Method for producing polyester resin and polyester resin produced thereby

Abstract

The present invention relates to a polyester resin and a method for producing same, the method comprising: (1) a step for obtaining a liquid raw material including a compound represented by chemical formula 1 by the alcoholysis of waste polyester using an alcohol having 4 or more carbon atoms; (2) a step for obtaining a product by subjecting a preliminary composition including the liquid raw material to an esterification reaction; and (3) a step for subjecting the product to a polycondensation reaction. According to the present invention, a polyester resin of high quality can be economically produced.

Description

Method for producing polyester resin and polyester resin produced therefrom

[0001] The present invention relates to a method for producing a polyester resin capable of economically producing a high-quality polyester resin by decomposing (depolymerizing) waste polyester to obtain an intermediate and using this as a polymerization raw material (recycled raw material), and to a polyester resin produced from the method.

[0002] Among polymer types, polyester resins are widely used as materials for beverage or food containers; various packaging films or sheets; and various interior and exterior materials such as panels, shelves, and partitions.

[0003] Due to the widespread use of polyester, the annual global volume of polyester waste with polyester resin applied to it is becoming increasingly unmanageable. Consequently, interest in recycling waste polyester or regeneration processes utilizing it is growing. Specifically, development is underway for processes that decompose (depolymerize) waste polyester to produce polymerization raw materials (recycled raw materials), and further utilize these polymerization raw materials to produce polyester resin (recycled polyester resin).

[0004] In the past, a hydrolysis process using an alkaline aqueous solution or water was performed to decompose the waste polyester and produce a polymerization raw material. However, when the hydrolysis process is performed, an additional neutralization process using acid is required, which causes problems such as the generation of environmental pollutants as byproducts or the generation of a large amount of acid-treated wastewater. In addition, the equipment for performing the hydrolysis process is expensive, which limits the ability to increase the recyclability of waste polyester. In addition, the polymerization raw material obtained by decomposing the waste polyester does not have a high purity, so when using it to produce a polyester resin, there is a problem that the quality (e.g., color characteristics) of the polyester resin is reduced.

[0005] Therefore, there is a need for a technology that can economically manufacture high-quality polyester resin by improving the recycling process of waste polyester.

[0006] [Prior Art Literature]

[0007] [Patent Document]

[0008] (Patent Document 1) Republic of Korea Publication Patent No. 2022-0024095

[0009] The present inventors have confirmed that when a specific alcohol is introduced into the decomposition (depolymerization) reaction of waste polyester to obtain a polymerization raw material (recycled raw material) and this is directly used to manufacture a polyester resin, a high-quality polyester resin can be obtained while omitting the conventional hydrolysis process.

[0010] Accordingly, the object of the present invention is to provide a method for producing a polyester resin capable of economically producing a high-quality polyester resin and a polyester resin produced from the method.

[0011] In order to solve the above problem, the present invention provides a method for producing a polyester resin, comprising the steps of: (1) alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms to obtain a liquid raw material containing a compound represented by the following chemical formula 1; (2) subjecting a preliminary composition containing the liquid raw material to an esterification reaction to obtain a product; and (3) subjecting the product to a polycondensation reaction.

[0012] [Chemical Formula 1]

[0013]

[0014] In the above chemical formula 1,

[0015] R1 is alkyl having 4 or more carbon atoms.

[0016] In addition, the present invention provides a polyester resin manufactured from the above manufacturing method.

[0017] The method for producing a polyester resin according to the present invention obtains a liquid raw material by alcoholyzing waste polyester with a specific alcohol, and directly applies the liquid raw material as a polymerization raw material of a polyester resin without hydrolyzing it, thereby producing a polyester resin, thereby making it possible to economically produce a polyester resin having high quality (e.g., excellent color characteristics).

[0018] Specifically, the present invention manufactures a specific liquid raw material including a compound represented by Chemical Formula 1 by introducing an alcohol having 4 or more carbon atoms into the alcoholysis reaction of waste polyester, and directly applies the same as a polymerization raw material of a polyester resin without a hydrolysis or hydrolysis and neutralization process, thereby manufacturing a polyester resin, thereby achieving simplification of the manufacturing process of the polyester resin and reduction of process costs (for example, omission of a hydrolysis process requiring expensive equipment).

[0019] In addition, since the present invention obtains a liquid raw material (intermediate) that is in a liquid state rather than a solid state through an alcoholysis reaction, impurities such as a metal catalyst and a coloring pigment contained therein can be easily removed, thereby improving the color characteristics of the final product, a polyester resin.

[0020] Hereinafter, the present invention will be described in detail. Herein, the present invention is not limited to the contents described below, and may be modified in various forms as long as the gist of the invention is not changed.

[0021] The word "comprising" or "including" in this specification is intended to specify particular features, regions, steps, processes, elements and / or components, and does not exclude the presence or addition of other features, regions, steps, processes, elements and / or components, unless specifically stated to the contrary.

[0022] All numbers and expressions indicating the amounts of components, reaction conditions, etc. described in this specification can be understood to be modified by the term “about” in all cases unless otherwise specified.

[0023] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0024]

[0025] The present invention is characterized by producing a polyester resin by decomposing (depolymerizing) waste polyester to obtain a liquid intermediate, which is then directly introduced into a polyester resin polymerization process without further decomposition (e.g., hydrolysis) or neutralization. The present invention will be described in detail as follows.

[0026]

[0027] Method for manufacturing polyester resin

[0028] A method for producing a polyester resin according to the present invention comprises: (1) a step of alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms to obtain a liquid raw material containing a compound represented by the following chemical formula 1; (2) a step of subjecting a preliminary composition containing the liquid raw material to an esterification reaction to obtain a product; and (3) a step of subjecting the product to a polycondensation reaction.

[0029] [Chemical Formula 1]

[0030]

[0031] In the above chemical formula 1,

[0032] R1 is alkyl having 4 or more carbon atoms.

[0033]

[0034] Step (1): Obtaining liquid raw materials

[0035] According to the present invention, step (1) is a step of alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms to obtain a liquid raw material containing a compound represented by the chemical formula 1. Through the alcoholysis, a liquid raw material having a liquid phase rather than a solid phase and containing a high content of a compound represented by the chemical formula 1 suitable as a polymerization raw material component of a polyester resin is obtained, thereby making it possible to economically produce a polyester resin having high quality.

