Efficient depolymerization method for polymers containing ester functional groups and method for purifying the same

Abstract

To provide an extractant for selectively removing foreign substances from a polymer monomer comprising an ester functional group, and a purification method for removing foreign substances to prepare high-purity monomers.SOLUTION: The present invention provides an extractant comprising a compound represented by the following formula, and a purification method for preparing high-purity monomers by adding the compound to a polymer monomer, followed by mixing and liquid-liquid separation. R1 is any one selected from hydrogen, a hydroxy group, an aldehyde group, a carboxyl group, an alkyl group, a cycloalkyl group and an aryl group, n represents an integer of 0-5, if n is 2 or greater, each R1 may be the same or different, R2 represents a C1-C10 alkyl group, m represents an integer of 1-6, if m is 2 or greater, and each R2 may be the same or different.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This invention relates to a low-temperature glycolysis method for ester functional group-containing polymers by adding additives, and a colored high A method for removing foreign substances that may be contained in monomers from molecular depolymerization products, and a method using the same. This invention relates to a method for purifying Mar to high purity and to an environmentally friendly method for depolymerizing the colored polymer.

[0002] More specifically, it is identified in the glycolysis reaction of colored polymers containing ester functional groups. By adding this additive, it is possible to maintain a high depolymerization yield even at low temperatures. A considerate depolymerization method is used, adjusting the thermodynamic conditions of the resulting reaction product to achieve liquid-liquid phase equilibrium. A separation method that enables the selective separation of color-producing foreign substances, using liquid-liquid extraction A method for high-purity purification of addition monomers, and a low-value exchange esterification reaction free from harmful metals. Using a catalyst, harmful or degrading inorganic substances in the monomer product are removed. A colored polymer containing ester functional groups that can significantly reduce the amount of impurities. This relates to a method for high-purity purification of depolymerization reactions and monomer products. [Background technology]

[0003] Most discarded plastics end up in designated landfills where natural decomposition is difficult, or in natural habitats. Because it is discharged into dams, the severity of the environmental pollution problem is increasing day by day. Furthermore, natural components Even decomposable or biodegradable plastics are affected by factors such as the level of UV exposure, temperature, and the presence of degrading microorganisms. It can survive for several decades due to local environmental factors.

[0004] To solve these problems, novel plastic materials with short biodegradation cycles in their natural state are being developed. In addition to development, the physical recycling of plastics from the chemical decomposition of existing petroleum-based plastics. Minimizing plastic buildup and reducing environmental impact throughout the entire process, from raw materials to reprocessed materials. Various studies are being conducted to achieve this.

[0005] Polymers containing ester functional groups undergo depolymerization. Monomerization is possible through this process, and various chemical reaction pathways have been developed. The monomers produced theoretically possess properties equivalent to those of the raw materials used in the initial polymer synthesis. This is possible. The depolymerization process is being applied to industrially recycle polyester. The pathways include hydrolysis and glycolysis. ), methanolysis, ammonolysis These include (is), and by combining them, we can arrive at a composite process that utilizes only the advantages of each process. Therefore, various chemical depolymerization methods are widely used.

[0006] The depolymerization methods for polymers containing the ester functional groups listed above will be explained in more detail. First, in the case of hydrolysis, various reaction pathways are used in the presence of acids, bases, and metal salt catalysts. Decomposition is known to occur. In the case of acid-catalyzed reactions, to obtain a high reaction yield... A very high concentration sulfuric acid solution is required, raising economic concerns regarding process design, operation, and post-treatment. The title and other issues are pointed out as drawbacks. When using base and metal salt catalysts, the decomposition reaction rate is This process is inefficient because it is very slow, results in low product purity, and makes catalyst recovery difficult. It is.

[0007] The methanolysis process is now used not only by global chemical companies but also by small and medium-sized plastics companies. up to now, it is one of the processes that has been widely applied in actual commercial processes. However, since methanol is used as a reaction solvent, harsh reaction conditions of high temperature and high pressure are required, which not only increases the equipment design cost, but also necessitates additional unit processes for reactant recovery and product purification, thus requiring high investment costs. To carry out efficient methanolysis, a transesterification catalyst is required. Examples of catalysts commonly used in the depolymerization reaction of polymers containing ester functional groups include those containing metals as cations, such as zinc acetate, magnesium acetate, cobalt acetate, and lead dioxide. However, the constituent metals of the catalyst may remain in the obtained depolymerized product, and depending on the application and purpose of the material to be repolymerized, to minimize the impact on human health hazards and product quality, the type and amount of catalyst used may be subject to constraints that need to be considered along with the efficiency and economic performance of the reaction and purification processes.

[0008] Hydrolysis and methanolysis processes are utilized in many fields, but both reactions are limited by the quality and yield of products generated during the decomposition of polyester resins, and have long decomposition reaction times. As decomposition products, only one of terephthalic acid (TPA) or dimethyl terephthalate (DMT) is produced as the main product, while terephthalate compounds of other forms are treated as by-produced impurities, so to resynthesize the produced product into a high-quality polymer material, a purification process with excessive energy consumption may be required.

[0009] Glycolysis is a depolymerization reaction in which glycol is added as a reactant. The most common example of glycolysis is using an excess of ethylene glycol (EG), which is one of the monomer raw materials ​​A process to produce bis(2-hydroxyethyl) terephthalate (BHET) by adding excess material. There is. Because ethylene glycol, which is part of the PET raw material, is used as a reactant, the reaction It has high thermodynamic miscibility with the product and allows for modification of existing polymerization processes with only minimal capital investment. It can be used as is, and has the advantage of being directly applied to production without separate chemical processing. There is. Glycolysis is generally carried out under reflux conditions of the reactant glycol. Furthermore, the rate of polymer degradation is slow, and even in the reaction equilibrium state, the product distribution is wide, so the reaction yield of the product is low. There may be limits not only to the rate but also to the production yield, and the final product, monomer, may be converted High-cost purification processes may be essential to achieve high-yield and high-purity separation from the target substance. The reaction catalyst used is from Korean Published Patent Publication No. 2012-01228480, Korea. As disclosed in Patent No. 1142328 and others, zinc acetate or lithium acetate is generally used. Such metal salt catalysts may not be completely removed during the purification process and may remain in the product. Because even small amounts of metals harmful to the human body may be present in the recycled monomer, Products produced using this material, particularly food ingredients, medical ingredients, and other materials that require non-toxicity, are produced using this material. It has the drawback of not being suitable as a raw material for reprocessing into household goods and other items. While the lysis reaction takes place at high temperatures, the product recovery and purification process is carried out using a low-temperature recrystallization method. This is generally the case, so energy consumption is high, and the method of supplying heat sources in the production process is also cost This has the problem of lower efficiency.

[0010] The glycolysis reaction described above can be carried out at low temperatures, and If environmentally friendly catalyst systems with low toxicity can be applied, not only will it lead to efficient and economical operation, but also Using polymers containing ester functional groups that are released in large quantities, the quality and use of the product are restricted. We anticipate that it can be efficiently utilized in the production of environmentally friendly raw materials that do not contain harmful substances.

[0011] On the other hand, monomers produced by chemical decomposition such as the aforementioned depolymerization are theoretically the initial It can be manufactured with properties equivalent to those of raw materials used in polymer synthesis, or with a purity suitable for use in polymer polymerization. However, the waste polymer material discharged after use contains various forms of foreign matter, which is the most It can provide the biggest cause of the deterioration of the final product's quality.

[0012] In particular, dye compounds that induce direct penetration into polymer substrates, such as dyes and pigments, decolorize This includes not only the design of materials to prevent this, but also a series of physical and chemical pre- and post-treatment and coloring processes. Because the product is manufactured through this process, it is difficult to remove with simple washing processes alone, and the depolymerization reaction Even in the resulting products, i.e., low-molecular-weight compounds containing the terephthalic acid structure, these compounds are chemically processed. It is not easy to isolate or separate them precisely.

[0013] Pigments are used by being dispersed in a solvent in the form of powder particles, and they have the property of being insoluble in water and oil. Dyes are pigments that dissolve uniformly in most solvents, and have very small particle sizes. They can exist in molecular form. Most pigments are incorporated into polymer resins by painting or printing methods. Introduced, dyes are applied to the dyeing process and are primarily used for dyeing textiles and leather. Furthermore, dyes include natural dyes obtained from plants, animals, or minerals, and artificially synthesized dyes. They are classified as industrial dyes. Artificial dyes include direct dyes, mordant dyes, reducing dyes, and color-developing dyes. Examples include dispersible dyes and reactive dyes, and polymer materials containing ester functional groups. In the case of dyes primarily used in this field, they are classified by their chemical structure into azo dyes and anthraquinone dyes. Disperse dyes are the most commonly used.

[0014] When purifying the depolymerization reaction product of a polymer containing an ester functional group to obtain a high addition monomer, Prior art for obtaining high-purity monomers with the pigment removed includes activated carbon, etc. Adsorption methods using adsorbents, physical separation methods such as filtration and distillation, oxidation, reduction, hydrolysis, electrolysis Chemical methods such as gas decomposition are being applied. However, even trace amounts of pigment compounds When it remains in the product, it exhibits coloration and its coloring properties, such as forming complexes with high-molecular-weight monomers, contribute to its effect. However, the separation process is often very fragmented. Furthermore, the cost of materials and energy used in the separation process is excessive. There is a risk of excessive costs, and ensuring economic viability is extremely difficult for most of them.

[0015] Related prior art includes Japanese Patent No. 4537288, which describes a dye extraction process and a solid-liquid separation process. The process includes a depolymerization reaction step, a transesterification reaction step, and an active ingredient recovery step, and dye-colored polyester This document discloses a method for producing dimethyl terephthalate and alkylene glycol from terephthalate fibers. This patent describes xyl as an extraction solvent for extracting dye from dyed polyester fibers. Using ylene and alkylene glycol, the glass transition temperature of the polyester is 220°C or higher. This method involves extracting and removing dyes at temperatures below ℃, where the dye is extracted beforehand before depolymerization. The resulting polyester fibers are subjected to depolymerization in the presence of an alkylene glycol and a portion of the polymer. By adding the reaction solution and initiating a depolymerization reaction, the bis-ω-hydroxyalkyl The document discloses a process for obtaining a depolymerization solution containing terephthalate (BHAT). However, Extracting dyes before depolymerization is undesirable because it is uneconomical and has low extraction efficiency.

[0016] Furthermore, Korean Patent No. 10-1142329 describes how it is obtained by depolymerization of polyester. The oligomer solution is brought into contact with an ion exchange resin to remove the catalyst in the oligomer solution, and the above The oligomer solution from which the catalyst has been removed is passed through a decolorizing agent such as activated carbon, activated clay, or diatomaceous earth. The present invention discloses a technique for removing colored substances from a sesame solution by adsorbing them with a decolorizing agent. However, This patent addresses the possibility of excessive use of decolorizing agents and limitations in the regeneration of adsorbents. It's not economical.

[0017] To solve these problems, we developed a method using the depolymerization of colored polymers containing ester functional groups. Colored dyes or pigments are derived from terephthalate derivatives produced during the manufacturing process or generated during the refining of the product. A substance that can effectively remove waste and prevent excessive energy consumption. Alternatively, process development may be required. [Overview of the Initiative] [Problems that the invention aims to solve]

[0018] In this invention, when a polymer containing an ester functional group is decomposed, the monomer produced is Impurities equivalent to or very low in the initial raw materials produced before polymerization or in existing petrochemical processes. The amount of substances can be adjusted. Furthermore, the present invention relates to waste discharged after consumption. The polymer can be used as a raw material for depolymerization, and the monomer produced from it also undergoes additional pretreatment. Because it can be reused in the same process shortly thereafter, it can contribute to achieving a circular economy for plastics. This invention aims to provide a method for producing high-quality recycled monomers using glycolysis.

[0019] Furthermore, this invention enables depolymerization under reaction conditions at much lower temperatures compared to conventional high-temperature reaction conditions. Therefore, we aim to provide a depolymerization method that can significantly reduce energy consumption. do.

[0020] Furthermore, the present invention provides reaction materials, reaction pathways, and systems that are more environmentally friendly than existing processes. This enables the formation of the product, and also facilitates the purification process of products depolymerized from polymers containing ester functional groups. The aim is to provide a simple, economical, and efficient monomer production method compared to other reaction technologies. ru.

[0021] On the other hand, the present invention adds to a polymer monomer containing an ester functional group, An extractant capable of selectively extracting and removing color-producing foreign substances present in a substance, and using the same The aim is to provide a purification method for purifying monomers of polymers containing ester functional groups.

[0022] Furthermore, the present invention relates to a reactant produced from a depolymerization reaction of the monomer of the polymer, or a purified To enable the production of monomers of the same quality as those before polymerization from the monomer mixture generated during the process. Furthermore, purification is performed in situ using the same process used for the depolymerization reaction. Alternatively, the aim is to provide a method for refining the product by adding one or more post-processing steps.

[0023] Furthermore, the present invention involves adding a small amount of additive and continuously applying the extraction process repeatedly. Furthermore, the purity of the polymer can be adjusted using high-purity monomers or derivative compounds of the polymer. We aim to provide a manufacturing method. [Means for solving the problem]

[0024] To solve the above problems, the present invention provides (1) one or more polyhydric alcohols, (2) (3) A mixture containing a conversion esterification reaction catalyst and a compound represented by the following chemical formula 1, By contacting a polymer containing an ester functional group, the polymer containing the ester functional group is obtained. A method for depolymerizing polymers containing ester functional groups, characterized by decomposing the polymer. provide.

