Method for recovering and recycling disperse dyes from colored polymer waste having ester functional group

Abstract

The present invention relates to a method for recovering and recycling disperse dyes from colored polymer wastes having an ester functional group and, more specifically, to a method for recovering and recycling disperse dyes from colored polymer wastes having an ester functional group, wherein the disperse dyes are extracted by color from the polymer wastes having an ester functional group by using a first compound, and the disperse dyes extracted by color are colored on polymer fabrics having an ester functional group.

Description

Method for recovering and recycling disperse dyes from colored polymer wastes having ester functional groups

[0001] The present invention relates to a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group, and more particularly, to a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group, which comprises recovering a disperse dye from a polymer waste having an ester functional group by separating and recovering the dye according to the color of the dye, and dyeing a polymer having an ester functional group using the disperse dye recovered according to the color.

[0002] The clothing industry accounts for 10% of global greenhouse gas emissions. Meanwhile, global clothing production continues to increase annually, and the majority of manufactured clothing is incinerated or disposed of in nature, threatening the environment. Synthetic fibers, which account for over 60% of textile production due to their low cost and durability, are identified as a major cause of serious environmental pollution because they do not decompose as readily as plastics when disposed of.

[0003] Polymer waste, especially textile waste, is often mixed with various materials and colors without separate collection methods. Therefore, sorting by material and color is essential for recycling. This process is often performed manually or categorized by material specific gravity, resulting in inefficient sorting. Furthermore, even after sorting by material and color, various foreign substances (such as dyes) are often still present, limiting physical and chemical recycling.

[0004] In modern times, the accelerating cycle of fashion and consumption in clothing has led to the widespread adoption of cheap, mass-produced clothing (fast fashion), which has led to rapid growth in the production and consumption of synthetic fibers. Polyester, in particular, accounts for a significant portion of global textile production, reaching 60%. Disperse dyes, used to color polyester fibers, account for over 50% of total dye production.

[0005] Disperse dyes are mainly used for dyeing hydrophobic polymers such as polyester and acetate by dispersing them in aqueous solutions. Structurally, disperse dyes are broadly classified into anthraquinone, methine, nitrodiphenylamine, and azo dyes. Since they do not contain hydrophilic groups in their structures, they have the characteristic of not being uniformly dispersed in water during the dyeing process using water. Therefore, currently commercially available disperse dyes are mixed with about 50% or more of a dispersant to improve dispersion efficiency and dye bath stability.

[0006] Disperse dyes, which may be present in post-consumer waste fibers, exist in a dyed form with polymer structures that can exhibit high binding affinity through physical interactions. They can have complex chemical structures that produce a variety of colors depending on the chromophores and auxochromes. These dyes are designed to remain intact under various everyday conditions, such as washing, friction, and sunlight, and they also have a high affinity for small compounds produced by the breakdown of the fiber's polymer structure. Therefore, complete separation from the reaction products after the depolymerization process for chemical recycling of waste fibers is difficult, lowering product quality. Therefore, it is desirable to remove disperse dyes in advance during the recycling process of polymer waste containing dyes.

[0007] Because these disperse dyes exist in complex form with the polymer waste matrix, they are difficult to separate or remove from fibers through simple contact with water or organic solvents. Most are simply discarded into the environment or incinerated along with the waste fibers. Most dyes are highly harmful to the human body, and dyes contained in environmentally unfriendly waste clothing contribute to various water and air pollution issues.

[0008] The present invention relates to a method for separating and recycling disperse dyes from colored polymer waste having an ester functional group, and proposes a new method capable of separating polymers having an ester functional group from waste containing polymers having an ester functional group and other polymers, and simultaneously recovering and recycling disperse dyes by color.

[0009] As a prior art, Korean Patent Publication No. KR 10-2522806 B1 discloses a technology regarding an extractant that is used to extract foreign substances that express color from a colored polymer resin having an ester functional group and then used as is for depolymerization of the colored polymer resin having an ester functional group without separation, and U.S. Patent Publication No. US 2015-0059103 A1 discloses a technology for removing a dye from a polymer having an ester functional group using paraxylene, an aromatic compound, as an extractant, and Japanese Patent Publication JP 6659919 B2 discloses a technology for removing a dye by bringing an extractant containing 90% or more by weight of a glycol monoether having 8 to 15 carbon atoms into contact with polyester. However, the prior art technologies including the above-mentioned prior art documents have not yet disclosed an effective method for recovering disperse dyes by color from colored polymer waste having an ester functional group, recycling the recovered disperse dyes, and dyeing the recovered disperse dyes by color on polymer fibers having an ester functional group.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Korean Patent Publication KR 10-2522806 B1 (Registration Date: April 13, 2023)

[0013] (Patent Document 2) United States Patent Publication No. US 2015-0059103 A1 (Published on March 5, 2015)

[0014] (Patent Document 3) Japanese Patent Publication JP 6659919 B2 (registration date: February 10, 2020)

[0015] The present invention was created to solve the above-mentioned problem, and its purpose is to provide a method for recovering and recycling disperse dyes from colored polymer waste having an ester functional group, by classifying colored polymer waste having an ester functional group by color and separating and extracting disperse dyes from the polymer.

[0016] In addition, the present invention aims to provide a method for effectively dyeing a polymer having an ester functional group using a disperse dye.

[0017] In addition, the present invention can be utilized to recover disperse dyes by color from colored polymer waste having an ester functional group, and to redye a material composed of a polymer having an ester functional group using each dye recovered as a result.

[0018] In addition, the dye mixture recovered by color can effectively dye colored polymer waste having an ester functional group under non-aqueous conditions or under conditions in which a very small amount of water of 10% or less by weight is added to a dye bath, unlike conventional aqueous dyeing methods in which an excessive amount of water is used, and the purpose thereof is to provide a method for recovering and recycling disperse dyes from colored polymer waste having an ester functional group.

[0019] In order to solve the above problem, the present invention provides a method for recovering a disperse dye from colored polymer waste having an ester functional group, comprising the steps of: a) separating colored polymer waste having an ester functional group by color; and b) contacting the colored polymer waste having an ester functional group separated by color through step a) with a first compound so that a disperse dye in the colored polymer waste is eluted into the first compound; wherein the first compound comprises a monocyclic aromatic compound substituted with at least one methoxy or ethoxy functional group.

[0020] In one embodiment of the present invention, the step a) may include: a-1) cutting a colored polymer waste having an ester functional group into a predetermined size; a-2) measuring a color value of the polymer waste piece having an ester functional group cut in the step a-1); and a-3) classifying the polymer waste piece having an ester functional group by disperse dye color based on the color value of the polymer waste piece having an ester functional group measured in the step a-2) and a color value range set for each disperse dye color.

[0021] In one embodiment of the present invention, step b) may be characterized by contacting the polymer waste having an ester functional group separated by color through step a) with the first compound at a temperature range of 70°C to 200°C to extract a color-specific disperse dye.

[0022] In addition, the present invention provides a method for dyeing a polymer having an ester functional group, comprising the steps of: i) heating a mixed dye solution containing a first compound, a second compound, and a disperse dye to a predetermined temperature and bringing it into contact with a polymer having an ester functional group; ii) lowering the temperature of the mixed dye solution so that the disperse dye is fixed within a chain of the polymer; wherein the first compound is a monocyclic aromatic compound substituted with at least one methoxy or ethoxy functional group, and the second compound is at least one of a polyhydric alcohol having two or more water or alcohol functional groups.

[0023] In the dyeing method of the present invention, the polyhydric alcohol may have 2 to 6 carbon atoms, and the temperature of the mixed dye solution in step i) may be 90°C to 159°C, and the temperature of the mixed dye solution in step ii) may be lowered to a temperature below 70°C.

