Method for producing terephthalate derivative by depolymerization of polymer containing ester functional groups

Abstract

To provide an efficient method for recycling waste PET raw materials by depolymerizing and repolymerizing them.SOLUTION: In a preferred embodiment, waste PET raw material is decomposed by passing nitrogen or the like at a gas hourly space velocity in the presence of a polar aprotic solvent such as methanol and potassium carbonate (K2CO3) to obtain DMT (dimethyl terephthalate). Furthermore, potassium carbonate (K2CO3) and the like are used to manufacture (bis-(2-hydroxyethyl) terephthalate, BHET) and the like.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to dimethyl terephthalate, DMT) through an ester exchange reaction, the functional group attached to the terephthalate is converted to another form. and the transesterification reaction to produce a highly modified derivative containing an ester functional group. The present invention relates to an efficient method for depolymerizing a polymer comprising the steps of: In the transesterification reaction using alkali metal carbonate, alkali hydroxide, and arsenic as raw materials, Potassium metal alkoxides, alkaline earth metal oxides and guanidine At least one selected from the above organic compounds is used as a catalyst at room temperature (25°C) or By carrying out the transesterification reaction at a temperature below the boiling point of the optimally applied alcohol, high loading An efficient conversion method capable of producing terephthalate derivatives in high yields, and In combination with the methanolysis reaction, the highly-added terephthalate derivative can be obtained in high yields and the ethylenediamine can be obtained. The process efficiency and economics of the ester exchange reaction can be improved by using an ester functional group. This relates to a polymer depolymerization reaction process. [Background technology]

[0002] Plastics have the advantages of being cheap, durable, and easy to mold and process. It has many advantages and is used in the production of various products. The consumption of coal has increased dramatically in various sectors of industry and daily life for several decades, but due to poor management, Plastic waste is left in the environment, causing environmental pollution, or is broken down into small pieces. Microplastics float around the ecosystem and accumulate in living organisms, resulting in fine dust particles. However, there are problems with it re-entering the human body through drinking water, food, etc. More than 50% of this plastic is used in packaging, agricultural films, disposable consumer goods, etc. How it will be used for single-use disposable purposes or disposed of within one year of manufacture It is used as a short-term product.

[0003] Most discarded plastic ends up in designated landfills or natural habitats where natural purification is difficult. The problem of environmental pollution is becoming more and more serious. Degradable plastics also vary depending on local environmental factors such as the level of UV exposure, temperature, and the presence of decomposing microorganisms. It may persist for decades depending on environmental factors.

[0004] In order to solve this problem, we have developed a new plastic material that has a short decomposition cycle in nature. In addition to developing new materials, we are also working to develop new methods for the physical regeneration of plastics, starting with the chemical decomposition of existing petroleum-based plastics. Minimize the accumulation of plastics and reduce their environmental impact from recycling to recycling and reprocessing. Various research is being conducted to achieve this.

[0005] Polymers containing ester functional groups can be depolymerized to form Monomerization is possible through the use of various chemical reaction pathways. Theoretically, the monomers that are synthesized should have the same properties as the raw materials that are used in the initial polymer synthesis. The depolymerization pathways that have been applied industrially to recycle polyester are These include hydrolysis, glycolysis, and metabolite synthesis. Methanolysis, Ammonolysis These can be combined to create a composite process that utilizes the advantages of each process. Chemical depolymerization methods are widely used.

[0006] The above-listed methods for producing polymers containing ester functional groups by depolymerization are described in more detail below. Specifically, in the case of hydrolysis, various reaction pathways occur in the presence of acid, base, or metal salt catalysts. It is known that decomposition can occur by using acid as a catalyst. Since a high concentration of sulfuric acid solution is always required to obtain a high conversion rate, the design, operation and post-treatment of the process The disadvantages of the reaction using bases and metal salt catalysts include the economical problems associated with the use of bases and metal salt catalysts. In this reaction system, the decomposition reaction rate is very slow, the product purity is low, and catalyst recovery is difficult, making it inefficient. This is true.

[0007] Glycolysis is a depolymerization reaction that adds glycol as a reactant. The most common example of this is the excessive addition of ethylene glycol, one of the monomer raw materials. Bis(2-hydroxyethyl) terephthalate There is a process for manufacturing polyethylene terephthalate (BHET). The reactant is ethylene glycol, which is one of the raw materials for the synthesis of PET polymers. The product produced by the depolymerization reaction has ethyl terephthalate at both ends for use as a It has a chemical structure in which ethylene glycol is already bonded. Even if only a portion of the raw materials used in the polycondensation process using tartaric acid is substituted, it is very effective in terms of reaction dynamics. can produce beneficial results.

[0008] In addition, the product obtained by the glycolysis reaction can be used directly as a raw material for the synthesis of PET. This allows you to modify only a part of your existing PET production line without making any additional capital investments. The advantage of glycolysis is that it can be applied to the production of polymeric materials. This is generally carried out under reflux conditions of glycol, and is the stage where oligomers are decomposed into monomers. The reaction rate is slow, and even if the reaction time is delayed, the equilibrium state between the compounds is reached, resulting in low product purity. and the final product, the monomer, can be separated from the reactants in high purity or high yield. Generally, metals such as zinc acetate or lithium acetate are used. Salts are used as reaction catalysts. The metal ions that make up such catalysts are completely purified during the purification process. There is a risk that metals that are harmful to the human body even in small amounts may not be completely removed and may remain in the product. Products that may contain monomers and are produced by re-injecting them, especially food and medical products There are some aspects of recycling of materials for daily necessities and other daily necessities that are difficult to utilize. The reaction is carried out at high temperatures, but the product recovery and purification process is carried out by a low-temperature recrystallization method. This generally requires a large amount of energy and the cost of the heat source supply method for the production process is high. There is a problem with this, which is that it is less efficient.

[0009] The methanolysis process has been used not only by global chemical companies in the past, but also by small and medium-sized plastics companies. This is one of the processes that has been widely applied in actual commercial processes. Dimethyl terephthalate (DMT) is the most The final monomer product is decomposed into terephthalic acid as the transesterification reaction proceeds. In the actual reaction, the molar equivalent of ethylene glycol is released. Side reactions such as partial methanolysis, reaction equilibrium with free ethylene glycol, and hydrolysis Hydroxyethyl methyl terephthalate (1-(2-HYdroxyethyl )4-methyl terehthalate, HEMT) Monomethyl terephthalate (MMT) and other compounds were found in the reaction products. The target compound of the methanolysis reaction, DMT, can be produced as a by-product by reacting with other monomers with higher addition properties. or a combined hybrid depolymerization process (e.g., methanolysis-glycolysis) for the production of It can be used as an intermediate raw material for the production of ethylene glycol. In addition, it has a relatively low boiling point compared to other monomers. It is easy to control the selectivity for the hydrogenation reaction, and it is possible to produce a highly-added diol monomer (e.g., It can be used as a gas phase reactant for the production of 1,4-cyclohexanedimethanol and can be recrystallized. It is easy to purify by polymerization or distillation, and high purity and high quality are required for PET polymerization. It can also be used as a raw material. However, because methanol is used as a reaction solvent, high temperatures and high pressures are required. The reactor and the durable components required for this operation are The initial cost may be excessive because of the need to provide related facilities that have the properties of reactants. Additional unit processes for recovery and product purification are required, which may require high capital costs. The catalyst used is a depolymerization catalyst commonly used in glycolysis reactions. It contained heavy metals such as zinc acetate, magnesium acetate, cobalt acetate, and lead dioxide. A typical example is a transesterification catalyst, but there is a risk of human toxicity due to residual metals in the product. There is a risk that this could lead to sexual and environmental problems.

[0010] The depolymerization reaction process of polymers containing ester functional groups is carried out in conjunction with a hydrolysis or alkaline decomposition process. Methanolysis was widely used in the synthesis of olefins, but both reactions were high-temperature, energy-intensive processes. Therefore, carrying out the depolymerization at low temperatures can result in long reaction times, limiting the quality and quantity of the products produced. When methanolysis is selected as the reaction route for the production of depolymerized monomer, the monomer product The yield and purity of a given DMT are greatly affected by the reactivity of the catalyst and reaction impurities. In order to reduce the burden on the purification process of the product, it is necessary to have an effective method to suppress side reactions and high reactivity at the same time. is required.

[0011] As a prior art, Japanese Patent Laid-Open No. 1998-287741 (Patent Document 1) describes a method for recycling waste PET. Dimethyl terephthalate and alkylene glycol were obtained by treating with methanol, respectively. A method for recovering terephthalic acid from a polyalkylene terephthalate polymer with high efficiency. When recovering dimethyl, methanol is added to the polymer, which is at least partially in a molten state. The polyalkylene terephthalate was depolymerized to produce DMT while continuously introducing In this synthesis, potassium carbonate is used as a catalyst at a depolymerization reaction temperature of 200 to 300°C. In the above patent, the depolymerization temperature is too high, which causes problems with the equipment. The disadvantages are the excessive investment costs and the energy used in the reaction process.

[0012] Therefore, to depolymerize polymers containing ester functional groups by methanolysis, This allows the depolymerization reaction rate to be increased without using excessive energy, and the reaction selection A method for producing DMT in high yields with improved solubility would be advantageous, and this method can be used as an intermediate. If a continuous transesterification reaction can be achieved using the same catalyst, the energy consumption will be reduced. To produce BHET or other forms of terephthalate derivatives in high yields while It is expected that an efficient and economical process can be realized.

[0013] As an example of the above reaction, DMT and ethylene glycol were used as starting materials to produce a high-additive monosaccharide. In the transesterification reaction in which the final product is the monomer BHET, A HEMT with partially substituted methyl end groups is generated as a reaction intermediate and hydrolyzed. As a by-product, a compound in which a carboxylic acid functional group is bonded to terephthalate is produced. By suppressing such side reaction pathways to the maximum extent possible, two molar equivalents of methylmercaptoethanol bound to DMT can be produced. The ester exchange reaction was carried out in stages so that all the ethanol could be replaced by ethylene glycol. The design of a reaction pathway that can promote the reaction and the optimal route where BHET production can be predominantly carried out are By clarifying the optimal operating conditions and applying them to the process, an efficient BHET manufacturing process can be established. It is expected that this will be possible.

[0014] Non-patent literature: "Zn- and Ti-Modified Hydrotalcites for Transesterification of Dimet hyl Terephthalate with Ethylene Glycol: Effect of the Metal Oxide and Catalyst S ynthesis Method” (Amarsinh L. Jadhav, Radhika S. Malkar, and Ganapati D. Ya, AC S Omega 2020, 5, 2088-2096) was transesterified with DMT and ethylene glycol. In carrying out the reaction, zinc and titanium are converted into hydrotalcites. After the introduction, the composite metal planar structure produced by reforming is used as a catalyst to produce high-addition-value single-unit fuel. There have been reports of an example in which the selectivity of the dimer BHET could be improved to 96.1%. do.

[0015] However, in the case of the above-mentioned prior art, although the transesterification reaction was carried out at a high temperature of 180°C, The conversion rate of dimethyl terephthalate was less than 70%, and the reaction The purification of BHET from the mixture can consume a lot of energy, and the catalyst production process The process is complex and may be difficult to reproduce, and metals incorporated in the catalyst may also be leached out. These problems may limit the efficiency and economic viability of the process for commercial application.

