Recycled polyester resin composition and molded article manufactured therefrom

Abstract

The present invention relates to a recycled polyester resin composition comprising recycled dimethyl terephthalate prepared using waste polyester, and a molded article manufactured therefrom. Specifically, according to an embodiment of the present invention, the recycled polyester resin composition includes: a recycled polyester resin including a repeating unit derived from a glycol component and a repeating unit derived from recycled dimethyl terephthalate (rDMT); a hindered phenol-based primary antioxidant; and a phosphorus-based or sulfur-based secondary antioxidant, thereby improving crystallinity, heat resistance, and volatility resistance. Therefore, when a molded article of a headlamp for a vehicle is manufactured using the recycled polyester resin composition, excellent performance can be exhibited.

Description

Regenerated polyester resin composition and molded article manufactured therefrom

[0001] The present invention relates to a recycled polyester resin composition comprising recycled dimethyl terephthalate manufactured using waste polyester, and a molded article manufactured therefrom.

[0002]

[0003] Polyester boasts excellent mechanical strength, heat resistance, transparency, and gas barrier properties, making it widely used in beverage containers, packaging films, audio and video films, and industrial materials such as medical fibers and tire cords. In particular, polyester sheets and boards, with their excellent transparency and mechanical strength, are widely used in cases, boxes, partitions, shelves, panels, packaging, building materials, and interior and exterior finishes.

[0004] Accordingly, plastic waste, such as polyester, is being generated globally at an unmanageable rate each year. Recently, countries around the world have been establishing regulations and measures for the recycling of waste plastic resources, including waste polyester. Physical and chemical methods are used to recycle waste polyester. Physical recycling methods are not widely used due to their inability to guarantee purity, while chemical recycling methods depolymerize waste polyester by breaking its ester bonds. These reactions include glycolysis, hydrolysis, methanolysis, and aminolysis.

[0005] Recently, research is going beyond simply recycling waste polyester, and is continuing to improve the quality of polyester products manufactured using recycled raw materials produced from recycled waste polyester. For example, there have been attempts to produce recycled polyester resins other than PET through glycolysis from waste polyethylene terephthalate (PET). However, this reaction involves excessive glycol usage and long reaction times, resulting in the generation of large amounts of byproducts. Furthermore, when PET is methanolyzed to produce recycled polyester resins other than PET, the properties of the final resin and the products made using it are significantly degraded, resulting in lower quality.

[0006] Meanwhile, examples of polyester products include automotive headlamps and headlight materials. Automotive headlamps include a reflector and a bezel housing the reflector to gather light from a light source and direct it forward. These bezels and reflectors are manufactured by depositing metal onto a substrate surface, and require complex designs and high gloss. Manufacturing such complexly designed molded parts requires high material fluidity. In other words, a material with high fluidity is essential to ensure high-quality molded parts without unformed parts even within complex mold structures. Recently, polybutylene terephthalate (PBT) resin has been used as a material that satisfies the high fluidity and smoothness required for molded parts such as automotive headlamps. Its rapid crystallization rate, short molding times, and excellent fluidity facilitate the creation of complex shapes. However, the increasing number of light sources and electrical components, such as the bezel and reflector in headlamps, has led to a diversification of heat sources, leading to increasingly complex designs. These diverse heat sources and the complex structure of headlamps can lead to temperature differences between the interior and exterior of the headlamp. This can lead to thermal decomposition of headlamp components, increasing the risk of haze. Consequently, the required properties of resins used as materials are gradually increasing.

[0007] Therefore, research is ongoing on recycled polyester resins and products manufactured using them, which have excellent quality and minimize the generation of byproducts by not using excessive alcohol or glycol in the process of recycling waste polyester, while not deteriorating the properties of the final resin manufactured using them and the products manufactured using them.

[0008] For example, Korean Patent Publication No. 2011-0080260 discloses a method for chemically regenerating polyester, which is easy to manufacture fine fiber yarn, functional yarn, etc., by depolymerizing waste polyester and ethylene glycol to produce an oligomer solution, contacting the oligomer solution with an ion exchange resin to remove a catalyst in the oligomer solution, then passing the oligomer solution from which the catalyst has been removed through a decolorizing agent to remove colored substances such as a coloring agent in the oligomer solution, and then performing condensation polymerization.

[0009] [Prior Art Literature]

[0010] (Patent Document 1) Korean Patent Publication No. 2011-0080260

[0011]

[0012] Accordingly, the present invention aims to provide a recycled polyester resin composition having excellent physical properties and a molded article manufactured therefrom, which can minimize the generation of by-products in a process of depolymerizing waste polyester and can produce high-purity recycled dimethyl terephthalate with excellent processability, and which includes the recycled dimethyl terephthalate.

[0013]

[0014] According to one embodiment of the present invention, a recycled polyester resin composition comprises a recycled polyester resin including a repeating unit derived from a glycol component and a repeating unit derived from recycled dimethyl terephthalate (rDMT); a hindered phenol-based primary antioxidant; and a phosphorus-based or sulfur-based secondary antioxidant, wherein the recycled polyester resin has a crystallized area value of 20% or more calculated according to the following Equation 1 for a crystallized region and an amorphous region obtained by separating crystal diffraction peaks appearing at 2θ values ​​of 0° to 50° during X-ray diffraction (XRD) analysis by an individual peak fitting method.

[0015] [Formula 1]

[0016]

[0017] According to another embodiment of the present invention, a molded article is manufactured from the above-described recycled polyester resin composition.

[0018]

[0019] A recycled polyester resin composition according to one embodiment of the present invention comprises a recycled polyester resin comprising repeating units derived from a glycol component and repeating units derived from recycled dimethyl terephthalate (rDMT); a hindered phenol-based primary antioxidant; and a phosphorus-based or sulfur-based secondary antioxidant, thereby improving crystallinity, heat resistance, and volatility resistance.

[0020] Typically, recycled dimethyl terephthalate (rDMT), manufactured from waste polyester, has low purity due to impurities arising from side reactions with reagents used in the depolymerization process. Attempts to improve purity through processes such as fractional distillation have been made, but these methods are inefficient and prohibit commercial application due to high process costs. Furthermore, there are limitations to improving purity.

[0021] A recycled polyester resin composition according to one embodiment of the present invention is manufactured by depolymerizing waste polyester and includes recycled dimethyl terephthalate having excellent color, purity, and crystallinity, thereby having excellent crystallinity, heat resistance, and volatility resistance.

[0022] Specifically, the recycled dimethyl terephthalate is manufactured by crystallizing a depolymerized composition manufactured by depolymerizing waste polyester at a low temperature, separating the slurry manufactured through the crystallization into solids and liquids, drying and washing, and then purifying it, thereby having excellent color, purity, and crystallinity. More specifically, the method for manufacturing the recycled dimethyl terephthalate has a low content of ethylene glycol byproducts that may be generated as side reactions in the process or terephthalate derivatives such as methyl hydrogen terephthalate (MHT) other than the desired DMT, so that color characteristics and purity can be improved, and quality can be improved when used as a raw material for various polymers. In addition, the method for manufacturing the recycled dimethyl terephthalate has excellent processability because it can manufacture high-purity recycled dimethyl terephthalate, and further, it is environmentally friendly because the content of ethylene glycol byproducts that may have an environmental impact is low.

[0023] Accordingly, the above-mentioned recycled polyester resin is manufactured using rDMT having excellent purity, crystallinity and color properties, and thus has excellent crystallinity as well as properties such as color, melting point (Tm), melting enthalpy and heat distortion temperature such as color-b and color-L, and therefore a product composed solely of the recycled polyester resin without mixing with commercially available polyester resins also has excellent quality.

[0024] Furthermore, by using the recycled polyester resin having the above-described excellent properties together with a hindered phenol-based primary antioxidant and a phosphorus or sulfur-based secondary antioxidant and controlling the content thereof, when manufacturing a vehicle headlamp molded product, more specifically a bezel or reflector, using the recycled polyester resin composition including such a configuration, excellent performance can be exhibited.

[0025]

[0026] Figure 1 shows the X-ray diffraction (XRD) analysis of resins A, D, E, H, and I.

[0027] Figures 2 to 6 show peaks separated by deconvolution of the X-ray diffraction peaks of resins D, A, E, H, and I using individual peak fitting, respectively.

[0028]

[0029] Hereinafter, the present invention will be described in detail. The present invention is not limited to the contents disclosed below and may be modified in various forms without changing the gist of the invention.

[0030] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0031] All numbers and expressions indicating the amounts of components, reaction conditions, etc. described in this specification should be understood to be modified by the term “about” in all cases unless otherwise specified.

[0032] In this specification, the terms "first," "second," etc. are used to describe various components, and the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0033] As used herein, a unit or group "derived from" a specific component refers to a portion of a final product resulting from a chemical reaction, such as a polymerization reaction, in which the component is modified or combined with other components during the reaction process. For example, a chain comprising a polymer may contain units or groups derived from one or more monomers.

[0034]

[0035] Regenerated polyester resin composition

[0036] According to one embodiment of the present invention, a recycled polyester resin composition comprises a recycled polyester resin comprising a repeating unit derived from a glycol component and a repeating unit derived from recycled dimethyl terephthalate (rDMT); a hindered phenol-based primary antioxidant; and a phosphorus-based or sulfur-based secondary antioxidant, wherein the recycled polyester resin has a crystallized area value of 20% or more calculated according to Equation 1 for a crystallized region and an amorphous region obtained by separating crystal diffraction peaks appearing at 2θ values ​​of 0° to 50° during X-ray diffraction (XRD) analysis by an individual peak fitting method.

[0037] The above-described recycled polyester resin composition may have a melt flow index (MI) of 60 g / 10 min or more as measured under the conditions of 250°C and 2.16 kg according to ASTM D1238. For example, the above-described recycled polyester resin composition may have a melt flow index of 60.5 g / 10 min or more, 61 g / 10 min or more, 62 g / 10 min or more, 65 g / 10 min or more, 70 g / 10 min or more, 72 g / 10 min or more, 76 g / 10 min or more, 80 g / 10 min or more, 85 g / 10 min or more, or 90 g / 10 min or more as measured under the conditions of 250°C and 2.16 kg according to ASTM D1238.

[0038] The above-mentioned recycled polyester resin composition may have a tensile strength of 45 MPa or more according to ASTM D638. For example, the above-mentioned recycled polyester resin composition may have a tensile strength of 46 MPa or more, 48 MPa or more, 49 MPa or more, 50 MPa or more, 52 MPa or more, 55 MPa or more, 57 MPa or more, or 58 or more according to ASTM D638.

[0039] The above-described recycled polyester resin composition may have a heat deflection temperature (HDT) of 175°C or higher, measured at a low load of 0.45 MPa according to ASTM D648. For example, the above-described recycled polyester resin composition may have a heat deflection temperature of 176°C or higher, 178°C or higher, 180°C or higher, 181°C or higher, 182°C or higher, 183°C or higher, 185°C or higher, 186°C or higher, or 188°C or higher, measured at a low load of 0.45 MPa according to ASTM D648.

