Polyester resin and polyester container manufactured therefrom

Abstract

The present invention relates to a polyester resin comprising a repeating unit derived from a polymerization raw material including regenerated bis (2-hydroxyethyl) terephthalate, a polyester preform prepared therefrom, and a polyester container manufactured therefrom. The polyester resin has a controlled content of acetaldehyde (AA), thereby preventing the leaching of acetaldehyde (AA) and providing a polyester container with excellent heat resistance, weather resistance, and color properties.

Description

Polyester resin and polyester container manufactured therefrom

[0001] The present invention relates to a polyester resin having excellent heat resistance and a controlled content of acetaldehyde (AA), and a polyester container manufactured from the polyester resin and having excellent heat resistance, weather resistance, color characteristics, etc.

[0002] Among polymer types, polyester resin is widely used as a material for beverage containers, various packaging films, and various interior and exterior materials because it has heat resistance, transparency, gas barrier properties, and high mechanical strength.

[0003] Various products manufactured using the aforementioned polyester resin are discarded as waste after use, causing serious environmental problems. Therefore, technologies for recycling polyester waste containing polyester resin are attracting attention.

[0004] Meanwhile, polyester resin is manufactured by introducing polymerization raw materials into a reactor and undergoing condensation polymerization, solid-state polymerization, etc. During the above reactions, acetaldehyde (AA), a side product, is generated, and this may remain in the polyester resin even after undergoing a separation and purification process.

[0005] When manufacturing a beverage container using a polyester resin containing the above-mentioned acetaldehyde (AA) residue, the flavor of the beverage contained in the beverage container may be altered, thereby reducing the drinkability of the beverage. Accordingly, a technology has been proposed to suppress the production of acetaldehyde (AA) by adding an additive such as an amine compound during the polymerization reaction of the polyester resin to minimize the residue of acetaldehyde (AA) in the polyester resin.

[0006] However, the use of the above additives creates new, undesirable by-products, making it difficult to secure the properties of the polyester resin, and there are also limitations in controlling the residual content of acetaldehyde (AA) to the required level.

[0007] Recently, in order to improve environmental problems that have become the biggest problem, a technology has been proposed as a method for recycling polyester waste, which involves chemically depolymerizing polyester waste to obtain a regenerated polymerization raw material and using it to manufacture polyester resin (regenerated polyester resin).

[0008] However, the inventors of the present invention have discovered that the recycled polymerization raw material obtained through the above depolymerization process has a high content of acetaldehyde (AA), which has a negative effect on the polyester resin manufactured using the raw material, as impurities that cause the production of acetaldehyde (AA) accumulate during the depolymerization process.

[0009] To solve this problem, the inventors of the present invention conducted various studies and found that by controlling the content of specific impurities (e.g., HA-ester, DEG-ester, BHET oligomer, etc.) contained in the regenerated polymerization raw material and using the same to manufacture a polyester resin, the content of acetaldehyde (AA) remaining in the polyester resin can be minimized.

[0010] Therefore, the task of the present invention is to provide a polyester resin that can exhibit required physical properties while improving environmental problems and minimizing the residual content of acetaldehyde (AA) without using a separate additive as in the prior art.

[0011] Another object of the present invention is to provide a polyester preform manufactured from the polyester resin.

[0012] Another object of the present invention is to provide a polyester container manufactured from the polyester resin and a method for manufacturing the same.

[0013] In order to solve the above problem, the present invention provides a polyester resin comprising a repeating unit derived from a polymerization raw material including recycled bis(2-hydroxyethyl)terephthalate, wherein when the polyester resin is molded at a temperature of 290°C and a preform obtained is analyzed by gas chromatography (GC), the polyester resin has an acetaldehyde (AA) content of 25 ppm or less.

[0014] In addition, the present invention provides a polyester preform manufactured from the polyester resin.

[0015] In addition, the present invention provides a polyester container manufactured from the polyester resin.

[0016] In addition, the present invention provides a method for manufacturing a polyester container, comprising the steps of: first molding the polyester resin at a temperature of 250 to 300°C to manufacture a polyester preform; and second molding the polyester preform.

[0017] The present invention manufactures a polyester resin using a recycled polymerization raw material that can minimize the generation of acetaldehyde (AA) during a polymerization reaction process of a polyester resin or a molding process of a polyester resin, thereby improving environmental issues and providing a polyester resin that has a very low acetaldehyde (AA) content and excellent heat resistance, heat stability, and color characteristics.

[0018] In addition, the present invention can provide a polyester container (e.g., a bottle containing a cold beverage or a hot beverage) that has excellent heat resistance, weather resistance, color characteristics, etc. and does not cause problems due to acetaldehyde (AA) by manufacturing a polyester container using the polyester resin.

[0019] 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.

[0020] 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.

[0021] In this specification, terms such as first, second, etc. are used to describe various components, and the components are not limited to these terms. These terms are used to distinguish one component from another.

[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] polyester resin

[0026] The polyester resin according to the present invention is a recycled polyester resin manufactured using a polymerization raw material including recycled bis(2-hydroxyethyl)terephthalate (r-BHET), and includes a repeating unit derived from the polymerization raw material, and when a preform obtained by molding the polyester resin at a temperature of 290°C is analyzed by gas chromatography (GC), the content of acetaldehyde (AA) is 25 ppm or less.

[0027] The above acetaldehyde (AA) is a substance that has a negative effect and can be generated during the polymerization reaction process of a polyester resin or the molding process of a polyester resin. The present invention controls the content of acetaldehyde (AA) contained in a preform obtained through the molding process of a polyester resin to a specific range of 25 ppm or less, thereby solving the above-described problem caused by acetaldehyde (AA).

[0028] For example, when a preform obtained by molding at the temperature of 290° C. is analyzed by gas chromatography (GC), the content of acetaldehyde (AA) contained in the preform may be less than 25 ppm, 24 ppm or less, less than 24 ppm, 23 ppm or less, 22 ppm or less, 21 ppm or less, 20 ppm or less, 19 ppm or less, 18 ppm or less, 17 ppm or less, 16 ppm or less, or 15 ppm or less (specifically, 0 to 25 ppm, more than 0 to less than 25 ppm, 0.01 to 24 ppm, 0.05 to 20 ppm, or 0.1 to 18 ppm).