[0016] Therefore, the transesterification of DMT to produce highly-added terephthalate derivatives is In this regard, excessive energy is not used and less harmful environmentally friendly materials are used. In both cases, it is important to ensure economic efficiency by using low-cost catalysts and simplifying the process. The process enables not only high DMT conversion but also high yields of terephthalate derivatives. There is a need to develop integrated reaction and purification process technologies that improve both process efficiency and economy. The resulting derivatives are used as recycled monomers for recycling waste plastic resources, as additives for plasticizers, etc. , polymerization raw material for synthesizing materials in which glycols are partially or completely modified to improve physical properties, It can be used as a diverse upcycling raw material with high industrial value. Summary of the Invention [Problem to be solved by the invention]

[0017] In order to solve the above problems, the present invention provides a method for producing a high-addition single crystal with a high yield while simplifying the process. A transesterification method capable of producing dimethyl terephthalate (D The present invention seeks to provide a method for producing other forms of terephthalate derivatives from terephthalic acid (MT).

[0018] The present invention also extends the method for converting DMT to other forms of terephthalate derivatives. In this study, we applied the reaction products generated from the depolymerization of polymers containing ester functional groups to the monovalent and By using polyhydric alcohol and / or polyhydric alcohol as reactants, the reaction can be carried out at room temperature (25°C) or The terephthalate derivative is produced as a product in high yield at a temperature below the boiling point of the alcohol. The present invention relates to a method for producing multiple esters by using a polymeric starting material containing an ester functional group as a starting material. An efficient and efficient method for producing highly-added terephthalate derivatives by ester exchange reaction The present invention provides an economical method for depolymerization. [Means for solving the problem]

[0019] In order to solve the above problems, the present invention provides a method for the preparation of a monovalent and / or polyvalent dimethyl terephthalate. In the method, polyhydric alcohol is added as a solvent for transesterification, and alkali carbonate, alkali Hydroxides, alkali alkoxides, alkaline earth metal oxides and guanidine-based organic compounds In the presence of at least one transesterification catalyst selected from the group consisting of (b) carrying out a transesterification reaction while adding a flow of agarose; and and separating the terephthalate derivative obtained by the above-mentioned method. A method for producing a terephthalate derivative is provided.

[0020] In one embodiment of the present invention, the transesterification reaction in step (a) is carried out at room temperature. The reaction can be carried out at a temperature range between the boiling points of the monohydric and / or polyhydric alcohol solvents as the reaction product, For every mole of dimethyl phthalate, the catalyst for transesterification is 0.00005 to 1.0 The molar ratio may be:

[0021] In one embodiment of the present invention, the alcohol in step (a) is ethylene glycol. It can be a rule.

[0022] The present invention also provides a polymer having an ester functional group, which is substituted with an alcohol, a polar aprotic Solvent and potassium carbonate (K 2 CO 3 (B) adding and depolymerizing the (A) step; The depolymerization product obtained in the second stage is subjected to a transesterification reaction while adding a carrier gas flow. (C) isolating and obtaining the terephthalate derivative produced by the reaction. The present invention relates to a method for producing a terephthalate derivative by depolymerization of a polymer containing an ester functional group. A method for producing a conductor is provided.

[0023] In one embodiment of the present invention, after step (A), a part of the compound is extracted from the depolymerization result. The part of the compound separated from the outside may be unreacted. Polymers containing ester functional groups, insoluble catalysts, polar aprotic solvents and reaction by-products The present invention may include at least one selected from the above.

[0024] In addition, the polar aprotic solvent in step (A) is effective for depolymerization of the polymer containing an ester functional group. It is inactive and does not participate in the synthesis reaction, and it can reduce the solubility of the catalyst in alcohol. The organic compound has a skeletal structure that is a chain and / or a cyclic compound, At least one of halogen elements, oxygen and nitrogen is bonded to the organic compound. toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetonium tolyl, propionitrile, aminopropionitrile, methylaminopropionitrile, Iminodipropionitrile, butyronitrile, methylbutenenitrile, butanenitrile , methyl ethyl ether, diethyl ether, ethyl phenyl ether, dimethoxybenzene Phenol, trimethoxybenzene, methoxyphenol, tetrahydrofuran, methyltetra Hydrofuran, dioxane, chloromethane, dichloromethane, chloroform, tetrachloroethane chlorobenzene, dichlorobenzene, and trichlorobenzene. There may be at least one of the above.

[0025] In addition, in one embodiment of the present invention, in step (A), a polymer having an ester functional group is The number of moles of the alcohol and the polar aproton relative to the number of moles of the repeating unit of the raw material The moles of the ester solvent are calculated based on the moles of the repeating units of the polymer raw material that contains the ester functional group. The ratio can range from 1 to 5,000 times.

[0026] In one embodiment of the present invention, before carrying out the transesterification reaction in step (B), The depolymerization product in step (A) may be treated with mono- and / or poly-esters as reactants for transesterification. Alcohol reactants of 1,2-dihydric alcohols, and / or alkali carbonates, alkali hydroxides, alkali alkoxides, Koxides, alkaline earth metal oxides and guanidine organic compounds The depolymerization product contains at least one transesterification catalyst selected from the group consisting of Adjust the amount of dimethyl terephthalate to a desired range per mole of dimethyl terephthalate added. The methanol recovered in step (C) can be used again as the depolymerization raw material in step (A). Can be reused.

[0027] In addition, in one embodiment of the present invention, the ester exchange reaction product prepared in step (B) is The catalyst is 0.00005 to 1 mole of dimethyl terephthalate contained in the depolymerization product. It is characterized by having a molar ratio of 1.0. Effect of the Invention

[0028] The present invention uses a simple process configuration that requires a small amount of transesterification catalyst and does not consume a lot of energy. We provide a method for obtaining highly-added terephthalate derivatives from DMT in high yields by More specifically, the method comprises the steps of: reacting a monomer raw material with a monohydric and / or polyhydric alcohol and an ethylene glycol; The methanol released by the ester exchange reaction changes the equilibrium that can be reached in a closed system. For example, a method of selectively discharging only methanol to the outside is used. This suppresses the reverse reaction, methanolysis, and promotes the forward reaction, transesterification. The present invention provides a method for producing a terephthalate derivative in high yield.

[0029] The reactant catalysts prepared according to an embodiment of the present invention are effective catalysts for transesterification reactions. Classification of reaction selectivity for methanolysis and transesterification reactions that produce derivatives. The quality of the catalyst used in the depolymerization reaction of polymers containing general ester functional groups is also improved. Even a small amount of 1 / 1000 to 1 / 10 of the amount of the substance can exert sufficient reactivity. To induce an effective and efficient transesterification reaction that can maintain selectivity. Therefore, the first reaction product discharged from the methanolysis reaction system was The transesterification reaction can be carried out with all or only a part of the catalyst remaining in the reactor. The vapor that is released is high-purity methanol equivalent to the amount of DMT, and most of it is concentrated and recovered. The recovered methanol can be used as a methanol for the depolymerization of polymers containing ester functional groups. It can be 100% recycled as a reactant for methanolysis, producing derivatives If this is combined with the ester exchange reaction that is involved, theoretically perfect methanol recycling is possible. It corresponds to technology.

[0030] The present invention also relates to DMT and ethylene glycol obtained from the depolymerization of polymers containing ester functional groups. The present invention provides a method for producing terephthalate derivatives in high yields by using ethylene glycol as a reaction intermediate. For example, in the presence of methanol, a polar solvent and a transesterification catalyst, The low-temperature methanolysis reaction can be carried out at room temperature to produce high yields of DMT and ethylene glycol. Then, ethylene glycol is added to the produced DMT through a transesterification reaction. It is possible to provide a method for producing BHET as a final product. By using this method to depolymerize polymers containing ester functional groups, the high-temperature reaction conditions of the existing glycolysis method can be Although the high temperature (190-280°C) is not used, the high yield of BHET, which is a highly-additive monomer, can be produced. For example, the diol reactant (e.g., ethylene glycol) can be A series of heating processes are carried out at temperatures close to room temperature, below the boiling point of methanol, and even lower than the boiling point of methanol. It is possible to selectively produce BHET in high yields through a single reaction process. This is due to the low temperature and low energy This means that it is possible to realize the glycolysis depolymerization technology of high energy.

[0031] The method according to the present invention produces less dimers or oligomers than existing high-temperature glycolysis reactions. The amount of oligomers produced can be kept low, and a relatively high concentration of BHET can be obtained. While it is possible to increase the temperature of the reaction mixture to remove impurities (including dimers and oligomers), The operating range of the purification process can be maintained similar to that of the conventional process, and the energy consumption in transporting the reactants can be reduced. It can be directly applied to the refining process without the costly preheating or cooling process, so it is energy-efficient. The amount of loss is minimized and continuous reaction and post-treatment steps can be easily realized.

[0032] The transesterification reaction that can be carried out according to the present invention is a method for producing a BHET which can be used for the repolymerization of PET. For the production of regenerated monomers or terephthalate derivatives that can be applied to the synthesis of various types of materials other than As an example, the monomers produced may have structures different from those of estrogen hormones. Due to its geometric properties, phthalates are known to cause hormone disruption in the human body. It can be used as a substitute for various kinds of plasticizers. PET can be used to manufacture raw materials for improving the thermal and mechanical properties of plastics. However, the final crystallization temperature is low and the crystallization rate is slow, so it is difficult to perform injection molding within a short cycle. It is known that it is difficult to synthesize such a compound, and its applications are limited due to such characteristics. Therefore, there is a market demand for various types of polymer resins with improved physical properties according to purpose and application. For example, the diol unit of PET is copolymerized with a new monomer. It is used in polycondensation to modify a portion of the diol to improve the physical properties of the final product. The method of producing ethylene glycol in the process of polycondensation is already widely used in industry. When butylene glycol was used instead of glycol for polymerization, the more flexible chain structure was obtained. This resulted in the production of polybutylene terephthalate (PBT) material, a polymeric form that is excellent for injection molding. In addition, by introducing different types of diols, it is possible to synthesize polymer materials in various forms. That is, in one embodiment of the present invention, the transesterification of DMT can be applied to the synthesis of Or, the reaction products of monohydric and / or polyhydric alcohols are modified and subjected to similar reaction conditions. In particular, it is possible to easily produce terephthalate derivatives in various forms from waste PET. The direct use of the reaction products produced from the methanolysis of The regenerated monomer can be produced economically through a simple reaction process, and the injection of raw materials can be different. This allows for the flexible production of a wide range of highly-added terephthalate derivatives. It is possible to configure an upcycling process. [Brief description of the drawings]

[0033] [Figure 1] 1 is a schematic diagram of a method for supplying a carrier gas to discharge methanol produced from the transesterification reaction of DMT to the outside of a reactor according to one embodiment of the present invention. [Diagram 2] 1 is a schematic diagram of an example of a process combination that can be configured to obtain a terephthalate derivative as a product in high yield by depolymerization from a polymer raw material containing an ester functional group according to an embodiment of the present invention. [Diagram 3] 1 is a schematic diagram of an example of an experimental setup for carrying out a transesterification reaction of DMT according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Unless otherwise defined, all technical and scientific terms used herein are defined by the principles of the present invention. have the same meaning as commonly understood by a person skilled in the art to which the term pertains. Generally, the nomenclature used herein is consistent with that which is well known and commonly used in the art. It is used.

