KR20220104886A - Extraction agent for removing impurities expressing color from monomers of polymer resins containing ester functional groups and purification method of monomers using the same - Google Patents

Abstract

The present invention relates to a method for purifying a polymer resin monomer comprising an ester functional group in which a compound represented by following chemical formula 1 or a mixture including the same is brought into contact with a monomer of a polymer resin including an ester functional group or a reaction mixture including a decomposed low molecular weight material to remove foreign substances including pigments or dyes from the polymer having an ester functional group or the decomposed low molecular weight reaction mixture.

Description

Extraction agent for removing impurities expressing color from monomers of polymer resins containing ester functional groups and purification method of monomers using the same}

The present invention relates to an extractant for removing a foreign substance expressing color from a monomer of a polymer resin containing an ester functional group, and a method for purifying the monomer using the same.

More specifically, a foreign material that expresses color may be contained in the monomer of the polymer resin containing an ester functional group, and in particular, a dye or pigment is included in the polymerized form of the polyester resin to exhibit color in the chemical depolymerization reaction. If some of the above-mentioned impurities are included in the monomers and low molecular weight reaction compounds obtained by Otherwise, various problems may occur, such as not controlling the uniform dispersion of the dye. Therefore, in the present invention, at least one alkyl group is connected to the aromatic ring through a linker, and the linker is selected by adding a hydrophobic organic compound having at least one oxygen to the monomer and the like through liquid-liquid phase separation. technology to separate

As the use of artificial synthetic fibers and plastics is gradually increasing in modern society, interest in recycling technologies for waste plastics discharged after consumption is increasing. In particular, a polymer material containing an ester functional group can be depolymerized in a form that can be used for resynthesis of the material through depolymerization or a high value-added raw material that can be applied to materials for other purposes. Monomer production technology based on the reaction route is being developed. The monomers generated through chemical decomposition can theoretically be manufactured with properties equivalent to those of raw materials used for initial polymer synthesis or with a purity that can be used for polymer polymerization, but the waste polymer materials discharged after use contain various types of foreign substances and And this can be the biggest cause of lowering the quality of the final product.

In particular, dye compounds that induce direct penetration into the polymer matrix, such as dyes or pigments, are manufactured through a series of physical and chemical pre- and post-treatment and dyeing processes as well as designing materials to prevent discoloration, so simple cleaning However, it is difficult to remove through the washing process, and it is not easy to chemically separate or isolate these compounds even from the products of depolymerization, that is, low molecular weight compounds containing a terephthalic acid structure.

Pigments are pigments that are dispersed in a solvent in the form of powder particles and are not soluble in water or oil, and dyes can be uniformly soluble in most solvents and have a very small particle size or molecular form. . Pigments are mostly applied to polymer resins through paint or printing methods, and dyes are used through a coloring process, and are mostly used to dye fibers or leather. Dyes are further classified into natural dyes obtained from plants, animals, or minerals, or artificial dyes synthesized artificially. Examples of artificial dyes include direct dyes, mordant dyes, reducing dyes, chromogenic dyes, dispersible dyes, reactive dyes, and the like. Azo-based and anthraquinone-based disperse dyes are most commonly used.

In obtaining a high-addition monomer by purifying a depolymerization reaction product of a polymer containing an ester functional group, as a prior art for obtaining a high-purity monomer from which a dye has been removed, an adsorption method using an adsorbent such as activated carbon, a physical separation method such as filtration or distillation, Chemical methods such as oxidation, reduction, hydrolysis, and electrolysis are applied. However, even a trace amount of a pigment compound is colored, and the effect is often very fragmentary due to the coloring characteristic of forming a complex with polymer monomers. Most of the things are difficult.

As a related prior art, Japanese Patent No. 4537288 discloses the manufacture of dimethyl terephthalate and alkylene glycol from dye-colored polyester fibers including a dye extraction process, a solid-liquid separation process, a depolymerization process, a transesterification process, and an active ingredient recovery process. How to do it is known. In the above patent, xylene and alkylene glycol are used as extraction solvents for extracting the dye from the dyed polyester fiber, and the dye is extracted and removed at 220° C. or higher above the glass transition point of the polyester. After the dye is extracted, the polyester fiber from which the dye is extracted is additionally added with alkylene glycol and a partial depolymerization reaction solution in the presence of a depolymerization catalyst to cause a depolymerization reaction and a depolymerization solution containing bis-ω-hydroxyalkyl terephthalate (BHAT) A process for obtaining is disclosed. However, it is undesirable to extract the dye before depolymerization because it is uneconomical and the extraction efficiency is low.

In addition, in Korea Patent No. 10-1142329, the step of contacting the oligomer solution obtained by depolymerization of polyester with an ion exchange resin to remove the catalyst in the oligomer solution, and the oligomer solution from which the catalyst has been removed is treated with activated carbon, activated clay, diatomaceous earth, etc. A technique for removing the colored material in the oligomer solution by adsorbing it to the bleaching agent is known. However, in the above patent, the amount of the bleaching agent used may be excessive, which is not economical.