[0036] Specifically, even if a solid oligomer or the like is generated as a by-product in the alcoholysis process, since the compound represented by the chemical formula 1 or the like has a liquid phase and the oligomer exists in the liquid raw material in a dissolved state, the polyester resin can be manufactured (polymerized) directly using the liquid raw material without adding a separate substance for dissolving the oligomer or without a process / equipment for this purpose. In addition, since ethylene glycol, diethylene glycol, and the like generated as by-products in the alcoholysis process can be easily removed, a high-quality polyester resin can be manufactured.

[0037] The above waste polyester may be a waste polyester product, or a product obtained by crushing or melting waste. Specifically, the waste polyester may include at least one selected from the group consisting of waste polyethylene terephthalate fibers, waste polyethylene terephthalate containers, waste polyethylene terephthalate films, and polyester waste (Post Industrial Recycled material; PIR), and may be a product obtained by crushing the same or converting the same into a pellet form. The above polyester waste (PIR) may refer to defective products or scraps generated during the molding process of films, fibers, containers, etc.

[0038] Considering the quality and properties of the final polyester resin, the waste polyester may contain polyethylene terephthalate (PET) in an amount of 50 wt% or more, and specifically, 55 wt% or more, 60 wt% or more, 65 wt% or more, 70 wt% or more, 75 wt% or more, 80 wt% or more, 85 wt% or more, 90 wt% or more, or 95 wt% or more (e.g., 50 to 100 wt%, 60 to 97 wt%, 70 to 95 wt%, or 80 to 90 wt%), based on the total weight of the waste polyester.

[0039] The alcohol used in the alcoholysis reaction may have a carbon number of 4 or more, 6 or more, 8 or more, 10 or more, 12 or more, or 14 or more. Specifically, the alcohol may have a carbon number of 4 to 13, 4 to 12, 4 to 10, 4 to 8, 4 to 7, or 4 to 6. By performing alcoholysis of waste polyester using an alcohol having the above carbon number, alcoholysis can be performed at a relatively lower temperature and pressure than in the past, and a liquid raw material containing only liquid components and no solid components can be obtained. In addition, the reaction rate of the alcoholysis can be increased.

[0040] The boiling point of the alcohol may be 100 to 290°C, and specifically, 110 to 280°C, 120 to 260°C, 130 to 230°C, 140 to 190°C, or 150 to 180°C. Since the boiling point of the alcohol is within the above range, by-products such as ethylene glycol and diethylene glycol generated in the alcoholysis process can be more easily removed or recovered in a subsequent process, thereby improving processability.

[0041] The reaction ratio of the waste polyester and the alcohol for the above alcohol decomposition is not particularly limited, but may be a weight ratio of 1:1 to 10. Specifically, the weight ratio 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.

[0042] Through the alcoholysis, a liquid raw material containing a high content of the compound represented by the chemical formula 1 is produced. Specifically, the liquid raw material may contain 45 to 99.9 mol% of the compound represented by the chemical formula 1 based on the total mole number of the liquid raw material. For example, the content of the compound represented by the chemical formula 1 may be 50 to 99.9 mol%, 55 to 99.5 mol%, 60 to 99.5 mol%, 65 to 99 mol%, 68 to 99 mol%, 70 to 98 mol%, 73 to 97 mol%, 75 to 96 mol%, 78 to 95 mol%, 80 to 93 mol%, 83 to 92 mol%, or 85 to 90 mol% based on the total mole number of the liquid raw material. When the content of the compound represented by the above chemical formula 1 is within the above range, even if the liquid raw material is directly applied as a polymerization raw material of a polyester resin, a polyester resin of excellent quality can be manufactured with high efficiency.

[0043] In the compound represented by the above chemical formula 1, R1 is specifically, 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, It can be 4-methylhexyl, 5-methylhexyl, decanyl, undecanyl, dodecanyl, tridecanyl or tetradecanyl.

[0044] According to the present invention, the alcoholysis can be carried out at a temperature of 160 to 280°C for 0.5 to 24 hours. Specifically, the alcoholysis reaction can be carried out at a temperature of 165 to 270°C, 170 to 260°C, 175 to 250°C, 180 to 240°C, or 180 to 230°C for 1 to 22 hours, 1.5 to 20 hours, 2 to 15 hours, 2.5 to 10 hours, 3 to 8 hours, or 3 to 6 hours. Meanwhile, the alcoholysis can be carried out at a reaction pressure set according to the reaction temperature and / or reaction time. Specifically, the pressure during the alcoholysis reaction may be 1 to 40 bar, 1 to 38 bar, 1.5 to 33 bar, 2 to 28 bar, 2.5 to 24 bar, 3 to 40 bar, 4 to 35 bar, or 5 to 30 bar.

[0045] The above alcoholysis reaction may or may not involve a catalyst. If the alcoholysis reaction is a non-catalytic reaction in which a catalyst is not introduced, the removal process for insoluble metals, etc. can be omitted, thereby ensuring environmental friendliness and producing a high-purity polyester resin. Furthermore, if the alcoholysis reaction is a catalytic reaction in which a catalyst is introduced, the activity of the alcoholysis reaction can be increased, thereby improving processability (economic feasibility).

[0046] As a catalyst to be used in the above alcohol decomposition reaction, metal acetate salts, alkali metal salts, hydroxyl salts, etc. may be used. Specifically, the catalyst may be Li + , Na + , K + , or Cs + Alkali metal ions, Be 2+ , Mg 2+ , Ca 2+ , or Ba 2+ Alkaline earth metal ions, NH 4+ , and Zn 2+One or more cations selected from the group consisting of; and / or OH - , OR - , 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.

[0047] For example, the catalyst may include at least one selected from the group consisting of Zn(OAC)2, Co(OAc)2, Mn(OAc)2, Mg(OAc)2, Ca(OAc)2, Pb(OAc)2, Ba(OAc)2, LiOAc, NaOAc, KOAc, Pd(OAc)2, Zn(OAC)2·2H2O, Co(OAc)2·4H2O, Mn(OAc)2·4H2O, Mg(OAc)2·4H2O, Ti(OBu)4, Ti(OiPr)4, GeO2, Al(OiPr)3, Na2CO3, K2CO3, dibutyltin(IV) oxide, tin octoate, titanium phosphate, and terephthalic acid.

[0048] The amount of the catalyst added may be 10 to 10,000 ppm, 10 to 9,000 ppm, 15 to 8,000 ppm, 20 to 6,000 ppm, 50 to 3,500 ppm, 100 to 1,500 ppm, 150 to 1,000 ppm, 180 to 500 ppm, or 200 to 450 ppm, based on the total weight of the waste polyester.