[0035] Throughout this specification, when a part is described as "comprising" a certain element, this is specifically Unless otherwise stated, the term may further include other elements, rather than excluding other elements. This means that

[0036] The present invention uses DMT as a raw material and proceeds by adding monohydric and / or polyhydric alcohols. In order to obtain a highly-added terephthalate derivative in high yield when carrying out an ester exchange reaction that can be carried out This provides an optimal catalyst for

[0037] In one aspect, the present invention relates to a method for producing a terephthalate-based DMT product in high yield by a transesterification reaction. Alkali carbonates, alkali hydroxides, and alkali alkoxides have been used as catalysts for the conversion of ethyl ketone to its derivatives. Alkoxides, alkaline earth metal oxides and guanidine organic compounds The transesterification reaction method can be selected from at least one selected from the group consisting of Provide the law.

[0038] The present invention also provides a method for converting DMT to a terephthalate derivative by a glycolysis reaction. In addition to the optimum transesterification catalyst, optimum reaction conditions are set to produce terephthalate. The present invention provides a method for producing a terephthalate derivative derived from DMT, which can produce a terephthalate derivative in high yield. The present invention provides a transesterification method capable of carrying out the above-mentioned steps.

[0039] The method of the present invention comprises: (a) transesterifying DMT with monohydric and / or polyhydric alcohols; Addition of alkali carbonates, alkali hydroxides, and alkali alkalates as reactants for the conversion reaction a metal oxide, an alkaline earth metal oxide, and a guanidine-based organic compound; and adding a carrier gas flow in the presence of at least one transesterification catalyst. (b) carrying out a transesterification reaction of the terephthalate derivative produced by the reaction. and a step of separating and obtaining the same.

[0040] In the present invention, the introduction of the catalyst and the flow of the carrier gas in the step (a) are performed in such a manner that the reactants are The reaction can be fed without restriction before or after the temperature is reached, and can be run under batch reaction conditions or The catalyst and the addition product mono- and / or polyhydric arsenic are reacted under continuous flow conditions. Coal may also be added in a mixed form with DMT prior to setting up the reaction.

[0041] The flow of carrier gas is used as a means for discharging the methanol to the outside, A forced circulation of the gas phase using a pressure gradient can be used. After condensing the methanol vapor externally, the gas is recycled in a nearly lean vapor phase. Either a continuous flow is used (Figure 2a) or an external inert gas is continuously supplied to the A method of discharging methanol to the outside (Figure 2b) can also be used.

[0042] In carrying out the transesterification reaction in step (a), dimethyl terephthalate, Monohydric and / or polyhydric alcohol and a catalyst for transesterification are added, and the carrier gas is introduced into the The transfer pipe is connected to the reactant water level so that the gas and liquid can directly contact with the reactant in the reactor. The gas phase of methanol can be injected into the gas phase by placing it under the A vapor concentration is formed and is continuously discharged to the outside via the outward flow of the carrier gas. Methanol vapor diffused by the carrier gas undergoes mass transfer at or above the saturation concentration. However, if a carrier gas is provided at a sufficient velocity, the ester will The amount of methanol discharged can be adjusted by the rate of the methanol exchange reaction.

[0043] The temperature of the transesterification reaction is generated from the reaction during the gas-liquid contact process or within the reactants. The evaporation rate of methanol present in the reaction mixture is in the range from room temperature to the temperature range applied to the reactants. The temperature and absolute pressure between the boiling point of the monohydric and / or polyhydric alcohols are 0.1t The pressure can be maintained at orr~5 atm, but the temperature required for the transesterification reaction is The above range is taken into consideration together with the pressure range and the methanol removal rate by the carrier gas. can be changed within.

[0044] The above temperature range can be changed depending on the transesterification catalyst to be added, and preferably, The temperature is between room temperature and the boiling point of the alcohol applied to the reactant, and the pressure is It may be advantageous for stable and continuous process operation to carry out the process at a pressure close to atmospheric pressure. The reaction time in step a) is determined by the type and amount of catalyst used in the reaction, as well as the amount of catalyst supplied. It may also vary depending on the amount of DMT and alcohol.

[0045] First, in the step (a), the transesterification reaction is carried out at a rate of 1000 times per unit mole of the raw material DMT. The catalyst used has a molar ratio of 0.00005 to 1.0, preferably 0.0001 to 0.2. The ester exchange reaction catalyst can be added so as to have a DM as a raw material. When contained in a molar ratio of less than 0.00005 per unit mole of T, monovalent and / or polyvalent The transesterification of DMT with hydroxyl alcohols proceeds slowly, which can reduce process efficiency. When the molar ratio exceeds 1.0, the catalyst content is increased. Since the effect of increasing the amount of chlorine is not large, it is uneconomical and may increase by-products. During the separation of the terephthalate derivative, the excess catalyst remains as an impurity. This can affect the efficiency of separation and purification.

[0046] The transesterification catalyst is an alkali carbonate, an alkali hydroxide, an alkali alkoxide, oxides, alkaline earth metal oxides, and guanidine-based organic compounds. At least one, preferably K 2 CO 3 , K.H.C.O. 3 , Na 2 CO 3 , NaHCO 3 , NaOH, KOH, MgO, CaO, CH 3 OK, C.H. 3 Choose from ONa and TBD At least one of the catalysts is used, and the amount and combination of the catalysts significantly improves the conversion rate of DMT. At the same time, the yield of the terephthalate derivative can be significantly improved. Must be.

[0047] The amount of ethylene glycol in step (a) is in the range of 1 to 50 moles per mole of DMT. When the amount of ethylene glycol is within the above range, the most efficient esterification can be achieved. A reaction may occur.

[0048] The monohydric and polyhydric alcohols may be linear, branched, cyclic or any combination thereof having 1 to 20 carbon atoms. The alcohol may be of mixed form, and the OH functionality of the polyhydric alcohol may be two or more. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, and ethanol. isopropanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, At least one of glycerol and 1,2,4-butanetriol can be used, and preferably Preferably, ethylene glycol can be used.

[0049] In this way, monohydric and / or polyhydric alcohols are converted into DMT in the presence of the transesterification catalyst. In the step (a) of carrying out an ester exchange reaction by adding terephthalate derivative and methanol, The forward reaction to the terephthalate derivative product proceeds at or above the equilibrium concentration. To continue this, a carrier gas flow was placed inside the reactor, and methanol vapor was pumped outside the reaction system. The method of supplying the carrier gas is shown in Figure 2. As shown in the figure, the methanol vapor is separated by a condenser and then discharged to the outside. (b) of Fig. 2 or by removing the methanol vapor and then recycling it (Fig. 2 a) can be used.

[0050] The carrier gas injected into the reactor is used to reverse react with methanol, a by-product of the transesterification reaction. The amount of methanol in the reactants can be prevented or suppressed from recombining through the reaction. Reaction conditions that maintain a low concentration improve DMT conversion and terephthalate derivative product yields. In this case, the carrier gas is preferably used for the alcohol-addition ester exchange of DMT. Any gas that does not have a chemical effect on the exchange reaction or the catalyst can be used without restriction, and preferably air. Gas, nitrogen, argon, helium, etc. can be used, and preferably, a gas that does not substantially contain moisture. An inert gas that does not cause oxidation may be advantageous.

[0051] In the present invention, the step (b) comprises separating the terephthalate derivative formed in the reaction. Specifically, the terephthalate derivative formed in the step (a) is It is separated from the reaction mixture, which contains unreacted residual DMT, ethylene glycol, residual catalyst, etc. The step of obtaining a high purity product can be carried out by a generally known purification method, and the method is not limited. However, physical methods such as filtration, crystallization, centrifugation, evaporation, distillation, etc., or adsorption, neutralization, salting out, Chemical methods such as the above can be carried out in parallel.

[0052] The present invention relates to an ester capable of adding monohydric and / or polyhydric alcohols to DMT as a starting material. In producing a highly-added terephthalate derivative by an alkylation reaction, the DMT is The depolymerization result is obtained by depolymerizing a polymer containing a steric functional group, and the depolymerization result is subjected to a pretreatment process. The ester exchange reaction is carried out with monohydric and / or polyhydric alcohols with or without the addition of Thus, a terephthalate derivative can be produced.

[0053] The transesterification reaction by addition of monohydric and / or polyhydric alcohols to DMT is carried out by the following procedure: The reaction product produced by the methanolysis reaction from the polymer raw material containing the functional group is a second High yields of terephthalic acid were obtained by two-step tandem reaction, which was used directly as a feedstock for the transesterification reaction. It can also be applied to the reaction process for producing tallate derivatives.

[0054] That is, the present invention is directed to initiating the depolymerization of polymers containing ester functional groups to produce final products. A method for producing a terephthalate derivative is provided, comprising: (A) reacting a polymer containing an ester functional group with the polymer; Alcohols, polar aprotic solvents and potassium carbonate (K 2 CO 3 ) is added to depolymerize (B) adding a carrier gas flow to the depolymerization product obtained in (A). (C) carrying out a transesterification reaction while the terephthalate produced by the reaction is reacted with the terephthalate. and isolating and obtaining a product ester derivative. A method for producing high addition terephthalate derivatives by depolymerization of the molecule is provided.

[0055] FIG. 1 shows a process for producing terephthalic acid by transesterification from a polymer raw material containing an ester functional group. 1 is a conceptual diagram of a process for producing a tallow derivative. First, in step (A), (100) is a polymer containing ester functional groups, and is used in the reaction of alcohols, polar aprotic solvents, and carbon. Potassium phosphate (K 2 CO 3 ) into a depolymerization reactor and depolymerizing the ester, Polymers containing terephthalic functional groups are reacted with alcohols, polar aprotic solvents and potassium carbonate (K 2 CO 3 ) to produce an alcohol-added monomer by an ester exchange reaction. This effectively depolymerizes the polymer at low temperature. The process is very simple and has a 90% DMT can be obtained in high yields and is very economical due to its low energy consumption. do.

[0056] Here, the polymer containing the ester functional group is in the form of a single or mixed waste plastic, e.g. For example, polyethylene, high density polyethylene, low density polyethylene, polypropylene or the like. These combinations may be in admixture with the polymer containing the ester functionality. Other polymers that may be mixed with the polymers containing ester functional groups listed above may be simply By way of example only and not limitation, the above.

[0057] Polymers containing ester functional groups are formed by condensation polymerization of dicarboxylic acids and dialcohols. The dicarboxylic acid may be terephthalic acid, naphthalene dicarboxylic acid, or the like. Carboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl Sulfondicarboxylic acid, diphenoxyethanedicarboxylic acid, succinic acid, adipic acid, sebacic acid Acid, Azelaic Acid, Decanedicarboxylic Acid, Cyclohexanedicarboxylic Acid, Trimellitic Acid and the dialcohol is selected from the group consisting of: Ethylene glycol, trimethylene glycol, 1,2-propanediol, tetramethylene ethylene glycol, neopentyl glycol, hexamethylene glycol, decanmethylene Glycol, dodecamethylene glycol, 1,4-cyclohexanedimethanol, diethylene Ethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol Recall, dipropylene glycol, tripropylene glycol, tetrapropylene glycol Coal, polypropylene glycol, di(tetramethylene) glycol, tri(tetramethyl) (ethylene) glycol, polytetramethylene glycol, pentaerythritol, 2,2- Bis(4-β-hydroxyethoxyphenyl)propane and combinations thereof is selected from the group.

