KR20230097605A - Eco-friendly decolorization and depolymerization of colored polymers containing ester functional groups - Google Patents

Abstract

The present invention relates to a method for decolorizing and depolymerizing a colored polymer containing an ester functional group. The present invention relates to a method for decolorizing and depolymerizing a colored polymer having an ester functional group capable of increasing yield and removing color-expressing foreign substances from the colored polymer.
[Formula 1]

Description

Eco-friendly decolorization and depolymerization of colored polymers containing ester functional groups {Eco-friendly decolorization and depolymerization of colored polymers containing ester functional groups}

The present invention relates to a method for depolymerizing a colored polymer containing an ester functional group while simultaneously removing color-expressing foreign substances.

More specifically, by adding a compound that functions as an extractant for effectively separating and desorbing dye from polyester fibers containing dye and as an additive that improves the conversion rate of exchange esterification reaction, the ester functional group is It relates to a method for decolorizing and depolymerizing a colored polymer comprising

As the industry develops, the increased use of fibers and plastics is causing various environmental and social problems. Recently, in order to solve these problems, physical or chemical recycling technology that applies waste fibers or waste plastic materials discharged after use as raw materials has attracted high attention. Polymer materials containing ester functional groups among waste plastics and waste fibers have thermoplastic properties and can be converted into low-molecular materials through chemical reactions, and can be used in the recycling industry to manufacture recycled materials through physical and chemical recycling processes. , In general, most of the polymer materials discharged after consumption are contaminated with various foreign substances, and contamination of such foreign substances has been pointed out as one of the problems that must be prioritized in a technology for recycling and adding high polymer materials.

Many of the foreign substances that express color in polymer resins containing ester functional groups are manufactured so as not to be easily separated in everyday living environments or conditions of use in order to prevent discoloration during the process of use or washing. In particular, dyes are It is mainly used to express the color of polyester fiber through a dye, and since the dye molecule in the colored fiber exists in the form of a complex with the polymer substrate, it is not easy to separate or remove the dye by simple contact with water or organic solvent.

As such, waste polyester resin containing a large amount of impurities that are difficult to separate is difficult to secure economic feasibility due to restrictions on the use and quality of recycled materials produced during physical and chemical recycling or the burden of the purification process for high added value of the product. . Therefore, colored waste polyester is one of polymers with very low utilization in the field of recycling or recycling, and is known as a waste resource that causes environmental problems because most of it is discarded or incinerated.

Therefore, it is necessary to develop a very effective and economical separation technology in removing color-expressing foreign substances from colored polymer resins containing ester functional groups. To this end, it is necessary to design a low-cost material that can effectively remove color-expressing foreign substances only by direct contact with a colored polymer resin containing an ester functional group, and to identify optimal conditions for a process using the same.

In addition, the polymer resin prepared through the above process may have some or trace impurities remaining, and in the process of adding high value through physical regeneration or chemical regeneration, the quality of the final product is improved through an easy and economical additional purification process before synthesizing the polymer material. In many cases, raw materials of the same or similar level are required.

Therefore, a material applied to remove foreign substances exhibiting color from a colored polymer resin containing an ester functional group must be inexpensive and low in hazard, and must not provide uneconomic factors for a regeneration process that can be performed sequentially.

On the other hand, conventional techniques for removing pigments from polymers containing ester functional groups include an adsorption method using a strong adsorbent such as activated carbon, a physical separation method such as filtration or distillation, and a chemical reaction such as oxidation, reduction, hydrolysis, or electrolysis. There are ways. These methods may be performed in parallel with a chemical depolymerization reaction or as a post-treatment process. U.S. Patent Publication Nos. 2015-0059103 and 2009-0133200 disclose techniques for removing dyes by directly applying an aromatic compound paraxylene as an extractant to a polymer containing an ester functional group, and Japanese Patent Registration No. 6659919 discloses carbon A technique for removing dye by contacting polyester with an extractant containing 90% by mass or more of glycol monoether having 8 to 15 atoms is known, but due to the reversible dyeing property of the dye, the decolorization effect is often fragmentary. However, the solvent itself used in the separation process is often harmful to the human body or expensive, and it is difficult to secure economic feasibility and produce eco-friendly products because the application temperature is very high.

In order to solve the above-mentioned problems, it is necessary to develop an extraction solvent that can effectively remove dyes from colored polymers containing ester functional groups, has relatively low harm to the human body and does not consume excessive energy, or a de-dyeing process using the same. The situation is.

On the other hand, following the problem of the above-described plastic pretreatment technology, there remains a problem of chemical recycling of recycling the plastic back into monomers as raw materials. Colored polymers containing ester functional groups can be monomerized through depolymerization, and various chemical reaction pathways have been developed. The monomers generated through decomposition can theoretically have properties equivalent to those of the raw materials used in the initial polymer synthesis. Depolymerization pathways that are industrially applied to recycle polyester include hydrolysis, glycolysis, methanolysis, and ammonolysis. Various chemical decolorization and depolymerization methods are widely used, ranging from complex processes that utilize only individual advantages.

The hydrolysis and methanolysis processes are used in many fields, but both reactions have limited quality and yield of products produced when the polyester resin is decomposed, the decomposition reaction time is long, and as a decomposition product, terephthalic acid (TPA) or dimethyl terephthalate (DMT), only one type is produced as a main product, and other types of terephthalate compounds are treated as by-product impurities. Therefore, in order to resynthesize the produced product into a high-quality polymer material, it is necessary to use a refining process that consumes excessive energy. configuration may be required.

Glycolysis is a depolymerization reaction in which glycol is added as a reactant. The most common example of glycolysis is a process for producing bis(2-hydroxyethyl) terephthalate (BHET) by adding an excessive amount of ethylene glycol (EG), one of the monomer raw materials. Since EG, a part of PET raw material, is used as a reactant, it has high thermodynamic compatibility with the reaction product, and it can be used by changing the existing polymerization process with only a small investment in equipment, and the raw material can be directly applied to production without separate chemical treatment. there is Glycolysis is generally carried out under reflux conditions of glycol, a reactant, and since the rate of decomposition from oligomers to monomers is slow and the distribution of products is wide even in the reaction equilibrium state, not only the reaction yield of the product but also the production yield are limited. It may exist, and a high-cost purification process may be necessary to separate the final product monomer from the reactant in high yield and high purity. As the reaction catalyst used, zinc acetate or lithium acetate is common.

These metal salt catalysts are not completely removed during the refining process and may remain in the product, and since even a small amount of metals harmful to the human body may be included in the regenerated monomer, products produced by reintroducing them, especially for food, medical, and other daily life There is an aspect that is difficult to utilize in the reprocessing of the material of the article. In addition, although the reaction proceeds at a high temperature in glycolysis, the recovery and purification process of the product generally follows a recrystallization method at a low temperature, resulting in high energy consumption and low cost and efficiency in the heat source supply method of the production process. There is a problem.

In carrying out the above-described glycolysis reaction, if the depolymerization reaction rate can be increased at a low temperature and an eco-friendly catalyst system with low harmfulness can be applied, not only efficient and economical operation, but also colored polymers containing ester functional groups that are released in large quantities can be produced. It is expected that it can be efficiently used in the manufacture of eco-friendly raw materials without restrictions on product quality or use.

US Patent Publication 2015-0059103 A1 (2015.03.05. Publication date) US Patent Publication 2009-0133200 A1 (2009.05.28. Publication date) Japanese Laid Open Patent Document 6659919 B2 (2020.03.04. Publication date)

The present invention is an environmentally friendly ester by adding a compound that simultaneously functions as an extractant for effectively separating and desorbing a dye from a polymer having an ester functional group containing a dye and an additive that improves the conversion rate of exchange esterification reaction. A method for decolorizing and depolymerizing colored polymers containing functional groups is provided.