[0049] Meanwhile, the liquid raw material may further include at least one selected from the group consisting of alcohol derivatives and oligomers. Specifically, the liquid raw material may include the alcohol derivative and not the oligomer, or may not include the alcohol derivative and may include the oligomer, or may include both the alcohol derivative and the oligomer. The alcohol derivative and / or the oligomer may exist in a liquid state in the liquid raw material, and thus, the production (polymerization) of the polyester resin may proceed without going through a process such as hydrolysis of the liquid raw material.

[0050] Specifically, the present invention may not include a step of hydrolyzing the liquid raw material. That is, in the past, a product obtained through an alcoholysis reaction was hydrolyzed to obtain a solid polymerization raw material (e.g., terephthalic acid), which was then applied as a polymerization raw material for a polyester resin. However, the present invention can directly apply the liquid raw material as a polymerization raw material for a polyester resin without going through the hydrolysis step, thereby achieving simplification of the manufacturing process for a polyester resin and reduction of process costs (e.g., omission of a hydrolysis process requiring expensive equipment).

[0051] The content of each of the alcohol derivative and the oligomer included in the liquid raw material may not be particularly limited. Specifically, the liquid raw material may contain 0.01 to 50 mol% of the alcohol derivative and 0.01 to 50 mol% of the oligomer, based on the total mole number of the liquid raw material. For example, the content of the alcohol derivative may be 0.1 to 40 mol%, 0.1 to 35 mol%, 0.5 to 30 mol%, 0.5 to 25 mol%, 1 to 23 mol%, 1 to 22 mol%, 1.5 to 21 mol%, 1.5 to 20 mol%, 2 to 18 mol%, 2.5 to 17 mol%, 3 to 15 mol%, or 5 to 10 mol%, based on the total mole number of the liquid raw material. In addition, the content of the oligomer may be 0.05 to 40 mol%, 0.05 to 35 mol%, 0.1 to 30 mol%, 0.1 to 25 mol%, 0.5 to 20 mol%, 0.5 to 15 mol%, 1 to 10 mol%, 1 to 8 mol%, 1.5 to 5 mol%, 1.5 to 4 mol%, 2 to 4 mol%, or 2 to 3 mol%, based on the total mole number of the liquid raw material. When the contents of the alcohol derivative and the oligomer are each within the above range, even if the liquid raw material is directly applied as a polymerization raw material of a polyester resin, a polyester resin having excellent quality can be manufactured with high efficiency.

[0052] According to the present invention, the alcohol derivative 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. Since the alcohol derivative and the oligomer each include the following compounds, the quality and manufacturing efficiency (polymerization efficiency) of the final product, a polyester resin, can be improved.

[0053] [Chemical Formula 2]

[0054]

[0055] [Chemical Formula 3]

[0056]

[0057] In the above chemical formulas 2 and 3,

[0058] R2 and R3 are each independently an alkyl having 4 or more carbon atoms, and n is an integer of 1 or more.

[0059] Specifically, in the compounds represented by the above chemical formulas 2 and 3, R2 and R3 are each independently an alkyl having 4 to 12 carbon atoms, and n may be an integer of 1 to 3.

[0060] Meanwhile, according to the present invention, the liquid raw material may further include at least one selected from the group consisting of ethylene glycol and unreacted alcohol. Specifically, the liquid raw material may include the ethylene glycol and not the unreacted alcohol, or may not include the ethylene glycol and may include the unreacted alcohol, or may include both the ethylene glycol and the unreacted alcohol.

[0061] The above ethylene glycol may refer to a by-product produced by the alcoholysis reaction, and the unreacted alcohol may refer to residual alcohol remaining after the alcohol having 4 or more carbon atoms introduced for the alcoholysis reaction does not participate in the alcoholysis reaction. Since the liquid raw material includes the ethylene glycol, the amount of ethylene glycol that must be introduced separately when the esterification reaction for polymerization of the polyester resin is performed can be reduced, thereby improving the processability (economic feasibility) of the polyester resin.

[0062] The content of the unreacted alcohol contained in the liquid raw material may not be particularly limited. Specifically, the liquid raw material may contain 0.01 to 50 mol% of the unreacted alcohol based on the total mole number of the liquid raw material. For example, the content of the unreacted alcohol may be 0.01 to 40 mol%, 0.01 to 35 mol%, 0.01 to 30 mol%, 0.02 to 25 mol%, 0.02 to 20 mol%, 0.02 to 15 mol%, 0.03 to 10 mol%, 0.03 to 5 mol%, 0.03 to 1 mol%, 0.04 to 0.5 mol%, 0.04 to 0.1 mol%, or 0.05 to 0.07 mol% based on the total mole number of the liquid raw material. When the content of the unreacted alcohol is within the above range, the content of ethylene glycol added during the esterification reaction for polymerization can be minimized while improving the polymerization reaction speed of the polyester resin.

[0063] In addition, the liquid raw material may not contain ethylene glycol and unreacted alcohol. Specifically, the liquid raw material may optionally undergo further steps of fractional distillation, adsorption purification, and concentration, which will be described later, before being introduced into the esterification reaction, thereby removing (or recovering) ethylene glycol and unreacted alcohol and thus not containing ethylene glycol and unreacted alcohol (for example, the content of each of ethylene glycol and unreacted alcohol is 0 mol%). For example, the liquid raw material may not contain unreacted alcohol (for example, butanol) in order to significantly increase the polymerization reaction rate of the polyester resin while obtaining a high-quality polyester resin.

[0064] That is, according to the present invention, the manufacturing method may further include a step of fractional distillation of the liquid raw material prior to the esterification reaction. The fractional distillation may be performed by a commonly known fractional distillation method, through which unreacted alcohol and ethylene glycol, a by-product, can be removed and recovered. At this time, the recovered unreacted alcohol is reused as a raw material for the alcoholysis reaction, and the ethylene glycol can be reused as a raw material for polymerization of a polyester resin or utilized in another process, thereby ensuring processability (economic feasibility). Meanwhile, by-products such as diethylene glycol can also be removed through the fractional distillation, and as a result, impurity components derived from diethylene glycol, etc., do not exist in the final polyester resin, thereby producing a high-quality polyester resin.

[0065] Additionally, according to the present invention, the manufacturing method may further include a step of adsorbing and purifying the liquid raw material prior to the esterification reaction. Specifically, the adsorbing purification may be performed using one or more adsorbents selected from the group consisting of activated carbon, silica gel, alumina, zeolite, and activated clay, or through bed adsorption.

[0066] The above adsorbent may be specifically activated carbon or a mixture of activated carbon and silica gel. 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.