In order to solve the above-mentioned problems, it is possible to effectively remove colored dyes or pigments from terephthalate derivatives generated from depolymerization of colored polymers containing ester functional groups or from the purification process of products, and excessive energy is not consumed. It is necessary to develop a material or process that prevents it.

Japanese Patent No. 4537288 (registered on June 25, 2010) Korean Patent Registration No. 10-1142329 (Registered on April 26, 2012)

In the present invention, an extractant capable of selectively extracting and removing foreign substances expressing a color present in the monomer by adding it to a monomer of a polymer resin containing an ester functional group, and a monomer of a polymer resin containing an ester functional group using the same An object of the present invention is to provide a purification method for purification.

In addition, in the present invention, the monomer of the polymer resin is in situ ( An object of the present invention is to provide a method for purifying a product by performing purification in-situ or by additionally adding one or more post-treatment processes.

In addition, an object of the present invention is to provide a method for producing a high-purity monomer or derivative compound of the polymer resin capable of controlling the purity of a product by continuously applying a repeated extraction process by adding a small amount of additive.

In order to solve the above problems, the present invention is an extractant for removing a foreign substance expressing color from a monomer of a polymer resin containing an ester functional group, and an ester functional group comprising a compound represented by the following Chemical Formula 1 It provides an extractant for removing foreign substances expressing color from a monomer of a polymer resin comprising a.

[화학식 1]

[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 an integer from 0 to 5, and when n is 2 or more, R ₁ is the same or different, and the substituent R ₂ is a C ₁ -C ₁₀ alkyl group, and m is 1 to It is an integer of any one of 6, and when m is 2 or more, -OR ₂ is the same or different.

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-hydroxyl-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-methoxybene Zaldehyde, 3,4-dihydroxybenzaldehyde, 1-methoxy-4-[(E)-prop-1-enyl]benzene, 1-bromo-4-methoxybenzene, 2-tert- Butyl-4-methoxyphenol, ethoxybenzene, phenol, 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, selected from the group consisting of 3-benzodioxole, 4-methoxy-2-[(E)-prop-1-yl]phenol, 2-methoxy-4-(prop-1-en-yl)phenol may be one or more of these.

In one embodiment of the present invention, the monomer of the polymer resin including the ester functional group may be characterized in that it is obtained from depolymerization of the polymer resin including the ester functional group.

In addition, the present invention is a purification method for producing a high-purity monomer by removing foreign substances from a monomer of a polymer resin containing an ester functional group. adding and mixing the compound represented by Formula 1 above; 2) inducing liquid-liquid phase separation by standing still the mixed solution in step 1); 3) separating and discharging the phase-separated liquid-liquid layer into the upper organic solution layer and the lower aqueous solution layer; A purification method for producing a monomer of

In another embodiment of the purification method of the present invention, in step 1), in addition to the compound represented by Formula 1, water or a hydrophilic liquid immiscible with the compound represented by Formula 1 containing foreign substances expressing the color It may be characterized in that it is added to the monomer.

In another embodiment of the purification method of the present invention, the monomer is a mixture after depolymerization obtained by depolymerizing a polymer resin containing an ester functional group, or a partially purified mixture after the depolymerization reaction. It may be characterized. .

In addition, in the purification method according to the present invention, further adding the compound represented by Chemical Formula 1 to the separated aqueous solution layer to further extract foreign substances that express color; may be repeated one or more times, and separated The method may further include adding water or a hydrophilic liquid immiscible with the compound represented by Formula 1 to the organic solution layer and mixing, followed by performing phase separation again.

In the purification method according to the present invention, the monomer of the polymer resin including the ester functional group may be recovered from the separated aqueous phase through recrystallization.

In addition, the present invention comprises the steps of: a) adding the compound of Formula 1 to a colored polymer resin containing an ester functional group; b) depolymerizing the polymer resin including the ester functional group; c) adding and mixing water or a hydrophilic solution immiscible with the compound represented by Formula 1 to the depolymerization reaction mixture obtained from the depolymerization reaction; d) inducing liquid-liquid phase separation by standing still the mixed solution in step c); e) separating and discharging the phase-separated liquid-liquid layer into an upper organic solution layer and a lower aqueous solution layer; Provided is a purification method for removing foreign substances to produce a high-purity monomer.

Also, in another embodiment of the present invention, it may be characterized in that the organic solvent is recovered through distillation from the organic solution layer separated and discharged in step e) and recycled.

According to the present invention, it is possible to purify the monomer of the polymer resin including the ester functional group with high purity.

In addition, according to the present invention, the monomer of the polymer resin is obtained by depolymerization of a colored polymer resin containing an ester functional group, and is a depolymerized monomer or an addition monomer (eg, BHET) having the same quality as before the production of the polymer resin. ) can be produced with high yield and high purity.