[0029] Meanwhile, the polymerization raw material may be a regenerated polymerization raw material obtained through depolymerization of waste polyester. The depolymerization may be achieved through physical depolymerization or chemical depolymerization, and specifically, through a glycolysis reaction in which waste polyester is reacted with a glycol-based compound (e.g., ethylene glycol, diethylene glycol, etc.) to break the ester bonds of the waste polyester.

[0030] For example, the polymerization raw material may be obtained by first depolymerizing waste polyester and a glycol-based compound at 180 to 200°C (specifically, 180 to 195°C, 180 to 190°C, or 180 to 185°C) to obtain a reactant (first reactant), then secondly depolymerizing the obtained reactant (first reactant) and the glycol-based compound at 150 to 170°C (150 to 165°C, 150 to 160°C, or 150 to 155°C) to obtain a reactant (second reactant), and then separating and purifying the same.

[0031] The process for separating and purifying the above reactant (second reactant) is not particularly limited, but may include processes such as cooling and solid-liquid separation / ion exchange resin treatment / cooling crystallization / pressure filtering / distillation.

[0032] Specifically, the cooling and solid-liquid separation may be performed by cooling the reactant (second reactant) through a reduced pressure flash (@100 to 135° C. and 15 to 200 Torr) and then performing solid-liquid separation using a filter aid, whereby the reactant (second reactant) may be converted into a liquid reactant. By performing the cooling and solid-liquid separation, solid impurities such as fine particles and insoluble organic substances contained in the reactant (second reactant) may be removed, thereby increasing the yield and purity of the polymerization raw material.

[0033] The above ion exchange resin treatment may be performed by passing the liquid reactant through an ion exchange resin or by introducing an ion exchange resin into the liquid reactant. By performing this process, ionic impurities contained in the liquid reactant are removed, thereby obtaining a reactant (third reactant) with increased purity. The ion exchange resin used for the above ion exchange resin treatment may be a commonly known cation exchange resin, an anion exchange resin, an amphoteric ion exchange resin, a chelating resin, or a combination thereof.

[0034] The above cooling crystallization may be performed by cooling the reactant (third reactant) to form a crystal product. The temperature at which the reactant (third reactant) is cooled is not particularly limited, but may be specifically 70°C or lower, 60°C or lower, 50°C or lower, 40°C or lower, 30°C or lower, or 25°C or lower, and may be 0°C or higher, 5°C or higher, 10°C or higher, 15°C or higher, or 20°C or higher. By performing this cooling crystallization process, a crystal product from which impurities (e.g., acetate-based ester compounds, diethylene glycol ester compounds, etc.) are efficiently removed can be obtained.

[0035] The above pressure filtering may be performed by filtering the crystal product using a Nutsche filter or a filter press. The pressure and temperature for pressure filtering the crystal product are not particularly limited, but the pressure may be 0.1 to 21 bar, 0.5 to 10 bar, or 1 to 5 bar, and the temperature may be 5 to 35°C, 10 to 30°C, or 15 to 25°C. By performing this pressure filtering process, a reactant (fourth reactant) from which impurities (e.g., acetate-based ester compounds, diethylene glycol ester compounds, BHET dimer, BHET trimer, etc.) are efficiently removed may be obtained.

[0036] The above distillation can be performed by first subjecting the reactant (fourth reactant) to reduced pressure distillation and then secondarily subjecting it to thin-film distillation. By performing this distillation process, unreacted glycol compounds (e.g., ethylene glycol, diethylene glycol, etc.) are removed (recovered), and a result in which impurities (e.g., BHET dimer, BHET trimer, etc.) are efficiently removed can be obtained.

[0037] The result obtained through the above separation and purification process may undergo additional filtration and drying processes as needed, through which the polymerization raw material of the present invention can be obtained.

[0038] In the present invention, the reactant may mean a product obtained through each process.

[0039] The polymerization raw material obtained through the above process can exhibit high purity by minimizing impurities while having a high content of recycled bis(2-hydroxyethyl) terephthalate (hereinafter referred to as 'r-BHET').

[0040] Specifically, when the polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of bis(2-hydroxyethyl) terephthalate is 95% or more, which may mean that the polymerization raw material contains r-BHET and has high purity. For example, when the polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of bis(2-hydroxyethyl)terephthalate may be 95.3% or more, 95.5% or more, 95.8% or more, 96% or more, 96.2% or more, 96.5% or more, 96.7% or more, 97% or more, 97.2% or more, 97.5% or more, 97.8% or more, 98% or more, 98.2% or more, 98.5% or more, 99% or more, 99.5% or more, or 100% (specifically, 95 to 100%, 95.5 to 99.5%, 96 to 99%, or 97 to 98.5%). Since the polyester resin according to the present invention is manufactured using a polymerization raw material having high purity and including the above r-BHET, it can have excellent heat resistance, color characteristics, etc. while improving environmental issues.

[0041] According to the present invention, when the polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of the acetate ester compound (HA-ester) may be 1.0% or less. The acetate ester compound may include 2-hydroxyethyl (2-acetoxyethyl) terephthalate, which is a substance that causes the production of acetaldehyde (AA), which has a negative effect, so it is important to control its content.

[0042] Specifically, the acetate-based ester compound may be a by-product of acetate, which is introduced as a catalyst when depolymerizing waste polyester through a glycolysis reaction. That is, referring to the following reaction scheme 1, acetic acid derived from acetate used as a catalyst may react with ethylene glycol (EG) to produce an acetate-based compound such as 2-hydroxyethyl acetate (HA) and water (H2O). At this time, since the 2-hydroxyethyl acetate (HA) has a similar boiling point to ethylene glycol (EG), it is not easily filtered out as an impurity during the removal (recovery) process of ethylene glycol (EG), and as a result, as the process is repeated, side reactions are induced, which accumulates by-products such as acetate-based ester compounds. Specifically, referring to the following reaction scheme 2, an ester exchange reaction may occur between the 2-hydroxyethyl acetate (HA) and bis(2-hydroxyethyl)terephthalate (BHET), thereby producing an acetate ester compound such as 2-hydroxyethyl(2-acetoxyethyl)terephthalate (HAET) and ethylene glycol (EG).