[0067] The amount of the adsorbent added is not particularly limited, but may be 0.1 to 20 wt%, 0.1 to 18 wt%, 0.2 to 15 wt%, 0.2 to 10 wt%, 0.3 to 5 wt%, or 0.3 to 2 wt% based on the total weight of the liquid raw material. By adding the adsorbent to the liquid raw material in the above amount and performing adsorption purification, insoluble impurities such as metals, or impurities such as colorants and pigments derived from waste polyester can be effectively removed, thereby producing a polyester resin with excellent purity and quality.

[0068] Additionally, according to the present invention, the manufacturing method may further include a step of concentrating the liquid raw material prior to the esterification reaction. Specifically, the step of concentrating the liquid raw material may be further performed after the adsorption purification. The concentration may be performed using a conventionally known concentration method, thereby removing and recovering unreacted alcohol and ethylene glycol, a byproduct.

[0069] Specifically, the concentration can be performed by stirring and filtering the adsorption-purified liquid raw material at a temperature of 55 to 115°C, 60 to 110°C, 65 to 105°C, or 75 to 100°C for 1 to 5 hours, 1.5 to 4 hours, or 2 to 4 hours.

[0070] The liquid raw material that has undergone the above adsorption purification may have a pigment residue rate (%) according to the following formula A of 15% or less, 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.

[0071] [Formula A]

[0072]

[0073] In the above formula A,

[0074] A1 is the area of ​​the absorbance curve obtained at 400 to 800 nm using a UV-vis spectrophotometer after diluting the adsorption-purified liquid raw material to a concentration of 5% using dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or methylpyrrolidone (NMP), respectively.

[0075] A2 is the area of ​​the absorbance curve obtained by the same method as above for a liquid raw material that has not undergone adsorption purification.

[0076] The liquid raw material obtained in this way has a very small amount of impurities and is in a liquid state, so it can be efficiently used as a polymerization raw material in the esterification reaction step, which is the step for starting polymerization of a polyester resin.

[0077]

[0078] Step (2): Esterification reaction

[0079] According to the present invention, step (2) is a step of obtaining a product by subjecting a preliminary composition including the liquid raw material to an esterification reaction.

[0080] The above-mentioned preliminary composition may include a diol component that undergoes an esterification reaction with the above-mentioned liquid raw material. The diol component is not particularly limited as long as it is commonly known, and specifically may include at least one selected from the group consisting of ethylene glycol, cyclohexanedimethanol, isosorbide, neopentyl glycol, 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, 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, and diethylene glycol. Among the above diol components, the ethylene glycol may be derived from the alcoholysis reaction described above or may be supplied separately and added to the esterification reaction.

[0081] In addition, the above-described preliminary composition may further comprise a commonly known dicarboxylic acid component. Specifically, the dicarboxylic acid component may comprise at least one selected from the group consisting of terephthalic acid, dimethylterephthalic acid, isophthalic acid, dimethylterephthalate, 1,4-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, dimethyl 1,4-cyclohexane dicarboxylate, dimethyl 1,3-cyclohexane dicarboxylate, 2,6-naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbene dicarboxylic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid.

[0082] In addition, the above-mentioned preliminary composition may further include one or more additives selected from the group consisting of commonly known oxidation stabilizers, branching agents, coloring agents, crystallizers, catalysts, stabilizers, and ultraviolet absorbers.

[0083] The above-mentioned oxidation stabilizer is not particularly limited, but may include at least one selected from the group consisting of hindered phenol compounds, phosphite compounds, and thioether compounds.

[0084] The branching agent may be a compound having three or more functional groups, and specifically may include at least one selected from the group consisting of trimellitic anhydride, trimellitic acid, pyromelletic dianhydride, glycerol, trimethylol propane, pentaerythritol, citric acid, tartaric acid, and 3-hydroxyglutaric acid.

[0085] The coloring agent is not particularly limited, but may include at least one selected from the group consisting of cobalt compounds, anthraquionone compounds, perinone compounds, azo compounds, and methine compounds. Specifically, cobalt acetate, cobalt propionate, Clarient's Polysynthren Blue RLS toner, Clarient's Solvaperm Red BB toner, etc. may be used as the coloring agent.

[0086] The catalyst is not particularly limited, but may include methylates of sodium and magnesium; acetates, borates, fatty acid salts, or carbonates of Zn, Cd, Mn, Co, Ca, Ba, etc.; or oxides or hydrates of Mg, Pb, Mn, Ti, Sb, Sn, Al, Ge, etc. Specifically, the catalyst may include tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, triethanolamine titanate, acetylacetonate titanate, ethylacetoacetic ester titanate, isostearyl titanate, titanium dioxide, germanium dioxide, germanium tetrachloride, germanium ethylene glycoside, germanium acetate, or a combination thereof.

[0087] The above stabilizer is not particularly limited, but may include phosphorus compounds such as phosphoric acid, trimethyl phosphate, and triethyl phosphate.

[0088] The conditions under which the esterification reaction is performed may not be particularly limited. Specifically, the esterification reaction temperature may be 200 to 300°C, 230 to 300°C, 250 to 300°C, or 250 to 280°C. In addition, the esterification reaction pressure may be from atmospheric pressure to 3 bar, or from atmospheric pressure to 2 bar. As the esterification reaction is performed under the above conditions, a product having a desired molecular weight can be obtained in high yield while minimizing the production of side products.

[0089]

[0090] Step (3): Polycondensation reaction

[0091] According to the present invention, step (3) is a step of subjecting the product to a polycondensation reaction. The conditions under which the polycondensation reaction is performed may not be particularly limited. Specifically, the polycondensation reaction temperature may be 200 to 300°C, 230 to 300°C, 250 to 300°C, or 250 to 280°C. In addition, the esterification reaction pressure may be 10 -2 10 inland 3 Torr, 10 -1 10 inland 1 Torr, or 0 to 1 Torr. When the polycondensation reaction is performed under the above conditions, a polyester resin (polymer) having crystallinity and excellent quality (e.g., color, etc.) can be efficiently manufactured.

[0092]

[0093] Meanwhile, the method for producing a polyester resin according to the present invention may further include a step of subjecting the polymer obtained through the polycondensation reaction of step (3) to a solid-state polymerization reaction, if necessary, in order to control the intrinsic viscosity (IV), molecular weight, etc. of the polymer. The solid-state polymerization reaction conditions are not particularly limited and may be appropriately set depending on the intrinsic viscosity, molecular weight, etc. of the desired polyester resin.