In order to solve the above problems, the present invention provides a method for decolorizing and depolymerizing a colored polymer containing an ester functional group. Eluting a color-expressing foreign substance from a colored polymer resin containing a functional group;

[Formula 1]

(In Formula 1, R ₁ is any one selected from hydrogen, a hydroxy group, an aldehyde group, a carboxyl group, a C ₁ -C ₆ alkyl group, a C ₄ -C ₆ cycloalkyl group, and a C ₆ -C ₁₂ aryl group, n is any one integer from 0 to 5, and when n is 2 or more, R ₁ are the same or different, R ₂ is a C ₁ -C ₁₀ alkyl group, and m is any one of 1 to 6 It is an integer of, and when m is 2 or more, -OR ₂ are each the same or different.)

(b) adding at least one polyhydric alcohol and an exchange esterification reaction catalyst to the extraction mixture solution containing the polymer resin from which the foreign substances are eluted, followed by depolymerization in the presence of the catalyst.

The compound represented by Formula 1 is 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, 4-hydroxy-3,5-dimethoxybenzoic 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 prop-2-enoic acid, 4-enyl-2,6-dimethoxyphenol, 4-hydroxy-3-methoxybenzaldehyde, 3-hydroxy-4-methoxy Benzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde, 3,4-dihydroxy Benzaldehyde, 1-methoxy-4-[(E)-prop-1-enyl]benzene, 1-bromo-4-methoxybenzene, 2-tert-butyl-4-methoxyphenol, ethoxy Benzene, 1,3,5-trichloro-2-methoxybenzene, 1,3,5-tribromo-2-methoxybenzene, 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 It may be at least one selected from the group consisting of -[(E)-prop-1-yl]phenol and 2-methoxy-4-(prop-1-en-yl)phenol.

The colored polymer resin containing the ester functional group is a polymer resin that is colored by a foreign substance expressing one or more colors, and the extractant only extracts foreign substances that express color without changing the basic shape of the polymer resin. It may be a material that is selectively separated.

The colored polymer resin containing the ester functional group may be a colored polymer resin alone containing an ester functional group; Alternatively, it may be a mixed resin further comprising a colored polymer resin containing an ester functional group and at least one of polyethylene, polypropylene, polystyrene, polyvinyl chloride, cotton, hemp, wool, rayon, acetate, acrylic, nylon and spandex. .

The temperature of the extractant may be characterized in that the range of 70 to 200 ℃.

In one embodiment of the present invention, in the elution of a foreign substance expressing color from a colored polymer resin containing an ester functional group using the extractant, the extraction mixture containing the foreign substance and the extractant eluted from the polymer resin The solution is heated, and the vaporized extractant is continuously refluxed and resupplied, and the refluxed liquid extractant can be maintained in continuous contact with the colored polymer resin containing the ester functional group.

In another embodiment of the present invention, the extraction agent and the colored polymer resin containing the ester functional group may be brought into contact at a temperature of 0 to 50 ° C lower than the boiling point of the extraction agent.

In the step (a), the extractant is directly contacted with the colored polymer resin containing an ester functional group to elute the color-expressing foreign matter from the colored polymer resin containing an ester functional group, and then at least one of evaporation and distillation is included. In such a way, the extractant may be recovered from the extraction mixture containing the extractant and the color-expressing foreign matter.

As an embodiment of the present invention, the extractant is directly contacted with a colored polymer resin containing an ester functional group to elute a foreign material expressing color from the colored polymer resin containing an ester functional group, and then containing a decolorized ester functional group The polymer resin can be chemically depolymerized without a separate extractant separation process.

After depolymerization of the colored polymer resin containing the ester functional group decolorized in the step (a), color-expressing foreign substances remaining in the product resulting from the depolymerization reaction can be separated through a liquid-liquid extraction process. , The liquid-liquid extraction process may be performed in a temperature range of 25 to 150 °C.

The extractant may be added before or after the depolymerization reaction in step (b), and when the extractant is added before the depolymerization reaction, the total sum of the extractant including the added extractant is the repeating unit of the polymer resin. The ratio of the number of moles per mole can be from 0.1 to 50.

The catalyst for the exchange esterification reaction may be a metal-free organic compound catalyst or at least one selected from metal salts of Group 1A, Group 2A, and Group 2B metals, wherein the counter-ion of the metal salt is carbonic acid, bicarbonate, It can consist of organic anions selected from alkoxides or acetates.

The polyhydric alcohol is ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexane It may be at least one selected from diol, 1,7-octanediol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanediol, isosorbide, and 1,4-cyclohexane dimethanol.

The colored polymer containing the ester functional group is polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyglycolide or polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydric hydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) ( PHBV), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and Vectran.

In the step (a), the extractant containing the compound represented by Formula 1 has a ratio of 0.001 to 50 moles per mole of the repeating unit of the colored polymer resin having an ester functional group introduced, and in the step (b), the polyhydric alcohol Silver has a ratio of 1 to 50 moles per mole of the repeating unit of the polymer resin from which the foreign matter introduced is eluted, and the exchange esterification reaction catalyst has a ratio of 0.001 to 1 per mole of the repeating unit of the polymer resin from which the foreign material introduced in step (b) is eluted. It is characterized in that it is mixed so that the ratio of moles is.

In addition, the present invention can provide a method for purifying a glycol addition monomer obtained by depolymerization of a colored polymer having an ester functional group according to the above depolymerization method. In the purification method, (1) separating an extractant containing the compound represented by Formula 1 from a depolymerization reaction product by gas-liquid separation or liquid-liquid extraction; (2) after the step (1), a solid material separation step of separating a solid material containing a polymer having an unreacted ester functional group; and (3) a recovery step of recrystallizing and recovering the glycol addition monomer after separating the solids in step (2).

The solid material containing the unreacted ester functional group may be separated using physical filtration, and the step of separating the oligomer prior to recrystallization of the glycol addition monomer in step (3) may be performed first.

The compound used as an extractant in the present invention lowers or hinders the mutual attraction between the colored polymer resin containing an ester and the dye dyed, so that the colored polymer resin containing an ester functional group is very quickly and effectively than the extractants reported by the prior art. It is possible to remove the dye from the dye, and at the same time, it is applied to the depolymerization reaction without a separate process of separating the extractant from the polymer resin after the decolorization process, and has a remarkable effect of improving the conversion rate.

Therefore, it is possible to produce glycol addition monomers (e.g. bis(2-hydroxyethyl)terephthalate), which is a raw material for polymer resynthesis or before production, from colored polymers containing ester functional groups in high yield and high purity, High-purity bis(2-hydroxyethyl)terephthalate (BHET) using polyethylene terephthalate (poly(ethyleneterephthalate), PET), a polymer discharged after use, or waste polyester fiber as raw materials It can be usefully used for large-scale production of regenerated monomers such as

1 shows a process of dedyingization and depolymerization of a colored polyester resin according to an embodiment of the present invention.
Figure 2 shows changes in products produced from de-dying, depolymerization and purification processes of colored polyester resins according to an embodiment of the present invention.

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

Throughout the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

The present applicant has completed the present invention by focusing on the fact that the extractant used to remove color-expressing foreign substances from the colored polymer resin has characteristics that do not participate in the chemical depolymerization reaction, and the colored polymer containing an ester functional group according to the present invention The decolorization and depolymerization method for the conventional colored polymer containing an ester functional group is a recycling target in that the decolorization reaction following the decolorization of the colored polymer resin can be performed in one-step according to the input of the extractant in a single reactor. In this case, it is differentiated from the method of individually performing decolorization and depolymerization reaction processes.

