Recycled terephthalic acid and polyester resin comprising same

Abstract

The present invention relates to a recycled terephthalic acid produced from waste polyester and a polyester resin comprising same. Specifically, according to an embodiment of the present invention, the recycled terephthalic acid is obtained by alcoholysis and hydrolysis of waste polyester, and color b measured in a reflection mode of a spectrophotometer satisfies less than 2, and thus the recycled terephthalic acid is environmentally friendly, has a low pigment residual rate and a low yellow index, and also has a very low content of metal, which is an impurity. Therefore, the polyester resin comprising the recycled terephthalic acid has excellent quality without further comprising a terephthalic acid in addition to the recycled terephthalic acid.

Description

Regenerated terephthalic acid and polyester resin containing the same

[0001] The present invention relates to recycled terephthalic acid produced from waste polyester and a polyester resin containing the same.

[0002] Polyester boasts excellent mechanical strength, heat resistance, transparency, and gas barrier properties, making it widely used in beverage containers, packaging films, audio and video films, and industrial materials such as medical fibers and tire cords. In particular, polyester sheets and boards, with their excellent transparency and mechanical strength, are widely used in cases, boxes, partitions, shelves, panels, packaging, building materials, and interior and exterior finishes.

[0003] As the annual global volume of polyester-based plastic waste grows to unmanageable levels, interest in recycling waste polyester or regeneration processes utilizing it is growing. Furthermore, countries around the world are developing regulations and measures for recycling waste plastic resources, including waste polyester. For example, regulations requiring a certain percentage of recycled resin in packaging materials used in various fields are being discussed.

[0004] In particular, polyethylene terephthalate (PET) is widely used in the manufacture of a wide range of products such as films, fibers, bottles, and containers due to its excellent properties such as heat resistance, processability, transparency, and non-toxicity. However, most of it is landfilled or incinerated after use, and research on recycling or regeneration processes using it is ongoing.

[0005] For example, Korean Patent Laid-Open Publication No. 1997-0042469 discloses a technology for producing terephthalic acid by hydrolyzing waste polyethylene terephthalate with an alkaline aqueous solution to produce a slurry of terephthalic acid alkali metal and earth metal salts, and neutralizing it with an acid. However, since a terephthalic acid salt, not terephthalic acid, is produced as a result of the hydrolysis reaction, a neutralization step of adding acid is required to convert it to terephthalic acid, and there is a problem that the resulting byproducts generate environmental pollutants or a large amount of acid treatment waste. In addition, in the case of terephthalic acid converted from a terephthalic acid salt, it is not easy to remove impurities, so the purity is low and the physical properties, such as color characteristics, are poor, resulting in low quality.

[0006] [Prior Art Literature]

[0007] [Patent Document]

[0008] (Patent Document 1) Korean Patent Publication No. 1997-0042469

[0009] Accordingly, the present invention aims to provide a recycled terephthalic acid of excellent quality obtained in an environmentally friendly manner by alcoholysis and hydrolysis of waste polyester, and a polyester resin containing the same.

[0010] According to one embodiment of the present invention, the recycled terephthalic acid is obtained by alcoholysis and hydrolysis of waste polyester, and has a Color b of less than 2 measured in the reflection mode of a spectrophotometer.

[0011] According to another embodiment of the present invention, a polyester resin is obtained by alcoholysis and hydrolysis of waste polyester, and includes recycled terephthalic acid having a Color b of less than 2 as measured in a reflection mode of a spectrophotometer, and a difference between the Color L value and the Color b value (Color L - Color b) measured in a transmission mode of a spectrophotometer for a 6 mm thick specimen is greater than 83.

[0012] An article according to another embodiment of the present invention comprises the polyester resin.

[0013] A method for producing a polyester resin according to another embodiment of the present invention comprises the steps of producing recycled terephthalic acid by alcoholysis and hydrolysis of waste polyester; producing a preliminary composition by mixing the recycled terephthalic acid with a glycol component; subjecting the preliminary composition to an esterification reaction; and subjecting the esterification reaction product to a polycondensation reaction, wherein the recycled terephthalic acid has a Color b value of less than 2.

[0014] According to one embodiment of the present invention, the recycled terephthalic acid is obtained by alcoholysis and hydrolysis of waste polyester, and is environmentally friendly as it satisfies the Color b of less than 2 as measured in the reflection mode of a spectrophotometer, and has a low pigment residue rate and yellowness, and also has a very low content of metal impurities, so it has excellent quality.

[0015] Therefore, the polyester resin containing the recycled terephthalic acid has excellent quality even without additional terephthalic acid in addition to the recycled terephthalic acid. Specifically, in the case of the recycled terephthalic acid conventionally manufactured from waste polyester, the physical properties such as color characteristics were not good. In addition, the quality of the polyester resin manufactured using only the recycled terephthalic acid as the acid component was also low, making it difficult to utilize. Therefore, in order to secure the physical properties of the polyester resin, the content of recycled terephthalic acid has been reduced and used in small amounts, or mixed with commercially available terephthalic acid.

[0016] However, the polyester resin according to one embodiment of the present invention is manufactured from waste polyester, and has a low pigment residue and yellowness, as well as a very low content of metal as an impurity, thereby including recycled terephthalic acid of excellent quality, so that it has excellent quality even when it contains recycled terephthalic acid alone as an acid component or contains recycled terephthalic acid in a higher content than before.

[0017] Hereinafter, the present invention will be described in detail. The present invention is not limited to the contents disclosed below and may be modified in various forms without changing the gist of the invention.

[0018] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0019] All numbers and expressions indicating the amounts of components, reaction conditions, etc. described in this specification should be understood to be modified by the term “about” in all cases unless otherwise specified.

[0020] In this specification, the terms "first," "second," etc. are used to describe various components, and the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0021]

[0022] Recycled terephthalic acid

[0023] According to one embodiment of the present invention, the recycled terephthalic acid is obtained by alcoholysis and hydrolysis of waste polyester, and has a Color b of less than 2 measured in the reflection mode of a spectrophotometer.

[0024] The above alcohololysis and hydrolysis will be described in detail below.

[0025] According to one embodiment of the present invention, the regenerated terephthalic acid has a Color b measured in a reflection mode of a spectrophotometer of less than 2. For example, the regenerated terephthalic acid may have a Color b measured in a reflection mode of a spectrophotometer of 1.9 or less, 1.8 or less, 1.6 or less, 1.4 or less, 1.2 or less, or 1 or less. Since the numerical range of the Color b is equivalent to that of general terephthalic acid produced in a petrochemical process, the Color b of the regenerated terephthalic acid satisfies the above range, so that not only is the yellowness low, but also the monomer is purified well, resulting in excellent quality.

[0026] The above Color b is a color system established by the International Standard Color Measurement Organization (CIE (Commission International d'Eclairage), and expresses color by indicating Color as L (brightness), a (complementary color from green to red), and b (complementary color from yellow to blue), and can be measured using a spectrophotometer.

[0027] More specifically, for the above-mentioned recycled terephthalic acid, a Varian Cary 5 UV / Vis / NIR spectrophotometer equipped with a diffuse reflectance accessory capable of measuring color and brightness was used, and data was obtained through reflectance mode with Illuminant D65 at an observer angle of 2°, and the Color b value was calculated by processing it with a color analysis device within the Grams / 32 software.

[0028] The above-mentioned regenerated terephthalic acid is obtained through a purification process and may have a pigment residue rate of 10% or less according to the following formula 1.

[0029] [Formula 1]

[0030]

[0031] In the above equation 1,

[0032] B1 is the area of ​​the absorbance curve obtained from 400 nm to 800 nm using a UV-vis spectrophotometer after diluting the above-mentioned regenerated terephthalic acid to a concentration of 5% in dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or methylpyrrolidone (NMP),

[0033] B2 is the area of ​​the absorbance curve obtained by the same method as above for regenerated terephthalic acid manufactured through the same process as the manufacturing process of the above-mentioned regenerated terephthalic acid, but without performing a purification process.

[0034] The above B1 may be measured for regenerated terephthalic acid manufactured by performing a purification process, or a purification and concentration process, in a process for manufacturing regenerated terephthalic acid, and the above B2 may be measured for regenerated terephthalic acid manufactured by performing only a concentration process or not performing a purification process in a process for manufacturing regenerated terephthalic acid.

[0035] The above pigment residue rate refers to the content of additives such as colorants, pigments, dyes, etc. remaining in the composition. The lower the value of this pigment residue rate, the lower the content of additives such as colorants, pigments, dyes, etc., and thus the higher the purity can be considered.

[0036] For example, the pigment residue of the above-mentioned recycled terephthalic acid may be 9% or less, 8% or less, 7% or less, 5% or less, or 4% or less.

[0037] As a specific example, when dimethyl sulfoxide (DMSO) is used as a solvent for diluting the regenerated terephthalic acid, the pigment residue rate according to the above formula 1 may be 2% or less, 1% or less, or 0.5% or less, when dimethylformamide (DMF) is used, the pigment residue rate according to the above formula 1 may be 2% or less, 1% or less, or 0.5% or less, and when methylpyrrolidone (NMP) is used, the pigment residue rate according to the above formula 1 may be 2% or less, 1% or less, or 0.5% or less.

[0038] The above purification and concentration processes are described in detail below.

[0039] In addition, the above-mentioned regenerated terephthalic acid may be diluted to a concentration of 5% using dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or methylpyrrolidone (NMP), and then the yellowness index (YI) measured using a colorimeter may be less than 2, 1.9 or less, 1.8 or less, or 1.7 or less.

[0040] As a specific example, the yellowness measured with a colorimeter after the regenerated terephthalic acid is diluted to a concentration of 5% using dimethyl sulfoxide (DMSO) may be 2 or less, 1.8 or less, or 1.6 or less, the yellowness measured with a colorimeter after the regenerated terephthalic acid is diluted to a concentration of 5% using dimethylformamide (DMF) may be 2 or less, 1.9 or less, or 1.6 or less, the yellowness measured with a colorimeter after the regenerated terephthalic acid is diluted to a concentration of 5% using methylpyrrolidone (NMP) may be 2 or less, 1.7 or less, or 1.6 or less.

[0041] The above yellowness may be measured for regenerated terephthalic acid manufactured by performing a purification or purification and concentration process in the process of manufacturing regenerated terephthalic acid.

[0042] According to one embodiment of the present invention, the regenerated terephthalic acid may have a total metal content of less than 100 ppm as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Specifically, the regenerated terephthalic acid, more specifically, regenerated terephthalic acid produced by performing a purification or purification and concentration process, may have a low content of insoluble impurities such as metals.

[0043] For example, the recycled terephthalic acid may have a total metal content of 90 ppm or less, 80 ppm or less, 65 ppm or less, 50 ppm or less, 35 ppm or less, less than 30 ppm, 15 ppm or less, 9 ppm or less, 7 ppm or less, 5 ppm or less, or 1 ppm or less as measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0044] Additionally, the recycled terephthalic acid may have a total content of Sb, Ti, and Zn of less than 30 ppm as measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). For example, the recycled terephthalic acid may have a total content of Sb, Ti, and Zn of 25 ppm or less, 20 ppm or less, 15 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, or 1 ppm or less, which are harmful to the human body or may be utilized as reaction or side reaction catalysts in a future polymerization process.

[0045] For example, the recycled terephthalic acid may have a Sb content measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) of 30 ppm or less, 25 ppm or less, 20 ppm or less, 15 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, or 1 ppm or less relative to the total weight of the recycled terephthalic acid.

[0046] The above-mentioned recycled terephthalic acid may have a Ti content measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) of 30 ppm or less, 25 ppm or less, 20 ppm or less, 15 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, or 1 ppm or less relative to the total weight of the above-mentioned recycled terephthalic acid.

[0047] The above-mentioned recycled terephthalic acid may have a Zn content measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) of 30 ppm or less, 25 ppm or less, 20 ppm or less, 15 ppm or less, 10 ppm or less, 5 ppm or less, 3 ppm or less, or 1 ppm or less relative to the total weight of the above-mentioned recycled terephthalic acid.