[0024] In one embodiment of the dyeing method of the present invention, the disperse dye in step i) may be a regenerated disperse dye recovered from a colored polymer, and the regenerated disperse dye may be obtained according to the method for recovering a disperse dye of the present invention.

[0025] In addition, the present invention provides a method for recycling a disperse dye contained in colored polymer waste having an ester functional group, the method comprising: a) separating colored polymer waste having an ester functional group by color; b) contacting the colored polymer waste having an ester functional group separated by color through step a) with a first compound to elute a disperse dye contained in the colored polymer waste into the first compound; c) adding a second compound to the first compound solution from which the disperse dye obtained in step b) has been eluted to obtain a mixed dye solution; and d) contacting the mixed dye solution with a polymer having an ester functional group to dye the polymer having an ester functional group; wherein the first compound is a monocyclic aromatic compound substituted with at least one methoxy or ethoxy functional group, and the second compound is at least one of water or a polyhydric alcohol having two or more alcohol functional groups.

[0026] In the method for recycling a disperse dye of the present invention, the step a) may include: a-1) cutting a colored polymer waste having an ester functional group into a predetermined size; a-2) measuring a color value of the polymer waste pieces having an ester functional group cut in the step a-1); and a-3) classifying the polymer waste pieces having an ester functional group by color based on the color value of the polymer waste pieces having an ester functional group measured in the step a-2) and a color value range set for each color of the disperse dye; and the polyhydric alcohol may be characterized in that it has 2 to 6 carbon atoms.

[0027] The present invention has the effect of recovering disperse dyes by color from colored polymer waste having ester functional groups by classifying colored polymer waste having ester functional groups in which various colors are mixed by color and extracting disperse dyes from the waste classified by color.

[0028] In addition, the present invention has the effect of selectively extracting only the disperse dye dyed on a polymer having an ester functional group in recovering the disperse dye, thereby separating only the polymer having an ester functional group from waste mixed with other polymers.

[0029] Furthermore, the dyeing method according to the present invention utilizes a disperse dye on a polymer having an ester functional group, and can be used under non-aqueous conditions that do not use water or conditions in which a small amount of water is applied as an additive. Furthermore, it can effectively dye without using a dispersant. Therefore, it has the advantage of significantly reducing the excessive amount of dyeing wastewater and excessive energy used in dyeing compared to conventional dyeing processes.

[0030] In addition, the present invention, in the process of dyeing a polymer having an ester functional group by recycling a disperse dye recovered from colored polymer waste having an ester functional group, can use the organic solvent used in recovering the disperse dye from the colored polymer waste without separation, and since the organic solvent is composed of compounds having a boiling point higher than the temperature at which dyeing occurs, dyeing can be performed even at atmospheric pressure. Therefore, the recycling or re-dyeing process of the recovered disperse dye can be implemented with very simple equipment, and the dyeing process is also very simple, so there is an effect of further improving economic efficiency.

[0031] FIG. 1 is a conceptual diagram illustrating a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group according to one embodiment of the present invention.

[0032] FIG. 2 is an exemplary liquid-liquid phase equilibrium diagram showing the phase boundary regions of a first compound and a second compound that can be used in dyeing a polymer fiber having an ester functional group according to one embodiment of the present invention as a function of their composition and temperature.

[0033] Figure 3 shows the results of nuclear magnetic resonance spectroscopy (NMR) measurements for each of the recycled dye and the pure dye that was not used for dyeing after separating only the dyed product with an azo-based disperse dye (CI Disperse Red 1) from the colored waste fiber mixture and applying an extractant. 1 It shows the H NMR spectrum.

[0034] Figure 4 shows the results of nuclear magnetic resonance spectroscopy (NMR) measurements for each of the recycled dye and the pure dye that was not used for dyeing after separating only the dyed product with an azo-based disperse dye (CI Disperse Red 1) from the colored waste fiber mixture and applying an extractant. 13 It shows the C NMR spectrum.

[0035] Figure 5 shows the results of nuclear magnetic resonance spectroscopy (NMR) measurements for each of the recycled dye and the pure dye that was not used for dyeing after separating only the dyed product with anthraquinone-based disperse dye (CI Disperse Red 9) from the colored waste fiber mixture and applying an extractant. 1 It shows the H NMR spectrum.

[0036] Figure 6 shows the results of nuclear magnetic resonance spectroscopy (NMR) measurements for each of the recycled dye and the pure dye that was not used for dyeing after separating only the dyed product with anthraquinone-based disperse dye (CI Disperse Red 9) from the colored waste fiber mixture and applying an extractant. 13 It shows the C NMR spectrum.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In general, the nomenclature used herein is well known and commonly used in the art.

[0038] Throughout this specification, whenever a part is said to “include” a component, this means that it may include other components, but not to the exclusion of other components, unless otherwise stated.

[0039] The present invention relates to a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group, characterized in that the disperse dye is extracted by color from the polymer waste having an ester functional group using a first compound, and the disperse dye extracted by color is dyed into a polymer having an ester functional group using a mixture of the first compound and the second compound.

[0040] In the present invention, the polymer having an ester functional group may be a polymer formed by polycondensation of a dicarboxylic acid and a dialcohol, wherein the dicarboxylic acid is selected from the group consisting of terephthalic acid, naphthalene dicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, trimellitic acid, pyromellitic acid, and combinations thereof, and the dialcohol is selected from the group consisting of ethylene glycol, trimethylene glycol, 1,2-propanediol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, decanemethylene glycol, dodecamethylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, Selected from the group consisting of tetrapropylene glycol, polypropylene glycol, di(tetramethylene) glycol, tri(tetramethylene) glycol, polytetramethylene glycol, pentaerythritol, 2,2-bis(4-β-hydroxyethoxyphenyl)propane and combinations thereof.

[0041] For example, the polymer having the ester functionality may be selected from polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyglycolide or polyglycolic acid (PGA), 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), Vectran, and combinations thereof.

[0042] In addition, the polymer waste having the ester functional group may be in various forms, for example, staple fibers, filaments, or a mixture thereof used for clothing or industrial purposes, and may be in the form of yarn, irregular shapes, or fabric.

[0043] In addition, in the present invention, the polymer waste having an ester functional group may be in the form of a single or mixed resin, for example, a plastic material such as polyethylene, high-density polyethylene, low-density polyethylene, polypropylene, polystyrene, polyvinyl chloride, etc., or a mixed polymer resin of a polymer having an ester functional group and one or more of cotton, hemp, wool, rayon, acetate, acrylic, nylon, polyurethane, etc., additionally included, and the other polymers mentioned above. For reference, the other polymers mixed with the polymer having an ester functional group listed as an example above are merely examples and are not limited to those listed above.

[0044] Hereinafter, a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group according to one embodiment of the present invention will be described in detail with reference to the attached drawings.

[0045] FIG. 1 is a conceptual diagram illustrating a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group according to one embodiment of the present invention.

[0046] As illustrated herein, a method for recovering a disperse dye from colored polymer waste having an ester functional group according to the present invention comprises the steps of: a) separating colored polymer waste having an ester functional group by color; b) contacting the colored polymer waste having an ester functional group separated by color through step a) with a first compound to elute the color-specific disperse dye as the first compound; and c) separating the polymer waste from the first compound solution from which the disperse dye has been eluted; wherein the first compound is characterized in that it includes at least one monocyclic aromatic compound substituted with at least one alkoxy functional group having 1 to 2 carbon atoms, i.e., at least one methoxy or ethoxy functional group.

[0047] The above step a) is a step of separating polymer waste by color. At this time, the method of separating by color mainly measures color values ​​using an optical method and compares them with a predetermined color value range to separate polymer waste by the color value range. When setting the color value range, the color values ​​used may use color values ​​by at least one color system among HCV, RGB, HEX, HSL, HSV, HWB, Lab, CMYK, LCH, XYZ, OKLAB, OKLCH, RGBA, and HSLA.