[0025] [Chemical formula 1] TIFF0007943882000001.tif1750

[0026] In the formula, the substituent R1 is hydrogen, a hydroxyl group, an aldehyde group, a carboxyl group, or C1 ~C6 alkyl groups, C4~C6 cycloalkyl groups and C6~C 12 Among the aryl groups It is one of the following, and n is one integer from 0 to 5. If n is 2 or more, R1 may be the same or different, and the substituent R 2 is C1~C 10 It is an alkyl group, and the aforementioned m is an integer from 1 to 6. If m is 2 or greater, -O and R2 may be the same or different.

[0027] In one embodiment of the present invention, the exchange esterification reaction catalyst is a member of Group 1A, Group 2A, and It may contain one or more metal salts selected from Group 2B metals.

[0028] In one embodiment of the present invention, the counter-ion of the metal salt is It is composed of organic anions selected from carbonic acid, bicarbonate, alkoxide, or acetate. Shut up.

[0029] In one embodiment of the present invention, the polyhydric alcohol is ethylene glycol, diethylene Glycol, triethylene glycol, propylene glycol, dipropylene glycol L, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentane Diol, 1,6-hexanediol, 1,7-octanediol, 1,9-nonandiol , neopentyl glycol, 1,4-cyclohexanediol, isosorbide, and It may also be one or more selected from 1,4-cyclohexanedimethanol.

[0030] In one embodiment of the present invention, the polymer containing an ester functional group is polyethylene tere Phthalates (PET), polypropylene terephthalates (PPT), polyglycols or Polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), Dihydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene Adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate) Acid-co-3-hydroxyvaleric acid (PHBV), polybutylene terephthalate (PBT) ), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN) It may be one or more species selected from the group consisting of and vectran.

[0031] In one embodiment of the present invention, the compound represented by chemical formula 1 is methoxybenzene, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene n, 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 1,3, 5-trimethoxybenzene, 1,2,3,4-tetramethoxybenzene, 1,2,3,5 -Tetramethoxybenzene, 1,2,4,5-Tetramethoxybenzene, 2-Methoxybenzene Enol, 1,3-dimethoxy-2-hydroxybenzene, 4-hydroxy-3,5-di Methoxybenzoic acid, 3-(4-hydroxy-3,5-dimethoxyphenyl)prop-2- Enal, 4-hydroxy-3,5-dimethoxybenzaldehyde, 4-hydroxy-3, 5-Dimethoxyacetophenone, 3-(4-Hydroxy-3,5-Dimethoxyphenyl Lop-2-enoic acid, 4-enyl-2,6-dimethoxyphenol, 4-hydroxy-3- Methoxybenzaldehyde, 3-hydroxy-4-methoxybenzaldehyde, 2-Hyd Roxy-3-methoxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde 2-hydroxy-4-methoxybenzaldehyde, 3,4-dihydroxybenzaldehyde Dehyde, 1-methoxy-4-[(E)-prop-1-enyl]benzene, 1-bromo-4 - Methoxybenzene, 2-tert-butyl-4-methoxyphenol, ethoxybenzene 1,3,5-trichloro-2-methoxybenzene, 1,3,5-tribromo-2-methylbenzene Toxybenzene, 4-(prop-2-en-1-yl)phenol, 1-methoxy-4( (prop-2-en-1-yl)benzene, 5-(prop-2-en-1-yl)-2H- 1,3-Benzodioxole, 4-Methoxy-2-[(E)-Prop-1-yl]pheno Selected from the group consisting of yl and 2-methoxy-4-(prop-1-en-yl)phenol. It may be one or more of the above.

[0032] Furthermore, the present invention relates to a polymer depolymerization composition containing an ester functional group, and (A)1 (B) a polyhydric alcohol of type 1 or more, (C) a catalyst for exchange esterification, and (D) the same as shown in Chemical Formula 1. The present invention provides a composition containing the compound.

[0033] The catalyst for the exchange esterification reaction is a metal-free organic compound catalyst or a Group 1A, Group 2A catalyst. It may also be one or more metal salts selected from Group 2B.

[0034] The amount of polyhydric alcohol contained in the above composition is per molar repeating unit of the polymer to be depolymerized. The ratio of moles from 1 to 50, the amount of exchange esterification reaction catalyst, and the amount of polymer to be depolymerized The ratio of moles per unit mole from 0.001 to 1, and the amount of the compound represented by chemical formula 1, The ratio of moles per repeating unit mole of the polymer to be depolymerized is between 0.001 and 50. It may also be a mixture of these.

[0035] Furthermore, the present invention relates to the purification of glycol addition monomers obtained by the depolymerization method of the present invention. Provide a method.

[0036] The purification method described above involves (1) removing the compound represented by Chemical 1 from the depolymerization reaction product in gas-liquid form. (1) Separation by separation or liquid-liquid extraction, and (2) After step (1), unreacted ester A solid separation step of separating a solid containing a polymer containing a functional group, and (3) the above (2) After separating the solids in the first stage, a recovery step is taken in which glycol-added monomers are recrystallized and recovered. include.

[0037] In one embodiment of the present invention, the purification method is a solid containing unreacted ester functional groups. The substance can be separated using physical filtration, and the glycol addition in step (3) above can be performed. The step of separating the oligomers can be performed before the recrystallization of the monomers.

[0038] On the other hand, the present invention removes color-producing foreign substances from monomers of polymer resins containing ester functional groups. An extractant for removing, characterized by containing a compound represented by the chemical formula 1, Extractor for removing color-producing impurities from monomers of polymer resins containing ester functional groups. To provide.

[0039] In one embodiment of the present invention, the monomer of the polymer resin containing the ester functional group is It is characterized by being obtained from the depolymerization reaction of a polymer resin containing an ester functional group. It can be done this way.

[0040] Furthermore, the present invention removes foreign matter from monomers of polymer resins containing ester functional groups. A purification method for producing high-purity monomers, wherein 1) an aesthetic treatment containing color-producing foreign matter A polymer monomer containing a functional group is mixed with the compound represented by the chemical formula 1. 1) The step of letting the mixture from step 1) stand to induce liquid-liquid phase separation, and 2) the step of letting the mixture from step 1) stand to induce liquid-liquid phase separation, and 3) The steps include separating and discharging the phase-separated liquid-liquid layers into an upper organic solution layer and a lower aqueous solution layer, High purity is obtained by removing color-producing impurities from polymer monomers containing ester functional groups. This invention provides a purification method for producing monomers.

[0041] In another embodiment of the purification method of the present invention, in step 1) above, the chemical formula represented by chemical formula 1 is used In addition to the compound, a hydrophilic liquid or water that cannot be mixed with the compound represented by chemical formula 1 is used to distinguish the color development. It can be characterized by being added to a monomer containing a substance.

[0042] In another embodiment of the purification method of the present invention, the monomer contains an ester functional group. The reaction product obtained from the depolymerization of the polymer, or the mixture after the depolymerization reaction. It can be characterized as being partially purified.

[0043] Furthermore, in the purification method according to the present invention, the separated aqueous solution layer is represented by chemical formula 1 The step of adding the compound and further extracting the color-producing foreign substance is repeated one or more times. This process is completed, and the separated organic solution layer contains a hydrophilic liquid that cannot be mixed with the compound represented by chemical formula 1. Alternatively, the process may further include the step of adding more water and mixing, followed by another phase separation.

[0044] In the purification method according to the present invention, the separated aqueous solution phase is recrystallized to produce S The step of recovering monomers of a polymer resin containing tel functional groups may further be included. .

[0045] Furthermore, the present invention relates to (a) a colored polymer containing an ester functional group, and the chemical formula 1 above. (b) a step of adding a compound, and (b) a step of depolymerizing the polymer containing the ester functional group. (c) The depolymerization reaction product obtained from the above depolymerization reaction is mixed with a compound represented by chemical formula 1 and (d) the step of adding an immiscible hydrophilic solution or water and mixing, and (c) the mixed liquid from step (c) (e) Allowing the liquid to stand to induce liquid-liquid phase separation, and (f) the phase-separated liquid-liquid layer is used as the upper phase The process includes the step of separating and discharging the liquid phase into a lower aqueous phase and an aqueous phase below, and contains an ester functional group. High-purity monomers are obtained by removing color-producing impurities from monomers obtained through the depolymerization of color polymers. This provides a purification method for producing [the product].

[0046] Furthermore, in another embodiment of the present invention, from the organic solution layer separated and discharged in step (e) This method can be characterized by recovering organic solvents through distillation and recycling them. [Effects of the Invention]

[0047] According to the present invention's method for depolymerizing polymers containing ester functional groups, Glycol-added monomers are raw materials for polymers before production or for polymer resynthesis. - (e.g., bis(2-hydroxyethyl) terephthalate)) can be produced in high yield and high purity. It is possible to do so, and the polymer discharged after use is polyethylene terephthalate ( Poly(ethyleneterephthalate, PET) and waste polyester Using fibers as a raw material, high-purity bis(2-hydroxyethyl) terephthalate (bi Regeneration of s(2-hydroxyethyl)terephthalte (BHET), etc. This can be usefully utilized in the large-scale production of monomers.

[0048] According to the present invention, reaction conditions are more relaxed compared to existing reaction conditions, and environmentally friendly elements are used. This reaction system, composed of materials, is applied to the production of glycolysis-based depolymerization monomers. By doing so, the reactivity of polymers containing ester functional groups to decomposition, and the target mo Selectivity for the nomer can be ensured simultaneously, and after the reaction, many of the materials containing the catalyst are Since thermodynamic phase separation methods such as liquid-liquid extraction and gas-liquid separation can all be effectively applied, recovery is also easy. Therefore, the amount of impurities in the decomposition products can be significantly reduced.

[0049] Furthermore, the present invention uses a lower temperature and a larger size compared to the glycolysis process reported in existing prior art literature. High yield and high purity glycol-added monomers can be obtained even under pressure.

[0050] Furthermore, the selection of catalysts applicable to the technology according to the present invention is extremely diverse, and conventionally used Since it is possible to use inexpensive catalysts that are less toxic than commercially available catalysts (for example, zinc acetate), It is possible to produce products that are harmless to the human body, as well as environmentally friendly and economical products. be.

[0051] The monomers depolymerized by the technology according to the present invention can be polymerized to form plastics and resin products. Because there are no restrictions on quality or use when reused as a raw material, complete chemical recycling technology is possible. The technique is feasible.

[0052] On the other hand, according to the extractant and purification method of the present invention, the monopolymer containing ester functional groups It is possible to purify the mer to a high degree of purity.

[0053] Furthermore, the monomer of the polymer is obtained by depolymerization of a colored polymer containing an ester functional group. The result is a depolymerized monomer of equivalent quality to that of the polymer before production, This makes it possible to produce addition monomers (e.g., BHET) in high yield and high purity.

[0054] Furthermore, since the extractant does not participate in the depolymerization reaction, the monomer purification process after the depolymerization reaction is not performed. It can be used directly without separation, and can be added to a step before or after the depolymerization reaction, It offers high efficiency and ease of driving.

[0055] Furthermore, the extractant reduces the hydrogen bonding force between foreign substances and additives, and the π- between aromatic rings of different compounds. The affinity with the depolymerized low-molecular-weight compound is regulated by the adjustment of non-covalent mutual attractive forces such as overlap. The force can be reduced, and the freed pigment compound enters the organic phase, becoming the terephthalate compound, which is the product. Since the substance is distributed in high concentration in the hydrophilic lower phase, physical phase separation allows for high purity of the product. It can be purified by converting the reaction step after the depolymerization reaction itself into a purification step, or by continuing Because it is possible to implement a series-type process using flow, the process configuration can be simplified. This has the advantage of being able to reduce energy consumption.

[0056] This invention allows for the application of more relaxed operating conditions compared to existing separation processes, and energy This allows for minimizing ghee loss and uses compounds made from environmentally friendly materials. The process is applied to separate some or all of the extractants and compounds used in the reaction. Because it can be recovered and reused, it enables an environmentally friendly and economical refining process. It is possible.

[0057] Furthermore, the extractant and purification method of the present invention do not require complex process units and involve simple, repetitive phases. Using separation methods can increase the purity of the depolymerized product, thus allowing for a variety of forms and methods. This can be applied to purification techniques for high purity and high yield. [Brief explanation of the drawing]

[0058] [Figure 1] This is the 1H-NMR spectrum of BHET obtained from PET depolymerization using one comparative example of the present invention. [Figure 2] This is the 1H-NMR spectrum of a sample obtained by repeatedly washing with water several times the BHET obtained from PET depolymerization according to one comparative example of the present invention. [Figure 3] This is the 1H-NMR spectrum of BHET obtained from PET depolymerization according to one embodiment of the present invention. [Figure 4] This shows the liquid-liquid phase equilibrium diagram (Tx) of a two-component compound consisting of anisole, a type of extractant according to the present invention, and a hydrophilic solvent (water or ethylene glycol). [Figure 5]These are the 1H-NMR spectra of organic pigments extracted during the depolymerization and product purification process of colored waste PET polymers in some comparative examples and examples of the present invention, and the purified depolymerized monomer products. [Figure 6] These are the 1H-NMR spectra of organic dyes extracted during the depolymerization and product purification process of colored polyester fibers in some embodiments of the present invention, and the purified depolymerized monomer products. [Modes for carrying out the invention]

[0059] Unless otherwise defined, all technical and scientific terms used herein refer to the present invention. It has the same meaning as it would normally be understood by a skilled expert in the relevant technical field. In general, the nomenclature used herein is well known and commonly used in the art. It is.

