content of crystals (BHET) recovered from the liquid component was 1.95 g (yield 42.3%). The microwave output reached a maximum of approximately 150 W every 5 seconds over 30 minutes. The results are shown in Tables 1 and 2.

[0097] Comparative Example 2: Recovery of Cellulose and BHET from a White Polo Shirt Sample A white polo shirt sample was treated in the same manner as in Example 1 to obtain a solid component and a liquid component, except that the program temperature was set to 195°C and the amount of hot water added was changed to just under 100 mL. The total mass of the obtained solid component was 5.40 g, of which the cellulose content was 4.80 g (yield 88.6%). Meanwhile, the content of crystals (BHET) recovered from the liquid component was 2.11 g (yield 45.9%). The boiling temperature of the reaction solution was approximately 190-194°C, and the microwave output reached a maximum of approximately 350-440 W every 10 seconds for 7 minutes. The results are shown in Tables 1 and 2.

[0098] Comparative Example 3: Recovery of cellulose and BHET from a white polo shirt sample Zinc acetate (ZnAc ２ A white polo shirt sample was treated in the same manner as in Example 1 to obtain a solid component and a liquid component, except that the amount of cellulose added was changed to 0.1 g, an oil bath was used instead of a microwave reactor, the oil temperature was set to 200°C, and the boiling time was set to 60 minutes. The total mass of the obtained solid component was 5.08 g, of which the cellulose content was 4.50 g (yield 83.3%). Meanwhile, the content of crystals (BHET) recovered from the liquid component was 2.89 g (yield 62.9%). The heating rate of the reaction solution was 3 to 5°C / min, and the boiling temperature was approximately 190 to 193°C. The results are shown in Tables 1 and 2.

[0099] (Reference Example 1: Recovery of cellulose and BHET from a work glove (100% cotton) sample) A solid component and a liquid component were obtained by treating in the same manner as in Example 1, except that work gloves (100% cotton) were used instead of white polo shirts. The cellulose content of the obtained solid component was 9.52 g (yield 95.2%). On the other hand, no crystals were obtained from the liquid component. The boiling temperature of the reaction liquid was approximately 190°C, and the microwave output reached a maximum of approximately 550 W every 10 seconds for 7 minutes. The results are shown in Tables 1 and 2.

[0100]

[0101]

[0102] As shown in Tables 1 and 2, by irradiating the mixture with microwaves under the conditions described in Examples 1 to 6, the component derived from the cotton fiber (cellulose) and the component derived from the PET fiber (bis(2-hydroxyethyl) terephthalate (BHET)) contained in the blended sample were separated and recovered in high yields into solid and liquid components, respectively.

[0103] (Example 7: Treatment of a work glove sample and recovery of ethylene glycol and BHET) 100 mL of ethylene glycol was added to 10 g of a sample (20% cotton fiber, 80% PET fiber) collected from a work glove, and zinc acetate (ZnAc) was used as a transesterification catalyst. ２ ) was added to prepare a mixture. This mixture was placed in a glass container equipped with a reflux condenser and a thermometer and placed in a microwave reactor (μReactor EX, manufactured by Shikoku Keisoku Kogyo Co., Ltd.). The reactor was started with a heating rate of 10°C / min, a set temperature of 200°C, a microwave output of 50% duty, and a cycle of 10 seconds. The reactor was stopped 10 minutes after the reaction solution began to boil. The microwave output reached a maximum of approximately 550 W every 10 seconds over the 10-minute period. The reaction solution was cooled to approximately 100°C, and only the solid component (fiber) was extracted from the reaction solution. This yielded a reaction solution from which the solid component (fiber) had been separated. The same procedure was repeated to obtain 203.4 g of a reaction solution from which the solid component (fiber) had been separated, equivalent to two batches.

[0104] This reaction solution was distilled at 124°C under a reduced pressure of 5 kPa to recover 2.8 g of a first fraction. The reaction solution was then distilled at 126°C to recover 179.5 g of a main fraction (recovery rate: 88.2%). After distillation, 19.8 g of distillation residue was obtained.