[0048] In the present invention, since the first compound has the ability to extract disperse dyes only from polymers having an ester functional group, it has the additional effect of being able to classify polymers having an ester functional group and other polymers in mixed polymer waste by classifying waste pieces with remaining color and colorless waste pieces through step b), and at this time, when the first compound is brought into contact with colored polymer waste, if colorless waste pieces are included, it is impossible to distinguish whether the colorless waste pieces are polymers having an ester functional group or other polymers, so in order to prevent this, the colorless waste can be separated separately in step a).

[0049] In addition, in the method for recovering a disperse dye from colored polymer waste having an ester functional group according to the present invention, the step a) includes: a-1) cutting the polymer waste having an ester functional group into a predetermined size; a-2) measuring the color value of the polymer waste piece having an ester functional group cut in the step a-1); and a-3) classifying the polymer waste piece having an ester functional group by disperse dye color based on the color value range set for each disperse dye color of the polymer waste piece having an ester functional group measured in the step a-2).

[0050] The above step a-1) is a step of cutting the polymer waste into small pieces. This step is to make it easy to classify the polymer waste into a single color. In the case of polymer waste, especially textile waste, there are many cases where two or more colors are mixed rather than a single color. In such cases, by cutting the polymer waste into an appropriate size, the cut pieces can be made up of only one color. Therefore, if the polymer waste is made up of only one solid color, cutting may not be necessary. In the cutting process, each piece can be cut into an appropriate size, for example, so that the length or diameter of one side is 0.1 cm to 30 cm. However, if the length or diameter of one side is less than 0.1 cm, too much energy may be input into the cutting, and too many microplastics may be generated during the dye extraction or re-dyeing process, which may increase the amount of fibers that may be lost. If it exceeds 30 cm, the cut pieces may include two or more color areas, and a non-contact surface with the solvent may be created, which may lower the extraction efficiency.

[0051] The above step a-2) is a step of measuring the color value of polymer waste, and color values ​​by at least one color system among the above-mentioned HCV, RGB, HEX, HSL, HSV, HWB, Lab, CMYK, LCH, XYZ, OKLAB, OKLCH, RGBA, and HSLA can be used.

[0052] Step a-3) above is a step for classifying polymer waste by color value range. At this time, colorless waste pieces may be classified separately, as described above.

[0053] The above step b) is a step of contacting a disperse dye with a first compound to elute it into the first compound. The first compound has a stronger mutual attraction with a polymer having an ester functional group than the mutual attraction between the disperse dye and the polymer, so that the first compound can very quickly and effectively extract the disperse dye from polymer waste having an ester functional group by reducing or interfering with the mutual attraction between the polymer resin and the dyed disperse dye. In addition, since it does not cause serious physical or chemical deformation of the polymer waste having an ester functional group, it has the advantage of being highly effective in recovering and recycling materials.

[0054] When extracting color-specific disperse dyes by contacting the first compound with polymer waste having an ester functional group separated by color, the temperature range is preferably 70°C to 200°C, and more preferably 120°C to 150°C.

[0055] In the step b), in extracting the disperse dye from the colored polymer waste having the ester functional group, the contact time between the colored polymer waste having the ester functional group and the first compound can be controlled so that sufficient extraction of the disperse dye can be performed while minimizing damage or loss of the polymer having the ester functional group.

[0056] In addition, the step b) extracts the disperse dye by contacting the first compound with the colored polymer waste having an ester functional group in the temperature range described above to elute the disperse dye from the waste, and this extraction process can be repeated once or multiple times to extract the disperse dye. The method of the present invention can be performed at normal pressure and can rapidly decolorize at a relatively low temperature, thereby reducing energy consumption. In addition, the organic solvent used to extract the disperse dye can be reused for re-dyeing, and most or part of the extractant can be recovered or reused without a separate separation process that consumes excessive energy, thereby implementing an environmentally friendly and economical dye recycling process.

[0057] In addition, step b) above can be applied to a method of effectively extracting a disperse dye from waste by heating the first compound containing the extracted disperse dye and continuously refluxing and resupplying the vaporized first compound therefrom, thereby maintaining continuous contact of the refluxed liquid first compound with the polymer waste having an ester functional group in the extraction of a dye from the polymer waste using the first compound, thereby effectively extracting the disperse dye from the waste. A Soxhlet extractor can be used as a representative method for the extraction.

[0058] Additionally, the mixture from which the disperse dye is extracted in step b) can be heated to a temperature close to the boiling point of the first compound in order to reflux only the first compound among the components.

[0059] The extract mixture containing the dye can be subjected to additional evaporation or distillation processes to recover most of the initially applied first compound, and the dye remaining after removal of the first compound can be recovered and reused in a concentrated form.

[0060] According to one embodiment of the present invention, a method for re-dyeing polymer fibers having an ester functional group to recycle dyes classified and recovered includes the steps of: contacting polymer fibers having an ester functional group with a dye solution in which a first compound, a second compound, and a disperse dye are mixed with each other to dye the polymer fibers having an ester functional group; wherein the first compound is at least one selected from monocyclic aromatic compounds substituted with at least one alkoxy functional group having 1 to 2 carbon atoms, i.e., methoxy or ethoxy functional groups; and the second compound may be at least one selected from water; or a polyhydric alcohol having two or more alcohol functional groups. The polyhydric alcohol preferably has 2 to 6 carbon atoms, but is not limited thereto, and may be selected from ethylene glycol, glycerol, diethylene glycol, triethylene glycol, and the like.

[0061] FIG. 2 is a liquid-liquid phase equilibrium diagram with the composition ratio of the first compound and the second compound and the temperature as variables. In the outer region of the curve based on the phase boundary region, the first compound and the second compound are completely mixed with each other to form a single phase (homogeneous phase), and in the inner region of the curve, the first compound and the second compound have limited solubility in each other, so they form two phases. When a disturbance is applied to the equilibrium state forming two phases, i.e., a point inside the curve adjacent to the phase boundary, one compound can be very finely dispersed into the other compound to form microdroplets, and the size of the microdroplets becomes smaller as it approaches the critical point which exists near the highest temperature forming the two phase region, so the dispersibility of the dye included in the mixture can be increased.

[0062] Accordingly, a re-dyeing method can be applied in which the mixed solvent containing the disperse dye is brought into contact with a polymer resin having an ester functional group at a temperature range where the first compound and the second compound can form a single phase or microdroplets, i.e., a point between 90°C and 159°C, thereby inducing dyeing by physical bonding between the dye and the polymer, and changing the conditions to irreversible so that further material transfer of the dye does not occur, thereby fixing the dye to the fiber.

[0063] The change to the above irreversible condition is not limited to a specific method, but a method of lowering the temperature of the mixed solvent in contact with the polymer having the ester functional group to less than 70°C may be used, and lowering it to a range from room temperature to 50°C may be more preferable.

[0064] The dyeing method of a polymer having an ester functional group according to the present invention may be characterized by including the steps of: i) heating a mixed dye solution containing a first compound, a second compound, and a disperse dye to a predetermined temperature and bringing the mixed dye solution into contact with a polymer having an ester functional group; and ii) lowering the temperature of the mixture at which the contact occurs so that the disperse dye is fixed within the chain of the polymer.

[0065] The above step i) is a step for inducing penetration of a disperse dye into a polymer matrix having an ester functional group to ensure a uniform dye concentration. In order to improve dyeing leveling properties after dyeing, it may be more preferable to configure the mixed dye solution so that it is adjacent to the phase boundary region so that the first compound is finely dispersed within the second compound. To this end, a method for adjusting the composition of the compounds constituting the mixed dye solution or heating the dye solution so that the temperature approaches a critical point may be used.