[0048]

[0049] polyester resin

[0050] According to another embodiment of the present invention, a polyester resin is obtained by alcoholysis and hydrolysis of waste polyester, and includes recycled terephthalic acid having a Color b of less than 2 as measured in a reflection mode of a spectrophotometer, and a difference between the Color L value and the Color b value (Color L - Color b) measured in a transmission mode of a spectrophotometer for a 6 mm thick specimen is greater than 83.

[0051] The above polyester resin includes the above recycled terephthalic acid.

[0052] Specifically, the content of the recycled terephthalic acid may be 0.1 wt% to 55 wt% based on the total weight of the polyester resin. For example, the content of the recycled terephthalic acid may be 0.5 wt% to 55 wt%, 1 wt% to 52 wt%, 1.5 wt% to 50 wt%, 2 wt% to 48 wt%, 3 wt% to 46 wt%, 3.5 wt% to 45 wt%, or 10 wt% to 50 wt% based on the total weight of the polyester resin.

[0053] In addition, the polyester resin may have a difference between the Color L value and the Color b value (Color L - Color b) measured in the transmission mode of a spectrophotometer for a 6 mm thick specimen of greater than 83, 84 or more, 85 or more, 88 or more, 89 or more, or 90 or more.

[0054] More specifically, a 6 mm thick specimen was manufactured using the polyester resin, and data was obtained through transmission mode with Illuminant D65 at an observer angle of 2° using a Varian Cary 5 UV / Vis / NIR spectrophotometer equipped with a diffuse reflection accessory capable of measuring color and brightness for the specimen, and the Hunter Color L, Color a, and Color b values ​​were calculated by processing the data with a color analysis device within the Grams / 32 software, and the Color Lb value, which is the difference between the Color L value and the Color b value, was calculated.

[0055] Additionally, the polyester resin may have an intrinsic viscosity (IV) of 0.5 dl / g to 1.3 dl / g. For example, the intrinsic viscosity (IV) of the polyester resin may be 0.5 dl / g to 1.2 dl / g, 0.55 dl / g to 1 dl / g, or 0.6 dl / g to 0.95 dl / g.

[0056] According to one embodiment of the present invention, the polyester resin may include a diacid component and a glycol component. Specifically, the polyester resin may include only the recycled terephthalic acid as the diacid component, and may include another diacid component together with the recycled terephthalic acid. More specifically, the polyester resin is a resin in which the diacid component and the glycol component are copolymerized, and may include repeating units derived from the diacid component and repeating units derived from the glycol component.

[0057] Conventionally, recycled terephthalic acid manufactured from waste polyester has poor physical properties such as color characteristics, making it difficult to use it alone as a raw material for polyester resin as an acid component. However, a polyester resin according to an embodiment of the present invention is manufactured using the recycled terephthalic acid, and thus can secure sufficient physical properties even if the content of recycled terephthalic acid is increased compared to the conventional method. Therefore, a polyester resin according to an embodiment of the present invention may contain the recycled terephthalic acid alone, or may contain it together with another acid component to improve physical properties, etc.

[0058] The above-mentioned diacid components are terephthalic acid (TPA), isophthalic acid (IPA), dimethyl isophthalate, bis(2-hydroxyethyl) terephthalate, reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), phthalic acid, dimethyl phthalate, phthalic anhydride, 2,6-naphthalene dicarboxylic acid, dimethyl 2,6-naphthalene dicarboxylate, diphenyl dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, dimethyl 1,4-cyclohexane dicarboxylate, dimethyl 1,3-cyclohexane dicarboxylate, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, fumaric acid, It may include at least one selected from the group consisting of adipic acid, glutaric acid, and azelaic acid.

[0059] In addition, the glycol component is isosorbide (ISB), regenerated isosorbide (r-ISB), ethylene glycol (EG), regenerated ethylene glycol (r-EG), 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, cyclohexanedimethanol (CHDM) and derivatives thereof, regenerated It may include at least one selected from the group consisting of cyclohexanedimethanol (r-CHDM), diethylene glycol (DEG), recycled diethylene glycol (r-DEG), neopentyl glycol (NPG), and recycled neopentyl glycol (r-NPG).

[0060] Specifically, the polyester resin may include the recycled terephthalic acid and the diacid component. At this time, the molar ratio of the recycled terephthalic acid and the diacid component may be 1:0.01 to 3.5, 1:0.02 to 3.3, 1:0.03 to 3.0, or 1:0.05 to 2.6.

[0061] According to one embodiment of the present invention, the polyester resin may further include one or more additives selected from the group consisting of a coloring agent, a crystallizing agent, an oxidation stabilizer, and a branching agent.

[0062] The above coloring agent is an additive for improving the color characteristics of the polyester resin. As long as the coloring agent does not impede the effects of the present invention, a commonly used coloring agent such as cobalt acetate or cobalt propionate can be used.

[0063] Specifically, the coloring agent may be cobalt acetate, cobalt propionate, anthraquionone-based compound, perinone-based compound, azo-based compound, methine-based compound, etc.

[0064] In addition, the polyester resin may contain the coloring agent in an amount of 0.1 ppm to 30 ppm based on the total weight of the polyester resin. For example, the coloring agent may be contained in an amount of 0.2 ppm to 30 ppm, 0.5 ppm to 25 ppm, 0.6 ppm to 23 ppm, or 0.8 ppm to 20 ppm based on the total weight of the polyester resin. By satisfying the content of the coloring agent in the above range, the color characteristics can be sufficiently improved without deteriorating the mechanical properties of the polyester resin.

[0065] The above crystallizer may include at least one selected from the group consisting of a crystal nucleating agent, an ultraviolet absorber, a polyolefin resin, a polyamide resin, and a polyalkylene resin.

[0066] In addition, the polyester resin may contain the crystallizer in an amount of 0.1 ppm to 10 ppm based on the total weight of the polyester resin. For example, the crystallizer may be contained in an amount of 0.2 ppm to 8 ppm, 0.5 ppm to 6 ppm, 1 ppm to 10 ppm, 2 ppm to 8 ppm, 3 ppm to 6 ppm, or 4 ppm to 6 ppm based on the total weight of the polyester resin. By satisfying the content of the crystallizer within the above range, heat resistance and impact strength can be improved.

[0067] The above oxidation stabilizer may include at least one selected from the group consisting of a hindered phenol-based oxidation stabilizer, a phosphite-based oxidation stabilizer, and a thioether-based oxidation stabilizer.

[0068] In addition, the polyester resin may contain the oxidation stabilizer in an amount of 50 ppm to 2,500 ppm based on the total weight of the polyester resin. For example, the oxidation stabilizer may be contained in an amount of 50 ppm to 2,300 ppm, 60 ppm to 2,200 ppm, 80 ppm to 2,100 ppm, 100 ppm to 2,000 ppm, or 100 ppm to 1,500 ppm based on the total weight of the polyester resin. By satisfying the content of the oxidation stabilizer within the above range, not only can a decrease in intrinsic viscosity that may occur during subsequent processing or other processes be effectively prevented, but also a decrease in physical properties such as impact strength can be prevented.

[0069] The above-mentioned branching agent may include at least one selected from the group consisting of trimellitic anhydride, trimellitic propane, and trimellitic acid.

[0070] In addition, the polyester resin may contain the branching agent in an amount of 100 ppm to 2,500 ppm based on the total weight of the polyester resin. For example, the branching agent may be contained in an amount of 200 ppm to 2,500 ppm, 300 ppm to 2,300 ppm, 500 ppm to 2,300 ppm, 1,000 ppm to 2,500 ppm, 1,500 ppm to 2,300 ppm, or 1,800 ppm to 2,100 ppm based on the total weight of the polyester resin. By satisfying the content of the branching agent within the above range, the intrinsic viscosity can be more effectively controlled within a specific range, and thus physical properties such as impact strength can be improved.

[0071]

[0072] article

[0073] An article according to another embodiment of the present invention comprises the polyester resin.

[0074] The above article can be obtained by molding a resin including the polyester resin using a molding method such as extrusion or injection, and can be a film (or sheet) or a component used in the fields of automobiles, electricity, electronics, etc.

[0075] In addition, the above-mentioned article may include labels, cap seals, or packaging materials for various containers such as plastic.

[0076]

[0077] Method for producing polyester resin

[0078] A method for producing a polyester resin according to another embodiment of the present invention comprises the steps of producing recycled terephthalic acid by alcoholysis and hydrolysis of waste polyester; producing a preliminary composition by mixing the recycled terephthalic acid with a glycol component; subjecting the preliminary composition to an esterification reaction; and subjecting the esterification reaction product to a polycondensation reaction, wherein the recycled terephthalic acid has a Color b value of less than 2.

[0079]

[0080] A step for producing recycled terephthalic acid by alcoholysis and hydrolysis of waste polyester.

[0081] A method for producing a polyester resin according to another embodiment of the present invention includes a step of producing recycled terephthalic acid by alcoholysis and hydrolysis of waste polyester.

[0082] Specifically, the step of producing the above-described recycled terephthalic acid may include: (1) a step of producing a liquid composition including a compound represented by the following chemical formula 1 by alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms; and (2) a step of hydrolyzing the liquid composition.

[0083] [Chemical Formula 1]

[0084]

[0085] In the above chemical formula 1,

[0086] R1 is alkyl having 4 or more carbon atoms.

[0087]

[0088] Alcohololysis stage (1)

[0089] A method for producing recycled terephthalic acid according to another embodiment of the present invention includes a step of producing a liquid composition comprising a compound represented by the following chemical formula 1 by alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms.

[0090] The above-mentioned waste polyester may be a waste polyester product that has been crushed or melted. For example, the waste polyester may be a polyester product that has been crushed and recovered and separated after use through consumption, or may be converted into pellet form (Post Consumer Recycled Material; PCR), or may be polyester waste such as defective products or scraps that may be generated in processes such as forming polyester films, fibers, containers, etc. (Post Industrial Recycled Material; PIR), but is not limited thereto.

[0091] Additionally, the carbon number of the alcohol may be 4 or more, 6 or more, 8 or more, 10 or more, or 12 or more, and may be 4 to 14, 4 to 13, 4 to 10, 4 to 8, 6 to 12, 8 to 14, or 8 to 13.

[0092] By performing alcoholysis of waste polyester using an alcohol having the above carbon number, alcoholysis can be performed at lower temperature and pressure than the conventional waste polyester manufacturing process conditions performed at high temperature and high pressure, and an intermediate, i.e., an alcoholysis reaction product, can be produced in a liquid phase. In addition, since the carbon number of the alcohol satisfies the above range, the speed of the alcoholysis reaction can be improved.

[0093] In addition, the boiling point of the alcohol may be 100°C to 290°C. For example, the boiling point of the alcohol may be 100°C to 280°C, 100°C to 260°C, 100°C to 230°C, 110°C to 190°C, or 180°C to 290°C. Since the boiling point of the alcohol satisfies the above range, ethylene glycol, a by-product generated from the alcoholysis, can be more easily removed or recovered in a subsequent process, thereby further improving the processability. In particular, since there is a recent trend of using various monomer materials in fields that use polyester as a raw material, it can also be easily applied to removing various dialcohol-type monomers used in waste polyester products, such as waste plastic products.

[0094] The weight ratio of the waste polyester and the alcohol may be 1:1 to 10. For example, the weight ratio of the waste polyester and the alcohol may be 1:1 to 8, 1:1 to 6, 1:1 to 4, 1:1 to 3.5, 1:1.1 to 3.3, 1:2 to 4, or 1:2 to 3.5.

[0095] Additionally, the alcoholysis reaction can be performed at a temperature of 160°C to 280°C and a pressure of 1 bar to 40 bar for 0.5 to 24 hours. For example, the alcoholysis reaction can be carried out at a temperature of 165°C to 280°C, 165°C to 270°C, 180°C to 270°C, 190°C to 250°C, 200°C to 265°C, 220°C to 265°C, 240°C to 260°C or 245°C to 260°C, and a pressure of 1 bar to 38 bar, 1 bar to 33 bar, 1 bar to 28 bar, 1 bar to 24 bar, 2 bar to 40 bar, 3 bar to 35 bar or 5 bar to 30 bar for 0.5 hour to 22 hours, 1 hour to 15 hours, 1.5 hours to 10 hours, 2 hours to 8 hours or 2 hours to 6 hours.