[0060] Throughout this specification, when a part "includes" a certain component, this means in particular Unless otherwise stated, it includes other components rather than excluding them. It means that it is possible.

[0061] The present invention relates to (A) one or more polyhydric alcohols, (B) an exchange esterification reaction catalyst, and ( C) A mixture containing the compound represented by the following chemical formula 1, the high-molecular-weight compound containing the ester functional group. The polymer containing the ester functional group is depolymerized by contacting it with the child. The present invention provides a method for depolymerizing polymers containing ester functional groups, as a characteristic feature.

[0062] Furthermore, the present invention relates to a polymer depolymerization composition containing an ester functional group, and (A)1 (B) a polyhydric alcohol of type (A), a catalyst for exchange esterification, and (C) represented by the following chemical formula 1. A polymer depolymerization composition containing an ester functional group, characterized by containing a compound that is subjected to the following action. To provide.

[0063] The present invention uses one or more polyhydric alcohols as raw materials for the glycolysis reaction. Existing catalysts such as zinc acetate may be used as the catalyst, but Group 1A, Group 2A or 2 Group B metal cations and carbonic acid, bicarbonate, and aluminum as counterions. Salts consisting of organic anions such as coxides or acetates can also be used as catalysts, and metal-containing Non-metallic organic compound catalysts composed of rare organic substances can also be used.

[0064] Furthermore, the present invention involves adding a compound represented by the following chemical formula 1 as an additive to form an ester vessel. Activity of the depolymerization reaction for converting polymer raw materials containing active groups into glycol-added monomers. The energy required for activation can be significantly reduced, and as mentioned earlier, this applies not only to Group 2B but also to Group 1A and 2B. Low-value catalysts containing various forms of metals such as Group A, or organic catalysts that decompose at high temperatures, react. Since it can be selected as a material, economic efficiency can be ensured through the reuse and recovery of materials, and impurities can be controlled. It is easy. Therefore, the present invention can maintain high depolymerization reactivity at low temperatures. Furthermore, it is characterized by improving the purity, yield, and reaction selectivity of the depolymerized monomer. .

[0065] [Chemical formula 1] TIFF0007943882000002.tif1750

[0066] In the formula, the substituent R1 is hydrogen, a hydroxyl group, an aldehyde group, a carboxyl group, or C1 ~C6 alkyl groups, C4~C6 cycloalkyl groups and C6~C 12 Among the aryl groups It is one of the following, and n is one integer from 0 to 5. If n is 2 or more, R1 may be the same or different, and the substituent R 2 is C1~C 10 It is an alkyl group, and the aforementioned m is an integer from 1 to 6. If m is 2 or greater, -O and R2 may be the same or different.

[0067] The depolymerization method of the present invention is useful for the depolymerization of polymers containing ester functional groups, and here Therefore, polymers containing ester functional groups can be found in the form of waste plastics, either alone or in mixtures, for example. Polyethylene, high-density polyethylene, low-density polyethylene, polypropylene, or combination thereof. The combination may be in the form of a polymer containing the ester functional group. Other polymers to be mixed with the polymers containing the ester functional groups listed as examples are: This is merely a simple example and is not limited to those listed.

[0068] Furthermore, polymers containing ester functional groups undergo condensation polymerization of dicarboxylic acids and dialcohols. It may also be a polymer formed by, where the dicarboxylic acid is terephthalic acid, naphthalic acid Diphenyl dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl Sulfonide dicarboxylic acid, diphenoxyethane dicarboxylic acid, succinic acid, adipic acid, Bacic acid, azeraic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, trimellitic acid A dialcohol is selected from the group consisting of pyromellitic acids and combinations thereof, and the dialcohol is E Tylene glycol, trimethylene glycol, 1,2-propanediol, tetramethyl Neopentyl glycol, hexamethylene glycol, decamethylene glycol Recall, dodecamethylene glycol, 1,4-cyclohexanedimethanol, diethylene Glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol Coal, dipropylene glycol, tripropylene glycol, tetrapropylene glycol Polypropylene glycol, di(tetramethylene) glycol, tri(tetramethylene) Polytetramethylene glycol, pentaerythritol, 2,2- (4-β-hydroxyethoxyphenyl)propane and combinations thereof Selected from the group.

[0069] For example, the polymer containing the ester functional group is polyethylene terephthalate (P ET), polypropylene terephthalate (PPT), polyglycol or polyglycol Acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxya Lucanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (P EA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3- Hydroxyvaleric acid (PHBV), polybutylene terephthalate (PBT), polytrim Teylene terephthalate (PTT), polyethylene naphthalate (PEN), Vectran ( You can choose from Vectran, or any combination thereof.

[0070] One of the most common examples of polymers containing the aforementioned ester functional group is polyethylene tereph It is a talate, and in this case, the starting material for the polymer production is terephthalic acid or its These are derived monomers and ethylene glycol.

[0071] The polymers containing ester functional groups used in this invention are not in a pure state, but rather in various forms. It may contain impurities. For example, in addition to polymers containing ester functional groups, This includes bottle caps, adhesive, paper, residual liquid, dust, or any combination thereof. A mixture of unspecified residues can be used as raw materials for depolymerization.

[0072] According to the present invention, a method for depolymerizing a polymer containing an ester functional group is the ester The polymer containing functional groups can be included in the reaction raw materials at a concentration of approximately 0.1% to 70% by mass. It is possible. If an amount less than 0.1% by mass is initially introduced, it becomes difficult to ensure economic viability, 7 If an amount greater than 0% by mass is added, mass transfer is restricted and the reaction rate becomes significantly lower. This could lead to the following problem.

[0073] The polyhydric alcohol for glycolysis depolymerization of the polymer containing the ester functional group is , a compound having at least two alcohol functional groups, more specifically, a secondary direct This includes, but is not limited to, compounds having two or more hydroxyl groups, such as chain-type alcohols. do not have.

[0074] The polyhydric alcohol is in a ratio of 1 to 50 moles per repeating unit mole of the polymer. It can be used within a certain range.

[0075] An example of a polyhydric alcohol having at least two alcoholic functional groups according to the present invention is eth Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol L, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3- Methyl-1,5-pentanediol, 1,6-hexanediol, 1,7-octanedio ol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanedi ol, isosorbide, 1,4-cyclohexanedimethanol and the like, one or more selected from the group consisting of may be used.

[0076] As the transesterification reaction catalyst according to the present invention, a catalyst in the form of an organic substance containing no metal can be used . Non-limiting examples of the catalyst in the organic substance form include linear amines (e.g., ethylene diamine, diethylenetriamine, tris(2-aminoethyl)amine, tetraethylene pentamine), amides (e.g., acetamide), guanidines (e.g., triazabi cyclodecene), imidazoles (e.g., 2-ethyl-4-methylimidazole), ureas (e.g., urea, 1,1-dimethylurea, 1,3-dimethylurea), aromatic amines (e.g., benzenedimethanamine) and cycloalkylamines (e.g., cyclohexy lmethylamine, dimethylcyclohexylamine), and it is preferable that the compound constituting the catalyst itself does not directly participate in the reaction.

[0077] As another example of the catalyst according to the present invention, a salt constituted by a Group 1A, Group 2A or Group 2B metal cation and an anion selected from carbonic acid, bicarbonate, alkoxide or acetate as a counter-ion may be mentioned.

[0078] Examples of the Group 1A ion used as the catalyst include lithium (Li + ), sodium (N a + ), potassium (K + ), Group 2A metal magnesium (Mg 2+ ), calcium (Ca 2 + ​​​) is one of the Group 2B metals, and zinc (Zn 2+ ) and others are possible, but there are no particular limitations. stomach.

[0079] The amount of the catalyst is the ratio of 0.001 to 1 mole per repeating unit mole of the polymer. Preferably, it can be used in a ratio range of 0.01 to 0.1 moles per unit mole. .

[0080] The compound represented by the above chemical formula 1 has the depolymerization reactivity of polymers containing ester functional groups. It is used as an additive during depolymerization reactions to increase the selectivity for high-quality and useful products. As an example, the substituent R2 is C1~C 10 alkyl groups, preferably C1-C6 alkyl groups The group may be a lucyl group, more preferably a C1-C3 alkyl group.

[0081] In one embodiment of the present invention, the compound represented by chemical formula 1 contained in the additive is Methoxybenzene, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4 -Dimethoxybenzene, 1,2,3-trimethoxybenzene, 1,2,4-trimethoxy Benzene, 1,3,5-trimethoxybenzene, 1,2,3,4-tetramethoxybenzene 1,2,3,5-tetramethoxybenzene, 1,2,4,5-tetramethoxybenzene , 2-methoxyphenol, 1,3-dimethoxy-2-hydroxybenzene, 4-Hyd Roxy-3,5-dimethoxybenzoic acid, 3-(4-hydroxy-3,5-dimethoxybenzoic acid) Nyl)prop-2-enal, 4-hydroxy-3,5-dimethoxybenzaldehyde, 4 -Hydroxy-3,5-dimethoxyacetophenone, 3-(4-Hydroxy-3,5-di Methoxyphenylprop-2-enoic acid, 4-enyl-2,6-dimethoxyphenol, 4 -Hydroxy-3-methoxybenzaldehyde, 3-hydroxy-4-methoxybenzaldehyde Ludehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxy-5-meth Xybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde, 3,4-dihy Droxybenzaldehyde, 1-Methoxy-4-[(E)-Prop-1-enyl]benz (1-metoxy-4-[(E)-prop-1-enyl]benzene; 1-methoxy-4-[(E)-prop-1-enyl]benzene Zen), 1-bromo-4-methoxybenzene, 2-tert-butyl-4-methoxybenzene Nol, ethoxybenzene, 1,3,5-trichloro-2-methoxybenzene, 1,3, 5-Tribromo-2-methoxybenzene, 4-(prop-2-en-1-yl)pheno (4-[prop-2-enyl]phenol; 4-[prop-2-enyl]phenol), 1-methoxy-4(prop 1-metoxy-4-[prop-2-en-1-yl]benzene; 1-methoxy C-4-[prop-1-en-1-yl]benzene), 5-(prop-2-en-1-yl)-2H -1,3-benzodioxole (5-[prop-2-en-1-yl]-2H-1,3-benzodioxole), 4-methoxy 4-metoxy-2-[(E)-prop-1-yl]phenol 4-Methoxy[prop-1-yl]phenol), and 2-Methoxy-4-(prop-1-yl)phenol 4-Methoxy-4-[prop-1-en-yl]phenol; 4-Methoxy[prop-1-en-yl]phenol Selected from a group consisting of naturally derived or synthesized compounds such as [phenol] It may be one or more types.

[0082] The amount of the additive is 0.001 to 50 moles per repeating unit mole of the polymer. It can be used in a ratio, preferably a ratio of 0.1 to 10 moles per repeating unit mole.

[0083] The polymer depolymerization method according to the present invention is performed at a temperature in the range of 100°C to 200°C, preferably 130°C. We propose a rapid method for depolymerizing polymers containing ester functional groups in the range of ~160°C. Provided in this application is a method for depolymerizing polymers containing ester functional groups. This method allows the reaction to take place at lower temperatures than conventional methods, thus achieving energy savings. Furthermore, the used catalyst and additives can be recovered and reused through a separate recovery process. Therefore, it is economical.

[0084] Furthermore, the polymer depolymerization method of the present invention can be carried out at atmospheric pressure, but the added This can also be done under pressure, depending on the vapor pressure formation of the agent or reactant.

[0085] In the method described herein, the depolymerization reaction time depends on the amount of polymer used. Although it can vary, depolymerization can occur within a reaction time of 0.5 to 12 hours. To minimize the yield of by-products, a reaction time of 0.5 to 4 hours is preferable.

[0086] After the reaction, a further step is taken to filter and remove any unreacted polymeric substances from the reaction mixture. It is possible.

[0087] The depolymerization of polymers containing ester functional groups according to the present invention is performed using polyhydric alcohols. This involves polymerization and can be considered a type of glycolysis-depolymerization reaction.

[0088] The method for purifying glycol-added monomers obtained by the depolymerization method according to the present invention is (1 ) The compound represented by chemical formula 1, which is an additive, is separated from the depolymerization reaction product by gas-liquid separation or liquid separation. - A step of separation using liquid extraction, and (2) after step (1) above, unreacted ester functional groups (3) A solid separation step in which solids containing polymers are separated, and (2) the solids from step (2) The process may include a recovery step in which the glycol-added monomer is recrystallized and recovered after the separation of the material. Cut.

[0089] The gas-liquid separation of the additive may be carried out separately from the reaction, but it is performed immediately after the reaction is complete. It may be used. For example, using a pre-installed condenser maintained at a low temperature, the vaporized additive Maintain a state in which the agent is condensed and refluxed into the reactor, and then raise the temperature after the reaction is complete or Maintain the current flow, but change the path for the additive that was condensing and refluxing from inside the reactor to outside. It can be separated.

[0090] Liquid-liquid extraction is a method of separation by adding water for the recovery and purification of the target product. When water is added, a clear phase separation boundary is formed, and when only the organic layer is separated at low temperature, a large portion The additives can be physically separated. The additives that may remain in the aqueous solution after separation are those that are concentrated in the water. If you increase the temperature or decrease it, it has very limited solubility, so it can be almost completely separated and recovered. This is possible. The majority of the product can be recovered through crystallization, and the purified product can be produced. Any trace amounts of additives that may remain in the material are dried by heating at 50-150°C, preferably under vacuum. It can be easily and completely removed by heating and drying below.