[0043] [Reaction Formula 1]

[0044]

[0045] [Reaction Formula 2]

[0046]

[0047] Acetate ester compounds such as the above 2-hydroxyethyl(2-acetoxyethyl)terephthalate (HAET) are continuously accumulated during the depolymerization process, so that a polymerization raw material having a high residual content of acetate ester compounds is obtained. When a polyester resin or a polyester preform is manufactured using a polymerization raw material having a high residual content of acetate ester compounds, acetaldehyde (AA) may be generated by a side reaction of the acetate ester compound during the polymerization reaction or molding process, and thus a polyester resin or a polyester preform containing a relatively high content of acetaldehyde (AA) may be manufactured.

[0048] However, the present invention can provide a polyester resin and a polyester preform having a minimized content of acetaldehyde (AA) by using a polymerization raw material in which the content of an acetate-based ester compound (HA-ester), which is an impurity that causes the production of acetaldehyde (AA), is controlled to a specific range during the production of a polyester resin.

[0049] Specifically, when the polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of the acetate-based ester compound (HA-ester) may be 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.45% or less, 0.4% or less, 0.35% or less, 0.3% or less, 0.25% or less, or 0.24% or less (e.g., 0 to 1.0%, more than 0 to 0.5%, 0.01 to 0.4%, or 0.1 to 0.3%).

[0050] Meanwhile, according to the present invention, the polymerization raw material may have a peak area ratio of diethylene glycol ester compound of 2.0% or less in total when analyzed by high-performance liquid chromatography (HPLC). The diethylene glycol ester compound may be produced by an ester exchange reaction between diethylene glycol and bis(2-hydroxyethyl) terephthalate (BHET) during a process of depolymerizing waste polyester through a glycolysis reaction. These diethylene glycol ester compounds may specifically include 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate (DEG-ester-1) represented by the following chemical formula 1 and bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate (DEG-ester-2) represented by the following chemical formula 2.

[0051] [Chemical Formula 1]

[0052]

[0053] [Chemical Formula 2]

[0054]

[0055] Specifically, when the above polymerization raw material is analyzed by high performance liquid chromatography (HPLC), the peak area ratio of the diethylene glycol ester compound (DEG-ester) (e.g., peak area ratio of DEG-ester-1 + peak area ratio of DEG-ester-2) may be 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.95% or less, 0.9% or less, 0.7% or less, or 0.6% or less. For example, the peak area ratio of the diethylene glycol ester compound (DEG-ester) may be 0 to 2.0%, greater than 0 to 1.5%, greater than 0 to 1.0%, greater than 0 to 0.8%, greater than 0 to 0.7%, or 0.01 to 0.55%.

[0056] According to the present invention, when the polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of oligomers of dimers or higher may be 1.0% or less in total. The oligomers of dimers or higher may be specifically a dimer of bis(2-hydroxyethyl) terephthalate (BHET), a trimer of bis(2-hydroxyethyl) terephthalate (BHET), or a combination thereof. Such oligomers may have a molecular weight of 2,000 g / mol or less (e.g., 1,000 to 2,000 g / mol).

[0057] Specifically, when the polymerization raw material according to the present invention is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of oligomers of dimers or higher (e.g., peak area ratio of BHET dimer + peak area ratio of BHET trimer) may be less than 1.0% in total, 0.8% or less, 0.6% or less, 0.55% or less, 0.5% or less, 0.45% or less, 0.4% or less, 0.35% or less, or 0.3% or less. For example, the peak area ratio of oligomers of dimers or higher may be 0 to 1.0% in total, greater than 0 to 0.9%, greater than 0 to 0.7%, 0.01 to 0.5%, 0.05 to 0.45%, 0.1 to 0.4%, or 0.1 to 0.35%.

[0058] Meanwhile, as the content of diethylene glycol ester compound in the polymerization raw material increases, the melting point (T) indicating the degree of heat resistance of the polyester resin increases. m ) decreases linearly, and the acetate ester compound acts as a terminator that inhibits the growth of the polymer chain, so that as its content increases in the polymerization raw material, the heat resistance of the polyester resin decreases exponentially. Therefore, an equation for predicting the heat resistance of a polyester resin manufactured using a polymerization raw material (specifically, recycled bis(2-hydroxyethyl)terephthalate) can be derived based on this correlation.

[0059] Specifically, the polymerization raw material according to the present invention may have a thermal property drop index (TDI) of 6.0 or less, as expressed by Equation 1 below, when analyzed by high-performance liquid chromatography (HPLC).

[0060] [Formula 1] TDI = [DEG-ester-1] + ([DEG-ester-2]×2) + exp^[HA-ester]

[0061] In the above equation 1,

[0062] DEG-ester-1 is the peak area ratio (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl] terephthalate,

[0063] DEG-ester-2 is the peak area ratio (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate,

[0064] HA-ester is the peak area ratio (%) of 2-hydroxyethyl(2-acetoxyethyl) terephthalate,

[0065] Calculate by taking only the numerical values ​​of these parameters, excluding their units.

[0066] Specifically, when the thermal degradation index (TDI) represented by the above formula 1 is 6.0 or less, the heat resistance of the polyester resin can be more effectively prevented from being reduced by DEG-ester-1, DEG-ester-2, and HA-ester during the production of the polyester resin. For example, the thermal degradation index (TDI) may be 5.5 or less, 5.0 or less, 4.8 or less, 4.5 or less, 4.3 or less, or 4.0 or less (specifically, 0 to 5.5, 0.5 to 5.0, or 1.0 to 4.0).

[0067] According to the present invention, when the polymerization raw material is dissolved in dimethylformamide at a concentration of 25 wt% to prepare a solution (sample polymerization raw material solution), and the yellowness index (YID) of the prepared solution is measured, the yellowness index (YID) may be 5.0 or less. Specifically, the yellowness index (YID) may be 4.5 or less, 4.3 or less, 4.0 or less, 3.8 or less, 3.5 or less, 3.3 or less, 3.0 or less, 2.5 or less, 2.3 or less, 2.1 or less, 2.0 or less, 1.7 or less, 1.5 or less, or 1.3 or less. Since the polyester resin according to the present invention is prepared using the polymerization raw material with controlled yellowness (YID), it may have excellent color characteristics (e.g., transparency).