[0040] The above-described recycled polyester resin composition may have a TVOC peak area of ​​80 area / g or less as measured by a gas chromatography / mass spectrometry (GC / MS) analysis method. For example, the above-described recycled polyester resin composition may have a TVOC peak area of ​​65 area / g or less, 60 area / g or less, 55 area / g or less, 50 area / g or less, 48 ​​area / g or less, 46 area / g or less, 44 area / g or less, 41 area / g or less, or 40 area / g or less as measured by a gas chromatography / mass spectrometry (GC / MS) analysis method.

[0041] In addition, the above-described regenerated polyester resin composition may have a haze change value of 5 or less according to the following formula 2.

[0042] [Formula 2]

[0043] Haze change value = |H1 - H2|

[0044] In equation 2,

[0045] H1 is the haze value measured before performing fogging evaluation under the conditions of 130℃ and 5 hours according to the DIN 75201-A test method for pellets manufactured using a recycled polyester resin composition, excluding the unit.

[0046] H2 is the unit-excluding haze value due to gas generated during fogging evaluation at 130°C for 5 hours according to DIN 75201-A test method for pellets manufactured using a recycled polyester resin composition.

[0047] For example, the above-described recycled polyester resin composition may have a haze change value according to the above-described formula 2 of 4.5 or less, 4 or less, 3.5 or less, 3 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.5 or less, or 2.2 or less.

[0048] In addition, for pellets manufactured using the above-described recycled polyester resin composition, the oxidation exotherm time measured by drying under reduced pressure at 50°C for 15 hours, increasing the temperature from 30°C to 240°C at 10°C / min using a differential scanning calorimeter (DSC, TA Instruments) in a nitrogen atmosphere, then changing the condition from nitrogen to air at a conversion rate of 20 ml / min, and maintaining 240°C for 60 minutes may be 10 minutes or more. For example, the oxidation exotherm time may be 10.5 minutes or more, 11 minutes or more, 12 minutes or more, 13 minutes or more, 15 minutes or more, 17 minutes or more, 17.5 minutes or more, 20 minutes or more, 25 minutes or more, 35 minutes or more, 50 minutes or more, or 60 minutes or more.

[0049] In addition, the above-described recycled polyester resin composition may have a melting point of 210°C or higher, and a melting enthalpy (△Hm) of 38 J / g or higher, as measured in a second scan using a differential scanning calorimeter. For example, the melting point may be 215°C or higher, 218°C or higher, 220°C or higher, 222°C or higher, or 225°C or higher, and may be 300°C or lower, 280°C or lower, 260°C or lower, or 240°C or lower, and the melting enthalpy may be 39.5 J / g or higher, 40 J / g or higher, 40.5 J / g or higher, 41 J / g or higher, 41.3 J / g or higher, 42 J / g or higher, 42.5 J / g or higher, 43 J / g or higher, 43.2 J / g or higher, or 43.5 J / g or higher.

[0050]

[0051] Regenerated polyester resin

[0052] A recycled polyester resin composition according to one embodiment of the present invention comprises a recycled polyester resin comprising a repeating unit derived from a glycol component and a repeating unit derived from recycled dimethyl terephthalate (rDMT).

[0053] The above-mentioned regenerated polyester resin may include repeating units derived from one or more glycol components and repeating units derived from one or more acid components.

[0054] The above-mentioned recycled polyester resin may be a homopolymer or a copolymer resin. As a specific example, the above-mentioned recycled polyester resin may be a polybutylene terephthalate (PBT) resin, which is a homopolymer resin comprising 1,4-butanediol as a constituent glycol component and recycled dimethyl terephthalate as an acid component. As another example, the above-mentioned recycled polyester resin may be a copolymer resin comprising 1,4-butanediol and an additional glycol as constituent glycol components, and recycled dimethyl terephthalate and an additional acid as acid components. The above-mentioned additional glycol and acid components may be additionally added in the esterification reaction step and / or the condensation polymerization reaction step, which will be described in detail in the method for producing a recycled polyester resin below.

[0055] According to one embodiment of the present invention, the regenerated polyester resin comprises a repeating unit derived from a glycol component.

[0056] The above glycol components are 1,3-propanediol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, copolymer of ethylene oxide and tetrahydrofuran, ethylene oxide addition polypropylene glycol, polycarbonate diol, polyneopentyl glycol, It may include at least one selected from the group consisting of poly-3-methylpentanediol and poly-1,5-pentanediol.

[0057] The above-mentioned recycled dimethyl terephthalate may be manufactured by depolymerizing waste polyester. Alternatively, the above-mentioned recycled dimethyl terephthalate may be manufactured by secondary depolymerizing recycled bis(2-hydroxyethyl) terephthalate (rBHET), which is manufactured by primary depolymerizing waste polyester. The method for manufacturing recycled dimethyl terephthalate will be described in detail below.

[0058] Conventionally, recycled terephthalate manufactured from waste polyester has poor physical properties such as color characteristics and low purity, making it difficult to use it alone as a raw material for polyester resin as an acid component. However, a recycled polyester resin according to an embodiment of the present invention is manufactured using the recycled terephthalate, and thus can secure sufficient physical properties even if the content of recycled terephthalate is increased compared to the conventional method, thereby having excellent quality. Therefore, a recycled polyester resin according to an embodiment of the present invention may contain the recycled terephthalate alone, or may contain it together with another acid component to improve physical properties, etc.

[0059] The above acid component may include at least one selected from the group consisting of adipic acid, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, fumaric acid, glutaric acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 4,4'-stilbenedicarboxylic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid.

[0060] The purity of the above-mentioned recycled dimethyl terephthalate may be 90% or higher. For example, the purity of the above-mentioned recycled dimethyl terephthalate may be measured by measuring the area of ​​a peak using high-performance liquid chromatography (UPLC) and then calculating the fraction (%) relative to the total peak area, and may be 91% or higher, 93% or higher, 95% or higher, 97% or higher, 98% or higher, 99% or higher, 99.5% or higher, or 99.9% or higher.

[0061] Specifically, 0.01 g of a sample is diluted in 20 mL of a mixture of methanol and 0.3% distilled aqueous phosphoric acid solution, and the area of ​​the peak is measured using high-performance liquid chromatography (UPLC), and the fraction (%) relative to the total peak area is calculated to determine the purity, components produced by side reactions, components produced other than the target DMT, and their contents. At this time, the dilution can be performed depending on the mobile phase and flow rate.

[0062] In addition, the recycled dimethyl terephthalate may have an APHA color value of 120 or less. For example, the recycled dimethyl terephthalate may be dissolved in a dimethylformamide solvent at a concentration of 10 wt% according to ASTM-D1209, placed in an analysis container with a quartz material and a light path length of 10 mm, and then measured in the transmittance mode of a colorimeter, and may be 105 or less, 100 or less, 93 or less, 90 or less, 85 or less, 65 or less, or 55 or less. APHA (American Public Health Association) is a colorimetric indicator that indicates the degree of contamination of a liquid, and a lower value indicates a closer color to pure water (colorless). Since the recycled dimethyl terephthalate has an APHA color value that satisfies the above range, it has high purity and a low degree of contamination by impurities, etc., and thus has excellent quality.

[0063] According to one embodiment of the present invention, the regenerated polyester resin has a crystallized area value of 20% or more calculated according to Equation 1 below for a crystallized region and an amorphous region obtained by separating crystal diffraction peaks appearing at 2θ values ​​of 0° to 50° during X-ray diffraction (XRD) analysis using an individual peak fitting method.

[0064] [Formula 1]

[0065]

[0066] Here, the crystallized area value (%) means the area of ​​the total area measured during X-ray diffraction (XRD) analysis of the polyester resin, i.e., the percentage (%) of the crystallized area area with respect to the sum of the areas of the crystallized area and the amorphous area. The area of ​​each area, which is the basis for calculating the crystallized area value (%) according to the present invention, is obtained by separating the peaks measured during X-ray diffraction (XRD) analysis of the polyester resin at 2θ values ​​of 0° to 50° using an individual peak fitting method, and can be calculated as an integral value for each crystallized area or amorphous area. Since the crystalline components are regularly arranged in a three-dimensional space, scattering caused by X-rays striking the diffraction surface occurs in a certain direction, and accordingly, the diffraction peak of the crystallized area appears as a high and narrow peak. However, since the amorphous components are irregularly arranged and scatter in various directions, the peak of the amorphous area is gently formed over a wide 2θ region (see FIGS. 2 to 6).

[0067] The larger the crystallized area value according to the above equation 1, and more specifically, the larger the ratio of each crystallized area separated by the individual peak fitting method, the better the crystallinity of the resin. In addition, the mechanical strength, heat resistance, chemical resistance, and other physical properties of the resin can also be improved. However, as the crystallinity increases, the adhesive strength decreases at temperatures lower than the melting point (Tm), which may limit the use of the resin. Therefore, it is important to control the physical properties within an appropriate range.

[0068] For example, for the above-mentioned recycled polyester resin, the crystallized area value calculated according to Equation 1 may be 20.5% or more, 21% or more, 21.5% or more, 22% or more, 22.5% or more, 23% or more, 25% or more, 26% or more, 27% or more, 29% or more, 30% or more, 31% or more, 33% or more, or 33.5% or more. Since the crystallized area value according to Equation 1 of the above-mentioned recycled polyester resin satisfies the above range, it has excellent crystallinity, and at the same time, it also has desirable properties such as mechanical properties, heat resistance, chemical resistance, and adhesive strength, so that it is easy to apply to various purposes.

[0069] The XRD analysis according to the above formula 1 may be a Wide Angle X-Ray Diffraction (WAXD) analysis, and may be performed by taking a picture of a WAXD plate using a SmartLab type X-ray diffraction device from Rigaku. When analyzing the WAXD, correction data that has been corrected for polarization factor, absorption factor, and air scattering may be used for the measurement data, and X-ray diffraction (XRD) analysis deconvolution and amorphous component region curve separation may be performed, and the crystallized area value (crystallized area value, %) calculated according to the above formula 1 may be calculated using the integral value for the crystallized region crystal diffraction peak and the amorphous region scattering intensity at 2θ values ​​of 0° to 50°.

[0070] Additionally, the above-mentioned regenerated polyester resin may have a difference in crystallized area value according to the following formula 3 that is negative.

[0071] [Formula 3]

[0072] Difference in crystallized area values ​​= Ca1- Ca2

[0073] In the above equation 3,

[0074] Ca1 is the unit-excluding value of the crystallized area calculated according to Equation 1 for a polyester resin containing repeating units derived from dimethyl terephthalate (virgin DMT),

[0075] Ca2 is the unit-deducted value of the crystallized area calculated according to Equation 1 for a recycled polyester resin containing repeating units derived from recycled dimethyl terephthalate (rDMT).

[0076] Specifically, the above Ca1 is a numerical value excluding the unit from the crystallized area value calculated according to the above formula 1 for a polyester resin containing repeating units derived from commercially available dimethyl terephthalate, not recycled dimethyl terephthalate manufactured from waste polyester. For example, the above Ca1 may be 20 or more, 20.5 or more, 21 or more, 21.5 or more, or 22 or more.

[0077] The above Ca2 is a numerical value excluding the unit from the crystallized area value calculated according to the above formula 1 for a recycled polyester resin containing repeating units derived from recycled dimethyl terephthalate manufactured from waste polyester. For example, the above Ca2 may be 20.5 or more, 21 or more, 21.5 or more, 22 or more, 22.5 or more, 23 or more, 25 or more, 25.5 or more, 27 or more, 29 or more, 30 or more, 31.5 or more, 32 or more, or 33.5 or more, as described above.