[0091] Gas-liquid phase separation for additive recovery by the method described herein may result in the loss of some or more of the additive. This involves a separate step of raising the temperature of the reactor after the reaction above the reaction temperature so that all of the reaction material vaporizes or volatilizes. The method includes setting up a step and separating the additive by distillation. Separation of the additive by liquid-liquid extraction is Using water may be the most economical option, but it induces additives and thermodynamically unstable phases. A hydrophilic substance can be used, which is a glycol or dihydrogen used as a reactant. All types are also acceptable.

[0092] The solid containing the polymer that has not yet reacted with the ester functional group is precipitated after the depolymerization reaction. Remove before or after the reaction is complete by various physical methods such as filtration, coagulation, flotation, and compression. This can be done, and it can be reintroduced into the depolymerization process. In the case of removal methods using filtration, the unreacted amount A filter with fine pores smaller than the particle size of the molecule can be used, and the flow of the filtered material can be improved. The rate of increase can be accelerated by simultaneously applying or removing pressure.

[0093] The method for recovering glycol-added monomers by the aforementioned recrystallization process removes unreacted substances from the reaction. It is even more preferable to perform this after removal, at a temperature above room temperature, for example, in the range of 60°C to 120°C. Preferably, water or a solvent necessary for the crystallization of the target product at a temperature in the range of 90°C to 110°C. Although a medium is used, this can also be done after adding a step of separating the oligomers by filtration. The filtrate can be maintained at a low temperature and recovered as a product through a recrystallization process. To adjust the concentration of impurities within the material, the process of physical separation and recrystallization is repeated. It is also possible to separate the oligomer before recrystallization of the glycol-added monomer in step (3) above. The first step can be performed first.

[0094] When constructing the reaction system using the depolymerization method of the present invention, a non-metallic catalyst may be used, Alternatively, a group 1A or group 2A metal cation and carbon as a counter-ion. Using a metal salt consisting of an organic anion such as an acid, bicarbonate, alkoxide, or acetate as a catalyst When used, any metal components that may remain in the purified monomer product are of low toxicity and are purified. Because the removal rate during the process is high, it is easy to control the concentration of impurities.

[0095] On the other hand, the present invention relates to the production of pigments and dyes from polymer monomers containing ester functional groups. An extractant for removing foreign substances, comprising the compound represented by the chemical formula 1. The present invention provides a characteristic extractant. The compound represented by chemical formula 1 has one or more aluminum atoms in an aromatic ring. The kill group is linked via a linker, which has at least one oxygen atom. ru.

[0096] An example of the compound represented by chemical formula 1, which is an extractant, is an additive for removing the foreign matter. Since it is identical to the compound represented by chemical formula 1 listed as an example within the formula, to prevent confusion To avoid repetition, duplicate entries have been omitted.

[0097] Furthermore, in one embodiment of the present invention, the monomer of the polymer containing the ester functional group This is obtained from the depolymerization reaction of a polymer containing an ester functional group, and in particular, the above A polymer containing an ester functional group may be a colored polymer, but is represented by the chemical formula 1 above. When the compound is added to a depolymerization reaction, it reacts with the depolymerization of polymers containing ester functional groups. Although they do not directly participate as a substance, their performance in terms of depolymerization reactivity and product selectivity is improved in low-temperature reactions. It also possesses the property of being able to maintain its properties, and after being mixed with the polymer before the depolymerization reaction, it depolymerizes. It can also be used in a form that involves combining.

[0098] The extractant according to the present invention extracts pigments and dyes from polymer monomers containing ester functional groups. It is useful as an extractant to remove color-producing foreign substances such as ester functional groups, and here it contains high The molecules are in the form of single or mixed waste plastics, such as polyethylene, high-density polyethylene N, low-density polyethylene, polypropylene, or a combination thereof, the ester functional It may be in a form mixed with a polymer containing the group. The above-mentioned S is listed as an example. Other polymers mixed with polymers containing tel functional groups are merely examples and are listed above. It is not limited to those listed.

[0099] Furthermore, the present invention removes impurities from polymer monomers containing ester functional groups to achieve high purity. This invention provides a purification method for producing monomers of a certain degree.

[0100] The purification method described above involves 1) a polymer monomer containing an ester functional group that contains color-producing foreign matter. - A step of adding and mixing the compound represented by the above chemical formula 1, and 2) the mixing in step 1) The steps are: 1) Allow the mixture to stand to induce liquid-liquid phase separation, and 2) Use the phase-separated liquid-liquid layer as the upper phase. The method is characterized by including the step of separating the organic solution layer into an organic solution layer and a lower aqueous solution layer.

[0101] The above step 1) is for extracting foreign substances from polymer monomers containing ester functional groups. At the stage where the extractant is added and mixed so that more foreign matter is distributed to the extractant, be.

[0102] The extraction partition temperature in step 1) above is the depolymerization temperature of a polymer containing a common ester functional group. After inducing phase separation at or below the reaction temperature without adding a hydrophilic solvent, extract Although the extraction process can be carried out, the dissolution of the substance represented by the chemical formula 1 is very limited. Adding an excess of water with a certain degree of concentration further clearly creates a phase separation boundary, resulting in the depolymerization product and foreign matter. By inducing an extremely asymmetrical distribution, monomers can be recovered in high purity.

[0103] The compound represented by the aforementioned chemical formula 1 is also relative to organic substances that produce color, such as dyes and pigments. Since it is a substance that has a high affinity for dyes and pigments, in step 1) above, The foreign matter migrates to the organic phase, which is mostly composed of the compound represented by chemical formula 1, and undergoes other hydrophobic processes. Compounds and monomer products are highly susceptible to mass transfer into the hydrophilic phase.

[0104] The temperature range during extraction and distribution in step 1) above can be between 25 and 150°C.

[0105] Removal of foreign substances such as dyes and pigments and purification of monomers by liquid-liquid extraction according to the present invention While using water may be the most economical option, it can induce additives and thermodynamically unstable phases. Hydrophilic substances that can be used as reactants can be used. These reactants can be reacted with without the addition of a separate solvent. This can also be carried out in the presence of polyhydric alcohols used in the process.

[0106] The above step 2) involves the liquid-liquid phase of the mixed liquid after asymmetric distribution of foreign matter and other substances has occurred due to mixing. This is the stage where separation occurs.

[0107] The aforementioned liquid-liquid phase separation is induced continuously or in batches using known means such as a decanter. Compositions that can be made such that phase separation occurs because the thermodynamic miscibility between them is sufficiently low. and temperature can be used. The composition and temperature that cause the phase separation to occur can be determined by a normal technician. Since the selection process is straightforward, detailed descriptions will be omitted.

[0108] As an example, Figure 4 shows anisole, one of the extractants according to the present invention, and a hydrophilic solvent (water). To distinguish between the thermodynamic states of a two-component compound composed of (or ethylene glycol) On the temperature-dependent liquid-liquid phase equilibrium curves determined by titration, according to one embodiment of the present invention The reaction conditions for the depolymerization and the purification conditions for the extraction are shown in a diagram. The x-axis represents the composition of the organic extractant anisole in mole fraction, and the y-axis represents the opposite. This indicates the appropriate temperature for phase separation. Refer to the diagram in Figure 1 for an appropriate composition for phase separation. The temperature can be selected.

[0109] The 3) step involves separating the mixture into an organic phase (organic solution layer) and an aqueous phase (aqueous solution layer) from the mixture after phase separation has occurred. This is the stage where each layer is separated and discharged. Separation is carried out using conventional means, and after separation The organic and aqueous phases can be individually post-treated to further increase the recovery rate of the target product. ru.

[0110] In another embodiment of the purification method of the present invention, the primary separation in step 3) above The organic solution layer (or organic phase) is composed mostly of the compound represented by the chemical formula 1, and water is added to it. Back-extraction is performed by adding a hydrophilic solvent to redistribute the small amount of monomer remaining in the organic phase. This process may then include a further step of additionally recovering monomer products.

[0111] Furthermore, from the organic phase separated and discharged by the liquid-liquid extraction according to the present invention, the chemical formula To recover the additive represented by 1 and separate the dye and pigment, gas-liquid separation is used. This may include methods such as distillation.

[0112] The monomer product concentrated in the separated and discharged aqueous solution layer undergoes crystallization, which removes most of the product. Trace amounts of additives that can be recovered and remain in the purified target product are 50-15 It can be easily and completely removed by heating and drying at 0°C, preferably under vacuum conditions. It is also possible to do so.

[0113] The monomer purification process for polymers containing ester functional groups according to the present invention removes some foreign matter. A process of theoretical filtration and separation / removal can be added or carried out in parallel.

[0114] In one embodiment of the present invention, the polymer containing the ester functional group in step 1) The nomer is a depolymerization reaction mixture obtained by depolymerizing the polymer containing the ester functional group. Alternatively, these may be derived compounds obtained from them, and these depolymerization reaction mixtures are The product is either in its unpurified state after the reaction, or it has undergone partial purification.

[0115] Thus, in the present invention, the monomer of the polymer containing the ester functional group in step 1) - a depolymerization reaction mixture obtained by depolymerizing the polymer containing the ester functional group, or If the compound is a derivative obtained from these, the addition of the extractant is necessary for the depolymerization reaction. This can be done in an earlier or later stage.

[0116] Polymers containing ester functional groups undergo depolymerization reactions to produce monomers, dimers, and oligomers. can be decomposed into low-molecular compounds and the like, and possible depolymerization reaction pathways include hydroly sis (hydrolysis), glycolysis, methanolysis( methanolysis), ammonolysis, and the like, and combinations of these combined complex processes can be utilized.

[0117] Specifically, the extractant is added at the pre-stage of the depolymerization reaction step to remove color-developing foreign matters in the depolymerization reaction mixture, and the method for purifying the monomer obtained from the depolymerization of the colored polymer containing ester functional groups with high purity comprises: (a) adding the compound of Chemical Formula 1 to the colored polymer containing ester functional groups to remove color-developing foreign matters, and the method for purifying with high purity the monomer obtained from the depolymerization of the colored polymer containing ester functional groups The method for purifying the monomer at high purity comprises: (a) adding the compound of Chemical Formula 1 to the colored polymer containing ester functional groups adding the compound of Chemical Formula 1, and (b) depolymerizing the polymer containing ester functional groups and (c) adding water or a hydrophilic solution that is immiscible with the compound represented by Chemical Formula 1 to the depolymerization reaction mixture obtained from the depolymerization reaction, and mixing the resulting mixture, and (d) allowing the mixed solution obtained in step (c) to stand still to induce liquid-liquid phase separation, and (e) separating and discharging the phase-separated liquid-liquid layers into an upper organic solution layer and a lower aqueous solution layer. adding a hydrophilic solution that is immiscible with the compound represented by Chemical Formula 1 and mixing, and (d) subjecting the mixture obtained in the step (c) to standing to induce liquid-liquid phase separation, and (e) separating and discharging the phase-separated liquid-liquid layers into an upper organic solution layer and a lower aqueous solution layer. and discharging the layer into an upper organic solution layer and a lower aqueous solution layer.

[0118] The process for purifying the depolymerized monomer of a colored polymer containing ester functional groups according to the present invention can additionally or concurrently perform a step of physically filtering unreacted polymer substances and some foreign substances from the depolymerization reaction mixture to separate and remove them. physically filtering unreacted polymer substances and some foreign matters from the polymerization reaction mixture to separate and remove them, and the step can be carried out additionally or in parallel. can be carried out additionally or in parallel.

[0119] The depolymerization of the polymer containing ester functional groups according to the present invention can be carried out in the presence or absence of a catalyst by addition of an alcohol, water or a hydroxide, and the subsequent transesterification reaction pathway to perform depolymerization. to be depolymerized.

[0120] Hereinafter, the details of the process of the present invention will be described through Examples, Comparative Examples and Experimental Examples. This is the representative illustration related to the present invention, and the scope of application of the present invention cannot be limited thereto .

[0121] 1. Method for depolymerizing polymer containing ester functional group [Raw Materials 1 to 4] A polymer substance containing an ester functional group, which is obtained by cutting PET bottles discharged after use to obtain single-layer plastic flakes having an area of 1 cm 2 or less and a thickness of 0.3 mm or less (Raw Material 1), and plastic flakes having an area of 1 cm 2 or less and a thickness of 0.8 to 1.2 mm (composed of 10 or more multilayers) (Raw Material 2) were prepared as raw materials. In addition, the colored label base of the PET bottles discharged after use was cut to obtain plastic pieces having an area of 1 cm 2 or less and a thickness of 0.1 mm or less (Raw Material 3), and waste fiber pieces obtained by cutting polyester fabric discharged after use to have an area of 1 cm or less and a thickness of 1 mm or 2 less ( Raw Material 4) were prepared as raw materials.