[0066] At this time, the temperature of the mixed dye solution may be in the range of 90°C to 159°C, and preferably in the range of 100°C to 130°C. When the temperature is 90°C or higher, the chain movement of the polymer having an ester functional group actively progresses, so that the polymer sufficiently swells, and the disperse dye particles can more freely penetrate between the chains of the polymer. When the contact temperature is lower than 90°C, the disperse dye does not provide sufficient binding energy to interact with the polymer having an ester functional group, so that dyeing does not occur dominantly. At an excessively high temperature of 160°C or higher, the migration rate may increase more than the dyeing rate, the vaporization rate of the organic solvent constituting the dye bath may become faster, and in an open system exposed to atmospheric pressure, boiling of some solvents may occur. In addition, chemical transformation of the dye may also proceed rapidly when exposed to high temperatures.

[0067] After the mixed dye solution is introduced into the region adjacent to the upper boundary according to the above heating method, contact with the mixed dye solution is maintained within the above temperature range for a predetermined time, for example, 10 seconds to 1 hour, preferably 1 minute to 10 minutes, so that the disperse dye can sufficiently penetrate between the chains of the polymer having an ester functional group.

[0068] i) In step, the relative content ratio of the first compound and the second compound may be mixed at a weight ratio of 1:99 to 99:1, and preferably, may be mixed at a weight ratio of 10:90 to 30:70.

[0069] The disperse dye in the above step i) may be a regenerated disperse dye extracted and recovered from a colored polymer, and the method of the present invention described above may be used to recover the dye.

[0070] The above step ⅱ) is a step in which the temperature of the mixed dye solution is lowered after the dye particles have sufficiently penetrated between the chains of the polymer, thereby fixing the dyed dye so that it has a strong mutual attraction with the polymer having an ester functional group.

[0071] At this time, the temperature of the mixed dye solution can be lowered to below 70°C to fix the dyed dye, and preferably, it can be lowered to a range of room temperature to 50°C. The temperature lowering speed of the cooling process is preferably 0.1°C to 20°C per minute, and more preferably 1°C to 5°C per minute.

[0072] Afterwards, the polymer having the dyed ester functional group in the mixed dye solution is separated, the dye solution remaining on the fiber is physically removed, and then the polymer is washed with an organic solvent such as water or alcohol, or dried to remove all of the first and second compounds absorbed into the polymer, thereby finally producing a dyed polymer. Meanwhile, the dye solution mixed with the disperse dye used in the dyeing process can be utilized for repeated dyeing, and if necessary, only the first and second compounds can be distilled to isolate and recover the regenerated disperse dye itself.

[0073] In addition, the present invention provides a method for recycling a disperse dye contained in waste colored polymer having an ester functional group, wherein the disperse dye is extracted from a colored polymer having an ester functional group using a first compound, and then the first compound used for the extraction is used for dyeing another polymer without being separated.

[0074] The method comprises the steps of: a) separating colored polymer waste having an ester functional group by color; b) contacting the colored polymer waste having an ester functional group separated by color through step a) with a first compound to elute a disperse dye in the colored polymer waste into the first compound; c) adding a second compound to the first compound solution from which the disperse dye obtained in step b) has been eluted to obtain a mixed dye solution; and d) contacting the mixed dye solution with a polymer having an ester functional group to dye the polymer having the ester functional group; wherein the first compound comprises at least one selected from monocyclic aromatic compounds substituted with at least one alkoxy functional group having 1 to 2 carbon atoms, i.e., methoxy or ethoxy functional group, and the second compound comprises at least one selected from water or polyhydric alcohols having two or more alcohol functional groups.

[0075] In addition, as in the method for recovering a disperse dye from colored polymer waste having an ester functional group according to the present invention described above, the step a) may include: a-1) cutting the colored polymer waste having an ester functional group into a predetermined size; a-2) measuring the color value of the polymer waste piece having an ester functional group cut in the step a-1); and a-3) classifying the polymer waste piece having an ester functional group by color based on the color value of the polymer waste piece having an ester functional group measured in the step a-2) and the color value range set for each color of the disperse dye.

[0076] Since the details of steps a) and b) above are as described above, the same description is omitted to avoid repetition of the description.

[0077] The above step c) is a step of obtaining a mixed dye solution by adding a second compound to the first compound solution from which the disperse dye obtained in step b) has been eluted. The mixed solution further containing the disperse dye obtained through contact with the first compound in step b) may contain fine fragments of polymers having ester functional groups. To remove these, physical filtration may be additionally performed, and the amount of the first compound may be increased or decreased as necessary for the purpose of adjusting the concentration of the disperse dye, etc.

[0078] The content of the second compound added above can be adjusted in proportion to the amount of the first compound, and the relative content ratio of the first compound and the second compound is preferably a weight ratio of 1:99 to 99:1, and more preferably a weight ratio of 10:90 to 30:70.

[0079] The above step d) is a step of dyeing a polymer having an ester functional group by bringing the mixed dye solution into contact with the polymer having an ester functional group, and corresponds to steps i) and ii) of the method for dyeing a polymer fiber having an ester functional group described above. Therefore, the detailed conditions of the above step d) can be referred to the contents described in the above steps i) and ii), and a detailed description is omitted.

[0080] Hereinafter, a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group according to one embodiment of the present invention will be described in more detail through examples, comparative examples, and experimental examples.

[0081] Experimental Example 1: Method for recovering disperse dyes

[0082] After selecting fibers by color using a spectrophotometer from colored mixed waste fibers, only 14 g of colored waste fibers having a specific color range containing a polymer having an ester functional group were selected and placed in a chamber of a Soxhlet extractor, and 90 g of an extractant corresponding to the first compound (an aromatic compound having an alkoxy functional group having 1 to 2 carbon atoms) was placed in the lower heating section and heated to generate vapor, and then the liquefied extractant was supplied to the container by continuous reflux through a condenser connected to the container where the fibers were placed, thereby allowing the heated extractant to come into contact with the fibers.

[0083] A colored substance (dye) can be separated from a fiber by continuously adding a first compound to a dye extractant to induce direct contact and discharging the extract downward. The process of discharging the extract to the lower heating section can be repeated two or more times within the Soxhlet extractor, and dominant de-dyeing can proceed when the contact temperature between the fiber and the extractant is maintained at 100°C to 150°C. The temperature of the heating section of the Soxhlet extractor is maintained at a temperature close to the boiling point of the extractant, and the contact temperature between the polymer and the extractant can be maintained or controlled at a temperature about 0°C to 65°C lower than the boiling point of the extractant.

[0084] In the lower heating section, only the first compound is vaporized, enabling continuous resupply, and by leaving it under the same conditions for 60 to 120 minutes, most of the dye can be extracted and separated from the fiber. The extracted dye mixture may contain micro-plastic fragments of fiber polymers having ester functional groups, and some of them can be removed using a filter equipped with a glass fiber filter (model name: Whatman No. 2). A polyhydric alcohol having two or more alcohol functional groups is added to the obtained dye mixture, and the concentration of the first compound is adjusted to prepare a dye bath containing a regenerated dye, which can be directly applied to the re-dyeing of fibers having ester functional groups.

[0085] Meanwhile, the dye mixture obtained through the filtration process above can also be used to recover a solid-state regenerated dye by removing the solvent. The dye mixture obtained as the filtrate from the filtration process was transferred to a 250 ml round flask and immersed in a water bath maintained at 50°C, and the first compound was evaporated and recovered using a vacuum rotary evaporator. The dried dye obtained as a solid was transferred to a vacuum dryer maintained at a vacuum of 1 mbar or less and a temperature of 60°C, and left for more than 12 hours, thereby producing a regenerated dye from which the extractant was completely removed. The produced powder can be used as a sample for nuclear magnetic resonance (NMR) analysis to analyze the chemical structure of the regenerated dye.