[0094]

[0095] polyester resin

[0096] The present invention provides a polyester resin manufactured from the polyester resin described above. Since the polyester resin is manufactured using the manufacturing method described above, it can exhibit high quality while also exhibiting improved processability (economic efficiency).

[0097] Specifically, according to the present invention, the polyester resin may have excellent color characteristics. For example, the polyester resin may have a difference (Color Lb) between the Color L value and the Color b value measured using a spectrophotometer of 85 or more, and specifically, 86 or more, 87 or more, 88 or more, 89 or more, 90 or more, 91 or more, 92 or more, 93 or more, 94 or more, or 95 or more (e.g., 85 to 99, 86 to 97, or 88 to 95).

[0098] Meanwhile, the intrinsic viscosity of the polyester resin is not particularly limited, but the melt intrinsic viscosity may be 0.64 to 0.78 dl / g, 0.64 to 0.77 dl / g, 0.65 to 0.77 dl / g, 0.65 to 0.76 dl / g, 0.66 to 0.75 dl / g, or 0.68 to 0.74 dl / g, and the solid intrinsic viscosity may be 0.95 to 1.50 dl / g, 0.97 to 1.45 dl / g, 0.99 to 1.40 dl / g, 1.00 to 1.35 dl / g, or 1.10 to 1.30 dl / g. As the intrinsic viscosity of the polyester resin is within the above range, an article having the desired properties can be manufactured while ensuring the formability of the polyester resin.

[0099] The above polyester resin may be in the form of chips, pellets, or powder (particles).

[0100] Additionally, the polyester resin may be a homopolymer or a copolymer.

[0101] These polyester resins can be used in a molding process to manufacture articles having various shapes and uses. The method for molding the polyester resin to manufacture the articles is not particularly limited, as long as it is a commonly known method. Specific examples include injection molding, extrusion molding, pressure molding, vacuum molding, and blow molding. The articles may be containers, films, sheets, or interior and exterior materials.

[0102]

[0103] The present invention is described in more detail through the following examples. However, the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention.

[0104]

[0105] <Manufacturing of liquid raw materials through alcohol decomposition>

[0106] [Example 1-1]

[0107] 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 relative to the total weight of the waste PET) as an alcoholysis catalyst was added.

[0108] 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 while maintaining the temperature at 250°C and the pressure at 24 bar for 3 hours.

[0109] After the above alcoholysis reaction was completed, the mixture was cooled to room temperature to obtain a liquid raw material. The components and their contents of the obtained liquid raw material were analyzed via NMR, and as a result, it was confirmed that it contained a compound in which R1 is (CH2)3CH3, residual ethylene glycol (EG), unreacted 1-butanol, alcohol derivatives, and oligomers.

[0110] Afterwards, the above liquid raw material was placed in a separate flask, and the excess unreacted 1-butanol and residual ethylene glycol (EG) were recovered using a fractional distillation device.

[0111]

[0112] [Example 1-2]

[0113] 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 relative to the total weight of the waste PET) as an alcoholysis catalyst was added.

[0114] 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 continuously performed by stirring while maintaining the temperature at 250°C and the pressure at 24 bar for 3 hours.

[0115] 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) produced during the alcoholysis reaction and unreacted 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 discharged through the back pressure regulator was condensed using an external cooling device. The discharge rate of the gaseous mixture 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 discharged gaseous mixture. The alcoholysis reaction was performed while maintaining the discharge and supply processes for 3 hours.

[0116] After the above alcoholysis reaction was completed, the mixture was cooled to room temperature to obtain a liquid raw material. The components and their contents of the obtained liquid raw material were analyzed via NMR, and as a result, it was confirmed that it contained a compound in which R1 is (CH2)3CH3, residual ethylene glycol (EG), unreacted 1-butanol, alcohol derivatives, and oligomers.

[0117] Afterwards, the above liquid raw material was placed in a separate flask, and the excess unreacted 1-butanol and residual ethylene glycol (EG) were recovered using a fractional distillation device.

[0118]

[0119]

[0120] [Example 1-3]

[0121] A liquid raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-pentanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 13 bar.

[0122]

[0123] [Example 1-4]

[0124] A liquid raw material was prepared in the same manner as in Example 1-2, except that 3.3 kg of 1-pentanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 13 bar.

[0125]

[0126] [Example 1-5]

[0127] A liquid raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-octanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 3.4 bar.

[0128]

[0129] [Example 1-6]

[0130] A liquid raw material was prepared in the same manner as in Example 1-2, except that 3.3 kg of 1-octanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 3.4 bar.

[0131]

[0132] [Example 1-7]

[0133] A liquid raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of 2-ethyl-1-hexanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 4.1 bar.

[0134]

[0135] [Example 1-8]

[0136] A liquid raw material was prepared in the same manner as in Example 1-2, except that 3.3 kg of 2-ethyl-1-hexanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 4.1 bar.

[0137]

[0138] [Example 1-9]

[0139] A liquid raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-decanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 1.6 bar.

[0140]

[0141] [Example 1-10]

[0142] A liquid raw material was prepared in the same manner as in Example 1-2, except that 3.3 kg of 1-decanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 1.6 bar.

[0143]

[0144] [Example 1-11]

[0145] A liquid raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of 1-dodecanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 1.0 bar.

[0146]

[0147] [Example 1-12]

[0148] 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 relative to the total weight of the waste PET) as an alcohol decomposition catalyst was added.

[0149] 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 continuously performed by stirring while maintaining the temperature at 250°C and the pressure at 1.0 bar for 3 hours.

[0150] 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 vapor of ethylene glycol (EG) (EG vapor) generated during the alcoholysis reaction. At this time, the internal temperature of the first high-pressure reactor was continuously maintained at 250°C, and the vapor discharged through the back pressure regulator was condensed using an external cooling device. 1-Dodecanol was continuously supplied to the first high-pressure reactor in an amount equal to the amount of ethylene glycol (EG) condensed as the vapor. At this time, the capacity and input speed of 1-dodecanol newly supplied to the first high-pressure reactor were adjusted to be the same as the capacity and discharge speed of the vapor. The alcoholysis reaction was performed while maintaining the discharge and supply processes for 3 hours.

[0151] After the above alcoholysis reaction was completed, it was cooled to room temperature to obtain a liquid raw material. The obtained liquid raw material was analyzed for its components and contents through NMR, and as a result, R1 was (CH2) 11 It was confirmed that the compound contained CH3, residual ethylene glycol (EG), unreacted 1-butanol, and alcohol derivatives.