Since the extractant according to the present invention does not directly participate in the depolymerization reaction, when used for the purification of the monomer by the depolymerization reaction, it can be added before or after the depolymerization reaction, and thus the ease of use is high.

In addition, due to the extractant, it is possible to lower the affinity with the depolymerized low-molecular compound by controlling the non-covalent mutual attraction such as the hydrogen bonding force between the foreign material and the additive and the π-overlapping between the aromatic rings of the heterogeneous compound. Since the product, terephthalate compound, is distributed at a high concentration in the hydrophilic lower phase, the product can be purified with high purity through physical phase separation. It has the advantage of reducing energy consumption.

In the present invention, relaxed operating conditions can be applied compared to the existing separation process, the amount of energy loss can be minimized, a compound composed of eco-friendly materials is applied to each process, and the extractant and reaction product used are separately separated Since it can be recovered and reused through the process, it is possible to implement an environmentally friendly and economical purification process.

In addition, the extractant and purification method of the present invention do not require a complex process unit, and by using a simple and repetitive phase separation method, the purity of the depolymerized product can be increased, so that it can be applied to high-purity, high-yield purification technology by various forms or methods. It is possible.

In addition, even when the depolymerized and purified monomers are reused as raw materials for plastics or resin products by polymerization, the quality and use are not limited, so a perfect chemical recycling technology can be realized.

1 shows a thermodynamic phase equilibrium state of a binary compound composed of anisole, which is a kind of extractant according to the present invention, and a hydrophilic solvent (water or ethylene glycol).
2 is a ¹ H NMR spectrum of organic pigments and purified depolymerized monomer products extracted during depolymerization and product purification of colored waste PET polymers in some Comparative Examples and Examples of the present invention.
3 is a ¹ H NMR spectrum of an organic dye and a purified depolymerized monomer product extracted during depolymerization and product purification of colored polyester fibers according to some examples of the present invention.

Unless defined otherwise, 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 those well known and commonly used in the art.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

The present invention provides an extractant comprising a compound represented by the following formula (1) as an extractant for removing colored foreign substances such as pigments or dyes from a monomer of a polymer resin containing an ester functional group . In the compound represented by Formula 1, at least one alkyl group is connected to the aromatic ring through a linker, and the linker has at least one oxygen.

[화학식 1]

[Formula 1]

In Formula 1, 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 an 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 is an integer, and when m is 2 or more, -OR ₂ is the same or different.

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-dimethoxy Acetophenone, 3-(4-hydroxy-3,5-dimethoxyphenylprop-2-enoic acid, 4-enyl-2,6-dimethoxyphenol, 4-hydroxy-3-methoxybenzalde Hyde, 3-hydroxy-4-methoxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-4-methoxy Benzaldehyde, 3,4-dihydroxybenzaldehyde, 1-methoxy-4-[(E)-prop-1-enyl]benzene, 1-bromo-4-methoxybenzene, 2-tert -Butyl-4-methoxyphenol, ethoxybenzene, phenol, 1,3,5-trichloro-2-methoxybenzene, 1,3,5-tribromo-2-methoxybenzene, 4- (pro P-2-en-1-yl)phenol, 1-methoxy-4 (prop-2-en-1-yl)benzene, 5-(prop-2-en-1-yl)-2H-1 Obtained from nature, such as ,3-benzodioxole, 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 synthetic or synthetic compounds.

In addition, in one embodiment of the present invention, the monomer of the polymer resin including the ester functional group may be obtained from a depolymerization reaction of the polymer resin including the ester functional group. In particular, the polymer resin including the ester functional group is It may be a colored polymer resin, and when the compound represented by Formula 1 is added to the depolymerization reaction, it does not directly participate as a reactant in the depolymerization of a polymer containing an ester functional group, but maintains the performance related to the depolymerization reactivity and product selectivity even at a low temperature reaction. It can be used in the form of performing depolymerization after being mixed with the polymer resin before depolymerization.

The extractant according to the present invention is useful as an extractant for removing foreign substances such as pigments and dyes from a monomer of a polymer resin containing an ester functional group, wherein the polymer containing an ester functional group is used alone or in the form of a mixed waste plastic For example, polyethylene, high-density polyethylene, low-density polyethylene, polypropylene, or a combination thereof may be in a mixed form with the polymer including the ester functional group. Other polymers to be mixed with the polymer containing the ester functional group listed as examples above are merely examples and are not limited to those listed above.

In addition, the present invention provides a purification method for producing a high-purity monomer by removing foreign substances from a monomer of a polymer resin containing an ester functional group.

The purification method includes the steps of 1) adding and mixing the compound represented by Formula 1 to a monomer of a polymer resin including an ester functional group containing a colored foreign substance; 2) inducing liquid-liquid phase separation by standing still the mixed solution in step 1); 3) separating the phase-separated liquid-liquid layer into an upper organic solution layer and a lower aqueous solution layer;

Step 1) is a step of adding an extractant for extracting foreign substances from the monomer of the polymer resin including an ester functional group, and mixing it to distribute more foreign substances to the extractant.