Hereinafter, a method for decolorizing and depolymerizing a colored polymer having an ester functional group according to an embodiment of the present invention and a method for purifying a glycol addition monomer obtained by depolymerization of a colored polymer having a functional ester group according to the decoloring and depolymerization method to explain in detail.

The present invention relates to a method for decolorizing and depolymerizing a colored polymer containing an ester functional group, wherein (a) a colored polymer resin containing an ester functional group is directly brought into contact with an extractant containing a compound represented by Formula 1 below. Eluting a foreign material expressing color from the step;

[Formula 1]

(In Formula 1, R ₁ is any one selected from hydrogen, a hydroxy group, an aldehyde group, a carboxyl group, a C ₁ -C ₆ alkyl group, a C ₄ -C ₆ cycloalkyl group, and a C ₆ -C ₁₂ aryl group, n is any one integer from 0 to 5, and when n is 2 or more, R ₁ are the same or different, R ₂ is a C ₁ -C ₁₀ alkyl group, and m is any one of 1 to 6 It is an integer of, and when m is 2 or more, -OR ₂ are each the same or different.)

(b) adding at least one polyhydric alcohol and an exchange esterification reaction catalyst to the extraction mixture solution containing the polymer resin from which the foreign substances are eluted, followed by depolymerization in the presence of the catalyst.

First, the extractant according to an embodiment of the present invention is an extractant for removing foreign substances that express color from a colored polymer resin containing an ester functional group, comprising at least one compound represented by Formula 1 above. characterized by

In the compound represented by Chemical Formula 1, at least one alkyl group is connected to an aromatic ring through a linker, and the linker has at least one oxygen.

In one embodiment of the present invention, the compound represented by Formula 1 is methoxy benzene, 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-tetra Methoxybenzene, 1,2,4,5-tetramethoxybenzene, 2-methoxyphenol, 1,3-dimethoxy-2-hydroxybenzene, 4-hydroxy-3,5-dimethoxybenzoic acid, 3-(4-hydroxy-3,5-dimethoxyphenyl)prop-2-enal, 4-hydroxy-3,5-dimethoxybenzaldehyde, 4-hydroxy-3,5-dimethoxyaceto Phenone, 3-(4-hydroxy-3,5-dimethoxyphenylprop-2-enoic acid, 4-enyl-2,6-dimethoxyphenol, 4-hydroxy-3-methoxybenzaldehyde, 3-hydroxy-4-methoxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde Hyde, 3,4-dihydroxybenzaldehyde, 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-methoxybenzene, 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-benzo Dioxol, 4-methoxy-2-[(E)-prop-1-yl]phenol, 2-methoxy-4-(prop-1-en-yl)phenol, etc. It may be one or more selected from the group consisting of.

The colored polymer resin containing the ester functional group is a polymer resin that is colored by foreign substances expressing one or more colors, and the extractant selectively selects only foreign substances that express color without changing the basic shape of the polymer resin. It is characterized in that it is separated and removed.

In addition, as an extractant for removing color-expressing foreign substances from the colored polymer resin containing an ester functional group according to the present invention, among the compounds represented by Formula 1, those present in a liquid phase having a melting point lower than the extraction temperature may be used, and the dye It is advantageous to have low viscosity and fluidity so that diffusion can occur quickly.

In addition, the extractant according to the present invention is useful as an extractant for removing foreign substances such as colored pigments and dyes from a colored polymer resin containing an ester functional group, wherein the polymer containing an ester functional group is used alone or in a mixed resin. In addition, at least one of a plastic material such as polyethylene, high density polyethylene, low density polyethylene, polypropylene, polystyrene, polyvinyl chloride, etc., or a fiber such as cotton, hemp, wool, rayon, acetate, acrylic, nylon, spandex, etc. It may be in the form of a mixed polymer resin containing the ester functional group included. For reference, other polymers mixed with the polymer containing the ester functional group listed as examples are only examples and are not limited to those listed above.

The extractant may be characterized in that the temperature is in the range of 70 ℃ to 200 ℃ through heating, etc., and elutes the dye by directly contacting the colored polymer resin containing an ester functional group. The elution process may extract the dye through a single or repeated process.

The extraction temperature of foreign matter exhibiting color from the colored polymer resin containing the ester functional group may be carried out at 70 to 200 ° C, but more preferably at 120 to 150 ° C. If the temperature is less than 70 ℃, the elution rate proceeds slowly and the effect of extraction may be limited, and if the temperature exceeds 200 ℃, the energy consumption may be very high.

In addition, according to one embodiment of the present invention, in separating the dye from the colored polymer resin containing an ester functional group using the extractant, the extraction mixture solution containing the dye is heated and the extractant vaporized therefrom is continuously It is refluxed and resupplied so that the refluxed liquid extractant is maintained in continuous contact with the polymer resin containing an ester functional group, thereby enabling effective removal of dyed dyes.

In addition, in order to reflux only the extractant in the extraction mixture containing the extractant and foreign matter eluted from the polymer resin in addition to the polymer resin, the temperature of the heating unit may be maintained at a temperature close to the boiling point of the extractant. The contact temperature (or extraction temperature) between the polymer and the extractant may be determined by the amount of heat applied to the heater and the reflux rate of the extractant, which may affect extraction performance. It may be desirable to proceed with the extraction so that the contact temperature between the polymer and the extractant is maintained or controlled at a temperature lower than the boiling point of the extractant by about 0 to 50 ° C.

As an embodiment of the present invention, after the extraction process in step (a), the polymer resin containing the bleached ester functional group may be in a state in which the extractant is absorbed, and the residual extractant is separated by a method such as evaporation or drying. It is possible to obtain a decolorized polymer resin product, and the extraction mixture solution containing foreign substances and extractants eluted from the polymer resin in addition to the polymer resin is subjected to an additional evaporation or distillation process to recover most of the initially applied extractant. there is.

As another embodiment of the present invention, the polymer resin containing the ester functional group decolorized after the extraction process in step (a) does not go through the extractant recovery process, and the polymer resin in which the extractant in step (b) is absorbed Depolymerization may be performed by introducing the raw material into a chemical reactor. The extractant does not directly participate in the depolymerization reaction, and the type or amount added should not have an adverse effect on the performance of the depolymerization reaction, and it may be advantageous to not form a thermodynamically unstable phase under reaction conditions.

In addition, the compound represented by Formula 1 included in the extractant, as an additive, greatly reduces the activation energy of the depolymerization reaction for converting the colored polymer raw material containing an ester functional group into a glycol addition monomer, thereby increasing the depolymerization reactivity of the colored polymer, Selectivity of useful products can be increased. Therefore, in the present invention, a one-step configuration in which the decolorized polymer resin is directly applied to depolymerization without a separate extraction agent recovery or removal process or a simple sequential linkage of the decolorant-reaction is possible, and in this case, at a low temperature The performance of the reaction (conversion rate and monomer yield) can also be improved through the depolymerization reaction.

Meanwhile, the present invention is capable of separating a small amount of unextracted residual dye in the reaction product through a liquid-liquid extraction process after chemical depolymerization is performed on the polymer resin containing the ester functional group decolorized in step (b). there is.

At this time, a hydrophilic solvent including water may be additionally added to the reaction product for efficient separation of the dye and recovery of the monomer product. It is characterized by the fact that most of them are distributed.

The amount of the extractant may be adjusted by adding before or after the depolymerization reaction, but when added before the depolymerization reaction, the total sum of the extractant including the added extractant is 0.1 to 50 moles per mole of the repeating unit of the polymer; Preferably, the number of moles per mole of the repeating unit may be adjusted to be 1 to 5. If the addition amount of the extractant is added in a ratio of less than 0.1 moles per mole of the repeating unit of the polymer, the boundary region of the liquid-liquid phase equilibrium is unclear after the reaction is completed, so that the residual dye cannot be extracted into the organic phase, and 50 per mole of the repeating unit of the polymer When added in a molar ratio exceeding , the performance of the depolymerization reaction may deteriorate due to excessive dilution of the reactants.