[0152] Thereafter, the above liquid raw material was placed in a separate flask, and an excess of unreacted 1-dodecanol and residual ethylene glycol (EG) were recovered using a fractional distillation device.

[0153]

[0154] [Comparative Example 1-1]

[0155] The raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of methanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 83 bar.

[0156]

[0157] [Comparative Example 1-2]

[0158] The raw material was prepared in the same manner as in Example 1-2, except that 3.3 kg of methanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 83 bar.

[0159]

[0160] [Comparative Example 1-3]

[0161] The raw material was prepared in the same manner as in Example 1-1, except that 3.3 kg of ethanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 64 bar.

[0162]

[0163] [Comparative Example 1-4]

[0164] The raw material was prepared in the same manner as in Example 1-2, except that 3.3 kg of ethanol was used as alcohol and the pressure of the first high-pressure reactor was maintained at 64 bar.

[0165]

[0166] [Example 1]

[0167] In the examples and comparative examples, the components and their contents were analyzed through NMR for the liquid raw materials from which unreacted alcohol and residual ethylene glycol (EG) were recovered through a fractional distillation device, and the results are shown in Table 1 below.

[0168]

[0169] Composition of alcohol liquid raw material Compound represented by chemical formula 1 Alcohol derivative (R1 = R2) content (mol %) Oligomer (R1 = R3) content (mol %) R1 content (mol %) Example 1-11-butanol-(CH2)3CH387121 Example 1-29361 Example 1-31-pentanol-(CH2)4CH384142 Example 1-49451 Example 1-51-octanol-(CH2)7CH378184 Example 1-69910 Example 1-72-ethyl-1-hexanol 77176 Example 1-89910 Example 1-91-decanol-(CH2)9CH373198 Example 1-109910 Example 1-111-dodecanol-(CH2) 11 CH371209Example 1-129910Comparative Example 1-1methanol-CH39181Comparative Example 1-2methanol-CH39271Comparative Example 1-3ethanol-CH2CH39091Comparative Example 1-4ethanol-CH2CH39361

[0170] Referring to Table 1 above, it can be confirmed that the compound represented by Chemical Formula 1 according to the present invention is contained in the liquid raw material at 70 mol% or more (high yield achieved).

[0171]

[0172] Purification and concentration of liquid raw materials

[0173] [Example 2-1]

[0174] In the above Example 1-1, 0.1 g of activated carbon was added as an adsorbent to 100 g of the liquid raw material before recovering the excess unreacted alcohol and residual ethylene glycol (EG) using a fractional distillation device, and the liquid raw material was concentrated by filtering after stirring at 100°C for 3 hours.

[0175]

[0176] [Examples 2-2 to 2-16 and Comparative Examples 2-1 and 2-2]

[0177] The liquid raw material was purified and concentrated in the same manner as in Example 2-1, except that the conditions in Table 2 below were applied during the purification and concentration process of the liquid raw material. However, in Comparative Examples 2-1 and 2-2, the liquid raw materials of Comparative Examples 1-1 and 1-2 were precipitated in an undissolved state and were not purified.

[0178]

[0179] [Examples 2-17 to 2-19]

[0180] In Examples 1-1, 1-4 and 1-10, 100 g of the liquid raw material after recovering the excess unreacted alcohol and residual ethylene glycol (EG) using a fractional distillation device was purified by adding 0.1 g of activated carbon as an adsorbent, stirring at 100°C for 3 hours, and then filtering to concentrate the liquid raw material.

[0181]

[0182] [Comparative Examples 2-3 to 2-21]

[0183] In Examples 1-1 to 1-19, 100 g of the liquid raw material before recovering the excess unreacted alcohol and residual ethylene glycol (EG) using a fractional distillation device was stirred at 100°C for 3 hours without adding an adsorbent, and then filtered to concentrate the liquid raw material.

[0184]

[0185] [Test Example 2] Pigment Residue Rate

[0186] The liquid raw material 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 to 800 nm was obtained using a UV-vis spectrophotometer, and its area (A1) was measured. In addition, the absorbance curve of the liquid raw material of Comparative Example 2-3 (a composition in which the liquid raw material of Example 1-1 was used in the same manner as the composition of Example 2-1, but was concentrated without adding an adsorbent) was obtained using the same method as above, and its area (A2) was measured. The pigment residue rate (%) of the liquid raw material of Example 2-1 was calculated according to the following formula A using the area of ​​the measured absorbance curve, and the results are shown in Table 2 below.

[0187] [Formula A]

[0188]

[0189] The pigment residue rate (%) was calculated for Examples 2-2 to 2-26 and Comparative Examples 2-1 to 2-21 in the same manner as above.

[0190]

[0191] [Test Example 3] Yellowness

[0192] The liquid raw materials of Examples 2-1 to 2-26 and Comparative Examples 2-1 to 2-21 were diluted to a concentration of 5% each using dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), and methyl pyrrolidone (NMP), and then the yellowness index (YI) was measured using a ColorFlex EZ (manufacturer: HunterLab) device, and the results are shown in Table 2 below.

[0193]