[0086] Raw material 1

[0087] A colorless polymer raw material was prepared by cutting an undyed polyester fiber fabric into a rectangular shape with one side length of approximately 3 cm and the other side length of approximately 3.5 cm.

[0088] Raw material 2

[0089] A mixture of waste polyester fibers having at least 12 colors processed with unknown dyes under different dyeing conditions was prepared as colored polymer raw material 2.

[0090] Raw material 3

[0091] According to generally known water-based dyeing conditions, a dye bath was prepared by mixing Disperse Red 1 as an azo-based disperse dye and TWEEN 20 as a dispersant in an excess amount of water at a weight ratio of 1:1 and a dye weight ratio of 1.0% (owf), and then stirring for 40 minutes in an autoclave maintained at 130°C to prepare a plain polyester fiber fabric dyed in red as raw material 3.

[0092] Raw material 4

[0093] Raw material 4 was prepared by dyeing and processing in the same manner as the preparation process for raw material 3, except that Disperse Red 9, an anthraquinone-based disperse dye, was used instead of Disperse Red 1, and the weight ratio of the dye was set to 1.5% (owf) when forming the dye bath.

[0094] Raw material 5

[0095] Raw material 5 was prepared by dyeing and processing in the same manner as the preparation process for raw material 3, except that Dystar Dianix Blue ER 150% (CI Disperse Blue 56), a commercial dye, was used instead of Disperse Red 1.

[0096] Raw material 6

[0097] Raw material 6 was prepared by dyeing and processing in the same manner as the preparation process for raw material 3, except that Dystar Dianix Blue ER 150% (CI Disperse Blue 56), a commercial dye, was used instead of Disperse Red 1 and the weight ratio of the dye was set to 1.5% (owf) in the dye bath composition.

[0098] Raw material 7

[0099] A mixture of red fibers dyed with dyes (Disperse Red 1 and Disperse Red 9) having different chemical structures from mixed colored polyester fibers but separated into the R series in terms of Munsell color (H) value during the color classification process was prepared as raw material 7.

[0100] Temperature conditions for re-dyeing of regenerated dyes

[0101] The following comparative examples and examples are intended to compare the dyeing effects according to temperature when extracting a dye (CI Disperse Red 1) whose main components are known from waste fiber (raw material 3) having an ester functional group according to the dye extraction method of Experimental Example 1 and re-dyeing it using the same according to the present invention.

[0102] Example 1

[0103] In a 50 ml pressure-resistant round bottom flask container containing 4.0 g of ethylene glycol and 1.0 g of methoxybenzene (anisole), a dye (CI Disperse Red 1) recycled from colored waste fibers after color sorting was added at a weight ratio of 0.5%, heated, and when the internal temperature reached 130°C, maintained at the same temperature, and stirred at 500 rpm for 15 minutes using a magnetic stirrer.

[0104] After confirming that the dye was uniformly dissolved in the mixed solvent, a piece of plain polyester fiber of raw material 1 that had not been dyed was added and exposed to the dyeing conditions for 1 minute while maintaining stirring, then naturally cooled to room temperature and stirred at 300 rpm for 5 minutes. The piece of polyester fiber was taken out using tweezers, immersed in 20 ml of prepared room temperature water for about 2 seconds, washed 2 to 3 times using 20 ml of ethanol, and left in a flask containing 20 ml of ethanol for about 5 minutes to completely remove the dye that had not been dyed on the polyester fiber. After that, the fiber was transferred to a glass evaporating dish, placed in a dryer maintained at 80°C, and dried for more than 12 hours to produce a dyed fiber. The re-dyed fibers finally obtained through drying were measured for surface dye uptake and color using a spectrophotometer (manufacturer: Konica Minolta model number: CM-3700D) to determine their color characteristics. The surface dye uptake was measured by measuring the surface reflectance of the dyed fibers at the maximum absorption wavelength (λmax: 500 nm) of the fibers under a D65 light source and a 10° field of view, and the K / S value was calculated using the Kubelka-Munk equation.

[0105]

[0106] Here, K is the absorption coefficient, S is the scattering coefficient, and R is the surface reflectance.

[0107] In addition, information on the fiber color measured by the spectrophotometer is provided in the form of HV / C values ​​according to the Munsell color system and color coordinates L according to the CIELAB color system. * a * b * It was converted to a value and produced. The Munsell color system is a color system that describes color by three attributes: hue (H), value (V), and saturation (C). Among these, in the Munsell color system, the hue (H) value is arranged into 10 colors in total by inserting 5 intermediate colors of YR, GY, BG, PB, and RP into the four primary colors of R (red), Y (yellow), G (green), B (blue), and P (purple), and each of these can be divided into 10 parts to distinguish and express 100 colors. L * a * b * The values ​​expressed as are coordinates of the color space standardized by the International Commission on Illumination (CIE), L* is a number expressed from 0 (black) to 100 (white) indicating lightness, and a* and b* are numbers expressed along the complementary color axes of red (+) / green (-) and yellow (+) / blue (-), respectively.

[0108] Comparative Example 1

[0109] Fibers were dyed in the same manner as in Example 1, except that the temperature was set to 80°C.

[0110] Example 2

[0111] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 90°C.

[0112] Example 3

[0113] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 100°C.

[0114] Example 4

[0115] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 110°C.

[0116] Example 5

[0117] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 120°C.

[0118] Example 6

[0119] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 140°C.

[0120] Example 7

[0121] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 150°C.

[0122] Comparative Example 2

[0123] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 160°C.

[0124] In the above Examples 1 to 7, a mixed solvent was prepared and used so that the weight ratio of methoxybenzene as the first compound and ethylene glycol as the second compound was 20% and 80%, respectively. After sorting and extracting waste polyester fibers, a red azo-based disperse dye (CI Disperse Red 1) was added to the mixed solvent so that the dye bath was formed at a weight ratio of 0.5%, and the re-dyeing effect was observed using different temperature conditions. The color characteristics of each fiber re-dyeing using the recycled dye were observed using a spectrophotometer. Table 1 shows the surface dyeing amount (K / S), Munsell color system (HV / C), and color space coordinate values ​​(L) estimated from the results measured by the spectrophotometer. * a * b * ) is shown together with the dyeing conditions.

[0125]

[0126] The results in Table 1 above clearly show that completely different dyeing results are obtained depending on the temperature applied to the dyeing, even though the same amount of recycled dye was used. Referring to the results of Examples 1 to 7 performed according to the present invention, the Munsell color (H) showed a vivid and uniform red (R) re-dyeing result within the range of 5.7R to 6.6R. In the temperature range (90-130℃) shown in Examples 1 to 5, as the temperature increased, the lightness (V) value decreased from 6.29 to 5.31, and the saturation (C) value increased from 10.43 to 12.67. This can be expected as a result of the increase in dyeing amount at high temperatures within the range. When the dyeing temperature was increased from 90℃ to 130℃, the K / S value, an indicator indicating the amount of dye applied to the fiber surface, was found to gradually increase from 2.79 to 8.08, and the highest value was shown at 130℃.

[0127] On the other hand, in Comparative Example 1 (80°C) where the re-dyeing temperature was too low, the leveling property was excellent, but only a very limited number of dyes were introduced with a K / S value of 1.5 or less, and in Comparative Example 2 (160°C) where an excessively high re-dyeing temperature was applied, the color of the fiber surface was observed to be uneven.

[0128] The reason why the dye leveling is not good at high temperatures is that the kinetic energy of the dye molecules themselves that have penetrated into the fiber matrix increases, which can increase the desorption rate of the dye compared to the dyeing rate, and the migration rate of the dye to the outside of the polymer matrix can also vary depending on the fiber location, which can result in the dye remaining unevenly on the fiber surface.