[0096] In step (1), an alcoholysis catalyst may be introduced. Specifically, the alcoholysis reaction can be carried out smoothly even in a non-catalytic manner without the use of an alcoholysis catalyst, making it environmentally friendly. In particular, when the content of insoluble metals in waste polyester is high, a non-catalytic reaction may be advantageous for the efficient treatment and removal of impurities. Furthermore, an alcoholysis catalyst may be introduced in step (1) from an energy perspective, which can enhance reactivity and thus processability.

[0097] The above alcohol decomposition catalyst may be a metal acetate salt, an alkali metal salt, or a hydroxy salt.

[0098] More specifically, the alcohol decomposition catalyst is Li + , Na + , K + or Cs + Alkali metal ions, Be 2+ , Mg 2+ , Ca 2+ or Ba 2+ Alkaline earth metal ions, NH4+ or NR 4+ Ammonium ion of (R is alkyl), and Zn 2+ One or more cations selected from the group consisting of; and OH - , OR - (R is alkyl), HCO3 - , CO3 2- , benzoate ion (C7H5O2 - ), may include at least one anion selected from the group consisting of 4-alkoxycarbonylbenzoate ion, acetate ion, and terephthalate ion. The R may be an alkyl having 1 to 10 carbon atoms or an alkyl having 1 to 5 carbon atoms.

[0099] For example, the above alcoholysis catalyst is Zn(OAC)2, Co(OAc)2, Mn(OAc)2, Mg(OAc)2, Ca(OAc)2, Ba(OAc)2, LiOAc, NaOAc, KOAc, Zn(OAC)2·2H2O, Co(OAc)2·4H2O, Pb(OAc)2, Mn(OAc)2·4H2O, Mg(OAc)2·4H2O, Pd(OAc)2, It may include at least one selected from the group consisting of Ti(OBu)4, Ti(OiPr)4, GeO2, Al(OiPr)3, Na2CO3, K2CO3, dibutyltin(IV) oxide, tin octoate, titanium phosphate, and terephthalic acid.

[0100] In addition, the amount of the alcoholysis catalyst to be added may be 10 ppm to 10,000 ppm relative to the total weight of the waste polyester. For example, the amount of the alcoholysis catalyst to be added may be 10 ppm to 9,000 ppm, 15 ppm to 8,000 ppm, 20 ppm to 6,000 ppm, 50 ppm to 3,500 ppm, 100 ppm to 1,500 ppm, 150 ppm to 1,000 ppm, 180 ppm to 500 ppm, or 200 ppm to 450 ppm relative to the total weight of the waste polyester.

[0101] According to one embodiment of the present invention, a liquid composition comprising a compound represented by the following chemical formula 1 is prepared through the alcoholysis. Specifically, the composition is liquid at room temperature, and the liquid composition is a composition produced through the alcoholysis reaction.

[0102] The above liquid composition may include a compound represented by the following chemical formula 1.

[0103] [Chemical Formula 1]

[0104]

[0105] In the above chemical formula 1,

[0106] R1 is alkyl having 4 or more carbon atoms.

[0107] Specifically, the R1 is butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, hexyl, 1-methylhexyl, 2-ethyl-1-hexyl, heptyl, n-heptyl, 1-methylheptyl, octyl, n-octyl, isooctyl, tert-octyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, It can be 5-methylhexyl, decanyl, undecanyl, dodecanyl, tridecanyl or tetradecanyl.

[0108] Specifically, the liquid composition may include unreacted alcohol and ethylene glycol (EG), which is a by-product. More specifically, the liquid composition may include the compound represented by the chemical formula 1, ethylene glycol (EG), which is a by-product produced by the alcoholysis reaction, unreacted alcohol, and oligomers.

[0109] For example, the liquid composition may include a compound represented by the following chemical formula 2, and the oligomer may include a compound represented by the following chemical formula 3.

[0110] [Chemical Formula 2]

[0111]

[0112] [Chemical Formula 3]

[0113]

[0114] In the above chemical formulas 2 and 3,

[0115] R1 is alkyl having 4 or more carbon atoms,

[0116] n is an integer greater than or equal to 1.

[0117]

[0118] According to one embodiment of the present invention, the liquid composition may include unreacted alcohol and ethylene glycol as a by-product, and the content of the compound represented by the chemical formula 1 in the liquid composition may be 70 mol% or more. For example, for the liquid composition prepared through the alcoholysis, the content of the compound represented by the chemical formula 1 in the liquid composition may be 72 mol% or more, 75 mol% or more, 80 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, 92 mol% or more, 92.5 mol% or more, 93 mol% or more, 95 mol% or more, 97 mol% or more, 99 mol% or more, or 99.5 mol% or more.

[0119] Additionally, the content of the oligomer in the liquid composition may be 15 mol% or less. For example, the content of the oligomer in the composition may be 11 mol% or less, 8.5 mol% or less, 7 mol% or less, 5 mol% or less, 3 mol% or less, 1 mol% or less, 0.8 mol% or less, 0.4 mol% or less, or 0.1 mol% or less.

[0120] According to another embodiment of the present invention, the step (1) may include a step of discharging unreacted alcohol and ethylene glycol as a by-product.

[0121] Specifically, alcohol is separated from the mixture of the discharged alcohol and ethylene glycol, and the separated alcohol can be recycled as a raw material for the alcoholysis. For example, ethylene glycol and unreacted alcohol (alcohol present in excess), which are byproducts produced through alcoholysis, can be discharged in real time in the form of a gaseous mixture during the alcoholysis reaction and separated by fractional distillation or layer separation, and / or alcohol and ethylene glycol can be separated by fractional distillation after the reaction is completed, and the separated alcohol can be reused by being fed back into the alcoholysis of step (1). At this time, the capacity and feeding rate of the alcohol fed for reuse can be the same as the capacity and feeding rate of the mixture of the discharged alcohol and ethylene glycol.

[0122] In addition, step (1) may include a step of recovering ethylene glycol, which is a by-product of the alcoholysis. Specifically, the ethylene glycol, which is a by-product of the alcoholysis, may be recovered by fractional distillation or layer separation of the mixture of the discharged alcohol and ethylene glycol, and may be recovered by fractional distillation or layer separation of the composition prepared in step (1).

[0123] For example, during the alcohol decomposition reaction, the unreacted alcohol and the by-product ethylene glycol can be discharged in real time in the form of a gaseous mixture, and ethylene glycol can be recovered by condensing the mixture using an external cooling device.

[0124] According to one embodiment of the present invention, not only can unreacted alcohol and ethylene glycol be separated through a simple process such as fractional distillation or layer separation, but the separated unreacted alcohol can be recycled as a raw material for the alcoholysis, and the recovered ethylene glycol can be utilized in another process, so the processability and process cost reduction effects are excellent.

[0125] The recovery rate of the ethylene glycol may be 65% or more. For example, the recovery rate of the ethylene glycol may be 70% or more, 76% or more, 85% or more, 90% or more, 93% or more, 95% or more, 97% or more, 98% or more, 99% or more, or 99.5% or more.

[0126]

[0127] Refining stage

[0128] A method for producing terephthalic acid according to another embodiment of the present invention may additionally include a step of purifying the liquid composition prior to the following step (2).

[0129] Specifically, the purifying step may include a step of introducing one or more adsorbents selected from the group consisting of activated carbon, silica gel, alumina, zeolite, and activated clay, or adsorbing through bed adsorption. More specifically, the adsorbent may be activated carbon or a mixture of activated carbon and silica gel, and for example, the adsorbent may be a mixture of activated carbon and silica gel in a weight ratio of 1:0.5 to 1.5 or 1:0.8 to 1.2, but is not limited thereto.

[0130] The amount of the adsorbent added may be 0.1 wt% to 20 wt% based on the total weight of the liquid composition. For example, the amount of the adsorbent added may be 0.1 wt% to 18 wt%, 0.1 wt% to 15 wt%, 0.1 wt% to 10 wt%, 0.1 wt% to 5 wt%, or 0.1 wt% to 2 wt% based on the total weight of the liquid composition.

[0131] By additionally performing a step of purifying the liquid composition using the above adsorbent, specifically using a specific adsorbent that satisfies the input amount within the above numerical range, the purity and yield can be further improved. Specifically, by performing a step of purifying the liquid composition which is the alcoholysis reaction composition, insoluble impurities such as metals that may be included in the alcoholysis reaction composition, or additives such as colorants and pigments that may be included in waste polyester, can be more effectively removed, thereby further improving the purity and yield of the terephthalic acid finally produced.

[0132] In addition, a method for producing terephthalic acid according to another embodiment of the present invention may additionally include a step of concentrating after the purification step.

[0133] The concentration may be performed at a temperature of 50°C to 120°C for 0.5 to 6 hours. For example, the concentration may be performed by stirring the purified alcoholysis reaction composition at a temperature of 55°C to 115°C, 60°C to 110°C, 65°C to 105°C, or 75°C to 100°C for 1 to 5 hours, 1.5 to 4 hours, or 2 to 4 hours.

[0134] In addition, the purified composition may have a pigment residue rate (%) of 15% or less according to the following formula A.

[0135] [Formula A]

[0136]

[0137] In the above formula A,

[0138] A1 is the area of ​​the absorbance curve obtained from 400 nm to 800 nm using a UV-vis spectrophotometer after diluting the purified alcoholysis reaction composition to a concentration of 5% using dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or methylpyrrolidone (NMP), respectively.

[0139] A2 is the area of ​​the absorbance curve obtained by the same method as above for the alcoholysis reaction composition prepared without purification.

[0140] For example, the pigment residue rate of the above-mentioned purified alcoholysis reaction composition may be 13% or less, 11% or less, 10% or less, 8% or less, 6% or less, 5.5% or less, 5% or less, 4.3% or less, or 4% or less, as determined by the following formula A.

[0141] As a specific example, when dimethyl sulfoxide (DMSO) is used as a solvent for diluting the purified alcoholysis reaction composition, the pigment residue rate according to the above formula A may be 11% or less, 10% or less, or 8.5% or less, when dimethylformamide (DMF) is used, the pigment residue rate according to the above formula 1 may be 10.5% or less, 9% or less, or 8.3% or less, and when methylpyrrolidone (NMP) is used, the pigment residue rate according to the above formula 1 may be 10% or less, 8.5% or less, or 8% or less.

[0142]

[0143] Hydrolysis reaction step (2)

[0144] A method for producing regenerated terephthalic acid according to one embodiment of the present invention includes a step of hydrolyzing the liquid composition. Specifically, step (2) may produce regenerated terephthalic acid by hydrolyzing the alcoholysis reaction composition (liquid composition comprising the compound represented by the chemical formula 1) or the purified alcoholysis reaction composition produced in step (1).

[0145] The hydrolysis may be performed by adding water to the composition. For example, the hydrolysis may be performed by adding water to the alcoholysis reaction composition or the purified alcoholysis reaction composition, and at a temperature of 180°C to 280°C, 185°C to 280°C, 200°C to 275°C, 220°C to 270°C, or 240°C to 265°C for 0.5 to 24 hours, 1 to 20 hours, 2.5 to 12 hours, or 3 to 8 hours.

[0146] Conventionally, a process of adding a metal catalyst such as iron, cobalt, manganese, or nickel to waste polyester and then directly hydrolyzing it with water is environmentally friendly. However, it requires extremely high temperatures of 300°C or higher, and the reaction apparatus must also have high pressure resistance, resulting in low processability. However, the method for producing recycled terephthalic acid according to one embodiment of the present invention exhibits superior processability due to relaxed process conditions compared to conventional methods, as described above.

[0147] Additionally, the weight ratio of the composition and the water may be 1:1 to 500. For example, the weight ratio of the alcoholysis reaction composition (purified, or purified and concentrated alcoholysis reaction composition) used for the hydrolysis and the water may be 1:1 to 450, 1:1 to 400, 1:1 to 250, 1:1 to 100, 1:1 to 50, 1:1.2 to 20, or 1:1.5 to 10.