The liquid-liquid extraction process may be carried out while maintaining the temperature in the range of 25 to 150 °C, more preferably in the range of 50 to 100 °C.

In addition, in the present invention, in order to additionally remove dyes or residual organic foreign substances in the depolymerization reaction product prepared as described above, only the aqueous layer is separated, the extractant is further added, and then the liquid-liquid extraction process is repeated. can

In addition, methods such as heating, drying, distillation, and evaporation may be used to separate and concentrate foreign substances such as dyes while recovering an extractant from the organic phase separated and discharged in the liquid-liquid extraction process.

In the method for decolorizing and depolymerizing colored polymers containing ester functional groups of the present invention, in the step (b), at least one polyhydric alcohol is used as a raw material for the glycolysis reaction, and an existing catalyst such as zinc acetate is used as the reaction catalyst. However, salts composed of Group 1A, Group 2A, or Group 2B metal cations and organic anions such as carbonic acid, bicarbonate, alkoxide, or acetate as counter-ions can also be used as catalysts. A non-metallic organic compound catalyst composed of may be used.

Since a low-cost catalyst containing various types of metals or an organic catalyst capable of decomposition at high temperatures can be selected as a reaction material, it is easy to secure economic feasibility by reusing and recovering materials or to control impurities. Accordingly, the present invention is characterized in that the reactivity of depolymerization can be maintained at a high temperature at a low temperature and the purity, yield and reaction selectivity of the depolymerized monomers are improved.

In addition, the method for decolorizing and depolymerizing colored polymers containing ester functional groups according to the present invention has a simple process, high product yield and easy purity management, an eco-friendly process, and economical efficiency because a low-cost catalyst can be used. Since it is easy to secure, it can be a technology with high utilization value in related chemical and environmental industries.

The method of the present invention is useful for depolymerization of a colored polymer containing an ester functional group, wherein the colored polymer containing an ester functional group is used alone or in the form of a mixed waste plastic, such as polyethylene, high density polyethylene, low density polyethylene, polypropylene, or a combination thereof. It may be in a mixed form with a colored polymer containing the ester functional group. Other polymers mixed with the colored polymer containing the ester functional group listed as examples above are merely examples and are not limited to those listed above.

In addition, the colored polymer containing an ester functional group may be a polymer formed by condensation polymerization of a dicarboxylic acid and a dialcohol, wherein the dicarboxylic acid is terephthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, or diphenyl ether dicarboxylic acid. boxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, trimellitic acid, It is selected from the group consisting of pyromellitic acid and combinations thereof, and the dialcohol is ethylene glycol, trimethylene glycol, 1,2-propanediol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, decanmethylene glycol, dodecamethylene glycol , 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, di(tetramethylene) glycol, tri( tetramethylene) glycol, polytetramethylene glycol, pentaerythritol, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, and combinations thereof.

For example, the colored polymer containing the ester functional group is polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyglycolide or polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL) , polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalor rate) (PHBV), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), Vectran, and combinations thereof.

One of the most common examples of the colored polymers containing the ester functional group is polyethylene terephthalate, and in this case, the starting materials for preparing the polymer are terephthalic acid or a derived monomer thereof, and ethylene glycol.

The colored polymer containing an ester functional group used in the present invention may be in a state containing various impurities rather than in a pure state. For example, a mixture of debris including, but not limited to, bottle caps, adhesives, paper, residual liquid, dust, or combinations thereof, in addition to colored polymers containing ester functional groups, may be used as a raw material for depolymerization.

In the method for decolorizing and depolymerizing a colored polymer containing an ester functional group according to the present invention, the colored polymer containing the ester functional group may be contained in about 0.1 mass% to about 70 mass% of the reaction raw material. If an amount less than 0.1% by mass is initially added, it may be difficult to secure economic feasibility, and if an amount greater than 70% by mass is added, mass transfer may be limited and the reaction rate may be significantly lowered.

The polyhydric alcohol for glycolysis depolymerization of the colored polymer containing the ester functional group is a compound having at least two or more alcohol functional groups, and more specifically, includes a compound having two or more hydroxyl groups such as a secondary linear alcohol. However, it is not particularly limited thereto.

The polyhydric alcohol may be used in a ratio range of 1 to 50 moles per mole of the repeating unit of the polymer.

Examples of the polyhydric alcohol having at least two or more alcohol functional groups according to the present invention include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl- 1,5-pentanediol, 1,6-hexanediol, 1,7-octanediol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanediol, isosorbide and 1,4-cyclohexane It may be one or more selected from the group consisting of dimethanol and the like.

As an example of the exchange esterification reaction catalyst according to the present invention, a metal-free organic catalyst may be used. As a non-limiting example of the organic type catalyst, linear amine-based (eg ethylenediamine, diethylenetriamine, tris (2-aminoethyl) amine, tetraethylenepentamine), amide-based (eg acetamide) , guanidine-based (eg triazabicyclodecene), imidazole-based (eg 2-ethyl-4-methylimidazole), urea-based (eg urea, 1,1-dimethylurea, 1,3- dimethylurea), aromatic amines (eg, benzenedimethaneamine), and cycloalkyl amines (eg, cyclohexylmethylamine, dimethylcyclohexylamine).

As another example of the catalyst according to the present invention, a salt composed of 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 used as the catalyst.

Group 1A ions used as the catalyst include lithium (Li ⁺ ), sodium (Na ⁺ ), potassium (K ⁺ ), group 2A metal magnesium (Mg ²⁺ ), calcium (Ca ²⁺ ), and group 2B metal include zinc (Zn ²⁺ ) and the like may be present, but are not particularly limited.

The amount of the catalyst may be used in a range of 0.001 to 1 mole per mole of the repeating unit of the polymer, preferably 0.01 to 0.1 mole per mole of the repeating unit.

As described above, the compound represented by Chemical Formula 1 is used not only as an extractant but also as an additive during the depolymerization reaction to increase the depolymerization reactivity of the colored polymer containing an ester functional group and to increase the selectivity of a useful product.

The amount of the additive containing the compound represented by Formula 1 may be used in a range of 0.001 to 50 moles per mole of the repeating unit of the polymer, preferably 0.1 to 10 moles per mole of the repeating unit.

The method for decolorizing and depolymerizing polymers according to the present invention provides a rapid method for depolymerizing colored polymers containing ester functional groups in the range of 100 to 200 °C, preferably in the range of 130 to 160 °C. As a result, the decolorization and depolymerization method of colored polymers containing ester functional groups provided herein can proceed at a lower temperature than conventional methods, enabling energy saving, and used catalysts and additives are recovered through a separate recovery process. It is economical because it can be reused.

In addition, the decolorization and depolymerization of the colored polymer of the present invention may be performed at atmospheric pressure, but may be performed in a pressurized form according to the formation of vapor pressure of the added additive or reactant.

In the method described herein, the depolymerization reaction time may vary depending on the amount of polymer used, but may be carried out according to the reaction time of 0.5 to 12 hours, and the reaction time of 0.5 to 4 hours is required to minimize the yield of by-products. may be desirable.

After the reaction, a process of separating and removing unreacted polymeric materials from the reaction mixture by filtering may be additionally performed.

Meanwhile, the present invention provides a method for purifying glycol addition monomers obtained by decolorization and depolymerization.