[0078] The difference in the crystallized area value according to the above formula 3 may be -0.5 or less, -1 or less, -2 or less, -3 or less, -4 or less, -5 or less, -6 or less, -7 or less, -8 or less, -9.5 or less, -10 or less, -11 or less, or -12 or less. Since the difference in the crystallized area value according to the above formula 3 satisfies the above range, it has superior crystallinity compared to a polyester resin containing commercially available dimethyl terephthalate rather than recycled dimethyl terephthalate.

[0079] In addition, the recycled polyester resin may have a total content (mol%) of ethylene glycol residues and diethylene glycol residues of 5 mol% or less based on the total mole number of the glycol component. Specifically, the recycled polyester resin may include ethylene glycol residues, and more specifically, may include ethylene glycol residues and diethylene glycol residues. For example, the recycled polyester resin may include 3.5 mol% or less, 2.5 mol% or less, 2 mol% or less, 1.8 mol% or less, or 1.5 mol% or less of ethylene glycol residues and diethylene glycol residues based on the total mole number of the glycol component, and may include 0.01 mol% or more, 0.02 mol% or more, 0.03 mol% or more, 0.05 mol% or more, or 0.1 mol% or more.

[0080] The above-mentioned recycled polyester resin may have an intrinsic viscosity at 35°C of 0.5 dL / g to 1.5 dL / g. For example, the above-mentioned recycled polyester resin may have an intrinsic viscosity at 35°C of 0.55 dL / g to 1.35 dL / g, 0.65 dL / g to 1.3 dL / g, 0.7 dL / g to 1.2 dL / g, 0.72 dL / g to 1.14 dL / g, 0.55 dL / g to 1.1 dL / g, or 0.6 dL / g to 0.7 dL / g.

[0081] The above-mentioned recycled polyester resin may have a color-b of 12 or less. For example, the color-b of the above-mentioned recycled polyester resin may be 10 or less, 9 or less, 8.5 or less, 8.1 or less, 7.5 or less, or 7 or less, and may be greater than 0, 1 or more, 2 or more, 2.5 or more, or 3 or more.

[0082] The above-mentioned recycled polyester resin may have a color-L of 70 or more. For example, the color-L of the above-mentioned recycled polyester resin may be 72 or more, 75 or more, 78 or more, 80 or more, 81 or more, 82 or more, or 83 or more.

[0083] The above color characteristics are a color system established by the International Standard Color Measurement Organization (CIE (Commission International d'Eclairage), and color is expressed by indicating color as L (brightness), a (complementary color from green to red), and b (complementary color from yellow to blue), and can be measured using a colorimeter.

[0084] In addition, the above-described recycled polyester resin may have a melting point of 210°C or higher, and a melting enthalpy (△Hm) of 38 J / g or higher, as measured in a second scan using a differential scanning calorimeter. For example, the melting point may be 215°C or higher, 218°C or higher, 220°C or higher, 222°C or higher, or 225°C or higher, and may be 300°C or lower, 280°C or lower, 260°C or lower, or 240°C or lower, and the melting enthalpy may be 39.5 J / g or higher, 40 J / g or higher, 40.5 J / g or higher, 41 J / g or higher, 41.3 J / g or higher, 42 J / g or higher, 42.5 J / g or higher, 43 J / g or higher, 43.2 J / g or higher, or 43.5 J / g or higher.

[0085] Specifically, the melting enthalpy can be measured by drying the recycled polyester resin under reduced pressure at 50°C for 15 hours, melting it at 260°C, rapidly cooling it to 30°C, and then scanning it at a heating rate of 10°C / min using a differential scanning calorimeter. At this time, the melting enthalpy can be measured using the 1st scan or the 2nd scan using the differential scanning calorimeter, and in the present specification, it is measured using the 2nd scan.

[0086] In the heat flow curve obtained by scanning, the first endothermic temperature is the glass transition temperature (Tg), the exothermic temperature measured after the glass transition temperature (Tg) is the crystallization temperature (Tc), and the endothermic temperature measured after the crystallization temperature (Tc) is the melting point (Tm). In addition, the integral at the melting point (Tm) was calculated as the melting enthalpy (△Hm).

[0087] Additionally, the recycled polyester resin may have a heat deflection temperature (HDT) of 90°C or higher, measured at a low load of 0.48 MPa according to ASTM D648. For example, the heat deflection temperature may be 92°C or higher, 94.5°C or higher, 95°C or higher, 96°C or higher, 98°C or higher, 98.4°C or higher, 99°C or higher, 99.3°C or higher, 99.5°C or higher, 100°C or higher, or 101°C or higher.

[0088]

[0089] Primary antioxidant

[0090] A recycled polyester resin composition according to one embodiment of the present invention includes a primary antioxidant.

[0091] The above primary antioxidant may be a phenolic antioxidant. The phenolic antioxidant can prevent oxidation of the recycled polyester resin composition while also thermally stabilizing the recycled polyester resin composition. The type of phenolic antioxidant is not particularly limited, and various commercially available phenolic antioxidants can be used. As a specific example, the recycled polyester resin composition according to one embodiment of the present invention includes a hindered phenolic primary antioxidant.

[0092] By way of example, the primary antioxidant may include tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy, alkyl ester (wherein the alkyl has 7 or 9 carbon atoms), triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, or a combination thereof.

[0093] The above-mentioned recycled polyester resin composition may contain 0.001 to 0.3 parts by weight of the primary antioxidant based on 100 parts by weight of the recycled polyester resin. For example, the content of the primary antioxidant may be 0.002 to 0.3 parts by weight, 0.005 to 0.3 parts by weight, 0.01 to 0.3 parts by weight, 0.01 to 0.25 parts by weight, 0.02 to 0.2 parts by weight, or 0.05 to 0.1 parts by weight based on 100 parts by weight of the recycled polyester resin.

[0094] By ensuring that the content of the primary antioxidant satisfies the above range, the recycled polyester resin composition and the molded article manufactured therefrom can advantageously secure an excellent appearance by minimizing discoloration or gas generation due to the decomposition of the recycled polyester resin composition by heat at high temperatures. If the content is less than the above range, an oxidation reaction may easily occur in a high-temperature environment, resulting in a deterioration of physical properties. If the content exceeds the above range, decomposition products such as the antioxidant may disperse to the surface in a high-temperature environment for a long period of time, resulting in poor fogging evaluation.

[0095] The heat stability effect of the above-mentioned antioxidant at high temperatures of polyester resin can be confirmed by the oxidative induction time (OIT). Many organic compounds, including polymers, tend to undergo oxidation reactions even at low temperatures in an oxygen-present environment. However, some substances have an induction period during which no reaction with oxygen occurs when exposed to isothermal conditions. This period is called the oxidation induction time (OIT), and the reaction rate with oxygen increases after this induction period. In other words, OIT represents information on the oxidative stability of a substance. Using DSC (Differential Scanning Calorimetry), the temperature is rapidly increased / stabilized to a desired temperature under a nitrogen atmosphere, then switched to an oxygen atmosphere and maintained in an isothermal state, and the time at which an exothermic reaction begins is designated as the OIT.

[0096]

[0097] secondary antioxidant

[0098] A recycled polyester resin composition according to one embodiment of the present invention comprises a secondary antioxidant. Specifically, the recycled polyester resin composition according to one embodiment of the present invention comprises a phosphorus-based or sulfur-based secondary antioxidant.

[0099] By way of example, the phosphorus antioxidant may include 3,9-bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol-di-phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol-di-phosphite, tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene diphosphonite, or a combination thereof.

[0100] In addition, the sulfur-based antioxidant may include, for example, dilauryl-3,3'-thiodipropionic acid ester, dimyristyl-3,3'-thiodipropionic acid ester, distearyl-3,3'-thiodipropionic acid ester, laurylstearyl-3,3'-thiodipropionic acid ester, pentaerythrityl tetrakis(3-laurylthiopropionic ester), or a combination thereof.

[0101] The above-mentioned recycled polyester resin composition may contain 0.001 to 0.2 parts by weight of the secondary antioxidant based on 100 parts by weight of the recycled polyester resin. For example, the content of the secondary antioxidant may be 0.002 to 0.2 parts by weight, 0.005 to 0.2 parts by weight, 0.01 to 0.2 parts by weight, or 0.02 to 0.18 parts by weight based on 100 parts by weight of the recycled polyester resin.

[0102] By ensuring that the content of the secondary antioxidant satisfies the above range, the recycled polyester resin composition and the molded article manufactured therefrom can advantageously secure an excellent appearance by minimizing discoloration or gas generation due to the decomposition of the recycled polyester resin composition by heat at high temperatures. If the content is less than the above range, an oxidation reaction may easily occur in a high-temperature environment, resulting in a deterioration of physical properties. If the content exceeds the above range, decomposition products such as the antioxidant may disperse to the surface in a high-temperature environment for a long period of time, resulting in poor fogging evaluation.

[0103]

[0104] Wax-based slip agent

[0105] A recycled polyester resin composition according to one embodiment of the present invention may include a wax-based slip agent.

[0106] By including a wax-based slip agent, it can be advantageous to secure release properties during injection molding of a molded product manufactured using the above-described recycled polyester resin composition.

[0107] The above wax may include at least one of a fatty acid ester-based lubricant and a montan-based lubricant.

[0108] The above fatty acid ester-based lubricant may include at least one selected from the group consisting of fatty acid esters of alcohols or polyhydric alcohols, hardened oils, butyl stearate, stearic acid monoglyceride, pentaerythritol tetrastearate, stearyl stearate, ester wax, and alkyl phosphate esters.

[0109] The above-mentioned montan wax may include at least one of a montan acid ester wax and a montan acid metal salt. The montan acid ester wax may have a saponification value of 20 mgKOH / g to 300 mgKOH / g or 50 mgKOH / g to 250 mgKOH / g. When the montan acid ester wax having the above-mentioned saponification value is included, the regenerated polyester resin composition and the molded article manufactured therefrom may have excellent mixing and releasability.

[0110] Specifically, the above-described recycled polyester resin composition may include a wax-based slip agent including at least one selected from the group consisting of fatty acid esters, fatty acid amides, polyethylene waxes, vegetable waxes, and mineral waxes.

[0111] The content of the wax-based slip agent may be 0.001 part by weight to 0.2 part by weight based on 100 parts by weight of the recycled polyester resin. For example, the content of the wax-based slip agent may be 0.002 part by weight to 0.2 part by weight, 0.005 part by weight to 0.2 part by weight, 0.01 part by weight to 0.18 part by weight, 0.02 part by weight to 0.15 part by weight, 0.05 part by weight to 0.15 part by weight, 0.05 part by weight to 0.12 part by weight, or 0.05 part by weight to 0.1 part by weight based on 100 parts by weight of the recycled polyester resin.

[0112] When the content of the wax-based slip agent satisfies the above range, the regenerated polyester resin composition and the molded article manufactured therefrom can exhibit excellent mixing and releasability. When the content exceeds the above range, the regenerated polyester resin composition and the molded article manufactured therefrom may have poor volatility resistance.