[0194] Classification Composition Process Conditions Pigment Residual Rate (%) DMSO / DMF / NMPY.I DMSO / DMF / NMP Example 2-1 Example 1-1 Activated carbon 0.1g 100℃ / 3h 5.4 / 6.1 / 5.7 1.6 / 1.4 / 1.6 Example 2-2 Example 1-2 Activated carbon 0.1g 100℃ / 3h 6.8 / 6.5 / 6.0 1.4 / 1.5 / 1.3 Example 2-3 Example 1-3 Activated carbon 0.1g 100℃ / 3h 8.1 / 8.3 / 7.8 1.8 / 1.5 / 1.6 Example 2-4 Example 1-4 Activated carbon 0.1g 100℃ / 3h 7.8 / 8.0 / 7.9 1.7 / 1.7 / 1.3 Example 2-5 Example 1-5 Activated carbon 0.1g 100℃ / 3h 5.3 / 5.3 / 5.8 1.5 / 1.2 / 1.4 Example 2-6 Example 1-6 Activated carbon 0.1g 100℃ / 3h 6.5 / 5.5 / 6.1 1.1 / 1.3 / 1.6 Example 2-7 Example 1-7 Activated carbon 0.1g 100℃ / 3h 7.5 / 6.1 / 6.8 1.4 / 1.3 / 1.6 Example 2-8 Example 1-8 Activated carbon 0.1g 100℃ / 3h 6.0 / 5.3 / 6.1 1.3 / 1.4 / 1.3 Example 2-9 Example 1-8 Activated carbon 0.05g 100℃ / 3h 7.9 / 7.1 / 7.8 1.8 / 1.8 / 1.6 Example 2-10 Example 1-8 Activated carbon 0.5g 100℃ / 3h 5.1 / 4.8 / 4.0 0.9 / 1.0 / 0.8 Example 2-11 Example 1-8 Activated carbon 0.1g / silica gel 0.1g 100℃ / 3h 4.8 / 4.3 / 5 11.4 / 1.2 / 1.5 Example 2-12 Example 1-8 Activated carbon 0.05g / silica gel 0.05g 100℃ / 3h 7.0 / 7.3 / 6.9 1.6 / 1.3 / 1.2 Example 2-13 Example 1-9 Activated carbon 0.1g 100℃ / 3h 6.1 / 5.9 / 5.5 1.2 / 1.0 / 1.4 Example 2-14 Example 1-10 Activated carbon 0.1g100℃ / 3h8.1 / 7.9 / 7.50.9 / 1.1 / 1.4Example 2-15Example 1-11Activated carbon 0.1g100℃ / 3h7.4 / 6.9 / 6.11.0 / 1.3 / 1.6Example 2-16Example 1-12Activated carbon 0.1g100℃ / 3h6.6 / 6.0 / 6.21.2 / 1.5 / 1.7Example 2-17Example 1-1Activated carbon 0.1g100℃ / 3h5.1 / 5.0 / 4.91.5 / 1.5 / 1.6Example 2-18Example 1-3Activated carbon 0.1g100℃ / 3h8.4 / 8.2 / 7.81.7 / 1.6 / 1.6Example 2-19Example 1-7Activated carbon 0.1g100℃ / 3h7.7 / 7.1 / 7.81.5 / 1.4 / 1.6Comparative Example 2-1Comparative Example 1-1Activated carbon 0.1g100℃ / 3h1006.1 / 6.4 / 6.2Comparative Example 2-2Comparative Example 1-2Activated carbon 0.1g100℃ / 3h1007.2 / 7.3 / 7.0Comparative Example 2-3Example 1-1-100℃ / 3h1006.3 / 6.8 / 6.9Comparative Example 2-4Example 1-2-100℃ / 3h1006.6 / 6.9 / 7.0Comparative Example 2-5Example 1-3-100℃ / 3h1007.1 / 7.3 / 7.5Comparative Example 2-6Example 1-4-100℃ / 3h1007.3 / 7.2 / 7.4Comparative Example 2-7Example 1-5-100℃ / 3h1007.8 / 7.7 / 7.1Comparative Example 2-8Example 1-6-100℃ / 3h1008.0 / 8.3 / 8.3Comparative Example 2-9Example 1-7-100℃ / 3h1008.2 / 8.4 / 8.0Comparative Example 2-10Example 1-8-100℃ / 3h1007.1 / 7.3 / 7.5Comparative Example 2-11Example 1-9-100℃ / 3h1007.9 / 8.0 / 8.1 Comparative Example 2-12 Example 1-10-100℃ / 3h1008.3 / 8.3 / 8.6 Comparative Example 2-13 Example 1-11-100℃ / 3h1007.6 / 7.8 / 8.0 Comparative Example 2-14 Example 1-12-100℃ / 3h1007.2 / 7.3 / 7.6 Comparative Example 2-15 Example 1-13-100℃ / 3h1007.7 / 8.0 / 8.1 Comparative Example 2-16 Example 1-14-100℃ / 3h1007.9 / 7.8 / 8.2 Comparative Example 2-17 Example 1-15-100℃ / 3h1008.0 / 7.7 / 8.0Comparative Example 2-18Example 1-16-100℃ / 3h1007.6 / 8.0 / 7.3Comparative Example 2-19Example 1-17-100℃ / 3h1007.3 / 7.5 / 7.5Comparative Example 2-20Example 1-18-100℃ / 3h1007.7 / 7.6 / 8.0Comparative Example 2-21Example 1-19-100℃ / 3h1007.3 / 7.3 / 7.6.

[0195] Referring to Table 2 above, it can be confirmed that the liquid raw material according to the present invention has a lower pigment residue and improved yellowness as it goes through a purification and concentration process.

[0196]

[0197] <Manufacturing of polyester resin>

[0198] [Example 3-1]

[0199] (a) Preparation of preliminary composition

[0200] In a 10 L reactor connected to a column and a condenser that can be cooled by water, 51.5 mol of ethylene glycol (EG), 6.0 mol of cyclohexanedimethanol (CHDM), 2 mol of isosorbide (ISB), and 0.7 mol of diethylene glycol (DEG) were charged, and then the liquid raw material obtained in Example 2-1 was additionally charged in an amount such that the mole number of benzene rings in the liquid raw material became 50 mol. At this time, G / A (molar ratio of glycol component to diacid component) was 1.2.

[0201] 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 phenol-based oxidation stabilizer (product name: Iganox 1076, manufacturer: BASF) were added and stirred to prepare a preliminary composition.

[0202] (b) Esterification reaction

[0203] Nitrogen is injected into the reactor containing the above-mentioned preliminary composition to increase the pressure of the reactor by 1.0 kgf / cm compared to 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 260°C over 2 hours. Thereafter, the esterification reaction was performed at 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 inside the reactor was transferred to a 7 L reactor capable of vacuum reaction.

[0204] (c) polycondensation reaction

[0205] The pressure of the reactor containing the above product 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. The pressure of the reactor was maintained at 1.0 Torr (absolute pressure: 1.0 mmHg) or less to proceed with the polycondensation reaction. At this time, the stirring speed was set to be fast in the early stage of the polycondensation reaction, but as the polycondensation reaction progressed, if the stirring force weakened due to the increase in the viscosity of the mixture inside the reactor or the temperature of the mixture rose above the set temperature, the stirring speed was appropriately adjusted. The polycondensation reaction was proceeded 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 an average weight of about 12 to 14 mg.

[0206] (d) solid-state polymerization reaction

[0207] The above granulated product was allowed to stand at 150°C for 1 hour to crystallize, and then placed into a 20 L solid-state polymerization reactor. Thereafter, nitrogen was flowed into the solid-state polymerization reactor at a rate of 50 L / min. At this time, the temperature of the solid-state polymerization reactor was increased from room temperature to 140°C at a rate of 40°C / h and maintained at 140°C for 3 hours, then increased to 200°C at a rate of 40°C / h and maintained at 200°C. The solid-state polymerization reaction was performed until the intrinsic viscosity (IV) of the product (granulated product) in the reactor became 1.30 dl / g, thereby producing a polyester resin.