A method for purifying glycol-added monomers obtained by the decolorization and depolymerization method according to the present invention includes (1) separating the compound represented by Chemical Formula 1, which is an additive, from a depolymerization reaction product by gas-liquid separation or liquid-liquid extraction; ;

(2) after step (1), a solid material separation step of separating a solid material containing a colored polymer having an unreacted ester functional group; (3) a recovery step of recrystallizing and recovering the glycol addition monomer after separating the solids in step (2);

The gas-liquid separation of the additive may be performed separately from the reaction, or may be performed continuously after the reaction is completed. For example, using a pre-installed condenser maintained at a low temperature, the vaporized additive is condensed and refluxed into the reactor, and after the reaction is completed, the temperature is increased or maintained, but the condensed and refluxed additive is changed to the outside instead of inside the reactor can be separated by

The liquid-liquid extraction method is separation by adding water for recovery and purification of the target product. When water is added, a phase separation boundary is clearly generated, and most additives can be physically separated by separating only the organic layer at a low temperature. Additives that may remain in the aqueous phase after separation have very limited solubility when the water content is increased or the temperature is lowered, so most of them can be separated and recovered. Most of the product can be recovered through crystallization, and trace amounts of additives that may remain in the purified target product can be easily and completely removed by heating and drying at 50 to 150 ° C., preferably by heating and drying under vacuum.

In the gas-liquid phase separation for additive recovery according to the method described herein, a separate step of increasing the temperature of the reactor after the reaction to be higher than the reaction temperature so that some or all of the additives can be vaporized or volatilized is distilled and separated to the outside. include method For additive separation by liquid-liquid extraction, it is most economical to use water, but a hydrophilic material capable of inducing a thermodynamically unstable phase with an additive may be used, which may be glycol or diol used as a reactant. there is.

The solids containing the colored polymer containing the unreacted ester functional group may be removed before or after completion of the reaction through various physical methods such as precipitation, filtration, flocculation, flotation, and compression after the depolymerization reaction, and may be reintroduced into the depolymerization reaction. can In the case of the removal method using filtration, a filter having micropores having a sub-particle size of the unreacted polymer may be used, and pressurization or decompression may be performed in parallel to increase the flow rate of the filtrate.

The method for recovering the glycol addition monomer through the recrystallization process is more preferably performed after removing the unreacted material according to the reaction, and at a temperature higher than room temperature, such as in the range of 60 to 120 ° C., preferably in the range of 90 to 110 ° C. Temperature water or a solvent required for crystallization of the desired product may be used, but the step of separating the oligomer by filtration may be added. The filtrate may be maintained at a low temperature and recovered as a product through recrystallization, and physical separation and recrystallization may be repeated to control the concentration of impurities in the product. The step of separating the oligomer before recrystallization of the glycol addition monomer in step (3) may be performed first.

On the other hand, in constructing the reaction system according to the decolorization and depolymerization method according to the present invention, a non-metallic catalyst is used or a Group 1A or Group 2A metal cation and a counter-ion are organic such as carbonic acid, bicarbonate, alkoxide or acetate. When a metal salt composed of anions is used as a catalyst, product hazards caused by residual metal components are low and impurity concentration control can be much easier.

Hereinafter, the details of the process of the present invention will be described through Examples, Comparative Examples and Experimental Examples. This is a representative example related to the present invention, and it is revealed that the scope of application of the present invention cannot be limited only by this.

Polyester waste fiber raw material

raw material 1

A dark navy fleece jacket made of 100% polyester, which was discarded after consumption, was washed twice using a surfactant, and then washed using excess ethanol and distilled water, respectively. After drying the washed clothing until no residual moisture remains, it was cut into pieces with a side size of 3 cm or less to prepare waste fiber raw materials.

raw material 2

It has the molecular structure of Figure 1 below, and the red azo disperse dye disperse red 1 (N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline) has a salt solution concentration of 1% (o.w.f.; On the weight of fiber), red polyester fiber (supplied by Ditec Research Institute) dyed and reduced and washed was cut into pieces with a side size of 3 cm or less to prepare waste fiber raw materials.

[Figure 1]

raw material 3

Disperse red 9 (1-(methylamino)anthraquinone), an anthraquinone-based disperse dye with a molecular structure shown in Figure 2 below, is dyed and reduced and washed with a salt solution concentration of 1% (o.w.f.; on the weight of fiber). Polyester fiber (supplied by Ditek Research Institute) was cut into pieces with a side size of 3 cm or less to prepare waste fiber raw materials.

[Figure 2]

[Experiment of decolorization and depolymerization of colored polyester resin]

Experimental Example 1: Preparation of dedyed polyester raw material

About 10 g of pre-quantified colored polyester waste fiber raw material was put into a 250 ml flask containing 200.0 g of anisole (methoxybenzene) heated and maintained at 130 ° C in advance, and stirred for 10 minutes at 300 rpm using a magnetic stirrer to dye the dye. was extracted. After removing the mixed solution colored by the eluted dye, 150 g of anisole maintained at the same temperature was added again to elute the dye, and the above process of eluting the dye was repeated twice more for washing. Thereafter, the polyester fibers were recovered, transferred to a glass evaporating dish, placed in a vacuum dryer maintained at 60° C. under vacuum (≤ 2 mmHg), and then dried for 12 hours or more to obtain about 10 g of partially bleached fibers as a raw material for depolymerization. prepared. The decolorized fiber was measured for L* a* b* value using a spectrophotometer, and the effect of decolorization was observed compared to that measured for the original fiber.

Experimental Example 2: High-temperature glycolysis without additives

(a) Depolymerization reaction: About 10 g of the raw material prepared from waste colored polyester fiber and about 38.8 g of ethylene glycol (ratio of 12 moles per mole of terephthalate monomer in the polymer), a dihydric alcohol polar solvent, were put into a 3-neck flask and atmospheric pressure After installing a reflux condenser, stirring was started using a magnetic stirrer.

When the reaction mixture reached 197 ° C or the reflux temperature, about 0.114 g of zinc acetate catalyst was added to initiate the catalytic reaction, and the reaction mixture was continuously stirred for 2 hours while the reaction temperature was kept constant within ± 1 ° C. The reaction was carried out using a condenser exposed to

At the end of the reaction, a small amount of the reaction mixture was taken and prepared as a sample for quantification. The reaction yield of the depolymerized monomer and dimer was measured using high-performance liquid chromatography (HPLC with C18 column, UV detector (λ=254 nm)) calibrated with each standard sample.

As a mobile phase for HPLC analysis, a mixed solution with a volume ratio of methanol:water of 70:30 was used, and the total flow rate was maintained at 0.7 ml/min. Except for a small amount of samples taken for quantification, all reaction mixtures were filtered using a cellulose filter paper (pore size: 3 μm). On the filter paper, solid compounds other than monomers, such as dimers, oligomers, and unreacted polymers, and some dyes were obtained as solid content.

The yield of the products in the reactants was calculated by the following equation.

- Yield of monomer, Y _BHET (%) = M _BHET / M ₀ × 100

- Yield of dimer, Y _Dimer (%) = M _Dimer /M ₀ × 100

- Yield of oligomer, Y _Oligomer (%) = M _Oligomer /M ₀ × 100

- Yield of by-product (MHET), Y _MHET (%) = M _MHET /M ₀ × 100

Here, M _BHET , M _Dimer , M _Oligomer , and M _MHET represent the number of moles of terephthalate functional groups of BHET, dimer, oligomer, and MHET quantified by HPLC, respectively, and M ₀ represents the number of moles of repeating units in the input polymer structure. .

(b) Recovery of depolymerization products: After leaving the reaction mixture solution containing the monomers in a storage room maintained at 4°C for 12 hours, the crystallized solid phase is subjected to the above physical filtration method to remove a large amount of water, and then the solid content was taken as

The obtained solid content was again transferred to a vacuum dryer maintained at 60° C. and vacuum dried for 12 hours or longer to obtain a depolymerized product containing a high concentration of monomer (BHET).