[0113]

[0114] In addition, the above-mentioned recycled polyester resin composition may include at least one additive selected from the group consisting of flame retardants, nucleating agents, coupling agents, fillers, plasticizers, impact modifiers, lubricants, antibacterial agents, release agents, inorganic additives, ultraviolet stabilizers, antistatic agents, pigments, and dyes.

[0115] The above-mentioned recycled polyester resin composition may contain the additive in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the above-mentioned recycled polyester resin. For example, the total content of the additive may be 0.02 to 2.5 parts by weight, 0.03 to 2 parts by weight, 0.05 to 1.5 parts by weight, 0.1 to 1.2 parts by weight, 0.2 to 1 part by weight, or 0.5 to 1 part by weight.

[0116]

[0117] molded products

[0118] According to another embodiment of the present invention, a molded article is manufactured from the above-described recycled polyester resin composition.

[0119] The above molded product is manufactured from the above recycled polyester resin composition and thus has excellent crystallinity, heat resistance, and volatility resistance.

[0120] The above molded product may be a molded product for a vehicle headlamp, but is not limited thereto.

[0121] As a specific example, the molded product may be in the form of pellets obtained by melt-extruding the recycled polyester resin composition using a twin-screw extruder at a temperature of 200°C to 300°C or 220°C to 260°C.

[0122]

[0123] Method for producing recycled dimethyl terephthalate

[0124] A method for producing recycled dimethyl terephthalate according to another embodiment of the present invention comprises the steps of depolymerizing waste polyester; and the step of crystallizing the produced depolymerized composition.

[0125] The waste polyester may be a pulverized or melted waste polyester product. For example, the waste polyester may be a pulverized polyester product that has been recovered and separated after use through consumption, or may be a pelletized product (PCR, post-consumer recycled material), or may be polyester waste (PIR, post-industrial recycled material), such as defective products or scraps that may be generated in processes such as forming polyester films, fibers, containers, etc., but is not limited thereto. As a specific example, the waste polyester may be waste polyethylene terephthalate (waste PET).

[0126] In addition, the waste polyester can be cut or crushed into sizes of 1 mm to 30 mm, 2 mm to 25 mm, or 3 mm to 20 mm to improve process efficiency in the depolymerization step, and can be washed and dried to be manufactured into recycled polyester chips and used.

[0127] For example, the waste polyester may have an intrinsic viscosity (IV) of greater than 0.3 dl / g, greater than 0.35 dl / g, greater than 0.4 dl / g, or greater than 0.45 dl / g, and less than or equal to 1.1 dl / g, less than or equal to 1.0 dl / g, or less than or equal to 0.9 dl / g.

[0128] A method for producing recycled dimethyl terephthalate according to another embodiment of the present invention comprises a step of depolymerizing waste polyester.

[0129] The above depolymerization may include alcoholysis. Specifically, the alcoholysis may be performed using alcohol, more specifically, monoalcohol or glycol. Additionally, the depolymerization may include glycolysis. Specifically, the glycolysis may be performed using ethylene glycol.

[0130] Additionally, the depolymerization may be performed at a temperature of 80°C to 240°C. For example, the depolymerization may be performed at a temperature of 85°C to 235°C, 90°C to 225°C, or 90°C to 220°C.

[0131] According to one embodiment of the present invention, the depolymerization may be performed in one step, or in two steps of primary depolymerization and secondary depolymerization.

[0132] As a specific example, the depolymerization may be performed by alcoholysis of waste polyester, and may be performed by first depolymerizing waste polyester to produce recycled bis(2-hydroxyethyl) terephthalate (rBHET), and then secondarily depolymerizing the rBHET. More specifically, the first depolymerization may be depolymerization through glycolysis using ethylene glycol, and the second depolymerization may be depolymerization through alcoholysis using alcohol.

[0133] For example, the waste polyester and methanol are introduced into the first high-pressure reactor, an alcoholysis catalyst is added, and alcoholysis can be performed while maintaining the seal by fastening all connecting parts of the first high-pressure reactor.

[0134] As another example, the waste polyester, ethylene glycol, and zinc acetate anhydride may be introduced into a stainless steel reactor and subjected to primary depolymerization through glycolysis to obtain solid rBHET. Thereafter, the solid rBHET and methanol may be introduced into a first high-pressure reactor, an alcoholysis catalyst may be added, and then all of the connecting parts of the first high-pressure reactor may be fastened to maintain a sealed state, and secondary depolymerization through alcoholysis may be performed to obtain solid rDMT.

[0135] The alcoholysis can be carried out at a temperature of 80°C to 240°C and a pressure of 2 bar to 60 bar for 2 to 5 hours. For example, the alcoholysis can be carried out at a temperature of 80°C to 235°C, 85°C to 230°C or 90°C to 230°C and a pressure of 2 bar to 60 bar, 3 bar to 60 bar, 4 bar to 60 bar, 3 bar to 20 bar, 3 bar to 15 bar, 35 bar to 60 bar, 40 bar to 60 bar or 50 bar to 60 bar for 2.5 to 5 hours, 2.5 to 4 hours or 3 to 5 hours.

[0136] An alcoholysis catalyst may be added during the above alcoholysis. The alcoholysis can be performed smoothly even as a non-catalytic reaction without the use of an alcoholysis catalyst, making it environmentally friendly. In particular, when the content of insoluble metals in waste polyester is high, a non-catalytic reaction may be advantageous for the efficient treatment and removal of impurities. Furthermore, an alcoholysis catalyst may be added from an energy perspective, which can enhance reactivity and thus processability.

[0137] The above alcohol decomposition catalyst may be a metal acetate salt, an alkali metal salt, or a hydroxy salt.

[0138] More specifically, the alcohol decomposition catalyst is Li+ , Na + , K + or Cs + Alkali metal ions, Be 2+ , Mg 2+ , Ca 2+ or Ba 2+ Alkaline earth metal ions, NH 4+ or NR 4+ Ammonium ion of (R is alkyl), and Zn 2+ One or more cations selected from the group consisting of; and OH - , OR - (R is alkyl), HCO3 - , CO3 2- , benzoate ion (C7H5O2 - ), may include at least one anion selected from the group consisting of 4-alkoxycarbonylbenzoate ion, acetate ion, and terephthalate ion. The R may be an alkyl having 1 to 10 carbon atoms or an alkyl having 1 to 5 carbon atoms.

[0139] For example, the above alcoholysis catalyst is Zn(OAC)2, Co(OAc)2, Mn(OAc)2, Mg(OAc)2, Ca(OAc)2, Ba(OAc)2, LiOAc, NaOAc, KOAc, Zn(OAC)2·2H2O, Co(OAc)2·4H2O, Pb(OAc)2, Mn(OAc)2·4H2O, Mg(OAc)2·4H2O, Pd(OAc)2, It may include at least one selected from the group consisting of Ti(OBu)4, Ti(OiPr)4, GeO2, Al(OiPr)3, Na2CO3, K2CO3, dibutyltin(IV) oxide, tin octoate, titanium phosphate, and terephthalic acid.

[0140] The amount of the alcoholysis catalyst to be added may be 10 ppm to 10,000 ppm relative to the total weight of the waste polyester. For example, when the first stage of depolymerization is performed, the amount of the alcoholysis catalyst to be added may be 10 ppm to 9,000 ppm, 50 ppm to 8,000 ppm, 100 ppm to 6,000 ppm, 250 ppm to 3,500 ppm, 300 ppm to 2,000 ppm, 500 ppm to 1,500 ppm, or 600 ppm to 1,200 ppm relative to the total weight of the waste polyester.

[0141] In addition, the amount of the alcoholysis catalyst may be 10 ppm to 10,000 ppm based on the total weight of the rBHET. For example, when two-stage depolymerization is performed and the depolymerization for the alcoholysis reaction is a secondary depolymerization, the amount of the alcoholysis catalyst based on the intermediate product manufactured through the first depolymerization, specifically, the total weight of the rBHET, may be 10 ppm to 9,000 ppm, 50 ppm to 8,000 ppm, 100 ppm to 6,000 ppm, 250 ppm to 3,500 ppm, 300 ppm to 2,000 ppm, or 300 ppm to 1,500 ppm.

[0142] Additionally, the glycolysis may be performed at 160°C to 240°C. For example, the glycolysis may be performed by raising the temperature inside the reactor to 170°C to 220°C, 175°C to 210°C, or 185°C to 200°C.

[0143] A method for producing regenerated dimethyl terephthalate according to another embodiment of the present invention includes a step of crystallizing the produced depolymerization composition.

[0144] The crystallization step may be performed by cooling the depolymerization composition to 25°C to 60°C and stirring at a low speed of 10 rpm to 30 rpm for 1 to 6 hours or leaving it alone. For example, the crystallization step may be performed by stirring the depolymerization composition at a low speed of 10 rpm to 25 rpm or 10 rpm to 20 rpm for 1 to 5 hours or 2 to 4 hours at a temperature of 25°C to 55°C, 30°C to 60°C, or 40°C to 55°C.

[0145] More specifically, by performing a crystallization step according to the above conditions after depolymerization is completed, a depolymerized composition in the form of a slurry can be obtained. As a specific example, by performing a crystallization step according to the above conditions after depolymerization is completed through alcoholysis, a slurry-form depolymerized composition can be obtained. The slurry-form depolymerized composition may include solid-phase recycled dimethyl terephthalate (rDMT), an excess of unreacted methanol, a small amount of liquid-phase dissolved recycled dimethyl terephthalate (rDMT), ethylene glycol derivatives, polyester oligomers, methanol-terminated oligomers, etc. produced as side reactions.

[0146] At this time, the depolymerization composition obtained through the crystallization step may include ethylene glycol derivatives produced as a side reaction or terephthalic acid and terephthalate derivatives produced in addition to the desired DMT or BHET, and the components and contents of each of these can be analyzed using high-performance liquid chromatography (UPLC).

[0147] Additionally, after the depolymerization is completed, the components introduced for depolymerization can be recovered through layer separation or fractional distillation. As a specific example, methanol introduced for alcoholysis or ethylene glycol introduced for glycolysis can be recovered through layer separation or fractional distillation.

[0148] Additionally, in the above depolymerization step, an ethylene glycol derivative as a by-product may be produced.

[0149] The content of the ethylene glycol derivative may be 5 wt% or less relative to the total weight of the recycled dimethyl terephthalate. For example, the ethylene glycol derivative may include ethylene glycol and diethylene glycol, and the content of the ethylene glycol derivative relative to the total weight of the recycled dimethyl terephthalate may be 4 wt% or less, 3.5 wt% or less, 3 wt% or less, 2.5 wt% or less, or 2 wt% or less, and may be 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, or 0.5 wt% or more.

[0150] Additionally, in the above depolymerization step, by-products such as terephthalic acid and terephthalate derivatives can be produced.

[0151] The above terephthalate derivatives do not include dimethyl terephthalate, but include dimethyl isophthalate (DMI), methyl hydrogen terephthalate (MHT), 1-(2-hydroxyethyl)-4-methyl terephthalate (HEMT), ethylmethyl terephthalate (EMT), mono(hydroxylethyl) terephthalate (MHET), 2-hydroxyethyl [2-(2-hydroxyethoxy)ethyl] terephthalate (HEHDET), and bis[2-(2-hydroxyethoxy)ethyl] terephthalate (Bis[2-(2-hydroxyethoxy)ethyl] terephthalate; It may be at least one selected from the group consisting of, but is not limited to, BDHET.