[0058] As an example, the polymer containing the ester functional group is polyethylene terephthalate (PET). ), polypropylene terephthalate (PPT), polyglycolide or polyglycolic acid ( PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkane Polyhydroxybutyrate (PHA), Polyhydroxybutyrate (PHB), Polyethylene adipate ( PEA), polybutylene succinate (PBS), poly(3-hydroxybutyrate-c o-3-hydroxyvalerate (PHBV), polybutylene terephthalate (PBT) , Polytrimethylene terephthalate (PTT), Polyethylene naphthalate (PEN), Vectran and combinations thereof.

[0059] One of the most common examples of polymers containing ester functional groups is polyethylene terephthalate. (PET), where the starting material for the preparation of the polymer is terephthalic acid or its Derivative monomer and ethylene glycol.

[0060] The polymers containing ester functional groups used in the present invention are not in a pure state, but contain various impurities. For example, in addition to polymers containing ester functional groups, bottle caps This includes, but is not limited to, scraps, adhesives, paper, liquid residue, dust or combinations thereof. A mixture of crude debris can be used as the feedstock for depolymerization.

[0061] The alcohol is a reactant and is preferably a linear primary alcohol, e.g. For example, methanol, ethanol, propanol, butanol, or combinations thereof. obtain.

[0062] The alcohol is added in an amount of 1 mole per mole of the repeating unit of the polymer raw material containing the ester functional group. The mole number of the alcohol is in the range of 0.1 to 5,000, preferably 1 to 500. Can be used in a range.

[0063] The catalyst used is potassium carbonate, which has the chemical formula K 2 CO 3 In table The potassium carbonate is in anhydrous form rather than in hydrated form. It is preferable to use calcium carbonate, and it is more preferable to dry it before use. The amount of sodium used should be at least 0.01 times the number of moles of the repeating units of the polymer containing the ester functional group. The ratio may be preferably 0.01 to 100 times, and more preferably 0.1 to 10 times.

[0064] The polar aprotic solvent is active in the decomposition reaction or transesterification reaction of the ester functional group. It is used as an organic liquid compound that can be applied to reduce the conversion energy and does not directly participate in the reaction. It is a non-reactive, inert solvent that does not react with Heterogeneous catalytic reaction by reducing the solubility of the catalyst (potassium carbonate) in the reactant (alcohol) The reaction thermodynamics are favorable to be able to derivatize and dissolve the resulting monomer.

[0065] The backbone structure of the organic compound in the polar aprotic solvent is a chain or cyclic compound. The halogen element may be directly bonded to the organic compound, or may be bonded to the organic compound by oxygen or nitrogen. The compounds may be in the form of themselves or linked to each other. Specific examples thereof include: Toluene, acetone, methyl ethyl ketone methyl isobutyl ketone tone), acetonitrile, tetrahydrofuran trahydrofuran, dichloromethane , chloroform, chlorobenzene e), methyl phenyl ether, methyl phenyl At least one selected from among ethyl phenyl ether Seeds can be used.

[0066] The polar aprotic solvent is preferably a repeating unit of the polymer raw material containing the ester group. The molar ratio is in the range of 0.1 to 5,000 times, preferably 1 to 500 times, relative to the molar ratio of A range of rates can be used.

[0067] The step (A) is carried out at a temperature in the range of 0 to 80° C., preferably 10 to 60° C., to form a carboxylic acid compound containing an ester functional group. In order to depolymerize a polymer containing the alcohol by addition reaction, according to some examples of the above (A), It is possible to induce complete decomposition of polymers at room temperature and has a simple structure and composition. This makes it possible to realize a reaction system that is superior to existing technologies or processes. This may result in lower investment costs and allows for efficient and stable energy management.

[0068] On the other hand, the depolymerization in step (A) can be carried out using a heterogeneous, low-cost catalyst that is essentially water-soluble. Since the catalyst is used in the reaction, it is easy to recover and reuse the catalyst after the reaction. The monomer produced can be recovered at a high rate by lowering the temperature, and the solvent used can be recycled. Economical recycling process because it can be reused as depolymerization raw material for new polymer raw materials can be further improved.

[0069] In addition, the depolymerization of the polymer in the step (A) can be carried out without the input of an additional heat source. The heat of mixing and dissolution generated during the process of producing the reaction mixture is the only heat required for depolymerization. In this case, the depolymerization can be carried out in an insulated reactor. In some embodiments of the present invention, the decomposition can be performed while supplying an external heat source. It is also possible to combine

[0070] The depolymerization of the polymer can be carried out at atmospheric pressure or higher. It can be performed at pressures of up to 6.5 atm.

[0071] The depolymerization of the polymer can be carried out in an open or closed system. Alternatively, a condenser may be placed to reflux the solvent.

[0072] The depolymerization reaction time in step (A) varies depending on the amount of polymer used, but it is At room temperature without adding any oxygen, it is possible to obtain monomers in sufficiently high yields within 24 hours. The substances other than the reactants do not undergo any serious chemical changes and can be almost entirely recovered. can be reintroduced into the process.

[0073] After the step (A), a part of the compound is released from the depolymerization resultant obtained by depolymerization. A separation step (200) can be further carried out. Specifically, the part of the compounds can be separated by The step of separating the DMT from the polymerization result is carried out by removing the DMT from the polymerization product obtained after the completion of the depolymerization reaction in step (A). and unreacted materials remaining with ethylene glycol, methanol, polar aprotic solvents, Catalyst or mono-methyl terephthalate te (MMT), terephthalic acid (TPA) derivative The polymer, insoluble catalyst and polar non-protons are separated from the reaction mixture 10, which includes by-products such as condensed polymers. A flow containing at least one selected from the group consisting of an olefin solvent, a reaction by-product, etc. is separated to the outside. Since the steps can be carried out by a commonly known method, the method is not limited. stomach.

[0074] As an example of separation, the insoluble catalyst and unreacted polymer are separated from the depolymerization product by filtration. When separated, the depolymerization product is in the form of a homogeneous liquid, and the depolymerization product is then added to the depolymerized product. Part or all of the polar aprotic solvent or methanol is evaporated or distilled at high temperature or reduced pressure. When distilled, the DMT in the depolymerization product may crystallize. Methods to increase the concentration of DMT include adding more washings, recrystallization, physical filtration, and distillation. Further methods such as distillation, evaporation, and drying are used to obtain the raw material for the ethylene glycol addition transesterification reaction. The solvent and catalyst separated from the depolymerization product can be prepared as a raw material. It can be reintroduced (20) as a raw material for the methanolysis depolymerization 100, which is step A).

[0075] Meanwhile, the step of separating the part of the compounds (200) may include isolating monovalent and / or substituted DMTs. or a polyhydric alcohol is added to prepare the transesterification step (300). It may be a step that is carried out, but it does not necessarily mean that it should be carried out. and separating the depolymerization product obtained from the depolymerization step of the polymer containing the ester functional group of the step. It may also be used directly as a raw material for step (B) without going through step (200). It is Noh.

[0076] In the present invention, step (B) (300) is a step of adding a capping agent to the depolymerization product obtained in step (A). This is the stage where the transesterification reaction is carried out while adding the rear gas flow 3. The method for carrying out the transesterification reaction is the above-mentioned method for producing a terephthalate derivative from DMT. The DMT in step (B) is carried out in the same manner as in step (B), so a detailed description thereof will be omitted. The polymer is obtained by depolymerization of a polymer containing an ester functional group (30), The polymerization can be carried out by a simple process at room temperature and pressure, and the product of depolymerization is highly This contains DMT and polyhydric alcohol in a yield of 100%, and this is again obtained by extracting DMT from the above-mentioned specification. By using the method for producing terephthalate derivatives, it is possible to obtain polymers containing ester functional groups. From this, a terephthalate derivative can be obtained directly as the final product.

[0077] Before the transesterification reaction in step (B), an ester is added to the depolymerization product in step (A). Monohydric and / or polyhydric alcohols and / or alkalis as solvents for the alcohol exchange reaction Carbonates, alkali hydroxides, alkali alkoxides, alkaline earth metal oxides and guanidine At least one transesterification reaction catalyst selected from the group consisting of phenol-based organic compounds, The number of moles per mole of dimethyl terephthalate contained in the depolymerization product is within a predetermined range. The ester exchange reaction can also be carried out after adjusting the temperature as described above.

[0078] The adjustment of the moles of the alcohol and / or the transesterification catalyst may be carried out by adjusting the moles of the alcohol and / or the transesterification catalyst. Alternatively, a transesterification catalyst is added to the depolymerization product or is extracted from the depolymerization product. During the partial removal process or after partial removal, new monohydric and / or polyhydric alcohols are added. In this case, the above-mentioned removal and addition processes are carried out by the above-mentioned partial chemical process. This may be accomplished by separating the mixture (200).

[0079] The newly added monohydric and / or polyhydric alcohol is a linear alcohol having 1 to 20 carbon atoms, The alcohol may be branched, cyclic or a mixture thereof, and the polyhydric alcohol The OH functional groups are two or more.

[0080] The mole number of ethylene glycol after the adjustment is the mole number of terephthalic acid contained in the depolymerization result. The amount of the dimethyl ester is in the range of 0.1 to 100 moles, preferably in the range of 1 to 50 moles. It is possible.

[0081] In addition, the mole number of the catalyst for transesterification after adjustment is determined based on the mole number of the terephthalic acid contained in the depolymerization product. In the range of 0.00005 to 1.0 moles per mole of dimethyl phthalate, preferably 0.00 The molar ratio may range from 0.1 to 0.2 moles.

[0082] In the transesterification reaction 300, the reverse reaction caused by methanol is suppressed, and the product In order to sustain the addition reaction of monohydric and / or polyhydric alcohols in the direction of the production of The carrier gas stream 3 allows the methanol to be discharged (40) outside the reactor. The methanol recovered through the condenser 400, which is maintained at a low temperature, is used for the decomposition of the (A) stage. This can be reused as a raw material for the synthesis reaction (60). 0 °C range) compared to the existing glycolysis method for producing BHET. The reaction proceeds rapidly even at low temperatures, much lower than the boiling points of the monohydric and / or polyhydric alcohols. Therefore, the terephthalate derivative products can be obtained effectively. Since the reaction pathways leading to the final product are different, decomposition (or depolymerization) in the product proceeds less. The products that are generated (dimers or oligomers) may occur in relatively low concentrations or may not occur at all. However, terephthalate derivatives can be obtained in high yields.

[0083] According to the method of the present invention, the reactivity in the low temperature range and the efficiency of the purification process are improved, This will allow for a significant reduction in energy consumption compared to existing processes, resulting in and to provide a means for economically producing a highly-added terephthalate derivative. can be done.

[0084] In the present invention, step (C) is a step of producing a high yield of a terephthalate derivative by the reaction. The step of obtaining the terephthalate derivative from the DMT (500) is described above. Since this can be done in a similar manner to the manufacturing method for the above-mentioned embodiment, detailed description thereof will be omitted.