(c) Measurement of chromaticity of depolymerized product: After taking about 200 mg of the obtained product, a 13 mm disc was spectroscopically analyzed using a pellet manufacturing mold (Pike Evacuable KBr Die Kit) and a hydraulic press (Hydraulic Press, Pike CrushIR) (applied pressure: 10 tons). It was prepared as a sample for colorimetric measurement. The color of the prepared disk sample was measured using a spectrophotometer (manufacturer: Konica Minolta, model name: CM-3600A) and obtained as L* a* b* values. The value expressed as L* a* b* is the coordinate value of the color space standardized by the International Commission on Illumination (CIE), and L* is expressed as 0 (black) to 100 (white) representing lightness. It is a numerical value, and a* and b* are numerical values expressed along the complementary axes of red (100)/green (-100) and yellow (100)/blue (-100), respectively.

Experimental Example 3: Decolorization and Depolymerization of Colored Polyester Resin

About 10 g of pre-quantified colored polyester waste fiber raw material was put into a 250 ml flask containing 200.0 g of anisole (methoxybenzene) heated and maintained at 130 ° C in advance, and stirred for 10 minutes at 300 rpm using a magnetic stirrer to dye the dye. was extracted. After removing the mixed solution colored by the eluted dye, 150 g of anisole maintained at the same temperature was added again to elute the dye. The above process of eluting the dye was repeated twice more, and then the bleached fiber that had not been dried was washed. prepared. After adding anisole so that the total mass of anisole added to the color-removed waste fiber raw material is 22.5 g (ratio of 4 moles per mole of terephthalate monomer in the polymer), about 38.8 g of ethylene glycol, a dihydric alcohol polar solvent, A depolymerization reaction product was prepared by adding 12 moles per mole of terephthalate monomer in the polymer. When the reaction mixture was heated to reach the reflux temperature, the reaction proceeded in the same manner as in the depolymerization method of Comparative Example 1 (a), except that about 0.20 g of potassium acetate catalyst was added to initiate the catalytic reaction.

After completion of the reaction, about 200 g of distilled water at 95 to 100 ° C. was added to the filtrate obtained from the filtration. Thereafter, the mixture was transferred to a container maintained at a constant temperature of 75° C. and stirred, and the stirring was stopped after 1 hour to induce phase separation. After separating only the aqueous layer from the organic phase layer containing most of the dye and extractant, a BHET product was obtained through the same depolymerization product recovery method as in Comparative Example 1 (b), and the same method as in Comparative Example 1 (c) was applied. Pellets were prepared using a spectrophotometer, and L* a* b* values were measured. 1 is a diagram illustrating the process of Experimental Example 3.

Dye removal effect according to the type of extractant

Example 1

The navy polyester fiber of Raw Material 1 was decolored through the de-dyeing process of Experimental Example 1, and the L* a* b* value was measured using a spectrophotometer.

Example 2

The red polyester fiber dyed with the azo dye of Raw Material 2 was decolored through the de-dyeing process of Experimental Example 1, and the L* a* b* value was measured using a spectrophotometer.

Example 3

The red polyester fiber dyed with the anthraquinone-based dye of Raw Material 3 was decolored through the de-dying process of Experimental Example 1, and the L* a* b* value was measured using a spectrophotometer.

Comparative Example 1

A decolorized fiber was prepared in the same manner as in Example 1, except that para-xylene was used instead of anisole as an extractant, and L* a* b* values were measured using a spectrophotometer. did

Comparative Example 2

A decolored fiber was prepared in the same manner as in Example 1, except that methoxycyclohexane was used instead of anisole as an extractant, and the L* a* b* value was measured using a spectrophotometer. .

Example 4

A decolored fiber was prepared in the same manner as in Example 1, except that 1,2-dimethoxybenzene was used instead of anisole as an extractant, and L* a was used using a spectrophotometer. *b* values were measured.

Example 5

A decolored fiber was prepared in the same manner as in Example 1, except that 1,4-dimethoxybenzene was used instead of anisole as an extractant, and L* a was used using a spectrophotometer. *b* values were measured.

Example 6

A decolored fiber was prepared in the same manner as in Example 1, except that ethoxybenzene was used instead of anisole as an extractant, and L* a* b* values were measured using a spectrophotometer.

Example 7

A decolored fiber was prepared in the same manner as in Example 1, except that guaiacol was used instead of anisole as an extractant, and L* a* b* values were measured using a spectrophotometer.

In Examples 1, 4 to 7 and Comparative Examples 1 to 2, decolorization was performed by applying the same conditions except for the extractant so that the decolorization effect of the extractant could be easily distinguished. The temperature of the extractant was kept constant at 130 ° C, and the blue polyester fiber of Raw Material 1 was used as a polymer for decolorization. Table 1 below shows a comparison of the color coordinate (L* a* b*) values measured using a spectrophotometer for each of the manufactured bleached polyester fibers.

division extractant type L a b raw material 1 - 18.6 1.8 -9.9 Comparative Example 1 p-Xylene 55.0 -7.1 -21.4 Comparative Example 2 Methoxycyclohexane 29.3 -1.9 -24.1 Example 1 Anisole 86.3 0.7 0.9 Example 4 1,2-Dimethoxybenzene 81.1 -2.6 -3.5 Example 5 1,4-Dimethoxybenzene 85.5 0.1 1.5 Example 6 Ethoxybenzene 71.7 -5.9 -11.8 Example 7 Guaicol 89.7 1.5 2.6

For reference, in some prior patents (US 7959807B2, US 2015/0059103A1), it is known that aromatic compounds such as paraxylene can be usefully utilized as an extractant for removing dyes from colored polyester resins. Paraxylene is a relatively stable non-polar hydrocarbon compound with a boiling point of about 138°C. Under the above-described extraction conditions, when paraxylene was applied as an extractant and decolorization was performed through contact with colored polyester fibers (Comparative Example 1), some partial discoloration was observed, but it was visually observed that the dye remained in the fibers. could be easily verified. When measured using a spectrophotometer for polyester fibers bleached by paraxylene, the lightness (L) value is about 55, and the values of a and b, which represent the complementary color axis for color, also have a large negative deviation from the neutral value. (green and blue) were observed.

On the other hand, when the extractant presented in the present invention, that is, the extractant represented by Formula 1 (at least one alkyl group connected to an aromatic ring through a linker, and the linker having at least one oxygen) is used (Examples 1 and 4 to 7), the dye extraction effect was observed to be very high under the same conditions.

In addition, the lightness (L) values measured by the spectrophotometer for the decolorized polyester fibers prepared through the extractant having the chemical form presented in the present invention all showed values of 70 or more, indicating the complementary color axis for color. The values of a and b were also mostly measured close to neutral values.

In addition, when 1,2-dimethoxybenzene (Example 4) and ethoxybenzene (Example 6) were applied among the examples for the extractant according to the present invention, the effect of decolorization was observed to be somewhat low, which is alkoxy It is presumed that this is due to the structural steric hindrance of the compound derived from the position where the group is bonded to the aromatic ring and the number of carbon atoms constituting the alcohol group.

Methoxycyclohexane has a structure similar to that of the additive according to the present invention, but is a compound modified with a saturated cycloalkane having the same number of carbon atoms as the aromatic ring, which is the central functional group of the compound. When this was applied under the same extraction conditions (Comparative Example 2), it showed a very poor decolorization effect compared to other extractants having an alkoxy-linked cyclic unsaturated hydrocarbon (or aromatic) structure. Comparing the color coordinates (L* a* b*) values measured from the spectrophotometer for the fibers prepared by Raw Material 1 and Comparative Example 2 used, a slight change in coordinates occurred, but a significant degree of discoloration was observed. No vertical rise in L values or significant decreases (shifts in the direction of neutral values) in the absolute values for a and b were observed. Therefore, it can be seen that compounds other than the aromatic ring, which is the central functional group of the compound, have very little effect as an extractant.