[0148] Additionally, a hydrolysis catalyst may be introduced in the above step (2). Specifically, hydrolysis may be performed by introducing a hydrolysis catalyst into a mixture of the alcoholysis reaction composition and water.

[0149] The above hydrolysis reaction can be performed smoothly without the use of a hydrolysis catalyst, making it environmentally friendly. In particular, when the content of insoluble metals in waste polyester is high, a non-catalytic reaction can be advantageous for the efficient treatment and removal of impurities. Furthermore, a hydrolysis catalyst can be added in step (2) from an energy perspective, enhancing reactivity and thus processability.

[0150] The hydrolysis catalyst may be a metal acetate salt, an alkali metal salt, or a hydroxy salt.

[0151] More specifically, the hydrolysis catalyst is Li + , Na + , K + or Cs + Alkali metal ions, Be 2+ , Mg 2+ , Ca 2+ or Ba 2+ Alkaline earth metal ions, NH 4+ or NR 4+ Ammonium ion of (R is alkyl), and Zn 2+ One or more cations selected from the group consisting of; and OH - , OR - (R is alkyl), HCO3 - , CO3 2- , benzoate ion (C7H5O2 - ), may include at least one anion selected from the group consisting of 4-alkoxycarbonylbenzoate ion, acetate ion, and terephthalate ion. The R may be an alkyl having 1 to 10 carbon atoms or an alkyl having 1 to 5 carbon atoms.

[0152] For example, the hydrolysis catalyst may be Zn(OAC)2, Co(OAc)2, Mn(OAc)2, Mg(OAc)2, Ca(OAc)2, Ba(OAc)2, LiOAc, NaOAc, KOAc, Zn(OAC)2·2H2O, Co(OAc)2·4H2O, Pb(OAc)2, Mn(OAc)2·4H2O, Mg(OAc)2·4H2O, Pd(OAc)2, It may include at least one selected from the group consisting of Ti(OBu)4, Ti(OiPr)4, GeO2, Al(OiPr)3, Na2CO3, K2CO3, dibutyltin(IV) oxide, tin octoate, titanium phosphate, and terephthalic acid.

[0153] The amount of the hydrolysis catalyst may be 10 ppm to 10,000 ppm relative to the total weight of the composition. For example, the amount of the hydrolysis catalyst may be 15 ppm to 8,000 ppm, 20 ppm to 5,500 ppm, 30 ppm to 3,000 ppm, 50 ppm to 1,600 ppm, 100 ppm to 1,200 ppm, 150 ppm to 1,100 ppm, 300 ppm to 1,000 ppm, 350 ppm to 950 ppm, 400 ppm to 850 ppm, 420 ppm to 700 ppm, or 450 ppm to 650 ppm relative to the total weight of the alcoholysis reaction composition (purified, or purified and concentrated alcoholysis reaction composition).

[0154] According to one embodiment of the present invention, solid-phase regenerated terephthalic acid can be produced through the hydrolysis reaction. Specifically, after the hydrolysis step, a step of filtering, washing, and drying the hydrolysis reaction product produced by the hydrolysis reaction may be additionally included. That is, solid-phase regenerated terephthalic acid can be produced by filtering, washing, and drying the hydrolysis reaction product produced by the hydrolysis reaction.

[0155] For example, the hydrolysis reaction product can be cooled to an appropriate temperature, such as room temperature to less than 100°C, at which water does not vaporize, to obtain a slurry-like solution, which can be filtered to obtain a solid, which can then be washed and vacuum-dried to obtain solid-state regenerated terephthalic acid.

[0156] The above washing can be performed using a mixture of alcohol having 4 or more carbon atoms and / or water, a protic solvent such as isopropanol or acetic acid, or an aprotic solvent such as acetone, dichloromethane, chloroform, tetrahydrofuran (THF), or toluene.

[0157] At this time, the description regarding the alcohol having a carbon number of 4 or more is as described above, and the alcohol having a carbon number of 4 or more used for the washing may be the same as or different from the alcohol having a carbon number of 4 or more used in the step (1). For example, when 1-butanol is used as the alcohol in the step (1) for producing terephthalic acid, the produced solid terephthalic acid may be washed with a mixture of 1-butanol and water. In addition, the carbon number of the alcohol used for the washing may be the same as the carbon number of the alcohol used in the step (1).

[0158] By effectively removing residual pigments or yellow impurities resulting from pigment decomposition during hydrolysis through the above washing process, yellowness and color characteristics can be improved. Furthermore, by using water for washing, inorganic salts can be removed, thereby improving quality.

[0159] Additionally, the yield of the above-mentioned recycled terephthalic acid may be 65% or more. For example, the yield of the above-mentioned finally manufactured recycled terephthalic acid may be 68% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more.

[0160]

[0161] A step of preparing a preliminary composition by mixing the above-mentioned recycled terephthalic acid with a glycol component.

[0162] A method for producing a polyester resin according to another embodiment of the present invention includes a step of producing a preliminary composition by mixing the recycled terephthalic acid with a glycol component.

[0163] Additionally, a diacid component may be additionally mixed in the step of preparing the preliminary composition. The diacid component and the glycol component are described as above.

[0164] Additionally, in the step of preparing the preliminary composition, one or more additives selected from the group including a coloring agent, a crystallizing agent, an oxidation stabilizer, and a branching agent may be additionally added. The description of the additives is as described above.

[0165]

[0166] A step of subjecting the above preliminary composition to an esterification reaction

[0167] A method for producing a polyester resin according to another embodiment of the present invention includes a step of subjecting the preliminary composition to an esterification reaction.

[0168] The above esterification reaction can be carried out at a temperature of 200°C to 350°C, 220°C to 320°C, or 250°C to 290°C. In addition, the above esterification reaction can be carried out at a temperature of 0 kg / cm compared to atmospheric pressure. 2 10 kg / cm 2 (0 mmHg to 7355.6 mmHg), 0 kg / cm 2 5 kg / cm 2 (0 to 3677.8 mmHg) or 0 kg / cm 2 2.0 kg / cm 2(0 to 1471.1 mmHg). In addition, the esterification reaction can be performed for 1 hour to 24 hours, 1 hour to 10 hours, or 1 hour to 6 hours.

[0169]

[0170] A step of subjecting the above esterification reaction product to a polycondensation reaction.

[0171] A method for producing a polyester resin according to another embodiment of the present invention includes a step of subjecting the esterification reaction product to a polycondensation reaction.

[0172] In addition, the polycondensation reaction can be carried out at a temperature of 150°C to 400°C, 200°C to 370°C, 250°C to 350°C, or 270°C to 300°C. In addition, the polycondensation reaction can be carried out under reduced pressure conditions of 0.01 mmHg to 400 mmHg, 0.05 mmHg to 100 mmHg, or 0.1 mmHg to 100 mmHg. In addition, the polycondensation reaction can be carried out for a necessary time until the desired intrinsic viscosity is reached, and for example, can be carried out for 1 hour to 24 hours, 1 hour to 10 hours, or 1 hour to 4 hours.

[0173] At the beginning of the polycondensation reaction, the stirring speed is set to high, and as the polycondensation reaction progresses, the stirring force becomes weak due to the increase in the viscosity of the reactants, or the temperature of the reactants rises above the set temperature, the stirring speed can be appropriately adjusted accordingly.

[0174] Additionally, a catalyst and / or stabilizer may be additionally added in the esterification reaction and the polycondensation reaction.

[0175] For example, the esterification reaction catalyst may be a methylate of sodium or magnesium; an acetate, borate, fatty acid salt, or carbonate of Zn, Cd, Mn, Co, Ca, or Ba; a metal Mg; an oxide of Pb, Zn, Sb, Ge, or Ti; or the like.

[0176] In addition, the polycondensation reaction catalyst may be, for example, a titanium-based catalyst such as tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, lactate titanate, triethanolamine titanate, acetyl acetonate titanate, ethyl acetoacetic ester titanate, isostearyl titanate, titanium dioxide, titanium dioxide / silicon dioxide copolymer, titanium dioxide / zirconium dioxide copolymer, etc.; a germanium-based catalyst such as germanium dioxide and copolymers using the same; or a tin-based catalyst such as monobutyl tin oxide, dibutyl tin oxide, monobutyl hydroxy tin oxide, etc.

[0177] Additionally, the stabilizer may be a phosphorus compound such as phosphoric acid, trimethyl phosphate, or triethyl phosphate, but is not limited thereto.

[0178] A method for producing a polyester resin according to another embodiment of the present invention may further include a step of conducting a solid-state polymerization reaction. For example, the solid-state polymerization may be performed after the polycondensation reaction step, and may be performed at a temperature of 190°C to 230°C, under vacuum conditions of 0.2 torr to 2.0 torr, or under a nitrogen atmosphere.

[0179] The above contents are explained in more detail with the following examples. However, the following examples are only intended to illustrate the present invention, and the scope of the examples is not limited to these examples.

[0180]

[0181] [Example]

[0182] Preparation of liquid composition

[0183] Example 1-1

[0184] 1 kg of waste polyethylene terephthalate (waste PET) and 3.3 kg of 1-butanol as alcohol were charged into a first high-pressure reactor with a capacity of 7 L, and 200 mg of Zn(OAC)2·2H2O (200 ppm based on the total weight of the waste PET) as an alcoholysis catalyst was added.

[0185] Afterwards, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 250°C over 1 hour. Then, the alcoholysis reaction was carried out by stirring for 3 hours while maintaining the temperature at 250°C and the pressure at 24 bar.

[0186] After the alcoholysis reaction was completed, the mixture was cooled to room temperature to obtain a liquid alcoholysis reaction composition. At this time, the components and contents of the alcoholysis reaction composition were analyzed using NMR. The alcoholysis reaction composition contained a compound represented by the following chemical formula 1 (R1: (CH2)3CH3), residual ethylene glycol (EG), alcohol (1-butanol), and oligomers.

[0187] Thereafter, the alcoholysis reaction composition was placed in a separate flask, and the excess unreacted 1-butanol and the produced ethylene glycol (EG) were each recovered using a fractional distillation device.

[0188] [Chemical Formula 1]

[0189]

[0190]

[0191] Example 1-2

[0192] 1 kg of waste polyethylene terephthalate (waste PET) and 3.3 kg of 1-butanol as alcohol were charged into a first high-pressure reactor with a capacity of 7 L, and 200 mg of Zn(OAC)2·2H2O (200 ppm based on the total weight of the waste PET) as an alcoholysis catalyst was added.

[0193] Afterwards, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 250°C over 1 hour. Then, the alcoholysis reaction was carried out by stirring for 3 hours while maintaining the temperature at 250°C and the pressure at 24 bar.

[0194] Specifically, after 1 hour from the start of the alcoholysis reaction, the valve of the pre-installed back pressure regulator was adjusted to discharge the gaseous mixture of ethylene glycol (EG), a by-product produced by the alcoholysis reaction, and 1-butanol present in excess. At this time, the internal temperature of the first high-pressure reactor was continuously maintained at 250°C, and the gaseous mixture of ethylene glycol (EG) and 1-butanol discharged through the back pressure regulator was condensed using an external cooling device. In addition, the discharge rate of the gaseous mixture of ethylene glycol (EG) and 1-butanol discharged was adjusted to 3 kg / h, and at the same time, 1-butanol was continuously supplied to the first high-pressure reactor. At this time, the capacity and input rate of 1-butanol newly supplied to the first high-pressure reactor were adjusted to be the same as the capacity and discharge rate of the gaseous mixture of ethylene glycol (EG) and 1-butanol discharged. The alcoholysis reaction was carried out while maintaining the above discharge and supply processes for 3 hours.

[0195] After the alcoholysis reaction was completed, the mixture was cooled to room temperature to obtain a liquid alcoholysis reaction composition. At this time, the components and contents of the alcoholysis reaction composition were analyzed using NMR. The alcoholysis reaction composition contained a compound represented by the following chemical formula 1 (R1: (CH2)3CH3), residual ethylene glycol (EG), alcohol (1-butanol), and oligomers.