[0085] The following comparative examples and examples are provided to illustrate the process of the present invention. The following examples are merely representative examples for the purpose of illustration, and the scope of the present invention is not limited to these examples. It is not something that can be achieved.

[0086] Raw material 1 (dimethyl terephthalate raw material) Dimethyl terephthalate (Sigma-Aldrich, c) was supplied by a reagent manufacturer. atal.#185124, purity >99.0%) was ground uniformly using a pestle and mortar. A fine powder was prepared as raw material 1.

[0087] Raw material 2 (polymer raw material containing ester functional groups) A polymeric substance containing an ester functional group, which is waste polyethylene terephthalate discharged after consumption. The bottles of tarate material are washed to remove any residual foreign matter, dried, and then passed through a continuous grinding mill ( The powder was crushed using an IKA MF10.1 (manufacturer and model) and then sieved using a standard sieve. The width and length of the wide surface are 1 to 3 mm, and the thickness is 0.5 mm. Only plastic chips having a size of 0.1 mm or less were collected and prepared as raw material 2.

[0088] <Example 1> Approximately 14.5g of DMT raw material prepared according to the procedure for Raw Material 1 and a dihydric alcohol polar solvent Ethylene glycol (Sigma-Aldrich; purity ≥ 99.8%) as a 5.6g (equivalent to 12 moles of raw material 1) was placed in a three-neck flask and cooled. After installing a distillation apparatus with a refrigerator, use a magnetic stirrer and heat at a speed of 1,200 rpm. Stirring was started at 30°C.

[0089] To effectively remove the reaction product, methanol, a high-temperature inert carrier gas was used. Use nitrogen of high purity (manufactured by Central Industrial Gas; 99.9992%) to avoid contact with the liquid in the reactor. The gas flow rate was 200 sccm, or normalized to the volume of the initial reaction mixture under standard conditions. Gas Hourly Space Velocity (GHSV(hr -1)) the mass flow controller is set so that the set value is kept constant at 240. The flow rate was adjusted using a mass flow controller.

[0090] Then, start heating the flask containing the reactants until the final temperature of the reaction solution reaches 80°C. As a catalyst, potassium carbonate (K 2 CO 3 , potassium carbonate Approximately 0.05 g (Sigma-Aldrich, ACS reagent) was added. After the reaction was started, a total of 8 By carrying out a transesterification reaction for a long time, BHET was obtained as a highly depolymerizable monomer. As the reaction proceeds, the methanol produced is transported by the carrier gas. The gas was removed from the reactor and discharged to the outside of the reactor. Collected by:

[0091] During the reaction, a small amount (50 mg or less) of the liquid reactant was collected at each time point, and then the standard sample was High performance liquid chromatography (HPLC) with Optimapa k C18 Column (250mm, 5micron), UV detector (λ=254nm The distribution and concentration of the products were estimated from the quantitative analysis using the The yield of each product was calculated. In the HPLC analysis, the mobile phase was methanol:water. A mixed solution with a volume ratio of 70:30 was used, and the total flow rate was maintained at 0.7 ml / min.

[0092] The conversion rate of DMT by transesterification and the amount of esters produced by the alcohol reactants from DMT were Intermediate products in which the ester exchange reaction has partially progressed (e.g., ethylene glycol-added ester exchange reaction) In the case of the transesterification reaction, HEMT), the monomer product that is generated when the transesterification reaction has progressed completely ( For example, in the case of ethylene glycol addition transesterification, BHET), dimers, and side reactions The products potassium monomethyl terephthalate (K-MMT) and dipotassium terephthalate M(K 2 The yield of -TPA was calculated using the following formula:

[0093] DMT conversion rate = (N 0 -N) / N 0 (Formula 1) Monomer yield = (N monomer / N 0 )×100% (Formula 2) Yield of intermediate = (N intermediate / N 0 )×100% (Formula 3) Yield of MMT = (N MMT / N 0 )×100% (Formula 4) Yield of TPA = (N TPA / N 0 )×100% (Formula 5) Dimer yield = (N dimer / N 0 )×100% (Formula 6)

[0094] In the above formula, N 0 is the number of moles of DMT, the initial raw material, and N,N interm ediate , N monomer , N MMT , N TPA and N dimer is unconverted D MT, intermediate products, monomer products, MMT, TPA and dimer terephthalate is the number of moles.

[0095] <Comparative Example 1> The same method as in Example 1 was used except that potassium carbonate was not added. The transesterification reaction was carried out and evaluated.

[0096] <Example 2> In Example 1, about 0.001 g of potassium carbonate (0.0001 molar ratio to raw material 1) was used. The transesterification reaction was carried out in the same manner as in Example 1, except that 100 moles of ethanol was used. It was implemented and evaluated.

[0097] <Example 3> In the above Example 1, about 0.01 g of potassium carbonate (0.001 times the molar ratio of raw material 1) was used. The transesterification reaction was carried out in the same manner as in Example 1, except that the ester was replaced with 1,000 mol of ethyl acetate. and evaluated.

[0098] <Example 4> In the above Example 1, about 0.1 g of potassium carbonate (0.01 times the molar amount of raw material 1) was used. The transesterification reaction was carried out in the same manner as in Example 1, except that the esters used were the same as those used in Example 1. Evaluated.

[0099] <Example 5> In the above Example 1, about 0.5 g of potassium carbonate (0.05 times the molar amount of raw material 1) was used. The transesterification reaction was carried out in the same manner as in Example 1, except that the esters used were the same as those used in Example 1. Evaluated.

[0100] <Example 6> In the above Example 1, about 2.1 g of potassium carbonate (0.2 times the molar amount of raw material 1) was used. The ester exchange reaction was carried out and evaluated in the same manner as in Example 1, except that a styrene-containing styrene-containing styrene-containing styrene was used. did.

[0101] <Comparative Example 2> The same method as in Example 1 was used except that no inert carrier gas was used. The transesterification reaction was carried out and evaluated.

[0102] <Example 7> In the above Example 1, high purity nitrogen was used as the inert carrier gas at 50 sccm (GHS V=60h -1 The transesterification reaction was carried out in the same manner as in Example 1, except that the temperature was kept at 100° C. It was implemented and evaluated.

[0103] <Example 8> In the above embodiment 1, high purity nitrogen was used as the inert carrier gas at 100 sccm (GH SV=120h -1 The transesterification reaction was carried out in the same manner as in Example 1, except that the temperature was kept at 100° C. The response was implemented and evaluated.

[0104] <Example 9> In the above-mentioned Example 1, high-purity nitrogen was used as the inert carrier gas at 500 sccm (GH SV=600h -1 The transesterification reaction was carried out in the same manner as in Example 1, except that the temperature was kept at 100° C. The response was implemented and evaluated.

[0105] <Example 10> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 50° C. The transesterification reaction was carried out and evaluated.

[0106] <Example 11> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 65° C. The transesterification reaction was carried out and evaluated.

[0107] <Example 12> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 100°C. The transesterification reaction was carried out and evaluated by this method.

[0108] <Example 13> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 110° C. The transesterification reaction was carried out and evaluated by this method.

[0109] <Example 14> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 120°C. The transesterification reaction was carried out and evaluated by this method.

[0110] <Example 15> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 130° C. The transesterification reaction was carried out and evaluated by this method.

[0111] <Example 16> The same procedure as in Example 1 was carried out except that the temperature of the reaction solution was maintained at 140° C. The transesterification reaction was carried out and evaluated by this method.

[0112] <Example 17> In Example 1, potassium bicarbonate (KHCO 3 ) to about 0.008g (raw The reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0113] <Example 18> In Example 1, sodium carbonate (Na 2 CO 3 ) to approximately 0.008g ( The reaction time was kept at 3 hours. Except for the above, the transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0114] <Example 19> In Example 1, sodium bicarbonate (NaHCO 3 ) about 0.006g (equivalent to 0.001 times the molar amount of raw material 1) and maintain the reaction time for 3 hours. Except for the above, the transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0115] <Comparative Example 3> In the above Example 1, about 0.007 g of potassium acetate (KOAc) was used as a catalyst (raw material 1). (equivalent to 0.001 times the molar amount of 1,000 ethanol) and the reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0116] <Comparative Example 4> In the above Example 1, about 0.006 g (raw material) of sodium acetate (NaOAc) was used as a catalyst. The reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0117] <Comparative Example 5> In Example 1, zinc acetate (Zn(OAc) 2 2H 2 O) to approximately 0.0 1g (equivalent to 0.001 times the molar amount of raw material 1) was used, and the reaction time was kept at 3 hours. Except for the above, the transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0118] <Example 20> In the above Example 1, about 0.004 g of potassium hydroxide (KOH) was used as a catalyst (raw material 1 (equivalent to 0.001 times the molar amount of 1,000 ethanol) and the reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0119] <Example 21> In the above Example 1, about 0.003 g (raw material) of sodium hydroxide (NaOH) was used as a catalyst. The reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0120] <Example 22> In Example 1, potassium methoxide (CH3 OK) about 0.005g (equivalent to 0.001 times the molar amount of raw material 1) and maintain the reaction time for 3 hours. Except for the above, the transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0121] <Example 23> In Example 1, sodium methoxide (CH 3 ONa) to approximately 0.00 4g (equivalent to 0.001 times the molar amount of raw material 1) was used, and the reaction time was kept at 3 hours. Except for the above, the transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0122] <Example 24> In the above Example 1, about 0.003 g of magnesium oxide (MgO) was used as a catalyst (raw material The reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0123] <Example 25> In the above Example 1, about 0.004 g of calcium oxide (CaO) was used as a catalyst (raw material 1). (equivalent to 0.001 times the molar amount of 1,000 ethanol) and the reaction time was kept at 3 hours. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0124] <Example 26> In Example 1, triazabicyclodecene was used as a catalyst. odecene, TBD) about 0.01g (corresponding to 0.001 times the mole number of raw material 1) The same procedure as in Example 1 was used, except that the reaction time was kept at 3 hours. A cyclohexane exchange reaction was carried out and evaluated.

[0125] <Comparative Example 6: PET depolymerization by high-temperature glycolysis reaction> Approximately 10 g of PET raw material 2 was prepared as the raw material for the glycolysis reaction. Approximately 38.75 g of ethylene glycol, a polar solvent (equivalent to the molar amount of the repeating unit of the polymer), was used. (12 moles per unit) was placed in a three-neck flask, a reflux condenser was attached at atmospheric pressure, and the flask was heated with a The mixture was heated and stirred using a magnetic stirrer. When the temperature reached 177°C, the prepared 10 g of polymer raw material was added, and the temperature was increased while stirring. When the reaction mixture reached 197°C or When the reflux temperature was reached, about 0.571 g of zinc acetate catalyst (equivalent to the molar amount of the polymer repeat unit) was added. The catalytic reaction was started by adding 0.05 mol per 100 ml of ethanol. The reaction was stirred continuously for 2 hours, but the reaction temperature was is maintained constant within ±0.5°C, using a condenser with one end exposed to atmospheric pressure. After the reaction, the unreacted material in the resultant was separated and quantified by filtration. Monomers, dimers, and by-products of monohydroxyethyl terephthalate (mono(h Hydroxyethyl terephthalate, MHET, and oligomers The method used to quantify the reactants in Example 1 was similar to that used in the pre-calibration of standards. After quantification using high performance liquid chromatography, the distribution and concentration of the products were estimated.