[0068] According to the present invention, the polyester resin has a glass transition temperature (T g ) and melting point (T m ) may have high heat resistance. For example, the glass transition temperature (T ) of the polyester resin measured by differential scanning calorimetry (DSC) g ) may be 80 ℃ or higher, and specifically 80.5 ℃ or higher, 81 ℃ or higher, 81.5 ℃ or higher, 82 ℃ or higher, or 82.5 ℃ or higher (e.g., 80 to 85 ℃, or 80.5 to 83 ℃). In addition, the melting point (T of the polyester resin measured by differential scanning calorimetry (DSC) m ) may be 240°C or higher, and specifically, 245°C or higher, 250°C or higher, 255°C or higher, 255.5°C or higher, 256°C or higher, 256.5°C or higher, 257°C or higher, or 257.5°C or higher (e.g., 255 to 260°C, or 257 to 258°C).

[0069] According to the present invention, the polyester resin may have a very low content of diethylene glycol (DEG), which is regarded as an impurity together with acetaldehyde (AA). Specifically, when the polyester resin is analyzed by gas chromatography (GC), the content of diethylene glycol (DEG) may be 2.0 wt% or less, and more specifically, 1.8 wt% or less, 1.5 wt% or less, 1.3 wt% or less, 1.0 wt% or less, 0.9 wt% or less, 0.8 wt% or less, 0.7 wt% or less, or 0.6 wt% or less (e.g., 0 to 2.0 wt%, more than 0 to 1.5 wt%, or 0.1 to 1.0 wt%).

[0070] These polyester resins may have excellent color characteristics (e.g., transparency). Specifically, when color L, a, and b are measured using CIE LAB indices, and the Lb value is calculated based on the measurement results, the Lb value may be greater than 80, 82 or more, 83 or more, 84 or more, 85 or more, 86 or more, 87 or more, 88 or more, or 89 or more (e.g., 81 to 90, or 85 to 89.5). The CIE LAB indices are color space coordinates defined by the CIE (Commission International d'Eclairage), and the L value represents brightness (0 to 100: 0 is black, 100 is white), the a value represents green-red (based on 0, + is red, - is green), and the b value represents yellow-blue (based on 0, + is yellow, - is blue).

[0071] In addition, the polyester resin may have excellent moldability by controlling the intrinsic viscosity (IV) within a specific range. Specifically, the polyester resin may have an intrinsic viscosity (solid intrinsic viscosity) (IV) of 0.75 to 0.85 dl / g, 0.76 to 0.84 dl / g, 0.77 to 0.83 dl / g, or 0.78 to 0.82 dl / g.

[0072]

[0073] polyester preforms

[0074] The polyester preform according to the present invention is manufactured from the polyester resin described above. For example, the polyester preform may be a polyester injection molded product obtained by injection molding the polyester resin described above. Since such a polyester preform is manufactured using the polyester resin described above, it has a very low acetaldehyde content and an intrinsic viscosity (IV) similar to that of the polyester resin, thereby exhibiting excellent thermal stability.

[0075] Specifically, when the polyester resin described above is molded at a temperature of 290°C to manufacture a polyester preform, and the polyester preform is analyzed by gas chromatography (GC), the content of acetaldehyde (AA) in the polyester preform may be 25 ppm or less. For example, the content of acetaldehyde (AA) of the polyester preform may be less than 25 ppm, 24 ppm or less, less than 24 ppm, 23 ppm or less, 22 ppm or less, 21 ppm or less, 20 ppm or less, 19 ppm or less, 18 ppm or less, 17 ppm or less, 16 ppm or less, or 15 ppm or less (specifically, 0 to 25 ppm, more than 0 to less than 25 ppm, 0.01 to 24 ppm, 0.05 to 20 ppm, or 0.1 to 18 ppm).

[0076] Additionally, the polyester preform may have an intrinsic viscosity (IV) of 0.75 to 0.82 dl / g, specifically 0.75 to 0.81 dl / g, 0.76 to 0.80 dl / g, or 0.76 to 0.79 dl / g.

[0077] According to the present invention, the polyester preform has an intrinsic viscosity change value (IV) according to the following equation 2 V ) may be 0.05 dl / g or less. Specifically, the intrinsic viscosity change value (IV V ) may be less than 0.05 dl / g, 0.04 dl / g or less, 0.03 dl / g or less, 0.02 dl / g or less, or 0.01 dl / g or less (e.g., 0.01 to 0.05 dl / g, 0.01 to 0.04 dl / g, or 0.01 to 0.03 dl / g). The intrinsic viscosity change value (IV V ) within the above range, thermal stability can be secured when manufacturing a polyester preform by molding a polyester resin.

[0078] [Formula 2] IV V = IV1- IV2

[0079] In the above equation 2,

[0080] IV1 is the intrinsic viscosity of the polyester resin,

[0081] IV2 is the intrinsic viscosity of the polyester preform (specifically, a preform obtained by molding a polyester resin at a temperature of 290°C).

[0082]

[0083] polyester container

[0084] The polyester container according to the present invention is manufactured from the polyester resin described above. Since this polyester container is manufactured using the polyester resin described above, it has excellent heat resistance, weather resistance, color characteristics (transparency), etc., and can minimize the release of acetaldehyde (AA) from the polyester container.

[0085] In particular, since the polyester container is manufactured using the polyester resin in which the content of acetaldehyde (AA) is controlled to a minimum, it can be suitably used as a beverage container for holding not only cold beverages but also hot beverages.

[0086] Meanwhile, according to the present invention, the polyester container has a color change value (C) according to the following formula 3 V ) may be 2 or less. Specifically, the color change value (C V ) may be less than 2, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, or 1.0 or less (e.g., 0 to less than 2, 0 to 1.9, or 0.5 to 1.5). The color change value (C V ) is within the above range, it is possible to prevent color change of the polyester container even when the polyester container is stored under high temperature and humid conditions.