[0129] In conclusion, it can be seen that the dyeing method according to the present invention can vary the degree of dyeing depending on the temperature, and that the greatest amount of dye can be effectively introduced into the dyed fiber when the re-dyeing temperature is maintained at 130°C.

[0130] Comparison of dyeing effects according to changes in dye concentration

[0131] Example 1 and Examples 8 to 14 were conducted to compare the effects of re-dyeing when the concentration of the regenerated dye in the dye bath was changed. The experiments were conducted under the same conditions as Example 1 except that the concentration of the regenerated dye was prepared differently.

[0132] Example 8

[0133] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 0.25% by weight in the dye bath composition.

[0134] Example 9

[0135] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 1.0% by weight in the dye bath composition.

[0136] Example 10

[0137] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 1.5% by weight in the dye bath composition.

[0138] Example 11

[0139] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 2.0% by weight in the dye bath composition.

[0140] Example 12

[0141] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 2.5% by weight in the dye bath composition.

[0142] Example 13

[0143] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 3.0% by weight in the dye bath composition.

[0144] Example 14

[0145] Fibers were dyed in the same manner as in Example 1, except that the regenerated dye was added in an amount of 3.5% by weight in the dye bath composition.

[0146] Table 2 shows the dye absorption (K / S), Munsell color system (HV / C), and color space coordinates (L) of fibers re-dyed according to the methods of the above examples, measured using a spectrophotometer. * a * b * ) are compared and displayed.

[0147]

[0148] When the Munsell color (H) values ​​measured in Example 1 and Examples 8 to 14 were observed, even though the concentration of the red regenerative dye having Disperse Red 1 as the main component varied greatly from 0.25% to 3.5%, the Munsell color (H) values ​​were located within the range of 6.2R to 6.9R, and no significant deviation in color was observed.

[0149] On the other hand, the K / S value, which is an indicator of the amount of dye applied to the fiber surface, increases in proportion to the concentration of the dye in the applied dye bath (maximum 19.47). This is the brightness (L) among the color space coordinate values. * ) was also observed to change significantly in the value. As the amount of dye introduced increased, the final color of the fiber became significantly darker, and the lightness (L * ) was found to be lowered to below 40. By using the dye regenerated according to the present invention, it was possible to express the color of the fiber before extraction, and it was found that by adjusting the concentration of the mixed solution (dye solution) recovered together with the regenerated dye, it was possible to control the brightness of the fiber and implement the desired color.

[0150] Differences in performance of mixed dye solutions using single solvent and mixed solvent

[0151] The following examples and comparative examples are intended to explain a method for forming a mixed solvent that can be effectively applied in the process of re-dyeing fibers using recycled disperse dyes. In the present invention, the solvent for re-dyeing recycled dyes can be formed in the form of a mixture of a first compound and a second compound. For this purpose, an aromatic compound having an alkoxy functional group with 1 to 2 carbon atoms that can be used for dye extraction from waste fibers can be used as the first compound, and water or a polyhydric alcohol having two or more alcohol functional groups, or a mixture thereof, can be used as the second compound.

[0152] Example 15

[0153] Fibers were dyed in the same manner as in Example 1, except that the dyeing temperature was set to 100°C, and methoxybenzene as the first compound and ethylene glycol (water content of 75% by weight) as the second compound were mixed to a weight ratio of 20% and 80%, respectively, to prepare the dyeing bath.

[0154] Example 16

[0155] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and water as the second compound in weight ratios of 0.2% and 99.8%, respectively, and that the dyeing temperature was set to 100°C.

[0156] Comparative Example 3

[0157] Fibers were dyed in the same manner as in Example 1, except that only methoxybenzene was used as a solvent as the first compound in forming the dye bath.

[0158] Comparative Example 4

[0159] Fibers were dyed in the same manner as in Example 1, except that only ethylene glycol was used as a solvent as the second compound in forming the dye bath.

[0160] Table 3 is to specifically explain the method of forming a dye bath according to the present invention, in which the recycled dye extracted and recovered by applying the first compound after sorting waste fibers by color is applied to re-dyeing fibers. The dyeing process of all recycled dyes was performed under atmospheric pressure conditions. For this purpose, in the case of Examples 15 and 16 in which some or all of the second compound was water, dyeing was performed while maintaining the dye bath temperature at 100°C. The dyed fibers were observed for their color characteristics using a spectrophotometer, and the dye absorption (K / S), Munsell colorimetric value (HV / C), and color space coordinate value (L) of the fiber surface were estimated from this. * a * b * ) are summarized and presented in Table 3.

[0161]

[0162] Looking at the results of Comparative Examples 3 and 4 using a single solvent in the re-dyeing process of dye recovered from waste fibers, even though the dyeing temperature was maintained at 130°C to provide sufficient energy for dyeing, the measured K / S value was observed to be around 2, indicating that the amount of dye introduced was very low. Unlike the results of Example 1 in which dyeing was performed under the same conditions using a mixed solvent according to the method of the present invention, only a very small amount of dye was observed to be dyed onto the fiber, and accordingly, the Munsell color (H) value also showed a light tone of around 5.5R.

[0163] On the other hand, as in the previous examples (Examples 2 to 4) in which dyeing was performed by lowering the dyeing temperature, it was observed that the re-dyeing efficiency was significantly increased compared to the dyeing results of Comparative Example 3 or Comparative Example 4 even when a mixed solvent was used but a large amount of water was added to the second compound or the concentration of the first compound was significantly limited to 0.2% or less.

[0164] Referring to the results of Examples 15 and 16, the Munsell color (H) values ​​were measured as 6.6R and 7.6R, which did not significantly deviate from the results of Example 1, and the dyeing amount was also observed to be high.

[0165] In summary of the results in Table 3 above, unlike the existing dyeing method (aqueous system) that requires high temperature and high pressure dyeing conditions because an excessive amount of water is used and uses a separate dispersant to induce high dispersion of a disperse dye with low hydrophilicity, the re-dyeing method (non-aqueous system) of a regenerated dye according to the present invention uses a small amount of solvent mixture under normal pressure conditions, so it is very economical and can introduce the dye into the substrate very quickly and uniformly through simple contact with the fiber, so it can achieve very effective re-dyeing of fibers.

[0166] Optimal composition of mixed solvent for re-dyeing with regenerated disperse dyes

[0167] The following examples and comparative examples represent experimental examples conducted to compare the dyeing effects according to the composition of the mixed solvent.

[0168] Example 17

[0169] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 40% and 60%, respectively.

[0170] Example 18

[0171] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 35% and 65%, respectively.

[0172] Example 19

[0173] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 30% and 70%, respectively.

[0174] Example 20

[0175] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 25% and 75%, respectively.

[0176] Example 21

[0177] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 22% and 78%, respectively.

[0178] Example 22

[0179] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 18% and 82%, respectively.

[0180] Example 23

[0181] Fibers were dyed in the same manner as in Example 1, except that the dye bath was prepared by mixing methoxybenzene as the first compound and ethylene glycol as the second compound in weight ratios of 15% and 85%, respectively.

[0182] Table 4 shows a comparison of the dyeing characteristics observed by maintaining the dyeing conditions constant but changing the composition of the first and second compounds.

[0183]

[0184] Referring to the results of Comparative Examples 3 and 4 using a single solvent, only a very limited amount of dye was dyed on the fiber, but in the case of Example 1 and Examples 18 to 23, in which the first and second compounds were mixed and used, very effective and systematic dyeing was performed despite only a short time of contact with the dye solution. In particular, the largest amount of dye was dyed in the region near the phase boundary indicated by (b) in the phase equilibrium diagram of Fig. 2 (for example, Examples 1, 21, and 22), and excellent dyeing leveling was also observed.

[0185] Dye recovery and recycling from waste fibers dyed with unknown dyes

[0186] The following examples illustrate specific examples of methods for sorting mixed colored waste fibers of unknown types and amounts of dyes by color, recovering recycled dyes from each, and then applying them to re-dyeing to extract dyes of various colors and recycle them.