[0152] At this time, the content of the terephthalic acid and terephthalate derivatives may be 10 wt% or less relative to the total weight of the regenerated dimethyl terephthalate. For example, the content of the terephthalic acid and terephthalate derivatives may be 9 wt% or less, 8 wt% or less, 6.5 wt% or less, 5 wt% or less, 3 wt% or less, 1.5 wt% or less, or 1 wt% or less relative to the total weight of the regenerated dimethyl terephthalate.

[0153] In addition, the rDMT finally manufactured through the depolymerization may include an inorganic compound. For example, the rDMT finally manufactured may include one or more inorganic compounds selected from the group consisting of antimony-containing compounds, germanium-containing compounds, titanium-containing compounds, zinc-containing compounds, cobalt-containing compounds, tin-containing compounds, aluminum-containing compounds, magnesium, sodium salts, potassium salts, phosphorus-containing compounds, and sulfur-containing compounds. The inorganic compound may be derived from waste polyester, and may be an additional component added during the depolymerization process. The content of the inorganic compound may be 10 ppm to 500 ppm, 30 ppm to 400 ppm, 50 ppm to 350 ppm, or 100 ppm to 300 ppm based on the total weight of the rDMT.

[0154] According to one embodiment of the present invention, the method for producing the regenerated dimethyl terephthalate may additionally include at least one step selected from the group consisting of a solid-liquid separation step, a drying step, a washing step, and a purification step.

[0155] For example, after the crystallization step, a washing step and a purification step may be performed, and after the crystallization step, a solid-liquid separation step, a washing step and a purification step may be performed.

[0156] More specifically, after the crystallization step, the solid-liquid separation step, the drying step, the washing step, and the purification step may be sequentially performed. As a specific example, the depolymerized composition obtained through the crystallization step may be subjected to solid-liquid separation, followed by drying and washing to obtain rDMT in the form of a wet cake. The washed rDMT in the form of a wet cake may be purified to obtain rDMT in a solid phase.

[0157] The solid-liquid separation can be performed using a centrifuge. Specifically, the solid-liquid separation can separate the solid rDMT or rBHET contained in the depolymerization composition from the liquid components introduced in the depolymerization, such as ethylene glycol and methanol. Specifically, the solid-liquid separation can be performed using a centrifuge at 1,000 rpm to 4,000 rpm, 1,500 rpm to 3,500 rpm, or 2,000 rpm to 3,000 rpm.

[0158] The drying step may be performed at a temperature of 85°C to 130°C. For example, the temperature at which the drying step is performed may be 90°C to 120°C, 95°C to 110°C, or 95°C to 105°C.

[0159] The washing may be performed three or more times using a mixture of alcohol and / or water, a protic solvent such as isopropanol or acetic acid, or an aprotic solvent such as acetone, dichloromethane, chloroform, tetrahydrofuran (THF), or toluene. The washing effectively removes residual pigments or yellow impurities generated by pigment decomposition during hydrolysis, thereby improving color characteristics.

[0160] The purification step may be performed by fractional distillation at a temperature of 170°C to 240°C and a reduced pressure of 100 torr or less. For example, the purification step may be performed by fractional distillation at a temperature of 175°C to 235°C, 180°C to 225°C, or 190°C to 220°C and a reduced pressure of 100 torr or less, 80 torr or less, or 60 torr or less. In addition, the purification step may additionally include a step of cooling to room temperature after the fractional distillation.

[0161]

[0162] Method for producing recycled polyester resin

[0163] According to another embodiment of the present invention, a method for producing a recycled polyester resin comprises the steps of: depolymerizing waste polyester to produce recycled dimethyl terephthalate (rDMT); mixing the rDMT with a glycol component and subjecting it to an esterification reaction to produce recycled bis(4-hydroxybutyl) terephthalate (rBHBT); and subjecting the rBHBT to a condensation polymerization reaction to produce a recycled polyester resin, wherein the recycled polyester resin has a crystallized area value of 20% or more calculated according to Equation 1 for a crystallized region and an amorphous region obtained by separating crystal diffraction peaks appearing at 2θ values ​​of 0° to 50° during X-ray diffraction (XRD) analysis by an individual peak fitting method.

[0164] The step of depolymerizing the above waste polyester to produce recycled dimethyl terephthalate is as described above.

[0165] The description of the above glycol component is as described above, and the rDMT forms a residue of bis(4-hydroxybutyl)terephthalate (rBHBT) or an oligomer thereof through an esterification reaction with glycol. More specifically, the rBHBT and its oligomers can form a polymer chain of the polyester resin to be finally manufactured.

[0166] The above esterification reaction may be performed at 165°C or higher, 170°C or higher, 180°C or higher, or 190°C or higher, and may be performed at 225°C or lower, 220°C or lower, 215°C or lower, 210°C or lower, or 205°C or lower. For example, the esterification reaction may be performed at a temperature of 170°C or higher to facilitate smooth removal of methanol, which is a by-product, and may be performed at a temperature 10°C lower than the boiling point of the glycol to be substituted to reduce loss of the glycol. As a specific example, the esterification reaction of 1,4-butanediol and rDMT may be performed at 170°C to 220°C.

[0167] In addition, the above esterification reaction is at 0 kg / cm compared to atmospheric pressure. 2 10 kg / cm 2 (0 mmHg to 7355.6 mmHg), 0 kg / cm 2 5 kg / cm 2 (0 to 3677.8 mmHg) or 0 kg / cm 2 2.0 kg / cm 2 (0 to 1471.1 mmHg). In addition, the esterification reaction can be performed for 1 hour to 24 hours, 1 hour to 10 hours, or 1 hour to 6 hours.

[0168] The polycondensation reaction may be performed at a temperature of 150°C to 300°C, 200°C to 290°C, 240°C to 280°C, or 260°C to 280°C. In addition, the polycondensation reaction may be performed under reduced pressure conditions of 0.01 mmHg to 600 mmHg, 0.05 mmHg to 300 mmHg, or 0.1 mmHg to 100 mmHg. In addition, the polycondensation reaction may be performed for a necessary time until a desired intrinsic viscosity is reached, and may be performed for, for example, 1 hour to 24 hours, 1 hour to 10 hours, or 1 hour to 4 hours. When the process conditions of the polycondensation reaction satisfy the above range, it may be advantageous to remove glycol, which is a byproduct of the polycondensation reaction, from the system.

[0169] At the beginning of the polycondensation reaction, the stirring speed is set to high, and as the polycondensation reaction progresses, the stirring force becomes weak due to the increase in the viscosity of the reactants, or the temperature of the reactants rises above the set temperature, the stirring speed can be appropriately adjusted accordingly.

[0170] Additionally, a glycol component or an acid component may be additionally added in the esterification reaction step and / or the condensation polymerization reaction step.

[0171] The above glycol components are 1,3-propanediol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, copolymer of ethylene oxide and tetrahydrofuran, ethylene oxide addition polypropylene glycol, polycarbonate diol, polyneopentyl glycol, It may include at least one selected from the group consisting of poly-3-methylpentanediol and poly-1,5-pentanediol.

[0172] The above acid component may include at least one selected from the group consisting of adipic acid, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, fumaric acid, glutaric acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 4,4'-stilbenedicarboxylic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid.

[0173] Additionally, a catalyst and / or stabilizer may be additionally added in the esterification reaction and the condensation polymerization reaction.

[0174] For example, the esterification reaction catalyst may be a methylate of sodium or magnesium; an acetate, borate, fatty acid salt, or carbonate of Zn, Cd, Mn, Co, Ca, or Ba; a metal Mg; an oxide of Pb, Zn, Sb, Ge, or Ti; or the like.

[0175] In addition, the polycondensation reaction catalyst may be, for example, a titanium-based catalyst such as tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, lactate titanate, triethanolamine titanate, acetyl acetonate titanate, ethyl acetoacetic ester titanate, isostearyl titanate, titanium dioxide, titanium dioxide / silicon dioxide copolymer, titanium dioxide / zirconium dioxide copolymer, etc.; a germanium-based catalyst such as germanium dioxide and copolymers using the same; or a tin-based catalyst such as monobutyl tin oxide, dibutyl tin oxide, monobutyl hydroxy tin oxide, etc.

[0176] Additionally, the stabilizer may be a phosphorus compound such as phosphoric acid, trimethyl phosphate, or triethyl phosphate, but is not limited thereto.

[0177] A method for producing a polyester resin according to another embodiment of the present invention may further include a step of conducting a solid-state polymerization reaction. For example, the solid-state polymerization may be performed after the condensation polymerization reaction step, and may be performed at a temperature of 190°C to 230°C, under vacuum conditions of 0.2 torr to 2.0 torr, or under a nitrogen atmosphere.

[0178]

[0179] Method for producing a recycled polyester resin composition

[0180] A method for producing a recycled polyester resin composition according to another embodiment of the present invention may include a step of mixing a recycled polyester resin comprising repeating units derived from a glycol component and repeating units derived from recycled dimethyl terephthalate (rDMT); a hindered phenol-based primary antioxidant; and a phosphorus- or sulfur-based secondary antioxidant.

[0181] According to another embodiment, in the mixing step, a wax-based slip agent including at least one selected from the group consisting of fatty acid esters, fatty acid amides, polyethylene waxes, vegetable waxes, and mineral waxes may be additionally added. According to another embodiment, in the mixing step, at least one additive selected from the group consisting of flame retardants, nucleating agents, coupling agents, fillers, plasticizers, impact modifiers, lubricants, antibacterial agents, release agents, inorganic additives, UV stabilizers, antistatic agents, pigments, and dyes may be additionally added.

[0182] The amount of the above mixed components can be appropriately adjusted to match the content in the recycled polyester resin composition exemplified above.

[0183] In addition, the above-mentioned recycled polyester resin composition can be processed into pellet form after mixing. For example, after feeding the recycled polyester resin composition into an extruder, volatile gases can be decompressed and the composition can be manufactured into pellet form using a chip cutter at about 200°C to 300°C.

[0184]

[0185] The above contents are explained in more detail with the following examples. However, the following examples are only intended to illustrate the present invention, and the scope of the examples is not limited to these examples.

[0186]

[0187] Manufacturing of recycled dimethyl terephthalate (rDMT)

[0188] Manufacturing Example 1

[0189] 120 g of waste polyethylene terephthalate (waste PET) and 400 g of methanol were charged into a first high-pressure reactor with a capacity of 1 L, and 120 mg of Zn(OAC)2·2H2O (1,000 ppm based on the total weight of the waste PET) was added as an alcoholysis catalyst.

[0190] Afterwards, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 220°C over 1 hour. While maintaining the temperature of 220°C and the pressure of 58 bar, depolymerization through alcoholysis was performed by stirring for 3 hours. After the alcoholysis was completed, it was cooled to room temperature, and crystallization was performed by low-speed stirring at 10 to 20 rpm for 2 hours, and a slurry-type alcoholysis composition was obtained. At this time, the alcoholysis composition included solid-phase recycled dimethyl terephthalate (rDMT), an excess of unreacted methanol, and an ethylene glycol derivative produced as a side reaction.