The extraction and distribution temperature in step 1) can be performed after inducing phase separation without adding a hydrophilic solvent in a region lower than or at the depolymerization reaction temperature of a polymer containing a general ester functional group, but the extraction process can be carried out as shown in Formula 1 If an excessive amount of water, which has a very limited solubility, is added, the phase separation boundary occurs more clearly, and it induces an extremely asymmetric distribution of the depolymerized product and foreign substances, so that the monomer can be recovered in high purity.

Since the compound represented by the formula (1) is a material having a relatively high affinity for organic substances that express color, such as dyes or pigments, foreign substances that express color such as dyes or pigments in step 1) are represented by the formula (1) Most of the compounds are transferred to the organic phase, and other hydrophobic compounds and monomeric products are mostly capable of mass transfer into the hydrophilic phase.

The temperature range during extraction and distribution in step 1) may occur in the range of 25 ~ 150 ℃.

The removal of foreign substances such as dyes or pigments and the purification of monomers, which are carried out according to the liquid-liquid extraction according to the present invention, may be most economical to use water, but additives and hydrophilic substances that can induce a thermodynamically unstable phase may be used. This can be carried out even in the presence of a polyhydric alcohol used as a reactant without the addition of a separate solvent.

Step 2) is a step of allowing the liquid-liquid phase separation of the mixed solution after the asymmetric distribution of foreign substances or the like occurs by mixing.

Induction of the liquid-liquid phase separation can be performed continuously or batchwise using a known means such as a decanter, and a composition and a temperature that cause the phase separation to occur because the thermodynamic miscibility is sufficiently low with each other may be used. Since the composition and temperature for causing the phase separation to occur can be easily selected by a person skilled in the art, detailed description thereof will be omitted.

As an example, in FIG. 1, on the solubility curve for each temperature determined to distinguish the thermodynamic phase equilibrium state of the binary compound composed of anisole, which is one of the extractants according to the present invention, and a hydrophilic solvent (water or ethylene glycol), the present invention Reaction conditions for depolymerization performed according to an example of , and purification conditions for extraction are schematically shown. Here, the x-axis represents the composition of the organic extractant anisole in mole fraction, and the y-axis represents the reaction or purification temperature. An appropriate composition and temperature for phase separation may be selected with reference to the diagram in FIG. 1 .

Step 3) is a step of separating and discharging the organic phase (organic solution layer) and the aqueous phase (aqueous solution layer) in the phase-separated liquid-liquid layer, respectively. Separation is carried out using conventional means, and the organic phase and aqueous phase after separation are individually post-treated to further increase the recovery rate of the desired product.

In another embodiment of the purification method of the present invention, a hydrophilic solvent such as water is added to the organic solution layer (or organic phase) in which the compound represented by Formula 1 primarily separated in step 3) constitutes the majority. to redistribute a small amount of the monomer remaining in the organic phase, and may further include the step of performing back extraction and additionally recovering the monomer product therefrom.

In addition, methods such as distillation using gas-liquid separation to separate dyes and pigments while recovering the additive represented by Formula 1 from the organic phase separated and discharged by the liquid-liquid extraction according to the present invention are included. can

The monomer product concentrated in the separated and discharged aqueous solution layer can be recovered most of the product through crystallization, and trace amounts of additives that may remain in the purified target product are dried by heating at 50~150°C, preferably heated under vacuum. It can also be easily and completely removed by drying.

The monomer purification process of the polymer resin including the ester functional group according to the present invention may be performed in parallel or by adding a process of physically filtering and separating and removing some foreign substances.

In one embodiment of the present invention, the monomer of the polymer resin containing the ester functional group in step 1) may be a depolymerization reaction mixture obtained by depolymerizing the polymer resin containing the ester functional group or a derivative obtained therefrom. These depolymerization reaction mixtures may be in a state that has not undergone purification or the like after the reaction, or may have been partially purified.

As described above, when the monomer of the polymer resin containing the ester functional group in step 1) in the present invention is a depolymerization reaction mixture obtained by depolymerizing the polymer resin containing the ester functional group or a derivative compound obtained therefrom, the extractant is The addition may be carried out at a stage before or after the depolymerization process.

Polymer resins containing ester functional groups can be decomposed into low molecular weight compounds such as monomers, dimers, and oligomers through depolymerization, and as possible depolymerization pathways, hydrolysis, glycolysis, methanolysis There may be methanolysis, ammonolysis, and the like, and a complex process combining them may be used.