[0105] Next, the obtained initial and main fractions of CDCl ３ During １ The H-NMR spectrum was measured using an NMR device (ECS400 manufactured by JEOL Ltd.) and the obtained spectrum is shown in FIG.

[0106] As shown in FIG. 5, a peak corresponding to ethylene glycol used in this example was confirmed in both the initial fraction and the main fraction.

[0107] On the other hand, the distillation residue obtained above was washed with water, filtered, and dried at 70° C. for 2 days to obtain 14.7 g of a gray solid. As a result, the recovery rate of ethylene glycol contained in the reaction solution by distillation was approximately 95.1%.

[0108] This gray solid was dissolved in deuterated DMSO, １ The H-NMR spectrum was measured using an NMR device (ECS400 manufactured by JEOL Ltd.). The obtained spectrum was analyzed by CDCl ３ During １ H-NMR spectrum and the determination of reagent grade bis(2-hydroxyethyl) terephthalate (BHET) (Fujifilm Wako Pure Chemical Industries, Ltd.) in deuterated DMSO. １ The H-NMR spectrum is shown in FIG.

[0109] As shown in FIG. 6, the peak of the gray solid obtained as the distillation residue resembled that of reagent-grade BHET, indicating that the gray solid was a mixture of BHET and impurities.

[0110] (Example 8: Treatment of a work glove sample using recycled ethylene glycol) To 10 g of a sample (20% cotton fiber, 80% PET fiber) collected from a work glove, 100 mL of ethylene glycol (main fraction) recovered in Example 7 was added without purification, and zinc acetate (ZnAc) was used as a transesterification catalyst. ２ ) was added to prepare a mixture.

[0111] Except for using this mixture, microwaves were applied to the mixture in the same manner as in Example 1, the solid component (fibers) was recovered from the reaction solution, and the residue was washed and crystallized to recover BHET crystals. The recovery rates of the obtained solid component (fibers) and BHET per 10 g of work gloves sample used are shown in Table 3.

[0112] Next, the IR spectrum of the solid component (fiber) (the solid component (fiber) obtained by reusing the recovered ethylene glycol) was measured in the same manner as in Example 1. The results are shown in Figure 7 as Reference Example 2, along with the IR spectrum of the work gloves themselves (work gloves sample) used above, measured in the same manner as in Example 1.

[0113] On the other hand, the IR spectrum of the BHET crystals (BHET crystals obtained by reusing recovered ethylene glycol) was measured using a Fourier transform infrared spectrometer (iS5, ATR iD5 manufactured by Thermo Fisher Scientific) under the following analytical conditions: (FTIR) Crystal: Diamond Incident angle: 45 degrees Number of reflections: 1.0 Refractive index of sample: 1.50

[0114] The results are shown in FIG. 8 together with the IR spectrum measured for the BHET crystals obtained in Example 7 (BHET obtained by distilling the reaction solution).

[0115] (Comparative Example 4: Treatment of a work glove sample with ethylene glycol (fresh solution)) A solid component (fiber) was recovered in the same manner as in Example 8, except that 100 mL of commercially available ethylene glycol (fresh solution) was used instead of the ethylene glycol (main fraction) recovered in Example 7. The residue was washed and crystallized to recover BHET crystals. The recovery rates of the obtained solid component (fiber) and BHET relative to the work glove sample (10 g) used are shown in Table 3.

[0116] Next, the IR spectrum of the solid component (fibers) (solid component (fibers) obtained using ethylene glycol (fresh solution)) was measured in the same manner as in Example 1. The results are shown in FIG. 7. Furthermore, the IR spectrum of the BHET crystals (BHET obtained using ethylene glycol (fresh solution)) was measured in the same manner as in Example 8. The results are shown in FIG. 8.

[0117]

[0118] As shown in Table 3, the recovery rates of the solid components (fibers) and BHET obtained from the work glove sample by reusing the ethylene glycol recovered in Example 7 (Example 8) were not substantially different from the recovery rates of the solid components (fibers) and BHET obtained by using a fresh ethylene glycol solution (Comparative Example 4). This shows that the ethylene glycol used and recovered by the method of the present invention can be fully reused for further treatment of mixed fibers containing polyester fibers and non-polyester fibers.