[0087] [Formula 3] CV = C1- C2

[0088] In the above equation 3,

[0089] C1 is the difference (L1-b1) between the color L value (L1) and the color b value (b1) of the polyester container (initial polyester container),

[0090] C2 is the difference (L2-b2) between the color L value (L2) and the color b value (b2) of the polyester container obtained by leaving the polyester container (initial polyester container) in a constant temperature and humidity oven at 50°C and 60% relative humidity for 500 hours.

[0091]

[0092] Method for manufacturing polyester containers

[0093] The method for manufacturing a polyester container according to the present invention comprises the steps of: first molding the above-described polyester resin at a temperature of 250 to 300°C to manufacture a polyester preform; and second molding the polyester preform.

[0094] The temperature at which the polyester resin is first molded to manufacture the polyester preform may be specifically 260 to 295°C, 270 to 295°C, or 280 to 290°C.

[0095] The above primary molding may be performed by commonly known injection molding, extrusion molding, vacuum molding, etc., and preferably injection molding.

[0096] The above secondary molding is a molding process for completing the shape of the polyester container, and may preferably be blow molding. The blow molding process may be performed by a commonly known method.

[0097] 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.

[0098]

[0099] <Manufacturing of polymer raw materials>

[0100] [Preparation Example 1]

[0101] 1000 g of waste polyester resin, 2000 g of ethylene glycol, and 5.0 g of zinc acetate anhydride were charged into a first stainless steel (SUS) reactor, and the internal temperature of the first reactor was raised to 180°C to conduct a first depolymerization (first glycolysis reaction) for 2 hours to obtain a first reactant. The obtained first reactant was transferred to a second reactor and cooled to 150°C, and then 2000 g of ethylene glycol was additionally charged into the second reactor, and the internal temperature of the second reactor was maintained at 150°C to conduct a second depolymerization (second glycolysis reaction) for 2 hours to obtain a second reactant.

[0102] The obtained second reactant was cooled to 120 ℃ through a reduced pressure flash and then filtered through Celite TM 545) 16 g was added and pressure filtration was performed (solid-liquid separation) to obtain a liquid reactant. Next, the liquid reactant was passed through a column filled with an ion exchange resin (BC107(H) from Bonlite) to remove ionic impurities contained in the liquid reactant, thereby obtaining a third reactant containing bis(2-hydroxyethyl)terephthalate (BHET) and ethylene glycol.

[0103] The above third reactant was put into a 10 L jacket-type cooling water circulation crystallizer and cooled to room temperature over 2 hours while stirring at 100 rpm to crystallize. The crystal product obtained through the above crystallization was filtered through a pressurized Nutsche filter (jacket-type, filtration area 0.2 m 2 ) was used to separate solid and liquid under pressure conditions of 3 bar to obtain BHET cake as the fourth reactant.

[0104] The above BHET cake was transferred to a 10 L distillation apparatus, reheated to 130°C, and stepwise reduced pressure distillation was performed under reduced pressure conditions from 760 torr to 0.8 torr to remove (recover) unreacted ethylene glycol. The fifth reactant obtained by removing the above unreacted ethylene glycol was subjected to thin-film distillation under the conditions of 220°C and 0.08 Torr in a thin-film distiller (VKL70-4S from VTA) to obtain 1040 g of a product from which dimers or higher oligomers were removed.

[0105] Afterwards, 1040 g of the above-mentioned resultant and 3120 g of distilled water were placed in a 10 L glass reactor for adsorption-crystallization, dissolved at a temperature of 70°C, 5.2 g of activated carbon was added, stirred for 30 minutes, and filtered. Next, the filtrate was cooled to room temperature to crystallize, filtered again, and dried in a vacuum oven to obtain 1980 g of a polymerization raw material (polymerization raw material solution) containing regenerated bis(2-hydroxyethyl)terephthalate (r-BHET).

[0106]

[0107] [Preparation Example 2]

[0108] The procedure of Example 1 was repeated, but the time for the first glycolysis reaction was adjusted from 2 hours to 1 hour, thereby obtaining a polymerization raw material (polymerization raw material solution) containing regenerated bis(2-hydroxyethyl) terephthalate (r-BHET).

[0109]

[0110] [Preparation Example 3]

[0111] Repeat the procedure of Example 1, but use a filter press (filtration area 0.4 m) instead of a pressurized filter. 2 , 4 filter plates) was applied and filtered under a pressure condition of 18 bar to obtain a polymerization raw material (polymerization raw material solution) containing regenerated bis(2-hydroxyethyl) terephthalate (r-BHET).

[0112]

[0113] [Preparation Example 4]

[0114] The procedure of Example 1 was repeated, but waste polyester fibers were used instead of waste polyester resin, to obtain a polymerization raw material (polymerization raw material solution) containing recycled bis(2-hydroxyethyl) terephthalate (r-BHET).

[0115]

[0116] [Preparation Example 5]

[0117] The procedure of Example 1 was repeated, but the adsorption-crystallization process after the thin film distillation process was omitted, thereby obtaining a polymerization raw material (polymerization raw material solution) containing regenerated bis(2-hydroxyethyl) terephthalate (r-BHET).

[0118]

[0119] [Comparison Preparation Example 1]

[0120] The procedure of Example 1 was repeated, but the temperature of the first glycolysis reaction was controlled from 180°C to 210°C, and the temperature of the second glycolysis reaction was controlled from 150°C to 250°C, thereby obtaining a polymerization raw material (polymerization raw material solution) containing regenerated bis(2-hydroxyethyl)terephthalate (r-BHET).

[0121]

[0122] [Comparison Preparation Example 2]

[0123] The procedure of Example 1 was repeated, but the cooling crystallization process and the process using a pressurized Nutsche filter were omitted, thereby obtaining a polymerization raw material (polymerization raw material solution) containing regenerated bis(2-hydroxyethyl) terephthalate (r-BHET).

[0124]

[0125] [Example 1]

[0126] The following tests were conducted on the polymerization raw materials obtained above, and the results are shown in Table 1 below.

[0127]

[0128] (1) High-performance liquid chromatography (HPLC)

[0129] Approximately 0.01 g of the sample (polymerization raw material) was diluted in approximately 20 mL of methanol and analyzed by high-performance liquid chromatography (HPLC) (Model: Waters e2695; Column: C18 (4.6 × 250 mm), 5 μm; UV Detector: 242 nm; Injection volume: 10 μL; Eluent (Gradient) A: H2O+H3PO4, B: Acetonitrile). Afterwards, the peak area ratio (%) of the following components among the total peak area of ​​HPLC was calculated.