Specifically, the method of adding the extractant to the step prior to the depolymerization process to remove foreign substances that express color in the depolymerization reaction mixture, and purifying the monomer obtained from the depolymerization of a colored polymer resin containing an ester functional group with high purity, a ) adding the compound of Formula 1 to a colored polymer resin containing an ester functional group; b) depolymerizing the polymer resin including the ester functional group; c) adding and mixing water or a hydrophilic solution immiscible with the compound represented by Formula 1 to the depolymerization reaction mixture obtained from the depolymerization reaction; d) inducing liquid-liquid phase separation by standing still the mixed solution in step c); e) separating and discharging the phase-separated liquid-liquid layer into an upper organic solution layer and a lower aqueous solution layer.

The purification process of the depolymerized monomer of the colored polymer resin including the ester functional group according to the present invention may be performed in parallel or by adding the process of physically filtering unreacted polymer material or some foreign material from the depolymerization reaction mixture to separate and remove it.

The depolymerization of the polymer containing an ester functional group according to the present invention may be performed in the presence or without a catalyst by addition of alcohol, water, or hydroxide and by following an exchange esterification reaction route.

Hereinafter, 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 to be understood that this alone cannot limit the scope of application of the present invention.

Raw material 1 (waste PET film containing pigment)

Only colored labels whose constituent polymers are PET were recovered from the waste plastic containers discharged after consumption, classified by main constituent colors, and cut to a size of 0.5 mm or less on one side to prepare raw material 1.

Raw material 2 (polyester fiber with dye)

The polyester fabric dyed using anthraquinone-based disperse dye was cut to have an area of 1 cm ² or less to prepare a fiber raw material.

Experimental Example 1: Depolymerization reaction step (when no additives are added before reaction)

About 10 g of a polymer raw material containing an ester functional group and about 38.8 g of ethylene glycol, a dihydric alcohol polar solvent, were put into a 3-neck flask, a reflux condenser was installed at atmospheric pressure, and stirring was started using a magnetic stirrer. When the reaction mixture reached 197° C. or reflux temperature, about 0.46 g of a zinc acetate catalyst was added to initiate a catalytic reaction, and the reaction temperature was kept constant within ±1° C. while stirring continuously for 2 hours. The reaction was carried out using a condenser exposed to . At the time when the reaction was completed, a trace amount of the reaction mixture was taken and prepared as a sample for quantification. Reaction yields for depolymerized monomers and dimers were measured using high-performance liquid chromatography (HPLC with C18 column, UV detector (μ=254 nm)) calibrated with each standard sample. As a mobile phase for HPLC analysis, a mixed solution of 70:30 by volume of methanol:water was used, and the total flow rate was maintained at 0.7 ml/min. The remaining majority solutions of the reaction mixture were filtered using cellulose acetate filter paper (pore size: 0.45 μm). After separation, the unreacted polymer remaining on the filter paper was completely dried and quantified.

Experimental Example 2: Depolymerization reaction step (when additives are added before reaction)

Before the start of the depolymerization reaction, about 22.5 g of anisole (methoxybenzene) was put into a 3-neck flask along with the colored polymer raw material and ethylene glycol, and when the reaction mixture reached 153°C or reflux temperature, about 0.20 g of potassium acetate catalyst was added. The same method as in Experimental Example 1 was applied except that the catalytic reaction was started.

Experimental Example 3: Liquid-liquid extraction step

After completion of the reaction, about 200 g of distilled water at 95 to 100° C. was added to the filtrate obtained from filtration. After that, stirring was carried out by moving to a container maintained at 75° C., and after stopping stirring after 1 hour, when phase separation occurred, the lower aqueous layer was taken, and the temperature was lowered by leaving it at room temperature.

Experimental Example 4: Liquid-liquid back extraction step

After adding about 200 g of distilled water of 95 to 100 ° C to the organic layer separated in the liquid-liquid extraction step as in Experimental Example 3, it was moved to a container maintained at 75 ° C. The lower aqueous layer was taken, and the temperature was lowered by leaving it at room temperature.

Experimental Example 5: Depolymerization commercialization step

After leaving the reaction mixture solution containing the monomer or the aqueous phase extracted in Experimental Example 3 or Experimental Example 4 for 12 hours in a storage where the temperature is maintained at 4°C, the crystallized solid phase is subjected to physical filtration using a physical filtration method. After removal, it was taken as a solid. This was again transferred to a vacuum dryer in which the temperature was maintained at 60° C. and vacuum dried for more than 12 hours to obtain a depolymerized product.

Experimental Example 6: Organic solvent and dye recovery step

In Experimental Example 3 or Experimental Example 4, the upper phase (organic layer) remaining after the aqueous layer was separated was separated and condensed in a liquid phase by separating and condensing anisole into a vapor phase using a single distiller. It could be obtained as a semi-solid product. Each of the obtained products was quantified using a high-precision balance with an accuracy of ±0.1 mg.

Comparative Example 1:

Raw material 1 was subjected to depolymerization according to Experimental Example 1, and a monomer product was obtained according to the method of Experimental Example 5.

Comparative Example 2:

Raw material 1 was subjected to depolymerization according to Experimental Example 2, and a monomer product was obtained according to the method of Experimental Example 5.