[0122] [Experimental Example 1: Depolymerization reaction step (no additive is added before the reaction)] About 10 g of the polymer raw material prepared from "Raw Material 1" was quantified as the raw material for the reaction. About 38.75 g of ethylene glycol, which is a polar solvent of dihydric alcohol (12 moles per 1 mole of the repeating unit of the polymer) was charged into a three-necked flask, a reflux condenser was attached at atmospheric pressure, and then the mixture was heated and stirred using a heating magnetic stirrer. When the temperature reached 177°C, 10 g of the polymer raw material was charged, followed by continuing to raise the temperature while stirring. The reaction mixture When the temperature reached 177°C, 10 g of the polymer raw material was charged, subsequently the temperature was raised while stirring at the same time. The reaction mixture When the substance reaches 197°C or reflux temperature, the catalyst is released at a concentration of 0 per mole of polymer repeating units. Only 0.4 moles were added, and the catalytic reaction was started. The reaction was carried out with continuous stirring for 2 hours. A condenser in which one end is exposed to atmospheric pressure while maintaining a constant temperature within a range of ±0.5°C. The reaction was carried out using [the specified method]. Unreacted substances in the product after the reaction were separated by filtration and quantified. The decomposed monomers, dimers, and by-reactants are mono(hydroxyethyl)terephthalates. Mono(hydroxyethyl)terephthalate, MHET And for oligomers, etc., high-performance liquid chromatography (H) was performed using standard samples. PLC, reversed-phase C18 column (250 mm, 5 micron), and UV detector (λ=25 The concentration was quantified using a 4nm (4nm) sample. For HPLC analysis, methanol was used as the mobile phase. A mixed solution with a water volume ratio of 70:30 is used while maintaining a constant flow rate of 0.7 mL / min. did.

[0123] [Experimental Example 2: Depolymerization Reaction Step (When Additives are Added Before the Reaction)] Before the depolymerization reaction begins, the additive is added at a rate of 4 moles per mole of repeating units of the polymer raw material. The amount was quantified, and this additive was added to ethylene glycol, a dihydric alcohol polar solvent, at approximately 38.7 Place 5g (12 moles per repeating polymer unit) into a three-necked flask and then into the air. After attaching a reflux condenser under pressure, the mixture was heated and stirred using a heated magnetic stirrer. When the temperature reaches 20°C below the final reaction temperature, 10g of polymer raw material is added, and the reaction continues to rise. The mixture was heated and stirred simultaneously. When the reaction mixture reached the reaction temperature, the catalyst was converted into polymer repeating units. The catalytic reaction was started by adding only 0.04 moles per unit. and the reaction temperature was maintained at a low temperature of 153°C or lower, the same method as in Experimental Example 1 was applied to carry out the reaction and analysis.

[0124] [Experimental Example 3: Product Purification Step] A 500 mL round-bottom flask was charged with the reaction product and 400 mL of distilled water, then the mixture was continuously stirred for about 1 hour within the range of 90 to 9 5°C. Oligomers in the post-reaction mixture were removed through filter paper (Whatman, pore diamete r: 3 microns) positioned in a filter by means of a vacuum pump. The temporarily obtained filtrate was filtered again with the same filter to separate and remove recrystallized oligomers and solids. The obtained filtrate was stored in a low-temperature bath maintained at 4 °C or lower for 16 hours or more to be crystallized, and then the precipitate was collected through a vacuum filtration apparatus, followed by drying in an oven maintained at about 80°C for 6 hours, and thereafter, the resulting white powder was quantified as a glycol addition product.

[0125] In order to confirm the residual metal content in the purified product, about 0.1 g of the purified product was pretreated by dissolving it in HNO3 and subjecting it to acid treatment, followed by ICP-AES (ICP atomic emission spectro metry; inductively coupled plasma-atomic emi ssion spectrometry) (model name: Thermo Fisher S cientific iCAP 6500Duo), and ICP-MS (ICP mass spectrometry; inductively coupled plasma-mass spectro metry) (model name: Thermo Fisher Scientific X S eries).

[0126] To understand the properties of the purified product, approximately 0.1g of the purified product was mixed with DMSO-d6 solvent. Prepare the sample by diluting it so that the monomer concentration is 6.25% by weight. 1 H-NMR ( 1 H nuclear magnetic resonance (Model name: Bruk er AVANCE II + The NMR spectrum was obtained via 500 MHz.

[0127] [Experimental Example 4: Additional Purification Step] The white powder obtained from Experimental Example 3 was placed in a 250 mL round-bottom flask containing 100 mL of distilled water. In addition, the mixture was stirred while maintaining a temperature of 90-95°C. After stirring for about 1 hour, the mixture was cooled to 4°C. The mixture is then transferred to a low-temperature chamber maintained below, and left for 16 hours or more to allow recrystallization to occur. The precipitate, after additional washing, was collected using the same filter used in Experimental Example 3. The resulting precipitate was dried in an oven maintained at approximately 80°C for 6 hours, and glycol was extracted. A white powder corresponding to the addition monomer was obtained. The powder product obtained by further purification is shown in the experimental example. ICP-AES, ICP-MS, and 1 1H-NMR analysis was performed.

[0128] [Calculation formula] Among the products obtained from depolymerization carried out according to the comparative examples and examples of the present invention, the solid phase is The unreacted product obtained was quantified by gravimetric analysis, and the product obtained in the liquid phase was diluted. The results were later quantified by HPLC analysis. From this, the conversion rate and product yield were calculated using the following formulas. It was calculated using this method.

[0129] Depolymerization rate of polymer depolymerization (%) = (Initial high molecular weight - Unreacted high molecular weight) / (Initial high molecular weight) × 100

[0130] Yield of monomer obtained by depolymerization (%) = (Number of moles of BHET obtained) / (Number of moles of terephthalate units in the input polymer structure) ) × 100

[0131] Yield of dimer obtained by depolymerization (%) = (Number of moles of dimer obtained) / (Number of moles of terephthalate units in the input polymer structure) × 100

[0132] Yield (%) of by-product (MHET) obtained by depolymerization = (Number of moles of MHET obtained) / (Number of moles of terephthalate units in the input polymer structure) ×100

[0133] 1.1 Comparison of reaction characteristics of depolymerization using metal salts as catalysts [Table 1]

[0134] Table 1 shows the most commonly used counters used to compare and explain the effects of the examples in the present invention. Under specific conditions, the performance of the glycolysis reaction of polymer raw materials containing ester functional groups was evaluated. This is because of the excess ethylene glycol (per mole of polymer repeating unit). Using 12 moles, under atmospheric pressure, ethylene glycol reflux conditions (197°C) are used. A coriscision reaction was carried out. Zinc acetate, the most commonly used catalyst for the reaction, was added to the polyethylene. To investigate the depolymerization performance of ethylene terephthalate, experimental example 1 was performed according to the method described above. A polymerization reaction was carried out and is shown as Comparative Example 1. Furthermore, a modified combination was performed according to an example of the present invention. As a compatible catalyst, an alkali acetate salt in the same molar quantity as zinc acetate was selected, and the comparative example was... The depolymerization reactions carried out using the same number of moles of catalyst as added in step 1 are shown as Comparative Examples 2 and 3. Ta.

[0135] As already reported in numerous patent and non-patent prior art documents, zinc acetate as a catalyst When applied (Comparative Example 1), the polymer was completely decomposed in only 2 hours of reaction, and the BHET was 90 It was obtained in a high yield reaching %. In contrast, the reaction was carried out under the same conditions, but with potassium as the catalyst. This was carried out using acetates that have alkali metals such as um or sodium as cations. High reactivity was also observed in the depolymerization of polyethylene terephthalate, The monomer BHET was observed to have low selectivity. Yield can affect productivity and is used to separate low-value, inexpensive by-products. This process can potentially cause various economic and environmental problems, such as the burden of the refining process and the disposal of by-products. ru.

[0136] 1.2 PET glycolysis under low-temperature conditions To depolymerize polymers containing ester functional groups, a glycolysis reaction pathway is selected. In this case, as previously shown in the depolymerization reaction conditions of Comparative Examples 1-3, the exchange esterification reaction The boiling point of ethylene glycol added as an addition product (197°C) or a higher temperature. The reaction is generally carried out using [a specific method]. Even if an excess of catalyst is used, or if it is used at a very dilute concentration, Even when polymer raw materials are applied to the reaction, lowering the reaction temperature will not provide the necessary sufficient temperature for the depolymerization reaction. Because it lacks activation energy, its reactivity is very low, or it is a relative side reaction. The reaction rate increases, making it impossible to obtain the desired product. On the other hand, a high reaction temperature is required. In the case of a manufacturing process, the method of applying fuel or utility to supply the heat source for the reaction. This can be restricted, and excessive costs may be required for investment in equipment and for the operation of processes. This is also possible. Therefore, low-temperature glycerides can provide high reactivity and high yield. Designing the colisic depolymerization reaction is an effective and decisive step in ensuring the economic viability of the process. It can provide steps.

[0137] Depolymerization of polymers containing ester functional groups was carried out along the glycolysis reaction pathway. Numerous prior studies have indicated that this corresponds to the boiling point of ethylene glycol (197°C) or higher. The reaction conditions are presented, and it is not simply a catalyst or a catalyst composed of only one or specific components. Even if a composite material is added by mixing and adding it, it is very difficult to lower the reaction activation energy. It is known to be difficult. In particular, significantly lowering the reaction temperature while maintaining equivalent performance is challenging. No substantial examples of reaction systems capable of achieving this have been reported.

[0138] In this invention, as a means to overcome this, the bonding vessel between the aromatic ring and the alkyl group The catalytic reaction is activated by adding a compound having at least one oxygen group in its active group as an additive. This significantly reduces the energy, resulting in a temperature 40°C lower than in typical glycolysis reactions. A new method for depolymerizing polymers containing ester functional groups in a low-temperature region is being developed. This attempts to present a reaction pathway. This is necessary to maintain performance because decomposition can occur at high temperatures. Alternatively, possible organic compounds that are difficult to recover, or Group 1A or 2A compounds that have low toxicity to the human body. Regarding low-temperature glycolysis reactions in which metal salts consisting of cations of metal groups can be used as catalysts... I will try to propose a way to achieve that.

[0139] To specifically explain the effect of the present invention on low-temperature glycolysis reactions, a comparative example and Although composed of the same elements, the glycolysis reaction results when carried out under low temperature (153°C) conditions. The results are shown in Table 2. In order to explain the characteristics of the low-temperature glycolysis reaction according to the present invention, all The conditions are configured identically, but the reaction results for each catalyst system are determined based on the presence or absence of additives. The results are shown separately as comparative examples and examples.

[0140] In Comparative Examples 4-6, polymer raw materials, reaction catalysts, and ethylene glycol were added, and the reaction temperature was... Except for maintaining the temperature at 153°C, glycolysis depolymerization was carried out in the same manner as in the comparative example. The results were evaluated. In Comparative Example 4, a depolymerization reaction was carried out using zinc acetate as a catalyst. In Comparative Examples 5 and 6, potassium acetate and sodium acetate were used as catalysts in the depolymerization reaction. The response was carried out. Example 1 uses a zinc acetate catalyst, which corresponds to the chemical formula 1 above. The compound anisole was added as an additive, and the depolymerization reaction was carried out according to the method in Experimental Example 2. Examples 2 and 3 used potassium acetate or sodium acetate as catalysts, respectively. The experiment was conducted using the same method as in Example 1, with the exception of the method used in Example 1.

[0141] The anisole used as the aforementioned additive can be extracted from natural sources, but it is also industrially produced. It can also be synthesized in large quantities and is used as a raw material or precursor for the manufacture of fragrances and perfumes. Furthermore, it is significantly less harmful compared to other aromatic compounds.

[0142] The raw materials derived from PET bottles used in the comparative examples and examples have an amorphous structure. Since raw materials with a large unit area of ​​0.3 mm or less in thickness are introduced into the reaction, the initial depolymerization From the initial stage, a high effective contact area can be maintained with additives, catalysts, and reactants. Depolymerization raw materials with different geometric shapes, such as the degree of polymerization of molecules, properties, and thickness of the material, are used for mass transfer and This can affect the reaction rate and ultimately the target product of depolymerization. This can have a significant impact on the yield and performance. Examples 4-6 show waste plastics that can be discharged in daily life. Among plastics, multi-layered PET bottles, colored PET label material, polyester The tel fibers are crushed and 1 cm 2 The waste resin prepared in the following area was quantified as a polymer raw material. Subsequently, depolymerization reactions were carried out for each of them. The reaction conditions were the same as in Example 3, which uses raw material 1. Depolymerization was performed.

[0143] [Table 2]

[0144] As shown in Table 1, Comparative Example 1 involved applying zinc acetate as a catalyst and applying a high temperature of 197°C. So, most of the PET was decomposed, but with the same reaction mixture composition at a low temperature (153 According to the results shown as Comparative Example 4 in Table 2, where depolymerization was performed at (°C), the conversion rate was less than 10%. It showed extremely low reactivity. In addition, the proportion of by-products was relatively high compared to the target product. Obtained.

[0145] Comparative Examples 5 and 6 contain alkali metal cations instead of zinc acetate in a similar manner. The reaction is carried out using metal salts, more specifically potassium acetate and sodium acetate, as catalysts. In comparison with Comparative Example 4, the conversion rate increased slightly, but the reactivity was greatly improved. It was found that this was not possible. At the same time, the amount of by-products produced increased significantly. Comparative Examples 1 and 4 showed higher BHET selectivity.

[0146] The reaction results of Example 1 were obtained by adding only anisole to the reactant composition of Comparative Example 4, resulting in zinc acetate. Low-temperature (153°C) glycolysis was performed using [the specified method]. Comparative Example 4 and Example 1 Comparing the depolymerization results, the addition of the additive according to the present invention dramatically alters the depolymerization performance. It can be seen that it produces such effects. The reaction in Example 1 occurred at temperatures above 40°C and at low temperatures. Despite being a reaction, a BHET yield of 82.5% was obtained within 2 hours. When the time was extended to more than 3 hours, a BHET yield of 85% to 90% was obtained. .