[0130] - MHET: Monohydroxyethyl terephthalate

[0131] - BHET: bis(2-hydroxyethyl) terephthalate

[0132] - DEG-ester-1: 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate

[0133] - DEG-ester-2: Bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate

[0134] - HA-ester: 2-hydroxyethyl (2-acetoxyethyl) terephthalate

[0135] - Dimer: BHET dimer

[0136] - Trimer: BHET trimer

[0137]

[0138] (2) Gas chromatography (GC)

[0139] 0.1 g of the sample (polymerization raw material) was dissolved in 10 mL CHCl3, processed through a 0.45 ㎛ filter, and analyzed by gas chromatography (GC).

[0140] - Model: Agilent 7890B

[0141] - Column: DB-624 (30 m×0.25 mm×1.4 ㎛)

[0142] - Oven Temp.: 60℃(2min)-10℃ / min-200℃(0 min)-20℃ / min-260℃(5 min)

[0143] - Injector Temp.: 250℃

[0144] - Detector Temp.: 250℃

[0145] - Flow: 1.5 mL / min (N2), Split ratio: 1 / 50

[0146]

[0147] (3) TDI

[0148] HPLC analysis was performed using the test method of (1) above, and the thermal property drop index (TDI) expressed by the following equation 1 was calculated.

[0149] [Formula 1] TDI = [DEG-ester-1] + ([DEG-ester-2]×2) + exp^[HA-ester]

[0150] In the above equation 1, DEG-ester-1 is the peak area ratio (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl]terephthalate, DEG-ester-2 is the peak area ratio (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, and HA-ester is the peak area ratio (%) of 2-hydroxyethyl(2-acetoxyethyl)terephthalate. When calculating equation 1, only the numerical values ​​excluding the units of these parameters are taken and calculated. Here, exp^ means an exponential function (e^).

[0151]

[0152] (4) Melting point (Tm)

[0153] The melting point was measured by increasing the temperature from 30 ℃ to 280 ℃ at a rate of 20 ℃ / min using a differential scanning calorimeter (DSC, TA instrument Q20).

[0154]

[0155] (5) Inductively coupled plasma atomic emission spectroscopy (ICP-AES)

[0156] After treating 0.3 g of the sample (polymerization raw material) with ultrasound and diluting it with ultrapure water, the content of inorganic substances (ppm) was measured using ICP-AES (Agilent Model 5100) (detection limit 5 ppm).

[0157]

[0158] (6) Yellowness Index (YID)

[0159] A solution was prepared by dissolving the sample (polymerization raw material) in dimethylformamide at a concentration of 25 wt% at room temperature, and the prepared solution was allowed to stand for 30 minutes, after which its yellowness was measured. Specifically, transmission data was obtained with Illuminant D65 using Hunterlab's Color Flex EZ at an observer angle of 2°, and the yellowness index (YID) value was calculated using the color analysis device within the software.

[0160]

[0161] 항목준비예 1준비예 2준비예 3준비예 4준비예 5비교준비예 1비교준비예 2HPLC(%)BHET98.2098.1098.5197.2296.2190.0491.20MHET0.781.100.671.701.721.8 22.14DEG-ester-10.410.320.220.440.805.201.85DEG-ester-20.040.020.020.080.12 1.320.98HA-ester0.200.210.110.230.410.331.12dimer0.210.200.340.280.220.220. 79trimer0.010.000.000.010.050.900.70기타0.150.050.130.040.470.171.22GC(wt%)잔류 EG0.100.100.100.100.200.220.23TDI1.711.591.381.862.559.236.87Tm(℃)112.2111.911 2.3112.5111.7109.2107.6ICP-AES(ppm)ZnN.DNDNDNDNDNDNDNDSbN.DNDNDNDNDNDNDNDNDFeN.DNDND NDNDNDNDPN.DNDNDND6N.DNDNDMnN.DNDNDNDNDNDNDNDNDMgN.DNDNDND5N.D.5AlN.DNDNDNDNDNDNDNDNDCoN.DNDNDNDNDNDNDNDNaN.DNDNDNDNDNDNDNDNDKN.DNDNDNDNDNDNDNDNDYID1.451.210.9

[0162] Referring to Table 1 above, it can be confirmed that the polymerization raw materials of Preparation Examples 1 to 5 according to the present invention have a total HPLC peak area ratio of diethylene glycol ester compounds (DEG-ester-1, DEG-ester-2) of 2.0% or less, a total HPLC peak area ratio of acetate-based ester compounds (HA-ester) of 1.0% or less, and the content of other impurities (MHET, dimer, trimer) and residual EG is very low. In addition, it can be confirmed that the results of melting point (Tm) and yellowness (YID) are also excellent.

[0163] In particular, since the polymerization raw materials of Preparation Examples 1 to 5 have a thermal degradation index (TDI) of 5.0 or less and a very low content of HA-ester, it can be expected that when using these to manufacture a polyester resin, a polyester resin having excellent heat resistance and a minimized content of acetaldehyde (AA) will be manufactured.

[0164]

[0165] <Manufacturing of polyester resin>

[0166] [Example 1]

[0167] In a 7 L reactor capable of vacuum reaction, 2775 g of the polymerization raw material (r-BHET-containing solution) of Preparation Example 1, 0.8 g of antimony oxide as a catalyst, 0.6 g of triethyl phosphate as a stabilizer, and 0.4 g of cobalt acetate as a coloring agent were charged. Subsequently, the temperature of the reactor was increased to 190 ° C. over 2 hours, and after reaching 190 ° C., the pressure of the reactor was decreased from normal pressure to 20 Torr over 30 minutes, and simultaneously, the temperature of the reactor was increased to 280 ° C. over 1 hour, and the polycondensation reaction was performed while maintaining the pressure of the reactor at 1 Torr or less. In the initial stage of the polycondensation reaction, the stirring speed was set to high, but as the reaction progressed, when the stirring force weakened due to the increase in the viscosity of the reactants or when the temperature of the reactants rose above the set temperature, the stirring speed was appropriately adjusted. The above polycondensation reaction was carried out until the intrinsic viscosity (IV) of the mixture (melt) within the reactor reached 0.64 dl / g. Thereafter, when the intrinsic viscosity (IV) of the mixture within the reactor reached the desired level, the mixture was discharged outside the reactor to be stranded, which was then solidified with a cooling liquid and granulated to an average weight of approximately 12 to 14 mg.