[0119] As shown in FIG. 7, the IR spectra of the solid component (fiber) obtained from the work glove sample by reusing the recovered ethylene glycol (Example 8) and the solid component (fiber) obtained using a fresh ethylene glycol solution (Comparative Example 4) show that the 1700 cm IR spectrum that appeared in the IR spectrum of the untreated work glove sample (Reference Example 1) itself is not present. －１ The characteristic peaks in the vicinity are lost, indicating that the solid components obtained in Example 8 and Comparative Example 4 are composed of fibers (mainly cotton fibers) different from those of the work gloves sample, which is a blend of polyester fibers and cotton fibers. Furthermore, as is clear from Figure 7, the IR spectra obtained in Example 8 and Comparative Example 4 have similar peaks, indicating that both can be effectively used to treat the work gloves sample, regardless of whether the ethylene glycol used was recovered or new liquid.

[0120] 8, the IR spectra of BHET obtained from the work glove sample by reusing recovered ethylene glycol (Example 8), BHET obtained using fresh ethylene glycol (Comparative Example 4), and BHET recovered from the distillation residue of the reaction solution obtained in Example 7 after washing with water (Example 7) all had similar peaks. This indicates that there is no substantial difference in the obtained substances regardless of whether the ethylene glycol used was recovered or fresh, or whether the residue was washed with water or not.

[0121] The present invention is useful in technical fields related to the textile industry, such as the textile industry (textile manufacturing) field and the clothing and personal item manufacturing field (apparel manufacturing) field.

[0122] REFERENCE SIGNS LIST 100 Mixed fiber treatment device 110 Reaction tank 112 Mixture 114 Stirring blade 116 Shaft 118 Motor 120 Top cover 122 Inlet pipe 124 Temperature sensor 126 Reflux pipe 130 Microwave generating means 150 Separation means 159 First reserve tank 160 Settling tank 161 Second top cover 164 Second reserve tank 168 Temperature adjusting means 170 Second separation means 180 Recovered liquid storage means 182 Recovery tank 184 Second heating means 190 Recovery pipe 198 Condenser

Claims

1. A method for treating a mixed fiber containing polyester fibers and non-polyester fibers, comprising the steps of: irradiating a mixture of the mixed fiber and an alkylene glycol having 2 to 6 carbon atoms with microwaves at a temperature of 180°C to 250°C to obtain a reaction mixture; and separating the reaction mixture into a solid component and a liquid component.

2. The method of claim 1, wherein the mixture contains a transesterification catalyst.

3. The method of claim 2, wherein the transesterification catalyst is an acetate salt.

4. The method of claim 1, wherein the alkylene glycol is ethylene glycol.

5. The method of claim 1, wherein the polyester fibers are terephthalate-based fibers.

6. The method of claim 5, wherein the terephthalate-based fiber is at least one fiber selected from the group consisting of polyethylene terephthalate (PET) fiber, polybutylene terephthalate (PBT) fiber, and polytrimethylene terephthalate (PTT) fiber.

7. The method of claim 5, wherein said terephthalate-based fibers are polyethylene terephthalate (PET) fibers.

8. The method of claim 7, further comprising the step of recovering bis(2-hydroxyethyl) terephthalate (BHET) from the liquid component by recrystallization.

9. The method of claim 1, wherein the non-polyester fibers comprise natural fibers.

10. A treatment device for a mixed fiber containing polyester fibers and non-polyester fibers, comprising: a reaction vessel containing a mixture of the mixed fiber and an alkylene glycol having 2 to 6 carbon atoms; microwave generating means for irradiating the mixture with microwaves to obtain a reaction mixture; and means for separating the reaction mixture into a solid component and a liquid component.

11. The processing apparatus of claim 10, further comprising a settling tank for receiving the liquid component separated from the reaction mixture and promoting the formation of a precipitate.

12. The treatment device according to claim 11, further comprising means for separating the precipitate from the settling tank and receiving a recovered liquid containing the alkylene glycol.

13. The treatment device according to claim 12, further comprising means for returning the alkylene glycol contained in the recovered liquid to the reaction vessel.

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