[0147] A more dramatic effect was observed when the catalyst was changed to an alkaline metal acetate catalyst. Example For example, potassium acetate and sodium acetate are used as catalysts, and the reaction is performed at low temperature (15°C) in the presence of additives. The results of the glycolysis reaction carried out at 3°C ​​(Examples 2 and 3) are compared to the results of the high-temperature reaction (comparison). Examples 2 and Comparative Example 3) and the case of a low-temperature glycolysis reaction without additives (Comparative Example 5 and It can be compared with Comparative Example 6). The reactant composition of Comparative Example 5 (or Comparative Example 6) is aniso In Example 2 (or Example 3), where low-temperature glycolysis was performed by adding a rubbing agent, the presence of the additive Similar to Example 1, in which depolymerization was carried out using zinc acetate as a catalyst, high depolymerization reactivity was observed. The following was observed. Depolymerization was performed by adding anisole to a reaction system using an alkali metal as a catalyst. When this was done, even though the reaction temperature was kept low at 153°C, all of the raw PET material was processed within 2 hours. In addition to being observed to be highly reactive, being completely decomposed internally, the selectivity of BHET was also significantly improved. It can be seen that it is improved. It is effective in glycolysis reactions at high temperatures of 197°C, and Catalysts in modified forms, such as catalysts in the form of other salts containing alkali metals, or guanidine-based catalysts. Even for catalyst systems containing catalysts in the form of nonmetallic organic materials, anisole can be added. As a result, the reactivity was dramatically increased in low-temperature glycolysis reactions below 153°C. Improved selectivity was observed for the catalyst system. Low-temperature depolymerization depending on the type of catalyst. The performance will be explained in more detail in Section 1.7.

[0148] On the other hand, the decomposition of polymer raw materials with different properties under the same conditions in Examples 4 to 6 Comparing the reaction results, intrinsic viscosity (IV~) Because the ratio (0.65) is low, it is expected that there will be little constraint on mass transfer during the depolymerization process. In Example 6, which uses polyester fibers as a raw material, PET flakes are used as a raw material (IV= It was found that a higher yield of BHET can be obtained compared to other cases where it is used (0.74). In Example 4, which used multilayered PET flakes as raw material, the process took 2 hours. The BHET yield was observed to be somewhat low at 82.5% when only the reaction was performed.

[0149] On the other hand, thin colored PET films, which are not expected to be significantly affected by mass transfer, are used as the primary material. In the case of Example 5, which was used as a material, high initial reactivity was observed, but the yield was 8 It was observed to be as low as 0% or less. In this case, the yield did not improve even when left in the reaction conditions for a long time. The low BHET yield, which has not been improved, is due to impurities such as pigments having a negative impact on the depolymerization performance. It can be presumed that this is a result of the influence exerted.

[0150] 1.3 Temperature range for low-temperature depolymerization reactions In the following specific example, the composition of the reactants effective for low-temperature glycolysis is maintained, thereby, This is intended to explain the range in which reaction or depolymerization performance is effective at low temperatures. In the following example, in order to determine the qualitative and quantitative reaction characteristics of the depolymerization reaction, reactions other than temperature are used. The experiment will be conducted under identical conditions, while varying the temperature to observe the depolymerization performance. Includes specific examples.

[0151] [Table 3]

[0152] Table 3 shows the results obtained using the same method as in Example 3, except that the reaction temperature was maintained at 130-150°C. This is the result of performing and evaluating glycolysis depolymerization. Per mole of polymer repeating units Sodium acetate (NaOAc) is used as a catalyst at a rate of 0.04 moles, and anisole and ethinopropyl alcohol are used. Lenglycol was used at 4 moles and 12 moles, respectively. The reaction time was 3 hours or 6 hours in total. The experiment was repeated to ensure that the reaction occurred. The reactants produced were each prepared in the same manner. After preparing the samples and performing quantitative analysis by HPLC, the conversion rate and yield for each were compared. did.

[0153] Anisole is added to the PET raw material according to an example of the reactant composition according to the present invention. Low-temperature glycolysis revealed that clear and effective reaction characteristics were exhibited at temperatures above 130°C. At temperatures above 145°C, the conversion rate approaches 100% when exposed to the reaction for a long period (6 hours). A very dramatic effect was observed.

[0154] On the other hand, in Example 11, where depolymerization was carried out at 150°C, complete depolymerization occurred within 3 hours due to high reactivity. Although it was decomposed, prolonged exposure to reaction conditions resulted in the monomer product (BHET) The selectivity was observed to be somewhat low. This is because the target product that has already been generated is at high temperatures. When exposed to continuously, the side reaction pathway of BHET hydrolysis occurs. This is because the MHET yield gradually increases due to the following: Therefore, the mass of polymer is complete. To ensure complete decomposition and prevent the side reaction rate from progressing, not only temperature but also reaction It is preferable to optimize the response time to improve the final yield of the target product.

[0155] 1.4 Performance evaluation of depolymerization reaction based on the amount of additives The following specific example maintains the composition of reactants and reaction conditions that are effective for low-temperature glycolysis reactions. Both are intended to explain the effective range in which the additive's effects are manifested. In the example, in order to determine the characteristics of the depolymerization reaction, the reaction conditions are kept the same, but the addition of an additive... This includes specific examples of procedures performed to observe depolymerization performance by varying the amount added.

[0156] Table 4 shows the results of PET depolymerization without the addition of additives (Comparative Example 5 and Comparative Example 6), The reaction was carried out by varying the amount of additive added to the reaction (Examples 12 and 13) Distribution of the product obtained after 2 hours of depolymerization at a low temperature (153°C) using the following composition This result shows a change. Specifically, the amount of anisole, an additive, added was changed from 0g to 39.4g. The experiment was repeated by varying the value up to g (7 moles per repeating polymer unit mole). Yes, glycolysis decomposition was performed in the same manner as in Example 2 or Example 3, except for the amount of additives. This falls under the category of having implemented and evaluated the process.

[0157] [Table 4]

[0158] Although a metal salt containing an alkali metal cation is used as a catalyst, the chemical formula according to the present invention In Comparative Examples 5 and 6, where no additive corresponding to 1 was added, the glycolysis reaction was very weak. Although the response performance was observed, Example 12 and the implementation were carried out with the addition of even a small amount of the additive (anisole). Looking at the results of Example 13, not only did the reactivity increase, but the glycolysis reaction of PET also increased. It can be seen that the selectivity of the BHET produced is also greatly improved. In particular, the polymer raw material to which it was applied When the amount of additive added increases to a ratio of 3 molars or more compared to the raw material, polymers can be produced even in a reaction time of only 2 hours. It can be seen that the product is largely decomposed, and a high level of selectivity for the target product is maintained.

[0159] On the other hand, the additives used are used as reactants when the temperature drops below 100°C. Phase separation occurs from the excess ethylene glycol, and also for the purification of the target product, excess Even when water is added, only a very limited concentration of the additive remains in the aqueous solution containing the target product. Therefore, it can be easily recovered. Thus, by liquid-liquid extraction, the additive can be recovered. Although it can be easily separated, at the end of the reaction, the reaction temperature should be set to the boiling point of the additive. After raising the pressure, the condenser separates some or all of the condensed additives into the external flow. Liquid separation methods are more advantageous in terms of efficiency. The additives according to the present invention do not directly participate in the reaction. Although it is a compound, it has been shown to have the effect of lowering the activation energy of the reaction, and is therefore classified as a catalyst. Although they have similar properties, in the absence of metal salts or other catalysts, the direct reactivity is... Because it does not produce a boost, it exhibits properties similar to a co-catalyst.

[0160] 1.5 Performance evaluation of depolymerization reactions using catalytic amounts The following specific example maintains the reactant composition and reaction conditions that are effective for low-temperature glycolysis reactions. This also serves to explain the effects of adjusting the amount of catalyst added. In the following example, To determine the characteristics of the polymerization reaction, the reaction conditions were kept the same (reaction temperature: 153°C, reaction time) The reaction time was 2 hours (additive: anisole), but the amount of catalyst added was varied to observe the depolymerization performance. This includes specific examples of what will be done to achieve this.

[0161] [Table 5]

[0162] Table 5 shows the amount of catalyst (metal salt containing alkali metal cation) added, ranging from 0g to 1.0g (high Other than repeatedly performing experiments while changing the molecular repeating unit to 0.20 moles per mole, The glycolysis depolymerization was carried out by the same method as in Example 2 and Example 3, respectively. These were evaluated and are shown separately as Example 14 and Example 15.

[0163] The catalyst is added in trace amounts, less than 0.01 moles relative to the repeating units of the polymer raw material. A significant decrease in reactivity was observed, but the selectivity of the target product, BHET, was It was observed to be higher. This is because, as the amount of catalyst added increases, the side reaction rate increases. It can be expected that this will have a greater impact. The catalyst is repeated in the polymer raw material When added in a ratio exceeding 0.01 moles per unit, the high reactivity causes the added substance to react with the added substance. Most of the PET that was added was decomposed, and when added in an excess of 0.03, complete decomposition occurred. For complete decomposition to occur, the amount of catalyst should be greater than 0.03 but less than 0.10 moles. Within the range of concentrations, the selectivity and yield for the target product (BHET) vary slightly depending on the amount of catalyst. Although some changes were observed, when the catalyst was used in excess of 0.10 moles or more, the amount of byproduct produced increased. This increased. From this, we were able to confirm that the BHET yield was slightly lower. Observations of the characteristics of the depolymerization reaction depending on the amount of catalyst added revealed that, over a relatively wide range, the amount of catalyst added was... This allows for the maintenance and adjustment of reaction performance, and after the reaction is complete, some of the catalyst can be reused. Even if the catalyst concentration is not precisely adjusted during the process, one of the catalysts that is perceived to have disappeared may still be present. Since only the parts need to be replenished, it is expected that flexibility can be ensured in the operation of the process. It is possible.

[0164] 1.6 Performance evaluation of depolymerization reactions based on the type of additive The following specific example maintains the reactant composition and reaction conditions that are effective for low-temperature glycolysis reactions. This also explains the effects of the reaction when some or all of the additives according to the present invention are modified. This is for the purpose of determining the characteristics of the depolymerization reaction. The reaction conditions are kept the same (reaction temperature). At 153°C, the reaction time was 2 hours, and the catalyst was KOAc. However, between the aromatic ring and the alkyl group... When using compounds that contain oxygen within their functional groups, should the number of functional group bonds be changed? , or a specific example of observing depolymerization performance by adding a modified form of additive. include.

[0165] [Table 6]

[0166] Table 6 shows alternative forms of additives used instead of anisole, which was used as an additive in the examples. This study aims to investigate the effect of using this method on low-temperature depolymerization reactions. Other forms of additives can be used instead of anisole, at a rate of 4 moles per mole of polymer repeating units. Except for the addition of the substance, glycolysis depolymerization was carried out and evaluated in the same manner as in Example 2. Ta.

[0167] Comparative Example 5, in which PET glycolysis was performed without the addition of additives, and the aromatic ring and alkyl group The procedure was carried out by adding a compound containing at least one oxygen atom in the bonding functional group between the two. Comparing the results of Example 2 with those of Examples 16-20, there are some differences in performance, however It can be confirmed that the additive effect of the invention is clearly observable. According to the results of the depolymerization performance in Examples 16 to 18, which show examples of agents, the chemical formula 1 When the value of m increases to 2 or more, a slight decrease in reactivity and selectivity for the target product is observed. Examples 19 and 20 involved alkyl groups bonded by oxygen with a carbon number of 1. Modification additives to which other forms of functional groups, either absent or not alkyl functional groups, may be further bonded. This is an example of depolymerization carried out by adding [a certain compound]. Based on the results of depolymerization in Examples 18 and 19 Although some deviations were observed in reactivity and BHET yield, the effects of the present invention It was found to be clearly observable. Comparative Example 7 has a structure similar to the additive according to the present invention. However, the central functional group of the compound is a different form of methoxycyclohexane (at least one Alkyl groups are linked via linkers, and the linkers have at least one oxygen atom. (However, the central functional group is not an aromatic ring but a saturated cycloalkane compound with the same number of carbon atoms.) The depolymerization performance was evaluated by replacing the additive. The comparative example without the additive was also evaluated. Even lower reactivity and BHET selectivity were observed compared to case 5.

[0168] In specific embodiments of the present invention, the additives to be added are evaluated based on the same number of moles. However, if the morphology of the bonded functional groups differs, the interaction with the raw materials and additives may manifest differently. Therefore, the form and amount of additives added to the reactants are adjusted to compensate for any imperfections in performance. It is also possible to do so.

[0169] 1.7 Performance evaluation of low-temperature depolymerization reactions using diverse catalysts The following specific example maintains the composition of reactants and reaction conditions effective for low-temperature glycolysis reactions. The reaction is carried out at a temperature of 153°C for 2 hours, and some or all of the catalyst types according to the present invention are used. This is to explain the effect of the reaction when parts are changed and used. The characteristics of the depolymerization reaction are explained. To distinguish between alkali metals or alkaline earth metal catiota, the reaction conditions are kept the same while determining the reaction type. A metal salt containing ammonium compounds is used as a catalyst, and counterions are carbonic acid, bicarbonate, and alcohol. Either transform it into another form such as a side, or apply an organic compound catalyst that does not contain metal. This includes specific examples of observing changes in depolymerization performance.