[0191] Thereafter, the alcoholysis composition was placed in a centrifuge to perform solid-liquid separation, dried in an oven at 100°C, and washed with methanol. This process was repeated three or more times to obtain rDMT in the form of a wet cake. The washed rDMT in the form of a wet cake was subjected to fractional distillation at a temperature of 205°C under a reduced pressure condition of 100 torr or less, and cooled to room temperature to obtain additionally purified solid rDMT. At this time, the components and contents of ethylene glycol derivatives produced as a side reaction or terephthalic acid and terephthalate derivatives produced in addition to the target DMT were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0192] Afterwards, the above-mentioned solid rDMT was filtered, and the remaining filtrate was poured into a separate flask, and an excess of unreacted methanol and ethylene glycol (EG) produced as a side reaction were recovered using a fractional distillation device.

[0193]

[0194] Manufacturing Example 2

[0195] 1,000 g of waste polyethylene terephthalate (waste PET), 4,000 g of ethylene glycol, and 3.5 g of zinc acetate anhydride were placed in a stainless steel (SUS) reactor, and the internal temperature of the reactor was raised to 196°C to perform primary depolymerization through glycolysis for 4 hours.

[0196] Thereafter, the first depolymerization composition was cooled to 30°C and stirred at 10 to 20 rpm for 2 hours to proceed with crystallization, and as a result, a slurry containing regenerated bis(2-hydroxyethyl) terephthalate (rBHET) and an excess of ethylene glycol (EG) was obtained.

[0197] Thereafter, the slurry was placed in a centrifuge to perform solid-liquid separation, washed twice with distilled water, and the residual solvent was removed using an oven at 80°C to obtain about 1,000 g of solid rBHET. At this time, the components and contents of the terephthalic acid and terephthalate derivatives produced in addition to the ethylene glycol derivatives produced as a side reaction or the desired bis(2-hydroxyethyl) terephthalate (rBHET) were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0198] Afterwards, the above-mentioned solid rBHET was filtered, and the remaining filtrate was poured into a separate flask, and an excess of unreacted ethylene glycol (EG) was recovered using a fractional distillation device.

[0199] Afterwards, 150 g of the solid rBHET and 400 g of methanol were introduced into the first high-pressure reactor with a capacity of 1 L, and 45 mg of Zn(OAC)2·2H2O (300 ppm relative to the total weight of the rBHET) was added as an alcoholysis catalyst.

[0200] Thereafter, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 90°C over 1 hour. The secondary depolymerization through alcoholysis was performed by stirring for 5 hours while maintaining the temperature at 90°C and the pressure at 3 bar. After the alcoholysis was completed, the secondary depolymerization composition was cooled to room temperature and left for 4 hours to obtain a slurry-type secondary depolymerization composition. At this time, the secondary depolymerization composition contained solid-phase regenerated dimethyl terephthalate (rDMT), an excess of unreacted methanol, and an ethylene glycol derivative produced as a side reaction.

[0201] Thereafter, the secondary depolymerization composition was placed in a centrifuge to perform solid-liquid separation, dried in an oven at 100°C, and washed with methanol. This process was repeated three or more times to obtain rDMT in the form of a wet cake. The washed rDMT in the form of a wet cake was subjected to fractional distillation at a temperature of 205°C and a reduced pressure of 100 torr or less, and cooled to room temperature to obtain additionally purified solid rDMT. At this time, the components and contents of ethylene glycol derivatives produced as a side reaction or terephthalic acid and terephthalate derivatives produced other than the target DMT were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0202] Afterwards, the above-mentioned solid rDMT was filtered, and the remaining filtrate was poured into a separate flask, and an excess of unreacted methanol and ethylene glycol (EG) produced as a side reaction were recovered using a fractional distillation device.

[0203]

[0204] Manufacturing Example 3

[0205] 1,000 g of waste polyethylene terephthalate (waste PET), 4,000 g of ethylene glycol, and 3.5 g of zinc acetate anhydride were placed in a stainless steel (SUS) reactor, and the internal temperature of the reactor was raised to 196°C to perform primary depolymerization through glycolysis for 4 hours.

[0206] Thereafter, the first depolymerization composition was cooled to 30°C and stirred at 10 to 20 rpm for 2 hours to proceed with crystallization, and as a result, a slurry containing regenerated bis(2-hydroxyethyl) terephthalate (rBHET) and an excess of ethylene glycol (EG) was obtained.

[0207] Thereafter, the slurry was placed in a centrifuge to perform solid-liquid separation, washed twice with distilled water, and the residual solvent was removed using an oven at 80°C to obtain about 1,000 g of solid rBHET. At this time, the components and contents of the terephthalic acid and terephthalate derivatives produced in addition to the ethylene glycol derivatives produced as a side reaction or the desired bis(2-hydroxyethyl) terephthalate (rBHET) were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0208] Afterwards, the above-mentioned solid rBHET was filtered, and the remaining filtrate was poured into a separate flask, and an excess of unreacted ethylene glycol (EG) was recovered using a fractional distillation device.

[0209] Afterwards, 150 g of the solid rBHET and 400 g of methanol were introduced into the first high-pressure reactor with a capacity of 1 L, and 45 mg of Zn(OAC)2·2H2O (300 ppm relative to the total weight of the waste rBHET) was added as an alcoholysis catalyst.

[0210] Thereafter, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 220°C over 1 hour. The secondary depolymerization through alcoholysis was performed by stirring for 3 hours while maintaining the temperature of 220°C and the pressure of 58 bar. After the alcoholysis was completed, the mixture was cooled to room temperature and left for 3 hours to obtain a slurry-type secondary depolymerization composition. At this time, the secondary depolymerization composition contained solid-phase recycled dimethyl terephthalate (rDMT), an excess of unreacted methanol, and an ethylene glycol derivative produced as a side reaction.

[0211] Thereafter, the secondary depolymerization composition was placed in a centrifuge to perform solid-liquid separation, and dried in a 100°C oven to obtain solid rDMT. At this time, the components and contents of terephthalic acid and terephthalate derivatives produced in addition to the ethylene glycol derivatives produced as side reactions or the desired DMT were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0212] Afterwards, the above-mentioned solid rDMT was filtered, and the remaining filtrate was poured into a separate flask, and an excess of unreacted methanol and ethylene glycol (EG) produced as a side reaction were recovered using a fractional distillation device.

[0213]

[0214] Manufacturing Example 4

[0215] 1,000 g of waste polyethylene terephthalate (waste PET), 4,000 g of ethylene glycol, and 3.5 g of zinc acetate anhydride were placed in a stainless steel (SUS) reactor, and the internal temperature of the reactor was raised to 196°C to perform primary depolymerization through glycolysis for 4 hours.

[0216] Thereafter, the first depolymerization composition was cooled to 30°C and stirred at 10 to 20 rpm for 2 hours to proceed with crystallization, and as a result, a slurry containing regenerated bis(2-hydroxyethyl) terephthalate (rBHET) and an excess of ethylene glycol (EG) was obtained.

[0217] Thereafter, the slurry was placed in a centrifuge to perform solid-liquid separation, washed twice with distilled water, and the residual solvent was removed using an oven at 80°C to obtain about 1,000 g of solid rBHET. At this time, the components and contents of the terephthalic acid and terephthalate derivatives produced in addition to the ethylene glycol derivatives produced as a side reaction or the desired bis(2-hydroxyethyl) terephthalate (rBHET) were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0218] Afterwards, 150 g of the solid rBHET and 400 g of methanol were introduced into the first high-pressure reactor with a capacity of 1 L, and 150 mg of Zn(OAC)2·2H2O (1,000 ppm relative to the total weight of the rBHET) was added as an alcohol decomposition catalyst.

[0219] Thereafter, all the connecting parts of the first high-pressure reactor were fastened and sealed, and the temperature was raised to 220°C over 1 hour. The secondary depolymerization through alcoholysis was performed by stirring for 3 hours while maintaining the temperature of 220°C and the pressure of 58 bar. After the alcoholysis was completed, the mixture was cooled to room temperature and left for 3 hours to obtain a slurry-type secondary depolymerization composition. At this time, the secondary depolymerization composition contained solid-phase recycled dimethyl terephthalate (rDMT), an excess of unreacted methanol, and an ethylene glycol derivative produced as a side reaction.

[0220] Thereafter, for the secondary depolymerization composition, first fractional distillation was performed under the conditions of 60°C and 500 mmHg, second fractional distillation was performed under the conditions of 170°C and 300 mmHg, and third fractional distillation was performed under the conditions of 200°C and 60 mmHg to obtain solid rDMT. At this time, the components and contents of ethylene glycol derivatives produced as side reactions or terephthalic acid and terephthalate derivatives produced other than the target DMT were analyzed using high-performance liquid chromatography (UPLC) (see Table 2 below).

[0221] Afterwards, the above-mentioned solid rDMT was filtered, and the remaining filtrate was poured into a separate flask, and an excess of unreacted methanol and ethylene glycol (EG) produced as a side reaction were recovered using a fractional distillation device.

[0222]

[0223] Experimental Example 1-1: High-Performance Liquid Chromatography (UPLC)

[0224] Using high-performance liquid chromatography (UPLC), the purity of rDMT obtained in Manufacturing Examples 1 to 4 and rBHET obtained in Manufacturing Example 2 was calculated, and the components and contents of ethylene glycol derivatives produced as side reactions or terephthalic acid or terephthalate derivatives produced other than the desired DMT or BHET were analyzed.

[0225] Specifically, 0.01 g of the sample was diluted in 20 mL of a mixture of methanol and 0.3% distilled aqueous phosphoric acid solution according to the mobile phase and flow rate in Table 1 below, and the peak area was measured using high-performance liquid chromatography (Manufacturer: Water, Model: ACQUITY UPLC H-Class Systems), and the fraction (%) with respect to the total peak area was calculated to measure purity, components produced by side reactions, and components produced other than the target DMT and their contents. At this time, commercially available DMT (Manufacturer: SK Chemicals, Model: SKYDMT) was also listed in Table 2 as a control.

[0226]

[0227]

[0228] Experimental Example 1-2: APHA Color Values

[0229] The APHA (American Public Health Association) color value was measured for the rDMT obtained in the above Manufacturing Examples 1 to 4 and the rBHET obtained in the above Manufacturing Example 2 according to ASTM-D1209. Specifically, the rDMT and the rBHET were dissolved in a dimethylformamide solvent at a concentration of 10 wt% according to ASTM-D1209, placed in an analysis container made of quartz and having a light path length of 10 mm, and then the APHA color value was measured using the transmittance mode of a colorimeter (model name: ColorEye7000A).

[0230]

[0231]

[0232] As shown in Table 2 above, the rDMT of Manufacturing Examples 1 and 2 manufactured according to one embodiment of the present invention had a high purity of 95% or more and excellent transparency with an APHA color value of 85 or less. In particular, Manufacturing Examples 1 and 2 had low contents of ethylene glycol and diethylene glycol, so they had excellent purity and crystallinity, and had low contents of terephthalate derivatives such as methyl hydrogen terephthalate (MHT) in addition to the target DMT, so they are suitable for use as raw materials for various polymers.

[0233] In addition, Manufacturing Example 3, which did not perform the washing process using methanol, had a low purity of less than 90%, and Manufacturing Example 4, which performed the conventional fractional distillation process, had an APHA color value of 125, which was very low in transparency, and the purity was also very low at about 68%.