Example 1:

Raw material 1 was depolymerized according to Experimental Example 2, and after liquid-liquid extraction of Experimental Example 3 was performed, an aqueous phase was taken to obtain a monomer product according to the method of Experimental Example 5.

Example 2:

The same procedure as in Example 1 was performed except that about 22.5 g of anisole was additionally added to the aqueous solution layer in which the organic layer was separated from the reaction mixture through the liquid-liquid extraction process according to the method of Experimental Example 3, and then the solution of Experimental Example 3 - The liquid extraction step was repeated once more, and an aqueous phase was taken to obtain a monomer according to the method of Experimental Example 5.

Example 3:

About 22.5 g of anisole and about 200 g of distilled water at 95 to 100° C. were added to the depolymerized product obtained in Comparative Example 1, liquid-liquid extraction of Experimental Example 3 was performed, and the aqueous phase was taken to prepare a monomer product according to the method of Experimental Example 5. obtained.

Example 4:

Using the organic layer separated in the liquid-liquid extraction process of Experimental Example 3 obtained according to the method of Example 2 as a raw material, the liquid-liquid reverse extraction step of Experimental Example 4 was performed, and then the aqueous phase was taken to the method of Experimental Example 5. Thus, a monomer product was obtained.

Comparative Example 3:

A monomer product was obtained in the same manner as in Comparative Example 2, except that Raw Material 2 was used.

Example 5:

A monomer product was obtained in the same manner as in Example 2, except that Raw Material 2 was used.

Example 6:

After performing the liquid-liquid reverse extraction step of Experimental Example 4 using the organic layer separated in the repeating process of liquid-liquid extraction obtained according to the method of Example 5 as a raw material, the aqueous phase was taken and the monomer according to the method of Experimental Example 5 The product was obtained.

Example 7:

It was carried out in the same manner as in Example 5 (using raw material 2), but about 22.5 g of anisole was additionally added to the aqueous solution layer in which the organic layer was separated from the reaction mixture through the liquid-liquid extraction process according to the method of Experimental Example 3 After the liquid-liquid extraction of Experimental Example 3 was repeated a total of 4 times, an aqueous phase was taken to obtain a monomer product according to the method of Experimental Example 5.

[Preparation of high-purity monomer from waste PET film containing pigment]

The structural characteristics of the purified monomer were confirmed using nuclear magnetic resonance (model name: Bruker Avance II 500 MHz). The residual amount of organic foreign matter was estimated. Samples in which 20 mg of purified monomer and 10 mg of organic foreign matter were diluted in 0.7 ml of DMSO- d ₆ solvent were used for measurement.

A bis(2-hydroxyethyl) terephthalate (BHET) monomer obtained from a glycolysis reaction using a polymer containing an ester functional group as a raw material and a concentrated pigment recovered from a colored PET film (prepared according to Experimental Example 6) ), the NMR spectrum is shown in FIG. 2 . The depolymerized products prepared through the process of Examples 2 to 4 corresponded to BHET monomers purified to ^a high purity of 99.9% or more. was observed to be very similar to

¹ H-NMR (500 MHz, DMSO- d ₆ ) δ (ppm): 8.13 ( s , 4H), 4.96 ( t , 2H), 4.32 ( t , 4H), 3.72 ( q , 4H)

As reported, a characteristic peak attributable to hydrogen contained in the hydroxyl group, which is the terminal group, near 4.96 ppm is observed as a triplet due to the interaction of adjacent ethylene groups with hydrogen, and near 3.72 ppm, the hydrogen Quartet-shaped peaks characterized by hydrogen directly bonded to the ethylene functional group adjacent to the hydroxyl group (corresponding to 3 and 4 of the BHET formula shown in FIG. 1) were observed without distortion.

The NMR spectrum (upper spectrum in Fig. 1) of organic foreign matter containing pigment extracted from colored PET film is very complex, and when only normal physical filtration is applied to purify polymer depolymerization products, some organic matter can be removed, but colored organic matter It can be seen that the mixture is not easy to remove. In particular, organic compounds with chemical shift values of 0.94 and 4.69 ppm had color development properties similar to those of the colored PET film as the starting material, even though only trace amounts were included. High-purity purification of the depolymerized monomer product (BHET) was possible.

The foreign material content was calculated by comparing the mass values of the samples (organic foreign matter and purified BHET) used in the NMR spectrum with the integral values of the characteristic peaks, and the estimated foreign material content based on the chemical shift value is shown in Table 1 (colored lungs). Characteristics of monomer products subjected to PET depolymerization and purification).