[0170] [Table 7]

[0171] Table 7 compares and evaluates the low-temperature (153°C) depolymerization performance of various catalyst forms described. It is worthwhile. Adding the additive according to the present invention, all of the additives added to the polymer The reaction rate limiting region (kinet) is created by restricting the amount of compound so that the differences in performance between catalysts become more pronounced. The evaluation was performed using the IC Limited Regime. The catalyst is a polymer repeating unit. Only 0.02 moles were added per mole, and approximately 32.30 g of ethylene glycol (high molecular weight) was added. Approximately 16.88g of anisole (10 moles per mole of repeating units) (high molecular weight repeating units) Glycolysis depolymerization is carried out in the same manner as in Example 1, except that 3 moles (per mole) were used. The following was implemented and evaluated. Although not included in the results, the counterion morphologies listed in Table 7 were different. Although one of the various modified catalysts or organic compounds was used as a catalyst, the additive according to the present invention The depolymerization was carried out at a low temperature (153°C) without adding any additives, and the performance of the catalyst alone was observed first. As can be predicted from the detailed comparison explained earlier, even if the catalyst is changed, additives are added. If the reaction was carried out without doing so, the performance results were similar to those of Comparative Examples 4 to 6, showing low reactivity and extreme temperatures. A restrictive BHET yield was observed for the first time.

[0172] Example 21 using a metal salt catalyst in which the cation is a Group 1A metal and the anion is a carbonate ion. And in the case of Example 22, as in the case where a catalyst consisting of an acetate ion as the anion is applied, high High reactivity and high monomer yield were observed. In contrast, when the same number of moles of bicarbonate were used in anio In the cases of Examples 23 and 24, which were given as [a specific compound], relatively low reaction performance was observed. Glycolysis was performed under the same conditions, but with the metal carbonate catalyst consisting of a group 2A metal cation replaced. In the case of the reaction (Example 25), the alkali metal salt catalyst having bicarbonate as an anion was used. High reactivity and high monomer yield were observed. On the other hand, when the same conditions were applied and the metal was included... Triazabicyclodecene, an organic compound catalyst that does not possess the necessary properties, is applied as the same molar quantity of catalyst. In this case (Example 27), the conversion rate of the reaction was 99.0% or higher, and the yield of BHET was 81%. A highly effective glycolysis reaction was observed, with a yield of over 0.8%.

[0173] As can be seen from the results of depolymerization reactions using various modified forms of exchange esterification catalysts, When the additive according to the invention (a compound represented by chemical formula 1) is added, the temperature at low temperatures (153°C) is reduced. The glycolysis reactivity to polymers containing tel functional groups can be significantly improved. It can be seen that BHET can be obtained in high yield below the boiling point of ethylene glycol.

[0174] 1.8 Purification and Analysis of Glycol Addition Monomers Produced After Depolymerization Reaction In the following specific example, a polymer containing an ester functional group is subjected to a depolymerization reaction using the method of the present invention. After that, the physical and chemical properties, including purity, of the BHET product obtained from the purification process were assessed. This is for gripping. Such a process may include a separation method for recovering the additive. It is possible. As explained in the specific example above, when additives are added, the low temperature range below 153°C is possible. It is possible to perform high-performance glycolysis reactions in the region and can be used in high-temperature ranges above 197°C. It becomes possible to introduce catalyst systems that are otherwise difficult to implement, which brings about various advantages in the purification process. For example, the range of catalytic reactions that exhibit optimal performance in the low-temperature range is for alkali metal salts. It can be expanded, and organic compounds that may decompose at high temperatures can be applied as catalysts without being lost. Therefore, purification and recovery of the substance are easy. Also, it is mainly used in existing commercial processes. Therefore, it is not necessary to use catalysts containing harmful metals such as zinc, lead, and other heavy metals. Manufacturing raw materials for environmentally friendly, high-quality materials, or creating a perfect circular economy for waste plastics. It can be expected to have value as a recycling technology.

[0175] In the following example, the mass ratio of the compound presented in this invention is kept the same, and high temperature Depolymerization reaction using zinc acetate as a catalyst without additives at (197℃), and Aniso The solution was prepared by adding a phosphate group and using group 1A metal acetate as a catalyst at a low temperature (153°C). Glyco obtained from each of the reaction products obtained from polymerization reactions after the product purification process. This includes specific examples of procedures performed to evaluate the yield and purity of the added monomer.

[0176] Table 8 shows the quality of the polymer raw materials, reaction catalyst, and ethylene glycol used in the depolymerization reaction. The ratio is 1:0.1:4 (if additives are added, the additive should be twice the mass of the polymer raw material). A certain amount is added (using) and depolymerization is carried out according to the method of Experimental Example 1 or Experimental Example 2. In Comparative Example 8, which used a zinc acetate catalyst without additives, at high temperature (197°C), Example 28, in which anisole was added and potassium acetate and sodium acetate were used as catalysts, In the case of 29, depolymerization was carried out at a low temperature (153°C), and the purification process was the same as in Experimental Example 3. The depolymerization product was obtained through the following process. The purified final product was then treated with ICP and 1 H-NMR The properties were observed. For Comparative Example 8, the product was cleaned through the process of Experimental Example 4, and the product ( Comparative Example 9) We confirmed whether the quality had improved.

[0177] [Table 8]

[0178] The residual metal amounts in Comparative Example 8 and Examples 28-29 shown in Table 8 represent the glycolysis reaction of PET. After obtaining the product according to the pathway, the BHET obtained by primary recrystallization here... The residual metal content is detected by ICP-MS and ICP-AES with a detection limit of 1 ppm or higher. This is the result of analysis performed using the analytical method.

[0179] In the case of BHET that has undergone a purification process after being reacted with zinc acetate, some residual metals can be detected. The zinc used as a catalyst is classified as an important inorganic substance for the human body, If the human body is exposed to large doses or sustained exposure through the use of products such as beverage containers, It is classified as a toxic metal that can cause toxic diseases. It remains in plastics. Zinc is naturally excreted as waste, accumulates in plants and animals, and is then indirectly absorbed back into the human body. Various side effects may occur depending on the route of administration. Therefore, alternatives may be necessary. Possible non-toxic metal catalyst-based low-temperature depolymerization reaction technologies offer not only commercial viability for products but also environmental benefits. It could be advantageous from the perspective of reducing pollution.

[0180] Therefore, an alkali metal salt is used as a catalyst, but the same as zinc acetic acid used in Comparative Example 8. The same mass is introduced as a catalyst (a larger amount of metal moles is used than in Comparative Example 8). The reaction and purification were carried out using the following method. Referring to the results of Example 28 (or Example 29), A No residual metal was detected in the final product manufactured using the potassium metal salt catalyst. The metal ions that make up the substance are themselves essential electrolytes in the human body, and are less harmful than zinc. It has the advantage of being low. Metal residue in the products manufactured by Examples 28 and 29 The reason for the low distillate volume is that during the purification process, the components that make up the catalyst are far more abundant in aqueous solution compared to zinc acetate. Because it has a very high degree of ionization, dissociation occurs easily, and recrystallization and physical filtration are excessive. Within a certain timeframe, it either remains in the BHET product recovered as a solid phase or does not leach into the aqueous phase. This is because the amount of metal is extremely dilute.

[0181] Qualitative properties of purified glycol-added monomers 1 Observed by 1H-NMR. The specific spectra are shown in Figures 1 to 3.

[0182] For high-temperature glycolysis-based monomers obtained by purification using the method of Comparative Example 8 1 H-NM R is as follows:

[0183] 1 H-NMR (500MHz, DMSO-d6)δ(ppm):8.12(s, 4H) , 4.99(br s, 2H), 4.33(t, 4H), 3.73(t, 4H)

[0184] Ethylene glycol against the monomer of BHET obtained from the glycolysis of PET Referring to numerous prior studies on NMR spectra, around 4.95 ppm, the terminal The characteristic peak originating from the hydrogen of the hydroxyl group, which is an end group, is due to the hydrogen of the adjacent ethylene group. It is divided into a triplet, and around 3.73 ppm, the hydroxyl group A quadruple line characterized by hydrogen atoms bonded to adjacent carbon atoms (c in Figures 2 and 3). (Quartet) morphology peaks are observed and are commonly reported in the literature. However, the BHET monomer obtained after simple purification according to the method of Comparative Example 8 1 H-NM The R spectrum shows a broad single peak around 4.99 ppm, and 3.27 ppm. A triple line was observed near m. This indicates impurities remaining in BHET, as shown in Table 8. Therefore, it can be presumed that this was caused by interference from the zinc acetate catalyst.

[0185] Comparative Example 9 is the amount of metal residue in the glycol-added monomer obtained in Comparative Example 8. To reduce the amount, an additional purification method was performed. When performing the additional purification according to the method in Experimental Example 4: Next, distilled water maintained at a constant temperature was added to the white powder product finally obtained from Comparative Example 8. The mixture was then stirred for about 1 hour. After completion, the mixture was filtered using the same filter as that used in Comparative Example 8. The precipitate that was washed was collected and dried. Further purification was carried out using the method shown in Experimental Example 4. The process is repeated, but the BHET monomers that no longer detect metal within the ICP detection limit are After obtaining the results, remeasurement was performed. 1H The characteristic peaks of the NMR spectrum are as follows:

[0186] 1 H-NMR (500MHz, DMSO-d6)δ(ppm):8.12(s, 4H) , 4.97(t, 2H), 4.33(t, 4H), 3.73(q, 4H)

[0187] 4.9 was observed with the high-temperature glycolysis-based monomer obtained by purification using the method of Comparative Example 8. A broad single peak was observed around 9 ppm, which then separated into a triple line around 4.97 ppm. Around 3.73 ppm, a quadruple line was observed, rather than a triple line peak.

[0188] The following describes glycolysis performed using the method of Example 28 (using potassium acetate), and the product is purified. The analytical method of Comparative Example 8 was applied to the BHET monomer recovered after preparation without any additional purification process. Similar to the law 1 Structural analysis was performed using 1H-NMR, and the observed characteristic peaks are as follows: there were.

[0189] 1 H-NMR (500MHz, DMSO-d6)δ(ppm):8.12(s, 4H) , 4.95(t, 2H), 4.33(t, 4H), 3.73(q, 4H) The BHET (actual product) was reacted and purified using the method of Example 29 (using sodium acetate) and recovered. The same process and method as in Example 28 are applied. 1 H-NMR spectrum I was able to obtain it.

[0190] These comparative examples and examples show the difference between monomers with residual zinc metal and high-purity monomers. Just as structural properties are distinguished, when using the catalyst system prepared according to the present invention, The BHET obtained can be obtained in high purity even through a simple purification process. Therefore, efficient purification This is possible and is advantageous in terms of productivity and economics.

[0191] 2. Extractant for removing color-producing impurities from polymer monomers containing ester functional groups. , and a method for purifying monomers using the same

[0192] [Ingredients 5 and 6] Colored label paper made from PET polymer is produced from waste plastic containers that have been discarded after consumption. Only the materials were collected and separated by their main constituent hues, and then cut so that each side was 0.5 cm or smaller. Cut and prepare raw material 5, and cut the polyester fabric that has been dyed using disperse dyes 1 cm 2 Raw material 6, to be used as fiber raw material, was prepared so that it had the following area.

[0193] Experimental Example 5: Liquid-Liquid Extraction Stage After the reaction was complete, approximately 200g of distilled water at 95-100°C was added to the filtrate obtained by filtration. Transfer to a container maintained at 75°C and stir. After 1 hour, stop stirring and then phase separation will occur. When this occurred, the aqueous solution layer shown below was taken and left at room temperature to lower its temperature.

[0194] Experimental Example 6: Liquid-Liquid Back Extraction Step In the same liquid-liquid extraction step as in Experimental Example 5, the organic solution layer was separated by adding approximately 95-100°C distilled water. After adding 200g, transfer to a container maintained at 75°C and stir, then stop stirring after 1 hour. Once phase separation occurred, the lower aqueous solution layer was taken and left at room temperature to lower its temperature.

[0195] Experimental Example 7: Depolymerization and Productization Stage In a storage facility maintained at a temperature of 4°C, the reaction mixture solution containing the monomer, or Experimental Example 5 or After the aqueous phase extracted in Experimental Example 6 was left to stand for 12 hours, the crystallized solid phase was subjected to physical filtration. After removing a large amount of water using the method, the solid portion was taken. This was then heated again to a temperature of 60°C. The product was then transferred to a maintained vacuum dryer and vacuum-dried for more than 12 hours to obtain the depolymerized product.

[0196] Experimental Example 8: Organic solvent and dye recovery step In Experimental Example 5 or Experimental Example 6, the upper phase (organic layer) remaining after the aqueous solution layer has been separated was subjected to simple distillation using a simple distillation apparatus. Anisole was separated into the vapor phase and condensed to obtain the liquid phase. The residual portion containing a large amount was It was possible to obtain a viscous semi-solid phase product. Each of the obtained products was measured to an accuracy of ±0. The amount was quantified using a high-precision balance with an accuracy of 0.1 mg.

[0197] 2.1 Production of high-purity monomers from waste PET film containing pigments Comparative Examples 10 and 11 are colored PET films containing pigments (classified as yellow and green). The raw material 5 is used as the polymer raw material, but the reaction conditions of Comparative Example 1 and Comparative Example 2 described in Table 1 are Depolymerization was carried out using the compound composition, and each of the resulting products was subjected to the filtration method of Experimental Example 3. Therefore, after removing the oligomer from the reactant, the monomer product was obtained by the process in Experimental Example 7. .

[0198] Example 30 uses raw material 5 and the same reactant composition and reaction conditions as Example 2 to decompose. After performing the extraction and liquid-liquid extraction according to the method in Experimental Example 5, the aqueous solution phase was obtained and the method in Experimental Example 7 was used. The monomer product was obtained through the process, and Example 31 is the aqueous solution obtained in Example 30. Add anisole (22.5g) to the liquid layer and repeat the liquid-liquid extraction step of Experiment Example 5 one more time. After the return process, the monomer product was obtained by following the procedure in Experimental Example 7.