[0187] Example 24

[0188] From the colored waste polyester fibers (raw material 2) discharged by mixing at least 12 different colors, fibers having similar or identical colors were spectroscopically classified, and each of the classified colored fibers was recovered as regenerated dyes according to the method of Experimental Example 1, and dyeing was performed using the same method as Example 1, but the extracted dyes were distinguished according to fiber color and re-dyeing was performed.

[0189] As shown in Fig. 1, after re-dyeing according to the process of re-applying the color-specific dyes obtained after sorting from the mixed colored waste fibers of various colors to the dyeing of the fibers, the dyeing characteristics of the fibers before and after the re-dyeing were compared in Table 5. The dyed fibers were observed for their color characteristics using a spectrophotometer, and the dyeing amount (K / S), Munsell colorimetric value (HV / C), and color space coordinate value (L) of the fiber surface were estimated from this. * a * b * ) are summarized and presented in Table 5.

[0190]

[0191] Figure 1 schematically illustrates the process of recycling dye by classifying waste fibers by color, recovering dyes by color, and re-dyeing using the recovered dyes.

[0192] After classifying the colors from the mixed-color waste fibers of raw material 2, the dyes extracted from the fibers by color were re-dyeed on undyed plain polyester fibers (raw material 1) according to the method of the present patent, and the color characteristics of the fibers obtained through re-dyeing were compared with those of the initial fibers before de-dyeing, as shown in Table 5.

[0193] Most re-dyed fibers exhibited color (H) values ​​very similar to those of the initial waste fibers with unknown dye uptake prior to bleaching, and other color characteristics were also similarly achieved. This suggests that no significant color distortion occurred even when the recycled dye was reintroduced into the fibers.

[0194] Meanwhile, in some corresponding fibers (using initial dyes and recycled dyes) dyed with different methods for each color, there were slight deviations in the measured Munsell Value (V) and Munsell Chroma (C) values. This is because the dyeing conditions and dye concentrations at the time of manufacturing the waste fiber (raw material 2) were unknown, and the amount of dye extracted during the redyeing process could not be precisely controlled. It is expected that perfectly reproducing or imitating the same color system as the initial fiber raw material can be easily achieved through a simple, repetitive trial and error process of increasing or decreasing the amount of recycled dye for each color.

[0195] Comparison of color characteristics of colored fibers dyed using different dyeing methods

[0196] The following are comparative examples and experimental examples conducted to compare the color characteristics of colored fibers prepared according to the existing dyeing method (aqueous system) in which dyeing is performed by adding a dye and dispersant to a large amount of water, and fibers dyed using a regenerated dye according to the method of the present patent (non-aqueous system).

[0197] Example 25

[0198] The dye introduced into raw material 4 was extracted and recovered according to the process of Experimental Example 1, and the fiber was dyed in the same manner as in Example 1, except that the dye bath was composed so that the obtained regenerated dye (main component: CI Disperse Red 9) was 1.5% by weight.

[0199] Example 26

[0200] The dye introduced into raw material 5 was extracted and recovered according to the process of Experimental Example 1, and the fiber was dyed in the same manner as in Example 1, except that the dye bath was composed so that the obtained regenerated dye (main ingredient: CI Disperse Blue 56; commercial name: Dystar Dianix Blue ER 150%) was 0.25% by weight.

[0201] Example 27

[0202] The dye introduced into raw material 6 was extracted and recovered according to the process of Experimental Example 1, and the fiber was dyed in the same manner as in Example 1, except that the dye bath was composed so that the obtained regenerated dye (main ingredient: CI Disperse Blue 56; commercial name: Dystar Dianix Blue ER 150%) was 0.5% by weight.

[0203] Comparative Example 5

[0204] In the same way as the color measurement process of the fiber in Example 1, the color of raw material 3 was measured using a spectrophotometer, and from this, the K / S value, the HV / C value according to the Munsell color system, and the color coordinate L according to the CIELAB color system * a * b * The value was calculated.

[0205] Comparative Example 6

[0206] In the same way as the color measurement process of the fiber in Example 1, the color of raw material 4 was measured using a spectrophotometer, and from this, the K / S value, the HV / C value according to the Munsell color system, and the color coordinate L according to the CIELAB color system * a * b * The value was calculated.

[0207] Comparative Example 7

[0208] In the same way as the color measurement process of the fiber in Example 1, the color of raw material 5 was measured using a spectrophotometer, and from this, the K / S value, HV / C value by the Munsell color system, and color coordinate L by the CIELAB color system were determined. * a * b * The value was calculated.

[0209] Comparative Example 8

[0210] In the same way as the color measurement process of the fiber in Example 1, the color of raw material 6 was measured using a spectrophotometer, and from this, the K / S value, HV / C value by the Munsell color system, and color coordinate L by the CIELAB color system were determined. * a * b * The value was calculated.

[0211] Table 6 shows the color of colored fibers prepared by the conventional water-based dyeing method (Comparative Examples 5 to 8), and colored re-dyed fibers prepared by classifying waste fibers with introduced color by color and recovering dyes therefrom, and using the recovered recycled dyes. The colors were measured using a spectrophotometer, and the surface dye uptake (K / S), Munsell color system (HV / C), and color space coordinates (L) estimated from the color measured. * a * b * ) is shown by comparing information about them.

[0212]

[0213] In aqueous dyeing methods using excess water and dispersants, the dyeing solution can be prepared based on the amount of dye used relative to the weight of fiber (owf). Comparative Examples 5 and 6 in Table 6 show that red fibers were prepared according to the aqueous dyeing method using azo (Disperse Red 1) and anthraquinone (Disperse Red 9) disperse dyes, but colored fibers were produced based on the point where the color characteristics of the fibers obtained after dyeing do not change rapidly even if the amount of dye in the dyeing solution is increased.

[0214] The colored fibers prepared in this way were dyed in a dye bath so that the concentration of the regenerated dye was 1.5% by weight according to the present invention, and the color was measured and the dyeing characteristics were compared and analyzed using a spectrophotometer together with the dyed fibers (Examples 10 and 25). When the measurement results for the fibers prepared by different dyeing methods, i.e., the initial fibers and the fibers dyed with the regenerated dyes, were compared with each other, it was observed that not only the color but also the lightness, saturation, and dyeing amount, all color characteristics, were very similar.

[0215] Commercial dye (CI Disperse Blue 56) was applied for dyeing, and the dyeing process was performed by changing the concentration of the dye bath (1.0% and 1.5% in owf) according to the water-based dyeing process, and the dyed colored fibers were shown in Comparative Examples 7 and 8.

[0216] According to one embodiment of the present invention, when fibers prepared by directly applying a regenerated dye to a mixed solvent consisting of only the first compound and the second compound and then dyeing them were compared with fibers prepared through water-based dyeing (Comparative Examples 7 to 8), the color characteristics were observed to be very similar to those of fibers dyed by preparing a dye bath so that the dye concentration was 0.25% (Example 26) and 0.5% (Example 27) by weight. In the results measured through a spectrophotometer, the color (H) values ​​were classified into the same series, and the fiber surface dyeing amount (K / S) and color space coordinates (L * a * b * ) Also, a very small error was observed. This result proves that the dye recycling method according to the present invention can be effectively used without any special limitations to implement the same dyeing effect and color characteristics as colored fibers prepared according to the existing dyeing processing method.

[0217] Meanwhile, FIGS. 3 to 6 show the results of nuclear magnetic resonance analysis on the model dyes before use in dyeing and the regenerated dyes recovered from fibers colored by Disperse Red 1 and Disperse Red 9 according to the methods of Examples 10 and 25. 1 H NMR and 13 This is a C NMR spectrum. In the recycled dye, additional characteristic peaks attributed to residual polyester polymer particles were observed, but no significant differences were observed in the chemical shifts indicating the dye structure compared to those measured for the model dye. This indicates that the chemical structure of the dye itself was not altered during the dye recovery and recycling process of the present invention.