[0126] <Example 27: PET depolymerization by room temperature methanolysis and low temperature glycolysis> Approximately 3g of PET raw material prepared according to raw material 2 and dichloromethane (Samchun P ure Chemical Ind. Co. Ltd; purity 99.5%) approx. 66.3g (original) Feedstock 2: 50 times the molar number of the repeating unit of the polymer, methanol (Samch un Pure Chemical Ind. Co. Ltd ;99.9%)24.96g (equivalent to 50 times the molar number of repeating units of the raw material 2 polymer), and K as a catalyst. 2 CO 3 (Potassium carbonate; Sigma-Aldrich, ACS reagent) Approx. 0 0.43g (equivalent to 0.2 times the molar number of the repeating unit of raw material 2 polymer) was added to a three-port flask. Add secondary distilled water to the reactants so that the initial water content of the reactants is 1 / 100 of the repeating unit of the raw polymer. The magnetic stirrer was adjusted to have an initial molar ratio of 0.4 to 1. The reaction was carried out at 25° C. and atmospheric pressure for 24 hours with stirring at 500 rpm.

[0127] After the reaction, the resultant was filtered to separate DMT, HEMT, ethylene glycol, and potassium MMT. The filtrate contains organic solvents and a portion of the K-MMT, which is a ammonium salt. ), and unreacted PET, K 2 CO 3 Catalyst, solids including K-MMT (filter c The mixture was separated into two parts:

[0128] The potassium salts in the filtrate and solids were taken in small amounts (50 mg or less), and then transferred to the The samples were prepared by diluting with aqueous phase chromatography (HPLC). h Optimapak C18 Column (250nm, 5micron), UV inspection Quantitative analysis using a detector (λ=254 nm) was used to estimate the product distribution and concentration in each sample. The amount of unreacted PET in the solids was determined by gravimetry. The conversion rate of PET by HPLC and the yields of DMT, HEMT, TPA, and MMT were calculated. During the analysis, a mixed solution of methanol and water with a volume ratio of 70:30 was used as the mobile phase. The total flow rate was maintained at 0.7 ml / min.

[0129] The PET conversion rate and DMT yield in the depolymerization reaction were calculated using the following formulas.

[0130] PET conversion rate = (M 0 -M) / M 0 ×100% (Formula 7) Yield of DMT = (M DMT / M 0 )×100% (Formula 8)

[0131] In the above formula, M 0 and M are the initial raw polymer (PET) and the unreacted polymer, respectively. The number of moles of repeating units of the molecule is indicated, M DMT indicates the number of moles of DMT produced.

[0132] The filtrate of the depolymerization product is used as a raw material to perform transesterification by adding ethylene glycol. The transesterification reaction was carried out under the same conditions as in Example 1, but The filtrate of the depolymerization product was used instead of raw material 1 as the raw material, and methanol and a polar non-proline were added. Most of the volatile solvent was removed using a vacuum evaporator. After that, the moles of DMT were the same as in Example 1. The ethylene glycol was adjusted so that it was generated by depolymerization and further added. The total weight is about 55.6g (12 times the molar ratio of DMT). The transesterification reaction was carried out and evaluated without the addition of additional catalyst. Ta.

[0133] The moles of catalyst and K-MMT in the solid matter recovered after filtration were determined using gravimetric and HPLC methods. The molar ratios of the repeating units of the raw materials were 0.126 and 0.024, respectively. (measured by the moles of catalyst initially charged, excluding those recovered as solid phase) The number of moles (based on the number of moles of potassium cation) is the number of moles of the residual catalyst in the filtrate of the depolymerization product. From this, the catalyst in the raw material for the transesterification reaction in which ethylene glycol is added was calculated. (K 2 CO 3 ) is present in a ratio of about 0.054 moles per mole of DMT. I understand.

[0134] Conversion rate of DMT by transesterification, and yields of BHET, HEMT, and BHET dimer was calculated using the above-mentioned formulas 1 to 4, and the results are shown in Table 5.

[0135] <Example 28> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount 1,3-propanediol (Sigma-Aldrich) (12-fold molar ratio to the number of moles of DMT unit) Aldrich (purity ≥ 98%) was used, and the reaction temperature was maintained at 100°C. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0136] <Example 29> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount 1,4-butanediol (Sigma-Aldrich) (12 times the molar ratio of DMT units) ReagentPlus (registered trademark, purity ≥ 99%) manufactured by Idrich was used for the reaction solution. The transesterification reaction was carried out in the same manner as in Example 1, except that the temperature was kept at 100°C. It was implemented and evaluated.

[0137] <Example 30> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount 1,6-Hexanediol (Sigma-Aldrich) (12 times the molar ratio of DMT units) Aldrich (purity ≥ 99%), and the reaction temperature was maintained at 100°C. The transesterification reaction was carried out and evaluated in the same manner as in Example 1.

[0138] <Example 31> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount 1,2-propanediol (Sigma-Aldrich) (12-fold molar ratio to the number of moles of DMT unit) Aldrich; ReagentPlus (registered trademark, purity ≥ 99%) was used, and the reaction solution The transesterification reaction was carried out in the same manner as in Example 1, except that the temperature was kept at 100°C. It was implemented and evaluated.

[0139] <Example 32> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount 1,3-butanediol (Sigma-Aldrich) (12 times the molar ratio of DMT units) Anhyrous (manufactured by Idrich, purity ≥ 99%) was used, and the reaction solution temperature was kept at 100°C. The transesterification reaction was carried out and evaluated in the same manner as in Example 1, except that the temperature was kept at 100° C. .

[0140] <Example 33> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount 1,4-cyclohexanedimethanol (S Igma-Aldrich; mixture of cis anthracene, purity ≥ 9 The reaction was carried out in the same manner as in Example 1, except that 9%) was used and the temperature of the reaction solution was kept at 100°C. The transesterification reaction was carried out and evaluated.

[0141] <Example 34> Instead of using ethylene glycol as a reactant in Example 1, the same molar amount (12 times the molar ratio of DMT units) of 2-ethyl-1-hexanol (Sigma a-Aldrich (purity ≥ 99.6%) was used, and the reaction temperature was maintained at 100°C. The transesterification reaction was carried out and evaluated in the same manner as in Example 1, except that the above-mentioned procedure was repeated.

[0142] [Comparison of transesterification reaction characteristics depending on the amount of catalyst used] Table 1 shows the results of the transesterification reaction in the examples 1 to 6 and Comparative Example 1. Accordingly, potassium carbonate (K 2 CO 3 ) to adjust the amount of reaction The results are shown in Fig. 1 (reaction temperature: 80°C, GHSV=240h) -1 ) Example using a catalyst Unlike Comparative Example 1, in which no catalyst was added, B after 2 hours and 8 hours The yields of HET were about 0.0% and 2.4%, respectively, and the kinetics of the transesterification reaction This is because the ethylene glycol of DMT at low temperatures, which is exemplified in the present invention, is very low. It is essential to use a catalyst to promote the addition transesterification of glycol. The results are clear.

[0143] [Table 1] DMT: dimethyl terephthalate, EG: ethylene glycol BHET: Bis(2-hydroxyethyl) terephthalate HEMT: 1-(2-hydroxyethyl)-4-methyl terephthalate K 2 -TPA: Dipotassium terephthalate K-MMT: Potassium monomethyl terephthalate

[0144] In Examples 1 to 4, the catalyst was used in an amount of 0.0001 to 0.01 mole per mole of DMT in the raw material 1. The reaction was carried out using potassium carbonate equivalent to the moles of potassium carbonate, and the amount of potassium carbonate increased. This shows that the production rate and yield of BHET are greatly improved as the temperature increases.

[0145] On the other hand, in Examples 5 and 6, the catalyst was used at 0.05 mole per mole of DMT, respectively. and 0.2 moles of potassium carbonate were used, but the rate of BHET formation was rather The degree and yield of the reaction tended to decrease. 2 -TPA The final yields tended to increase to 6.0% and 18.5%, respectively. If an excess of catalyst is used compared to the mole number of DMT, not only will the catalyst be consumed, but hydrolysis and This result explains that side reactions such as alkaline decomposition can be promoted. Proper adjustments help improve the performance and economics of the transesterification reaction. can be done.

[0146] [Comparison of transesterification reaction characteristics based on gas hourly space velocity (GHSV)] When DMT is transesterified in the presence of excess ethylene glycol, During the reaction, the rate of formation of the product BHET was observed to be extremely high, and the by-product BHET was generated by the exchange reaction. The rate of methanol formation also increases proportionally to the number of moles of BHET formed. In this transesterification reaction, all of the DMT initially charged is converted to BHET. This is not an irreversible reaction, but a reverse transesterification reaction in which the by-product methanol and BHET participate. When the forward and reverse reactions reach equilibrium, the rate of reaction no longer depends on the concentration of the compound. No change occurs and there may be limitations to improving the yield of the product by changing the reaction conditions. However, it is possible to effectively remove a portion of the reaction product in the reaction mixture or to remove it from the reaction system. When the substance is discharged to the outside, the reverse reaction can be suppressed. The reaction characteristics are the change in concentration of the substance, That is, it can be determined by the rate of mass transfer to the outside.

[0147] The methanol produced from the transesterification reaction carried out according to one embodiment of the present invention is The substance with the lowest boiling point among the raw materials and products to be used (130°C or more lower than ethylene glycol) In addition to increasing the temperature or reducing the pressure of the reaction system, a carrier gas can be introduced from the outside. Continuous gas flow leads to selective external release of methanol, which is then converted into methanol by the reverse transesterification reaction. It can inhibit the regeneration of DMT, which is involved in the production of acetylcholine.

[0148] [Table 2]

[0149] Table 2 shows the results of gas-liquid contact with the internal reactants of the reactor to remove methanol from the reaction product. The flow rate of the inert carrier gas (high purity nitrogen) was varied to induce The characteristics of the transesterification reaction were observed (reaction temperature: 80°C).

[0150] In the absence of carrier gas flow (Comparative Example 2), the transesterification reaction was carried out at 80°C for 3 hours. As a result, the yield of BHET was relatively low at about 58.4%. Despite being exposed to the reaction conditions for such a long time, the reaction yield only increased by a small amount, about 0.9%. The reactor was in the form of an open system, and the internal temperature was maintained above the boiling point of methanol. Even if the reaction is continued, some of the transesterification reaction will proceed and the methanol produced will be The reactants diffuse predominantly into the headspace or outside the reactor. This can be expected as a result of its presence in high concentrations in the reaction.

[0151] On the other hand, the transesterification was carried out under continuous flow conditions with different flow rates of nitrogen as a carrier gas. In the case of the conversion reaction (Example 1 and Examples 7 to 9), the conversion rate and the yield of BHET were greatly improved. In particular, it can be seen that the GHSV exceeds 200 in Examples 1 and 9. In the reaction, a BHET yield of 92% or more was obtained when the reaction time exceeded 3 hours. You can see that.