[0199] Example 32 involves adding approximately 22.5 g of anisole and 95g of 95 to the depolymerized product obtained from Comparative Example 10. After adding approximately 200g of distilled water at 100°C, perform the liquid-liquid extraction as in Experimental Example 5, and then the aqueous solution The monomer product was obtained by taking the phase and following the method of Experimental Example 7.

[0200] Example 33 uses the organic layer separated in the liquid-liquid extraction process of Example 31 to extract the liquid from Experimental Example 6. - After performing the liquid-back extraction step, the aqueous solution phase is taken and the monomer product is obtained by the method of Experimental Example 7. That was the case.

[0201] Nuclear magnetic resonance spectrometer (model Name: Monomers purified using Bruker Avance II 500MHz Structural properties were confirmed. The depolymerization process was determined from the relative area ratio of the mass value of the measured sample and the characteristic peak. The amount of residual color-producing organic foreign matter in the product was estimated. In the case of purified monomer, 20 mg was used. In the case of machine foreign matter, samples were measured by diluting 10 mg in 0.7 ml of DMSO-d6 solvent. It was used for that purpose.

[0202] Glycolysis is a process that uses polymers containing ester functional groups as raw materials. BHET(bis(2-hydroxyethyl)terephth) obtained from the reaction alate monomer and pigment recovered and concentrated from colored PET film (according to Experimental Example 8) (for manufacturing) 1 The H-NMR spectra are shown in Figure 5. Processes of Examples 31 to 33 The depolymerization product manufactured by this method is a BHET monomer purified to a high purity of over 99.9%. - corresponds to this, and this was diluted and measured. 1 In 1H NMR spectra, numerous previous studies have reported... The observed peak values ​​were very similar to those reported as the characteristic peak reference values.

[0203] 1 H-NMR (500MHz, DMSO-d6)δ(ppm):8.13(s, 4H) , 4.96(t, 2H), 4.32(t, 4H), 3.72(q, 4H)

[0204] As reported, at around 4.96 ppm, it is contained in the hydroxyl group as the terminal group. The characteristic peak caused by the hydrogen is due to the interaction with the hydrogen of the adjacent ethylene group. It was observed as a triplet, and around 3.72 ppm, hydroxy Hydrogen directly bonded to an ethylene functional group adjacent to a syl group (as shown in Figure 5 in the BHET chemical analysis). The quadruple-shaped peaks characterized by equations 3 and 4 are Observed without distortion.

[0205] NMR spectra of dye-containing organic foreign matter extracted from colored PET film (Figure 5) The upper spectrum is very complex and is not typically used when purifying polymer depolymerized products using conventional physical methods. Applying only a filtration method can remove some of the organic matter, but it does not remove the organic mixture that causes the color. It is clear that this is not easy. In particular, the chemical shift value Organic compounds characterized by concentrations of 0.94 and 4.69 ppm were present even in trace amounts. Furthermore, it has color development characteristics similar to the colored PET film used as the starting material, and according to the present invention... By using this extraction method, high-purity purification of polymer depolymerization monomer products (BHET) is possible. It was Noh theater.

[0206] The mass values ​​of the samples (organic foreign matter and purified BHET) used for NMR spectroscopy were specified. The amount of foreign matter is calculated by comparing it with the integral value of the peak, and each is based on the chemical shift value. The estimated foreign matter content is shown in Table 9.

[0207] [Table 9]

[0208] The yield of the depolymerized product is the total number of moles of repeating units in the polymer added as initial raw materials. With this value set to 100, the amount of the product obtained from each step by HPLC is proportional to the amount of the product. The calculation was performed using the ratio (%) of the number of units. The raw material used was waste PET film containing pigments that exhibit color. The depolymerization was used and recovered by Comparative Example 10, Comparative Example 11 and Examples 30 to 33. The amount of monomer product is listed in Table 9 as BHET molar yield (%). The extraction process was performed twice. Although the above process was repeated, it was observed that the amount of foreign matter was very low, As the mass of monomers lost during the purification process increased, the yield of the final product decreased. .

[0209] 2.2 Production of high-purity monomers from dye-containing polyester fibers Unlike pigments that are dispersed in a solvent and then used to color in the form of particles or powder, this product is dissolved in the solvent. The dyes used in this context are primarily pigments used to color textiles, leather, and other materials. In particular, polymer fibers containing ester functional groups, such as polyester and other fibrous materials, are used. To achieve color, dyes in the form of organic compounds containing one or more aromatic rings are commonly used for coloring. It will be done.

[0210] As the aforementioned dye, in order to prevent discoloration from polymer fibers, terephthalate, which is a component of the fiber, is used. Substances that have a very high affinity for functional groups are used as dyes, and are physically and chemically effective. It must have properties that allow it to be uniformly dispersed in the fibers scientifically, but this will solve High interaction with monomers or low-molecular-weight compounds produced by depolymerization, even after polymerization occurs. Therefore, the separation and purification of high-purity products is not easy. Consequently, the monomer product... Alternatively, a solvent that exhibits some miscibility with low molecular weight compounds but has a strong affinity for organic dyes. When a large quantity is supplied and an excess of hydrophilic solvent is added, asymmetrical distribution of the solute (dye) occurs. It can induce the process and recover high-purity products.

[0211] Comparative Example 12 is identical to Comparative Example 1, except that it uses raw material 6 (dark indigo waste polyester fiber). The monomer product was obtained by the same method as in 1, and in Example 34, raw material 6 was used. Otherwise, the monomer product was obtained by the same method as in Example 31.

[0212] Example 35 uses the organic layer separated during the repeated liquid-liquid extraction process of Example 34 as a raw material. After using it and performing the liquid-liquid back extraction step of Experimental Example 6, the aqueous solution phase is taken and the method of Experimental Example 7 is used. This is how the monomer product was obtained.

[0213] Example 36 involved repeating the liquid-liquid extraction process performed in Example 34 a total of four times, followed by the aqueous solution The liquid phase was taken and the monomer product was obtained according to the method in Experimental Example 7.

[0214] Figure 6 shows the BH obtained from the reaction after depolymerization using colored polyester fibers as raw materials. The NMR spectra for ET monomers and the dyes recovered and concentrated by Experimental Example 8 are shown. .

[0215] A portion of the products manufactured according to the methods of Examples 34-36 was obtained as a sample. 1 H-NMR The spectra are similar to those obtained from Examples 30-33, where pigment-containing raw materials were applied. The main peak was clearly observed from the intrinsic chemical shift value that indicates the structural properties of the BHET monomer. However, if extraction and recovery are restricted, or if additional products are recovered by back-extraction, While the overall yield of the depolymerized product can be increased, the purity of the BHET monomer is 99%. It is limited to a level that does not reach % and contains dye-specific color, effectively removing foreign matter. It is found that this does not happen. The monomer product produced by the specific experimental example of the present invention can be observed. Based on our assessment, even if organic dyes remain in trace amounts of less than 1% by mass, the product may contain pigmented foreign matter. It was easily identifiable by visual inspection that it was present.

[0216] As an example, the reaction product obtained by purifying the reaction product obtained from the depolymerization of waste PET raw material containing the pigment mentioned above was obtained. In order to recover BHET of equivalent quality to the monomer products of purity (Examples 31-33), As seen in the purification process of Example 36, it is clear that numerous repeated extraction steps are necessary.

[0217] Table 10 shows the high-purity monopolymerization reaction mixture obtained using colored polyester raw materials. This is a concrete example showing the process of obtaining Mar. The compound represented by chemical formula 1 is added and then extracted and purified. Applying the process (Experimental Example 5) allows for efficient removal of organic disperse dyes that constitute the color. It was found that when the extraction and purification process was repeated two or more times (Example 34), and when the extraction and purification process was repeated twice The product obtained when back-extraction was performed using the organic phase generated during the extraction process (Example 35) was: Although it had a purity of over 99.5%, trace amounts of dye residue resulted in a pale red powder in the product. The result was obtained as follows. When the extraction and purification process is repeated four or more times, the yield of the final product is approximately 51%. Although the level was very low, the residual amount of dye was detected at a level of less than 0.1%. I was able to obtain the white BHET product.

[0218] [Table 10]

[0219] Having described in detail the specific parts of the present invention, it is clear that the conventional methods in the art are... For those with knowledge, such specific technologies are merely preferred embodiments, and It will be clear that the scope of this invention is not limited by this. The substantial scope of the claim is defined by the attached claims and their equivalents. It should. [Industrial applicability]

[0220] A method for depolymerizing a polymer containing an ester functional group, with or without a pigment or dye. A composition for depolymerization and a purification method for selectively separating foreign substances from the monomers of the polymer. This relates to methods, including the manufacture, recovery, and reuse of polymers containing ester functional groups. It has potential for industrial use because it can be useful in the field of technology.

Claims

1. An extractant for removing color-producing impurities from monomers of polyester polymers containing ester bonds in the main chain, The polyester polymer is one or more selected from the group consisting of polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and vectran. The aforementioned color-producing foreign substance is a pigment or a disperse dye in the form of an organic compound containing one or more aromatic rings. The extractant is characterized by being one or more selected from the group consisting of methoxybenzene, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 1,3,5-trimethoxybenzene, 1,2,3,4-tetramethoxybenzene, 1,2,3,5-tetramethoxybenzene, 1,2,4,5-tetramethoxybenzene, 2-methoxyphenol, 1,3-dimethoxy-2-hydroxybenzene, and ethoxybenzene, and is an extractant for removing color-producing foreign substances from monomers of polyester polymers.

2. An extractant for removing color-producing foreign substances from a polyester polymer monomer according to claim 1, characterized in that the monomer of the polyester polymer is obtained from a depolymerization reaction of a polymer resin containing an ester functional group.

3. A purification method for producing high-purity monomers by removing color-producing impurities from monomers of polyester polymers containing ester bonds in the main chain, The polyester polymer is one or more selected from the group consisting of polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and vectran. The aforementioned color-producing foreign substance is a pigment or a disperse dye in the form of an organic compound containing one or more aromatic rings. 1) A step of adding and mixing one or more extractant compounds selected from the group consisting of methoxybenzene, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 1,3,5-trimethoxybenzene, 1,2,3,4-tetramethoxybenzene, 1,2,3,5-tetramethoxybenzene, 1,2,4,5-tetramethoxybenzene, 2-methoxyphenol, 1,3-dimethoxy-2-hydroxybenzene, and ethoxybenzene to a polymer monomer containing an ester functional group that contains a color-producing foreign substance; 2) A step of allowing the mixture from step 1) to stand to induce liquid-liquid phase separation, 3) A purification method for removing color-producing impurities from a polyester polymer monomer to produce a high-purity monomer, comprising the step of separating and discharging the phase-separated liquid-liquid layers into an upper organic solution layer and a lower aqueous solution layer.

4. A purification method for removing color-producing foreign matter from a polymer monomer containing an ester functional group to produce a high-purity monomer, characterized in that, in step 1) above, in addition to the compound represented by chemical formula 1, a hydrophilic liquid or water that cannot be mixed with the extractant compound is added to the monomer containing the color-producing foreign matter.

5. A purification method for producing a high-purity monomer by removing color-producing impurities from a monomer of a polyester polymer according to claim 3, characterized in that the monomer is a mixture obtained after a depolymerization reaction by depolymerizing a polyester polymer, or a mixture obtained after a depolymerization reaction that has been partially purified.

6. A purification method for removing color-producing foreign substances from a polyester polymer monomer and producing a high-purity monomer, characterized by repeating the step of further adding the extractant compound to the separated aqueous solution layer to further extract color-producing foreign substances one or more times, as described in claim 3.

7. A purification method for producing high-purity monomers by removing color-producing impurities from monomers of a polyester polymer according to claim 3, further comprising the step of adding a hydrophilic liquid or water that cannot be mixed with the extractant compound to the separated organic solution layer and mixing, and then performing phase separation again.

8. A purification method for producing high-purity monomers by removing color-producing impurities from polyester polymer monomers according to claim 3, further comprising the step of recovering polyester polymer monomers from the separated aqueous solution phase via recrystallization.

9. (a) Adding one or more extractant compounds selected from the group consisting of methoxybenzene, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 1,3,5-trimethoxybenzene, 1,2,3,4-tetramethoxybenzene, 1,2,3,5-tetramethoxybenzene, 1,2,4,5-tetramethoxybenzene, 2-methoxyphenol, 1,3-dimethoxy-2-hydroxybenzene, and ethoxybenzene to a colored polyester polymer containing ester bonds in its main chain; (b) The step of depolymerizing the polyester polymer, (c) A step of adding a hydrophilic solution or water that cannot be mixed with the extractant compound to the depolymerization reaction product obtained from the depolymerization reaction and mixing it, (d) A step of allowing the mixture from step (c) to stand to induce liquid-liquid phase separation, (e) The step of separating and discharging the phase-separated liquid-liquid layers into an upper organic solution layer and a lower aqueous solution layer, The polyester polymer is one or more selected from the group consisting of polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and vectran. A purification method for producing high-purity monomers by removing color-producing impurities from monomers obtained by the depolymerization of a colored polyester polymer, wherein the colored polyester polymer contains color-producing impurities that are pigments or disperse dyes in the form of organic compounds containing one or more aromatic rings.

10. A purification method for producing high-purity monomers by removing color-producing impurities from monomers obtained by the depolymerization of a colored polyester polymer according to claim 9, characterized in that an organic solvent is recovered from the organic solution layer separated and discharged in step (e) via distillation and recycled therefrom.

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