[0218] Color characteristics of fibers re-dyed with composite dyes

[0219] The following example is an observation of color characteristics by re-dyeing fibers with a composite dye extracted from red mixed waste fibers that were dyed with dyes having completely different chemical structures but classified as R in the Munsell color (H) value.

[0220] Example 28

[0221] A composite dye was extracted and recovered from a portion of raw material 7 according to the process of Experimental Example 1, and fibers were dyed in the same manner as in Example 1, except that the dye bath was composed so that the obtained regenerated dye was 1.5% by weight. For the remainder of raw material 7, the dye was extracted and recovered according to the same method and conditions, and the re-dyeing process was repeated.

[0222]

[0223] Table 7 compares the color characteristics of fibers re-dyed using dyes extracted from waste fibers classified as red. The regenerated dyes obtained from the process of Example 28 were obtained by extracting from red mixed fibers without further classifying them according to the type of dye or slight color difference, although the Munsell color (H) values ​​from the mixed waste fibers were classified into the R series. The composition ratio of the composite dyes obtained twice was determined through pre-calibrated 1H NMR analysis, and the ratios of the azo disperse dye (Disperse Red 1) and the anthraquinone disperse dye (Disperse Red 9) were confirmed to be 68:32 (Red 1) and 56:44 (Red 2), respectively.

[0224] The color characteristic values ​​of the fibers re-dyed using these regenerated dyes were between the color characteristic values ​​measured in Examples 10 and 25, in which single-component regenerated dyes were used. In particular, the Munsell color (H) value observed in Example 28 did not significantly deviate from the average value of the colors measured in Examples 10 and 25, and no distortion, deformation, or offset of color occurred even when disperse dyes with different chemical structures were applied in combination. In addition, the K / S value, which indicates the dye absorption on the fiber surface, was measured to be relatively high at 14.9 to 15.1, and it was observed that the brightness and saturation did not significantly deviate from those of fibers to which a single-component regenerated dye was applied.

[0225] As described above with reference to the various examples of the present invention explaining the dyeing effect of the recycled dye, it was found that the recycled dye, which can be recovered from discarded fibers after consumption, does not present any technical problems in realizing various colors of new fibers. In addition, from the comparison of the NMR spectra of the dyes before and after the regeneration process, it was found that no change occurred in the chemical structure or properties of the dyes during the regeneration process. Therefore, the extraction of the dye, the composition of the mixed solution for re-dyeing, and the re-dyeing process, which can be performed according to one embodiment of the present invention, are methods for very effectively extracting and reusing dye materials that were previously discarded along with the fibers, and since separation and purification of the solvent used for extraction are unnecessary and the amount of wastewater can be reduced, it can be used as a very economical and environmentally friendly method for recycling dyes.

[0226] As specific aspects of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific descriptions merely represent preferred embodiments and are not intended to limit the scope of the present invention. Therefore, the substantial scope of the present invention is defined by the appended claims and their equivalents.

[0227] The present invention relates to a method for recovering and recycling a disperse dye from colored polymer waste having an ester functional group, wherein colored polymer waste having an ester functional group in which various colors are mixed is classified by color, and disperse dyes are extracted from the waste classified by color, thereby recovering disperse dyes by color from colored polymer waste having an ester functional group, and thus the present invention can be widely used in industrial fields that require a technology for separating a polymer having an ester functional group from waste containing a polymer having an ester functional group and other polymers and a technology for recovering disperse dyes by color.

Claims

1. A method for recovering disperse dyes from colored polymer waste having an ester functional group, a) a step of separating colored polymer waste having ester functional groups by color; and b) a step of contacting a first compound with a colored polymer waste having an ester functional group separated by color through the step a) above, thereby dissolving the disperse dye in the colored polymer waste into the first compound; A method for recovering a disperse dye from colored polymer waste having an ester functional group, characterized in that the first compound comprises a monocyclic aromatic compound substituted with at least one methoxy or ethoxy functional group.

2. In paragraph 1, Step a) above, a-1) A step of cutting colored polymer waste having an ester functional group into a predetermined size; a-2) a step of measuring the color value of a piece of polymer waste having an ester functional group cut in step a-1); and a-3) A method for recovering a disperse dye from colored polymer waste having an ester functional group, characterized by comprising a step of classifying the polymer waste pieces having an ester functional group by disperse dye color based on the color value of the polymer waste pieces having an ester functional group measured in step a-2) and the color value range set for each disperse dye color.

3. In paragraph 1, Step b) above, A method for recovering disperse dyes from colored polymer waste having an ester functional group, characterized in that the first compound is brought into contact with the polymer waste having an ester functional group separated by color through the above step a) at a temperature range of 70°C to 200°C to extract disperse dyes by color.

4. In a method for dyeing a polymer having an ester functional group, i) a step of heating a mixed dye solution containing a first compound, a second compound, and a disperse dye to a predetermined temperature and bringing it into contact with a polymer having an ester functional group; ii) a step of lowering the temperature of the mixed dye solution so that the disperse dye is fixed within the chain of the polymer; A method for dyeing a polymer having an ester functional group, characterized in that the first compound is a monocyclic aromatic compound substituted with at least one methoxy or ethoxy functional group, and the second compound is at least one of a polyhydric alcohol having two or more water or alcohol functional groups.

5. In paragraph 4, A dyeing method for a polymer having an ester functional group, characterized in that the above polyhydric alcohol has 2 to 6 carbon atoms.

6. In paragraph 4, A dyeing method for a polymer having an ester functional group, characterized in that the temperature of the mixed dye solution in the above step i) is 90°C to 159°C.

7. In paragraph 4, ⅱ) A dyeing method for a polymer having an ester functional group, characterized in that the temperature of the mixed dye solution is lowered to a temperature below 70°C in step 2.

8. In paragraph 4, i) A dyeing method for a polymer having an ester functional group, characterized in that the disperse dye in step is a regenerated disperse dye recovered from a colored polymer.

9. In paragraph 8, A dyeing method for a polymer having an ester functional group, characterized in that the above-mentioned regenerative disperse dye is obtained by the method of any one of claims 1 to 3.

10. A method for recycling disperse dyes contained in colored polymer waste having an ester functional group, a) A step of separating colored polymer waste having an ester functional group by color; b) a step of contacting a first compound with colored polymer waste having an ester functional group separated by color through step a) to elute the disperse dye in the colored polymer waste into the first compound; c) a step of adding a second compound to the first compound solution from which the disperse dye obtained in step b) has been eluted to obtain a mixed dye solution; and d) a step of contacting the mixed dye solution with a polymer having an ester functional group to dye the polymer having an ester functional group; A method for recycling a disperse dye contained in colored polymer waste having an ester functional group, characterized in that the first compound is a monocyclic aromatic compound substituted with at least one methoxy or ethoxy functional group, and the second compound is at least one polyhydric alcohol having two or more water or alcohol functional groups.

11. In paragraph 10, Step a) above, a-1) A step of cutting colored polymer waste having an ester functional group into a predetermined size; a-2) a step of measuring the color value of a piece of polymer waste having an ester functional group cut in step a-1); and a-3) A method for recycling a disperse dye contained in colored polymer waste having an ester functional group, characterized by comprising a step of classifying the polymer waste pieces having an ester functional group by color based on the color value of the polymer waste pieces having an ester functional group measured in step a-2) and the color value range set for each color of the disperse dye.

12. In paragraph 10, A method for recycling a disperse dye contained in colored polymer waste having an ester functional group, wherein the polyhydric alcohol has 2 to 6 carbon atoms.

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