Disperse dyes used in polyester resins are generally classified into azo-based or anthraquinone-based disperse dyes according to the type of chemical structure. Table 2 below shows the method of Experimental Example 1 for the colored polyester resins of Raw Materials 1 to 3 in which disperse dyes having different colors and shapes were introduced by adding anisole having the simplest structure among the compounds represented by Formula 1. It is shown by comparing the results of destaining according to the results. When destaining was performed by applying anisole as an extractant according to the method of Experimental Example 1, colored polyester fibers into which dyes having different chemical structures were introduced, such as azo dyes (Example 2) or anthraquinone dyes (Example 2). It was found that the de-dyeing effect was well expressed for all of the colored polyester fibers to which Example 3) was introduced.

textile color dyes introduced measuring fiber L a b Indigo Common (Unknown) raw material 1 18.6 1.8 -9.9 Example 1 86.3 0.7 0.9 Red Disperse Red 1 raw material 2 38.1 52.0 29.6 Example 2 91.9 3.6 5.7 Red Disperse Red 9 raw material 3 50.9 58.7 13.5 Example 3 93.9 1.0 2.0

Comparison of quality of products obtained from decolorization and depolymerization of colored polymer resins

In the above-described embodiments, an effective method for removing colored foreign substances from colored polyester raw materials by applying the extractant according to the present invention has been described. A polymer resin containing an ester bond from which color-expressing foreign substances are removed may be suitably used as a raw material for physical or chemical regeneration.

The following examples are based on an example of the above-described extraction method (Experimental Example 1) when the colored polyester raw material itself is applied to a generally known depolymerization reaction (glycolesis using a zinc acetate catalyst) (Comparative Example 3). When the partially bleached polyester raw material was applied to the same depolymerization reaction (Example 8), and when the raw material containing the extractant was added to the depolymerization reaction and the dye was additionally removed in the purification process (Examples 9 to 11) These are classified as , and are for comparative analysis of the characteristics of depolymerization under each condition and the quality of the final product manufactured.

Comparative Example 3

Without adding the additives represented by Chemical Formula 1 to the navy polyester fiber of Raw Material 1, high temperature (197 ° C.) depolymerization and purification were performed according to the procedure of Experimental Example 2 to obtain a monomer product, and a spectrophotometer was obtained. The L* a* b* value was measured for the product obtained using the product.

Example 8

By adding the additive represented by Chemical Formula 1 to the navy polyester fiber of Raw Material 1, a dye-free polyester raw material was prepared according to the procedure of Experimental Example 1. Without adding the additive represented by Formula 1 to the prepared dedyed polyester fiber, a high temperature (197 ° C.) depolymerization and purification process was performed according to the procedure of Experimental Example 2 to obtain a monomer product, obtained using a spectrophotometer L* a* b* values were measured for the product.

Example 9

The additive represented by Chemical Formula 1 was added to the navy polyester fiber of Raw Material 1, and a low-temperature (153 ° C.) depolymerization and purification process were performed according to the procedure of Experimental Example 3 to obtain a monomer product, using a spectrophotometer. L* a* b* values were measured for the obtained product.

Example 10

A monomer product was obtained in the same manner as in Example 9, except that the red polyester fiber dyed with the azo dye of Raw Material 2 was used.

Example 11

A monomer product was obtained in the same manner as in Example 9, except that the red polyester fiber dyed with the anthraquinone-based dye of Raw Material 3 was used.

The performance of the reaction evaluated by quantitative analysis of the product after the depolymerization reaction and the color coordinate values (L* a* b*) measured using a spectrophotometer after pelletizing the prepared monomer are shown in Table 3 below.

As the low-density polymer was applied as a raw material, depolymerization proceeded very rapidly in all cases, and it was observed that all fibers were decomposed within 30 minutes (conversion rate = 100%), but left for sufficient reaction time (2 hours). This allowed the reaction equilibrium to be reached.

division Raw material reaction
temperature Depolymerization reaction yield (%) Color coordinate values for monomers BHET dimer oligomer MHET L a b Comparative Example 3 raw material 1 197℃ 84.1 4.7 10.5 1.4 53.2 16.9 18.0 Example 8 raw material 1 197℃ 84.9 4.8 8.8 1.5 64.5 14.1 17.5 Example 9 raw material 1 153℃ 86.8 4.8 7.0 1.4 94.4 -0.3 0.5 Example 10 raw material 2 153℃ 86.9 4.6 6.8 1.7 92.4 1.6 3.7 Example 11 raw material 3 153℃ 87.6 4.8 5.6 2.0 94.2 0.2 2.3

In Comparative Example 3 to compare and explain the effects of the embodiments of the present invention, a dark navy polyester waste fiber raw material that had not undergone a bleaching process by an extractant was directly applied to the glycolysis reaction. The most commonly used zinc acetate catalyst was added to initiate the reaction at the reflux temperature of ethylene glycol (197°C), and when the final reaction time was reached, about 84.1% of the monomer (BHET) was obtained.

The BHET product obtained in Comparative Example 3 showed a color completely different from that of the starting raw material, navy polyester fiber, and the lightness (L) was about 53 in the color coordinate values measured by pelletizing and spectrophotometry. , the values of a and b representing the complementary color axis were measured as positive values close to 20. This indicates that the dye, which is an impurity that develops color, is not easily removed in the purification process (physical filtration and recrystallization) of the product.

In Example 8, depolymerization was performed in the same manner as in Comparative Example 3, but decolorization polyester fiber from which some impurities were previously removed through contact with anisole maintained at 130 ° C. for 10 minutes according to the extraction and washing process was applied as a raw material. will be.

In Example 8, after 2 hours of depolymerization, the yield of BHET was measured to be 84.9%, a slight increase compared to the case of Comparative Example 3. The color of the BHET prepared through the purification process became pale, but a high level of color was still observed due to residual foreign substances that were difficult to remove during the purification process. In the color coordinate values measured by a spectrophotometer after pelletizing it, the brightness was about 65, and the a and b values representing the complementary color axis were about 14 and 18, which were obtained compared to the case of applying the raw material without pretreatment (Comparative Example 13). This is a result indicating a slight improvement in terms of the effect of dye extraction.

In Example 9, the amount of the extractant was adjusted and applied to the depolymerization reaction without removing the extractant in the process of removing the color-expressing material using the extractant. Depolymerization was carried out at a low temperature enabling reflux of the extractant (anisole) added to the reaction.

In Example 9, in which the reaction was performed by adding anisole, the BHET obtained after 2 hours of depolymerization was about 87%, which was higher than the previous two cases. After separating high molecular weight substances such as dimers and oligomers from the reactants obtained from depolymerization through physical filtration, adding water to purify the monomers, and lowering the temperature of the mixture to 100 ° C or less, thermodynamically unstable phase separation occurred. When the boundary regions of the phases were clear, it was easy to see that the residual dye was distributed in high concentration in the upper layer (organic phase layer), which is the main constituent of the extractant. The asymmetric distribution of the dye was visually identifiable, and the process of liquid-liquid phase separation to separate the residual dye from the reaction mixture prepared after destaining and depolymerization in accordance with the process of Example 9 is shown in an example of FIG. same as bar

After separating the organic phase in which the color-expressing substance is highly concentrated, taking the aqueous phase, leaving it at low temperature (4 ℃) for a long time to proceed with the crystallization of the monomer, recovering it, and drying it to obtain high-purity BHET with a white color. Could. When the BHET obtained from the extraction process is contaminated by a color-expressing substance, a small amount of the extractant and water heated to 90 ° C. or higher are added again in a similar ratio to obtain a high-purity product, and the liquid-liquid extraction described above Most of the remaining foreign matter can be removed very effectively by using the method of repeating the process of

As a result of measurement with a spectrophotometer for the monomer product (BHET) obtained through the process of Experimental Example 3 (Examples 10 to 11) for colored polyester fibers into which azo dyes or anthraquinone dyes were respectively introduced, It was found that a sample with a brightness of 90 or more and an absolute value of a and b of 4 or less was produced. Figure 2 illustrates the forms of intermediate products and high-purity BHET that can be prepared from dedying, depolymerization, and purification processes from colored polyester resins in which colors are expressed by disperse dyes having different chemical structures. The pictures in the first two columns shown in FIG. 2 are magnified (100 times) observations of the fiber shape and the residual form of the dye before and after the dedying process using a stereo microscope, and the pictures in the last column are obtained by pelletizing the finally obtained monomer by a hydraulic press. It shows the solid samples processed into the form.