[0196] Afterwards, the alcoholysis reaction composition was placed in a separate flask, and the excess unreacted 1-butanol and the produced ethylene glycol were each recovered using a fractional distillation device.

[0197] [Chemical Formula 1]

[0198]

[0199]

[0200] Example 1-3

[0201] 1 kg of waste polyethylene terephthalate (waste PET) and 3.3 kg of 1-butanol as alcohol were charged into a first high-pressure reactor with a capacity of 7 L, and 200 mg of Zn(OAC)2·2H2O (200 ppm based on the total weight of the waste PET) as an alcoholysis catalyst was added.

[0202] Afterwards, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 250°C over 1 hour. Then, the alcoholysis reaction was carried out by stirring for 3 hours while maintaining the temperature at 250°C and the pressure at 24 bar.

[0203] Specifically, after 1 hour from the start of the alcoholysis reaction, the valve of the pre-installed back pressure regulator was adjusted to discharge the gaseous mixture of ethylene glycol (EG), a by-product produced by the alcoholysis reaction, and 1-butanol present in excess. At this time, the internal temperature of the first high-pressure reactor was continuously maintained at 250°C, and the gaseous mixture of ethylene glycol (EG) and 1-butanol discharged through the back pressure regulator was condensed using an external cooling device. In addition, the discharge rate of the gaseous mixture of ethylene glycol (EG) and 1-butanol discharged was adjusted to 3 kg / h, and at the same time, 1-butanol was continuously supplied to the first high-pressure reactor. At this time, the capacity and input rate of 1-butanol newly supplied to the first high-pressure reactor were adjusted to be the same as the capacity and discharge rate of the gaseous mixture of ethylene glycol (EG) and 1-butanol discharged.

[0204] The above-described gaseous mixture of ethylene glycol (EG) and 1-butanol was transferred to a 5 L capacity layer separation device filled with 3 kg of water, and then the process of stirring for 10 minutes and layer separation for 2 minutes was repeated to separate the 1-butanol layer and the water / ethylene glycol (EG) layer. The separated 1-butanol was re-injected into the first high-pressure reactor in real time using a high-pressure pump and reused. The alcoholysis reaction was carried out while maintaining the stirring, layer separation, and re-injection processes for 3 hours.

[0205] After the alcoholysis reaction was completed, the mixture was cooled to room temperature to obtain a liquid alcoholysis reaction composition. At this time, the components and contents of the alcoholysis reaction composition were analyzed using NMR. The alcoholysis reaction composition contained a compound represented by the following chemical formula 1 (R1: (CH2)3CH3), residual ethylene glycol (EG), alcohol (1-butanol), and oligomers.

[0206] Afterwards, the alcoholysis reaction composition was placed in a separate flask, and the excess unreacted 1-butanol and the produced ethylene glycol were each recovered using a fractional distillation device.

[0207] [Chemical Formula 1]

[0208]

[0209]

[0210] Example 1-4

[0211] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-pentanol was used as the alcohol and the pressure was maintained at 13 bar.

[0212]

[0213] Example 1-5

[0214] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-2, except that 3.3 kg of 1-pentanol was used as the alcohol and the pressure was maintained at 13 bar.

[0215]

[0216] Example 1-6

[0217] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-3, except that 3.3 kg of 1-pentanol was used as the alcohol and the pressure was maintained at 13 bar.

[0218]

[0219] Example 1-7

[0220] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-octanol was used as the alcohol and the pressure was maintained at 3.4 bar.

[0221]

[0222] Example 1-8

[0223] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-2, except that 3.3 kg of 1-octanol was used as the alcohol and the pressure was maintained at 3.4 bar.

[0224]

[0225] Example 1-9

[0226] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-3, except that 3.3 kg of 1-octanol was used as the alcohol and the pressure was maintained at 3.4 bar.

[0227]

[0228] Example 1-10

[0229] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of 2-ethyl-1-hexanol was used as the alcohol and the pressure was maintained at 4.1 bar.

[0230]

[0231] Example 1-11

[0232] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-2, except that 3.3 kg of 2-ethyl-1-hexanol was used as the alcohol and the pressure was maintained at 4.1 bar.

[0233]

[0234] Example 1-12

[0235] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-3, except that 3.3 kg of 2-ethyl-1-hexanol was used as the alcohol and the pressure was maintained at 4.1 bar.

[0236]

[0237] Example 1-13

[0238] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-decanol was used as the alcohol and the pressure was maintained at 1.6 bar.

[0239]

[0240] Example 1-14

[0241] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-2, except that 3.3 kg of 1-decanol was used as the alcohol and the pressure was maintained at 1.6 bar.

[0242]

[0243] Example 1-15

[0244] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-3, except that 3.3 kg of 1-decanol was used as the alcohol and the pressure was maintained at 1.6 bar.

[0245]

[0246] Example 1-16

[0247] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-dodecanol was used as the alcohol and the pressure was maintained at 1.0 bar.

[0248]

[0249] Example 1-17

[0250] 1 kg of waste polyethylene terephthalate (waste PET) and 3.3 kg of 1-dodecanol as alcohol were charged into a first high-pressure reactor with a capacity of 7 L, and 200 mg of Zn(OAC)2·2H2O (200 ppm based on the total weight of the waste PET) as an alcohol decomposition catalyst was added.

[0251] Afterwards, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 250°C over 1 hour. Then, the alcoholysis reaction was performed by stirring for 3 hours while maintaining the temperature at 250°C and the pressure at 1.0 bar.

[0252] Specifically, after one hour from the start of the alcoholysis reaction, the valve of the pre-installed back pressure regulator was adjusted to discharge the vapor of ethylene glycol (EG), a by-product produced by the alcoholysis reaction. At this time, the internal temperature of the first high-pressure reactor was continuously maintained at 250°C, and the discharged vapor of ethylene glycol (EG) was condensed using an external cooling device.

[0253] In addition, 1-dodecanol was continuously supplied to the first high-pressure reactor in an amount equal to the amount of ethylene glycol (EG) discharged as steam and condensed. At this time, the capacity and feeding rate of 1-dodecanol newly supplied to the first high-pressure reactor were adjusted to be the same as the capacity and discharge rate of the discharged ethylene glycol (EG). The alcoholysis reaction was carried out while maintaining the discharge and supply processes for 3 hours.

[0254] After the alcoholysis reaction was completed, the mixture was cooled to room temperature to obtain a liquid alcoholysis reaction composition. At this time, the components and their contents of the alcoholysis reaction composition were analyzed through NMR. The alcoholysis reaction composition is a compound represented by the following chemical formula 1 (R1: (CH2) 11 CH3), residual ethylene glycol (EG), alcohol (1-dodecanol) and oligomers.

[0255] Thereafter, the alcoholysis reaction composition was placed in a separate flask, and the excess unreacted 1-dodecanol and the produced ethylene glycol (EG) were each recovered using a fractional distillation device.

[0256] [Chemical Formula 1]

[0257]

[0258]

[0259] Example 1-18

[0260] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-tetradecanol was used as the alcohol and the pressure was maintained at 1.0 bar.

[0261]

[0262] Example 1-19

[0263] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-17, except that 3.3 kg of 1-tetradecanol was used as the alcohol.

[0264]

[0265] Comparative Example 1-1

[0266] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of methanol was used as the alcohol and the pressure was maintained at 83 bar.

[0267]

[0268] Comparative Example 1-2

[0269] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-2, except that 3.3 kg of methanol was used as the alcohol and the pressure was maintained at 83 bar.

[0270]

[0271] Comparative Example 1-3

[0272] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-1, except that 3.3 kg of ethanol was used as the alcohol and the pressure was maintained at 64 bar.

[0273]

[0274] Comparative Example 1-4

[0275] A liquid alcoholysis reaction composition was prepared in the same manner as in Example 1-2, except that 3.3 kg of ethanol was used as the alcohol and the pressure was maintained at 64 bar.

[0276]

[0277]

[0278]

[0279] As shown in Table 1 above, the liquid alcoholysis reaction compositions of Examples 1-1 to 1-19 were manufactured using alcohols having 4 or more carbon atoms, and thus could be manufactured at a much lower process pressure than Comparative Examples 1-1 to 1-4, while having a high content of the compound represented by Chemical Formula 1, i.e., a high yield and purity, and an excellent recovery rate of ethylene glycol.

[0280]

[0281] Purification and concentration of liquid compositions

[0282] Example 2-1

[0283] In the above Example 1-1, 100 g of the liquid alcoholysis reaction composition before recovering the excess unreacted alcohol and the produced ethylene glycol using a fractional distillation device was purified by adding 0.1 g of activated carbon as an adsorbent, stirred at 100°C for 3 hours, and then filtered to concentrate the alcoholysis reaction composition.

[0284]

[0285] Examples 2-2 to 2-23, Comparative Examples 2-1 and 2-2

[0286] Except for the different liquid composition and process conditions as shown in Table 2 below, the liquid alcoholysis reaction composition was purified and concentrated in the same manner as in Example 2-1. However, Comparative Examples 2-1 and 2-2 were precipitated in an undissolved state and were not purified.

[0287]

[0288] Examples 2-24 to 2-26

[0289] In each of the above Examples 1-1, 1-4 and 1-10, 0.1 g of activated carbon was added as an adsorbent to 100 g of the liquid alcoholysis reaction composition after recovering the excess unreacted alcohol and the generated ethylene glycol using a fractional distillation device, and the composition was purified by stirring at 100°C for 3 hours and then filtering to concentrate the alcoholysis reaction composition.

[0290]

[0291] Comparative Examples 2-3 to 2-21

[0292] In Examples 1-1 to 1-19, the liquid alcoholysis reaction composition before recovering the excess unreacted alcohol and the generated ethylene glycol using a fractional distillation device was stirred at 100°C for 3 hours without adding an adsorbent, and then filtered and concentrated.

[0293]

[0294] Experimental Example 1-1: Pigment Residue

[0295] The pigment residue rate (%) was calculated for the compositions of Examples 2-1 to 2-26 and Comparative Examples 2-1 to 2-21.

[0296] Specifically, the composition of Example 2-1 was diluted to a concentration of 5% using dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and methylpyrrolidone (NMP), and then the absorbance curve at 400 nm to 800 nm was obtained using a UV-vis spectrophotometer, and its area (A1) was measured. In addition, for the composition of Comparative Example 2-3 (a composition that was concentrated without adding an adsorbent and purifying the composition using the composition of Example 1-1 in the same manner as the composition of Example 2-1), the absorbance curve at 400 nm to 800 nm was obtained using the same method as above, and its area (A2) was measured. The pigment residue rate (%) was calculated according to the following formula A using the area of ​​the measured absorbance curve.

[0297] [Formula A]

[0298]

[0299] In the same manner as above, the pigment residue rate (%) was calculated for the compositions of Examples 2-2 to 2-26 and Comparative Examples 2-1 to 2-21.

[0300]

[0301] Experimental Example 1-2: Yellowness

[0302] For the compositions of Examples 2-1 to 2-26 and Comparative Examples 2-1 to 2-21, the yellowness index (YI) was measured.

[0303] Specifically, the compositions of Examples 2-1 to 2-26 and Comparative Examples 2-1 to 2-21 were diluted to a concentration of 5% by adding them to a solvent, and then the yellowness was measured using a ColorFlex EZ (manufacturer: HunterLab) device. At this time, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or methylpyrrolidone (NMP) was used as the solvent.

[0304]

[0305] Experimental Example 1-3: Metal content

[0306] The content (ppm) of metals present in the compositions of Examples 2-1 to 2-26 and Comparative Examples 2-1 to 2-21 was measured using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). ND means that the content is less than 1 ppm, which is too low to be measured as a specific numerical value.

[0307]

[0308]

[0309]

[0310]

[0311]

[0312] As shown in Table 2 above, the purified and concentrated alcoholysis reaction compositions of Examples 2-1 to 2-26 had very low pigment residues and also very low contents of metals such as Sb, Ti, and Zn.