[0152] On the other hand, if the flow rate of the carrier gas is kept too high and the reaction conditions are maintained for a long time, dimers and It was found that the yield of BHET was not improved by the small increase in the yield of olefins and oligomers. In the case of Example 1, even when the reaction was carried out for 3 hours or more, no oligomers were observed in the reaction product. In contrast, when the transesterification reaction was carried out according to Example 9, the After this period, the selectivity for BHET decreased as oligomers began to form. Even though only a small amount of oligomers (<3%) was produced, the viscosity of the reaction mixture increased significantly. In both cases, a phenomenon was observed in which a part of the product formed a heterogeneous phase, causing the reactants to suddenly become suspended. Therefore, in order to maximize the yield of the polymer depolymerization monomer BHET, the carrier gas must be used. However, the methanol produced from the transesterification reaction can be efficiently removed. However, the addition reaction of ethylene glycol can also occur predominantly as a carrier gas. It is preferable to select the optimal flow conditions to improve the final yield of BHET.

[0153] [Changes in transesterification reaction characteristics due to reaction temperature] Table 3 shows the transesterification of DMT by ethylene glycol addition according to the method of the present invention. The reaction was carried out at different temperatures. The results are shown below (GHSV=2 40h -1 ).

[0154] When the temperature is maintained above the boiling point of methanol (Example 1 and Examples 12 to 16), The yield of BHET obtained from the ester exchange reaction was maintained high from the initial stage of the reaction, and the reaction time was It can be seen that a BHET yield of 95% or more can be obtained when the reaction time exceeds 4 hours. The improvement in the reaction temperature is due to the increase in the mass transfer rate of methanol when the reaction temperature exceeds the boiling point of methanol. At the same time, DMT is converted to HEMT and HEMT is converted to BHET. It can be assumed that this also contributed to the enhancement of the rate of the cis-catalyzed reaction.

[0155] [Table 3]

[0156] On the other hand, when the transesterification reaction was carried out while maintaining the reaction temperature below the boiling point of methanol, (Examples 10 and 11) The yield of BHET depending on the reaction time was After 2 hours, the rates were 45.4% and 73.9%, and after 4 hours, the rates were 68.1% and 86. It was observed to increase at a slightly slower rate of .8%.

[0157] Although not shown in the table, exposure to reaction conditions for a long period of time (after 7 hours of reaction time) As a result, oligomers began to be detected, and the DM applied after 8 hours of reaction Approximately 11.2% and 3.3% of the raw material T were converted to oligomers. It was also observed that the amount of the suspension significantly increased and changed to a non-uniform suspension.

[0158] In summary, the conversion rate of DMT can be increased within a short reaction time or residence time, and oligomer formation can be prevented. In order to improve the yield of the monomer BHET, the reaction temperature must be set at a temperature above the boiling point of methanol. It has been found that it is more advantageous to control the temperature above

[0159] [Comparison of transesterification reaction characteristics by selecting reaction catalyst] The existing glycolysis reactions for producing BHET from polymers containing ester functional groups are Since the process is carried out at high temperatures, it is pointed out that a large amount of energy is consumed. To overcome this problem, a new reaction pathway capable of producing BHET in high yields at low temperatures has been developed. It is possible.

[0160] One example of such a reaction pathway is the production of DMT from polymeric raw materials containing ester functional groups. The methanolysis reaction can be carried out at room temperature, and the ethylene glycol addition can be carried out continuously. If the predominantly low-temperature reaction conditions could be provided, a high yield of BHET could be produced. It can be expected that this will be possible.

[0161] If a separate separation step is not carried out after the first reaction, methanolysis, the reaction mixture produced will Although some catalyst may remain in the mixture, it exhibits sufficient performance for successive transesterification reactions. It may be necessary to design or consider new catalyst systems that can achieve this.

[0162] Catalysts commonly used in transesterification reactions include acidic, basic and metal salt catalysts. Acidic catalysts react more slowly than basic catalysts, so they react at high temperatures (over 100°C). In order to prevent corrosion, it is common to carry out acid resistance tests on the reactor and auxiliary equipment. Design is required, which can result in excessive initial capital costs.

[0163] Therefore, in the present invention, the ethylene glycol addition transesterification reaction of DMT is Evaluation of reaction performance against base catalysts and metal salt catalysts, which are expected to have reactivity and selectivity. The value and usefulness of the drug were examined.

[0164] To compare the relative performance of the catalysts, the reaction conditions were the same except for the type of catalyst, i.e. The amount of the Stell reaction catalyst was 0.001 mole per mole of DMT, and the carrier gas flow rate was This is GHSV240h -1 The reaction temperature was maintained at 80° C. and the reaction was carried out for 3 hours.

[0165] As a catalyst for performance evaluation, it is expected to show the best performance in transesterification reactions. Metal acetates (e.g. zinc acetate), alkali carbonates, alkali hydroxides, alkali alkalates, etc. Koxides, alkaline earth metal oxides, and guanidine-based organic compounds were selected for use. The reaction performance and the acid dissociation equilibrium constant (pKa) are shown in Table 4 (reaction temperature: 80°C, reaction Time 3h, GHSV=240h -1 )

[0166] [Table 4] DMT: dimethyl terephthalate, EG: ethylene glycol BHET: Bis(2-hydroxyethyl) terephthalate HEMT: 1-(2-hydroxyethyl)-4-methyl terephthalate KOAc: Potassium acetate, Sodium acetate, Zinc diacetate, Zinc acetate dihydrate TBD: Triazabicyclodecene K 2 -TPA: Dipotassium terephthalate K-MMT: Potassium monomethyl terephthalate

[0167] A general high-temperature method for producing BHET by depolymerization of polymers containing ester functional groups. In the reaction process, metal acetates are used as catalysts. In particular, zinc acetate (Zn(CH 3 CO O) 2 2H 2 O) has high polymer depolymerization reactivity and excellent selectivity for BHET. Therefore, it is the most commonly used commercial process. To confirm the catalytic effectiveness of the acid metal salts, potassium acetate, sodium acetate, and zinc acetate were used. After adding the above as a substitute catalyst, a reaction experiment was carried out.

[0168] Under the same conditions, potassium acetate and sodium acetate were added as alternative catalysts, and the reaction was then carried out. In the case of Comparative Examples 3 and 4, the BHET yield was at a level of 4% or less after 3 hours. Low reaction performance was always observed. In addition, in the case of Comparative Example 5 in which zinc acetate was used as a catalyst, The yield of BHET was 0.7%, and the yield of BHET was 0.7%, similar to that of Comparative Example 1, which was carried out without adding a catalyst. Almost no ET was produced. Therefore, the existing high-temperature (≧190°C) glycolysis Metal acetates that can be usefully used in the reaction are those that are suitable for the transesterification reaction carried out according to the present invention. It was found that the cations of the cations in ...

[0169] In Examples 3 and 17 to 19, a metal salt catalyst in which carbonic acid and bicarbonate were used as an anion was used. Comparing the reaction results, potassium carbonate (K 2 CO 3 ) and sodium carbonate (Na 2 CO 3 ) was used as a catalyst and the reaction was carried out for 3 hours, the yield of BHET was 92.0 and 93.0%, respectively. % and 92.3%, and potassium bicarbonate (KHCO 3 ) and sodium bicarbonate (NaH CO 3 The BHET yield was 13% higher than that when CrN 2 ) was used as a catalyst.

[0170] Alkali hydroxides (or alkali metal hydroxide salts) are useful for the dissolution of polymers containing ester functional groups. It is used as a typical raw material for alkaline decomposition reaction during polymerization reaction. In alkaline decomposition reaction, Since alkali hydroxides directly participate as reactants in the decomposition of ester bonds, the polymer is maintained. The number of moles of ester bond groups is in excess of the number of moles of ester bond groups, and water, alcohol, etc. are supplied for the reaction. and ethylene glycol is discharged as a reaction product.

[0171] In this specification, the alkali hydroxide is used as a catalyst rather than a reactant for alkali decomposition. The reaction conditions according to the present specification, i.e., ethylene glycol was supplied in excess, A small amount of alkaline hydroxide is generated in the temperature range between room temperature (25°C) and the boiling point of ethylene glycol. Adding hydroxide can act as a catalyst for transesterification. Sodium and sodium hydroxide (Examples 20 and 21) were added at 0.001 mole per mole of DMT. As a result of the transesterification reaction using a small amount of DMT, all of the DMT was converted and the reaction proceeded in 3 hours. The yield of BHET after the reaction reached a value of more than 91%.

[0172] Next, when metal alkoxide salts were used as alternative catalysts, the The performance was confirmed. Potassium methoxide (CH 3 OK) or sodium methoxide (CH 3 When ONa) was used as an alternative catalyst (Examples 22 and 23), high reactivity and In both cases, the BHET yields after 3 hours of reaction were relatively high, at 90.6% and 83.6%, respectively. These catalysts were previously used in the case of applying an alkali metal carbonate catalyst (Example 3 and Example 18), the first ethylene glycol addition reaction from DMT (HEMT This is effective in increasing the rate of the first addition reaction (formation of 1,2-dihydro-2,4-triphenylphosphine), but not in the second addition reaction (formation of BHET). and showed low reaction rate characteristics.

[0173] Even when alkaline earth metal oxide catalysts were used, the performance of the transesterification reaction was high and The reaction was carried out using magnesium oxide and calcium oxide as alternative catalysts. (Examples 24 and 25) The conversion rate was observed to be 96% or more, and the BHE after 3 hours of reaction The T yields were 77.4% and 90.6%, respectively.

[0174] Finally, the reaction characteristics of metal-free organic catalysts were compared. is a guanidine-based cation exchange catalyst that has strong base properties and is commonly used as an organic synthesis catalyst. The compound triazabicyclodecene (TBD) is used as a catalyst for the transesterification reaction. Potassium carbonate (K 2 CO 3 As in Example 3, the reaction was carried out using 1,2-dichlorophenyl ether as a catalyst. Almost all of the DMT added after 3 hours participated in the glycolysis reaction, and BHET was obtained. The observed rate was relatively high at 90.5%.

[0175] Comparing the reaction performance based on the acid dissociation equilibrium constant (pKa) of the catalysts used above in Table 4, To obtain a high yield of BHET by carrying out the low-temperature (≦100° C.) glycolysis reaction of the present invention It has been confirmed that a catalyst with a pKa value of 6 or more is suitable.

[0176] [Production of BHET by transesterification of polymers containing ester functional groups] Glycosylation for the direct production of BHET by depolymerization of polymeric raw materials containing ester functional groups The reaction is generally carried out at high temperatures of 190 to 300°C. As reported, the high-temperature glycolysis reaction was carried out by applying metal acetate as a catalyst, and the addition reaction The reaction is generally carried out at or above the boiling point of the reactant, ethylene glycol. In this catalytic reaction, the monomer product (BHET) by glycolysis accounts for 80% or more. It is obtained in a higher proportion than other compounds, but is produced through side reactions such as hydrolysis. By-products (e.g., monohydroxyethyl terephthalate (MHET), terephthalic acid) In addition, it was observed that dimers and oligomers were produced in a certain proportion depending on the reaction equilibrium. In contrast, one example of the present invention uses a different temperature range and BHET generation mechanism. When depolymerization was carried out using a low-temperature methanolysis-glycolysis tandem reaction pathway, High yield of high purity BHET containing only intermediates (e.g., HEMT) and dimers can be obtained.