The yield of the depolymerized product was calculated as the ratio (%) of the number of moles to the amount of product quantified by HPLC for the depolymerized product obtained from each process, with the total number of moles of repeating units in the polymer input as the initial raw material being 100. The amount of depolymerized monomer products recovered according to Comparative Example 1 and Examples 1 to 4 using a waste PET film containing a pigment and having a color as a raw material is listed in Table 1 as BHET molar yield (%). As the extraction process was repeated two or more times, the content of foreign substances was observed to be very low, but as the mass of the monomer lost during the purification process of the product increased, the yield of the final product decreased.

division Raw material depolymerization
catalyst ^a refine
Way product
colour BHET
forfeiture
(%) ^b Foreign matter (wt.%) ^c peak 1
(0.94ppm) Peak 2
(4.69ppm) Comparative Example 1 PET film
(yellow) Zn(OAc) ₂ percolation dark yellow 80.3 0.7 1.9 Comparative Example 2 PET film
(green) K(OAc) percolation dark green 79.2 2.1 0.4 Example 1 PET film
(green) K(OAc) percolation,
extraction pale green
pale white 76.8 0.3 0.2 Example 2 PET film
(green) K(OAc) percolation,
2 extractions White 74.3 - - Example 3 low purity BHET
(yellow) K(OAc) percolation,
extraction White 75.4 - - Example 4 organic phase reaction mixture (green) K(OAc) back extraction White 1.7 - - a. Zn(OAc) ₂ : Zinc acetate, KOAc : Potassium acetate
b. Yield (%) converted to the number of moles of the obtained BHET product compared to the number of moles of the starting PET repeating unit
c. ¹ H-NMR characteristic peak (δ = 0.94, 4.69 ppm) Concentration of foreign substances converted from the integral value

[Production of high-purity monomers from polyester fibers containing dyes]

Unlike pigments, which are dispersed in a solvent and then colored in the form of particles or powder, dyes used in a dissolved state are mainly used for dyeing textile materials or leather. In particular, in order to color a fiber material such as a polymer fiber containing an ester functional group, for example polyester, a dye in the form of an organic compound containing at least one aromatic ring is generally used for coloring.

As the dye, a material having a very high affinity with the terephthalate functional group constituting the fiber is used as a dye in order to prevent discoloration from the polymer fiber, and it should have a property to be uniformly dispersed in the fiber physically and chemically, Due to this, even if depolymerization proceeds, it may not be easy to separate and purify a high-purity product due to high interaction with monomers or low-molecular compounds produced by depolymerization. Therefore, although some miscibility with the product monomer or low-molecular compound exists, a large number of solvents with strong affinity with organic dyes are supplied, and when an excess of hydrophilic solvent is added to this, asymmetrical solute (dye) distribution can be induced. and recovery of high-purity products is possible.

3 shows the NMR spectrum of the BHET monomer obtained from the reaction and the dye recovered and concentrated according to Experimental Example 6 after depolymerization was performed using the colored polyester fiber as a raw material.

¹ H NMR spectra obtained by using a part of the product prepared according to the method of Examples 5 to 7 as a sample are the same as the spectra obtained from Examples 1 to 4 in which a raw material including a pigment is applied, the main peaks are BHET It was clearly observed in the intrinsic chemical shift values indicative of the monomer structural properties. However, if the extraction recovery is limited or the product is additionally recovered through back extraction, the overall yield of the depolymerized product can be increased, while the purity of the BHET monomer is limited to less than 99%, and the inherent color of the dye contains foreign substances. It can be seen that the removal does not proceed effectively. As a result of observing the monomer products manufactured according to the specific experimental examples of the present invention, it was possible to easily determine with the naked eye that the organic dye contained a pigment foreign material even if only a trace amount of 1% or less by mass remained.

In order to recover BHET of the same quality as the high-purity monomer product (Example 2 to Example 4) obtained by purifying the reactant obtained from the depolymerization of the waste PET material containing the pigment mentioned above, a number of the same as described in Example 7 It can be seen that an iterative extraction process of

Table 2 is specific examples showing processes for obtaining a high-purity monomer from a depolymerization reaction mixture obtained using a colored polyester raw material. It was found that when the extraction and purification process (Experimental Example 3) was applied by adding the compound represented by Formula 1, the organic disperse dye constituting the color could be efficiently removed. The product obtained from the case where the extraction and purification process was repeated two or more times (Example 5) and the case where the reverse extraction was performed using the organic phase generated in the second extraction process (Example 6) had a purity of 99.5% or more, A powder with a pale red color was obtained as a product due to a trace amount of residual dye. When the extraction and purification process was repeated 4 or more times, the yield of the final product was very low, about 51%, but the residual amount of dye was detected at a level of 0.1% or less, and a high-purity white BHET product was obtained.