[0168] Next, the granulated obtained 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 / hr, maintained at 140°C for 3 hours, and then increased at a rate of 40°C / hr to 220°C, and the solid-state polymerization reaction was performed while maintaining 220°C. The solid-state polymerization reaction was performed until the intrinsic viscosity (IV) of the granulated obtained product became 0.81 dl / g, thereby obtaining a polyester resin (regenerated polyester resin).

[0169]

[0170] [Examples 2 to 5]

[0171] A polyester resin (regenerated polyester resin) was obtained by carrying out the same polymerization reaction process as in Example 1, except that the polymerization raw materials of Preparation Examples 2 to 5 were applied respectively.

[0172]

[0173] [Comparative Examples 1 and 2]

[0174] A polyester resin (regenerated polyester resin) was obtained by carrying out the same polymerization reaction process as in Example 1, except that the polymerization raw materials of Comparative Preparation Examples 1 and 2 were applied respectively.

[0175]

[0176] <Manufacturing of polyester containers>

[0177] [Manufacturing Examples 1 to 5]

[0178] The polyester resins obtained in Examples 1 to 5 were dried in a vacuum oven at 150°C and 1 torr or less for 10 hours, and then placed in a Nissei ASB 150 injection molding machine and subjected to primary injection molding under the conditions of a temperature of 290°C, a mold cooling time of 6 seconds, and a total cycle time of 20 seconds to manufacture a transparent preform weighing 50 g.

[0179] The manufactured preforms were formed using an LB01E bottle forming machine manufactured by Krupp at a primary pressure of 7 kg / cm 2 , secondary pressure 25 kg / cm 2 , after heating under the condition of an infrared lamp heater heating time of 26.5 seconds, a thermal equilibrium time of 8 seconds and a temperature of the preform immediately before bottle forming were set to 112 to 120°C, thereby producing a polyester bottle by bottle forming (secondary blow molding).

[0180]

[0181] [Comparative Manufacturing Examples 1 and 2]

[0182] A polyester bottle was manufactured by carrying out the same molding process as in Manufacturing Example 1, except that the polyester resins obtained in Comparative Examples 1 and 2 were applied, respectively.

[0183]

[0184] [Example 2]

[0185] The following tests were conducted on the polyester resin and polyester container obtained above, and the results are shown in Table 2 below.

[0186]

[0187] (1) Intrinsic viscosity (IV)

[0188] The sample (polyester resin or polyester preform) was dissolved in orthochlorophenol (OCP) at a concentration of 1.2 g / dL at 150°C to obtain a sample solution, and then the intrinsic viscosity was measured using an Ubbelohde viscosity tube. Specifically, the temperature of the viscosity tube was maintained at 35°C, and the time it took for the solvent to pass through a specific internal section of the viscosity tube (efflux time) and the time it took for the sample solution to pass through were measured to obtain the specific viscosity, which was then used to calculate the intrinsic viscosity.

[0189]

[0190] (2) Glass transition temperature (Tg) and melting point (Tm)

[0191] The glass transition temperature of the sample (polyester resin or polyester preform) was measured using a differential scanning calorimeter (DSC, Q20 model, TA instrument). Specifically, the sample was filled into an aluminum pan, heated from room temperature to 290 ℃ at 10 ℃ / min, maintained at 290 ℃ for 5 min, then cooled to 30 ℃ at -300 ℃ / min, and then heated to 280 ℃ at 10 ℃ / min. The glass transition temperature (T) was determined from the heat flow obtained. g ) and melting point (T m) was produced.

[0192]

[0193] (3) Gas chromatography (GC)

[0194] The sample (polyester resin or polyester preform) was analyzed by gas chromatography (GC, Agilent 7890B) to analyze the contents of residual DEG and acetaldehyde (AA). At this time, the polyester resin sample was applied by grinding the polyester resin into powder with a grinder, and aminolyzing 2 g of the powdered polyester resin with hydrazine hydrate. In addition, the polyester preform sample was applied by cutting the polyester preform, extracting 3.0 g, grinding it into powder with a freeze grinder, filtering it using a 30 Mesh filter, putting 1 g into a vial, sealing it, and heating and maintaining it at 150 ℃ for 40 minutes.

[0195]

[0196] (4) Polyester resin color (L - b)

[0197] The color L, a, and b of the sample (polyester resin) were calculated using a colorimeter (CHROMA METER CR-410, Konica Minolta) and the CIE LAB index was applied, and the Lb value was derived based on the results.

[0198]

[0199] (5) Polyester container color (L - b)

[0200] The chromaticity and brightness of polyester container specimens were measured using a Varian Cary 5 UV / Vis / NIR spectrophotometer equipped with a diffuse reflectance accessory. Specifically, the label panel part of the polyester container was cut to prepare a specimen measuring 30 mm in width × 30 mm in height, and transmittance data was obtained from this specimen using Illuminant D65 at an observer angle of 2°. The obtained transmittance data were processed using the color analysis device in the Grams / 32 software (CIE LAB index applied) to calculate color L, a, b, and the Lb value was derived based on the results. Furthermore, the color change value (C) according to the following Equation 3 was calculated. V ) was also produced.

[0201] [Formula 3] C V = C1- C2

[0202] In the above equation 3,

[0203] C1 is the difference (L1-b1) between the color L value (L1) and the color b value (b1) of the polyester container (initial polyester container specimen),

[0204] C2 is the difference (L2-b2) between the color L value (L2) and the color b value (b2) of the polyester container obtained by leaving the polyester container (initial polyester container specimen) in a constant temperature and humidity oven at 50°C and 60% relative humidity for 500 hours.