[0313]

[0314] Production of recycled terephthalic acid

[0315] Example 3-1

[0316] 100 g (0.36 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-2 and 200 g (11.10 mol) of water were charged into a second high-pressure reactor with a capacity of 600 ml, and 50 mg of Zn(OAC)2·2H2O (500 ppm based on the total weight of the purified and concentrated alcoholysis reaction composition) was added as a hydrolysis catalyst.

[0317] Thereafter, the temperature of the second high-pressure reactor was raised to 260°C, and the hydrolysis reaction was carried out for 4 hours while maintaining the temperature at 260°C, and then cooled to 90°C to obtain a slurry-type hydrolysis reaction product. The slurry-type hydrolysis reaction product was filtered, and the obtained solid was washed with butanol and water at 90°C and vacuum-dried to obtain 53.7 g (yield: 90%) of solid-phase regenerated terephthalic acid (TPA).

[0318]

[0319] Example 3-2

[0320] 100 g (0.30 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-5 and 200 g (11.10 mol) of water were charged into a second high-pressure reactor with a capacity of 600 ml, and 50 mg of Zn(OAC)2·2H2O (500 ppm based on the total weight of the purified and concentrated alcoholysis reaction composition) was added as a hydrolysis catalyst.

[0321] Thereafter, the temperature of the second high-pressure reactor was raised to 260°C, and the hydrolysis reaction was carried out for 4 hours while maintaining the temperature at 260°C, and then cooled to 90°C to obtain a hydrolysis reaction product in the form of a slurry. The slurry-form hydrolysis reaction product was filtered, and the obtained solid was washed with pentanol and water at 90°C and vacuum-dried to obtain 43.9 g (yield: 81%) of solid-phase regenerated terephthalic acid (TPA).

[0322]

[0323] Example 3-3

[0324] 100 g (0.26 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-11 and 1,000 g (55.50 mol) of water were charged into a second high-pressure reactor with a capacity of 600 ml, and 50 mg of Zn(OAC)2·2H2O (500 ppm based on the total weight of the purified and concentrated alcoholysis reaction composition) was added as a hydrolysis catalyst.

[0325] Thereafter, the temperature of the second high-pressure reactor was raised to 260°C, and the hydrolysis reaction was carried out for 4 hours while maintaining 260°C, and then cooled to 90°C to obtain a slurry-type hydrolysis reaction product. The slurry-type hydrolysis reaction product was filtered, and the obtained solid was washed with 2-ethyl-1-hexanol and water at 90°C, and vacuum-dried to obtain 38.0 g (yield: 88%) of solid-phase regenerated terephthalic acid (TPA).

[0326]

[0327] Example 3-4

[0328] Except that 100 g (0.26 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-13 was used, 35.4 g (yield: 82%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-3.

[0329]

[0330] Example 3-5

[0331] Except that 100 g (0.26 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-14 was used, 36.7 g (yield: 85%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-3.

[0332]

[0333] Example 3-6

[0334] 114 g (0.26 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-18 and 200 g (11.10 mol) of water were charged into a second high-pressure reactor with a capacity of 600 ml, and 57 mg of Zn(OAC)2·2H2O (500 ppm based on the total weight of the purified and concentrated alcoholysis reaction composition) was added as a hydrolysis catalyst.

[0335] Thereafter, the temperature of the second high-pressure reactor was raised to 260°C, and the hydrolysis reaction was carried out for 4 hours while maintaining 260°C, and then cooled to 90°C to obtain a slurry-type hydrolysis reaction product. The slurry-type hydrolysis reaction product was filtered, and the obtained solid was washed with 90°C decanol and water, and vacuum-dried to obtain 36.1 g (yield: 85%) of solid-phase regenerated terephthalic acid (TPA).

[0336]

[0337] Example 3-7

[0338] Except that the hydrolysis catalyst was not added, 54.3 g (yield: 91%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-1.

[0339]

[0340] Example 3-8

[0341] 100 g (0.36 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-2 and 200 g (11.10 mol) of water were charged into a second high-pressure reactor with a capacity of 600 ml, and 50 mg of Zn(OAC)2·2H2O (500 ppm based on the total weight of the purified and concentrated alcoholysis reaction composition) was added as a hydrolysis catalyst.

[0342] Thereafter, the temperature of the second high-pressure reactor was raised to 260°C, and a hydrolysis reaction was performed for 4 hours while maintaining 260°C, and then cooled to 90°C to obtain a slurry-type hydrolysis reaction product. The slurry-type hydrolysis reaction product was filtered, and acetone was added to the obtained solid, and stirred at 50°C for 4 hours. After filtering, the solid was washed with acetone and water at 50°C, and vacuum-dried to obtain 55.6 g (yield: 93%) of solid-phase regenerated terephthalic acid (TPA).

[0343]

[0344] Example 3-9

[0345] 100 g (0.36 mol) of the purified and concentrated alcoholysis reaction composition of Example 2-2 and 200 g (11.10 mol) of water were charged into a second high-pressure reactor with a capacity of 600 ml, and 50 mg of Zn(OAC)2·2H2O (500 ppm based on the total weight of the purified and concentrated alcoholysis reaction composition) was added as a hydrolysis catalyst.

[0346] Thereafter, the temperature of the second high-pressure reactor was raised to 260°C, and a hydrolysis reaction was performed for 4 hours while maintaining 260°C, and then cooled to 90°C to obtain a slurry-type hydrolysis reaction product. The slurry-type hydrolysis reaction product was filtered, and butanol was added to the obtained solid, and stirred at 90°C for 4 hours. After filtering, it was washed with butanol and water at 50°C, and vacuum-dried to obtain 53.1 g (yield: 89%) of solid-phase regenerated terephthalic acid (TPA).

[0347]

[0348] Example 3-10

[0349] Except that the filtrate separated through the filtration process in Example 3-1 was additionally used, 59.2 g (yield: 99%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-1.

[0350] Specifically, the filtrate separated through the filtration process of Example 3-1 was placed back into the second high-pressure reactor, the temperature was raised to 260°C, and a hydrolysis reaction was performed for 4 hours while maintaining the temperature at 260°C, and then cooled to 90°C to obtain a slurry-type hydrolysis reaction product. The slurry-type hydrolysis reaction product was filtered, and the obtained solid was washed with butanol and water at 90°C and vacuum-dried to additionally obtain 5.5 g of solid-phase regenerated terephthalic acid (TPA).

[0351]

[0352] Comparative Example 3-1

[0353] Except that 100 g (0.36 mol) of the composition of Comparative Example 2-4 was used, 54.4 g (yield: 91%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-1.

[0354]

[0355] Comparative Example 3-2

[0356] Except that 100 g (0.30 mol) of the composition of Comparative Example 2-7 was used, 40.4 g (yield: 81%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-2.

[0357]

[0358] Comparative Example 3-3

[0359] Except that 100 g (0.26 mol) of the composition of Comparative Example 2-13 was used, 36.7 g (yield: 85%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-3.

[0360]

[0361] Comparative Example 3-4

[0362] Except that 114 g (0.26 mol) of the composition of Comparative Example 2-16 was used, 34.4 g (yield: 81%) of solid-phase regenerated terephthalic acid (TPA) was obtained in the same manner as in Example 3-6.

[0363]

[0364] Experimental Example 2-1: Pigment Residue

[0365] The pigment residue rate (%) was calculated for the terephthalic acid of Examples 3-1 to 3-10 and Comparative Examples 3-1 to 3-4.

[0366] Specifically, the terephthalic acid of Example 3-1 was diluted to a concentration of 5% in a solvent, and then an absorbance curve at 400 nm to 800 nm was obtained using a UV-vis spectrophotometer, and its area (B1) was measured. At this time, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), or methyl pyrrolidone (NMP) was used as the solvent. In addition, for the composition of Comparative Example 2-4 (the composition of Example 1-2 used in the production of the terephthalic acid of Example 3-1 was used in the same manner, but the concentrated composition was obtained without adding an adsorbent), and an absorbance curve at 400 nm to 800 nm was measured using the same method as above, and its area (B2) was measured. The pigment residue rate (%) was calculated according to the following formula B using the area of ​​the measured absorbance curve.

[0367] [Formula B]

[0368]

[0369] The pigment residue rate (%) of terephthalic acid was calculated for Examples 3-2 to 3-10 and Comparative Examples 3-1 to 3-4 in the same manner as above. Specifically, with respect to B2 of the above formula 1, Example 3-2 was measured using the composition of Comparative Example 2-7, Examples 3-3 to 3-5 were measured using the composition of Comparative Example 2-13, and Example 3-6 was measured using the composition of Comparative Example 2-16. In addition, Comparative Examples 3-1 to 3-4 were measured using the compositions of Comparative Examples 2-4, 2-7, 2-13, and 2-16, respectively, to measure B2 of the above formula 1.

[0370]

[0371] Experimental Example 2-2: Yellowness

[0372] For the regenerated terephthalic acid of Examples 3-1 to 3-10 and Comparative Examples 3-1 to 3-4, the yellowness index (YI) was measured.

[0373] Specifically, the recycled terephthalic acid of Examples 3-1 to 3-10 and Comparative Examples 3-1 to 3-4 was diluted to a concentration of 5% by adding a solvent, and then the yellowness was measured using a ColorFlex EZ (manufacturer: HunterLab) device. At this time, the solvent used was dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or methylpyrrolidone (NMP).

[0374]

[0375] Experimental Example 2-2: Metal content

[0376] The content (ppm) of metals present in the terephthalic acid of Examples 3-1 to 3-10 and Comparative Examples 3-1 to 3-4 was measured using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). ND means that the content is less than 1 ppm, which is too low to be measured as a specific numerical value.

[0377]

[0378] Experimental Example 2-3: Color b

[0379] For the terephthalic acid of Examples 3-1 to 3-10 and Comparative Examples 3-1 to 3-4, the color characteristic Color b was measured using a spectrophotometer.

[0380] Specifically, for the above-mentioned recycled terephthalic acid, a Varian Cary 5 UV / Vis / NIR spectrophotometer equipped with a diffuse reflectance accessory capable of measuring color and brightness was used, and data was obtained through reflectance mode with Illuminant D65 at an observer angle of 2°, and the Color b value was calculated by processing it with a color analysis device within the Grams / 32 software.

[0381]

[0382]

[0383]

[0384] As shown in Table 3 above, the regenerated terephthalic acid produced in Examples 3-1 to 3-6 not only had a Color b that satisfied a specific range, but also had a low pigment residue and yellowness, and also had a very low content of metal impurities. In particular, Example 3-10 was able to obtain regenerated terephthalic acid in a very high yield by utilizing the filtrate separated through the filtration process, i.e., unreacted material.

[0385]

[0386] Manufacturing of polyester resin

[0387] Example 4-1

[0388] (a) Preparation of preliminary composition

[0389] Into a 10 L reactor connected to a column and a condenser capable of being cooled by water, 5810.6 g of reproduced terephthalic acid (r-TPA), 3810.4 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 1333.1 g of ethylene glycol (EG), 864.1 g of cyclohexanedimethanol (CHDM), 292.0 g of isosorbide (ISB), and 73.0 g of diethylene glycol (DEG) prepared in Example 3-1 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.2.

[0390] Afterwards, 12.8 g of Ge catalyst, 10.0 g of phosphoric acid as a stabilizer, 0.010 g of blue toner, 0.005 g of red toner, and 1000 ppm of hindered phenolic oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0391] (b) Esterification reaction

[0392] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 1.0 kgf / cm compared to the atmospheric pressure. 2 The reactor was pressurized to a high pressure (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0393] (c) polycondensation reaction

[0394] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 270°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.70 dl / g, and then the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to have an average weight of about 12 mg to 14 mg.

[0395] (d) solid-state polymerization reaction

[0396] Next, the particles of the above step (c) were left at 150°C for 1 hour to crystallize, and then placed in a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the reactor at a rate of 50 L / min. At this time, the temperature of the reactor was increased from room temperature to 140°C at a rate of 40°C / hour, maintained at 140°C for 3 hours, and then increased to 200°C at a rate of 40°C / hour and maintained at 200°C. The solid-state polymerization reaction was carried out until the intrinsic viscosity (IV) of the particles in the reactor became 1.30 dl / g, thereby producing a polyester resin.