division Raw material depolymerization
catalyst ^a refine
Way product
colour BHET
transference number
(%) ^b Foreign matter (wt.%) ^c peak 1
(3.56ppm) Peak 2
(4.52ppm) peak 3
(8.06ppm) Comparative Example 3 polyester fiber
(dark blue) K(OAc) percolation thick
Red 75.2 > 5.0 > 6.2 > 4.7 Example 5 polyester fiber
(dark blue) K(OAc) percolation,
2 extractions pale
Red 68.2 0.37 0.24 0.16 Example 6 organic phase reaction mixture
(Black color) K(OAc) back extraction pale
Red 4.3 0.39 0.26 0.17 Example 7 polyester fiber
(dark blue) K(OAc) percolation,
4 extractions White 51.3 - - - a. Zn(OAc) ₂ : Zinc acetate, KOAc : Potassium acetate
b. Yield (%) converted to the number of moles of the obtained BHET product compared to the number of moles of the starting PET repeating unit
c. ¹ H-NMR characteristic peak (δ = 3.56, 4.52, 8.06 ppm) Concentration of foreign substances converted from the integral value

As described above in detail a specific part of the content of the present invention, for those of ordinary skill in the art, this specific description is only a preferred embodiment, and it will be clear that the scope of the present invention is not limited thereby. . Accordingly, it is intended that the substantial scope of the invention be defined by the appended claims and their equivalents.

Claims (11)

As an extractant for removing foreign substances expressing color from a monomer of a polymer resin containing an ester functional group,
The extractant is an extractant for removing a foreign substance expressing a color from a monomer of a polymer resin comprising an ester functional group, characterized in that it comprises a compound represented by the following formula (1).

[Formula 1]
(In Formula 1,
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 the same or different,
R ₂ is a C ₁ -C ₁₀ alkyl group,
Wherein m is an integer of any one of 1 to 6, and when m is 2 or more, -OR ₂ is the same or different.)
According to claim 1,
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-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-hydro Roxy-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, 3,4-di Hydroxybenzaldehyde, 1-methoxy-4-[(E)-prop-1-enyl]benzene, 1-bromo-4-methoxybenzene, 2-tert-butyl-4-methoxyphenol, Ethoxybenzene, phenol, 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- Ester, characterized in that at least one selected from the group consisting of methoxy-2-[(E)-prop-1-yl]phenol and 2-methoxy-4-(prop-1-en-yl)phenol An extractant for removing a foreign substance that expresses color from a monomer of a polymer resin containing a functional group.
According to claim 1,
The monomer of the polymer resin containing the ester functional group, characterized in that obtained from depolymerization of the polymer resin containing the ester functional group,
An extractant for removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.
In the purification method for producing a high-purity monomer by removing foreign substances from a monomer of a polymer resin containing an ester functional group,
1) adding and mixing a compound represented by the following formula (1) to a monomer of a polymer resin including an ester functional group containing a color-expressing foreign substance;
2) inducing liquid-liquid phase separation by standing still the mixed solution in step 1);
3) separating and discharging the phase-separated liquid-liquid layer into an upper organic solution layer and a lower aqueous solution layer;
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.

[Formula 1]
(In Formula 1,
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 the same or different,
R ₂ is a C ₁ -C ₁₀ alkyl group,
Wherein m is an integer of any one of 1 to 6, and when m is 2 or more, -OR ₂ is the same or different.)
5. The method of claim 4
In the step 1), in addition to the compound represented by Formula 1, water or a hydrophilic liquid immiscible with the compound represented by Formula 1 is added to the monomer containing the foreign material that expresses the color,
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.
5. The method of claim 4,
The monomer is a mixture after depolymerization obtained by depolymerizing a polymer resin containing an ester functional group, or a mixture obtained by partially purifying the mixture after the depolymerization reaction,
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.
5. The method of claim 4,
The step of further adding a compound represented by Formula 1 to the separated aqueous solution layer to further extract foreign substances that express color; characterized in that the repeated one or more times,
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.
5. The method of claim 4,
to the separated organic solution layer, further adding water or a hydrophilic liquid immiscible with the compound represented by Formula 1, mixing the mixture, and performing phase separation again; characterized in that it further comprises,
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.
5. The method of claim 4,
recovering a monomer of a polymer resin including an ester functional group through recrystallization from the separated aqueous phase; characterized in that it further comprises,
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer of a polymer resin containing an ester functional group.
a) adding a compound of Formula 1 to a colored polymer resin containing an ester functional group;
b) depolymerizing the polymer resin including the ester functional group;
c) adding and mixing water or a hydrophilic solution immiscible with the compound represented by Formula 1 to the depolymerization reaction mixture obtained from the depolymerization reaction;
d) inducing liquid-liquid phase separation by standing still the mixed solution in step c);
e) separating and discharging the phase-separated liquid-liquid layer into an upper organic solution layer and a lower aqueous solution layer;
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer obtained by depolymerization of a colored polymer resin containing an ester functional group.

[Formula 1]
(In Formula 1,
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 an 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,
Wherein m is an integer of any one of 1 to 6, and when m is 2 or more, -OR ₂ is the same or different.)
11. The method of claim 10
Characterized in that the organic solvent is recovered through distillation from the organic solution layer separated and discharged in step e) and recycled.
A purification method for producing a high-purity monomer by removing foreign substances that express color from a monomer obtained by depolymerization of a colored polymer resin containing an ester functional group.

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