[0234]

[0235] Manufacturing of recycled polyester resin

[0236] Suzy A

[0237] Step (1): Preparation of regenerated bis(4-hydroxybutyl)terephthalate (rBHBT) through transesterification reaction

[0238] A 1 L transesterification reactor, which was connected to a condenser and a column that could be cooled by water, was charged with 3,068 g of 1,4-butanediol (BD) as a glycol component, 4,407 g of rDMT prepared in Preparation Example 1 as an acid component, and 2 g of tetrabutyl titanate (TBT) as a transesterification catalyst. The pressure inside the reactor was adjusted to 0.1 kg / cm2 by flowing nitrogen, and the temperature was increased to 200°C while maintaining this pressure, and the transesterification reaction was performed while maintaining 200°C. At this time, while the transesterification reaction was proceeding, methanol as a by-product was discharged through the column and condenser, and the transesterification reaction was performed until the discharge of methanol stopped, thereby obtaining a transesterification reaction composition including rBHBT and its oligomers. After the transesterification reaction was completed, the nitrogen inside the pressurized reactor was discharged to the outside to lower the pressure of the reactor to normal pressure.

[0239] Step (2): Production of recycled polyester resin through polycondensation reaction

[0240] The transesterification reaction composition obtained in the above step (1) was introduced into a polycondensation reactor. The pressure of the reactor 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 245°C over 1 hour. Thereafter, 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 high in the early stage of the polycondensation reaction, and as the polycondensation reaction progressed, the stirring speed was appropriately adjusted when the by-product glycol component escaped from the reactor, the stirring force weakened due to the increase in the viscosity of the mixture in the reactor, or the temperature of the mixture rose above the set temperature. The polycondensation reaction was conducted until the intrinsic viscosity (IV) of the mixture (melt) in the reactor became 1.14 dl / g. When the intrinsic viscosity of the mixture within the reactor reached a desired level, the mixture was discharged outside the reactor to form strands, which were then solidified with a cooling liquid and granulated to an average weight of about 12 mg to 14 mg, thereby obtaining 5,000 g of recycled polyester (rPBT) resin.

[0241]

[0242] Suzy B

[0243] Except that in the above step (1), rDMT manufactured in Manufacturing Example 2 was used instead of rDMT manufactured in Manufacturing Example 1, an ester exchange reaction was carried out in the same manner as in Example 1, and in the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 0.98 dl / g, thereby obtaining 5,000 g of a recycled polyester (rPBT) resin.

[0244]

[0245] Suzy C

[0246] In the above step (2), condensation polymerization was performed in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 0.72 dl / g, thereby obtaining 5,000 g of recycled polyester (rPBT) resin.

[0247]

[0248] Suzy D

[0249] Except that commercially available DMT (manufacturer: SK Chemicals, model name: SKYDMT) was used instead of the rDMT manufactured in Manufacturing Example 1 in the above step (1), the ester exchange reaction was carried out in the same manner as in Example 1, and in the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 1.11 dl / g, thereby obtaining 5,000 g of general polyester (PBT) resin.

[0250]

[0251] Suzy E

[0252] Except that in the above step (1), rDMT manufactured in Manufacturing Example 3 was used instead of rDMT manufactured in Manufacturing Example 1, an ester exchange reaction was carried out in the same manner as in Example 1, and in the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 1.1 dl / g, thereby obtaining 5,000 g of a recycled polyester (rPBT) resin.

[0253]

[0254] Suzy F

[0255] Except that in the above step (1), rDMT manufactured in Manufacturing Example 4 was used instead of rDMT manufactured in Manufacturing Example 1, an ester exchange reaction was carried out in the same manner as in Example 1, and in the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 0.9 dl / g, thereby obtaining 5,000 g of a recycled polyester (rPBT) resin.

[0256]

[0257] Suzy G

[0258] An ester exchange reaction was carried out in the same manner as in Example 1 except that 2,836 g of 1,4-butanediol (BD) was used as a glycol component in the above step (1), and 2,852 g of rDMT manufactured in Preparation Example 4 and 1,600 g of rBHET manufactured in Preparation Example 2 were used as acid components, and in the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 0.83 dl / g, thereby obtaining 5,000 g of a recycled polyester (rPBT) resin.

[0259]

[0260] Suzy H

[0261] An ester exchange reaction was carried out in the same manner as in Example 1, except that 1,783 g of 1,4-butanediol (BD) was used as a glycol component in the above step (1), and 6,287 g of rBHET prepared in Preparation Example 2 was used as an acid component. In the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 0.81 dl / g, thereby obtaining 5,000 g of a recycled polyester (rPBT) resin.

[0262]

[0263] Suzy I

[0264] An ester exchange reaction was carried out in the same manner as in Example 1 except that 1,286 g of 1,4-butanediol (BD) was used as a glycol component in the above step (1) and 7,257 g of rBHET prepared in Preparation Example 2 was used as an acid component. In the above step (2), polycondensation was carried out in the same manner as in Example 1 until the intrinsic viscosity (IV) in the reactor became 0.78 dl / g, thereby obtaining 5,000 g of a recycled polyester (rPBT) resin.

[0265]

[0266] Experimental Example 2-1: WAXD (Wide Angle X-Ray Diffraction) Analysis

[0267] For the above resins A to I, WAXD plate photographs were taken using a SmartLab type X-ray diffractometer from Rigaku. At this time, the shooting conditions were set as follows.

[0268] - X-ray generator: 3kW (Cu target)

[0269] - Theta-Theta goniometer with horizontal sample mounting

[0270] - Detector: D / teX Ultra250

[0271] - Application Software: PDXL

[0272] - ICDD Database PDF-2

[0273] When analyzing WAXD, correction data that corrected polarization factor, absorption factor, and air scattering were used for the measured data. From the WAXD pattern derived from X-ray diffraction (XRD) analysis, deconvolution was performed by single line fitting using the Fundamental parameter (FP) approach of the fitting program (Bruker TOPAS), and the crystallized region peak and the amorphous region peak at 2θ values ​​of 0° to 50° were separated, and the area and area ratio of each peak were calculated (see Figs. 2 to 6). The crystallized area value (%) was calculated for the area of ​​each peak according to the following Equation 1.

[0274] [Formula 1]

[0275]

[0276] Figure 1 shows the X-ray diffraction (XRD) analysis of resins A, D, E, H, and I. As shown in Figure 1, the recycled polyester resin A exhibited strong diffraction peaks due to crystals at angles (2θ, Braggs angles) of 9, 15.9, 17.2, 20.6, 23.4, and 25.1. These correspond to diffraction planes (001), (011), (010), (110), (100), and (111), which correspond to the α crystal form of PBT. However, the recycled polyester resins manufactured in Comparative Examples 2, 5, and 6 had low crystallinity because the positions of the peak angles corresponding to each diffraction plane shifted or the areas of the peaks decreased.

[0277]

[0278] Experimental Example 2-2: color-b and color-L

[0279] For the above resins A to I, the color-b value and color-L value, which are color characteristics, were measured using a colorimeter.

[0280] Specifically, the recycled polyester resin was manufactured into a specimen with a width of 30 mm, a length of 30 mm, and a thickness of 6 mm using a hot press, and transmission data was obtained with Illuminant D65 at an observer angle of 2°, and this was processed using a color analysis device within the Grams / 32 software to measure the color-b value and color-L value of Hunter Lab.

[0281]

[0282] Experimental Example 2-3: Intrinsic Viscosity

[0283] The above resins A to I were dissolved in orthochlorophenol (OCP) at 150°C at a concentration of 0.12%, and then the intrinsic viscosity was measured using a Ubbelrod viscometer in a constant temperature bath at 35°C. Specifically, the temperature of the viscosity tube was maintained at 35°C, and the time taken for the solvent to pass through a specific internal section of the viscosity tube (efflux time) and the time taken for the solution to pass through were measured to obtain the specific viscosity, which was then used to calculate the intrinsic viscosity.

[0284]

[0285] Experimental Example 2-4: Tm and △Hm

[0286] For the above resins A to I, the melting point (Tm) and melting enthalpy (△Hm) were calculated using differential scanning calorimetry (DSC, TA Instruments).

[0287] Specifically, the above-mentioned recycled polyester resin was dried under reduced pressure at 50°C for 15 hours, melted at 260°C, rapidly cooled to 30°C, and measured by scanning at a heating rate of 10°C / min using a differential scanning calorimeter. At this time, the melting enthalpy can be measured by using the 1st scan or the 2nd scan using the differential scanning calorimeter, and in this experimental example, it was measured by using the 2nd scan.

[0288] In the heat flow curve obtained by scanning, the first endothermic temperature is the glass transition temperature (Tg), the exothermic temperature measured after the glass transition temperature (Tg) is the crystallization temperature (Tc), and the endothermic temperature measured after the crystallization temperature (Tc) is the melting point (Tm). In addition, the integral at the melting point (Tm) was calculated as the melting enthalpy (△Hm).

[0289]

[0290] Experimental Example 2-5: Heat Deflection Temperature (HDT) (1)

[0291] For the above resins A to I, specimens were prepared according to ASTM D648, and the heat distortion temperature was measured at a low load of 0.48 MPa using a 6M-2 model testing machine from Toyoseiki.

[0292]

[0293] Experimental Example 2-6: 1 H-NMR

[0294] The above resins A to I were each dissolved in CDCl3 solvent at a concentration of 3 mg / mL and then analyzed using a nuclear magnetic resonance device (JEOL, 600 MHz FT-NMR) at 25°C. 1 H-NMR spectrum was obtained. 1 The total content (mol%) of ethylene glycol residues and diethylene glycol residues was calculated based on the total mole number of residues derived from all glycols (EG, DEG, TEG, BD, etc.) by analyzing the H-NMR spectrum.

[0295]

[0296]

[0297]

[0298] As shown in Table 3 above, the recycled polyester resins of resins A to C were manufactured using rDMT having excellent purity, crystallinity, and color characteristics, and thus, they had excellent crystallinity as well as characteristics such as color, melting point (Tm), melting enthalpy, and heat distortion temperature, such as color-b and color-L.

[0299] More specifically, the recycled polyester resins of Resins A to C had excellent crystallinity, with a difference in the crystallized area value according to Formula 1 of 5.8 or more, compared to Resin D, which uses commercially available dimethyl terephthalate rather than recycled dimethyl terephthalate, while satisfying a crystallized area value according to Formula 1 of 20% or more. In addition, the recycled polyester resins of Resins A to C had excellent purity and crystallinity, since the total content of ethylene glycol residues and diethylene glycol residues was 5 mol% or less based on the total molar number of all glycols and derivatives thereof.

[0300] In addition, the recycled polyester resins G using rDMT having a purity of less than 90% as an acid component alone or using such rDMT together with rBHET, and H to I using rBHET alone, had crystallized area values ​​of 20% or less according to Equation 1, which were lower in crystallinity than the resin D using commercially available dimethyl terephthalate rather than recycled dimethyl terephthalate. In addition, the recycled polyester resins G to I also had lower color characteristics such as color-b and color-L, and characteristics such as melting point (Tm), melting enthalpy, and heat distortion temperature.