As in Examples 9 to 11, when a series of procedures consisting of decolorization (pretreatment), depolymerization (reaction), and purification (posttreatment) are applied to a commercial process for chemical regeneration of colored polyester, the color is obtained through pretreatment. Polyester polymer resin, from which a large number of foreign substances are removed, can be applied as a raw material for depolymerization reaction, and can be directly applied as a raw material for chemical regeneration process without removing a separate extractant. It is expected that a very economical monomer manufacturing process that can significantly reduce purification costs can be implemented because most of the foreign substances that exhibit color can be effectively removed after the reaction is completed.

Having described specific parts of the present invention in detail above, it will be clear to those skilled in the art that these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. . Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (12)

In the decolorization and depolymerization method of a colored polymer containing an ester functional group,
(a) eluting a foreign material expressing color from a colored polymer resin by directly contacting an extractant containing a compound represented by Formula 1 with a colored polymer resin containing an ester functional group;
[Formula 1]

(In Formula 1, R ₁ is any one selected from hydrogen, a hydroxy group, an aldehyde group, a carboxyl group, a C ₁ -C ₆ alkyl group, a C ₄ -C ₆ cycloalkyl group, and a C ₆ -C ₁₂ aryl group, n is any one integer from 0 to 5, and when n is 2 or more, R ₁ are the same or different, R ₂ is a C ₁ -C ₁₀ alkyl group, and m is any one of 1 to 6 It is an integer of, and when m is 2 or more, -OR ₂ are each the same or different.)
(b) adding at least one polyhydric alcohol and an exchange esterification reaction catalyst to the extraction mixture solution containing the polymer resin from which the foreign substances are eluted, followed by depolymerization in the presence of the catalyst; Methods for decolorization and depolymerization of colored polymers. According to claim 1,
The compound represented by Formula 1 is 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, 4-hydroxy-3,5-dimethoxybenzoic 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 prop-2-enoic acid, 4-enyl-2,6-dimethoxyphenol, 4-hydroxy-3-methoxybenzaldehyde, 3-hydroxy-4-methoxy Benzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde, 3,4-dihydroxy Benzaldehyde, 1-methoxy-4-[(E)-prop-1-enyl]benzene, 1-bromo-4-methoxybenzene, 2-tert-butyl-4-methoxyphenol, ethoxy Benzene, 1,3,5-trichloro-2-methoxybenzene, 1,3,5-tribromo-2-methoxybenzene, 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-en-yl] phenol, characterized in that at least one selected from the group consisting of 2-methoxy-4- (prop-1-en-yl) phenol, an ester functional group A method for decolorization and depolymerization of colored polymers comprising According to claim 1,
The colored polymer resin containing the ester functional group,
It is a polymer resin that is colored by a foreign substance that expresses one or more colors,
The method of decolorizing and depolymerizing a colored polymer containing an ester functional group, characterized in that the extractant selectively separates only foreign substances exhibiting color without changing the basic shape of the polymer resin. According to claim 1,
The colored polymer resin containing the ester functional group may be a colored polymer resin alone containing an ester functional group; or a colored polymer resin containing an ester functional group and at least one of polyethylene, polypropylene, polystyrene, polyvinyl chloride, cotton, hemp, wool, rayon, acetate, acrylic, nylon and spandex. A method for decolorizing and depolymerizing colored polymers containing ester functional groups. According to claim 1,
In the elution of color-expressing foreign substances from the colored polymer resin containing an ester functional group using the extractant, the extraction mixture solution containing the foreign substances and the extractant eluted from the polymer resin is heated, and vaporized therefrom. A method for decolorizing and depolymerizing a colored polymer containing an ester functional group, characterized in that the extracted extractant is continuously refluxed and resupplied, and the refluxed liquid extractant is maintained in continuous contact with the colored polymer resin containing an ester functional group. According to claim 1,
After depolymerization of the colored polymer resin containing the ester functional group decolorized in step (a),
A method for decolorizing and depolymerizing a colored polymer containing an ester functional group, characterized in that a foreign substance expressing color remaining in the product following the depolymerization reaction is separated through a liquid-liquid extraction process. According to claim 1,
The polyhydric alcohol is ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexane Ester, characterized in that at least one selected from diol, 1,7-octanediol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanediol, isosorbide and 1,4-cyclohexane dimethanol A method for decolorization and depolymerization of colored polymers containing functional groups. According to claim 1,
Colored polymers containing ester functional groups include polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyglycolide or polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxy Alkanoate (PHA), polyhydroxybutyrate (PHB), polyethylene adipate (PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV ), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and at least one selected from the group consisting of Vectran, characterized in that, decolorization of a colored polymer containing an ester functional group and depolymerization methods. According to claim 1,
In step (a), the extractant containing the compound represented by Formula 1 has a mole ratio of 0.001 to 50 per mole of the repeating unit of the colored polymer resin containing the ester functional group introduced,
In the step (b), the polyhydric alcohol has a ratio of 1 to 50 moles per mole of the repeating unit of the polymer resin from which the introduced foreign matter is eluted,
The exchange esterification reaction catalyst is characterized in that the foreign substances introduced in step (b) are mixed in a ratio of 0.001 to 1 mole per mole of the repeating unit of the eluted polymer resin, characterized in that it decolorizes and depolymerizes colored polymers containing ester functional groups. method. A method for purifying a glycol addition monomer obtained by depolymerization of a colored polymer having an ester functional group according to the decolorization and depolymerization method according to any one of claims 1 to 9,
(1) separating an extractant containing a compound represented by Formula 1 from a depolymerization reaction product by gas-liquid separation or liquid-liquid extraction;
[Formula 1]

In Formula 1,
The substituent R ₁ is any one selected from hydrogen, a hydroxyl group, an aldehyde group, a carboxyl group, a C ₁ -C ₆ alkyl group, a C ₄ -C ₆ cycloalkyl group, and a C ₆ -C ₁₂ aryl group,
Wherein n is any one integer from 0 to 5, and when n is 2 or more, R ₁ are each the same or different;
The substituent R ₂ is a C ₁ -C ₁₀ alkyl group,
The m is any one integer from 1 to 6, and when m is 2 or more, -OR ₂ is each the same or different.
(2) after the step (1), a solid material separation step of separating a solid material containing a polymer having an unreacted ester functional group;
(3) a recovery step of recrystallizing and recovering glycol-added monomers after separating solids in step (2); A method for purifying monomers. According to claim 10,
A method for purifying a glycol addition monomer obtained by decolorization and depolymerization of a colored polymer containing an ester functional group, characterized in that the solid material containing the unreacted ester functional group is separated using physical filtration. According to claim 10,
A method for purifying a glycol addition monomer obtained by decolorization and depolymerization of a colored polymer having an ester functional group, characterized in that the step of separating the oligomer before recrystallization of the glycol addition monomer in step (3) is performed first.

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