[0177] Table 5 shows the results of high temperature (190°C) and low temperature ester interchange produced using the same raw material 2. Conversion reaction (methanolysis at 25°C and ethylene glycol addition transesterification at 80°C) The results are shown in comparison.

[0178] In the table below, the moles of EG and catalyst in Comparative Example 6 are based on the repeating unit of PET. The moles of EG and catalyst in Example 27 are based on DMT.

[0179] [Table 5]

[0180] When the depolymerization reaction was carried out at high temperature using zinc acetate (Comparative Example 6), the initial reaction time (within 2 hours) was ) polymer decomposition occurred at a rapid rate, and the yield of BHET was 80.6%. However, when this was exposed to the reaction conditions for a long time, such as 8 hours, the increase in the yield of BHET was not noticeable. The yield of monomers was about 4.1%, and that of oligomers was 10–15%, with a high concentration of undegraded compounds. It was observed that

[0181] In Example 27, the PET raw material (raw material 2) used previously was used in the same manner, and a co-solvent was applied. The liquid reaction mixture obtained by the methanolysis-based depolymerization at room temperature (25°C) (yield of DMT) After removing part of the catalyst by filtration and removing the solvent by increasing the temperature, Then, ethylene glycol was added to carry out the second reaction, glycolysis. In this case, reaction characteristics and product distributions very different from those of the high-temperature glycolysis in Comparative Example 6 were observed. Ta.

[0182] In Example 27, a very high DMT conversion rate was observed from the early stage of the reaction, and sufficient A BHET yield of over 92% was observed when the reaction was left under the reaction conditions for a period of time (8 hours or more). Looking at the distribution of reaction by-products, MHET was the reaction by-product in the high-temperature glycolysis of Comparative Example 6. In Example 27, only one ethylene glycol addition reaction was carried out. T is obtained as a reaction intermediate, and the reaction proceeds relatively quickly, with less than 0.5% after 8 hours of reaction. Only very low concentrations of HEMT were observed to remain.

[0183] These results suggest that the ester functional group can be catalyzed via a low-temperature methanolysis-glycolysis reaction. The same catalyst can be used for each reaction in succession to produce BHET from polymers containing It can be confirmed that:

[0184] [Comparison of transesterification reaction characteristics and monomer product yields by type of alcohol reactant] Table 6 shows the raw materials for the glycolysis reaction in the production of polymeric monomers containing ester functional groups. Instead of ethylene glycol, different types of monohydric or polyhydric alcohols are added. The results of observing the characteristics of the ester exchange reaction carried out at a reaction temperature of 100 ℃, GHSV=240h -1 ).

[0185] [Table 6] DMT: Dimethyl terephthalate, K 2 -TPA: Dipotassium terephthalate K-MMT: Potassium monomethyl terephthalate EG: ethylene glycol, PDO: propanediol, BDO: butanediol, HDO: hexanediol, CHEM: 1,4-cyclohexanedimethanol, 2E1H: 2-ethyl-1-hexanol Monomer product: Both methyl groups of DMT are completely replaced by diol reactants Intermediate: Only one methyl group of DMT is replaced by transesterification

[0186] As addition reactants, chain diols (Examples 12 and 28 to 32) and cyclic diols ( As a result of carrying out an ester exchange reaction using the ester of Example 33), as the carbon number increases, the DM The initial conversion rate of T was observed to be somewhat slower as the molecular size of the diol increased. As the number of carbon atoms increases, steric hindrance can occur, and as the number of carbon atoms increases, This can be expected as a result of the lower reactivity for the cyclohexane exchange reaction. ,3-propanediol was used as a reactant in the transesterification reaction (Example 28) , 1-(3-hydroxypropyl) 4-methyl terephthalate, of which DMT is a reaction intermediate The rate of the first transesterification reaction, in which 1,4-butanediol is converted to ester (HBMT), is It was observed that the reaction was faster than that when it was applied as a reactant in the ester exchange reaction (Example 29). However, the reaction intermediate is converted into the product, bis-(3-hydroxypropyl) terephthalate (BH The rate of secondary transesterification, which converts ethylenediaminetetraacetate (EPT) to ethylenediaminetetraacetate (PT), was observed to be relatively slow. The structural characteristics of the diol compound substituted by the transesterification reaction are then determined as secondary esters. This explains the effect that the exchange reaction has on the rate of

[0187] On the other hand, the transesterification reaction can be carried out using α,ω-diols at both ends of the chain. Instead of the 1,3-propanediol (Example 28), which has a second alcohol functionality adjacent Structural isomers that are expected to be in close proximity and have a direct effect on the transesterification reaction When 1,2-propanediol was used as a reactant (Example 31), primary and secondary It was observed that the transesterification rates were all significantly limited. The results of the transesterification reaction using a structural isomer of butanediol having the following structure as a reactant (Example 2 9 and Example 32), the rate of the primary and secondary transesterification reactions was increased due to the flexibility of the chain. It was observed that the cyclic hydrocarbon structure had a relatively large volume. When 1,4-cyclohexanedimethanol containing 3) The transesterification reaction proceeded slowly due to the steric hindrance of the diol molecular structure itself. On the other hand, in the early stage of the reaction, it was observed that only the primary transesterification reaction proceeded selectively. This is a mono- or polyhydric alcohol that is applied to the primary and secondary transesterification reactions. When different types of reactants are used, monomer structures with different ester bond pairs are obtained. This result shows that it is possible to design a

[0188] Using 2-ethylhexanol, the main raw material for plasticizers, as the additive reactant, When the transesterification reaction was carried out (Example 34), the conversion rate of DMT progressed rapidly from the initial stage of the reaction. Most of the DMT was converted within 2 hours of incubation. Despite exposure to these conditions, dioctyl terephthalate was obtained as a monomer product without the formation of any by-products. The rate (DOTP) remained stable.

[0189] In summary, the present invention provides an example of an ester that can be produced by adding different types of alcohol. When the conditions for the ester exchange reaction were applied, functional groups of various structures were linked to terephthalic acid via ester bonds. It is possible to prepare the monomer in a form bound to a carboxylate.

[0190] Although the specific parts of the present invention have been described in detail above, it is understood that those skilled in the art will be able to easily understand the present invention. It is to be understood by those skilled in the art that these specific techniques are merely preferred embodiments, It is clear that the scope of the present invention is not limited to the above. It is intended that the full scope of the present invention be defined by the appended claims and their equivalents.

Claims

1. A method for producing a terephthalate derivative from dimethyl terephthalate, comprising the steps of: (a) Dimethyl terephthalate is mixed with monohydric and / or polyhydric alcohols for transesterification. The reactants are alkali carbonates, alkali hydroxides, alkali alkoxides, and alkali salts. At least one selected from the group consisting of alkaline earth metal oxides and guanidine-based organic compounds In the presence of one transesterification catalyst, an ester is reacted with a carrier gas in a stream. performing an exchange reaction; (b) isolating and obtaining the terephthalate derivative produced in the reaction. A method for producing a terephthalate derivative from dimethyl terephthalate, comprising the steps of:

2. The transesterification catalyst is 0.5 mole per mole of dimethyl terephthalate in step (a). The terephthalic acid according to claim 1, characterized in that the molar ratio is in the range of 0.0005 to 1.0 mol. A method for producing terephthalate derivatives from dimethyl.

3. The alcohol in step (a) is ethylene glycol. A method for producing a terephthalate derivative from the dimethyl terephthalate according to claim 1.

4. Method for producing terephthalate derivatives by depolymerization of polymers containing ester functional groups There was, (A) A polymer containing an ester functional group is mixed with an alcohol, a polar aprotic solvent, and potassium carbonate. Um (K ２ CO ３ ) to depolymerize; (B) A carrier gas flow is applied to the depolymerization result obtained in step (A), carrying out a transesterification reaction; (C) a step of separating and obtaining the terephthalate derivative produced in the reaction. The present invention relates to a method for producing a terephthalate derivative by depolymerization of a polymer containing an ester functional group. How to make it.

5. After the step (A), a step of separating a part of the compound from the depolymerization resultant to the outside may be further performed. The depolymerization of the polymer containing ester functional groups according to claim 4, A method for producing a terephthalate derivative.

6. The part of the compounds separated from the outside is a polymer containing unreacted ester functional groups, an insoluble The present invention includes at least one selected from the group consisting of a catalyst, a polar aprotic solvent, and a reaction by-product. The depolymerization of the polymer containing the ester functional group according to claim 5 produces a terephthalate. A method for producing a phthalate derivative.

7. The polar aprotic solvent in step (A) is a solvent that is suitable for the depolymerization reaction of the polymer containing an ester functional group. Solvents that are inert and do not participate in the The organic compound has a skeleton structure that is a chain and / or a cyclic compound. The compound is characterized in that at least one of halogen elements, oxygen, and nitrogen is bonded to the compound. terephthalate by depolymerization of the polymer containing ester functional groups according to claim 4. Methods for producing derivatives.

8. The polar aprotic solvent in step (A) is toluene, xylene, acetone, methyl ether, Chirketone, methyl isobutyl ketone, acetonitrile, propionitrile, aminopropionitrile Propionitrile, methylaminopropionitrile, iminodipropionitrile, butyronitrile Butanenitrile, Methyl Ethyl Ether, Diethyl Acetone ter, ethyl phenyl ether, dimethoxybenzene, trimethoxybenzene, methoxy Phenol, tetrahydrofuran, methyltetrahydrofuran, dioxane, chloromethan dichloromethane, chloroform, tetrachloromethane, chlorobenzene, dichlorobenzene At least one selected from the group consisting of benzene, trichlorobenzene, and trichlorobenzene. The depolymerization of the polymer containing the ester functional group according to claim 4 produces a terephthalate derivative. A method for manufacturing a conductor.

9. In the step (A), the number of moles of the repeating unit of the polymer raw material containing an ester functional group is The number of moles of the alcohol and the number of moles of the polar aprotic solvent are determined based on the ester group. The ratio of the number of moles of the repeating unit of the polymer raw material containing the functional group is 0.1 to 5,000 times. The depolymerization of the polymer containing ester functional groups according to claim 4 is characterized in that A method for producing a terephthalate derivative.

10. Before the transesterification reaction in step (B), an ester is added to the depolymerization product in step (A). Monohydric and / or polyhydric alcohol reactants and / or alkali as reactants for alcohol exchange Carbonates, alkali hydroxides, alkali alkoxides, alkaline earth metal oxides and guanidine At least one ene selected from the group consisting of guanidine-based organic compounds. The ester exchange reaction catalyst is added in a predetermined amount per mole of dimethyl terephthalate contained in the depolymerization product. The ester functional group according to claim 4, characterized in that the number of moles is adjusted to be in the range. A method for producing a terephthalate derivative by depolymerization of a polymer comprising:

11. The methanol recovered in step (C) is reused as the depolymerization raw material in step (A). The depolymerization of the polymer containing ester functional groups according to claim 4 is carried out. A method for producing a terephthalate derivative by

12. The catalyst for transesterification prepared in the step (B) is selected from the terephthalic acid and tert-butyl ethers contained in the depolymerization product. The molar ratio is 0.00005 to 1.0 times per mole of dimethyl phthalate. The depolymerization of the polymer containing the ester functional group according to claim 4 produces a terephthalate derivative. A method for manufacturing a conductor.

Images