[0301]

[0302] Manufacturing of recycled polyester resin pellets

[0303] Examples 1 to 5 and Comparative Examples 1 to 8

[0304] The components described in Table 4 below were uniformly mixed as described in Tables 5 and 6 below to prepare a resin composition. The resin composition was automatically metered and fed into the hopper of a twin-screw extruder (40 mm Extruder, L / D: 40), volatile gases were removed under reduced pressure, and pellets were prepared using a chip cutter at about 250°C. At this time, information on the components used in the examples and comparative examples is shown in Table 4 below, and the values ​​described in Tables 5 and 6 below represent parts by weight.

[0305]

[0306]

[0307]

[0308]

[0309] Experimental Example 3-1: Heat Deflection Temperature (HDT) (2)

[0310] For the recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7, specimens were prepared according to ASTM D648, and the specimens were aged and crystallized in a hot air oven at 110°C for 12 hours. Then, the heat distortion temperature was measured at a low load of 0.45 MPa using a 6M-2 model tester from Toyoseiki.

[0311]

[0312] Experimental Example 3-2: Melt Flow Index (MI)

[0313] For the recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7, the melt flow index (MI) was measured under the conditions of 250°C and 2.16 kg according to ASTM D1238.

[0314]

[0315] Experimental Example 3-3: Tensile strength

[0316] For the recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7, the tensile strength (MPa) was measured according to ASTM D638.

[0317]

[0318] Experimental Example 3-4: TVOC (Total Volatile Organic Content) Evaluation

[0319] For the recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7, the total volatile components were quantified as follows according to the Head Space - Gas Chromatography / Mass Spectrometry (HS-GC / MS) analysis method.

[0320] 1) Sample preparation

[0321] After placing approximately 0.1 g of sample in an HS vial (20 mL), seal it with a clamp and measure.

[0322] 2) HS (Head space) device conditions

[0323] ① Model: Triplus 500 (Thermo)

[0324] ② Incubation temperature: 130 ℃

[0325] ③ Incubation time: 300 min

[0326] ④ Loop temperature: 200 ℃

[0327] ⑤ Loop volume: 1 mL

[0328] ⑥ Injection time: 0.5 min

[0329] ⑦ Injection mode: standard

[0330] 3) GC / MS instrument conditions

[0331] ① Model: Thermo 13010 / ISQ7000

[0332] ② Column: DB-5MS (60 m × 0.32 mm × 1.0 μm)

[0333] ③ Oven temp.: 40 ℃ (5 min) - 10 ℃ / min - 300 (5 min)

[0334] ④ Injection temperature: 200 ℃

[0335] ⑤ Split ratio: 1:30

[0336] ⑥ Flow rate: 1.5 mL / min (constant flow)

[0337] ⑦ Ionsource & Transfer line Temperature: 250, 250 ℃

[0338] ⑧ Mass range: 29-300

[0339]

[0340] Experimental Example 3-5: Fogging Test

[0341] For the recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7, fogging evaluation was performed according to the DIN 75201-A test method.

[0342] Specifically, 15 g of the above pellets were placed in a glass petri dish (thickness: 2 mm) with a diameter of 100 mm and a height of 20 mm, covered with a glass petri dish (thickness: 2 mm) with a diameter of 120 mm and a height of 20 mm, and heated on a hot plate at 130°C for 5 hours. Then, the haze values ​​of the glass petri dish used as the cover before and after heating were measured to calculate the haze change (|haze value before heating - haze value after heating|) due to the volatile gas deposited on the glass plate, and fogging evaluation was performed based on this. At this time, the haze (%) was measured using NDH5000 of Nippon Denshoku, and the haze change value was calculated according to the following Equation 2.

[0343] [Formula 2]

[0344] Haze change value = |H1 - H2|

[0345] In equation 2,

[0346] H1 is the unit-less haze value measured before fogging evaluation under the conditions of 130℃ and 5 hours.

[0347] H2 is the unit-excluding haze value due to gas generated during fogging evaluation under conditions of 130℃ and 5 hours.

[0348]

[0349] Experimental Example 3-6: Evaluation of oxidative induction time (OIT)

[0350] For the recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7, the time at which an oxidation exothermic reaction occurs was measured to evaluate the oxidation induction time.

[0351] Specifically, the pellets were dried under reduced pressure at 50°C for 15 hours, and heated from 30°C to 240°C at 10°C / min using a differential scanning calorimeter (DSC, TA Instruments) in a nitrogen atmosphere. Thereafter, the conditions were switched from nitrogen to air at a conversion rate of 20 ml / min, and 240°C was maintained for 60 minutes, and the time for the oxidation exothermic reaction to occur was measured.

[0352]

[0353] Experimental Example 3-7: Injection Flow Mark

[0354] The recycled polyester resin pellets manufactured in Examples 1 to 6 and Comparative Examples 1 to 7 were each injected into a flat plate measuring 120 mm × 120 mm × 2T to manufacture a molded product. The exterior surface of the manufactured molded product was observed with the naked eye, and whether or not a striped flow mark was observed was evaluated as ○ or ×.

[0355]

[0356]

[0357]

[0358]

[0359] As shown in Tables 7 and 8, the recycled polyester resin pellets of Examples 1 to 6 all satisfied the desired numerical ranges in terms of melt flow index (mi), tensile strength, and heat distortion temperature, and also exhibited excellent characteristics in the TVOC evaluation, fogging evaluation, oxidation induction time evaluation, and injection flow mark evaluation. In particular, the recycled polyester resin pellets of Examples 1 to 6 exhibited characteristics equivalent to or better than those of Comparative Example 1, which was manufactured using Resin D, which uses commercially available dimethyl terephthalate rather than recycled dimethyl terephthalate.

Claims

A recycled polyester resin comprising repeating units derived from a glycol component and repeating units derived from recycled dimethyl terephthalate (rDMT); Hindered phenolic primary antioxidant; and Contains a secondary antioxidant of phosphorus or sulfur, The above recycled polyester resin is, A recycled polyester resin composition having a crystallized area value of 20% or more, calculated according to the following Equation 1, for crystallized and non-crystallized regions obtained by separating crystal diffraction peaks appearing at 2θ values ​​of 0° to 50° during X-ray diffraction (XRD) analysis using an individual peak fitting method: [Formula 1] 　 In the first paragraph, Based on 100 parts by weight of the above recycled polyester resin, A recycled polyester resin composition comprising 0.001 to 0.3 parts by weight of the primary antioxidant and 0.001 to 0.2 parts by weight of the secondary antioxidant. 　 In the first paragraph, A recycled polyester resin composition further comprising a wax-based slip agent comprising at least one selected from the group consisting of fatty acid esters, fatty acid amides, polyethylene waxes, vegetable waxes, and mineral waxes. 　 In the third paragraph, A recycled polyester resin composition, wherein the content of the wax-based slip agent is 0.001 to 0.2 parts by weight based on 100 parts by weight of the recycled polyester resin. 　 In the first paragraph, The above-mentioned recycled polyester resin composition further comprises at least one additive selected from the group consisting of flame retardants, nucleating agents, coupling agents, fillers, plasticizers, impact modifiers, lubricants, antibacterial agents, release agents, inorganic additives, ultraviolet stabilizers, antistatic agents, pigments, and dyes. 　 In the first paragraph, The above-mentioned recycled polyester resin composition, The melt flow index (MI) measured under the conditions of 250℃ and 2.16 kg according to ASTM D1238 is 60 g / 10 min or more, Tensile strength according to ASTM D638 is 45 MPa or more, A recycled polyester resin composition having a heat deflection temperature (HDT) of 175°C or higher, measured at a low load of 0.45 MPa according to ASTM D648. 　 In the first paragraph, The above-mentioned recycled polyester resin composition is a recycled polyester resin composition having a TVOC peak area of ​​80 area / g or less as measured by a gas chromatography / mass spectrometry (GC / MS) analysis method. 　 In the first paragraph, The above-mentioned recycled polyester resin composition is a recycled polyester resin composition having a haze change value of 5 or less according to the following formula 2: [Formula 2] Haze change value = |H1 - H2| In equation 2, H1 is the haze value measured before performing fogging evaluation under the conditions of 130℃ and 5 hours according to the DIN 75201-A test method for pellets manufactured using a recycled polyester resin composition, excluding the unit. H2 is the unit-excluding haze value due to gas generated during fogging evaluation at 130°C for 5 hours according to DIN 75201-A test method for pellets manufactured using a recycled polyester resin composition. 　 In the first paragraph, A recycled polyester resin composition, wherein the pellets manufactured using the above recycled polyester resin composition are dried under reduced pressure at 50°C for 15 hours, heated from 30°C to 240°C at 10°C / min using a differential scanning calorimeter (DSC, TA Instruments) in a nitrogen atmosphere, and then the conditions are changed from nitrogen to air at a conversion rate of 20 ml / min, and the oxidation exotherm time measured while maintaining 240°C for 60 minutes is 10 minutes or more. 　 In the first paragraph, The above-mentioned recycled polyester resin is a recycled polyester resin composition in which the difference in crystallized area value according to the following formula 3 is negative: [Formula 3] Difference in crystallized area values ​​= Ca1- Ca2 In the above equation 3, Ca1 is a value excluding the unit from the crystallized area value calculated according to the above formula 1 for a polyester resin containing repeating units derived from dimethyl terephthalate, Ca2 is the unit-less value of the crystallized area calculated according to Equation 1 for a recycled polyester resin containing repeating units derived from recycled dimethyl terephthalate (rDMT). 　 In paragraph 10, A recycled polyester resin composition, wherein the difference in the crystallized area value according to the above formula 3 is -0.5 or less. 　 In the first paragraph, The above-mentioned recycled polyester resin is a recycled polyester resin composition in which the total content (mol%) of ethylene glycol residues and diethylene glycol residues is 5 mol% or less based on the total mole number of the glycol component. 　 In the first paragraph, The above recycled dimethyl terephthalate is, The purity is over 90%, A recycled polyester resin composition having an APHA color value of 120 or less. 　 In the first paragraph, The above-mentioned recycled dimethyl terephthalate is a recycled polyester resin composition manufactured by depolymerizing waste polyester. 　 In the first paragraph, The above-mentioned recycled dimethyl terephthalate is a recycled polyester resin composition manufactured by secondary depolymerization of recycled bis(2-hydroxyethyl) terephthalate (rBHET) manufactured by primary depolymerization of waste polyester. 　 In the first paragraph, The above-mentioned recycled polyester resin composition has a melting point of 210°C or higher and a melting enthalpy (△Hm) of 38 J / g or higher as measured in a second scan using a differential scanning calorimeter. 　 In the first paragraph, The above recycled polyester resin is, The intrinsic viscosity at 35℃ is 0.5 dL / g to 1.5 dL / g, color-b is less than or equal to 12, A recycled polyester resin composition having a color-L of 70 or more. 　 In the first paragraph, A recycled polyester resin composition having a melting point of 210°C or higher and a melting enthalpy (△Hm) of 38 J / g or higher as measured in a second scan using a differential scanning calorimeter. 　 In the first paragraph, The above-mentioned recycled polyester resin is a recycled polyester resin composition having a heat deflection temperature (HDT) of 90°C or higher measured at a low load of 0.48 MPa according to ASTM D648. 　 A molded article manufactured from the recycled polyester resin composition of claim 1. 　 In paragraph 20, The above molded product is a molded product for a vehicle headlamp.

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