[0397]

[0398] Example 4-2

[0399] (a) Preparation of preliminary composition

[0400] In a 10 L reactor connected to a column and a condenser capable of being cooled by water, 8419.6 g of the reproduced terephthalic acid (r-TPA) produced in Example 3-2, 6341.7 g of ethylene glycol (EG), 365.2 g of cyclohexanedimethanol (CHDM), 98.7 g of isosorbide (ISB), and 148.1 g of diethylene glycol (DEG) were charged. At this time, G / A (total diol / total diacid, G / A (total diol / total diacid, molar ratio of the glycol component to the diacid component) was 2.1.

[0401] Afterwards, 6.4 g of Ge catalyst, 0.030 g of blue toner, and 0.015 g of red toner were added and stirred to prepare a preliminary composition.

[0402] (b) Esterification reaction

[0403] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 2.0 kgf / cm compared to the atmospheric pressure. 2 The reactor was pressurized to a high pressure (absolute pressure: 2231.2 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0404] (c) polycondensation reaction

[0405] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 280°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.60 dl / g, and then the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to have an average weight of about 12 mg to 14 mg.

[0406] (d) solid-state polymerization reaction

[0407] Next, the particles of the above step (c) were left at 150°C for 1 hour to crystallize, and then placed in a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the reactor at a rate of 50 L / min. At this time, the temperature of the reactor was increased from room temperature to 140°C at a rate of 40°C / hour, maintained at 140°C for 3 hours, and then increased to 210°C at a rate of 40°C / hour and maintained at 210°C. The solid-state polymerization reaction was carried out until the intrinsic viscosity (IV) of the particles in the reactor became 0.85 dl / g, thereby producing a polyester resin.

[0408]

[0409] Example 4-3

[0410] (a) Preparation of preliminary composition

[0411] In a 10 L reactor connected to a column and a condenser capable of being cooled by water, 4195.3 g of reproduced terephthalic acid (r-TPA), 4195.3 g of terephthalic acid (TPA), 4794.8 g of ethylene glycol (EG), 145.6 g of cyclohexanedimethanol (CHDM), and 369.0 g of diethylene glycol (DEG) prepared in Example 3-3 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.6, and the molar ratio of r-TPA to TPA was 1:1.

[0412] Afterwards, 6.4 g of Ge catalyst, 0.9 g of Ti catalyst, 1.0 g of phosphoric acid as a stabilizer, 0.040 g of blue toner, 0.010 g of red toner, and 100 ppm of hindered phenol-based oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0413] (b) Esterification reaction

[0414] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 0.5 kgf / cm compared to the atmospheric pressure. 2The reactor was pressurized to a high pressure (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0415] (c) polycondensation reaction

[0416] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 275°C over 1 hour, and the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.70 dl / g, and then the mixture was discharged outside the reactor to form strands, which were solidified with a cooling liquid and then granulated to an average weight of about 12 mg to 14 mg to produce a polyester resin.

[0417]

[0418] Example 4-4

[0419] (a) Preparation of preliminary composition

[0420] Into a 10 L reactor connected to a column and a condenser capable of being cooled by water, 2486.5 g of reproduced terephthalic acid (r-TPA), 4973.0 g of terephthalic acid (TPA), 1268.2 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 2600.4 g of ethylene glycol (EG), 431.4 g of cyclohexanedimethanol (CHDM), and 364.5 g of diethylene glycol (DEG) prepared in Example 3-4 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.15, and the molar ratio of r-TPA and TPA was 1:2.

[0421] Afterwards, 0.4 g of Ti catalyst, 2.0 g of phosphoric acid as a stabilizer, 2.1 g of cobalt acetate as a coloring agent, and 200 ppm of a hindered phenol-based oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0422] (b) Esterification reaction

[0423] Next, nitrogen is injected into the reactor containing the preliminary composition of the above step (a) so that the pressure of the reactor is 1.0 kgf / cm compared to the atmospheric pressure. 2The reactor was pressurized to a high pressure (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 250°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 250°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0424] (c) polycondensation reaction

[0425] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 265°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.60 dl / g, and then the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to have an average weight of about 12 mg to 14 mg.

[0426] (d) solid-state polymerization reaction

[0427] Next, the particles of the above step (c) were left at 150°C for 1 hour to crystallize, and then placed in a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the reactor at a rate of 50 L / min. At this time, the temperature of the reactor was increased from room temperature to 140°C at a rate of 40°C / hour, maintained at 140°C for 3 hours, and then increased to 220°C at a rate of 40°C / hour and maintained at 220°C. The solid-state polymerization reaction was carried out until the intrinsic viscosity (IV) of the particles in the reactor became 1.00 dl / g, thereby producing a polyester resin.

[0428]

[0429] Example 4-5

[0430] (a) Preparation of preliminary composition

[0431] In a 10 L reactor connected to a column and a condenser that can be cooled by water, 754.8 g of reproduced terephthalic acid (r-TPA), 1887.0 g of terephthalic acid (TPA), 7507.3 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 1268.6 g of ethylene glycol (EG), 2095.3 g of cyclohexanedimethanol (CHDM), and 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate prepared in Example 3-5 were charged. 199.2 g of a compound containing 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol in a molar ratio of 1:3 was added. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 2.1, and the molar ratio of r-TPA and TPA was 1:2.5.

[0432] Afterwards, 12.8 g of Ge catalyst, 0.9 g of Ti catalyst, 1.0 g of phosphoric acid as a stabilizer, 1.3 g of cobalt acetate as a coloring agent, 0.006 g of blue toner, 0.002 g of red toner, and 100 ppm of hindered phenolic oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0433] (b) Esterification reaction

[0434] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 2.0 kgf / cm compared to the atmospheric pressure. 2 The reactor was pressurized to a high pressure (absolute pressure: 2231.2 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 255°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 255°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to normal pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0435] (c) polycondensation reaction

[0436] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 285°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.78 dl / g, and then the mixture was discharged outside the reactor to form strands, which were solidified with a cooling liquid and then granulated to an average weight of about 12 mg to 14 mg to produce a polyester resin.

[0437]

[0438] Example 4-6

[0439] (a) Preparation of preliminary composition

[0440] Into a 10 L reactor connected to a column and a condenser capable of being cooled by water, 6640.6 g of reproduced terephthalic acid (r-TPA), 368.9 g of terephthalic acid (TPA), 564.5 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 3279.4 g of ethylene glycol (EG), 1984.2 g of cyclohexanedimethanol (CHDM), and 648.9 g of diethylene glycol (DEG) prepared in Example 3-6 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.7, and the molar ratio of r-TPA and TPA was 1:0.05.

[0441] Afterwards, 0.2 g of Ti catalyst, 2.0 g of phosphoric acid as a stabilizer, 2.7 g of cobalt acetate as a coloring agent, and 200 ppm of a hindered phenolic oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0442] (b) Esterification reaction

[0443] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 1.5 kgf / cm compared to the atmospheric pressure. 2The reactor was pressurized to a high pressure (absolute pressure: 1863.4 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 250°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 250°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0444] (c) polycondensation reaction

[0445] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 270°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.82 dl / g, and then the mixture was discharged outside the reactor to form strands, which were solidified with a cooling liquid and then granulated to an average weight of about 12 mg to 14 mg to produce a polyester resin.

[0446]

[0447] Example 4-7

[0448] (a) Preparation of preliminary composition

[0449] Into a 10 L reactor connected to a column and a condenser capable of being cooled by water, 5958.1 g of reproduced terephthalic acid (r-TPA), 1051.4 g of terephthalic acid (TPA), 898.9 g of ethylene glycol (EG), 4256.4 g of cyclohexanedimethanol (CHDM), 1890.6 g of isosorbide (ISB), and 616.5 g of diethylene glycol (DEG) prepared in Example 3-7 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.45, and the molar ratio of r-TPA and TPA was 1:0.18.

[0450] Afterwards, 64.0 g of Ge catalyst, 0.2 g of phosphoric acid as a stabilizer, 0.030 g of blue toner, 0.010 g of red toner, and 20 ppm of hindered phenolic oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0451] (b) Esterification reaction

[0452] Next, nitrogen is injected into the reactor containing the preliminary composition of the above step (a) so that the pressure of the reactor is 1.0 kgf / cm compared to the atmospheric pressure. 2The reactor was pressurized to a high pressure (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 265°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 265°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to normal pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0453] (c) polycondensation reaction

[0454] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 275°C over 1 hour, and the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.70 dl / g, and then the mixture was discharged outside the reactor to form strands, which were solidified with a cooling liquid and then granulated to an average weight of about 12 mg to 14 mg to produce a polyester resin.

[0455]

[0456] Example 4-8

[0457] (a) Preparation of preliminary composition

[0458] In a 10 L reactor connected to a column and a condenser that can be cooled by water, 1545.8 g of reproduced terephthalic acid (r-TPA), 3864.4 g of terephthalic acid (TPA), 3547.8 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 721.7 g of ethylene glycol (EG), 536.4 g of cyclohexanedimethanol (CHDM), 747.7 g of diethylene glycol (DEG), and 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate prepared in Example 3-8 were added. 407.9 g of a compound containing 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol in a molar ratio of 1:3 was added. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.1, and the molar ratio of r-TPA and TPA was 1:2.51.

[0459] Afterwards, 6.4 g of Ge catalyst, 1.0 g of phosphoric acid as a stabilizer, 0.050 g of blue toner, 0.020 g of red toner, and 100 ppm of hindered phenolic oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0460] (b) Esterification reaction

[0461] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 0.5 kgf / cm compared to the atmospheric pressure. 2The reactor was pressurized to a high pressure (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0462] (c) polycondensation reaction

[0463] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 275°C over 1 hour, and the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.75 dl / g, and then the mixture was discharged outside the reactor to form strands, which were solidified with a cooling liquid and then granulated to an average weight of about 12 mg to 14 mg to produce a polyester resin.

[0464]

[0465] Example 4-9

[0466] (a) Preparation of preliminary composition

[0467] In a 10 L reactor connected to a column and a condenser capable of being cooled by water, 3788.8 g of reproduced terephthalic acid (r-TPA), 421.0 g of terephthalic acid (TPA), 7998.6 g of isophthalic acid (IPA), 6441.5 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 3102.7 g of ethylene glycol (EG), 365.2 g of cyclohexanedimethanol (CHDM), 98.7 g of isosorbide (ISB), and diethylene glycol (DEG) prepared in Example 3-9 were charged. 370.3 g was injected. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 2.1, and the molar ratio of r-TPA and TPA was 1:0.11.

[0468] Afterwards, 0.9 g of Ti catalyst, 20.0 g of phosphoric acid as a stabilizer, 1.7 g of cobalt acetate as a coloring agent, and 2000 ppm of a hindered phenol-based oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0469] (b) Esterification reaction

[0470] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 3.0 kgf / cm compared to the atmospheric pressure. 2The reactor was pressurized to a high pressure (absolute pressure: 2966.8 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0471] (c) polycondensation reaction

[0472] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 280°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.60 dl / g, and then the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to have an average weight of about 12 mg to 14 mg.

[0473] (d) solid-state polymerization reaction

[0474] Next, the particles of the above step (c) were left at 150°C for 1 hour to crystallize, and then placed in a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the reactor at a rate of 50 L / min. At this time, the temperature of the reactor was increased from room temperature to 140°C at a rate of 40°C / hour, maintained at 140°C for 3 hours, and then increased to 190°C at a rate of 40°C / hour and maintained at 190°C. The solid-state polymerization reaction was carried out until the intrinsic viscosity (IV) of the particles in the reactor became 1.10 dl / g, thereby producing a polyester resin.

[0475]

[0476] Comparative Example 4-1

[0477] (a) Preparation of preliminary composition

[0478] Into a 10 L reactor connected to a column and a condenser capable of being cooled by water, 2571.8 g of reproduced terephthalic acid (r-TPA), 2571.8 g of terephthalic acid (TPA), 5246.8 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 2134.5 g of ethylene glycol (EG), 148.7 g of cyclohexanedimethanol (CHDM), and 105.5 g of isosorbide (ISB) prepared in Comparative Example 3-1 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.6, and the molar ratio of r-TPA and TPA was 1:1.