[0208]

[0209] [Examples 3-2 to 3-19 and Comparative Examples 3-1 and 3-21]

[0210] A polyester resin was manufactured in the same manner as in Example 3-1, except that the liquid raw materials were applied as shown in Table 3 below.

[0211]

[0212] [Example 4] Color characteristics

[0213] For the polyester resins of Examples 3-1 to 3-19 and Comparative Examples 3-1 to 3-21, 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.

[0214] Specifically, a 6 mm thick specimen was manufactured using 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 data was processed using a color analysis device within the Grams / 32 software to calculate Hunter Color L and Color b, and the Color Lb value, which is the difference between the Color L value and the Color b value, was calculated through this, and the results are shown in Table 3 below.

[0215]

[0216] Classification Composition Color Lb Example 3-1 Example 2-192 Example 3-2 Example 2-291 Example 3-3 Example 2-389 Example 3-4 Example 2-493 Example 3-5 Example 2-592 Example 3-6 Example 2-691 Example 3-7 Example 2-793 Example 3-8 Example 2-890 Example 3-9 Example 2-990 Example 3-10 Example 2-1089 Example 3-11 Example 2-1193 Example 3-12 Example 2-1291 Example 3-13 Example 2-1394 Example 3-14 Example 2-1489 Example 3-15 Example 2-1592 Example 3-16 Example 2-1691 Example 3-17 Example 2-1791 Example 3-18 Example 2-1893 Example 3-19 Example 2-1989 Comparative Example 3-1 Comparative Example 2-176 Comparative Example 3-2 Comparative Example 2-278 Comparative Example 3-3 Comparative Example 2-381 Comparative Example 3-4 Comparative Example 2-480 Comparative Example 3-5 Comparative Example 2-580 Comparative Example 3-6 Comparative Example 2-679 Comparative Example 3-7 Comparative Example 2-778 Comparative Example 3-8 Comparative Example 2-883 Comparative Example 2-9 Comparative Example 2-975 Comparative Example 3-10 Comparative Example 2-1076 Comparative Example 3-11 Comparative Example 2-1179 Comparative Example 3-12 Comparative Example 2-1280 Comparative Example 3-13 Comparative Example 2-1380 Comparative Example 3-14 Comparative Example 2-1482 Comparative Example 3-15 Comparative Example 2-1579 Comparative Example 3-16 Comparative Example 2-1681 Comparative Example 3-17 Comparative Example 2-1773 Comparative Example 3-18 Comparative Example 2-1881 Comparative Example 3-19 Comparative Example 2-1979 Comparative Example 3-20 Comparative Example 2-2079 Comparative Example 3-21 Comparative Example 2-2177

[0217] Referring to Table 3 above, it can be confirmed that the polyester resin according to the present invention (Examples 3-1 to 3-19) has a high Color Lb value and thus has excellent color characteristics.

Claims

1. (1) A step of obtaining a liquid raw material containing a compound represented by the following chemical formula 1 by alcoholyzing waste polyester with an alcohol having 4 or more carbon atoms; (2) a step of obtaining a product by subjecting a preliminary composition containing the above liquid raw material to an esterification reaction; and (3) A method for producing a polyester resin, comprising a step of subjecting the above product to a polycondensation reaction: [Chemical Formula 1] In the above chemical formula 1, R1 is alkyl having 4 or more carbon atoms.

2. In paragraph 1, A method for producing a polyester resin, which does not include a step of hydrolyzing the above liquid raw material.

3. In paragraph 1, A method for producing a polyester resin, wherein the liquid raw material contains 45 to 99.9 mol% of the compound represented by the chemical formula 1 based on the total molar number of the liquid raw material.

4. In paragraph 1, A method for producing a polyester resin, wherein the liquid raw material further comprises at least one selected from the group consisting of alcohol derivatives and oligomers.

5. In paragraph 4, A method for producing a polyester resin, wherein the liquid raw material comprises 0.01 to 50 mol% of the alcohol derivative and 0.01 to 50 mol% of the oligomer, based on the total molar number of the liquid raw material.

6. In paragraph 4, The above alcohol derivative comprises a compound represented by the following chemical formula 2, A method for producing a polyester resin, wherein the above oligomer comprises a compound represented by the following chemical formula 3: [Chemical Formula 2] [Chemical Formula 3] In the above chemical formulas 2 and 3, R2 and R3 are each independently alkyl having 4 or more carbon atoms, n is an integer greater than or equal to 1.

7. In paragraph 1, A method for producing a polyester resin, wherein the liquid raw material further comprises at least one selected from the group consisting of ethylene glycol and unreacted alcohol.

8. In paragraph 7, A method for producing a polyester resin, wherein the liquid raw material contains 0.01 to 50 mol% of the unreacted alcohol based on the total molar number of the liquid raw material.

9. In paragraph 1, A method for producing a polyester resin, wherein the above liquid raw material does not contain unreacted alcohol.

10. In paragraph 1, A method for producing a polyester resin, wherein the alcohol has 4 to 12 carbon atoms.

11. In paragraph 1, A method for producing a polyester resin, wherein the above alcoholysis is performed at a temperature of 160 to 280°C for 0.5 to 24 hours.

12. In paragraph 1, A method for producing a polyester resin, further comprising a step of adsorbing and purifying the liquid composition prior to the esterification reaction.

13. In paragraph 1, A method for producing a polyester resin, further comprising a step of fractionally distilling the liquid composition prior to the esterification reaction.

14. In paragraph 1, A method for producing a polyester resin, further comprising a step of concentrating the liquid composition prior to the esterification reaction.

15. In paragraph 1, A method for producing a polyester resin, wherein the preliminary composition comprises at least one selected from the group consisting of ethylene glycol, cyclohexanedimethanol, isosorbide, neopentyl glycol, 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, 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 and diethylene glycol.

16. In paragraph 1, A method for producing a polyester resin, wherein the waste polyester contains polyethylene terephthalate (PET) in an amount of 50 wt% or more based on the total weight of the waste polyester.

17. In paragraph 1, A method for producing a polyester resin, wherein the waste polyester comprises at least one selected from the group consisting of waste polyethylene terephthalate fibers, waste polyethylene terephthalate containers, waste polyethylene terephthalate films, and polyester waste (PIR).

18. A polyester resin manufactured by a manufacturing method according to any one of claims 1 to 17.

19. In paragraph 18, A polyester resin having a difference between the Color L value and the Color b value (Color Lb) measured using a spectrophotometer of 85 or more.

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