[0205]

[0206] Classification Manufacturing Example 1 (Example 1) Manufacturing Example 2 (Example 2) Manufacturing Example 3 (Example 3) Manufacturing Example 4 (Example 4) Manufacturing Example 5 (Example 5) Polyester Resin IV1 (dl / g) 0.8 1 0.7 9 0.8 2 0.7 7 0.7 8 Tg (℃) 8 2.2 8 2.0 8 2.5 8 1.5 8 0.8 Tm (℃) 257.4 257.6 257.9 257.2 256.2 DEG (wt%) 0.8 0.9 0.6 0.8 1.0 Color L - b88.487.889.387.286.6Polyester preform IV2(dl / g)0.780.770.790.760.76IV1-IV2(dl / g)0.030.020.030.010.02AA(ppm)1618151824Polyester container C1(Color L1-b1)94.594.694.894.593.9C2(Color L2-b2)(@50℃, 60%)93.193.493.89392C V (C1-C2)1.41.21.01.51.9

[0207] Comparison Manufacturing Example 1 (Comparative Example 1) Comparative Manufacturing Example 2 (Comparative Example 2) Polyester Resin IV1 (dl / g) 0.82 0.80 Tg (℃) 76.6 77.1 Tm (℃) 246.1 249.7 DEG (wt%) 6.5 2.8 Color L - b 74.5 80.0 Polyester Preform IV2 (dl / g) 0.70 0.72 IV1- IV2 (dl / g) 0.12 0.08 AA (ppm) 4235 Polyester Container C1 (Color L1-b1) 88.4 9 0.2 C2 (Color L2-b2) (@50℃, 60%) 84.4 87.7 C V (C1- C2)4.02.5

[0208] Referring to Tables 2 and 3 above, it can be confirmed that the polyester resins of Examples 1 to 5 according to the present invention have excellent heat resistance due to high glass transition temperature and melting point, and the content of residual diethylene glycol (DEG) and the by-product acetaldehyde (AA) is very low, making them suitable for manufacturing polyester containers (e.g., beverage bottles). In addition, it can be confirmed that there is almost no change in intrinsic viscosity (IV1-IV2) in the process of manufacturing a polyester preform from a polyester resin, so that the heat stability is excellent and the color characteristics are also secured.

[0209] Furthermore, it can be confirmed that the polyester containers of Manufacturing Examples 1 to 5 according to the present invention have excellent heat resistance and weather resistance, as there is little change in color characteristics even when placed under high temperature and high humidity conditions.

[0210] On the other hand, it can be confirmed that the polyester resins of Comparative Examples 1 and 2 have low glass transition temperatures and melting points, resulting in poor heat resistance, and high contents of residual diethylene glycol (DEG) and acetaldehyde (AA), a by-product, making them unsuitable for manufacturing polyester containers. This can be seen as a result of the polymerization raw materials of Comparative Preparation Examples 1 and 2, which have low purity, being applied in the manufacturing of the polyester resins of Comparative Examples 1 and 2, respectively.

Claims

1. A polyester resin comprising a repeating unit derived from a polymerization raw material containing recycled bis(2-hydroxyethyl)terephthalate, A polyester resin having an acetaldehyde (AA) content of 25 ppm or less when a preform obtained by molding the polyester resin at a temperature of 290°C is analyzed by gas chromatography (GC).

2. In paragraph 1, A polyester resin in which, when the above polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of bis(2-hydroxyethyl) terephthalate is 95% or more and the peak area ratio of acetate-based ester compound is 1.0% or less.

3. In paragraph 2, A polyester resin wherein the acetate ester compound comprises 2-hydroxyethyl (2-acetoxyethyl) terephthalate.

4. In paragraph 1, A polyester resin in which, when the above polymerization raw material is analyzed by high-performance liquid chromatography (HPLC), the peak area ratio of diethylene glycol ester compounds is 2.0% or less in total.

5. In paragraph 1, A polyester resin having a yellowness index (YID) of 5.0 or less of a solution obtained by dissolving the above polymerization raw material in dimethylformamide at a concentration of 25 wt%.

6. In paragraph 1, When the above polymerization raw material is analyzed by high performance liquid chromatography (HPLC), a polyester resin having a thermal property drop index (TDI) of 6.0 or less, as expressed by the following formula 1: [Formula 1] TDI = [DEG-ester-1] + ([DEG-ester-2]×2) + exp^[HA-ester] In the above equation 1, DEG-ester-1 is the peak area ratio (%) of 2-hydroxyethyl[2-(2-hydroxyethoxy)ethyl] terephthalate, DEG-ester-2 is the peak area ratio (%) of bis[2-(2-hydroxyethoxy)ethyl]benzene-1,4-dicarboxylate, HA-ester is the peak area ratio (%) of 2-hydroxyethyl(2-acetoxyethyl) terephthalate, Calculate by taking only the numerical values ​​of these parameters, excluding their units.

7. In paragraph 1, A polyester resin having a diethylene glycol (DEG) content of 2.0 wt% or less when the polyester resin is analyzed by gas chromatography (GC).

8. A polyester preform manufactured from a polyester resin according to any one of claims 1 to 7.

9. In paragraph 8, The intrinsic viscosity change value (IV) according to the following equation 2 V ) Polyester preform having a viscosity of 0.05 dl / g or less: [Formula 2] IV V = IV1- IV2 In the above equation 2, IV1 is the intrinsic viscosity of the polyester resin, IV2 is the intrinsic viscosity of the above polyester preform.

10. A polyester container manufactured from a polyester resin according to any one of claims 1 to 7.

11. In paragraph 10, Color change value (C) according to the following formula 3 V ) Polyester containers with a weight of 2 or less: [Formula 3] C V = C1- C2 In the above equation 3, C1 is the difference (L1-b1) between the color L value (L1) and the color b value (b1) of the polyester container, C2 is the difference (L2-b2) between the color L value (L2) and the color b value (b2) of the polyester container obtained by leaving the polyester container in a constant temperature and humidity oven at 50°C and 60% relative humidity for 500 hours.

12. A step of manufacturing a polyester preform by first molding the polyester resin according to any one of clauses 1 to 7 at a temperature of 250 to 300°C; and A method for manufacturing a polyester container, comprising a step of secondary molding the polyester preform.

13. In paragraph 12, A method for manufacturing a polyester container, wherein the first molding is injection molding and the second molding is blow molding.

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