[0479] Afterwards, 12.8 g of Ge catalyst was added and stirred to prepare a preliminary composition.

[0480] (b) Esterification reaction

[0481] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 0.5 kgf / cm compared to the atmospheric pressure. 2 The reactor was pressurized to a high pressure (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0482] (c) polycondensation reaction

[0483] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 280°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.50 dl / g, and then the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to have an average weight of about 12 mg to 14 mg.

[0484] (d) solid-state polymerization reaction

[0485] Next, the particles of the above step (c) were left at 150°C for 1 hour to crystallize, and then placed in a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the reactor at a rate of 50 L / min. At this time, the temperature of the reactor was increased from room temperature to 140°C at a rate of 40°C / hour, maintained at 140°C for 3 hours, and then increased to 200°C at a rate of 40°C / hour and maintained at 200°C. The solid-state polymerization reaction was carried out until the intrinsic viscosity (IV) of the particles in the reactor became 0.70 dl / g, thereby producing a polyester resin.

[0486]

[0487] Comparative Example 4-2

[0488] (a) Preparation of preliminary composition

[0489] Into a 10 L reactor connected to a column and a condenser capable of being cooled by water, 825.7 g of reproduced terephthalic acid (r-TPA), 5367.1 g of terephthalic acid (TPA), 3158.6 g of reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), 5746.5 g of ethylene glycol (EG), 716.3 g of cyclohexanedimethanol (CHDM), 193.7 g of isosorbide (ISB), and 72.6 g of diethylene glycol (DEG) prepared in Comparative Example 3-2 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 2.5, and the molar ratio of r-TPA and TPA was 1:6.46.

[0490] Afterwards, 0.4 g of Ti catalyst, 1.7 g of cobalt acetate as a coloring agent, and 10 ppm of a hindered phenol-based oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0491] (b) Esterification reaction

[0492] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 1.0 kgf / cm compared to the atmospheric pressure. 2 The reactor was pressurized to a high pressure (absolute pressure: 1495.6 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 260°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 260°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0493] (c) polycondensation reaction

[0494] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 280°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.70 dl / g, and then the mixture was discharged outside the reactor to be stranded, which was solidified with a cooling liquid and then granulated to have an average weight of about 12 mg to 14 mg.

[0495] (d) solid-state polymerization reaction

[0496] Next, the particles of the above step (c) were left at 150°C for 1 hour to crystallize, and then placed in a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the reactor at a rate of 50 L / min. At this time, the temperature of the reactor was increased from room temperature to 140°C at a rate of 40°C / hour, maintained at 140°C for 3 hours, and then increased to 200°C at a rate of 40°C / hour and maintained at 200°C. The solid-state polymerization reaction was carried out until the intrinsic viscosity (IV) of the particles in the reactor became 0.95 dl / g, thereby producing a polyester resin.

[0497]

[0498] Comparative Example 4-3

[0499] (a) Preparation of preliminary composition

[0500] In a 10 L reactor connected to a column and a condenser capable of being cooled by water, 7098.9 g of reproduced terephthalic acid (r-TPA), 2854.7 g of ethylene glycol (EG), 3079.0 g of cyclohexanedimethanol (CHDM), 83.2 g of isosorbide (ISB), and 62.4 g of diethylene glycol (DEG) prepared in Comparative Example 3-3 were charged. At this time, G / A (total diol / total diacid, molar ratio of glycol component to diacid component) was 1.6.

[0501] Afterwards, 6.4 g of Ge catalyst, 0.1 g of phosphoric acid as a stabilizer, 0.030 g of blue toner, and 0.010 g of red toner were added and stirred to prepare a preliminary composition.

[0502] (b) Esterification reaction

[0503] Next, nitrogen is injected into the reactor containing the preliminary composition of step (a) so that the pressure of the reactor is 0.5 kgf / cm compared to the atmospheric pressure. 2 The reactor was pressurized to a high pressure (absolute pressure: 1127.8 mmHg). Then, the temperature of the reactor was increased from room temperature to 220°C over 90 minutes, maintained at 220°C for 2 hours, and then increased again to 255°C over 2 hours. Thereafter, the esterification reaction was performed at a temperature of 255°C for 3 hours while visually observing the preliminary composition inside the reactor until the preliminary composition became transparent. Upon completion of the esterification reaction, the nitrogen inside the pressurized reactor was purged to the outside to lower the pressure of the reactor to ambient pressure, and the product of the esterification reaction inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0504] (c) polycondensation reaction

[0505] Thereafter, the pressure of the reactor containing the product of the esterification reaction of the above step (b) was reduced from atmospheric pressure to 5.0 Torr (absolute pressure: 5 mmHg) over 30 minutes, and at the same time, the temperature of the reactor was increased to 280°C over 1 hour, and then the pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to perform the polycondensation reaction. At this time, the stirring speed was set to be fast at the beginning of the polycondensation reaction, but as the polycondensation reaction progressed, the stirring force weakened due to the increase in viscosity of the mixture in the reactor, or when the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted accordingly. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) inside the reactor became 0.60 dl / g, and then the mixture was discharged outside the reactor to form strands, which were solidified with a cooling liquid and then granulated to an average weight of about 12 mg to 14 mg to produce a polyester resin.

[0506]

[0507] Experimental Example 3-1: Composition of polyester resin

[0508] The polyester resins of Examples 4-1 to 4-9 and Comparative Examples 4-1 to 4-3 were dissolved in a CDCl3 solvent at a concentration of 3 mg / mL, and the composition (mol%) of the polyester resin was confirmed through a 1H-NMR spectrum obtained using a nuclear magnetic resonance device (JEOL, 600 MHz FT-NMR) at 25°C.

[0509] Example 3-2: Color characteristics

[0510] For the polyester resins of Examples 4-1 to 4-9 and Comparative Examples 4-1 to 4-3, the color characteristics Color L and Color b were measured using a spectrophotometer, and the Color Lb value, which is the difference between the measured Color L value and the Color b value, was calculated.

[0511] Specifically, a 6 mm thick specimen was manufactured using the polyester resin, and data was obtained through transmission mode with Illuminant D65 at an observer angle of 2° using a Varian Cary 5 UV / Vis / NIR spectrophotometer equipped with a diffuse reflection accessory capable of measuring color and brightness, and the Hunter Color L, Color a, and Color b values ​​were calculated by processing the data with a color analysis device within the Grams / 32 software, and the Color Lb value, which is the difference between the Color L value and the Color b value, was calculated.

[0512]

[0513]

[0514]

[0515] As shown in Table 4 above, the polyester resins of Examples 4-1 to 4-9 had excellent color characteristics even though they included recycled terephthalic acid (r-TPA) manufactured from waste polyester. Specifically, the polyester resins of Examples 4-1 to 4-9 had excellent color characteristics due to low pigment residue and yellowness, and also had very low content of metal impurities, thereby exhibiting excellent quality. In particular, Example 2 had excellent color characteristics even though the content of recycled terephthalic acid in the polyester resin was as high as 42 wt% without additional use of terephthalic acid.

Claims

1. Obtained by alcoholysis and hydrolysis of waste polyester. Recycled terephthalic acid having a Color b of less than 2 as measured in the reflectance mode of a spectrophotometer.

2. In paragraph 1, The above recycled terephthalic acid is a recycled terephthalic acid having a total metal content of less than 100 ppm as measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).

3. In paragraph 1, The above-mentioned recycled terephthalic acid is a recycled terephthalic acid having a total content of Sb, Ti and Zn of less than 30 ppm as measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).

4. In paragraph 1, The above regenerated terephthalic acid is obtained through a purification process, and has a pigment residue of 10% or less according to the following formula 1: [Formula 1] In the above equation 1, B1 is the area of the absorbance curve obtained from 400 nm to 800 nm using a UV-vis spectrophotometer after diluting the above-mentioned regenerated terephthalic acid to a concentration of 5% in dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), or methyl pyrrolidone (NMP), B2 is the area of the absorbance curve obtained by the same method as above for regenerated terephthalic acid manufactured through the same process as the manufacturing process of the above regenerated terephthalic acid, but without performing a purification process.

5. In paragraph 1, Regenerated terephthalic acid, wherein the above-mentioned regenerated terephthalic acid is diluted to a concentration of 5% using dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), or methyl pyrrolidone (NMP), and the yellowness index (YI) measured by a colorimeter is less than 2.

6. Contains recycled terephthalic acid obtained by alcoholylysis and hydrolysis of waste polyester and having a Color b of less than 2 measured in the reflection mode of a spectrophotometer. A polyester resin having a difference between the Color L value and the Color b value (Color L - Color b) measured in the transmission mode of a spectrophotometer for a 6 mm thick specimen exceeding 83.

7. In paragraph 6, A polyester resin, wherein the content of the above-mentioned recycled terephthalic acid is 0.1 wt% to 55 wt% based on the total weight of the polyester resin.

8. In paragraph 6, The above polyester resin contains a diacid component and a glycol component, The above-mentioned diacid components are terephthalic acid (TPA), isophthalic acid (IPA), dimethyl isophthalate, bis(2-hydroxyethyl) terephthalate, reproduced bis(2-hydroxyethyl) terephthalate (r-BHET), phthalic acid, dimethyl phthalate, phthalic anhydride, 2,6-naphthalene dicarboxylic acid, dimethyl 2,6-naphthalene dicarboxylate, diphenyl dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, dimethyl 1,4-cyclohexane dicarboxylate, dimethyl 1,3-cyclohexane dicarboxylate, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, fumaric acid, Containing at least one selected from the group consisting of adipic acid, glutaric acid and azelaic acid; The above glycol components are isosorbide (ISB), regenerated isosorbide (r-ISB), ethylene glycol (EG), regenerated ethylene glycol (r-EG), 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, cyclohexanedimethanol (CHDM) and derivatives thereof, regenerated A polyester resin comprising at least one selected from the group consisting of cyclohexanedimethanol (r-CHDM), diethylene glycol (DEG), recycled diethylene glycol (r-DEG), neopentyl glycol (NPG), and recycled neopentyl glycol (r-NPG).

9. In paragraph 8, A polyester resin wherein the molar ratio of the above-mentioned regenerated terephthalic acid and the above-mentioned diacid component is 1:0.01 to 3.

5.

10. In paragraph 6, The above polyester resin is a polyester resin having an intrinsic viscosity (IV) of 0.5 dl / g to 1.3 dl / g.

11. An article comprising a polyester resin according to Article 6.

12. A step of producing recycled terephthalic acid by alcoholylysis and hydrolysis of waste polyester; A step of preparing a preliminary composition by mixing the above-mentioned recycled terephthalic acid with a glycol component; A step of esterifying the above-mentioned preliminary composition; and Comprising a step of subjecting the above esterification reaction product to a polycondensation reaction, A method for producing a polyester resin, wherein the above-mentioned recycled terephthalic acid has a Color b value of less than 2 as measured in a reflection mode of a spectrophotometer.

13. In paragraph 12, A method for producing a polyester resin, wherein a diacid component is additionally mixed in the step of producing the above-mentioned preliminary composition.

14. In paragraph 12, The step of manufacturing the above regenerated terephthalic acid is: (1) a step of producing a liquid composition including a compound represented by the following chemical formula 1 by alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms; and (2) A method for producing a polyester resin, comprising a step of hydrolyzing the liquid composition: [Chemical Formula 1] In the above chemical formula 1, R1 is alkyl having 4 or more carbon atoms.

15. In paragraph 14, A method for producing a polyester resin, wherein the alcohol has 4 to 14 carbon atoms.

16. In paragraph 14, A method for producing a polyester resin, further comprising a step of purifying the liquid composition prior to the step (2).

17. In paragraph 16, The above purifying step includes a step of introducing at least one adsorbent selected from the group consisting of activated carbon, silica gel, alumina, zeolite and activated clay or adsorbing through bed adsorption, A method for producing a polyester resin, wherein the amount of the adsorbent added is 0.1 wt% to 20 wt% based on the total weight of the liquid composition.

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